JP5602823B2 - Polarizing laminated film and method for producing polarizing plate, polarizing laminated film - Google Patents

Description

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

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

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

  Furthermore, in Patent Document 2, a polyvinyl alcohol-based resin layer is provided on both surfaces of a base film, and then the polyvinyl alcohol-based resin layer is stretched together with the base film, followed by a dyeing / crosslinking step. A method of obtaining two polarizer layers at the same time by using as a polarizer layer is disclosed.

JP 2000-338329 A JP 2012-159778 A

  In a liquid crystal display device, two polarizing plates are used with one disposed on the viewing side of the liquid crystal cell and the other disposed on the backlight side of the liquid crystal cell. For example, in small and medium-sized liquid crystal display devices, the polarizing plate on the backlight side is often used as a transflective type by pasting a brightness enhancement film, etc. In this case, the polarizing performance of the polarizing plate on the backlight side Even if it is not high, the contrast of the display device is not substantially lowered. For this reason, the polarizing plate on the backlight side may be designed to increase the transmittance as a liquid crystal display device by designing the transmittance to be bright even if the degree of polarization is slightly low.

  According to the method described in Patent Document 2, there is an advantage that two polarizer layers can be obtained simultaneously. When the polarizer layer having a high transmittance and the polarizer layer having a low transmittance are obtained at the same time, the present inventor efficiently provides a polarizing plate set useful for constructing a liquid crystal display device having a high transmittance. I found out that I can do it. That is, the present invention relates to polarized light in which two polarizer layers having different transmittances, more specifically, a difference in average value of visibility-adjusted single transmittances displayed in units of%, exceeding 0.3 points can be obtained simultaneously. It aims at providing the manufacturing method of a conductive laminated film, and the manufacturing method of a polarizing plate. Another object of the present invention is to provide a polarizing laminate film having two polarizer layers, one having high transmittance and the other having low transmittance.

The present invention includes the following.
[1] A method for producing a polarizing laminate film comprising a base film and two polarizer layers respectively formed on both surfaces of the base film,
A resin layer forming step of forming a first polyvinyl alcohol-based resin layer on one surface of the base film and forming a second polyvinyl alcohol-based resin layer on the other surface to obtain a laminated film;
A stretching step of stretching the laminated film;
The first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer of the laminated film after stretching are brought into contact with a dye solution containing a dichroic dye and dyed with the dichroic dye to thereby form two polarized lights. A dyeing step for forming a child layer,
In the dyeing step, when the time when the first polyvinyl alcohol resin layer is in contact with the dye solution is T1, and the time when the second polyvinyl alcohol resin layer is in contact with the dye solution is T2, the following formula:
Ratio of contact time difference (%) = (T1-T2) / {(T1 + T2) / 2} × 100
The manufacturing method of a light-polarizing laminated film in which the ratio of the contact time difference calculated from is over 4% in absolute value.

[2] The ratio of the contact time between difference is an absolute value of 4.5% or more, the production method of the polarizing laminate film according to [1].

[3] The dyeing step transports the laminated film in the dyeing solution while bringing the first polyvinyl alcohol resin layer and / or the second polyvinyl alcohol resin layer into contact with a guide roll,
Adjusting the time when the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer are in contact with the guide roll, the time T1 when the first polyvinyl alcohol-based resin layer is in contact with the dyeing solution, The polarizing laminate according to [1] or [2], wherein a time T2 at which the second polyvinyl alcohol-based resin layer contacts the dyeing solution is adjusted so that a ratio of the contact time difference falls within a desired numerical range. A method for producing a film.

  [4] Production of the polarizing laminated film according to any one of [1] to [3], which includes a bonding step of bonding a protective film to the surface of at least one of the polarizer layers after the dyeing step. Method.

  [5] The method for producing a polarizing laminated film according to [4], wherein a protective film is bonded to the surfaces of the two polarizer layers in the bonding step.

[6] A method for producing a polarizing plate comprising a polarizer layer and a protective film,
Using the polarizing laminated film obtained by the production method according to the above [4] or [5], the laminate of the polarizer layer and the protective film in the polarizing laminated film is peeled from the base film. The manufacturing method of a polarizing plate which has the peeling process which obtains a polarizing plate.

[7] A base film and two polarizer layers formed on both surfaces of the base film from a polyvinyl alcohol-based resin and adsorbing and orienting the dichroic dye by uniaxial stretching and dyeing with a dichroic dye With
The two polarizer layers are polarizing laminated films in which a difference in average value of visibility-adjusted single transmittances expressed in% unit exceeds 0.3 points.

  [8] The polarizing laminated film according to [7], wherein the difference between the average values of the visibility-corrected single transmittances displayed in% units is 0.45 points or more between the two polarizer layers.

[9] In the liquid crystal display device, a polarizing plate set comprising two polarizing plates used by being arranged on both sides of the liquid crystal cell,
The two polarizing plates are polarizing plate sets each including one of the two polarizer layers of the polarizing laminated film according to [7].

  According to the polarizing laminated film manufactured by the method of the present invention, two polarizer layers having different transmittances can be obtained simultaneously, and two polarizing plates having different transmittances can be obtained simultaneously.

It is a flowchart which shows the outline | summary of the manufacturing method of the polarizing plate of this invention. It is a flowchart which shows typically an example of the manufacturing method of the polarizing plate of this invention. It is sectional drawing which shows typically an example of the processing method of the stretched film of this invention. It is sectional drawing which shows typically the dyeing | staining tank of 1st Embodiment.

  The present invention relates to a polarizing laminate film, a method for producing a polarizing plate, a polarizing laminate film, and a polarizing plate set. In this specification, the laminated body provided with the polyvinyl alcohol-type resin layer (layer which consists of polyvinyl alcohol-type resin) on the surface of a base film is called "laminated film." For the “laminated film”, a laminate having a polyvinyl alcohol resin layer on one surface of the base film is referred to as a “single area layer film”, and a laminate having a polyvinyl alcohol resin layer on both surfaces of the base film. The body is sometimes referred to as “double-sided laminated film”.

  Moreover, the polyvinyl alcohol-type resin layer which has a function as a polarizer is called "polarizer layer", and the laminated body of a base film and a polarizer layer is called "polarizing laminated film." For “polarizing laminate film”, a laminate having a polarizer layer on one side of a base film is referred to as a “single-sided polarizing laminate film”, and a laminate having a polarizer layer on both sides of the base film. In some cases, the body is used as a “double-sided 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 of the polarizing laminated film, the polarizing plate and the polarizing plate set will be described in detail.

[Base film]
As the resin constituting the base film, for example, thermoplastic resins excellent in transparency, mechanical strength, thermal stability, stretchability and the like are preferably used, and their glass transition temperature (Tg) or melting point (Tm). Depending on the case, an appropriate resin can be selected. 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 single layer using only one kind of the above-mentioned resin, or may be a blend of two or more kinds of resins. Of course, a multilayer film may be formed instead of a single layer.

