WO2014171479A1

WO2014171479A1 - Polarizing plate and image display device

Info

Publication number: WO2014171479A1
Application number: PCT/JP2014/060813
Authority: WO
Inventors: 和也久永; 竜二実藤; 隆米本; 裕道古川
Original assignee: 富士フイルム株式会社
Priority date: 2013-04-16
Filing date: 2014-04-16
Publication date: 2014-10-23
Also published as: JP2014206702A; TW201447402A

Abstract

A polarizing plate that contains a first protective film with an Re of at least 3,000 nm bonded to one surface of a polarizer with an adhesive layer (1) interposed therebetween and a second protective film bonded to the other surface of said polarizer with another adhesive layer (2) interposed therebetween, satisfies the inequality E₁ ≠ E₃ and/or the inequality y₁ ≠ y_3,and also satisfies relation (2) makes it possible to: minimize the curling that occurs when a polarizing plate is fabricated by bonding together a polarizer and two protective films using a curable adhesive; and reduce the visibility of rainbow-like unevenness when said polarizing plate is incorporated into a liquid-crystal display (E₁, E₂, and E₃ represent the elastic moduli of the first protective film, the polarizer, and the second protective film, respectively; y₁, y₂, and y₃ represent the thicknesses of the first protective film, the polarizer, and the second protective film, respectively; S₁ and S₂ represent the contractive forces due to the curing of the respective adhesive layers (1 and 2) when said adhesive layers are bonded to the polarizing plate; y is a coordinate that represents the distance from the upper surface of the first protective film in the direction of the polarizer; E(y) represents the elastic modulus of the member at position y; and ∫_y represents an integral taken over the entire thickness of the polarizing plate).

Description

Polarizing plate and image display device

The present invention relates to a polarizing plate and an image display device produced with a curable adhesive.

Image display devices such as liquid crystal display (LCD), plasma display (PDP), electroluminescence display (OELD or IELD), field emission display (FED), touch panel, and electronic paper have a polarizing plate on the display screen side of the image display panel. Has been placed. In general, a polarizing plate has a protective film made of a transparent resin bonded to one side of a polarizer made of polyvinyl alcohol resin via an adhesive, and is also transparent to the other side of the polarizer through an adhesive. It has a structure in which a resin film is bonded as a protective film. The polarizing plate protective film has a protective function against the polarizer, and the protective film on the display surface side is generally provided with functions such as an antireflection function and an ultraviolet absorption function, and the protective film on the liquid crystal cell side. For the purpose of optical compensation and viewing angle compensation of a liquid crystal cell, it may be a so-called retardation film provided with an in-plane and / or thickness direction retardation.

As the protective film on the display side, an example in which a polyester film is used instead of a cellulose acylate film having a small retardation which has been conventionally used is known. For example, in Patent Document 1, a polyester film is used as a protective film on the display side, and a cellulose ester film is used as a protective film on the liquid crystal cell side, and a polarizing plate is produced with an active energy ray-curable adhesive. However, since a polyester film has a large retardation, a polarizing plate produced using a polyester film as a polarizing plate protective film causes rainbow-like unevenness when incorporated in a liquid crystal display device, and from the viewpoint of display performance. It is difficult to use as a protective film on the liquid crystal cell side.

On the other hand, as a polarizing plate protective film with improved rainbow unevenness, the use of a polyester film in which the rainbow unevenness is made difficult to be visually recognized by making the retardation larger than usual by stretching in a uniaxial direction is being studied (Patent Literature). 2).

In recent years, curable adhesives such as active energy ray curable adhesives have been used for bonding protective films to polarizers during the production of polarizing plates. The curable adhesive exhibits an adhesive force between the polarizer film and the protective film by the curing reaction of the adhesive.

JP 2012-137723 A International Publication WO2011 / 162198

However, when the present inventors examined, the polyester film was used as a protective film on one side of the polarizer, and a different type of film was used as the protective film on the other side, and a polarizing plate was prepared using a curable adhesive. It was found that the polarizing plate curls due to the curing shrinkage of the adhesive layer, and then there is a problem that air bubbles and foreign matters enter when pasting to the liquid crystal cell. Further, it was found that the same problem was caused when using a polyester film having a high retardation in the in-plane direction described in Patent Document 2 for eliminating rainbow-like unevenness.

The problem to be solved by the present invention is that a curling which occurs when a polarizing plate is produced by laminating a polarizer and two protective films using a curable adhesive can be suppressed. It is an object of the present invention to provide a polarizing plate in which rainbow-like unevenness is difficult to be visually recognized when incorporated.

As a result of intensive studies by the present inventors in order to solve the above problems, the first protective film is a film that has a large retardation in the in-plane direction and can suppress rainbow unevenness, and the first and second protective films and It has been found that the above-mentioned problems can be solved by controlling the curing shrinkage force at the time of curing of the adhesive layer using the curable adhesive according to the film thickness and elastic modulus value of the polarizer.

That is, the said subject is solved by this invention of the following structures.
[1] A polarizer having polarization performance;
A first protective film bonded to one surface of the polarizer via the adhesive layer 1;
Including a second protective film bonded to the other surface of the polarizer via the adhesive layer 2,
The in-plane direction retardation of the first protective film is 3000 nm or more,
Satisfy at least one of the following formulas (A) and (B),
A polarizing plate satisfying the following formula (2).
E ₁ ≠ E ₃ ... Formula (A)
y ₁ ≠ y ₃ ... Formula (B)

(In the formulas (A), (B), (1) and (2), E ₁ represents the elastic modulus (unit: GPa) of the first protective film, and y ₁ represents the film thickness of the first protective film ( (Unit: μm), E ₂ represents the elastic modulus (unit: GPa) of the polarizer, y ₂ represents the film thickness (unit: μm) of the polarizer, and E ₃ represents the elastic modulus of the second protective film. (Unit: GPa), y ₃ represents the film thickness (unit: μm) of the second protective film, S ₁ represents the curing shrinkage force when the adhesive layer 1 is bonded to the polarizing plate, and S ₂ represents adhesion. It represents the curing shrinkage force at the time of laminating the polarizing plate of layer 2,

Is the integral over the entire film thickness of the polarizing plate, y is the coordinate taken in the direction of the polarizer from the top surface of the first protective film, and E (y) is the elastic modulus (unit: GPa) of the member at that coordinate.
[2] The polarizing plate according to [1] preferably includes an adhesive that allows the adhesive layer 1 and the adhesive layer 2 to be cured by active energy rays.
[3] In the polarizing plate according to [1] or [2], the thickness of the adhesive layer 1 and the adhesive layer 2 is preferably 0.5 to 5 μm.
[4] In the polarizing plate according to any one of [1] to [3], the first protective film preferably contains a polyester resin or a polycarbonate resin as a main component.
[5] In the polarizing plate according to any one of [1] to [4], it is preferable that an easy-adhesion layer and a hard coat layer are disposed on the first protective film.
[6] [1] ~ polarizing plate according to any one of [5] is preferably an elastic modulus _{E 2} of the polarizer is 10 ~ 30 GPa.
[7] A step of bonding a first protective film having an in-plane retardation of 3000 nm or more to one surface of a polarizer having polarizing performance via the adhesive layer 1;
Bonding the second protective film to the other surface of the polarizer via the adhesive layer 2 controlled to have a film thickness different from the adhesive layer 1;
The method for producing a polarizing plate according to any one of [1] to [6], further comprising a step of curing and shrinking the adhesive layer 1 and the adhesive layer 2.
[8] The method for producing a polarizing plate according to [7] includes an adhesive in which the adhesive layer 1 and the adhesive layer 2 are cured by active energy rays,
The step of curing and shrinking the adhesive layer 1 and the adhesive layer 2 is preferably a step of irradiating active energy rays to simultaneously cure the adhesive layer 1 and the adhesive layer 2.
[9] The method for producing a polarizing plate according to [7] or [8] includes an adhesive in which the adhesive layer 1 and the adhesive layer 2 are cured by ultraviolet rays,
The first protective film contains a UV absorber;
The step of curing and shrinking the adhesive layer 1 and the adhesive layer 2 is preferably a step of simultaneously curing the adhesive layer 1 and the adhesive layer 2 by irradiating ultraviolet rays from the second protective film side.
[10] In the method for producing a polarizing plate according to any one of [7] to [9], the compositions of the adhesive layer 1 and the adhesive layer 2 are preferably the same.
[11] An image display device comprising the polarizing plate according to any one of [1] to [6].

According to the present invention, when a polarizing plate is produced by laminating a polarizer and two protective films using a curable adhesive, curling that occurs can be suppressed, and when it is incorporated into a liquid crystal display device A polarizing plate in which rainbow-like unevenness is hardly visible can be provided.

It is the schematic which shows the cross section of an example of the polarizing plate of this invention. It is the schematic which showed the direction of the hardening shrinkage force of the contact bonding layer when producing the polarizing plate of this invention. It is the schematic of the model for description of the method of controlling the hardening shrinkage force of the contact bonding layer in the polarizing plate of this invention. It is the schematic which shows the cross section of an example of the image display apparatus of this invention.

Hereinafter, the polarizing plate and the image display device of the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Polarizer]
The polarizing plate of the present invention includes a polarizer having polarizing performance, a first protective film bonded to one surface of the polarizer via an adhesive layer 1, and an adhesive layer on the other surface of the polarizer. And the second protective film bonded through 2, the retardation in the in-plane direction of the first protective film is 3000 nm or more, and at least one of the following formulas (A) and (B) And satisfying the following formula (2).
E ₁ ≠ E ₃ ... Formula (A)
y ₁ ≠ y ₃ ... Formula (B)

Is the integral over the entire film thickness of the polarizing plate, y is the coordinate taken in the direction of the polarizer from the top surface of the first protective film, and E (y) is the elastic modulus (unit: GPa) of the member at that coordinate.
With such a configuration, the polarizing plate of the present invention has curl (particularly MD direction curling) that occurs when a polarizing plate is produced by laminating a polarizer and two protective films using a curable adhesive. It can be suppressed and rainbow-like unevenness is difficult to be visually recognized when it is incorporated in a liquid crystal display device.
The polarizing plate of the present invention can suppress curl in the MD direction in particular, but there is no particular problem with curl in the TD direction when MD direction curl is completely eliminated.

<Configuration>
First, the structure of the polarizing plate of this invention is demonstrated based on drawing.
A polarizing plate (reference numeral 20 in the figure) of the present invention shown in FIG. 1 includes a polarizer having a polarization performance (reference numeral 2 in the figure), and an adhesive layer 1 (reference numeral in the figure) on one surface of the polarizer. 11) bonded through the first protective film (reference numeral 1 in the figure) and the other surface of the polarizer through the adhesive layer 2 (reference numeral 12 in the figure). And a protective film (reference numeral 3 in the figure).

The polarizing plate of the present invention satisfies at least one of the following formulas (A) and (B).
E ₁ ≠ E ₃ ... Formula (A)
y ₁ ≠ y ₃ ... Formula (B)
That is, in the polarizing plate of the present invention, the elastic modulus of the first protective film and the elastic modulus of the second protective film are not equal, or the film thickness of the first protective film and the film thickness of the second protective film are equal. Absent. In the polarizing plate having such a configuration, the neutral axis, which is the center of gravity position of the polarizing plate described later, is shifted from the central axis in the film thickness direction of the polarizer. Therefore, curling of the polarizing plate is suppressed unless the formula (2) is satisfied. It is hard to do.

Is the integral over the entire film thickness of the polarizing plate, y is the coordinate taken in the direction of the polarizer from the top surface of the first protective film, and E (y) is the elastic modulus (unit: GPa) of the member at that coordinate.

(Detailed description of formulas (1) and (2))
The formulas (1) and (2) will be described. The polarizing plate of the present invention is a laminate of at least 5 layers including at least a first protective film, an adhesive layer 1, a polarizer, an adhesive layer 2, and a second protective film. The curling of the polarizing plate is caused by the shrinkage of the

adhesive layers

1 and 2 when cured, and the size and direction of the curl are the positions of the

adhesive layers

1 and 2 and the neutral axis that is the center of gravity of the polarizing plate. It depends on the relationship.

The expression (1) is an expression that represents the neutral axis position η of the polarizing plate with reference to the surface of the first protective film opposite to the polarizer. The neutral axis position η of the polarizing plate and the bending moment applied to the polarizing plate will be described with reference to FIG. 3 as a model diagram. In FIG. 3, the three-layer laminate of the first protective film, the polarizer, and the second protective film is shown. However, since the contribution to the fluctuation of the neutral axis position η of the

adhesive layers

1 and 2 is small, the three-layer structure is used. Approximated. At this time, Formula (1) is represented by the following (3).

The neutral axis and the distance of the

adhesive layer

1 and 2 respectively _{| η-y 1 |, |} η- (y 1 + y 2 | In prompted, cure shrinkage force _{S 1} when the polarizing plate bonding of the adhesive layer 2 , the bending moment product of S ₂ causes curling polarizing plate.

The expression (2) expresses the ratio of the bending moments in the

adhesive layers

1 and 2 and is cured when the value of the central term of the expression (2) is in the range of 0.5 to 1.8. Curling that occurs when a polarizing plate is produced by laminating a polarizer and two protective films using a mold adhesive can be reduced. Further, the value of the central term in the formula (2) is more preferably in the range of 0.6 to 1.1, and even more preferably 0.7 to 1, using a curable adhesive and a polarizer. Curling that occurs when two protective films are bonded together to produce a polarizing plate is eliminated.

(Other layers)
The polarizing plate of the present invention may have other layers other than the first protective film, the adhesive layer 1, the polarizer, the adhesive layer 2, and the second protective film. As said other layer, an easily bonding layer, a hard-coat layer, and another well-known functional layer can be mentioned. In the polarizing plate of the present invention, it is preferable that an easy-adhesion layer and a hard coat layer are disposed on the first protective film for the purpose of preventing reflection, suppressing glare, and suppressing scratches.
FIG. 4 shows an example of the image display device of the present invention (reference numeral 30 in the drawing) using the polarizing plate of the present invention as a polarizing plate on the viewing side (reference numerals 20 and 21 in the drawing). In the polarizing plate of the present invention shown in FIG. 4, an easy-adhesion layer (reference numeral 14 in the figure) and a hard coat layer (reference numeral 15 in the figure) are arranged on the first protective film (reference numeral 1 in the figure). It is an aspect.

Hereinafter, preferred aspects of each member constituting the polarizing plate of the present invention and the production method thereof will be described.

<Polarizer>
The polarizing plate of the present invention has a polarizer having polarization performance.

As the polarizer, a polarizer produced by a conventionally known method can be used, and a polyvinyl alcohol polarizer is preferable. For example, a film made of a hydrophilic polymer such as polyvinyl alcohol or ethylene-modified polyvinyl alcohol having an ethylene unit content of 1 to 4 mol%, a polymerization degree of 2000 to 4000, and a saponification degree of 99.0 to 99.99 mol%, A film stretched by treatment with a dichroic dye such as the above, or a film oriented by treating a plastic film such as vinyl chloride is used.

Moreover, as a method of obtaining a polarizer film of 10 μm or less by stretching and dyeing in the state of a laminated film in which a polyvinyl alcohol layer is formed on a substrate, Patent No. 5048120, Patent No. 5143918, Patent No. 5048120 No. 4, Patent No. 4691205, Patent No. 4751481 and Patent No. 4751486 can be cited, and known techniques relating to these polarizers can also be preferably used for the polarizing plate of the present invention.

