JP2008070571A - High durable polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate having small degradation in polarization characteristics and causing no change in color in a wet heat durability test and a dry heat durability test. <P>SOLUTION: The polarizing plate provided with at least one or more layers formed by curing a high polymerizable resin composition on a polarizing element film formed by treating a hydrophilic high polymer adsorbing a dichroic dye and boric acid with a solution having pH of 1.0-6.0 has durability, particularly remarkably improved wet heat durability and does not cause the change in color even in a dry heat durable state. The polarizing plate having high transmittance, high contrast and high durability is obtained as the polarizing plate for liquid crystal display. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarizing plate with improved durability.

  In general, a polarizing element film is produced by adsorbing and orienting iodine or dichroic dye, which is a dichroic dye, onto a polyvinyl alcohol resin film (hereinafter referred to as a PVA film). A protective film made of triacetyl cellulose or the like is bonded to at least one surface of this polarizing element film via an adhesive layer to form a polarizing plate, which is used for a liquid crystal display device or the like. A polarizing plate using iodine as a dichroic dye is called an iodine polarizing plate, while a polarizing plate using a dichroic dye as a dichroic dye is called a dye polarizing plate. Among these, iodine-based polarizing plates are widely used for general liquid crystal monitors, liquid crystal televisions, mobile phones, PDAs and the like because they exhibit higher transmittance and higher degree of polarization, that is, higher contrast than dye-based polarizing plates. It has been. However, although iodine-based polarizing plates are superior to dye-based polarizing plates in terms of optical properties, they are greatly inferior to dye-based polarizing plates in terms of optical durability. For example, iodine-based polarizing plates are left under high temperature and high humidity. As a result, problems such as large decolorization and a decrease in the degree of polarization occurred. Moreover, even if it is a dye-type polarizing plate, the optical characteristic does not change at all in a wet heat test, and the further high durability is desired.

JP-A-8-5836 JP 2001-272534 A JP2004-12578 JP 2001-166139 A JP2003-185842 JP-A-2004-77579 UV curing system, issued by the Technical Center, Kato Kiyomi, P259-303

  There is a demand for a polarizing plate having high transmittance and degree of polarization, high contrast, and excellent heat and humidity resistance. As an invention for this request, as described in Patent Document 1 and Patent Document 2, an improvement method using a protective film of an iodine-based polarizing plate, or a protective film of triacetyl cellulose as in Patent Document 3 and Patent Document 4 It is described that dry heat durability and wet heat durability can be improved by a method of modifying an adhesive when adhering. As described above, there is a technique in which the durability of the polarizing plate is improved by the protective film or the adhesive. However, it is not yet sufficient, and an improvement in wet heat durability of an inexpensive and simple polarizing plate is desired.

  Furthermore, as a prescription for improving the durability of a polarizing plate, there are patents for polarizing plates having a protective layer formed of an energy beam polymerizable compound on one side of a polarizer as in Patent Documents 5 and 6. However, just having a protective layer formed of an energy beam polymerizable compound on one side of the polarizer as in the prescription of Patent Document 5 or Patent Document 6 is insufficient in wet heat durability, and the film thickness of the protective layer In some cases, the uncured monomer of the polymerizable compound increases, and conversely, the wet heat durability and the dry heat durability are lowered, and the adhesion is insufficient. In addition, there is a polarizing plate having a resin hardened layer such as a hard coat layer, which is a well-known technique. However, simply providing a resin layer such as a hard coat does not necessarily improve wet heat durability to a high degree, In the heat durability test, the plate was severely deteriorated and further changed in color.

  As a result of intensive studies to solve the above-mentioned problems, a polarizing element film obtained by treating a hydrophilic polymer stretched by adsorbing a dichroic dye and boric acid with a solution having a pH of 1.0 to 6.0 The polarizing plate is characterized in that the polarizing element film is provided with at least one layer obtained by curing the polymerizable resin composition, and the durability, mainly wet heat durability, is greatly improved. And it discovered newly that the polarizing plate which a color change does not occur also in dry heat durability was obtained.

That is, the present invention
(1) A polarizing plate using a polarizing element film obtained by treating a hydrophilic polymer film drawn by adsorbing dichroic dye and boric acid with a solution having a pH of 1.0 to 6.0. A polarizing plate comprising at least one layer obtained by curing the polymerizable resin composition on the polarizing plate,
(2) The polarizing plate according to (1), wherein the thickness of the layer obtained by curing the polymerizable resin composition is 0.5 μm to 10 μm,
(3) The polarizing plate according to (1) or (2), comprising one or more polymerizable resin compositions and one or more protective layers on both surfaces or at least one surface of the polarizing element film,
(4) The moisture permeability of the resin film layer when the polymerizable resin composition is a (meth) acrylate compound having two or more (meth) acryloyl groups and is a cured resin film layer having a thickness of 5 μm. It contains at least one (meth) acrylate compound (A) and a polymerization initiator (C) that are 1500 g / m ² or less in 24 hours, or the solubility in (A) and water at 25 ° C. is 1% by weight or less. Any one of (1) to (3), which is a polymerizable resin composition containing at least one (meth) acrylate compound (B) and a polymerization initiator (C). The polarizing plate described,
(5) The (meth) acrylate compound (B) is a (meth) acrylate compound (a) having at least one hydroxyl group and at least one (meth) acryloyl group in the molecule. And the polarizing plate according to (4),
(6) The (meth) acrylate compound (B) is a (meth) acrylate compound (b) having a dicyclopentadiene skeleton and having at least one (meth) acryloyl group (4) ) Polarizing plate,
(7) The compound (b) having a dicyclopentadiene skeleton of the (meth) acrylate compound (B) is a compound having a dicyclopentanyl skeleton or a dicyclopentenyl skeleton and a (meth) acryloyl group (6) The polarizing plate according to
(8) The (meth) acrylate compound (B) has a dicyclopentadiene skeleton and a (meth) acrylate compound (a) having one or more hydroxyl groups and one or more (meth) acryloyl groups. And (meth) acrylate compound (b) having at least one (meth) acryloyl group, and the weight ratio of (meth) acrylate compound (a) and (b) is from 5: 9 to The polarizing plate according to any one of (1) to (7), comprising a polymerizable resin composition that is 11: 3,
(9) The (meth) acrylate compound (A) is a compound having any one of a pentaerythritol skeleton, a neopentyl glycol skeleton, and a trimethylolpropane skeleton, and a (meth) acryloyl group. ), The polarizing plate according to any one of
(10) In 100 parts by weight of the polymerizable resin composition excluding the solvent, 30 to 96 parts by weight of at least one or more (meth) acrylate compounds (A) and at least one or more of ((A) above ( It has a layer obtained by curing a polymerizable resin composition containing 0 to 60 parts by weight of the (meth) acrylate compound (B) and 2 to 10 parts by weight of the polymerization initiator (C), and the thickness of the layer At least one layer having a thickness of 0.5 to 10 μm is provided, wherein the polarizing plate according to any one of (1) to (9),
(11) The (meth) acrylate compound (A) or (B) has three or more (meth) acryloyl groups, and at least one of the compounds is in 100 parts by weight of the polymerizable resin composition excluding the solvent. (1) thru | or the polarizing plate as described in any one of (10) which has a layer which hardened | cured polymeric resin composition characterized by containing 50 weight part or more in this,
(12) In the polarizing plate in which the layer obtained by curing the polymerizable resin composition is composed of a protective layer / adhesive layer / polarizing element film / adhesive layer / protective layer, at least one layer between the protective layer and the polarizing element film The polarizing plate according to any one of (1) to (11), wherein the polarizing plate is provided as described above,
(13) A layer obtained by curing the polymerizable resin composition is constituted by a protective layer (L) / adhesive layer (L) / polarizing element film / adhesive layer (M) / protective layer (M) / adhesive layer. The polarizing plate according to any one of (1) to (12), wherein at least one layer is provided between the protective layer (L) and the polarizing element film.
(14) In a polarizing plate constituted by a protective layer (L) / adhesive layer (L) / polarizing element film / adhesive layer (M) / protective layer (M) / adhesive layer, a polymerizable resin composition is used. At least one or more layers were provided between the protective layer (L) and the adhesive layer (L), between the protective layer (M) and the adhesive layer (M). The polarizing plate according to any one of (1) to (13),
(15) The polarizing plate according to any one of (1) to (14), wherein the polymerizable resin composition is an ultraviolet curable resin composition,
(16) The polarizing plate according to any one of (1) to (15), wherein the protective layer is triacetylcellulose,
(17) The polarizing plate according to any one of (1) to (16), wherein the dichroic dye is iodine,
(18) Adsorbing dichroic dye and boric acid when manufacturing a polarizing plate provided with at least one layer obtained by curing a polymerizable resin composition having a layer thickness of 0.5 μm to 10 μm The method for producing a polarizing plate according to claim 1, wherein the oriented hydrophilic polymer film is treated with a solution having a pH of 1.0 to 6.0.
About.

