JP2024086737A - Polarizing film with pressure-sensitive adhesive layer and image display device - Google Patents

Abstract

[Problem] The present invention aims to provide a polarizing film with an adhesive layer that can solve the problem of reduced yield and can provide sufficient ultraviolet ray blocking function even when the polarizing film is thin. Another object of the present invention is to provide an image display device using the polarizing film with an adhesive layer. [Solution] A polarizing film with an adhesive layer that is used on the viewing side of the image display unit in an image display device, the polarizing film with an adhesive layer having a polarizing film and an adhesive layer on both sides of the polarizing film, the polarizing film having a polarizer and a transparent protective film on both sides of the polarizer, the transparent protective film on the viewing side of the polarizer has a transmittance at a wavelength of 380 nm of 6% or more, and the adhesive layer on the viewing side of the polarizing film has an ultraviolet ray absorbing function. [Selected Figure] Figure 1

Description

The present invention relates to a polarizing film with an adhesive layer for use in an image display device. The present invention also relates to an image display device using the polarizing film with an adhesive layer. Examples of image display devices include liquid crystal display devices, organic EL (electroluminescence) display devices, PDPs (plasma display panels), electronic paper, etc.

Due to the image formation method used by liquid crystal display devices and organic EL display devices, for example, it is essential to place polarizing elements on both sides of the liquid crystal cell in liquid crystal display devices, and polarizing films are generally attached to the cells. In addition to polarizing films, various optical elements are now being used in display panels such as liquid crystal panels and organic EL panels to improve the display quality.

The polarizing films used in these image display devices generally have a structure in which a polarizer is sandwiched between two protective films, and triacetyl cellulose (TAC) is commonly used as the protective film.

In recent years, with the trend towards lighter and thinner image display devices, thinner components are being required for image display devices, including the protective film of the polarizing film. When the protective film becomes too thin, it is no longer possible to adequately block ultraviolet light entering the image display device, and this causes problems such as accelerated deterioration due to ultraviolet light not only of polarizers but also of various optical components such as liquid crystal panels and organic EL elements used in image display devices.

To solve such problems, for example, a double-sided pressure-sensitive adhesive sheet for an image display device is known, which is disposed between a surface protection panel and a viewing side of a liquid crystal module in the image display device to integrate the two components, and which has at least one ultraviolet absorbing layer and has a light transmittance of 30% or less at a wavelength of 380 nm and a visible light transmittance of 80% or more at wavelengths longer than 430 nm (see, for example, Patent Document 1), and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing an acrylic polymer and a triazine-based ultraviolet absorber (see, for example, Patent Document 2). It is also known that in a pressure-sensitive adhesive optical film in which a pressure-sensitive adhesive layer is provided on one or both sides of the optical film, the pressure-sensitive adhesive layer can be given ultraviolet absorbing ability (see, for example, Patent Document 3).

JP 2012-211305 A JP 2013-75978 A Japanese Patent No. 4208187

In recent years, as described in Patent Documents 1 to 3, it has become known to use a transparent adhesive with ultraviolet absorbing properties to bond various components used in image display devices, but this method has presented problems such as uneven thickness, poor yield, and workability.

The present invention aims to provide a polarizing film with an adhesive layer that can solve the problem of reduced yield and can provide sufficient UV protection even when the polarizing film is thin. Another aim of the present invention is to provide an image display device that uses the polarizing film with an adhesive layer.

As a result of extensive research into solving the above problems, the inventors discovered the following polarizing film with a pressure-sensitive adhesive layer, and completed the present invention.

That is, the present invention provides a polarizing film with a pressure-sensitive adhesive layer, which is used on the viewing side of an image display unit in an image display device,
The pressure-sensitive adhesive layer-attached polarizing film has a polarizing film and pressure-sensitive 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 polarizing film with a pressure-sensitive adhesive layer is characterized in that the transparent protective film on the viewing side of the polarizer has a transmittance of 6% or more at a wavelength of 380 nm, and the pressure-sensitive adhesive layer on the viewing side of the polarizing film has an ultraviolet absorbing function.

It is preferable that the transparent protective film on the viewing 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 cyclo- or norbornene structure, and has a thickness of 40 μm or less.

It is preferable that the thickness of the adhesive layer on the viewing side of the polarizing film is at least twice the thickness of the adhesive layer on the image display side of the polarizing film.

It is preferable that the adhesive layer on the viewing side of the polarizing film has a transmittance of 40% or less at a wavelength of 380 nm and a transmittance of 30% or more at a wavelength of 400 nm.

It is preferable that the b* value of the adhesive layer on the viewing side of the polarizing film is 3.0 or less.

It is preferable that the adhesive layer on the viewing side of the polarizing film contains an acrylic polymer as the base polymer.

The polarizing film with the adhesive layer of the present invention is preferably used in a liquid crystal display device or an organic EL display device.

The present invention also relates to an image display device that uses the above-mentioned polarizing film with an adhesive layer on the viewing side of the image display section.

The polarizing film with adhesive layer of the present invention is configured such that an adhesive layer having an ultraviolet absorbing function is pre-laminated on the viewing side of the polarizing film, and therefore it is possible to solve the problems of process elimination and reduced yield, and even if the polarizing film is thin, it is possible to impart sufficient ultraviolet blocking function. In addition, since the image display device of the present invention uses the polarizing film with adhesive layer, it is possible to suppress ultraviolet degradation of various optical components, including liquid crystal panels and organic EL elements, used in the image display device.

1 is a cross-sectional view that illustrates a schematic diagram of one embodiment of a pressure-sensitive adhesive layer-attached polarizing film of the present invention. 1 is a cross-sectional view that illustrates a schematic diagram of an embodiment of an image display device of the present invention. 1 is a cross-sectional view that illustrates a schematic diagram of an embodiment of an image display device of the present invention. 1 is a cross-sectional view that illustrates a schematic diagram of an embodiment of an image display device of the present invention.

1. Polarizing film with pressure-sensitive adhesive layer The polarizing film with pressure-sensitive adhesive layer of the present invention is used on the viewing side of the image display unit in an image display device,
The pressure-sensitive adhesive layer-attached polarizing film has a polarizing film and pressure-sensitive 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 viewing side of the polarizer has a transmittance of 6% or more at a wavelength of 380 nm, and the pressure-sensitive adhesive layer on the viewing side of the polarizing film has an ultraviolet absorbing function.

As shown in FIG. 1, the polarizing film 1 with the adhesive layer of the present invention may be configured to include a visible-side adhesive layer 2a/a visible-side transparent protective film 3a/a polarizer 4/a transparent protective film 3b on the image display unit side/a adhesive layer 2b on the image display unit side, and may further include a retardation film or the like. Specifically, the polarizing film 5 may be configured to include a visible-side adhesive layer 2a/a visible-side transparent protective film 3a/a polarizer 4/a transparent protective film 3b on the image display unit side/a adhesive layer 2b on the image display unit side/a retardation film (not shown)/a adhesive layer on the image display unit side (not shown). The polarizing film 5 is configured to include a visible-side transparent protective film 3a/a polarizer 4/a transparent protective film 3b on the image display unit side. Each layer will be described in detail below.

