polarizing film

Abstract

This invention provides a polarizing film, which is a polarizing film on at least one side of a polarizing film with a transparent protective film or an optical functional film attached thereto. The polarizing film is formed by adsorbing iodine onto a polyvinyl alcohol film and orienting it, and the iodine concentration exceeds 10% by weight. The transparent protective film or the optical functional film has a moisture transmittance of 200 g / (m²). 2 The first film (within 24 hours) has a single-cell transmittance of less than 41% and satisfies equation (1): ΔTs(%)=Ts 96 -Ts0 represents the condition where the change in monomer transmittance (ΔTs) is 0% or more and 5% or less. This polarizing film has a high iodine content in its polarizing film, resulting in an initial monomer transmittance of less than 41%. Furthermore, it exhibits excellent performance in suppressing the decrease in monomer transmittance caused by coloration of the polarizing film in high-temperature environments, and consequently, excellent performance in suppressing the decrease in polarization degree in high-temperature and high-humidity environments (humidification durability).

Description

Technical Field

[0001] This invention relates to polarizing films. Background Technology

[0002] Conventionally, polarizing films used in various image display devices such as liquid crystal displays and organic EL displays have employed dyed polyvinyl alcohol (PVA) films (containing dichroic substances such as iodine and dichroic dyes) to achieve both high transmittance and high polarization. These polarizing films are manufactured by subjecting the PVA film to various treatments in a bath, such as swelling, dyeing, crosslinking, and stretching, followed by cleaning and drying. Furthermore, these polarizing films are typically used in the form of polarizing films (polarizers) with a protective film such as cellulose triacetate bonded to one or both sides using an adhesive.

[0003] On the other hand, with the thinning of polarizing films, there is a demand for polarizing films with a high iodine content (Patent Document 1). Furthermore, among such thin polarizing films, there are also known polarizing films that can suppress the change in monomer transmittance in high-temperature environments (105°C × 30 hours) (Patent Document 2).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2018 / 186244

[0007] Patent Document 2: International Publication No. 2019 / 103002 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] However, the thin polarizing film specifically disclosed in Patent Documents 1 and 2 does not adequately suppress the decrease in monomer transmittance in high-temperature environments, and there is room for improvement in this performance.

[0010] On the other hand, the inventors discovered that iodine contained in iodine-based polarizing films promotes polyene formation in high-temperature environments. Therefore, reducing the iodine content in the polarizing film is effective in suppressing the decrease in monomer transmittance caused by coloration of the polarizing film in high-temperature environments. However, it is difficult to obtain polarizing films with good polarization and high iodine content.

[0011] Furthermore, as described in Patent Document 2, in polarizing films with a high iodine content, from the viewpoint of improving contrast by setting a lower monomer transmittance, a polarizing film with a monomer transmittance of 41% or less is required.

[0012] In addition, polarizing films have the following problems in high temperature and high humidity environments: the boric acid crosslinking in the polarizing film is unlinked, and the iodine complex is destroyed, which leads to a decrease in polarization degree.

[0013] In view of the above, the object of the present invention is to provide a polarizing film with a high iodine content in the polarizing film, an initial monomer transmittance of less than 41%, excellent effect in suppressing the decrease in monomer transmittance caused by the coloration of the polarizing film in high temperature environment, and excellent effect in suppressing the decrease in polarization degree in high temperature and high humidity environment (humidification durability).

[0014] Problem Solving Methods

[0015] Specifically, the present invention relates to a polarizing film, which is a polarizing film on at least one side of a polarizing film having a transparent protective film or an optical functional film bonded thereto. The polarizing film is formed by adsorbing iodine onto a polyvinyl alcohol film and orienting it, and the iodine concentration exceeds 10% by weight. The transparent protective film or the optical functional film has a moisture permeability of 200 g / (m²). 2 The first film (within 24 hours) has a single-cell transmittance of less than 41% and satisfies equation (1): ΔTs(%)=Ts 96 -Ts0 (in the above formula (1), Ts0 is the single-unit transmittance of the laminate in which a glass plate is bonded to the opposite side of the first film surface of the polarizing film via an adhesive layer, Ts 96 The value represents the monomer transmittance after the above-mentioned laminate has been heated at 105°C for 96 hours. The value represents the condition where the change in monomer transmittance (ΔTs) is 0% or more and 5% or less.

[0016] The effects of the invention

[0017] The exact mechanism of action of the polarizing film of the present invention is not fully understood, but it is presumed to be so. However, the present invention may be interpreted in a way that is not limited to this mechanism.

[0018] The polarizing film of the present invention is a polarizing film on at least one side of a polarizing film having a transparent protective film or an optical functional film bonded thereto. The polarizing film is formed by adsorbing iodine onto a polyvinyl alcohol film and orienting it, and the iodine concentration exceeds 10% by weight. The transparent protective film or the optical functional film has a moisture permeability of 200 g / (m²). 2 The first film (within 24 hours) has a single-cell transmittance of less than 41% and satisfies equation (1): ΔTs(%)=Ts 96 -Ts0 (in the above formula (1), Ts0 is the single-unit transmittance of the laminate in which a glass plate is bonded to the opposite side of the first film surface of the polarizing film via an adhesive layer, Ts 96The term "transmittance" indicates the monomer transmittance after the above-mentioned laminate has been heated at 105°C for 96 hours. The change in monomer transmittance (ΔTs) is 0% or more and 5% or less. For the polarizing film of the present invention, since the change in monomer transmittance (ΔTs) after the above-mentioned heat treatment (in a high-temperature environment) is small, the decrease in monomer transmittance caused by the coloring of the polarizing film can be suppressed. The reason why the change in monomer transmittance (ΔTs) before and after the heat treatment can be presumed to be small is that the temperature at which the dehydration reaction caused by polyene formation occurs in the polarizing film of the present invention is higher than that of conventional polarizing films. In particular, the above-mentioned heat treatment is a heat durability test, which serves as an indicator of the heat resistance of the display, and is more stringent than the heat durability tests in Patent Documents 1 and 2. Furthermore, for the polarizing film of the present invention, by setting the iodine concentration in the polarizing film to a certain range, the temperature at which the dehydration reaction caused by polyene formation occurs can be controlled to a high-temperature side, and the initial polarization degree becomes good.

[0019] Furthermore, regarding the polarizing film of the present invention, since the moisture transmittance of the aforementioned transparent protective film or the aforementioned optical functional film is 200 g / (m²), 2 • · 24h or less, therefore, by preventing water from entering the polarizing film, the effect of suppressing the reduction of polarization degree (humidification durability) is excellent even in high temperature and high humidity environments. Detailed Implementation

[0020] <Polarizing film>

[0021] The polarizing film of the present invention is an iodine-based polarizing film formed by adsorbing iodine onto a polyvinyl alcohol film and orienting it, and the iodine content exceeds 10% by weight.

