JPWO2019013169A1 - Polyimide film, laminate, display surface material, touch panel member, liquid crystal display device, and organic electroluminescence display device - Google Patents

Abstract

In the temperature-loss tangent (tan δ) curve obtained by the dynamic viscoelasticity measurement, the maximum value of tan δ in the temperature range from the temperature on the high temperature side minimum value of the first peak having the maximum maximum value to 500 ° C. or less is 0.18. It is above, and the total light transmittance measured based on JISK7361-1 is 85% or more, The polyimide film.

Description

  The embodiment of the present disclosure relates to a polyimide film, a laminate, a surface material for a display, a touch panel member, a liquid crystal display device, and an organic electroluminescence display device.

  Although the thin plate glass has excellent hardness and heat resistance, it has a drawback that it is difficult to bend, it is easily broken when dropped, it has a problem in workability, and it is heavier than plastic products. Therefore, in recent years, resin products such as resin base materials and resin films are being replaced with glass products from the viewpoints of workability and weight reduction, and research has been conducted on resin products as glass substitute products.

  For example, with the rapid progress of displays such as liquid crystal and organic EL, and electronics such as touch panels, there has been a demand for thinner and lighter devices, and more flexible devices. Conventionally, various electronic elements such as thin transistors and transparent electrodes are formed on thin plate glass in these devices. By replacing the thin plate glass with a resin film, the impact resistance of the panel itself is enhanced. Flexible, thin and lightweight.

The polyimide resin is a highly heat-resistant resin obtained by subjecting a polyamic acid obtained by a condensation reaction of a tetracarboxylic acid anhydride and a diamine compound to a dehydration ring-closing reaction. However, since polyimide resins generally show yellow or brown coloring, it has been difficult to use them in fields requiring transparency such as display applications and optical applications. Therefore, application of polyimide having improved transparency to a display member has been studied.
For example, in Patent Document 1, 1,2,4,5-cyclohexanetetracarboxylic acid and 1,2,4,5-cyclohexanetetracarboxylic acid diimide are used as polyimide resins having high heat resistance, high transparency and low water absorption. At least one acyl-containing compound selected from the group consisting of anhydrides and their reactive derivatives, and at least one compound selected from compounds having at least one phenylene group and isopropylidene group represented by a specific formula A polyimide resin obtained by reacting an imino-forming compound has been invented, and it is described that it is suitable as a substrate material for flat panel displays, mobile phone devices and the like.

  Further, in Patent Document 2, a unit structure derived from an aromatic dianhydride and an aromatic diamine is contained, and a tear strength improving additive or a functional group selected from the group consisting of a hexafluoro group, a sulfone group and an oxy group is added. A transparent polyimide film is further described which further includes a unit structure derived from the monomer having the same.

  Further, in Patent Document 3, as a polyimide film having excellent transparency and heat resistance, a curve of tan δ, which is a value obtained by dividing loss elastic modulus by storage elastic modulus, has a peak apex within a range of 280 to 380 ° C. And a polyimide film having an average transmittance of 85% or more at 400 to 740 nm measured by a UV spectrophotometer with a film thickness of 50 to 100 μm as a reference. Patent Document 3 describes that transparency can be improved in the case of a polyimide film showing a second apex in a temperature section before a temperature section showing the highest peak of a tan δ curve.

JP, 2006-199945, A Special table 2014-501301 gazette Special table 2012-503701 gazette

In addition to the above-mentioned transparency and durability, a resin film that replaces glass is required to have a small optical strain.
However, the present inventors have found that a conventional resin film using transparent polyimide has a problem that optical distortion is large, and in particular, a phase difference in a film thickness direction is large.

The present disclosure has been made in view of the above problems, and a main object of the present disclosure is to provide a resin film having good transparency and durability and having reduced optical distortion.
Further, the present disclosure, a laminate having the resin film, and a display surface material that is the resin film or the laminate, and a touch panel member including the resin film or the laminate, a liquid crystal display device, and an organic material. It is an object to provide an electroluminescence display device.

In an embodiment of the present disclosure, in a temperature-loss tangent (tan δ) curve obtained by dynamic viscoelasticity measurement, in a temperature range of a temperature of a high temperature side minimum value of a first peak having a maximum maximum value or more and 500 ° C. or less. the maximum value of tan δ is 0.18 or more,
Provided is a polyimide film having a total light transmittance of 85% or more measured according to JIS K7361-1.

One embodiment of the present disclosure provides the polyimide film, wherein the maximum value of tan δ is 0.18 or more in a temperature range of 300 ° C. or higher and 450 ° C. or lower, which is equal to or higher than a temperature of a high temperature side minimum value of the first peak. provide.
One embodiment of the present disclosure provides the polyimide film, wherein the maximum value of tan δ is 0.18 or more in a temperature range of 350 ° C. or higher and 450 ° C. or lower, which is equal to or higher than the temperature on the high temperature side minimum value of the first peak. provide.

  One embodiment of the present disclosure is an alkylene that includes an aromatic ring, and in which (i) a fluorine atom, (ii) an aliphatic ring, and (iii) aromatic rings are substituted with a sulfonyl group or fluorine. There is provided the above polyimide film, which contains a polyimide containing at least one selected from the group consisting of groups linked by groups.

（一般式（１）において、Ｒ^１は芳香族環又は脂肪族環を有するテトラカルボン酸残基である４価の基を表し、Ｒ^２はジアミン残基である２価の基を表し、芳香族環又は脂肪族環を有するジアミン残基を含む。ｎは繰り返し単位数を表す。）One embodiment of the present disclosure provides the polyimide film, which contains a polyimide having a structure represented by the following general formula (1).

(In the general formula (1), R ¹ represents a tetravalent group that is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ² represents a divalent group that is a diamine residue, and A diamine residue having a group ring or an aliphatic ring is contained, and n represents the number of repeating units.)

One embodiment of the present disclosure is a polyimide having a structure represented by the general formula (1), wherein R ² in the general formula (1) is a diamine residue having no silicon atom and a main chain. It represents a divalent group that is at least one selected from diamine residues having one or two silicon atoms, and 2.5 mol% or more and 50 mol% or less of the total amount of R ² has a silicon atom in the main chain. One or two diamine residues, 50 mol% or more and 97.5 mol% or less is a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring, wherein the polyimide film provide.

One embodiment of the present disclosure is a polyimide having a structure represented by the general formula (1), wherein R ¹ in the general formula (1) is a cyclohexanetetracarboxylic dianhydride residue, cyclopentanetetracarboxylic acid. Acid dianhydride residue, dicyclohexane-3,4,3 ', 4'-tetracarboxylic acid dianhydride residue, cyclobutanetetracarboxylic acid dianhydride residue, pyromellitic acid dianhydride residue, 3, 3 ', 4,4'-biphenyltetracarboxylic dianhydride residue, 2,2', 3,3'-biphenyltetracarboxylic dianhydride residue, 4,4 '-(hexafluoroisopropylidene) diphthalate Acid anhydride residue, 3,4 '-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene) diphthalic anhydride residue, 4,4'-oxydiphthalic acid Anhydride residues, and at least one tetravalent group selected from the group consisting of 3,4'-oxydiphthalic anhydride residue, providing the polyimide film.

（一般式（２）において、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子、アルキル基、またはパーフルオロアルキル基を表す。）One embodiment of the present disclosure is a polyimide having a structure represented by the general formula (1), wherein a diamine residue having the aromatic ring or the aliphatic ring in R ² in the general formula (1) is , Trans-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4′-diaminodiphenylsulfone residue, 3,4′-diaminodiphenylsulfone residue, 2,2-bis (4 -Aminophenyl) propane residue, 3,3'-bis (trifluoromethyl) -4,4 '-[(1,1,1,3,3,3-hexafluoropropane-2,2-diyl) bis (4,1-Phenyleneoxy)] dianiline residue, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, 2, -Bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, and a group consisting of a divalent group represented by the following general formula (2). The above-mentioned polyimide film, which is at least one divalent group selected from the above, is provided.

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.)

  One embodiment of the present disclosure provides a laminate having a polyimide film of the one embodiment of the present disclosure and a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound. ..

  One embodiment of the present disclosure provides a surface material for a display, which is the polyimide film of the one embodiment of the present disclosure or the laminate of the one embodiment of the present disclosure.

Further, one embodiment of the present disclosure is a polyimide film of the one embodiment of the present disclosure or a laminate of the one embodiment of the present disclosure,
Arranged on one surface side of the polyimide film or the laminate, a transparent electrode composed of a plurality of conductive portions,
A touch panel member having a plurality of lead-out lines electrically connected to at least one side of an end of the conductive portion.

Further, one embodiment of the present disclosure is a polyimide film of the one embodiment of the present disclosure or a laminate of the one embodiment of the present disclosure,
A liquid crystal display device, comprising: a liquid crystal display unit having a liquid crystal layer between opposed substrates, which is disposed on one surface side of the polyimide film or the laminate.

Further, one embodiment of the present disclosure is a polyimide film of the one embodiment of the present disclosure or a laminate of the one embodiment of the present disclosure,
Provided is an organic electroluminescence display device, comprising: an organic electroluminescence display unit having an organic electroluminescence layer between opposing substrates, which is disposed on one surface side of the polyimide film or the laminate.

According to the present disclosure, it is possible to provide a resin film having good transparency and durability and having reduced optical distortion.
Further, according to the present disclosure, a laminate having the resin film, and a display surface material that is the resin film or the laminate, and a touch panel member including the resin film or the laminate, a liquid crystal display device, And an organic electroluminescence display device can be provided.

It is a figure showing an example of a tandelta curve, a storage elastic modulus curve, and a loss elastic modulus curve of a polyimide film of this indication. It is a schematic plan view of one surface of an example of a touch panel member of this indication. FIG. 3 is a schematic plan view of the other surface of the touch panel member shown in FIG. 2. FIG. 4 is a cross-sectional view taken along the line A-A ′ of the touch panel member shown in FIGS. 2 and 3. It is a schematic plan view which shows an example of the electroconductive member provided with the laminated body of this indication. It is a schematic plan view which shows another example of the electroconductive member provided with the laminated body of this indication. It is a schematic sectional drawing which shows another example of the touch panel member of this indication. FIG. 3 is a schematic cross-sectional view showing an example of a liquid crystal display device of the present disclosure. FIG. 8 is a schematic cross-sectional view showing another example of the liquid crystal display device of the present disclosure. It is a schematic sectional drawing which shows an example of the organic electroluminescent display apparatus of this indication. It is a schematic sectional drawing which shows another example of the organic electroluminescent display apparatus of this indication. 3 is a diagram showing a tan δ curve, a storage elastic modulus curve, and a loss elastic modulus curve of the polyimide film of Example 1. FIG. 5 is a diagram showing a tan δ curve, a storage elastic modulus curve, and a loss elastic modulus curve of the polyimide film of Example 2. FIG. 5 is a diagram showing a tan δ curve, a storage elastic modulus curve, and a loss elastic modulus curve of the polyimide film of Example 3. FIG. 5 is a diagram showing a tan δ curve, a storage elastic modulus curve, and a loss elastic modulus curve of the polyimide film of Example 4. FIG. 5 is a diagram showing a tan δ curve, a storage elastic modulus curve, and a loss elastic modulus curve of the polyimide film of Example 5. FIG. 5 is a diagram showing a tan δ curve, a storage elastic modulus curve, and a loss elastic modulus curve of the polyimide film of Comparative Example 1. FIG. 5 is a diagram showing a tan δ curve, a storage elastic modulus curve, and a loss elastic modulus curve of the polyimide film of Comparative Example 2. FIG.

I. Polyimide film The polyimide film of one embodiment of this indication WHEREIN: In the temperature-loss tangent (tan (delta)) curve obtained by dynamic viscoelasticity measurement, the maximum value is the temperature of the minimum value of the 1st peak on the high temperature side 500 degreeC or more. The maximum value of tan δ in the temperature range below is 0.18 or more,
The total light transmittance measured according to JIS K7361-1 is 85% or more.

  According to the present disclosure, in the temperature-loss tangent (tan δ) curve obtained by dynamic viscoelasticity measurement, tan δ in a temperature range of the first peak having the maximum maximum value on the high temperature side minimum value to 500 ° C. or less. The maximum value is 0.18 or more, and the total light transmittance measured according to JIS K7361-1 is 85% or more, so that the polyimide film has good transparency and durability, It is possible to provide a resin film with reduced mechanical distortion.

Among the resin films, the present inventors have focused their attention on a polyimide film that is known to have excellent durability due to its chemical structure. In the process of the examination, it was found that the polyimide film has a problem that optical distortion is large, and particularly, a retardation in the film thickness direction is large.
The phase difference is caused by the anisotropy of the refractive index. In the case of a polymer, anisotropy of refractive index generally occurs when polymer chains do not randomly exist in a solid and are regularly arranged with directionality.
Compared with other resins, polyimide has fewer bendable bonding sites in the chemical structure, and thus tends to have more linear molecular structures in the polymer chain. Such a structure is a factor that can increase the elastic modulus, but since it also becomes a factor that tends to be regularly folded in a state where the linear molecular structure is oriented in the film thickness direction, such a polyimide film It is assumed that the phase difference in the film thickness direction becomes large.
In the temperature-loss tangent (tan δ) curve (hereinafter, may be simply referred to as tan δ curve) obtained by dynamic viscoelasticity measurement of a polyimide film, the present inventors have found that the temperature of the local minimum value on the high temperature side of the first peak. It has been found that when the maximum value of tan δ in the temperature range of 500 ° C. or lower (hereinafter, simply referred to as the first peak high temperature side temperature range) is larger than the predetermined value, the phase difference in the film thickness direction becomes small. . The reason for this is not clear, but it is estimated as follows.
The tan δ is a value obtained by dividing the loss elastic modulus by the storage elastic modulus, and indicates the viscoelastic property of the polymer material. FIG. 1 shows an example of a tan δ curve, a storage elastic modulus curve, and a loss elastic modulus curve of the polyimide film of the present disclosure. In FIG. 1, the temperature of the maximum value of the first peak (1) where the maximum value of the tan δ curve is maximum indicates the glass transition point of the polyimide film. Therefore, in the region above the temperature of the maximum value of the first peak (1), most of the polymer chains are in a state of thermal vibration.
A large value of tan δ in the first peak high temperature region indicates that the viscosity is high, that is, it indicates that the intermolecular interaction of the polymer is small. Here, when linear molecular structures are regularly arranged in the polyimide film, intermolecular interaction becomes relatively large, and the mobility of the polymer chains in the first peak high temperature region is high. It is considered that the value decreases and the value of tan δ decreases.
The small value of tan δ in the temperature range above the glass transition temperature indicates that the polymer chains are in a positional relationship in which the interaction between the molecules strongly acts. Is expected to grow.
On the other hand, in a polyimide film in which polymer chains are said to have a small retardation and are irregularly distributed, the intermolecular force becomes relatively small and the polymer chains in the first peak high temperature side temperature region Is likely to vibrate.
For this reason, in the tan δ curve, a polyimide film having a large maximum value of tan δ in the first peak high temperature side temperature region shows a low phase difference because of a high proportion of polymer chains that are randomly present. Conceivable.
In addition, in Example 4 and Comparative Example 1 which will be described later, even when a polyimide film is manufactured using a polyimide precursor having the same molecular structure, the manufacturing method is different and the state of the polymer chains in the polyimide film is different. In the tan δ curve, it is shown that the maximum value of tan δ in the first peak high temperature side temperature region is greatly different, and the magnitude of the phase difference is greatly different accordingly. This means that the retardation of the polyimide film does not depend only on the composition of the polyimide, and the maximum value of tan δ in the first peak high temperature region is the polymer in the polyimide film related to the retardation. It is believed to indicate that it represents the state of the chain.
The inventors of the present invention have conducted a study based on the above findings, and as a result, a sufficiently reduced retardation can be obtained with a polyimide film having a maximum value of tan δ in the first peak high temperature side temperature region of 0.18 or more. I found out that.

