JP2009244609A - Method for manufacturing laminated optical film, laminated optical film, and application of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated optical film manufacturing method and a laminated optical film for displaying a uniform screen image of a liquid crystal display device by ensuring a high contrast ratio when the screen is viewed from oblique directions, and to provide a polarizer and a liquid crystal display device therewith. <P>SOLUTION: The laminated optical film manufacturing method includes steps of: (α) laminating a cyclic olefin resin (A) and a vinyl aromatic resin (B) by coextrusion to deposit a film; (β) drawing the coextrusion film to produce a laminated drawn film (C); and (γ) laminating the laminated drawn film (C) on a transparent resin film (D) to produce the laminated optical film (E). The laminated optical film (E) satisfies particular requirements. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a laminated optical film, a laminated optical film, and uses thereof. More specifically, the present invention relates to a method for producing a laminated optical film having a cyclic olefin resin layer and a vinyl aromatic resin layer, a laminated optical film, and uses thereof.

  The retardation film is generally used for the purpose of compensating the viewing angle of a liquid crystal display device, and functions to prevent light leakage at an oblique viewing angle and to prevent a decrease in contrast ratio. Examples of the optical film used as the retardation film include a polycarbonate film, a polyester film, a cellulose acetate film, and a cyclic olefin film.

Among these, the cyclic olefin film is excellent in transparency, heat resistance, dimensional stability, low photoelasticity, and the like, and thus has attracted attention as a material for various optical components including a retardation film.
In recent years, in addition to the conventional TN mode and STN mode, high viewing angle liquid crystal modes such as VA mode and IPS mode have been put into practical use, and liquid crystal display devices (liquid crystal televisions) have become widespread in television applications that require high image quality. ing.

  For example, an IPS (in-plane switching) mode liquid crystal display device has a wide viewing angle and high contrast in the front and up / down / left / right directions, but when the screen is viewed obliquely from a direction with an azimuth angle of 45 degrees, Since the angle formed by the absorption axis of the polarizing plate is not a right angle and light leaks, there is a problem that the light leaks during black display and the contrast is lowered. As a viewing angle compensation method using a phase difference film to solve this problem, Patent Document 1 discloses a compensation method using a heat shrink film and a film whose refractive index in the thickness direction is increased during stretching. Document 2 discloses a compensation method using a retardation layer of polymerizable liquid crystal having homeotropic alignment, and is known to be particularly effective in improving the viewing angle.

  However, the compensation method described in Patent Document 1 cannot be bonded to a polarizer by a roll-to-roll method because of the problem of increase in the number of processes and cost increase due to the use of a heat shrink film and the optical axis direction is limited. There's a problem. In addition, in the compensation method described in Patent Document 2, it is necessary to control a retardation layer made of a polymerizable liquid crystal with a thickness of about several microns with a thickness variation of several percent, and it is difficult to produce a uniform layer. In addition, there is a problem that it is necessary to ensure sufficient adhesion with the base film.

  As another viewing angle compensation method, Patent Document 3 discloses a transparent resin (monocyclic ring) on at least one side of a layer containing a resin (such as a vinyl aromatic polymer) having a negative intrinsic birefringence value. After laminating a layer containing an olefin polymer), a laminate obtained by stretching the layer and a stretched film containing a transparent resin are laminated so that their orientation directions are orthogonal to each other. An optical laminate is disclosed. Patent Document 4 discloses a transparent resin (such as a monocyclic olefin polymer) on at least one side of a layer containing a resin (such as a vinyl aromatic polymer) having a negative intrinsic birefringence value. A roll wound body of an optical laminate formed by uniaxially stretching a laminate formed by laminating a layer containing a roll wound body of a uniaxially stretched film containing a transparent resin in a specific direction The optical laminated body laminated | stacked by is disclosed. In Patent Documents 3 and 4, instead of the polymerizable liquid crystal layer in Patent Document 2, a resin layer having a negative intrinsic birefringence value is used.

However, in Patent Documents 3 and 4, the adhesion between a layer containing a resin having a negative intrinsic birefringence value and a layer containing a transparent resin is poor, and an adhesive layer is required between the layers. There is. As described above, a method for increasing the contrast ratio from the oblique direction and enabling uniform screen display has not been sufficiently established, and an improvement has been demanded.
JP-A-5-157911 JP 2007-206605 A Japanese Patent Laying-Open No. 2005-0777450 JP 2005-241965 A

  The present invention relates to a method for producing a laminated optical film, a laminated optical film having a high contrast ratio when a screen is viewed from an oblique direction in a liquid crystal display device, particularly an IPS mode liquid crystal display device, and a uniform screen display, and the same It is an object of the present invention to provide a polarizing plate and a liquid crystal display device using the same.

  As a result of intensive studies in view of the background as described above, the laminated optical film produced by a specific method has not been able to be achieved by the prior art, and has a predetermined phase difference when viewed from an oblique direction. It has been found that securing and securing the adhesion of each layer of the laminated film can be realized, and the present invention has been completed.

  That is, in the method for producing a laminated optical film of the present invention, the cyclic olefin resin (A) and the vinyl aromatic resin (B) are laminated and formed by a coextrusion method to obtain a coextruded film (α). The step (β) of stretching the coextruded film to obtain a laminated stretched film (C), and the laminated stretched film (C) are laminated on the transparent resin film (D) to obtain a laminated optical film (E). It is a manufacturing method of a laminated optical film which has a process (gamma), Comprising: This laminated optical film (E) satisfy | fills following formula (i) and Formula (ii), It is characterized by the above-mentioned.

70 (nm) ≦ R550 ≦ 350 (nm) (i)
(In the formula, R550 represents an in-plane retardation at a wavelength of 550 nm.)
0 <NZ <1 (ii)
(In the formula, NZ represents a coefficient represented by NZ = (nx−nz) / (nx−ny) at a wavelength of 550 nm. Here, nx represents an in-plane maximum refractive index, and ny represents: (In-plane represents the refractive index in the direction perpendicular to nx, and nz represents the refractive index in the thickness direction perpendicular to nx and ny.)
The cyclic olefin resin (A) is preferably composed of a copolymer having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2).

(In the formula, m represents an integer of 1 or more, p represents an integer of 0 or more, X is independently a group represented by the formula: —CH═CH—, or a formula: —CH ₂ CH _2- represents a group represented by-, and R ^{1 to} R ⁴ each independently represent a hydrogen atom; a halogen atom; a substituent optionally having a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. Or an unsubstituted hydrocarbon group having 1 to 30 carbon atoms; or a polar group, and R ¹ and R ² and / or R ³ and R ⁴ are integrated to form a divalent hydrocarbon group. R ¹ or R ² and R ³ or R ⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring, and the carbocyclic or heterocyclic ring may have a monocyclic structure or a polycyclic structure. it may be a ring structure. However, at least one group of R ¹ to R ^4, include atoms other than carbon atoms and hydrogen atoms.

(In the formula, Y is independently a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —, and R ^{5 to} R ⁸ are each independently A hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom; or a polar group , R ⁵ and R ⁶ , and / or R ⁷ and R ⁸ may be combined to form a divalent hydrocarbon group, and R ⁵ or R ⁶ and R ⁷ or R ⁸ are They may be bonded to each other to form a carbocycle or a heterocycle, and the carbocycle or heterocycle may be a monocyclic structure or a polycyclic structure.)
The vinyl aromatic resin (B) is preferably a styrene- (meth) acrylic acid copolymer or a styrene-maleic anhydride copolymer.

The cyclic olefin resin (A) and the vinyl aromatic resin (B) can be directly laminated to form a laminated film.
The glass transition temperature (TgA) of the cyclic olefin resin (A) and the glass transition temperature (TgB) of the vinyl aromatic resin (B) satisfy the relationship represented by the following formula (iii), and The stretching temperature in β) is preferably TgA or more and TgB or more.

−10 (° C.) ≦ TgB−TgA (iii)
The transparent resin film (D) is made of a cyclic olefin resin, and is preferably uniaxially stretched in the film width direction or the longitudinal direction.

The laminated stretched film (C) and the transparent resin film (D) are preferably laminated continuously by a roll-to-roll method.
The laminated optical film of the present invention is obtained by the above production method.

  Furthermore, the polarizing plate of the present invention is characterized in that the laminated optical film of the present invention is laminated on at least one surface of a polarizer via an adhesive or a pressure sensitive adhesive, and the liquid crystal display of the present invention. The apparatus has the polarizing plate of the present invention.

  According to the present invention, it is possible to provide a method for producing a laminated optical film and a laminated optical film that are excellent in production efficiency, ensure a predetermined retardation when viewed from an oblique direction, and are excellent in adhesion of each layer of the laminated film. it can. Further, according to the present invention, by using the laminated optical film of the present invention or the polarizing plate having the same, the luminance contrast ratio when the screen is viewed from an oblique direction in a liquid crystal display device, particularly an IPS mode liquid crystal display device. In addition, a liquid crystal display device that is high and can display a uniform screen can be provided.

  The method for producing a laminated optical film of the present invention comprises a step (α) of obtaining a coextruded film by laminating a cyclic olefin resin (A) and a vinyl aromatic resin (B) by a coextrusion method. A step (β) of obtaining a laminated stretched film (C) by stretching the coextruded film, and a step of obtaining the laminated optical film (E) by laminating the laminated stretched film (C) on the transparent resin film (D) ( A method for producing a laminated optical film having γ), wherein the laminated optical film (E) satisfies both of the characteristics represented by the following formulas (i) and (ii): .

70 (nm) ≦ R550 ≦ 350 (nm) (i)
(In the formula, R550 represents an in-plane retardation at a wavelength of 550 nm.)
0 <NZ <1 (ii)
(In the formula, NZ represents a coefficient represented by NZ = (nx−nz) / (nx−ny) at a wavelength of 550 nm. Here, nx represents an in-plane maximum refractive index, and ny represents: (In-plane represents the refractive index in the direction perpendicular to nx, and nz represents the refractive index in the thickness direction perpendicular to nx and ny.)
Hereinafter, the present invention will be specifically described.

≪Process (α) ≫
The step (α) is a step of obtaining a co-extruded film by laminating the cyclic olefin resin (A) and the vinyl aromatic resin (B) by a co-extrusion method. The layer made of the cyclic olefin resin (A) and the layer made of the vinyl aromatic resin (B) laminated in the coextruded film are also referred to as “A layer” and “B layer”, respectively.

<Cyclic olefin resin (A)>
As the cyclic olefin-based resin (A), any resin obtained by polymerizing or copolymerizing a cyclic olefin-based monomer that is a compound having a norbornene skeleton and hydrogenating as necessary can be used. Here, the polymerization or copolymerization of the cyclic olefin monomer may be addition polymerization or ring-opening polymerization.

  The cyclic olefin resin (A) is preferably a polymer or copolymer having at least one of structural units represented by the following formula (1) or the following formula (2) (hereinafter also referred to as “repeating unit”). More preferably, it is a copolymer having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2). Furthermore, it is optional to include other repeating units as necessary.

