WO2018221323A1

WO2018221323A1 - Polarizing film and image display device

Info

Publication number: WO2018221323A1
Application number: PCT/JP2018/019668
Authority: WO
Inventors: 康隆石原; 岸　敦史; 友徳上野
Original assignee: 日東電工株式会社
Priority date: 2017-06-02
Filing date: 2018-05-22
Publication date: 2018-12-06
Also published as: KR102579337B1; TW201903442A; JP6566993B2; KR20200007826A; CN110720061A; CN110720061B; JP2018205490A; TWI671556B

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 polarizing film can form an image display device such as a liquid crystal display device (LCD) or an organic EL display device alone or as an optical film obtained by laminating the polarizing film.

In a liquid crystal display device, it is indispensable to dispose polarizing films on both sides of a glass substrate that forms the surface of a liquid crystal panel because of its image forming method. In general, a polarizing film in which a protective film is bonded to one or both sides of a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine with a polyvinyl alcohol adhesive or the like is used. .

In addition, the polarizing film is exposed to a harsh environment depending on the intended use and usage state. Therefore, the polarizing film is required to have durability that can maintain optical characteristics even in a harsh environment. For example, it has been proposed to provide a urethane resin having a predetermined storage elastic modulus on at least one surface of a polarizer (Patent Documents 1 and 2). According to

Patent Documents

1 and 2, it is described that the orthogonal transmittance of the polarizing film can be maintained even at high temperatures.

Japanese Patent Laid-Open No. 11-030715 Japanese Patent Laid-Open No. 11-183726

Also, the polarizing film may be used in a high temperature and high humidity environment in addition to a high temperature environment. Under such a severe environmental atmosphere, it was found that the moisture in the environmental atmosphere affects the optical characteristics of the polarizer, and the degree of polarization is greatly reduced at the end of the polarizing film. However, by providing the polarizer with the urethane resin as in

Patent Documents

1 and 2 above, the decrease in the degree of polarization cannot be sufficiently suppressed at the end of the polarizing film.

An object of the present invention is to provide a polarizing film that can suppress a decrease in the degree of polarization at the end portion even in a high-temperature and high-humidity environment.

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

As a result of intensive studies, the inventors of the present application have found that the above-mentioned problems can be solved by the following polarizing film and the like, and have reached the present invention.

That is, the present invention is a polarizer, a polarizing film having a first transparent layer on one side of the polarizer, and a second transparent layer on the other side of the polarizer,
85 ° C., 85% R.D. of the first transparent layer. H. The saturated moisture content at 85 ° C. and 85% R.V. H. Lower than the saturated moisture content in
The first transparent layer functions as a permeable membrane that helps discharge moisture in the polarizer,
85 ° C., 85% R.D. of the second transparent layer. H. It is related with the polarizing film characterized by the saturated moisture content in being 5 weight% or less.

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

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

In the polarizing film, a cured product of a forming material containing a urethane prepolymer that is a reaction product of an isocyanate compound and a polyhydric alcohol can be used as the first transparent layer. As the isocyanate compound, it is preferable to use at least one selected from tolylene diisocyanate and diphenylmethane diisocyanate.

In the polarizing film, the first transparent layer is 85 ° C., 85% R.V. in the first transparent layer. H. It is preferable that the saturated moisture concentration in the layer has a gradient distribution that gradually decreases from the polarizer side toward the opposite side of the polarizer.

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

The polarizing film has a third transparent layer adjacent to the side of the first transparent layer opposite to the side having the polarizer,
85 ° C., 85% R.D. of the third transparent layer. H. The saturated moisture content at 85 ° C. and 85% R.S. H. Lower than the saturated moisture content in
It is preferable that moisture in the polarizer permeates in the order of the first transparent layer and the third transparent layer from the polarizer side.

In the polarizing film, an example of the third transparent layer is a pressure-sensitive adhesive layer.

In the polarizing film, the first transparent layer has only one side of the polarizer,
A protective film may be provided on the other surface of the polarizer.

In the polarizing film, the second transparent layer includes a pressure-sensitive adhesive layer or an adhesive layer.

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

Since the polarizer, which is a constituent element of the polarizing film, is formed of an aqueous material, moisture in the environmental atmosphere is easily taken into the polarizer. Therefore, it is considered that when the polarizing film is held in a high temperature and high humidity environment, the saturated moisture content in the polarizer increases. As a result, the optical properties of the polarizing film tend to be reduced. In particular, in a high-temperature and high-humidity environment, the amount of moisture entering the polarizer is large, so the degree of polarization greatly decreases at the end of the polarizing film, causing a phenomenon called end-color loss. it is conceivable that.

The polarizing film of the present invention has a first transparent layer functioning as a permeable membrane that assists the drainage of moisture in the polarizer on one side of the polarizer. The saturated moisture content of the first transparent layer in a high-temperature and high-humidity environment is designed to be lower than the saturated moisture content of the polarizer, so even if moisture in the ambient atmosphere has entered the polarizer, Can be actively transmitted to the first transparent layer (permeation membrane) side having a saturation moisture content lower than the saturation moisture content of the polarizer, and the action allows moisture in the polarizer to be removed from the polarizer. Can be discharged. On the other hand, the other surface of the polarizer has a second transparent layer having a saturated moisture content of 5% by weight or less, and the second transparent layer having a low saturated moisture content prevents moisture from entering the polarizer. While suppressing, the water | moisture-content spreading | diffusion from the said polarizer P is prevented, it can go to the 1st transparent layer (permeation membrane) side, and it can permeate | transmit the moisture content of a polarizer. Thus, the polarizing film of the present invention has the first transparent layer and the second transparent layer, so that an increase in the saturated moisture content of the polarizer can be suppressed even under a high temperature and high humidity environment. The amount of color loss at the end can be suppressed.