In the polarizing plate of the present invention, the elastic modulus E _{2 in} the absorption axis direction of the polarizer is preferably 10 to 30 GPa, more preferably 15 to 29 GPa, and particularly preferably 15 to 28 GPa.

<First protective film>
The polarizing plate of the present invention includes a first protective film that is bonded to one surface of the polarizer via the adhesive layer 1 and has an in-plane retardation of 3000 nm or more.

(resin)
Although there is no restriction | limiting in particular as a main component of said 1st protective film, In the polarizing plate of this invention, it is preferable that said 1st protective film contains a polyester resin or a polycarbonate resin as a main component.
The first protective film is preferably a film mainly containing a resin such as a polyester resin or a polycarbonate resin, but may be a single layer film mainly containing a resin such as a polyester resin or a polycarbonate resin. Further, it may be a multilayer film having a layer mainly composed of a resin such as a polyester resin or a polycarbonate resin. Moreover, the surface treatment may be performed on both surfaces or one surface of these single layer films or multilayer films, and this surface treatment is performed by corona treatment, saponification treatment, heat treatment, ultraviolet irradiation, electron beam irradiation, or the like. Modification may be sufficient, and thin film formation by application | coating, vapor deposition, etc. of a polymer, a metal, etc. may be sufficient. The mass ratio of the resin such as polyester resin or polycarbonate resin in the entire film is usually 50 mass% or more, preferably 70 mass% or more, more preferably 90 mass% or more.

-Polyester film-
The first protective film preferably contains a polyester resin as a main component.
Examples of the polyester include polyethylene terephthalate, polyethylene isophthalate, polyethylene 2,6-naphthalate, polybutylene terephthalate, and 1,4-cyclohexanedimethylene terephthalate, and two or more of them may be used as necessary. . Of these, polyethylene terephthalate is preferably used.

Polyethylene terephthalate is a polyester having a structural unit derived from terephthalic acid as a dicarboxylic acid component and a structural unit derived from ethylene glycol as a diol component, and 80 mol% or more of all repeating units are preferably ethylene terephthalate. The structural unit derived from other copolymerization components may be included. Other copolymer components include isophthalic acid, p-β-oxyethoxybenzoic acid, 4,4′-dicarboxydiphenyl, 4,4′-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid , Dicarboxylic acid components such as sebacic acid, 5-sodium sulfoisophthalic acid, 1,4-dicarboxycyclohexane, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, bisphenol A ethylene oxide adduct, polyethylene glycol And diol components such as polypropylene glycol and polytetramethylene glycol. These dicarboxylic acid components and diol components can be used in combination of two or more if necessary. In addition, an oxycarboxylic acid such as p-oxybenzoic acid can be used in combination with the carboxylic acid component or diol component. As another copolymer component, a dicarboxylic acid component and / or a diol component containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be used. Polyethylene terephthalate can be produced by a direct polymerization method in which terephthalic acid and ethylene glycol and, if necessary, other dicarboxylic acid and / or other diol are directly reacted, dimethyl ester of terephthalic acid and ethylene glycol, and necessary Depending on the above, any production method such as a so-called transesterification method in which a dimethyl ester of another dicarboxylic acid and / or another diol is transesterified can be applied.

-Polycarbonate resin-
The first protective film preferably contains a polycarbonate resin as a main component.

Known resins can be used. Examples thereof include polycarbonate resins having a bisphenol A skeleton, which are obtained by reacting a dihydroxy component and a carbonate precursor by an interfacial polymerization method or a melt polymerization method. For example, Japanese Patent Application Laid-Open Nos. 2006-277914 and 2006 -106386 and JP-A-2006-284703 can be preferably used. As a commercial item, "Taflon MD1500" (made by Idemitsu Kosan Co., Ltd.) etc. can be used.
You may use those 2 or more types as needed.

(Various additives in the first protective film)
The first protective film may be blended with known additives as necessary. Examples thereof include ultraviolet absorbers, particles, lubricants, antiblocking agents, thermal stabilizers, antioxidants, and antistatic agents. Agents, light resistance agents, impact resistance improvers, lubricants, dyes, pigments and the like. However, since the first protective film generally requires transparency, it is preferable to keep the additive amount to a minimum.

-UV absorber-
The first protective film may contain an ultraviolet absorber in order to prevent the liquid crystal of the liquid crystal display from being deteriorated by ultraviolet rays. The ultraviolet absorber is not particularly limited as long as it is a compound having ultraviolet absorbing ability and can withstand the heat applied in the manufacturing process of the first protective film.

As the ultraviolet absorber, there are an organic ultraviolet absorber and an inorganic ultraviolet absorber, and an organic ultraviolet absorber is preferable from the viewpoint of transparency. Although it does not specifically limit as an organic type ultraviolet absorber, For example, a benzotriazole type, a cyclic imino ester type, a benzophenone type etc. are mentioned. From the viewpoint of durability, benzotriazole and cyclic imino ester are more preferable. It is also possible to use two or more ultraviolet absorbers in combination.

The benzotriazole-based ultraviolet absorber is not limited to the following, and examples thereof include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2 '-Hydroxy-5'-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2'- Hydroxy-5 '-(methacryloyloxyhexyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-3'-tert-butyl-5'-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2 -[2'-hydroxy-5'-tert-butyl-3 '-(methac Royloxyethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2′-hydroxy-5 ′ -(Methacryloyloxyethyl) phenyl] -5-methoxy-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2 '-Hydroxy-5'-(methacryloyloxyethyl) phenyl] -5-tert-butyl-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-nitro-2H -Benzotriazole and the like.

Moreover, as a commercial item, the said benzotriazole type | system | group ultraviolet absorber can be mentioned, for example, If necessary, it can be used as it is disperse | distributed to water using an emulsifier. Other examples of water-based benzotriazole ultraviolet absorbers include New Coat UVA-204W (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.), SE-2538E (trade name, manufactured by Taisei Fine Chemical), and the like.

The cyclic imino ester-based ultraviolet absorber is not limited to the following, and examples thereof include 2-methyl-3,1-benzoxazin-4-one and 2-butyl-3,1-benzoxazine-4. -One, 2-phenyl-3,1-benzoxazin-4-one, 2- (1- or 2-naphthyl) -3,1-benzoxazin-4-one, 2- (4-biphenyl) -3, 1-benzoxazin-4-one, 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2-m-nitrophenyl-3,1-benzoxazin-4-one, 2-p-benzoyl Phenyl-3,1-benzoxazin-4-one, 2-p-methoxyphenyl-3,1-benzoxazin-4-one, 2-o-methoxyphenyl-3,1-benzoxazin-4-one 2-cyclohexyl-3,1-benzoxazin-4-one, 2-p- (or m-) phthalimidophenyl-3,1-benzoxazin-4-one, N-phenyl-4- (3,1-benzo Oxazin-4-one-2-yl) phthalimide, N-benzoyl-4- (3,1-benzoxazin-4-one-2-yl) aniline, N-benzoyl-N-methyl-4- (3,1 -Benzoxazin-4-one-2-yl) aniline, 2- (p- (N-methylcarbonyl) phenyl) -3,1-benzoxazin-4-one, 2,2'-bis (3,1- Benzoxazin-4-one), 2,2′-ethylenebis (3,1-benzoxazin-4-one), 2,2′-tetramethylenebis (3,1-benzoxazin-4-one), 2 , 2'-Deca Tylene bis (3,1-benzoxazin-4-one, 2,2 ′-(1,4-phenylene) bis [4H-3,1-benzoxazin-4-one] [Note that 2,2′-p- Phenylenebis (3,1-benzoxazin-4-one)], 2,2'-m-phenylenebis (3,1-benzoxazin-4-one), 2,2 '-(4,4' -Diphenylene) bis (3,1-benzoxazin-4-one), 2,2 '-(2,6- or 1,5-naphthylene) bis (3,1-benzoxazin-4-one), 2, 2 '-(2-methyl-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2'-(2-nitro-p-phenylene) bis (3,1-benzoxazine-4 -One), 2,2 '-(2-chloro-p-phenylene) bis ( 3,1-benzoxazin-4-one), 2,2 ′-(1,4-cyclohexylene) bis (3,1-benzoxazin-4-one), 1,3,5-tri (3,1 -Benzoxazin-4-one-2-yl) benzene, 1,3,5-tri (3,1-benzoxazin-4-one-2-yl) naphthalene, 2,4,6-tri (3,1 -Benzoxazin-4-one-2-yl) naphthalene, 2,8-dimethyl-4H, 6H-benzo (1,2-d; 5,4-d ') bis (1,3) -oxazine-4, 6-dione, 2,7-dimethyl-4H, 9H-benzo (1,2-d; 4,5-d ′) bis (1,3) -oxazine-4,9-dione, 2,8-diphenyl- 4H, 8H-benzo (1,2-d; 5,4-d ′) bis (1,3) -oxazine-4,6-di 2,7-diphenyl-4H, 9H-benzo (1,2-d; 4,5-d ′) bis (1,3) -oxazine-4,6-dione, 6,6′-bis (2 -Methyl-4H, 3,1-benzoxazin-4-one), 6,6′-bis (2-ethyl-4H, 3,1-benzoxazin-4-one), 6,6′-bis (2 -Phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-methylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-methylenebis (2 -Phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-ethylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-ethylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6 ′ Butylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-butylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′- Oxybis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-oxybis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′- Sulfonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-sulfonylbis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6 '-Carbonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6'-carbonylbis (2-phenyl-4H, 3,1-benzoxazin-4-one), 7 , 7'-methylenebis ( 2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-methylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 7,7′-bis ( 2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-ethylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-oxybis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′-sulfonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7′- Carbonyl bis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,7′-bis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,7 ′ -Bis (2-phenyl-4H, 3,1-benzoxazine- -One, 6,7'-methylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,7'-methylenebis (2-phenyl-4H, 3,1-benzoxazine-4-one) ON).

Among the above compounds, when considering the color tone, a benzoxazinone-based compound which is difficult to be yellowed is preferably used. As an example thereof, a compound represented by the following general formula (1) is more preferably used. It is done.

In the general formula (1), R represents a divalent aromatic hydrocarbon group, and X ¹ and X ² are each independently selected from hydrogen or the following functional group group, but are not necessarily limited thereto. Absent.

Functional group: alkyl group, aryl group, heteroaryl group, halogen, alkoxyl group, aryloxy group, hydroxyl group, carboxyl group, ester group, nitro group.

Among the compounds represented by the general formula (1), 2,2 ′-(1,4-phenylene) bis [4H-3,1-benzoxazin-4-one] is particularly preferable in the present invention.

The amount of the ultraviolet absorber to be contained in the first protective film is usually 10.0% by mass or less, preferably 0.3 to 3.0% by mass. When an ultraviolet absorber in an amount exceeding 10.0% by mass is contained, the ultraviolet absorber may bleed out on the surface, which may cause deterioration of surface functionality such as adhesion deterioration.

Further, in the case of the first protective film having a multilayer structure, it is preferably at least a three-layer structure, and the ultraviolet absorber is preferably blended in the intermediate layer. By blending an ultraviolet absorber in the intermediate layer, the compound can be prevented from bleeding out to the film surface, and as a result, properties such as film adhesion can be maintained.

(Characteristics of the first protective film)
-Phase difference-
The first protective film has an in-plane retardation Re (phase difference value) of 3000 nm or more, preferably 3000 to 30000 nm, more preferably 4000 to 20000 nm, and still more preferably 6000 nm to 15000 nm. is there. By setting the in-plane retardation value to 3000 nm or more, when the polarizing plate of the present invention is incorporated in a liquid crystal display device, rainbow-like unevenness tends to be hardly recognized. When the in-plane retardation value is 30000 nm or less, the film can be thinned, and a film having excellent brittleness and handling properties can be obtained. The in-plane retardation value Re of the first protective film is represented by the following formula (4).

Here, nx is the refractive index in the in-plane slow axis direction of the first protective film, and ny is the in-plane fast axis direction (direction orthogonal to the in-plane slow axis direction) of the first protective film. It is a refractive index, and y ₁ is the thickness of the first protective film.

The retardation Rth in the thickness direction of the first protective film is represented by the following formula (5).

Here, nz is the refractive index in the thickness direction of the first protective film.

The Nz value of the first protective film is preferably 2.0 or less. In addition, Nz value of a 1st protective film is represented by following formula (6).

In this specification, Re, Rth, and Nz at a wavelength λnm can be measured as follows.
Using two polarizing plates, the orientation axis direction of the first protective film was determined, and a 4 cm × 2 cm rectangle was cut out so that the orientation axis directions were orthogonal to each other, and used as a measurement sample. For this sample, the biaxial refractive index (Nx, Ny) perpendicular to each other and the refractive index (Nz) in the thickness direction were determined by an Abbe refractometer (Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm). The absolute value (| Nx−Ny |) of the difference in refractive index between the axes was defined as the anisotropy (ΔNxy) of the refractive index. The thickness y ₁ (nm) of the first protective film was measured using an electric micrometer (manufactured by Fine Reef, Millitron 1245D), and the unit was converted to nm. Measured Nx, Ny, Nz, Re from the value of _{y 1,} Rth, Nz was calculated.

The above Re and Rth are adjusted by the kind of the thermoplastic resin used in the film, the amount of the thermoplastic resin and the additive, the addition of the retardation developer, the film thickness, the stretching direction and the stretching ratio of the film, etc. can do.

-Film thickness-
The thickness of the first protective film is preferably 10 to 200 μm, more preferably 15 to 100 μm, and particularly preferably 20 to 60 μm. When the thickness of the first protective film is 20 μm or more, it tends to be easy to handle, and when the thickness is 100 μm or less, there is a tendency to obtain the merit of manufacturing cost reduction due to thinning.

-Elastic modulus-
The elastic modulus of the first protective film is preferably 1.8 to 8.0 GPa, more preferably 1.8 to 6.0 GPa, and more preferably 1.8 to 5.0 GPa in the MD direction. It is particularly preferable from the viewpoints of production suitability such as curling suppression of the polarizing plate and transportability at the time of film production, end slit property and difficulty of breaking.
Here, the conveyance direction (MD direction, longitudinal direction) of the film is the conveyance direction (MD direction) at the time of film production, and the direction perpendicular to the conveyance direction at the time of film production (TD direction). It is. It is preferable that the conveyance direction (MD direction, longitudinal direction) of a 1st protective film is parallel to the absorption axis of the said polarizer in the polarizing plate of this invention. In addition, the parallel in this specification includes not only a completely parallel mode but also a mode having an optically acceptable angle shift from the completely parallel mode.
The direction perpendicular to the transport direction of the first protective film (TD direction) is preferably the maximum direction of the in-plane elastic modulus of the first protective film. The maximum direction of the in-plane elastic modulus of the protective film is for a film that has been conditioned for 2 hours or more in an atmosphere of 25 ° C. and 60% relative humidity using a sound velocity measuring device “SST-2501, Nomura Corporation”. In an atmosphere of 25 ° C. and a relative humidity of 60%, the speed of sound is measured by dividing the 360 ° direction into 32 parts, and the maximum speed direction can be determined as the maximum direction of the in-plane elastic modulus.

