KR101713574B1 - Adhesive composition, polarizing plate and liquid crystal display device comprising the same - Google Patents

Abstract

(식 중, R₁ 내지 R₃ 및 X는 명세서에서 정의된 바와 같다).More particularly, the present invention relates to a pressure-sensitive adhesive composition comprising 90 to 99.99% by weight of a (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms and an activity of a nucleophilic addition reaction From 0.01 to 10% by weight of a monomer of the formula (1) having a large phenol group; And a cross-linking agent, it is possible to improve the productivity by shortening the curing period without addition of a separate component, and also to provide a pressure-sensitive adhesive capable of securing sufficient port- A polarizing plate and a liquid crystal display including the same,
[Chemical Formula 1]

(Wherein R ₁ to R ₃ and X are as defined in the specification).

Description

TECHNICAL FIELD [0001] The present invention relates to a pressure-sensitive adhesive composition, a polarizing plate including the same, and a liquid crystal display device using the pressure-

The present invention relates to a pressure-sensitive adhesive composition capable of shortening a curing period without addition of a separate component, having excellent storage stability and light leakage, and a polarizing plate and a liquid crystal display including the same.

2. Description of the Related Art A liquid crystal display device (LCD) includes a liquid crystal cell and a liquid crystal panel including a polarizing plate bonded to both sides of the liquid crystal cell via an adhesive layer.

The adhesive for the bonding of the liquid crystal cell and the polarizing plate should simultaneously satisfy the properties such as adhesiveness to the substrate, light resistance prevention property, heat resistance and anti-wet heat resistance as well as reworkability. In addition, in addition to the above-mentioned physical properties, the pressure-sensitive adhesive is required to shorten the curing period to improve the productivity.

As described above, a method using a crosslinking accelerator that promotes a crosslinking reaction has been proposed as a method for shortening the curing period while maintaining physical properties required as a conventional pressure-sensitive adhesive.

Korean Patent Laid-Open No. 2009-0132116 discloses a pressure-sensitive adhesive composition comprising a Lewis base having a specific structure, and Korean Published Patent Application No. 2008-0047030 discloses a pressure-sensitive adhesive composition comprising Lewis acid. Although the pressure-sensitive adhesive composition described in the above documents has an effect of shortening the curing time, there is a disadvantage that the viscosity of the pressure-sensitive adhesive composition is rapidly changed due to the addition of the crosslinking accelerator, thereby lowering the storage stability and shortening the pot- It may cause problems in stability.

An object of the present invention is to provide a pressure-sensitive adhesive composition which can shorten a curing period without addition of a crosslinking accelerator and can secure excellent storage stability at the same time.

Another object of the present invention is to provide a polarizing plate in which a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition is laminated.

It is another object of the present invention to provide a liquid crystal display device having the polarizing plate on at least one surface of a liquid crystal cell.

1. Copolymer of 90 to 99.99% by weight of a (meth) acrylate monomer having an alkyl group of 1 to 12 carbon atoms and 0.01 to 10% by weight of a monomer of the formula (1); And a crosslinking agent:

(Wherein R ₁ is H or CH ₃ ; R ₂ is H or CH ₃ ; X is S, O or NH; and R ₃ is a hydrocarbon group having 0 to 1 carbon atoms or a phenyl group).

2. The pressure-sensitive adhesive composition according to 1 above, wherein the monomer of formula (1) is obtained by reacting a compound of formula (2) with a compound of formula (3) in the presence of a solvent and a catalyst:

(In the formula, R ₄ is H or CH _3; R ₅ is OH, CH ₂ OH, _{hydroxy-phenyl, SH, CH 2 SH, NH} 2, CH 2 NH 2, CH 2 CH 2 NH 2 or aniline group; R ₆ is ₃ H or CH).

3. The pressure-sensitive adhesive composition according to 1 above, wherein the copolymer has an acid value of 1 mgKOH / g or less.

