JP2022085851A - Coating-type polarizing element adhesive composition, coating-type polarizing element adhesive sheet, adhesive sheet with polarizing element, and image display device - Google Patents

Abstract

To provide a coating-type polarizing element adhesive composition and an adhesive sheet, which prevent temporal deterioration of polarizing performance of a coating-type polarizing element due to exposure to light when used in combination with the coating-type polarizing element.SOLUTION: A coating-type polarizing element adhesive composition is provided, comprising a (meth)acrylic polymer (A), an ultraviolet absorber (B), and a radical polymerization initiator (C). An adhesive layer formed from the adhesive composition exhibits a transmittance of 50% or less at a wavelength of 400 nm. A coating-type polarizing element adhesive sheet comprising the adhesive layer formed from the composition is also provided.SELECTED DRAWING: None

Description

The present invention relates to a pressure-sensitive adhesive composition that can be suitably used for organic electroluminescence (hereinafter, also referred to as "organic EL"). In particular, a pressure-sensitive adhesive composition that can be suitably used for a coating-type polarizing element, a pressure-sensitive adhesive sheet for a coating-type polarizing element formed from the pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet with a polarizing element provided with a coating-type polarizing element, and the pressure-sensitive adhesive. The present invention relates to an image display device using a sheet, a coating type polarizing element with a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, and an image display device using the coating-type polarizing element with the pressure-sensitive adhesive layer.

In recent years, along with the trend toward thinner and lighter image display devices such as liquid crystal displays and organic EL display devices, the thinning of optically anisotropic members such as polarizing plates and retardation plates constituting the image display device has also been made. It has been demanded.
Conventional polarizing plates generally have a structure in which a polyvinyl alcohol (PVA) film is sandwiched between protective films such as a TAC (triacetyl cellulose) film, and an adhesive is applied or an adhesive sheet is laminated. It was a target. For example, an adhesive layer / protective film / polarizing film (polarizer) / protective film / adhesive layer / or an adhesive layer / protective film / polarizing film (polarizer) / retardation plate / adhesive layer / etc. A polarizing plate having a laminated structure has been known.

However, such a conventional polarizing plate is very brittle because it uses a polarizing element obtained by stretching a polyvinyl alcohol (PVA) film, and it is necessary to sandwich it between two protective films, so that it is limited to thinning. was there.
Therefore, the following coating type polarizing elements are attracting attention as means for reducing the thickness of polarizing elements such as polarizing plates.
A liquid crystal compound having a polymerizable functional group (also referred to as a "polymerizable liquid crystal compound") has both properties as a polymerizable monomer and properties as a liquid crystal. A cured product made of a polymer having a fixed orientation, that is, an optically anisotropic material can be obtained.
Therefore, a polarizing film having optical anisotropy can be formed by applying an optically anisotropic composition containing a polymerizable liquid crystal compound to a substrate and curing it in an oriented state. The polarizing element thus obtained is generally often referred to as a coating type polarizing element.

On the other hand, there is known an adhesive sheet containing an ultraviolet absorber, which is arranged between a surface protection panel and an image display module in order to suppress photodegradation of an image display device component.
For example, Patent Document 1 discloses a pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer, b ^* of 0.42 or less, and a light transmittance of 5% or less at a wavelength of 350 nm.
Further, in Patent Document 2, the transmittance at a wavelength of 380 nm or less and the transmittance at a wavelength of 400 nm, which is arranged between the cover glass or the cover plastic in the image display device and the polarizing film, is 40% or more and is 30% or more. The ultraviolet curable acrylic pressure-sensitive adhesive layer is disclosed.

Japanese Unexamined Patent Publication No. 2019-214722 Japanese Unexamined Patent Publication No. 2016-155981

Since the coating type polarizing element as described above can form a film by coating as compared with the conventional polarizing element, the thickness can be reduced.
However, since such a coating type polarizing element is easily deteriorated by light, there is a problem that the polarizing performance is deteriorated with time by light such as external light.
Further, not only the polarizing element but also various optical members such as iodine used for the polarizing plate, an organic dye having dichroism, a liquid crystal panel used for an image display device, an organic EL element, and the like have a problem that the light resistance is not sufficient. there were.

Therefore, it is conceivable to use the pressure-sensitive adhesive sheet containing an ultraviolet absorber as described above for the coating type polarizing element.
However, since the transparent pressure-sensitive adhesive for an image display device having the light absorption functions of Patent Documents 1 and 2 is not considered to be used in combination with the coating type polarizing element, it is applied when used for the coating type polarizing element. It has been difficult to prevent the polarizing performance of the type polarizing element from deteriorating with time due to light such as external light.

An object of the present invention is an adhesive composition for a coated polarizing element, which can be used in combination with a coated polarizing element to prevent the coating type polarizing element from deteriorating its polarization performance over time due to exposure. Or to provide an adhesive sheet.

In order to solve this problem, the present invention is a pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A), an ultraviolet absorber (B) and a radical polymerization initiator (C), from the pressure-sensitive adhesive composition. We propose a pressure-sensitive adhesive composition for a coating type polarizing element in which the transmittance of the formed pressure-sensitive adhesive layer at a wavelength of 400 nm is 50% or less.

When the pressure-sensitive adhesive composition for a coating-type polarizing element or the pressure-sensitive adhesive sheet for a coating-type polarizing element of the present invention is used in combination with the coating-type polarizing element, the coating-type polarizing element is subjected to aging due to light such as external light. It is possible to prevent the decrease in the target. Therefore, unlike the conventional case, the coating type polarizing element can be bonded and integrated with other image display device components without using a protective film, and photodegradation can be prevented, so that the image display device can be used. It can contribute to thinning, weight reduction, and improvement of photodegradability.

It is sectional drawing which shows an example of the adhesive sheet with a polarizing element of this invention. It is sectional drawing which shows an example of the image display apparatus of this invention. It is sectional drawing which shows an example of the image display apparatus of this invention. It is sectional drawing which shows an example of the image display apparatus of this invention. It is sectional drawing which shows an example of the adhesive sheet with a mold release film of this invention. It is sectional drawing which shows an example of the laminated sheet of this invention.

Next, the present invention will be described based on examples of embodiments. However, the present invention is not limited to the embodiments described below.

<< This Adhesive Composition >>
The pressure-sensitive adhesive composition for a coated polarizing element (referred to as “the present pressure-sensitive adhesive composition”) according to an example of the embodiment of the present invention is a (meth) acrylic polymer (A), an ultraviolet absorber (B) and a radical. It contains a polymerization initiator (C), and if necessary, contains a polyfunctional (meth) acrylate (D) and other components.

