WO2013146644A1 - Laminate film, method for producing polarizing laminate film, and method for producing polarizing plate - Google Patents

Abstract

Provided are: a laminate film provided with a substrate film, which comprises a thermoplastic resin, and a polyvinyl alcohol resin layer formed by means of coating onto at least one surface of the substrate film, the substrate film having a tensile elasticity at 80°C of at least 140 MPa; a polarizing laminate film using the laminate film; and a method for producing a polarizing plate. Preferably, of the substrate film, the surface layer of at least the surface to which the polyvinyl alcohol resin film has been formed is configured from a crystalline thermoplastic resin having a crystallinity of at least 58%.

Description

LAMINATED FILM, POLARIZING LAMINATED FILM MANUFACTURING METHOD AND POLARIZING PLATE MANUFACTURING METHOD

The present invention relates to a polarizing laminated film having a polarizer layer or a laminated film that can be suitably used as a production intermediate of a polarizing plate. Moreover, this invention relates to the manufacturing method of a light-polarizing laminated film, and the manufacturing method of a polarizing plate.

The polarizing plate is widely used as a polarized light supplying element and a polarized light detecting element in a liquid crystal display device. Conventionally, as a polarizing plate, a polarizing film made of a polyvinyl alcohol resin and a protective film made of triacetyl cellulose or the like bonded to an adhesive is used. With the development of mobile devices such as personal computers and mobile phones, as well as the development of large televisions, there is a demand for thinner and lighter polarizing plates.

However, the polarizing film is produced by stretching and dyeing a polyvinyl alcohol-based resin film original (usually about 75 μm in thickness), and the thickness of the stretched film is usually about 30 μm. Thinning beyond this has been difficult due to productivity problems such as the film during stretching being easily broken.

Therefore, after forming a polyvinyl alcohol resin layer by applying a coating liquid containing a polyvinyl alcohol resin on the base film to obtain a laminated film, the base film is stretched and then dyed. Thus, a method for producing a laminate (polarizing laminate film) having a polarizer layer and a polarizing plate using a polyvinyl alcohol-based resin layer as a polarizer layer has been proposed [for example, JP 2000-338329 A ( Patent Document 1), Japanese Patent Application Laid-Open No. 2009-098653 (Patent Document 2), Japanese Patent Application Laid-Open No. 2009-93074 (Patent Document 3), and Japanese Patent Application Laid-Open No. 2011-1000016 (Patent Document 4). According to this method, a thinner polyvinyl alcohol-based resin layer can be obtained than when a polyvinyl alcohol-based resin film is used.

JP 2000-338329 A JP 2009-0986653 A JP 2009-093074 A JP 2011-1000016 A

In the method including the step of forming a polyvinyl alcohol-based resin layer on a base film by applying a coating liquid containing a polyvinyl alcohol-based resin as described above to obtain a laminated film, a layer made of the coating liquid The process of drying the base film in which (coating layer) was formed and removing the solvent in a coating layer becomes essential. However, during the drying, defects such as wrinkles and folds may occur in the base film, or the coating solution may accumulate in the defective portions, resulting in poor drying.

Accordingly, an object of the present invention is a laminated film comprising a polyvinyl alcohol-based resin layer formed by coating a coating liquid containing a polyvinyl alcohol-based resin on a substrate film and subsequent drying. It is an object of the present invention to provide a laminated film in which defects such as wrinkles or folds that may occur in the film and defects in drying of the coating layer associated therewith are sufficiently suppressed.

Another object of the present invention is to form a laminated film by forming a polyvinyl alcohol-based resin layer by coating a substrate liquid containing a polyvinyl alcohol-based resin on a base film and subsequent drying to obtain a laminated film. And a method for producing a polarizing laminated film or polarizing plate using the polyvinyl alcohol resin layer as a polarizer layer by dyeing, and defects such as wrinkles or folds in the substrate film during drying and the coating layer associated therewith An object of the present invention is to provide a method capable of efficiently producing a polarizing laminated film or a polarizing plate without causing poor drying.

The present invention is as follows.
[1] A base film made of a thermoplastic resin and a polyvinyl alcohol-based resin layer formed by coating on at least one surface of the base film, and the base film has a tensile modulus at 80 ° C. Is a laminated film of 140 MPa or more.

[2] In the base film, at least the surface layer on which the polyvinyl alcohol-based resin layer is formed is composed of a crystalline thermoplastic resin, and the surface layer composed of the crystalline thermoplastic resin is composed of 58% or more crystals. The laminated film according to [1], having a degree of conversion.

[3] The laminated film according to [2], wherein the surface layer composed of the crystalline thermoplastic resin of the base film contains a nucleating agent.

[4] The laminated film according to any one of [1] to [3], wherein the polyvinyl alcohol-based resin layer has a thickness of 3 to 30 μm.

[5] Used to produce a polarizing laminated film by uniaxially stretching the laminated film and then dyeing the polyvinyl alcohol-based resin layer with a dichroic dye to form a polarizer layer. [1] The laminated film according to any one of to [4].

[6] A stretching step of obtaining a stretched film by uniaxially stretching the laminated film according to any one of [1] to [4];
A dyeing step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer;
A method for producing a polarizing laminate film.

[7] A base film preparation step for preparing a base film made of a thermoplastic resin film having a tensile elastic modulus at 80 ° C. of 140 MPa or more;
After applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film, a resin layer forming step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer by drying;
A stretching process for obtaining a stretched film by uniaxially stretching the resulting laminated film;
A dyeing step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer;
A method for producing a polarizing laminate film.

[8] A base film preparation step for obtaining a base film by heat-treating the thermoplastic resin film;
After applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the obtained base film, a resin layer forming step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer by drying,
A stretching process for obtaining a stretched film by uniaxially stretching the resulting laminated film;
A dyeing step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer;
With
The said base film preparation process is a manufacturing method of a light-polarizing laminated film including the process of heat-processing the said thermoplastic resin film at the temperature more than the drying temperature in the said resin layer formation process.

[9] Between the base film preparation step and the resin layer formation step, the primer layer forming coating solution is applied to the surface of the base film on which the coating solution is applied, and then dried. Further comprising a primer layer forming step of forming a primer layer by
The said base film preparation process is a manufacturing method of the polarizing laminated film as described in [8] including the process of heat-processing the said thermoplastic resin film at the temperature more than the drying temperature in the said primer layer formation process.

[10] A base material for preparing a base film comprising a thermoplastic resin film in which a surface layer on which a polyvinyl alcohol-based resin layer is formed at least in the next step is composed of a crystalline thermoplastic resin containing a nucleating agent A film preparation process;
After applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film, a resin layer forming step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer by drying;
A stretching process for obtaining a stretched film by uniaxially stretching the resulting laminated film;
A dyeing step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer;
A method for producing a polarizing laminate film.

[11] The method for producing a polarizing laminated film according to any one of [6] to [10], wherein the laminated film is uniaxially stretched at a draw ratio of more than 5 times.

[12] The method for producing a polarizing laminated film according to any one of [6] to [11], wherein the polyvinyl alcohol-based resin layer in the laminated film has a thickness of 3 to 30 μm.

[13] A step of preparing a polarizing laminated film obtained by the production method according to any one of [6] to [12];
A step of bonding a protective film on the polarizer layer in the polarizing laminated film to obtain a bonding film;
A step of peeling the substrate film from the obtained bonding film;
The manufacturing method of a polarizing plate provided with.

According to the present invention, by using a base film excellent in heat resistance having a tensile elastic modulus at 80 ° C. of 140 MPa or more, defects such as wrinkles or folds that may occur in the base film and coating associated therewith It is possible to provide a laminated film in which problems such as poor drying of layers are sufficiently suppressed. The laminated film according to the present invention can be suitably used as a production intermediate for a polarizing laminated film or a polarizing plate.

According to the present invention, a laminated film can be produced without the above-mentioned problems by using a base film excellent in heat resistance having a tensile elastic modulus at 80 ° C. of 140 MPa or more. Using this laminated film, a polarizing laminated film or a polarizing plate can be efficiently produced without impairing stretchability and dyeability.

It is a schematic sectional drawing which shows an example of the laminated constitution of the laminated film which concerns on this invention. It is a schematic sectional drawing which shows an example of the laminated constitution of the stretched film which concerns on this invention. It is a schematic sectional drawing which shows an example of the layer structure of the light-polarizing laminated film which concerns on this invention. It is a flowchart which shows preferable embodiment of the manufacturing method of the laminated | multilayer film which concerns on this invention, a polarizing laminated film, and a polarizing plate.

Hereinafter, the laminated film according to the present invention and the manufacturing method thereof, the manufacturing method of the polarizing laminated film, and the manufacturing method of the polarizing plate will be described in detail with reference to embodiments.

<Laminated film>
FIG. 1 is a schematic cross-sectional view showing an example of a layer configuration of a laminated film according to the present invention. A laminated film 100 shown in FIG. 1 includes a base film 101 made of a thermoplastic resin and a polyvinyl alcohol resin layer 102 laminated on the base film 101. The laminated film of the present invention may be provided with the polyvinyl alcohol resin layer 102 only on one side of the base film 101 as in the example shown in FIG. The resin layer 102 may be provided. Moreover, the laminated film of the present invention may have a primer layer (not shown) interposed between the base film 101 and the polyvinyl alcohol-based resin layer 102.

The base film 101 exhibits high heat resistance, and specifically, the tensile elastic modulus at 80 ° C. is 140 MPa or more.

The polyvinyl alcohol-based resin layer 102 is a layer formed by applying a coating liquid containing a polyvinyl alcohol-based resin to the base film 101 and then drying it. By forming the polyvinyl alcohol-based resin layer 102 by coating, the thickness of the polyvinyl alcohol-based resin layer 102 can be reduced to 30 μm or less, preferably 20 μm or less, more preferably 10 μm or less.

Since the laminated film of the present invention has a large tensile elastic modulus at 80 ° C. of 140 MPa or more, it effectively suppresses defects such as wrinkles or folds during drying of the coating layer and associated drying failure of the coating layer. Has been.

As a method for suppressing the above problems, a thermoplastic resin having an extremely high melting point (or glass transition temperature) is used for the base film 101, or a stretched film made of an amorphous thermoplastic resin is used. It is recalled that it is used for the base film 101. However, in the former case, stretching of the laminated film 100 can be extremely difficult, and in the latter case, the orientation of the polymer chain of the thermoplastic resin constituting the base film 101 is strong, so It may have an adverse effect on stretchability.

The laminated film of the present invention can be suitably used as a production intermediate for a polarizing laminated film having a polarizer layer or a polarizing plate, as will be described in detail later. For example, when the laminated film 100 shown in FIG. 1 is used as a production intermediate, the laminated film 100 is uniaxially stretched together with the base film 101 and stretched with the stretched film 200 (stretched with the stretched base film 201) shown in FIG. And a stretching step S30 for obtaining a polarizer layer by dyeing the polyvinyl alcohol resin layer 202 of the obtained stretched film 200 with a dichroic dye. Through step S40, a polarizing laminated film 300 in which a polarizer layer 302 is laminated on a base film 301 as shown in FIG. 3 can be manufactured.