[0022] From the viewpoint of ensuring good initial polarization of the polarizing film, the iodine content of the aforementioned polarizing film exceeds 10% by weight. From the viewpoint of controlling the initial polarization to be 99.98% or higher, the iodine content of the aforementioned polarizing film is preferably 12% by weight or more, more preferably 15% by weight or more. Furthermore, from the viewpoint of ensuring that the temperature at which the dehydration reaction caused by polyene formation occurs is high, the iodine content is preferably 30% by weight or less, more preferably 25% by weight or less.

[0023] From the viewpoint of controlling the initial polarization degree to 99.98% or more, the thickness of the polarizing film is preferably 0.2 μm or more, more preferably 0.5 μm or more. Furthermore, from the viewpoint of thinning the polarizing film, the thickness is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less.

[0024] The aforementioned polarizing film preferably contains a free radical scavenger. It is presumed that this scavenger can capture free radicals generated by heating the polyvinyl alcohol in the polarizing film, thus setting the temperature of the polyene-reducing dehydration reaction to a high-temperature side. Examples of such free radical scavengers include hindered phenols, hindered amines, phosphorus compounds, sulfur compounds, benzotriazoles, benzophenones, hydroxylamines, salicylates, and triazine compounds. From the viewpoint that the temperature of the polyene-reducing dehydration reaction can be easily set to a high-temperature side, compounds having nitrocellulose radicals or nitrocellulose groups are preferred as such free radical scavengers.

[0025] As for the compounds containing nitryl radicals or nitryl groups mentioned above, from the viewpoint of having relatively stable free radicals at room temperature and in air, N-hydroxyl radical compounds (containing CN(-C)-O) can be cited as examples. · Compounds with functional groups (O) · (This refers to oxygen free radicals) and known compounds can be used. Examples of N-hydroxyl radical compounds include compounds with organic groups having the following structures.

[0026] [Chemical Formula 1]

[0027]

[0028] (In equation (1), R) 1 R represents oxygen free radicals. 2 ~R 5 The number of hydrogen atoms or alkyl groups with 1 to 10 carbon atoms can be independently represented (n represents 0 or 1). It should be noted that the left side of the dashed part in formula (1) represents any organic group.

[0029] Examples of compounds having the above-mentioned organic groups include compounds represented by the following general formulas (2) to (5).

[0030] [Chemical Formula 2]

[0031]

[0032] (In general formula (2), R) 1 ~R 5 And n has the same meaning as above, R 6 (This indicates a hydrogen atom, an alkyl group, an acyl group, or an aryl group with 1 to 10 carbon atoms; n represents 0 or 1.)

[0033] [Chemical Formula 3]

[0034]

[0035] (In general formula (3), R) 1 ~R 5And n has the same meaning as above, R 7 and R 8 (Independently representing a hydrogen atom, an alkyl group, an acyl group, or an aryl group having 1 to 10 carbon atoms.)

[0036] [Chemical Formula 4]

[0037]

[0038] (In general formula (4), R) 1 ~R 5 And n has the same meaning as above, R 9 ~R 11 Independently representing a hydrogen atom, an alkyl group, acyl group, amino group, alkoxy group, hydroxyl group, or aryl group having 1 to 10 carbon atoms.

[0039] [Chemical Formula 5]

[0040]

[0041] (In general formula (5), R) 1 ~R 5 And n has the same meaning as above, R 12 (This refers to a hydrogen atom, or an alkyl, amino, alkoxy, hydroxyl, or aryl group having 1 to 10 carbon atoms.)

[0042] From the perspective of ease of acquisition, in equations (1) to (5) above, R 2 ~R 5 Preferably, it is an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. Furthermore, in the above general formula (2), from the viewpoint of ease of acquisition, R... 6 Preferably, it is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom. Furthermore, in the above general formula (3), from the viewpoint of ease of acquisition, R... 7 and R 8 Preferably, it is an alkyl group that is independently composed of hydrogen atoms or has 1 to 10 carbon atoms, and more preferably, it is composed of hydrogen atoms. Furthermore, in the above general formula (4), from the viewpoint of ease of acquisition, R... 9 ~R 11 Preferably, it is an alkyl group having 1 to 10 hydrogen atoms. Furthermore, in the above general formula (5), from the viewpoint of ease of acquisition, R... 12 Preferably, it is hydroxyl, amino, or alkoxy. In the above formulas (1) to (5), from the viewpoint of ease of acquisition, n is preferably 1.

[0043] In addition, examples of the aforementioned N-hydroxyl compounds include those described in Japanese Patent Application Publication No. 2003-64022, Japanese Patent Application Publication No. 11-222462, Japanese Patent Application Publication No. 2002-284737, and International Publication No. 2016 / 047655.

[0044] Furthermore, from the viewpoint of being able to efficiently capture free radicals generated in the polyolefination reaction, the molecular weight of the aforementioned free radical scavenger is preferably 1000 or less, more preferably 500 or less, and even more preferably 300 or less.

[0045] From the viewpoint that it can be efficiently infiltrated into the polarizing film along with water during the manufacturing process, from the viewpoint that it can be impregnated into the polarizing film at a high concentration, and from the viewpoint that it can be impregnated in a short time even when using a thick polyvinyl alcohol film, thereby improving the productivity of the polarizing film, the above-mentioned free radical scavenger is preferably soluble in 1 part by weight or more in 100 parts by weight of water at 25°C, more preferably soluble in 2 parts by weight or more in 100 parts by weight of water at 25°C, and even more preferably soluble in 5 parts by weight or more in 100 parts by weight of water at 25°C.

[0046] In addition, the following compounds can be cited as examples of compounds having nitrocellulose radicals or nitrocellulose groups.

[0047] [Chemical Formula 6]

[0048]

[0049] (In general formula (6), R represents a hydrogen atom, an alkyl group, an acyl group, or an aryl group with 1 to 10 carbon atoms.)

[0050] [Chemical Formula 7]

[0051]

[0052] [Chemical Formula 8]

[0053]

[0054] When the polarizing film contains the free radical scavenger, from the viewpoint of suppressing the decrease in monomer transmittance caused by the coloring of the polarizing film in a high-temperature environment, the content of the free radical scavenger in the polarizing film is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, and even more preferably 0.5% by weight or more. In addition, from the viewpoint of appearance, it is preferably 30% by weight or less, more preferably 20% by weight or less, and even more preferably 10% by weight or less.

