JP5143918B2 - Manufacturing method of polarizing laminated film, polarizing plate or polarizing plate with substrate film - Google Patents

Description

  The present invention relates to a polarizing laminate film, a method for producing a polarizing plate or a polarizing plate with a substrate film, and a double-sided laminated film, a double-sided polarizing laminated film, a double-sided laminated film, and a single-sided laminated film.

  A polarizing plate is widely used as a polarization supplying element 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 resin and a protective film made of triacetyl cellulose are conventionally used. However, in recent years, notebook personal computers for liquid crystal display devices have been used. With the development of mobile devices such as mobile phones and mobile phones, there is a need to reduce the thickness and weight.

  Conventionally, after a film made of a polyvinyl alcohol resin is stretched alone or while being stretched, a polarizing film is produced by performing a dyeing treatment or a crosslinking treatment, and laminating this on a protective film or the like to form a polarizing plate. Although it was manufactured, it was possible to reduce the thickness only to the limit thickness of the polarizing film alone. For this reason, after providing the polyvinyl alcohol-type resin layer of a polarizer layer on the surface of a base film, the polyvinyl alcohol-type resin layer is extended | stretched with the base film, and after passing through a dyeing | staining and bridge | crosslinking process and a subsequent drying process, a polyvinyl alcohol type By making the resin layer a polarizer layer, the total thickness of the base film and the polarizer layer can be reduced to the limit, and the thickness as the polarizer layer (polarizing film) can be made thinner than before. A method is known (see, for example, Patent Document 1).

  However, in the method described in Patent Document 1, in the drying step immediately after the cross-linking step, there is a problem that the cross-linking reaction proceeds remarkably and the polyvinyl alcohol resin layer shrinks in the width direction of the film. In this case, when the film is to be produced continuously, only the polyvinyl alcohol-based resin layer of the laminated film composed of the base film and the polyvinyl alcohol-based resin layer contracts in the width direction, so that the polyvinyl alcohol-based resin layer together with the base film There was a problem that the end of the fold would be folded. Further, when the laminated film after stretching is left as it is, there has been a problem that the curl of the film is generated due to water absorption and stretching of the polyvinyl alcohol resin layer on one side.

JP 2000-338329 A

  In view of the above-mentioned problems, the present invention is a thin film and a polarizing film having a high polarizing performance. In the production process of the polarizing film, the stretching process, the drying process after dyeing, or the storage of the stretched film is generated. The purpose is to suppress curling.

The present invention is a method for producing a double-sided polarizing laminate film comprising a base film and a polarizer layer formed on both sides of the base film,
A resin layer forming step of obtaining a double-sided laminated film by forming a polyvinyl alcohol-based resin layer on both sides of the base film;
A stretching step of stretching the double-sided laminated film;
A double-sided polarizability comprising, in this order, a dyeing step of forming a polarizer layer by dyeing the polyvinyl alcohol-based resin layer on both sides of the double-sided laminated film after stretching with a dichroic dye and performing a crosslinking treatment It is a manufacturing method of a laminated film.

  It is preferable that the material which comprises the polyvinyl alcohol-type resin layer of both surfaces of the said double-sided laminated film is the same material.

  The difference in the thickness of the polyvinyl alcohol-based resin layer on both sides of the double-sided laminated film after stretching is preferably 3 μm or less.

In the stretching step, stretching is preferably performed at a stretching ratio of more than 5 times.
The thickness of each of the polarizer layers on both sides of the double-sided polarizing laminate film is preferably 10 μm or less.

Further, the present invention is a method for producing a polarizing plate comprising a polarizer layer and a protective film formed on one surface of the polarizer layer,
A protective film laminating step for obtaining a double-sided laminated film by laminating a protective film on both sides of the double-sided polarizing laminate film obtained by the above production method;
It is related also with the manufacturing method of a polarizing plate including the peeling process which peels at least 1 said polarizing plate from the said double-sided bonding film in this order.

  In the said peeling process, it is preferable to peel simultaneously the two polarizing plates of both surfaces of the said double-sided bonding film.

  In the peeling step, it is preferable to peel the polarizing plate on one side of the double-sided laminated film and then peel the polarizing plate on the other side.

In addition, the present invention includes a polarizer layer, a protective film formed on one surface of the polarizer layer, and a substrate film bonded to one surface of the polarizer layer. A method of manufacturing a polarizing plate,
A protective film laminating step for obtaining a double-sided laminated film by laminating a protective film on both sides of the double-sided polarizing laminate film obtained by the above production method;
It is related also with the manufacturing method of the polarizing plate with a base film which includes the peeling process which peels the said polarizing plate with a base film from the said double-sided bonding film in this order.

Further, the present invention is a method for producing a polarizing plate comprising a polarizer layer and a protective film formed on one surface of the polarizer layer,
A protective film laminating step for obtaining a single-sided laminated film by laminating a protective film on one surface of the double-sided polarizing laminate film obtained by the above production method;
It is related also with the manufacturing method of a polarizing plate including the peeling process which peels the said polarizing plate from the said single-sided bonding film in this order.

Further, the present invention is a method for producing a single-sided polarizing laminated film comprising a base film and a polarizer layer formed on one surface of the base film,
A protective film laminating step for obtaining a single-sided laminated film by laminating a protective film on one surface of the double-sided polarizing laminate film obtained by the above production method;
It is related also with the manufacturing method of the single-sided polarizing laminated film which includes the peeling process which peels off the said single-sided polarizing laminated film from the said single-sided bonding film in this order.

  Furthermore, this invention relates also to the double-sided laminated film provided with the base film and the polyvinyl alcohol-type resin layer formed in both surfaces of this base film.

  Moreover, this invention relates also to the double-sided laminated film provided with the base-material film and the polyvinyl alcohol-type resin layer formed in the both surfaces of this base-film, and orientated.

  The present invention also relates to a base film and a double-sided polarizing laminate film comprising a polyvinyl alcohol resin layer formed on both sides of the base film, oriented, and adsorbed with a dichroic dye.

  The present invention also includes a base film, a double-sided polarizing laminate film comprising a polarizer layer formed on both sides of the base film, and a protective film bonded to both sides of the double-sided polarizing laminate film, It also relates to a double-sided laminated film.

  In addition, the present invention provides a base film, a double-sided polarizing laminate film comprising a polarizer layer formed on both sides of the base film, and a protection bonded to one side of the double-sided polarizing laminate film The present invention also relates to a single-sided laminated film consisting of a film.