(1) Visible-side pressure-sensitive adhesive layer In the present invention, the visible-side pressure-sensitive adhesive layer of the polarizing film (visible-side pressure-sensitive adhesive layer) has an ultraviolet absorbing function. The visible-side pressure-sensitive adhesive layer may have an ultraviolet absorbing function, and the composition thereof is not particularly limited.

Any suitable adhesive can be used to form the visible side adhesive layer, and there is no particular restriction on the type. Examples of adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these adhesives, acrylic-based adhesives are preferably used because they have excellent optical transparency, exhibit suitable adhesive properties such as adhesion, cohesion, and bonding, and are excellent in weather resistance and heat resistance. The acrylic adhesive contains an acrylic polymer as a base polymer.

The visible-side adhesive layer using the acrylic adhesive is preferably formed by, for example, ultraviolet polymerization of an ultraviolet-curable acrylic adhesive composition containing a monomer component containing alkyl (meth)acrylate and/or 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 more. The adhesive layer formed by ultraviolet polymerization of the ultraviolet-curable acrylic adhesive composition can be formed to a thickness of 150 μm or more, and is preferable because an adhesive layer of a wide range of thicknesses can be formed.

The alkyl (meth)acrylate may be, for example, one having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester end. The alkyl (meth)acrylate may be used alone or in combination of two or more. Note that alkyl (meth)acrylate refers to alkyl acrylate and/or alkyl methacrylate, and (meth) in the present invention has the same meaning.

As the alkyl (meth)acrylate, for example, an alkyl (meth)acrylate having a branch having 4 to 9 carbon atoms can be exemplified. The alkyl (meth)acrylate is preferable in that it is easy to balance the adhesive properties. Specific examples include n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, etc., and these can be used alone or in combination of two or more.

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

The monomer component may contain a copolymerizable monomer other than the alkyl (meth)acrylate as a monofunctional monomer component. The copolymerizable monomer may be used as the remainder of the alkyl (meth)acrylate in the monomer component.

The copolymerization monomer may include, for example, a cyclic nitrogen-containing monomer. As the cyclic nitrogen-containing monomer, a monomer having a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and having a cyclic nitrogen structure may be used without particular limitation. The cyclic nitrogen structure is preferably one having a nitrogen atom in the cyclic structure. Examples of the cyclic nitrogen-containing monomer include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinyl-based monomers having nitrogen-containing heterocycles such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine. In addition, (meth)acrylic monomers containing heterocycles such as morpholine ring, piperidine ring, pyrrolidine ring, and piperazine ring may be used. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine. Among the cyclic nitrogen-containing monomers, lactam vinyl monomers are preferred.

In the present invention, the amount of 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, based on the total amount of the monofunctional monomer components forming the (meth)acrylic polymer.

The monomer component used in the present invention may contain a hydroxyl group-containing monomer as a monofunctional monomer component. As the hydroxyl group-containing monomer, a monomer having a polymerizable functional group with an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and having a hydroxyl group may be used without any particular limitation. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and hydroxyalkyl cycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Other examples include hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, etc. These can be used alone or in combination. Among these, hydroxyalkyl (meth)acrylates are preferred.

In the present invention, the hydroxyl group-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, based on the total amount of the monofunctional monomer components forming the (meth)acrylic polymer, in order to increase the adhesive strength and cohesive strength. On the other hand, if the amount of the hydroxyl group-containing monomer is too large, the adhesive layer may become hard and the adhesive strength may decrease, and the adhesive may become too viscous or gel. Therefore, the hydroxyl group-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, based on the total amount of the monofunctional monomer components forming the (meth)acrylic polymer.

In addition, the monomer components forming the (meth)acrylic polymer may contain other functional group-containing monomers as monofunctional monomers, such as carboxyl group-containing monomers and monomers having cyclic ether groups.

As the carboxyl group-containing monomer, any monomer having a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and having a carboxyl group can be used without any particular restrictions. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc., which can be used alone or in combination. Anhydrides of itaconic acid and maleic acid can be used. Among these, acrylic acid and methacrylic acid are preferred, and acrylic acid is particularly preferred. In addition, a carboxyl group-containing monomer can be used as the monomer component used in the production of the (meth)acrylic polymer of the present invention, and on the other hand, a carboxyl group-containing monomer may not be used.

As the monomer having a cyclic ether group, those having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group, and having a cyclic ether group such as an epoxy group or an oxetane group, can be used without any particular restrictions. Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc. Examples of oxetane group-containing monomers include 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, 3-hexyl-oxetanylmethyl (meth)acrylate, etc. These can be used alone or in combination.

In the present invention, the amount of the carboxyl group-containing monomer and the monomer having a cyclic ether group is preferably 30% by weight or less, more preferably 27% by weight or less, and even more preferably 25% by weight or less, based on the total amount of the monofunctional monomer components forming the (meth)acrylic polymer.

The monomer components forming the (meth)acrylic polymer of the present invention include, as copolymerizable monomers, alkyl (meth)acrylates represented by CH ₂ ═C(R ¹ )COOR ² (wherein R ¹ represents hydrogen or a methyl group, and R ² represents a substituted alkyl group having 1 to 3 carbon atoms, or a cyclic cycloalkyl group).

Here, the substituent of the substituted alkyl group having 1 to 3 carbon atoms as ^R2 is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. The aryl group is not limited, but a phenyl group is preferable.

Examples of such monomers represented by CH ₂ ═C(R ¹ )COOR ² include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. These can be used alone or in combination.

In the present invention, the (meth)acrylate represented by _CH2 =C( ^R1 ) ^COOR2 can be used in an amount of 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, based on the total amount of the monofunctional monomer components forming the (meth)acrylic polymer.

Other copolymerizable monomers include vinyl acetate, vinyl propionate, styrene, α-methylstyrene; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, and vinyl ether monomers. In addition, monomers having a cyclic structure such as terpene (meth)acrylate and dicyclopentanyl (meth)acrylate can be used as copolymerizable monomers.

Further examples include silane-based monomers containing silicon atoms. Examples of silane-based monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

In addition to the monofunctional monomers exemplified above, the monomer components forming the (meth)acrylic polymer of the present invention may contain polyfunctional monomers as necessary to adjust the cohesive strength of the adhesive.

A polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and examples thereof include (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, and 1,2-ethylene glycol di(meth)acrylate. Examples of suitable polyfunctional monomers include ester compounds of polyhydric alcohols and (meth)acrylic acid, such as 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate. Among these, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate can be preferably used. The polyfunctional monomers can be used alone or in combination of two or more.

The amount of polyfunctional monomer used varies depending on its molecular weight, number of functional groups, etc., but is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and even more preferably 1 part by weight or less, per 100 parts by weight of monofunctional monomers in total. The lower limit is not particularly limited, but is preferably 0 parts by weight or more, and more preferably 0.001 parts by weight or more. By using the polyfunctional monomer in an amount within the above range, the adhesive strength can be improved.

In the present invention, the monomer component may be partially polymerized.