1. Temperature-Loss Tangent (tan δ) Curve The polyimide film of the present disclosure has a temperature-loss tangent (tan δ) curve obtained by dynamic viscoelasticity measurement, which has a maximum maximum value on the high temperature side minimum value of the first peak of 500 or more. The maximum value of tan δ in the temperature range of ℃ or less is 0.18 or more. In the polyimide film of the present disclosure, the maximum value of tan δ may be 0.18 or more in the temperature range of not less than 460 ° C., which is the temperature on the high temperature side minimum value of the first peak having the maximum maximum value in the tan δ curve.
The tan δ curve of the polyimide film of the present disclosure has a first peak having a maximum maximum value. As described above, the temperature at the maximum value of the first peak indicates the glass transition temperature of the polyimide film. In the polyimide film of the present disclosure, the temperature range in which the first peak exists is not particularly limited, but it is preferably 400 ° C. or lower from the viewpoint of transparency. On the other hand, from the viewpoint of heat resistance of the polyimide film, the temperature range in which the first peak exists is preferably 200 ° C or higher, and more preferably 250 ° C or higher.
As shown in FIG. 1, the polyimide film of the present disclosure has a temperature range of the temperature (2t) or more and 500 ° C. or less of the high temperature side minimum value (2) of the first peak (1) having the maximum maximum value in the tan δ curve. The maximum value (3) of tan δ in is ≧ 0.18. As described above, in the polyimide film in which the maximum value of tan δ takes such a large value, it is estimated that the proportion of the bent polymer chains that are irregularly present is increased, and the phase difference is sufficiently reduced. Will be able to obtain. From the viewpoint of obtaining a further reduced phase difference, the maximum value of tan δ is preferably 0.20 or more, and more preferably 0.21 or more. The upper limit of the maximum value of tan δ is not particularly limited, but is preferably 0.50 or less, more preferably 0.30 or less.
In the maximum value of tan δ in the temperature range of the high temperature side minimum value of the first peak to 500 ° C. or less, the temperature range from the maximum value of the first peak to the high temperature side minimum value, that is, the decrease of the first peak The value of tan δ in the aspect is not included.
The temperature range above the temperature of the minimum value on the high temperature side of the first peak has a relationship with a preferable temperature range in which the first peak exists, that is, from the viewpoint of transparency and heat resistance of the polyimide film, 200 ° C or higher and 450 ° C or lower. Is more preferable, the temperature range of 250 ° C. or higher and 450 ° C. or lower is more preferable, the temperature range of 300 ° C. or higher and 450 ° C. or lower is more preferable, and the temperature range of 350 ° C. or higher and 450 ° C. or lower Is more preferable.
In the tan δ curve, when a peak is confirmed in a temperature range of the high temperature side minimum value of the first peak or more and 500 ° C. or less, the maximum value of the peak may be 0.18 or more. The maximum value of is more preferably 0.20 or more, still more preferably 0.21 or more.
Further, the peak existing in the temperature range of the temperature on the high temperature side minimum value of the first peak to 500 ° C. or less is the second peak having the second largest maximum value in the tan δ curve, which reduces the phase difference. It is preferable from the point of doing.
In addition, in the tan δ curve, the second peak having the first peak having the maximum maximum value and having the second highest maximum value of 0.18 or more in the temperature region higher than the temperature of the maximum value of the first peak. Having a peak is preferable from the viewpoint of reducing the phase difference. Further, in the tan δ curve, a second peak having the second largest maximum value is present in a temperature range of not less than the temperature on the high temperature side minimum value of the first peak having the largest maximum value and not higher than 500 ° C. The maximum value is preferably 0.18 or more, more preferably 0.20 or more, even more preferably 0.21 or more.

The tan δ curve is obtained from tan δ (tan δ = loss elastic modulus (E ″) / storage elastic modulus (E ′)) by dynamic viscoelasticity measurement. The dynamic viscoelasticity measurement is performed by a dynamic viscoelasticity measuring device RSA-G2 (manufactured by TA Instruments) in a measuring chamber of 23 ° C. and 56% RH, and the measuring range is −40 ° C. or more and 500 ° C. or less as a deformation mode. Tension can be selected, and it can be performed under a nitrogen atmosphere at a frequency of 1 Hz, a temperature rising rate of 10 ° C./min, a minimum load of 2 g, Axial force> Dynamic Force 1.5%, and Strain 0.1%. In addition, a test piece having a length of 40 mm and a width of 5 mm is prepared, and the distance between chucks can be set to 20 mm for measurement. When analyzing peaks and inflection points, do not perform visual evaluation, digitize the data, and analyze from the numerical values.
In the present disclosure, the peak of the tan δ curve refers to a peak having an inflection point that is a maximum value and a peak width between the valleys of the peak that is 3 ° C. or more, and is used to measure noise and the like. Small vertical fluctuations of origin are not interpreted as the peaks.
Further, in the first peak high temperature side temperature region, when the test piece of the polyimide film to be measured is melted, the value of tan δ cannot be accurately measured, so that the numerical value has no continuity and the value of tan δ is extremely high. There is. The case where the film melts and the value of tan δ becomes discontinuous can be used as a standard when the size changes by 0.3 or more at a 1 ° C. pitch. However, since such a value cannot be said to be the value of the tan δ curve, it is not interpreted as the maximum value of tan δ in the temperature range of the temperature of the high temperature side minimum value of the first peak and 500 ° C. or less. That is, the value in the region of the temperature of the minimum value on the high temperature side of the first peak and lower than the temperature at which the film melts is interpreted as the maximum value of tan δ.

2. Total Light Transmittance The polyimide film of the present disclosure has a total light transmittance of 85% or more measured according to JIS K7361-1. Since the transmittance is high as described above, the transparency is improved and it can be used as a glass substitute material. The total light transmittance of the polyimide film of the present disclosure measured according to JIS K7361-1 is preferably 88% or more, more preferably 89% or more, and particularly 90% or more. Preferably.
The polyimide film of the present disclosure has a thickness of 5 μm or more and 100 μm or less, and a total light transmittance measured according to JIS K7361-1 is preferably 85% or more, more preferably 88% or more, It is more preferably 89% or more, and particularly preferably 90% or more.
Further, the polyimide film of the present disclosure has a total light transmittance measured in accordance with JIS K7361-1 of preferably 50% or more and more preferably 88% or more at a thickness of 50 μm ± 5 μm. , And more preferably 89% or more, and particularly preferably 90% or more.
The total light transmittance measured according to JIS K7361-1 can be measured by, for example, a haze meter (for example, HM150 manufactured by Murakami Color Research Laboratory). In addition, from the measured value of the total light transmittance of a certain thickness, the converted value of the total light transmittance of a different thickness can be obtained by the Lambert Beer's law, and the converted value can be used.
Specifically, according to Lambert Beer's law, the transmittance T is
Log ₁₀ (1 / T) = kcb
(K = constant specific to substance, c = concentration, b = optical path length).
In the case of the transmittance of the film, c is also a constant assuming that the density is constant even if the film thickness is changed. Therefore, the above formula is used to calculate Log ₁₀ (1 / T) = fb using the constant f.
It can be expressed as (f = kc). Here, if the transmittance at a certain film thickness is known, the unique constant f of each substance can be obtained. Therefore, the transmittance at a desired film thickness can be obtained by substituting a constant p specific to f and a target film thickness into b using the equation T = 1/10 ^{f · b} .

3. Polyimide In the present disclosure, polyimide is obtained by reacting a tetracarboxylic acid component and a diamine component. After obtaining a polyamic acid as a precursor by polymerizing a tetracarboxylic acid component and a diamine component, this precursor is imidized. Therefore, the polyimide used in the present disclosure has a tetracarboxylic acid residue and a diamine residue in the main chain. The tetracarboxylic acid residue means a residue obtained by removing four carboxyl groups from tetracarboxylic acid, and has the same structure as the residue obtained by removing the acid dianhydride structure from tetracarboxylic dianhydride. Further, the diamine residue means a residue obtained by removing two amino groups from diamine.

As long as the viscoelastic properties and transparency specified in the present disclosure can be obtained, the production of the polyimide film is molded in the state of the polyimide precursor and then carried out by a thermal imidization method to obtain polyimide by heat treatment, and It may be carried out by removing the solvent from the solution that has become polyimide (for example, made into polyimide by chemical imidization), or may be carried out by a method in which both thermal imidization and chemical imidization are used in combination. However, among them, the polyimide film of the present disclosure is preferably manufactured by a method of forming a polyimide film by heating (thermal imidization) after film formation using a polyimide precursor solution, from the viewpoint of easily reducing the phase difference.
Generally, the polyimide precursor has a higher skeleton flexibility than the polyimide, and is more likely to exist in an irregular shape in the film. By imidizing a polyimide precursor that exists in such an irregular state in a substantially solid layer, an irregular structure is easily formed even after the polyimide is formed. As a result, it is estimated that the retardation is likely to be lower in the manufacturing method in which the polyimide film is formed by heating after the film formation of the polyimide precursor.
The polyimide obtained by imidizing a polyimide precursor (polyamic acid) in a solution by chemical imidization has a linear molecular structure because the number of bendable movable parts of the molecular structure is reduced during film formation. Cheap. The polyimide in the obtained polyimide film easily regularly folds in a state of being oriented in a direction parallel to the film thickness, so that intermolecular interaction becomes large and phase difference easily becomes large. However, even when a film is formed from a polyimide solution, there are cases where the polyimide has a flexible skeleton or an irregular state can be created by a method of instantaneously removing the solvent.
For these reasons, it is preferable to use thermal imidization in order to set the maximum value of tan δ in the first peak high temperature region to 0.18 or more in the tan δ curve.

In the polyimide used in the present disclosure, as the tetracarboxylic acid component that becomes a tetracarboxylic acid residue, for example, a tetracarboxylic acid component having an aromatic ring is preferable from the viewpoint of improving the surface hardness of the polyimide film.
As the tetracarboxylic acid component having an aromatic ring, A tetracarboxylic dianhydride having an aromatic ring, For example, Pyromellitic dianhydride, Three 3 ', 4, 4'-benzophenone tetracarboxylic dianhydride, Two 2 ', Three 3'-benzophenone tetracarboxylic dianhydride, Three 3 ', 4, 4'-biphenyltetracarboxylic dianhydride, Two 2 ', Three 3'-biphenyltetracarboxylic dianhydride, Two 2-bis (3 4-dicarboxyphenyl) propane dianhydride, Two 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, Screw (3 4-dicarboxyphenyl) ether dianhydride, Screw (3 4-dicarboxyphenyl) sulfone dianhydride, 1, 1-bis (2 3-dicarboxyphenyl) ethane dianhydride, Screw (2, 3-dicarboxyphenyl) methane dianhydride, Screw (3 4-dicarboxyphenyl) methane dianhydride, Two 2-bis (3 4-dicarboxyphenyl) -1, 1, 1, Three Three 3-hexafluoropropane dianhydride, Two 2-bis (2, 3-dicarboxyphenyl) -1, 1, 1, Three Three 3-hexafluoropropane dianhydride, 1, 3-bis [(3 4-dicarboxy) benzoyl] benzene dianhydride, 1, 4-bis [(3 4-dicarboxy) benzoyl] benzene dianhydride, Two 2-bis {4- [4- (1, 2-dicarboxy) phenoxy] phenyl} propane dianhydride, Two 2-bis {4- [3- (1, 2-dicarboxy) phenoxy] phenyl} propane dianhydride, Bis {4- [4- (1, 2-dicarboxy) phenoxy] phenyl} ketone dianhydride, Bis {4- [3- (1, 2-dicarboxy) phenoxy] phenyl} ketone dianhydride, 4, 4'-bis [4- (1, 2-dicarboxy) phenoxy] biphenyl dianhydride, 4, 4'-bis [3- (1, 2-dicarboxy) phenoxy] biphenyl dianhydride, Bis {4- [4- (1, 2-dicarboxy) phenoxy] phenyl} ketone dianhydride, Bis {4- [3- (1, 2-dicarboxy) phenoxy] phenyl} ketone dianhydride, Bis {4- [4- (1, 2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, Bis {4- [3- (1, 2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, Bis {4- [4- (1, 2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, Bis {4- [3- (1, 2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, 4, 4 '-(hexafluoroisopropylidene) diphthalic anhydride, Three 4 '-(hexafluoroisopropylidene) diphthalic anhydride, Three 3 '-(hexafluoroisopropylidene) diphthalic anhydride, 4, 4'-oxydiphthalic anhydride, Three 4'-oxydiphthalic anhydride, Two Three 6, 7-naphthalene tetracarboxylic dianhydride, 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride, 1, Two 5, 6-naphthalene tetracarboxylic dianhydride, 1, Two Three 4-benzenetetracarboxylic dianhydride, Three 4, 9, 10-perylene tetracarboxylic dianhydride, Two Three 6, 7-anthracene tetracarboxylic dianhydride, 1, Two 7, 8-phenanthrenetetracarboxylic dianhydride and the like can be mentioned.

Further, as the tetracarboxylic acid component used in the present disclosure, a tetracarboxylic acid component having an aliphatic ring is also preferable from the viewpoint of the light transmittance of the polyimide film.
Examples of the tetracarboxylic dianhydride having an aliphatic ring include cyclohexanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, dicyclohexane-3,4,3 ′, 4′-tetracarboxylic dianhydride. An anhydride, cyclobutane tetracarboxylic dianhydride, etc. are mentioned.
The above-mentioned tetracarboxylic acid components may be used alone or in combination of two or more.

As the diamine component, for example, a diamine having an aromatic ring is preferable in terms of durability and surface hardness of the polyimide film.
Further, as the diamine component used in the present disclosure, a diamine having an aliphatic ring is also preferable from the viewpoint of the light transmittance of the polyimide film.
Moreover, it is preferable that the polyimide film which concerns on this indication contains the polyimide containing the diamine residue which has a silicon atom in a main chain above all. In the polyimide containing a diamine residue having a silicon atom in the main chain, since the silicon atom portion may have a bent structure, it is easy to obtain a polyimide having a polymer chain containing more bent molecular structures, the polyimide film of the present disclosure It is preferable because it is easy to obtain.

  Examples of the diamine having an aromatic ring include 4,4′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4- Aminophenyl) hexafluoropropane, p-phenylenediamine, o-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide , 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzanilide, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- 3-aminophenyl) -2- (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-di (4-aminophenyl) -1-phenylethane, 1- (3-Aminophenyl) -1- (4-aminophenyl) -1-phenylethane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3 -Bis (4-aminobenzoyl) benzene, 1,4-bis (4-aminobenzoyl) benzene, 1,3-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (4- Amino-α, α-dimethylbenzyl) benzene, 1,3-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (4-amino-α, α-ditrifluoromethylbenzyl) ) Benzene, N, N'-bis (4-aminophenyl) terephthalamide, 9,9-bis (4-aminophenyl) fluorene, 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3 ' -Dimethoxy-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) Phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis [4- (4-a Nophenoxy) benzoyl] benzene, 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1 , 4-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 4,4′-bis [4- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4 -(4-Amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, 4,4′-bis [ 4- (4-aminophenoxy) phenoxy] diphenyl sulfone, 3,3′-diamino-4,4′-diphenoxybenzophenone, 3,3′-diamino- , 4'-dibiphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6,6'-bis (4-aminophenoxy) -3,3,3 3 ′, 3′-tetramethyl-1,1′-spirobiindane, etc., and a part or all of hydrogen atoms on the aromatic ring of the diamine are fluoro group, methyl group, methoxy group, trifluoromethyl group, or tri A diamine substituted with a substituent selected from a fluoromethoxy group can be used.

  Examples of the diamine having an aliphatic ring include trans-cyclohexanediamine, trans-1,4-bismethylenecyclohexanediamine, 2,6-bis (aminomethyl) bicyclo [2,2,1] heptane, 2,5- Examples thereof include bis (aminomethyl) bicyclo [2,2,1] heptane.

  Examples of the diamine having a silicon atom in the main chain include diamines represented by the following general formula (A).

（一般式（Ａ）において、Ｌはそれぞれ独立して、直接結合又は−Ｏ−結合であり、Ｒ^１０はそれぞれ独立して、置換基を有していても良く、酸素原子又は窒素原子を含んでいても良い炭素数１以上２０以下の１価の炭化水素基を表す。Ｒ^１１はそれぞれ独立して、置換基を有していても良く、酸素原子又は窒素原子を含んでいても良い炭素数１以上２０以下の２価の炭化水素基を表す。ｋは０〜２００の数である。複数あるＬ、Ｒ^１０及びＲ^１１は、それぞれ同一であっても異なっていても良い。）

(In the general formula (A), each L independently represents a direct bond or an —O— bond, and each R ¹⁰ independently may have a substituent and contains an oxygen atom or a nitrogen atom. Represents a monovalent hydrocarbon group having 1 or more and 20 or less carbon atoms, each R ¹¹ may independently have a substituent, and may contain an oxygen atom or a nitrogen atom; It represents a divalent hydrocarbon group having a number of 1 or more and 20 or less.k is a number of 0 to 200. Plural L, R ¹⁰ and R ¹¹ may be the same or different.)

Examples of the monovalent hydrocarbon group represented by R ¹⁰ include alkyl groups having 1 to 20 carbon atoms, aryl groups, and combinations thereof. The alkyl group may be linear, branched, or cyclic, or may be linear or a combination of branched and cyclic.
The alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, Examples thereof include t-butyl group, pentyl group and hexyl group. The cyclic alkyl group is preferably a cycloalkyl group having 3 to 10 carbon atoms, and specific examples thereof include a cyclopentyl group and a cyclohexyl group. The aryl group is preferably an aryl group having 6 to 12 carbon atoms, and specific examples thereof include a phenyl group, a tolyl group and a naphthyl group. Further, the monovalent hydrocarbon group represented by R ¹⁰ may be an aralkyl group, and examples thereof include a benzyl group, a phenylethyl group and a phenylpropyl group.
Examples of the hydrocarbon group which may contain an oxygen atom or a nitrogen atom include, for example, a divalent hydrocarbon group described below and the monovalent hydrocarbon group, which are ether bond, carbonyl bond, ester bond, amide bond, and imino. The group couple | bonded with at least 1 of a bond (-NH-) is mentioned.
The substituent that the monovalent hydrocarbon group represented by R ¹⁰ may have is not particularly limited as long as the effects of the present disclosure are not impaired, and examples thereof include a halogen atom such as a fluorine atom and a chlorine atom. , Hydroxyl group and the like.

