JP5885955B2 - Manufacturing method of polarizing plate - Google Patents

Description

  The present invention relates to 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. Conventionally, a polarizing plate made of a polyvinyl alcohol-based resin and a protective film such as triacetyl cellulose are used as the polarizing plate. The polarizer layer (polarizing film) is required to have high optical performance, and in recent years, with the development of liquid crystal display devices such as notebook personal computers and mobile phones, reduction in thickness and weight is required.

  As an example of a method for producing a thin polarizing plate, after applying a solution containing a polyvinyl alcohol-based resin on the surface of a base film to provide a resin layer, the laminate film composed of the base film and the resin layer is stretched, There has been proposed a method of obtaining a polarizing laminated film having a polarizer layer by dyeing, crosslinking (fixing), drying, and forming a polarizer layer from a resin layer (see, for example, Patent Document 1). The method of using this as a polarizing plate as it is, or using the thing which peeled the base film after bonding a protective film to this film as a polarizing plate is disclosed.

  In addition, in the stretching of a laminated film in which a polyvinyl alcohol-based resin layer is provided on the surface of the base film as described above, a method of performing lateral uniaxial stretching has been proposed (see, for example, Patent Documents 2 and 3).

JP 2000-338329 A JP 2003-43257 A JP 2009-300768 A

  In the manufacturing method of the above-mentioned polarizing plate, a minute float and peeling may arise between a base film and a resin layer. This is due to a difference in behavior between the base film and the resin layer when the laminated film composed of the base film and the resin layer is stretched, dyed, crosslinked, and dried. In particular, when stretching more than 5 times in the stretching step, the amount of deformation of each of the base film and the resin layer becomes large, so that the difference in behavior in each step becomes remarkable, and the above-described floating and peeling are likely to occur.

  In order to suppress the occurrence of floating or peeling, it is necessary to increase the adhesion between the base film and the resin layer. For example, there is a method of providing an easy adhesion layer or a primer layer having high adhesion. On the other hand, when the adhesion between the base film and the resin layer is increased, when the base film is peeled off and then used as a polarizing plate, the resin layer is agglomerated and broken due to the peeling of the base film, thereby improving the quality of the polarizing plate. There was an effect. In particular, in a laminated film that has been stretched laterally, if the base film is peeled off in the flow direction of the laminated film, the base film tends to break, and the base film cannot be continuously and cleanly peeled off. It was easy to occur.

  Therefore, the present invention can remove the substrate film cleanly even in the width direction even if the adhesion force between the substrate film and the resin layer is increased to such an extent that it can withstand the steps of stretching, dyeing, and crosslinking. It aims at providing the manufacturing method of the stretched polarizing plate.

  In the laminated film consisting of the base film and the resin layer, the present inventors have found that the adhesion force between the resin layer and the base film is different between the orientation direction of the resin layer and the direction orthogonal thereto. The present invention has been reached.

  The method for producing a polarizing plate of the present invention includes a resin layer forming step of forming a polyvinyl alcohol-based resin layer on at least one surface of a base film to obtain a laminated film, and stretching the laminated film in the width direction. Stretching step for obtaining a film, dyeing step for dyeing the polyvinyl alcohol-based resin layer of the stretched film with a dichroic dye to form a polarizer layer and obtaining a polarizing laminate film, and a polarizer layer for the polarizing laminate film There are a bonding step of bonding a protective film on the surface opposite to the base film of the film to obtain a multilayer film, and a peeling step of continuously peeling the base film from the multilayer film to obtain a polarizing plate. And in the said peeling process, the angle which the peeling direction of a base film and the orientation direction of a polarizer layer make is 20 to 70 degree | times.

  In the peeling step, the angle formed by the multilayer film and the polarizing plate is preferably smaller than the angle formed by the multilayer film and the base film at the peeling point, and the angle formed by the multilayer film and the polarizing plate is 45 degrees or less. Is more preferable.

