Method for manufacturing polarizing film, and method for manufacturing polarizing film

Abstract

Provided is a method for producing a polarizing film, the method including: a process (I-1) for producing a polarizing film containing water by transporting a polyvinyl alcohol-based film in a length direction while applying at least a dyeing process, a cross-linking process, and a stretching process to the polyvinyl alcohol-based film; a process (I-2) for producing a polarizing film containing components impregnated in a liquid by applying a coating liquid to the obtained polarizing film containing water in a state where the water content of the polarizing film is 20% by mass or more; and a process (I-3) for producing a dried polarizing film by applying a drying process to the obtained polarizing film containing components impregnated in a liquid. The method for producing a polarizing film according to the present application can allow a polarizing film to contain any components simply and sufficiently.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing a polarizing film, and a method for manufacturing a polarizing film. BACKGROUND

[0002] In the past, as a polarizing film (polarizer) for various image display devices such as liquid crystal display devices, organic EL display devices, and the like, a polyvinyl alcohol-based film subjected to dyeing treatment (containing iodine, a dichroic dye, or the like) has been used from the viewpoint of simultaneously having high transmittance and high polarization. The polarizing film is manufactured by, after subjecting a polyvinyl alcohol-based film to each treatment such as dyeing, crosslinking, stretching, and the like in a bath (treatment bath), drying it. In addition, the above-described polarizing film is generally used in the form of a polarizing film (polarizing plate) in which a protective film such as cellulose triacetate is attached to one face or both faces thereof with an adhesive.

[0003] As a method for manufacturing a polarizing film, for example, in Patent Literatures 1 to 2, a method for manufacturing a polarizing film containing components such as a metal salt containing zinc, copper, aluminum, or the like by adding the components in a treatment bath, thereby making the polarizing film contain the components, is disclosed to improve the durability of the polarizing film. In addition, in Patent Literatures 3 to 4, a method for manufacturing a polarizing film in which an organic titanium compound or the like is added in a treatment bath is disclosed.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: International Publication No. 2016 / 117659

[0007] Patent Literature 2: Japanese Patent Application Laid-Open No. 2006-047978

[0008] Patent Literature 3: Japanese Patent Application Laid-Open No. 2008-46257

[0009] Patent Literature 4: Japanese Patent Application Laid-Open No. H6-172554 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] However, in the method for manufacturing a polarizing film, when the above-described components are added in a treatment bath, there are problems in that the amount thereof becomes large, and waste liquid treatment of the treatment liquid needs to be performed.

[0012] In view of the above, an object of the present application is to provide a method for manufacturing a polarizing film capable of simply and sufficiently containing an arbitrary component.

[0013] In addition, an object of the present application is to provide a method for manufacturing a polarizing film using a polarizing film obtained by the above-described method for manufacturing a polarizing film.

[0014] Method for solving the problem

[0015] That is, the present application relates to a method for manufacturing a polarizing film, the method comprising: a process (I-1) for manufacturing a polarizing film containing water, by transporting a polyvinyl alcohol-based film in a length direction while applying at least a dyeing process, a crosslinking process, and a stretching process to the polyvinyl alcohol-based film; a process (I-2) for manufacturing a polarizing film containing components immersed in a liquid, by applying a liquid to the obtained polarizing film containing water, in a state where the water content ratio of the polarizing film is 20% by weight or more; and a process (I-3) for manufacturing a dried polarizing film, by applying a drying process to the obtained polarizing film containing components immersed in a liquid.

[0016] In addition, the present application relates to a method for manufacturing a polarizing film, the method comprising: a process (II-0) for preparing a laminate by forming a polyvinyl alcohol-based resin layer containing a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate; a process (II-1) for manufacturing a laminate having a polarizing film containing water, by transporting the obtained laminate in a length direction while applying at least a gas atmosphere auxiliary stretching treatment process, a dyeing treatment process, and a water solution stretching treatment process to the laminate; a process (II-2) for manufacturing a laminate having a polarizing film containing components immersed in a liquid, by applying a liquid to the obtained laminate having a polarizing film containing water, in a state where the water content ratio of the polarizing film is 20% by weight or more; and a process (II-3) for manufacturing a dried polarizing film, by applying a drying treatment process to the obtained laminate having a polarizing film containing components immersed in a liquid.

[0017] In addition, the present application relates to a method for manufacturing a polarizing film, the method comprising: a process for laminating a transparent protective film to at least one side of a polarizing film obtained by the above-mentioned method for manufacturing a polarizing film, via an adhesive layer.

[0018] Effects of the invention

[0019] The detailed circumstances of the mechanism of action of the effects in the method for manufacturing a polarizing film of the present application are not clear, but are presumed as follows. However, the present application can be explained without being limited to this mechanism of action.

[0020] The manufacturing method of the polarizing film of the present application includes: a process (I-1) of manufacturing a polarizing film containing water by transporting a polyvinyl alcohol-based film in a length direction while applying at least a dyeing process, a cross-linking process and a stretching process to the polyvinyl alcohol-based film; a process (I-2) of manufacturing a polarizing film containing components of a liquid impregnated therein by applying a liquid to the obtained polarizing film containing water in a state where the moisture content of the polarizing film is 20% by weight or more; and a process (I-3) of manufacturing a dried polarizing film by applying a drying process to the obtained polarizing film containing components of the liquid impregnated therein. Alternatively, the manufacturing method of the polarizing film of the present application includes: a process (II-0) of preparing a laminate by forming a polyvinyl alcohol-based resin layer containing a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate; a process (II-1) of manufacturing a laminate having a polarizing film containing water by transporting the obtained laminate in a length direction while applying at least a gas atmosphere auxiliary stretching process, a dyeing process and a water solution stretching process to the laminate; a process (II-2) of manufacturing a laminate having a polarizing film containing components of a liquid impregnated therein by applying a liquid to the obtained laminate having a polarizing film containing water in a state where the moisture content of the polarizing film is 20% by weight or more; and a process (II-3) of manufacturing a dried polarizing film by applying a drying process to the obtained laminate having a polarizing film containing components of the liquid impregnated therein. In the conventional manufacturing method of the polarizing film, after at least a dyeing process, a cross-linking process and a stretching process are applied to a polyvinyl alcohol-based film, a drying process is then applied. Alternatively, in the conventional manufacturing method of the polarizing film, after a process of preparing a laminate by forming a polyvinyl alcohol-based resin layer containing a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate, and at least a gas atmosphere auxiliary stretching process, a dyeing process and a water solution stretching process are applied to the obtained laminate, a drying process is then applied. On the other hand, in the manufacturing method of the polarizing film of the present application, a polarizing film containing water, or a laminate having a polarizing film containing water is manufactured as described above. With respect to the polarizing film in the polarizing film containing water, or the laminate having a polarizing film containing water, a process of applying a liquid is applied in a state where the moisture content of the polarizing film is 20% by weight or more, and therefore, the polarizing film containing water can be simply and sufficiently impregnated with any components contained in the liquid. DETAILED DESCRIPTION

[0021] <Manufacturing method of polarizing film>

[0022] The manufacturing method of the polarizing film of the present application includes: a process (I-1) of manufacturing a water-containing polarizing film by carrying a polyvinyl alcohol-based film in a length direction while applying at least a dyeing process, a cross-linking process, and a stretching process to the polyvinyl alcohol-based film; a process (I-2) of manufacturing a polarizing film containing components in a liquid by applying a coating liquid to the obtained water-containing polarizing film in a state where a moisture content of the polarizing film is 20% by mass or more; and a process (I-3) of manufacturing a dried polarizing film by applying a drying process to the obtained polarizing film containing the components in the liquid.

[0023] <Process (I-1) of manufacturing a water-containing polarizing film>

[0024] The manufacturing method of the polarizing film of the present application includes: a process (I-1) of manufacturing a water-containing polarizing film by carrying a polyvinyl alcohol-based film in a length direction while applying at least a dyeing process, a cross-linking process, and a stretching process to the polyvinyl alcohol-based film.

[0025] The polyvinyl alcohol (PVA)-based film can be used without particular limitation and is a polyvinyl alcohol (PVA)-based film having light transmittance in a visible light region and obtained by dispersing and adsorbing a dichroic substance such as iodine or a dichroic dye. The thickness of the PVA-based film, which is usually used in the form of a film roll, is preferably about 1 to 100 μm, more preferably about 1 to 50 μm, and the width is preferably about 100 to 5000 mm.

[0026] As the material of the polyvinyl alcohol-based film, polyvinyl alcohol or a derivative thereof can be exemplified. As the derivative of the polyvinyl alcohol, for example, polyvinyl formal, polyvinyl acetal, an olefin such as ethylene or propylene, a derivative obtained by modifying with an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, or crotonic acid, an alkyl ester thereof, acrylamide, or the like can be exemplified. The average polymerization degree of the polyvinyl alcohol is preferably about 100 to 10000, more preferably about 1000 to 10000, and further preferably about 1500 to 4500. In addition, the saponification degree of the polyvinyl alcohol is preferably about 80 to 100 mol%, and more preferably about 95 mol% to 99.95 mol%. Note that the average polymerization degree and the saponification degree can be found based on JIS K 6726.

[0027] An additive such as a plasticizer, a surfactant, or the like can be contained in the polyvinyl alcohol-based film. As the plasticizer, for example, a polyhydric alcohol such as glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, or polyethylene glycol, a condensate thereof, or the like can be exemplified. The amount of the additive is not particularly limited, and for example, about 20% by mass or less in the polyvinyl alcohol-based film is appropriate.