The polarizing plate is a bonding step S50 for bonding a protective film on the polarizer layer 302 of the polarizing laminated film 300 to obtain a bonding film, and a peeling step for peeling the base film 301 from the obtained bonding film. It can be manufactured through S60.

By using a laminated film in which the above problems are suppressed, a polarizing laminated film and a polarizing plate can be produced without impairing stretchability and dyeability.

[1] Base Film The base film 101 is a film made of a thermoplastic resin having a tensile elastic modulus at 80 ° C. of 140 MPa or more. From the viewpoint of more effectively suppressing the above-described problems during drying of the coating layer, the tensile elastic modulus at 80 ° C. is preferably 150 MPa or more, more preferably 155 MPa or more.

The tensile elastic modulus of the base film 101 can be obtained by cutting out a test piece of a predetermined size from the base film 101 and performing a tensile test. Moreover, in order to obtain | require the tensile elasticity modulus in 80 degreeC, the tensile testing machine provided with a thermostat is used. In Examples described later, a tensile test was performed using a universal testing machine “Autograph AG-I” manufactured by Shimadzu Corporation equipped with a thermostatic bath.

The reason why the tensile elastic modulus at “80 ° C.” is adopted in the present invention is as follows. In this invention, after coating the coating liquid containing a polyvinyl alcohol-type resin on the base film 101, the polyvinyl alcohol-type resin layer 102 is formed by making it dry, and the laminated film 100 is manufactured. If necessary, before forming the polyvinyl alcohol-based resin layer 102, a primer layer-forming coating solution is applied to the surface of the base film 101 on which the polyvinyl alcohol-based resin layer 102 is formed, and then dried. As a result, a primer layer may be formed. Since these drying treatments are generally performed at around 80 ° C., the tensile elastic modulus at 80 ° C. was adopted in the present invention.

As will be described in detail later, as an effective method for obtaining the base film 101 by increasing the tensile elastic modulus of the thermoplastic resin film having a tensile elastic modulus at 80 ° C. of less than 140 MPa to 140 MPa or more,
1) A method of heat-treating a thermoplastic resin film at a temperature equal to or higher than the drying temperature in the subsequent resin layer forming step S20, and 2) A surface layer of a surface on which at least a polyvinyl alcohol-based resin layer is formed in the thermoplastic resin film (FIG. The crystallinity of the surface layer 101a in FIG.
Can be mentioned.

The method 1) can be adopted regardless of whether the thermoplastic resin constituting the thermoplastic resin film is crystalline or amorphous.

Method 2) can be employed when at least the surface layer of the thermoplastic resin film is made of a crystalline thermoplastic resin. According to the study by the present inventors, it has been found that if the crystallinity of the surface layer 101a is 58% or more, the tensile elastic modulus at 80 ° C. of the base film 101 is approximately 140 MPa or more. As a method of increasing the crystallinity of the surface layer 101a to 58% or more, in addition to the method of heat-treating a thermoplastic resin film as in the method 1), a nucleating agent is formed on the surface layer composed of at least a crystalline thermoplastic resin. An effective method is to contain. The degree of crystallinity of the surface layer 101a of the base film 101 is preferably 59% or more, and more preferably 60% or more.

The crystallinity of the surface layer 101a will be described. Generally, this is a value obtained by X-ray diffraction (XRD). From the crystalline scattering integrated intensity (Ic) of the crystal part determined by the X-ray diffraction method and the amorphous scattering integrated intensity (Ia) of the amorphous part, the crystallinity is expressed by the following formula:
Crystallinity = (Ic) / [(Ic) + (Ia)]
Is defined as

Depending on the type of the thermoplastic resin constituting the surface layer 101a of the base film 101, an attenuated total reflection method (Attenuated Total Reflection method: ATR method), a method of measuring specific gravity, or the like can be substituted.

In particular, when the surface layer 101a of the base film 101 is made of a polypropylene resin, the crystallinity can be obtained by the following method. That is, first, using an infrared spectrophotometer, the infrared spectrum of the film surface made of a polypropylene resin is measured by the attenuated total reflection method (ATR method). The ATR method employed here is a method in which the measurement surface of the base film 101 is directly brought into close contact with the germanium crystal prism, and an infrared spectral spectrum relating to a layer of about several μm constituting the extreme surface of the base film 101. Can be obtained. The crystallinity degree X on the surface of a film made of a polypropylene resin is based on the obtained infrared spectroscopic spectrum and is given by
Crystallinity X (%) = 109 × (A ₉₉₈ -A ₉₂₀ ) / (A ₉₇₄ -A ₉₂₀ ) -31.4
(Respectively wherein, A _998, A ₉₇₄ and A ₉₂₀ means the absorbance at the wave number 998 ^-1, 974 cm ^-1 and 920 cm ^-1.)
Can be obtained.

The method and formula for determining the crystallinity of the film surface made of the polypropylene resin shown here are, for example, the following documents:
J. et al. Appl. Polym. Sci. , 2,166 (1959),
Kinichi Shinichi and Iwamoto Rekichi, “Material Analysis by Infrared Method: Fundamentals and Applications”, Kodansha Scientific, August 1986, pp. 214-215,
This method is generally known.

The thermoplastic resin constituting the base film 101 is preferably excellent in transparency, mechanical strength, thermal stability, stretchability and the like. Specific examples of such thermoplastic resins include, for example, polyolefin resins such as chain polyolefin resins and cyclic polyolefin resins (norbornene resins, etc.); polyester resins; (meth) acrylic resins; cellulose triacetate, cellulose Cellulose ester resins such as diacetate; Polycarbonate resins; Polyvinyl alcohol resins; Polyvinyl acetate resins; Polyarylate resins; Polystyrene resins; Polyethersulfone resins; Polysulfone resins; Polyamide resins; And mixtures thereof, copolymers, and the like.

The base film 101 may have a single-layer structure composed of one resin layer composed of one or two or more thermoplastic resins, or a plurality of resin layers composed of one or two or more thermoplastic resins. A laminated multilayer structure may be used.

Examples of the chain polyolefin-based resin include homopolymers of chain olefins such as polyethylene resins and polypropylene resins, and copolymers composed of two or more chain olefins. The base film 101 made of a chain polyolefin-based resin is preferable in that it is easily stretched stably at a high magnification. Among them, the base film 101 is made of polypropylene resin (polypropylene resin which is a homopolymer of propylene, copolymer mainly composed of propylene, etc.), polyethylene resin (polyethylene resin which is a homopolymer of ethylene or ethylene). More preferably, the main component is a copolymer or the like.

The copolymer mainly composed of propylene, which is one example suitably used as the thermoplastic resin constituting the base film 101, is a copolymer of propylene and another monomer copolymerizable therewith.

Examples of other monomers copolymerizable with propylene include ethylene and α-olefin. 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, for example, 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, 4-methyl-1-pentene; and vinylcyclohexane. The copolymer of propylene and other monomers copolymerizable therewith may be a random copolymer or a block copolymer.

The content of the other monomer in the copolymer is, for example, 0.1 to 20% by weight, preferably 0.5 to 10% by weight. The content of other monomers in the copolymer can be determined by measuring infrared (IR) spectrum according to the method described on page 616 of "Polymer Analysis Handbook" (1995, published by Kinokuniya Shoten). Can be sought.

Among these, as the polypropylene resin, a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, or a propylene-ethylene-1-butene random copolymer is preferably used.

It is preferable that the stereoregularity of the polypropylene resin is substantially isotactic or syndiotactic. The base film 101 made of a polypropylene-based resin having substantially isotactic or syndiotactic stereoregularity has relatively good handleability and excellent mechanical strength in a high temperature environment.

The base film 101 may be composed of one kind of chain polyolefin resin, may be composed of a mixture of two or more kinds of chain polyolefin resins, and may be composed of two or more kinds of chain polyolefins. You may comprise from the copolymer of a resin.

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

Various products are commercially available for cyclic polyolefin resins. Examples of commercial products of cyclic polyolefin resins are “Topas” (TOPAS ADVANCED POLYMERS GmbH, available from Polyplastics Co., Ltd.), “Arton” (manufactured by JSR Co., Ltd.). “ZEONOR” (manufactured by Nippon Zeon Co., Ltd.), “ZEONEX” (manufactured by Nippon Zeon Co., Ltd.), “Apel” (manufactured by Mitsui Chemicals, Inc.), and the like.

In addition, film names such as “ESCINA” (manufactured by Sekisui Chemical Co., Ltd.), “SCA40” (manufactured by Sekisui Chemical Co., Ltd.), “ZEONOR FILM” (manufactured by Nippon Zeon Co., Ltd.), etc. You may use the commercial item of the cyclic polyolefin resin film made as the base film 101 or the thermoplastic resin film whose tensile elasticity modulus in 80 degreeC for forming this is less than 140 Mpa.

The base film 101 may be composed of one kind of cyclic polyolefin-based resin, may be composed of a mixture of two or more kinds of cyclic polyolefin-based resins, or may be composed of two or more kinds of cyclic polyolefin-based resins. You may be comprised from the copolymer.

The polyester-based resin is a resin having an ester bond, and is generally made of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. As the polyhydric alcohol, a divalent diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate and the like. It is done.

The base film 101 may be composed of one kind of polyester resin, may be composed of a mixture of two or more polyester resins, or a copolymer of two or more polyester resins. You may be comprised from.

Any appropriate (meth) acrylic resin can be adopted as the (meth) acrylic resin. Specific examples of the (meth) acrylic resin include, for example, poly (meth) acrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester Copolymer, methyl methacrylate-acrylic ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, Methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, C _1-6 alkyl poly (meth) acrylate such as poly (meth) acrylate is used, more preferably methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight). %) Is used.

The base film 101 may be composed of one kind of (meth) acrylic resin, may be composed of a mixture of two or more kinds of (meth) acrylic resins, or may be composed of two or more kinds of ( You may be comprised from the copolymer of the meth) acrylic-type resin.

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. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferable. Many products of cellulose triacetate are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available cellulose triacetate are “Fujitac TD80” (manufactured by Fuji Film Co., Ltd.), “Fujitac TD80UF” (manufactured by 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.

The base film 101 may be composed of one kind of cellulose ester resin, may be composed of a mixture of two or more kinds of cellulose ester resins, or may be composed of two or more kinds of cellulose ester resins. You may be comprised from the copolymer.

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, flame retardancy, and transparency. The polycarbonate-based resin constituting the base film 101 may be a resin called a modified polycarbonate in which the polymer skeleton is modified in order to lower the photoelastic coefficient, a copolymer polycarbonate having improved wavelength dependency, or the like.

Polycarbonate resin is available in various products. Examples of commercially available polycarbonate-based resins are all “Panlite” (manufactured by Teijin Chemicals Ltd.), “Iupilon” (manufactured by Mitsubishi Engineering Plastics), “SD Polyca” (Sumitomo Dow). (Manufactured by Dow Chemical Co., Ltd.).