The elastic modulus of the film depends on the type and addition amount of the thermoplastic resin of the first protective film material, the selection of additives (particularly, the particle size, refractive index, and addition amount of the matting agent particles), and film production conditions. (Stretch ratio, etc.) can be adjusted.
For the elastic modulus, a sample having a length of 200 mm in the measurement direction and a width of 10 mm was prepared, and the sample was left in an environment of 60 ° C. and 90% relative humidity for 48 hours, and then left in an environment of 25 ° C. and 60% relative humidity for 48 hours. Immediately after the measurement, a sample shape was measured with a strograph V10-C manufactured by Toyo Seiki, with a width of 10 mm and a length between chucks of 100 mm.
In addition, even if one or both of the polarizer and the first protective film and the second protective film are attached, the polyvinyl alcohol that is the polarizer is softened by soaking in hot water or the like. By removing, it becomes possible to measure the elastic modulus of the film alone.

The MD / TD elastic modulus ratio of the elastic modulus of the first protective film is preferably 0.01 to 0.8. Further, it is more preferably 0.01 to 0.7, and particularly preferably 0.01 to 0.6.

(Method for producing the first protective film)
The first protective film is preferably stretched in the width direction. There is no restriction | limiting in particular as a manufacturing method of a 1st protective film. In order to impart the above properties to the first protective film, it is preferable to produce the first protective film by the following method.
First, a resin used for the first protective film (for example, a polyester resin) is melt-extruded into a film shape, cooled and solidified with a casting drum to form an unstretched film, and if necessary, an easy-adhesion layer is formed. It is preferable to apply a coating solution and stretch this unstretched film at a temperature of Tg to (Tg + 60) ° C. of the polyester film so that it is 3 to 10 times, preferably 3 to 7 times in the width direction. The first protective film is preferably uniaxially stretched in the width direction from the viewpoint of greatly expressing in-plane retardation Re.

Next, it is preferable to perform heat treatment (herein referred to as heat setting) for 1 to 60 seconds at 140 ° C. or higher and 220 ° C. or lower. The heat setting temperature is more preferably 150 ° C. or higher and 220 ° C. or lower, and particularly preferably 150 ° C. or higher and lower than 220 ° C.

Further, it is preferable to perform reheat treatment (referred to as relaxation treatment) while shrinking by 0 to 20% in the longitudinal direction and / or the width direction at a temperature lower by 10 to 20 ° C. than the heat setting temperature. In this method, since the film is less likely to come into contact with the roll, minute scratches and the like are less likely to occur on the film surface than in the method described above, which is advantageous for application to optical applications. The glass transition temperature of the film is expressed as Tg. When the heat setting temperature is 150 ° C. or more and less than 220 ° C., the deviation in the orientation direction of the polyester is reduced and the thermal dimensional change is also reduced, so that the hard coat layer is not easily peeled off or cracked.

<Second protective film>
The polarizing plate of this invention contains the 2nd protective film bonded through the contact bonding layer 2 on the other surface of the side by which the 1st protective film of the polarizer was bonded.

(resin)
Although there is no restriction | limiting in particular as a main component of said 2nd protective film, In the polarizing plate of this invention, it is preferable that said 2nd protective film contains a cycloolefin resin, an acrylic resin, or a cellulose ester resin as a main component.
The second protective film is preferably a film mainly containing a resin such as a cycloolefin resin, an acrylic resin or a cellulose ester resin, but a resin such as a cycloolefin resin, an acrylic resin or a cellulose ester resin is the main component. Or a multilayer film having a layer mainly composed of a resin such as a cycloolefin resin, an acrylic resin, or a cellulose ester resin. Moreover, the surface treatment may be performed on both surfaces or one surface of these single layer films or multilayer films, and this surface treatment is performed by corona treatment, saponification treatment, heat treatment, ultraviolet irradiation, electron beam irradiation, or the like. Modification may be sufficient, and thin film formation by application | coating, vapor deposition, etc. of a polymer, a metal, etc. may be sufficient. The mass ratio of the resin such as cycloolefin resin, acrylic resin, and cellulose ester resin in the entire film is usually 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.

-Cycloolefin resin-
As the thermoplastic resin that can be used in the present invention, a cycloolefin resin (hereinafter also referred to as a cyclic polyolefin resin) can be used. Here, the cyclic polyolefin resin represents a polymer resin having a cyclic olefin structure.
The cyclic polyolefin resins preferably used in the present invention are listed below.
As a polymer having a cyclic olefin structure preferable for the present invention, a cyclic polyolefin resin which is an addition (co) polymer containing at least one repeating unit represented by the following general formula (II) and, if necessary, a general A cyclic polyolefin resin which is an addition (co) polymer further comprising at least one repeating unit represented by formula (I). Further, a ring-opening (co) polymer containing at least one cyclic repeating unit represented by the general formula (III) can also be suitably used.

In the formulas (I) to (III), m represents an integer of 0 to 4. R ¹ to R ⁶ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, X ¹ to X ³ , Y ¹ to Y ³ are hydrogen atoms, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, or a halogen atom. A substituted hydrocarbon group having 1 to 10 carbon atoms, — (CH ₂ ) _n COOR ¹¹ , — (CH ₂ ) _n OCOR ¹² , — (CH ₂ ) _n NCO, — (CH ₂ ) _n NO ₂ , — ( CH ₂ ) _n CN, — (CH ₂ ) _n CONR ¹³ R ¹⁴ , — (CH ₂ ) _n NR ¹³ R ¹⁴ , — (CH ₂ ) _n OZ, — (CH ₂ ) _n W, or X ¹ and Y ¹ Alternatively, (—CO) ₂ O and (—CO) ₂ NR ¹⁵ composed of X ² and Y ² or X ³ and Y ³ are shown. R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ are hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, Z is a hydrocarbon group or a hydrocarbon group substituted with halogen, and W is SiR ¹⁶ _p D _3-p (R ¹⁶ is a hydrocarbon group having 1 to 10 carbon atoms, D is a halogen atom, —OCOR ¹⁶ or —OR ¹⁶ , p is an integer of 0 to 3), n is an integer of 0 to 10 Show.

Norbornene-based polymer hydrides can also be used preferably. As disclosed in Japanese Patent Application Laid-Open No. 2004-309979 or the like, the polycyclic unsaturated compound is hydrogenated after addition polymerization or metathesis ring-opening polymerization. In the norbornene-based polymer used in the present invention, R ⁵ to R ⁶ are preferably a hydrogen atom or —CH ₃ , X ³ and Y ³ are preferably a hydrogen atom, Cl, —COOCH ₃ , and other groups are appropriately selected. The This norbornene resin is sold under the trade name Arton G or Arton F by JSR Co., Ltd., and Zeonor ZF14, ZF16, Zeonex 250 or Zeonex 250 by Nippon Zeon Co., Ltd. They are commercially available under the trade name 280 and can be used.

Furthermore, norbornene-based addition (co) polymers can also be preferably used, and are disclosed in JP-A No. 10-7732, JP-T-2002-504184, US Published Patent No. 200429157157A1 or WO2004 / 070463A1. It can be obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. If necessary, norbornene-based polycyclic unsaturated compounds and ethylene, propylene, butene; conjugated dienes such as butadiene and isoprene; nonconjugated dienes such as ethylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride It is also possible to carry out addition polymerization with linear diene compounds such as acid, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate and vinyl chloride. This norbornene-based addition (co) polymer is marketed by Mitsui Chemicals, Inc. under the name of Apel, and has different glass transition temperatures (Tg) such as APL8008T (Tg70 ° C), APL6013T (Tg125 ° C) or APL6015T ( Grades such as Tg145 ° C). Pellets such as TOPAS 8007, 6013, and 6015 are sold by Polyplastics Co., Ltd. Further, Appear 3000 is sold by Ferrania.

In the present invention, the glass transition temperature (Tg) of the cyclic polyolefin resin is preferably 110 ° C. to 200 ° C., more preferably 115 ° C. to 190 ° C., and further preferably 120 ° C. to 180 ° C.
Further, the weight average molecular weight of the cyclic polyolefin resin is preferably in the range of 50,000 to 500,000.

Production method of film mainly composed of cyclic olefin resin:
About the film which has a cyclic olefin resin as a main component, it can manufacture with the manufacturing method similar to the manufacturing method of the film which has a (meth) acrylic-type polymer as a main component mentioned later, for example, a solution cast method (solution Casting methods), melt extrusion methods, calendering methods, compression molding methods and the like, and conventionally known film forming methods, among which the melt extrusion methods are particularly suitable.

Examples of the melt extrusion method include a T-die method and an inflation method, and the molding temperature at that time may be appropriately adjusted according to the glass transition temperature of the film raw material.
When forming a film by the T-die method, a roll-shaped film can be obtained by attaching a T-die to the tip of a known single-screw extruder or twin-screw extruder and winding the film extruded into a film. it can. At this time, it is possible to perform uniaxial stretching by appropriately adjusting the temperature of the take-up roll and adding stretching in the extrusion direction. Further, simultaneous biaxial stretching, sequential biaxial stretching, and the like can be performed by stretching the film in a direction perpendicular to the extrusion direction.

-acrylic resin-
As the acrylic resin, a known (meth) acrylic resin can be used.
The (meth) acrylic resin is a concept including both a methacrylic resin and an acrylic resin, and includes an acrylate / methacrylate derivative, in particular, an acrylate ester / methacrylate ester (co) polymer.
Furthermore, the (meth) acrylic resin includes a methacrylic resin, an acrylic resin, a (meth) acrylic polymer having a ring structure in the main chain, a polymer having a lactone ring, and a succinic anhydride ring. A maleic anhydride-based polymer having, a polymer having a glutaric anhydride ring, and a glutarimide ring-containing polymer.

(Meth) acrylic polymer:
The repeating structural unit of the (meth) acrylic polymer is not particularly limited. The (meth) acrylic polymer preferably has a repeating structural unit derived from a (meth) acrylic acid ester monomer as a repeating structural unit.

The (meth) acrylic acid ester is not particularly limited, and examples thereof include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and benzyl acrylate. Acrylic acid esters; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate; These may be used alone or in combination of two or more. Among these, methyl methacrylate is particularly preferable from the viewpoint of excellent heat resistance and transparency.
When the (meth) acrylic acid ester is used as a main component, the content ratio in the monomer component to be subjected to the polymerization step is preferably 50 to 100% by mass in order to sufficiently exhibit the effects of the present invention. The amount is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and particularly preferably 90 to 100% by mass.
The glass transition temperature Tg of the resin containing the (meth) acrylic acid ester as a main component is preferably in the range of 80 to 120 ° C.
The weight average molecular weight of the resin mainly composed of (meth) acrylic acid ester is preferably in the range of 50,000 to 500,000.

In order to improve flexibility and handling properties, rubber elastic particles are preferably blended with the (meth) acrylic resin. The rubber elastic particle is a particle containing a rubber elastic body, and may be a particle made of only a rubber elastic body, or may be a multi-layered particle having a rubber elastic body layer, and may be a film surface. From the viewpoint of hardness, light resistance and transparency, an acrylic elastic polymer is preferably used.

Rubber elastic particles containing an acrylic elastic polymer can be obtained with reference to JP 2012-180422 A, JP 2012-032773 A, and JP 2012-180423 A.

The number average particle diameter of the rubber elastic particles is preferably in the range of 10 to 300 nm, more preferably in the range of 50 to 250 nm.

In the (meth) acrylic resin composition forming the (meth) acrylic resin film, 25 to 45% by mass of rubber elastic particles having a number average particle diameter of 10 to 300 nm are blended in a transparent acrylic resin. preferable.

(Meth) acrylic polymer having a ring structure in the main chain:
Among (meth) acrylic polymers, those having a ring structure in the main chain are preferred. By introducing a ring structure into the main chain, the rigidity of the main chain can be improved and the heat resistance can be improved.
In the present invention, among (meth) acrylic polymers having a ring structure in the main chain, a polymer having a lactone ring structure in the main chain, a maleic anhydride polymer having a succinic anhydride ring in the main chain, It is preferably either a polymer having a glutaric anhydride ring structure or a polymer having a glutarimide ring structure in the main chain. Among them, a polymer having a lactone ring structure in the main chain and a polymer having a glutarimide ring structure in the main chain are more preferable.
The following polymers having a ring structure in these main chains will be described in order.

(1) A (meth) acrylic polymer having a lactone ring structure in the main chain A (meth) acrylic polymer having a lactone ring structure in the main chain (hereinafter also referred to as a lactone ring-containing polymer) has a lactone ring in the main chain. Although it will not specifically limit if it is a (meth) acrylic-type polymer which has this, Preferably it has a lactone ring structure shown by the following general formula (100).

General formula (100):

In general formula (100), R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. .
Here, the organic residue having 1 to 20 carbon atoms is preferably a methyl group, an ethyl group, an isopropyl group, an n-butyl group, a t-butyl group, or the like.

The content of the lactone ring structure represented by the general formula (100) in the structure of the lactone ring-containing polymer is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass. %, Particularly preferably 10 to 50% by weight. By setting the content ratio of the lactone ring structure to 5% by mass or more, the heat resistance and surface hardness of the obtained polymer tend to be improved, and by setting the content ratio of the lactone ring structure to 90% by mass or less. The moldability of the obtained polymer tends to be improved.

The content ratio of the lactone ring structure can be calculated from the following formula.
Lactone ring content (% by mass) = B × A × M _R / M _m
(Wherein, B is the mass proportion in the monomer composition used in the copolymerization raw monomer having a structure (hydroxyl group) responsible for the lactonization, M _R lactone ring structure to generate The unit formula weight, M _m is the molecular weight of the raw material monomer having a structure (hydroxyl group) involved in lactone cyclization, and A is the lactone cyclization rate)
In addition, when the cyclization reaction involves a dealcoholization reaction, for example, the lactone cyclization rate can be determined by removing the theoretical weight reduction amount from 150 ° C. before the weight reduction starts to 300 ° C. before the polymer decomposition starts. It can be calculated from the weight loss heating weight loss rate due to the alcohol reaction.

The method for producing the (meth) acrylic resin having a lactone ring structure is not particularly limited. Preferably, the (meth) acrylic resin having a lactone ring structure is obtained by polymerizing the following predetermined monomer to obtain a polymer (p) having a hydroxyl group and an ester group in the molecular chain. The obtained polymer (p) is heat-treated at a temperature in the range of 75 ° C. to 120 ° C. to obtain lactone cyclization condensation for introducing a lactone ring structure into the polymer.
In the polymerization step, a polymer having a hydroxyl group and an ester group in the molecular chain is obtained by conducting a polymerization reaction of a monomer component containing a monomer represented by the following general formula (101).
Formula (101):

(Wherein R ¹ and R ² each independently represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms)

Examples of the monomer represented by the general formula (101) include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, 2- ( Hydroxymethyl) normal butyl acrylate, t-butyl 2- (hydroxymethyl) acrylate, and the like. Among these, methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate are preferred, and methyl 2- (hydroxymethyl) acrylate is particularly preferred from the viewpoint of high heat resistance improvement effect. As for the monomer represented by the general formula (101), only one type may be used, or two or more types may be used in combination.

The content ratio of the monomer represented by the general formula (101) in the monomer component used in the polymerization step has a lower limit value in a preferable range in terms of heat resistance, solvent resistance, and surface hardness, and was obtained. From the viewpoint of moldability of the polymer, there is an upper limit value in a preferable range. In view of these viewpoints, it is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, still more preferably 10 to 60% by mass, and particularly preferably. Is 10 to 50% by mass.

The monomer component provided in the polymerization step may contain a monomer other than the monomer represented by the general formula (101). Although it does not specifically limit as such a monomer, For example, (meth) acrylic acid ester, a hydroxyl-containing monomer, and unsaturated carboxylic acid are mentioned preferably. Only one type of monomer other than the monomer represented by formula (101) may be used, or two or more types may be used in combination.

