KR20190059138A - Adhesive composition for polarizing plate, polarizing plate and optical display apparatus - Google Patents

Abstract

The present invention relates to an adhesive composition for a polarizing plate having excellent adhesion to a TAC film, a PET film and a COP film, to a polarizing plate, and to an optical display device. The adhesive composition for a polarizing plate comprises: an epoxy compound; a (meth)acrylate compound; and a photo-initiator, wherein the epoxy compound includes an alicyclic epoxy compound and an aromatic epoxy compound. In addition, the aromatic epoxy compound comprises 10 to 30 parts by weight of polyglycidyl ether of an aromatic compound in 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound.

Description

TECHNICAL FIELD [0001] The present invention relates to an adhesive composition for a polarizing plate, a polarizing plate, and an optical display device.

The present invention relates to an adhesive composition for a polarizing plate, a polarizing plate and an optical display device. More specifically, the present invention relates to a photo-curable adhesive composition for a polarizing plate, a polarizing plate and an optical display device.

The liquid crystal display device includes a liquid crystal panel and a polarizing plate formed on both sides of the liquid crystal panel. The polarizing plate includes an optical film formed on both sides of the polarizer and the polarizer, respectively. In recent years, an optical film is formed on one surface of a polarizer and a coating layer is formed on the other surface of the polarizer to thin the polarizer.

Since a polarizer adhesive provides adhesion between a PVA film and a cellulose-based optical film, a hydrophilic and water-soluble PVA adhesive is widely used. In the polarizing plate using the water-based adhesive, the dimension of the polarizing plate is changed by the heat of the backlight, the distortion due to the dimensional change is localized in a part of the screen, and as a result, There is a problem in that so-called light leakage (dirt), in which light partially leaks, becomes remarkable. Therefore, it has been proposed to use a cationic polymerizable ultraviolet curing type adhesive instead of an aqueous adhesive (see, for example, Japanese Laid-Open Patent Publication No. 2008-233874).

In the cationic polymerizable ultraviolet curing type adhesive, a dark reaction (post polymerization) takes place after irradiation with ultraviolet rays, so that when the cured product is formed into a wound roll shape, there is a problem that it is easily dried during storage. In addition, the cationic polymerizable ultraviolet curable adhesive is susceptible to the influence of humidity at the time of curing, and there is a problem that deviation in the cured state easily occurs. Therefore, it is necessary to strictly control the moisture content of the PVA-based polarizer as well as the environmental humidity in order to exhibit a uniform curing state.

Radical polymerizing ultraviolet curable adhesives are excellent in that such problems are relatively small. When a radical polymerizing ultraviolet curable adhesive is used, the polarizing performance tends to deteriorate when exposed for a long time under a humid environment, and there is a problem that a light leakage phenomenon of a polarizer colored with iodine or a dye tends to occur at the cut end. In addition, in a harsher condition (for example, immersion in hot water of 60) than in the case of a humid environment, the phenomenon of light leakage of the polarizer occurs remarkably. That is, there is a demand for a polarizing plate having more excellent heat and humidity resistance than conventional polarizing plates today, in which the use environment of polarizing plates is more severe. Further, an adhesive composition for using a (meth) acrylic radical polymerizing compound and a cationic polymerizing compound in combination to easily adhere the polarizing plate polyvinyl alcohol film and the plastic film with sufficient strength has also been proposed (Japanese Patent Application Laid-Open No. 2008-260879 Reference).

It is an object of the present invention to provide an adhesive composition for a polarizing plate which is excellent in adhesion to both a TAC film, a PET film and a COP film.

Another object of the present invention is to provide an adhesive composition for a polarizing plate having an excellent adhesive force to a COP film produced by a solution casting method.

It is still another object of the present invention to provide an adhesive composition for a polarizing plate capable of blocking or minimizing cracking of a polarizer upon thermal shock.

It is still another object of the present invention to provide an adhesive composition for a polarizing plate, which has excellent adhesion to a polarizer, a PET film, a COP film, and a TAC film even after being left at high temperature and high humidity.