[0055] Furthermore, when the polarizing film contains the free radical scavenger, from the viewpoint of suppressing the decrease in monomer transmittance caused by the coloring of the polarizing film in a high-temperature environment, the weight ratio of the content of the free radical scavenger to the content of iodine in the polarizing film (weight ratio of free radical scavenger content / weight ratio of iodine content) is preferably 0.01 or more, more preferably 0.05 or more. In addition, from the viewpoint of appearance, it is preferably 1.0 or less, more preferably 0.5 or less.

[0056] <Manufacturing Method of Polarizing Film>

[0057] The method for manufacturing the aforementioned polarizing film includes: performing an optional swelling step, a cleaning step, and a drying step on a polyvinyl alcohol (PVA) film, and at least performing a dyeing step, a crosslinking step, and a stretching step to obtain the aforementioned polarizing film. The iodine content in the aforementioned polarizing film can be controlled by the concentration of the aforementioned iodine and iodides such as potassium iodide in any of the processing baths in the swelling step, dyeing step, crosslinking step, stretching step, and cleaning step, as well as the processing temperature and processing time in each of the aforementioned processing baths. Furthermore, each step can be performed in any suitable order, and a single step can be performed multiple times as needed.

[0058] The aforementioned polyvinyl alcohol (PVA) films can be used without particular limitation. These films are transparent in the visible light region and are obtained by dispersing and adsorbing dichroic substances such as iodine and dichroic dyes. Examples of materials for the aforementioned PVA films include polyvinyl alcohol or its derivatives. Examples of PVA derivatives include: polyvinyl formal, polyvinyl acetal; olefins such as ethylene and propylene; and derivatives obtained by modifying unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, their alkyl esters, and acrylamide. The average degree of polymerization of the aforementioned PVA is preferably about 100 to 10,000, more preferably about 1,000 to 10,000, and even more preferably about 1,500 to 4,500. Furthermore, the degree of saponification of the aforementioned PVA is preferably about 80 to 100 mol%, more preferably about 95 mol% to 99.95 mol%. It should be noted that the aforementioned average degree of polymerization and degree of saponification can be determined based on JIS K 6726.

[0059] Plasticizers, surfactants, and other additives can be included in the aforementioned polyvinyl alcohol (PVA) films. Examples of plasticizers include glycerol, diglycerol, triglyceride, ethylene glycol, propylene glycol, polyethylene glycol, and other polyols and their condensates. There are no particular limitations on the amount of these additives used; for example, approximately 20% by weight or less is suitable in PVA films.

[0060] The aforementioned polyvinyl alcohol (PVA) film can be obtained by forming a polyvinyl alcohol (PVA) resin layer on one side of a strip-shaped thermoplastic resin substrate. As a method for producing the aforementioned laminate, any suitable method can be used; for example, a method of coating the surface of the aforementioned thermoplastic resin substrate with a coating liquid containing the aforementioned PVA resin and then drying it. The thickness of the aforementioned thermoplastic resin substrate is preferably about 20 to 300 μm, more preferably about 50 to 200 μm. The thickness of the aforementioned PVA resin layer is preferably about 3 to 40 μm, more preferably about 3 to 20 μm.

[0061] As a constituent material of the aforementioned thermoplastic resin substrate, any suitable thermoplastic resin can be used. Examples of such thermoplastic resins include: ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene resins, polyamide resins, polycarbonate resins, and copolymers thereof. Among these, norbornene resins and amorphous (non-crystalline) polyethylene terephthalate resins are preferred. Furthermore, from the viewpoint that the thermoplastic resin substrate has excellent tensile properties and that crystallization during stretching can be suppressed, amorphous (non-crystalline) polyethylene terephthalate resins are preferred. Examples of amorphous (non-crystalline) polyethylene terephthalate resins include copolymers containing isophthalic acid and / or cyclohexanedicarboxylic acid as dicarboxylic acids, and copolymers containing cyclohexanediol and diethylene glycol as diols.

[0062] Before forming the PVA-type resin layer, the thermoplastic resin substrate can be surface-treated (e.g., corona treatment), or an easy-to-adhere layer can be formed on the thermoplastic resin substrate. Such treatments improve the adhesion between the thermoplastic resin substrate and the PVA-type resin layer. Alternatively, the thermoplastic resin substrate can be stretched before forming the PVA-type resin layer.

[0063] The coating solution described above is a solution obtained by dissolving PVA-based resin in a solvent. Examples of such solvents include: water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyols such as trimethylolpropane, amines such as ethylenediamine and diethylenetriamine, with water being 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 closely to the thermoplastic resin substrate, the concentration of PVA-based resin in the coating solution is preferably about 3 to 20 parts by weight relative to 100 parts by weight of the solvent.

[0064] From the viewpoint of improving the orientation of polyvinyl alcohol molecules based on stretching, a halide can be incorporated into the coating solution. Any suitable halide can be used as the halide, such as iodides and sodium chloride. Examples of iodides include potassium iodide, sodium iodide, and lithium iodide, with potassium iodide being preferred. The concentration of the halide in the coating solution is preferably about 5 to 20 parts by weight, more preferably about 10 to 15 parts by weight, relative to 100 parts by weight of PVA resin.

[0065] In addition, additives can be incorporated into the coating liquid. Examples of such additives include plasticizers such as ethylene glycol and glycerin, and surfactants such as nonionic surfactants.

[0066] As a coating method for the above-mentioned coating liquid, any appropriate method can be adopted, such as: roller coating, spin coating, bar coating, dip coating, mold coating, curtain coating, spraying, and scraping coating (comma coating, etc.).

[0067] In the above stretching process, PVA films are typically stretched unidirectionally to approximately 3 to 7 times their original length. The stretching direction can be either the length direction (MD direction) or the width direction (TD direction). From the viewpoint of laminating transparent protective films or optical functional films in a roll-to-roll manner, the stretching direction is preferably the TD direction. The stretching method can be dry stretching, wet stretching, or a combination thereof. Additionally, PVA films can be stretched during crosslinking, swelling, dyeing, etc. The stretching process can be performed in one stage or in multiple stages. In the case of multiple stages, the stretching ratio is the product of the stretching ratios of each stage. It should be noted that the stretching direction can correspond to the absorption axis direction of the resulting polarizing film.

[0068] As needed, the swelling process described above is performed before the dyeing process. The swelling process is performed, for example, by immersing a PVA film in a swelling bath. Water, such as distilled water or pure water, is typically used as the swelling bath. The swelling bath may contain any suitable components other than water. Examples of such other components include solvents such as alcohols, additives such as surfactants, and iodides. Examples of such iodides include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide, with potassium iodide being preferred. The temperature of the swelling bath is, for example, around 20–45°C. The immersion time is, for example, around 10–300 seconds.

