JP2016012021A - Polarizing plate protective film, polarizing plate, image display device, and manufacturing method of polarizing plate protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate protective film having excellent hardness, brittleness, and interlayer adhesiveness, little coloring, and low moisture permeability, a polarizing plate and an image display device having the polarizing plate protective film, and a method for manufacturing the polarizing plate protective film.SOLUTION: The polarizing plate protective film includes a cellulose ester support and a low moisture-permeable hard coat layer. The low moisture-permeable hard coat layer is formed from a composition for a low moisture-permeable hard coat layer comprising the following components (A) and (B), in which the content of (A) is 70 mass% or more with respect to the whole solid content in the composition for a low moisture-permeable hard coat layer. The components are: (A) a polyfunctional epoxy monomer having two or more epoxy rings and one or more cyclic skeletons other than an epoxy ring in one molecule and having a molecular weight of 270 or less; and (B) a photo-cation polymerization initiator.

Description

  The present invention relates to a polarizing plate protective film, a polarizing plate, an image display device, and a method for producing a polarizing plate protective film that have excellent hardness, brittleness, and interlayer adhesion, low moisture permeability, and little coloration.

  In recent years, liquid crystal display devices have been widely used for liquid crystal panels such as liquid crystal televisions, personal computers, mobile phones, and digital cameras. Usually, a liquid crystal display device has a liquid crystal panel member provided with polarizing plates on both sides of a liquid crystal cell, and display is performed by controlling light from the backlight member with the liquid crystal panel member. Here, a polarizing plate consists of a polarizer and its protective film, and a general polarizer is obtained by dyeing a stretched polyvinyl alcohol (PVA) film with iodine or a dichroic dye, and as a protective film. Cellulose ester film or the like is used.

  Recent liquid crystal display devices are becoming more and more demanding, and the demands for durability are becoming stricter as the quality of the liquid crystal display devices increases. The durability is required to be excellent in hardness and brittleness of the protective film on the surface, and to have good adhesion between the protective film and the support or other layers. In addition, for example, when used in outdoor applications, stability against environmental changes is required, and optical films such as polarizing plate protective films and optical compensation films used in liquid crystal display devices also have dimensions and optical characteristics with respect to temperature and humidity changes. It is required to suppress changes in

In Patent Document 1, a curable composition containing a compound having a specific cycloaliphatic hydrocarbon group and having two unsaturated double bond groups in the molecule is applied on a transparent substrate film and cured. A low moisture-permeable film having a cured layer obtained by heating and having a moisture permeability of about 321 g / m ² / day is described.

  Moreover, the resin composition using the 2 types of different compound which has a reactive functional group is disclosed as a composition for electronic devices as which low moisture permeability is requested | required, such as organic electroluminescence, electronic paper, and a solar cell ( Patent Document 2). Patent Document 2 describes a compound using a compound having a cyclohexane ring and two epoxy groups on one of two different compounds.

  Patent Document 3 discloses an antireflection material that has excellent wear resistance and chemical resistance as well as excellent antireflection properties and image contrast as a material used for an image display device or the like. ing. The antireflection material is provided with a roughened layer. As the roughened layer forming composition, a mixture of a polyfunctional epoxy monomer and a polyfunctional acrylate monomer or an epoxy resin is used.

JP 2006-083225 A International Publication No. 2012/020688 JP 11-287902 A

The resin composition described in Patent Document 2 is used as a sealing material or a sealing agent for electronic devices. Patent Document 2 does not have a study as a polarizing plate protective film, and has hardness, brittleness, and interlayer. No consideration has been given to the adhesiveness and coloring of the.
In Patent Document 3, low moisture permeability is not studied.
In particular, when the polyfunctional epoxy monomer and the polyfunctional acrylate monomer are used in combination by the inventors' investigation, the polymerization of the polyfunctional acrylate monomer proceeds first, the viscosity of the composition increases, and the collision frequency of the monomer increases. Therefore, when the content of the polyfunctional epoxy monomer is less than 70% by mass with respect to the hard coat layer forming composition, the resulting layer has a moisture permeability. It was found that the hardness was low, the hardness was low, and the brittleness was poor.
In addition, when a compound having a molecular weight of greater than 270 is used as the polyfunctional epoxy monomer, the connecting chain length between crosslinks in the polymer is increased, so that the resulting layer is low in hardness and inferior in brittleness. It was found that the adhesion to the body was inferior.

Therefore, the object of the present invention is hardness, brittleness, and adhesion between layers (adhesion between a low moisture permeability hard coat layer and a cellulose ester support, or adhesion between a low moisture permeability hard coat layer and another layer). An object of the present invention is to provide a polarizing plate protective film that is excellent, has little coloring, and low moisture permeability.
Another object of the present invention is to provide a polarizing plate and an image display device using the polarizing plate protective film.

  The problem to be solved by the present invention can be solved by the present invention which is the following means.

上記一般式（１）中、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４及びＲ_５は、それぞれ独立に、水素原子、メチル基又はエチル基を表す。
Ｘは、単結合、又は置換基を有しても良いアルキレン基、置換基を有しても良いアリーレン基、置換基を有しても良いアラルキレン基、エステル結合、エーテル結合、複素環を含む連結基、若しくはこれらの組み合わせからなる（ｍ＋ｎ）価の連結基を表す。
ｍ及びｎは、それぞれ独立に０以上２以下の整数を表し、ｍ＋ｎ≧２である。
Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４及びＲ_５が複数存在する場合、複数のＲ_１、複数のＲ_２、複数のＲ_３、複数のＲ_４及び複数のＲ_５は、それぞれ同じでも異なっていてもよい。
＜４＞
上記（Ａ）が下記一般式（２）で表される化合物である＜１＞〜＜３＞のいずれかに記載の偏光板保護フィルム。
一般式（２）

上記一般式（２）中、Ｒ_６、Ｒ_７、Ｒ_８及びＲ_９は、それぞれ独立に、水素原子、メチル基又はエチル基を表す。
Ｙは、単結合、又は置換基を有しても良いアルキレン基、置換基を有しても良いアリーレン基、置換基を有しても良いアラルキレン基、エステル結合、エーテル結合、複素環を含む連結基、若しくはこれらの組み合わせからなる２価の連結基を表す。
＜５＞
上記低透湿性ハードコート層用組成物が、更に無機フィラーを含む＜１＞〜＜４＞のいずれかに記載の偏光板保護フィルム。
＜６＞
上記低透湿性ハードコート層の膜厚が３μｍ以上３０μｍ以下である＜１＞〜＜５＞のいずれかに記載の偏光板保護フィルム。
＜７＞
上記セルロースエステル支持体と上記低透湿性ハードコート層との間に、上記セルロースエステル支持体と上記低透湿性ハードコート層とが混合した混合層を有し、上記混合層の厚みが０．１μｍ以上３μｍ以下である＜１＞〜＜６＞のいずれかに記載の偏光板保護フィルム。
＜８＞
偏光子と、上記偏光子の少なくとも一方の面に保護フィルムとして設けられた＜１＞〜＜７＞のいずれかに記載の偏光板保護フィルムとを含む偏光板。
＜９＞
液晶セルと、上記液晶セルの少なくとも一方の面に配置された＜８＞に記載の偏光板とを含む画像表示装置。
＜１０＞
セルロースエステル支持体と低透湿性ハードコート層とを有する偏光板保護フィルムの製造方法であって、
上記低透湿性ハードコート層を、下記（Ａ）及び（Ｂ）を含む低透湿性ハードコート層用組成物から形成し、
下記（Ａ）の含有量は、上記低透湿性ハードコート層用組成物中の全固形分に対して７０質量％以上である、偏光板保護フィルムの製造方法。
（Ａ）１分子中に、２つ以上のエポキシ環と１つ以上のエポキシ環以外の環状骨格とを有する、分子量が２７０以下である、多官能エポキシモノマー
（Ｂ）光カチオン重合開始剤
＜１１＞
上記セルロースエステル支持体上に上記低透湿性ハードコート層用組成物を塗布した後、紫外線を照射することにより上記低透湿性ハードコート層を作製する＜１０＞に記載の偏光板保護フィルムの製造方法。
＜１２＞
上記低透湿性ハードコート層用組成物を塗布したセルロースエステル支持体を加温した状態で、紫外線を照射することにより上記低透湿性ハードコート層を作製する＜１１＞に記載の偏光板保護フィルムの製造方法。
＜１３＞
上記紫外線を照射した後、加熱せずに上記低透湿性ハードコート層を作製する＜１１＞又は＜１２＞に記載の偏光板保護フィルムの製造方法。 <1>
A polarizing plate protective film having a cellulose ester support and a low moisture permeability hard coat layer,
The low moisture-permeable hard coat layer is formed from a composition for low moisture-permeable hard coat layer containing the following (A) and (B):
Content of following (A) is a polarizing plate protective film which is 70 mass% or more with respect to the total solid in the said composition for low moisture-permeable hard-coat layers.
(A) Multifunctional epoxy monomer having two or more epoxy rings and one or more cyclic skeletons other than epoxy rings in one molecule, and having a molecular weight of 270 or less (B) Photocationic polymerization initiator <2 >
The polarizing plate protective film according to <1>, wherein the cyclic skeleton other than the epoxy ring is a cyclohexane ring.
<3>
The polarizing plate protective film according to <1> or <2>, wherein (A) is a compound represented by the following general formula (1).
General formula (1)

