WO2013114583A9

WO2013114583A9 - Production method for polarizing laminated film and production method for polarizing plate

Info

Publication number: WO2013114583A9
Application number: PCT/JP2012/052234
Authority: WO
Inventors: 雄一朗九内
Original assignee: 住友化学株式会社
Priority date: 2012-02-01
Filing date: 2012-02-01
Publication date: 2013-12-27
Also published as: TW201341862A; CN104081232A; JPWO2013114583A1; TWI565976B; CN104081232B; KR20140120315A; WO2013114583A1; KR101814865B1; JP6120779B2

Abstract

Provided are a production method for a polarizing laminated film and a production method for a polarizing plate using the polarizing laminated film obtained using said method. The production method for the polarizing laminated film includes: a step in which a polarizing film comprising a polarizer layer upon a base material film is prepared; and a step in which a first protective film wider than the polarizing film is arranged upon the polarizer layer in the polarizing film via a first adhesive layer, and a second protective film wider than the polarizing film is arranged upon the other surface of the polarizing film. The first and second protective films are arranged such that: both ends in the width direction of the first and second protective films are positioned further on the outside than both ends in the width direction of the polarizing film; and both ends in the width direction of the first adhesive layer are positioned further on the outside than both ends in the width direction of the polarizing film, and further on the inside than both ends in the width direction of the first and second protective films.

Description

Method for producing polarizing laminated film and method for producing polarizing plate

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

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

For example, in Japanese Patent Laid-Open No. 2000-338329 (Patent Document 1), as a method of manufacturing a thin polarizing plate, a resin layer is formed by applying a solution containing a polyvinyl alcohol-based resin on one side of a base film, and then uniaxially. A film having a polarizer layer is obtained by stretching and then dyeing, and then a protective film is bonded to the polarizer layer side of the film via an adhesive to form a polarizing laminated film, and then a base film is prepared. A method of manufacturing a polarizing plate for peeling and removing is disclosed.

JP 2000-338329 A

The film having the polarizer layer and the protective film are laminated by laminating these films via an adhesive and pressing the laminated body, for example, passing the obtained laminated body between a pair of bonding rolls. It is common to do it. However, at the time of pressure bonding of the laminated body, there is a problem that the adhesive protrudes (leaks out) from the end in the width direction, and the pressure bonding apparatus such as a bonding roll is contaminated. This problem is particularly serious in the case of continuously producing a long polarizing laminated film and a polarizing plate using a long base film and a protective film, and in such continuous production, in a crimping device such as a bonding roll. The adhering adhesive gradually transferred to the outer surface of the laminate (contact surface with the crimping device), and the polarizing laminate film and the polarizing plate itself might be contaminated.

On the other hand, in order to prevent the adhesive from protruding from the end of the laminated body, the amount of adhesive supplied is reduced, and when the laminated body is crimped, the adhesive is not interposed at both ends in the width direction. In some cases, adhesion failure occurred in the portion.

Therefore, the purpose of the present invention is to produce a polarizing laminated film and a polarizing plate that can prevent a contamination of a pressure bonding apparatus or a film surface with an adhesive while preventing adhesion failure at both end portions of the protective film when bonding. It is to provide a method.

The present invention includes the following.
[1] A polarizer layer comprising a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented on at least one surface of a base film, and having a width equal to or narrower than the width of the base film. Preparing a polarizing film comprising:
The first protection wider than the polarizing film on the one surface of the polarizing film and on the polarizer layer provided on the one surface of the base film via the first adhesive layer. Disposing a film, disposing a second protective film wider than the polarizing film on the other surface of the polarizing film to obtain a polarizing laminated film,
The width direction both ends of the first and second protective films are located outside the width direction both ends of the polarizing film, and the width direction both ends of the first adhesive layer are respectively width direction both ends of the polarizing film. The manufacturing method of the light-polarizing laminated film which arrange | positions the said 1st and 2nd protective film so that it may be located outside rather than the width direction both ends of the said 1st and 2nd protective film.

[2] After the step of disposing the first and second protective films, the both ends of the polarizing laminated film in the width direction are cut by cutting at the positions at the both ends of the polarizer layer in the width direction or at positions inside thereof. The manufacturing method of the polarizing laminated film as described in [1] which further includes the process of removing.

[3] The step of preparing the polarizing film includes:
Forming a polyvinyl alcohol-based resin layer by applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film;
Uniaxially stretching a substrate film having a polyvinyl alcohol-based resin layer;
The method for producing a polarizing laminated film according to [1], comprising a step of dyeing a polyvinyl alcohol-based resin layer of a uniaxially stretched film with a dichroic dye to form a polarizer layer.

[4] A step of preparing a polarizing laminated film produced by the method according to [2];
Removing the substrate film from the polarizing laminate film to obtain a first polarizing plate in which the first protective film is bonded to the polarizer layer.

[5] The polarizing film includes the polarizer layers on both sides of the base film,
In the step of disposing the first and second protective films, the second protective film has both ends in the width direction of the second adhesive layer on the other surface of the polarizing film via the second adhesive layer. Each of the polarizing films is disposed outside the both ends in the width direction, and disposed inside the both ends in the width direction of the first and second protective films,
The said base film is peeled and removed from the said polarizing laminated film, and the said 1st polarizing plate and the 2nd polarizing plate by which the said 2nd protective film was bonded to the said polarizer layer are obtained [4]. Manufacturing method of this polarizing plate.

According to the method of the present invention, the adhesive layer can be uniformly formed over the entire surface of the polarizing film with the protective film while preventing the adhesive from protruding from the end of the film. Therefore, according to the polarizing laminated film and the polarizing plate method of the present invention, when the protective film is bonded, it is possible to prevent the adhesion of the both ends of the film and the contamination of the pressure bonding device and the film surface by the adhesive. it can.

It is a flowchart which shows preferable embodiment of the manufacturing method of the light-polarizing laminated film which concerns on this invention, and the manufacturing method of a polarizing plate. It is a perspective view which shows an example of a bonding process typically. It is a schematic top view which shows an example of the state by which the 1st and 2nd protective film was bonded by the polarizing film in the bonding process. FIG. 4 is a schematic sectional view taken along line IV-IV shown in FIG. 3. It is a top view which shows typically the relationship between the peeling direction of the base film in a peeling process, and the orientation direction of a polarizer layer. It is a side view which shows typically the relationship between angle (phi) p which a polarizing laminated film and a 1st polarizing plate make in a peeling point, and angle (phi) k which a polarizing laminated film and a base film form.

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

<Method for producing polarizing laminated film>
FIG. 1 is a flowchart showing a preferred embodiment of a method for producing a polarizing laminate film and a method for producing a polarizing plate according to the present invention.

The manufacturing method of the light-polarizing laminated film of the present embodiment includes a step of preparing a light-polarizing film having a polarizer layer on at least one surface of the base material film, and one surface of the light-polarizing film. A first protective film is bonded and disposed on the polarizer layer provided on the one surface of the film via a first adhesive layer, and a second protective film is disposed on the other surface of the polarizing film. Thus, a laminating step S40 for obtaining a polarizing laminated film and a removing step S50 for removing both end portions in the width direction of the polarizing laminated film are included in this order.

