JP2012123229A - Manufacturing method of polarizing laminate film and polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart, in a manufacturing method of polarizing laminate film where a polyvinyl alcohol resin layer as a polarizer layer is mounted on the surface of a base film and then the base film with the polyvinyl alcohol resin layer is stretched, followed by dyeing treatment and crosslinking treatment, water resistance to a primer layer used to enhance adhesion of the base film with the polyvinyl alcohol resin layer so that the polyvinyl alcohol resin layer does not detach from the base material during immersion in a dyeing solution or a crosslinking solution.SOLUTION: The present invention is a manufacturing method of polarizing laminate film comprising a base film, a primer layer and a polarizer layer in this order, and characterized in that a primer solution used to enhance adhesion of the base film and the polyvinyl alcohol resin layer contains at least one kind of crosslinking agent selected from the group consisting of a dialdehyde-based crosslinking agent, an isocyanate-based crosslinking agent and a metal-based crosslinking agent.

Description

  The present invention relates to a polarizing laminate film and a method for producing a polarizing plate.

  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 polyvinyl alcohol (PVA) resin and a protective film made of triacetyl cellulose (TAC) are conventionally used as a polarizing plate. With the development of devices such as notebook personal computers and mobile phones, reduction in thickness and weight is required.

  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 used as a polarizer layer on the surface of a base film, the polyvinyl alcohol-type resin layer is dry-stretched with the base film, dyeing | staining processing and a crosslinking process are given, and polyvinyl alcohol-type resin By making the layer a polarizer layer, the total thickness of the base film and the polarizer layer can be reduced to the limit, and the thickness of the polarizer layer (polarizing film) can be made thinner than before. Has been proposed (see, for example, Patent Document 1).

  However, the adhesion between the base film and the polyvinyl alcohol resin layer is not strong, and the polyvinyl alcohol resin layer is removed from the base film at the time of stretching in the stretching process or when immersed in a dyeing solution and a crosslinking solution in the dyeing process. The problem of peeling off is considered.

  As a method for improving the adhesion between the base film and the polyvinyl alcohol resin layer, a primer solution is applied on the base film to form a primer layer, and then the polyvinyl alcohol resin layer is formed on the primer layer. A method of forming is conceivable. Here, the primer solution is preferably an aqueous solution in terms of suppressing damage to the base film, and therefore, an aqueous solution of a water-soluble polymer is preferably used as the primer solution. In this case, since a primer layer generally formed from an aqueous solution of a water-soluble polymer has low water resistance, the polyvinyl alcohol resin layer may be peeled off from the base film in the dipping process in a staining solution or a crosslinking solution.

JP 2000-338329 A

  The present invention provides a polarizing laminated film in which a polyvinyl alcohol-based resin layer serving as a polarizer layer is provided on the surface of a base film, and then the polyvinyl alcohol-based resin layer is stretched together with the base film and subjected to a dyeing process and a crosslinking process. In the production method, the primer layer used for improving the adhesion between the base film and the polyvinyl alcohol resin layer is not peeled off from the base material even when immersed in a dyeing solution or a crosslinking solution. The purpose is to provide excellent water resistance.

The present invention is a primer layer forming step of forming a primer layer by applying a primer solution on one surface of a base film;
Forming a polyvinyl alcohol-based resin layer on the primer layer, and obtaining a laminated film including the base film, the primer layer, and the polyvinyl alcohol-based resin layer in this order; and a polyvinyl alcohol-based resin layer forming step;
A stretching step of stretching the laminated film;
A dyeing step of dyeing the polyvinyl alcohol-based resin layer of the laminated film with a dichroic dye to form a polarizer layer in this order,
A method for producing a polarizing laminated film comprising the base film, the primer layer and the polarizer layer in this order,
The primer solution includes at least one crosslinking agent selected from the group consisting of a dialdehyde crosslinking agent, an isocyanate crosslinking agent, and a metal crosslinking agent. .

