JP5186926B2 - Method for producing laminated optical film, laminated optical film and use thereof - Google Patents

Description

  The present invention relates to a method for producing a laminated optical film, a laminated optical film, and uses thereof. Specifically, the present invention relates to a method for producing a laminated optical film having a cyclic olefin-based resin layer and a vinyl aromatic resin layer, a laminated optical film obtained by the production method, and a polarization using the laminated optical film. The present invention relates to a plate 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 of 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.

Patent Document 3 proposes a method of realizing reverse wavelength dispersion by laminating a layer having a positive intrinsic birefringence and a layer having a negative intrinsic birefringence by coating and stretching. However, there is no mention of the phase difference value at the oblique viewing angle, the reverse wavelength dispersion, and the panel characteristics, which are particularly important for the viewing angle compensation, and the interlayer adhesion, which is a mounting problem, is also mentioned. Absent. In addition, stretching with the residual solvent amount kept constant to develop a predetermined phase difference is difficult and phase difference unevenness is likely to occur. 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 JP2007-199616

  The present invention provides a laminated optical film having a high contrast ratio when the screen is viewed from an oblique direction in a liquid crystal display device, a small color shift amount when the screen is viewed from an oblique direction, and a more uniform screen display. And a manufacturing method thereof, and a polarizing plate and a liquid crystal display device using the same.

  As a result of intensive investigations in view of the background as described above, the present inventors have ensured a predetermined phase difference when viewed from an oblique direction, in which a laminated optical film manufactured by a specific method cannot be achieved by the prior art. The inventors have found that the reverse wavelength dispersion can be ensured and that the adhesion of each layer of the laminated film can be ensured, and the present invention has been completed.

That is, the method for producing a laminated optical film of the present invention includes:
On at least one surface of the base film made of either the cyclic olefin resin (A) or the vinyl aromatic resin (B), the base material out of the cyclic olefin resin (A) and the vinyl aromatic resin (B). Laminating a resin that does not constitute a film by a coating method,
Producing a raw film having a cyclic olefin resin (A) layer and a vinyl aromatic resin (B) layer;
A step of uniaxially stretching the obtained raw film in a direction perpendicular to the film longitudinal direction,
The in-plane retardation (R450) at a wavelength of 450 nm, the in-plane retardation at a wavelength of 550 nm (R550), and the in-plane retardation at a wavelength of 650 nm (R650) all satisfy the following formulas (i), (ii), and (iii) It is characterized by obtaining a laminated optical film that satisfies the requirements.

R450 ≦ R550 ≦ R650 (i)
1.0 ≦ R650 / R550 ≦ 1.2 (ii)
70 nm ≦ R550 ≦ 150 nm (iii)
In such a method for producing an optical film of the present invention, the cyclic olefin-based resin (A) has a structural unit represented by the following formula (1) and a copolymer represented by the following formula (2). Tona Ru.

[In the formula (1), 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 formula: —CH ₂ CH ₂ —. R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon Or a polar group, 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 are bonded to each other to form a carbocyclic ring or A heterocycle may be formed, and the carbocycle or heterocycle may be a monocyclic structure or a polycyclic structure. ]

[In Formula (2), Y is a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —, and R ^{5 to} R ⁸ are each independently a hydrogen atom; A halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon; or a polar group, R ⁵ and R ⁶ and / or Alternatively, R ⁷ and R ⁸ may be combined to form a divalent hydrocarbon group, and R ⁵ or R ⁶ and R ⁷ or R ⁸ are bonded to each other to form a carbocyclic or heterocyclic ring. The carbocycle or heterocycle may be a monocyclic structure or a polycyclic structure. ]
In the method for producing a laminated optical film of the present invention, the vinyl aromatic resin (B) is a styrene- (meth) acrylic acid copolymer , or the vinyl aromatic resin (B) is styrene-anhydrous. Ru maleic acid copolymer der.

  In the method for producing a laminated optical film of the present invention, the glass transition temperature (Tg (A)) of the cyclic olefin resin (A) and the glass transition temperature (Tg (B)) of the vinyl aromatic resin (B). The difference is preferably within 20 ° C.

In the method for producing a laminated optical film of the present invention, the step of producing a raw film includes a vinyl aromatic resin (B) on at least one surface of a base film made of a cyclic olefin resin (A).
) Is preferably a step of forming a laminated film by a coating method.

The laminated optical film of the present invention is obtained by the method for producing a laminated optical film of the present invention.
In the laminated optical film of the present invention, the cyclic olefin resin (A) layer and the vinyl aromatic resin (B) layer are preferably laminated directly.

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

  According to the present invention, it is possible to provide a method for producing a laminated optical film and a laminated optical film that ensure a predetermined phase difference and reverse wavelength dispersion when viewed from an oblique direction, and that are excellent in adhesion of each layer of the laminated film. it can. Further, according to the present invention, by using the laminated optical film of the present invention or the polarizing plate having the same, the contrast ratio when the screen is viewed from an oblique direction in a liquid crystal display device is high, and the screen is viewed from an oblique direction. It is possible to provide a liquid crystal display device that has a small color shift amount when viewed and enables a more uniform screen display.

Hereinafter, the present invention will be specifically described.
[Method for producing laminated optical film]
The method for producing a laminated optical film of the present invention comprises a cyclic olefin resin (A) and a vinyl fragrance on at least one surface of a base film made of either a cyclic olefin resin (A) or a vinyl aromatic resin (B). A raw film having a cyclic olefin resin (A) layer and a vinyl aromatic resin (B) layer obtained by laminating and forming a resin that does not constitute a base film of the group resin (B) by a coating method And a step of uniaxially stretching the obtained raw film in a direction perpendicular to the film longitudinal direction.

(A) Cyclic Olefin Resin As the cyclic olefin resin used in the present invention, a resin obtained by polymerizing or copolymerizing a cyclic olefin monomer that is a compound having a norbornene skeleton, and hydrogenating it as necessary. Any of these can be used. Here, the polymerization or copolymerization of the cyclic olefin monomer may be addition polymerization or ring-opening polymerization.

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

[In the formula (1), m 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 formula: —CH ₂ CH ₂ —. R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon Or a polar group, 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 are bonded to each other to form a carbocyclic ring or A heterocycle may be formed, and the carbocycle or heterocycle may be a monocyclic structure or a polycyclic structure. ]

[In Formula (2), Y is a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —, and R ^{5 to} R ⁸ are each independently a hydrogen atom; A halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon; or a polar group, R ⁵ and R ⁶ and / or Alternatively, R ⁷ and R ⁸ may be combined to form a divalent hydrocarbon group, and R ⁵ or R ⁶ and R ⁷ or R ⁸ are 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 copolymer having the structural unit represented by the above formula (1) and the structural unit represented by the above formula (2) is composed of one or more monomers represented by the following formula (1m) (hereinafter referred to as “ Monomer (1) ”), one or more monomers represented by the following formula (2m) (hereinafter also referred to as“ monomer (2) ”), and other It is obtained by copolymerizing with a copolymerizable monomer.

