TW201902716A - Polarized film and image display device - Google Patents

Abstract

The present invention is a polarizing film provided with a polarizer and a first transparent layer on both surfaces of the polarizer, wherein the sorbed water content of the first transparent layer is less than the sorbed water content of the polarizer, and the first transparent layer functions as a permeation membrane for assisting with the elimination of moisture in the polarizer. This polarizing film is capable of preventing a decrease in the degree of polarization at the edge of the film even in high temperature, high humidity environments.

Description

Polarizing film and image display device

The present invention relates to a polarizing film. The aforementioned polarizing film may be used alone or in the form of a laminated optical film to form an image display device such as a liquid crystal display device (LCD) or an organic EL display device.

BACKGROUND OF THE INVENTION In a liquid crystal display device, it is necessary and indispensable to arrange polarizing films on both sides of a glass substrate that forms the surface of a liquid crystal panel according to its image formation method. The polarizing film is generally one in which a polarizer made of a polyvinyl alcohol-based film and a dichroic material such as iodine is passed through a polyvinyl alcohol-based adhesive on one side or both sides to attach a protective film.

In addition, the polarizing film may be exposed to a severe environment depending on the use or state of use. Therefore, the polarizing film is required to have durability capable of maintaining optical characteristics even under severe environments. For example, some literatures have proposed that a urethane resin having a predetermined storage elastic modulus be provided on at least one side of a polarizer (Patent Documents 1 and 2). According to Patent Documents 1 and 2, the orthogonal transmittance of the polarizing film can be maintained at high temperatures.

Prior Art Literature Patent Literature Patent Literature 1: Japanese Patent Application Laid-Open No. 11-030715 Patent Literature 2: Japanese Patent Application Laid-Open No. 11-183726

Summary of the Invention Problems to be Solved by the Invention In addition to using a polarizing film in a high-temperature environment, it may be used in a high-temperature and high-humidity environment. It is known that under the severe gas environment, the moisture in the gas environment will affect the optical characteristics of the polarizer, and at the end of the polarizing film, the degree of polarization will be greatly reduced. However, when the urethane resin described in Patent Documents 1 and 2 is provided on a polarizer, it is not possible to sufficiently suppress a decrease in the degree of polarization at the ends of the polarizing film.

An object of the present invention is to provide a polarizing film which can suppress the reduction in the degree of polarization at the end portion under a high temperature and high humidity environment.

Another object of the present invention is to provide an image display device having the polarizing film.

Means for Solving the Problem After a positive review by the inventors of the present case, it was found that the above problems can be solved by the following polarizing film and the like, and the present invention has been completed.

That is, the present invention relates to a polarizing film having a polarizer and first transparent layers on both sides of the polarizer. The polarizing film is characterized in that the first transparent layer is at 85 ° C. and 85% RH. The saturated moisture content is lower than the saturated moisture content of the polarizer at 85 ° C. and 85% RH; the first transparent layer serves as a permeable film and functions to help discharge the moisture in the polarizer.

In the polarizing film, the first transparent layer is preferably formed directly on the polarizer.

In the polarizing film, the thickness of the first transparent layer is preferably 3 μm or less.

In the polarizing film, a hardened product of a forming material containing a urethane prepolymer may be used as the first transparent layer, and the urethane prepolymer is a reactant of an isocyanate compound and a polyol. The isocyanate compound is preferably at least one selected from the group consisting of toluene diisocyanate and diphenylmethane diisocyanate.

In the polarizing film, the first transparent layer preferably has a gradient distribution in which the saturated moisture concentration at 85 ° C. and 85% R.H. in the first transparent layer gradually decreases from the polarizer side to the side opposite to the polarizer.

In the polarizing film, the thickness of the polarizer is preferably 10 μm or less.

The polarizing film is preferably: among the first transparent layers of at least one side of the first transparent layer on both sides of the polarizer, a second transparent layer is adjacent to the side opposite to the side having the polarizer; the second transparent layer The saturated moisture content at 85 ° C and 85% RH is lower than the saturated moisture content of the first transparent layer at 85 ° C and 85% RH; the moisture in the polarizer penetrates the first polarizer in order from the polarizer side. A transparent layer and the aforementioned second transparent layer.

In the polarizing film, the second transparent layer may be an adhesive layer.

In the polarizing film, the second transparent layer may be a protective film.

The present invention also relates to an image display device including the polarizing film.

ADVANTAGE OF THE INVENTION Since the polarizer which is a component of a polarizing film is formed of the water-based material, it is easy for the polarizer to absorb moisture in a gaseous environment. Therefore, it is conceivable that when the polarizing film is kept in a high temperature and high humidity environment, the saturated moisture content in the polarizer will increase. As a result, the optical characteristics of the polarizing film tend to decrease. In particular, in a high-temperature and high-humidity environment, there is a large amount of water intrusion into the polarizer, so it is conceivable that at the end of the polarizing film, the degree of polarization will be greatly reduced, and a phenomenon called end discoloration occurs.

The polarizing film of the present invention has first transparent layers on both sides of the polarizer, and the first transparent layer serves as a permeable film and functions to help drain out moisture in the polarizer. The saturated moisture content of the first transparent layer in the high-temperature and high-humidity environment is designed to be lower than that of the polarizer. Therefore, even if moisture in the gas environment has penetrated into the polarizer, the moisture in the polarizer can still be actively It penetrates to the side of the first transparent layer (permeable membrane) having a lower saturated moisture content than the saturated moisture content of the polarizer, so that the moisture in the polarizer can be discharged out of the polarizer by this effect. As described above, the polarizing film of the present invention has the aforementioned first transparent layer, thereby suppressing an increase in the saturated moisture content of the polarizer even in a high-temperature and high-humidity environment, thereby suppressing the amount of discoloration at the ends of the polarizing film.