The ultraviolet absorbing agent contained in the ultraviolet curing acrylic adhesive composition is not particularly limited, but examples thereof include triazine-based ultraviolet absorbing agents, benzotriazole-based ultraviolet absorbing agents, benzophenone-based ultraviolet absorbing agents, oxybenzophenone-based ultraviolet absorbing agents, salicylic acid ester-based ultraviolet absorbing agents, and cyanoacrylate-based ultraviolet absorbing agents, and these can be used alone or in combination of two or more. Among these, triazine-based ultraviolet absorbing agents and benzotriazole-based ultraviolet absorbing agents are preferred, and at least one ultraviolet absorbing agent selected from the group consisting of triazine-based ultraviolet absorbing agents having two or less hydroxyl groups in one molecule and benzotriazole-based ultraviolet absorbing agents having one benzotriazole skeleton in one molecule is preferred because it has good solubility in the monomer used to form the ultraviolet curing acrylic adhesive composition and has high ultraviolet absorbing ability at a wavelength of around 380 nm.

Specific examples of triazine-based UV absorbers having two or less hydroxyl groups per molecule 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), reaction products of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (TINUVIN 400, manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyf Reaction product of 2-(4,6-diphenyl-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (TINUVIN 405, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol (TINUVIN 1577, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (ADK Examples include STAB LA46, manufactured by ADEKA, and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN479, manufactured by BASF).

In addition, examples of benzotriazole-based UV absorbers having one benzotriazole skeleton per 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 compound of benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and linear alkyl) (TINUVIN384-2, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN900, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN900, manufactured by BASF), methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 reaction product (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 (TINUVIN 234, manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (TINUVIN 326, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN 328, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN N329, manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (TINUVIN 213, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN 571, manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Co., Ltd.), etc.

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

Examples of the salicylic acid ester-based ultraviolet absorber (salicylic acid ester-based compound) 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, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (TINUVIN120, manufactured by BASF), and the like.

Examples of the cyanoacrylate-based ultraviolet absorber (cyanoacrylate-based compound) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

The ultraviolet absorbers may be used alone or in combination of two or more kinds, but the total content is preferably about 0.1 to 5 parts by weight, and more preferably about 0.5 to 3 parts by weight, per 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer. By setting the amount of ultraviolet absorber added within the above range, the ultraviolet absorbing function of the adhesive layer can be fully exerted and ultraviolet polymerization is not hindered, which is preferable.

The ultraviolet-curable acrylic adhesive composition used in the present invention preferably contains a photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more. When an ultraviolet absorber is contained in the adhesive composition, ultraviolet light is absorbed by the ultraviolet absorber when ultraviolet polymerization is performed, and polymerization cannot be carried out sufficiently. However, the ultraviolet-curable acrylic adhesive composition used in the present invention contains a photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more, and therefore can be polymerized sufficiently despite the inclusion of an ultraviolet absorber.

Examples of photopolymerization initiators (A) that have an absorption band at wavelengths of 400 nm or more include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819, manufactured by BASF) and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (LUCIRIN TPO, manufactured by BASF).

The photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more may be used alone or in combination of two or more.

The amount of the photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more added is not particularly limited, but is preferably less than the amount of the ultraviolet absorber added, and is preferably about 0.005 to 1 part by weight, and more preferably about 0.02 to 0.5 parts by weight, per 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer. It is preferable that the amount of the photopolymerization initiator (A) added is within the above range, since ultraviolet polymerization can proceed sufficiently.

The ultraviolet-curable acrylic adhesive composition used in the present invention may contain a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm. The photopolymerization initiator (B) preferably does not have an absorption band at a wavelength of 400 nm or more. The photopolymerization initiator (B) is not particularly limited as long as it generates radicals by ultraviolet light and initiates photopolymerization and has an absorption band at a wavelength of less than 400 nm, and any photopolymerization initiator that is commonly used can be suitably used. For example, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, etc. can be used.

Specific examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, and anisole methyl ether.

Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-t-butyldichloroacetophenone.

Examples of α-ketol photopolymerization initiators include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-hydroxy-2-methylpropan-1-one, etc.

Examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime.

Benzoin-based photopolymerization initiators include, for example, benzoin.

Benzyl-based photopolymerization initiators include, for example, benzyl.

Benzophenone-based photopolymerization initiators include, for example, benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, etc.

Ketal-based photopolymerization initiators include benzyl dimethyl ketal, etc.

Thioxanthone-based photopolymerization initiators include, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, etc.

Examples of acylphosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc.

The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm may be used alone or in combination of two or more kinds. The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm may be added in an amount that does not impair the effects of the present invention, and the amount added is preferably about 0.005 to 0.5 parts by weight, and more preferably about 0.02 to 0.1 parts by weight, per 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer.

In the present invention, it is preferable to first add a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm to the monomer component, and then add a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more and an ultraviolet absorber to a partial polymer (prepolymer composition) of the monomer component partially polymerized by irradiating ultraviolet light, and then polymerize with ultraviolet light. When adding the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more to a partial polymer (prepolymer composition) of the monomer component partially polymerized by irradiating ultraviolet light, it is preferable to add the photopolymerization initiator after dissolving it in the monomer.

Furthermore, the ultraviolet-curable acrylic adhesive composition used in the present 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 to 1 part by weight, and even more preferably 0.02 to 0.6 parts by weight, per 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer.

Examples of the silane coupling agent include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane.

The ultraviolet-curable acrylic adhesive composition used in the present invention may contain a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, and peroxide-based crosslinking agents. The crosslinking agents may be used alone or in combination of two or more. Among these, isocyanate-based crosslinking agents are preferably used.

The above crosslinking agents may be used alone or in combination of two or more, but the total content is preferably 5 parts by weight or less, more preferably 0.01 to 5 parts by weight, even more preferably 0.01 to 4 parts by weight, and particularly preferably 0.02 to 3 parts by weight, relative to 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer.

An isocyanate-based crosslinking agent is a compound that has two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate group is temporarily protected by a blocking agent or oligomerization) in one molecule. Examples of isocyanate-based crosslinking agents include aromatic isocyanates such as tolylene diisocyanate and xylylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

More specifically, for example, 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-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate, trimethylolpropane/tolylene diisocyanate trimer adduct (product name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane/hexamethylene diisocyanate trimer adduct (product name: Examples of such polyisocyanates include isocyanate adducts such as Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), isocyanurate of hexamethylene diisocyanate (product name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane adduct of xylylene diisocyanate (product name: D110N, manufactured by Mitsui Chemicals, Inc.), trimethylolpropane adduct of hexamethylene diisocyanate (product name: D160N, manufactured by Mitsui Chemicals, Inc.); polyether polyisocyanates, polyester polyisocyanates, and adducts of these with various polyols, polyisocyanates multifunctionalized with isocyanurate bonds, biuret bonds, allophanate bonds, etc.

