JP2016224233A - Production method of laminate film, and laminate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a laminate film by which sagging in an end part in a width direction of a laminate film can be decreased even when the film is stored as wound on a shaft.SOLUTION: The production method of a laminate film includes: an application step of applying a polyvinyl alcohol resin solution on at least one surface of a long base film; and a drying step of drying the applied solution while conveying the base film in a longitudinal direction to obtain a laminate film having the base film and a resin layer. In the drying step, a tension of 45 N or more per 1 m length in a width direction of the base film is applied in the longitudinal direction on the base film.SELECTED DRAWING: Figure 1

Description

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

  Conventionally, a polarizer comprising a step of coating a substrate film with a polyvinyl alcohol resin solution and drying to form a laminated film having a resin layer and a substrate film, and stretching and dyeing the laminated film. Manufacturing methods are known.

JP 2014-52647 A WO2014 / 136985 WO2013 / 146644

  In such a method for producing a polarizer, a laminated film before stretching and dyeing, a laminated film subjected to either stretching or dyeing, and a laminated film after stretching and dyeing are wound around a shaft temporarily as a roll. Often stored in. However, in the conventional method, when the laminated film is unwound from the stored roll, there is a case where slack occurs at the end portion in the width direction of the laminated film.

  The present invention has been made in view of the above problems, and provides a method for producing a laminated film or the like that can reduce the occurrence of slack at the end in the width direction of the laminated film even when wound around a shaft and stored. With the goal.

  As a result of intensive studies by the present inventors, the following facts have been found. The resin layer obtained by drying the resin solution on the base film while transporting the base film in the longitudinal direction tends to have a non-uniform thickness in which the end in the width direction is thicker than the center in the width direction. There is. When a laminated film having such a resin layer is wound around a shaft and stored as a roll, a tightening force is selectively applied to a relatively thick width direction end portion, and the width direction end portion extends. And if a laminated | multilayer film is unwound from a roll after storage, the width direction edge part will sag. Furthermore, the present inventors applied an appropriate tension to the base film transported in the longitudinal direction in the drying step of the resin solution in the longitudinal direction, and the width direction end portion in the resin layer obtained after drying is compared with the central portion. The present invention has been conceived by finding that the thickness is suppressed and the slackness after winding and storage is suppressed.

  The method for producing a laminated film according to the present invention includes a coating step of coating a solution of a polyvinyl alcohol resin on at least one surface of a long base film, and while transporting the base film in the longitudinal direction. A drying step of drying the coated solution to obtain a laminated film having the base film and the resin layer. And in the said drying process, the tension | tensile_strength of 45 N or more is given with respect to the length of the width direction of the said base film in the said longitudinal direction with respect to the said base film.

  According to the present invention, since an appropriate tension is applied to the base film in the longitudinal direction in the drying step, it is suppressed that the end in the width direction of the resin layer is thicker than the center, and the obtained film is pivoted. When the film is wound around the film, it is possible to prevent the film edge from being slackened.

  Moreover, the manufacturing method of the other laminated film which concerns on this invention is a coating process which coats the solution of a polyvinyl alcohol-type resin to the surface of at least one of a elongate base film, and the said base film is a longitudinal direction. A drying step of drying the solution coated while being conveyed to obtain a laminated film having the base film and the resin layer. And in the said drying process, tension | tensile_strength is given to the said longitudinal direction so that the dimensional change rate of the said longitudinal direction of the said base film before and behind the said drying process may exceed 0%.

  According to the present invention, since a tension is applied so that the base film undergoes plastic deformation in the drying step, it is suppressed that the end portion in the width direction of the resin layer is thicker than the central portion, and the obtained film It is possible to suppress the occurrence of slack in the film end when the wire is wound around the shaft.

  Here, the method may further include a winding step of winding the laminated film around an axis to obtain a roll of the laminated film.

  The manufacturing method of the light-polarizing laminated film according to the present invention includes a step of obtaining a laminated film by the method for producing a laminated film described above, and a polarizing property having the base film and the polarizer layer by stretching and dyeing the laminated film. Obtaining a laminated film.

  The said method can further be equipped with the winding-up process which winds the said polarizing laminated film on an axis | shaft, and obtains the roll of the said polarizing laminated film.

  The manufacturing method of the polarizing plate which concerns on this invention is a process which manufactures a light-polarizing laminated film with the manufacturing method of the above-mentioned light-polarizing laminated film, A protective film is put on the said polarizer layer of the said light-polarizing laminated film via an adhesive agent. The process of bonding and the process of peeling the said base film from the said polarizer layer and obtaining a polarizing plate are provided in this order.

  Here, the method may further include a winding step of winding the polarizing plate around an axis to obtain a roll of the polarizing plate.

The laminated film according to the present invention includes a long base film and a polyvinyl alcohol-based resin layer provided on at least one surface of the base film. And when the said polyvinyl alcohol-type resin layer is equally divided into nine area | regions in the direction orthogonal to the longitudinal direction of the said base film, the average film thickness of the center area | region of said nine area | regions is set to Dc, and outermost The following formula is satisfied when the larger difference between Dc and the average film thickness of each of the two regions is De.
De-Dc ≦ 0.4 μm

The stretched laminated film according to the present invention includes a long base film and a stretched polyvinyl alcohol-based resin layer provided on one surface of the base film. And when the base film and the stretched polyvinyl alcohol-based resin layer are equally divided into nine regions in a direction orthogonal to the longitudinal direction of the base film, an average of the central region of the nine regions When the film thickness is Dc and the average film thickness of each of the outermost two regions is set to be the larger difference from Dc, the following equation is satisfied.
De-Dc ≦ 1.6 μm

Another stretched laminated film according to the present invention includes a long base film and a pair of stretched polyvinyl alcohol-based resin layers provided on both surfaces of the base film. And when the base film and the pair of stretched polyvinyl alcohol-based resin layers are equally divided into nine regions in a direction orthogonal to the longitudinal direction of the base film, the center of the nine regions When the average film thickness of the region is Dc and the average film thickness of each of the two outermost regions is set to De which has a larger difference from Dc, the following equation is satisfied.
De-Dc ≦ 2.0 μm