Mode for Carrying Out the Invention The polarizing film of the present invention will be described below with reference to Figs. 1 to 3. As an example of the polarizing film of the present invention, the polarizing film 11 shown in FIGS. 1 to 3 has a polarizer P and first transparent layers 1a and 1b (permeation film: Membrane function layer that helps water drainage function). As shown in FIG. 1 to FIG. 3, the first transparent layers 1 a and 1 b are directly disposed on the polarizer P, which can suppress the increase in the saturated moisture content of the polarizer under a high temperature and high humidity environment, thereby suppressing the discoloration of the polarizing film ends. And therefore better. The first transparent layers 1a and 1b may be provided with only one of them directly on the polarizer P.

In addition, as an example of the polarizing film of the present invention, as shown in FIG. 2 and FIG. 3, at least at least the first transparent layers 1 a and 1 b on both sides of the polarizer P of the polarizing film 11 may be the polarizing films 12 and 13 shown in FIG. A second transparent layer 2 (2a and / or 2b) is further provided on the one-sided first transparent layers 1a and 1b. The polarizing film 12 of FIG. 2 is a case where a second transparent layer is further provided on the one-sided first transparent layer 1a of the first transparent layers 1a and 1b on both sides; and the polarizing film 13 of FIG. 3 is a first transparent layer 1a and 1b on both sides. In the case where the first transparent layers 1a, 1b on both sides of a transparent layer 11a, 1b are further provided with the second transparent layers 2a, 2b. By placing the second transparent layer 2 (2a and / or 2b) directly on the first transparent layers 1a, 1b, the saturation moisture content of the polarizer in a high-temperature and high-humidity environment can be suppressed from rising, and the end of the polarizing film can be suppressed from discoloring And therefore better.

In addition, in the polarizing films 12 and 13 of the present invention, if an adhesive layer is used as the second transparent layer 2, a separator can be provided on the second transparent layer (adhesive layer). On the other hand, a surface protective film may be appropriately provided on the polarizing films 11 to 13 of the present invention.

<Polarizer> The polarizer is not particularly limited, and various polarizers can be used. Examples of polarizers include adsorption of iodine or dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films. Polychromatic materials and uniaxial stretching, and polyene-based oriented films such as dehydrated products of polyvinyl alcohol or dehydrochlorinated products of polyvinyl chloride. Among these, a polarizer composed of a dichroic substance such as a polyvinyl alcohol film and iodine is more suitable. The thickness of these polarizers is not particularly limited, and is generally about 80 μm or less.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching the polyvinyl alcohol-based film can be dyed by, for example, immersing the polyvinyl alcohol-based film in an aqueous solution of iodine, and stretched to 3 to 7 times its original length. production. If necessary, it may be immersed in an aqueous solution which may contain boric acid, potassium iodide, or the like such as zinc sulfate or zinc chloride. Further, if necessary, the polyvinyl alcohol-based film is immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, dirt and anticaking agents on the surface of the polyvinyl alcohol-based film can be cleaned. In addition, the polyvinyl alcohol-based film can swell and prevent uneven dyeing and the like. The stretching may be performed after dyeing with iodine, or may be extended while dyeing, or may be dyed with iodine after stretching. Stretching can also be performed in an aqueous solution such as boric acid or potassium iodide or in a water bath.

In the present invention, a polarizer having a thickness of 10 μm or less can be used. From the viewpoint of thinning, the thickness of the polarizer is preferably 8 μm or less, more preferably 7 μm or less, and even more preferably 6 μm or less. On the other hand, the thickness of the polarizer is 2 μm or more, and more preferably 3 μm or more. Such thin polarizers have small thickness variations, good visibility, and small dimensional changes, so they have excellent durability against thermal shock.

Examples of thin polarizers include: Japanese Patent No. 4751486, Japanese Patent No. 4751481, Japanese Patent No. 4815544, Japanese Patent No. 5048120, International Publication No. 2014/077599, and International The thin polarizers disclosed in the gazette manual No. 2014/077636, etc., or the thin polarizers obtained by the manufacturing methods described in them are disclosed.

The aforementioned polarizer is preferably constituted so that the optical characteristics represented by the single transmittance T and the polarization degree P satisfy the following formula: P>-(10 ^0.929T-42.4 -1) × 100 (however, T <42.3), or P ≧ 99.9 (however, T ≧ 42.3). In short, a polarizer configured to meet the aforementioned conditions has the performance required for a liquid crystal television display using a large display element. Specifically, the contrast is 1000: 1 or more and the maximum brightness is 500 cd / m ² or more. For other uses, for example, it can be attached to the viewing side of an organic EL display device.

In the manufacturing method including the step of stretching in the state of a laminated body and the dyeing step, from the viewpoint of being capable of being stretched at a high magnification to improve the polarization performance, the aforementioned thin polarizers are described in, for example, Japanese Patent No. 4751486, Japanese Patent No. 4751481 Those described in the specification and Japanese Patent No. 4815544 are preferably prepared by a method including an extension step in an aqueous boric acid solution, and are particularly included as described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544 It is suitable to obtain the method by performing the step of auxiliaryly performing aerial stretching in the boric acid aqueous solution before stretching. These thin polarizers can be produced by a manufacturing method including a step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as a PVA resin) layer and a stretching resin substrate in a state of a laminate and a dyeing step. According to this manufacturing method, even if the PVA-based resin layer is thin, it is supported by the resin base material for stretching, so that it can be stretched without causing unfavorable conditions such as breakage due to stretching.

Generally, the polarizer of the present invention is one having a saturated moisture content of 10 to 40% by weight at 85 ° C and 85% R.H. From the viewpoint of suppressing discoloration of the end portion, the saturation moisture content of the polarizer may be 25% by weight or less, and further may be 18% by weight or less. In addition, under the relationship between the saturated moisture content of the polarizer and the first transparent layer, there is no particular lower limit value as long as the saturated moisture content of the first transparent layer is lower than the saturation moisture content of the polarizer.

The saturation moisture content of the polarizer of the present invention can be adjusted by any appropriate method. The method may be controlled by, for example, adjusting the conditions of the drying step in the manufacturing step of the polarizer.

