TW202000470A - Method for manufacturing transparent resin film capable of obtaining a homogeneous transparent resin film - Google Patents

Abstract

The invention provides a method for manufacturing a transparent resin film, which is capable of obtaining a homogeneous transparent resin film. The manufacturing method for a transparent resin film in the present invention comprises the following steps: respectively holding two ends of a strip-shaped transparent resin film generated by selecting from a group consisting of a polyimide resin and a polyamide resin; carrying the held film; setting the width of the held film to a specific distance and the resin film is subjected to heat treatment in the dryer. The ratio of the width of the heat-treated film to the width of the film before heat treatment is set to 1.1 or less; and the holding of the resin film is released after leaving the dryer.

Description

Manufacturing method of transparent resin film

The invention relates to a method for manufacturing a transparent resin film.

In flexible display devices, transparent resin films that are replacing glass are being sought. As a material of such a transparent resin film, a material having transparency and mechanical strength such as polyimide-based resin or polyamide-based resin is known.

In the manufacture of such a transparent resin film, a heat treatment of the resin film may be carried out in order to obtain a desired quality (for example, refer to Patent Document 1).

However, if such heat treatment is performed, there may be cases where the uniformity of the obtained transparent resin film cannot be obtained. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-36414

[Problems to be solved by the invention]

The present invention was made in view of such circumstances, and an object thereof is to provide a method for manufacturing a transparent resin film that has good homogeneity even if heat treatment is performed. [Technical means to solve the problem]

That is, the present invention provides the following. [1] A method for manufacturing a transparent resin film, comprising the steps of: forming a long strip containing at least one resin selected from the group consisting of polyimide-based resins and polyamide-based resins The two ends of the transparent resin film are held separately; the film to be held is transported; the width of the film to be held is set to a specific distance and the above resin film is heat-treated in a dryer, and the width of the heat-treated film is relative to The ratio of the width of the film before heat treatment is set to 1.1 or less; and the holding of the resin film leaving the dryer is released. [2] The production method described in [1], wherein the ratio of the width of the film after heat treatment to the width of the film before heat treatment is 0.7 to 1.0. [3] The manufacturing method according to [1] or [2], wherein the holding is performed by a plurality of jigs. [4] The manufacturing method as described in [3], wherein the driving device mounted with the jig is moved at the same speed as the transport speed of the film. [5] The manufacturing method according to [4], wherein the driving device is driven by a chain. [6] The manufacturing method described in any one of [3] to [5], wherein the space between adjacent jigs is 1 to 20 mm. [7] The manufacturing method according to any one of [3] to [6], wherein when the straight line orthogonal to the film conveying axis is aligned with the center of the holding portion of the jig at one end of the film, the straight line and the other of the film The distance between the intersection of one end and the center of the holding part of the jig at the other end of the membrane is 3 mm or less. [8] The production method according to any one of [1] to [7], wherein the content of the organic solvent contained in the resin film after heat treatment is 0.001 to 3% by mass relative to the mass of the resin film. [9] The production method according to any one of [1] to [8], wherein after releasing the holding of the film, there is a step of cutting both ends of the film. [10] The manufacturing method according to [9], wherein after the film is cut, there is a step of bonding a protective film on the resin film. [11] The manufacturing method according to [10], wherein after the protective film is attached, there is a step of cutting the resin film to which the protective film is attached. [12] The manufacturing method according to [10] or [11], wherein after the protective film is attached, there is a step of winding the resin film into a roll. [Effect of invention]

As described above, the present invention provides a method for manufacturing a transparent resin film, which can obtain a homogeneous transparent resin film.

The materials, dimensions, etc. illustrated in the following description are examples, and the present invention is not necessarily limited to these, and can be implemented with appropriate changes within the scope without changing the gist thereof.

The present invention provides a method for manufacturing a transparent resin film, which includes the steps of: forming a long strip containing at least one resin selected from the group consisting of polyimide-based resins and polyamide-based resins The two ends of the transparent resin film are held separately; the film to be held is transported; the width of the film to be held is set to a specific distance and the above resin film is heat-treated in a dryer, and the width of the heat-treated film is relative to The ratio of the width of the film before heat treatment is set to 1.1 or less; and the holding of the resin film leaving the dryer is released.

[Polyimide-based resin, Polyamide-based resin] The transparent resin film of the present invention contains at least one resin selected from the group consisting of polyimide-based resins and polyamide-based resins. The polyimide-based resin system means a polymer selected from the group consisting of a repeating structural unit containing an amide imide group (hereinafter, sometimes referred to as a polyimide), and both containing an amide imide group and an amide group. At least one polymer in the group consisting of polymers of repeating structural units (hereinafter, sometimes described as polyamidoamide). In addition, the polyamido-based resin system means a polymer containing a repeating structural unit containing an amide group.

The polyimide-based resin preferably has a repeating structural unit represented by formula (10). Here, G is a tetravalent organic group, and A is a divalent organic group. The polyimide-based resin may contain two or more types of repeating structural units represented by formula (10) in which G and/or A are different.

The polyimide-based resin may also include one selected from the group consisting of repeating structural units represented by formula (11), formula (12), and formula (13) within the range that does not damage various physical properties of the transparent resin film the above.

In formula (10) and formula (11), G and G ¹ are each independently a tetravalent organic group, preferably an organic group that may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. Examples of G and G ^{1 include} formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), and formula ( 28) The group represented by the formula (29) and a 4-valent chain hydrocarbon group having a carbon number of 6 or less. In terms of easily suppressing the yellowness (YI value) of the transparent resin film, the formulas (20), (21), (22), (23), (24), and (25) are particularly preferred. , Formula (26) or Formula (27).

In formula (20) to formula (29), * represents a bonding bond, and Z represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C( CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH _2- Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-. Ar represents a C 6-20 arylene group which may be substituted by a fluorine atom, and specific examples include phenylene group.