The polarizing laminate film according to the present invention includes a long base film and a polarizer layer provided on one surface of the base film. And when the said base film and the said polarizer layer are equally divided into nine area | regions in the direction orthogonal to the longitudinal direction of the said base film, the average film thickness of the center area | region of said nine area | regions is set to Dc. The following equation is satisfied when De is the larger difference between Dc and the average film thickness of each of the two outermost regions.
De-Dc ≦ 1.6 μm

The light-polarizing laminated film according to the present invention includes a long base film and a pair of polarizer layers provided on both surfaces of the base film. And when the base film and the pair of polarizer layers are equally divided into nine regions in the direction orthogonal to the longitudinal direction of the base film, the average film thickness of the central region of the nine regions is The following equation is satisfied when Dc is set to De and the difference between Dc and the average film thickness of each of the outermost two regions is larger.
De-Dc ≦ 2.0 μm

  ADVANTAGE OF THE INVENTION According to this invention, even when it winds and stores on a axis | shaft, the manufacturing method of laminated | multilayer film etc. and laminated | multilayer film which can reduce that slack generate | occur | produces in the width direction edge part of laminated | multilayer film are provided.

(A)-(c) of Drawing 1 is a flow figure explaining a manufacturing method of a lamination film concerning one embodiment of the present invention. 2A and 2B are cross-sectional views showing examples of laminated films obtained by an embodiment of the present invention. The thickness of the resin layer is drawn as uniform for convenience. 3A is a cross-sectional view of a laminated film in which De-Dc is positive, and FIG. 3B is a cross-sectional view of a laminated film in which De-Dc is negative. FIG. 4 is a cross-sectional view of a roll in which a conventional laminated film is wound around a shaft. 5A is an enlarged view of the drying means 50 of FIG. 1, FIG. 5B is a cross-sectional view in the width direction of the laminated film in the state B of FIG. 5A, and FIG. 5C is the laminated state of the state A in FIG. It is sectional drawing of the width direction of a film. 6A is a cross-sectional view of the polarizing laminated film 10 ′, and FIG. 6B is a cross-sectional view showing an example of the cross-sectional structure of the stretched laminated film 10 ″. (A) of FIG. 7 is sectional drawing which shows the state which bonded the protective film 3 on both surfaces of polarizing laminated film 10 ', (b) of FIG. 7 is the protective film 3 and polarizer layer from the base film 1. FIG. It is sectional drawing which shows the state which obtained the polarizing plate 20 which is a 2 'laminated body. 8A shows the average thickness of the resin layer in each region R1 to R9 of Example 1, and FIG. 8B shows the average thickness of the resin layer in each region R1 to R9 of Example 1. FIG.

An embodiment of the present invention will be described with reference to the drawings.
(Laminated film manufacturing method)
FIG. 1 is a flowchart showing a method for producing a laminated film according to an embodiment of the present invention. In addition, TD shows the width direction of a base film, MD shows the longitudinal direction (conveyance direction of a base film) of a base film.

(Base film)
First, a long base film 1 is prepared. The base film 1 can be made of a thermoplastic resin. Examples of thermoplastic resins include polyolefin resins such as chain polyolefin resins and cyclic polyolefin resins (norbornene resins, etc.); polyester resins such as polyethylene terephthalate; (meth) acrylic resins; cellulose triacetate, cellulose diacetate, etc. A cellulose ester resin, a polycarbonate resin, a polyvinyl alcohol resin, a polyvinyl acetate resin, a polyarylate resin, a polystyrene resin, a polyethersulfone resin, a polysulfone resin, a polyamide resin, and a polyimide resin.

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

  Further, the base film may be a stretched product or may be unstretched. In the case of a stretched product, it may be uniaxial stretching or biaxial stretching.

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

  The copolymer mainly composed of propylene is a copolymer of propylene and another monomer copolymerizable therewith. Examples of other monomers copolymerizable with propylene include ethylene and α-olefin. As the α-olefin, an α-olefin having 4 or more carbon atoms is preferably used, and more preferably an α-olefin having 4 to 10 carbon atoms. Specific examples of the α-olefin having 4 to 10 carbon atoms include, for example, linear monoolefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-decene; 3 -Branched monoolefins such as methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene; and vinylcyclohexane. The copolymer of propylene and other monomers copolymerizable therewith may be a random copolymer or a block copolymer. Content of the said other monomer is 0.1-20 weight% in a copolymer, for example, Preferably it is 0.5-10 weight%.

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

  The base film may be composed of one type of chain polyolefin-based resin, may be composed of a mixture of two or more types of chain polyolefin-based resins, or may be composed of two or more types of chain polyolefin-based resins. You may be comprised from the copolymer of resin.

  Cyclic polyolefin resin is a general term for resins that are polymerized using cyclic olefins as polymerization units, and cyclic olefin ring-opening (co) polymers, cyclic olefin addition polymers, cyclic olefins and chain olefins such as ethylene and propylene. Copolymers (typically random copolymers), graphene polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Among these, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferably used.

  The base film may be composed of one kind of cyclic polyolefin-based resin, may be composed of a mixture of two or more kinds of cyclic polyolefin-based resins, or may be composed of two or more kinds of cyclic polyolefin-based resins. It may be composed of a polymer.

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

  Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, poly (ethylene methylene terephthalate), poly (ethylene methylene naphthalate), polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate, etc. Can be mentioned. In the case of a polyester resin film such as polyethylene terephthalate, it can be stretched in advance to increase the elastic modulus. Stretching may be uniaxial stretching or biaxial stretching.

  The base film may be composed of one kind of polyester resin, may be composed of a mixture of two or more kinds of polyester resins, or may be composed of a copolymer of two or more kinds of polyester resins. It may be configured.

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

  The base film may be composed of one (meth) acrylic resin, may be composed of a mixture of two or more (meth) acrylic resins, or may be composed of two or more (meth) acrylic resins. ) It may be composed of a copolymer of acrylic resin.

  The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, cellulose dipropionate, and the like. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferable.

  The base film may be composed of one kind of cellulose ester resin, may be composed of a mixture of two or more kinds of cellulose ester resins, or may be composed of two or more kinds of cellulose ester resins. It may be composed of a polymer.