(In the formula (1), m represents an integer of 1 or more, p represents an integer of 0 or more, X is independently a group represented by the formula: —CH═CH—, or a formula: — Represents a group represented by CH ₂ CH ₂ —, R ¹
-R ⁴ each independently represents a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. A hydrogen group; or a polar group, and R ¹ and R ² and / or R ³ and R ⁴ may be combined to form a divalent hydrocarbon group, R ¹ or R ² , R ^{3 and} R ⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring, and the carbocyclic or heterocyclic ring may be a monocyclic structure or a polycyclic structure. However, at least one group of R ^{1 to} R ⁴ includes atoms other than carbon atoms and hydrogen atoms. )

(In formula (2), Y is independently a group represented by the formula: —CH═CH—, or a formula: —CH ₂ C
H ₂ - with a group represented, R ⁵ to R ⁸ are each independently a hydrogen atom, a halogen atom, an oxygen atom, a nitrogen atom, may have a linking group containing a sulfur atom or a silicon atom A substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; or a polar group, wherein R ⁵ and R ⁶ and / or R ⁷ and R ⁸ are combined to form a divalent hydrocarbon group. R ⁵ or R ⁶ and R ⁷ or R ⁸ may be bonded to each other to form a carbocyclic or heterocyclic ring, and the carbocyclic or heterocyclic ring may be a monocyclic structure A polycyclic structure may be used. )
The copolymer having the structural unit represented by the above formula (1) and the structural unit represented by the above formula (2) is composed of one or more monomers represented by the following formula (1m) (hereinafter “single” (Also referred to as “mer (1)”), one or more monomers represented by the following formula (2m) (hereinafter also referred to as “monomer (2)”), It is obtained by copolymerizing with a copolymerizable monomer.

(In formula (1m), the definitions of m, p, R ¹ , R ² , R ³ and R ⁴ are as defined in formula (1).)

(In formula (2m), definitions of R ⁵ , R ⁶ , R ⁷ and R ⁸ are as defined in formula (2).)
In the above formulas (1), (2), (1m) and (2m), R ^{1 to} R ⁸ have a linking group containing a hydrogen atom; a halogen atom; an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. Represents a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; or a polar group. These atoms and groups are described below.

Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.
Examples of the hydrocarbon group having 1 to 30 carbon atoms include alkyl groups such as methyl group, ethyl group and propyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group, allyl group and propenyl group. Groups and the like.

In addition, the substituted or unsubstituted hydrocarbon group may be directly bonded to the ring structure, or may be bonded via a linking group. Examples of the linking group include a divalent hydrocarbon group having 1 to 10 carbon atoms (for example, — (CH ₂ ) m — (wherein m is 1 to 1).
An alkylene group represented by an integer of 10); a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom (for example, a carbonyl group (—CO—), an oxycarbonyl group (—O (CO) —), Sulfone group (—SO ₂ —), ether bond (—O—), thioether bond (—
S-), imino group (—NH—), amide bond (—NHCO—, —CONH—), siloxane bond (—OSi (R ₂ ) — (wherein R is an alkyl group such as methyl or ethyl)), etc. A linking group containing a plurality of these may be used.

  Examples of the polar group include a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, an amide group, an imide ring-containing group, a triorganosiloxy group, a triorganosilyl group, and an amino group. Group, acyl group, alkoxysilyl group, sulfonyl-containing group, carboxyl group and the like. More specifically, examples of the alkoxy group include a methoxy group and an ethoxy group; examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group; and an aryloxycarbonyl group. Examples include a phenoxycarbonyl group, a naphthyloxycarbonyl group, a fluorenyloxycarbonyl group, a biphenylyloxycarbonyl group, and the like; examples of the triorganosiloxy group include a trimethylsiloxy group and a triethylsiloxy group; Examples of the triorganosilyl group include a trimethylsilyl group and a triethylsilyl group; examples of the amino group include a primary amino group, and examples of the alkoxysilyl group include a trimethoxysilyl group, Triethoxy Le group and the like; the acyl group include an acetyl group, a propionyl group, (meth) acryloyl group, benzoyl group, naphthoyl group and the like.

As a preferable aspect of cyclic olefin resin (A), the copolymer shown to following [1]-[3] can be mentioned. Of these, the copolymer shown in [3] is particularly preferred because of excellent thermal stability and excellent optical properties.

[1] A ring-opening copolymer of the monomer (1) and the monomer (2).
[2] A ring-opening copolymer of the monomer (1), the monomer (2), and other copolymerizable monomers.

[3] A hydrogenated product of the ring-opening copolymer of [1] and [2].
(Monomer (1))
The structural unit (1) is derived from the monomer (1). Specific examples of the monomer (1) are given below, but the present invention is not limited to these specific examples. Moreover, you may use a monomer (1) combining 2 or more types.

8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-phenoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8-methyl-8-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8-methyl-8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10
] -3-dodecene,
8-methyl-8-phenoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ]
-3-dodecene,
8-fluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-difluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-pentafluoroethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8-methyl-8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8,8,9-trifluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-tris (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9,9-tetrafluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-
Dodecene,
8,8,9,9-tetrakis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-difluoro-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluoro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-pentafluoropropoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoro-8-pentafluoroethyl-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluoro-8-heptafluoroiso-propyl-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-chloro-8,9,9-trifluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ]
-3-dodecene,
8,9-dichloro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene and the like.

Among these, it is preferable to use the monomer (1) having at least one polar group in the molecule. That is, in the above formula (1m), R ¹ and R ³ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ² and R ⁴ are a hydrogen atom or a monovalent organic group, ^{It is} preferable that at least one of ² and R ⁴ is a polar group other than a hydrogen atom and a hydrocarbon group, since adhesion and adhesion to other materials are improved.

  The content of the polar group in the copolymer is determined by a desired function and is not particularly limited. However, in order to improve adhesion and adhesion with other materials, all repeating units (1) The repeating unit (1) having a polar group therein is usually contained in an amount of 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more. All repeating units (1) may have a polar group. Due to the presence of the polar group, it is possible to improve the adhesion with the vinyl aromatic resin layer in the laminated film formation by coating.

Further, at least one of R ² and R ^{4 is} of the formula:
^{_{- (CH 2) n COOR 9}} ... (3)
(Here, n represents an integer of 0 to 5, preferably an integer of 0 to 2, more preferably 0. R ⁹ is a monovalent organic group.)
The monomer (1) which is a polar group represented by the formula is preferred in that the glass transition temperature and water absorption of the resulting copolymer can be easily controlled. As the monovalent organic group represented by R ⁹ in Formula (3),
For example, alkyl groups such as methyl group, ethyl group, propyl group; aryl groups such as phenyl group, naphthyl group, anthracenyl group, biphenylyl group; other aromatic rings such as fluorenes such as diphenylsulfone and tetrahydrofluorene, and furan And monovalent groups having a heterocyclic ring such as a ring or an imide ring.

  In the above formula (3), n is usually an integer of 0 to 5 as described above, but the smaller the value of n, the higher the glass transition temperature of the copolymer obtained, which is preferable. Monomer (1) in which is 0 is preferred in that its synthesis is easy.

  Furthermore, in the above formula (1m), the fact that an alkyl group is further bonded to the carbon atom to which the polar group represented by the above formula (3) is bonded is that the heat resistance and water absorption of the resulting copolymer are This is preferable for achieving balance. The alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 2, and particularly preferably 1.

In the formula (1m), the monomer (1) in which m is 1 and p is 0 is preferable in that a copolymer having a high glass transition temperature is obtained.
Specific examples of the monomer (1) include 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene increases the glass transition temperature of the resulting copolymer, is hardly affected by deformation due to water absorption, and has good adhesion and adhesion to other materials. It is preferable because water absorption can be maintained.

(Monomer (2))
The repeating unit (2) is derived from the monomer (2). Specific examples of the monomer (2) are given below, but the present invention is not limited to these specific examples. Moreover, you may use a monomer (2) combining 2 or more types.

Bicyclo [2.2.1] hept-2-ene,
5-methylbicyclo [2.2.1] hept-2-ene,
5-ethylbicyclo [2.2.1] hept-2-ene,
5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-methyl-5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-phenoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-methyl-5-phenoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-cyanobicyclo [2.2.1] hept-2-ene,
5-ethylidenebicyclo [2.2.1] hept-2-ene,
5-phenylbicyclo [2.2.1] hept-2-ene,
5- (2-naphthyl) bicyclo [2.2.1] hept-2-ene (both α and β types are acceptable),
5-fluorobicyclo [2.2.1] hept-2-ene,
5-fluoromethylbicyclo [2.2.1] hept-2-ene,
5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-pentafluoroethylbicyclo [2.2.1] hept-2-ene,
5,5-difluorobicyclo [2.2.1] hept-2-ene,
5,6-difluorobicyclo [2.2.1] hept-2-ene,
5,5-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5-methyl-5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5,5,6-trifluorobicyclo [2.2.1] hept-2-ene,
5,5,6-tris (fluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6,6-tetrafluorobicyclo [2.2.1] hept-2-ene,
5,5,6,6-tetrakis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5-difluoro-6,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-difluoro-5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-fluoro-5-pentafluoroethyl-6,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-difluoro-5-heptafluoro-iso-propyl-6-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-chloro-5,6,6-trifluorobicyclo [2.2.1] hept-2-ene,
5,6-dichloro-5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-6-trifluoromethoxybicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-6-heptafluoropropoxybicyclo [2.2.1] hept-2-ene,
5- (4-phenylphenyl) bicyclo [2.2.1] hept-2-ene,
4- (bicyclo [2.2.1] hept-5-en-2-yl) phenylsulfonylbenzene and the like can be mentioned.

Among these, the monomer (2) in which R ^{5 to} R ⁸ in the formula (2m) are all hydrogen atoms, or any one is a hydrocarbon group having 1 to 30 carbon atoms and the other is a hydrogen atom, The resulting optical film is preferable in that it has a large effect of improving the toughness, and in particular, R ^{5 to} R ⁸ are all hydrogen atoms, or any one is a methyl group, an ethyl group or a phenyl group, and the others are all hydrogen atoms. A certain monomer is preferable also from a heat resistant viewpoint. Furthermore, bicyclo [2.2.1] hept-2-ene and 5-phenylbicyclo [2.2.1] hept-2-ene are easy to synthesize, improve the toughness of the resin, and have a glass transition. This is preferable in that temperature adjustment and phase difference development can be improved.

  In the present invention, the content ratio of the structural unit (1) and the structural unit (2) in the cyclic olefin resin (A) preferably used is usually (1) :( 2) = 95: 5-5: 95, preferably 95: 5 to 60:40, more preferably 95: 5 to 70:30, and still more preferably 95: 5 to 75:25. If the proportion of the structural unit (1) is larger than the above range, the effect of improving toughness may not be expected. On the contrary, if the proportion of the structural unit (1) is smaller than the above range, the glass transition temperature is lowered and the heat resistance is improved. Problems may arise.

  Moreover, in order to improve adhesiveness and adhesiveness with other materials, the repeating unit having a polar group in the total amount of the structural unit (1) and the structural unit (2) is usually 50 to 95 mol%, preferably 70 to It is contained in an amount of 95 mol%, more preferably 80 to 95 mol%. The presence of the polar group can improve the adhesion with the vinyl aromatic resin layer in the laminated film formation by coextrusion.

(Other copolymerizable monomers)
Examples of the other copolymerizable monomer that can be copolymerized with the monomer (1) and the monomer (2) include, for example, cyclobutene, cyclopentene, cycloheptene, cyclooctene, and tricyclo [5.2.1. And cycloolefins such as 0 ^2,6 ] -3-decene and dicyclopentadiene. The number of carbon atoms in the cycloolefin is preferably 4-20, and more preferably 5-12. These copolymerizable monomers are useful for modifying the resin, such as improving retardation development, adjusting Tg, and improving coating properties.

  Furthermore, in the presence of an unsaturated hydrocarbon polymer having an olefinically unsaturated bond in the main chain such as polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-nonconjugated diene copolymer, polynorbornene, etc. The body (1) and the monomer (2) may be polymerized. The copolymer obtained in this case is useful as a raw material for resins having high impact resistance.

  The use ratio of the monomers (1) and (2) to the copolymerizable cyclic monomer or unsaturated double bond-containing compound is as follows: monomer (1) + (2): copolymerizable cyclic monomer Or it is preferable that an unsaturated double bond containing compound is 100: 0-50: 50 by weight ratio, More preferably, it is 100: 0-60: 40, More preferably, it is 100: 0-70: 30.

