KR102301278B1 - Adhesive composition for polarizing plate, polarizing plate formed from the same and optical display apparatus comprising the same - Google Patents

Abstract

An epoxy-based compound, a (meth)acrylate-based compound, and a photoinitiator, wherein the epoxy-based compound includes a non-ester-type, bifunctional or more alicyclic epoxy-based compound that does not contain an ester group, and the (meth)acrylate An adhesive composition for a polarizing plate, a polarizing plate, and an optical display device are provided.

Description

Adhesive composition for a polarizing plate, a polarizing plate formed therefrom, and an optical display device comprising the same

The present invention relates to an adhesive composition for a polarizing plate, a polarizing plate including an adhesive layer for a polarizing plate formed therefrom, and an optical display device including the same. More specifically, the present invention improves the discoloration resistance and water resistance of the polarizer at high temperature and high humidity, and has excellent processability and optical transparency due to a fast curing rate, which can provide a polarizing plate with excellent adhesion to a protective film, for a polarizing plate It relates to an adhesive composition, a polarizing plate including an adhesive layer for a polarizing plate formed therefrom, and an optical display device including the same.

The liquid crystal display includes a liquid crystal panel and a polarizing plate formed on both surfaces of the liquid crystal panel, respectively. The polarizing plate includes a polarizer and a protective film formed on at least one surface of the polarizer.

The polarizer may be manufactured by performing a stretching process and an adsorption process of a dichroic dye such as iodine on a polyvinyl alcohol-based film. However, a dichroic dye such as iodine is adsorbed to the polyvinyl alcohol-based film. Therefore, when the polarizing plate is left at high temperature and high humidity for a long time, the polarization degree of the polarizing plate may be lowered by decolorization of the polarizer by desorption of a dichroic dye such as iodine from the polyvinyl alcohol-based film. When a dichroic dye such as iodine is decolorized from the polarizer, the degree of polarization is lowered, so that the polarization function cannot be properly performed in the optical display device. In the process of manufacturing the polarizer, a complementary color process using boric acid or the like may be performed. However, the complementary color process has a limit in preventing desorption of the dichroic dye and discoloration of the polarizer due to this.

Background art of the present invention is described in Japanese Patent Application Laid-Open No. 2008-260879 and the like.

An object of the present invention is to provide an adhesive composition for a polarizing plate that can provide a polarizing plate having excellent water resistance.

Another object of the present invention is to provide an adhesive composition for a polarizing plate that can provide color resistance at high temperature and high humidity of the polarizer.

Another object of the present invention is to provide an adhesive composition for a polarizing plate capable of providing a polarizing plate having excellent processability and excellent optical transparency due to a fast curing rate.

Another object of the present invention is to provide an adhesive composition for a polarizing plate capable of providing a polarizing plate having excellent adhesion to a protective film.

Another object of the present invention is to provide an adhesive composition for a polarizing plate capable of providing a polarizing plate having a low color value (bs value).

The adhesive composition for a polarizing plate of the present invention includes an epoxy-based compound, a (meth)acrylate-based compound, and a photoinitiator, and the epoxy-based compound includes a non-ester-type, bifunctional or more alicyclic epoxy compound that does not contain an ester group. And, the (meth) acrylate-based compound may include a (meth) acrylate-based compound having a hydroxyl group and an aromatic group.

The non-ester-type, bifunctional or more alicyclic epoxy compound that does not contain an ester group may have an epoxycyclopentyl group or an epoxycyclohexyl group.

The non-ester type, bifunctional or more alicyclic epoxy-based compound may be represented by the following Chemical Formula 1, the following Chemical Formula 2, or the following Chemical Formula 3:

<Formula 1>

(In Formula 1, R ¹ , R ² are each independently an alkyl group having 1 to 10 carbon atoms, a is an integer of 0 to 2, and b is an integer of 0 to 1)

<Formula 2>

(In Formula 2, R ³ is an alkyl group having 1 to 10 carbon atoms, and c is an integer of 0 to 1)

<Formula 3>

(In Formula 3, R ⁴ and R ⁵ are each independently an alkyl group having 1 to 10 carbon atoms, d is an integer from 0 to 2, and e is an integer from 0 to 1).

