Polarizing film with adhesive layer and image display device

Abstract

The present invention relates to an adhesive layer-equipped polarizing film and an image display device. The present invention aims to provide an adhesive layer-equipped polarizing film that can solve the problem of reduced yield and that can impart sufficient ultraviolet blocking function even when the polarizing film is thin. In addition, the present invention also aims to provide an image display device that uses the adhesive layer-equipped polarizing film. An adhesive layer-equipped polarizing film that is used in an image display device at a position closer to the visually recognizing side than the image display portion, characterized by having a polarizing film and adhesive layers on both sides of the polarizing film, the polarizing film having a polarizer and transparent protective films on both sides of the polarizer, the transparent protective film on the visually recognizing side of the polarizer having a transmittance of 6% or more at a wavelength of 380 nm, and the adhesive layer on the visually recognizing side of the polarizing film having ultraviolet absorbing function.

Description

[0001] This application is a divisional application of Chinese patent application No. 201680086276.3, filed on June 15, 2016, entitled "Polarizing Film with Adhesive Layer and Image Display Device". Technical Field

[0002] This invention relates to a polarizing film with an adhesive layer used in image display devices. Furthermore, this invention relates to image display devices using the aforementioned polarizing film with an adhesive layer. Examples of image display devices include: liquid crystal displays, organic EL (electroluminescent) displays, PDP (plasma display panels), and electronic paper. Background Technology

[0003] For liquid crystal displays (LCDs) and organic EL displays, due to their image formation methods, such as in LCDs where polarizing elements are placed on both sides of the liquid crystal cells, polarizing films are typically attached. In addition to polarizing films, various optical components are used in display panels such as LCD and EL panels to improve display quality.

[0004] The polarizing films used in these image display devices typically have a configuration where the polarizer is sandwiched between two protective films, and triacetyl cellulose (TAC) is widely used as the protective film.

[0005] In recent years, with the trend towards lightweighting and thin-film technology in image display devices, there has been a demand for thinner materials for various components used in these devices, including the protective film for polarizing films. However, when the thickness of this protective film decreases, it becomes insufficient to block ultraviolet (UV) radiation incident on the image display device. This not only accelerates UV-induced degradation of the polarizer but also accelerates UV-induced degradation of various optical components, including the liquid crystal panel and organic EL elements used in the image display device.

[0006] To eliminate such problems, for example, there are known materials such as: a transparent double-sided adhesive sheet for an image display device, wherein the double-sided adhesive sheet is disposed between a surface protection panel and the visual recognition side of a liquid crystal module in the image display device for integrating the two components, wherein the double-sided adhesive sheet has at least one ultraviolet absorbing layer, a light transmittance of less than 30% at a wavelength of 380 nm, and a visible light transmittance of more than 80% at a wavelength closer to the longer wavelength side than 430 nm (for example, see Patent Document 1); and an adhesive sheet having an adhesive layer containing an acrylic polymer and a triazine ultraviolet absorber (for example, see Patent Document 2). Furthermore, it is known that in adhesive-type optical films where an adhesive layer is provided on one or both sides of an optical film, the adhesive layer can be endowed with ultraviolet absorption capability (for example, see Patent Document 3).

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2012-211305

[0010] Patent Document 2: Japanese Patent Application Publication No. 2013-75978

[0011] Patent Document 3: Japanese Patent No. 4208187 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] In recent years, as described in Patent Documents 1 to 3, it has been known to use transparent adhesives with ultraviolet absorption capabilities to bond various components used in image display devices. However, this results in uneven thickness or poor yield, which poses a problem from an operational point of view.

[0014] Therefore, an object of the present invention is to provide a polarizing film with an adhesive layer that can solve the problem of reduced yield and provide sufficient ultraviolet blocking function even when the polarizing film is thin. Furthermore, an object of the present invention is to provide an image display device using the aforementioned polarizing film with an adhesive layer.

[0015] means for solving problems

[0016] In order to solve the aforementioned problem, the inventors conducted repeated and in-depth research and discovered the following polarizing film with an adhesive layer, thus completing the present invention.

[0017] That is, the present invention relates to a polarizing film with an adhesive layer, which is used in an image display device at a location closer to the visual recognition side than the image display section.

[0018] Its features are,

[0019] The polarizing film with adhesive layer has a polarizing film and adhesive layers on both sides of the polarizing film.

[0020] The polarizing film has a polarizer and transparent protective films on both sides of the polarizer.

[0021] The transparent protective film on the visual recognition side of the polarizer has a transmittance of over 6% at a wavelength of 380nm, and

[0022] The adhesive layer on the visual recognition side of the polarizing film has ultraviolet absorption function.

[0023] Preferably, the transparent protective film on the visual recognition side of the polarizer is at least one film selected from the group consisting of triacetyl cellulose film, acrylic film, polyethylene terephthalate film, and polyolefin film having a cyclic or norbornene structure, and the thickness of the transparent protective film on the visual recognition side of the polarizer is less than 40 μm.

[0024] Preferably, the thickness of the adhesive layer on the visual recognition side of the polarizing film is more than twice the thickness of the adhesive layer on the image display side of the polarizing film.

[0025] Preferably, the transmittance of the adhesive layer on the visual recognition side of the polarizing film at a wavelength of 380 nm is less than 40%, and the transmittance of the adhesive layer on the visual recognition side of the polarizing film at a wavelength of 400 nm is more than 30%.

[0026] Preferably, the b* value of the adhesive layer on the visual recognition side of the polarizing film is 3.0 or less.

[0027] Preferably, the adhesive layer on the visual recognition side of the polarizing film contains an acrylic polymer as the base polymer.

[0028] The polarizing film with adhesive layer of the present invention is preferably used in liquid crystal display devices or organic EL display devices.

[0029] In addition, the present invention relates to an image display device, characterized in that the polarizing film with adhesive layer is used in a portion closer to the visual recognition side than the image display portion.

[0030] Invention Effects

[0031] The polarizing film with an adhesive layer of the present invention is configured such that an adhesive layer with ultraviolet absorption function is pre-laminated on the visual recognition side of the polarizing film. Therefore, it reduces the number of processes, solves the problem of low yield, and provides sufficient ultraviolet blocking function even when the polarizing film is thin. Furthermore, since the image display device of the present invention uses the aforementioned polarizing film with an adhesive layer, it can suppress ultraviolet-induced degradation of various optical components, including liquid crystal panels and organic EL elements used in the image display device. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view schematically illustrating one embodiment of the polarizing film with an adhesive layer according to the present invention.

[0033] Figure 2 This is a cross-sectional view schematically illustrating one embodiment of the image display device of the present invention.

[0034] Figure 3 This is a cross-sectional view schematically illustrating one embodiment of the image display device of the present invention.

[0035] Figure 4 This is a cross-sectional view schematically illustrating one embodiment of the image display device of the present invention. Detailed Implementation

[0036] 1. Polarizing film with adhesive layer

[0037] The polarizing film with adhesive layer of the present invention is characterized in that,

[0038] The polarizing film with adhesive layer is used in an image display device at a location closer to the visual recognition side than the image display section.

[0039] The polarizing film with adhesive layer has a polarizing film and adhesive layers on both sides of the polarizing film.

[0040] The polarizing film has a polarizer and transparent protective films on both sides of the polarizer.

[0041] The transparent protective film on the visual recognition side of the polarizer has a transmittance of over 6% at a wavelength of 380nm, and

[0042] The adhesive layer on the visual recognition side of the polarizing film has ultraviolet absorption function.

[0043] like Figure 1 As shown, the polarizing film 1 with an adhesive layer of the present invention may be composed of a visual recognition side adhesive layer 2a, a visual recognition side transparent protective film 3a, a polarizer 4, an image display side transparent protective film 3b, and an image display side adhesive layer 2b, or it may also include a phase retardation film, etc. Specifically, it may be composed of a visual recognition side adhesive layer 2a, a visual recognition side transparent protective film 3a, a polarizer 4, an image display side transparent protective film 3b, an image display side adhesive layer 2b, a phase retardation film (not shown), and an image display side adhesive layer (not shown), etc. The polarizing film 5 is composed of a visual recognition side transparent protective film 3a, a polarizer 4, and an image display side transparent protective film 3b. Each layer will be described in detail below.

[0044] (1) Adhesive layer for visual recognition

[0045] In this invention, the adhesive layer on the visual recognition side of the polarizing film (visual recognition side adhesive layer) is characterized by having ultraviolet absorption functionality. The composition of the visual recognition side adhesive layer is not particularly limited, as long as it possesses ultraviolet absorption functionality.

