JP5186991B2 - Method for producing laminated optical film, laminated optical film, polarizing plate and liquid crystal display device - Google Patents

Description

  The present invention relates to a laminated optical film that realizes excellent viewing angle characteristics in a liquid crystal display device, a manufacturing method thereof, a polarizing plate using the film, and a liquid crystal display device.

The retardation film is generally used for the purpose of compensating the viewing angle of the 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 them, the cyclic olefin film is attracting attention as a material for various optical components including a retardation film because it is excellent in transparency, heat resistance, dimensional stability, low photoelasticity and the like.

In recent years, in addition to the conventional TN mode, a high viewing angle liquid crystal mode such as a VA mode or an IPS mode has been put into practical use, and a liquid crystal display device (a liquid crystal television) has been widely used in television applications that require high image quality. For example, as a retardation film for a VA mode liquid crystal display device, a compensation method combining an A plate and a C plate and a compensation method combining one or two biaxial films are particularly effective in improving the viewing angle. It is known to be expensive.
However, even with these compensation methods, a color change when the screen is viewed from an oblique direction (hereinafter abbreviated as a color shift), for example, a place where it should be black in a black display state appears colored purple, The viewing angle compensation was insufficient. In order to improve this, there is a need for a retardation film having a so-called reverse wavelength dispersion property that the phase difference is smaller as the wavelength is shorter in the visible light region, and the phase difference is increased as the wavelength is longer. Are known. For example, Patent Document 1 proposes a method for realizing reverse wavelength dispersion by modifying a resin used for a retardation film. However, it has not been widely put into practical use because it becomes difficult to establish resin production conditions due to resin modification, and the strength, transparency, stability, etc. of the film are impaired.

As a method other than the modification of the resin, there is a method in which a layer having a specific retardation is laminated and the total retardation is controlled so as to have reverse wavelength dispersion. For example, Patent Document 2 proposes a method of realizing reverse wavelength dispersion by laminating a retardation layer made of a polymerizable liquid crystal and a resin film. However, a retardation layer made of a polymerizable liquid crystal has a high difficulty in production because it is necessary to control a layer having a thickness of about several microns with a thickness variation of several percent. In addition, with such a stacking method, a predetermined phase difference value and reverse wavelength dispersion can be obtained when observed from the front direction, but when observed from an oblique direction, the predetermined phase difference is caused by the effect of optical axis deviation. There is a problem that viewing angle compensation in an oblique direction cannot be performed.
As another method for laminating the retardation layer, Patent Document 3 proposes film formation and retardation film production by a coextrusion method. However, the adhesion of each layer is poor, and it is necessary to sandwich an adhesive layer between the layers, resulting in a problem that the layer configuration and the manufacturing apparatus become complicated. In addition, when a laminated film is formed by a coextrusion method, it is difficult to control the variation in the thickness and total thickness of each layer for each location, and the variation in retardation is likely to occur due to these variations. Therefore, there is a problem that uniform viewing angle cannot be compensated for, for example, the contrast ratio and color shift differ from place to place, and the screen display is not uniform. As described above, a method for increasing the contrast ratio from the oblique direction and reducing the color shift has not been sufficiently established, and an improvement has been demanded.

JP 2006-225626 A JP 2006-268033 A JP 2004-133313 A

  Excellent surface smoothness and thickness uniformity, heat resistance, high contrast ratio when viewing the screen from an oblique direction in a liquid crystal display device, and small color shift when viewing the screen from an oblique direction Another object of the present invention is to provide a laminated optical film that enables a more uniform screen display, a manufacturing method thereof, a polarizing plate and a liquid crystal display device using the same.

The method for producing a laminated optical film of the present invention comprises laminating a cyclic olefin resin film (hereinafter also referred to as “film (A)”) and a vinyl aromatic resin film (hereinafter also referred to as “film (B)”). Laminating by a method, obtaining a raw film in which a cyclic olefin resin layer (hereinafter also referred to as “A layer”) and a vinyl aromatic resin layer (hereinafter also referred to as “B layer”) are obtained; And a step of uniaxially stretching the obtained raw film in a direction orthogonal to the film longitudinal direction (hereinafter, also referred to as “lateral uniaxial stretching”). It is related with the manufacturing method of the laminated optical film which satisfy | fills all the characteristics represented by these.
R450 <R550 <R650 (i)
1.0 <R650 / R550 <1.2 (ii)
70 nm ≦ R550 ≦ 150 nm (iii)
[In the above formulas (i) to (iii), R450, R550, and R650 represent the in-plane retardation of the laminated optical film at wavelengths of 450 nm, 550 nm, and 650 nm, respectively. ]
The cyclic olefin resin film and vinyl aromatic resin film of the present invention in the production method of the present invention are each preferably formed by either a melt extrusion method or a solution casting method.

  The cyclic olefin-based resin in the production method of the present invention includes a repeating unit represented by the following formula (1) (hereinafter also referred to as “repeating unit (1)”) and a repeating unit represented by the following formula (2) (hereinafter referred to as “repeating unit”). And a copolymer having “repeating unit (2)”.

[Wherein, m is an integer of 1 or more, p is an integer of 0 or more, and X is independently a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —. R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon having 1 to 30 carbon atoms, which may have a linking group containing oxygen, nitrogen, sulfur or silicon 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, and 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. ]

[Wherein Y represents 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 each independently represents 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 oxygen, nitrogen, sulfur or silicon; 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 may be bonded to each other to form a carbocyclic or heterocyclic ring. The carbocycle or heterocycle may be a monocyclic structure or a polycyclic structure. ]

The vinyl aromatic resin in the production method of the present invention is preferably a styrene- (meth) acrylic acid copolymer.
The vinyl aromatic resin in the production method of the present invention is preferably a styrene-maleic anhydride copolymer.
In the production method of the present invention, the cyclic olefin resin layer and the vinyl aromatic resin layer are preferably in direct contact with each other.

In the production method of the present invention, it is preferable that the cyclic olefin resin and the vinyl aromatic resin satisfy the following formula (iv).
| TgA (° C.) − TgB (° C.) | ≦ 20 (° C.) (iv)
[Wherein, TgA represents the glass transition temperature of the cyclic olefin resin (hereinafter also referred to as “Tg”), and TgB represents the glass transition temperature of the vinyl aromatic resin. ]
The laminated optical film of the present invention is obtained by the production method of the present invention.

The laminated optical film of the present invention preferably satisfies the following formula (v).
1.0 ≦ NZ ≦ 3.0 (v)
[In the above formula (v), NZ is a coefficient represented by NZ = (nx−nz) / (nx−ny)]. Here, nx represents the maximum refractive index in the laminated optical film plane, ny represents the refractive index in the laminated optical film plane in the direction orthogonal to the maximum refractive index direction, and nz represents the refractive index in the laminated optical film thickness direction. These are all values at a wavelength of 550 nm. ]
In the laminated optical film of the present invention, both the glass transition temperature of the cyclic olefin resin and the glass transition temperature of the vinyl aromatic resin are preferably 110 ° C. or higher.

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.
The liquid crystal display device of the present invention has the polarizing plate of the present invention.

  The laminated optical film of the present invention has a high contrast ratio when the screen is viewed from an oblique direction in a liquid crystal display device, and a small color shift amount when the screen is viewed from an oblique direction, enabling a more uniform screen display. A liquid crystal display device is obtained.

[Method for producing laminated optical film]
The method for producing the laminated optical film of the present invention comprises:
A raw film in which a film (A) made of a cyclic olefin resin and a film (B) made of a vinyl aromatic resin are laminated by a lamination method, and a cyclic olefin resin layer and a vinyl aromatic resin layer are laminated. Obtaining
And a step of uniaxially stretching the obtained raw film in a direction perpendicular to the longitudinal direction of the film.

Cyclic Olefin Resin The cyclic olefin resin used in the present invention is preferably a co-polymer having a repeating unit (1) represented by the above formula (1) and a repeating unit (2) represented by the above formula (2). It is a coalescence. Furthermore, it is optional to include other repeating units as necessary.

In the formulas (1) and (2), R ^{1 to} R ⁸ are each a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom that may have a linking group containing oxygen, nitrogen, sulfur, or silicon 1 Represents a hydrocarbon group of ˜30; or a polar group. The above atoms and groups will be 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. Group and the like.
The substituted or unsubstituted hydrocarbon group may be directly bonded to the ring structure or may be bonded via a linking group. As the linking group, for example, a divalent hydrocarbon group having 1 to 10 carbon atoms (for example, an alkylene group represented by — (CH ₂ ) m — (wherein m is an integer of 1 to 10)); oxygen , A linking group containing nitrogen, sulfur or silicon (for example, a carbonyl group (—CO—), an oxycarbonyl group (—O (CO) —), a sulfone group (—SO ₂ —), an ether bond (—O—), Thioether bond (—S—), imino group (—NH—), amide bond (—NHCO—, —CONH—), siloxane bond (—OSi (R ₂ ) — (wherein R is an alkyl such as methyl or ethyl) Group)) etc., and 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. , An acyl group, an alkoxysilyl group, a sulfonyl-containing group, a 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; examples of the aryloxycarbonyl group include Examples include phenoxycarbonyl group, naphthyloxycarbonyl group, fluorenyloxycarbonyl group, biphenylyloxycarbonyl group and the like; examples of triorganosiloxy group include trimethylsiloxy group and triethylsiloxy group; Includes a trimethylsilyl group, a triethylsilyl group and the like; examples of the amino group include a primary amino group, and examples of the alkoxysilyl group include a trimethoxysilyl group and a triethoxysilyl group.

  The copolymer includes one or more monomers represented by the following formula (3) (hereinafter also referred to as “monomer (1)”) and one or more monomers represented by the following formula (4). And a monomer (hereinafter also referred to as “monomer (2)”).

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

(In the formula, definitions of R ⁵ , R ⁶ , R ⁷ and R ⁸ are as defined in formula (2).)

<Monomer (1)>
The repeating 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 the monomer (1) in combination of 2 or more types.