In the present embodiment, the step of preparing the polarizing film includes a resin layer forming step S10 for forming a polyvinyl alcohol-based resin layer on at least one surface of the substrate film, and a substrate film having a polyvinyl alcohol-based resin layer. A stretching step S20 for uniaxial stretching and a staining step S30 for staining the polyvinyl alcohol resin layer of the uniaxially stretched film with a dichroic dye to form a polarizer layer are included in this order.

In the said bonding process S40, a thing wider than a polarizing film is used for a 1st and 2nd protective film. The first and second protective films are arranged on the polarizing film such that both ends in the width direction are located outside the both ends in the width direction of the polarizing film. At this time, the width of the first adhesive layer is such that both ends in the width direction of the first adhesive layer are located outside both ends in the width direction of the polarizing film and both ends in the width direction of the first and second protective films. Is also adjusted to be located inside.

As will be described later, in the present embodiment, the polarizing plate can be obtained by peeling and removing the base film from the polarizing laminated film from which both end portions in the width direction obtained by carrying out the removing step S50 are removed. (Peeling step S60).

Hereinafter, each step of S10 to S50 included in the method for producing a polarizing laminated film of the present embodiment will be described in more detail.

[1] Resin layer forming step S10
This step is a step of forming a polyvinyl alcohol-based resin layer on at least one surface of the base film. This polyvinyl alcohol-based resin layer is a layer that becomes a polarizer layer through the stretching step S20 and the dyeing step S30. In this step, the base film is continuously unwound from a roll body formed by winding a long base film, and a polyvinyl alcohol-based resin layer is continuously formed on the unwound base film. It can be carried out continuously.

The polyvinyl alcohol-based resin layer can be formed by applying a coating liquid containing a polyvinyl alcohol-based resin on the surface of the base film and drying the coating layer as necessary. According to such a method, the thickness of the polyvinyl alcohol-based resin layer and thus the polarizer layer can be reduced, which is advantageous for thinning the polarizing laminated film and the polarizing plate.

The method of applying the coating liquid is: wire 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 Or a known method such as a spray method.

In order to improve adhesion between the base film and the polyvinyl alcohol resin layer, a primer layer may be provided between the base film and the polyvinyl alcohol resin layer. From the viewpoint of adhesion, the primer layer is preferably formed from a resin composition containing a polyvinyl alcohol resin and a crosslinking agent.

In the step of applying the coating liquid, an uncoated region where the coating liquid is not applied may be provided at both ends in the width direction of the base film. An uncoated area | region can be an area | region of 0.5 cm or more and 20 cm or less (preferably 10 cm or less) respectively from the width direction both ends of a base film inside. By providing an uncoated region, it is possible to suppress warping of both end portions in the width direction of the base film that may occur when the coating layer is dried. This uncoated region may cause undulation that may cause the film to break in the stretching step S20 or in the case where the film is wound after that, prior to the stretching step S20 or in the stretching step S20. The uncoated area may be removed by cutting after the film is wound up.

When the coating liquid is applied to the entire surface of the base film, the width of the polyvinyl alcohol-based resin layer (and hence the polarizer layer) is the same as the width of the base film. On the other hand, when providing the said uncoated area | region and applying a coating liquid, the width | variety of a polyvinyl-alcohol-type resin layer (hence, polarizer layer) becomes narrower than the width | variety of a base film.

The coating layer is dried in order to remove the solvent from the coating layer when the coating solution contains the solvent. The drying temperature and drying time are set according to the type of solvent. The drying temperature is, for example, 50 to 200 ° C., preferably 60 to 150 ° C. The drying time is, for example, 2 to 20 minutes.

The polyvinyl alcohol-based resin layer may be formed only on one side of the base film or on both sides, but two polarizing plates can be obtained from one polarizing laminated film. From the standpoint of improving productivity, it is preferable to form a polyvinyl alcohol-based resin layer on both sides of the base film. In this case, it is preferable to form the said primer layer on both surfaces of a base film. Moreover, when forming a polyvinyl alcohol-type resin layer on both surfaces of a base film, these polyvinyl alcohol-type resin layers are normally formed so that the formation position in a base film surface may correspond.

The thickness of the polyvinyl alcohol resin layer is preferably more than 3 μm and not more than 30 μm, more preferably 5 to 20 μm. If it is a polyvinyl alcohol-based resin layer having a thickness within this range, polarized light having a sufficiently small dichroic dyeing property, excellent polarization characteristics, and sufficiently small thickness through a stretching step S20 and a dyeing step S30 described later. A child layer can be obtained. When the thickness of the polyvinyl alcohol-based resin layer exceeds 30 μm, the thickness of the polarizer layer may exceed 10 μm.

(Coating fluid)
The coating liquid is preferably a polyvinyl alcohol resin solution obtained by dissolving a polyvinyl alcohol resin powder in a good solvent (for example, water). Examples of the polyvinyl alcohol resin include polyvinyl alcohol resins and derivatives thereof. Derivatives of polyvinyl alcohol resin include polyvinyl formal, polyvinyl acetal, etc., olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, and alkyl esters of unsaturated carboxylic acids. And those modified with acrylamide or the like. Among the above-mentioned polyvinyl alcohol resins, it is preferable to use a polyvinyl alcohol resin.

The average degree of polymerization of the polyvinyl alcohol resin is preferably 100 to 10,000, and more preferably 1000 to 10,000. The average saponification degree of the polyvinyl alcohol-based resin is preferably 80 to 100 mol%, and more preferably 94 mol% or more.

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

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

The base film is composed of a chain polyolefin resin, a cyclic polyolefin resin, a (meth) acrylic resin for reasons such as excellent smoothness for applying the coating liquid and excellent stretchability in the stretching step S20. And at least one selected from the group consisting of cellulose ester resins.

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.

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. In particular, the base film is made of polypropylene resin (polypropylene resin which is a homopolymer of propylene, copolymer mainly composed of propylene, etc.), polyethylene resin (polyethylene resin which is a homopolymer of ethylene, or ethylene). More preferably, the main component is a copolymer or the like.

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

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

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

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

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

The base film 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.

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

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

In addition, film names such as “ESCINA” (manufactured by Sekisui Chemical Co., Ltd.), “SCA40” (manufactured by Sekisui Chemical Co., Ltd.), “ZEONOR FILM” (manufactured by Nippon Zeon Co., Ltd.), etc. You may use the commercial item of the made cyclic polyolefin resin film as a base film.

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

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

Polyester resins other than polyethylene terephthalate and copolymerized polyethylene terephthalate include polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate. A phthalate etc. are mentioned.

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.

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

The base film 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, and cellulose dipropionate. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferable. Many products of cellulose triacetate are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available cellulose triacetate are “Fujitac TD80” (manufactured by Fuji Film Co., Ltd.), “Fujitac TD80UF” (manufactured by Fuji Film Co., Ltd.), “Fujitac TD80UZ” (Fuji Film ( Co., Ltd.), “Fujitac TD40UZ” (manufactured by FUJIFILM Corporation), “KC8UX2M” (manufactured by Konica Minolta Opto Corporation), “KC4UY” (manufactured by Konica Minolta Opto Corporation), and the like.