In the present invention, "(meth) acrylic polymer" means to include acrylic copolymer and methacrylic copolymer, and "(meth) acrylate" includes acrylate and methacrylate. "(Meta) acryloyl" means to include acryloyl and methacrylic acid.
Further, in the present invention, the "polarizing element" means an optical member having optical anisotropy, and the "coating type polarizing element" is formed by applying an optically anisotropic composition containing a liquid crystal compound. It means a laminated body containing a film to be formed. Examples of the liquid crystal compound include polymerizable liquid crystal compounds, polymer liquid crystal compounds, and lyotropic liquid crystal compounds. For example, a cured product obtained by applying an optically anisotropic composition containing a polymerizable liquid crystal compound to a substrate and curing it in an oriented state can be used as a polarizing element. At this time, the base material may or may not be contained.

As will be described later, the present pressure-sensitive adhesive composition may be cured by heat or may be cured by active energy rays. In particular, those cured by active energy rays are preferable in that they do not require aging and are excellent in productivity.
The present pressure-sensitive adhesive composition may be one that can be cured in multiple stages, as will be described later.

In addition, when curing with active energy rays, in the case of an adhesive sheet containing an ultraviolet absorber, it is usually difficult to adopt an active energy ray curing system because the ultraviolet absorber interferes with curing with active energy rays. However, when the present invention was intentionally applied, a good pressure-sensitive adhesive sheet could be obtained.

<(Meta) acrylic polymer (A)>
Examples of the (meth) acrylic polymer (A) include homopolymers of alkyl (meth) acrylates and copolymers obtained by polymerizing this with a copolymerizable monomer component. ..

Examples of the copolymer include a copolymer of an alkyl (meth) acrylate (a1) having an alkyl group having 4 to 18 carbon atoms as a main component and a monomer component copolymerizable therewith. can.
The above-mentioned main component means a component that has a great influence on the characteristics of the (meth) acrylic polymer (A), and the content of the component is usually the (meth) acrylic polymer (A). ) 30% by mass or more, preferably 35% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more.

The (meth) acrylic polymer (A) may contain two or more different types of (meth) acrylic polymers.

Examples of the above-mentioned "alkyl (meth) acrylate (a1) having 4 to 18 carbon atoms in the alkyl group" include n-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, and heptyl (meth) acrylate. , N-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate , Linear alkyl (meth) acrylate such as stearyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, Branched alkyl (meth) acrylates such as 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, t- Butylcyclohexyl (meth) acrylate, 3,5,5-trimethylcyclohexane (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) ) An alicyclic (meth) acrylate such as acrylate can be mentioned. These may be used alone or in combination of two or more.

The content of the alkyl (meth) acrylate (a1) is the entire component of the (meth) acrylic polymer (A) from the viewpoint of improving stress relaxation property and heat resistance reliability when the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer is used. It is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, particularly preferably 60% by mass or more, and most preferably 65% by mass or more.
Further, the content of the alkyl (meth) acrylate (a1) may be 90% by mass or less with respect to the entire component of the (meth) acrylic polymer (A) from the viewpoint of suppressing the decrease in adhesive strength. It is preferably more preferably 85% by mass or less, further preferably 80% by mass or less, particularly preferably 75% by mass or less, and most preferably 70% by mass or less.

Examples of the monomer component copolymerizable with the alkyl (meth) acrylate (a1) having 4 to 18 carbon atoms of the alkyl group include the hydroxy group-containing monomer (a2) and the alkyl group having 1 to 3 carbon atoms. (Meta) acrylate monomer or vinyl ester-based monomer (a3), functional group-containing ethylenically unsaturated monomer (a4) (excluding hydroxy group-containing monomer (a2)), other copolymerizable monomer (a5), etc. Can be mentioned.

Examples of the above-mentioned "hydroxy group-containing monomer (a2)" include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. , Hydroxy (meth) acrylate such as 8-hydroxyoctyl (meth) acrylate, caprolactone-modified monomer such as caprolactone-modified 2-hydroxyethyl (meth) acrylate, oxyalkylene-modified such as diethylene glycol (meth) acrylate and polyethylene glycol (meth) acrylate. Primary hydroxy group-containing monomers such as monomers, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro2-hydroxypropyl ( Secondary hydroxy group-containing monomers such as meta) acrylate; tertiary hydroxy group-containing monomers such as 2,2-dimethyl2-hydroxyethyl (meth) acrylate can be mentioned. These can be used alone or in combination of two or more.

Among the hydroxy group-containing monomers (a2), primary hydroxy group-containing monomers, particularly 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate, 2 are excellent in the balance between moist heat resistance and heat resistance. -Hydroxypropyl (meth) acrylates, particularly 2-hydroxyethyl (meth) acrylates and 4-hydroxybutyl (meth) acrylates are preferred.

The lower limit of the content of the hydroxy group-containing monomer (a2) is usually 3 parts by mass or more, preferably 3 parts by mass or more, with respect to the entire component of the (meth) acrylic polymer (A) from the viewpoint of improving the moist heat resistance. Is 5 parts by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, and particularly preferably 12% by mass or more.
On the other hand, the upper limit of the content of the hydroxy group-containing monomer (a2) is usually 60% by mass or less from the viewpoint of suppressing the self-crosslinking reaction of the pressure-sensitive adhesive composition and improving processability and heat resistance reliability. It is preferably 45% by mass or less, more preferably 35% by mass or less, still more preferably 30% by mass or less, and particularly preferably 25% by mass or less.

Examples of the above-mentioned "(meth) acrylate monomer or vinyl ester-based monomer (a3) having 1 to 3 carbon atoms in the alkyl group" include methyl (meth) acrylate, ethyl (meth) acrylate, and n-propyl (meth). Examples thereof include acrylate, isopropyl (meth) acrylate, vinyl propionate, vinyl acetate and the like. These monomers (a3) may be used alone or in combination of two or more.
Among the above components (a3), it is preferable to use methyl (meth) acrylate or ethyl (meth) acrylate from the viewpoint of improving the cohesive force when used as a pressure-sensitive adhesive.

Further, the lower limit of the content when the component (a3) is contained is set with respect to the entire component of the (meth) acrylic polymer (A) from the viewpoint of improving the cohesive force when used as a pressure-sensitive adhesive. It is preferably 5% by mass or more, more preferably 7% by mass or more, and further preferably 10% by mass or more. Further, the upper limit of the content when the component (a3) is contained is 40% by mass or less with respect to the entire component of the (meth) acrylic polymer (A) from the viewpoint of improving processability. It is preferable, more preferably 30% by mass or less, still more preferably 20% by mass or less.