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

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

Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.
Examples of the hydrocarbon group having 1 to 30 carbon atoms include alkyl groups such as methyl group, ethyl group and propyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group, allyl group and propenyl group. 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, — (CH ₂ ) m — (wherein m is 1 to 1).
An alkylene group represented by an integer of 0); a linking group containing oxygen, nitrogen, sulfur or silicon (for example, a carbonyl group (—CO—), an oxycarbonyl group (—O (CO) —), a sulfone group (— SO ₂ -), ether bond (-O-), thioether bond (-S-), an imino group (
-NH-), amide bond (-NHCO -, - CONH-), siloxane bond (-OSi (R ₂₎ - (wherein, R is methyl, an alkyl group of ethyl, etc.)) and the like, these multiple A linking group containing

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 thereof include phenoxycarbonyl group, naphthyloxycarbonyl group, fluorenyloxycarbonyl group, biphenylyloxycarbonyl group and the like; examples of triorganosiloxy group include trimethylsiloxy group and triethylsiloxy group; Examples thereof include trimethylsilyl group and triethylsilyl group; examples of amino group include primary amino group; examples of alkoxysilyl group include trimethoxysilyl group and triethoxysilyl group; Acetyl group, a propionyl group, (meth) acryloyl group, benzoyl group, naphthoyl group and the like.

More specific examples of the preferable cyclic olefin-based resin used in the present invention include copolymers shown in the following <1> to <3>. Of these, the copolymer shown in <3> is particularly preferred because of excellent thermal stability and excellent optical properties.
<1> A ring-opening copolymer of the monomer (1) and the monomer (2).
<2> A ring-opening copolymer of the monomer (1), the monomer (2) and other copolymerizable monomers. <3> A hydrogenated product of the ring-opening copolymer of <1> and <2>.

<Monomer (1)>
The structural unit (1) is derived from the monomer (1). Specific examples of the monomer (1) are given below, but the present invention is not limited to these specific examples. Moreover, you may use 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-Eicosen,
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 . 1 ^7,10 ] -3-dodecene.

Among these, it is preferable to use the monomer (1) having at least one polar group in the molecule. That is, in the above formula (1m), R ¹ and R ³ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ² and R ⁴ are a hydrogen atom or a monovalent organic group, ²
And those in which at least one of R ⁴ is a polar group other than a hydrogen atom or a hydrocarbon group are preferred because they enhance adhesion and adhesion to other materials.

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

Further, at least one of R ² and R ⁴ is represented by formula (3):
^{_{- (CH 2) n COOR 9}} ... (3)
[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 (3) 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 can be used.

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

  Furthermore, in the above formula (1m), the fact that an alkyl group is further bonded to the carbon atom bonded to the polar group represented by the formula (3) 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 (1m) is preferable in that a copolymer having a high glass transition temperature is obtained.
Specific examples of the monomer (1) include 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene increases the glass transition temperature of the obtained copolymer, hardly receives any adverse effects such as deformation due to water absorption, and has good water adhesion to other materials. 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,
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 (2m) are all hydrogen atoms, or any one is a hydrocarbon group having 1 to 30 carbon atoms and the other is a hydrogen atom, 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, improve resin toughness, and glass transition. This is preferable in that temperature adjustment and phase difference development can be improved.

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

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

<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. 0 ^2,6 ] -3-decene, dicyclopentadiene, 5-methyl-5-
Mention may be made of cycloolefins such as methoxycarbonylbicyclo [2.2.1] -2-heptene. The number of carbon atoms in the cycloolefin is preferably 4-20, and more preferably 5-12. These copolymerizable monomers are useful for modifying the resin, such as improving retardation development, adjusting Tg, and improving coating properties.

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

<Ring-opening polymerization catalyst>
The ring-opening polymerization reaction of the specific monomer is 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) include n-C ₄ H ₉ Li, (C ₂ H ₅ ) ₃ A
l, (C ₂ H ₅ ) ₂ AlCl, (C ₂ H ₅ ) _1.5 AlCl _1.5 , (C ₂ H ₅ ) AlCl ₂ , methylaluminoxane, LiH and the like, the compounds described in JP-A-1-240517 Can do.

  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.
Moreover, the number average molecular weight (Mn) of polystyrene conversion measured by gel permeation chromatography (GPC) is 8,000-10 as the average molecular weight of cyclic olefin resin.
Those having a weight average molecular weight (Mw) of 20,000 to 300,000 are preferred.

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

(B) Vinyl aromatic resin The vinyl aromatic resin (B) used in the present invention has a structural unit represented by the following formula (4) (hereinafter also referred to as structural unit (4)).

[In the formula (4), 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 structural unit (4) include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, p-trifluoromethylstyrene, p-methoxystyrene, and p-hydroxystyrene. , P-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, p-tertbutoxystyrene, 2,4,6-trimethylstyrene, p-isopropenylphenol and the like. . Any of these monomers may be used alone, or two or more of these monomers may be used in combination. Of these monomers, styrene, α-methylstyrene, p-hydroxystyrene, and p-isopropenylphenol are preferably used alone or in combination.

  Furthermore, the vinyl aromatic resin (B) used in the present invention has a structural unit represented by the following formula (5) together with the structural unit (4) (hereinafter also referred to as the structural unit (5)) and / or the following formula ( It is preferable to have a structural unit represented by 6) (hereinafter also referred to as structural unit (6)).

[In Formula (5), X is an oxygen atom or a nitrogen atom which has a substituent. In the formula (6), R ¹⁴ is a hydrogen atom or a methyl group, and R ¹⁵ is 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 used in the present invention may have a structure containing both the structural unit (5) and the structural unit (6) together with the structural unit (4). The structural unit (5) and the structural unit (6) A structure including only one of them may be used. Further, the acid anhydride structure or imide structure of the repeating unit (5) may be hydrolyzed to a dicarboxylic acid structure or an amic acid structure.

Specific examples of the monomer for deriving the structural unit (5) include N-substituted maleimides such as maleic anhydride, maleimide and N-phenylmaleimide, maleic acid and derivatives thereof, fumaric acid and derivatives thereof, and the like. Any of these monomers may be used alone.
More than one type may be used in combination. Of these monomers, maleic anhydride and N-phenylmaleimide are preferably used in terms of heat resistance and adhesion to the A layer.

  Specific examples of the monomer for deriving the structural unit (6) 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 two or more of these monomers may be used in combination. Of these monomers, (meth) acrylic acid and methyl (meth) acrylate are preferably used in terms of heat resistance and adhesion to the A layer.