  The obtained polarizing plate is a polarizing plate with little change in transmittance and lowering of the degree of polarization at a temperature of 65 ° C. and a relative humidity of 93% in a wet and heat environment. A polarizing plate with little decrease in polarization degree. Further, in a dry heat environment, for example, at 90 ° C., the polarizing plate does not show discoloration due to dry heat durability. A polarizing plate having high transmittance, high contrast, and high durability in a polarizing plate for display can be obtained.

Hereinafter, the present invention will be described in detail.
In the present invention, a hydrophilic polymer film (hereinafter referred to as a polarizing element film) stretched by adsorbing dichroic dye and boric acid is treated with a solution having a pH of 1.0 to 6.0. A polarizing plate comprising a polarizing element film, wherein the polarizing element film is provided with at least one layer obtained by curing a polymerizable resin composition, and has a greatly improved durability, and The resin layer has the characteristic that no discoloration occurs due to heat or humidity.

  Examples of the resin that becomes the hydrophilic polymer film used for the polarizing element film include polyvinyl alcohol resins, amylose resins, starch resins, cellulose resins, and polyacrylate resins. A film formed by casting or the like is used. The polarizing element film may be a uniaxially stretched film by adsorbing a dichroic material such as iodine or a dichroic dye, or a polyene-based oriented film such as a dehydrated PVA film or a dehydrochlorinated polyvinyl chloride. . Among these, a PVA film and a polarizing element film made of a dichroic material such as iodine are preferable. The thickness of these polarizing elements is not particularly limited, but is generally about 5 to 80 μm.

  The manufacturing method of the PVA film which comprises a polarizing element film is not specifically limited, It can produce by a well-known method. As a production method, for example, it can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The saponification degree of the PVA film is usually preferably from 85 to 100 mol%, more preferably 95 mol% or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. Moreover, 1,000-10,000 are preferable normally and the polymerization degree of polyvinyl alcohol-type resin has more preferable 1,500-5,000. What formed the polyvinyl alcohol-type resin into a film is used as a PVA film.

  A PVA film is dyed with a dichroic substance such as iodine and uniaxially stretched to produce a polarizing element film. As a production method, for example, the PVA film can be dyed by immersing it in an aqueous solution of iodine and can be produced by stretching it 2 to 7 times the original length. You may immerse in aqueous solutions, such as a boric acid and potassium iodide, as needed. Further, if necessary, the PVA film may be immersed in water and washed before dyeing. By washing the PVA film with water, it is possible to remove dirt and plasticizers on the surface of the PVA film, and also to prevent unevenness such as uneven coloring by swelling the PVA film. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed with dyeing after iodine. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

  In addition to the dichroic dye, the PVA film is a boron compound such as boric acid, borax or ammonium borate, glyoxal or glutaraldehyde, polyvalent aldehyde such as dialdehyde starch, biuret type, isocyanurate type or block type, etc. Polyisocyanate compounds, titanium compounds such as titanium oxysulfate, ethylene glycol glycidyl ether, polyamide epichlorohydrin, succinic peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether or glycerin di You may contain the at least 1 or more types of crosslinking agent of glycidyl ether, or a water-proofing agent. For example, the appropriate concentration of boric acid is preferably 10 to 33% by weight, preferably 18 to 30% by weight, and more preferably 20 to 26% by weight with respect to the weight% of the PVA film.

  The PVA film may contain an alkali metal, an alkaline earth metal, a halide, or an inorganic metal. Substances to be treated include, for example, potassium iodide, sodium iodide, ammonium iodide, cobalt iodide, zinc iodide, zinc chloride, potassium chloride, sodium chloride, zinc fluoride tetrahydrate, aluminum chloride, fluoride. Aluminum fluoride, ammonium fluoride, potassium fluoride, potassium fluoride fluoride, titanium titanium fluoride, calcium fluoride, chromium fluoride trihydrate, potassium zirconium fluoride, ammonium hydrogen fluoride, sodium hydrogen fluoride, fluoride Examples include potassium hydrogen, hydrofluoric acid, tin fluoride, strontium fluoride, cesium fluoride, lead fluoride, barium fluoride, magnesium fluoride, lanthanum ammonium chloride, or magnesium chloride, but are particularly limited. It is not a thing. One or more kinds of halogen ions or inorganic metal ions contained in the substances shown above may be contained.

  In the present invention, a polarizing element film having high durability is obtained by treating the polarizing element film with an acidic aqueous solution having a pH of 1.0 or more and 6.0 or less. As a method of treating with the aqueous solution, the treatment is performed by immersing the polyvinyl alcohol film in the aqueous solution in the polarizing element film production step and immersing or applying the acidic aqueous solution in the acidic aqueous solution. The pH of the solution to be treated is preferably 1.0 or more and 6.0 or less. The pH of the solution is preferably 2.0 or more and 5.0 or less, more preferably 2.2 or more and 4.5 or less.

  Furthermore, in order to obtain a polarizing plate having high durability, when the PVA film adsorbing and orienting the dichroic dye and adsorbing boric acid is treated with a solution, the solution does not contain boric acid, Further, by treating with a solution containing an acidic substance and having a pH of 1.0 to 6.0, wet heat durability can be further improved, and red color change can be suppressed in the dry heat test. Acidic substances that are not boric acid are, for example, liquid acidic substances such as sulfuric acid, hydrochloric acid or nitric acid, or solid acidic substances such as zinc sulfate, aluminum sulfate, aluminum nitrate or aluminum chloride, as well as acetic acid, formic acid and citric acid. , An acidic substance which is an organic substance such as oxalic acid, tartaric acid or malic acid. In view of environmental and safety aspects, food additives such as acetic acid, citric acid, oxalic acid, tartaric acid or malic acid are preferred. These acidic substances are dissolved in a solution not containing boric acid, and the polarizing element film is treated with the solution to obtain a polarizing element film treated with an acidic substance other than boric acid. As a method for treating the acidic substance, the PVA film treated with a dichroic dye and a crosslinking agent is dissolved in an aqueous solution, and the treatment is performed by immersing the acidic substance in an acidic aqueous solution or applying an acidic aqueous solution. The pH of the solution containing the acidic substance may be 1.0 to 6.0, preferably 2.0 to 5.0, more preferably 2.2 to 4.5.

  Specifically, the process of treating with such a pH adjusted solution includes a process of swelling a PVA film, a process of adsorbing iodine, a process of adsorbing boric acid, a process of stretching, a post-treatment process after stretching, an adhesive. The process of apply | coating is mentioned. It is a post-treatment step after stretching that the wet heat durability and the dry heat durability are improved, and it is preferable to apply the drying treatment immediately after the treatment with the solution adjusted in pH.

  As described above, the durability is improved by providing a polarizing plate using the obtained polarizing element film with a layer obtained by curing the polymerizable resin composition. As the polymerizable resin composition, for example, a compound having a (meth) acryloyl group is preferably used.

  The compound having a (meth) acryloyl group is a compound as shown in Non-Patent Document 1, for example. However, the present invention is not limited to Non-Patent Document 1, and a compound having a known (meth) acryloyl group can be used. A polymerizable resin composition is prepared using these compounds and a polymerization initiator.

Furthermore, in the present invention, even in the case of a compound having a (meth) acryloyl group, in the compound (A) having two or more (meth) acryloyl groups, the resin has a thickness of 5 μm after curing. A film layer is formed, and the resin film layer is characterized in that the moisture permeability based on JIS-Z0208 is 1500 g / m ² or less in 24 hours. More preferably, the moisture permeability is 1100 g / m ² or less in 24 hours, more preferably 900 g / m ² or less in 24 hours, and more preferably 800 g / m ² or less in 24 hours. It is preferable.