In formula (12), G ² is a trivalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a hydrocarbon group substituted with fluorine. As G ² , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) can be exemplified Or any one of the bonding bonds of the group represented by formula (29) is substituted with a hydrogen atom and a trivalent chain hydrocarbon group with a carbon number of 6 or less.

In formula (13), G ³ is a divalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a hydrocarbon group substituted with fluorine. As G ³ , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) can be exemplified Or, in the bonding bond of the group represented by formula (29), two groups that are not adjacent to each other are substituted with a hydrogen atom and a chain hydrocarbon group having 6 or less carbon atoms.

In formula (10) to formula (13), A, A ¹ , A ² and A ³ are each independently a divalent organic group, preferably an organic group that may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As A, A ¹ , A ² and A ³ , formula (30), formula (31), formula (32), formula (33), formula (34), formula (35), formula (36), formula can be exemplified (37) or the group represented by formula (38); those substituted with methyl, fluoro, chloro, or trifluoromethyl; and chain hydrocarbon groups with a carbon number of 6 or less.

In formula (30) to formula (38), * represents a bonding bond, and Z ¹ , Z ² and Z ³ are each independently, and represent a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -,- CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or -CO-. As an example, Z ¹ and Z ^{3 are} -O- and Z ² is -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, or -SO ₂ -. The bonding positions of Z ¹ and Z ² with respect to each ring, and the bonding positions of Z ² and Z ³ with respect to each ring are preferably meta or para with respect to each ring, respectively.

Regarding the polyimide-based resin, from the viewpoint of easily improving visibility, a polyamidoamide having at least a repeating structural unit represented by formula (10) and a repeating structural unit represented by formula (13) is preferred amine. In addition, the polyamide resin preferably has at least a repeating structural unit represented by formula (13).

In one embodiment of the present invention, the polyimide-based resin is composed of a diamine and a tetracarboxylic acid compound (a related compound of a tetracarboxylic acid compound such as an acetyl chloride compound and a tetracarboxylic dianhydride), and a dicarboxylic acid if necessary Condensed polymer obtained by reaction (polycondensation) of acid compounds (dicarboxylic acid compounds such as acetyl chloride compounds) and tricarboxylic acid compounds (tricarboxylic acid compounds such as acetyl chloride compounds and tricarboxylic anhydrides). The repeating structural unit represented by formula (10) or formula (11) is usually derived from a diamine and a tetracarboxylic acid compound. The repeating structural unit represented by formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

In one embodiment of the present invention, the polyamide resin is a condensation-type polymer obtained by reacting (condensing) a diamine and a dicarboxylic acid compound. That is, the repeating structural unit represented by formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

Examples of the tetracarboxylic acid compound include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydride; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compound may be used alone, or two or more kinds may be used in combination. As for the tetracarboxylic acid compound, in addition to the dianhydride, it may also be a tetracarboxylic acid compound related substance such as an acetyl chloride compound.

Specific examples of the aromatic tetracarboxylic dianhydride include: 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2 ,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyl Tetracarboxylic dianhydride, 3,3',4,4'-diphenylbenzene tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4'-(hexafluoroisopropylidene) di Phthalic dianhydride (6FDA), 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl )Methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride and 4,4'-(p-phenylenedioxy) diphthalic dianhydride and 4,4'-(m-extended phenyl Dioxy) diphthalic dianhydride. These can be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic dianhydride include cyclic or acyclic aliphatic tetracarboxylic dianhydride. The cycloaliphatic tetracarboxylic dianhydride is tetracarboxylic dianhydride having an alicyclic hydrocarbon structure. Specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, Cycloalkane tetracarboxylic dianhydride such as 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride, bicyclo[2.2.2]octane -7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride and positional isomers of these. These can be used alone or in combination of two or more. Specific examples of the non-cyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butane tetracarboxylic dianhydride, 1,2,3,4-pentane tetracarboxylic dianhydride, etc., These can be used alone or in combination of two or more. In addition, cyclic aliphatic tetracarboxylic dianhydride and non-cyclic aliphatic tetracarboxylic dianhydride may be used in combination.

Among the above-mentioned tetracarboxylic dianhydrides, from the viewpoint of high transparency and low colorability, 1,2,4,5-cyclohexanetetracarboxylic dianhydride and bicyclo[2.2.2]octane are preferred -7-ene-2,3,5,6-tetracarboxylic dianhydride and 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof. In addition, as the tetracarboxylic acid, an aqueous adduct of the anhydride of the above-mentioned tetracarboxylic acid compound can also be used.

Examples of the tricarboxylic acid compounds include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and related acetyl chloride compounds, acid anhydrides, and the like, and two or more types may be used in combination. Specific examples include: 1,2,4-benzenetricarboxylic acid anhydride; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; phthalic anhydride and benzoic acid using a single bond,- A compound formed by connecting CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or phenylene.

Examples of the dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and related acetyl chloride compounds, acid anhydrides, and the like, and two or more of these may be used in combination. As specific examples of these, terephthalic acid dichloride (terephthaloyl chloride (TPC)); isophthalic acid dichloride; naphthalene dicarboxylic acid dichloride; 4,4'-biphenyl Dicarboxylic acid dichloride; 3,3'-biphenyl dicarboxylic acid dichloride; 4,4'-oxybis(benzoyl chloride) (OBBC); dicarboxylic acid of chain hydrocarbons with carbon number below 8 The acid compound and the two benzoic acids are compounds in which single bonds -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or phenylene are linked.

Examples of the diamines include aliphatic diamines, aromatic diamines, and mixtures of these. In addition, in the present embodiment, "aromatic diamine" means a diamine in which an amine group is directly bonded to an aromatic ring, and an aliphatic group or other substituent may be included in a part of its structure. The aromatic ring may be a single ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a stilbene ring, but are not limited thereto. Among these, the aromatic ring is preferably a benzene ring. In addition, "aliphatic diamine" means a diamine in which an amine group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be included in a part of its structure.