It is an example of the schematic sectional drawing of the polarizing film of this invention. It is an example of the schematic sectional drawing of the polarizing film of this invention. It is an example of the schematic sectional drawing of the polarizing film of this invention. It is an example of the schematic sectional drawing of the polarizing film of this invention.

Hereinafter, the polarizing film of the present invention will be described with reference to FIGS. 1 to 4.
The polarizing film of the present invention includes, for example, a polarizer P and a first transparent layer 1 (penetrating membrane: a layer having a function of helping discharge of water) like the polarizing film 11 shown in FIGS. And having. 1 to 4 exemplify a case in which the first transparent layer 1 is provided on one side of the polarizer P and the second transparent layer 2 having a saturated moisture content of 5% by weight or less is provided on the other side. ing. Further, as shown in FIGS. 1 to 4, the first transparent layer 1 is provided directly on the polarizer P to suppress an increase in the saturated moisture content of the polarizer in a high temperature and high humidity environment. It is preferable from the viewpoint of suppressing color loss at the end.

Moreover, the polarizing film of this invention can provide the 3rd transparent layer 3 further in the 1st transparent layer 1 of the said polarizing film 11 like the polarizing film 12 shown in FIG. 2, for example. The third transparent layer 3 is preferably provided directly on the first transparent layer 1 from the viewpoint of suppressing an increase in the saturated moisture content of the polarizer in a high-temperature and high-humidity environment and suppressing end color loss of the polarizing film. .

On the other hand, in the polarizing film of the present invention, a protective film 4 can be provided on the second transparent layer 2 of the polarizing film 11 like a polarizing film 13 shown in FIG. When the protective film 4 is used, moisture diffusion from the polarizer P together with the second transparent layer 2 is hindered by the protective film 4 (particularly a material having a low moisture permeability). It is preferably applied in the embodiment of the piece protective polarizing film having the protective film 4 only on one side. FIG. 4 shows a case where the 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 this invention, when using an adhesive layer as the 3rd transparent layer 3, a separator can be provided in the said 3rd transparent layer (adhesive layer). On the other hand, the polarizing films 11 to 14 of the present invention can be appropriately provided with a surface protective film.

<Polarizer>
The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 80 μm or less.

A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared, for example, by dyeing a polyvinyl alcohol film in an aqueous solution of iodine and stretching it 3 to 7 times the original length. it can. If necessary, it can be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with stains and antiblocking agents by washing the polyvinyl alcohol film with water, the polyvinyl alcohol film is also swollen to prevent unevenness such as uneven coloring. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution of 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. The thickness of the polarizer is preferably 8 μm or less from the viewpoint of thinning, more preferably 7 μm or less, and further preferably 6 μm or less. On the other hand, the thickness of the polarizer is preferably 2 μm or more, and more preferably 3 μm or more. Such a thin polarizer has little thickness unevenness, excellent visibility, and little dimensional change, and thus excellent durability against thermal shock.

As a thin polarizer, typically,
Patent No. 4751486,
Japanese Patent No. 4751481,
Patent No. 4815544,
Patent No. 5048120,
International Publication No. 2014/077599 pamphlet,
International Publication No. 2014/077636 Pamphlet,
And the thin polarizers obtained from the production methods described therein.

The polarizer has an optical characteristic expressed by a single transmittance T and a polarization degree P of the following formula P> − (10 ^0.929T-42.4 −1) × 100 (where T <42.3), Or
It is configured to satisfy the condition of P ≧ 99.9 (however, T ≧ 42.3). A polarizer configured so as to satisfy the above-described conditions uniquely has performance required as a display for a liquid crystal television using a large display element. Specifically, the contrast ratio is 1000: 1 or more and the maximum luminance is 500 cd / m ² or more. As other uses, for example, it is bonded to the viewing side of the organic EL display device.

As the thin polarizer, among the production methods including the step of stretching in the state of a laminate and the step of dyeing, Patent No. 4751486, Patent, in that it can be stretched at a high magnification and the polarization performance can be improved. What is obtained by the manufacturing method including the process of extending | stretching in a boric-acid aqueous solution as described in the 4751481 specification and the patent 4815544 specification is preferable, and it describes especially in the patent 4751481 specification and the patent 4815544 specification. What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric-acid aqueous solution which has this is preferable. These thin polarizers can be obtained by a production method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin base material in a laminated state and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching by being supported by the stretching resin substrate.

The polarizer of the present invention has an 85 ° C., 85% R.D. H. The saturated water content in is usually 10 to 40% by weight. The saturated moisture content of the polarizer may be 25% by weight or less, and may be 18% by weight or less from the viewpoint of suppressing end color loss. The saturated moisture content of the polarizer is not particularly limited as long as the saturated moisture content of the first transparent layer is lower than the saturated moisture content of the polarizer in relation to the first transparent layer.

The saturation moisture content of the polarizer of the present invention may be adjusted by any appropriate method. For example, the method of controlling by adjusting the conditions of the drying process in the manufacturing process of a polarizer is mentioned.

<First transparent layer>
The first transparent layer is a layer that functions as a permeable membrane that assists the drainage of water in the polarizer. H. The saturated water content in is designed so as to be lower than the saturated water content of the polarizer.

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, more preferably 3 to 15% by weight, from the viewpoint of the function as a permeable membrane. Is preferred. In addition, there is no problem if the difference in the saturated moisture content becomes too large, but on the other hand, if it becomes too small, a sufficient function as a permeable membrane cannot be exhibited. The saturated water content of the first transparent layer is preferably 1 to 10% by weight, more preferably 3 to 8% by weight.