[0046] Suitable adhesives can be used in the formation of the visual recognition side adhesive layer, and there are no particular limitations on their types. Examples of adhesives include: rubber-based adhesives, acrylic adhesives, polysiloxane adhesives, polyurethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, and cellulose adhesives. Among these adhesives, acrylic adhesives are preferred from the viewpoint of excellent optical transparency, appropriate adhesion, cohesiveness, and tackiness, as well as excellent weather resistance and heat resistance. The acrylic adhesive contains an acrylic polymer as its base polymer.

[0047] The visual recognition side adhesive layer using the aforementioned acrylic adhesive is preferably formed, for example, by ultraviolet polymerization of a UV-curable acrylic adhesive composition comprising: a monomeric component containing an alkyl (meth)acrylate and / or a portion of the polymer of said monomeric component, an ultraviolet absorber, and a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or higher. The adhesive layer formed by ultraviolet polymerization of the aforementioned UV-curable acrylic adhesive composition can form a thickness of 150 μm or more, and is therefore preferred as it allows for the formation of adhesive layers with a wide range of thicknesses.

[0048] Examples of alkyl (meth)acrylates include those having a straight-chain or branched alkyl group with 1 to 24 carbon atoms at the ester terminus. Alkyl (meth)acrylates can be used alone or in combination of two or more. It should be noted that alkyl (meth)acrylates refer to alkyl acrylates and / or alkyl methacrylates, and the (methyl) in this invention has the same meaning.

[0049] As for the alkyl methacrylate, examples include alkyl methacrylates having branches having 4 to 9 carbon atoms. From the perspective of easily obtaining a balance of adhesive properties, this alkyl methacrylate is preferred. Specifically, examples include: n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, isohexyl methacrylate, isohexyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, isononyl methacrylate, etc., which can be used alone or in combination of two or more.

[0050] In this invention, the alkyl methacrylate having an alkyl group having 1 to 24 carbon atoms at the ester terminus is preferably 40% by weight or more, more preferably 50% by weight or more, and even more preferably 60% by weight or more, relative to the total amount of the monofunctional monomer components forming the (meth)acrylate polymer.

[0051] The monomer composition may contain comonomers other than the alkyl methacrylate as monofunctional monomer components. These comonomers may be used as the remainder of the alkyl methacrylate in the monomer composition.

[0052] As a comonomer, for example, a cyclic nitrogen-containing monomer may be included. Among the aforementioned cyclic nitrogen-containing monomers, monomers having polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl or vinyl groups, and having a cyclic nitrogen structure, can be used without particular limitation. Preferably, the cyclic nitrogen structure contains a nitrogen atom within the cyclic structure. Examples of cyclic nitrogen-containing monomers include: N-vinylpyrrolidone, N-vinyl-ε-caprolactam, methylvinylpyrrolidone, and other lactam vinyl monomers; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazolium, vinylpyrrolidone, vinylpyrrolidone, vinylpyrazole, vinyl... Vinyl monomers containing nitrogen-containing heterocycles, such as azoles and vinylmorpholines, are examples. Additionally, (meth)acrylic acid monomers containing heterocycles such as morpholine rings, piperidine rings, pyrrolidine rings, and piperazine rings can be listed. Specifically, examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine. Among these cyclic nitrogen-containing monomers, lactam vinyl monomers are preferred.

[0053] In this invention, the cyclic nitrogen-containing monomer is preferably 0.5% to 50% by weight, more preferably 0.5% to 40% by weight, and even more preferably 0.5% to 30% by weight, relative to the total amount of the monofunctional monomer component forming the (meth)acrylic polymer.

[0054] The monomer components used in this invention may include hydroxyl-containing monomers as monofunctional monomer components. As for hydroxyl-containing monomers, monomers containing polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl or vinyl groups, and having hydroxyl groups, can be used without particular limitation. Examples of hydroxyl-containing monomers include, for instance, hydroxyalkyl esters of (meth)acrylate such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl methacrylate, 10-hydroxydecyl methacrylate, and 12-hydroxylaurate; and hydroxyalkylcycloalkyl esters of (meth)acrylate such as (4-hydroxymethylcyclohexyl)methacrylate. Furthermore, examples include hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. These hydroxyl-containing monomers can be used alone or in combination. Among them, hydroxyalkyl (meth)acrylate is preferred.

[0055] In this invention, from the perspective of improving adhesive strength and cohesiveness, the hydroxyl-containing monomer is preferably 1% by weight or more, more preferably 2% by weight or more, and even more preferably 3% by weight or more, relative to the total amount of monofunctional monomer components forming the (meth)acrylic acid polymer. On the other hand, if there is too much of the hydroxyl-containing monomer, the adhesive layer may harden and the adhesive strength may decrease. In addition, the viscosity of the adhesive may be too high or gelation may occur. Therefore, relative to the total amount of monofunctional monomer components forming the (meth)acrylic acid polymer, the hydroxyl-containing monomer is preferably 30% by weight or less, more preferably 27% by weight or less, and even more preferably 25% by weight or less.

[0056] In addition, the monomer components that form (meth)acrylic acid polymers may contain other functionalized monomers as monofunctional monomers, such as monomers containing carboxyl groups or monomers with cyclic ether groups.

[0057] As for carboxyl-containing monomers, monomers containing polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl or vinyl groups, and having carboxyl groups can be used without particular limitation. Examples of carboxyl-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylic acid, carboxypentyl (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc., which can be used alone or in combination. For itaconic acid and maleic acid, their anhydrides can be used. Among them, acrylic acid and methacrylic acid are preferred, and acrylic acid is particularly preferred. It should be noted that carboxyl-containing monomers can optionally be used in the monomer components used in the manufacture of the (meth)acrylic acid polymers of the present invention, and on the other hand, carboxyl-containing monomers may not be used.

[0058] As for monomers with cyclic ether groups, monomers containing polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl or vinyl groups, and having cyclic ether groups such as epoxy or oxetyl groups, can be used without particular limitation. Examples of epoxy-containing monomers include glycidyl (meth)acrylate, 3,4-epoxycyclohexyl methyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. Examples of oxetyl monomers include 3-oxetyl methyl (meth)acrylate, 3-methyl-3-oxetyl methyl (meth)acrylate, 3-ethyl-3-oxetyl methyl (meth)acrylate, 3-butyl-3-oxetyl methyl (meth)acrylate, and 3-hexyl-3-oxetyl methyl (meth)acrylate. These monomers with cyclic ether groups can be used alone or in combination.

[0059] In this invention, relative to the total amount of monofunctional monomer components forming (meth)acrylic acid polymers, the aforementioned carboxyl-containing monomers and monomers having cyclic ether groups are preferably 30% by weight or less, more preferably 27% by weight or less, and even more preferably 25% by weight or less.

[0060] Among the monomer components forming the (meth)acrylic acid polymers of the present invention, examples of comonomers include CH2=C(R) 1 COOR 2 (R above) 1 R represents hydrogen or methyl. 2 Alkyl methacrylates, representing substituted alkyl groups (or cyclic cycloalkyl groups) with 1 to 3 carbon atoms.

[0061] Here, as R 2 The substituent of the substituted alkyl group having 1 to 3 carbon atoms is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. There are no restrictions on the aryl group, but phenyl is preferred.

[0062] As such, CH2=C(R) 1 COOR 2 Examples of monomers that can be represented include phenoxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, and isobornyl methacrylate. These monomers can be used alone or in combination.

[0063] In this invention, relative to the total amount of monofunctional monomer components forming (meth)acrylic acid polymers, the above-mentioned CH2=C(R) 1 COOR 2The indicated (meth)acrylate can be used at 50% by weight or less, preferably 45% by weight or less, more preferably 40% by weight or less, and even more preferably 35% by weight or less.

[0064] Other comonomers that can be used include vinyl acetate, vinyl propionate, styrene, α-methylstyrene; glycol acrylate monomers such as polyethylene glycol methacrylate, polypropylene glycol methacrylate, methoxyethylene glycol methacrylate, and polypropylene glycol methacrylate; acrylate monomers such as tetrahydrofurfuryl methacrylate, fluoromethacrylate, polysiloxane methacrylate, and 2-methoxyethyl acrylate; amide-containing monomers, amino-containing monomers, imide-containing monomers, N-acryloylmorpholine, and vinyl ether monomers. Additionally, cyclic monomers such as terpene methacrylate and tetrahydrodicyclopentadienyl methacrylate can be used as comonomers.

[0065] In addition, silane monomers containing silicon atoms can be listed. Examples of silane monomers include: 3-acryloyloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, etc.

[0066] In addition to the monofunctional monomers exemplified above, the monomer components forming the (meth)acrylic polymers of the present invention may contain polyfunctional monomers as needed to adjust the cohesiveness of the adhesive.