Furthermore, the primer solution preferably contains a water-soluble polymer.
The water-soluble polymer is preferably a polyvinyl alcohol resin.

The solvent of the primer solution is preferably a solvent containing water.
The crosslinking agent is preferably water-soluble or water-dispersible.

The dialdehyde-based crosslinking agent is preferably glyoxal.
The isocyanate-based crosslinking agent is preferably a polyisocyanate having at least one isocyanate group in one molecule.

The metal-based crosslinking agent is preferably an organometallic compound.
The organometallic compound is preferably a chelate complex.

  The thickness of the primer layer before the stretching step is preferably 0.05 to 1.0 μm.

  It is preferable that the thickness before the said extending process of the said polyvinyl alcohol-type resin layer is 3-30 micrometers.

The thickness of the polarizer layer 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 of laminating a protective film on the surface opposite to the surface on the base film side of the polarizing laminated film obtained by the method for producing a polarizing laminated film;
A base film peeling process for peeling the base film from the polarizing laminated film;
Are also included in this order.

  In this invention, after providing the polyvinyl alcohol-type resin layer used as a polarizer layer on the surface of a base film, the polyvinyl alcohol-type resin layer is extended | stretched with the base film, and the polarizing laminated film which performs a dyeing process and a crosslinking process In the production method, by providing water resistance to the primer layer used for enhancing the adhesion between the base film and the polyvinyl alcohol-based resin layer, the polyvinyl alcohol-based resin layer at the time of immersion in a dyeing solution or a crosslinking solution is added. Peeling from the substrate is prevented.

It is a flowchart which shows one Embodiment of the manufacturing method of the light-polarizing laminated film of this invention. It is a flowchart which shows one Embodiment of the manufacturing method of the polarizing plate of this invention.

  In the present specification, a laminate in which a polyvinyl alcohol (PVA) resin layer is laminated on one surface of a base film via a primer layer is referred to as a “laminated film”. Moreover, the polyvinyl alcohol-type resin layer (layer which consists of polyvinyl alcohol-type resin) which has a function as a polarizer is called "polarizer layer", and the laminated body provided with the polarizer layer on one side of the base film is " It is called “polarizing laminated 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. Among these, polyolefin resins are particularly preferably used.

  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. The polyvalent carboxylic acid used is mainly a divalent dicarboxylic acid, 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. The cyclic polyolefin resin is a general term for resins that are polymerized using a 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.

  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.

  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 primer layer is formed in order to further improve the adhesion with the polyvinyl alcohol resin layer.

[Primer layer]
A primer layer is formed on the surface of the base film on the side where the polarizer layer is formed in order to improve the adhesion between the base film and the polyvinyl alcohol resin layer.

(Thermoplastic resin)
The main material which comprises a primer layer will not be specifically limited if it is the material which exhibits a certain amount of strong adhesive force to both a base film and a polyvinyl alcohol-type resin layer. For example, a thermoplastic resin excellent in transparency, heat stability, stretchability, etc. is used. Examples of the thermoplastic resin include, but are not limited to, an acrylic resin and a polyvinyl alcohol resin. Of these, polyvinyl alcohol resins having good adhesion are 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.

(Crosslinking agent)
In the present invention, in order to improve the water resistance of the primer layer, the primer solution contains at least one crosslinking agent selected from the group consisting of a dialdehyde crosslinking agent, an isocyanate crosslinking agent and a metal crosslinking agent. Added.

  Examples of the isocyanate-based crosslinking agent include tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane triisocyanate, isophorone diisocyanate, and these Isocyanates such as a ketoxime block product or a phenol block product.

Examples of the dialdehyde-based crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleidialdehyde, phthaldialdehyde, etc. Examples of the metal-based crosslinking agent include metal salts and metal oxides. , Metal hydroxides, and organometallic compounds. The type of metal is not particularly limited and may be selected as appropriate.

