JP6960234B2 - Polarizing film with adhesive layer and image display device - Google Patents

Description

The present invention relates to a polarizing film and a polarizing film with an adhesive layer having an adhesive layer provided on the polarizing film. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, and a PDP using the polarizing film with an adhesive layer.

In a liquid crystal display device or the like, it is indispensable to arrange polarizing elements on both sides of a liquid crystal cell due to the image forming method, and generally, a polarizing film is attached. When the polarizing film is attached to the liquid crystal cell, an adhesive is usually used. Further, in order to reduce the loss of light, the polarizing film and the liquid crystal cell are usually adhered to each other by using an adhesive. In such a case, since there is an advantage that a drying step is not required to fix the polarizing film, the pressure-sensitive adhesive is polarized light with a pressure-sensitive adhesive layer previously provided as a pressure-sensitive adhesive layer on one side of the polarizing film. Films are commonly used. A release film is usually attached to the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer.

At the time of manufacturing the liquid crystal display device, when the polarizing film with the pressure-sensitive adhesive layer is attached to the liquid crystal cell, the release film is peeled from the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer. Static electricity is generated. The static electricity generated in this way affects the orientation of the liquid crystal inside the liquid crystal display device and causes defects. In addition, display unevenness may occur due to static electricity when using the liquid crystal display device. The generation of static electricity can be suppressed, for example, by forming an antistatic layer on the outer surface of the polarizing film, but the effect is small and there is a problem that the generation of static electricity cannot be fundamentally prevented. Therefore, in order to suppress the generation of static electricity at the fundamental position, it is required to impart an antistatic function to the adhesive layer. As a means for imparting an antistatic function to the pressure-sensitive adhesive layer, for example, it has been proposed to add an ionic compound to the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer (Patent Documents 1 to 3). Specifically, Patent Document 1 proposes a pressure-sensitive adhesive composition for an optical film containing an alkali metal salt and / or an organic cation-anion salt. Patent Document 2 proposes a pressure-sensitive adhesive composition containing an onium-anion salt and an alkali metal salt as a raw material for the pressure-sensitive adhesive layer of a polarizing film with a pressure-sensitive adhesive layer. Patent Document 3 proposes a pressure-sensitive adhesive composition containing an alkali metal salt as a raw material for the pressure-sensitive adhesive layer of a pressure-sensitive polarizing plate.

Japanese Unexamined Patent Publication No. 2015-199942 Japanese Unexamined Patent Publication No. 2014-48497 Japanese Unexamined Patent Publication No. 2012-247574

As the polarizing film with an adhesive layer, a polarizing film with an adhesive layer provided with an adhesive layer may be used without providing a transparent protective film on only one side of the polarizer and without providing a transparent protective film on the other side. be. Since the polarizing film with the pressure-sensitive adhesive layer has the transparent protective film on only one side, the cost for one layer of the transparent protective film can be reduced as compared with the case where the transparent protective film is provided on both sides. However, the alkali metal salts described in Patent Documents 1 to 3, particularly lithium-organic anions such as lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), are applied to the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer as ionic compounds. When a salt is blended, when the polarizing film with the pressure-sensitive adhesive layer is exposed to a humidified environment, a new problem has arisen in which the antistatic function of the pressure-sensitive adhesive layer is lowered. On the other hand, when an organic cation (onium) -anionic salt is blended in the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer, the polarizer deteriorates when the polarizing film with the pressure-sensitive adhesive layer is exposed to a humid environment. Therefore, there is a problem that so-called color loss occurs and the degree of polarization decreases.

Further, when the content of the ionic compound in the pressure-sensitive adhesive layer is increased in order to improve the antistatic function of the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer becomes cloudy and the transparency is lowered. There is also a problem that the optical characteristics of the polarizing film with an adhesive layer are deteriorated.

An object of the present invention is to provide a polarizing film with an adhesive layer, which has an antistatic function and a degree of polarization that does not easily decrease even when exposed to a humid environment, and has excellent transparency.

Another object of the present invention is to provide an image display device using the polarizing film with an adhesive layer.

As a result of diligent studies to solve the above problems, the present inventors have found the following polarizing film with an adhesive layer, and have completed the present invention.

That is, the present invention is a polarizing film and a polarizing film with an adhesive layer having an adhesive layer provided on the polarizing film.
The polarizing film has a transparent protective film on only one side of the polarizer, the pressure-sensitive adhesive layer is provided on the polarizing element on the side that does not have the transparent protective film, and the pressure-sensitive adhesive layer is (meth. ) It is formed from an adhesive composition containing an acrylic polymer and an alkali metal salt.
The (meth) acrylic polymer relates to a polarizing film with an adhesive layer, which comprises a monomer (1) having a nitrogen atom and a carbon-carbon double bond as a monomer unit.

When the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer is mixed with an alkali metal salt such as a lithium-organic anion salt, the present inventors adhere to the polarizing film with the pressure-sensitive adhesive layer when exposed to a humid environment. Since the alkali metal salt shows a strong interaction with iodine in the polarizer as a cause of the deterioration of the antistatic function of the agent layer, when the pressure-sensitive adhesive layer is exposed to a humid environment, the alkali metal salt in the pressure-sensitive adhesive layer is polarized. It was thought that this was because the adhesive layer moved to the child side and was unevenly distributed, which increased the surface resistance value of the pressure-sensitive adhesive layer. Then, by using a (meth) acrylic polymer in which a monomer (1) having a nitrogen atom and a carbon-carbon double bond is introduced by copolymerization as the base polymer of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is placed in a humid environment. It has been found that the antistatic function is less likely to deteriorate even when exposed. The following can be considered as the reason. A (meth) acrylic polymer in which a monomer (1) having a nitrogen atom and a carbon-carbon double bond is introduced by copolymerization interacts with an alkali metal salt, so that the alkali metal salt in the pressure-sensitive adhesive layer becomes a polarizer. It is considered that the increase in the surface resistance value of the pressure-sensitive adhesive layer was suppressed because it became difficult to move to the side and the uneven distribution on the polarizer side was suppressed.

Further, since the (meth) acrylic polymer in which the monomer (1) having a nitrogen atom and the carbon-carbon double bond is introduced by copolymerization has a polar group, the compatibility with the alkali metal salt is improved, and the compatibility with the alkali metal salt is improved. Even when the content of the alkali metal salt is increased, the pressure-sensitive adhesive layer is less likely to become cloudy, and the transparency of the pressure-sensitive adhesive layer is less likely to decrease. Thereby, the deterioration of the optical characteristics of the polarizing film with the pressure-sensitive adhesive layer can be suppressed.

Further, when an organic cation (onium) -anion salt is blended in the pressure-sensitive adhesive layer, the binding energy between the organic cation (onium) and the iodine anion in the polarizer is low, so that the interaction between them is small. Therefore, when the polarizing film with the pressure-sensitive adhesive layer is exposed to a humidified environment, iodine in the polarizer tends to flow out to the outside (inside the pressure-sensitive adhesive). As a result, it is considered that the polarizer deteriorates and the degree of polarization decreases. By blending an alkali metal salt in the pressure-sensitive adhesive layer of the polarizing film with a pressure-sensitive adhesive layer, the present inventors make it difficult for the polarizer to deteriorate even when the polarizing film with a pressure-sensitive adhesive layer is exposed to a humid environment. It was found that the degree of polarization is less likely to decrease. The following can be considered as the reason. Since the bond energy between the alkali metal cation and the iodine anion in the polarizer is high, their interaction becomes large, and the alkali metal cation stabilizes the iodine complex in the polarizer at the interface between the pressure-sensitive adhesive layer and the polarizer. .. As a result, even when the polarizing film with the pressure-sensitive adhesive layer is exposed to a humidified environment, iodine in the polarizer is less likely to flow out to the outside (inside the pressure-sensitive adhesive). As a result, it is considered that the polarizer is less likely to deteriorate and the degree of polarization is less likely to decrease.

The alkali metal in the alkali metal salt preferably has a bond energy of 50 kcal / mol or more with the ^{iodine anion (I −), and is more preferably lithium.}

The monomer (1) preferably has an amide group. Further, the monomer (1) preferably has a heterocycle containing a nitrogen atom.

The (meth) acrylic polymer preferably contains the monomer (1) in an amount of 0.1 to 10% by weight as a monomer unit.

The pressure-sensitive adhesive composition preferably contains 0.01 to 5 parts by weight of an alkali metal salt with respect to 100 parts by weight of the (meth) acrylic polymer.