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

In the present invention, the ultraviolet-curable acrylic adhesive composition is preferably adjusted to a viscosity suitable for application to a substrate. The viscosity of the ultraviolet-curable acrylic adhesive composition is adjusted, for example, by adding various polymers such as thickening additives or polyfunctional monomers, or by partially polymerizing the monomer components in the ultraviolet-curable acrylic adhesive composition. The partial polymerization may be performed before or after adding various polymers such as thickening additives or polyfunctional monomers. Since the viscosity of the ultraviolet-curable acrylic adhesive composition varies depending on the amount of additives, the polymerization rate when the monomer components in the ultraviolet-curable acrylic adhesive composition are partially polymerized cannot be uniquely determined, but as a guideline, it is preferably about 20% or less, more preferably about 3 to 20%, and even more preferably about 5 to 15%. If it exceeds 20%, the viscosity becomes too high, making it difficult to apply to a substrate.

The visible-side adhesive layer can be formed by applying the ultraviolet-curable acrylic adhesive composition to at least one side of a substrate and irradiating the ultraviolet-curable acrylic adhesive composition with ultraviolet light.

The substrate is not particularly limited, and for example, various substrates such as release films and transparent resin film substrates, as well as the polarizing film described below, can be suitably used as the substrate. When the visible-side adhesive layer is formed on a substrate other than a polarizing film, the visible-side adhesive layer can be transferred by bonding it to the polarizing film.

Examples of materials that can be used for the release film include resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabrics; nets, foam sheets, metal foils, and laminates of these materials; and other suitable thin materials. Resin films are preferably used because of their excellent surface smoothness.

Examples of such resin films include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, and ethylene-vinyl acetate copolymer films.

The thickness of the release film is usually 5 to 200 μm, and preferably about 5 to 100 μm. If necessary, the release film can be subjected to a release and antifouling treatment using a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, silica powder, etc., or an antistatic treatment such as a coating type, kneading type, or deposition type. In particular, by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film, the releasability from the pressure-sensitive adhesive layer can be further improved.

As the transparent resin film substrate, although there is no particular limitation, various resin films having transparency can be used. The resin film is formed of a single layer of film. For example, the material can be polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, polyphenylene sulfide-based resins, etc. Among these, polyester-based resins, polyimide-based resins, and polyethersulfone-based resins are particularly preferred.

The thickness of the film substrate is preferably 15 to 200 μm, and more preferably 25 to 188 μm.

The method for applying the ultraviolet-curable acrylic adhesive composition to the substrate is not particularly limited, and any suitable known method may be used, such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, or die coating.

The illuminance of the ultraviolet light irradiated to the ultraviolet-curable acrylic pressure-sensitive adhesive composition is preferably 5 mW/cm ² or more. If the illuminance of the ultraviolet light is less than 5 mW/cm ² , the polymerization reaction time may be long, resulting in poor productivity. The illuminance of the ultraviolet light is preferably 200 mW/cm ² or less. If the illuminance of the ultraviolet light exceeds 200 mW/cm ² , the photopolymerization initiator is rapidly consumed, resulting in low molecular weight of the polymer, and the retention force may decrease, especially at high temperatures. The integrated light amount of the ultraviolet light is preferably 100 mJ/cm ² to 5000 mJ/cm ² .

The ultraviolet lamp used in the present invention is not particularly limited, but an LED lamp is preferable. LED lamps emit less heat than other ultraviolet lamps, so the temperature during polymerization of the adhesive layer can be suppressed. This prevents the polymer from becoming low molecular weight, prevents a decrease in the cohesive strength of the adhesive layer, and increases the holding power at high temperatures when made into an adhesive sheet. It is also possible to combine multiple ultraviolet lamps. It is also possible to irradiate ultraviolet light intermittently, providing a light period during which ultraviolet light is irradiated and a dark period during which ultraviolet light is not irradiated.

In the present invention, the final polymerization rate of the monomer components in the ultraviolet-curable acrylic adhesive composition is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

In the present invention, the peak wavelength of the ultraviolet light irradiated to the ultraviolet-curable acrylic adhesive composition is preferably in the range of 200 to 500 nm, and more preferably in the range of 300 to 450 nm. If the peak wavelength of the ultraviolet light exceeds 500 nm, the photopolymerization initiator may not decompose and the polymerization reaction may not start. If the peak wavelength of the ultraviolet light is less than 200 nm, the polymer chain may be broken, resulting in a decrease in adhesive properties.

The reaction is inhibited by oxygen in the air, so to block oxygen, it is preferable to form a release film or the like on the coating layer of the acrylic adhesive composition, or to carry out the photopolymerization reaction in a nitrogen atmosphere. Examples of the release film include those mentioned above. When a release film is used, the release film can be used as it is as a separator for the polarizing film with the adhesive layer.

From the viewpoint of ensuring ultraviolet absorbing function, the thickness of the visible-side adhesive layer is preferably at least twice, more preferably at least five times, and even more preferably at least ten times, the thickness of the adhesive layer on the image display section side of the polarizing film described later (image display section side adhesive layer). Specifically, the thickness of the visible-side adhesive layer is preferably at least 50 μm, more preferably at least 100 μm, and even more preferably at least 150 μm. The upper limit of the thickness of the visible-side adhesive layer is not particularly limited, but is preferably 10 mm or less. If the thickness of the adhesive layer exceeds 10 mm, ultraviolet light transmission becomes difficult, polymerization of the monomer component takes time, and productivity may be poor, which is not preferable.

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

As described above, when forming an adhesive layer from an ultraviolet-curable acrylic adhesive composition containing a photopolymerization initiator (B), the polymerization rate of the monomer components can be increased by carrying out the two-stage polymerization as described above, and the ultraviolet absorbing function of the finally produced adhesive layer can be improved.

The gel fraction of the visible-side adhesive layer of the present invention is not particularly limited, but is preferably 50% or more, more preferably 75% or more, and even more preferably 85% or more. If the gel fraction of the visible-side adhesive layer is small, the cohesive strength may be poor, and if it is too large, the adhesive strength may be poor.

The transmittance b* value of the visible-side adhesive layer is not particularly limited, but is preferably 3.0 or less, more preferably 1.5 or less, and even more preferably 0.5 or less. The b* value refers to the b* value (chromaticity) in the L*a*b* color system according to JIS Z8729, and can be measured, for example, using a spectrophotometer (product name: U4100, manufactured by Hitachi High-Technologies Corporation).

The transmittance of the visible side adhesive layer at a wavelength of 380 nm is preferably 40% or less, more preferably 20% or less, and even more preferably 8% or less. By having a transmittance wavelength at a wavelength of 380 nm within the above range, incident ultraviolet light can be sufficiently blocked, thereby suppressing deterioration of optical components such as liquid crystal panels, organic EL elements, polarizers, etc.

The transmittance of the visible side adhesive layer at a wavelength of 400 nm is preferably 30% or more, more preferably 50% or more, and more preferably 70% or more. By having a transmittance wavelength at a wavelength of 400 nm within the above range, it is possible to sufficiently transmit incident visible light, and it is preferable because sufficient visibility can be ensured in an image display device.

(2) Image Display Section Side Adhesive Layer The adhesive layer on the image display section side surface of the polarizing film (image display section side adhesive layer) is not particularly limited, and may be the same as the ultraviolet-curable acrylic adhesive composition described in detail for the viewing-side adhesive layer, or any of various commonly used adhesive layers.