  Examples of metal salts, metal oxides, and metal hydroxides include sodium, potassium, magnesium, calcium, aluminum, iron, nickel, zirconium, titanium, silicon, boron, zinc, copper, vanadium, chromium, and tin. Examples thereof include metal salts having a valence higher than the valence, oxides thereof, and hydroxides.

  An organometallic compound is a compound having in the molecule at least one structure in which an organic group is bonded directly to a metal atom or an organic group is bonded through an oxygen atom, a nitrogen atom, or the like. The organic group means a functional group containing at least a carbon element, and can be, for example, an alkyl group, an alkoxy group, an acyl group, or the like. The bond does not mean only a covalent bond, but may be a coordinate bond by coordination of a chelate compound or the like. The metal constituting the organometallic compound is preferably titanium, zirconium, aluminum, or silicon, and more preferably titanium or zirconium. That is, preferable examples of the organometallic compound include a titanium organic compound, a zirconium organic compound, an aluminum organic compound, and a silicon organic compound. Only one kind of these metal organic compounds may be used, or two or more kinds may be appropriately mixed and used.

  Specific examples of the titanium organic compound include, for example, titanium orthoesters such as tetranormal butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, tetramethyl titanate; titanium acetylacetonate, titanium tetraacetyl Examples include titanium chelates such as acetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate, titanium triethanolamate, titanium ethylacetoacetate; titanium acylates such as polyhydroxytitanium stearate; .

  Specific examples of the zirconium organic compound include, for example, zirconium normal propyrate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium acetylacetonate bisethylacetoacetate and the like. It is done.

  Specific examples of the aluminum organic compound include aluminum acetylacetonate and aluminum organic acid chelate.

  Specific examples of the silicon organic compound include compounds having the ligands exemplified in the above-described titanium organic compound and zirconium organic compound.

  What is necessary is just to select a more suitable thing for a crosslinking agent suitably according to the thermoplastic resin to be used from these.

  The ratio of the thermoplastic resin and the crosslinking agent used for forming the primer layer is from about 0.1 to 100 parts by weight of the crosslinking agent with respect to 100 parts by weight of the thermoplastic resin. It may be appropriately determined depending on the type of the material, and it is particularly preferable to select from the range of about 0.1 to 50 parts by weight.

(solvent)
The primer solution for forming the primer layer is preferably used in a state dissolved in a solvent. As the solvent, it is preferable to use a solvent having low reactivity with the base film in consideration of the solubility of the base film. Among these, a primer solution in which a polyvinyl alcohol resin having good adhesion is dissolved in water can be preferably used.

  The primer solution preferably has a solid content concentration of about 1 to 25% by weight.

  The thickness of the primer layer (before the stretching step) is preferably 0.05 to 1 μm, more preferably 0.1 to 0.4 μm. 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 uniaxially 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%. If the degree of saponification is less than 80.0 mol%, there is a problem that the water resistance and heat-and-moisture resistance after making a polarizing plate are significantly 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 mol%. 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 Poval Co. , 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 laminated film can be formed.

  Examples of the dichroic dye used for 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.

[Other optical layers]
In practical use, the polarizing plate can be used as a polarizing plate in which other optical layers are laminated. 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.).

<Method for producing polarizing laminated film>
FIG. 1 is a flowchart showing an embodiment of a method for producing a polarizing laminated film. As FIG. 1 shows, the manufacturing method of a polarizing laminated film is as follows.
A primer layer forming step (S10) for forming a primer layer by applying a primer solution to one surface of the base film;
A polyvinyl alcohol-based resin layer forming step (S20) in which a polyvinyl alcohol-based resin layer is formed on the primer layer to obtain a laminated film including the base film, the primer layer, and the polyvinyl alcohol-based resin layer in this order. )When,
A stretching step (S30) for stretching the laminated film;
The dyeing step (S40) in which the polyvinyl alcohol-based resin layer of the laminated film is dyed with a dichroic dye to form a polarizer layer is performed in this order.

