KR20160004187A - Adhesive composition and polarizing plate comprising the same - Google Patents

Abstract

The present invention relates to an adhesive composition and a polarizing plate to which a polarizer and a polarizer protection film are coupled by using the adhesive composition. The adhesive composition for the polarizing plate of the present invention has an effect of improving water resistance without degradation of adhesive strength and a polarization degree.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an adhesive composition,

The present invention relates to an adhesive composition and a polarizer in which a polarizer and a polarizer protective film are bonded using the adhesive composition.

The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. The polarizing plate usually has a structure in which a protective film is laminated on both surfaces of a polarizer, and is inserted into a liquid crystal display device. It is also known to provide a protective film on only one side of the polarizer. In most cases, however, the other side is not a simple protective film but a separate function, for example, a layer having an optical function is also bonded together with a protective film.

Currently, an iodine-based film in which iodine is adsorbed to polyvinyl alcohol or a dye-based film in which a dichroic dye is adsorbed and oriented on polyvinyl alcohol is used as a polarizer, and at least an aqueous solution of a polyvinyl alcohol- (TAC) or the like is bonded via an adhesive layer formed by using a protective film (polyvinyl alcohol-based adhesive). However, when the polarizing plate having such a structure is used for a long time under humid heat, There is a problem that the end face of the polarizer is easily peeled off.

Thus, a polarizing plate in which a polarizer (polarizing film) and a protective film are bonded using a polyvinyl alcohol-based adhesive and then heated and dried at a temperature of 90 to 100 ° C to improve the heat and humidity resistance has been proposed. However, The problem that the cross section of the protective film and the polarizer is easily peeled is not solved.

In order to solve such a problem, JP-A-1995-134212 discloses a resin composition comprising an acetoacetyl group-modified polyvinyl alcohol resin, a polyvinyl alcohol resin (crosslinking regulator), glyoxal (crosslinking agent), and zinc chloride And the like. However, even in the case of the above composition, since the curing rate is slow due to the presence of the crosslinking control agent, there is a problem that the polarization degree is deteriorated due to the deterioration of the heat and moisture.

1. Japanese Laid-Open Publication No. 1995-134212

The present invention provides an adhesive composition for a polarizing plate having improved water resistance without lowering adhesive force and polarization degree.

The present invention relates to an adhesive for a polarizing plate, which comprises an acetoacetyl group-modified polyvinyl alcohol-based resin, a crosslinking agent, and a water-soluble chelate compound and does not contain a crosslinking regulator and whose average degree of polymerization of the acetoacetyl-modified polyvinyl alcohol- Lt; / RTI >

In another embodiment, the acetoacetyl group-modified polyvinyl alcohol-based resin may be contained in an amount of 3 to 9% by weight based on the solid content of the adhesive composition.

In another embodiment, the cross-linking agent may be contained in an amount of 20 to 50 parts by weight based on 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol resin, and the water-soluble chelate compound may be included in an amount of 2 to 10 parts by weight.

In another embodiment, the crosslinking agent may be glyoxyl.

In another embodiment, the water-soluble chelate compound may be at least one selected from the group consisting of zinc chloride, cobalt chloride, magnesium chloride, magnesium acetate, aluminum nitrate, nitrate salt, and zinc sulfate.

The present invention also relates to a polarizing plate comprising a polyvinyl alcohol polarizer; An adhesive layer stacked on one surface or both surfaces of the polarizer, the adhesive layer containing the adhesive composition; And a polarizer protective film laminated on one side or both sides of the adhesive layer.

The adhesive composition for a polarizing plate of the present invention has an effect of improving water resistance without lowering the adhesive force and the degree of polarization.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram schematically showing an evaluation test method for water resistance according to an experimental example.

Hereinafter, the present invention will be described in detail.

