KR101420584B1 - Method for producing polarizing laminated film and double-sided polarizing laminated film - Google Patents

Abstract

The present invention relates to a method of producing a double-side polarizing laminated film comprising a base film and a polarizer layer formed on both sides of the base film, wherein a polyvinyl alcohol resin layer is formed on both sides of the base film to obtain a double- The method for producing a polarizing plate according to any one of claims 1 to 3, wherein the polyvinyl alcohol-based resin layer on both sides of the stretched double-side laminated film is dyed with a dichroic dye and subjected to a crosslinking treatment, And a dyeing step of forming a double-sided polarizing laminated film in this order. According to the present invention, it is possible to suppress curling of a film which occurs in a process of producing a polarizing plate which is thin and has high polarization performance, for example, in a drawing process, a drying process after dyeing, or a storage of a drawn film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing a polarizing laminated film, and a method for producing a polarizing laminated film,

The present invention relates to a polarizing laminated film, a polarizing plate or a method for producing a polarizing plate with a base film attached thereto, and a double-side laminated film, a double-side polarizing laminated film, a double-side bonded film and a single-side bonded film.

BACKGROUND ART A polarizing plate has been widely used as a polarizing light supply element or the like in a display device such as a liquid crystal display device. As such a polarizing plate, a polarizing film (polarizer layer) made of a polyvinyl alcohol-based resin has been conventionally adhered with a protective film made of triacetylcellulose. Recently, a polarizing plate having a polarizing plate It is required to be thin and lightweight in accordance with the development of the device.

Conventionally, a polarizing plate is produced by preparing a polarizing film by performing a dyeing treatment or a crosslinking treatment while stretching or stretching a film made of a polyvinyl alcohol-based resin alone, and then laminating it on a protective film or the like. To the limit of thickness. Therefore, after a polyvinyl alcohol-based resin layer of a polarizer layer is formed on the surface of the base film, a polyvinyl alcohol-based resin layer is stretched for each base film, and after a dyeing / crosslinking step and a subsequent drying step, a polyvinyl alcohol- A method is known in which the total thickness of the base film and the polarizer layer can be reduced to a limit and the thickness of the polarizer layer (polarizing film) can be made thinner than the conventional one by using the resin layer as a polarizer layer (for example, JP 2000-338329- A).

However, in the method described in JP2000-338329-A, in the drying step immediately after the crosslinking step, the crosslinking reaction remarkably progressed, and the polyvinyl alcohol-based resin layer shrinks in the width direction of the film in some cases. In this case, if the film is to be continuously produced, only the polyvinyl alcohol-based resin layer of the laminated film composed of the base film and the polyvinyl alcohol-based resin layer shrinks in the width direction and the end portion of the polyvinyl alcohol- There has been a problem that it is in a collapsed state. Further, when the laminated film after stretching is left standing, there is a problem that the polyvinyl alcohol-based resin layer on one side is absorbed and stretched to cause curling of the film.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a polarizing plate which is thin and has high polarization performance, suppresses curling of the film caused by a stretching process, a drying process after dyeing, .

That is, the present invention includes the following.

[1] A method for producing a double-side polarizing laminated film comprising a base film and a polarizer layer formed on both sides of the base film,

A resin layer forming step of forming a polyvinyl alcohol resin layer on both surfaces of the base film to obtain a double-side laminated film,

A stretching step of stretching the double-side laminated film,

Wherein the polyvinyl alcohol resin layer on both sides of the stretched double-side laminated film is dyed with a dichroic dye, and a cross-linking treatment is performed to form a polarizer layer by a double-side polarizing laminated film ≪ / RTI >

[2] The production method according to [1], wherein the material constituting the polyvinyl alcohol-based resin layer on both sides of the double-side laminated film is the same material.

[3] The production method according to [1] or [2], wherein the difference in thickness of the polyvinyl alcohol-based resin layer on both surfaces of the double-side laminated film after stretching is 3 m or less.

[4] The production method according to any one of [1] to [3], wherein the stretching step is performed at a stretching ratio of more than 5 times.

[5] The production method according to any one of [1] to [4], wherein the thickness of each of the polarizer layers on both surfaces of the double-side polarizing laminated film is 10 μm or less.

[6] A method for producing a polarizing plate comprising a polarizer layer and a protective film formed on one side of the polarizer layer,

A protective film bonding step of bonding a protective film to both surfaces of a double-sided polarizing laminated film obtained by the method described in [1] to obtain a double-sided bonded film;

And a peeling step of peeling off at least one polarizing plate from the double-side bonded film in this order.

[7] The production method according to [6], wherein the two polarizing plates on both sides of the double-side bonded film are peeled simultaneously in the peeling step.

[8] The production method according to [6], wherein in the peeling step, the polarizing plate on one side of the double-side bonded film is peeled off, and then the polarizing plate on the other side is peeled off.

[9] A method for producing a polarizing plate having a polarizer layer, a protective film formed on one side of the polarizer layer, and a base film bonded to one side of the polarizer layer,

A protective film bonding step of bonding a protective film to both surfaces of a double-sided polarizing laminated film obtained by the method described in [1] to obtain a double-sided bonded film;

And a peeling step of peeling the polarizing plate having the base film from the double-side bonded film in this order.

[10] A method for producing a polarizing plate comprising a polarizer layer and a protective film formed on one side of the polarizer layer,

A protective film bonding step of bonding a protective film to one surface of the double-sided polarizing laminated film obtained by the method described in [1] to obtain a single-

And a peeling step of peeling the polarizing plate from the one-side bonded film in this order.

[11] A method for producing a single-sided polarizing laminated film comprising a base film and a polarizer layer formed on one side of the base film,

A protective film bonding step of bonding a protective film to one surface of the double-sided polarizing laminated film obtained by the method described in [1] to obtain a single-

And a peeling step of peeling the single-sided polarizing laminated film from the single-sided laminated film in this order.

[12] A double-side laminated film comprising a base film and a polyvinyl alcohol-based resin layer formed on both sides of the base film.

[13] A double-side laminated film comprising a base film and a polyvinyl alcohol-based resin layer formed on both sides of the base film and oriented.

[14] A double-sided polarizing laminated film comprising a base film and a polyvinyl alcohol-based resin layer formed on both sides of the base film and oriented and adsorbing a dichroic dye.

[15] A double-sided polarizing laminated film comprising a base film and a polarizer layer formed on both sides of the base film, and a protective film bonded to both surfaces of the double-side polarizing laminated film.

