TW201618921A - Method for producing polarizing laminated film or polarizing plate - Google Patents

Abstract

The method for producing polarizing laminated film contains, in this order, a coating step (S10) of coating an aqueous solution of polyvinyl alcohol resin on a substrate film to obtain a coating film, a drying step (S20) of drying the coating film to obtain a laminating with the polyvinyl alcohol resin layer formed on the substrate film, an elongation step (s30) for conducting a single axis elongation to the laminated film to obtain an elongated laminated film, and a dyeing step (S40) for dyeing the polyvinyl resin layer into polarizing layer to obtain polarizing laminated film. Wherein, the elongation step (30) is conduct by starting the single axis elongation while the water content of the laminated film is 0.3 mass % or more.

Description

Polarizing laminated film or method for producing polarizing plate

The present invention relates to a method for producing a polarizing laminate film or a polarizing plate.

The polarizing plate is widely used as a supply element for polarizing light of a display device such as a liquid crystal display device. As such a polarizing plate, a protective film made of cellulose triacetate is used in the case of a polarizing film (polarizing sheet layer) made of a polyvinyl alcohol-based resin, but in recent years, a liquid crystal display device has been used. It has been required to reduce the thickness of thin-walled computers, such as portable computers such as notebook computers and mobile phones.

In the prior art, a film made of a polyvinyl alcohol-based resin is separately stretched, or a dyeing process and a cross-linking process are applied to form a polarizing film, and a polarizing film is produced by laminating it on a protective film or the like. However, it can only be thinned to the thickness of the polarizing film alone. On the other hand, a method of making the thickness of the polarizer layer (polarizing film) thinner than before is known (for example, refer to Patent Document 1), which is a polyethylene which is provided as a polarizing layer on the surface of the base film. After the alcohol-based resin layer, the base film and the polyvinyl alcohol-based resin layer are stretched and dyed/crosslinked. In the step and the subsequent drying step, the polyvinyl alcohol-based resin layer is used as a polarizer layer, and can be thinned to the total thickness limit of the base film and the polarizer layer.

Prior technical literature Patent literature

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-93074

An object of the present invention is to provide a polyvinyl alcohol-based resin layer on the surface of a base film, and then to extend the polyvinyl alcohol-based resin layer together with the base film and dye it. In the cross-linking step and the subsequent drying step, the polyvinyl alcohol-based resin layer is used as a polarizing plate layer, and a method for producing a polarizing laminated film having a thin polarizing film layer can be produced, and a polarizing film having a polarizing layer can be produced. A method of laminating a film, and the polarizer layer has excellent optical properties.

The present invention encompasses the following matters.

[1] A method for producing a polarizing laminated film, comprising: a coating step of applying a solution of a polyvinyl alcohol-based resin to a base film to obtain a coated film; and a drying step of drying the coating The film is dried to obtain a laminated film in which a polyvinyl alcohol-based resin layer is formed on the base film; the extending step is to uniaxially stretch the laminated film to obtain an extended laminated film; and a dyeing step of the polyethylene The alcohol resin layer is dyed and set In the polarizing layer, a polarizing laminated film is obtained, and in the extending step, the uniaxial stretching is started in a state where the moisture content of the laminated film is 0.3% by mass or more.

[2] The method for producing a polarizing laminated film according to [1], wherein the drying step is performed so that the average moisture content change of the coating film is 5 to 65% by mass/minute.

[3] The method for producing a polarizing laminated film according to [1], wherein after the drying step, the moisture content of the laminated film is adjusted to 0.3% by mass or more. In the wet step, the laminated film after the humidity is adjusted in the humidity control step is supplied to the stretching step while maintaining the moisture content.

[4] A method for producing a polarizing laminated film, comprising: a first coating step of applying a solution of a polyvinyl alcohol-based resin to one surface of a base film to obtain a coated film; and first drying a step of drying the coating film to obtain a laminated film having a polyvinyl alcohol-based resin layer formed on one surface of the base film, and a second coating step of coating the other side of the base film a double-coated film is obtained by using an aqueous solution of a vinyl alcohol resin; and a second drying step of drying the double-coated film to obtain a two-layer film having a polyvinyl alcohol-based resin layer formed on both surfaces of the base film; and an extending step a uniaxially extending the two-layer film to obtain an extended laminated film; and a dyeing step of the polyvinyl alcohol-based resin The layer is dyed to form a polarizing layer to obtain a polarizing laminated film, and the extending step is to start the uniaxial stretching in a state where the water content of the two-area film is 0.5% by mass or more.

[5] The method for producing a polarizing laminated film according to the above aspect, wherein the first drying step is performed such that the moisture content of the laminated film after drying is 0.3% by mass or more.

[6] The method for producing a polarizing laminate film according to [4], wherein the first drying step and the second drying step are an average moisture content change of the coating film and the two-side coating. The change in the average moisture content of the cloth film was carried out in a manner of 5 to 65% by mass/minute.

The method for producing a polarizing laminated film according to any one of the aspects of the present invention, wherein after the second drying step, the water content of the two-layer film is 0.5% by mass or more The humidity adjustment step is performed, and the two-layer film after the humidity adjustment step is provided to the extending step while maintaining the moisture content.

[8] A method of producing a polarizing plate, comprising the steps of: producing a polarizing laminated film according to the manufacturing method according to any one of [1] to [7]; a step of bonding a protective film to the surface of the polarizer layer in the film opposite to the base film to obtain a multilayer film; and peeling the base film from the multilayer film to obtain a step of peeling off the polarizing plate layer and the polarizing plate of the protective film.

In the present invention, by controlling the value of the moisture content of the laminated film supplied to the stretching step, it is possible to provide a polarizing laminated film having a polarizing plate layer having excellent optical properties.

S10‧‧‧ Coating step

S11‧‧‧1st coating step

S12‧‧‧2nd coating step

S20‧‧‧ drying step

S21‧‧‧1st drying step

S22‧‧‧2nd drying step

S30, S31‧‧‧ extension steps

S40‧‧‧Staining step

S50‧‧‧Finishing steps

S60‧‧‧ peeling step

Fig. 1 is a flow chart showing a method of producing a polarizing laminate film and a polarizing plate according to the first embodiment.

Fig. 2 is a flow chart showing a method of producing a polarizing laminate film and a polarizing plate according to the second embodiment.

In the present specification, a laminate having a polyvinyl alcohol-based resin layer (a layer composed of a polyvinyl alcohol-based resin) as a base film is referred to as a "laminated film", and the surfaces of both base films are aggregated. The laminated film of the vinyl alcohol-based resin layer is called a "two-area layer film".

In addition, a polyvinyl alcohol-based resin layer having a function as a polarizer is referred to as a "polarizer layer", and a laminate having a polarizer layer on a base film is referred to as a "polarized laminated film", and will be referred to as a polarizing layer. The laminated body having the protective film on at least one side is called a "polarizing plate". Hereinafter, each constituent element of the polarizing laminated film and the polarizing plate will be described first, and then the manufacturing method will be described.

<Polarizing laminated film and polarizing plate>

[Substrate film]

As the resin used for the base film, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, and elongation can be used, and the glass transition temperature (Tg) or melting point (Tm) can be used. And choose the right resin. Specific examples of the thermoplastic resin include a polyolefin resin, a polyester resin, a cyclic polyolefin resin (northene-based resin), a (meth)acrylic resin, a cellulose ester resin, and a polycarbonate. Ester resin, polyvinyl alcohol resin, vinyl acetate resin, polyarylate resin, polystyrene resin, polyether oxime resin, polyfluorene resin, polyamine resin, polyimine Resins, and such mixtures, copolymers, and the like.

The base film may be a film composed only of the above-mentioned type of resin 1 or a film obtained by blending two or more kinds of resins. The substrate film may be a single layer film or a multilayer film.

Examples of the polyolefin-based resin include polyethylene, polypropylene, and the like, and these are preferably easily and stably extended at a high rate. Further, a propylene-ethylene copolymer or the like obtained by copolymerizing propylene with ethylene can also be used. The copolymerization system may be a monomer other than ethylene, and examples of other types of monomers copolymerizable with propylene include an α-olefin. As the α-olefin, an α-olefin having 4 or more carbon atoms can be suitably used, and an α-olefin having 4 to 10 carbon atoms is preferable. Specific examples of the α-olefin having 4 to 10 carbon atoms include straight 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, and the like. Chain monoolefins; branched monoolefins such as 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene; vinylcyclohexane, etc. . a copolymer of propylene and other monomers capable of copolymerizing therewith, which may be The random copolymer may also be a block copolymer. In the copolymer, the content of the constituent unit derived from the other monomer can be infrared (IR) according to the method described on page 616 of the "Handbook of Polymer Analysis" (1995, issued by Kiyoshiya Shoten). Spectrometry is used to determine.

Among the above, as the propylene resin constituting the propylene resin film, a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, and propylene-ethylene-1- are preferably used. Butylene random copolymer.