The rate of change (A) between the surface resistance value (B) after storing the pressure-sensitive adhesive layer in a humidified environment of 60 ° C./90% RH for 500 hours and the surface resistance value (A) before storing in the humidified environment (A). B × 100 / A) is preferably 700% or less.

Further, the pressure-sensitive adhesive layer preferably has a surface resistance value (A) of 1.0 × 10 ¹¹ Ω / □ or less before being stored in the humidified environment.

In the polarizing film with an adhesive layer, a polarizing film having a thickness of 12 μm or less can be used.

Further, the polarizing film with an adhesive layer has a degree of polarization (B) after being stored in a humidified environment of 60 ° C./90% RH for 500 hours and a degree of polarization (A) before being stored in the humidified environment. The amount of change (AB) is preferably within 0.05.

The present invention also relates to an image display device characterized in that at least one polarizing film with an adhesive layer is used.

The pressure-sensitive adhesive layer of the polarizing film with a pressure-sensitive pressure-sensitive adhesive layer of the present invention contains a (meth) acrylic polymer in which a monomer (1) having a nitrogen atom and a carbon-carbon double bond is copolymerized and an alkali metal salt. By using these in combination, a polarizing film with an adhesive layer, which has an antistatic function and a degree of polarization that does not easily decrease even when exposed to a humid environment, and has excellent transparency can be obtained. The effect of the present invention is highest when the monomer (1) is a monomer having an amide group and a heterocycle containing a nitrogen atom, and the alkali metal in the alkali metal salt is lithium. ..

The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the polarizing film with a pressure-sensitive adhesive layer of the present invention contains a (meth) acrylic polymer as a base polymer. The (meth) acrylic polymer usually contains an alkyl (meth) acrylate as a main component as a monomer unit. In addition, (meth) acrylate means acrylate and / or methacrylate, and has the same meaning as (meth) of the present invention.

Examples of the alkyl (meth) acrylate constituting the main skeleton of the (meth) acrylic polymer include linear or branched alkyl groups having 1 to 18 carbon atoms. For example, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, an amyl group, a hexyl group, a cyclohexyl group, a heptyl group, a 2-ethylhexyl group, an isooctyl group, a nonyl group and a decyl group. Examples thereof include a group, an isodecyl group, a dodecyl group, an isomyristyl group, a lauryl group, a tridecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group and the like. These can be used alone or in combination. The average number of carbon atoms of these alkyl groups is preferably 3 to 9.

The weight ratio of the alkyl (meth) acrylate is preferably 70% by weight or more in terms of the weight ratio of all the constituent monomers (100% by weight) constituting the (meth) acrylic polymer as a monomer unit. The weight ratio of alkyl (meth) acrylates can be thought of as the balance of nitrogen-containing monomers and other copolymerized monomers. It is preferable to set the weight ratio of the alkyl (meth) acrylate in the above range in order to ensure the adhesiveness.

In order to exhibit the effects of the present invention, a monomer (1) having a nitrogen atom and a carbon-carbon double bond is introduced into the (meth) acrylic polymer by copolymerization.

The monomer (1) is a compound containing a nitrogen atom in its structure and containing a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Examples of the monomer (1) include maleimide-based monomers such as maleimide, N-cyclohexyl maleimide, and N-phenylmaleimide; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexa. Succinimide-based monomers such as methylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2- Itaconimide-based monomers such as ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide; cyano (meth) acrylate-based monomers such as acryloylnitrile and methacrylonitrile; aminoethyl (meth) acrylate, amino (meth) acrylate. Aminoalkyl (meth) acrylicate monomers such as propyl, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, 3- (3-pyrinidyl) propyl (meth) acrylate; (Meta) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropylacrylamide, N-methyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hexyl ( Meta) acrylamide, N-methylol (meth) acrylamide, N-methylol-N-propane (meth) acrylamide, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, mercaptomethyl (meth) acrylamide, mercaptoethyl (meth) (Meta) acrylamide-based monomers such as acrylamide; N- (meth) acryloyl group-containing heterocyclic monomers such as N- (meth) acryloyl morpholine, N- (meth) acryloyl piperidine, N- (meth) acryloyl pyrrolidine; N-( N- (meth) acryloyl group-containing lactam-based monomers such as meta) acryloyl pyrrolidone, N- (meth) acryloyl piperidone, N- (meth) acryloyl-ε-caprolactam; N-vinylpyloyl group, N-vinylpiperidone, N-vinyl N-vinyl group-containing lactam-based monomers such as -ε-caprolactam; vinylpyloyl group, vinyl piperidine, vinyl pyridine, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrol, vinyl Examples thereof include heterocyclic-containing vinyl monomers such as imidazole, vinyl oxazole, and vinyl morpholine. These can be used alone or in combination. Of these, amide group-containing monomers such as (meth) acrylamide-based monomers, N- (meth) acryloyl group-containing heterocyclic monomers, N- (meth) acryloyl group-containing lactam-based monomers, and N-vinyl group-containing lactam-based monomers. Is more preferable, and more preferably an N- (meth) acryloyl group-containing lactam-based monomer, an N-vinyl group-containing lactam-based monomer and other lactam-based monomers, and even more preferably an N-vinyl group-containing lactam-based monomer. be.

The weight ratio of the monomer (1) is such that when the pressure-sensitive adhesive layer is exposed to a humid environment, the polarizing film with the pressure-sensitive adhesive layer is placed in a humid environment from the viewpoint of suppressing an increase in the surface resistance value of the pressure-sensitive adhesive layer. From the viewpoint of suppressing a decrease in the degree of polarization when exposed, and from the viewpoint of maintaining the transparency of the pressure-sensitive adhesive layer even when the content of the alkali metal salt in the pressure-sensitive adhesive layer is increased, 0.1 to 10 weights by weight. %, More preferably 1 to 5% by weight, still more preferably 1 to 3% by weight. When the weight ratio of the nitrogen-containing monomer is less than 0.1% by weight, the surface resistance value of the pressure-sensitive adhesive layer tends to increase when the pressure-sensitive adhesive layer is exposed to a humid environment, or the surface resistance value of the pressure-sensitive adhesive layer tends to increase in the pressure-sensitive adhesive layer. When the content of the alkali metal salt is increased, the transparency of the pressure-sensitive adhesive layer tends to decrease. On the other hand, when the weight ratio of the nitrogen-containing monomer exceeds 10% by weight, the degree of polarization tends to decrease or the reworkability tends to decrease when the polarizing film with an adhesive layer is exposed to a humid environment. ..

One or more of the (meth) acrylic polymers having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group for the purpose of improving adhesiveness and heat resistance. The copolymerization monomer of can be introduced by copolymerization. Specific examples of such a copolymerization monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6 (meth) acrylate. Hydroxyl group-containing monomers such as −hydroxyhexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methylacrylate. (Meta) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and other carboxyl group-containing monomers; Maleic anhydride, itaconic anhydride and other acid anhydrides Material group-containing monomer; (meth) acrylate alkyl-based monomer such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate; styrene sulfonic acid, allyl sulfonic acid, sulfopropyl (meth) acrylate, (meth) Examples thereof include sulfonic acid group-containing monomers such as acryloyloxynaphthalene sulfonic acid; and phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate.

Further, as the modified monomer, a vinyl-based monomer such as vinyl acetate, vinyl propionate, styrene, α-methylstyrene; an epoxy group-containing acrylic monomer such as glycidyl (meth) acrylate; ) Glycol-based acrylic ester monomers such as polypropylene glycol acrylate, methoxyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) Acrylic acid ester-based monomers such as acrylate can also be used. Further, isoprene, butadiene, isobutylene, vinyl ether and the like can be mentioned.

Further, as a copolymerizable monomer other than the above, a silane-based monomer containing a silicon atom and the like can be mentioned. Examples of the silane-based monomer include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinyloctyltrimethoxysilane. , 8-Vinyloctyloxydecyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane and the like.

Examples of the copolymerization monomer include tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, and neo. Pentyl glycol di (meth) acrylate, trimethyl propantri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate Polyfunctional monomers having two or more unsaturated double bonds such as (meth) acryloyl groups such as esterified products of (meth) acrylic acid and polyhydric alcohol, vinyl groups, polyester, epoxy, urethane, etc. Polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, etc. to which two or more unsaturated double bonds such as (meth) acryloyl group and vinyl group are added as functional groups similar to the monomer component are added to the skeleton. It can also be used.