Examples of the aliphatic diamine include non-cyclic aliphatic diamines such as hexamethylene diamine, 1,3-bis(aminomethyl)cyclohexane, and 1,4-bis(aminomethyl). Cycloaliphatic diamines such as cyclohexane, noranediamine, 4,4'-diaminodicyclohexylmethane, etc. These can be used alone or in combination of two or more.

Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 2 , 6-diaminonaphthalene and other aromatic diamines with one aromatic ring; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diamine Diphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diamine Diphenyl sulfone, 3,3'-diamino diphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-Diaminodiphenyl satin, bis[4-(4-aminophenoxy)phenyl] satin, bis[4-(3-aminophenoxy)phenyl] satin, 2 ,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethyl Benzidine, 2,2'-bis(trifluoromethyl) benzidine (2,2'-bis(trifluoromethyl)-4,4'-diaminobenzyl (TFMB)), 4,4 '-Bis(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl) stilbene, 9,9-bis(4-amino-3-methylphenyl) stilbene, Aromatic diamines with more than 2 aromatic rings such as 9,9-bis(4-amino-3-chlorophenyl) stilbene, 9,9-bis(4-amino-3-fluorophenyl) stilbene, etc. These can be used alone or in combination of two or more.

Among the above-mentioned diamines, from the viewpoint of high transparency and low colorability, it is preferable to use one or more kinds selected from the group consisting of aromatic diamines having a biphenyl structure, and it is more preferable to use Free 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4'- One or more of the diamine diphenyl ether group is more preferably 2,2'-bis(trifluoromethyl) benzidine.

The polyimide-based resin can be obtained by mixing the raw materials such as the above-mentioned diamine, tetracarboxylic acid compound, tricarboxylic acid compound, and dicarboxylic acid compound by a conventional method such as stirring, and thereafter, The obtained intermediate is imidate in the presence of an imidate catalyst and optionally a dehydrating agent. Polyamide-based resins can be obtained by mixing various raw materials such as the above-mentioned diamines and dicarboxylic acid compounds by a conventional method such as stirring.

The imidate catalyst used in the imidate step is not particularly limited, and examples thereof include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; N -Alicyclic amines (monocyclic) such as ethyl piperidine, N-propyl piperidine, N-butyl pyrrolidine, N-butyl piperidine, and N-propyl hexahydropyridine; azabicyclic [2.2.1]Heptane, azabicyclo[3.2.1]octane, azabicyclo[2.2.2]octane, and azabicyclo[3.2.2]nonane and other alicyclic amines (polycyclic ); and 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-lutidine, 2, Aromatic amines such as 4,6-trimethylpyridine, 3,4-cyclopentenepyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline.

The dehydrating agent used in the amide imidization step is not particularly limited, and examples thereof include acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, and isovaleric anhydride.

In the mixing of each raw material and the amide imidization step, the reaction temperature is not particularly limited, for example, 15 to 350°C, preferably 20 to 100°C. The reaction time is also not particularly limited, and is, for example, about 10 minutes to 10 hours. The reaction can be carried out under inert environment or under reduced pressure as required. In addition, the reaction may be carried out in a solvent. Examples of the solvent include those exemplified as solvents used for preparing varnishes. After the reaction, the polyimide-based resin or the polyamide-based resin is purified. As a purification method, for example, a method of adding a poor solvent to the reaction solution, precipitating the resin by reprecipitation method, and drying the precipitate is taken out, and if necessary, the precipitate is washed with a solvent such as methanol and then dried, etc. . In addition, for the production of the polyimide-based resin, for example, the production method described in Japanese Patent Laid-Open No. 2006-199945 or Japanese Patent Laid-Open No. 2008-163107 can be referred to. In addition, commercially available products may be used for the polyimide-based resin. Specific examples thereof include Neopulim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd., and KPI-MX300F manufactured by Kawamura Industries Co., Ltd. and the like.

The weight average molecular weight (Mw) of the polyimide-based resin or the polyamidoamine-based resin is preferably 200,000 or more, more preferably 250,000 or more, and further preferably 300,000 or more, and preferably 600,000 or less, more preferably 500,000 or less . There is a tendency that the greater the weight-average molecular weight of the polyimide-based resin or the polyamide-based resin, the easier it is to exhibit higher bending resistance during film formation. Therefore, from the viewpoint of improving the bending resistance of the transparent resin film, the weight average molecular weight is preferably at least the above lower limit. On the other hand, there is a tendency that the smaller the weight average molecular weight of the polyimide-based resin or the polyamide-based resin, the easier it is to reduce the viscosity of the varnish and the easier it is to improve the processability. In addition, there is a tendency that the stretchability of the polyimide-based resin or the polyamide-based resin is more easily improved. Therefore, from the viewpoint of workability and extensibility, it is preferable that the weight average molecular weight is equal to or less than the above upper limit. In addition, in this application, the weight average molecular weight can be measured by gel permeation chromatography (GPC) and converted by standard polystyrene conversion, for example, by the method described in the examples.

The imidate ratio of the polyimide-based resin is preferably 95 to 100%, more preferably 97 to 100%, still more preferably 98 to 100%, and particularly preferably 100%. From the viewpoint of the stability of the varnish and the mechanical properties of the obtained transparent resin film, it is preferable that the imidate ratio is equal to or higher than the above lower limit. In addition, the imidate ratio can be obtained by IR (Infrared Radiation, Infrared) method, NMR (Nuclear Magnetic Resonance) method, and the like. From the above viewpoint, it is preferable that the polyimide-based resin contained in the varnish has an imidate ratio within the above range. The above-mentioned imidate ratio can be obtained by the method described in Japanese Patent Application No. 2018-007523, for example.