Tricyclo [5.2.1.0 ^2,6 ] -8-decene,
Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
Pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] -4-pentadecene,
Pentacyclo [7.4.0.1 ^2,5 . 1 ^9,12 . 0 ^8,13 ] -3-pentadecene,
Tricyclo [4.4.0.1 ^2,5 ] -3-undecene,
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,
Pentacyclo [8.4.0.1 ^2,5 . 1 ^9,12 . 0 ^8,13 ] -3-hexadecene,
Heptacyclo [8.7.0.1 ^3,6 . 1 ^{10, 17} . 1 ^{12, 15} . 0 ^2,7 . 0 ^11,16 ] -4-eicosene,
Heptacyclo [8.8.0.1 ^4,7 . 1 ^{11, 18} . 1 ^13,16 . 0 ^3,8 . 0 ^12,17 ] -5- ^Haneikosen ,
8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-phenyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-phenyltetracyclo [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 . ^{17, 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 (3), 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, and R 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. The presence of the polar group can improve the adhesion with the vinyl aromatic resin layer in the lamination by the lamination method.
Furthermore, at least one of R ² and R ⁴ is represented by formula (5):
^{_{- (CH 2) n COOR 9}} (5)
[Wherein n is usually 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 (1), is preferable in that the glass transition temperature and water absorption of the resulting copolymer can be easily controlled. Examples of the monovalent organic group represented by R ⁹ in the formula (5) include alkyl groups such as methyl group, ethyl group, and propyl group; aryl groups such as phenyl group, naphthyl group, anthracenyl group, and biphenylyl group; In addition, monovalent groups having an aromatic ring such as fluorenes such as diphenylsulfone and tetrahydrofluorene, and a heterocyclic ring such as a furan ring and an imide ring are exemplified.

In the formula (5), n is usually an integer of 0 to 5 as described above. However, the smaller the value of n, the higher the glass transition temperature of the copolymer obtained, which is preferable. Monomer (1) is preferred in that its synthesis is easy.
Further, in the above formula (3), the fact that an alkyl group is further bonded to the carbon atom to which the polar group represented by formula (5) is bonded balances the heat resistance and water absorption of the resulting copolymer. It is preferable when trying. The alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 2, and particularly preferably 1.
In addition, the monomer (1) in which m is 1 and p is 0 in the formula (3) 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 . ^{17, 10} ] -3-dodecene increases the glass transition temperature of the resulting copolymer, hardly receives any adverse effects such as deformation due to water absorption, and has good water absorption so that adhesion and adhesion to other materials are good. It is preferable because the property 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,
And 5- (4-phenylphenyl) bicyclo [2.2.1] hept-2-ene 4- (bicyclo [2.2.1] hept-5-en-2-yl) phenylsulfonylbenzene. it can.

Among these, the monomer (2) in which R ^{5 to} R ⁸ in the formula (4) are all hydrogen atoms, or any one is a hydrocarbon group having 1 to 30 carbon atoms and the other is a hydrogen atom, It is preferable in that the effect of improving the toughness of the obtained optical film is large, 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 and have improved resin toughness. It is preferable in that it can be used for adjusting the glass transition temperature and the phase difference can be ensured.

  In the present invention, the use ratio of the monomer (1) and the monomer (2) is usually in a weight ratio of monomer (1): monomer (2) = 95: 5 to 5:95, Preferably it is 95: 5-60: 40, More preferably, it is 95: 5-70: 30, More preferably, it is 95: 5-75: 25. If the proportion of monomer (1) is greater than the above range, the effect of improving toughness may not be expected. Conversely, if the proportion of monomer (1) is less than the above range, the glass transition temperature will be low and heat resistance will be reduced. May cause problems with sex.

  Moreover, in order to improve adhesiveness and adhesiveness with other materials, the repeating unit having a polar group in the total amount of the repeating unit (1) and the repeating unit (2) is usually 50 to 95 mol%, preferably 70 to 95. It is contained in an amount of 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 lamination by the lamination method.

<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 resin modification such as improvement in retardation, Tg adjustment, and improvement in moldability.
Furthermore, monomers in the presence of unsaturated hydrocarbon-based polymers having an olefinically unsaturated bond in the main chain such as polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-nonconjugated diene copolymer, polynorbornene, etc. (1) and 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 monomer (1) and the monomer (2) to the other copolymerizable monomer is [monomer (1) + monomer (2)]: [other copolymerizability] The monomer] is preferably 100: 0 to 50:50 by weight, more preferably 100: 0 to 60:40, and still more preferably 100: 0 to 70:30.

<Ring-opening polymerization catalyst>
The ring-opening polymerization reaction of the specific monomer is 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 (for example, Li, Na, K) of the periodic table. 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 at least one compound selected from those having at least one element-carbon bond or the element-hydrogen bond (hereinafter referred to as a compound of a Group 14 element (for example, Si, Sn, Pb, etc.)). And “(b) component”), and may contain an additive (hereinafter referred to as “(c) component”) in order to enhance the catalytic activity. There.

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), n-C 4 H 9 Li} , (C 2 H 5) 3 Al, (C 2 H 5) 2 AlCl, (C 2 H 5) 1.5 Examples include compounds described in JP-A-1-240517 such as AlCl _1.5 , (C ₂ H ₅ ) AlCl ₂ , methylaluminoxane, and LiH.
As the component (c), alcohols, aldehydes, ketones, amines and the like can be preferably used, but other compounds shown in JP-A-1-240517 can be used.
In addition, as a metathesis catalyst other than the components (a), (b), and (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, still more preferably 97% or more, particularly preferably 99% or more. It is.
The cyclic olefin resin used in the present invention preferably has an intrinsic viscosity (η _inh ) measured in chloroform at 30 ° C. of 0.2 to 5.0 dl / g.
The average molecular weight of the cyclic olefin resin is 8,000 to 100,000 in terms of polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC), and 20,200 in weight average molecular weight (Mw). The thing of the range of 000-300,000 is suitable.
Furthermore, the glass transition temperature of the cyclic olefin-based resin is preferably 100 to 250 ° C., more preferably 110 to 180 ° C., in order to ensure thermal stability, moldability in the case of extrusion film formation, and adhesion between layers in lamination. More preferably, it is 120-170 degreeC. The cyclic olefin-based resin used in the present invention 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 The vinyl aromatic resin used in the present invention has a repeating unit (6) represented by the following formula (6).

[In the formula (6), R ¹⁰ represents a hydrogen atom or a methyl group. R ^{11 to} R ¹³ 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 oxygen, nitrogen, sulfur or silicon; or Represents a polar group. ]

  Specific examples of the monomer for deriving the repeating unit (6) 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 is particularly excellent in adhesion to the cyclic olefin resin, has a high glass transition temperature, and easily develops the desired optical characteristics, together with the repeating unit (6), the following formula (7 It is preferable to have a repeating unit (7) represented by formula (8) and / or a repeating unit (8) represented by the following formula (8). When the repeating unit (7) is included, the resulting laminated optical film has excellent surface smoothness. When the repeating unit (8) is included, there is an advantage that the resin is hardly deteriorated by heat during processing.

[In the formula (7), X represents an oxygen atom or a nitrogen atom having a substituent. In the formula (8), R ¹⁴ represents a hydrogen atom or a methyl group, and R ¹⁵ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. 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. Group and the like. ]

  The vinyl aromatic resin may have a structure containing both the repeating unit (7) and the repeating unit (8) together with the repeating unit (6), and either the repeating unit (7) or the repeating unit (8). A structure including only Further, the acid anhydride structure or imide structure of the repeating unit (7) may be hydrolyzed to a dicarboxylic acid structure or an amic acid structure.

Specific examples of the monomer for deriving the repeating unit (7) include N-substituted maleimides such as maleic anhydride, maleimide and N-phenylmaleimide, maleic acid and derivatives thereof, fumaric acid and derivatives thereof, and the like. Any of these monomers may be used alone or in combination of two or more. Of these monomers, maleic anhydride and N-phenylmaleimide are preferably used in terms of heat resistance and adhesion to the cyclic olefin resin layer.
Specific examples of the monomer for inducing the repeating unit (8) include (meth) acrylic acid, (meth) acrylic acid alkyl esters such as methyl (meth) acrylate, and (meth) acrylic amide. 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-based resin layer.
From the above, styrene- (meth) acrylic acid copolymer and styrene-maleic anhydride copolymer are particularly preferable as the vinyl aromatic resin.

In the present invention, the use ratio of the repeating unit (6) to the repeating unit (7) and / or the repeating unit (8) in the vinyl aromatic resin is usually the repeating unit (6): [repeat unit] in weight ratio. (7) + Repeating unit (8)] = 100: 0 to 50:50, preferably 98: 2 to 60:40, more preferably 95: 5 to 70:30. Adjustment of glass transition temperature, adjustment of phase difference, adjustment of moldability in extrusion film formation, securing of stretch processability, and adhesion with cyclic olefin resin layer due to use ratio being in the above range Is possible.
In addition to the repeating unit (7) and the repeating unit (8), vinyl aromatic resins include ethylene, propylene, butene, butadiene, isoprene, (meth) acrylonitrile, α-chloroacrylonitrile, acetic acid as necessary. Other monomers such as vinyl, vinyl chloride and itaconic anhydride may also be included as a copolymerization component.

The vinyl aromatic resin used in the present invention has a logarithmic viscosity (η _inh ) measured in a chlorobenzene solution (concentration 0.5 g / dL) at 30 ° C. of 0.1 to 3.0 dL / g. preferable. 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. When the molecular weight is too large, the solution viscosity and the melt viscosity become too high, and the productivity and workability of the vinyl aromatic resin film used in the present invention may be deteriorated.
The molecular weight distribution (Mw / Mn) of the vinyl aromatic resin is usually 1.0 to 10, preferably 1.2 to 5.0, and more preferably 1.2 to 4.0.

The vinyl aromatic resin used in the present invention comprises the above-mentioned monomers for deriving the repeating unit (6) and, if necessary, the repeating unit (7) and / or the repeating unit (8), as a suitable polymerization initiator. It is preferable to manufacture by the method of making it superpose | polymerize in presence of this. 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 vinyl aromatic 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 -Ethyl hexanoate, t-butyl peroxyisobutyrate, t-butyl peroxy maleate, t-butyl peroxy 3,5,5-trimethyl hexanoate, t-butyl peroxy laurate, 2,5 -Dimethyl-2,5-bis (m-toluoylperoxy) hexane, α, α'-bis (neodecanoylpa Oxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylper Oxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxybenzoate, t-hexylperoxybenzoate, bis (t-butylperoxy) isophthalate, 2,5-dimethyl-2,5 -Peroxyesters such as bis (benzoylperoxy) hexane, t-butylperoxy m-toluoylbenzoate, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) 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, 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.

