JPH0611615A - Retarder - Google Patents

Abstract

(57) [Summary] [Structure] A retardation plate comprising a glutarimide acrylic resin composed of 5 to 80 mol% of glutarimide structural units and 95 to 20 mol% of methyl methacrylate units. [Effects] The retardation plate of the present invention requires a field in which good optical properties and heat resistance are required, including a retardation plate for compensation of a black and white STN type liquid crystal display, and requires processing using a solvent. It is suitable for applications. Further, it can be used for producing a retardation plate which is excellent in optical properties and solvent resistance and does not depend on the incident angle of optical path difference rays.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retardation substrate having excellent transparency, durability, heat resistance and solvent resistance.

[0002]

2. Description of the Related Art Plastic retarders have become more and more important with the recent development of optical technology.
In an N-type liquid crystal display, it is used as a compensating retardation plate for compensating for coloring due to birefringence peculiar to liquid crystal to make it colorless. An anisotropic film or sheet of polycarbonate has been conventionally used as such a retardation plate. However, the retardation film of a polycarbonate resin has a drawback that the optical properties such as transparency and light resistance, which are particularly important properties in optical elements, are inferior, and the solvent resistance is poor and the use scene is limited. It was On the other hand, as a retardation plate excellent in transparency, light resistance, and solvent resistance, methyl methacrylate and other monomers such as acrylic acid ester, styrene, maleic anhydride, maleimide, N-substituted maleimide, etc. A retardation plate made of a so-called acrylic resin which is a copolymer resin is known, but it has a problem of low heat resistance. (Japanese Patent Application No. 1-157094) Furthermore, as a retardation plate with improved optical path difference variation depending on the incident angle, a retardation plate having a positive intrinsic birefringence value represented by a retardation plate of a polycarbonate resin and a negative retardation plate are negative. A retardation plate in which retardation plates are combined has been proposed (Japanese Patent Application No. 1-1599).
81), for this purpose, there has been a demand for a retardation plate having a positive intrinsic birefringence, which is improved from the drawbacks of the retardation plate made of a polycarbonate resin.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, that is, to develop a retardation plate excellent in transparency, light resistance, heat resistance and solvent resistance. This is a development of a retardation plate having a positive intrinsic birefringence with the above property.

[0004]

Means for Solving the Problems As a result of intensive studies made by the present inventors on the solution of the above problems, a retardation plate produced by uniaxially stretching or unbalanced biaxially stretching a certain resin having a glutarimide structural unit. However, they have found that they are excellent in transparency, light resistance, solvent resistance, and heat resistance, and that a retardation plate having a positive intrinsic birefringence can also be obtained, and completed the present invention.

That is, the object of the present invention is to use a glutarimide acrylic resin composed of 5 to 80 mol% of a glutarimide structural unit represented by the following general formula [1] and 95 to 20 mol% of a methyl methacrylate unit. It is achieved by a retardation plate characterized in that

[0006]

[Chemical 2] (However, in the formula [1], R is hydrogen, and the number of carbon atoms is 1 to 1.
It represents an alkyl group having 8 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms. )

[0007]

The retardation plate of the present invention is not only excellent in transparency and light resistance, but also a conventional acrylic retardation plate, that is, a so-called general-purpose retarder which is a copolymer of methyl methacrylate and alkyl acrylate. Acrylic resin, copolymer resin of methyl methacrylate and styrene, copolymer resin of thimel methacrylate and maleic anhydride or copolymer of N-substituted maleimide and styrene, etc. There is. For example, when heating for 30 minutes and comparing at a temperature where the change in intensity of the optical path difference remains within 0.5%,
Among the conventional acrylic resin retarders, one having the best heat resistance, methyl methacrylate unit 76% by weight, maleic anhydride unit 10% by weight, styrene unit 14
The phase difference plate of acrylic copolymer resin consisting of wt% is 110
Whereas R is hydrogen, the retardation plate of the present invention comprising a resin in which R is hydrogen and the content of the glutarimide structural unit is 25 mol% reaches 140 ° C.

Furthermore, the retardation plate of the present invention is also excellent in solvent alignment. For example, in a resistance test to butyl acetate and toluene used for printing ink, a retardation plate of a polycarbonate resin is whitened, whereas no change is observed in the retardation plate of the present invention. It can be used for various purposes.