The present invention relates to an adhesive for a polarizing plate, which comprises an acetoacetyl group-modified polyvinyl alcohol-based resin, a crosslinking agent, and a water-soluble chelate compound and does not contain a crosslinking regulator and whose average degree of polymerization of the acetoacetyl-modified polyvinyl alcohol- And a polarizer wherein the polarizer and the polarizer protective film are bonded to each other using the composition and the adhesive composition.

The adhesive composition of the present invention has an effect of solving the liquid stability problem by improving the adhesive injecting process and having adhesion and durability without adding a crosslinking regulator which causes a decrease in polarization degree due to heat and humidity degradation. That is, the present invention is characterized in that the content of the acetoacetyl group-modified polyvinyl alcohol resin, the crosslinking agent, and the water-soluble chelate compound as the adhesive composition except for the crosslinking regulator is increased to improve the water resistance without lowering the polarization degree.

Hereinafter, the constitution of the adhesive composition will be described in more detail.

Acetoacetyl group  denaturalization Polyvinyl alcohol system  Suzy

The acetoacetyl group-modified polyvinyl alcohol (PVA) based resin contains functional groups having higher reactivity than modified polyvinyl alcohol resins such as carboxyl group denaturation, methylol group denaturation, amino group denaturation and the like, and is excellent in durability.

The acetoacetyl group-modified polyvinyl alcohol-based resin can be obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. Specifically, a method of dispersing a polyvinyl alcohol-based resin in a solvent such as acetic acid and adding diketene thereto, a method of previously dissolving a polyvinyl alcohol-based resin in a solvent such as dimethylformamide or dioxane, Or a method in which a diketene gas or liquid diketene is directly contacted with a polyvinyl alcohol-based resin, or the like. The acetoacetyl group-modified polyvinyl alcohol resin is not particularly limited so long as the acetoacetyl group modification degree is 0.1 mol% or more, preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, and most preferably 2 To 7 mol%. When the degree of modification of the acetoacetyl group is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient, which is unsuitable. When the degree of modification of the acetoacetyl group exceeds 40 mol%, the effect of improving the water resistance may be insignificant.

The degree of saponification of the acetoacetyl group-modified polyvinyl alcohol-based resin is not particularly limited, but is preferably 80 mol% or more, more preferably 85 mol% or more. When the degree of saponification of the polyvinyl alcohol-based resin contained in the adhesive composition is low, the sufficient water-solubility is difficult to manifest, and thus the adhesiveness tends to become insufficient.

The acetoacetyl group-modified polyvinyl alcohol-based resin may have an average degree of polymerization of 1,500 or less. The average degree of polymerization of the acetoacetyl group-modified polyvinyl alcohol-based resin is 1,500 or less.

Examples of the products include Z-100, Z-200, Z-200H, Z-210, Z-220 and Z-320 (Nippon Synthetic Chemical Industry Co., Ltd.).

The acetoacetyl group-modified polyvinyl alcohol-based resin may be contained in an amount of 3 to 9% by weight based on the solid content of the adhesive composition. When the content is less than 3% by weight, the cured product is insufficient and the water resistance is lowered. When the content is more than 9% by weight, the viscosity of the composition is increased and bubbles may be mixed in the bonding process.

Glyoxal Cross-linking agent

The cross-linking agent included in the adhesive composition is an acrylic resin (acetoacetyl) modified polyvinyl alcohol (PVA) resin which is improved in adhesion and water resistance to a protective film such as a polyvinyl alcohol (PVA) polarizer and a cellulose film or an olefin film Play a role in

It is presumed that the function as the glyoxal crosslinking agent is that the aldehyde portion of the glyoxal proceeds with the condensation reaction with the hydroxyl group of the polyvinyl alcohol-based resin.

