KR20160117126A - Laminated film, method for manufacturing laminated film, method for manufacturing polarizing laminated film and method for manufacturing polarizing plate - Google Patents

Abstract

Provided are a laminated film, a manufacturing method of the laminated film, a method for manufacturing a polarizing laminated film from the laminated film, and a method for manufacturing a polarizing plate from the laminated film. The laminated film is formed with a resin layer formed of a polyvinyl alcohol-based resin on a substrate film, and does not generate the unevenness of optical stripes when being introduced in the polarizing plate. The laminated film is formed with a resin layer formed of a polyvinyl alcohol-based resin on a gauge rod-type substrate film. The maximum amplitude of the thickness in the width direction of the resin layer is less than or equal to 2.0 m.

Description

TECHNICAL FIELD [0001] The present invention relates to a laminated film, a laminated film, a method for producing a laminated film, a method for producing a polarizing laminated film, and a method for producing a polarizing plate. [0002] LAMINATED FILM, METHOD FOR MANUFACTURING LAMINATED FILM, METHOD FOR MANUFACTURING POLARIZING LAMINATED FILM AND METHOD FOR MANUFACTURING POLARIZING PLATE,

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

Conventional polarizers are prepared by stretching and dyeing original film of polyvinyl alcohol resin (usually about 30 to 75 mu m in thickness), and the thickness of the stretched film is usually about 12 to 30 mu m. When a film having a thickness of 30 占 퐉 or less is used as the original film of a polyvinyl alcohol-based resin for thinning, there is a problem in productivity such that the film tends to be broken at the time of stretching.

Therefore, in order to cope with the thinning of the polarizing plate recently, a method of coating an aqueous solution containing a polyvinyl alcohol resin on a base film has been proposed. In this method, a resin layer made of a polyvinyl alcohol resin is formed by coating an aqueous solution containing a polyvinyl alcohol resin on a base film to obtain a laminated film, and then the laminated film is subjected to stretching and dyeing treatment A polarizing function is imparted to a resin layer made of a polyvinyl alcohol resin to obtain a polarizer layer (Patent Documents 1 and 2).

In a polarizing plate obtained by coating an aqueous solution containing a polyvinyl alcohol resin on the base film, there arises a problem that optical stripes are unevenly formed on the polarizing plate. The same problem also occurs in the polarizing plate obtained from the original film of the polyvinyl alcohol resin, and it has been found that the cause is the thickness irregularity of the original film of the polyvinyl alcohol resin (Patent Document 3).

However, in the method of coating an aqueous solution containing a polyvinyl alcohol-based resin on a base film, the thickness of the resin layer made of polyvinyl alcohol-based resin is measured by the following two methods, and the accurate polyvinyl alcohol It is difficult to measure the thickness of the resin layer made of the resin as well as the thickness irregularity. Therefore, it was impossible to find the cause of the optical nonuniformity of the striations and to find a way to control the cause thereof.

(Method 1) A method of peeling a resin layer made of a polyvinyl alcohol resin from a base film and measuring the thickness of the peeled polyvinyl alcohol-based resin layer. In this method, the resin layer made of the polyvinyl alcohol resin may be stretched at the time of peeling.

(Method 2) The thickness of the laminated film before peeling of the resin layer made of the polyvinyl alcohol resin and the thickness of the base film after peeling are measured, and the thickness of the resin layer made of polyvinyl alcohol resin is calculated from the difference Way. In this method, the measurement position may be shifted.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2011-150313 Patent Document 2: Japanese Patent Laid-Open Publication No. 1539778 Patent Document 3: Japanese Patent Application Laid-Open No. 2002-28941

The present invention relates to a laminated film on which a resin layer made of a polyvinyl alcohol resin is formed on a base film and which does not cause optical banding unevenness when introduced into a polarizing plate, a method for producing such a laminated film, A method for producing a polarizing laminated film, and a method for producing a polarizing plate from such a laminated film.

The present invention includes the following.

[1] A laminated film in which a resin layer made of polyvinyl alcohol resin is formed on a long base film,

And the maximum amplitude of the thickness in the width direction of the resin layer is not more than 2.0 mu m.

[2] The laminated film according to [1], wherein the periodic intensity of the film thickness distribution in the width direction of the resin layer is 0.09 or less.

[3] A laminated film according to [1] or [2], wherein the average value of the thickness in the transverse direction of the resin layer is 10 m or less.

[4] A method for producing a laminated film according to any one of [1] to [3], which comprises the following steps (1-1) and (2-1).

Process (1-1) A coating process for obtaining a base film having a coating layer by coating an aqueous solution containing a polyvinyl alcohol resin on a base film to form a coating layer

(2-1) A substrate film having a coating layer is conveyed to a drying zone. In the drying zone, while the substrate film having a coating layer is supported by at least one guide roll, the coating layer is dried to form a polyvinyl alcohol resin And a drying step of obtaining a laminated film

[5] A method for producing a laminated film according to any one of [1] to [3], which comprises the following steps (1-2) and step (2-2).

Process (1-2) A coating process for obtaining a base film having a coating layer by coating an aqueous solution containing a polyvinyl alcohol resin on a base film to form a coating layer

Step (2-2) A base film having a coating layer is conveyed to a drying zone in a floating manner to dry the coating layer to form a resin layer made of a polyvinyl alcohol resin having a thickness of 10 占 퐉 or less, As a drying step to be obtained,

Wherein the dew point of the atmosphere in the drying zone is a drying step

[6] A method for producing a polarizing laminated film comprising the following steps (3) and (4).

Step (3) A stretching process for obtaining a stretched laminated film by uniaxially stretching the laminated film according to any one of [1] to [3]

Step (4) Dyeing process for obtaining a polarizing laminated film having a polarizer layer and a base film by dyeing the oriented laminated film

[7] A method for producing a polarizing plate, which comprises the following steps (3) to (6).

Step (3) A stretching process for obtaining a stretched laminated film by uniaxially stretching the laminated film according to any one of [1] to [3]

Step (4) Dyeing process for obtaining a polarizing laminated film having a polarizer layer and a base film by dyeing the oriented laminated film

(5) A bonding process for bonding a transparent protective film to a polarizer layer in a polarizing laminated film to obtain a multilayered film

Step (6) A peeling step of peeling the base film from the multilayer film to obtain a polarizer and a polarizing plate having a transparent protective film

[8] A method for producing a single sheet of a polarizing plate, which comprises the following step (7).

Step (7) Cutting the polarizing plate described in [7] into a rectangular shape, thereby obtaining a cutting step of obtaining each polarizing plate

According to the laminated film of the present invention, it is possible to obtain a polarizing plate free from optical unevenness in stripe pattern.

1 is a schematic view showing an example of a method of supporting a base film having a coating layer by a guide roll.
2 is a schematic view showing an example of a method of supporting a base film having a coating layer by a guide roll.
3 is a schematic view showing an example of a method of supporting a base film having a coating layer by a guide roll.
4 is a schematic view showing an example of a method of supporting a base film having a coated layer in a floating state in the air.

The inventors of the present invention measured the film thickness of a resin layer made of a polyvinyl alcohol resin by an interference film thickness meter and found that the cause of optical banding unevenness was caused by the fact that the width of a resin layer made of a long polyvinyl alcohol- It has been found that the maximum amplitude of the thickness is greater than 2.0 [mu] m. In the measurement of the thickness by the interference film thickness meter, there is no need to peel off the resin layer made of the polyvinyl alcohol resin from the base film as in the conventional method, and the measurement position is not deviated. Therefore, the thickness of the resin layer made of polyvinyl alcohol resin can be accurately measured.

Therefore, the maximum amplitude in the width direction in the resin layer made of the polyvinyl alcohol resin of the laminated film of the present invention is 2.0 占 퐉 or less. The maximum amplitude is preferably 1.7 占 퐉 or less, more preferably 1.5 占 퐉 or less, and further preferably 1.3 占 퐉 or less in view of being capable of further suppressing optical banding unevenness. Normally, the maximum amplitude is 0.2 탆 or more.

In this specification, the width direction refers to a direction perpendicular to the longitudinal direction of the elongated laminated film and parallel to the laminated film surface. When the laminated film is produced by the roll-to-roll method, the width direction is perpendicular to the conveying direction (MD direction) of the laminated film, and coincides with the direction parallel to the laminated film surface, that is, the TD direction. Naturally, the longitudinal direction coincides with the MD direction. When the laminated film of the present invention is subjected to a treatment including a stretching treatment and a dyeing treatment to obtain a polarizing laminated film, the stretching direction generally coincides with the longitudinal direction of the laminated film, and absorption of the polarizing laminated film The axial direction coincides with the longitudinal direction of the laminated film. This relationship is also applicable to a polarizing plate in which a transparent protective film is bonded to a polarizing laminated film and a base film is peeled off. The same holds true for each polarizing plate cut into a predetermined size.

In the present specification, the maximum amplitude refers to a value measured by the following method. First, the thickness of the laminated film in the width direction is measured by an interference film thickness meter so that the measurement interval is 0.05 mm or more and 2 mm or less. With this measurement interval, it is possible to accurately detect the difference in the thickness amplitude which causes optical nonuniformity of the stripes. The thickness is measured over the entire width in the width direction of the resin layer made of the polyvinyl alcohol resin in the laminated film. When the thickness of the resin layer made of polyvinyl alcohol resin is measured only in a part of the width in the width direction, there is a possibility that the difference in the thickness amplitude which causes optical nonuniformity of the stripes may not be detected. The magnitude of the difference between the largest peak and the largest peak in the thickness profile thus obtained is called the maximum amplitude.