The non-ester type, bifunctional or more alicyclic epoxy-based compound may be included in an amount of 40% to 90% by weight of the total of the epoxy-based compound and the (meth)acrylate-based compound.

The epoxy compound may not include an ester-type alicyclic or more alicyclic epoxy compound.

The epoxy-based compound may not include an epoxy-based compound having a non-ester-type, bifunctional or higher glycidyl group.

The (meth)acrylate-based compound having a hydroxyl group and an aromatic group may include 2-hydroxy-3-phenoxypropyl (meth)acrylate or an isomer thereof.

The (meth)acrylate-based compound having the hydroxyl group and the aromatic group may be included in an amount of 50% to 100% by weight of the total of the (meth)acrylate-based compound.

The (meth)acrylate-based compound may further include a (meth)acrylate-based compound having a non-aromatic hydroxyl group.

Among the total of the epoxy-based compound and the (meth)acrylate-based compound, the epoxy-based compound may be included in an amount of 40% to 90% by weight, and the (meth)acrylate-based compound may be included in an amount of 10% to 60% by weight.

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

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 polarizing plate may have a color coordinate bs value of 4.0 or less.

The polarizing plate was prepared by cutting the polarizing plate into a square of length x width (3 cm x 3 cm) to prepare a sample, leaving the sample in a constant temperature and humidity chamber at 85 °C and relative humidity of 85% for 250 hours, and then the constant temperature and humidity The sample is taken out from the chamber and left at 25° C. for 1 hour, and then, the maximum length from the distal end of the polarizer to the discolored part may be 2 mm or less.

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 capable of providing a polarizing plate having excellent water resistance.

The present invention provides an adhesive composition for a polarizing plate capable of providing the polarizer's discoloration resistance at high temperature and high humidity.

The present invention provides an adhesive composition for a polarizing plate capable of providing a polarizing plate having excellent processability and excellent optical transparency due to a fast curing rate.

The present invention provides an adhesive composition for a polarizing plate capable of providing a polarizing plate having excellent adhesion to a protective film.

Another object of the present invention is to provide an adhesive composition for a polarizing plate capable of providing a polarizing plate having a low color value (bs value).

Hereinafter, embodiments of the present application will be described in more detail with reference to the accompanying embodiments. However, the technology disclosed in the present application is not limited to the embodiments described herein and may be embodied in other forms. However, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete and the spirit of the present application may be sufficiently conveyed to those skilled in the art.

As used herein, “(meth)acryl” means acrylic and/or methacrylic.

As used herein, the range "X to Y" means "X or more and Y or less (X≤range ≤Y)".

The inventor of the present invention, in the adhesive composition for a polarizing plate for adhering a polarizing plate and a protective film, a (meth) acrylate-based compound having a non-ester-type, bifunctional or more cycloaliphatic epoxy compound that does not contain an ester group, and a hydroxyl group and an aromatic group When all of them were included, it was confirmed that the discoloration resistance and water resistance of the polarizer could be improved at high temperature and high humidity, and the present invention was completed. As used herein, "ester group" means *-C (=O)-O-* (* means a linking site).

In one embodiment, a polarizing plate comprising an adhesive layer formed of the adhesive composition for a polarizing plate of the present invention is prepared by cutting the polarizing plate into a square of length x width (3cm x 3cm), and the prepared sample is subjected to 85 ° C. and 85 relative humidity. % in a constant temperature and humidity chamber for 250 hours, then the sample is taken out from the chamber and left at 25° C. for 1 hour, then the maximum length from the tip of the polarizer to the discolored part is 2 mm or less, e.g. For example, it may be less than 1.5 mm. In the above range, the polarizing plate may have excellent discoloration resistance at high temperature and high humidity, and thus the reliability of the polarizing plate may be excellent.