Moreover, the stereoregularity of the propylene-based resin constituting the propylene-based resin film is preferably substantially the same or the same. The propylene-based resin film composed of a propylene-based resin having a substantially uniform or uniform stereoregularity has a relatively good handleability and excellent mechanical strength in a high-temperature environment.

The polyester resin is a polymer having an ester bond, and is mainly a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. The polycarboxylic acid to be used is mainly a dicarboxylic acid, that is, a divalent carboxylic acid, or a lower alkyl ester thereof, for example, citric acid, isodecanoic acid, dimethyl phthalate, naphthalene dicarboxylic acid Methyl ester, etc. Further, the polyol to be used is mainly a diol, that is, a divalent alcohol, and examples thereof include propylene glycol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Specific examples of the resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, propylene terephthalate, and polynaphthalene. Propylene dicarboxylate, polycyclohexane anti-dimethyl phthalate, dimethyl polycyclohexane naphthalate, and the like. These blended resins and copolymers can also be suitably used.

As the cyclic polyolefin resin, it is preferable to be suitable A decene-based resin is used. The cyclic polyolefin-based resin is a general term for a resin which is polymerized by using a cyclic olefin as a polymerization unit, and the like, for example, JP-A No. 1-240517, JP-A No. 3-148882, and JP-A No. 3-122137 The resin described. Specific examples thereof include a ring-opened (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and a copolymer of a cyclic olefin and an α-olefin such as ethylene or propylene (typically a random copolymer). And a graft polymer modified with an unsaturated carboxylic acid and a derivative thereof, and the like, and the like. Specific examples of the cyclic olefin include a norbornene-based monomer.

As the cyclic polyolefin resin, various commercially available products are available. Specific examples include TOPAS (registered trademark) (manufactured by Topas Advanced Plymers GmbH), ARTON (registered trademark) (manufactured by JSR), and ZEONOR (ZEONOR) (registered trademark) (manufactured by Japan ZEON Co., Ltd.). ZEONEX (ZEONEX) (registered trademark) (Japan ZEON Co., Ltd.), APEL (registered trademark) (Mitsui Chemical Co., Ltd.).

Any suitable (meth)acrylic resin can be used as the (meth)acrylic resin. For example, polymethacrylate such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth) acrylate copolymer, and methacrylic acid are mentioned. Methyl ester-acrylate-(meth)acrylic acid copolymer, methyl methacrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-(methyl) A cyclohexyl acrylate copolymer, a methyl methacrylate-(meth)acrylic acid thiol based copolymer, etc.). Preferably, a polymer such as polymethyl methacrylate or the like having a C ₁ -C ₆ alkyl methacrylate as a main component is used. As the (meth)acrylic resin, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is preferably used.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of such a cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, a product obtained by modifying a part of the copolymer or the hydroxyl group with another type of substituent or the like may be mentioned. Among these, cellulose triacetate is particularly preferred. Cellulose triacetate is commercially available in many products and is advantageous in terms of ease of use and cost. As an example of a commercial product of cellulose triacetate, FUJITAC (registered trademark) TD80 (Fuji FILM Co., Ltd.), FUJITAC (registered trademark) TD80UF (Fuji FILM Co., Ltd.), FUJITAC (registered trademark) TD80UZ (Fuji FILM Co., Ltd.), FUJITAC (registered trademark) TD40UZ (Fuji FILM Co., Ltd.), KC8UX2M (Konica Minolta Co., Ltd.), KC4UY (Konica Minolta Co., Ltd.), and the like.

The polycarbonate resin is an engineering plastic composed of a polymer obtained by bonding a monomer unit through a carbonate group, and is a resin having high impact resistance, heat resistance, and flame retardancy. Moreover, since it has high transparency, it can also be suitably used for optical use. For optical use, there are also commercially available resins which are modified by a polymer skeleton to reduce the photoelastic modulus and which are called modified polycarbonates; and copolymerized polycarbonates which have improved wavelength dependence. These systems are suitable for use. Such a polycarbonate resin is widely commercially available, and for example, PANLITE (registered trademark) (Emperor) Chemical (share)), UPILON (registered trademark) (Mitsubishi Engineering Plastics Co., Ltd.), SD POLYCA (registered trademark) (Sumitomo Dow (share)), CALIBRE (registered trademark) (Dow Chemical).

The base film may be added with any appropriate additives in addition to the above thermoplastic resin. Examples of such an additive include an ultraviolet absorber, an antioxidant, a slip agent, a plasticizer, a mold release agent, a coloring preventive agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a color former. The content of the above-exemplified thermoplastic resin in the base film is preferably from 50 to 100% by weight, preferably from 50 to 99% by weight, more preferably from 60 to 98% by weight, particularly preferably from 70 to 97% by weight. . When the content of the thermoplastic resin in the base film is less than 50% by weight, the thermoplastic resin may not sufficiently exhibit the high transparency and the like originally possessed.

The thickness of the base film before stretching can be appropriately determined. In terms of workability such as strength and workability, the moisture content of the laminated film in which the polyvinyl alcohol-based resin layer is formed on the base film is adjusted in the present invention. The thickness of the base film is preferably 50 to 200 μm, more preferably 70 to 130 μm. Moreover, the melting point of the base film or the glass transition temperature is preferably a high value from the temperature range of the drying step and the stretching step which will be described later. By using such a base film, it is possible to prevent the base material from being too soft in the drying step and the stretching step, and it is possible to prevent the in-plane film thickness distribution of the polyvinyl alcohol-based resin layer from being deteriorated.

The base film may be subjected to corona treatment, plasma treatment, flame treatment or the like on the surface on the side on which at least the polyvinyl alcohol-based resin layer is formed in order to improve the adhesion to the polyvinyl alcohol-based resin layer. Also, in order to increase the density Further, a thin layer such as a primer layer or an adhesive layer may be formed on the surface of the base film on the side on which the polyvinyl alcohol-based resin layer is formed.

(primer layer)

When the base film is formed on the surface of the base film on the side where the polarizer layer is formed, the primer layer is required to have a certain degree of denseness to both the base film and the polyvinyl alcohol resin layer. There is no particular limitation on the material to be used. For example, a thermoplastic resin having excellent transparency, thermal stability, and elongation can be used. Specifically, an acrylic resin or a polyvinyl alcohol-based resin may be mentioned, but it is not limited to these. Among them, a polyvinyl alcohol-based resin having a good adhesion can be suitably used.

The polyvinyl alcohol-based resin used as the primer layer may, for example, be a polyvinyl alcohol resin or a derivative thereof. Examples of the polyvinyl alcohol resin derivative include, in addition to polyvinyl formaldehyde and polyvinyl acetal, an olefin such as ethylene or propylene, or an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or crotonic acid. An alkyl ester of an unsaturated carboxylic acid, acrylamide or the like is obtained by modifying a polyvinyl alcohol resin. Among the above polyvinyl alcohol-based resin materials, a polyvinyl alcohol resin is preferably used.

In order to increase the strength of the primer layer, a crosslinking agent may also be added to the above thermoplastic resin. As the crosslinking agent to be added to the thermoplastic resin, those known as organic or inorganic can be used. It is sufficient to appropriately select the thermoplastic resin to be used. For example, in addition to a low molecular crosslinking agent such as an epoxy crosslinking agent, an isocyanate crosslinking agent, a dialdehyde crosslinking agent, or a metal clamp crosslinking agent, it is also possible to use methylolated melamine. A polymer-based crosslinking agent such as an amine resin or a polyamide resin. When a polyvinyl alcohol-based resin is used as the thermoplastic resin, it is particularly preferable to use a polyamide solvent, a methylolated melamine, a dialdehyde, a metal chelating agent crosslinking agent or the like as a crosslinking agent.

The thickness of the primer layer is preferably from 0.05 to 1 μm, more preferably from 0.1 to 0.4 μm. When it is thinner than 0.05 μm, the adhesion between the base film and the polyvinyl alcohol-based resin layer is lowered, and if it is thicker than 1 μm, the polarizing plate becomes thick, which is not preferable.

[Polarized film layer]

Specifically, the polarizer layer is obtained by adsorbing a dichroic dye to an extended polyvinyl alcohol-based resin layer.

The polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin layer can be obtained by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and another monomer copolymerizable, in addition to polyvinyl acetate of a homopolymer of vinyl acetate. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The polyvinyl alcohol-based resin constituting the polarizer layer (polyvinyl alcohol-based resin layer) is preferably a completely saponified product. The degree of saponification is preferably in the range of 80.0 mol% to 100.0 mol%, preferably in the range of 90.0 mol% to 99.5 mol%, and preferably in the range of 94.0 mol% to 99.0 mol%. When the degree of saponification is less than 80.0 mol%, after being used as a polarizing plate, it is water resistant/ A bad condition in which the heat and humidity resistance is remarkably deteriorated. Further, when a polyvinyl alcohol-based resin having a degree of saponification of more than 99.5 mol% is used, the dyeing speed is remarkably slow, or a polarizing laminated film having sufficient polarizing properties cannot be obtained, and it is produced at the time of production. It is necessary to achieve a bad condition of the dyeing time which is usually several times.

