KR101991971B1 - Adhesive composition for acrylic film and polarizing plate containing threrof - Google Patents

Abstract

The present invention relates to a pressure-sensitive adhesive composition for an acrylic film and a polarizing plate containing the same, and more particularly, to a pressure-sensitive adhesive composition for an acrylic film containing 30 to 70 parts by weight of a methyl methacrylate monomer per 100 parts by weight of the total monomers, Containing acrylic copolymer B containing an acrylic copolymer A having an average molecular weight of 100,000 to 500,000 and a crosslinkable monomer and having a weight average molecular weight of 800,000 to 1,500,000, Sensitive adhesive property in an acrylic pressure-sensitive adhesive film and an acrylic pressure-sensitive adhesive film, and a polarizing plate containing the acrylic pressure-sensitive adhesive composition.

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition for an acrylic film, and a polarizing plate containing the pressure-

The present invention relates to a pressure-sensitive adhesive composition for an acrylic film excellent in durability and reworkability and a polarizing plate.

Adhesive is a material that adheres sufficiently to the adherend even under the application of pressure alone. It exhibits a viscoelastic behavior in which the cohesion is lower than that of the adhesive, the stress relaxation is faster, and the deformation easily occurs with respect to external force.

The raw materials used in the pressure-sensitive adhesive are mostly elastic materials such as natural rubber, synthetic rubber, acrylic, and silicone, so they have viscoelastic properties by mixing low molecular weight materials to impart viscous properties.

Recently, acrylic pressure-sensitive adhesives among the raw materials of pressure-sensitive adhesives have been rapidly used instead of rubber-based pressure-sensitive adhesives, and they can be used in a wide variety of forms such as solvent type, water-based emulsion type, hot melt type and 100% solid reaction type pressure-sensitive adhesive.

The acrylic pressure-sensitive adhesive is excellent in weather resistance, heat resistance, cold resistance and oil resistance as compared with the rubber-based pressure-sensitive adhesive, and can be made relatively easily for various purposes and applications. Therefore, it has been suggested that the adherence of acrylic adhesives has enabled the adhesive products to be used in a variety of different applications as at present.

On the other hand, in recent years, inexpensive polarizer materials are being developed in accordance with the tendency of LCD materials to be inexpensive. Particularly, interest in reducing the cost of polarizer protective films, which account for more than 50% of the cost of polarizer materials, is of interest. Accordingly, attempts have been made to use a polymethyl methacrylate resin having a high transmittance and low cost instead of conventional cellulose and cycloolefin polymer resins as a polarizer protective film.

In order to improve the bonding strength with the polarizer, the polarizer protective film is subjected to a step of performing a step of saponifying (alkali treating) the surface of the cellulose-based film and a step of corona-treating the surface of the cycloolefin polymer film to polarize (Korean Patent Laid-Open Publication No. 2009-114928).

However, it is difficult to polarize the surface of the polymethyl methacrylate-based film excellent in optical properties and price competitiveness by the corona treatment, and another pressure-sensitive adhesive for non-polarity is required. Although a variety of pressure-sensitive adhesives for non-polar use have been proposed (Japanese Patent Laid-Open Nos. 1-139655 and 4-154512), adhesion to polymethylmethacrylate films is insufficient and bonding strength is limited.

The present invention relates to a pressure-sensitive adhesive composition which can improve adhesion with an acrylic film (particularly a polymethylmethacrylate-based film), improve detachment defects under durability conditions (high temperature or high temperature and high humidity) Sensitive adhesive composition for an acrylic film (particularly a polymethyl methacrylate film).

In order to attain the above object, the present invention provides an acrylic copolymer composition comprising 30 to 70 parts by weight of a methyl methacrylate monomer based on 100 parts by weight of the total monomers, wherein the acrylic copolymer does not contain a crosslinkable monomer and has a weight average molecular weight of 100,000 to 500,000 A and an acrylic copolymer B containing a crosslinkable monomer and having a weight average molecular weight of 800,000 to 1,500,000.