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 includes an epoxy-based compound, a (meth)acrylate-based compound, and a photoinitiator, and the epoxy-based compound is a non-ester type that does not contain an ester group and includes a bifunctional or more alicyclic epoxy compound, The (meth)acrylate-based compound may include a (meth)acrylate-based compound having a hydroxyl group and an aromatic group. As a result, even if the polarizing plate is left for a long period of time at high temperature and high humidity after the polarizing plate is manufactured, the polarizer has excellent discoloration resistance and water resistance, and excellent adhesion after immersion.

An adhesive composition comprising a (meth)acrylate-based compound having a hydroxyl group and an aromatic group and an ester-type bifunctional or more alicyclic epoxy-based compound cannot be used as a polarizing plate because its discoloration resistance is significantly lowered and a sufficient degree of polarization is not obtained. An adhesive composition comprising a (meth)acrylate-based compound having a hydroxyl group without an aromatic group in a non-ester-type alicyclic epoxy-based compound having a bifunctional or higher function has discoloration and water resistance under high temperature and high humidity conditions (85°C and 85% relative humidity) There was a problem of degradation.

The epoxy-based compound may include a non-ester type and a bifunctional or more alicyclic epoxy-based compound. The non-ester type and bi- or more functional alicyclic epoxy-based compound may improve the discoloration resistance of the polarizing plate at high temperature and high humidity. The non-ester type and bifunctional or more alicyclic epoxy compound may be included in the adhesive composition alone or in a mixture of two or more.

The non-ester type and more than bifunctional alicyclic epoxy-based compound should contain two or more, preferably two, alicyclic epoxy groups. In this case, the adhesiveness of the adhesive layer formed of the adhesive composition for a polarizing plate may be improved. The non-ester type epoxy compound having a bifunctional or more glycidyl group may have low reactivity of the adhesive composition and poor water resistance and discoloration resistance.

The "alicyclic epoxy group" refers to a functional group in which a carbon-carbon single bond constituting an alicyclic ring is epoxidized. The number of carbon atoms of the alicyclic ring constituting the alicyclic epoxy group is 5 to 7, preferably 5 to 6, and may be an epoxycyclopentyl group or an epoxycyclohexyl group.

In one embodiment, the non-ester type and bifunctional or more alicyclic epoxy compound may be a compound in which two or more alicyclic epoxy groups share carbon constituting an alicyclic epoxy group with each other. For example, it may be an epoxy-based compound of Formula 1 or Formula 2 below.

<Formula 1>

(In Formula 1, R ¹ , R ² are each independently an alkyl group having 1 to 10 carbon atoms, a is an integer of 0 to 2, and b is an integer of 0 to 1)

<Formula 2>

(In Formula 2, R ³ is an alkyl group having 1 to 10 carbon atoms, and c is an integer of 0 to 1)

In another embodiment, the non-ester type and bifunctional or more alicyclic epoxy compound may be a compound in which two or more alicyclic epoxy groups are connected to each other by an alicyclic ring. For example, it may be an epoxy-based compound of Formula 3 below.

<Formula 3>

(In Formula 3, R ⁴ and R ⁵ are each independently an alkyl group having 1 to 10 carbon atoms, d is an integer from 0 to 2, and e is an integer from 0 to 1).

The non-ester type and the bifunctional or more alicyclic epoxy compound is 40 wt% to 90 wt% of the total of the non-ester type and the bifunctional or more functional alicyclic epoxy compound and the (meth)acrylate compound, preferably It may be included in an amount of 50% by weight to 80% by weight. In the above range, the polarizer may have excellent discoloration resistance at high temperature and high humidity, and excellent adhesion after immersion.