The base film 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.

Polycarbonate resin is an engineering plastic made of a polymer in which monomer units are bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency. The polycarbonate-based resin constituting the base film may be a resin called a modified polycarbonate in which the polymer skeleton is modified in order to lower the photoelastic coefficient, a copolymer polycarbonate having improved wavelength dependency, or the like.

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

The base film 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.

Any appropriate additive may be added to the base film in addition to the above thermoplastic resin. Examples of such additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and coloring agents. . The content of the thermoplastic resin in the base film 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.

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

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

In another embodiment, the polyvinyl alcohol-based resin layer can be formed by sticking a film made of a polyvinyl alcohol-based resin on a base film, but in this case, an adhesive is used for sticking between the films. Can be used. Thus, even when using a film made of a polyvinyl alcohol-based resin, the film made of a polyvinyl alcohol-based resin is a base material so that the width of the polarizer layer is the same as or narrower than the width of the base film. A film made of a polyvinyl alcohol resin having the same width as that of the film or narrower than that of the film is used.

[2] Stretching step S20
This step is a step of obtaining a stretched film by uniaxially stretching a base film having a polyvinyl alcohol-based resin layer. Also in this step, the long film obtained through the resin layer forming step S10 is continuously stretched while being conveyed, or the long film obtained through the resin layer forming step S10 is once rolled. It can carry out continuously by carrying out an extending | stretching process, winding up in a shape and continuously unwinding a film from this roll body.

The draw ratio of the film can be appropriately selected according to the desired polarization characteristics, but is preferably more than 5 times and 17 times or less, more preferably more than 5 times and less than 8 times the original length of the film. is there. When the draw ratio is 5 times or less, the polyvinyl alcohol-based resin layer is not sufficiently oriented, and the degree of polarization of the polarizer layer may not be sufficiently high. On the other hand, when the draw ratio exceeds 17 times, the film is likely to break during stretching, and the thickness of the stretched film becomes unnecessarily thin, and the workability and handleability in the subsequent process may be reduced.

The stretching process is not limited to one-stage stretching, and can be performed in multiple stages. In this case, all of the multistage stretching processes may be performed continuously before the dyeing process S30, or the second and subsequent stretching processes may be performed simultaneously with the dyeing process and / or the crosslinking process in the dyeing process S30. Good. Thus, when performing a extending | stretching process in multistage, it is preferable to perform an extending | stretching process so that it may become a draw ratio exceeding 5 times combining all the stages of an extending | stretching process.

The stretching treatment may be longitudinal stretching that extends in the film longitudinal direction (film transport direction), and may be lateral stretching or oblique stretching that extends in the film width direction. Examples of the longitudinal stretching method include inter-roll stretching and compression stretching, and examples of the lateral stretching method include a tenter method.

As the stretching treatment, either a wet stretching method or a dry stretching method can be adopted, but it is preferable to use the dry stretching method because the stretching temperature can be selected from a wide range.

The stretching temperature is set to be equal to or higher than the temperature at which the polyvinyl alcohol-based resin layer and the entire base film can be stretched, and preferably in the range of −30 ° C. to + 30 ° C. of the phase transition temperature of the base film. More preferably, it is in the range of −25 ° C. to + 5 ° C. of the phase transition temperature of the base film. The phase transition temperature of the base film means a glass transition temperature Tg when the resin constituting the base film is an amorphous resin, and a melting point (crystalline melting point) Tm when the resin is a crystalline resin. Both are measured according to JIS K7121. When the base film is composed of a plurality of resin layers, the phase transition temperature means the highest phase transition temperature among the phase transition temperatures exhibited by the plurality of resin layers.

When the stretching temperature is lower than the phase transition temperature of −30 ° C., it is difficult to achieve high-magnification stretching of more than 5 times. When the stretching temperature exceeds + 30 ° C. of the phase transition temperature, the fluidity of the base film tends to be too high and stretching tends to be difficult.

Since it is easier to achieve a high draw ratio of more than 5 times, the drawing temperature is within the above range, and more preferably 120 ° C. or higher. The temperature adjustment of the stretching process is usually performed by adjusting the temperature of the heating furnace.

[3] Dyeing step S30
In this step, the polyvinyl alcohol-based resin layer of the stretched film is dyed with a dichroic dye and adsorbed and oriented to form a polarizer layer. Through this step, a polarizing film in which a polarizer layer is laminated on a base film is obtained. In this process, the continuous stretched film obtained through the stretching step S20 is continuously dyed while being conveyed, or the stretched film obtained through the stretching step S20 is temporarily wound into a roll, It can carry out continuously by dyeing | staining continuously, unwinding a film from this roll body.

Examples of dichroic pigments include iodine and organic dyes. Specific examples of organic dyes include, for example, Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Including Blue, Direct First Orange S, First Black. A dichroic dye may be used individually by 1 type, and may use 2 or more types together.

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

When iodine is used as the dichroic dye, it is preferable to further add an iodide to the dyeing solution containing iodine because the dyeing efficiency can be further improved. Examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Is mentioned. The concentration of iodide in the dyeing solution is preferably 0.01 to 10% by weight. Of the iodides, it is preferable to add potassium iodide. When potassium iodide is added, the ratio of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, more preferably in the range of 1: 6 to 1:80. A range of 1: 7 to 1:70 is particularly preferable.

The immersion time of the stretched film in the dyeing solution is usually in the range of 15 seconds to 15 minutes, preferably 30 seconds to 3 minutes. The temperature of the dyeing solution is preferably in the range of 10 to 60 ° C., more preferably in the range of 20 to 40 ° C.

In addition, although it is also possible to perform dyeing process S30 before extending | stretching process S20 or simultaneously, the extending | stretching process in extending process S20 so that the dichroic dye adsorb | sucked to the polyvinyl alcohol-type resin layer can be favorably oriented. It is preferable to carry out the dyeing step S30 after carrying out at least a part of the above. As an embodiment in this case, 1) an embodiment in which the dyeing step S30 is performed without the drawing treatment after the drawing treatment at the target magnification, and 2) the dyeing is performed after the drawing treatment at a magnification lower than the target. During the dyeing process in step S30 (when the dyeing process S30 includes a cross-linking process), the drawing process is performed so that the total magnification becomes the target magnification. 3) A magnification lower than the target After the stretching process is performed, the total magnification is not extended to the target magnification during the dyeing process in the dyeing process S30 (when the dyeing process S30 includes a crosslinking process, the dyeing process and / or the crosslinking process). Examples of the method include performing the treatment and then performing a stretching treatment so that the total magnification becomes a target magnification.

The dyeing step S30 can include a cross-linking treatment step performed subsequent to the dyeing treatment. The crosslinking treatment can be performed by immersing the dyed film in a solution containing a crosslinking agent (crosslinking solution). As the crosslinking agent, conventionally known substances can be used, and examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. A crosslinking agent may be used individually by 1 type, and may use 2 or more types together.

