KR20110060509A - Method for producing polarizing plate - Google Patents

Abstract

PURPOSE: A method for polarizer is provided to reduce the speed difference of bonding processes with respect to the polarizer and two kinds of protecting films by reducing the speed of a bonding process with respect to the polarizer and a protecting film with the high moisture permeability. CONSTITUTION: One protecting film is bonded with one surface of a polarizer. The moisture permeability of one protecting film is less than or equal to 300g/m^2·day at 40 degrees Celsius and 90%RH. Another protecting film is bonded with another surface of the polarizer. The moisture permeability of another protecting film is more than 300g/m^2·day at 40 degrees Celsius and 90%RH. A water-based adhesive containing alcohol bonds the polarizer and another protecting film.

Description

Manufacturing method of polarizing plate {METHOD FOR PRODUCING POLARIZING PLATE}

The present invention relates to a method of manufacturing a polarizing plate capable of suppressing curl generation of a polarizing plate by effectively bonding protective films having different moisture permeability to a polarizer.

The polarizing plate is widely used as a supply element of polarization and a detection element of polarization in a liquid crystal display device.

In general, a polarizing plate is a cellulose acetate type represented by a transparent protective film such as triacetylcellulose (TAC) through an adhesive on both sides of a polarizer made of polyvinylalcohol (PVA) -based resin in which a dichroic dye is adsorbed. The protective film has a laminated structure.

Recently, in order to express unusual optical properties, there has been an increasing number of polarizing plates on which protective films having different physical properties and the like are disposed on both surfaces of the polarizer. However, when different types of protective films are disposed on both sides of the polarizer, both sides of the polarizer are asymmetrical, so there is a problem of curling in the polarizer. In particular, when the protective film having different moisture permeability is disposed on both sides of the polarizer, a worse curl occurs.

Since the polarizing plate is required to be handled with the improvement of the function of LCD, the improvement of luminance, and the enlargement of size, it is preferable to suppress curl. In addition, the curled polarizing plate has a problem that bubbles are mixed when adhering to the liquid crystal cell.

In order to suppress the occurrence of curling, Korean Laid-Open Patent Publication No. 2007-96826 (published Oct. 2, 2007) is a cycloolefin resin film laminated on one side of the polarizer with an adhesive, and then a cellulose acetate film is laminated on the other side. The polarizing plate manufacturing method in which the moisture content before a cellulose acetate type film is laminated | stacked is adjusted to 0.5% or more is disclosed. This polarizing plate can suppress curl, but the moisture content of the polarizer and the cycloolefin resin film laminated state should be 0.5%, so the moisture content of the film must be maintained at a certain level or more, and the process is complicated. In addition, there is a problem that takes a long time to manufacture a polarizing plate.

Therefore, the development of a polarizing plate capable of suppressing curl by improving the adhesion speed between the protective film and the polarizer having different moisture permeability is required.

It is an object of the present invention to provide a method for efficiently manufacturing a polarizing plate by reducing the difference in adhesion speed between protective films having different moisture permeability.

Another object of the present invention is to provide a method for producing a polarizing plate capable of suppressing curl generation of the polarizing plate.

1. On one side of the polarizer, a protective film with a moisture permeability of 300 g / m2 · day or less at 40 ° C. and 90% RH; on the other hand, a protective film with a moisture permeability of more than 300 g / m 2 · day at 40 ° C. and 90% RH. In bonding the polarizer to produce a polarizing plate, a method of manufacturing a polarizing plate comprising bonding a polarizer and a protective film having a water vapor transmission rate of more than 300 g / m 2 · day at 40 ° C. and 90% RH with an aqueous adhesive containing alcohol.

2. The method according to the above 1, wherein the alcohol-containing water-based adhesive comprises a solvent in which the weight ratio of water and alcohol is 99: 1 to 45:55.

3. In the above 1, the protective film having a water vapor transmission rate of less than 300g / ㎡ · day at 40 ℃ and 90% RH is a group consisting of acrylic resin, polyester resin, polyimide resin, norbornene resin and polyolefin resin Method for producing a polarizing plate is selected from.

4. In the above 1, the protective film of the moisture permeability of more than 300g / ㎡ · day at 40 ℃ and 90% RH is made of a triacetyl cellulose-based resin manufacturing method.

5. The method according to the above 1 or 2, wherein the alcohol-based water-based adhesive containing 1 to 100 parts by weight of the crosslinking agent based on 100 parts by weight (based on the solid content) of the polyvinyl alcohol-based resin.