  The polycarbonate resin is made of a polymer in which monomer units are bonded via a carbonate group. The polycarbonate resin may be a resin called a modified polycarbonate in which the polymer skeleton is modified in order to lower the photoelastic coefficient, or a copolymerized polycarbonate with improved wavelength dependency.

  The base film may be composed of one type of polycarbonate-based resin, may be composed of a mixture of two or more types of polycarbonate-based resins, or may be composed of a copolymer of two or more types of polycarbonate-based resins. It may be configured.

  Arbitrary appropriate additives other than said thermoplastic resin may be added to the base film. Examples of such additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and coloring agents. . The content of the thermoplastic resin in the base film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. If the content of the thermoplastic resin in the base film is less than 50% by weight, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited.

  Although the thickness of the base film 1 can be determined as appropriate, it is generally preferably 1 to 500 μm, more preferably 1 to 300 μm, even more preferably 5 to 200 μm from the viewpoint of workability such as strength and handleability. Most preferred is ˜150 μm.

  Although the width | variety of the base film 1 can be determined suitably, it can be 500 mm or more, and can also be 1000 mm or more. Moreover, if the length of the base film 1 is longer than a width | variety, it can determine suitably, For example, it can be set to 100 m or more, and it is suitable to set it as 500 m or more.

  From the viewpoint of suppressing defects such as wrinkles or creases in the drying process and poor drying of the coating layer, the base film can have a tensile elastic modulus at 80 ° C. of 140 MPa or more, and 150 MPa or more. More preferably, it is 155 MPa or more. Usually, it is 5000 MPa or less.

(Pretreatment of base film)
In order to improve the adhesion to the polyvinyl alcohol-based resin layer, the surface of the base film 1 can be pretreated by pretreatment means as necessary.
(Surface activation)
For example, as shown in FIG. 1A, the surface of the base film 1 supplied from the unwinding section 30 is applied to the surface of the base film 1 by surface activation means 42 such as corona treatment, plasma treatment or flame treatment. The surface activation treatment is performed, and the treated base film 1 can be wound up by the winding unit 31.

(Primer layer formation)
Moreover, in order to improve adhesiveness with a polyvinyl alcohol-type resin layer, a primer layer may also be formed on the surface of the base film 1, preferably on the surface subjected to the surface activation treatment by a primer layer forming means. it can.

  For example, as shown in FIG. 1 (b), after applying the primer layer forming coating liquid onto the surface of the base film 1 supplied from the unwinding section 32 by the coating means 44, the drying means 46 The base film having the primer layer can be obtained by drying the coating layer, and the base film 1 can be wound up by the winding unit 33 thereafter. The primer layer forming coating solution may contain a resin component and a solvent. As the resin component, a thermoplastic resin excellent in transparency, thermal stability, stretchability, and the like is preferably used, and examples thereof include (meth) acrylic resins and polyvinyl alcohol resins. As the solvent, a general organic solvent capable of dissolving the resin component and an aqueous solvent such as water are usually used.

  In order to increase the strength of the primer layer, a crosslinking agent may be added to the primer layer forming coating solution. A suitable crosslinking agent is appropriately selected from known ones such as organic and inorganic based on the type of thermoplastic resin used. As a crosslinking agent, the crosslinking agent described in WO2013 / 146644 can be used. The primer coating liquid preferably has a solid content concentration of about 1 to 25% by weight.

  The thickness of the primer layer is preferably 0.05 to 1 μm, and more preferably 0.1 to 0.4 μm.

  An example of the coating means 44 for applying the primer layer forming coating solution to the base film 1 is the same as the coating means 48 for forming a polyvinyl alcohol-based resin layer described later.

(Coating of polyvinyl alcohol resin solution)
After the pretreatment, for example, as shown in FIG. 1C, a solution of the polyvinyl alcohol resin is applied to the surface of the base film 1 supplied from the unwinding portion 34 by the coating means 48. The polyvinyl alcohol resin solution can be obtained by dissolving polyvinyl alcohol resin powder in an aqueous solvent such as water.

  Examples of polyvinyl alcohol resins are polyvinyl alcohol resins and derivatives thereof. Examples of polyvinyl alcohol resin derivatives include polyvinyl formal; polyvinyl acetal; polyvinyl alcohol resin such as olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, alkyl esters of unsaturated carboxylic acids, and acrylamide. Etc.

  100-10000 are preferable and, as for the average degree of polymerization of polyvinyl alcohol-type resin, 1000-10000 are more preferable. In particular, 1500 to 8000 is more preferable, and 2000 to 5000 is most preferable. The average degree of polymerization is a numerical value obtained by a method defined by JIS K 6726 (1994). If the average degree of polymerization is less than 100, it is difficult to obtain preferable optical characteristics. If it exceeds 10,000, the solubility in water deteriorates and it becomes difficult to form a resin layer.

The polyvinyl alcohol resin is preferably a saponified product. The range of the saponification degree is preferably 80.0 to 100.0 mol%, more preferably 90.0 to 99.5 mol%, and 93.0 to 99.5 mol%. Is more preferable. For example, a polyvinyl alcohol resin having a saponification degree of 98.0 to 99.5 mol% can be used. When the degree of saponification is less than 80.0 mol%, it is difficult to obtain preferable optical characteristics. The saponification degree is a unit ratio (mol%) representing the ratio of the acetate group contained in the polyvinyl acetate resin, which is the raw material of the polyvinyl alcohol resin, to the hydroxyl group by the saponification step.
Degree of saponification (mol%) = (number of hydroxyl groups) / (number of hydroxyl groups + number of acetate groups) × 100
It can be obtained by the method defined in JIS K 6726 (1994).

  The solid concentration in the solution is preferably 5% by weight or more, more preferably 5 to 15% by weight, still more preferably 5 to 10% by weight. If it is less than 5% by weight, the amount of water increases and the drying efficiency deteriorates. If it exceeds 15% by weight, the viscosity tends to be high and handling tends to be difficult.