Preferably, the acrylic copolymer A may have a weight average molecular weight of 200,000 to 40,000.

Preferably, the acrylic copolymer B may have a weight average molecular weight of 1, 000 to 120.

The acrylic copolymer (A) may be contained in an amount of 10 to 50 parts by weight based on 100 parts by weight of the acrylic copolymer (B).

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

Further, the present invention provides a polarizer wherein an acrylic polarizer protective film is bonded to at least one surface of a polarizer, and a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition is formed on the polarizer protective film.

The polarizer protective film may be a polymethyl methacrylate film.

The polarizing plate was cut into a size of 90 mm × 170 mm and attached to both sides of the glass substrate so that the optical absorption axes intersected with each other. The specimen was allowed to stand at a temperature of 80 ° C. for 1000 hours, have.

The polarizing plate was cut into a size of 90 mm × 170 mm and attached to both sides of the glass substrate so that the optical absorption axes intersected with each other. The specimen was allowed to stand at 60 ° C. and 90% RH for 1000 hours, May be less than five.

The pressure-sensitive adhesive composition of the present invention has an advantage of being able to simultaneously improve adhesion durability and reworkability under harsh conditions (high temperature or high temperature and high humidity) due to interaction with an interface at the interface of an acrylic film (particularly a polymethyl methacrylate film) .

Further, the pressure-sensitive adhesive composition of the present invention has an advantage that the deterioration of coating uniformity due to the use of an acrylic copolymer containing a methyl methacrylate monomer can be advantageously suppressed.

The present invention relates to a pressure-sensitive adhesive composition and a polarizer that are excellent in durability and reworkability.

Hereinafter, the present invention will be described in detail.

In order to achieve the above objects, the present invention provides a pressure-sensitive adhesive composition for an acrylic film, which comprises 30 to 70 parts by weight of methyl methacrylate monomer per 100 parts by weight of total monomers, does not contain a crosslinking monomer, An acrylic copolymer A having a molecular weight of 100,000 to 500,000 and an acrylic copolymer B containing a crosslinkable monomer and having a weight average molecular weight of 700,000 to 1,500,000.

The pressure-sensitive adhesive composition of the present invention is a mixture of an acrylic copolymer which is crosslinkable and has a high molecular weight and an acrylic copolymer which is incompatible and has a low molecular weight and contains methyl methacrylate monomer. At this time, the acrylic copolymer having a low molecular weight moves to the base material side of the acrylic film (in particular, the PMMA film) and improves adhesion with the film due to strong interaction with the film surface, The workability is improved at the same time.

In addition, the pressure-sensitive adhesive composition of the present invention may be degraded in uniformity due to the methyl methacrylate-containing acrylic copolymer used for improving the interfacial adhesion with the acrylic film. Thus, by controlling the content of methyl methacrylate and the molecular weight of the copolymer, the coating uniformity was reduced.

The acrylic copolymers A and B each contain a (meth) acrylate monomer having an alkyl group of 1-12 carbon atoms as a main monomer, and the acrylic copolymer A is a (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms and Methyl methacrylate monomer as an essential monomer component.

Here, (meth) acrylate means acrylate and methacrylate, and the content of each component is based on the solid content.

Examples of the (meth) acrylate monomer having an alkyl group of 1 to 12 carbon atoms include (meth) acrylates derived from an aliphatic alcohol having 1 to 12 carbon atoms, such as methyl acrylate, ethyl acrylate, propyl acrylate, n (Meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl Nonyl (meth) acrylate, decyl (meth) acrylate, and lauryl (meth) acrylate. These may be used alone or in admixture of two or more. Of these, n-butyl acrylate, 2-ethylhexyl acrylate or a mixture thereof is preferable.