The degree of saponification referred to herein is the ratio of the acetic acid group contained in the polyvinyl acetate-based resin of the raw material of the polyvinyl alcohol-based resin to the hydroxyl group by the saponification step, and the ratio is expressed in units of moles (% by mole). ) The value expressed by the following formula. It can be obtained by the method specified in JIS K 6726 (1994).

Degree of saponification (% by mole) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100

The higher the degree of saponification, the higher the proportion of the hydroxyl group, that is, the lower the proportion of the acetate group which hinders crystallization.

Further, the polyvinyl alcohol-based resin used in the present invention may be a partially modified polyvinyl alcohol. For example, an olefin such as ethylene or propylene, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, an alkyl ester of an unsaturated carboxylic acid, or acrylamide may be used to modify a polyvinyl alcohol resin. Wait. The modified ratio is preferably less than 30 mol%, preferably less than 10 mol%. When the modification is more than 30 mol%, it is difficult to adsorb the dichroic dye and the polarizing performance is lowered.

The average degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, and is preferably from 100 to 10,000, more preferably from 1,500 to 8,000, and most preferably from 2,000 to 5,000. The average degree of polymerization here is also used in JIS. The value obtained by the method specified in K 6726 (1994).

Examples of the polyvinyl alcohol-based resin having such a property include PVA124 (saponification degree: 98.0 to 99.0 mol%) manufactured by KURARAY, PVA117 (saponification degree: 98.0 to 99.0 mol%), and PVA624 (for example). Saponification degree: 95.0 to 96.0 mol%) and PVA617 (saponification degree: 94.5 to 95.5 mol%); for example, AH-26 (saponification degree: 97.0 to 98.8 mol%) manufactured by Nippon Synthetic Chemical Industry Co., Ltd., AH -22 (saponification degree: 97.5 to 98.5 mol%), NH-18 (saponification degree: 98.0 to 99.0 mol%), and N-300 (saponification degree: 98.0 to 99.0 mol%); for example, Japan VAM & POVAL JC-33 (saponification degree: 99.0 mol% or more), JM-33 (saponification degree: 93.5 to 95.5 mol%), JM-26 (saponification degree: 95.5 to 97.5 mol%), JP- 45 (saponification degree: 86.5-89.5 mol%), JF-17 (saponification degree: 98.0-99.0 mol%), JF-17L (saponification degree: 98.0-99.0 mol%), and JF-20 (saponification degree) : 98.0 to 99.0 mol%), etc., can be suitably used in the present invention.

By using such a polyvinyl alcohol-based resin as an aqueous solution, it can be applied onto a base film and dried to form a polyvinyl alcohol-based resin layer.

Such a polyvinyl alcohol-based resin layer is stretched and aligned at the same time as the base film, and further the dichroic dye is adsorbed and aligned to form a polarizer layer. The stretching ratio is preferably more than 5 times, more preferably more than 5 times and 17 times or less.

The thickness of the polarizer layer (thickness of the polyvinyl alcohol-based resin layer after stretching) is 10 μm or less, preferably 7 μm or less. By setting the thickness of the polarizer layer to 10 μm or less, a thin polarizing plate can be formed.

Examples of the dichroic dye used in the polarizer layer include iodine, an organic dye, and the like. As the organic dye, for example, RED BR, RED LR, RED R, PINK LB, RUPINE BL, BORDEAUX GS, SKYBLUE LG, LEMON YELLOW, BLUE BR, BLUE 2R, NAVY RY, GREEN LG, VIOLET LB, VIOLET B, BLACK can be used. H, BLACK B, BLACK GSP, YELLOW 3G, YELLOW R, ORANGE LR, ORANGE 3R, SCARLET GL, SCARLET KGL, CONGO RED, BRILLIANT VIOLET BK, SUPRA BLUE G, SUPRA BLUE GL, SUPRA ORANGE GL, DIRECT SKYBLUE, DIRECT FAST ORANGE S, FAST BLACK, etc. These dichroic substances may be one type or two or more types may be used in combination.

[protective film]

The protective film may be only a protective film having no optical function, or may be a protective film having both optical functions of a retardation film and a brightness enhancement film.

The material of the protective film is not particularly limited, and examples thereof include a cyclic polyolefin resin film, a cellulose acetate resin film composed of a resin of cellulose triacetate or cellulose diacetate, and a like. A polyester resin film, a polycarbonate resin film, an acrylic resin film, and a polypropylene resin film which are composed of a resin of ethylene phthalate, polyethylene naphthalate, and polybutylene terephthalate. Such films that were previously widely used in the field.

As a cyclic polyolefin resin, a suitable commercial product can be suitably used, for example, TOPAS (registered trademark) (Topas Advanced) Manufactured by Polymers GmbH, ARTON (registered trademark) (JSR), ZEONOR (trademark) (Japan ZEON), ZEONEX (registered trademark) (ZEONEX) (Japan ZEON) ), APEL (registered trademark) (Mitsui Chemical Co., Ltd.). When such a cyclic polyolefin resin is formed into a film, a well-known method such as a solvent casting method or a melt extrusion method can be suitably used. In addition, it is also possible to use S-SINA (registered trademark) (made by Sekisui Chemical Co., Ltd.), SCA40 (made by Sekisui Chemical Industry Co., Ltd.), ZEONOR (registered trademark) film (made by Japan ZEON Co., Ltd.), etc. A commercially available product of a film made of a film of a cyclic polyolefin resin.

The cyclic polyolefin resin film may be uniaxially stretched or biaxially stretched. By extending, it is possible to impart an arbitrary retardation value to the cyclic polyolefin-based resin film. The stretching is usually carried out continuously while winding up the film roll, and is extended by the heating furnace in the direction in which the roll is proceeding, the direction perpendicular thereto, or both. The temperature of the heating furnace is usually in the range from the vicinity of the glass transition temperature of the cyclic polyolefin resin to the glass transition temperature + 100 °C. The stretching ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times, in each direction.

Since the cyclic polyolefin resin film is generally inferior in surface activity, the surface treatment with the plasma film, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment, etc. is performed on the surface adjacent to the polarizing film. good. In particular, it is preferable to perform plasma treatment and corona treatment which can be carried out relatively easily.

As a cellulose acetate-based resin film, a suitable commercial product can be suitably used, for example, FUJITAC (registered trademark) TD80 (Fuji FILM Co., Ltd.) System), FUJITAC (registered trademark) TD80UF (Fuji FILM (share) system), FUJITAC (registered trademark) TD80UZ (Fuji FILM (share) system), FUJITAC (registered trademark) TD40UZ (Fuji FILM (share) system), KC8UX2M ( Konica Minolta Co., Ltd., KC4UY (Konica Minolta Co., Ltd.).

A liquid crystal layer or the like for improving the viewing angle characteristics may be formed on the surface of the cellulose acetate resin film. Further, in order to impart a phase difference, the cellulose acetate resin film may be stretched. In order to improve the adhesion to the polarizing film, the cellulose acetate resin film is usually subjected to a saponification treatment. As the saponification treatment, a method such as immersion in an aqueous solution of a base of sodium hydroxide and potassium hydroxide can be employed.

An optical layer such as a hard coat layer, an antiglare layer, or an antireflection layer can be formed on the surface of the protective film as described above. The method of forming these optical layers on the surface of the protective film is not particularly limited, and a well-known method can be used.

The thickness of the protective film is preferably as small as possible from the viewpoint of thinning, preferably 90 μm or less, and preferably 50 μm or less. On the other hand, if it is too thin, the workability is inferior because of the decrease in strength, and it is preferably 5 μm or more.

<Method for Producing Polarizing Laminated Film and Polarizing Plate>

[First Embodiment]

Fig. 1 is a flow chart showing a method of producing a polarizing laminate film and a polarizing plate according to the first embodiment. The system for producing a polarizing laminated film according to the first embodiment The manufacturing method includes, in order, a coating step (S10) of applying a polyvinyl alcohol-based resin aqueous solution to one side of a base film to obtain a coated film, and a drying step (S20) of drying the coated film. a laminated film in which a polyvinyl alcohol-based resin layer is formed on a base film; an extending step (S30) of uniaxially stretching the laminated film to obtain an extended laminated film; and a dyeing step (S40) The polyvinyl alcohol-based resin layer is dyed to form a polarizing plate layer to obtain a polarizing laminated film.

In order to manufacture a polarizing plate, a bonding step (S50) may be further included in which a transparent protective film is bonded to a surface of the polarizing laminated film on which the polarizing layer is opposite to the base film. a multilayer film; and a peeling step (S60) of peeling the base film from the multilayer film to obtain a polarizing plate including the polarizer layer and the transparent protective film.

<Production steps>

Hereinafter, each step of S10 to S60 in Fig. 1 will be described in detail.

[Coating step (S10)]

Here, a polyvinyl alcohol-based resin aqueous solution is applied to one surface of a base film to obtain a coated film.