The base film 101 may be composed of one type of polycarbonate resin, may be composed of a mixture of two or more types of polycarbonate resins, or is a copolymer of two or more types of polycarbonate resins. You may be comprised from.

Among these, polypropylene resins are preferably used from the viewpoints of stretchability and heat resistance.

Arbitrary appropriate additives may be added to the base film 101 in addition to the above thermoplastic resin. 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 in the base film 101 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. . When the content of the thermoplastic resin in the base film 101 is less than 50% by weight, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited.

The melting point of the thermoplastic resin constituting the base film 101 is preferably 110 ° C. or higher, and more preferably 130 ° C. or higher. When the melting point of the thermoplastic resin is less than 110 ° C., the base film 101 is easily melted in the stretching step S30 described later, and the stretching temperature cannot be sufficiently increased, making stretching more than 5 times difficult. is there. The melting point of the thermoplastic resin is a value measured at a temperature increase rate of 10 ° C./mim based on ISO3146.

The thickness of the substrate film 101 can be determined as appropriate, but generally it is preferably 1 to 500 μm, more preferably 1 to 300 μm, further preferably 5 to 200 μm, from the viewpoint of workability such as strength and handleability. Most preferred is 150 μm.

[2] Polyvinyl alcohol-based resin layer The polyvinyl alcohol-based resin layer 102 is a layer formed by applying a coating liquid containing a polyvinyl alcohol-based resin to the base film 101 and then drying the coating liquid. This is the layer that becomes the polarizer layer 302 through S30 and the dyeing step S40. According to such a forming method by coating, the thickness of the polyvinyl alcohol-based resin layer and thus the polarizer layer can be reduced, which is advantageous for thinning the polarizing laminated film and the polarizing plate. Moreover, since the base film 101 excellent in heat resistance having a tensile elastic modulus at 80 ° C. of 140 MPa or more is used, defects such as wrinkles or folds during drying of the coating layer and drying of the coating layer associated therewith are obtained. Problems such as defects can be effectively suppressed.

As described above, the polyvinyl alcohol-based resin layer 102 may be formed only on one surface of the base film 101 or on both surfaces. Since it is possible to obtain two polarizing plates from one polarizing laminated film while suppressing curling of the polarizing laminated film and the film that may occur during the production of the polarizing plate when formed on both sides, the production efficiency of the polarizing plate This is also advantageous.

The thickness of the polyvinyl alcohol-based resin layer 102 in the laminated film 100 is preferably 3 to 30 μm, and more preferably 5 to 20 μm. If it is the polyvinyl alcohol-type resin layer 102 which has the thickness in this range, the dyeing | staining property of a dichroic pigment | dye is excellent through the extending | stretching process S30 and dyeing | staining process S40 mentioned later, it is excellent in a polarizing characteristic, and thickness is small enough The polarizer layer 302 can be obtained. When the thickness of the polyvinyl alcohol-based resin layer 102 exceeds 30 μm, the thickness 302 of the polarizer layer may exceed 10 μm. Moreover, when the thickness of the polyvinyl alcohol-based resin layer 102 is less than 3 μm, the film becomes too thin after stretching and the dyeability tends to deteriorate.

<Manufacturing method of laminated film and polarizing laminated film>
FIG. 4 is a flowchart showing a preferred embodiment of a method for producing a laminated film, a polarizing laminated film and a polarizing plate according to the present invention. The manufacturing method of the laminated film of this embodiment includes the following steps:
A base film preparation step S10 for preparing a base film made of a thermoplastic resin film having a tensile elastic modulus at 80 ° C. of 140 MPa or more,
Resin layer forming step S20 to obtain a laminated film by forming a polyvinyl alcohol-based resin layer by applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film, and then drying;
Are included in this order.

Moreover, the manufacturing method of the light-polarizing laminated film of this embodiment includes the following steps:
A base film preparation step S10 for preparing a base film made of a thermoplastic resin film having a tensile elastic modulus at 80 ° C. of 140 MPa or more,
Resin layer forming step S20 to obtain a laminated film by forming a polyvinyl alcohol-based resin layer by applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film, and then drying;
Stretching step S30 to obtain a stretched film by uniaxially stretching the resulting laminated film,
Dyeing step S40 to obtain a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer,
Are included in this order.

As will be described later, in the present embodiment, the polarizing plate is bonded to a protective film on the polarizer layer of the polarizing laminated film obtained by carrying out the dyeing step S40 (bonding step S50). ), And then the substrate film can be peeled off from the bonded film (peeling step S60).

Hereinafter, each step of S10 to S40 will be described in more detail.
[1] Base film preparation step S10
This step is a step of preparing a base film 101 made of a thermoplastic resin film having a tensile elastic modulus at 80 ° C. of 140 MPa or more (preferably 150 MPa or more, more preferably 155 MPa or more). As mentioned above, as an effective method for obtaining such a base film 101,
1) A method of heat-treating the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the subsequent resin layer forming step S20; and 2) The surface layer 101a of the surface on which at least the polyvinyl alcohol-based resin layer is formed in the thermoplastic resin film. A method for increasing the crystallinity to 58% or more (preferably 59% or more, more preferably 60% or more);
Can be mentioned.

As mentioned above, the method 1) can be adopted regardless of whether the thermoplastic resin constituting the thermoplastic resin film is crystalline or amorphous. The method 2) can be employed when at least the surface layer of the thermoplastic resin film is composed of a crystalline thermoplastic resin. Regarding the method 2), the method for increasing the crystallinity of the surface layer 101a to 58% or more includes at least a crystalline thermoplastic resin in addition to the method of heat-treating the thermoplastic resin film as in the method 1). The method of making a surface layer contain a nucleating agent can be mentioned.

Thus, base film preparatory process S10 heat-processes a thermoplastic resin film at the temperature more than the drying temperature in subsequent resin layer formation process S20 (henceforth "heat processing process S10"). -A "), or at least the surface layer 101a (the surface layer on which the polyvinyl alcohol-based resin layer 102 is formed in the subsequent resin layer forming step S20) is a crystalline thermoplastic resin containing a nucleating agent. It can comprise a step of preparing a base film 101 made of a thermoplastic resin film (hereinafter referred to as “nucleating agent addition step S10-b”). The base film preparation step S10 may include both the heat treatment step S10-a and the nucleating agent addition step S10-b.

In the heat treatment step S10-a, the thermoplastic resin film is heated at a temperature equal to or higher than the drying temperature in the subsequent resin layer forming step S20 so that the obtained base film 101 has a tensile elastic modulus at 80 ° C. of 140 MPa or more. To process. As the thermoplastic resin constituting the thermoplastic resin film, the crystalline or amorphous thermoplastic resin exemplified above can be used. When the crystallinity of the surface layer 101a is increased to 58% or higher, and thereby the tensile elastic modulus is set to 140 MPa or higher, at least the surface layer of the thermoplastic resin film is made of a crystalline thermoplastic resin.

Specific examples of the crystalline thermoplastic resin include, for example, a chain polyolefin resin, a polyester resin, a crystalline cellulose ester resin, a polyvinyl alcohol resin, a polystyrene resin, a polyamide resin, a polyimide resin, and a mixture thereof. And copolymers. More specific examples of the crystalline chain polyolefin resin include, for example, a homopolymer composed of ethylene, propylene or an α-olefin having 4 to 20 carbon atoms, and a copolymer composed of two or more of these monomers. Etc. Specific examples of the crystalline polyester-based resin include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and the like.

By heat-treating (annealing) the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the resin layer forming step S20, crystallization of the thermoplastic resin film proceeds and the heat resistance of the obtained base film 101 is improved. . Thereby, in the next resin layer forming step S20, when heating to dry and remove the solvent in the layer (coating layer) made of the coating liquid, defects such as wrinkles and folds are formed in the base film 101. It is possible to effectively suppress the occurrence of the occurrence of the occurrence of a dry failure due to the coating liquid remaining in the defective portion. In addition, the drying temperature in resin layer formation process S20 here means the maximum temperature at the time of drying.

When the heat treatment step S10-a itself is not included, or when the heat treatment step S10-a does not include the step of heat treating the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the resin layer forming step S20, The film 101 does not have sufficient heat resistance, and the above problems may occur, and productivity and yield may be reduced.

The heat treatment temperature in the heat treatment step S10-a depends on the material of the thermoplastic resin film and the drying temperature in the resin layer forming step S20. For example, when the solvent of the coating liquid contains water, the heat treatment temperature is dried to prevent poor drying. Since the temperature is preferably 80 ° C. or higher, the heat treatment temperature is preferably 80 ° C. or higher, and more preferably 90 ° C. or higher. Although depending on the material of the thermoplastic resin film, crystallization of the base film 101 can be favorably progressed if the heat treatment temperature is 80 ° C. or higher, preferably 90 ° C. or higher. The heat treatment temperature is usually adjusted to be lower than the phase transition temperature (melting point or glass transition temperature) of the thermoplastic resin film.

The heat treatment time in the heat treatment step S10-a is preferably 3 seconds to 5 minutes, and preferably 5 seconds to 3 minutes. By setting the heat treatment time to 3 seconds or more, a significant effect of improving the heat resistance of the base film 101 can be obtained. The heat treatment time exceeding 5 minutes is disadvantageous in terms of productivity.

The heat treatment step S10-a may consist of a single heat treatment step or may be a combination of multi-step heat treatment steps. In the former case, the heat treatment step is a step of heat-treating the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the resin layer forming step S20. In the latter case, one or more of the multi-stage heat treatment steps is a step of heat-treating the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the resin layer forming step S20. The heat treatment at each stage constituting the heat treatment step S10-a includes, for example, a zone heating method in which the heat treatment is performed by passing through a drying furnace (oven), a method in which the heat treatment is performed by contact with a heat roll, and a thermoplastic resin film. It can be selected from a method of heating and drying while stretching in a direction perpendicular to the conveying direction. For example, a plurality of heat treatment methods may be combined such that the first stage is heated by a hot roll and the second stage is zone heating.

When the heat treatment step S10-a is a combination of multi-step heat treatment steps, the heat treatment step S10-a is a step of heat-treating the thermoplastic resin film at a temperature lower than the drying temperature in the resin layer forming step S20. Can be included.

In the case where the heat treatment step S10-a is a combination of multi-step heat treatment steps, the heat treatment time in the entire heat treatment step S10-a may be 3 seconds to 5 minutes for the same reason as described above. Preferably, it is 5 seconds to 3 minutes.

In the case where at least the surface layer of the thermoplastic resin film is composed of a crystalline thermoplastic resin, the maximum heat treatment temperature and the heat treatment time in the heat treatment step S10-a do not excessively increase the crystallinity of the base film 101. Thus, it adjusts suitably according to the material etc. of a thermoplastic resin film. If the maximum heat treatment temperature is excessively increased or the heat treatment time is excessively increased, the crystallinity of the base film 101 becomes excessively high and the stretchability tends to be impaired.