Among these copolymerizable monomers, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferably used from the viewpoint of adhesiveness and durability. A hydroxyl group-containing monomer and a carboxyl group-containing monomer can be used in combination. These copolymerizable monomers serve as reaction points with the cross-linking agent when the pressure-sensitive adhesive composition contains the cross-linking agent. Since the hydroxyl group-containing monomer and the carboxyl group-containing monomer are highly reactive with the intermolecular cross-linking agent, they are preferably used for improving the cohesiveness and heat resistance of the obtained pressure-sensitive adhesive layer. The hydroxyl group-containing monomer is preferable in terms of reworkability, and the carboxyl group-containing monomer is preferable in terms of achieving both durability and reworkability.

When a hydroxyl group-containing monomer is contained as the copolymerization monomer, the proportion thereof is preferably 0.01 to 15% by weight, more preferably 0.03 to 10% by weight, and further preferably 0.05 to 7% by weight. .. When a carboxyl group-containing monomer is contained as the copolymerization monomer, the proportion thereof is preferably 0.05 to 10% by weight, more preferably 0.1 to 8% by weight, and further preferably 0.2 to 6% by weight. ..

As the (meth) acrylic polymer of the present invention, those having a weight average molecular weight in the range of 500,000 to 3,000,000 are usually used. Considering durability, particularly heat resistance, it is preferable to use one having a weight average molecular weight of 700,000 to 2.7 million. Further, it is preferably 800,000 to 2.5 million. If the weight average molecular weight is less than 500,000, it is not preferable in terms of heat resistance. Further, when the weight average molecular weight is larger than 3 million, a large amount of diluting solvent is required to adjust the viscosity for coating, which is not preferable because it increases the cost. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

For the production of such a (meth) acrylic polymer, known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations can be appropriately selected. Further, the obtained (meth) acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer and the like.

In solution polymerization, for example, ethyl acetate, toluene and the like are used as the polymerization solvent. As a specific example of solution polymerization, the reaction is carried out under an inert gas stream such as nitrogen, a polymerization initiator is added, and usually at about 50 to 70 ° C. under reaction conditions of about 5 to 30 hours.

The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. The weight average molecular weight of the (meth) acrylic polymer can be controlled by the amount of the polymerization initiator and the chain transfer agent used, and the reaction conditions, and the amount of the (meth) acrylic polymer used is appropriately adjusted according to these types.

Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, and 2,2'-azobis [2- (5-methyl-2). -Imidazoline-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutylamidine), 2,2 Azo-based initiators such as ´-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (manufactured by Wako Pure Chemical Industries, Ltd., VA-057), persulfates such as potassium persulfate and ammonium persulfate. , Di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylper Oxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di (4) Peroxides such as -methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) cyclohexane, t-butylhydroperoxide, hydrogen peroxide, etc. Examples thereof include an initiator, a combination of persulfate and sodium hydrogen sulfite, and a redox-based initiator that combines a peroxide and a reducing agent such as a combination of peroxide and sodium ascorbate, but the present invention is limited to these. It's not something.

The polymerization initiator may be used alone or in combination of two or more, but the total content is 0.005 to 1 part by weight with respect to 100 parts by weight of the monomer. It is preferably about 0.02 to 0.5 parts by weight, and more preferably about 0.02 to 0.5 parts by weight.

In order to produce the (meth) acrylic polymer having the weight average molecular weight by using, for example, 2,2'-azobisisobutyronitrile as the polymerization initiator, the amount of the polymerization initiator used is a monomer. It is preferably about 0.06 to 0.2 parts by weight, more preferably about 0.08 to 0.175 parts by weight, based on 100 parts by weight of the total amount of the components.

Examples of the chain transfer agent include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglucolate, 2,3-dimercapto-1-propanol and the like. The chain transfer agent may be used alone or in combination of two or more, but the total content is 0.1 part by weight with respect to 100 parts by weight of the total amount of the monomer components. It is below the degree.

Examples of the emulsifier used in the case of emulsifying polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, ammonium polyoxyethylene alkyl ether sulfate, and sodium polyoxyethylene alkyl phenyl ether sulfate, and polyoxy. Examples thereof include nonionic emulsifiers such as ethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene-polyoxypropylene block polymer. These emulsifiers may be used alone or in combination of two or more.

Further, as an emulsifier into which a radically polymerizable functional group such as a propenyl group or an allyl ether group has been introduced as a reactive emulsifier, specifically, for example, Aqualon HS-10, HS-20, KH-10, BC-05. , BC-10, BC-20 (all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Adecaria Soap SE10N (manufactured by Asahi Denko Co., Ltd.) and the like. Since the reactive emulsifier is incorporated into the polymer chain after polymerization, it has good water resistance and is preferable. The amount of the emulsifier used is more preferably 0.3 to 5 parts by weight and 0.5 to 1 part by weight from the viewpoint of polymerization stability and mechanical stability with respect to 100 parts by weight of the total amount of the monomer components.

The pressure-sensitive adhesive composition of the present invention contains an alkali metal salt in addition to the (meth) acrylic polymer.

As the alkali metal salt, an organic salt and an inorganic salt of the alkali metal can be used.

Examples of the alkali metal ion constituting the cation portion of the alkali metal salt include each ion such as lithium, sodium and potassium. The alkali metal ion has a bond energy of 50 kcal / mol or more with the ^{iodine anion (I −} ) from the viewpoint of increasing the interaction with the iodine anion in the polarizer and stabilizing the iodine complex in the polarizer. It is preferably 70 kcal / mol or more, more preferably 85 kcal / mol or more, and particularly preferably 105 kcal / mol or more. From the above viewpoint, among alkali metal ions, ^{lithium ion having a binding energy with iodine anion (I −} ) of 140.8 kcal / mol is preferable. Further, when the monomer (1) introduced into the (meth) acrylic polymer by copolymerization is basic, when the (meth) acrylic polymer comes into contact with the polarizer, the polarizer deteriorates, and the polarizer deteriorates. Color loss is likely to occur. However, when the alkali metal ion constituting the cation part of the alkali metal salt is a lithium ion, the iodine complex in the polarizer can be stabilized, so that the color loss of the polarizer can be effectively suppressed. Can be done.

The anion portion of the alkali metal salt may be composed of an organic substance or an inorganic substance. The anion portion is preferably bulky in order to prevent the alkali metal salt in the pressure-sensitive adhesive layer from moving to the polarizer side. Examples of the anion portion constituting the organic salt include CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , C ₄ F ₉ SO ₃ ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ ) (CF ₃ CO) N ⁻ , ⁻ O ₃ S (CF ₂ ) ₃ SO ₃ ⁻ , PF ₆ ⁻ , CO ₃ ^2- 1) to (4),
(1): (C _n F _{2n + 1} SO ₂ ) ₂ N ⁻ (where n is an integer of 1 to 10),
(2): CF ₂ (C _m F _{2 m} SO ₂ ) ₂ N ⁻ (where m is an integer of 1 to 10),
(3): ⁻ O ₃ S (CF ₂ ) _l SO ₃ ⁻ (where l is an integer of 1 to 10),
(4): (C _p F _{2p + 1} SO ₂ ) N ⁻ (C _q F _{2q + 1} SO ₂ ), (where p and q are integers of 1 to 10), and the like are used. In particular, the anion portion containing a fluorine atom is preferably used because an ionic compound having good ionic dissociation property can be obtained. The anion portions constituting the inorganic salt include Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , AsF ₆ ⁻ , and SbF. ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , (CN) ₂ N ⁻ , etc. are used. As the anion portion, as described above, from the viewpoint that a bulky one is preferable, the general formula (1) such as _{(CF 3} SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ^{−, etc.} The (perfluoroalkylsulfonyl) imide represented is preferred, especially the (trifluoromethanesulfonyl) imide represented by (CF ₃ SO ₂ ) ₂ N ⁻ .

Specific examples of the organic salt of the alkali metal include sodium acetate, sodium alginate, sodium lignin sulfonate, sodium toluene sulfonate, LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, and Li (CF ₃ SO _2). ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (C ₄ F ₉ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C, KO ₃ S (CF ₂ ) ₃ SO ₃ K, _{LiO 3 S (CF 2) 3} SO 3 K , and the like, among these _{LiCF 3 SO 3, Li (CF} 3 SO 2) 2 N, Li (C 2 F 5 SO 2) 2 N, Li (C 4 F ₉ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C and the like are preferable, and Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (C ₄ F ₉ SO) ₂₎ fluorine-containing lithium imide salt is more preferred, such as 2 _N, in particular (perfluoroalkyl sulfonyl) imide lithium salts are preferred.

Examples of the inorganic salt of the alkali metal include lithium perchlorate and lithium iodide.