The material suitable for the base film is as described in the description of the constituent elements of the above polarizing laminate film. Also, the substrate film is used It is preferred that it can be extended in a temperature range suitable for the elongation of the polyvinyl alcohol-based resin.

In the coating step (S10), it is preferred to apply a polyvinyl alcohol-based resin solution obtained by dissolving a powder of a polyvinyl alcohol-based resin in a good solvent on the surface of the base film to obtain a coated film. By forming a polyvinyl alcohol-type resin layer by the coating process, a polyvinyl alcohol-type resin can be thinned. As a method of applying the polyvinyl alcohol-based resin solution to the base film, a roll coating method such as a bar coating method, reverse roll coating, gravure coating, or the like, a die coating method, or a doctor blade can be appropriately selected. Well-known methods such as a coating method, a lip coating method, a spin coating method, a screen coating method, a fountain coating method, a dipping method, and a spray method. A knife coater, a die coating method, and a lip coating method are preferred.

After the extension of the stretching step (S30), the thickness of the polyvinyl alcohol-based resin layer extending the laminated film is preferably 10 μm or less. Therefore, the thickness of the resin layer formed by the coating step (S10) and the drying step (S20) is preferably 3 to 50 μm, more preferably 5 to 40 μm. If it is 3 μm or less, it becomes too thin after stretching, so that the dyeability is remarkably deteriorated, which is not preferable. On the other hand, when it is more than 50 μm, the thickness of the finally obtained polarizing plate layer is sometimes larger than 10 μm, which is not preferable.

In order to improve the adhesion between the base film and the polyvinyl alcohol-based resin layer, a primer layer may be provided between the base film and the polyvinyl alcohol-based resin layer. From the viewpoint of adhesion, the primer layer is preferably formed of a composition containing a polyvinyl alcohol-based resin and a crosslinking agent. The material suitable for the primer layer or the like is as described in the description of the constituent elements of the above polarizing laminate film.

[Drying step (S20)]

By drying the coating film obtained in the coating step (S10) and evaporating the solvent of the polyvinyl alcohol-based resin aqueous solution, a laminated film in which a polyvinyl alcohol-based resin layer is formed on the base film can be obtained.

The drying step is preferably carried out so that the average moisture content change of the coating film is 5 to 65% by mass/min, and it is preferably 7.5 to 50% by mass/min, so that it is 7.5 to 30% by mass/ The minute method is better. The change in the average moisture content in the drying step in the present specification means the value obtained by dividing the difference between the moisture content (%) of the coating film at the start of drying and the moisture content (%) of the laminated film at the end of drying by time. . Moreover, the method of calculating the moisture content of the coating film or the laminated film will be described later. When the average moisture content change is more than 65% by mass/min, the drying temperature is required to be increased, which may result in poor dissolution of the base film and discoloration of the polyvinyl alcohol resin. When the average moisture content change is less than 5% by mass/minute, the productivity is deteriorated.

The drying temperature in the drying step is, for example, 50 ° C to 200 ° C, preferably 60 ° C to 150 ° C. The drying method includes a method of blowing hot air, a method of bringing it into contact with a heat roll, and a method of heating by using an IR heater, and any of them can be suitably used. Further, in the drying step, the so-called drying temperature, such as the method of blowing hot air, the case where the drying device of the drying furnace is provided, such as an IR heater, means the ambient temperature in the drying furnace; for example, the contact type drying device of the heat roller In this case, it means the surface temperature of the heat roller. Through the above steps, a laminated film in which a polyvinyl alcohol-based resin layer is formed is produced. The drying time is, for example, 2 minutes to 20 minutes.

[Extension step (S30)]

Here, the laminated film obtained in the drying step (S20) is stretched. In the stretching step (S30), the uniaxial stretching is started in a state where the moisture content of the laminated film in which the polyvinyl alcohol-based resin layer is formed on one surface of the base film is 0.3% by mass or more. When the water content at the start of uniaxial stretching is 0.3% by mass or more, a polarizing laminated film or a polarizing plate having a polarizing plate layer having excellent optical properties can be produced. Moreover, adjusting the water content can be performed, for example, by adjusting the degree of drying in the drying step (S20) or by a humidity control step which will be described later.

The degree of drying in the drying step (S20), in addition to the above drying temperature and drying time, is also in accordance with the thickness (or weight per unit area) of the polyvinyl alcohol-based resin coating layer formed on the substrate film, Since the water concentration, the water vapor pressure, the humidity, and the like in the environment of the drying step are changed, a simple preliminary experiment is performed to obtain a predetermined moisture content (0.3% by mass or more and 3% by mass or less, preferably 0.35% by mass or more. It is sufficient to adjust the conditions in a manner of 1.8% by mass or less. According to circumstances, it is also possible to introduce air adjusted to a predetermined water vapor pressure into the drying furnace. The laminated film which has been dried to a predetermined moisture content in this manner is preferably delivered directly to the stretching step (S30) while maintaining the moisture content. However, it may be delivered after being adjusted to a predetermined moisture ratio by a humidity control step to be described later. The step of extending (S30).

(calculation of moisture content of laminated film)

In the present specification, the moisture content of the laminated film (or coated film) is calculated as follows. First, the mass (A) of the measurement sample was sampled from a laminate film (or a coating film), and then the measurement sample was placed in an oven at 105 ° C for 1 hour. Then, the mass (B) of the measurement sample taken out from the oven was determined. The water content of the laminated film (or the coated film) can be calculated from the following formula (1): the moisture content of the laminated film (or coated film) = (A - B) / A × 100 (%).

(Calculation of moisture content of polyvinyl alcohol-based resin layer)

In the present specification, the water content of the polyvinyl alcohol-based resin layer is a value calculated as follows. First, the laminated film was sampled and the mass (A) of the measurement sample was determined, and then the measurement sample was placed in an oven at 105 ° C for 1 hour. Then, the mass (B) of the measurement sample taken out from the oven was determined. Then, the polyvinyl alcohol-based resin layer was removed from the measurement sample, and the mass (C) of the base film monomer was determined. The water content of the polyvinyl alcohol-based resin layer was calculated according to the following formula (2): the water content of the polyvinyl alcohol-based resin layer = (A - B) / (A - C) × 100 (%).

The water content of the polyvinyl alcohol-based resin layer is preferably 2.5% by mass or more. When the value of the water content of the polyvinyl alcohol-based resin layer is in the above range, cracking of the polyvinyl alcohol-based resin layer after stretching can be suppressed, which is preferable.

In the stretching step (S30), uniaxial stretching is preferably performed so as to be a stretching ratio of more than 5 times and 17 times or less. More preferably, the uniaxial stretching is performed so as to be a stretching ratio of more than 5 times and 8 times or less. When the stretching ratio is 5 times or less, the polyvinyl alcohol-based resin layer is not sufficiently aligned, and as a result, the degree of polarization of the polarizing plate layer is not sufficiently high. On the other hand, when the stretching ratio is more than 17 times, the laminated film at the time of stretching tends to be broken, and the thickness of the extended laminated film after stretching is thinner than necessary, and the workability/operability in the subsequent step is lowered. The extension processing in the extending step (S30) is not limited to a one-stage extension, and can also be performed in multiple stages. In the case of performing in a plurality of stages, the elongation treatment is performed so that the total length of all the stages of the elongation treatment is greater than 5 times.

In the extending step (S30) of the present embodiment, it is possible to perform a longitudinal stretching process for the longitudinal direction of the laminated film, a lateral stretching process for extending the width direction, and the like. Examples of the longitudinal stretching method include a method of extending between rolls, a method of compressing and stretching, and the like, and a tenter stretching method is exemplified as a lateral stretching method.

Further, it is preferred that the elongation treatment of the present invention is carried out by using a dry stretching method. By performing the dry stretching of the polyvinyl alcohol-based resin layer together with the base film before the dyeing step, it is possible to prevent the polyvinyl alcohol-based resin film (polyvinyl alcohol-based resin layer) which is thinner than the conventional one from being broken. The magnification is extended, and the obtained polarizer layer can further reduce the thickness of the polarizing plate.

(conditioning step)

After the drying step (S20), the moisture content of the laminated film may be 0.3% by mass or more and 3% by mass or less, preferably 0.35% by mass or more and 1.8% by mass or less. Adjust humidity. In this case, the laminated film which has been conditioned in the humidity control step is directly supplied to the stretching step (S30) while maintaining the water content of 0.3% by mass or more and 3% by mass or less. The humidity is adjusted in the humidity control step, for example, by placing the laminated film in a room adjusted to an appropriate humidity and temperature; and passing the laminated film through a humidity control furnace adjusted to an appropriate humidity and temperature. Just fine. In the humidity control step, the moisture content can be increased (humidified) according to the state of the laminated film before the film, and the moisture content can be reduced (dried), and the polyvinyl alcohol-based resin layer can be changed without changing the moisture content itself. The form of homogenization.

[Staining step (S40)]

Here, the polyvinyl alcohol-based resin layer of the laminated film is dyed with a dichroic dye. As the dichroic dye system, as described above, iodine and an organic dye can be used.

