KR20160094983A - Polarizer with few air bubble defects - Google Patents

Abstract

A polarizer composed of a polyvinyl alcohol-based resin having a pore size of 100 m or more in an absorption axis direction of 10 / m 2 or less, a polarizing laminated film in which the polarizer is laminated on at least one surface of a base film, A polarizing plate laminated with a transparent protective film, and a method of producing the polarizing plate.

Description

[0001] POLARIZERS WITH FEW AIR BUBBLE DEFECTS [0002]

The present invention relates to a polarizer having few bubble defects and a method of manufacturing the same.

BACKGROUND ART [0002] In recent years, a polarizing plate has been widely used as an optical element of a liquid crystal display device by being incorporated in a liquid crystal display of a liquid crystal television, a mobile phone, or a personal computer. In recent years, a thin polarizer has been developed to reduce the size and weight of these liquid crystal display devices. A method has been proposed in which a polyvinyl alcohol based resin layer is formed on the surface of a substrate film by using an aqueous solution of a polyvinyl alcohol based resin, followed by stretching and subsequent dyeing to produce a polarizer and a polarizing plate (see Patent Documents 1 and 2) 2).

[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-338329 [Patent Document 2] JP-A-2009-93074

In the method for producing the polarizer and the polarizing plate, when an aqueous solution of a polyvinyl alcohol-based resin is used, the polyvinyl alcohol-based resin in the process of preparing the aqueous solution is easy to dry air bubbles and the polyvinyl alcohol- A circular concave defect caused by bubbles or a void caused by an oval or linear bubble defect generated in the stretching direction of the resin layer after stretching is formed on the surface of the polyvinyl alcohol type resin layer to be formed The present inventor has found. The present inventors provide a polarizer having a small void due to such bubble defects, a polarizing laminated film comprising such a polarizer, and a process for producing the same.

The present invention provides a polarizer comprising a polyvinyl alcohol-based resin having a pore size of 100 m or more in an absorption axis direction of 10 pores / m 2 or less. Further, the present invention provides a polarizing plate in which a transparent protective film is laminated on at least one surface of a polarizing laminated film and a polarizer in which such a polarizer is laminated on at least one surface of a base film.

A polarizing laminated film in which the length of the polarizer in the direction of the absorption axis is 100 m or more and 10 pores / m 2 or less is typically manufactured by a manufacturing method including the following steps (a) to (c).

(A) A resin layer is formed on at least one surface of a base film by applying an aqueous solution of a polyvinyl alcohol-based resin subjected to vacuum degassing to obtain a laminated film having a resin layer composed of a polyvinyl alcohol-based resin formed on at least one surface of the base film The process,

(B) a stretching step of stretching the laminated film to obtain a stretched film,

(C) A dyeing step of dyeing a resin layer made of a polyvinyl alcohol-based resin of a stretched film with a dichroic dye to form a polarizer layer.

The present invention relates to a process (joining step) of joining a transparent protective film to a surface of the polarizing layer of this polarizing laminated film opposite to the base film side to obtain a multilayered film, a step of peeling the base film from the multilayered film ), Wherein a transparent protective film is formed on one side of the polarizer.

According to the present invention, when the polarizer is produced, the aqueous solution of the polyvinyl alcohol-based resin is depressurized and removed to remove the aqueous solution of the polyvinyl alcohol-based resin as a coating liquid on the base film to form the polyvinyl alcohol-based resin layer , The bubbles in the coating liquid rupture, and generation of circular concave defects can be reduced in the coating layer. As a result, it has been found that even when a laminated film comprising a base film and a polyvinyl alcohol-based resin layer after being coated is stretched, a polarizer in which generation of elliptical or linear voids due to bubble defects is suppressed, which occurs in the stretching direction, A polarizing laminated film can be provided.

1 is a schematic sectional view showing an example of a basic layer structure of a polarizing laminated film according to the present invention.
2 is a schematic cross-sectional view showing an example of a basic layer structure of a polarizing plate according to the present invention.
3 is a flow chart showing an embodiment of a method for producing the polarizing laminated film shown in Fig.
4 is a flow chart showing an embodiment of a method of manufacturing the polarizing plate shown in Fig.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

≪ Constitution of Polarizing Laminated Film >

1 is a schematic sectional view showing an example of a basic layer structure of a polarizing laminated film according to the present invention. The polarizing laminated film 10 includes a base film 11 and a polarizer layer 12 formed on one side of the base film 11. The polarizer layer 12 is formed on one side of the base film 11, The polarizer layer 12 is formed of a polyvinyl alcohol-based resin having a thickness of 10 mu m or less and having a dichroic dye attracted and oriented.

Hereinafter, each component will be described in detail.

[Base film]

As the material of the base film 11, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, stretchability and the like is used. Specific examples of such thermoplastic resins include cellulose ester resins such as cellulose triacetate, polyester resins, polyether sulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins (Meth) acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.

As the material of the base film, it is preferable that at least one selected from the group consisting of a cellulose ester resin, a polyolefin resin, a cyclic polyolefin resin and a (meth) acrylic resin is included.

In the present specification, "(meth) acryl" means acryl or methacryl.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of such a cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Of these, cellulose triacetate is particularly preferable. Cellulose triacetate is commercially available in many products, and is advantageous in terms of availability and cost. Examples of commercially available products of cellulose triacetate include FUJITAC (registered trademark) TD80 (manufactured by Fuji Film), Fujite (registered trademark) TD80UF (manufactured by Fuji Film) (Manufactured by Konica Minolta Opto Co., Ltd.), KC4UY (manufactured by Konica Minolta Opto Co., Ltd.), and the like can be given. have.

Examples of the polyolefin-based resin include polyethylene and polypropylene. When a base film made of polypropylene is used, it is preferable to stably stretch at a high magnification. As the cyclic polyolefin-based resin, a norbornene-based resin is preferably used. The cyclic polyolefin-based resin is a generic name of a resin polymerized by using a cyclic olefin as a polymerization unit, and examples thereof include those described in JP-A-1-240517, JP-A-3-14882, -122137, and the like. Specific examples include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and? -Olefins such as ethylene and propylene (typically, random copolymers) and unsaturated carboxylic acids and their Graft polymers modified with derivatives, and hydrides thereof. Specific examples of the cyclic olefin include norbornene-based monomers.

As the cyclic polyolefin-based resin, various products are commercially available. Specific examples thereof include: Topas (registered trademark) (manufactured by Ticona), ATON (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (manufactured by Nippon Zeon Corporation), Zeonex (Registered trademark) (manufactured by Nippon Zeon Co., Ltd.) and APEL (registered trademark) (manufactured by Mitsui Chemicals, Inc.).

As the (meth) acrylic resin, any suitable (meth) acrylic resin may be employed. Examples thereof include poly (meth) acrylates such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate- (meth) acrylate copolymers, methyl methacrylate- Styrene copolymer (MS resin), a polymer having an alicyclic hydrocarbon group (e.g., a methyl methacrylate-cyclohexyl copolymer, a methacrylic acid methyl- (meth) acrylate copolymer, ) Acrylate norbornyl copolymer). Preferable examples include poly (meth) acrylate C _1-6 alkyl such as methyl poly (meth) acrylate. As the (meth) acrylic resin, a methyl methacrylate resin having a main component (50 to 100% by weight, preferably 70 to 100% by weight) of methyl methacrylate is used.