<First transparent layer> The first transparent layer is a layer that functions as a permeable film to help discharge the moisture in the polarizer. The saturated water content of the first transparent layer at 85 ° C and 85% RH is designed to be higher than that described above. The polarizer has a lower saturated moisture content. The saturated moisture content of the first transparent layer on both sides may be the same, and may be different as long as it is lower than the saturated moisture content of the aforementioned polarizer. The material and thickness of the first transparent layer on both sides are the same, and they may be the same or different.

From the viewpoint of function as a permeable membrane, the difference between the saturated moisture content of the polarizer and the saturated moisture content of the first transparent layer is preferably 1 to 20% by weight, and more preferably 3 to 15% by weight. In addition, even if the difference in the saturated moisture content is too large, there is no problem. On the other hand, if the difference is too small, the function of the permeable membrane cannot be fully exerted. Therefore, it should be controlled within the aforementioned range. The saturated moisture content of the first transparent layer is generally 1 to 10% by weight, and more preferably 3 to 8% by weight.

From the viewpoint of function, thinning, and optical reliability as a permeable membrane, the thickness of the first transparent layer is preferably 3 μm or less, more preferably 2 μm or less, still more preferably 1.5 μm or less, and still more preferably 1 μm or less. If the first transparent layer is too thick, there is a possibility that the first transparent layer may have a thickness, thereby preventing the water from being discharged and failing to function as a permeable membrane. On the other hand, from the viewpoint of ensuring the function as a permeable membrane, the thickness of the first transparent layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and still more preferably 0.3 μm or more.

As the material for forming the first transparent layer, those having transparency and satisfying the saturated moisture content can be used. Examples of the material include a forming material of an urethane prepolymer that is a reactant of an isocyanate compound and a polyol.

The isocyanate compound is, for example, a polyfunctional isocyanate compound, and specific examples thereof include a polyfunctional aromatic isocyanate compound, an alicyclic isocyanate, an aliphatic isocyanate compound, or a dimer thereof.

Examples of the polyfunctional aromatic isocyanate compound include phenylene diisocyanate, toluene 2,4-isocyanate, toluene 2,6-diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene di Isocyanate, stilbene diisocyanate, methylenebis 4-phenyl isocyanate, p-phenylene diisocyanate, etc.

Examples of the polyfunctional alicyclic isocyanate compound include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, and 1,3-bisisocyanate. Methylcyclohexane, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated succinic diisocyanate, hydrogenated diisocyanate, hydrogenated dimethyl cyanate, and the like.

Examples of the polyfunctional aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, and 1,3 -Butyl diisocyanate, dodecyl diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc.

In addition, the polyfunctional isocyanate compound may be one having three or more isocyanate groups such as ginseng (6-isocyanatehexyl) trimer isocyanate.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 2-butanediol. 2-Ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol , 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, stearyl glycol, glycerol, trimethylolpropane, neopentyl tetraol, hexane Triol, polypropylene glycol, etc.

As the aforementioned urethane prepolymer, in the present invention, it is suitable to use a rigid structure having a large proportion of the cyclic structure (benzene ring, cyanurate ring, trimeric isocyanate ring, etc.) in the structure. Structurer. For example, the aforementioned polyfunctional isocyanate compounds may be used singly or in combination of two or more. From the viewpoint of adjusting the saturated moisture content, an aromatic isocyanate compound is preferable. Other polyfunctional isocyanate compounds may be used in combination with an aromatic isocyanate compound. Among the aromatic isocyanate compounds, the isocyanate compound is preferably at least one selected from the group consisting of toluene diisocyanate and diphenylmethane diisocyanate.

The urethane prepolymer is preferably trimethylolpropane-tri-isocyanate and trimethylolpropane-tri-diphenylmethane diisocyanate.

Moreover, the said urethane prepolymer can also be used for a protective group provided with a terminal isocyanate group. Protecting groups include oxime and linamine. The isocyanate group is protected by dissociating the protective group from the isocyanate group by heating, and reacting the isocyanate group.

Furthermore, a reaction catalyst can be used in order to improve the reactivity of an isocyanate group. The reaction catalyst is not particularly limited, but a tin-based catalyst or an amine-based catalyst is desirable. The reaction catalyst may be used singly or in combination of two or more kinds. The amount of the reaction catalyst used is usually 5 parts by weight or less based on 100 parts by weight of the urethane prepolymer. When the amount of the reaction catalyst is large, the cross-linking reaction speed becomes faster and the formed material foams. On the other hand, sufficient adhesiveness cannot be obtained using the foamed forming material. Generally, when a reaction catalyst is used, it is preferably 0.01 to 5 parts by weight, and more preferably 0.05 to 4 parts by weight.

As the tin-based catalyst, either an inorganic system or an organic system can be used, but an organic system is preferred. Examples of the inorganic tin-based catalyst include stannous chloride and tin chloride. The organic tin catalyst preferably has at least one of the following organic groups: an aliphatic group having a skeleton such as a methyl group, an ethyl group, an ether group, and an ester group, an alicyclic group, and the like. Examples include tetra-n-butyltin, tri-n-butyltin acetate, n-butyltin trichloride, trimethyltin hydroxide, dimethyltin dichloride, dibutyltin dilaurate, and the like.

The amine catalyst is not particularly limited. Instead, it is preferable to have at least one such as Organic groups such as alicyclic groups such as pyridine, hydrazones, diazabicycloundecene, and the like. In addition, triethylamine can be mentioned as the amine catalyst. Examples of the reaction catalyst other than the above include cobalt naphthenate and benzyltrimethylammonium hydroxide.

The aforementioned urethane prepolymer is generally used as a solution. The solution may be a solvent system or an aqueous system such as an emulsion, a colloidal dispersion, or an aqueous solution. The organic solvent is not particularly limited as long as the components constituting the forming material can be uniformly dissolved. Examples of the organic solvent include toluene, methyl ethyl ketone, and ethyl acetate. In addition, when preparing an aqueous solution, for example, alcohols such as n-butanol and isopropanol, and ketones such as acetone may be blended. When preparing an aqueous solution, it can be performed by using a dispersant, or by introducing a carboxylate, sulfonate, quaternary ammonium salt, and the like having a low reactivity with an isocyanate group into the urethane prepolymer. Or water-dispersible components such as polyethylene glycol.