  As the azobis radical polymerization initiator, azobisisobutyronitrile, azobisisovaleronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2 , 4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2- (carbamoylazo) isobutyronitrile, , 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- ( -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] dihydrochloride, 2 , 2'-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2'-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane ] Dihydrochloride, 2,2'-azobis [2- {1- (2-hydroxyethyl) -2-imidazolin-2-yl} propane] dihydrochloride Id, 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-cyanopenta) Noic acid), 2,2′-azobis (2,4,4-trimethylpentane), etc., but the azobis radical polymerization initiator used in the present invention is not limited to these exemplified compounds. .

  These radical initiators are used in an amount of generally 0.01 to 5 mol%, preferably 0.03 to 3 mol%, more preferably 0.05 to 2 mol, based on 100 mol% of the total amount of monomers for inducing the vinyl aromatic resin. %.

Furthermore, a catalyst may be used in the polymerization reaction of the monomer for inducing the vinyl aromatic resin. This catalyst is not particularly limited, and examples thereof include known anionic polymerization catalysts, coordination polymerization catalysts, and cationic polymerization catalysts.
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 is preferably 110 to 200 ° C. in order to ensure thermal stability, moldability in the case of extrusion film formation, stretch workability, and adhesion between layers in lamination. Preferably it is 120-170 degreeC. In the present invention, it is preferable that the glass transition temperature (TgA) and TgB of the cyclic olefin-based resin satisfy the following formula (iv).
| TgA−TgB | ≦ 20 (° C.) (iv)
The value of the above formula (iv) is more preferably | TgA-TgB | ≦ 15 (° C.), more preferably | TgA-TgB | ≦ 12 (° C.), particularly preferably | TgA-TgB | ≦ 10 (° C.). It is. By setting the glass transition temperature in the above range, the retardation of each of the cyclic olefin resin and the vinyl aromatic resin can be controlled simultaneously by stretching, and the desired characteristics of the laminated optical film (formula (i), formula (Ii), the characteristics represented by formula (iii) and formula (v), etc.) can be easily obtained.

The vinyl aromatic resin used in the present invention includes, as necessary, an antioxidant, a heat stabilizer, a light stabilizer, a phase difference adjusting agent, an ultraviolet absorber, an antistatic agent, a dispersant, a processability improver, Chlorine scavenger, flame retardant, crystallization nucleating agent, anti-blocking agent, anti-fogging agent, mold release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, contamination prevention Known additives such as 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. .

Production method of film (A) and film (B) The film (A) and the film (B) used for the production of the raw film use a cyclic olefin resin and a vinyl aromatic resin, respectively. Any of the films (B) can be obtained by forming a film by a known method such as a melt extrusion method or a solution casting method.
Since the film (A) is made of a cyclic olefin resin, the film (A) is excellent in balance in optical properties such as transparency, chemical resistance, heat resistance, water resistance and moisture resistance. The film (A) has a film thickness of 20 to 200 μm, preferably 50 to 180 μm, and a film thickness variation (difference between the maximum thickness and the minimum thickness) within 4 μm, preferably within 3 μm, more preferably within 2 μm. is there. If the thickness unevenness exceeds 4 μm, the optical characteristics are uneven depending on the location, and the display quality such as the contrast ratio and color shift of the liquid crystal display device incorporating this film may be uneven depending on the location.
The film (B) is made of a vinyl aromatic resin, and has an effect that the obtained laminated optical film satisfies the characteristics represented by the above formula (i). The film (B) has a film thickness of 20 to 200 μm, preferably 50 to 150 μm, and the film thickness unevenness (difference between the maximum thickness and the minimum thickness) is within 4 μm, preferably within 3 μm, more preferably within 2 μm. is there. If the thickness variation exceeds 4 μm, the optical characteristics are non-uniform depending on the location, and the display quality such as contrast ratio and color shift of the liquid crystal display device incorporating this film may be non-uniform depending on the location.

Therefore, die lines that cause variations in thickness (longitudinal streaks caused by T-die lip scratches during melt extrusion), cross marks (periodic thickness fluctuations in the length direction), wind ripples (solutions) It is desirable that the thickness variation) caused by drying unevenness during casting is small.
Further, it is desirable that there are few gels, foreign matters, dents and the like that cause display defects such as bright spots and light leaks as point-like defects. For example, in the case of the melt extrusion method, 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, transfer roll, peeling roll, transport roll Can be suppressed by smoothing, surface treatment, and the like. In the case of the solution casting method, filtration with a resin solution filter, reduction of gear pump pulsation, die lip polishing and surface treatment, optimization of drying conditions, transfer roll, transfer belt, release roll, smoothing of transport roll, surface treatment Or the like.

Lamination process The specific method for laminating the film (A) made of a cyclic olefin resin and the film (B) made of a vinyl aromatic resin is not particularly limited, and the film ( A) and the film (B) may be fixed as long as they can be relatively fixed. Preferably, (1) a plurality of films are transported and passed between pinch rolls, so that a plurality of sheets The method of crimping | bonding a film is mentioned. Among these methods, as a more preferable method,
(2) In the method of (1), a method of pressure bonding a plurality of films under heating (3) In the method of (1), a solvent that dissolves both the cyclic olefin resin and the vinyl aromatic resin, For example, one or more of methylene chloride, chloroform, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, cyclohexanone, etc. are sprayed onto the film surface, and the film surface is melted and pressed. And then drying the solvent. However, in any method, the films (A) and (B) in a state of being wound into a roll shape are continuously laminated to each other, and the laminated film is wound up as an original film roll. Is preferable in terms of productivity. In addition, it is also preferable to improve productivity by continuously forming the film (A) and / or the film (B) and laminating, and continuously performing lamination and stretching. In the present invention, the method (2) is particularly preferably used in order to easily obtain adhesion between the film (A) and the film (B).
At this time, the heating temperature is preferably TgA or more and TgB or more, more preferably TgA + 10 ° C. or more and TgB + 10 ° C. or more. If the temperature is too high, the film may be in a molten state and cannot be conveyed, so the upper limit temperature is appropriately selected according to the melt viscosity of the resin. The heating method is not particularly limited, and the film may be heated by transporting the inside of the roll on a heated roll, or the film is heated by passing through a heating furnace provided with a heater or the like. May be.

Since film (A) and film (B) have good thermal adhesion, they can be laminated in direct contact with each other, and surface treatment of the laminated surface is not necessary. Various adhesives, plasma treatment, corona treatment, and the like may be applied.
It is preferable to use one film (A) and one film (B) each because it is excellent in productivity in the laminating process, optical characteristics (transparency), and retardation controllability in the stretching process, but a total of 3 or more layers The film may be laminated. A laminated optical film composed of three or more layers is preferable for securing the necessary thickness and retardation and obtaining the mechanical strength of the film.
In order to prevent adhesion of the molten film to the pinch roll during lamination, the film (A) and the film (B) may be sandwiched between transfer base films. The substrate film for transfer is preferably heat-resistant and has a good peelability for the original film produced by lamination, such as PET, polyimide, polyamideimide, polysulfone, polyphenylene sulfide, polyetherimide, polyethersulfone, etc. Is used. These transfer base films are preferably subjected to a release treatment.

  It is desirable that the obtained raw film has a uniform thickness in both the width direction and the length direction. The thickness variation causes a phase difference variation of the laminated optical film obtained after stretching, and impairs the uniformity of display when it is incorporated in a liquid crystal display device. The total thickness variation (difference between the maximum thickness and the minimum thickness) of the raw film is preferably within 7 μm, more preferably within 5 μm, and even more preferably within 4 μm.

The laminated optical film of the present invention having a function as a stretching step retardation film can be produced by stretching the raw film. Conventionally known methods can be applied to the method of stretching the laminated optical film, but uniaxial stretching is preferably used in the direction perpendicular to the film longitudinal direction, that is, in the width direction. Specifically, a method of uniaxially stretching in the width direction using a tenter is preferable. By doing so, the excellent phase difference characteristics of the present invention can be expressed.

In the stretching process in the production method of the present invention, it is preferable to determine the stretching temperature based on TgA and TgB in order to adjust the phase difference. Specifically, (the lower value of TgA and TgB) −10 (° C.) to (the higher value of TgA and TgB) +30 (° C.), preferably (the lower value of TgA and TgB) Value) −5 (° C.) to (the higher value of TgA and TgB) +20 (° C.).
By setting the stretching temperature in the above range, the retardation of each of the film (A) layer and the film (B) layer can be controlled simultaneously by stretching, and the desired properties of the laminated optical film (formula (i), formula (1)) (Ii), the characteristics represented by formula (iii) and formula (v), etc.) can be easily obtained. Accordingly, a liquid crystal display device having a high contrast ratio and a small color shift when the screen is viewed from an oblique direction can be realized.

  In the production method of the present invention, the draw ratio is usually 1.1 to 10 times, preferably 1.2 to 7 times, and more preferably 1.3 to 5 times. In particular, the film is suitably stretched 1.3 to 5 times by lateral uniaxial stretching that is uniaxially stretched in a direction orthogonal to the film longitudinal direction. Since the laminated optical film of the present invention is stretched uniaxially in the horizontal direction, the optical axis (in-plane maximum refractive index direction) becomes a direction (film width direction) perpendicular to the film longitudinal direction. Can be bonded by roll-to-roll, improving productivity.

[Laminated optical film]
The laminated optical film of the present invention is preferably formed by laminating the A layer and the B layer in direct contact with each other.
The length of the laminated optical film in the longitudinal direction 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 1000 mm or more, more preferably 1500 mm or more, and particularly preferably 2000 mm or more.
The laminated optical film of the present invention is not particularly limited, but the film thickness is usually 10 to 200 μm, preferably 20 to 170 μm, and particularly preferably 30 to 150 μm. This is desirable for adjustment.
Further, it is preferable that the thickness variation is small since the variation of the retardation value is small and the display quality is uniform. The range of thickness variation of the laminated optical film is within an average value ± 5%, preferably within an average value ± 3%, and more preferably within an average value ± 2%.
In addition, the laminated optical film of the present invention may be an unstretched film or a stretched film, but is stretched to satisfy the characteristics described in the formulas (i) to (iii) and the formula (v). It is preferable that it is a film.
The laminated optical film of the present invention is particularly preferably formed by the method for producing a laminated optical film of the present invention.