  The method for evaluating the moisture permeability is a compound having a (meth) acryloyl group on a semi-bleached kraft paper (obtained from Totsuya Echo Co., Ltd.) coated with polyvinyl alcohol having a solid content concentration of 5% by weight to a thickness of 1 μm. Apply. The compound having a (meth) acryloyl group is mixed with 10 parts by weight of a resin having a (meth) acryloyl group, 5 parts by weight of toluene, and 0.6 parts by weight of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 manufactured by Ciba Specialty Chemicals). And it was set as the composition. The composition was applied to the semi-bleached kraft paper to which polyvinyl alcohol was anchor-coated so that the resin solid content after solvent evaporation would be 5 μm thick. The moisture permeability of the paper was measured based on JIS-Z0208.

この結果から、ジエチレングリコールジアクリレート、ならびにポリエチレングリコール４００ジアクリレートなどは透湿度が高い。 Table 1 shows the moisture permeability of the coating film made of the compound having a (meth) acryloyl group obtained by the above method.

Table 1 Moisture permeability when a compound having a (meth) acryloyl group is used as a coating film

From this result, diethylene glycol diacrylate and polyethylene glycol 400 diacrylate have high moisture permeability.

The wet heat durability is improved by using a compound having low moisture permeability when the coating film shown in Table 1 is used. However, in a compound that cures, sufficient hardness, adhesion, and durability of the polarizing plate cannot be further improved simply by forming a layer. In order to improve the durability, at least one (meth) acrylate compound (A) having two or more (meth) acryloyl groups having a moisture permeability of not more than 1500 g / m ^{2 in} 24 hours when the coating film is formed is used. ), And a polymerizable resin composition comprising at least one (meth) acrylate compound (B) having a solubility in water of 25 ° C. of 1% by weight or less and a polymerization initiator (C). It is good to be. The content thereof is 30 to 98 parts by weight of at least one (meth) acrylate compound (A) and 1 to 60 of (meth) acrylate compound (B) in 100 parts by weight of the polymerizable resin composition excluding the solvent. It is preferable to contain 0.1 to 10 parts by weight of a polymerization initiator (C).

  The (meth) acrylate compound (B) having a solubility in water of 25 ° C. of 1% by weight or less is more preferable as the solubility of the (meth) acrylate compound in water is lower. As a method for confirming the solubility of the (meth) acrylate compound in water at 25 ° C., the solubility when the (meth) acrylate compound in 100 g of distilled water at 25 ° C. is mixed may be confirmed. The (meth) acrylate compound having a solubility in water of 1% by weight or less corresponds to the (meth) acrylate compound (B) used in the present invention. When the solubility of the (meth) acrylate compound in water is high, that is, when the hydrophilicity is strong, the water absorption rate of the layer obtained by the polymerizable resin composition is high, leading to improvement in adhesion and optical durability. Absent. Moreover, according to this method, even if it is a (meth) acrylate compound with only one (meth) acryloyl group which cannot measure the moisture permeability of Table 1, solubility can be measured and it is useful as a parameter.

表２から分かるように、ブタンジオールモノアクリレート、N,N-ジメチルアミノエチルアクリレート、N,N-ジメチルアミノエチルメタクリレート、２−エトキシエチルアクリレート、２−ヒドロキシエチルアクリレート、２−ヒドロキシエチルメタクリレート、ヒドロキシプロピルアクリレート、２−メトキシエチルアクリレート、ビニルアセテート、N-ビニルカプロラクタム、N-ビニルピロリドン、ポリエチレングリコール４００ジアクリレート又はポリエチレングリコール２００ジアクリレートの２５℃の水に対する溶解度は１重量％以上である。これらのような（メタ）アクリレート化合物を用いてしまうと、硬度、密着性、偏光板の耐久性を向上するには至らない。 It can be confirmed from Table 2 below whether the compound does not correspond to the (meth) acrylate compound (B) whose solubility in water at 25 ° C. is 1% by weight or less.

Table 2 Solubility of compounds having a (meth) acryloyl group (g / 100 ml water)

As can be seen from Table 2, butanediol monoacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, 2-ethoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl The solubility of acrylate, 2-methoxyethyl acrylate, vinyl acetate, N-vinylcaprolactam, N-vinylpyrrolidone, polyethylene glycol 400 diacrylate or polyethylene glycol 200 diacrylate in water at 25 ° C. is 1% by weight or more. If such (meth) acrylate compounds are used, the hardness, adhesion, and durability of the polarizing plate cannot be improved.

  Further, in the (meth) acrylate compound (B), in order to further improve the hardness, adhesion, and durability of the polarizing plate, the molecule has at least one hydroxyl group and one (meth) acryloyl group. The (meth) acrylate compound (a) having at least one or the (meth) acrylate compound (b) having at least one dicyclopentadiene group and having at least one (meth) acryloyl group is used. good. The (meth) acrylate compound (B) may have at least one (meth) acryloyl group. The durability of the compound having a hydroxyl group in the molecule is improved even if at least one compound is contained in 100 parts by weight of the polymerizable resin composition, but preferably 10 to 60 parts by weight, More preferably, it may contain 20 to 60 parts by weight, more preferably 30 to 60 parts by weight.

  As the (meth) acrylate compound (a) having at least one hydroxyl group and at least one (meth) acryloyl group in the molecule, EHC-modified butyl acrylate (Denacol DA-151 manufactured by Nagase Sangyo Co., Ltd.), Glycerol methacrylate (Blenmer GLM manufactured by NOF Corporation), 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride (Blenmer QA manufactured by NOF Corporation), EO-modified phosphoric acid acrylate (Light Ester PA manufactured by Kyoeisha Oil Company), EO-modified phthalic acid acrylate (Biscoat 2308, manufactured by Osaka Organic Chemicals Co., Ltd.), EO, PO-modified phthalic acid methacrylate (Light Ester HO, manufactured by Kyoeisha Yushi Co., Ltd.), acrylated isocyanurate (Aronix M-215, manufactured by Toagosei Co., Ltd.) Kayrad made by Yakuhin R-115), dipentaerythritol monohydroxypentaacrylate (SR-399 manufactured by Sartomer), glycerol dimethacrylate (Denacol DM-811 manufactured by Nagase Sangyo Co., Ltd.), glycerol acrylate (Blenmer GAM manufactured by NOF Corporation), glycerol dimethacrylate ( Nippon Oil & Fat Co., Ltd. (Blenmer GMR), ECH-modified glycerol triacrylate (Nagase Sangyo Co., Ltd. Denacol DA-314), ECH-modified 1,6-hexanediol diacrylate (Nippon Kayaku Co., Ltd. Kayarad R-167), pentaerythritol triacrylate (Kayarad PET-30 manufactured by Nippon Kayaku Co., Ltd.), stearic acid-modified pentaerythritol diacrylate (Aronix M-233 manufactured by Toagosei Co., Ltd.), ECH-modified phthalic acid diacrylate (Denacol DA-721 manufactured by Nagase Sangyo Co., Ltd.), tri Glycerol diacrylate (Kyoei) Epoxy ester 80 MFA, manufactured by Yushi Co., Ltd.).

  Examples of the compound (b) having a dicyclopentadiene skeleton include resins having a dicyclopentanyl skeleton, a dicyclopentenyl skeleton, and an adamantane skeleton. Among them, a compound having a dicyclopentanyl skeleton or a dicyclopentenyl skeleton is preferable in order to further improve the wet heat durability. The durability of the compound having a dicyclopentadiene skeleton is improved even if at least one kind is contained in 100 parts by weight of the polymerizable resin composition, but preferably 10 to 60 parts by weight, More preferably, it may contain 15 to 40 parts by weight, more preferably 20 to 40 parts by weight.

  Examples of the compound having the dicyclopentanyl compound include dicyclopentanyl acrylate (FA-513A manufactured by Hitachi Chemical Co., Ltd.), dicyclopentanyl methacrylate (FA-513M manufactured by Hitachi Chemical Co., Ltd.), or dicyclopentanyl diacrylate. (Kayarad R-684 manufactured by Nippon Kayaku Co., Ltd.) is good. A resin having a dicyclopentanyl skeleton is most preferable.

  Examples of the compound having a dicyclopentenyl skeleton include dicyclopentenyl acrylate (FA-511A manufactured by Hitachi Chemical Co., Ltd.), dicyclopentenyloxyethyl acrylate (FA-512A manufactured by Hitachi Chemical Co., Ltd.) or dicyclopentenyloxyethyl methacrylate ( Hitachi Chemical FA-512M).