(Ring-opening polymerization catalyst)
The ring-opening polymerization reaction of the specific monomer is preferably performed in the presence of a metathesis catalyst. The metathesis catalyst includes at least one metal compound selected from a tungsten compound, a molybdenum compound, and a rhenium compound (hereinafter referred to as “component (a)”) and a Group 1 element of the periodic table (for example, Li, Na, K). Etc.), Group 2 elements (eg Mg, Ca etc.), Group 12 elements (eg Zn, Cd, Hg etc.), Group 13 elements (eg B, Al etc.), Group 4 elements (eg , Ti, Zr, etc.) or a group 14 element (for example, Si, Sn, Pb, etc.) compound, and at least one selected from those having at least one of the element-carbon bond or the element-hydrogen bond It consists of a combination with a seed compound (hereinafter referred to as “component (b)”), and may contain an additive (hereinafter referred to as “component (c)”) in order to enhance the catalytic activity.

Specific examples of suitable metal compounds constituting the component (a) include metal compounds described in JP-A-1-240517 such as WCl ₆ , MoCl ₅ , and ReOCl ₃ .

Specific examples of the compound constituting the component (b) include n-C ₄ H ₉ Li, (C ₂ H ₅ ) ₃ A
l, (C ₂ H ₅ ) ₂ AlCl, (C ₂ H ₅ ) _1.5 AlCl _1.5 , (C ₂ H ₅ ) AlCl ₂ , methylaluminoxane, LiH, etc., the compounds described in JP-A-1-240517 Can do.

  As the component (c), alcohols, aldehydes, ketones, amines and the like are suitable, but in addition, compounds disclosed in JP-A-1-240517 can be used.

In addition, as a metathesis catalyst other than the components (a) to (c), a known ruthenium compound can be used as a Grubbs catalyst.
(Hydrogenation)
The hydrogenation rate in the hydrogenated (co) polymer shown in the above [3] is usually 50% or more, preferably 70% or more, more preferably 90% or more, further preferably 97% or more, particularly preferably 99% or more. It is.

The cyclic olefin resin (A) has a logarithmic viscosity (η _inh ) measured in chloroform at 30 ° C.
) Is preferably 0.2 to 5.0 dL / g.
Moreover, the number average molecular weight (Mn) of polystyrene conversion measured by gel permeation chromatography (GPC) is 8,000-10 as for the average molecular weight of cyclic olefin resin.
Those having a weight average molecular weight (Mw) of 20,000 to 300,000 are preferred.

  Furthermore, the glass transition temperature (TgA) of the cyclic olefin-based resin (A) is preferably 100 to 250 ° C, more preferably 110 to 180 ° C, and still more preferably 120 to 170, in order to ensure thermal stability and stretch processability. ° C. Moreover, the cyclic olefin resin (A) layer may be formed from a resin composition containing the cyclic olefin resin as described above. In addition to the cyclic olefin resin, the resin composition includes an antioxidant, a heat stabilizer, a light stabilizer, a phase difference adjusting agent, an ultraviolet absorber, an antistatic agent, a dispersant, and a processability improver as necessary. , Chlorine scavengers, flame retardants, crystallization nucleating agents, antiblocking agents, antifogging agents, mold release agents, pigments, organic or inorganic fillers, neutralizing agents, lubricants, decomposition agents, metal deactivators, contamination Known additives such as an inhibitor, an antibacterial agent, other resins, and a thermoplastic elastomer can be added as long as the effects of the invention are not impaired.

<Vinyl aromatic resin (B)>
The vinyl aromatic resin (B) preferably has a structural unit represented by the following formula (4) (hereinafter also referred to as “structural unit (4)”).

(In formula (4), R ¹⁰ represents a hydrogen atom or a methyl group. R ^{11 to} R ¹³ each independently represent a hydrogen atom; a halogen atom; a linkage containing an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom. A substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a group; or a polar group.)
Specific examples of the monomer for deriving the structural unit (4) include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, p-trifluoromethylstyrene, p-methoxystyrene, and p-hydroxystyrene. , P-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, p-tertbutoxystyrene, 2,4,6-trimethylstyrene, p-isopropenylphenol and the like. . Any of these monomers may be used alone or in combination of two or more. Of these monomers, styrene, α-methylstyrene, p-hydroxystyrene, and p-isopropenylphenol are preferably used alone or in combination.

Furthermore, the vinyl aromatic resin (B) is particularly excellent in adhesion to the cyclic olefin resin (A), has a high glass transition temperature, and easily expresses the desired optical properties. ) And a structural unit represented by the following formula (5) (hereinafter also referred to as “structural unit (5)”) and / or a structural unit represented by the following formula (6) (hereinafter “structural unit (6)”). It is also preferable to have a. When the structural unit (5) is included, the resulting laminated optical film has excellent surface smoothness. When the structural unit (6) is included, there is an advantage that the resin is hardly deteriorated by heat during processing.

(In formula (5), X represents an oxygen atom or a nitrogen atom having a substituent. In formula (6), R ¹⁴ represents a hydrogen atom or a methyl group, and R ¹⁵ represents a hydrogen atom or the number of carbon atoms. Represents a hydrocarbon group having 1 to 30. Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group such as a methyl group, an ethyl group, and a propyl group, a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, and vinyl. And alkenyl groups such as an allyl group, a propenyl group, and the like.)
The vinyl aromatic resin (B) may have a structure including both the structural unit (5) and the structural unit (6), and the structural unit (5) and the structural unit (6). ) May be included. Moreover, the acid anhydride structure or imide structure of the repeating unit (5) may be hydrolyzed into a dicarboxylic acid structure or an amic acid structure.

  Specific examples of the monomer for deriving the structural unit (5) include N-substituted maleimides such as maleic anhydride, maleimide and N-phenylmaleimide; maleic acid and derivatives thereof; fumaric acid and derivatives thereof. Any of these monomers may be used alone or in combination of two or more. Among these monomers, maleic anhydride and N-phenylmaleimide are preferably used in terms of heat resistance and adhesion to the cyclic olefin resin (A).

  Specific examples of the monomer that derives the structural unit (6) include (meth) acrylic acid, (meth) acrylic acid alkyl esters such as methyl (meth) acrylate; (meth) acrylic amide, and the like. Any of these monomers may be used alone or in combination of two or more. Of these monomers, (meth) acrylic acid and methyl (meth) acrylate are preferably used in terms of heat resistance and adhesion to the cyclic olefin resin (A).

From the above, styrene- (meth) acrylic acid copolymer and styrene-maleic anhydride copolymer are particularly preferable as the vinyl aromatic resin (B).
In the present invention, the ratio of the structural unit (4) in the vinyl aromatic resin (B) to the structural unit (5) and / or the structural unit (6) is usually (4) :( (5) + (6)) = 100: 0 to 50:50, preferably 98: 2 to 60:40, more preferably 95: 5 to 70:30. When the use ratio is in the above range, it is possible to adjust the glass transition temperature, adjust the retardation, secure the stretch processability, and secure the adhesion to the cyclic olefin resin layer.

In addition to the structural units (5) and (6), the vinyl aromatic resin (B) includes ethylene, propylene, butene, butadiene, isoprene, (meth) acrylonitrile, α-
Other monomers such as chloroacrylonitrile, vinyl acetate, vinyl chloride, and itaconic anhydride may also be included as a copolymerization component.

The vinyl aromatic resin (B) preferably has a logarithmic viscosity (η _inh ) measured in a 30 ° C. chlorobenzene solution (concentration 0.5 g / dL) of 0.1 to 3.0 dL / g. Further, the polystyrene-equivalent weight average molecular weight Mw measured by gel permeation chromatography (GPC) is usually 30,000 to 1,000,000, preferably 40,000 to 800,000, more preferably 50,000 to 500,000. If the molecular weight is too small, the strength of a molded product such as a film obtained may be lowered. If the molecular weight is too large, the melt viscosity becomes too high, and the productivity and workability of the resin composition used in the present invention may deteriorate.

Moreover, the molecular weight distribution (Mw / Mn) of the vinyl aromatic resin (B) is usually 1.0 to 10, preferably 1.2 to 5.0, more preferably 1.2 to 4.0.
In the vinyl aromatic resin (B), the above monomer for deriving the structural unit (4), if necessary, the structural unit (5) and / or the structural unit (6), is present in the presence of a suitable polymerization initiator. It is preferable to manufacture by the method of carrying out a polymerization reaction under. As the polymerization initiator, it is preferable to use a radical polymerization initiator, an anionic polymerization catalyst, a coordination polymerization catalyst, a cationic polymerization catalyst, or the like, and it is particularly preferable to use a radical polymerization initiator.

  As the radical initiator used in the polymerization reaction, a known organic peroxide that generates free radicals or an azobis-based radical polymerization initiator can be used. Note that a polyfunctional initiator or an initiator that easily causes a hydrogen abstraction reaction is not preferable because the linearity of the resulting styrene copolymer may be lowered.

Organic peroxides include diacetyl peroxide, dibenzoyl peroxide, diisobutyroyl peroxide, di (2,4-dichlorobenzoyl) peroxide, di (3,5,5-trimethylhexanoyl) peroxide, di Diacyl peroxides such as octanoyl peroxide, dilauroyl peroxide, distearoyl peroxide, bis {4- (m-toluoyl) benzoyl} peroxide;
Ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, acetylacetone peroxide;
Hydrogen peroxide, t-butyl hydroperoxide, α-cumene hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, t-hexyl hydro Hydroperoxides such as peroxides;
Di-t-butyl peroxide, dicumyl peroxide, dilauryl peroxide, α, α′-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-bis (t-butylperoxide Dialkyl peroxides such as oxy) hexane, t-butylcumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3;
t-butyl peroxyacetate, t-butyl peroxypivalate, t-hexyl peroxypivalate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, 2,5-dimethyl-2 , 5-bis (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy 2-ethylhexanoate, t-hexylperoxy 2-ethylhexanoate, t-butylperoxy 2 -Ethylhexanoate, t-butyl peroxyisobutyrate, t-butyl peroxymaleate,
t-butylperoxy 3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-bis (m-toluoylperoxy) hexane, α, α'- Bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecano Ate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxybenzoate, t-hexylperoxybenzoate, bis (t-butylperoxy) isophthalate, 2,5 -Dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxymethyl Oil benzoate, 3,3 ', peroxy esters such as 4,4'-tetra (t-butyl peroxy carbonyl) benzophenone;
1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) 3,3 , 5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, 2,2-bis (t-butylperoxy) butane, n -Peroxyketals such as butyl 4,4-bis (t-butylperoxy) pivalate and 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane;
Peroxymonocarbonates such as t-hexylperoxyisopropyl monocarbonate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-butylperoxyallyl monocarbonate;
Di-sec-butyl peroxydicarbonate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate Peroxydicarbonates such as di-2-ethylhexyl peroxydicarbonate, di-2-methoxybutyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate;
In addition, although t-butyl trimethylsilyl peroxide etc. are mentioned, the organic peroxide used for this invention is not limited to these exemplary compounds.

Examples of the azobis radical polymerization initiator include azobisisobutyronitrile, azobisisovaleronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), and 2,2′-azobis. (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2- (carbamoylazo) isobutyronitrile 2,2′-azobis [2-methyl-N- {1,1-bis (hydroxymethyl) -2-hydroxyethyl} propionamide], 2,2′-azobis [2-methyl-N- {2- (1-hydroxybutyl)} propionamide], 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2′-azobis N- (2-propenyl) -2-methylpropionamide], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis (N-cyclohexyl-2-methylpropionamide) 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] di Hydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2′-azobis [2- (3,4,5,6-tetrahydropyrimidine-2 -Yl) propane] dihydrochloride, 2,2'-azobis [2- {1-
(2-hydroxyethyl) -2-imidazolin-2-yl} propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis (2 -Methylpropionamidine) dihydrochloride, 2,2'-azobis [N- (2-carboxyethyl) -2-methyl-propionamidine], 2,2'-azobis (2-methylpropionamidoxime), dimethyl 2, 2′-azobisbutyrate,
4,4′-azobis (4-cyanopentanoic acid), 2,2′-azobis (2,4,4-trimethylpentane) and the like, and the azobis radical polymerization initiator used in the present invention is It is not limited to these exemplary compounds.