Optical properties of laminated optical film The laminated optical film of the present invention is characterized in that the measured values of retardation as the laminated optical film satisfy all the properties of the following formulas (i) to (iii).
R450 <R550 <R650 (i)
1.0 <R650 / R550 <1.2 (ii)
70 nm ≦ R550 ≦ 150 nm (iii)
[In the above formulas (i) to (iii), R450, R550, and R650 represent the in-plane retardation of the laminated optical film at wavelengths of 450 nm, 550 nm, and 650 nm, respectively. ]

  The above (i) and (ii) indicate the wavelength dispersion of the phase difference, and the above (i) indicates that the longer the wavelength, the larger the in-plane phase difference, the so-called reverse wavelength dispersion. . This is a characteristic necessary for preventing the polarization state of the light passing through the laminated optical film from being different depending on the wavelength and reducing the color shift amount when the screen is viewed from an oblique direction. The value of (ii) above represents the degree of inverse wavelength dispersion. In order to reduce the amount of color shift and perform good viewing angle compensation, a larger value is desirable, preferably 1.01 to 1.18, more preferably 1.02 to 1.18. The above (iii) shows the amount of retardation in the film plane. As a retardation film for a VA mode liquid crystal display device, a compensation method combining an A plate and a C plate is known to be effective. At this time, an in-plane retardation that effectively functions as an A plate is shown in (iii). In the range shown, it is preferably 75 nm to 145 nm, more preferably 75 nm to 140 nm. Satisfying the above (iii) provides a good contrast ratio. In addition, satisfying the above (i) and (ii) can reduce the color shift and further improve the contrast ratio when observed from an oblique direction. Also contributes.

Further, in order to obtain display quality uniformity, it is desirable that there is less variation in phase difference depending on the location in both the width direction and the longitudinal direction of the film. The range of variation of R650 / R550 in (ii) is preferably within ± 0.03, more preferably within ± 0.02, and particularly preferably within ± 0.01. The range of the variation of R550 in the above (iii) is preferably within ± 6 nm, more preferably within ± 4 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. When the film width direction orthogonal to the film longitudinal direction is used as a reference, it is preferably within ± 1 °, more preferably ± It is within 0.8 °, more preferably within ± 0.6 °, and particularly preferably within ± 0.5 °.

Moreover, it is preferable that the laminated optical film of this invention satisfy | fills following formula (v).
1.0 ≦ NZ ≦ 3.0 (v)
[In the above formula (v), NZ is a coefficient represented by NZ = (nx−nz) / (nx−ny)]. Here, nx represents the maximum refractive index in the laminated optical film plane, ny represents the refractive index in the laminated optical film plane in the direction orthogonal to the maximum refractive index direction, and nz represents the refractive index in the laminated optical film thickness direction. These are all values at a wavelength of 550 nm. ]

  The above (v) is a numerical value called an NZ coefficient, and is a numerical value representing the balance between the in-plane retardation and the thickness direction retardation of the laminated optical film. 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 the film average By calculating numerically using the refractive index, nx, ny, and nz are obtained, and determined as NZ = (nx−nz) / (nx−ny).

Specifically, the NZ coefficient is obtained as follows. For example, for a single-layer film, the in-plane retardation at a wavelength of 550 nm is R0 (nm), the oblique retardation at a wavelength of 550 nm measured from a polar angle of 40 degrees with a slow axis tilt is R40, and the wavelength at 550 nm is When the average refractive index Nave and the thickness are d (nm), the following equations (vi) to (ix) are established.
R0 = (nx−ny) × d (vi)
R40 = (nx−ny ′) × (d / cos 40 °) (vii)
Nave = (nx + ny + nz) / 3 (viii)
(Ny ′ × sin 40 ° / ny) ² + (ny ′ × cos 40 ° / nz) ² = 1 (ix)
nx is the maximum refractive index in the laminated optical film plane, ny is the refractive index in the laminated optical film plane in the direction orthogonal to the maximum refractive index direction, and nz is the refractive index in the thickness direction orthogonal to nx and ny. It is. ny ′ is the “apparent ny” when measured from the polar angle of 40 degrees with the slow axis tilt, and the direction orthogonal to the apparent maximum refractive index (because it is the slow axis tilt, the value is equal to nx). Is the refractive index. (Vi) and (viii) are as defined in general, and (vii) represents R40 using the apparent refractive index. (Ix) represents ny ′ using an ellipse expression representing the yz section of the refractive index ellipsoid. Since R0, R40, Nave, and d are known as measured values, and there are four unknowns, nx, ny, nz, and ny ', four equations can be solved for four variables, and an NZ coefficient is obtained. . However, in the case of the laminated optical film of the present invention, since the average refractive indexes of the A layer and the B layer are different, Nave cannot be directly measured and determined.

  Therefore, in the present invention, for convenience, the average refractive index Nave of the laminated optical film is a value obtained by weighted average 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) / (dA + dB) And Since d (nm) = dA (nm) + dB (nm), nx, ny, and nz are numerically calculated as described above to determine NZ.

The thicknesses dA and dB of each layer are measured by peeling each layer and measuring the thickness of each layer with a contact micrometer, or observing a cross section of the laminated optical film with a microscope, or a known non-contact measurement method such as an optical interference method. It is measured using a 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.
In addition, when there are two or more A layers and / or B layers, respectively, for example, in the case of a three-layer configuration of A layer / B layer / A layer, dA is a value obtained by adding the thicknesses of two or more A layers, dB is the sum of the thicknesses of two or more B layers.
The NZ coefficient closer to 1 is closer to the positive A plate, which is preferable because it matches the compensation method combining the A plate and the C plate, which is a compensation method for the VA liquid crystal, and the contrast ratio is improved. Preferably it is 1.0-2.5, More preferably, it is 1.0-2.0. A film having an NZ coefficient of less than 1 does not have reverse wavelength dispersion.
In order to obtain display quality uniformity, it is desirable that there is less variation in NZ depending on the 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.

The photoelastic coefficient of the laminated optical film of the present invention is due to the stress at the time of being incorporated in a liquid crystal display device, a decrease in contrast ratio due to light leakage at the periphery called a frame failure, or a display failure when the user touches the display surface To prevent this, a smaller one is desirable. In addition, as the liquid crystal display device is increased in size and definition, an optical film having a smaller photoelastic coefficient is required. Therefore, it is preferably 20 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 15 × 10 ⁻¹² Pa ⁻¹ or less, and even more preferably 10 × 10 ⁻¹² Pa ⁻¹ or less. The laminated optical film of the present invention can suppress the photoelastic coefficient to 10 × 10 ⁻¹² Pa ⁻¹ or less, and can be suitably used for various applications.

Optical characteristics (phase difference) of each layer
The A layer and the B layer constituting the laminated optical film of the present invention have desirable retardation values and retardation wavelength dispersion properties, respectively. However, since it is impossible to measure the phase difference of each of the A layer and the B layer 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, or the A layer and the B layer are separated. Calculate the retardation value of the A layer and the B layer from the retardation wavelength dispersion of each of the constituting polymers and the retardation wavelength dispersion of the laminated optical film, or laminate the optical film of only the A layer and the film of only the B layer. By stretching under the same conditions as the film and measuring the retardation separately, the characteristics of each layer can be confirmed. When the in-plane retardation of the A layer at wavelengths of 450 nm and 550 nm is R450A and R550A, and the in-plane retardation of the B layer at wavelengths of 450 nm and 550 nm is R450B and R550B, each layer satisfies the following conditions (x) to (xiv). It is adjusted as follows.
R450A / R550A ≦ 1.04 (x)
200 nm ≦ R550A ≦ 400 nm (xi)
1.04 <R450B / R550B (xii)
100 nm ≦ R550B ≦ 300 nm (xiii)
R550A> R550B (xiv)

  The A layer and the B layer satisfy the above formulas (x) to (xiv), thereby satisfying the above formulas (i) to (iii) as a laminated optical film, and the color shift when the liquid crystal display device is viewed from an oblique direction. At the same time, the contrast ratio can be improved. In addition, since A layer and B layer differ in the positive / negative of intrinsic birefringence, when A layer and B layer are extended | stretched simultaneously as a laminated optical film, the maximum refractive index direction of A layer and B layer is mutually orthogonal. For this reason, the in-plane retardations cancel each other, and the in-plane retardation R550 of the laminated optical film is represented by R550A-R550B. From the above formula (xiv), the optical axis of the laminated optical film becomes a direction orthogonal to the film longitudinal direction, and roll-to-roll adhesion with the polarizer becomes possible, thereby improving the productivity of the polarizing plate.

  By using the method for producing a laminated optical film of the present invention and stretching in the film width direction at the above-mentioned stretching temperature and stretch ratio, each layer can satisfy the above (x) to (xiv) by one stretching process. At the same time, the above laminated optical film can satisfy the above (i) to (iii). For this reason, the manufacturing method of the laminated optical film of this invention is very excellent in productivity.

The above (x) and (xii) represent the wavelength dispersion of the retardation of each layer. R450A / R550A of the A layer is smaller than R450B / R550B of the B layer, and the chromatic dispersion of the A layer is flat chromatic dispersion that does not change much for each wavelength, or inverse chromatic dispersion in which the phase difference increases as the wavelength increases. is there. On the other hand, the wavelength dispersion of the B layer is so-called positive wavelength dispersion in which the phase difference decreases as the wavelength increases compared to the A layer. When the A layer and the B layer satisfy this characteristic, the laminated optical film satisfies the characteristics of the above formulas (i) and (ii) when the phase difference is canceled between the A layer and the B layer.
When there are two or more A layers and / or B layers, for example, in the case of a three-layer configuration of A layer / B layer / A layer, R450A and R550A add up the phase difference of two or more A layers. R450B and R550B are values obtained by summing the phase differences of two or more B layers.

In addition, it is desirable for the A layer and the B layer that there is little variation in retardation depending on the location in order to obtain display quality uniformity. The range of variation of (x) and (xii) is preferably within ± 0.03, more preferably within ± 0.02, and particularly preferably within ± 0.01. The range of variation of R550A and R550B represented by (xi) and (xiii) is preferably within ± 5 nm, more preferably within ± 4 nm, and particularly preferably within ± 3 nm.
Also, it is desirable that the optical axis variation of each layer is small depending on the location in order to obtain display quality uniformity. The optical axis of the A layer is preferably within ± 1 degree, more preferably within ± 0.8 degree, further preferably within ± 0.6 degree, and particularly preferably ± 0.5 degree with respect to the film width direction. Is within. The optical axis of the B layer is preferably within ± 1 degree, more preferably within ± 0.8 degree, further preferably within ± 0.6 degree, and particularly preferably ± 0.5 degree with respect to the film longitudinal direction. Is within.