To form the adhesive layer on the image display surface, any suitable adhesive can be used, with no particular restrictions on the type. Examples of adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these adhesives, acrylic-based adhesives are preferably used, since they have excellent optical transparency, exhibit suitable adhesive properties such as adhesion, cohesion, and bonding, and are excellent in weather resistance and heat resistance.

The acrylic adhesive has an acrylic polymer having a monomer unit of (meth)acrylic acid alkyl ester as the main skeleton as the base polymer. The (meth)acrylic acid alkyl ester constituting the main skeleton of the acrylic polymer can be the same as that used in the ultraviolet-curable acrylic adhesive composition that forms the visible-side adhesive layer. The copolymerization monomer and its ratio can also be the same as that used in the ultraviolet-curable acrylic adhesive composition.

The acrylic polymer can be produced by various known methods, for example, radical polymerization methods such as bulk polymerization, solution polymerization, and suspension polymerization. As the radical polymerization initiator, various known azo and peroxide initiators can be used. The reaction temperature is usually about 50 to 80°C, and the reaction time is 1 to 8 hours. Among the above production methods, the solution polymerization method is preferable, and ethyl acetate, toluene, etc. are generally used as the solvent for the acrylic polymer. The solution concentration is usually about 20 to 80% by weight.

The adhesive can also be an adhesive composition containing a crosslinking agent. Examples of crosslinking agents include those mentioned above, but isocyanate-based crosslinking agents are particularly preferred. The blend ratio of the acrylic polymer and crosslinking agent is not particularly limited, but typically, it is preferable that the crosslinking agent (solid content) is about 0.001 to 20 parts by weight, and more preferably about 0.01 to 15 parts by weight, per 100 parts by weight of the acrylic polymer (solid content).

Furthermore, the adhesive may contain, as necessary, tackifiers, plasticizers, fillers made of glass fibers, glass beads, metal powders, other inorganic powders, pigments, colorants, fillers, antioxidants, UV absorbers, silane coupling agents, etc., and various other additives may also be used as appropriate within the scope of the object of the present invention. It may also be an adhesive layer that contains fine particles and exhibits light diffusibility. Examples of silane coupling agents include those mentioned above.

The image display unit side adhesive layer is formed by applying the adhesive to various substrates such as a polarizing film or a release film, and drying the adhesive. When the adhesive layer is formed on various substrates such as a release film, the adhesive layer can be transferred by bonding to the polarizing film. The adhesive application method and the various substrates can be the same as the application method and the various substrates of the ultraviolet-curable acrylic adhesive composition.

In the coating process, the amount of coating is controlled so that the adhesive layer formed has a predetermined thickness (thickness after drying). The thickness of the image display unit side adhesive layer is not particularly limited, but is preferably 1/2 or less, more preferably 1/5 or less, and more preferably 1/10 or less of the thickness of the viewing side adhesive layer. Specifically, the thickness of the image display unit side adhesive layer is preferably about 1 to 100 μm, more preferably about 3 to 50 μm, and even more preferably about 5 to 30 μm.

When forming the image display unit side adhesive layer, the applied adhesive is dried. The drying temperature and drying time are not particularly limited and may be set appropriately, but for example, a temperature of about 80 to 200°C and a drying time of 0.5 to 10 minutes are preferable.

When the adhesive layer on the image display section side is exposed, the adhesive layer may be protected with a release film until it is put to practical use. The release film can be used as it is as a separator for the adhesive layer-attached polarizing film, which can simplify the process.

(3) Polarizing Film The polarizing film used in the present invention is characterized in that it has a polarizer and transparent protective films on both sides of the polarizer, and the transparent protective film on the viewing side of the polarizer (viewing-side transparent protective film) has a transmittance of 6% or more at a wavelength of 380 nm.

(3-1) Viewer-side transparent protective film The viewer-side transparent protective film used in the present invention has a transmittance at a wavelength of 380 nm of 6% or more, preferably 10% or more, and more preferably 15% or more. The upper limit of the transmittance at a wavelength of 380 nm is not particularly limited, but is preferably 90% or less, and more preferably 30% or less. The viewer-side transparent protective film has a transmittance at a wavelength of 380 nm in the above range, which is preferable because it is possible to achieve a sufficient ultraviolet absorption ability by combining the viewer-side transparent protective film with a thinner film and the viewer-side pressure-sensitive adhesive layer (containing an ultraviolet absorber). Even if the viewer-side transparent protective film does not have an ultraviolet absorption ability, the ultraviolet absorption function can be fully compensated for by the ultraviolet absorption by the viewer-side pressure-sensitive adhesive layer, so long as the transmittance at a wavelength of 380 nm is 90% or less, the viewer-side transparent protective film has a sufficient ultraviolet absorption ability. When the viewer-side pressure-sensitive adhesive layer has a transmittance of 40% or less at a wavelength of 380 nm, the viewer-side transparent protective film preferably has a transmittance of 30% or less at a wavelength of 380 nm from the viewpoint of ultraviolet absorbing ability.

As the material for forming the visible-side transparent protective film, those excellent in transparency, mechanical strength, thermal stability, moisture blocking properties, isotropy, etc. are preferable. For example, polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers (AS resin), polycarbonate-based polymers, etc. are listed. In addition, examples of polymers for forming the transparent protective film include polyethylene, polypropylene, polyolefins having a cyclo- or norbornene structure, polyolefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamide, imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and blends of the above polymers are also listed. The transparent protective film can also be formed as a cured layer of a thermosetting or ultraviolet curing resin such as an acrylic, urethane, acrylic urethane, epoxy, or silicone resin. Among these, the viewing side transparent protective film is preferably at least one film selected from the group consisting of a triacetyl cellulose film, an acrylic film (a film using an acrylic polymer), a polyethylene terephthalate film, and a polyolefin film having a cyclo- or norbornene structure, and more preferably a triacetyl cellulose film.

The thickness of the visible-side transparent protective film is not particularly limited, but is preferably 40 μm or less, more preferably 35 μm or less, and even more preferably 30 μm or less. The lower limit of the thickness of the visible-side transparent protective film is not particularly limited, but is preferably 1 μm or more. By having the thickness of the visible-side transparent protective film in the above range, it is possible to sufficiently achieve a thin polarizing film without impairing the protective function of the polarizer, which is preferable.

The polarizer and the viewing-side protective film described below are preferably adhered to each other via a water-based adhesive or the like. Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, water-based polyurethanes, water-based polyesters, and the like. In addition to the above, examples of adhesives between the polarizer and the viewing-side transparent protective film include ultraviolet-curing adhesives and electron beam-curing adhesives. Electron beam-curing polarizing film adhesives exhibit suitable adhesion to the various viewing-side transparent protective films described above. The adhesive used in the present invention may also contain a metal compound filler.

The surface of the viewing-side transparent protective film to which the polarizer is not attached may be provided with a hard coat layer, anti-reflection treatment, anti-sticking treatment, or treatment for diffusion or anti-glare purposes.