  Examples of the compound having an adamantane skeleton include 2-methyl-2-adamantyl methacrylate (Adamantate MM manufactured by Idemitsu Kosan Co., Ltd.), 2-ethyl-2-adamantyl methacrylate (Adamantate EM manufactured by Idemitsu Kosan Co., Ltd.), 3-hydroxy-1-adamantyl methacrylate ( Adamantate HM manufactured by Idemitsu Kosan Co., Ltd., 3-hydroxy-1-adamantyl acrylate (Adamantate HA manufactured by Idemitsu Kosan Co., Ltd.), 2-methyl-2-adamantyl acrylate (Adamantate MA manufactured by Idemitsu Kosan Co., Ltd.) or 2-ethyl-2-adamantyl acrylate (Idemitsu Kosan Co., Ltd.) Adamantate EA) is good.

  Among the (meth) acrylate compounds, there are resins that become (meth) acrylate compounds (A) and (meth) acrylate compounds (B). A compound satisfying both of these properties may be used as a (meth) acrylate compound (A) or a (meth) acrylate compound (B) depending on the properties of other compounds to be blended. Examples of such resins include pentaerythritol triacrylate (Kayarad PET-30 manufactured by Nippon Kayaku Co., Ltd.) and ECH-modified 1,6-hexanediol diacrylate (Kayarad R-167 manufactured by Nippon Kayaku Co., Ltd.).

  In order to further improve the wet heat durability and the interlayer adhesion of the polarizing plate, the (meth) acrylate compound (B) has one or more hydroxyl groups and one or more (meth) acryloyl groups ( It has two components of (meth) acrylate compound (a) and (meth) acrylate compound (b) having a dicyclopentadiene skeleton and having at least one (meth) acryloyl group. More preferred. Each of them may be a single type, or a plurality of types of components may be mixed. A resin composition in which the content ratio of these two component (meth) acrylate compounds (a) and (b) is 5: 9 to 11: 3 is good, and the resin comprises the ratio of the (meth) acrylate compound (B). A polarizing plate having a layer obtained from the composition is further improved in durability.

  In order to obtain a resin composition capable of improving the sufficiently stable hardness and durability of the polarizing plate, the compound having three or more (meth) acryloyl groups in (A) or (B) is a polymerizable resin composition. It is preferable that 50 to 98 parts by weight are contained in 100 parts by weight of the product. More preferably, it contains 60 parts by weight to 98 parts by weight, and more preferably 70 parts by weight to 98 parts by weight.

  The at least one (meth) acrylate compound (A) having two or more (meth) acryloyl groups is a compound containing either a pentaerythritol skeleton, a neopentyl glycol skeleton, a trimethylolpropane skeleton, or a dicyclopentadiene skeleton. It is more preferable because it improves durability. As for the compound having any one of pentaerythritol skeleton, neopentyl glycol skeleton and trimethylolpropane skeleton, at least one kind is 30 to 98 parts by weight, preferably 50 parts by weight to 100 parts by weight of the polymerizable resin composition. It is preferable to contain 98 parts by weight, more preferably 70 parts by weight to 98 parts by weight.

  Examples of the compound having a pentaerythritol skeleton include pentaerythritol triacrylate (Kayarad PET-30 manufactured by Nippon Kayaku Co., Ltd.), pentaerythritol tetraacrylate (Kayarad PET-40 manufactured by Nippon Kayaku Co., Ltd.), pentaerythritol tetramethacrylate (Sartomer Co., Ltd.). SR-367), dipentaerythritol hexaacrylate (Kayarad DPHA manufactured by Nippon Kayaku Co., Ltd.), dipentaerythritol monohydroxypentaacrylate (SR-399 manufactured by Sartomer), alkyl-modified dipentaerythritol pentaacrylate (manufactured by Nippon Kayaku Co., Ltd.) Kayarad D-310), alkyl-modified dipentaerythritol tetraacrylate (Nippon Kayaku Kayrad D-320), alkyl-modified dipentaerythritol triacrylate (Nippon Kayaku Kayalad D-330), Prolactone-modified dipentaerythritol hexaacrylate (Nippon Kayaku Kayrad DPCA-20, Nippon Kayaku Kayarad DPCA-60, Nippon Kayaku Kayrad DPCA-120), stearic acid-modified pentaerythritol diacrylate (Toa Gosei) Aronix M-233 made by the company is good. Preferably, pentaerythritol triacrylate (Kayarad PET-30 manufactured by Nippon Kayaku Co., Ltd.) is most preferable.

  Examples of the compound having a neopentyl glycol skeleton include neopentyl glycol dimethacrylate (FA-125M manufactured by Hitachi Chemical Co., Ltd.), neopentyl glycol diacrylate (Kayarad NPGDA manufactured by Nippon Kayaku Co., Ltd.), neopentyl glycol diacrylate (Sartomer). SR-248), hydroxypivalate neopentyl glycol diacrylate (Nippon Kayaku Kayrad MANDA), caprolactone-modified hydroxypivalate neopentyl glycol diacrylate (Nippon Kayaku Kayrad HX series), alicyclic modification Neopentyl glycol acrylate (Kayarad R-629, Nippon Kayaku Co., Ltd., Kayrad R-644, Nippon Kayaku Co., Ltd.) or Bis (acryloxyneopentyl glycol) adipate (Kayarad R-526, Nippon Kayaku Co., Ltd.) is available.

  Examples of the compound having a trimethylolpropane skeleton include, for example, trimethylolpropane triacrylate (Kayarad TMPTA, manufactured by Nippon Kayaku Co., Ltd.), trimethylolpropane trimethacrylate (SR-350, manufactured by Sartomer), ditrimethylolpropane tetraacrylate (Sartomer). SR-355), neopentyl glycol modified trimethylolpropane diacrylate (Kayarad R-604 manufactured by Nippon Kayaku Co., Ltd.), EO modified trimethylolpropane triacrylate (SR-450 manufactured by Sartomer), PO modified trimethylolpropane triacrylate (Kayarad TPA-series manufactured by Nippon Kayaku Co., Ltd.) or ECH-modified trimethylolpropane triacrylate (Denar DA-321 manufactured by Nagase Sangyo Co., Ltd.).

  When at least one of the above compounds is mixed, the (meth) acrylate compound (A) is 30 to 98 parts by weight, more preferably 50 parts, in 100 parts by weight of the polymerizable resin composition excluding the solvent. It is preferable to contain 70 to 98 parts by weight, more preferably 70 to 98 parts by weight. The (meth) acrylate compound (B) is 10 to 60 parts by weight, more preferably 20 to 60 parts by weight, and even more preferably 30 to 60 parts by weight in 100 parts by weight of the polymerizable resin composition excluding the solvent. It is preferably contained in parts by weight.

  When the compound used in the present invention or the resin composition thereof is a resin composition that is polymerized by ultraviolet rays, a polymerization reaction is caused by using an ultraviolet polymerization initiator. Examples of the ultraviolet polymerization initiator include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 (Irgacure 907 manufactured by Ciba Specialty Chemicals), 1-hydroxycyclohexyl phenyl ketone (Ciba Specialty). Chemicals Irgacure 184), 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone (Irgacure 2959 from Ciba Specialty Chemicals), 1- (4-dodecylphenyl) -2-hydroxy 2-methylpropan-1-one (Merck Darocur 953), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (Merck Darocur 1116), 2-hydroxy-2- Methyl-1-phenylpropa -1-one (Irgacure 1173 manufactured by Ciba Specialty Chemicals), acetophenone compounds such as diethoxyacetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, or 2,2-dimethoxy-2- Benzoin compounds such as phenylacetophenone (Irgacure 651 manufactured by Ciba Specialty Chemicals), benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, or 3,3 ′ -Benzophenone compounds such as dimethyl-4-methoxybenzophenone (Nippon Kayaku MBP), thioxanthone, 2-chloro Xanthone (Nippon Kayaku Caya Cure CTX), 2-Methylthioxanthone, 2,4-Dimethylthioxanthone (Kaya Cure RTX), Isopropylthioxanthone, 2,4-Dichlorothioxanthone (Nippon Kayaku Caya Cure CTX) Thioxanthone compounds such as 2,4-diethylthioxanthone (Nippon Kayaku Kayacure DETX) or 2,4-diisopropylthioxanthone (Nippon Kayaku Kyakuure DITX). More preferably, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 (Irgacure 907 manufactured by Ciba Specialty Chemicals), 1-hydroxycyclohexyl phenyl ketone (Irgacure manufactured by Ciba Specialty Chemicals) 184), 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651 manufactured by Ciba Specialty Chemicals) is preferable. These ultraviolet polymerization initiators can be used singly or in combination at any blending ratio.