The adhesive composition for a polarizing plate of the present invention comprises an epoxy compound, a (meth) acrylate compound and a photoinitiator, wherein the epoxy compound includes an alicyclic epoxy compound and an aromatic epoxy compound, and the aromatic epoxy compound The polyglycidyl ether of the aromatic compound may be contained in an amount of 10 to 30 parts by weight per 100 parts by weight of the sum of the epoxy compound and the (meth) acrylate compound.

The polarizing plate of the present invention may include an adhesive layer formed of the adhesive composition for a polarizing plate of the present invention.

The optical display device of the present invention may include the polarizing plate of the present invention.

The present invention provides an adhesive composition for a polarizing plate having excellent adhesion to both TAC film, PET film and COP film.

The present invention provides an adhesive composition for a polarizing plate having an excellent adhesion to a COP film produced by a solution casting method.

The present invention provides an adhesive composition for a polarizing plate capable of blocking or minimizing cracking of a polarizer upon thermal shock.

The present invention provides an adhesive composition for a polarizing plate, which has excellent adhesion to a polarizer, a PET film, a COP film, and a TAC film even after being left at high temperature and high humidity.

Hereinafter, embodiments of the present application will be described in more detail with reference to the accompanying embodiments. However, the techniques disclosed in this application are not limited to the embodiments described herein but may be embodied in other forms. It should be understood, however, that the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

As used herein, " (meth) acrylic " means acrylic and / or methacrylic.

As used herein, the term " optical film " includes a protective film laminated on a polarizer by an adhesive layer, and may include a non-stretched film having no retardation or a stretched film having a predetermined range of retardation.

Hereinafter, an adhesive composition for a polarizing plate according to an embodiment of the present invention will be described.

The adhesive composition for a polarizing plate according to the present embodiment comprises an epoxy compound, a (meth) acrylate compound and a photoinitiator, wherein the epoxy compound includes an aromatic epoxy compound and an alicyclic epoxy compound, Based compound may include 10 to 30 parts by weight of the polyglycidyl ether of the aromatic compound in 100 parts by weight of the sum of the epoxy compound and the (meth) acrylate compound. The adhesive composition of the present invention comprises a cellulose-based film comprising a TAC film, a cycloolefin polymer film and a PET film by including a polyglycidyl ether of an aromatic compound in the above content range and including a (meth) acrylate-based compound The adhesive strength and water resistance to all of the polyester films of the present invention are excellent, and the crack length of the polarizer is lowered under thermal shock, whereby the reliability can be improved. The polarizing plate including the adhesive layer formed of the adhesive composition for a polarizing plate of the present invention was subjected to 100 cycles of 1 cycle in which the polarizer was allowed to stand at -40 占 폚 for 30 minutes, elevated from -40 占 폚 to 85 占 폚 and left at 85 占 폚 for 30 minutes, The maximum value of the machine direction (MD) crack length of the polarizer may be 3 mm or less. Within the above range, the degree of polarization and the light transmittance may not be lowered even by thermal shock.

The protective film formed of an optically transparent resin can be produced by a solution casting method, a melt extrusion method, a calendering method, a compression molding method, or the like. Particularly, the solution casting method is manufactured by dissolving an optically transparent resin in a predetermined solvent and then casting it by using a drum casting machine, a band casting machine, a spin coater or the like. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene and xylene; Aliphatic hydrocarbons such as cyclohexane and decalin; Esters such as ethyl acetate and butyl acetate; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Ethers; Halogenated hydrocarbons; Dimethylformamide, and the like. The protective film surfaces produced by the respective methods are different from each other. Conventional adhesive compositions have low adhesion to cycloolefin films prepared by the solution casting method. The adhesive composition of the present invention can be excellent in adhesion and water resistance to the cycloolefin polymer film produced by the solution casting method. Preferably, the polyglycidyl ether of the aromatic compound may be contained in an amount of 10 to 25 parts by weight.