4. The pressure-sensitive adhesive composition according to 1 above, wherein the monomer of formula (1) is contained in an amount of 0.1 to 6% by weight based on 100% by weight of the copolymer.

5. The pressure-sensitive adhesive composition according to 1 above, wherein the crosslinking agent is at least one selected from the group consisting of an isocyanate compound and an epoxy compound.

6. A polarizing plate laminated with a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to any one of 1 to 5 above.

7. A liquid crystal display device comprising a liquid crystal cell provided with a polarizing plate on at least one side thereof.

The pressure-sensitive adhesive composition according to the present invention can improve the productivity by shortening the curing period by directly applying a phenolic group-containing monomer having a high nucleophilic addition activity in the molecule to the copolymer while maintaining the physical properties required as a conventional pressure- But the viscosity change is suppressed, the storage stability is excellent, sufficient port-life can be secured, and the process stability can be improved.

In addition, the pressure sensitive adhesive composition of the present invention can further improve the light leakage phenomenon by increasing the photoelastic coefficient without addition of a separate component.

The present invention relates to a pressure-sensitive adhesive composition capable of shortening a curing period without addition of a separate component, having excellent storage stability and light leakage, and a polarizing plate and a liquid crystal display including the same.

Hereinafter, the present invention will be described in detail.

The pressure-sensitive adhesive composition of the present invention comprises a copolymer of 90 to 99.99% by weight of a (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms and 0.01 to 10% by weight of a monomer of the formula (1); And a crosslinking agent.

[Chemical Formula 1]

(Wherein R ₁ is H or CH ₃ ; R ₂ is H or CH ₃ ; X is S, O or NH; and R ₃ is a hydrocarbon group having 0 to 1 carbon atoms or a phenyl group).

The copolymer of the present invention is characterized in that an aromatic functional group, particularly a phenol group-containing monomer having a large nucleophilic addition reaction activity in the molecule is copolymerized.

The copolymer is preferably an acrylic copolymer in which a (meth) acrylate monomer having an alkyl group of 1-12 carbon atoms and an aromatic carboxylic acid group are copolymerized as a pressure-sensitive adhesive resin. Here, (meth) acrylate means both acrylate and methacrylate.

Butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (Meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (Meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate and lauryl (meth) acrylate. These may be used singly or in combination of two or more. Of these, n-butyl acrylate, 2-ethylhexyl acrylate or a mixture thereof is preferable.

The (meth) acrylate monomer having an alkyl group having from 1 to 12 carbon atoms is preferably contained in an amount of 90 to 99.99% by weight, more preferably 95 to 99.95% by weight based on 100% by weight of the total monomers used in the production of the copolymer, . When the content is less than 90% by weight, the adhesive strength is not sufficient, and when the content is more than 99.99% by weight, the cohesive strength may be lowered.

The monomer of the formula (1) is a monomer having a phenolic group, which is an aromatic functional group having a high nucleophilic addition activity in the molecule. It accelerates the reaction between the copolymer and the following crosslinking agent to shorten the curing period and increase the photoelastic coefficient, The ingredients are:

[Chemical Formula 1]

(Wherein R ₁ is H or CH ₃ ; R ₂ is H or CH ₃ ; X is S, O or NH; and R ₃ is a hydrocarbon group having 0 to 1 carbon atoms or a phenyl group).

The monomer of formula (1) may be obtained, for example, by reacting a compound of formula (2) with a compound of formula (3) in the presence of a solvent and a catalyst:

(2)

,

,

(3)

(In the formula, R ₄ is H or CH _3; R ₅ is OH, CH ₂ OH, _{hydroxy-phenyl, SH, CH 2 SH, NH} 2, CH 2 NH 2, CH 2 CH 2 NH 2 or aniline group; R ₆ is ₃ H or CH).

Examples of the compound represented by the formula (2) include those represented by the following formulas (2a) to (2e).