[16] A one-side polarizing laminated film comprising a base film and a polarizer layer formed on both sides of the base film, and a protective film bonded to one side of the two-side polarizing laminated film.

In the present invention, since the polyvinyl alcohol resin layer is formed on both surfaces of the base film and the processes such as drawing, dyeing, and drying are performed, curling of the film generated in the production process of the polarizing plate and the like can be suppressed And stable production is possible.

Further, in the stretching step, the dyeing step and the bonding step, the polyvinyl alcohol-based resin layer (double-sided) having a double area can be processed at one time, and the production efficiency of the polarizing plate is improved. In addition, it is not necessary to use a special drying furnace at the time of drying in each production step, and it is possible to reduce the cost in the facility.

Fig. 1 is a flowchart showing an outline of a method for producing a polarizing plate of the present invention.
Fig. 2 is a flowchart for explaining a method of producing a double-side polarizing laminated film of Example 1 and a method of producing a polarizing plate of Example 2;
3 is a flow chart for explaining the method for producing the polarizing plate of Example 3. Fig.

In this specification, a laminate having a polyvinyl alcohol resin layer (a layer composed of a polyvinyl alcohol resin) on one side of a base film is referred to as a " one side laminated film ", and a polyvinyl alcohol Laminated body having a base resin layer is referred to as " double-side laminated film ".

A laminate having a polarizer layer on one side of a base film is referred to as a " one-side polarizing laminated film ", and a laminate having a polarizer layer on one side of the base film is referred to as a " Laminated film having a polarizer layer is referred to as " double-side polarizing laminated film ". The laminate having a protective film on one side of the polarizer layer is referred to as a " polarizer ".

Hereinafter, each component will be described in detail.

[Base film]

As the resin used for the base film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, and stretchability is used, and a suitable resin can be selected according to the Tg or Tm. Specific examples of the thermoplastic resin include a polyolefin resin, a polyester resin, a cyclic polyolefin resin (norbornene resin), a (meth) acrylic resin, a cellulose ester resin, a polycarbonate resin, a polyvinyl alcohol resin, Based resin, a polyarylate-based resin, a polystyrene-based resin, a polyethersulfone-based resin, a polysulfone-based resin, a polyamide-based resin, a polyimide-based resin and a mixture or copolymer thereof.

The base film may be a film made of only one kind of the above-mentioned resin, or may be a film formed by blending two or more kinds of resins. The base film may be a single layer film or a multilayer film.

Examples of the polyolefin-based resin include polyethylene and polypropylene, which are preferable because they can be stably drawn at a high magnification. An ethylene-polypropylene copolymer obtained by copolymerizing propylene with ethylene may also be used. Other types of monomers may be copolymerized, and other types of monomers copolymerizable with propylene include ethylene and alpha -olefin. As the? -olefin, an? -olefin having 4 or more carbon atoms is preferably used, and more preferably an? -olefin having 4 to 10 carbon atoms. Specific examples of the? -Olefin having 4 to 10 carbon atoms include linear monoolefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-decene; Branched monoolefins such as 3-methyl-1-butene, 3-methyl-1-pentene and 4-methyl-1-pentene; Vinyl cyclohexane and the like. The copolymer of propylene and other monomer copolymerizable therewith may be a random copolymer or a block copolymer. The content of the constituent units derived from the other monomers in the copolymer can be determined by carrying out infrared (IR) spectrum measurement according to the method described on page 616 of "Polymer Analysis Handbook" (published by Kinokuniya Shoten in 1995) .

Above all, propylene homopolymer, propylene-ethylene random copolymer, propylene-1-butene random copolymer and propylene-ethylene-1-butene random copolymer are preferably used as the propylene resin constituting the propylene resin film do.

The stereoregularity of the propylene resin constituting the propylene-based resin film is preferably substantially isotactic or syndiotactic. A propylene resin film made of a propylene resin having substantially isotactic or syndiotactic stereoregularity is relatively easy to handle and has excellent mechanical strength under a high temperature environment.

The polyester-based resin is a polymer having an ester bond, and is mainly a polycondensation product of a polycarboxylic acid and a polyhydric alcohol. The polyvalent carboxylic acid to be used is mainly a divalent dicarboxylic acid, and examples thereof include isophthalic acid, terephthalic acid, dimethyl terephthalate, dimethyl naphthalenedicarboxylate, and the like. Also, polyhydric alcohols to be used mainly include divalent diols, and examples thereof include propanediol, butanediol, neopentyl glycol, cyclohexanedimethanol, and the like. Specific examples of the resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, and polycyclohexanedimethanol naphthalate. . These blend resins and copolymers can also be suitably used.

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 that is polymerized using a cyclic olefin as a polymerization unit, and examples thereof include resins described in JPH01-240517-A, JPH03-14882-A, JPH03-122137-A, 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 derivatives , Graft polymers obtained by modifying graft polymers, and hydrides thereof. Specific examples of cyclic olefins include norbornene 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).

Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate is exemplified. As the (meth) acrylic resin, a methyl methacrylate resin having a main component (50 to 100 wt%, preferably 70 to 100 wt%) of methyl methacrylate is used.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate.

These copolymers and those obtained by modifying a part of the hydroxyl groups with other kinds of substituents or the like are also cited. Of these, cellulose triacetate is particularly preferable. Most of the products of cellulose triacetate are commercially available and are advantageous in terms of availability and cost. Examples of commercially available products of cellulose triacetate include Fujisac (registered trademark) TD80 (manufactured by Fuji Film Co., Ltd.), Fujisak (registered trademark) TD80UF (manufactured by Fuji Film) (Manufactured by Konica Minolta Opt.), KC4UY (manufactured by Konica Minolta Opt.), And the like can be given.

The polycarbonate resin is an engineering plastic made of a polymer having a monomer unit bonded through a carbonate group, and is a resin having high impact resistance, heat resistance and flame retardancy. Further, since it has high transparency, it is suitably used for optical use. For optical use, a resin called a modified polycarbonate such as a modified polymer skeleton for lowering the photoelastic coefficient and a copolymerized polycarbonate improved in wavelength dependency are commercially available and can be suitably used. Such a polycarbonate resin is widely available and is commercially available from, for example, Panlite (trade name), manufactured by TIJIN KASEI CO., LTD., Yupiron (registered trademark), Mitsubishi Engineering Plastics Co., Sumitomo Dow Co., Ltd. and Caliber 占 (Dow Chemical Co., Ltd.).