6. In the above 1 or 2, the polarizer and the protective film having a water vapor transmission rate of less than 300g / ㎡ · day at 40 ℃ and 90% RH is a polarizing plate that is bonded with an aqueous adhesive containing water, polyvinyl alcohol-based resin and a crosslinking agent. Manufacturing method.

7. In the above 3, the protective film having a water vapor transmission rate of less than 300g / ㎡ · day at 40 ℃ and 90% RH is a manufacturing method of a polarizing plate made of norbornene-based resin.

According to the method of manufacturing a polarizing plate of the present invention, the adhesive speed between the protective film and the polarizer having high moisture permeability is lowered by using an adhesive containing an alcohol solvent, thereby reducing the difference between the adhesion rate of the protective film and the polarizer having low moisture permeability. ) It is effective to suppress the occurrence.

Since the polarizing plate manufacturing method of the present invention uses an adhesive having a weight ratio of water and an alcohol solvent of 99: 1 to 45:55, the adhesion between the polarizer and the protective film is excellent.

The polarizing plate manufacturing method of the present invention can solve the problem that bubbles are mixed when bonding to the liquid crystal cell by suppressing curl generation, thereby greatly improving the processability.

The polarizing plate manufacturing method of the present invention is advantageous in producing a thinner and larger polarizing plate by suppressing curl generation.

In the present invention, in bonding two kinds of protective films having different moisture permeability to the polarizer with an aqueous adhesive, an aqueous adhesive containing an alcohol solvent is used between the protective film having high moisture permeability and the polarizer, and the protective film having high moisture permeability between the polarizer and the polarizer. It is possible to reduce the adhesion speed difference between the polarizer and the two types of protective film by reducing the adhesion rate, and thus relates to a method of manufacturing a polarizing plate capable of suppressing curl generation of the polarizing plate.

Hereinafter, the present invention will be described in more detail.

The polarizer is a dichroic dye adsorbed on the stretched polyvinyl alcohol-based film. The polyvinyl alcohol-based resin constituting the polarizer can be produced by saponifying a polyvinyl acetate-based resin. As an example of polyvinyl acetate type resin, the copolymer etc. with vinyl acetate and the other monomer copolymerizable with this besides the polyvinyl acetate which is a homopolymer of vinyl acetate are mentioned. Specific examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamides having an ammonium group, and the like. In addition, the polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of saponification of the polyvinyl alcohol-based resin may be 85 to 100 mol%, preferably 98 mol% or more. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

The manufacturing method of the present invention relates to bonding protective films having different moisture permeability to two polarizers having different components.

The protective film is a generic term for a film for protecting it because the polarizer is mechanically weak, and when the retardation film performs the role of the polarizer protective film, the retardation film is also regarded as belonging to the protective film of the present invention.

The protective film may have a moisture permeability different according to the type of resin, and a film having excellent transparency, mechanical strength, thermal stability, moisture shielding, and isotropy may be used.

In the present invention, a protective film having high moisture permeability is bonded to one side of the polarizer, and a protective film having low moisture permeability is bonded to the other side.

A protective film having a high moisture permeability includes, for example, a case where the moisture permeability at 40 ° C. and 90% RH is more than 300 g / m 2 · day. For example, a film made of a cellulose resin such as diacetyl cellulose or triacetyl cellulose may be used. Can be.

In addition, the protective film having a low moisture permeability includes, for example, a case where the water vapor transmission rate at 40 ° C. and 90% RH is 300 g / m 2 · day or less, such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene terephthalate-iso Polyester-based resins such as phthalate copolymers; A resin prepared by the condensation reaction of an aromatic diamine with an aromatic diamine such as pyromellitic dianhydride with diaminodiphenyl ether and an aromatic carboxylic anhydride, an imide ring closure reaction, and an aromatic diamine obtained with maleic anhydride and diaminodiphenylmethane. Polyimide resins such as polyimide; A resin obtained by introducing a (co) polymer of a ring-open norbornene monomer into a polar group such as maleic acid, cyclopentadiene, and the like after modification, and a resin obtained by addition polymerization of norbornene monomer, norbornene monomer and ethylene, resins obtained by addition polymerization of olefin monomers such as α-olefins, nordenene monomers and resins obtained by addition polymerization of cyclic olefin monomers such as cyclopentene, cyclooctene or 5,6-dihydrodicyclopentadiene Bonenic resins; And films selected from the group consisting of polyolefin-based resins such as polyethylene, polypropylene, ethylene-propylene copolymers, homopolymers or copolymers of α-olefins such as poly-4-methylpentene-1 having 1 to 6 carbon atoms. .