The acrylic copolymer A may contain 30 to 70 parts by weight, preferably 40 to 60 parts by weight, of methyl methacrylate monomer based on 100 parts by weight of the total monomers. If the content is less than 30 parts by weight, the adhesion improving effect with the acrylic film may be insufficient. If the content is more than 70 parts by weight, the compatibility with the acrylic copolymer B may be insufficient and phase separation may occur.

The acrylic copolymer B contains a crosslinkable monomer having a crosslinkable functional group.

The crosslinkable monomer has a function of imparting cohesive strength or cohesive strength by chemical bonding with the following crosslinking agent, and examples thereof include monomers having a hydroxyl group, monomers having a carboxyl group, monomers having an amide group, and monomers having a tertiary amine group have. These may be used alone or in combination of two or more.

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.

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.

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.

The crosslinkable monomer of the acrylic copolymer B is preferably contained in an amount of 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, per 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms good. 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 crosslinking monomers other than the above-mentioned monomers may be further added in an amount not lowering the adhesive force, for example, 40 parts by weight or less based on 100 parts by weight of the total monomers used for producing 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.

It is preferable that the acrylic copolymer A has a weight average molecular weight (in terms of polystyrene, Mw) of 100,000 to 500,000, preferably 200,000 to 400,000 as measured by Gel Permeation Chromatography (GPC). If the weight average molecular weight is less than 100,000, the acrylic copolymer A containing methyl methacrylate which moves to the surface during mixing tends to cause problems in adhesion durability such as bubbling due to insufficient cohesion between the copolymers, The mobility to the surface is insufficient and the effect of improving adhesion with the protective film (PMMA) may be insufficient.

The acrylic copolymer B preferably has a weight average molecular weight of 800,000 to 1,500,000, preferably 1,000,000 to 1,200,000. If the weight average molecular weight is less than 800,000, the cohesive force is insufficient and there is a fear of generation of bubbles. If the weight average molecular weight is more than 1,500,000, the increase in viscosity may cause unevenness during coating.

The acrylic copolymer (A) is preferably contained in an amount of 10 to 50 parts by weight, preferably 20 to 45 parts by weight, based on 100 parts by weight of the acrylic copolymer (B). If the content is less than 10 parts by weight, the adhesion enhancing effect with the acrylic film may be insufficient. If the content is more than 50 parts by weight, a relatively large amount of non-cross-linkable copolymer may exist and bubbles may be generated due to lack of cohesive force.

The pressure-sensitive adhesive composition of the present invention may further contain a crosslinking agent.

The crosslinking agent can improve the adhesion and durability, and can maintain the reliability at a high temperature and the shape of the pressure-sensitive adhesive.

The cross-linking agent may be an isocyanate-based, epoxy-based, melamine-based, peroxide-based, metal chelating-based, oxazoline-based, or the like. Preferred is a double isocyanate-based or epoxy-based.

Examples of the isocyanate-based isocyanate include isocyanate-based compounds such as tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate, Diisocyanate compounds such as isocyanate; 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.

The epoxy system may be an ethylene glycol diglycidyl ether, a diethylene glycol diglycidyl ether, a polyethylene glycol diglycidyl ether, a propylene glycol diglycidyl ether, a tripropylene glycol diglycidyl ether, a polypropylene glycol di Hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, diethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, Glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcinol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, trimethylol propane triglycidyl ether, pentaerythritol poly Glycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanurate N, N, N ', N'-tetraglycidyl-m-hexyldicyclohexyl) isocyanurate, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, Xylylenediamine, and the like.

Examples of the melamine type include hexamethylol melamine, hexamethoxymethyl melamine, and hexabutoxymethyl melamine.

Such a crosslinking agent may be contained in an amount of 0.1 to 15 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the acrylic copolymer. If the content is less than 0.1 part by weight, the cohesive strength may be decreased due to insufficient crosslinking, which may deteriorate the durability of the adhesive durability and the cutability. If the content is more than 15 parts by weight, the residual stress due to the excessive crosslinking reaction may be deteriorated.