[0067] Polyfunctional monomers are monomers having at least two polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl or vinyl groups. Examples include: ester compounds of polyols and (meth)acrylic acid, such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, etc.; allyl methacrylate, ethylene methacrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, etc. Among them, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate are preferred. One polyfunctional monomer may be used alone or in combination of two or more.

[0068] The amount of multifunctional monomers used varies depending on their molecular weight, number of functional groups, etc. It is preferable to use 3 parts by weight or less, more preferably 2 parts by weight or less, and even more preferably 1 part by weight or less, relative to a total of 100 parts by weight of monofunctional monomers. Furthermore, there are no particular limitations on the lower limit, but it is preferable to use 0 parts by weight or more, more preferably 0.001 parts by weight or more. By using multifunctional monomers within the above-mentioned range, adhesive strength can be improved.

[0069] In this invention, it may be a partial polymer of the monomer component.

[0070] There are no particular limitations on the UV absorbers included in the UV-curable acrylic adhesive composition. Examples include triazine UV absorbers, benzotriazole UV absorbers, benzophenone UV absorbers, hydroxybenzophenone UV absorbers, salicylate UV absorbers, and cyanoacrylate UV absorbers. These UV absorbers can be used alone or in combination of two or more. Among them, triazine UV absorbers and benzotriazole UV absorbers are preferred. More preferably, at least one UV absorber selected from the group consisting of a triazine UV absorber having two or fewer hydroxyl groups in one molecule and a benzotriazole UV absorber having one benzotriazole skeleton in one molecule is preferred because it has good solubility in the monomers used in the formation of the UV-curable acrylic adhesive composition and high UV absorption capacity around 380 nm.

[0071] As for triazine UV absorbers having two or fewer hydroxyl groups in one molecule, specific examples include: 2,4-bis[{4-(4-ethylhexyloxy)-4-hydroxy}phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (Tinosorb S, manufactured by BASF); 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (TINUVIN 460, manufactured by BASF); 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-hydroxyphenyl and [(C 10 -C 16 (mainly C) 12 -C 13 The reaction product of alkyloxymethyl ethylene oxide (TINUVIN 400, manufactured by BASF); 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol, the reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine with 2-ethylhexyl glycidyl acid (TINUVIN 405, manufactured by BASF); 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]phenol (TINUVIN 1577, manufactured by BASF); 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol (ADK STAB) LA46 (manufactured by ADEKA Corporation); 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN479, manufactured by BASF Corporation), etc.

[0072] In addition, examples of benzotriazole UV absorbers having a benzotriazole skeleton in one molecule include: 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (TINUVIN PS, manufactured by BASF), ester compounds of phenylpropionic acid and 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and straight-chain alkyl) (TINUVIN 384-2, manufactured by BASF); 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN 900, manufactured by BASF); 2-(2H-benzotriazole- 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF); the reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (TINUVIN 1130, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-p-cresol (TINUVIN) P (manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN234, manufactured by BASF); 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-tert-butylphenol (TINUVIN326, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN328, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TIN UVIN329 (manufactured by BASF); the reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (TINUVIN213, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-cresol (TINUVIN571, manufactured by BASF); 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidemethyl)-5-methylphenyl]benzotriazole (Sumisorb250, manufactured by Sumitomo Chemical Co., Ltd.), etc.

[0073] In addition, examples of benzophenone-based ultraviolet absorbers (benzophenone compounds) and hydroxybenzophenone-based ultraviolet absorbers (hydroxybenzophenone compounds) include: 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous salt and trihydrate salt), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4-dimethoxybenzophenone, etc.

[0074] In addition, examples of salicylate-based ultraviolet absorbers (salicylate compounds) include: phenyl 2-acryloyloxybenzoate, phenyl 2-acryloyloxy-3-methylbenzoate, phenyl 2-acryloyloxy-4-methylbenzoate, phenyl 2-acryloyloxy-5-methylbenzoate, phenyl 2-acryloyloxy-3-methoxybenzoate, phenyl 2-hydroxybenzoate, phenyl 2-hydroxy-3-methylbenzoate, phenyl 2-hydroxy-4-methylbenzoate, phenyl 2-hydroxy-5-methylbenzoate, phenyl 2-hydroxy-3-methoxybenzoate, and 2,4-di-tert-butyl-4-hydroxybenzoate (TINUVIN120, manufactured by BASF).

[0075] Examples of cyanoacrylate-based ultraviolet absorbers (cyanoacrylate compounds) include, for example, alkyl cyanoacrylate, cycloalkyl cyanoacrylate, alkoxyalkyl cyanoacrylate, alkenyl cyanoacrylate, and alkynyl cyanoacrylate.

[0076] The ultraviolet absorber can be used alone or in combination of two or more. The total content, relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer, is preferably about 0.1 to about 5 parts by weight, more preferably about 0.5 to about 3 parts by weight. By setting the amount of ultraviolet absorber within this range, the ultraviolet absorption function of the adhesive layer can be fully utilized without hindering ultraviolet polymerization, and therefore this is preferred.

[0077] The UV-curable acrylic adhesive composition used in this invention preferably contains a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or higher. When an adhesive composition contains a UV absorber, the UV light is absorbed by the absorber during UV polymerization, thus hindering sufficient polymerization. However, the UV-curable acrylic adhesive composition used in this invention has a photopolymerization initiator (A) with an absorption band at a wavelength of 400 nm or higher, therefore, despite the presence of a UV absorber, sufficient polymerization is possible.

[0078] Examples of photopolymerization initiators (A) with absorption bands above 400 nm include: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Irgacure 819, manufactured by BASF) and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (LUCIRIN TPO, manufactured by BASF).

[0079] The photopolymerization initiator (A) with an absorption band above 400 nm can be used alone or in combination of two or more.

[0080] Furthermore, there is no particular limitation on the amount of photopolymerization initiator (A) with an absorption band at wavelengths above 400 nm, but it is preferably less than the amount of ultraviolet absorber added. Relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic acid polymer, it is preferably about 0.005 parts by weight to about 1 part by weight, more preferably about 0.02 parts by weight to about 0.5 parts by weight. With the amount of photopolymerization initiator (A) added within this range, ultraviolet polymerization can proceed sufficiently, therefore it is preferred.

[0081] Furthermore, the UV-curable acrylic adhesive composition used in this invention may contain a photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm. Preferably, the photopolymerization initiator (B) does not have an absorption band at wavelengths above 400 nm. As for the photopolymerization initiator (B), there are no particular limitations as long as it generates free radicals under UV light to initiate photopolymerization and has an absorption band at a wavelength less than 400 nm; any commonly used photopolymerization initiator can be appropriately used. For example, benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-keto alcohol photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzoyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, thioxanone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, etc., can be used.

[0082] Specifically, examples of benzoin ether photopolymerization initiators include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-methyl ketone, and anisonitrile methyl ether.

[0083] Examples of acetophenone-based photopolymerization initiators include: 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl methyl ketone, 4-phenoxydichloroacetophenone, and 4-tert-butyldichloroacetophenone.

[0084] Examples of α-keto alcohol photopolymerization initiators include 2-methyl-2-hydroxyphenylacetone and 1-[4-(2-hydroxyethyl)phenyl]-2-hydroxy-2-methylpropane-1-one.

[0085] Examples of photoactive oxime photopolymerization initiators include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime.

[0086] Examples of benzoin-based photopolymerization initiators include benzoin itself.

[0087] As a benzoyl photopolymerization initiator, it includes, for example, benzoyl.

[0088] Benzophenone-based photopolymerization initiators include, for example, benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone.

[0089] Ketal photopolymerization initiators include benzoyl dimethyl ketal, etc.

[0090] Thioxanone photopolymerization initiators include, for example, thioxanone, 2-chlorothioxanone, 2-methylthioxanone, 2,4-dimethylthioxanone, isopropylthioxanone, 2,4-dichlorothioxanone, 2,4-diethylthioxanone, 2,4-diisopropylthioxanone, dodecylthioxanone, etc.

[0091] Acylphosphine oxide photopolymerization initiators include, for example, 2,4,6-trimethylbenzoyl diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0092] The aforementioned photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm can be used alone or in combination of two or more. The aforementioned photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm can be added within a range that does not impair the effects of the present invention. As for the amount added, relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic acid polymer, it is preferably about 0.005 parts by weight to about 0.5 parts by weight, more preferably about 0.02 parts by weight to about 0.1 parts by weight.

[0093] In this invention, preferably, a photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm is first added to the monomer component, and a portion of the monomer component is polymerized by irradiation with ultraviolet light to obtain a partial polymer (prepolymer composition) of the monomer component. Then, the photopolymerization initiator (A) having an absorption band at a wavelength greater than 400 nm and an ultraviolet absorber are added to the prepolymer composition to perform ultraviolet polymerization. When adding the photopolymerization initiator (A) having an absorption band at a wavelength greater than 400 nm to the partial polymer (prepolymer composition) of the monomer component obtained by partial polymerization by ultraviolet irradiation, it is preferable to dissolve the photopolymerization initiator in the monomer before adding it.