Examples of the above-mentioned "functional group-containing ethylenically unsaturated monomer (a4)" include a functional group-containing monomer having a nitrogen atom, a carboxy group-containing monomer, an acetoacetyl group-containing monomer, an isocyanate group-containing monomer, and a glycidyl group-containing monomer. Can be mentioned.
Among these, a functional group-containing monomer having a nitrogen atom is preferable, an amino group-containing monomer and an amide group-containing monomer are more preferable, and an amino group-containing monomer is more preferable, in terms of imparting a cohesive force and a cross-linking promoting action. be.

The "amino group-containing monomer" as the "functional group-containing monomer having a nitrogen atom" includes, for example, a primary amino group-containing (meth) acrylate such as aminomethyl (meth) acrylate and aminoethyl (meth) acrylate. Secondary amino group-containing (meth) acrylates such as t-butylaminoethyl (meth) acrylate and t-butylaminopropyl (meth) acrylate; ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylamino Examples thereof include tertiary amino group-containing (meth) acrylates such as ethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, and dimethylaminopropylacrylamide.

Examples of the "amide group-containing monomer" include (meth) acrylamide; N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, and N-n-butyl (meth) acrylamide. , N-alkyl (meth) acrylamide such as diacetone (meth) acrylamide, N, N'-methylenebis (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N, N-dialkyl (meth) acrylamide such as N-dipropyl (meth) acrylamide, N, N-ethylmethylacrylamide, N, N-diallyl (meth) acrylamide; N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl Hydroxyalkyl (meth) acrylamide such as (meth) acrylamide; alkoxyalkyl (meth) acrylamide such as N-methoxymethyl (meth) acrylamide and N- (n-butoxymethyl) (meth) acrylamide; and the like can be mentioned.

Examples of the "carboxy group-containing monomer" include (meth) acrylic acid, carboxyethyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and 2- (meth) acryloyloxypropyl hexahydrophthalic acid. , 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropyl maleic acid, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropyl maleic acid, 2- (meth) Examples thereof include acryloyloxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, and monomethyl itaconic acid.

Examples of the "acetoacetyl group-containing monomer" include 2- (acetoacetoxy) ethyl (meth) acrylate and allylacetacetate.

Examples of the "isocyanate group-containing monomer" include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof. The isocyanate group may be protected with a blocking agent such as methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, diethyl malonate and the like.

Examples of the "glycidyl group-containing monomer" include glycidyl (meth) acrylate and allyl glycidyl (meth) acrylate.

These functional group-containing ethylenically unsaturated monomers (a4) may be used alone or in combination of two or more.

The upper limit of the content of the functional group-containing ethylenically unsaturated monomer (a4) is applied to the entire component of the (meth) acrylic polymer (A) from the viewpoint of improving the heat resistance and light resistance of the pressure-sensitive adhesive composition. On the other hand, it is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, and particularly preferably 5% by mass or less.

The (meth) acrylic polymer (A) can contain another copolymerizable monomer (a5) as a copolymerization component, if necessary.

Examples of the other copolymerizable monomer (a5) include phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, and phenoxy. Aromatic (meth) acrylic acid ester-based monomers such as polyethylene glycol-polypropylene glycol- (meth) acrylate and nonylphenol ethylene oxide adduct (meth) acrylate, 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4- Acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'- (Meta) acrylic acid ester-based monomers having a benzophenone structure such as bromobenzophenone and mixtures thereof, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, Vinyl-based monomers such as vinylpyridine, vinylpyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, acrylic chloride, methyl vinyl ketone, N-acrylamide methyltrimethylammonium chloride, allyltrimethylammonium chloride, and dimethylallylvinyl ketone. be able to. These can be used alone or in combination of two or more.

The (meth) acrylic polymer (A) may have a photoactive site, for example, a polymerizable carbon double bond group introduced into the side chain. Thereby, even if the present pressure-sensitive adhesive composition does not contain the polyfunctional (meth) acrylate (D), the present pressure-sensitive adhesive composition can be cross-linked by radical polymerization.
In addition, the cross-linking sensitivity of the pressure-sensitive adhesive composition can be increased, and the pressure-sensitive adhesive composition can be cross-linked by irradiation with active energy rays of lower energy to impart cohesive force and heat resistance.

As a method for introducing a polymerizable carbon double bond group into the side chain of the (meth) acrylic polymer (A), for example, the above-mentioned hydroxy group-containing monomer (a2) or functional group-containing ethylenically unsaturated monomer (a4) ) As a copolymerization component, and then a compound (a6) having a functional group capable of reacting with these functional groups and a polymerizable carbon double-bonding group is used as a polymerizable carbon double-bonding group. A method of condensing or performing an addition reaction while maintaining the activity of the above can be mentioned.

The combination of these functional groups includes an epoxy group (glycidyl group) and a carboxy group, an amino group and a carboxy group, an amino group and an isocyanate group, an epoxy group (glycidyl group) and an amino group, a hydroxy group and an epoxy group, and a hydroxy group. Examples thereof include an isocyanate group. Among these combinations of functional groups, a combination of a hydroxy group and an isocyanate group is preferable because of ease of reaction control. Of these, a combination in which the copolymer has a hydroxy group and the compound has an isocyanate group is preferable.
Examples of the isocyanate compound having a polymerizable carbon double bond group include the above-mentioned 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

The amount of the compound (a6) added is preferably 10 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer (A) from the viewpoint of improving the adhesiveness and stress relaxation property. It is preferably 8 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

The mass average molecular weight of the (meth) acrylic polymer (A) is preferably 100,000 or more, more preferably 300,000 or more, from the viewpoint of obtaining the present pressure-sensitive adhesive composition having high cohesive force. It is more preferably 500,000 or more.
Further, the upper limit of the mass average molecular weight of the (meth) acrylic polymer (A) is preferably 2 million or less, preferably 1.5 million, from the viewpoint of obtaining a pressure-sensitive adhesive composition having high fluidity and stress relaxation property. It is more preferably less than or equal to, and even more preferably less than 1 million.

<Ultraviolet absorber (B)>
By containing the ultraviolet absorber (B), the pressure-sensitive adhesive composition can reduce deterioration of the coating type polarizing element due to light.
Since the present pressure-sensitive adhesive composition contains an ultraviolet absorber (B), when it is photocured, it is preferably cured by a light beam having a wavelength other than the absorption wavelength of the ultraviolet absorber (B).

Examples of the ultraviolet absorber (B) include a benzophenone-based ultraviolet absorber containing a benzophenone structure, a benzotriazole-based ultraviolet absorber containing a benzotriazole structure, a triazine-based ultraviolet absorber containing a triazine structure, and a salicylic acid-based ultraviolet ray containing a salicylic acid structure. Examples thereof include an absorbent, a cyanoacrylate-based ultraviolet absorber containing a cyanoacrylate structure, and the like. These UV absorbers can be used alone or in combination of two or more.

