JP6826810B2 - Polarizer - Google Patents

Description

The present invention relates to a polarizing plate, and more particularly to a polarizing plate having a cured product layer composed of a cured product of a curable composition on one surface of a polarizing film containing a dichroic dye.

Conventionally, a polarizing plate has been used in various image display panels such as a liquid crystal display panel and an organic electroluminescence (organic EL) display panel by being bonded to an image display element such as a liquid crystal cell or an organic EL display element. As such a polarizing plate, a triacetyl cellulose film is provided on one or both surfaces of a polarizing film in which a bicolor dye such as iodine or a bicolor dye is adsorbed and oriented on a polyvinyl alcohol-based resin film via an adhesive layer. A polarizing plate having a structure in which a protective film such as the above is laminated is known (for example, Patent Document 1). Such a polarizing plate is in the form of further laminating various optical layers such as a retardation film and an optical compensation film as needed, and is an image display element such as a liquid crystal cell or an organic EL display element via an adhesive. It is attached to the image display panel.

Japanese Unexamined Patent Publication No. 2012-208250

When the image display panel is charged with static electricity, the display function becomes defective. Therefore, static electricity may be prevented by adding an antistatic agent to the polarizing plate. For example, an antistatic agent may be blended in the adhesive layer in the polarizing plate. In this case, the polarizing plate has optical performance such as polarization during long-term use and / or use in a high temperature and high humidity environment. It may decrease over time. It is considered that the cause of this is that the antistatic agent in the adhesive layer moves to the polarizing film over time and interacts with a dichroic dye such as iodine in the polarizing film, so that the polarizing property is lowered. With such a polarizing plate having deteriorated optical performance, the image display performance may be deteriorated.

Therefore, an object of the present invention is to solve the above-mentioned problems that may occur peculiar to a polarizing plate having an antistatic function, to suppress a decrease in optical performance with time, and to provide a polarizing plate having high durability. And.

The present invention provides the following preferred embodiments [1] to [4].
[1] On one surface of a polarizing film containing a bicolor dye in a polyvinyl alcohol-based resin, a first cured product layer composed of a cured product of a curable composition containing a polymerizable compound, and an ionic compound. A polarizing plate containing the pressure-sensitive adhesive layer containing the above-mentioned, in this order, the polymerizable compound.
It contains (A1) an oxetane compound having two or more oxetanyl groups, and (A2) an aliphatic epoxy compound having two or more epoxy groups.
The curable composition is based on 100% by mass of the total amount of the polymerizable compound.
(A1) 15 to 70% by mass, and (A2) 3 to 40% by mass
Contains,
A polarizing plate in which the content of the oxetane compound (A3) having one oxetanyl group is 10% by mass or less based on 100% by mass of the total amount of the polymerizable compound.
[2] A first transparent protective film is provided between the first cured product layer and the adhesive layer, and the first transparent protective film has an air atmosphere of 23 ° C. and 60% RH in a 50 mass% potassium iodide aqueous solution. The absorbance of light with a wavelength of 360 nm after the treatment of immersing underneath for 4.5 hours, taking it out, washing it with water at 23 ° C. in the air for 15 seconds, and drying it in a dark place at 23 ° C. in the air for 15 hours The polarizing plate according to the above [1], which is 5% or more higher than the absorbance of.
[3] The polarizing plate according to the above [1] or [2], wherein a second transparent protective film is provided on a surface of the polarizing film opposite to the first cured product layer side via a second cured product layer. ..

According to the present invention, it is possible to suppress a decrease in optical performance with time, and to provide a polarizing plate having high durability.

A cross-sectional view showing a structure which is one aspect of the structure of a polarizing plate is shown. A cross-sectional view showing a structure which is one aspect of the structure of a polarizing plate is shown.

The polarizing plate of the present invention has a first cured product layer composed of a cured product of a curable composition containing a polymerizable compound on one surface of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin. , The adhesive layer containing the ionic compound is contained in this order.

Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described here, and various modifications can be made without impairing the gist of the present invention.

The configuration of one embodiment of the polarizing plate of the present invention will be described with reference to FIG. The polarizing plate (10) of the present invention has a structure in which a first cured product layer (2) and an adhesive layer (3) are laminated in this order on one surface of a polarizing film (1). If necessary, a second transparent protective film (5) may be provided on the surface of the polarizing film (1) opposite to the first cured product layer side via the second cured product layer (4). ..

The polarizing plate (10) of the present invention has a structure in which the first cured product layer (2) and the adhesive layer (3) are laminated in this order on one surface of the polarizing film (1), and further, the first The first transparent protective film (6) may be provided between the cured product layer (2) and the adhesive layer (3). This embodiment is shown in FIG. The polarizing plate (10) is provided with a second transparent protective film (5) via a second cured product layer (4) on a surface of the polarizing film (1) opposite to the first cured product layer, if necessary. ) May be provided.

The polarizing plate (10) of the present invention is placed on one surface of the liquid crystal cell (X) via an adhesive layer, and the same or different polarizing plate as the polarizing plate of the present invention is further placed on the other surface of the liquid crystal cell. A liquid crystal display panel is configured by arranging in.
Hereinafter, each component of the polarizing plate of the present invention will be described in detail.

[First cured product layer]
The polarizing plate of the present invention contains a first cured product layer on one surface of a polarizing film. The first cured product layer is composed of a cured product of a curable composition containing a polymerizable compound, and the curable composition is:
It contains (A1) an oxetane compound having two or more oxetanyl groups, and (A2) an aliphatic epoxy compound having two or more epoxy groups.

(A1) An oxetane compound having two or more oxetane groups (hereinafter, may be referred to as "oxetane compound (A1)") is a compound having two or more oxetane groups (oxetane rings) in the molecule. The oxetane compound (A1) may be aliphatic, alicyclic or aromatic. Examples of the oxetane compound (A1) include 1,4-bis [{(3-ethyloxetane-3-yl) methoxy} methyl] benzene (also referred to as xylylene bisoxetane) and bis (3-ethyl-3-3). Oxetanetylmethyl) ether and the like can be mentioned. These oxetane compounds (A1) may be used alone or in combination of a plurality of different types. By containing the oxetane compound (A1) having two or more oxetanyl groups as the polymerizable compound, the curable composition can be cured to obtain a dense cured product having a high crosslink density. Therefore, by providing the cured product layer composed of such a cured product between the polarizing film and the adhesive layer, it is possible to effectively suppress the movement of the ionic compound from the adhesive layer.

An aliphatic epoxy compound (A2) having two or more epoxy groups (hereinafter, may be referred to as “aliphatic epoxy compound (A2)”) has at least two epoxy rings bonded to an aliphatic carbon atom in the molecule. It is a compound having one or more. Examples of the aliphatic epoxy compound (A2) include bifunctional epoxy compounds such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; trimethyl propantri. Trifunctional or higher functional epoxy compounds such as glycidyl ether and pentaerythritol tetraglycidyl ether; one epoxy group directly bonded to the alicyclic ring such as 4-vinylcyclohexendioxide and limonendioxide, and an aliphatic carbon atom There are epoxy compounds having an oxylane ring and the like. The aliphatic epoxy compound (A2) may be used alone or in combination of a plurality of different types.

Of these, a bifunctional epoxy compound (also referred to as an aliphatic diepoxy compound) having two oxylan rings bonded to an aliphatic carbon atom in the molecule is preferable from the viewpoint of adhesion between the polarizing film and the transparent protective film. An aliphatic diepoxy compound represented by the following formula (I) is more preferable. In particular, when the curable composition contains an aliphatic diepoxy compound represented by the following formula (I), a curable composition having a low viscosity and easy to apply can be obtained.

式（Ｉ）中、Ｚは炭素数１〜９のアルキレン基、炭素数３もしくは４のアルキリデン基、２価の脂環式炭化水素基、または式−Ｃ_mＨ_2m−Ｚ¹−Ｃ_nＨ_2n−で示される２価の基である。また、前記式−Ｃ_ｍＨ_２ｍ−Ｚ^１−Ｃ_ｎＨ_２ｎ−中、−Ｚ¹−は、−Ｏ−、−ＣＯ−Ｏ−、−Ｏ−ＣＯ−、−ＳＯ₂−、−ＳＯ−、または−ＣＯ−を表し、ｍおよびｎは各々独立に１以上の整数を表すが、両者の合計は９以下である。
２価の脂環式炭化水素基は、例えば、炭素数４〜８の２価の脂環式炭化水素基であってよく、式（Ｉ−１）で表される２価の基等が挙げられる。

In formula (I), Z is an alkylene group having 1 to 9 carbon atoms, an alkylidene group having 3 or 4 carbon atoms, a divalent alicyclic hydrocarbon group, or a formula −C _m H _{2 m} −Z ¹ −C _n H. It is a divalent group represented by _2n −. Further, in the above formula −C _m H _2m −Z ¹ −C _n H _2n −, −Z ¹ − is −O−, −CO−O−, −O−CO−, −SO ₂₋ , −SO−. , Or −CO−, where m and n each independently represent an integer of 1 or more, but the sum of both is 9 or less.
The divalent alicyclic hydrocarbon group may be, for example, a divalent alicyclic hydrocarbon group having 4 to 8 carbon atoms, and examples thereof include a divalent group represented by the formula (I-1). Be done.

Specifically, the aliphatic diepoxy compound represented by the above formula (I) is a diglycidyl ether of an alkanediol, a diglycidyl ether of an oligoalkylene glycol up to about 4 repetitions, or a diglycidyl ether of an alicyclic diol. Is.

Examples of the diol (glycol) capable of forming the aliphatic diepoxy compound represented by the above formula (I) include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, and 2-. Butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3 -Methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3, Alcan diols such as 5-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol and 1,9-nonanediol;
Oligoalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol and dipropylene glycol;
Examples thereof include alicyclic diols such as cyclohexanediol and cyclohexanedimethanol.

In the present invention, as the aliphatic diepoxy compound represented by the above formula (I), 1,4-butanediol diglycidyl ether, 1,6--butanediol diglycidyl ether, from the viewpoint of obtaining a curable composition having low viscosity and easy to apply. Hexanediol diglycidyl ether and neopentyl glycol diglycidyl ether are preferable. 1,6-Hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, and pentaerythritol polyglycidyl ether are preferable because the optical performance can be maintained. The aliphatic diepoxy compounds may be used alone or in combination of a plurality of different types.