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

<Production method of polarizing plate>
FIG. 2 is a flowchart showing an embodiment of a method for producing a polarizing plate. As shown in FIG. 2, the manufacturing method of the polarizing plate is
Steps (S10 to S40) similar to the method for producing the polarizing laminated film,
A protective film laminating step (S50) for laminating a protective film on the surface opposite to the surface on the base film side of the polarizing laminated film;
The base film peeling process (S60) which peels the said base film from a light-polarizing laminated film is provided in this order.

  The polarizing plate obtained by this manufacturing method becomes a polarizing plate provided with a polarizer layer having a thickness of 10 μm or less on a protective film. This polarizing plate can be used by, for example, bonding to another optical film or a liquid crystal cell via a pressure-sensitive adhesive.

<Each manufacturing process>
Hereafter, each process of S10-S60 in FIG. 1 and FIG. 2 is demonstrated in detail. Each process of S10 to S40 in FIGS. 1 and 2 is the same process.

[Primer layer forming step (S10)]
Here, a primer layer is formed on one surface of the base film.

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

  The thickness (before the stretching step) of the primer layer formed on the base film is preferably 0.05 to 1 μm. 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.

  The primer layer is preferably formed by applying a primer solution obtained by dissolving a powder of polyvinyl alcohol resin and a crosslinking agent in a solvent onto one surface of the base film and evaporating the solvent to dry the primer layer. It is formed. The composition of the primer solution is as described above.

  In order to improve the adhesion between the substrate film and the primer layer, the substrate film may be subjected to treatment for improving adhesion such as corona treatment, plasma treatment, flame treatment and the like.

  As a method of applying the primer solution to the base film, roll coating methods such as wire bar coating method, reverse coating and gravure coating, die coating method, comma coating method, lip coating method, spin coating method, screen coating method, fountain A coating method, a dipping method, a spray method, and the like can be appropriately selected from known methods and employed.

  A drying temperature becomes like this. Preferably it is 50-200 degreeC, More preferably, it is 60-150 degreeC. The drying time is preferably 1 to 30 minutes, more preferably 2 to 20 minutes, for example. In particular, when the solvent of the primer solution is water, the drying temperature is preferably 50 to 200 ° C., and the drying time is preferably 1 to 60 minutes.

[PVA-based resin layer forming step (S20)]
Here, a resin layer made of a polyvinyl alcohol-based resin is formed on the surface of the primer layer. Thereby, the laminated | multilayer film by which a polyvinyl alcohol-type resin layer is laminated | stacked on a base film through a primer layer are obtained.

  The thickness (before stretching) of the polyvinyl alcohol-based resin layer to be formed is preferably greater than 3 μm and 30 μm or less, and more preferably 5 to 20 μm. If it is 3 μm or less, it becomes too thin after stretching and the dyeability is remarkably deteriorated. If it exceeds 30 μm, the thickness of the finally obtained polarizer layer may exceed 10 μm.

  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.

[Stretching step (S30)]
Here, a laminated film composed of a base film and a polyvinyl alcohol-based resin layer is stretched. Preferably, uniaxial stretching is performed so that the stretching ratio is greater than 5 times and 17 times or less. More preferably, it is uniaxially stretched so that the stretch ratio is greater than 5 times and 8 times or less. 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 (S30) is not limited to one-stage stretching, and can be performed in multiple stages. When performing in multiple stages, the stretching process is performed so that the stretching ratio is greater than 5 times by combining all stages of the stretching process.

  In the stretching step (S30) 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.

  In addition, as the stretching treatment, either a wet stretching method or a dry stretching method can be adopted, but the use of the dry stretching method is preferable because the temperature at which the laminated film is stretched can be selected from a wide range.