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

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

The vinyl aromatic resin (B) used in the present invention has a logarithmic viscosity (η) measured in a chlorobenzene solution (concentration 0.5 g / dL) at 30 ° C. of 0.1 to 3.0 dL / g. It is 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. If the molecular weight is too large, the solution viscosity becomes too high, and the productivity and workability of the resin composition used in the present invention may deteriorate.

The molecular weight distribution (Mw / Mn) of the vinyl aromatic resin (B) is usually 1.0 to 10, preferably 1.2 to 5.0, more preferably 1.2 to 4.0.
In the vinyl aromatic resin (B) used in the present invention, the structural unit (4) and, if necessary, the structural units (5) and / or the structural units (6) are appropriately selected from the above monomers. It is preferably produced by a polymerization reaction in the presence of a polymerization initiator. As the polymerization initiator, it is preferable to use a radical polymerization initiator, an anionic polymerization catalyst, a coordination polymerization catalyst, a cationic polymerization catalyst or the like, and it is particularly preferable to use a radical polymerization initiator.

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

Organic peroxides include diacetyl peroxide, dibenzoyl peroxide, diisobutyroyl peroxide, di (2,4-dichlorobenzoyl) peroxide, di (3,5,5-trimethylhexanoyl) peroxide, di Diacyl peroxides such as octanoyl peroxide, dilauroyl peroxide, distearoyl peroxide, bis {4- (m-toluoyl) benzoyl} peroxide;
Ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, acetylacetone peroxide;
Hydrogen peroxide, t-butyl hydroperoxide, α-cumene hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, t-hexyl hydro Hydroperoxides such as peroxides;
Di-t-butyl peroxide, dicumyl peroxide, dilauryl peroxide, α, α′-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-
Dialkyl peroxides such as 2,5-bis (t-butylperoxy) 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, 2,2′-azobis [2-methyl-N
-{1,1-bis (hydroxymethyl) -2-hydroxyethyl} propionamide], 2,2'-azobis [2-methyl-N- {2- (1-hydroxybutyl)} propionamide], 2, 2'-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-azobis [2- (
5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2 ′
Azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2′- Azobis [2- (3,4,5,6-tetrahydropyrimidine-
2-yl) propane] dihydrochloride, 2,2′-azobis [2- {1- (2-hydroxyethyl) -2-imidazolin-2-yl} propane] dihydrochloride, 2,2′-azobis [ 2- (2-imidazolin-2-yl) propane], 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (
2-carboxyethyl) -2-methyl-propionamidine], 2,2′-azobis (2
-Methylpropionamidoxime), dimethyl 2,2'-azobisbutyrate, 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis (2,4,4-trimethylpentane), etc. However, 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 0.03 mol%, based on 100 mol% of the total amount of monomers for inducing the vinyl aromatic resin (B). It is 05-2 mol%.

  Furthermore, a catalyst may be used for 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 above 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) with respect to 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 (Tg (B)) of the vinyl aromatic resin (B) used in the present invention is preferably 110 to 200 ° C., more preferably 120 to 170 ° C., in order to ensure thermal stability and stretch processability. is there. In this invention, it is preferable that the difference of Tg (B) and the glass transition temperature (Tg (A)) of cyclic olefin resin (A) is small. Specifically, the difference (| Tg (A) between the glass transition temperature (Tg (A)) of the cyclic olefin resin (A) and the glass transition temperature (Tg (B)) of the vinyl aromatic resin (B). ) -Tg (B) |) is preferably within 30 ° C., preferably within 20 ° C., more preferably within 15 ° C., still more preferably within 12 ° C., and particularly preferably within 10 ° C.

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

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

Production of Raw Film In the production method of the laminated optical film of the present invention, the other resin, that is, at least one side of the base film made of either the cyclic olefin resin (A) or the vinyl aromatic compound (B), that is, Of the cyclic olefin resin (A) and the vinyl aromatic resin (B), a resin that does not constitute a base film is laminated and formed by a coating method to form a cyclic olefin resin (A) layer (hereinafter referred to as A layer). And a vinyl aromatic resin (B) layer (hereinafter also referred to as B layer).

  The base film is not particularly limited and can be produced by a known method. That is, the base film made of the cyclic olefin resin (A) is a known method such as melt extrusion molding or solution cast molding of the cyclic olefin resin (A) or the resin composition containing the cyclic olefin resin (A). To form a film. Further, the base film made of the vinyl aromatic resin (B) is prepared by subjecting the resin composition containing the vinyl aromatic resin (B) or the vinyl aromatic resin (B) to melt extrusion molding, solution cast molding, or the like. The film can be produced by a known method.

  In the production of the raw film, a resin that does not constitute the base film of the cyclic olefin resin (A) and the vinyl aromatic resin (B) is laminated and formed on at least one surface of the base film by a coating method. . As a coating method, a method of coating a resin for laminating a film on a base film as a resin solution and coating can be employed without limitation. Examples of coating methods include spin coating, lip coating, comma coating, roll coating, die coating, blade coating, dip coating, bar coating, casting film formation, gravure coating, and printing. Law.

  The raw film and the laminated optical film according to the present invention may have at least the A layer and the B layer, but the laminated film composed of two layers of A layer / B layer, A layer / B layer / A layer A laminated film composed of three layers and a laminated film composed of three layers of B layer / A layer / B layer are preferably used from the viewpoints of production efficiency, ensuring strength, optical properties, and phase difference control. A laminated optical film composed of two layers of A layer / B layer is more preferable in terms of optical properties (transparency), retardation control and good productivity that only requires one coating, and a laminated optical film composed of three layers has a cross section. Since it becomes symmetrical, the warp of the film can be prevented, and it is more preferable for obtaining the mechanical strength.

In the present invention, the vinyl aromatic resin solution may be coated on the surface of the A layer as a base material, or the cyclic olefin resin solution may be coated on the surface of the B layer as a base material. Moreover, a resin solution may be coated on both surfaces of a base material, and you may coat further on the resin layer formed by coating. In the present invention, since the coating layer is provided on the optical substrate, a support is not necessary, and the step of peeling from the support or the coating layer peeled from the support on another optical substrate. Since the process of pasting is unnecessary, it is excellent in manufacturing efficiency.

  The solvent used for coating is to dissolve the resin to be coated and further swell the base film appropriately, which provides good coating properties and adhesion between the base film and the coating layer. Desirable to obtain. A solvent that easily dissolves the base film may cause poor appearance and optical characteristics, and a solvent that does not swell the base at all may cause coating failure such as repellency or poor adhesion.