In addition, in order to obtain display quality uniformity, it is desirable that the thickness variation depending on the location of both the A layer and the B layer is small because the variation of the phase difference is small. The variation ranges of dA and dB are each within an average value ± 5%, preferably within an average value ± 3%, and more preferably within an average value ± 2%, similarly to the range of thickness variation of the entire laminated optical film.
The thickness ratio of 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. However, in order to control the phase difference, specifically, a single transverse stretching process is performed. In order to develop a predetermined retardation, the thickness ratio of the A layer is preferably 20 to 90%, more preferably 30 to 80%, and further preferably 40 to 80% of the entire laminated optical film. (When there are two or more A layers and / or B layers, the thicknesses of the respective layers are summed up and expressed as a thickness ratio of the entire laminated optical film of all A layers)

  Furthermore, in order for the NZ coefficient of the laminated optical film of the present invention to satisfy the above formula (v), the A layer and the B layer constituting the laminated optical film each have a desirable NZ coefficient range. 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 separately measured to obtain the NZ coefficient, or only the A layer is obtained. The film and the film of only the B layer are stretched under the same conditions as the laminated optical film, and the phase difference is separately measured to obtain the approximate NZ coefficient of each layer. When the NZ coefficient of the A layer is NZA and the NZ coefficient of the B layer is NZB, the following conditions (xv) to (xvi) are satisfied.

1.0 ≦ NZA ≦ 1.7 (xv)
−1.0 ≦ NZB ≦ 0 (xvi)
[In the above formula (xv), NZA is a coefficient represented by NZA = (nxA−nzA) / (nxA−nyA), and is a value at a wavelength of 550 nm. Here, nxA is the maximum refractive index in the plane of the A layer, nyA is the refractive index in the direction orthogonal to nxA in the plane of the A layer, and nzA is the refractive index in the thickness direction of the A layer orthogonal to nxA and nyA. The rate is expressed as NaveA = (nxA + nyA + nzA) / 3. In the above formula (xvi), 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 B layer, nyB is the refractive index in the direction orthogonal to nyB in the plane of the B layer, and nzB is the refractive index in the thickness direction of the B layer orthogonal to nxB and nyB. The rate is expressed as NaveB = (nxB + nyB + nzB) / 3. ]

The above formula (xv) corresponds to a phase difference developed when the cyclic olefin resin layer is laterally stretched, where nxA is the stretching direction, ie, the film width direction, and nyA is perpendicular to the stretching direction, ie, the film longitudinal direction. In the refractive index ellipsoid, it is generally called a positive A plate. The above formula (xvi) corresponds to a phase difference developed when the vinyl aromatic resin layer is laterally stretched. NxB is orthogonal to the stretching direction, that is, the film longitudinal direction, and nyB is the stretching direction, that is, the film width direction. In the refractive index ellipsoid, it is generally called a negative A plate. The NZ of the laminated optical film cannot be obtained by simple calculation from NZA and NZB, and is related as a result of the change in the polarization state in the A layer and the change in the polarization state in the B layer by Poincare sphere display.

NZA and NZB have a desirable range, preferably (NZA + NZB) /2=0.1 to 0.8, more preferably (NZA + NZB) /2=0.2 to 0.8, more preferably ( NZA + NZB) /2=0.3 to 0.7. When NZA and NZB satisfy this range, the laminated optical film exhibits reverse wavelength dispersion when viewed from any direction, and a predetermined phase difference cannot be obtained due to the optical axis shift of each layer when viewed from any direction. No problem occurs, leading to improved panel characteristics due to reduced color shift. A smaller NZA leads to improved panel characteristics, and is preferably 1.0 to 1.6, more preferably 1.0 to 1.5. At the same time, a larger NZB leads to improved panel characteristics, preferably -0.6 to 0, more preferably -0.5 to 0. By setting the NZ coefficient of each layer in the above range, it is possible to have a predetermined phase difference even when observed from an oblique direction, to reduce the color shift at an oblique viewing angle of the liquid crystal display device, and simultaneously improve the contrast ratio. Is possible.
Further, in order to obtain uniformity in display quality, it is desirable that both NZA and NZB have less variation depending on the 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.

[Polarizer]
The polarizing plate of the present invention has the laminated optical film of the present invention having a function as a retardation film on at least one surface, and the laminated optical film of the present invention is laminated on at least one surface of a polarizer (polarizing film). It is desirable to have the configuration described above. As a polarizer constituting the polarizing plate of the present invention, for example, a film made of polyvinyl alcohol (PVA) or a polymer obtained by formalizing a part of PVA, etc., and a dichroic substance made of iodine or a dichroic dye are used. A film obtained by performing a dyeing process, a stretching process, a crosslinking process, and the like in an appropriate order and method, and transmits linearly polarized light when natural light is incident thereon. In particular, those having a high light transmittance and an excellent degree of polarization are preferably used.

  The thickness of the polarizer constituting the polarizing plate is generally preferably 5 to 80 μm, but the present invention is not limited to this. Moreover, as a polarizer, you may use another thing other than the said PVA-type film, if the same characteristic is expressed. 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, but in the present invention, as a retardation film that constitutes a polarizing plate, a laminated optical film is bonded to at least one surface of the polarizer. Or it bonds and uses through an adhesive. The laminated optical film may be bonded to the polarizer on the A layer side, or may be bonded to the polarizer on the B layer side. In such a polarizing plate, the retardation film is excellent in properties such as heat resistance, moisture resistance and chemical resistance 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, triacetyl. A known protective film such as cellulose (TAC), a cyclic olefin resin film, or an acrylic resin film 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 layer using a known adhesive or pressure sensitive adhesive such as a pressure sensitive adhesive, a thermosetting adhesive, or a photocurable adhesive. It can manufacture suitably by adhering via. 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 obtained by adding a curing agent such as an isocyanate group-containing compound to the 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.

In addition, the polarizing plate of the present invention preferably further includes at least one layer selected from an antireflection layer and an antiglare layer, and is preferably provided outside the protective film surface on the side opposite to the polarizer.
These layers are formed by applying a thermosetting resin composition or a photocurable resin composition by a known coating method such as gravure coating, die coating, or slot coating, drying as necessary, and then curing. can do. These layers may be provided directly on the protective film, or may be formed by providing a base film on the protective film and bonding the base film to the protective film. Moreover, the said layer may be formed before bonding a protective film or a base film to a polarizer, and the said layer may be formed after bonding to a polarizer.

  The antireflection layer is usually composed of a low refractive index layer, and may further have a laminated structure of a low refractive index layer and a high refractive index layer to further improve the antireflection performance, and further ensure scratch resistance. Therefore, you may have a hard-coat layer. The lamination order is preferably from the side close to the protective film, preferably in the order of hard coat layer / high refractive index layer / low refractive index layer. If necessary, an intermediate refractive index layer may be provided between the low refractive index layer and the high refractive index layer, or between the hard coat layer and the high refractive index layer. These layers can be formed by sputtering, vapor deposition, or the like, but are preferably formed by applying the curable composition as described above.

Examples of the composition for forming the low refractive index layer and the high refractive index layer include known curable compositions. For example, the binder resin contains at least one epoxy resin, phenol resin, melamine resin, alkyd resin, cyanate resin, acrylic resin, polyester resin, urethane resin, siloxane resin, and the like, The composition for forming a low refractive index layer contains a fluorine-containing compound, and the composition for forming a high refractive index layer is a high refractive index inorganic particle, for example, a metal such as silica, alumina, titania, zirconia, ceria, scandia, magnesium fluoride, etc. Contains oxide particles.
The refractive index and thickness of the low refractive index layer and the high refractive index layer are used within a known range, but in order to enhance the antireflection effect, the refractive index of the low refractive index layer (average refractive index at 25 ° C. and wavelength 589 nm) is 1.45 or less, and the thickness of the low refractive index layer is preferably 50 to 300 nm. The refractive index of the high refractive index layer (average refractive index at 25 ° C. and wavelength 589 nm) is preferably a refractive index larger by 0.05 or more than the refractive index of the low refractive index layer, and the thickness is 50 to 10, 000 nm is preferable.

A known material can be used as a constituent material of the hard coat layer. Examples of such a material include one or more of a siloxane resin, an acrylic resin, a melamine resin, an epoxy resin, and the like, and inorganic particles such as a metal oxide may be included. The hard coat layer may have an effect as an antiglare layer described later.
The thickness of the hard coat layer is not particularly limited, but is preferably 2 to 10 μm.

  As the antiglare layer, a layer that exhibits antiglare properties by having irregularities on the layer surface is usually used, and a layer having a surface centerline average roughness of 0.1 to 1.0 μm is preferable. As the composition for forming the antiglare layer, a curable composition containing organic particles and / or inorganic particles is preferably used. As the binder resin used for the curable composition, the binder resin of the curable composition used for forming the antireflection film described above can be used. As preferable anti-glare properties, the layer has a Haze of 5 to 65% and a total light transmittance of 80 to 98%.

[Liquid Crystal Display]
The liquid crystal display device of the present invention is characterized by having the polarizing plate of the present invention. The liquid crystal display device of the present invention has a high contrast ratio when the screen is viewed from an oblique direction, a small color shift amount when the screen is viewed from an oblique direction, and a laminated optical film having a small thickness unevenness and optical unevenness. Since it has a polarizing plate, it is possible to display uniformly, and since the glass transition temperature of the resin contained in the laminated optical film is high and has heat resistance, it has excellent durability to withstand long-term use in harsh environments. .

  The laminated optical film and polarizing plate according to the present invention can be used for various optical components. For example, various liquid crystal display devices such as liquid crystal televisions, liquid crystal monitors, mobile phones, car navigation systems, portable game machines, digital information terminals, liquid crystal projectors, electroluminescent display elements or transparent conductive films such as ITO are used for touch panels and the like. be able to. It is also useful as a wave plate used in the optical system of optical disc recording / reproducing devices, a near-infrared cut film used in an optical system such as a camera, a circularly polarizing plate or an elliptically polarizing plate for antireflection or optical elements. It is.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. In the following Examples and Comparative Examples, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified. Moreover, room temperature is 25 degreeC.
In the following examples and comparative examples, 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 reaction rate was determined from the ratio to 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. The hydrogenation rate was calculated after calculating the monomer composition from the integral value of 5.1 to 5.8 ppm of vinylene group, 3.7 ppm of methoxy group, and 0.6 to 2.8 ppm of aliphatic proton.