  These radical initiators are used in an amount of generally 0.01 to 5 mol%, preferably 0.03 to 3 mol%, more preferably 0.03 mol%, based on 100 mol% of the total amount of monomers for inducing the vinyl aromatic resin (B). It is 05-2 mol%.

  Furthermore, a catalyst may be used in the polymerization reaction of the monomer for inducing the vinyl aromatic resin. This catalyst is not specifically limited, For example, a well-known anion polymerization catalyst, a coordination polymerization catalyst, a cationic polymerization catalyst etc. are mentioned.

  The polymerization reaction of the monomer for inducing the vinyl aromatic resin is carried out in the presence of the polymerization initiator or catalyst in the form of bulk polymerization, solution polymerization, precipitation polymerization, emulsion polymerization, suspension polymerization or bulk. -It is carried out by copolymerization by a conventionally known method such as a suspension polymerization method.

  The solvent used when performing the solution polymerization is not particularly limited as long as it dissolves the monomer and the polymer, but a hydrocarbon solvent such as cyclohexane, an aromatic hydrocarbon solvent such as toluene, Ketone solvents such as methyl ethyl ketone are preferred. The amount of the solvent used is preferably 0 to 3 times (weight ratio) based on the total amount of the monomers.

  The polymerization reaction time is usually 1 to 30 hours, preferably 3 to 20 hours, and the polymerization reaction temperature is not particularly limited because it depends on the type of radical initiator used, but usually 40 to 180 ° C., preferably 50-120 ° C.

  The glass transition temperature (TgB) of the vinyl aromatic resin (B) is preferably 110 to 200 ° C, more preferably 120 to 170 ° C in order to ensure thermal stability and stretch processability. In the present invention, it is preferable that the glass transition temperature (TgA) and TgB of the cyclic olefin resin (A) satisfy the relationship represented by the following formula (iii).

−10 (° C.) ≦ TgB−TgA (iii)
That is, the difference (TgB-TgA) between the glass transition temperature (TgA) of the cyclic olefin resin (A) and the glass transition temperature (TgB) of the vinyl aromatic resin (B) is preferably −10 ° C. or more. More preferably, it is −5 ° C. or higher, more preferably 0 ° C. or higher, that is, TgB ≧ TgA. By setting the glass transition temperature in the above range, the phase differences of the cyclic olefin resin (A) and the vinyl aromatic resin (B) can be simultaneously controlled by the step (β). It is possible to easily obtain the characteristics (characteristics represented by the above formula (i) and the above formula (ii)).

  In the present invention, the vinyl aromatic resin (B) may be formed from a resin composition containing the vinyl aromatic resin as described above. In addition to vinyl aromatic resins, resin compositions include antioxidants, heat stabilizers, light stabilizers, phase difference regulators, UV absorbers, antistatic agents, dispersants, and processability as needed. Agent, chlorine scavenger, flame retardant, crystallization nucleating agent, antiblocking agent, antifogging agent, mold release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, Known additives such as antifouling materials, antibacterial agents, other resins, and thermoplastic elastomers can be added as long as the effects of the invention are not impaired.

  Also, commercially available resins such as NOVA Chemicals' Dilark D332, Dairaku D232, Dainippon Ink & Chemicals's Lurex A14, Lurex A15, and CHI MEI's PN-177 can be preferably used as the vinyl aromatic resin of the present invention. .

<Co-extrusion method>
In the step (α), the coextrusion method in which the cyclic olefin resin (A) and the vinyl aromatic resin (B) are simultaneously formed and laminated may be, for example, a coextrusion T-die method, a coextrusion inflation method, Examples include an extrusion lamination method. Of these, the co-extrusion T-die method is preferable because a co-extruded film having a small thickness variation and a uniform thickness ratio between the A layer and the B layer can be obtained. In the present invention, a co-extruded film consisting of two layers of A layer / B layer, a co-extruded film consisting of three layers of A layer / B layer / A layer, and a co-extruded film consisting of three layers of B layer / A layer / B layer. An extruded film is suitably used from the viewpoint of production efficiency, ensuring strength, optical properties, and phase difference control. A laminated optical film composed of two layers is more preferable in terms of optical properties (transparency) and retardation control, and a laminated optical film composed of three layers is more preferable for preventing warping of the film and obtaining mechanical strength.

  The extrusion temperature in the co-extrusion method is appropriately selected so that the resin has a melt viscosity suitable for extrusion film formation, but is preferably 200 to 350 ° C, more preferably 230 to 300 ° C, and further preferably 240 to 280 ° C. is there. In addition, the temperature difference between the extrusion temperature of the cyclic olefin resin (A) and the extrusion temperature of the vinyl aromatic resin (B) is melted by the temperature change when both resins contact in the T-die or feed block. The viscosity is preferably within 50 ° C, more preferably within 30 ° C, and even more preferably within 20 ° C so that the viscosity does not change excessively and the moldability does not deteriorate. The difference in melt viscosity between the cyclic olefin resin (A) and the vinyl aromatic resin (B) is preferably within 5 times, more preferably 3 in order to ensure the moldability, particularly the uniformity of the thickness of each layer. Within 2 times, more preferably within 2 times.

  Since the A layer made of the cyclic olefin resin (A) and the B layer made of the vinyl aromatic resin (B) are excellent in mutual adhesion, an adhesive layer or an adhesive layer is provided between the layers, or corona treatment In addition, since it is not necessary to perform easy adhesion treatment such as plasma treatment or primer treatment, it is preferable to form a laminated film in direct contact. Sufficient adhesion strength can be obtained in a state where the A layer and the B layer are in direct contact by heat fusion by coextrusion. Further, even after the stretching treatment, the adhesion between the A layer and the B layer is maintained well.

  Thus, it is desirable that the coextruded film laminated and formed by the coextrusion method has a uniform thickness in each layer in both the width direction and the length direction. The thickness variation causes a phase difference variation of the obtained laminated optical film, and impairs the uniformity of display when it is incorporated in a liquid crystal display device. Accordingly, there are few die lines (longitudinal streaks due to scratches on the T-die lip), cross marks (periodic thickness fluctuations in the length direction), etc. that cause variations in the thickness of each layer. desirable. Further, it is desirable that there are few gels, foreign matters, etc. that cause display defects such as bright spots and light leakage as point-like defects. These include, for example, use of an extruder having a polymer filter, optimization of the residence time of the molten resin, reduction of pulsation of the gear pump, polishing and surface treatment of the T-die lip, smoothing of the transfer roll and peeling roll, roll surface treatment, etc. Can be suppressed. The thickness distribution of each layer in the co-extruded film formed by lamination is preferably within ± 10%, more preferably within ± 5%, and particularly preferably within ± 2%. In order to reduce the retardation variation of the laminated optical film, it is desirable that the variation in the thickness ratio between the A layer and the B layer of the coextruded film is small, and the average thickness ratio is within ± 10%, more preferably ± 5. %, Particularly preferably within ± 2%.

≪Process (β) ≫
Step (β) is a step in which the coextruded film produced in step (α) is stretched to obtain a laminated stretched film (C).

<Laminated stretched film (C)>
The laminated stretched film (C) is obtained by stretching the coextruded film produced by the step (α). As the stretching method, conventionally known methods can be applied, but longitudinal uniaxial stretching that extends in the film longitudinal direction, transverse uniaxial stretching that extends in the direction perpendicular to the film longitudinal direction, that is, the width direction, and lateral uniaxial stretching after longitudinal uniaxial stretching. Sequential biaxial stretching is preferred. Specifically, the longitudinal uniaxial stretching is preferably a method of uniaxial stretching using a difference in peripheral speed of the roll, and the lateral uniaxial stretching is preferably a method of uniaxial stretching using a tenter.

  The stretching temperature is usually determined based on the TgA of the cyclic olefin resin (A) and the TgB of the vinyl aromatic resin (B) in any stretching method, but it should be TgA or more and TgB or more. It is preferable for adjusting the phase difference. More preferably, it is a range satisfying both TgA to TgA + 50 ° C. and TgB to TgB + 50 ° C., more preferably a range satisfying both TgA to TgA + 30 ° C. and TgB to TgB + 30 ° C.

  By setting the stretching temperature in the above range, the retardation of each of the cyclic olefin resin (A) and the vinyl aromatic resin (B) can be controlled simultaneously by stretching, and the desired characteristics of the laminated optical film (above Formula (i) and the characteristics represented by the above formula (ii)) can be easily obtained. Thereby, a liquid crystal display device having a high contrast ratio when the screen is viewed from an oblique direction can be realized.

  The stretching ratio is usually 1.1 to 10 times, preferably 1.2 to 7 times, more preferably 1.3 to 5 times for both longitudinal uniaxial stretching and transverse uniaxial stretching. In sequential biaxial stretching, it is preferable to set the stretching temperature / stretching ratio of longitudinal uniaxial stretching and the stretching temperature / stretching ratio of lateral uniaxial stretching within the above ranges, respectively. By setting the draw ratio in the above range, the optical axis, retardation value, NZ coefficient, and distribution in the film plane of the retardation film can be suitably controlled.

  The laminated stretched film (C) obtained by each of the above stretching methods has the optical properties of the transparent resin film (D) and the laminated optical film (E) after the step (γ). It is possible to bond the laminated optical film (E) and the polarizer by a roll-to-roll method, thereby improving productivity.

≪Process (γ) ≫
Step (γ) is a step in which the laminated stretched film (C) is laminated on the transparent resin film (D) to obtain a laminated optical film (E).

The laminated stretched film (C) and the transparent resin film (D) are preferably laminated continuously by a roll-to-roll method.
In the roll-to-roll method, the rolls of the laminated stretched film (C) and the roll of the transparent resin film (D) are unwound on the same line and transported, and the two films are bonded together and wound up again on the roll. Say the method. In the conventional method, a method of punching a film into a shape of a liquid crystal display device, for example, a rectangle, and bonding the punched individual sheet films to each other or a polarizer is used, which is troublesome and poor in productivity. When the roll-to-roll method is used, the film is bonded by continuously flowing between apparatuses, and has an advantage of greatly increasing productivity.

<Transparent resin film (D)>
The transparent resin film (D) is preferably made of a cyclic olefin resin, and is desirably uniaxially stretched in the film width direction or longitudinal direction.

  The cyclic olefin-based resin is excellent in transparency, heat resistance, dimensional stability, low photoelasticity, and the like, and has excellent toughness, retardation control, and adhesion to other materials. ) Is preferred.

The specific method of uniaxial stretching can use the same method as the stretching in the step (β).
<Laminated optical film (E)>
The laminated optical film (E) is obtained by laminating the laminated stretched film (C) on the transparent resin film (D) in the step (γ).

Moreover, the laminated optical film of the present invention is obtained by the production method having the steps (α) to (γ).
The length in the longitudinal direction of the laminated optical film (E) is preferably 50 m or more, and more preferably 100 m or more. Such a long film is usually handled as a film roll. The width of the film is preferably 1,000 mm or more, more preferably 1,500 mm or more, and particularly preferably 2,000 mm or more.

  The thickness of the laminated optical film (E) is not particularly limited, but the film thickness is usually 10 to 400 μm, preferably 20 to 300 μm, particularly preferably 20 to 200 μm. This is desirable for adjusting the phase difference value.