  In the present invention, since a treatment such as stretching, dyeing and drying is performed with the polyvinyl alcohol resin layer formed on both surfaces of the base film, curling of the film generated in the manufacturing process of the polarizing plate or the like is suppressed. And stable production becomes possible.

  Further, in the stretching process, the dyeing process, and the bonding process, a polyvinyl alcohol resin layer having a double area (both sides) can be treated at one time, and the production efficiency of the polarizing plate is improved. Furthermore, it is not necessary to use a special drying furnace at the time of drying in each manufacturing process, and the cost in terms of equipment can be reduced.

It is a flowchart which shows the outline | summary of the manufacturing method of the polarizing plate of this invention. It is a flowchart for demonstrating the manufacturing method of the double-sided polarizing laminated film of Example 1, and the manufacturing method of the polarizing plate of Example 2. FIG. 10 is a flowchart for explaining a manufacturing method of the polarizing plate of Example 3.

  In this specification, the laminated body provided with the polyvinyl alcohol-type resin layer (layer which consists of polyvinyl alcohol-type resin) on one side of a base film is called a "single area layer film", and it is on both sides of a base film. The laminated body provided with the polyvinyl alcohol-based resin layer is referred to as “double-sided laminated film”.

  Moreover, a polyvinyl alcohol-based resin layer having a function as a polarizer is referred to as a “polarizer layer”, and a laminate including a polarizer layer on one surface of a base film is referred to as a “single-sided polarizing laminate film”. A laminate having a polarizer layer on both sides of the base film is referred to as a “double-sided polarizing laminate film”. Moreover, the laminated body provided with the protective film on one surface of the polarizer layer is referred to as “polarizing plate”. Hereinafter, each component will be described in detail.

[Base film]
As the resin used for the base film, for example, thermoplastic resins excellent in transparency, mechanical strength, thermal stability, stretchability, etc. are used, and an appropriate resin can be selected according to their Tg or Tm. Specific examples of thermoplastic resins include polyolefin resins, polyester resins, cyclic polyolefin resins (norbornene resins), (meth) acrylic resins, cellulose ester resins, polycarbonate resins, polyvinyl alcohol resins, vinyl acetate. Resin, polyarylate resin, polystyrene resin, polyethersulfone resin, polysulfone resin, polyamide resin, polyimide resin, and mixtures and copolymers thereof.

  The base film may be a film made of only one kind of the above-mentioned resin, or may be a film made 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 resin include polyethylene and polypropylene, which are preferable because they can be stably stretched at a high magnification. Further, an ethylene-polypropylene copolymer obtained by copolymerizing propylene with ethylene can also be used. Copolymerization can be performed with other types of monomers, and examples of other types of monomers copolymerizable with propylene include ethylene and α-olefins. As the α-olefin, an α-olefin having 4 or more carbon atoms is preferably used, and more preferably an α-olefin having 4 to 10 carbon atoms. Specific examples of the α-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, 4-methyl-1-pentene; vinylcyclohexane and the like. The copolymer of propylene and other monomers copolymerizable therewith may be a random copolymer or a block copolymer. The content of the structural unit derived from the other monomer in the copolymer is determined by infrared (IR) spectrum according to the method described on page 616 of “Polymer Analysis Handbook” (1995, published by Kinokuniya). It can be obtained by measuring.

  Among the above, propylene-based resins constituting the propylene-based resin film include propylene homopolymer, propylene-ethylene random copolymer, propylene-1-butene random copolymer, and propylene-ethylene-1-butene. Random copolymers are preferably used.

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

  The polyester resin is a polymer having an ester bond and is mainly a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the polyvalent carboxylic acid used, divalent dicarboxylic acid is mainly used, and examples thereof include isophthalic acid, terephthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. In addition, divalent diol is mainly used as the polyhydric alcohol used, and examples thereof include propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Specific examples of the resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate, and the like. . These blend resins and copolymers can also be suitably used.

  As the cyclic polyolefin resin, a norbornene resin is preferably used. Cyclic polyolefin resin is a general term for resins that are polymerized using cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as cyclic polyolefin resins. As specific examples, Topas (registered trademark) (manufactured by Ticona), Arton (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (manufactured by Nippon Zeon Corporation), ZEONEX (ZEONEX) (Registered trademark) (manufactured by ZEON CORPORATION) and Apel (registered trademark) (manufactured by Mitsui Chemicals, Inc.).

  Any appropriate (meth) acrylic resin can be adopted as the (meth) acrylic resin. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester -(Meth) acrylic acid copolymer, (meth) acrylic acid methyl-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer) And methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, C1-6 alkyl poly (meth) acrylates, such as poly (meth) acrylate methyl, are mentioned. More preferably, as the (meth) acrylic resin, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

  The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, these copolymers and those obtained by modifying a part of the hydroxyl group with other types of substituents are also included. Among these, cellulose triacetate is particularly preferable. Many products of cellulose triacetate are commercially available, which 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 Co., Ltd.), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UZ (Fuji Film ( Co., Ltd.), Fujitac (registered trademark) TD40UZ (Fuji Film Co., Ltd.), KC8UX2M (Konica Minolta Opto Co., Ltd.), KC4UY (Konica Minolta Opto Co., Ltd.), and the like.

  The polycarbonate resin is an engineering plastic made of a polymer in which monomer units are bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, and flame retardancy. Moreover, since it has high transparency, it is suitably used in optical applications. In optical applications, resins called modified polycarbonates in which the polymer skeleton is modified in order to lower the photoelastic coefficient, copolymerized polycarbonates with improved wavelength dependency, and the like are commercially available and can be suitably used. Such polycarbonate resins are widely commercially available. For example, Panlite (registered trademark) (Teijin Chemicals Ltd.), Iupilon (registered trademark) (Mitsubishi Engineering Plastics), SD Polyca (registered trademark) (Sumitomo) Dow Co., Ltd.), Caliber (registered trademark) (Dow Chemical Co., Ltd.) and the like.

  Arbitrary appropriate additives other than said thermoplastic resin may be added to the base film. Examples of such additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and coloring agents. . 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, and particularly preferably 70 to 97%. % By weight. This is because, if the content of the thermoplastic resin in the base film is less than 50% by weight, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited.

  Although the thickness of the base film before stretching can be determined as appropriate, in general, from the viewpoint of workability such as strength and handleability, it is preferably 1 to 500 μm, more preferably 1 to 300 μm, and still more preferably 5 to 5 μm. 200 μm, most preferably 5 to 150 μm.