(2a)

(2b)

[Chemical Formula 2c]

(2d)

[Formula 2e]

Examples of the compound of formula (3) include acryloyl chloride or methacryloyl chloride.

The solvent is not limited as long as it is an organic solvent used in ordinary synthesis, and examples thereof include tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, dichloromethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, iso Propyl alcohol, etc. These may be used alone or in admixture of two or more.

As the catalyst, a catalyst known in synthesis can be used, and organic tin compounds such as dibutyl tin acetylacetonate, dibutyl tin dilaurate, dioctyl tin dilaurate, dibutyl tin octoate and the like; Iron compounds such as iron acetylacetonate and ferric chloride; And tertiary amine catalysts such as triethylamine and triethylenediamine. These catalysts may be used alone or in combination of two or more.

The monomer represented by the formula (1) is preferably 4-acryloyloxybenzoic acid represented by the following formula (4).

[Chemical Formula 4]

The monomer of the formula (1) is preferably contained in an amount of 0.01 to 10% by weight, more preferably 0.1 to 6% by weight, based on 100% by weight of the total monomers used in the production of the copolymer. When the content is less than 0.01% by weight, the effect of accelerating the crosslinking reaction may be insignificant and the cohesive force may be deteriorated. When the content is more than 10% by weight, the viscosity change may become large, resulting in poor storage stability and adherence.

The copolymer may further contain other polymerizable monomers other than the above monomers in a range that does not lower the adhesive force, for example, 10% by weight or less.

The method for producing the copolymer is not particularly limited and can be produced by methods such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization, which are commonly used in the art, and solution polymerization is preferable. In addition, a solvent, a polymerization initiator, a chain transfer agent for molecular weight control and the like which are usually used in polymerization can be used.

The copolymer usually has a weight average molecular weight (in terms of polystyrene) measured by gel permeation chromatography (GPC) of usually 50,000 to 2,000,000, preferably 1,000,000 to 2,000,000.

The copolymer of the present invention constituted as described above is obtained by copolymerizing a monomer containing a phenolic group, which is an aromatic functional group having a high nucleophilic addition activity in a molecule, and can itself shorten the curing period due to high reactivity, It can also improve the light leakage phenomenon. Further, even when the acid value is not more than 1 mgKOH / g, that is, the acid value-containing copolymer does not contain a carboxyl group (-COOH) as an essential component, the self-reactive property is good, and the curing period can be effectively shortened.

The crosslinking agent is a component for reinforcing the cohesive force of the pressure-sensitive adhesive by properly crosslinking the copolymer, and the kind thereof is not particularly limited. Examples thereof include isocyanate compounds and epoxy compounds, which may be used alone or in combination of two or more.

Examples of the isocyanate compound include tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate , Diisocyanate compounds such as naphthalene diisocyanate; An adduct obtained by reacting 3 moles of a diisocyanate compound with 1 mole of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate compound in which 3 moles of a diisocyanate compound is self-condensed, a diisocyanate obtained from 2 moles of 3 moles of a diisocyanate compound And multifunctional isocyanate compounds containing three functional groups such as burette, triphenylmethane triisocyanate and methylene bistriisocyanate in which the remaining one mole of diisocyanate is condensed in urea.

Examples of the epoxy compound include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, poly Propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl Ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcinol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, trimethylol propane triglycidyl ether, penta Erythritol polyglycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) iso (N, N-glycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl-m - xylylenediamine, and the like.

The crosslinking agent is preferably contained in an amount of 0.01 to 15 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the copolymer based on the solid content. If the content is less than 0.01 part by weight, the cohesive force becomes small due to insufficient crosslinking, resulting in deterioration of durability such as lifting and deterioration of cutability. If the content is more than 15 parts by weight, light leakage may occur due to excessive crosslinking reaction.

Further, the pressure-sensitive adhesive composition may further include a silane coupling agent.