[0094] Furthermore, the UV-curable acrylic adhesive composition used in this invention may contain a silane coupling agent. The amount of the silane coupling agent is preferably 1 part by weight or less, more preferably 0.01 part by weight to 1 part by weight, and even more preferably 0.02 part by weight to 0.6 part by weight, relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer.

[0095] Examples of silane coupling agents include, for instance, epoxy-containing silane coupling agents such as 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; silane coupling agents containing (meth)acryloyl groups such as 3-acryloyloxypropyltrimethoxysilane and 3-methacryloyloxypropyltriethoxysilane; and silane coupling agents containing isocyanate groups such as 3-isocyanate-propyltriethoxysilane.

[0096] The UV-curable acrylic adhesive composition used in this invention may contain a crosslinking agent. Crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, and polysiloxane crosslinking agents. Crosslinking agents include zoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine crosslinking agents, metal chelate crosslinking agents, and peroxide crosslinking agents. One crosslinking agent can be used alone or in combination of two or more. Isocyanate-based crosslinking agents are preferred.

[0097] The crosslinking agent described above can be used alone or in combination of two or more. The content of the crosslinking agent as a whole is preferably 5 parts by weight or less, more preferably 0.01 parts by weight to 5 parts by weight, further preferably 0.01 parts by weight to 4 parts by weight, and particularly preferably 0.02 parts by weight to 3 parts by weight, relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer.

[0098] Isocyanate crosslinking agents refer to compounds that have two or more isocyanate groups in one molecule (including isocyanate regenerated functional groups that are temporarily protected by end-capping agents or polymerization). Examples of isocyanate crosslinking agents include aromatic isocyanates such as toluene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

[0099] More specifically, examples include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; aromatic diisocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, phenylenediamine diisocyanate, and polymethylene polyphenyl isocyanate; trimethylolpropane / toluene diisocyanate trimer adduct (trade name: CORONATE L, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate trimer adduct (trade name: CORONATE HL, manufactured by Nippon Polyurethane Industry Co., Ltd.); and the isocyanurate form of hexamethylene diisocyanate (trade name: CORONATE). Isocyanate adducts such as HX (manufactured by Nippon Polyurethanes Co., Ltd.), trimethylolpropane adduct of diphenylmethylene diisocyanate (trade name: D110N, manufactured by Mitsui Chemicals Co., Ltd.), trimethylolpropane adduct of hexamethylene diisocyanate (trade name: D160N, manufactured by Mitsui Chemicals Co., Ltd.); polyether polyisocyanates, polyester polyisocyanates, and their adducts with various polyols, as well as polyisocyanates obtained by multifunctionalization using isocyanurate bonds, biuret bonds, urethane bonds, etc.

[0100] In addition to the aforementioned components, the UV-curable acrylic adhesive composition used in this invention may contain appropriate additives depending on the application. Examples include: tackifiers (e.g., substances that are solid, semi-solid, or liquid at room temperature, such as rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc.); fillers such as hollow glass microspheres; plasticizers; anti-aging agents; antioxidants, etc.

[0101] In this invention, it is preferable to adjust the viscosity of the UV-curable acrylic adhesive composition to a level suitable for coating or similar operations on a substrate. The viscosity of the UV-curable acrylic adhesive composition can be adjusted, for example, by adding various polymers such as thickening additives, multifunctional monomers, or by partially polymerizing the monomer components in the UV-curable acrylic adhesive composition. It should be noted that this partial polymerization can be performed before or after adding the various polymers such as thickening additives, multifunctional monomers, etc. Since the viscosity of the UV-curable acrylic adhesive composition varies depending on the amount of additives, etc., the polymerization rate at which the monomer components in the UV-curable acrylic adhesive composition are partially polymerized cannot be uniquely determined. As a general reference, it is preferably about 20% or less, more preferably about 3% to about 20%, and even more preferably about 5% to about 15%. When the viscosity exceeds 20%, the viscosity becomes too high, making coating onto the substrate difficult.

[0102] The visual recognition side adhesive layer can be formed by applying the UV-curable acrylic adhesive composition to at least one side of a substrate and irradiating the UV-curable acrylic adhesive composition with ultraviolet light.

[0103] There are no particular limitations on the substrate used; for example, various substrates such as release films, transparent resin film substrates, or polarizing films described later can be used. When the visual recognition side adhesive layer is formed on a substrate other than the polarizing film, the visual recognition side adhesive layer can be transferred onto the polarizing film by lamination.

[0104] Examples of materials that can be used to make the release film include: resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film; porous materials such as paper, cloth, and nonwoven fabric; and suitable thin paper-like materials (thin sheets) such as mesh, foam sheets, metal foil, and their laminates. From the viewpoint of excellent surface smoothness, resin films are preferred.

[0105] Examples of resin films include: polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

[0106] The thickness of the release film is typically 5 μm to 200 μm, preferably about 5 μm to about 100 μm. The release film can also be subjected to release and anti-fouling treatments using polysiloxane-based, fluorinated, long-chain alkyl, or fatty acid amide release agents, silica powder, etc., or to antistatic treatments such as coating, kneading, or vapor deposition. In particular, by appropriately treating the surface of the release film with polysiloxane, long-chain alkyl, or fluorine treatments, the peelability from the adhesive layer can be further improved.

[0107] There are no particular limitations on the transparent resin film substrate; various transparent resin films can be used. The resin film is formed from a single layer. Examples of materials include, for instance, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins. Among these, polyester resins, polyimide resins, and polyethersulfone resins are particularly preferred.

[0108] The thickness of the membrane substrate is preferably 15 μm to 200 μm, more preferably 25 μm to 188 μm.

[0109] The method of applying the above-mentioned UV-curable acrylic adhesive composition to the above-mentioned substrate can be any known and appropriate method, such as roller coating, licking coating, gravure coating, reverse coating, roller brush coating, spraying, dip roller coating, doctor blade coating, doctor blade coating, air knife coating, curtain coating, lip die coating, or die-cutting machine, without particular limitation.

[0110] The irradiance of the ultraviolet light irradiating the UV-curable acrylic adhesive composition is preferably 5 mW / cm². 2 The above applies when the ultraviolet irradiance is less than 5 mW / cm². 2 At this time, the polymerization reaction time becomes longer, sometimes resulting in poor productivity. It should be noted that the preferred ultraviolet irradiance is 200 mW / cm². 2 The following applies when the ultraviolet irradiance is greater than 200 mW / cm². 2 At this time, the photopolymerization initiator is rapidly consumed, which can sometimes lead to polymer depletion, especially a decrease in holding power at high temperatures. Furthermore, the cumulative ultraviolet light intensity is preferably 100 mJ / cm². 2 ~5000mJ / cm 2 .

[0111] The ultraviolet lamps used in this invention are not particularly limited, but LED lamps are preferred. Compared to other ultraviolet lamps, LED lamps release less heat, thus suppressing the temperature during the polymerization of the adhesive layer. Therefore, it is possible to prevent the polymer from becoming less polymeric, prevent a decrease in the cohesive strength of the adhesive layer, and improve the holding power at high temperatures when the adhesive sheet is formed. Alternatively, multiple ultraviolet lamps can be combined. Furthermore, ultraviolet light can be irradiated intermittently, with a bright period of ultraviolet light irradiation and a dark period of no ultraviolet light irradiation.

[0112] In this invention, the final polymerization rate of the monomer components in the UV-curable acrylic adhesive composition is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0113] In this invention, the peak wavelength of the ultraviolet light irradiating the above-mentioned UV-curable acrylic adhesive composition is preferably in the range of 200 nm to 500 nm, more preferably in the range of 300 nm to 450 nm. When the peak wavelength of the ultraviolet light is greater than 500 nm, the photopolymerization initiator sometimes does not decompose and does not initiate a polymerization reaction. In addition, when the peak wavelength of the ultraviolet light is less than 200 nm, the polymer chains are sometimes cleaved, and the adhesive properties are reduced.

[0114] The reaction is inhibited by oxygen in the air. Therefore, to block oxygen, it is preferable to form a release film on the coating layer of the acrylic adhesive composition or to carry out the photopolymerization reaction under a nitrogen atmosphere. The release film described above can be cited as an example. It should be noted that when using a release film, it can be used directly as a spacer for a polarizing film with an adhesive layer.