In one embodiment, the epoxy-based compound may include substantially no epoxy-based compound having an aromatic ring. Even if the epoxy-based compound having an aromatic ring is not included, the light transmittance of the polarizing plate can be increased by increasing the refractive index of the adhesive layer formed of the adhesive composition for a polarizing plate by the (meth)acrylate-based compound having a hydroxyl group and an aromatic group, and the polarizing plate adhesive composition It may be possible to shorten the curing time of When the epoxy-based compound having an aromatic ring is included, the curing time of the adhesive composition may be prolonged, and thus fairness may be deteriorated. The "substantially free" means that the content of the epoxy-based compound having an aromatic ring in the epoxy-based compound is less than 0.1% by weight, preferably 0% by weight or more and less than 0.1% by weight, most preferably 0% by weight. can

In one embodiment, the epoxy-based compound may not substantially include an epoxy-based compound having a non-ester type and a glycidyl group having a bifunctional or higher function. The "substantially free" means that the content of the non-ester type epoxy compound having a bifunctional or more glycidyl group in the epoxy compound is less than 0.1% by weight, preferably 0% by weight or more and less than 0.1% by weight. , most preferably 0% by weight.

In one embodiment, the epoxy-based compound may not include an ester-type alicyclic or more alicyclic epoxy compound. In the case of containing an ester-type alicyclic epoxy-based compound having a bifunctional or higher function, there is a problem of lowering water resistance due to hydrolysis by water or acid.

The (meth)acrylate-based compound may include a (meth)acrylate-based compound having a hydroxyl group and an aromatic group. The (meth)acrylate-based compound having a hydroxyl group and an aromatic group improves the discoloration resistance of the polarizing plate at high temperature and high humidity, and increases the refractive index of the adhesive layer without reducing the curing rate of the adhesive composition for a polarizing plate, thereby increasing the light transmittance of the polarizing plate. have.

In one embodiment, the refractive index of the adhesive layer formed of the adhesive composition may be 1.45 to 1.55, for example, 1.46 to 1.54.

In one embodiment, the polarizing plate may have a light transmittance of 40% or more, for example, 41% to 45% in a visible light region (eg, a wavelength of 380 nm to 780 nm).

The (meth)acrylate-based compound having a hydroxyl group and an aromatic group includes one (meth)acrylate group, and a monofunctional (meth)acrylate-based compound having a hydroxyl group and an aromatic group in the ester portion of the (meth)acrylate. can In one embodiment, the (meth)acrylate-based compound having a hydroxyl group and an aromatic group may be a monofunctional (meth)acrylate having a linear or branched C1-C10 alkyl group substituted with a hydroxyl group and an aryloxy group. have.

For example, the (meth)acrylate-based compound having a hydroxyl group and an aromatic group may include, but is not limited to, 2-hydroxy-3-phenoxypropyl (meth)acrylate or an isomer thereof.

The (meth)acrylate-based compound having a hydroxyl group and an aromatic group may be included in an amount of 50% to 100% by weight of the total of the (meth)acrylate-based compound. In the above range, the polarizer may have excellent discoloration resistance at high temperature and high humidity, and excellent adhesion after immersion.

The (meth)acrylate-based compound may further include a (meth)acrylate-based compound having a hydroxyl group without an aromatic group (non-aromatic) in addition to the (meth)acrylate-based compound having a hydroxyl group and an aromatic group. When the (meth)acrylate-based compound having a hydroxyl group without an aromatic group is further added, the photocuring reaction is excellent.

The (meth)acrylate-based compound having a hydroxyl group without an aromatic group may include a linear or branched C1-C10 (meth)acrylate compound substituted with a hydroxyl group. For example, it may be 2-hydroxyethyl (meth) acrylate, 2 or 3-hydroxypropyl (meth) acrylate, 2-, 3- or 4-hydroxybutyl (meth) acrylate, etc. It is not limited thereto.

The (meth)acrylate-based compound having a hydroxyl group without an aromatic group (non-aromatic) is 50 wt% or less, for example, 0 wt% to 50 wt%, 1 wt% of the total of the (meth)acrylate-based compounds to 50% by weight.

Of the total of the epoxy-based compound and the (meth)acrylate-based compound, the epoxy-based compound is 40 wt% to 90 wt%, preferably 50 wt% to 80 wt%, and the (meth)acrylate-based compound is 10 Weight% to 60% by weight, preferably 20% to 50% by weight may be included. Within the above range, the polarizer may have excellent adhesion to the protective film, and excellent discoloration resistance and water resistance.