Further, in this step, when at least the surface layer of the thermoplastic resin film is composed of a crystalline thermoplastic resin, in order to increase the crystallinity of at least the surface layer 101a in the base film 101 more effectively, heating is performed. You may perform an extending | stretching process at the time of a process. In particular, when the thermoplastic resin film is made of a resin that easily undergoes oriented crystallization, such as a polyester-based resin such as polyethylene terephthalate, the stretching treatment is effective in improving the crystallinity.

The stretching method may be any method such as longitudinal stretching, lateral stretching, and oblique stretching, and a plurality of stretching methods may be combined. Especially, since the base film 101 of a larger area is obtained, it is preferable to include horizontal stretching. The stretching ratio (when combining a plurality of stretching methods, the total stretching ratio) is preferably 1.01 to 5 times, more preferably 1.01 to 3 times. If the draw ratio is 5 times or less, the crystallinity is not excessively increased, and the stretchability of the laminated film 100 in the stretching step S30 can be sufficiently secured. When the draw ratio is too high, the base film 101 becomes brittle and the drawability is lowered.

As will be described later, in order to improve the adhesion between the base film 101 and the polyvinyl alcohol-based resin layer 102, the base film 101 is formed between the base film preparation step S10 and the resin layer formation step S20 described later. A primer layer forming step for forming the primer layer can be provided. The primer layer can be formed by applying a primer layer forming coating solution to the substrate film 101 and then drying it. Therefore, when this primer layer forming step is carried out, defects such as wrinkles and folds are generated in the base film 101 during drying of the coating layer in the step, or the coating liquid is present in the defective portion. In order to effectively suppress the accumulation and poor drying, the heat treatment step S10-a may include a step of heat treating the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the primer layer forming step. preferable.

The step of heat-treating the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the primer layer forming step is the same step as the step of heat-treating the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the resin layer forming step S20 described above. It may be a different heat treatment step included in the heat treatment step S10-a.

Regarding the heat treatment temperature and the heat treatment time in the step of heat-treating the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the primer layer forming step, heat-treat the thermoplastic resin film at a temperature equal to or higher than the drying temperature in the resin layer forming step S20. The above description of the process to do is cited.

On the other hand, when the base film preparation step S10 includes the nucleating agent addition step S10-b, at least the surface layer 101a on the surface on which the polyvinyl alcohol-based resin layer 102 is formed in the resin layer forming step S20 contains the nucleating agent. A thermoplastic resin film composed of a crystalline thermoplastic resin is produced and used as a base film 101. By including a nucleating agent, the crystallinity of at least the surface layer 101a can be 58% or more.

The kind of the thermoplastic resin constituting the thermoplastic resin film is not particularly limited as long as at least the surface layer 101a is made of a crystalline thermoplastic resin, and even if the entire thermoplastic resin film is made of a crystalline thermoplastic resin. In the case where the thermoplastic resin film has a multilayer structure, only the layer including the surface layer 101a may be composed of a crystalline thermoplastic resin, and the other layers may be composed of an amorphous thermoplastic resin. Specific examples of the crystalline thermoplastic resin are as described above.

The base film 101, which is a thermoplastic resin film containing a nucleating agent in the surface layer 101a, is added to and kneaded with the nucleating agent in the thermoplastic resin raw material constituting the base film 101, and the nucleating agent-containing thermoplastic resin raw material is used. It can be obtained by forming a film by a known method.

The nucleating agent is a substance that becomes the nucleus of the crystal. Since many nuclei are formed by the addition of the nucleating agent, the crystallinity of the crystalline thermoplastic resin portion containing the nucleating agent is increased and the heat resistance is improved when the thermoplastic resin material is formed. Thereby, in the next resin layer forming step S20, when heating to dry and remove the solvent in the layer (coating layer) made of the coating liquid, defects such as wrinkles and folds are formed in the base film 101. It is possible to effectively suppress the occurrence of the occurrence of the occurrence of a dry failure due to the coating liquid remaining in the defective portion.

As the nucleating agent, either an organic nucleating agent or an inorganic nucleating agent may be used.
Specific examples of the organic nucleating agent include, for example, carboxylic acid, dicarboxylic acid and salts or anhydrides thereof; salt or ester of aromatic sulfonic acid; aromatic phosphinic acid, aromatic phosphonic acid, aromatic carboxylic acid or aluminum thereof Salt; aromatic metal phosphate; alkyl alcohol having 8 to 30 carbon atoms; condensate of polyhydric alcohol and aldehyde; alkylamine; chain polyolefin resin.

Among the above, it is preferable to use a chain polyolefin-based resin. From the viewpoint of physical strength of the obtained base film 101 and suppression of bleeding of the nucleating agent, a single weight composed of an aliphatic monoolefin having 2 to 6 carbon atoms. It is more preferable to use a polymer or copolymer having a number average molecular weight of about 10,000 to 200,000 (preferably 20,000 to 150,000) and a high molecular weight. Specific examples of such a homopolymer or copolymer include, for example, homopolypropylene resin, low density polyethylene resin, high density polyethylene resin, copolymer resin of ethylene and α-olefin having 4 to 6 carbon atoms, ethylene- And propylene copolymer resins.

Specific examples of the inorganic nucleating agent include, for example, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal oxides such as sodium oxide; lithium carbonate, sodium carbonate, potassium carbonate, and hydrogen carbonate. Alkali metal carbonates such as sodium and potassium hydrogen carbonate; alkaline earth metal hydroxides such as calcium hydroxide, magnesium hydroxide and barium hydroxide; alkaline earth metal oxides such as calcium carbonate and calcium oxide.

Of course, it is also possible to use a nucleating agent other than those exemplified above. A nucleating agent may be used individually by 1 type, and may use 2 or more types together.

The content of the nucleating agent is such that the crystallinity of the surface layer 101a can be 58%, and the tensile modulus at 80 ° C. of the base film 101 can be increased to 140 MPa or more accordingly. is there. When the content of the nucleating agent is too small, it is not possible to obtain the base film 101 exhibiting a desired tensile elastic modulus. On the other hand, when the content is too large, the stretchability of the laminated film 100 is reduced, Agent bleeding may occur. Therefore, although depending on the material of the thermoplastic resin film, the nucleating agent is preferably contained in a proportion of 0.1 to 10% by weight of the thermoplastic resin, and contained in a proportion of 0.3 to 5% by weight. It is more preferable.

As described above, the base film preparation step S10 can include both the heat treatment step S10-a and the nucleating agent addition step S10-b. A thermoplastic resin film containing a nucleating agent is produced on the surface layer, and further subjected to heat treatment at a predetermined temperature, thereby improving the crystallinity of the base film 101 and thus the heat resistance more efficiently. obtain.

[2] Resin layer forming step S20
This step is a step of obtaining the laminated film 100 by forming the polyvinyl alcohol resin layer 102 on at least one surface of the base film 101. As described above, the polyvinyl alcohol-based resin layer 102 can be formed by applying a coating liquid containing a polyvinyl alcohol-based resin to one or both sides of the base film 101 and drying the coating layer. .

The coating liquid is preferably a polyvinyl alcohol resin solution obtained by dissolving a polyvinyl alcohol resin powder in a good solvent (for example, water). Examples of the polyvinyl alcohol resin include polyvinyl alcohol resins and derivatives thereof. 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 resins, it is preferable to use a polyvinyl alcohol resin.

The average degree of polymerization of the polyvinyl alcohol resin is preferably 100 to 10,000, and more preferably 1000 to 10,000. In particular, 1500 to 8000 is more preferable, and 2000 to 5000 is most preferable. The average degree of polymerization is a numerical value obtained by a method defined by JIS K 6726 (1994). If the average degree of polymerization is less than 100, it is difficult to obtain preferable optical characteristics. If it exceeds 10,000, the solubility in water deteriorates and it becomes difficult to form a resin layer.

The polyvinyl alcohol resin is preferably a saponified product. The range of the degree of saponification is preferably 80.0 to 100.0 mol%, more preferably 90.0 to 99.5 mol%, and 93.0 to 99.5 mol%. Is more preferable. For example, a polyvinyl alcohol resin having a saponification degree of 98.0 to 99.5 mol% can be used. When the degree of saponification is less than 80.0 mol%, it is difficult to obtain preferable optical characteristics. The degree of saponification 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. :
Saponification degree (mol%) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100
It is a numerical value defined by. It can be determined by the method defined in JIS K 6726 (1994).

Examples of commercially available polyvinyl alcohol resins that can be suitably used include “PVA124” (degree of saponification: 98.0 to 99.0 mol%) and “PVA117” (degree of saponification: 98.95) manufactured by Kuraray Co., Ltd. 0-99.0 mol%), “PVA117H” (degree of saponification: 99.5 mol% or more); “AH-26” (degree of saponification: 97.0-98. 8 mol%), “AH-22” (degree of saponification: 97.5-98.5 mol%), “NH-18” (degree of saponification: 98.0-99.0 mol%), “N— 300 "(degree of saponification: 98.0 to 99.0 mol%);" JC-33 "(degree of saponification: 99.0 mol% or more) of Nippon Vinegar Poval Co., Ltd.," JP-45 " (Degree of saponification: 86.5 to 89.5 mol%), “JF-17” (degree of saponification: 98.0 to 99.0 mol%), “JF -17L "(degree of saponification: 98.0 to 99.0 mol%) and" JF-20 "(degree of saponification: 98.0 to 99.0 mol%).

The coating liquid may contain additives such as a plasticizer and a surfactant as necessary. As the plasticizer, a polyol or a condensate 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 preferably 20% by weight or less of the polyvinyl alcohol resin.

The coating liquid is applied to the substrate film 101 by roll coating methods such as wire bar coating, reverse coating, and gravure coating; die coating method; comma coating method; lip coating method; spin coating method; screen coating method; It can be appropriately selected from known methods such as a fountain coating method, a dipping method, and a spray method.

The drying temperature and drying time of the coating layer are set according to the type of solvent contained in the coating solution. The drying temperature is, for example, 50 to 200 ° C., preferably 60 to 150 ° C. When the solvent contains water, the drying temperature is preferably 80 ° C. or higher. The drying time is, for example, 2 to 20 minutes.

In order to improve the adhesion with the polyvinyl alcohol resin layer 102, at least the surface of the base film 101 on the side where the polyvinyl alcohol resin layer 102 is formed may be subjected to corona treatment, plasma treatment, flame treatment, or the like. Good.

[3] Primer layer forming step As described above, in order to improve the adhesion between the base film 101 and the polyvinyl alcohol-based resin layer 102, between the base film preparing step S10 and the resin layer forming step S20, You may provide the process of forming a primer layer in the surface in which the said coating liquid is coated in the base film 101. FIG. The primer layer can be formed by applying a primer layer forming coating solution to the substrate film 101 and then drying it.