The dyeing step is performed, for example, by immersing the entire laminated laminated film in a solution (dyeing solution) containing the above-described dichroic dye. As the dyeing solution, a solution obtained by dissolving the above dichroic dye in a solvent can be used. As the solvent of the dyeing solution, water is usually used, and 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 the iodide because the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, cesium iodide, calcium iodide, tin iodide, and titanium iodide. Wait. The addition ratio of the iodides is preferably 0.01 to 20% by weight in the dyeing solution. Among the iodides, potassium iodide is preferably added. When potassium iodide is added, the ratio of iodine to potassium iodide is preferably in the range of 1:5 to 1:100, and preferably in the range of 1:6 to 1:80, at 1:7. The range of 1:70 is particularly good.

The immersion time of the stretched laminated film in the dyeing solution is not particularly limited, and is usually preferably in the range of 15 seconds to 15 minutes, preferably 1 minute to 3 minutes. Further, the temperature of the dyeing solution is preferably in the range of 10 to 60 ° C, and more preferably in the range of 20 to 40 ° C.

In the dyeing step, the dyeing treatment can be carried out immediately after the dyeing. The crosslinking treatment can be carried out, for example, by immersing the laminated film in a solution (crosslinking solution) containing a crosslinking agent. As the crosslinking agent, a previously known substance can be used. For example, a boron compound such as boric acid or borax, glyoxal or glutaraldehyde can be given. These lines may be of one type or may be used in combination of two or more types.

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

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

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

By the above dyeing step (S40), the polyvinyl alcohol-based resin layer functions as a polarizing plate layer, and a polarizing laminated film can be obtained.

[washing step]

Next, it is preferable to carry out a washing step of washing the polarizing laminated film. As a washing step, a water washing treatment can be applied. The water washing treatment system can usually be carried out by immersing the stretched film in pure water such as ion-exchanged water or distilled water. The water washing temperature is usually from 3 to 50 ° C, preferably from 4 ° C to 20 ° C. The immersion time is usually 2 to 300 seconds, preferably 3 seconds to 240 seconds.

The washing step may be a combination of a washing treatment with an iodide solution and a water washing treatment, and a solution of a liquid alcohol prepared with methanol, ethanol, isopropanol, butanol, propanol or the like may be suitably used. Further, after the washing step, a water removing step using a nip roll, an air scraper or the like can also be provided.

After the washing step, it is preferred to dry the polarizing laminate film. In such drying, a drying step comprising a temperature of 60 ° C or higher is preferred, and a drying step comprising a temperature of 70 ° C or higher is preferred. Of course, it is also possible to include a plurality of stages of drying steps having different temperatures. In this case, any one of the plurality of drying steps may be 60 ° C or higher.

In addition to the temperature, in order to enhance the drying force, it is also possible to optimize the circulation method of the hot air such as the air volume and the wind direction, or to provide an IR heater that locally applies heat. With such assistance, the drying efficiency is further improved, which contributes to productivity improvement.

The upper limit of the drying temperature is preferably a temperature lower than the boiling point of water and preferably less than 100 °C. Further, it is preferably 95 ° C or less, and preferably 90 ° C or less.

[Finishing step (S50)]

Here, the polarizing film layer of the polarizing laminated film which has undergone the above-mentioned process is the surface opposite to the base film, and the laminated film is bonded together, and the multilayer film is obtained. As a method of bonding the polarizer layer and the protective film, a method of bonding the polarizer layer and the protective film through the adhesive layer and the adhesive layer can be mentioned. A material suitable as a protective film is as described in the description of the constituent elements of the polarizing plate described above.

(adhesive layer)

The adhesive constituting the adhesive layer is usually an acrylic resin, a styrene resin, a polyoxymethylene resin or the like as a matrix polymer, and a crosslinking agent such as an isocyanate compound, an epoxy compound or an anthracycline compound is added thereto. The composition of the composition. Further, it is also possible to form fine particles in the adhesive to form an adhesive layer which exhibits light scattering properties.

The thickness of the adhesive layer is preferably from 1 to 40 μm, and it is preferably applied in a thin range without impairing the properties of workability and durability. Good for 3~25μm. When it is 3 to 25 μm, it has good workability, and it is also a suitable thickness in terms of suppressing dimensional change of the polarizing film. When the adhesive layer is less than 1 μm, the adhesiveness is lowered. When the adhesive layer is more than 40 μm, the adhesive tends to cause defects such as extrusion.

The method of forming the pressure-sensitive adhesive layer on the protective film and the polarizer is not particularly limited, and a solution containing each component including the above-mentioned matrix polymer may be applied to the surface of the protective film or the surface of the polarizer to be dried to form an adhesive. After the layer is bonded to the separator and other types of films, an adhesive layer may be formed on the separator, and then adhered to the surface of the protective film or the layer of the polarizer to laminate. Further, when the adhesive layer is formed on the protective film or the polarizer layer, one or both of the protective film or the polarizer layer or the adhesive layer may be subjected to a close treatment such as corona treatment as necessary.

(adhesive layer)

The water-based adhesive agent using a polyvinyl alcohol-based resin aqueous solution and an aqueous two-liquid urethane-based emulsion adhesive is used as an adhesive agent which comprises an adhesive agent layer. Among them, a polyvinyl alcohol-based resin aqueous solution can be suitably used. In addition to the vinyl alcohol-based polymer obtained by saponifying the polyvinyl acetate of the homopolymer of vinyl acetate, vinyl acetate-based resin is used as an adhesive, and vinyl acetate can also be used together. A vinyl alcohol-based copolymer obtained by subjecting a copolymer of another monomer to be polymerized to a saponification treatment, and a modified polyvinyl alcohol-based polymer obtained by partially modifying the hydroxyl group. A water-based adhesive may also be added with a polyvalent aldehyde, a water-soluble epoxy compound, a melamine-based compound, a zirconia compound, a zinc compound, or the like. For additives. When such a water-based adhesive is used, the adhesive layer obtained therefrom is usually much thinner than 1 μm, and the adhesive layer is not actually observed even when the cross section is observed by a usual optical microscopy.

The bonding method of the film using the water-based adhesive is not particularly limited, and the adhesive may be uniformly applied or flowed onto the surface of the film, and the other film may be superposed on the coated surface and dried by a roll or the like. Method and so on. Usually, the adhesive is applied at a temperature of 15 to 40 ° C after the preparation thereof, and the bonding temperature is usually in the range of 15 to 30 ° C.

When a water-based adhesive is used, the film is bonded and dried to remove moisture contained in the aqueous adhesive. The temperature of the drying furnace is preferably 30 ° C to 90 ° C. If it is less than 30 ° C, the surface tends to be easily peeled off. When it is 90 ° C or more, the optical properties of the polarizer or the like are deteriorated due to heat. The drying time can be set to 10 to 1000 seconds.

After drying, it may be further aged at room temperature or a temperature slightly higher than the temperature, for example, at a temperature of about 20 to 45 ° C for about 12 to 600 hours. The temperature at the time of aging is usually set to be lower than the temperature used at the time of drying.

Further, as the nonaqueous binder, a photocurable adhesive can be used. The photocurable adhesive agent may, for example, be a mixture of a photocurable epoxy resin and a photocationic polymerization initiator.

As a method of bonding a film with a photocurable adhesive, a conventionally known method can be used, for example, by a casting method, a wire bar coating method, a gravure coating method, a notch wheel coating method, a doctor blade method. , a die coating method, a dip coating method, a spray method, etc., and an adhesive is applied to the film. Next, a method of laminating two sheets of film is carried out. The casting method is a method in which the two films of the object to be coated are moved to the surface in a substantially vertical direction, a substantially horizontal direction, or an oblique direction therebetween, and the adhesive agent is flown down to the surface thereof to expand.

After the adhesive is applied to the surface of the film, the two films can be bonded by being sandwiched by a nip roll or the like. Moreover, the method of uniformly expanding the laminated body by a roll or the like can be suitably used. At this time, as the material of the roller, metal, rubber, or the like can be used. Further, the method of allowing the laminated body to pass between the rolls and the rolls and expanding by pressurization can be suitably employed. At this time, the roller systems may be the same material or different materials. After bonding by the above-described nip rolls or the like, the thickness of the adhesive layer before drying or curing is preferably 5 μm or less and 0.01 μm or more.

On the subsequent surface of the film, in order to improve the adhesion, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment or the like may be appropriately applied. The saponification treatment may be a method of immersing in an aqueous solution of a base such as sodium hydroxide or potassium hydroxide.

When a photocurable resin is used as the adhesive, the photocurable adhesive is cured by irradiating the active energy ray after the film is laminated. The light source of the active energy ray is not particularly limited, and is preferably an active energy ray having a light-emitting distribution at a wavelength of 400 nm or less. Specifically, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, and a black light can be suitably used. Lamps, microwaves, mercury lamps, halogenated metal lamps, etc.