Further, it is preferable that the resin layer made of the polyvinyl alcohol resin does not have a periodic structure in the profile in the thickness direction in the width in that the optical banding unevenness can be further suppressed. Therefore, in the laminated film of the present invention, the periodic intensity of the film thickness distribution in the width direction of the resin layer made of polyvinyl alcohol resin is preferably 0.09 or less, more preferably 0.065 or less, and still more preferably 0.050 or less. The period intensity of the film thickness distribution in the normal width direction is 0.00 or more. In the present invention, the periodic intensity of the film thickness distribution means a value obtained by the following method. First, the thickness profile obtained in the above-described manner in the width direction is subjected to fast Fourier transform. In the wave spectrum obtained as described above, the periodic intensity of the film thickness distribution refers to the value of the maximum amplitude in the region where the period is 30 to 70 mm.

Hereinafter, a method of producing a laminated film of the present invention, a method of producing a polarizing laminated film, and a method of producing a polarizing plate will be described.

The laminated film of the present invention can be produced by the following steps (1-1) and (2-1), or a step including steps (1-2) and (2-2). Hereinafter, each process will be described. In this specification, the step (1-1) and the step (1-2) are collectively referred to as the step (1). In this specification, the step (2-1) and the step (2-2) are collectively referred to as the step (2).

Process (1-1) A coating process for obtaining a base film having a coating layer by coating an aqueous solution containing a polyvinyl alcohol resin on a base film to form a coating layer

Step (2-1) A drying step of drying a coated layer by transporting a substrate film having a coated layer to a drying zone to form a resin layer made of a polyvinyl alcohol resin, and obtaining a laminated film, The base film having a coating layer is formed by a drying process carried out by at least one guide roll

Process (1-2) A coating process for obtaining a base film having a coating layer by coating an aqueous solution containing a polyvinyl alcohol resin on a base film to form a coating layer

Step (2-2) A base film having a coating layer is conveyed to a drying zone in a floating manner to dry the coating layer to form a resin layer made of a polyvinyl alcohol resin having a thickness of 10 占 퐉 or less, As a drying step to be obtained, a dew point in the drying zone is set to a drying step

[Step (1)]

In the step (1), an aqueous solution containing a polyvinyl alcohol resin is coated on the base film. Particularly in the step (1-2), an aqueous solution containing a polyvinyl alcohol resin is coated on the base film so as to have a thickness of not more than 10 占 퐉 under the step (2-2).

[Base film]

As the resin constituting the base film, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, stretchability and the like is suitably used. Depending on the glass transition temperature (Tg) or melting point (Tm) thereof, . Specific examples of the thermoplastic resin include a polyolefin resin, a polyester resin, a cyclic polyolefin resin (norbornene resin), a (meth) acrylic resin, a cellulose ester resin, a polycarbonate resin, a polyvinyl alcohol resin , Vinyl acetate resin, polyarylate resin, polystyrene resin, polyether sulfone resin, polysulfone resin, polyamide resin, polyimide resin, and mixtures and copolymers thereof.

The base film may be a single layer film using only one of the above-mentioned resins, or may be a blend of two or more kinds of resins. Of course, a multilayer film may be formed instead of a single layer film.

The polyolefin-based resin is a polymer containing, as a main monomer, a chain-like olefin such as ethylene or propylene. A propylene-ethylene copolymer obtained by copolymerizing propylene with ethylene may also be used. The copolymerization may be a monomer other than ethylene, and examples of monomers of other species copolymerizable with propylene include? -Olefins. The? -Olefin copolymerized with propylene has at least 4 carbon atoms, and is preferably an? -Olefin having 4 to 10 carbon atoms. Specific examples of the? -Olefin having 4 to 10 carbon atoms include linear monoolefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-decene; Branched monoolefins such as 3-methyl-1-butene, 3-methyl-1-pentene and 4-methyl-1-pentene; Vinyl cyclohexane and the like. The copolymer of propylene and other monomer copolymerizable therewith may be a random copolymer or a block copolymer. The content of the constituent unit derived from the other monomer in the copolymer can be determined by measuring the infrared (IR) spectrum according to the method described in "Polymer Analysis Handbook" (published by Kenokuniya Shoten Publishing Co., 1995) on page 616 . The polyolefin-based resin is preferably used as the base film in the present invention because it is easy to stably stretch at a high magnification.

Of the polyolefin resins, propylene resins are preferable, and examples thereof include homopolymers of propylene, propylene-ethylene random copolymers, propylene-1-butene random copolymers and propylene-ethylene-1-butene random copolymers have.

The stereoregularity of the propylene resin is preferably substantially isotactic or syndiotactic. A film made of a propylene resin having substantially isotactic or syndiotactic stereoregularity is relatively easy to handle and has excellent mechanical strength under a high temperature environment.

The polyester-based resin is a polymer having an ester bond, and more specifically, it is often composed of a polycondensation product of a polyvalent carboxylic acid and a polyhydric alcohol. The polyvalent carboxylic acid used herein is mainly a dicarboxylic acid, that is, a divalent carboxylic acid, or a lower alkyl ester thereof, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. The polyhydric alcohol to be used is also mainly a diol, that is, a dihydric alcohol, and examples thereof include propanediol, butanediol, neopentyl glycol, cyclohexanedimethanol and the like.

As a representative example of the polyester-based resin, polyethylene terephthalate which is a polycondensation product of terephthalic acid and ethylene glycol can be mentioned. Polyethylene terephthalate is a crystalline resin, but it is easy to carry out a treatment such as stretching in a state before crystallization treatment. If necessary, it may be subjected to crystallization treatment at the time of drawing or after heat treatment after stretching. Further, copolymerized polyesters having reduced crystallinity (or made amorphous) by copolymerizing monomers of still further different species to the skeleton of polyethylene terephthalate are also suitably used. Examples of such resins include copolymers obtained by copolymerizing cyclohexane dimethanol or isophthalic acid. These resins can also be suitably used because they are excellent in stretchability.

Specific examples of the polyester resin other than the polyethylene terephthalate and the copolymer thereof include polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate , Polycyclohexanedimethanol naphthalate, and the like. These blend resins and copolymers can also be used.

The cyclic polyolefin-based resin is a generic name of a polymer having a cyclic olefin as a main constituent monomer, and examples thereof include: JP-A-1-240517, JP-A-3-14882, JP-A-3-122137 And resins described in, for example, JP-A-2004-346991. Specific examples thereof include a ring-opening (co) polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer (typically a random copolymer) of a cyclic olefin and an -olefin such as ethylene or propylene, Graft polymers modified with a carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of cyclic olefins include norbornene monomers. As the cyclic polyolefin-based resin, a norbornene-based resin is particularly preferably used.

As the cyclic polyolefin-based resin, various products are commercially available. Specific examples include TOPAS (manufactured by Topas Advanced Polymers GmbH), ATON (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), Zeonex (registered trademark) (Manufactured by Nippon Zeon Co., Ltd.) and APEL (registered trademark) (manufactured by Mitsui Chemicals, Inc.).

The (meth) acrylic resin is a polymer mainly composed of a compound having a (meth) acryloyl group. Examples thereof include polymethacrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate- (meth) acrylic acid ester copolymers, methyl methacrylate- ) Acrylic acid copolymer, a methyl methacrylate-styrene copolymer (referred to as MS resin), a copolymer of methyl methacrylate and a compound having an alicyclic hydrocarbon group (e.g., methacrylic acid methyl- (meth) acrylate Hexyl copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, and the like). Preferably, a polymer containing a C ₁ -C ₆ alkyl ester of methacrylic acid as a main component, such as methyl polymethacrylate, can be mentioned. A more preferable example of the (meth) acrylic resin is a methyl methacrylate resin having methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of such a cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Also, copolymers thereof and those obtained by modifying a part of the hydroxyl groups with other substituents are also cited. Of these, cellulose triacetate is particularly preferable. Many products of cellulose triacetate film are commercially available, and are advantageous in terms of availability and cost. Examples of commercially available products of the cellulose triacetate film include Fujitac (registered trademark) TD80 (manufactured by Fuji Film), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UZ KC8U2M (manufactured by Konica Minolta Co., Ltd.), KC4UY (manufactured by Konica Minolta Co., Ltd.), and the like.

The polycarbonate resin is a polymer having a carbonate bond (-O-CO-O-) in the main chain. As a kind of engineering plastics, it is a resin having high impact resistance, heat resistance and flame retardancy. In addition, since it has high transparency, it is suitably used for optical use. In the optical use, a resin called a modified polycarbonate such as a modified polymer skeleton for lowering the photoelastic coefficient and a copolymerized polycarbonate improved in wavelength dependency are commercially available and can be suitably used. Such a polycarbonate resin is widely available and is commercially available from, for example, Panlite (registered trademark) (manufactured by Dainippon Ink & Chemicals, Inc.), Yuferon (registered trademark) manufactured by Mitsubishi Engineering Plastics Corporation, SD Polycar (registered trademark) (Manufactured by Star Theory Polycarbonate Co., Ltd.) and Kaliba (registered trademark) (manufactured by Sumikastar Theory Polycarbonate Co., Ltd.).

In addition to the thermoplastic resin, any appropriate additives may be added to the base film. Examples of such additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments and colorants. The proportion of the above-mentioned thermoplastic resin in the base film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, particularly preferably 70 to 97% by weight %to be. If the proportion of the thermoplastic resin in the base film is less than 50% by weight, high transparency and the like inherently possessed by the thermoplastic resin may not be sufficiently developed.

The thickness of the base film can be appropriately determined, but it is preferably 1 to 500 占 퐉, more preferably 1 to 300 占 퐉, particularly preferably 5 to 200 占 퐉 in view of workability such as strength and handling properties in general Do. Further, a base film having a thickness in the range of 5 to 150 mu m is most preferable.

The width of the base film is preferably 50 cm or more, and is usually 5 m or less. When the width of the base film is more than 5 m, it is easy to cause a relaxation in the conveyance path, and when the aqueous solution containing the polyvinyl alcohol resin is coated, the distribution of the aqueous solution containing the polyvinyl alcohol- There is a fear that it becomes uneven. Therefore, the maximum amplitude of the thickness in the width direction in the resin layer made of the polyvinyl alcohol resin tends to become large. If the width of the base film is less than 50 cm, the productivity may deteriorate.