In addition to the aforementioned urethane prepolymer, examples of a material for forming the first transparent layer include a cyanoacrylate-based forming material and an epoxy-based forming material.

The formation of the first transparent layer may be appropriately selected according to the type of the forming material. For example, the forming of the first transparent layer may be performed by coating the forming material on a polarizer or a resin film, and then curing. Get a transparent layer. Generally speaking, after the coating is performed, drying is performed at about 30 to 100 ° C., and more preferably at 50 to 80 ° C. for about 0.5 to 15 minutes to form a hardened layer. In addition, when the aforementioned forming material contains an isocyanate component, in order to promote the reaction, an annealing treatment may be performed at about 30 to 100 ° C, more preferably at 50 to 80 ° C for about 0.5 to 24 hours.

The first transparent layer preferably has a structure having a gradient distribution: the saturated water concentration in the first transparent layer at 85 ° C. and 85% R.H. gradually decreases from the polarizer side to the side opposite to the polarizer. The structure can make it function more effectively as a permeable membrane.

<The second transparent layer> In the polarizing film of the present invention, a second transparent layer may be further formed on the first transparent layer. Various layers can be formed as the second transparent layer, but from the viewpoint that the function of the permeable membrane can be more fully exerted, it is preferable to provide a second transparent layer having a saturated moisture content lower than that of the first transparent layer.

From the viewpoint of functioning as a permeable membrane, the difference between the saturated moisture content of the first transparent layer and the saturated moisture content of the second transparent layer is preferably 0.1 to 8% by weight, and more preferably 0.5 to 5% by weight. In addition, even if the aforementioned difference is too large, there is no problem, but on the other hand, if it is too small, the function of the permeable membrane cannot be fully exerted, so it should be controlled within the aforementioned range. In addition, the saturated moisture content of the second transparent layer can be used in a range lower than the saturated moisture content of the first transparent layer. In general, it is preferable to use 0.1 to 8% by weight, and more preferably 0.5 to 5% by weight.

From the viewpoint of functioning as a permeable membrane, the thickness of the second transparent layer is about 1 to 100 μm. It is preferably 2 to 50 μm, more preferably 2 to 40 μm, and more preferably 5 to 35 μm.

The second transparent layer may be formed of a resin film such as an adhesive layer, an adhesive layer, a hard coating layer, or a protective film, for example. From the viewpoint of suppressing discoloration of the end portions of the polarizing film, an adhesive layer is preferred among these. When the second transparent layer is provided on both sides, the thickness of the material of each second transparent layer may be the same or different.

≪Second transparent layer: Adhesive layer 适当 An appropriate adhesive can be used for the formation of the adhesive layer, and there are no particular restrictions on its type. Examples of the adhesive include rubber-based adhesives, acrylic-based adhesives, polysiloxane-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, and the like.

Among these adhesives, those which are excellent in optical transparency, exhibit appropriate adhesion characteristics of wettability, cohesiveness, and adhesiveness, and are excellent in weather resistance and heat resistance are also suitably used. Those exhibiting such characteristics can suitably use an acrylic adhesive.

The method for forming the adhesive layer can be produced by, for example, the following method: the aforementioned adhesive is applied to a separator subjected to a peeling treatment, etc., and the polymerization solvent is dried and removed to form an adhesive layer, and then transferred to A method of a first transparent layer; or a method of coating the aforementioned adhesive on the first transparent layer and drying and removing a polymerization solvent to form the adhesive layer on a polarizer. When applying the adhesive, one or more solvents other than the polymerization solvent may be appropriately added.

Released separators should use silicone release liners. In the step of applying the adhesive of the present invention to the lining material and drying it to form an adhesive layer, a method for drying the adhesive may be an appropriate and appropriate method depending on the purpose. It is preferable to use a method of drying the above-mentioned coating film by heat. The heating and drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature to the above range, an adhesive having excellent adhesive properties can be obtained.

The drying time can be appropriately adopted. The above drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and even more preferably 10 seconds to 5 minutes.

Various methods can be adopted for forming the adhesive layer. Specifically, for example, roll coating, contact roll coating, gravure coating, reverse coating, roll brush, spray cloth, dip roll coating, bar coating, blade coating, air blade coating, Methods such as curtain coating, lip coating, and extrusion coating using a die coater.

The thickness of the adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm. It is preferably 2 to 50 μm, more preferably 2 to 40 μm, and more preferably 5 to 35 μm.

When the aforementioned adhesive layer is exposed, the adhesive layer may also be protected by a peeled sheet (separator) until it is ready for practical application.

Examples of the constituent materials of the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and non-woven cloth, meshes, foamed sheets, and metals. Suitable foils and the like, such as foils and laminates thereof, are preferably used from the viewpoint of excellent surface smoothness.

The plastic film is not particularly limited as long as it can protect the aforementioned adhesive layer, and examples thereof include polyethylene films, polypropylene films, polybutene films, polypentadiene films, polymethylpentene films, and polyvinyl chloride. Film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-ethyl acetate copolymer film, and the like.

The thickness of the aforementioned separator is usually 5 to 200 μm, and preferably about 5 to 100 μm. If necessary, the aforementioned separators may be subjected to mold release and antifouling treatment using polysiloxane-based, fluorine-based, long-chain alkyl-based or fatty acid ammonium-based release agents, silicon dioxide powder, etc. Antistatic treatment such as kneading type and vapor deposition type. In particular, by appropriately performing a peeling treatment such as a polysiloxane treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the separator, the peelability from the adhesive layer can be further improved.