The protective film may contain appropriate one or more additives. Specific examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, colorants, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like.

The protective film may be subjected to a known surface treatment such as saponification treatment, corona treatment, plasma treatment, and adhesion layer treatment in order to facilitate adhesion with the polarizer.

In the present invention, the polarizer and the protective films having different moisture permeability are bonded to each other with an aqueous adhesive. It is preferable that the basics of this aqueous adhesive are polyvinyl alcohol-type resin, a crosslinking agent, and water. For example, as shown in FIG. 1, the polarizer and the high moisture permeability protective film are bonded with an aqueous adhesive containing an alcohol solvent, and the low water vapor permeability protective film is bonded with an aqueous adhesive of a basic composition that does not contain an alcohol solvent.

Polyvinyl alcohol-based resin, which is one of the components of the aqueous adhesive, is a vinyl polymer resin and is excellent in adhesion with a polyvinyl alcohol-based polarizer. In order to improve the durability of the polarizing plate, a polyvinyl alcohol resin containing acetoacetyl group is preferable, and a carboxyl group-modified polyvinyl alcohol resin containing a highly reactive functional group is preferable in order to improve the adhesiveness and moisture-heat resistance of the adhesive composition.

The degree of polymerization and the degree of saponification of the polyvinyl alcohol-based resin are not particularly limited. It is preferable that the average degree of polymerization is 100 to 3,000 and the average degree of saponification is 85 to 100 mol% in consideration of adhesion.

The crosslinking agent may be a conventional crosslinking agent to improve the water resistance and durability of the adhesive. Specific examples of the crosslinking agent include aldehyde compounds such as formaldehyde, glyoxal, and glutaraldehyde as organic crosslinking agents; Amino group-containing compounds such as urea resin, guanamine resin, aniline aldehyde resin, melamine resin, and methylolmelamine resin; Glycidyl group-containing compounds such as water-soluble epoxy resins and polyaminopolyamide-epichlorohydrin; Amine compounds such as ethylenediamine, hexamethylenediamino, methaxylenediamine, 1,3-bisaminocyclohexane, polyoxyalkylenediamine and polyamine; Hydrazide compounds such as adipic acid hydrazide, carbohydrazide, and polyacrylic acid hydrazide; Isocyanate compounds, such as polyisocyanate and block isocyanate; Hydrazine compounds; Boron compounds such as boric acid and borax as acid anhydrides and inorganic crosslinking agents; Zirconium compounds, such as chlorohydroxyoxo zirconium, zirconyl nitrate, and zircosol; Titanium compounds such as tetraalkoxy titanate and water-soluble titanium compounds; Aluminum compounds such as aluminum sulfate, aluminum chloride and aluminum nitrate; Phosphoric acid compounds such as phosphite ester and bisphenol A-modified polyphosphoric acid; And a silicon compound having a reactive functional group such as an alkoxy group or glycidyl group.

Since the alcohol solvent is usually removed in a drying step, it is a boiling point lower than water, such as 100 ° C. or lower, preferably 80 ° C. or lower, more preferably 70 ° C. or lower, and the alcohol solvent can be mixed with water and used. Specific examples of the alcohol solvent include alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, isopropanol, 1-butanol and 2-butanol.

The water-based adhesive composition for bonding the polarizer and the protective film having high moisture permeability is 1 to 10 parts by weight of polyvinyl alcohol-based resin and polyvinyl alcohol-based resin (based on solids content) 100 parts by weight of mixed solvent (water and alcohol solvent mixture) 100 parts by weight. 1 to 100 parts by weight of the crosslinking agent, based on parts by weight. At this time, the water and the alcohol solvent excluding the solid content is mixed in a weight ratio of 99: 1 to 45:55, preferably 95: 5 to 50:50, more preferably 90:10 to 80:20. When the mixing ratio of the alcohol is less than 1, it is not effective for controlling the adhesion rate, and when the mixing ratio of the alcohol exceeds 55, the adhesive force is not good due to the poor solubility of the resin or the decrease in the viscosity stability of the adhesive composition.