In addition to the above-mentioned thermoplastic resin, any appropriate additives may be added to the base film. Examples of such an additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release 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 before stretching can be appropriately determined, but it is generally from 1 탆 to 500 탆, more preferably from 1 탆 to 300 탆, still more preferably from 1 탆 to 300 탆, from the viewpoint of workability such as strength and handling properties, Is 5 mu m to 200 mu m, and most preferably 5 mu m to 150 mu m.

The base film may be subjected to a corona treatment, a plasma treatment, a flame treatment, or the like on at least a surface of the polyvinyl alcohol-based resin layer on which the polyvinyl alcohol-based resin layer is to be formed, in order to improve adhesion with the polyvinyl alcohol-based resin layer. In order to improve the adhesion, a thin layer such as a primer layer or an adhesive layer may be formed on the surface of the base film on which the polyvinyl alcohol-based resin layer is formed.

(Primer layer)

When the primer layer is formed on the surface of the base film on which the polarizer layer is to be formed, the primer layer is not particularly limited as long as it is a material exhibiting a strong adhesion to the base film and the polyvinyl alcohol-based resin layer to some extent. For example, a thermoplastic resin excellent in transparency, thermal stability, stretchability and the like is used. Specific examples include acrylic resins and polyvinyl alcohol resins, but are not limited thereto. Among them, a polyvinyl alcohol-based resin having good adhesion is preferably used.

Examples of the polyvinyl alcohol-based resin used as the primer layer include a polyvinyl alcohol resin and derivatives thereof. Examples of derivatives of the polyvinyl alcohol resin include polyvinyl formal, polyvinyl acetal, and the like. The polyvinyl alcohol resin may be mixed with an unsaturated carboxylic acid such as olefin such as ethylene or propylene, acrylic acid, methacrylic acid, crotonic acid, Or an alkyl ester, acrylamide, or the like. Of the above-mentioned polyvinyl alcohol-based resin materials, polyvinyl alcohol resins are preferably used.

To increase the strength of the primer layer, a crosslinking agent may be added to the thermoplastic resin. As the crosslinking agent to be added to the thermoplastic resin, known ones such as an organic type and an inorganic type can be used. A more suitable one may be appropriately selected for the thermoplastic resin to be used. For example, high molecular weight crosslinking agents such as methylol melamine resins and polyamide epoxy resins can be used in addition to low molecular weight crosslinking agents such as epoxy crosslinking agents, isocyanate crosslinking agents, dialdehyde crosslinking agents and metal chelating crosslinking agents. When a polyvinyl alcohol resin is used as the thermoplastic resin, it is particularly preferable to use a polyamide epoxy resin, methylol melamine, dialdehyde, metal chelate crosslinking agent, or the like as the crosslinking agent.

The thickness of the primer layer is preferably 0.05 탆 to 1 탆, and more preferably 0.1 탆 to 0.4 탆. If it is too thin, adhesion between the base film and the polyvinyl alcohol layer is deteriorated, and if it is too thick, the polarizing plate becomes thick.

[Polarizer layer]

Specifically, the polarizer layer is formed by adsorbing and orienting a dichroic dye on a stretched polyvinyl alcohol-based resin layer.

As the polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin layer, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include a copolymer of vinyl acetate and other monomers copolymerizable with vinyl acetate, as well as polyvinyl acetate, which is a homopolymer of vinyl acetate. 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 polyvinyl alcohol-based resin constituting the polarizer layer (polyvinyl alcohol-based resin layer) is preferably a completely saponified product. The degree of saponification is preferably from 80 mol% to 100 mol%, more preferably from 90 mol% to 99.5 mol%, and most preferably from 94 mol% to 99 mol%.

When the degree of saponification is less than 80 mol%, there is a problem that the water resistance and moisture resistance after heat treatment are poor. When a polyvinyl alcohol-based resin having a saponification degree of more than 99.5 mol% is used, the dyeing speed is slowed, and a time several times as long as usual may be required to obtain a polarizing laminated film having sufficient polarization performance.

The saponification degree referred to herein is a numerical value defined by the following formula, in which the unit ratio (mol%) of the acetic acid group contained in the polyvinyl alcohol-based resin as the raw material of the polyvinyl alcohol-based resin is changed to the hydroxyl group by the saponification process. It can be obtained by a method defined 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 resin used in the present invention may be a modified polyvinyl alcohol partially modified. Examples thereof include those obtained by modifying a polyvinyl alcohol resin with an olefin such as ethylene or propylene, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, an alkyl ester of an unsaturated carboxylic acid, or an acrylamide . The ratio of denaturation is preferably less than 30 mol%, more preferably less than 10%. When the modification is performed in an amount exceeding 30 mol%, it is difficult to adsorb the dichroic dye and the polarization performance may be lowered.

The average degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, but is preferably 100 to 10,000, more preferably 1,500 to 8,000, and most preferably 2,000 to 5,000. The average degree of polymerization as used herein is also a value obtained by a method determined by JIS K 6726 (1994).

Examples of polyvinyl alcohol resins having such properties include PVA124 (saponification degree: 98.0 to 99.0 mol%), PVA117 (saponification degree: 98.0 to 99.0 mol%), PVA624 (saponification degree: 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 Nihon Seika Kagaku Kogyo Co., ) And N-300 (saponification degree: 98.0 to 99.0 mol%); For example, JAPAN VAM & POVAL CO. (Saponification degree: 99.0 mol% or more), JM-33 (saponification degree: 93.5 to 95.5 mol%), JM-26 (saponification degree: 95.5 to 97.5 mol% (Saponification degree: 98.0 to 99.0 mol%) and JF-17 (saponification degree: 98.0 to 99.0 mol%), JF-17L (saponification degree: 98.0 to 99.0 mol% And can be suitably used in the present invention.

By forming such a polyvinyl alcohol-based resin, a polyvinyl alcohol-based resin layer is formed. The method of forming the polyvinyl alcohol-based resin is not particularly limited and a film can be formed by a known method. From the standpoint of easily obtaining a polarizer layer having a desired thickness, a solution of a polyvinyl alcohol- It is preferable to apply it to form a film.

Such a polyvinyl alcohol-based resin layer is stretched together with the base film and oriented, and a dichroic dye is adsorbed and oriented to form a polarizer layer. The draw ratio is preferably more than 5 times, more preferably more than 5 times, and also not more than 17 times.