  The polyolefin-based resin is a polymer having a chain olefin such as ethylene or propylene as a main monomer. Further, a propylene-ethylene copolymer obtained by copolymerizing propylene with ethylene can also be used. Copolymerization can also be performed with other types of monomers, and examples of other types of monomers copolymerizable with propylene include, in addition to ethylene, α-olefins. The α-olefin copolymerized with propylene has 4 or more carbon atoms, and is 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 methyl-1-butene, 3-methyl-1-pentene and 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 measurement. The polyolefin-based resin is preferably used as a base film in the present invention because it is easily stretched stably at a high magnification.

  Among polyolefin resins, propylene resins are preferred, and examples thereof include propylene homopolymer, propylene-ethylene random copolymer, propylene-1-butene random copolymer, and propylene-ethylene-1-butene random copolymer. Etc.

  The stereoregularity of the propylene-based resin is preferably substantially isotactic or syndiotactic. A 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-based resin is a polymer having an ester bond, and specifically, is often composed of a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. The polyvalent carboxylic acid used is mainly a divalent dicarboxylic acid or an ester thereof, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. The polyhydric alcohol used is also mainly a divalent diol, and examples thereof include propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

  A typical example of the polyester resin is polyethylene terephthalate which is a polycondensate of terephthalic acid and ethylene glycol. Polyethylene terephthalate is a crystalline resin, but the one in a state before crystallization treatment is more easily subjected to treatment such as stretching. If necessary, it can be crystallized during stretching or by heat treatment after stretching. Further, a copolymerized polyester having a crystallinity lowered (or made amorphous) by further copolymerizing another monomer with a polyethylene terephthalate skeleton is also preferably used. Examples of such resins include those obtained by copolymerizing cyclohexanedimethanol and isophthalic acid. Since these resins are also excellent in stretchability, they can be suitably used.

  Specific polyester resins other than polyethylene terephthalate and copolymers thereof include polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane. Examples thereof include dimethyl naphthalate. These blend resins and copolymers can also be used.

  The cyclic polyolefin-based resin is a general term for polymers having a cyclic olefin as a main constituent monomer, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. The resin currently used is mentioned. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and α-olefins such as ethylene or propylene (typically random copolymers). There are graft polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers. As the cyclic polyolefin resin, a norbornene resin is particularly preferably used.

  Various products are commercially available as cyclic polyolefin resins. Specific examples include TOPAS (manufactured by Topas Advanced Polymers), Arton (manufactured by JSR Corporation), ZEONOR (manufactured by Nippon Zeon Co., Ltd.), ZEONEX (manufactured by Nippon Zeon Corporation), Appel (made by Mitsui Chemicals).

  The (meth) acrylic resin is a polymer having a compound having a (meth) acryloyl group as a main constituent monomer. 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, methyl (meth) acrylate-styrene copolymer (such as what is called MS resin), copolymer of methyl methacrylate and a compound having an alicyclic hydrocarbon group (for example, Methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, a polymer having a C1-6 alkyl ester of (meth) acrylic acid as a main component, such as poly (meth) acrylate methyl, can be used. More preferable examples of the (meth) acrylic resin include a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  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 in which a part of the hydroxyl group is modified with another substituent are also included. Among these, cellulose triacetate is particularly preferable. Many products of the cellulose triacetate film are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available cellulose triacetate films are Fujitac TD80 (Fuji Film Co., Ltd.), Fujitac TD80UF (Fuji Film Co., Ltd.), Fujitac TD80UZ (Fuji Film Co., Ltd.), Fujitac TD40UZ (Fuji Film). KC8UX2M (manufactured by Konica Minolta Opto), KC4UY (manufactured by Konica Minolta Opto), and the like.

  The polycarbonate resin is a polymer having a carbonate bond (—O—CO—O—) in the main chain. It is a kind of engineering plastic and is a resin having high impact resistance, heat resistance and flame retardancy. Moreover, since it has high transparency, it is used suitably also for an optical use. For 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 dependence, and the like are commercially available and can be suitably used. Such polycarbonate resins are widely available on the market. For example, Panlite (manufactured by Teijin Chemicals Ltd.), Iupilon (manufactured by Mitsubishi Engineering Plastics), SD Polyca (manufactured by Sumitomo Dow), Caliber (Dow) Chemical).

  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 proportion 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 ratio 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.

  The thickness of the base film can be determined as appropriate, but 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, especially 5 to 200 μm. Is more preferable. Furthermore, a base film having a thickness in the range of 5 to 150 μm is most preferable.

  The base film may be subjected to corona treatment, plasma treatment, flame treatment, or the like on at least the surface on which the resin layer is formed in order to improve adhesion with the resin layer. In order to improve adhesion, a thin layer such as a primer layer or an adhesive layer may be formed on the surface of the base film on the side where the resin layer is formed. In addition, when an adhesive bond layer, a corona treatment layer, etc. are provided, a base film means the thing of the state which does not contain them.

[Primer layer]
A primer layer may be formed on the surface of the base film. The primer layer may be formed of 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 forming 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 be used. However, when the primer layer is formed from a solution containing an organic solvent, the base film may be dissolved. Therefore, it is preferable to select an appropriate solvent in consideration of the solubility of the base film. In consideration of the influence on the environment, the primer layer is preferably formed from a coating solution containing water as a solvent. Of these, polyvinyl alcohol resins having excellent adhesion are preferably used.

  Specifically, the polyvinyl alcohol-based resin used for the primer layer is polyvinyl alcohol and its derivatives. Polyvinyl alcohol derivatives include polyvinyl formal, polyvinyl acetal, etc., as well as polyvinyl alcohol, 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 resins, it is preferable to use polyvinyl alcohol.

  In order to increase the strength of the primer layer, a crosslinking agent may be added to the thermoplastic resin. As the cross-linking agent to be added to the thermoplastic resin, known ones such as organic and inorganic can be used. What is necessary is just to select a more suitable thing suitably with respect to the thermoplastic resin to be used. For example, what is necessary is just to select suitably from an epoxy type crosslinking agent, an isocyanate type crosslinking agent, a dialdehyde type crosslinking agent, a metal type crosslinking agent, etc.

As the epoxy-based crosslinking agent, either a one-component curable type or a two-component curable type can be used. Examples include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di- or tri-glycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diglycidyl amine and the like. Examples of the isocyanate-based crosslinking agent that can be used include tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis (4-phenylmethane) triisocyanate, isophorone diisocyanate, and these. Ketoxime block product or phenol block product.

Examples of the dialdehyde-based crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleidialdehyde, and phthaldialdehyde. Examples of the metal-based crosslinking agent include metal salts and metals. An oxide, a metal hydroxide, an organometallic compound, etc. are mentioned, The kind of metal is not specifically limited here, What is necessary is just to select suitably.