Specifically, the crosslinking solution can be a solution in which a crosslinking agent is dissolved in a solvent. As the solvent, for example, water can be used, but an organic solvent compatible with water may be further included. The concentration of the crosslinking agent in the crosslinking solution is preferably in the range of 1 to 20% by weight, more preferably in the range of 6 to 15% by weight.

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

The immersion time of the dyed film in the crosslinking solution is usually 15 seconds to 20 minutes, preferably 30 seconds to 15 minutes. The temperature of the crosslinking solution is preferably in the range of 10 to 90 ° C.

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

It is preferable to perform a washing process and a drying process after the dyeing process S30 and before the bonding process S40. The washing process usually includes a water washing process. The water washing treatment can be performed by immersing the film after the dyeing treatment or after the crosslinking treatment in pure water such as ion exchange water or distilled water. The water washing temperature is usually in the range of 3 to 50 ° C., preferably 4 to 20 ° C. The immersion time in water is usually 2 to 300 seconds, preferably 3 to 240 seconds.

The washing step may be a combination of a water washing step and a washing step with an iodide solution. Moreover, the washing | cleaning liquid used by the washing process by a water washing | cleaning process and / or an iodide solution can contain liquid alcohols, such as methanol, ethanol, isopropyl alcohol, butanol, propanol, other than water suitably.

Any appropriate method such as natural drying, blow drying, or heat drying can be adopted as the drying step performed after the washing step. For example, in the case of heat drying, the drying temperature is usually 20 to 95 ° C., and the drying time is usually about 1 to 15 minutes.

[4] Pasting step S40
This step is on one surface of a polarizing film having a polarizer layer on one side or both sides of the base film, and on the polarizer layer it has, the first protective film via the first adhesive layer Is a step of obtaining a polarizing laminated film by placing a second protective film on the other surface of the polarizing film, preferably via a second adhesive layer. Also in this step, the first and second protective films are continuously formed from the rolls formed by winding the long first and second protective films while conveying the polarizing film obtained through the dyeing step S30. By continuously feeding the adhesive continuously between the polarizing film and the first protective film (or further between the polarizing film and the second protective film) and performing continuous bonding, Alternatively, the polarizing film obtained through the dyeing step S30 is once wound up in a roll shape, and the long first and second protective films are wound while the polarizing film is continuously unwound from the roll body. The first and second protective films are continuously unwound from each roll body, and between the polarizing film and the first protective film (or further, the polarizing film and the second protective film). The adhesive was continuously fed in between) the beam can be carried out continuously by the continuous lamination.

Hereinafter, with reference to FIGS. 2 to 4, the polarizing film has a polarizer layer on both surfaces of the base film, and the second protective film is polarized through the second adhesive layer in the bonding step S40. The bonding step S40 will be described in detail with an embodiment in which the bonding is performed on the adhesive film as an example.

FIG. 2 is a perspective view schematically showing an example of the bonding step S40. FIG. 3: is a schematic top view which shows an example of the state by which the 1st and 2nd protective film was bonded by the polarizing film in bonding process S40, and showed the formation area of the adhesive bond layer typically. is there. 4 is a schematic cross-sectional view taken along the line IV-IV shown in FIG.

2 to 4, a first protective film 200 and a second protective film bonded to one surface and the other surface of a polarizing film in which a polarizer layer 110 is laminated on a base film 100. As the film 300, a film having a width wider than that of the polarizing film (in other words, the base film 100) is used. That is, the width W ₂ of the first protective film 200> the width W ₁ of the polarizing film (base film 100) is satisfied, and the width W ₃ of the second protective film 300> the width of the polarizing film (base film 100). meet the W _1. 2 to 4 show the non-coated areas 120 and 130 (areas where the polarizer layer 110 is not formed) where the coating liquid is not applied to both end portions in the width direction of the base film 100 as the polarizing film. The example using what provided is shown.

The first and second

protective films

200 and 300 are each made of an adhesive S such that both ends in the width direction are located outside the both ends in the width direction of the polarizing film (base film 100). It is bonded to the polarizing film via the first adhesive layer 250 and the second adhesive layer 350 made of the adhesive T. The 1st and 2nd

protective films

200 and 300 can be laminated | stacked and bonded so that those width direction centers may correspond with the width direction center of a polarizing film, or substantially correspond. The bonding temperature is usually in the range of 15 to 40 ° C.

At this time, the first adhesive layer 250 and the second adhesive layer 350 have both ends in the width direction located outside the both ends in the width direction of the polarizing film, and the first and second

protective films

200 and 300. These widths are adjusted and formed so as to be located inside the both ends in the width direction.

Therefore, in the laminated film in a state where the first and second

protective films

200 and 300 are bonded to the polarizing film, both end portions in the width direction are between the first protective film 200 and the second protective film 300. The width of the first and second

adhesive layers

250 and 350 is the width of the polarizing film (base film 100) to such an extent that the adhesive layer is formed up to a part of this portion. Is wider than.

According to the bonding method as described above, the adhesive layer is uniformly distributed over the entire bonding surface of the polarizing film with the first and second

protective films

200 and 300 without causing the absence of the adhesive layer. Since it is formed, the polarizing laminated film excellent in the adhesiveness between the polarizing film and the first and second

protective films

200 and 300, and thus the adhesiveness between the polarizer layer 110 and the first and second

protective films

200 and 300. Can be stably produced.

Also, it is possible to prevent the adhesive from protruding from the end in the width direction of the laminated film at the time of film bonding and the contamination of the pressure bonding apparatus such as a bonding roll. Even when continuous bonding is performed using the long polarizing film, the first and second

protective films

200 and 300, contamination of the crimping apparatus due to the protruding adhesive and contamination of the surface of the laminated film is prevented. However, the polarizing laminated film, and thus the polarizing plate can be produced stably and continuously.

The polarizing film and the first and second

protective films

200 and 300 include, for example, an adhesive S between the polarizing film and the first protective film 200, and between the polarizing film and the second protective film 300, respectively. The first protective film 200 is applied on at least one film to which the adhesive T is supplied or bonded, and then the first adhesive layer 250 made of the adhesive S is provided on one surface of the polarizing film. And the second protective film 300 is laminated on the other surface via the second adhesive layer 350 made of the adhesive T to form a laminated film, and the laminated film is passed between a pair of bonding rolls. Bonding can be performed by a method of pressure bonding using a pressure bonding apparatus.

As a method for supplying an adhesive between at least one film to be supplied or bonded between films, an adhesive feed nozzle tip is arranged between the films, and a pump or the like is used from the nozzle. Adhesive supply method: Adhesive on at least one film adhesive surface by casting method, Meyer bar coating method, gravure coating method, comma coater method, doctor plate method, die coating method, dip coating method, spraying method, etc. The method of coating etc. can be mentioned. Any of the above methods enables continuous supply and continuous coating of the adhesive.