The thickness of the first transparent layer is preferably 3 μm or less, more preferably 2 μm or less, and further preferably 1.5 μm or less from the viewpoint of the function as a permeable membrane, thinning of the layer, and optical reliability. It is preferable that it is 1 micrometer or less. When the first transparent layer is too thick, it has a thickness, and conversely, moisture discharge is hindered and the function as a permeable membrane may not be exhibited. On the other hand, the thickness of the first transparent layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and further preferably 0.3 μm or more from the viewpoint of ensuring the function as the osmotic membrane. preferable.

As the material for forming the first transparent layer, a material having transparency and satisfying the saturated moisture content can be used. Examples of such a material include a forming material containing a urethane prepolymer which is a reaction product of an isocyanate compound and a polyhydric alcohol.

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

Examples of the polyfunctional aromatic isocyanate compound include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 4 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, methylene bis 4-phenyl isocyanate, p-phenylene diisocyanate, and the like.

Examples of the polyfunctional alicyclic isocyanate compound include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-bisisocyanatomethylcyclohexane, isophorone diisocyanate, hydrogen Added diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated tetramethylxylylene diisocyanate, and the like.

Examples of the polyfunctional aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4 Examples include 4-trimethylhexamethylene diisocyanate.

Examples of the polyfunctional isocyanate compound include those having three or more isocyanate groups such as isocyanuric acid tris (6-inocyanate hexyl).

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl- 1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2- Examples thereof include methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol.

In the present invention, it is preferable to use a urethane structure having a rigid structure in which a cyclic structure (benzene ring, cyanurate ring, isocyanurate ring, etc.) accounts for a large proportion in the structure. For example, the polyfunctional isocyanate compound may be used alone or in combination of two or more, but an aromatic isocyanate compound is preferred from the viewpoint of adjusting the saturated moisture content. Other polyfunctional isocyanate compounds can be used in combination with aromatic isocyanate compounds. In particular, it is preferable to use at least one selected from tolylene diisocyanate and diphenylmethane diisocyanate as the isocyanate compound among aromatic isocyanate compounds.

As the urethane prepolymer, trimethylolpropane-tri-tolylene isocyanate and trimethylolpropane-tri-diphenylmethane diisocyanate are preferably used.

In addition, the urethane prepolymer having a terminal isocyanate group with a protecting group may be used. Protecting groups include oximes and lactams. In the case where the isocyanate group is protected, the protecting group is dissociated from the isocyanate group by heating, and the isocyanate group reacts.

Further, a reaction catalyst can be used to increase the reactivity of the isocyanate group. The reaction catalyst is not particularly limited, but a tin-based catalyst or an amine-based catalyst is suitable. The reaction catalyst can use 1 type (s) or 2 or more types. The amount of the reaction catalyst used is usually 5 parts by weight or less with respect to 100 parts by weight of the urethane prepolymer. When the amount of the reaction catalyst is large, the crosslinking reaction rate increases and foaming of the forming material occurs. Even if the forming material after foaming is used, sufficient adhesion cannot be obtained. Usually, when a reaction catalyst is used, it is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 4 parts by weight.

As the tin-based catalyst, both inorganic and organic catalysts can be used, but an organic catalyst is preferred. Examples of the inorganic tin-based catalyst include stannous chloride and stannic chloride. The organic tin-based catalyst is preferably one having at least one organic group such as an aliphatic group or alicyclic group having a skeleton such as a methyl group, an ethyl group, an ether group or an ester group. 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. For example, those having at least one organic group such as an alicyclic group such as quinoclidine, amidine, and diazabicycloundecene are preferable. In addition, examples of the amine catalyst include triethylamine. Examples of reaction catalysts other than the above include cobalt naphthenate and benzyltrimethylammonium hydroxide.

The urethane prepolymer is usually 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 are uniformly dissolved. Examples of the organic solvent include toluene, methyl ethyl ketone, ethyl acetate and the like. In the case of using an aqueous system, for example, alcohols such as n-butyl alcohol and isopropyl alcohol and ketones such as acetone can be blended. In the case of using an aqueous system, a dispersant is used, a urethane prepolymer, a functional group having low reactivity with isocyanate groups such as carboxylate, sulfonate, and quaternary ammonium salt, and water dispersibility such as polyethylene glycol. This can be done by introducing the components.

Examples of materials for forming the first transparent layer other than the urethane prepolymer include cyanoacrylate-based forming materials and epoxy-based forming materials.

The formation of the first transparent layer can be appropriately selected depending on the type of the forming material. For example, the first transparent layer can be formed by applying the forming material to a polarizer or a resin film and then curing. The transparent layer can be obtained as a coating layer. Usually, after the coating, it is carried out by forming a cured layer by drying at about 30 to 100 ° C., preferably at 50 to 80 ° C. for about 0.5 to 15 minutes. Furthermore, when the forming material contains an isocyanate component, annealing treatment is performed at about 30 to 100 ° C., preferably 50 to 80 ° C. for about 0.5 to 24 hours in order to promote the reaction. Can do.

The first transparent layer is 85 ° C., 85% R.V. in the first transparent layer. H. It is preferable to have a structure having a gradient distribution in which the saturated moisture concentration in the layer gradually decreases from the polarizer side toward the opposite side of the polarizer. With such a structure, the function as a permeable membrane can be more effectively exhibited.

<Second transparent layer>
The second transparent layer was 85 ° C., 85% R.D. H. In which the saturated moisture content is adjusted to 5% by weight 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 to the saturated moisture content of the second transparent layer.

