KR20140140872A - Acrylic copolmer and adhesive composition containing threrof - Google Patents

Abstract

The present invention relates to an acryl-based copolymer and an adhesive composition containing the same. More specifically, the acryl-based copolymer including a compound of chemical formula 1 or chemical formula 2 and an acryl-based monomer including hydroxyl groups is used for the adhesive composition. Therefore, the adhesive composition can have increased productivity resulted from reduced time for being cured; has storage stability resulted from inhibited change of viscosity; and can have durability and re-workability at the same time.

Description

TECHNICAL FIELD [0001] The present invention relates to an acrylic copolymer, and a pressure-sensitive adhesive composition containing the same. BACKGROUND ART [0002]

The present invention relates to a pressure-sensitive adhesive composition having a shortened curing period and excellent durability and reworkability.

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 pressure-sensitive adhesive should simultaneously satisfy not only adhesiveness to a substrate, light resistance, heat resistance and durability but also physical properties such as reworkability. In addition, the pressure-sensitive adhesive along with the physical properties is required to shorten the curing period and improve the productivity.

As a conventional method for shortening the curing period while maintaining physical properties required as a pressure-sensitive adhesive, Korean Patent Laid-Open Publication No. 2011-0056250 discloses a pressure-sensitive adhesive composition using a hydroxy group-containing acrylamide monomer as a crosslinking monomer.

The pressure-sensitive adhesive composition has a curing period of about 24 hours. However, in order to improve the productivity of the polarizing plate, the curing process for 24 hours is never shortened because the process is carried out with the aim of shipment per day. In addition, when the curing period is less than 24 hours, it is impossible to secure physical properties such as durability and reworkability, which makes it difficult to apply as a pressure sensitive adhesive for a polarizing plate.

An object of the present invention is to provide a pressure-sensitive adhesive composition which can shorten a curing period to 24 hours or less without addition of a separate crosslinking accelerator, and can satisfy physical properties required as a pressure-sensitive adhesive.

In order to achieve the above object, the present invention provides an acrylic copolymer containing a compound of the following general formula (1) or (2) and an acrylic monomer containing a hydroxyl group.

Wherein R ₁ is hydrogen or a methyl group, X is O or NH, and R ₂ is a straight or branched chain aliphatic hydrocarbon group having 1-12 carbon atoms, and the aliphatic hydrocarbon group includes N or O in the main chain And R ₃ and R ₄ are each independently selected from the group consisting of hydrogen, halogen, -OR ₅ , -N (R ₅ ) ₂ , -SR ₅ , -CN, -NO ₂ or An aliphatic hydrocarbon having 1 to 12 carbon atoms and R ₅ is an aliphatic hydrocarbon having 1 to 12 carbon atoms)

Preferably, wherein the compound of formula 1 or 2, R ₁ is hydrogen or methyl, X is oxygen, R ₂ has carbon atoms containing an ether, ester or urethane in the main chain and the side chain containing the -OH or hydrogen And R < ₃ > and R < ₄ > may each independently be hydrogen.

The compound of Formula 1 or Formula 2 may be at least one compound selected from the group consisting of the following Formulas 3 to 5.

The acrylic copolymer may contain a (meth) acrylate monomer having an alkyl group having 4 to 12 carbon atoms, a compound having the formula (1) or (2), and a monomer having a hydroxyl group.

The compound of Formula 1 or Formula 2 may contain 0.1 to 10 parts by weight based on 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 4-12 carbon atoms.

The present invention also provides a pressure-sensitive adhesive composition containing the acrylic copolymer.

The pressure-sensitive adhesive composition may further contain a crosslinking agent.

The pressure-sensitive adhesive composition of the present invention has an advantage that the curing period can be shortened to 24 hours or less without addition of a separate crosslinking accelerator, and satisfactory physical properties (storage stability, durability, and workability) required as a pressure-sensitive adhesive .