The content of the alkali metal salt in the pressure-sensitive adhesive composition of the present invention is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer in order to obtain the effects of the present invention. , More preferably 0.1 to 4.5 parts by weight, still more preferably 0.5 to 4 parts by weight. When the content of the alkali metal salt is less than 0.01 parts by weight, it becomes difficult to impart an antistatic function to the pressure-sensitive adhesive layer. On the other hand, when the content of the alkali metal salt exceeds 5 parts by weight, the pressure-sensitive adhesive layer tends to become cloudy even when the (meth) acrylic polymer is used, and the transparency of the pressure-sensitive adhesive layer tends to decrease. ..

The pressure-sensitive adhesive composition of the present invention contains a known organic cation (onium) -anion salt (for example, those described in JP-A-2014-048497) as long as the effects of the present invention are not impaired. You may.

Furthermore, the pressure-sensitive adhesive composition of the present invention can contain a cross-linking agent. As the cross-linking agent, an organic cross-linking agent or a polyfunctional metal chelate can be used. Examples of the organic cross-linking agent include isocyanate-based cross-linking agents, peroxide-based cross-linking agents, epoxy-based cross-linking agents, and imine-based cross-linking agents. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinated to an organic compound. Examples of the polyvalent metal atom include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti and the like. Can be mentioned. Examples of the atom in the organic compound having a covalent bond or a coordination bond include an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound.

As the cross-linking agent, an isocyanate-based cross-linking agent and / or a peroxide-type cross-linking agent is preferable. Examples of the compound related to the isocyanate-based cross-linking agent include isocyanate monomers such as tolylene diisocyanate, chlorphenylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate, and these isocyanate monomers. Examples include isocyanate compounds added with trimetylolpropane and the like, isocyanurates, bullet-type compounds, and urethane prepolymer-type isocyanates which have been subjected to an addition reaction such as polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, and polyisoprene polyols. be able to. Particularly preferred is a polyisocyanate compound, which is one selected from the group consisting of hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate, or a polyisocyanate compound derived thereto. Here, one selected from the group consisting of hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate or a polyisocyanate compound derived thereto includes hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and polyol modification. Hexamethylene diisocyanate, polyol-modified hydrogenated xylylene diisocyanate, trimmer-type hydrogenated xylylene diisocyanate, polyol-modified isophorone diisocyanate and the like are included. The exemplified polyisocyanate compound is particularly preferable because the reaction with the hydroxyl group proceeds rapidly by using the acid and the base contained in the polymer as a catalyst, which contributes to the speed of cross-linking.

As the peroxide, any peroxide that generates radically active species by heating or light irradiation to promote cross-linking of the base polymer of the pressure-sensitive adhesive composition can be appropriately used, but in consideration of workability and stability. It is preferable to use a peroxide having a half-life temperature of 80 ° C. to 160 ° C. for 1 minute, and more preferably to use a peroxide having a half-life temperature of 90 ° C. to 140 ° C.

Examples of the peroxide that can be used include di (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6 ° C.) and di (4-t-butylcyclohexyl) peroxydicarbonate (1). Minute half-life temperature: 92.1 ° C., di-sec-butylperoxydicarbonate (1 minute half-life temperature: 92.4 ° C.), t-butylperoxyneodecanoate (1 minute half-life temperature: 103) .5 ° C.), t-hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C.), t-butyl peroxypivalate (1 minute half-life temperature: 110.3 ° C.), dilauroyl peroxide (1 minute half-life temperature: 110.3 ° C.) 1 minute half temperature: 116.4 ° C), di-n-octanoyl peroxide (1 minute half temperature: 117.4 ° C), 1,1,3,3-tetramethylbutylperoxy-2-ethyl Hexanoate (1 minute half-life temperature: 124.3 ° C.), di (4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2 ° C.), dibenzoyl peroxide (1 minute half-life temperature: 130. 0 ° C.), t-Butylperoxyisobutyrate (1 minute half-life temperature: 136.1 ° C.), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.) And so on. Among them, di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.) and dilauroyl peroxide (1 minute half-life temperature: 116.) Since the cross-linking reaction efficiency is particularly excellent. 4 ° C.), dibenzoylperoxide (1 minute half-life temperature: 130.0 ° C.) and the like are preferably used.

The half-life of peroxide is an index showing the decomposition rate of peroxide, and means the time until the residual amount of peroxide is halved. The decomposition temperature for obtaining a half-life at an arbitrary temperature and the half-life time at an arbitrary temperature are described in the manufacturer's catalog, etc. For example, "Organic Peroxide Catalog 9th Edition" of Nippon Oil & Fats Co., Ltd. (May 2003) ”and so on.

The amount of the cross-linking agent used is preferably 0.01 to 20 parts by weight, more preferably 0.03 to 10 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer. If the amount of the cross-linking agent is less than 0.01 parts by weight, the cohesive force of the adhesive tends to be insufficient and foaming may occur during heating. On the other hand, if the amount is more than 20 parts by weight, the moisture resistance is not sufficient. Peeling is likely to occur in reliability tests and the like.

The isocyanate-based cross-linking agent may be used alone or in combination of two or more, but the content as a whole is 100 parts by weight of the (meth) acrylic polymer. On the other hand, the polyisocyanate compound cross-linking agent is preferably contained in an amount of 0.01 to 2 parts by weight, more preferably 0.02 to 2 parts by weight, and preferably 0.05 to 1.5 parts by weight. It is more preferable to do so. It can be appropriately contained in consideration of cohesive force, prevention of peeling in durability test, and the like.

One type of the peroxide may be used alone, or two or more types may be mixed and used, but the content as a whole is based on 100 parts by weight of the (meth) acrylic polymer. , The peroxide is 0.01 to 2 parts by weight, preferably 0.04 to 1.5 parts by weight, and more preferably 0.05 to 1 part by weight. It is appropriately selected within this range in order to adjust workability, reworkability, crosslink stability, peelability and the like.

As a method for measuring the amount of peroxide decomposition remaining after the reaction treatment, for example, HPLC (high performance liquid chromatography) can be used.

More specifically, for example, about 0.2 g of the pressure-sensitive adhesive composition after the reaction treatment is taken out, immersed in 10 ml of ethyl acetate, extracted by shaking at 120 rpm for 3 hours at 25 ° C. with a shaker, and then at room temperature. Let stand for 3 days. Next, 10 ml of acetonitrile was added, and the mixture was shaken at 120 rpm at 25 ° C. for 30 minutes, and about 10 μl of the extract obtained by filtering with a membrane filter (0.45 μm) was injected into HPLC for analysis. It can be the amount of peroxide.

Further, the pressure-sensitive adhesive composition of the present invention may contain a silane coupling agent. Durability can be improved by using a silane coupling agent. Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3, 4-Epylcyclohexyl) Epyl group-containing silane coupling agents such as ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl- Amino group-containing silane coupling agents such as N- (1,3-dimethylbutylidene) propylamine, N-phenyl-γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltri Examples thereof include a (meth) acrylic group-containing silane coupling agent such as ethoxysilane, and an isocyanate group-containing silane coupling agent such as 3-isocyanuppropyltriethoxysilane.

The silane coupling agent may be used alone or in combination of two or more, but the content as a whole is as described above with respect to 100 parts by weight of the (meth) acrylic polymer. The silane coupling agent is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 1 part by weight, further preferably 0.02 to 1 part by weight, and further preferably 0.05 to 0.6 parts by weight. Is preferable. It is an amount that improves durability and appropriately retains adhesive force to optical members such as liquid crystal cells.

Further, the pressure-sensitive adhesive composition of the present invention may contain a polyether-modified silicone compound. As the polyether-modified silicone compound, for example, those disclosed in JP-A-2010-275522 can be used.

The polyether-modified silicone compound has a polyether skeleton and has at least one terminal at the following general formula (1): -SiR _a M _3-a.
(In the formula, R is a monovalent organic group having 1 to 20 carbon atoms which may have a substituent, M is a hydroxyl group or a hydrolyzable group, and a is an integer of 0 to 2. However, when there are a plurality of Rs, the plurality of Rs may be the same or different from each other, and when there are a plurality of Ms, the plurality of Ms may be the same or different from each other.) It has a reactive silyl group represented.

