KR101667056B1 - A liquid crystal panel - Google Patents

Abstract

The first polarizing plate 21 is adhered to one surface of the liquid crystal cell 10 through the first pressure sensitive adhesive layer 31 so that the absorption axis 21A is parallel to the long side 10A of the liquid crystal cell, The second polarizing plate 22 is adhered to the other side of the liquid crystal panel 22 through the second pressure sensitive adhesive layer 32 so that the absorption axis 22A is orthogonal to the absorption axis 21A of the first polarizing plate. At least one of the pressure-sensitive adhesive layers 31 and 32 is prepared by copolymerizing 80 to 96% by weight of alkyl (meth) acrylate, 3 to 15% by weight of an aromatic ring-containing monomer and 0.1 to 5% by weight of a polar functional group- (B) is contained in 100 parts by weight of an acrylic resin (A) having a molecular weight of from 1 to 200,000 and a molecular weight distribution of 3 to 7, and the gel fraction of the pressure-sensitive adhesive layer is from 60 to 99 wt% %. In the liquid crystal panel of the present invention, a pair of polarizing plates are adhered to both surfaces of the liquid crystal cell through a pressure-sensitive adhesive layer, respectively, so that whiteout can be suppressed even if the polarizing plate is enlarged.

Description

A liquid crystal panel {A LIQUID CRYSTAL PANEL}

The present invention relates to a liquid crystal panel in which a polarizing plate is bonded to both surfaces of a glass cell for liquid crystal display through a pressure-sensitive adhesive layer.

A polarizing plate is widely used in a liquid crystal display and is widely used. A transparent protective film is laminated on both sides of a polarizing film, and a pressure-sensitive adhesive layer is formed on the surface of at least one protective film. It is circulating. There is also a case where a retardation film is laminated on a polarizing plate in which a protective film is adhered to both surfaces of a polarizing film, and the pressure-sensitive adhesive layer / release film is adhered to the retardation film side. Prior to adhering to the liquid crystal cell, the release film is peeled off from these polarizing plates and adhered to the glass cell for liquid crystal display through the exposed pressure-sensitive adhesive layer to form a liquid crystal panel, and backlight or the like is set to form a liquid crystal display device. When the liquid crystal panel in which the polarizing plate is adhered to the liquid crystal display glass cell is exposed to high temperature, the distribution of residual stress acting on the polarizing plate becomes uneven and stress concentration occurs in the outer peripheral portion of the polarizing plate. As a result, (Sometimes referred to as " light leakage ") called whiteout in which the outer peripheral portion is exposed to white light in some cases, or may cause color unevenness. Therefore, suppression of such whiteout or color unevenness is required.

JP-2007-138056-A discloses a method in which a ratio of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of a resin obtained by copolymerizing an aromatic ring-containing monomer with an alkyl acrylate ester (Mw / Mn ) To 10 to 50, thereby suppressing light leakage. By using such a pressure-sensitive adhesive, light leakage is alleviated, but it can not be said to be necessarily sufficient, and since the molecular weight distribution is wide, foaming may occur under high temperature conditions.

On the other hand, in the case where the liquid crystal panel is subjected to high temperature or high temperature and high humidity conditions or repeated heating and cooling, the liquid crystal panel may cause foaming of the pressure-sensitive adhesive layer in accordance with the dimensional change of the polarizing plate, There is a possibility that floating or peeling may occur. Therefore, it is required to have excellent durability without causing such a problem. Further, when a polarizing plate having a pressure-sensitive adhesive is adhered to a glass cell for liquid crystal display to form a liquid crystal panel, if there is any problem, the polarizing plate is once peeled off and then the new film is stuck again. It is required to be excellent in so-called reworkability, in which the pressure-sensitive adhesive is not left on the glass cell and dark portions are not formed, such as pulled off by the polarizing plate.

JP-2010-66756-A discloses an acrylic resin obtained by copolymerizing a (meth) acrylic acid alkyl ester represented by butyl acrylate as a typical example with a (meth) acrylic acid alkoxyalkyl ester represented by 2-methoxyethyl acrylate , And an ionic compound, in particular, an ionic compound which is solid at room temperature to form a pressure-sensitive adhesive layer. By providing the pressure-sensitive adhesive layer on the optical film, it is possible to provide an antistatic property excellent in antistatic property, .

An object of the present invention is to provide a liquid crystal panel in which a pair of polarizing plates are adhered to both surfaces of a glass cell for liquid crystal display through a pressure-sensitive adhesive layer, thereby sufficiently suppressing whiteout even if the polarizing plate is enlarged.

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted intensive studies to solve these problems and found that a first polarizing plate and a second polarizing plate are respectively adhered to both sides of a glass cell for liquid crystal display having a rectangular display screen through a pressure- The absorption axis of which is parallel to the long side of the glass cell and the absorption axis of the second polarizing plate is orthogonal to the absorption axis of the first polarizing plate. In the liquid crystal panel for use in a large-sized liquid crystal display device, It has been found out that the whiteout can be effectively suppressed by improving the layer, and a liquid crystal panel having excellent durability can be obtained, and that the pressure-sensitive adhesive layer is also excellent in lithheet workability of the polarizing plate. Concretely, the pressure-sensitive adhesive layer is composed of a structural unit derived from an unsaturated monomer having a polar functional group and having a (meth) acrylic acid alkyl ester as a main component, and a structural unit derived from an unsaturated monomer having an aromatic ring in the molecule It has been found out that it is effective to constitute a composition comprising a predetermined amount of a crosslinking agent in an acrylic resin having a narrow molecular weight distribution, including a predetermined amount.

That is, the liquid crystal panel according to the present invention comprises a glass cell for a liquid crystal display having a rectangular shape, and a first adhesive layer on one side of the glass cell, wherein the absorption axis is adhered so as to be parallel to long sides of the glass cell And a second polarizing plate adhered to the other surface of the glass cell through a second pressure sensitive adhesive layer so that an absorption axis thereof is orthogonal to an absorption axis of the first polarizing plate, wherein the first pressure sensitive adhesive layer and the second pressure sensitive adhesive layer 2 pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition containing an acrylic resin (A) and a crosslinking agent (B) shown below, and the pressure-sensitive adhesive layer has a gel fraction of 60 to 99 wt%.

(A) (A-1)

(Wherein 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)

80 to 96% by weight of (meth) acrylic acid alkyl ester,

(A-2) 3 to 15% by weight of an unsaturated monomer having one olefinic double bond and one or more aromatic rings in the molecule (hereinafter sometimes referred to as " aromatic ring-containing monomer &

(A-3) 0.1-5 wt% of an unsaturated monomer having a polar functional group (hereinafter sometimes referred to as " polar functional group-containing monomer "

(Mw), which is a ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) in the range of from 1 million to 200,000 and which is obtained by copolymerizing a monomer mixture 100 parts by weight of an acrylic resin having a distribution in the range of 3 to 7, and

(B) 0.01 to 5 parts by weight of a crosslinking agent.

As described above, in the present invention, at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer for adhering the first polarizing plate and the second polarizing plate disposed on both surfaces of the glass cell for liquid crystal display to the glass cell, (A) obtained by copolymerization of a monomer mixture comprising a (meth) acrylic acid alkyl ester (A-1), an aromatic ring-containing monomer (A-2) and a polar functional group- And a cross-linking agent (B). Further, by setting the gel fraction to a predetermined range, the whiteout can be effectively suppressed.

[2] The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are all formed of a pressure-sensitive adhesive composition containing 100 parts by weight of the acrylic resin (A) and 0.01 to 5 parts by weight of the crosslinking agent (B) The liquid crystal panel according to [1], wherein the liquid fraction has a gel fraction of 99% by weight. This mode is even more preferable in suppressing whiteout.

[3] The liquid crystal panel according to [1] or [2], wherein the aromatic ring-containing monomer (A-2) is an aromatic ring-containing (meth) acrylic compound represented by the following formula II. This embodiment is preferable.

In the formula, R ₃ represents a hydrogen atom or a methyl group, n represents an integer of 1 to 8, and R ₄ represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group.

[4] The polar functional group-containing monomer (A-3) according to any one of [1] to [3], wherein the polar functional group-containing monomer (A-3) has at least one polar functional group selected from the group consisting of free carboxyl group, hydroxyl group, amino group, Liquid crystal panel. This embodiment is preferable.

[5] The liquid crystal panel according to any one of [1] to [4], wherein the crosslinking agent (B) contains an isocyanate compound. This embodiment is preferable.

[6] The liquid crystal panel according to [4], wherein the cross-linking agent (B) contains at least an isocyanate-based compound. This embodiment is preferable.

[7] The liquid crystal panel according to any one of [1] to [6], wherein the pressure-sensitive adhesive composition further comprises 0.03 to 1 part by weight of the silane compound (C).

[8] The liquid crystal panel according to any one of [1] to [7], wherein the pressure-sensitive adhesive composition further comprises (D) an ionic compound. The antistatic property can be imparted by this aspect.

[9] The liquid crystal panel according to [8], wherein the aromatic ring-containing monomer (A-2) is an aromatic ring-containing (meth) acrylic compound represented by the formula II and n is 2 or more. In the case of this embodiment, the ionic compound is added to the pressure-sensitive adhesive composition comprising the acrylic resin copolymerized with the monomer, which is more effective in suppressing the whiteout, and the antistatic property is imparted I know that I can do it.

[10] The liquid crystal panel according to any one of [1] to [9], wherein at least one of the first polarizing plate and the second polarizing plate is a protective film / polarizing film / protective film. This embodiment is preferable.

[11] Among the two protective films sandwiching the polarizing film therebetween, the film located farther from the glass cell for liquid crystal display has an in-plane retardation value of 0 to 20 nm and a retardation value in the thickness direction of 20 to 80 nm The cellulose acylate film according to any one of [10] to [10], wherein the film comprises a cellulose resin and the cellulose acylate resin has a retardation value in a plane of 30 to 80 nm and a retardation value in a thickness direction of 80 to 250 nm A liquid crystal panel as claimed. This embodiment is preferable.

[12] Among the two protective films sandwiching the polarizing film therebetween, the film located on the far side from the glass cell for liquid crystal display has an in-plane retardation value of 0 to 20 nm and a retardation value in the thickness direction of 20 to 80 nm A cellulose acetate resin and a cellulose acylate resin having a retardation value in the plane of 0 to 10 nm and a retardation value in the thickness direction of -25 to 25 nm, And a liquid crystal panel. This aspect is also preferable.

[13] Among the two protective films sandwiching the polarizing film therebetween, the film located farther from the glass cell for liquid crystal display comprises a cellulose acetate resin, and the film located on the glass cell side for liquid crystal display is a cycloolefin resin The liquid crystal panel according to [10], further comprising: This aspect is also preferable.