In the general formula (1), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom, a methyl group or an ethyl group.
X includes a single bond or an alkylene group that may have a substituent, an arylene group that may have a substituent, an aralkylene group that may have a substituent, an ester bond, an ether bond, or a heterocyclic ring. A (m + n) -valent linking group comprising a linking group or a combination thereof is represented.
m and n each independently represent an integer of 0 or more and 2 or less, and m + n ≧ 2.
When there are a plurality of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ , the plurality of R ₁ , the plurality of R ₂ , the plurality of R ₃ , the plurality of R ₄ and the plurality of R ₅ are the same or different. It may be.
<4>
The polarizing plate protective film according to any one of <1> to <3>, wherein (A) is a compound represented by the following general formula (2).
General formula (2)

In the general formula (2), R ₆ , R ₇ , R ₈ and R ₉ each independently represent a hydrogen atom, a methyl group or an ethyl group.
Y includes a single bond or an alkylene group that may have a substituent, an arylene group that may have a substituent, an aralkylene group that may have a substituent, an ester bond, an ether bond, and a heterocyclic ring. A divalent linking group comprising a linking group or a combination thereof is represented.
<5>
The polarizing plate protective film according to any one of <1> to <4>, wherein the composition for a low moisture permeability hard coat layer further contains an inorganic filler.
<6>
The polarizing plate protective film according to any one of <1> to <5>, wherein the film thickness of the low moisture permeability hard coat layer is 3 μm or more and 30 μm or less.
<7>
Between the cellulose ester support and the low moisture-permeable hard coat layer, there is a mixed layer in which the cellulose ester support and the low moisture-permeable hard coat layer are mixed, and the thickness of the mixed layer is 0.1 μm. The polarizing plate protective film according to any one of <1> to <6>, which is 3 μm or less.
<8>
The polarizing plate containing a polarizer and the polarizing plate protective film in any one of <1>-<7> provided as a protective film in the at least one surface of the said polarizer.
<9>
An image display device comprising: a liquid crystal cell; and the polarizing plate according to <8> disposed on at least one surface of the liquid crystal cell.
<10>
A method for producing a polarizing plate protective film having a cellulose ester support and a low moisture permeability hard coat layer,
The low moisture-permeable hard coat layer is formed from a composition for low moisture-permeable hard coat layer containing the following (A) and (B):
Content of following (A) is a manufacturing method of the polarizing plate protective film which is 70 mass% or more with respect to the total solid in the said composition for low moisture-permeable hard-coat layers.
(A) Multifunctional epoxy monomer having two or more epoxy rings and one or more cyclic skeletons other than epoxy rings in one molecule and having a molecular weight of 270 or less (B) Photocationic polymerization initiator <11 >
After manufacturing the said composition for low moisture-permeable hard-coat layers on the said cellulose-ester support body, producing the said low moisture-permeable hard-coat layer by irradiating with an ultraviolet-ray manufacture of the polarizing plate protective film as described in <10> Method.
<12>
The polarizing plate protective film according to <11>, wherein the low moisture-permeable hard coat layer is produced by irradiating ultraviolet rays while the cellulose ester support coated with the low moisture-permeable hard coat layer composition is heated. Manufacturing method.
<13>
The manufacturing method of the polarizing plate protective film as described in <11> or <12> which produces the said low moisture-permeable hard-coat layer, after irradiating the said ultraviolet-ray, without heating.

  According to the present invention, it is possible to provide a polarizing plate protective film that is excellent in hardness, brittleness, and interlayer adhesion, has little coloration, and has low moisture permeability. Moreover, according to this invention, the polarizing plate using the said polarizing plate protective film and an image display apparatus can be provided.

  Hereinafter, preferred embodiments of the polarizing plate protective film, 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 addition, in this specification, when a numerical value represents a physical property value, a characteristic value, etc., the description “(numerical value 1) to (numerical value 2)” means “(numerical value 1) or more and (numerical value 2) or less”.

The polarizing plate protective film of the present invention is a polarizing plate protective film having a cellulose ester support and a low moisture permeability hard coat layer,
The low moisture-permeable hard coat layer is formed from a composition for low moisture-permeable hard coat layer containing the following (A) and (B):
Content of following (A) is 70 mass% or more with respect to the total solid in the composition for low moisture-permeable hard-coat layers.
(A) Multifunctional epoxy monomer having two or more epoxy rings and one or more cyclic skeletons other than epoxy rings in one molecule and having a molecular weight of 270 or less (B) Photocationic polymerization initiator

  Even if the polarizing plate protective film of the present invention has a low moisture-permeable hard coat layer directly on the cellulose ester support, it has a low moisture-permeable hard coat layer via another layer on the cellulose ester support. It may be a thing.

[(A) polyfunctional epoxy monomer]
In the present invention, (A) the polyfunctional epoxy monomer has two or more epoxy rings and one or more cyclic skeletons other than the epoxy ring in one molecule, and has a molecular weight of 270 or less. And content of (A) is 70 mass% or more with respect to the total solid in the composition for low moisture-permeable hard-coat layers.
When the molecular weight of the polyfunctional epoxy monomer is 270 or less, the molecular weight between crosslinks in the polymer can be reduced, and the moisture permeability can be lowered. The molecular weight of the polyfunctional epoxy monomer is preferably 140 or more and 260 or less.

The content of (A) is preferably 70% by mass or more with respect to the total solid content in the composition for low moisture permeability hard coat layer, from the viewpoint that both low moisture permeability and high hardness can be achieved. As for content of (A), it is more preferable that it is 80 mass% or more, and it is still more preferable that it is 85 mass% or more.
Moreover, from the reason of ensuring sclerosis | hardenability, it is preferable that content of (A) is 99.5 mass% or less, and it is more preferable that it is 99 mass% or less.

  (A) The polyfunctional epoxy monomer preferably has 2 to 3 epoxy rings in one molecule, and more preferably has 2 epoxy rings.

  (A) As cyclic skeletons other than the epoxy ring which a polyfunctional epoxy monomer has, cycloalkane rings, such as a cyclohexane ring, a cyclopentane ring, a cyclooctane ring, a bicycloheptane ring, are preferable, and a cyclohexane ring is more preferable. Further, the cyclic skeleton other than the epoxy ring may be condensed with the epoxy ring.

(A) As a polyfunctional epoxy monomer, it is preferable that it is a compound represented by following General formula (1).
General formula (1)

In the general formula (1), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom, a methyl group or an ethyl group.
X includes a single bond or an alkylene group that may have a substituent, an arylene group that may have a substituent, an aralkylene group that may have a substituent, an ester bond, an ether bond, or a heterocyclic ring. A (m + n) -valent linking group comprising a linking group or a combination thereof is represented.
m and n each independently represent an integer of 0 or more and 2 or less, and m + n ≧ 2.
When there are a plurality of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ , the plurality of R ₁ , the plurality of R ₂ , the plurality of R ₃ , the plurality of R ₄ and the plurality of R ₅ are the same or different. It may be.

R ₁ , R ₂ , R ₃ , R ₄ and R ₅ each independently preferably represent a hydrogen atom or a methyl group, and more preferably all represent a hydrogen atom.

X includes a single bond or an alkylene group that may have a substituent, an arylene group that may have a substituent, an aralkylene group that may have a substituent, an ester bond, an ether bond, or a heterocyclic ring. A (m + n) -valent linking group comprising a linking group or a combination thereof is represented.
Examples of the alkylene group include a linear, branched or cyclic alkylene group, an alkylene group having 1 to 10 carbon atoms is preferable, and an alkylene group having 1 to 8 carbon atoms is more preferable. Specific examples include a methylene group, a propylene group, and a cyclohexylene group.
As the arylene group, an arylene group having 6 to 12 carbon atoms is preferable, and a phenylene group and a fluorene group are preferable.
As the aralkylene group, an alkylene group composed of a preferable range of the alkylene group and a preferable range of the arylene group is preferable.
As the linking group containing a heterocyclic ring, a linking group containing a xanthene skeleton or a carbazole skeleton is preferable.

