KR20110056936A - Method for polarizing plates - Google Patents

Abstract

PURPOSE: A method for polarizing plates is provided to prevent the curl of a polarizer by reducing the adhesion speed difference between a protecting film having high water vapor permeability and a protecting film having low water vapor permeability. CONSTITUTION: In a method for polarizing plates, two kinds of protecting film having different water vapor permeability are bonded with each other by a water based adhesive. The moisture ratio of the polarizer is between 5 weight% and 8 weight%. The protecting film is a cellulose based resin.

Description

Manufacturing Method of Polarizing Plate {METHOD FOR POLARIZING PLATES}

The present invention relates to a method of manufacturing a polarizing plate capable of effectively preventing the curling of the polarizing plate as well as increasing the productivity of the polarizing plate by effectively bonding the protective films having different moisture permeability to the 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 and oriented. 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, if a different kind of protective film is 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, 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 included when adhering to the liquid crystal cell.

In consideration of this point, Korean Laid-Open Patent Publication No. 2007-96826 (published on October 2, 2007), wherein a cycloolefin-based resin film is laminated on one side of the polarizer with an adhesive, and then a cellulose acetate-based film is laminated on the other side, acetic acid The polarizing plate manufacturing method which adjusts the moisture content before a cellulose film is laminated | stacked to 0.5% or more is disclosed. Although the polarizing plate can suppress curl, 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 predetermined 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 significantly shortening the time for bonding the protective films having different moisture permeability to the polarizer as well as suppressing curls is required.

An object of the present invention is to provide a method capable of efficiently producing a polarizing plate by improving the adhesion speed between the polarizer and the protective film having low moisture permeability.

Another object of the present invention is to provide a method for producing a polarizing plate which can prevent curling of the polarizing plate.

1. A method of manufacturing a polarizing plate comprising using a polarizer having a moisture content of 5% by weight or more and less than 8% by weight in bonding two kinds of protective films having different moisture permeability to a polarizer with an aqueous adhesive.

2. In the above 1, the moisture content of the polarizer is a manufacturing method of 5 to 7% by weight polarizer.

3. In the above 1, one of the protective film is a manufacturing method of a polarizing plate having a water vapor transmission rate of 500 to 1,000g / ㎡ · day at 40 ℃ and 90% RH.

4. In the above 3, the protective film is a manufacturing method of the polarizing plate is a cellulose resin.

5. In the above 3, the other one of the protective film is a manufacturing method of a polarizing plate having a moisture permeability of 5 to 300g / ㎡ · day at 40 ℃ and 90% RH.

6. In the above 5, the protective film is a manufacturing method of the polarizing plate is selected from the group consisting of polyester resin, acrylic resin, polyimide resin, norbornene resin and polyolefin resin.

7. The method for producing a polarizing plate according to the above, wherein the aqueous adhesive contains a polyvinyl alcohol resin and a crosslinking agent.

In the polarizing plate manufacturing method of the present invention, the adhesion speed between the polarizer and the protective film having low moisture permeability is improved, thereby increasing productivity.

The method of manufacturing a polarizing plate of the present invention has an effect of preventing curling of the polarizing plate by reducing a difference in speed at which a protective film having high moisture permeability and a protective film having low moisture permeability are adhered to the polarizer.

The method of manufacturing a polarizing plate of the present invention is advantageous in producing a thinner and larger polarizing plate by preventing curling.

The manufacturing method of the polarizing plate of this invention is advantageous also in the aspect of equipment, such as shortening an adhesion time and shortening a length of a drying furnace.

In the present invention, in bonding two kinds of protective films having different moisture permeability to the polarizer with an aqueous adhesive, a polarizer having a moisture content of 5% by weight or more and less than 8% by weight is used to improve the adhesion speed between the polarizer and the protective film having low moisture permeability. The present invention relates to a method of manufacturing a polarizing plate which can prevent curling of the polarizing plate by reducing the difference in speed at which the protective film having high moisture permeability and the protective film having low moisture permeability are adhered to the polarizer.