Examples of the benzophenone-based ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, and 2-hydroxy. -4-methoxy-5-sulfoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfoxitrihydride benzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2', 4,4'- Tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sodium sulfoxybenzophenone, bis (5-benzoyl-4-hydroxy) Examples thereof include -2-methoxyphenyl) methane, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone and the like.

Examples of the benzotriazole-based ultraviolet absorber include 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, and 2- (2-hydroxy). -3,5-dicumylphenyl) phenylbenzotriazole, 2- (2-hydroxy-3-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2,2'-methylenebis [4- (1,1) 1,3,3-Tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol], 2- (2-hydroxy-3,5-di-tert-butylphenyl) benzotriazole, 2- ( 2-Hydroxy-3,5-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole, 2- (2-hydroxy- 5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-4-octoxyphenyl) benzotriazole, 2,2'-methylenebis ( 4-cumyl-6-benzotriazolephenyl), 2- [2-hydroxy-3- (3,4,5,6-tetrahydrophthalimidemethyl) -5-methylphenyl] benzotriazole and the like can be mentioned.

Examples of the triazine-based ultraviolet absorber include 2- (2-hydroxy-4-methoxyphenyl) -4,6-diphenyl-1,3,5-triazine and 2- (2-hydroxy-4-ethoxyphenyl). -4,6-diphenyl-1,3,5-triazine, 2- (2-hydroxy-4-propoxyphenyl) -4,6-diphenyl-1,3,5-triazine, 2- (2-hydroxy-4) -Butoxyphenyl) -4,6-diphenyl-1,3,5-triazine, 2- (2-hydroxy-4-hexyloxyphenyl) -4,6-diphenyl-1,3,5-triazine, 2-( 2-Hydroxy-4-octyloxyphenyl) -4,6-diphenyl-1,3,5-triazine, 2- (2-hydroxy-4-dodecyloxyphenyl) -4,6-diphenyl-1,3,5 -Triazine, 2- (2-hydroxy-4-benzyloxyphenyl) -4,6-diphenyl-1,3,5-triazine, 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- ( 2,4-Dibutoxyphenyl) -1,3-5-triazine, 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine, 2- (2-hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy-3) -Dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy-3-tri) Decyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy-3- (2) '-Ethyl) hexyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4- (3-octyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine, 2,4-bis (2,4-dimethylphenyl) -6- [2-Hydrazine-4- (3-nonyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine 2,4-bis (2,4-dimethylphenyl) -6 -[2-Hydroxy-4- (3-decyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine, 2- (2-hydroxy-4-acryloyloxyethoxyphenyl) -4,6- Examples thereof include bis (2,4-dimethylphenyl) -1,3,5-triazine.

Examples of the salicylic acid-based ultraviolet absorber include phenylsalicylate, p-tert-butylphenylsalicylate, p-octylphenylsalicylate and the like.

Examples of the cyanoacrylate-based ultraviolet absorber include 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3'-diphenylacrylate and the like.

Among these, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, and a triazine-based ultraviolet absorber are preferable from the viewpoint of effectively suppressing the light reaching the coated polarizing element. Among them, a benzophenone-based ultraviolet absorber containing a benzophenone structure is more preferable from the viewpoint of excellent yellow denaturation resistance.
Furthermore, among them, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2', 4,4'-tetrahydroxy from the viewpoint of being able to block light up to a long wavelength range. Further preferred are dihydroxybenzophenone-based UV absorbers such as benzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sodium sulfoxybenzophenone.

The lower limit of the content of the ultraviolet absorber (B) is preferably 0.1 part by mass or more with respect to 100 parts by mass of the (meth) acrylic polymer (A) from the viewpoint of improving light resistance reliability. It is more preferably 0.5 parts by mass or more, further preferably 1.5 parts by mass or more, particularly preferably 3 parts by mass or more, particularly preferably 5 parts by mass or more, and most preferably 6 parts by mass or more.
On the other hand, the upper limit of the content of the ultraviolet absorber (B) is preferable with respect to 100 parts by mass of the (meth) acrylic polymer (A) from the viewpoint of suppressing bleed-out and improving yellowing resistance. Is 15 parts by mass or less, more preferably 12 parts by mass or less, further preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, and most preferably 7 parts by mass or less.

<Radical polymerization initiator (C)>
The radical polymerization initiator (C) may be any as long as it can release a substance that initiates radical polymerization by at least one of irradiation with active energy rays such as light and heat. In particular, a photoradical polymerization initiator that can initiate a reaction by irradiation with active energy rays such as light is preferable because it does not require aging during curing and is excellent in productivity.

Examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.

On the other hand, photo-radical polymerization initiators are roughly classified into two types according to the radical generation mechanism, and are a photo-cracking type radical polymerization initiator capable of cleaving and decomposing a single bond of the photo-radical polymerization initiator itself to generate radicals. The photo-excited initiator and the hydrogen donor in the system form an excitation complex, which is roughly classified into a hydrogen abstraction type photoradical polymerization initiator capable of transferring the hydrogen of the hydrogen donor.

Of these, the photo-cleavable radical polymerization initiator decomposes to another compound when a radical is generated by light irradiation, and once excited, it loses its function as a reaction initiator. Therefore, it is preferable because it does not remain as an active species in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet after the cross-linking reaction is completed, and there is no possibility of causing unexpected photodegradation or the like in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet.
On the other hand, the hydrogen abstraction type photoradical polymerization initiator can not only maintain its function as a reaction initiator even if it is irradiated with light multiple times, but also it is a photocleavable type during a radical generation reaction by irradiation with an active energy ray such as ultraviolet rays. Since it does not generate a decomposition product such as a radical polymerization initiator, it is less likely to become a volatile component after the reaction is completed, which is useful in that damage to the adherend can be reduced.
Among the above photoradical polymerization initiators, in the present pressure-sensitive adhesive composition, it is preferable to select a photocleavable radical polymerization initiator from the viewpoint of ensuring the light resistance reliability of the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet.

When using a photoradical polymerization initiator, irradiation with visible light, light having wavelengths of at least 390 nm, 405 nm and 410 nm, for example, light in the wavelength region of 380 nm to 700 nm, from the viewpoint of avoiding reaction inhibition by the ultraviolet absorber (B). Therefore, it is preferable to use a visible light initiator that generates radicals and serves as a starting point for the cross-linking reaction of the present pressure-sensitive adhesive composition.
However, the visible light initiator may be one that generates radicals only by irradiation with visible light, or may be one that generates radicals by irradiation with light in a wavelength region other than the visible light region. good.