The light irradiation intensity of the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive, and is not particularly limited. However, the irradiation intensity in the wavelength region effective for activation of the polymerization initiator is 0.1. ~6000mW/cm ^{2 is} preferred. When the irradiation intensity is 0.1 mW/cm ² or more, the reaction time becomes too long, and when it is 6000 mW/cm ² or less, the heat generated by the light source and the heat generated by curing of the photocurable adhesive cause yellow epoxy resin. There is less variation in the variation of the polarizing film and the polarizing film. The light irradiation time of the photocurable adhesive is not particularly limited as long as it is suitably used in accordance with the cured photocurable adhesive, but the integrated light amount expressed by the product of the above-described irradiation intensity and irradiation time is 10 ~ 10000mJ / cm ² of the set preferred embodiment. When the integrated light amount of the photocurable adhesive is 10 mJ/cm ² or more, the active species derived from the polymerization initiator can be sufficiently produced to make the curing reaction more sure; and when the amount is 10000 mJ/cm ² or less, the irradiation time is It will not become too long to maintain good productivity. Further, the thickness of the adhesive layer after the active energy ray irradiation is usually about 0.001 to 5 μm, preferably 0.01 μm or more and 2 μm or less, and more preferably 0.01 μm or more and 1 μm or less.

When the photocurable adhesive containing the film of the polarizer layer and the protective film is cured by irradiation of the active energy ray, the polarizing plate of the polarizing plate layer, the transmittance, the hue, and the transparency of the protective film are used. It is preferred to perform hardening under various conditions without lowering the function.

In the bonding step (S50) of bonding the polarizer layer and the protective film, in order to form a solution containing a solvent in order to form an adhesive layer or an adhesive layer, drying of the multilayer film is performed. The purpose of such drying is mainly to carry out the drying of the adhesive layer or the adhesive layer, and the drying conditions and the like are substantially the same as the drying after the washing step described above. In particular, in order to form an adhesive layer, when a polyvinyl alcohol-based resin aqueous solution or the like is used, it is preferably at a temperature of 60 ° C or higher. Drying is preferred.

[Peeling step (S60)]

After the bonding step (S50), a peeling step of peeling off the base film from the multilayer film to obtain a polarizing plate having a polarizer layer and a protective film is performed (S60). The method of peeling the base film from the multilayer film is not particularly limited, and the same method as the peeling film peeling step which is usually performed on the polarizing plate with the adhesive can be employed. After the bonding step (S50), the peeling may be performed immediately, or the film may be wound into a single roll shape, and a peeling step may be separately provided to peel off.

[other optical layers]

In the polarizing plate obtained by the present invention, a polarizing plate in which other optical layers are laminated can be used in practice. Further, the protective film may have the function of the optical layers.

Examples of the other optical layer include a reflective polarizing film that transmits a certain polarized light and reflects a polarized light having a property opposite thereto; an anti-glare film having a concave-convex shape on the surface; and an anti-reflection function a thin film; a reflective film having a reflective function on the surface; a transflective film having both a reflective function and a transmissive function; and a viewing angle compensation film.

A commercially available product of a reflective polarizing film that reflects a polarized light that transmits a certain polarized light and reflects the opposite property, for example, DBEF (available from 3M Company, Sumitomo 3M (share)), APF (can be obtained from 3M company, Sumitomo 3M (share)). Examples of the viewing angle compensation film include a retardation film made of a polycarbonate resin and a retardation film made of a polycarbonate resin, and a phase difference film made of a cyclic polyolefin resin. membrane. A commercially available product of an optical compensation film which is coated with a liquid crystal compound and is aligned on the surface of the substrate, and is a WV film (manufactured by Fuji FILM Co., Ltd.) and an NH film (JX Nippon Nippon ENERGY Co., Ltd.). ), NV film (JX Nippon Mining ENERGY Co., Ltd.) and so on. In addition, as a commercial product of a retardation film which consists of a cyclic polyolefin resin, the ARTON (registered trademark) film (made by JSR), S-SINA (registered trademark) Industrial (stock) system, ZEONOR (registered trademark) film (made by Japan ZEON Co., Ltd.).

[Second Embodiment]

Fig. 2 is a flow chart showing the manufacture of the polarizing laminate film and the polarizing plate of the second embodiment. The method for producing a polarizing laminated film according to the second embodiment includes a first coating step (S11) in which a polyvinyl alcohol-based resin aqueous solution is applied to one surface of a base film to obtain a coated film; a first drying step (S21) of drying the coated film to obtain a laminated film having a polyvinyl alcohol-based resin layer formed on one surface of the base film, and a second coating step (S12) of the base On the other side of the material film, a polyvinyl alcohol-based resin aqueous solution is applied to obtain a double-coated film, and a second drying step (S22) is performed by drying the double-coated film to obtain polyethylene on both sides of the base film. Two areas of the alcohol resin layer a film; an extending step (S31) of uniaxially stretching the two-layer film to obtain an extended laminated film; and a dyeing step (S40) of dyeing the polyvinyl alcohol-based resin layer into a polarizer layer A polarizing laminated film is obtained; and a polarizing plate is further included in the step of: a bonding step (S50) of bonding the transparent protective film to the polarizing layer of the polarizing laminated film to be opposite to the substrate film A multilayer film is obtained on the side surface; and a peeling step (S60) of peeling off the base film from the multilayer film to obtain a polarizing plate including the polarizer layer and the transparent protective film.

In the present embodiment, by forming a polyvinyl alcohol-based resin layer on both surfaces of the base film, it is possible to simultaneously form a two-layer polarizer layer.

<Production steps>

Hereinafter, each step of the second embodiment of Fig. 2 will be described in comparison with the steps corresponding to the first embodiment of Fig. 1. Further, the points which are not particularly described are performed in the same manner as the steps corresponding to the first embodiment. The same steps are denoted by the same reference numerals and the description will be omitted.

[First Coating Step (S11)]

The first coating step (S11) is the same step as the coating step (S10) in Fig. 1 .

[First drying step (S21)]

In the first drying step (S21), the moisture content of the laminated film after drying is 0.3% by mass or more and 3% by mass or less, and preferably 0.35% by mass or more and 1.8% by mass or less. By setting such a water content rate, it is easy to adjust the water content at the start of uniaxial stretching to a desired value in the extending step (S31) to be described later. The numerical range in which the average moisture content of the coating film in the first drying step (S21) is preferably changed, the preferred drying conditions, and the like are as described in the drying step (S20) of the first embodiment.

[Second coating step (S12)]

The second coating step (S12) is applied to the surface of the base film, and is coated on the surface opposite to the surface on which the polyvinyl alcohol aqueous solution is applied in the first coating step (S11). A resin aqueous solution is obtained to obtain a step of coating the film on both sides. The coating conditions of the polyvinyl alcohol-based resin aqueous solution in the second coating step (S12) are as described in the coating step (S10) of the first embodiment.

[Second drying step (S22)]

The second drying step (S22) is the same step as the drying step (S20) of the first embodiment. The numerical range in which the average moisture content of the coating film in the second drying step (S22) is preferably changed, the preferred drying conditions, and the like are also as described in the drying step (S20) of the first embodiment.

[Extension step (S31)]

Here, the two-layer film obtained in the second drying step (S22) is used. Extend. In the extending step (S31), the uniaxial stretching is started in a state where the water content of the two-area film is 0.5% by mass or more. When the moisture content is 0.5% by mass or more at the start of uniaxial stretching, a polarizing laminate film or a polarizing plate having a polarizing plate layer having excellent optical properties can be produced. Moreover, the adjustment of the water content can be performed, for example, by adjusting the degree of drying in the first drying step (S21) and the second drying step (S22), or by adjusting in a humidity control step to be described later.

The degree of drying in the first drying step (S21) and the second drying step (S22) is in addition to the temperature and time of each step described above, and also in accordance with the polyvinyl alcohol-based resin coating layer formed on the base film. Since the thickness (or the weight per unit area) varies depending on the water concentration in the environment of the drying step, the water vapor pressure, the humidity, and the like, a simple preliminary experiment is performed, and after the second drying step (S22), the predetermined moisture content is obtained ( The condition may be adjusted so as to be 0.5% by mass or more and 4% by mass or less, preferably 0.6% by mass or more and 2.5% by mass or less. It is also possible to introduce the air adjusted to the predetermined water vapor pressure into the drying furnace as the case may be. In the second drying step (S22), the laminated film is dried to a predetermined moisture content, and it is preferable to directly deliver the stretching step (S31) while maintaining the moisture content, and it is also possible to adjust the humidity conditioning step to be described later. After the moisture rate, it is delivered to the stretching step (S31).

(conditioning step)

After the second drying step (S22), a humidity control step may be further provided in which the moisture content of the two-layer film is 0.5% by mass or more and 4 The mass% or less is preferably adjusted to be 0.6% by mass or more and 2.5% by mass or less. In this case, the two-layer film obtained by the humidity-conditioning step is directly supplied to the state in which the water content is 0.5% by mass or more and 4% by mass or less, preferably 0.6% by mass or more and 2.5% by mass or less. The step of extending (S31). The humidity control in the humidity control step is applied in the same manner as described in the humidity control step of the first embodiment.