The glyoxal is in the range of 20 to 50 parts by weight of the glyoxal crosslinking agent relative to 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol-based resin. When the weight ratio of glyoxal is not more than 20, the water resistance of the adhesive layer becomes insufficient when the polarizing plate is used, and when the weight ratio of glyoxal is more than 50 parts by weight, have.

receptivity Chelate  compound

The water-soluble chelate compound contained in the adhesive composition can increase the degree of crosslinking between the adhesive layer and a protective film such as a polyvinyl alcohol (PVA) -based polarizer and a cellulose-based film or an olefin-based film to improve adhesion and water resistance, Can also act as additive without problems.

The water-soluble chelate compound is added to accelerate curing of the glyoxal. Examples of the chelate compound include zinc chloride, cobalt chloride, magnesium chloride, magnesium acetate, aluminum nitrate, zinc nitrate, and zinc sulfate. Particularly, zinc chloride and zinc nitrate, aluminum nitrate, which are excellent in the function of a crosslinking catalyst, are preferable.

The water-soluble chelate compound is in the range of 2 to 10 parts by weight based on 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol-based resin. When the weight ratio of the water-soluble chelate compound to the water-soluble chelate compound is less than 2, the water resistance of the adhesive layer becomes insufficient when the polarizing plate is used. When the weight ratio is more than 10 parts by weight, the optical characteristics are deteriorated.

The viscosity of the adhesive composition at 20 캜 is preferably in the range of 3 to 25 mPa · sec. When the viscosity of the adhesive composition is less than 3 mPa · sec, the water resistance of the polarizing plate can not be sufficiently exhibited. When the viscosity is 25 mPa · sec or more, the optical characteristics of the polarizing plate deteriorate.

The adhesive composition according to the present invention may be prepared by adding a conventionally known suitable additive such as a plasticizer, a silane coupling agent, an antistatic agent, a fine particle, an alcohol for improving spreadability, and a leveling agent to the extent that the effect of the present invention is not impaired .

The form of the adhesive composition is not particularly limited, but it is preferably a liquid form in order to form a uniform adhesive layer on the surface of the polarizer or the protective film as the adhesive. A solution type or a dispersed liquid type of various solvents can be used for such a liquid type adhesive, and a solution type is preferable in view of the coated surface of the substrate, and a solution type or a dispersed liquid type in which water is used as a solvent is suitable from the viewpoint of stability.

Hereinafter, the configuration of the polarizing plate will be described in detail.

Polarizer (Polarizing film)

The polyvinyl alcohol-based resin for forming a polarizer is obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate resin include a copolymer of vinyl acetate and other monomers copolymerizable therewith, as well as polyvinyl acetate, which is a homopolymer of vinyl acetate. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamides having an ammonium group, and the like. The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified, and for example, a polyvinyl polymer modified with an aldehyde or polyvinyl acetal may be used. The average degree of polymerization of the polyvinyl alcohol-based resin constituting the polarizer is usually 1,000 to 10,000, preferably 1,500 to 5,000.

(Polyvinyl alcohol-based resin film) obtained by film-forming such a polyvinyl alcohol-based resin is used for the original film of the polarizer (polarizing film). The method of forming the polyvinyl alcohol-based resin is not particularly limited, and a known film-forming method can be employed. The thickness of the polyvinyl alcohol-based resin film to be a disc is not particularly limited, but is, for example, 10 to 150 탆.

Polarizers (polarizing films) are usually produced by a process of uniaxially stretching a polyvinyl alcohol-based resin film which is such a disc, a process of dyeing a polyvinyl alcohol-based resin film with a dichroic dye and adsorbing the dichroic dye, A step of treating the adsorbed polyvinyl alcohol based resin film with an aqueous solution of boric acid, and a step of washing with water after the treatment with the aqueous solution of boric acid.

Uniaxial stretching may be performed before dyeing, simultaneously with dyeing, or after dyeing. In the case of performing uniaxial stretching after dyeing, uniaxial stretching may be performed before the boric acid treatment, during the boric acid treatment, or after the boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these plural steps. In uniaxial stretching, the original film may be uniaxially stretched between different rolls, or may be uniaxially stretched using a heat roll. Further, it may be dry stretching such as stretching in the atmosphere, or wet stretching in which stretching is performed in a state of being swollen with a solvent. The draw ratio is usually 3 to 8 times.