  According to the present invention, it is possible to produce a polarizing plate by subjecting a laminated film comprising a long base film and a resin layer to treatments such as lateral stretching and dyeing, and then peeling the base film cleanly.

It is a flowchart which shows one Embodiment of the manufacturing method of the polarizing plate of this invention. It is a top view which shows typically the relationship between the peeling direction of a base film, and the orientation direction of a polarizer layer. It is a top view which shows typically the relationship between the peeling direction of a base film, and the orientation direction of a polarizer layer. It is a top view which shows typically the relationship between the angle which a multilayer film and a polarizing plate make, and the angle which a multilayer film and a base film form. It is a top view which shows typically a preferable example regarding the peeling angle of the peeling process in this invention.

  Hereinafter, preferred embodiments of a method for producing a polarizing plate according to the present invention will be described in detail with reference to the drawings.

[Production method of polarizing plate]
FIG. 1 is a flowchart showing an embodiment of a method for producing a polarizing plate of the present invention. According to this, the manufacturing method of a polarizing plate is the resin layer formation process (S10) which forms a polyvinyl alcohol-type resin layer on at least one surface of a elongate base film, and obtains a laminated film, The said laminated film Stretching step (S20) for obtaining a stretched film by stretching, Dyeing step (S30) for obtaining a polarizing laminate film by dyeing the polyvinyl alcohol resin layer of the stretched film with a dichroic dye to form a polarizer layer, A lamination step (S40) for obtaining a multilayer film by laminating a protective film on the surface of the polarizer layer opposite to the substrate film of the polarizer layer, and continuously peeling the substrate film from the multilayer film A peeling step (S50) for obtaining a long polarizing plate 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, for example, on a protective film. This polarizing plate can be used by bonding to another optical film or a liquid crystal cell through an adhesive layer, for example.

<Peeling step (S50)>
In the peeling step (S50), the peeling method of the base film is not particularly limited, but the peeling is performed so that the angle formed by the peeling direction of the base film and the orientation direction of the polarizer layer is 20 degrees or more and 70 degrees or less. After the protective film laminating step (S40), the protective film may be peeled off as it is, or once wound up in a roll shape, a separate peeling step may be provided and peeled off. FIG. 2 is a top view schematically showing the relationship between the peeling direction of the base film and the orientation direction of the polarizer layer in the peeling step (S50). In FIG. 2, the base film 11 is continuously peeled from the long multilayer film 10 unwound from the roll, and the polarizing plate 12 composed of a protective film and a polarizer layer is formed. Here, the orientation direction of the polarizer layer is indicated by an arrow A, the peeling direction of the base film 11 is indicated by an arrow B, the flow direction of the laminated film is indicated by an arrow C, and the peeling direction of the base film (arrow B) The angle formed with the orientation direction of the polarizer layer (arrow A) is denoted by θ. In the present invention, the angle θ formed by the peeling direction of the base film (arrow B) and the orientation direction of the polarizer layer (arrow A) is 20 degrees or more and 70 degrees or less, preferably 30 degrees or more and 60 degrees or less. The base film 11 is continuously peeled.

  By peeling the base film 11 so that the angle θ is 20 degrees or more, the base film 11 is continuously peeled from the laminated film that has been subjected to lateral stretching that is continuously unwound in the flow direction C from the roll. It becomes possible to do. When the angle θ is less than 20 degrees, it is difficult to peel the base film 11 continuously.

  By peeling the base film 11 so that the angle θ is 70 degrees or less, cohesive failure is caused in the polarizer layer from the laminated film that has been subjected to lateral stretching that is continuously unwound in the flow direction C from the roll. It becomes possible to peel the base film 11 continuously and cleanly. Moreover, the base film 11 can be smoothly peeled by peeling so that angle (theta) may be 70 degrees or less.