The thickness of the polarizer layer (thickness of the polyvinyl alcohol-based resin layer after stretching) is preferably 10 占 퐉 or less, and more preferably 7 占 퐉 or less. By making the thickness of the polarizer layer 10 μm or less, a thin polarizer can be formed.

Examples of the dichroic dye used in the polarizer layer include iodine and organic dyes. Examples of the organic dyes include red BR, red LR, red R, pink LB, rubin BL, Borde GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, violet LB, violet B, , Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Kongorod, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky Blue, Direct First Orange S, and First Black. These dichroic substances may be used singly or in combination of two or more.

[Protection film]

The protective film may be a simple protective film having no optical function or a protective film having optical functions such as a retardation film and a brightness enhancement film.

Examples of the material of the protective film include, but are not limited to, a cyclic polyolefin resin film, a cellulose acetate resin film made of a resin such as triacetylcellulose and diacetylcellulose, a polyethylene terephthalate, a polyethylene naphthalate, a polybutylene terephthalate , A polycarbonate resin film, an acrylic resin film, a polypropylene resin film, and the like, which have been conventionally used in the field.

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., ZEONEX (manufactured by Nippon Zeon Co., Ltd.) and APEL (registered trademark) manufactured by Mitsui Kagaku Co., Ltd. can be suitably used. When a film of such a cyclic polyolefin-based resin is formed into a film, known methods such as a solvent casting method and a melt extrusion method are suitably used. In addition, pre-formed films such as Escherer (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.) and Zeonoa (registered trademark) film A commercial product of a film made of a cyclic polyolefin resin may be used.

The cyclic polyolefin-based resin film may be uniaxially or biaxially-stretched. By stretching, an arbitrary retardation value can be imparted to the cyclic polyolefin-based resin film. The stretching is usually performed continuously while unwinding the film roll, and is elongated 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 占 폚. 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, frame (flame) treatment and saponification treatment Do. Of these, plasma treatment and corona treatment that can be performed relatively easily are suitable.

Examples of the cellulose acetate based resin film include commercially available products such as Fujisak (registered trademark) TD80 (manufactured by Fuji Film Co., Ltd.), Fujisan (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.) ), KC4UY (manufactured by Konica Minolta Opt.), KC8UX2M (manufactured by Konica Minolta Opt.) And Fuji Tack (registered trademark) TD40UZ (manufactured by Fuji Film Co., Ltd.) Can be used to make.

A liquid crystal layer or the like may be formed on the surface of the cellulose acetate-based resin film in order to improve the viewing angle characteristics. Further, a cellulose acetate resin film may be stretched to give a retardation. In the cellulose acetate based resin film, in general, saponification treatment is carried out in order to improve the adhesion with the polarizing film. As the saponification treatment, a method of immersing in an aqueous alkaline solution such as sodium hydroxide or potassium hydroxide can be employed.

On the surface of the protective film as described above, an optical layer such as a hard coat layer, an antiglare layer, and an antireflection layer may be formed. Methods for forming these optical layers on the surface of the protective film are not particularly limited, and known methods can be used.

The thickness of the protective film is required to be as thin as possible from the requirement for thinning, preferably 90 m or less, and more preferably 50 m or less. If it is too thin, the strength is lowered and the workability is lowered, and therefore, it is preferably 5 m or more.

 ≪ Polarizing plate production method >

1 is a flowchart showing an outline of a method of manufacturing a polarizing plate using the present invention. The method for producing a double-sided polarizing laminated film of the present invention is characterized in that,

A resin layer forming step (S10) of forming a polyvinyl alcohol-based resin layer on both surfaces of the base film to obtain a double-side laminated film,

A stretching step (S20) of stretching the double-side laminated film,

(S30) of dyeing the polyvinyl alcohol-based resin layer on both sides of the stretched double-side laminated film with a dichroic dye and performing a crosslinking treatment to form a polarizer layer.

Further, in order to produce a polarizing plate or the like,

A cleaning drying step (S40) of washing and drying the double-side polarizing laminated film,

A protective film bonding step (S50) of bonding a protective film to both sides or one side of the double-side polarizing laminated film to obtain a double-side bonded film or a single-side bonded film,

A drying step (S60) of drying the double-side bonded film or the single-side bonded film,

A peeling step (S70) for peeling the polarizing plate, the polarizing plate with the base film attached thereto, or the one-side polarizing laminated film from the double-side bonded film or the single-side bonded film is carried out in this order.

The method for producing a double-sided polarizing laminated film of the present invention is characterized by forming a polyvinyl alcohol-based resin layer on both sides of a base film as well as on one side. With this manufacturing method, it is possible to suppress the curling of the film generated in the production process of the polarizing plate or the like, and to stably produce the film.

≪ Manufacturing process >

Hereinafter, the respective steps of S10 to S70 in Fig. 1 will be described in detail.

[Resin layer forming step (S10)]

Here, by forming a polyvinyl alcohol-based resin layer on both sides of the base film, a double-side laminated film composed of a base film and a polyvinyl alcohol-based resin layer can be obtained.

Materials suitable for the base film are as described in the description of the constitution of the above-mentioned polarizing laminated film. The base film is preferably one capable of being stretched in a temperature range suitable for stretching the polyvinyl alcohol-based resin.

The materials constituting the two polyvinyl alcohol-based resin layers formed on both surfaces of the base film are preferably the same material. In the case of different materials, the effect of curl suppression may be small.

If the difference in the thickness of the resin layer formed on both surfaces is remarkable, the effect of curl suppression becomes small. Therefore, it is preferable that the polyvinyl alcohol-based resin layer on both sides of the stretched double- It is preferable that the difference in thickness between both the resin layers is 3 占 퐉 or less. On the other hand, the specific thickness of the resin layer formed by the resin layer forming step (S10) is preferably from 3 탆 to 50 탆, more preferably from 5 탆 to 40 탆. If it is thinner than 3 占 퐉, the resulting film becomes thinner after stretching, resulting in deterioration of dyeability. On the other hand, if it exceeds 50 탆, the thickness of the finally obtained polarizer layer may exceed 10 탆.

The polyvinyl alcohol-based resin layer is preferably formed by coating a polyvinyl alcohol-based resin solution obtained by dissolving a polyvinyl alcohol-based resin powder in a good solvent on one surface of a substrate film, evaporating the solvent and drying the solution do. By forming the polyvinyl alcohol-based resin layer in this way, it becomes possible to thin the polyvinyl alcohol-based resin. Examples of the method for coating a polyvinyl alcohol resin solution on a base film include a roll coating method such as a wire-bar coating method, a reverse coating method and a gravure coating method, a die coating method, a comma coating method, a lip coating method, A screen coating method, a fountain coating method, a dipping method and a spraying method can be suitably selected and employed. The drying temperature is, for example, 50 占 폚 to 200 占 폚, preferably 60 占 폚 to 150 占 폚. The drying time is, for example, 2 to 20 minutes.