The aromatic epoxy compound may include a polyglycidyl ether of an aromatic compound. For example, the polyglycidyl ether of an aromatic compound may comprise a polyglycidyl ether formed from an aromatic compound having at least two hydroxyl groups. Specifically, the polyglycidyl ether of the aromatic compound is a monohydric phenol having at least one aromatic ring such as phenol, cresol, and butylphenol, or a polyglycidyl ether compound thereof, such as bisphenol A, Bisphenol F or glycidyl ether compounds or epoxy novolac resins in which an alkylene oxide is added thereto; Polyglycidyl ether compounds of aromatic compounds having two or more phenolic hydroxyl groups such as resorcinol, hydroquinone, or catechol; Polyglycidyl ether compounds of aromatic compounds having two or more alcoholic hydroxyl groups such as benzene dimethanol, benzene diethanol and benzene dibutanol; Glycidyl esters which are polybasic acid aromatic compounds having two or more carboxylic acids such as phthalic acid, terephthalic acid and trimellitic acid; Glycidyl esters of benzoic acids such as benzoic acid, toluic acid, and naphthoic acid; Styrene oxide; And epoxides of divinyl benzene.

Preferably, the polyglycidyl ether of the aromatic compound may comprise a diglycidyl ether of an aromatic compound. The diglycidyl ether of the aromatic compound may include a diglycidyl ether formed from an aromatic compound having two or more phenolic hydroxyl groups. For example, a diglycidyl etherified or polyglycidyl etherified product of an aromatic compound having two or more phenolic hydroxyl groups such as resorcinol, hydroquinone, or catechol. Specifically, the polyglycidyl ether of the aromatic compound includes at least one of catechol diglycidyl ether including resorcinol diglycidyl ether, hydroquinone diglycidyl ether, and pyrocatechol diglycidyl ether. can do.

The polyglycidyl ether of the aromatic compound may be contained in an amount of 10 to 50 parts by weight, preferably 10 to 40 parts by weight, more preferably 10 to 35 parts by weight, based on 100 parts by weight of the epoxy compound. Within this range, cracking in thermal shock resistance and excellent adhesion to COP films can be obtained.

The aromatic epoxy compound may further include a monoglycidyl ether of an aromatic compound. By further including a monoglycidyl ether of an aromatic compound, the viscosity of the adhesive composition is lowered, and the effect of improving the coating property and coating property of the adhesive composition may be further increased. The monoglycidyl ether of the aromatic compound may comprise a glycidyl ether formed from an aromatic compound having one hydroxyl group. For example, the monoglycidyl ether of an aromatic compound may include one or more of phenyl glycidyl ether, cresyl glycidyl ether, nonylphenyl glycidyl ether.

The monoglycidyl ether of the aromatic compound may be used in an amount of 0 to 20 parts by weight, 1 to 20 parts by weight, preferably 2 parts by weight (based on 100 parts by weight of the total of the epoxy compound and the (meth) To 15 parts by weight, more preferably 5 parts by weight to 15 parts by weight. Within the above range, there may be an effect of lowering the viscosity of the whole adhesive, controlling the reaction, and improving adhesion to COP films.

The monoglycidyl ether of the aromatic compound may be contained in an amount of 0 to 30 parts by weight, preferably 1 to 30 parts by weight, based on 100 parts by weight of the epoxy compound. Within this range, cracking in thermal shock resistance and excellent adhesion to COP films can be obtained.

The alicyclic epoxy compound can be polymerized by cations initiated by light energy. The alicyclic epoxy group has a functional group in which the C3 to C20 alicyclic group is epoxidized, a C2 to C20 alicyclic group having a functional group in which the C3 to C20 alicyclic group is epoxidized, or a functional group in which the C3 to C20 alicyclic group is epoxidized Means a C1 to C10 alkyl group. Specifically, the alicyclic epoxy group means at least one of an epoxycyclohexyl group, an epoxycyclopentyl group and a glycidyl group.

Bifunctional alicyclic epoxy compounds among the alicyclic epoxy compounds may be used. The bifunctional alicyclic epoxy compound is a compound having two alicyclic epoxy groups. The bifunctional alicyclic epoxy compound has a high glass transition temperature of the homopolymer to support the laminated structure of the polarizer, the adhesive layer and the optical film to enhance the durability, and the polarizer and the optical film Can be increased. The bifunctional alicyclic epoxy compound may have a glass transition temperature of the homopolymer of 150 占 폚 or higher, for example, 150 占 폚 to 400 占 폚. In the above range, it is possible to prevent cracking of the polarizer upon thermal shock.