The monovalent hydrocarbon group represented by R ¹⁰ is an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10 carbon atoms, from the viewpoint of improving flex resistance and compatibility of surface hardness. Preferably. The alkyl group having 1 to 3 carbon atoms is more preferably a methyl group, and the aryl group having 6 to 10 carbon atoms is more preferably a phenyl group.

Examples of the divalent hydrocarbon group represented by R ¹¹ include an alkylene group having 1 to 20 carbon atoms, an arylene group, and a combination thereof. The alkylene group may be linear, branched or cyclic, and may be linear or a combination of branched and cyclic.
The alkylene group having 1 to 20 carbon atoms is preferably an alkylene group having 1 to 10 carbon atoms, for example, straight chain such as methylene group, ethylene group, various propylene groups, various butylene groups, and cyclohexylene group. Examples of the group include a combination of a linear or branched alkylene group and a cyclic alkylene group.
The arylene group is preferably an arylene group having a carbon number of 6 to 12, and the arylene group includes a phenylene group, a biphenylene group, a naphthylene group, and the like, and further has a substituent for an aromatic ring described below. It may be.
As the divalent hydrocarbon group which may contain an oxygen atom or a nitrogen atom, the divalent hydrocarbon groups may be an ether bond, a carbonyl bond, an ester bond, an amide bond, and an imino bond (-NH-). There may be mentioned at least one bound group.
The substituent that the divalent hydrocarbon group represented by R ¹¹ may have is the same as the substituent that the monovalent hydrocarbon group represented by R ¹⁰ may have. Good.

The divalent hydrocarbon group represented by R ¹¹ is an alkylene group having 1 to 6 carbon atoms or an arylene group having 6 to 10 carbon atoms, from the viewpoint of improving flex resistance and compatibility of surface hardness. It is preferable that the alkylene group has 2 to 4 carbon atoms, and it is more preferable that the alkylene group has 2 to 4 carbon atoms.

Among them, a diamine residue having a silicon atom in the main chain is a diamine residue having one or two silicon atoms in the main chain, from the viewpoint of realizing a low retardation and improving compatibility of bending resistance and surface hardness. It is preferably a group.
The number of silicon atoms in the main chain of the diamine residue is not particularly limited, but it is preferably 1 or 2, and more preferably 2. This is because when the number of silicon atoms is 3 or more, the effect for realizing the low retardation is saturated, and the flexibility of the polyimide becomes too high, which may affect the heat resistance.

  Examples of the diamine having one silicon atom in the main chain include diamines represented by the following general formula (A-1). Moreover, as a diamine which has two silicon atoms in the main chain, the diamine represented by the following general formula (A-2) is mentioned, for example.

（一般式（Ａ−１）及び一般式（Ａ−２）において、Ｌはそれぞれ独立して、直接結合又は−Ｏ−結合であり、Ｒ^１０はそれぞれ独立して、置換基を有していても良く、酸素原子又は窒素原子を含んでいても良い炭素数１以上２０以下の１価の炭化水素基を表す。Ｒ^１１はそれぞれ独立して、置換基を有していても良く、酸素原子又は窒素原子を含んでいても良い炭素数１以上２０以下の２価の炭化水素基を表す。複数あるＬ、Ｒ^１０及びＲ^１１は、それぞれ同一であっても異なっていても良い。）

(In general formula (A-1) and general formula (A-2), L is a direct bond or -O- bond each independently, R < ¹⁰ > has a substituent each independently. Is a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain an oxygen atom or a nitrogen atom, and R ^11's each independently may have a substituent, and an oxygen atom. Or a divalent hydrocarbon group having 1 to 20 carbon atoms which may contain a nitrogen atom. A plurality of L, R ¹⁰ and R ¹¹ may be the same or different.)

From the viewpoint of achieving both low retardation and heat resistance, the molecular weight of the diamine residue having a silicon atom in the main chain is preferably 1000 or less, more preferably 800 or less, and further preferably 500 or less. It is preferably 300 or less, and particularly preferably 300 or less.
The molecular weight of the diamine residue is calculated by subtracting the molecular weight (32) of _two amino groups (—NH ₂ ) from the molecular weight of the diamine.
The diamine residue having a silicon atom in the main chain may be used alone or in combination of two or more.

  Further, the diamine having one or two silicon atoms in the main chain is preferably a diamine having two silicon atoms, from the viewpoint of light transmittance of the obtained polyimide, and bending resistance and surface hardness, Furthermore, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,3-bis (4-aminobutyl) tetramethyldisiloxane, 1,3-bis (5-aminopentyl) tetramethyldisiloxane, etc. However, it is preferable from the viewpoints of easy availability of these compounds and light transmittance of the obtained polyimide and surface hardness.

  When using a diamine having a silicon atom in the main chain, the proportion of the diamine having a silicon atom in the main chain is not particularly limited in the total amount of diamine, but from the viewpoint of reducing the retardation of the obtained polyimide film, 1 It is preferably at least mol%, more preferably at least 2.5 mol%, even more preferably at least 5 mol%. From the viewpoint of heat resistance of the obtained polyimide film, it is preferably 50 mol% or less, more preferably 45 mol% or less, more preferably 40 mol% or less, and 20 mol% or less. It is even more preferable to be present.

  Further, from the viewpoint that the surface hardness of the obtained polyimide is improved, when the total amount of the tetracarboxylic acid component and the diamine component is 100 mol%, the total amount of the tetracarboxylic acid having an aromatic ring and the diamine having an aromatic ring is It is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 75 mol% or more.

In the present disclosure, the polyimide may include an aromatic ring, and the (i) fluorine atom, (ii) aliphatic ring, and (iii) aromatic rings may be substituted with a sulfonyl group or fluorine. It is preferable that at least one selected from the group consisting of a structure linked by an alkylene group is included from the viewpoint of light transmittance and surface hardness. Furthermore, in addition to these structures, a diamine residue having a silicon atom in the main chain It is preferable to include a group in terms of low retardation and bending resistance.
In the present disclosure, the polyimide contains at least one selected from a tetracarboxylic acid residue having an aromatic ring and a diamine residue having an aromatic ring, whereby the molecular skeleton becomes rigid and the durability is increased, and the surface hardness is However, the rigid aromatic ring skeleton tends to have an absorption wavelength extending to a long wavelength, and the transmittance in the visible light region tends to decrease.
When (i) the fluorine atom is contained in the polyimide, it is possible to make it difficult for the electronic state in the polyimide skeleton to transfer charges, and thus the light transmittance is improved.
When the polyimide contains (ii) an aliphatic ring, the transfer of charges in the skeleton can be hindered by breaking the conjugation of π electrons in the polyimide skeleton, thereby improving the light transmittance.
When the polyimide includes (iii) a structure in which aromatic rings are linked to each other by a sulfonyl group or an alkylene group which may be substituted with fluorine, the transfer of charge in the skeleton can be prevented by cutting the π electron conjugation in the polyimide skeleton. The light transmittance is improved because it can be inhibited.

Among them, polyimide containing a fluorine atom is preferably used from the viewpoints of improving light transmittance and improving surface hardness.
The content ratio of fluorine atoms is preferably such that the ratio (F / C) of the number of fluorine atoms (F) and the number of carbon atoms (C) measured on the polyimide surface by X-ray photoelectron spectroscopy is 0.01 or more, Further, it is preferably 0.05 or more. On the other hand, if the content of fluorine atoms is too high, the heat resistance of the polyimide itself may decrease, so the ratio (F / C) of the number of fluorine atoms (F) and the number of carbon atoms (C) is 1 or less. Is preferable, and further preferably 0.8 or less.
Here, the above-mentioned ratio measured by X-ray photoelectron spectroscopy (XPS) can be determined from the atomic% value of each atom measured using an X-ray photoelectron spectrometer (for example, Theta Probe, Thermo Scientific). .

Further, from the viewpoint of surface hardness and light transmittance of the obtained polyimide, and from the viewpoint of bending resistance, at least one of tetracarboxylic acid and diamine having no silicon atom preferably contains an aromatic ring and a fluorine atom. Furthermore, it is preferable that both the tetracarboxylic acid and the diamine having no silicon atom include an aromatic ring and a fluorine atom.
From the viewpoint of the surface hardness and light transmittance of the obtained polyimide, and the resistance to bending, when the total amount of the tetracarboxylic acid component and the diamine component is 100 mol%, a tetracarboxylic acid having an aromatic ring and a fluorine atom, and The total amount of the diamine having an aromatic ring and a fluorine atom is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 75 mol% or more.

Further, 50% or more of hydrogen atoms bonded to carbon atoms contained in each of the tetracarboxylic acid component and the diamine component are hydrogen atoms directly bonded to the aromatic ring, which improves the light transmittance of the obtained polyimide. In addition, it is preferably used from the viewpoints of improving the surface hardness and bending resistance. The proportion of hydrogen atoms (number) directly bonded to the aromatic ring in all hydrogen atoms (number) bonded to carbon atoms is preferably 60% or more, more preferably 70% or more. ..
When 50% or more of the hydrogen atoms bonded to the carbon atoms contained in the tetracarboxylic acid component and the diamine component are hydrogen atoms bonded directly to the aromatic ring, even after a heating step in the atmosphere, for example, Even if stretching is carried out at 200 ° C. or higher, it is preferable from the standpoint that there is little change in optical characteristics, particularly the total light transmittance and the yellowness YI value, and the reduction in bending resistance is suppressed. When 50% or more of the hydrogen atoms bonded to the carbon atoms are hydrogen atoms directly bonded to the aromatic ring, the reactivity with oxygen is low, so that the chemical structure of the resulting polyimide is unlikely to change and oxidation may occur. It is estimated that the deterioration of the polyimide film is suppressed. Polyimide film uses its high heat resistance and is often used in devices that require a processing step involving heating, but 50% of hydrogen atoms bonded to carbon atoms contained in the tetracarboxylic acid component and diamine component are contained. If the above is a hydrogen atom that is directly bonded to the aromatic ring, it is not necessary to carry out these subsequent steps under an inert atmosphere to maintain transparency, so equipment costs and atmosphere control costs are reduced. There is a merit that it can be suppressed.
Here, the ratio of the hydrogen atoms (number) directly bonded to the aromatic ring in the total number of hydrogen atoms (number) bonded to the carbon atoms contained in the polyimide, the decomposition product of the polyimide, high performance liquid chromatography, gas chromatograph mass It can be determined using an analyzer and NMR. For example, a sample is decomposed with an alkaline aqueous solution or supercritical methanol, the obtained decomposed product is separated by high performance liquid chromatography, and a qualitative analysis of each separated peak is analyzed by a gas chromatograph mass spectrometer and NMR. The ratio of the hydrogen atoms (number) directly bonded to the aromatic ring in the total hydrogen atoms (number) contained in the polyimide can be determined by performing the measurement using high-performance liquid chromatography.

（一般式（１）において、Ｒ^１は芳香族環又は脂肪族環を有するテトラカルボン酸残基である４価の基を表し、Ｒ^２は、前記ジアミン残基である２価の基を表し、芳香族環又は脂肪族環を有するジアミン残基を含む。ｎは繰り返し単位数を表す。）The polyimide film according to the present disclosure preferably contains a polyimide having a structure represented by the following general formula (1) from the viewpoint of light transmission, heat resistance, and rigidity.

(In the general formula (1), R ¹ represents a tetravalent group which is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, and R ² represents a divalent group which is the diamine residue. , Including a diamine residue having an aromatic ring or an aliphatic ring, n represents the number of repeating units.)

As the tetracarboxylic dianhydride having an aromatic ring and the tetracarboxylic dianhydride having an aliphatic ring in R ^1, the same ones as described above can be used.
These may be used alone or in combination of two or more.

Among them, R ¹ in the general formula (1) is a cyclohexanetetracarboxylic acid dianhydride residue or a cyclopentanetetracarboxylic acid diacid from the viewpoint of light transmittance, bending resistance and surface hardness of the obtained polyimide. Anhydride residue, dicyclohexane-3,4,3 ', 4'-tetracarboxylic acid dianhydride residue, cyclobutanetetracarboxylic acid dianhydride residue, pyromellitic acid dianhydride residue, 3,3' , 4,4'-biphenyltetracarboxylic dianhydride residue, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride residue, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride Residue, 3,4 '-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene) diphthalic anhydride residue, 4,4'-oxydiphthalic acid residue Anhydride residue, and is preferably at least one tetravalent group selected from the group consisting of 3,4'-oxydiphthalic anhydride residue.

  In particular, the tetracarboxylic acid component is 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, 3,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, 3,3 from the viewpoint of good light transmittance. More preferably, it is at least one selected from the group consisting of '-(hexafluoroisopropylidene) diphthalic anhydride, 4,4'-oxydiphthalic anhydride, and 3,4'-oxydiphthalic anhydride.

Examples of the tetracarboxylic acid component include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride. A tetracarboxylic acid group (group A) suitable for improving rigidity of the resulting polyimide, such as at least one selected from the group consisting of compounds, cyclohexanetetracarboxylic dianhydride, and cyclopentanetetracarboxylic Acid dianhydride, dicyclohexane-3,4,3 ', 4'-tetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 3 , 4 '-(hexafluoroisopropylidene) diphthalic anhydride, 3,3'-(hexafluoroisopropylidene) diphthalic anhydride, 4,4 ' -Mixing with oxydiphthalic anhydride and at least one tetracarboxylic acid group (group B) suitable for improving light transmission selected from the group consisting of 3,4'-oxydiphthalic anhydride It is also preferable to use it. In this case, the content ratio of the tetracarboxylic acid group (group A) suitable for improving the rigidity and the tetracarboxylic acid group (group B) suitable for improving light transmittance is The amount of the tetracarboxylic acid group (group A) suitable for improving the rigidity is 0.05 mol or more and 9 mol or less with respect to 1 mol of the tetracarboxylic acid group (group B) suitable for improving The amount is preferably 0.1 mol or more and 5 mol or less, more preferably 0.3 mol or more and 4 mol or less.
Among them, as the group B, at least one of 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride and 3,4 ′-(hexafluoroisopropylidene) diphthalic anhydride containing a fluorine atom is used. Is preferable from the viewpoint of improving the light transmittance of the obtained polyimide.

In the general formula (1), R ² represents a divalent group which is a diamine residue, and is not particularly limited as long as it contains a diamine residue having an aromatic ring or an aliphatic ring. As the divalent diamine residue, the same ones as described above can be used.
These may be used alone or in combination of two or more.

As the diamine residue having an aromatic ring or an aliphatic ring contained in R ² , the same ones as described above can be used.
These may be used alone or in combination of two or more.

Among them, the diamine residue having an aromatic ring or an aliphatic ring represented by R ² in the general formula (1) is trans-, in terms of light transmittance and bending resistance, surface hardness, and low hygroscopicity. Cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4′-diaminodiphenylsulfone residue, 3,4′-diaminodiphenylsulfone residue, 2,2-bis (4-aminophenyl) ) Propane residue, 3,3'-bis (trifluoromethyl) -4,4 '-[(1,1,1,3,3,3-hexafluoropropane-2,2-diyl) bis (4 1-phenyleneoxy)] dianiline residue, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, 2,2-bis [4- (4 Aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, and at least one 2 selected from the group consisting of divalent groups represented by the following general formula (2). It is preferably a valent group. As the divalent group represented by the following general formula (2), it is more preferable that R ³ and R ⁴ are perfluoroalkyl groups.

（一般式（２）において、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子、アルキル基、またはパーフルオロアルキル基を表す。）
これらは単独でも、２種以上を混合して用いることもできる。

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.)
These may be used alone or in combination of two or more.

Further, from the viewpoint of reducing the retardation, it is preferable that R ² contains a diamine residue having a silicon atom in the main chain. The diamine residue having a silicon atom in the main chain that can be preferably used as R ² is as described above, and therefore the description thereof is omitted here.

When containing a diamine residue having a silicon atom in the main chain as ^{R 2} in the general formula (1), in ^{R 2} in the general formula (1), 2.5 mol% to 50 mol of the total amount of ^{R 2} % Or less is a diamine residue having a silicon atom in the main chain, and 50 mol% or more and 97.5 mol% or less of the total amount of R ² does not have a silicon atom and has an aromatic ring or an aliphatic ring. The use of a diamine residue is preferable because the retardation can be reduced and the protective film can have sufficient surface hardness. From the viewpoint of reducing the retardation, R ^{2 in the} general formula (1) preferably has a diamine residue having a silicon atom in the main chain in an amount of 3.5 mol% or more of the total amount of R ² , and further 5 It is preferably at least mol%. R ² of the general formula (1) may have a diamine residue having a silicon atom in the main chain in an amount of 10 mol% or more, and further 20 mol% or more of the total amount of R ² from the viewpoint of reducing the retardation. good. On the other hand, in R ² of the general formula (1), the diamine residue having a silicon atom in the main chain is 45 mol% or less of the total amount of R ² from the viewpoint of improving surface hardness and light transmittance. It is preferably 40 mol% or less.
Incidentally, 50 mol% 2.5 mol% or more of the total amount of ^{R 2} or less, a diamine residue having a silicon atom in the main chain, or less 97.5 mol% 50 mol% or more of the total amount of ^{R 2,} silicon R ² of the general formula (1) may include a diamine residue having a silicon atom in the main chain and a silicon atom if it is a diamine residue having no atom but an aromatic ring or an aliphatic ring. It does not prevent inclusion of another diamine residue which is different from the diamine residue having no aromatic ring or an aliphatic ring. The other diamine residue is preferably 10 mol% or less of the total amount of R ² , more preferably 5 mol% or less, still more preferably 3 mol% or less, and particularly 1 mol%. The following is preferable. Examples of the other diamine residue include a diamine residue having no silicon atom and having no aromatic ring or aliphatic ring.
Among them, more than 2.5 mol% of the total amount of R ² 50 mol% or less, a diamine residue having a silicon atom in the main chain, of the total amount of R ² (100 mol%), silicon atoms in the main chain 50 mol% or more and 99 mol% or less, which is the remaining (100% -x%) of the mol% (x mol%) of the diamine residue having, has no silicon atom and has an aromatic ring or an aliphatic ring. It is preferably a diamine residue.