In order to adjust the width of the first and second

adhesive layers

250 and 350 to the predetermined width, the supply amount or coating amount of the adhesive, the pressure applied by the pressure bonding device (when using the bonding roll, the bonding What is necessary is just to adjust the distance between joint rolls), the conveyance speed of a film, etc. In addition, when continuous bonding is performed using the long polarizing film and the first and second

protective films

200 and 300, the adhesive is continuously supplied between the films, while being laminated through the adhesive layer. It is possible to carry out the bonding process while continuously sucking the excess adhesive overflowing from the width direction end of the film using a suction device. In this case, adjust the suction amount of the adhesive. Also, the width of the first and second

adhesive layers

250 and 350 can be adjusted.

When the polarizing film has a polarizer layer only on one side of the base film, the second protective film does not go through the second adhesive layer in the bonding step S40 (with the side having the polarizer layer in the polarizing film; May be disposed directly on the polarizing film (without supplying adhesive T between the opposite surface and the second protective film), but is preferably disposed via the second adhesive layer. When the second protective film is disposed directly on the polarizing film without the second adhesive layer, the first and second

protective films

200 and 300 are polarizing at both ends in the width direction of the first adhesive layer 250, respectively. It arrange | positions on a polarizing film so that it may be located outside the width direction both ends of a film, and may be located inside the width direction both ends of the 1st and 2nd

protective films

200 and 300. FIG.

(First and second protective film)
As the first and

second protection films

200 and 300, those are the width W _2, W ₃ thereof, as described above wider than the width W ₁ of the polarizing film (base film 100) is used (W _2, W _3> W _1). The widths W ₂ and W ₃ may be the same or different, but are usually the same width.

The difference between the widths W ₂ and W ₃ and the width W ₁ is that the portion where the polarizing film does not exist between the first protective film 200 and the second protective film 300 at the both end portions in the width direction of the laminated film is sufficient. In order to effectively widen and prevent the adhesive from protruding, it is preferably 40 mm or more, and more preferably 80 mm or more. The length in the width direction of the portion where the polarizing film does not exist is preferably 20 mm or more, and more preferably 40 mm or more for each of both end portions in the width direction of the laminated film.

On the other hand, if too large a width W _2, W _3, since there is a disadvantage in terms of productivity becomes large portion to be cut and removed in the removing step S50 to be described later (effective use of raw materials), and a width W _2, W ₃ The difference from the width W ₁ is preferably 100 cm or less, more preferably 60 cm or less, and even more preferably 40 cm or less.

The first and second

protective films

200 and 300 are, for example, polyolefin resins such as chain polyolefin resin (polypropylene resin, etc.) and cyclic polyolefin resin (norbornene resin, etc.); cellulose triacetate, cellulose diacetate, etc. Cellulose ester-based resins; Polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; Polycarbonate resins; (Meth) acrylic resins; or a mixture or copolymer thereof. . Examples of commercially available products of cyclic polyolefin resin and film thereof, and cellulose triacetate are as described above.

The first protective film 200 and the second protective film 300 may be made of the same material or different materials.

The first and / or second

protective films

200 and 300 may be protective films having an optical function such as a retardation film and a brightness enhancement film. For example, a retardation film provided with an arbitrary retardation value by stretching a transparent resin film made of the above material (uniaxial stretching or biaxial stretching) or forming a liquid crystal layer or the like on the film. It can be.

The thickness of the first and second

protective films

200 and 300 is preferably 90 μm or less, and more preferably 50 μm or less, from the viewpoint of thinning the polarizing laminated film and the polarizing plate. On the other hand, from the viewpoint of securing strength, the thickness of the first and second

protective films

200 and 300 is preferably 5 μm or more.

In order to improve the adhesiveness with the adhesive layer, the primer surface, plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification are applied to the adhesive surfaces of the first and second

protective films

200 and 300. It is preferable to perform surface treatment such as treatment. Of these, corona treatment and saponification treatment that can be carried out relatively easily are suitable. Examples of the saponification treatment include a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

It is preferable to appropriately select the surface treatment so as to obtain a sufficient effect of improving the adhesion depending on the types of resins constituting the first and second

protective films

200 and 300. For example, when a cellulose ester resin film is used, a saponification treatment is effective. Further, when using a film made of a chain polyolefin resin such as a polypropylene resin, a cyclic polyolefin resin, a polyester resin, a polycarbonate resin or a (meth) acrylic resin, a corona treatment is effective. .

A surface treatment may be applied to the adhesive surface of the polarizing film instead of or along with the surface treatment of the protective film.

An optical layer such as a hard coat layer, an antiglare layer, or an antireflection layer can be formed on the surface of the first and / or second

protective film

200, 300 opposite to the polarizer layer. The method for forming these optical layers on the surface of the protective film is not particularly limited, and a known method can be used. The optical layer may be formed in advance on the protective film prior to the bonding step S40, or after the bonding step S40, after the removal step S50 or after the peeling step S60. Also good.

(adhesive)
As adhesive S used for bonding with the 1st protective film 200 and a polarizing film, adhesive T used as needed for bonding with the 2nd protective film 300 and a polarizing film, water system adhesion An agent or a photocurable adhesive can be used.

The adhesive S and the adhesive T may be the same type or different types, but it is preferable to use the same type of adhesive from the viewpoint of production efficiency.

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

Polyvinyl alcohol resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. A polyvinyl alcohol copolymer obtained by saponifying a polymer or a modified polyvinyl alcohol polymer obtained by partially modifying a hydroxyl group thereof can be used.

The water-based adhesive can contain additives such as polyhydric aldehydes, water-soluble epoxy compounds, melamine compounds, zirconia compounds, and zinc compounds. When an aqueous adhesive is used, the thickness of the adhesive layer obtained therefrom is usually 1 μm or less.

When using an aqueous adhesive, after carrying out the above-mentioned bonding (lamination of the film through the adhesive layer and pressure application by a pressure bonding device), the film is dried to remove the water contained in the aqueous adhesive. It is preferable to carry out a drying step. Drying can be performed by introducing the film into a drying oven.

The drying temperature (drying furnace temperature) is preferably 30 to 90 ° C. If the temperature is lower than 30 ° C., the polarizing film and the protective film tend to be peeled off. On the other hand, if the drying temperature exceeds 90 ° C., the polarization performance may be deteriorated by heat. The drying time can be 10 to 1000 seconds, and from the viewpoint of productivity, it is preferably 60 to 750 seconds, and more preferably 150 to 600 seconds.

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

The above drying step and curing step may be performed before the removal step S50 or after the removal step S50 when performing the removal step S50 described later. However, when producing a polarizing plate using the polarizing laminated film obtained through bonding process S40 (namely, when peeling process S60 is implemented), a drying process and a curing process are performed before peeling process S60.

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

As described above, when an uncoated region is provided in the resin layer forming step S10, undulation may occur in the uncoated region in the stretching step S20 or the like. When the bonding step S40 is performed using a photocurable adhesive in a state where such undulation has occurred, a part of the photocurable adhesive accumulates in the undulated portion, and yellowing deterioration due to heat during irradiation with active energy rays There is a risk. Therefore, it is preferable to remove the uncoated region from the viewpoint of avoiding this yellowing deterioration.