The base film may be subjected to a corona treatment, a plasma treatment, a flame treatment, or the like on the surface of the polyvinyl alcohol resin layer on which the polyvinyl alcohol resin layer is formed in order to improve the adhesion with the polyvinyl alcohol-based resin layer.

The tensile modulus of elasticity of the base film at 80 캜 is preferably 180 MPa or more, more preferably 200 MPa or more. The tensile modulus of the base film at high temperature influences the film thickness distribution of the coating layer when an aqueous solution (coating solution) containing a polyvinyl alcohol resin is applied on a base film. By using a base film having a tensile elastic modulus at 80 DEG C of 180 MPa or more, it is possible to prevent the film from loosening in the width direction when drying the coated layer after the coating (step (2)). As a result, the film thickness variation of the resin layer made of the polyvinyl alcohol resin in the width direction is reduced, and more optical nonuniformity of the stripe pattern can be suppressed.

[Primer Layer]

The primer layer may be formed on the base film prior to coating the aqueous solution containing the polyvinyl alcohol resin on the base film. The primer layer may be formed of a material exhibiting a strong adhesion to some extent on both sides of the resin layer made of the base film and the polyvinyl alcohol resin. For example, a thermoplastic resin excellent in transparency, thermal stability, stretchability and the like is used. Specific examples thereof include acrylic resins and polyvinyl alcohol resins.

The resin forming the primer layer may be coated on the base film in a state dissolved in a solvent. In consideration of environmental effects, it is preferable to form a primer layer from a coating solution for forming a primer layer using water as a solvent. The coating liquid for forming the primer layer may contain a crosslinking agent. Examples of the crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, a dialdehyde crosslinking agent, and a metal crosslinking agent.

The ratio of the thermoplastic resin and the crosslinking agent used for forming the primer layer may be suitably determined in accordance with the type of the thermoplastic resin and the type of the crosslinking agent, etc. in the range of about 0.1 to 100 parts by weight of the crosslinking agent relative to 100 parts by weight of the thermoplastic resin, It is preferably selected in the range of about 0.1 to 50 parts by weight. The coating solution for forming a primer layer preferably has a solid concentration of about 1 to 25% by weight. In the present specification, the term "solid content" refers to the sum of the components excluding the solvent.

The thickness of the primer layer is preferably in the range of about 0.05 to 1 mu m, more preferably 0.1 to 0.4 mu m. If the thickness of the primer layer is 0.05 to 1 占 퐉, the adhesion between the base film and the polyvinyl alcohol-based resin layer and the thinning of the polarizing plate can be made compatible.

In the formation of the primer layer, the coating method to be used is not particularly limited, and a coating method such as a wire bar coating method, a roll coating method such as reverse coating or gravure coating, a die coating method, a comma coating method, a lip coating method, Coating method, fountain coating method, dipping method, spray method and the like.

[An aqueous solution containing a polyvinyl alcohol resin]

Examples of the polyvinyl alcohol-based resin include a polyvinyl alcohol resin and derivatives thereof. Examples of derivatives of polyvinyl alcohol resins include polyvinylformal, polyvinyl acetal, etc., polyvinyl alcohol resins modified with olefins such as ethylene and propylene; Modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; An alkyl ester of an unsaturated carboxylic acid; Acrylamide, and the like. The modification ratio is preferably less than 30 mol%, more preferably less than 10 mol%. When the modification is performed in an amount of 30 mol% or more, it becomes difficult to adsorb the dichroic dye, which may cause a problem that the polarization performance is lowered. Among the polyvinyl alcohol resins described above, it is preferable to use a polyvinyl alcohol resin.

The average degree of polymerization of the polyvinyl alcohol resin is preferably in the range of 100 to 10,000, more preferably in the range of 1,000 to 10,000, more preferably in the range of 1,500 to 8,000, and more preferably in the range of 2,000 to 5,000 Is most preferable. The average degree of polymerization can be determined by the method described in JIS K 6726-1994 " Polyvinyl alcohol test method ". When the average degree of polymerization is less than 100, it is difficult to obtain a desired polarizing performance. When the average degree of polymerization is more than 10,000, the solubility in a solvent deteriorates, making it difficult to form a polyvinyl alcohol-based resin layer.

The polyvinyl alcohol resin is preferably a saponified product of a polyvinyl acetate resin. The degree of saponification is preferably 80 mol% or more, more preferably 90 mol% or more, particularly preferably 94 mol% or more. If the degree of saponification is too low, there is a possibility that the water resistance and humidity resistance of the polarizing laminated film or polarizing plate may become insufficient. If the degree of saponification is too high, the dyeing speed is slowed. In order to give sufficient polarizing performance, the production time may be prolonged, and in some cases, sufficient polarization performance may be obtained Or a polarizer having a polarizer may not be obtained. Therefore, the degree of saponification is preferably 99.5 mol% or less, more preferably 99.0 mol% or less.

The degree of saponification is a unit ratio (mol%) of the ratio of the acetic acid group (acetoxy group: -OCOCH ₃ ) contained in the polyvinyl acetate resin as the raw material of the polyvinyl alcohol resin to the hydroxyl group by the saponification treatment, The following formula:

Saponification degree (mol%) = [(number of hydroxyl groups) / (number of hydroxyl groups + number of acetic acid groups)] × 100

.

The higher the degree of saponification, the greater the proportion of hydroxyl groups, and thus the smaller the proportion of acetic acid groups that inhibit crystallization. The degree of saponification can be determined by the method described in JIS K 6726-1994 " Polyvinyl alcohol test method ".

Examples of the polyvinyl acetate-based resin include a copolymer of vinyl acetate, which is a homopolymer of vinyl acetate, and other monomers copolymerizable with vinyl acetate. Other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

PVA124 " (saponification degree: 98.0 to 99.0 mol%) and " PVA117 " (saponification degree: 98.0 to 99.0 mol%) manufactured by Kuraray Co., Ltd. were used as commercial products of commercially available polyvinyl alcohol resins, ), "PVA117H" (saponification degree: not less than 99.5 mol%), "PVA624" (saponification degree: 95.0 to 96.0 mol%) and "PVA617" (saponification degree: 94.5 to 95.5 mol%); AH-26 "(saponification degree: 97.0 to 98.8 mol%)," AH-22 "(saponification degree: 97.5 to 98.5 mol%)," NH-18 "(saponification degree: 98.0 to 98.0 mol%) manufactured by Nippon Synthetic Chemical Industry Co., 99.0 mol%), "N-300" (saponification degree: 98.0 to 99.0 mol%); (Saponification degree: 99.0 mol% or more), JM-33 (saponification degree: 93.5 to 95.5 mol%) and JM-26 (saponification degree: 95.5 to 95.5 mol%) manufactured by Nihon Sakubi Poval Co., JF-17L "(saponification degree: 98.0 to 99.0 mol%) and" JF-17L "(saponification degree: 98.0 to 99.0 mol%) %) And "JF-20" (saponification degree: 98.0 to 99.0 mol%).

The aqueous solution containing the polyvinyl alcohol resin may contain an additive such as a plasticizer and a surfactant if necessary. Examples of the plasticizer include polyols and condensates thereof, and specific 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.

As a method of coating an aqueous solution containing a polyvinyl alcohol resin on a base film, the same method as that for coating a coating solution for forming a primer layer can be mentioned. The aqueous solution containing the polyvinyl alcohol resin may be applied over the full width direction of the base film, or may be applied only to a part in the width direction. As a method for coating only a part in the width direction, there is a method of leaving unexposed portions at both ends of the base film. The aqueous solution containing the polyvinyl alcohol resin is preferably coated with 70% or more of the entire width of the base film, more preferably 90% or more, and more preferably 95% or more.

The thickness of the coating layer is determined by the target thickness after drying and the solid content of the aqueous solution containing the polyvinyl alcohol resin. The thickness of the coating layer is preferably 145 占 퐉 or less, and more preferably 140 占 퐉 or less. By setting the coating layer to 145 m or less, the flowability of the coating liquid can be suppressed on the base film until the step (2) is carried out, and the distribution of the film thickness can be made more uniform. Particularly, It is easy to set the maximum amplitude to 2 mu m or less. The thickness of the coating layer can be obtained by dividing the thickness after drying with a solid content of an aqueous solution containing a polyvinyl alcohol resin.

[Step (2-1)]

In the step (2-1), the base film having the coating layer obtained in the step (1) is conveyed to a drying zone to dry the coating layer. By drying the coating layer, a resin layer made of polyvinyl alcohol resin can be formed. In the step (2-1), in the drying zone, the base film having the coated layer is transported by at least one guide roll. However, when there are two or more drying zones as described later, the base film having the coated layer may be supported by the guide rolls in at least one drying zone.

It is also preferable that the coating layer is solidified at the time of passing through the last drying zone in the step (2-1) to be a resin layer made of a polyvinyl alcohol-based resin. By completing the solidification of the coating layer in the step (2-1), when the laminated film is conveyed to a post-process, or when the laminated film is wound onto a roll, And it is also possible to inhibit the distribution of the aqueous solution containing the polyvinyl alcohol resin from becoming uneven on the base film. If moisture is not felt by contacting the coating layer with a finger, solidification may be considered to be completed.

In this specification, a zone having a function of drying a coating layer such as heating or blowing is referred to as a drying zone. Examples of the drying zone include hot rolling, drying furnace, and air blowing. In the case where the drying zone is a hot roll, the heating roll itself is a drying zone, the drying zone is a drying zone, the drying zone is a drying zone, and the drying zone is air blowing.