  The viscosity of the solution at the time of coating is preferably 500 to 10,000 cps, more preferably 1000 to 7000 cps, and still more preferably 1000 to 5000 cps. When the viscosity is less than 500 cps, it tends to be difficult to control the film thickness, and when it exceeds 10,000 cps, liquid feeding tends to be difficult. In addition to the composition of the solution, the viscosity of the solution can also be adjusted by heating or cooling the solution.

  Examples of the aqueous solvent are water and alcohols such as methanol.

  The solution may contain additives such as a plasticizer and a surfactant as necessary. As the plasticizer, a polyol or a condensate thereof can be used, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The blending amount of the additive is preferably 20% by weight or less of the polyvinyl alcohol resin.

  Examples of the coating means 48 are wire bar coating method, roll coating method such as reverse coating, gravure coating, die coating method, comma coating method, lip coating method, spin coating method, screen coating method, fountain coating method, dipping method It can be appropriately selected from known methods such as a spray method. In the coating process of the present polyvinyl alcohol resin solution, the solution is continuously applied while the base film 1 is conveyed in the longitudinal direction. The longitudinal direction is not necessarily horizontal. The coating is preferably performed on the upper surface of the base film 1.

  The film thickness of the solution of the polyvinyl alcohol resin to be applied can be set to 50 to 200 μm, for example. The coating width of the solution can be matched with the full width of the base film 1, but may be narrower than the full width of the base film 1.

(Dry)
Subsequently, as shown in FIG. 1 (c), the coated film is dried by the drying means 50 while the substrate film 1 coated with the solution is conveyed in the longitudinal direction, and the substrate film 1 The laminated film 10 having the polyvinyl alcohol-based resin layer 2 is obtained, and then the laminated film 10 is wound around the winding unit 35. The obtained laminated film 10 has the base film 1 and the polyvinyl alcohol-type resin layer 2 as shown to (a) of FIG.

  In the drying step, the transport direction of the base film 1 is preferably the horizontal direction, but may be transported in a direction inclined with respect to the horizontal as long as it is about 45 ° with respect to the horizontal.

  In the present embodiment, in the drying step, 45 N or more per 1 m in the width direction of the base film 1 in the transport direction of the base film 1 (longitudinal direction of the base film) with respect to the base film 1 in the drying step. Give tension. That is, a tension of 45 N / m or more is applied in the longitudinal direction of the base film 1. The tension may be 50 N / m or more, or 60 N / m or more, but is usually 500 N / m or less. Further, in the drying process, the dimensional change rate in the longitudinal direction of the base film before and after the drying process may be stretched beyond 0%, that is, tension may be applied in the longitudinal direction so that plastic deformation occurs. . The dimensional change rate may be 0.01% or more, or 0.1% or more. The dimensional change rate in the drying process is preferably 5% or less, more preferably 1% or less.

  Specifically, the tension applied to the base film 1 in the drying process is controlled by controlling the driving force with which the pair of driving rolls 52 pulls out the base film 1 and the braking force of the shaft of the unwinding portion 34. it can.

The example of the drying means 50 is a floating dryer which supplies hot air from both sides of the base film and supports the base film 1 in the air without contact, and irradiates the base film 1 conveyed in the air with infrared rays. Infrared dryer, microwave dryer. It is preferable that the drying means 50 is an apparatus that can heat the resin layer of the base film 1 conveyed in the air.
The drying temperature, for example, the temperature of the resin layer at the time of drying, or the temperature of the hot air when hot air is applied to the base film 1 can be, for example, 50 to 200 ° C., and can be 60 to 150 ° C. Preferably, it is 80 ° C. or higher. When the solution contains water, these temperatures are preferably 80 ° C. or higher. The drying time, that is, the time for the transport film to travel in the drying means can be 2 to 20 minutes. In the drying step, the solution is preferably applied to the upper surface of the base film 1.

  By this drying step, as shown in FIG. 2A, a laminated film 10 having the polyvinyl alcohol-based resin layer 2 is formed on one surface of the base film 1, and a laminated film is formed on the winding unit 35. Ten rolls are obtained. The thickness of the polyvinyl alcohol-type resin layer 2 after drying can be 5-20 micrometers.

  In addition, as shown in FIG. 2B, the above-described pretreatment of the surface of the base film 1, application of the solution, and drying are performed again on the opposite surface of the base film as necessary. The laminated film 10 having the polyvinyl alcohol resin layer 2 on both surfaces of the base film 1 may be formed. Further, pretreatment and solution coating may be performed on both surfaces of the base film 1, and the coating layers provided on both surfaces of the base film 1 may be dried simultaneously. The resulting laminated film 10 can be wound into a roll.

According to this embodiment, since the tension in the transport direction applied to the base film 1 in the drying process is sufficiently large, it is suppressed that both end portions in the width direction of the polyvinyl alcohol-based resin layer 2 are thicker than the center portion. The Specifically, as shown in FIG. 2, the polyvinyl alcohol-based resin layer 2 is divided into nine equal parts in the width direction (direction orthogonal to the longitudinal direction) to form a region RN (N is an integer of 1 to 9) in order from the end. When the average film thickness of the R5 region at the center of all the regions is Dc, and the average film thickness of each of the two outermost R1 regions and R9 regions is the one with the larger difference from Dc. The following formula can be satisfied.
De-Dc ≦ 0.4 μm
De−Dc ≦ 0.3 μm or De−Dc ≦ 0 μm.
Although there is no particular lower limit value for De-Dc, De-Dc ≧ −0.5 μm or more can be used from the viewpoint of suppressing the slackness in the central portion.
In the measurement of the average film thickness, the length in the longitudinal direction of each region is not particularly limited, but may be, for example, 1 to 2 mm.

  Here, the fact that De-Dc is positive means that the end portion in the width direction of the polyvinyl alcohol-based resin layer 2 is thicker than the center portion in the width direction, as shown in FIG. De-Dc being negative means that the end portion in the width direction of the polyvinyl alcohol-based resin layer 2 is thinner than the center portion in the width direction, as shown in FIG.