[0115] From the viewpoint of ensuring ultraviolet absorption function, the thickness of the adhesive layer on the visual recognition side is preferably at least twice the thickness of the adhesive layer on the image display side of the polarizing film (image display side adhesive layer), more preferably at least five times, and even more preferably at least ten times. Specifically, the thickness of the adhesive layer on the visual recognition side is preferably at least 50 μm, more preferably at least 100 μm, and even more preferably at least 150 μm. There is no particular upper limit to the thickness of the adhesive layer on the visual recognition side, but it is preferably 10 mm or less. When the thickness of the adhesive layer is greater than 10 mm, ultraviolet transmission becomes difficult, the polymerization of monomer components takes time, and sometimes the productivity is poor, so it is not preferred.

[0116] Furthermore, when the UV-curable acrylic adhesive composition used in this invention contains a photopolymerization initiator (B), it is preferable to irradiate the composition containing a monomer component containing an alkyl methacrylate and the photopolymerization initiator (B) (sometimes referred to as "pre-added polymerization initiator") with ultraviolet light to form a partial polymer of the monomer component. An ultraviolet absorber and a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or higher (sometimes referred to as "post-added polymerization initiator") are then added to the partial polymer of the monomer component to produce the UV-curable acrylic adhesive composition. The polymerization rate of the partial polymer is preferably about 20% or less, more preferably about 3% to about 20%, and even more preferably about 5% to about 15%. The ultraviolet irradiation conditions are as described above.

[0117] As previously stated, when an adhesive layer is formed from an ultraviolet-curable acrylic adhesive composition containing a photopolymerization initiator (B), by performing polymerization in the two stages described above, the polymerization rate of the monomer components can be increased, and the ultraviolet absorption function of the final adhesive layer can be improved.

[0118] There is no particular limitation on the gel fraction of the adhesive layer on the visual recognition side of the present invention, but it is preferably 50% or more, more preferably 75% or more, and even more preferably 85% or more. When the gel fraction of the adhesive layer on the visual recognition side is low, the cohesion is poor; when it is too high, the adhesive strength is sometimes poor.

[0119] There are no particular limitations on the transmittance b* value of the adhesive layer on the visual recognition side, but it is preferably 3.0 or less, more preferably 1.5 or less, and even more preferably 0.5 or less. The above-mentioned b* value refers to the b* value (chromaticity) in the L*a*b* table color system of JIS Z8729, which can be measured, for example, using a spectrophotometer (product name: U4100, manufactured by Hitachi High Technology Co., Ltd.).

[0120] The transmittance of the adhesive layer on the visual recognition side at a wavelength of 380 nm is preferably 40% or less, more preferably 20% or less, and even more preferably 8% or less. With a transmittance at a wavelength of 380 nm within this range, incident ultraviolet light can be sufficiently blocked, thus suppressing the degradation of optical components, including liquid crystal panels, organic EL elements, polarizers, etc.

[0121] The transmittance of the adhesive layer on the visual recognition side at a wavelength of 400 nm is preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more. With a transmittance at a wavelength of 400 nm within this range, incident visible light can be sufficiently transmitted, and sufficient visual recognition can be ensured in the image display device; therefore, this is preferred.

[0122] (2) Adhesive layer on the image display side

[0123] There are no particular limitations on the adhesive layer (image display side adhesive layer) that serves as the image display side surface of the polarizing film. The same adhesive layer as the UV-curable acrylic adhesive composition described in detail in the vision recognition side adhesive layer can be used, or various commonly used adhesive layers can be used.

[0124] For the formation of the adhesive layer on the side surface of the image display section, any suitable adhesive can be used, and there are no particular limitations on its type. Examples of adhesives include: rubber-based adhesives, acrylic adhesives, polysiloxane adhesives, polyurethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, and cellulose adhesives. Among these adhesives, acrylic adhesives are preferred due to their excellent optical transparency, suitable adhesion, cohesiveness, and tackiness, as well as their excellent weather resistance and heat resistance.

[0125] Acrylic adhesives use acrylic polymers with alkyl (meth)acrylate monomer units as the main backbone as the base polymer. Examples of alkyl (meth)acrylates constituting the main backbone of the acrylic polymer include those used in UV-curable acrylic adhesive compositions forming the adhesive layer on the visual recognition side. Additionally, examples of comonomers or their proportions are also those used in UV-curable acrylic adhesive compositions.

[0126] The acrylic polymer can be manufactured using various known methods, such as bulk polymerization, solution polymerization, suspension polymerization, and other free radical polymerization methods. Various known free radical polymerization initiators, such as azo dyes and peroxides, can be used as initiators. The reaction temperature is typically about 50°C to about 80°C, and the reaction time is set to 1 hour to 8 hours. Solution polymerization is preferred in this manufacturing method, and ethyl acetate or toluene is typically used as the solvent for the acrylic polymer. The solution concentration is typically set to about 20% to 80% by weight.

[0127] Additionally, the adhesive may be an adhesive composition containing a crosslinking agent. Examples of crosslinking agents include those described above, with isocyanate-based crosslinking agents being particularly preferred. There are no particular limitations on the ratio of the acrylic polymer to the crosslinking agent; generally, the crosslinking agent (solid component) is preferably about 0.001 parts by weight to about 20 parts by weight, more preferably about 0.01 parts by weight to about 15 parts by weight, relative to 100 parts by weight of the acrylic polymer (solid component).

[0128] Furthermore, as needed, and without departing from the purpose of this invention, various additives such as tackifiers, plasticizers, fillers including glass fibers, glass microspheres, metal powders, and other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, and silane coupling agents can be appropriately used in the adhesive. Additionally, an adhesive layer containing microparticles that exhibits light diffusivity can also be formed. Examples of silane coupling agents include those described above.

[0129] The adhesive layer on the image display side is formed by applying the adhesive to various substrates such as polarizing films or release films and then drying it. When the adhesive layer is formed on various substrates such as release films, the adhesive layer can be transferred onto the polarizing film by lamination. The coating method of the adhesive and the various substrates can be the same as the coating method of the UV-curable acrylic adhesive composition and the same substrate.

[0130] Furthermore, the coating amount is controlled during the coating process to ensure that the formed adhesive layer reaches a specified thickness (thickness after drying). There is no particular limitation on the thickness of the adhesive layer on the image display side, but it is preferably less than 1 / 2 of the thickness of the adhesive layer on the visual recognition side, more preferably less than 1 / 5, and even more preferably less than 1 / 10. Specifically, the thickness of the adhesive layer on the image display side is preferably about 1 μm to about 100 μm, more preferably about 3 μm to about 50 μm, and even more preferably about 5 μm to about 30 μm.

[0131] When forming the adhesive layer on the image display side, the applied adhesive is dried. There are no particular limitations on the drying temperature and drying time, which can be set appropriately. For example, it is preferable to be about 80°C to about 200°C and preferably to be 0.5 minutes to 10 minutes.

[0132] If the adhesive layer is exposed on the image display side, it can be protected by a release film until actual use. It should be noted that the release film can be used directly as a spacer for a polarizing film with an adhesive layer, thereby simplifying the process.

[0133] (3) Polarizing film

[0134] The polarizing film used in this invention is characterized in that it has a polarizer and transparent protective films on both sides of the polarizer, and the transmittance of the transparent protective film on the visual recognition side of the polarizer (visual recognition side transparent protective film) at a wavelength of 380 nm is 6% or more.

[0135] (3-1) Transparent protective film for visual recognition side

[0136] The transmittance of the visual recognition-side transparent protective film used in this invention at a wavelength of 380 nm is 6% or more, preferably 10% or more, and more preferably 15% or more. There is no particular limitation on the upper limit of the transmittance at a wavelength of 380 nm, but it is preferably 90% or less, and more preferably 30% or less. With the transmittance of the visual recognition-side transparent protective film at a wavelength of 380 nm within this range, sufficient ultraviolet absorption capability can be achieved through the combination of the thinness of the visual recognition-side transparent protective film and the visual recognition-side adhesive layer (containing an ultraviolet absorber), which is therefore preferred. Even if the visual recognition-side transparent protective film does not have ultraviolet absorption capability, the ultraviolet absorption function can be sufficiently compensated by the ultraviolet absorption provided by the visual recognition-side adhesive layer; therefore, sufficient ultraviolet absorption capability is achieved as long as the transmittance at a wavelength of 380 nm is 90% or less. Furthermore, when the transmittance of the visual recognition-side adhesive layer at a wavelength of 380 nm is 40% or less, from the perspective of ultraviolet absorption capability, it is preferable that the transmittance of the visual recognition-side transparent protective film at a wavelength of 380 nm is 30% or less.