[0028] <Dyeing process>

[0029] The dyeing process is a treatment process in which the polyvinyl alcohol film is immersed in a dyeing bath, and can orient dichroic substances such as iodine or dichromatic dyes on the polyvinyl alcohol film. The dyeing solution is preferably an aqueous iodine solution, and more preferably contains iodine and an iodide as a dissolution aid. Note that examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like. Of these, potassium iodide is preferred.

[0030] The concentration of iodine in the dyeing bath is preferably about 0.01 to 1% by weight, and more preferably about 0.02 to 0.5% by weight. The concentration of the iodide in the dyeing bath is preferably about 0.01 to 10% by weight, and more preferably about 0.05 to 5% by weight.

[0031] The temperature of the dyeing bath is preferably about 10 to 50°C, and more preferably about 15 to 45°C. The immersion time in the dyeing bath cannot be determined generally, and is preferably about 10 to 300 seconds, and more preferably about 20 to 240 seconds, because the degree of dyeing of the polyvinyl alcohol film is affected by the temperature of the dyeing bath. The dyeing process can be performed only once, or can be performed multiple times as necessary.

[0032] <Interlinking Process>

[0033] The interlinking process is a treatment process in which the polyvinyl alcohol film that has been dyed by the dyeing process is immersed in a treatment bath (interlinking bath) containing a boron compound, and can interlink the polyvinyl alcohol film by the boron compound, and adsorb iodine molecules or dye molecules to the interlinked structure. Examples of the boron compound include boric acid, borate, borax, and the like. The interlinking bath is generally an aqueous solution, and can be a mixed solution of an organic solvent that is miscible with water and water, for example. The interlinking bath can contain an iodide such as potassium iodide.

[0034] The concentration of the boron compound in the interlinking bath is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and further preferably about 2 to 5% by weight. When an iodide such as potassium iodide is used in the interlinking bath, the concentration of the iodide such as potassium iodide in the interlinking bath is preferably about 1 to 15% by weight, and more preferably about 1.5 to 10% by weight.

[0035] The temperature of the cross-linking bath is preferably about 20 to 70°C, more preferably about 30 to 60°C. The immersion time in the cross-linking bath cannot be determined generally because the degree of cross-linking of the polyvinyl alcohol-based film is affected by the temperature of the cross-linking bath, and is preferably about 5 to 300 seconds, more preferably about 10 to 200 seconds. The cross-linking process can be performed only once, or as many times as necessary.

[0036] <Stretching Process>

[0037] The stretching process is a process in which the polyvinyl alcohol-based film is stretched in at least one direction at a given stretch ratio. In general, the polyvinyl alcohol-based film is uniaxially stretched in the conveyance direction (lengthwise direction). The method of stretching is not particularly limited, and any of a wet stretching method and a dry stretching method can be used. The stretching process can be performed only once, or as many times as necessary. The stretching process can be performed at any stage in the manufacture of the polarizing film.

[0038] The treatment bath (stretching bath) in the wet stretching method can generally use water, or a mixed solution of an organic solvent miscible with water and water, or the like. The stretching bath can contain an iodide such as potassium iodide. In the case where an iodide such as potassium iodide is used in the stretching bath, the concentration of the iodide in the stretching bath is preferably about 1 to 15% by weight, more preferably about 2 to 10% by weight. In addition, in order to increase the degree of cross-linking, the above-described boron compound can be contained in the treatment bath (stretching bath), and in this case, the concentration of the boron compound in the stretching bath is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight.

[0039] The temperature of the stretching bath is preferably about 25 to 80°C, more preferably about 40 to 75°C. The immersion time in the stretching bath cannot be determined generally because the degree of stretching of the polyvinyl alcohol-based film is affected by the temperature of the stretching bath, and is preferably about 10 to 800 seconds, more preferably about 30 to 500 seconds. Note that the stretching process in the wet stretching method can be performed together with any one or more of the dyeing process, the cross-linking process, the swelling process described later, and the cleaning process described later.

[0040] As the dry stretching method, for example, an inter-roller stretching method, a heated roller stretching method, a compression stretching method, or the like can be given. Note that the dry stretching method can be performed together with the drying process described later.

[0041] The total draw ratio (cumulative draw ratio) applied to the above polyvinyl alcohol-based film can be appropriately set according to the purpose, and is preferably about 2 to 7 times, more preferably about 3 to 6.8 times, and further preferably about 3.5 to 6.5 times.

[0042] In the process of manufacturing the above polarizing film containing water, in addition to the above dyeing process, crosslinking process, and stretching process applied to the above polyvinyl alcohol-based film, a swelling process can also be applied, and a cleaning process can also be applied.

[0043] <Swelling Process>

[0044] The above swelling process is a treatment process in which the polyvinyl alcohol-based film is immersed in a swelling bath, and can remove dirt, anti-blocking agents, and the like from the surface of the polyvinyl alcohol-based film, and can also inhibit dyeing unevenness by swelling the polyvinyl alcohol-based film. The above swelling bath generally uses water, distilled water, pure water, or the like as a main component. A surfactant, alcohol, or the like can be appropriately added to the above swelling bath according to a general method.

[0045] The temperature of the above swelling bath is preferably about 10 to 60°C, and more preferably about 15 to 45°C. In addition, the immersion time in the above swelling bath cannot be determined generally because the degree of swelling of the polyvinyl alcohol-based film is affected by the temperature of the swelling bath, and is preferably about 5 to 300 seconds, and more preferably about 10 to 200 seconds. The above swelling process can be applied only once, or can be applied multiple times as necessary.

[0046] <Cleaning Process>

[0047] The above cleaning process is a treatment process in which the polyvinyl alcohol-based film is immersed in a cleaning bath, and can remove foreign matter remaining on the surface of the polyvinyl alcohol-based film or the like. The above cleaning bath generally uses water, distilled water, pure water, or the like as a main component. In addition, a potassium iodide or the like can be contained in the above cleaning bath, and in this case, the concentration of the potassium iodide or the like in the above cleaning bath is preferably about 1 to 10% by weight, more preferably about 2 to 4% by weight, and further preferably about 1.6 to 3.8% by weight.

[0048] The temperature of the above cleaning bath is preferably about 5 to 50°C, more preferably about 10 to 40°C, and further preferably about 15 to 30°C. In addition, the immersion time in the above cleaning bath cannot be determined generally because the degree of cleaning of the polyvinyl alcohol-based film is affected by the temperature of the cleaning bath, and is preferably about 1 to 100 seconds, more preferably about 2 to 50 seconds, and further preferably about 3 to 20 seconds. The above swelling process can be applied only once, or can be applied multiple times as necessary.

[0049] Further, additives such as a zinc salt, a pH adjuster, a pH buffer, and other salts can be contained in each of the treatment baths in the swelling process, the dyeing process, the cross-linking process, the stretching process, and the cleaning process. As the zinc salt, for example, zinc chloride, zinc iodide, and other halogenated zincs; zinc sulfate, zinc acetate, and other inorganic zinc salts can be exemplified. As the pH adjuster, for example, strong acids such as hydrochloric acid, sulfuric acid, and nitric acid; and strong bases such as sodium hydroxide and potassium hydroxide can be exemplified. As the pH buffer, for example, carboxylic acids such as acetic acid, oxalic acid, and citric acid and salts thereof; inorganic weak acids such as phosphoric acid and carbonic acid and salts thereof can be exemplified. As the other salts, for example, chlorides such as sodium chloride, potassium chloride, and barium chloride; nitrates such as sodium nitrate and potassium nitrate; sulfates such as sodium sulfate and potassium sulfate; and salts of alkali metals and alkaline earth metals can be exemplified.

[0050] <Manufacturing process of a polarizing film containing components impregnated in a liquid (I-2)>

[0051] The manufacturing method of the polarizing film of the present application includes a process of applying a liquid to the obtained polarizing film containing water in a state where the water content of the polarizing film is 20% by weight or more, thereby manufacturing a polarizing film containing components impregnated in a liquid (I-2). Here, the components in the liquid are generally solutes contained in a solution. In addition, the solutes can be any of gaseous substances, liquid substances, and solid substances as long as they can be dissolved, dispersed, or the like in a solvent. Note that, in the case where the solute is a liquid substance (for example, under the conditions of 25°C and 1 atm), the liquid substance itself (the liquid substance itself) can be the liquid and the components in the liquid.

[0052] In the process (I-2), the water content of the polarizing film is preferably 22% by weight or more, more preferably 25% by weight or more, from the viewpoint of easily impregnating the components contained in the liquid and easily permeating in the thickness direction of the polarizing film, and the water content of the polarizing film is preferably 70% by weight or less, more preferably 60% by weight or less, from the viewpoint of preventing wrinkles during transportation.

[0053] As the coating method in the process of applying a liquid, existing coating methods can be applied, and for example, roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and blade coating (comma coating, and the like) can be exemplified. Note that, the coated surface of the polarizing film can be one surface or both surfaces.

[0054] From the viewpoint of easily allowing the component to be impregnated in the above water-containing polarizing film, the component in the above liquid can be a water-soluble compound. Note that the above water-soluble compound refers to a compound having a solubility of 1 g or more for 100 g of water at 25 °C.