The primer layer forming coating solution is not particularly limited as long as it includes a material that exhibits a certain degree of strong adhesion to both the base film 101 and the polyvinyl alcohol-based resin layer 102. The primer layer-forming coating solution usually contains a resin component that imparts such adhesion and a solvent. As the resin component, a thermoplastic resin excellent in transparency, thermal stability, stretchability, and the like is preferably used, and examples thereof include (meth) acrylic resins and polyvinyl alcohol resins. Among these, polyvinyl alcohol resins that give good adhesion are preferably used.

Examples of the polyvinyl alcohol resin include polyvinyl alcohol resins and derivatives thereof. 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 resins, it is preferable to use a polyvinyl alcohol resin.

As the solvent, a general organic solvent or an aqueous solvent capable of dissolving the resin component is usually used. Examples of solvents include 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; methylene chloride, trichloroethylene and chloroform Chlorinated hydrocarbons such as ethanol; alcohols such as ethanol, 1-propanol, 2-propanol and 1-butanol. However, if the primer layer is formed using a primer layer forming coating solution containing an organic solvent, the substrate film 101 may be dissolved. Therefore, the solvent should be selected in consideration of the solubility of the film. Is preferred. Considering the influence on the environment, it is preferable to form the primer layer from a coating solution containing water as a solvent.

In order to increase the strength of the primer layer, a crosslinking agent may be added to the primer layer forming coating solution. A suitable crosslinking agent is appropriately selected from known ones such as organic and inorganic based on the type of thermoplastic resin used. Examples of the crosslinking agent include epoxy-based, isocyanate-based, dialdehyde-based, and metal-based crosslinking agents. As the epoxy-based crosslinking agent, either one-component curable type or two-component curable type can be used. Ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexanediol diester Epoxies such as glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diglycidyl amine and the like can be mentioned.

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 a block thing or a phenol block thing, are mentioned.

Examples of the dialdehyde-based cross-linking 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. 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 salts, oxides and hydroxides of metals having a valence higher than the valence.

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.

Suitable examples of the organometallic compound include an organotitanium compound, an organozirconium compound, an organoaluminum compound, and an organosilicon compound. An organometallic compound may be used individually by 1 type, and may use 2 or more types together.

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

Examples of the organic zirconium compound include zirconium normal propylate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium acetylacetonate bisethylacetoacetate and the like.

Examples of the organic aluminum compound include aluminum acetylacetonate and aluminum organic acid chelate. As an organosilicon compound, the compound which has the ligand illustrated by the organic titanium compound and organic zirconium compound which were mentioned above is mentioned, for example.

In addition to the above low-molecular crosslinking agents, polymer 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 resin is used as the resin component of the primer layer, a polyamide epoxy resin, a methylolated melamine resin, a dialdehyde crosslinking agent, a metal chelate compound crosslinking agent and the like are particularly preferable.

The ratio of the resin component to the crosslinking agent in the primer layer forming coating solution is within the range of about 0.1 to 100 parts by weight of the crosslinking agent with respect to 100 parts by weight of the resin component. And the like, and it is preferable to select from the range of about 0.1 to 50 parts by weight. The primer layer forming coating solution 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, and more preferably 0.1 to 0.4 μm. When the thickness is less than 0.05 μm, the effect of improving the adhesion between the base film 101 and the polyvinyl alcohol-based resin layer 102 is small, and when the thickness is more than 1 μm, it is disadvantageous for thinning the polarizing laminated film and the polarizing plate.

The method of applying the primer layer forming coating solution to the base film 101 can be the same as the coating solution for forming the polyvinyl alcohol-based resin layer. The primer layer is applied to the surface (one surface or both surfaces of the base film 101) to which the coating liquid for forming the polyvinyl alcohol-based resin layer is applied. The drying temperature and drying time of the coating layer comprising the primer layer forming coating solution are set according to the type of solvent contained in the coating solution. The drying temperature is, for example, 50 to 200 ° C., preferably 60 to 150 ° C. When the solvent contains water, the drying temperature is preferably 80 ° C. or higher. The drying time is, for example, 30 seconds to 20 minutes.

[4] Stretching step S30
This step is a step of obtaining the stretched film 200 by uniaxially stretching the laminated film 100 composed of the base film 101 and the polyvinyl alcohol-based resin layer 102 (see FIG. 2). The stretching ratio of the laminated film 100 can be appropriately selected depending on the desired polarization characteristics, but is preferably more than 5 times and not more than 17 times, more preferably more than 5 times the original length of the laminated film 100. 8 times or less. When the draw ratio is 5 times or less, the polyvinyl alcohol-based resin layer 102 is not sufficiently oriented, and the degree of polarization of the polarizer layer 302 obtained through the dyeing step S40 may not be sufficiently high. On the other hand, when the draw ratio exceeds 17 times, the film is likely to be broken during stretching, and the thickness of the stretched film 200 becomes unnecessarily thin, and the workability and handleability in subsequent processes may be reduced.

The stretching process is not limited to one-stage stretching, and can be performed in multiple stages. In this case, all the multistage stretching processes may be performed continuously before the dyeing process S40, or the second and subsequent stretching processes may be performed simultaneously with the dyeing process and / or the crosslinking process in the dyeing process S40. Good. Thus, when performing a extending | stretching process in multistage, it is preferable to perform an extending | stretching process so that it may become a draw ratio exceeding 5 times combining all the stages of an extending | stretching process.

The stretching treatment may be longitudinal stretching that extends in the film longitudinal direction (film transport direction), and may be lateral stretching or oblique stretching that extends in the film width direction. Examples of the longitudinal stretching method include inter-roll stretching and compression stretching, and examples of the lateral stretching method include a tenter method. As the stretching treatment, either a wet stretching method or a dry stretching method can be adopted. However, it is preferable to use the dry stretching method because the stretching temperature can be selected from a wide range.

The stretching temperature is set to be equal to or higher than the temperature at which the polyvinyl alcohol-based resin layer 102 and the entire base film 101 can be stretched, and preferably the phase transition temperature (melting point or glass transition temperature) of the base film 101. It is in the range of −30 ° C. to + 30 ° C., more preferably in the range of −30 ° C. to + 5 ° C., and still more preferably in the range of −25 ° C. to + 0 ° C. When the base film 101 consists of a plurality of resin layers, the phase transition temperature means the highest phase transition temperature among melting points indicated by the plurality of resin layers.

When the stretching temperature is lower than the phase transition temperature of −30 ° C., it is difficult to achieve high-magnification stretching of more than 5 times. When the stretching temperature exceeds + 30 ° C. of the phase transition temperature, the fluidity of the base film 101 is too high and stretching tends to be difficult. Since it is easier to achieve a high draw ratio of more than 5 times, the drawing temperature is within the above range, and more preferably 120 ° C. or higher. This is because when the stretching temperature is 120 ° C. or higher, there is no difficulty in the stretching treatment even at a high stretching ratio of more than 5 times. The temperature adjustment of the stretching process is usually performed by adjusting the temperature of the heating furnace.

[5] Dyeing step S40
This step is a step in which the polyvinyl alcohol resin layer 202 of the stretched film 200 is dyed with a dichroic dye and adsorbed and oriented to form the polarizer layer 302. Through this step, a polarizing laminated film 300 in which the polarizer layer 302 is laminated on one side or both sides of the base film 301 is obtained (see FIG. 3).

Examples of dichroic pigments include iodine and organic dyes. Specific examples of organic dyes include, for example, 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 Includes Blue, Direct First Orange S, First Black, etc. A dichroic dye may be used individually by 1 type, and may use 2 or more types together.

The dyeing step can be performed by immersing the entire stretched film 200 in a solution (dye solution) containing a dichroic dye. As the dyeing solution, a solution in which the dichroic dye is dissolved in a solvent can be used. As the 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 further preferably 0.025 to 5% by weight.

When iodine is used as the dichroic dye, it is preferable to further add an iodide to the dyeing solution containing iodine because the dyeing efficiency can be further improved. Examples of 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 concentration of iodide in the dyeing solution is preferably 0.01 to 20% by weight. 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. Preferably, it is in the range of 1: 7 to 1:70.

The immersion time of the stretched film 200 in the dyeing solution is usually in the range of 15 seconds to 15 minutes, preferably 20 seconds to 6 minutes. The temperature of the dyeing solution is preferably in the range of 10 to 60 ° C., more preferably in the range of 20 to 40 ° C.

In addition, although it is also possible to perform dyeing process S40 before extending | stretching process S30 simultaneously, the extending | stretching process in extending process S30 so that the dichroic dye adsorb | sucked to the polyvinyl alcohol-type resin layer can be favorably oriented. It is preferable to carry out the dyeing step S40 after carrying out at least part of the above. As an embodiment in this case, 1) an embodiment in which the dyeing step S40 is performed without the drawing treatment after the drawing treatment is performed at the target magnification, and 2) after the drawing treatment is performed at a lower magnification than the target, the dyeing is performed. During the dyeing process in step S40 (when the dyeing process S40 includes a cross-linking process), the stretching process is performed so that the total magnification becomes the target magnification. 3) A magnification lower than the target After the stretching process is performed, the total magnification is not extended to the target magnification during the dyeing process in the dyeing process S40 (when the dyeing process S40 includes a crosslinking process, the dyeing process and / or the crosslinking process). Examples include an embodiment in which the treatment is performed and then the stretching treatment is performed so that the total magnification becomes the target magnification.

The dyeing step S40 can include a cross-linking treatment step performed subsequent to the dyeing treatment. The crosslinking treatment can be performed by immersing the dyed film in a solution containing a crosslinking agent (crosslinking solution). As the crosslinking agent, conventionally known substances can be used, and examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. A crosslinking agent may be used individually by 1 type, and may use 2 or more types together.

Specifically, the crosslinking solution can be a solution in which a crosslinking agent is dissolved in a solvent. As the solvent, for example, water can be used, but an organic solvent compatible with water may be further included. The concentration of the crosslinking agent in the crosslinking solution is preferably in the range of 1 to 20% by weight, more preferably in the range of 5 to 15% by weight.

The crosslinking solution can contain iodide. By adding iodide, the polarization characteristics in the plane of the polarizer layer 302 can be made more uniform. Examples of 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 concentration of iodide in the cross-linking solution is preferably 0.05 to 15% by weight, and more preferably 0.5 to 8% by weight.

The immersion time of the dyed film in the crosslinking solution is usually 15 seconds to 20 minutes, preferably 30 seconds to 15 minutes. The temperature of the crosslinking solution is preferably in the range of 10 to 80 ° C.

The crosslinking treatment can be performed simultaneously with the dyeing treatment by blending a crosslinking agent in the dyeing solution. Moreover, you may perform a bridge | crosslinking process and a part of extending process simultaneously. The specific mode for carrying out the stretching treatment during the crosslinking treatment is as described above.

It is preferable to perform a washing | cleaning process and a drying process after dyeing process S40 and before the bonding process S50 mentioned later. The washing process usually includes a water washing process. The water washing treatment can be performed by immersing the film after the dyeing treatment or after the crosslinking treatment 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 in water is usually 2 to 300 seconds, preferably 3 to 240 seconds.