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 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, a dye, a pigment, and the like in order to control adhesion, cohesion, viscosity, , Defoaming agents, fillers, light stabilizers, and the like.

Further, the present invention is characterized in that a polarizer protective film is bonded to at least one surface of a polarizer, and a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition is formed on the polarizer protective film. At this time, the pressure-sensitive adhesive layer is formed on the opposite side of the bonding surface of the polarizer protective film.

The acrylic polarizer protective film may preferably be a polymethyl methacrylate film.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Manufacturing example  : Acrylic copolymer preparation

Manufacturing example  1: Acrylic copolymer A

Manufacturing example  1-1

A monomer mixture composed of 50 parts by weight of n-butyl acrylate (BA) and 50 parts by weight of methyl methacrylate (MA) was introduced into a 1 L reactor equipped with a cooling device for regulating the temperature of the nitrogen gas and facilitating the temperature control. Was added 200 parts by weight of ethyl acetate (EAc). Nitrogen gas was then purged for 1 hour to remove oxygen and then maintained at 80 ° C. After the mixture was homogeneously mixed, 0.07 part by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to prepare an acrylic copolymer (weight average molecular weight: about 350,000).

Manufacturing example  1-2 to 1-7 and comparison Manufacturing example  1-1 to 1-2

The acrylic copolymer was prepared in the same manner as in Preparation Example 1-1 except that the components were mixed and reacted as shown in Table 1 below.

division
(Parts by weight) BA MMA Solvent (EAc) Weight average molecular weight
(Mw, only) Production Example 1-1 50 50 200 35 Production Example 1-2 70 30 200 37 Production Example 1-3 60 40 200 32 Production Example 1-4 40 60 200 33 Production Example 1-5 30 70 200 38 Production Example 1-6 50 50 300 15 Preparation Example 1-7 50 50 150 47 Comparative Production Example 1-1 10 90 200 38 Comparative Production Example 1-2 90 10 200 33 BA: n-butyl acrylate
MMA: methyl methacrylate

Manufacturing example  2: Acrylic copolymer B

97 parts by weight of n-butyl acrylate (BA), 1 part by weight of acrylic acid (AA), 4 parts by weight of 4-hydroxybutyl acrylate (4-HBA ), And then 100 parts by weight of ethyl acetate (EAc) was added as a solvent. Nitrogen gas was then purged for 1 hour to remove oxygen and then maintained at 80 ° C. After the mixture was homogeneously mixed, 0.07 part by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to prepare an acrylic copolymer (weight average molecular weight: about 1,000,000).

Manufacturing example  2-2 to 2-6 and comparison Manufacturing example  2-1 to 2-2

The acrylic copolymer was prepared in the same manner as in Preparation Example 2-1 except that the components were mixed and reacted as shown in Table 2 below.

division
(Parts by weight) BA AA 4-HBA 2-HEA Solvent (EAc) Weight average molecular weight
(Mw, only) Production Example 2-1 97 One 2 - 100 100 Production example 2-2 93 5 2 - 100 100 Production Example 2-3 97 One - 2 100 100 Production example 2-4 97 One 2 - 80 145 Production example 2-5 97 One 2 - 130 85 Comparative Production Example 2-1 97 One 2 - 130 70 Comparative Production Example 2-2 97 One 2 - 70 170 BA: n-butyl acrylate
MA: methacrylate
2-HEA: 2-hydroxyethyl acrylate
4-HBA: 4-hydroxybutyl acrylate

Example  1-16 and Comparative Example  1-6

1) Pressure-sensitive adhesive composition

The acrylic copolymer, the crosslinking agent and the silane coupling agent of Preparation Example 1 and Preparation Example 2 were mixed in the composition shown in Table 3, and then diluted to a concentration of 20% by weight in consideration of coating property to prepare a pressure-sensitive adhesive composition.