[0055] As the component in the above liquid, for example, zinc salts (zinc chloride, zinc iodide, and the like; zinc sulfate, zinc acetate, and the like); organic titanium compounds (alkoxy titanium, titanium chelate, titanium chelate ammonium salt, titanium chelate acylate, and the like), organic zirconium (alkoxy zirconium, zirconium chelate, zirconium chelate ammonium salt, zirconium acylate), alkali metal salts, alkaline earth metal salts, metal halides, and the like can be given.

[0056] In addition, as the component in the above liquid, a compound having a radical capturing function (also referred to as a radical capturing agent) can be given. The above compound having a radical capturing function can capture radicals generated from polyvinyl alcohol of the polarizing film due to heating, inhibit polyeneization, and thus can improve the durability of the polarizing film to heat. As the above compound having a radical capturing function, from the viewpoint of being able to easily inhibit polyeneization, for example, a compound having a nitroxyl radical or a nitroxyl group is preferable.

[0057] As the above compound having a nitroxyl radical or a nitroxyl group, for example, a compound having an organic group having the following structure, and the like can be given.

[0058] [Chemical Formula 1]

[0059]

[0060] (In General Formula (1), R 1 represents a nitroxyl radical, R 2 to R 5 independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n represents 0 or 1), and note that the left side of the dotted line in General Formula (1) represents an arbitrary organic group.

[0061] As the compound having the above organic group, for example, a compound represented by General Formulae (2) to (5) below, and the like can be given.

[0062] [Chemical Formula 2]

[0063]

[0064] (In General Formula (2), R 1 to R 5 and n have the same meanings as described above, and R 6 represents a hydrogen atom, or an alkyl group, an acyl group, or an aryl group having 1 to 10 carbon atoms.)

[0065] [Chemical Formula 3]

[0066]

[0067] (in General Formula (3), R 1 ~R 5 and n are the same as described above, and R 7 and R 8 independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an acyl group, or an aryl group.)

[0068] [Chemical Formula 4]

[0069]

[0070] (in General Formula (4), R 1 ~R 5 and n are the same as described above, and R 9 ~R 11 independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an acyl group, an amino group, an alkoxy group, a hydroxyl group, or an aryl group.)

[0071] [Chemical Formula 5]

[0072]

[0073] (in General Formula (5), R 1 ~R 5 and n are the same as described above, and R 12 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an amino group, an alkoxy group, a hydroxyl group, or an aryl group.)

[0074] In General Formulas (1) to (5) described above, from the viewpoint of easiness of acquisition, R 2 ~R 5 are preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. In General Formula (2) described above, from the viewpoint of easiness of acquisition, R 6 is preferably a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, and more preferably a hydrogen atom. In General Formula (3) described above, from the viewpoint of easiness of acquisition, R 7 and R 8 are independently preferably a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, and more preferably a hydrogen atom. In General Formula (4) described above, from the viewpoint of easiness of acquisition, R 9 ~R 11 are preferably a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms. In General Formula (5) described above, from the viewpoint of easiness of acquisition, R 12 is preferably a hydroxyl group, an amino group, or an alkoxy group. In General Formulas (1) to (5) described above, n is preferably 1 from the viewpoint of easiness of acquisition.

[0075] In addition, as the above-mentioned compound having a nitroxyl radical or a nitroxyl group, for example, the following compounds can be mentioned.

[0076] [Chemical Formula 6]

[0077]

[0078] (In General Formula (6), R represents a hydrogen atom, an alkyl group having a carbon number of 1 to 10, an acyl group, or an aryl group.)

[0079] [Chemical Formula 7]

[0080]

[0081] [Chemical Formula 8]

[0082]

[0083] In addition, as the component in the above-mentioned liquid, a compound having a cross-linking function (also referred to as a cross-linking agent) can be mentioned. The above-mentioned compound having a cross-linking function reacts with the hydroxyl group of the polyvinyl alcohol of the polarizing film to form a cross-linking structure, thereby being able to improve the durability of the polarizing film to humidification. As the above-mentioned compound having a cross-linking function, from the viewpoint of improvement of the durability to humidification, in addition to organic compounds having an isocyanate group, an isocyanate-derived functional group, an epoxy group, a carbonyl group, an aziridine ring, a vinyl ether group, a vinyl sulfone group, an oxazoline group, and the like, organic titanium compounds (titanium alkoxide, titanium chelate, titanium chelate ammonium salt, titanium chelate acylate, and the like) and the like can be mentioned. In addition, as the component in the above-mentioned liquid, a compound having a cross-linking function (also referred to as a cross-linking agent) can be mentioned. The above-mentioned compound having a cross-linking function reacts with the hydroxyl group of the polyvinyl alcohol of the polarizing film to form a cross-linking structure, thereby being able to improve the durability of the polarizing film to humidification. As the above-mentioned compound having a cross-linking function, from the viewpoint of improvement of the durability to humidification, in addition to organic compounds having an isocyanate group, an isocyanate-derived functional group, an epoxy group, a carbonyl group, an aziridine ring, a vinyl ether group, a vinyl sulfone group, an oxazoline group, and the like, organic titanium compounds (titanium alkoxide, titanium chelate, titanium chelate ammonium salt, titanium chelate acylate, and the like) and the like can be mentioned.

[0084] In addition, as the component in the above-mentioned liquid, a compound having a plasticizing function (also referred to as a plasticizer) can be mentioned. The above-mentioned compound having a plasticizing function can reduce quality defects such as scratches caused by the force of the press-in by imparting plasticity to the polarizing film. As the above-mentioned compound having a plasticizing function, for example, ethylene glycol, polyethylene glycol, and ethylene glycol derivatives, glycerin, and the like can be mentioned.

[0085] In addition, as the component in the above-mentioned liquid, a dye-based compound (also referred to as a dye) can be mentioned. The above-mentioned dye-based compound can impart the polarizing film with color phase adjustment, pattern printing, and the like. As the above-mentioned dye-based compound, for example, azo compounds, anthraquinone-based compounds, quinophthalone-based compounds, and the like can be mentioned.

[0086] The above liquid is affected by the above coating (applying) form, and therefore, the concentration of the component in the liquid is preferably 0.1% by weight or more, more preferably 1.0% by weight or more, from the viewpoint of being able to impregnate the component in the liquid with good efficiency, and the concentration of the component in the above liquid is preferably 30% by weight or less, more preferably 20% by weight or less, from the viewpoint of preventing quality deterioration caused by the component in the liquid.

[0087] As the above solvent, water; methanol, ethanol, ethylene glycol, polyethylene glycol, and water-soluble solvents such as ethylene glycol derivatives, glycerin, dimethyl sulfoxide, and the like can be exemplified.

[0088] For the time from after the above process (I-1) until the start of the above process (I-2) (transport time of the polarizing film in actual device production), from the viewpoint of maintaining the moisture contained in the polarizing film containing water, or from the viewpoint of productivity, it is preferably 300 seconds or less, more preferably 180 seconds or less, further preferably 60 seconds or less, and more further preferably 10 seconds or less, at a temperature of about 15°C to 35°C, preferably a temperature of about 20°C to 30°C.

[0089] In addition, as necessary, in the above process (I-2), after the process of applying the liquid to the above polarizing film containing water, a process of impregnating a part of the liquid and removing the remaining liquid can be performed. As the method of removing the liquid, a wiping removal method using a cotton swab, a sponge roll, or the like, a suction removal method, a removal method using air blowing, a scraping removal method using a bar, a gravure roll, or the like can be exemplified.

[0090] <Process (I-3) of manufacturing the dried polarizing film>

[0091] The manufacturing method of the polarizing film of the present application includes a process (I-3) of manufacturing a dried polarizing film by performing a drying process on the above obtained polarizing film impregnated with the component in the liquid.

[0092] The above drying process is a process of obtaining a polarizing film by drying the above obtained polarizing film impregnated with the component in the liquid, and a polarizing film having a desired moisture rate can be obtained by drying. The above drying is performed by any appropriate method, and natural drying, air blowing drying, heating drying can be exemplified.

[0093] The temperature of the above drying is preferably about 20 to 150°C, more preferably about 25 to 100°C. In addition, the time of the above drying cannot be determined generally because the degree of drying of the polarizing film is affected by the temperature of the drying, and is preferably about 10 to 600 seconds, more preferably about 30 to 300 seconds. The above drying process can be performed only once, or can be performed a plurality of times as necessary.

[0094] From the viewpoint of preventing quality defects such as scratches accompanying loss of plasticity, the moisture content of the above dried polarizing film is preferably 10% by weight or more, more preferably 12% by weight or more, and from the viewpoint of improving optical properties such as degree of polarization, the moisture content is preferably 20% by weight or less, more preferably 16% by weight or less. Note that in the case of the dried polarizing film having a thickness of about 8 μm or less described later, from the viewpoint of preventing quality defects such as scratches accompanying loss of plasticity, the moisture content of the above dried polarizing film is preferably 2% by weight or more, more preferably 3% by weight or more, and from the viewpoint of improving optical properties such as degree of polarization, the moisture content is preferably 20% by weight or less, more preferably 10% by weight or less.

[0095] The thickness of the above dried polarizing film is preferably about 1 to 30 μm, more preferably about 5 to 25 μm, further preferably about 5 to 20 μm. In particular, in order to obtain a dried polarizing film having a thickness of about 8 μm or less, the following method for producing a thin polarizing film can be used, in which a laminate including a thermoplastic resin substrate and a polyvinyl alcohol-based resin layer formed thereon is used as the above polyvinyl alcohol-based film.