Examples of the photocleavable radical polymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenylketone, and 2-hydroxy-2-methyl-1-phenyl-propane-. 1-on, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propane-1-one, 2-hirodoxy-1- [4- {4- (2-hydroxy) -2-Methyl-propionyl) benzyl} phenyl] -2-methyl-propane-1-one, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), phenylglyce Methyl oxylicate, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butane-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane- 1-one, 2- (dimethylamino) -2-[(4-methylphenyl) methyl) -1- [4- (4-morpholinyl) phenyl] -1-butanone, bis (2,4,6-trimethylbenzoyl) ) -Phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, derivatives thereof and the like can be mentioned.
Among these, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6), from the viewpoint of decomposing and decolorizing after the reaction. Acylphosphine oxide-based photoinitiators such as -trimethylbenzoyl) ethoxyphenylphosphine oxide and bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine oxide are preferred.

Examples of the hydrogen abstraction type photoradical polymerization initiator include bis (2-phenyl-2-oxoacetic acid) oxybisethylene, phenylglycoxyacid methyl ester, and oxy-phenyl-acetylic acid 2- [2-oxo. Mixture of -2-phenyl-acetoxy-ethoxy] ethyl ester and oxy-phenyl-acetylic acid 2- [2-hydroxy-ethoxy] ethyl ester, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethyl Examples thereof include thioxanthone, anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butyl anthraquinone, 2-aminoanthraquinone, phenylquinone and derivatives thereof.
Among these, phenylglycioxy acid methyl ester, oxy-phenyl-acetylic acid 2- [2-oxo-2-phenyl-acetoxy-ethoxy] ethyl ester and oxy-phenyl-acetylic acid 2- [2-hydroxy- It is preferably any one or two selected from the group consisting of a mixture of ethoxy] ethyl esters.

The photoradical polymerization initiator is not limited to the substances listed above. One of the above-mentioned photoradical polymerization initiators or a derivative thereof may be used, or two or more of them may be used in combination. Further, a visible light initiator and an initiator that generates radicals only by irradiation with other light rays such as ultraviolet rays may be mixed.
A thermal radical polymerization initiator and a photoradical polymerization initiator may be used in combination.

The content of the radical polymerization initiator (C) is not particularly limited, but from the viewpoint of sufficiently advancing the polymerization reaction and improving the shape stability of the pressure-sensitive adhesive sheet, the (meth) acrylic polymer (A). ) 0.1 part by mass or more is preferable, 0.5 part by mass or more is more preferable, 1 part by mass or more is further preferable, and 2 parts by mass or more is particularly preferable.
Further, the upper limit of the content of the radical polymerization initiator (C) is preferably 15 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer (A) from the viewpoint of ensuring the adhesiveness. It is more preferably parts by mass or less, further preferably 6 parts by mass or less, and particularly preferably 4 parts by mass or less.

<Polyfunctional (meth) acrylate (D)>
The pressure-sensitive adhesive composition preferably contains a polyfunctional (meth) acrylate (D), if necessary.
When the present pressure-sensitive adhesive composition contains a polyfunctional (meth) acrylate (D), the present pressure-sensitive adhesive composition forms a crosslinked structure, and the present pressure-sensitive adhesive sheet can be imparted with cohesive force and appropriate toughness. This makes it possible to prevent the surface of the coating type polarizing element from undulating and the pressure-sensitive adhesive layer from being deformed and cracked during cutting when the coating type polarizing element with the pressure-sensitive adhesive layer, which will be described later, is manufactured.

The polyfunctional (meth) acrylate (D) is a compound or composition that forms a crosslinked structure in the present pressure-sensitive adhesive composition, and is a (meth) acrylic monomer or a (meth) acrylic oligomer having two or more functional groups. Can be mentioned.

Examples of the (meth) acrylic monomer include 1,4-butanediol di (meth) acrylate, glycerindi (meth) acrylate, neopentyl glycol di (meth) acrylate, glycering lysidyl ether di (meth) acrylate, and 1,6. -Hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, tricyclodecanedimethacrylate, tricyclodecanedimethanol di (meth) acrylate, bisphenol A polyethoxydi (meth) acrylate, bisphenol A polypropoxy Di (meth) acrylate, bisphenol F polyethoxydi (meth) acrylate, ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropanetrioxyethyl (meth) acrylate, ε-caprolactone-modified tris (2-) Hydroxyethyl) isocyanurate tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, propoxylated penta Elythritol tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) Acrylate, (Tris (acryloxyethyl) isocyanurate, dipentaerythritol penta (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol penta (meth) acrylate, hydroxyviva Neopentyl glycol di (meth) acrylate, di (meth) acrylate of ε-caprolactone adduct of neopen glycol hydroxyvivariate, trimethylol propanetri (meth) acrylate, trimethylol propanepolyethoxytri (meth) acrylate , Ditrimethylol propanetetra (meth) acrylate and the like.
Among them, (meth) acrylic monomers are preferable from the viewpoint of imparting appropriate toughness to the cured product, and among them, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, and polytetramethylene glycol di (meth) are preferable. Polyfunctional (meth) acrylic monomers having an alkylene glycol skeleton such as acrylate are more preferable.

The molecular weight of the (meth) acrylic monomer is preferably 200 or more, more preferably 300 or more, further preferably 400 or more, and particularly preferably 500 or more, from the viewpoint of imparting appropriate flexibility to the cured product. The upper limit of the molecular weight is usually 3000 or less, preferably 2000 or less.

Examples of the (meth) acrylic oligomer include polyfunctional (meth) acrylic oligomers such as polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, and polyether (meth) acrylate. ..
Of these, urethane (meth) acrylate-based oligomers are preferable from the viewpoint of imparting appropriate toughness to the cured product.

Further, when the present pressure-sensitive adhesive composition is cured, a cured product having high toughness can be obtained, in other words, a cured product having appropriate flexibility can be obtained, and a polyfunctional (meth) acrylate can be obtained. As (D), a (meth) acrylic oligomer having a molecular weight of 3000 or more is preferable, and a polyfunctional (meth) acrylate having a molecular weight of 5000 or more, particularly 8000 or more, and particularly 10,000 or more is particularly preferable. The upper limit of the molecular weight is usually 100,000 or less, preferably 50,000 or less.