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

In the present invention, the polarizer having a moisture content of 5% by weight or more and less than 8% by weight is used in manufacturing the polarizing plate. 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.

This polyvinyl alcohol-based resin is formed into a film and used as a polarizer. The film forming method of the polyvinyl alcohol-based resin is not particularly limited, and various known methods can be used. The film thickness of the polyvinyl alcohol-based resin is not particularly limited, and may be, for example, 10 to 150 μm.

A polarizer is normally manufactured through the process of uniaxial stretching of the above-mentioned polyvinyl alcohol-type film, the process of dyeing and adsorb | sucking with this color pigment, the process of treating with boric acid aqueous solution, and the process of washing with water and drying.

The process of uniaxially stretching the polyvinyl alcohol-based film may be performed before dyeing, simultaneously with dyeing, or after dyeing. If uniaxial stretching is carried out after dyeing, it may be carried out before or during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these plural steps. Uniaxial stretching may use rolls or thermal rolls having different circumferential speeds, and may be dry stretching in the air or wet stretching in a state swelled with a solvent. The draw ratio is usually 3 to 8 times.

For the process of dyeing the stretched polyvinyl alcohol-based film with a dichroic dye, for example, a method of immersing the polyvinyl alcohol-based film in an aqueous solution containing a dichroic dye may be used. Specific examples of dichroic dyes include iodine or dichroic dyes. In addition, the polyvinyl alcohol-based film is preferably swelled by dipping in water before dyeing.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type film in the dyeing aqueous solution containing iodine and potassium iodide can be used normally. Usually, the content of iodine in the aqueous solution for dyeing is 0.01 to 1 part by weight based on 100 parts by weight of water (distilled water), and the content of potassium iodide is 0.5 to 20 parts by weight based on 100 parts by weight of water. The temperature of the aqueous solution for dyeing is usually 20 to 40 ° C., and the immersion time, for example, the dyeing time is usually 20 to 1800 seconds.

On the other hand, in the case of using a dichroic organic dye as a dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based film in an aqueous dyeing solution containing a water-soluble dichroic organic dye can be used. The content of the dichroic organic dye in the aqueous solution for dyeing is usually 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^-3 to 1 part by weight based on 100 parts by weight of water. The aqueous dyeing solution may further contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution for dyeing is usually 20 to 80 ° C., and the immersion time such as dyeing time is usually 10 to 1,800 seconds.

Boric acid treatment of the dyed polyvinyl alcohol-based film can be carried out by immersing in a boric acid-containing aqueous solution. Usually, the content of boric acid in the aqueous solution containing boric acid is 2 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of water. The boric acid-containing aqueous solution in the case of using iodine as a dichroic dye preferably contains potassium iodide, and its content is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight with respect to 100 parts by weight of water. The temperature of the boric acid-containing aqueous solution is 50 ° C or higher, preferably 50 to 85 ° C, more preferably 60 to 80 ° C, and the immersion time is 60 to 1,200 seconds, preferably 150 to 600 seconds, more preferably It is preferable that it is 200 to 400 seconds.

After the boric acid treatment, the polyvinyl alcohol-based film is washed with water and dried. Washing treatment may be performed by immersing the boric acid-treated polyvinyl alcohol-based film in water, the temperature of the water during the washing treatment is 5 to 40 ℃, immersion time is 1 to 120 seconds. The polarizer can be obtained by drying after washing with water. The drying treatment may be generally performed using a hot air dryer or a far infrared heater, and the drying treatment temperature is usually 30 to 100 ° C, preferably 50 to 80 ° C, and the drying time is usually 60 to 600 seconds, preferably 120 to 80 ° C. 600 seconds is good.

According to the method as described above, in the present invention, the moisture content of the polarizer is prepared to be 5% by weight or more and less than 8% by weight, preferably 5% by weight or more and 7% by weight or less. When the moisture content is less than 5% by weight, the polarizer may be torn, and when the moisture content is more than 8% by weight, it is difficult to suppress curl when the protective film having different moisture permeability is bonded to both sides of the polarizer.