In the present invention, the curable composition is an oxetane compound (A1) in an amount of 15 to 70% by mass, preferably 35 to 60% by mass, more preferably 45 to 55% by mass, based on 100% by mass of the total amount of the polymerizable compound. )including. When the content of the oxetane compound (A1) in the curable composition is at least the above lower limit value, the movement of the ionic compound can be sufficiently suppressed. When the content of the oxetane compound (A1) in the curable composition is not more than the above upper limit value, curing proceeds rapidly, and a cured product layer having sufficient hardness can be easily formed.

When the curable composition contains an aliphatic epoxy compound (A2), the curable composition is 3 to 40% by mass, preferably 5 to 25% by mass, based on 100% by mass of the total amount of the polymerizable compound. , More preferably 5 to 15% by mass of the aliphatic epoxy compound (A2). When the content of the aliphatic epoxy compound (A2) in the curable composition is at least the above lower limit value, a composition having low viscosity and easy to apply can be obtained. When the content of the aliphatic epoxy compound (A2) in the curable composition is not more than the above upper limit value, the elasticity of the cured product after curing does not become too low, and cracking due to heat shrinkage of the polarizing film can be suppressed. ..

The curable composition may contain an oxetane compound (A3) having one oxetanyl group. The content of the oxetane compound (A3) having one oxetanyl group is 10% by mass or less, preferably 5% by mass or less, even if it is 0% by mass, based on 100% by mass of the total amount of the polymerizable compound. Good. When the content of the oxetane compound (A3) having one oxetanyl group is not more than the above upper limit value, the crosslink density is high and a dense cured product can be easily obtained.

The curable composition may contain a compound (A4) having two or more epoxy groups other than the aliphatic epoxy compound (A2). Examples of the compound (A4) having two or more epoxy groups include an alicyclic epoxy compound (A4-1) having two or more epoxy groups (hereinafter, “alicyclic epoxy compound (A4-1)”). (May be referred to), and an aromatic epoxy compound (A4-2) having two or more epoxy groups (hereinafter, may be referred to as “aromatic epoxy compound (A4-2)”).

で示される構造における橋かけの酸素原子−Ｏ−を意味する。上記式（ａ）中、ｍは２〜５の整数である。 The alicyclic epoxy compound (A4-1) is a compound having two or more epoxy groups bonded to the alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" is the following formula (a):

It means the bridging oxygen atom -O- in the structure represented by. In the above formula (a), m is an integer of 2 to 5.

The compound in which one or more hydrogen atoms in (CH ₂ ) _m in the above formula (a) are removed and two or more groups are bonded to another chemical structure is an alicyclic epoxy compound (A4). -1) can be. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. The alicyclic epoxy compound (A4-1) may be used alone or in combination of a plurality of different types.

Among them, from the viewpoint of high glass transition temperature of the cured product and excellent adhesion between the polarizing film and the transparent protective film, an epoxy cyclopentane structure [m = 3 in the above formula (a)] and epoxy cyclohexane An alicyclic epoxy compound having a structure [m = 4 in the above formula (a)] is preferable, and an alicyclic die epoxy compound represented by the following formula (II) is more preferable. In particular, when the curable composition contains an aliphatic diepoxy compound represented by the following formula (II), the cured product layer after the curable composition is cured has high elasticity and heat shrinkage of the polarizing film. It is possible to suppress cracking due to.

式（ＩＩ）中、Ｒ¹およびＲ²は各々独立に水素原子または炭素数１〜６のアルキル基を表すが、アルキル基が炭素数３以上の場合は脂環構造を有していてもよい。前記炭素数１〜６のアルキル基は直鎖または分枝アルキル基であってよく、脂環構造を有するアルキル基としては、シクロプロピル基、シクロブチル基、シクロペンチル基等が挙げられる。

In formula (II), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, but when the alkyl group has 3 or more carbon atoms, it may have an alicyclic structure. .. The alkyl group having 1 to 6 carbon atoms may be a linear or branched alkyl group, and examples of the alkyl group having an alicyclic structure include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group and the like.

のいずれかで示される２価の基である。
炭素数１〜６のアルカンジイル基としては、例えば、メチレン基、エチレン基、プロパン−１，２−ジイル基等が挙げられる。 In formula (II), X is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (IIa) to (IId):

It is a divalent group represented by any of.
Examples of the alkanediyl group having 1 to 6 carbon atoms include a methylene group, an ethylene group, a propane-1,2-diyl group and the like.

X in formula (II), when a divalent group represented by any of the above formulas (IIa) ~ (IId), the ^Y 1 to Y ⁴ carbon atoms each independently from 1 to 20 in each formula It is an alkanediyl group, and when the alkanediyl group has 3 or more carbon atoms, it may have an alicyclic structure.

Examples of the alicyclic diepoxy compound include the following compounds A to M. The chemical formulas A to M shown thereafter correspond to the compounds A to M, respectively.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,
C: Ethylene bis (3,4-epoxycyclohexanecarboxylate),
D: Bis (3,4-epoxycyclohexylmethyl) adipate,
E: Bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,
F: Diethylene glycol bis (3,4-epoxycyclohexylmethyl ether),
G: Ethylene glycol bis (3,4-epoxycyclohexylmethyl ether),
H: 2,3,14,15-Diepoxy-7,11,18,21-Tetraoxatrispyro [5.2.2.5.2.2] Heneicosane,
I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy-1,5-dioxaspiro [5.5] undecane,
J: 4-Vinylcyclohexene dioxide,
K: Limonene Geoxide,
L: Bis (2,3-epoxycyclopentyl) ether,
M: Dicyclopentadiene dioxyside.

In the present invention, as the alicyclic diepoxy compound, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate is preferable from the viewpoint of industrial availability and the like. The alicyclic diepoxy compounds may be used alone or in combination of a plurality of different types.

Aromatic epoxy compound (A4-2) is a compound having two or more epoxy groups and one or more aromatic rings. Examples of the aromatic epoxy compound (A4-2) include the following.
For example, bisphenol A, bisphenol F, or glycidyl etherified compounds or epoxy novolac resins obtained by further adding an alkylene oxide to these;
Glycidyl ether, an aromatic compound having two or more phenolic hydroxyl groups such as resorcinol, hydroquinone, and catechol;
A glycidyl etherified product of an aromatic compound having two or more alcoholic hydroxyl groups such as benzenedimethanol, benzenediethanol, and benzenedibutanol;
Glycidyl ester of a polybasic acid aromatic compound having two or more carboxylic acids such as phthalic acid, terephthalic acid, trimellitic acid;
Glycidyl esters of benzoic acids such as benzoic acid, toluic acid, and naphthoic acid;
Epoxy of styrene oxide or divinylbenzene, etc.
The aromatic epoxy compound (A4-2) may be used alone or in combination of a plurality of different types.

Among them, from the viewpoint of lowering the viscosity of the curable composition, glycidyl etherified product of an aromatic compound having two or more alcoholic hydroxyl groups, glycidyl etherified product of polyhydric phenols, glycidyl ester of benzoic acids, and glycidyl of polybasic acids It preferably contains at least one selected from the group of esters, styrene oxides or epoxidized divinylbenzenes.

Further, since the curability of the curable composition is improved, the aromatic epoxy compound (A4-2) preferably has an epoxy equivalent of 80 to 500. The aromatic epoxy compound (A4-2) may be used alone or in combination of a plurality of different types.

In a preferred embodiment of the present invention, the curable resin composition comprises an aliphatic diepoxy compound represented by the above formula (I) and an alicyclic diepoxy compound represented by the above formula (II). In this case, a dense cured product layer having a high crosslink density can be obtained, and the movement of the ionic compound from the adhesive layer can be effectively suppressed. Further, when the curable composition contains an aromatic epoxy compound (A4-2), a hydrophobic cured product layer can be formed, and the movement of the ionic compound can be further suppressed.

When the curable composition contains an alicyclic epoxy compound (A4-1), the curable composition is preferably 10 to 70% by mass, more preferably 10% by mass, based on 100% by mass of the total amount of the polymerizable compound. Contains 25-60% by mass, more preferably 25-50% by mass of an alicyclic epoxy compound (A4-1). When the content of the alicyclic epoxy compound (A4-1) in the curable composition is within the above range, curing by irradiation with active energy rays proceeds rapidly, and a cured product layer having sufficient hardness is easily formed. can do.

When the curable composition contains an aromatic epoxy compound (A4-2), the curable composition is preferably 0.1 to 20% by mass, based on 100% by mass of the total amount of the polymerizable compound. It preferably contains 5 to 20% by weight of an aromatic epoxy compound (A4-2). When the content of the aromatic epoxy compound (A4-2) in the curable composition is at least the above lower limit value, the cured product tends to be hydrophobic, and the permeation of the ionic compound can be further suppressed. When the content of the aromatic epoxy compound (A4-2) in the curable composition is not more than the above upper limit value, the adhesiveness with the polarizing film is good.

The curable composition may contain another polymerizable compound (A5) different from the polymerizable compounds (A1) to (A4). Examples of the other polymerizable compound (A5) include a monoepoxy compound and the like. The other polymerizable compound (A5) may be an aliphatic compound, an alicyclic compound or an aromatic compound, or a mixture thereof.
When the curable composition contains another polymerizable compound (A5) as the polymerizable compound, the content thereof is based on 100% by mass of the total amount of the polymerizable compounds (A1) to (A5) contained in the curable composition. It is preferably 10% by mass or less, and more preferably 5% by mass or less.

The curable composition usually contains a polymerization initiator for initiating the polymerization. Examples of the polymerization initiator include a photocationic polymerization initiator (B). The photocationic polymerization initiator generates a cationic species or Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, or electron beams, and initiates a polymerization reaction of a cationically polymerizable compound. .. Since the photocationic polymerization initiator acts catalytically with light, it is excellent in storage stability and workability even when mixed with a photocationic polymerizable compound. Examples of the compound that produces a cationic species or Lewis acid by irradiation with active energy rays include onium salts such as aromatic iodonium salts and aromatic sulfonium salts, aromatic diazonium salts, and iron-alene complexes.

The aromatic iodonium salt is a compound having a diaryliodonium cation, and examples of the cation include a diphenyliodonium cation. The aromatic sulfonium salt is a compound having a triarylsulfonium cation, and examples of the cation include a triphenylsulfonium cation and a 4,4'-bis (diphenylsulfonio) diphenylsulfide cation. The aromatic diazonium salt is a compound having a diazonium cation, and typical examples of the cation include a benzenediazonium cation. The iron-arene complex is typically a cyclopentadienyl iron (II) arene-cationic complex salt.