The application of the polyvinyl alcohol-based resin layer to both surfaces of the base film can be carried out one by one by one by one using the above-described method, or by using a dipping method, a spray coating method or other special apparatus, At the same time, the polyvinyl alcohol-based resin layer may be applied.

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 polyvinyl alcohol-based resin layer. The primer layer is preferably formed from a composition containing a polyvinyl alcohol-based resin and a cross-linking agent from the viewpoint of adhesion. Materials and the like suitable for the primer layer are as described in the description of the constitution of the above-mentioned polarizing plate.

In the case of forming the primer layer, the order of application to the base film is not particularly limited, and a polyvinyl alcohol-based resin layer may be further formed on both sides of the primer layer on both surfaces of the base film, A primer layer and a resin layer may be sequentially formed on the other surface of the base film after a primer layer and a polyvinyl alcohol resin layer are sequentially formed on one surface.

[Stretching step (S20)]

Here, the double-side laminated film obtained in the resin layer forming step (S10) is stretched. Preferably, the uniaxial stretching is performed so that the stretching magnification is more than 5 times and not more than 17 times. More preferably not less than 5 times and not more than 8 times. If the stretching magnification is 5 times or less, the polyvinyl alcohol-based resin layer is not sufficiently oriented, and as a result, the degree of polarization of the polarizer layer may not be sufficiently increased. On the other hand, when the draw ratio is more than 17 times, the laminated film tends to be broken at the time of stretching, and the thickness of the laminated film after stretching becomes thinner than necessary, which may lower the workability and handling property in a later process have. 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-stage stretching, the stretching process is performed so that the entire stages of the stretching process are combined so that the stretching ratio exceeds 5 times.

In the stretching step (S20) of the present embodiment, it is possible to perform a longitudinal stretching treatment for the longitudinal direction of the laminated film and a transverse stretching treatment for stretching the film in the width direction.

Examples of the longitudinal stretching method include a roll-to-roll stretching method and a compression stretching method, and the transverse stretching method includes a tenter method and the like.

The stretching treatment in the present invention is preferably carried out using a dry stretching method. The polyvinyl alcohol resin film (polarizer layer) thinner than conventional can be stretched at a high magnification without breakage by dry-stretching the polyvinyl alcohol resin layer before the dyeing process for each substrate film, and the resulting polarizer can be thinned Because.

[Dyeing process (S30)]

Here, the polyvinyl alcohol-based resin layer on both sides of the double-side laminated 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, Borde GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, violet LB, violet B, , Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Kongorod, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky Blue, Direct First Orange S, and First Black. 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 prepared 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 to 10 wt%, more preferably 0.02 to 7 wt%, and particularly preferably 0.025 to 5 wt%.

When iodine is used as the dichroic dye, it is preferable to further add iodide because 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 and titanium iodide. 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 immersing time of the stretched film in 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 step, the dyeing may be followed by a crosslinking treatment. The crosslinking treatment is carried out, for example, by immersing the laminated film in a solution (crosslinking solution) containing a crosslinking agent. As the crosslinking agent, conventionally known substances 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 which is compatible with water may be further 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 in the range of 6 to 15 wt%.

Iodide may be added to the crosslinking solution. By adding iodide, the polarization characteristics in the plane of the 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 0.05 to 15% by weight, more preferably 0.5 to 8% by weight.

The immersion 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 cross-linking solution is preferably in the range of 10 占 폚 to 80 占 폚.

 By the above dyeing step (S30), the polyvinyl alcohol-based resin layer has a function as a polarizer layer, and a double-sided polarizing laminated film can be obtained.

[Cleaning and drying step (S40)]

Next, a cleaning step for cleaning the double-side polarizing laminated film is not essential, but is preferably performed. In the cleaning step, a water washing treatment can be performed. The water washing treatment can usually be performed 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 from 2 to 300 seconds, preferably from 3 seconds to 240 seconds.

The cleaning step may be a combination of a cleaning treatment with a iodide solution and a water washing treatment, or a solution in which a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, or propanol is blended. After the cleaning step, a dewatering step using a nip roll, an air knife, or the like may be provided.

After the cleaning step, it is preferable to dry the double-side polarizing laminated film. In such drying, it is preferable to include a drying step at a temperature of 60 占 폚 or higher, and it is more preferable to include a drying step at a temperature of 70 占 폚 or higher. Of course, the drying step may include a multistage drying process at different temperatures. In this case, any drying step in the multistage drying step may be 60 DEG C or higher.

In addition to the temperature, it is also possible to optimize the circulation method of the hot air such as the air flow rate and the wind direction, or to add an IR heater for locally heating to strengthen the dry driving force. By these aids, the efficiency of drying is further improved and contributes to the improvement of productivity.

The upper limit of the drying temperature is preferably lower than the boiling point of water, and is preferably lower than 100 占 폚. Further, it is preferably 95 ° C or lower, and most preferably 90 ° C or lower.

[Protective film bonding step (S50)]

Here, a protective film is bonded to one side or both sides of the double-sided laminated film that has been subjected to the above-described processes. As a method of bonding the polarizer layer and the protective film, there is a method of bonding the polarizer layer and the protective film through a pressure-sensitive adhesive layer or an adhesive layer. Suitable materials for the protective film are as described in the description of the constitution of the above-mentioned polarizing plate.

(Pressure-sensitive adhesive layer)

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is usually composed of a composition obtained by using an acrylic resin, a styrene resin, a silicone resin or the like as a base polymer and adding thereto a crosslinking agent such as an isocyanate compound, an epoxy compound or an aziridine compound. Further, a pressure-sensitive adhesive layer showing light scattering property may be formed by blending fine particles into the pressure-sensitive adhesive.

The thickness of the pressure-sensitive adhesive layer is preferably from 1 탆 to 40 탆, but it is preferably thinly coated, more preferably from 3 탆 to 25 탆, within a range not deteriorating the workability and durability. When the thickness is from 3 m to 25 m, it has good processability and is also suitable for suppressing the dimensional change of the polarizing film. If the pressure-sensitive adhesive layer is thinner than 1 占 퐉, the pressure-sensitive adhesive property is deteriorated. If it exceeds 40 占 퐉, the pressure-sensitive adhesive is likely to be pushed out.