In one embodiment, the bifunctional alicyclic epoxy compound is epoxycyclohexylmethyl epoxycyclohexanecarboxylate-based, epoxycyclohexanecarboxylate-based alkane diol, epoxycyclohexylmethylester-based dicarboxylic acid ester, epoxide of polyethylene glycol Epoxycyclohexylmethyl ether, cyclohexyl methyl ether, alkane diol, epoxycyclohexyl methyl ether, diepoxy trispyrene, diepoxy monospiro, vinylcyclohexene diepoxide, epoxycyclopentene ether, and diepoxytricyclodecane compounds .

The bifunctional alicyclic epoxy-based compound is 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3', 4'- (3,4-epoxy-6-methylcyclohexyl) adipate, 3,4-Epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate modified epsilon-caprolactone can do. For example, the bifunctional alicyclic epoxy compound may be CELLOXIDE 2021P (DIACEL), CELLOXIDE 8000 (DIACEL) or the like, but is not limited thereto.

The bifunctional alicyclic epoxy compound may be contained in an amount of 20 to 80 parts by weight, preferably 30 to 70 parts by weight, based on 100 parts by weight of the total of the epoxy compound and the (meth) acrylate compound. In the above range, there is no problem that the modulus of the adhesive layer excessively increases and the adhesive layer becomes brittle, and there is no problem in the cutting property.

The bifunctional alicyclic epoxy compound may be contained in an amount of 50 to 90 parts by weight, preferably 50 to 89 parts by weight, based on 100 parts by weight of the epoxy compound. Within this range, cracking in thermal shock resistance and excellent adhesion to COP films can be obtained.

The alicyclic epoxy compound may further include a monofunctional alicyclic epoxy compound or a trifunctional or higher alicyclic epoxy compound. The monofunctional alicyclic epoxy compound, and the trifunctional or more alicyclic epoxy compound may be used in common types known to those skilled in the art.

The epoxy compound may further include at least one of an aliphatic epoxy compound and a hydrogenated aromatic epoxy compound. The aliphatic epoxy compound and the hydrogenated aromatic epoxy compound may each be a conventional one known to those skilled in the art.

The epoxy compound may be contained in an amount of 40 to 95 parts by weight, preferably 60 to 90 parts by weight, based on 100 parts by weight of the sum of the epoxy compound and the (meth) acrylate compound. Within the above range, the Tg may be increased, which leads to an excellent crack resistance in the thermal shock and a synergistic effect of the adhesion of the COP film.

The (meth) acrylate-based compound may include a monofunctional (meth) acrylate-based compound having at least one hydroxyl group.

The monofunctional (meth) acrylate compound having at least one hydroxyl group does not inhibit the reaction by moisture and can stably react to light energy without being inhibited by the curing reaction caused by moisture of the adjacent polarizer. Also, adhesion between the polarizer and the protective film can be improved by the chain-bonding between the polarizer and the protective film and the cationic-activated epoxy compound during the curing process. The monofunctional (meth) acrylate compound having at least one hydroxyl group may have a glass transition temperature (Tg) of 0 占 폚 or less of the homopolymer. (Meth) acrylate-based compound having a glass transition temperature of 0 ° C or lower, the homopolymer can prevent the cracking of the polarizer due to thermal shock even when the homopolymer contains an epoxy compound having a high glass transition temperature in an excessive amount, It is possible to prevent the brittle phenomenon of the adhesive layer. Preferably, the monofunctional (meth) acrylate-based compound may have a glass transition temperature of the homopolymer of -80 ° C to -10 ° C.

For example, the monofunctional (meth) acrylate compound having at least one hydroxyl group may be at least one compound selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) (Meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and the like.

The monofunctional (meth) acrylate compound having at least one hydroxyl group is added in an amount of 5 to 60 parts by weight, preferably 10 to 40 parts by weight, per 100 parts by weight of the total of the epoxy compound and the (meth) acrylate compound By weight. In the above range, the adhesion between the polarizer and the protective film is improved, and when the alicyclic epoxy is used, it is possible to prevent the excessive increase of Tg, thereby preventing the brittleness characteristic.

