TW201903442A - Polarized film and image display device - Google Patents

Abstract

The present invention is a polarizing film provided with a polarizer, a first transparent layer on one surface of the polarizer, and a second transparent layer on the other surface of the polarizer, wherein the sorbed water content of the first transparent layer is less than the sorbed water content of the polarizer, the first transparent layer functions as a permeation membrane for assisting with the elimination of moisture in the polarizer, and the sorbed water content of the second transparent layer is 5 wt% or less. 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, a first transparent layer on one side of the polarizer, and a second transparent layer on the other side of the polarizer. It is characterized in that the saturated moisture content of the first transparent layer at 85 ° C. and 85% RH is lower than the saturated moisture content of the polarizer at 85 ° C. and 85% RH; the first transparent layer is a permeable membrane to help The function of discharging the moisture in the polarizer; the saturated moisture content of the second transparent layer at 85 ° C. and 85% RH is 5% by weight or less.

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: the first transparent layer has a third transparent layer adjacent to the side opposite to the side having the polarizer; the saturated moisture content of the third transparent layer at 85 ° C and 85% RH is higher than that of the first transparent layer; The saturated layer has a lower saturated moisture content at 85 ° C and 85% RH; the moisture in the polarizer penetrates the first transparent layer and the third transparent layer in order from the polarizer side.

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

The polarizing film may have the first transparent layer only on one side of the polarizer, and may have a protective film on the other side of the polarizer.

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

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 a first transparent layer on one side of the polarizer, and the first transparent layer serves as a permeable film, and functions to help discharge 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 gaseous environment has penetrated into the polarizer, the moisture in the polarizer can still be made active. 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. On the other hand, the other side of the polarizer has a second transparent layer with a saturated moisture content of 5 wt% or less. The second transparent layer with a low saturated moisture content can inhibit moisture from entering the polarizer, and at the same time hinder moisture from The aforementioned polarizer P is diffused, so that the moisture of the polarizer can be penetrated toward the first transparent layer (permeation film) side. As described above, the polarizing film of the present invention has the first transparent layer and the second transparent layer, whereby the saturation moisture content of the polarizer can be suppressed from increasing even under a high-temperature and high-humidity environment, and the ends of the polarizing film can be suppressed. Amount of fading.

Modes for Carrying Out the Invention The polarizing film of the present invention will be described below with reference to Figs. 1 to 4. The polarizing film of the present invention, for example, the polarizing film 11 shown in FIG. 1 to FIG. 4, has a polarizer P and a first transparent layer 1 (a permeable film: a layer having a function of a film that can help water discharge ). In addition, in FIG. 1 to FIG. 4, the case where the polarizer P has a first transparent layer 1 on one side and a second transparent layer 2 with a saturated moisture content of 5 wt% or less on the other side is exemplified. . In addition, as shown in FIGS. 1 to 4, the first transparent layer 1 is directly disposed on the polarizer P, which can suppress an increase in the saturated moisture content of the polarizer under a high-temperature and high-humidity environment, thereby suppressing the end of the polarizing film from fading. And therefore better.

In addition, the polarizing film of the present invention may be, for example, the polarizing film 12 shown in FIG. 2, and a third transparent layer 3 may be further disposed on the first transparent layer 1 of the polarizing film 11. Providing the third transparent layer 3 directly on the first transparent layer 1 can suppress the increase in the saturated moisture content of the polarizer in a high-temperature and high-humidity environment, and can thereby suppress the discoloration of the end portion of the polarizing film.

On the other hand, the polarizing film of the present invention can be a polarizing film 13 as shown in FIG. 3, and a protective film 4 is provided on the second transparent layer 2 of the aforementioned polarizing film 11. When the protective film 4 is used, the protective film 4 (especially a material having a low moisture permeability) and the second transparent layer 2 can prevent moisture from diffusing from the aforementioned polarizer P. Therefore, the present invention is preferred to have only one side of the polarizer P The single-sided protective polarizing film of the protective film 4 is applied. FIG. 4 shows a case where a third transparent layer 3 is provided on the first transparent layer 1 of the polarizing film 13.

In addition, in the polarizing films 12 and 14 of the present invention, if an adhesive layer is used as the third transparent layer 3, a separator may be provided on the third transparent layer (adhesive layer). On the other hand, a surface protective film may be appropriately provided on the polarizing films 11 to 14 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.

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 tetramethyl succinic diisocyanate, etc.

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.

<Second transparent layer> The second transparent layer is a layer having a saturated moisture content at 85 ° C and 85% R.H. adjusted to 5 wt% or less. The saturated moisture content of the second transparent layer is preferably 4% by weight or less, and more preferably 3.5% by weight or less. On the other hand, there is no particular lower limit for the saturated moisture content of the second transparent layer.