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

The photoacid generator is a photocationic initiator, and an onium salt containing a cation and an anion may be used. Specifically, the cation is triarylsulfonium such as triphenylsulfonium, diphenyl-4-(phenylthio)phenylsulfonium, diphenyl-4-thiophenoxyphenylsulfonium, bis[4-(diphenylsulfonium) phonio)phenyl]sulfide, iodonium, etc. are mentioned. Specifically, the anion is hexafluorophosphate (PF ₆ ^- ), tetrafluoroborate (BF ₄ ^- ), hexafluoroantimonate (SbF ₆ ^- ), hexafluoroarsenate (AsF ₆ ^- ), hexa and chloroantimonate (SbCl ₆ ⁻ ). Preferably, the photoacid generator may use a sulfonium-based agent. By using a sulfonium-based photoacid generator, the bs value of the polarizing plate may be lowered.

The photoacid generator may be included in an amount of 0.1 parts by weight to 10 parts by weight, for example, 1 part by weight to 6 parts by weight, based on 100 parts by weight of the total of the epoxy-based compound and the (meth)acrylate-based compound. In the above range, the epoxy-based compound may be sufficiently cured, and adhesion deterioration may not occur, and a residual amount of the photo-acid generator may remain, thereby reducing the transparency of the adhesive layer or preventing the bleed-out of the photo-acid generator.

When the photo-radical initiator is used together with the photo-acid generator, the color coordinate bs value of the adhesive layer may be lowered, and the (meth)acrylate-based compound may be cured. As the photoinitiator, those commonly known to those skilled in the art may be used. Specifically, the photoinitiator may be one or more of phosphorus-based, triazine-based, acetophenone-based, benzophenone-based, benzoin-based, and oxime-based. A polarizing plate including an adhesive layer formed of the adhesive composition for a polarizing plate of the present invention may have a color coordinate bs value of 4.0 or less, for example, 3.1 or less, or 2 to 3.1. In the above range, when the polarizing plate is used as an optical display device, the yellow color is not recognized and thus the visibility is excellent.

The radical photoinitiator may be included in an amount of 0.1 to 10 parts by weight, for example, 1 to 7 parts by weight, based on 100 parts by weight of the total of the epoxy-based compound and the (meth)acrylate-based compound. In the above range, the (meth)acrylate-based compound may be sufficiently cured, and a residual amount of the photo-radical initiator may remain, thereby reducing the transparency of the adhesive layer or preventing the bleed-out of the photo-radical initiator.

Although the adhesive composition for polarizing plates may contain a solvent, it may be a solvent-free adhesive composition which does not contain a solvent. By using the solvent-free adhesive composition, it is possible to minimize the effect on the optical film.

The adhesive composition for a polarizing plate may further include conventional additives such as antioxidants, adhesion promoters, antistatic agents, leveling agents, defoamers, and UV absorbers, thereby producing the effect of additives.

The adhesive composition for a polarizing plate may have a viscosity of 20 cps to 100 cps at 25°C. In the above range, the 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 a protective film formed on at least one surface of the polarizer, and the protective film may be adhered to the polarizer by an adhesive layer formed by the adhesive composition for a polarizing plate of the present invention.

The polarizer may polarize 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 polarizer in which at least one of iodine and a dichroic dye is adsorbed to a polyvinyl alcohol-based resin film. In another embodiment, the polarizer may be a polyene-based polarizer prepared by dehydrating a polyvinyl alcohol-based resin film. The polarizer may have a thickness of 5 μm to 100 μm, specifically 5 μm to 50 μm. Within the above range, it can be used for a polarizing plate.