[Dyeing step (S40)]
Here, the polyvinyl alcohol resin layer of the stretched film is 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 process, a crosslinking treatment can be performed after dyeing. The crosslinking treatment can be performed, for example, by immersing the stretched 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 polyvinyl alcohol-based resin layer can be made more uniform. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. 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 (S40), a polyvinyl alcohol-type resin layer has a function as a polarizer layer. In this specification, the polyvinyl alcohol-type resin layer which has a function as a polarizer is called a polarizer layer, and the laminated body provided with the polarizer layer on the base film is called a polarizing laminated film.

  Finally, it is preferable to perform a washing step and a drying step. 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.

  It is preferable to perform a drying process after the washing process. Any appropriate method (for example, natural drying, blow drying, heat drying) can be adopted as the drying step. For example, the drying temperature in the case of heat drying is usually 20 to 95 ° C., and the drying time is usually about 1 to 15 minutes. In addition, you may provide the process of draining using a nip roll, an air knife, etc. after a washing | cleaning process.

[Protective film pasting step (S50)]
Here, a protective film is bonded to the surface on the opposite side to the surface on the base film side of the polarizer layer of the polarizing laminate film obtained through 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 protective film or polarizer layer surface, if necessary, the protective film or polarizer layer surface, or one or both of the pressure-sensitive adhesive layers may be subjected to 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 for about 12 to 600 hours at room temperature or slightly higher temperature, for example, about 20 to 45 ° C. 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, a casting method, a Meyer bar coating method, a gravure coating method, a comma coater method, a doctor plate method, a 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.

[Substrate film peeling step (S60)]
After the protective film bonding step (S50), a base film peeling step (S60) for peeling the base film from the polarizing laminated film is performed. The peeling method of a base film is not specifically limited, The method similar to the peeling film peeling process performed with a normal polarizing plate with an adhesive can be employ | adopted. After the protective film laminating step (S50), it may be peeled off as it is, or after it is wound up in a roll shape, it may be peeled off by providing another peeling step.

[Example 1]
According to the manufacturing method shown in FIG. 1, the stretching process (S30) in producing the polarizing laminated film was performed.

(Primer layer formation process)
(1) Base film An unstretched homopolypropylene film having a thickness of 100 μm was used as the base film.

(2) Preparation of primer solution As a crosslinking agent to be added to the primer solution, “Orgatics TC-310 (trade name)” (Matsumoto Pharmaceutical Co., Ltd.), which is an organometallic compound (titanium complex). Active ingredient (chemical structure) : (HO) ₂ Ti [OCH (CH ₃ ) COOH] ₂ ) 44%, isopropyl alcohol 40% and water 16% solution).

  First, water, isopropyl alcohol, and “Orgatics TC-310” were mixed so that the weight ratio of water: isopropyl alcohol: TC-310 was 85: 15: 7.5 to prepare Solution A. Here, the weight ratio of TC-310 means the weight of the entire solution containing the organometallic compound.

  Separately, an aqueous polyvinyl alcohol solution (solution) in which 15 parts of polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., degree of saponification: about 80 mol%, trade name: KL506) is dissolved in 100 parts by weight of water in water at 80 ° C. B) was prepared.

  Solution A and Solution B were mixed so that the weight ratio of Solution A: Solution B was 1.3: 4 to prepare a primer solution.

(3) Formation of primer layer The obtained primer solution was applied on a corona-treated substrate film and dried at 80 ° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm.

(PVA-based resin layer forming step)
Polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree 2400, average saponification degree 98 to 99 mol%) was dissolved in 95 ° C. hot water to prepare a polyvinyl alcohol aqueous solution having a concentration of 8% by weight. The obtained polyvinyl alcohol aqueous solution is coated on the primer layer, dried at 80 ° C. for 20 minutes, and a laminated film in which the base film, the primer layer, and the polyvinyl alcohol-based resin layer are laminated in this order is obtained. Produced. The thickness (before stretching) of the polyvinyl alcohol-based resin layer at this time was 15 μm.