In the present invention, a pair of polarizing plates is adhered to both sides of a glass cell for liquid crystal display through cross-linked adhesive layers so as to crossed nicols, that is, each absorption axis is orthogonal, and one polarizing plate absorbs Wherein the acrylic resin (A) for forming the pressure-sensitive adhesive layer contains a predetermined amount of units derived from the aromatic ring-containing monomer (A-2) By making the copolymer a weight average molecular weight (Mw) and a molecular weight distribution (Mw / Mn) within a specific range, optical defects due to uneven stress distribution are prevented, and whiteout is suppressed.

In addition, the durability of the pressure-sensitive adhesive layer is improved by setting the gel fraction of the pressure-sensitive adhesive layer in the range of 60 to 99 wt%, whereby the appearance of the liquid-crystal panel is suppressed when tested for heat resistance, wet heat resistance, . Further, in the case where the polarizing plate is adhered to the glass cell for liquid crystal display through the above-mentioned pressure-sensitive adhesive layer, the liquid crystal panel can be peeled off from the glass cell together with the pressure- Adhesive residue or dark portion is less likely to occur, and the reworkability is excellent.

In this liquid crystal panel, since the pressure-sensitive adhesive layer absorbs and alleviates the stress caused by the dimensional change of the polarizing plate and the glass cell under the moist heat condition, the local stress concentration is alleviated and the pressure sensitive adhesive layer is prevented from being lifted or peeled off from the glass cell do.

1 is an exploded perspective view showing the relationship between the layer structure and the axial angle of the liquid crystal panel according to the present invention.
2 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate having a pressure-sensitive adhesive layer for adhering to a glass cell for liquid crystal display.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings appropriately. Fig. 1 is an exploded perspective view showing the relationship between the layer structure and the axis angle of the liquid crystal panel according to the present invention. 1, a liquid crystal panel to which the present invention is applied includes a liquid crystal display glass cell 10 (hereinafter, simply referred to as a " liquid crystal cell " or a " glass cell " The first polarizing plate 21 is adhered to the one side of the liquid crystal cell 10 through the first pressure sensitive adhesive layer 31 and the second polarizing plate 22 is bonded to the other side of the liquid crystal cell 10 through the second pressure sensitive adhesive layer 32. [ . The absorption axes 21A and 22A of the pair of polarizers 21 and 22 are orthogonal to each other so that the absorption axes 21A and 22A of the first polarizers 21 and 22 are perpendicular to each other. 10 parallel to the long side 10A of the first housing 10A. The second polarizing plate 22 is arranged so that the absorption axis 22A thereof is perpendicular to the long side 10A of the liquid crystal cell 10 (parallel to the short side of the liquid crystal cell 10).

At least one of the first pressure sensitive adhesive layer 31 for adhering the first polarizing plate 21 to the liquid crystal cell 10 and the second pressure sensitive adhesive layer 32 for adhering the second polarizing plate 22 to the liquid crystal cell 10 Is formed from a pressure-sensitive adhesive composition containing 0.01 to 5 parts by weight of a crosslinking agent (B) relative to 100 parts by weight of a specific acrylic resin (A), and the gel fraction of the pressure-sensitive adhesive layer is made 60 to 99% by weight.

The first polarizing plate 21 is arranged such that its absorption axis 21A is parallel to the long side 10A of the liquid crystal cell 10 and the second polarizing plate 22 is disposed so as to be parallel to the absorption axis 22A. It is particularly effective to apply a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition defined in the present invention to a liquid crystal panel arranged so as to be perpendicular (90 DEG) to the long side 10A of the liquid crystal cell 10. The desired effect can be obtained by forming at least one of the pressure-sensitive adhesive layers 31 and 32 disposed on both sides of the liquid crystal cell 10 with the specific pressure-sensitive adhesive composition described above and setting the gel fraction to a specific range, As described above, it is preferable to configure both of the pressure-sensitive adhesive layers 31 and 32 disposed on both surfaces of the liquid crystal cell 10 from the viewpoint of suppressing the whiteout.

Hereinafter, the liquid crystal display glass cells 10 are sequentially described with respect to each member constituting the liquid crystal panel of the present invention.

[Glass cell for liquid crystal display]

The liquid crystal display glass cell 10 is composed of two transparent glass substrates 11 and 12 and a liquid crystal (not shown) sandwiched therebetween. The liquid crystal sealed between the two glass substrates 11 and 12 may be twisted nematic (TN), vertical alignment (VA), in-plane switching (IPS) And the like. The present invention can be applied to any type of liquid crystal cell insofar as the pair of polarizing plates are arranged on the upper and lower sides of the liquid crystal cell in orthogonal Nicols and the absorption axis of one of the polarizing plates is arranged in parallel with the longer side of the glass cell have. Although not shown, on the liquid crystal layer side of the transparent glass substrates 11 and 12, an alignment film for aligning the liquid crystal, a transparent electrode for turning on and off the voltage to control the alignment, and a color filter for color display are arranged.

Soda lime glass, low alkali glass, alkali-free glass, or the like can be applied to the glass substrates 11 and 12 constituting the liquid crystal cell 10, and in particular, alkali-free glass or low alkali glass is suitably used.

[Pressure sensitive adhesive layer (pressure sensitive adhesive composition)]

Next, the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layers 31 and 32 will be described. This pressure-sensitive adhesive composition basically comprises an acrylic resin and a crosslinking agent. In the present invention, at least one of the first pressure sensitive adhesive layer (31) for adhering the first polarizing plate and the second pressure sensitive adhesive layer (32) for adhering the second polarizing plate on both sides of the liquid crystal cell (10) (A) having a specific weight average molecular weight (Mw) and a molecular weight distribution (Mw / Mn) in a predetermined range and a crosslinking agent (B) in a predetermined amount, and the pressure- So that the gel fraction is 60 to 99% by weight. Each component constituting this pressure-sensitive adhesive composition will be described.

≪ Acrylic resin (A) >

In the liquid crystal panel of the present invention, the acrylic resin (A) used in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layers (31, 32) has a structural unit derived from the (meth) acrylic acid alkyl ester represented by the above formula , And includes a structural unit derived from an aromatic ring-containing monomer and a structural unit derived from a polar functional group-containing monomer, in addition to a structural unit derived from such a (meth) acrylic acid alkyl ester. Here, (meth) acrylic acid means either acrylic acid or methacrylic acid, and "(meth)" when referring to (meth) acrylate or (meth) acryloyl is also the same .

In formula (I), which is a main structural unit of the acrylic resin (A), R ₁ is a hydrogen atom or a methyl group, and R ₂ is an alkyl group having 1 to 14 carbon atoms. The alkyl group represented by R ₂ may be substituted by an alkoxy group having 1 to 10 carbon atoms in each group.

Specific examples of the alkyl (meth) acrylate ester (A-1) represented by the formula (I) wherein R ₂ is an unsubstituted alkyl group include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, Linear alkyl acrylate esters such as lauryl; Branched acrylic acid alkyl esters such as isobutyl acrylate, 2-ethylhexyl acrylate and isooctyl acrylate; Linear methacrylic alkyl esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate and lauryl methacrylate; Methacrylic acid alkyl esters such as isobutyl methacrylate, 2-ethylhexyl methacrylate and dioctyl methacrylate are exemplified.

Of these, n-butyl acrylate is preferable, and specifically, among the total monomers constituting the acrylic resin (A), the proportion of the (meth) acrylic acid alkyl ester (A-1 ) Is satisfied.

Specific examples of the (meth) acrylic acid alkyl ester represented by the formula (I) in which R ₂ is an alkyl group substituted with an alkoxy group, that is, an alkoxyalkyl group include 2-methoxyethyl acrylate, ethoxymethyl acrylate, 2- Methoxyethyl, ethoxyethyl, ethoxymethyl methacrylate, and the like.

These (meth) acrylic acid alkyl esters may be copolymerized using a plurality of other than those which can be used alone.

The unsaturated monomer (aromatic ring-containing monomer) (A-2) having one olefinic double bond and at least one aromatic ring in the molecule preferably has a (meth) acryloyl group as a group containing an olefinic double bond Do. Examples thereof include benzyl (meth) acrylate, neopentyl glycol benzoate (meth) acrylate and the like. Preferred is an aromatic ring-containing (meth) acrylic compound represented by the formula II.

In the formula (II) representing an aromatic ring-containing (meth) acrylic compound, when R ₄ is an alkyl group, the number of carbon atoms thereof may be about 1 to 9, and when it is an aralkyl group, its carbon number is about 7 to 11, , The carbon number thereof may be about 6 to 10. Benzyl, phenethyl, naphthylmethyl and the like as an aralkyl group having 7 to 11 carbon atoms and phenyl, tolyl, naphthyl and the like as an aryl group having 6 to 10 carbon atoms as the alkyl group having 1 to 9 carbon atoms, Respectively.

Specific examples of the aromatic ring-containing (meth) acrylic compound of the formula (II) include 2-phenoxyethyl (meth) acrylate, 2- (2-phenoxyethoxy) ethyl Esters, and 2- (o-phenylphenoxy) ethyl (meth) acrylate. These aromatic ring-containing monomers may be used alone or in combination of two or more. Among these, a (meth) acrylate, 2-phenoxyethyl [In the formula II, R ₄ = H, the compound of n = 1], (meth) acrylate, 2- (o- phenyl phenoxy) acetate [the formula II according, R ₄ = phenyl o-, a compound of n = 1], or a (meth) acrylate, 2 in the (2-phenoxy) ethyl [the formula II, R ₄ = H, the compound of n = 2] Is suitably used as one of the aromatic ring-containing monomer (A-2) constituting the acrylic resin (A).

In the polar functional group-containing monomer (A-3), the polar functional group may be a free carboxyl group, a hydroxyl group, an amino group, a heterocyclic group including an epoxy ring, and the like. The polar functional group-containing monomer is preferably a (meth) acrylic acid-based compound having a polar functional group. Examples thereof include unsaturated monomers having a free carboxyl group such as acrylic acid, methacrylic acid and? -Carboxyethyl acrylate; Such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- or 3-chloro-2-hydroxypropyl (meth) acrylate and diethylene glycol mono (meth) (Meth) acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexyl (meth) acrylate, Unsaturated monomers having a heterocyclic group such as hexyl methyl (meth) acrylate, glycidyl (meth) acrylate and 2,5-dihydrofuran; And unsaturated monomers having an amino group different from the heterocyclic ring, such as N, N-dimethylaminoethyl (meth) acrylate.

The polar functional group is preferably a free carboxyl group, a hydroxyl group, an amino group or an epoxy group. These polar functional group-containing monomers may be used alone or in a plurality of different polar functional group-containing monomers.

Among them, it is preferable to use the unsaturated monomer having a hydroxyl group as one of the polar functional group-containing monomers (A-3) constituting the acrylic resin (A). It is also effective to use, in addition to the unsaturated monomer having a hydroxyl group, an unsaturated monomer having another polar functional group, for example, an unsaturated monomer having a free carboxyl group.