  The base film may be subjected to corona treatment, plasma treatment, flame treatment or the like on at least the surface on which the polyvinyl alcohol resin layer is formed in order to improve the adhesion with the polyvinyl alcohol resin layer. Moreover, in order to improve adhesiveness, you may form thin layers, such as a primer layer and an adhesive bond layer, in the surface of the side by which the polyvinyl alcohol-type resin layer of a base film is formed.

(Primer layer)
When the primer layer is formed on the surface of the base film on which the polarizer layer is formed, the primer layer is a material that exhibits a certain degree of strong adhesion to both the base film and the polyvinyl alcohol resin layer. If there is no particular limitation. For example, a thermoplastic resin excellent in transparency, thermal stability, stretchability, etc. is used. Specific examples include acrylic resins and polyvinyl alcohol resins, but are not limited thereto. Among these, a polyvinyl alcohol resin having good adhesion is preferably used.

  As a polyvinyl alcohol-type resin used as a primer layer, polyvinyl alcohol resin and its derivative (s) are mentioned, for example. Derivatives of polyvinyl alcohol resin include polyvinyl formal, polyvinyl acetal, etc., olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, and alkyl esters of unsaturated carboxylic acids. And those modified with acrylamide or the like. Among the above-mentioned polyvinyl alcohol-based resin materials, it is preferable to use a polyvinyl alcohol resin.

  In order to increase the strength of the primer layer, a crosslinking agent may be added to the thermoplastic resin. As the cross-linking agent to be added to the thermoplastic resin, known ones such as organic and inorganic can be used. What is necessary is just to select a more suitable thing suitably with respect to the thermoplastic resin to be used. For example, in addition to low molecular crosslinkers such as epoxy crosslinkers, isocyanate crosslinkers, dialdehyde crosslinkers, metal chelate crosslinkers, high molecular weight polymers such as methylolated melamine resins and polyamide epoxy resins. A crosslinking agent or the like can also be used. When a polyvinyl alcohol resin is used as the thermoplastic resin, it is particularly preferable to use a polyamide epoxy resin, a methylolated melamine, a dialdehyde, a metal chelate crosslinking agent, or the like as the crosslinking agent.

  The thickness of a primer layer becomes like this. Preferably it is 0.05-1 micrometer, More preferably, it is 0.1-0.4 micrometer. If the thickness is less than 0.05 μm, the adhesion between the base film and the polyvinyl alcohol layer is reduced, and if it is greater than 1 μm, the polarizing plate becomes thick.

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

  As the polyvinyl alcohol resin constituting the polyvinyl alcohol resin layer, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with 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 resin constituting the polarizer layer (polyvinyl alcohol resin layer) is preferably a completely saponified product. The range of the saponification degree is preferably 80.0 mol% to 100.0 mol%, more preferably 90.0 mol% to 99.5 mol%, and further 94.0 mol%. Most preferred is a range of ˜99.0 mol%. When the degree of saponification is less than 80.0 mol%, there is a problem that the water resistance and heat-and-moisture resistance after the polarizing plate are remarkably inferior. In addition, when a polyvinyl alcohol-based resin having a saponification degree exceeding 99.5 mol% is used, the dyeing speed is remarkably slow, and a polarizing laminated film having sufficient polarization performance may not be obtained. In some cases, the production takes several times longer than usual.

The saponification degree as used herein is a unit ratio (mol%) representing the ratio of the acetate group contained in the polyvinyl acetate resin, which is a raw material for the polyvinyl alcohol resin, to a hydroxyl group by the saponification step. Is a numerical value defined by the following formula. It can be determined by the method defined in JIS K 6726 (1994).

Saponification degree (mol%) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100

The higher the degree of saponification, the higher the proportion of hydroxyl groups, that is, the lower the proportion of acetate groups that inhibit crystallization.

  Further, the polyvinyl alcohol resin used in the present invention may be a modified polyvinyl alcohol partially modified. For example, polyvinyl alcohol resins modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, alkyl esters of unsaturated carboxylic acids, acrylamide, and the like can be used. The proportion of modification is preferably less than 30 mol%, and more preferably less than 10%. When modification exceeding 30 mol% is performed, it becomes difficult to adsorb the dichroic dye, resulting in a problem that the polarization performance is 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 1500 to 8000, and most preferably 2000 to 5000. The average degree of polymerization here is also a numerical value determined by a method defined by JIS K 6726 (1994).

  Examples of the polyvinyl alcohol resin having such characteristics include PVA124 (degree of saponification: 98.0 to 99.0 mol%) and PVA117 (degree of saponification: 98.0 to 99.0) manufactured by Kuraray Co., Ltd. Mol%), PVA624 (degree of saponification: 95.0-96.0 mol%) and PVA617 (degree of saponification: 94.5-95.5 mol%); for example, AH- manufactured by Nippon Synthetic Chemical Industry Co., Ltd. 26 (degree of saponification: 97.0-98.8 mol%), AH-22 (degree of saponification: 97.5-98.5 mol%), NH-18 (degree of saponification: 98.0-99. 0 mol%), and N-300 (degree of saponification: 98.0 to 99.0 mol%); for example, JC-33 (degree of saponification: 99.0 mol% or more) of Nippon Vinegar Pival Co., Ltd. , JM-33 (degree of saponification: 93.5 to 95.5 mol%), JM-26 Saponification degree: 95.5-97.5 mol%), JP-45 (saponification degree: 86.5-89.5 mol%), JF-17 (degree of saponification: 98.0-99.0 mol) %), JF-17L (degree of saponification: 98.0 to 99.0 mol%), JF-20 (degree of saponification: 98.0 to 99.0 mol%) and the like. It can be used suitably.

  By forming such a polyvinyl alcohol resin, a polyvinyl alcohol resin layer is formed. The method for forming the polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method, but from the viewpoint of easily obtaining a polarizer layer having a desired thickness, the polyvinyl alcohol-based resin is formed. It is preferable to form a film by applying the above solution on a substrate film.

  Such a polyvinyl alcohol-based resin layer is stretched and oriented together with the base film, and further, 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 not more than 17 times.

  The thickness of the polarizer layer (the thickness of the stretched polyvinyl alcohol-based resin layer) is 10 μm or less, preferably 7 μm or less. By setting the thickness of the polarizer layer to 10 μm or less, a thin polarizing plate can be configured.

  Examples of the dichroic dye used in the polarizer layer include iodine and organic dyes. Examples of 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, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First Orange S, First Black, etc. can be used. One kind of these dichroic substances may be used, or two or more kinds may be used in combination.