(Stretching process)
The obtained laminated film was stretched 5.5 times in the longitudinal uniaxial direction with a tenter stretching machine. The thickness of the stretched polyvinyl alcohol resin layer was 7.6 μm.

(Dyeing process)
The stretched laminated film is immersed in a 60 ° C. warm bath for 60 seconds, and then a dyeing solution, which is a mixed aqueous solution of iodine and potassium iodide at 30 ° C. (iodine 0.3 parts by weight, iodine After immersing in 5 parts by weight of potassium halide for 300 seconds, excess iodine solution was washed away with pure water at 10 ° C. Subsequently, it was immersed for 300 seconds in the bridge | crosslinking solution (8 weight part of boric acid, 5 weight part of potassium iodide with respect to 100 weight part of water) which is 76 degreeC mixed aqueous solution of boric acid and potassium iodide. Thereafter, the film was washed with pure water at 10 ° C. for 4 seconds and dried at 50 ° C. for 300 seconds to obtain a polarizing laminated film.

(Protective film bonding process)
A protective film (Konica Minolta Opto) using an adhesive made of triacetyl cellulose (TAC) and polyvinyl alcohol (PVA) on the polarizer side of the polarizing laminate film (surface opposite to the polarizer base film). TAC manufactured by KK: KC4UY, thickness 40 μm) was bonded and dried at 80 ° C. for 5 minutes to obtain a polarizing laminated film with a protective film having a base film and a protective film.

  As the polyvinyl alcohol-based adhesive, polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree 1800, trade name: KL-318) is dissolved in 95 ° C. hot water to prepare an aqueous solution having a concentration of 3% by weight, To the obtained aqueous solution, 1 part by weight of a crosslinking agent solution (manufactured by Sumika Chemtex Co., Ltd., trade name: Sumirez (registered trademark) Resin 650) is mixed with 2 parts by weight of polyvinyl alcohol powder to obtain an adhesive solution. What was done was used.

(Base film peeling process)
The base film was peeled off by hand. The base film was easily peeled off to obtain a polarizing plate comprising four layers of a protective film, an adhesive layer, a polarizer layer, and a primer layer. The thickness of the polarizer layer in the obtained polarizing plate was 7.4 μm similarly to the thickness of the polarizer layer in the polarizing laminate film.

  In the above steps, the polyvinyl alcohol resin layer does not peel from the base film when immersed in the dyeing solution or the crosslinking solution, and there is no particular problem when the base film is peeled off. Manufacture was possible.

[Example 2]
In the preparation of the solution A of Example 1, as a crosslinking agent, “Orgatics ZB-400” (manufactured by Matsumoto Pharmaceutical Co., Ltd.), which is an organometallic compound (water-soluble organozirconium compound), 30% by weight of active ingredient and water A primer solution was prepared in the same manner as in Example 1 except that the weight ratio of water: isopropyl alcohol: ZB-400 was 85: 15: 1.

  Other than that was carried out similarly to Example 1, and produced the laminated | multilayer film by which a base film, a primer layer, and a polyvinyl alcohol-type resin layer were laminated | stacked in this order. The thickness (before stretching) of the polyvinyl alcohol-based resin layer at this time was 15 μm. A polarizing plate was produced in the same manner as in Example 1 using the obtained laminated film. The thickness of the polarizer layer was 7.2 μm.

  Also in this example, the polyvinyl alcohol resin layer was not peeled off from the base film when immersed in the dyeing solution or the crosslinking solution, and there was no particular problem when the base film was peeled off. Could be manufactured.

[Example 3]
As the crosslinking agent, a water-dispersible polyisocyanate-based crosslinking agent (Dainippon Ink Chemical Co., Ltd., trade name: Vernock DWN-5000, diethylene glycol dimethyl ether solution having a solid concentration of about 80%) was used.