The aforementioned second transparent layer may be, for example, an interposer such as an adhesive layer, an adhesive layer, a primer layer (primer layer) applied between the polarizer and the protective film. In addition, it can be applied to an easy-adhesive layer of a protective film. In addition, an easy-adhesive layer or an activation treatment may be provided on the protective film, and the easy-adhesive layer and the adhesive layer may be laminated.

As the material for forming the second transparent layer, those having transparency and functioning as the interposer can be used. At this time, it is expected that the two can be laminated without an air gap by an interposer.

The adhesive layer is formed of an adhesive. The type of the adhesive is not particularly limited, and various substances can be used. The aforementioned adhesive layer is not particularly limited as long as it is optically transparent. Adhesives in various forms such as water-based, solvent-based, hot-melt adhesive, and active energy ray hardening types can be used, but water-based adhesives or active energy rays are used. A hardening type adhesive is suitable.

Examples of the adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, and water-based polyesters. The water-based adhesive is usually used as an adhesive composed of an aqueous solution, and usually contains 0.5 to 60% by weight of a solid content.

The active energy ray-curable adhesive is an adhesive that hardens with active energy rays such as electron rays and ultraviolet (radical-curable, cation-curable). For example, it can be used in the form of electron-ray-curable and ultraviolet-curable. As the active energy ray-curable adhesive, for example, a photoradical-curable adhesive can be used. When a photoradical-curable active energy ray-curable adhesive is used as an ultraviolet-curable adhesive, the adhesive contains a radical polymerizable compound and a photopolymerization initiator.

The coating method of the adhesive can be appropriately selected according to the viscosity or the target thickness of the adhesive. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse, or lithography), a bar reverse coater, a roll coater, a die coater, a bar coater, and a bar coater. Machine and so on. In other respects, a dip coating method or the like can be suitably used for the coating.

In addition, in the case where a water-based adhesive is used for the application of the adhesive, the thickness of the adhesive layer to be finally formed is preferably 30 to 300 nm. The thickness of the aforementioned adhesive layer is more preferably 60 to 250 nm. On the other hand, when using an active energy ray hardening type adhesive, it is preferable to perform it so that the thickness of the said adhesive layer may become 0.1-200 micrometers. It is more preferably 0.5 to 50 μm, and more preferably 0.5 to 10 μm.

The easy-adhesion layer can be formed of various resins having, for example, a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a polysiloxane, a polyamide skeleton, and a polyimide skeleton. , Polyvinyl alcohol skeleton, etc. These polymer resins can be used singly or in combination of two or more kinds. Moreover, you may add another additive when forming an easy-adhesion layer. Specifically, stabilizers such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat-resistant stabilizer can be used.

The easy-adhesive layer is usually provided on the protective film in advance, and the easy-adhesive layer side of the protective film is laminated with the polarizer through the adhesive layer. The formation of the easy-adhesive layer can be performed by applying a known material to the protective film and drying it. The forming material of the easy-adhesion layer is usually adjusted to take into account the thickness after drying, the smoothness of the coating, and the like, and the solution is diluted to an appropriate concentration. The thickness of the easy-adhesive layer after drying should be 0.01 to 5 μm, more preferably 0.02 to 2 μm, and more preferably 0.05 to 1 μm. In addition, the easy-adhesion layer may be provided in multiple layers. At this time, the total thickness of the easy-adhesion layer should also fall within the above range.

The adhesive layer is formed of an adhesive. Various adhesives can be used, and examples include rubber-based adhesives, acrylic-based adhesives, polysiloxane-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, and polyvinyl pyrrolidine. Ketone-based adhesives, polypropylene amidamine-based adhesives, cellulose-based adhesives, and the like. The adhesive base polymer can be selected according to the type of the adhesive. Among the above-mentioned adhesives, acrylic adhesives are preferably used from the viewpoints of excellent optical transparency, exhibiting adhesive properties of appropriate wettability, cohesiveness, and adhesiveness, and excellent weather resistance and heat resistance.

A primer layer (primer layer) is formed to improve the adhesion between the polarizer and the protective film. The material constituting the primer layer is not particularly limited as long as it can exert a certain degree of strong adhesion to both the base film and the polyvinyl alcohol-based resin layer. For example, a thermoplastic resin excellent in transparency, thermal stability, and extensibility can be used. Examples of the thermoplastic resin include an acrylic resin, a polyolefin resin, a polyester resin, a polyvinyl alcohol resin, or a mixture thereof.

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

From the viewpoint of function as a permeable membrane, the difference between the saturated moisture content of the first transparent layer and the saturated moisture content of the third 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 third transparent layer is preferably used in a range lower than the saturated moisture content of the first transparent layer. Generally speaking, it is preferable to use 0.1 to 8%, and more preferably 0.5 to 5 % By weight.