  The orientation direction of the polarizer layer is a direction in which the main chains of the polyvinyl alcohol-based resin constituting the polarizer layer are aligned by stretching, and is the direction having the highest refractive index in the plane of the polarizer layer. In the polarizer layer, the orientation direction is usually the direction that coincides with the absorption axis. The orientation direction of the polarizer layer coincides with the stretching direction when the stretching in the stretching step (S20) is uniaxial stretching. In the case of biaxial stretching, the orientation direction is often the direction stretched at a higher magnification, which coincides with one of the two stretching directions. In the stretching step (S20) of the present invention, stretching in the width direction is always performed regardless of uniaxial stretching or biaxial stretching, and the orientation direction of the polarizer layer coincides with the width direction.

  FIG. 3 is a top view schematically showing the relationship between the peeling direction of the base film and the orientation direction of the polarizer layer in the peeling step (S50). In FIG. 3, the base film 11 is continuously peeled from the long multilayer film 10 to form a polarizing plate 12 composed of a protective film and a polarizer layer. Here, the orientation direction of the polarizer layer is indicated by an arrow A, the peeling direction of the base film 11 is indicated by an arrow B, the flow direction of the laminated film is indicated by an arrow C, and the peeling direction of the base film (arrow B) The angle formed with the orientation direction of the polarizer layer (arrow A) is denoted by θ. In the present invention, the angle θ formed by the peeling direction of the base film (arrow B) and the orientation direction of the polarizer layer (arrow A) is 20 degrees or more and 70 degrees or less, preferably 30 degrees or more and 60 degrees or less. The base film 11 is continuously peeled. At this time, a roll for transporting and / or winding the peeled substrate film 11 is disposed so as to have an angle of 20 degrees or more and 70 or less with respect to the orientation direction A of the polarizer layer. By peeling the base film 11 through the angle θ, the angle θ formed by the peeling direction of the base film and the orientation direction of the polarizer layer can be adjusted to 20 degrees or more and 70 degrees or less.

  In the peeling step (S50), the angle formed between the multilayer film (the film before peeling the base film) and the polarizing plate at the peeling point is determined between the multilayer film (the film before peeling the base film) and the base film. It is preferable to peel the base film so as to be smaller than the angle formed. FIG. 4 is a top view schematically showing the relationship between the angle between the multilayer film and the polarizing plate and the angle between the multilayer film and the substrate film at the peeling point. In FIG. 4, the base film 11 is peeled from the multilayer film 10 at the peeling point D, and the polarizing plate 12 composed of a protective film and a polarizer layer is formed. Here, at the peeling point D, an angle formed between the multilayer film 10 and the polarizing plate 12 is φp, and an angle formed between the multilayer film 10 and the substrate film 11 is φk. In the present invention, φp <φk is preferable, and φp ≦ 45 degrees is more preferable. Φp is most preferably 0 degrees. By peeling the base film so that φp <φk and further satisfying φp ≦ 45 degrees, cohesive failure generated in the polarizer layer can be suppressed and the base film can be peeled smoothly.

  4 shows a state in which the base film 11 and the polarizing plate 12 are peeled so as to form an angle in the opposite direction with respect to the multilayer film 10 at the peeling point D, but with respect to the multilayer film 10 at the peeling point D. Thus, the base film 11 and the polarizing plate 12 may be peeled so as to form an angle in the same direction. Even in this case, the above-described conditions regarding the angles φp and φk are effective.

  FIG. 5 is a top view schematically showing a preferred example of the peeling angle in the peeling step (S50) in the present invention. As shown in FIG. 5, the angles φp and φk can be adjusted by appropriately selecting the size of the nip rollers, the arrangement position, and the like. In the example shown in FIG. 5, φp = 0 degrees and φp <φk.

Hereinafter, each process other than the peeling process (S50) in FIG. 1 will be described in detail.
<Resin layer forming step (S10)>
In the resin layer forming step (S10), a polyvinyl alcohol-based resin layer is formed on at least one surface of the base film.