Among them, R ² in the general formula (1) is a diamine residue having no silicon atom, and silicon in the main chain, from the viewpoint of reducing the retardation and improving both flex resistance and surface hardness. It represents a divalent group that is at least one selected from diamine residues having one or two atoms, and 2.5 mol% or more and 50 mol% or less of the total amount of R ² contains 1 silicon atom in the main chain. It is preferable that 50 or more and 97.5 mol% or less is a diamine residue having one or two diamine residues, which has no silicon atom and has an aromatic ring or an aliphatic ring.
Among them, 50 mole% 2.5 mol% or more of the total amount of ^{R 2} or less is a main one silicon atom in a chain or two with diamine residue, of the total amount of ^{R 2} (100 mol%), the 50 mol% or more and 97.5 mol% or less, which is the remaining (100% -x%) of the mol% (x mol%) of the diamine residue having one or two silicon atoms in the main chain, has a silicon atom. First, it is preferably a diamine residue having an aromatic ring or an aliphatic ring.
R ² of the general formula (1) is a diamine residue having one or two silicon atoms in the main chain of 3 in the total amount of R ² in order to reduce the retardation and improve the bending resistance. It is preferably at least mol%, more preferably at least 5 mol%, and the diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring may be R ² corresponding to the above. Is preferably 97 mol% or less, and more preferably 95 mol% or less.
R ² of the general formula (1) is a diamine residue having one or two silicon atoms in the main chain, from the viewpoint of reducing the phase difference, 10 mol% or more, further 20 mol% of the total amount of R ^2. Or more, and in this case, the diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring is 90 mol% or less of the total amount of R ² , further 80 mol, corresponding to the above. % Or less.
On the other hand, R ^{2 in the} general formula (1) is a diamine residue having one or two silicon atoms in the main chain, which is R in order to improve surface hardness and light transmittance while reducing the phase difference. It is preferably 45 mol% or less, more preferably 40 mol% or less of the total amount of ² , and the diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring corresponds to the above. Therefore, the total amount of R ² is preferably 55 mol% or more, and more preferably 60 mol% or more.

In the structure represented by the general formula (1), n represents the number of repeating units and is 1 or more.
The number of repeating units n in the polyimide may be appropriately selected and is not particularly limited.
The average number of repeating units is usually 10 to 2000, preferably 15 to 1000.
In addition, R ¹ in each repeating unit may be the same or different, and R ² in each repeating unit may be the same or different.

The polyimide having the structure represented by the general formula (1) preferably has a number average molecular weight of 10,000 or more, and more preferably 20,000 or more, from the viewpoint of strength and bending resistance when formed into a film. It is more preferably 30,000 or more, still more preferably 50,000 or more. Although the upper limit is not particularly limited, it is preferably 10,000,000 or less, more preferably 500000 or less, from the viewpoint of easy synthesis and easy availability.
The number average molecular weight of the polyimide can be measured in the same manner as the number average molecular weight of the polyimide precursor described later.

The weight average molecular weight of the polyimide having the structure represented by the general formula (1) is preferably 20,000 or more, and more preferably 30,000 or more, from the viewpoint of strength and bending resistance when formed into a film. It is more preferably 40,000 or more, still more preferably 80,000 or more. Although the upper limit is not particularly limited, it is preferably 10,000,000 or less, more preferably 500000 or less, from the viewpoint of easy synthesis and easy availability.
The weight average molecular weight of polyimide can be measured by gel permeation chromatography (GPC). Specifically, polyimide was used as an N-methylpyrrolidone (NMP) solution having a concentration of 0.1% by weight, a developing solvent was a 30 mmol% LiBr-NMP solution having a water content of 500 ppm or less, and a Tosoh GPC device (HLC- 8120, column used: GPC LF-804 manufactured by SHODEX, and measurement is performed under the conditions of a sample injection amount of 50 μL, a solvent flow rate of 0.4 mL / min, and 37 ° C. The weight average molecular weight is determined based on a polystyrene standard sample having the same concentration as the sample.

The polyimide used in the present disclosure may have a part of a structure different from polyimide, such as a polyamide structure, as long as the effect of the present disclosure is not impaired.
The polyimide used in the present disclosure may have a part of the structure different from the structure represented by the general formula (1) as long as the effect of the present disclosure is not impaired. In the polyimide used in the present disclosure, the structure represented by the general formula (1) is preferably 95% or more, more preferably 98% or more, and more preferably 100% of the total number of repeating units of the polyimide. It is even more preferable to be present.
Examples of the structure different from the structure represented by the general formula (1) include a case where a tetracarboxylic acid residue having no aromatic ring or an aliphatic ring is contained, or a polyamide structure.
Examples of the polyamide structure that may be included include a polyamideimide structure containing a tricarboxylic acid residue such as trimellitic anhydride, and a polyamide structure containing a dicarboxylic acid residue such as terephthalic acid.

  The content ratio of each repeating unit in the polyimide and the content ratio (mol%) of each tetracarboxylic acid residue or each diamine residue can be determined from the molecular weight charged during the production of the polyimide. Further, the content ratio (mol%) of each tetracarboxylic acid residue and each diamine residue in the polyimide is, similarly to the above, an alkaline aqueous solution, or about the decomposed product of the polyimide obtained by decomposition with supercritical methanol , High performance liquid chromatography, gas chromatograph mass spectrometer, NMR, elemental analysis, XPS / ESCA and TOF-SIMS.

2. Additive The polyimide film of the present disclosure may further contain an additive, if necessary, in addition to the polyimide. Examples of the additive include inorganic particles, a silica filler for smoothing winding, and a surfactant for improving film-forming property and defoaming property.

3. Characteristics of Polyimide Film The tan δ curve and the total light transmittance in the polyimide film of the present disclosure have been described above, and thus the description thereof is omitted here.

Moreover, the retardation is reduced in the polyimide film of the present disclosure. Since the measured value of the retardation is affected by the film thickness, it may not be possible to evaluate the superiority or inferiority of the retardation of the polyimide film only by the measured value.Therefore, it is usually calculated by dividing the retardation by the film thickness. The refractive index is converted and evaluated.
In the polyimide film of the present disclosure, the birefringence index in the film thickness direction at a wavelength of 590 nm is preferably smaller, and more preferably less than 0.008, further preferably 0.005 or less, and 0. It is even more preferably 004 or less.
The polyimide film of the present disclosure in which the retardation is reduced can suppress the deterioration of the display quality of the display when used as a surface material for a display.
The retardation and birefringence in the film thickness direction of the polyimide film of the present disclosure at a wavelength of 590 nm can be obtained as follows.
First, using a phase difference measuring device (for example, manufactured by Oji Scientific Instruments Co., Ltd., product name “KOBRA-WR”), the phase difference value (Rth) in the film thickness direction of the polyimide film is measured at 25 ° C. with light having a wavelength of 590 nm. taking measurement. As the film thickness direction retardation value (Rth), the phase difference value of 0 degree incidence and the phase difference value of oblique 40 degree incidence are measured, and the film thickness direction retardation value Rth is calculated from these phase difference values. The retardation value at an incident angle of 40 degrees is measured by allowing light having a wavelength of 590 nm to enter the retardation film from a direction inclined by 40 degrees from the normal line of the retardation film.
The birefringence index in the film thickness direction of the polyimide film can be determined by substituting it into the formula: Rth / d. The d represents the film thickness (nm) of the polyimide film.
In the film thickness direction retardation value, the refractive index in the slow axis direction in the in-plane direction of the film (direction in which the refractive index in the in-plane direction is the maximum) is nx, and the fast axis direction in the film plane (film Rth [nm] = {(nx + ny) / 2−nz} × d, where ny is the refractive index in the direction in which the refractive index in the in-plane direction is the minimum) and nz is the refractive index in the film thickness direction of the film. It can be expressed as.

Further, the polyimide film of the present disclosure preferably has a yellowness index (YI value) of 30 or less calculated according to JIS K7373-2006. When the degree of yellowness (YI value) is 30 or less, yellowing is suppressed, light transmission is improved, and a good glass substitute material can be obtained. The yellowness index (YI value) calculated according to JIS K7373-2006 is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less.
The polyimide film of the present disclosure has a thickness of 5 μm or more and 100 μm or less, and a yellowness index (YI value) calculated according to JIS K7373-2006 is preferably 30 or less, more preferably 20 or less, It is more preferably 15 or less, and particularly preferably 10 or less.
In the polyimide film of the present disclosure, the yellowness (YI value) calculated according to JIS K7373-2006 at a thickness of 50 μm ± 5 μm is preferably 10 or less, and more preferably 7 or less. It is more preferably 5 or less.
Note that the yellowness (YI value) is based on JIS K7373-2006, using an ultraviolet-visible near-infrared spectrophotometer (for example, JASCO Corporation V-7100), and by a spectrocolorimetric method, an auxiliary illuminant. C, tristimulus values X, Y, Z in the XYZ color system are obtained based on the transmittance measured at intervals of 1 nm in a range of 250 nm to 800 nm using a 2 degree visual field. It can be calculated from the value of Z by the following formula.
YI = 100 (1.2769X-1.0592Z) / Y
In addition, from the measured value of the yellowness of a certain thickness, the yellowness of the different thickness is the above-mentioned total transmittance for each wavelength measured at 1 nm intervals between 250 nm and 800 nm of a sample having a certain film thickness. Similar to the light transmittance, the converted value of each transmittance at each wavelength of different thickness can be obtained by Lambert-Beer's law, and the converted value can be calculated and used.

The haze value of the polyimide film of the present disclosure is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.0 or less from the viewpoint of light transmittance. It is preferable that the haze value can be achieved when the thickness of the polyimide film is 5 μm or more and 100 μm or less.
The haze value can be measured by a method according to JIS K-7105, and can be measured, for example, by a haze meter HM150 manufactured by Murakami Color Research Laboratory.

In addition, the polyimide film of the present disclosure has a tensile elastic modulus at 25 ° C. of a 15 mm × 40 mm test piece measured at a pulling speed of 8 mm / min and a chuck-to-chuck distance of 20 mm according to JIS K7127. It is preferably 1.8 GPa or more, and may be 5.0 GPa or less from the viewpoint of bending resistance. From the viewpoint of bending resistance and surface hardness, it is more preferably 2.0 GPa or more and 4.0 GPa or less, and further preferably 2.0 GPa or more and 3.5 GPa or less.
The tensile modulus is measured at 25 ° C. by using a tensile tester (for example, Shimadzu Corporation: Autograph AG-X 1N, load cell: SBL-1KN) to cut a test piece having a width of 15 mm and a length of 40 mm from a polyimide film. The pulling speed is 8 mm / min, and the chuck distance is 20 mm. The thickness of the polyimide film for obtaining the tensile elastic modulus is preferably 55 μm ± 5 μm.

In the polyimide film of the present disclosure, the pencil hardness may be 6B or higher, but from the viewpoint of surface hardness, B or higher is more preferable, and HB or higher is still more preferable.
The pencil hardness of the polyimide film is measured according to JIS K5600-5-4 using a test pencil defined by JIS-S-6006 after conditioning a measurement sample at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours. It can be performed by performing a pencil hardness test (0.98 N load) defined in (1999) on the film surface and evaluating the highest pencil hardness without scratches. As the testing machine, for example, a pencil scratch coating hardness tester manufactured by Toyo Seiki Co., Ltd. can be used.

4. Configuration of Polyimide Film The thickness of the polyimide film of the present disclosure may be appropriately selected depending on the application, but from the viewpoint of strength, it is preferably 1 μm or more, more preferably 5 μm or more, further more 10 μm or more. Is preferred.

  In addition, the polyimide film of the present disclosure may be subjected to surface treatment such as saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet treatment, and flame treatment.

5. Method for producing polyimide film The method for producing the polyimide film of the present disclosure is not particularly limited as long as it is a method capable of producing the polyimide film of the present disclosure. Is preferable, and the following first production method is preferable.
<First manufacturing method>
As the method for producing the polyimide film of the present disclosure, as the first production method,
Polyamic acid that is a polyimide precursor, and a step of preparing a polyimide precursor resin composition containing an organic solvent (hereinafter, referred to as polyimide precursor resin composition preparation step),
A step of applying the polyimide precursor resin composition to a support to form a polyimide precursor resin coating film (hereinafter referred to as a polyimide precursor resin coating film forming step),
A method for producing a polyimide film includes a step of imidizing the polyimide precursor by heating (hereinafter referred to as a thermal imidization step).

In the method for producing a polyimide film of the present disclosure, further, a step of stretching at least one of the polyimide precursor resin coating film, and, after imidization of the polyimide precursor resin coating film after imidization (hereinafter, stretching Referred to as a process).
Hereinafter, an example of the method for producing a polyimide film of the present disclosure having a thermal imidization step will be described in detail for each step.

(1) Polyimide precursor resin composition preparation step The polyimide precursor resin composition contains a polyimide precursor and an organic solvent, and may contain additives and the like as necessary. Examples of the polyimide precursor include a polyimide precursor represented by the following general formula (1 ′). The polyimide precursor represented by the general formula (1 ′) includes a tetracarboxylic acid component serving as a tetracarboxylic acid residue in R ¹ of the general formula (1 ′) and R ^{2 of the} general formula (1 ′). Is a polyamic acid obtained by polymerization with a diamine component to be a diamine residue in the above.

（一般式（１’）において、Ｒ^１、Ｒ^２及びｎは、前記一般式（１）と同様である。）

(In the general formula (1 ′), R ¹ , R ² and n are the same as those in the general formula (1).)

In the polyimide precursor represented by the general formula (1 ′), at least one of the number average molecular weight and the weight average molecular weight is preferably 10,000 or more from the viewpoint of strength when formed into a film, and further 20000. The above is preferable. On the other hand, when the average molecular weight is too large, the viscosity becomes high and workability such as filtration may be deteriorated, so that it is preferably 10,000,000 or less, and more preferably 500000 or less.
The number average molecular weight of the polyimide precursor can be determined by NMR (for example, AVANCEIII manufactured by BRUKER). For example, a polyimide precursor solution is applied to a glass plate and dried at 100 ° C. for 5 minutes, then 10 mg of solid content is dissolved in 7.5 ml of dimethylsulfoxide-d6 solvent, NMR measurement is performed, and it is bonded to an aromatic ring. The number average molecular weight can be calculated from the peak intensity ratio of hydrogen atoms.
The weight average molecular weight of the polyimide precursor can be measured by gel permeation chromatography (GPC).
The polyimide precursor is an N-methylpyrrolidone (NMP) solution having a concentration of 0.5% by weight, a developing solvent is a 10 mmol% LiBr-NMP solution having a water content of 500 ppm or less, and a Tosoh GPC device (HLC-8120, used) Column: GPC LF-804 manufactured by SHODEX) is used, and measurement is performed under the conditions of a sample injection amount of 50 μL, a solvent flow rate of 0.5 mL / min, and 40 ° C. The weight average molecular weight is determined based on a polystyrene standard sample having the same concentration as the sample.

  The polyimide precursor solution is obtained by reacting the above tetracarboxylic dianhydride and the above diamine in a solvent. The solvent used in the synthesis of the polyimide precursor (polyamic acid) is not particularly limited as long as it can dissolve the above-mentioned tetracarboxylic dianhydride and diamine, for example, aprotic polar solvent or water-soluble alcohol solvent or the like. Can be used. In the present disclosure, among others, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone, etc. It is preferable to use an organic solvent containing a nitrogen atom; γ-butyrolactone or the like. Among them, when the polyimide precursor solution (polyamic acid solution) is used as it is for the preparation of the polyimide precursor resin composition, when the polyimide precursor resin composition contains the inorganic particles described below, the dissolution of the inorganic particles is suppressed. From this point, it is preferable to use an organic solvent containing a nitrogen atom, and it is particularly preferable to use N, N-dimethylacetamide, N-methyl-2-pyrrolidone, or a combination thereof. The organic solvent is a solvent containing carbon atoms.