Examples of the second transparent layer include intervening layers such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer) applied between the polarizer and the protective film. In addition, the easily bonding layer applied to a protective film is mentioned. In addition, an easy-adhesion layer can be provided in a protective film, or an activation process can be performed, and the said easy-adhesion layer and an adhesive bond layer can be laminated | stacked.

The material forming the second transparent layer may be a material having transparency and functioning as the intervening layer. At this time, it is desirable that the both are laminated without an air gap by an intervening layer.

The adhesive layer is formed with an adhesive. The type of the adhesive is not particularly limited, and various types can be used. The adhesive layer is not particularly limited as long as it is optically transparent. Examples of the adhesive include water-based, solvent-based, hot-melt-based, active energy ray-curable types, and the like. Or an active energy ray hardening-type adhesive agent is suitable.

Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex systems, 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 solid content.

The active energy ray curable adhesive is an adhesive that cures by an active energy ray such as an electron beam or ultraviolet rays (radical curable type, cationic curable type), for example, in an electron beam curable type or an ultraviolet curable type. Can be used. As the active energy ray curable adhesive, for example, a photo radical curable adhesive can be used. When the photo radical curable active energy ray curable adhesive is used as an ultraviolet curable adhesive, the adhesive contains a radical polymerizable compound and a photo polymerization initiator.

The adhesive coating method is appropriately selected depending on the viscosity of the adhesive and the target thickness. Examples of coating methods include reverse coaters, gravure coaters (direct, reverse and offset), bar reverse coaters, roll coaters, die coaters, bar coaters, rod coaters and the like. In addition, for coating, a method such as a dapping method can be appropriately used.

In addition, when the water-based adhesive or the like is used, the adhesive is preferably applied so that the finally formed adhesive layer has a thickness of 30 to 300 nm. The thickness of the adhesive layer is more preferably 60 to 250 nm. On the other hand, when an active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.1 to 200 μm. More preferably, it is 0.5 to 50 μm, and still 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 silicone, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins can be used alone or in combination of two or more. Moreover, you may add another additive for formation of an easily bonding layer. Specifically, a stabilizer such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat resistance stabilizer may be used.

The easy-adhesion layer is usually provided in advance on a protective film, and the easy-adhesion layer side of the protective film and the polarizer are laminated with an adhesive layer. The easy-adhesion layer is formed by applying and drying a material for forming the easy-adhesion layer on a protective film by a known technique. The material for forming the easy-adhesion layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of the thickness after drying and the smoothness of coating. The thickness of the easy-adhesion layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and still more preferably 0.05 to 1 μm. Note that a plurality of easy-adhesion layers can be provided, but also in this case, the total thickness of the easy-adhesion layers is preferably in the above range.

The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive. Various pressure-sensitive adhesives can be used as the pressure-sensitive adhesive, such as rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, polyvinylpyrrolidone-based pressure-sensitive adhesives, Examples include acrylamide-based adhesives and cellulose-based adhesives. An adhesive base polymer is selected according to the type of the adhesive. Among the pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used because they are excellent in optical transparency, exhibit appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and are excellent in weather resistance and heat resistance. The

The undercoat 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 the material exhibits 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, stretchability, etc. is used. Examples of the thermoplastic resin include an acrylic resin, a polyolefin resin, a polyester resin, a polyvinyl alcohol resin, or a mixture thereof.

<Third transparent layer>
In the polarizing film of the present invention, a third transparent layer can be further formed on the first transparent layer. As the third transparent layer, various layers can be formed, but from the viewpoint of more functioning as a permeable membrane, the third transparent layer has a saturated moisture content lower than the saturated moisture content of the first transparent layer. It is preferable to provide a layer.

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, more preferably 0.5% from the viewpoint of the function as a permeable membrane. It is preferably ˜5 wt%. Note that there is no problem if the difference becomes too large, but on the other hand, if it becomes too small, a sufficient function as a osmotic membrane cannot be exhibited. The saturated water content of the third transparent layer is preferably used in a range lower than the saturated water content of the first transparent layer, but is preferably 0.1 to 8%, more preferably 0 Those of 5 to 5% by weight are preferably used.

The thickness of the third transparent layer is about 1 to 100 μm from the viewpoint of the function as a permeable membrane. The thickness is preferably 2 to 50 μm, more preferably 2 to 40 μm, and still more preferably 5 to 35 μm.

The third transparent layer can be formed of a resin film such as a pressure-sensitive adhesive layer, an adhesive layer, a hard coat layer, or a protective film. Among these, the pressure-sensitive adhesive layer is preferable from the viewpoint of suppressing color loss at the end of the polarizing film.

For forming the pressure-sensitive adhesive layer, an appropriate pressure-sensitive adhesive can be used, and the type thereof is not particularly limited. Examples of the pressure-sensitive adhesive include a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a vinyl alkyl ether-based pressure-sensitive adhesive.

Among these pressure-sensitive adhesives, those having excellent optical transparency, suitable wettability, cohesiveness, and adhesive pressure characteristics, and excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used as one exhibiting such characteristics.

As a method for forming the pressure-sensitive adhesive layer, for example, a method in which the pressure-sensitive adhesive is applied to a release-treated separator and the like, and a polymerization solvent is dried and removed to form a pressure-sensitive adhesive layer, and then transferred to the first transparent layer, Alternatively, the pressure-sensitive adhesive is prepared by a method of applying the pressure-sensitive adhesive to the first transparent layer, drying and removing the polymerization solvent, and forming the pressure-sensitive adhesive layer on the polarizer. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

A silicone release liner is preferably used as the release-treated separator. In the step of forming the pressure-sensitive adhesive layer by applying and drying the pressure-sensitive adhesive of the present invention on such a liner, an appropriate method may be adopted as appropriate according to the purpose. Preferably, a method of heating and drying the coating film is used. 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 within the above range, an adhesive having excellent adhesive properties can be obtained.