The washing step may be a combination of a water washing step and a washing step with an iodide solution. In addition to water, liquids such as methanol, ethanol, isopropyl alcohol, butanol, and propanol can be appropriately contained in the cleaning liquid used in the water cleaning step and / or the cleaning treatment with the iodide solution.

Any appropriate method such as natural drying, blow drying, or heat drying can be adopted as the drying step performed after the washing step. For example, in the case of heat drying, the drying temperature is usually 20 to 95 ° C., and the drying time is usually about 1 to 15 minutes. The polarizing laminated film 300 obtained as described above can be used as a polarizing element as it is, and is also useful as an intermediate for producing a polarizing plate comprising a polarizer layer 302 and a protective film.

<Production method of polarizing plate>
The manufacturing method of the polarizing plate of this invention is the process of preparing the above-mentioned polarizing laminated film 300, bonding process S50 which bonds a protective film on the polarizer layer 302 of the polarizing laminated film 300, and obtains a bonding film S50. The peeling process S60 which peels and removes the base film 301 from the bonding film is included in this order.

[6] Pasting step S50
This step is a step of obtaining a bonding film by bonding a protective film on the polarizer layer 302 of the polarizing laminated film 300. The protective film can be bonded to the polarizer layer 302 using an adhesive or a pressure-sensitive adhesive. When the polarizing laminated film 300 has the polarizer layers 302 on both surfaces of the base film 301, the protective films are usually bonded on the polarizer layers 302 on both surfaces. In this case, these protective films may be the same type of protective film or different types of protective films.

(Protective film)
The protective film is, for example, a polyolefin resin such as a chain polyolefin resin (such as a polypropylene resin) or a cyclic polyolefin resin (such as a norbornene resin); a cellulose ester resin such as cellulose triacetate or cellulose diacetate; a polyethylene terephthalate, It can be a film made of a polyester resin such as polyethylene naphthalate or polybutylene terephthalate; a polycarbonate resin; a (meth) acrylic resin; or a mixture or copolymer thereof. Examples of commercially available products such as cyclic polyolefin resins and films thereof, and cellulose triacetate are as described above.

The protective film can also be a protective film having an optical function such as a retardation film and a brightness enhancement film. For example, a retardation film provided with an arbitrary retardation value by stretching a resin film made of the above material (uniaxial stretching or biaxial stretching, etc.) or forming a liquid crystal layer or the like on the film. can do.

An optical layer such as a hard coat layer, an antiglare layer, or an antireflection layer can be formed on the surface of the protective film opposite to the polarizer layer 302. 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 optical layer may be formed in advance on the protective film prior to the bonding step S50, or may be formed after the bonding step S50 or after the peeling step S60 described later.

In order to improve the adhesiveness with the polarizer layer 302 via an adhesive or a pressure sensitive adhesive on the surface of the protective film on the polarizer layer 302 side, plasma treatment, corona treatment, ultraviolet irradiation treatment, frame (flame) treatment, Surface treatment (easily bonding treatment) such as saponification treatment can be performed, and among them, corona treatment and saponification treatment are preferable. For example, when the protective film is made of a cyclic polyolefin-based resin, plasma treatment or corona treatment is usually performed. Moreover, when it consists of a cellulose ester-type resin, a saponification process is normally performed. Examples of the saponification treatment include a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

The thickness of the protective film is preferably thin, but if it is too thin, the strength decreases and the processability is poor. On the other hand, when too thick, problems, such as transparency falling and the curing time required after bonding, will arise. Therefore, the thickness of the protective film is preferably 90 μm or less, more preferably 5 to 60 μm. Further, from the viewpoint of thinning the polarizing plate, the total thickness of the polarizer layer 302 and the protective film is preferably 100 μm or less, more preferably 90 μm or less, and further preferably 80 μm or less.

(adhesive)
As the adhesive, a water-based adhesive or a photocurable adhesive can be used. Examples of the water-based adhesive include an adhesive made of a polyvinyl alcohol-based resin aqueous solution, an aqueous two-component urethane emulsion adhesive, and the like. In particular, when a cellulose ester-based resin film that has been surface-treated (hydrophilized) by a saponification treatment or the like is used as a protective film, it is preferable to use a water-based adhesive comprising a polyvinyl alcohol-based resin aqueous solution.

Polyvinyl alcohol resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. A polyvinyl alcohol copolymer obtained by saponifying a polymer or a modified polyvinyl alcohol polymer obtained by partially modifying a hydroxyl group thereof can be used. The water-based adhesive can include additives such as polyvalent aldehydes, water-soluble epoxy compounds, melamine compounds, zirconia compounds, and zinc compounds. When an aqueous adhesive is used, the thickness of the adhesive layer obtained therefrom is usually 1 μm or less.

An aqueous adhesive is applied onto the polarizer layer 302 and / or the protective film of the polarizing laminated film 300, and these films are bonded via the adhesive layer, preferably using a bonding roll or the like. A pasting process is carried out by pressing and adhering. The coating method of the water-based adhesive (same for the photo-curable adhesive) is not particularly limited, and casting method, Meyer bar coating method, gravure coating method, comma coater method, doctor plate method, die coating method, dip coating method A conventionally known method such as a spraying method can be used.

When using a water-based adhesive, it is preferable to carry out a drying step for drying the film in order to remove water contained in the water-based adhesive after performing the above-mentioned bonding. Drying can be performed, for example, by introducing the film into a drying furnace. The drying temperature (drying furnace temperature) is preferably 30 to 90 ° C. When it is lower than 30 ° C., the protective film tends to be easily peeled off from the polarizer layer 302. On the other hand, if the drying temperature exceeds 90 ° C., the polarization performance may be deteriorated by heat. The drying time can be 10 to 1000 seconds, and from the viewpoint of productivity, it is preferably 60 to 750 seconds, and more preferably 150 to 600 seconds.

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

The photocurable adhesive refers to an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, for example, an adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photoreactive resin, and a binder. The thing containing resin and a photoreactive crosslinking agent can be mentioned. Examples of the polymerizable compound include photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable urethane monomer, and oligomers derived from the photopolymerizable monomer. As a photoinitiator, what contains the substance which generate | occur | produces active species, such as a neutral radical, an anion radical, and a cation radical by irradiation of active energy rays, such as an ultraviolet-ray, can be mentioned. As the photocurable adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photocurable epoxy monomer and a photocationic polymerization initiator can be preferably used.

When using a photocurable adhesive, after carrying out the above-mentioned bonding, a drying process is performed as necessary (such as when the photocurable adhesive contains a solvent), and then light is irradiated by activating active energy rays. A curing step for curing the curable adhesive is performed. 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 the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW / cm ^2. It is preferable to set to. When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when the irradiation intensity is 6000 mW / cm ² or less, the light emitted from the light source and the light generated by the curing of the photocurable adhesive There is little possibility of causing yellowing of the curable adhesive and deterioration of the polarizer layer 302.

The light irradiation time to the photocurable adhesive is also determined appropriately depending on the composition of the photocurable adhesive, and the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 10,000 mJ / cm ^2. It is preferable to set to. When the integrated light amount is 10 mJ / cm ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to advance the curing reaction more reliably, and when it is 10000 mJ / cm ² or less, the irradiation time is long. It does not become too much 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 to 2 μm, more preferably 0.01 to 1 μm.

(Adhesive)
The pressure-sensitive adhesive used for bonding the protective film is usually a composition in which an acrylic resin, styrene resin, 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. It consists of things. Furthermore, it can also be set as the adhesive layer which contains microparticles | fine-particles and shows light-scattering property.

The thickness of the pressure-sensitive adhesive layer can be 1 to 40 μm, but it is preferably applied thinly, as long as it does not impair the workability and durability characteristics, and specifically 3 to 25 μm. When the thickness is 3 to 25 μm, the thickness is favorable for suppressing the dimensional change of the polarizer layer 302 with good workability. 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. In the method of bonding a protective film to the polarizer layer 302 using an adhesive, after the adhesive layer is provided on the protective film surface, it may be bonded to the polarizer layer 302, or the surface of the polarizer layer 302 After providing the pressure-sensitive adhesive layer, a protective film may be bonded here.

The method for forming the pressure-sensitive adhesive layer is not particularly limited, and a pressure-sensitive adhesive solution containing each component including the above-described base polymer is applied to the surface of the protective film or the polarizer layer 302 and dried. After forming the pressure-sensitive adhesive layer, the protective film and the polarizer layer 302 may be bonded together, or after forming the pressure-sensitive adhesive layer on the separator, the pressure-sensitive adhesive layer is applied to the surface of the protective film or the polarizer layer 302. After the transfer, the protective film and the polarizer layer 302 may be bonded together. When the pressure-sensitive adhesive layer is formed on the protective film surface or the polarizer layer 302 surface, surface treatment, for example, corona treatment, is applied to one or both of the protective film surface or the polarizer layer 302 surface or the pressure-sensitive adhesive layer as necessary. Etc. may be applied.

[7] Peeling step S60
This process is a peeling removal process of the base film 301 from the bonding film obtained by bonding a protective film. Through this step, a polarizing plate in which a protective film is laminated on the polarizer layer 302 can be obtained. When the polarizing laminated film 300 has the polarizer layers 302 on both surfaces of the base film 301 and a protective film is bonded to both of the polarizer layers 302, two polarizing plates are obtained by the peeling step S60. Is obtained.

The method of peeling and removing the base film 301 is not particularly limited, and can be peeled by the same method as the separator (peeling film) peeling step performed with a normal pressure-sensitive adhesive polarizing plate. After the bonding step S50, the base film 301 may be peeled off immediately, or after the bonding step S50, it may be wound up in a roll shape and peeled off while being unwound in the subsequent steps.

The polarizing plate produced as described above can be used as an optical film in which other optical layers are laminated in practical use. Moreover, the protective film may have the function of such an optical layer. As another optical layer, a reflective polarizing film that transmits a certain kind of polarized light and reflects polarized light having the opposite properties; a film with an antiglare function having an uneven shape on the surface; a film with a surface antireflection function 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” (available from 3M, Sumitomo 3M Co., Ltd.) can be used as a commercial product equivalent 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 Limited).

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 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 are "WV film" (manufactured by FUJIFILM Corporation), "NH film" (Shin Nippon Oil Co., Ltd.) And “NR Film” (manufactured by Nippon Oil 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.), “Zeonor Film” (Nippon Zeon ( Etc.).

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, the tensile modulus at 80 ° C. of the film and the crystallinity of the film surface layer were determined by the following methods.

<Tensile modulus at 80 ° C>
A strip-shaped test piece having a length of 100 mm and a width of 40 mm was cut with the film conveyance direction (MD) as the length direction, and measured using a universal testing machine “Autograph AG-I” manufactured by Shimadzu Corporation. This testing machine has a removable thermostat. First, the thermostat in the testing machine was set to 80 ° C., and the direction of the test piece having a length of 100 mm was taken as the tensile direction and held at an initial chuck distance of 80 mm and held for 1 hour or longer. While being kept in the tank, a tensile test was performed at a tensile speed of 30 mm / min, and a tensile modulus was calculated.