The weight average molecular weight of the lactone ring-containing polymer is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,000,000, and particularly preferably 50,000 to 500,000.

The lactone ring-containing polymer has a mass reduction rate in the range of 150 to 300 ° C. in dynamic TG measurement, preferably 1% or less, more preferably 0.5% or less, and still more preferably 0.3% or less. It is good. As a method for measuring dynamic TG, the method described in JP-A-2002-138106 can be used.

Since the lactone ring-containing polymer has a high cyclization condensation reaction rate, there is little dealcoholization reaction in the production process of the molded product, and bubbles and silver stripes (silver streaks) are formed in the molded product after molding due to the alcohol. The disadvantage of entering can be avoided. Furthermore, since the lactone ring structure is sufficiently introduced into the polymer due to a high cyclization condensation reaction rate, the obtained lactone ring-containing polymer has high heat resistance.

The lactone ring-containing polymer has a coloring degree (YI) of preferably 6 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less when a chloroform solution having a concentration of 15% by mass is used. . If the degree of coloring (YI) is 6 or less, problems such as loss of transparency due to coloring are unlikely to occur, and therefore, it can be preferably used in the present invention.

The lactone ring-containing polymer has a 5% mass reduction temperature in thermal mass spectrometry (TG) of preferably 330 ° C. or higher, more preferably 350 ° C. or higher, and further preferably 360 ° C. or higher. The 5% mass reduction temperature in thermal mass spectrometry (TG) is an indicator of thermal stability, and by setting it to 330 ° C. or higher, sufficient thermal stability tends to be exhibited. The thermal mass spectrometry can use the apparatus for measuring the dynamic TG.

The glass transition temperature (Tg) of the lactone ring-containing polymer is preferably 115 ° C to 180 ° C, more preferably 120 ° C to 170 ° C, and still more preferably 125 ° C to 160 ° C.

(2) Maleic anhydride-based polymer having a succinic anhydride ring in the main chain A succinic anhydride structure is formed in the main chain in the molecular chain of the polymer (in the main skeleton of the polymer). The acrylic resin is preferably given high heat resistance and has a high glass transition temperature (Tg).
The glass transition temperature (Tg) of the maleic anhydride polymer having a succinic anhydride ring in the main chain is preferably 110 ° C. to 160 ° C., more preferably 115 ° C. to 160 ° C., and further preferably 120 ° C. to 160 ° C. is there.
The weight average molecular weight of the maleic anhydride polymer having a succinic anhydride ring in the main chain is preferably in the range of 50,000 to 500,000.

The maleic anhydride unit used for copolymerization with the acrylic resin is not particularly limited, but JP-A-2008-216586, JP-A-2009-052021, JP-A-2009-196151, JP-T-2012-504783. Mention may be made of maleic acid-modified resins described in the respective publications.
In addition, these do not limit this invention.
As a commercially available maleic acid-modified resin, Delpet 980N manufactured by Asahi Kasei Chemicals Corporation, which is a maleic acid-modified MAS resin (methyl methacrylate-acrylonitrile-styrene copolymer), can be preferably used.
In addition, a method for producing an acrylic resin containing a maleic anhydride unit is not particularly limited, and a known method can be used.

The maleic acid-modified resin is not limited as long as the resulting polymer contains maleic anhydride units, and examples thereof include (anhydrous) maleic acid-modified MS resin, (anhydrous) maleic acid-modified MAS resin (methacrylic acid). Methyl-acrylonitrile-styrene copolymer), (anhydrous) maleic acid modified MBS resin, (anhydrous) maleic acid modified AS resin, (anhydrous) maleic acid modified AA resin, (anhydrous) maleic acid modified ABS resin, ethylene-maleic anhydride Examples include acid copolymers, ethylene- (meth) acrylic acid-maleic anhydride copolymers, and maleic anhydride grafted polypropylene.

The maleic anhydride unit has a structure represented by the following general formula (200).
General formula (200):

In the general formula (200), R ²¹ and R ²² each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms.
The organic residue is not particularly limited as long as it has 1 to 20 carbon atoms. For example, a linear or branched alkyl group, a linear or branched alkylene group, an aryl group, an —OAc group , -CN group and the like. The organic residue may contain an oxygen atom. Ac represents an acetyl group.
R ²¹ and R ²² preferably have 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms.

When each of R ²¹ and R ²² represents a hydrogen atom, it is preferable that other copolymerization components are further included from the viewpoint of adjusting the intrinsic birefringence. As such a ternary or higher heat-resistant acrylic resin, for example, methyl methacrylate-maleic anhydride-styrene copolymer can be preferably used.

(3) Polymer having a glutaric anhydride ring structure in the main chain The polymer having a glutaric anhydride ring structure in the main chain is a polymer having a glutaric anhydride unit.

The polymer having a glutaric anhydride unit preferably has a glutaric anhydride unit represented by the following general formula (300) (hereinafter referred to as a glutaric anhydride unit).

General formula (300):

In general formula (300), R ³¹ and R ³² each independently represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom. R ³¹ and R ³² particularly preferably represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.

The polymer having a glutaric anhydride unit is preferably a (meth) acrylic polymer containing a glutaric anhydride unit. The (meth) acrylic polymer preferably has a glass transition temperature (Tg) of 120 ° C. or higher from the viewpoint of heat resistance.
The glass transition temperature (Tg) of the polymer having a glutaric anhydride ring structure in the main chain is preferably 110 ° C. to 160 ° C., more preferably 115 ° C. to 160 ° C., and further preferably 120 ° C. to 160 ° C.
The weight average molecular weight of the polymer having a glutaric anhydride ring structure in the main chain is preferably in the range of 50,000 to 500,000.

The content of glutaric anhydride units relative to the (meth) acrylic polymer is preferably 5 to 50% by mass, more preferably 10 to 45% by mass. When the content is 5% by mass or more, more preferably 10% by mass or more, an effect of improving heat resistance can be obtained, and further an effect of improving weather resistance can be obtained.

(4) (Meth) acrylic polymer having a glutarimide ring structure in the main chain (meth) acrylic polymer having a glutarimide ring structure in the main chain (hereinafter also referred to as glutarimide resin) By having an imide ring structure, a desirable balance of properties can be expressed in terms of optical properties and heat resistance. The (meth) acrylic polymer having a glutarimide ring structure in the main chain is at least the following general formula (400):

Formula (400):

Wherein R ³⁰¹ , R ³⁰² , and R ³⁰³ are independently hydrogen or an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, or an aryl group. It is preferable to contain a glutarimide resin having 20% by mass or more.

As a preferable glutarimide unit constituting the glutarimide resin used in the present invention, R ³⁰¹ and R ³⁰² are hydrogen or a methyl group, and R ³⁰³ is a methyl group or a cyclohexyl group. The glutarimide unit may be a single type or may include a plurality of types in which R ³⁰¹ , R ³⁰² , and R ³⁰³ are different.

The preferred second structural unit constituting the glutarimide resin used in the present invention is a unit composed of an acrylate ester or a methacrylate ester. Preferable acrylic acid ester or methacrylic acid ester structural unit includes methyl acrylate, ethyl acrylate, methyl methacrylate, methyl methacrylate and the like. Another preferred imidizable unit includes N-alkylmethacrylamide such as N-methylmethacrylamide and N-ethylmethacrylamide. These second structural units may be of a single type or may include a plurality of types.

The content of the glutarimide unit represented by the general formula (400) in the glutarimide resin is 20% by mass or more based on the total repeating unit of the glutarimide resin. The preferred content of the glutarimide unit is 20% to 95% by mass, more preferably 50 to 90% by mass, and still more preferably 60 to 80% by mass. When a glutarimide unit is smaller than this range, the heat resistance of the film obtained may be insufficient, or transparency may be impaired. On the other hand, if it exceeds this range, the heat resistance is unnecessarily increased and it becomes difficult to form a film, the mechanical strength of the resulting film becomes extremely brittle, and the transparency may be impaired.

The glutarimide resin may be further copolymerized with a third structural unit, if necessary. Preferred examples of the third structural unit include styrene monomers such as styrene, substituted styrene and α-methylstyrene, acrylic monomers such as butyl acrylate, and nitrile monomers such as acrylonitrile and methacrylonitrile. Further, a structural unit obtained by copolymerizing maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide and the like can be used. These may be directly copolymerized with the glutarimide unit and the imidizable unit in the glutarimide resin, and graft copolymerized with the resin having the glutarimide unit and the imidizable unit. It may be polymerized. When the third component is added, the content in the glutarimide resin is preferably 5 mol% or more and 30 mol% or less based on the total repeating units in the glutarimide resin.

The glutarimide resin is described in US Pat. No. 3,284,425, US Pat. No. 4,246,374, JP-A-2-153904, and the like, and is obtained by using methyl methacrylate as a main raw material as a resin having an imidizable unit. It can be obtained by using a resin and imidizing the resin having an imidizable unit with ammonia or a substituted amine. When obtaining a glutarimide resin, a unit composed of acrylic acid, methacrylic acid, or an anhydride thereof may be introduced into the glutarimide resin as a reaction by-product. The presence of such a structural unit, particularly an acid anhydride, is not preferable because it reduces the total light transmittance and haze of the obtained film of the present invention. The acrylic acid or methacrylic acid content is 0.5 milliequivalent or less per gram of resin, preferably 0.3 milliequivalent or less, more preferably 0.1 milliequivalent or less. Further, as seen in JP-A No. 02-153904, it is also possible to obtain a glutarimide resin by imidization using a resin mainly composed of N-methylacrylamide and methacrylic acid methyl ester.

The glass transition temperature (Tg) of the glutaric resin is preferably 110 ° C. to 160 ° C., more preferably 115 ° C. to 160 ° C., and further preferably 120 ° C. to 160 ° C.
The weight average molecular weight of the glutar resin is preferably in the range of 50,000 to 500,000.

Manufacturing method of film mainly composed of (meth) acrylic polymer:
Hereinafter, a manufacturing method for forming a film containing a (meth) acrylic polymer as a main component will be described in detail.
In order to form a film using a (meth) acrylic polymer as a main component, for example, a film raw material is pre-blended with a conventionally known mixer such as an omni mixer, and then the obtained mixture is extruded and kneaded. In this case, the mixer used for extrusion kneading is not particularly limited. For example, a conventionally known mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader can be used. .

Examples of the film forming method include conventionally known film forming methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Of these film forming methods, the melt extrusion method is particularly suitable.

Examples of the melt extrusion method include a T-die method and an inflation method, and the molding temperature at that time may be appropriately adjusted according to the glass transition temperature of the film raw material, and is not particularly limited. For example, the temperature is preferably 150 ° C to 350 ° C, more preferably 200 ° C to 300 ° C.

When forming a film by the T-die method, a roll-shaped film can be obtained by attaching a T-die to the tip of a known single-screw extruder or twin-screw extruder and winding the film extruded into a film. it can. At this time, it is possible to perform uniaxial stretching by appropriately adjusting the temperature of the take-up roll and adding stretching in the extrusion direction. Further, simultaneous biaxial stretching, sequential biaxial stretching, and the like can be performed by stretching the film in a direction perpendicular to the extrusion direction.

The film mainly composed of (meth) acrylic polymer may be either an unstretched film or a stretched film. In the case of a stretched film, either a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved. When the (meth) acrylic polymer is a (meth) acrylic polymer having a cyclic structure in the main chain, mixing with other thermoplastic resins increases the retardation even when stretched. It is possible to obtain a film that can be suppressed and retains optical isotropy.

-Cellulose ester resin-
Hereinafter, the cellulose ester resin (preferably cellulose acylate) that can be used for the second protective film will be described in detail.
The degree of substitution of cellulose acylate means the ratio of acylation of three hydroxyl groups present in the structural unit of cellulose (glucose having a (β) 1,4-glycoside bond). The degree of substitution (acylation degree) can be calculated by measuring the amount of bound fatty acid per unit mass of cellulose. In the present invention, the substitution degree of the cellulose body is determined from the peak intensity ratio of the carbonyl carbon in the acyl group by dissolving the cellulose body in a solvent such as dimethyl sulfoxide substituted with deuterium and measuring the 13C-NMR spectrum. Can be calculated. This can be determined by 13C-NMR measurement after substituting the remaining hydroxyl group of cellulose acylate with another acyl group different from the acyl group of cellulose acylate itself. Details of the measurement method are described in Tezuka et al. (Carbohydrate. Res., 273 (1995) 83-91).

The total acyl substitution degree of the cellulose acylate is preferably 2.0 to 2.97, more preferably 2.2 to 2.95, and particularly preferably 2.3 to 2.95.
As the acyl group of cellulose acylate, an acetyl group, a propionyl group, and a butyryl group are particularly preferable, and an acetyl group is particularly preferable.

A mixed fatty acid ester composed of two or more kinds of acyl groups can also be preferably used as the cellulose acylate in the present invention. Also in this case, the acyl group is preferably an acetyl group and an acyl group having 3 to 4 carbon atoms. Moreover, when using mixed fatty acid ester, the substitution degree of an acetyl group is preferably less than 2.5, and more preferably less than 1.9. On the other hand, the substitution degree of the acyl group having 3 to 4 carbon atoms is preferably 0.1 to 1.5, more preferably 0.2 to 1.2, and 0.5 to 1.1. It is particularly preferred.
In the present invention, two types of cellulose acylates having different substituents and / or degree of substitution may be used in combination, mixed, or from a plurality of layers composed of different cellulose acylates by the co-casting method described later. A film may be formed.

Furthermore, mixed acid esters having a fatty acid acyl group and a substituted or unsubstituted aromatic acyl group described in [0023] to [0038] of JP-A-2008-20896 can also be preferably used in the present invention.

The cellulose acylate preferably has a weight average degree of polymerization of 250 to 800, more preferably 300 to 600.
The cellulose acylate preferably has a number average molecular weight of 70000 to 230,000, more preferably a number average molecular weight of 75000 to 230,000, and most preferably a number average molecular weight of 78000 to 120,000.

Cellulose acylate can be synthesized using an acid anhydride or acid chloride as an acylating agent. When the acylating agent is an acid anhydride, an organic acid (for example, acetic acid) or methylene chloride is used as a reaction solvent. Further, a protic catalyst such as sulfuric acid can be used as the catalyst. When the acylating agent is an acid chloride, a basic compound can be used as a catalyst. In the most common synthetic method in the industry, cellulose is an organic acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, butyric acid) or their acid anhydrides (acetic anhydride, propionic anhydride, butyric anhydride). A cellulose ester is synthesized by esterification with a mixed organic acid component containing.

In the above method, cellulose such as cotton linter or wood pulp is activated with an organic acid such as acetic acid and then esterified using a mixture of organic acid components as described above in the presence of a sulfuric acid catalyst. In many cases. The organic acid anhydride component is generally used in an excess amount relative to the amount of hydroxyl groups present in the cellulose. In this esterification treatment, a hydrolysis reaction (depolymerization reaction) of the cellulose main chain (β) 1,4-glycoside bond) proceeds in addition to the esterification reaction. When the hydrolysis reaction of the main chain proceeds, the degree of polymerization of the cellulose ester is lowered, and the physical properties of the cellulose ester film to be produced are lowered. Therefore, the reaction conditions such as the reaction temperature are preferably determined in consideration of the degree of polymerization and molecular weight of the resulting cellulose ester.