Appropriate time can be adopted as the drying time. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

Various methods are used as a method for forming the pressure-sensitive adhesive layer. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

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

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a peeled sheet (separator) until practical use.

Examples of the constituent material of the separator include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. A thin film can be used, but a plastic film is preferably used because of its excellent surface smoothness.

The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the separator.

<Protective film>
As the material constituting the protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like can also be mentioned as examples of the polymer forming the protective film.

Since it is optional to provide the first transparent layer of the present invention on the side to which the protective film is applied, based on the polarizer, the protective film material may be moisture intrusion from the protective film side. From the viewpoint of suppressing the above, it is preferable to use a low moisture permeability acrylic polymer, polyolefin polymer or the like.

In addition, 1 or more types of arbitrary appropriate additives may be contained in the protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When content of the said thermoplastic resin in a protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

As the protective film, a retardation film, a brightness enhancement film, a diffusion film, and the like can also be used. Examples of the retardation film include those having a front retardation of 40 nm or more and / or a retardation having a thickness direction retardation of 80 nm or more. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. In the case where a retardation film is used as the protective film, the retardation film functions also as a polarizer protective film, so that the thickness can be reduced.

Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a thermoplastic resin film. The stretching temperature, stretching ratio, and the like are appropriately set depending on the retardation value, film material, and 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 handleability, and thin layer properties. In particular, it is preferably 1 to 300 μm, more preferably 5 to 200 μm, and further preferably 5 to 150 μm, particularly 20 to 100 μm.

A functional layer such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer or an antiglare layer can be provided on the surface of the protective film where the polarizer is not adhered. In addition, the hard coat layer, the antireflection layer, the antisticking layer, the diffusion layer, the antiglare layer, and other functional layers can be provided on the protective film itself, or can be provided separately from the protective film. it can.

<Surface protection film>
A surface protective film can be provided on the polarizing film of the present invention. The surface protective film usually has a base film and an adhesive layer, and protects the polarizer via the adhesive layer.

As the base film of the surface protective film, a film material having isotropic property or close to isotropic property is selected from the viewpoints of inspection property and manageability. Examples of film materials include polyester resins such as polyethylene terephthalate film, cellulose resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, and the like. Examples thereof include transparent polymers such as resins. Of these, polyester resins are preferred. The base film can be used as a laminate of one kind or two or more kinds of film materials, and a stretched product of the film can also be used. The thickness of the base film is generally 500 μm or less, preferably 10 to 200 μm.

The pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer of the surface protective film includes a (meth) acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based or a rubber-based pressure-sensitive adhesive. Can be appropriately selected and used. From the viewpoints of transparency, weather resistance, heat resistance and the like, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable. The thickness (dry film thickness) of the pressure-sensitive adhesive layer is determined according to the required adhesive force. Usually, it is about 1 to 100 μm, preferably 5 to 50 μm.

The surface protective film can be provided with a release treatment layer on the surface opposite to the surface on which the pressure-sensitive adhesive layer is provided on the base film, using a low adhesion material such as silicone treatment, long-chain alkyl treatment, or fluorine treatment. .

<Other optical layers>
The polarizing film of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film. One or more optical layers that may be used can be used. In particular, a reflective polarizing film or semi-transmissive polarizing film in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing film of the present invention, an elliptical polarizing film or circularly polarizing film in which a retardation film is further laminated on a polarizing film. A wide viewing angle polarizing film obtained by further laminating a viewing angle compensation film on a film or a polarizing film, or a polarizing film obtained by further laminating a brightness enhancement film on the polarizing film is preferred.

An optical film obtained by laminating the above optical layer on a polarizing film can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. It is excellent in stability and assembly work, and has the advantage of improving the manufacturing process of a liquid crystal display device and the like. For the lamination, an appropriate adhesive means such as a pressure-sensitive adhesive layer can be used. When adhering the above polarizing film and other optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

The polarizing film or optical film of the present invention can be preferably used for forming various image display devices such as liquid crystal display devices and organic EL display devices. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing film or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses a polarizing film or an optical film by invention, and it can apply according to the former. As the liquid crystal cell, an arbitrary type such as an IPS type or a VA type can be used, but is particularly suitable for the IPS type.

Appropriate liquid crystal display devices such as a liquid crystal display device in which a polarizing film or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the polarizing film or optical film by this invention can be installed in the one side or both sides of a liquid crystal cell. When providing a polarizing film or an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples shown below. In addition, all the parts and% in each example are based on weight. The room temperature standing conditions not specifically specified below are all 23 ° C. and 65% R.S. H. It is.

(Preparation of thin polarizer A)
One side of an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption of 0.75% and Tg of 75 ° C. is subjected to corona treatment. Alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. An aqueous solution containing 9: 1 ratio of the trade name “Gosefimer Z200”) was applied and dried at 25 ° C. to form a PVA-based resin layer having a thickness of 11 μm, thereby preparing a laminate.
The obtained laminate was uniaxially stretched in the longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (air-assisted stretching process).
Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Subsequently, it was immersed in a dyeing bath having a liquid temperature of 30 ° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was blended with 100 parts by weight of water, and immersed in an aqueous iodine solution obtained by blending 1.0 part by weight of potassium iodide (dyeing treatment). .
Subsequently, it was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (Crosslinking treatment).
Thereafter, the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ° C. However, uniaxial stretching was performed between rolls having different peripheral speeds in the longitudinal direction (longitudinal direction) so that the total stretching ratio was 5.5 times (in-water stretching treatment).
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. (cleaning treatment).
As a result, an optical film laminate including a polarizer having a thickness of 5 μm was obtained.