As the drying zone in the step (2-1), the above-mentioned hot rolling, drying furnace, and air blowing can be employed. The drying zone in the step (2-1) is preferably a drying furnace, more preferably a roll supporting type drying furnace. Two or more drying zones may be installed in the transport path. Two or more types of drying zones may also be provided. In this case, a combination of the heating roll and the drying furnace, a combination of the drying furnace and the air blowing, and a combination of the heating roll and the air blowing can be mentioned.

The drying with hot roll is achieved by bringing the hot roll into contact with the base film and heating the coated layer, and the hot roll also serves as a guide roll. The drying temperature at the time of drying by the heated roll is preferably 80 to 140 占 폚, more preferably 90 to 120 占 폚. By setting the drying temperature at 80 DEG C or higher, the drying time can be shortened and the productivity can be improved. The drying temperature at the time of drying by the heating roll means the surface temperature of the heating roll. It is preferable that the drying time when drying with hot roll is 30 to 1000 seconds, more preferably 30 to 300 seconds. The drying time at the time of drying by the heating roll means the time during which the film to be transported is in contact with the heating roll.

Drying by blowing is accomplished by spraying wind onto the coated layer on the base film. At this time, in the base film having the coating layer, the wind blowing portion is supported by the guide roll. The drying temperature at the time of drying by air blowing is preferably from 50 to 150 캜, more preferably from 60 to 140 캜. By setting the drying temperature at 50 占 폚 or higher, the drying time can be shortened and the productivity can be improved. The drying temperature at the time of drying by air blowing means the temperature of the air sprayed onto the coating layer. The wind speed is preferably 0.5 to 20 m / s, more preferably 1.0 to 15 m / s. When the wind speed is 0.5 to 20 m / s, the fluctuation of the base film having the coated layer can be suppressed and the drying time can be shortened. Thus, the film thickness distribution in the width direction can be made more uniform, have. The drying time for drying by blowing air is preferably 30 to 1500 seconds, more preferably 180 to 1000 seconds, and still more preferably 360 to 600 seconds. The drying time during drying by blowing is the sum of the time during which the wind is sprayed onto the film being transported.

Drying by a drying furnace is achieved by conveying a base film having a coating layer in a drying furnace. At this time, the base film having the coating layer in the drying furnace is supported by at least one guide roll. The temperature of the atmosphere in the drying furnace at the time of drying the coating layer by the drying furnace is preferably 40 to 130 캜, more preferably 50 to 120 캜. By setting the drying temperature at 40 占 폚 or higher, the drying time can be shortened and the productivity can be improved. The dew point in the drying oven is preferably 50 DEG C or lower, more preferably 47 DEG C or lower. Usually, the dew point in the drying furnace is 0 ° C or higher. By setting the dew point at 50 DEG C or less, the drying efficiency can be further improved and the flow of the coating liquid can be effectively suppressed. The drying time for drying by a drying oven is preferably 30 to 1500 seconds, more preferably 180 to 1000 seconds, and still more preferably 360 to 600 seconds. The drying time when drying is performed by the drying furnace is the sum of the time during which the film to be transported is staying in the drying furnace.

In the step (2-1), the base film having the coating layer in the drying zone is supported by at least one guide roll. In the base film having the coating layer, it is preferable that the base film is held in contact with the guide roll. The number of the guide rolls for supporting the base film having the coating layer in the drying zone is preferably two or more, more preferably seven or more. By supporting the base film having the coating layer in the drying zone by at least one guide roll, the base film having the coating layer is not easily loosened and the distribution of the aqueous solution containing the polyvinyl alcohol resin on the base film is uniform . Therefore, it is easy to reduce the maximum amplitude of the thickness in the width direction in the polyvinyl alcohol-based resin layer.

Hereinafter, a supporting method of a base film having a coating layer by a guide roll will be described with reference to the drawings. However, the present invention is not limited to these examples.

In Fig. 1, a base film 2 having a coating layer is supported by one guide roll 1 in a drying zone. In this case, the drying zone may be a drying zone, a blowing zone or a columnar zone. When the drying zone is a thermal roll, the guide roll 1 may also serve as a thermal roll. 1, when the base film 2 having a coating layer is supported by one guide roll 1 in a drying zone, the base film 2 having a coating layer is sandwiched between the guide rolls 1 And is preferably supported by being wrapped around. In other words, the portion of the base film 2 having the coated layer contacting the guide roll 1 is preferably 5% or more of the surface area of the side edge of the guide roll 1, more preferably 25% or more , Usually not more than 50%. Since the base film 2 having the coating layer is wrapped and supported by the guide roll 1 in this manner, the base film 2 having the coating layer can be transported in a stable state without causing any relaxation, It is easy to reduce the maximum amplitude of the thickness in the width direction in the alcohol-based resin layer. The arrow mark 3 indicates the rotational direction of the guide roll.

When the substrate film 2 having a coating layer is supported by one guide roll 1 as shown in Fig. 1, it is preferable that the diameter of the guide roll 1 is increased. The diameter of the guide roll 1 is preferably 5 to 100 cm, and more preferably 5 to 50 cm. If the diameter of the guide roll 1 is 5 cm or more, the time for which the base film 2 having the coated layer is in contact with the guide roll 1 is set to be longer than the conveying speed of the base film 2 having the coated layer It can be long. Therefore, since the base film 2 having a coating layer can be transported in a stable state without causing relaxation in the base film 2 having a coating layer, the base film 2 having a coating layer can be transported in a widthwise direction of the resin layer made of polyvinyl alcohol- It is easy to reduce the maximum amplitude of the thickness.

2 (a), a base film 2 having a coating layer is supported by three guide rolls 11, 12 and 13 in a drying zone, and three guide rolls are provided in a straight line. In this embodiment, since the base film 2 having the coating layer is supported by the plurality of guide rollers, the maximum amplitude of the thickness in the width direction in the resin layer made of the polyvinyl alcohol resin can be easily reduced. Three guide rolls may be provided at the same height so that the base film 2 having the coated layer is transported horizontally relative to the paper. The guide rolls 11, 12 and 13 are arranged in such a manner that the installation height thereof is increased in the order of the guide rolls 11, 12 and 13, 2 may be conveyed obliquely with respect to the paper surface.

2 (b), a base film 2 having a coated layer is supported by three guide rolls 11, 12 and 13 in a drying zone, and a guide roll 12 at the center is supported by another guide roll (11) and (13). That is, a guide roll is arranged in an arcuate shape in which the guide roll 12 at the center is a vertex. Therefore, a suitable tension can be applied to the base film 2 having the coating layer in the drying zone, and the base film 2 having the coating layer is prevented from being relaxed and the base film 2 having the coating layer in a stable state ), It is easy to reduce the maximum amplitude of the thickness in the width direction in the resin layer made of the polyvinyl alcohol-based resin. Of course, as shown in Fig. 2 (c), the base film 2 having the coated layer is supported by the three guide rolls 11, 12 and 13 in the drying zone, and the guide roll 12 It is possible to apply a tensile force to the base film 2 having the coated layer by providing the base film 2 at a lower position than the other guide rolls 11 and 13. However, It is preferable that the method shown in Fig. 2 (b) is used because the coating layer on the side opposite to the side on which the coating layer is laminated can be used.

3, the base film 2 having a coated layer is supported by the five guide rolls 14, 15, 16, 17 and 18 in the drying zone, and the guide rolls 15, 16 and 17 The guide rolls 16 are provided at positions higher than the other guide rolls 14 and 18 and the center guide roll 16 is provided at a higher position than the guide rolls 15 and 17. [ By employing the method as shown in Fig. 3, the number of guide rolls is larger than that of the embodiment shown in Fig. 2 (b), and the distance between the guide rolls can be reduced. The substrate film 2 having the coating layer can be transported in a more stable state without causing any relaxation in the substrate film 2. Therefore, it is easy to make the maximum amplitude of the thickness in the width direction in the resin layer made of the polyvinyl alcohol-based resin smaller. From this viewpoint, the distance between the guide rolls is preferably 20 to 150 cm, more preferably 30 to 100 cm. If the distance between the guide rolls is more than 150 cm, the substrate film (2) having the coated layer tends to be easily relaxed, or the base film (2) having the coated layer may be stretched by applying a large tension to prevent relaxation .

In addition to the methods shown in Figs. 2 and 3, as a method of applying appropriate tension to a base film having a coating layer, a method of restricting the ends by disposing nip rollers only at the end portions of the base film before and after the guide roll, And the like. A method of restraining a base film having a coating layer by a suction force using a suction roll is also preferable.

The thickness of the resin layer made of the polyvinyl alcohol resin in the laminated film obtained through the above step (2-1) is preferably 2 to 10 mu m, more preferably 4 to 10 mu m. When the thickness of the resin layer made of polyvinyl alcohol resin is 2 to 10 占 퐉, it is preferable because the polarizing layer obtained in a subsequent step has good polarization performance and durability.

[Step (2-2)]

In the step (2-2), a base film having a coating layer is transported to a drying zone in a floating manner. By drying the coating layer, a resin layer made of polyvinyl alcohol resin can be formed. At this time, the dew point of the atmosphere in the drying zone is 50 DEG C or lower, preferably 47 DEG C or lower, more preferably 20 DEG C or lower. The ordinary dew point is 0 ° C or more. By setting the dew point to 50 占 폚 or less, the drying time can be shortened, and the distribution of the aqueous solution containing the polyvinyl alcohol resin can be further suppressed from becoming uneven on the base film.

It is also preferable that the coating layer is solidified at the time when it passes through the last drying zone in the step (2-2) to be a resin layer made of a polyvinyl alcohol-based resin. By completing the solidification of the coating layer in the step (2-2), when the laminated film is conveyed to a post-process, or when the laminated film is wound on a roll, the distribution of the aqueous solution containing the polyvinyl alcohol- It is possible to suppress unevenness on the film. If moisture is not felt by contacting the coating layer with a finger, solidification may be considered to be completed.