  When a benzophenone compound or a thioxanthone compound is used, an auxiliary agent can be used in combination in order to accelerate the ultraviolet polymerization reaction. Examples of such auxiliaries include triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler's ketone, 4,4′-diethylaminophenone, 4-dimethylaminobenzoic acid. Examples include amine compounds such as ethyl, ethyl 4-dimethylaminobenzoate (n-butoxy) or isoamyl 4-dimethylaminobenzoate.

  The addition amount of the ultraviolet polymerization initiator and the auxiliary agent is preferably used within a range where the polarization performance does not deteriorate, and the amount thereof is 100 parts by weight of the (meth) acrylate compound in the polymerizable composition. The amount is preferably 0.5 to 12 parts by weight, more preferably about 2 to 10 parts by weight. Further, the auxiliary agent is preferably about 0.5 to 2 times the amount of the ultraviolet polymerization initiator.

  When the compound used in the present invention or the resin composition thereof is a thermopolymerizable resin composition, a polymerization initiator, a crosslinking agent and / or an initiation catalyst are used. As the type of the crosslinking agent, various known compounds such as isocyanate, boron, and titanate can be used. The addition amount is 0.1 to 20 parts by weight in 100 parts by weight of the polymerizable resin composition, more preferably about 1 to 10 parts by weight in 100 parts by weight of the composition.

  As a method of forming a layer of a polymerizable resin composition on a polarizing plate, for example, the composition is directly or diluted with an appropriate solvent and applied to a PVA film on which a protective layer or a dichroic dye is adsorbed and oriented. To do. Thereafter, the solvent is removed by heating or the like, and a layer obtained by curing the polymerizable resin composition can be obtained by heating or irradiation with ultraviolet rays. The solvent of the solution of the composition used for coating is not particularly limited as long as it is excellent in solubility of the composition and wettability on the substrate during coating and does not cause deterioration in surface properties. Examples of such solvents include aromatic hydrocarbons such as toluene and xylene, ethers such as anisole, dioxane and tetrahydrofuran, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 2-pentanone, 3-pentanone, Ketones such as 2-hexanone, 3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone or 2,6-dimethyl-4-heptanone, alcohols such as n-butanol, 2-butanol, cyclohexanol and isopropyl alcohol , Cellosolves such as methyl cellosolve and methyl cellosolve, ethyl acetate, butyl acetate, methyl lactate, propylene glycol monomethyl ether acetate, propylene glycol ethyl ether acetate, methoxyethyl acetate Or fence esters of ethoxyethyl and the like, dimethyl sulfoxide, acetonitrile, N, N-but-dimethylacetamide formamide without limitation. Toluene, cyclopentanone, and ethyl acetate are preferable. The solvent may be a single solvent or a mixture. The concentration of the composition at the time of dissolving the composition varies depending on solvent solubility, wettability on the substrate, thickness after coating, etc., but is preferably 5 to 95% by weight, more preferably 10 to 80% by weight. The degree is good.

  In addition, when the wettability onto the substrate is poor or the surface property of the formed composition layer is poor when applied onto the substrate, various leveling levels are included in the composition in order to improve them. It is also possible to add an agent. As the type of leveling agent, various compounds such as silicon-based, fluorine-based, polyether-based, acrylic acid copolymer-based and titanate-based compounds can be used. The added amount is 0.0001 part by weight or more and 10 parts by weight or less, more preferably 0.1 part by weight or more and 5 parts by weight or less in 100 parts by weight of the composition in 100 parts by weight of the polymerizable resin composition. .

  After the composition layer formed on the substrate is cured, if the adhesion between the cured layer and the protective film is poor, various crosslinking agents may be added to the composition in order to improve them. Is possible. As the type of the crosslinking agent, various compounds such as isocyanate, boron, and titanate can be used. The addition amount is 0.0001 part by weight or more and 20 parts by weight or less in 100 parts by weight of the polymerizable resin composition, more preferably 0.1 part by weight or more and 10 parts by weight or less in 100 parts by weight of the composition. .

  As a method of forming a layer of a polymerizable resin composition on a polarizing plate, a resin layer may be provided by coating on a protective layer or film, or directly coated on a PVA film on which dichroic dye and boric acid are adsorbed. A layer may be provided by a method such as Alternatively, the protective layer or the dichroic dye is not only applied to the PVA film that is adsorbed and oriented, but is applied to another film in advance, and the cured layer is applied to the protective layer or the dichroic dye that is adsorbed and oriented A method of transferring or laminating may be used. Furthermore, the method of providing the resin layer at the same time as providing the adhesive layer is also efficient, and the polarizing plate can be most easily produced when the resin composition to be the adhesive layer is a polymerizable resin composition. The application method is not particularly limited, and examples thereof include a spin coating method, a wire bar coating method, a gravure coating method, a micro gravure coating method, a calendar coating method, a spray coating method, a meniscus coating method, and the like.

It is preferable that the cured layer made of the polymerizable resin composition used in the present invention is sufficiently polymerized by heating or ultraviolet irradiation and has as little unreacted content as possible. The degree is 0 to 5 parts by weight of unreacted (meth) acrylate compound in 100 parts by weight of the cured resin composition, more preferably 0 to 3 parts by weight, and still more preferably 0 parts by weight. It is preferable that the amount be 1 part by weight or more. As a method for obtaining such a layer, for example, a method for optimizing the thickness of the layer of the resin composition after coating, a method for optimizing the type and amount of the UV polymerization initiator to be added, sufficient heating or UV irradiation A method of irradiating, a method of changing the atmosphere at the time of ultraviolet irradiation, such as performing in an inert gas such as nitrogen, and the like, are exemplified. The simple method is the simplest because the method of optimizing the thickness of the resin layer can be optimized only by changing the resin concentration or changing the resin coating amount. The thickness of the layer obtained by curing the polymerizable resin composition is preferably 0.5 to 10 μm, more preferably 1 to 8 μm, and still more preferably 2 to 6 μm. If it is thicker than 10 μm, the residual unreacted monomer increases, the wet heat durability may decrease, and the polarizing plate turns red in the dry heat durability test, which is not suitable. On the other hand, a layer thinner than 0.5 μm does not lead to improvement in wet heat durability. The irradiation amount of ultraviolet rays varies depending on the type of (meth) acrylate compound, the type and addition amount of the ultraviolet polymerization initiator, and the film thickness, but is preferably about 100 to 1500 mJ / cm ² , for example.

  Moreover, it is preferable that the layer which consists of polymeric resin compositions is transparent even if it processes with an alkaline solution. Specifically, one of the indicators is that there is no cloudiness after treatment with an alkaline aqueous solution having a pH of 11 or more at 40 ° C. for 10 minutes or more. As a standard, a film having a cured layer coated with an ultraviolet curable resin composition having a thickness of 5 μm on polyethylene terephthalate and treated with an aqueous solution of pH 11 at 40 ° C. for 10 minutes or more, even at a wavelength of 550 nm The light transmittance is preferably 85% or more, and preferably 90% or more. On the other hand, it is more preferable to make the layer made of the polymerizable resin composition hydrophilic by treating the layer made of the polymerizable resin composition with an alkaline aqueous solution, because the adhesion to the PVA film is improved. As an index of hydrophilicity at that time, the contact angle when 10 μl of water is dropped is preferably 60 ° or less, more preferably 50 ° or less, and still more preferably 40 ° or less. In the case of bonding to a polarizing element film, it is preferable to use a solution to which neutralization treatment is performed with water or an acidic aqueous solution after treatment with an alkaline aqueous solution and then a drying treatment is applied.

  When trying to obtain a polarizing plate having high durability in a wet heat test, not only one layer obtained by curing the polymerizable resin composition but also a multilayer structure of two or more layers. Thus, the wet heat durability is further improved.