division
(Parts by weight) Acrylic copolymer Cross-linking agent Silane
Coupling agent Production Example 1 Production Example 2 compare
Production Example 1 compare
Production Example 2 A-1 A-2 A-3 A-4 Example 1 1-1 (30) 2-1 (70) - - 0.5 - - - 0.5 Example 2 1-2 (30) 2-1 (70) - - 0.5 - - - 0.5 Example 3 1-3 (30) 2-1 (70) - - 0.5 - - - 0.5 Example 4 1-4 (30) 2-1 (70) - - 0.5 - - - 0.5 Example 5 1-5 (30) 2-1 (70) - - 0.5 - - - 0.5 Example 6 1-6 (30) 2-1 (70) - - 0.5 - - - 0.5 Example 7 1-7 (30) 2-1 (70) - - 0.5 - - - 0.5 Example 8 1-1 (30) 2-2 (70) - - 0.5 - - - 0.5 Example 9 1-1 (30) 2-3 (70) - - 0.5 - - - 0.5 Example 10 1-1 (30) 2-4 (70) - - 0.5 - - - 0.5 Example 11 1-1 (30) 2-5 (70) - - 0.5 - - - 0.5 Example 12 1-1 (15) 2-1 (85) - - 0.5 - - - 0.5 Example 13 1-1 (45) 2-1 (55) - - 0.5 - - - 0.5 Example 14 1-1 (30) 2-6 (70) - - - 0.5 - - 0.5 Example 15 1-1 (30) 2-6 (70) - - - - 0.5 - 0.5 Example 16 1-1 (30) 2-6 (70) - - - - - 0.5 0.5 Comparative Example 1 1-1 (100) - - - 0.5 - - - 0.5 Comparative Example 2 - 2-1 (100) - - 0.5 - - - 0.5 Comparative Example 3 1-1 (30) - - 2-1 (70) 0.5 - - - 0.5 Comparative Example 4 1-1 (30) - - 2-2 (70) 0.5 - - - 0.5 Comparative Example 5 - 2-1 (70) 1-1 (30) - 0.5 - - - 0.5 Comparative Example 6 - 2-1 (70) 1-2 (30) - 0.5 - - - 0.5 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: glycidoxypropyltrimethoxysilane (Shin-Etsu, KBM403)
The crosslinking agent and the silane coupling agent have a weight ratio of 100 parts by weight to the total content of the acrylic copolymer

2) Polarizer with adhesive

1) was cured on a releasing film coated with a silicone release agent, and then coated to a thickness of 25 占 퐉 and dried at 100 占 폚 for 1 minute, 5 minutes and 10 minutes to form an adhesive layer.

A polarizing plate having a polymethyl methacrylate protective film bonded to both sides of the polarizer was laminated on the pressure-sensitive adhesive layer to prepare a polarizing plate with a pressure-sensitive adhesive. At this time, the protective film surface and the adhesive layer were laminated so as to be in contact with each other. The prepared polarizing plate was stored for a curing period under the conditions of 23 캜 and 60% RH.

Test Example

The physical properties of 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 4 below.

1. 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 < 2 >, 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 &

××: Bubbles or peeling in the front

2. Re-workability

The polarizing plate was cut to a size of 25 mm in width and 100 mm in length, and the release film was peeled off. The release film was laminated on Corning # 1737 glass at a pressure of 0.25 MPa and autoclaved for 20 minutes under conditions of 5 atm and 50 캜 Evaluation samples were prepared. After putting it in an oven at 50 ° C for 5 hours, it was taken out at room temperature for 120 hours and then peeled at a rate of 1.3 cm / s. In addition, it was placed in an oven at 60 DEG C and 90RH% in a humid condition, taken out after 4 hours, left at room temperature for 120 hours, and peeled at a rate of 1.3 cm / s.

<Evaluation Criteria>

- No adhesive residue on the glass substrate in both conditions and cleanly peeled off without tearing of the polarizer: ○

- Adhesive remains on the panel under either condition, or the polarizer tears during peeling: x

3. Coating uniformity

The prepared polarizer with a pressure-sensitive adhesive was cut into a size of 90 mm x 170 mm, the release film was peeled off, adhered to one surface of a glass substrate (110 mm x 190 mm x 0.7 mm) Uniformity was confirmed.