[0096] <Method for producing a polarizing film (thin polarizing film)>

[0097] The method for producing a polarizing film (thin polarizing film) includes: a process (II-0) of preparing a laminate by forming a polyvinyl alcohol-based resin layer including a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate; a process (II-1) of producing a laminate having a polarizing film containing water by performing at least a process of auxiliary stretching in a gaseous atmosphere, a process of dyeing, and a process of stretching in an aqueous solution while conveying the obtained laminate in the longitudinal direction, thereby producing a laminate having a polarizing film containing water; a process (II-2) of producing a laminate having a polarizing film containing components impregnated in a liquid by performing a process of applying a liquid to the obtained laminate having a polarizing film containing water in a state where the moisture content of the polarizing film is 20% by weight or more; and a process (II-3) of producing a dried polarizing film by performing a drying process on the obtained laminate having a polarizing film containing components impregnated in a liquid.

[0098] <Process (II-0) of preparing a laminate>

[0099] The method for producing the polarizing film (thin polarizing film) of the present application includes a step (II-0) of preparing a laminate by forming a polyvinyl alcohol-based resin layer (PVA-based resin layer) containing a polyvinyl alcohol-based resin (PVA-based resin) on one side of a long thermoplastic resin substrate.

[0100] As the method for producing the above-mentioned laminate, any appropriate method can be employed, and examples include a method in which a coating liquid containing the above-mentioned PVA-based resin is applied to the surface of the above-mentioned thermoplastic resin substrate and dried. The thickness of the above-mentioned thermoplastic resin substrate is preferably about 20 to 300 μm, more preferably about 50 to 200 μm. The thickness of the above-mentioned PVA-based resin layer is preferably about 3 to 40 μm, more preferably about 3 to 20 μm.

[0101] The above-mentioned thermoplastic resin substrate absorbs water and greatly reduces the tensile stress, and from the viewpoint of being able to stretch at a high magnification, the water absorption rate is preferably about 0.2% or more, more preferably about 0.3% or more. On the other hand, for the above-mentioned thermoplastic resin substrate, from the viewpoint of being able to prevent a significant decrease in the dimensional stability of the thermoplastic resin substrate and deterioration in the appearance of the resulting polarizing film and the like, the water absorption rate is preferably about 3% or less, more preferably about 1% or less. Note that the above-mentioned water absorption rate can be adjusted, for example, by introducing a modifying group into the material constituting the above-mentioned thermoplastic resin substrate. The above-mentioned water absorption rate is a value obtained based on JIS K 7209.

[0102] For the above-mentioned thermoplastic resin substrate, from the viewpoint of being able to suppress crystallization of the PVA-based resin layer and sufficiently ensure the stretchability of the laminate, the glass transition temperature (Tg) is preferably about 120°C or less. Furthermore, in view of the plasticization of the thermoplastic resin substrate by water and the good stretching in an aqueous solution, the above-mentioned glass transition temperature (Tg) is preferably about 100°C or less, further preferably about 90°C or less. On the other hand, from the viewpoint of being able to prevent deformation of the thermoplastic resin substrate and the like when the coating liquid is applied / dried and produce a good laminate, the glass transition temperature of the thermoplastic resin substrate is preferably about 60°C or more. Note that the above-mentioned glass transition temperature can be adjusted, for example, by introducing a modifying group into the material constituting the above-mentioned thermoplastic resin substrate and heating using a crystallization material. The above-mentioned glass transition temperature (Tg) is a value obtained based on JIS K 7121.

[0103] As the material constituting the above-mentioned thermoplastic resin substrate, any appropriate thermoplastic resin can be used. As the above-mentioned thermoplastic resin, for example, ester resins such as polyethylene terephthalate resins, cyclic olefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, copolymer resins thereof, and the like can be listed. Among these, norbornene resins, amorphous (non-crystalline) polyethylene terephthalate resins are preferred, and further, from the viewpoint of excellent stretchability of the thermoplastic resin substrate and suppression of crystallization during stretching, amorphous (non-crystalline) polyethylene terephthalate resins are preferably used. As the amorphous (non-crystalline) polyethylene terephthalate resins, copolymers containing isophthalic acid and / or cyclohexane dicarboxylic acid as a dicarboxylic acid, copolymers containing cyclohexane dimethanol, diethylene glycol as a diol can be listed.

[0104] The above-mentioned thermoplastic resin substrate can be subjected to surface treatment (e.g., corona treatment) before the formation of the PVA-based resin layer, or an easy-adhesion layer can be formed on the thermoplastic resin substrate. By such treatment, the adhesion between the thermoplastic resin substrate and the PVA-based resin layer can be improved. In addition, the above-mentioned thermoplastic resin substrate can be stretched before the formation of the PVA-based resin layer.

[0105] The above-mentioned coating liquid is a solution obtained by dissolving a PVA-based resin in a solvent. As the above-mentioned solvent, for example, water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, ethylenediamine, diethylenetriamine, amines, and the like can be listed, and water is preferred. These solvents can be used alone or in combination of two or more. From the viewpoint of forming a uniform coating film that adheres to the thermoplastic resin substrate, the concentration of the PVA-based resin in the above-mentioned coating liquid is preferably about 3 to 20 parts by weight per 100 parts by weight of the solvent.

[0106] From the viewpoint of improving the orientation of the polyvinyl alcohol molecules based on stretching, it is preferred to incorporate a halide in the above-mentioned coating liquid. As the above-mentioned halide, any appropriate halide can be used, and for example, iodides and sodium chloride can be listed. As the above-mentioned iodides, for example, potassium iodide, sodium iodide, lithium iodide, and the like can be listed, and potassium iodide is preferred. The concentration of the above-mentioned halide in the above-mentioned coating liquid is preferably about 5 to 20 parts by weight, more preferably about 10 to 15 parts by weight, per 100 parts by weight of the PVA-based resin.

[0107] In addition, an additive can be incorporated in the above-mentioned coating liquid. As the above-mentioned additive, for example, plasticizers such as ethylene glycol, glycerol, and the like; surfactants such as nonionic surfactants, and the like can be listed.

[0108] As the coating method of the above-mentioned coating liquid, any appropriate method can be adopted, and examples thereof include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and blade coating (comma coating, etc.). In addition, the drying temperature of the above-mentioned coating liquid is preferably 50°C or higher.

[0109] <Manufacturing process of the laminate having a polarizing film containing water (II-1)>

[0110] The manufacturing method of the polarizing film (thin polarizing film) of the present application includes: a process (II-1) of manufacturing a laminate having a polarizing film containing water, by transporting the above-mentioned obtained laminate in the longitudinal direction while applying at least a gas atmosphere-assisted stretching treatment process, a dyeing treatment process, and a stretching treatment process in an aqueous solution to the laminate.

[0111] In the above-mentioned gas atmosphere-assisted stretching treatment process, in order to perform stretching while suppressing crystallization of the thermoplastic resin substrate, the laminate can be stretched at a high draw ratio. The stretching method of the above-mentioned gas atmosphere-assisted stretching treatment process can be a fixed-end stretching method (for example, a method of stretching using a tenter stretching machine), or a free-end stretching method (for example, a method of uniaxially stretching the laminate by passing it between rollers having different circumferential speeds). From the viewpoint of obtaining high optical properties, the free-end stretching method is preferred.

[0112] The draw ratio in the above-mentioned gas atmosphere-assisted stretching process is preferably about 2 to 3.5 times. The above-mentioned gas atmosphere-assisted stretching process can be performed in one stage, or in multiple stages. In the case of performing the process in multiple stages, the draw ratio is the product of the draw ratios of the respective stages.

[0113] The stretching temperature in the above-mentioned gas atmosphere-assisted stretching process can be set to any appropriate value depending on the material forming the thermoplastic resin substrate, the stretching method, etc., and is preferably the glass transition temperature (Tg) of the thermoplastic resin substrate or higher, more preferably the glass transition temperature (Tg) + 10°C or higher, and further preferably the glass transition temperature (Tg) + 15°C or higher. On the other hand, from the viewpoint of quickly performing stretching while suppressing crystallization of the PVA-based resin, and suppressing adverse effects (for example, hindering the orientation of the PVA-based resin layer based on stretching) caused by crystallization, the upper limit of the stretching temperature is preferably about 170°C.

[0114] If necessary, the insolubilization treatment step can be performed after the stretching treatment step in the above-mentioned gaseous atmosphere, the dyeing treatment step, or the stretching treatment step in an aqueous solution. The above-mentioned insolubilization treatment step is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing the insolubilization treatment step, water resistance can be imparted to the PVA-based resin layer, and the decrease in orientation of PVA when immersed in water can be prevented. The concentration of the aqueous boric acid solution is preferably about 1 to 5 parts by weight per 100 parts by weight of water. The temperature of the insolubilization treatment bath is preferably about 20 to 50°C.

[0115] The above-mentioned dyeing treatment step is performed by dyeing the PVA-based resin layer with iodine. As the adsorption method, for example, a method in which the PVA-based resin layer (laminate) is immersed in a dyeing solution containing iodine; a method in which the dyeing solution is applied to the PVA-based resin layer; a method in which the dyeing solution is sprayed onto the PVA-based resin layer; and the like can be given, and the method in which the PVA-based resin layer (laminate) is immersed in a dyeing solution containing iodine is preferred.