The present invention relates to a pressure-sensitive adhesive composition which is shortened in curing time by using an acrylic copolymer containing a novel acrylate-based compound and is excellent in durability and reworkability.

Hereinafter, the present invention will be described in detail.

The acrylic copolymer of the present invention contains a compound represented by the following general formula (1) or (2).

[Chemical Formula 1]

(2)

Wherein R ₁ is hydrogen or a methyl group, X is O or NH, and R ₂ is a straight or branched chain aliphatic hydrocarbon group having 1-12 carbon atoms, and the aliphatic hydrocarbon group includes N or O in the main chain And R ₃ and R ₄ are each independently selected from the group consisting of hydrogen, halogen, -OR ₅ , -N (R ₅ ) ₂ , -SR ₅ , -CN, -NO ₂ or An aliphatic hydrocarbon having 1 to 12 carbon atoms and R ₅ is an aliphatic hydrocarbon having 1 to 12 carbon atoms)

Preferably the compounds of the formula (I) or (II) R ₁ is hydrogen or methyl, X is oxygen, R ₂ is a 1-carbon atoms containing an ether, ester or urethane in the main chain and the side chain containing the -OH or hydrogen Lt; ₃ > and R < ₄ > are each independently hydrogen.

More preferably, the compound of formula (1) or (2) may be at least one compound selected from the group consisting of the following formulas (3) to (5)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

The acrylic copolymer of the present invention preferably contains a (meth) acrylate monomer having an alkyl group having 4 to 12 carbon atoms and a compound represented by the above formula (1). Here, (meth) acrylate means acrylate and methacrylate.

The compound of Formula 1 or 2 acts as a basic catalyst in the molecule to improve the crosslinking reactivity between the crosslinking agent and the crosslinkable monomer with an acrylic copolymer containing an amine so that the curing period is shortened without any additional components such as a crosslinking accelerator .

Specifically, it is immobilized on the copolymer in a solution state, and it is difficult to interact with the crosslinking agent, so stability of the liquid solution can be easily ensured. After the coating and drying, the reaction with the crosslinking monomer and the crosslinking agent is promoted to shorten curing.

Further, the compound of the above formula (1) or (2) affects the form of crosslinking and contributes to enhance cohesion in the pressure-sensitive adhesive, so that durability and reworkability can be improved.

Examples of the alkyl (meth) acrylate monomer having 4 to 12 carbon atoms include (meth) acrylates derived from aliphatic alcohols having 4 to 12 carbon atoms such as n-butyl (meth) acrylate, Octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isopropyl (meth) acrylate, (Meth) acrylate, etc. These may be used alone or in combination of two or more. Of these, n-butyl acrylate, 2-ethylhexyl acrylate or a mixture thereof is preferable.

The compound of formula (1) or (2) may contain 0.1 to 10 parts by weight, preferably 0.1 to 7 parts by weight, based on 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 4-12 carbon atoms. If the content is less than 0.1 part by weight, the effect of accelerating the crosslinking reaction is insignificant and it may be difficult to expect a shortening effect of the curing period and an improvement in durability. When the content exceeds 10 parts by weight, the crosslinking reaction becomes excessively rapid, which may cause problems in the stability of the composition, and the peeling force of the adhesive force becomes large, so that the pressure-sensitive adhesive may remain on the substrate during reworking.

Examples of the monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl Hydroxypropyleneglycol (meth) acrylate, hydroxyalkylene glycol having 2 to 4 carbon atoms in the alkylene group (e.g., methoxyethyl (meth) acrylate, Hydroxybutyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxynonyl (meth) acrylate, 4-hydroxybutyl vinyl ether, Vinyl ether, and 10-hydroxydecyl vinyl ether. Of these, 4-hydroxybutyl vinyl ether is preferable.