The kind of the silane coupling agent is not particularly limited, and examples thereof include vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- 3-glycidoxypropyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, Acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane , N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) Methyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3- Dimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatepropyltriethoxysilane, and the like. These may be used alone or in combination of two or more.

The silane coupling agent may be contained in an amount of 0 to 10 parts by weight, preferably 0.005 to 5 parts by weight, based on 100 parts by weight of the copolymer based on the solid content. If the content exceeds 10 parts by weight, the durability may be lowered.

In addition to the above-mentioned components, the pressure-sensitive adhesive composition may further contain additives such as a tackifier resin, an antioxidant, a corrosion inhibitor, a leveling agent, a surface lubricant, an antioxidant, , A dye, a pigment, a defoaming agent, a filler, a light stabilizer, an antistatic agent, and the like.

The pressure-sensitive adhesive composition thus constituted contains a copolymer copolymerized with a monomer containing a phenolic group, which is an aromatic functional group, in the molecule while maintaining the physical properties required as a pressure-sensitive adhesive in the prior art, The period can be shortened and the photoelastic coefficient can be increased to further improve the light leakage phenomenon. In addition, since no additional components are added, the storage stability can be improved and the process stability can be enhanced.

The pressure-sensitive adhesive composition of the present invention can be used not only as a pressure-sensitive adhesive for a polarizing plate for bonding with a liquid crystal cell but also as a pressure-sensitive adhesive for a surface protective film. In addition, it can be used not only as a protective film, a reflective sheet, a structural adhesive sheet, a photographic adhesive sheet, a lane marking adhesive sheet, an optical adhesive product, an electronic component adhesive, but also a general commercial adhesive sheet product or a medical patch.

The polarizing plate of the present invention is characterized in that a pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive composition is laminated.

The thickness of the pressure-sensitive adhesive layer can be adjusted in accordance with the adhesive strength, and is preferably 3 to 100 탆, more preferably 10 to 100 탆.

Such a polarizing plate can be applied to all conventional liquid crystal display devices, and specifically a liquid crystal display device including a liquid crystal panel in which a polarizing plate in which a pressure-sensitive adhesive layer is laminated is provided on at least one surface of a liquid crystal cell.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Example

Synthesis Example 1 Synthesis of 4-acryloylaminophenol

A round bottom flask (1 L) was immersed in an ice bath at 0 ° C., and 100 g of 4-aminophenol and 300 g of a dichloromethane solvent were added and stirred for 30 minutes. 50 g of acryloyl chloride was slowly added thereto in a dropwise manner over 10 minutes. Subsequently, 100 g of triethylamine was added dropwise over 30 minutes, further stirred at room temperature for 30 minutes, then 500 ml of distilled water was added and stirred for 10 minutes. After completion of the stirring, the dichloromethane solvent layer was separated using a separating funnel and the solvent was removed by vacuum distillation to obtain 4-acryloylaminophenol (4-AAP) represented by the formula (4).

The NMR analysis results of the obtained compound are as follows.

_{^{1 H NMR (200㎒, CDCl 3}} ), 5.04 (s, OH), 5.64 (t, CH), 6.17 (t, CH), 6.65 (t, CH), 6.75 (d, CH), 7.53 (d, CH), 8.23 (s, NH).

[Chemical Formula 4]

Synthesis Example 2. Synthesis of 4-acryloyloxyphenol

Acryloyloxyphenol (4-AOP) of formula (5) was obtained by using 4-hydroxyphenol in place of 4-aminophenol.

The NMR analysis results of the obtained compound are as follows:

_{^{1 H NMR (200㎒, CDCl 3}} ), 5.17 (s, OH), 5.84 (t, CH), 6.03 (t, CH), 6.25 (t, CH), 6.75 (d, CH), 6.93 (d, CH).