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

The protective film is a cellulose-based resin such as triacetyl cellulose (TAC), a polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, and amorphous cyclic polyolefin (cyclic olefin polymer). , COP), including cyclic polyolefin-based resins, polycarbonate-based resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethylmethacryl The film may include at least one of a polyacrylate-based resin including a rate resin, a polyvinyl alcohol-based resin, a polyvinyl chloride-based resin, and a polyvinylidene chloride-based resin. The protective film may have a thickness of 5 μm to 200 μm, specifically 10 μm to 150 μm, and more specifically 50 μm to 120 μm. Within the above range, it can be used for a polarizing plate. Preferably, the protective film may be a PET film, a COP film, or a TAC film.

The adhesive composition for a polarizing plate of the present invention is a photocurable composition. Therefore, it is applied to a protective film, laminated with a polarizer, and photocured to form an adhesive layer. The thickness of the adhesive layer may be 0.5 μm to 10 μm, for example, 1 μm to 10 μm. Within the above range, it can be used for a polarizing plate.

The optical display device according to an embodiment of the present invention may include the polarizing plate according to the 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 through embodiments of the present invention. However, the following examples are provided to help the understanding of the present invention, and the scope of the present invention is not limited thereto.

Hereinafter, specific specifications of the components used in Examples and Comparative Examples are as follows

A: non-ester type bifunctional alicyclic epoxy compound (THI-DE, JXTG, in Formula 1, a and b are both 0)

B: non-ester-type bifunctional alicyclic epoxy compound (DE-102, JXTG, d and e are all 0 in Formula 3)

C: Ester-type bifunctional alicyclic epoxy compound (Celloxide 2021P, Daicel)

D: non-ester type bifunctional glycidyl epoxy compound (EX-212, Nagase Chemtex)

E: Bifunctional aromatic epoxy compound (YD-128, Kukdo Chemical)

F: (meth) acrylate-based compound having a hydroxyl group and an aromatic group (DA-141, Nagase Chemtex)

G: (meth)acrylate-based compound having a hydroxyl group and not an aromatic group (4-hydroxybutyl acrylate, 100%, Osaka Organic)

H: Photoacid generator (diphenyl 4- (phenylthio) phenyl sulfonium hexafluorophosphate, CPI-100P, San-Apro)

I: Photoradical initiator: 1-hydroxy-cyclohexylphenyl ketone (Irgacure-184, BASF)

Example One

A: 50 parts by weight of an alicyclic epoxy compound, F: 50 parts by weight of a (meth) acrylate-based compound, H: 2 parts by weight of a photoacid generator, I: 1 part by weight of a photo-radical generator to prepare an adhesive composition for a polarizing plate did

Example 2 to Example 8

In Example 1, an adhesive composition for a polarizing plate was prepared in the same manner as in Example 1, except that the type or content of each component was changed as shown in Table 1 (unit: parts by weight).

comparative example 1 to comparative example 5

In Example 1, an adhesive composition for a polarizing plate was prepared in the same manner as in Example 1, except that the type or content of each component was changed as shown in Table 1 (unit: parts by weight).

Epoxy compound (Meth) acrylate compound photoinitiator A B C D E F G H I Example 1 50 - - - - 50 - 2 One Example 2 80 - - - - 20 - 2 One Example 3 - 50 - - - 50 - 2 One Example 4 50 - - - - 50 - 5 One Example 5 50 - - - - 50 - 3 3 Example 6 30 30 - - - 40 - 2 One Example 7 - 80 - - - 20 - 2 One Example 8 30 30 - - - 20 20 2 One Comparative Example 1 - - 50 - - - 50 2 One Comparative Example 2 - - 50 - - 50 - 2 One Comparative Example 3 - - - 50 - 50 - 2 One Comparative Example 4 - - - - 50 50 - 2 One Comparative Example 5 50 - - - - - 50 2 One

For the adhesive composition for a polarizing plate of Examples and Comparative Examples, a polarizing plate was prepared by the following method, the physical properties of the following Table 2 were evaluated, and the results are shown in Table 2 below.

Polarizer manufacturing

A 60 μm thick polyvinyl alcohol film (saponification degree: 99.5, degree of polymerization: 2000) was immersed in 0.3% iodine aqueous solution and dyed, and then stretched to a draw ratio of 5.7, and the stretched base film was mixed with a 3% concentration of boric acid solution. It may be a polarizer (thickness 23 μm) manufactured by immersing in an aqueous solution of potassium iodide and 2% potassium iodide for color correction, followed by drying at 50° C. for 4 minutes.