When using a photocurable adhesive, after performing the above-mentioned pasting (lamination of a film through an adhesive layer and pressure application by a pressure bonding apparatus), a drying process is performed as necessary (the photocurable adhesive is Next, a curing step of curing the photocurable adhesive by irradiating active energy rays is performed. The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, the low-pressure mercury lamp, the medium-pressure mercury lamp, the high-pressure mercury lamp, the ultrahigh-pressure mercury lamp, the chemical lamp, and the black light lamp A microwave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive, and the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW / cm ^2. It is preferable to set to. When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when the irradiation intensity is 6000 mW / cm ² or less, the light emitted from the light source and the heat generated during the curing of the photocurable adhesive There is little risk of yellowing of the curable adhesive and deterioration of the polarizer layer.

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

The thickness of the adhesive layer after irradiation with active energy rays is usually about 0.001 to 5 μm, preferably 0.01 to 2 μm, more preferably 0.01 to 1 μm.

The drying step and the curing step may be performed before the removal step S50 or after the removal step S50 when performing the removal step S50 described later. However, when producing a polarizing plate using the polarizing laminated film obtained through bonding process S40 (namely, when peeling process S60 is implemented), a drying process and a hardening process are performed before peeling process S60.

[5] Removal step S50
This step is a step of removing both ends in the width direction of the polarizing laminated film obtained through the bonding step S40 (or drying step, curing step or curing step) by cutting. This process also has a long polarizing property obtained by continuously performing a removing process while conveying a long polarizing laminated film obtained through the bonding step S40 or through the bonding step S40. It can be carried out continuously by winding the laminated film once in a roll and continuously removing the polarizing laminated film from the roll body while continuously removing it.

This step can be omitted when the polarizing laminated film obtained through the bonding step S40 is used as it is as a polarizing element, but from the polarizing laminated film obtained through the bonding step S40. This is an essential step when a polarizing plate is produced (that is, when the peeling step S60 is performed).

An example of the cutting position of the film is as shown in FIG. 3, which is the position at both ends in the width direction of the polarizer layer 110 or the position inside thereof, that is, the first protective film 200 and the second protective film 300. And a portion directly bonded by an adhesive layer (with no polarizing film interposed), and the polarizing film has uncoated regions 120 and 130 (regions where the polarizer layer 110 is not formed). In this case, it is a position where at least a portion where the protective film and the base film are directly bonded by the adhesive layer (without the polarizer layer 110 interposed) can be removed.

By removing both end portions in the film width direction at such cutting positions, the base film 100 can be easily peeled from the polarizer layer 110 in the peeling step S60.

Removal of both end portions in the film width direction can be performed by a die cutting method or a slit method using a slitter. Especially, the slit method which can perform a removal process continuously with respect to a elongate polarizing laminated film is preferable.

Examples of the slit method include a method using a razor blade called a leather blade as a slitter. The slitting method using a razor blade includes a hollow cutting method that slits in the air without providing a backup guide; a grooved roll method that stabilizes the meandering of the slit by inserting the blade into a grooved roll as a backup guide .

Another example of the slit method is a method in which two circular blades called shear blades are used for slitting by applying contact pressure to the lower blade with the upper blade while rotating according to the conveyance of the film; There is a method of slitting by pressing a so-called blade against a quenching roll; a method of slitting while cutting like two scissors by combining two shear blades.

Among them, the “groove roll method using a leather blade”, which is a method that can easily change the cutting (slit) position of the film and that is easy to stabilize, is preferably used.

Since the apparatus used for the removal step S50 is not so large, it can be incorporated in the inline of any of the above steps S10 to S40. For example, if a slitter is arrange | positioned in the winding-up part which winds up the polarizing laminated film obtained through bonding process S40, a slit can be performed, winding up a polarizing laminated film.

Further, it is of course possible to provide an apparatus used for the removal step S50 independently of these steps without being incorporated in the in-line of any of the steps S10 to S40. As such an example, a slitter may be installed in a device called a rewinder that performs roll rewinding.

The polarizing laminated film from which both end portions in the film width direction are removed can be used as a polarizing element as it is, and a polarizing plate comprising a polarizer layer and a protective film is prepared (subjected to a peeling step S60 described later). It is also useful as an intermediate.

<Production method of polarizing plate>
The manufacturing method of the polarizing plate of this invention contains the process of preparing the above-mentioned polarizing film, bonding process S40, removal process S50, and peeling process S60 (refer FIG. 1). Since the steps other than the peeling step S60 are as described above, description thereof will be omitted. According to the method of the present invention, as in the case of the polarizing laminated film, the polarizer layer and the protective film are prevented from sticking out of the adhesive and accompanying contamination of the crimping device such as a bonding roll and contamination of the film surface. It is possible to stably produce a polarizing plate excellent in adhesiveness.

[6] Peeling step S60
In this step, referring to FIG. 4, the base film 100 is peeled off from the polarizing laminated film from which both end portions in the width direction obtained through the removing step S <b> 50 are removed, and the first protective film is formed on the polarizer layer 110. It is a step of obtaining at least a first polarizing plate to which 200 is bonded.

As in the example shown in FIG. 4, the polarizer layer 110 is formed on both surfaces of the substrate film 100, and the second protective film 300 is bonded to the polarizing film via the second adhesive layer 350 in the bonding step S <b> 40. In the case of being bonded to the top, two polarizing plates, that is, the first polarizing plate and the second polarizing plate in which the second protective film 300 is bonded to the polarizer layer 110 can be obtained by this step. it can. When the polarizer layer 110 is formed only on one surface of the base film 100 (only on the first protective film 200 side), one polarizing plate (first polarizing plate) is obtained by this step.

Also in this step, the long polarizing laminated film obtained by continuously performing the peeling treatment while carrying the long polarizing laminated film obtained through the removing step S50, or through the removing step S50. Can be continuously carried out by winding the film into a roll and continuously performing a peeling treatment while continuously unwinding the polarizing laminated film from the roll.

The method for peeling and removing the base film is not particularly limited, and can be peeled by the same method as the separator (peeling film) peeling step performed by a normal pressure-sensitive adhesive polarizing plate.

FIG. 5 is a view showing an example of a peeling method of the base film in the peeling step S60, and is a top view schematically showing the relationship between the peeling direction of the base film and the orientation direction of the polarizer layer. In FIG. 5, the base film 600 is peeled from the polarizing laminated film 500, and the 1st polarizing plate 700 which consists of a 1st protective film and a polarizer layer is formed. In FIG. 5, the second protective film laminated on the base film 600 is omitted.

[Correction based on Rule 91 19.08.2013]
The orientation direction of the polarizer layer is indicated by an arrow A, the peeling direction of the base film 600 is indicated by an arrow B, and the peeling direction (arrow B) of the base film 600 and the orientation direction of the polarizer layer (arrow A) are formed. The angle is indicated by θ. At this time, the angle θ formed by the peeling direction of the base film 600 (arrow B) and the orientation direction of the polarizer layer (arrow A) is 20 degrees or less, preferably 10 degrees or less, more preferably 5 degrees or less (for example, 0 It is preferable to peel so that it may become (degree). By peeling so that the angle θ is 20 degrees or less, the base film 600 can be peeled cleanly and smoothly without causing cohesive failure in the polarizer layer. The orientation direction of the polarizer layer is a direction in which the main chains of the polyvinyl alcohol-based resin constituting the polarizer layer are aligned by stretching, and is the direction having the highest refractive index in the plane of the polarizer layer.