  When the cyclic olefin resin (A) is applied on the base film made of the vinyl aromatic resin (B), the solvents used are aromatic hydrocarbon solvents such as benzene, toluene, xylene, methyl Cellosolves such as cellosolve, ethyl cellosolve, 1-methoxy-2-propanol, ketone solvents such as diacetone alcohol, acetone, cyclohexanone, cyclopentanone, methyl ethyl ketone, methyl isobutyl ketone, ethylcyclohexane, 1,2-dimethylcyclohexane, etc. Alicyclic hydrocarbon solvents, ester solvents such as methyl lactate and ethyl lactate, halogen-containing solvents such as 2,2,3,3-tetrafluoro-1-propanol, methylene chloride, chloroform, chlorobenzene and orthodichlorobenzene , Tetrahydrofuran, diol Ether solvents emissions such as 1-pentanol, alcohol solvents such as 1-butanol, and the like.

In addition to the above, the SP value (solubility parameter) is usually 10 to 30 (MPa ^1/2
), Preferably 10 to 25 (MPa ^1/2 ), more preferably 15 to 25 (MPa ^1/2 ), and particularly preferably 15 to 20 (MPa ^1/2 ). A film having good properties and optical properties can be obtained. These solvents may be used alone or in combination of two or more.

When the vinyl aromatic resin (B) is coated on the base film made of the cyclic olefin resin (A), the solvents used are chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, Halogen-containing solvents such as tetrachloroethylene, chlorobenzene and orthodichlorobenzene, phenols such as phenol and parachlorophenol, aromatic hydrocarbon solvents such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene and chlorobenzene, acetone Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone and N-methyl-2-pyrrolidone, ester solvents such as ethyl acetate and butyl acetate, t-butyl alcohol Alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, alcohol solvents such as 2-methyl-2,4-pentanediol, dimethylformamide, dimethylacetamide Amide solvents such as acetonitrile, nitrile solvents such as acetonitrile, butyronitrile, ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran, dioxane, cellosolv solvents such as carbon disulfide, ethyl cellosolve, butyl cellosolve, etc. . These solvents may be used alone or in combination of two or more.

  In the present invention, the vinyl aromatic resin (B) is more soluble in a variety of solvents than the cyclic olefin resin (A). In addition, it is preferable to select a solvent type that dissolves the resin to be applied and further swells the base material appropriately in order to obtain good coating properties and adhesion between the base material and the coating layer. For this reason, in this invention, it is more preferable to apply the solution of vinyl aromatic resin (B) to the base film which consists of cyclic olefin resin (A), such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, etc. By selecting the ketone solvent, it is more preferable because the resin to be applied can be dissolved and the base material can be appropriately swollen.

The density | concentration of a coating solution is not specifically limited, In the range which does not impair the effect of this invention, it can adjust to arbitrary appropriate density | concentrations. For example, since the viscosity becomes easy to coat, the coating resin such as vinyl aromatic resin (B) is preferably 1 to 100 parts by weight, more preferably 10 to 90 parts per 100 parts by weight of the solvent. Part by weight, more preferably 20 to 80 parts by weight. By setting the ratio of the resin within this range, the viscosity can be easily applied, and at the same time, a desired coating thickness can be obtained.

  The amount of residual solvent in the laminated optical film is preferably 10% by weight or less, more preferably 5% by weight or less, still more preferably 3% by weight or less, and particularly preferably 2% by weight or less. By reducing the amount of residual solvent, it becomes possible to express a desired phase difference by stretching, and long-term storage stability can be obtained. When the residual solvent amount exceeds 10% by weight, the laminated optical film is wrinkled when stretched, the appearance is deteriorated, and a desired phase difference may not be exhibited by stretching due to a decrease in the glass transition temperature.

  It does not specifically limit as a method of adjusting the residual solvent amount in the laminated | multilayer film (raw fabric film) obtained by carrying out lamination | stacking film formation, Arbitrary appropriate methods are employable. For example, a method of blowing hot air to the laminated film, a method of passing the laminated body through a drying chamber at a predetermined temperature for a predetermined time, and the like can be mentioned. The specific conditions for adjusting the amount of residual solvent in the laminated film are appropriately set depending on the thickness of the laminated film, the type of solvent, etc., but the drying temperature is usually desirably lower than the glass transition temperature of each layer of the laminated film. In order to prevent deterioration of the appearance such as foaming and wrinkles, it is desirable to gradually raise the temperature and dry. Usually, it is preferable that the laminated optical film to be transported is dried with hot air in a drying zone provided after coating in the coating line, and drying is repeated as necessary to obtain a desired residual solvent amount.

  Since the cyclic olefin resin (A) and the vinyl aromatic resin (B) used in the present invention are excellent in mutual adhesion, an adhesive layer and an adhesive layer are provided between the film layers, corona treatment, plasma treatment, There is no need to perform easy adhesion treatment such as primer treatment. Sufficient adhesion strength can be obtained in the state where the A layer and the B layer are in direct contact by the interaction of polar groups contained in the repeating units of each resin and adhesion at the interface due to swelling of the base material during coating. Moreover, even if it is after drying and the amount of residual solvent falls, or after extending | stretching, the adhesiveness of A layer and B layer is hold | maintained favorably.

  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 the retardation variation of the laminated optical film to be obtained, and the display uniformity when incorporated in the liquid crystal display device is impaired. Therefore, vertical streaks and wind ripples (mainly length streaks due to poor coating and uneven drying) and cross marks (roll eccentricity, motor pulsation, etc.) that cause thickness variation. It is desirable that the periodic thickness variation) is small. Further, it is desirable that there are few gels, foreign matters, etc. that cause display defects such as bright spots and light leaks as point-like defects. These can be suppressed, for example, by filtering the coating solution, optimizing the drying conditions, reducing the pulsation of the gear pump, polishing the surface of the coating die lip, or the like. The thickness distribution of each layer in the raw film is preferably within ± 10%, more preferably within ± 5%, and particularly preferably within ± 2%.

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 it is preferable to uniaxially stretch in the direction perpendicular to the film longitudinal direction, that is, 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 step in the production method of the present invention, the stretching temperature is a cyclic olefin resin (A).
In order to adjust the phase difference, it is preferable to determine it based on the glass transition temperature (Tg (A)) and the glass transition temperature (Tg (B)) of the vinyl aromatic resin (B). Specifically, (the lower value of Tg (A) and Tg (B)) − 10 (° C.) to (the higher value of Tg (A) and Tg (B)) + 30 (° C.) Range, preferably (the lower value of Tg (A) and Tg (B))-5 (° C.) to (the higher value of Tg (A) and Tg (B)) + 20 (° C.) It is.

Here, as described above, the difference between Tg (A) and Tg (B) (| Tg (A) −Tg (
It is desirable that B) |) be within 30 ° C, preferably within 20 ° C, more preferably within 15 ° C, still more preferably within 12 ° C, and particularly preferably within 10 ° C.