In order to dye a polyvinyl alcohol-based resin film with a dichroic dye, for example, a polyvinyl alcohol-based resin film can be dipped in an aqueous solution containing a dichroic dye. As the dichroic dye, iodine or a dichroic dye is specifically used. It is preferable that the polyvinyl alcohol-based resin film is subjected to immersion treatment in water before the dyeing treatment.

When iodine is used as the dichroism dye, a method is generally employed in which a polyvinyl alcohol-based resin film is dipped in an aqueous solution containing iodine and potassium iodide and is dyed. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually 20 to 40 占 폚, and the immersion time in this aqueous solution is usually 20 to 1800 seconds.

When a dichroic dye is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is dipped in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^-3 to 1 part by weight, per 100 parts by weight of water. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The dye aqueous solution used for dyeing usually has a temperature of 20 to 80 DEG C, and the immersion time for this aqueous solution is usually 10 to 1,800 seconds.

The boric acid treatment after dyeing with the dichroic dye is carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid. The amount of boric acid in the aqueous solution containing boric acid is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, it is preferable that the aqueous solution containing boric acid contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The immersing time in the boric acid-containing aqueous solution is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

The polyvinyl alcohol-based resin film after treatment with boric acid is usually washed with water. The water washing treatment is carried out, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of the water in the water washing treatment is usually 5 to 40 占 폚, and the immersing time is usually 1 to 120 seconds. After washing with water, drying treatment is carried out to obtain a polarizer (polarizing film). The drying treatment is usually carried out using a hot-air dryer or a far-infrared heater. The temperature of the drying treatment is usually 30 to 100 占 폚, preferably 50 to 80 占 폚. The time for the drying treatment is usually 60 to 600 seconds, preferably 120 to 600 seconds.

In this way, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment to obtain a polarizer (polarizing film). The thickness of the polarizer (polarizing film) is usually in the range of 5 to 40 μm, preferably in the range of 10 to 35 μm.

Protective film

In the polarizing plate of the present invention, a protective film is laminated on at least one surface of a polarizer (polarizing film) with the above-described adhesive layer interposed therebetween. As the protective film, for example, various transparent resin films such as a cellulosic resin film, a cycloolefin resin film, an acrylic resin film, and a polyester resin film can be used.

When a cellulosic resin film is used as the protective film, cellulosic acetate resin in which at least a part of the cellulose is esterified is preferable. And examples thereof include triacetylcellulose, diacetylcerolose, and cellulose acetate acetate propionate.

The cycloolefin-based resin is a thermoplastic resin having a monomer unit of cycloolefin such as norbornene or a polycyclic norbornene-based monomer, and a ring-opening polymer of the cycloolefin or a ring-opened copolymer using two or more cycloolefins But may be an addition copolymer of a cycloolefin and an aromatic compound having a chain olefin or vinyl group. In addition, a polar group may be introduced into the cycloolefin-based resin.

The polarizer (polarizing film) using the adhesive composition can be bonded to the protective film by an appropriate method. For example, the polarizer (polarizing film) can be bonded to the protective film by a flexible method, a Meyer bar coating method, a gravure coating method, a die coating method, an immersion coating method, (Polarizing film) and / or the adhesive surface of the protective film, and superposing the adhesive composition. The flexible method is a method of applying an adhesive composition to a surface of a polarizer (polarizing film) or protective film to be coated, while moving the film in a generally vertical direction, usually in a horizontal direction, or in an inclined direction therebetween.

After the adhesive composition is applied, the polarizer (polarizing film) and the protective film are sandwiched by a nip roll.

Further, surface treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, frame treatment or saponification treatment may be appropriately performed on the surface of the polarizer (polarizing film) and / or the protective film to improve the adhesiveness. As the saponification treatment, a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide can be mentioned.