[Glass transition temperature (Tg)]
Using a differential scanning calorimeter (manufactured by Seiko Instruments Inc., trade name: DSC6200), the temperature was measured at a temperature increase rate of 20 ° C./min in accordance with Japanese Industrial Standard 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 , 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. The Mn is a number average molecular weight.

[Logarithmic viscosity]
Using an Ubbelohde viscometer, the logarithmic viscosity was measured at a sample concentration of 0.5 g / dL and a temperature of 30 ° C. in chlorobenzene.
`` Residual solvent amount ''
The film to be measured was cut into 5 cm square, and the weight X of the laminated optical film before heating and the weight Y of the laminated optical film after heating at 200 ° C. for 30 minutes were measured, and the residual solvent amount was calculated by the following formula .
Residual solvent amount (% by weight) = [(XY) / X] × 100

[Thickness of each layer]
The monolayer film before lamination was measured with a Digimatic indicator (micrometer) manufactured by Mitutoyo Corporation.
The laminated optical film was flattened by cutting a cross section, and the thickness of each layer was measured by observation with an optical microscope. If 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. did.
[Thickness variation of raw film]
The total width in the film width direction was measured at 10 points at regular intervals (this is assumed to be one row measurement), and two rows were measured to determine thickness variation. Further, the interval between the rows was separated by 30 cm or more.

[Phase difference]
It measured using the automatic birefringence meter (The Oji Scientific Instruments Co., Ltd. make, KOBRA-21ADH). The in-plane retardations R450, R550, and R650 at wavelengths of 450 nm, 550 nm, and 650 nm are obtained by regression calculation of measured values at wavelengths of 478.8 nm, 546.0 nm, 629.3 nm, and 747.3 nm using Cauchy's equation. It was. The NZ coefficient was determined from the in-plane retardation of the film and the slow axis inclination, the oblique retardation from a polar angle of 40 degrees, the film thickness, and the film average refractive index.
[Phase difference of laminated optical film]
The total width in the film width direction was measured at 10 points at regular intervals (this is assumed to be one-row measurement), and two rows were measured to determine phase difference variation. Further, the interval between the rows was separated by 30 cm or more.

[Single transmittance, degree of polarization]
The single transmittance and polarization degree of the polarizing plate were measured using V-7300 manufactured by JASCO Corporation.
[Measurement of liquid crystal display device characteristics]
Using an “EZ contrast-XL88” manufactured by ELDIM, the luminance contrast ratio and the color shift of the liquid crystal display device were measured in a dark room having an illuminance of 1 lx or less.
[Characteristic variation of liquid crystal display]
A polarizing plate sample was prepared by randomly selecting 5 locations out of all 20 locations where the phase difference variation was measured as described above, and the luminance contrast ratio and color shift were measured by bonding the polarizing plate to a liquid crystal display device. Variation was obtained from the measurement results of a total of five points.

[Adhesion between laminated optical film layers]
Adhesion was confirmed by attaching the laminated optical film to a glass plate with a double-sided tape, putting a cutter blade between each layer and peeling it, and evaluated it according to the following criteria.
A: The cutter blade does not enter between the layers and does not peel off.
○: The cutter blade enters between the layers, and the peeled portion can be produced, but does not peel continuously.
X: The cutter blade enters the interlayer and peels continuously from the peeled portion.

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, 35 parts of bicyclo [2.2.1] hept-2-ene represented by the following formula (8), 18 parts of 1-hexene (molecular weight regulator), 750 parts of toluene (solvent for ring-opening polymerization reaction) was charged into a nitrogen-substituted reaction vessel, and the solution was 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 each physical property value of the resin (A1).

[Synthesis Example 2] Synthesis of Cyclic Olefin Resin (A2) Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene 53 parts and 8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 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 (A2) was obtained.

  With respect to the obtained resin A2, the hydrogenation rate was 99.9%, the glass transition temperature (Tg) was 125 ° C., the Mn was 30,000, the Mw was 122,000, the molecular weight distribution (Mw / Mn) was 4.07, The logarithmic viscosity was 0.63 dL / g. Table 1 shows the physical property values of the resin (A2).

[Synthesis Example 3] Synthesis of Cyclic Olefin Resin (A3) 8-Methyl-8-methoxycarbonyltetracyclo represented by the above formula (7) [4.4.0.1 ^2,5 . 200 parts of ^1,7,10 ] -3-dodecene, 50 parts of bicyclo [2.2.1] hept-2-ene represented by the above formula (8), 18 parts of 1-hexene (molecular weight regulator), A cyclic olefin resin (A3), which is a hydrogenated polymer, was obtained in the same manner as in Synthesis Example 1 except that was used.
With respect to the obtained resin A3, 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 each physical property value of the resin (A3).

[Synthesis Example 4] Synthesis of Vinyl Aromatic Resin (B1) 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, condenser and 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 (B1) were measured, Mw was 223,000 (Mw / Mn = 2.35), logarithmic viscosity was 0.54 dL / g, and yield was 85. %Met. The composition ratio was as prepared. The obtained polymer was a styrene-methacrylic acid 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) 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%.
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 135,000 (Mw / Mn = 1.85), logarithmic viscosity was 0.46 dL / g, and yield was 80. %Met. The composition ratio was as prepared. The obtained polymer was a styrene-maleic anhydride copolymer, and the glass transition temperature was 128 ° C. Table 1 shows the physical property values of the resin (B2).

Synthesis Example 6 Synthesis of Vinyl Aromatic Resin (B3) In a glass flask equipped with a stirrer, a condenser and a thermometer, 145.6 g (1.40 mol) of styrene, 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 (B3) 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 (B3).

[Preparation Example 1] Preparation of aqueous 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 0 1 part was added, and this was stirred with a stirring blade made of Teflon (registered trademark) and dispersed. After replacing 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 Cyclic Olefin Resin Film (FA1) The cyclic olefin resin (A1) obtained in Synthesis Example 1 was dissolved in dichloromethane so as to have a concentration of 30%, and pentaerythrityl tetrakis as an antioxidant [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] was added in an amount of 0.3 part by weight based on 100 parts by weight of the resin.
Then, using a twin-screw extruder (Toshiba Machine Co., Ltd .; TEM-48), resin was discharged from the strand die by extruding downstream using a gear pump while degassing the solvent with a three-stage vent. After cooling in the cooling water tank, it was sent to a strand cutter and cut into rice grains to obtain pellets.
The pellets were dried at 100 ° C. for 4 hours in a nitrogen atmosphere, then sent to a single screw extruder (90 mmΦ), and quantitative extrusion was performed with a gear pump while melting at 260 ° C., and 260 ° C. using a coat hanger type die. And then cast into a mirror roll set to 125 ° C. Subsequently, the film peeled off from the mirror surface roll was cooled by pressure bonding to two cooling rolls provided on the downstream side of the mirror surface roll. After the cooling roll, the film was peeled off, a masking film was bonded to one side and wound up with a winder to obtain a cyclic olefin-based resin film roll (FA1) having a thickness of 150 μm. The thickness variation was an average value ± 1 μm.

[Production Example 2] Production of Cyclic Olefin Resin Film (FA2) The cyclic olefin resin (A1) obtained in Synthesis Example 1 is 30% concentrated in dichloromethane (solution viscosity at room temperature is 30,000 mPa · s). And 0.1 parts by weight of pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as an antioxidant is added to 100 parts by weight of the resin, Using a sintered metal fiber filter with a pore diameter of 5 μm manufactured by Nippon Pole, filtration was performed while controlling the flow rate of the solution so that the differential pressure was within 0.4 MPa. A PET film (100 μm thick) obtained by subjecting the obtained solution to an hydrophilic treatment (making it easy to adhere) with an acrylic acid system using an “INVEX Lab Coater” manufactured by Inoue Metal Industry installed in a Class 1000 clean room ( The film thickness after drying was applied to “Lumorir U94” manufactured by Toray Industries, Inc. so as to be 150 μm, and this was subjected to primary drying at 50 ° C. and then secondary drying at 90 ° C. The PET film was peeled off to obtain a cyclic olefin resin film roll (FA2). The residual solvent amount of the obtained film was 0.3%. The thickness variation was an average value ± 2 μm.

[Production Example 3] Production of Cyclic Olefin Resin Film (FA3) Manufacture except that cycloolefin resin (A2) obtained in Synthesis Example 2 was used instead of cyclic olefin resin (A1) and cyclohexane was used as the solvent. In the same manner as in Example 1, the resin was pelletized and extruded to form a resin film roll (FA3) having a thickness of 150 μm. The thickness variation was an average value ± 1 μm.
[Production Example 4] Production of Cyclic Olefin Resin Film (FA4) The cyclic olefin resin (A3) obtained in Synthesis Example 3 was used instead of the cyclic olefin resin (A1), and the resin was prepared in the same manner as in Production Example 1. The resin film roll (FA4) having a thickness of 150 μm was obtained by pelletization and extrusion film formation. The thickness variation was an average value ± 1 μm.

[Production Example 5] Production of vinyl aromatic resin film (FB1) The vinyl aromatic resin (B1) obtained in Synthesis Example 4 was used in place of the cyclic olefin resin (A1), and the same procedure as in Production Example 1 was conducted. The resin was pelletized and extruded to form a resin film roll (FB1) having a thickness of 65 μm. The thickness variation was an average value ± 1 μm.
[Production Example 6] Production of vinyl aromatic resin film (FB2) The vinyl aromatic resin (B1) obtained in Synthesis Example 4 was used in place of the cyclic olefin resin (A1), and the same procedure as in Production Example 2 was performed. The resin solution was applied onto a substrate and formed into a film to obtain a resin film roll (FB2) having a thickness of 65 μm. The residual solvent amount of the obtained film was 0.2%. The thickness variation was an average value ± 2 μm.

[Production Example 7] Production of vinyl aromatic resin film (FB3) The vinyl aromatic resin (B2) obtained in Synthesis Example 5 was used in the same manner as in Production Example 1 in place of the cyclic olefin resin (A1). The resin was pelletized and extruded to form a 65 μm thick resin film roll (FB3). The thickness variation was an average value ± 1 μm.
[Production Example 8] Production of vinyl aromatic resin film (FB4) The vinyl aromatic resin (B3) obtained in Synthesis Example 6 was used in the same manner as in Production Example 1 instead of the cyclic olefin resin (A1). The resin was pelletized and extruded to form a 65 μm thick resin film roll (FB4). The thickness variation was an average value ± 1 μm.