  Further, it is desirable that the thickness variation is small since the variation of the phase difference value is small and the display quality is uniform. The range of thickness variation of the laminated optical film (E) is within an average value ± 10%, preferably within an average value ± 5%, and more preferably within an average value ± 2%.

(Optical characteristics of laminated optical film)
The laminated optical film satisfies the following formulas (i) and (ii).
70 (nm) ≦ R550 ≦ 350 (nm) (i)
(In the formula, R550 represents an in-plane retardation at a wavelength of 550 nm.)
0 <NZ <1 (ii)
(In the formula, NZ represents a coefficient represented by NZ = (nx−nz) / (nx−ny) at a wavelength of 550 nm. Here, nx represents an in-plane maximum refractive index, and ny represents: In the plane, the refractive index is in the direction perpendicular to nx, and nz is the refractive index in the thickness direction perpendicular to nx and ny, where Nave = It is represented by (nx + ny + nz) / 3, and Nave is a value obtained by weighted average of the average refractive indexes of the cyclic olefin resin (A) and the vinyl aromatic resin (B) in the laminated optical film by the thickness ratio. is there.)
The above formula (i) indicates the amount of retardation in the film plane. As a retardation film for an IPS mode liquid crystal display device, a compensation method combining an A plate and a positive C plate is known to be effective, and in this case, an in-plane retardation R550 that effectively functions as an A plate. Is the range shown in Formula (i), preferably 70 to 250 nm, more preferably 80 to 200 nm. Satisfying the formula (i) contributes to further improvement of the contrast ratio when observed from an oblique direction.

Further, the range of variation of R550 in formula (i) is preferably within ± 7 nm, more preferably within ± 5 nm, and particularly preferably within ± 3 nm.
Similarly, in order to obtain display quality uniformity, it is desirable that there is less variation in the optical axis depending on the location, and based on the direction in which the slow axis is present in the film longitudinal direction or the film width direction perpendicular to the film longitudinal direction, It is preferably within ± 2 °, more preferably within ± 1 °, even more preferably within ± 0.7 °, and particularly preferably within ± 0.5 °.

The above formula (ii) is a numerical value called an NZ coefficient, and is a numerical value representing the balance between the in-plane retardation of the laminated optical film and the thickness direction retardation. In order to calculate the NZ coefficient, the in-plane retardation and the oblique direction retardation of the laminated optical film (usually the value when entering from a polar angle of 40 ° with a slow axis inclination) are measured, and the total film thickness and film By calculating numerically using the average refractive index, nx, ny, and nz are obtained and determined as NZ = (nx−nz) / (nx−ny) therefrom. However, in the case of the laminated optical film of the present invention, since the average refractive index of the cyclic olefin resin (A) and the vinyl aromatic resin (B) is different, Nave cannot be measured directly.

  Therefore, for convenience, the average refractive index Nave of the laminated optical film is a value obtained by weighted averaging of the average refractive indexes of the A layer and the B layer by the thickness ratio. That is, when the average refractive index of the A layer is NaveA, the thickness is dA (μm), the average refractive index of the B layer is NaveB, and the thickness is dB (μm), Nave = (dA × NaveA + dB × NaveB) / ( nx, ny, and nz are numerically calculated as dA + dB) to determine NZ.

  The thickness dA, dB of each layer is determined by peeling each layer and measuring the thickness of each layer with a contact micrometer, or observing the cross section of the laminated optical film with a microscope, or a known non-contact measurement method, for example, It is measured using an optical interference type film thickness measuring device. Among them, the optical interference type film thickness measurement is preferable because the measurement accuracy is good, it is nondestructive, and it can be measured both online and offline.

  The NZ coefficient has a smaller change in the phase difference value regardless of the direction closer to 0.5, which matches the compensation method combining the A plate and the positive C plate, which are compensation methods for IPS liquid crystal, and contrast. This is desirable because the ratio is improved. Preferably it is 0.1-0.9, More preferably, it is 0.2-0.8.

  The thickness ratio between the A layer and the B layer is not particularly limited as long as the optical characteristics of each layer and the entire laminated optical film are within a desired range, but in order to control the phase difference, specifically, a single stretching process. In order to develop a predetermined retardation, the thickness ratio of the A layer is preferably 10 to 90%, more preferably 20 to 80%, and still more preferably 20 to 70% of the entire laminated optical film. In order to obtain display quality uniformity, it is desirable that the thickness ratio between the A layer and the B layer of the laminated optical film (E) is small, and the average thickness ratio is within ± 10%, more preferably within ± 5%. Particularly preferably, it is within ± 2%. When there are two or more A layers and / or B layers, the thicknesses of the respective layers are summed and expressed as a thickness ratio of all the A layers to the entire laminated optical film.

  Similarly, in order to obtain display quality uniformity, it is desirable that there is less variation in NZ due to location. The variation range of NZ is within an average value ± 0.3, preferably within an average value ± 0.2, and more preferably within an average value ± 0.1.

  In order for the NZ coefficient to satisfy the above formula (i), there is a desirable range of NZ coefficients for the A layer and the B layer constituting the laminated optical film. However, since the NZ coefficient of each of the A layer and the B layer cannot be obtained in the laminated state, the A layer and the B layer are peeled off from the laminated optical film, and the phase difference is measured separately to obtain the NZ coefficient. A film consisting only of the resin (A) and a film consisting only of the vinyl aromatic resin (B) are stretched under the same conditions as the laminated optical film, and the phase difference is measured separately to obtain the approximate NZ coefficient of each layer. This method is used. When the NZ coefficient of the cyclic olefin resin (A) is NZA and the NZ coefficient of the vinyl aromatic resin (B) is NZB, the following conditions (iv) to (v) are satisfied.

1.0 ≦ NZA ≦ 5.0 (iv)
NZB ≦ 0 (v)
(In the above formula (iv), NZA is a coefficient represented by NZA = (nxA-nzA) / (nxA-nyA) and is a value at a wavelength of 550 nm. Here, nxA is a cyclic olefin resin ( The maximum refractive index in the plane of A), nyA is the refractive index in the direction orthogonal to nxA in the plane of the cyclic olefin resin (A), and nzA is the cyclic olefin resin orthogonal to nxA and nyA ( A) represents the refractive index in the thickness direction, and NaveA = (nxA + nyA + nzA) / 3.

In the above formula (v), NZB is a coefficient represented by NZB = (nxB−nzB) / (nxB−nyB), and is a value at a wavelength of 550 nm. Here, nxB is the maximum refractive index in the plane of the vinyl aromatic resin (B), nyB is the refractive index in the direction perpendicular to nyB in the plane of the vinyl aromatic resin (B), and nzB is The refractive index in the thickness direction of the vinyl aromatic resin (B) orthogonal to nxB and nyB is represented, and NaveB = (nxB + nyB + nzB) / 3. )
The above formula (iv) corresponds to the phase difference developed when the cyclic olefin-based resin layer is horizontally stretched, nxA is the stretching direction (in the case of sequential biaxial stretching, the direction of lateral uniaxial stretching), and nyA Is perpendicular to the stretching direction (in the case of sequential biaxial stretching, the film longitudinal direction is perpendicular to the direction of transverse uniaxial stretching). In the refractive index ellipsoid, nxA> nyA ≧ nzA. The above formula (v) corresponds to the phase difference that is manifested when the B layer is stretched transversely, and nxB is orthogonal to the stretching direction (in the case of sequential biaxial stretching, the film longitudinal direction that is orthogonal to the direction of lateral uniaxial stretching) NyB is the stretching direction (in the case of sequential biaxial stretching, the direction of transverse uniaxial stretching). In the refractive index ellipsoid, nzB ≧ nxB> nyB. The NZ of the laminated optical film cannot be determined by simple calculation from NZA and NZB. The change in the polarization state of the cyclic olefin resin (A) and the polarization state of the vinyl aromatic resin (B) by Poincare sphere display Associated as a result of changes.

  Further, in order to obtain display quality uniformity, it is desirable that both NZA and NZB have less variation due to location. The variation ranges of NZA and NZB are each preferably within an average value ± 0.2, and more preferably within an average value ± 0.1.

<Polarizing plate>
The polarizing plate of the present invention is characterized in that the laminated optical film of the present invention is laminated on at least one surface of a polarizer (polarizing film) via an adhesive or a pressure-sensitive adhesive.

  As a polarizer, for example, a film made of polyvinyl alcohol (PVA) or a polymer obtained by formalizing a part of PVA, a dyeing treatment with a dichroic substance made of iodine or a dichroic dye, a stretching treatment, and a crosslinking treatment. The film is obtained by applying an appropriate order and method, and is transmitted as linearly polarized light when natural light is incident thereon. In particular, a material having a high light transmittance and an excellent degree of polarization is suitable.

  The thickness of the polarizer is generally preferably 5 to 80 μm, but the present invention is not limited to this. In addition to the PVA-based film, other polarizers can be used as long as they exhibit similar characteristics. For example, a film made of a cyclic olefin resin may be subjected to dyeing treatment, stretching treatment, crosslinking treatment, etc. in an appropriate order or method, or a dichroic dye or the like may be applied and oriented on a base film. Alternatively, a coating type polarizer or a wire grid type polarizer may be used.

Usually, a polarizing plate is composed of a polarizer, a retardation film, and a protective film. However, in the present invention, as a retardation film that constitutes a polarizing plate, a laminated optical film is attached to at least one surface of the polarizer with an adhesive or an adhesive. It is used by pasting it through an agent. The laminated optical film may be bonded to the polarizer on the cyclic olefin resin (A) side, or may be bonded to the polarizer on the vinyl aromatic resin (B) side, and a transparent resin film ( It may be bonded with a polarizer on the D) side. The surface to be bonded to the polarizer is appropriately selected depending on the layer configuration of the laminated optical film (E), stretching conditions, and the like. In such a polarizing plate, the retardation film is excellent in properties such as heat resistance, moisture resistance, chemical resistance and the like, and has a sufficient function as a protective film. A protective film may not be separately laminated on the surface on which the laminated optical film of the invention is laminated. When the polarizing plate of the present invention has a configuration in which the laminated optical film of the present invention having a function as a retardation film is laminated only on one side of the polarizer, the other side of the polarizer is, for example, a tri-layer. A known protective film such as acetyl cellulose (TAC) may be laminated.

  The laminated optical film and the polarizer of the present invention are bonded to each other, and the protective film and the polarizer are bonded to each other through a known adhesive or pressure-sensitive adhesive such as a pressure-sensitive adhesive, a thermosetting adhesive, or a photocurable adhesive. Can be suitably manufactured. As the pressure-sensitive adhesive and adhesive, those having excellent transparency are preferable. Specifically, natural rubber, synthetic rubber, vinyl acetate / vinyl chloride copolymer, polyvinyl ether, polyvinyl alcohol, acrylic resin, modified polyolefin resin, etc. A curable adhesive prepared by adding a curing agent such as an isocyanate group-containing compound to the above-described resin having a functional group such as a hydroxyl group or an amino group; a polyurethane-based dry laminate adhesive; a synthetic rubber-based adhesive; Examples thereof include an epoxy adhesive.

<Liquid crystal display device>
The liquid crystal display device of the present invention has the polarizing plate of the present invention.
Since the liquid crystal display device of the present invention has a laminated optical film or polarizing plate having a high contrast ratio when the screen is viewed from an oblique direction and small optical unevenness, a uniform display is possible.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. “Parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified. Moreover, room temperature is 25 degreeC.

Various measurements and evaluations were performed as follows.
[Polymerization reaction rate]
Place the weighed polymerization reaction solution in an aluminum container, heat to a constant temperature on a hot plate heated to 300 ° C., remove residual monomer and solvent, measure the weight of the remaining polymer, and calculate the theoretical weight. The polymerization reaction rate (%) was determined from the ratio with the combined production amount.