The method of forming the pressure-sensitive adhesive layer on the protective film or the polarizer is not particularly limited, and a solution containing each component including the above-mentioned base polymer is applied to the surface of the protective film or the polarizer layer and dried to form a pressure- After that, a pressure-sensitive adhesive layer may be formed on the separator and then laminated on the protective film surface or the polarizer layer surface. When the pressure-sensitive adhesive layer is formed on the protective film or polarizer layer surface, adhesion treatment, for example, corona treatment, or the like may be performed on one side or both sides of the protective film or the polarizer layer side or the pressure-

(Adhesive layer)

As the adhesive constituting the adhesive layer, there can be enumerated, for example, an aqueous adhesive using a polyvinyl alcohol resin aqueous solution, an aqueous two-component emulsion type emulsion adhesive, and the like. Among them, a polyvinyl alcohol-based resin aqueous solution is suitably used. The polyvinyl alcohol-based resin used as the adhesive includes a vinyl alcohol homopolymer obtained by saponifying a polyvinyl acetate which is a homopolymer of vinyl acetate, a vinyl alcohol 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 of these polymers. As the water-based adhesive, polyvalent aldehyde, water-soluble epoxy compound, melamine compound, zirconia compound, zinc compound or the like may be added as an additive. When such a water-based adhesive is used, the thickness of the adhesive layer obtained next is usually much thinner than 1 占 퐉, 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 film using the water-based adhesive is not particularly limited, and a method in which an adhesive is uniformly applied or introduced onto the surface of the film, and the other film is scratched on the coated surface with a roll or the like and dried . Usually, the adhesive is applied at a temperature of 15 ° C to 40 ° C after its preparation, and the bonding temperature is usually in the range of 15 ° C to 30 ° C.

When an aqueous adhesive is used, the film is bonded and then dried to remove water contained in the aqueous adhesive. The temperature of the drying furnace is preferably 30 占 폚 to 90 占 폚. The bonding surface tends to be easily peeled off at a temperature lower than 30 ° C. There is a possibility that the optical performance of a polarizer or the like is deteriorated by heat at a temperature higher than 90 ° C. The drying time may be generally from 10 to 1000 seconds.

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

As the non-aqueous adhesive, a photo-curable adhesive may be used. Examples of the photo-curable adhesive include a mixture of a photo-curable epoxy resin and a photo cationic polymerization initiator.

As a method of bonding the film with the photo-curable adhesive, conventionally known methods can be used. Examples of the method include a flexible method, a Meyer-bar coat method, a gravure coat method, a comma coater method, a doctor blade method, a die coat method, A method in which an adhesive is applied to the adhesive surface of the film by a method, a spraying method or the like, and two films are overlapped with each other. The flexible method is a method in which an adhesive is applied to a surface of a film to be coated while moving two films in a substantially vertical direction, a substantially horizontal direction, or an inclined direction therebetween.

After the adhesive is applied to the surface of the film, the film is sandwiched between the nip rolls and the like to be bonded. It is also possible to suitably use a method of pressing the laminate with a roll or the like and spreading it evenly. In this case, metal, rubber, or the like can be used as the material of the roll. It is also preferable to adopt a method in which the laminate is passed between a roll and a roll, followed by pressing and spreading. 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 5 占 퐉 or less and 0.01 占 퐉 or more.

The adhesive surface of the film may be appropriately subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, frame (flame) treatment, saponification treatment, etc., in order to improve adhesion.

As the saponification treatment, there may be mentioned a method of immersing in an aqueous alkaline solution such as sodium hydroxide or potassium hydroxide.

When a photo-curable resin is used as the adhesive, the photo-curable adhesive is cured by laminating the film and then irradiating an active energy ray. The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution with 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 to the photo-curable 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 activation of the polymerization initiator is 0.1 to 6000 mW / cm 2. When the irradiation intensity is not less than 0.1 mW / cm 2, the reaction time is not excessively long. When the irradiation intensity is not more than 6000 mW / cm 2, the heat radiated from the light source and the heat generated during curing of the photo-curing adhesive deteriorate the yellowing of the epoxy resin, . The light irradiation time to the photo-curable adhesive is not particularly limited as long as it is applied in accordance with the photo-curable adhesive to be cured, but may be set so that the integrated light quantity indicated as the product of the irradiation intensity and the irradiation time is 10 to 10000 mJ / . When the accumulated light quantity for the photo-curing adhesive is 10 mJ / cm 2 or more, a sufficient amount of active species originating from the polymerization initiator is generated sufficiently to allow the curing reaction to proceed more surely. When the amount is 10,000 mJ / cm 2 or less, , And good productivity can be maintained. The thickness of the adhesive layer after irradiation with active energy rays is usually about 0.001 to 5 占 퐉, preferably 0.01 占 퐉 to 2 占 퐉, more preferably 0.01 占 퐉 to 1 占 퐉.

In the case of curing the photo-curing adhesive of a film containing a polarizer layer or a protective film by irradiation of an active energy ray, the conditions such as the polarization degree of the polarizer layer, the transmittance and the hue, and the transparency of the protective film, It is preferable to carry out curing.

[Drying process (S60)]

When a solution containing a solvent is used to form the adhesive layer or the pressure-sensitive adhesive layer in the protective film bonding step (S50), the double-side bonded film or the single-side bonded film is dried. In this drying step, it is mainly intended to dry the adhesive layer or the pressure-sensitive adhesive layer, and the drying conditions and the like are the same as those in the cleaning and drying step (S40). Particularly, in the case of using a polyvinyl alcohol-based resin aqueous solution or the like in order to form an adhesive layer, it is preferable to carry out drying at a temperature of 60 占 폚 or more.

[Peeling step (S70)]

After the drying step (S60), a peeling step (S70) for peeling the polarizing plate, the polarizing plate with the base film attached thereto, or the one-side polarizing laminated film is carried out from the double-side bonded film or one-side bonded film. The method of peeling the polarizing plate, the polarizing plate with the base film, or the one-side polarizing laminated film is not particularly limited, and the same method as that of the peeling film peeling process performed by a polarizing plate with a usual adhesive can be adopted. After the drying step (S60), it may be peeled off immediately in this state, or it may be peeled off by separately taking up a peeling step after winding in roll form.