In a preferred embodiment of the present invention, the polyimide-based resin or polyamide-based resin contained in the transparent resin film of the present invention contains, for example, a halogen such as a fluorine atom that can be introduced through the above-mentioned fluorine-containing substituent or the like Just atoms. When the polyimide-based resin or the polyamido-based resin contains halogen atoms, it is easy to increase the elastic modulus of the transparent resin film and reduce the yellowness (YI value). If the elastic modulus of the transparent resin film is high, it is easy to suppress the film from scratches and wrinkles, and if the yellowness of the transparent resin film is low, the transparency of the film is easily improved. The halogen atom is preferably a fluorine atom. Examples of preferred fluorine-containing substituents for containing a polyimide-based resin or polyamidide-based resin with a fluorine atom include a fluorine group and a trifluoromethyl group.

The content of halogen atoms in the polyimide-based resin or polyamidide-based resin is preferably 1 to 40% by mass based on the mass of the polyimide-based resin or polyamidide-based resin, and more preferably 5 to 40% by mass, more preferably 5 to 30% by mass. If the content of halogen atoms is 1% by mass or more, the elastic modulus at the time of filming will be further increased, the water absorption rate will be lowered, and the yellowness (YI value) will be further reduced, so that the transparency will be further improved. If the content of halogen atoms is 40% by mass or less, synthesis may be easy.

In one embodiment of the present invention, the content of the polyimide-based resin and/or the polyamide-based resin in the transparent resin film is preferably 40% by mass or more based on the total mass of the transparent resin film. It is more preferably 50% by mass or more, and further preferably 70% by mass or more. From the viewpoint of easy improvement of bending resistance and the like, it is preferable that the content of the polyimide-based resin and/or the polyamide-based resin is at least the above lower limit. In addition, the content of the polyimide-based resin and/or the polyamide-based resin in the transparent resin film is generally 100% by mass or less based on the total mass of the transparent resin film.

[additive] The transparent resin film of the present invention may further contain additives such as fillers. Examples of such additives include silicon dioxide particles, ultraviolet absorbers, whitening agents, silicon dioxide dispersants, antioxidants, pH adjusters, and leveling agents.

(Silica particles) The transparent resin film of the present invention may further contain silica particles as additives. The content of silicon dioxide particles is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and preferably 60 parts by mass with respect to 100 parts by mass of the transparent resin film. Below, it is more preferably 50 parts by mass or less, and still more preferably 45 parts by mass or less. In addition, the content of silicon dioxide particles can be selected from any combination of any of the upper limit and the lower limit. If the content of silicon dioxide particles is within the numerical range of the upper limit and/or the lower limit, there is a tendency that in the transparent resin film of the present invention, the silicon dioxide particles are less likely to aggregate and are uniformly in the state of primary particles Because of dispersion, the visibility of the transparent resin film of the present invention can be suppressed from decreasing.

The particle size of the silicon dioxide particles is preferably 1 nm or more, more preferably 3 nm or more, and further preferably 5 nm or more, particularly preferably 8 nm or more, and preferably 30 nm or less, more preferably 28 nm or less It is further preferably 25 nm or less, and particularly preferably 20 nm or less. The particle size of the silicon dioxide particles can be selected from any combination of the upper limit and the lower limit. If the content of silicon dioxide particles is in the numerical range of the upper limit and/or the lower limit, the transparent resin film of the present invention is less likely to interact with light of a specific wavelength in white light, so the transparency can be suppressed The visibility of the resin film is reduced. In this specification, the particle size of silica particles means the average primary particle size. The particle size of the silicon dioxide particles in the transparent resin film can be measured based on the captured image using a transmission electron microscope (TEM). The particle size of the silica particles before the transparent resin film is made (for example, before being added to the varnish) can be measured by a laser diffraction particle size distribution meter.

Examples of the form of silica particles include silica sol in which silica particles are dispersed in an organic solvent and the like, and silica powder prepared by a gas phase method. Among these, from the viewpoint of workability, silica sol is preferred.

The silica particles may be subjected to surface treatment, for example, silica particles obtained by displacing a water-soluble alcohol-dispersed silica sol with a solvent (more specifically, γ-butyrolactone, etc.). The water-soluble alcohol is an alcohol having 3 or less carbon atoms per hydroxyl group in one molecule of the water-soluble alcohol, and examples thereof include methanol, ethanol, 1-propanol, and 2-propanol. Although it depends on the compatibility of the type of silicon dioxide particles and the polyimide-based polymer, there is usually the following tendency: if the surface of the silicon dioxide particles is treated, it will interact with the polyimide-based polymer contained in the transparent resin film The compatibility of the polymer is improved and the dispersibility of the silica particles is improved, so that the decrease in visibility of the present invention can be suppressed.

(UV absorber) The transparent resin film of the present invention may further contain an ultraviolet absorber. For example, tri-based UV absorbers, benzophenone-based UV absorbers, benzotriazole-based UV absorbers, benzoate-based UV absorbers, cyanoacrylate-based UV absorbers, etc. may be mentioned. These can be used alone or in combination of two or more. Preferred commercially available ultraviolet absorbers include, for example, Sumika Chemtex (registered trademark) Sumisorb (registered trademark) 340, ADEKA (registered trademark) Adekastab (registered trademark) LA-31, and BASF JAPAN (produced) TINUVIN (registered trademark) 1577, etc. Regarding the content of the ultraviolet absorber, based on the mass of the transparent resin film of the present invention, it is preferably 1 phr or more and 10 phr or less, and more preferably 3 phr or more and 6 phr or less.