Moisture content of the polarizer may be performed by adjusting the drying temperature and drying time in the dyeing process, boric acid treatment process, water washing step used in the manufacture of the polarizer, the time immersed in the aqueous solution in the drying process.

The polarizer may have a thickness of 5 to 40 μm.

The production method of the present invention relates to bonding two kinds of protective films having different moisture permeability to a polarizer with an aqueous adhesive.

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. The high moisture permeability protective film means a protective film having a water vapor transmission rate of 500 to 1,000 g / m 2 · day at 40 ° C. and 90% RH, and specific examples thereof include cellulose resins such as diacetyl cellulose and triacetyl cellulose. have. In addition, the protective film having a low moisture permeability means a protective film having a water vapor transmission rate of 5 to 300 g / m 2 · day at 40 ° C. and 90% RH, and specific examples thereof include polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutyl. Polyester resins such as lenterephthalate; Polycarbonate resins; Acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene resins such as polystyrene and acrylonitrile-styrene copolymers; Polyolefin resins such as polyethylene, polypropylene, cyclo-based or norbornene-structured polyolefins, ethylene-propylene copolymers; Vinyl chloride-based resins; Amide resins such as nylon and aromatic polyamides; Polyimide resin; Polyether sulfone resin; Sulfone resins; Polyether sulfone resin; Polyether ether ketone resins; Sulfided polyphenylene resins; Vinyl alcohol-based resins; Vinylidene chloride-based resins; Vinyl butyral resin; Allyl resins; Polyoxymethylene resin; And a film selected from the group consisting of thermoplastic resins such as epoxy resins, and the like, and films composed of blends of the thermoplastic resins may also be used. Moreover, you may use the film which consists of thermosetting resins, such as a (meth) acrylic-type, a urethane type, an acryl urethane type, an epoxy type, a silicone type, or an ultraviolet curable resin.

The content of the thermoplastic resin in the protective film is 50 to 100% by weight, preferably 50 to 99% by weight, more preferably 60 to 98% by weight, most preferably 70 to 97% by weight. If the content is less than 50% by weight, it may not sufficiently express the inherent high transparency of the thermoplastic resin.

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 film are bonded with an aqueous adhesive. Specific examples of the water-based adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latexes, water-based polyurethanes, water-based polyesters, and the like. Among these, polyvinyl alcohol-based adhesives are preferable. The aqueous adhesive may suitably contain a crosslinking agent.

For example, a polyvinyl alcohol-based adhesive containing a crosslinking agent is usually used as an aqueous solution. The concentration of the aqueous solution is not particularly limited, but is 0.1 to 15% by weight, preferably 0.5 to 10% by weight, more preferably 0.5 to 5% by weight in consideration of coating property or standing stability.

The aqueous adhesive may further contain a coupling agent such as a silane coupling agent or a titanium coupling agent, various tackifiers, ultraviolet absorbers, antioxidants, heat stabilizers, stabilizers such as hydrolysis stability stabilizers, and the like.

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 the adhesive layer so that the thickness of the adhesive layer formed after drying in consideration of the content of solid content is 10 to 1,000 nm, preferably 40 to 600 nm. When the thickness is less than 10nm, the adhesion may be poor, and when the thickness is greater than 1,000nm, 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 because the deformation is applied 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, at 20 to 50 ° C. for 12 to 600 hours is preferable.

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, the shrinkage stress is generated in the direction of the film with high moisture permeability, resulting in a large curl. The moisture content of this polarizer is 10-30 weight% normally.

However, the polarizer having a moisture content of 5 to 8% by weight of the present invention is provided with a protective film having a different moisture permeability and then dried to move moisture of the water-based adhesive applied to the protective film with low moisture permeability to the polarizer, thereby providing a polarizer and a moisture permeability. As the adhesion speed (drying speed) between the low protection films is improved, the difference in the adhesion speeds of the protection films provided on both polarizers is reduced, so that the shrinkage stress is suppressed to suppress the occurrence of curl.