In addition, the water-based adhesive composition for bonding the polarizer and the protective film with low moisture permeability has 1 to 10 parts by weight of polyvinyl alcohol-based resin and 100 parts by weight of polyvinyl alcohol-based resin (based on solids content) based on 100 parts by weight of water. It contains 100 parts by weight.

When the content of the crosslinking agent is less than 1 part by weight based on 100 parts by weight of the polyvinyl alcohol-based resin, the heat and moisture resistance may be weak, and when the content of the crosslinking agent is greater than 100 parts by weight, the adhesive strength may be lowered.

Conventionally, one side is provided with a high moisture-permeable protective film, the other side is provided with a low-moisture-permeable protective film, the polarizer is first bonded with a high moisture-permeable protective film during the drying process, the low moisture-permeability that was dried at the same speed Since the protective film is not bonded, shrinkage stress is generated in the direction of the film with high moisture permeability, resulting in a large curl.

In order to improve this, the present invention bonds a polarizer and a protective film having high moisture permeability into an aqueous adhesive containing an alcohol solvent. Since the protective film having high moisture permeability has a high adhesion speed (drying speed) with the polarizer, an aqueous adhesive containing an alcohol solvent is applied between the protective film having high moisture permeability and the polarizer to slow down the adhesion speed. Therefore, the moisture permeability is low and the adhesion rate of the protective film and the polarizer is slow to reduce the shrinkage stress is suppressed to suppress the occurrence of curl. The alcohol solvent is expected to be one factor that can hinder the moisture permeation through the protective film in order to slow the adhesion rate.

The adhesive for bonding the polarizer and the protective film is applied to either side of the polarizer and the protective film or both. The coating operation is not particularly limited, and various methods such as a roll method, a spray method, and a dipping method can be used. It is preferable to apply | coat the adhesive bond layer so that the thickness of the adhesive bond layer formed after drying in consideration of solid content may be 10-5,000 nm, Preferably it is 30-600 nm. When the thickness is less than 10 nm, the adhesion may be poor, and when the thickness is greater than 5,000 nm, uniform application of the adhesive may be difficult or thickness irregularity may occur, resulting in poor appearance. In addition, when the polarizer and the protective film is bonded, the tension may be applied to the protective film, but the tension is preferably as low as possible to apply a deformation to the protective film.

After applying the adhesive, the polarizer and the protective film are bonded by a roll laminator or the like. After bonding the polarizer and the protective film, a drying process is performed to form an adhesive layer comprising a coating dry layer.

The polarizing plate to which the polarizer and the protective film are bonded is subjected to a drying process. An example of the drying process is hot air drying in which the drying temperature is 40 to 100 ° C., preferably 60 to 100 ° C. using hot air. The drying time is 20 to 1200 seconds, but it is preferable that the drying time is as short as possible in order to improve productivity. After hot air drying, curing at room temperature or higher than room temperature, for example, 20 to 50 ° C. for 12 to 600 hours is preferable.

In the polarizing plate of the present invention, a surface coating layer such as a hard coating layer, an antireflection layer, an antifouling layer, a diffusion layer, and an antiglare layer may be further laminated on the other side of the protective film not bonded with the polarizer. In addition, the optical functional film may be further laminated by the pressure-sensitive adhesive layer.

The hard coating layer is performed to prevent damage to the surface of the polarizing plate, for example, a cured coating film having excellent hardness, sliding properties, etc. formed by a system for adding a suitable ultraviolet curable resin such as a silicone resin to the surface of the protective film. have. In addition, the antireflection layer is performed for the purpose of preventing external light from being reflected from the surface of the polarizing plate. The antireflective layer can be achieved by forming an antireflective film according to the prior art. In addition, the anti-stick layer is performed for the purpose of preventing the protective film from being in close contact with the adjacent layer. The anti-glare layer is performed to prevent visual perception of the light passing through the polarizer from being inhibited by external light reflected from the surface of the polarizing plate, for example, a roughening system or a transparent particle mixing system using sand blasting, embossing, or the like. Etc., the micro-corrugated structure can be imparted to the surface of the protective film. Transparent particles have an average particle size of 0.5 to 20㎛, specific examples include particles made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide and the like. In addition, the transparent particles may use inorganic fine particles having conductivity or organic fine particles made of a crosslinked or uncrosslinked granular polymer or the like. The transparent particles are 2 to 70 parts by weight, preferably 5 to 50 parts by weight with respect to 100 parts by weight of the resin. The anti-glare layer containing the transparent fine particles may be provided as the protective film itself or as a coating layer applied to the surface of the protective film. The anti-glare layer can also function as a diffusion layer (viewing angle compensation function, etc.) that expands the viewing angle by diffusing light transmitted through the polarizing plate.