[0137] For the material forming the transparent protective film on the visual recognition side, materials with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy are preferred. Examples include: polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin); and polycarbonate polymers. Additionally, examples of polymers forming the transparent protective film include: polyethylene, polypropylene, polyolefins having cyclic or norbornene structures, ethylene-propylene copolymers, and other polyolefin polymers; vinyl chloride polymers; amide polymers such as nylon and aromatic polyamides; imide polymers; sulfone polymers, polyethersulfone polymers; polyetheretherketone polymers; polyphenylene sulfide polymers; vinyl alcohol polymers; vinylidene chloride polymers; vinyl butyral polymers; aromatic ester polymers; polyoxymethylene polymers; epoxy polymers; or blends of the above polymers. The transparent protective film can also be formed as a cured layer of thermosetting or UV-curing resins such as acrylic, polyurethane, acrylic-polyurethane, epoxy, and polysiloxane. Among these, for the visual recognition side transparent protective film, at least one film selected from the group consisting of triacetyl cellulose film, acrylic film (film using acrylic polymers), polyethylene terephthalate film, and polyolefin film having a cyclic or norbornene structure is preferred, and triacetyl cellulose film is more preferred.

[0138] There is no particular limitation on the thickness of the transparent protective film on the visual recognition side, but it is preferably 40 μm or less, more preferably 35 μm or less, and even more preferably 30 μm or less. Furthermore, there is no particular limitation on the lower limit of the thickness of the transparent protective film on the visual recognition side, but it is preferably 1 μm or more. With the thickness of the transparent protective film on the visual recognition side within the stated range, it is possible to achieve a sufficiently thin polarization film without compromising the protective function of the polarizer, and therefore this is preferred.

[0139] The polarizer and the visual recognition side protective film, described later, are preferably adhered using an aqueous adhesive or the like. Examples of aqueous adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl-type latex adhesives, waterborne polyurethane, and waterborne polyester. In addition to the above, examples of adhesives for the polarizer and the visual recognition side transparent protective film include UV-curable adhesives and electron beam-curable adhesives. Electron beam-curable polarizing film adhesives exhibit suitable adhesion to the various visual recognition side transparent protective films described above. Furthermore, the adhesives used in this invention may contain metal compound fillers.

[0140] The non-adhesive polarizer side of the transparent protective film for visual recognition can be treated with a hard coating, anti-reflection treatment, or treatment for purposes such as preventing adhesion, diffusion, or glare.

[0141] (3-2) Polarizer

[0142] There are no particular restrictions on the polarizer, and various polarizers can be used. Examples of polarizers include: polarizers obtained by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films after adsorbing dichroic substances such as iodine or dichroic dyes; and polyolefin-oriented films such as dehydrated polyvinyl alcohol products or dehydrochlorinated polyvinyl chloride products. Among these, polarizers containing a polyvinyl alcohol film and dichroic substances such as iodine are preferred. The thickness of these polarizers is not particularly limited, and is typically from about 5 μm to about 80 μm.

[0143] Polarizers obtained by dyeing polyvinyl alcohol (PVA) films with iodine and then uniaxially stretching them can be manufactured, for example, by immersing PVA in an aqueous solution of iodine for dyeing and stretching it to 3 to 7 times its original length. Alternatively, it can be immersed in an aqueous solution containing potassium iodide, such as boric acid, zinc sulfate, or zinc chloride, as needed. Furthermore, the PVA film can be washed with water before dyeing, as required. Washing the PVA film removes stains and anti-blocking agents from its surface and also prevents uneven dyeing by causing the film to swell. Stretching can be performed after dyeing with iodine, during dyeing, or after stretching. Stretching can be performed in an aqueous solution of boric acid, potassium iodide, or a water bath.

[0144] Furthermore, in this invention, a thin polarizer with a thickness of 10 μm or less can also be used. From the viewpoint of thinness, this thickness is preferably 1 μm to 7 μm. Such a thin polarizer has less thickness unevenness, excellent visual recognition, and minimal dimensional variation, thus exhibiting excellent durability. Moreover, it is preferable to achieve thinness in terms of the thickness of the polarizing film as well.

[0145] Representative examples of thin polarizers include: Japanese Patent Application Publication No. 51-069644, Japanese Patent Application Publication No. 2000-338329, International Publication No. 2010 / 100917, Japanese Patent No. 4751481, and Japanese Patent Application Publication No. 2012-073563. These thin polarizing films can be obtained by a manufacturing method comprising a step of stretching a polyvinyl alcohol resin (hereinafter also referred to as PVA resin) layer and a stretching resin substrate in a laminated state, and a dyeing step. Using this manufacturing method, even if the PVA resin layer is thin, it can be stretched without problems such as breakage due to stretching, thanks to the support of the stretching resin substrate.

[0146] Regarding the aforementioned thin polarizing film, from the perspective of improving polarization performance by stretching at a high magnification even in manufacturing methods that include stretching and dyeing processes within a laminated state, polarizing films obtained by a manufacturing method that involves stretching in a boric acid aqueous solution, as described in International Publication No. 2010 / 100917, Japanese Patent No. 4751481, and Japanese Unexamined Patent Application Publication No. 2012-073563, are preferred. In particular, polarizing films obtained by a manufacturing method that involves auxiliary stretching in air before stretching in a boric acid aqueous solution, as described in Japanese Patent No. 4751481 and Japanese Unexamined Patent Application Publication No. 2012-073563, are preferred.

[0147] (3-3) Transparent protective film on the side of the image display unit

[0148] Regarding the transparent protective film on the image display side, conventionally used transparent protective films can be appropriately used. Specifically, transparent protective films made of materials with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy are preferred. Examples include: polyester polymers such as polyethylene terephthalate or polyethylene naphthalate; cellulose polymers such as diacetyl cellulose or triacetyl cellulose; acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene or acrylonitrile-styrene copolymer (AS resin); and polycarbonate polymers. Alternatively, examples of polymers forming the aforementioned transparent protective film include polyethylene, polypropylene, polyolefins with cyclic or norbornene structures, polyolefin polymers such as ethylene-propylene copolymers, vinyl chloride polymers, amide polymers such as nylon or aromatic polyamides, imide polymers, sulfone polymers, polyethersulfone polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aromatic ester polymers, polyoxymethylene polymers, epoxy polymers, or blends of the above polymers. The transparent protective film can also be formed as a cured layer of thermosetting or UV-curing resins such as acrylics, polyurethanes, acrylic-polyurethanes, epoxy resins, and polysiloxanes.

[0149] The thickness of the protective film on the image display side can be appropriately determined. Generally, considering factors such as strength, workability, and thinness, it is about 1 μm to about 500 μm.

[0150] The polarizer and the transparent protective film on the image display side are also typically adhered using a water-based adhesive or the like. Examples of water-based adhesives include those mentioned above.

[0151] The surface of the transparent protective film on the image display side that is not bonded to the polarizer can be treated with a hard coating, anti-reflection treatment, or treatment for the purpose of preventing adhesion, diffusion, or glare.

[0152] 2. Image display device

[0153] The image display device of the present invention is characterized in that it uses the polarizing film with adhesive layer of the present invention.

[0154] As an example of a specific configuration of an image display device, for example, such as Figures 2-4 As shown,

[0155] 6. Protective glass or protective plastic / Adhesive layer on the visual recognition side 2a / Transparent protective film on the visual recognition side 3a / Polarizer 4 / Transparent protective film on the image display side 3b / Adhesive layer on the image display side 2b / Liquid crystal display device (LCD) or organic EL display device (OLED) 7 ( Figure 2 );

[0156] Protective glass or protective plastic 6 / Adhesive layer 8a / Sensor layer 9 / Adhesive layer on the visual recognition side 2a / Transparent protective film on the visual recognition side 3a / Polarizer 4 / Transparent protective film on the image display side 3b / Adhesive layer on the image display side 2b / Liquid crystal display (LCD) or organic EL display (OLED) 7 ( Figure 3 );

[0157] Protective glass or protective plastic 6 / Adhesive layer 8a / Sensor layer 9 / Adhesive layer 8b / Sensor layer 9 / Adhesive layer on the visual recognition side 2a / Transparent protective film on the visual recognition side 3a / Polarizer 4 / Transparent protective film on the image display side 3b / Adhesive layer on the image display side 2b / Liquid crystal display (LCD) or organic EL display (OLED) 7 ( Figure 4 ); In that case,

[0158] An image display device is obtained by sequentially stacking the layers. The polarizing film 1 with an adhesive layer of the present invention refers to the portion of the above-described configuration consisting of "visual recognition side adhesive layer 2a / visual recognition side transparent protective film 3a / polarizer 4 / image display side transparent protective film 3b / image display side adhesive layer 2b," and may also include a phase retardation film, etc. Furthermore, when a phase retardation film is included, specifically, the image display side adhesive layer 2b can be stacked between the liquid crystal display device (LCD) or organic EL display device (OLED) 7 via an adhesive layer. Additionally, adhesive layers and / or adhesive adhesive layers can be appropriately used in the stacking of each layer.