  As shown in FIG. 3, when a roll is formed by winding the laminated film 10 whose end is extremely thicker than the center in the width direction around the axis sh, as shown in FIG. A tension is selectively applied to the end portion in the thick width direction in the winding direction, and the end portion extends in the longitudinal direction. Therefore, when the laminated film 10 is subsequently unwound from the roll, the end portion is loosened. This is the same even when the polyvinyl alcohol-based resin layer 2 is formed only on one side of the base film 1.

  On the other hand, according to this embodiment, it is possible to satisfy De−Dc ≦ 0.4 μm in the laminated film, and since the protrusions at both ends are reduced, it is possible to suppress the loosening of the ends that occur when the film is wound. .

  An example of the reason why the thickness of the end portion is higher than that of the central portion in the drying step will be described. As shown in FIG. 5 (a), as the drying means 50, hot air is supplied from above and below to the base film 1 conveyed in the horizontal direction by a plurality of hot air nozzles 50a, so that the base film 1 is in the air. The case where the drying means 50 that dries and transports the solution while using it will be described.

  If the tension of the base film 1 in the transport direction is not sufficient, sagging occurs in the base film 1, and as shown in FIG. As shown in b), the end portion in the width direction of the base film 1 tends to be lower than the center portion in the width direction when viewed from the longitudinal direction. When it becomes like FIG.5 (b), a solution moves to the width direction edge part, and it is thought that the thickness of the edge part of a resin layer becomes considerably higher than a center part like (a) of FIG.

  On the other hand, if the tension is sufficient, that is, within the above-mentioned range, the substrate film 1 tends to hardly wave up and down as indicated by A in FIG. 5 (a). ), The end of the base film 1 in the width direction tends to be less likely to fall than the center. Therefore, it is thought that it becomes difficult for a solution to move toward an edge part, and that the thickness of an edge part becomes considerably larger than a center part.

  In addition, when the solution is applied to both surfaces of the base film, when applied only to the upper surface of the base film, and when applied only to the lower surface of the base film Will not change. The same situation can occur even if the drying means is not floating drying. For example, the same applies even if a drying means is used in which the base film 1 does not come into contact with other members during drying, such as an infrared drying oven. Furthermore, when the solution is coated only on the upper surface, it can be dried while supporting the back surface while being in contact with one or more rolls. Even in this case, the uneven thickness in the width direction as described above may occur due to the influence of gravity between the rolls.

The longitudinal tension per unit cross-sectional area in the width direction of the base film, that is, the stress (N / m ² ) and the elastic modulus (N / m ² ) of the base film at 80 ° C. have the same dimensional quantity, and the ratio Is a value that correlates with the amount of strain that the substrate film receives during drying. When the base film is made of a polypropylene resin, the ratio of the longitudinal tension per unit cross-sectional area in the width direction of the base film to the 80 ° C. elastic modulus of the base film is preferably greater than 0.2%. Under the condition of 0.2% or less, sufficient tension is not applied to the film during drying, and it tends to be difficult to form a resin layer having a small De-Dc. Further, when the base film is made of a polyethylene terephthalate resin, the ratio of the longitudinal tension per unit cross-sectional area in the width direction of the base film to the 80 ° C. elastic modulus of the base film is a value greater than 0.06%. It is preferable that In any base film, the ratio of the longitudinal tension per unit cross-sectional area in the width direction of the base film to the 80 ° C. elastic modulus of the base film can be usually 3% or less.
In the above embodiment, each step of pretreatment, primer layer formation, and resin layer formation (coating and drying) is performed batchwise, that is, a roll of film is obtained after each step, In the next step, the film is unwound from the roll and processed, but any two or more of these steps are continuously performed, that is, two or more steps are continued without being wound on the roll. May be.

(Production method of polarizing laminated film)
Next, the obtained laminated film 10 (which may have the polyvinyl alcohol-based resin layer 2 only on one surface of the base film 1 and the polyvinyl alcohol-based resin layer 2 on both surfaces of the base film 1 May be unwound from a roll, and stretched and dyed to impart a polarizing function to the polyvinyl alcohol-based resin layer 2. Stretching may be performed before and after dyeing, dyeing may be performed before and after stretching, or stretching and dyeing may be performed simultaneously. Stretching may be performed in the air or in water. Here, the laminated film after stretching and before dyeing is called a stretched laminated film, and the film after stretching and dyeing is called a polarizing laminated film.

  Various known methods can be used for stretching. For example, it may be longitudinal stretching that extends in the longitudinal direction of the laminated film 10, transverse stretching that extends in the width direction of the laminated film 10, or oblique stretching. Especially, it is preferable to extend | stretch the laminated | multilayer film 10 longitudinally (uniaxially), conveying in a longitudinal direction. The draw ratio can be appropriately adjusted according to the required polarization characteristics, and can be, for example, 5 to 17 times, or 5 to 8 times.

  Stretching may be performed in a single stage or in multiple stages.

  Various known methods such as immersing the laminated film in a dyeing tank can be used for dyeing. For example, a dichroic dye can be used as the dye. Examples of dichroic pigments are iodine and organic dyes. In dyeing, a crosslinking treatment of polyvinyl alcohol in a resin tank may be performed. After dyeing, the laminated film is preferably washed with water and dried.

  Thereby, as shown to (a) of FIG. 6, the polarizing laminated film 10 'which has the polarizer layer 2' on the one surface or both surfaces of the base film 1 and the base film 1 is obtained. The obtained polarizing laminated film 10 ′ can be temporarily stored by being wound into a roll.