(Various additives for the second protective film)
The 2nd protective film may contain the well-known additive used for an organic acid and another polarizing plate protective film, unless it is contrary to the meaning of this invention. The molecular weight of the additive is not particularly limited, but the additives described below can be preferably used.
Additives can be used to control humidity dimensional change rate, improve film thermal properties, optical properties, mechanical properties, impart flexibility, impart water resistance, reduce moisture permeability, etc. It shows a useful effect.

For example, the control of mechanical properties includes the addition of a plasticizer to a film. Examples of plasticizers that can be used as reference include various known esters such as phosphate esters, citrate esters, trimellitic acid esters, and sugar esters. Reference can be made to the description of ester plasticizers and polyester polymers in paragraph numbers 0042 to 0068 of International Publication No. 2011/102492.

In addition, as control of optical properties, for the provision of ultraviolet and infrared absorbing ability, the description of paragraph numbers 0069 to 0072 of International Publication No. 2011/102492 can be referred to, and adjustment of the retardation of the film In addition, a known retardation adjusting agent can be used for controlling expression. The molecular weight of the additive is not particularly limited, but the additives described below can be preferably used.

(Characteristics of the second protective film)
-Film thickness-
The thickness of the second protective film is preferably 10 to 200 μm, more preferably 15 to 100 μm, and particularly preferably 20 to 60 μm. When the thickness of the second protective film is 20 μm or more, it tends to be easy to handle, and when the thickness is 100 μm or less, there is a tendency to obtain the merit of manufacturing cost reduction due to thinning.
In addition, when the thickness of the second protective film is as thin as 60 μm (preferably 40 μm or less, for example, 10 to 40 μm), the effects of the present invention are particularly remarkable. Specifically, the thicker the second protective film is, the more the curable adhesive is used even when a film (polyester film or the like) having a high in-plane retardation is used as the first protective film. Thus, when a polarizing plate is produced by laminating a polarizer and two protective films, curling (positive curling toward the first protective film) tends not to occur. Conversely, when the thickness of the second protective film is 40 μm or less, curling is very likely to occur when a polarizing plate is produced by laminating a polarizer and two protective films using a curable adhesive. Therefore, the curl suppressing effect of the present invention can be remarkably obtained.

-Elastic modulus-
The elastic modulus of the second protective film is preferably 1.8 to 8.0 GPa in the MD direction, more preferably 1.8 to 6.0 GPa, and 1.8 to 5.0 GPa. It is particularly preferable from the viewpoints of production suitability such as curling suppression of the polarizing plate and transportability at the time of film production, end slit property and difficulty of breaking.
In the polarizing plate of the present invention, the transport direction (MD direction, longitudinal direction) of the second protective film is preferably parallel to the absorption axis of the polarizer.

<Adhesive layer>
In the polarizing plate of the present invention, the polarizer and the first protective film are bonded via the adhesive layer 1, and the polarizer and the second protective film are bonded via the adhesive layer 2. The adhesive layer 1 and the adhesive layer 2 preferably contain a curable adhesive.

(Adhesive layer properties)
-Film thickness-
In the polarizing plate of the present invention, the thicknesses of the adhesive layer 1 and the adhesive layer 2 are preferably set to predetermined values in the range of 0.5 to 5 μm. When the thickness of the adhesive layer 1 and the adhesive layer 2 is 0.5 μm or more, unevenness in adhesive strength is unlikely to occur. On the other hand, when the thickness is 5 μm or less, the manufacturing cost can be reduced. If the thickness is relatively thick within this range, for example, 3.5 μm or more, especially 4 μm or more, even if the film thickness of the adhesive layer 1 and the adhesive layer 2 fluctuates somewhat, defects such as bubbles due to the film hardly appear. On the other hand, since increasing the thickness in this way may lead to an increase in cost, it is desired to reduce the thickness as much as possible. For these reasons, the preferable thicknesses of the adhesive layer 1 and the adhesive layer 2 are in the range of 1 to 4 μm, and more preferably in the range of 1.5 to 3.5 μm.

In the polarizing plate of the present invention, the adhesive layer 1 and the adhesive layer 2 are different in film thickness so that the adhesive layer 1 and the adhesive layer 2 satisfy the above formula (2) when the compositions of the adhesive layer 1 and the adhesive layer 2 are the same. From the viewpoint that the curing shrinkage force of the adhesive layer 2 can be controlled, it is preferable.
The preferred range of the ratio of the film thickness of the adhesive layer 1 (hereinafter referred to as “d _1” ) to the film thickness of the adhesive layer 2 (hereinafter referred to as “d _2” ) (that is, d ₁ / d ₂ ) is that of the adhesive layer 1 described later. the cure shrinkage force S ₁ at the time of the polarizing plate bonding, the same as the preferred range of the ratio of hardening shrinkage force S ₂ when the polarizing plate bonding of the adhesive layer 2 (i.e., _S 1 _/ S _2).

-Ratio of curing shrinkage of adhesive layers 1 and 2-
A preferable range of the ratio of the curing shrinkage force S ₁ when the adhesive layer ₁ is bonded to the polarizing plate to the curing shrinkage force S ₂ when the adhesive layer 2 is bonded to the polarizing plate (that is, S ₁ / S ₂ ) is 0. It is preferably 3 to 10 N / m, more preferably 0.4 to 9 N / m, and particularly preferably 0.5 to 8 N / m. Within this range, the curl suppressing effect of the present invention can be remarkably obtained.
In this invention, the shrinkage | contraction force at the time of polarizing plate bonding of the adhesive layer 1 and the adhesive layer 2 is calculated | required by the method as described in the below-mentioned Example. However, the curing shrinkage force when the

adhesive layers

1 and 2 are bonded to the polarizing plate is different from the cured adhesive layer 1 and the adhesive layer 2 in the polarizing plate of the present invention from the composition and film of the adhesive layer 1 and the adhesive layer 2. It can also be determined based on thickness.

(Active energy ray-curable adhesive)
As long as the adhesive is curable, it can be any of those conventionally used in the production of polarizing plates. From the viewpoint of weather resistance, polymerizability, and the like, the adhesive layer 1 and the adhesive layer 2 are It is preferable to include an adhesive that is cured by active energy rays. In addition, the aspect which the adhesive agent changed into the hardened | cured material of the adhesive agent from which a structure differs by the hardening reaction is also contained in the aspect in which the adhesive layer 1 and the adhesive layer 2 contain an adhesive agent. For example, in the adhesive layer 1 and the adhesive layer 2, the case where the adhesive cured by the active energy ray is completely cured and the structure is changed to a cured product of an adhesive having a different structure is also included in the present invention.
Among adhesives that are cured by active energy rays, cationically polymerizable compounds such as epoxy compounds, more specifically, epoxy having no aromatic ring in the molecule as described in JP-A-2004-245925 An active energy ray curable adhesive containing a compound as one of the active energy ray curable components is preferred. Such an epoxy compound is, for example, a hydrogenated epoxy obtained by nuclear hydrogenation of an aromatic polyhydroxy compound, which is a raw material of an aromatic epoxy compound represented by diglycidyl ether of bisphenol A, and converting it to glycidyl ether. The compound, an alicyclic epoxy compound having at least one epoxy group bonded to the alicyclic ring in the molecule, an aliphatic epoxy compound typified by a glycidyl ether of an aliphatic polyhydroxy compound, and the like. In addition to cationically polymerizable compounds, typically epoxy compounds, active energy ray-curable adhesives usually generate polymerization species, especially cationic species or Lewis acids upon irradiation with active energy rays. A cationic photopolymerization initiator for initiating polymerization of the active compound is blended. Further, a thermal cationic polymerization initiator that initiates polymerization by heating, and various other additives such as a photosensitizer may be blended.

When bonding protective films on both sides of the polarizer, the composition of the adhesive applied to each protective film may be the same or different, but from the viewpoint of productivity, moderate adhesive strength Therefore, it is preferable to use an adhesive having the same composition on both sides. That is, the composition of the adhesive layer 1 and the adhesive layer 2 is preferably the same in the polarizing plate of the present invention.

<Adhesive layer>
It is preferable that the polarizing plate of this invention has an adhesive layer for adhere | attaching with another member.

For forming the pressure-sensitive adhesive layer, an appropriate pressure-sensitive adhesive can be used, and the type thereof is not particularly limited. Adhesives include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, Examples thereof include cellulose-based pressure-sensitive adhesives.

Among these pressure-sensitive adhesives, those having excellent optical transparency, suitable wettability, cohesiveness, and adhesive pressure characteristics, and excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used as one exhibiting such characteristics. In particular, those formed of an adhesive containing an acrylic polymer and a crosslinking agent can be suitably used.

The acrylic adhesive is based on an acrylic polymer having a monomer unit of (meth) acrylic acid alkyl ester as a main skeleton. The (meth) acrylic acid alkyl ester refers to an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester, and (meth) in the present invention has the same meaning. Examples of the (meth) acrylic acid alkyl ester constituting the main skeleton of the acrylic polymer include linear or branched alkyl groups having 1 to 20 carbon atoms. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) acrylic Illustrative examples include isononyl acid, isomyristyl (meth) acrylate, and lauryl (meth) acrylate. These can be used alone or in combination. These alkyl groups preferably have an average carbon number of 3 to 9.

Among the acrylic polymers, it is preferable to use an acrylic polymer having a monomer unit of (meth) acrylic acid alkyl ester having high hydrophobicity as a main skeleton from the viewpoint of controlling the equilibrium moisture content to be low. In general, (meth) acrylic acid alkyl ester is a linear or branched alkyl group carbon in terms of optical transparency, moderate wettability and cohesion, adhesion, weather resistance and heat resistance. Those of formula 3 to 9, preferably 4 to 8, are preferably used practically. Among these alkyl groups, the larger the carbon number of the alkyl group, the higher the hydrophobicity, which is preferable for reducing the equilibrium moisture content. Examples of the alkyl (meth) acrylate include butyl (meth) acrylate and isooctyl (meth) acrylate. Among these, isooctyl (meth) acrylate having high hydrophobicity is preferable.

In the acrylic polymer, one or more kinds of copolymerization monomers can be introduced by copolymerization for the purpose of improving adhesiveness and heat resistance. Specific examples of such copolymerization monomers include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) acrylic acid 6 Hydroxyl-containing monomers such as hydroxyhexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate Carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; acid anhydrides such as maleic anhydride and itaconic anhydride Substance-based materials -Caprolactone adduct of acrylic acid; styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyl Examples thereof include sulfonic acid group-containing monomers such as oxynaphthalenesulfonic acid; and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate.

Also, (N-substituted) amides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc. Monomers; alkylaminoalkyl monomers (meth) acrylates such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and tert-butylaminoethyl (meth) acrylate; (meth) acrylic (Meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl acid and ethoxyethyl (meth) acrylate; N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- ( Meta) Acry Succinimide monomers such as yl-8-oxyoctamethylene succinimide and N-acryloylmorpholine; maleimide monomers such as N-cyclohexylmaleimide and N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide; N-methylitaconimide, Itaconimide monomers such as N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexylitaconimide, N-cyclohexyl itaconimide, N-lauryl itaconimide, etc. Take an example.

Further modifying monomers include vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, N- Vinyl monomers such as vinylcarboxylic amides, styrene, α-methylstyrene, N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; (Meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid meso Glycol acrylic ester monomers such as xypolypropylene glycol; acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate may also be used. it can.

The ratio of the copolymerization monomer in the acrylic polymer is not particularly limited, but is preferably about 0 to 30%, more preferably about 0.1 to 15% in the mass ratio of all the constituent monomers.

Among these copolymerized monomers, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and an acid anhydride group-containing monomer are preferably used from the viewpoints of adhesion to a liquid crystal cell and durability for optical film applications. These monomers serve as reaction points with the crosslinking agent. Hydroxyl group-containing monomers, carboxyl group-containing monomers, acid anhydride monomers, and the like are preferably used for improving the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer because they are highly reactive with intermolecular crosslinking agents. For example, the hydroxyl group-containing monomer is preferably 4-hydroxybutyl (meth) acrylate, more preferably 6-hydroxyhexyl (meth) acrylate, rather than 2-hydroxyethyl (meth) acrylate. It is preferable to use a hydroxyalkyl group having a large alkyl group. When a hydroxyl group-containing monomer is used as the copolymerization monomer, the proportion is preferably 0.01 to 5%, more preferably 0.01 to 3%, in the mass ratio of all the constituent monomers. Further, when a carboxyl group-containing monomer is used as a copolymerization monomer, the ratio is preferably 0.01 to 10%, more preferably 0.01 to 7%, in the mass ratio of all constituent monomers.

The average molecular weight of the acrylic polymer is not particularly limited, but the weight average molecular weight is preferably about 100,000 to 2.5 million. The acrylic polymer can be produced by various known methods. For example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method, or a suspension polymerization method can be appropriately selected. As the radical polymerization initiator, various known azo and peroxide initiators can be used. The reaction temperature is usually about 50 to 80 ° C., and the reaction time is 1 to 8 hours. Among the above production methods, the solution polymerization method is preferable, and ethyl acetate, toluene and the like are generally used as the solvent for the acrylic polymer. The solution concentration is usually about 20 to 80% by mass.

The pressure-sensitive adhesive is preferably a pressure-sensitive adhesive composition containing a crosslinking agent. Examples of the polyfunctional compound that can be blended in the pressure-sensitive adhesive include organic crosslinking agents and polyfunctional metal chelates. Examples of the organic crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, an imine crosslinking agent, and a peroxide crosslinking agent. These crosslinking agents can be used alone or in combination of two or more. As the organic crosslinking agent, an isocyanate crosslinking agent is preferable. Moreover, an isocyanate type crosslinking agent is used suitably in combination with a peroxide type crosslinking agent. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. can give. Examples of the atom in the organic compound that is covalently or coordinately bonded include an oxygen atom, and the organic compound includes an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, a ketone compound, and the like.

The blending ratio of the base polymer such as the acrylic polymer and the crosslinking agent is not particularly limited, but usually about 0.001 to 20 parts by mass of the crosslinking agent (solid content) is preferable with respect to 100 parts by mass of the base polymer (solid content). Furthermore, about 0.01 to 15 parts by mass is preferable. As said crosslinking agent, an isocyanate type crosslinking agent and a peroxide type crosslinking agent are preferable. The peroxide crosslinking agent is preferably about 0.01 to 3 parts by weight, preferably about 0.02 to 2.5 parts by weight, and more preferably 0.05 to 100 parts by weight of the base polymer (solid content). About 2.0 parts by mass is preferable. The isocyanate-based crosslinking agent is preferably about 0.001 to 2 parts by mass, and more preferably about 0.01 to 1.5 parts by mass with respect to 100 parts by mass of the base polymer (solid content). Moreover, an isocyanate type crosslinking agent and a peroxide type crosslinking agent can be used in the said range, and can be preferably used in combination of these.

Furthermore, the pressure-sensitive adhesive includes a silane coupling agent, a tackifier, a plasticizer, glass fiber, glass beads, an antioxidant, an ultraviolet absorber, transparent fine particles, and the like, if necessary, and does not depart from the purpose of the present invention. Various additives can be appropriately used within a range.