In addition, all of the conventional retardation plates of so-called acrylic resin containing methyl methacrylate as a main component show a negative intrinsic birefringence, that is, a property that the refractive index in the stretching direction decreases, and a positive intrinsic birefringence. That is, a retardation plate showing the property of increasing the refractive index in the stretching direction by stretching has not been obtained. However, surprisingly, for example, the general formula [1]
The retardation plate of the present invention in which R is hydrogen or a methyl group shows positive intrinsic birefringence even though it is an acrylic resin retardation film, and has optical properties, solvent resistance, and heat resistance. Excellent positive retardation plate has become possible.

This is used as a positive retardation plate and a conventional retardation plate of a methyl methacrylate copolymer resin is combined as a negative retardation plate to use polycarbonate as a conventional positive retardation plate. Improved transparency,
A retardation plate that has excellent light resistance and solvent resistance and has little dependence on the incident angle of the optical path difference has become possible. Furthermore, the positive intrinsic birefringence can be made negative by changing R in the general formula [1] if necessary, and further by combining the positive and negative retardation plates of the present invention, A retardation plate having excellent heat resistance and less dependence of the optical path difference on the incident angle is possible.

It is essential that the glutarimide acrylic resin (hereinafter abbreviated as glutarimide resin) which is the base resin of the film or sheet of the present invention comprises a glutarimide structural unit and a methyl methacrylate unit. R of the glutarimide structure is hydrogen, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, and hydrogen, a methyl group, a cyclohexyl group, phenyl A group is mentioned as a preferable thing, Especially a hydrogen and a methyl group are preferable. When the carbon number is large, the heat resistance is poor.

The content of the glutarimide structural unit is 5 to 8
It is 0%, preferably 10 to 75%, and when the content is too small, the Tg of the resin is lowered and the heat resistance of the retardation plate of the present invention cannot be achieved. If the content is too large, the workability is poor and the retardation plate is difficult to manufacture, such as breaking during stretching. In addition, due to the resin manufacturing method, an amide structure and the like will remain in the polymer chain, and coloring during molding is undesirable.

The methyl methacrylate unit is necessary for achieving the features of the retardation plate of the present invention such as transparency and light resistance.

Other monomer units such as methacrylic acid ester, methyl acrylate and ethyl acrylate may be contained within a range not impairing the effects of the present invention.

The molecular weight of the glutarimide resin is preferably 60 to 150,000 (in terms of polystyrene). When the molecular weight is low, the mechanical strength is insufficient, and when it is too high, the moldability such as stretchability is deteriorated, which is not preferable.

A resin modifier such as a plasticizer, a colorant, an ultraviolet absorber, an antioxidant, and a lubricant is added to the glutarimide resin within a range not impairing the effects of the present invention, or another resin is blended. can do.

The glutarimide resin is obtained by radical polymerization of methyl methacrylate and N-substituted methacrylamide or / and methacrylamide in methanol,
The obtained copolymer can be produced by cyclizing in the presence of sodium methoxide. Specifically, JP-A-2-
The method of No. 153904 is mentioned as a preferable production example.

The retardation plate of the present invention can be produced, for example, by producing an unstretched film or sheet by extrusion molding a glutarimide resin and stretching it.

The stretching method is selected from free-width uniaxial stretching, constant-width uniaxial stretching, and unbalanced biaxial stretching in accordance with the required optical path difference strength and the angle dependence of the optical path difference. The stretching temperature is 10 ° C higher than the Tg of the resin to 40 ° C higher than the Tg.
The temperature range of higher temperature is appropriate. If it is too low, the stretching is difficult, and if it is too high, the optical path difference strength is low. The draw ratio is selected from 1.05 to 3.5 times, particularly 1.2 to 2.
5 times is suitable. If it is too small, it is difficult to control the intensity of the optical path difference, and if it is too large, it tends to break and the unevenness of the intensity of the optical path difference becomes large. The stretching speed is usually 100 to 50.
00% / min is used. Generally, it is cooled immediately after completion of stretching.

The optical path difference of the retardation plate of the present invention is selected according to the application. For example, 5-50 nm for fine adjustment of optical path difference,
A quarter-wave plate with a thickness of about 150 nm and a range of 150 to 700 nm is often used for liquid crystal display retardation compensation.

The thickness of the retardation plate of the present invention is not essentially limited, but it is 10 in terms of manufacturing and handling.
μ to 1 mm, especially 20 to 500 μ is preferable. If the thickness is thin, it is easily broken during molding, and if the thickness is too thin or too thick, handling during use becomes difficult.

In the present invention, a film having a thickness of less than 254 μ is distinguished from a film having a thickness of 254 μ or more.

The method of measuring the characteristic values used in the description of the present invention will be described below.