The (meth) acrylate-based compound may further include a (meth) acrylate-based compound having a functional group that is hydrophobic at the ester portion of the (meth) acrylate-based compound. The hydrophobic functional group can prevent the adhesiveness of the adhesive layer to the optical film or the polarizer from being deteriorated by the external moisture when the optical film and the polarizer are bonded with the adhesive for the polarizing plate. Further, in the adhesive composition for a polarizing plate of the present invention, the hydrophobic functional group can prevent the scattering of the adhesive force between the polarizer and the adhesive layer or the adhesive layer between the optical film and the adhesive layer by the external moisture. Preferably, the hydrophobic functional group may be a linear or branched alkyl group having 10 to 20 carbon atoms, for example, a lauryl group, an isodecyl group, and the like.

(Meth) acrylate compound may be contained in an amount of 5 to 60 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the total of the epoxy compound and the (meth) acrylate compound. In the above range, the adhesion between the polarizer and the protective film is improved, and when the alicyclic epoxy is used, it is possible to prevent the excessive increase of Tg, thereby preventing the brittleness characteristic.

The photoinitiator may include at least one of a photoacid generator and a photo radical initiator.

As the photoacid generator, an onium salt including a cation and an anion may be used. Specifically, the cation includes triarylsulfonium such as triphenylsulfonium, diphenyl-4- (phenylthio) phenylsulfonium and diphenyl-4-thiophenoxyphenylsulfonium, bis [4- Phenyl] sulfide and the like. Specifically, the anion is phosphate (PF ₆ ^-) hexafluoropropane, borates (BF ₄ ^-) tetrafluoroborate, antimonate hexafluorophosphate (SbF ₆ ^-), are Senate hexafluorophosphate (AsF ₆ ^-), hexamethylene And chlorantimonate (SbCl ₆ ^- ).

The photoacid generator may be added in an amount of 0.1 to 10 parts by weight, for example, 1 to 6 parts by weight based on 100 parts by weight of the total amount of the epoxy compound and the (meth) acrylate compound. Within the above range, the epoxy compound can be sufficiently cured, the adhesive strength is not lowered, and the remaining amount of the photoacid generator remains, thereby lowering the transparency of the adhesive layer or preventing bleed-out of the photoacid generator.

When used together with the photoacid generator, the photo radical initiator can lower the color coordinate bs of the adhesive layer and cure the (meth) acrylate compound. Photoinitiators may be those commonly known to those skilled in the art. Specifically, at least one of phosphorus, triazine, acetophenone, benzophenone, benzoin, and oxime can be used as the photoinitiator. The polarizing plate including the adhesive layer formed of the adhesive composition for a polarizing plate of the present invention may have a color coordinate bs value of 3 or less, for example, 0 to 3. In the above-described range, yellow is not visually observed when the polarizing plate is used in the optical display device, and the visual feeling is excellent.

The photo-radical initiator may be included in an amount of 0.1 part by weight to 10 parts by weight, for example, 1 part by weight to 7 parts by weight, based on 100 parts by weight of the total amount of the epoxy compound and the (meth) acrylate compound. Within this range, the (meth) acrylate-based compound can be sufficiently cured and the remaining amount of the photo-radical initiator remains, which can lower the transparency of the adhesive layer or prevent bleed-out of the photo-radical initiator.

The adhesive composition for a polarizing plate may include a solvent, but may be a solventless adhesive composition containing no solvent. By using a solvent-free adhesive composition, the influence on the optical film can be minimized.

The adhesive composition for a polarizing plate may further contain additives such as an antioxidant, an adhesion promoter, an antistatic agent, a leveling agent, a defoaming agent, and a UV absorber.

The adhesive composition for a polarizing plate may have a viscosity at 25 DEG C of from 20 cps to 100 cps. Within the above range, application of the adhesive composition may be easy.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described.

The polarizing plate includes a polarizer and an optical film formed on at least one side of the polarizer, and the optical film can be adhered to the polarizer by an adhesive layer formed by the adhesive composition for a polarizing plate of the present invention.

The polarizer can polarize the external light incident on the polarizing plate. The polarizer may include a polarizer made of a polyvinyl alcohol-based resin film. In one embodiment, the polarizer may be a polyvinyl alcohol-based polariser on which at least one of iodine and dichroic dye is adsorbed to a polyvinyl alcohol-based resin film. In another embodiment, the polarizer may be a polyene polarizer prepared by dewatering a polyvinyl alcohol-based resin film. The thickness of the polarizer may be 5 탆 to 100 탆, specifically 5 탆 to 50 탆. In the above range, it can be used for a polarizing plate.