As shown in Fig. 4, a floating method is a method in which air is blown from nozzles 4 provided above and below a base film 2 having a coating layer, and a base film having a coating layer is floated in the air, And the substrate film having the layer is transported. The arrow 5 indicates the direction of the wind to be sprayed. In the step (2-2), the drying zone includes hot roll, drying furnace, and air blowing. Two or more drying zones may be installed in the transport path. Two or more kinds of drying zones may be provided. In this case, a combination of a drying furnace and air blowing can be mentioned.

Drying by blowing air is achieved by blowing air blown from nozzles provided above and below the base film having a coating layer as warm air. The drying temperature at the time of drying by air blowing is preferably from 50 to 150 캜, more preferably from 60 to 140 캜. By setting the drying temperature at 50 占 폚 or higher, the drying time can be shortened and the productivity can be improved. The drying temperature at the time of drying by air blowing means the temperature of the air sprayed onto the coating layer. The wind speed is preferably 0.5 to 20 m / s, more preferably 1.0 to 15 m / s. When the wind speed is 0.5 to 20 m / s, the fluctuation of the base film having the coated layer can be suppressed and the drying time can be shortened. Thus, the film thickness distribution in the width direction can be made more uniform, have. The drying time when drying by air blowing is preferably 30 to 1500 seconds, more preferably 180 to 1000 seconds, and most preferably 360 to 600 seconds. The drying time when drying by blowing air means the time when air is blown onto the film to be transported.

Drying by a drying furnace is achieved by conveying a base film having a coating layer by a floating method in a drying furnace. The atmospheric temperature in the drying furnace when dried by the drying furnace is preferably 40 to 130 캜, more preferably 50 to 120 캜. By setting the drying temperature at 40 占 폚 or higher, the drying time can be shortened and the productivity can be improved. The drying time for drying by a drying oven is preferably 30 to 1500 seconds, more preferably 180 to 1000 seconds, and still more preferably 360 to 600 seconds. The drying time when drying is performed by the drying furnace is the sum of the time during which the film to be transported is staying in the drying furnace.

The thickness of the resin layer made of the polyvinyl alcohol resin in the laminated film obtained through the above step (2-2) is 10 占 퐉 or less as described above. The thickness of the resin layer made of polyvinyl alcohol resin is preferably 2 m or more, and more preferably 4 m or more. When the thickness of the resin layer made of polyvinyl alcohol resin is 2 m or more, it is preferable because a polarizer layer having good polarization performance and durability can be obtained.

The laminated film of the present invention can be produced by the steps including the above-mentioned steps (1-1) and (2-1), or the steps including the steps (1-2) and (2-2). When the polarizing laminated film or the polarizing plate is produced from the laminated film of the present invention, the following process (3) and the process (4) or the process (3) to the process (6) . In the case of producing the laminated film of the present invention by the roll-to-roll method, the laminated film may be wound into a single roll at a stage after the step (2-1) or the step (2-2) It may be conveyed to a post-process as it is. The laminated film roll in which the laminated film of the present invention is wound on a roll has a uniform film thickness distribution in the width direction, so that the end of the laminated film roll is not easily tightened, and the subsequent steps (3) to Can be improved. Further, in the case where the sheet is conveyed to a post-process without being wound, the step of winding the sheet on the roll can be omitted, thereby improving the productivity.

In the laminated film of the present invention, a resin layer made of a polyvinyl alcohol-based resin may be formed on one side of the base film, but a resin layer made of a polyvinyl alcohol-based resin may be formed on both sides of the base film. As a method for forming a resin layer made of a polyvinyl alcohol resin on both sides of a base film, a resin layer is first formed on one surface of a base film, and then a resin layer is formed on the surface of the base film on which a resin layer is not formed. The step (1-1) and the step (2-1), or the step (1-2) and the step (2-2) may be carried out. In this specification, a laminated film in which a resin layer made of a polyvinyl alcohol resin is formed on one side of a base film is sometimes referred to as a laminate on one side, and a laminate film in which a resin layer made of a polyvinyl alcohol resin is formed on both sides of a base film The film may be referred to as a double-side laminated product. The double-side laminated product is advantageous from the viewpoint of productivity because a resin layer composed of two polyvinyl alcohol resins can be formed on one base film.

Step (3) A stretching process for obtaining a stretched laminated film by uniaxially stretching the laminated film

Step (4) Dyeing process for obtaining a polarizing laminated film having a polarizer layer and a base film by dyeing the oriented laminated film

(5) A bonding process for bonding a transparent protective film to a polarizer layer in a polarizing laminated film to obtain a multilayered film

Step (6) A peeling step of peeling the base film from the multilayer film to obtain a polarizer and a polarizing plate having a transparent protective film

[Step (3)]

In the step (3), a laminated film having a resin layer composed of a base film and a polyvinyl alcohol resin is uniaxially stretched to obtain a stretched laminated film. Preferably, the uniaxial stretching is performed so that the stretching magnification is more than 5 times and not more than 17 times. A more preferable stretching magnification is more than 5 times and not more than 8 times. If the stretching magnification is 5 times or less, the resin layer made of the polyvinyl alcohol resin is not sufficiently oriented, resulting in a problem that the degree of polarization of the polarizer layer is not sufficiently increased. On the other hand, when the stretching magnification exceeds 17 times, the laminated film tends to be broken at the time of stretching, and at the same time, the stretched laminated film becomes thin more than necessary, which may lower the workability and handling property in a subsequent step. The stretching treatment in the step (3) is not limited to the stretching in one stage but can be performed in multiple stages. In this case, the drawing step after the second step may be performed in the step (3), but may be performed simultaneously with the dyeing treatment or the crosslinking treatment in the step (4). When the stretching is performed in such a multi-stage, the stretching process is performed so that the front ends of the stretching process are combined so that the stretching ratio exceeds 5 times. In the case of performing the stretching in the step other than the step (3), the stretching magnification in the step (3) can be made more than 1 time and 3.5 times or less.

In the step (3), longitudinal stretching performed in the longitudinal direction of the laminated film and transverse stretching in the transverse direction can be adopted. When longitudinal stretching is adopted, a roll stretching method, a compression stretching method, or the like can be used as the method, and in the case of employing transverse stretching, a tenter method can be used as the method.

The stretching treatment can be carried out by both the wet stretching method and the dry stretching method, but it is preferable to use the dry stretching method in that the temperature at the time of stretching the laminated film can be selected in a wide range.

[Step (4)]

In the step (4), the resin layer of the stretched laminated film is dyed with a dichroic dye. As the dichroic dye, iodine or a dichroic organic dye is specifically used. Examples of the dichroic organic dyes include red BR, red LR, red R, pink LB, rubin BL, Borde GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, violet LB, B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Blue, Direct First Orange S, and First Black. These dichroic organic dyes are available on the market. The dichroic dye may be used alone, or two or more dichroic dyes may be used in combination.

Step (4) is carried out, for example, by immersing the stretched film in a solution (dyeing solution) containing the dichroic dye. As the dyeing solution, a solution prepared by dissolving the dichroic dye in a solvent can be used. As the solvent of the dyeing solution, generally water is used, but an organic solvent compatible with water may be further added. The concentration of the dichroic dye in the dyeing solution is preferably 0.01 to 10% by weight, more preferably 0.02 to 7% by weight, and particularly preferably 0.025 to 5% by weight.

When iodine is used as the dichroic dye, it is preferable to add iodide in order to further improve the dyeing efficiency. The iodide used for this purpose can be, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide and the like. When iodide is added, the proportion thereof is preferably 0.01 to 20% by weight in the dyeing solution. Among the iodides exemplified above, potassium iodide is preferably used. 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, more preferably 1: 7 to 1: 70.

The immersing time of the stretched laminated film in the dyeing solution is not particularly limited, but it is preferably in the range of 15 seconds to 15 minutes, more preferably 30 seconds to 3 minutes. The temperature of the dyeing solution is preferably in the range of 10 to 60 占 폚, and more preferably in the range of 20 to 40 占 폚.

In addition, although the dyeing treatment can be carried out before or during the stretching step, the step (3) is performed on the unstretched laminated film so that the dichromatic dye adsorbed to the polyvinyl alcohol resin can be favorably oriented It is preferable to perform the dyeing treatment. At this time, it is possible to simply dye only those drawn in advance at the target magnification, or to stretch them in advance at the low magnification so as to reach the desired magnification in total. Further, in the case of stretching even during the subsequent crosslinking treatment, the total stretching ratio at the stage where the dyeing treatment is completed can be set to be lower than the desired final stretching ratio. In this case, it may be appropriately adjusted so as to reach a desired magnification after the crosslinking treatment.

In the step (4), the crosslinking treatment can be carried out subsequently to dyeing. The crosslinking treatment can be performed by, for example, a method of immersing the drawn film in a solution (crosslinking solution) containing a crosslinking agent. As the crosslinking agent, conventionally known materials can be used. Examples thereof include boron compounds such as boric acid and borax, and glyoxal and glutaraldehyde. One type of crosslinking agent may be used alone, or two or more types of crosslinking agents may be used in combination.

As the crosslinking solution, a solution in which a crosslinking agent is dissolved in a solvent can be used. As the solvent, for example, water may be used, but it may further include an organic solvent compatible with water. The concentration of the crosslinking agent in the crosslinking solution is not limited thereto, but is preferably in the range of 1 to 20% by weight, and more preferably in the range of 6 to 15% by weight.

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

The immersing time of the stretched laminated film in the crosslinking solution is preferably 15 seconds to 20 minutes, more preferably 30 seconds to 15 minutes. The temperature of the crosslinking solution is preferably in the range of 10 to 90 占 폚.