TAC film (Fuji, thickness: 80㎛) was saponified, ^{and corona-treated at 250mJ/cm 2} , and used as a polarizer protective film. One side of the COP film (Konica, thickness: 30㎛) ^{was corona-treated at 250mJ/cm 2} and used as a polarizer protective film.

To each of the TAC film and the COP film, the adhesive composition for a polarizing plate prepared in Examples and Comparative Examples was applied to a thickness of 2 to 3 μm, and the prepared polarizers were laminated, respectively, at a temperature of 22 to 25° C., and a relative humidity of 20 to 60%. It was laminated in an environment and photocured under the conditions of metal halide lamp 400mW/cm2 and 1000mJ/cm2, and a TAC film, an adhesive layer (thickness 3㎛), a polarizer, an adhesive layer (3㎛ thickness), a polarizing plate laminated in the order of COP film was prepared.

(1) Adhesiveness: The prepared polarizing plate was cut to length x width (100mm x 25mm), and a cutter blade was inserted between the polarizer and the protective film at the end of the polarizing plate. It was evaluated as ◎ when the tip of the knife did not enter between the protective film and the polarizer, ○ when the tip was slightly inserted, △ when the tip was slightly inserted but had a certain strength, so that the optical film was torn in the middle, and x was evaluated when the tip was easily inserted.

(2) Decolorization resistance (unit: mm): A sample was prepared by cutting the prepared polarizing plate into a square of length x width (3cm x 3cm), and the prepared sample was subjected to a constant temperature and humidity chamber at 85°C/relative humidity of 85%. was left for 250 hours. Then, the sample was taken out of the chamber and left at 25° C. for 1 hour. Then, the maximum length from the distal end of the polarizer to the discolored portion was measured.

(3) bs value: The prepared polarizing plate was cut to length x width (30 mm x 30 mm) to prepare a specimen. The specimen was mounted in a measuring device V-7100 (Jasco), but the COP film side of the specimen was mounted so that the light was emitted. After mounting, the measuring device was driven to measure the bs value of the polarizing plate.

adhesive discoloration resistance bs value TAC film side COP film side Example 1 ◎ ○ 1.1 3.0 Example 2 ◎ ○ 0.5 3.0 Example 3 ◎ ○ 1.2 3.1 Example 4 ◎ ○ 1.4 2.9 Example 5 ◎ ◎ 1.3 3.0 Example 6 ◎ ◎ 1.3 3.0 Example 7 ◎ ◎ 0.6 3.0 Example 8 ◎ ◎ 1.4 2.9 Comparative Example 1 ◎ ○ 4.8 2.9 Comparative Example 2 ○ ○ 4.5 3.1 Comparative Example 3 △ X 3.6 3.0 Comparative Example 4 X △ 3.9 3.1 Comparative Example 5 △ △ 3.0 3.0

As shown in Table 2, the adhesive composition for a polarizing plate of the present invention has excellent adhesion to the protective film, excellent water resistance, and provided the polarizer's discoloration resistance at high temperature and high humidity, and a polarizing plate with a low color value (bs value). provided.

On the other hand, Comparative Example 1 and Comparative Example 1 comprising a (meth)acrylate-based compound having a hydroxyl group and not an aromatic group and a (meth)acrylate-based compound having a hydroxyl group and an aromatic group in the ester-type bifunctional alicyclic epoxy compound Example 2 had poor discoloration resistance. Comparative Examples 3 and 4, which do not contain a non-ester type, bifunctional or more alicyclic epoxy compound, even including a (meth)acrylate-based compound having a hydroxyl group and an aromatic group had poor adhesion and poor discoloration resistance . Comparative Example 5 including a (meth)acrylate-based compound having a hydroxyl group without an aromatic group in a non-ester-type alicyclic epoxy-based compound having a bifunctional or higher function had low discoloration resistance and water resistance.