(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 is selected according to their glass transition temperature Tg or melting point Tm. You can choose. It is preferable to use a base film that can be stretched in a temperature range suitable for stretching a polyvinyl alcohol-based resin layer laminated thereon.

  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. Moreover, 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.

  The base film is subjected to corona treatment, plasma treatment, flame treatment, etc. on at least the surface on which the polyvinyl alcohol resin layer is formed in order to improve adhesion with the resin layer made of polyvinyl alcohol resin. Also good. Moreover, in order to improve adhesiveness, you may form thin layers, such as a primer layer, in the surface at the side by which the polyvinyl alcohol-type resin layer of a base film is formed. In particular, when stretching is performed at a stretching ratio exceeding 5 times in the stretching step (S20), since the floating and peeling are likely to occur between the base film and the resin layer, the treatment for improving the adhesion as described above, Or it is preferable to provide a primer layer etc.

[Primer layer]
The primer layer is not particularly limited as long as it is a material that exhibits a certain degree of strong adhesion to both the base film and the polyvinyl alcohol-based resin layer. 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.

  The resin constituting the primer layer may be used in a state dissolved in a solvent. Depending on the solubility of the resin, aromatic hydrocarbons such as benzene, toluene and xylene, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and isobutyl acetate, chlorine such as methylene chloride, trichloroethylene and chloroform A general organic solvent such as fluorinated hydrocarbons, alcohols such as ethanol, 1-propanol, 2-propanol, and 1-butanol can also be used. However, if the primer layer is formed using a solution containing an organic solvent, the base material may be dissolved. Therefore, it is preferable to select the solvent in consideration of the solubility of the base material. In consideration of the influence on the environment, the primer layer is preferably formed from a coating solution containing water as a solvent. 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 crosslinking agent to be added to the 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, an epoxy-based, isocyanate-based, dialdehyde-based, or metal-based crosslinking agent can be selected. As the epoxy-based crosslinking agent, either a one-component curable type or a two-component curable type can be used. Examples include epoxies such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, and diglycidyl amine. .

  Examples of isocyanate-based crosslinking agents include tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane triisocyanate, isophorone diisocyanate, and ketoximes thereof. Isocyanates such as block products or phenol block products.

  Examples of the dialdehyde-based crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleidialdehyde, phthaldialdehyde and the like.

  Examples of the metal-based crosslinking agent include metal salts, metal oxides, metal hydroxides, and organometallic compounds, and the type of metal is not particularly limited and may be appropriately selected. 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.

  Preferable examples of the metal organic 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 titanium orthoesters such as tetranormal butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, tetramethyl titanate; titanium acetylacetonate, titanium tetra Titanium chelates such as acetylacetonate, 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. Can be mentioned.

  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 for the titanium organic compound and the zirconium organic compound described above.

  In addition to the above-mentioned low molecular crosslinking agents, polymer crosslinking agents such as methylolated melamine resins and polyamide epoxy resins can also be used. Examples of such commercially available polyamide epoxy resins include “Smiles (registered trademark) Resin 650 (30)” and “Smiles (registered trademark) Resin 675” (all trade names) sold by Sumika Chemtex Co., Ltd. There is.

  When a polyvinyl alcohol-based resin is used as the thermoplastic resin, polyamide epoxy resin, methylolated melamine, dialdehyde, metal chelate crosslinking agent and the like are particularly preferable.

  The ratio of the thermoplastic resin and the cross-linking agent used to form the primer layer ranges from about 0.1 to 100 parts by weight of the cross-linking agent to 100 parts by weight of the resin. Accordingly, it is preferable to select from the range of about 0.1 to 50 parts by weight. The primer layer coating liquid preferably has a solid content concentration of about 1 to 25% by weight.

  The thickness of the primer layer is preferably 0.05 to 1 μm. More preferably, it is 0.1-0.4 micrometer. When the thickness is less than 0.05 μm, the effect of improving the adhesion between the base film and the polyvinyl alcohol layer is small, and when the thickness is more than 1 μm, the polarizing plate becomes thick.