(Brightener) The transparent resin film of the present invention may further contain a whitening agent. Regarding the whitening agent, for example, when an additive other than the whitening agent is added, it may be added in order to adjust the color tone. Examples of the whitening agent include monoazo dyes, triarylmethane dyes, phthalocyanine dyes, and anthraquinone dyes. Among these, anthraquinone-based dyes are preferred. Examples of preferred commercially available brighteners include Macrolex (registered trademark) Violet B manufactured by Lanxess Corporation, Sumiplast (registered trademark) Violet B manufactured by Sumika Chemtex Co., Ltd., and Diaresin (registered trademark) manufactured by Mitsubishi Chemical Corporation. Registered trademark) Blue G, etc. These can be used alone or in combination of two or more. When the whitening agent is included, the content is based on the mass of the transparent resin film of the present invention, preferably 1 to 50 ppm, more preferably 1 to 45 ppm, further preferably 3 to 40 ppm, and more Preferably, it is 5 to 35 ppm.

The application of the transparent resin film of the present invention is not particularly limited, and can be used for various applications. The transparent resin film may be a single layer as described above, or may be a laminate. The transparent resin film may be used as it is, or it may be further used as a laminate with other films. Since this transparent resin film has excellent surface quality, it is effectively used as a transparent resin film for an image display device or the like.

The transparent resin film of the present invention is effectively used as a front panel of an image display device, especially a front panel (window film) of a flexible display. The flexible display includes, for example, a flexible functional layer, and the above-mentioned polyimide-based film that functions as a front panel overlaid on the flexible functional layer. That is, the front panel of the flexible display is disposed on the viewing side of the flexible functional layer. The front panel has the function of protecting the flexible functional layer.

[Manufacturing method of transparent resin film] The transparent resin film of the present invention is not particularly limited, for example, it can be manufactured by a method including the following steps: (a) a step of preparing a liquid (hereinafter sometimes referred to as varnish) containing the above resin and the above filler (varnish preparation step), (b) The step of applying a varnish on the substrate to form a coating film (coating step), and (c) A step of drying the applied liquid (coating film) to form a transparent resin film (transparent resin film forming step).

In the varnish preparation step, the varnish is prepared by dissolving the above resin in a solvent, adding the above filler and other additives as needed, and stirring and mixing. In addition, in the case of using silica as a filler, silica sol can also be added to the resin. The silica sol is a solvent that can dissolve the above resin, for example, the solvent used in the preparation of the following varnish. Dispersed by a dispersion of silica sol containing silica.

The solvent used for preparing the varnish is not particularly limited as long as it can dissolve the above resin. Examples of the solvent include: amide-based solvents such as N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide; γ-butyrolactone (GBL) and γ-pentane Lactone-based solvents such as lactones; sulfur-containing solvents such as dimethyl ash, dimethyl sulfoxide and cis-butane; carbonate-based solvents such as ethylene carbonate and propylene carbonate; and combinations of these. Among these, an amide-based solvent or a lactone-based solvent is preferred. These solvents can be used alone or in combination of two or more. In addition, the varnish may contain water, alcohol-based solvents, ketone-based solvents, acyclic ester-based solvents, ether-based solvents, and the like. The solid content concentration of the varnish is preferably 1 to 25% by mass, more preferably 5 to 20% by mass.

In the coating step, a varnish is coated on the substrate by a known coating method to form a coating film. Known coating methods include, for example, roll coating methods such as wire bar coating, reverse coating, and gravure coating, die coating methods, comma coating methods, and die lip coating ( lip-coating method, screen coating method, spray coating method, spray method, casting method, etc.

In the step of forming a transparent resin film, a long strip-shaped transparent resin film can be formed by drying the coating film and peeling it from the substrate. After peeling, a heat treatment step of drying the transparent resin film may be further performed. The heat treatment of the coating film can usually be performed at a temperature of 50 to 350°C. The coating film can be dried in an inert environment or under reduced pressure as required. In the heat treatment, the two ends of the long strip-shaped transparent resin film are held separately, while the film to be held is transported on one side, and the width of the film to be held is set to a specific distance on the one side, for example, while being transported in a dryer Heat treatment. At this time, the heat treatment of the transparent resin film can be performed by setting the ratio of the width of the film after heat treatment (except for the held portion) to the width of the film before heat treatment (except for the held portion) to 1.1 or less And release the holding of the resin film leaving the dryer. The ratio of the width of the film after heat treatment (except for the portion held) to the width of the film before heat treatment (except for the portion held) (hereinafter, sometimes referred to as the stretch magnification) is preferably 0.7 to 1.0, more preferably 0.7～0.98. Furthermore, since there is no extension from the portion where the film is held to the end of the film, it is excluded from the width of the film when calculating the stretch ratio. The holding of the membrane is performed by using a plurality of jigs at both ends of the membrane, for example. The plurality of clamps can be fixed on an endless chain of a specific length according to the size of the conveying device, so that the chain moves at the same speed as the film, and a clamp is set at an appropriate position of the chain, which will be transparent before entering the dryer The resin film is held and released at the time of leaving the dryer. The plurality of jigs provided at one end of the film is the space between the adjacent jigs, that is, the distance between the jig on the front side and the jig on the back side in the transport direction of the film is, for example, 1 to 50 mm, preferably 3 ～25 mm, more preferably 5～10 mmm. Also, align the straight line A orthogonal to the film transport axis with the center of the holding portion of any jig at one end of the film, at the intersection of the straight line A and the other end of the film, and the center of the holding portion of the jig at the above end, and the When the angle formed by the straight line B connected to the center of the holding portion of the jig closest to the intersection is θ, θ may be preferably 2° or less, more preferably 1° or less, and further preferably 0.5° or less. By setting θ to the above range, the optical properties such as the phase difference between the left and right of the film can be made uniform. If the ratio of the width of the film after heat treatment (which does not include a holding portion) to the width of the film before heat treatment (which does not include a holding portion) is within the above range, there is a tendency that the film appearance becomes good. In addition, the film may be fixed by a pin instead of a jig. The amount of solvent in the film after heat treatment is preferably 0.001 to 3% by mass, more preferably 0.001 to 2% by mass, further preferably 0.001 to 1.5% by mass, and particularly preferably 0.001 to, based on the mass of the film. 1.3% by mass. If the amount of solvent in the film after the heat treatment is within the above range, the appearance of the film tends to be good. At the end of the heat treatment, when the film leaves the dryer, the film is released from holding, preferably immediately cutting the film end. By cutting, the cracks that are easily generated between the end of the film between the holding portion and the unretained portion are removed from the film, thereby preventing the film from being transported afterwards. The film is cracked due to the temperature drop expand.