[0159] Examples of image display devices include liquid crystal displays, organic EL (electroluminescent) displays, PDP (plasma display panel), and electronic paper. Among these, liquid crystal displays and organic EL (electroluminescent) displays having the above-described configurations are preferred.

[0160] Example

[0161] The present invention will now be described in detail through examples, but the present invention is not limited to these examples. It should be noted that all parts and percentages in the examples are by weight. The evaluation items in the examples, etc., were measured in the manner described below.

[0162] Manufacturing Example 1 (Manufacturing of Acrylic Adhesive Composition (a-1))

[0163] In a monomer mixture consisting of 78 parts by weight of 2-ethylhexyl acrylate (2EHA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 4 parts by weight of 2-hydroxyethyl acrylate (HEA), 0.035 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name: Irgacure 184, with an absorption band in the wavelength range of 200 nm to 370 nm, manufactured by BASF) and 0.035 parts by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name: Irgacure 651, with an absorption band in the wavelength range of 200 nm to 380 nm, manufactured by BASF) were added as photopolymerization initiators. The mixture was then irradiated with ultraviolet light until the viscosity (measurement conditions: BH viscometer, No. 5 rotor, 10 rpm, measurement temperature 30 °C) was approximately 20 Pa·s, thereby obtaining a prepolymer composition (polymerization rate: 8%) obtained by partial polymerization of the above monomer components. Next, 0.15 parts by weight of hexanediol diacrylate (HDDA) and 0.3 parts by weight of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to the prepolymer composition and mixed to obtain an acrylic adhesive composition (a-1).

[0164] Manufacturing Example 2 (Manufacturing of Acrylic Adhesive Composition (a-2))

[0165] 67 parts by weight of butyl acrylate (BA), 14 parts by weight of cyclohexyl acrylate (CHA), 27 parts by weight of 4-hydroxybutyl acrylate (4HBA), 0.05 parts by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name: Irgacure 651, with an absorption band in the wavelength range of 200 nm to 380 nm, manufactured by BASF Japan) and 0.05 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name: Irgacure 184, with an absorption band in the wavelength range of 200 nm to 370 nm, manufactured by BASF Japan) as photopolymerization initiators were added to a four-necked flask and partially photopolymerized under a nitrogen atmosphere and exposed to ultraviolet light, thereby obtaining a partial polymer (monomer slurry) with a polymerization rate of 10%. Next, 0.15 parts by weight of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA) and 0.3 parts by weight of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to this polymer and mixed and subjected to ultraviolet irradiation to obtain an acrylic adhesive composition (a-2).

[0166] Manufacturing Example 3 (Manufacturing of Adhesive Layer (B-1) on the Image Display Side)

[0167] In a separable flask equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet, 95 parts of butyl acrylate, 5 parts of acrylic acid, 0.2 parts of azobisisobutyronitrile (azobisisobutyronitrile) as a polymerization initiator, and 233 parts of ethyl acetate were added. Nitrogen gas was then introduced, and nitrogen purging was carried out for approximately 1 hour while stirring. The flask was then heated to 60°C, and the reaction was carried out for 7 hours to obtain an acrylic polymer with a weight-average molecular weight (Mw) of 1.1 million.

[0168] An adhesive composition (solution) was prepared by adding 0.8 parts by weight of trimethylolpropane toluene diisocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Kogyo Co., Ltd.) as an isocyanate crosslinking agent and 0.1 parts by weight of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) to the above acrylic polymer solution (with the solid component set at 100 parts by weight).

[0169] The obtained adhesive composition solution was applied to a 38 μm thick spacer (a polyethylene terephthalate film with a peel-off surface) to achieve a dry thickness of 12 μm. The solvent was removed by drying at 100°C for 3 minutes, thus obtaining an adhesive layer. Then, crosslinking was performed by heating at 50°C for 48 hours. Hereinafter, this adhesive layer will be referred to as the "image display side adhesive layer (B-1)".

[0170] Manufacturing Example 4 (Manufacturing of the Adhesive Layer (B-2) on the Image Display Side)

[0171] The obtained adhesive composition solution was applied to a 38 μm thick separator (a polyethylene terephthalate film with a release agent on the surface) to achieve a dry thickness of 15 μm. The solvent was removed by drying at 100°C for 3 minutes, thus obtaining an adhesive layer. Then, crosslinking was performed by heating at 50°C for 48 hours. Hereinafter, this adhesive layer will be referred to as the "image display side adhesive layer (B-2)".

[0172] Example 1

[0173] (Preparation of adhesive compositions with UV absorption function)

[0174] In the obtained acrylic adhesive composition (a-1), 1.4 parts of 2,4-bis[{4-(4-ethylhexyloxy)-4-hydroxy}phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (trade name: Tinosorb S, manufactured by BASF Japan) dissolved in butyl acrylate in such a manner as to make the solid content 15% and 0.2 parts of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name: Irgacure 819, which has an absorption band in the wavelength range of 200 nm to 450 nm, manufactured by BASF Japan) were added and stirred to obtain an adhesive composition with ultraviolet absorption function.

[0175] The UV-absorbing adhesive composition was applied to the release film after peeling, such that the adhesive layer had a thickness of 150 μm. The release film was then adhered to the surface of the adhesive composition layer. Then, at an illuminance of 6.5 mW / cm²... 2 Light intensity: 1500 mJ / cm 2 Under ultraviolet light irradiation conditions, the adhesive composition layer is photocured, thereby forming the visual recognition side adhesive layer (A-1).

[0176] (Fabrication of polarizing film (P-1))

[0177] A polarizing film (P-1) was fabricated by bonding a 25 μm thick triacetyl cellulose film to the visual recognition side of a polarizer containing a 12 μm thick stretched polyvinyl alcohol film impregnated with iodine, using a polyvinyl alcohol adhesive, and then laminating a 20 μm thick acrylic film onto the image display side surface of the polarizer using a polyvinyl alcohol adhesive. The polarization degree of the polarizing film is 99.995.

[0178] (Manufacturing of polarizing films with adhesive layers)

[0179] A visual recognition-side adhesive layer (A-1) is laminated on the visual recognition side of the polarizing film (P-1) (i.e., the surface of the 25 μm thick triacetyl cellulose membrane). An image display-side adhesive layer (B-1) is laminated on the image display-side surface of the polarizing film (P-1) (i.e., the surface of the 20 μm thick acrylic membrane), and a phase retardation film (thickness: 56 μm, material: polycarbonate) and an image display-side adhesive layer (B-2) are further laminated, thereby forming a polarizing film with an adhesive layer. The resulting polarizing film with an adhesive layer has the structure of visual recognition-side adhesive layer (A-1) / polarizing film (P-1) / image display-side adhesive layer (B-1) / phase retardation film / image display-side adhesive layer (B-2).

[0180] Examples 2-10

[0181] Except that the amount of ultraviolet absorber added and the thickness of the adhesive layer after the formation of the visual recognition side were changed to those described in Table 1, a polarizing film with an adhesive layer was formed in the same manner as in Example 1.

[0182] Examples 11-13

[0183] Except for the absence of a phase retardation film and an adhesive layer (B-2) on the image display side, a polarizing film with an adhesive layer was formed in the same manner as in Examples 1 to 3.

[0184] Comparative Examples 1-4

[0185] Except that the type of polarizing film used was changed to that described in Table 1 and no adhesive layer was formed on the visual recognition side, a polarizing film with an adhesive layer was formed in the same manner as in Examples 11 and 1. It should be noted that the polarizing film (P-2) is as follows.

[0186] (Fabrication of polarizing film (P-2))

[0187] A polarizing film (P-2) was fabricated by bonding a 60 μm thick triacetylcellulose film to the visual recognition side of a polarizer containing a 12 μm thick stretched polyvinyl alcohol film impregnated with iodine using a polyvinyl alcohol adhesive, and by laminating a 40 μm thick triacetylcellulose film onto the image display side surface of the polarizer using a polyvinyl alcohol adhesive. The polarization degree of the polarizing film is 99.995.

[0188] Comparative Examples 5-8

[0189] Except that the type of acrylic adhesive composition forming the visual recognition side adhesive layer and the amount of ultraviolet absorber added are changed as described in Table 1, a polarizing film with an adhesive layer is formed in the same manner as in Examples 11 and 1.

[0190] The obtained adhesive layer and the polarizing film with the adhesive layer were evaluated as follows.