In addition, when the laminated film 10 is stretched, the thickness of each layer of the laminated film 10 is reduced. At this time, the thickness of each layer tends to be more easily reduced in the central portion in the width direction than in the end portion in the width direction. And as shown to (a) of FIG. 6, even in the case of the polarizing laminated film 10 ′ after stretching and dyeing having the base film 1 and the polarizer layer 2 ′, as shown in (b) of FIG. Even in the case of the stretched laminated film 10 '' after stretching and before dyeing having the base film 1 and the stretched resin layer 2 ″, the base film 1, the polarizer layer 2 ′, and the stretched resin layer 2 In each of '', the end tends to be thinner than the center than the end in the width direction. Here, as the De-Dc of the resin layer 2 in the laminated film 10 before stretching is smaller, De-Dc and polarizing properties in the total thickness of the base film 1 and one polarizer layer 2 'in the polarizing laminated film 10'. De-Dc in the total thickness of the base film 1 and both polarizer layers 2 'in the laminated film 10', the total thickness of the base film 1 and one stretched resin layer 2 "in the stretched laminated film 10" De-Dc and De-Dc in the total thickness of the base film 1 and both stretched resin layers 2 '' in the stretched laminated film 10 '' tend to be small.
Here, De and Dc are defined in the same manner as described above except that the layers to be subjected to thickness are different.
And in this embodiment, De-Dc in the total thickness of the base film 1 and one polarizer layer 2 'in polarizing laminated film 10' can be 1.6 micrometers or less, Preferably it is 1.2 micrometers or less. Usually, it can be set to −1.6 μm or more. De-Dc in the total thickness of the base film 1 and both polarizer layers 2 'in the polarizing laminated film 10' can be 2.0 µm or less, preferably 1.5 µm or less. It can be set to −2.0 μm or more. De-Dc in the total thickness of the base film 1 and one stretched resin layer 2 '' in the stretched laminated film 10 '' can be 1.6 μm or less, preferably 1.4 μm or less. In general, it can be -1.6 μm or more. De-Dc in the total thickness of the base film 1 and the both stretched resin layers 2 '' in the stretched laminated film 10 '' can be 2.0 μm or less, preferably 1.5 μm or less. In general, it can be -2.0 μm or more.

In the stretched laminated film 10 ″ and the polarizing laminated film 10 ′, when the end portion of the stretched polarizer layer 2 ′ is considerably higher than the central portion, these films are wound around a shaft to form a roll. Even in this case, a force may be selectively applied to the width direction end portion, which may cause a problem of looseness.
On the other hand, in the present embodiment, in the entire thickness and the polarizer layer in the laminated film 10 before stretching, the thickness of the end portion in the width direction is less likely to be thicker than that in the central portion. The film 10 ″ and the polarizing laminated film 10 ′ are also less likely to have a thickness at the end in the width direction that is larger than that at the center. Therefore, the problem of looseness after storing these as rolls is unlikely to occur.

(Production method of polarizing plate)
Then, the manufacturing method of a polarizing plate is demonstrated. First, as shown to (a) of FIG. 7, the protective film 3 is affixed on the polarizer layer 2 'of polarizing laminated film 10' via an adhesive agent. When the polarizer layer 2 ′ is provided on both surfaces of the base film 1, the protective film 3 is stuck on each polarizer layer 2 ′. Subsequently, as shown in FIG. 7B, the laminate of the protective film 3 and the polarizer layer 2 ′ is peeled from the base film 1, and the protective film 3 is bonded to the polarizer layer 2 ′ via an adhesive. Two bonded polarizing plates 20 are obtained. When the polarizing laminated film 10 ′ can have the polarizer layer 2 ′ only on one surface, one polarizing plate 20 is obtained.

  As the protective film 3, various known films can be used. For example, the film illustrated as the base film 1 can be used.

  Various known adhesives can be used as the adhesive. For example, an active energy ray curable adhesive such as an ultraviolet curable epoxy resin can be used.

  The obtained polarizing plate 20 can be wound around a shaft and stored as a roll as necessary. In the polarizing plate 20 according to this embodiment, the thickness of the width direction end of the polarizer layer 2 ′ is not so thick as compared with the thickness of the central portion of the polarizer layer 2 ′ in the width direction. Even when stored as a roll, the same effect of preventing looseness as described above can be exhibited. If necessary, the polarizing plate 20 can be unwound from the roll after storage and cut into a desired size. The obtained polarizing plate 20 can be thinned and can be suitably used as a polarizing material for a thin liquid crystal display element or the like.

Example 1
(Production of laminated film)
(Preparation of base film)
Propylene homopolymer (Sumitomo Chemical Co., Ltd. “Sumitomo Nobrene (registered trademark) FLX80E4”, melting point Tm = 163 ° C.) is blended with 1% by weight of a nucleating agent made of high-density polyethylene. A polypropylene containing a nucleating agent was prepared. From this and a propylene / ethylene random copolymer “Sumitomo Nobrene (registered trademark) W151” containing about 5% by weight of ethylene units, by means of coextrusion molding using a multilayer extrusion molding machine, “Sumitomo Nobrene (registered trademark)” A long polypropylene-based laminated film having a three-layer structure in which a resin layer made of polypropylene with a nucleating agent was placed on both sides of a resin layer made of W151 ”was prepared as a base film. The total thickness of this base film was 100 μm, and the thickness ratio of each layer (polypropylene with nucleating agent / W151 / polypropylene with nucleating agent) was 3/4/3. With respect to this base film, the tensile elastic modulus in the extrusion direction at 80 ° C., that is, the longitudinal direction, was 209 MPa.

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

(Adjustment of coating solution)
A polyvinyl alcohol powder (“Z-200” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average molecular weight 1100, average saponification degree 99.5 mol%) was dissolved in hot water at 95 ° C., and a polyvinyl alcohol aqueous solution having a concentration of 3% by weight was dissolved. It was adjusted. A coating solution for forming a primer layer was prepared by mixing 1 part by weight of a crosslinking agent (“SUMIREZ RESIN (registered trademark) 650” manufactured by Sumitomo Chemical Co., Ltd.) with 2 parts by weight of polyvinyl alcohol into the obtained aqueous solution. .

  Further, polyvinyl alcohol powder (“PVA124” manufactured by Kuraray Co., Ltd., average polymerization degree 2400, average saponification degree 98.0 to 99.0 mol%) was dissolved in 95 ° C. hot water, and the concentration of polyvinyl alcohol was 8% by weight. A coating solution for forming a polyvinyl alcohol-based resin layer, which is an aqueous solution, was prepared.