Further, when the polyimide precursor solution is prepared by combining two or more kinds of diamines, acid dianhydride may be added to a mixed solution of at least two kinds of diamines to synthesize a polyamic acid, At least two kinds of diamine components may be added to the reaction solution stepwise at an appropriate molar ratio to control the sequence in which each raw material is incorporated into the polymer chain to some extent.
For example, by adding an acid dianhydride in a molar ratio of 0.5 equivalent of a diamine having a silicon atom in the main chain to a reaction solution in which a diamine having a silicon atom in the main chain is reacted, Synthesize an amic acid reacted with a diamine having a silicon atom in the main chain on both ends of the anhydride, there, all or part of the remaining diamine, the acid dianhydride was added to polymerize the polyamic acid. Is also good. When polymerized by this method, a diamine having a silicon atom in the main chain is introduced into a polyamic acid in a linked form via one acid dianhydride.
It is preferable to polymerize the polyamic acid by such a method because the positional relationship of the amic acid having a silicon atom in the main chain is specified to some extent, and it is easy to obtain a film having a low retardation while maintaining the surface hardness.

When the number of moles of diamine in the polyimide precursor solution (polyamic acid solution) is X and the number of moles of tetracarboxylic dianhydride is Y, Y / X may be 0.9 or more and 1.1 or less. It is preferably 0.95 or more and 1.05 or less, more preferably 0.97 or more and 1.03 or less, and particularly preferably 0.99 or more and 1.01 or less. The molecular weight (degree of polymerization) of the obtained polyamic acid can be appropriately adjusted by setting it in such a range.
A known method can be appropriately selected and used as the procedure of the polymerization reaction and is not particularly limited.
Alternatively, the polyimide precursor solution obtained by the synthesis reaction may be used as it is, and other components may be mixed therein as necessary, or the solvent of the polyimide precursor solution may be dried and dissolved in another solvent. You may use.

The viscosity of the polyimide precursor solution at 25 ° C. is preferably 500 cps or more and 200,000 cps or less from the viewpoint of forming a uniform coating film and a polyimide film.
The viscosity of the polyimide precursor solution can be measured at 25 ° C. using a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.).

  The polyimide precursor resin composition may contain an additive as needed. Examples of the additive include a silica filler for facilitating winding, a surfactant for improving film-forming property and defoaming property, and the same as those described in the above-mentioned polyimide film. Can be used.

  The organic solvent used in the polyimide precursor resin composition is not particularly limited as long as the polyimide precursor can be dissolved. For example, it contains a nitrogen atom such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, and 1,3-dimethyl-2-imidazolidinone. Organic solvent: γ-butyrolactone or the like can be used, but among them, it is preferable to use an organic solvent containing a nitrogen atom for the reason described above.

The content of the polyimide precursor in the polyimide precursor resin composition is 50% by mass or more in the solid content of the resin composition from the viewpoint of forming a polyimide film having a uniform coating film and a handleable strength. It is preferable that the amount is 60% by mass or more, and the upper limit may be appropriately adjusted depending on the contained components.
From the viewpoint of forming a uniform coating film and a polyimide film, the organic solvent in the polyimide precursor resin composition is preferably 40% by mass or more, and more preferably 50% by mass or more in the resin composition. It is preferably 99% by mass or less.

In addition, the polyimide precursor resin composition preferably has a water content of 1000 ppm or less from the viewpoint that the storage stability of the polyimide precursor resin composition is good and the productivity can be improved. If the polyimide precursor resin composition contains a large amount of water, the polyimide precursor may be easily decomposed.
The water content of the polyimide precursor resin composition can be determined using a Karl Fischer moisture meter (for example, Mitsubishi Chemical Corporation, trace moisture measuring device CA-200 type).

The viscosity of the polyimide precursor resin composition at a solid content of 15% by mass at 25 ° C. is preferably 500 cps or more and 100000 cps or less from the viewpoint of forming a uniform coating film and a polyimide film.
The viscosity of the polyimide precursor resin composition can be measured with a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.) at 25 ° C. as a sample amount of 0.8 mL.

(2) Polyimide precursor resin coating film forming step In the step of applying the polyimide precursor resin composition to a support to form a polyimide precursor resin coating film, the support used has a smooth surface and heat resistance. There is no particular limitation as long as it is a material having solvent resistance and solvent resistance. Examples thereof include an inorganic material such as a glass plate and a metal plate whose surface is mirror-finished. The shape of the support is selected depending on the coating method and may be, for example, a plate shape, a drum shape, a belt shape, a sheet shape that can be wound into a roll, or the like.

The coating means is not particularly limited as long as it is a method capable of coating with a target film thickness, and known materials such as a die coater, a comma coater, a roll coater, a gravure coater, a curtain coater, a spray coater and a lip coater can be used. ..
The coating may be performed by a single-wafer type coating device or a roll-to-roll type coating device.

  After the polyimide precursor resin composition is applied to the support, the solvent in the coating film is dried at a temperature of 150 ° C. or lower, preferably 30 ° C. or higher and 120 ° C. or lower, until the coating film becomes tack-free. By setting the drying temperature of the solvent to 150 ° C. or lower, imidization of polyamic acid can be suppressed.

  The drying time may be appropriately adjusted according to the film thickness of the polyimide precursor resin coating film, the type of solvent, the drying temperature, etc., but is usually 1 minute to 60 minutes, preferably 2 minutes to 30 minutes. When it exceeds the upper limit, it is not preferable from the viewpoint of production efficiency of the polyimide film. On the other hand, when the amount is less than the lower limit value, the appearance of the obtained polyimide film may be affected by the rapid drying of the solvent.

The method for drying the solvent is not particularly limited as long as the solvent can be dried at the above temperature, and for example, an oven, a drying furnace, a hot plate, infrared heating or the like can be used.
When a high degree of control of optical properties is required, the atmosphere during drying of the solvent is preferably an inert gas atmosphere. The inert gas atmosphere is preferably a nitrogen atmosphere, the oxygen concentration is preferably 100 ppm or less, and more preferably 50 ppm or less. When the heat treatment is performed in the atmosphere, the film may be oxidized and may be colored or the performance may be deteriorated.

(3) Thermal Imidization Step In the method for producing a polyimide film of the present disclosure, it is preferable to imidize by heating. As described above, in thermal imidization, a film is formed in the state of a polyimide precursor to form an imidized film, but in the state of being formed into a film, the amide bond of the polyimide precursor is bent due to the effect of the movement of the molecular chain due to heat. Therefore, the polymer chain in the obtained polyimide is likely to have a bent molecular structure.
Therefore, in the tan δ curve, in order to obtain a polyimide film having a maximum value of tan δ of 0.18 or more in a temperature range of the temperature on the high temperature side minimum value of the first peak or more and 500 ° C. or less, imidization is performed by the thermal imidization step. It is preferable to carry out.
In the manufacturing method, in the case of having a stretching step, the thermal imidization step may be performed on the polyimide precursor in the polyimide precursor resin coating film before the stretching step, or the polyimide precursor after the stretching step. It may be performed for the polyimide precursor in the resin coating film, for both the polyimide precursor in the polyimide precursor resin coating film before the stretching step and the polyimide precursor present in the film after the stretching step. You may go.

The temperature of the imidization is such that the polymer chains in the resulting polyimide tend to have a bent-shaped molecular structure, that is, the polymer chains in the polyimide precursor tend to have a bent-shaped molecular structure. It may be appropriately selected according to the above.
Usually, the temperature rising start temperature is preferably 30 ° C. or higher, more preferably 100 ° C. or higher. On the other hand, the temperature rising end temperature is preferably 250 ° C. or higher.

It is preferable to appropriately select the heating rate according to the film thickness of the obtained polyimide film, and when the polyimide film has a large film thickness, it is preferable to slow the heating rate.
From the viewpoint of the production efficiency of the polyimide film, it is preferably 5 ° C./minute or more. On the other hand, the upper limit of the rate of temperature increase is usually 50 ° C./min or less, preferably 40 ° C./min or less, more preferably 30 ° C./min or less. The above rate of temperature increase is preferable from the viewpoint that the appearance of the film can be suppressed from being deteriorated and that the strength can be suppressed, whitening due to the imidization reaction can be controlled, and the light transmittance can be improved.

  The temperature increase may be continuous or stepwise, but it is preferable to make it continuous because the polymer chain in the obtained polyimide tends to have a bent molecular structure. In addition, the rate of temperature increase may be constant or may be changed in the middle of the above entire temperature range.

The atmosphere during the temperature rise of imidization is preferably an inert gas atmosphere. The inert gas atmosphere is preferably a nitrogen atmosphere, the oxygen concentration is preferably 500 ppm or less, more preferably 200 ppm or less, further preferably 100 ppm or less. When the heat treatment is performed in the atmosphere, the film may be oxidized and may be colored or the performance may be deteriorated.
However, when 50% or more of the hydrogen atoms bonded to the carbon atoms contained in the polyimide are hydrogen atoms directly bonded to the aromatic ring, the influence of oxygen on the optical properties is small, and it is not necessary to use an inert gas atmosphere. Also, a polyimide having high light transmittance can be obtained.

  The heating method for imidization is not particularly limited as long as the temperature can be raised at the above temperature, and for example, an oven, a heating furnace, infrared heating, electromagnetic induction heating or the like can be used.

Above all, it is more preferable to set the imidization ratio of the polyimide precursor to 50% or more before the stretching step. By setting the imidization ratio to 50% or more before the stretching step, stretching is performed after the step, and then heating is performed at a higher temperature for a certain period of time to imidize the film, and the appearance of the film may be poor. Whitening is suppressed. Above all, from the viewpoint that the surface hardness of the polyimide film is improved, it is preferable to set the imidization rate to 80% or more in the imidization step before the stretching step, and to advance the reaction to 90% or more, and further 100%. Is preferred. By stretching after imidization, it is presumed that the surface hardness is improved because the rigid polymer chains are easily oriented.
The imidization ratio can be measured by spectrum analysis by infrared measurement (IR).

In order to obtain the final polyimide film, it is preferable that the imidization proceeds to 90% or more, further 95% or more, and further 100%.
In order to advance the reaction to 90% or more of imidization, and further to 100%, it is preferable to hold at the temperature rising end temperature for a certain time, and the holding time is usually 1 minute to 180 minutes, further 5 minutes to 150 minutes. It is preferable to set it as minutes.

<Second manufacturing method>
The method for producing a polyimide film of the present disclosure, in the tan δ curve, if it is possible to obtain a polyimide film having a maximum value of tan δ of 0.18 or more in a temperature range of the high temperature side minimum value of the first peak or more and 500 ° C. or less, The following second manufacturing method may be used.
As a method for manufacturing the polyimide film of the present disclosure, as a second manufacturing method,
Polyimide, a step of preparing a polyimide resin composition containing an organic solvent (hereinafter referred to as a polyimide resin composition preparation step),
A method for producing a polyimide film includes a step of applying the polyimide resin composition to a support and drying a solvent to form a polyimide resin coating film (hereinafter referred to as a polyimide resin coating film forming step).

  When the polyimide has solvent solubility such that it dissolves in an organic solvent at 25 ° C. in an amount of 5% by mass or more, the manufacturing method can be preferably used.

  In the polyimide resin composition preparation step, the above-mentioned polyimide having solvent solubility can be selected and used from the same polyimides as those described in the polyimide film. As a method of imidization, it is preferable to use chemical imidization performed by using a chemical imidizing agent in place of heat dehydration in the dehydration ring closure reaction of the polyimide precursor. When performing chemical imidization, known compounds such as amines such as pyridine and β-picolinic acid, carbodiimides such as dicyclohexylcarbodiimide, and acid anhydrides such as acetic anhydride may be used as the dehydration catalyst. The acid anhydride is not limited to acetic anhydride, and examples thereof include propionic acid anhydride, n-butyric acid anhydride, benzoic acid anhydride and trifluoroacetic acid anhydride, but are not particularly limited. At that time, a tertiary amine such as pyridine or β-picolinic acid may be used together. However, when these amines remain in the film, optical properties, particularly yellowness (YI value), are reduced, so that the reaction liquid reacted from the precursor to the polyimide is cast as it is to form a film. It is preferable to purify by reprecipitation or the like, remove components other than polyimide to 100 ppm or less of the total weight of polyimide, and then form a film.

  In the polyimide resin composition preparation step, as the organic solvent used in the reaction liquid for chemically imidizing the polyimide precursor, for example, those described in the polyimide precursor resin composition preparation step in the first production method, The same can be used. In the polyimide resin composition preparation step, as the organic solvent used when redissolving the purified polyimide from the reaction solution, for example, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol mono-normal-butyl ether, Ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ortho-dichlorobenzene, xylene, cresol, chlorobenzene, isobutyl acetate, isopentyl acetate, normal-butyl acetate, normal-propyl acetate, normal-pentyl acetate, cyclohexanol, cyclohexanone, 1.4-dioxane, tetrachloroethylene, toluene, methyl isobutyl ketone, methyl cyclohexanol, methyl cyclohexyl Sanone, methyl-normal-butyl ketone, dichloromethane, dichloroethane and mixed solvents thereof, and the like, among them, at least one selected from the group consisting of dichloromethane, normal-butyl acetate, propylene glycol monomethyl ether acetate and mixed solvents thereof. It can be preferably used.

The polyimide resin composition may contain an additive as needed. As the additive, the same ones as described in the polyimide precursor resin composition preparing step in the first manufacturing method can be used.
Further, in the second manufacturing method, as a method of setting the water content of the polyimide resin composition to 1000 ppm or less, and a method of dispersing the inorganic particles in an organic solvent, the polyimide precursor in the first manufacturing method is used. The same method as the method described in the resin composition preparing step can be used.

In the polyimide resin coating film forming step in the second manufacturing method, the same support and coating method as those described in the polyimide precursor resin coating film forming step in the first manufacturing method are used. be able to.
In the polyimide resin coating film forming step in the second manufacturing method, the drying temperature is preferably 80 ° C. or higher and 150 ° C. or lower under normal pressure. Under reduced pressure, the temperature is preferably in the range of 10 ° C or higher and 100 ° C or lower.

Moreover, the said 2nd manufacturing method may have the process of further heating a polyimide resin coating film from the point of volatilizing the residual solvent after the said polyimide resin coating film formation process. Having such a heating step is preferable from the viewpoint of improving the film strength and chemical resistance.
The heating step can be the same as the imidation step by heating in the first manufacturing method.

  Further, the second manufacturing method may include a stretching step of stretching the polyimide resin coating film after the polyimide resin coating film forming step. The stretching step can be the same as the stretching step in the first manufacturing method.

6. Use of Polyimide Film The use of the polyimide film of the present disclosure is not particularly limited, and the polyimide film can be used as a member such as a base material or a surface material that has been conventionally used for glass products such as thin plate glass. Since the polyimide film of the present disclosure is excellent in transparency and has a low phase, it can be suitably used as a surface material for a display, particularly as a surface material for a large display.
Further, the polyimide film of the present disclosure is used for a member for an image display device such as a liquid crystal display device or an organic EL display device, a member for a touch panel, a flexible printed circuit board, a member for a solar cell panel such as a surface protective film or a substrate material, an optical waveguide. It can also be applied to members for semiconductors and other semiconductor-related members.

II. Laminate A laminate of the present disclosure is a laminate having the above-described polyimide film of the present disclosure and a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound.
Since the laminate of the present disclosure uses the polyimide film of the present disclosure described above, it has excellent transparency and has a reduced retardation.

1. Polyimide Film As the polyimide film used in the laminate of the present disclosure, the above-described polyimide film of the present disclosure can be used, and thus the description thereof is omitted here.

2. Hard coat layer The hard coat layer used for the laminate of the present disclosure contains at least one polymer of a radically polymerizable compound and a cationically polymerizable compound.

(1) Radical Polymerizable Compound The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group contained in the radical polymerizable compound is not particularly limited as long as it is a functional group capable of causing a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond, and the like. Specific examples thereof include a vinyl group and a (meth) acryloyl group. When the radical-polymerizable compound has two or more radical-polymerizable groups, these radical-polymerizable groups may be the same or different.

The number of radically polymerizable groups contained in one molecule of the radically polymerizable compound is preferably 2 or more, and more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer.
From the viewpoint of high reactivity, the radically polymerizable compound is preferably a compound having a (meth) acryloyl group, and a polyfunctional acrylate monomer having 2 to 6 (meth) acryloyl groups in one molecule. Preferred compounds and oligomers having urethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate having several (meth) acryloyl groups in the molecule and having a molecular weight of several hundred to several thousand are preferred. Can be used.
In addition, in this specification, (meth) acryloyl represents each of acryloyl and methacryloyl, and (meth) acrylate represents each of acrylate and methacrylate.

  Specific examples of the radically polymerizable compound include vinyl compounds such as divinylbenzene; ethylene glycol di (meth) acrylate, bisphenol A epoxy di (meth) acrylate, 9,9-bis [4- (2- ( (Meth) acryloyloxyethoxy) phenyl] fluorene, alkylene oxide modified bisphenol A di (meth) acrylate (for example, ethoxylated (ethylene oxide modified) bisphenol A di (meth) acrylate), trimethylolpropane tri (meth) acrylate, tri Methylolethane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythr Polyol polyacrylates such as tall tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, diacrylate of bisphenol A diglycidyl ether, diacrylate of hexanediol diglycidyl ether, etc. Examples thereof include epoxy acrylates, urethane acrylates obtained by reacting polyisocyanate with hydroxyl group-containing acrylates such as hydroxyethyl acrylate, and the like.