In addition to the above-mentioned thermoplastic resin, any appropriate additives may be added to the base film 11. Examples of such an additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a releasing agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment and a colorant. The content of the thermoplastic resin exemplified above in the base film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, particularly preferably 70 to 97% by weight %to be. When the content of the thermoplastic resin in the base film is less than 50% by weight, high transparency and the like inherently possessed by the thermoplastic resin may not be sufficiently developed.

The thickness of the base film 11 can be appropriately determined, but it is preferably 1 to 500 탆, more preferably 1 to 300 탆, and more preferably 5 to 200 탆 in terms of workability such as strength and handleability desirable. The thickness of the base film 11 is most preferably 5 to 150 mu m.

The base film preferably has a melting point of 110 캜 or higher so that it can be stretched in a temperature range suitable for stretching the polyvinyl alcohol-based resin. Preferably, those having a melting point of 130 ° C or higher are used. If the melting point of the base film is less than 110 占 폚, the base film tends to melt in the stretching step (S20) described later, so that the stretching temperature can not be increased sufficiently, and stretching exceeding 5 times becomes difficult. The melting point of the base film is a value measured at a heating rate of 10 占 폚 / min based on ISO3146.

The base film 11 may be subjected to a corona treatment, a plasma treatment, a flame treatment, or the like on at least the surface of the base film 11 on which the polarizing layer 12 is formed, in order to improve the adhesion with the polarizer layer 12. In order to improve the adhesion, a thin layer such as a primer layer may be formed on the surface of the base film 11 on the side where the polarizer layer 12 is formed.

[Polarizer layer]

The polarizer of the present invention is a polarizer made of a polyvinyl alcohol-based resin having a pore size of 100 m or more in the absorption axis direction of 10 m 2 / m 2 or less. The thickness of such a polarizer may be set to 10 占 퐉 or less, and further to 7 占 퐉 or less. A thin polarizing laminated film having a thickness of the polarizer layer 12 of 10 m or less can be produced.

Specifically, the polarizer layer 12 is formed by adsorbing and orienting a dichroic dye in a uniaxially stretched polyvinyl alcohol-based resin layer. As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. As the polyvinyl acetate resin, a copolymer of vinyl acetate, which is a homopolymer of vinyl acetate, with other monomers copolymerizable with vinyl acetate, and the like are exemplified. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is 99.0 mol% or less. In the present invention, the polyvinyl alcohol-based resin having a saponification degree of 99.0 mol% or less can maintain a constant dyeing speed even when uniaxial stretching exceeds 5 times. Therefore, a thin film- There is an advantage that it can be produced efficiently. On the other hand, when a polyvinyl alcohol-based resin having a degree of saponification of more than 99.0 mol% is used, the rate of dyeing is remarkably slowed, and a polarizing laminated film having sufficient polarization performance may not be obtained. There is a case where a problem of requiring a time that is several times as large as the number

The degree of saponification of the polyvinyl alcohol-based resin is preferably 90 mol% or more, and more preferably 94 mol% or more. If the degree of saponification is less than 90 mol%, the strength such as water resistance may not be sufficient.

The term "saponification degree" as used herein refers to the ratio of the unit acyl groups contained in the polyvinyl acetate-based resin as the raw material of the polyvinyl alcohol-based resin to the hydroxyl group by the saponification process as a unit ratio (mol%) and is a numerical value defined by the following formula . It can be obtained by the method prescribed in JIS K 6726 (1994).

Saponification degree (mol%) = (number of hydroxyl groups) / (number of hydroxyl groups + number of acetic acid groups) x 100

The higher the degree of saponification, the higher the ratio of hydroxyl groups, that is, the lower the proportion of acetic acid groups that inhibit crystallization. The polyvinyl alcohol-based resin used in the present invention is not particularly limited as long as the degree of saponification is 99.0 mol% or less, and may be modified polyvinyl alcohol partially modified. Examples of the modified polyvinyl alcohol include polyvinyl alcohol resins such as polyvinyl alcohol resins in an amount of several percent by weight of an unsaturated carboxylic acid such as olefin such as ethylene or propylene, acrylic acid, methacrylic acid, crotonic acid, alkyl ester of unsaturated carboxylic acid, And the like. The average degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, but is preferably from 100 to 10000, more preferably from 1500 to 10000.

(Saponification degree: 98.0 to 99.0 mol%), PVA117 (saponification degree: 98.0 to 99.0 mol%), and PVA624 (saponification degree: 95.0 to 95.0 mol%) manufactured by Kuraray Co., Ltd. are used as the polyvinyl alcohol- 96.0 mol%) and PVA 617 (saponification degree: 94.5 to 95.5 mol%); AH-26 (saponification degree: 97.0 to 98.8 mol%), AH-22 (saponification degree: 97.5 to 98.5 mol%) and NH-18 (saponification degree: 98.0 to 99.0 mol%, manufactured by Nippon Gosei Kagaku Kogyo Co., %) And N-300 (saponification degree: 98.0 to 99.0 mol%); (Saponification degree: 98.0 to 99.0 mol%), JF-17L (saponification degree: 98.0 to 99.0 mol%) and JF-20 (saponification degree: 98.0 to 99.0 mol%) of Nippon Sakubi- ) And the like.

Such a polyvinyl alcohol-based resin may be coated on a substrate to form a resin layer, which can be used for producing the polarizer layer 12 according to the present invention. The method of forming the resin layer of the polyvinyl alcohol-based resin is such that a solution of the polyvinyl alcohol-based resin is coated on the base film 11 to form a resin layer in order to easily obtain the polarizer layer 12 having a desired thickness Is preferable. The polarizer layer 12 is uniaxially stretched at a stretching magnification of preferably not less than 5 times, more preferably not less than 5 times and not more than 8 times.

Wherein a polarizer layer made of a polyvinyl alcohol based resin is formed on at least one side of the base film and the number of pores having a length in the absorption axis direction of 100 m or more of the polarizer layer is 10 / Will be described below.

An aqueous solution of a polyvinyl alcohol-based resin subjected to vacuum degassing is coated on at least one surface of a base film to obtain a laminated film having a resin layer made of a polyvinyl alcohol-based resin on at least one surface of the base film, Explain.

The aqueous solution of the polyvinyl alcohol-based resin coated on the base film usually contains 4 wt% to 10 wt% of polyvinyl alcohol-based resin, and preferably 6 wt% to 9 wt%. If it is 4 wt% or less, the amount of heat is required to be higher than that in the case of drying, so that it is necessary to lower the line speed and the productivity may be deteriorated. If it is 10 wt% or more, gelation tends to occur and storage property may be deteriorated. As the polyvinyl alcohol-based resin, those exemplified in the description of the polarizer are used.