The crosslinking treatment may be carried out simultaneously with the dyeing treatment by blending the crosslinking agent into the dyeing solution. In this case, the film stretched in advance at the target magnification may be dipped in a dyeing solution containing a cross-linking agent. In this case, only dyeing and cross-linking may be performed substantially, or may be simultaneously stretched in a dyeing solution containing a cross-linking agent. In step (3), the stretched laminated film stretched in advance at a low magnification may be stretched again in a dyeing solution containing a crosslinking agent to reach a desired magnification in a total amount. Of course, it is also possible to perform the stretching treatment, the dyeing treatment and the crosslinking treatment in this order. In this case, further stretching treatment may be performed at the stage of dyeing treatment and / or crosslinking treatment. The point is that at the stage where the crosslinking treatment is finished, the total draw ratio may be set to a desired value.

Finally, it is preferable to carry out a washing step and a drying step. In the washing step, a water washing treatment can be employed. The water washing treatment is usually carried out by immersing the drawn film in pure water such as ion-exchanged water or distilled water. The temperature of water washing is usually in the range of 3 to 50 캜, preferably 4 to 20 캜. The immersion time for water is usually from 2 to 300 seconds, preferably from 3 to 240 seconds.

The washing step may be a combination of a washing treatment with a iodide solution and a water washing treatment. In these washing steps, an aqueous solution in which a liquid alcohol such as methanol, ethanol, propanol, isopropanol or butanol is appropriately blended may also be used. The iodide contained in the iodide solution includes potassium iodide, and its concentration is usually 0.5 to 10% by weight.

After the cleaning step, it is preferable to carry out the drying step. In the drying step, any appropriate method (for example, natural drying, air blow drying, heat drying, etc.) may be employed. For example, in the case of heat drying, the drying temperature is usually 20 to 95 占 폚, and the drying time is usually about 1 to 15 minutes. By the above-described step (4), the resin layer has a function as a polarizer. In the present specification, a laminate having a polarizer layer on a base film and a resin layer having a function as a polarizer is referred to as a polarizer layer, is referred to as a polarizing laminated film.

[Step (5)]

In the step (5), a transparent protective film is bonded to a surface of the polarizer layer opposite to the surface on the base film side to obtain a multilayer film. As the bonding of the protective film, a pressure-sensitive adhesive or an adhesive can be used.

[Protection film]

The protective film may be a simple protective film having no optical function or a protective film having optical functions such as a retardation film and a brightness enhancement film. The material constituting the protective film is not particularly limited, and examples thereof include cyclic polyolefin resin, cellulose acetate resin such as triacetyl cellulose and diacetyl cellulose, poly A polyester resin, an ester-based resin, a polycarbonate-based resin, an acrylic resin, and a polypropylene-based resin.

Examples of the cyclic polyolefin resin include commercially available products such as TOPAS (manufactured by Topas Advanced Polymers GmbH), ATON (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (manufactured by Nippon Zeon Co., Ltd.) ZEONEX (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), APEL (registered trademark) (manufactured by Mitsui Chemicals, Inc.), and the like can be suitably used. When a film of such an annular polyolefin-based resin is produced, a known method such as a solvent casting method or a melt extrusion method is suitably used. In addition, a cyclic polyolefin-based polymer having a further retardation imparted thereto in some cases, such as Essen (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), ZeonoAFIL (registered trademark) (manufactured by Nippon Zeon Co., A commercially available resin film may be used.

The cyclic polyolefin-based resin film may be uniaxially or biaxially-stretched. By stretching, an arbitrary retardation value can be imparted to the cyclic polyolefin-based resin film. The stretching is usually carried out continuously while unwinding the film roll, and is stretched in the heating roll in the direction of the roll, in the direction orthogonal to the progressing direction of the roll, or both. The temperature of the heating furnace is usually in the range from the vicinity of the glass transition temperature of the cyclic polyolefin-based resin to the glass transition temperature + 100 ° C. The magnification of the stretching is usually 1.1 to 6 times, preferably 1.1 to 3.5 times in one direction.

The surface of the annular polyolefin-based resin film generally has poor surface activity, so that the surface to be adhered to the polarizer layer is subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, flame treatment or saponification treatment desirable. Of these, plasma treatment and corona treatment that can be performed relatively easily are suitable.

Examples of the cellulose acetate based resin film include commercially available products such as Fujitac (registered trademark) TD80 (manufactured by Fuji Film), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film), Fujitac (registered trademark) TD80UZ (Manufactured by Konica Minolta Co., Ltd.), KC4UY (manufactured by Konica Minolta Co., Ltd.), and the like can be suitably used.

A liquid crystal layer or the like may be formed on the surface of the cellulose acetate-based resin film in order to improve the viewing angle characteristics. In order to impart a retardation, an elongated acetic acid cellulose based resin film may also be used. The cellulose acetate-based resin film is usually subjected to saponification treatment in order to improve adhesion with the polarizer layer. The saponification treatment is carried out by immersing the film in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.

On the surface of the protective film as described above, an optical layer such as a hard coat layer, an antiglare layer, and an antireflection layer may be formed. Methods for forming these optical layers on the surface of the protective film are not particularly limited, and known methods can be used.

The thickness of the protective film is preferably as thin as possible from the viewpoint of thinning, and is preferably 90 占 퐉 or less, more preferably 50 占 퐉 or less. On the other hand, if it is too thin, the strength may be lowered and the workability may be impaired.

[Pressure sensitive adhesive layer]

The pressure-sensitive adhesive is usually formed from a composition obtained by using an acrylic resin, a styrene resin, a silicone resin, or the like as a base polymer and adding thereto a crosslinking agent such as an isocyanate compound, an epoxy compound, or an aziridine compound. It is also possible to use a pressure-sensitive adhesive layer containing fine particles and exhibiting light scattering properties.

It is preferable that the pressure-sensitive adhesive layer has a thickness of 1 to 40 m, but it is preferable that the pressure-sensitive adhesive layer is thinly coated within a range that does not impair processing characteristics such as workability and durability, and more preferably 3 to 25 m . When the thickness is 3 to 25 占 퐉, it has good processability and is also suitable for suppressing the dimensional change of the polarizing plate. When the thickness of the pressure-sensitive adhesive layer is less than 1 占 퐉, the pressure-sensitive adhesive property is deteriorated. On the other hand, when the thickness exceeds 40 占 퐉, problems such as the pressure-

The method of forming the pressure-sensitive adhesive layer on the protective film or the polarizer layer is not particularly limited, and a solution containing each component including the above-mentioned base polymer is applied to the protective film surface or the polarizer layer surface and dried to form a pressure- After that, a separator or another type of film may be bonded to the pressure-sensitive adhesive layer, or a pressure-sensitive adhesive layer may be formed on the separator and then laminated on the protective film surface or the polarizer layer surface. When the pressure-sensitive adhesive layer is formed on the protective film or polarizer layer surface, adhesion processing, for example, corona treatment, or the like may be performed on one side or both sides of the protective film or the polarizer layer side or the pressure-

[Adhesive layer]

As the adhesive, for example, an aqueous adhesive composed of a polyvinyl alcohol resin aqueous solution, an aqueous two-component type urethane emulsion adhesive, or the like can be used. Among them, a polyvinyl alcohol resin aqueous solution is suitably used. The polyvinyl alcohol resin used as the adhesive includes a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate, a vinyl alcohol homopolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith, Based copolymers, and further modified polyvinyl alcohol polymers obtained by partially modifying the hydroxyl groups of these polymers. A polyvalent aldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound and the like may be added to the water-based adhesive as an additive. When such an aqueous adhesive is used, the adhesive layer obtained next is usually much thinner than 1 mu m, and even if a cross section is observed with an ordinary optical microscope, the adhesive layer is practically not observed.

The method of bonding the film using the water-based adhesive is not particularly limited, and a method in which an adhesive is uniformly applied or introduced onto the surface of the film, the other film is overlaid on the coated surface, have. Usually, the adhesive is applied at a temperature of 15 to 40 캜 after its preparation, and the bonding temperature is usually in the range of 15 to 30 캜.

When an aqueous adhesive is used, the film is bonded and then dried to remove water contained in the aqueous adhesive. The temperature of the drying furnace is preferably in the range of 30 to 90 占 폚. When the drying temperature is less than 30 ° C, the adhesive surface tends to be easily peeled off. On the other hand, when the drying temperature is 90 DEG C or higher, there is a fear that the optical performance of the polarizer or the like is deteriorated by heat. The drying time may be about 10 to 1000 seconds.

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

As the non-aqueous adhesive, a photo-curing adhesive may be used. Examples of the photo-curable adhesive include a mixture of a photo-curable epoxy resin and a photo cationic polymerization initiator.

When a film is bonded using a photo-curable adhesive, conventionally known methods can be employed. For example, a flexible method, a Meyer bar coat method, a gravure coat method, a comma coater method, a doctor blade method, a die coat method, A method in which an adhesive is applied to the adhesion surface of the film by a coating method, a spraying method, or the like, and the two films are overlapped. The flexible method is a method in which an adhesive is caused to flow on the surface of the two films while the two films, which are the object to be coated, are moved in a substantially vertical direction, a substantially horizontal direction, or an inclined direction therebetween.

An adhesive is applied to the surface of the film, and then the film is sandwiched by a nip roll or the like to be bonded. Further, a method of pressing the laminate with a roll or the like and uniformly widening it may also be suitably used. In this case, the material of the roll may be metal, rubber, or the like. It is also preferable to adopt a method of passing the laminate between rolls and rolls, and then expanding it by pressing. In this case, these rolls may be made of the same material or different materials. The adhesive layer after bonding using a nip roll or the like is preferably such that the thickness before drying or curing is 0.01 탆 or more and 5 탆 or less.

The adhesive surface of the film may be appropriately subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, flame treatment, and saponification treatment, in order to improve the adhesiveness. The saponification treatment is carried out by immersing the film in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.