  By setting the stretching temperature, Tg (A) and Tg (B) within the above ranges, the retardation of each of the A layer and the B layer can be controlled simultaneously by stretching, and the desired retardation of the laminated optical film can be easily achieved. Can get to. 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 for stretching the raw film is usually 1.1 to 10 times, preferably 1.2 to 7 times, and more preferably 1.3 to 5 times. In particular, in the transverse uniaxial stretching in which the film is uniaxially stretched in the direction perpendicular to the longitudinal direction of the film, stretching of 1.3 to 5 times is preferable. By stretching the film uniaxially, the optical axis (in-plane maximum refractive index direction) of the laminated optical film of the present invention is perpendicular to the film longitudinal direction. Therefore, the laminated optical film and the polarizer are bonded by roll-to-roll. Productivity is improved. By setting the draw ratio within the above range, the optical axis of the retardation film, the retardation value, the NZ coefficient (described later), or their distribution in the film plane can be suitably controlled, and the contrast ratio is high. Thus, a liquid crystal display device can be realized in which the color shift when the screen is viewed from an oblique direction is small and a uniform screen display is possible.

[Laminated optical film]
The laminated optical film of the present invention is suitably obtained by the production method described above.
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. As a method of laminating the A layer and the B layer, in addition to the above-described coating molding method of coating the resin solution on the base resin film, a known method such as film lamination molding method such as dry lamination, co-extrusion method, etc. Although the method can be used as appropriate, the coating method does not require heating to such a high temperature that the resin is in a fluid state, so there is no deterioration of the resin due to heat, and even a resin that is not suitable for melt extrusion molding is laminated. Since it can form into a film, it is preferable.

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

  Further, it is 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 ± 10%, preferably within an average value ± 5%, and more preferably within an average value ± 2%.

The laminated optical film of the present invention may be an unstretched film or a stretched film, but is preferably a stretched film in order to satisfy the following properties (i) to (iii). .

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 Characteristics of Laminated Optical Film The laminated optical film of the present invention was measured as a laminated optical film. In-plane retardation (R450) at wavelength 450 nm, in-plane retardation (R550) at wavelength 550 nm, and in-plane position at wavelength 650 nm. The measured value of the phase difference (R650) satisfies all the following formulas (i), (ii), and (iii).

R450 ≦ R550 ≦ R650 (i)
1.0 ≦ R650 / R550 ≦ 1.2 (ii)
70 nm ≦ R550 ≦ 150 nm (iii)
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, and an in-plane retardation that effectively functions as an A plate at this time is (iii
), 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 ± 0.04, more preferably within ± 0.03, and particularly preferably within ± 0.02. The range of variation of R550 in (iii) above is preferably ± 7n
Within m, more preferably within ± 5 nm, 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 ± 2 °, more preferably ± It is within 1 °, more preferably within ± 0.7 °, 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), which is a value at a wavelength of 550 nm. Here, nx is the maximum refractive index in the laminated optical film plane, ny is the refractive index in the direction orthogonal to nx in the laminated optical film plane, and nz is the refractive index in the thickness direction of the laminated optical film orthogonal to nx and ny. Represents a rate. However, when the average refractive index of the laminated optical film is Nave, it is expressed as Nave = (nx + ny + nz) / 3, and Nave is a weighted average of the average refractive indexes of the A layer and the B layer in the laminated optical film by the thickness ratio. It is the value. ]
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). 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) Nx, ny, and nz are numerically calculated 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.

Optical characteristics of each layer (in-plane retardation)
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 film having only the A layer The characteristics of each layer can be confirmed by stretching a film having only the B layer under the same conditions as those of the laminated optical film, separately measuring the phase difference, and estimating the approximate phase difference of each layer. 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 (vi) to (x). It is adjusted as follows.

R450A / R550A ≦ 1.04 (vi)
200 nm ≦ R550A ≦ 400 nm (vii)
1.04 <R450B / R550B (viii)
100 nm ≦ R550B ≦ 300 nm (ix)
R550A> R550B (x)
The A layer and the B layer satisfy the above formulas (vi) to (x), so that the laminated optical film satisfies the above formulas (i) to (iii), 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 (x), 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 is 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-described stretching temperature and stretch ratio, each layer can satisfy the above (vi) to (x) 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 (vi) and (viii) 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 (vi) and (viii) is preferably within ± 0.03, more preferably within ± 0.02, and particularly preferably within ± 0.01. (Vii)
The range of variation of R550A and R550B represented by (ix) is preferably within ± 7 nm, more preferably within ± 5 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 ± 2 degrees, more preferably within ± 1 degree, further preferably within ± 0.7 degrees, and particularly preferably within ± 0.5 degrees, based on the film width direction. is there. The optical axis of layer B is preferably within ± 2 degrees, more preferably within ± 1 degree, even more preferably within ± 0.7 degrees, and particularly preferably within ± 0.5 degrees, based on the longitudinal direction of the film. is there.

  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 ± 10%, preferably within an average value ± 5%, 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 A layer to the entire laminated optical film.)
Similarly, 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.

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 (xi) to (xii) are satisfied.

1.0 ≦ NZA ≦ 1.7 (xi)
−1.0 ≦ NZB ≦ 0 (xii)
[In the above formula (xi), 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 (xii), NZB is NZB = (nxB-nzB) / (nx
B-nyB), which 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 (xi) corresponds to a phase difference developed when the cyclic olefin resin layer is stretched in the transverse direction, nxA is the stretching direction, that is, the film width direction, and nyA is orthogonal to the stretching direction, that is, the film longitudinal direction. In the refractive index ellipsoid, it is generally called a positive A plate. The above formula (xii) corresponds to the phase difference that appears when the vinyl aromatic resin layer is stretched horizontally, and nx
B 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 above retardation 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.

  In general, the thickness of the polarizer constituting the polarizing plate is preferably 5 to 80 μm, but is not limited to this in the present invention. 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 a dyeing process, a stretching process, a crosslinking process, or the like in an appropriate order or method, or may be a wire grid type polarizer.

  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) 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.

[Liquid Crystal Display]
The liquid crystal display device of the present invention has the polarizing plate of the present invention, and preferably has the polarizing plate of the present invention. The liquid crystal display device of the present invention is a laminated optical film or polarizing plate having 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 small optical unevenness. Therefore, uniform display is possible.

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present 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. 5.1-5.8 ppm of vinylene groups, 3
. The hydrogenation rate was calculated after calculating the monomer composition from the integrated value of 7 ppm methoxy group and 0.6 to 2.8 ppm 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, sample concentration 0.5 g / dL in chlorobenzene, temperature 30
The logarithmic viscosity was measured at a temperature of ° C.

[Thickness]
The cross section of the laminated optical film was measured 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.

[Residual solvent amount]
The obtained laminated optical film 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. Was calculated.

Residual solvent amount (% by weight) = [(XY) / X] × 100
[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.