As the aqueous solution of the polyvinyl alcohol-based resin, an aqueous solution of defoaming polyvinyl alcohol-based resin is preferable, and defoaming by decompression is preferable as defoaming method because of the good removal efficiency of bubbles. Since the PVA aqueous solution is very liable to foam and the foams that are generated are difficult to break, the pressure is reduced in a state of being kept so as not to mix the bubbles generated by the decompression into the liquid again, , And a method of waiting for bubbles to be removed from the aqueous solution is more preferable.

In the defoaming process of the present invention, a decompression method of sucking by a vacuum pump is used. The container for de-embedding is not particularly specified, but may be any container that can withstand the decompression, and can be easily carried out. Decompression is usually preferable because the processing time is shortened by lowering the pressure (gauge pressure) in the container as low as possible. The pressure (gauge pressure) in the container is usually set to -0.04 MPa or less, preferably -0.05 MPa or less, more preferably -0.08 MPa or less, and particularly preferably -0.09 MPa or less. The treatment time is typically 30 minutes or more, preferably 60 minutes or more, more preferably 120 minutes or more, but it may be long without deteriorating the productivity.

The temperature of the coating liquid to be fed when an aqueous solution of the defoaming polyvinyl alcohol-based resin (also referred to as a PVA aqueous solution or a coating liquid) is applied is such that the substrate is relaxed when the coating liquid comes into contact with the substrate and the polyvinyl alcohol The upper limit may be set so as not to affect the film thickness precision of the resin layer and the lower limit may be set so that gelation of the PVA aqueous solution does not occur. The temperature of the coating solution is usually 10 to 80 캜, preferably 15 to 60 캜, more preferably 20 to 40 캜.

In the present invention, the production of the PVA aqueous solution and the coating process are not necessarily continuous, but the polyvinyl alcohol resin is dissolved in water, the resultant PVA aqueous solution is once transferred to a container for transportation such as a drum or container, The PVA aqueous solution may be transported and supplied. In this way, the equipment (dissolution facility) for dissolving the polyvinyl alcohol-based resin and the facility for coating the base material of the polyvinyl alcohol-based resin (coating facility) can be divided to make the equipment compact .

[Resin layer forming step (S10)]

Here, a resin layer (also referred to as a polyvinyl alcohol-based resin layer or a resin layer) made of a polyvinyl alcohol-based resin is formed on one surface of the base film.

The material suitable for the base film is as described in the description of the constitution of the polarizing laminated film. On the other hand, in the present embodiment, the material of the polyvinyl alcohol-based resin suitable for forming the resin layer is as described in the description of the constitution of the polarizing laminated film.

The resin layer of the polyvinyl alcohol-based resin is usually formed by coating an aqueous solution of a polyvinyl alcohol-based resin on one surface of the base film and drying the solvent such as water by evaporation. By forming the resin layer in this way, it becomes possible to form the resin layer thin. Examples of the method of coating an aqueous solution of a polyvinyl alcohol resin on a base film include a roll coating method such as wire bar coating method, reverse coating and gravure coating, a die coating method, a comma coating method, a lip coating method, a spin coating method, Method, a fountain coating method, a dipping method, a spraying method, and the like can be suitably selected and employed by a known method. A comma coating method (knife coater), a die coating method and a lip coating method are preferable. The drying temperature is, for example, 50 ° C to 200 ° C, and preferably 60 ° C to 150 ° C. The drying time is, for example, 2 minutes to 20 minutes.

The thickness of the resin layer to be formed is usually a thickness of more than 3 占 퐉 in consideration of the dyeability after stretching. When the thickness of the finally obtained polarizer layer is 10 占 퐉 or less, the thickness of the resin layer to be formed is usually 30 占 퐉 or less. The thickness of the resin layer to be formed is preferably 5 占 퐉 to 20 占 퐉.

Further, in order to improve the adhesion between the base film and the polyvinyl alcohol-based resin layer, a primer layer may be formed between the base film and the resin layer. The primer layer is preferably formed from a composition containing a polyvinyl alcohol-based resin and a crosslinking agent from the viewpoint of adhesion.

[Stretching step (S20)]

A drawing process for obtaining a drawn film by stretching a laminated film obtained by laminating a polyvinyl alcohol-based resin layer on a substrate film thus obtained will be described below. The laminated film composed of the base film and the resin layer is uniaxially stretched so as to have a stretching ratio exceeding 5 times with respect to the length of the laminated film before the stretching step to obtain a stretched film. Preferably, the uniaxial stretching is performed so that the stretching magnification is more than 5 times and not more than 8 times. If the stretching magnification is 5 times or less, the resin layer made of the polyvinyl alcohol-based resin is not sufficiently oriented, and as a result, the degree of polarization of the polarizer layer does not become sufficiently high. On the other hand, when the draw ratio is more than 8 times, the laminated film tends to be broken at the time of stretching, and the thickness of the drawn film becomes thinner than necessary, which may lower the workability and handling property in the subsequent process. The stretching process in the stretching process (S20) is not limited to stretching in one stage but may be performed in multiple stages. In the case of multi-step drawing, the drawing process is performed so that the sum of the front ends of the drawing process becomes a drawing magnification exceeding 5 times.

In the stretching step (S20) in the present embodiment, it is preferable to perform the longitudinal stretching treatment in the longitudinal direction of the laminated film. However, in the case where the polarizing performance is not so required, It may be stretched. Examples of the longitudinal stretching method include a roll-to-roll stretching method, a compression stretching method, and a stretching method using a tenter. The stretching treatment is not limited to the longitudinal stretching treatment but may be an oblique stretching treatment or the like. It is also preferable to be free-end uniaxial stretching.

The stretching treatment can be carried out by any of a wet stretching method and a dry stretching method, but it is preferable to use a dry stretching method in that the temperature at which a laminated film is stretched can be selected from a wide range.

In the present embodiment, it is preferable to conduct the stretching treatment in the temperature range of -30 캜 to + 5 캜 of the melting point of the base film. More preferably, the stretching treatment is performed at a temperature ranging from -25 캜 to the melting point of the base film. When the stretching temperature is lower than -30 캜 of the melting point of the base film 11, it is difficult to stretch at a high magnification exceeding 5 times. If the stretching temperature exceeds +5 캜 of the melting point of the base film, stretching becomes difficult due to melting of the base film. On the other hand, the stretching temperature is within the above range, more preferably 120 deg. When the stretching temperature is 120 ° C or higher, even if the stretching ratio is higher than 5 times, there is no difficulty in the stretching treatment. The temperature adjustment of the stretching treatment is usually performed by adjusting the temperature of the heating furnace.

[Dyeing process (S30)]

The dyeing step of staining a resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer will be described below. Here, the polyvinyl alcohol-based resin layer of the stretched film is dyed with a dichroic dye. Examples of the dichroic dye include iodine and organic dyes. Examples of the organic dyes include red BR, red LR, red R, pink LB, rubin BL, bordeaux GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, violet LB, violet B, H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky Blue, Direct First Orange S, First Black and the like can be used. These dichroic substances may be used alone or in combination of two or more.

The dyeing step is carried out, for example, by immersing the entire stretched film in a solution (dyeing solution) containing the dichroic dye. As the dyeing solution, a solution obtained by dissolving the dichroic dye in a solvent can be used. As the solvent of the dyeing solution, water is generally used, but an organic solvent having compatibility with water may be further added. The concentration of the dichroic dye is preferably 0.01 wt% to 10 wt%, more preferably 0.02 wt% to 7 wt%, and particularly preferably 0.025 wt% to 5 wt%.