(Coating and drying)
While continuously transporting the base film in the longitudinal direction, it is subjected to corona treatment on one side, and then the primer layer coating solution is continuously applied to the corona-treated surface using a micro gravure coater, A primer layer having a thickness of 0.2 μm was formed on one side by drying at 60 ° C. for 3 minutes. Subsequently, the coating liquid for forming the polyvinyl alcohol-based resin layer was continuously applied onto each primer layer using a comma coater while transporting the film in the longitudinal direction, and a floating drying method using hot air at 90 ° C. By drying for 4 minutes, a polyvinyl alcohol-based resin layer having an average thickness of 9 μm was formed on the primer layer and wound on a shaft to obtain a roll of a laminated film. In the drying step, the tension per 1 m in the width direction applied to the base film in the longitudinal direction (conveying direction) was 64 N. The dimensional change rate of the base film in the longitudinal direction was 0.10%, and the ratio of the longitudinal tension per unit area in the width direction of the base film to the elastic modulus at 80 ° C. of the base film was 0.30%.

  Subsequently, the laminate film is unwound from the roll of the laminate film, and the same process is performed on the opposite surface of the base film, that is, corona treatment, primer layer formation, application of an aqueous polyvinyl alcohol resin solution, and drying. The laminated film which has a resin layer on both surfaces of a base film was formed, and it wound up on the axis | shaft.

  The film thickness distribution in the width direction in the total thickness of the two resin layers of the obtained laminated film was measured with an optical interference film thickness meter (“F20” manufactured by Filmmetrics) at intervals of 2000 μm or less. The resin film was equally divided into nine in the width direction, and the region R1, region R2,..., Region R9 were sequentially formed from the measurement start side, and the average value for each region was calculated. In the measurement of the average film thickness, the length in the longitudinal direction of each region was set to 1 to 2 mm. The average value of the thickness of each region is shown in FIG. Of the nine regions, the average film thickness of the central region R5 was Dc, and among the average film thicknesses of the two outermost regions R1 and R9, the larger difference from Dc was De. De-Dc was -0.2 μm. When the laminated film was unwound from the roll, almost no slack was observed at the end of the film.

(Production of stretched laminated film)
While the resulting laminated film is unwound from the roll and continuously conveyed, a free end uniaxial at a magnification of 5.8 times in the longitudinal direction (film conveying direction) at a stretching temperature of 160 ° C. using an in-roll stretching apparatus. The film was stretched and wound on a shaft to obtain a roll of a stretched laminated film. The polyvinyl alcohol resin layers after stretching had a thickness of 5.5 μm and 5.6 μm, respectively. No particular problems were observed in the stretching treatment, and almost no slack was observed at the end in the width direction of the film unwound from the roll.

(Preparation of polarizing laminated film)
While continuously transporting the obtained stretched laminated film, it was immersed in a hot water bath at 60 ° C. so that the residence time was 60 seconds, and then the residence time in a dyeing solution at 30 ° C. containing iodine and potassium iodide. The polyvinyl alcohol resin layer was dyed by dipping for about 150 seconds, and then the excess dyeing solution was washed away with pure water at 10 ° C. Subsequently, a crosslinking treatment was performed by dipping in a crosslinking solution at 76 ° C. containing boric acid and potassium iodide so that the residence time was 600 seconds. Thereafter, the film was washed with pure water at 10 ° C. for 4 seconds and dried at 80 ° C. for 300 seconds to obtain a polarizing laminated film, which was wound around a shaft to obtain a roll of the polarizing laminated film. Almost no slack was observed at the end in the width direction of the film unwound from the roll.

(Preparation of polarizing plate)
(1) Preparation of adhesive Polyvinyl alcohol powder (“KL-318” manufactured by Kuraray Co., Ltd., average polymerization degree 1800) was dissolved in 95 ° C. hot water to prepare a polyvinyl alcohol aqueous solution having a concentration of 3% by weight. The resulting aqueous solution was mixed with a crosslinking agent (“SUMIREZ RESIN (registered trademark) 650” manufactured by Sumitomo Chemical Co., Ltd.) at a ratio of 1 part by weight with respect to 2 parts by weight of the solid content of polyvinyl alcohol to obtain an adhesive solution. .

(2) Preparation of polarizing plate Next, while continuously transporting the polarizing laminated film obtained in (1) above, the adhesive solution was applied onto each polarizer layer, and then applied to the bonding surface. A saponified triacetyl cellulose (TAC) film [Konica Minolta Opto Co., Ltd. “KC4UY”, thickness 40 μm] was bonded to the adhesive solution coating surface on the polarizer layer, and between a pair of bonding rolls The film was pressure-bonded by passing it through to obtain a laminate of a polarizer layer and a protective film. Next, the base film was peeled and removed from each laminate to obtain a polarizing plate in which a protective film made of a TAC film was laminated on the polarizer layer via an adhesive layer, and a roll was obtained by winding it around a shaft. . The looseness of the end portion in the width direction of the polarizing plate unwound from the roll was improved, and the base film could be easily peeled off, and no problem was observed.

(Example 2)
The production of the laminated film was the same as Example 1 except that a tension of 85 N per 1 m in the width direction of the base film was applied in the longitudinal direction (conveying direction). The ratio of the dimensional change of the base film in the longitudinal direction is 0.25%, and the ratio of the longitudinal tension per unit area in the width direction of the base film to the elastic modulus of 80 ° C. of the base film is 0.50%. De-Dc was 0.1 μm. Further, no slack was particularly confirmed at the end in the width direction of each unwound film.

Example 3
The production of the laminated film was the same as Example 1 except that a tension of 107 N per 1 m in the width direction of the base film was applied in the longitudinal direction (conveyance direction). The ratio of the dimensional change of the base film in the longitudinal direction is 0.40%, and the ratio of the longitudinal tension per unit area in the width direction of the base film to the elastic modulus of 80 ° C. of the base film is 0.60%. De-Dc was 0.3 μm. Further, no slack was particularly confirmed at the end in the width direction of each unwound film.

Example 4
A biaxially stretched polyethylene terephthalate film having a thickness of 38 μm was selected as the base film, and in the production of the laminated film, a tension of 64 N per 1 m in the width direction of the base film was applied in the longitudinal direction (transport direction). Except this, the procedure was the same as in Example 1. The ratio of the dimensional change of the base film in the longitudinal direction is 0.01%, and the ratio of the longitudinal tension per unit area in the width direction of the base film to the elastic modulus of 80 ° C. of the base film is 0.04%. De-Dc was 0.3 μm. Further, no slack was particularly confirmed at the end in the width direction of each unwound film. The 80 ° C. elastic modulus of the base film was 3900 MPa. Moreover, although the extending | stretching process, the dyeing | staining process, and the polarizing laminated | multilayer film forming process were not implemented, when the film was unwound from the roll of the laminated | multilayer film, the slack was not confirmed by the width direction edge part.