<Evaluation Criteria>

- Non-uniformity of adhesive was not observed with reflected light: ○

- Non-uniformity of adhesive was observed with reflected light, but observed faintly:

- An orange peel-like unevenness caused by unevenness of the adhesive when observed with reflected light was observed: x

division durability Re-workability Coating uniformity Heat resistance Wet heat Example 1 Ⓞ Ⓞ ○ ○ Example 2 ○ Ⓞ ○ ○ Example 3 Ⓞ Ⓞ ○ ○ Example 4 Ⓞ Ⓞ ○ ○ Example 5 Ⓞ Ⓞ ○ △ Example 6 ○ ○ ○ ○ Example 7 ○ ○ ○ △ Example 8 Ⓞ Ⓞ ○ ○ Example 9 Ⓞ Ⓞ ○ ○ Example 10 Ⓞ Ⓞ ○ △ Example 11 ○ Ⓞ ○ ○ Example 12 ○ Ⓞ ○ ○ Example 13 ○ Ⓞ ○ △ Example 14 ○ Ⓞ ○ ○ Example 15 ○ Ⓞ ○ ○ Example 16 ○ Ⓞ ○ ○ Comparative Example 1 Xx Xx ○ ○ Comparative Example 2 × ○ × ○ Comparative Example 3 × ○ ○ ○ Comparative Example 4 Ⓞ Ⓞ ○ × Comparative Example 5 ○ Ⓞ ○ × Comparative Example 6 × Ⓞ × ○

As shown in Table 4, the pressure-sensitive adhesive compositions of Examples 1 to 16 according to the present invention exhibited excellent adhesion durability such as heat resistance and anti-wet heat and reworkability at the time of bonding with an acrylic film as compared with Comparative Examples 1 to 6, It was confirmed that it exhibited one coatability.

Claims (9)

An acrylic copolymer A containing 30 to 70 parts by weight of a methyl methacrylate monomer relative to 100 parts by weight of total monomers and containing no crosslinkable monomer and having a weight average molecular weight of 100,000 to 500,000,
An acrylic copolymer B containing a crosslinkable monomer and having a weight average molecular weight of 800,000 to 1,500,000;
Wherein the acrylic copolymer (A) is contained in an amount of 10 to 50 parts by weight based on 100 parts by weight of the acrylic copolymer (B).
The pressure-sensitive adhesive composition for an acrylic film according to claim 1, wherein the acrylic copolymer (A) has a weight average molecular weight of 200,000 to 400,000.
The pressure-sensitive adhesive composition for an acrylic film according to claim 1, wherein the acrylic copolymer (B) has a weight average molecular weight of 1 million to 1,200,000.
delete The pressure-sensitive adhesive composition for an acrylic film according to claim 1, wherein the pressure-sensitive adhesive composition further contains a crosslinking agent.
A polarizer protective film is bonded to at least one surface of the polarizer, and a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition of any one of claims 1 to 3 and 5 is formed on the polarizer protective film.
The polarizer of claim 6, wherein the polarizer protective film is a polymethyl methacrylate film.
The method of claim 6, wherein the polarizing plate is cut into a size of 90 mm × 170 mm, and the specimen attached to both sides of the glass substrate so that the optical absorption axes cross each other is left at a temperature of 80 ° C. for 1000 hours, Lt; RTI ID = 0.0 &gt; 5. &Lt; / RTI &gt;
7. The method of claim 6, wherein the polarizing plate is cut into a size of 90 mm x 170 mm, and the specimen adhered to both sides of the glass substrate so that the optical absorption axes cross each other is left for 1000 hours at a temperature of 60 DEG C and a relative humidity of 90% Wherein the occurrence of bubbles or peeling is less than five.