When iodine is used as the dichroic dye, it is preferable to further add iodide because the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide and the like. The addition ratio of these iodides is preferably 0.01 to 20% by weight in the dyeing solution. Among iodides, it is preferable to add potassium iodide. When potassium iodide is added, the ratio of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, more preferably 1: 6 to 1:80, more preferably 1: 7 to 1: 70.

The immersion time of the stretched film to the dyeing solution is not particularly limited, but is preferably in the range of usually 15 seconds to 15 minutes, more preferably 1 to 3 minutes. The temperature of the dyeing solution is preferably in the range of 10 캜 to 60 캜, and more preferably in the range of 20 캜 to 40 캜. In the dyeing process, excess dyeing solution may be washed with pure water.

In the dyeing step, the dyeing may be followed by a crosslinking treatment. The crosslinking treatment can be carried out, for example, by immersing the drawn film in a solution (crosslinking solution) containing a crosslinking agent. As the crosslinking agent, conventionally known materials can be used. Examples thereof include boron compounds such as boric acid and borax, and glyoxal and glutaraldehyde. These may be used alone or in combination of two or more.

As the crosslinking solution, a solution in which a crosslinking agent is dissolved in a solvent can be used. As the solvent, for example, water may be used, but an organic solvent compatible with water may also be contained. The concentration of the cross-linking agent in the cross-linking solution is not limited thereto, but is preferably in the range of 1 to 20 wt%, and more preferably 6 to 15 wt%.

Iodide may be added to the crosslinking solution. By adding iodide, the polarization characteristics in the plane of the polyvinyl alcohol-based resin layer can be made more uniform. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. The content of iodide is usually 0.05 to 15% by weight, more preferably 0.5 to 8% by weight.

The immersing time of the stretched film in the crosslinking solution is preferably 15 seconds to 20 minutes, more preferably 30 seconds to 15 minutes. The temperature of the crosslinking solution is preferably in the range of 10 to 80 캜.

Finally, it is preferable to carry out a washing step and a drying step. As the washing step, a water washing treatment can be carried out. The water washing treatment can be usually carried out by immersing the drawn film in purified water such as ion-exchanged water or distilled water. The water washing temperature is usually in the range of 3 캜 to 50 캜, preferably 4 캜 to 20 캜. The immersion time is usually 2 seconds to 300 seconds, preferably 3 seconds to 240 seconds.

The cleaning step may be a combination of a cleaning treatment with a iodide solution and a water cleaning treatment, or a solution in which a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, or propanol is blended.

After the cleaning step, it is preferable to carry out the drying step. As the drying step, any appropriate method (for example, natural drying, blow drying, and heat drying) may be employed. For example, in the case of heat drying, the drying temperature is usually 20 ° C to 95 ° C, and the drying time is usually about 1 minute to 15 minutes. By the above dyeing step (S30), the polyvinyl alcohol-based resin layer has a function as a polarizer. In the present specification, a polyvinyl alcohol-based resin layer having a function as a polarizer is referred to as a polarizer layer, and a laminate having a polarizer layer on a base film is referred to as a polarizing laminated film.

In this embodiment, an aqueous solution of a polyvinyl alcohol-based resin having a degree of saponification of not more than 99.0 mol% in the polyvinyl alcohol-based resin layer and subjected to vacuum degassing is used, and in the stretching step (S20) , A good dyeing speed is maintained in the dyeing step (S30). On the other hand, in a resin layer using a polyvinyl alcohol-based resin having a high degree of saponification, the dyeing speed in the dyeing step (S30) is lowered, and dyeing tends to become insufficient.

≪ Configuration of Polarizer &

2 is a schematic cross-sectional view showing an example of a basic layer structure of a polarizing plate according to the present invention. The polarizing plate 13 includes a transparent protective film 14 and a polarizer layer 12 formed on one side of the transparent protective film 14. [ The polarizer layer 12 is formed of a polyvinyl alcohol-based resin having a thickness of 10 mu m or less and having a dichroic dye attracted and oriented. The degree of saponification of the polyvinyl alcohol-based resin is 99.0 mol% or less.

In the polarizing plate 13, the transparent protective film 14 and the polarizer layer 12 are bonded to each other with, for example, a pressure-sensitive adhesive or an adhesive layer. Hereinafter, each component will be described in detail.

[Transparent protective film]

The transparent protective film 14 may be a simple transparent protective film having no optical function and may be a transparent protective film having an optical function such as a retardation film or a brightness enhancement film. Examples of the material of the transparent protective film 14 include, but are not limited to, a cyclic polyolefin resin film, acetic acid cellulose resin film made of a resin such as triacetylcellulose or diacetylcellulose, polyethylene terephthalate, polyethylene naphthalate, (Meth) acrylic resin film, and polypropylene-based resin film, which are conventionally widely used in the art, such as a polyester-based resin film made of a resin such as polybutylene terephthalate, a polycarbonate-based resin film, have.

Examples of the cyclic polyolefin resin include commercially available products such as Topas TM (manufactured by Ticona), ATON TM (manufactured by JSR Corporation), ZEONOR TM (manufactured by Nippon Zeon Co., Ltd.) ZEONEX (manufactured by Nippon Zeon Co., Ltd.) and APEL (registered trademark) (manufactured by Mitsui Chemicals, Inc.) can be suitably used. When a film of such an annular polyolefin-based resin is formed into a film, known methods such as solvent casting method and melt extrusion method are suitably used. (Trade name) manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonoa (registered trademark) film A commercially available product of a film of a preformed cyclic polyolefin resin may be used.

The cyclic polyolefin-based resin film may be uniaxially stretched or biaxially stretched. By stretching, an arbitrary retardation value can be imparted to the cyclic polyolefin-based resin film. The stretching is usually carried out continuously while releasing the film roll, and is stretched in the heating furnace in the advancing direction of the roll, in the direction perpendicular to the advancing direction of the roll, or both. The temperature of the heating furnace is usually in the range from the vicinity of the glass transition temperature of the cyclic polyolefin-based resin to the glass transition temperature + 100 ° C. The magnification of the stretching is usually 1.1 to 6 times, preferably 1.1 to 3.5 times, in one direction.

The surface of the annular polyolefin-based resin film generally has poor surface activity. Therefore, the surface to be bonded to the polarizing film is preferably subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, flame treatment or saponification treatment Do. Of these, plasma treatment and corona treatment, which can be performed relatively easily, are suitable.

As the cellulose acetate based resin film, suitable commercially available products such as Fujit (registered trademark) TD80 (manufactured by Fuji Film), Fujit (registered trademark) TD80UF (manufactured by Fuji Film) (Manufactured by Konica Minolta Opto Co., Ltd.) and KC4UY (manufactured by Konica Minolta Opto Co., Ltd.) are suitably used in combination with a thermosetting resin such as TD80UZ (manufactured by Fuji Photo Film Co., Ltd.), Fujix (registered trademark) TD40UZ Can be used.