As the additive, a silane coupling agent is suitable, and the silane coupling agent (solid content) is preferably about 0.001 to 10 parts by mass with respect to 100 parts by mass of the base polymer (solid content). It is preferable to add about 005 to 5 parts by mass. As the silane coupling agent, those conventionally known can be used without particular limitation. For example, epoxy groups such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane Containing silane coupling agent, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine Amino group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, (meth) acrylic group-containing silane coupling agents such as 3-methacryloxypropyltriethoxysilane, and isocyanates such as 3-isocyanatopropyltriethoxysilane Base It can be exemplified a silane coupling agent.

Attaching the pressure-sensitive adhesive layer to the polarizing plate can be performed by an appropriate method. For example, a pressure-sensitive adhesive solution of about 10 to 40% by mass in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. An adhesive layer is formed on the separator in accordance with the above-mentioned method in which it is directly attached on the polarizing plate or the optical member by an appropriate development method such as a casting method or a coating method, or transferred to the polarizing plate. The method of wearing is mentioned.

<Functionalization of polarizing plate>
The polarizing plate of the present invention is a function that is combined with an optical film having functional layers such as an antireflection film, a brightness enhancement film, a hard coat layer, a forward scattering layer, and an antiglare (antiglare) layer for improving the visibility of the display. It is also preferably used as a polarizing plate. The antireflection film, brightness enhancement film, other functional optical film, hard coat layer, forward scattering layer, and antiglare layer for functionalization are described in JP-A-2007-86748, [0257] to [0276]. Thus, a functionalized polarizing plate can be created based on these descriptions.

[Production method of polarizing plate]
There is no restriction | limiting in particular as a method of manufacturing the polarizing plate of this invention, A well-known method can be used. Among them, the polarizing plate of the present invention can be easily manufactured with high productivity by the manufacturing method of the polarizing plate of the present invention described below.
The method for producing a polarizing plate of the present invention includes a step of bonding a first protective film having an in-plane retardation of 3000 nm or more to one surface of a polarizer having polarizing performance via an adhesive layer 1; A step of bonding a second protective film to the other surface of the polarizer through an adhesive layer 2 controlled to a film thickness different from that of the adhesive layer 1, and a step of curing and shrinking the adhesive layer 1 and the adhesive layer 2 It is preferable to include. Thus, by controlling the film thickness of the adhesive layer 2 to a film thickness different from that of the adhesive layer 1, the above formula (2) is satisfied even when the compositions of the adhesive layer 1 and the adhesive layer 2 are the same. Further, the curing shrinkage force of the adhesive layer 1 and the adhesive layer 2 can be controlled, which is preferable from the viewpoint of productivity.

(Bonding process of polarizer and protective film)
The method for producing a polarizing plate of the present invention includes a step of bonding a first protective film having an in-plane retardation of 3000 nm or more to one surface of a polarizer having polarizing performance via an adhesive layer 1; It includes a step of bonding a second protective film to the other surface of the polarizer via an adhesive layer 2 controlled to have a film thickness different from that of the adhesive layer 1.

The first protective film is bonded to one surface of the polarizer via the adhesive layer 1 and the adhesive layer 2 is controlled to a thickness different from that of the adhesive layer 1 on the other surface of the polarizer. The process of bonding the second protective film may be performed at the same time or sequentially. Among them, the step of bonding the first protective film to one surface of the polarizer via the adhesive layer 1, and the adhesive layer 2 controlled to a film thickness different from the adhesive layer 1 on the other surface of the polarizer. It is preferable to perform the process of bonding a 2nd protective film simultaneously through it, and it is more preferable to perform the process of bonding both using a roll-to-roll system simultaneously.
As a method for simultaneously performing both the bonding steps using a roll-to-roll method, for example, an apparatus and a method described in JP2012-203108A can be used, and a method described in JP2012-203108A can be used. The contents are incorporated into the present invention.
The manufacturing apparatus described in Japanese Patent Application Laid-Open No. 2012-203108, while continuously transporting a polarizer, a first protective film is bonded to one surface, and a second protective film is formed to the other surface. Are laminated to produce a polarizing plate, which is wound around a winding roll. Typically, a protective film is bonded to both sides of the polarizer.

The method of bonding the first protective film and the second protective film to the polarizer is not particularly limited, but the following bonding method is preferable.
The angle formed by the maximum direction of the elastic modulus in the plane of the first protective film and the absorption axis direction of the polarizer (generally the same as the stretching direction) is 90 ° at the end and the center in the width direction of the first protective film. It is preferably within ± 25 °. The angle formed between the maximum in-plane elastic modulus direction of the first protective film and the absorption axis direction of the polarizer is more preferably 90 ° ± 20 °, and particularly preferably 90 ° ± 5 °. .
On the other hand, it is preferable to bond the polarizer so that the transmission axis of the polarizer and the slow axis of the second protective film are substantially parallel. Here, being substantially parallel means that the deviation between the direction of the main refractive index nx of the second protective film and the direction of the transmission axis of the polarizing plate is within 5 °, preferably 1 Within 0 °, more preferably within 0.5 °. If the deviation is within 1 °, the polarization degree performance under the polarizing plate crossed Nicol is unlikely to deteriorate, and light leakage is less likely to occur.

In the present invention, as a method of providing the adhesive layer 1 and the adhesive layer 2, a conventionally known coating method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, or the like can be used. As for the coating method, there is a description example in “Coating method” published by Yoji Harasaki in 1979.
The first protective film and the second protective film may be subjected to surface treatment such as saponification treatment, corona treatment, and plasma treatment in advance.

(Step of curing and shrinking the adhesive layer)
The method for producing a polarizing plate of the present invention includes a step of curing and shrinking the adhesive layer 1 and the adhesive layer 2. There is no restriction | limiting in particular as a process of carrying out hardening shrinkage of the contact bonding layer 1 and the contact bonding layer 2, A well-known method can be used.
The manufacturing method of the polarizing plate of the present invention includes an adhesive in which the adhesive layer 1 and the adhesive layer 2 are cured by active energy rays, and the step of curing and shrinking the adhesive layer 1 and the adhesive layer 2 irradiates the active energy rays to bond. It is preferable to be a step of simultaneously curing the layer 1 and the adhesive layer 2.

The active energy ray in the step of curing and shrinking the adhesive layer is not particularly limited, and a known active energy ray can be used. Among these, in the present invention, the active energy ray is preferably ultraviolet rays.

When the active energy rays are ultraviolet rays, the adhesive layer 1 and the adhesive layer 2 contain an adhesive that is cured by ultraviolet rays, and one of the first protective film and the second protective film contains an ultraviolet absorber. Is preferably irradiated with ultraviolet rays from the side of the protective film not containing the ultraviolet absorber.
Among them, in the method for producing a polarizing plate of the present invention, the first protective film contains an ultraviolet absorber, and the step of curing and shrinking the adhesive layer 1 and the adhesive layer 2 irradiates ultraviolet rays from the second protective film side. It is preferable to be a step of simultaneously curing the adhesive layer 1 and the adhesive layer 2. FIG. 2 shows a schematic diagram of such an embodiment. In FIG. 2, the first protective film (reference numeral 1 in the figure) contains an ultraviolet absorber, and ultraviolet rays (reference numeral UV in the figure) are irradiated from the second protective film (reference numeral 3 in the figure) side. (Reference numeral 11 in the figure) and the adhesive layer 2 (reference numeral 12 in the figure) are simultaneously cured. With such a configuration, even when the first protective film contains an ultraviolet absorber, curling that occurs when a polarizing plate is produced by laminating a polarizer and two protective films using a curable adhesive. The polarizing plate of the present invention can be produced with good productivity while suppressing the above. In particular, when the first protective film is a polyester film containing a polyester resin as a main component, it is preferable to add an ultraviolet absorber. Therefore, the adhesive layer 1 and the adhesive layer 2 are cured and shrunk in this manner. Is preferred.

[Image display device]
The image display device of the present invention includes the polarizing plate of the present invention.
Examples of the image display device include a liquid crystal display (LCD), a plasma display (PDP), an electroluminescence display (OELD or IELD), a field emission display (FED), a touch panel, and electronic paper. These image display devices preferably include the polarizing plate of the present invention on the display screen side of the image display panel.

<Method of bonding polarizing plate to image display device>
As a method for bonding the polarizing plate of the present invention to an image display device such as a liquid crystal display device, a roll-to-panel manufacturing method can be used, which is preferable in terms of improving productivity and yield. The roll-to-panel manufacturing method is described in JP-A-2011-48381, JP-A-2009-175653, JP-A-4628488, JP-B-4729647, WO2012 / 014602, WO2012 / 014571, and the like. It is not limited.

<Liquid crystal display device>
The liquid crystal display device preferably includes the polarizing plate of the present invention and a liquid crystal display element. Here, the liquid crystal display element is typically a liquid crystal panel having a liquid crystal cell in which liquid crystal is sealed between upper and lower substrates and displaying an image by changing the alignment state of the liquid crystal by applying a voltage. The polarizing plate of the present invention can be applied to various known displays such as a display panel, a CRT display, and an organic EL display. Thus, when the polarizing plate of this invention which has a 1st protective film with high retardation is applied to a liquid crystal display element, the curvature of a liquid crystal display element can be prevented.

Here, the rainbow-like color spots are caused by the retardation of the first protective film having a high retardation and the emission spectrum of the backlight light source. Conventionally, a fluorescent tube such as a cold cathode tube or a hot cathode tube is used as a backlight source of a liquid crystal display device. The spectral distribution of a fluorescent lamp such as a cold cathode tube or a hot cathode tube shows an emission spectrum having a plurality of peaks, and these discontinuous emission spectra are combined to obtain a white light source. When light passes through a film having a high retardation, the transmitted light intensity varies depending on the wavelength. For this reason, when the backlight light source has a discontinuous emission spectrum, only a specific wavelength is strongly transmitted, and a rainbow-like color spot is generated.

When the image display device of the present invention is a liquid crystal display device, it is preferable to include a backlight light source and a liquid crystal cell disposed between two polarizing plates as constituent members. Moreover, you may have suitably other structures other than these, for example, a color filter, a lens film, a diffusion sheet, an antireflection film etc. suitably.

The configuration of the backlight may be an edge light method using a light guide plate, a reflection plate, or the like, or a direct type, but in the present invention, white is used as the backlight light source of the liquid crystal display device. It is necessary to use a light emitting diode (white LED). In the present invention, the white LED is an element that emits white by combining a phosphor with a phosphor system, that is, a light emitting diode that emits blue light or ultraviolet light using a compound semiconductor. Examples of the phosphor include yttrium / aluminum / garnet yellow phosphor and terbium / aluminum / garnet yellow phosphor. Above all, white light-emitting diodes, which are composed of light-emitting elements that combine blue light-emitting diodes using compound semiconductors with yttrium, aluminum, and garnet-based yellow phosphors, have a continuous and broad emission spectrum and also have high luminous efficiency. Since it is excellent, it is suitable as a backlight light source of the image display device of the present invention. Here, the continuous emission spectrum means that there is no wavelength at which the light intensity becomes zero at least in the visible light region. Further, since the white LED with low power consumption can be widely used according to the present invention, an effect of energy saving can be achieved.
The mechanism by which the occurrence of rainbow-like color spots is suppressed by the above embodiment is described in International Publication No. WO2011 / 162198, and the contents of this publication are incorporated in the present invention.

When the image display device of the present invention is a liquid crystal display device, the arrangement of the polarizing plate of the present invention is not particularly limited. The polarizing plate of the present invention is preferably used as a polarizing plate for the viewing side in a liquid crystal display device.
The arrangement of the first protective film having a high in-plane retardation is not particularly limited, but is arranged on the incident light side (light source side), the polarizing plate, the liquid crystal cell, and the outgoing light side (viewing side). In the case of a liquid crystal display device provided with a polarizing plate, the polarizer protective film on the incident light side of the polarizing plate arranged on the incident light side, or the polarizer on the outgoing light side of the polarizing plate arranged on the outgoing light side The protective film is preferably the first protective film having a high in-plane retardation. A particularly preferred embodiment is an embodiment in which the polarizer protective film on the exit light side of the polarizing plate disposed on the exit light side is the first protective film having a high in-plane retardation. When the first protective film having a high in-plane retardation is disposed at a position other than the above, the polarization characteristics of the liquid crystal cell may be changed. Since the first protective film having a high retardation in the in-plane direction is preferably used in a place where the polarization characteristic is not required, it is preferably used as a protective film for the polarizing plate at such a specific position.

A schematic diagram of a preferred example of a liquid crystal display device is shown in FIG.
The liquid crystal display device 30 shown in FIG. 4 has the polarizing plates 20 and 21 of the present invention as the viewing side polarizing plate, and the backlight side polarizing plate 23 on the liquid crystal cell 22 side. The liquid crystal display device 30 has a backlight 26. It does not specifically limit as the backlight side polarizing plate 23, The same polarizing plate as the visual recognition side polarizing plate 21 may be sufficient, and a well-known polarizing plate may be sufficient.
The liquid crystal cell preferably has a liquid crystal layer and two glass substrates provided on both sides of the liquid crystal layer. The thickness of the glass substrate is preferably 0.5 mm or less, more preferably 0.4 mm or less, and particularly preferably 0.3 mm or less.
The liquid crystal cell of the liquid crystal display device is preferably IPS mode, VA mode, or FFS mode.

Hereinafter, the features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
<< Preparation of first protective film >>
<Synthesis of raw material polyester>
(Raw material polyester 1)
As shown below, terephthalic acid and ethylene glycol are directly reacted to distill off water, esterify, and then, using a direct esterification method in which polycondensation is performed under reduced pressure, raw polyester 1 ( Sb catalyst system PET) was obtained.

(1) Esterification reaction In a first esterification reactor, 4.7 tons of high-purity terephthalic acid and 1.8 tons of ethylene glycol are mixed over 90 minutes to form a slurry, and continuously at a flow rate of 3800 kg / h. It supplied to the 1st esterification reaction tank. Further, an ethylene glycol solution of antimony trioxide was continuously supplied, and the reaction was carried out at a reaction vessel temperature of 250 ° C. with stirring and an average residence time of about 4.3 hours. At this time, antimony trioxide was continuously added so that the amount of Sb added was 150 ppm in terms of element.

The reaction product was transferred to a second esterification reaction vessel, and reacted with stirring at a temperature in the reaction vessel of 250 ° C. and an average residence time of 1.2 hours. To the second esterification reaction tank, an ethylene glycol solution of magnesium acetate and an ethylene glycol solution of trimethyl phosphate are continuously supplied so that the added amount of Mg and the added amount of P are 65 ppm and 35 ppm in terms of element, respectively. did.

(2) the polycondensation reaction above-obtained esterification reaction product supplied to the first polycondensation reaction vessel continuously stirring, the reaction temperature 270 ° C., the reaction vessel pressure 20 torr (2.67 × 10 ^{- 3} MPa) and polycondensation with an average residence time of about 1.8 hours.

Further, it was transferred to the second double condensation reaction tank, and while stirring in this reaction tank, the reaction tank temperature was 276 ° C., the reaction tank pressure was 5 torr (6.67 × 10 ⁻⁴ MPa), and the residence time was about 1.2 hours. The reaction (polycondensation) was performed under the conditions.

Subsequently, it was further transferred to the third triple condensation reaction tank, in which the temperature in the reaction tank was 278 ° C., the pressure in the reaction tank was 1.5 torr (2.0 × 10 ⁻⁴ MPa), and the residence time was 1.5 hours. The reaction product (polyethylene terephthalate (PET)) was obtained by reaction (polycondensation) under the following conditions.