Optical path difference measurement method: Measurement was carried out by a conventional method using a polarization microscope (LABOPHOT-POL, manufactured by Nippon Kogaku Co., Ltd.). -Transparency: Total light transmittance and haze are evaluated.

Measured according to ASTM D1003.

Heat resistance: The optical path difference intensity change was measured by heating for 30 minutes in a forced-air circulating constant temperature oven kept at a predetermined temperature.

Molecular weight: Determined by GPC measurement in comparison with polystyrene molecular weight standard product (in terms of polystyrene).

Solvent resistance evaluation: Butyl acetate and toluene used as the solvent for the printing ink are selected, one end of the test piece is immersed in the solvent for 0.1 to 0.2 seconds, immediately taken out, and left to dry in the air. did. It was evaluated by the presence or absence of whitening and other changes.

[0029]

EXAMPLES The present invention will be specifically described with reference to examples. Example 1 By using a graphographic biaxial stretching tester {manufactured by Toyo Seiki Co., Ltd.}, a stretching temperature of 170 ° C., a stretching speed of 1000% / min,
It was uniaxially stretched with a constant width at a stretch ratio of 1.75 to produce a retardation plate having a thickness of 401μ. The optical path difference of this retardation plate is 4
It was 39 nm.

The transparency was good with a total light transmittance of 93% and a haze of 0.3%. Even when heated at 140 ° C. for 30 minutes, the optical path difference was 438 nm, which was almost unchanged. The solvent resistance to butyl acetate and toluene was good without whitening or other changes.

In addition, a strain detector {SV manufactured by Toshiba Glass Co., Ltd.
When the relationship between the stretching direction and the color change was compared with that of the polycarbonate retardation plate by the sensitive color plate method (P-10-P type), it was a retardation plate having positive intrinsic birefringence. Comparative Example 1 An extruder having an acrylic copolymer resin (molecular weight: 120,000) consisting of 76% by weight of a methyl methacrylate unit, 10% by weight of a maleic anhydride unit and 14% by weight of a styrene unit and having a cylinder diameter of 20 mm at an extrusion temperature of 250 ° C. Extruded with about 50
A 0 μ unstretched sheet was prepared. In the same manner as in Example 1, the stretching temperature of 140 ° C., the stretching speed of 1000% / min,
It was uniaxially stretched with a constant width at a stretch ratio of 1.5 times to prepare a retardation plate having a thickness of 332μ. The optical path difference of this retardation plate is 13
It was 8 nm. It changed to 137 nm by heating at 110 ° C. for 30 minutes, and decreased to 124 nm at 120 ° C. Comparative Example 2 Polycarbonate resin {made by Idemitsu Petrochemical Co., Ltd., A-2
500} at an extrusion temperature of 280 ° C and a cylinder diameter of 20 nm
Was extruded by an extruder to prepare an unstretched sheet of about 700μ. Using a paragraph biaxial stretching critical testing machine {manufactured by Toyo Seiki Co., Ltd.}, draw it at a stretching temperature of 180 ° C., 1000
A retardation plate having a thickness of 397 μ was produced by uniaxially stretching a given width at a stretching rate of% / min and a stretching ratio of 1.75 times. The optical path difference of this retardation plate was 401 nm. The transparency was inferior in that the total light transmittance was 90% and the haze was 0.7%. Also, it was whitened in a solvent resistance test with butyl acetate and toluene. Example 2 R of the glutarimide ring is hydrogen, the content of the glutarimide structural unit is 15 mol%, and the methyl methacrylate unit is 8
A glutarimide resin (Tg of 138 ° C.) having a molar ratio of 5 mol% and a molecular weight of 75,000 was extrusion-molded at an extrusion temperature of 275 ° C. with an extruder having a cylinder diameter of 20 mm to prepare an unstretched sheet of about 200 μ. did. In the same manner as in Example 1, 16
Stretching temperature of 0 ° C., stretching rate of 1000% / min, 1.75
The retardation plate having a thickness of 117 μ was produced by uniaxially stretching the film with a constant width at a stretch ratio of 2 times. The optical path difference of this retardation plate was 148 nm. As for transparency, the total light transmittance is 93% and the haze is 0.
It was as good as 1%. The solvent resistance to butyl acetate and toluene was good without whitening or other changes. 1
When heated at 30 ° C. for 30 minutes, the optical path difference was 147 nm, which was almost unchanged. Example 3 A glutarimide resin in which R of the glutarimide ring is a methyl group, the content of the glutarimide structural unit is 68 mol%, the methyl methacrylate unit is 32 mol%, and the molecular weight is 95,000 is 280 ° C. Cylinder diameter is 20 at extrusion temperature
An unstretched sheet of about 400μ was produced by extrusion molding with a mm extruder. In the same manner as in Example 1, a retardation plate having a thickness of 266 μ was produced by uniaxially stretching the film at a stretching temperature of 160 ° C., a stretching speed of 1000% / min and a stretching ratio of 1.5 times with a constant width. The optical path difference of this retardation plate was 245 nm. The transparency was good with total light transmittance of 93% and haze of 0.3%. The solvent resistance to butyl acetate and toluene was good without whitening or other changes. After heating at 130 ° C. for 30 minutes, the optical path difference was 245 nm and remained unchanged. Example 4 An unstretched sheet having a thickness of about 250 μm was produced from the resin used in Example 1 by the same operation as in Example 1. this,
Stretching temperature of 170 ° C., stretching rate of 1000% / min 2.0
The retardation plate having a thickness of 127 μ was produced by uniaxially stretching the film with a constant width at a stretch ratio of 2 times. The optical path difference of this retardation plate was 181 nm. As for transparency, the total light transmittance is 93% and the haze is 0.
It was as good as 3%. Even after heating at 140 ° C. for 30 minutes, the optical path difference was 180 nm, which was almost unchanged.