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

  The material of the protective film is not particularly limited, but for example, a cyclic polyolefin resin film, a cellulose acetate resin film made of a resin such as triacetyl cellulose or diacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, poly Examples of the film that have been widely used in the art include polyester-based resin films made of a resin such as butylene terephthalate, polycarbonate-based resin films, acrylic-based resin films, and polypropylene-based resin films.

  Examples of the cyclic polyolefin-based resin include appropriate commercial products such as Topas (registered trademark) (manufactured by Ticona), Arton (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (Nippon ZEON ( ZEONEX (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), Apel (registered trademark) (manufactured by Mitsui Chemicals, Inc.) can be suitably used. When such a cyclic polyolefin resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, pre-filmed cyclic polyolefins such as Essina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonoa (registered trademark) film (manufactured by Optes Co., Ltd.), etc. A commercial product of a film made of a resin may be used.

  The cyclic polyolefin resin film may be uniaxially stretched or biaxially stretched. An arbitrary retardation value can be imparted to the cyclic polyolefin-based resin film by stretching. Stretching is usually performed continuously while unwinding the film roll, and is stretched in the heating furnace in the roll traveling direction, the direction perpendicular to the traveling direction, 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 resin to the glass transition temperature + 100 ° C. The draw ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times in one direction.

  Since the cyclic polyolefin resin film generally has poor surface activity, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment is performed on the surface to be bonded to the polarizing film. preferable. Among these, plasma treatment and corona treatment that can be performed relatively easily are preferable.

  Examples of the cellulose acetate-based resin film include commercially available products such as Fujitac (registered trademark) TD80 (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.), and Fujitac (registered trademark). TD80UZ (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD40UZ (Fuji Film Co., Ltd.), KC8UX2M (Konica Minolta Opto Co., Ltd.), KC4UY (Konica Minolta Opto Co., Ltd.) are preferably used. be able to.

  A liquid crystal layer or the like may be formed on the surface of the cellulose acetate-based resin film in order to improve viewing angle characteristics. Moreover, in order to provide a phase difference, what stretched the cellulose acetate type-resin film may be used. The cellulose acetate-based resin film is usually subjected to a saponification treatment in order to improve the adhesiveness with the polarizing film. As the saponification treatment, a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be employed.

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

  The thickness of the protective film is preferably as thin as possible from the demand for thinning, is preferably 90 μm or less, and more preferably 50 μm or less. On the other hand, if it is too thin, the strength is lowered and the processability is poor, and therefore it is preferably 5 μm or more.

<Production method of polarizing plate>
FIG. 1 is a flowchart showing an outline of a method for producing a polarizing plate using the present invention. Among these, the manufacturing method of the light-polarizing laminated film of the present invention includes:
A resin layer forming step (S10) of forming a double-sided laminated film by forming a polyvinyl alcohol-based resin layer on both sides of the base film;
A stretching step (S20) for stretching the double-sided laminated film;
A dyeing step (S30) for forming a polarizer layer by dyeing the polyvinyl alcohol-based resin layer on both sides of the double-sided laminated film after stretching with a dichroic dye and performing a crosslinking treatment in this order. Yes.

Furthermore, in order to produce a polarizing plate etc.,
A cleaning and drying step (S40) for cleaning and drying the double-sided laminated film;
A protective film laminating step (S50) for obtaining a double-sided laminated film or a single-sided laminated film by laminating a protective film on both sides or one side of the double-sided laminated film.
A drying step (S60) for drying the double-sided laminated film or the single-sided laminated film, and
Peeling step of peeling the polarizing plate, the polarizing plate with the base film or the single-sided polarizing laminated film from the double-sided or single-sided laminated film (S70)
Are performed in this order.

  The manufacturing method of the light-polarizing laminated film of this invention forms a polyvinyl alcohol-type resin layer not only on the single side | surface of a base film but on both surfaces. With this manufacturing method, curling of the film that occurs in the manufacturing process of a polarizing plate or the like can be suppressed, and stable production becomes possible.

<Each manufacturing process>
Hereafter, each process of S10-S70 in FIG. 1 is demonstrated in detail.

[Resin Layer Forming Step (S10)]
Here, the double-sided laminated film which consists of a base film and a polyvinyl alcohol-type resin layer is obtained by forming a polyvinyl alcohol-type resin layer on both surfaces of a base film.

  Suitable materials for the base film are as described in the description of the configuration of the polarizing laminated film. In addition, it is preferable to use a base film that can be stretched in a temperature range suitable for stretching a polyvinyl alcohol-based resin.

  It is preferable that the material which comprises the two polyvinyl alcohol-type resin layers formed in both surfaces of a base film is the same material. In the case of different materials, the curl suppression effect may be reduced.

  Since there is a significant difference in the thickness of the resin layers formed on both sides, the curling suppression effect is reduced, so that the polyvinyl alcohol resin layers on both sides of the double-sided laminated film after stretching are preferably as thick as possible, In particular, the difference in thickness between the two resin layers is preferably 3 μm or less. On the other hand, the specific thickness of the resin layer formed in the resin layer forming step (S10) is preferably 3 to 50 μm, and more preferably 5 to 40 μm. If it is 3 μm or less, the film becomes too thin after stretching and the dyeability is remarkably deteriorated. On the other hand, if it exceeds 50 μm, the thickness of the finally obtained polarizer layer may exceed 10 μm, which is not preferable.

  The polyvinyl alcohol-based resin layer is preferably dried by applying a polyvinyl alcohol-based resin solution obtained by dissolving a polyvinyl alcohol-based resin powder in a good solvent onto one surface of the base film and evaporating the solvent. It is formed by doing. By forming the polyvinyl alcohol-based resin layer in this manner, the polyvinyl alcohol-based resin can be thinned. As a method of coating a polyvinyl alcohol resin solution on a base film, a wire bar coating method, a reverse coating, a roll coating method such as gravure coating, a die coating method, a comma coating method, a lip coating method, a spin coating method, a screen A known method such as a coating method, a fountain coating method, a dipping method, or a spray method can be appropriately selected and employed. A drying temperature is 50-200 degreeC, for example, Preferably it is 60-150 degreeC. 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 performed in order one side at a time using the above-described method, or can be performed using a dipping method, a spray coating method, or other special equipment. A polyvinyl alcohol-type resin layer can also be apply | coated to both surfaces of a material film simultaneously.

  Moreover, in order to improve the adhesiveness of a base film and a polyvinyl alcohol-type resin layer, you may provide a primer layer between a base film and a polyvinyl alcohol-type 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. Materials suitable for the primer layer are as described in the description of the configuration of the polarizing plate.