In the acrylic resin (A), the structural unit derived from the (meth) acrylic acid alkyl ester (A-1) represented by the above formula I is 80 to 96% by weight, preferably 82% Preferably not more than 94% by weight. The content of the structural unit derived from the aromatic ring-containing monomer (A-2) is 3 to 15% by weight, preferably 5% by weight or more, more preferably 7% by weight or more, 13% by weight or less, more preferably 11% by weight or less, especially 10% by weight or less. The structural unit derived from the polar functional group-containing monomer (A-3) is 0.1 to 5% by weight, preferably 0.5% by weight or more, and more preferably 3% by weight or less.

The acrylic resin (A) used in the present invention is a copolymer of the alkyl (meth) acrylate (A-1), the aromatic ring-containing monomer (A-2) and the polar functional group- May contain a structural unit derived from a monomer different from the monomer. Examples thereof include a structural unit derived from a (meth) acrylic acid ester having an alicyclic structure in the molecule, a structural unit derived from a styrene monomer, a structural unit derived from a vinyl monomer, a plurality of (meth) acryloyl groups And a structural unit derived from a monomer having a carboxyl group.

The alicyclic structure is a cycloparaffin structure having a ring-forming carbon number of usually 5 or more, preferably 5 to 7 or so. Specific examples of the acrylic ester having an alicyclic structure include acrylic acid esters such as isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, tert-butylcyclohexyl acrylate, Cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate and cyclohexyl phenyl acrylate. Methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, cyclohexylphenyl methacrylate, and the like can be given.

Specific examples of the styrene-based monomer include, in addition to styrene, alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene and octylstyrene; Halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene and iodostyrene; Further, nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene and the like can be given.

Specific examples of the vinyl monomer include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate and vinyl laurate; Vinyl halides such as vinyl chloride and vinyl bromide; 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; Further, acrylonitrile, methacrylonitrile 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. Acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and tripropylene glycol di (meth) acrylate, ethylene glycol di A monomer having two (meth) acryloyl groups in the molecule such as a carboxyl group; And monomers having three (meth) acryloyl groups in the molecule such as trimethylolpropane tri (meth) acrylate.

The monomers other than the alkyl (meth) acrylate (A-1), the aromatic ring-containing monomer (A-2) and the polar functional group-containing monomer (A-3) represented by the above formula These can be used in combination. A structure derived from a monomer other than the (meth) acrylic acid alkyl ester (A-1), the aromatic ring containing monomer (A-2) and the polar functional group containing monomer (A-3) in the acrylic resin (A) The unit is usually contained in an amount of 0 to 10 parts by weight based on 100 parts by weight of the nonvolatile matter of the resin.

The resin component constituting the pressure-sensitive adhesive composition is preferably a resin component comprising the (meth) acrylic acid alkyl ester (A-1), the aromatic ring-containing monomer (A-2) and the polar functional group- Or two or more kinds of acrylic resins including structural units. The acrylic resin (A) specified in the present invention is mixed with an acrylic resin different from the acrylic resin, for example, an acrylic resin having a structural unit derived from a (meth) acrylic acid alkyl ester of formula (I) . The acrylic resin (A) comprising a structural unit derived from a (meth) acrylic acid alkyl ester (A-1), an aromatic ring-containing monomer (A-2) and a polar functional group- And 80% by weight or more, and more preferably 90% by weight or more, of the entire acrylic resin.

(A) obtained by copolymerizing a monomer mixture comprising a (meth) acrylic acid alkyl ester (A-1), an aromatic ring-containing monomer (A-2) and a polar functional group-containing monomer (A- Has a weight average molecular weight (Mw) in terms of standard polystyrene by gel permeation chromatography (GPC) in the range of 1,000,000 to 2,000,000. When the weight average molecular weight in terms of standard polystyrene is more than 1,000,000, the adhesiveness under high temperature and high humidity is improved and the possibility of floating or peeling between the liquid crystal cell and the pressure-sensitive adhesive layer tends to be lowered. . If the weight average molecular weight is not more than 2,000,000, even if the size of the polarizing plate adhered to the pressure-sensitive adhesive layer changes, the pressure-sensitive adhesive layer follows and changes in accordance with the dimensional change. Therefore, a difference between the brightness of the periphery of the liquid- Disappear, and whiteout and color unevenness tend to be suppressed.

The molecular weight distribution represented by Mw / Mn, which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is in the range of 3 to 7. When the molecular weight distribution (Mw / Mn) is in the range of 3 to 7, problems such as whiteout are prevented from occurring even when the liquid crystal panel or the liquid crystal display device is exposed to high temperatures.

It is preferable that the acrylic resin (A) has a glass transition temperature in the range of -10 to -60 占 폚 in order to exhibit adhesiveness. The glass transition temperature of the resin can be generally measured by a differential scanning calorimeter.

The acrylic resin (A) constituting the pressure-sensitive adhesive composition can be produced by various known methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method. In the production of the acrylic resin, a polymerization initiator is usually used. The polymerization initiator is used in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of the total amount 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 and the like. As the thermal polymerization initiator, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile) , 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxy valeronitrile) Azo compounds such as bis (2-methylpropionate) and 2,2'-azobis (2-hydroxymethylpropionitrile); Butyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, Organic peroxides such as neodecanoate, tert-butyl peroxypivalate and (3,5,5-trimethylhexanoyl) peroxide; And inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. A redox-type initiator using a peroxide and a reducing agent in combination may also be used as a polymerization initiator.

As a method for producing an acrylic resin, a solution polymerization method is preferable among the methods shown above.

A specific example of the solution polymerization method will be described. A desired monomer and an organic solvent are mixed, and a thermal polymerization initiator is added in a nitrogen atmosphere. The solution is heated at a temperature of about 40 to 90 캜, preferably about 60 to 80 캜, Followed by stirring. In order to control the reaction, a monomer or a thermal polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a state dissolved in an organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; Esters such as ethyl acetate or butyl acetate; Aliphatic alcohols such as propyl alcohol and isopropyl alcohol; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and the like.

≪ Crosslinking agent (B) >

A crosslinking agent (B) is blended with the above-mentioned acrylic resin (A) to obtain a pressure-sensitive adhesive composition. The crosslinking agent (B) is a compound which reacts with a structural unit derived from the polar functional group-containing monomer (A-3) in the acrylic resin (A) to crosslink the acrylic resin. Specific examples thereof include isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds and the like. Of these, isocyanate-based compounds, epoxy-based compounds and aziridine-based compounds have at least two functional groups capable of reacting with polar functional groups in the acrylic resin (A).

The isocyanate compound is a compound having at least two isocyanate groups (-NCO) in the molecule, and examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, Diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and the like. Adducts obtained by reacting these isocyanate compounds with a polyol such as glycerol or trimethylolpropane, or an isocyanate compound in the form of a dimer, a trimer, or the like, can also be used as a crosslinking agent in a pressure-sensitive adhesive. Two or more isocyanate compounds may be mixed and used.

The epoxy compound is a compound having at least two epoxy groups in the molecule, and examples thereof include bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl N, N, N ', N'-tetraglycidyl-m-hexyldiol diglycidyl ether, trimethylolpropane triglycidyl ether, N, N-diglycidyl aniline, Xylylenediamine, and 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane. Two or more kinds of epoxy compounds may be mixed and used.

The aziridine compound is a compound having at least two skeletons of a tricyclic ring composed of one nitrogen atom and two carbon atoms, which is also called ethyleneimine, in the molecule, and examples thereof include diphenylmethane-4,4'-bis (1-aziridine carboxamide), triethylene melamine, isophthaloyl bis-1- (2-methyl aziridine), tris-1-aziridinylphosphine (1-aziridine carboxamide), trimethylolpropane tris-? -Aziridinyl propionate, tetramethylolmethane tris-? -Aziridinyl propionate, etc. .

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

Of these cross-linking agents, isocyanate compounds, particularly xylylene diisocyanate, tolylene diisocyanate or hexamethylene diisocyanate, or adducts obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylolpropane, or adducts obtained by reacting these isocyanate compounds with dimers , Trimers, etc., and mixtures of these isocyanate compounds are preferably used. When the polar functional group-containing monomer (A-3) has a polar functional group selected from a free carboxyl group, a hydroxyl group, an amino group and an epoxy ring, it is particularly preferable to use an isocyanate compound as at least one of the crosslinking agent (B). Examples of suitable isocyanate compounds include tolylene diisocyanate, adducts obtained by reacting tolylene diisocyanate with a polyol, dimers of tolylene diisocyanate, and trimer of tolylene diisocyanate, and also hexamethylene diisocyanate, hexamethylene diisocyanate Adducts obtained by reacting an isocyanate with a polyol, dimers of hexamethylene diisocyanate, and trimer of hexamethylene diisocyanate.

The crosslinking agent (B) is blended in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the acrylic resin (A). The blending amount of the crosslinking agent (B) is preferably about 0.1 to 5 parts by weight, more preferably about 0.2 to 3 parts by weight, based on 100 parts by weight of the acrylic resin (A). When the amount of the crosslinking agent (B) relative to 100 parts by weight of the acrylic resin (A) is 0.01 parts by weight or more, particularly 0.1 parts by weight or more, the durability of the pressure-sensitive adhesive layer tends to be improved, , So that the whiteout of the liquid crystal panel is not conspicuous.

≪ Other components constituting the pressure-sensitive adhesive composition >

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer in the present invention preferably contains the silane compound (C) in order to improve the adhesion between the pressure-sensitive adhesive layer and the glass cell. Particularly, It is preferable to contain the silane compound (C).

Examples of the silane compound (C) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane , N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethoxydimethyl Silane, and the like. Two or more silane compounds (C) may be used.

The silane compound (C) may be a silicone oligomer type. When a silicone oligomer is represented 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 mercaptopropyl group-containing copolymers such as 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer;

Mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltri A mercapto methyl group-containing copolymer such as a methoxy silane-tetraethoxy silane copolymer;

3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane copolymer Tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane- 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer and 3-methacryloyloxypropylmethyl di Copolymers containing methacryloyloxypropyl groups such as methoxy silane-tetraethoxy silane copolymers;

3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane- 3-acryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer Copolymers containing acryloyloxypropyl groups such as polymers;

Vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer Polymer, vinyl methyl dimethoxy silane-tetramethoxy silane copolymer, vinyl methyl dimethoxy silane-tetraethoxy silane copolymer, vinyl methyl diethoxy silane-tetramethoxy silane copolymer and vinyl methyl diethoxy silane-tetraethoxy Vinyl group-containing copolymers such as silane copolymers;

3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3- Aminopropyltriethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltrimethoxysilane- Methyldiethoxysilane-tetramethoxysilane copolymer, and amino group-containing copolymers such as 3-aminopropylmethyldiethoxysilane-tetraethoxysilane copolymer.