The polyether-modified silicone compound includes
General formula (2): R _a M _3-a Si-XY- (AO) _n- Z
(In the formula, R is a monovalent organic group having 1 to 20 carbon atoms which may have a substituent, M is a hydroxyl group or a hydrolyzable group, and a is an integer of 0 to 2. However, when there are a plurality of Rs, the plurality of Rs may be the same or different from each other, and when there are a plurality of Ms, the plurality of Ms may be the same or different from each other. , A linear or branched oxyalkylene group having 1 to 10 carbon atoms, n being 1 to 1700, indicating the average number of moles of the oxyalkylene group added. X is a linear or branched chain having 1 to 20 carbon atoms. The alkylene group of the branched chain is shown. Y represents an ether bond, an ester bond, a urethane bond, or a carbonate bond.
Z is a hydrogen atom, a hydrocarbon group having 1 to 10 monovalent carbon atoms,
General formula (2A): -Y ^1- X-SiR _a M _3-a
(In the equation, R, M, X are the same as above. Y ¹ indicates a single bond, -CO- bond, -CONH- bond, or -COO- bond.) Or.
General formula (2B): -Q {-(OA) _n- Y-X-SiR _a M _3-a } _m
(In the formula, R, M, X, Y are the same as above. OA is the same as AO, n is the same as above. Q is a hydrocarbon group having 2 or more valences and having 1 to 10 carbon atoms. , M is the same as the valence of the hydrocarbon group). ) Is mentioned.

Specific examples of the polyether-modified silicone compound include MS polymers S203, S303, S810; SILYL EST250, EST280; SAT10, SAT200, SAT220, SAT350, SAT400 manufactured by Kaneka Corporation, and EXCESTAR S2410, S2420 or S3430 manufactured by Asahi Glass Co., Ltd. And so on.

Further, the pressure-sensitive adhesive composition of the present invention may contain other known additives, for example, a polyether compound of a polyalkylene glycol such as polypropylene glycol, a colorant, a powder such as a pigment, a dye, and the like. Surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, antioxidants, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metals It can be appropriately added depending on the intended use of powder, particulate, foil or the like. Further, a redox system to which a reducing agent is added may be adopted within a controllable range.

A pressure-sensitive adhesive layer is formed by the pressure-sensitive adhesive composition. In forming the pressure-sensitive adhesive layer, it is necessary to adjust the amount of the entire cross-linking agent added and to fully consider the effects of the cross-linking treatment temperature and the cross-linking treatment time. preferable.

The cross-linking treatment temperature and the cross-linking treatment time can be adjusted depending on the cross-linking agent used. The crosslinking treatment temperature is preferably 170 ° C. or lower.

Further, the cross-linking treatment may be performed at the temperature at the time of the drying step of the pressure-sensitive adhesive layer, or a separate cross-linking treatment step may be provided after the drying step.

The cross-linking treatment time can be set in consideration of productivity and workability, but is usually about 0.2 to 20 minutes, preferably about 0.5 to 10 minutes.

In the polarizing film with an adhesive layer of the present invention, a transparent protective film is provided only on one side of the polarizer, and the pressure-sensitive adhesive layer is provided on the polarizing element by the pressure-sensitive adhesive composition without providing a transparent protective film on the other side. It is formed.

As a method of forming the pressure-sensitive adhesive layer, for example, a method of applying the pressure-sensitive adhesive composition to a peeled separator or the like, drying and removing a polymerization solvent or the like to form a pressure-sensitive adhesive layer, and then transferring the pressure-sensitive adhesive composition to a polarizing film, or a method of transferring the pressure-sensitive adhesive layer to a polarizing film. It is produced by a method of applying the pressure-sensitive adhesive composition to a polarizing film and drying and removing a polymerization solvent or the like to form a pressure-sensitive adhesive layer on the polarizing film. When applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be newly added as appropriate.

A silicone release liner is preferably used as the release-treated separator. In the step of applying the adhesive composition of the present invention on such a liner and drying it to form a pressure-sensitive adhesive layer, as a method of drying the pressure-sensitive adhesive, an appropriate method is appropriately adopted depending on the purpose. obtain. 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 in the above range, a pressure-sensitive adhesive having excellent adhesive properties can be obtained.

As the drying time, an appropriate time can be adopted as appropriate. 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.

Further, an anchor layer can be formed on the surface of the polarizing film, or an adhesive layer can be formed after various easy-adhesion treatments such as corona treatment and plasma treatment are performed. Further, the surface of the pressure-sensitive adhesive layer may be subjected to an easy-adhesion treatment.

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 include a method such as 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. It is preferably 2 to 50 μm, more preferably 2 to 40 μm, and even more preferably 5 to 35 μm.

The rate of change (A) between the surface resistance value (B) after storing the pressure-sensitive adhesive layer in a humidified environment of 60 ° C./90% RH for 500 hours and the surface resistance value (A) before storing in the humidified environment (A). B × 100 / A) is preferably 700% or less, more preferably 500% or less, still more preferably 400% or less, still more preferably 300% or less.

Further, the surface resistance value (A) of the pressure-sensitive adhesive layer before being stored in the humidified environment ^{is preferably 1.0 × 10 11} Ω / □ or less, more preferably 8.0 × 10 ¹⁰ Ω. It is / □ or less, and more preferably 5.0 × 10 ¹⁰ Ω / □ or less.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected by a sheet (separator) that has been peeled off until it is put into practical use.

Examples of the constituent material of the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film, porous materials such as paper, cloth, and non-woven fabric, nets, foam sheets, metal foils, and laminates thereof. A thin leaf body or the like can be mentioned, 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, and for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, and vinyl chloride are all 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. If necessary, the separator may be used for mold release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agent, silica powder, etc., as well as a coating type, a kneading type, and a vapor deposition type. It is also possible to perform antistatic treatment such as. In particular, the peelability from the pressure-sensitive adhesive layer can be further enhanced by appropriately performing a peeling treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the separator.

The peeled sheet used in producing the above-mentioned polarizing film with an adhesive layer can be used as it is as a separator for the polarizing film with an adhesive layer, and the process can be simplified.

As the polarizing film, a polarizing film having a transparent protective film on only one side of the polarizing element is used.

The polarizer is not particularly limited, and various polarizers can be used. Examples of the polarizer include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene / vinyl acetate copolymer system partially saponified film, and a bicolor property of iodine or a bicolor dye. Examples thereof include a uniaxially stretched film by adsorbing a substance, a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrogenated product of polyvinyl chloride. Among these, a polarizer made of a polyvinyl alcohol-based 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 in which a polyvinyl alcohol-based film is dyed with iodine and uniaxially stretched can be prepared, for example, by dyeing the polyvinyl alcohol-based film by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times the original length. 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-based film may be immersed in water and washed with water before dyeing. In addition to being able to clean the surface of the polyvinyl alcohol film and blocking inhibitors by washing the polyvinyl alcohol film with water, it also has the effect of preventing non-uniformity such as uneven dyeing by swelling the polyvinyl alcohol film. be. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching and then dyeing with iodine. It can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

The thickness of the polarizer is preferably 12 μm or less, more preferably 10 μm or less, still more preferably 8 μm or less, still more preferably 7 μm or less, and particularly preferably 6 μm, from the viewpoint of thinning and suppressing the occurrence of so-called through cracks. It is as follows. On the other hand, the thickness of the polarizer is preferably 2 μm or more, more preferably 3 μm or more. Such a thin polarizing element has less uneven thickness, excellent visibility, and less dimensional change, so that it has excellent durability against thermal shock.

Typical examples of the thin polarizing element include JP-A-51-069644, JP-A-2000-338329, WO2010 / 100917 pamphlet, PCT / JP2010 / 00146, or Japanese Patent Application No. 2010-. Examples thereof include the thin polarizing layer described in the specification of No. 269002 and the specification of Japanese Patent Application No. 2010-263692. These thin polarizing layers can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter, also referred to as PVA-based resin) layer and a resin base material for stretching 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 because it is supported by the stretching resin base material.

The thin polarizing layer can be stretched at a high magnification and the polarization performance can be improved even in a manufacturing method including a step of stretching in a laminated state and a step of dyeing. It is preferably obtained by a production method including a step of stretching in an aqueous boric acid solution as described in JP2010 / 00460, or in Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692, particularly preferably. It is preferably obtained by a production method including a step of auxiliary stretching in the air before stretching in the boric acid aqueous solution described in Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692.

The thin and high-performance polarizing layer described in the above description of PCT / JP2010 / 00160 is a thin thin resin having a thickness of 7 μm or less and made of a PVA-based resin in which a dichroic substance is oriented, which is integrally formed on a resin base material. It is a high-performance polarizing layer and has optical characteristics such as a single transmittance of 42.0% or more and a degree of polarization of 99.95% or more.