A liquid crystal layer or the like may be formed on the surface of the cellulose acetate resin film in order to improve the viewing angle characteristics. Further, in order to impart a retardation, a cellulose acetate-based resin film may be stretched. The cellulose acetate-based resin film is usually subjected to saponification treatment in order to improve adhesion with the polarizing film. As the saponification treatment, a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide can be adopted.

On the surface of the transparent protective film 14 as described above, an optical layer such as a hard coat layer, an antiglare layer, and an antireflection layer may be formed. The method of forming these optical layers on the surface of the transparent protective film is not particularly limited, and a known method can be used.

When the thickness of the transparent protective film 14 is desired to satisfy the requirement for thinning, it is preferably as thin as possible, preferably 88 탆 or less, and more preferably 48 탆 or less. In consideration of workability, it is preferably 5 m or more.

[Polarizer layer]

The polarizer layer 12 may have the same structure as the polarizer layer 12 of the polarizing laminated film 10 described above.

[Pressure sensitive adhesive layer]

The pressure sensitive adhesive to be used for bonding the transparent protective film 14 and the polarizer layer 12 is generally composed of an acrylic resin, a styrene resin, a silicone resin or the like as a base polymer, and an isocyanate compound, an epoxy compound, an aziridine compound And a crosslinking agent is added.

It is also possible to use a pressure-sensitive adhesive layer containing fine particles and exhibiting light scattering properties.

The thickness of the pressure-sensitive adhesive layer is preferably 1 占 퐉 to 40 占 퐉 from the viewpoint of workability and durability. When the thickness of the pressure-sensitive adhesive layer is 3 mu m to 25 mu m, the dimensional change of the polarizing film is also suppressed, which is more preferable.

In the method of bonding the transparent protective film 14 to the polarizer layer 12 by the adhesive agent, the adhesive layer may be formed on the surface of the transparent protective film 14 and then bonded to the polarizer layer 12, ), And then the transparent protective film 14 may be bonded to the adhesive layer.

The method of forming the pressure sensitive adhesive layer is not particularly limited and a solution containing each component including the above base polymer is applied to the surface of the transparent protective film 14 or the surface of the polarizer layer 12, The transparent protective film 14 and the polarizer layer 12 may be bonded to each other and a pressure sensitive adhesive layer may be formed on the separator and transferred to the surface of the transparent protective film 14 or the surface of the polarizer layer 12, Maybe. When the pressure-sensitive adhesive layer is formed on the surface of the transparent protective film 14 or the surface of the polarizer layer 12, the pressure-sensitive adhesive layer may be adhered to the surface of the transparent protective film 14 or the surface of the polarizer layer 12, Treatment, for example, corona treatment may be performed.

[Adhesive layer]

Examples of the adhesive used for bonding the transparent protective film 14 and the polarizer layer 12 include an aqueous adhesive using a polyvinyl alcohol-based resin aqueous solution, a water-based liquid-based urethane emulsion adhesive, or the like. When a cellulose acetate film treated with a saponification treatment such as saponification treatment is used as the transparent protective film 14, a polyvinyl alcohol-based resin aqueous solution is suitably used as an aqueous adhesive for bonding with the polarizer layer 12. The polyvinyl alcohol resin used as the adhesive includes a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate and a vinyl alcohol homopolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith Based copolymers, and further modified polyvinyl alcohol polymers obtained by partially modifying hydroxyl groups thereof. As the water-based adhesive, polyaldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound or the like may be added as an additive. When such an aqueous adhesive is used, the adhesive layer obtained therefrom usually has a thickness of 1 mu m or less, and even if a cross section is observed with an ordinary optical microscope, the adhesive layer is practically not observed.

The method of bonding the polarizer layer 12 to the transparent protective film 14 using an aqueous adhesive is not particularly limited and the adhesive may be uniformly applied to the surface of the polarizer layer 12 and / And a method in which one of the other films is overlaid on the coated surface and joined together by a roll or the like, followed by drying. Usually, the adhesive is applied at a temperature of 15 to 40 占 폚 after its preparation, and the bonding temperature is usually in the range of 15 占 폚 to 30 占 폚.

When an aqueous adhesive is used, the polarizer layer 12 and the transparent protective film 14 are bonded and then dried to remove water contained in the aqueous adhesive. The temperature of the drying furnace is preferably 30 ° C to 90 ° C. If the temperature is lower than 30 DEG C, the adhesive surface between the polarizer layer 12 and the transparent protective film 14 tends to peel off easily. If the temperature is higher than 90 占 폚, the optical performance may deteriorate due to heat. The drying time can be set to 10 seconds to 1000 seconds, and is preferably 60 seconds to 750 seconds, more preferably 150 seconds to 600 seconds from the viewpoint of productivity.

After drying, it may be cured at a room temperature or a slightly higher temperature thereof, for example, at a temperature of about 20 ° C to 45 ° C for about 12 hours to 600 hours. The temperature at the time of curing is generally set lower than the temperature employed at the time of drying.

Further, a photo-curable adhesive may be used as the adhesive when the polarizer layer 12 and the transparent protective film 14 are bonded. Examples of the photo-curable adhesive include a mixture of a photo-curable epoxy resin and a photo cationic polymerization initiator.

Examples of the method of bonding the polarizer layer 12 and the transparent protective film 14 with a photo-curable adhesive include a flexible method (casting method), a Meyer bar coating method, a gravure coating method, a comma coater method, A method in which an adhesive is applied to the adhesive surface of the polarizer layer 12 and / or the transparent protective film 14 by a coating method, a dip coating method, a spraying method, or the like, and both are overlapped. The flexible method is a method in which the polarizer layer 12 or the transparent protective film 14 as an object to be coated is moved in a substantially vertical direction, in a substantially horizontal direction, or in an inclined direction therebetween, Method.

An adhesive is applied to the surface of the polarizer layer 12 or the transparent protective film 14 and then the polarizer layer 12 and the transparent protective film 14 are adhered by being sandwiched between nip rolls or the like through the adhesive application surface. An adhesive is dropped between the polarizer layer 12 and the transparent protective film 14 in a state where the polarizer layer 12 and the transparent protective film 14 are overlapped with each other and then the laminate is pressed with a roll or the like to uniformly The spreading method can also be suitably used. In this case, metal, rubber, or the like can be used as the material of the roll. Further, a method of dropping an adhesive between the polarizer layer 12 and the transparent protective film 14, passing the laminate between rolls, and spreading it by pressurization is preferably adopted. In this case, these rolls may be made of the same material or different materials. The thickness of the adhesive layer after bonding using the nip roll or the like before drying or curing is preferably 0.01 탆 to 5 탆.

A surface treatment such as a plasma treatment, a corona treatment, an ultraviolet irradiation treatment, a flame treatment, or a saponification treatment is suitably applied to the bonding surface of the polarizer layer 12 and / or the transparent protective film 14 May be performed. As the saponification treatment, there may be mentioned a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.