(Preparation of polarizer B (12 μm thick polarizer))
A polyvinyl alcohol film having an average polymerization degree of 2400 and a saponification degree of 99.9 mol% and a thickness of 30 μm 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 of 0.3% concentration of iodine / potassium iodide (weight ratio = 0.5 / 8) and stretched to 3.5 times. Then, it extended | stretched so that the total draw ratio might be 6 time in 65 degreeC borate ester aqueous solution. After stretching, drying was performed in an oven at 40 ° C. for 3 minutes to obtain a PVA polarizer. The thickness of the obtained polarizer was 12 μm.

(Protective film)
Acrylic: A (meth) acrylic resin film having a lactone ring structure with a thickness of 40 μm was subjected to corona treatment on the easy adhesion treated surface.
TAC: manufactured by Fuji Film Co., Ltd., product name “TJ40”, and a 40 μm thick triacetyl cellulose resin film was used.
COP: manufactured by Nippon Zeon Co., Ltd., product name “ZEONOR FILM”, 25 μm thick cycloolefin resin film was used.

<Forming material for first transparent layer (block layer)>
Forming material A: Dioctyltin dilaurate catalyst (trade name, manufactured by Tokyo Fine Chemical Co., Ltd.) in 100 parts of a 75% ethyl acetate solution of urethane prepolymer composed of tolylene diisocyanate and trimethylolpropane (trade name “Coronate L” manufactured by Tosoh Corporation) 0.1 parts of “Enabilizer OL-1” was added, and a urethane prepolymer coating solution was prepared with methyl isobutyl ketone as a solvent at a solid content concentration of 10%.
Forming material B: The same catalyst and solvent as the forming agent A were used except that a 75% ethyl acetate solution of urethane prepolymer composed of diphenylmethane diisocyanate and trimethylolpropane (trade name “Coronate 2067” manufactured by Tosoh Corporation) was used. Thus, a coating solution was prepared.
Forming material C: The same catalyst and solvent as the forming agent A except that a 75% ethyl acetate solution of urethane prepolymer composed of hexamethylene diisocyanate and trimethylolpropane (trade name “Coronate HL” manufactured by Tosoh Corporation) was used. A coating solution was prepared using this.
Forming material D: N-hydroxyethylacrylamide and a photopolymerization initiator (IRGACURE907, manufactured by BASF) are added to 80 parts of urethane acrylate resin (manufactured by Nippon Gosei Co., Ltd., product name “purple UV-1700”), and methyl isobutyl is used as a solvent. A urethane acrylate coating solution was prepared with ketone to a solid content concentration of 10%.
Forming material E: Urethane prepolymer composed of xylylene diisocyanate and trimethylolpropane in 50 parts of a 75% ethyl acetate solution of a urethane prepolymer composed of tolylene diisocyanate and trimethylolpropane (trade name “Coronate L” manufactured by Tosoh Corporation) 50 parts of 75% ethyl acetate solution (trade name “Takenate D110N” manufactured by Mitsui Takeda Chemical Co., Ltd.) and 0.1 part of dioctyltin dilaurate catalyst (trade name “Environizer OL-1” manufactured by Tokyo Fine Chemical Co., Ltd.) were added. A urethane prepolymer coating solution was prepared with methyl isobutyl ketone as a solvent at a solid content concentration of 35%.

<Forming material for second transparent layer (block layer)>
(Forming material a: Preparation of adhesive a)
10 parts by weight of N-hydroxyethylacrylamide, 30 parts by weight of acryloylmorpholine, 45 parts of 1,9-nonanediol diacrylate, 10 parts of an acrylic oligomer obtained by polymerizing (meth) acrylic monomer (ARUFONUP 1190, manufactured by Toagosei Co., Ltd.) Then, 3 parts of photopolymerization initiator (IRGACURE 907, manufactured by BASF) and 2 parts of polymerization initiator (KAYACURE DETX-S, manufactured by Nippon Kayaku Co., Ltd.) were mixed to prepare an ultraviolet curable adhesive.

(Forming material b: Preparation of adhesive b)
40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts of acryloylmorpholine and 3 parts by weight of a photopolymerization initiator (IRGACURE 819, manufactured by BASF) were mixed to prepare an ultraviolet curable adhesive.

(Forming agent c: Preparation of pressure-sensitive adhesive c and formation of pressure-sensitive adhesive layer)
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 100 parts of butyl acrylate, 3 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate and 2,2′-azobisisobutyrate A solution was prepared by adding 0.3 parts of ronitrile with ethyl acetate. Next, the solution was stirred while blowing nitrogen gas and reacted at 55 ° C. for 8 hours to obtain a solution containing an acrylic polymer having a weight average molecular weight of 2.2 million. Furthermore, the acrylic polymer solution which added ethyl acetate to the solution containing this acrylic polymer and adjusted solid content concentration to 30% was obtained.

As a cross-linking agent, 100 parts by weight of the solid content of the acrylic polymer solution is a cross-linking agent mainly composed of a compound having an isocyanate group of 0.5 part (trade name “Coronate L” manufactured by Nippon Polyurethane Co., Ltd.). And 0.075 parts of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KMB-403”) as a silane coupling agent in this order, Was prepared. The pressure-sensitive adhesive solution was applied to the surface of a release sheet (separator) made of a peeled polyethylene terephthalate film (thickness 38 μm) so that the thickness after drying was 5 μm and dried to form a pressure-sensitive adhesive layer. Formed.