[0069] The above-described dyeing process involves dyeing a PVA membrane with a dichroic substance. Examples of adsorption methods include: immersing the PVA membrane in a dyeing solution containing the dichroic substance; coating the PVA membrane with the dyeing solution; and spraying the dyeing solution onto the PVA membrane. From the viewpoint of effectively adsorbing the dichroic substance, immersing the PVA membrane in the dyeing solution is preferred.

[0070] Examples of dichroic substances include iodine and dichroic dyes, with iodine being preferred. When using iodine as the dichroic substance, an aqueous iodine solution is preferred as the dyeing solution. The iodine content in the aqueous iodine solution is preferably about 0.04 to 5.0 parts by weight relative to 100 parts by weight of water. Furthermore, to improve the solubility of iodine in water, it is preferable to incorporate an iodide into the aqueous iodine solution. Potassium iodide is preferred as the iodide. The iodide content is preferably about 0.3 to 15 parts by weight relative to 100 parts by weight of water. From the viewpoint of obtaining a polarizing film with good optical properties, the ratio of iodine to iodide content in the aqueous iodine solution is preferably about 1:5 to 1:20, more preferably about 1:5 to 1:10. The temperature of the dyeing solution is, for example, 20 to 50°C. The immersion time is, for example, 5 seconds to 5 minutes.

[0071] In the above-described crosslinking process, a boron compound is typically used as a crosslinking agent. Examples of such boron compounds include boric acid and borax, with boric acid being preferred. The boron compound is usually used in the form of an aqueous solution. In the aqueous solution containing the boron compound, the concentration of the boron compound is, for example, about 0.5 to 15% by weight, preferably about 1 to 10% by weight. Furthermore, the aqueous solution containing the boron compound may contain iodides such as potassium iodide.

[0072] Examples of the crosslinking process described above include: impregnating a PVA membrane in an aqueous solution containing a boron compound; coating a PVA membrane with an aqueous solution containing a boron compound; spraying an aqueous solution containing a boron compound onto a PVA membrane, etc., with the impregnation method in an aqueous solution containing a boron compound being preferred.

[0073] In the above crosslinking process, the temperature of the aqueous solution containing the boron compound is, for example, 25°C or higher, preferably around 30–85°C, and more preferably around 40–70°C. The immersion time is, for example, around 5–800 seconds, preferably around 8–500 seconds.

[0074] As needed, the above cleaning process is performed after the crosslinking process. The cleaning process is typically performed by immersing the PVA membrane in a cleaning solution. A representative example of a cleaning solution is pure water. Iodides such as potassium iodide may be included in the cleaning solution. The temperature of the cleaning solution is, for example, approximately 5–50°C. The immersion time is, for example, approximately 1–300 seconds.

[0075] Furthermore, when manufacturing a polarizing film containing the aforementioned free radical scavenger, the free radical scavenger may be present in any one or more of the processing baths in the swelling step, the cleaning step, the dyeing step, the crosslinking step, and the stretching step. The concentration of the free radical scavenger in any of the aforementioned processing baths is affected by the number of treatments, processing time, and processing temperature, and therefore cannot be determined uniformly. From the viewpoint of efficiently controlling the content of the free radical scavenger in the polarizing film, it is generally preferred to be 0.01% by weight or more, more preferably 0.05% by weight or more, further preferably 0.1% by weight or more, and preferably 30% by weight or less, more preferably 25% by weight or less, and further preferably 20% by weight or less.

[0076] Furthermore, additives such as zinc salts, pH adjusters, pH buffers, and other salts may be included in the treatment baths of the aforementioned swelling, dyeing, cross-linking, stretching, and cleaning processes. Examples of zinc salts include zinc halides such as zinc chloride and zinc iodide; and inorganic zinc salts such as zinc sulfate and zinc acetate. Examples of pH adjusters include strong acids such as hydrochloric acid, sulfuric acid, and nitric acid; and strong bases such as sodium hydroxide and potassium hydroxide. Examples of pH buffers include carboxylic acids such as acetic acid, oxalic acid, and citric acid, and their salts; and inorganic weak acids such as phosphoric acid and carbonic acid, and their salts. Examples of other salts include 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.

[0077] Examples of the aforementioned drying processes include natural drying, forced-air drying, reduced-pressure drying, and heat drying, with heat drying being preferred. In the case of heat drying, the heating temperature is, for example, 30–100°C. Furthermore, the drying time is, for example, 20 seconds to 10 minutes.

[0078] <Polarizing film>

[0079] The polarizing film of the present invention is a polarizing film on at least one side of the aforementioned polarizing film having a transparent protective film or an optical functional film bonded thereto, wherein the transparent protective film or the aforementioned optical functional film has a moisture transmittance of 200 g / (m²). 2 The first film (within 24 hours) has a single-cell transmittance of less than 41% and satisfies equation (1): ΔTs(%)=Ts 96 -Ts0 (in the above formula (1), Ts0 is the single-unit transmittance of the laminate in which a glass plate is bonded to the opposite side of the first film surface of the polarizing film via an adhesive layer, Ts 96The value represents the monomer transmittance after the above-mentioned laminate has been heated at 105°C for 96 hours. The value represents the condition where the change in monomer transmittance (ΔTs) is 0% or more and 5% or less.

[0080] There are no particular limitations on the aforementioned transparent protective film, and various transparent protective films used in polarizing films can be used. As materials constituting the aforementioned transparent protective film, thermoplastic resins with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy can be used, for example. Examples of such thermoplastic resins include: cellulose ester resins such as cellulose triacetate, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone resins, polysulfone resins, polycarbonate resins, nylon, polyamide resins such as aromatic polyamides, polyimide resins, polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers, (meth)acrylic resins, cyclic or cyclic polyolefin resins with a norbornene structure (norbornene resins), polyaryl ester resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. Furthermore, the aforementioned transparent protective film can be a cured layer formed from thermosetting resins such as (meth)acrylic acid, urethane, acrylate urethane, epoxy, and silicone, or ultraviolet-curable resins. Among these, cellulose ester resins, polycarbonate resins, (meth)acrylic resins, cyclic polyolefin resins, and polyester resins are preferred.

[0081] The thickness of the aforementioned transparent protective film can be appropriately determined. Generally speaking, from the perspectives of strength, processability, operability, and thinness, it is preferably about 1 to 500 μm, more preferably about 1 to 300 μm, and even more preferably about 5 to 100 μm.

[0082] The aforementioned transparent protective film may contain any suitable additives such as UV absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, antistatic agents, pigments, and colorants. In particular, the inclusion of UV absorbers in the aforementioned transparent protective film can improve the lightfastness of the polarizing film.