[Other optical layers]

The polarizing plate obtained in the present invention can be used as a polarizing plate in which other optical layers are laminated in practice. Further, the protective film 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 a property opposite to that of the polarized light, 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.

Commercially available products corresponding to a reflection type polarizing film that transmits polarized light of a certain kind and reflects polarized light exhibiting a property opposite to the polarized light are DBEF (available from 3M Company, available from Sumitomo 3M Ltd.), APF [ 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 substrate surface 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 to which the liquid crystal compound is applied on the surface of the base material, there are WV film (manufactured by Fuji Film), NH film (manufactured by Shin-Nippon Sekiyu Co., Ltd.) (Manufactured by Nippon Sekiyu Co., Ltd.). As a commercially available product corresponding to a retardation film made of a cyclic polyolefin resin, commercially available products such as ATON (registered trademark) film (manufactured by JSR Corporation), Escherer (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.) (Registered trademark) film (manufactured by OPTIS Co., Ltd.).

Example

Example 1

The production up to the double-sided polarizing laminated film 302 was carried out as shown in the flow chart shown in Fig.

(Substrate film)

(Homopolymer of propylene) homopolymer of propylene at both sides of a resin layer composed of a random copolymer of propylene / ethylene containing about 5% by weight of an ethylene unit ("Sumitomonobrene W151" manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = Layer structure in which a resin layer composed of polypropylene (Sumitomono Blend 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 Respectively. The total thickness of the obtained base film (1) was 90 占 퐉, and the ratio of the thickness of each layer (FLX80E4 / W151 / FLX80E4) was 3/4/3.

(Primer layer forming step)

An aqueous solution having a concentration of 3% by weight was prepared by dissolving polyvinyl alcohol powder (trade name: Z-200, manufactured by Nihon Seika Kagaku Kogyo Co., Ltd., average polymerization degree: 1100, average saponification degree: 99.5 mol%) in hot water at 95 캜. 5 parts by weight of a crosslinking agent (trade name: Sumirez (registered trademark) Resin 650, manufactured by Sumitomo Chemical Co., Ltd.) was mixed with 6 parts by weight of polyvinyl alcohol powder to obtain a primer solution. One surface of the base film 1 was subjected to corona treatment, and the primer solution was applied using a micro gravure coater and dried at 80 DEG C for 10 minutes to form a primer layer having a thickness of 0.2 mu m.

A corona treatment was also applied to the other side of the base film and a coating of the same primer solution was carried out to prepare a film having a primer layer formed on both sides of the base film 1.

(Resin layer forming step)

A polyvinyl alcohol aqueous solution having a concentration of 8% by weight was prepared by dissolving a polyvinyl alcohol powder (trade name: PVA124, Kuraray Co., Ltd., average degree of polymerization: 2400, average saponification degree: 98.0 to 99.0 mol%) in hot water at 95 캜. The obtained aqueous solution was coated on the surface of the primer layer formed on one surface of the substrate film 1 by using a lip coater and successively dried at 80 캜 for 2 minutes, at 70 캜 for 2 minutes and at 60 캜 for 4 minutes, A two-layered laminated film 201 consisting of a film 1 and a polyvinyl alcohol-based resin layer 21 was produced.

The same coating treatment was applied to the surface of the primer layer formed on the other side of the base film 1 to form the polyvinyl alcohol resin layer 21, the base film 1 and the polyvinyl alcohol resin layer 22 ) Was formed on the both side laminated film 202. The thicknesses of the polyvinyl alcohol resin layers 21 and 22 (before stretching) at this time were 10.5 占 퐉 and 10.2 占 퐉, respectively.

(Drawing step)

The double-side laminated film 202 was subjected to free-end uniaxial stretching at 160 占 폚 at 5.8 times using an inter-roll longitudinal stretching machine. The thicknesses of the two polyvinyl alcohol-based resin layers of the double-side laminated film after stretching were 5.1 占 퐉 and 4.9 占 퐉, respectively. The double-side laminated film 202 after stretching has almost no curl and is flat and has excellent handling properties in the stretching process.

Further, the pieces cut out from the stretched double-side laminated film were allowed to stand for 5 days under an environment of 23 ° C and 50% RH, but no curling occurred and a good shape was maintained.

(Dyeing process)

The stretched double-side laminated film was immersed in a warm bath at 60 DEG C for 60 seconds and then dipped in a dyeing solution which is a mixed aqueous solution of iodine and potassium iodide at 30 DEG C for about 150 seconds to be dyed. The liquid was washed away. Subsequently, the substrate was immersed in a crosslinking solution of a mixed aqueous solution of boric acid and potassium iodide at 76 DEG C for 600 seconds.

(Washing and drying process)

Thereafter, the double-side laminated film was washed with pure water at 10 캜 for 4 seconds, and finally dried at 80 캜 for 300 seconds. The double-side polarizing laminated film 302 was obtained by using the polyvinyl alcohol resin layers 21 and 22 formed on both surfaces of the base film 1 as the polarizer layers 31 and 32 by the above process. At the time of drying, curling was scarcely generated, and a double-side polarizing laminated film could be continuously produced in a good state.

The mixing ratio of the dye solution and the crosslinking solution was as follows.

<Dyeing solution>

Water: 100 parts by weight

Iodine: 0.6 parts by weight

Potassium iodide: 10 parts by weight

&Lt; Crosslinking solution &

Water: 100 parts by weight

Boric acid: 9.5 parts by weight

Potassium iodide: 5 parts by weight

Example 2

The polarizing plates 501a and 501b were manufactured from the double-side polarizing laminated film 302 to the polarizing plates 501a and 501b as shown in the flow chart shown in FIG.

(Protective film bonding step)

An aqueous solution having a concentration of 3% by weight was prepared by dissolving a polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree: 1800, trade name: KL-318) in hot water at 95 캜. 1 part by weight of a crosslinking agent (trade name: Sumirez (registered trademark) Resin 650, manufactured by Sumitomo Chemical Co., Ltd.) was added to the obtained aqueous solution to 2 parts by weight of polyvinyl alcohol powder to prepare an adhesive solution. The above-described polyvinyl alcohol adhesive was applied to both surfaces of the double-sided polarizing laminated film 302 obtained in Example 1, and then the protective films 41 and 42 (TAC: KC4UY manufactured by Konica Minolta Opt.) Were bonded , And dried at 80 DEG C for 5 minutes to form a double-side bonded film 402 consisting of five layers of the protective film 41, the polarizer layer 31, the base film 1, the polarizer layer 42 and the protective film 42 .