In the thin and high-performance polarizing layer, a PVA-based resin layer is formed by applying and drying a PVA-based resin on a resin base material having a thickness of at least 20 μm, and the generated PVA-based resin layer is used as a dyeing solution for a bicolor substance. The PVA-based resin layer on which the bicolorous substance is adsorbed is adsorbed on the PVA-based resin layer by immersing in It can be produced by stretching it so as to be 5 times or more of.

Further, it is a method for producing a laminated film including a thin and highly functional polarizing layer in which a bicolor substance is oriented, and contains a resin base material having a thickness of at least 20 μm and a PVA-based resin on one side of the resin base material. The laminate containing a step of producing a laminate film containing a PVA-based resin layer formed by applying and drying an aqueous solution, and a PVA-based resin layer formed on one side of the resin base material and the resin base material. A step of adsorbing a bicolor substance on a PVA-based resin layer contained in a laminated film by immersing the film in a dyeing solution containing a bicolor substance, and a PVA-based resin adsorbing the bicolor substance. The step of stretching the laminated film containing the layer so that the total draw ratio is 5 times or more of the original length in the boric acid aqueous solution, and the PVA-based resin layer on which the bicolor substance is adsorbed are the resin base material. The thickness is 7 μm or less, the single permeability is 42.0% or more, and the degree of polarization is 99. The thin and highly functional polarizing layer can be produced by including the step of producing a laminated film obtained by forming a thin and highly functional polarizing layer having an optical characteristic of .95% or more.

In the present invention, as described above, in the polarizing film with the pressure-sensitive adhesive layer, the polarizing layer is a continuous web polarizing layer made of a PVA-based resin in which a dichroic substance is oriented as a polarizer having a thickness of 12 μm or less. A laminate obtained by stretching a laminate containing a polyvinyl alcohol-based resin layer formed on a plastic resin base material in a two-step stretching step consisting of aerial auxiliary stretching and boric acid water stretching can be used. As the thermoplastic resin base material, an amorphous ester-based thermoplastic resin base material or a crystalline ester-based thermoplastic resin base material is preferable.

The thin polarizing layer of Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692 is a continuous web polarizing layer made of a PVA-based resin in which a dichroic substance is oriented, and is amorphous. The laminate containing the PVA-based resin layer formed on the ester-based thermoplastic resin base material was stretched in a two-step stretching step consisting of aerial auxiliary stretching and boric acid water stretching to obtain a thickness of 12 μm or less. It is a thing. In such a thin polarizing layer, when the simple substance transmittance is T and the degree of polarization is P, P> − (10 ^{0.929 T-42.4} -1) × 100 (where T <42.3), and P ≧ It is preferable that the material has optical characteristics that satisfy the condition of 99.9 (however, T ≧ 42.3).

Specifically, the thin polarizing layer is a stretching intermediate composed of a PVA-based resin layer oriented by high-temperature stretching in the air with respect to a PVA-based resin layer formed on a continuous web amorphous ester-based thermoplastic resin base material. Colored intermediate formation consisting of a PVA-based resin layer in which a dichroic substance (preferably iodine or a mixture of iodine and an organic dye) is oriented by a step of producing a product and adsorption of the dichroic substance to the stretching intermediate product. A thin polarizing layer including a step of forming a product and a step of forming a polarizing layer having a thickness of 12 μm or less composed of a PVA-based resin layer in which a dichroic substance is oriented by stretching in boric acid with respect to a colored intermediate product. It can be manufactured by the manufacturing method of.

In this production method, the total draw ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin base material by high-temperature stretching in the air and stretching in water boric acid is set to 5 times or more. desirable. The liquid temperature of the boric acid aqueous solution for stretching boric acid in water can be 60 ° C. or higher. Before stretching the colored intermediate product in the boric acid aqueous solution, it is desirable to insolubilize the colored intermediate product. In that case, the colored intermediate product is added to the boric acid aqueous solution whose liquid temperature does not exceed 40 ° C. It is desirable to do this by immersing. The amorphous ester-based thermoplastic resin base material is an amorphous polyethylene containing copolymerized polyethylene terephthalate copolymerized with isophthalic acid, copolymerized polyethylene terephthalate copolymerized with cyclohexanedimethanol, or other copolymerized polyethylene terephthalate. It can be made of terephthalate, preferably made of a transparent resin, and its thickness can be 7 times or more the thickness of the PVA-based resin layer to be formed. The stretching ratio of the high-temperature stretching in the air is preferably 3.5 times or less, and the stretching temperature of the high-temperature stretching in the air is preferably equal to or higher than the glass transition temperature of the PVA-based resin, specifically in the range of 95 ° C to 150 ° C. When high-temperature stretching in the air is performed by free-end uniaxial stretching, the total stretching ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin base material is preferably 5 times or more and 7.5 times or less. .. Further, when high-temperature stretching in the air is performed by uniaxial stretching at a fixed end, the total stretching ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin base material is 5 times or more and 8.5 times or less. Is preferable.
More specifically, the thin polarizing layer can be manufactured by the following method.

A continuous web substrate of isophthalic acid copolymerized polyethylene terephthalate (amorphous PET) obtained by copolymerizing 6 mol% of isophthalic acid is prepared. The glass transition temperature of amorphous PET is 75 ° C. A laminate composed of an amorphous PET base material of a continuous web and a polyvinyl alcohol (PVA) layer is prepared as follows. Incidentally, the glass transition temperature of PVA is 80 ° C.

A 200 μm-thick amorphous PET substrate and a 4 to 5% concentrated PVA aqueous solution prepared by dissolving PVA powder having a degree of polymerization of 1000 or more and a degree of saponification of 99% or more in water are prepared. Next, a PVA aqueous solution is applied to a 200 μm-thick amorphous PET base material and dried at a temperature of 50 to 60 ° C. to obtain a laminate in which a 7 μm-thick PVA layer is formed on the amorphous PET base material. ..

A thin, high-performance polarizing layer having a thickness of 3 μm is produced from a laminate containing a PVA layer having a thickness of 7 μm through the following steps including a two-step stretching step of auxiliary stretching in the air and stretching in boric acid in water. By the first-stage aerial auxiliary stretching step, the laminated body containing the PVA layer having a thickness of 7 μm is stretched integrally with the amorphous PET substrate to produce a stretched laminated body containing the PVA layer having a thickness of 5 μm. Specifically, this stretched laminate is subjected to a stretching device equipped in an oven set to a stretching temperature environment of 130 ° C. to obtain a stretching ratio of 1.8 times. It is stretched uniaxially at the free end. By this stretching treatment, the PVA layer contained in the stretched laminate is changed into a 5 μm-thick PVA layer in which PVA molecules are oriented.

Next, the dyeing step produces a colored laminate in which iodine is adsorbed on a 5 μm-thick PVA layer in which PVA molecules are oriented. Specifically, in this colored laminate, the stretched laminate is mixed with a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30 ° C., and the single transmittance of the PVA layer constituting the highly functional polarizing layer finally produced is obtained. Iodine is adsorbed on the PVA layer contained in the stretched laminate by immersing it for an arbitrary time so that the content is 40 to 44%. In this step, the dyeing solution uses water as a solvent and has an iodine concentration in the range of 0.12 to 0.30% by weight and a potassium iodide concentration in the range of 0.7 to 2.1% by weight. The ratio of iodine to potassium iodide concentrations is 1: 7. By the way, potassium iodide is required to dissolve iodine in water. More specifically, by immersing the stretched laminate in a dyeing solution having an iodine concentration of 0.30% by weight and a potassium iodide concentration of 2.1% by weight for 60 seconds, iodine is applied to a 5 μm-thick PVA layer in which PVA molecules are oriented. To produce a colored laminate in which iodine is adsorbed.

Further, by the second step of stretching in boric acid in water, the colored laminate is further stretched integrally with the amorphous PET substrate to generate an optical film laminate containing a PVA layer constituting a highly functional polarizing layer having a thickness of 3 μm. do. Specifically, this optical film laminate is stretched by subjecting the colored laminate to a stretching device installed in a processing device set in a boric acid aqueous solution having a liquid temperature range of 60 to 85 ° C. containing boric acid and potassium iodide. It is stretched uniaxially at the free end so that the magnification is 3.3 times. More specifically, the liquid temperature of the boric acid aqueous solution is 65 ° C. It also has a boric acid content of 4 parts by weight with respect to 100 parts by weight of water and a potassium iodide content of 5 parts by weight with respect to 100 parts by weight of water. In this step, the colored laminate having an adjusted iodine adsorption amount is first immersed in a boric acid aqueous solution for 5 to 10 seconds. After that, the colored laminate is passed as it is between a plurality of sets of rolls having different peripheral speeds, which is a stretching device deployed in the processing device, and the stretching ratio is freely increased to 3.3 times over 30 to 90 seconds. Stretch uniaxially. By this stretching treatment, the PVA layer contained in the colored laminate is changed into a 3 μm-thick PVA layer in which the adsorbed iodine is highly oriented in one direction as a polyiodine ion complex. This PVA layer constitutes a highly functional polarizing layer of an optical film laminate.