The mass contained in the polyfunctional (meth) acrylate (D) is a (meth) acrylic weight from the viewpoint of imparting shape stability of the pressure-sensitive adhesive sheet and durability when a laminate is formed from the pressure-sensitive adhesive sheet. 1 part by mass or more is preferable, 2 parts by mass or more is more preferable, 5 parts by mass or more is further preferable, and 10 parts by mass or more is particularly preferable with respect to 100 parts by mass of the coalescence (A).
Regarding the upper limit of the content mass of the polyfunctional (meth) acrylate (D), from the viewpoint of ensuring the adhesiveness, 100 parts by mass or less is preferable with respect to 100 parts by mass of the (meth) acrylic polymer (A). 60 parts by mass or less is more preferable, 40 parts by mass or less is further preferable, and 30 parts by mass or less is particularly preferable.

<Other ingredients>
The present pressure-sensitive adhesive composition may contain, as necessary, as "other components", for example, a tackifier resin, an antioxidant, a light stabilizer, a metal inactivating agent, an antiaging agent, a hygroscopic agent, and a rust preventive agent. , Silane coupling agent, various additives such as inorganic particles can be appropriately contained.
Further, if necessary, a reaction catalyst such as a tertiary amine compound, a quaternary ammonium compound, or a tin laurate compound may be appropriately contained.

<Curable>
The present pressure-sensitive adhesive composition can be cured at one time, or can be cured in multiple stages. That is, it can be cured leaving room for further curing. In terms of gel fraction, the gel fraction of the present pressure-sensitive adhesive composition can be 60% or more in one curing, and the gel fraction is 20 to 60% in the first curing, and further cured. It can also be cured leaving room for it to be cured.
For example, when the present pressure-sensitive adhesive composition has active energy ray curability, it is irradiated with light after being laminated with a coated polarizing element or after being laminated with a coated polarizing element and other image display device components. By curing the present composition, the coating type polarizing element and other image display device constituent members are more firmly adhered to each other, so that the reliability of the laminated body can be improved.
As the light source to be used, ultraviolet rays and visible light are suitable from the viewpoint of suppressing damage to the components of the image display device and controlling the reaction.
The irradiation time and the irradiation means are not particularly limited, but it is preferable to irradiate the light from the surface opposite to the laminated surface of the coating type polarizing element.

Further, the irradiation energy of the active energy ray, the irradiation time, the irradiation method, and the like are not particularly limited, and it is sufficient that the initiator can be activated to polymerize the (meth) acrylate component.

<Light transmittance>
The present pressure-sensitive adhesive composition is derived from the present pressure-sensitive adhesive composition from the viewpoint of preventing light deterioration of the coating-type polarizing element when the pressure-sensitive adhesive layer formed from the present pressure-sensitive adhesive composition is used in combination with the coating-type polarizing element. The transmittance of the formed pressure-sensitive adhesive layer having a thickness of 50 μm at a wavelength of 400 nm is preferably 50% or less, more preferably 40% or less, further preferably 30% or less, and even more preferably 25% or less. Is particularly preferred.

Further, the present pressure-sensitive adhesive composition has the present pressure-sensitive adhesive composition from the viewpoint of preventing light deterioration of the coating-type polarizing element when the pressure-sensitive adhesive layer formed from the present pressure-sensitive adhesive composition is used in combination with the coating-type polarizing element. The transmittance of the pressure-sensitive adhesive layer having a thickness of 50 μm formed from an object at a wavelength of 380 nm is preferably less than 20%, more preferably 5% or less, further preferably 2% or less, and even more preferably 1% or less. Is particularly preferable.

Further, the present pressure-sensitive adhesive composition is formed from the present pressure-sensitive adhesive composition from the viewpoint of ensuring sufficient image visibility when the pressure-sensitive adhesive layer formed from the present pressure-sensitive adhesive composition is used in an image display device. The transmittance of the pressure-sensitive adhesive layer having a thickness of 50 μm at a wavelength of 430 nm is preferably 50% or more, more preferably 60% or more, further preferably 70% or more, and further preferably 80% or more. It is particularly preferable, and it is particularly preferable that it is 85% or more.

<< This adhesive sheet >>
The pressure-sensitive adhesive sheet for a coated polarizing element (referred to as “the present pressure-sensitive adhesive sheet”) according to an example of the embodiment of the present invention is a pressure-sensitive adhesive layer (referred to as “the present pressure-sensitive adhesive layer”) formed by using the present pressure-sensitive adhesive composition. It is an adhesive sheet containing.

The pressure-sensitive adhesive sheet has a single-layer structure composed of the pressure-sensitive adhesive layer formed by using the pressure-sensitive adhesive composition, but has a multi-layer structure having two or more layers having a layer other than the pressure-sensitive adhesive layer. There may be.
When the pressure-sensitive adhesive sheet has a plurality of layers, the composition of the layers other than the layer composed of the pressure-sensitive adhesive composition is arbitrary. However, for example, when the intermediate layer, the outermost layer or the outermost layer is formed by a layer other than the present pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition forming the layer other than the present pressure-sensitive adhesive layer is also used from the viewpoint of further enhancing the interlayer adhesiveness. It is preferably formed from a pressure-sensitive adhesive composition containing a (meth) acrylic polymer as a main component resin, and above all, it is preferable to contain the same (meth) acrylic polymer (A) as the main component resin as the main component resin. More preferred. Furthermore, it is more preferable that the layers other than the present pressure-sensitive adhesive layer also contain a polyfunctional (meth) acrylate and a radical polymerization initiator.

When the pressure-sensitive adhesive sheet has a plurality of layers, it is preferable that at least the outermost layer, the backmost layer, or both layers correspond to the present pressure-sensitive adhesive layer. All layers may be layers corresponding to the present pressure-sensitive adhesive layer.
When the pressure-sensitive adhesive sheet has a plurality of layers, the thickness of the layer corresponding to the pressure-sensitive adhesive layer preferably occupies 10% or more and 100% or less with respect to the total thickness of the pressure-sensitive adhesive sheet. It is more preferable to occupy% or more or 70% or less, and more preferably 20% or more or 50% or less.

(Light transmittance)
From the viewpoint of preventing photodegradation of the coated polarizing element when the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet is used in combination with the coated polarizing element, the light transmittance at a wavelength of 400 nm is preferably 50% or less. It is more preferably 40% or less, further preferably 30% or less, and particularly preferably 25% or less.

Further, from the viewpoint of preventing photodegradation of the coated polarizing element when the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet is used in combination with the coated polarizing element, the transmittance at a wavelength of 380 nm is preferably less than 20%. It is more preferably 5% or less, further preferably 2% or less, and particularly preferably 1% or less.

Further, the adhesive layer to the adhesive sheet preferably has a light transmittance of 50% or more at a wavelength of 430 nm, preferably 60%, from the viewpoint of ensuring sufficient image visibility when used in an image display device. The above is more preferable, 70% or more is further preferable, 80% or more is particularly preferable, and 85% or more is particularly preferable.