  When providing a primer layer, the order of application to the base film is not particularly limited. After forming the primer layer on both sides of the base film, a polyvinyl alcohol resin layer may be formed on both sides of the primer layer. Alternatively, the primer layer and the polyvinyl alcohol-based resin layer may be sequentially formed on one surface of the base film, and then the primer layer and the resin layer may be sequentially formed on the other surface of the base film.

[Stretching step (S20)]
Here, the double-sided laminated film obtained in the resin layer forming step (S10) is stretched. Preferably, uniaxial stretching is performed so that the stretching ratio is more than 5 times and not more than 17 times. More preferably, it is uniaxially stretched so that the stretch ratio is more than 5 times and not more than 8 times. When the draw ratio 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 high. On the other hand, when the draw ratio exceeds 17 times, the laminated film is liable to break during stretching, and at the same time, the thickness of the laminated film after stretching becomes unnecessarily thin, and the workability and handling properties in the subsequent process are lowered. There is a fear. The stretching process in the stretching step (S20) is not limited to one-stage stretching, and can be performed in multiple stages. In the case of performing in multiple stages, the stretching process is performed so that the stretching ratio is more than 5 times by combining all stages of the stretching process.

  In the stretching step (S20) in the present embodiment, a longitudinal stretching process performed in the longitudinal direction of the laminated film, a lateral stretching process stretching in the width direction, and the like can be performed. Examples of the longitudinal stretching method include an inter-roll stretching method and a compression stretching method, and examples of the transverse stretching method include a tenter method.

  Moreover, it is preferable that the extending | stretching process in this invention is performed using the dry-type extending | stretching method. By stretching the polyvinyl alcohol resin layer together with the base film before the dyeing step, the polyvinyl alcohol resin film (polarizer layer) that is thinner than before can be stretched at a high magnification without breaking. This is because the polarizing plate to be manufactured can be thinned.

[Dyeing step (S30)]
Here, the polyvinyl alcohol-type resin layers on both sides of the double-sided laminated film are dyed with a dichroic dye. Examples of the dichroic dye include iodine and organic dyes. Examples of 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, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First Orange S, First Black, etc. can be used. One kind of these dichroic substances may be used, or two or more kinds may be used in combination.

  A dyeing process is performed by immersing the whole stretched film in the solution (dyeing solution) containing the said dichroic dye, for example. As the staining solution, a solution in which the above dichroic dye is dissolved in a solvent can be used. As a solvent for the dyeing solution, water is generally used, but an organic solvent compatible with water may be further added. The concentration of the dichroic dye is preferably 0.01 to 10% by weight, more preferably 0.02 to 7% by weight, and particularly preferably 0.025 to 5% by weight.

  When iodine is used as the dichroic dye, it is preferable to further add an 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, and iodide. Examples include titanium. The addition ratio of these iodides is preferably 0.01 to 20% by weight in the dyeing solution. Of the 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 in the range of 1: 6 to 1:80 by weight. , Particularly preferably in the range of 1: 7 to 1:70.

  The immersion time of the stretched film in the dyeing solution is not particularly limited, but is usually preferably in the range of 15 seconds to 15 minutes, and more preferably 1 minute to 3 minutes. Moreover, it is preferable that it is in the range of 10-60 degreeC, and, as for the temperature of a dyeing | staining solution, it is more preferable that it exists in the range of 20-40 degreeC.

  In the dyeing step, a crosslinking treatment can be performed after the dyeing. The crosslinking treatment is performed, for example, by immersing the laminated film in a solution containing a crosslinking agent (crosslinking solution). Conventionally known substances can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. One kind of these may be used, or two or more kinds may be used in combination.

  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 can be used, but an organic solvent compatible with water may be further included. Although the density | concentration of the crosslinking agent in a crosslinking solution is not limited to this, It is preferable to exist in the range of 1-20 weight%, and it is more preferable that it is 6-15 weight%.

  Iodide may be added to the crosslinking solution. By adding iodide, the in-plane polarization characteristics 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. Is mentioned. The iodide content 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 usually preferably from 15 seconds to 20 minutes, and more preferably from 30 seconds to 15 minutes. Moreover, it is preferable that the temperature of a crosslinking solution exists in the range of 10-80 degreeC.

  By the above dyeing | staining process (S30), a polyvinyl alcohol-type resin layer will have a function as a polarizer layer, and a double-sided polarizing laminated film is obtained.

[Washing and drying step (S40)]
Next, it is preferable to perform a cleaning process for cleaning the double-sided polarizing laminate film. As the washing step, a water washing treatment can be performed. The water washing treatment can usually be performed by immersing the stretched film in pure water such as ion exchange water or distilled water. The water washing temperature is usually in the range of 3 to 50 ° C, preferably 4 to 20 ° C. The immersion time is usually 2 to 300 seconds, preferably 3 to 240 seconds.

  In the washing step, washing treatment with an iodide solution and water washing treatment may be combined, and a solution in which liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, propanol or the like is appropriately blended may be used. Moreover, you may provide the process of draining using a nip roll, an air knife, etc. after a washing | cleaning process.

  It is preferable to dry the double-sided polarizing laminate film after the washing step. Such drying preferably includes a drying step at a temperature of 60 ° C. or higher, and more preferably includes a drying step at a temperature of 70 ° C. or higher. Of course, a multi-step drying process with different temperatures may be included. In that case, any drying process should just be 60 degreeC or more among multistage drying processes.

  In order to enhance the drying power in addition to the temperature, the hot air circulation method such as the air volume and the wind direction may be optimized, or an IR heater that can apply heat locally may be provided. These aids further improve the efficiency of drying and contribute to productivity improvement.

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

[Protective film pasting step (S50)]
Here, a protective film is bonded to one side or both sides of the double-sided laminated film that has undergone the above steps. As a method of bonding a polarizer layer and a protective film, the method of bonding a polarizer layer and a protective film through an adhesive layer or an adhesive layer is mentioned. Materials suitable as the protective film are as described in the description of the structure of the polarizing plate.

(Adhesive layer)
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is usually a composition in which an acrylic resin, a styrene resin, a silicone resin, or the like is used as a base polymer and a crosslinking agent such as an isocyanate compound, an epoxy compound, or an aziridine compound is added thereto. Become. Furthermore, a pressure-sensitive adhesive layer exhibiting light scattering properties can be formed by mixing fine particles in the pressure-sensitive adhesive.