  When a layer obtained by curing such a resin composition is provided on the polarizing plate, the protective layer (L) / adhesive layer (L) / polarizing element film / adhesive layer (M) / protective layer (M) / adhesive layer The durability can be further improved by providing one or more layers between or on any of the layers of the polarizing plate. Specifically, one of the surface of the protective layer not facing the adhesive layer, between the protective layer and the adhesive layer, or between the adhesive layer and the hydrophilic polymer film in which the dichroic dye is adsorbed and oriented. This is achieved by providing more than one layer. In order to further improve the wet heat durability, it is effective to provide a layer obtained by curing a polymerizable resin on the surface side that becomes an exposed surface after being bonded to a display device. Specifically, it shows the surface of the protective layer (L), between the protective layer (L) and the adhesive layer (L), and between the adhesive layer (L) and the polarizing element film. Preferably, the space between the protective layer (L) and the adhesive layer (L) and the space between the adhesive layer (L) and the polarizing element film are preferable. Further, in order to further enhance the wet heat durability improving effect, a layer obtained by curing the resin composition may be provided on both sides one by one or two or more layers through a PVA film having a dichroic dye adsorbed and oriented. More preferable. Moreover, it is preferable to have it in the layer close | similar to a polarizing element film in that case in order to improve durability further. Specifically, it is preferably provided on both surfaces between the protective layer (L) and the polarizing element film and between the polarizing element film and the protective layer (M). Further, in order to easily improve the adhesion and to prevent migration of unreacted monomers of the polymerizable resin composition, an anchor coat layer or a separate layer is provided between the polarizing element film and the layer obtained by curing the polymerizable resin composition. An adhesive layer may be provided.

  The polarizing plate of this invention characterized by providing the layer which hardened | cured polymeric resin composition by the above process at least 1 layer or more is obtained.

  The obtained polarizing plate is preferably provided with a transparent protective layer on at least one side or both sides. The transparent protective layer can be provided by forming a layer by coating with a polymer or laminating a film. The transparent polymer or film forming the transparent protective layer is preferably a transparent polymer or film having high mechanical strength and good thermal stability. Examples of substances used as the transparent protective layer include cellulose acetate resins such as triacetyl cellulose and diacetyl cellulose or films thereof, acrylic resins or films thereof, polyvinyl chloride resins or films thereof, polyester resins or films thereof, polyarylate resins or The film, a cyclic polyolefin resin having a cyclic olefin such as norbornene or the film thereof, polyethylene, polypropylene, a polyolefin having a cyclo or norbornene skeleton or a copolymer thereof, and the main chain or side chain of which is imide and / or amide Examples thereof include a resin, a polymer, or a film thereof. A resin having liquid crystallinity or a film thereof may be provided. The thickness of the protective film is, for example, about 0.5 to 200 μm. A polarizing plate is preferably prepared by providing one or more layers of the same or different types of resins or films on one or both sides.

  Various functional layers and / or pressure-sensitive adhesive layers can be provided on one surface of the obtained polarizing plate, specifically, on the surface of a protective layer or film that becomes a non-exposed surface after being bonded to a display device. By providing the pressure-sensitive adhesive layer, a polarizing plate can be attached to a display device such as various functional layers, liquid crystal, or organic electroluminescence. The various functional layers may be layers or films for controlling the phase difference.

  This polarizing plate has an antireflection layer, an antiglare layer, a hard coat layer, a liquid crystal coating for improving the viewing angle and / or contrast on the exposed surface of the cured layer, protective layer or film of the polymerizable resin composition. You may have various well-known functional layers, such as a construction layer. A coating method is preferable for producing the layer having various functions, but a film having the function may be bonded via an adhesive or a pressure-sensitive adhesive.

  In providing a transparent protective layer on a polarizing element film, when the protective layer is a film, it is necessary to perform film lamination. In that case, an adhesive is required. The adhesive is not limited, and a known adhesive can be used. When one or more layers obtained by curing the polymerizable resin composition are provided on the surface of the protective layer not in contact with the adhesive layer or between the protective layer and the adhesive layer, the protective layer and the polarizing element film, or the polymerizable layer, respectively. The layer obtained by curing the resin composition and the polarizing element film are adhered to each other. Polyvinyl alcohol-based adhesion can be used as an adhesive in that case. Examples of the polyvinyl alcohol-based adhesive include Gohsenol NH-26 (manufactured by Nihon Gosei Co., Ltd.), Exeval RS-2117 (manufactured by Kuraray Co., Ltd.), and Goose Famer Z-200 (manufactured by Nihon Gosei Co., Ltd.) It is not limited. A cross-linking agent such as glyoxal or glutaraldehyde and / or a water-resistant agent may be added to the adhesive. Moreover, it is preferable that the adhesive contains an acidic substance such as sulfuric acid, acetic acid, hydrochloric acid, formic acid, aluminum sulfate, or aluminum chloride at a concentration of 0.0001 to 20 wt%, and 0.02 to 5 wt%. Is more preferable. As the polyvinyl alcohol-based adhesive, an adhesive in which only a maleic anhydride-isobutylene copolymer / and a crosslinking agent are mixed can be used. As maleic anhydride-isobutylene copolymers, for example, isoban # 18 (manufactured by Kuraray), isoban # 04 (manufactured by Kuraray), ammonia-modified isoban # 104 (manufactured by Kuraray), ammonia-modified isoban # 110 (manufactured by Kuraray) ), Imidized isoban # 304 (manufactured by Kuraray), imidized isoban # 310 (manufactured by Kuraray), and the like. A water-soluble polyvalent epoxy compound can be used as the crosslinking agent at that time. Examples of the water-soluble polyvalent epoxy compound include Denacol EX-521 (manufactured by Nagase Chemtech) and Tetrat-C (manufactured by Mitsui Gas Chemical Co., Ltd.). As other adhesives, urethane-based, acrylic-based, and epoxy-based adhesives are frequently used, and known adhesives can be used, but the adhesive is not limited. Further, as an additive for the adhesive, a zinc compound, chloride, iodide and the like can be simultaneously contained at a concentration of about 0.1 to 10% by weight. The additive is not limited. After laminating the transparent protective layer with an adhesive, the polarizing plate is obtained by drying or heat treatment at a suitable temperature.

  By the above method, the ultraviolet curable resin composition in this invention and the polarizing plate which has the layer which hardened it can be obtained. The polarizing plate obtained by the present invention is a polarizing plate with little change in transmittance and lowering of the degree of polarization at a temperature of 65 ° C. and a relative humidity of 93% RH in a humid heat environment. The number of polarizing plates is small, and a highly reliable polarizing plate can be obtained even under severe conditions. A polarizing plate for display, particularly a polarizing plate with high transmittance, high contrast, and high wet heat durability in a liquid crystal display can be obtained. A display using this is a display having high reliability, long-term high contrast, and high color reproducibility.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these. In addition, the transmittance | permeability and polarization degree which are shown to an Example were performed as follows.

  The transmittance when the two polarizing plates obtained by bonding the protective films on both sides of the polarizing element film are stacked so that the absorption axis directions are the same is the parallel transmittance Tp, and the two polarizing plates The transmittance when the absorption axes are stacked so that the absorption axes are orthogonal to each other is defined as the orthogonal transmittance Tc.

  The transmittance T was calculated from the following formula (1) by obtaining the spectral transmittance τλ at predetermined wavelength intervals dλ (here, 5 nm) in the wavelength region of 400 to 700 nm. In the equation, Pλ represents a spectral distribution of standard light (C light source), and yλ represents a 2 ° visual field color matching function.

  The spectral transmittance τλ was measured using a spectrophotometer [“U-4100” manufactured by Hitachi, Ltd.].

  The degree of polarization Py was determined by the following formula (2) from the parallel transmittance Tp and the orthogonal transmittance Tc.

Py = {(Tp−Tc) / (Tp + Tc)} ^1/2 × 100 (2)

  Furthermore, in the color system shown by JIS Z8729 (color display method L *, a *, b * display system and L *, u *, v * color system) about the hue of the polarizing plate, a * and b * were measured. The term “orthogonal hue” as used herein means that the measurement was performed in a state where two polarizing plates were overlapped so that their absorption axes were orthogonal to each other. In the L *, a *, and b * color systems, the hues indicate neutral colors as a * and b * are closer to zero.