In the polarizing plate of the present invention, a surface treatment layer such as a hard coating layer, an antireflection layer, an antiglare layer, an antistatic layer and the like may be further laminated on the other side of the protective film not bonded to the polarizer. In addition, the optical functional film may be further laminated by the pressure-sensitive adhesive layer, and specific examples of the optical functional film may include an optical compensation film having a liquid crystal compound or a polymer compound thereof oriented on the surface of a substrate, and any polarized light is transmitted therethrough. The polarized light having the opposite property is a reflective polarization separating film that is reflected, a retardation film containing polycarbonate resin, a retardation film containing cyclic polyolefin-based resin, a rectangular functional part having an uneven shape on the surface of the film, and anti-reflective treatment The additional film, the reflective film which has a reflection function on the surface, the semi-transmissive film which has both a reflection function and a transmission function, etc. are mentioned.

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

Hereinafter, the present invention will be described in more detail with reference to Examples. It is apparent that the embodiments are merely examples of the present invention and do not limit the scope of 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]

Production Example 1. Preparation of polarizer (water content 4% by weight)

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. Thereafter, the weight ratio of potassium iodide / boric acid / distilled water was immersed in an aqueous solution of 72 ° C. having 8.5 / 8.5 / 100 for 300 seconds, washed with distilled water at 26 ° C. for 20 seconds, and dried at 80 ° C. for 4 minutes to iodine on a PVA film. The adsorbed oriented polarizer was prepared. The moisture content of a polarizer is 4 weight%.

Production Example 2. Preparation of Polarizer (water content 5 wt%)

It was carried out in the same manner as in Preparation Example 1, but dried for 3 minutes at 80 ℃ to prepare a polarizer having a moisture content of 5% by weight.

Preparation Example 3 Preparation of Polarizer (Moisture 6 wt%)

It was carried out in the same manner as in Preparation Example 1, but dried for 2 minutes at 80 ℃ to prepare a polarizer having a moisture content of 6% by weight.

Production Example 4. Preparation of polarizer (water content 7% by weight)

The same method as in Preparation Example 1 was performed, but the resultant was washed with distilled water at 26 ° C. for 60 seconds and dried at 80 ° C. for 3 minutes to prepare a polarizer having a moisture content of 7 wt%.

Production Example 5. Preparation of polarizer (water content 9% by weight)

The same method as in Preparation Example 1 was performed, but the mixture was washed with distilled water at 26 ° C. for 90 seconds and dried at 65 ° C. for 3 minutes to prepare a polarizer having a moisture content of 9 wt%.

Production Example 6. Preparation of polarizer (water content 10% by weight)

A polarizer having a moisture content of 10 wt% was prepared in the same manner as in Preparation Example 1, but washed with distilled water at 26 ° C. for 105 seconds and then dried at 55 ° C. for 2 minutes.

Preparation Example 7 Preparation of PVA Adhesive

100 parts by weight of distilled water, 3 parts by weight of carboxyl group-modified PVA resin (Kurarepobal KL318, Kuraray Co., Ltd.) and 1.5 parts by weight of polyamide epoxy resin (Sumirez resin 650 (30% solids content), Sumitomo Chemical Co., Ltd.) The adhesive was prepared by the addition.

Preparation Example 8 Pretreatment of Protective Film

(1) Preparation of triacetyl cellulose 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.

(2) Production of norbornene-based 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.

(3) Preparation of polyester film

One side of the polyester film (40 μm) was subjected to corona treatment with a discharge amount of 200 w · min / m 2, and the water vapor transmission rate was 23 g / m 2 day.