[Hydrogen addition rate]
The nuclear magnetic resonance spectrometer (NMR) was an AVANCE 500 manufactured by Bruker, and the measurement solvent was ¹ H-NMR with d-chloroform. 5.1-5.8 ppm vinylene group, 3
. The hydrogenation rate (%) was calculated after calculating the composition of the monomer from the integrated value of 7 ppm methoxy group and 0.6 to 2.8 ppm aliphatic proton.

[Glass transition temperature (Tg)]
The glass transition temperature (Tg) (° C.) was measured using a differential scanning calorimeter (trade name: DSC6200, manufactured by Seiko Instruments Inc.) under the condition of a temperature increase rate of 20 ° C./min according to JIS K7121.

[Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)]
Gel permeation chromatography (Tosoh Co., Ltd. HLC-8220GPC, column: Tosoh Co., Ltd. guard column H _XL- H, TSK gel G7000H _XL , two TSKgel GMH _XL , TSK gel G2000H _XL , sequentially connected, solvent: Tetrahydrofuran, flow rate: 1 mL / min, sample concentration: 0.7 to 0.8% by weight, injection amount: 70 μL, measurement temperature: 40 ° C., detector: RI (40 ° C.), standard material: manufactured by Tosoh Corporation Using TSK standard polystyrene), the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were measured. “Mn” is the number average molecular weight.

[Logarithmic viscosity]
Using an Ubbelohde viscometer, sample concentration 0.5 g / dL in chlorobenzene, temperature 30
The logarithmic viscosity (dL / g) was measured at 0 ° C.

[Film thickness]
The cross section of the laminated optical film was measured with an optical microscope. When the cross section is not suitable for microscopic observation, the cross section is embedded in an epoxy resin, sliced using a microtome RV-240 manufactured by Daiwa Koki Co., Ltd. The thickness (μm) was measured.

[In-plane retardation R555, NZ coefficient]
It measured using the automatic birefringence meter (Oji Scientific Instruments Co., Ltd. make, KOBRA-21ADH). The in-plane retardation R550 at a wavelength of 550 nm was determined by regression calculation of the actually measured values at wavelengths of 546.0 nm and 747.3 nm using the Cauchy equation. The NZ coefficient was determined from the in-plane retardation of the film, the oblique retardation from the polar angle of 40 degrees, the film thickness and the average film refractive index.

[Adhesion]
Adhesion was confirmed by a method in which a laminated optical film was attached to a glass plate with a double-sided tape, and a cutter blade was inserted between the layers to separate them. The cutter blade does not enter between the layers and does not peel off, “◎”, the cutter blade enters the layer, and the peeled portion can be produced, but from there it cannot be peeled continuously from “○”, The cutter blade entered between the layers and continuously peeled from the peeled portion was designated as “x”.

[Single transmittance, degree of polarization]
The single transmittance (%) and the degree of polarization (%) of the polarizing plate were measured using V-7300 manufactured by JASCO Corporation.

[Brightness contrast ratio]
Using an “EZ contrast-XL88” manufactured by ELDIM, the luminance contrast ratio of the liquid crystal display device was measured in a dark room with an illuminance of 1 lx or less.

Synthesis Example 1 Synthesis of Cyclic Olefin Resin (A1) 8-Methyl-8-methoxycarbonyltetracyclo represented by the following formula (7) [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene (215 parts) and bicyclo [2] represented by the following formula (8)
. 2.1] 35 parts of hept-2-ene, 18 parts of 1-hexene (molecular weight regulator) and 750 parts of toluene (solvent for ring-opening polymerization reaction) are charged into a nitrogen-substituted reaction vessel, and this solution is charged. Heated to 60 ° C. Next, 0.62 parts of a toluene solution of triethylaluminum (1.5 mol / L) as a polymerization catalyst and tungsten hexachloride modified with t-butanol and methanol (t-butanol: methanol: tungsten) were added to the solution in the reaction vessel. A toluene solution (concentration of 0.05 mol / L) of 0.35 mol: 0.3 mol: 1 mol) was added, and this solution was heated and stirred at 80 ° C. for 3 hours to cause a ring-opening polymerization reaction. A ring polymer solution was obtained. The polymerization reaction rate in this polymerization reaction was 97%, and the obtained ring-opened polymer had a logarithmic viscosity measured in chloroform at 30 ° C. of 0.75 dL / g.

1,000 parts of the ring-opening polymer solution thus obtained was charged into an autoclave, and 0.12 part of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the ring-opening polymer solution. Then, the hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm ² and a reaction temperature of 165 ° C. After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. This reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a cyclic olefin resin (A1) as a hydrogenated polymer.

  The resin A1 thus obtained had a hydrogenation rate of 99.9%, a glass transition temperature (Tg) of 125 ° C., a number average molecular weight (Mn) of 32,000, and a weight average molecular weight (Mw) of 137,000. 000, molecular weight distribution (Mw / Mn) was 4.29, and logarithmic viscosity was 0.69 dl / g. Table 1 shows the physical property values of the resin (A1).

[Synthesis Example 2] Synthesis of Cyclic Olefin Resin (A2) 8-Methyl-8-methoxycarbonyltetracyclo represented by the above formula (7) [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene (200 parts) and bicyclo [2] represented by the above formula (8)
. 2.1] Cyclic olefin resin (A2) which is a hydrogenated polymer in the same manner as in Synthesis Example 1 except that 50 parts of hept-2-ene and 18 parts of 1-hexene (molecular weight regulator) were used. )

  With respect to the obtained resin A2, the hydrogenation rate was 99.9%, the glass transition temperature (Tg) was 105 ° C., the Mn was 33,000, the Mw was 131,000, the molecular weight distribution (Mw / Mn) was 3.97, The logarithmic viscosity was 0.60 dL / g. Table 1 shows the physical property values of the resin (A2).

[Synthesis Example 3] Synthesis of Cyclic Olefin Resin (A3) Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene 53 parts and 8-ethylidenetetracyclo [4.4.0.1 ^2,5 represented by the following formula (10)
. 1, ¹⁰ ] -3-dodecene 46 parts and tricyclo [4.3.0.1 ^2,5 ] -deca-3,7-diene 66 parts represented by the following formula (11): A cyclic olefin that is a hydrogenated polymer in the same manner as in Synthesis Example 1 except that the amount of 1-hexene (molecular weight regulator) added is 22 parts and cyclohexane is used in place of toluene as a solvent for the ring-opening polymerization reaction. A resin (A3) was obtained.

  With respect to the obtained resin A3, the hydrogenation rate was 99.9%, the glass transition temperature (Tg) was 125 ° C., Mn was 30,000, Mw was 122,000, and the molecular weight distribution (Mw / Mn) was 4.07. The logarithmic viscosity was 0.63 dL / g. Table 1 shows each physical property value of the resin (A3).

[Synthesis Example 4] Synthesis of vinyl aromatic resin (B1) In a glass flask equipped with a stirrer, a condenser and a thermometer, 127.87 g (1.23 mol) of styrene, 13.33 g (0.136 mol) of maleic anhydride, Toluene 75 g as a solvent and 1,1′-azobis (cyclohexane-1-carbonitrile) 0.67 g (2.7 mmol) as a radical initiator were added, heated to 90 ° C., and reacted for 15 hours. A part of this polymerization solution was taken out and the reaction rate was measured and found to be 87%. Moreover, it was Mw = 129,900 and Mw / Mn = 2.00 when the molecular weight was measured.

  The obtained polymerization reaction solution was diluted with tetrahydrofuran and coagulated in a large amount of methanol to recover and purify the polymer, followed by drying for 2 days in an 80 ° C. vacuum dryer. When the molecular weight and logarithmic viscosity of the obtained vinyl aromatic resin (B1) were measured, Mw was 135,000 (Mw / Mn = 1.85), logarithmic viscosity was 0.46 dL / g, and yield was 80. %Met. The copolymer composition ratio determined by NMR was as prepared. The obtained polymer was a styrene-maleic anhydride copolymer, and the glass transition temperature was 128 ° C. Table 1 shows each physical property value of the resin (B1).

[Synthesis Example 5] Synthesis of Vinyl Aromatic Resin (B2) 145.6 g (1.40 mol) of styrene in a glass flask equipped with a stirrer, a condenser and a thermometer, 75 g of toluene as a solvent, and 1, 1 as a radical initiator 0.67 g (2.7 mmol) of 1′-azobis (cyclohexane-1-carbonitrile) was added, heated to 90 ° C., and reacted for 15 hours. A part of this polymerization solution was taken out and the reaction rate was measured to be 93%.

  The obtained polymerization reaction solution was diluted with tetrahydrofuran and coagulated in a large amount of methanol to recover and purify the polymer, followed by drying for 2 days in an 80 ° C. vacuum dryer. When the molecular weight and logarithmic viscosity of the obtained vinyl aromatic resin (B2) were measured, Mw was 168,300 (Mw / Mn = 1.68), logarithmic viscosity was 0.42 dL / g, and yield was 87. %Met. The obtained polymer was polystyrene and the glass transition temperature was 102 ° C. Table 1 shows the physical property values of the resin (B2).

[Synthesis Example 6] Synthesis of vinyl aromatic resin (B3) 126.88 g (1.22 mol) of styrene and 15.65 g (0.182 mol) of methacrylic acid in a glass flask equipped with a stirrer, a condenser and a thermometer and purged with nitrogen. Then, 75 g of toluene as a solvent and 0.67 g (2.7 mmol) of 1,1′-azobis (cyclohexane-1-carbonitrile) as a radical initiator were added, heated to 90 ° C., and reacted for 15 hours. A part of this polymerization solution was taken out and the reaction rate was measured and found to be 90%.

  The obtained polymerization reaction solution was diluted with tetrahydrofuran and coagulated in a large amount of methanol to recover and purify the polymer, followed by drying for 2 days in an 80 ° C. vacuum dryer. When the molecular weight and logarithmic viscosity of the obtained vinyl aromatic resin (B3) were measured, Mw was 223,000 (Mw / Mn = 2.35), logarithmic viscosity was 0.54 dL / g, and yield was 85. %Met. The obtained polymer was polystyrene and the glass transition temperature was 128 ° C. Table 1 shows the physical property values of the resin (B3).

[Preparation Example] Preparation of water-based adhesive 250 parts of distilled water was charged into a reaction vessel, 90 parts of butyl acrylate, 8 parts of 2-hydroxyethyl methacrylate, 2 parts of divinylbenzene, and potassium oleate in an amount of 0. 1 part was added, and this was stirred with a stirring blade made of Teflon (registered trademark) and dispersed. After purging the inside of the reaction vessel with nitrogen, the temperature of the system was raised to 50 ° C., and 0.2 part of potassium persulfate was added to initiate polymerization. After 2 hours, 0.1 part of potassium persulfate was further added, the system was heated to 80 ° C., and the polymerization reaction was continued for 1 hour to obtain a polymer dispersion.

  Next, by using an evaporator, the polymer dispersion liquid is concentrated until the solid content concentration becomes 70%, whereby an aqueous adhesive (adhesive having a polar group) composed of an aqueous dispersion of an acrylic ester polymer. Got.

  The acrylic ester polymer constituting the aqueous adhesive thus obtained has a MPC of 69,000 and Mw of 135,000 by GPC, and a logarithmic viscosity measured in chloroform at 30 ° C. is 1 .2 dL / g.

[Production Example 1] Production of Polarizer A roll-shaped polyvinyl alcohol film having a film thickness of 120 μm was prepared as a 30 ° C. aqueous solution having an iodine concentration of 0.03% by weight and a potassium iodide concentration of 0.5% by weight. After continuous uniaxial stretching (pre-stretching) in the longitudinal direction at a stretching ratio of 3 times in a dye bath, crosslinking at 55 ° C. of an aqueous solution having a boric acid concentration of 5% by weight and a potassium iodide concentration of 8% by weight In a bath, the film was further uniaxially stretched (post-stretched) in the longitudinal direction at a stretch ratio of 2 and dried to obtain a take-up roll-shaped polarizer.