These silane-based compounds (C) are often liquids. The blending amount of the silane compound (C) in the pressure-sensitive adhesive composition is usually about 0.01 to 10 parts by weight based on 100 parts by weight (when two or more kinds are used, the total amount) of the nonvolatile component of the acrylic resin (A) To 1 part by weight. When the amount of the silane compound relative to 100 parts by weight of the nonvolatile matter of the acrylic resin (A) is 0.01 parts by weight or more, particularly 0.03 parts by weight or more, adhesion between the pressure-sensitive adhesive layer and the glass cell is improved. If the amount is 10 parts by weight or less, particularly 1 part by weight or less, bleeding-out of the silane-based compound from the pressure-sensitive adhesive layer tends to be suppressed.

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer in the present invention may contain an ionic compound (D) as an antistatic agent. Particularly when the aromatic ring-containing monomer (A-2) constituting the acrylic resin (A) is the aromatic ring-containing (meth) acrylic compound represented by the formula II and n is 2 or more in the formula II, It is possible to obtain a good antistatic property while maintaining a high whiteout suppressing effect by adding the ionic compound (D) to a pressure-sensitive adhesive composition containing the acrylic resin copolymerized with the monomer. The ionic compound referred to herein is a compound that exists in combination of a cation and an anion. The cation and the anion may be inorganic or organic, respectively. From the viewpoint of compatibility with the acrylic resin (A), at least one of a cation and an anion Is preferably an ionic compound including an organic group.

Examples of the cation constituting the ionic compound include lithium cations, pyridinium cations represented by the following formula III, quaternary ammonium cations represented by the following formula IV, and the like.

In formula (III), R ₅ to R ₉ each 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 (IV), 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 cations represented by the formula (III) have a total number of carbon atoms of 6 or more. Among them, the number of total carbon atoms is preferably 8 or more, particularly 10 or more, from the viewpoint of compatibility with the acrylic resin (A). The total number of carbon atoms is preferably 36 or less, and more preferably 30 or less. Among the pyridinium cations represented by the formula (III), R ₇ bonded to the carbon atom at the 4-position of the pyridine ring is an alkyl group, and R ₅ , R ₆ , R ₈ and R ₉ bonded to other carbon atoms of the pyridine ring are hydrogen An atom is one of the preferred cations. Specific examples of the pyridinium cations represented by the formula (III) 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 and the like.

The ammonium cation represented by the formula IV is a tetraalkylammonium cation, and the tetraalkylammonium cation is preferably 20 or more, more preferably 22 or more, in view of compatibility with the acrylic resin (A). The total number of carbon atoms is preferably 36 or less, and more preferably 30 or less. Specific examples of tetraalkylammonium cations represented by the formula (IV) include the following.

Tetrahexylammonium cation,

Tetraoctylammonium cation,

Tributylmethylammonium cation,

Trihexylmethylammonium cation,

Trioctylmethylammonium cation,

Tridecylmethylammonium cation,

Trihexylethylammonium cation,

Trioctylethylammonium cation and the like.

On the other hand, examples of the anions constituting the 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 (fluorosulfonyl) imide anion [(FSO ₂ ) ₂ N ^- ],

Bis (trifluoromethanesulfonyl) imide anion [(CF ₃ SO ₂ ) ₂ N ^- ],

Tris (trifluoromethanesulfonyl) methanide anion [(CF ₃ SO ₂ ) ₃ C ^- ],

Hexafluoroacetate anion [AsF ₆ ^- ],

Hexafluoroantimonate anion [SbF ₆ ^- ],

Hexafluoroniobate anion [NbF ₆ ^- ],

Hexafluorotantalate anion [TaF ₆ ^- ],

(Poly) hydrofluorofluoride anion [F (HF) _n ^- ] (where n is about 1 to 3),

Thiocyan anion [SCN ^- ]

Dicyanamid anion [(CN) ₂ N ^- ],

A perfluorobutanesulfonate anion [C ₄ F ₉ SO ₃ ^- ],

Bis (pentafluoroethanesulfonyl) imide anion [(C ₂ F ₅ SO ₂ ) ₂ N ^- ],

A perfluorobutanoate anion [C ₃ F ₇ COO ^- ],

(Trifluoromethanesulfonyl) (trifluoromethanecarbonyl) imide anion [(CF ₃ SO ₂ ) (CF ₃ CO) N ^- ] and the like.

Concrete examples of the ionic compound can be appropriately selected from a combination of the above-mentioned cation and anion. Specific examples of the ionic compound which is a combination of a cation and an anion include the following.

Lithium bis (fluorosulfonyl) imide,

Lithium bis (trifluoromethanesulfonyl) imide,

Lithium hexafluorophosphate,

Lithium iodide (lithium iodide),

N-methyl-4-hexylpyridinium bis (fluorosulfonyl) imide,

N-butyl-2-methylpyridinium bis (fluorosulfonyl) imide,

N-hexyl-4-methylpyridinium bis (fluorosulfonyl) imide,

N-octyl-4-methylpyridinium bis (fluorosulfonyl) imide,

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 perchlorate,

N-butyl-2-methylpyridinium perchlorate,

N-hexyl-4-methylpyridinium perchlorate,

N-octyl-4-methylpyridinium perchlorate,

Tetrahexylammonium bis (fluorosulfonyl) imide,

Tributylmethylammonium bis (fluorosulfonyl) imide,

Trihexylmethylammonium bis (fluorosulfonyl) imide,

Trioctylmethylammonium bis (fluorosulfonyl) imide,

Tetrahexylammonium bis (trifluoromethanesulfonyl) imide,

Tributylmethylammonium bis (trifluoromethanesulfonyl) imide,

Trihexylmethylammonium bis (trifluoromethanesulfonyl) imide,

Trioctylmethylammonium bis (trifluoromethanesulfonyl) imide,

Tetrahexylammonium hexafluorophosphate,

Tributylmethylammonium hexafluorophosphate, tributylmethylammonium hexafluorophosphate,

Trihexylmethylammonium hexafluorophosphate,

Trioctylmethylammonium hexafluorophosphate,

Tetrahexylammonium perchlorate,

Tributylmethylammonium perchlorate,

Trihexylmethylammonium perchlorate,

Trioctylmethylammonium perchlorate, and the like.

These ionic compounds may be used alone or in combination with at least one other. When the ionic compound (D) is blended, the amount thereof is usually about 0.5 to 8 parts by weight, preferably 0.8 to 4 parts by weight, based on 100 parts by weight of the acrylic resin (A).

The above-described pressure-sensitive adhesive composition may further contain a crosslinking catalyst, a weathering stabilizer, a tackifier (tackifier), a plasticizer, a softener, a dye, a pigment, an inorganic filler and a resin other than an acrylic resin. It is also useful to form a harder pressure-sensitive adhesive layer by blending an ultraviolet-curing compound in the pressure-sensitive adhesive and irradiating ultraviolet rays after curing the pressure-sensitive adhesive layer. When a crosslinking catalyst is blended with a crosslinking agent in a pressure-sensitive adhesive, it is possible to prepare the pressure-sensitive adhesive layer with aging for a short period of time. In the polarizing plate having a pressure-sensitive adhesive to be obtained, floating or peeling may occur between the polarizing plate and the pressure- Can be suppressed from occurring, and the workability can be further improved in some cases. Examples of the crosslinking catalyst include amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resin and melamine resin . When an amine compound is added to the pressure-sensitive adhesive as a crosslinking catalyst, an isocyanate compound is suitable as the crosslinking agent.

Each of these components constituting the pressure-sensitive adhesive may be mixed with the acrylic resin (A) and the crosslinking agent (B) as essential components in a state in which they are dissolved in a solvent as required, thereby obtaining a pressure-sensitive adhesive composition.

A pressure-sensitive adhesive layer is formed by crosslinking the pressure-sensitive adhesive composition. A specific method for forming the pressure-sensitive adhesive layer includes a method of applying a pressure-sensitive adhesive composition on a suitable substrate and drying the pressure-sensitive adhesive composition.

≪ Gel fraction of pressure-sensitive adhesive layer >

In the present invention, as described above, the gel fraction of the pressure-sensitive adhesive layer is made 60 to 99% by weight. When the gel fraction of the pressure-sensitive adhesive layer is 60% by weight or more, the durability of the pressure-sensitive adhesive layer is improved, and the gel fraction is preferably 99% by weight or less. Here, the gel fraction is a value measured according to the following (1) to (4).

(1) A metal mesh (weight is Wm) made of a pressure-sensitive adhesive layer of about 8 cm × about 8 cm and SUS304 of about 10 cm × about 10 cm is bonded.

(2) The weight of the adhesive obtained in the above (1) is weighed, its weight is made to be Ws, then folded four times so as to surround the pressure-sensitive adhesive layer and fixed with a stapler and weighed to be Wb.

(3) In the above (2), the staple-fixed mesh is placed in a glass container, and 60 mL of ethyl acetate is added to the glass container. The glass container is then kept at room temperature for 3 days.

(4) Take out the mesh from the glass container, dry at 120 DEG C for 24 hours, weigh the weight, and calculate the gel fraction based on the following formula.

Gel fraction (% by weight) = [{Wa- (Wb-Ws) -Wm} / (Ws-Wm)

The gel fraction of the pressure-sensitive adhesive layer can be adjusted, for example, in accordance with the kind of the acrylic resin (A) which is an effective component of the pressure-sensitive adhesive composition and the amount of the crosslinking agent (B). Specifically, when the amount of the polar functional group-containing monomer (A-3) in the acrylic resin (A) is increased or the amount of the crosslinking agent (B) in the pressure-sensitive adhesive composition is increased, the gel fraction becomes higher, The gel fraction may be adjusted according to the amount of the functional group-containing monomer and / or the crosslinking agent. The amount of the structural unit derived from the polar functional group-containing monomer (A-3) in the acrylic resin (A) is preferably in the range of 0.1 to 5% by weight, The gel fraction may be selected and adjusted in such a manner that the gel fraction is in the above-described range in combination with the other components constituting the polymer, and further with the kind and amount of the crosslinking agent. On the other hand, the amount of the crosslinking agent (C) is preferably in the range of about 0.1 to 5 parts by weight based on 100 parts by weight of the nonvolatile matter of the acrylic resin constituting the pressure-sensitive adhesive layer (the total amount when two or more kinds are used) It is preferable to select it according to the kind of resin.

The pressure-sensitive adhesive layers 31 and 32 on the polarizers 21 and 22 can be obtained by applying the pressure-sensitive adhesive composition described above to a release film to form a pressure-sensitive adhesive layer and bonding the obtained pressure-sensitive adhesive layer to the surfaces of the polarizers 21 and 22 A method of applying a pressure sensitive adhesive composition on the polarizing plates 21 and 22 to form a pressure sensitive adhesive layer and protecting the pressure sensitive adhesive surface by bonding a release film to the pressure sensitive adhesive surface. The release film used herein is a film made of various transparent resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyarylate, and the like, and the adhesion surface of the substrate with the pressure- It can be configured that the same mold releasing process is performed.