Example 1
A PVA film (VF-XS manufactured by Kuraray Co., Ltd.) having a thickness of 75 μm, a polymerization degree of 2400, and a saponification degree of 99% or more was swollen with warm water at 40 ° C., and then dyed with an aqueous solution containing iodine, potassium iodide and boric acid. Went. The dyed film was stretched 5 times in a solution containing 3% by weight of boric acid, and after stretching, an aqueous solution of pH 2.2 containing 5% by weight of potassium iodide and 0.03% by weight of citric acid. Soaked in. A film immersed in an aqueous potassium iodide solution for 15 seconds was dried with a dryer at 70 ° C. for 10 minutes to obtain a polarizing element film. The obtained polarizing element film was obtained by laminating a triacetyl cellulose film (TD-80UF manufactured by Fuji Photo Film Co., Ltd., hereinafter abbreviated as TAC) on both sides as a protective layer to obtain a polarizing plate.

Next, 100 parts by weight of dipentaerythritol hexaacrylate (DPHA manufactured by Nippon Kayaku Co., Ltd.) and 5 parts by weight of Irgacure 184 (manufactured by Ciba Specialty Chemicals) were stirred and mixed to obtain an ultraviolet curable resin composition used in the present invention. . This composition was diluted with methyl ethyl ketone (manufactured by Junsei Chemical Co., Ltd.) to prepare a solution having a solid content concentration of 50% by weight. This solution is applied to the surface of a polarizing plate cut into 40 mm × 40 mm and bonded to a transparent glass plate having a thickness of 1 mm via an adhesive PTR-3000 (manufactured by Nippon Kayaku Co., Ltd.), and the solvent is removed by heating. The film thickness after removal was set to 3 μm. The solvent was dried at 50 ° C. for 3 minutes, then irradiated with a high-pressure mercury lamp (integrated light amount 400 mJ / cm ² ) in the air and cured to obtain a polarizing plate having a layer having the polymerizable resin composition of the present invention. The layer structure of the sample is a structure obtained by the polymerizable resin composition / TAC / adhesive layer / polarizing element film / adhesive layer / TAC / adhesive layer / glass layer.

  A wet heat test and a dry heat test were performed using the prepared samples. In the wet heat test, the transmittance and polarization degree were measured before and after leaving for 1000 hours in an atmosphere of a temperature of 65 ° C. and a relative humidity of 93%. In the dry heat test, the transmittance, polarization degree, and orthogonal hue a * (hereinafter abbreviated as a * -c) were measured before and after leaving at a temperature of 90 ° C. for 1000 hours.

Example 2
In Example 1, the polymerizable resin composition was mixed with 50 parts by weight of dipentaerythritol hexaacrylate (Nippon Kayaku DPHA), 50 parts by weight of pentaerythritol triacrylate (PET-30 manufactured by Nippon Kayaku Co., Ltd.), Irgacure 184 (Ciba Specialty). Made by Tea Chemicals) 5 parts by weight, except that a polarizing plate having a layer obtained by a polymerizable resin composition containing a (meth) acrylate compound having a hydroxyl group was obtained in the same manner to produce a polarizing plate, The durability in the wet heat test and the dry heat test was confirmed.

Example 3
In Example 1, the polymerizable resin composition was mixed with 60 parts by weight of pentaerythritol triacrylate (PET-30 manufactured by Nippon Kayaku Co., Ltd.), 30 parts by weight of dicyclopentenylethyl methacrylate (Hitachi Chemical FA-512M), Irgacure 184 (Ciba Specialty). (Product made by Tea Chemicals) The polarizing plate was the same except that a polarizing plate having a layer obtained by a polymerizable resin composition containing a (meth) acrylate compound containing a dicyclopentanyl skeleton was obtained instead of 5 parts by weight. And the durability in the wet heat test and the dry heat test was confirmed.

Example 4
In Example 1, a polarizing element film was similarly formed except that the potassium iodide-treated aqueous solution after stretching was made into an aqueous solution having a pH of 4.5 by adding 5% by weight of potassium iodide and 0.01% by weight of citric acid. A polarizing plate was produced in the same manner except that it was produced, and durability in a wet heat test and a dry heat test was confirmed.

Example 5
In Example 1, 50 parts by weight of dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.) was added to a triacetyl cellulose film (TD-80UF, manufactured by Fuji Photo Film Co., Ltd.), and pentaerythritol triacrylate (Japan). Changed to 30 parts by weight of PET-30 manufactured by Kayaku Co., Ltd., 20 parts by weight of dicyclopentanyl acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-513A), 5 parts by weight of Irgacure 184 (manufactured by Ciba Specialty Chemicals) A transparent protective film having a layer obtained by applying a polymerizable resin composition to a thickness of 3 μm and irradiating ultraviolet rays in air with a high-pressure mercury lamp (integrated light amount 400 mJ / cm ² ). Was made. The surface of the layer was brought into contact with an alkaline aqueous solution of pH 11 for 10 minutes, and the contact angle with water on the surface of the layer was reduced from 80 ° to 57.2 °. The layer in which the polymerizable resin composition is cured is adhered to the polarizing element obtained by the formulation of Example 1 using an adhesive, and the configuration is a layer / adhesive layer in which the TAC / polymerizable resin composition is cured. A polarizing plate having / polarizing element film / adhesive layer / TAC was obtained. Layer / adhesive layer / polarized light in which the polarizing plate is cut into 40 mm × 40 mm and bonded to a 1 mm glass plate via an adhesive (PTR-3000 manufactured by Nippon Kayaku Co., Ltd.), and the TAC / polymerizable resin composition is cured. The wet heat test and dry heat durability were confirmed with the constitution of base film / adhesive layer / TAC / adhesive layer / glass.

Example 6
In Example 5, a layer obtained by curing the polymerizable resin composition was provided on both sides of the polarizing element film, and a layer obtained by curing the TAC / polymerizing resin composition / adhesive layer / polarizing element film / adhesive layer / polymerization. A sample was prepared in the same manner except that a polarizing plate having a configuration of curable resin composition / layer / TAC was obtained, and a wet heat test and a dry heat test were confirmed.

Example 7
A sample was prepared in the same manner as in Example 1 except that the polarizing plate was obtained by setting the layer obtained from the polymerizable resin composition to 0.3 μm, and the wet heat test and the dry heat test were confirmed.

Example 8
In Example 1, a sample was prepared in the same manner except that the polarizing plate was obtained by setting the layer obtained from the polymerizable resin composition to 1.2 μm, and the wet heat test and the dry heat test were confirmed.

Example 9
In Example 1, a sample was prepared in the same manner except that the polarizing plate was obtained by setting the layer obtained from the polymerizable resin composition to 9 μm, and the wet heat test and the dry heat test were confirmed.

Example 10
Samples were prepared in the same manner as in Example 1 except that the polarizing plate was obtained by setting the layer obtained from the polymerizable resin composition to 20 μm, and the wet heat test and the dry heat test were confirmed.

Comparative Example 1
In Example 1, a polarizing element film obtained by treating a potassium iodide-treated aqueous solution after stretching without adding citric acid and treating the aqueous solution with an aqueous solution having a pH of 6.8, and using a polymerizable resin composition The durability in the wet heat test and the dry heat test was confirmed in the same manner except that the resulting layer was not provided.

Comparative Example 2
In Example 1, the durability in the wet heat test and the dry heat test was confirmed in the same manner except that the layer obtained from the polymerizable resin composition was not provided.

Comparative Example 3
A wet heat test was conducted in the same manner as in Example 1 except that a polarizing element film treated with an aqueous solution having a pH of 6.8 was used without adding citric acid to the potassium iodide-treated aqueous solution after stretching. The durability in the dry heat test was confirmed.

Comparative Example 4
In Example 1, except that the polarizing element film was similarly prepared except that the potassium iodide-treated aqueous solution after stretching was made into an aqueous solution having a pH of 0.8 by adding 5% by weight of potassium iodide and sulfuric acid. A polarizing plate was prepared, and durability in a wet heat test and a dry heat test was confirmed.

Comparative Example 5
A sample was prepared in the same manner as in Example 10 except that a polarizing element film treated with an aqueous solution having a pH of 6.8 was used without adding citric acid to the potassium iodide-treated aqueous solution after stretching. The wet heat test and the dry heat test were confirmed.

Comparative Example 6
JP-A-2003-185842 According to Example 1, iodine and boric acid were adsorbed on a PVA film, and dicyclopentenyloxyethyl methacrylate (FA-512M, manufactured by Hitachi Chemical Co., Ltd.) 100 weight on the surface of the polarizing element film stretched 5 times. D1173 (polymerization initiator, manufactured by Merck & Co., Inc.) 5 parts by weight is coated such that the thickness of the polymerizable cured product layer is 20 μm, and is obtained by curing with a metal halide lamp by irradiating ultraviolet rays at 400 mJ / cm ^2. A plate was prepared, and durability in a wet heat test and a dry heat test was confirmed.