  The thickness of the pressure-sensitive adhesive layer is preferably 1 to 40 μm, but it is preferably applied thinly, and more preferably 3 to 25 μm, as long as the workability and durability characteristics are not impaired. When it is 3 to 25 μm, it has good processability and is also suitable for suppressing the dimensional change of the polarizing film. When the pressure-sensitive adhesive layer is less than 1 μm, the tackiness is lowered, and when it exceeds 40 μm, problems such as the pressure-sensitive adhesive protruding easily occur.

  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 protective film surface or the polarizer layer surface, After forming the pressure-sensitive adhesive layer by drying, it may be bonded to a separator or other types of film, or after forming the pressure-sensitive adhesive layer on the separator, it is laminated on the protective film surface or the polarizer layer surface. Also good. Further, when forming the pressure-sensitive adhesive layer on the surface of the protective film or the polarizer layer, if necessary, the protective film or the polarizer layer surface, or one or both of the pressure-sensitive adhesive layers may be subjected to an adhesion treatment such as corona treatment. Good.

(Adhesive layer)
Examples of the adhesive constituting the adhesive layer include a water-based adhesive using a polyvinyl alcohol-based resin aqueous solution, a water-based two-component urethane-based emulsion adhesive, and the like. Among these, a polyvinyl alcohol resin aqueous solution is preferably used. Polyvinyl alcohol resins used as adhesives include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as other single quantities copolymerizable with vinyl acetate. And vinyl alcohol copolymers obtained by saponifying the copolymer with the polymer, and modified polyvinyl alcohol polymers obtained by partially modifying the hydroxyl groups. A polyhydric aldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound, or the like may be added as an additive to the water-based adhesive. When such a water-based adhesive is used, the adhesive layer obtained therefrom is usually much thinner than 1 μm, and even when the cross section is observed with a normal optical microscope, the adhesive layer is practically not observed.

  The method of laminating the film using the water-based adhesive is not particularly limited, and the adhesive is evenly applied or poured on the surface of the film, and the other film is laminated on the coated surface and laminated with a roll or the like. And a drying method. Usually, an adhesive agent is apply | coated at the temperature of 15-40 degreeC after the preparation, and the bonding temperature is the range of 15-30 degreeC normally.

  When using a water-system adhesive, after bonding a film, in order to remove the water contained in a water-system adhesive, it is made to dry. The temperature of the drying furnace is preferably 30 ° C to 90 ° C. If it is less than 30 ° C., the adhesive surface tends to be peeled off. If it is 90 ° C. or higher, the optical performance of the polarizer or the like may be deteriorated by heat. The drying time can be 10 to 1000 seconds.

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

  Moreover, a photocurable adhesive can also be used as a non-aqueous adhesive. Examples of the photocurable adhesive include a mixture of a photocurable epoxy resin and a photocationic polymerization initiator.

  As a method of laminating a film with a photocurable adhesive, a conventionally known method can be used. For example, casting method, Mayer bar coating method, gravure coating method, comma coater method, doctor plate method, die coating method Examples of the method include applying an adhesive to the adhesive surface of the film by a dip coating method, a spraying method, and the like, and superimposing two films. The casting method is a method in which two films as an object to be coated are moved in a substantially vertical direction, generally in a horizontal direction, or in an oblique direction between the two, and an adhesive is allowed to flow down and spread on the surface. is there.

  After the adhesive is applied to the surface of the film, it is bonded by sandwiching the film with a nip roll or the like. Moreover, the method of pressing this laminated body with a roll etc. and spreading it uniformly can also be used suitably. In this case, a metal, rubber, or the like can be used as the material of the roll. Furthermore, a method in which this laminate is passed between rolls and pressed to spread is preferably employed. In this case, these rolls may be made of the same material or different materials. The thickness of the adhesive layer after being bonded using the nip roll or the like before drying or curing is preferably 5 μm or less and 0.01 μm or more.

  In order to improve adhesiveness, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment may be appropriately performed on the adhesion surface of the film. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

  When a photocurable resin is used as an adhesive, the photocurable adhesive is cured by irradiating active energy rays after laminating the films. The light source of the 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, the low-pressure mercury lamp, the medium-pressure mercury lamp, the high-pressure mercury lamp, the ultrahigh-pressure mercury lamp, the chemical lamp, and the black light lamp A microwave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW / it is preferable that the cm ^2. When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when it is 6000 mW / cm ² or less, the epoxy is generated by the heat radiated from the light source and the heat generated when the photo-curable adhesive is cured. There is little risk of yellowing of the resin or deterioration of the polarizing film. The light irradiation time to the photocurable adhesive is not particularly limited and is applied according to the photocurable adhesive to be cured, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time. Is preferably set to be 10 to 10,000 mJ / cm ² . When the cumulative amount of light to the photocurable adhesive is 10 mJ / cm ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to allow the curing reaction to proceed more reliably, and at 10,000 mJ / cm ² or less. In some cases, irradiation time does not become too long 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 μm, preferably 0.01 μm or more and 2 μm or less, more preferably 0.01 μm or more and 1 μm or less. .

  When curing a photocurable adhesive of a film containing a polarizer layer or a protective film by irradiation with active energy rays, various polarizing plate properties such as the degree of polarization, transmittance and hue of the polarizer layer, and the transparency of the protective film, etc. It is preferable to perform the curing under conditions where the function does not decrease.

[Drying step (S60)]
In the said protective film bonding process (S50), when the solution containing a solvent is used in order to form an adhesive bond layer or an adhesive layer, drying of a double-sided bonding film or a single-sided bonding film is implemented. In this drying step, the purpose is mainly 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 washing and drying step (S40). In particular, when an aqueous polyvinyl alcohol resin solution or the like is used to form an adhesive layer, it is preferable to perform drying at a temperature of 60 ° C. or higher.

[Peeling step (S70)]
A peeling process (S70) which peels a polarizing plate, a polarizing plate with a substrate film, or a single-sided polarizing laminated film from a double-sided bonding film or a single-sided bonding film is performed after the drying step (S60). The peeling method of a polarizing plate, a polarizing plate with a base film, or a single-sided polarizing laminated film is not particularly limited, and the same method as the peeling film peeling step performed with a normal polarizing plate with an adhesive can be employed. After the drying step (S60), it may be peeled off as it is, or after winding up once in a roll shape, a separate peeling step may be provided for peeling.

[Other optical layers]
The polarizing plate obtained by the present invention can be used as a polarizing plate in which other optical layers are laminated in practical use. Moreover, the said protective film may have a function of these optical layers.