  While water is heated to 80 ° C., it is mixed with polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., degree of saponification: about 80%, trade name PVA-403), stirred, cooled to room temperature, and further water-dispersible polyisocyanate. A crosslinking agent was added and stirred to prepare a primer solution. In addition, the compounding quantity of the crosslinking agent was 5 weight part with respect to 15 weight part of polyvinyl alcohol powder. Here, the weight of the polyisocyanate crosslinking agent means the weight of the entire solution including the solvent.

  A laminated film in which a base film, a primer layer, and a polyvinyl alcohol-based resin layer were laminated in this order was produced in the same manner as Example 1 except for the preparation of the primer solution. The thickness (before stretching) of the polyvinyl alcohol-based resin layer at this time was 15 μm. A polarizing plate was produced in the same manner as in Example 1 using the obtained laminated film. The thickness of the polarizer layer was 7.5 μm.

  Also in this example, the polyvinyl alcohol resin layer was not peeled off from the base film when immersed in the dyeing solution or the crosslinking solution, and there was no particular problem when the base film was peeled off. Could be manufactured.

[Example 4]
Completely saponified PVA (average polymerization degree of about 1700, saponification degree of 99.6% or more) is dissolved in 95 ° C. water to prepare a 3% by weight aqueous solution, cooled to room temperature, and then dioxal, a dialdehyde-based crosslinking agent. Was added and stirred to prepare a primer solution so that the weight ratio of completely saponified PVA: water: glyoxal was 5: 100: 0.6.

  Other than that was carried out similarly to Example 1, and produced the laminated | multilayer film by which a base film, a primer layer, and a polyvinyl alcohol-type resin layer were laminated | stacked in this order. The thickness (before stretching) of the polyvinyl alcohol-based resin layer at this time was 16 μm. A polarizing plate was produced in the same manner as in Example 1 using the obtained laminated film. The thickness of the polarizer layer was 7.8 μm.

  Also in this example, the polyvinyl alcohol resin layer was not peeled off from the base film when immersed in the dyeing solution or the crosslinking solution, and there was no particular problem when the base film was peeled off. Could be manufactured.

[Comparative Example 1]
Except for using “Smileys Resin 650 (30)” (trade name, aqueous solution with a solid content of 30%), which is a polyamide epoxy resin sold by Sumika Chemtex Co., Ltd., as a crosslinking agent. In the same manner as in Example 1, a laminated film in which a base film, a primer layer, and a polyvinyl alcohol-based resin layer were laminated in this order was produced.

<Warm water resistance test>
In preparation of the light-polarizing laminated film in Examples 1 to 4 and Comparative Example 1, for each of the laminated films in the state after the stretching process (before the dyeing process), a pressure-sensitive adhesive (acrylic) on the surface on the polyvinyl alcohol resin layer side. System adhesive). The laminated film was cut out in a size of 60 mm in the direction of the drawing axis and 35 mm in a direction perpendicular to the drawing axis, and a glass plate was bonded to the pressure-sensitive adhesive side to obtain a sample for a warm water resistance test. The sample was immersed in warm water at 60 ° C., and after 60 minutes, the amount of peeling of the base film from the polyvinyl alcohol-based resin layer was measured. The results are shown in Table 1.

  As Table 1 showed, about the laminated | multilayer film of Examples 1-4, peeling of the base film by warm water immersion was hardly seen. From this, it is understood that a polarizing laminated film can be produced without problems such as peeling even when immersed in a dyeing solution or a crosslinking solution. On the other hand, about the laminated | multilayer film of the comparative example 1, peeling of the base film by warm water immersion was seen clearly.

  From this result, according to the invention of the present application, after providing a polyvinyl alcohol-based resin layer serving as a polarizer layer on the surface of the base film, the polyvinyl alcohol-based resin layer is stretched together with the base film, and dyeing treatment and cross-linking treatment are performed. It can be seen that in the method for producing a polarizing laminated film, the primer layer used for improving the adhesion between the base film and the polyvinyl alcohol-based resin layer can be imparted with water resistance. Thereby, the peeling from the base film of the polyvinyl alcohol-type resin layer in the immersion process to a dyeing solution or a crosslinking solution can be prevented.