<Formation of third transparent layer (adhesive layer)>
The pressure-sensitive adhesive solution prepared with the above-mentioned forming agent c was applied to the surface of a release sheet (separator) made of a polyethylene terephthalate film (thickness 38 μm) subjected to a release treatment so that the thickness after drying was 20 μm and dried. Thus, an adhesive layer was formed.

Example 1
<Production of single-protective polarizing film>
After applying the protective film (acrylic) to the surface of the polarizer A of the optical film laminate, while applying the ultraviolet curable adhesive a so that the thickness of the adhesive layer after curing is 1 μm. The adhesive was cured by irradiating ultraviolet rays as active energy rays. Ultraviolet irradiation is performed using a gallium-encapsulated metal halide lamp, an irradiation device: Fusion UV Systems, Inc. Light HAMMER 10, Inc., bulb: V bulb, peak illuminance: 1600 mW / cm ² , integrated irradiation amount 1000 / mJ / cm ² (wavelength 380 to 440 nm) ), And the illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell. Subsequently, the amorphous PET base material was peeled off to produce a piece protective polarizing film using a thin polarizer. The optical properties of the obtained piece-protecting polarizing film were a single transmittance of 42.8% and a degree of polarization of 99.99%.

<Preparation of a single protective polarizing film with a first transparent layer>
The first transparent layer forming material A is applied to the polarizer surface (the polarizer surface on which the protective film is not provided) of the piece protective polarizing film with a bar coater, and then heat treated at 60 ° C. for 12 hours. Then, a urethane resin layer having a thickness of 1 μm was formed.

<Strip protection polarizing film with first and third transparent layers: Production of polarizing film with pressure-sensitive adhesive layer>
Next, a 20 μm thick adhesive layer (third transparent layer) formed on the release treatment surface of the release sheet (separator) is bonded to the first transparent layer formed on the single protective polarizing film, and the adhesive layer An attached polarizing film was produced.

Examples 2-6, Comparative Examples 1-9
Example 1 except that the type of polarizer, the type of protective film, the forming material of the first transparent layer, the thickness, the forming material of the second transparent layer, and the thickness were changed as shown in Table 1. In the same manner as above, a piece protective polarizing film with a first transparent layer and a polarizing film with a pressure-sensitive adhesive layer were produced. The optical properties of the obtained piece-protecting polarizing film were as follows: the transmittance was 42.8% and the degree of polarization was 99.99%.

However, in Example 4, in the production of the one-piece protective polarizing film, the thickness of 5 μm formed on the surface of the polarizer A of the optical film laminate by the forming agent c on the release treatment surface of the release sheet (separator). An adhesive layer (second transparent layer) was bonded. Thereafter, the release sheet (separator) of the pressure-sensitive adhesive layer (second transparent layer) was peeled off, and the protective film was bonded. Subsequently, the amorphous PET base material was peeled off to produce a piece 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 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 rays having an integrated light quantity of 300 mJ / cm ² with a high-pressure mercury lamp to form a 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 evaluation was performed on the polarizing film with the pressure-sensitive adhesive layer obtained in the above Examples and Comparative Examples. The results are shown in Table 1.

<Measurement of saturated moisture content of polarizer>
Before the polarizers prepared in Examples and Comparative Examples were bonded together, they were taken out alone and a sample of about 50 mg was collected. The sample was subjected to 85 ° C. 0% R.D. using a moisture adsorption / desorption measuring device (IGA-Sorp, manufactured by Hiden). H. The weight (W1) in a state in which moisture was completely removed by leaving it until the weight change disappeared under the environment of the H. The sample was allowed to stand in the environment of and observed for changes in weight. When there was no change in the weight of the sample (saturated state), its weight (W2) was measured. The saturated moisture content was measured from the following formula.

<Measurement of saturated moisture content of first transparent layer>
After forming the first transparent layer in the same manner as in the examples and comparative examples, except that the first transparent layer forming material prepared in the examples and comparative examples was applied to the aluminum foil to a thickness of 10 μm by a bar coater. A sample was cut out to a size of 10 × 10 mm. The sample was subjected to 85 ° C. 0% R.D. using a moisture adsorption / desorption measuring device (IGA-Sorp, manufactured by Hiden). H. The weight (W1) in a state in which moisture was completely removed by leaving it until the weight change disappeared under the environment of the H. The sample was allowed to stand in the environment of and observed for changes in weight. When there was no change in the weight of the sample (saturated state), its weight (W2) was measured. An aluminum foil having the same size was cut out from each weight, and the saturated moisture content was measured by the following formula, except for the weight of the aluminum foil that had been measured in advance.

≪Second transparent layer: Adhesive layer≫
After forming the second transparent layer in the same manner as in the examples and comparative examples except that the second transparent layer forming material prepared in the examples and comparative examples was applied to the aluminum foil to a thickness of 10 μm by a bar coater. A sample was cut out to a size of 10 × 10 mm. The sample was subjected to 85 ° C. 0% R.D. using a moisture adsorption / desorption measuring device (IGA-Sorp, manufactured by Hiden). H. The weight (W1) in a state in which moisture was completely removed by leaving it until the weight change disappeared under the environment of the H. The sample was allowed to stand in the environment of and observed for changes in weight. When there was no change in the weight of the sample (saturated state), its weight (W2) was measured. An aluminum foil having the same size was cut out from each weight, and the saturated moisture content was measured by the following formula, except for the weight of the aluminum foil that had been measured in advance.

«Second and third transparent layers: adhesive layer»
About 50 mg of a sample was collected from the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer produced in Examples and Comparative Examples. The sample was subjected to 85 ° C. 0% R.D. using a moisture adsorption / desorption measuring device (IGA-Sorp, manufactured by Hiden). H. The weight (W1) in a state in which moisture was completely removed by leaving it until the weight change disappeared under the environment of the H. The sample was allowed to stand in the environment of and observed for changes in weight. When there was no change in the weight of the sample (saturated state), its weight (W2) was measured.