  Examples of other optical layers include a reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties, a film with an antiglare function having an uneven shape on the surface, and a surface antireflection function. Examples thereof include an attached film, a reflective film having a reflective function on the surface, a transflective film having both a reflective function and a transmissive function, and a viewing angle compensation film.

  Commercially available products corresponding to reflective polarizing films that transmit certain types of polarized light and reflect polarized light that exhibits the opposite properties include DBEF (available from 3M, Sumitomo 3M Co., Ltd.), APF (Available from 3M, available from Sumitomo 3M Limited). Examples of the viewing angle compensation film include an optical compensation film coated with a liquid crystal compound on the surface of the substrate and oriented, a retardation film made of a polycarbonate resin, and a retardation film made of a cyclic polyolefin resin. Commercially available products corresponding to an optical compensation film coated with a liquid crystal compound on the substrate surface and oriented are WV film (Fuji Film Co., Ltd.), NH film (Shin Nippon Oil Co., Ltd.), NR Examples include films (manufactured by Nippon Oil Corporation). Commercial products corresponding to retardation films made of cyclic polyolefin resins include Arton (registered trademark) film (manufactured by JSR Corporation), Essina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), Zeonor ( Registered trademark) film (manufactured by Optes Co., Ltd.).

[Example 1]
Manufacturing up to the double-sided polarizing laminate film 302 was performed as shown in the flowchart of FIG.

(Base film)
A homopolymer which is a propylene homopolymer on both sides of a resin layer consisting of a random copolymer of propylene / ethylene containing about 5% by weight of ethylene units (“Sumitomo Nobrene W151” manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 138 ° C.) A base film 1 having a three-layer structure in which a resin layer made of polypropylene (“Sumitomo Nobrene FLX80E4” manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 163 ° C.) is arranged was produced by coextrusion molding using a multilayer extrusion molding machine. . The total thickness of the obtained base film 1 was 90 μm, and the thickness ratio (FLX80E4 / W151 / FLX80E4) of each layer was 3/4/3.

(Primer layer formation process)
Polyvinyl alcohol powder (trade name: Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree 1100, average saponification degree 99.5 mol%) is dissolved in hot water at 95 ° C. and an aqueous solution having a concentration of 3% by weight. Was prepared. The resulting aqueous solution was mixed with 5 parts by weight of a cross-linking agent (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumirez (registered trademark) Resin 650) with respect to 6 parts by weight of the polyvinyl alcohol powder to obtain a primer solution. One side of the substrate film 1 was subjected to corona treatment, and the primer solution was applied using a micro gravure coater and dried at 80 ° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm.

  Furthermore, the other surface of the base film was also subjected to corona treatment, and a similar primer solution coating treatment was performed to produce a film in which a primer layer was formed on both sides of the base film 1.

(Resin layer forming process)
Polyvinyl alcohol powder (trade name: PVA124, manufactured by Kuraray Co., Ltd., average polymerization degree 2400, average saponification degree 98.0-99.0 mol%) is dissolved in 95 ° C. hot water and a concentration of 8 wt% polyvinyl is obtained. An aqueous alcohol solution was prepared. The obtained aqueous solution was applied to the surface of the primer layer formed on one surface of the base film 1 using a lip coater, continuously at 80 ° C. for 2 minutes, at 70 ° C. for 2 minutes, at 60 ° C. It dried for 4 minutes and produced the two-layered single area layer film 201 which consists of the base film 1 and the polyvinyl alcohol-type resin layer 21. As shown in FIG.

  Furthermore, the same coating process is performed on the surface of the primer layer formed on the other surface of the base film 1, and both surfaces comprising the polyvinyl alcohol resin layer 21, the base film 1, and the polyvinyl alcohol resin layer 22. A laminated film 202 was created. The thicknesses of the polyvinyl alcohol-based resin layers 21 and 22 (before stretching) at this time were 10.5 μm and 10.2 μm, respectively.

(Stretching process)
The double-sided laminated film 202 was subjected to 5.8 times free end uniaxial stretching at 160 ° C. using a roll-to-roll longitudinal stretching machine. The thicknesses of the two polyvinyl alcohol-based resin layers of the double-sided laminated film after stretching were 5.1 μm and 4.9 μm, respectively. The double-sided laminated film 202 after stretching was flat with almost no curling, and the handling property in the stretching process was very good.

  Furthermore, although the small piece cut out from the double-sided laminated film after stretching was left for 5 days in an environment of 23 ° C. and 50% RH, it did not generate any curl and maintained a good shape.

(Dyeing process)
The stretched double-sided laminated film is immersed in a 60 ° C. warm bath for 60 seconds, and then immersed in a dyeing solution that is a mixed aqueous solution of iodine and potassium iodide at 30 ° C. for about 150 seconds. Excess iodine solution was washed away with water. Subsequently, it was immersed for 600 second in the bridge | crosslinking solution which is a 76 degreeC mixed aqueous solution of boric acid and potassium iodide.

(Washing and drying process)
Thereafter, the double-sided laminated film was washed with pure water at 10 ° C. for 4 seconds, and finally dried at 80 ° C. for 300 seconds. Through the above steps, the polyvinyl alcohol-based resin layers 21 and 22 formed on both surfaces of the base film 1 were used as the polarizer layers 31 and 32, and a double-sided polarizing laminate film 302 was obtained. During this drying, curling hardly occurred and a double-sided polarizing laminate film could be continuously formed in a good state.

The mixing ratio of the dyeing solution and the crosslinking solution is
<Dyeing solution>
Water: 100 parts by weight Iodine: 0.6 parts by weight Potassium iodide: 10 parts by weight <Crosslinking solution>
Water: 100 parts both parts Boric acid: 9.5 parts by weight Potassium iodide: 5 parts by weight

[Example 2]
Production from the double-sided polarizing laminate film 302 to the polarizing plates 501a and 501b was performed as shown in the flowchart of FIG.

(Protective film bonding process)
Polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree 1800, trade name: KL-318) was dissolved in 95 ° C. hot water to prepare an aqueous solution having a concentration of 3% by weight. The resulting aqueous solution was mixed with 1 part by weight of a crosslinking agent (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumirez (registered trademark) Resin 650) with respect to 2 parts by weight of polyvinyl alcohol powder to obtain an adhesive solution. After applying the above-mentioned polyvinyl alcohol-based adhesive on both sides of the double-sided polarizing laminate film 302 obtained in Example 1, protective films 41 and 42 (TAC: KC4UY manufactured by Konica Minolta Opto Co., Ltd.) were bonded, and 80 The double-sided bonding film 402 which consists of five layers, the protective film 41, the polarizer layer 31, the base film 1, the polarizer layer 42, and the protective film 42 was obtained by making it dry at 5 degreeC.