When a photo-curable resin is used as the adhesive, the polarizer layer 12 and the transparent protective film 14 are bonded to each other, and then an active energy ray is irradiated to cure the photo-curable adhesive. A light source of an active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, a low energy mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, A wave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The light irradiation intensity for the photo-curing adhesive is appropriately determined depending on the composition of the photo-curable adhesive and is not particularly limited, but it is preferable that the irradiation intensity in the wavelength range effective for activating the polymerization initiator is 0.1 to 6000 mW / cm2. When the irradiation intensity is 0.1 mW / cm < 2 > or more, the reaction time is not excessively long, and when the irradiation intensity is 6000 mW / cm < 2 > or less, the heat radiated from the light source and heat generated during curing of the photocurable adhesive deteriorate the yellowing of the epoxy resin, Is less likely to occur. The light irradiation time for the photo-curable adhesive is applied according to the photo-curing adhesive to be cured and is not particularly limited, but it is set so that the integrated light quantity represented by the product of the irradiation intensity and the irradiation time is 10 to 10000 mJ / desirable. When the total amount of light for the photo-curable adhesive is 10 mJ / cm 2 or more, a sufficient amount of active species derived from the polymerization initiator can be generated sufficiently to allow the curing reaction to proceed more surely. When the amount is less than 10000 mJ / cm 2, So that good productivity can be maintained. On the other hand, the thickness of the adhesive layer after irradiation with active energy rays is usually about 0.001 to 5 탆, preferably 0.01 to 2 탆, more preferably 0.01 to 1 탆.

When the photo-curing adhesive is cured by irradiation of an active energy ray, the curing is performed under such a condition that the polarizing plate 12 is not deteriorated in various functions of the polarizing plate, such as the polarization degree, transmittance and hue, and transparency of the transparent protective film 14 .

[Other optical layers]

The polarizing plate of the present invention produced as described above can be used as a polarizing plate in which other optical layers are laminated in practical use. Further, the transparent protective film 14 may have the function of these optical layers. Examples of other optical layers include a reflection type polarizing film that transmits polarized light of any kind and reflects polarized light exhibiting properties opposite thereto, a film having an antireflection function having a concavo-convex shape on the surface, A film, a reflection film having a reflection function on the surface, a transflective film having a reflection function and a transmission function, and a viewing angle compensation film.

For example, DBEF (available from 3M, available from Sumitomo 3M Ltd.), APF (available from Sumitomo 3M Co., Ltd.), and the like, which correspond to a reflection type polarizing film that transmits polarized light of a certain kind, (Available from 3M, available from Sumitomo 3M Co., Ltd.). Examples of the viewing angle compensation film include an optical compensation film coated with a liquid crystalline compound on the surface of the substrate and an oriented phase difference film made of a polycarbonate based resin and a retardation film made of a cyclic polyolefin based resin. As a commercially available product corresponding to the optical compensation film on which the liquid crystal compound is applied to the surface of the substrate and to which the liquid crystal compound is applied, a WV film (manufactured by Fuji Film), an NH film (manufactured by Shin-Nippon Sekiyu Co., Ltd.) (Manufactured by Nippon Sekiyu Co., Ltd.). Examples of commercially available products corresponding to the retardation film made of a cyclic polyolefin resin include Aton (registered trademark) film (manufactured by JSR Corporation), Escina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.) (Registered trademark) film (manufactured by Optesis Co., Ltd.).

≪ Method for producing a polarizing laminated film &

Fig. 3 is a flow chart showing an embodiment of a method for producing the polarizing laminated film 10 shown in Fig. According to this, the method for producing the polarizing laminated film 10 is a method for producing a laminated film by forming a polyvinyl alcohol-based resin layer having a saponification degree of not more than 99.0 mol% on one surface of a base film 11, A resin layer forming step (S10), a stretching step (S20) of forming a stretched film by subjecting the laminated film to a uniaxial stretching process at a stretching magnification of more than 5 times, a step of dyeing the resin layer with a dichroic dye to form a polarizer layer 12 (Step S30) of obtaining a polarizing laminated film 10 as a film forming step (step S30).

The polarizing laminated film 10 obtained by this manufacturing method is a polarizing laminated film 10 provided with a polarizer layer 12 having a thickness of 10 μm or less on a stretched base film 11. This may be used as the polarizing plate as it is or as an intermediate product for transferring the polarizing layer 12 to the transparent protective film as described later.

The visible light transmittance corrected by the polarizer is usually 40% or more, and the visibility correction polarized light Py is usually 99.9% or more. Preferably, Ty is 41.0% or more, and Py is 99.9% or more. More preferably, Ty is 42.5% or more, and Py is 99.9% or more.

Visible Sensitivity Correction Value of Polarizer The transmittance (Ty) and visibility sensitivity correction polarization degree (Py) are measured by a spectrophotometer (V7100, manufactured by Nihon Bunko Co., Ltd.) having an integral sphere. The MD transmittance and the TD transmittance are determined in the wavelength range of 380 nm to 780 nm and the simple transmittance and the degree of polarization at each wavelength are calculated based on the expressions (1) and (2) C light source) to obtain the visual sensitivity-corrected single unit light transmittance Ty and the visual sensitivity correction polarity Py. Here, the "MD transmittance" is the transmittance when the polarizing direction of the polarizing plate sample is made parallel to the direction of the polarized light emerging from the Glan Thompson prism, and is represented by "MD" in the formulas (1) and (2). The term " TD transmittance " is the transmittance when the direction of the polarization of light emerging from the Glan Thompson prism and the transmission axis of the polarizing plate sample are orthogonal, and is represented by " TD " in formulas (1) and (2).

Bulk transmittance (%) = (MD + TD) / 2 Equation (1)

(%) = {(MD-TD) / (MD + TD)} 1/2 占 100 Equation (2)

≪ Polarizing plate production method >

4 is a flowchart showing an embodiment of a manufacturing method of the polarizing plate 13 shown in Fig. According to the method, the method for producing the polarizing plate 13 includes a resin layer forming step of forming a resin layer made of a vacuum-degassed polyvinyl alcohol-based resin having a saponification degree of 99.0 mol% or less on one surface of a base film to form a laminated film (S10), a stretching step (S20) of subjecting the laminated film to a stretched film by a uniaxial stretching process at a stretching magnification of more than 5 times, dyeing to obtain a polarizing laminated film as a polarizing layer 12 After the step S30 is performed in this order, a transparent protective film 14 is bonded to a surface of the polarizing layer 12 of the polarizing laminated film opposite to the surface on the base film 11 side to obtain a multilayered film A bonding step (S40), and a peeling step (S50) of peeling the base film (11) from the multilayer film in this order.

The polarizing plate 13 obtained by this manufacturing method is a polarizing plate 13 having a polarizing layer 12 with a thickness of 10 m or less on the transparent protective film 14. [ The polarizing plate 13 can be used, for example, by bonding to another optical film or a liquid crystal cell through a pressure sensitive adhesive.

Hereinafter, each step of S40 to S50 in Fig. 4 will be described in detail. On the other hand, the respective steps of S10 to S30 of Fig. 4 are the same as the steps of S10 to S30 of Fig.