Next, the obtained reaction product was discharged into cold water in a strand shape and immediately cut to prepare polyester pellets (cross section: major axis: about 4 mm, minor axis: about 2 mm, length: about 3 mm).

The obtained polymer had an intrinsic viscosity IV = 0.63. This polymer was designated as raw material polyester 1.

In IV, the raw material polyester film 1 is dissolved in a 1,1,2,2-tetrachloroethane / phenol (= 2/3 [mass ratio]) mixed solvent, and from the solution viscosity at 25 ° C. in the mixed solvent. Asked.

(Raw material polyester 2)
10 parts by weight of a dried UV absorber (2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), raw material polyester 1 (IV = 0.63) 90 The raw material polyester 2 containing an ultraviolet absorber was obtained by mixing the mass parts and using a kneading extruder.

-Film forming process-
The raw material polyester 1 (90 parts by mass) and the raw material polyester 2 containing ultraviolet absorbers (10 parts by mass) are dried to a water content of 20 ppm or less and then put into the hopper 1 of a single-screw kneading extruder 1 having a diameter of 50 mm. And was melted to 300 ° C. by the extruder 1. Extrusion was performed from a die through a gear pump and a filter (pore diameter: 20 μm) under the following extrusion conditions.
The molten resin was extruded from the die under the conditions that the pressure fluctuation was 1% and the temperature distribution of the molten resin was 2%. Specifically, the back pressure was increased by 1% with respect to the average pressure in the barrel of the extruder, and the piping temperature of the extruder was heated at a temperature 2% higher than the average temperature in the barrel of the extruder.
The molten resin extruded from the die was extruded onto a cooling cast drum set at a temperature of 25 ° C., and was brought into close contact with the cooling cast drum using an electrostatic application method. It peeled using the peeling roll arrange | positioned facing the cooling cast drum, and the unstretched polyester film 1 was obtained.

The obtained unstretched polyester film 1 is guided to a tenter (lateral stretching machine), and the following method and conditions are used in the TD direction (film width direction, lateral direction) while gripping the end of the film with a clip. The film was stretched transversely under conditions to produce a PET film 1 (hereinafter abbreviated as PET1) having a thickness of 80 μm and a width of 1330 mm.
"conditions"
-Transverse stretching temperature: 90 ° C
・ Horizontal stretch ratio: 4.3 times

(Heat fixing part)
Next, a heat setting treatment was performed while controlling the film surface temperature of the polyester film within the following range.
<Condition>
・ Heat setting temperature: 180 ℃
・ Heat setting time: 15 seconds

(Heat relaxation part)
The polyester film after heat setting was heated to the following temperature to relax the film.
-Thermal relaxation temperature: 170 ° C
-Thermal relaxation rate: TD direction (film width direction, lateral direction) 2%

(Cooling section)
Next, the polyester film after heat relaxation was cooled at a cooling temperature of 50 ° C.

<< Creation of second protective film >>
<Manufacture of COP1>
“Zeonor 1420 R” {manufactured by Nippon Zeon Co., Ltd., thickness 100 μm} was longitudinally stretched at a supply temperature of 140 ° C. and a film film surface temperature of 130 ° C. at a stretching ratio of 30% in a longitudinal uniaxial stretching machine. Then, in a tenter stretching machine, the film is stretched horizontally at an air supply temperature of 140 ° C. and a film film surface temperature of 130 ° C. at a stretching ratio of 40%, and both ends are cut off in front of the winding portion to a width of 1330 mm and wound as a roll film having a length of 4000 m I took it. A biaxially stretched thermoplastic resin film (hereinafter abbreviated as COP1) was obtained (film thickness 52 μm, Re = 50 nm, Rth = 120 nm).

<Polarizing plate processing>
(Production of polarizer)
According to Example 1 of Japanese Patent Laid-Open No. 2001-141926, iodine was adsorbed to a stretched polyvinyl alcohol film to prepare a polarizer having a thickness of 24 μm.

(Preparation of adhesive 1)
A polarizing plate adhesive was prepared by blending 100 parts by mass of 2-hydroxyethyl acrylate, 10 parts by mass of tolylene diisocyanate, and 3 parts by mass of a photopolymerization initiator (Irgacure 907, manufactured by BASF). This was designated as Adhesive 1.

(Preparation of polarizing plate)
The surface of the PET1 and COP1 was subjected to corona treatment. Next, using a micro gravure coater (gravure roll: # 300, rotational speed 140% / line speed), the thickness of the adhesive layer 1 between the first protective film PET1 and the polarizer is set to 3.0 μm, Adhesive 1 was applied on each film so that the film thickness of the adhesive layer 2 between the second protective film COP1 and the polarizer was 1.5 μm to obtain a protective film with an adhesive. Then, the said protective film with an adhesive agent was bonded together on both surfaces of the said polarizer by the roll to roll with the roll machine. The adhesive was cured by irradiating ultraviolet rays from the bonded COP 1 side, and the layers were bonded. The line speed was 20 m / min, and the cumulative amount of ultraviolet light was 300 mJ / cm ² . In this way, a polarizing plate in which both surfaces having a film length of 500 m were protected by the first and second optical films was obtained. This polarizing plate was used as the polarizing plate of Example 1.

[Production of Image Display Device 1]
Peel off the two polarizing plates of a commercially available VA type liquid crystal television (Skyworth 39E61HR), the polarizing plate of Example 1 on the front side (viewing side) and the rear side (non-viewing side), the second protective film One sheet was attached to each of the front side and the rear side via an adhesive so as to be on the liquid crystal cell side. The crossed Nicols were arranged so that the absorption axis of the front-side polarizing plate was in the longitudinal direction (left-right direction) and the transmission axis of the rear-side polarizing plate was in the longitudinal direction (left-right direction). The thickness of the glass used for the liquid crystal cell was 0.5 mm. This display characteristic was good.
The liquid crystal display device thus obtained was designated as the image display device 1 of Example 1.

[Example 2]
The polarizing plate of Example 2 is the same as Example 1 except that the film thickness of the adhesive layer 2 between the second protective film and the polarizer is changed from 1.5 μm to 0.6 μm in Example 1. And the image display apparatus 1 was manufactured.

[Comparative Example 1]
In Example 1, the polarizing plate of Comparative Example 1 was prepared in the same manner as in Example 1 except that the film thickness of the adhesive layer 2 between the second protective film and the polarizer was changed from 1.5 μm to 3.0 μm. And the image display apparatus 1 was manufactured.

[Example 3]
In Example 1, the thickness of the adhesive layer 1 between the first protective film and the polarizer was changed from 3.0 μm to 1.0 μm, and the adhesion between the second protective film and the polarizer A polarizing plate of Example 3 and the image display device 1 were manufactured in the same manner as Example 1 except that the film thickness of the layer 2 was changed from 1.5 μm to 0.2 μm.

[Comparative Example 2]
A PET film 2 (hereinafter abbreviated as PET2) was produced in the same manner as in Example 1 except that the PET1 of Example 1 was stretched 3 times in the longitudinal direction. The PET2 as a first protective film,
The same as in Example 1 except that COP1 was used as the second protective film and the thickness of the adhesive layer 2 between the second protective film and the polarizer was changed from 1.5 μm to 3.0 μm. The polarizing plate of Comparative Example 2 and the image display device 1 were manufactured.

[Example 4]
In Example 1, instead of PET1, the following PET film 3 (hereinafter abbreviated as PET3) is used as the first protective film, and the film thickness of the adhesive layer 2 between the first protective film and the polarizer is used. Is changed from 3.0 μm to 5.0 μm, and the film thickness of the adhesive layer 2 between the second protective film and the polarizer is changed from 1.5 μm to 0.6 μm. Thus, the polarizing plate of Example 4 and the

image display devices

1 and 2 were produced.
The manufacturing method of PET film 3 is shown below.

-Formation of easy-bonding layer-
(1) Formation of hard coat layer side easy-adhesion layer The following compounds were mixed in the following ratio to prepare a coating liquid H1 for the hard coat layer-side easy adhesive layer. On PET1 obtained in Example 1, the coating liquid H1 for the hard coat layer-side easy-adhesion layer was applied in a film thickness of 0.09 μm.

・ Coating liquid H1 for hard coat layer side easy adhesion layer
Polyester resin: (IC) 60 parts by mass Acrylic resin: (II) 25 parts by mass Melamine compound: (VIB) 10 parts by mass Particles: (VII) 5 parts by mass Details of the compounds used are shown below.
・ Polyester resin: (IC)
Polyester resin sulfonic acid aqueous dispersion monomer composition copolymerized with monomers of the following composition: (acid component) terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid // (diol component) ethylene glycol / 1,4- Butanediol / diethylene glycol = 56/40/4 // 70/20/10 (mol%)

・ Acrylic resin: (II)
Aqueous dispersion of acrylic resin polymerized with monomers having the following composition: Emulsion polymer of ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylol acrylamide / acrylic acid = 65/21/10/2/2 (mass%) Emulsifier: Anionic surfactant)
-Urethane resin: (IIIB)
400 parts by weight of polycarbonate polyol composed of 1,6-hexanediol and diethyl carbonate having a number average molecular weight of 2000, 10.4 parts by weight of neopentyl glycol, 58.4 parts by weight of isophorone diisocyanate, 74.3 parts by weight of dimethylol butanoic acid. An aqueous dispersion of urethane resin obtained by neutralizing a prepolymer consisting of parts by mass with triethylamine and extending the chain with isophoronediamine.
Melamine compound: (VIB) hexamethoxymethylmelamine Particles: (VII) Silica sol having an average particle size of 65 nm

<Formation by applying a hard coat layer>
Thereafter, a mixed coating liquid (acryl-1) having the following composition is applied to the surface of the PET 1 obtained in Example 1 on which the coating liquid H1 for the hard coat layer-side easy-adhesion layer is applied so that the dry film thickness becomes 5 μm. It was applied, dried, and cured by irradiating with ultraviolet rays to form a hard coat layer.
Dipentaerythritol hexaacrylate 85 parts by mass 2-hydroxy-3-phenoxypropyl acrylate 15 parts by mass Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) 5 parts by mass Methyl ethyl ketone 200 parts by mass

[Example 5]
A PET film 4 (hereinafter abbreviated as PET4) having a thickness changed to 60 μm was produced in the same manner as the PET film 1 of Example 1. Example 1 except that PET4 was used instead of PET1 as the first protective film, and the film thickness of the adhesive layer 2 between the second protective film and the polarizer was changed from 1.5 μm to 1.8 μm. Similarly, the polarizing plate of Example 5 and the image display apparatus 1 were manufactured.

[Example 6]
A PET film 5 (hereinafter abbreviated as “PET5”) having a thickness changed to 40 μm was produced in the same manner as the PET film 1 of Example 1. Example 1 except that PET5 was used instead of PET1 as the first protective film, and the film thickness of the adhesive layer 2 between the second protective film and the polarizer was changed from 1.5 μm to 3.8 μm. Similarly, the polarizing plate of Example 6 and the image display apparatus 1 were manufactured.

[Example 7]
In Example 1, instead of PET1, the following PET film 6 (hereinafter abbreviated as PET6) was used as the first protective film, and COP2 produced in Comparative Example 2 was used as the second protective film instead of COP1. And the polarizing plate of Example 7 except that the film thickness of the adhesive layer 2 between the second protective film and the polarizer was changed from 1.5 μm to 2.0 μm,

Image display devices

1 and 2 were manufactured.

<Manufacture of PET film 6>
-Film forming process-
The raw material polyester 1 (90 parts by mass) and the raw material polyester 2 containing ultraviolet absorbers (10 parts by mass) are dried to a moisture content of 20 ppm or less, and then charged into the hopper 1 of a uniaxial kneading extruder 1 having a diameter of 50 mm. Then, it was melted at 300 ° C. by the extruder 1 (intermediate layer II layer).
Moreover, after drying PET1 to a water content of 20 ppm or less, it was put into a hopper 2 of a single screw kneading extruder 2 having a diameter of 30 mm and melted at 300 ° C. by the extruder 2 (outer layer I layer, outer layer III layer).
These two kinds of polymer melts are respectively passed through a gear pump and a filter (pore diameter 20 μm), and then the polymer extruded from the extruder 1 is extruded into an intermediate layer (II layer) in a two-type three-layer confluence block. The polymer extruded from the machine 2 was laminated so as to be outer layers (I layer and III layer), and extruded from a die into a sheet.
The molten resin was extruded from the die under the conditions that the pressure fluctuation was 1% and the temperature distribution of the molten resin was 2%. Specifically, the back pressure was increased by 1% with respect to the average pressure in the barrel of the extruder, and the piping temperature of the extruder was heated at a temperature 2% higher than the average temperature in the barrel of the extruder.
The molten resin extruded from the die was extruded onto a cooling cast drum set at a temperature of 25 ° C., and was brought into close contact with the cooling cast drum using an electrostatic application method. It peeled off using the peeling roll arrange | positioned facing the cooling cast drum, and the unstretched polyester film 2 was obtained. At this time, the discharge amount of each extruder was adjusted so that the ratio of the thicknesses of the I layer, the II layer, and the III layer was 10:80:10.

The obtained unstretched polyester film 2 was horizontally stretched under the same conditions as in Example 1 to produce a PET film 6 having a thickness of 80 μm.

[Example 8]
In Example 1, instead of COP1 as the second protective film, an acrylic film 1 (hereinafter abbreviated as PMMA1) shown below is used, and the adhesive layer 2 between the second protective film and the polarizer is used. A polarizing plate of Example 8 was obtained in the same manner as Example 1 except that the film thickness was changed from 1.5 μm to 0.6 μm. An image display device 2 shown below was produced using this polarizing plate.

(Meth) acrylic resin having a lactone ring structure in which R ¹ is a hydrogen atom and R ² and R ³ are methyl groups in the above general formula {mass ratio of copolymerization monomer = methyl methacrylate / 2- (hydroxymethyl) acrylic Methyl acid = 8/2, lactone cyclization rate about 100%, lactone ring structure content 19.4%, mass average molecular weight 133000, melt flow rate 6.5 g / 10 min (240 ° C., 10 kgf), Tg 131 ° C.} A mixture of 90 parts by mass and 10 parts by mass of acrylonitrile-styrene (AS) resin {Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.}; Pellets with a Tg of 127 ° C. are fed to a twin screw extruder and melted into a sheet at about 280 ° C. Extrusion was performed to obtain a (meth) acrylic resin sheet having a lactone ring structure. This unstretched sheet was stretched vertically and horizontally under a temperature condition of 160 ° C. to obtain PMMA 1 (thickness: 41 μm, in-plane retardation Re: 0.8 nm, thickness direction retardation Rth: 1.5 nm). .

[Production of image display device 2]
The two polarizing plates of the IPS mode liquid crystal cell (made by LGD 42LS5600) are peeled off, the polarizing plate of Example 1 is applied to the front side (viewing side) and the rear side (non-viewing side), and the second protective film is a liquid crystal. One sheet was attached to each of the front side and the rear side via an adhesive so as to be on the cell side. The crossed Nicols were arranged so that the absorption axis of the front-side polarizing plate was in the longitudinal direction (left-right direction) and the transmission axis of the rear-side polarizing plate was in the longitudinal direction (left-right direction). The thickness of the glass used for the liquid crystal cell was 0.5 mm. This display characteristic was good.
The liquid crystal display device thus obtained was designated as an image display device 2 of Example 8.