The monomer having a hydroxyl group may be contained in an amount of 0.1 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 4 to 12 carbon atoms. When the content is less than 0.1 parts by weight, cohesion is insufficient and bubbles may be generated under heat-resistant conditions. When the content is more than 5 parts by weight, the adhesive strength is reduced due to excessive crosslinking, and peeling failure may occur under heat-resistant conditions.

The acrylic copolymer of the present invention may further contain a polymerizable monomer having a crosslinkable functional group in addition to the crosslinkable functional group by the compound of the above formula (1) or (2). The polymerizable monomer has a function of imparting cohesive strength or adhesive strength by chemical bonding with the following crosslinking agent, and examples thereof include a monomer having a carboxyl group, a monomer having an amide group, and a monomer having a tertiary amine group. These may be used alone or in combination of two or more.

Examples of the monomer having an amide group include (meth) acrylamide, N-isopropyl acrylamide, N-tertiary butyl acrylamide, 3-hydroxypropyl (meth) acrylamide, 4-hydroxybutyl (Meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide and 2-hydroxyethylhexyl (meth) acrylamide. Of these, (meth) acrylamide is preferable.

Examples of the monomer having a tertiary amine group include N, N- (dimethylamino) ethyl (meth) acrylate, N, N- (diethylamino) ethyl (meth) ) Acrylate, and the like. Examples of the monomer having a carboxyl group include monovalent acids such as (meth) acrylic acid and crotonic acid; Dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid, and monoalkyl esters thereof; 3- (meth) acryloylpropionic acid; A succinic anhydride ring-opening addition adduct of 2-hydroxyalkyl (meth) acrylate in which the alkyl group has 2 to 4 carbon atoms, anhydrous succinic ring opening adduct of a hydroxyalkylene glycol (meth) acrylate having 2 to 4 carbon atoms in the alkylene group , Compounds obtained by ring-opening addition of succinic anhydride to caprolactone adducts of 2-hydroxyalkyl (meth) acrylates whose alkyl groups have 2-3 carbon atoms, and among these, (meth) acrylic acid is preferable.

The polymerizable monomer is preferably contained in an amount of 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, based on 100 parts by weight of the total monomers used in the production of the acrylic copolymer. When the content is less than 0.05 part by weight, the cohesive force of the pressure-sensitive adhesive becomes small and durability may be deteriorated. When the content is more than 10 parts by weight, a high gel fraction may lower the adhesive strength and cause durability problems.

In addition, other polymerizable monomers other than the above-mentioned monomers may be further added in an amount not lowering the adhesive force, for example, 10 parts by weight or less based on 100 parts by weight of the total monomers used in the production of the acrylic copolymer.

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 preferably has a weight average molecular weight (polystyrene conversion, Mw) of 50,000 to 2,000,000, preferably 400,000 to 2,000,000 as measured by gel permeation chromatography (GPC). If the weight-average molecular weight is less than 50,000, cohesion between co-polymers may be insufficient, which may cause problems in adhesion durability. If the weight average molecular weight is more than 2,000,000, a large amount of diluting solvent may be required in order to ensure fairness in coating.

Further, the present invention is characterized by a pressure-sensitive adhesive composition containing the acrylic copolymer. The pressure-sensitive adhesive composition may further contain a crosslinking agent.

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, polypropylene glycol Hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, glycerol diglycidyl ether, glycerol diglycidyl ether, Diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcinol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, trimethylol propane triglycidyl ether, pentaerythritol Polyglycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanurate N, N ', N'-tetraglycidyl-m-glycidoxyethyl isocyanurate, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, Xylylenediamine, and the like.

In addition, an isocyanate compound, an epoxy compound, and a melamine compound may be used alone or in admixture of two or more.

Examples of the melamine-based compound include hexamethylol melamine, hexamethoxymethyl melamine, and hexabutoxymethyl melamine.