≪Second transparent layer: protective film≫ The material constituting the aforementioned protective film should preferably be excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, and the like. Examples include: polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; cellulose polymers such as diethyl cellulose and triethyl cellulose; polymethyl methacrylate Acrylic polymers such as esters; styrene polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin); and polycarbonate polymers. In addition, the following polymers can also be cited as examples of the polymer forming the protective film: polyethylene, polypropylene, polyolefins having a ring system or a norbornene structure, and polyolefin polymers such as ethylene-propylene copolymers Polymers such as vinyl chloride polymers, nylon and aromatic polyamidoamines, imine polymers, fluorene polymers, polyether fluorene polymers, polyetheretherketone polymers, polystyrene Sulfur-based polymer, vinyl alcohol-based polymer, vinylidene chloride-based polymer, vinyl butyral-based polymer, aryl ester-based polymer, polyoxymethylene-based polymer, epoxy-based polymer, or one of the foregoing polymers Blends and more.

In addition, the protective film may contain one or more arbitrary appropriate additives. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-colorants, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, preferably 50 to 99% by weight, more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, there is a possibility that the thermoplastic resin cannot sufficiently exhibit the originally high transparency and the like.

The protective film may be a retardation film, a brightness enhancement film, a diffusion film, or the like. Examples of the retardation film include those having a front phase retardation of 40 nm or more and / or a thickness direction retardation of 80 nm or more. The front phase difference is usually controlled in the range of 40 ~ 200nm, and the thickness direction phase difference is usually controlled in the range of 80 ~ 300nm. When a retardation film is used as a protective film, since this retardation film can also function as a protective film for a polarizer, thickness reduction can be achieved.

Examples of the retardation film include a birefringent film obtained by subjecting a thermoplastic resin film to uniaxial or biaxial stretching. The above-mentioned stretching temperature, stretching ratio, and the like can be appropriately set depending on the phase difference 値, the film material, and the thickness.

The thickness of the protective film can be appropriately determined, but is generally about 1 to 500 μm from the viewpoints of workability such as strength and workability, and thinness. It is particularly preferably from 1 to 300 μm, more preferably from 5 to 200 μm, more preferably from 5 to 150 μm, and especially from a thin type of from 20 to 100 μm.

Functional layers such as a hard coat layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer, and even an anti-glare layer may be provided on the surface of the protective film that is not attached to the polarizer. In addition, the functional layers such as the hard coating layer, the anti-reflection layer, the anti-adhesion layer, the diffusion layer, or the anti-glare layer may be provided in addition to the protective film itself, or may be separately provided as a separate body from the protective film.

The protective film (second transparent layer) can be directly bonded to the first transparent layer.

<Surface protection film> The polarizing film of the present invention may be provided with a surface protection film. The surface protection film usually has a base film and an adhesive layer, and the polarizer is protected through the adhesive layer.

From the viewpoints of inspection and management, etc., the base film of the surface protection film can be selected to have an isotropic or nearly isotropic film material. Examples of the film material include polyester resins such as polyethylene terephthalate films, cellulose resins, acetate resins, polyether fluorene resins, polycarbonate resins, polyamide resins, Transparent polymer such as polyimide resin, polyolefin resin, and acrylic resin. Among them, polyester resins are preferred. The base film can be used as a laminate of one or more film materials, or an extension of the aforementioned film can be used. The thickness of the substrate film is usually 500 μm or less, preferably 10 to 200 μm.

The adhesive for forming the adhesive layer of the surface protection film may be appropriately selected from (meth) acrylic polymers, polysiloxane polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based polymers, or A polymer such as a rubber system is used as an adhesive for the base polymer. From the viewpoints of transparency, weather resistance, and heat resistance, an acrylic adhesive using an acrylic polymer as a base polymer is preferable. The thickness (dry film thickness) of the adhesive layer can be determined according to the required adhesive force. It is usually about 1 to 100 μm, and preferably 5 to 50 μm.

In addition, for the surface protection film, a peeling treatment layer may be provided through a low-adhesion material such as a polysiloxane treatment, a long-chain alkyl treatment, or a fluorine treatment on the opposite side of the surface of the base film having the adhesive layer.

<Other optical layers> When the polarizing film of the present invention is actually used, it can be used as an optical film laminated with other optical layers. There is no particular limitation on the optical layer, and one or more layers such as a reflection plate and a transflective plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film can be used. An optical layer such as a liquid crystal display device is formed. Especially preferred is: reflective polarizing film or transflective polarizing film formed by laminating a reflective plate or a transflective reflective plate on the polarizing film of the present invention, and elliptically polarized light formed by laminating a retardation plate on a polarizing film. A film or a circularly polarizing film, a wide-angle polarizing film made by laminating a viewing angle compensation film on a polarizing film, or a polarizing film made by laminating a brightness enhancement film on a polarizing film.

An optical film formed by laminating the above-mentioned optical layers on a polarizing film can also be formed by sequentially laminating them in the manufacturing process of a liquid crystal display device, etc., but those who have been laminated in advance to form an optical film have aspects such as quality stability and assembly operations. It has the advantage of improving the manufacturing steps of the liquid crystal display device and the like. For lamination, an appropriate bonding mechanism such as an adhesive layer can be used. When following the above-mentioned polarizing film and other optical films, their optical axes can be set to an appropriate arrangement angle in accordance with the desired retardation characteristics and the like.

The polarizing film or optical film of the present invention can be suitably used for forming various image display devices such as a liquid crystal display device and an organic EL display device. The formation of the liquid crystal display device can be performed in accordance with conventional knowledge. That is, a liquid crystal display device is generally formed by appropriately assembling and mounting a driving circuit and the like with a liquid crystal cell, a polarizing film, an optical film, and a component such as a lighting system according to demand. In the present invention, in addition to using the polarizing film of the present invention, The optical film is not particularly limited except for this point, and can be known in accordance with conventional methods. The liquid crystal cell may be any type such as an IPS type or a VA type, but an IPS type is particularly preferable.