[Degree of polarization]
The polarization degree and single transmittance of the polarizing plate were measured using V-7300 manufactured by JASCO Corporation.
[Measurement of contrast ratio of liquid crystal display]
The brightness, viewing angle, contrast ratio, and color shift of the liquid crystal panel were measured in a dark room with an illuminance of 1 lx or less using “EZ contrast-XL88” manufactured by ELDIM.

[Adhesion]
Adhesion was confirmed by attaching the laminated optical film to a glass plate with a double-sided tape and putting a cutter blade between the layers to separate it. The cutter blade does not enter between the layers, and does not peel off, "◎", the cutter blade enters the interlayer, can make the peeled portion, but from what can not be peeled continuously from "○", The cutter blade entered between the layers and continuously peeled from the peeled portion was designated as “x”.

[Synthesis Example 1] Synthesis of Cyclic Olefin Resin (A1) 8-Methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
215 parts of 3-dodecene, 35 parts of bicyclo [2.2.1] hept-2-ene, 18 parts of 1-hexene (molecular weight regulator) and 750 parts of toluene (solvent for ring-opening polymerization reaction) The reaction vessel was purged with nitrogen, and this 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. = 0.35 mol: 0.3 mol: 1 mol) of toluene solution (concentration: 0.05 mol / l) was added to 3.7 parts, and this solution was heated and stirred at 80 ° C. for 3 hours to open the ring. Polymerization reaction was performed to obtain a ring-opening polymer solution. The polymerization conversion rate in this polymerization reaction was 97%, and the obtained ring-opening 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. The reaction solution was poured into a large amount of methanol to separate and recover the coagulated product, which was dried to obtain a hydrogenated polymer (hereinafter referred to as cyclic olefin resin (A1)).

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

[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 ^7,10 ] -3-dodecene (46 parts) and tricyclo [
4.3.0.1 ^2,5 ] -deca-3,7-diene and 66 parts of 1-hexene (molecular weight regulator) and toluene as a solvent for the ring-opening polymerization reaction. A hydrogenated polymer (hereinafter referred to as cyclic olefin resin (A2)) was obtained in the same manner as in Synthesis Example 1 except that cyclohexane was used instead of.

  The obtained resin A2 has a hydrogenation rate of 99.9%, a glass transition temperature (Tg) of 125 ° C., an Mn of 30,000, an Mw of 122,000, a molecular weight distribution (Mw / Mn) of 4.07, The logarithmic viscosity was 0.63 dl / g.

[Synthesis Example 3] Synthesis of vinyl aromatic resin (B1) In a glass flask equipped with a stirrer, a condenser and a thermometer, 127.87 g (1.23 mol) of styrene, 13.33 g (0.136 mol) of maleic anhydride, Toluene 75 g as a solvent and 1,1′-azobis (cyclohexane-1-carbonitrile) 0.67 g (2.7 mmol) as a radical initiator were added, heated to 90 ° C., and reacted for 15 hours. A part of this polymerization solution was taken out and the reaction rate was measured to be 85%. Moreover, it was Mw = 129,900 and Mw / Mn = 2.00 when the molecular weight was measured.

The obtained polymerization reaction solution was diluted with tetrahydrofuran and coagulated in a large amount of methanol to recover and purify the polymer, followed by drying for 2 days in an 80 ° C. vacuum dryer. When the molecular weight and logarithmic viscosity of the obtained polymer were measured, Mw = 131,910 (Mw / Mn
= 1.88), logarithmic viscosity η = 0.44 dL / g, and the yield was 80%. The copolymer composition ratio determined by NMR was as prepared. The obtained polymer was a styrene / maleic anhydride copolymer, and the glass transition temperature was 122 ° C. Hereinafter, the obtained vinyl aromatic copolymer (resin) is referred to as B1.

[Synthesis Example 4] Synthesis of vinyl aromatic resin (B4) 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 polymer were measured, Mw = 168,300 (Mw / Mn = 1.68), logarithmic viscosity η = 0.42 dL / g, and the yield was 87%. The obtained polymer was polystyrene and the glass transition temperature was 102 ° C. Hereinafter, the obtained vinyl aromatic copolymer (resin) is referred to as B4.

[Preparation Example] Preparation of water-based adhesive 250 parts of distilled water was charged into a reaction vessel, 90 parts of butyl acrylate, 8 parts of 2-hydroxyethyl methacrylate, 2 parts of divinylbenzene, and potassium oleate in an amount of 0. 1 part was added, and this was stirred with a stirring blade made of Teflon (registered trademark) and dispersed. After 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 Substrate Film (FA1) Cyclic olefin resin A1 obtained in Synthesis Example 1 was dissolved in dichloromethane to a concentration of 30%, and pentaerythrityl tetrakis [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.

This pellet was 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 a coat hanger type die (1700 mm width) was used. It was extruded into a film at 260 ° C and cast into a mirror roll set at 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 resin film roll (FA1) having a width of 1500 mm and a thickness of 150 μm.

[Production Example 2] Production of base film (FA2) Same as Production Example 1 except that the cyclic olefin resin A2 obtained in Synthesis Example 2 was used instead of the cyclic olefin resin (A1) and cyclohexane was used as the solvent. The resin was pelletized and extruded to form a resin film roll (FA2) having a width of 1500 mm and a thickness of 150 μm.

[Production Example 3] 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 4] Production of optical film (negative C plate) and polarizing plate (P0) A base film roll (FA1, 150 μm) of the cyclic olefin resin (A1) obtained in Production Example 1 was stretched at 133 ° C, The film was stretched longitudinally at a stretching ratio of 1.6 times, and then stretched transversely at a stretching temperature of 135 ° C. and a stretching ratio of 2.4 times to obtain an optical film having a thickness of 68 μm. The in-plane retardation R550 of the obtained optical film was 0 to 2 nm, and the average Rth was 190 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. The refractive index in the direction perpendicular to nx in the figure, nz represents the refractive index in the thickness direction of the optical film perpendicular to nx and ny, and d is the film thickness (nm) at the measurement point.
With this optical film, a roll-like film is aligned on one side of the polarizer obtained in Production Example 3, and both are continuously pasted using the aqueous adhesive obtained in Preparation Example, and the other side of the polarizer is adhered. A film made of triacetyl cellulose (hereinafter also referred to as “TAC”) having a thickness of 80 μm was attached to the surface using an adhesive composed of a 5% PVA aqueous solution and dried 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)>
The vinyl aromatic resin (B1) obtained in Synthesis Example 3 was dissolved in methyl ethyl ketone to prepare a coating solution having a resin concentration of 35%. This solution was coated on the base film roll (FA1) obtained in Production Example 1 using a comma coater, dried at 50 ° C. for 10 minutes, 80 ° C. for 10 minutes, and 110 ° C. for 300 minutes, and then the A1 layer An unstretched laminated optical film roll having a configuration of (150 μm) / B1 layer (130 μm) was obtained. The residual solvent amount of this unstretched laminated optical film roll was 1.7%.