After the polarizer (polarizing film) and the protective film are laminated, a drying treatment is performed. The drying treatment is carried out, for example, by spraying hot air, but the temperature at that time is appropriately selected in the range of 50 to 100 占 폚. The drying time is usually 30 to 1,000 seconds.

Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples and Experimental Examples. However, the following examples, comparative examples and experimental examples are for illustrating the present invention, and the present invention is not limited by the following examples, comparative examples and experimental examples, and can be variously modified and changed.

Manufacturing example  One. Polarizer  Produce

A polyvinyl alcohol film having a thickness of 75 탆 and an average degree of polymerization of 2,400 and a saponification degree of 99.9 mol% or more was uniaxially stretched by a dry method about 5 times and immersed in water (distilled water) at 60 캜 for 1 minute while maintaining the stretched state And immersed for 60 seconds in an aqueous solution at 28 DEG C in which the weight ratio of after-iodine / potassium iodide / distilled water was 0.05 / 5/100. Thereafter, the substrate was immersed in an aqueous 72 ° C aqueous solution having a weight ratio of potassium iodide / boric acid / distilled water of 8.5 / 8.5 / 100 for 300 seconds, washed with distilled water at 26 ° C for 20 seconds and dried at 65 ° C to remove iodine Adsorbed polarizers were prepared.

Manufacturing example  2. Preparation of protective film

A triacetyl cellulose-based film, KC8UX (Konica Corp., T), was used by saponification

Example  One

(1) Preparation of adhesive composition

Acetoacetyl group denatured polyvinyl alcohol resin (Z200, Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization 1200) having a degree of saponification of 99.2 mol% was dissolved in water (distilled water) to prepare a 6 wt% acetoacetyl group The modified polyvinyl alcohol was added.

The aqueous solution of the acetoacetyl group-modified polyvinyl alcohol resin and glyoxal (40% aqueous solution, purified water) to be a crosslinking agent were mixed so as to be 20 parts by weight per 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol resin, Chelate compound Zinc chloride (purified gold) was mixed in an amount of 2 parts by weight based on 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol resin to prepare an adhesive composition.

(2) Bonding of polarizer to protective film (Polarizing plate production)

The adhesive composition was coated on both sides of the polarizer prepared in Preparation Example 1 to a dry film thickness of 0.1 mu m, and then a cellulose protective film (Konica Corp., KC8UX (trade name), triacetyl cellulose film) Respectively. The bonded polarizing plate was dried in a hot air drier at 80 캜 for 5 minutes to prepare a polarizing plate.

Example  2 to 9 and Comparative Example  1 to 7

An adhesive composition was prepared in the same manner as in Example 1 except that the ratio was changed (unit: parts by weight, see Table 1).

Example  10

Adhesive composition An adhesive composition was prepared under the same conditions as in Example 1 except that acetoacetyl group-modified polyvinyl alcohol was contained in an amount of 3% by weight based on the solid weight (see Table 1).

Example  11

Adhesive composition An adhesive composition was prepared under the same conditions as in Example 1 except that acetoacetyl group-modified polyvinyl alcohol was contained in an amount of 9 wt% based on the solids weight (see Table 1).

Example  12

Adhesive composition An adhesive composition was prepared under the same conditions as in Example 1 except that acetoacetyl-modified polyvinyl alcohol was contained in an amount of 2% by weight based on the solid weight (see Table 1).

Example  13

Adhesive composition An adhesive composition was prepared under the same conditions as in Example 1 except that acetoacetyl-modified polyvinyl alcohol was contained in an amount of 10% by weight based on the solid weight (see Table 1).

Example  14

An adhesive composition was prepared under the same conditions as in Example 1 except that the acetoacetyl group-modified polyvinyl alcohol resin in the adhesive composition was changed from Z200 to Z100 (Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization: 650).