  As metal salts, metal oxides and metal hydroxides, for example, magnesium, calcium, aluminum, iron, nickel, zirconium, titanium, silicon, boron, zinc, copper, vanadium, chromium, tin, or more divalent atoms And metal salts having a valence, oxides thereof and hydroxides thereof.

  An organometallic compound is a compound having in its 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. Here, the organic group means a monovalent or polyvalent group containing at least a carbon element, and can be, for example, an alkyl group, an alkoxy group, an acyl group, or the like. Further, the bond does not mean only a covalent bond, but may be a coordinate bond by coordination of a chelate compound or the like.

  As a suitable example of the metal organic compound used as a crosslinking agent, an organic titanium compound, an organic zirconium compound, an organic aluminum compound, and an organic silicon compound are mentioned. These organometallic compounds may be used alone or in a suitable mixture of two or more.

  Specific examples of the organic titanium compound include: tetranormal butyl titanate, tetraisopropyl titanate, butyl titanate dimer, titanium orthoesters such as tetra (2-ethylhexyl) titanate, tetramethyl titanate; titanium acetylacetonate, titanium tetraacetylacetate There are titanium chelates such as narate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate, titanium triethanolamate, and titanium ethyl acetoacetate; and titanium acylates such as polyhydroxytitanium stearate.

  Specific examples of the organic zirconium compound include zirconium normal propionate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, and zirconium acetylacetonate bisethylacetoacetate. .

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

  Specific examples of the organosilicon compound include compounds in which the ligands exemplified above for the organotitanium compound and the organozirconium compound are bonded to silicon.

  In addition to the low-molecular crosslinking agents described so far, polymeric crosslinking agents such as methylolated melamine resins and polyamide epoxy resins can also be used. Examples of commercially available polyamide epoxy resins include “Smilease Resin 650 (30)” and “Smilease Resin 675” (both trade names) sold by Taoka Chemical Co., Ltd.

  When a polyvinyl alcohol-based resin is used as the thermoplastic resin for forming the primer layer, polyamide epoxy resin, methylolated melamine, dialdehyde, metal chelate crosslinking agent and the like are preferably used as the crosslinking agent.

  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 with respect 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 primer layer preferably has a thickness in the range of about 0.05 to 1 μm. More preferably, it is 0.1-0.4 micrometer. If the primer layer is too thin, the adhesion between the base film and the polyvinyl alcohol resin layer is reduced. On the other hand, if the primer layer is too thick, the polarizing plate itself becomes thick, which is not preferable.

  In forming the primer layer, the coating method to be used is not particularly limited, and a wire bar coating method, a roll coating method such as reverse coating or gravure coating, a die coating method, a comma coating method, a lip coating method, or a spin coating method. And a known method such as a screen coating method, a fountain coating method, a dipping method, or a spray method.

[Polarizer]
Specifically, the polarizer layer is obtained by dyeing a uniaxially stretched polyvinyl alcohol resin layer with a dichroic dye and adsorbing and orienting the dichroic dye. As the polyvinyl alcohol resin, 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.

  A film obtained by forming such a polyvinyl alcohol-based resin constitutes the polarizer layer according to the present invention. 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.

  The polarizer layer needs to be stretched and oriented, and is preferably stretched at a stretch ratio of more than 5 times, more preferably more than 5 times and not more than 17 times.

  In the polarizer layer, the dichroic dye is adsorbed and oriented on the stretched and oriented polyvinyl alcohol resin as described above. The thickness of the polarizer 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.

  The polyvinyl alcohol resin used for the polarizer layer preferably has a saponification degree of 80 mol% or more, more preferably 90 mol% or more, and particularly 94 mol% or more. If the degree of saponification is too low, the water resistance and heat-and-moisture resistance after making the polarizing plate may not be sufficient. Also, it may be a completely saponified product (having a saponification degree of 100 mol%), but if the saponification degree is too high, the dyeing speed becomes slow, and the production time is required to give sufficient polarization performance. In some cases, the polarizer may become long or a polarizer having sufficient polarization performance may not be obtained. Therefore, the saponification degree is preferably 99.5 mol% or less, more preferably 99 mol% or less, or 99.0 mol% or less.

The degree of saponification referred to here is the unit ratio (moles) of the ratio of acetate groups (acetoxy groups: —OCOCH ₃ ) contained in polyvinyl acetate resin, which is a raw material for polyvinyl alcohol resins, to hydroxyl groups by saponification treatment. %) And is defined by the following formula;
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, and hence the lower the proportion of acetate groups that inhibit crystallization. The saponification degree can be determined by a method defined in JIS K 6726-1994 “Testing method for polyvinyl alcohol”.

  Further, the polyvinyl alcohol resin used in the present invention may be a modified polyvinyl alcohol partially modified. For example, polyvinyl alcohol resin modified with olefins such as ethylene or propylene, modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid or crotonic acid, modified with alkyl ester of unsaturated carboxylic acid And those modified with acrylamide. 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 usually in the range of about 100 to 10000, preferably 1500 to 8000, and more preferably 2000 to 5000. The average degree of polymerization here can also be determined by a method defined in JIS K 6726-1994 “Testing method for polyvinyl alcohol”.

  Examples of the polyvinyl alcohol-based 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 to 96.0 mol%) and PVA617 (degree of saponification: 94.5 to 95.5 mol%); for example, AH manufactured by Nippon Synthetic Chemical Industry Co., Ltd. -26 (degree of saponification: 97.0 to 98.8 mol%), AH-22 (degree of saponification: 97.5 to 98.5 mol%), NH-18 (degree of saponification: 98.0 to 99) 0.0 mol%) and N-300 (degree of saponification: 98.0 to 99.0 mol%); for example, JC-33 (degree of saponification: 99.0 mol%) manufactured by Nihon Vinegar Poval Co., Ltd. JM-33 (degree of saponification: 93.5-95.5 mol%), M-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) 9F mol%), JF-17L (degree of saponification: 98.0-99.0 mol%) and JF-20 (degree of saponification: 98.0-99.0 mol%), etc. In the invention, these can be suitably used.

  Specific examples of the dichroic dye used for dyeing the polyvinyl alcohol-based resin layer include iodine and dichroic organic dyes. Examples of dichroic 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 There are Sky Blue, Direct First Orange S and First Black. These dyes are commercially available. Only one type of dichroic dye may be used, or two or more types 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 an optical function such as a retardation film or a brightness enhancement film. The material constituting the protective film is not particularly limited. For example, a cyclic polyolefin resin, a cellulose acetate resin such as triacetyl cellulose or diacetyl cellulose, a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate, or a polycarbonate resin. Materials that have been widely used in the art such as resins, acrylic resins, and polypropylene resins can be used.

  Examples of the cyclic polyolefin-based resin include commercially available products such as TOPAS (manufactured by Topas Advanced Polymers), Arton (manufactured by JSR Corporation), ZEONOR (manufactured by ZEON Corporation), ZEONEX (ZEONEX) ( Nippon Zeon Co., Ltd.), Apel (Mitsui Chemicals Co., Ltd.), etc. can be used suitably. 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, commercially available products of cyclic polyolefin resin films that have been formed in advance, such as Essina (manufactured by Sekisui Chemical Co., Ltd.), ZEONOR film (manufactured by Nippon Zeon Co., Ltd.), and in some cases further provided with a phase difference, are used. May be.