From the viewpoint of functioning as a permeable membrane, the thickness of the third 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 third transparent layer may be formed of, for example, an adhesive layer, an adhesive layer, a hard coat layer, or a resin film such as a protective film. From the viewpoint of suppressing discoloration of the end portions of the polarizing film, an adhesive layer is preferred among these.

An appropriate adhesive can be used for the formation of the adhesive layer, and there is no particular limitation on the type thereof. 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 mold release agents, silicon dioxide powder, and the like, and coating-type, 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.

<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.

It is optional to set the first transparent layer of the present invention on the side to which the aforementioned protective film can be applied based on a polarizer. Therefore, from the viewpoint of suppressing the intrusion of moisture from the protective film side, the material of the aforementioned protective film should be an acrylic with low moisture permeability Polymers, polyolefin-based polymers, etc.

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.

<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 on which the adhesive layer is provided.

<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. 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 holmium 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., 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.

(Protective film) Acrylic acid: Corona treatment is applied to the easy-to-adhesive surface of a (meth) acrylic resin film having a lactone ring structure with a thickness of 40 μm, and then used. TAC: A triethyl cellulose resin film manufactured by Fujifilm, with a product name "TJ40" and a thickness of 40 µm was used. COP: A cycloolefin-based resin film with a product name of "ZeonorFilm" manufactured by Japan Zeon Corporation and having a thickness of 25 µm was 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 material 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 Nippon Gosei Co., Ltd., product name "Purple UV-1700"), N-hydroxyethyl acrylamide and a photopolymerization initiator (IRGACURE 907, manufactured by BASF) were added, and methyl isobutyl A ketone is used as a solvent to prepare a urethane acrylate coating liquid having a solid concentration of 10%. Forming material E: In an urethane prepolymer composed of toluene diisocyanate and trimethylolpropane To 50 parts of 75% ethyl acetate solution (manufactured by Tosoh Corporation, trade name "CORONATE L"), an urethane prepolymer composed of a diisocyanate and trimethylolpropane was added. 50 parts of 75% ethyl acetate solution (manufactured by Mitsui Takeda Chemicals Co., Ltd. under the trade name "TAKENATE D110N") and dioctyl dilaurate catalyst (manufactured by Tokyo Seika Co., Ltd. under the trade name "Embilizer OL-1") 0.1 And using methyl isobutyl ketone as a solvent to prepare a urethane prepolymer coating solution having a solid content concentration of 35%.

<Forming material of the second transparent layer (barrier layer)> (Forming material a: Preparation adhesive a) 10 parts by weight of N-hydroxyethyl acrylamide, acryl 30 parts by weight of phthaloline, 45 parts of 1,9-nonanediol diacrylate, 10 parts of acrylic oligomer (ARUFON UP1190, manufactured by Toa Kosei) polymerized by polymerization of (meth) acrylic monomer, photopolymerization initiation 3 parts of an agent (IRGACURE 907, manufactured by BASF) and 2 parts of a polymerization initiator (KAYACURE DETX-S, manufactured by Nippon Kayaku Co., Ltd.) were mixed to prepare an ultraviolet curing adhesive.

(Forming material b: Preparation of adhesive b) 40 parts by weight of N-hydroxyethylacrylamide (HEAA), acryl 60 parts of phthaloline was mixed with 3 parts by weight of a photopolymerization initiator (IRGACURE 819, manufactured by BASF) to prepare an ultraviolet curing adhesive.

(Forming agent c: preparing adhesive c and forming an adhesive layer) 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, and Ethyl acetate was added 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 the thickness after drying was 5 μm. And allowed to dry to form an adhesive layer.

<Forming a third transparent layer (adhesive layer)> The adhesive solution prepared by the above-mentioned forming agent c was applied to a peeled polyethylene terephthalate so that its thickness after drying was 20 μm. The surface of the release sheet (separator) composed of a diester film (thickness: 38 μm) was dried to form an adhesive layer.

Example 1 <Production of a single-sided protective polarizing film> The surface of the polarizing film A of the optical film laminate was coated with the ultraviolet curing adhesive a such that the thickness of the adhesive layer after curing was 1 μm, and was applied. The protective film is combined, and then ultraviolet rays as active energy rays are irradiated to harden the adhesive. Ultraviolet rays were irradiated with a gallium-encapsulated metal halide lamp. The irradiation device was Light HAMMER10 manufactured by Fusion UV Systems, Inc. The bulb was a V bulb. The peak illuminance was 1600 mW / cm ² and the cumulative exposure was 1000 / mJ / cm ² (wavelength 380 ~ 440 nm), and the illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell. Next, the amorphous PET substrate was peeled to produce a single-sided protective polarizing film using a thin polarizer. The optical properties of the obtained single-sided protective polarizing film were 42.8% for a single transmittance and 99.99% for a polarization degree.