  Table 2 shows the measurement results of wet heat test 65 ° C., relative humidity 93%, transmittance after 1000 hours, and change in polarization degree in Examples 1 to 10 and Comparative Examples 1 to 6. In the table, Ys0 is the initial transmittance, ρ0 is the initial polarization degree, Ys-Wet is the transmittance after 65 ° C x 93% RHx 1000 hours, ρ-Wet is the transmittance after 65 ° C x 93% RHx 1000 hours, and ΔYs is 65 ° C from the initial stage. The transmittance change amount after 1000 hours of x93% RHx, and Δρ represents the change amount of polarization degree after 1000 hours from 65 ° C. × 93% RHx.

Table 2

  Table 3 shows measurement results of transmittance and change in polarization degree after 90 hours at 90 ° C. in the dry heat test in Examples 1 and 2 and Comparative Examples 1 to 3. In the table, Ys0 is the initial transmittance, ρ0 is the initial polarization degree, a * -c0 is the initial a * -c value, Ys1000 is the transmittance after 90 ° C. × 1000 hours, ρ1000 is the polarization degree after 90 ° C. × 1000 hours, a * -c1000 indicates a * -c after 90 ° C. × 1000. The higher the a * -c value, the more red the color is.

Table 3

  As is clear from the above Examples and Comparative Examples, the present invention relates to a hydrophilic polymer film that has been drawn and adsorbed with a dichroic dye and boric acid as a solution having a pH of 1.0 to 6.0. A polarizing plate comprising a polarizing element film, wherein the polarizing element film is provided with at least one layer obtained by curing a polymerizable resin composition. It can be seen that a polarizing plate can be obtained in which wet heat durability is greatly improved and color change does not occur even in dry heat durability. For example, the durability at 65 ° C. and 93% relative humidity is improved, the change in transmittance and the decrease in the polarization degree are suppressed, and the decrease in the polarization degree is small and the redness is small in the dry heat test, for example, 90 ° C. It was shown to be a polarizing plate. Without treatment with a solution having a pH of the polarizing element film of 1.0 to 6.0, dry heat durability, for example, the decrease in the degree of polarization is large at 90 ° C., the redness of the polarizing plate is large, and the durability is not good. It turns out that it is enough. In Examples 1 to 3, it can be seen that the difference in the polymerizable composition used shows a difference in wet heat durability, and in Examples 5 and 6, it can be seen that the durability is greatly improved by the layer structure. From Examples 1 and 7 to 10, it can be seen that the film thickness is related to the durability. Further, when Example 10 and Comparative Example 5 are compared, in the polarizing plate having a layer made of a polymerizable resin composition having a film thickness of 20 μm, the polarizing element film treated with a solution having a pH of 1.0 to 6.0 is used. It can be seen that the change in a * -c at 90 ° C. in the dry heat test can be greatly suppressed by using it. As can be seen from a comparison between Example 1 and Comparative Example 3, it can be seen that redness increases at pH 6 or higher. On the other hand, as can be seen from Comparative Example 4, the transmittance of the polarizing element film treated at pH 1 or lower is greatly reduced in the dry heat test. From the above, the polarizing plate obtained by the present invention has greatly improved wet heat durability and has become a polarizing plate in which no color change occurs even in a dry heat test.

Claims (18)

A polarizing plate using a polarizing element film obtained by treating a hydrophilic polymer film drawn by adsorbing a dichroic dye and boric acid with a solution having a pH of 1.0 to 6.0, A polarizing plate comprising at least one layer obtained by curing a polymerizable resin composition on a polarizing plate. The polarizing plate according to claim 1, wherein the thickness of the layer obtained by curing the polymerizable resin composition is 0.5 μm to 10 μm. The polarizing plate according to claim 1, comprising one or more polymerizable resin compositions and one or more protective layers on both surfaces or at least one surface of the polarizing element film. The polymerizable resin composition is a (meth) acrylate compound having two or more (meth) acryloyl groups, and when the cured resin film layer has a film thickness of 5 μm, the moisture permeability of the resin film layer is 24 hours. Contains at least one (meth) acrylate compound (A) and a polymerization initiator (C) of 1500 g / m ² or less, or has a solubility in water of (A) and 25 ° C. of 1% by weight or less The polarizing plate according to any one of claims 1 to 3, wherein the polarizing plate is a polymerizable resin composition containing at least one (meth) acrylate compound (B) and a polymerization initiator (C). The (meth) acrylate compound (B) is a (meth) acrylate compound (a) having at least one hydroxyl group and at least one (meth) acryloyl group in the molecule. Item 5. The polarizing plate according to item 4. The (meth) acrylate compound (B) is a (meth) acrylate compound (b) having a dicyclopentadiene skeleton and having at least one (meth) acryloyl group. Polarizing plate. The compound (b) having a dicyclopentadiene skeleton of the (meth) acrylate compound (B) is a compound having a dicyclopentanyl skeleton or a dicyclopentenyl skeleton and a (meth) acryloyl group. Polarizer. The (meth) acrylate compound (B) has one or more hydroxyl groups, and has a (meth) acrylate compound (a) having one or more (meth) acryloyl groups, a dicyclopentadiene skeleton, and And (meth) acrylate compound (b) having one or more (meth) acryloyl groups, and the weight ratio of (meth) acrylate compound (a) and (b) is from 5: 9 to 11: 3. The polarizing plate according to claim 1, wherein the polarizing plate is a polymerizable resin composition. 9. The compound according to claim 1, wherein the (meth) acrylate compound (A) is a compound having any one of a pentaerythritol skeleton, a neopentyl glycol skeleton, and a trimethylolpropane skeleton, and a (meth) acryloyl group. The polarizing plate as described in a term. 30 to 96 parts by weight of at least one or more (meth) acrylate compounds (A) in 100 parts by weight of the polymerizable resin composition excluding the solvent, and at least one or more (meth) acrylates other than (A) It has a layer obtained by curing a polymerizable resin composition containing 0 to 60 parts by weight of the compound (B) and 2 to 10 parts by weight of the polymerization initiator (C). The polarizing plate according to claim 1, wherein at least one layer having a thickness of 5 to 10 μm is provided. The (meth) acrylate compound (A) or (B) has three or more (meth) acryloyl groups, and at least one of the compounds is 50 weight parts in 100 weight parts of the polymerizable resin composition excluding the solvent. The polarizing plate as described in any one of Claims 1 thru | or 10 which has a layer which hardened the polymeric resin composition characterized by containing more than one part. In the polarizing plate composed of a protective layer / adhesive layer / polarizing element film / adhesive layer / protective layer, at least one layer is provided between the protective layer and the polarizing element film in which the layer obtained by curing the polymerizable resin composition is formed. The polarizing plate as described in any one of Claims 1 thru | or 11 characterized by the above-mentioned. Polarized light in which a layer obtained by curing the polymerizable resin composition is composed of a protective layer (L) / adhesive layer (L) / polarizing element film / adhesive layer (M) / protective layer (M) / adhesive layer The polarizing plate according to claim 1, wherein at least one layer is provided between the protective layer (L) and the polarizing element film in the plate. In the polarizing plate constituted by the protective layer (L) / adhesive layer (L) / polarizing element film / adhesive layer (M) / protective layer (M) / adhesive layer, the polymerizable resin composition was cured. At least one layer is provided between the protective layer (L) and the adhesive layer (L), between the protective layer (M) and the adhesive layer (M). The polarizing plate according to any one of claims 1 to 13. The polarizing plate according to claim 1, wherein the polymerizable resin composition is an ultraviolet curable resin composition. The polarizing plate according to claim 1, wherein the protective layer is triacetyl cellulose. The dichroic dye is iodine, and the polarizing plate according to any one of claims 1 to 16. In producing a polarizing plate provided with at least one layer obtained by curing a polymerizable resin composition having a thickness of 0.5 μm to 10 μm, a dichroic dye and boric acid were adsorbed and oriented. The method for producing a polarizing plate according to claim 1, wherein the hydrophilic polymer film is treated with a solution having a pH of 1.0 to 6.0.