  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 orthogonal 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, and saponification treatment is performed on the surface to be bonded to the polarizer layer. Is preferred. 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 TD80 (Fuji Film Co., Ltd.), Fujitac TD80UF (Fuji Film Co., Ltd.), Fujitac TD80UZ (Fuji Film Co., Ltd.), Fujitac TD40UZ. (Manufactured by FUJIFILM Corporation), KC8UX2M (manufactured by Konica Minolta Opto Corporation), KC4UY (manufactured by Konica Minolta Opto Corporation), and the like can be suitably used.

  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, the stretched cellulose acetate type-resin film can also be used. The cellulose acetate-based resin film is usually subjected to a saponification treatment in order to improve the adhesion with the polarizer layer. The saponification treatment is performed by immersing the film in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.

  An optical layer 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 viewpoint of thinning, and is preferably 90 μm or less, and more preferably 50 μm or less. On the other hand, if the thickness is too thin, the strength may be lowered and the workability may be hindered. Therefore, the thickness is preferably 5 μm or more.

<Production method of polarizing plate>
FIG. 1 is a flowchart showing an outline of a method for producing a polarizing plate of the present invention, and FIG. 2 is a flowchart schematically showing an example of a method for producing a polarizing plate of the present invention. Among these, the manufacturing method of the light-polarizing laminated film of the present invention includes a resin layer forming step (S10) in which a polyvinyl alcohol-based resin layer is formed on both surfaces of the base film to obtain a double-sided laminated film, Stretching step (S20) for stretching, and Dyeing step (S30) for staining the polyvinyl alcohol-based resin layer on both sides of the stretched double-sided laminated film with a dichroic dye by bringing the polyvinyl alcohol resin layer into contact with a dyeing solution containing the dichroic dye; Are included in this order. After the dyeing step (S30), usually, a polarizer layer is formed through a crosslinking step (S35) in which a crosslinking treatment is further performed.

  Furthermore, in order to produce a polarizing plate or the like, a cleaning / drying step (S40) for cleaning and drying the double-sided laminated film, a protective film is laminated on both sides or one side of the double-sided laminated film, Protective film bonding step for obtaining a composite film (S50), drying step for drying a double-sided adhesive film or a single-sided adhesive film (S60), and peeling for peeling the polarizing plate from the double-sided adhesive film or the single-sided adhesive film Step (S70) is performed in this order.

  The manufacturing method of the light-polarizing laminated film of this invention forms a polyvinyl alcohol-type resin layer not only on the single side | surface of a base film but on both surfaces. By this manufacturing method, two polarizing plates can be manufactured simultaneously.

<Each manufacturing process>
Hereinafter, based on FIG. 1 and FIG. 2, each process of S10-S70 is demonstrated in detail.

[Resin Layer Forming Step (S10)]
Here, the base film 1 and the polyvinyl alcohol resin layer are formed by forming the polyvinyl alcohol resin layers (the first polyvinyl alcohol resin layer 21 and the second polyvinyl alcohol resin layer 22) on both surfaces of the base film 1. A double-sided laminated film 202 composed of 21 and 22 is obtained.

  Materials suitable for the base film 1 are as described in the description of the configuration of the polarizing laminated film. In addition, it is preferable to use the base film 1 that can be stretched in a temperature range suitable for stretching the polyvinyl alcohol-based resin. It is preferable that the material which comprises the two polyvinyl alcohol-type resin layers 21 and 22 formed in both surfaces of the base film 1 is the same material. By using the same material, it becomes easy to adjust the polarization performance of the polarizer layer formed thereby.

  Moreover, it is preferable that the polyvinyl alcohol-type resin layers 21 and 22 in both surfaces of the double-sided laminated film after extending | stretching are comparable thickness. The specific thickness of the polyvinyl alcohol resin layers 21 and 22 formed in the resin layer forming step (S10) is preferably more than 3 μm and not more than 30 μm, and more preferably 5 to 20 μm. When the initial thickness of the resin layer is 3 μm or less, it is not preferable because it becomes too thin after stretching and the dyeability is significantly deteriorated. On the other hand, if the thickness exceeds 30 μm, the thickness of the finally obtained polarizer layer may exceed 10 μm, which is not preferable.

  The polyvinyl alcohol resin layers 21 and 22 are preferably formed by applying a polyvinyl alcohol resin solution obtained by dissolving polyvinyl alcohol resin powder in a good solvent on one surface of the base film 1 and removing the solvent. It is formed by evaporating and drying. By forming the polyvinyl alcohol resin layers 21 and 22 in this manner, the polyvinyl alcohol resin can be made thin. As a method of coating a polyvinyl alcohol resin solution on a base film, a wire bar coating method, a reverse coating, a roll coating method such as gravure coating, a die coating method, a comma coating method, a lip coating method, a spin coating method, a screen A known method such as a coating method, a fountain coating method, a dipping method, or a spray method can be appropriately selected and employed. A drying temperature is 50-200 degreeC, for example, Preferably it is 60-150 degreeC. The drying time is, for example, 2 to 20 minutes.

  The application of the polyvinyl alcohol-based resin layer to both surfaces of the base film 1 can be performed one side at a time using the above method, or using a dipping method, a spray coating method, or other special equipment, A polyvinyl alcohol-type resin layer can also be apply | coated to both surfaces of a base film simultaneously.

  Moreover, in order to improve the adhesiveness of the base film 1 and the polyvinyl alcohol-type resin layers 21 and 22, a primer layer may be provided between the base film 1 and the polyvinyl alcohol-type resin layers 21 and 22. The primer layer is preferably formed from a composition containing a polyvinyl alcohol-based resin and a crosslinking agent from the viewpoint of adhesion. Materials suitable for the primer layer are as described in the description of the configuration of the polarizing plate.

  When the primer layer is provided, the order of application to the base film 1 is not particularly limited. After the primer layer is formed on both sides of the base film 1, the polyvinyl alcohol resin layers 21 and 22 are further provided on both sides. The primer layer and the polyvinyl alcohol-based resin layer 21 are sequentially formed on one surface of the base film 1 to form the one-area layer film 201, and then the primer layer is formed on the other surface of the base film. The polyvinyl alcohol resin layer 22 may be formed in order.