The optical film may be formed on one side or both sides of the polarizer to protect the polarizer.

The optical film may be selected from the group consisting of a cellulose resin such as triacetyl cellulose (TAC), a polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, a cyclic olefin polymer , Polycarbonate resin, polyether sulfone resin, polysulfone resin, polyamide resin, polyimide resin, non-cyclic-polyolefin resin, polymethyl methacrylate resin Based resin, a polyvinyl alcohol-based resin, a polyvinyl chloride-based resin, and a polyvinylidene chloride-based resin. The optical film may have a thickness of 5 占 퐉 to 200 占 퐉, specifically 10 占 퐉 to 150 占 퐉, more specifically, 50 占 퐉 to 120 占 퐉. In the above range, it can be used for a polarizing plate. Preferably, the optical film may be a PET film, a COP film, or a TAC film. Preferably, the COP film may comprise a COP film produced by a solution casting method.

The adhesive composition for a polarizing plate of the present invention is a photocurable composition. Therefore, it is applied to an optical film, a polarizer is laminated and photo-cured to form an adhesive layer. The thickness of the adhesive layer may be 0.5 占 퐉 to 10 占 퐉, for example, 1 占 퐉 to 10 占 퐉. In the above range, it can be used for a polarizing plate.

An optical display device according to an embodiment of the present invention may include a polarizing plate according to embodiments of the present invention. The optical display device may include an adhesive layer formed of the adhesive composition for a polarizing plate of the present invention. The optical display device may be a liquid crystal display device, but is not limited thereto.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to embodiments of the present invention. However, the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Specific specifications of the components used in Examples and Comparative Examples are as follows.

A: alicyclic epoxy compound: cycloaliphatic diepoxide (CELLOXIDE 2021P, Daicel) alicyclic bifunctional epoxy compound

B: aromatic epoxy compound: phenylglycidyl ether (EX-141, Nagase Chemtex)

C: aromatic epoxy compound: resorcinol diglycidyl ether (EX-201, Nagase Chemtex)

D: (meth) acrylate compound: 4-hydroxybutyl acrylate (100%, manufactured by Osaka Organic)

E: (meth) acrylate compound: 2-hydroxyethyl acrylate (100%, available from Osaka Organic Co.,

F: photoacid generator: diphenyl 4- (phenylthio) phenylsulfonium hexafluorophosphate (CPI-100P, San-Apro)

G: Photoradical initiator: 1-Hydroxy-cyclohexyl phenyl ketone (Irgacure-184, BASF)

H: neopentyl glycol diglycidyl ether: EX-211, manufactured by Nagase Chemtex Co., Ltd.

Example One

, 50 parts by weight of an alicyclic epoxy compound, 20 parts by weight of a C aromatic epoxy compound, 30 parts by weight of a D (meth) acrylate compound, 2 parts by weight of an F photo acid generator and 1 part by weight of a G photo radical initiator, A composition was prepared.

Example  2 to Example  8

A composition for an adhesive layer was prepared in the same manner as in Example 1, except that the kind or content of each component was changed to the following Table 1 (unit: parts by weight).

Comparative Examples 1 to 6

A composition for an adhesive layer was prepared in the same manner as in Example 1, except that the kind or content of each component was changed to the following Table 1 (unit: parts by weight).

A B C D E F G H Example 1 50 - 20 30 - 2 One - Example 2 50 10 10 30 - 5 One - Example 3 70 - 10 20 - 3 3 - Example 4 30 10 20 40 - 2 One - Example 5 40 10 10 40 - 2 One - Example 6 30 15 15 20 20 2 One - Example 7 60 5 20 15 - 4 One - Example 8 60 5 25 - 10 One One - Comparative Example 1 15 - - 85 - 2 One - Comparative Example 2 60 - 40 - - 2 - - Comparative Example 3 65 - 5 30 - 2 One - Comparative Example 4 35 - 35 30 - 2 One - Comparative Example 5 50 - - 30 - 2 One 20 Comparative Example 6 50 20 - 30 - 2 One -

The properties of the compositions for the adhesive layer of Examples and Comparative Examples were evaluated in the following Table 2 and the results are shown in Table 2 below.