(Drying step and peeling step)

The polarizing plate 501a made of the polarizer 31 and the protective film 41 was peeled from the double-sided adhesive film 402. The base film is peeled off from the remaining film (film comprising the base film 1, the polarizer layer 32 and the protective film 42) to form a polarizing plate 501b composed of the polarizing layer 32 and the protective film 42 .

The base film 1 was easily peeled off from the polarizing plates 501a and 501b formed on both sides thereof. The thicknesses of the polarizer layers 31 and 32 of the obtained two polarizers 501a and 501b were all 5.0 μm.

Example 3

In the same manner as in Example 1, a double-side laminated film was obtained. The thicknesses of the polyvinyl alcohol resin layers 21 and 22 (before stretching) at this time were 25.2 탆 and 28.7 탆, respectively. This double-side laminated film was fixed at a constant titer of 5.8 times at 160 캜 using a tenter stretching apparatus, and then uniaxially stretched to obtain a stretched film. The thickness of the polyvinyl alcohol resin layer after stretching was 4.6 탆 and 4.9 탆, respectively. The double-side laminated film 202 after stretching was flat with almost no curl, and the handling property in the stretching process was also excellent.

Further, the pieces cut out from the stretched double-side laminated film were allowed to stand for 5 days under an environment of 23 ° C and 50% RH, but no curling occurred and a good shape was maintained.

Thereafter, in the same manner as in Example 1, the stretched double-side laminated film was dyed. However, even when dried after dyeing, almost no curl occurred, and the double-sided polarizing laminated film could be continuously produced in a good shape.

Example 4

As shown in the flow chart of Fig. 3, a double-side polarizing laminated film was obtained in the same manner as in Example 1. Fig. Thereafter, the protective film 41 was bonded to only one side of the double-side polarizing laminated film 302 in the same manner as in Example 2, and the protective film 41, the polarizer layer 31, and the base film 1 / polarizer layer 32. The single-sided bonding film 401 of the four-layer structure shown in Fig.

From this film, the polarizing plate 501 (the polarizing layer 31 and the protective film 41) was peeled off. The remaining base film (1) and polarizer layer (32) become a polarizing laminated film (601). According to this manufacturing method, the polarizing plate 501 and the single-sided polarizing laminated film 601 can be obtained at the same time.

Comparative Example 1

A stretched film was produced in the same manner as in Example 1 except that the primer layer and the resin layer were formed on only one side of the base film. Since the resin layer was formed only on one side, the obtained film was in a state in which curling easily occurred, and the handling property was insufficient. Further, when the obtained film was allowed to stand under an environment of 23 占 폚 and 50% RH, the curl became even larger. In addition, the film produced by such a conventional method can be used without any problem if tension is applied on a production line. However, since the handling becomes difficult due to poor handling property once the film is wound, For reasons of convenience, it was unsuitable for a case where a winding process was desired.

Subsequently, this stretched film was stained by the same dyeing step as in Example 1 to obtain a polarizing laminated film. However, during drying, significant curling to such an extent that the film could not be transported was generated, Causing folding problems. As a result, a polarizing laminated film could not be obtained continuously and stably.

1: substrate film
21, 22: polyvinyl alcohol-based resin layer
201: single side laminated film
202: double-side laminated film
31, 32: Polarizer layer
302: Double-sided polarizing laminated film
41, 42: protective film
401: single-side bonded film
402: double-sided bonded film
501, 501a and 501b:
601: Single-side polarizing laminated film

Claims (16)

A method for producing a double-side polarizing laminated film comprising a base film and a polarizer layer formed on both sides of the base film,
A resin layer forming step of forming a polyvinyl alcohol resin layer on both surfaces of the base film to obtain a double-side laminated film,
A stretching step of stretching the double-side laminated film,
Wherein the polyvinyl alcohol resin layer on both sides of the stretched double-side laminated film is dyed with a dichroic dye, and a cross-linking treatment is performed to form a polarizer layer by a double-side polarizing laminated film &Lt; / RTI &gt; The method for producing a double-side polarizing laminated film according to claim 1, wherein the material constituting the polyvinyl alcohol-based resin layer on both sides of the double-side laminated film is the same material. The method for producing a double-side polarizing laminated film according to claim 1 or 2, wherein a difference in thickness of the polyvinyl alcohol-based resin layer on both sides of the stretched double-side laminated film is 3 m or less. The method for producing a double-side polarizing laminated film according to claim 3, wherein the stretching step is conducted at a draw ratio of more than 5 times. The method for producing a double-side polarizing laminated film according to claim 3, wherein the thickness of each of the polarizer layers on both sides of the double-sided polarizing laminated film is 10 mu m or less. A polarizing plate comprising a polarizer layer and a protective film formed on one side of the polarizer layer,
A protective film joining step of joining a protective film to both surfaces of a double-sided polarizing laminated film obtained by the production method according to claim 1 to obtain a double-sided bonded film,
And a peeling step of peeling off at least one polarizing plate from the double-side bonded film in this order. 7. The polarizing plate manufacturing method according to claim 6, wherein in the peeling step, the two polarizing plates on both sides of the double-side bonded film are simultaneously peeled off. 7. The polarizing plate manufacturing method according to claim 6, wherein in the peeling step, the polarizing plate on one side of the double-side bonded film is peeled off, and subsequently the polarizing plate on the other side is peeled off. A polarizing plate comprising a polarizer layer, a protective film formed on one surface of the polarizer layer, and a base film bonded to one surface of the polarizer layer,
A protective film joining step of joining a protective film to both surfaces of a double-sided polarizing laminated film obtained by the production method according to claim 1 to obtain a double-sided bonded film,
And a peeling step of peeling the polarizing plate having the base film attached thereon from the double-side bonded film in this order. A polarizing plate comprising a polarizer layer and a protective film formed on one side of the polarizer layer,
A protective film joining step of joining a protective film to one surface of a double-sided polarizing laminated film obtained by the manufacturing method according to claim 1 to obtain a single-
And a peeling step of peeling the polarizing plate from the one-side bonded film in this order. A method for producing a single-sided polarizing laminated film comprising a base film and a polarizer layer formed on one side of the base film,
A protective film joining step of joining a protective film to one surface of a double-sided polarizing laminated film obtained by the manufacturing method according to claim 1 to obtain a single-
And a peeling step of peeling the single-sided polarizing laminated film from the single-sided laminated film in this order. delete delete delete delete delete

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