[0116] The amount of iodine to be added to the dyeing bath is preferably about 0.05 to 0.5 parts by weight per 100 parts by weight of water. In order to increase the solubility of iodine in water, the above-mentioned iodide is preferably added to the aqueous iodine solution. The amount of the above-mentioned iodide to be added is preferably about 0.1 to 10 parts by weight, more preferably about 0.3 to 5 parts by weight, per 100 parts by weight of water. In order to suppress the dissolution of the PVA-based resin, the temperature of the dyeing bath is preferably about 20 to 50°C. In addition, from the viewpoint of ensuring the transmittance of the PVA-based resin layer, the immersion time is preferably about 5 seconds to 5 minutes, more preferably about 30 seconds to 90 seconds. From the viewpoint of obtaining a polarizing film having good optical properties, the ratio of the content of iodine to the content of iodide in the aqueous iodine solution is preferably about 1:5 to 1:20, more preferably about 1:5 to 1:10.

[0117] If necessary, the crosslinking treatment step can be performed after the dyeing treatment step and before the stretching treatment step in an aqueous solution. The above-mentioned crosslinking treatment step is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing the crosslinking treatment step, water resistance can be imparted to the PVA-based resin layer, and the decrease in orientation of PVA when immersed in high-temperature water in the subsequent stretching in an aqueous solution can be prevented. The concentration of boric acid in the aqueous boric acid solution is preferably about 1 to 5 parts by weight per 100 parts by weight of water. In addition, in the case where the crosslinking treatment step is performed, it is preferred that the above-mentioned iodide be further added to the crosslinking bath. By adding the above-mentioned iodide, the elution of iodine adsorbed to the PVA-based resin layer can be suppressed. The amount of the above-mentioned iodide to be added is preferably about 1 to 5 parts by weight per 100 parts by weight of water. The temperature of the crosslinking bath (aqueous boric acid solution) is preferably about 20 to 50°C.

[0118] The water-solution-in-stretching process is performed by immersing the laminate in a stretching bath. According to the water-solution-in-stretching process, the stretching can be performed at a temperature lower than the glass transition temperature of the thermoplastic resin base material and the PVA-based resin layer (typically about 80°C), and the stretching can be performed at a high magnification while suppressing crystallization of the PVA-based resin layer. The stretching method of the water-solution-in-stretching process can be fixed-end stretching (for example, a method of stretching using a tenter stretching machine) or free-end stretching (for example, a method of uniaxially stretching by passing the laminate between rollers having different circumferential speeds), and free-end stretching is preferred from the viewpoint of obtaining high optical properties.

[0119] The water-solution-in-stretching process is preferably performed by immersing the laminate in an aqueous boric acid solution (boric acid water-solution-in-stretching). By using an aqueous boric acid solution as the stretching bath, the PVA-based resin layer can be imparted with rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water. The concentration of boric acid in the aqueous boric acid solution is preferably 1 to 10 parts by weight and more preferably 2.5 to 6 parts by weight, relative to 100 parts by weight of water. In addition, an iodide can be incorporated in the stretching bath (aqueous boric acid solution). The liquid temperature of the stretching bath is preferably about 40 to 85°C and more preferably about 60 to 75°C. The immersion time of the laminate in the stretching bath is preferably about 15 seconds to 5 minutes.

[0120] The stretching magnification in the water-solution-in-stretching process is preferably about 1.5 times or more and more preferably about 3 times or more.

[0121] Note that the total stretching magnification of the laminate relative to the original length of the laminate is preferably about 5 times or more and more preferably about 5.5 times or more.

[0122] The cleaning process is preferably performed after the water-solution-in-stretching process. The cleaning process is typically performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

[0123] In addition, an additive such as a zinc salt, a pH adjuster, a pH buffer, and other salts can be contained in each of the above-described dyeing treatment step, the above-described water-soluble solution stretching treatment step, the above-described insolubilization treatment step, the above-described cross-linking treatment step, and the above-described cleaning treatment step. As the above-described zinc salt, for example, a halogenated zinc such as zinc chloride and zinc iodide; an inorganic zinc salt such as zinc sulfate and zinc acetate; and the like can be exemplified. As the above-described pH adjuster, for example, a strong acid such as hydrochloric acid, sulfuric acid, and nitric acid; a strong base such as sodium hydroxide and potassium hydroxide; and the like can be exemplified. As the above-described pH buffer, for example, a carboxylic acid such as acetic acid, oxalic acid, and citric acid and a salt thereof; an inorganic weak acid such as phosphoric acid and carbonic acid and a salt thereof; and the like can be exemplified. As the above-described other salts, for example, a chloride such as sodium chloride, potassium chloride, and barium chloride; a nitrate such as sodium nitrate and potassium nitrate; a sulfate such as sodium sulfate and potassium sulfate; and a salt of an alkali metal and an alkaline earth metal; and the like can be exemplified.

[0124] <Manufacturing process of a laminate having a polarizing film with components impregnated in a liquid (II-2)>

[0125] The manufacturing method of the polarizing film (thin polarizing film) of the present application includes the above-described process (II-2) of manufacturing a laminate having a polarizing film with components impregnated in a liquid by applying a liquid to the obtained laminate having a polarizing film with water in a state where the moisture content of the polarizing film is 20% by weight or more. For the process (II-2), the above-described process (I-2) of manufacturing a polarizing film with components impregnated in a liquid can be applied in its entirety, in which the liquid is applied to one side of the polarizing film.

[0126] In the above-described process (II-2), from the viewpoint of easily impregnating the components contained in the liquid and more easily permeating in the thickness direction of the polarizing film, it is preferable that the moisture content of the polarizing film be 22% by weight or more, more preferably 25% by weight or more, and from the viewpoint of preventing wrinkles during transportation, it is preferable that the moisture content of the polarizing film be 70% by weight or less, more preferably 60% by weight or less.

[0127] For the time from after the above-described process (II-1) until the start of the above-described process (II-2) (the transportation time of the laminate having a polarizing film in actual equipment manufacturing), from the viewpoint of maintaining the moisture contained in the polarizing film with water or from the viewpoint of productivity, it is preferable that the temperature be about 15°C to 35°C, preferably about 20°C to 30°C, and it is preferable that the time be 300 seconds or less, more preferably 180 seconds or less, further preferably 60 seconds or less, and still further preferably 10 seconds or less.

[0128] <Process of manufacturing a dried polarizing film (II-3)>

[0129] The manufacturing method of the polarizing film (thin polarizing film) of the present application includes a drying treatment step of the obtained layered body having the polarizing film with components impregnated in a liquid, thereby manufacturing a dried polarizing film (II-3).

[0130] The drying treatment step is performed by any appropriate method, and examples thereof include natural drying, air blowing drying, and heating drying. The drying treatment step can be performed by area heating in which the entire area is heated, or by heating the conveyance roll (using a so-called heated roll). By using a heated roll, heating curling of the layered body can be efficiently suppressed, thereby manufacturing a polarizing film having an excellent appearance, and the layered body can be dried while being maintained in a flat state, so that curling and generation of wrinkles can be suppressed. In addition, from the viewpoint of improving the optical properties of the obtained polarizing film by shrinking in the width direction during the drying treatment step, the shrinkage rate in the width direction of the layered body by the drying treatment step is preferably about 1 to 10%, and more preferably about 2 to 8%.

[0131] The drying conditions can be controlled by adjusting the heating temperature of the conveyance roll (temperature of the heated roll), the number of heated rolls, and the contact time with the heated roll. The temperature of the heated roll is preferably about 60 to 120°C, more preferably about 65 to 100°C, and further preferably about 70 to 80°C. From the viewpoint of being able to increase the crystallinity of the thermoplastic resin and suppress curling, the conveyance roll is usually provided at about 2 to 40, and preferably about 4 to 30. The contact time of the layered body with the heated roll (total contact time) is preferably about 1 to 300 seconds, more preferably about 1 to 20 seconds, and further preferably about 1 to 10 seconds.

[0132] The heated roll can be provided in a heating furnace or in a general manufacturing line (in a room temperature environment), and is preferably provided in a heating furnace equipped with an air blowing mechanism. By using a combination of drying using a heated roll and hot air drying, the temperature change between the heated rolls can be suppressed, and the shrinkage in the width direction can be easily controlled. The temperature of the hot air drying is preferably about 30 to 100°C. In addition, the hot air drying time is preferably about 1 to 300 seconds.

[0133]

[0134] The manufacturing method of the polarizing film of the present application includes a step of bonding a transparent protective film to at least one side of the polarizing film obtained by the above manufacturing method of a polarizing film via an adhesive layer.

[0135] ​The transparent protective film is not particularly limited, and various transparent protective films used in polarizing films can be used. As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like can be used. As the thermoplastic resin, for example, cellulose ester-based resins such as cellulose triacetate, polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone-based resins, polysulfone-based resins, polycarbonate-based resins, polyamides such as nylon and aramid, polyimide-based resins, polyolefins such as polyethylene and polypropylene, ethylene-propylene copolymers, (meth)acrylic-based resins, cyclic or cyclic polyolefin-based resins having a norbornene structure (norbornene-based resins), polyarylate-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, and mixtures thereof can be exemplified. In addition, the transparent protective film can use a cured layer formed of a thermosetting resin such as a (meth)acrylic-based resin, a urethane-based resin, an acryl urethane-based resin, an epoxy-based resin, a silicone-based resin, or an ultraviolet-curable resin. Among these, cellulose ester-based resins, polycarbonate-based resins, (meth)acrylic-based resins, cyclic polyolefin-based resins, and polyester-based resins are preferable.