(3-2) Polarizer The polarizer is not particularly limited, and various polarizers can be used. Examples of polarizers include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which are uniaxially stretched after adsorbing a dichroic substance such as iodine or a dichroic dye, and polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. Among these, polarizers made of a polyvinyl alcohol film and a dichroic substance such as iodine are suitable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and stretching it uniaxially can be produced, for example, by immersing the polyvinyl alcohol in an aqueous solution of iodine to dye it and stretching it to 3 to 7 times its original length. If necessary, it can also be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride, or the like. Furthermore, if necessary, the polyvinyl alcohol-based film can be immersed in water and washed before dyeing. Washing the polyvinyl alcohol-based film with water can wash off dirt and blocking inhibitors on the surface of the polyvinyl alcohol-based film, and also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol-based film. Stretching can be performed after dyeing with iodine, or it can be stretched while dyeing, or it can be dyed with iodine after stretching. Stretching can be performed in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

In addition, in the present invention, a thin polarizer having a thickness of 10 μm or less can also be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. Such a thin polarizer has little thickness unevenness, excellent visibility, and excellent durability due to little dimensional change, and is also preferable in that the thickness of the polarizing film can be made thin.

Representative examples of thin polarizers include the thin polarizing films described in JP-A-51-069644, JP-A-2000-338329, WO-A-2010/100917, WO-A-2010/100917, or Japanese Patent No. 4751481 and JP-A-2012-073563. These thin polarizing films 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 substrate 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 resin substrate for stretching.

As the thin polarizing film, among the manufacturing methods including the steps of stretching and dyeing the laminate, those obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in WO 2010/100917, WO 2010/100917, or Japanese Patent No. 4751481 and JP 2012-073563 are preferred, because they can be stretched at a high ratio and have improved polarization performance. In particular, those obtained by a manufacturing method including a step of auxiliary air-stretching before stretching in an aqueous boric acid solution as described in Japanese Patent No. 4751481 and JP 2012-073563 are preferred.

(3-3) Transparent protective film on the image display side As the transparent protective film on the image display side, a conventionally used one can be appropriately used. Specifically, a transparent protective film formed from a material excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. is preferable, and examples thereof include polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin), polycarbonate-based polymers, etc. Examples of the polymer forming the transparent protective film include polyethylene, polypropylene, polyolefins having a cyclo- or norbornene structure, polyolefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamides, imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and blends of the above polymers. The transparent protective film can also be formed as a cured layer of a thermosetting or ultraviolet-curing resin such as an acrylic, urethane, acrylic urethane, epoxy, or silicone.

The thickness of the protective film on the image display side can be determined as appropriate, but is generally about 1 to 500 μm, taking into consideration strength, ease of handling, thinness, etc.

The polarizer and the transparent protective film on the image display side are also usually adhered to each other via a water-based adhesive. Examples of water-based adhesives include those mentioned above.

The surface of the transparent protective film on the image display section side to which the polarizer is not attached may be provided with a hard coat layer, anti-reflection treatment, anti-sticking treatment, or treatment for diffusion or anti-glare purposes.

2. Image Display Device The image display device of the present invention is characterized by using the pressure-sensitive adhesive layer-attached polarizing film of the present invention.

As an example of a specific configuration of an image display device, for example, as shown in Figures 2 to 4, a cover glass or cover plastic 6/visual side adhesive layer 2a/visual side transparent protective film 3a/polarizer 4/image display section side transparent protective film 3b/image display section side adhesive layer 2b/liquid crystal display device (LCD) or organic EL display device (OLED) 7 (Figure 2); cover glass or cover plastic 6/adhesive layer 8a/sensor layer 9/visual side adhesive layer 2a/visual side transparent protective film 3a/polarizer 4/image display section side transparent protective film Examples of image displays in which the layers are laminated in this order include: cover glass or cover plastic 6/adhesive layer 8a/sensor layer 9/adhesive layer 8b/sensor layer 9/viewer-side adhesive layer 2a/viewer-side transparent protective film 3a/polarizer 4/image-display-part-side transparent protective film 3b/image-display-part-side adhesive layer 2b/liquid crystal display device (LCD) or organic EL display device (OLED) 7 (FIG. 3); cover glass or cover plastic 6/adhesive layer 8a/sensor layer 9/adhesive layer 8b/sensor layer 9/viewer-side adhesive layer 2a/viewer-side transparent protective film 3a/polarizer 4/image-display-part-side transparent protective film 3b/image-display-part-side adhesive layer 2b/liquid crystal display device (LCD) or organic EL display device (OLED) 7 (FIG. 4). The adhesive layer-attached polarizing film 1 of the present invention refers to the portion of "viewer-side adhesive layer 2a/viewer-side transparent protective film 3a/polarizer 4/image-display-part-side transparent protective film 3b/image-display-part-side adhesive layer 2b" in the above-mentioned configuration, and may also include a retardation film and the like in addition to these. In addition, when a retardation film is included, specifically, a pressure-sensitive adhesive layer can be laminated between the image display unit side pressure-sensitive adhesive layer 2b and the liquid crystal display device (LCD) or organic electroluminescence display device (OLED) 7. In addition, a pressure-sensitive adhesive layer and/or adhesive layer can be used as appropriate in laminating each layer.

Examples of image display devices include liquid crystal display devices, organic EL (electroluminescence) display devices, PDPs (plasma display panels), electronic paper, etc., but among these, liquid crystal display devices and organic EL (electroluminescence) display devices having the above-mentioned configurations are preferred.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples. Note that all parts and percentages in each example are by weight. The evaluation items in the examples were measured as follows.

Production Example 1 (Production of Acrylic Pressure-Sensitive Adhesive Composition (a-1))
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) was mixed with 0.035 parts by weight of 1-hydroxycyclohexyl phenyl ketone (product name: Irgacure 184, having an absorption band at a wavelength of 200 to 370 nm, manufactured by BASF) and 0.035 parts by weight of 2,2-dimethoxy-1,2-diphenylethan-1-one (product name: Irgacure 651, having an absorption band at a wavelength of 200 to 380 nm, manufactured by BASF) as photopolymerization initiators, and then irradiated with ultraviolet light until the viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30° C.) reached about 20 Pa·s, to obtain a prepolymer composition (polymerization rate: 8%) in which a portion of the monomer components was polymerized. Next, 0.15 parts by weight of hexanediol diacrylate (HDDA) and 0.3 parts by weight of a silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to the prepolymer composition and mixed to obtain an acrylic pressure-sensitive adhesive composition (a-1).

Production Example 2 (Production of acrylic pressure-sensitive adhesive composition (a-2))
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-diphenyl-1-one (product name: Irgacure 651, having an absorption band at a wavelength of 200 to 380 nm, manufactured by BASF Japan) as a photopolymerization initiator, and 0.05 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (product name: Irgacure 184, having an absorption band at a wavelength of 200 to 370 nm, manufactured by BASF Japan) were charged into a four-neck flask, and the mixture was exposed to ultraviolet light under a nitrogen atmosphere to partially photopolymerize, thereby obtaining a partially polymerized product (monomer syrup) with a polymerization rate of 10%. Next, 0.15 parts by weight of dipentaerythritol penta- and hexaacrylate (DPHA) and 0.3 parts by weight of a silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to the partially polymerized product, mixed, and irradiated with ultraviolet light to obtain an acrylic pressure-sensitive adhesive composition (a-2).