The cations shown above are paired with anions (anions) to form a photocationic polymerization initiator. Examples of anions which constitute the photo-cationic polymerization initiator, a special phosphorus based anions _{[(Rf) n PF 6-} n] -, hexafluorophosphate anion PF ₆ ^-, hexafluoroantimonate anion SbF ₆ ^-, pentafluorophenyl hydroxy antimonate anion SbF ₅ (OH) ^-, hexafluoro ah cell anions AsF ₆ ^-, tetrafluoroborate anion BF ₄ ^-, tetrakis (pentafluorophenyl) borate anion _{B (C 6 F 5) 4} - and the like. Among them, from the viewpoint of safety of the curability and the resulting cured product layer of the cationically polymerizable compound, a special phosphate based anionic _{[(Rf) n PF 6-} n] -, hexafluorophosphate anion PF ₆ ^- it is preferably ..

As the photocationic polymerization initiator (B), only one type may be used alone, or two or more types may be used in combination. Among them, the aromatic sulfonium salt is preferably used because it has an ultraviolet absorbing property even in a wavelength region near 300 nm, and therefore has excellent curability and can give a cured product having good mechanical strength and adhesive strength.

The blending amount of the photocationic polymerization initiator (B) is usually 0.5 to 10 parts by mass, preferably 6 parts by mass or less, based on 100 parts by mass of the polymerizable compound. By blending 0.5 parts by mass or more of the photocationic polymerization initiator (B), the polymerizable compound can be sufficiently cured, and has high mechanical strength and adhesion to the cured product layer composed of the obtained cured product. Strength and can be given. On the other hand, if the amount is excessively large, the product from the photocationic polymerization initiator may react with the hydroxyl group of the polyvinyl alcohol-based resin constituting the polarizing film to deteriorate the optical performance of the polarizing film.

In the present invention, the curable composition may contain additives generally used in the curable composition, if necessary. Examples of such additives include ion trapping agents, antioxidants, chain transfer agents, polymerization accelerators (polyols, etc.), sensitizers, sensitizers, photostabilizers, tackifiers, and thermoplastic resins. , Fillers, flow modifiers, plasticizers, defoamers, leveling agents, silane coupling agents, dyes, antistatic agents, UV absorbers and the like.

The photosensitizer is a compound that exhibits maximum absorption at a wavelength longer than the maximum absorption wavelength indicated by the photocationic polymerization initiator (B) and promotes the polymerization initiation reaction by the photocationic polymerization initiator (B). The photosensitizer is a compound that further promotes the action of the photosensitizer. Depending on the type of protective film, it may be preferable to add such a photosensitizer and further a photosensitizer.

The photosensitizer is preferably a compound that exhibits maximum absorption in light having a wavelength longer than 380 nm. The photocationic polymerization initiator (B) exhibits maximum absorption at a wavelength near 300 nm or shorter, generates a cationic species or Lewis acid in response to light at a wavelength near that, and cationically polymerizes a polymerizable compound. However, if a photosensitizer as described above is blended, it becomes sensitive to light having a wavelength longer than that, particularly a wavelength longer than 380 nm. As such a photosensitizer, an anthracene-based compound is advantageously used. Specific examples of anthracene-based photosensitizers include the following compounds.

9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-diisopropoxyanthracene, 9,10-dibutoxyanthracene, 9,10-dipentyloxyanthracene, 9, 10-Dihexyloxyanthracene, 9,10-bis (2-methoxyethoxy) anthracene, 9,10-bis (2-ethoxyethoxy) anthracene, 9,10-bis (2-butoxyethoxy) anthracene, 9,10-bis (3-Butoxypropoxy) anthracene, 2-methyl- or 2-ethyl-9,10-dimethoxyanthracene, 2-methyl- or 2-ethyl-9,10-diethoxyanthracene, 2-methyl- or 2-ethyl- 9,10-dipropoxyanthracene, 2-methyl- or 2-ethyl-9,10-diisopropoxyanthracene, 2-methyl- or 2-ethyl-9,10-dibutoxyanthracene, 2-methyl- or 2- Ethyl-9,10-dipentyloxyanthracene, 2-methyl- or 2-ethyl-9,10-dihexyloxyanthracene, etc.

In the polarizing plate of the present invention, the first cured product layer is, for example, the polymerizable compounds (A1) to (A2) and the photocationic polymerization initiator (B), and if necessary, the polymerizable compounds (A1) to (A1) to ( When the curable composition obtained by mixing the polymerizable compounds (A3) to (A5) other than A2) and the additive is placed on a polarizing film or when a first transparent protective film is used, this first It can be formed by applying it on a transparent protective film, irradiating it with active energy rays such as ultraviolet rays and electron beams, and curing the applied curable composition. When the layer made of the curable composition is irradiated with active energy rays, a cationic species or Lewis acid is generated from the photocationic polymerization initiator. With this cation species or Lewis acid, the polymerization of the polymerizable compound proceeds even after irradiation with active energy rays, whereby the curable composition is cured and a cured product layer is formed.

In the polarizing plate of the present invention, the thickness of the first cured product layer is not particularly limited, but is preferably in the range of 0.5 to 20 μm, and more preferably in the range of 1 to 10 μm. When the thickness of the first cured product layer is within the above lower limit value or more, the movement of the ionic compound can be effectively suppressed. When the thickness of the first cured product layer is not more than the upper limit value, the curable composition can be sufficiently cured, and the first cured product layer having high hardness can be obtained.

The polarizing plate of the present invention includes a first cured product layer composed of a cured product of the curable composition between the polarizing film and the adhesive layer, or between the polarizing film and the transparent protective film. Therefore, it is possible to prevent the ionic compound contained in the adhesive layer from moving to the polarizing film. In particular, in a high temperature and high humidity environment, the movement of the ionic compound is accelerated by the invasion of water from the outside, but this can be effectively suppressed by the polarizing plate of the present invention. Therefore, the polarizing plate of the present invention can maintain the optical performance.
The first cured product layer also serves as an adhesive layer for adhering the polarizing film and the transparent protective film.

[Adhesive layer]
As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, conventionally known pressure-sensitive adhesives can be used without particular limitation. For example, a pressure-sensitive adhesive having a base polymer such as acrylic, rubber, urethane, silicone, or polyvinyl ether can be used. Can be used. Further, it may be an energy ray-curable pressure-sensitive adhesive, a thermosetting pressure-sensitive adhesive, or the like. Among these, an adhesive using an acrylic resin as a base polymer, which is excellent in transparency, adhesive strength, reworkability, weather resistance, heat resistance, etc., is preferable.

When the adhesive layer contains an acrylic resin in the present invention, the acrylic resin is not particularly limited, and conventionally known ones can be used, but from the viewpoint of adhesiveness and reworkability, the present invention It is preferable that the adhesive layer contained in the polarizing plate of No. 1 contains the following acrylic resin (P).

〔式中、Ｒ_１は水素原子またはメチル基を表し、Ｒ_２は炭素数１〜１０のアルコキシ基で置換されていてもよい炭素数１〜１４のアルキル基を表す。〕
で示される（メタ）アクリル酸アルキルエステル（Ｐ１）に由来する構造単位を主成分とし、さらに、極性官能基を有する不飽和単量体（Ｐ２）（以下、「極性官能基含有単量体」と称する場合がある）に由来する構造単位を含むアクリル樹脂である。
ここで、本明細書において、（メタ）アクリル酸とは、アクリル酸またはメタクリル酸のいずれでもよいことを意味し、この他、（メタ）アクリレートなどというときの「（メタ）」も同様の趣旨である。 The acrylic resin (P) has the following formula (b):

[In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group having 1 to 14 carbon atoms which may be substituted with an alkoxy group having 1 to 10 carbon atoms. ]
An unsaturated monomer (P2) having a structural unit derived from the (meth) acrylic acid alkyl ester (P1) represented by (P1) as a main component and further having a polar functional group (hereinafter, "polar functional group-containing monomer"). It is an acrylic resin containing a structural unit derived from (sometimes referred to as).
Here, in the present specification, (meth) acrylic acid means that either acrylic acid or methacrylic acid may be used, and "(meta)" in the case of (meth) acrylate or the like also has the same meaning. Is.

In the above formula (b) of the (meth) acrylic acid alkyl ester (P1) which is the main structural unit of the acrylic resin (P), R ₁ is a hydrogen atom or a methyl group, and R ₂ has 1 to 14 carbon atoms. It is an alkyl group. Alkyl group represented by R ₂ is a hydrogen atom in each group may be substituted by an alkoxy group having 1 to 10 carbon atoms.

Among the (meth) acrylic acid alkyl esters (P1) represented by the formula (b), R ₂ is an unsubstituted alkyl group, specifically, methyl acrylate, ethyl acrylate, propyl acrylate, acrylic. Linear alkyl acrylate esters such as n-butyl acid, n-octyl acrylate, and lauryl acrylate; branched alkyl acrylate esters such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate. Linear alkyl methacrylate esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, and lauryl methacrylate; isobutyl methacrylate, 2-ethylhexyl methacrylate, And branched methacrylic acid alkyl esters such as isooctyl methacrylate. Among these, n-butyl acrylate is preferable, and specifically, n-butyl acrylate is preferably 50% by mass or more with respect to the total amount of all the monomers constituting the acrylic resin (P).

Alkyl group R ₂ is substituted with an alkoxy group, i.e., when it is alkoxyalkyl groups, as represented by (meth) acrylic acid alkyl ester with formula (b), specifically, 2-methoxyethyl acrylate, Examples thereof include ethoxymethyl acrylate, 2-methoxyethyl methacrylate, and ethoxymethyl methacrylate.

These (meth) acrylic acid alkyl esters (P1) may be used alone or in combination of a plurality of different types.

In the polar functional group-containing monomer (P2), the polar functional group can be a heterocyclic group such as a free carboxyl group, a hydroxyl group, an amino group, and an epoxy ring. The polar functional group-containing monomer is preferably a (meth) acrylic acid-based compound having a polar functional group. Examples thereof are unsaturated monomers having free carboxyl groups such as acrylic acid, methacrylic acid, and β-carboxyethyl acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, ( Unsaturated monomers with hydroxyl groups such as 2- or 3-chloro-2-hydroxypropyl acrylate, and diethylene glycol mono (meth) acrylates; acryloylmorpholin, vinylcaprolactam, N-vinyl-2-pyrrolidone, tetrahydrofur. Unsaturated monomers with heterocyclic groups such as frill (meth) acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl (meth) acrylate, and 2,5-dihydrofuran. ; An unsaturated monomer having an amino group different from that of the heterocycle such as N, N-dimethylaminoethyl (meth) acrylate can be mentioned. The polar functional group is preferably a free carboxyl group, a hydroxyl group, an amino group or an epoxy ring. Each of these polar functional group-containing monomers may be used alone, or a plurality of different types may be used.