[Bonding step (S40)]

Here, a transparent protective film is bonded to a surface of the polarizer layer opposite to the surface on the base film side to obtain a multilayer film. As a method of bonding the transparent protective film, there are a method of bonding the polarizer layer 12 and the transparent protective film 14 with a pressure-sensitive adhesive, and a method of bonding the polarizer layer 12 surface and the transparent protective film 14 with an adhesive have. Materials suitable as the transparent protective film are as described in the description of the constitution of the polarizing plate. A preferable method of bonding the polarizer layer 12 and the transparent protective film 14 by using an adhesive suitable for use, a material of the pressure-sensitive adhesive, and the polarizer layer 12 is as described in the description of the constitution of the polarizer.

[Peeling step (S50)]

In the polarizing plate manufacturing method of the present embodiment, as shown in Fig. 4, a peeling step (S50) of the base film is performed after the bonding step (S40) of bonding the transparent protective film to the polarizer layer 12. In the peeling step (S50) of the base film, the base film is peeled from the multi-layer film. The method of peeling off the base film is not particularly limited, and can be peeled off in the same manner as the peeling film of the polarizing plate having a usual pressure-sensitive adhesive. After the step of bonding the transparent protective film (S40), the film may be peeled off as it is, or may be peeled off by forming a roll once, followed by peeling step separately.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

[Example]

≪ Example 1 >

(1) Production of base film

(Trade name: SUMITOMONOBLEN W151, manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 138 DEG C) containing about 5% by weight of an ethylene unit and a propylene / ethylene random copolymer Layer structure having a resin layer composed of a polymer (" Sumitomonoblen FLX80E4 " manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 163 DEG C) was placed in a coextrusion molding machine using a multilayer extrusion molding machine Lt; / RTI > The total thickness of the base film was 100 占 퐉, and the thickness ratio (FLX80E4 / W151 / FLX80E4) of each layer was 3/4/3.

(2) Preparation of coating liquid

Polyvinyl alcohol powder ("Z-200" manufactured by Nippon Gosei Chemical Industry Co., Ltd., average polymerization degree: 1100, average saponification degree: 99.5 mol%) was dissolved in hot water at 95 ° C, and a polyvinyl alcohol aqueous solution Was prepared. The obtained aqueous solution was mixed with 1 part by weight of a crosslinking agent ("Sumirez Resin 650" manufactured by Daoka Kagaku Kogyo Co., Ltd.) per 2 parts by weight of the polyvinyl alcohol powder to obtain a coating solution for forming a primer layer.

The resulting primer layer-forming coating solution was transferred to a stainless steel container of 30 L (liter) and transferred to a coating facility.

Further, a polyvinyl alcohol powder ("PVA 124" manufactured by Kuraray Co., Ltd., average degree of polymerization: 2400, average degree of saponification: 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 8% And this was used as a coating solution for forming a polyvinyl alcohol-based resin layer.

The resulting coating solution for forming a polyvinyl alcohol-based resin layer was transferred into a 30 L stainless steel container and transferred to a coating facility.

(3) Conduct of vacuum degassing

The coating solution for forming a polyvinyl alcohol-based resin layer prepared in (2) was placed in a processing container and treated at -0.04 MPa (gauge pressure) for 120 minutes. At this time, the container continued to be inspired. The liquid temperature after the defoaming treatment was 26.0 DEG C and used for coating without heating and cooling.

(4) Formation of primer layer and polyvinyl alcohol-based resin layer

The substrate film produced in the above (1) was continuously conveyed, corona treatment was performed on one side thereof, and the coating solution for forming a primer layer prepared in the above (2) was applied to the corona-treated surface using a micro gravure coater Followed by drying at 60 캜 for 3 minutes to form a primer layer having a thickness of 0.2 탆. Subsequently, while the film was being conveyed, the above-mentioned coating liquid was continuously coated on the primer layer using the comma coater filled with the coating liquid for polyvinyl alcohol-based resin layer up to the coating head, Followed by drying at 70 캜 for 3 minutes and subsequently at 60 캜 for 4 minutes to form a polyvinyl alcohol resin layer having a thickness of 11.0 탆 on the primer layer.

The base film side opposite to the side on which the polyvinyl alcohol resin layer was formed was subjected to the same treatment as described above to sequentially form a primer layer and a polyvinyl alcohol resin layer, And a polyvinyl alcohol-based resin layer having a thickness of 11.0 占 퐉 were formed to obtain a laminated film composed of a polyvinyl alcohol-based resin layer / primer layer / base film / primer layer / polyvinyl alcohol-based resin layer.

(5) Stretching of laminated film

The laminated film obtained in the above (4) was subjected to free-end uniaxial stretching at a draw ratio of 5.5 times in the machine direction (film transport direction) at a draw temperature of 160 DEG C by a nip roll interlining method while continuously conveying it to form a stretched film. The thickness of the polyvinyl alcohol-based resin layer in the stretched film was 5.5 m on one side and 5.9 m on the other side.

(6) Production of polarizing laminated film

After the stretched film prepared in the above (5) was continuously conveyed, it was dipped in a hot water bath at 60 ° C for 60 seconds, and then dipped in a dyeing solution at 30 ° C containing iodine and potassium iodide for about 150 seconds So as to dye the polyvinyl alcohol-based resin layer, and then the excess dyeing solution was washed away with pure water at 10 占 폚. Subsequently, the substrate was immersed in a crosslinked solution at 76 DEG C containing boric acid and potassium iodide so that the residence time would be 600 seconds, and crosslinking treatment was carried out. Thereafter, the film was washed with pure water at 10 占 폚 for 4 seconds and dried at 80 占 폚 for 300 seconds to prepare a polarizing laminated film.

In the obtained polarizing laminated film, the thicknesses of the polarizers laminated on both surfaces of the substrate were 5.8 μm and 6.0 μm, respectively.

(7) Pore observation with a length of 100 탆 or more

The polarizing layer having a thickness of 6.0 占 퐉 was peeled off from the obtained polarizing laminated film to prepare a single-side laminated film comprising a base film and a polarizer layer having a thickness of 5.8 占 퐉.

The obtained single-sided laminated film was cut into a size of 300 mm in the direction of the absorption axis and 200 mm in the direction perpendicular to the absorption axis, and visually observed with a magnifying glass having a scale of 10 times magnification on the plane light source. A total of 20 sheets (1.2 m 2) were found. As a result, the number of pores having a length in the direction of the absorption axis of 100 탆 or more was 8, and the number per unit area was 6.7 pcs / m 2.

The MD transmittance and the TD transmittance in the wavelength range of 380 nm to 780 nm of the obtained single-sided laminated film (single-side laminated film composed of the base film and the polarizer layer having a thickness of 5.8 mu m) were measured with a spectrophotometer (Nihon Bunko Co., (V7100), and the simple transmittance and the degree of polarization at each wavelength are calculated on the basis of the above equations (1) and (2), and the visual sensitivity correction is carried out by the second view field (C light source) of JIS Z 8701 The visibility-corrected corrected single-beam transmittance Ty and visibility-correction corrected polarization degree Py were found to be Ty: 42.9% and Py: 99.92%.