(2) Cationic Polymerizable Compound The cationically polymerizable compound is a compound having a cationically polymerizable group. The cationically polymerizable group contained in the cationically polymerizable compound is not particularly limited as long as it is a functional group capable of causing a cationic polymerization reaction, and examples thereof include an epoxy group, an oxetanyl group and a vinyl ether group. When the cationically polymerizable compound has two or more cationically polymerizable groups, these cationically polymerizable groups may be the same or different.

The number of cationically polymerizable groups contained in one molecule of the cationically polymerizable compound is preferably 2 or more, and more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer.
In addition, as the cationically polymerizable compound, among others, a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferable. A cyclic ether group such as an epoxy group or an oxetanyl group is preferable from the viewpoint that the shrinkage accompanying the polymerization reaction is small. Further, among the cyclic ether groups, compounds having an epoxy group are easily available as compounds having various structures, do not adversely affect the durability of the obtained hard coat layer, and easily control the compatibility with the radically polymerizable compound. There is an advantage that. Further, among the cyclic ether groups, the oxetanyl group has a higher degree of polymerization than the epoxy group and has low toxicity. It has the advantages of accelerating the rate of network formation obtained from the polymerizable compound and forming an independent network without leaving unreacted monomer in the film even in the region mixed with the radical polymerizable compound.

  As the cationically polymerizable compound having an epoxy group, for example, polyglycidyl ether of a polyhydric alcohol having an alicyclic ring, or cyclohexene ring, a cyclopentene ring-containing compound, hydrogen peroxide, with a suitable oxidizing agent such as peracid Alicyclic epoxy resin obtained by epoxidation; polyglycidyl ether of aliphatic polyhydric alcohol or alkylene oxide adduct thereof, polyglycidyl ester of aliphatic long-chain polybasic acid, homopolymer of glycidyl (meth) acrylate, Aliphatic epoxy resins such as copolymers; glycidyl ether produced by reacting bisphenol A, bisphenol F, bisphenols such as hydrogenated bisphenol A, or derivatives thereof such as alkylene oxide adducts and caprolactone adducts with epichlorohydrin Ether, and novolac epoxy resins such as a and glycidyl ether type epoxy resins derived from bisphenols are exemplified.

  Examples of the alicyclic epoxy resin include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (UVR-6105, UVR-6107, UVR-6110), bis-3,4-epoxycyclohexylmethyl adipate. (UVR-6128) (These parentheses are trade names and are manufactured by Dow Chemical.).

  Examples of the glycidyl ether type epoxy resin include sorbitol polyglycidyl ether (Denacol EX-611, Denacol EX-612, Denacol EX-614, Denacol EX-614B, Denacol EX-622), polyglycerol polyglycidyl ether (Denacol EX). -512, Denacol EX-521), pentaerythritol polyglycidyl ether (Denacol EX-411), diglycerol polyglycidyl ether (Denacol EX-421), glycerol polyglycidyl ether (Denacol EX-313, Denacol EX-314), Trimethylolpropane polyglycidyl ether (Denacol EX-321), resortinol diglycidyl ether (Denacol EX-201), neopentyl Recall diglycidyl ether (Denacol EX-211), 1,6 hexanediol diglycidyl ether (Denacol EX-212), hydrodibisphenol A diglycidyl ether (Denacol EX-252), ethylene glycol diglycidyl ether (Denacol EX-810). , Denacol EX-811), polyethylene glycol diglycidyl ether (Denacol EX-850, Denacol EX-851, Denacol EX-821), propylene glycol glycidyl ether (Denacol EX-911), polypropylene glycol glycidyl ether (Denacol EX-941, Denacol EX-920), allyl glycidyl ether (Denacol EX-111), 2-ethylhexyl glycidyl ether (Denacor EX-121), phenyl glycidyl ether (Denacol EX-141), phenol glycidyl ether (Denacol EX-145), butylphenyl glycidyl ether (Denacol EX-146), diglycidyl phthalate (Denacol EX-721), hydroquinone diglycidyl ether. (Denacol EX-203), diglycidyl terephthalate (Denacol EX-711), glycidyl phthalimide (Denacol EX-731), dibromophenyl glycidyl ether (Denacol EX-147), dibromoneopentyl glycol diglycidyl ether (Denacol EX-221). (These are the product names in parentheses and made by Nagase Chemtex.).

  Further, as other commercially available epoxy resins, trade names Epicoat 825, Epicoat 827, Epicoat 828, Epicoat 828EL, Epicoat 828XA, Epicoat 834, Epicoat 801, Epicoat 801P, Epicoat 802, Epicoat 815, Epicoat 815XA, Epicoat 816A, Epicoat 819, Epicoat 834X90, Epicoat 1001B80, Epicoat 1001X70, Epicoat 1001X75, Epicoat 1001T75, Epicoat 806, Epicoat 806P, Epicoat 807, Epicoat 152, Epicoat 154, Epicoat 871, Epicoat 191P, Epicoat YX8034, Epicoat DX255, Epicoat YX8034. Etc. (above product name, J Bread epoxy resin) and the like.

  Examples of the cationically polymerizable compound having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane (OXT-101) and 1,4-bis-3-ethyloxetane-3-ylmethoxymethylbenzene (OXT-121). , Bis-1-ethyl-3-oxetanylmethyl ether (OXT-221), 3-ethyl-3-2-ethylhexyloxymethyloxetane (OXT-212), 3-ethyl-3-phenoxymethyloxetane (OXT- 211) (above, product names in parentheses are manufactured by Toagosei), and trade names Etanacol EHO, Etanacor OXBP, Etanacor OXTP, Etanacor OXMA (above product names, Ube Industries).

(3) Polymerization Initiator The at least one polymer of the radically polymerizable compound and the cationically polymerizable compound contained in the hard coat layer used in the present disclosure is, for example, one of the radically polymerizable compound and the cationically polymerizable compound. It can be obtained by adding a polymerization initiator to at least one kind, if necessary, and carrying out a polymerization reaction by a known method.

  As the polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, etc. can be appropriately selected and used. These polymerization initiators are decomposed by at least one of irradiation with light and heating to generate radicals or cations to promote radical polymerization and cation polymerization.

  The radical polymerization initiator may be any one that can release a substance that initiates radical polymerization by at least one of light irradiation and heating. Examples of the photoradical polymerization initiator include imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, and thioxanthone derivatives. More specifically, 1,3-di (tert-butyldioxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetrakis (tert-butyldioxycarbonyl) benzophenone, 3-phenyl-5- Isoxazolone, 2-mercaptobenzimidazole, bis (2,4,5-triphenyl) imidazole, 2,2-dimethoxy-1,2-diphenylethan-1-one (trade name Irgacure 651, Ciba Japan Co., Ltd.) Manufactured), 1-hydroxy-cyclohexyl-phenyl Ketone (product name Irgacure 184, manufactured by Ciba Japan Co., Ltd.), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one (product name Irgacure 369, Ciba Japan ( Co., Ltd.), bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium) (trade name Irgacure 784) , Ciba Japan Co., Ltd., etc., but are not limited thereto.

  In addition to the above, commercially available products can be used, specifically, Ciba Japan Co., Ltd.'s Irgacure 907, Irgacure 379, Irgacure 819, Irgacure 127, Irgacure 500, Irgacure 754, Irgacure 250, Irgacure 1800, Irgacure 1870. , IRGACURE OXE01, DAROCUR TPO, DAROCUR1173, Speedcure MBB, Speedcure PBZ, Speedcure ITX, Speedcure CTX, Speedcure ETX, Speedcure of less than or equal to 0.0, and Speedcure EDB, Ecure of 4 or less than Ecure. Esacure KIP150, Esacure KTO46, KAYACURE birefringence manufactured by Nippon Kayaku Co., Ltd. is 0. 04 or less, and the total light transmittance is 90% or more DETX-S, KAYACURE birefringence is 0.04 or less, and the total light transmittance is 90% or more CTX, KAYACURE BMS, KAYACURE DMBI and the like. Can be mentioned.

Further, the cationic polymerization initiator may be any substance that can release a substance that initiates cationic polymerization by at least one of light irradiation and heating. Examples of the cationic polymerization initiator include sulfonic acid ester, imidosulfonate, dialkyl-4-hydroxysulfonium salt, arylsulfonic acid-p-nitrobenzyl ester, silanol-aluminum complex, (η ⁶ -benzene) (η ⁵ -cyclopentadiene). Examples thereof include enyl) iron (II), and more specific examples thereof include benzoin tosylate, 2,5-dinitrobenzyl tosylate, and N-tocyphthalic acid imide, but are not limited thereto.

  As the radical polymerization initiator, examples of those also used as the cationic polymerization initiator include aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, aromatic phosphonium salts, triazine compounds, iron arene complexes, and the like. More specifically, diphenyliodonium, ditolyliodonium, bis (p-tert-butylphenyl) iodonium, bis (p-chlorophenyl) iodonium and other iodonium chlorides, bromides, borofluoride salts, hexafluorophosphate salts, hexafluoro Iodonium salts such as antimonate salts, triphenylsulfonium, 4-tert-butyltriphenylsulfonium, chlorides of sulfonium such as tris (4-methylphenyl) sulfonium, bromide, borofluoride, hexaf Sulfonium salts such as orophosphate salts and hexafluoroantimonate salts, 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2-phenyl-4,6-bis (trichloromethyl) -1, 2,4,6-substituted-1,3,5 triazine compounds such as 3,5-triazine, 2-methyl-4,6-bis (trichloromethyl) -1,3,5-triazine and the like can be mentioned. It is not limited to these.

(4) Additive The hard coat layer used in the present disclosure includes, in addition to the polymer, an antistatic agent, an antiglare agent, an antifouling agent, and inorganic or organic fine particles for improving hardness, if necessary. It may contain additives such as a leveling agent and various sensitizers.

  At least one polymer of the radically polymerizable compound and the cationically polymerizable compound contained in the hard coat layer used in the present disclosure is a Fourier transform infrared spectrophotometer (FTIR), a pyrolysis gas chromatograph (GC). -MS) and decomposed products of the polymer can be analyzed using a combination of high performance liquid chromatography, gas chromatograph mass spectrometer, NMR, elemental analysis, XPS / ESCA and TOF-SIMS.

3. Laminate Structure The laminate of the present disclosure is not particularly limited as long as it has the polyimide film and the hard coat layer, and the hard coat layer is laminated on one surface side of the polyimide film. The hard coat layer may be laminated on both surfaces of the polyimide film. Further, the laminate of the present disclosure, within a range that does not impair the effects of the present disclosure, in addition to the polyimide film and the hard coat layer, for example, for improving the adhesion between the polyimide film and the hard coat layer. It may have another layer such as a primer layer, or may be one in which the polyimide film and the hard coat layer are laminated via another layer such as a primer layer. Further, the laminate of the present disclosure may be one in which the polyimide film and the hard coat layer are adjacent to each other.

The total thickness of the laminate of the present disclosure may be appropriately selected depending on the application, but from the viewpoint of strength, it is preferably 10 μm or more, and more preferably 40 μm or more. On the other hand, from the viewpoint of bending resistance, it is preferably 300 μm or less, and more preferably 250 μm or less.
In the laminate of the present disclosure, the thickness of each hard coat layer may be appropriately selected depending on the application, but it is preferably 2 μm or more and 80 μm or less, and more preferably 3 μm or more and 50 μm or less. Further, from the viewpoint of curling prevention, hard coat layers may be formed on both sides of the polyimide film.

4. Characteristics of Laminated Body The laminated body of the present disclosure has a pencil hardness of the surface on the side of the hard coat layer of preferably H or higher, more preferably 2H or higher, even more preferably 3H or higher.
The pencil hardness of the laminate of the present disclosure can be measured in the same manner as in the method for measuring the pencil hardness of the polyimide film, except that the load is set to 9.8N.

The laminated body of the present disclosure has a total light transmittance of 85% or more, preferably 88% or more, and more preferably 90% or more, measured according to JIS K7361-1. Is preferred. Since the transmittance is high as described above, the transparency is improved and it can be used as a glass substitute material.
The total light transmittance of the laminate of the present disclosure can be measured in the same manner as the total light transmittance of the polyimide film measured according to JIS K7361-1.

The layered product of the present disclosure has a yellowness index (YI value) calculated according to JIS K7373-2006 of preferably 20 or less, more preferably 12 or less, and even more preferably 10 or less. More preferably, it is particularly preferably 5 or less.
The yellowness (YI value) of the laminate of the present disclosure can be measured in the same manner as the yellowness (YI value) of the polyimide film calculated according to JIS K7373-2006.

The haze value of the laminate of the present disclosure is preferably 10 or less, more preferably 8 or less, and further preferably 5 or less from the viewpoint of light transmittance.
The haze value of the laminate of the present disclosure can be measured in the same manner as the haze value of the polyimide film.

The birefringence index in the film thickness direction of the laminate of the present disclosure at a wavelength of 590 nm is preferably 0.020 or less, more preferably 0.015 or less, and further preferably 0.010 or less, and more preferably Further, it is preferably less than 0.008.
The birefringence of the laminate of the present disclosure can be measured in the same manner as the birefringence of the polyimide film in the film thickness direction at a wavelength of 590 nm.

5. Use of Laminate The use of the laminate of the present disclosure is not particularly limited, and for example, the same use as the use of the above-described polyimide film of the present disclosure can be used.

6. Manufacturing method of laminated body As a manufacturing method of a laminated body of the present disclosure, for example,
At least one surface of the polyimide film of the invention, a step of forming a coating film of a composition for forming a hard coat layer containing at least one of a radically polymerizable compound and a cationically polymerizable compound,
And a step of curing the coating film.

The composition for forming a hard coat layer contains at least one of a radically polymerizable compound and a cationically polymerizable compound, and may further contain a polymerization initiator, a solvent, an additive and the like, if necessary.
Here, as the radically polymerizable compound, the cationically polymerizable compound, the polymerization initiator and the additive contained in the composition for forming a hard coat layer, the same ones as described in the hard coat layer can be used. The solvent can be appropriately selected and used from known solvents.

As a method of forming a coating film of the composition for forming a hard coat layer on at least one surface of a polyimide film, for example, the composition for forming a hard coat layer on at least one surface of a polyimide film is known. A method of applying by means of application means can be mentioned.
The coating means is not particularly limited as long as it is a method capable of coating with a desired film thickness, and examples thereof include the same means as the means for coating the support with the polyimide precursor resin composition.

  The solvent is removed by drying the coating film of the curable resin composition for the hard coat layer, if necessary. Examples of the drying method include reduced pressure drying or heat drying, and a method of combining these dryings. When drying at atmospheric pressure, it is preferable to dry at 30 ° C or higher and 110 ° C or lower.

  The hard coat layer for the curable resin composition is applied, to the coating film dried as necessary, depending on the radically polymerizable compound and the polymerizable group of the cationically polymerizable compound contained in the curable resin composition. By curing the coating film by at least one of light irradiation and heating, a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound on at least one surface of the polyimide film. Can be formed.

Ultraviolet rays, visible light, electron beams, ionizing radiation and the like are mainly used for light irradiation. In the case of ultraviolet curing, ultraviolet rays emitted from light rays such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc and a metal halide lamp are used. The irradiation amount of the energy ray source is about 50 to 5000 mJ / cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm.
When heating, it is usually carried out at a temperature of 40 ° C. or higher and 120 ° C. or lower. The reaction may be carried out by leaving it at room temperature (25 ° C.) for 24 hours or more.

III. Display Surface Material The display surface material of the present disclosure is the above-described polyimide film of the present disclosure or the laminate of the present disclosure.

  The surface material for a display of the present disclosure is arranged and used so as to be located on the surface of various displays. The surface material for a display of the present disclosure, like the above-described polyimide film of the present disclosure and the laminate of the present disclosure, is excellent in transparency and has a reduced phase difference, and is particularly preferably used for a large display. You can

  The surface material for a display of the present disclosure can be used for various known displays and is not particularly limited, and for example, can be used for the display described in the application of the polyimide film of the present disclosure.

  When the surface material for a display of the present disclosure is the laminate of the present disclosure, the surface that is the outermost surface after being placed on the surface of the display may be the surface on the polyimide film side, or the hard coat layer. It may be the side surface. Above all, it is preferable to dispose the surface material for a display of the present disclosure so that the surface on the hard coat layer side becomes the surface on the more front side. The display surface material of the present disclosure may have a fingerprint adhesion preventing layer on the outermost surface.

  The method for disposing the surface material for a display of the present disclosure on the surface of the display is not particularly limited, and examples thereof include a method of interposing an adhesive layer. As the adhesive layer, a conventionally known adhesive layer that can be used for adhering a surface material for a display can be used.

IV. Touch panel member The touch panel member of the present disclosure, the polyimide film of the present disclosure described above or the laminate of the present disclosure described above,
Arranged on one surface side of the polyimide film or the laminate, a transparent electrode composed of a plurality of conductive portions,
A plurality of lead lines electrically connected to at least one side of an end of the conductive portion.