[0191] <Polymerization Rate>

[0192] The release film of the visual recognition side adhesive layer used in the examples and comparative examples was peeled off, and only the visual recognition side adhesive layer was placed in an aluminum dish after weighing. The weight of (aluminum dish + visual recognition side adhesive layer) was measured to determine the weight of the adhesive layer before drying. After drying at 130°C for 2 hours, it was cooled at room temperature for about 20 minutes, and then the weight of (aluminum dish + adhesive) was measured again to determine the weight of the dried visual recognition side adhesive layer. The polymerization rate was calculated according to the following formula.

[0193]

[0194] <Gel fraction>

[0195] Approximately 0.1 g of the visual recognition side adhesive layer used in the examples and comparative examples was selected, coated with a porous tetrafluoroethylene sheet (trade name: NTF1122, manufactured by Nitto Denko Corporation) with an average pore size of 0.2 μm, and then tied with kite string. The weight at this point (Z g) was measured and taken as the weight before impregnation. It should be noted that the weight before impregnation is the total weight of the visual recognition side adhesive layer (the adhesive layer selected above), the tetrafluoroethylene sheet, and the kite string. In addition, the total weight of the tetrafluoroethylene sheet and the kite string (Y g) was also measured. Next, the visual recognition side adhesive layer (referred to as the "sample") coated with the tetrafluoroethylene sheet and tied with kite string was placed in a 50 mL container filled with ethyl acetate and left to stand at 23°C for 7 days. Then, the sample (after ethyl acetate treatment) was removed from the container, transferred to an aluminum cup, dried in a desiccator at 130°C for 2 hours to remove the ethyl acetate, and then the weight (X g) was measured and taken as the weight after impregnation. The gel fraction is calculated using the following formula.

[0196] Gel fraction (weight %) = (XY) / (ZY) × 100

[0197] <Determination of transmittance and b* value of the adhesive layer on the visual recognition side>

[0198] The release film of the visual recognition side adhesive layer used in the examples and comparative examples was peeled off, the visual recognition side adhesive layer was mounted on the measuring fixture, and the measurement was performed using a spectrophotometer (product name: U4100, manufactured by Hitachi High Technology Co., Ltd.).

[0199] <Residual Stress>

[0200] A test piece was prepared by cutting a 30mm wide and 50mm long sheet from the visual recognition side adhesive layer used in the examples and comparative examples and forming it into a cylindrical shape. With a clamp spacing of 20mm, the test piece was stretched by 60mm (300%) at a stretching speed of 200mm / min (the clamp spacing after stretching was 80mm). The piece was fixed (held) at the 60mm stretch position for 300 seconds, and the stress value (N) after 300 seconds was measured. The residual stress was calculated according to the following formula.

[0201] Residual stress after 300 seconds = Stress value after 300 seconds (N) / (4 × thickness of test piece / 10)

[0202] <Optical Reliability>

[0203] Glass (trade name: S200200, thickness: 1.3 mm, size: 45 mm × 50 mm, manufactured by Matsunami Glass Industry Co., Ltd.) was bonded to both sides of the polarizing film with adhesive layer obtained in the Examples and Comparative Examples, and then subjected to autoclave treatment for 15 minutes (pressure: 0.5 MPa, temperature: 50 °C). For Comparative Examples 1 to 4, the adhesive layer on the image display side of the polarizing film or retardation film was bonded to the above glass, and the same autoclave treatment was performed. Then, under various reliability conditions, the transmittance was measured using a UV-Vis-NIR spectrophotometer (product name: V7100, manufactured by Nippon Spectrophotometer Co., Ltd.). The change in transmittance compared to the initial value was calculated. Evaluation was performed according to the following evaluation criteria.

[0204] (Various reliability conditions)

[0205] (Condition 1) 85℃ × 500 hours

[0206] (Condition 2) 60℃, 95% × 500 hours

[0207] (Condition 3) Thermal shock (HS) (-40℃~85℃) × 300 cycles

[0208] (Condition 4) UV irradiation for 100 hours, illuminance: 500 W / cm² 2 (300nm~700nm), ambient temperature: 60℃~65℃, ambient humidity: 50%

[0209] (Evaluation Criteria)

[0210] ○: The change in transmittance is less than 2.0%.

[0211] △: Transmittance change is greater than 2.0% and less than 3.0%.

[0212] ×: Transmittance change is greater than 3.0%.

[0213] <Glue stains, dimensional accuracy, end appearance>

[0214] The polarizing films with adhesive layers obtained in the examples and comparative examples were cut into 25mm × 30mm pieces using a super-cutting machine. Then, the four sides of the cut pieces were cut by 0.05mm using an end-face processing machine (manufactured by Megaro Technica Co., Ltd.) to produce samples. The presence or absence of adhesive residue was confirmed by visually inspecting the sides of the samples. Dimensional accuracy and end appearance were observed using an optical microscope, and the following evaluation criteria were used.

[0215] (Dimensional accuracy)

[0216] ○: Within ±0.3mm

[0217] ×: Greater than ±0.3mm

[0218] (End appearance)

[0219] ○: The end is not sticky when touched by hand.

[0220] ×: The end is sticky when touched by hand.

[0221]

[0222] In Table 1,

[0223] P-1 represents the polarizing film (P-1).

[0224] P-2 represents the polarizing film (P-2).

[0225] a-1 represents the acrylic adhesive composition (a-1) obtained in Manufacturing Example 1.

[0226] a-2 represents the acrylic adhesive composition (a-2) obtained in Manufacturing Example 2.

[0227] B-1 indicates the image display side adhesive layer (B-1) obtained in Manufacturing Example 3.

[0228] B-2 indicates the adhesive layer (B-2) on the image display side obtained in manufacturing example 4.

[0229] Figure Labels

[0230] 1. Polarizing film with adhesive layer

[0231] 2a Visual recognition side adhesive layer

[0232] 2b Adhesive layer on the image display side

[0233] 3a Transparent protective film for visual recognition side

[0234] 3b Transparent protective film on the image display side

[0235] 4. Polarizer

[0236] 5. Polarizing film

[0237] 6. Protect the glass or plastic

[0238] 7. Liquid crystal display (LCD) or organic OLED display.

[0239] 8a, 8b Adhesive layers

[0240] 9. Sensor Layer

Claims

1. A polarizing film with an adhesive layer, said polarizing film with an adhesive layer being used in an image display device at a portion closer to the visual recognition side than the image display section. Its features are, The polarizing film with adhesive layer has a polarizing film and adhesive layers on both sides of the polarizing film. The polarizing film has a polarizer and transparent protective films on both sides of the polarizer. The transparent protective film on the visual recognition side of the polarizer has a transmittance of 6% or more and 17% or less at a wavelength of 380nm, and The adhesive layer on the visual recognition side of the polarization film has ultraviolet absorption capabilities. The thickness of the adhesive layer on the visual recognition side of the polarizing film is more than 50 μm and less than 250 μm. The thickness of the transparent protective film on the visual recognition side of the polarizer is greater than 1 μm and less than 40 μm. The transparent protective film on the visual recognition side of the polarizer is a triacetyl cellulose film. The polymer forming the transparent protective film on the image display side of the polarizer is at least one selected from the group consisting of acrylic polymers, styrene polymers, polycarbonate polymers, polyolefin polymers, vinyl chloride polymers, amide polymers, imide polymers, sulfone polymers, polyethersulfone polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aromatic ester polymers, polyoxymethylene polymers, and epoxy polymers. The adhesive layer on the visual recognition side of the polarizing film contains a (meth)acrylic polymer and an ultraviolet absorber. The content of the ultraviolet absorber is 0.1 to 5 parts by weight relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer. The adhesive layer on the visual recognition side is formed by ultraviolet polymerization of a UV-curable acrylic adhesive composition, which comprises: a monomeric component containing an alkyl methacrylate and / or a portion of the polymer of the monomeric component, an ultraviolet absorber, and a photopolymerization initiator (A) having an absorption band at a wavelength above 400 nm. The transmittance of the adhesive layer on the visual recognition side of the polarizing film at a wavelength of 380 nm is less than 40%, and the transmittance of the adhesive layer on the visual recognition side of the polarizing film at a wavelength of 400 nm is more than 30%. The b* value of the adhesive layer on the visual recognition side of the polarizing film is less than 3.

0.

2. The polarizing film with an adhesive layer as described in claim 1, characterized in that, The thickness of the adhesive layer on the visual recognition side of the polarizing film is more than twice the thickness of the adhesive layer on the image display side of the polarizing film.

3. The polarizing film with an adhesive layer as described in claim 1, characterized in that, The polarizing film with adhesive layer is used in liquid crystal display devices or organic EL display devices.

4. An image display device, characterized in that, A polarizing film with an adhesive layer, as described in any one of claims 1 to 3, is used in a portion closer to the visual recognition side than the image display portion.

Images