This laminated optical film roll was transversely stretched by a tenter at a stretching temperature of 128 ° C. and a draw ratio of 2.0 times to obtain a laminated optical film (F1) having a thickness of 144 μm. The in-plane retardation of the obtained laminated optical film was R450 = 80 nm, R550 = 91 nm, R650 = 97 nm, and NZ = 1.63. 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 3 (the stretching direction that 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 pasted using the water-based adhesive obtained in the preparation example, and the other side of the polarizer has a thickness of 80 μm. The TAC film was stuck using an adhesive composed of a 5% strength PVA aqueous solution and dried to obtain a polarizing plate (P1). When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 42.0% and 99.9%, respectively.

  In order to evaluate the characteristics of this polarizing plate, the polarizing plate and the retardation film attached to the front and back surfaces of the liquid crystal panel of Samsung Electronics Co., Ltd. (model number LN40R81BD) on the viewer side were peeled off and removed. Acrylic transparent adhesive with the negative C plate polarizing plate (P0) obtained in Production Example 4 on the back surface and the polarizing plate (P1) on the front surface, the same as the transmission axis of the polarizing plate originally bonded. Bonding was performed using a 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, the maximum value was 5220 and the minimum value was 110 in all directions and the polar angle range of 0 to 80 degrees, and no unevenness was visually observed. . In the black display state, the color shift was measured at a polar angle of 0 to 60 degrees at an azimuth angle of 45 degrees, and Δu′v ′ = 0.03.

[Example 2]
<Manufacture of laminated optical film (F2)>
As a vinyl aromatic resin (B2) instead of the vinyl aromatic resin (B1), Dairaku D332 (styrene-maleic anhydride copolymer (maleic anhydride content 15%), Tg: 128 ° C.) manufactured by Nova Chemicals In the same manner as in Example 1, an unstretched laminated optical film roll having a structure of A1 layer (150 μm) / B2 layer (120 μm) and a residual solvent amount of 1.5% was obtained. This laminated optical film roll was transversely stretched with a tenter at a stretching temperature of 130 ° C. and a draw ratio of 2.0 times to obtain a laminated optical film (F2) having a thickness of 138 μm. The in-plane retardation of the obtained laminated optical film was R450 = 80 nm, R550 = 90 nm, R650 = 96 nm, and NZ = 1.70. 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. When 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 instead of the polarizing plate (P1), the maximum value was obtained in the range of all directions and polar angles of 0 to 80 degrees. : 5140, minimum value: 95, which is a high numerical value, and no unevenness was visually observed. In the black display state, when the azimuth angle was 45 degrees and the color shift was measured at a polar angle of 0 to 60 degrees, Δu′v ′ = 0.04.
<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 in the same manner as in Example 1 except that the polarizing plate (P2 ′) was used instead of the polarizing plate (P1). Value: 5110, minimum value: 95, which is a high numerical value. No unevenness was visually observed. In the black display state, when the azimuth angle was 45 degrees and the color shift was measured at a polar angle of 0 to 60 degrees, Δu′v ′ = 0.04.

[Example 3]
<Manufacture of laminated optical film (F3)>
Example 1 except that Rurex A14 (styrene-methacrylic acid copolymer, Tg: 129 ° C.) manufactured by DIC Corporation was used as the vinyl aromatic resin (B3) instead of the vinyl aromatic resin (B1). In the same manner as above, an unstretched laminated optical film roll having a structure of A1 layer (150 μm) / B3 layer (110 μm) and a residual solvent amount of 1.4% was obtained. This laminated optical film roll was transversely stretched with a tenter at a stretching temperature of 130 ° C. and a stretching ratio of 2.0 times to obtain a laminated optical film (F3) having a thickness of 133 μm. The in-plane retardation of the obtained laminated optical film was R450 = 83 nm, R550 = 92 nm, R650 = 97 nm, and NZ = 1.68. 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. When the contrast ratio of the liquid crystal television was measured in the same manner as in Example 1 except that the polarizing plate (P3) was used instead of the polarizing plate (P1), the maximum value was obtained in the range of all directions and polar angles of 0 to 80 degrees. : 4980, minimum value: 90, which is a high numerical value, and no unevenness was visually observed. In the black display state, when the azimuth angle was 45 degrees and the color shift was measured at a polar angle of 0 to 60 degrees, Δu′v ′ = 0.04.

[Example 4]
<Manufacture of laminated optical film (F4)>
Other than using base film roll (FA2) instead of base film roll (FA1), and using NOVA CHEMICAL DILARK D332 as vinyl aromatic resin (B2) instead of vinyl aromatic resin (B1) In the same manner as in Example 1, an unstretched laminated optical film roll having a structure of A2 layer (150 μm) / B2 layer (130 μm) and a residual solvent amount of 1.5% was obtained. This laminated optical film roll was transversely stretched with a tenter at a stretching temperature of 130 ° C. and a stretching ratio of 2.0 times to obtain a laminated optical film (F4) having a thickness of 140 μm. The in-plane retardation of the obtained laminated optical film was R450 = 83 nm, R550 = 91 nm, R650 = 96 nm, and NZ = 1.75. When the adhesiveness of this laminated optical film was confirmed, the layers were partially peeled, but the material was destroyed in the middle of peeling.
<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 42.0% and 99.9%, respectively. When 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 instead of the polarizing plate (P1), the maximum value was obtained in the range of all directions and polar angles of 0 to 80 degrees. : 5050, minimum value: 90, which is a high numerical value, and no unevenness was visually observed. In the black display state, when the azimuth angle was 45 degrees and the color shift was measured at a polar angle of 0 to 60 degrees, Δu′v ′ = 0.04.

[Comparative Example 1]
<Manufacture of optical film (F5)>
The substrate film roll (FA1) was used alone, and the tenter was transversely stretched at a stretching temperature of 140 ° C. and a stretching ratio of 3.0 times to obtain an optical film (F5) having a thickness of 55 μm. The in-plane retardation of this optical film was R450 = 121 nm, R550 = 120 nm, R650 = 119 nm, and NZ = 1.33.
<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 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 42.1% and 99.9%, respectively. When the contrast ratio of the liquid crystal television was measured in the same manner as in Example 1 except that the polarizing plate (P5) was used instead of the polarizing plate (P1), the maximum value was obtained in the range of all directions and polar angles of 0 to 80 degrees. : 5160, minimum value: 85, high numerical value, and no unevenness was visually observed. In the black display state, the color shift at the polar angle of 0 to 60 degrees was measured at an azimuth angle of 45 degrees, and Δu′v ′ = 0.11. Since the optical film F5 does not have reverse wavelength dispersion, the Δu′v ′ value is slightly increased, and the color shift is not improved.