Examples 1 and 2

The corona treated norbornene-based film was placed on one side of each of the PVA polarizers prepared in Production Examples 2 and 3, and the saponified triacetylcellulose film was placed on the other side of the PVA-based polarizer. After applying the PVA-based adhesive prepared in Preparation Example 7 between the two films were bonded using a nip roll. The bonded flat plate was placed in a hot air oven, and dried at 70 ° C. until the time of adhesion.

Example 3

In the same manner as in Examples 1 and 2, but one side of the polarizer prepared in Preparation Example 4 was placed on the triacetyl cellulose film treated, the other side was prepared a polarizing plate by placing a polyester-based film .

Comparative Examples 1 to 3

In the same manner as in Examples 1 to 3, except that the corona-treated norbornene-based film is placed on one side of the polarizers prepared in Production Examples 1, 5 and 6, the other side of the PVA-based polarizer is saponification treatment The triacetyl cellulose film was positioned to prepare a polarizing plate.

Test Example

1. Measurement of Moisture Content of Polarizer

Moisture content (weight%) of polarizer = [(A-B) / B] x 100

A: weight of polarizer before bonding with protective film

B: The polarizer weight after leaving the polarizer of A to stand at 120 degreeC for 7 hours.

2. Curling amount of polarizer

The concave side of the curled sample is placed face up on a reference plane, such as a plane on the table, and the humidity is adjusted for 48 hours under an atmosphere of 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 of a 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.

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. . In this case, the adhesion time of the polarizing plate was based on the time when both the first and second protective films were bonded.

Sample Protective film Polarizer Moisture Content (wt%) Polarizer One 2 Curl
(Mm) Adhesion time
(second) condition Example 1 Production Example
8-1 Production Example
8-2 5 7 20 Curl relief Example 2 Production Example
8-1 Production Example
8-2 6 8 25 Curl relief Example 3 Production Example
8-1 Production Example
8-3 7 13 30 Curl relief Comparative Example 1 Production Example
8-1 Production Example
8-2 4 - - Polarizer tearing Comparative Example 2 Production Example
8-1 Production Example
8-2 9 29 55 Deteriorate curl Comparative Example 3 Production Example
8-1 Production Example
8-2 10 32 65 Deteriorate curl

As shown in the above table, according to the present invention, the polarizing plates of Examples 1 to 3, which are manufactured with a polarizer having a moisture content of 5 wt% or more and less than 8 wt%, have a shorter adhesion time (drying time) and curl than those of the polarizing plates of Comparative Examples 1-3. This was suppressed. On the other hand, when using a polarizer with a low moisture content as shown in Comparative Example 1, it was confirmed that the polarizer is torn.

When the polarizing plate of the present invention is used in the manufacturing process of the polarizing plate and the liquid crystal display device to improve the adhesion speed, it is expected that the production yield is improved and productivity is significantly increased by improving the curl of the product.

As described above, the present invention is applicable to the manufacturing process of various image display devices such as a liquid crystal display device that requires a polarizing plate that shortens the adhesion time of the protective film and the polarizer.

Claims (7)

A method of manufacturing a polarizing plate comprising using a polarizer having a moisture content of 5% by weight or more and less than 8% by weight in bonding two kinds of protective films having different moisture permeability to a polarizer with an aqueous adhesive. The method of manufacturing a polarizing plate according to claim 1, wherein a water content of the polarizer is 5 to 7% by weight. The method of claim 1, wherein one of the protective films has a water vapor transmission rate of 500 to 1,000 g / m 2 · day at 40 ° C. and 90% RH. The method of claim 3, wherein the protective film is a cellulose resin. The method of manufacturing a polarizing plate according to claim 3, wherein the other one of the protective films has a moisture permeability of 5 to 300 g / m 2 · day at 40 ° C. and 90% RH. The method of claim 5, wherein the protective film is selected from the group consisting of polyester resins, acrylic resins, polyimide resins, norbornene resins, and polyolefin resins. The method for producing a polarizing plate according to any one of claims 1 to 6, wherein the aqueous adhesive contains a polyvinyl alcohol resin and a crosslinking agent.