A liquid crystal display device in which a polarizing film or an optical film is arranged on one or both sides of a liquid crystal cell, or a suitable liquid crystal display device using a backlight or a reflection plate as an illumination system can be formed. At this time, the polarizing film or optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. When polarizing films or optical films are arranged on both sides, they may be the same or different. In addition, when forming a liquid crystal display device, one or more layers such as a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a fluorene array, a lens array sheet, a light diffusion plate, Appropriate parts such as backlights. Examples

The present invention will be illustrated by the following examples, but the present invention is not limited to the examples shown below. In addition, parts and% in each case are a basis of weight. Below, all room temperature storage conditions not specified are 23 ° C and 65% R.H.

(Production of thin polarizer A) On one side of a substrate of amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA-co-PET) film (thickness: 100 μm) with a water absorption of 0.75% and a Tg of 75 ° C Corona treatment was applied, and the corona-treated surface was coated at 25 ° C with polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetamidine modified PVA at a ratio of 9: 1. (Polymerization degree: 1200, acetamidine modification degree: 4.6%, saponification degree: 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. under the trade name "Gohsefimer Z200") and dried to form a PVA resin with a thickness of 11 μm Layer to make a laminated body. The obtained laminated body was subjected to a free-end uniaxial extension of 2.0 times in the longitudinal direction (long side direction) between rollers of different peripheral speeds in an oven at 120 ° C (air-assisted extension). Next, the laminated body was immersed in an insoluble bath (aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30 ° C. for 30 seconds (insolubilization treatment). Next, it was immersed in a dyeing bath at a liquid temperature of 30 ° C. while adjusting the iodine concentration and immersion time so that the polarizing plate had a predetermined transmittance. In this example, it was immersed in an aqueous iodine solution obtained by mixing 0.2 parts by weight of iodine and 1.0 part by weight of potassium iodide with respect to 100 parts by weight of water for 60 seconds (dyeing treatment). Next, it was immersed in a crosslinking bath (aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30 ° C (crosslinking treatment) ). Thereafter, the laminated body was immersed in a boric acid aqueous solution at a liquid temperature of 70 ° C. (aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) between rollers of different peripheral speeds. Uniaxial stretching was performed in the longitudinal direction (long-side direction) so that the total stretching ratio was 5.5 times (stretching in water). Then, the laminated body was immersed in a washing bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 30 ° C (washing treatment). An optical film laminate including a polarizer having a thickness of 5 μm was prepared in the above manner.

(Production of Polarizer B (Polarizer with 12 μm Thickness)) A 30 μm thick polyvinyl alcohol film with an average polymerization degree of 2400 and a saponification degree of 99.9 mol% was immersed in warm water at 30 ° C. for 60 seconds to swell. Next, the film was dyed while being immersed in an aqueous solution containing 0.3% of iodine / potassium iodide (weight ratio = 0.5 / 8), and stretched to 3.5 times. Thereafter, it was stretched in a boric acid ester aqueous solution at 65 ° C. so that the total stretching ratio became 6 times. After stretching, it was dried in an oven at 40 ° C. for 3 minutes to obtain a PVA-based polarizer. The thickness of the obtained polarizer was 12 μm.

(Production of protective film) Protective film: A corona treatment is applied to the easy-to-treat surface of a (meth) acrylic resin film having a lactone ring structure with a thickness of 40 μm, and then used.

<Forming material of the first transparent layer (barrier layer)> Forming material A: A 75% ethyl acetate solution of a urethane prepolymer composed of toluene diisocyanate and trimethylolpropane (Tosoh (East Cao) Co., Ltd., trade name "CORONATE L") 100 parts, add 0.1 parts of dioctyl dilaurate catalyst (manufactured by Tokyo Fine Chemical Co., Ltd., trade name "Embilizer OL-1", and methyl isobutyl A ketone is used as a solvent to prepare a urethane prepolymer coating solution having a solid concentration of 10%. Forming material B: A urethane prepolymer composed of diphenylmethane diisocyanate and trimethylolpropane is used. A 75% ethyl acetate solution (manufactured by Tosoh Corporation, trade name "CORONATE 2067") was used to prepare a coating solution using the same catalyst and solvent as the forming agent A. Forming material C: Use A 75% ethyl acetate solution of a urethane prepolymer composed of hexamethylene diisocyanate and trimethylolpropane (manufactured by Tosoh Corporation under the trade name "CORONATE HL"). The coating liquid is prepared by using the same catalyst and solvent as the forming agent A. Forming material D: urethane acrylate To 80 parts of resin (manufactured by Nihon Kogyo Co., Ltd. under the product name "Purple UV-1700"), hydroxyethyl acrylamide (manufactured by Hingren Co., Ltd. under the product name "HEAA") and a photopolymerization initiator (manufactured by Ciba Japan Co., Ltd.) were added. , Product name "IRGACURE 907"), and methyl isobutyl ketone was used as a solvent to prepare a urethane acrylate coating liquid having a solid content concentration of 10%.

<Forming a second transparent layer (adhesive layer)> (Adhesive preparation) 100 parts of butyl acrylate, 3 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate, and 0.3 part of 2,2´-azobisisobutyronitrile , Together with ethyl acetate, add it to a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirring device to prepare a solution. Next, the solution was stirred while blowing nitrogen gas into the solution, and reacted at 55 ° C. for 8 hours to prepare a solution containing an acrylic polymer having a weight average molecular weight of 2.2 million. Then, ethyl acetate was added to the solution containing the acrylic polymer to prepare an acrylic polymer solution having a solid content concentration adjusted to 30%.

With respect to 100 parts of the solid content of the aforementioned acrylic polymer solution, a cross-linking agent containing a compound having an isocyanate group as a main component as a cross-linking agent (manufactured by Japan Polyurethane Co., Ltd., trade name "CORONATE L") is sequentially blended. ) 0.5 parts, 0.075 parts with γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "KMB-403") as a silane coupling agent to prepare an adhesive solution. The above adhesive solution was applied to the surface of a release sheet (separator) made of a polyethylene terephthalate film (thickness: 38 μm) so that its thickness after drying was 20 μm. And allowed to dry to form an adhesive layer.