[Example 9]
In Example 1, instead of COP1 as the second protective film, the following cellulose acylate film 1 (hereinafter abbreviated as DAC1) was used after saponification under the following conditions, and the second protective film and The polarizing plate of Example 9 and the

image display devices

1 and 2 are manufactured in the same manner as in Example 1 except that the film thickness of the adhesive layer 2 between the polarizer and the polarizer is changed from 1.5 μm to 2.0 μm. did.

<Manufacture of DAC1>
(Preparation of cellulose acylate)
Cellulose acylate was synthesized by the method described in JP-A Nos. 10-45804 and 08-231761, and the degree of substitution was measured. Specifically, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. In addition, aging was performed at 40 ° C. after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.

(Preparation of core layer cellulose acylate dope)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution.
Composition of core layer cellulose acylate dope:
---------------------------------
Cellulose acetate (degree of substitution 2.45) 100 parts by weight Compound A 19 parts by weight Methylene chloride (first solvent) 365.5 parts by weight Methanol (second solvent) 54.6 parts by weight -------- --------------------------

The compound A represents a terephthalic acid / succinic acid / propylene glycol / ethylene glycol copolymer (copolymerization ratio [mol%] = 27.5 / 22.5 / 25/25).

(Preparation of outer layer cellulose acylate dope)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution. The amount of the solvent (methylene chloride and methanol) was appropriately adjusted so that the solid content concentration of the cellulose acylate solution was 19.7 (mass%).
Composition of outer layer cellulose acylate dope:
---------------------------------
Cellulose acetate (substitution degree 2.79) 100.0 parts by mass Compound A 11.0 parts by mass Silica fine particles R972 (manufactured by Nippon Aerosil) 0.15 parts by mass Methylene chloride 395.0 parts by mass Methanol 59.0 Mass part ---------------------------------
The outer layer cellulose acylate solution is formed into a skin A layer and a skin B layer each having a thickness of 2 μm after drying so that the film thickness after drying the core layer cellulose acylate solution is 56 μm, respectively. Casted. The obtained web (film) was peeled off from the band, sandwiched between clips, and a tenter was used at a stretching temperature of 140 ° C. and a stretching ratio of 1.08 when the amount of residual solvent relative to the total mass of the film was 20-5%. And stretched laterally.
Then, after removing the clip from the film and drying at 130 ° C. for 20 minutes, the film was further stretched again using a tenter at a stretching temperature of 180 ° C. and a stretching ratio of 1.2 times.
The residual solvent amount was determined according to the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is a mass of the web at an arbitrary time point, and N is a mass when the web of which M is measured is dried at 120 ° C. for 2 hours.
In this way, DAC1 was obtained. The film thickness was 58 μm. Re was 54 nm and Rth was 120 nm.

[Comparative Example 3]
In Example 5, the thickness of the adhesive layer 1 between the first protective film and the polarizer was changed from 3.0 μm to 4.0 μm, and the adhesion between the second protective film and the polarizer A polarizing plate of Comparative Example 3 and the

image display devices

1 and 2 were manufactured in the same manner as in Example 5 except that the film thickness of the layer 2 was changed from 1.8 μm to 0.8 μm.

[Protective film characteristics, adhesive layer, polarizer characteristics evaluation, polarizing plate evaluation]
Characteristic evaluation of the first and second protective films used in the polarizing plates of each Example and Comparative Example, characteristic evaluation of the

adhesive layers

1 and 2, characteristic evaluation of the polarizer, and polarization of each Example and Comparative Example Evaluation of the plate and evaluation of the

image display devices

1 and 2 of each example and comparative example were performed by the following methods.
The obtained results are shown in Table 1 below.

<Re, Rth, Nz of the first protective film>
Using two polarizing plates, the orientation axis direction of the first protective film was determined, and a 4 cm × 2 cm rectangle was cut out so that the orientation axis directions were orthogonal to each other, and used as a measurement sample. With respect to this sample, the biaxial refractive index (Nx, Ny) perpendicular to each other and the refractive index (Nz) in the thickness direction were determined by an Abbe refractometer (NAGO-4T manufactured by Atago Co., Ltd., measurement wavelength 589 nm). Furthermore, the thickness y ₁ (nm) of the first protective film was measured using an electric micrometer (Millitron 1245D, manufactured by Fine Reef Co., Ltd.), and the unit was converted to nm. Measured Nx, Ny, Nz, Re from the value of _{y 1,} Rth, Nz was calculated.

<Re, Rth of the second protective film>
The sample film was conditioned for 24 hours at 25 ° C and 60% relative humidity, and then the surface of the film was measured at 25 ° C and 60% relative humidity using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments). The phase difference at a wavelength of 590 nm is measured from the direction inclined in increments of 10 ° from + 50 ° to −50 ° from the normal to the film surface with the vertical direction and the slow axis as the rotation axis, and the in-plane retardation value (Re ) And the retardation value (Rth) in the film thickness direction.

<Thickness of polarizing plate, protective film, adhesive layer, polarizer>
The cross section of the manufactured polarizing plate was observed with SEM (scanning microscope), and the thicknesses of the polarizing plate, the first and second protective films, the adhesive layer, and the polarizer were measured.
<Protective film, adhesive layer, elastic modulus of polarizer>
Samples having a measurement direction length of 200 mm and a width of 10 mm were prepared for the elastic modulus in the MD direction and TD direction of the first and second protective films and in the MD direction of the polarizing plate. Using V10-C, the sample shape was measured with a width of 10 mm and a length between chucks of 100 mm.
The elastic modulus of the polarizer was obtained by the following formula (7) by measuring the elastic modulus Et and the total film thickness yt of the entire polarizing plate by the above method.

The elastic modulus of the adhesive layer was measured in the same manner as the protective film, after coating the adhesive 1 on the separator and irradiating ultraviolet rays to produce a test piece having the same size as the sample size.

In addition, the maximum direction of the elastic modulus in the surface of the first protective film was adjusted for 2 hours or more in an atmosphere of 25 ° C. and 60% relative humidity using a sound velocity measuring device “SST-2501, Nomura Corporation”. With respect to the wet film, the sound speed was measured by dividing the 360 degree direction into 32 parts in an atmosphere of 25 ° C. and a relative humidity of 60%, and the maximum speed direction was determined as the maximum direction of the in-plane elastic modulus. As a result, it was found that the maximum direction of the in-plane elastic modulus of the first protective film was the TD direction, which was perpendicular to the absorption axis of the polarizer.

<Curing shrinkage rate at the time of bonding of polarizing plates of

adhesive layers

1 and 2>
Cure shrinkage of the

adhesive layer

1 and 2 epsilon (%) is the density ρ1 (g / ^cm 3) of adhesive 1 before curing, dry density density of the adhesive 1 ρ2 (g / cm ³⁾ after curing It measured with the measuring machine (The Shimadzu make, Accupic 1340), and computed by following formula (8).
ε = (1-ρ1 / ρ2) × 100 (8)

<Film thickness of

adhesive layers

1 and 2>
The cross section of the manufactured polarizing plate was observed with SEM (scanning microscope), and the film thicknesses of the

adhesive layers

1 and 2 were measured.

<Curing shrinkage force at the time of bonding of polarizing plate of adhesive 1>
The curing shrinkage force S at the time of bonding the polarizing plate of the adhesive 1 was calculated by the following method based on the elastic modulus, curing shrinkage, and film thickness of the adhesive 1 obtained above.
Curing shrinkage force (N / m) = Curing shrinkage rate × Elastic modulus × Film thickness

<Curl evaluation>
A test piece having a size of (MD) 15 cm × (TD) 1.5 cm was cut out from the produced polarizing plate and placed in a temperature-humidity environment at 25 ° C. and a relative humidity of 60% for 4 hours or more. The curl amount in the MD direction, that is, the curl amount in the absorption axis direction of the polarizer) was measured. At this time, the amount of lifting when the first protective film side (outer side) is placed upward is defined as the plus direction. When the prepared sample is warped on the second protective film side (inner side), the amount of lifting cannot be measured even if the first protective film side (outer side) is placed upwards. The second protective film side (inner side) is placed upwards, the amount of lifting is measured, and a minus sign is given. In addition, when cutting out a test piece, it cut out from the center part of a polarizing plate.
The average lift of the four corners of the polarizing plate (the curl amount in the MD direction, that is, the curl amount in the absorption axis direction of the polarizer) is most preferably less than 3 mm. Next, 3 mm or more and less than 10 mm is preferable. 10 mm or more is not preferable, and this is C. Practically, it is necessary to be A evaluation or B evaluation, and it is preferable that it is A evaluation.
In addition, when the curl amount in the MD direction of the polarizing plate (absorption axis direction of the polarizer) becomes negative, bubbles are likely to be formed when being bonded to the liquid crystal cell, which is not preferable.

<Evaluation of polarizing plate defects>
Of the polarizing plates obtained with a width of 1330 mm in the examples and comparative examples, the central 1250 mm width portion excluding the 40 mm width portions at both ends as the effective width, and the surface over the length of 1000 mm in the conveying direction within the effective width, Bubbles were observed by visual observation. The case where bubbles were not observed was designated as “A”, and the case where bubbles were clearly observed was designated as “B”.
Practically, there is no problem even if it is B evaluation, but A evaluation is preferable.

<Rainbow-like unevenness evaluation of

image display devices

1 and 2>
The produced liquid crystal display devices (the

image display devices

1 and 2 described above) were visually evaluated by a plurality of observers for rainbow-like unevenness during white display.
-Evaluation index-
A: Iridescent unevenness was hardly observed.
B: Rainbow-like unevenness was weak, but was observed to the extent that it was visible.
C: Iridescent unevenness is clearly observed and is not acceptable.
Practically, it is necessary to be A evaluation or B evaluation, and it is preferable that it is A evaluation. In any case, the

image display devices

1 and 2 had the same evaluation.

<Evaluation results>
From Examples 1 and 2 in Table 1 above, the polarizing plate of the present invention occurs when a polarizing plate is produced by laminating a polarizer and two protective films using a curable adhesive (MD direction, ie, It was found that curling (in the absorption axis direction of the polarizer) can be suppressed, and rainbow-like unevenness is difficult to be visually recognized when incorporated in a liquid crystal display device.
On the other hand, it was found from Comparative Example 1 that when the lower limit value of the range of the formula (2) is below (the moment due to the curing shrinkage force ratio between the adhesive layers 1 and 2), the curling of the polarizing plate increases.
When the thickness of the adhesive layer was made thinner than in Example 3, curling of the polarizing plate was improved, but bubbles were formed during the production of the polarizing plate.
When PET having a smaller phase difference than Comparative Example 2 was used, it was found that rainbow-like unevenness was observed and the curling of the polarizing plate was also deteriorated.
From the results of Example 4, it was found that even the PET film with a hard coat layer can suppress the curling of the polarizing plate according to the present invention.
Even if the film thickness of the first protective film is thinner than in Examples 5 and 6, curling of the polarizing plate can be suppressed according to the present invention. It turns out that it becomes easy to be visually recognized.
From Example 7, it was found that even the PET film produced by coextrusion can suppress the curling of the polarizing plate according to the present invention.
From Examples 8 and 9, it was found that the curling of the polarizing plate can be suppressed by the present invention even when the second protective film is an acrylic resin or a cellulose resin.
From Comparative Example 3, it was found that when the upper limit of the range of the formula (2) was exceeded (the moment due to the curing shrinkage force ratio between the adhesive layers 1 and 2), the curling of the polarizing plate was increased.

1 First Protective Film 2 Polarizer 3 Second Protective Film 11 Adhesive Layer 1
12 Adhesive layer 2
13 Neutral axis 14 Easy adhesion layer 15 Hard coat layer 20 Polarizing plate 21 Viewing side polarizing plate 22 Liquid crystal cell 23 Backlight side polarizing plate 23a Backlight side polarizing plate protective film 23b Backlight side polarizing plate polarizer 26 Backlight 30 Image display device S ₁ Curing shrinkage force at the time of bonding of the polarizing plate _{1 of the} adhesive layer 1 ₂ Curing shrinkage force at the time of bonding of the polarizing plate of the adhesive layer 2 UV active energy ray irradiation direction y ₁ Film thickness y of the first protective film ₂ Second protective film thickness y ₃ Polarizer thickness η Neutral axis

Claims

A polarizer having polarization performance;
A first protective film bonded to one surface of the polarizer via an adhesive layer 1;
A second protective film bonded to the other surface of the polarizer via the adhesive layer 2,
The in-plane retardation of the first protective film is 3000 nm or more,
Satisfy at least one of the following formulas (A) and (B),
A polarizing plate satisfying the following formula (2).
E 1 ≠ E 3 ... Formula (A)
y 1 ≠ y 3 ... Formula (B)

(In the formulas (A), (B), (1) and (2), E 1 represents the elastic modulus (unit: GPa) of the first protective film, and y 1 represents the film thickness of the first protective film ( (Unit: μm), E 2 represents the elastic modulus (unit: GPa) of the polarizer, y 2 represents the film thickness (unit: μm) of the polarizer, and E 3 represents the elastic modulus of the second protective film. Y 3 represents the film thickness (unit: μm) of the second protective film, S 1 represents the curing shrinkage force when the adhesive layer 1 is bonded to the polarizing plate, and S 2 is the polarizing plate of the adhesive layer 2 Represents the curing shrinkage force at the time of bonding,

Is the integral over the entire film thickness of the polarizing plate, y is the coordinate taken in the direction of the polarizer from the top surface of the first protective film, and E (y) is the elastic modulus (unit: GPa) of the member at that coordinate.
The polarizing plate according to claim 1, wherein the adhesive layer 1 and the adhesive layer 2 include an adhesive that is cured by active energy rays.
The polarizing plate according to claim 1 or 2, wherein the adhesive layer 1 and the adhesive layer 2 have a thickness of 0.5 to 5 µm.
The polarizing plate according to any one of claims 1 to 3, wherein the first protective film contains a polyester resin or a polycarbonate resin as a main component.
The polarizing plate according to any one of claims 1 to 4, wherein an easy-adhesion layer and a hard coat layer are disposed on the first protective film.
The polarizing plate according to any one of claims 1 to 5, the elastic modulus E 3 of the polarizer is 10 ~ 30 GPa.
A step of bonding a first protective film having an in-plane retardation of 3000 nm or more to one surface of a polarizer having polarization performance through the adhesive layer 1;
A step of bonding a second protective film to the other surface of the polarizer via an adhesive layer 2 controlled to a film thickness different from that of the adhesive layer 1;
The method for producing a polarizing plate according to any one of claims 1 to 6, further comprising a step of curing and shrinking the adhesive layer 1 and the adhesive layer 2.
The adhesive layer 1 and the adhesive layer 2 include an adhesive that is cured by active energy rays,
The method for producing a polarizing plate according to claim 7, wherein the step of curing and shrinking the adhesive layer 1 and the adhesive layer 2 is a step of irradiating active energy rays to simultaneously cure the adhesive layer 1 and the adhesive layer 2.
The adhesive layer 1 and the adhesive layer 2 include an adhesive that is cured by ultraviolet rays,
The first protective film contains an ultraviolet absorber;
The step of curing and shrinking the adhesive layer 1 and the adhesive layer 2 is a step of irradiating ultraviolet rays from the second protective film side to simultaneously cure the adhesive layer 1 and the adhesive layer 2. The manufacturing method of the polarizing plate of description.
The method for producing a polarizing plate according to any one of claims 7 to 9, wherein the compositions of the adhesive layer 1 and the adhesive layer 2 are the same.
An image display device comprising the polarizing plate according to any one of claims 1 to 6.