[0083] The aforementioned optical functional film is not particularly limited. For example, optical functional films sometimes used in the formation of liquid crystal display devices, such as one or more layers of reflective plates, semi-transparent plates, phase retardation plates (including 1 / 2 and 1 / 4 wave plates), viewing angle compensation films, linear polarization separation films, and other brightness-enhancing films, can be used. Examples of polarizing films having the aforementioned optical functional film include: a reflective polarizing film or a semi-transparent polarizing film formed by further stacking a reflective plate or a semi-transparent reflective plate on the aforementioned polarizing film; an elliptical polarizing film or a circular polarizing film formed by further stacking a phase retardation plate on the aforementioned polarizing film; a wide-viewing-angle polarizing film formed by further stacking a viewing angle compensation film on the aforementioned polarizing film; or a polarizing film formed by further stacking a brightness-enhancing film on the aforementioned polarizing film.

[0084] The moisture transmittance of the transparent protective film or the optical functional film (the first film on one side of the polarizing film) adhered to at least one side of the polarizing film is 200 g / (m²). 2 From the perspective of suppressing the decrease in polarization degree of the polarizing film in high temperature and high humidity environments (24h and below), the preferred humidity transmittance is 180 g / (m²). 2 • 24h or less, more preferably 150g / (m 2 • 24h or less. Furthermore, from the viewpoint of production efficiency in the drying process after laminating the polarizing film with the transparent protective film or optical functional film, the moisture permeability of the other transparent protective film or optical functional film (the second film on the other side of the polarizing film) is preferably 200 g / (m²). 2 • 24h or more, more preferably 300g / (m 2 Furthermore, from the viewpoint of suppressing the decrease in polarization degree of the polarizing film in high temperature and high humidity environments, the transmittance is preferably 1200 g / (m²). 2 • 24h or less, more preferably 1000g / (m 2 • 24h or less. It should be noted that the permeability can be calculated as follows: According to the permeability test (cup method) of JIS Z0208, the sample cut into 60mm diameter pieces is placed in a permeability cup containing about 15g of calcium chloride, and placed in a constant temperature machine at 40℃ and 90%RH. The weight increase of calcium chloride before and after 24 hours is measured.

[0085] When the above-mentioned transparent protective film or optical functional film is attached to both sides of the above-mentioned polarizing film, the films on the two sides may be the same or different.

[0086] Functional layers such as a hard coating layer, anti-reflective layer, anti-adhesion layer, diffusion layer, and anti-glare layer can be provided on the side of the aforementioned transparent protective film or optical functional film that is not attached to the polarizing film. It should be noted that the aforementioned functional layers such as the hard coating layer, anti-reflective layer, anti-adhesion layer, diffusion layer, and anti-glare layer can be provided as the film itself, or they can be separately provided as layers different from the film.

[0087] The polarizing film and the transparent protective film or the optical functional film, or the polarizing film and the functional layer, are usually bonded together with an adhesive layer or bonding agent layer in between.

[0088] As the adhesive for forming the adhesive layer described above, various adhesives used in polarizing films can be applied, such as: rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, cellulose adhesives, etc. Among these, acrylic adhesives are preferred.

[0089] Examples of methods for forming the adhesive layer include: applying the adhesive to a diaphragm or similar material that has undergone a peeling treatment and drying it to form an adhesive layer, and then transferring it to a polarizing film or similar material; or applying the adhesive to a polarizing film or similar material and drying it to form an adhesive layer. The thickness of the adhesive layer is not particularly limited, but is, for example, about 1 to 100 μm, preferably about 2 to 50 μm.

[0090] As the adhesive used to form the adhesive layer described above, various adhesives applicable to polarizing films can be used, such as isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex adhesives, and waterborne polyester adhesives. These adhesives are typically used in the form of adhesives formed from aqueous solutions (waterborne adhesives) and contain 0.5 to 60% by weight of solid components.

[0091] The aforementioned water-based adhesive may contain a crosslinking agent. As the crosslinking agent, a compound typically used is one having at least two functional groups in one molecule that are reactive with the polymer or other components constituting the adhesive. Examples include: alkylene diamines; isocyanates; epoxy compounds; aldehydes; amino-formaldehydes such as hydroxymethylurea and hydroxymethyl melamine. The amount of crosslinking agent in the adhesive is typically about 10 to 60 parts by weight relative to 100 parts by weight of the polymer or other components constituting the adhesive.

[0092] In addition to the above, examples of adhesives that can be cured by active energy radiation, such as ultraviolet-cured adhesives and electron beam-cured adhesives, are also examples of adhesives that can be cured by active energy radiation. Examples of such active energy radiation-cured adhesives include (meth)acrylate adhesives. Examples of curing components in such (meth)acrylate adhesives include compounds having (meth)acryloyl groups and compounds having vinyl groups. Examples of compounds having (meth)acryloyl groups include alkyl esters of (meth)acrylate with 1 to 20 carbon atoms, cycloalkyl esters of (meth)acrylate, polycyclic alkyl esters of (meth)acrylate, and other alkyl esters of (meth)acrylate; hydroxyl-containing (meth)acrylates; glycidyl esters of (meth)acrylate, and epoxy-containing (meth)acrylates, etc. (Meth)acrylate adhesives may contain nitrogen-containing monomers such as hydroxyethyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, (meth)acrylamide, and (meth)acryloylmorpholine. (Meth)acrylate adhesives may also contain tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecanediethanol diacrylate, cyclic trimethylolpropane methyl acetal acrylate, and di... Multifunctional monomers such as alkyl glycol diacrylate and EO-modified diglycerol tetraacrylate are used as crosslinking components. Additionally, compounds with epoxy groups or oxocyclic butyl groups can also be used as cationic polymerization curing adhesives. There are no particular limitations on compounds with epoxy groups, as long as they have at least two epoxy groups within the molecule; various commonly known curing epoxy compounds can be used.

[0093] The aforementioned adhesives may also contain suitable additives as needed. Examples of such additives include: silane coupling agents, titanium coupling agents, and other coupling agents; ethylene oxide and other adhesion promoters; ultraviolet absorbers; deterioration inhibitors; dyes; processing aids; ion scavengers; antioxidants; tackifiers; fillers; plasticizers; leveling agents; foaming inhibitors; antistatic agents; heat stabilizers; and hydrolysis stabilizers.