[Chemical Formula 5]

Production Example 1. Preparation of Acrylic Copolymer A

95 parts by weight of n-butyl acrylate (BA) and 5 parts by weight of 4-acryloylaminophenol (4-AAP) obtained in Synthesis Example 1 were added to a 1 L reactor equipped with a cooling device for regulating the temperature of the nitrogen gas, And 100 parts by weight of ethyl acetate (EA) was added as a solvent. Thereafter, a nitrogen gas was poured in for 1 hour to remove oxygen, and the temperature was maintained at 62 ° C. After uniformly stirring the monomer mixture, 0.07 part by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to prepare an acrylic copolymer A having a weight average molecular weight of 80,000 or more.

Production Example 2-5. Production of acrylic copolymer B-E

A monomer mixture as shown in Table 1 below was used in the same manner as in Preparation Example 1,

division designation Monomer (parts by weight) BA 4-AAP 4-AOP AA Production Example 1 A 95 5 - - Production Example 2 B 99.95 0.05 - - Production Example 3 C 92 8 - - Production Example 4 D 95 - 5 - Production Example 5 E 95 - - 5 BA: n-butyl acrylate
4-AAP: 4-acryloylaminophenol
4-AOP: 4-acryloyloxyphenol
AA: Acrylic acid

Example 1

(1) Pressure-sensitive adhesive composition

Based on the solid content, 100 parts by weight of the acrylic copolymer A prepared in Preparation Example 1, 0.5 part by weight of a hexamethylene diisocyanate adduct of trimethylolpropane (COR-HXR, manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent, And 0.3 part by weight of 3-glycidoxypropyltrimethoxysilane (KBM-403, Shin-Etsu) were mixed and diluted to an appropriate concentration in consideration of coating property to prepare a pressure-sensitive adhesive composition.

(2) Pressure-sensitive adhesive sheet

The pressure-sensitive adhesive composition thus prepared was dried on a film coated with silicone release agent, and then applied to a thickness of 25 탆 and dried at 100 캜 for 1 minute to form a pressure-sensitive adhesive layer. And another layer of release film was laminated thereon to produce a pressure-sensitive adhesive sheet.

(3) Polarizer with adhesive

The releasing film of the pressure-sensitive adhesive sheet thus prepared was peeled off, and a pressure-sensitive adhesive layer was laminated on an iodine-based polarizing plate having a thickness of 185 μm to produce a polarizing plate with a pressure-sensitive adhesive. The prepared polarizing plate was stored for a curing period under conditions of 23 캜 and 55% RH.

Example 2

The acrylic copolymer B prepared in Preparation Example 2 was used in the same manner as in Example 1.

Example 3

The acrylic copolymer C prepared in Preparation Example 3 was used in the same manner as in Example 1.

Example 4

The acrylic copolymer D prepared in Preparation Example 4 was used in the same manner as in Example 1.

Comparative Example 1

The acrylic copolymer E prepared in Preparation Example 5 was used in the same manner as in Example 1.

Comparative Example 2

The acrylic copolymer E prepared in Preparation Example 5 was used in the same manner as in Example 1 except that 0.1 parts by weight of dibutyltin dilaurate was used as a crosslinking accelerator.

Test Example

The properties of the pressure-sensitive adhesive composition, the pressure-sensitive adhesive sheet and the polarizer with a pressure-sensitive adhesive prepared in Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 2 below.

1. Storage stability (viscosity change,%)

The initial viscosity of the pressure-sensitive adhesive composition thus prepared and the viscosity after standing at room temperature for 24 hours were measured using a viscosity meter (Brookfield LVDV-II + type B (spindle no. 3, 30 rpm)). The rate of change (? Eta) of the measured viscosity was calculated. At this time, when the viscosity change (?) Was 20% or less, it was judged that the storage stability was excellent.

2. Curing period

The adhesive sheet thus prepared was cured for 1 to 10 days at 23 DEG C and 65% RH, and the gel fraction was measured in the following manner for each day, and the curing period was measured, in which the gel fraction was no longer increased.