The crosslinking agent is preferably contained in an amount of 0.1 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. When the content is less than 0.1 parts by weight, the cohesive force becomes small due to insufficient crosslinking, resulting in deterioration of durability such as peeling and deterioration of cutability. If the content is more than 15 parts by weight, excessive crosslinking reaction may cause a problem of relaxation of residual stress have.

In addition, the pressure-sensitive adhesive composition of the present invention may further comprise 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 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.

Example  1: Production of acrylic copolymer

Example  1-1

2중량부, 히드록시부틸아크릴레이트(HBA) 2중량부로 이루어진 단량체 혼합물을 투입한 후 용매로 에틸아세테이트(EA) 100중량부를 투입하였다. 그 후 산소를 제거하기 위하여 질소가스를 1 시간 동안 투입하여 치환시킨 후 온도를 80℃로 유지하였다. 단량체 혼합물을 균일하게 교반한 후 반응개시제로 아조비스이소부티로니트릴(AIBN) 0.07중량부를 투입하고 8시간 동안 반응시켜 중량평균분자량이 80만 이상인 아크릴계 공중합체(A-1)를 제조하였다.
88 parts by weight of n-butyl acrylate (BA), 8 parts by weight of benzyl methacrylate (BzMA), 1 part by weight of benzyl methacrylate (BzMA) were added to a 1 L reactor equipped with a cooling device,

, 2 parts by weight of hydroxybutyl acrylate (HBA), and then 100 parts by weight of ethyl acetate (EA) was added as a solvent. After that, nitrogen gas was poured in for 1 hour to remove oxygen, and the temperature was maintained at 80 ° C. After homogeneously stirring the monomer mixture, 0.07 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was added and reacted for 8 hours to prepare an acrylic copolymer (A-1) having a weight average molecular weight of 80,000 or more.

Example  1-2 to 1-8 and Comparative Example  1-6

An acrylic copolymer was prepared in the same manner as in Preparation Example 1, except that the composition of the following Table 1 was used.

division
(Parts by weight) BA BzMA The Crosslinkable monomer 3 4 5 HBA HEA HEAA AA AM Example 1-1 88 8 2 - - 2 - - - - Examples 1-2 88 8 2 - - - 2 - - - Example 1-3 85 8 5 - - 2 - - - - Examples 1-4 83 8 7 - - 2 - - - - Examples 1-5 80 8 10 - - 2 - - - - Examples 1-6 75 8 15 - - 2 - - - - Examples 1-7 88 8 - 2 - 2 - - - - Examples 1-8 88 8 - - 2 2 - - - - Comparative Example 1 90 8 - - - 2 - - - - Comparative Example 2 90 8 - - - - 2 - - - Comparative Example 3 90 8 - - - - - 2 - - Comparative Example 4 90 8 - - - - - - 2 - Comparative Example 5 90 8 - - - - - - - 2 Comparative Example 6 90 8 - - - 2 - - - 2

화학식 4:

화학식 5:

BA: butyl acrylate
BzMA: Benzyl methacrylate
HEA: hydroxyethyl acrylate
HBA: hydroxybutyl acrylate
HEAA: Hydroxyacrylamide
AM: Acrylamide
AA: Acrylic acid
(3)

(4)

(5)

Example  2-1 to 2-11 and Comparative Example  7 to 13

The ingredients were mixed in the composition shown in Table 2, and then diluted with ethyl acetate to prepare a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition prepared above was applied on a release film coated with silicone release agent to a thickness of 25 탆 and dried at 100 캜 for 1 minute to form an adhesive layer.