Example 1 <Preparation of polarizing film with first transparent layer on both sides> After forming the material A of the first transparent layer on a surface of the polarizer A of the optical film laminate with a bar coater, it was performed at 60 ° C. A 12-hour heat treatment was performed to form a urethane resin layer having a thickness of 1 μm. Next, after the amorphous PET substrate was peeled off, the forming material A of the first transparent layer was applied to the peeling surface (polarizer) with a bar coater, and then subjected to a heat treatment at 60 ° C. for 12 hours, whereby A 1 μm-thick urethane resin layer was formed, and a polarizing film having a first transparent layer on both sides was produced. The optical properties of the obtained polarizing film were 42.8% for a single transmittance and 99.99% for a polarization degree.

<Polarizing film with first and second transparent layers: making a polarizing film with an adhesive layer> Next, the first transparent layers on both sides of the above-mentioned polarizing film are bonded to each other and formed on the release sheet (separation piece). The adhesive layer on the treated surface was peeled off, and a polarizing film with an adhesive layer on both sides was produced.

Examples 2 to 3 and Comparative Examples 1 to 6 The types of polarizers, the forming material of the first transparent layer, and the thickness were changed to those shown in Table 1 in the same manner as in Example 1. , And a single-sided protective polarizing film with a first transparent layer and a polarizing film with an adhesive layer on both sides were produced. The optical properties of the obtained single-sided protective polarizing film are that the monomers have a transmittance of 42.8% and a polarization degree of 99.99%.

In Comparative Examples 1 and 4, the first transparent layer was not formed. The formation of the first transparent layer in Comparative Example 3 was performed by applying the above-mentioned forming agent D with a bar coater, and then heating at 60 ° C. for 1 minute. After the heating, the coating layer was irradiated with ultraviolet light having a cumulative light amount of 300 mJ / cm ² with a high-pressure mercury lamp to form an urethane acrylate resin layer having a thickness of 1 μm. In Comparative Examples 4 and 5, a polarizer B (thickness: 12 μm) was used instead of the polarizer A (thickness: 5 μm).

Example 4 <Preparation of polarizing film with first and second transparent layers> After the formation material A of the first transparent layer was applied to the surface of the polarizer A of the optical film laminate with a bar coater, the coating was applied. A good forming agent A was laminated with the above-mentioned protective film ((meth) acrylic resin film) and subjected to a heat treatment at 60 ° C for 12 hours, thereby producing and forming a urethane resin layer having a thickness of 1 μm ( The first transparent layer) is a laminated protective film layer (second transparent layer). Next, after peeling the amorphous PET substrate, the formation material A of the first transparent layer was applied to the release surface (polarizer) by a bar coater, and then the protective film was attached to the coated surface. The forming agent A was heat-treated at 60 ° C. for 12 hours, thereby forming an urethane resin layer and a protective film layer having a thickness of 1 μm, and a first transparent layer and a second layer were formed on both sides. A polarizing film with a transparent layer. The optical properties of the obtained polarizing film were 42.8% for a single transmittance and 99.99% for a polarization degree.

The polarizing films with the first and second transparent layers prepared in the above examples and comparative examples were evaluated as follows. The results are shown in Table 1.

<Measurement of Saturated Moisture Content of Polarizer> The polarizers prepared in the examples and comparative examples were individually taken out before bonding, and a sample of about 50 mg was taken. Using a moisture adsorption and desorption measuring device (IGA-Sorp, manufactured by Hiden), the sample was left in an environment of 85 ° C and 0% RH until the weight did not change, and the weight after the moisture was completely removed was measured (W1 ), And then placed in an environment of 85 ° C and 85% RH, and observed its weight change. And the weight (W2) was measured at the time point (saturated state) when the weight change of the sample stopped. The saturated moisture content was measured by the following formula.

<Measurement of the saturated moisture content of the first transparent layer> The first transparent layer forming material prepared in the examples and comparative examples was applied to an aluminum foil with a bar coater to a thickness of 10 μm. Example and Comparative Example After the first transparent layer was formed in the same manner, it was cut into a size of 10 × 10 mm, and a sample was taken. Using a moisture adsorption and desorption measuring device (IGA-Sorp, manufactured by Hiden), the sample was left in an environment of 85 ° C and 0% RH until the weight did not change, and the weight after the moisture was completely removed was measured (W1 ), And then placed in an environment of 85 ° C and 85% RH, and observed its weight change. And the weight (W2) was measured at the time point (saturated state) when the weight change of the sample stopped. The weight of the aluminum foil of the same size cut out beforehand was subtracted from each weight, and the saturated moisture content was measured by the following formula.

≪Second transparent layer: adhesive layer≫ A sample of about 50 mg was taken from the adhesive layer of the polarizing film with an adhesive layer produced in the examples and comparative examples. Using a moisture absorption and desorption measuring device (IGA-Sorp, manufactured by Hiden), the sample was left in an environment of 85 ° C and 0% RH until the weight did not change, and the weight after the moisture was completely removed was measured (W1 ), And then placed in an environment of 8585% RH, and observed the change in weight. And the weight (W2) was measured at the time point (saturated state) when the weight change of the sample stopped. The saturated moisture content was measured by the following formula.

≪Second transparent layer: protective film≫ Cut the protective film to a size of 10 × 10mm and take a sample. Using a moisture adsorption and desorption measuring device (IGA-Sorp, manufactured by Hiden), the sample was left in an environment of 85 ° C and 0% RH until the weight did not change, and the weight after the moisture was completely removed was measured (W1 ), And then placed in an environment of 85 ° C and 85% RH, and observed its weight change. And the weight (W2) was measured at the time point (saturated state) when the weight change of the sample stopped. The saturated moisture content was measured by the following formula.