  In forming the primer layer, the coating method to be used is not particularly limited, and roll coating method such as wire bar coating method, reverse coating, gravure coating, die coating method, comma coating method, lip coating method, spin coating method. A screen coating method, a fountain coating method, a dipping method, a spray method, and the like can be appropriately selected from known methods and employed.

(Resin layer)
As the polyvinyl alcohol resin used for the 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 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 forming the polarizer layer are remarkably inferior.

  The degree of saponification referred to here is the unit ratio (mol%) of the ratio of the acetate group contained in the polyvinyl acetate resin, which is the raw material of the polyvinyl alcohol resin, to the hydroxyl group by the saponification step. A numeric value defined by an expression. It can be determined by the method defined in JIS K 6726 (1994).

Degree of saponification (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.

  The polyvinyl alcohol-based resin may be modified polyvinyl alcohol partially modified. Examples thereof include those obtained by modifying polyvinyl alcohol resins 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. 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 mol%) manufactured by Kuraray Co., Ltd. ), PVA624 (degree of saponification: 95.0 to 96.0 mol%) and PVA617 (degree of saponification: 94.5 to 95.5 mol%); for example, AH-26 (degree of saponification) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. : 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), JM-33 (degree of saponification: 93) of Nippon Vinegar Poval Co., Ltd. .5-95.5 mol%), JM 26 (degree of saponification: 95.5-97.5 mol%), JP-45 (degree of saponification: 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 use suitably in formation of an alcohol-type resin film.

  In the above-mentioned polyvinyl alcohol resin, additives such as a plasticizer and a surfactant may be added as necessary. As the plasticizer, polyols and condensates thereof can be used, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The blending amount of the additive is not particularly limited, but is preferably 20% by weight or less in the polyvinyl alcohol resin.

  The thickness of the resin layer is preferably more than 3 μm and 60 μm or less. If it exceeds 60 μm, the thickness of the finally obtained polarizer layer may exceed 10 μm, which is not preferable.

  The resin layer in the present invention is preferably formed by coating a polyvinyl alcohol resin solution obtained by dissolving polyvinyl alcohol resin powder in a good solvent on one surface of the substrate film and evaporating the solvent. It is formed. By forming the resin layer in this way, it can be formed thin. As a method of applying a polyvinyl alcohol resin solution to 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 coating method. A method, a fountain coating method, a dipping method, a spray method and the like can be appropriately selected from known methods. 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.

  In addition, the resin layer in this invention can also be formed by sticking the raw film which consists of polyvinyl alcohol-type resins on one surface of a base film.

<Extension process (S20)>
Here, a laminated film composed of a base film and a polyvinyl alcohol-based resin layer is stretched in the width direction to obtain a stretched film. 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 resin layer made of the polyvinyl alcohol-based resin is not sufficiently oriented, and as a result, the degree of polarization of the polarizer layer may not be sufficiently high. On the other hand, if the draw ratio exceeds 17 times, the laminated film is likely to break during stretching, and at the same time, the thickness of the stretched film becomes unnecessarily thin, and the workability and handling properties in the subsequent process may be reduced. In the stretching treatment, it is possible to apply an overfeed of preferably 10% to 70% in order to stretch in the width direction and shrink the flow direction to improve uniaxiality. The stretching process in the stretching step (S20) is not limited to one-stage stretching, and can be performed in multiple stages. When performing in multiple stages, the stretching process is carried out so that the stretching ratio of all stages of the stretching process is preferably more than 5 times.

  Examples of the stretching method in the width direction in the stretching step (S20) include a tenter method and a pin 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 process (S30)>
Here, the 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 it is usually preferably in the range of 15 seconds to 15 minutes, and more preferably 30 seconds 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 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 10-90 degreeC.