When a photo-curable resin is used as the adhesive, the photo-curable adhesive is cured by laminating the films and then irradiating with active energy rays. A light source of an 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, a low energy mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, A wave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The light irradiation intensity for the photo-curable adhesive is appropriately determined according to the composition of the photo-curable adhesive and is not particularly limited, but it is preferable that the irradiation intensity in the wavelength range effective for activating the polymerization initiator is 0.1 to 6000 mW / cm ² Do. By appropriately selecting the irradiation intensity in this range, it is possible to suppress the possibility that the reaction time does not become too long, the heat radiated from the light source, and the yellowing of the adhesive or deterioration of the polarizing plate due to heat generation at the time of curing of the photo- have. The light irradiation time for the photo-curable adhesive is determined according to the photo-curable adhesive to be cured, and is not particularly limited. However, the cumulative light quantity expressed by the product of the irradiation intensity and the irradiation time is 10 to 10000 mJ / cm ² . By appropriately selecting the integrated light quantity for the photo-curable adhesive in this range, it is possible to generate a sufficient amount of active species derived from the polymerization initiator to more surely advance the curing reaction, and the irradiation time is not excessively long, have. The thickness of the adhesive layer after curing is usually about 0.001 to 5 mu m, preferably 0.01 mu m or more, and more preferably 2 mu m or less.

When the photo-curing adhesive between the polarizer layer and the protective film is cured by irradiation of an active energy ray, various functions of the polarizing plate, such as the polarization degree, transmittance and hue of the polarizer layer, and transparency of the protective film are not deteriorated It is preferable to perform the curing under the conditions.

[Step (6)]

In the step (6), the base film is peeled from a multilayer film having a protective film, a polarizer layer and a base film in this order. The method of peeling off the base film is not particularly limited and can be peeled off in the same manner as the peeling film peeling process from the pressure-sensitive adhesive layer employed in a usual polarizing plate with a pressure-sensitive adhesive. After the step (5) of bonding the protective film, the base film may be immediately peeled off, and the base film may be peeled off thereon after peeling off the film in a roll form. In this manner, a polarizing plate having a protective film and a polarizer layer can be produced.

A polarizing plate having a protective film, a polarizer layer and a protective film in this order may also be obtained by bonding a protective film on the polarizing layer. As the protective film to be newly bonded, there can be mentioned the same protective film as the above-mentioned protective film. As for the bonding of the protective film, a pressure-sensitive adhesive or an adhesive may be used as described above. Further, another optical film may be bonded onto the protective film. Examples of other optical films include a brightness enhancement film, an antiglare function-imparting film having a concavo-convex shape on the surface, a surface antireflection function imparting film, a reflection film having a reflection function on the surface, a transflective film , And a viewing angle compensation film. Other optical films and protective films can be bonded by the adhesive and the adhesive.

It is preferable that the polarizing plate of the present invention has a pressure-sensitive adhesive layer for bonding the polarizing plate to the liquid crystal cell on the outside of the transparent resin film (that is, the surface opposite to the side where the polarizing film is laminated). As the pressure sensitive adhesive for forming the pressure sensitive adhesive layer for bonding the polarizing plate to the liquid crystal cell, the pressure sensitive adhesive may be used. Among them, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. It is preferable that the pressure-sensitive adhesive layer is protected by a separator until the polarizing plate is bonded to the liquid crystal cell.

[Step (7)]

Step (7) is a chip-cutting step of cutting the elongated polarizing plate to a predetermined size. The polarizing plate produced by the above process is suitable as a member constituting a display device such as a liquid crystal display device. When a polarizing plate is produced by the roll-to-roll method, a long polarizing plate may be cut into a mica of a predetermined size and introduced into a display device.

Examples of the method of cutting a long polarizing plate into a wax include a method of cutting with a cutting tool having a sharp blade, a method of cutting by irradiating a laser beam, and a combination of both methods.

The cutting tool having a sharp blade may be a cutter usually used in the field of optical films, for example, a press-type cutter, a dicing-type cutter, and further, a fixed round blade or a rotating round blade. Examples of the laser light include a CO ₂ laser, a YAG laser, a semiconductor laser, and the like. Among them, a CO ₂ laser or a semiconductor laser is preferable. The laser light may be continuous light or pulse light. In the above-described laser irradiation, the output and the velocity are not limited, and it may be cut by one irradiation or may be cut by a plurality of irradiation. The output of the laser irradiation is usually from 10 W to 800 W, preferably from 100 W to 350 W when cutting with one irradiation, and preferably from 50 W to 200 W when cutting with two irradiation Do.

As a method of cutting by a cutting tool having a sharp blade and cutting by irradiating laser light, the polarizing plate is cut by laser light up to the middle in the thickness direction, and the rest is cut by a cutting tool having a sharp blade And a method of cutting. In this embodiment, it is preferable to cut off the laser light immediately before or after the layer where the absorption rate of the laser light is 5% or less from the surface layer, and cut the remaining portion with a cutting tool having a sharp blade.

The speed at which the polarizing plate is cut depends on the thickness of the polarizing plate to be cut. However, if the thickness of the polarizing plate is in the range of 70 to 500 占 퐉, the speed is 1 m / min or more, preferably 5 to 60 m / min.

After cutting the elongated polarizing plate into a sheet of wool, it is preferable that the peripheries of the polarizing plates are cut. As a method for cutting the side surface, for example, a method of cutting a peripheral edge of a polarizing plate with a rotary blade as disclosed in Japanese Patent Application Laid-Open No. 2001-54845 or a method disclosed in Japanese Patent Application Laid-Open No. 2003-220512 A method of continuously cutting the outer circumferential end of the polarizing plate by the fly-cut method as described above, and the like are preferably adopted. It is presumed that the pressure sensitive adhesive component covers the side circumferential surface uniformly by cutting the side surface in this manner, but it is advantageous to avoid exposure of the polarizer layer to the outside.

The shape of the polarizing plate obtained through the above step (7) is not particularly limited, but is preferably rectangular. When the shape of the polarizing plate is rectangular, the length of the long side is, for example, 5 cm or more, and the length of the short side is, for example, 3 cm or more. The upper limit is not particularly limited, but the length of the long side and short side is usually 5 m or less.

Example

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples at all.

[Assessment Methods]

≪ Maximum amplitude of resin layer thickness in the width direction >

The full-width direction width of the laminated film was scanned by an interference film thickness meter (manufactured by F20 Film Matrix Co., Ltd.) to measure the film thickness profile in the width direction. The layer configuration of the measured sample is a resin layer made of a base film / primer layer / polyvinyl alcohol resin. The measurement was performed while moving the sample to the automatic stage so that the measurement interval was 2 mm or less. The magnitude of the difference between the largest peak and the largest peak in the profile of the film thickness in the width direction thus obtained was taken as the maximum amplitude.

≪ Period intensity of film thickness distribution >

The thickness profile in the width direction obtained as described above was subjected to fast Fourier transform by Fourier analysis introduced in Microsoft Excel 2010. [ The value of the maximum amplitude in the range of 30 to 70 mm in the period of the thus obtained wave spectrum was defined as the period intensity of the film thickness distribution. Specifically, the number of data A used in the calculation at this time is smaller than the number of data (B) of the obtained thickness profile in the width direction, and is a power of 2 that is closest to B. The amplitude value is represented by 2C / A when the absolute value of the result of the Fourier transform is C, and the period is represented by Ln / N when the width position of the Nth data is Ln. The amplitude and period of each of the A pieces of data used in the calculation were obtained, and the maximum amplitude in the region where the period was 30 to 70 mm was obtained.

[Example 1]

≪ Fabrication of laminated film &

(1)

As the base film, an unoriented polypropylene (PP) film (melting point: 163 占 폚) having a thickness of 90 占 퐉 was prepared. The tensile modulus of the base film at 80 캜 was 205 MPa.

(2) Preparation of coating liquid for forming primer layer

A polyvinyl alcohol aqueous solution having a concentration of 3% by weight was prepared by dissolving polyvinyl alcohol powder ("Z-200" manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization: 1100, average saponification degree: 99.5 mol%) in hot water at 95 ° C. To the resulting aqueous solution was added 1 part by weight of a crosslinking agent ("Sumireze Resin (registered trademark) 650" manufactured by Daoka Chemical Co., Ltd.) to 2 parts by weight of polyvinyl alcohol powder to obtain a coating solution for forming a primer layer.

(3) Preparation of aqueous solution containing polyvinyl alcohol resin

Polyvinyl alcohol powder ("PVA 124" manufactured by Kuraray Co., Ltd., average degree of polymerization: 2400, average degree of saponification: 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol resin Was prepared.

(4) Processes (1), (2)

· One side laminates

A corona treatment was performed on one surface of the base film while continuously conveying the base film, and then the coating solution for the primer layer was continuously coated on the corona-treated surface by a microgravure coater. And then dried at 60 DEG C for 3 minutes to form a primer layer having a thickness of 0.2 mu m. Subsequently, while the film was being conveyed, an aqueous solution containing the polyvinyl alcohol resin was continuously coated on the primer layer by a lip coater.

And dried in an oven having eight guide rolls at 80 DEG C for 10 minutes to form a resin layer made of a polyvinyl alcohol resin having a thickness of 9.5 mu m on the primer layer to obtain a laminated film. At this time, the dew point in the drying furnace was 27 DEG C, and it was judged that the resin layer was solidified because the moisture was not felt when it was checked by touching the coated layer with the finger before the application to the 8th roll.

And a film thickness profile in the width direction was obtained at a measurement interval of 0.85 mm. The maximum amplitude of the film thickness in the width direction was 0.6 mu m. The periodic intensity of the film thickness distribution at this time was 0.06.

· Double-sided laminated products

The same treatment was applied to the surface of the base film opposite to the surface on which the resin layer was formed to form a resin layer composed of a primer layer having a thickness of 0.2 탆 and a polyvinyl alcohol resin having a thickness of 9 탆 To prepare a laminated film of double-side laminated products. The dew point in the drying oven was 28 ° C.