Also, as shown in FIG. 6, at the peeling point C between the base film 600 and the first polarizing plate 700, the angle φp formed by the polarizing laminated film 500 and the first polarizing plate 700 before peeling the base film is It is preferable to peel the base film 600 so as to be smaller than the angle φk formed by the polarizing laminated film 500 and the base film 600 before peeling the base film. φp is preferably 45 degrees or less, more preferably 0 degrees. By peeling the base film 600 so that φp <φk and further φp ≦ 45 degrees, cohesive failure occurring in the polarizer layer can be suppressed, and the base film 600 can be peeled smoothly.

FIG. 6 shows a state in which the base film 600 and the first polarizing plate 700 are peeled off at an angle in the opposite direction with respect to the polarizing laminated film 500 at the peeling point C. The base film 600 and the first polarizing plate 700 may be peeled so as to form an angle in the same direction with respect to the conductive laminated film 500. Even in this case, the above-described conditions regarding the angles φp and φk are effective. It is.

As mentioned above, with reference to FIG.5 and FIG.6, although the base film was peeled from the light-polarizing laminated film and the method of obtaining a 1st polarizing plate was described, it peeled a base film from a light-polarizing laminated film, and was 2nd. The same applies when obtaining a polarizing plate. There is no restriction | limiting in particular in the order of the process of taking out a 1st polarizing plate from a polarizing laminated film, and the process of taking out a 2nd polarizing plate.

The polarizing plate produced as described above can be used as an optical film in which other optical layers are laminated in practical use. Moreover, the said protective film may have a function of these optical layers. As another optical layer, a reflective polarizing film that transmits a certain kind of polarized light and reflects polarized light having the opposite properties; a film with an antiglare function having an uneven shape on the surface; a film with a surface antireflection function A reflective film having a reflective function on the surface; a transflective film having both a reflective function and a transmissive function; and a viewing angle compensation film.

For example, “DBEF” (available from 3M, Sumitomo 3M Co., Ltd.) can be used as a commercial product equivalent to a reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties. ), “APF” (manufactured by 3M, available from Sumitomo 3M Limited).

Examples of the viewing angle compensation film include an optical compensation film in which a liquid crystal compound is applied to the substrate surface and oriented, a retardation film made of a polycarbonate resin, and a retardation film made of a cyclic polyolefin resin.

Commercially available products corresponding to an optical compensation film coated with a liquid crystal compound on the substrate surface are "WV film" (manufactured by FUJIFILM Corporation), "NH film" (Shin Nippon Oil Co., Ltd.) And “NR Film” (manufactured by Nippon Oil Corporation).

Commercial products corresponding to retardation films made of cyclic polyolefin resin include “Arton Film” (manufactured by JSR Corporation), “Essina” (manufactured by Sekisui Chemical Co., Ltd.), “Zeonor Film” (Nippon Zeon ( Etc.).

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
(1) Production of substrate film Propylene / ethylene random copolymer (Sumitomo Chemical Co., Ltd. “Sumitomo Noblene W151”, melting point Tm = 138 ° C.) containing about 5% by weight of ethylene units on both sides of a resin layer A three-layer base film roll (long base film) having a resin layer made of homopolypropylene (Sumitomo Chemical Co., Ltd. “Sumitomo Nobrene FLX80E4”, melting point Tm = 163 ° C.), which is a propylene homopolymer Was manufactured by coextrusion molding using a multilayer extrusion molding machine. The total thickness of the base film was 100 μm, and the thickness ratio (FLX80E4 / W151 / FLX80E4) of each layer was 3/4/3.

(2) Formation of Primer Layer and Polyvinyl Alcohol Resin Layer Polyvinyl alcohol powder (“Z-200” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree 1100, average saponification degree 99.5 mol%) is 95 ° C. It melt | dissolved in hot water and prepared polyvinyl alcohol aqueous solution with a density | concentration of 3 weight%. The resulting aqueous solution was mixed with 5 parts by weight of a crosslinking agent (“SUMILES RESIN 650” manufactured by Sumitomo Chemical Co., Ltd.) with respect to 6 parts by weight of polyvinyl alcohol powder to obtain a primer layer coating 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 hot water at 95 ° C. to obtain a polyvinyl alcohol having a concentration of 8% by weight. An aqueous alcohol solution was prepared.

Next, while continuously unwinding the base film from the base film roll obtained in the above (1), the both sides of the base film are subjected to corona treatment, and then the corona treatment is performed on both surfaces using the gravure coater. A film having a primer layer with a thickness of 0.2 μm on both sides was prepared by continuously applying the coating liquid for application and drying at 80 ° C. for 10 minutes.

Subsequently, while transporting the film, the polyvinyl alcohol aqueous solution was continuously applied onto the primer layers on both sides using a comma coater and dried at 80 ° C. for 5 minutes to obtain a thickness of 10. A 6 μm polyvinyl alcohol resin layer was formed. Under the present circumstances, the part of 1 cm is made into the uncoated area | region which does not apply polyvinyl alcohol aqueous solution to the inside from the width direction both ends of a base film, respectively. This film was once wound up into a roll.

(3) Production of stretched film While unwinding the film continuously from the film roll obtained in (2) above, the uncoated area of the polyvinyl alcohol-based resin layer is continuously formed by a slit method using a leather blade. Cut and removed, followed by free end uniaxial stretching at a magnification of 5.8 times in the longitudinal direction (film transport direction) at a stretching temperature of 160 ° C. using an inter-roll air stretching device to form a stretched film with a thickness of 65.5 μm, This was wound up to obtain a stretched film roll.

(4) Production of Polarizing Film While continuously stretching the stretched film from the stretched film roll obtained in (3) above, the stretched film is applied to a dyeing solution at 30 ° C. containing iodine and potassium iodide for about 150 seconds. The polyvinyl alcohol-based resin layer was dyed so as to have a dwell time of 1, 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 as to have a residence time of about 600 seconds. Thereafter, it was washed with pure water at 10 ° C. for 4 seconds and dried at 80 ° C. for 300 seconds to obtain a polarizing film having a polarizer layer, which was wound up to obtain a polarizing film roll.

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

Next, the polarizing film is continuously unwound from the polarizing film roll obtained in the above (4), and the first protective film [transparent protective film composed of triacetylcellulose (TAC) (TAC) ( Konica Minolta Opto Co., Ltd. “KC4UY”)] was continuously unwound from the second protective film roll. Subsequently, after the saponification treatment is performed on the bonding surfaces of the first and second protective films, the first protective film is provided on one surface of the polarizing film, the second protective film is provided on the other surface, and both protective films. It laminates | stacks, supplying the said adhesive solution between polarizer layers (feed), and it crimps | bonds by passing a laminated body between a pair of bonding rolls, and performs the continuous bonding of the 1st and 2nd protective film. It was.