Simple modifications or changes of the present invention can be easily carried out by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (15)

It contains an epoxy-based compound, a (meth)acrylate-based compound and a photoinitiator,
The epoxy-based compound includes a non-ester-type, bifunctional or more alicyclic epoxy-based compound that does not contain an ester group,
The (meth) acrylate-based compound is an adhesive composition for a polarizing plate comprising a (meth) acrylate-based compound having a hydroxyl group and an aromatic group.
The adhesive composition for a polarizing plate according to claim 1, wherein the non-ester-type, bifunctional or more alicyclic epoxy-based compound that does not contain an ester group has an epoxycyclopentyl group or an epoxycyclohexyl group.
The adhesive composition for a polarizing plate according to claim 1, wherein the non-ester-type, bifunctional or more alicyclic epoxy-based compound is represented by the following Chemical Formula 1, the following Chemical Formula 2, or the following Chemical Formula 3:
<Formula 1>

(In Formula 1, R ¹ , R ² are each independently an alkyl group having 1 to 10 carbon atoms, a is an integer of 0 to 2, and b is an integer of 0 to 1)
<Formula 2>

(In Formula 2, R ³ is an alkyl group having 1 to 10 carbon atoms, and c is an integer of 0 to 1)
<Formula 3>

(In Formula 3, R ⁴ and R ⁵ are each independently an alkyl group having 1 to 10 carbon atoms, d is an integer from 0 to 2, and e is an integer from 0 to 1).
The polarizing plate according to claim 1, wherein the non-ester-type, bifunctional or more alicyclic epoxy-based compound is included in an amount of 40 wt% to 90 wt% of the total of the epoxy-based compound and the (meth)acrylate-based compound. adhesive composition for
The adhesive composition for a polarizing plate according to claim 1, wherein the epoxy-based compound does not include an ester-type alicyclic or more alicyclic epoxy-based compound.
The adhesive composition for a polarizing plate according to claim 1, wherein the epoxy-based compound does not include an epoxy-based compound having a glycidyl group having a bifunctional or higher function of a non-ester type.
The adhesive composition for a polarizing plate according to claim 1, wherein the (meth)acrylate-based compound having a hydroxyl group and an aromatic group includes 2-hydroxy-3-phenoxypropyl (meth)acrylate or an isomer thereof.
The adhesive composition for a polarizing plate according to claim 1, wherein the (meth)acrylate-based compound having a hydroxyl group and an aromatic group is included in an amount of 50% to 100% by weight of the total of the (meth)acrylate-based compound.
The adhesive composition for a polarizing plate according to claim 1, wherein the (meth)acrylate-based compound further comprises a (meth)acrylate-based compound having a non-aromatic hydroxyl group.
The method according to claim 1, wherein, in the total of the epoxy compound and the (meth)acrylate compound, the epoxy compound is 40 wt% to 90 wt%, and the (meth)acrylate compound is 10 wt% to 60 wt% %, the adhesive composition for a polarizing plate.
The adhesive composition for a polarizing plate according to claim 1, wherein the photoinitiator comprises at least one of a photoacid generator and a photoradical initiator.
A polarizer, comprising a protective film formed on at least one surface of the polarizer,
The protective film is a polarizing plate laminated by an adhesive layer formed by the adhesive composition for a polarizing plate according to any one of claims 1 to 11.
The polarizing plate according to claim 12, wherein the polarizing plate has a color coordinate bs value of 4.0 or less.
The method of claim 12, wherein the polarizing plate is prepared by cutting the polarizing plate into a square of length x width (3 cm x 3 cm), and the sample is left in a constant temperature and humidity chamber at 85 °C and 85% relative humidity for 250 hours. , Then, the sample is taken out from the constant temperature and humidity chamber and left at 25° C. for 1 hour, and then the maximum length from the distal end of the polarizer to the discolored part is 2 mm or less, the polarizing plate.
An optical display device comprising the polarizing plate of claim 12 .