<Production of single-sided protective polarizing film with first transparent layer> The forming material A of the first transparent layer was applied to the surface of the polarizer of the single-sided protective polarizing film with a bar coater (the protective film of the polarizer is not provided). Then, a heat treatment was performed at 60 ° C. for 12 hours to prepare and form a urethane resin layer having a thickness of 1 μm.

<Single-sided protective polarizing film with first and third transparent layers: making a polarizing film with an adhesive layer> Next, the first transparent layer formed on the single-sided protective polarizing film is bonded and formed on the release sheet. An adhesive layer (third transparent layer) with a thickness of 20 μm on the peeled surface of the material (separator), and a polarizing film with an adhesive layer was produced.

Examples 2 to 6 and Comparative Examples 1 to 9 The types of polarizers, types of protective films, forming materials of the first transparent layer, thickness, forming materials of the second transparent layer, and thickness in Example 1 were changed to the following table. As shown in FIG. 1, other than that, a single-sided protective polarizing film with a first transparent layer and a polarizing film with an adhesive layer were produced in the same manner as in Example 1. 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%.

However, in Example 4, when a single-sided protective polarizing film was produced, an adhesive layer (second transparent layer) with a thickness of 5 μm formed by the forming agent c on the release-treated surface of the release sheet (separator) was formed. ) Is bonded to the surface of the polarizer A of the optical film laminate. After that, the release sheet (separator) of the adhesive layer (second transparent layer) is peeled off, and the protective film is bonded. Next, the amorphous PET substrate was peeled to produce a single-sided protective polarizing film using a thin polarizer.

In Comparative Examples 1 and 6, the first transparent layer was not formed. The first transparent layer of Comparative Example 5 was formed 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 6 and 7, a polarizer B (thickness: 12 μm) was used instead of the polarizer A (thickness: 5 μm).

The following evaluations were performed on the polarizing film with an adhesive layer obtained in the above examples and comparative examples. 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≫ The second transparent layer forming material prepared in the examples and comparative examples was applied to aluminum foil paper with a bar coater to a thickness of 10 μm. After the second transparent layer was formed in the same manner as in Examples and Comparative Examples, 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 and third transparent layers: 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 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.

[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 the transmission axes of the two and the transmittance (orthogonal transmission) 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 film with an adhesive layer prepared in the examples and comparative examples was cut into 50 mm × 50 mm, and it was bonded to a 1.2-1.5 mm thick alkali glass (Matsuba Glass Co., Ltd. (Slides, slides) to make samples.

<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. This immobilization of heavy water sample, after removing the protective film by etching, embodiments TOF-SIMS analysis, measuring ion heavy water (D ^-) from the protective film side to the Ar gas cluster ion distribution in the depth direction, and the first acknowledgment Water gradient in transparent layer. When the water gradient was confirmed, it was evaluated as “0: there is a permeable membrane function”, and when the water gradient was not confirmed, it was evaluated as “×: no osmosis membrane function”. 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: Direction of orthogonal polarization to the transmission axis of the polarizing film

[Table 1]

P‧‧‧Polarizer

1‧‧‧ the first transparent layer

2‧‧‧ second transparent layer (adhesive layer or adhesive layer)

3‧‧‧ third transparent layer (adhesive layer)

4‧‧‧ protective film

11, 12, 13, 14‧‧‧ polarizing 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. FIG. 4 is an example of a schematic cross-sectional view of a polarizing film of the present invention.

Claims (12)

A polarizing film includes a polarizer, a first transparent layer on one side of the polarizer, and a second transparent layer on the other side of the polarizer. The polarizing film is characterized in that: the first transparent layer is The saturated moisture content at 85 ° C and 85% RH is lower than the saturated moisture content of the polarizer at 85 ° C and 85% RH. The first transparent layer is used as a permeable film to help discharge the moisture in the polarizer. Function: The saturated moisture content of the second transparent layer at 85 ° C. and 85% RH is 5% by weight or less. 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 has a third transparent layer adjacent to the side opposite to the side having the polarizer; the third transparent layer is at 85 ° C, 85% RH The saturated moisture content below is lower than the saturated moisture content of the first transparent layer at 85 ° C and 85% RH; the moisture in the polarizer sequentially penetrates the first transparent layer and the third from the polarizer side. Transparent layer. The polarizing film according to claim 8 or 9, wherein the third transparent layer is an adhesive layer. The polarizing film according to any one of claims 1 to 9, which has a protective film on the other side of the polarizer with the second transparent layer interposed therebetween. The polarizing film according to any one of claims 1 to 10, wherein the second transparent layer is an adhesive layer or an adhesive layer. An image display device having a polarizing film according to any one of claims 1 to 11.