  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, ventilation 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. Through the above dyeing step (S30), the resin layer has a function as a polarizer. In this specification, the 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.

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

  The thickness of the polarizer layer (the thickness of the stretched polyvinyl alcohol resin film) is preferably 15 μm or less, more preferably 10 μm or less, and even more 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.

<Pasting step (S40)>
Here, a protective film is bonded to the surface opposite to the base film of the polarizer layer of the polarizing laminated film to obtain a multilayer film. As a method of bonding a protective film, the method of bonding a polarizer layer and a protective film with an adhesive layer, and the method of bonding a polarizer layer surface and a protective film with an adhesive layer are mentioned. After the bonding step (S40), the polarizing plate is formed through the above-described peeling step (S50).

(Protective film)
The protective film may be a simple protective film having no optical function, or may be a protective film having an optical function such as a retardation film or 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.

  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 enhance the adhesiveness with the polarizer layer. 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.

(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 polarizer layer or the protective film is not particularly limited, and a solution containing each component including the above-mentioned base polymer is applied on the polarizer layer or the protective film. After drying to form a pressure-sensitive adhesive layer, it may be bonded to a separator or other types of film, or after forming a pressure-sensitive adhesive layer on the separator, it is laminated on the surface of the polarizer layer or the protective film. May be. In addition, when forming the pressure-sensitive adhesive layer on the polarizer layer or the protective film, if necessary, the surface of the polarizer layer or the protective film, or one or both of the pressure-sensitive adhesive layers is subjected to an adhesion treatment, for example, a corona treatment. Also 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. The polyvinyl alcohol resin used as an adhesive includes a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and other monomers copolymerizable with vinyl acetate. And vinyl alcohol copolymers obtained by saponifying the copolymer, and modified polyvinyl alcohol polymers obtained by partially modifying these 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 uniformly applied or poured onto the surface of the polarizer layer or the protective film, and the other film is stacked on the coated surface. The method of bonding by a roll etc. and drying is mentioned. 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 polarizer layer or the protective film, the polarizing laminate film and the protective film are sandwiched by a nip roll or the like and bonded together by bonding the films. 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 the adhesiveness, a surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment, or the like may be appropriately performed on the adhesion surface of the polarizer layer and the protective film. Examples of the saponification treatment include a method of immersing in an alkaline aqueous 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 on a polarizer layer or a protective film by irradiation with active energy rays, the various functions of the polarizing plate after passing through all steps, such as transmittance, hue, and transparency of these films, do not deteriorate. It is preferable to perform curing under conditions.

(Double-sided resin layer laminated film)
In the production method of the present invention, the formation of the resin layer in the resin layer forming step (S10) is not only formed on one surface of the base film, but also formed on both surfaces of the base film. This is also included. When the resin layers are formed on both surfaces, two polarizing plates are formed through the steps S10 to S50. In this case, a multilayer film composed of the first protective film / first polarizer layer / base film / second polarizer layer / second protective film is obtained through the bonding step (S40).

  When the resin layers are formed on both surfaces of the base film, the peeling step (S50) of peeling the base film from the multilayer film to obtain a polarizing plate is the same as the first polarizer layer and the base film. A laminate composed of a base film / second polarizer layer / second protective film which is separated from the first peeling step for separation from the material film by peeling, and a base film and a second polarizer layer And a second peeling step of separating by peeling. A first polarizing plate is formed by the first peeling step, and a second polarizing plate is formed by the second peeling step.

  The angle θ between the peeling direction of the base film (arrow B) and the orientation direction of the polarizer layer (arrow A) is the peeling direction of the base film (that is, base film / second) in the first peeling step. It means the angle formed between the polarizer layer / the second protective film laminate direction) and the orientation direction of the first polarizer layer. In the second peeling step, the base film peeling direction and the second It means the angle made with the orientation direction of the polarizer layer. The condition of the angle θ is as described above.