The thickness of the pressure-sensitive adhesive layers 31 and 32 is not particularly limited, but is usually 30 μm or less, more preferably 10 μm or more, and further preferably 15 to 25 μm.

If the thickness of the pressure-sensitive adhesive layer is 30 占 퐉 or less, the adhesiveness under high temperature and high humidity is improved and the possibility of floating or peeling between the glass cell and the pressure-sensitive adhesive layer tends to be lowered. If the thickness of the polarizing plate is 10 μm or more, even if the size of the polarizing plate adhered to the polarizing plate changes, the pressure-sensitive adhesive layer follows and changes in accordance with the change in the dimension, so that there is no difference between the brightness at the periphery of the liquid- , Whiteout and color unevenness tend to be suppressed. Conventionally, the thickness of the pressure-sensitive adhesive layer adhered to a glass cell for liquid crystal display has conventionally been considered to be 25 占 퐉, but in the present invention, even when the thickness is 20 占 퐉 or less, sufficient performance as a pressure-sensitive adhesive layer is exhibited.

The polarizing plate on which the pressure-sensitive adhesive layer according to the present invention is formed adheres to the liquid crystal cell to form a liquid crystal panel. When the polarizing plate is peeled off from the liquid crystal cell, the pressure-sensitive adhesive layer is peeled off along the polarizing plate, It is easy to fix a polarizing plate having a pressure-sensitive adhesive layer on the liquid crystal cell after peeling since dark portions and adhesive residue are hardly generated on the surface of the liquid crystal cell that has been touched. That is, the so-called reworkability is excellent.

[Polarizer]

The first polarizing plate 21 and the second polarizing plate 22 shown in FIG. 1 each transmit linearly polarized light having a certain vibration surface among light incident perpendicularly to the surface thereof, and linearly polarized light having a vibration surface orthogonal thereto And a polarizing film that absorbs light. Such a polarizing film is usually produced by adsorbing and orienting a dichroic dye made of iodine or a dichroic organic dye to a polyvinyl alcohol based resin film. Since the polarizing film itself is highly stretched to orient the dichroic dye, it tends to be torn. Therefore, usually, a transparent protective layer is formed on at least one surface of the polarizing film as described above to form a polarizing plate.

An example of the layer structure of a polarizing plate having a pressure-sensitive adhesive layer for adhering to a liquid crystal cell suitable for application to the present invention is shown in a schematic cross-sectional view in Fig. In Fig. 2, the reference numeral 20 is attached to the polarizing plate to mean both the first polarizing plate 21 and the second polarizing plate 22 shown in Fig. In addition, since it means both of the first pressure-sensitive adhesive layer 31 and the second pressure-sensitive adhesive layer 32 shown in Fig. 1, reference numeral 30 is attached to the pressure-sensitive adhesive layer used for pressure-sensitive adhesion to the liquid crystal cell. The first polarizing plate 21 and the second polarizing plate 22 may have the same layer configuration or different layer configurations.

One form of the polarizing plate 20 is one in which transparent protective layers 26 and 27 are formed on both surfaces of a polarizing film 25 as shown in Fig. (The outer surface of the transparent protective layer 27, for example), a pressure-sensitive adhesive layer 30 for applying liquid crystal cell spots is formed. 2 (B), the transparent protective layers 26 and 27 are formed on both surfaces of the polarizing film 25, and the surface of the polarizing film 25 which is the liquid crystal cell side (The outer surface of the optical compensation film 27), an optical compensation film 28, which is a typical example of a phase difference film, is laminated, and a spot-on-adhesive layer 30 is formed on the outside of the optical compensation film 28 . In this case, the interlaminar adhesive 29 is usually used to bond the transparent protective layer 27 to the optical compensation film 28.

Another form of the polarizing plate 20 is such that a transparent protective layer 26 is formed on one side of the polarizing film 25 as shown in Fig. 2 (C) Sensitive adhesive layer 30 on the liquid crystal cell is formed on the other surface of the polarizing film 25, as shown in Fig. 2 (D), a transparent protective layer 26 is formed on one side of the polarizing film 25, and an interlayer adhesive 29 is provided on the other side of the polarizing film 25 An optical compensation film 28 having a retardation film as a representative example is laminated, and a spot-on-pressure-sensitive adhesive layer 30 on the liquid crystal cell is formed outside the optical compensation film 28.

The transparent protective layers 26 and 27 can be formed, for example, by coating a resin, but in many cases, they are often constituted by adhering a protective film through an adhesive. As the protective film, for example, various transparent resin films such as a cellulose resin film, an olefin resin film, a cycloolefin resin film, an acrylic resin film, and a polyester resin film can be used.

When a cellulose resin film is used as the protective film, a cellulose acetate resin in which at least a part of the cellulose is esterified is suitable. For example, triacetylcellulose, diacetylcellulose, cellulose acetate propionate and the like can be mentioned. Such acetic acid-based resin film can be suitably used on the market. For example, "Fuji Tach TD80", "Fuji Tach TD80UF" and "Fuji Tach TD80UZ" sold by Fuji Film Co., Ltd., "KC8UX2M" and "KC8UY" sold by Konica Minolta Opt Co., ) Are suitable examples.

The cycloolefin-based resin is a thermoplastic resin having a monomer unit of cycloolefin represented by, for example, norbornene or tetracyclododecene (alias dimethano-octahydronaphthalene) or a derivative thereof, and the ring- Or a hydrogenated product of a ring-opening copolymer using two or more kinds of cycloolefins, or an addition copolymer of a cycloolefin and an aromatic compound having a chain type olefin or vinyl group. A polar group may be introduced.

Examples of commercially available thermoplastic cycloolefin resins include "ARTON" sold by JSR Corporation, "ZEONEX" and "Zeonor" sold by Nippon Zeon Co., TOPAS ", which is manufactured by TOPAS ADVANCED POLYMERS GmbH of Germany and sold by Polyplastics Co., Ltd., and" APEL "(all trade names), which is sold by Mitsui Gagaku Co., Ltd. in Japan.

When the cycloolefin resin is formed into a film, known film forming techniques such as a solvent casting method and a melt extrusion method are appropriately used for the film formation. A cycloolefin-based resin film formed or a cycloolefin-based resin film stretched and given a phase difference is also commercially available. For example, " ATSON FILM "sold by JSR Corporation," Zeonoah Film "sold by Nippon Zeon Co., Ltd., and" SCA40 "sold by Sekisui Chemical Co., (All trade names), and these can be suitably used.

As described above, at least one side of the polarizing film, usually, the protective film as described above is laminated on at least the surface farther from the liquid crystal cell 10 with reference to Fig.

As shown in Fig. 2 (A), the transparent protective film 27 can be laminated on the surface of the polarizing film 25 on the side of the liquid crystal cell through an adhesive. Further, as shown in Fig. 2 (B) Likewise, the optical compensation film 28 may be adhered to the outside via the interlaminar adhesive 29. As shown in Fig. 2 (C), on this surface, a spot-on-pressure sensitive adhesive layer 30 is formed directly on the liquid crystal cell, or alternatively, as shown in Fig. 2 (D) The compensation film 28 can be bonded. Here, the pressure-sensitive adhesive layer 30 directly adhered to the liquid crystal cell 10 is preferably formed from the pressure-sensitive adhesive composition specified in the present invention described above. Alternatively, the optical compensation film 28 may be adhered to the protective film 27, The interlaminar adhesive 29 for adhering the optical compensation film 28 to the polarizing film 25 may be formed from another pressure sensitive adhesive composition. The interlayer pressure-sensitive adhesive 29 used for adhering the optical compensation film 28 to the protective film 27 or the polarizing film 25 is not limited to the above description Sensitive adhesive composition in which a crosslinking agent is blended with an acrylic resin similar to the acrylic pressure-sensitive adhesive composition.

In the liquid crystal panel shown in Fig. 1, at least one of the first polarizing plate 21 and the second polarizing plate 22 is constituted by a protective film 26 / polarizing film (not shown) as shown in Fig. 2A 25) / protective film 27 is preferable.

The protective film 26 disposed on the side farther from the liquid crystal cell of the polarizing film 25 is preferably composed of a cellulose acetate based resin film including a triacetyl cellulose film from the viewpoints of ease of putting the surface treatment layer and optical properties Do. Particularly, a cellulose acetate resin film in which the in-plane retardation value Ro is in the range of 0 to 20 nm and the retardation value (Rth) in the thickness direction is in the range of 20 to 80 nm can be directly produced by the solvent casting method It is one of preferable protective films disposed on the side far from the liquid crystal cell.

Herein, with respect to the film exhibiting optically anisotropy, the in-plane retardation value Ro and the thickness direction retardation value Rth are set so that the refractive index in the in-plane slow axis direction is n _x , the direction in the plane (the fast axis direction) (5) and (6) below, where n _y is the refractive index of the first layer, n _z is the refractive index in the thickness direction, and d is the thickness.

Ro = (n _x -n _y ) d (5)

Rth = _{[(n x + n y) /} 2-n z ] × d (6)

2 (B) and (D), the optical compensation film 28 may be disposed on the liquid crystal cell side of the polarizing plate 20, or the optical compensation film 28 may be disposed on the liquid crystal cell side of the polarizing plate 20, It is preferable that the protective film 27 itself serving as the liquid crystal cell of the polarizing plate 20 in the example shown in Fig. An appropriate value can be arbitrarily selected as the value of the retardation in the optical compensation film or the protective film to which the retardation is imparted depending on the mode of the liquid crystal and the intended image quality.

For example, when the polarizing plate is provided with the compensating function for the liquid crystal display of the vertical alignment (VA) mode, at least a protective film disposed on the liquid crystal cell side of the light incidence side polarizer and a protective film disposed on the liquid crystal cell side of the light exit- It is preferable that one of them has a function of a retardation film. In this case, the protective film having the function of the retardation film has the slow axis and the fast axis in the plane. The ground axis and the leading phase axis are orthogonal to each other in the plane.

At least one of the protective films 27 located on the liquid crystal cell side of the light incident-side polarizing plate and the light-exiting-side polarizing plate has a retardation value Ro in the plane, And the retardation value (Rth) in the thickness direction is in the range of 80 to 250 nm. In this case, it is preferable that the slow axis direction of the protective film 27 having a phase difference is arranged so as to be substantially orthogonal to the absorption axis direction of the polarizing film 25 being bonded. It is more preferable that both of the protective films 27 located on the liquid crystal cell side of the polarizing plates disposed on both sides of the liquid crystal cell are formed of films having such retardation values.