As a 1st and 2nd protective film, what is 8.0 cm wider than a polarizing film is used, and the width direction center of a 1st and 2nd protective film and the width direction center of a polarizing film correspond. (Thus, the first and second protective films protruded 4.0 cm outward from the polarizing film at both ends in the width direction).

Moreover, at the time of pasting, both width direction both ends of both adhesive layers are located outside the width direction both ends of the polarizing film, respectively, and so as to be located inside the width direction both ends of the first and second protective films, The supply amount of the adhesive solution on both sides was adjusted.

Subsequently, the film was dried at 80 ° C. for 5 minutes to obtain a polarizing laminated film, which was wound up to obtain a polarizing laminated film roll. This polarizing laminated film is composed of nine layers: first protective film / adhesive layer / polarizer layer / primer layer / base film / primer layer / polarizer layer / adhesive layer / second protective film.

The obtained polarizing laminated film was in a good state with no sticking out of the adhesive from the end of the film and adhesion of the adhesive to the outer surfaces of the first and second protective films. Moreover, the contamination by the adhesive was not recognized also about the bonding roll.

(6) Production of polarizing plate While the polarizing laminated film is continuously unwound from the polarizing laminated film roll obtained in (5) above, the first protective film and the second protective film are directly bonded by the adhesive layer. The part which was made was cut and removed continuously by the slit method using a leather blade.

Subsequently, the base film was continuously peeled and removed at the base film / primer layer interface, and “(first or second) protective film / adhesive layer / Two polarizing plates having a configuration of “polarizer layer / primer layer” were obtained. When the base film is peeled off, at any base film / primer layer interface, the above angles θ, φp, and φk at the peeling point between the base film and the polarizing plate are 0 degree, 0 degree, and 45 degrees, respectively. The degree. The base film could be peeled relatively easily.

<Comparative Example 1>
A polarizing film roll was produced by the method described in Example 1 (1) to (4).

The polarizing film is continuously unwound from the polarizing film roll, and the first protective film from the first protective film roll [transparent protective film made of triacetyl cellulose (TAC) ("KC4UY" manufactured by Konica Minolta Opto Co., Ltd.) The second protective film [same as the first protective film] was continuously unwound from the second protective film roll. Subsequently, after the saponification treatment is performed on the bonding surfaces of the first and second protective films, the first protective film is provided on one surface of the polarizing film, the second protective film is provided on the other surface, and both protective films. It laminates | stacks, supplying (feed) the same adhesive agent solution as what was used in Example 1 between the polarizer layers, and it crimps | bonds by passing a laminated body between a pair of bonding rolls, and the 1st and 2nd The protective film was continuously bonded.

As a 1st and 2nd protective film, the thing of the same width as a polarizing film was used, and it bonded so that the width direction center of a 1st and 2nd protective film and the width direction center of a polarizing film might correspond ( Therefore, the end surfaces of the first and second protective films coincide with the end surfaces of the polarizing film).

In addition, at the time of bonding, the supply amount of the adhesive solution on both sides was adjusted so that the adhesive was spread over the entire bonding surface of the polarizing film. However, despite the adjustment of the supply amount of the adhesive solution, the adhesive rolls out little by little from the end in the film width direction due to the meandering of the film during transportation and fluctuations in the supply amount of the adhesive solution. I got stuck to it. When the film was bonded to several tens of meters, the adhesive attached to the bonding roll began to be transferred to the outer surfaces of the first and second protective films, and the contamination on the surfaces began to be noticeable.

Subsequently, the film was dried at 80 ° C. for 5 minutes to obtain a polarizing laminated film having the same layer structure as that of Example 1.

When the adhesive layer of the obtained polarizing laminated film was confirmed, in addition to the portion protruding from the end in the film width direction, despite the adjustment of the supply amount of the adhesive solution as described above, the adhesive layer The part which edge part exists inside the film width direction edge part (namely, part which an adhesive layer does not exist between a polarizer layer and a protective film) was recognized. Due to the difference in drying shrinkage due to such non-uniformity of the adhesive layer, undulation was generated at the widthwise end of the polarizing laminated film.

Next, after winding the polarizing laminated film into a roll shape, when the polarizing laminated film is unwound, the adhesive film transferred to the outer surface of the protective film causes the films to be in the region of the film edge. At the time of sticking and unwinding, this adhesive cohesively breaks down, leaving a white cohesive failure mark. Moreover, the tension at the time of unwinding was not stable.

Next, when the substrate film was peeled off from the unwound polarizing laminated film, peeling itself was possible, but the peeling direction at the time of peeling changed momentarily due to the waviness of the film edge, and the tension Was not stable and could not be peeled smoothly.

100,600 base film, 110 polarizer layer, 120, 130 uncoated area, 200 first protective film, 250 first adhesive layer, 300 second protective film, 350 second adhesive layer, 500 polarizing laminate Film, 700 1st polarizing plate.

Claims

Polarized light comprising a polyvinyl alcohol resin layer having a dichroic dye adsorbed and oriented on at least one surface of a base film, and having a polarizer layer having the same width as that of the base film or a width narrower than that. A step of preparing a conductive film;
The first protection wider than the polarizing film on the one surface of the polarizing film and on the polarizer layer provided on the one surface of the base film via the first adhesive layer. Disposing a film, disposing a second protective film wider than the polarizing film on the other surface of the polarizing film to obtain a polarizing laminated film,
The width direction both ends of the first and second protective films are located outside the width direction both ends of the polarizing film, and the width direction both ends of the first adhesive layer are respectively width direction both ends of the polarizing film. The manufacturing method of the light-polarizing laminated film which arrange | positions the said 1st and 2nd protective film so that it may be located outside rather than the width direction both ends of the said 1st and 2nd protective film.
After the step of disposing the first and second protective films, the both ends in the width direction of the polarizing laminated film are removed by cutting at the positions at the ends in the width direction of the polarizer layer or at the positions inside thereof. The manufacturing method of the light-polarizing laminated film of Claim 1 which further includes a process.
The step of preparing the polarizing film,
Forming a polyvinyl alcohol-based resin layer by applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film;
Uniaxially stretching a substrate film having a polyvinyl alcohol-based resin layer;
The manufacturing method of the light-polarizing laminated film of Claim 1 including the process of dyeing the polyvinyl-alcohol-type resin layer of the uniaxially stretched film with a dichroic dye, and making it a polarizer layer.
Preparing a polarizing laminate film produced by the method according to claim 2;
Removing the substrate film from the polarizing laminate film to obtain a first polarizing plate in which the first protective film is bonded to the polarizer layer.
The polarizing film includes the polarizer layers on both sides of the base film,
In the step of disposing the first and second protective films, the second protective film has both ends in the width direction of the second adhesive layer on the other surface of the polarizing film via the second adhesive layer. Each of the polarizing films is disposed outside the both ends in the width direction, and disposed inside the both ends in the width direction of the first and second protective films,
The said base film is peeled and removed from the said polarizing laminated film, The said 1st polarizing plate and the 2nd polarizing plate by which the said 2nd protective film was bonded to the said polarizer layer are obtained. Manufacturing method of this polarizing plate.