[Production Example 2] Production of Cyclic Olefin Resin Film (A0) and Rear Side Polarizing Plate (P0) A hot air dryer in which dry air was passed through the pellets of cyclic olefin resin (A1) obtained in Synthesis Example 1 After being used and dried at 100 ° C. for 5 hours, it was extruded downstream using a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd .; TEM-48) and a gear pump, and a nominal aperture of 10 μm was made by Nippon Seisen. Melt filtration was performed using a metal fiber sintered filter, and the film was extruded at 280 ° C. using a coat hanger type T die. At this time, the difference between the maximum pressure at the outlet of the extruder and the average pressure was 0.1%.

The film-like molten resin is measured by using a ten-point average roughness Rz _JIS maximum value Rmax (in JIS B0601).
cast to a roll coated with aluminum oxide having a surface thickness of 0.1 μm), and then using a peeling roll having a surface roughness coated with aluminum oxide and having a 10-point average roughness Rz _JIS maximum value Rmax (μm) of 0.1. It peeled. The absolute value of the difference between the maximum or minimum value of the roll take-up speed at that time and the average take-up speed was 0.04%. A 68 μm-thick cyclic olefin resin film (A0) roll was obtained by the above method. The in-plane retardation R550 of the obtained film was 0 to 2 nm, and Rth was 5 to 10 nm. Note that “Rth” is one of indices indicating the thickness direction retardation, and is a value at a wavelength of 550 nm. Rth is represented by {(nx + ny) / 2-nz} × d, where nx is the in-plane maximum refractive index at the optical film measurement point, and is substantially parallel to the film longitudinal direction. ny represents the refractive index in the direction perpendicular to nx in the plane, nz represents the refractive index in the stretched film thickness direction perpendicular to nx and ny, and d represents the film thickness (nm) at the measurement point.

  This film roll was made to have a roll-shaped film aligned on one side of the polarizer obtained in Production Example 1, and both were continuously pasted using the aqueous adhesive obtained in Preparation Example, and the other side of the polarizer was A film made of triacetyl cellulose (TAC) having a thickness of 80 μm was stuck to the surface of the surface using an adhesive made of a PVA aqueous solution having a concentration of 5% to obtain a rear side polarizing plate (P0). The obtained polarizing plate had a single transmittance of 42.2% and a degree of polarization of 99.9%.

[Production Example 3] Production of transparent resin film (D1) Using the pellets of the cyclic olefin resin (A1) obtained in Synthesis Example 1, in the same manner as in Production Example 1, a cyclic olefin resin film having a thickness of 100 µm ( FA1) was obtained. This film was longitudinally stretched at a stretching temperature of 145 ° C. and a stretch ratio of 1.5 times to obtain a transparent resin film (D1) roll having a thickness of 80 μm. The in-plane retardation R550 of the obtained film D1 was 90 nm, and NZ = 1.02.

[Production Example 4] Production of transparent resin film (D2) Using the pellets of cyclic olefin resin (A1) obtained in Synthesis Example 1, the same method as in Production Example 1 and a 130 μm thick cyclic olefin resin film (FA2) was obtained. This film was stretched transversely by a tenter at a stretching temperature of 145 ° C. and a stretching ratio of 3.0 times to obtain a transparent resin film (D2) roll having a thickness of 45 μm. The in-plane retardation R550 of the obtained film D2 was 90 nm, and NZ = 1.28.

[Production Example 5] Production of transparent resin film (D3) Using the cyclic olefin resin film (FA2) obtained in Production Example 4, the tenter was transversely stretched at a stretching temperature of 145 ° C and a stretching ratio of 3.3 times to obtain a thickness. A 40 μm transparent resin film (D3) roll was obtained. In-plane retardation R550 of the obtained film D3 was 120 nm, and NZ was 1.25.

[Example 1]
(Manufacture of laminated optical film (E1))
The cyclic olefin resin (A1) pellets and the vinyl aromatic resin (B1) pellets were each dried at 100 ° C. for 5 hours using a hot air dryer in which dry air was passed. These pellets were coextruded under the conditions of a molten resin temperature of 260 ° C. and a T die lip opening width of 600 mm using two series of melt extruders having a 65 mmφ screw and a 50 mmφ screw, thereby obtaining A1 (50 μm) / B1. A coextruded film roll having a configuration of (150 μm) was obtained.

  This co-extruded film roll was transversely stretched with a tenter at a stretching temperature of 137 ° C. and a stretching ratio of 3.0 times to obtain a stretched film (C1) roll having a thickness of 68 μm. The in-plane retardation R550 of the stretched film C1 was 95 nm and NZ was −0.32, and when the adhesion between the films was confirmed, the adhesion was good without peeling.

  The longitudinal direction of the obtained stretched film (C1) roll and the longitudinal direction of the transparent resin film (D1) roll obtained in Production Example 3 are aligned, and the vinyl aromatic resin (B1) becomes the transparent resin film (D1). Both were continuously pasted using an acrylic transparent adhesive film to obtain a laminated optical film (E1) roll. The obtained laminated optical film had an in-plane retardation R550 = 185 nm, NZ = 0.70, and a thickness of 170 μm.

(Production of polarizing plate (P1) and evaluation of liquid crystal display device)
The longitudinal direction of the laminated optical film (E1) roll obtained is aligned with the longitudinal direction of the polarizer roll obtained in Production Example 1 (absorption axis of polarizer = stretching direction = film longitudinal direction is the optical axis of the laminated optical film) The cyclic olefin resin (A1) faces the polarizer side, and both are continuously pasted using the aqueous adhesive obtained in the preparation example, and the other side of the polarizer A TAC film having a thickness of 80 μm was pasted using an adhesive made of a PVA aqueous solution having a concentration of 5% to obtain a polarizing plate (P1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively.

  In order to evaluate the characteristics of the polarizing plate (P1), the polarized light applied to the front and back surfaces of the liquid crystal panel of Hitachi Ltd. liquid crystal television (model number L37-XR01-1) in IPS mode. The plate and the retardation film are peeled off, and at the peeled place, the rear side polarizing plate (P0) obtained in Production Example 2 is on the light source side (back side), and the polarizing plate (P1) is on the viewing side (front side). It was made to be the same as the transmission axis of the polarizing plate that was originally bonded, and was bonded using an acrylic transparent adhesive film. At this time, both the back surface and the front surface were bonded using an acrylic transparent adhesive film so that the TAC film in the polarizing plate was the outermost surface on both sides of the panel. When the luminance contrast ratio of the liquid crystal display device having this polarizing plate was measured, it was a high value as the minimum value: 85 in the range of all directions and polar angles of 0 to 80 degrees, and no unevenness was observed visually.

  A vertical sectional view of the liquid crystal display device showing the order of stacking films and the like is shown in FIG. In addition, the liquid crystal cell 5 in the figure is a state in which the polarizing plate and the retardation film previously attached to the front and back surfaces of the liquid crystal panel are removed, and the transparent adhesive film layer is not shown. .

[Example 2]
(Manufacture of laminated optical film (E2))
In the same manner as in Example 1, a coextruded film roll having a configuration of A1 (40 μm) / B1 (120 μm) was obtained. This co-extruded film roll was longitudinally stretched at a stretching temperature of 145 ° C. and a stretching ratio of 1.8 times to obtain a stretched film (C2) roll having a thickness of 115 μm. The in-plane retardation of stretched film C2 was R550 = 95 nm and NZ = −0.03, and the adhesion between the films was confirmed.

  The longitudinal direction of the obtained stretched film C2 roll and the longitudinal direction of the transparent resin film D2 roll obtained in Production Example 4 are aligned so that the vinyl aromatic resin B1 layer faces the transparent resin film D2, and acrylic Both were continuously pasted using a transparent adhesive film to obtain a laminated optical film (E2) roll. The obtained laminated optical film had an in-plane retardation R550 = 185 nm, NZ = 0.62, and a thickness of 182 μm.

(Production of polarizing plate (P2) and evaluation of liquid crystal display device)
A polarizing plate (P2) was obtained in the same manner as in Example 1 except that the laminated optical film (E2) was used in place of the laminated optical film (E1) and the transparent resin film D2 faced the polarizer. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively. The luminance contrast ratio of the liquid crystal display device was measured in the same manner as in Example 1 except that the polarizing plate (P2) was used instead of the polarizing plate (P1). Minimum value: 82, which is a high numerical value, and no unevenness was visually observed.

A vertical cross-sectional view of the liquid crystal display device showing the stacking order of films and the like is shown in FIG.
[Example 3]
(Manufacture of laminated optical film (E3))
In the same manner as in Example 1, a coextruded film roll having a configuration of A1 (50 μm) / B1 (150 μm) was obtained. This co-extruded film roll was longitudinally stretched at a stretching temperature of 140 ° C. and a stretching ratio of 1.7 times, and then stretched transversely by a tenter at a stretching temperature of 135 ° C. and a stretching ratio of 2.5 times, and a stretched film having a thickness of 60 μm (C3) Got a roll. The in-plane retardation R550 ≦ 2 nm and NZ ≦ −50 (Rth = −100 nm) of the stretched film C3 were confirmed. When the adhesion between the films was confirmed, the adhesion was good without peeling.

The longitudinal direction of the obtained stretched film C3 roll is aligned with the longitudinal direction of the transparent resin film D3 roll obtained in Production Example 5 so that the vinyl aromatic resin B1 layer faces the transparent resin film D3, and acrylic. Both were continuously pasted using a transparent adhesive film to obtain a laminated optical film (E3) roll. The obtained laminated optical film had an in-plane retardation R550 = 121 nm, NZ = 0.42, and a thickness of 123 μm.

(Production of polarizing plate (P3) and evaluation of liquid crystal display device)
A polarizing plate (P3) was obtained in the same manner as in Example 1 except that the laminated optical film (E3) was used in place of the laminated optical film (E1) and the transparent resin film D3 faced the polarizer. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.1% and 99.9%, respectively. The luminance contrast ratio of the liquid crystal display device was measured in the same manner as in Example 1 except that the polarizing plate (P3) was used instead of the polarizing plate (P1). The minimum value is a high value of 90, and no unevenness was observed visually.

A vertical cross-sectional view of the liquid crystal display device showing the stacking order of films and the like is shown in FIG.
[Example 4]
(Manufacture of laminated optical film (E4))
By using the cyclic olefin resin (A1) and the vinyl aromatic resin (B1) and changing the flow path of the molten resin, the laminated structure was set to A1 (30 μm) / B1 (150 μm) / A1 (30 μm). A coextruded film roll was obtained. This co-extruded film roll was longitudinally stretched at a stretching temperature of 143 ° C. and a stretching ratio of 2.0 times to obtain a stretched film (C4) roll having a thickness of 128 μm. The in-plane retardation R550 of the stretched film C4 = 550 nm and NZ = −0.02, and the adhesion between the films was confirmed.

  The longitudinal direction of the obtained stretched film C4 roll is aligned with the longitudinal direction of the transparent resin film D2 roll obtained in Production Example 4, and the cyclic olefin-based resin A1 layer is a transparent resin (necessarily because of the three-layer structure). Both were continuously pasted using an acrylic transparent adhesive film so as to face the film D2, and a laminated optical film (E4) roll was obtained. The obtained laminated optical film had an in-plane retardation R550 = 183 nm, NZ = 0.65, and a thickness of 195 μm.