[0136] The thickness of the transparent protective film can be appropriately determined, and in general, from the viewpoints of strength, handleability, thinness, and the like, it is preferably about 1 to 500 μm, more preferably about 1 to 300 μm, and further preferably about 5 to 100 μm.

[0137] When the transparent protective film is attached to both surfaces of the polarizing film, the transparent protective films on the both surfaces can be the same or different.

[0138] The transparent protective film can use a phase difference plate having a front surface phase difference of 40 nm or more and / or a thickness direction phase difference of 80 nm or more. The front surface phase difference is generally controlled to a range of 40 to 200 nm, and the thickness direction phase difference is generally controlled to a range of 80 to 300 nm. When a phase difference plate is used as the transparent protective film, the phase difference plate also functions as a transparent protective film, and thus thinning can be achieved.

[0139] As the phase difference plate, for example, a birefringent film obtained by uniaxially or biaxially stretching a high molecular raw material, an oriented film of a liquid crystal polymer, a phase difference plate obtained by supporting an oriented layer of a liquid crystal polymer with a film, and the like can be exemplified. The thickness of the phase difference plate is not particularly limited, and is generally about 20 to 150 μm. Note that the phase difference plate can be used by being attached to a transparent protective film having no phase difference.

[0140] Any appropriate additive such as an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloration-preventing agent, a flame retardant, an antistatic agent, a pigment, a colorant, and the like can be contained in the above transparent protective film.

[0141] A functional layer such as a hard coat layer, an antireflection layer, an antiadhesion layer, a diffusion layer, an antiglare layer, and the like can be provided on the side of the above transparent protective film which is not bonded to the polarizing film. Note that the above functional layer such as a hard coat layer, an antireflection layer, an antiadhesion layer, a diffusion layer, an antiglare layer, and the like can be provided as a layer other than the protective film itself.

[0142] The above polarizing film and the above transparent protective film, or the above polarizing film and the above functional layer are typically attached to each other with an adhesive layer or a bonding agent layer interposed therebetween.

[0143] As the adhesive for forming the above adhesive layer, various adhesives used in polarizing films can be used, and examples thereof include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl pyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, and the like. Among these, an acrylic adhesive is preferred.

[0144] As the method for forming the adhesive layer, a method in which the above adhesive is applied to a separator or the like subjected to a release treatment and dried to form an adhesive layer, and then transferred to a polarizing film or the like, or a method in which the above adhesive is applied to a polarizing film or the like and dried to form an adhesive layer, and the like can be exemplified. The thickness of the above adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, and preferably about 2 to 50 μm.

[0145] As the bonding agent for forming the above bonding agent layer, various bonding agents used in polarizing films can be used, and examples thereof include isocyanate-based bonding agents, polyvinyl alcohol-based bonding agents, gelatin-based bonding agents, vinyl-based latexes, water-based polyesters, and the like. These bonding agents are typically used in the form of a bonding agent formed from an aqueous solution, and contain 0.5 to 60% by weight of a solid component.

[0146] As the above-mentioned adhesive, in addition to the above, an active energy ray-curable adhesive such as an ultraviolet-curable adhesive, an electron beam-curable adhesive, and the like can be cited. As the above-mentioned active energy ray-curable adhesive, a (meth)acrylate-based adhesive can be cited, for example. As the curable component in the above-mentioned (meth)acrylate-based adhesive, a compound having a (meth)acryloyl group, a compound having a vinyl group, and the like can be cited. In addition, as a cationic polymerization-curable adhesive, a compound having an epoxy group, an oxetanyl group, and the like can also be used. The compound having an epoxy group is not particularly limited as long as it is a compound having at least two epoxy groups in the molecule, and various curable epoxy compounds generally known can be used.

[0147] The coating of the above-mentioned adhesive can be performed on either side of the above-mentioned transparent protective film side (or the above-mentioned functional layer side), the above-mentioned polarizing film side, or both sides. After the lamination, a drying process is performed to form an adhesive layer made of a coated and dried layer. After the above-mentioned drying process, ultraviolet rays, electron beams, and the like can be irradiated as needed. The thickness of the above-mentioned adhesive layer is not particularly limited, and in the case of using a water-based adhesive and the like, it is preferably around 30 to 5000 nm, more preferably around 100 to 1000 nm, and in the case of using an ultraviolet-curable adhesive, an electron beam-curable adhesive, and the like, it is preferably around 0.1 to 100 μm, more preferably around 0.5 to 10 μm.

[0148] The above-mentioned transparent protective film and the above-mentioned polarizing film, or the above-mentioned polarizing film and the above-mentioned functional layer can be laminated together with a spacer layer such as a surface modification treatment layer, an easy-adhesion layer, a barrier layer, a refractive index adjustment layer, and the like interposed therebetween.

[0149] As the surface modification treatment for forming the above-mentioned surface modification layer, a corona treatment, a plasma treatment, a primer treatment, a saponification treatment, and the like can be cited, for example.

[0150] As the easy-adhesion agent for forming the above-mentioned easy-adhesion layer, a forming material containing various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like can be cited, for example. The above-mentioned easy-adhesion layer can be generally provided in advance to a protective film, and the easy-adhesion layer side of the protective film can be laminated with a polarizing film with the above-mentioned adhesive layer or the above-mentioned adhesive layer interposed therebetween.

[0151] The above-mentioned barrier layer is a layer having a function of preventing the movement (invasion) of impurities such as oligomers, ions, and the like dissolved from the transparent protective film and the like into the polarizing film. The above-mentioned barrier layer is a layer having transparency and capable of preventing the impurities dissolved from the transparent protective film and the like, and as a material for forming the barrier layer, a urethane prepolymer-based forming material, a cyanoacrylate-based forming material, an epoxy-based forming material, and the like can be cited, for example.

[0152] The refractive index adjusting layer is a layer provided to suppress a decrease in transmittance accompanying reflection between layers having different refractive indexes, such as the transparent protective film and the polarizing film. As a refractive index adjusting material forming the refractive index adjusting layer, for example, a forming material containing various resins such as silica-based, acrylic-based, acrylic-styrene-based, melamine-based, and additives can be exemplified.

[0153] The degree of polarization of the polarizing film is preferably 99.98% or more, and more preferably 99.99% or more.

[0154] Examples

[0155] Hereinafter, the present application will be described in more detail by citing examples, but the present application is not limited to only these examples.

[0156] Example 1

[0157] Manufacture of Polarizing Film

[0158] Manufacture of Polarizing Film Containing Water (I-1)

[0159] A polyvinyl alcohol film having an average polymerization degree of 2400, a saponification degree of 99.9 mol%, and a thickness of 45 μm was prepared. The polyvinyl alcohol film was immersed in a swelling bath (water bath) at 20°C between rolls having different circumferential speeds for 30 seconds to swell, and at the same time, was stretched 2.2 times in the conveying direction (swelling step), and then was immersed in a dyeing bath (an aqueous solution having an iodine concentration of 0.03% by weight and a potassium iodide concentration of 0.3% by weight) at 30°C for 30 seconds, and at the same time, was stretched 3.3 times in the conveying direction with the original polyvinyl alcohol film (a polyvinyl alcohol film not stretched at all in the conveying direction) as a reference (dyeing step). Subsequently, the dyed polyvinyl alcohol film was immersed in a crosslinking bath (an aqueous solution having a boric acid concentration of 3.0% by weight and a potassium iodide concentration of 3.0% by weight) at 40°C for 28 seconds, and was stretched to 3.6 times in the conveying direction with the original polyvinyl alcohol film as a reference (crosslinking step). Further, the obtained polyvinyl alcohol film was immersed in a stretching bath (an aqueous solution having a boric acid concentration of 4.0% by weight and a potassium iodide concentration of 5.0% by weight) at 61°C for 60 seconds, and was stretched to 6.0 times in the conveying direction with the original polyvinyl alcohol film as a reference (stretching step), and then was immersed in a washing bath (an aqueous solution having a potassium iodide concentration of 2.0% by weight) at 20°C for 5 seconds (washing step), to manufacture a polarizing film containing water.

[0160] Manufacture of Polarizing Film Containing Components Immersed in Liquid (I-2)

[0161] A liquid A (10% by weight of an aqueous solution of a compound represented by Chemical Formula (9) described below) was applied to the above-obtained water-containing polarizing film using a wire bar (No. 3 manufactured by the First Science Co., Ltd.), and after standing for 3 seconds at 25°C, the surface of the liquid A remaining was wiped off, to produce a polarizing film impregnated with the components in the liquid. Here, the moisture content of the water-containing polarizing film was 33.0% by weight, which was determined by the following measurement method.

[0162] [Chemical Formula 9]

[0163]

[0164] [Measurement method of the moisture content (%) in the polarizing film]

[0165] About 0.2 g of the polarizing film was weighed and dried at 120°C for 2 hours, and the weight after drying was measured, and the moisture content (W) in the polarizing film was calculated based on the following formula.