When the retardation value Ro in the plane of the protective film serving as the liquid crystal cell in the polarizing plate used for adhesion to the liquid crystal cell of VA mode is less than 30 nm, the time compensation of the polarization axis becomes insufficient, The oblique angle) is increased and the viewing angle tends to become narrow. On the other hand, if the value exceeds 80 nm, on the other hand, the time may be overcompensated and adversely affect the light dropout. If the retardation value (Rth) in the thickness direction is too small as well as the in-plane retardation value, the time compensation of the liquid crystal layer tends to be insufficient.

The cellulose acetate based resin film can give an arbitrary retardation value by stretching. A cellulose acetate resin film having a phase difference exhibiting a phase difference suitable for optical compensation of a liquid crystal cell in a VA mode is commercially available which exhibits a phase difference in biaxial orientation by stretching.

For example, there are "KC8UCR-5", "KC4FR-T", and "KC4HR-T" (all trade names) sold by Konica Minolta Opt. The cellulose acylate resin film having such a retardation can be preferably used as a protective film (protective film 27 in Fig. 2 (A)) to be a liquid crystal cell.

The cycloolefin resin film can also be given an arbitrary retardation value by stretching. The stretching is usually carried out continuously while the film is wound from the roll, and is stretched in the heating furnace, in the traveling direction of the roll, or in the direction perpendicular to the traveling direction. The temperature of the heating furnace is usually in the range of the glass transition temperature + 100 DEG C in the vicinity of the glass transition temperature of the cycloolefin-based resin. Preferably, the film is stretched so that the direction perpendicular to the traveling direction of the roll becomes the main stretching axis, that is, the transverse stretching is the main body. The draw ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times in the main stretching axis direction. The cycloolefin-based resin film to which such retardation is imparted can also be suitably applied as a protective film (protective film 27 in Fig. 2 (A)) to be a liquid crystal cell.

In one preferred embodiment of the VA mode liquid crystal panel, at least one of the first polarizing plate 21 and the second polarizing plate 22 shown in Fig. 1 is a protective film such as shown in Fig. 2 (A) Polarizing film 26 / polarizing film 25 / protective film 27 as shown in Fig. In one more preferred form of this case, the protective film 26, which is farther from the liquid crystal cell than the two protective films sandwiching the polarizing film 25, has a retardation value Ro in the plane of 0 to 20 nm and a retardation value (Rth) in the thickness direction of 20 to 80 nm, and the protective film (27) as a liquid crystal cell has a retardation value (Ro) in the plane of 30 to 80 nm, Direction retardation value (Rth) of 80 to 250 nm.

On the other hand, when an effective compensation function is applied to the polarizing plate in the liquid crystal cell of the transverse electric field (IPS) mode, at least one of the light-incident-side polarizers and the light- It is preferable that the retardation value Ro is in the range of 0 to 10 nm and the retardation value (Rth) in the thickness direction is in the range of -25 to 25 nm, and more preferably, a substantially no-oriented film having almost zero Rth is used Do. It is more preferable that both of the protective films positioned on the liquid crystal cell sides of the polarizing plates disposed on both surfaces of the liquid crystal cell have such a retardation value. By setting the in-plane retardation value Ro and the thickness direction retardation value Rth within the above-mentioned range, the amount of light shielding in the oblique direction is small, and clear display becomes possible.

As a film suitable for the compensation of the IPS mode as described above, a cellulose acetate resin film or a cycloolefin resin film can be preferably used. Films having a retardation value (Rth) in the thickness direction substantially reduced by adding a retardation reducing agent to a cellulose acetate resin are commercially available. Examples thereof include "KC4UEW" and "KC4UESW" sold by Konica Minolta Opt Quot; (all trade names). Such a cellulose acetate resin film having a controlled retardation can be suitably applied as a protective film (protective film 27 in Fig. 2 (A)) to be a liquid crystal cell.

As the cycloolefin-based resin film in which the retardation value in the in-plane direction Ro and the retardation value in the thickness direction Rth are reduced as much as possible, the above-mentioned cycloolefin- And a method of modifying the strain by heat treatment or the like can be applied.

In the IPS mode liquid crystal panel, in at least one preferred embodiment, at least one of the first polarizing plate 21 and the second polarizing plate 22 shown in Fig. 1 has a structure similar to that shown in Fig. 2 (A) The protective film 26 / the polarizing film 25 / the protective film 27. In one more preferred form of this case, among the two protective films sandwiching the polarizing film 25, the protective film 26 far from the liquid crystal cell has a retardation value Ro in the plane of 0 to 20 nm The retardation value Ro in the plane is 0 to 10 nm and the retardation value in the thickness direction (retardation value in the thickness direction is 20 to 80 nm) Rth) of -25 to 25 nm.

At least one of the first polarizing plate 21 and the second polarizing plate 22 shown in Fig. 1 is replaced with a protective film 26 / polarizing film 25 / protective film 27), in another preferred embodiment, the protective film 26 that is farther from the liquid crystal cell is made of a cellulose acetate resin, and the protective film 27 that is the liquid crystal cell is made of a cycloolefin resin do.

When the liquid crystal cell side protective film of the light incidence side polarizing plate has a retardation and when the liquid crystal cell side protective film of the light output side polarizing plate has a retardation, the polarizing film and the liquid crystal cell side protective film constituting the light incidence side polarizing plate, The polarizing film and the liquid crystal cell side protective film constituting the polarizing plate may be arranged such that the absorption axis of the polarizing film and the in-plane slow axis of the protective film are in a substantially parallel relationship or a nearly orthogonal relationship. Particularly, it is preferable from the viewpoint of productivity to arrange them so that they are almost orthogonal to each other. That is, when the liquid crystal cell side protective film of the light incidence side polarizing plate and / or the liquid crystal cell side protective film of the light output side polarizing plate are composed of a refractive index anisotropic film having a retardation, it is preferable that the film is produced by a stretching operation mainly comprising transverse stretching, In this case, since the slow axis in the case is in the width direction of the roll film, the polarizing film in which the longitudinal direction (flow direction) of the roll film is the absorption axis is roll-to-roll bonded so that the absorption axis of the polarizing film and the slow axis of the protective film are orthogonal do.

In the cellulose acetate based resin film, saponification treatment is generally carried out in order to improve the adhesion with the polarizing film. As the saponification treatment, a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide can be adopted.

The protective film used for the polarizing plate preferably has a smaller thickness, but if it is too thin, the strength tends to deteriorate and workability tends to be poor. When the protective film is too thick, the transparency decreases or the weight of the polarizing plate increases There is a tendency. From this viewpoint, the thickness of the protective film is usually 5 to 200 占 퐉, preferably 10 to 150 占 퐉, more preferably 20 to 100 占 퐉 in the case of the protective film made of cycloolefin resin, In the case of a protective film made of a resin, it is usually 20 to 200 占 퐉, preferably 30 to 150 占 퐉, and more preferably 40 to 100 占 퐉.

The protective film constituting the polarizing plate may be subjected to a surface treatment such as antiglare treatment, hard coat treatment, antistatic treatment or antireflection treatment on the surface opposite to the surface to which the polarizing film is adhered. A coating layer made of a liquid crystalline compound or its high molecular weight compound may be formed on the surface of the protective film opposite to the surface to be adhered to the polarizing film.

[Liquid crystal display device]

The liquid crystal panel shown in Fig. 1 can be a liquid crystal display device by disposing the back light on the outside of either the first polarizing plate 21 or the second polarizing plate 22. [ Various known optical layers such as a light-converging layer, a light-diffusing layer, and a brightness enhancing layer may be disposed between the back light and the polarizing plate depending on display characteristics required for the liquid crystal display device.

The liquid crystal display device using the liquid crystal panel of the present invention can be applied to a liquid crystal display for a personal computer including a notebook type, a desktop type, a PDA (Personal Digital Assistance), a television, a vehicle-mounted display, Cameras, digital video cameras, electronic calculators, clocks, and more. Particularly, the present invention is effective for a liquid crystal television having a tendency of becoming larger recently.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In the examples, " part " and "% " representing amounts used or contents are based on weight unless specifically noted.

In the following examples, the weight-average molecular weight and the number-average molecular weight were measured by using a GPC apparatus in which four columns of "TSKgel XL" manufactured by Tosoh Corporation (trade name; manufactured by Showa Denko K.K. Five lines of "Shodex GPC KF-802" sold in series were connected in series. Using tetrahydrofuran as the eluent, a sample concentration of 5 mg / mL, a sample introduction amount of 100 μL, a temperature of 40 ° C., 1 mL / min, as measured by standard polystyrene conversion.

First, a production example of an acrylic resin as a main component of a pressure-sensitive adhesive composition is shown.

[Polymerization Example 1]

A reaction vessel equipped with a stirrer, a condenser tube, a nitrogen inlet tube, a thermometer and a stirrer was charged with 81.8 parts of ethyl acetate, 93.4 parts of butyl acrylate as (A-1), 5.0 parts of 2-phenoxyethyl acrylate as (A- -3), 1.0 part of 2-hydroxyethyl acrylate and 0.6 part of acrylic acid were charged and the internal temperature was raised to 55 DEG C while oxygen was removed by replacing air in the apparatus with nitrogen gas. Thereafter, a total amount of a solution obtained by dissolving 0.14 part of azobisisobutyronitrile as a polymerization initiator in 10 parts of ethyl acetate was added. Ethyl acetate was continuously added into the reaction vessel at an addition rate of 17.3 parts / hr while maintaining the internal temperature at 54 to 56 占 폚, and the concentration of the acrylic resin was 35% , The addition of ethyl acetate was stopped and the temperature was maintained at this temperature from the start of the addition of ethyl acetate until the elapse of 12 hours. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20%. The obtained acrylic resin had a weight average molecular weight (Mw) of 1,650,000 and a Mw / Mn of 4.3 as measured by GPC in terms of polystyrene. This is referred to as acrylic resin A. The structural unit derived from 2-phenoxyethyl acrylate as an aromatic ring-containing monomer in the acrylic resin A is 5%, the structural unit derived from 2-hydroxyethyl acrylate as the hydroxyl group-containing monomer is 1%, the acrylic monomer Is 0.6%.

[Polymerization Example 2]

The composition of the monomer was changed to 72.4 parts of butyl acrylate and 20 parts of methyl acrylate as (A-1), 6.0 parts of 2-phenoxyethyl acrylate as (A-2) and 1.0 part of 2-hydroxyethyl acrylate as acrylic acid (A- 0.6 part, and the keeping time of 12 hours was changed to 18 hours, an ethyl acetate solution of an acrylic resin was obtained in the same manner as in Polymerization Example 1. The obtained acrylic resin had a weight average molecular weight (Mw) of 1,470,000 and a Mw / Mn of 5.3 as measured by GPC in terms of polystyrene. This is referred to as acrylic resin B.

The structural unit derived from 2-phenoxyethyl acrylate as an aromatic ring-containing monomer in the acrylic resin B is 6%, and the structural unit derived from 2-hydroxyethyl acrylate as the hydroxyl group-containing monomer is 1%, acrylic acid Is 0.6%.