(1) Adhesion: A polyvinyl alcohol film having a thickness of 60 탆 (degree of saponification: 99.5, degree of polymerization: 2000) was immersed in a 0.3% iodine aqueous solution to be polished and then stretched to give a draw ratio of 5.7. Subsequently, the stretched substrate film was immersed in a boric acid solution of 3% concentration and an aqueous potassium iodide solution of 2% to perform color correction, and dried at 50 DEG C for 4 minutes to prepare a polarizer (thickness 23 mu m).

TAC film (Fuji, thickness: 60 탆) was used as a polarizer protective film. The TAC film was saponified and corona treated at 250 mJ / cm < ^{2 &} gt ;.

COP film 1 (Konica, thickness: 40 탆, manufactured by solution casting method) was corona treated at a surface of 250 mJ / cm ² and used as a polarizer protective film.

One side of the COP film 2 (Zeon, Zeoner, thickness: 50 탆, manufactured by the melt casting method) was corona treated at 250 mJ / cm ² and used as a polarizer protective film.

TAC film was coated with the composition for the adhesive layer to the COP film 1 each in a thickness 2㎛ and adhering the polarizer prepared above, temperature 22 ~ 25 ℃, humidity 20 to 60% by lamination in an environment ^{Metal halide lamp 400mW / cm 2,} 1000 mJ / cm < ² > to prepare a polarizing plate.

The prepared polarizing plate was cut into a length x width (100 mm x 25 mm), and a cutter cutter was inserted between the optical film at the end of the polarizing plate and the polarizer. A mark indicating that the edge of the optical film did not enter between the optical film and the polarizer was evaluated as " A ", a mark with a small amount of the mark was marked " A ";

TAC film and COP film 2 were used.

(2) Water resistance: A polarizing plate was produced in the same manner as in (1). The polarizer was cut into length x width (50 mm x 50 mm) and immersed in a thermostat with water at 60 DEG C for 6 hours. The water resistance was evaluated by the decolorizing length of the polarizer edge. ⊚ in the case of no discoloration, ∘ in the case of discoloration exceeding 0 mm and less than 2 mm, and × in case of discoloration of 2 mm or more.

(3) Thermal shock crack length (unit: mm): The crack resistance of the polarizing plate under thermal shock was evaluated. A polarizing plate was prepared in the same manner as in (1). A polarizing plate having a length x width (50 mm x 50 mm) was laminated on a glass plate to prepare a sample. The sample was allowed to stand at -40 占 폚 for 30 minutes, elevated from -40 占 폚 to 85 占 폚, and left at 85 占 폚 for 30 minutes. The sample was visually checked for cracks in the MD of the polarizer in the reflection mode under the fluorescent lamp and the back light mode. The maximum length of cracks was evaluated.

(4) bs: The polarizing plates of Examples and Comparative Examples were cut into a length x width (30 mm x 30 mm) to prepare specimens. The specimen was mounted in a measuring instrument V-7100 (Jasco), and the COP film 1 or the COP film 2 in the specimen was mounted so as to face the surface where the light was emitted. After mounting, the measurement device was driven to evaluate the bs value measured in the MD direction and the TD direction of the polarizer as shown in the following equation. <Expression> bs value = [(MD direction bs value + TD direction bs value) / 2]

Adhesiveness Water resistance Thermal shock
Crack length bs TAC film COP
Film 1 COP
Film 2 Example 1 ◎ ○ ○ ○ 1.4 3.0 Example 2 ◎ ○ ◎ ○ 1.5 3.0 Example 3 ◎ ○ ○ ◎ 2.1 3.1 Example 4 ◎ ○ ◎ ◎ 0.9 2.9 Example 5 ◎ ◎ ○ ◎ 2.2 3.0 Example 6 ◎ ◎ ◎ ◎ 1.8 3.0 Example 7 ◎ ◎ ◎ ◎ 1.8 3.0 Example 8 ◎ ◎ ◎ ◎ 2.2 2.9 Comparative Example 1 × △ ○ × 0.9 3.1 Comparative Example 2 △ × △ × 50 3.2 Comparative Example 3 ○ × △ △ 40 3.0 Comparative Example 4 △ ○ ○ ○ 35 3.1 Comparative Example 5 ○ × ○ ○ 2.0 3.0 Comparative Example 6 ○ × △ ○ 2.8 2.9