[0166] Moisture content W (%) of the polarizing film = {(M0 - M1) / M0} x 100

[0167] M0: Weight (g) of the weighed polarizing film

[0168] M1: Weight (g) of the polarizing film after drying at 120°C for 2 hours

[0169] <Manufacture of the polarizing film after drying (I-3)>

[0170] The above-obtained polarizing film impregnated with the components in the liquid was dried at 60°C for 4 minutes, to produce a polarizing film after drying (hereinafter also referred to simply as a polarizing film). The moisture content of the polarizing film after drying was 11.3% by weight, which was determined by the above measurement method. The content of the compound represented by Chemical Formula (9) in the polarizing film (M H ) was 0.27% by weight, and the content of the compound represented by Chemical Formula (9) per unit area (m H ) was 5.8 μg / cm 2 , which were determined by the following measurement method. In addition, the thickness (T) of the polarizing film was 18 μm.

[0171] [Measurement method of the content (%) of the compound represented by Chemical Formula (9) in the polarizing film]

[0172] About 20 mg of the polarizing film was weighed and quantified, and after heating and dissolving in 1 mL of water, the obtained solution was diluted with 4.5 mL of methanol, and the obtained extract was filtered using a membrane filter, and the concentration of the compound represented by Chemical Formula (9) was measured using HPLC (ACQUITY UPLC H-class Bio manufactured by Waters Corporation) for the filtrate.

[0173] [Method for measuring the content (μg / cm2) of the compound represented by formula (9) in the polarizing film per unit area] 2 ) of the compound represented by formula (9) in the polarizing film per unit area.

[0174] The content (m H ) of the compound represented by formula (9) per unit area was calculated based on the following formula.

[0175] m H = 1.2 x T x M H (μg / cm 2 )

[0176] T: thickness of the polarizing film (μm)

[0177] M H : content (wt%) of the compound represented by formula (9) in the polarizing film

[0178] <Manufacture of polarizing film>

[0179] As the adhesive, an aqueous solution containing a polyvinyl alcohol resin having acetyl acetyl groups (average degree of polymerization: 1200, saponification degree: 98.5 mol%, acetyl acetyl degree: 5 mol%) and a methylol melamine at a weight ratio of 3: 1 was used. After the adhesive was used and a cellulose triacetate film (moisture permeability: 342 g / (m 2 ·24h), Konica Minolta, trade name "KC4UYW") having a hard coat layer and a thickness of 40 μm was laminated to both sides of the above-obtained polarizing film using a roll laminator, the laminate was then heated and dried in an oven (temperature: 60°C, time: 4 minutes), and a polarizing film in which transparent protective films were laminated to both sides of the polarizing film was manufactured.

[0180] [Method for measuring degree of polarization]

[0181] The degree of polarization of the polarizing film can be measured using a spectrophotometer (Nippon Denshoku, product name "V7100"). As a specific measurement method for the degree of polarization, the parallel transmittance (H0) and the orthogonal transmittance (H90) of the polarizing film can be measured, and the degree of polarization (%) can be calculated according to the formula: degree of polarization (%) = {(H0 - H90) / (H0 + H90)}1 / 2x 100. The parallel transmittance (H0) is the value of the transmittance of a parallel-type laminated polarizing film produced by laminating two identical polarizing films such that the absorption axes of the two films are parallel. In addition, the orthogonal transmittance (H90) is the value of the transmittance of an orthogonal-type laminated polarizing film produced by laminating two identical polarizing films such that the absorption axes of the two films are orthogonal. Note that these transmittances are Y values obtained by performing visibility correction using the 2-degree field (C light source) of JIS Z8701-1982.

[0182] [Heat resistance evaluation (A)]

[0183] The polarizing film obtained above was cut into a size of 5.0 x 4.5 cm with the absorption axis of the polarizing film parallel to the long side, and a glass plate (a simulated image display unit) was attached to the protective film side of the polarizing film with a 20-μm-thick acrylic pressure-sensitive adhesive layer interposed therebetween, and a laminate was produced by autoclave treatment at 50°C and 0.5 MPa for 15 minutes. The obtained laminate was left in a hot-air oven at 110°C, and the time until coloring was observed with the naked eye, and the results were evaluated according to the following criteria.

[0184] O: No coloring occurred for 500 hours or more.

[0185] Δ: Coloring occurred for 300 hours or more and less than 500 hours.

[0186] X: Coloring occurred for less than 300 hours.

[0187] Example 2

[0188] Manufacture of Polarizing Film and Polarizer

[0189] The polarizing film after the cleaning step was left to stand at 25°C for 30 seconds, and the polarizing film containing water was obtained, and then liquid A was applied. Otherwise, the polarizing film and the polarizer were produced by the same procedure as in Example 1, and the above-described measurement was performed. The results are shown in Table 1.

[0190] Example 3

[0191] Manufacture of Polarizing Film and Polarizer

[0192] The polarizing film after the cleaning step was left to stand at 25°C for 1 minute, and the polarizing film containing water was obtained, and then liquid A was applied. Otherwise, the polarizing film and the polarizer were produced by the same procedure as in Example 1, and the above-described measurement was performed. The results are shown in Table 1.

[0193] Comparative Example 1

[0194] Manufacture of Polarizing Film and Polarizer

[0195] The polarizing film after the cleaning step was left to stand at 25°C for 3 minutes, and the polarizing film containing water was obtained, and then liquid A was applied. Otherwise, the polarizing film and the polarizer were produced by the same procedure as in Example 1, and the above-described measurement was performed. The results are shown in Table 1.

[0196] Comparative Example 2

[0197] Manufacture of Polarizing Film and Polarizer

[0198] The polarizing film after the cleaning step was left to stand at 60°C for 1 minute, and then coated with Liquid A. Otherwise, the polarizing film and polarizing film were produced by the same procedure as in Example 1, and the above-described measurements were performed. The results are shown in Table 1.

[0199] Example 4

[0200] Manufacture of Polarizing Film and Polarizing Film

[0201] The polarizing film after the cleaning step was left to stand at 60°C for 1 minute, and then coated with Liquid A. Otherwise, the polarizing film and polarizing film were produced by the same procedure as in Example 1, and the above-described measurements were performed. The results are shown in Table 1. Note that the thickness (T) of the polarizing film was 12 μm.

[0202] [Heat Durability Evaluation (B)]

[0203] The polarizing film obtained above was cut into a size of 5.0 x 4.5 cm with the absorption axis of the polarizing film parallel to the long side, and a glass plate (simulated image display unit) was attached to the protective film side of the polarizing film with a 20-μm-thick acrylic adhesive layer interposed therebetween, and a laminate was produced by autoclave treatment at 50°C and 0.5 MPa for 15 minutes. The obtained laminate was left to stand in a hot-air oven at a temperature of 105°C, and the time until coloring occurred was observed with the naked eye, and the evaluation was performed based on the following criteria.

[0204] O: No coloring occurred for 750 hours or more.

[0205] Δ: Coloring occurred for 500 hours or more and less than 750 hours.

[0206] X: Coloring occurred for less than 500 hours.

[0207] Comparative Example 3

[0208] Manufacture of Polarizing Film and Polarizing Film

[0209] The polarizing film after the cleaning step was left to stand at 60°C for 1 minute, and then coated with Liquid A. Otherwise, the polarizing film and polarizing film were produced by the same procedure as in Example 1, and the above-described measurements were performed. The results are shown in Table 1. Note that the thickness (T) of the polarizing film was 12 μm.

[0210] Example 5

[0211] Manufacture of Polarizing Film

[0212] Manufacture of Laminate (Preparation) (II-0)

[0213] As the thermoplastic resin base material, an amorphous copolymerized isophthalic acid polyethylene terephthalate film (thickness: 100 μm) having a length of 1000 mm, a width of 100 mm, a water absorption of 0.75%, and a Tg of about 75°C was used. One side of the resin base material was subjected to a corona treatment. A PVA aqueous solution (coating solution) was prepared by adding 13 parts by weight of potassium iodide to 100 parts by weight of a PVA-based resin obtained by mixing 9 parts by weight of polyvinyl alcohol (degree of polymerization: 4200, saponification degree: 99.2 mol%) and 1 part by weight of acetyl acetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410"). The PVA aqueous solution was coated on the corona-treated side of the resin base material, and dried at 60°C to form a PVA-based resin layer having a thickness of 13 μm, thereby producing (preparing) a laminate.

[0214] <Manufacture of laminate having a polarizing film containing water (II-1)>

[0215] The obtained laminate was subjected to free-end uniaxial stretching (stretching treatment process in a gas atmosphere) to 2.4 times in the longitudinal direction (lengthwise direction) at different circumferential speeds of the rollers in an oven at 130°C. Next, the laminate was immersed in a liquid temperature of 40°C insolubilization bath (boric acid aqueous solution obtained by adding 4 parts by weight of boric acid to 100 parts by weight of water) for 30 seconds (insolubilization treatment process). Next, the laminate was immersed in a liquid temperature of 30°C dyeing bath (aqueous iodine solution obtained by adding iodine and potassium iodide at a weight ratio of 1:7 to 100 parts by weight of water) for 60 seconds while adjusting the concentration in such a manner that the monomer transmittance (Ts) of the finally obtained polarizing film becomes the same degree (dyeing treatment process). Next, the laminate was immersed in a liquid temperature of 40°C crosslinking bath (aqueous boric acid solution obtained by adding 3 parts by weight of potassium iodide and 5 parts by weight of boric acid to 100 parts by weight of water) for 30 seconds (crosslinking treatment process). Then, the laminate was immersed in a liquid temperature of 70°C boric acid aqueous solution (boric acid concentration: 4.0% by weight) while being subjected to uniaxial stretching in the longitudinal direction (lengthwise direction) at different circumferential speeds of the rollers in such a manner that the total stretching ratio becomes 5.5 times (stretching treatment process in an aqueous solution). Then, the laminate was immersed in a liquid temperature of 20°C washing bath (aqueous solution obtained by adding 4 parts by weight of potassium iodide to 100 parts by weight of water) to produce a laminate having a polarizing film containing water (washing treatment process).