Among these, it is preferable to include an unsaturated monomer having a hydroxyl group as one of the polar functional group-containing monomers (P2) constituting the acrylic resin (P). Further, in addition to the unsaturated monomer having a hydroxyl group, it is also effective to use an unsaturated monomer having another polar functional group, for example, an unsaturated monomer having a free carboxyl group in combination.

In the acrylic resin (P), the structural unit derived from the (meth) acrylic acid alkyl ester (P1) represented by the above formula (b) is 80 with respect to the total amount of all the monomers constituting the acrylic resin (P). It is preferably ~ 96% by mass, more preferably 82% by mass or more, and more preferably 94% by mass or less. The structural unit derived from the polar functional group-containing monomer (P2) is preferably 0.1 to 5% by mass, more preferably 0.1 to 5% by mass, based on the total amount of all the monomers constituting the acrylic resin (P). It is 0.5% by mass or more, and more preferably 3% by mass or less.

In the polarizing plate of the present invention, the acrylic resin (P) that can form the adhesive layer includes the (meth) acrylic acid alkyl ester (P1) represented by the above formula (b) and the polar functional group-containing monomer (P2). May contain structural units derived from different monomers. Examples of these may be unsaturated monomers (P3) having one olefinic double bond and at least one aromatic ring in the molecule (hereinafter, referred to as "aromatic ring-containing monomer"). ), A structural unit derived from a (meth) acrylic acid ester having an alicyclic structure in the molecule, a structural unit derived from a styrene-based monomer, a structural unit derived from a vinyl-based monomer, a molecule. Examples thereof include structural units derived from monomers having a plurality of (meth) acryloyl groups.

〔式中、Ｒ_３は水素原子またはメチル基を表し、ｎは１〜８の整数であり、Ｒ_４は水素原子、アルキル基、アラルキル基またはアリール基を表す〕
で示される芳香環含有（メタ）アクリル化合物が好ましい。 An unsaturated monomer (aromatic ring-containing monomer) (P3) having one olefinic double bond and at least one aromatic ring in the molecule is a group containing an olefinic double bond (meth). Those having an acryloyl group are preferable. Examples thereof include benzyl (meth) acrylate and neopentyl glycol benzoate (meth) acrylate. Among them, the following formula (c):

[In the formula, R ₃ represents a hydrogen atom or a methyl group, n is an integer of 1 to 8, and R ₄ represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group]
The aromatic ring-containing (meth) acrylic compound represented by is preferable.

In the above formula (c) representing an aromatic ring-containing (meth) acrylic compound, when R ₄ is an alkyl group, its carbon number can be 1 to 9, and when it is also an aralkyl group, its carbon number is In the case of 7 to 11 and an aryl group, the number of carbon atoms can be 6 to 10. Methyl, butyl, nonyl and the like as alkyl groups having 1 to 9 carbon atoms, benzyl, phenethyl, naphthylmethyl and the like as aralkyl groups having 7 to 11 carbon atoms, and phenyl as aryl groups having 6 to 10 carbon atoms. Trill, naphthyl, etc. are mentioned respectively.

Specific examples of the aromatic ring-containing (meth) acrylic compound of the formula (c) include (meth) acrylic acid 2-phenoxyethyl, (meth) acrylic acid 2- (2-phenoxyethoxy) ethyl, and ethylene oxide-modified nonylphenol (. Examples thereof include meta) acrylic acid ester and 2- (o-phenylphenoxy) ethyl (meth) acrylic acid. Each of these aromatic ring-containing monomers may be used alone, or a plurality of different types may be used in combination. Among these, [in the formula _(c), R 4 = H, the compound of n = 1] (meth) 2-phenoxyethyl acrylate, (meth) acrylic acid 2- (o-phenylphenoxy) ethyl [the formula In (c), R ₄ = o-phenyl, n = 1 compound] or 2- (2-phenoxyethoxy) ethyl (meth) acrylate [in the above formula (c), R ₄ = H, n = 2 Compound] is suitable as one of the aromatic ring-containing monomers (P3) constituting the acrylic resin (P).

The alicyclic structure is a cycloparaffin structure having usually 5 or more carbon atoms, preferably 5 to 7 carbon atoms. Specific examples of the acrylic acid ester having an alicyclic structure include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methyl cyclohexyl acrylate, trimethylcyclohexyl acrylate, and tert-butyl cyclohexyl acrylate. , Cyclohexyl α-ethoxyacrylate, cyclohexylphenyl acrylate and the like, and specific examples of the methacrylic acid ester having an alicyclic structure include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate and cyclododecyl methacrylate. , Methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, cyclohexylphenyl methacrylate and the like.

Specific examples of the styrene-based monomer include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene. Alkyl styrene; halogenated styrene such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; further, nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene and the like can be mentioned.

Specific examples of vinyl-based monomers include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanate, and vinyl laurate; halogenation of vinyl chloride and vinyl bromide. Vinyl; vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene; as well as acrylonitrile, methacrylate. Lonitrile and the like can be mentioned.

Specific examples of the monomer having a plurality of (meth) acryloyl groups in the molecule include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 1,9-nonane. Two (meth) in the molecule such as diol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and tripropylene glycol di (meth) acrylate. ) Monomer having an acryloyl group; a monomer having three (meth) acryloyl groups in a molecule such as trimethylpropantri (meth) acrylate can be mentioned.

Monomers different from the (meth) acrylic acid alkyl ester (P1) represented by the formula (b) and the polar functional group-containing monomer (P2) can be used alone or in combination of two or more. it can. When contained in the pressure-sensitive adhesive, the structural unit derived from a monomer different from the (meth) acrylic acid alkyl ester (P1) and the polar functional group-containing monomer (P2) in the acrylic resin (P) is the resin. It is usually contained in an amount of 0 to 20 parts by mass, preferably 0 to 10 parts by mass with respect to 100 parts by mass of the non-volatile content.

The resin component constituting the pressure-sensitive adhesive composition is an acrylic resin containing a (meth) acrylic acid alkyl ester (P1) represented by the above formula (b) and a structural unit derived from a polar functional group-containing monomer (P2). It may contain two or more types. Further, the acrylic resin (P) is mixed with an acrylic resin different from that, for example, an acrylic resin having a structural unit derived from the (meth) acrylic acid alkyl ester of the formula (b) and containing no polar functional group. May be used. The acrylic resin (P) containing the structural unit derived from the (meth) acrylic acid alkyl ester (P1) represented by the formula (b) and the polar functional group-containing monomer (P2) is added to the total amount of the acrylic resin (P). On the other hand, it is preferably 80% by mass or more, more preferably 90% by mass or more.

The acrylic resin (P), which is a copolymer of a monomer mixture containing the (meth) acrylic acid alkyl ester (P1) represented by the formula (b) and the polystyrene functional group-containing monomer (P2), is gel permeation. The weight average molecular weight Mw converted to standard polystyrene by ion chromatography (GPC) is preferably in the range of 1 million to 2 million. When the weight average molecular weight in terms of standard polystyrene is within the above range, the adhesiveness under high temperature and high humidity tends to be improved, and the possibility of peeling or floating between the liquid crystal cell and the adhesive layer tends to be low. Further, the reworkability tends to be improved. Further, even if the size of the polarizing plate attached to the adhesive layer changes, the adhesive layer tends to fluctuate according to the change in the size, and the brightness between the peripheral portion and the central portion of the liquid crystal cell is increased. There is no difference in color, and there is a tendency for white spots and uneven color to be suppressed.

The molecular weight distribution represented by the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is preferably in the range of 3 to 7. When the molecular weight distribution Mw / Mn is in the range of 3 to 7, it is possible to suppress the occurrence of defects such as white spots even when the liquid crystal display panel or the liquid crystal display device is exposed to a high temperature.

Further, the acrylic resin (P) preferably has a glass transition temperature in the range of −10 to −60 ° C. from the viewpoint of developing adhesiveness. The glass transition temperature of a resin can generally be measured by a differential scanning calorimeter.

The acrylic resin (P) constituting the pressure-sensitive adhesive composition can be produced by various known methods such as a solution polymerization method, an emulsion polymerization method, a massive polymerization method, and a suspension polymerization method. In the production of this acrylic resin, a polymerization initiator is usually used. The content of the polymerization initiator is preferably 0.001 to 5 parts by mass with respect to 100 parts by mass in total of all the monomers used in the production of the acrylic resin.

As the polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator and the like are used. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone. Examples of the thermal polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), and 1,1'-azobis (cyclohexane-1-carbonitrile). 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis (2-methylpropio) Nate), and azo compounds such as 2,2'-azobis (2-hydroxymethylpropionitrile); lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroper. Organics such as oxides, diisopropylperoxydicarbonates, dipropylperoxydicarbonates, tert-butylperoxyneodecanoates, tert-butylperoxypivalates, and (3,5,5-trimethylhexanoyl) peroxides. Peroxides: Inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide can be mentioned. In addition, a redox-based initiator in which a peroxide and a reducing agent are used in combination can also be used as the polymerization initiator.

As a method for producing the acrylic resin (P), a solution polymerization method is particularly preferable. To explain a specific example of the solution polymerization method, a desired monomer and an organic solvent are mixed, a thermal polymerization initiator is added under a nitrogen atmosphere, and the temperature is 40 to 90 ° C, preferably 50 to 80 ° C. A method of stirring for 10 hours can be mentioned. Further, in order to control the reaction, the monomer or the thermal polymerization initiator may be added continuously or intermittently during the polymerization, or may be added in a state of being dissolved in an organic solvent. Here, examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propyl alcohol and isopropyl alcohol; acetone, methyl ethyl ketone, and methyl isobutyl. Ketones such as ketone can be used.

The pressure-sensitive adhesive layer contained in the polarizing plate of the present invention is preferably formed by using an acrylic resin (P) and a cross-linking agent in combination. The cross-linking agent that can be used is, for example, a compound that reacts with a structural unit derived from a polar functional group-containing monomer (P2) in the acrylic resin (P) to cross-link the acrylic resin. Specific examples thereof include isocyanate compounds, epoxy compounds, aziridine compounds, and metal chelate compounds. Of these, the isocyanate-based compound, the epoxy-based compound, and the aziridine-based compound have at least two functional groups in the molecule that can react with the polar functional groups in the acrylic resin (P).