Since the touch panel member of the present disclosure includes the above-described polyimide film or laminate of the present disclosure, it has excellent optical characteristics because it has reduced optical distortion.
The laminate of the present disclosure used for the touch panel member of the present disclosure has a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound, which is adjacent to both surfaces of a polyimide film. Preferably there is.
The touch panel member of the present disclosure is not particularly limited, but it is preferable that the transparent electrode is laminated in contact with one surface side of the laminated body.
The touch panel member of the present disclosure can be arranged and used so as to be located on the surface of various displays, for example. Further, the touch panel member of the present disclosure and the polyimide film or laminate of the present disclosure as a surface material may be arranged and used in this order on the surface of various displays.

Hereinafter, the touch panel member of the present disclosure will be described by way of an example using the above-described laminate of the present disclosure, but instead of the above-described laminate of the present disclosure, the above-described polyimide film of the present disclosure can be similarly used. .
2 is a schematic plan view of one surface of an example of the touch panel member of the present disclosure, FIG. 3 is a schematic plan view of the other surface of the touch panel member shown in FIG. 2, and FIG. FIG. 4 is a cross-sectional view taken along the line AA ′ of the touch panel member shown in FIG. The touch panel member 20 shown in FIGS. 2, 3 and 4 includes a laminated body 10 of the present disclosure, a first transparent electrode 4 arranged in contact with one surface of the laminated body 10, and the other side of the laminated body 10. And a second transparent electrode 5 arranged in contact with the surface. In the first transparent electrode 4, a plurality of first conductive portions 41, which are strip-shaped electrode pieces extending so as to extend in the x-axis direction, are arranged at predetermined intervals. A first lead wire 7 electrically connected to the first conductive portion 41 is connected to the first conductive portion 41 at either one of the ends in the longitudinal direction. A first terminal 71 for electrically connecting to an external circuit may be provided at the end of the first lead wire 7 extending to the edge 21 of the laminated body 10. The first conductive portion 41 and the first lead-out line 7 are generally connected in the inactive area 23, which is located outside the active area 22 visible to the user of the touch panel.
For the connection between the first conductive portion 41 and the first lead wire 7, for example, as shown in FIG. 2, a connection structure in which a connection portion 24 is interposed can be adopted. Specifically, the connection portion 24 can be formed by extending a layer of a conductive material from the longitudinal end portion of the first conductive portion 41 to a predetermined position in the inactive area 23. Furthermore, a connection structure between the first conductive portion 41 and the first lead-out wire 7 can be formed by overlapping at least a part of the first lead-out wire 7 on the connection portion 24.
The connection between the first conductive portion 41 and the first lead wire 7 is not limited to the structure for forming the connection portion 24 as shown in FIG. For example, although not shown, the longitudinal end portion of the first conductive portion 41 is extended to the inactive area 23, and in the inactive area 23, the first conductive portion 41 is extended to the inactive area 23. The two may be electrically connected by riding the first lead-out wire 7 on the end portion of.
Note that, in FIG. 2, a configuration is shown in which one of the longitudinal end portions of the first conductive portion 41 and the first lead-out wire 7 are connected, but in the present disclosure, one first conductive portion is provided. The first lead wire 7 may be electrically connected to both ends of the portion 41 in the longitudinal direction.

As shown in FIG. 3, the touch panel member 20 includes the second transparent electrode 5 arranged in contact with the other surface of the laminated body 10. In the second transparent electrode 5, second conductive portions 51, which are a plurality of strip-shaped electrode pieces extending so as to extend in the y-axis direction, are arranged at a predetermined interval in the x-axis direction. There is.
The second conductive portion 51 is connected to the second lead wire 8 electrically connected to the second conductive portion 51 at one of the longitudinal end portions thereof.
The second lead-out line 8 is extended to a position in the edge 21 of the laminated body 10 where the above-mentioned first lead-out line 7 is extended and does not overlap the first terminal 71. ..
A second terminal 81 for electrically connecting to an external circuit may be provided at the end of the second lead wire 8 that extends to the end edge 21 of the laminated body 10.
The electrical connection between the second conductive portion 51 and the second lead wire 8 may be the same as the electrical connection between the first lead wire 7 and the first conductive portion 41. ..

  The pattern in which the first take-out line 7 is a long wiring and the second take-out line 8 is a short wiring as shown in FIGS. 2 and 3 is merely one embodiment of the touch panel member of the present disclosure. It is also possible to form a pattern in which the first extraction line 7 is a short wiring and the second extraction line 8 is a long wiring. Further, the extending direction of the first take-out line 7 and the extending direction of the second take-out line 8 are not limited to the directions shown in FIGS. 2 and 3, and can be designed arbitrarily.

The conductive portion included in the touch panel member of the present disclosure can be appropriately selected and applied to those that form the transparent electrode in the touch panel member, and the pattern of the conductive portion is not limited to those shown in FIGS. 2 and 3. For example, it is possible to appropriately select and apply a pattern of a transparent electrode capable of detecting a change in electric capacitance due to contact with a finger or the like or a state close to contact by a capacitance method.
The material of the conductive portion is preferably a light-transmissive material, and for example, an indium oxide-based transparent electrode material containing indium tin oxide (ITO), indium oxide, indium zinc oxide (IZO) or the like as a main component. Examples thereof include, but are not limited to, a transparent conductive film containing tin oxide (SnO ₂ ), zinc oxide (ZnO) and the like as a main component, and a conductive polymer compound such as polyaniline and polyacetylene. Further, the first conductive portion 41 and the second conductive portion 51 may be formed by using the same kind of conductive material or different kinds of materials. In particular, it is preferable to form the first conductive portion 41 and the second conductive portion 51 using the same type of conductive material from the viewpoint that the occurrence of warpage or distortion of the touch panel member can be suppressed more effectively.
The thickness of the conductive portion is not particularly limited, but when the conductive portion is formed by, for example, a photolithography method, it can be generally formed to have a thickness of about 10 nm to 500 nm.

The conductive material forming the extraction line included in the touch panel member of the present disclosure may be light transmissive or not. Generally, the extraction line can be formed using a metal material having high conductivity such as silver or copper. Specifically, a simple metal, a metal composite, a metal / metal compound composite, and a metal alloy can be mentioned. Examples of simple metals include silver, copper, gold, chrome, platinum, and aluminum. Examples of the metal composite include MAM (a three-layer structure of molybdenum, aluminum, and molybdenum). Examples of the composite of metal and metal compound include a laminate of chromium oxide and chromium. As the metal alloy, a silver alloy or a copper alloy is commonly used. As the metal alloy, APC (alloy of silver, palladium and copper) and the like can be exemplified. In addition, a resin component may be appropriately mixed with the above-mentioned metal material in the extraction line.
In the touch panel member of the present disclosure, the terminal provided at the end of the lead wire can be formed using, for example, the same material as the lead wire.
The thickness and the width dimension of the extraction line are not particularly limited, but when the extraction line is formed by, for example, a photolithography method, the thickness is generally formed to about 10 nm to 1000 nm, and the width dimension is 5 μm to The thickness is about 200 μm. On the other hand, when the extraction line is formed by printing such as screen printing, generally, the thickness is formed to about 5 μm to 20 μm and the width dimension is formed to about 20 μm to 300 μm.

The touch panel member of the present disclosure is not limited to the form shown in FIGS. 2 to 4, and is configured by, for example, stacking a first transparent electrode and a second transparent electrode on separate laminates. It may be one.
5 and 6 are schematic plan views each showing an example of a conductive member including the laminate of the present disclosure. The first conductive member 201 shown in FIG. 5 includes the laminated body 10 of the present disclosure and the first transparent electrode 4 arranged in contact with one surface of the laminated body 10, and The transparent electrode 4 has a plurality of first conductive parts 41. The second conductive member 202 illustrated in FIG. 6 includes the laminated body 10 ′ of the present disclosure and the second transparent electrode 5 arranged in contact with one surface of the laminated body 10 ′. The second transparent electrode 5 has a plurality of second conductive parts 51.
FIG. 7 is a schematic cross-sectional view showing another example of the touch panel member of the present disclosure, and the touch panel member 20 ′ shown in FIG. 7 is a first conductive member 201 shown in FIG. 5 and a second conductive member 201 shown in FIG. And a conductive member 202. In the touch panel member 20 ′, the surface of the first conductive member 201 not having the first transparent electrode 4 and the surface of the second conductive member 202 having the transparent electrode 5 are separated by the adhesive layer 6. It is stuck together. In the present disclosure, for example, an adhesive layer for adhering the laminate of the present disclosure and the touch panel member of the present disclosure, an adhesive layer for adhering the touch panel members of the present disclosure, a touch panel member of the present disclosure, and a display device. As the adhesive layer for adhering to the above, a conventionally known adhesive layer used for an optical member can be appropriately selected and used. In the conductive member used for the touch panel member of the present disclosure, the configurations and materials of the transparent electrode, the lead wire, and the terminal may be the same as those of the transparent electrode, the lead wire, and the terminal used for the touch panel member of the present disclosure described above. it can.

V. Liquid crystal display device The liquid crystal display device of the present disclosure, the polyimide film of the present disclosure described above or the laminate of the present disclosure described above, the liquid crystal between the opposing substrates arranged on one surface side of the polyimide film or the laminate. A liquid crystal display portion having a layer.

Since the liquid crystal display device of the present disclosure includes the above-described polyimide film of the present disclosure or the above-described laminated body of the present disclosure, the optical distortion is reduced, and thus the optical characteristics are excellent.
The laminated body of the present disclosure used for the liquid crystal display device of the present disclosure has a hard coat layer adjacent to both surfaces of a polyimide film and containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound. Is preferred.
Further, the liquid crystal display device of the present disclosure may include the touch panel member of the present disclosure described above.
The counter substrate included in the liquid crystal display device of the present disclosure may include the polyimide film or the laminate of the present disclosure.

Hereinafter, the liquid crystal display device of the present disclosure will be described by way of an example using the above-described laminated body of the present disclosure, but instead of the above-described laminated body of the present disclosure, the above-described polyimide film of the present disclosure may be similarly used. it can.
FIG. 8 is a schematic cross-sectional view showing an example of the liquid crystal display device of the present disclosure. A liquid crystal display device 100 illustrated in FIG. 8 includes a laminated body 10 of the present disclosure and a first transparent electrode 4 on one surface of a laminated body 10 ′ of the present disclosure, and a second transparent electrode 5 on the other surface. The touch panel member 20 including the liquid crystal display unit 30 and the liquid crystal display unit 30. In the liquid crystal display device 100, the laminated body 10 is used as a surface material, and the laminated body 10 and the touch panel member 20 are bonded together via the adhesive layer 6.

The liquid crystal display unit used in the liquid crystal display device of the present disclosure has a liquid crystal layer formed between the substrates arranged to face each other, and a configuration used in a conventionally known liquid crystal display device can be adopted. it can.
The driving method of the liquid crystal display device of the present disclosure is not particularly limited, and a driving method generally used for liquid crystal display devices can be adopted. For example, a TN method, an IPS method, an OCB method, and an MVA method. Etc. can be mentioned.
The counter substrate used in the liquid crystal display device of the present disclosure can be appropriately selected and used according to the driving method of the liquid crystal display device, and the one including the polyimide film or the laminate of the present disclosure may be used.
As the liquid crystal forming the liquid crystal layer, various liquid crystals having different dielectric anisotropy and a mixture thereof can be used depending on the driving method of the liquid crystal display device of the present disclosure.
As a method for forming the liquid crystal layer, a method generally used as a method for producing a liquid crystal cell can be used, and examples thereof include a vacuum injection method and a liquid crystal dropping method. After forming the liquid crystal layer by the above method, the enclosed liquid crystal can be oriented by gradually cooling the liquid crystal cell to room temperature.
In the liquid crystal display device of the present disclosure, a colored layer of a plurality of colors and a light-shielding portion that defines pixels may be further provided between the substrates that are arranged to face each other. Further, the liquid crystal display unit may have a backlight unit having a light emitting element and a phosphor at a position opposite to the side where the touch panel member is located, on the outer side of the substrates arranged to face each other. Further, a polarizing plate may be provided on each of the outer surfaces of the substrates arranged to face each other.

  FIG. 9 is a schematic cross-sectional view showing another example of the liquid crystal display device of the present disclosure. A liquid crystal display device 200 shown in FIG. 9 includes a laminated body 10 of the present disclosure, a first conductive member 201 including a first transparent electrode 4 on one surface of a laminated body 10 ′ of the present disclosure, and a first conductive member 201 of the present disclosure. The liquid crystal display device 30 includes a touch panel member 20 ′ having a second conductive member 202 provided with the second transparent electrode 5 on one surface of the laminate 10 ″, and a liquid crystal display unit 30. The first conductive member 201, and the first conductive member 201 and the second conductive member 202 are attached to each other via the adhesive layer 6. The configuration of the touch panel member 20 'is, for example, The configuration may be similar to that of the touch panel member 20 ′ shown in Fig. 7. As the conductive member used in the liquid crystal display device of the present disclosure, the same conductive member used in the touch panel member of the present disclosure may be used. Can be used Kill.

VI. Organic electroluminescence display device The organic electroluminescence display device of the present disclosure, the polyimide film of the present disclosure described above or the laminate of the present disclosure described above, is disposed on one surface side of the polyimide film or the laminate, facing. And an organic electroluminescence display section having an organic electroluminescence layer between substrates.

Since the organic electroluminescence display device of the present disclosure includes the above-described polyimide film of the present disclosure or the above-described laminate of the present disclosure, the optical distortion is reduced, and thus the optical characteristics are excellent.
The laminate of the present disclosure used in the organic electroluminescence display device of the present disclosure has a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound adjacent to both surfaces of a polyimide film. It is preferable to have one.
The organic electroluminescence display device of the present disclosure may include the touch panel member of the present disclosure described above.
In addition, the counter substrate included in the organic electroluminescence display device of the present disclosure may include the polyimide film or the laminate of the present disclosure.

  FIG. 10 is a schematic cross-sectional view showing an example of the organic electroluminescence display device of the present disclosure. An organic electroluminescence display device 300 shown in FIG. 10 includes a laminated body 10 of the present disclosure and a first transparent electrode 4 on one surface of a laminated body 10 ′ of the present disclosure, and a second transparent electrode on the other surface. It has the touch panel member 20 provided with the electrode 5, and the organic electroluminescent display part 40. In the organic electroluminescence display device 300, the laminated body 10 is used as a surface material, and the laminated body 10 and the touch panel member 20 are bonded together via the adhesive layer 6.

The organic electroluminescence display unit (organic EL display unit) used in the organic electroluminescence display device (organic EL display device) of the present disclosure has an organic electroluminescence layer (organic EL layer) formed between substrates arranged facing each other. It is possible to employ a configuration used in a conventionally known organic EL display device.
The organic EL display unit further includes a supporting substrate, an organic EL element including an organic EL layer and an anode layer and a cathode layer that sandwich the organic EL layer, and a sealing base material that seals the organic EL element. May be. The organic EL layer may have at least an organic EL light emitting layer, and for example, from the anode layer side, a hole injection layer, a hole transport layer, an organic EL light emitting layer, an electron transport layer and an electron injection layer. A layer having a layered structure in this order can be used.
The organic EL display device of the present disclosure can be applied to, for example, a passive drive type organic EL display and an active drive type organic EL display. The counter substrate used in the organic EL display device of the present disclosure can be appropriately selected and used according to the driving method of the organic EL display device, and the one including the laminate of the present disclosure may be used.

  FIG. 11 is a schematic cross-sectional view showing another example of the organic electroluminescence display device of the present disclosure. An organic electroluminescence display device 400 shown in FIG. 11 includes a laminated body 10 of the present disclosure, a first conductive member 201 including a first transparent electrode 4 on one surface of a laminated body 10 ′ of the present disclosure, and a book. The disclosed laminated body 10 ″ includes a touch panel member 20 ′ having a second conductive member 202 provided with the second transparent electrode 5 on one surface, and an organic electroluminescent display unit 40. Organic electroluminescent display device In 400, the laminated body 10 and the 1st electroconductive member 201 and the 1st electroconductive member 201 and the 2nd electroconductive member 202 are bonded together via the adhesive layer 6. Touch panel member 20 '. The configuration can be similar to, for example, the configuration of the touch panel member 20 ′ shown in Fig. 7. Used in the organic electroluminescence display device of the present disclosure. As the conductive member, it can be the same as the conductive member for use in a touch panel member of the present disclosure.

  Hereinafter, unless otherwise specified, measurement or evaluation was performed at 25 ° C.

[Evaluation methods]
<Weight average molecular weight of polyimide precursor>
The weight average molecular weight of the polyimide precursor is 0.5% by weight of the polyimide precursor in N-methylpyrrolidone (NMP) solution, the solution is filtered through a syringe filter (pore diameter: 0.45 μm), and developed. As the solvent, a 10 mmol% LiBr-NMP solution having a water content of 500 ppm or less was used, and a GPC device (manufactured by Tosoh Corporation, HLC-8120, column used: GPC LF-804 manufactured by SHODEX) was used, and a sample injection amount of 50 μL, a solvent flow rate of 0.5 mL. The measurement was performed under the conditions of 40 ° C./min. The weight average molecular weight of the polyimide precursor is the polystyrene standard sample of the same concentration as the sample (weight average molecular weight: 364,700, 204,000, 103,500, 44,360,27,500,13,030,6,300, 3,070) as a converted value with respect to standard polystyrene measured. The elution time was compared with the calibration curve to determine the weight average molecular weight.
<Viscosity of polyimide precursor solution>
The viscosity of the polyimide precursor solution was measured with a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.) at 25 ° C. as a sample amount of 0.8 mL.