  The alkylene group, arylene group, aralkylene group or heterocyclic ring represented by X may have a substituent, and examples of the substituent include an alkyl group, an alkoxy group, an acyl group, an acyloxy group, and an alkoxycarbonyl group.

  X is preferably a single bond, an alkylene group, an ester bond, an ether bond, a linking group consisting of an alkylene group and an ester bond, or a linking group consisting of an alkylene group and an ether bond.

  m is preferably 1 or 2, and n is preferably 0 or 1. m + n is preferably 2 or 3.

The polyfunctional epoxy monomer represented by the general formula (1) is more preferably a compound represented by the following general formula (2).
General formula (2)

In the general formula (2), R ₆ , R ₇ , R ₈ and R ₉ each independently represent a hydrogen atom, a methyl group or an ethyl group.
Y has a single bond or an alkylene group which may have a substituent, an arylene group which may have a substituent, an aralkylene group which may have a substituent, an ester bond, an ether bond or a substituent. Or a divalent linking group composed of a combination thereof.

Preferable ranges of R ₆ , R ₇ , R ₈ and R ₉ are the same as R ₁ , R ₂ , R ₃ , R ₄ and R _{5 in} the general formula (1).
The preferable range of Y is the same as X of General formula (1).

  Specific examples of the polyfunctional epoxy monomer represented by the general formula (A) are listed below, but are not limited thereto.

[(B) Photocationic polymerization initiator]
The epoxy ring of the (A) polyfunctional epoxy monomer causes a polymerization reaction when irradiated with active energy in the presence of a photocationic polymerization initiator. As the photocationic polymerization initiator, sulfonium salts, iodonium salts, diazonium salts and the like can be used. Specifically, “Irgacure 290 (trade name, BASF)”, “Irgacure 250 (same)”, “Irgacure”. 270 (same) "," CPI-100P (trade name, San Apro) "," CPI-101A (same) "," CPI-200K (same) "," CPI-210S (same) ", etc. Can do.

  The content of the cationic photopolymerization initiator is 0 with respect to the total solid content in the composition for a low moisture-permeable hard coat layer because the epoxy ring is polymerized and the starting point is set so as not to increase too much. 5-8 mass% is preferable, and 1-5 mass% is more preferable.

[Cellulose ester support]
As a cellulose-ester support body in this invention, the well-known film, board, sheet | seat etc. which consist of cellulose esters can be used, and there is no limitation in particular. As the cellulose ester film, a cellulose acylate film (for example, a cellulose triacetate film (refractive index 1.48), a cellulose diacetate film, a cellulose acetate butyrate film, a cellulose acetate propionate film) or the like can be used.

  By using the cellulose ester support, the epoxy monomer penetrates into the cellulose ester support, so that the adhesion between the layers is improved. Among them, a cellulose acylate film having high transparency, optically low birefringence, easy production, and generally used as a protective film for a polarizing plate is preferable, and a cellulose triacetate film is more preferable. Moreover, the thickness of a support body shall be about 20 micrometers-about 1000 micrometers normally. In the present invention, it is particularly preferable that the support is a cellulose ester film, and the film thickness of the cellulose ester film is 20 μm or more and 70 μm or less.

  The support in the present invention preferably has higher transparency, and preferably has a visible light transmittance of 80% or more.

In the present invention, it is preferable to use cellulose acetate having an acetylation degree of 59.0 to 61.5% as the cellulose acylate film.
The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The degree of acetylation follows the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like). The viscosity average degree of polymerization (DP) of cellulose acylate is preferably 250 or more, and more preferably 290 or more.
In addition, the cellulose acylate used in the present invention has a Mw / Mn (Mw is a weight average molecular weight, Mn is a number average molecular weight) value by gel permeation chromatography close to 1.0, in other words, a molecular weight distribution. Narrow is preferred. The specific value of Mw / Mn is preferably 1.0 to 1.7, more preferably 1.3 to 1.65, and most preferably 1.4 to 1.6. preferable.

In general, the 2, 3, and 6 hydroxyl groups of cellulose acylate are not evenly distributed by 1/3 of the total substitution degree, and the substitution degree of the 6-position hydroxyl group tends to be small. In the present invention, it is preferable that the substitution degree of the 6-position hydroxyl group of cellulose acylate is larger than that of the 2- and 3-positions. The hydroxyl group at the 6-position with respect to the total substitution degree is preferably substituted with 32% or more of an acyl group, more preferably 33% or more, and particularly preferably 34% or more. Furthermore, the substitution degree of the 6-position acyl group of cellulose acylate is preferably 0.88 or more. The 6-position hydroxyl group may be substituted with a propionyl group, butyroyl group, valeroyl group, benzoyl group, acryloyl group or the like, which is an acyl group having 3 or more carbon atoms, in addition to the acetyl group. The degree of substitution at each position can be determined by NMR.
In the present invention, as cellulose acylate, paragraphs “0043” to “0044” [Example] [Synthesis Example 1], paragraphs “0048” to “0049” [Synthesis Example 2], and paragraph “ Cellulose acetate obtained by the method described in “0051” to “0052” [Synthesis Example 3] can be used.

  The composition for forming a low moisture-permeable hard coat layer of the present invention may further contain a solvent, an inorganic filler, an ultraviolet absorber, and a surfactant as necessary. Hereinafter, each component will be described.

〔solvent〕
The composition for forming a low moisture-permeable hard coat layer can contain a solvent. As the solvent, various solvents can be used in consideration of the solubility of the monomer, the drying property during coating, the dispersibility of the translucent particles, and the like. Examples of such organic solvents include dibutyl ether, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole, phenetole, and dimethyl carbonate. , Methyl ethyl carbonate, diethyl carbonate, acetone, methyl ethyl ketone (MEK), diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, acetic acid Propyl, methyl propionate, ethyl propionate, γ-ptyrolactone, methyl 2-methoxyacetate, methyl 2-ethoxyacetate, ethyl 2-ethoxyacetate, ethyl 2-ethoxypropionate, 2 Methoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1,2-diacetoxyacetone, acetylacetone, diacetone alcohol, methyl alcohol such as methyl acetoacetate and ethyl acetoacetate, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, cyclohexyl Alcohol, isobutyl acetate, methyl isobutyl ketone (MiBK), 2-octanone, 2-pentanone, 2-hexanone, ethylene glycol ethyl ether, ethylene glycol isopropyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, ethyl carbitol, butyl carbitol , Hexane, heptane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, benzene , Toluene, xylene and the like, and can be used alone or in combination of two or more.

Of the above solvents, it is preferable to use at least one of methyl acetate, ethyl acetate, methyl ethyl ketone, acetylacetone, acetone, cyclohexanone, toluene, and xylene.
Especially, it is preferable to use at least 1 sort (s) among methyl acetate, methyl ethyl ketone, acetone, and cyclohexanone from a viewpoint that it has the permeability | transmittance to a cellulose-ester support body.

  It is preferable to use a solvent so that the solid content in the composition for forming a low moisture-permeable hard coat layer is in the range of 20 to 80% by mass, more preferably 30 to 75% by mass, and still more preferably 40. -70 mass%.

[Inorganic filler]
In the present invention, it is preferable that the low moisture-permeable hard coat layer composition further contains an inorganic filler. It is preferable that the type and amount of the inorganic filler to be used be adjusted according to the required refractive index, film strength, film thickness, coatability, and the like.
The shape of the inorganic filler used in the present invention is not particularly limited, and for example, any of a spherical shape, a plate shape, a fiber shape, a rod shape, an indefinite shape, a hollow shape, and the like is preferably used. Further, the kind of the inorganic filler is not particularly limited, but an amorphous one is preferably used, and is preferably made of a metal oxide, nitride, sulfide or halide. Particularly preferred is silica. As metal atoms, Na, K, Mg, Ca, Ba, Al, Zn, Fe, Cu, Ti, Sn, In, W, Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si, B Bi, Mo, Ce, Cd, Be, Pb, Ni and the like. In order to obtain a transparent cured film, the average particle diameter of the inorganic filler is preferably set to a value within the range of 0.001 to 0.2 μm, more preferably 0.001 to 0.1 μm, and still more preferably. 0.001 to 0.06 μm. Here, the average particle diameter of the particles is measured by a Coulter counter.
Although the usage method of the inorganic filler in this invention is not restrict | limited in particular, For example, it can use in a dry state or can also be used in the state disperse | distributed to water or the organic solvent.

[Ultraviolet absorber]
The polarizing plate protective film of the present invention can be used for a polarizing plate or an image display device member. From the viewpoint of preventing deterioration of a polarizing plate or a liquid crystal cell, ultraviolet light is contained in the composition for forming a low moisture-permeable hard coat layer. By containing an absorbent, the polarizing plate protective film can be provided with ultraviolet absorptivity.
A well-known thing can be used as a ultraviolet absorber. For example, the ultraviolet absorber as described in Unexamined-Japanese-Patent No. 2001-72782 and Special Table 2002-543265 is mentioned.