[Mathematical formula 1]

＜ Transparent transmittance T and polarization degree P of polarizers ＞ The single transmittance T and polarized light of the obtained single-sided protective polarizing film were measured using a spectroscopic transmittance tester (Dot-3c of Murakami Color Technology Research Institute) with an integrating sphere. Degree P. In addition, the degree of polarization P is the transmittance (parallel transmittance: Tp) when two identical polarizing films are overlapped in parallel with their transmission axes in parallel, and the transmittance (orthogonal transmission) when they are orthogonally overlapped with their transmission axes. Rate: Tc) is calculated by applying the following formula. Polarization P (%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100 The transmittances are set so that the full polarized light obtained through the Glan-Taylor 稜鏡 polarizer is 100% The Y value obtained by correcting the optical performance of the 2-degree field of view (C light source) of JIS Z8701 is expressed.

(Preparation of Evaluation Samples) The polarizing films with first and second transparent layers (polarizing films with adhesive layers on both sides) prepared in Examples 1 to 3 and Comparative Examples 1 to 6 were single-sided After the release sheet is peeled off, the above protective film is bonded to the exposed adhesive layer, and it is cut into 50mm × 50mm, and then bonded to 1.2 ~ 1.5mm thick alkali glass (Matsuba Glass Co., Ltd., glass Sheet) to make a sample. The polarizing film with the first and second transparent layers prepared in Example 4 is an adhesive layer formed on the release-treated surface of the release sheet (separator) (Example 1). The second transparent layer (such as the second transparent layer) is adhered to the second transparent layer (protective film) on one side, and it is cut into 50mm × 50mm, and it is adhered to 1.2 ~ 1.5mm thick alkali glass (Matsuba Glass Co., Ltd., Slide), and a sample is made.

<Confirm the moisture gradient in the first transparent layer> Put the above sample in a closed container and put a sufficient amount of heavy water that will not completely volatilize during the test. After sealing the container, keep the container at a high temperature environment with 80 ° C. After 500 hours, immediately after taking it out, freeze it to below -100 ° C to obtain a sample with heavy water ions immobilized. For this sample immobilized with heavy water, the protective film was removed by etching with Ar gas cluster ions from the protective film side, and then a TOF-SIMS analysis was performed to measure the distribution of heavy water ions (D-) in the depth direction. Water gradient in transparent layer. When a water gradient was confirmed (with a permeable membrane function), it was evaluated as "0", and when a water gradient was not confirmed (without a permeable membrane function), it was evaluated as "x". Device: ULVAC-PHI, TRIFT-V Etching ions: Ar gas cluster ion irradiation Primary ion: Bi ₃ ^{2 +} Primary ion acceleration voltage: 30kV Measuring electrode: Negative ion Measuring temperature: -100 ° C or less Measuring area: 100μm square

<Durability> After the sample was kept in a high-temperature, high-humidity environment at 85 ° C and 85% RH for 500 hours, it was left at room temperature (23 ° C and 65% RH), and then an interference phase difference microscope (manufactured by Olympus) was used under the following conditions. , Product name "MX-61L") to measure the amount of discoloration at the end. The amount of fading at the end is on the diagonal of the four corners of the sample. In the part where the color becomes lighter than the center, the straight line distance between the corner closest to the center and the corner is determined as the amount of fading at the end. The average of the four corners was determined as the amount of discoloration at the end of the sample. Device: Olympus, MX-61L Measurement conditions Lens magnification: 5 times ISO: 200 Shutter speed: 1/100 Reflected light amount: scale 0 White balance: Automatic transmitted light controller: LG-PS2 Transmitted light amount: scale 5 Transmitted light polarized light Orientation: The direction where the transmission axis of the polarizing film is orthogonally polarized. "Unable to measure" in Table 1 means that there is a measurement area (faded area) outside the field of view of the optical microscope that is measuring the end discoloration.

[Table 1]

P‧‧‧Polarizer

1a, 1b ‧‧‧ the first transparent layer

2, 2a, 2b‧‧‧Second transparent layer (adhesive layer)

11, 12, 13‧‧‧polarized film

FIG. 1 is an example of a schematic cross-sectional view of a polarizing film of the present invention. FIG. 2 is an example of a schematic cross-sectional view of a polarizing film of the present invention. FIG. 3 is an example of a schematic cross-sectional view of a polarizing film of the present invention.

Claims (11)

A polarizing film includes a polarizer and first transparent layers on both sides of the polarizer. The polarizing film is characterized in that the saturated moisture content of the first transparent layer at 85 ° C and 85% RH is higher than that of the polarizer. The saturated moisture content is lower at 85 ° C and 85% RH; the first transparent layer serves as a permeable film, and functions to help discharge the moisture in the polarizer. The polarizing film according to claim 1, wherein the first transparent layer is directly formed on the polarizer. The polarizing film of claim 1 or 2, wherein the thickness of the first transparent layer is 3 μm or less. The polarizing film according to any one of claims 1 to 3, wherein the first transparent layer is a hardened material of a forming material containing a urethane prepolymer, and the urethane prepolymer is an isocyanate compound and a polyhydric Alcohol reactants. The polarizing film according to claim 4, wherein the isocyanate compound contains at least one selected from the group consisting of toluene diisocyanate and diphenylmethane diisocyanate. The polarizing film according to any one of claims 1 to 5, wherein the first transparent layer has a gradient distribution: the saturated water concentration in the first transparent layer at 85 ° C and 85% RH is from the polarizer side toward and The opposite side of the polarizer is gradually lowered. The polarizing film according to any one of claims 1 to 6, wherein the thickness of the aforementioned polarizer is 10 μm or less. The polarizing film according to any one of claims 1 to 7, wherein the first transparent layer of at least one side of the first transparent layer provided on both sides of the polarizer has a first transparent layer adjacent to the side opposite to the side having the polarizer. Two transparent layers; the saturated moisture content of the second transparent layer at 85 ° C and 85% RH is lower than the saturated moisture content of the first transparent layer at 85 ° C and 85% RH; the moisture in the polarizer is from the foregoing The polarizer side sequentially penetrates the first transparent layer and the second transparent layer. The polarizing film according to claim 8 or 9, wherein the second transparent layer is an adhesive layer. The polarizing film according to claim 8 or 9, wherein the second transparent layer is a protective film. An image display device having a polarizing film according to any one of claims 1 to 10.