Production Example 3 (Production of Pressure-Sensitive Adhesive Layer (B-1) on Image Display Section)
Into a separable flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, 95 parts of butyl acrylate, 5 parts of acrylic acid, 0.2 parts of azobisisobutyronitrile as a polymerization initiator, and 233 parts of ethyl acetate were charged, and then nitrogen gas was introduced and nitrogen substitution was performed for about 1 hour while stirring. Thereafter, the flask was heated to 60°C and reacted for 7 hours to obtain an acrylic polymer with a weight average molecular weight (Mw) of 1,100,000.
To the above acrylic polymer solution (solid content: 100 parts by weight), 0.8 parts by weight of trimethylolpropane tolylene diisocyanate (product name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) as an isocyanate crosslinking agent and 0.1 parts of a silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to prepare a pressure-sensitive adhesive composition (solution).
The obtained pressure-sensitive adhesive composition solution was applied onto a 38 μm-thick separator (a polyethylene terephthalate film with a release-treated surface) so that the thickness after drying would be 12 μm, and the layer was dried at 100° C. for 3 minutes to remove the solvent, obtaining a pressure-sensitive adhesive layer. Thereafter, the layer was heated at 50° C. for 48 hours to carry out a crosslinking treatment. Hereinafter, this pressure-sensitive adhesive layer will be referred to as "image display portion side pressure-sensitive adhesive layer (B-1)."

Production Example 4 (Production of Pressure-Sensitive Adhesive Layer (B-2) on Image Display Section)
The adhesive composition solution obtained in Production Example 3 was applied onto a 38 μm thick separator (a polyethylene terephthalate film with a release-treated surface) so that the thickness after drying would be 15 μm, and the layer was dried at 100° C. for 3 minutes to remove the solvent, obtaining an adhesive layer. Thereafter, the layer was heated at 50° C. for 48 hours to carry out a crosslinking treatment. Hereinafter, this adhesive layer will be referred to as "image display portion side adhesive layer (B-2)".

Example 1
(Production of pressure-sensitive adhesive composition with ultraviolet absorbing function)
To the obtained acrylic pressure-sensitive 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 Ltd.) dissolved in butyl acrylate to a solid content of 15% and 0.2 parts of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure 819, having absorption resistance in the wavelength range of 200 to 450 nm, manufactured by BASF Japan Ltd.) were added and stirred to obtain a pressure-sensitive adhesive composition with ultraviolet absorbing function.

The pressure-sensitive adhesive composition with ultraviolet absorbing function was applied onto a release-treated film of a release film so that the thickness of the pressure-sensitive adhesive layer after formation was 150 μm, and then a release film was attached to the surface of the pressure-sensitive adhesive composition layer. Thereafter, the pressure-sensitive adhesive composition layer was photocured by irradiating with ultraviolet light under conditions of illuminance: 6.5 mW/cm ² and light amount: 1500 mJ/cm ² to form a visible-side pressure-sensitive adhesive layer (A-1).

(Production of Polarizing Film (P-1))
A 25 μm-thick triacetyl cellulose film was attached to the viewing side of a polarizer made of a 12 μm-thick stretched polyvinyl alcohol film impregnated with iodine using a polyvinyl alcohol-based adhesive, and a 20 μm-thick acrylic film was laminated to the image display side surface of the polarizer using a polyvinyl alcohol-based adhesive to obtain a polarizing film (P-1). The polarization degree of the polarizing film was 99.995.

(Production of polarizing film with adhesive layer)
A viewing-side pressure-sensitive adhesive layer (A-1) was laminated on the viewing side of the polarizing film (P-1) (i.e., the surface of a 25 μm-thick triacetyl cellulose film). An image display section-side pressure-sensitive adhesive layer (B-1) was laminated on the image display section-side surface of the polarizing film (P-1) (i.e., the surface of an acrylic film having a thickness of 20 μm), and a retardation film (thickness: 56 μm, material: polycarbonate) and an image display section-side pressure-sensitive adhesive layer (B-2) were further laminated to form a polarizing film with a pressure-sensitive adhesive layer. The obtained polarizing film with a pressure-sensitive adhesive layer had a configuration of viewing-side pressure-sensitive adhesive layer (A-1)/polarizing film (P-1)/image display section-side pressure-sensitive adhesive layer (B-1)/retardation film/image display section-side pressure-sensitive adhesive layer (B-2).

Examples 2 to 10
A polarizing film with a pressure-sensitive adhesive layer was formed in the same manner as in Example 1, except that the amount of the ultraviolet absorbing agent added and the thickness of the pressure-sensitive adhesive layer on the viewing side after formation were as shown in Table 1.

Examples 11 to 13
A polarizing film with a pressure-sensitive adhesive layer was formed in the same manner as in Examples 1 to 3, except that the retardation film and the pressure-sensitive adhesive layer (B-2) on the image display portion side were not formed.

Comparative Examples 1 to 4
A polarizing film with a pressure-sensitive adhesive layer was formed in the same manner as in Examples 11 and 1, except that the type of polarizing film used was as shown in Table 1 and the pressure-sensitive adhesive layer on the viewing side was not formed. The polarizing film (P-2) was as follows.

(Production of Polarizing Film (P-2))
A 60 μm-thick triacetyl cellulose film was attached to the viewing side of a polarizer made of a 12 μm-thick stretched polyvinyl alcohol film impregnated with iodine using a polyvinyl alcohol-based adhesive, and a 40 μm-thick triacetyl cellulose film was laminated to the image display side surface of the polarizer using a polyvinyl alcohol-based adhesive to obtain a polarizing film (P-2). The polarization degree of the polarizing film was 99.995.

Comparative Examples 5 to 8
A polarizing film with a pressure-sensitive adhesive layer was formed in the same manner as in Examples 11 and 1, except that the type of acrylic pressure-sensitive adhesive composition forming the visible-side pressure-sensitive adhesive layer and the amount of UV absorber added were as shown in Table 1.

The following evaluations were carried out on the resulting adhesive layer and polarizing film with adhesive layer.

<Polymerization rate>
The release film of the visible-side adhesive layer used in the examples and comparative examples was peeled off, and only the visible-side adhesive layer was placed on the weighed aluminum petri dish. The weight of (aluminum petri dish + visible-side adhesive layer) was measured to determine the weight of the adhesive layer before drying. After drying at 130°C for 2 hours and cooling at room temperature for about 20 minutes, the weight of (aluminum petri dish + adhesive) was measured again to determine the weight of the visible-side adhesive layer after drying. The polymerization rate was calculated using the following formula.