The polarizing plate manufactured by the manufacturing method of the present invention can be used in a liquid crystal display device. The liquid crystal display device may be manufactured by peeling a release film of a pressure-sensitive adhesive polarizing plate and then attaching an adhesive layer to a liquid crystal panel.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is obvious that the examples are not intended to limit the scope of the present invention but only to show an example belonging to the present invention. It is natural that modifications and variations of the embodiments fall within the scope of the present invention without departing from the basic technical spirit of the present invention.

[Example]

Preparation Example 1 Preparation of Polarizer

After uniaxially stretching a polyvinyl alcohol (PVA) film having a degree of polymerization of 2,400 and having a saponification degree of 99.9 mol% or more by about 5 times dry, immersed in distilled water at 60 ° C. for 1 minute while maintaining a tension state. It was immersed for 60 seconds in the aqueous solution of 28 degreeC whose weight ratio of iodine / potassium iodide / distilled water is 0.05 / 5/100. After immersion for 300 seconds in a 72 ℃ aqueous solution having a weight ratio of potassium iodide / boric acid / distilled water for 8.5 / 8.5 / 100, washed for 20 seconds with distilled water at 26 ℃ and dried at 65 ℃ to adsorb the iodine to the PVA-based film An oriented polarizer was prepared.

Preparation Example 2 Adhesive Composition Containing No Alcohol Solvent

An adhesive composition was prepared by adding 5 parts by weight of acetoacetylene-modified polyvinyl alcohol resin (Z200, Nippon Synthetic Chemical Co., Ltd.) and 0.5 parts by weight of glyoxal crosslinking agent to 100 parts by weight of distilled water.

Preparation Example 3 Adhesive Composition Containing Alcohol Solvent

Distilled water and ethanol are mixed at a weight ratio of 95: 5, and 5 parts by weight of acetoacetylene-modified polyvinyl alcohol resin (Z200, Nippon Synthetic Chemical Co., Ltd.) and 0.5 parts by weight of glyoxal crosslinking agent are added to 100 parts by weight of the mixed solvent of distilled water and ethanol. An adhesive composition was prepared.

Preparation Example 4 Adhesive Composition Containing Alcohol Solvent

Distilled water and ethanol were prepared in the same manner as in Preparation Example 3 except for mixing in a weight ratio of 50:50.

Preparation Example 5 Adhesive Composition Containing Alcohol Solvent

Distilled water and ethanol were prepared in the same manner as in Preparation Example 3 except that the weight ratio of 40:60.

Preparation Example 6 Pretreatment of Protective Film

(1) Production of norbornene-based films (first protective film)

One side of the norbornene-based film (manufactured by Japan Zeon, trade name "ZEONOR", 40 µm) was subjected to corona treatment with a discharge amount of 200 w · min / m 2, and the moisture permeability was 250 g / m 2 · day.

(2) Preparation of triacetyl cellulose film (second protective film)

A triacetyl cellulose film having a water permeability of 900 g / m 2 · day subjected to a saponification treatment having a thickness of 80 μm was used.

Example 1

After spraying the adhesive prepared in Preparation Example 2 between the PVA-based polarizer prepared in Preparation Example 1 and the protective film of Preparation Example 6-1 so as to have a thickness of 500 nm after drying, the other side of the polarizer was prepared The adhesive prepared in Preparation Example 3 was spray-coated to a thickness of 500 nm after drying between the protective films of Example 6-2, and then bonded using a nip roll. The bonded polarizing plate was dried in a 60 ° C. hot air dryer for 5 minutes to prepare a polarizing plate.

Example 2

A polarizing plate was manufactured in the same manner as in Example 1 except that the adhesive prepared in Preparation Example 4 was used between the other side of the polarizer and the protective film of Preparation Example 6-2.

Example 3

A polarizing plate was manufactured in the same manner as in Example 1 except that the adhesive prepared in Preparation Example 5 was used between the other side of the polarizer and the protective film of Preparation Example 6-2.

Comparative Example 1

A polarizing plate was prepared in the same manner as in Example 1 except that the adhesive prepared in Preparation Example 2 was used between the other side of the polarizer and the protective film of Preparation Example 6-2.