As an example of the base material, if it is a metal system, an endless belt made of SUS (Steel Use Stainless, Japan Stainless Steel Standard) can be cited; if it is a resin system, a long-strip PET (Polyethylene Terephthalate) Ethylene formate film, PEN (Polyethylene Naphthalate) film, other polyimide-based resin or polyamide resin film, cycloolefin polymer (COP) film, acrylic Membrane etc. Among them, from the viewpoint of excellent smoothness and heat resistance, PET films, COP films, and the like are preferable, and further, from the viewpoint of adhesion to a transparent resin film and cost, PET films are more preferable.

Protective film In the present invention, the transparent resin film may include a protective film attached to the transparent resin film in the form of a laminate. The protective film is attached to the unsupported surface of the transparent resin film. When there is a problem such as adhesion when the laminate is wound into a roll, the above content can be added, and a protective film can be attached to the surface of the support opposite to the transparent resin film. The protective film attached to the transparent resin film is a film for temporarily protecting the surface of the transparent resin film, and it is not particularly limited as long as it is a peelable film that can protect the surface of the transparent resin film. For example, polyester resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin resin films such as polyethylene and polypropylene films; acrylic It is preferably selected from the group consisting of polyolefin resin film, polyethylene terephthalate resin film, and acrylic resin film. When protective films are attached to both sides of the laminate, the protective films on each side may be the same or different.

The thickness of the protective film is not particularly limited, but it is usually 10 to 100 μm, preferably 10 to 80 μm. When a protective film is attached to both sides of the laminate, the thickness of the protective film on each side may be the same or different.

Laminated film roll In the present invention, the layered product (support, transparent resin film, and optional protective film) wound around the core in a roll form is called a layered film roll. Due to space and other constraints in the continuous production of laminate film rolls, most of them are temporarily stored in the form of film rolls, and the laminate film roll is also one of them.

Examples of the material constituting the core of the laminate film roll include polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyester resin, epoxy resin, phenol resin, melamine resin, silicone resin, and polyurethane. Synthetic resins such as ester resins, polycarbonate resins, ABS (acrylonitrile-butadiene-styrene resin) resins; metals such as aluminum; fiber-reinforced plastics (FRP: plastics contain glass fibers Composite materials such as fibers to increase strength). The winding core is formed into a cylindrical shape or a cylindrical shape, and the diameter thereof is, for example, 80 to 170 mm. In addition, the diameter of the film roll (diameter after winding) is not particularly limited, but is usually 200 to 800 mm.

After the protective film is attached to the transparent resin film, it can be cut to a desired width. [Example]

Hereinafter, the effects of the present invention will be made clearer by examples. Furthermore, the present invention is not limited to the following embodiments, and can be implemented with appropriate changes without changing the scope of the gist.

(Weight average molecular weight) Determination by gel permeation chromatography (GPC) (1) Pretreatment method The sample was dissolved in γ-butyrolactone (GBL) to prepare a 20% by mass solution, which was then diluted to 100 times with a DMF eluent, filtered with a 0.45 μm membrane filter, and the obtained was used as a measurement solution. (2) Measurement conditions Column: TSKgel SuperAWM-H×2＋SuperAW2500×1 (6.0 mm I.D.×150 mm×3 pieces) Dissolution solution: DMF (addition of 10 mmol/L lithium bromide) Flow rate: 0.6 mL/min Detector: RI (Refractive Index, refractive index) detector Column temperature: 40℃ Injection volume: 20 μL Molecular weight standard: standard polystyrene

<Measurement of the imidate ratio> The imidate ratio of the polyimide resin and the polyimide resin used in the examples and comparative examples was measured by ¹ H-NMR using the formula ( Calculate the signal of the partial structure represented by XXX). The measurement conditions and the method of calculating the imidate ratio based on the obtained results are as follows.

(Measurement conditions of NMR) Measuring device: 600 MHz NMR device AVANCE600 manufactured by Bruker Sample temperature: 303 K Measuring method: ¹ H-NMR, HSQC

(Calculation method of polyimide resin's imidization ratio) In the ¹ H-NMR spectrum obtained by using a solution containing polyimide resin as a measurement sample, the proton derived in formula (XXX) is derived The integral value of the signal of (A) is set to Int _A , and the integral value of the signal derived from the proton (B) is set to Int _B. Based on these values, the imidate ratio (%) was determined by the following formula (NMR-1).

<Measurement of total light transmittance (Tt)> The total light transmittance of the transparent resin film is measured in accordance with JIS K 7105:1981 by a fully automatic direct-read Haze Computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd. The results are shown in Table 3.

<Measurement of Haze> The haze of the transparent resin film was measured in accordance with JIS K 7105:1981 by a fully automatic direct-read Haze Computer HGM-2DP manufactured by Suga Test Instruments (Co., Ltd.). The results are shown in Table 3.

<Measurement of Yellowness (YI)> The yellow index (yellowness: YI value) of the transparent resin film was measured by an ultraviolet-visible near-infrared spectrophotometer V-670 manufactured by Japan Spectroscopy Corporation. The background measurement was carried out without a sample, and then, a transparent resin film was set in the sample holder, and the transmittance measurement for light of 300 to 800 nm was performed to obtain tristimulus values (X, Y, Z). The YI value is calculated based on the following formula. YI value=100×(1.2769X－1.0592Z)/Y The results are shown in Table 3.