<Film thickness measuring method>
The film thickness of 5 points in total at the four corners and the center of the polyimide film test piece cut into a size of 10 cm × 10 cm was measured using a digital linear gauge (manufactured by Ozaki Seisakusho, model PDN12 digital gauge), and the measured value was obtained. Was used as the film thickness of the polyimide film.

<Tan δ curve>
A dynamic viscoelasticity measuring device RSA-G2 (manufactured by TA Instruments) was used in a measuring room of 23 ° C. and 56% RH to set the measuring range to −40 ° C. or higher and 500 ° C. or lower, and tensile was selected as a deformation mode, and a nitrogen atmosphere was selected. Under a frequency of 1 Hz, a temperature rising rate of 10 ° C./min, a minimum load of 2 g, Axial force> Dynamic Force 1.5%, and Strain 0.1%. Further, a test piece having a length of 40 mm and a width of 5 mm was prepared, and dynamic viscoelasticity measurement was performed with a chuck distance of 20 mm, and tan δ (tan δ = loss elastic modulus (E ″) / storage elastic modulus (E ′)). Was obtained. At the time of analysis of peaks and inflection points, data was digitized and analyzed from the numerical values without visual evaluation.
<RSA-G2 measurement conditions>
(Initial value)
Axial force: 3.0 g
Sensitivity: 1.0 g
Proportional force Mode: Force Tracking
Axial Force> Dynamic Force: 1.5%
Minimum axial force: 2.0 g
Programmed Extension Bellow: 0 Pa
(Auto strain)
Mode: Enabled
Strain adjust: 20.0%
Minimum strain: 0.01%
Maximum strain: 3.0%
Minimum force: 1.5 g
Maximum force: 200.0 g
(Test parameters)
Sampling rate: 10 pts / s
Strain%: 0.1%
Frequency: Single point
Frequency 1Hz
In addition, as a sample for measuring the tan δ curve, a polyimide film left standing in an environment of 23 ° C. ± 2 ° C. RH30 to 50% for 24 hours was sampled into 10 cm square or more, and the central portion of the film was further cut with a razor or a scalpel. Using a cutting jig having a slit of 5 mm width, a piece cut into a width of 5 mm and a length of 50 mm (so that the sample length was 20 mm when chucked) was used. The width was measured using a caliper, and the average value measured three times at different positions was recorded. At this time, when a part of the width measurement had a fluctuation range of 3% or more of the average value, the sample was not used. As the thickness of the polyimide film, the value measured by the film thickness measuring method was used.

<Total light transmittance>
According to JIS K7361-1, it was measured by a haze meter (HM150 manufactured by Murakami Color Research Laboratory).

<Phase difference, birefringence>
The retardation value (Rth) in the film thickness direction of the polyimide film was measured by using a retardation measuring device (manufactured by Oji Scientific Instruments Co., Ltd., product name “KOBRA-WR”) at 25 ° C. with light having a wavelength of 590 nm. Regarding the retardation value (Rth) in the film thickness direction, the retardation value at 0 degree incidence and the retardation value at 40 degree oblique incidence were measured, and the retardation value Rth in the film thickness direction was calculated from these retardation values. The retardation value at an incident angle of 40 degrees was measured by allowing light having a wavelength of 590 nm to enter the retardation film from a direction inclined by 40 degrees from the normal line of the retardation film.
The birefringence of the polyimide film was determined by substituting the formula: Rth / d (thickness (nm) of the polyimide film).

<YI value (yellowness)>
The YI value was measured by using an ultraviolet-visible near-infrared spectrophotometer (V-7100, JASCO Corporation) in accordance with JIS K7373-2006, by a spectrocolorimetric method, using an auxiliary illuminant C, and a second visual field. , Tristimulus values X, Y, Z in the XYZ color system are obtained based on the transmittance measured in the range of 250 nm or more and 800 nm or less at 1 nm intervals. Calculated.
YI = 100 (1.2769X-1.0592Z) / Y

<Haze value>
It was measured by a haze meter (HM150 manufactured by Murakami Color Research Laboratory) according to JIS K-7105.

(Synthesis example 1)
A solution prepared by dissolving 302.0 g of dehydrated dimethylacetamide and 2.49 g (10 mmol) of 1,3-bis (3-aminopropyl) tetramethyldisiloxane (AprTMOS) in a 500 mL separable flask is a liquid. Where the temperature was controlled to 30 ° C., 2.22 g (5 mmol) of 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) was gradually added so that the temperature rise was 2 ° C. or less. , Stirred with a mechanical stirrer for 4 hours. 2,2'-bis (trifluoromethyl) benzidine (TFMB) (28.8 g, 90 mmol) was added thereto, and after confirming complete dissolution, 4,4 '-(hexafluoroisopropylidene) diphthalic acid 42.0 g (94.5 mmol) of an anhydride (6FDA) was gradually added in several times so that the temperature rise was 2 ° C. or less, and the polyimide precursor solution 1 (solid content 20) in which the polyimide precursor 1 was dissolved was added. Wt%) was synthesized. The molar ratio of TFMB and AprTMOS used in the polyimide precursor 1 was 90:10. The viscosity of the polyimide precursor solution 1 (solid content: 20 mass%) at 25 ° C. was 40150 cps, and the weight average molecular weight of the polyimide precursor 1 measured by GPC was 253,000.

(Synthesis example 2)
Reaction was carried out by the procedure of Synthesis Example 1 so that the molar ratio of TFMB and AprTMOS (TFMB: AprTMOS) was 80:20 to obtain a polyimide precursor solution 2. The viscosity of the polyimide precursor solution 2 (solid content 25 mass%) at 25 ° C. was 10180 cps, and the weight average molecular weight of the polyimide precursor 2 measured by GPC was 109000.

(Synthesis example 3)
Reaction was carried out according to the procedure of Synthesis Example 1 so that the molar ratio of TFMB and AprTMOS (TFMB: AprTMOS) was 60:40 to obtain a polyimide precursor solution 3. The viscosity of the polyimide precursor solution 3 (solid content: 30% by mass) at 25 ° C. was 17,300 cps, and the weight average molecular weight of the polyimide precursor 3 measured by GPC was 86,000.

(Synthesis example 4)
According to the procedure of Synthesis Example 1, the reaction was carried out so that the molar ratio of TFMB and AprTMOS (TFMB: AprTMOS) was 95: 5 to obtain a polyimide precursor solution 4. The viscosity of the polyimide precursor solution 4 (solid content: 25% by mass) at 25 ° C. was 95300 cps, and the weight average molecular weight of the polyimide precursor 4 measured by GPC was 186500.

(Synthesis example 5)
A 500 mL separable flask was charged with 3081 g of dehydrated dimethylacetamide and 322 g (1.00 mol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB), and the solution temperature of the solution containing TFMB was changed. Whereas the temperature was controlled to 30 ° C, 443 g (1.00 mol) of 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) was gradually divided into several times so that the temperature rise was 2 ° C or less. To prepare a polyimide precursor solution 5 (solid content 20% by weight) in which the polyimide precursor 5 was dissolved. The viscosity of the polyimide precursor solution 5 (solid content 20% by weight) at 25 ° C. was 34920 cps, and the weight average molecular weight of the polyimide precursor 5 measured by GPC was 408500.

(Examples 1 to 4, Comparative Example 2)
The polyimide precursor solutions shown in Table 1 were used to perform thermal imidization in accordance with the following procedures (1) to (3) to produce polyimide films of Examples 1 to 4 and Comparative Example 2.
(1) Each polyimide precursor solution was applied onto glass and dried in a circulating oven at 120 ° C for 10 minutes.
(2) Under a nitrogen stream (oxygen concentration of 100 ppm or less), the temperature was raised to 350 ° C. at a temperature rising rate of 10 ° C./min, and the temperature was maintained at 350 ° C. for 1 hour and then cooled to room temperature.
(3) It was peeled from the glass to obtain each polyimide film.

(Example 5)
The polyimide film of Example 5 was produced by using the polyimide precursor solution 4 and performing thermal imidization according to the following procedures (1) to (3).
(1) Polyimide precursor solution 4 was applied on a continuous heat-resistant polyimide film.
(2) Using a hot air type continuous heating furnace, the temperature is raised stepwise from 80 ° C to 180 ° C and dried for a total of about 120 minutes.
(3) Under a nitrogen stream, oxygen concentration (100 to 1,000 ppm) and a continuous heating furnace equipped with a far infrared heater were used to raise the temperature to 330 ° C. at a temperature rising rate of 8 ° C./min and hold at 330 ° C. for 15 minutes. Then, it cooled to room temperature. Then, the polyimide film was peeled off from the continuous base material to obtain the polyimide film of Example 5.

(Comparative Example 1)
Polyimide precursor solution 4 (300.0 g) and dehydrated dimethylacetamide (120.0 g) were added to a 500 mL separable flask and stirred until uniform. After completion of the stirring, 34.9 g (0.22 mol) of pyridine as a catalyst and 45.1 g (0.22 mol) of acetic anhydride were added to the separable flask and stirred at room temperature for 24 hours.
The obtained solution (400.0 g) was transferred to a 5 L separable flask, butyl acetate (272.0 g) was added, and the mixture was stirred until it became uniform. After completion of stirring, methanol (672.0 g) was gradually added to the separable flask to obtain a solution in which slight turbidity was observed. Methanol (2.016 kg) was added to the obtained solution all at once to obtain a white slurry. The obtained slurry was filtered and then washed 5 times with methanol to obtain polyimide 1 (60.5 g). Polyimide 1 was dissolved in DMAc to prepare a polyimide solution 1 having a solid content of 20% by mass.
By using the polyimide solution 1 obtained as described above, the following procedures (1) to (3) were performed to prepare a polyimide film having a thickness of 50 μm.
(1) The polyimide solution 1 was applied on glass, dried in a circulation oven at 40 ° C. for 60 minutes, and then dried in a circulation oven at 100 ° C. for 30 minutes.
(2) Under a nitrogen stream (oxygen concentration of 100 ppm or less), the temperature was raised to 250 ° C. at a temperature rising rate of 10 ° C./min, held at 250 ° C. for 1 hour, and then cooled to room temperature.
(3) The polyimide film of Comparative Example 1 was obtained by peeling from the glass.

  Each polyimide film was evaluated using the above evaluation method. The evaluation results are shown in Table 1. Further, tan δ curve, storage elastic modulus curve and loss elastic modulus curve of the polyimide films of Examples 1 to 5, Comparative Example 1 and Comparative Example 2 are shown in FIGS. 12 to 18, respectively.

The results are shown in Table 1. In addition, as shown in FIGS. 12 to 16, in Examples 1 to 5, the maximum value of tan δ in the temperature region of the temperature of the high temperature side minimum value of the first peak or more and 500 ° C. or less is the maximum value of the second peak. there were.
From Table 1, in the tan δ curve, the polyimide film of Comparative Examples 1 and 2 having the first peak with the maximum maximum value and the maximum value of tan δ in the first peak high temperature side temperature region is less than 0.18, Although the total light transmittance was 90% or more and there was no problem in transparency, the film had a large birefringence of 0.008 or more and a large retardation.
On the other hand, in the tan δ curve, it has the first peak with the maximum maximum value, and the maximum value of tan δ in the first peak high temperature side temperature region is 0.18 or more, which is equivalent to the polyimide film of the present disclosure. Since the polyimide films of Examples 1 to 5 have a total light transmittance of 90% or more and a birefringence of 0.004 or less, it is shown to be a resin film having excellent transparency and a low retardation. Was done.

1 1st peak having the maximum value on the tan δ curve 2 Minimum value of high temperature side of 1st peak 2t Temperature of minimum value of high temperature side of 1st peak 3 Temperature of minimum temperature of high temperature side of 1st peak to 500 ° C Maximum value of tan δ in region 10, 10 ′, 10 ″ Laminate 4 First transparent electrode 41 First conductive portion 5 Second transparent electrode 51 Second conductive portion 6 Adhesive layer 7 First extraction line 71th One terminal 8 Second extraction line 81 Second terminal 20, 20 'Touch panel member 21 Edge of laminate 22 Active area 23 Inactive area 24 Connection portion 201 First conductive member 202 Second conductive member 30 liquid crystal display unit 40 organic electroluminescence display unit 100, 200 liquid crystal display device 300, 400 organic electroluminescence display device

Claims (13)

In the temperature-loss tangent (tan δ) curve obtained by the dynamic viscoelasticity measurement, the maximum value of tan δ in the temperature range from the temperature of the minimum value on the high temperature side of the first peak having the maximum maximum value to 500 ° C. or less is 0.18. Is over,
A polyimide film having a total light transmittance of 85% or more measured according to JIS K7361-1.   The polyimide film according to claim 1, wherein the maximum value of tan δ is 0.18 or more in a temperature range of 300 ° C. or higher and 450 ° C. or lower, which is equal to or higher than the temperature on the high temperature side minimum value of the first peak.   3. The polyimide film according to claim 1, wherein the maximum value of tan δ is 0.18 or more in a temperature range of 350 ° C. or higher and 450 ° C. or lower, which is equal to or higher than the temperature on the high temperature side minimum value of the first peak.   A structure containing an aromatic ring and comprising (i) a fluorine atom, (ii) an aliphatic ring, and (iii) a structure in which aromatic rings are linked to each other by a sulfonyl group or an alkylene group which may be substituted with fluorine. The polyimide film according to claim 1, further comprising a polyimide containing at least one selected from the group. The polyimide film according to any one of claims 1 to 4, which contains a polyimide having a structure represented by the following general formula (1).

(In the general formula (1), R ¹ represents a tetravalent group that is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ² represents a divalent group that is a diamine residue, and A diamine residue having a group ring or an aliphatic ring is contained, and n represents the number of repeating units.) In the polyimide having the structure represented by the general formula (1), R ² in the general formula (1) is a diamine residue having no silicon atom, and one or two silicon atoms in the main chain. Represents a divalent group which is at least one selected from the diamine residues having, and 2.5 mol% or more and 50 mol% or less of the total amount of R ² is a diamine residue having 1 or 2 silicon atoms in the main chain. The polyimide film according to claim 5, wherein 50% by mole or more and 97.5% by mole or less is a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring. In the polyimide having the structure represented by the general formula (1), R ¹ in the general formula (1) is cyclohexanetetracarboxylic acid dianhydride residue, cyclopentanetetracarboxylic acid dianhydride residue, di Cyclohexane-3,4,3 ', 4'-tetracarboxylic dianhydride residue, cyclobutanetetracarboxylic dianhydride residue, pyromellitic dianhydride residue, 3,3', 4,4'- Biphenyltetracarboxylic dianhydride residue, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride residue, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride residue, 3, 4 '-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene) diphthalic anhydride residue, 4,4'-oxydiphthalic anhydride residue, and 3, '- is at least one tetravalent group selected from the group consisting of oxydiphthalic anhydride residue, a polyimide film according to claim 5 or 6. In the polyimide having the structure represented by the general formula (1), the diamine residue having the aromatic ring or the aliphatic ring in R ² in the general formula (1) is a trans-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4′-diaminodiphenylsulfone residue, 3,4′-diaminodiphenylsulfone residue, 2,2-bis (4-aminophenyl) propane residue, 3,3'-bis (trifluoromethyl) -4,4 '-[(1,1,1,3,3,3-hexafluoropropane-2,2-diyl) bis (4,1-phenyleneoxy) ] Dianiline residue, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, 2,2-bis [4- (4 -A Nophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, and at least one 2 selected from the group consisting of divalent groups represented by the following general formula (2). The polyimide film according to any one of claims 5 to 7, which is a valent group.

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.)   A laminate comprising the polyimide film according to any one of claims 1 to 8 and a hard coat layer containing a polymer of at least one of a radically polymerizable compound and a cationically polymerizable compound.   A surface material for a display, which is the polyimide film according to any one of claims 1 to 8 or the laminate according to claim 9. A polyimide film according to any one of claims 1 to 8 or a laminate according to claim 9,
Arranged on one surface side of the polyimide film or the laminate, a transparent electrode composed of a plurality of conductive portions,
A plurality of lead lines electrically connected to at least one side of an end of the conductive portion, a touch panel member. A polyimide film according to any one of claims 1 to 8 or a laminate according to claim 9,
A liquid crystal display device, comprising: a liquid crystal display unit having a liquid crystal layer between opposing substrates, the liquid crystal display unit being disposed on one surface side of the polyimide film or the laminate. A polyimide film according to any one of claims 1 to 8 or a laminate according to claim 9,
An organic electroluminescence display device, comprising: an organic electroluminescence display unit having an organic electroluminescence layer between opposing substrates, the organic electroluminescence display unit being disposed on one surface side of the polyimide film or the laminate.

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