  As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Only one type of ultraviolet absorber may be used, or two or more types may be used in combination. For example, the ultraviolet absorber as described in Unexamined-Japanese-Patent No. 2001-72782 and Special Table 2002-543265 is mentioned. Specific examples of the ultraviolet absorber include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like.

[Translucent resin particles]
The composition for forming a low moisture permeability hard coat layer of the present invention may contain translucent resin particles (also referred to as light diffusion particles). By including translucent particles in the composition for forming a low moisture-permeable hard coat layer, the surface of the low moisture-permeable hard coat layer can be provided with an uneven shape or an internal haze.
The average particle diameter of the translucent resin particles is 1.0 μm or more and 3.0 μm or less, preferably 1.2 μm or more and 2.8 μm or less, more preferably 1.4 μm or more and 2.6 μm or less. In the present invention, the average particle size indicates the primary particle size. If the average particle size is 1.0 μm or more, the surface unevenness of the low moisture permeability hard coat layer can be appropriately increased by controlling the aggregation of the particles, and the antiglare property is exhibited. Moreover, when it is a particle | grain with an average particle diameter of 3.0 micrometers or less, when it is going to form a desired surface shape, it is not necessary to make the thickness of a low moisture-permeable hard-coat layer too thick, and a curl and a brittle fall can be suppressed.
It is also preferable to use two or more kinds of particles having different average particle diameters as means for adjusting the surface irregularity shape to a specific range.

The measuring method of the particle diameter of the translucent resin particles may be any measuring method as long as it is a measuring method for measuring the particle diameter of the particles. However, the particle size distribution of the particles is measured by the Coulter counter method, and the measured distribution is measured. Is calculated from the particle distribution obtained by converting to a particle number distribution, or the particles are observed with a transmission electron microscope (magnification of 500,000 to 2,000,000 times), and 100 particles are observed. There is a method of obtaining an average particle size.
In the present invention, the average particle diameter is a value obtained by the Coulter counter method.

  In order to make the uneven surface shape in the low moisture-permeable hard coat layer of the present invention, the ratio of the film thickness of the low moisture-permeable hard coat layer to the average particle diameter of the light-transmitting resin particles (the film thickness of the low moisture-permeable hard coat layer) / Average particle diameter of the translucent resin particles) is preferably designed to be 1.0 to 2.0, more preferably 1.1 to 1.9, and still more preferably 1.2 to 1.8. When this ratio is 1.0 or more, the unevenness of the film surface does not become too large, which is excellent in terms of black tightening and point defects. On the other hand, if it is 2.0 or less, it is not necessary to add a large amount of particles in order to achieve the desired antiglare property, which is excellent from the viewpoint of the hardness of the film.

The uneven surface shape of the low moisture-permeable hard coat layer is preferably designed so that the arithmetic average roughness Ra is 0.01 to 0.25 μm, more preferably 0.01 to 0.20 μm, still more preferably 0.01 to 0.15 μm. When the Ra value is 0.01 μm or more, clear antiglare properties are obtained, while when the Ra value is 0.25 μm or less, high black tightening is exhibited.
The haze value in the low moisture-permeable hard coat layer of the present invention is preferably designed to be 0.5 to 5.0%, more preferably 1.5 to 4.5%, and 2.5% to 4 More preferably, it is made 0.0%. By designing the haze within this range, it is possible to achieve both excellent anti-glare properties and black tightening properties.

  The refractive index of the translucent resin particles was changed by changing the mixing ratio of two kinds of solvents having different refractive indexes selected from methylene iodide, 1,2-dibromopropane, and n-hexane. The turbidity is measured by dispersing an equal amount of translucent particles in a solvent, and the refractive index of the solvent when the turbidity is minimized is measured by an Abbe refractometer.

  The light-transmitting resin particles can impart internal scattering properties by controlling the difference in refractive index with the binder. However, since the contrast decreases when the internal scattering properties are large, the light-transmitting resin particles are excluded. It is preferable to design the difference between the refractive index of the antiglare layer to 0.010 or less, the refractive index difference between the translucent resin particles and the binder is 0.01 or less, preferably 0.005 or less, More preferably 0. By setting the difference in refractive index within this range, it is possible to substantially eliminate a decrease in contrast due to internal scattering.

  Specific examples of the translucent resin particles include, for example, crosslinked polymethyl methacrylate particles, crosslinked methyl methacrylate-styrene copolymer particles, crosslinked polystyrene particles, crosslinked methyl methacrylate-methyl acrylate copolymer particles, and crosslinked acrylate-styrene copolymers. Examples thereof include resin particles such as particles, melamine / formaldehyde resin particles, and benzoguanamine / formaldehyde resin particles. Of these, crosslinked styrene particles, crosslinked polymethyl methacrylate particles, crosslinked methyl methacrylate-styrene copolymer particles and the like are preferable. Furthermore, the surface of these resin particles is surface-modified particles in which a compound containing fluorine atom, silicon atom, carboxyl group, hydroxyl group, amino group, sulfonic acid group, phosphoric acid group or the like is chemically bonded, or nano-sized such as silica or zirconia. Examples of the particles include inorganic fine particles bonded to the surface.

  The translucent resin particles used in the present invention may be one type or two or more types. The content of the translucent resin particles is 0.5 to 12% by mass with respect to the total solid content in the composition for forming a low moisture-permeable hard coat layer, from the viewpoint of imparting antiglare properties and high blackness, 1-10 mass% is preferable and 2-8 mass% is more preferable.

In the polarizing plate protective film of the present invention, the low moisture permeability hard coat layer is prepared by applying a composition for low moisture permeability hard coat layer on a cellulose ester support and then irradiating with ultraviolet rays. Is preferred. Under the present circumstances, it is preferable that the illumination intensity of an ultraviolet-ray is 10-5000mW / cm < ² >, and it is preferable that an irradiation amount is 10-10000mJ / cm < ² >.

  Moreover, it is preferable that a low moisture-permeable hard-coat layer irradiates an ultraviolet-ray in the state which set the cellulose-ester support body which apply | coated the composition for low moisture-permeable hard-coat layers to 10-90 degreeC, The state set to 30-90 degreeC It is more preferable to irradiate with ultraviolet rays. By setting the temperature within this range, the polymerizability can be increased. You may heat in order to make it in this temperature range. The temperature can be measured with PT-2LD manufactured by OPTEX.

  Furthermore, the low moisture-permeable hard coat layer in the present invention can be heated after being irradiated with ultraviolet rays, but from the viewpoint of complexity of the process and suppression of damage to the support and other layers, after irradiation with ultraviolet rays. It is preferable that it is produced without heating.

[Production method of polarizing plate protective film]
The method for producing a polarizing plate protective film of the present invention is a method for producing a polarizing plate protective film having a cellulose ester support and a low moisture-permeable hard coat layer,
A low moisture-permeable hard coat layer is formed from the composition for low moisture-permeable hard coat layer containing the following (A) and (B):
Content of following (A) is a manufacturing method of the polarizing plate protective film which is 70 mass% or more with respect to the total solid in the composition for low moisture-permeable hard-coat layers.
(A) Multifunctional epoxy monomer having two or more epoxy rings and one or more cyclic skeletons other than epoxy rings in one molecule and having a molecular weight of 270 or less (B) Photocationic polymerization initiator

In the method for producing a polarizing plate protective film of the present invention, it is preferable to prepare a low moisture-permeable hard coat layer by irradiating ultraviolet rays after applying the composition for a low moisture-permeable hard coat layer on a cellulose ester support. . Under the present circumstances, it is preferable that the illumination intensity of an ultraviolet-ray is 10-5000mW / cm < ² >, and it is preferable that an irradiation amount is 10-10000mJ / cm < ² >.

  In the method for producing a polarizing plate protective film of the present invention, a low moisture-permeable hard coat layer is produced by irradiating ultraviolet rays in a heated state of a cellulose ester support coated with the composition for low moisture-permeable hard coat layer. It is also preferable. At this time, the temperature of the support is preferably 10 to 90 ° C. In order to increase the polymerizability, it is preferable that the film is exposed in a heated state.

  In the manufacturing method of the polarizing plate protective film of the present invention, from the viewpoint of complexity of the process and suppression of damage to the support and other layers, the low moisture permeability hard coat layer is produced without heating after irradiation with ultraviolet rays. It is preferable to do.