<Gel Fraction>
About 0.1 g was taken from the visible-side pressure-sensitive adhesive layer used in the examples and comparative examples, wrapped in a porous tetrafluoroethylene sheet (trade name: NTF1122, manufactured by Nitto Denko Corporation) having an average pore size of 0.2 μm, and then tied with a kite string. The weight at that time was measured (Zg), and this weight was taken as the weight before immersion. The weight before immersion was the total weight of the visible-side pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer collected above), the tetrafluoroethylene sheet, and the kite string. The total weight of the tetrafluoroethylene sheet and the kite string was also measured (Yg). Next, the visible-side pressure-sensitive adhesive layer wrapped in the tetrafluoroethylene sheet and tied with the kite string (referred to as "sample") was placed in a 50 mL container filled with ethyl acetate and left to stand at 23° C. for 7 days. The sample (after the ethyl acetate treatment) was then removed from the container, transferred to an aluminum cup, and dried in a dryer at 130° C. for 2 hours to remove the ethyl acetate, after which the weight was measured (X g) and this weight was taken as the weight after immersion. The gel fraction was calculated from the following formula:
Gel fraction (wt%)=(X−Y)/(Z−Y)×100

<Measurement of transmittance and b* value of visible side pressure-sensitive adhesive layer>
The release film of the visible side pressure-sensitive adhesive layer used in the examples and comparative examples was peeled off, and the visible side pressure-sensitive adhesive layer was attached to a measuring jig and measured with a spectrophotometer (product name: U4100, manufactured by Hitachi High-Technologies Corporation).

<Residual stress>
A test piece was prepared by cutting out a piece of 30 mm wide and 50 mm long from the visible side pressure-sensitive adhesive layer used in the examples and comparative examples, and forming it into a cylindrical shape. This was placed with a chuck gap of 20 mm, and the test piece was pulled 60 mm (300%) at a pulling speed of 200 mm/min (the chuck gap after pulling was 80 mm). The test piece was fixed (held) at the position where it was pulled 60 mm for 300 seconds, and the stress value (N) after 300 seconds was measured. The residual stress was calculated using the following formula.
Residual stress after 300 seconds = stress value after 300 seconds (N) / (4 × thickness of test piece / 10)

<Optical reliability>
Both sides of the polarizing film with the adhesive layer obtained in the examples and comparative examples were laminated with glass (product name: S200200, thickness: 1.3 mm, size: 45 mm x 50 mm, manufactured by Matsunami Glass Industry Co., Ltd.), and then autoclaved for 15 minutes (atmospheric pressure: 0.5 MPa, temperature: 50°C). For comparative examples 1 to 4, the adhesive layer on the image display unit side of the polarizing film or retardation film was laminated with the above glass, and the same autoclaving was performed as above. Thereafter, the film was placed under the following various reliability conditions, and the transmittance was measured with an ultraviolet-visible-near infrared spectrophotometer (product name: V7100, manufactured by JASCO Corporation). The amount of change in transmittance from the initial state was determined. Evaluation was performed according to the following evaluation criteria.
(Various reliability conditions)
(Condition 1) 85°C x 500h
(Condition 2) 60°C, 95% x 500h
(Condition 3) Heat shock (HS) (-40°C to 85°C) x 300 cycles (Condition 4) Under UV irradiation x 100 hours, illuminance: 500 W/cm ² (300 to 700 nm), environmental temperature: 60 to 65°C, environmental humidity: 50%
(Evaluation criteria)
A: The change in transmittance is 2.0% or less.
Δ: The amount of change in transmittance is more than 2.0% and is 3.0% or less.
×: The change in transmittance exceeds 3.0%.

<Glue stains, dimensional accuracy, edge appearance>
The polarizing film with the adhesive layer obtained in the examples and comparative examples was cut into a size of 25 mm x 30 mm using a super cutter. Then, the four sides of the cut pieces were cut by 0.05 mm using an edge processing machine (Megalo Technica Co., Ltd.) to obtain samples. The sides of the samples were visually inspected for glue stains to confirm the presence or absence of glue stains. The dimensional accuracy and edge appearance were observed using an optical microscope and evaluated according to the following evaluation criteria.
(Dimensional accuracy)
○: Within ±0.3 mm ×: Exceeds ±0.3 mm (Appearance of end)
○: When the edge is not sticky when touched with the hand ×: When the edge is sticky when touched with the hand

In Table 1, P-1 represents the polarizing film (P-1), P-2 represents the polarizing film (P-2), a-1 represents the acrylic pressure-sensitive adhesive composition (a-1) obtained in Production Example 1, a-2 represents the acrylic pressure-sensitive adhesive composition (a-2) obtained in Production Example 2, B-1 represents the pressure-sensitive adhesive layer on the image display portion (B-1) obtained in Production Example 3, and B-2 represents the pressure-sensitive adhesive layer on the image display portion (B-2) obtained in Production Example 4.

REFERENCE SIGNS LIST 1 Polarizing film with adhesive layer 2a Visible-side adhesive layer 2b Image display section side adhesive layer 3a Visible-side transparent protective film 3b Image display section side transparent protective film 4 Polarizer 5 Polarizing film 6 Cover glass or cover plastic 7 Liquid crystal display device (LCD) or organic electroluminescence display device (OLED)
8a, 8b Adhesive layer 9 Sensor layer

Claims (7)

A polarizing film with a pressure-sensitive adhesive layer for use on a viewing side of an image display unit in an image display device,
The pressure-sensitive adhesive layer-attached polarizing film has a polarizing film and pressure-sensitive 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 viewing side of the polarizer has a transmittance at a wavelength of 380 nm of 6% or more and 30% or less,
the transparent protective film on the viewing side of the polarizer is at least one film selected from the group consisting of a triacetyl cellulose film, an acrylic film, a polyethylene terephthalate film, and a polyolefin film having a cyclo- or norbornene structure, and has a thickness of 30 μm or less;
the transparent protective film on the image display portion side of the polarizer has a thickness of 1 to 20 μm, and the pressure-sensitive adhesive layer on the viewing side of the polarizing film has an ultraviolet absorbing function,
The pressure-sensitive adhesive layer on the viewing side of the polarizing film has a gel fraction of 75% or more and 89% or less,
A polarizing film with an adhesive layer, wherein the adhesive layer on the viewing side of the polarizing film has a transmittance of 40% or less at a wavelength of 380 nm and a transmittance of 30% or more at a wavelength of 400 nm. The polarizing film with adhesive layer according to claim 1, characterized in that the thickness of the adhesive layer on the viewing side of the polarizing film is at least twice the thickness of the adhesive layer on the image display side of the polarizing film. The polarizing film with an adhesive layer according to claim 1 or 2, characterized in that the b* value of the adhesive layer on the viewing side of the polarizing film is 3.0 or less. The polarizing film with an adhesive layer according to any one of claims 1 to 3, characterized in that the adhesive layer on the viewing side of the polarizing film contains an acrylic polymer as a base polymer. The polarizing film with an adhesive layer according to any one of claims 1 to 4, characterized in that it is used in a liquid crystal display device or an organic EL display device. An image display device characterized in that the polarizing film with the adhesive layer according to any one of claims 1 to 5 is used on the viewing side of the image display section. The polarizing film with an adhesive layer according to any one of claims 1 to 5, characterized in that the adhesive layer on the viewing side of the polarizing film is formed from an ultraviolet polymer of an ultraviolet-curable acrylic adhesive composition containing a monomer component containing alkyl (meth)acrylate and/or a partial polymer of the monomer component, an ultraviolet absorber, and a photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more.