Comparative Example  8

An adhesive composition was prepared under the same conditions as in Example 1 except that the crosslinking agent in the adhesive composition was changed from glyoxal to sodium glyoxal (Sigma Aldrich) (see Table 1).

division Acetoacetyl group-modified polyvinyl alcohol (Z200) Polyvinyl alcohol resin (PVA-117H, Kuraray) Glyoxal Water-soluble chelate compound Amount of blending Kinds Example 1 100 - 20 2 Zinc chloride Example 2 100 - 20 5 Zinc chloride Example 3 100 - 20 10 Zinc chloride Example 4 100 - 30 5 Zinc chloride Example 5 100 - 40 5 Zinc chloride Example 6 100 - 50 5 Zinc chloride Example 7 100 - 20 5 Zinc nitrate (antiseptic) Example 8 100 - 20 5 Aluminum nitrate (Aldrich) Example 9 100 - 20 5 Magnesium acetate (purified water) Example 10 100 - 20 2 Zinc chloride Example 11 100 - 20 2 Zinc chloride Example 12 100 - 20 2 Zinc chloride Example 13 100 - 20 2 Zinc chloride Example 14 100 (Z100) - 20 2 Zinc chloride Comparative Example 1 - 100 20 2 Zinc chloride Comparative Example 2 100 100 20 5 Zinc chloride Comparative Example 3 50 50 20 5 Zinc chloride Comparative Example 4 100 100 10 5 Zinc chloride Comparative Example 5 100 100 60 5 Zinc chloride Comparative Example 6 100 100 20 One Zinc chloride Comparative Example 7 100 100 20 15 Zinc chloride Comparative Example 8 100 - 20
(Glyoxane
salt) 2 Zinc chloride

* Claressa PVA-117H Polymerization degree 1700

Experimental Example

(1) Adhesion (Cutter Evaluation)

The prepared polarizing plate was allowed to stand at room temperature for 1 hour, and a cutter blade was inserted between each polarizing plate (between the polarizing plate and the polarizer protective film), and the way when the blade was pushed was evaluated according to the following criteria , And the results are shown in Table 2 below.

A: The cutter blade does not enter any film.

○: When pushing the blade, it stops when the blade reaches 1 to 2 mm between at least one of the films.

?: When the blade is pushed, it stops when the blade enters 3 to 5 mm between at least one of the films.

X: When pushing the blade, the blade is easily inserted between at least one of the films.

(2) Water resistance

Each of the polarizing plates left for 24 hours in an environment of 23 DEG C and relative humidity of 55% was subjected to the following water temperature resistance test to evaluate the water resistance. The polarizing plate was cut into strips of 5 cm x 2 cm with the absorption axis of the polarizing plate as a long side to make a sample, and the dimension in the long side direction thereof was measured accurately. Here, the sample exhibits uniform color uniformly over the entire surface due to the iodine adsorbed on the polarizer (polarizing film). Fig. 1 is a diagram schematically showing an evaluation test method for water resistance. Fig. 1 (A) shows samples 1 before immersion in hot water, and Fig. 1 (B) shows sample 1 after immersion in hot water. As shown in Fig. 1 (A), one short side of the sample was held by the waveguide 5, about 80% in the longitudinal direction was immersed in a 60 degree water bath, and held for 4 hours. Thereafter, the sample (1) was taken out of the water tank and wiped off the water.