  Further, the angle φp formed between the multilayer film and the polarizing plate at the peeling point is the multilayer film (that is, the first protective film / first polarizer layer / base film / second polarizer layer / It means the angle formed between the laminate comprising the second protective film and the first polarizing plate (that is, the laminate comprising the first polarizer layer / the first protective film). In the second peeling step, the multilayer film (ie Means the angle formed by the base film / second polarizer layer / second protective film laminate) and the second polarizing plate (that is, second polarizer layer / second protective film laminate). . Further, the angle φk formed between the multilayer film and the base film at the peeling point is the multilayer film (that is, the first protective film / first polarizer layer / base film / second polarizer layer) in the first peeling step. / Laminated body made of the second protective film) and an angle formed by the base film (that is, the laminated body made of the base film / second polarizer layer / second protective film). It means an angle formed by a film (that is, a laminate comprising a base film / second polarizer layer / second protective film) and the base film. The conditions for the angles φp and φk are as described above.

(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.).

[Production of Polarizing Plates of Examples 1 to 5 and Comparative Examples 1 to 4]
<Preparation of base film>
Homopolypropylene which is a propylene homopolymer on both sides of a resin layer made of a random copolymer of propylene / ethylene containing 5% by weight of ethylene units (“Sumitomo Nobrene W151” manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 138 ° C.) A long base film having a three-layer structure in which a resin layer composed of “Sumitomo Nobrene FLX80E4” manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 163 ° C. is disposed by coextrusion molding using a multilayer extrusion molding machine. Produced. The total thickness of the obtained base film was 150 μm, and the thickness ratio (FLX80E4 / W151 / FLX80E4) of each layer was 3/4/3.

<Formation of primer layer>
Polyvinyl alcohol powder (“Z-200” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization 1100, average degree of saponification 99.5 mol%) was dissolved in 95 ° C. hot water to give a concentration of 3% by weight of polyvinyl alcohol. An aqueous solution was prepared. The resulting aqueous solution was mixed with 5 parts by weight of a crosslinking agent (“SUMIREZ RESIN 650” manufactured by Sumitomo Chemical Co., Ltd.) with respect to 6 parts by weight of polyvinyl alcohol powder. The obtained mixed aqueous solution was continuously applied on the corona-treated surface of the base film subjected to the corona treatment using a gravure coater, and dried at 80 ° C. for 10 minutes, whereby a primer layer having a thickness of 0.2 μm. Formed.

<Resin layer forming step (S10)>
Polyvinyl alcohol powder (“PVA124” manufactured by Kuraray Co., Ltd., average polymerization degree 2400, average saponification degree 98.0-99.0 mol%) was dissolved in hot water at 95 ° C., and a polyvinyl alcohol aqueous solution having a concentration of 8% by weight was dissolved. Prepared. The obtained aqueous solution is coated on the primer layer using a comma coater and dried at 80 ° C. for 5 minutes, whereby a laminated film having a three-layer structure consisting of a base film / primer layer / polyvinyl alcohol resin layer is formed. Was made. The thickness of the polyvinyl alcohol-based resin layer was 28.2 μm. The obtained laminated film was wound up on a roll.

<Extension process (S20)>
The laminated film unwound from the roll was uniaxially stretched at a fixed end 5.5 times in the width direction over 4 minutes at a stretching temperature of 160 ° C. with a tenter stretching apparatus to obtain a stretched film. The obtained stretched film had a thickness of 28.5 μm, and the polyvinyl alcohol-based resin layer had a thickness of 5.1 μm. The obtained stretched film was wound up on a roll.