(Production of polarizing plate (P4) and evaluation of liquid crystal display device)
A polarizing plate (P4) was obtained in the same manner as in Example 1 except that the laminated optical film (E4) was used in place of the laminated optical film (E1) and the transparent resin film D2 faced the polarizer. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.9% and 99.9%, respectively. The luminance contrast ratio of the liquid crystal display device was measured in the same manner as in Example 1 except that the polarizing plate (P4) was used instead of the polarizing plate (P1). The minimum value is a high value of 80, and no unevenness was observed visually.

Note that FIG. 3 shows a vertical cross-sectional view of the liquid crystal display device showing the stacking order of films and the like.
[Example 5]
(Manufacture of laminated optical film (E5))
A coextruded film roll having a structure of A2 (50 μm) / B1 (100 μm) was obtained in the same manner as in Example 1 except that the cyclic olefin resin (A2) and the vinyl aromatic resin (B1) were used. This co-extruded film roll was transversely stretched with a tenter at a stretching temperature of 140 ° C. and a stretching ratio of 2.0 times to obtain a stretched film (C5) roll having a thickness of 77 μm. The in-plane retardation of the stretched film (C5) was R550 = 96 nm and NZ = −0.35, and when the adhesion between the films was confirmed, the adhesion was good without peeling.

  The longitudinal direction of the obtained stretched film (C5) roll and the longitudinal direction of the transparent resin film (D1) roll obtained in Production Example 3 are aligned so that the vinyl aromatic resin (B1) becomes the transparent resin film (D1). Both were continuously pasted using an acrylic transparent adhesive film to obtain a laminated optical film (E5) roll. The obtained laminated optical film had an in-plane retardation R550 = 186 nm, NZ = 0.65, and a thickness of 180 μm.

(Production of polarizing plate (P5) and evaluation of liquid crystal display device)
A polarizing plate (P5) was obtained in the same manner as in Example 1 except that the laminated optical film (E5) was used instead of the laminated optical film (E1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively. The luminance contrast ratio of the liquid crystal display device was measured in the same manner as in Example 1 except that the polarizing plate (P5) was used instead of the polarizing plate (P1). The minimum value is a high value of 90, and no unevenness was observed visually.

A vertical sectional view of the liquid crystal display device showing the order of stacking films and the like is shown in FIG.
[Example 6]
(Manufacture of laminated optical film (E6))
In the same manner as in Example 1, a coextruded film roll having a configuration of A1 (40 μm) / B3 (110 μm) was obtained. This co-extruded film roll was longitudinally stretched at a stretching temperature of 145 ° C. and a stretching ratio of 1.8 times to obtain a stretched film (C6) roll having a thickness of 108 μm. The in-plane retardation R550 of the stretched film C6 was 95 nm and NZ was 0.00, and the adhesion between the films was confirmed.

  The longitudinal direction of the obtained stretched film (C6) roll is aligned with the longitudinal direction of the transparent resin film (D2) roll obtained in Production Example 4, and the vinyl aromatic resin (B3) faces the transparent resin film D2. Thus, both were continuously pasted using an acrylic transparent adhesive film to obtain a laminated optical film (E6) roll. The obtained laminated optical film had an in-plane retardation R550 = 185 nm, NZ = 0.60, and a thickness of 175 μm.

(Production of polarizing plate (P6) and evaluation of liquid crystal display device)
A polarizing plate (P6) is obtained in the same manner as in Example 1 except that the laminated optical film (E6) is used instead of the laminated optical film (E1) and the transparent resin film (D2) faces the polarizer. It was. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.1% and 99.9%, respectively. The luminance contrast ratio of the liquid crystal display device was measured in the same manner as in Example 1 except that the polarizing plate (P6) was used instead of the polarizing plate (P1). The minimum value is a high value of 88, and no unevenness was observed visually.

A vertical cross-sectional view of the liquid crystal display device showing the stacking order of films and the like is shown in FIG.
[Comparative Example 1]
(Manufacture of laminated optical film (E7))
A coextruded film roll having a configuration of A3 (50 μm) / B1 (150 μm) was obtained in the same manner as in Example 1 except that the cyclic olefin resin (A3) and the vinyl aromatic resin (B1) were used. This co-extruded film roll was transversely stretched with a tenter at a stretching temperature of 137 ° C. and a stretching ratio of 3.0 times to obtain a stretched film (C7) roll having a thickness of 66 μm. In-plane retardation of stretched film (C7) R550 = 95 nm, NZ = −0.30, and when the adhesion between the films was confirmed, a cutter blade entered between the layers, which could be peeled continuously from there. It was.

  The longitudinal direction of the obtained stretched film (C7) roll and the longitudinal direction of the transparent resin film (D1) roll obtained in Production Example 3 are aligned so that the vinyl aromatic resin (B1) becomes the transparent resin film (D1). Both were continuously pasted using an acrylic transparent adhesive film to obtain a laminated optical film (E7) roll. The obtained laminated optical film had an in-plane retardation R550 = 185 nm, NZ = 0.70, and a thickness of 168 μm. However, the A3 / B1 layer was peeled off at some points during transport in the roll width direction.

[Comparative Example 2]
(Manufacture of laminated optical film (E8))
A coextruded film roll having a configuration of A1 (50 μm) / B2 (150 μm) was obtained in the same manner as in Example 1 except that the cyclic olefin resin (A1) and the vinyl aromatic resin (B2) were used. This co-extruded film roll was transversely stretched by a tenter at a stretching temperature of 130 ° C. and a stretching ratio of 2.5 times to obtain a stretched film (C8) roll having a thickness of 80 μm. The in-plane retardation of the stretched film (C8) was R550 = 135 nm and NZ = 1.30, and when the adhesion between the films was confirmed, the adhesion was good without peeling.

  The longitudinal direction of the obtained stretched film (C8) roll and the longitudinal direction of the transparent resin film (D1) roll obtained in Production Example 3 are aligned so that the vinyl aromatic resin (B2) becomes the transparent resin film (D1). Both were continuously pasted using an acrylic transparent adhesive film to obtain a laminated optical film (E8) roll. The obtained laminated optical film had an in-plane retardation R550 = 45 nm, NZ = 3.5, and a thickness of 183 μm.

(Production of polarizing plate (P8) and evaluation of liquid crystal display device)
A polarizing plate (P8) was obtained in the same manner as in Example 1 except that the laminated optical film (E8) was used instead of the laminated optical film (E1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively. The luminance contrast ratio of the liquid crystal display device was measured in the same manner as in Example 1 except that the polarizing plate (P8) was used instead of the polarizing plate (P1). Minimum value: 5. Since the glass transition temperature of the vinyl aromatic resin (B2) used for the laminated optical film (E8) is lower than that of the cyclic olefin resin (A1), B2 does not exhibit a predetermined phase difference when stretched. Therefore, the laminated optical film (E8) is not a desirable retardation, and the contrast ratio in the oblique direction is poor.

A vertical sectional view of the liquid crystal display device showing the order of stacking films and the like is shown in FIG.
The results of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 2. The “optical axis direction” (= slow axis direction) in the table means the slow axis direction of the laminated stretched film (C) (= in-plane maximum refractive index direction) and the slow phase of the transparent resin film (D). When determined in combination with the axial direction and parallel to the longitudinal direction of the laminated optical film, it is expressed as “MD”, and when orthogonal to the longitudinal direction of the laminated optical film, it is expressed as “TD”.

FIG. 1 is a vertical cross-sectional view of a liquid crystal display device showing the stacking order of films and the like in Example 1, Example 5, and Comparative Example 2. In addition, the visual recognition side TAC film and the transparent adhesive film layer are not illustrated. FIG. 2 is a vertical cross-sectional view of the liquid crystal display device according to the second embodiment and the third embodiment showing the stacking order of films and the like. In addition, the visual recognition side TAC film and the transparent adhesive film layer are not illustrated. FIG. 3 is a vertical sectional view of the liquid crystal display device according to the fourth embodiment showing the order of stacking films and the like. In addition, the visual recognition side TAC film and the transparent adhesive film layer are not illustrated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Polarizer 2 ... Cyclic olefin resin (A)
3 ... Vinyl aromatic resin (B)
4 ... Transparent resin film (D)
5 ... Liquid crystal cell 6 ... Rear-side polarizing plate (P0)
7 ... Co-extruded film

Claims (11)

(C) a step of laminating and forming a cyclic olefin resin (A) and a vinyl aromatic resin (B) by a coextrusion method to obtain a coextruded film;
A step (β) of stretching the coextruded film to obtain a laminated stretched film (C), and a step of laminating the laminated stretched film (C) on a transparent resin film (D) to obtain a laminated optical film (E) (Γ)
A method for producing a laminated optical film comprising:
The method for producing a laminated optical film, wherein the laminated optical film (E) satisfies the following formulas (i) and (ii):
70 (nm) ≦ R550 ≦ 350 (nm) (i)
(In the formula, R550 represents an in-plane retardation at a wavelength of 550 nm.)
0 <NZ <1 (ii)
(In the formula, NZ represents a coefficient represented by NZ = (nx−nz) / (nx−ny) at a wavelength of 550 nm. Here, nx represents an in-plane maximum refractive index, and ny represents: (In-plane represents the refractive index in the direction perpendicular to nx, and nz represents the refractive index in the thickness direction perpendicular to nx and ny.) The cyclic olefin resin (A) is composed of a copolymer having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2). A method for producing a laminated optical film.

(In the formula, m represents an integer of 1 or more, p represents an integer of 0 or more,
X independently represents a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —.
R ^{1 to} R ⁴ each independently represent a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. Or a polar group,
R ¹ and R ² and / or R ³ and R ⁴ may be integrated to form a divalent hydrocarbon group,
R ¹ or R ² and R ³ or R ⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring, and the carbocyclic or heterocyclic ring may be a monocyclic structure or a polycyclic structure.
However, at least one group of R ^{1 to} R ⁴ includes atoms other than carbon atoms and hydrogen atoms. )

Wherein Y is independently a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —
R ^{5 to} R ⁸ each independently represent a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms that may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom. Or a polar group,
R ⁵ and R ⁶ and / or R ⁷ and R ⁸ may be integrated to form a divalent hydrocarbon group,
R ⁵ or R ⁶ and R ⁷ or R ⁸ may be bonded to each other to form a carbocyclic or heterocyclic ring, and the carbocyclic or heterocyclic ring may be a monocyclic structure or a polycyclic structure. )   The method for producing a laminated optical film according to claim 1 or 2, wherein the vinyl aromatic resin (B) is a styrene- (meth) acrylic acid copolymer.   The method for producing a laminated optical film according to claim 1 or 2, wherein the vinyl aromatic resin (B) is a styrene-maleic anhydride copolymer.   The method for producing a laminated optical film according to any one of claims 1 to 4, wherein the cyclic olefin resin (A) and the vinyl aromatic resin (B) are in direct contact with each other to form a laminated film. The glass transition temperature (TgA) of the cyclic olefin resin (A) and the glass transition temperature (TgB) of the vinyl aromatic resin (B) satisfy the relationship represented by the following formula (iii),
The method for producing a laminated optical film according to any one of claims 1 to 5, wherein the stretching temperature in the step (β) is TgA or higher and TgB or higher.
−10 (° C.) ≦ TgB−TgA (iii)   The method for producing a laminated optical film according to claim 1, wherein the transparent resin film (D) is made of a cyclic olefin-based resin and uniaxially stretched in the film width direction or the longitudinal direction.   The method for producing a laminated optical film according to any one of claims 1 to 7, wherein the laminated stretched film (C) and the transparent resin film (D) are continuously laminated by a roll-to-roll method.   A laminated optical film obtained by the production method according to claim 1.   A polarizing plate comprising the laminated optical film according to claim 9 laminated on at least one surface of a polarizer via an adhesive or a pressure-sensitive adhesive.   A liquid crystal display device comprising the polarizing plate according to claim 10.

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