(B ^* value)
The b ^* value of the pressure-sensitive adhesive layer to the pressure-sensitive adhesive sheet is preferably 10 or less, more preferably 5 or less, from the viewpoint of suppressing adverse effects on image quality when used in an image display device. It is more preferably 2 or less, and particularly preferably 2 or less.
The above b ^* value is the value of b ^* in the color space of L ^* a ^* b ^* display defined by JIS Z8781-4. When it increases on the positive side, it becomes yellowish, and when it increases on the negative side, it becomes bluish. It means that it becomes achromatic when it approaches 0.

In order to adjust the light transmittance at wavelengths of 380 nm, 400 nm and 430 nm and the b ^* value in the above range in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet, it is necessary to appropriately adjust the type and amount of the ultraviolet absorber in the above range. preferable. However, the method is not limited to this method.

Further, in the present pressure-sensitive adhesive layer to the present pressure-sensitive adhesive sheet, the light transmittance T (380) at a wavelength of 380 nm, the light transmittance T (430) at a wavelength of 430 nm, and the b ^* values are related to the following formulas (I) and (II). It is preferable to satisfy.
0 ≤ T (380) x b ^* ≤ 50 (I)
70 ≤ T (430) x b ^* ≤ 220 (II)

By satisfying the relationship of the above formulas (I) and (II), the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet can achieve both the prevention of photodegradation of the coated polarizing element and the image visibility of the image display device at a higher level. can.
From this point of view, T (380) × b ^* of the above formula (I) is preferably 0 to 50, more preferably 0 to 40, still more preferably 0 to 30, and particularly preferably 0 to 20. ..
The T (430) × b ^* of the above formula (II) is preferably 70 to 220, more preferably 80 or more or 210 or less, still more preferably 90 or more or 200 or less, and particularly preferably 100 or more or It is 190 or less.

(Gel fraction)
The pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet preferably has a gel fraction of 20% or more when used for sticking. When the gel fraction is 20% or more, the shape stability of the pressure-sensitive adhesive sheet and the durability when formed into a laminated body can be imparted.
From this point of view, the gel fraction of the pressure-sensitive adhesive layer to the pressure-sensitive adhesive sheet is more preferably 40% or more, further preferably 50% or more, and particularly preferably 60% or more.
On the other hand, if the gel fraction is 95% or less, even if the adherend is a member having a stepped portion on the surface, the member is filled to every corner by following the stepped portion without causing distortion or deformation. be able to. From this point of view, it is preferably 95% or less, more preferably 85% or less, further preferably 80% or less, and particularly preferably 75% or less.

In order to adjust the gel fraction when used for sticking in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet within the above range, the composition and molecular weight of the (meth) acrylic polymer (A) may be adjusted, or polyfunctionality may be adjusted. It is preferable to adjust the addition amount of the (meth) acrylate (D) and the radical polymerization initiator (C), and adjust the intensity of the activated energy ray to be irradiated and the integrated light amount. However, the method is not limited to this method.

(Thickness)
The thickness of the pressure-sensitive adhesive layer to the pressure-sensitive adhesive sheet is preferably 10 μm or more, more preferably 20 μm or more, further preferably 30 μm or more, and particularly preferably 40 μm or more from the viewpoint of protecting the coating type polarizing element. On the other hand, the upper limit of the thickness is preferably 175 μm or less, more preferably 120 μm or less, further preferably 80 μm or less, and particularly preferably 60 μm or less from the viewpoint of contributing to thinning of the image display device.

<Manufacturing method of this adhesive sheet>
Next, a method for manufacturing the present adhesive sheet will be described. However, the following description is an example of a method for manufacturing the present pressure-sensitive adhesive sheet, and the present pressure-sensitive adhesive sheet is not limited to the one manufactured by such a manufacturing method.

In the production of this pressure-sensitive adhesive sheet, a (meth) acrylic polymer (A), an ultraviolet absorber (B), a radical polymerization initiator (C), and, if necessary, a polyfunctional (meth) acrylate (D). ), Further, if necessary, the present pressure-sensitive adhesive composition is prepared by mixing a predetermined amount of each of the other components, the present pressure-sensitive adhesive composition is formed into a sheet, and the curable compound is crosslinked, that is, if necessary. The present pressure-sensitive adhesive sheet may be produced by subjecting it to a polymerization reaction and curing it. However, the method is not limited to this method.

When preparing the present pressure-sensitive adhesive composition, the above raw materials are kneaded using a temperature-adjustable kneader (for example, a single-screw extruder, a twin-screw extruder, a planetary mixer, a twin-screw mixer, a pressurized kneader, etc.). Just do it.
When mixing various raw materials, the various additives may be blended with the resin in advance and then supplied to the kneader, or all the materials may be melt-mixed in advance and then supplied. A masterbatch in which only the agent is concentrated in a resin in advance may be prepared and supplied.

As a method for forming the present pressure-sensitive adhesive composition into a sheet, known methods such as a wet lamination method, a dry laminating method, an extrusion casting method using a T-die, an extrusion laminating method, a calendar method, an inflation method, injection molding, and Note. A liquid curing method or the like can be adopted. Above all, when producing a sheet, the wet lamination method, the extrusion casting method, and the extrusion laminating method are preferable.

When the present pressure-sensitive adhesive composition contains a radical polymerization initiator (C), a cured product can be produced by irradiating with heat and / or active energy rays and curing. In particular, the pressure-sensitive adhesive sheet can be produced by irradiating a molded body, for example, a sheet body formed with the pressure-sensitive adhesive composition with heat and / or active energy rays.
Here, examples of the active energy rays to be irradiated include ionizing radiation such as α-rays, β-rays, γ-rays, neutron rays, and electron beams, ultraviolet rays, visible rays, and the like, and among them, damage to optical device components. Ultraviolet rays and visible rays are preferable from the viewpoint of suppression and reaction control.
Further, the irradiation energy of the active energy ray, the irradiation time, the irradiation method, and the like are not particularly limited, and it is sufficient that the initiator can be activated to polymerize the (meth) acrylate component.

Further, as another embodiment of the method for producing the present pressure-sensitive adhesive sheet, the present pressure-sensitive adhesive composition may be dissolved in an appropriate solvent and carried out by using various coating methods.
When the coating method is used, the present pressure-sensitive adhesive sheet can be obtained by heat-curing in addition to the above-mentioned active energy ray irradiation curing.

In the case of coating, the thickness of the adhesive sheet can be adjusted by the coating thickness and the solid content concentration of the coating liquid.