<Functional layer>
The polarizing plate protective film in the present invention may further have another functional layer. The type of the functional layer is not particularly limited, but an antireflection layer (a layer having a refractive index adjusted such as a low refractive index layer, a medium refractive index layer, a high refractive index layer), an antiglare layer, an antistatic layer, an ultraviolet absorbing layer, An adhesion layer (a layer that improves adhesion between the support and the low moisture-permeable hard coat layer) can be used.
The functional layer may be a single layer or a plurality of layers. The method for laminating the functional layers is not particularly limited.
The functional layer may be laminated on the surface on which the low moisture-permeable hard coat layer of the present invention is not laminated.

{Antireflection layer}
In the present invention, an antireflection layer may be laminated on the low moisture permeability hard coat layer. As the antireflection layer, a known layer can be preferably used. Among them, a UV curable antireflection layer is preferable.
The antireflection layer may be either a low-reflectance layer having a single-layer thickness λ / 4 or a multilayer structure, but a low-reflectance layer having a single-layer thickness λ / 4 is particularly preferable. The low refractive material that can be preferably used in the present invention will be described below, but the present invention is not limited thereto.

[Low refractive material for antireflection layer]
The low refractive material for the antireflection layer will be described below.

[Inorganic fine particles]
From the viewpoint of lowering the refractive index and improving scratch resistance, it is preferable to use inorganic fine particles in the antireflection layer. The inorganic fine particles are not particularly limited as long as the average particle size is 5 to 120 nm, but inorganic low refractive index particles are preferable from the viewpoint of lowering the refractive index.

  Examples of the inorganic fine particles include magnesium fluoride and silica fine particles because of their low refractive index. In particular, silica fine particles are preferable in terms of refractive index, dispersion stability, and cost. The size (primary particle size) of these inorganic particles is preferably 5 to 120 nm, more preferably 10 to 100 nm, 20 to 100 nm, and most preferably 30 to 90 nm.

  If the particle size of the inorganic fine particles is too small, the effect of improving the scratch resistance is reduced. If the particle size is too large, fine irregularities are formed on the surface of the low refractive index layer, and the appearance such as black tightening and the integrated reflectance are deteriorated. Further, when hollow silica fine particles described later are used, if the particle size is too small, the ratio of the cavity portion is reduced and a sufficient decrease in the refractive index cannot be expected. The inorganic fine particles may be either crystalline or amorphous, and may be monodispersed particles or aggregated particles as long as a predetermined particle size is satisfied. The shape is most preferably spherical, but may be indefinite.

The coating amount of the inorganic fine particles is ^{preferably 1mg / m 2 ~100mg / m 2} , more preferably ^{5mg / m 2 ~80mg / m 2} , more preferably from ^{10mg / m 2 ~60mg / m 2} . If the amount is too small, a sufficiently low refractive index cannot be expected or the effect of improving the scratch resistance is reduced. If the amount is too large, fine irregularities are formed on the surface of the low refractive index layer, and the appearance and integration such as black tightening Reflectivity deteriorates.

(Porous or hollow fine particles)
In order to reduce the refractive index, it is preferable to use fine particles having a porous or hollow structure. In particular, it is preferable to use hollow silica particles. The porosity of these particles is preferably 10 to 80%, more preferably 20 to 60%, and most preferably 30 to 60%. It is preferable that the void ratio of the hollow fine particles be in the above range from the viewpoint of lowering the refractive index and maintaining the durability of the particles.

  In the case of porous or hollow silica particles, the refractive index of the fine particles is preferably 1.10 to 1.40, more preferably 1.15 to 1.35, and most preferably 1.15 to 1.30. . The refractive index here represents the refractive index of the entire particle, and does not represent the refractive index of only the outer shell silica forming the silica particles.

  Moreover, two or more types of hollow silica particles having different particle average particle sizes can be used in combination. Here, the average particle diameter of the hollow silica can be determined from an electron micrograph.

The specific surface area of the hollow silica particles in the present invention is preferably from 20 to 300 m ² / g, more preferably 30~120m ² / g, most preferably 40~90m ² / g. The surface area can be determined by the BET method using nitrogen.

  In the present invention, silica particles having no voids can be used in combination with hollow silica particles. The preferred particle size of silica without voids is 30 nm to 150 nm, more preferably 35 nm to 100 nm, and most preferably 40 nm to 80 nm.

[Inorganic fine particle surface treatment method]
Further, in the present invention, inorganic fine particles can be used after being surface-treated with a silane coupling agent or the like by a conventional method.
In particular, in order to improve the dispersibility in the binder for forming the antireflection layer, the surface of the inorganic fine particles is preferably treated with a hydrolyzate of an organosilane compound and / or a partial condensate thereof. Further, it is more preferable to use either an acid catalyst or a metal chelate compound or both. The method for treating the surface of the inorganic fine particles is described in paragraphs [0046] to [0076] of JP-A-2008-242314, and the organosilane compound, the siloxane compound, and the solvent for the surface treatment described in this document. Surface treatment catalysts, metal chelate compounds, and the like can also be suitably used in the present invention.

For the antireflection layer, (b2) a fluorine-containing or non-fluorine-containing monomer having a polymerizable unsaturated group can be used. For the non-fluorinated monomer, it is also preferable to use a compound having an ethylenically unsaturated double bond group described as being usable in the hard coat layer. As the fluorine-containing monomer, a fluorine-containing polyfunctional monomer (d) represented by the following general formula (10), containing 35% by mass or more of fluorine and having a calculated value of all cross-linking molecular weights smaller than 500 is used. Is preferred.
Formula ^{_{(10): Rf 2 {-}} (L 10) S -Y 10} t
(In general formula (10), Rf ₂ represents a t-valent group containing at least a carbon atom and a fluorine atom, t represents an integer of 3 or more, L ¹⁰ represents a single bond or a divalent linking group, and s Represents 0 or 1. Y ¹⁰ represents a polymerizable unsaturated group.)
Rf ₂ may contain at least one of an oxygen atom and a hydrogen atom. Further, Rf ₂ is a chain (straight or branched) or cyclic.

Y ¹⁰ is preferably a group containing two carbon atoms that form an unsaturated bond, more preferably a radical polymerizable group, a (meth) acryloyl group, an allyl group, an α-fluoroacryloyl group, And those selected from —C (O) OCH═CH ₂ are particularly preferred. Among these, from the viewpoint of polymerizability, (meth) acryloyl group, allyl group, α-fluoroacryloyl group, and C (O) OCH═CH ₂ having radical polymerizability are more preferable.

L ¹⁰ represents a divalent linking group, and more specifically, an alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 10 carbon atoms, —O—, —S—, —N (R) —, 1 carbon atom. Group obtained by combining -O-, -S- or N (R)-with an alkylene group of 10 to 10 and a combination of -O-, -S- or N (R)-with an arylene group having 6 to 10 carbon atoms Represents a group obtained by R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. When L represents an alkylene group or an arylene group, the alkylene group and the arylene group represented by L are preferably substituted with a halogen atom, and preferably substituted with a fluorine atom.

(Moisture permeability of polarizing plate protective film)
The moisture permeability of the polarizing plate protective film of the present invention is preferably 50 to 250 g / m ² / day.
Here, the moisture permeability is a value after 24 hours at 40 ° C. and a relative humidity of 90% by the method of JIS Z-0208.
The moisture permeability of the polarizing plate protective film of the present invention is more preferably 230 g / m ² / day or less, still more preferably 200 g / m ² / day or less, and 170 g / m ² / day or less. Is particularly preferred.

<Layer structure of polarizing plate protective film>
The polarizing plate protective film of the present invention has a low moisture permeability hard coat layer formed on a support. Another layer may be interposed between the support and the low moisture-permeable hard coat layer.
Although the example of the preferable layer structure of the polarizing plate protective film of this invention is shown below, it is not necessarily limited only to these layer structures especially.

Support / Low moisture permeability hard coat layerSupport / Low moisture permeability hard coat layer / Antireflection layerSupport / Adhesion layer / Low moisture permeability hard coat layerSupport / Adhesion layer / Low moisture permeability hard coat layer / Antireflection layer / support / UV absorbing layer / low moisture permeability hard coat layer / Support / UV absorbing layer / low moisture permeability hard coat layer / Antireflection layer / support / adhesion layer / UV absorbing layer / low moisture permeability Hard coat layer / support / adhesion layer / ultraviolet absorption layer / low moisture permeability hard coat layer / antireflection layer / support / low moisture permeability hard coat layer / antiglare layer / support / low moisture permeability hard coat layer / anti-reflection Dazzle layer / Antireflection layer

[Thickness of low moisture-permeable hard coat layer]
The film thickness of the low moisture permeability hard coat layer of the present invention is preferably 3 μm or more and 30 μm or less, more preferably 4 μm or more and 20 μm or less, and further preferably 5 μm or more and 15 μm or less. When the film thickness of the low moisture permeable hard coat layer is 3 μm or more, sufficient hard coat properties can be obtained, and the moisture permeability can be lowered. By making the film thickness 30 μm or less, it is applied to the support. -Drying is easy in the drying step, and excellent brittleness can be obtained.
In addition, the film thickness of a low moisture-permeable hard-coat layer can be calculated | required from the thickness by measuring the film thickness before and behind lamination | stacking of a low moisture-permeable hard-coat layer.