(Drying process and peeling process)
From the double-sided bonding film 402, the polarizing plate 501a composed of the polarizer 31 and the protective film 41 was peeled off. The base film was peeled from the remaining film (the film made of the base film 1, the polarizer layer 32, and the protective film 42) to obtain a polarizing plate 501b made of the polarizer 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 surfaces thereof. The thicknesses of the polarizer layers 31 and 32 of the two polarizing plates 501a and 501b thus obtained were both 5.0 μm.

[Example 3]
A double-sided laminated film was obtained in the same manner as Example 1. The thicknesses of the polyvinyl alcohol resin layers 21 and 22 (before stretching) at this time were 25.2 μm and 28.7 μm, respectively. This double-sided laminated film was stretched uniaxially at 5.8 times at 160 ° C. using a tenter stretching device to obtain a stretched film. The thickness of the stretched polyvinyl alcohol resin layer was 4.6 μm and 4.9 μm, respectively. The double-sided laminated film 202 after stretching was flat with almost no curling, and the handling property in the stretching process was very good.

  Furthermore, although the small piece cut out from the double-sided laminated film after stretching was allowed to stand for 5 days in an environment of 23 ° C. and 50% RH, no curling occurred and the good shape was maintained.

  Thereafter, the stretched double-sided laminated film was dyed in the same manner as in Example 1. However, curling hardly occurred during drying after dyeing, and a double-sided polarizing laminated film was continuously produced in a good shape. We were able to.

[Example 4]
As shown in the flowchart of FIG. 3, a double-sided polarizing laminate film was obtained by the same method as in Example 1. Thereafter, the protective film 41 is bonded to only one side of the double-sided polarizing laminate film 302 and dried in the same manner as in Example 2, so that the protective film 41 / polarizer layer 31 / substrate film 1 / polarizer is dried. A single-sided bonding film 401 consisting of four layers 32 was obtained.

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

[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 provided only on one side of the base film. Since the resin layer was formed only on one side, the obtained film was easily curled and lacked handling properties. Further, when the obtained film was left in an environment of 23 ° C. and 50% RH, the curl further increased. In addition, the film manufactured by such a conventional method can be used without any problem as long as it is on the production line and is in a tensioned state. Since it becomes difficult to use, it is not suitable for the case of wanting to include a winding process once for the convenience of the production line.

  Next, this stretched film was dyed by the same dyeing process as in Example 1 to obtain a polarizing laminated film. However, during drying, significant curling occurred so that the film could not be conveyed, and the end of the film was There was a problem of folding inside. For this reason, a polarizing laminated film could not be obtained continuously and stably.

  DESCRIPTION OF SYMBOLS 1 Base film, 21, 22 Polyvinyl alcohol-type resin layer, 201 Single area layer film, 202 Double-sided laminated film, 31,32 Polarizer layer, 302 Double-sided polarizing laminated film, 41,42 Protective film, 401 Single-sided bonding film, 402 Double-sided laminated film, 501, 501a, 501b Polarizing plate, 601 Single-sided polarizing laminate film.

Claims (11)

A method for producing a double-sided polarizing laminate film comprising a base film and a polarizer layer formed on both sides of the base film,
A resin layer forming step of obtaining a double-sided laminated film by forming a polyvinyl alcohol-based resin layer on both sides of the base film;
A stretching step of stretching the double-sided laminated film;
A double-sided polarizability comprising, in this order, a dyeing step of forming a polarizer layer by dyeing the polyvinyl alcohol-based resin layer on both sides of the double-sided laminated film after stretching with a dichroic dye and performing a crosslinking treatment A method for producing a laminated film.   The manufacturing method of the double-sided polarizing laminated film of Claim 1 whose material which comprises the polyvinyl alcohol-type resin layer of both surfaces of the said double-sided laminated film is the same material.   The manufacturing method of the double-sided polarizing laminated film of Claim 1 or 2 whose difference of the thickness of the polyvinyl alcohol-type resin layer in both surfaces of the said double-sided laminated film after extending | stretching is 3 micrometers or less.   The method for producing a double-sided polarizing laminate film according to any one of claims 1 to 3, wherein in the stretching step, the film is stretched at a stretch ratio of more than 5 times. The manufacturing method of the double-sided polarizing laminated film in any one of Claims 1-4 whose thickness of each polarizer layer of both surfaces of the said double-sided polarizing laminated film is 10 micrometers or less. A method for producing a polarizing plate comprising a polarizer layer and a protective film formed on one surface of the polarizer layer,
A protective film laminating step for laminating a protective film on both sides of the double-sided polarizing laminate film obtained by the production method according to claim 1,
The manufacturing method of a polarizing plate including the peeling process which peels at least 1 piece of the said polarizing plate from the said double-sided bonding film in this order.   The manufacturing method of the polarizing plate of Claim 6 which peels simultaneously the two polarizing plates of the both surfaces of the said double-sided bonding film in the said peeling process.   The manufacturing method of the polarizing plate of Claim 6 which peels the polarizing plate of the one surface of the said double-sided bonding film in the said peeling process, and then peels the polarizing plate of the other surface. In the manufacturing method of a polarizing plate with a base film 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 There,
A protective film laminating step for laminating a protective film on both sides of the double-sided polarizing laminate film obtained by the production method according to claim 1,
The manufacturing method of the polarizing plate with a base film which includes the peeling process which peels off the said polarizing plate with a base film from the said double-sided bonding film in this order. A method for producing a polarizing plate comprising a polarizer layer and a protective film formed on one surface of the polarizer layer,
A protective film laminating step of laminating a protective film on one surface of the double-sided polarizing laminate film obtained by the production method according to claim 1 and obtaining a single-sided laminating film;
The manufacturing method of a polarizing plate including the peeling process which peels the said polarizing plate from the said single-sided bonding film in this order. A production method of a base film, and a single-sided polarizing laminate film comprising a polarizer layer formed on one surface of the base film,
A protective film laminating step of laminating a protective film on one surface of the double-sided polarizing laminate film obtained by the production method according to claim 1 and obtaining a single-sided laminating film;
The manufacturing method of the single-sided polarizing laminated film which includes the peeling process which peels off the said single-sided polarizing laminated film from the said single-sided bonding film in this order.

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