The pressure-sensitive adhesive layer prepared above was laminated to an iodine-based polarizing plate having a thickness of 185 μm by pressure-sensitive adhesive processing to produce a polarizer with a pressure-sensitive adhesive.

division
(Parts by weight) Acrylic copolymer
(100 parts by weight) Cross-linking agent Silane
Coupling agent Bridging
accelerant A-1 A-2 A-3 A-4 Example 2-1 Example 1-1 0.5 - - - 0.2 - Example 2-2 Examples 1-2 0.5 - - - 0.2 - Example 2-3 Example 1-3 0.5 - - - 0.2 - Examples 2-4 Examples 1-4 0.5 - - - 0.2 - Example 2-5 Examples 1-5 0.5 - - - 0.2 - Examples 2-6 Examples 1-6 0.5 - - - 0.2 - Examples 2-7 Example 1-1 - 0.5 - - 0.2 - Examples 2-8 Example 1-1 - - 0.5 - 0.2 - Examples 2-9 Example 1-1 - - - 0.5 0.2 - Examples 2-10 Examples 1-7 0.5 - - - 0.2 - Examples 2-11 Examples 1-8 0.5 - - - 0.2 - Comparative Example 7 Comparative Example 1 0.5 - - - 0.2 - Comparative Example 8 Comparative Example 2 0.5 - - - 0.2 - Comparative Example 9 Comparative Example 3 0.5 - - - 0.2 - Comparative Example 10 Comparative Example 4 0.5 - - - 0.2 - Comparative Example 11 Comparative Example 5 0.5 - - - 0.2 - Comparative Example 12 Comparative Example 6 0.5 - - - 0.2 - Comparative Example 13 Comparative Example 1 0.5 - - - 0.2 0.1 A-1; Coronate-L (TDI TMP Adduct, Japan Urethane Co., Ltd.)
A-2; Coronate-HXR (isocyanurate of HDI, Urethane Company of Japan)
A-3: D110N (HDI-TMP adduct, Mitsui Chemicals)
A-4: D140N (IPDI-TMP adduct, Mitsui Chemicals)
Silane coupling agent: 3-glycidoxypropyltrimethoxysilane, KBM-403 product, Shin-Etsu Co., Ltd.
Crosslinking accelerator: DBTDLA, dibutyl tin dilaurate

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 the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 3 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 + B type (spindle no. 3, 30 rpm)), Respectively.

<Evaluation Criteria>

?:?? &Lt; 10%

?: 10%??? <20%

×: 20% ≤Δη

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). The curing period was determined on the basis of the time when the calculated gel fraction was included in the range of 70 to 80% and there was no change with time.

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. Durability (heat resistance, Wet heat )

The prepared polarizer with a pressure-sensitive adhesive was cut into a size of 90 mm × 170 mm, and the release film was peeled off. Then, the optical absorption axis was perpendicularly attached to both sides of the glass substrate (110 mm × 190 mm × 0.7 mm). At this time, the applied pressure was 5 kg / cm &lt; 2 &gt;, and the clean room operation was performed so that bubbles or foreign matter would not occur. The heat resistance characteristics were evaluated by observing the occurrence of bubbles or peeling after being left at a temperature of 80 ° C. for 1000 hours. The moisture resistance characteristics were evaluated by observing the occurrence of bubbles or peeling after being left at a temperature of 60 ° C. and 90% RH for 1000 hours Respectively. At this time, the sample was allowed to stand at room temperature for 24 hours immediately before evaluating the state of the specimen.

<Evaluation Criteria>

Ⓞ: No bubbles or peeling.

○: Bubbles or peeling <5

?: 5 pieces? Bubbles or peeling <10 pieces

X: 10 pieces &lt; bubble &

4. Re-workability

The prepared polarizing plate with a pressure-sensitive adhesive was cut into a size of 25 mm x 100 mm, the release film was peeled off, laminated to a glass substrate (# 1737, Corning) at a pressure of 0.25 MPa, The sample was autoclaved. The heat resistance of the specimens was measured at room temperature for 120 hours and then peeled off at a rate of 1.3 cm / sec. The heat resistance of the specimens was measured at 60 ℃, The sample was stored in an oven at 90% RH for 12 hours, taken out and allowed to stand at room temperature for 120 hours, peeled off at the same rate, and evaluated according to the following criteria.