[Mixed layer of cellulose ester support and low moisture permeability hard coat layer]
The polarizing plate protective film of the present invention preferably has a mixed layer in which the cellulose ester support and the low moisture permeability hard coat layer are mixed between the cellulose ester support and the low moisture permeability hard coat layer. This mixed layer is a layer in which the cellulose ester of the cellulose ester support and the polymer of the component (A) in the low moisture permeability hard coat layer are mixed.
By having the mixed layer, the adhesion between the cellulose ester support and the low moisture permeability hard coat layer is improved.
Presence / absence of the mixed layer can be confirmed by electron microscope observation of the cross section of the cellulose ester support provided with the low moisture permeability hard coat layer, for example, by observing using S-5200 (manufactured by Hitachi, Ltd.).
The thickness of the mixed layer is preferably 0.1 μm or more and 3 μm or less.
The thickness of the mixed layer can be measured by observing the cross section of the polarizing plate protective film with an electron microscope and measuring the length.

[Optically anisotropic layer]
The polarizing plate protective film of the present invention may further have an optically anisotropic layer. The optically anisotropic layer may be an optically anisotropic layer in which a film having a constant retardation is uniformly formed in the plane, and the direction of the slow axis and the magnitude of the retardation are different from each other. It may be an optically anisotropic layer having a pattern in which retardation regions are regularly arranged in a plane.
In the present invention, the optically anisotropic layer is preferably formed on the other surface of the above-mentioned support on which the above-mentioned low moisture-permeable hard coat layer is formed.
On the other hand, when the low moisture-permeable hard coat layer is laminated on the same side as the optically anisotropic layer with respect to the support, the low moisture-permeable hardcoat layer is laminated between the support and the optically anisotropic layer. Alternatively, the support, the optically anisotropic layer, and the low moisture permeability hard coat layer may be laminated in this order.

  A preferred example having an optically anisotropic layer formed uniformly in the plane is an embodiment in which the optically anisotropic layer is a λ / 4 film, and is particularly useful as a member of an active 3D liquid crystal display device. The optically anisotropic layer of λ / 4 film and the hard coat layer are described in JP 2012-098721 A and JP 2012-127882 A as a mode in which they are laminated on the opposite surface via a support, Such an embodiment can be preferably used in the polarizing plate protective film of the present invention.

On the other hand, a preferred example of the optically anisotropic layer on which a pattern is formed is a pattern type λ / 4 film, and the embodiments described in Japanese Patent Nos. 4825934 and 4887463 are applied to protect the polarizing plate of the present invention. It can be preferably used in a film.
Moreover, the aspect which combined the photo-alignment film and pattern exposure which were described in the Japanese translations of PCT publication No. 2012-517024 gazette (WO2010 / 090429 gazette) can also be preferably used with the polarizing plate protective film of this invention.

[Production method of polarizing plate protective film]
The polarizing plate protective film of the present invention can be produced by applying a composition for low moisture permeability hard coat layer on a cellulose ester support, drying it, and then irradiating with ultraviolet rays to cure the applied layer. it can. In the case of a protective film having another functional layer, the functional layer can be formed by a general method. In the step of irradiating ultraviolet rays, the effect is obtained by heating the cellulose ester support at a temperature of 10 ° C. to 90 ° C. with the illuminance of the ultraviolet rays being 10 to 5000 mW / cm ² and the irradiation amount being 10 to 10000 mJ / cm ^2. In particular, the reaction of the epoxy monomer can proceed. On the other hand, if desired performance can be obtained after ultraviolet irradiation, it is preferable not to heat after ultraviolet irradiation in order to prevent damage to the support or other layers.

[Polarizer]
The polarizing plate of this invention contains a polarizer and the polarizing plate protective film of this invention provided as a protective film in the at least one surface of this polarizer.
Further, the polarizing plate of the present invention comprises a polarizer, a polarizing plate protective film of the present invention provided as a protective film on one surface of the polarizer, and an optical anisotropic provided on the other surface of the polarizer. It may contain a functional film. The optically anisotropic film in this case can be the same as the optically anisotropic layer.
In the present invention, a method for manufacturing the polarizing plate is not particularly limited, and the polarizing plate can be manufactured by a general method. There is a method in which the obtained polarizing plate protective film is subjected to alkali treatment, and a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution is bonded to both surfaces using a completely saponified polyvinyl alcohol aqueous solution. Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed. Moreover, you may perform the above surface treatments. The bonding surface of the polarizing plate protective film with the polarizer may be a surface on which a low moisture permeability hard coat layer is laminated, or may be a surface on which a low moisture permeability hard coat layer is not laminated.

Examples of the adhesive used to bond the protective film treated surface and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like.
The polarizing plate is composed of a polarizer and a protective film for protecting both surfaces of the polarizer. Further, the polarizing plate is composed of a protective film on one surface and a separate film on the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the contact bonding layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate.

[Image display device]
The image display device of the present invention includes a liquid crystal cell and the polarizing plate of the present invention disposed in at least one of the liquid crystal cells, and the polarizing plate protective film of the present invention contained in the polarizing plate is on the image display surface. It is arranged. Examples of the image display device include a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), and a cathode ray tube display device (CRT). It is preferable to use it for an apparatus.

{General liquid crystal display device configuration}
The liquid crystal display device includes a liquid crystal cell having a liquid crystal supported between two electrode substrates, two polarizing plates disposed on both sides of the liquid crystal cell, and, if necessary, at least between the liquid crystal cell and the polarizing plate. It has a configuration in which one optical compensation film is arranged.
The liquid crystal layer of the liquid crystal cell is usually formed by sealing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on the substrate as a transparent film containing a conductive substance. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer, or an undercoat layer (undercoat layer) (used for adhesion of the transparent electrode layer). These layers are usually provided on the substrate. The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.

In a liquid crystal display device, a substrate including a liquid crystal cell is usually disposed between two polarizing plates, but the protective film for polarizing plates of the present invention can be used as any protective film of two polarizing plates. However, it is preferable that it is used as a protective film arrange | positioned on the outer side of a liquid crystal cell with respect to a polarizer among two protective films of each polarizing plate.
Of the two polarizing plates, it is particularly preferable to dispose the polarizing plate protective film of the present invention as the visual protective film of the visual side polarizing plate.
Moreover, after arranging the polarizing plate protective film of the present invention as the protective film on the viewing side of the viewing side polarizing plate of the two polarizing plates, the present invention is also applied to the backlight side protective film of the backlight side polarizing plate. It is also a preferable aspect to dispose the polarizing plate protective film of the invention, suppress the expansion and contraction of the polarizer contained in the two polarizing plates, and prevent the panel from warping.

{Types of liquid crystal display devices}
The polarizing plate protective film of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroly Liquid Liquid Crystal), OCB (Optically Liquid BTS). Various display modes such as ECB (Electrically Controlled Birefringence) and HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed. The polarizing plate protective film of the present invention is effective in any display mode liquid crystal display device. Further, it is effective in any of a transmissive type, a reflective type, and a transflective liquid crystal display device.

  In order to describe the present invention in detail, examples will be described below, but the present invention is not limited to these examples.

[Example 1]
(Preparation of coating composition for forming a low moisture permeability hard coat layer)
Each component was mixed with the following composition, and it filtered with the polypropylene filter with the hole diameter of 5 micrometers, and prepared the coating composition for low moisture-permeable hard-coat layer formation.

<Preparation of coating composition for forming a low moisture-permeable hard coat layer>
Compound 1a 49.3 parts by mass Irgacure 290 (BASF) 2.0 parts by mass Fluoroaliphatic group-containing copolymer (a)
(Solid content concentration 1 mass% MEK diluent) 2.0 mass parts MEK (methyl ethyl ketone) 14.6 mass parts MiBK (methyl isobutyl ketone) 34.0 mass parts

<Coating for forming a low moisture-permeable hard coat layer>
As a support, Fujitac TD60 (manufactured by FUJIFILM Corporation, width 1340 mm, thickness 60 μm) is unwound from the roll form, and the coating composition for forming a low moisture permeability hard coat layer is used. In the die coating method using the slot die described in Gazette Example 1, coating is performed under the condition of a conveyance speed of 30 m / min, and the temperature of the support is adjusted to 60 ° C. and dried for 150 seconds by adjusting the temperature in the coating equipment. It was. The temperature was measured with PT-2LD manufactured by OPTEX. Thereafter, using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with an oxygen concentration of about 0.1% by volume under a nitrogen purge and a temperature of the support of 25 ° C. and 160 W / cm, an illuminance of 400 mW / cm ² , A coating layer is cured by irradiating an ultraviolet ray with an irradiation amount of 300 mJ / cm ² , wound up, and then post-heated at 110 ° C. for 3 hours, and the obtained polarizing plate protective film having a low moisture permeability hard coat layer is sampled 1 (Example 1). The coating amount was adjusted so that the film thickness of the low moisture permeability hard coat layer was 10 μm.