[0094] The adhesive coating can be applied to any one of the following sides: the transparent protective film or the optical functional film (or the functional layer side), or the polarizing film side; or it can be applied to both sides. After bonding, a drying process is performed to form an adhesive layer made of the coated and dried layer. After the drying process, ultraviolet light or an electron beam can be applied as needed. The thickness of the adhesive layer is not particularly limited. When using water-based adhesives, it is preferably about 30 to 5000 nm, more preferably about 100 to 1000 nm. When using ultraviolet-curing adhesives or electron beam-curing adhesives, it is preferably about 0.1 to 100 μm, more preferably about 0.5 to 10 μm.

[0095] The aforementioned transparent protective film or optical functional film and the aforementioned polarizing film, or the aforementioned polarizing film and the aforementioned functional layer, can be stacked together with interlayers such as surface modification treatment layer, easy-to-adhere layer, blocking layer, and refractive index adjustment layer.

[0096] Examples of surface modification treatments for forming the above-mentioned surface modified layer include: corona treatment, plasma treatment, primer treatment, saponification treatment, etc.

[0097] Examples of easy-adhesive agents used to form the aforementioned easy-adhesive layer include: resins comprising various resins having a polyester backbone, polyether backbone, polycarbonate backbone, polyurethane backbone, silicone backbone, polyamide backbone, polyimide backbone, polyvinyl alcohol backbone, etc. The aforementioned easy-adhesive layer can typically be pre-formed on the aforementioned film, and the easy-adhesive layer side of the film is laminated to the polarizing film via the aforementioned adhesive layer or adhesive layer.

[0098] The aforementioned barrier layer is a layer that serves to prevent impurities such as oligomers and ions dissolved from the aforementioned transparent protective film or optical functional film from migrating (invading) into the polarizing film. The barrier layer can be any layer that is transparent and can prevent impurities dissolved from the aforementioned transparent protective film or optical functional film. Examples of materials forming the barrier layer include: urethane prepolymer forming materials, cyanoacrylate forming materials, epoxy forming materials, etc.

[0099] The aforementioned refractive index adjustment layer is provided to suppress the decrease in transmittance caused by reflections between layers with different refractive indices, such as the aforementioned transparent protective film or the aforementioned optical functional film and polarizing film. Examples of refractive index adjustment materials forming the aforementioned refractive index adjustment layer include forming materials comprising various resins and additives such as silica-based, acrylic-based, acrylic-styrene-based, and melamine-based resins.

[0100] The polarizing film of the present invention satisfies equation (1): ΔTs(%)=Ts 96 -Ts0 (in the above formula (1), Ts0 is the single-unit transmittance of the laminate in which a glass plate is bonded to the opposite side of the first film surface of the polarizing film via an adhesive layer, Ts 96 The term "transmittance" indicates the monomer transmittance after heat treatment at 105°C for 96 hours. The change in monomer transmittance (ΔTs) is 0% or more and 5% or less. It should be noted that the change in monomer transmittance (ΔTs) is preferably 0% or more and 3% or less.

[0101] The transmittance of the aforementioned polarizing film is 41% or less. From the viewpoint of display panel brightness, the transmittance of the aforementioned polarizing film is preferably 30% or more, more preferably 35% or more. Furthermore, from the viewpoint of controlling the initial degree of polarization to 99.98% or more, the transmittance is preferably 41% or less, more preferably 40% or less. It should be noted that the transmittance is a Y value obtained by measuring using a spectrophotometer with an integrating sphere (e.g., manufactured by Nippon Spectrophotometer Co., Ltd., product name: V7100) with a 2-degree field of view (C-light source) of JIS Z8701 and performing visibility correction.

[0102] The polarization degree of the above-mentioned polarizing film is preferably 99.98% or higher, and more preferably 99.99% or higher.

[0103] An adhesive layer for bonding other components can be provided on one or both sides of the aforementioned polarizing film. Preferably, an adhesive layer is used as this adhesive layer. There are no particular limitations on the adhesive used to form this adhesive layer; adhesives with polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorinated polymers, and rubbers as the base polymer can be suitably selected. Adhesives containing acrylic polymers, exhibiting excellent optical transparency, moderate wetting, cohesiveness, and adhesion, as well as excellent weather resistance and heat resistance, are particularly preferred.

[0104] The adhesive layer can be applied to one or both sides of the polarizing film in a suitable manner. Examples of applying the adhesive layer include: preparing an adhesive solution and directly applying it to the polarizing film using a suitable spreading method such as casting or coating; or forming an adhesive layer on a separator and transferring it to the polarizing film. The thickness of the adhesive layer can be appropriately determined according to the intended use, adhesion strength, etc., and is generally 1–500 μm, preferably 5–200 μm, and more preferably 10–100 μm. Materials in which an adhesive layer is thus applied to at least one side of the polarizing film are also referred to as polarizing films with an adhesive layer.

[0105] For the purpose of preventing contamination, the exposed surface of the adhesive layer is preferably temporarily covered by an adhesive diaphragm until it is put into actual use. This prevents contamination of the adhesive layer under normal handling conditions. As the diaphragm, a suitable thin film such as plastic film, rubber sheet, paper, cloth, nonwoven fabric, mesh, foam sheet, metal foil, and their laminates can be used as needed, coated with suitable release agents such as silicone, long-chain alkyl, fluorine, or molybdenum sulfide.

[0106] Example

[0107] The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0108] <Example 1>

[0109] <Fabrication of Polarizing Films>

[0110] As the thermoplastic resin substrate, a 100 μm thick poly(ethylene terephthalate) (IPA) copolymer PET film was used. One side of the substrate was corona-treated, and an aqueous solution containing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetyl-modified PVA (degree of polymerization 1200, acetyl-modification rate 4.6%, degree of saponification ≥ 99.0 mol%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gohsefimer Z200") in a 9:1 ratio was coated onto the corona-treated surface at 25°C and dried to form a PVA-based resin layer, thus producing a laminate. The resulting laminate was stretched at 140°C in a gas atmosphere at 4.5 times its length (stretching treatment). Next, the laminate was stained for 12 seconds in a staining bath (an aqueous solution of 1.0 wt% iodine and 7.0 wt% potassium iodide) at 25°C. Then, it was stained for 21 seconds in a crosslinking bath (an aqueous solution of 1.0 wt% boron, 1.0 wt% potassium iodide, and 5.0 wt% of the compound represented by the following general formula (9)) at 60°C. Next, the laminate was stained for 10 seconds in a washing bath (an aqueous solution of 4.5 wt% potassium iodide) at 25°C. Finally, the laminate was dried in an oven at 60°C for 21 seconds to obtain a laminate with a PVA resin layer (polarizing film) of 1.2 μm thickness. Next, a linear polarization separator (manufactured by 3M, trade name "DBEF", moisture permeability 8.5 g / (m²)) was bonded to the polarization film side of the resulting laminate with a PVA resin layer (polarization film) through a 20 μm thick acrylic adhesive layer. 2 After 24 hours, the thermoplastic resin substrate was peeled off, and an acrylic adhesive layer with a thickness of 20 μm was applied to the peeled surface to produce a polarizing film with a monomer transmittance of 39.7%.