<Evaluation Criteria>

○: No adhesive residue is left on the glass substrate in both heat resistance and anti-wet heat resistance, and the polarizer is cleanly peeled without tearing.

?: A small amount of a pressure-sensitive adhesive remained on the glass substrate at any one or more of heat resistance and anti-wet heat resistance, and the polarizer was cleanly peeled without tearing.

X: A large amount of adhesive is left on the glass substrate or the polarizer tears in the peeling process in at least one of heat resistance and anti-wet heat resistance.

division Storage stability Curing period durability Re-workability Heat resistance Wet heat Example 2-1 ○ 24 hours ○ ○ ○ Example 2-2 ○ 24 hours ○ ○ ○ Example 2-3 ○ 18 hours ○ ○ ○ Examples 2-4 ○ 12 hours ○ ○ ○ Example 2-5 △ 8 hours ○ ○ ○ Examples 2-6 △ 6 hours ○ ○ ○ Examples 2-7 ○ 24 hours △ ○ ○ Examples 2-8 ○ 24 hours △ ○ ○ Examples 2-9 ○ 24 hours △ ○ ○ Examples 2-10 ○ 24 hours ○ ○ ○ Examples 2-11 ○ 24 hours ○ ○ ○ Comparative Example 7 ○ 5 days △ ○ △ Comparative Example 8 ○ 10 days △ △ △ Comparative Example 9 × 48 hours ○ ○ ○ Comparative Example 10 ○ 10 days △ ○ ○ Comparative Example 11 ○ 15th △ ○ ○ Comparative Example 12 ○ 5 days ○ △ ○ Comparative Example 13 × 48 hours ○ ○ ○

As shown in Table 2, the pressure-sensitive adhesive compositions of Examples 2-1 to 2-11 containing a specific compound and a monomer containing a hydroxyl group according to the present invention had a shorter curing period and shorter storage stability than Comparative Examples 7 to 13 And excellent durability and reworkability were confirmed.

Claims (7)

An acrylic copolymer containing a compound represented by the following formula (1) or (2) and a monomer containing a hydroxyl group:
[Chemical Formula 1]

(2)

Wherein R ₁ is hydrogen or a methyl group, X is O or NH, and R ₂ is a straight or branched chain aliphatic hydrocarbon group having 1-12 carbon atoms, and the aliphatic hydrocarbon group includes N or O in the main chain And R ₃ and R ₄ are each independently selected from the group consisting of hydrogen, halogen, -OR ₅ , -N (R ₅ ) ₂ , -SR ₅ , -CN, -NO ₂ or An aliphatic hydrocarbon having 1 to 12 carbon atoms and R ₅ is an aliphatic hydrocarbon having 1 to 12 carbon atoms.
The compound according to claim 1, wherein the compound represented by Formula 1 or 2 is R ₁ hydrogen or a methyl group, X is oxygen, and R ₂ is a carbon number having an ether group, an ester group, or a urethane group in the main chain, And R &lt; ₃ &gt; and R &lt; ₄ &gt; are each independently hydrogen.
The acrylic copolymer according to claim 1, wherein the compound represented by Formula 1 or Formula 2 is at least one selected from the group consisting of the following Formulas 3 to 5:
(3)

[Chemical Formula 4]

[Chemical Formula 5]

The acrylic copolymer according to claim 1, wherein the acrylic copolymer contains a (meth) acrylate monomer having an alkyl group having 4 to 12 carbon atoms, a compound represented by the general formula (1) or (2), and a monomer containing a hydroxyl group.
[4] The acrylic copolymer according to claim 4, wherein the compound of Formula 1 or Formula 2 contains 0.1 to 10 parts by weight based on 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 4-12 carbon atoms.
A pressure-sensitive adhesive composition containing the acrylic copolymer according to any one of claims 1 to 5.
The pressure-sensitive adhesive composition according to claim 6, wherein the pressure-sensitive adhesive composition further comprises a crosslinking agent.