[Examples 2 to 16, Comparative Examples 1 to 10]
Next, as shown in Table 1 and Table 2 below, a coating composition for forming a low moisture permeability hard coat layer in which the type and amount of the polyfunctional epoxy monomer and additive were changed was prepared. Furthermore, by applying the obtained coating composition for forming a low moisture permeability hard coat layer so as to have a film thickness described in Table 1 and Table 2 below, polarizing plate protective film samples 2 to 16 (Example 2) -16) and comparative polarizing plate protective film samples 1 to 10 (Comparative Examples 1 to 10) were obtained. In Example 12, ultraviolet rays were irradiated at a temperature of 60 ° C. Moreover, the Example films 15 and 16 were not post-heated.
Content of the polymeric compound of Table 1 and Table 2 is a ratio (mass%) in the total solid of the composition for low moisture-permeable hard-coat layers.

The materials used are shown below.
Compound 1a: TTA-22: Vinylcyclohexane dioxide (manufactured by Sigma Aldrich)
Compound 1b: TTA-20: 1-methyl-4- (2-methyloxiranyl) -7-oxabicyclo [4.1.0] heptane (manufactured by Wako Pure Chemical Industries, Ltd.)
Compound 1c: TTA27 (manufactured by Tetrachem)
Compound 1d: TTA184 (manufactured by Tetrachem)
Compound 2a: CEL8000 (manufactured by Daicel Corporation)
Compound 2b: synthesized according to literature (Progress in Organic Coatings, 58, 227 (2007)) Compound 2c: CEL2021P (manufactured by Daicel Corporation)
Compound 3a: Neopentyl glycol diglycidyl ether (Tokyo Kasei)
Compound 3b: trimethylolpropane triglycidyl ether (manufactured by Sigma Aldrich)
Compound 3c: EP-4088S (manufactured by ADEKA)
Compound 3d: TTA184 (manufactured by Tetrachem)
Compound 3e: TTA-2081 (manufactured by Tetrachem)
DPHA: Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.)
Silica: MEK-EC-2130Y (manufactured by Nissan Chemical Industries, Ltd.)

[Evaluation of polarizing plate protective film]
The film thickness was measured about the produced polarizing plate protective film of each Example and the comparative example, and the following physical-property measurement and evaluation were performed. The results are shown in Tables 1 and 2. The film thickness of the low moisture permeability hard coat layer was determined from the difference between the thicknesses measured before and after the lamination of the low moisture permeability hard coat layer. The layer thickness of the mixed layer was determined by cross-sectional SEM (S-5200, manufactured by Hitachi, Ltd.) observation.

Moisture permeability (moisture permeability at 40 ° C 90% relative humidity)
70 mmφ of polarizing plate protective film samples of each Example and Comparative Example were conditioned for 24 hours at 40 ° C. and 90% relative humidity, and measured by the method described in JIS Z-0208.
The moisture permeability of the low moisture permeability hard coat layer is determined by measuring the moisture permeability of each polarizing plate protective film and the cellulose ester support, and from the moisture permeability of the cellulose ester support and the moisture permeability of the polarizing plate protective film, the following formula (1 ).

(Moisture permeability of low moisture permeable layer)
From the gas transmission type of the composite film (e.g., "barrier of Science of the packaging material (packaging Fundamental Course 5)" p68~72 Tsutomu Nakagawa al Japan Packaging Institute), the moisture permeability of the polarizing plate protective film of the steady state J _f When the moisture permeability of the cellulose ester support is J _s , and the moisture permeability of the low moisture permeability hard coat layer when the polarizing plate protective film is separated into the cellulose ester support and the low moisture permeability hard coat layer is J _b , The following equation holds.
1 / J _f = 1 / J _S + 1 / J _b Equation (1)
The moisture permeability J _f of the polarizing plate protective film and the moisture permeability J _S of the cellulose ester support can be directly measured, and the moisture permeability J _b of the low moisture permeable layer can be calculated based on the measured values. it can.

Adhesion evaluation The surface of the polarizing plate protective film on the side having the low moisture permeability hard coat layer is cut into 11 vertical and 11 horizontal cuts with a cutter knife to make a total of 100 1 mm × 1 mm sizes. Nitto Denko Co., Ltd. polyester adhesive tape “NO.31B” was pressure-bonded to perform an adhesion test between the support and the coating layer, and the presence or absence of peeling was visually observed.
When peeling was less than 20% in 100 squares, an adhesion test was performed at the same place, and a repeated test was performed at most twice. The presence or absence of peeling was visually observed, and the following five-step evaluation was performed.
A: No peeling was observed in 100 squares in 2 adhesion tests B: 1 to 3 square peeling in 100 squares in 2 adhesion tests C: 100 in 2 adhesion tests D: 4 to 10 mm peel in one cell D: More than 10 cells peeled in 100 cells in 2 adhesion tests E: 10 cells peeled in 100 cells in 1 adhesion test Things beyond the fence

Pencil hardness evaluation Pencil hardness evaluation described in JIS K 5400 was performed as an index of scratch resistance. After conditioning the polarizing plate protective film at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, using a 2B to 3H test pencil specified in JIS S 6006 at a load of 4.9 N, as follows: Evaluation was made based on the judgment, and the highest hardness that gave OK was taken as the evaluation value.
OK: No more than 4 scratches in the evaluation of n = 5 NG: No more than 3 scratches in the evaluation of n = 5

Brittleness evaluation The brittleness was evaluated by the paint general test method described in JIS-K-5600-5-1-bending resistance (cylindrical mandrel method). That is, after storing for 16 hours under the conditions of a temperature of 25 ° C. and a humidity of 55% RH, each sample was wound around a mandrel having a diameter (Φ) of 2, 3, 4, 5, 6, 8, 10, 12 mm, and cracked. The occurrence of cracks was observed, and crack resistance was evaluated with the smallest mandrel diameter at which no cracks occurred. It shows that the crack resistance is so weak that the crack has generate | occur | produced on the conditions where the diameter of a mandrel is large.

Coloring Evaluation Absorption spectra (spectrophotometer UV-3150, manufactured by Shimadzu Corporation) of the cellulose ester support and the polarizing plate protective film were measured, and the chromaticity (L * a * b *) with a C light source was determined.
It evaluated by the following determination from (DELTA) b * (difference of b * value of a cellulose-ester support body and a polarizing plate protective film).
A: Δb * ≦ 0.2
B: Δb *> 0.2

[Evaluation of liquid crystal display devices]
Light Leakage Evaluation A liquid crystal display device was produced using each polarizing plate protective film produced by the method described above.

[Panel Evaluation]
<Preparation of polarizing plate>
1) Saponification of film Commercially available cellulose acylate film (Fujitack ZRD40, manufactured by Fuji Film Co., Ltd.), commercially available cellulose acylate film TD60 (manufactured by Fuji Film Co., Ltd.), and the polarizing plate protective film sample 1 prepared above 16 and comparative polarizing plate protective film samples 1 to 10 were immersed in a 1.5 mol / L NaOH aqueous solution (saponification solution) maintained at 55 ° C. for 2 minutes, and then the film was washed with water. After being immersed in a 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, a water washing bath was passed under running water for 30 seconds to make the film neutral. Then, draining with an air knife was repeated three times, and after dropping the water, the film was retained in a drying zone at 70 ° C. for 15 seconds and dried to produce a saponified film.

2) Production of Polarizer According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, iodine was adsorbed to a stretched polyvinyl alcohol film to produce a polarizer having a thickness of 20 μm.

3) Bonding (preparation of front side polarizing plate: polarizing plates 1 to 16 and comparative polarizing plates 1 to 10)
Polarized plate protective film samples 1 to 16 and comparative polarizing plate protective film samples 1 to 10 after saponification (disposed so that the surface of the polarizing plate protective film on which the low moisture-permeable layer is not laminated is in contact with the polarizer) The polarizer prepared above and the cellulose acylate film ZRD40 after saponification were bonded together in this order with a PVA adhesive and thermally dried to obtain polarizing plates 1 to 16 and comparative polarizing plates 1 to 10. Was made.
Under the present circumstances, it arranged so that the longitudinal direction of the roll of the produced polarizer and the longitudinal direction of polarizing plate protective film samples 1-16 and comparative polarizing plate protective film samples 1-10 may become parallel. Moreover, it arrange | positioned so that the longitudinal direction of the roll of a polarizer and the longitudinal direction of the roll of the said cell roll acylate film ZRD40 may become parallel.