[Examples]

[Example 1]

As shown in the flow chart shown in FIG. 2, the polarizing plate is produced by performing the dyeing step (S40) to produce a double-sided polarizing laminate film, and further performing the peeling step (S60).

(substrate film)

A random copolymer of propylene/ethylene containing about 5% by weight of ethylene units (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumitomo NOBLEN W151, melting point) was produced by co-extrusion using a multi-layer extrusion molding machine. Tm = 138 ° C) The both sides of the resin layer are composed of a homopolymer polypropylene of propylene (Sumitomo Chemical Co., Ltd., trade name: Sumitomo NOBLEN FLX80E4, melting point Tm = 163 ° C). A substrate film of a three-layer structure of a resin layer. The total thickness of the obtained base film was 100 μm, and the thickness ratio of each layer (FLX80E4/W151/FLX80E4) was 3/4/3.

(primer solution)

Polyvinyl alcohol powder (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Z-200, average polymerization degree 1100, average saponification degree: 99.5 mol%) was dissolved in hot water at 95 ° C to prepare an aqueous solution having a concentration of 3 wt%. . Into the obtained aqueous solution, 1 part by weight of a crosslinking agent (manufactured by Tajika Chemical Industry Co., Ltd., trade name: Sumirez Resin 650) was mixed with 2 parts by weight of the polyvinyl alcohol powder to obtain a primer solution.

(aqueous solution of polyvinyl alcohol resin)

Polyvinyl alcohol powder (manufactured by KURARAY, trade name: PVA124, average polymerization degree 2400, average saponification degree: 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 8 wt%. .

(first coating step, first drying step)

The substrate film was continuously conveyed while being subjected to corona treatment, and then the primer solution was continuously applied to the corona-treated surface using a small-diameter gravure coater, thereby making it 60. It was dried at ° C for 3 minutes to form a primer layer having a thickness of 0.2 μm. Next, the polyvinyl alcohol aqueous solution was continuously applied to the primer layer by a notch coater while carrying the film (first coating step), and dried at 90 ° C for 4 minutes (first drying) In the step), a polyvinyl alcohol-based resin layer (hereinafter referred to as a "first PVA layer") having a thickness of 11.5 μm was formed on the primer layer to obtain a single-area layer film.

(Measurement of moisture content)

The moisture content of the single-area film produced as described above was measured. 0.39 mass%. From the moisture content and the moisture content of the coating film before entering the first drying step, the drying rate in the first drying step was calculated to be 16.4% by mass/minute in terms of the change in the average moisture content. Further, when the moisture content of the first PVA layer monomer of the single-area layer film was measured, it was 2.76 mass%.

(second coating step, second drying step)

The single-layer film produced as described above was formed on the surface of the base film opposite to the surface on which the first PVA layer was formed, and was formed in the same manner as described above to form a primer layer of 0.2 μm. The lacquer layer was coated with a polyvinyl alcohol aqueous solution (second coating step), and dried at 90 ° C for 4 minutes (second drying step) to form a polyvinyl alcohol having a thickness of 10.6 μm on the primer layer. A resin layer (hereinafter, "second PVA layer") was obtained to obtain a two-layer film.

(Measurement of moisture content)

When the moisture content of the two-area film produced as described above was measured, it was 0.6% by mass. From the moisture content and the moisture content of the double-coated film before entering the second drying step, the drying rate in the second drying step was 15.9% by mass/min based on the change in the average moisture content. Further, when the water content of the first PVA layer monomer and the water content of the second PVA layer monomer in the two-layer film were measured, they were 4.66 mass% and 3.79 mass%, respectively.

(extension step)

The two-layer film obtained as described above is continuously conveyed while being stretched at a stretching temperature of 160 ° C by a stretching method between the nip rolls. (Thin film conveyance direction) The elongation laminated film was obtained by extending 5.8 times. In the extended laminated film, the thickness of the first PVA layer was 5.7 μm, and the thickness of the second PVA layer was 5.4 μm.

(staining step)

While continuously transporting the extended laminated film obtained as described above, the dyed solution containing 30% of iodine and potassium iodide was immersed in the dyeing solution containing iodine and potassium iodide to dye the first PVA layer and the second PVA layer, and then 10 Rinse the excess staining solution with pure water at °C. Next, a crosslinking solution containing 76% of boric acid and potassium iodide was immersed in a residence time of about 600 seconds to carry out a crosslinking treatment. Subsequently, it was washed with pure water of 10 ° C for 4 seconds and dried at 80 ° C for 300 seconds to obtain a polarizing laminated film.

Moreover, the mixing ratio of the dyeing solution and the crosslinking solution is set to

<dyeing solution>

Water: 100 parts by weight

Iodine: 0.6 parts by weight

Potassium iodide: 10 parts by weight

<cross-linking solution>

Water: 100 parts by weight

Boric acid: 9.5 parts by weight

Potassium iodide: 5 parts by weight.

(Measurement of optical properties)

In the first PVA layer (first polarizer layer) and the second PVA layer (second polarizer layer) of the obtained polarizing laminated film, the polarizer layer which is not the measurement target is peeled off and prepared, and the polarizer to be measured is prepared. In the laminate of the layer and the base film, an acrylic pressure-sensitive adhesive is laminated on the polarizer layer of the laminate, and the acrylic adhesive layer is bonded to the glass to form an evaluation sample.

The optical characteristics of the evaluation sample were measured by a spectrophotometer (manufactured by JASCO Corporation, V7100) equipped with an integrating sphere. The incident light system is entered from the glass side, and the MD transmittance and the TD transmittance are obtained in the wavelength range of 380 nm to 780 nm, and the single transmittance and the polarization degree at each wavelength are calculated according to the formulas (3) and (4). The illuminance correction was performed in accordance with the 2D field of view (C light source) of JIS Z 8701, and the illuminance corrected single transmittance (Ty) and the opacity corrected polarization (Py) were obtained.

In the above, the "MD transmittance" is a transmittance when the direction of the polarized light emitted from the Glan-Thomson ridge is parallel to the transmission axis of the evaluation sample, and in the formulas (3) and (4), It is represented by "MD". In addition, the "TD transmittance" is a transmittance when the direction of the polarized light emitted from the Glan-Thomson(R) is orthogonal to the transmission axis of the evaluation sample, and is expressed in the equations (3) and (4). "TD" means.

Monomer transmittance (%) = (MD + TD) / 2 (3)

The degree of polarization (%) = {(MD-TD) / (MD + TD)} ^1/2 × 100 Equation (4).

(adhesive solution)

Polyvinyl alcohol powder (manufactured by KURARAY, trade name: KL-318, average polymerization degree: 1800) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3 wt%. In the obtained aqueous solution, 1 part by weight of a crosslinking agent (manufactured by Tajika Chemical Industry Co., Ltd., trade name: Sumirez Resin 650) was mixed with 2 parts by weight of the polyvinyl alcohol powder to obtain an adhesive solution.

(Fitting step)

After the above-mentioned adhesive solution was applied to the polarizing plate layers on both sides, the saponified protective film having a thickness of 40 μm (Konica Minolta Co., Ltd., product) was continuously conveyed while continuously transporting the polarizing laminated film obtained above. Name: KC4UY, a transparent protective film made of cellulose triacetate (TAC) is bonded to the coated surface, and is pressed by a pair of bonding rolls to obtain KC4UY/1st Multilayer film composed of polarizer layer/primer layer/substrate film/primer layer/second polarizer layer/KC4UY (bonding step). The multilayer film is peeled off between the base film and the primer layer, and is set as two laminates of KC4UY/first polarizer layer/primer layer/substrate film, primer layer/second polarizer layer/KC4UY Further, the base film is peeled off (peeling step). A cyclic polyolefin-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name: ZF-14) having a thickness of 23 μm was bonded to the primer layer of each laminated body through an adhesive layer to obtain a KC4UY/polarized sheet layer. / Primer layer / adhesive layer / ZF-14 two polarizing plates. In the peeling step, no breakage occurred.

[Embodiment 2]

In addition to changing the drying conditions in the first drying step and the second drying step to 90 ° C for 3 minutes, the thickness of the first PVA layer after the first drying step was 9.2 μm, and the second PVA layer after the second drying step was performed. A polarizing laminated film and a polarizing plate were produced in the same manner as in Example 1 except that the thickness was 9.4 μm. In the peeling step, no breakage occurred.

[Example 3]

In addition to the drying conditions in the first drying step and the second drying step, either of them was changed to 90 ° C for 2 minutes, followed by 80 ° C for 1.5 minutes for a total of 3.5 minutes, and the first PVA after the first drying step was further changed. The polarizing laminated film and the polarizing plate were produced in the same manner as in Example 1 except that the thickness of the layer was 9.3 μm, and the thickness of the second PVA layer after the second drying step was 9.2 μm. In the peeling step, no breakage occurred.