[Stretching step (S20)]
Here, the double-sided laminated film 202 obtained in the resin layer forming step (S10) is stretched. Preferably, uniaxial stretching is performed so that the stretching ratio is more than 5 times and not more than 17 times. More preferably, it is uniaxially stretched so that the stretch ratio is more than 5 times and not more than 8 times. When the draw ratio is 5 times or less, the polyvinyl alcohol-based resin layer is not sufficiently oriented, and as a result, the degree of polarization of the polarizer layer may not be sufficiently high. On the other hand, when the draw ratio exceeds 17 times, the laminated film is liable to break during stretching, and at the same time, the thickness of the laminated film after stretching becomes unnecessarily thin, and the workability and handling properties in the subsequent process are lowered. There is a fear. The stretching process in the stretching step (S20) is not limited to stretching in one stage, and can be performed in multiple stages. In this case, the second and subsequent stretching steps may be performed in the stretching step (S20), or may be performed simultaneously with the dyeing step (S30) and the crosslinking step (S35). Thus, when extending | stretching by multistage, extending | stretching process is performed so that it may become a draw ratio exceeding 5 times combining all the stages of extending | stretching process.

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

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

[Dyeing step (S30)]
Here, the polyvinyl alcohol resin layers 21 and 22 on both sides of the double-sided laminated film 202 are dyed with a dichroic dye. The dichroic dye is as described above.

  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. In addition, the time when one polyvinyl alcohol-based resin layer (first polyvinyl alcohol-based resin layer) in the stretched film is in contact with the dyeing solution is T1, and the other polyvinyl alcohol-based resin layer (second polyvinyl alcohol-based resin layer) is the dyeing solution. If the time of contact with T2 is T2, the following formula (1):
Ratio of contact time difference (%) = (T1-T2) / {(T1 + T2) / 2} × 100 (1)
The ratio of the contact time difference calculated from the absolute value exceeds 4%, preferably 4.5% or more.

  According to the present invention, when the ratio of the contact time difference exceeds 4% in absolute value, the difference between the average values of the two corrected polarizer layers having different transmittances, for example, the visibility corrected single transmittance displayed in% units is 0. Two polarizer layers exceeding 3 points can be obtained simultaneously. Various methods can be selected as a method of adjusting the times T1 and T2 during which the polyvinyl alcohol-based resin layer contacts the dyeing solution. For example, the method of adjusting by designing the size (diameter) of the guide roll, the method of designing and adjusting the contact length with the guide roll by the pass line, the contact length with the guide roll by the lifting roll that can change the position Examples thereof include a method of changing the thickness and a method of adjusting these in combination. Among these, a method of devising a pass line is simple and preferable. However, since it becomes a fixed type and fine adjustment is difficult, an adjustable lifting roll may be used in combination. A specific example of the adjustment method will be described later as the first embodiment.

  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.

  The dyeing treatment can be performed before the stretching process or simultaneously with the stretching process. However, the stretching process is performed on the unstretched film so that the dichroic dye adsorbed on the polyvinyl alcohol resin can be favorably oriented. It is preferable to carry out a dyeing treatment after applying. At this time, it may be simply dyed what has been stretched in advance at the target magnification, or may be stretched again during dyeing and stretched at a low magnification in advance to reach the target magnification in total. . Further, in the case of stretching during the subsequent crosslinking treatment, the total draw ratio at the stage where the dyeing process is completed can be set lower than the target final magnification. In this case, what is necessary is just to adjust suitably so that the target magnification may be reached after a crosslinking process.

[Crosslinking step (S35)]
After the dyeing step (S30), a crosslinking step (S35) for performing a crosslinking treatment is usually provided. The crosslinking treatment is performed, for example, by immersing the laminated film in a solution containing a crosslinking agent (crosslinking solution). Conventionally known substances can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. One kind of these may be used, or two or more kinds may be used in combination.

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

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

  The immersion time of the stretched film in the crosslinking solution is usually preferably from 15 seconds to 20 minutes, and more preferably from 30 seconds to 15 minutes.

  The crosslinking treatment can be performed simultaneously with the dyeing treatment by blending a crosslinking agent in the dyeing solution. Moreover, what was previously extended | stretched by the target magnification may be only bridge | crosslinked, and you may perform a bridge | crosslinking process and extending | stretching simultaneously. You may make it reach | attain the target magnification in total by extending | stretching the stretched film previously extended | stretched by the low magnification by the extending | stretching process again during a crosslinking process.

  Through the dyeing step (S30) and the crosslinking step (S35), the polyvinyl alcohol resin layers 21 and 22 have a function as the polarizer layers 31 and 32, and the double-sided polarizing laminate film 302 is obtained.

[Washing step (S40)]
Next, it is preferable to perform a cleaning process for cleaning the double-sided polarizing laminated film 302. As the washing step, a water washing treatment can be performed. The water washing treatment can be usually performed by immersing a stretched film in pure water such as ion exchange water or distilled water as a washing liquid. The water washing temperature is usually in the range of 3 to 50 ° C, preferably 4 to 20 ° C.

  The washing step may be a combination of a washing treatment with an iodide solution and a water washing treatment, and a solution appropriately mixed with a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, or propanol can also be used as a washing solution. Moreover, you may provide the process of draining using a nip roll, an air knife, etc. after the washing | cleaning process.

  The immersion time of the stretched film in the cleaning liquid in the cleaning step is usually 2 to 300 seconds, preferably 3 to 240 seconds.

  It is preferable to dry the double-sided polarizing laminate film after the washing step. 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.

[Protective film pasting step (S50)]
Here, a protective film is bonded to one surface or both surfaces of the double-sided polarizing laminate film 302 that has undergone the above-described steps, that is, the surface of one polarizer layer or the surfaces of both polarizer layers. In FIG. 2, the method of bonding the protective films 41 and 42 to the surface of both the polarizer layers 31 and 32 is shown typically. 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 configuration 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 the thickness is 3 to 25 μm, it has good processability and is also suitable for suppressing the dimensional change of the polarizing film. When the pressure-sensitive adhesive layer is less than 1 μm, the tackiness is lowered, and when it exceeds 40 μm, problems such as the pressure-sensitive adhesive protruding easily occur.

  The method of forming the pressure-sensitive adhesive layer on the protective film or the polarizer is not particularly limited, and a solution containing each component including the above-mentioned base polymer is applied to the protective film surface or the polarizer layer surface, After forming the pressure-sensitive adhesive layer by drying, it may be bonded to a separator or other types of film, or after forming the pressure-sensitive adhesive layer on the separator, it is laminated on the protective film surface or the polarizer layer surface. Also good. Further, when forming the pressure-sensitive adhesive layer on the surface of the protective film or the polarizer layer, if necessary, the protective film or the polarizer layer surface, or one or both of the pressure-sensitive adhesive layers may be subjected to an adhesion treatment such as corona treatment. Good.

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

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

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

  After drying, it may be further cured for about 12 to 600 hours at room temperature or a slightly higher temperature, for example, a temperature of 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, casting method, Mayer bar coating method, gravure coating method, comma coater method, doctor plate method, die coating method Examples of the method include applying an adhesive to the adhesive surface of the film by a dip coating method, a spraying method, and the like, and superimposing two films. The casting method is a method in which two films as an object to be coated are moved in a substantially vertical direction, generally in a horizontal direction, or in an oblique direction between the two, and an adhesive is allowed to flow down and spread on the surface. is there.