[Production Example 9] Production of Polarizer A roll-shaped polyvinyl alcohol (hereinafter also referred to as “PVA”) film having a film thickness of 120 μm has an iodine concentration of 0.03% by weight and a potassium iodide concentration of 0. After continuously uniaxially stretching (pre-stretching) in the longitudinal direction at a stretching ratio of 3 times in a dye bath of 5% by weight of 30 ° C. aqueous solution, the boric acid concentration is 5% by weight and the potassium iodide concentration is 8 In a 55% C. cross-linking bath of an aqueous solution of wt%, 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 10] Production of optical film (negative C plate) and polarizing plate The film roll (150 μm) of the cyclic olefin resin (A1) obtained in Synthesis Example 1 was stretched at 133 ° C. and stretched at 1.6 times. The film was stretched longitudinally, and then stretched transversely by a tenter at a stretching temperature of 135 ° C. and a stretching ratio of 2.4 times to obtain a stretched film having a thickness of 68 μm. The in-plane retardation R550 of the obtained stretched film was 0 to 2 nm, and Rth = 190 ± 5 nm. (Rth is one of the indices representing the thickness direction retardation, and is represented by {(nx + ny) / 2−nz} × d. Nx is the maximum in-plane refractive index at the optical film measurement point, and ny is the surface. (Wherein nz represents the refractive index in the thickness direction of the stretched film perpendicular to nx and ny, and d represents the film thickness (nm) at the measurement point.)
This film was made to have a roll-shaped film on one side of the polarizer obtained in Production Example 1, and both were continuously pasted using the aqueous adhesive obtained in Preparation Example 1, and the other side of the polarizer was adhered. A saponified 80 μm-thick triacetyl cellulose (hereinafter also referred to as “TAC”) film was attached to the surface using an adhesive composed of a 5% PVA aqueous solution to obtain a polarizing plate (P0). . The obtained polarizing plate had a single transmittance of 42.1% and a polarization degree of 99.9%.

[Example 1]
<Manufacture of laminated optical film (F1)>
A cyclic olefin resin film roll (FA1) and a vinyl aromatic resin film roll (FB1) are each fed out on the same line, and both sides are sandwiched by polyimide films fed from two commercially available heat-resistant polyimide film rolls (polyimide film). / FA1 / FB1 / polyimide film), and the temperature-controlled pinch roll was heated to 160 ° C. and passed so that air (bubbles) was not caught between FA1 and FB1. After passing through the pinch roll and cooling the film, the polyimide films on both outer surfaces were peeled off to obtain an original film roll laminated in a configuration of FA1 (150 μm) / FB1 (65 μm). The thickness variation of each layer was an average value ± 1 μm, and the total thickness variation was an average value ± 2 μm.
This original film roll was transversely stretched by a tenter at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times to obtain a laminated optical film (F1) having a thickness of 71 μm. The in-plane retardation of the obtained laminated optical film was R450 = 83 nm, R550 = 95 nm, R650 = 101 nm, and NZ = 1.50. The phase difference variation was within an average value ± 3 nm. When the adhesiveness of this laminated optical film was confirmed, the adhesiveness was good without peeling.

<Production of Polarizing Plate (P1) and Evaluation of Liquid Crystal Display>
For the obtained laminated optical film (F1), roll-like films are aligned on one side of the polarizer obtained in Production Example 9 (the stretching direction which is the absorption axis of the polarizer and the stretching direction of the laminated optical film are orthogonal) ), The vinyl aromatic resin layer faces the polarizer side, both are continuously bonded using the aqueous adhesive obtained in Preparation Example 1, and the other surface of the polarizer is As a protective film, a saponified TAC film having a thickness of 80 μm was bonded using an adhesive composed of a 5% PVA aqueous solution to obtain a polarizing plate (P1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.1% and 99.9%, respectively.
In order to evaluate the properties of this polarizing plate, the polarizing plate and the position attached to the front and back surfaces of the liquid crystal panel of Samsung Electronics Co., Ltd. liquid crystal television (model number LN40R81BD) which is a VA mode liquid crystal display device The phase difference film is peeled off, and in this peeled place, the transmission axis of the polarizing plate originally bonded to the negative C plate polarizing plate (P0) obtained in Production Example 10 on the back surface and the polarizing plate (P1) on the front surface. It was pasted together using an acrylic transparent adhesive film. At this time, both the back surface and the front surface were bonded so that the retardation film (laminated optical film) of the polarizing plate was on the liquid crystal cell side.
When the contrast ratio of the liquid crystal television having this polarizing plate was measured at five points, the maximum value was 5130 to 5210 and the minimum value was 95 to 105 in the range of all directions and polar angles of 0 to 80 degrees. There was little variation, and no unevenness was visually observed. In a black display state, when the azimuth angle was 45 degrees and five color shifts at polar angles of 0 to 60 degrees were measured, Δu′v ′ = 0.03 to 0.05. In the production of the polarizing plate and the evaluation of the liquid crystal display device, no peeling occurred between the layers of the laminated optical film.

[Example 2]
<Manufacture of laminated optical film (F2)>
It is laminated with the structure of FA2 (150 μm) / FB2 (65 μm) in the same manner as in Example 1 except that (FA2) is used as the cyclic olefin resin film roll and (FB2) is used as the vinyl aromatic resin film roll. A raw film roll was obtained. The thickness variation of each layer was an average value ± 2 μm, and the total thickness variation was an average value ± 3 μm.
This original film roll was transversely stretched by a tenter at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times to obtain a laminated optical film (F2) having a thickness of 70 μm. The in-plane retardation of the obtained laminated optical film was R450 = 84 nm, R550 = 95 nm, R650 = 101 nm, and NZ = 1.52. The phase difference variation was within an average value ± 3 nm. When the adhesiveness of this laminated optical film was confirmed, the adhesiveness was good without peeling.
<Production of Polarizing Plate (P2) and Evaluation of Liquid Crystal Display>
A polarizing plate (P2) was obtained in the same manner as in Example 1 except that the laminated optical film (F2) was used instead of the laminated optical film (F1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.9% and 99.9%, respectively. The contrast ratio of the liquid crystal television was measured in the same manner as in Example 1 except that the polarizing plate (P2) was used in place of the polarizing plate (P1). Maximum values: 5090-5170, minimum values: 95-100, high numerical values, little variation in measured values, and no unevenness was observed visually. In a black display state, when the azimuth angle was 45 degrees and the color shift at a polar angle of 0 to 60 degrees was measured at 5 points, Δu′v ′ = 0.04 to 0.05. In the production of the polarizing plate and the evaluation of the liquid crystal display device, no peeling occurred between the layers of the laminated optical film.
<Production of Polarizing Plate (P2 ′) and Evaluation of Liquid Crystal Display>
When laminating the polarizer and the laminated optical film with a water-based adhesive, the polarizing plate (P2 ′) is the same as the polarizing plate (P2) except that the cyclic olefin-based resin layer faces the polarizer. Obtained. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.9% and 99.9%, respectively. The contrast ratio of the liquid crystal television was measured at five points in the same manner as in Example 1 except that the polarizing plate (P2 ′) was used instead of the polarizing plate (P1). The maximum value: 5080 to 5150 and the minimum value: 95 to 100, which are high numerical values, there are few variations in measured values, and no unevenness was observed visually. In a black display state, when the azimuth angle was 45 degrees and the color shift at a polar angle of 0 to 60 degrees was measured at 5 points, Δu′v ′ = 0.04 to 0.05. In the production of the polarizing plate and the evaluation of the liquid crystal display device, no peeling occurred between the layers of the laminated optical film.

[Example 3]
<Manufacture of laminated optical film (F3)>
Except having used (FB3) as a vinyl aromatic resin film roll, it carried out similarly to Example 1, and obtained the raw film roll laminated | stacked by the structure of FA1 (150 micrometers) / FB3 (65 micrometers). The thickness variation of each layer was an average value ± 1 μm, and the total thickness variation was an average value ± 2 μm.
This original film roll was transversely stretched by a tenter at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times to obtain a laminated optical film (F3) having a thickness of 72 μm. The in-plane retardation of the obtained laminated optical film was R450 = 86 nm, R550 = 94 nm, R650 = 98 nm, and NZ = 1.54. The phase difference variation was within an average value ± 3 nm. When the adhesiveness of this laminated optical film was confirmed, the adhesiveness was good without peeling.
<Production of Polarizing Plate (P3) and Evaluation of Liquid Crystal Display>
A polarizing plate (P3) was obtained in the same manner as in Example 1 except that the laminated optical film (F3) was used instead of the laminated optical film (F1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively. The contrast ratio of the liquid crystal television was measured at five points in the same manner as in Example 1 except that the polarizing plate (P3) was used instead of the polarizing plate (P1). Maximum values: 5120 to 5180 and minimum values: 90 to 95, which are high numerical values, there is little variation in measured values, and no unevenness was observed visually. In a black display state, when the azimuth angle was 45 degrees and the color shift at a polar angle of 0 to 60 degrees was measured at 5 points, Δu′v ′ = 0.04 to 0.05. In the production of the polarizing plate and the evaluation of the liquid crystal display device, no peeling occurred between the layers of the laminated optical film.

[Example 4]
<Manufacture of laminated optical film (F4)>
Except having used (FA3) as a cyclic olefin resin film roll, it carried out similarly to Example 1, and obtained the raw film roll laminated | stacked by the structure of FA3 (150 micrometers) / FB1 (65 micrometers). The thickness variation of each layer was an average value ± 1 μm, and the total thickness variation was an average value ± 2 μm.
This original film roll was transversely stretched by a tenter at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times to obtain a laminated optical film (F4) having a thickness of 72 μm. The in-plane retardation of the obtained laminated optical film was R450 = 87 nm, R550 = 95 nm, R650 = 99 nm, and NZ = 1.52. The phase difference variation was within an average value ± 3 nm. When the adhesiveness of this laminated optical film was confirmed, it was possible to produce a peeled portion, but it broke during the peeling and did not peel continuously.
<Manufacture 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 (F4) was used instead of the laminated optical film (F1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.9% and 99.9%, respectively. The contrast ratio of the liquid crystal television was measured in the same manner as in Example 1 except that the polarizing plate (P4) was used in place of the polarizing plate (P1). Maximum values: 5040 to 5100, minimum values: 80 to 90, high numerical values, little variation in measured values, and no unevenness was observed visually. In the black display state, when the azimuth angle was 45 degrees and the color shift at the polar angle of 0 to 60 degrees was measured at five points, Δu′v ′ = 0.05 to 0.07. In the production of the polarizing plate and the evaluation of the liquid crystal display device, no peeling occurred between the layers of the laminated optical film.