The isocyanate-based compound is a compound having at least two isocyanato groups (-NCO) in the molecule, and is, for example, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, etc. Examples thereof include hydrogenated diphenylmethane diisocyanate, naphthalenediocyanate, and triphenylmethane triisocyanate. Further, an adduct compound obtained by reacting these isocyanate compounds with a polyol such as glycerol or trimethylolpropane, or a dimer or trimer of an isocyanate compound can also be used as a cross-linking agent for an adhesive. .. It is also possible to use a mixture of two or more kinds of isocyanate compounds.

The epoxy compound is a compound having at least two epoxy groups in the molecule, and is, for example, a bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether. , 1,6-Hexanediol diglycidyl ether, trimethylpropan triglycidyl ether, N, N-diglycidyl aniline, N, N, N', N'-tetraglycidyl-m-xylene diamine, 1,3-bis ( N, N'-diglycidylaminomethyl) cyclohexane and the like can be mentioned. It is also possible to use a mixture of two or more kinds of epoxy compounds.

The aziridine-based compound is a compound having at least two 3-membered ring skeletons consisting of one nitrogen atom and two carbon atoms, also called ethyleneimine, in the molecule. For example, diphenylmethane-4,4'-bis. (1-Aziridine Carboxamide), Toluene-2,4-Bis (1-Aziridine Carboxamide), Triethylene Melamine, Isophthaloylbis-1- (2-Methyl Aziridine), Tris-1-aziridinylphosphine oxide, Hexa Examples thereof include methylene-1,6-bis (1-aziridinecarboxamide), trimethylpropan tris-β-aziridinyl propionate, and tetramethylolmethane tris-β-aziridinyl propionate.

As the metal chelate compound, acetylacetone or ethyl acetoacetate is coordinated with a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Examples include compounds.

Among these cross-linking agents, isocyanate compounds, especially xylylene diisocyanate, tolylene diisocyanate or hexamethylene diisocyanate, or adducts obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylpropane, and A dimer, a trimer, or the like obtained by combining these isocyanate compounds, a mixture of these isocyanate compounds, and the like are preferably used. It is preferable to use at least one isocyanate-based compound as the cross-linking agent, especially when the polar functional group-containing monomer (P2) has a polar functional group selected from a free carboxyl group, a hydroxyl group, an amino group and an epoxy ring. .. Among them, as suitable isocyanate compounds, tolylene diisocyanate, an adduct obtained by reacting tolylene diisocyanate with a polyol, a dimer of tolylene diisocyanate, a trimeric of tolylene diisocyanate, hexamethylene diisocyanate, and hexamethylene diisocyanate. Examples thereof include an adduct compound obtained by reacting with a polyol, a hexamethylene diisocyanate dimer, and a hexamethylene diisocyanate trimeric.

In the pressure-sensitive adhesive layer constituting the polarizing plate of the present invention, the amount of the cross-linking agent is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the acrylic resin (P). The content of the cross-linking agent is more preferably 0.1 to 5 parts by mass, and further preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the acrylic resin (P). When the amount of the cross-linking agent is within the above range, the durability of the adhesive layer tends to be improved, and the white spots on the liquid crystal display panel tend to be inconspicuous, which is preferable.

In the present invention, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer preferably contains a silane-based compound, and in particular, it is preferable to contain the silane-based compound in the acrylic resin before blending the cross-linking agent. Since the silane compound improves the adhesive strength to the glass, the adhesion between the liquid crystal cell sandwiched between the glass substrates and the adhesive layer is improved by containing the silane compound, and high adhesive strength to the display panel is ensured. Can be done.

Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, and N- (2-amino). Ethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl Trimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-gly Examples thereof include sidoxylpropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, and 3-glycidoxypropylethoxydimethylsilane. These silane compounds may be used alone or in combination of two or more.

The silane compound may be of the silicone oligomer type. When the silicone oligomer is shown in the form of (monomer)-(monomer) copolymer, for example, the following can be mentioned.
3-Mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxy. A mercaptopropyl group-containing copolymer, such as a silane copolymer;
Mercaptomethyl, such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer. Group-containing copolymer;
3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane -Tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and Copolymers containing a methacryloyloxypropyl group, such as 3-methacryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer;
3-Acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane -Tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and Copolymers containing acryloyloxypropyl groups, such as 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymers;
Vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, Vinyl group-containing copolymers such as vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer;
3-Aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetraethoxysilane Copolymers, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-aminopropylmethyldiethoxy Amino group-containing copolymers such as silane-tetraethoxysilane copolymers.

These silane compounds are often liquids. The blending amount of the silane compound in the pressure-sensitive adhesive is usually 0.01 to 10 parts by mass, preferably 0.01 to 10 parts by mass, based on 100 parts by mass of the non-volatile content of the acrylic resin (P) (the total amount when two or more types are used). The ratio is 0.03 to 1 part by mass. When the amount of the silane compound with respect to 100 parts by mass of the non-volatile content of the acrylic resin (P) is within the above range, the adhesion between the adhesive layer and the liquid crystal cell is improved, which is preferable, and bleeding of the silane compound from the adhesive layer. It is preferable because the out tends to be suppressed.

In the present invention, the adhesive layer contains an ionic compound. The ionic compound can function as an antistatic agent. In particular, when the acrylic resin (P) contains an aromatic ring-containing (meth) acrylic compound represented by the above formula (c) and n in the formula (c) is 2 or more, it is effective in suppressing whitening. By blending an ionic compound in a pressure-sensitive adhesive containing an acrylic resin in which this monomer is copolymerized, it is possible to impart a good antistatic property while imparting an effect of suppressing whitening. The ionic compound referred to here is a compound existing as a combination of a cation and an anion, and the cation and the anion may be inorganic or organic, respectively, but the acrylic resin (P) and From the viewpoint of compatibility with the above, it is preferable that at least one of the cation and the anion is an ionic compound containing an organic group.

Examples of inorganic cations constituting ionic compounds include alkali metal ions such as lithium cation [Li ⁺ ], sodium cation [Na ⁺ ], potassium cation [K ⁺ ], and cesium cation [Cs ⁺ ]; beryllium cation [Be]. ^Examples thereof include alkaline earth metal ions such as ²⁺ ], magnesium cation [Mg ²⁺ ], and calcium cation [Ca ²⁺ ]. Among them, from the viewpoint of metal corrosion resistance, it is preferable to use lithium cation [Li ⁺ ], potassium cation [K ⁺ ] or sodium cation [Na ⁺ ], and from the viewpoint of durability, potassium cation [K ⁺ ] is used. It is more preferable to use it.

Examples of the organic cations constituting the ionic compound include pyridinium-based cations represented by the following formula (d): and quaternary ammonium cations represented by the following formula (e).

In the formula (d), R _{5 to} R ₉ independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₁₀ represents an alkyl group having 1 to 16 carbon atoms. In formula (e), R ₁₁ represents an alkyl group having 1 to 12 carbon atoms, and R ₁₂ , R ₁₃ and R ₁₄ each independently represent an alkyl group having 6 to 12 carbon atoms.

The pyridinium-based cation represented by the above formula (d) has a total carbon number of 6 or more, and among them, a total carbon number of 8 or more, particularly 10 or more is a viewpoint of compatibility with the acrylic resin (P). Is preferable. The total carbon number is preferably 36 or less, more preferably 30 or less. Among the pyridinium-based cations represented by the formula (d), R ₇ bonded to the 4-position carbon atom of the pyridine ring is an alkyl group, and R ₅ , R ₆ and R bonded to other carbon atoms of the pyridine ring. One of the preferred cations is one in which ₈ and R ₉ are hydrogen atoms, respectively.

Specific examples of the pyridinium-based cation represented by the formula (d) include the following.
N-Methyl-4-hexylpyridinium cation, N-butyl-4-methylpyridinium cation, N-butyl-2,4-diethylpyridinium cation, N-butyl-2-hexylpyridinium cation, N-hexyl-2-butylpyridinium Cation, N-hexyl-4-methylpyridinium cation, N-hexyl-4-ethylpyridinium cation, N-hexyl-4-butylpyridinium cation, N-octyl-4-methylpyridinium cation, N-octyl-4-ethylpyridinium Cation, N-octylpyridinium cation, etc.

The ammonium cation represented by the above formula (e) is a tetraalkylammonium cation, and the tetraalkylammonium cation has a total carbon number of 20 or more and further 22 or more, which is the phase with the acrylic resin (P). It is preferable from the viewpoint of solubility. Further, the total carbon number is preferably 36 or less, more preferably 30 or less.

Specific examples of the tetraalkylammonium cation represented by the formula (e) include the following.
Tetrahexyl ammonium cation, tetraoctyl ammonium cation, tributyl methyl ammonium cation, trihexyl methyl ammonium cation, trioctyl methyl ammonium cation, tridecyl methyl ammonium cation, trihexyl ethyl ammonium cation, trioctyl ethyl ammonium cation, etc.

On the other hand, examples of anions constituting an ionic compound include the following.
Chloride anion [Cl ⁻ ], bromide anion [Br ⁻ ], iodide anion [I ⁻ ], tetrachloroaluminate anion [AlCl ^4- ], heptachlorodialuminate anion [Al ₂ Cl ₇ ⁻ ], tetrafluoroborate anion [BF ₄ ^-], hexafluorophosphate anion [PF ₆ ^-], perchlorate anion [ClO ₄ ^-], nitrate anion [NO ₃ ^-], acetate anion _[CH 3 COO ^-], trifluoroacetate anion [CF ₃ COO ⁻ ], methanesulfonate anion [CH ₃ SO ₃ ⁻ ], trifluoromethanesulfonate anion [CF ₃ SO ₃ ⁻ ], bis (trifluoromethanesulfonyl) imide anion [(CF ₃ SO ₂ ) ₂ N ⁻ ], Tris ( Trifluoromethanesulfonyl) methanide anion [(CF ₃ SO ₂ ) ₃ C ⁻ ], hexafluoroarsenate anion [AsF ₆ ⁻ ], hexafluoroantimonate anion [SbF ₆ ⁻ ], hexafluoroniobate anion [NbF ₆ ^−] ], hexafluoro tantalate anion [TaF ₆ ^-], (poly) hydrofluoroether fluoride anion [F _{(HF) n} ^-] (n is about 1 to 3), thiocyanate anion [SCN ^-], dicyanamide anion [( CN) ₂ N ⁻ ], perfluorobutane sulfonate anion [C ₄ F ₉ SO ₃ ⁻ ], bis (pentafluoroethane sulfonyl) imide anion [(C ₂ F ₅ SO ₂ ) ₂ N ⁻ ], perfluorobutanoate Anions [C ₃ F ₇ COO ⁻ ], (trifluoromethanesulfonyl) (trifluoromethanecarbonyl) imide anions [(CF ₃ SO ₂ ) (CF ₃ CO) N ⁻ ], etc.