<Blocking experiment>
In the production of the laminated films in Examples 1 to 4 and Comparative Example 1, the following experiment was performed on the base film in which only the primer layer was formed, and the degree of blocking was confirmed. The results are shown in Table 1.
(1) A film coated with a primer layer having a size of 300 mm × 220 mm or more is prepared.
(2) The primer coating film is overlapped so that the primer coating surface and the base film (PP) surface are in contact with each other.
(3) The stacked films are sandwiched between 300 mm × 220 mm glasses, put a weight of 2 kg, and put into an oven at 40 ° C.
(4) After 9 days, the film is peeled off, and the proportion of the blocking portion at 100 mm × 100 mm is evaluated as a percentage.

In Examples 1-4, it turns out that blocking does not generate | occur | produce, even when a winding process is once performed about the base film in the state in which only the primer layer was formed.
The

  Table 1 also shows the thickness of the polyvinyl alcohol-based resin layer in the polarizing laminated film, but in the examples of the present invention, the thickness of the polyvinyl alcohol layer that becomes the polarizer layer (after stretching). It can be seen that a laminated film having a thickness of 10 μm or less is obtained.

Claims (13)

A primer layer forming step of forming a primer layer by applying a primer solution on one side of the base film;
Forming a polyvinyl alcohol-based resin layer on the primer layer, and obtaining a laminated film including the base film, the primer layer, and the polyvinyl alcohol-based resin layer in this order; a polyvinyl alcohol-based resin layer forming step;
A stretching step of stretching the laminated film;
A dyeing step of dyeing the polyvinyl alcohol-based resin layer of the laminated film with a dichroic dye to form a polarizer layer in this order,
A method for producing a polarizing laminated film comprising the base film, the primer layer, and the polarizer layer in this order,
The said primer solution contains the at least 1 sort (s) of crosslinking agent chosen from the group which consists of a dialdehyde type crosslinking agent, an isocyanate type crosslinking agent, and a metal type crosslinking agent, The manufacturing method of a polarizing laminated film characterized by the above-mentioned.   Furthermore, the manufacturing method of the polarizing laminated film of Claim 1 with which the said primer solution contains water-soluble polymer.   The method for producing a polarizing laminated film according to claim 1, wherein the water-soluble polymer is a polyvinyl alcohol-based resin.   The method for producing a polarizing laminated film according to claim 1, wherein the solvent of the primer solution is a solvent containing water.   The manufacturing method of the light-polarizing laminated film in any one of Claims 1-4 whose said crosslinking agent is water solubility or water dispersibility.   The method for producing a polarizing laminated film according to claim 1, wherein the dialdehyde-based crosslinking agent is glyoxal.   The said isocyanate type crosslinking agent is a manufacturing method of the light-polarizing laminated film in any one of Claims 1-5 which is a polyisocyanate which has at least 1 or more isocyanate group in 1 molecule.   The said metal type crosslinking agent is a manufacturing method of the light-polarizing laminated film in any one of Claims 1-5 which is an organometallic compound.   The method for producing a polarizing laminated film according to claim 8, wherein the organometallic compound is a chelate complex.   The manufacturing method of the light-polarizing laminated film in any one of Claims 1-9 whose thickness before the said extending process of the said primer layer is 0.05-1.0 micrometer.   The manufacturing method of the light-polarizing laminated film in any one of Claims 1-10 whose thickness before the said extending process of the said polyvinyl alcohol-type resin layer is 3-30 micrometers.   The manufacturing method of the polarizing laminated film in any one of Claims 1-11 whose thickness of the said polarizer layer 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 of laminating a protective film on a surface opposite to the surface on the base film side of the polarizing laminated film obtained by the method for producing a polarizing laminated film according to claim 1;
A base film peeling step for peeling the base film from the polarizing laminated film;
In this order.

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