Further, a strain inspector {SV manufactured by Toshiba Glass Co., Ltd.
When the relationship between the stretching direction and the color change was compared with that of the polycarbonate retardation plate by the sensitive color plate method (P-10-P type), it was a retardation plate having positive intrinsic birefringence.

The acrylic resin used in Comparative Example 1 was uniaxially stretched at a constant draw width of 140 ° C. and a draw ratio of 2 to produce an intrinsic birefringent retardation plate having a thickness of 198 μ and an optical path difference of 183 nm. Were bonded so as to be orthogonal to each other to produce a laminated retardation plate having an optical path difference of 363 nm. In this laminated retardation plate, the optical path difference was 357 nm and the angle dependence of the optical path difference was small even if the incident angle of the light beam was inclined 45 degrees from the vertical direction to the stretching direction side of the phase difference plate of the present invention.

On the other hand, when the retardation plates used for the combination are inclined at an incident angle of light rays by 45 ° from the vertical direction to the stretching direction side, the optical path difference of the retardation plate of the present invention is 181 nm to 134 nm, and a negative acrylic retardation. The optical path difference of the plate is 183nm to 137nm
Then, the optical path difference changed depending on the incident angle of the light beam.

The transparency of the combined retardation plate was good, with a total light transmittance of 91% and a haze of 0.5%. The solvent resistance to butyl acetate and toluene was good without whitening or other changes. Comparative Example 3 Polycarbonate resin {made by Idemitsu Petrochemical Co., Ltd., A-2
From 500} to 180 ° C., a polycarbonate retardation plate having a thickness of 180 μ and an optical path difference of 183 nm produced by uniaxial stretching with a constant width at a draw ratio of 2 times, and an intrinsic birefringence having an optical path difference of 183 nm produced in Example 4. A negative retardation plate was adhered so that the stretching directions were orthogonal to each other, and a laminated retardation plate having an optical path difference of 363 nm was produced. This laminated retardation plate has an optical path difference of 348 nm and little angle dependence of the optical path difference even if the incident angle of the light rays is inclined 45 degrees from the vertical direction to the stretching direction side of the polycarbonate phase difference plate, but the transparency is Total light transmittance is 8
The haze was inferior at 8% and 0.9%. Also, it was whitened in a solvent resistance test with butyl acetate and toluene. Example 5 An unstretched sheet having a thickness of about 120 μ was prepared from the resin used in Example 1 by the same operation as in Example 1. this,
Stretching temperature of 170 ° C., stretching rate of 1000% / min, 2.
The retardation plate having a thickness of 74 μ was manufactured by uniaxially stretching with a free width at a draw ratio of 2 times. The optical path difference of this retardation plate was 142 nm. No change in optical path difference was observed even after heating at 140 ° C. for 30 minutes. Example 6 An unstretched sheet having a thickness of about 500 μ was prepared from the resin used in Example 1 by the same operation as in Example 1. this,
1. At a draw temperature of 180 ° C. and a draw speed of 1000% / min, first 1.1 times, then 2. perpendicular to the first draw direction.
Sequential stretching was carried out at a stretch ratio of 5 times to prepare a retardation plate having a thickness of 184μ. The optical path difference of this retardation plate is 105 nm
Met. No change in optical path difference was observed even after heating at 140 ° C. for 30 minutes. Example 7 Extruding temperature of a glutarimide resin having a glutarimide ring R of a phenyl group, a glutarimide structural unit content of 15 mol%, a methyl methacrylate unit of 85 mol% and a molecular weight of 80,000 at 285 ° C. Was extruded with an extruder having a cylinder diameter of 20 nm to prepare an unstretched sheet of about 200 μm. As in Example 1, a stretching temperature of 190 ° C., 5
A retardation plate having a thickness of 164μ was produced by uniaxially stretching a constant width at a stretching rate of 00% / min and a stretching ratio of 1.3 times. The optical path difference of this retardation plate was 43 nm. After heating at 140 ° C. for 30 minutes, no change was observed in the optical path difference.