Specific examples of the ionic compound can be appropriately selected from the above-mentioned combinations of cations and anions. Specific examples of the ionic compound which is a combination of a cation and an anion include the following.
Lithium bis (trifluoromethanesulfonyl) imide, lithium hexafluorophosphate, lithium iodide (lithium iodide), lithium bis (pentafluoroethanesulfonyl) imide, lithium tris (trifluoromethanesulfonyl) methanide, sodium bis (trifluoromethanesulfonyl) imide, Sodium bis (pentafluoroethanesulfonyl) imide, sodium tris (trifluoromethanesulfonyl) metanide, potassium bis (trifluoromethanesulfonyl) imide, potassium bis (pentafluoroethanesulfonyl) imide, potassium tris (trifluoromethanesulfonyl) metanide, N-methyl -4-Hexylpyridinium bis (trifluoromethanesulfonyl) imide, N-butyl-2-methylpyridinium bis (trifluoromethanesulfonyl) imide, N-hexyl-4-methylpyridinium bis (trifluoromethanesulfonyl) imide, N-octyl-4 -Methylpyridinium bis (trifluoromethanesulfonyl) imide, N-methyl-4-hexylpyridinium hexafluorophosphate, N-butyl-2-methylpyridinium hexafluorophosphate, N-hexyl-4-methylpyridinium hexafluorophosphate, N-octyl -4-Methylpyridinium hexafluorophosphate, N-methyl-4-hexylpyridinium percolate, N-butyl-2-methylpyridinium percolate, N-hexyl-4-methylpyridinium percolate, N-octyl-4-methylpyridinium Parklolate, tetrahexyl ammonium bis (trifluoromethanesulfonyl) imide, tributylmethylammonium bis (trifluoromethanesulfonyl) imide, trihexylmethylammonium bis (trifluoromethanesulfonyl) imide, trioctylmethylammonium bis (trifluoromethanesulfonyl) imide, tetra Hexylammonium Hexafluorophosphate, Tributylmethylammonide Hexafluorophosphate, Trihexylmethylammonium Hexafluorophosphate, Trioctylmethylammonium Hexafluorophosphate, Tetrahexylammonium percolate, Tributylmethylammonium pa -Chlorate, trihexylmethylammonium percolate, trioctylmethylammonium percolate, etc.

These ionic compounds can be used alone or in combination of two or more. The content of the ionic compound is usually 0.5 to 8 parts by mass, preferably 0.8 to 4 parts by mass with respect to 100 parts by mass of the acrylic resin (P).

In the present invention, the adhesive layer may further contain a cross-linking catalyst, a weather-resistant stabilizer, a tack fire, a plasticizer, a softening agent, a dye, a pigment, an inorganic filler, a resin other than an acrylic resin, and the like. It is also useful to blend an ultraviolet curable compound such as a polyfunctional acrylate and a photoinitiator into the pressure-sensitive adhesive, and after forming the pressure-sensitive adhesive layer, irradiate the pressure-sensitive adhesive with ultraviolet rays to cure the pressure-sensitive adhesive layer to obtain a harder pressure-sensitive adhesive layer. This embodies a second crosslinked structure in the adhesive and plays a role in improving durability during heat resistance and the like. Further, if a cross-linking catalyst is used together with the cross-linking agent in the pressure-sensitive adhesive, the pressure-sensitive adhesive layer can be prepared by aging in a short time, and the obtained polarizing plate containing the pressure-sensitive adhesive may float between the polarizing plate and the pressure-sensitive adhesive layer. It is possible to suppress the occurrence of peeling and the occurrence of foaming in the adhesive layer, and the reworkability may be improved.

Examples of the cross-linking catalyst include amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resin, and melamine resin. it can. When an amine compound is blended with the pressure-sensitive adhesive as a cross-linking catalyst, an isocyanate compound is preferable as the cross-linking agent.

Further, it is also possible to form an adhesive layer that contains fine particles and exhibits light scattering properties. Further, the adhesive layer may contain an antioxidant, an ultraviolet absorber, or the like. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex salt compounds.

The adhesive layer may be provided by, for example, using the above-mentioned adhesive as an organic solvent solution, applying it on a film or layer (for example, a polarizing film) on which the adhesive is to be laminated with a die coater or a gravure coater, and drying the adhesive layer. it can. It can also be provided by a method of transferring a sheet-like adhesive formed on a plastic film (called a separate film) that has been subjected to a mold release treatment to a film or layer to be laminated. The thickness of the adhesive layer is not particularly limited, but is preferably in the range of 2 to 40 μm, more preferably in the range of 5 to 35 μm, and further preferably in the range of 10 to 30 μm. ..

The storage elastic modulus of the adhesive layer is preferably 0.10 to 5.0 MPa, more preferably 0.15 to 1.0 MPa at 23 to 80 ° C. When the storage elastic modulus at 23 to 80 ° C. is 0.10 MPa or more, it is possible to suppress whitening due to shrinkage of the polarizing plate when the liquid crystal display panel in which the polarizing plate is attached to the liquid crystal cell is exposed to high temperature or the like. Therefore, it is preferable. Further, when it is 5 MPa or less, the durability is less likely to be lowered due to the decrease in the adhesive strength, which is preferable. Here, "showing a storage elastic modulus of 0.10 to 5.0 MPa at 23 to 80 ° C." means that the storage elastic modulus takes a value in the above range at any temperature in this range. Since the storage elastic modulus usually gradually decreases as the temperature rises, if the storage elastic modulus at 23 ° C. and 80 ° C. is both within the above range, the adhesive layer has the storage elastic modulus within the above range at the temperature in this range. Can be seen as showing. The storage elastic modulus of the adhesive layer can be measured by a commercially available viscoelasticity measuring device, for example, a viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETRIC.

In a preferred embodiment, the adhesive layer of the polarizing plate of the present invention is an acrylic resin or silane which is a copolymer of butyl acrylate, methyl acrylate, 2-hydroxyethyl acrylate, 2-phenoxyethyl acrylate and acrylic acid. It is composed of a system compound, an isocyanate compound as a cross-linking agent, and an antistatic component.

[Polarizing film]
The polarizing film constituting the polarizing plate of the present invention is a film having a function of extracting linearly polarized light from incident natural light. In the present invention, a polyvinyl alcohol-based resin film is contained with a bicolor dye and is adsorbed and oriented. It is a film. As the polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin film, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith (for example, ethylene-vinyl acetate copolymer weight). Coalescence, etc.). Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc. modified with aldehydes can be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 to 10000, preferably 1500 to 5000.

A film formed from such a polyvinyl alcohol-based resin can be used as a raw film for a polarizing film. The method for forming the film of the polyvinyl alcohol-based resin is not particularly limited, and the film can be formed by a conventionally known method. The thickness of the raw film made of the polyvinyl alcohol-based resin is not particularly limited, but is, for example, 10 to 150 μm, preferably 15 to 100 μm, and more preferably 15 to 100 μm, considering the ease of stretching. It is 20 to 80 μm.

The polarizing film is usually a step of uniaxially stretching such a polyvinyl alcohol-based resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and a dichroic dye. It is produced through a step of treating the adsorbed polyvinyl alcohol-based resin film with an aqueous boric acid solution and a step of washing with water after the treatment with the aqueous boric acid solution.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before dyeing the dichroic dye, at the same time as dyeing, or after dyeing. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. It is also possible to perform uniaxial stretching in these a plurality of steps. In uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched, or thermal rolls may be used to uniaxially stretch. Further, the uniaxial stretching may be a dry stretching performed in the atmosphere, or a wet stretching performed in a state where the polyvinyl alcohol-based resin film is swollen using a solvent. The draw ratio is preferably 8 times or less, more preferably 7.5 times or less, still more preferably 7 times or less, from the viewpoint of suppressing deformation of the polarizing film. Further, the draw ratio is preferably 4.5 times or more from the viewpoint of exhibiting the function as a polarizing film.

Examples of the method of dyeing the polyvinyl alcohol-based resin film with the dichroic dye include a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, for example, iodine or a dichroic dye is used. For dichroic dyes, for example, C.I. I. Included are dichroic direct dyes made of disazo compounds such as DIRECT RED 39, and dichroic direct dyes made of trisazo, tetrakisazo compounds and the like. The polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide for dyeing is usually adopted. The iodine content in this aqueous solution is usually 0.01 to 1 part by mass per 100 parts by mass of water, and the content of potassium iodide is usually 0.5 to 20 parts by mass per 100 parts by mass of water. .. When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 20 to 1800 seconds.

When a dichroic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye and dyeing is usually adopted. The content of the dichroic dye in this aqueous solution, usually, 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water, preferably 1 × 10 ^-3 to 1 parts by weight, particularly preferably 1 × 10 ^{- 3} to 1 x 10 ^-2 parts by mass. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. When a dichroic dye is used as the dichroic dye, the temperature of the dye aqueous solution used for dyeing is usually 20 to 80 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 10 to 1800 seconds. is there.

The boric acid treatment after dyeing with a dichroic dye can be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually 2 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. The immersion time in the boric acid-containing aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., and more preferably 60 to 80 ° C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of water in the washing treatment is usually 5 to 40 ° C., and the immersion time is usually 1 to 120 seconds. After washing with water, a drying treatment is performed to obtain a polarizing film. The drying process can be performed using a hot air dryer or a far-infrared heater. The temperature of the drying treatment is usually 30 to 100 ° C., preferably 40 to 95 ° C., more preferably 50 to 90 ° C. The drying treatment time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

As described above, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment to obtain a polarizing film. The thickness of the polarizing film can be, for example, 5 to 40 μm.

[Second cured product layer]
The polarizing plate of the present invention may have a second cured product layer composed of a cured product of a curable composition on a surface of the polarizing film opposite to the first cured product layer. The curable composition forming the cured product constituting the second cured product layer may be the same as or different from the curable composition of the first cured product layer described above.