<Crystallinity of film surface layer>
Using the following apparatus, the infrared spectroscopic spectrum of the film surface layer was determined by the following specifications and measurement procedures, and the equation shown above from the infrared spectroscopic spectrum:
Crystallinity X (%) = 109 × (A ₉₉₈ -A ₉₂₀ ) / (A ₉₇₄ -A ₉₂₀ ) -31.4
(A ₉₉₈ , A _974, and A ₉₂₀ in the formula are as defined above.)
Was used to calculate the crystallinity X.

Apparatus: Microscopic Fourier transform infrared spectrophotometer “FTS-7000 / UMA600 (microscopic unit)” manufactured by Agilent,
Measurement mode: ATR method (prism: Ge, incident angle: 30 °),
・ Resolution: 4cm ^-1
・ Total number of times: 128 times
ATR-IR measurement procedure: The surface of a base film made of a polypropylene multilayer film was directly pressed against a Ge (germanium) crystal prism, and an infrared spectrum was obtained.

<Example 1>
(1) Production of base film On both sides of a resin layer comprising a random copolymer of propylene / ethylene containing about 5% by weight of an ethylene unit (“Sumitomo Noblen W151” manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 138 ° C.) A long polypropylene-based multilayer film having a three-layer structure in which a resin layer made of homopolypropylene, a homopolymer of propylene (“Sumitomo Nobrene FLX80E4” manufactured by Sumitomo Chemical Co., Ltd., melting point Tm = 163 ° C.), It was produced by coextrusion using a multilayer extruder. The total thickness of the polypropylene multilayer film was 100 μm, and the thickness ratio of each layer (FLX80E4 / W151 / FLX80E4) was 3/4/3.

Next, the polypropylene multilayer film was heat-treated. Specifically, first, while transporting this polypropylene-based multilayer film, it was brought into contact with a hot roll at 70 ° C. for about 10 seconds (first stage of heat treatment) and then placed in an oven at 80 ° C. for one minute (two stages of heat treatment). Eye), and then heat-treated by staying in an oven at 100 ° C. for 1 minute (heat treatment 3rd stage) to obtain a base film. The maximum heat treatment temperature in this heat treatment step is 100 ° C. in the third stage. About this base film, the tensile elasticity modulus in 80 degreeC and the crystallinity degree of the surface layer were calculated | required, and the result shown in Table 1 was obtained.

(2) Formation of primer layer and polyvinyl alcohol resin layer (production of laminated film)
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 is mixed with a crosslinking agent (“Smile Resin 650” manufactured by Taoka Chemical Co., Ltd.) at a ratio of 1 part by weight with respect to 2 parts by weight of the solid content of polyvinyl alcohol. A liquid was obtained.

Further, polyvinyl alcohol powder (“PVA124” manufactured by Kuraray Co., Ltd., average polymerization degree 2400, average saponification degree 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C. A coating solution for forming a polyvinyl alcohol-based resin layer, which is an aqueous alcohol solution, was prepared.

Next, while continuously conveying the base film subjected to the heat treatment in (1) above, one surface thereof is subjected to corona treatment, and then the primer layer is coated on the corona-treated surface using a micro gravure coater. The primer coating liquid was continuously applied and dried at 80 ° C. for 3 minutes to form a primer layer having a thickness of 0.2 μm. Subsequently, while transporting the film, the above-mentioned coating solution for forming the polyvinyl alcohol-based resin layer was continuously applied onto the primer layer using a comma coater, and then at 90 ° C. for 1 minute, at 70 ° C. for 3 minutes, and then A polyvinyl alcohol resin layer having a thickness of 10.0 μm was formed on the primer layer by drying at 60 ° C. for 4 minutes to obtain a laminated film.

The maximum temperature during drying in the primer layer forming step is 80 ° C. as described above, and the maximum temperature during drying in the resin layer forming step is 90 ° C. In any of the drying steps, defects such as wrinkles and folding did not occur in the base film, and drying could be performed without any problem.

(3) Production of stretched film While continuously transporting the laminated film obtained in (2) above, 5.8 in the longitudinal direction (film transport direction) at a stretching temperature of 160 ° C. using an inter-roll air stretcher. Free end uniaxial stretching was performed at a double magnification to obtain a stretched film. The thickness of the polyvinyl alcohol resin layer in the stretched film was 5.0 μm. No particular problems were found in the stretching process.

(4) Production of Polarizing Laminated Film While continuously stretching the stretched film obtained in (3) above, dipping in a warm water bath at 60 ° C. so that the residence time is 60 seconds, then iodine and iodide The polyvinyl alcohol resin layer was dyed by dipping in a dyeing solution containing potassium at 30 ° C. so that the residence time was about 150 seconds, and then the excess dyeing solution was washed away with 10 ° C. pure water. Subsequently, a crosslinking treatment was performed by dipping in a crosslinking solution at 76 ° C. containing boric acid and potassium iodide so that the residence time was 600 seconds. Thereafter, the polarizing laminate film was obtained by washing with pure water at 10 ° C. for 4 seconds and drying at 80 ° C. for 300 seconds.

(5) Production of Polarizing Plate 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 a crosslinking agent (“Smileze Resin 650” manufactured by Taoka Chemical Industry Co., Ltd.) at a ratio of 1 part by weight to 2 parts by weight of the solid content of polyvinyl alcohol to obtain an adhesive solution.

Next, while continuously transporting the polarizing laminated film obtained in (4) above, the adhesive solution was applied onto the polarizer layer, and then the saponification treatment was applied to the bonding surface. An acetylcellulose (TAC) film (“KC4UY” manufactured by Konica Minolta Opto Co., Ltd., thickness 40 μm) is bonded to the adhesive solution coating surface on the polarizer layer, and crimped by passing between a pair of bonding rolls. A laminated film was obtained. Subsequently, the base film was peeled and removed from the bonded film to obtain a polarizing plate in which a protective film made of a TAC film was laminated on the polarizer layer via an adhesive layer. At this time, the base film could be easily peeled off.

<Example 2>
(1) Production of base film As in (1) of Example 1, except that heat treatment was carried out by bringing the polypropylene multilayer film into contact with a 90 ° C. hot roll for about 10 seconds while carrying the polypropylene-based multilayer film. A base film was obtained. In this heat treatment step, the heat treatment operation is only one stage using a heat roll, and the maximum temperature of the heat treatment is 90 ° C. About this base film, the tensile elasticity modulus in 80 degreeC and the crystallinity degree of the surface layer were calculated | required, and the result shown in Table 1 was obtained.

(2) Formation of primer layer and polyvinyl alcohol resin layer (production of laminated film)
The same as (2) of Example 1 except that the base film subjected to the heat treatment in (1) was subjected to corona treatment on both sides and a primer layer and a polyvinyl alcohol-based resin layer were formed on both sides. To obtain a laminated film. The thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on one surface are 0.2 μm and 10.5 μm, respectively, and the thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on the other surface are each 0.00 mm. 2 μm and 11.0 μm.

The maximum temperature during drying in the primer layer forming step is 80 ° C., and the maximum temperature during drying in the resin layer forming step is 90 ° C. In any of the drying steps, defects such as wrinkles and folding did not occur in the base film, and drying could be performed without any problem.

(3) Production of stretched film and polarizing laminated film Using the laminated film obtained in (2) above, a stretched film was produced in the same manner as in (1) of Example 1, and further, (4 of Example 1). ) To produce a polarizing laminated film. The thicknesses of the polyvinyl alcohol resin layers on both sides of the stretched film were 5.0 μm and 5.6 μm, respectively. No particular problems were found in the stretching process.

(4) Production of polarizing plate The same procedure as in (5) of Example 1 except that the polarizing laminate film produced in (3) above was used and a protective film was bonded to each of the polarizer layers on both sides. A laminated film was produced. Subsequently, the base film was peeled and removed from the bonded film to obtain two polarizing plates in which a protective film was laminated on the polarizer layer via an adhesive layer. At this time, the base film could be easily peeled off.

<Example 3>
(1) Production of base film After transporting a polypropylene-based multilayer film, it was brought into contact with a 90 ° C. hot roll for about 7 seconds (first heat treatment) and then allowed to stay in an oven at 100 ° C. for 2 minutes (heating) A base film was produced in the same manner as (1) of Example 2 except that the heat treatment was performed by the second step). In this heat treatment step, the maximum heat treatment temperature is 100 ° C. in the second stage. About this base film, the tensile elasticity modulus in 80 degreeC and the crystallinity degree of the surface layer were calculated | required, and the result shown in Table 1 was obtained.

(2) Formation of primer layer and polyvinyl alcohol resin layer (production of laminated film)
A laminated film was obtained in the same manner as (2) of Example 2 except that the base film subjected to the heat treatment in (1) was used. The thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on one surface are 0.3 μm and 10.5 μm, respectively, and the thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on the other surface are each 0.00 mm. 2 μm and 10.8 μm.

The maximum temperature during drying in the primer layer forming step is 80 ° C., and the maximum temperature during drying in the resin layer forming step is 90 ° C. In any of the drying steps, defects such as wrinkles and folding did not occur in the base film, and drying could be performed without any problem.

(3) Production of stretched film and polarizing laminated film Using the laminated film obtained in (2) above, a stretched film and further a polarizing laminated film were produced in the same manner as in (3) of Example 2. The thicknesses of the polyvinyl alcohol resin layers on both sides of the stretched film were 5.1 μm and 5.5 μm, respectively. No particular problems were found in the stretching process.

(4) Production of polarizing plate A laminated film is produced in the same manner as (4) in Example 2 except that the polarizing laminated film produced in (3) above is used, and the substrate film is peeled and removed therefrom. Thus, two polarizing plates in which a protective film was laminated on the polarizer layer via an adhesive layer were obtained. At this time, the base film could be easily peeled off.

<Example 4>
(1) Production of substrate film The substrate was formed in the same manner as (1) of Example 2 except that heat treatment was carried out by retaining the polypropylene-based multilayer film in an oven at 110 ° C. for 2 minutes. A material film was prepared. In this heat treatment step, the heat treatment operation is performed only in one stage using an oven, and the maximum heat treatment temperature is 110 ° C. About this base film, the tensile elasticity modulus in 80 degreeC and the crystallinity degree of the surface layer were calculated | required, and the result shown in Table 1 was obtained.

(2) Formation of primer layer and polyvinyl alcohol resin layer (production of laminated film)
A laminated film was obtained in the same manner as (2) of Example 2 except that the base film subjected to the heat treatment in (1) was used. The thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on one surface are 0.3 μm and 10.7 μm, respectively, and the thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on the other surface are each 0.00 mm. 3 μm and 11.0 μm.

The maximum temperature during drying in the primer layer forming step is 80 ° C., and the maximum temperature during drying in the resin layer forming step is 90 ° C. In any of the drying steps, defects such as wrinkles and folding did not occur in the base film, and drying could be performed without any problem.