Test Example

1. Curl amount of polarizer

Place the concave side of the curled sample on a reference plane, such as a plane on the table, facing upwards, and adjust the humidity for 48 hours at 25 ° C., 65% RH. The sample was cut | disconnected so that the rectangular sample of 305 mm of long sides and 254 mm of short sides may be made into the angle of 45 degrees with respect to the film forming direction of each side polarizing film.

The angles of both ends of the diagonal line forming the angle close to the film-forming direction of the polarizing film among the two diagonal lines of the humidity-controlled sample were measured by the curled height from the reference plane and averaged to measure the curl amount of the polarizing plate.

The practically acceptable curl amount of a polarizing plate is 20 mm or less, Preferably it is 15 mm or less, More preferably, it is 10 mm or less.

2. Adhesive

The degree of peeling and the degree of damage were observed while peeling between the polarizer and the first protective film, the polarizer and the second protective film of the polarizing plate by hand, and evaluated according to the following criteria. At this time, the polarizer and the protective film do not peel off each other, the better the adhesive strength.

(Circle): It is broken without peeling.

(Triangle | delta): The area which peels is large and a part is damaged.

X: Mostly peeled off.

3. Measuring adhesion time (drying time)

Samples were taken after the bonded sample was put in a hot air oven. The peeling time did not occur at the time of observing the degree of peeling and the degree of damage while peeling between the polarizer and the first protective film, the polarizer and the second protective film of the polarizing plate by hand, and when the substrate was broken, the drying time of the sample was recorded as the adhesion time. .

division Adhesion time (seconds) Curl amount (mm) Adhesive evaluation Protective film 1 Protective film 2 Example 1 370 170 16.5 ○ Curl relief Example 2 400 250 13.5 ○ Curl relief Example 3 410 250 14.0 △ Curl relief Comparative Example 1 380 30 65.0 ○ Deteriorate curl

As shown in the above table, according to the present invention, the polarizers of Examples 1 to 3, in which the polarizer and the high moisture permeability protective film were bonded together with the adhesive containing the alcohol solvent, were curled in comparison with the polarizer of Comparative Example 1. In addition, it was confirmed that the alcohol-containing aqueous adhesive can effectively maintain the adhesive force when the weight ratio of water and alcohol is 99: 1 to 45:55.

Since the polarizing plate of the present invention reduces the difference in the adhesion speed between the polarizer and the first and second protective films, it is expected that the production yield will be improved and the processability will be remarkably increased when the polarizing plate is used in the manufacturing process of the polarizing plate and the liquid crystal display. do.

As described above, the present invention can be applied to the manufacturing process of various image display devices such as liquid crystal display devices in which a polarizing plate without curling is required.

1 is a vertical cross-sectional view of a polarizing plate manufactured according to the present invention.

Claims (7)

On one side of the polarizer, a protective film having a moisture permeability of 300 g / m 2 · day or less at 40 ° C. and 90% RH is bonded. In the manufacturing of a polarizing plate, a method of manufacturing a polarizing plate comprising bonding a polarizer and a protective film having a water vapor transmission rate of more than 300 g / m 2 · day at 40 ° C. and 90% RH with an aqueous adhesive containing alcohol. The method of claim 1, wherein the alcohol-containing aqueous adhesive includes a solvent having a weight ratio of water to alcohol of 99: 1 to 45:55. The protective film according to claim 1, wherein the protective film having a moisture permeability of 300 g / m 2 · day or less at 40 ° C. and 90% RH is selected from the group consisting of acrylic resin, polyester resin, polyimide resin, norbornene resin, and polyolefin resin. Method for producing a polarizing plate. The method of manufacturing a polarizing plate according to claim 1, wherein the protective film having a moisture permeability of more than 300 g / m 2 · day at 40 ° C. and 90% RH is made of a triacetyl cellulose resin. The method of claim 1 or 2, wherein the alcohol-containing aqueous adhesive includes 1 to 100 parts by weight of the crosslinking agent based on 100 parts by weight of the polyvinyl alcohol-based resin (based on the solid content). The polarizing plate according to claim 1 or 2, wherein the polarizer and the protective film having a moisture permeability of 300 g / m 2 · day or less at 40 ° C. and 90% RH are bonded with an aqueous adhesive containing water, a polyvinyl alcohol-based resin, and a crosslinking agent. Way. The method of manufacturing a polarizing plate according to claim 3, wherein the protective film having a moisture permeability of 300 g / m 2 · day or less at 40 ° C. and 90% RH is made of a norbornene-based resin.

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