(Example 5)
The production of the laminated film was the same as Example 4 except that a tension of 74 N per 1 m in the width direction of the base film was applied in the longitudinal direction (conveying method). The ratio of dimensional change of the base film in the longitudinal direction is 0.05%, and the ratio of the longitudinal tension per unit area in the width direction of the base film to the elastic modulus of 80 ° C. of the base film is 0.05%. De-Dc was -0.2 μm. Further, no slack was particularly confirmed at the end in the width direction of each unwound film.

(Comparative Example 1)
The production of the laminated film was the same as Example 1 except that a tension of 43 N per 1 m in the width direction of the base film was applied in the longitudinal direction (conveyance direction). The dimensional change rate of the base film in the longitudinal direction is −0.1%, and the ratio of the longitudinal tension per unit area in the width direction of the base film to the elastic modulus at 80 ° C. of the base film is 0.2%. , De-Dc was 0.7 μm. The distribution of average thickness is shown in FIG. Looseness was confirmed at the end in the width direction of each unwound film.

  Table 1 shows the experimental conditions and results of each example and comparative example. When the rate of dimensional change in the longitudinal direction is positive, it indicates stretching, and when it is negative, it indicates shrinkage.

  Moreover, about Example 1, Example 2, and the comparative example 1, the measurement result of De-Dc of each layer is shown in Table 2-Table 4 regarding a laminated film, a stretched film, and a polarizing laminated film. Here, the first surface represents the resin surface applied first, and the second surface represents the resin surface applied next.

  DESCRIPTION OF SYMBOLS 1 ... Base film, 2 ... Polyvinyl alcohol-type resin layer (resin layer), 2 '... Polarizer layer, 3 ... Protective film, 10 ... Laminated film, 10' ... Polarizing laminated film, 10 "... Stretch laminated film 20 ... Polarizing plate.

Claims (12)

A coating step of coating a solution of a polyvinyl alcohol-based resin on at least one surface of a long base film; and
A drying step of obtaining a laminated film having the base film and a resin layer by drying the solution applied while transporting the base film in the longitudinal direction,
The method for producing a laminated film, wherein in the drying step, a tension of 45 N or more per 1 m in the width direction of the base film is applied in the longitudinal direction to the base film. A coating step of coating a solution of a polyvinyl alcohol-based resin on at least one surface of a long base film; and
A drying step of obtaining a laminated film having the base film and a resin layer by drying the solution applied while transporting the base film in the longitudinal direction,
Manufacture of a laminated film that applies tension in the longitudinal direction to the base film in the drying step so that the dimensional change rate of the base film before and after the drying step is stretched beyond 0%. Method.   The method according to claim 1, further comprising a winding step of winding the laminated film around a shaft to obtain a roll of the laminated film. The process of obtaining a laminated film with the manufacturing method of the laminated film of any one of Claims 1-3, and
A method for producing a polarizing laminated film, comprising: stretching and dyeing the laminated film to obtain a polarizing laminated film having the base film and a polarizer layer.   The method according to claim 4, further comprising a winding step of winding the polarizing laminated film around an axis to obtain a roll of the polarizing laminated film. The process of manufacturing a light-polarizing laminated film by the manufacturing method of the light-polarizing laminated film of Claim 4 or 5,
A step of bonding a protective film on the polarizer layer of the polarizing laminated film via an adhesive; and
The manufacturing method of a polarizing plate provided with the process of peeling the said base film from the said polarizer layer, and obtaining a polarizing plate in this order.   The method according to claim 6, further comprising a winding step of winding the polarizing plate around an axis to obtain a roll of the polarizing plate. A long base film, and a polyvinyl alcohol resin layer provided on at least one surface of the base film,
When the polyvinyl alcohol-based resin layer is equally divided into nine regions in the direction orthogonal to the longitudinal direction of the base film, the average film thickness of the central region of the nine regions is Dc, and the outermost 2 A laminated film satisfying the following formula when De is the larger difference between Dc and the average film thickness of each of the two regions.
De-Dc ≦ 0.4 μm A long base film, and a stretched polyvinyl alcohol-based resin layer provided on one surface of the base film,
When the base film and the stretched polyvinyl alcohol-based resin layer are equally divided into nine regions in a direction orthogonal to the longitudinal direction of the base film, an average film thickness of a central region of the nine regions Is a stretched laminated film satisfying the following formula, where Dc is the average film thickness of each of the outermost two regions and De is the one with the larger difference from Dc.
De-Dc ≦ 1.6 μm A long base film, and a pair of stretched polyvinyl alcohol-based resin layers provided on both surfaces of the base film,
When the base film and the pair of stretched polyvinyl alcohol-based resin layers are equally divided into nine regions in a direction perpendicular to the longitudinal direction of the base film, the central region of the nine regions A stretched laminated film satisfying the following formula when the average film thickness is Dc and De is the difference between Dc and the average film thickness of each of the outermost two regions.
De-Dc ≦ 2.0 μm A long base film, and a polarizer layer provided on one surface of the base film,
When the base film and the polarizer layer are equally divided into nine regions in a direction perpendicular to the longitudinal direction of the base film, the average film thickness of the central region of the nine regions is Dc, A polarizing laminate film that satisfies the following formula when De is the larger difference between Dc and the average film thickness of each of the two outer regions.
De-Dc ≦ 1.6 μm A long base film, and a pair of polarizer layers provided on both surfaces of the base film,
When the base film and the pair of polarizer layers are equally divided into nine regions in a direction orthogonal to the longitudinal direction of the base film, an average film thickness of a central region of the nine regions is Dc. A polarizing laminated film satisfying the following formula when the larger difference between Dc and the average film thickness of each of the outermost two regions is De.
De-Dc ≦ 2.0 μm

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