<Single transmittance T and polarization degree P of polarizer>
The single transmittance T and polarization degree P of the obtained piece-protecting polarizing film were measured using a spectral transmittance measuring device with an integrating sphere (Dot-3c, Murakami Color Research Laboratory).
The degree of polarization P is the transmittance when two identical polarizing films are overlapped so that their transmission axes are parallel (parallel transmittance: Tp), and overlapped so that their transmission axes are orthogonal to each other. It is calculated | required by applying the transmittance | permeability (orthogonal transmittance | permeability: Tc) at the time of combining to the following formula | equation. Polarization degree P (%) = {(Tp−Tc) / (Tp + Tc)} ^1/2 × 100
Each transmittance is represented by a Y value obtained by correcting visibility with a two-degree field of view (C light source) of JIS Z8701, with 100% of the completely polarized light obtained through the Granteller prism polarizer.

(Preparation of evaluation sample)
Samples obtained by cutting the polarizing film with the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples into 50 mm × 50 mm, and bonding them to 1.2 to 1.5 mm thick alkali glass (manufactured by Matsunami Glass Co., Ltd., micro slide glass). Was made.

<Confirmation of moisture gradient in the first transparent layer>
Fill the container with a sufficient amount of heavy water that does not volatilize during the test, seal the container, hold the container in a high-temperature environment at 80 ° C for 500 hours, and immediately after removal, -100 ° C or less A sample in which heavy water ions were immobilized was obtained by instant freezing. This heavy water fixed sample is etched with Ar gas cluster ions from the protective film side to remove the protective film, and then subjected to TOF-SIMS analysis to measure the distribution of heavy water ions (D ⁻ ) in the depth direction. The moisture gradient in the first transparent layer was confirmed. The case where the moisture gradient was confirmed was rated as “◯: osmotic membrane function”, and the case where the moisture gradient was not confirmed was marked as “X: osmotic membrane function”.
Equipment: ULVAC-PHI, TRIFT-V
Etching ion: Ar gas cluster ion irradiation Primary ion: Bi ₃ ²⁺
Primary ion acceleration voltage: 30 kV
Measuring electrode: Negative ion Measuring temperature: -100 ° C or less Measuring area: 100μm square

<Durability>
The above sample was treated at 85 ° C. and 85% H. After being kept in a high-temperature and high-humidity environment for 500 hours and then allowed to stand at room temperature (23 ° C., 65% RH), the amount of color loss at the end was measured using a differential interference microscope (Olympus, product name “MX-61L”). The measurement was performed under the following conditions. The color loss at the end is the distance between the straight line connecting the corner and the closest part to the center of the four corners of the sample where the color is lighter than the center. The average value of the four corners was defined as the end color loss amount of the sample.
Device: Olympus MX-61L
Measurement conditions Lens magnification: 5 times ISO: 200
Shutter speed: 1/100
Reflected light quantity: Scale 0
White balance: Auto transmitted light controller: LG-PS2
Transmitted light quantity: Scale 5
Transmitted light polarization direction: Direction of crossed Nicols with respect to the polarizing film transmission axis

P Polarizer 1 First transparent layer 2 Second transparent layer (adhesive layer or adhesive layer)
3 Third transparent layer (adhesive layer)
4 Protective film

Claims

A polarizer, a polarizing film having a first transparent layer on one side of the polarizer and a second transparent layer on the other side of the polarizer,
85 ° C., 85% R.D. of the first transparent layer. H. The saturated moisture content at 85 ° C. and 85% R.V. H. Lower than the saturated moisture content in
The first transparent layer functions as a permeable membrane that helps discharge moisture in the polarizer,
85 ° C., 85% R.D. of the second transparent layer. H. A polarizing film having a saturated moisture content of 5% by weight or less.
The polarizing film according to claim 1, wherein the first transparent layer is directly formed on a polarizer.
The polarizing film according to claim 1 or 2, wherein the first transparent layer has a thickness of 3 µm or less.
The polarizing film according to any one of claims 1 to 3, wherein the first transparent layer is a cured product of a forming material containing a urethane prepolymer that is a reaction product of an isocyanate compound and a polyhydric alcohol. .
The polarizing film according to claim 4, wherein the isocyanate compound contains at least one selected from tolylene diisocyanate and diphenylmethane diisocyanate.
The first transparent layer is 85 ° C., 85% R.V. in the first transparent layer. H. 6. The polarizing film according to claim 1, wherein the polarizing film has a gradient distribution such that the saturated moisture concentration in the film gradually decreases from the polarizer side toward the opposite side of the polarizer.
The polarizing film according to claim 1, wherein the polarizer has a thickness of 10 μm or less.
In the first transparent layer, on the side opposite to the side having the polarizer, a third transparent layer is provided adjacently,
85 ° C., 85% R.D. of the third transparent layer. H. The saturated moisture content at 85 ° C. and 85% R.S. H. Lower than the saturated moisture content in
The polarizing film according to any one of claims 1 to 7, wherein moisture in the polarizer permeates in the order of the first transparent layer and the third transparent layer from the polarizer side.
The polarizing film according to claim 8 or 9, wherein the third transparent layer is an adhesive layer.
10. The polarizing film according to claim 1, wherein a protective film is provided on the other surface of the polarizer via the second transparent layer.
11. The polarizing film according to claim 1, wherein the second transparent layer is a pressure-sensitive adhesive layer or an adhesive layer.
An image display device comprising the polarizing film according to any one of claims 1 to 11.