Although not an essential step in the production of the optical film laminate, the optical film laminate was taken out from the boric acid aqueous solution by the cleaning step and adhered to the surface of the 3 μm-thick PVA layer formed on the amorphous PET substrate. It is preferable to wash boric acid with an aqueous solution of potassium iodide. After that, the washed optical film laminate is dried by a drying step with warm air at 60 ° C. The cleaning step is a step for eliminating appearance defects such as boric acid precipitation.

Similarly, although it is not an essential process for producing an optical film laminate, an adhesive is applied to the surface of a 3 μm-thick PVA layer formed on an amorphous PET substrate by a bonding and / or transfer process. However, after laminating a (meth) acrylic resin film having a lactone ring structure with a thickness of 40 μm, the amorphous PET base material is peeled off, and a 3 μm thick PVA layer is formed with a (meth) acrylic having a lactone ring structure with a thickness of 40 μm. It can also be transferred to a resin film.

[Other processes]
The method for producing the thin polarizing layer may include other steps in addition to the above steps. Examples of other steps include an insolubilization step, a cross-linking step, a drying (adjustment of water content) step, and the like. Other steps can be performed at any suitable timing.
The insolubilization step is typically performed by immersing a PVA-based resin layer in an aqueous boric acid solution. By applying the insolubilization treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 part by weight to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilizing bath (boric acid aqueous solution) is preferably 20 ° C to 50 ° C. Preferably, the insolubilization step is performed after the laminate is prepared and before the dyeing step and the underwater stretching step.
The above-mentioned cross-linking step is typically performed by immersing a PVA-based resin layer in an aqueous boric acid solution. Water resistance can be imparted to the PVA-based resin layer by subjecting it to a cross-linking treatment. The concentration of the boric acid aqueous solution is preferably 1 part by weight to 4 parts by weight with respect to 100 parts by weight of water. Further, when the cross-linking step is performed after the dyeing step, it is preferable to further add iodide. By blending iodide, the elution of iodine adsorbed on the PVA-based resin layer can be suppressed. The blending amount of iodide is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. Specific examples of iodide are as described above. The liquid temperature of the crosslinked bath (boric acid aqueous solution) is preferably 20 ° C. to 50 ° C. Preferably, the cross-linking step is performed before the second boric acid water stretching step. In a preferred embodiment, the dyeing step, the cross-linking step, and the second boric acid water stretching step are performed in this order.

As a material constituting the transparent protective film, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyether sulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, and cyclic resins. Examples thereof include polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film may contain one or more of any suitable additives. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an antioxidant, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a coloring agent and the like. The content of the thermoplastic resin in the transparent 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 the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited.

A transparent protective film is attached to one side of the polarizer by an adhesive layer. An adhesive is used for the bonding process between the polarizer and the transparent protective film. Examples of the adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, and water-based polyesters. The adhesive is usually used as an adhesive consisting of an aqueous solution, and usually contains 0.5 to 60% by weight of a solid content. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include an ultraviolet curable adhesive and an electron beam curable adhesive. The adhesive for an electron beam curable polarizing film exhibits suitable adhesiveness to the above-mentioned various transparent protective films. Further, the adhesive used in the present invention may contain a metal compound filler.

Further, the polarizing film can be laminated with another optical film. Other optical films include, for example, for forming liquid crystal display devices such as reflectors, antitransparent plates, retardation films (including wave plates such as 1/2 and 1/4), visual compensation films, and brightness improving films. Examples thereof include those which are optical layers that may be used. These can be laminated on the polarizing film in practical use and used as one layer or two or more layers.

The optical film in which the optical layer is laminated on the polarizing film can also be formed by a method of sequentially and separately laminating in the manufacturing process of a liquid crystal display device or the like, but the optical film which is laminated in advance is of good quality. It is excellent in stability and assembly work, and has an advantage that the manufacturing process of a liquid crystal display device and the like can be improved. An appropriate adhesive means such as an adhesive layer can be used for laminating. When the above-mentioned polarizing film and other optical layers are adhered to each other, their optical axes can be arranged at an appropriate arrangement angle according to a target phase difference characteristic or the like.

The polarizing film with an adhesive layer of the present invention has a degree of polarization (B) after being stored in a humidified environment of 60 ° C./90% RH for 500 hours and a degree of polarization (A) before being stored in the humidified environment. The amount of change (AB) is preferably within 0.05, more preferably within 0.04, and even more preferably within 0.03.

The polarizing film with an adhesive layer of the present invention can be preferably used for forming various image display devices such as a liquid crystal display device. 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 a display panel such as a liquid crystal cell, a polarizing film with an adhesive layer, and if necessary, components such as a lighting system, and incorporating a drive circuit. The present invention is not particularly limited except that the polarizing film with the pressure-sensitive adhesive layer according to the present invention is used, and can be the same as the conventional one. As the liquid crystal cell, any type such as TN type, STN type, π type, VA type, IPS type and the like can be used.

It is possible to form an appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing film with an adhesive layer is arranged on one side or both sides of a display panel such as a liquid crystal cell, or a lighting system using a backlight or a reflector. .. In that case, the polarizing film with an adhesive layer according to the present invention can be installed on one side or both sides of a display panel such as a liquid crystal cell. When the optical films are provided on both sides, they may be the same or different. Further, when forming the liquid crystal display device, for example, an appropriate component such as a diffusion layer, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion sheet, and a backlight is placed in one layer or at an appropriate position. Two or more layers can be arranged.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. In addition, each part and% in each example is based on weight. All the conditions left at room temperature, which are not specified below, are 23 ° C. and 65% RH.

<Measurement of weight average molecular weight of (meth) acrylic polymer>
The weight average molecular weight of the (meth) acrylic polymer was measured by GPC (gel permeation chromatography).
-Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
-Column: Made by Tosoh, G7000H _XL + GMH _XL + GMH _XL
-Column size: 7.8 mm φ x 30 cm each 90 cm in total
-Column temperature: 40 ° C
・ Flow rate: 0.8 ml / min
・ Injection amount: 100 μl
-Eluent: Tetrahydrofuran-Detector: Differential refractometer (RI)
・ Standard sample: Polystyrene

<Manufacturing of polarizing film>
(Making a polarizer)
Amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of 75 ° C. Alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization 1200, degree of acetoacetyl modification 4.6%, degree of saponification 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. , Trade name "Gosefimer Z200") at a ratio of 9: 1 was applied and dried at 25 ° C. to form a PVA-based resin layer having a thickness of 11 μm to prepare a laminate.
The obtained laminate was uniaxially stretched at the free end in the longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 30 ° C. (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, the polarizing plate 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 mixed with 100 parts by weight of water, and 1.0 part by weight of potassium iodide was mixed and immersed in the obtained iodine aqueous solution for 60 seconds (dyeing treatment). ..
Then, it was immersed in a cross-linked bath at a liquid temperature of 30 ° C. (an aqueous boric acid 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) for 30 seconds. (Crossing treatment).
Then, the laminate is immersed in an aqueous solution of boric acid having a liquid temperature of 70 ° C. (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). However, uniaxial stretching was performed between rolls having different peripheral speeds so that the total stretching ratio was 5.5 times in the longitudinal direction (longitudinal direction) (underwater stretching treatment).
Then, the laminate was immersed in a washing bath at a liquid temperature of 30 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
From the above, an optical film laminate containing a polarizer having a thickness of 5 μm and a boric acid content of 16% was obtained.

(Preparation of adhesive to be applied to transparent protective film)
An ultraviolet curable adhesive was prepared by mixing 40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloyl morpholine (ACMO), and 3 parts by weight of the photoinitiator "IRGACURE 819" (manufactured by BASF).

(Preparation of polarizing film)
While applying the ultraviolet curable adhesive to the surface of the polarizer of the optical film laminate, the easy-adhesion-treated surface of the (meth) acrylic resin film having a lactone ring structure with a thickness of 40 μm is subjected to corona treatment and then bonded. , The amorphous PET base material was peeled off to prepare a polarizing film using a thin polarizing element. Hereinafter, this is referred to as a thin polarizing film.