As shown in Table 2, the adhesive composition for a polarizing plate of the present invention was excellent in adhesion to both the TAC film and the COP film. In particular, the adhesive composition for a polarizing plate of the present invention was excellent in adhesion to both the COP film produced by the melt casting method and the COP film produced by the solution casting method. In addition, the adhesive composition for a polarizing plate of the present invention can block or minimize cracking of a polarizer upon thermal shock, and has excellent water resistance.

On the other hand, Comparative Example 2, which does not include a (meth) acrylate-based compound, has a problem that the adhesive force between the PVA and the protective film is lowered. Further, Comparative Examples 1, 3 and 4, in which the glycidyl ether compound of an aromatic compound having two or more hydroxyl groups was out of the content range of the present invention, showed a decrease in crack resistance in thermal shock, There is a problem that a low adhesive strength is generated. Comparative Example 5, which includes aliphatic diglycidyl ether instead of aromatic diglycidyl ether, also produces low adhesion to the cast COP film. Comparative Example 6 containing an aromatic monoglycidyl ether instead of an aromatic diglycidyl ether had a problem that a low adhesive force was generated with respect to the COP series film.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (13)

(Meth) acrylate-based compound, and a photoinitiator,
Wherein the epoxy-based compound comprises an alicyclic epoxy compound and an aromatic epoxy compound, and the aromatic epoxy compound is a polyglycidyl ether of an aromatic compound in a total amount of the epoxy compound and the (meth) And 10 to 30 parts by weight based on 100 parts by weight of the adhesive composition.
The adhesive composition for a polarizing plate according to claim 1, wherein the polyglycidyl ether of the aromatic compound comprises a diglycidyl ether of an aromatic compound having at least two phenolic hydroxyl groups.
The adhesive composition for a polarizing plate according to claim 1, wherein the polyglycidyl ether of the aromatic compound comprises at least one of resorcinol diglycidyl ether, hydroquinone diglycidyl ether, and catechol diglycidyl ether.
The adhesive composition for a polarizing plate according to claim 1, wherein the polyglycidyl ether of the aromatic compound is contained in an amount of 10 to 50 parts by weight per 100 parts by weight of the epoxy compound.
The epoxy resin composition according to claim 1, wherein the alicyclic epoxy compound comprises 20 to 80 parts by weight of a bifunctional alicyclic epoxy compound in 100 parts by weight of the total of the epoxy compound and the (meth) acrylate compound. Adhesive composition for a polarizing plate.
The adhesive composition for a polarizing plate according to claim 1, wherein the aromatic epoxy compound further comprises a monoglycidyl ether of an aromatic compound.
The adhesive composition for a polarizing plate according to claim 6, wherein the monoglycidyl ether of the aromatic compound comprises at least one of phenyl glycidyl ether, cresyl glycidyl ether, nonylphenyl glycidyl ether.
The adhesive composition for a polarizing plate according to claim 1, wherein the (meth) acrylate-based compound comprises a monofunctional (meth) acrylate-based compound having at least one hydroxyl group.
The adhesive composition for a polarizing plate according to claim 1, wherein the (meth) acrylate compound is contained in an amount of 5 to 60 parts by weight based on 100 parts by weight of the total of the epoxy compound and the (meth) acrylate compound.
The polarizing plate according to claim 1, wherein the polarizing plate including the adhesive layer formed of the adhesive composition for a polarizing plate is left at -40 캜 for 30 minutes, raised from -40 캜 to 85 캜 and left at 85 캜 for 30 minutes, cycle, and the maximum value of the machine direction (MD) crack length of the polarizer when the thermal shock is applied is 3 mm or less.
A polarizer, and an optical film formed on at least one side of the polarizer,
Wherein the optical film is laminated by an adhesive layer formed by the adhesive composition for a polarizing plate according to any one of claims 1 to 10.
12. The polarizing plate according to claim 11, wherein the polarizing plate has a color coordinate bs value of 3 or less.
An optical display device comprising the polarizing plate of claim 11.