[Polymerization Examples 3 to 10]

The composition of the monomers was changed as shown in Table 1, and otherwise, an ethyl acetate solution of an acrylic resin was obtained in the same manner as in Polymerization Example 1. The weight average molecular weight (Mw) and Mw / Mn of the obtained acrylic resin in terms of polystyrene by GPC are as shown in Table 1, and the respective acrylic resins are referred to as acrylic resins C to J as shown in Table 1 . On the other hand, Polymerization Examples 7 to 10 are examples in which the amount of the aromatic ring-containing monomer does not satisfy the requirements of the acrylic resin (A) specified in the present invention.

[Polymerization Example 11]

The composition of the monomers was as shown in Table 1, and these mixed solutions were put in the same reaction vessel as used in Polymerization Example 1. The internal temperature was raised to 55 캜 while oxygen was replaced with nitrogen gas by replacing air in the apparatus. Thereafter, a total amount of a solution obtained by dissolving 0.14 part of azobisisobutyronitrile as a polymerization initiator in 10 parts of ethyl acetate was added. Ethyl acetate was continuously added into the reaction vessel at an addition rate of 17.3 parts / hr while maintaining the internal temperature at 54 to 56 占 폚, and the concentration of the acrylic resin was 35% , The addition of ethyl acetate was stopped and the temperature was maintained at this temperature for 4 hours from the start of the addition of ethyl acetate. Then, 0.2 part of azobisisobutyronitrile was dissolved in 10 parts of ethyl acetate, and the whole was heated at the same temperature for 8 hours. Ethyl acetate was added to adjust the concentration of the acrylic resin to 20%. The obtained acrylic resin had a weight average molecular weight (Mw) of 1,070,000 and a Mw / Mn of 8.2 as measured by GPC in terms of polystyrene. This is referred to as an acrylic resin K. The structural unit derived from 2-phenoxyethyl acrylate as an aromatic ring-containing monomer in the acrylic resin K is 8%, the structural unit derived from 2-hydroxyethyl acrylate as the hydroxyl group-containing monomer is 1%, the acrylic monomer Is 0.4%. Polymerization Example 11 is an example in which Mw / Mn does not satisfy the requirements of the acrylic resin (A) specified in the present invention.

[Polymerization Example 12]

The composition of the monomer was changed to 70.8 parts of butyl acrylate and 20 parts of methyl acrylate as the component (A-1), 8.0 parts of 2- (2-phenoxyethoxy) ethyl acrylate as the component (A- Except that 1.0 parts of Roxybutyl and 0.2 parts of acrylic acid were used. Otherwise, an ethyl acetate solution of an acrylic resin was obtained in the same manner as in Polymerization Example 1. The obtained acrylic resin had a weight average molecular weight (Mw) of 1,670,000 and a Mw / Mn of 3.9 in terms of polystyrene by GPC. This is referred to as an acrylic resin L. The structural unit derived from 2- (2-phenoxyethoxy) ethyl acrylate as an aromatic ring-containing monomer in the acrylic resin L is 8%, and the structural unit derived from 4-hydroxybutyl acrylate, which is a hydroxyl group- , And the structural unit derived from acrylic acid as a carboxyl group-containing monomer is 0.2%.

[Polymerization Examples 13 to 16]

The monomer composition was changed as shown in Table 2, and an ethyl acetate solution of an acrylic resin was obtained in the same manner as in Polymerization Example 12 except for this. The weight average molecular weights (Mw) and Mw / Mn of the obtained acrylic resin in terms of polystyrene by GPC were as shown in Table 2, and the respective acrylic resins were changed to acrylic resins M to P as shown in Table 2 .

[Polymerization Example 17]

The monomer composition was changed to 88.6 parts of butyl acrylate as a monomer (A-1), 10 parts of 2-methoxyethyl acrylate and 1.0 part of 2-hydroxyethyl acrylate and 0.2 part of acrylic acid as the monomer (A-3) Otherwise, an ethyl acetate solution of an acrylic resin was obtained in the same manner as in Polymerization Example 1. The obtained acrylic resin had a weight average molecular weight (Mw) of 1,750,000 and a Mw / Mn of 4.9 in terms of polystyrene by GPC. This is referred to as an acrylic resin Q. In the acrylic resin Q, a structural unit derived from an aromatic ring-containing monomer is not present, a structural unit derived from 2-hydroxyethyl acrylate as a monomer containing a hydroxyl group is 1%, a structural unit derived from acrylic acid as a carboxyl group- to be.

[Polymerization Examples 18 and 19]

In the monomer composition (A-1), in Polymerization Example 18, 78.6 parts of butyl acrylate and 20 parts of 2-methoxyethyl acrylate were used, and in Polymerization Example 19, 98.6 parts of butyl acrylate was used. To obtain an ethyl acetate solution of the resin. The weight average molecular weight (Mw) and Mw / Mn of the obtained acrylic resin in terms of polystyrene by GPC were as shown in Table 1, and the respective acrylic resins were changed to acrylic resins R and S do.

Polymerization Examples 17 and 18 are examples in which an acrylic resin was produced by copolymerizing 10% or 20% of 2-methoxyethyl acrylate, which is effective for improving antistatic performance, instead of aromatic ring-containing monomer. In Polymerization Example 19, Methacryloxypropyl acrylate, 2-methoxyethyl acrylate, and 2-hydroxyethyl acrylate and acrylic acid, which are monomers containing a polar functional group.

Next, examples and comparative examples in which a pressure-sensitive adhesive composition is prepared using the acrylic resins A to K prepared in Polymerization Examples 1 to 11 and applied to a polarizing plate to produce a liquid-crystal panel corresponding article are shown. In these Examples and Comparative Examples, the following were used as the crosslinking agent and the silane-based compound, respectively (all trade names).

<Cross-linking agent>

Colonate L: Trimethylolpropane adduct of tolylene diisocyanate in ethyl acetate (solids concentration 75%), available from Nippon Polyurethane Co., Ltd.

&Lt; Silane-based compound &

KBM-403: glycidoxypropyltrimethoxysilane (liquid), obtained from Shin-Etsu Chemical Co., Ltd.

[Examples 1 to 6 and Comparative Examples 1 to 5]

(a) Preparation of pressure-sensitive adhesive composition

0.5 parts of the above silane compound (KBM-403) and 0.5 parts of a crosslinking agent (colloquine L) were added to 100 parts of each of the acrylic resins A to K (20% ethyl acetate solution) obtained in Polymerization Examples 1 to 11 Each of the amounts shown in Table 3 were mixed and ethyl acetate was added thereto so that the solid concentration became 13%, thereby preparing a pressure-sensitive adhesive composition.

(b) Production of a polarizing plate having a pressure-sensitive adhesive layer

Each of the pressure-sensitive adhesive compositions prepared in (a) above was applied to the release treated surface of a release-treated polyethylene terephthalate film (trade name "PET 3811 ", available from Lin Tec Co., Ltd., referred to as a separator) And dried at 90 DEG C for 1 minute to prepare a sheet-form pressure-sensitive adhesive layer. Subsequently, on one surface of a polarizing plate having a three-layer structure sandwiched between two surfaces of a polarizing film in which iodine was adsorbed and oriented in polyvinyl alcohol with a protective film made of triacetylcellulose, a surface opposite to the separator of the sheet- (Pressure-sensitive adhesive surface) was bonded by a laminator, and then cured for 7 days at a temperature of 23 캜 and a relative humidity of 65% to prepare a polarizing plate having a pressure-sensitive adhesive layer. For each of the pressure-sensitive adhesive layers after curing, the gel fraction was measured by the method described above, and the results are summarized in Table 2.

(c) Adhesion and evaluation to a glass substrate

A separator was peeled off from a polarizing plate having the pressure-sensitive adhesive layer prepared in (b) above on both sides of a glass substrate for a liquid crystal cell ("Eagle 2000" (trade name) manufactured by Corning Inc.). At this time, on one side of the glass substrate, the absorption axis of the second polarizing plate was perpendicular to the absorption axis of the first polarizing plate so that the absorption axis of the first polarizing plate was parallel to the long side of the glass substrate . The laminate thus obtained was subjected to an heat resistance test in which it was stored for 96 hours under a drying condition at a temperature of 80 캜. Thereafter, the state of expression of the whiteout when light was incident on one of the polarizing plates was visually confirmed. The results were classified into the following criteria and shown in the column of &quot; whiteout (drying at 80 캜) &quot; in Table 3.

&Lt; Expression state of whiteout >

◎: No whiteout is seen at all.

○: Whiteout is hardly noticeable.

△: White out is slightly noticeable.

X: Whiteout is significantly recognized.

The laminate obtained by adhering the polarizing plate to both surfaces of the glass substrate in the same manner as described above was subjected to a heat resistance test (indicated as "heat resistance" in Table 3) in which the temperature was kept at 80 ° C. for 300 hours under dry conditions, (The "wet heat resistance" in Table 3) in which the temperature was kept at 90% for 300 hours and the temperature was lowered to -30 ° C in the state of heating at 70 ° C and then the temperature was raised to 70 ° C in one cycle Hour), and subjected to a heat-resistant impact test (indicated as &quot; inner HS &quot; in Table 3) in which this was repeated 100 times. Then, the laminate after each test was visually observed, and the results were classified according to the following criteria and listed in the "durability" column of Table 3.

&Lt; Evaluation Criteria of Heat Resistance Test, Humidity Heat Test and Heat Resistance Impact Test >

?: No change in appearance such as floating, peeling, and foaming is observed at all.

○: Almost no change in appearance such as floating, peeling, and foaming is observed.

△: Appearance changes such as floating, peeling, and foaming are slightly visible.

X: Changes in appearance such as floating, peeling, foaming and the like are remarkably recognized.

(d) Evaluation of lithographic properties of a polarizing plate having a pressure-sensitive adhesive layer

The lithographic properties of the polarizing plate having the pressure-sensitive adhesive layer prepared in (b) above were evaluated in the following manner. First, a polarizing plate having a pressure-sensitive adhesive layer was cut into test pieces of 25 mm x 150 mm in size. Subsequently, this test piece was adhered to the glass substrate for a liquid crystal cell using the attached device ("Lamipaka" (trade name), manufactured by Fuji Plasma Co., Ltd.) on the side of the pressure sensitive adhesive layer and heated at 50 ° C. at 5 kg / ) For 20 minutes. After heating at 70 DEG C for 2 hours and then in an oven at 50 DEG C for 48 hours, the polarizing plate was peeled from the pressure-sensitive adhesive test piece at a rate of 300 mm / minute in an atmosphere of a temperature of 23 DEG C and a relative humidity of 50% And the state of the surface of the glass plate was observed and classified according to the following criteria. The results are shown in Table 3.