(3) Production of stretched film and polarizing laminated film Using the laminated film obtained in (2) above, a stretched film and further a polarizing laminated film were produced in the same manner as in (3) of Example 2. The thicknesses of the polyvinyl alcohol resin layers on both sides of the stretched film were 5.2 μm and 5.5 μm, respectively. No particular problems were found in the stretching process.

(4) Production of polarizing plate A laminated film is produced in the same manner as (4) in Example 2 except that the polarizing laminated film produced in (3) above is used, and the substrate film is peeled and removed therefrom. Thus, two polarizing plates in which a protective film was laminated on the polarizer layer via an adhesive layer were obtained. At this time, the base film could be easily peeled off.

<Example 5>
(1) Preparation of base film 3% by weight of a nucleating agent made of high-density polyethylene on homopolypropylene (Sumitomo Chemical Co., Ltd. “Sumitomo Nobrene FLX80E4”, melting point Tm = 163 ° C.), which is a propylene homopolymer. Blended to produce polypropylene with nucleating agent. From this and the same propylene / ethylene random copolymer “Sumitomo Nobrene W151” used in (1) of Example 1, from the “Sumitomo Noblen W151” by coextrusion molding using a multilayer extrusion molding machine. A long polypropylene-based multilayer film having a three-layer structure in which the resin layer made of the above nucleating agent-containing polypropylene was disposed on both sides of the resulting resin layer was used as a base film. The total thickness of this base film was 100 μm, and the thickness ratio of each layer (polypropylene with nucleating agent / W151 / polypropylene with nucleating agent) was 3/4/3. About this base film, the tensile elasticity modulus in 80 degreeC and the crystallinity degree of the surface layer were calculated | required, and the result shown in Table 1 was obtained.

(2) Formation of primer layer and polyvinyl alcohol resin layer (production of laminated film)
A laminated film was obtained in the same manner as (2) of Example 2 except that the base film prepared in (1) was used. The thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on one surface are 0.3 μm and 11.1 μm, respectively, and the thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on the other surface are each 0.00 mm. 3 μm and 11.3 μm. In any of the drying steps in the primer layer forming step and the resin layer forming step, the base film was free from defects such as wrinkles and folds, and could be dried without any problem.

(3) Production of stretched film and polarizing laminated film Using the laminated film obtained in (2) above, a stretched film and further a polarizing laminated film were produced in the same manner as in (3) of Example 2. The thicknesses of the polyvinyl alcohol resin layers on both sides of the stretched film were 5.5 μm and 5.6 μm, respectively. No particular problems were found in the stretching process.

(4) Production of polarizing plate A laminated film is produced in the same manner as (4) in Example 2 except that the polarizing laminated film produced in (3) above is used, and the substrate film is peeled and removed therefrom. Thus, two polarizing plates in which a protective film was laminated on the polarizer layer via an adhesive layer were obtained. At this time, the base film could be easily peeled off.

<Example 6>
(1) Production of base film A polypropylene multilayer film was produced by the same method as (1) of Example 5 except that the blending amount of the nucleating agent was 1% by weight to obtain a base film. About this base film, the tensile elasticity modulus in 80 degreeC and the crystallinity degree of the surface layer were calculated | required, and the result shown in Table 1 was obtained.

(2) Formation of primer layer and polyvinyl alcohol resin layer (production of laminated film)
A laminated film was obtained in the same manner as (2) of Example 2 except that the base film prepared in (1) was used. The thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on one surface are 0.2 μm and 10.1 μm, respectively, and the thicknesses of the primer layer and the polyvinyl alcohol resin layer formed on the other surface are each 0.00 mm. It was 3 μm and 10.5 μm. In any of the drying steps in the primer layer forming step and the resin layer forming step, the base film was free from defects such as wrinkles and folds, and could be dried without any problem.

(3) Production of stretched film and polarizing laminated film Using the laminated film obtained in (2) above, a stretched film and further a polarizing laminated film were produced in the same manner as in (3) of Example 2. The thicknesses of the polyvinyl alcohol resin layers on both sides of the stretched film were 4.8 μm and 5.1 μm, respectively. No particular problems were found in the stretching process.

(4) Production of polarizing plate A laminated film is produced in the same manner as (4) in Example 2 except that the polarizing laminated film produced in (3) above is used, and the substrate film is peeled and removed therefrom. Thus, two polarizing plates in which a protective film was laminated on the polarizer layer via an adhesive layer were obtained. At this time, the base film could be easily peeled off.

<Comparative Example 1>
(1) Production of base film As in (1) of Example 1, except that heat treatment was carried out by bringing a polypropylene multilayer film into contact with a heat roll at 70 ° C. for about 10 seconds while carrying the polypropylene-based multilayer film. A base film was obtained. In this heat treatment step, the heat treatment operation is only one stage using a heat roll, and the maximum heat treatment temperature is 70 ° C. About this base film, the tensile elasticity modulus in 80 degreeC and the crystallinity degree of the surface layer were calculated | required, and the result shown in Table 1 was obtained.

(2) Formation of primer layer and polyvinyl alcohol resin layer (production of laminated film)
The substrate film subjected to the heat treatment in the above (1) is subjected to corona treatment on one side while being continuously conveyed in the same manner as in (2) of Example 1, and then the micron is applied to the surface subjected to the corona treatment. Using the gravure coater, the same primer layer coating solution as used in (2) of Example 1 was continuously applied and dried at 80 ° C. for 3 minutes to form a primer layer. During this drying, the base film was wrinkled and folded. The wrinkles here are fine streaks generated by shrinking the surface of the base film due to heat, and the wrinkles are such that they disappear when the film is taken out of the line and pinched by hand. On the other hand, the folds are severely wrinkled and completely creased, and even if the film is taken out of the line and stretched by hand, the crease does not disappear.

Next, using the comma coater on the primer layer, the same coating liquid for forming the polyvinyl alcohol-based resin layer as that used in (2) of Example 1 was continuously applied, and then at 80 ° C. for 4 minutes, Dry at 70 ° C. for 2 minutes. At this time, the coating liquid accumulated in the wrinkle portion, and the portion was poorly dried. The maximum temperature during drying in the primer layer forming step and the resin layer forming step is 80 ° C.

<Comparative example 2>
(1) Production of Base Film The polypropylene multilayer film produced in (1) of Example 1 was used as it was as a base film without heat treatment. About this base film, the tensile elasticity modulus in 80 degreeC and the crystallinity degree of the surface layer were calculated | required, and the result shown in Table 1 was obtained.

(2) Formation of primer layer While the substrate film of (1) above is continuously conveyed in the same manner as in (2) of Example 1, the one side is subjected to corona treatment, and then the corona treatment is applied to the microscopic surface. Using the gravure coater, the same primer layer coating solution as used in (2) of Example 1 was continuously applied and dried at 80 ° C. for 3 minutes to form a primer layer. At this time, wrinkles and folds were generated in the base film during drying, and the coating liquid accumulated in the folds, resulting in uneven thickness. In addition, the wrinkled part caused poor drying due to the increased thickness of the coating solution.

In Table 1, the meanings of “OK” and “NG” in the determination column are as follows.
OK: The base material film satisfies the provisions of the present invention, and can be dried without problems without causing defects such as wrinkles and folds.
NG: The base film does not satisfy the provisions of the present invention, and wrinkles or folds occur during drying, resulting in poor drying.

100 laminated film, 101 substrate film, 101a substrate film surface layer, 102 polyvinyl alcohol resin layer, 200 stretched film, 201 stretched substrate film, 202 stretched polyvinyl alcohol resin layer, 300 polarizing laminate film 301, base film after dyeing process, 302 polarizer layer.

Claims (13)

1. A base film made of a thermoplastic resin and a polyvinyl alcohol resin layer formed by coating on at least one surface of the base film, and the base film has a tensile elastic modulus at 80 ° C. of 140 MPa or more. Is a laminated film.
2. In the base film, at least the surface layer on which the polyvinyl alcohol-based resin layer is formed is composed of a crystalline thermoplastic resin, and the surface layer composed of the crystalline thermoplastic resin has a crystallinity of 58% or more. The laminated film according to claim 1.
3. The laminated film according to claim 2, wherein the surface layer composed of the crystalline thermoplastic resin of the base film contains a nucleating agent.
4. 4. The laminated film according to claim 1, wherein the polyvinyl alcohol-based resin layer has a thickness of 3 to 30 μm.
5. The uniaxially stretched film as it is, and then used to produce a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer with a dichroic dye to form a polarizer layer. The laminated film according to any one of the above.
6. A stretching step of uniaxially stretching the laminated film according to any one of claims 1 to 4 to obtain a stretched film;
   A dyeing step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer;
   A method for producing a polarizing laminate film.
7. A base film preparation step of preparing a base film made of a thermoplastic resin film having a tensile elastic modulus at 80 ° C. of 140 MPa or more;
   After applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film, a resin layer forming step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer by drying;
   A stretching process for obtaining a stretched film by uniaxially stretching the resulting laminated film;
   A dyeing step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer;
   A method for producing a polarizing laminate film.
8. A base film preparation step for obtaining a base film by heat-treating a thermoplastic resin film;
   After applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the obtained base film, a resin layer forming step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer by drying,
   A stretching process for obtaining a stretched film by uniaxially stretching the resulting laminated film;
   A dyeing step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer;
   With
   The said base film preparation process is a manufacturing method of a light-polarizing laminated film including the process of heat-processing the said thermoplastic resin film at the temperature more than the drying temperature in the said resin layer formation process.
9. Between the base film preparation step and the resin layer formation step, by applying a primer layer-forming coating solution on the surface of the base film to which the coating solution is applied, and then drying. A primer layer forming step of forming a primer layer;
   The said base film preparation process is a manufacturing method of the polarizing laminated film of Claim 8 including the process of heat-processing the said thermoplastic resin film at the temperature more than the drying temperature in the said primer layer formation process.
10. A base film preparation step for preparing a base film made of a thermoplastic resin film in which the surface layer on which the polyvinyl alcohol-based resin layer is formed at least in the next step is composed of a crystalline thermoplastic resin containing a nucleating agent When,
    After applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film, a resin layer forming step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer by drying;
    A stretching process for obtaining a stretched film by uniaxially stretching the resulting laminated film;
    A dyeing step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of the obtained stretched film with a dichroic dye to form a polarizer layer;
    A method for producing a polarizing laminate film.
11. The method for producing a polarizing laminated film according to any one of claims 6 to 10, wherein the laminated film is uniaxially stretched at a stretch ratio of more than 5 times.
12. 12. The method for producing a polarizing laminated film according to claim 6, wherein the polyvinyl alcohol resin layer in the laminated film has a thickness of 3 to 30 μm.
13. Preparing a polarizing laminated film obtained by the production method according to any one of claims 6 to 12,
    A step of bonding a protective film on the polarizer layer in the polarizing laminated film to obtain a bonding film;
    A step of peeling the substrate film from the obtained bonding film;
    The manufacturing method of a polarizing plate provided with.

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