[0036]

EFFECTS OF THE INVENTION A retarder made of a glutarimide resin composed of a glutarimide structural unit and a methyl methacrylate unit enables a retarder excellent in transparency, durability, heat resistance and solvent resistance. In addition, an acrylic positive retardation plate with intrinsic birefringence has become possible. INDUSTRIAL APPLICABILITY The retardation plate of the present invention is suitable for fields requiring good optical properties and heat resistance, such as a retardation plate for compensation of black and white STN type liquid crystal display, and applications requiring processing using a solvent. Is. Further, it can be used for producing a retardation plate having excellent optical properties and solvent resistance and having no dependence of optical path difference on the incident angle of light rays.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 2, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retardation plate having excellent transparency, durability, heat resistance and solvent resistance.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Furthermore the retardation plate of the present invention is also excellent in solvent resistance. For example, in a resistance test to butyl acetate and toluene used for printing ink, a retardation plate of a polycarbonate resin is whitened, whereas no change is observed in the retardation plate of the present invention. It can be used for various purposes.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

The thickness of the retardation plate of the present invention is not essentially limited, but is 10 μm from the viewpoint of manufacturing and handling.
˜1 mm, especially 20 μ to 500 μ is preferable. If the thickness is thin, it is easily broken during molding, and if the thickness is too thin or too thick, handling during use becomes difficult.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

Heat resistance: The change in optical path difference intensity was measured by heating for 30 minutes in a forced hot air circulation type constant temperature oven maintained at a predetermined temperature.

[0029]

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029]

EXAMPLES The present invention will be specifically described with reference to examples. Example 1 R of the glutarimide ring is hydrogen, and the glutarimide structure is simple.
Content of 25 mol%, methyl methacrylate unit is 7
Glutarimide tree with 5 mol% and a molecular weight of 90,000
Cylinder oil (Tg 150 ° C) at an extrusion temperature of 280 ° C
-Extruded with an extruder with a diameter of 20 mm,
A stretched sheet was produced. Thus a pantograph type biaxial stretching tester {manufactured by Toyo Seiki Co.}, stretching temperature of 170 ° C., of 1000% / min drawing speed, constant width uniaxial stretching at 1.75 times the draw ratio, of 401μ A retardation plate having a thickness was produced. The optical path difference of this retardation plate was 439 nm.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

This was used as a retardation plate having a negative intrinsic birefringence with a thickness of 198 μ and an optical path difference of 183 nm, which was produced by uniaxially stretching the acrylic resin used in Comparative Example 1 at 140 ° C. and a draw ratio of 2 at a constant width. Adhesion was performed so that the stretching directions were orthogonal to each other, and a laminated retardation plate having an optical path difference of 363 nm was produced. This laminated retardation plate has an optical path difference of 357 even if the incident angle of light rays is inclined 45 degrees from the vertical direction to the extending direction side of the retardation plate of the present invention.
nm and the optical path difference had little angle dependence. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 26, 1993

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

Heat resistance: The change in optical path difference intensity was measured by heating for 30 minutes in a forced hot air circulation type constant temperature oven maintained at a predetermined temperature.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshifumi Murata 2-28, Kurashiki-cho, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture Kuraray Co., Ltd.

Claims (2)

[Claims] 1. A glutarimide acrylic resin composed of 5 to 80 mol% of a glutarimide structural unit represented by the following general formula [1] and 95 to 20 mol% of a methyl methacrylate unit. Retardation plate. [Chemical 1] (However, in the formula [1], R is hydrogen, and the number of carbon atoms is 1 to 1.
It represents an alkyl group having 8 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms. ) 2. The retardation plate according to claim 1, wherein R in the general formula [1] is hydrogen or a methyl group, and the intrinsic birefringence is positive.