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

  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. The saponification treatment is performed by immersing the film 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 to be cm ² . By appropriately selecting the irradiation intensity within this range, the reaction time does not become too long, and the yellowing of the adhesive and the deterioration of the polarizing plate are caused by the heat radiated from the light source and the heat generated when the photocurable adhesive is cured. The possibility of occurring can be suppressed. The light irradiation time to the photocurable adhesive is applied according to the photocurable adhesive to be cured and is not particularly limited, but is expressed as a product of the irradiation intensity and the irradiation time. It is preferable that the integrated light amount is set to be 10 to 10,000 mJ / cm ² . By appropriately selecting the amount of light integrated into the photocurable adhesive within this range, it is possible to generate a sufficient amount of active species derived from the polymerization initiator to allow the curing reaction to proceed more reliably and to increase the irradiation time. However, good productivity can be maintained. The thickness of the adhesive layer after curing is usually about 0.001 to 5 μm, preferably 0.01 μm or more, and preferably 2 μm or less.

  When curing the photocurable adhesive between the polarizer layer and the protective film, etc. by irradiation with active energy rays, the polarization degree, transmittance and hue of the polarizer layer, and transparency of the protective film, etc. It is preferable to perform the curing under conditions that do not deteriorate the functions of the plate.

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

[Peeling step (S70)]
After a drying process (S60), from the base film 1, the laminated body of the polarizer layer 31 and the protective film 41, or the laminated body of the polarizer layer 32 and the protective film 42 from a double-sided bonding film or a single-sided bonding film. The peeling process (S70) which peels and obtains polarizing plates 501a and 501b is performed. The peeling method of a laminated body 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 drying step (S60), it may be peeled off as it is, or after winding up once in a roll shape, a separate peeling step may be provided for peeling. The polarizing plates 501a and 501b can be provided as a polarizing plate set. For example, the polarizing plates 501a and 501b can be provided as a polarizing plate set disposed on both sides of a liquid crystal cell of a liquid crystal display device. The polarizing plates 501a and 502a having the protective films 41 and 42 bonded on one side can be used as they are, the surface of the polarizer layer 31 opposite to the surface on which the protective film 41 of the polarizing plate 501a is provided, A protective film or another optical layer to be described later can also be laminated on the surface of the polarizer layer 32 opposite to the surface on which the protective film 42 of the plate 501b is provided.

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

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

  For example, DBEF (manufactured by 3M, available from Sumitomo 3M Co., Ltd. in Japan) is a commercially available product that corresponds to a reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties. , APF (manufactured by 3M, available from Sumitomo 3M Co., Ltd. in Japan) and the like. Examples of the viewing angle compensation film include an optical compensation film in which a liquid crystal compound is applied to the substrate surface, and is oriented / fixed, a retardation film made of a polycarbonate resin, a retardation film made of a cyclic polyolefin resin, and the like. . Commercially available products corresponding to the optical compensation film in which the liquid crystal compound is coated on the substrate surface and oriented / fixed include WV film (manufactured by FUJIFILM Corporation), NH film (JX Nippon Mining & Energy Corporation) And NR film (manufactured by JX Nippon Oil & Energy Corporation). Commercial products corresponding to retardation films made of cyclic polyolefin resin include Arton Film (manufactured by JSR Corporation), Essina (manufactured by Sekisui Chemical Co., Ltd.), Zeonore Film (manufactured by Nippon Zeon Corporation). Etc.

[Visibility corrected single transmittance]
The average value of the visibility corrected single transmittance of the polarizer layers 31 and 32 in the double-sided polarizing laminated film 302 is the difference when expressed in% units (the average value of the single visibility corrected visibility of the polarizing layer 31 is polarized. The value obtained by subtracting the average value of the visibility correction single transmittance of the layer 32) is preferably more than 0.3 point, and more preferably 0.45 point or more. Since the difference in the average value of the visibility corrected single transmittance is included in such a range, the two polarizing plates 501a and 501b each including the polarizer layers 31 and 32 are polarizing plates having different transmittances. It is suitable as a polarizing plate set for a liquid crystal display device that is desired to be set.

Here, the visibility corrected single transmittance is a numerical value defined by the following equation.
Single transmittance (λ) = 0.5 × (Tp (λ) + Tc (λ))
Here, Tp (λ) is the transmittance (%) of the polarizer layer measured in relation to the linearly polarized light with the incident wavelength λnm and parallel Nicol, and Tc (λ) is the linearly polarized light with the incident wavelength λnm. The transmittance (%) of the polarizer layer measured in a crossed Nicols relationship, both of which are measured values obtained by measuring polarized ultraviolet visible absorption spectra with a spectrophotometer. The single transmittance (λ) obtained for each wavelength is subjected to sensitivity correction called visibility correction, which is referred to as visibility correction single transmittance (Ty). Ty can be easily measured with, for example, a spectrophotometer (model number: V7100) manufactured by JASCO Corporation. In addition, the average value of the visibility corrected single transmittance may be obtained by measuring the visibility corrected single transmittance at a plurality of locations for each of the polarizer layers 31 and 32 and averaging them. It is preferable that the measurement locations be 10 points or more for each of the polarizer layers 31 and 32 in the width direction of the film, that is, the in-plane direction orthogonal to the stretching direction. In the examples described later, the effective width portion in the film width direction was divided into 11, and the visibility corrected single transmittance was measured for the 11 points to obtain the average value.

  In the measurement of the visibility corrected single transmittance, the absolute value of the visibility corrected single transmittance slightly fluctuates due to the difference in interface reflectance depending on the presence or absence of the protective film and the type of protective film. However, in the present invention, since the difference in the visibility corrected single transmittance between the two polarizer layers is important, the upper and lower absolute values are not so important. In other words, if the difference is obtained after measuring both with the same configuration, it can be regarded as a difference in the visibility corrected single transmittance of the two polarizer layers.

[Dyeing process, crosslinking process, washing process]
FIG. 3 is a cross-sectional view schematically showing an example of a method for treating a stretched film in the dyeing process, the crosslinking process, and the washing process of the present invention. The dyeing tank 10 that holds the dyeing solution, the crosslinking tank 20 that holds the cross-linking solution, and the cleaning tank 30 that holds the cleaning liquid are arranged in order, and the double-sided laminated film 202 is placed in the dyeing tank 10 via the guide roll 101. It is guided and conveyed in the dyeing tank 10 (within the dyeing solution) while contacting a plurality of guide rolls arranged in the dyeing tank 10, and thereafter guided into the crosslinking tank 20 through the guide roll 102, and the crosslinking tank 20. The guide is disposed in the crosslinking tank 20 (in the crosslinking solution) while being in contact with a plurality of guide rolls disposed in the guide, and then guided into the cleaning tank 30 via the guide roll 103 and disposed in the cleaning tank 30. It is conveyed in the cleaning tank 30 (in the cleaning liquid) while being in contact with the roll, and then conveyed to the next process via the guide roll 104.