(Preparation of rear-side polarizing plate)
The saponified cellulose acylate film TD60, the stretched iodine-based PVA polarizer, and the saponified cellulose acylate film ZRD40 are bonded in this order with a PVA-based adhesive, and then thermally dried to form a rear-side polarizing plate. Obtained.
Under the present circumstances, it arrange | positioned so that the longitudinal direction of the roll of the produced polarizer and the longitudinal direction of the cell roll acylate film TD60 may become parallel. Moreover, it arrange | positioned so that the longitudinal direction of the roll of a polarizer and the longitudinal direction of the roll of the said cell roll acylate film ZRD40 may become parallel.

<Implementation to IPS panel>
The upper and lower polarizing plates of the IPS mode liquid crystal cell (LGS 42LS5600) are peeled off, and the polarizing plates 1 to 16 and the polarizing plates 1 to 10 for comparison described above as the front side polarizing plate are arranged on the rear side on the front side (viewing side). The polarizing plates described above as the rear-side polarizing plates were attached to the front side and the rear side one by one through an adhesive so that the cell roll acylate film ZRD40 was 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.
The obtained liquid crystal display devices were designated as liquid crystal display devices 1 to 16 (Examples 1 to 16) and comparative liquid crystal display devices 1 to 10 (Comparative Examples 1 to 10), respectively.

  The light leakage of the liquid crystal display device produced as described above was evaluated. The results are shown in Tables 1 and 2 below.

[Light leakage evaluation (panel evaluation)]
For the liquid crystal display devices 1 to 16 (Examples 1 to 16) and the comparative liquid crystal display devices 1 to 10 (Comparative Examples 1 to 10) thus produced, after thermostating at 60 ° C. and 90% relative humidity for 48 hours, 25 The backlight of the liquid crystal display device was turned on after being left at 60 ° C. and a relative humidity of 60% for 2 hours, and light leakage at the four corners of the panel was evaluated 5 hours and 10 hours after the lighting.
The light leakage evaluation was performed by photographing a black display screen from the front of the screen with a luminance measurement camera “ProMetric” (Radian Imaging), based on the average luminance of the entire screen and the luminance difference between the four corners where light leakage is large. Thus, it was evaluated on a 7-point scale. In the present invention, the levels of a and b are within the allowable range, and the levels of c to g are not allowable.
a: After 5 hours, light leakage from the four corners of the panel is not visually recognized.
After 10 hours, light leakage from the four corners of the panel is not visually recognized.
b: After 5 hours, slight light leakage is visually recognized at one or two of the four corners of the panel.
After 10 hours, light leakage from the four corners of the panel is not visually recognized.
c: After 5 hours, slight light leakage is visually recognized at one or two of the four corners of the panel.
After 10 hours, slight light leakage is visually recognized at one or two of the four corners of the panel.
d: After 5 hours, slight light leakage is visually recognized at 3 to 4 corners among the 4 corners of the panel.
After 10 hours, slight light leakage is visually recognized at one or two of the four corners of the panel.
e: After 5 hours, slight light leakage is visually recognized at 3 to 4 of the 4 corners of the panel.
After 10 hours, slight light leakage is visually recognized at 3 to 4 of the 4 corners of the panel.
f: After 5 hours, light leakage at the four corners of the panel is strong and unacceptable.
After 10 hours, slight light leakage is visually recognized at 3 to 4 of the 4 corners of the panel.
g: After 5 hours, strong light leakage is visually recognized at the four corners of the panel.
After 10 hours, strong light leakage is visible at the four corners of the panel.

As shown in Table 1 and Table 2 above, Examples 1 to 16, which are polarizing plate protective films of the present invention, have a low moisture permeability comprising a composition containing a predetermined amount of a predetermined polyfunctional epoxy monomer and a photocationic polymerization initiator. Since it has a hard coat layer, it was excellent in hardness, brittleness and adhesion, less colored, and low in moisture permeability. Moreover, the liquid crystal display device produced using the polarizing plate protective film of this invention had little light leakage.
On the other hand, in Comparative Examples 1 to 10, the monomer used does not have any of an epoxy ring and a cyclic skeleton other than the epoxy ring, the monomer has a molecular weight of over 270, or the content of the polyfunctional epoxy monomer. Since the content was less than 70% by mass, the evaluation result was poor.

Claims (13)

A polarizing plate protective film having a cellulose ester support and a low moisture permeability hard coat layer,
The low moisture-permeable hard coat layer is formed from a composition for low moisture-permeable hard coat layer containing the following (A) and (B):
Content of following (A) is a polarizing plate protective film which is 70 mass% or more with respect to the total solid in the said composition for low moisture-permeable hard-coat layers.
(A) Multifunctional epoxy monomer having two or more epoxy rings and one or more cyclic skeletons other than epoxy rings in one molecule and having a molecular weight of 270 or less (B) Photocationic polymerization initiator   The polarizing plate protective film according to claim 1, wherein the cyclic skeleton other than the epoxy ring is a cyclohexane ring. The polarizing plate protective film according to claim 1, wherein (A) is a compound represented by the following general formula (1).
General formula (1)

In the general formula (1), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom, a methyl group or an ethyl group.
X includes a single bond or an alkylene group that may have a substituent, an arylene group that may have a substituent, an aralkylene group that may have a substituent, an ester bond, an ether bond, or a heterocyclic ring. A (m + n) -valent linking group comprising a linking group or a combination thereof is represented.
m and n each independently represent an integer of 0 or more and 2 or less, and m + n ≧ 2.
When there are a plurality of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ , the plurality of R ₁ , the plurality of R ₂ , the plurality of R ₃ , the plurality of R ₄ and the plurality of R ₅ are the same or different. It may be. Said (A) is a compound represented by following General formula (2), The polarizing plate protective film as described in any one of Claims 1-3.
General formula (2)

In the general formula (2), R ₆ , R ₇ , R ₈ and R ₉ each independently represent a hydrogen atom, a methyl group or an ethyl group.
Y includes a single bond or an alkylene group that may have a substituent, an arylene group that may have a substituent, an aralkylene group that may have a substituent, an ester bond, an ether bond, and a heterocyclic ring. A divalent linking group comprising a linking group or a combination thereof is represented.   The polarizing plate protective film according to claim 1, wherein the low moisture-permeable hard coat layer composition further contains an inorganic filler.   The polarizing plate protective film according to claim 1, wherein a film thickness of the low moisture-permeable hard coat layer is 3 μm or more and 30 μm or less.   Between the cellulose ester support and the low moisture-permeable hard coat layer, there is a mixed layer in which the cellulose ester support and the low moisture-permeable hard coat layer are mixed, and the thickness of the mixed layer is 0.1 μm. The polarizing plate protective film according to any one of claims 1 to 6, which is 3 µm or less.   The polarizing plate containing a polarizer and the polarizing plate protective film as described in any one of Claims 1-7 provided as a protective film in the at least one surface of the said polarizer.   An image display device comprising: a liquid crystal cell; and the polarizing plate according to claim 8 disposed on at least one surface of the liquid crystal cell. A method for producing a polarizing plate protective film having a cellulose ester support and a low moisture permeability hard coat layer,
The low moisture-permeable hard coat layer is formed from a composition for low moisture-permeable hard coat layer containing the following (A) and (B):
Content of following (A) is a manufacturing method of the polarizing plate protective film which is 70 mass% or more with respect to the total solid in the said composition for low moisture-permeable hard-coat layers.
(A) Multifunctional epoxy monomer having two or more epoxy rings and one or more cyclic skeletons other than epoxy rings in one molecule and having a molecular weight of 270 or less (B) Photocationic polymerization initiator   The manufacturing method of the polarizing plate protective film of Claim 10 which produces the said low moisture-permeable hard-coat layer by irradiating an ultraviolet-ray after apply | coating the said composition for low moisture-permeable hard-coat layers on the said cellulose-ester support body. Method.   The polarizing plate protective film according to claim 11, wherein the low moisture-permeable hard coat layer is produced by irradiating ultraviolet rays in a heated state of the cellulose ester support coated with the low moisture-permeable hard coat layer composition. Manufacturing method.   The manufacturing method of the polarizing plate protective film of Claim 11 or 12 which produces the said low moisture-permeable hard-coat layer, without heating after irradiating the said ultraviolet-ray.