<Preparation of acrylic polymer (A1)>
80.3 parts of butyl acrylate, 0.5 parts of 4-hydroxybutyl acrylate, 0.2 parts of acrylic acid, N-vinylpyrrolidone in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. A monomer mixture containing 3 parts and 16 parts of phenoxyethyl acrylate was charged. Further, with respect to 100 parts of the monomer mixture (solid content), 0.15 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator was charged together with ethyl acetate, and nitrogen gas was introduced while gently stirring. After the nitrogen substitution, the liquid temperature in the flask was maintained at around 60 ° C. and the polymerization reaction was carried out for 7 hours. Then, ethyl acetate was added to the obtained reaction solution to prepare a solution of an acrylic polymer (A1) having a weight average molecular weight of 1.4 million adjusted to a solid content concentration of 30%.

<Preparation of acrylic polymers (A2) to (A12)>
In the preparation of the acrylic polymer (A1), solutions of the acrylic polymers (A2) to (A12) were prepared in the same manner except that the composition of the monomers was changed as shown in Table 1 and the polymerization conditions were adjusted. ..

Example 1
(Preparation of adhesive composition)
One part of lithium bis (trifluoromethanesulfonyl) imide (manufactured by Mitsubishi Materials Electronics Co., Ltd.) was added to 100 parts of the solid content of the obtained acrylic polymer (A1) solution, and trimethylolpropane hexamethylene diisocyanate (trimethylolpropanehexamethylene diisocyanate) was further added. Mitsui Chemicals, trade name "Takenate D-160N") 0.17 parts, dibenzoyl peroxide 0.25 parts, silane coupling agent (Shin-Etsu Chemicals, trade name "X-41-1810") 0 An acrylic pressure-sensitive adhesive solution was prepared by blending 2 parts by weight and 0.2 parts by weight of an acetoacetyl group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "A-100").

(Preparation of polarizing film with adhesive layer)
Next, the above-mentioned acrylic pressure-sensitive adhesive solution was uniformly applied to the surface of a polyethylene terephthalate film (separator film) treated with a silicone-based release agent with a fountain coater, and dried in an air circulation type constant temperature oven at 155 ° C. for 1 minute. Then, a pressure-sensitive adhesive layer having a thickness of 20 μm was formed on the surface of the separator film. Next, the pressure-sensitive adhesive layer formed on the separator film was transferred to the side of the polarizing layer of the polarizer of the thin polarizing film prepared above to prepare a polarizing film with a pressure-sensitive adhesive layer.

Examples 2-9, Comparative Examples 1-4
In Example 1, a polarizing film with an adhesive layer was prepared in the same manner as in Example 1 except that the type or amount of each component was changed as shown in Table 1 in preparing the pressure-sensitive adhesive composition. ..

The following evaluations were performed on the polarizing films with an adhesive layer obtained in the above Examples and Comparative Examples. The evaluation results are shown in Table 1.

<Measurement of change in degree of polarization>
The separator film of the polarizing film with the adhesive layer was peeled off and attached to microslide glass (manufactured by Matsunami Glass Co., Ltd., trade name "S200") using a laminator. Next, an autoclave treatment was performed at 50 ° C. and 0.5 MPa for 15 minutes to completely adhere the polarizing film with the pressure-sensitive adhesive layer to the non-acrylic glass. Then, it was stored for 500 hours in a humidified environment at 60 ° C./90% RH. The degree of polarization of the polarizing film before and after storage was measured using V7100 manufactured by JASCO Corporation. The amount of change in the degree of polarization was calculated by the following formula and evaluated according to the following criteria.
Amount of change ΔP = (polarization degree before storage)-(polarization degree after storage)
(Evaluation criteria)
⊚: 0 ≦ ΔP <0.02
〇: 0.02 ≤ ΔP <0.04
Δ: 0.04 ≦ ΔP <0.05
X: 0.05 ≦ ΔP

<Measurement of change rate of surface resistance value>
After peeling off the separator film of the polarizing film with the pressure-sensitive adhesive layer, the surface resistance value (Ω / □) of the pressure-sensitive adhesive surface was measured using MCP-HT450 manufactured by Mitsubishi Chemical Analytech. Further, even after the polarizing film with the pressure-sensitive adhesive layer was stored in a humidified environment of 60 ° C./90% RH for 500 hours, the surface resistance value of the pressure-sensitive adhesive surface was measured in the same manner as described above. The rate of change (%) of the surface resistance value was calculated by the following formula and evaluated according to the following criteria.
Rate of change ΔR (%) = (surface resistance value after storage) × 100 / (surface resistance value before storage)
(Evaluation criteria)
⊚: 0 ≦ ΔR <300
〇: 300 ≤ ΔR <500
Δ: 500 ≦ ΔR <700
X: 700 ≦ ΔR

<Measurement of haze>
After peeling off the separator film of the polarizing film with an adhesive layer, haze (%) of the polarizing film with an adhesive layer is determined using a haze meter (HN-150, manufactured by Murakami Color Science Laboratory) by the method specified by JIS 7136. It was measured. The haze of the polarizing film with the pressure-sensitive adhesive layer is preferably 3% or less, more preferably 1% or less.

The compounds in Table 1 are as follows.
BA: Butyl acrylate 4HBA: 4-Hydroxybutyl acrylate AA: Acrylic acid NVP: N-vinylpyrrolidone ACMO: N-acryloylmorpholine MMA: Methyl methacrylate PEA: Phenoxyethyl acrylate LiTFSi: Lithiumbis (trifluoromethanesulfonyl) imide (Mitsubishi Materials Electronics) Made by Kaseisha)
EMPTFSi: Ethylmethylpyrrolidinium-bis (trifluoromethanesulfonyl) imide (manufactured by Tokyo Chemical Industry)

The polarizing film with an adhesive layer of the present invention is used in an image display device such as a liquid crystal display device (LCD) or an organic EL display device as an optical film which is used alone or in a laminated manner.

Claims (10)

A polarizing film with a pressure-sensitive adhesive layer having a polarizing film and a pressure-sensitive adhesive layer provided on the polarizing film.
The polarizing film has a transparent protective film on only one side of the polarizer, the pressure-sensitive adhesive layer is provided on the polarizing element on the side that does not have the transparent protective film, and the pressure-sensitive adhesive layer is (meth. ) It is formed from an adhesive composition containing an acrylic polymer and an alkali metal salt.
The (meth) acrylic polymer contains a monomer (1) having a nitrogen atom and a carbon-carbon double bond as a monomer unit .
The monomer (1) is a lactam-based monomer and is
Alkali metals, iodine anion in the alkali metal salt (I ^-) and a polarizing film pressure-sensitive adhesive layer bond energy is characterized der Rukoto than 50 kcal / mol of. The polarizing film with an adhesive layer according to claim 1, wherein the lactam-based monomer is an N-vinyl group-containing lactam-based monomer. The polarizing film with an adhesive layer according to claim 1 or 2, wherein the alkali metal in the alkali metal salt is lithium. The polarizing film with an adhesive layer according to any one of claims 1 to 3 , wherein the (meth) acrylic polymer contains 0.1 to 10% by weight of the monomer (1) as a monomer unit. .. The adhesive according to any one of claims 1 to 4 , wherein the pressure-sensitive adhesive composition contains 0.01 to 5 parts by weight of an alkali metal salt with respect to 100 parts by weight of the (meth) acrylic polymer. Alkali film with agent layer. The rate of change (A) between the surface resistance value (B) after storing the pressure-sensitive adhesive layer in a humidified environment of 60 ° C./90% RH for 500 hours and the surface resistance value (A) before storing in the humidified environment (A). The polarizing film with an adhesive layer according to any one of claims 1 to 5 , wherein B × 100 / A) is 700% or less. The polarized light with an adhesive layer according to claim 6 , wherein the pressure-sensitive adhesive layer has a surface resistance value (A) of 1.0 × 10 ¹¹ Ω / □ or less before being stored in the humidified environment. the film. The polarizing film with an adhesive layer according to any one of claims 1 to 7 , wherein the polarizing element has a thickness of 12 μm or less. The amount of change in the degree of polarization (B) of the polarizing film with an adhesive layer after being stored in a humidified environment of 60 ° C./90% RH for 500 hours and the degree of polarization (A) before being stored in the humidified environment. The polarizing film with an adhesive layer according to any one of claims 1 to 8 , wherein (AB) is within 0.05. An image display device using at least one polarizing film with an adhesive layer according to any one of claims 1 to 9.