<Dyeing process (S30)>
A polarizing laminated film was produced from the stretched film by the following procedure. First, the stretched film unwound from the roll is immersed in a dyeing solution at 30 ° C., which is an aqueous solution containing 30 ° C. iodine and potassium iodide, for about 150 seconds to dye the polyvinyl alcohol resin layer, and then at 10 ° C. The excess iodine solution was washed away with pure water. Next, it was immersed for 600 seconds in the 76 degreeC bridge | crosslinking solution which is the aqueous solution containing a boric acid and potassium iodide. Thereafter, the film was washed with pure water at 10 ° C. for 4 seconds, and finally dried at 80 ° C. for 300 seconds to form a polarizer layer, thereby obtaining a polarizing laminated film. The obtained polarizing laminated film was wound up on a roll.

<Pasting step (S40)>
A protective film was bonded to the polarizing laminate film by the following procedure. First, polyvinyl alcohol powder (“KL-318” manufactured by Kuraray Co., Ltd., average polymerization degree 1800) was dissolved in hot water at 95 ° C. to prepare a polyvinyl alcohol aqueous solution having a concentration of 3% by weight. The resulting aqueous solution was mixed with 1 part by weight of a crosslinking agent (“SUMIREZ RESIN 650” manufactured by Sumitomo Chemical Co., Ltd.) with respect to 2 parts by weight of polyvinyl alcohol powder to obtain an adhesive solution.

  Next, after applying the adhesive solution on the polarizer layer of the polarizing laminated film unwound from the roll, a protective film made of triacetyl cellulose (TAC) ("KC4UY" manufactured by Konica Minolta Opto Co., Ltd.) Bonding was performed to obtain a multilayer film consisting of five layers of protective film / adhesive layer / polarizer layer / primer layer / base film. The obtained multilayer film was wound up on a roll.

<Peeling step (S50)>
The base film was peeled from the obtained multilayer film to prepare a polarizing plate comprising 4 layers of protective film / adhesive layer / polarizer layer / primer layer. At this time, the angle θ formed by the peeling direction of the base film (arrow B) and the orientation direction of the polarizer layer (arrow A), the angle φp formed by the multilayer film and the polarizing plate, and the multilayer film and the base film The angle was measured with respect to φk as shown in Table 1 below. When the angle φp and the angle φk were not 0 degrees at the peeling point, the base film and the polarizing plate were peeled so as to have an angle on the opposite side with respect to the multilayer film.

[Evaluation of polarizing plates of Examples 1 to 5 and Comparative Examples 1 to 4]
About each polarizing plate produced as mentioned above, "state of a peeling surface" and "peeling stability" were evaluated. The evaluation results are shown in Table 1 below. The “peeling stability” is an evaluation as to whether or not the base film could be peeled stably. Even if the cohesive failure does not occur, intermittent peeling called zippering may occur and stability at the time of peeling may not be obtained. When zippering occurs, the peeling force at the time of peeling may repeatedly increase and decrease, or the part where peeling occurs may fluctuate back and forth, resulting in a problem that the peeling angle is not stable.

  10 multilayer film, 11 substrate film, 12 polarizing plate.

Claims (3)

A resin layer forming step of forming a polyvinyl alcohol-based resin layer on one surface of the long base film to obtain a laminated film; and
A stretching step of stretching the laminated film in the width direction to obtain a stretched film;
Dyeing the polyvinyl alcohol-based resin layer of the stretched film with a dichroic dye to form a polarizer layer and obtaining a polarizing laminated film; and
A laminating step of obtaining a multilayer film by laminating a protective film on the surface opposite to the base film of the polarizer layer of the polarizing laminated film,
A peeling step of continuously peeling the base film from the multilayer film to obtain a long polarizing plate,
The manufacturing method of a polarizing plate whose angle which the peeling direction of the said base film and the orientation direction of the said polarizer layer make in the said peeling process is 20 to 70 degree | times.   2. The method for producing a polarizing plate according to claim 1, wherein, in the peeling step, an angle formed by the multilayer film and the polarizing plate is smaller than an angle formed by the multilayer film and the base film at a peeling point.   The manufacturing method of the polarizing plate of Claim 2 whose angle which the said multilayer film and the said polarizing plate make at the said peeling point in the said peeling process is 45 degrees or less.

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