[0111] [Chemical Formula 9]

[0112]

[0113] [Method for determining the iodine content (wt%) in polarizing film]

[0114] For the polarizing film, the iodine concentration (wt%) was determined using a fluorescence X-ray analysis device (manufactured by Rigaku Corporation, trade name "ZSX-PRIMUSIV", measurement diameter: φ20mm) and the following formula.

[0115] Iodine concentration (wt%) = 14.474 × (fluorescent X-ray intensity) / (film thickness) (kcps / μm)

[0116] It should be noted that the coefficient used to calculate the concentration varies depending on the measuring device, and this coefficient can be obtained using an appropriate calibration curve. The results are shown in Table 1.

[0117] [Method for determining the dehydration temperature of polyenes]

[0118] The polarizing film was introduced into a furnace-type pyrolyzer (Frontier Lab, PY-2020iD), and the generated gas was directly introduced into a TOFMS (JEOL, MS-T100GCV) for determination based on generated gas analysis (EGA / TOFMS). The peak temperature of the maximum intensity of the detected water was then determined, and this temperature was set as the dehydration temperature for polyolefination.

[0119] [Measurement Conditions]

[0120] Heating conditions: 40℃ → +10℃ / min → 350℃

[0121] Interface: Deactivated fused silica tube, 2.5m × 0.15mm id

[0122] Carrier gas: He (1.0 mL / min)

[0123] Inlet temperature: 300℃

[0124] Note: Flow ratio 20:1

[0125] Interface temperature: 300℃

[0126] Mass spectrometer: TOFMS

[0127] Ionization method: EI method

[0128] Mass range: m / z = 18

[0129] [Method for determining the content (wt%) of free radical scavengers in polarizing films]

[0130] Approximately 20 mg of polarizing membrane was used for quantification. It was dissolved in 1 mL of water by heating, then diluted with 4.5 mL of methanol. The resulting extract was filtered through a membrane filter, and the concentration of the free radical scavenger was determined using HPLC (Waters ACQUITY UPLC H-class Bio). The results are shown in Table 1.

[0131] [Methods for measuring the degree of polarization]

[0132] The degree of polarization of a polarizing film can be measured using a spectrophotometer (Japanese Spectrophotometer, product name "V7100"). Specifically, the degree of polarization can be measured by determining the parallel transmittance (H0) and orthogonal transmittance (H90) of the polarizing film and calculating it using the formula: Degree of polarization (%) = {(H0 - H90) / (H0 + H90)}¹ / ² × 100. The parallel transmittance (H0) is the transmittance value of a parallel-type stacked polarizing film manufactured by stacking two identical polarizing films with their absorption axes parallel. Similarly, the orthogonal transmittance (H90) is the transmittance value of an orthogonal-type stacked polarizing film manufactured by stacking two identical polarizing films with their absorption axes orthogonal. It should be noted that these transmittance values ​​are Y values ​​obtained by correcting for visibility using a 2-degree field of view (C light source) according to JlS Z8701-1982. The results are shown in Table 1.

[0133] [Evaluation of monomer transmittance in high-temperature environments]

[0134] The polarizing film obtained above was cut into 5.0 × 4.5 cm pieces with the absorption axis parallel to the long side. A 1.3 mm alkali-free glass plate was then bonded to the adhesive layer of the polarizing film to create a laminate. The laminate was then placed in a hot air oven at 105 °C for 96 hours, and the single-cell transmittance (ΔTs) before and after heating was measured. The single-cell transmittance was measured using a spectrophotometer (Japanese Spectrophotometer, product name "V7100") and evaluated based on the following criteria. It should be noted that the measurement wavelength was 380–700 nm (in 5 nm intervals), and the results are shown in Table 1.

[0135] ΔTs(%)=Ts 96 -Ts0

[0136] Here, Ts0 is the monomer transmittance of the laminate before heating, and Ts 96 The transmittance of the laminate after heating for 96 hours is the monomer transmittance.

[0137] [Evaluation of Humidifier Durability]

[0138] The laminated samples were placed in a humid heat oven at 85°C and 85% RH for 120 hours. The polarization degree was then evaluated using the spectrophotometer (Japanese spectrophotometer, product name "V7100"). A polarization degree of 99% or higher after the test was taken as the pass standard. The results are shown in Table 1.

[0139] <Example 2>

[0140] In the above-described <Preparation of Polarizing and Polarizing Films>, the crosslinking bath was changed to a crosslinking bath (an aqueous solution with a boron concentration of 1.0 wt%, a potassium iodide concentration of 1.0 wt%, and a compound represented by the above general formula (9) at a concentration of 10.0 wt%). Otherwise, the polarizing and polarizing films were prepared by the same procedure as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0141] <Example 3>

[0142] In the above-described <Preparation of Polarizing and Polarizing Films>, the dyeing bath was changed to a dyeing bath (an aqueous solution of 0.7 wt% iodine and 4.9 wt% potassium iodide), and the crosslinking bath was changed to a crosslinking bath (an aqueous solution of 1.0 wt% boron, 1.0 wt% potassium iodide, and 10.0 wt% of the compound represented by the above general formula (9)). Otherwise, the polarizing and polarizing films were prepared by the same procedure as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0143] <Example 4>

[0144] In the above-described <Preparation of Polarizing and Polarizing Films>, the crosslinking bath was changed to a crosslinking bath (an aqueous solution with a boron concentration of 1.0 wt%, a potassium iodide concentration of 1.0 wt%, and a compound represented by the above general formula (8) at a concentration of 10.0 wt%). Otherwise, the polarizing and polarizing films were prepared by the same procedure as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0145] <Example 5>

[0146] In the above-described <Preparation of Polarizing and Polarizing Films>, the crosslinking bath was changed to a crosslinking bath (an aqueous solution with a boron concentration of 1.0 wt%, a potassium iodide concentration of 1.0 wt%, and a compound represented by the above general formula (7) at a concentration of 10.0 wt%). Otherwise, the polarizing and polarizing films were prepared by the same procedure as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0147] <Example 6>

[0148] In the aforementioned fabrication of polarizing film and polarizing film, a (meth)acrylic resin transparent protective film (manufactured by Nippon Shokubai Co., Ltd., with a moisture permeability of 125 g / (m²)) is laminated as the first film onto the polarizing film side of the laminate containing a PVA resin layer (polarizing film) through a 20 μm thick acrylic adhesive layer. 2 • 24h)) In addition, polarizing films and polarizing films were fabricated using the same procedures as in Example 1. The results of the above-described measurements and evaluations of the polarizing films and polarizing films are shown in Table 1.