A film thickness profile in the width direction was obtained at a measurement interval of 0.90 mm. The maximum amplitude of the film thickness in the width direction was 0.2 탆. The periodic intensity of the film thickness distribution at this time was 0.03.

(5) Step (3)

While the laminated film obtained in the above (4) was continuously conveyed, the film was stretched 2.5 times at a stretching temperature of 140 占 폚 in a longitudinal direction (film conveying direction) by a stretching method between nip rolls, (Total draw ratio: 5.8 times) to obtain a stretched laminated film. The thickness of the resin layer made of the polyvinyl alcohol resin in the stretched laminated film was 5.2 mu m and 5.3 mu m, respectively.

≪ Preparation of polarizing laminated film >

(6) Step (4)

The stretched laminated film was immersed in a dyeing solution containing iodine and potassium iodide at a temperature of 30 DEG C for a retention time of about 150 seconds to dye the resin layer made of a polyvinyl alcohol resin, The excess dyeing solution was washed away. Subsequently, the substrate was immersed in a crosslinked solution at 76 DEG C containing boric acid and potassium iodide so that the residence time would be 600 seconds, and crosslinking treatment was carried out. Thereafter, the film was washed with pure water at 10 캜 for 4 seconds and dried at 80 캜 for 300 seconds to obtain a polarizing laminated film.

<Production of polarizing plate>

(7) Steps (5), (6)

A polyvinyl alcohol aqueous solution having a concentration of 3% by weight was prepared by dissolving polyvinyl alcohol powder ("KL-318" manufactured by Kuraray Co., Ltd., average degree of polymerization: 1800) in hot water at 95 ° C. 1 part by weight of a cross-linking agent (&quot; Sumireze Resin (registered trademark) 650 &quot; manufactured by Daoka Chemical Co., Ltd.) was mixed with 2 parts by weight of polyvinyl alcohol powder to obtain an adhesive solution.

Next, the above-mentioned adhesive solution was coated on the polarizing layer of both sides of the polarizing laminated film, and then a protective film (triacetylcellulose (TAC) transparent protective film (manufactured by Konica Minolta Opto Co., Ltd., KC4UY ", thickness: 40 μm) was bonded on the polarizing layer and passed between a pair of bonding rolls to obtain a multi-layer film comprising TAC / polarizer / primer layer / base film / primer layer / polarizer / TAC. The multilayer film was peeled off between the base film and the primer layer to form a TAC / polarizer / primer layer / base film, primer layer / polarizer / TAC. Subsequently, the base film was peeled off to obtain a polarizing plate in which a protective film was laminated on a polarizer layer made of a TAC / polarizer / primer layer with an adhesive layer interposed therebetween. No problem of breakage occurred in the peeling process.

<Confirmation of stripe unevenness>

Each of the polarizing plates was cut to a full width of 150 mm in the direction of the absorption axis and at a right angle to the absorption axis. The polarizing plate was placed in an oven at 105 ° C for 30 minutes and observed as another polarizing plate and cross- No noticeable irregularities were observed on the polarizing plate.

[Example 2]

In the same manner as in Example 1 except that the number of the guide rolls in the drying zone of the aqueous solution containing the polyvinyl alcohol resin was set to 3 and the drying was carried out at 90 DEG C for 5 minutes in the single- Thereby forming a resin layer made of a polyvinyl alcohol-based resin having a thickness of 9.6 占 퐉 on the primer layer. The dew point in the drying furnace was 26 占 폚, and immediately before the third roll, when it was confirmed that the coating layer was contacted with the fingers, it was judged that the resin layer was solid because moisture was not felt.

A film thickness profile in the width direction was obtained at a measurement interval of 0.83 mm. The maximum amplitude of the film thickness in the width direction was 0.6 mu m. The periodic intensity of the film thickness distribution at this time was 0.03.

A polarizing plate was produced in the same manner as in Example 1 except that it was in a one-side laminated state, no particular problem occurred, and no noticeable stripe unevenness was observed.

[Example 3]

The same operation as in Example 2 was carried out except that the number of guide rolls in the drying zone of the aqueous solution containing the polyvinyl alcohol resin was set to one and the drying was carried out at 90 DEG C for 5 minutes in the single- Thereby forming a resin layer made of a polyvinyl alcohol-based resin having a thickness of 9.4 占 퐉 on the primer layer. The dew point in the drying furnace was 27 DEG C, and when it was confirmed by touching the coated layer with a finger in front of the outlet of the drying furnace, moisture was not felt, and it was judged that the resin layer was solidified.

A film thickness profile in the width direction was obtained at a measurement interval of 0.86 mm. The maximum amplitude of the film thickness in the width direction was 0.7 mu m. The periodic intensity of the film thickness distribution at this time was 0.06.

A polarizing plate was produced in the same manner as in Example 1 except that it was in a one-side laminated state, no particular problem occurred, and no noticeable stripe unevenness was observed.

[Example 4]

In the same manner as in Example 3, except that the drying zone of the aqueous solution containing the polyvinyl alcohol-based resin layer was set as the floating system in Example 3 and dried at 80 캜 for 20 minutes by a drying oven and air blowing, A resin layer made of a polyvinyl alcohol-based resin having a thickness of 9.9 mu m was formed on the layer. The dew point in the drying oven was 45 캜.

The film thickness profile in the width direction was obtained at a measurement interval of 0.78 mm. The maximum amplitude of the film thickness in the width direction was 1.2 mu m. The periodic intensity of the film thickness distribution at this time was 0.07.

A polarizing plate was produced in the same manner as in Example 2, however, no problem occurred in particular, and no noticeable stripe unevenness was observed.

[Example 5]

A resin layer made of a polyvinyl alcohol resin having a thickness of 9.1 탆 was formed on the primer layer in the same manner as in Example 4 except that the dew point in the drying furnace was changed to 20 캜 in Example 4.

The film thickness profile in the width direction was obtained at a measurement interval of 0.78 mm. The maximum amplitude of the film thickness in the width direction was 0.9 mu m. The periodic intensity of the film thickness distribution at this time was 0.07.

A polarizing plate was produced in the same manner as in Example 4, however, no particular problem occurred, and no noticeable unevenness in stripe pattern was observed.

[Comparative Example 1]

A resin layer made of a polyvinyl alcohol resin was formed on the primer layer in the same manner as in Example 3 except that the thickness of the resin layer made of polyvinyl alcohol resin was 11.9 탆.

A film thickness profile in the width direction was obtained at a measurement interval of 0.83 mm. The maximum amplitude of the film thickness in the width direction was 2.45 mu m. The periodic intensity of the film thickness distribution at this time was 0.10.

A polarizing plate was produced in the same manner as in Example 3, and no particular problem occurred. However, when the unevenness of the stripe pattern was confirmed, a strong stripe pattern was confirmed.

[Comparative Example 2]

When a base film having an elastic modulus at 80 占 폚 of 100 MPa was used, shrinkage was very large and wrinkles were generated at the time of forming the primer layer.

The laminated film of the present invention is useful because it can provide a polarizing plate without optical striped unevenness.

1, 11 to 18: guide roll
2: base film having a coating layer
3: Arrow
4: Nozzle
5: Arrow

Claims (8)

A laminated film on which a resin layer made of a polyvinyl alcohol resin is formed on a long base film,
And the maximum amplitude of the thickness in the width direction of the resin layer is not more than 2.0 mu m. The laminated film according to claim 1, wherein the periodic intensity of the film thickness distribution in the width direction of the resin layer is 0.09 or less. The laminated film according to claim 1 or 2, wherein an average value of the thickness in the width direction of the resin layer is 10 m or less. The method for producing a laminated film according to any one of claims 1 to 3, comprising the following steps (1-1) and (2-1):
Process (1-1) A coating process for obtaining a base film having a coating layer by coating an aqueous solution containing a polyvinyl alcohol resin on a base film to form a coating layer,
(2-1) A substrate film having a coating layer is conveyed to a drying zone. In the drying zone, while the substrate film having a coating layer is supported by at least one guide roll, the coating layer is dried to form a polyvinyl alcohol resin , And a laminated film is obtained. The method for producing a laminated film according to any one of claims 1 to 3, comprising the following steps (1-2) and (2-2):
(1-2) A coating process for obtaining a base film having a coating layer by coating an aqueous solution containing a polyvinyl alcohol resin on a base film to form a coating layer,
Step (2-2) A base film having a coating layer is conveyed to a drying zone in a floating manner to dry the coating layer to form a resin layer made of a polyvinyl alcohol resin having a thickness of 10 占 퐉 or less, As a drying step to be obtained, a drying step in which the dew point of the atmosphere in the drying zone is 50 DEG C or lower. A method for producing a polarizing laminated film comprising the following steps (3) and (4):
(3) A stretching process for obtaining a stretched laminated film by uniaxially stretching the laminated film according to any one of claims 1 to 5,
(4) A dyeing process for dyeing a stretched laminated film to obtain a polarizing laminated film having a polarizer layer and a base film. A method for producing a polarizing plate comprising the following steps (3) to (6):
(3) A stretching process for obtaining a stretched laminated film by uniaxially stretching the laminated film according to any one of claims 1 to 5,
(4) dyeing a stretched laminated film to obtain a polarizing laminated film having a polarizer layer and a base film,
Step (5) A bonding step of bonding a transparent protective film to the polarizer layer in the polarizing laminated film to obtain a multilayered film,
(6) A peeling process for peeling a base film from a multilayer film to obtain a polarizer having a polarizer and a transparent protective film. A process for producing a single sheet of a polarizing plate comprising the following step (7):
(7) A cutting step of cutting each of the polarizing plates described in (7) into a rectangular shape to obtain each of the polarizing plates.

Images