[Example 4]

In addition to the drying conditions in the first drying step and the second drying step, either one was changed to 75 ° C for 2 minutes, followed by 80 ° C for 2 minutes for a total of 4 minutes, and the first PVA after the first drying step was further changed. The polarizing laminated film and the polarizing plate were produced in the same manner as in Example 1 except that the thickness of the layer was 9.0 μm, and the thickness of the second PVA layer after the second drying step was 9.1 μm. In the peeling step, no breakage occurred.

[Example 5]

Performed as shown in Figure 1 by performing to the staining step (S40) A single-sided polarizing laminated film is produced, and further, a polarizing plate is produced by performing the peeling step (S60). The base film, the primer solution, and the polyvinyl alcohol aqueous solution were used in the same manner as in Examples 1 to 4.

(first coating step, first drying step)

The substrate film was continuously conveyed while being subjected to corona treatment, and then the primer solution was continuously applied to the corona-treated surface using a small-diameter gravure coater, thereby making it 60. It was dried at ° C for 3 minutes to form a primer layer having a thickness of 0.2 μm. Next, the polyvinyl alcohol aqueous solution was continuously applied onto the primer layer by a notch coater while conveying the film (first coating step), and was then allowed to stand at 90 ° C for 2 minutes, followed by 80 ° C. After 1.5 minutes of total drying for 3.5 minutes (first drying step), a first PVA layer having a thickness of 9.2 μm was formed on the primer layer to obtain a single-area layer film.

(extension step)

While continuously transporting the single-layer film obtained as described above, the film was stretched by 5.8 times in the machine direction (film conveyance direction) at an extension temperature of 160 ° C by a stretching method between the nip rolls to obtain a one-side stretched film. . In the extended laminated film, the thickness of the first PVA layer was 4.7 μm.

(staining step)

The one-side extended laminated film obtained as described above was dyed in the same manner as in Example 1 to obtain a single-sided polarizing laminated film.

(Fitting step)

While continuously applying the obtained single-sided polarizing laminate film, the same adhesive solution as in Example 1 was applied onto a polarizer (first polarizer layer), and then a saponified protective film having a thickness of 40 μm ( Konica Minolta Co., Ltd., trade name: KC4UY, a transparent protective film made of cellulose triacetate (TAC), is attached to the coated surface, and is pressed by passing between a pair of bonding rolls. Adhesively, a multilayer film composed of KC4UY/first polarizing sheet/primer layer/substrate film was obtained (bonding step).

From the multilayer film, the base film is peeled off between the base film and the primer layer to form a laminate composed of KC4UY/first polarizer layer/primer layer (peeling step). A cyclic polyolefin-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name: ZF-14) having a thickness of 23 μm was bonded to the primer layer of the obtained laminate through the adhesive layer to obtain KC4UY/ 1 polarizing plate / primer layer / adhesive layer / ZF-14 formed by a polarizing plate. In the peeling step, no breakage occurred.

[Embodiment 6]

The drying conditions in the first drying step were carried out in the same manner as in Example 4, and the thickness of the PVA layer after the first drying step was changed to 9.0 μm, and a single-sided polarizing layer was formed in the same manner as in Example 5. Film and polarizing plate. In the peeling step, no breakage occurred.

[Comparative Example 1]

In addition to changing the thickness of the first PVA layer after the first drying step The polarizing laminated film and the polarizing plate were produced in the same manner as in Example 1 except that the thickness of the second PVA layer after the second drying step was changed to 8.9 μm.

[Comparative Example 2]

The polarizing layer was formed in the same manner as in Example 1 except that the thickness of the first PVA layer after the first drying step was changed to 9.2 μm, and the thickness of the second PVA layer after the second drying step was changed to 9.3 μm. Film and polarizing plate.

Table 1 shows the drying conditions and the results of the respective measurement results in Examples 1 to 6 and Comparative Examples 1 and 2.

As shown in Table 1, in Comparative Examples 1 and 2, the moisture content of the laminated film provided in the state of the stretching step was less than 0.5% by mass, and the moisture content after the first drying step was less than 0.3% by mass. The illuminance-corrected polarization Py of the polarizing laminated films of Comparative Examples 1 and 2 was lower than the polarizing laminated films of Examples 1 to 6.

An acrylic adhesive layer was disposed on the KC4UY surface of the polarizing plate composed of KC4UY/polarizing sheet/primer layer/adhesive layer/ZF-14 prepared in Examples 1 to 6, and the adhesive layer was passed through the adhesive layer. The glass bonded to the glass was used as an evaluation sample, and the heat and humidity resistance test and the heat resistance test shown below were carried out. As a result, the evaluation sample of either of them was about 0.001% in the heat and humidity resistance test, and the ΔPy in the heat resistance test was about 0.005%, which was a level of no problem. As a result of the similar evaluation of the polarizing plates produced in Comparative Examples 1 and 2, ΔPy was larger than the evaluation samples of Examples 1 to 6.

(1) Evaluation of heat and humidity resistance

The illuminance corrected polarization Py after the heat and humidity resistance test which was allowed to stand for 500 hours in an environment of a temperature of 65 ° C and a relative humidity of 90% was measured by an absorptiometer (manufactured by JASCO Corporation, V7100), and Py before the test. The difference ΔPy between the two (Py after the test and Py after the test) was obtained. In the measurement of Py, the evaluation sample was attached so that the incident light was irradiated onto the glass surface, and the luminosity correction polarization Py after the test was performed at the temperature of 23 ° C and the relative humidity of 55 after the above-mentioned heat and humidity resistance test. The measurement was carried out after standing for about 12 hours in an environment of %. The smaller the absolute value of ΔPy, the higher the moist heat resistance.

(2) Evaluation of heat resistance

The heat resistance test was carried out by allowing to stand for 500 hours in a dry environment at a temperature of 85 ° C, and the visual sensitivity correction polarization Py before and after the test was obtained in the same manner as the method described in the above-mentioned heat and humidity resistance test. The difference ΔPy (Py after the test, Py after the test). The smaller the absolute value of ΔPy, the higher the heat resistance.

S10‧‧‧ Coating step

S20‧‧‧ drying step

S30‧‧‧Extension step

S40‧‧‧Staining step

S50‧‧‧Finishing steps

S60‧‧‧ peeling step

Claims (8)

A method for producing a polarizing laminated film, comprising: a coating step of applying a solution of a polyvinyl alcohol-based resin to a base film to obtain a coated film; and a drying step of drying the coated film a laminated film in which a polyvinyl alcohol-based resin layer is formed on a base film; an extending step of uniaxially stretching the laminated film to obtain an extended laminated film; and a dyeing step of the polyvinyl alcohol-based resin layer The polarizing layer is obtained by dyeing to obtain a polarizing layer, and the uniaxial stretching is started in a state in which the water content of the laminated film is 0.3% by mass or more. The method for producing a polarizing laminate film according to the first aspect of the invention, wherein the drying step is performed so that the average moisture content change of the coating film is 5 to 65% by mass/minute. The method for producing a polarizing laminate film according to the first or second aspect of the invention, wherein after the drying step, the humidity conditioning step of adjusting the moisture content of the laminated film to 0.3% by mass or more And the laminated film after the humidity adjustment step is provided to the extending step while maintaining the moisture content. A method for producing a polarizing laminated film, comprising: a first coating step of applying a solution of a polyvinyl alcohol-based resin to one surface of a base film to obtain a coated film; and a first drying step; Drying the coated film to obtain a laminated film of a polyvinyl alcohol-based resin layer is formed on one surface of the base film, and a second coating step is applied to the other surface of the base film by applying an aqueous solution of a polyvinyl alcohol-based resin to obtain a double-coated film; a second drying step of drying the double-coated film to obtain a two-layer film having a polyvinyl alcohol-based resin layer formed on both surfaces of the base film; and an extending step of uniaxially stretching the two-area film An extended laminated film is obtained; and a dyeing step of dyeing the polyvinyl alcohol-based resin layer into a polarizing layer to obtain a polarizing laminated film; and the extending step is a moisture content of 0.5% by mass or more of the two-area film. The aforementioned uniaxial extension is started in the state. The method for producing a polarizing laminated film according to the fourth aspect of the invention, wherein the first drying step is performed such that the moisture content of the laminated film after drying is 0.3% by mass or more. The method for producing a polarizing laminate film according to the fourth or fifth aspect, wherein the first drying step and the second drying step are an average moisture content change of the coating film and the double-coated film. The average moisture content change is performed in a manner of 5 to 65% by mass/minute. The method for producing a polarizing laminate film according to any one of the fourth to sixth aspect of the invention, wherein after the second drying step, the moisture content of the two-area layer film is 0.5% by mass or more. The humidity conditioning step is adjusted, and will be adjusted before the humidity conditioning step The two-layer film is provided to the aforementioned stretching step while maintaining the moisture content. A method of producing a polarizing plate, comprising the steps of: producing a polarizing laminated film according to the method for producing a polarizing laminated film according to any one of claims 1 to 7; a step of bonding a protective film to the surface of the polarizer layer on the opposite side of the base film to obtain a multilayer film; and peeling the base film from the multilayer film to obtain the polarizer layer And a peeling step of the polarizing plate of the protective film.