[0216] <Manufacture of laminate having a polarizing film containing water (II-1)>

[0217] Using a wire bar (manufactured by the First Science Co., Ltd., No. 3), liquid A (10% by weight aqueous solution of the compound represented by Chemical Formula (9)) was applied to the polarizing film side of the obtained layered body having a polarizing film containing water, and after standing for 3 seconds at 25°C, the liquid A remaining on the surface was wiped off, to produce a layered body having a polarizing film impregnated with the components in the liquid. Here, the moisture content of the polarizing film containing water was 35.5% by weight, as determined by the above-described measurement method.

[0218] <Manufacture of dried polarizing film (II-3)>

[0219] Drying was performed in an oven maintained at 95°C for 10 minutes (drying treatment step). In this way, a polarizing film having a thickness of 5 μm was formed on the resin substrate. The moisture content of the dried polarizing film was 9.9% by weight, as determined by the above-described measurement method. The content of the compound represented by Chemical Formula (9) in the polarizing film (M H ) was 0.41% by weight, and the content of the compound represented by Chemical Formula (9) per unit area (m H ) was 2.5 μg / cm 2 .

[0220] <Manufacture of polarizing film>

[0221] As the adhesive, an aqueous solution containing an acetoacetyl group-containing polyvinyl alcohol resin (average degree of polymerization: 1200, saponification degree: 98.5 mol%, acetoacetyl group degree: 5 mol%) and methylol melamine at a weight ratio of 3: 1 was used. Using this adhesive and a roll laminator, a cellulose triacetate film (moisture permeability: 342 g / (m 2 ·24 h), manufactured by Konica Minolta, trade name "KC4UYW") having a hard coat layer with a thickness of 40 μm was laminated to the side opposite to the resin substrate of the above-obtained polarizing film, and then heat-dried in an oven (temperature: 60°C, time: 4 minutes), to produce a polarizing film having a transparent protective film laminated to one side of the polarizing film. Next, the resin substrate was peeled off, and using the above-described adhesive and a roll laminator, the above-described cellulose triacetate film was laminated to the peeled side, and then heat-dried in an oven (temperature: 60°C, time: 4 minutes), to produce a polarizing film having a transparent protective film laminated to both sides of the polarizing film.

[0222] [Heat resistance evaluation (C)]

[0223] The polarizing film obtained above was cut into a size of 5.0 x 4.5 cm with the absorption axis of the polarizing film parallel to the long side, and a glass plate (simulated image display unit) was attached to the protective film side of the polarizing film with an acrylic adhesive layer of 20 μm in thickness interposed therebetween, and a laminate was produced by autoclave treatment at 50°C and 0.5 MPa for 15 minutes. The obtained laminate was left in a hot air oven at 95°C, and the time until coloring was observed with the naked eye, and the evaluation was performed according to the following criteria.

[0224] O: No coloring occurred for 750 hours or more.

[0225] Δ: Coloring occurred for 500 hours or more and less than 750 hours.

[0226] X: Coloring occurred for less than 500 hours.

[0227] <Comparative Example 4>

[0228] <Manufacture of Polarizing Film and Polarizing Film>

[0229] After the polarizing film after the cleaning treatment step was dried at 95°C for 10 minutes, liquid A was applied, and otherwise, the polarizing film and the polarizing film were produced by the same operation as in Example 5, and the above measurement was performed. The results are shown in Table 3.

[0230] <Example 6>

[0231] <Manufacture of Polarizing Film and Polarizing Film>

[0232] In the manufacture of the polarizing film, the potassium iodide concentration of the cleaning bath was set to 4.0% by weight, and liquid B (an aqueous solution containing zinc sulfate 7 hydrate 10% by weight and Olfine EXP.4200 (manufactured by Nippon Shokubai Co., Ltd.) 0.2% by weight) was used instead of liquid A, and otherwise, the polarizing film and the polarizing film were produced by the same operation as in Example 1, and the above and below measurements were performed. The results are shown in Table 4.

[0233] [Measurement of the Content of Zinc (wt%) in the Polarizing Film]

[0234] About 25 mg of the polarizing film was weighed in a Teflon (registered trademark) container, acid was added and tightly capped, and pressure acid decomposition was performed by irradiation of microwaves at a maximum of 200°C. After complete decomposition, ultrapure water was added, and the volume was made 50 mL, and the zinc concentration was measured using ICP-MS (Agilent 8800 manufactured by Agilent Technologies). The decomposition device used was MARS5 manufactured by CEM.

[0235] [Heat Durability Evaluation (D)]

[0236] The polarizing film obtained above was cut into a size of 5.0 x 4.5 cm with the absorption axis of the polarizing film parallel to the long side, and a glass plate (a simulated image display unit) was attached to the protective film side of the polarizing film with an acrylic adhesive layer of 20 μm in thickness interposed therebetween, and a laminate was produced by autoclave treatment at 50°C and 0.5 MPa for 15 minutes. The laminate obtained was left in a hot air oven at 105°C for 500 hours, and the sample after the test was arranged in a crossed-Nicol manner, and the crossed transmittance (%) at a wavelength of 700 nm was measured by the spectrophotometer (V7100) described above, and the results were judged based on the following criteria.

[0237] O: No heating reddening (difference in crossed transmittance at a wavelength of 700 nm before and after the heating test at 105°C for 500 hours was less than 1%).

[0238] X: Heating reddening (difference in crossed transmittance at a wavelength of 700 nm before and after the heating test at 105°C for 500 hours was 1% or more).

[0239] <Comparative Example 5>

[0240] <Manufacture of Polarizing Film and Polarizing Film>

[0241] The polarizing film after the cleaning step was dried at 60°C for 1 minute, and then liquid B was applied thereto, and otherwise, the polarizing film and the polarizing film were produced by the same procedure as in Example 6, and the measurements described above were performed. The results are shown in Table 4.

[0242]

[0243]

[0244]

[0245]

[0246] The heating durability test described above is affected by the film thickness of the polarizing film, and therefore, when polarizing films having the same degree of film thickness are compared with each other, it is found that the polarizing film of the example contains the components in the liquid more sufficiently than the polarizing film of the comparative example, and therefore, the heating durability is more excellent.

Claims

1. A method for producing a polarizing film, the method comprising: process (I-l): producing a water-containing polarizing film by carrying out at least a dyeing process, a crosslinking process, a stretching process, and a cleaning process on a polyvinyl alcohol-based film while transporting the polyvinyl alcohol-based film in a length direction; process (I-2): producing a polarizing film containing components of a liquid by carrying out a process of applying a liquid on the water-containing polarizing film obtained in the process (I-l) in a state where a moisture content of the polarizing film is 20% by weight or more; process (I-3): producing a dried polarizing film by carrying out a drying process on the polarizing film containing the components of the liquid obtained in the process (I-2); and process (I-4): producing a transparent protective film-attached polarizing film by applying an adhesive on the liquid-applied surface of the dried polarizing film obtained in the process (I-3) and laminating a transparent protective film via the adhesive layer, wherein the water-containing polarizing film is kept at a temperature of 15°C to 35°C for 60 seconds or less from after the process (I-l) until the process (I-2) is started, or the method comprises: process (II-0): preparing a laminate by forming a polyvinyl alcohol-based resin layer containing a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate; process (II-l): producing a laminate having a water-containing polarizing film by carrying out at least a process of assisting a stretching treatment in a gas atmosphere, a dyeing treatment process, a process of stretching treatment in an aqueous solution, and a cleaning treatment process on the obtained laminate while transporting the laminate in a length direction; process (II-2): producing a laminate having a polarizing film containing components of a liquid by carrying out a process of applying a liquid on the laminate having the water-containing polarizing film obtained in the process (II-l) in a state where a moisture content of the polarizing film is 20% by weight or more; process (II-3): producing a laminate having a dried polarizing film by carrying out a drying treatment process on the laminate having the polarizing film containing the components of the liquid obtained in the process (II-2); and process (II-4): producing a transparent protective film-attached polarizing film by applying an adhesive on the liquid-applied surface of the dried polarizing film obtained in the process (II-3) and laminating a transparent protective film via the adhesive layer, wherein the water-containing polarizing film is kept at a temperature of 15°C to 35°C for 60 seconds or less from after the process (II-l) until the process (II-2) is started.

2. The method for producing a polarizing film according to claim 1, wherein the liquid is a solution, and the components in the liquid are solutes.

3. The method for producing a polarizing film according to claim 1 or 2, wherein a moisture content of the dried polarizing film is 20% by weight or less.

4. The method for producing a polarizing film according to claim 1 or 2, wherein the components in the liquid are water-soluble compounds.

5. The method for producing a polarizing film according to claim 1 or 2, wherein the components in the liquid are at least one selected from the group consisting of a radical scavenger, a crosslinking agent, a plasticizer, and a dye.

6. The method for producing a polarizing film according to claim 1 or 2, wherein the components in the liquid are a radical scavenger. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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