In one embodiment of the present invention, the second cured product layer is also used as an adhesive for adhering the polarizing film and the transparent protective film (5 in FIGS. 1 and 2) laminated on the opposite side of the liquid crystal cell. If the curable composition of the second cured product layer is different from the curable composition of the first cured product layer because it is functional, the curable composition of the second cured product layer is known in the art. A photocurable adhesive can be used. Examples of the photocurable adhesive include a mixture of a photocurable epoxy resin and a photocationic polymerization initiator, and a mixture of a photocurable acrylic resin and a photoradical polymerization initiator. The curable composition for forming the cured product constituting the second cured product layer is appropriately selected depending on the adhesiveness to the polarizing film and the second transparent protective film, and is described in, for example, International Publication No. 2014/129368. A photocurable adhesive containing a photocurable component and a photocationic polymerization initiator can be used.

In the present invention, the curable composition (photocurable adhesive) is applied to the surface of the second cured product layer opposite to the surface on which the first cured product layer of the polarizing plate is laminated by a known method. Can be formed by For example, the casting method, the Meyer bar coating method, the gravure coating method, the comma coater method, the doctor blade method, the die coating method, the dip coating method, the spraying method and the like can be used. The casting method is a method in which an adhesive is poured down on the surface of a film to be coated while being moved in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two. After applying the curable composition, the polarizing film and the transparent protective film to be bonded to the polarizing film are laminated, sandwiched by a nip roll or the like, and the film is bonded. The film can be attached using a nip roll, for example, by applying a curable composition and then applying pressure with a roll or the like to spread the film uniformly, or by applying the curable composition and then passing the film between the rolls. , A method of pressurizing and spreading can be adopted. In this case, the material of the roll used may be metal, rubber, or the like. Further, when the film is passed between the plurality of rolls and spread out, the plurality of rolls may be made of the same material or different materials.

When a photocurable adhesive is used, the photocurable adhesive is cured by irradiating it with active energy rays. The light source of the active energy ray is not particularly limited, but an active energy ray having an emission distribution at a wavelength of 400 nm or less is preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, and a black light lamp. , Microwave-excited mercury lamp, metal halide lamp and the like are preferable.

The light irradiation intensity of the photocurable adhesive is appropriately determined by the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is preferably 0.1 to 1. It is 6000 mW / cm ² , more preferably 10 to 1000 mW / cm ² , and even more preferably 20 to 500 mW / cm ² . When the irradiation intensity is within the above range, the reaction time can be secured, and the yellowing of the epoxy resin and the deterioration of the polarizing film due to the heat radiated from the light source and the heat generated during the curing of the photocurable adhesive can be suppressed. Can be done. The light irradiation time of the photocurable adhesive may be appropriately selected depending on the photocurable adhesive to be cured, and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time. It is preferably 10 to 10000 mJ / ^{m 2,} more preferably 50~1000mJ / ^{m 2,} more preferably is set to be 80~500mJ / ^{m 2.} When the integrated amount of light to the photocurable adhesive is within the above range, a sufficient amount of active species derived from the polymerization initiator can be generated, the curing reaction can proceed more reliably, and the irradiation time becomes longer. Not too much, and good productivity can be maintained.

When the photocurable adhesive is cured by irradiation with active energy rays, for example, polarizing plates such as the degree of polarization, transmittance and hue of the polarizing film, and the transparency of the transparent protective film and various films constituting the optical layer are used. It is preferable to perform curing under the condition that the various functions of the above are not deteriorated. The thickness of the second cured product layer is not particularly limited, but is usually 0.1 to 10 μm.
[Transparent protective film]
In one embodiment, the polarizing plate of the present invention has a first transparent protective film (6 in FIG. 2) laminated on one surface of the polarizing film with a first cured product layer interposed therebetween. Further, in one embodiment, the polarizing plate of the present invention has a second transparent protective film (5 in FIGS. 1 and 2) laminated on the other surface of the polarizing film via a second cured product layer. .. In one embodiment, the polarizing plate of the present invention has a transparent protective film from the viewpoint of contributing to the prevention of shrinkage and expansion of the polarizing film and the prevention of deterioration of the polarizing film due to temperature, humidity, ultraviolet rays and the like. On the other hand, in one embodiment, the polarizing plate of the present invention does not include the first transparent protective film from the viewpoint of reducing the thickness of the polarizing plate.

As the material for forming the transparent protective film, a material having excellent transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, and styrene such as polystyrene and acrylonitrile-styrene copolymer (AS resin). Examples thereof include based polymers and polystyrene polymers. Further, polyethylene, polypropylene, polyolefin having a cyclo- or norbornene structure, polyolefin-based polymer such as ethylene / propylene copolymer, vinyl chloride-based polymer, amide-based polymer such as nylon or aromatic polyamide, imide-based polymer, sulfone-based Polymers, polyether sulfone-based polymers, polyether ether ketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, allylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, or Blends of the above polymers are also mentioned as examples of polymers forming a transparent protective film. The transparent protective film can also be formed as a cured layer made of a thermosetting type or ultraviolet curable type resin such as acrylic type, urethane type, acrylic urethane type, epoxy type and silicone type. Among them, those having a hydroxyl group having reactivity with an isocyanate-based cross-linking agent are preferable, and a cellulosic polymer is particularly preferable.

In the polarizing plate of the present invention, the first transparent protective film and the second transparent protective film may be made of the same material or may be made of different materials.

The thickness of the transparent protective film is not particularly limited, but both the first transparent protective film and the second transparent protective film are generally 500 μm or less, preferably 1 to 300 μm, and 5 to 200 μm. It is more preferably present, and further preferably 10 to 100 μm. Further, the transparent protective film may be composed of a transparent protective film or the like to which an optical compensation function is added.

In the polarizing plate of the present invention, since the first cured product layer can effectively suppress the movement of the ionic compound from the adhesive layer to the polarizing film, the material of the first transparent protective film constituting the polarizing plate can be used. Wider selection. That is, it is not necessary to use a transparent protective film that does not easily transmit the ionic compound, and it is possible to construct the polarizing plate by using the transparent protective film that easily transmits the ionic compound. As a result, the polarizing plate of the present invention is advantageous from an industrial point of view, for example, the production cost can be reduced.

Specifically, for example, it is immersed in a 50 mass% potassium iodide aqueous solution in an air atmosphere of 23 ° C. and 60% RH for 4.5 hours, taken out, washed with water at 23 ° C. in the air for 15 seconds, and then washed at 23 ° C. in the air for 15 seconds. A transparent protective film having a absorbance against light having a wavelength of 360 nm after the treatment of drying in a dark place for 15 hours is preferably 5% or more higher than the absorbance before the treatment (initial absorbance) is used as the first transparent protective film. Can be done. The increase in the absorbance after the above treatment with respect to the initial absorbance may be 10% or more, or 15% or more, from the viewpoint of expanding the selection range for the material of the first transparent protective film. Further, the increase in the absorbance after the above treatment with respect to the initial absorbance is usually 25% or less.

If necessary, the polarizing plate of the present invention may be further laminated with optical layers such as a retardation film, a viewing angle compensation film, and a brightness improving film. In the polarizing plate of the present invention, the optical layer can be formed by using a material known in the art.

The polarizing plate of the present invention can be produced by a known method. For example, a curable composition is applied to a transparent protective film to form a second curable composition layer, and a polarizing film is attached to the second curable composition layer to prepare a laminate. In the case of a polarizing plate that does not contain the first transparent protective film, a curable composition is applied onto the release film to form a first curable composition layer, and the polarizing film side of the laminate is bonded to the coated surface. To do. Next, the second curable composition layer and the first curable composition layer are cured by irradiating with active energy rays such as ultraviolet rays and electron beams to form the second cured product layer and the first cured product layer. , The release film may be peeled off to form an adhesive layer on the first curable composition layer. On the other hand, in the case of a polarizing plate containing the first transparent protective film, a curable composition is applied onto the transparent protective film to form a first cured product layer, and the polarizing film side of the laminate is bonded to the coated surface. After that, the first cured product layer may be formed by irradiating with active energy rays such as ultraviolet rays and electron beams, and then an adhesive layer may be formed on the first transparent protective film.

The polarizing plate of the present invention can be used as a polarizing plate for an image display panel such as a liquid crystal panel or an organic EL panel. In the present invention, the polarizing plate can suppress a decrease in optical performance even when used in a high temperature and high humidity environment and / or for a long period of time, and therefore can be suitably used as a polarizing plate for an image display panel. The image display device provided with the polarizing plate of the present invention is less likely to cause a problem in image display performance.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Unless otherwise specified, "%" and "part" in Examples and Comparative Examples represent "% by mass" and "part by mass", respectively.

1. 1. Preparation of Laminate A The polymerizable compounds (a-1), (a-2), (a-3) and (a-4) shown below and the photocationic polymerization initiator (b-1) are mixed to prepare the laminate A. A curable composition a was prepared.
(A-1) 3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate 25 parts by mass (a-2) Neopentyldiglycidyl ether 55 parts by mass (a-3) Glycidyl methacrylate 25 parts, Methyl methacrylate 75 Polymer with a weight average molecular weight of 15,000 obtained by radically polymerizing a monomer composed of parts (GMA-PMMA (polymethyl methacrylate) copolymer) 15 parts by mass (a-4) Hydroxybutyl vinyl ether 5 parts by mass (b-1) Triarylsulfonium hexafluorophosphate 2.25 parts by mass

Acrylic resin (PMMA) film with a thickness of 60 μm containing an ultraviolet absorber [trade name “Technoloy S001”, manufactured by Sumitomo Chemical Co., Ltd.] (second transparent protective film) is subjected to corona discharge treatment, and the corona discharge treatment is performed. The curable composition a was applied to the surface using a bar coater so that the film thickness after curing was about 3 μm to form a layer of the curable composition a. A polyvinyl alcohol (PVA) -iodine-based polarizing film having a thickness of 25 μm was laminated on this layer to prepare a laminate. Ultraviolet rays are emitted from the polarizing film side of this laminate using an ultraviolet irradiation device with a belt conveyor [lamp: "D valve" manufactured by Fusion UV Systems Co., Ltd.] so that the integrated light amount having a wavelength of 280 nm to 320 nm is 200 mJ / cm ^2. By irradiating, the curable composition a was cured to prepare a laminate A composed of an acrylic resin film (second transparent protective film) / second cured product layer / polarizing film.