(8) Production of Polarizing Plate

A polyvinyl alcohol aqueous solution having a concentration of 3% by weight was prepared by dissolving polyvinyl alcohol powder ("KL-318" manufactured by Kuraray Co., Ltd., average degree of polymerization: 1800) in hot water at 95 ° C. The obtained aqueous solution was mixed with 1 part by weight of a crosslinking agent (" Sumirez Resin 650 ", manufactured by Daoka Kagaku Kogyo Co., Ltd.) per 2 parts by weight of the polyvinyl alcohol powder to obtain an adhesive aqueous solution.

Next, a transparent protective film (triacetylcellulose (TAC (polyvinylidene fluoride), polyvinylidene fluoride (PVA), polyvinylidene fluoride (KC4UY, manufactured by Konica Minolta Opto, Inc.) having a thickness of 40 占 퐉) was bonded on the polarizing layer and passed between a pair of bonding rolls to press the TAC / polarizer layer / primer Layer / substrate film / primer layer / polarizer layer / TAC layer.

Subsequently, the bonding film was peeled off at the interface between the base film and the primer layer, and a film composed of a TAC / polarizer layer (5.8 mu m) / primer layer / base film and a primer layer / polarizer layer (6.0 mu m) / TAC After obtaining a polarizing plate, the base film was peeled off from the former film to obtain another polarizing plate. In the step of peeling the base film, no problem such as breakage of the film occurred.

(8) Pressure-sensitive adhesive layer laminating process

The surface of the obtained polarizer layer on the side of the primer layer of the polarizer having a thickness of 5.8 mu m was subjected to corona treatment and a sheet-like pressure sensitive adhesive laminated with a 25 mu m thick acrylic pressure sensitive adhesive on the PET film (separator film) Polarizer layer / separator film / pressure-sensitive adhesive / primer layer / polarizer layer / TAC ".

(9) Preparation of sample for evaluation

The polarizing plate having the obtained pressure-sensitive adhesive was cut into a size of 60 mm x 60 mm so that the absorption axis was 0 DEG with respect to the sides, and the separator film was peeled off to adhere the adhesive surface to the glass. This was used as an evaluation sample.

(10) Thermal shock test (HS test)

24 evaluation samples were placed in a test bath and the cycle of 30 minutes at -40 DEG C for 30 minutes and 85 DEG C for 30 minutes was repeated 400 times, and cracks were generated in the direction of the absorption axis of the polarizer.

(11) Pore observation in cracks

As a result of observing the generated cracks through the use of an optical microscope (VHX-500, manufactured by GUENNES CO., LTD.), It was found that in the cracks generated, the cracks were observed in the direction of the absorption axis It was observed that it had minute voids of less than 100 mu m. The minute pores had a very small thickness in the thickness direction of less than the thickness of the polarizer and were buried in the polarizer layer, unlike the voids due to bubbles. For this reason, it is difficult to detect and observe such minute bubbles normally by naked eyes or microscopes, but as described above, the bubbles are observed in the cracks, and it seems that they are a cause of cracks.

The size of the minute voids was less than 100 占 퐉 in the direction of the absorption axis, and the center of the minute voids was cut perpendicularly to the absorption axis direction and the length in the thickness direction was about 3 占 퐉.

≪ Example 2 >

A sample was prepared and evaluated in the same manner as in Example 1 except that the gauge pressure of the pressure reduction treatment in (3) in Example 1 was set to -0.09 MPa. The liquid temperature after the treatment was 24.7 占 폚. The obtained defoaming liquid was used for coating without performing operations such as heating and cooling.

The thickness of the evaluated polarizer layer was 5.2 탆. As a result of confirming the pores having a length of 100 mu m or more in the direction of the absorption axis with respect to the sample produced from the single-sided laminated film, the number of pores was one and the number of pores per unit area was 0.83 pores / m 2.

Among the cracks generated in the HS test, the above-mentioned minute voids were observed in the cracks.

The visibility-corrected single-unit transmittance Ty and visibility-sensitivity-corrected polarization degree Py of this single-sided laminated film were Ty: 42.5% and Py: 99.93%, respectively.

≪ Comparative Example 1 &

A polarizing laminated film was produced in the same manner as in Example 1 except that the vacuum degassing treatment of (3) was not carried out. As a result, the thickness of the polarizer layer on one side was 5.8 mu m and the thickness of the polarizer layer on the other side was 5.1 mu m Respectively.

At this time, 44 pores / m 2 of pores having a length of 100 μm or more in the longitudinal direction were observed on the surface of 5.8 μm in thickness.

An evaluation sample was prepared and evaluated in the same manner as in Example 1 on the surface having a thickness of 5.8 占 퐉. As a result, it was found that a minute void appeared as a cause of cracking in the crack in the crack generated by the thermal shock test (HS test) There were 14.

Pore: Number of pores having a length of 100 mu m or more in the direction of the absorption axis (pore / m 2)

Thermal shock test: Number of cracks in which minute voids less than 100 탆 were observed in the direction of the absorption axis in the crack (number)

According to the production method of the present invention, it is possible to produce a polarizer having a reduced bubble defect and a reduced risk of cracking, and a polarizing laminate comprising the polarizer and a polarizer. Even if a polarizing plate including such a polarizer is provided in a thermal shock test in consideration of a change in temperature at the time of incorporation into a liquid crystal display apparatus, the polarizer can not be easily cracked due to voids originating from microbubbles remaining in the polyvinyl alcohol- .

10: Polishing laminated film 11: Base film
12: Polarizer layer 13: Polarizing plate
14: Transparent protective film

Claims (8)

Wherein the pores having a length in the direction of the absorption axis of 100 m or more are 10 pts / m < 2 > or less. The polarizer according to claim 1, wherein the thickness of the polarizer is 10 占 퐉 or less. A polarizing laminated film according to any one of claims 1 to 3, wherein the polarizer is formed on at least one side of the base film. A polarizing plate in which a transparent protective film is laminated on at least one surface of the polarizer according to any one of claims 1 to 3. A method for producing a polarizing laminated film in which a polarizer layer made of a polyvinyl alcohol resin is formed on at least one surface of a base film and the number of pores having a length in the absorption axis direction of 100 m or more is 10 /
A method for producing a laminated film, comprising the steps of: applying an aqueous solution of a polyvinyl alcohol-based resin under reduced pressure to at least one surface of a base film to obtain a laminated film having a resin layer comprising a polyvinyl alcohol-
A step of stretching the laminated film to obtain a stretched film,
And dyeing the resin layer of the stretched film with a dichroic dye to form a polarizer layer
A method for producing a polarizing laminated film. The method for producing a polarizing laminated film according to claim 5, wherein the thickness of the polarizer layer made of a polyvinyl alcohol-based resin is 10 占 퐉 or less. The method for producing a polarizing laminated film according to claim 5 or 6, wherein the aqueous solution of the polyvinyl alcohol-based resin subjected to vacuum degassing is an aqueous solution of a polyvinyl alcohol-based resin obtained by defoaming by reducing the pressure to -0.04 MPa (gauge pressure) Way. A bonding process for bonding a transparent protective film to a surface of a polarizing layer of a polarizing layer according to any one of claims 5 to 7 opposite to a base film side to obtain a multilayer film,
And peeling the base film from the multi-layer film.

Images