<Measurement of the amount of residual solvent> Using TG-DTA (EXSTAR6000 TG/DTA6300 manufactured by SII), the transparent resin films obtained in Examples 1 and 2 and Comparative Examples and 2 were heated from 30°C to 120°C and kept at 120°C for 5 minutes. Thereafter, the temperature was raised to 400°C at a rate of 5°C/min. The ratio of the decrease in the mass of the film from 120°C to 250°C relative to the mass of the film at 120°C was calculated as the content of the solvent (referred to as the amount of residual solvent). The results are shown in Table 3.

<Crack> At the position where the membrane is away from the jig, visually confirm that the membrane is flowing for 50 m, and check for cracks. The results are shown in Table 2.

<Appearance> At the position where the film leaves from the jig, visually confirm the film during the 50 m flow period to visually confirm whether the film is broken and whether there are surface ripples (such as galvanized iron skin-like defects) such as galvanized iron skin. The results are shown in Table 2.

<Production Example 1: Production of Polyimide Resin (1)> Prepare a flask equipped with a silica gel tube, a stirring device and a thermometer, and an oil bath in a separable flask. Put 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) 75.6 g and 2,2'-bis(trifluoromethyl)-4,4'-di in the flask Aminobiphenyl (TFMB) 54.5 g. While stirring it at 400 rpm, 530 g of N,N-dimethylacetamide (DMAc) was added, and stirring was continued until the contents of the flask became a uniform solution. Then, while adjusting with an oil bath so that the temperature in the container was in the range of 20 to 30° C., the stirring was continued for 20 hours to cause the reaction to produce polyamic acid. After 30 minutes, the stirring speed was changed to 100 rpm. After stirring for 20 hours, the temperature of the reaction system was returned to room temperature, and 650 g of DMAc was added for adjustment so that the polymer concentration became 10% by mass. Furthermore, 32.3 g of pyridine and 41.7 g of acetic anhydride were added, and the mixture was stirred at room temperature for 10.5 hours to perform amide imidization. Remove the polyimide varnish from the reaction vessel. The obtained polyimide varnish was added dropwise to methanol for reprecipitation, the obtained powder was heated and dried to remove the solvent, and the polyimide-based resin (1) was obtained as a solid component. GPC measurement was performed on the obtained polyimide-based resin (1), and as a result, the weight average molecular weight (Mw) was 365,000. In addition, the imidate ratio of polyimide was 99.0%.

<Production Example 2: Production of Polyimide Resin (2)) Under a nitrogen atmosphere, 45 g (140.52 mmol) of TFMB and 768.55 g of DMAc were added to a 1 L separable flask equipped with a stirring blade, and the TFMB was dissolved in DMAc while stirring at room temperature. Then, 6FDA 18.92 g (42.58 mmol) was added to the flask, and stirred at room temperature for 3 hours. After that, 4,4'-oxybis(benzyl chloride) (OBBC) 4.19 g (14.19 mmol) was added to the flask, followed by addition of terephthaloyl chloride (TPC) 17.29 g (85.16 mmol), and the mixture Stir at room temperature for 1 hour. Then, 4.63 g (49.68 mmol) of 4-methylpyridine and 13.04 g (127.75 mmol) of acetic anhydride were added to the flask, and stirred at room temperature for 30 minutes, after which the temperature was raised to 70°C using an oil bath, and the mixture was further stirred for 3.5 hours To obtain the reaction solution. The obtained reaction liquid was cooled to room temperature, put into a large amount of methanol in a filamentous form, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Then, the precipitate was dried under reduced pressure at 100°C to obtain a polyimide-based resin (2). The weight average molecular weight (Mw) of the polyimide-based resin (2) was 455,000. In addition, the imidate ratio of polyimide was 98.9%.

<Production Example 3: Production of Dispersion Liquid 1> Substitute methanol dispersed organic silicon dioxide (particle size measured by BET (Brunauer-Emmett-Teller, Buert) method: 27 nm) with γ-butyrolactone (GBL) to obtain GBL dispersed organic Handle silicon dioxide (solid content 30.3%). This dispersion liquid is referred to as dispersion liquid 1.

<Production Example 4: Production of varnish (1)> Varnish 1 was obtained by dissolving a polymer in a solvent with the composition shown in Table 1, and obtaining a varnish (1) having a solid content of 15.5% and a viscosity at 25°C of 36,500 calculated from the added amount.

<Production Example 5: Production of varnish (2)> Varnish 2 is mixed at room temperature in the GBL with a composition ratio of polymer to filler of 60:40, and to the total mass of polymer and silica of 5.7 phr or 35 ppm. Add Sumisorb 340 (UVA), Sumiplast Violet B (BA) and stir until it becomes homogeneous. A varnish (2) with a solid content of 10.3% and a viscosity of 38,500 at 25°C was obtained.

[Table 1]

<Production Example 6: Film formation of raw material film (1)> Put the varnish (1) on a PET (polyethylene terephthalate) film ("COSMOSHINE (registered trademark) A4100" manufactured by Toyobo Co., Ltd., film thickness 188 μm, film thickness distribution ±2 μm) by flow Extending forming the coating film. At this time, the coating film was dried under the following conditions: linear speed of 0.4 m/min, heating at 70°C for 8 minutes, then heating at 100°C for 10 minutes, then heating at 90°C for 8 minutes, and finally heating at 80°C for 8 minutes. Thereafter, the coating film was peeled off from the PET film to obtain a raw film 1 having a thickness of 86 μm and a width of 700 mm. The mass reduction rate M of the raw film 1 is 9.6%.