[Comparative Example 2]
<Manufacture of laminated optical film (F6)>
The same procedure as in Example 1 was conducted except that the base film roll (FA2) was used instead of the base film roll (FA1), and the vinyl aromatic resin (B4) was used instead of the vinyl aromatic resin (B1). A non-stretched laminated optical film roll having a residual solvent amount of 1.6% was obtained with a constitution of A2 layer (150 μm) / B4 layer (130 μm). This laminated optical film roll was transversely stretched with a tenter at a stretching temperature of 130 ° C. and a stretching ratio of 2.0 times to obtain a laminated optical film (F6) having a thickness of 142 μm. The in-plane retardation of the obtained laminated optical film was R450 = 263 nm, R550 = 260 nm, R650 = 257 nm, and NZ = 1.45. 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 42.0% and 99.9%, respectively. When the contrast ratio of the liquid crystal television was measured in the same manner as in Example 1 except that the polarizing plate (P6) was used instead of the polarizing plate (P1), the maximum value was obtained in the range of all directions and polar angles of 0 to 80 degrees. : 5140, minimum value: 5. 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 ′ = 0.21. The vinyl aromatic resin (B4) used for the laminated optical film (F6) has a low glass transition temperature, and when stretched, the B4 layer does not exhibit a predetermined retardation, and the laminated optical film (F6) is a desirable retardation. However, the contrast ratio in the oblique direction was poor and the color shift was large.

[Comparative Example 3]
<Manufacture of laminated optical film (F7)>
The base film roll (FA1) was stretched in the tenter transverse direction at a stretching temperature of 130 ° C. and a stretching ratio of 2.0 times to obtain an optical film having a thickness of 77 μm. The in-plane retardation of this optical film was R450 = 263 nm, R550 = 260 nm, R650 = 257 nm, and NZ = 1.38.

Subsequently, a polyimide solution for the alignment film is applied on the PET film with a wire bar, dried with hot air at 80 ° C. for 1 minute and further with hot air at 100 ° C. for 2 minutes, and then the surface of the polyimide alignment film is rubbed. did. A polymerizable nematic liquid crystal solution was applied onto the alignment film with a wire bar, dried at 100 ° C. for 2 minutes, and then irradiated with UV at 700 mJ / cm ² using a high pressure mercury lamp to polymerize the polymerizable nematic liquid crystal compound. When this liquid crystal cured film was peeled off from the PET film and the phase difference was measured, R450 = 174 nm, R550 = 165 nm, R650 = 159 nm, NZ = 1.02, and the thickness was 2 μm.

The obtained liquid crystal cured film was bonded onto the optical film using an acrylic transparent adhesive film so that the optical axis directions (in-plane maximum refractive index directions) were orthogonal to each other, and the laminated optical film (F7) was laminated. Obtained. The in-plane retardation of the obtained laminated optical film was R450 = 89 nm, R550 = 95 nm, R650 = 98 nm, and NZ = 3.80.
<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 laminated optical film (F7) was used in place of the laminated optical film (F1) and the liquid crystal cured layer faced the polarizer side. When the single transmittance and polarization degree of the obtained polarizing plate were examined, they were 41.9% and 99.9%, respectively. When the contrast ratio of the liquid crystal television was measured in the same manner as in Example 1 using the polarizing plate (P7) instead of the polarizing plate (P1), the maximum value was 4 in the range of omnidirectional and polar angles of 0 to 80 degrees.
900, minimum value: 15, and no unevenness was visually observed. 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 ′ = 0.15. In the F7 laminated with a liquid crystal cured film, the in-plane retardations R450, R550, and R650 have no problem because they have reverse wavelength dispersion, but the NZ coefficient is not in a desirable range due to an oblique phase difference abnormality. Therefore, although there is no problem with the front contrast ratio, the contrast ratio in the oblique direction is poor and the color shift is large.

  The above results are shown in Table 1 with reference to panel characteristics before peeling off the polarizing plate from the liquid crystal television.

  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 near-infrared cut film used in optical systems such as wave plates and cameras used in optical systems of optical disc recording / reproducing apparatuses.

Claims (7)

On at least one surface of the base film made of either the cyclic olefin resin (A) or the vinyl aromatic resin (B), the base material out of the cyclic olefin resin (A) and the vinyl aromatic resin (B). Laminating a resin that does not constitute a film by a coating method,
Producing a raw film having a cyclic olefin resin (A) layer and a vinyl aromatic resin (B) layer;
A step of uniaxially stretching the obtained raw film in a direction perpendicular to the film longitudinal direction,
The cyclic olefin-based resin (A) comprises a copolymer having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2),
The vinyl aromatic resin (B) is a styrene- (meth) acrylic acid copolymer or a styrene-maleic anhydride copolymer,
The in-plane retardation (R450) at a wavelength of 450 nm, the in-plane retardation at a wavelength of 550 nm (R550), and the in-plane retardation at a wavelength of 650 nm (R650) all satisfy the following formulas (i), (ii), and (iii) A method for producing a laminated optical film, comprising obtaining a laminated optical film that satisfies the requirements.
R450 ≦ R550 ≦ R650 (i)
1.0 ≦ R650 / R550 ≦ 1.2 (ii)
70 nm ≦ R550 ≦ 150 nm (iii)

[In the formula (1), 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 formula: —CH ₂ CH ₂ —. R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing 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 Alternatively, 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. ]

[In Formula (2), Y is a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —, and R ^{5 to} R ⁸ are each independently a hydrogen atom; A halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon; or a polar group, R ⁵ and R ⁶ and / or Alternatively, R ⁷ and R ⁸ may be combined to form a divalent hydrocarbon group, and R ⁵ or R ⁶ and R ⁷ or R ⁸ are 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 difference between the glass transition temperature (Tg (A)) of the cyclic olefin resin (A) and the glass transition temperature (Tg (B)) of the vinyl aromatic resin (B) is within 20 ° C. The method for producing a laminated optical film according to claim 1 . The step of producing the raw fabric film is a step of laminating and forming a vinyl aromatic resin (B) by a coating method on at least one surface of the base film made of the cyclic olefin resin (A). The manufacturing method of the laminated optical film of Claim 1 or 2 . Laminated optical film characterized by being obtained by the process according to any one of claims 1 to 3. The laminated optical film according to claim 4 , wherein the cyclic olefin resin (A) layer and the vinyl aromatic resin (B) layer are directly laminated. 6. A polarizing plate, wherein the laminated optical film according to claim 4 or 5 is laminated on at least one surface of a polarizer via an adhesive or a pressure-sensitive adhesive. 6. A liquid crystal display device, wherein the laminated optical film according to claim 4 or 5 has a polarizing plate laminated on at least one surface of a polarizer via an adhesive or an adhesive.