[Method for adjusting the contact time of the polyvinyl alcohol resin layer to the dyeing solution]
Hereinafter, a specific method for adjusting the contact time of the first polyvinyl alcohol resin layer 21 and the second polyvinyl alcohol resin layer 22 in the double-sided laminated film 202 to the dyeing solution will be described.

(First embodiment)
FIG. 4 is a cross-sectional view schematically showing the dyeing tank of the first embodiment. In the dyeing tank 10, five guide rolls having substantially the same diameter are arranged, three guide rolls 11A, 12A, 13A are arranged at substantially equal intervals on the lower side, and two guide rolls 11B, 12B are arranged on the upper side. Are arranged at substantially equal intervals. The double-sided laminated film 202 is guided into the dyeing tank 10 and brought into contact with the dyeing solution, and is conveyed through the dyeing solution so as to alternately contact the lower guide roll and the upper guide roll. More specifically, the lower guide roll 11A is first contacted downward, then the upper guide roll 11B is upper, the lower guide roll 12A is lower, and the upper guide roll 12B is upper. The lower guide roll 13A is sequentially brought into contact with the lower side in order and then conveyed out of the dyeing tank 10. In FIG. 4, the contact portion between each guide roll and the double-sided laminated film 202 is indicated by a dotted line.

  The first polyvinyl alcohol-based resin layer 21 is formed on one surface of the double-sided laminated film 202, and the second polyvinyl alcohol-based resin layer 22 is formed on the other surface. The first polyvinyl alcohol-based resin layer 21 and the second polyvinyl alcohol-based resin layer 22 may be transported so that whichever is the upper and which is the lower, but here the first polyvinyl alcohol-based resin layer 21 is The case where it exists in the upper part and the 2nd polyvinyl alcohol-type resin layer 22 exists below is demonstrated.

  As can be seen from FIG. 4, in the double-sided laminated film 202, the lower guide rolls 11A, 12A, and 13A are in contact with the first polyvinyl alcohol-based resin layer 21 above the double-sided laminated film 202, and the upper guide roll 11A. The rolls 11 </ b> B and 12 </ b> B are conveyed so that the second polyvinyl alcohol-based resin layer 22 located below the double-sided laminated film 202 is in contact therewith.

  In the dyeing tank 10, while the first polyvinyl alcohol resin layer 21 or the second polyvinyl alcohol resin layer 22 is in contact with the guide roll, it can be regarded as not in contact with the dyeing solution. The contact time of the polyvinyl alcohol resin layer 21 and the second polyvinyl alcohol resin layer 22 to the dyeing solution can be adjusted by changing the contact time to the guide roll. That is, the time T1 in contact with the dyeing solution of the first polyvinyl alcohol-based resin layer 21 is changed from the immersion time of the double-sided laminated film 202 into the dyeing solution to the guide rolls 11A, 12A, 13A of the first polyvinyl alcohol-based resin layer 21. The time T2 for contacting the dyeing solution of the second polyvinyl alcohol-based resin layer 22 is a time obtained by subtracting the contact time of the second polyvinyl alcohol-based resin layer 22 from the immersion time of the double-sided laminated film 202 in the dyeing solution. This is the time obtained by subtracting the contact time to the guide rolls 11B and 12B. The contact time of the first polyvinyl alcohol-based resin layer 21 or the second polyvinyl alcohol-based resin layer 22 to the guide roll is calculated by calculating or measuring the distance of the contact portion and dividing the distance by the conveyance speed. be able to.

  According to the arrangement of the guide rolls in the dyeing tank 10 shown in FIG. 4, the lower guide roll is one more than the upper guide roll, and the second polyvinyl alcohol-based resin layer 21 is in contact with the guide roll, It is easy to provide a desired difference in the time when the polyvinyl alcohol-based resin layer 22 contacts the guide roll, and the ratio (%) of the contact time difference shown in the formula (1) can be adjusted to exceed 4% in absolute value. .

[Example 1]
Two polarizing plates 501a and 501b were produced from the double-sided polarizing laminate film 302 as shown in the flowchart of FIG.

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

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

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

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

  Further, the same coating treatment is performed on the surface of the primer layer formed on the other surface of the base film 1, and the first polyvinyl alcohol resin layer 21, the base film 1, and the second polyvinyl alcohol resin layer. A double-sided laminated film 202 consisting of 22 was produced. At this time, the thicknesses of the polyvinyl alcohol resin layers 21 and 22 (before stretching) were 10.5 μm and 10.2 μm, respectively.

(Stretching process)
The double-sided laminated film 202 was subjected to 5.8-fold free end uniaxial stretching at 160 ° C. using an inter-roll longitudinal stretching machine. The thicknesses of the two polyvinyl alcohol resin layers of the double-sided laminated film after stretching were 5 μm ± 0.1 μm.

(Dyeing process)
The double-sided laminated film after stretching was immersed in a dyeing solution that is a mixed aqueous solution of iodine and potassium iodide at 30 ° C. to perform a dyeing process. At this time, in the dyeing tank, a guide roll is arranged in the dyeing tank as shown in FIG.
Total residence length of double-sided laminated film in dyeing solution: 4700mm
Conveyance speed: 1.78m / min
Total residence time of double-sided laminated film in dyeing solution:
4.7 m / [(1.78 / 60) m / sec] ≈158.427 sec
Guide roll diameter: 125 mm
The length of the first polyvinyl alcohol-based resin layer 21 contacting the lower guide rolls 11A, 12A, 13A and the length of the second polyvinyl alcohol-based resin layer 22 contacting the upper guide rolls 11B, 12B are adjusted. Then, the time for each to contact the guide roll is calculated, and the value described in the column “Contact time to the guide roll” in Table 1 is calculated. The pass line was set so as to be the value described in the column of “Contact time with staining solution”.

Thereafter, excess iodine solution was washed away with pure water at 10 ° C. Subsequently, it was immersed for 600 second in the bridge | crosslinking solution which is a 76 degreeC mixed aqueous solution of boric acid and potassium iodide. The mixing ratio of the dyeing solution and the crosslinking solution is
<Dyeing solution>
Water: 100 parts by weight Iodine: 0.35 parts by weight Potassium iodide: 10 parts by weight <Crosslinking solution>
Water: 100 parts by weight Boric acid: 9.5 parts by weight Potassium iodide: 5 parts by weight

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

(Protective film bonding process)
Polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree 1800, trade name: KL-318) was dissolved in 95 ° C. hot water to prepare an aqueous solution having a concentration of 3% by weight. The resulting aqueous solution was mixed with a crosslinking agent (manufactured by Taoka Chemical Co., Ltd., trade name: Sumire's Resin 650) at a ratio of 1 part by weight to 2 parts by weight of the polyvinyl alcohol powder to obtain an adhesive solution. After applying the above-mentioned polyvinyl alcohol-based adhesive on both sides of the double-sided polarizing laminate film obtained above, protective films (TAC: KC4UY manufactured by Konica Minolta Opto Co., Ltd.) 41 and 42 were bonded to both sides, and 80 ° C. Was dried for 5 minutes to obtain a double-sided laminated film 402 comprising five layers of the protective film 41, the polarizer layer 31, the base film 1, the polarizer layer 32, and the protective film 42.