The polarizer (polarizing film) 4 of the polarizing plate shrinks due to immersion in hot water. The degree of shrinkage of the polarizer (polarizing film) 4 is set so that the distance from the end 1a of the short side of the sample 1 (the end of the protective film) to the end of the polarizer (polarizing film) And the shrinkage length was determined. As shown in Fig. 1 (B), the polarizer (polarizing film) 4 located at the center of the polarizing plate is shrunk by immersion in hot water so that the polarizing film (polarizing film) Iodine is eluted and a portion (3) in which a color is missing is formed in the periphery of the sample (1). The degree of discoloration was evaluated by measuring the distance from the end of the shrunk polarizer (polarizing film) 4 at the center of the short side of the sample 1 to the area where the peculiar color of the polarizing plate remained, . The sum of the shrinkage length and the length without iodine was defined as the total erosion length x. The total erosion length x is the distance from the end 1a of the sample 1 to the region where the color unique to the polarizer remains, at the center of the short side of the sample 1. The shorter the shrinkage length, the length without iodine, and the total erosion length x, the greater the adhesion in the presence of water. The total erosion length x was evaluated according to the following four steps, and the results are shown in Table 2.

◎: total erosion length x less than 2 mm

○: Total erosion length × 2 mm or more and less than 3 mm

△: total erosion length × 3 mm or more and less than 5 mm

×: total erosion length × 5 mm or more

(3) Transmittance, polarization degree (%)

The prepared polarizer was cut into a size of 4 cm x 4 cm to prepare a specimen. The specimen was attached to a measurement holder and then measured using an ultraviolet ray spectrophotometer (V-7100, manufactured by JASCO) Respectively.

division Adhesion Water resistance Unit transmittance Polarization degree Example 1 ◎ ◎ 43.2 99.996 Example 2 ◎ ◎ 43.1 99.997 Example 3 ◎ ◎ 43.3 99.996 Example 4 ◎ ◎ 43.2 99.996 Example 5 ◎ ◎ 43.2 99.996 Example 6 ◎ ◎ 43.3 99.996 Example 7 ◎ ◎ 43.2 99.995 Example 8 ◎ ◎ 43.4 99.996 Example 9 ◎ ○ 43.2 99.996 Example 10 ◎ ◎ 43.3 99.995 Example 11 ◎ ◎ 43.2 99.995 Example 12 ◎ ○ 43.1 99.995 Example 13 ◎ ◎ 43.2 99.993 Example 14 ◎ ◎ 43.2 99.997 Comparative Example 1 ◎ △ 43.2 99.991 Comparative Example 2 ◎ ○ 43.2 99.988 Comparative Example 3 ◎ ○ 43.2 99.989 Comparative Example 4 ◎ △ 43.2 99.990 Comparative Example 5 Glycogenesis Comparative Example 6 ◎ △ 43.2 99.992 Comparative Example 7 ◎ ○ 43.2 99.988 Comparative Example 8 ○ △ 43.2 99.984

As shown in Table 2, Examples 1 to 14 exhibited excellent adhesiveness, water resistance and optical properties as compared with Comparative Examples 1 to 8.

Claims (5)

An acetoacetyl group-modified polyvinyl alcohol-based resin, a crosslinking agent, and a water-soluble chelate compound,
Does not include a cross-linking agent,
Wherein the acetoacetyl group-modified polyvinyl alcohol-based resin has an average degree of polymerization of 1,500 or less. The adhesive composition for a polarizing plate according to claim 1, wherein the acetoacetyl group-modified polyvinyl alcohol resin is contained in an amount of 3 to 9% by weight based on the solid content of the adhesive composition. [3] The method according to claim 1, wherein, based on 100 parts by weight of the acetoacetyl group-modified polyvinyl alcohol-based resin,
The crosslinking agent is contained in an amount of 20 to 50 parts by weight,
Wherein the water-soluble chelate compound is contained in an amount of 2 to 10 parts by weight. The adhesive composition for a polarizing plate according to claim 1, wherein the water-soluble chelate compound is at least one selected from the group consisting of zinc chloride, cobalt chloride, magnesium chloride, magnesium acetate, aluminum nitrate, zinc nitrate, and zinc sulfate. Polyvinyl alcohol polarizers;
An adhesive layer which is laminated on one surface or both surfaces of the polarizer and contains the adhesive composition according to any one of claims 1 to 4; And
And a polarizer protective film laminated on one side or both sides of the adhesive layer.

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