<Evaluation Criteria for Re-workability>

&Amp; cir &amp;: No dark part or the like is recognized on the surface of the glass plate at all.

?: Almost no dark areas were recognized on the surface of the glass plate.

?: Dark part or the like is recognized on the surface of the glass plate.

X: Residue of pressure-sensitive adhesive is recognized on the surface of the glass plate.

As can be seen from Tables 1 and 3, a specific amount of a crosslinking agent is blended with a specific acrylic resin specified in the present invention to constitute a pressure-sensitive adhesive composition, which is used as a pressure-sensitive adhesive layer of a polarizing plate, Examples 1 to 6 in which the absorption axis of one of the polarizing plates was parallel to the long side of the glass substrate and the other of the polarizing plates was adhered so as to be orthogonal to the polarizing plate of the other polarizing plate , White out prevention property, durability and reworkability were excellent. In particular, Examples 3 and 4 having a structural unit derived from an aromatic ring-containing monomer in an amount of 8% or 10% in an acrylic resin have excellent performance in preventing whiteout.

On the other hand, Comparative Examples 1 to 3 in which the content of the structural unit derived from the aromatic ring-containing monomer was 20% or more in the acrylic resin, Comparative Example 4 in which no structural unit derived from an aromatic ring- In Comparative Example 5 in which the Mw / Mn of the resin exceeds 7, all of the whiteout preventing properties are insufficient.

Subsequently, the acrylic resins L to S prepared in Polymerization Examples 12 to 19 were used to prepare a pressure-sensitive adhesive composition without or in combination with an ionic compound, applying it to a polarizing plate, and producing a liquid- For example. In the following examples, the same crosslinking agents and silane compounds as those of Examples 1 to 6 and Comparative Examples 1 to 5 were used. As the ionic compound, N-octyl-4-methylpyridinium hexafluorophosphate (having the structure of the following formula) was used.

[Examples 7 to 11 and Comparative Examples 6 to 9]

(a) Preparation of pressure-sensitive adhesive composition

0.5 parts of the aforementioned silane compound (KBM-403), 0.5 parts of a crosslinking agent (colloquine L) was added to 100 parts of each of the acrylic resin L to S (20% ethyl acetate solution) obtained in Polymerization Examples 12 to 19 The amounts and the ionic compounds shown in Table 4 were mixed in the amounts shown in Table 4 (except that the ionic compound was not used in Example 7 and Comparative Example 8), and ethyl acetate was added so that the solid concentration was 13% To prepare a pressure-sensitive adhesive composition.

(b) Production of a polarizing plate having a pressure-sensitive adhesive layer

Each of the pressure-sensitive adhesive compositions prepared in the above (a) was applied to the releasably treated polyethylene terephthalate film (trade name "PET 3811 ", trade name, And dried at 90 DEG C for 1 minute to prepare a sheet-type pressure-sensitive adhesive layer. Subsequently, both sides of the polarizing film in which iodine was adsorbed and oriented in polyvinyl alcohol was coated with a protective film made of triacetylcellulose (Pressure-sensitive adhesive side) opposite to the separator of the sheet-like pressure-sensitive adhesive layer obtained above was bonded to one side of a polarizing plate having a three-layer structure sandwiched between the two substrates, and then cured for 7 days under conditions of a temperature of 23 DEG C and a relative humidity of 65% To prepare a polarizing plate having a pressure-sensitive adhesive layer.

(c) Evaluation of a polarizing plate having a pressure-sensitive adhesive

The surface resistivity of the pressure-sensitive adhesive layer was measured with a surface intrinsic resistivity meter ("Hirest-up MCP-HT450" (trade name), manufactured by Mitsubishi Chemical Corporation) when the separator was peeled off with respect to each of the obtained polarizers having the pressure- To evaluate the antistatic property. If the surface resistance value is 10 &lt; ¹¹ &gt; ohm / square or less, good antistatic properties can be obtained. The antistatic property was evaluated immediately after curing of the polarizing film having the pressure-sensitive adhesive layer was completed. The results are summarized in Table 4. In addition, the expression state, durability and reworkability of the whiteout were evaluated in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 5, and these results were also summarized in Table 4, did.

As can be seen from Tables 2 and 4, the aromatic ring-containing (meth) acrylic compound represented by the formula (II) as the aromatic ring-containing monomer (A-2) in the acrylic resin (A) In Example 7 using n in which n in the formula (1) was 2, excellent results were obtained in both whiteout prevention property, durability and reworkability. Especially, the effect of preventing whiteout was high.

Examples 8 and 9 using a composition almost equivalent to that obtained by adding an ionic compound to the pressure-sensitive adhesive composition of Example 7 were also excellent in anti-whiteout property, durability and reworkability, . On the other hand, in Example 10 using an aromatic ring-containing (meth) acrylic compound represented by Formula II as the aromatic ring-containing monomer (A-2) in the acrylic resin (A) constituting the pressure- And 11 degrees show good antistatic properties by incorporating an ionic compound.

On the other hand, it is known that the acrylic resin (A) constituting the pressure-sensitive adhesive composition does not have a structural unit derived from an aromatic ring-containing monomer and instead has an effect of improving antistatic performance in combination with an ionic compound Comparative Examples 6 and 7 in which an acrylic resin obtained by copolymerizing 2-methoxyethyl with 10% or 20% and an ionic compound was blended with the acrylic resin to give a good antistatic property, Is lacking. On the other hand, Comparative Examples 8 and 9 using an acrylic resin having only a polar functional group-containing monomer copolymerized with butyl acrylate were also deficient in whiteout prevention irrespective of the presence or absence of ionic compound incorporation.

In the above examples and comparative examples, experiments were conducted by attaching a polarizing plate to the front and back surfaces of a glass substrate that does not sandwich the liquid crystal therebetween. However, since whiteout occurs due to expansion and contraction of the polarizing plate due to heat, . Further, each test of heat resistance, moisture resistance and heat resistance impact is not influenced by the presence or absence of the liquid crystal layer in the liquid crystal cell since the state of the pressure-sensitive adhesive layer adhered to the glass substrate is observed.

[Industrial applicability]

The liquid crystal panel of the present invention exhibits excellent whiteout prevention property and durability, and is also excellent in workability. Therefore, the liquid crystal display device to which this liquid crystal panel is applied can give a good display quality and maintain the good display quality for a long period of time.

10: Glass cell for liquid crystal display (liquid crystal cell)
10A: long side of glass cell for liquid crystal display
11, 12: transparent glass substrate
20: Polarizing plate (first and second relation)
21: First polarizing plate
21A: absorption axis of the first polarizer plate
22: Second polarizing plate
22A: absorption axis of the second polarizer plate
25: polarizing film
26, 27: transparent protective layer
28: Optical compensation film (retardation film)
29: Interlayer adhesive
30: Spot-on pressure-sensitive adhesive layer (not related to first and second)
31: first pressure-sensitive adhesive layer
32: second pressure-sensitive adhesive layer

Claims (13)

A liquid crystal display glass cell having a rectangular shape,
A first polarizer adhered to one side of the glass cell through a first adhesive layer so that an absorption axis thereof is parallel to long sides of the glass cell;
And a second polarizer plate adhered to the other surface of the glass cell through a second pressure sensitive adhesive layer so that an absorption axis thereof is orthogonal to an absorption axis of the first polarizer plate,
Wherein at least one of the first pressure-sensitive adhesive layer and the second pressure-
(A) (A-1)

(Wherein 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)
80 to 96% by weight of (meth) acrylic acid alkyl ester,
(A-2) a compound represented by the following formula

(Meth) acrylic compound 3 represented by the formula ( ₃ ): wherein R ₃ represents a hydrogen atom or a methyl group, n represents an integer of 1 to 8, and R ₄ represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group) To 15% by weight, and
(A-3) 0.1-5 wt% of an unsaturated monomer having a polar functional group and containing an unsaturated monomer having a free carboxyl group and an unsaturated monomer having a hydroxyl group,
(Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) in the range of from 1 million to 2 million, 100 parts by weight of an acrylic resin having a molecular weight distribution ranging from 3 to 7,
(B) a crosslinking agent in an amount of 0.01 to 5 parts by weight
Wherein the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has a gel fraction of 60 to 99% by weight. The pressure-sensitive adhesive composition according to claim 1, wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are formed together with a pressure-sensitive adhesive composition containing 100 parts by weight of the acrylic resin (A) and 0.01 to 5 parts by weight of the crosslinking agent (B) Wherein the pressure-sensitive adhesive layer formed from the composition has a gel fraction of 60 to 99 wt%. The liquid crystal panel according to claim 1 or 2, wherein the unsaturated monomer (A-3) further comprises an unsaturated monomer having an amino group or an unsaturated monomer having an epoxy ring. The liquid crystal panel according to claim 1 or 2, wherein the crosslinking agent (B) contains an isocyanate compound. The liquid crystal panel according to claim 1 or 2, wherein the pressure-sensitive adhesive composition further comprises 0.03 to 1 part by weight of the silane compound (C). The liquid crystal panel according to claim 1 or 2, wherein the pressure-sensitive adhesive composition further comprises (D) an ionic compound. The liquid crystal panel according to claim 6, wherein the unsaturated monomer (A-2) is an aromatic ring-containing (meth) acrylic compound represented by the formula (II) The liquid crystal panel according to claim 1 or 2, wherein at least one of the first polarizing plate and the second polarizing plate is a protective film / polarizing film / protective film. The retardation film according to claim 8, wherein the retardation film has a retardation value in the plane of 0 to 20 nm and a retardation value in the thickness direction of 20 to 80 nm in thickness and the film positioned on the glass cell for liquid crystal display comprises a cellulose acetate resin having a in-plane retardation value of 30 to 80 nm and a retardation value in the thickness direction of 80 to 250 nm Liquid crystal panel. The retardation film according to claim 8, wherein the retardation film has a retardation value in the plane of 0 to 20 nm and a retardation value in the thickness direction of 20 to 80 nm and the retardation value in the thickness direction of the film is in the range of -25 to 25 nm, the cellulose acylate resin Lt; / RTI &gt; The liquid crystal display device according to claim 8, wherein the film located farther from the liquid crystal display glass cell among the two protective films sandwiching the polarizing film includes a cellulose acetate resin, and the film positioned on the glass cell side for liquid crystal display is a cycloolefin Based resin. The ionic compound (D) according to claim 6, wherein the ionic compound (D)
The following formula III

(Wherein R ₅ to R ₉ each 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), or a pyridinium-
The following formula IV

(Wherein R ₁₁ is an alkyl group having 1 to 12 carbon atoms and R ₁₂ , R ₁₃ and R ₁₄ each independently represents an alkyl group having 6 to 12 carbon atoms) panel. 13. The method according to claim 12, wherein the ionic compound (D)
The pyridinium cations represented by the above formula (III) whose total carbon number is at least 8,
And a quaternary ammonium cation having a total carbon number of 20 or more represented by the formula (IV).

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