<Production Example 7: Film formation of raw material film (2)> Cast varnish (2) on PET (polyethylene terephthalate) film (Toyobo (share) "COSMOSHINE (registered trademark) A4100", film thickness 188 μm, film thickness distribution ±2 μm) by casting Shape the coating film. At this time, the line speed is 0.3 m/min. The coating film was dried under the following conditions: heating at 80°C for 10 minutes, then heating at 100°C for 10 minutes, then heating at 90°C for 10 minutes, and finally heating at 80°C for 10 minutes. After that, the coating film was peeled from the PET film to obtain a raw material film 2 having a thickness of 58 μm and a width of 700 mm. The mass reduction rate M of the raw material film 2 is 9.2%.

<Example 1> For the raw material film 1 obtained in Production Example 6, the solvent was removed using a tenter dryer (1 to 6-chamber configuration) using a jig as a holder to obtain a polyimide film 1 with a thickness of 79 μm. Set the temperature in the dryer to 200°C, set the holding width of the clamp to 25 mm, set the conveying speed of the film to 1.0 m/min, and adjust so that the film width at the outlet of the dryer is relative to the film at the inlet of the dryer The ratio of the width (distance between clamps) becomes 1.0, and the wind speed in each chamber of the tenter dryer is adjusted so that 1 chamber becomes 13.5 m/s, 2 chambers become 13 m/s, and 3 to 6 It becomes 11 m/s in the room. After the film was separated from the jig, the jig portion was cut off, a PET-based protective film was attached to the film, and wound up on a 6-inch core made of ABS to obtain a rolled film. Table 3 shows the optical properties of the obtained film and the amount of residual solvent.

<Example 2> A polyimide film 2 having a thickness of 49 μm was obtained in the same manner as in Example 1 except that the raw material film was changed to the raw material film (2) and the elongation ratio was changed to 0.98. Table 3 shows the optical properties of the obtained film and the amount of residual solvent.

<Example 3> A polyimide film with a thickness of 78 μm was obtained in the same manner as in Example 1 except that the ratio of the film width at the inlet of the dryer (distance between clamps) to the film width at the outlet of the dryer was adjusted to 1.02. 3. Table 3 shows the optical properties of the obtained film and the amount of residual solvent.

<Example 4> A polyimide film with a thickness of 49 μm was obtained in the same manner as in Example 2 except that the ratio of the film width at the inlet of the dryer (distance between clamps) to the film width at the outlet of the dryer was adjusted to 0.96. 4. Table 3 shows the optical properties of the obtained film and the amount of residual solvent.

<Comparative Example 1> A polyimide film 5 with a thickness of 48 μm was obtained in the same manner as in Example 2 except that the stretch magnification was changed to 1.3. Table 3 shows the optical properties of the obtained film and the amount of residual solvent.

<Comparative example 2> A polyimide film 6 having a thickness of 50 μm was obtained in the same manner as in Example 2 except that the stretch magnification was changed to 0.8. Table 3 shows the optical properties of the obtained film and the amount of residual solvent.

[Table 2]

[table 3]

(1)‧‧‧1 (2) Room ‧‧‧2 (3) Room ‧‧‧ (4) Room ‧‧‧‧ (5) Room ‧‧‧‧ (6) Room ‧‧‧ (a)‧‧‧Side view (b) ‧‧‧ top view

Fig. 1 shows an example of a dryer for manufacturing the transparent resin film of the present invention. It transports the film from the left side to the right side of the paper. (a) is a side perspective view of the dryer, and the center line is the state of the transported film. (b) shows a perspective view of the upper surface of the dryer, and the square in the center shows the state of the film being transported.

(1)‧‧‧1

(2) Room ‧‧‧2

(3) Room ‧‧‧

(4) Room ‧‧‧‧

(5) Room ‧‧‧‧

(6) Room ‧‧‧

(a)‧‧‧Side view

(b) ‧‧‧ top view

Claims (12)

A method for manufacturing a transparent resin film, comprising the steps of: forming a long strip-shaped transparent resin film containing at least one resin selected from the group consisting of polyimide-based resins and polyamide-based resins The two ends of each are held separately; the film to be held is transported; the width of the film to be held is set to a specific distance and the above-mentioned resin film is heat-treated in a dryer, and the width of the film after heat treatment is relative to that before heat treatment The ratio of the width of the film is set to 1.1 or less; and the retention of the resin film leaving the dryer is released. The manufacturing method according to claim 1, wherein the ratio of the width of the film after heat treatment to the width of the film before heat treatment is 0.7 to 1.0. The manufacturing method according to claim 1 or 2, wherein it is held by a plurality of jigs. The manufacturing method according to claim 3, wherein the driving device mounted with the jig is moved at the same speed as the transport speed of the film. The manufacturing method according to claim 4, wherein the driving device is driven by a chain. The manufacturing method according to any one of claims 3 to 5, wherein the space between adjacent clamps is 1 to 20 mm. The manufacturing method according to any one of claims 3 to 6, wherein when the straight line orthogonal to the film conveying axis is aligned with the center of the holding portion of any jig at one end of the film, the intersection point of the straight line and the other end of the film and the The distance between the center of the holding part of the jig closest to the intersection is 3 mm or less. The manufacturing method according to any one of claims 1 to 7, wherein the content of the organic solvent contained in the resin film after the heat treatment is 0.001 to 3% by mass relative to the mass of the resin film. The manufacturing method according to any one of claims 1 to 8, wherein there is a step of cutting both ends of the film after releasing the holding of the film. The manufacturing method according to claim 9, wherein after the film is cut, there is a step of bonding a protective film on the resin film. The manufacturing method according to claim 10, wherein after the protective film is attached, there is a step of cutting the resin film to which the protective film is attached. The manufacturing method according to claim 10 or 11, wherein after the protective film is attached, there is a step of winding the resin film into a roll.

Images