2. 2. Preparation of Adhesive Composition The acrylic adhesive was prepared as follows.
To 70.4 parts by mass of butyl acrylate, 20.0 parts by mass of methyl acrylate, 0.6 parts by mass of acrylic acid, 8.0 parts by mass of 2-phenoxyethyl acrylate and 1.0 part by mass of 2-hydroxyethyl acrylate. On the other hand, azobisisobutyronitrile 0.14, which is a polymerization initiator, was added and a polymerization reaction was carried out to prepare an acrylic resin. An isocyanate-based cross-linking agent (Coronate L: Trimethylolpropane adduct of tolylene diisocyanate, ethyl acetate solution (solid content concentration: 75%), manufactured by Nippon Polyurethane Co., Ltd., based on 20.0 parts by mass of the solid content of the acrylic resin. ) 0.45 parts by mass, silane coupling agent (KBM-403: 3-glycidoxypropyltrimethoxysilane (liquid), manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 0.45 parts by mass, and antistatic agent (1- Hexylpyridinium hexafluorophosphate (a compound represented by the following formula (f)) was added in an amount of 3.0 parts by mass to prepare an organic solvent solution of an acrylic resin pressure-sensitive adhesive.

[Example 1]
First, each polymerizable compound shown in Table 1 and a photocationic polymerization initiator (b-1) were mixed in each amount used to prepare a curable composition b. Next, one surface of a cellulosic transparent protective film [Fuji Film Co., Ltd. "ZRE34"] having a thickness of 34 μm was subjected to corona discharge treatment, and the curable composition b was applied to the surface after curing using a bar coater. The coating was applied so that the film thickness was about 3 μm. The laminate A was bonded to the polarizing film side on the coated surface to prepare a laminate. From the cellulose-based transparent protective film side of this laminate, an ultraviolet irradiation device with a belt conveyor [lamp: "D valve" manufactured by Fusion UV Systems Co., Ltd.] is used so that the integrated light amount at a wavelength of 280 nm to 320 nm becomes 200 mJ / cm ^2. Was irradiated with ultraviolet rays to cure the curable composition b. In this way, a laminate B composed of an acrylic resin film (second transparent protective film) / second cured product layer / polarizing film / first cured product layer / cellulose-based transparent protective film (first transparent protective film) was produced.

A 38 μm-thick polyethylene terephthalate film [trade name “SP-PLR382050”, manufactured by Lintec Co., Ltd. (hereinafter referred to as “release film”)] obtained by subjecting the organic solvent solution of the acrylic resin adhesive to a mold release treatment. The release-treated surface was coated with a die coater so that the thickness after drying was 20 μm, and dried to prepare a sheet-like adhesive with a release film. Then, a surface (adhesive surface) opposite to the release film side of the sheet-like adhesive is bonded to the cellulose-based transparent protective film (first transparent protective film) side of the laminate B with a laminator, and then the temperature is adjusted. The film was cured at 23 ° C. and a relative humidity of 65% for 7 days to obtain a polarizing plate (1) provided with an adhesive layer. This polarizing plate has a structure in which a release film is laminated on an adhesive layer.

Durability evaluation The obtained polarizing plate (1) is cut into a size of 30 mm × 30 mm, the release film is peeled off, and the adhesive layer side thereof is bonded to non-alkali glass [trade name “EAGLE XG” manufactured by Corning Inc.]. did. The durability of the obtained sample was evaluated as follows.

The sample was autoclaved at a temperature of 50 ° C. and a pressure of 5 kg / cm ² (490.3 kPa) for 1 hour, and then held at a temperature of 23 ° C. and a relative humidity of 55% for 24 hours. For this sample, an optional accessory "film holder with polarizing film" was set on an ultraviolet visible spectrophotometer (UV2450, manufactured by Shimadzu Corporation), and the transmission axis direction and absorption of the polarizing plate in the wavelength range of 380 to 700 nm. The transmission spectra in the axial direction were measured, and the degree of polarization Py (unit:%) was determined based on them. The degree of polarization in this state was defined as the degree of initial polarization (Py after the test). Then, the degree of polarization (initial Py) after the test was determined in the same manner as above for the sample after standing at 85 ° C. in an environment with a relative humidity of 85% for 12 hours. The degree of polarization change ΔPy was calculated from the following formula with the optical performance in the state before being allowed to stand in an environment of 85 ° C. and a relative humidity of 85% for 12 hours as an initial value. The results are shown in Table 1.
ΔPy = post-test Py-initial Py

The absorbance of the cellulosic transparent protective film [trade name "ZRE34" manufactured by Fuji Film Co., Ltd.] with respect to light having a wavelength of 360 nm was measured using an ultraviolet-visible spectrophotometer [Shimadzu Corporation "UV2450"]. , The absorbance was taken as the initial absorbance. Next, this film was immersed in a 50 mass% potassium iodide aqueous solution in an air atmosphere of 23 ° C. and 60% RH for 4.5 hours, taken out, washed with water at 23 ° C. in the air, and placed in a dark place at 23 ° C. in the air. Was dried for 15 hours. When the absorbance of the film after this treatment with respect to light having a wavelength of 360 nm was measured, it was found to be 22% higher than the initial absorbance.

[Examples 2 to 10]
An acrylic resin film (No. 1) in the same manner as in Example 1 except that a curable composition prepared by mixing each compound shown in Table 1 in each amount used was used instead of the curable composition b. A laminate composed of (2 transparent protective film) / second cured product layer / polarizing film / first cured product layer / cellulose-based transparent protective film (first transparent protective film) was produced.

Next, an adhesive layer was provided in the same manner as in Example 1, and polarizing plates (2) to (10) were obtained, respectively. Durability was evaluated for each of the polarizing plates (2) to (10). The results are shown in Table 1.

[Comparative Example 1]
The polarizing plate (11) was prepared in the same manner as in Example 1 except that the compounds shown in Table 1 were mixed in each amount to prepare a curable composition d and applied to a cellulosic transparent protective film. Got The durability of this polarizing plate (11) was evaluated. The results are shown in Table 1.

[Comparative Examples 2 to 7]
The polarizing plate (12) was prepared in the same manner as in Example 1 except that the compounds shown in Table 1 were mixed in each amount to prepare a curable composition e and applied to a cellulosic transparent protective film. ~ (17) was obtained. Durability evaluation was performed for each of the polarizing plates (12) to (17). The results are shown in Table 1.

The compounds in Table 1 are as follows.
-Oxetane compound (bifunctional): Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd.)
Aliphatic epoxy compound (1): 1,4-butanediol diglycidyl ether (EX214, Nagase ChemteX Corporation)
-Alphatic epoxy compound (2): 1,6-hexanediol diglycidyl ether (EX212, Nagase ChemteX Corporation)
Aliphatic epoxy compound (3): Neopentyl glycol diglycidyl ether (EX211, Nagase ChemteX Corporation)
-Alphatic epoxy compound (4): Cyclohexanedimethanol diglycidyl ether (EX216, Nagase ChemteX Corporation)
-Alphatic epoxy compound (5): Pentaerythritol polyglycidyl ether (EX411, Nagase ChemteX Corporation)
-Alicyclic epoxy compound: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (CEL2021P, Daicel Chemical Co., Ltd.)
Aromatic epoxy compound (1): 2- [4- (2,3-epoxypropoxy) phenyl] -2- [4- [1,1-bis [4-([2,3-epoxypropoxy] phenyl] Ethyl] Phenyl] Propane (TECHMORE VG3101L, Printec Co., Ltd.)
-Aromatic epoxy compound (2): Resolcinol diglycidyl ether (EX-201, Nagase ChemteX Corporation)
-Aromatic epoxy compound (3): Bis F type epoxy (jER806, Mitsubishi Chemical Corporation)
-Aromatic epoxy compound (4): p-tert-butylphenylglycidyl ether (EX-146, Nagase ChemteX Corporation)
-Aliphatic epoxy compound: 2-ethylhexyl glycidyl ether (EX121, Nagase ChemteX Corporation)
-Oxetane compound (monofunctional): 3-ethyl-3-hydroxymethyloxetane (OXT101, Toagosei Co., Ltd.)
Photocationic polymerization initiator (b-1): triarylsulfonium hexafluorophosphate

From Table 1, it can be seen that the polarizing plates (1) to (10) obtained in Examples 1 to 10 have a small change in degree of polarization ΔPy, so that there is no significant change in optical performance and high durability is exhibited. On the other hand, in all of the polarizing plates (11) to (17) obtained in Comparative Examples 1 to 7, the degree of polarization change ΔPy was large, and a decrease in optical performance was observed.

1: Polarizing film 2: First cured product layer 3: Adhesive layer 4: Second cured product layer 5: Second transparent protective film 6: First transparent protective film 10: Polarizing plate X: Liquid crystal cell

Claims (4)

One surface of a polarizing film containing a dichroic dye in a polyvinyl alcohol-based resin contains a first cured product layer composed of a cured product of a curable composition containing a polymerizable compound, and an ionic compound. A polarizing plate containing an adhesive layer in this order, wherein the curable composition is based on 100% by mass of the total amount of the polymerizable compound.
(A1) Oxetane compound having two or more oxetanyl groups 15 to 60% by mass,
(A2) Aliphatic epoxy compound having two or more epoxy groups 3 to 40% by mass ,
(A4-1) 30 to 60% by mass of an alicyclic epoxy compound having two or more epoxy groups , and
(A4-2) Aromatic epoxy compound having two or more epoxy groups 0.1 to 20% by mass
Contains,
A polarizing plate in which the content of the oxetane compound (A3) having one oxetanyl group is 10% by mass or less based on 100% by mass of the total amount of the polymerizable compound. The content of aliphatic epoxy compounds having a contact Keru (A2) 2 or more epoxy groups in the curable composition is 3 to 25 wt% based on 100 mass% of the polymerizable compound, to claim 1 The polarizing plate according to the description. A first transparent protective film is provided between the first cured product layer and the adhesive layer, and the first transparent protective film is prepared in a 50 mass% potassium iodide aqueous solution in an air atmosphere of 23 ° C. and 60% RH. .The absorbance for light with a wavelength of 360 nm after the treatment of immersion for 5 hours, removal, washing with water at 23 ° C. in the air for 15 seconds, and drying in a dark place at 23 ° C. in the air for 15 hours is the absorbance before the treatment. The polarizing plate according to claim 1 or 2 , which is 5% or more higher than that of the polarizing plate. The polarizing plate according to any one of claims 1 to 3 , wherein a second transparent protective film is provided on a surface of the polarizing film opposite to the first cured product layer side via a second cured product layer.

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