Approximately 0.25 g of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is attached to a wire mesh (100 mm x 100 mm) of a 250 mesh precisely weighed, and the gel is wrapped so as not to leak. After accurately weighing the weight with a precision balance, the wire net is immersed in the ethyl acetate solution for 3 days. The immersed wire mesh is taken out, washed with a small amount of ethyl acetate solution, dried at 120 ° C for 24 hours and then weighed. Using the measured weight, the gel fraction was calculated by the following equation (1).

B is the weight of the wire netting attached to the pressure-sensitive adhesive layer (BA: weight of the pressure-sensitive adhesive, g); C is the weight of the wire netted after immersion (CA: weight of the gelled resin, g )being].

3. Light leakage phenomenon

The prepared polarizer with a pressure-sensitive adhesive was bonded to both sides of a glass substrate (# 1737, Corning Inc.), and autoclaved for 30 minutes at a temperature of 5 ° C and a pressure of 5 atm. The prepared specimens were allowed to stand in an oven at 80 ° C for 24 hours, and then placed in a dark room on the backlight as soon as they were taken out. The specimens were photographed to visually confirm the degree of light leakage and evaluated according to the following criteria.

<Evaluation Criteria>

○: It is difficult to visually identify the light leakage phenomenon.

△: Light leakage phenomenon is somewhat present.

×: Light leakage phenomenon is clearly identified.

division ? (%) Curing period (days) Light leakage phenomenon Example 1 5 2 ○ Example 2 One 3 △ Example 3 9 One ○ Example 4 6 2 ○ Comparative Example 1 4 4 × Comparative Example 2 200 One ×

As shown in Table 2, the pressure-sensitive adhesive compositions of Examples 1 to 4, in which the acrylic copolymer copolymerized with the monomer having a phenolic group in the molecule and the crosslinking agent, according to the present invention had storage stability And it was confirmed that not only the curing period was shortened but also the light leakage phenomenon was improved. In particular, when 0.1 to 6% by weight of a monomer having a phenol group is contained in the acrylic copolymer, a better effect is obtained in terms of all properties, which is preferable.

Claims (7)

A copolymer of 90 to 99.99% by weight of a (meth) acrylate monomer having an alkyl group of 1 to 12 carbon atoms and 0.01 to 10% by weight of a monomer of the formula (1); And
A pressure-sensitive adhesive composition comprising a crosslinking agent:
[Chemical Formula 1]

(Wherein R ₁ is H or CH ₃ ; R ₂ is H or CH ₃ ; X is S, O or NH; and R ₃ is a hydrocarbon group having 0 to 1 carbon atoms or a phenyl group).
The pressure-sensitive adhesive composition according to claim 1, wherein the monomer of formula (1) is obtained by reacting a compound of formula (2) with a compound of formula (3) in the presence of a solvent and a catalyst:
(2)

,
(3)

(In the formula, R ₄ is H or CH _3; R ₅ is OH, CH ₂ OH, _{hydroxy-phenyl, SH, CH 2 SH, NH} 2, CH 2 NH 2, CH 2 CH 2 NH 2 or aniline group; R ₆ is ₃ H or CH).
The pressure-sensitive adhesive composition according to claim 1, wherein the copolymer has an acid value of 1 mgKOH / g or less.
The pressure-sensitive adhesive composition according to claim 1, wherein the monomer of formula (1) is contained in an amount of 0.1 to 6% by weight based on 100% by weight of the copolymer.
The pressure-sensitive adhesive composition according to claim 1, wherein the crosslinking agent is at least one selected from the group consisting of an isocyanate compound and an epoxy compound.
A polarizer comprising a pressure-sensitive adhesive composition layered with the pressure-sensitive adhesive composition according to any one of claims 1 to 5.
The liquid crystal display device according to claim 6, wherein at least one surface of the liquid crystal cell is provided with the polarizing plate.