[0149] <Example 7>

[0150] In the above-mentioned <Fabrication of Polarizing Film and Polarizing Film>, a linear polarizing separator (manufactured by 3M Corporation, trade name "DBEF", moisture permeability 85 g / (m²)) is attached to the polarizing film side of the obtained laminate with a PVA resin layer (polarizing film) as the first film, separated by an acrylic adhesive layer with a thickness of 20 μm. 2 • 24h)) Then, the thermoplastic resin substrate is peeled off, and a cellulose triacetate transparent protective film (manufactured by Fujifilm, trade name "TJ40UL", moisture permeability 380g / (m)) is laminated onto the peeled surface as the second film, through a 20μm thick acrylic adhesive layer. 2 After 24 hours, an acrylic adhesive layer with a thickness of 20 μm was coated on the side of the cellulose triacetate transparent protective film. Otherwise, a polarizing film and a polarizing film were fabricated using the same procedure as in Example 1. The results of the above-described measurements and evaluations of the polarizing film and the polarizing film are shown in Table 1.

[0151] <Example 8>

[0152] In the above-described fabrication of polarizing film and polarizing film, a PVA resin layer was formed to achieve a final polarizing film thickness of 4.8 μm, thereby fabricating a laminate. The dyeing bath was changed to a dyeing bath (an aqueous solution of 0.5 wt% iodine and 3.5 wt% potassium iodide), and the crosslinking bath was changed to a crosslinking bath (an aqueous solution of 1.0 wt% boron, 1.0 wt% potassium iodide, and a compound represented by the above general formula (9) at a concentration of 10.0 wt%). Otherwise, the polarizing film and polarizing film were fabricated using the same procedures as in Example 1. The results of the above-described measurements and evaluations of the polarizing film and polarizing film are shown in Table 1.

[0153] <Example 9>

[0154] In the above-described <Preparation of Polarizing and Polarizing Films>, the dyeing bath was changed to a dyeing bath (an aqueous solution of 1.5 wt% iodine and 10.5 wt% potassium iodide), and the crosslinking bath was changed to a crosslinking bath (an aqueous solution of 1.0 wt% boron, 1.0 wt% potassium iodide, and 15.0 wt% of the compound represented by the above general formula (9)). Otherwise, the polarizing and polarizing films were prepared by the same procedure as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0155] <Comparative Example 1>

[0156] In the above-described fabrication of polarizing and polarizing films, the crosslinking bath was changed to a crosslinking bath (an aqueous solution of 1.0 wt% boron and 1.0 wt% potassium iodide). Otherwise, the polarizing and polarizing films were fabricated using the same procedures as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0157] <Comparative Example 2>

[0158] In the aforementioned <Fabrication of Polarizing Film and Polarizing Film>, a triacetate cellulose resin transparent protective film (manufactured by Konica Minolta Co., Ltd., trade name "KC2CT", moisture permeability 380 g / (m²)) is bonded as the first film to the polarizing film side of the obtained laminate containing a PVA resin layer (polarizing film) through a 20 μm thick acrylic adhesive layer. 2 • 24h)) In addition, polarizing films and polarizing films were fabricated using the same procedures as in Example 1. The results of the above-described measurements and evaluations of the polarizing films and polarizing films are shown in Table 1.

[0159] <Comparative Example 3>

[0160] In the above-described <Preparation of Polarizing and Polarizing Films>, the dyeing bath was changed to a dyeing bath (an aqueous solution of 0.5% by weight iodine and 3.5% by weight potassium iodide), and the crosslinking bath was changed to a crosslinking bath (an aqueous solution of 1.0% by weight boron, 1.0% by weight potassium iodide, and 10.0% by weight of the compound represented by the above general formula (9)). Otherwise, the polarizing and polarizing films were prepared by the same procedure as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0161] <Comparative Example 4>

[0162] In the above-described fabrication of polarizing and polarizing films, a linear polarizing separator (manufactured by 3M, trade name "DBEF") serving as the first film was laminated to the polarizing film side of a laminate containing a PVA resin layer (polarizing film) with a 20 μm thick acrylic adhesive layer as a separator. The thermoplastic resin substrate was then peeled off, and a treatment solution (an aqueous solution of 0.5 wt% sodium bicarbonate and 50 wt% isopropanol: pH 6.0) was applied to the peeled surface using a wire-bar coater. After drying at 50°C for 60 seconds, a 20 μm thick acrylic adhesive layer was applied to fabricate the polarizing film. Otherwise, polarizing and polarizing films were fabricated using the same procedures as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0163] <Comparative Example 5>

[0164] In the above-described fabrication of polarizing and polarizing films, the dyeing bath was changed to an aqueous solution of potassium iodide (15.0 wt% by weight) and ferric sulfate n hydrate (2.0 wt% by weight). Otherwise, the polarizing and polarizing films were fabricated using the same procedures as in Example 1. The results of the above-described measurements and evaluations of the polarizing and polarizing films are shown in Table 1.

[0165]

Claims

1. A polarizing film, wherein a transparent protective film or an optical functional film is laminated to at least one side of the polarizing film. The polarizing film is formed by adsorbing iodine onto a polyvinyl alcohol film and orienting it, and the iodine concentration exceeds 10% by weight. The polarizing film contains a free radical scavenger. The free radical scavenger is selected from one or more compounds chosen from hindered phenolic compounds, hindered amine compounds, phosphorus compounds, sulfur compounds, benzotriazole compounds, benzophenone compounds, hydroxylamine compounds, salicylates, triazine compounds, and compounds having nitryl radicals or nitryl groups. The transparent protective film or the optical functional film is a first film having a moisture permeability of 200 g / (m 2 ·24h) or less, The monomer transmittance of the polarizing film is 41% or less, and satisfies Equation (1): ΔTs (%) = Ts 96 - the condition that the variation ΔTs of the monomer transmittance represented by Ts0 is 0% or more and 5% or less, In the formula (1), Ts0 is a monomer transmittance of a laminate in which a glass plate is attached to the opposite surface of the first film surface of the polarizing film via an adhesive layer, Ts 96 represents a monomer transmittance after the laminate is heat-treated at 105°C for 96 hours.

2. The polarizing film according to claim 1, wherein, The thickness of the polarizing film is less than 10 μm.

3. The polarizing film according to claim 1 or 2, wherein, The weight ratio of the free radical scavenger content to the iodine content, i.e., the free radical scavenger content / iodine content, is 0.01 or more.

4. The polarizing film according to claim 1 or 2 has a polarization degree of 99.98% or higher.

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