(Drying process and peeling process)
The 1st polarizing plate 501a which consists of the polarizer layer 31 and the protective film 41 was peeled from the double-sided bonding film 402. FIG. The base film 1 was peeled off from the remaining film (the base film 1, the polarizer layer 32 and the protective film 42) to obtain a second polarizing plate 501 b consisting of the polarizer layer 32 and the protective film 42. .

  The base film 1 was easily peeled off from the polarizing plates 501a and 501b formed on both surfaces thereof. The thicknesses of the polarizer layers 31 and 32 of the obtained two polarizing plates 501a and 501b are both 5. It was μm ± 0.1 μm.

[Example 2]
Two polarizing plates 501a and 501b were produced from the double-sided polarizing laminate film 302 as shown in the flowchart of FIG. Example 2 is different from Example 1 only in the pass line in the dyeing process, and this point will be described below.

In the dyeing tank of the dyeing process of Example 2, as shown in FIG. 4, a guide roll is arranged in the dyeing tank,
Total residence length of double-sided laminated film in dyeing solution: 4700mm
Conveyance speed: 1.78m / min
Total residence time of double-sided laminated film in dyeing solution:
4.7 m / [(1.78 / 60) m / sec] ≈158.427 sec
Guide roll diameter: 200 mm
The length of the first polyvinyl alcohol-based resin layer 21 contacting the lower guide rolls 11A, 12A, 13A and the length of the second polyvinyl alcohol-based resin layer 22 contacting the upper guide rolls 11B, 12B are adjusted. Then, the time for each to contact the guide roll is calculated, and the value described in the column “Contact time to the guide roll” in Table 1 is calculated. The pass line was set so as to be the value described in the column of “Contact time with staining solution”.

[Measurement of polarization performance of polarizing plate]
The polarizing performance of the polarizing plate obtained in the example was measured with a spectrophotometer (V7100) manufactured by JASCO Corporation. In the measurement, the incident direction of light was from the polarizer layer side. Table 1 shows the difference between the average value of the visibility corrected single transmittance (Ty) and the average value of the visibility corrected single transmittance of the two polarizing plates 501a and 501b. In addition, the average value of the visibility corrected single transmittance (Ty) of the two polarizing plates is an average value of values obtained by dividing the effective width portion in the film width direction into 11 for each polarizing plate and measuring the 11 points. is there. In addition, since the same protective film is used for the two polarizing plates, there is no difference in the single transmittance. Therefore, the difference in the average value of the single-passivity corrected single transmittance (Ty) of the polarizing plate is the same as that of the polarizing layer. It can be regarded as a difference in average value of sensitivity corrected single transmittance (Ty).

  As can be seen from the results shown in Table 1, the ratio of the contact time difference to the staining solution (in Table 1, the value in the column of “(T1−T2) / {(T1 + T2) / 2} × 100 (%))” is an absolute value. If the difference is more than 4% (Examples 1 and 2), the difference in the transmittance correction single transmittance displayed in% units of the two polarizing plates exceeds 0.3 points, and the difference in transmittance is large. A polarizing plate could be obtained at the same time.

  DESCRIPTION OF SYMBOLS 1 Base film, 10 Dyeing tank, 11A, 12A, 13A Lower guide roll, 11B, 12B Upper guide roll, 20 Cross-linking tank, 21 First polyvinyl alcohol-based resin layer, 22 Second polyvinyl alcohol-based resin layer, 201 Single-area layer film, 202 Double-sided laminated film, 30 Cross-linking tank, 31, 32 Polarizer layer, 302 Double-sided polarizing laminated film, 41, 42 Protective film, 401 Single-sided laminated film, 402 Double-sided laminated film, 501a, 501b Polarized light Board.

Claims (8)

A method for producing a polarizing laminate film comprising a base film and two polarizer layers respectively formed on both sides of the base film,
A resin layer forming step of forming a first polyvinyl alcohol-based resin layer on one surface of the base film and forming a second polyvinyl alcohol-based resin layer on the other surface to obtain a laminated film;
A stretching step of stretching the laminated film;
The first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer of the laminated film after stretching are brought into contact with a dye solution containing a dichroic dye and dyed with the dichroic dye to thereby form two polarized lights. A dyeing step for forming a child layer,
In the dyeing step, when the time when the first polyvinyl alcohol resin layer is in contact with the dye solution is T1, and the time when the second polyvinyl alcohol resin layer is in contact with the dye solution is T2, the following formula:
Ratio of contact time difference (%) = (T1-T2) / {(T1 + T2) / 2} × 100
The manufacturing method of a light-polarizing laminated film in which the ratio of the contact time difference calculated from is over 4% in absolute value. The percentage of contact time between difference is an absolute value of 4.5% or more, the production method of the polarizing laminate film according to claim 1. The dyeing step transports the laminated film in the dyeing solution while bringing the first polyvinyl alcohol resin layer and / or the second polyvinyl alcohol resin layer into contact with a guide roll,
Adjusting the time when the first polyvinyl alcohol-based resin layer and the second polyvinyl alcohol-based resin layer are in contact with the guide roll, the time T1 when the first polyvinyl alcohol-based resin layer is in contact with the dyeing solution, 3. The polarizing laminate film according to claim 1, wherein a time T <b> 2 in which the second polyvinyl alcohol-based resin layer is in contact with the dyeing solution is adjusted so that a ratio of the contact time difference is in a desired numerical range. Production method.   The manufacturing method of the light-polarizing laminated film as described in any one of Claims 1-3 which has the bonding process which bonds a protective film on the surface of at least one said polarizer layer after the said dyeing | staining process.   The manufacturing method of the polarizing laminated film of Claim 4 which bonds a protective film on the surface of said two polarizer layers in the said bonding process. A method for producing a polarizing plate comprising a polarizer layer and a protective film,
A polarizing plate obtained by the production method according to claim 4 or 5, wherein a laminate of the polarizer layer and the protective film in the polarizing laminated film is peeled off from the base film and a polarizing plate. The manufacturing method of a polarizing plate which has the peeling process of obtaining. A base film, and two polarizer layers formed on both surfaces of the base film from a polyvinyl alcohol-based resin and adsorbed and oriented with the dichroic dye by uniaxial stretching and dyeing with a dichroic dye ,
The two polarizer layers are polarizing laminated films in which a difference in average value of visibility-adjusted single transmittances expressed in% unit exceeds 0.3 points.   The polarizing laminated film according to claim 7, wherein the difference between the average values of the visibility-corrected single transmittances displayed in units of% is 0.45 points or more between the two polarizer layers.

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