[Comparative Example 1]
<Manufacture of laminated optical film (F5)>
Except having used (FA4) as a cyclic olefin resin film roll, it carried out similarly to Example 1, and obtained the raw film roll laminated | stacked by the structure of FA4 (150 micrometers) / FB1 (65 micrometers). The thickness variation of each layer was an average value ± 1 μm, and the total thickness variation was an average value ± 2 μm.
This original film roll was transversely stretched by a tenter at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times to obtain a laminated optical film (F5) having a thickness of 72 μm. The in-plane retardation of the obtained laminated optical film is R450 = 91 nm, R550 = 85 nm, R650 = 82 nm (Note: no phase difference of ARTON appears, and negative dispersion results in positive dispersion), and NZ = −0 0.03. The phase difference variation was within an average value ± 3 nm. When the adhesiveness of this laminated optical film was confirmed, the adhesiveness was good without peeling.
<Production of Polarizing Plate (P5) and Evaluation of Liquid Crystal Display>
A polarizing plate (P5) was obtained in the same manner as in Example 1 except that the laminated optical film (F5) was used instead of the laminated optical film (F1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.8% and 99.9%, respectively. The contrast ratio of the liquid crystal television was measured at five points in the same manner as in Example 1 except that the polarizing plate (P5) was used instead of the polarizing plate (P1). Maximum value: 4900-5030, minimum value: 7-10 (Note: the axial direction is different and the oblique contrast is bad). In the black display state, when the color shift at the polar angle of 0 to 60 degrees was measured at an azimuth angle of 45 degrees, Δu′v ′ = 0.18 to 0.20. In the production of the polarizing plate and the evaluation of the liquid crystal display device, no peeling occurred between the layers of the laminated optical film.
The cyclic olefin resin (A3) used in the laminated optical film (F5) has a low glass transition temperature, and the film (FA4) formed with the resin (A3) when stretched does not exhibit a predetermined retardation, and is laminated. Since the optical film does not have the desired retardation, the front contrast ratio is not a problem, but the contrast ratio in the oblique direction is poor and the color shift is also large.

[Comparative Example 2] (Extruded Zeonore and Extruded PSt are described as thermal lamination and thickness variation. → No reverse wavelength appears, interlayer adhesion is poor)
<Manufacture of laminated optical film (F6)>
Laminated in the configuration of FA3 (150 μm) / FB4 (65 μm) in the same manner as in Example 1 except that (FA3) was used as the cyclic olefin resin film roll and (FB4) was used as the vinyl aromatic resin film roll. The obtained film roll was obtained. The thickness variation of each layer was an average value ± 1 μm, and the total thickness variation was an average value ± 2 μm.
This original film roll was transversely stretched by a tenter at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times to obtain a laminated optical film (F6) having a thickness of 73 μm. The in-plane retardation of the obtained laminated optical film was R450 = 235 nm, R550 = 232 nm, R650 = 230 nm, and NZ = 1.38. The phase difference variation was within an average value ± 3 nm. When the adhesiveness of this laminated optical film was confirmed, the layers were easily separated.
<Production of Polarizing Plate (P6) and Evaluation of Liquid Crystal Display>
A polarizing plate (P6) was obtained in the same manner as in Example 1 except that the laminated optical film (F6) was used instead of the laminated optical film (F1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.9% and 99.9%, respectively. The contrast ratio of the liquid crystal television was measured at five points in the same manner as in Example 1 except that the polarizing plate (P6) was used instead of the polarizing plate (P1). Maximum value: 4990-5120, minimum value: 4-5. In a black display state, when the azimuth angle was 45 degrees and five color shifts at polar angles of 0 to 60 degrees were measured, Δu′v ′ = 0.15 to 0.16. Also in the manufacture of the polarizing plate and the evaluation of the liquid crystal display device, some peeling occurred between the layers of the laminated optical film.
The glass transition temperature of the vinyl aromatic resin (B3) used for the laminated optical film (F6) is low, and the film (FB4) formed with the resin (B3) when stretched does not exhibit a predetermined retardation, Since the laminated optical film does not have the desired retardation, the front contrast ratio is not a problem, but the contrast ratio in the oblique direction is poor and there are many color shifts.

[Comparative Example 3]
<Manufacture of optical film (F7)>
The cyclic olefin resin film roll (FA1) obtained in Production Example 1 was subjected to tenter transverse stretching at a stretching temperature of 140 ° C. and a draw ratio of 3.0 times to obtain an optical film (F7) having a thickness of 52 μm. The in-plane retardation of this optical film was R450 = 121 nm, R550 = 120 nm, R650 = 119 nm, and NZ = 1.33. The phase difference variation was within an average value ± 3 nm.
<Manufacture of polarizing plate (P7) and evaluation of liquid crystal display device>
A polarizing plate (P7) was obtained in the same manner as in Example 1 except that the optical film (F7) was used instead of the laminated optical film (F1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.8% and 99.9%, respectively. The contrast ratio of the liquid crystal television was measured at five points in the same manner as in Example 1 except that the polarizing plate (P7) was used instead of the polarizing plate (P1). Maximum values: 4970-5160 and minimum values: 70-85, which are high numerical values, and no unevenness was observed visually. In addition, when the color shift at the polar angle of 0 to 60 degrees was measured at the azimuth angle of 45 degrees in the black display state, Δu′v ′ = 0.11 to 0.13. Since the optical film F7 does not have reverse wavelength dispersion, the Δu′v ′ value is increased, and the color shift is not improved.

[Comparative Example 4]
<Manufacture of laminated optical film (F8)>
The pellets of the cyclic olefin resin (A1) and the pellets of the vinyl aromatic resin (B1) 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 an A1 layer (150 μm) / A raw film roll having a configuration of B1 layer (65 μm) was obtained.
This original film roll was transversely stretched by a tenter at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times to obtain a laminated optical film (F8) having a thickness of 72 μm. The in-plane retardation of the obtained laminated optical film was R450 = 82 nm, R550 = 95 nm, R650 = 102 nm, and NZ = 1.48. The phase difference variation was large, with an average value within ± 7 nm. When the adhesiveness of this laminated optical film was confirmed, the adhesiveness was good without peeling.
<Production of Polarizing Plate (P8) and Evaluation of Liquid Crystal Display>
A polarizing plate (P8) was obtained in the same manner as in Example 1 except that the laminated optical film (F8) was used instead of the laminated optical film (F1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively. The contrast ratio of the liquid crystal television was measured in the same manner as in Example 1 except that the polarizing plate (P8) was used instead of the polarizing plate (P1). Maximum value: 5130 to 5250, minimum value: 40 to 110, and variation in the minimum contrast ratio was observed. Further, when 5 color shifts at polar angles of 0 to 60 degrees were measured at an azimuth angle of 45 degrees in the black display state, Δu′v ′ = 0.03 to 0.08 and variation was observed. In the production of the polarizing plate and the evaluation of the liquid crystal display device, no peeling occurred between the layers of the laminated optical film.
Due to the large phase difference variation of the laminated optical film (F8), good contrast ratio and color shift were obtained at the location that matched the target phase difference, but both contrast ratio and color shift were obtained at the location outside the target phase difference. The characteristics deteriorated, and variation was observed depending on the location.

  From the above results, Table 1 shows the evaluation results of the laminated optical film, the evaluation results of the liquid crystal display device, and the panel characteristics before peeling the polarizing plate from the liquid crystal television as a reference.

Claims (9)

A cyclic olefin resin film comprising a copolymer having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2);
A step of laminating a vinyl aromatic resin film made of a styrene- (meth) acrylic acid copolymer by a lamination method to obtain a raw film in which a cyclic olefin resin layer and a vinyl aromatic resin layer are laminated; And a step of uniaxially stretching the obtained raw film in a direction orthogonal to the longitudinal direction of the film, the laminated optics satisfying all the characteristics represented by the following formulas (i) to (iii) A method for producing a film.
R450 <R550 <R650 (i)
1.0 <R650 / R550 <1.2 (ii)
70 nm ≦ R550 ≦ 150 nm (iii)
[In the above formulas (i) to (iii), R450, R550, and R650 represent the in-plane retardation of the laminated optical film at wavelengths of 450 nm, 550 nm, and 650 nm, respectively. ]

[Wherein, m is an integer of 1 or more, p is an integer of 0 or more, and X is independently a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —. R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon having 1 to 30 carbon atoms, which may have a linking group containing oxygen, nitrogen, sulfur or silicon 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 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. ]

[ Wherein Y represents 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 each independently represents 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 oxygen, nitrogen, sulfur or silicon; 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 may be bonded to each other to form a carbocyclic or heterocyclic ring. The carbocycle or heterocycle may be a monocyclic structure or a polycyclic structure. ]   The method for producing a laminated optical film according to claim 1, wherein the cyclic olefin resin film and the vinyl aromatic resin film are each formed by either a melt extrusion method or a solution casting method. Method for producing a laminated optical film according to any one of claims 1-2 which is a cyclic olefin-based resin layer and a vinyl aromatic resin layer, characterized in that direct contact. And a cycloolefin resin and a vinyl aromatic resin, a manufacturing method of the laminated optical film according to any one of claims 1 to 3, characterized in that a relationship satisfying the following formula (iv).
| TgA (° C.) − TgB (° C.) | ≦ 20 (° C.) (iv)
[Wherein, TgA represents the glass transition temperature of the cyclic olefin resin, and TgB represents the glass transition temperature of the vinyl aromatic resin. ] Characterized in that it is obtained by the method according to any one of claims 1-4, a laminated optical film. The laminated optical film according to claim 5 , wherein the following formula (v) is satisfied.
1.0 ≦ NZ ≦ 3.0 (v)
[In the above formula (v), NZ is a coefficient represented by NZ = (nx−nz) / (nx−ny)]. Here, nx represents the maximum refractive index in the laminated optical film plane, ny represents the refractive index in the laminated optical film plane in the direction orthogonal to the maximum refractive index direction, and nz represents the refractive index in the laminated optical film thickness direction. These are all values at a wavelength of 550 nm. ] The laminated optical film according to claim 5 or 6 , wherein the glass transition temperature of the cyclic olefin resin and the glass transition temperature of the vinyl aromatic resin are both 110 ° C or higher. A polarizing plate on at least one surface of a polarizer, characterized in that formed by laminating with an adhesive or pressure-sensitive adhesive of the laminated optical film according to any one of claims 5-7. A liquid crystal display device comprising the polarizing plate according to claim 8 .