<< Adhesive sheet with release film >>
The present adhesive sheet may also be an adhesive sheet with a release film (referred to as "adhesive sheet with a release film") having a structure in which the present adhesive sheet and the release film are laminated.
For example, a single-layer or multi-layered sheet-like pressure-sensitive adhesive layer containing a layer made of the present pressure-sensitive adhesive composition may be formed on the release film to obtain a pressure-sensitive adhesive sheet with a release film (see FIG. 5).

As a material of such a release film, a known release film can be appropriately used.
As the material of the release film, for example, a film such as a polyester film, a polyolefin film, a polycarbonate film, a polystyrene film, an acrylic film, a triacetyl cellulose film, and a fluororesin film is coated with a silicone resin and subjected to a release treatment. A release paper or the like can be appropriately selected and used.
The film may have other layers, such as an antistatic layer, a hard coat layer, and an anchor layer, if necessary.

When the release films are laminated on both sides of the pressure-sensitive adhesive sheet, one release film may have the same laminated structure or material as the other release film, or may have a different laminated structure or material. good.
Further, the thickness may be the same or different.
Further, a release film having a different peeling force and a release film having a different thickness can be laminated on both sides of the pressure-sensitive adhesive sheet.

The thickness of the release film is not particularly limited. Among them, for example, from the viewpoint of processability and handleability, it is preferably 12 μm to 250 μm, and more preferably 25 μm or more or 200 μm or less, and more preferably 38 μm or more or 188 μm or less.

The pressure-sensitive adhesive sheet employs, for example, a method of directly extruding the resin composition or a method of molding by injecting the resin composition into a mold without using an adherend or a release film as described above. You can also do it.
Further, the present adhesive sheet can be made by directly filling the resin composition between the constituent members for an image display device which is an adherend.

<< This laminated sheet >>
A laminated sheet (referred to as "the present laminated sheet") as an example of the embodiment of the present invention is provided with a resin sheet or thin film glass on at least one side of the present adhesive sheet (see FIG. 6).

The resin sheet is a resin containing one or more kinds of resins selected from the group consisting of, for example, cycloolefin resin, triacetylcellulose resin, polymethylmethacrylate resin, epoxy resin, polyester resin and polyimide resin as the main component resin. You can raise the sheet.
At this time, the main component resin means the resin having the highest mass ratio among the resins constituting the resin sheet, and is 50% by mass or more, particularly 60% by mass or more of the resins constituting the resin sheet. It is a resin that accounts for 70% by mass or more, 80% by mass or more, 90% by mass or more, and 95% by mass or more (including 100% by mass).

Examples of the thin film glass include glass having bending resistance such as ultrathin plate glass (G-Leaf manufactured by Nippon Electric Glass Co., Ltd.).

<< Coating type polarizing element with this adhesive layer >>
A coated polarizing element with an adhesive layer (referred to as “the coated polarizing element with an adhesive layer”) as an example of the embodiment of the present invention is provided from the pressure-sensitive adhesive composition on at least one side of the coated polarizing element. It is a coating type polarizing element with a pressure-sensitive adhesive layer provided with the formed pressure-sensitive adhesive layer (referred to as “the main pressure-sensitive adhesive layer”) or the present pressure-sensitive adhesive sheet.

The coated polarizing element with the pressure-sensitive adhesive layer may be, for example, a pressure-sensitive adhesive sheet with a polarizing element provided with a coated polarizing element on at least one side of the pressure-sensitive adhesive sheet.
The pressure-sensitive adhesive sheet with a polarizing element can be used, for example, by forming a polarizing element on a base material having releasability and then transferring the polarizing element to the surface of the pressure-sensitive adhesive sheet, or directly on a coating type polarizing element. Can be produced by a method of molding, a method of forming a coating type polarizing element on the present adhesive sheet, or the like.

Further, the coating type polarizing element with the pressure-sensitive adhesive layer may be a polarizing element with a pressure-sensitive adhesive layer provided with the coating-type polarizing element on at least one side of the pressure-sensitive adhesive layer.
At this time, the present pressure-sensitive adhesive layer may be directly formed on the coating type polarizing element, or after forming the pressure-sensitive adhesive layer made of the present pressure-sensitive adhesive composition on another base material, the pressure-sensitive adhesive layer may be formed. May be transferred onto the coating type polarizing element.

Furthermore, even if the coating type polarizing element with the pressure-sensitive adhesive layer has a structure in which the coating type polarizing element and the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet are directly laminated, another member is sandwiched between the coating-type polarizing element. May be intervening. In either case, the effects of the present invention can be enjoyed.
At this time, the "other members" include, for example, a reflective sheet, a light guide plate and a light source, a diffusion film, a prism sheet, a liquid crystal panel, an organic EL panel, an antireflection film, a color filter, a polarizing plate, a retardation plate, and a glass substrate. , Cover glass, cover plastic, or a composite of two or more of these members.

<Coating type polarizing element>
As described above, the coating type polarizing element is a laminate containing a film formed by coating an optically anisotropic composition containing a liquid crystal compound. For example, an optically anisotropic composition containing a liquid crystal compound is applied onto an alignment film formed on a substrate to bring the optically anisotropic composition into an oriented state, and the optically anisotropic composition is cured in the oriented state to obtain an optically anisotropic composition. A sex layer can be formed. Then, various optically anisotropic members can be produced by using the optically anisotropic layer with a substrate or the optically anisotropic layer peeled from the substrate. The optically anisotropic member may have an optically anisotropic layer made of an optically anisotropic composition and an alignment film. Further, it may have only an optically anisotropic layer without an alignment film.
Examples of the liquid crystal compound include a polymerizable liquid crystal compound, a polymer liquid crystal compound, and a lyotropic liquid crystal compound.

Conventional polarizing plates generally have a structure in which a polyvinyl alcohol (PVA) film is sandwiched between protective films such as a TAC (triacetyl cellulose) film, and an adhesive is applied or an adhesive sheet is laminated. It was a target.
However, a polarizing plate using an optically anisotropic layer made of a coating type polarizing element can form a film by coating, so that the thickness can be reduced as compared with a conventional polarizing element.

Further, the conventional retardation plate is generally obtained by stretching a resin sheet such as polycarbonate, but if it is made too thin, the sheet is liable to break, so that there is a limit to thinning.
However, a retardation plate using an optically anisotropic layer made of a coating type polarizing element can be made thinner than a conventional stretched sheet, so that the thickness can be reduced.

By using a polarizing plate made of such a coating type polarizing element and / or a circular polarizing plate using a retardation plate in the image display device, it is possible to contribute to the thinning of the image display device.

The "base material" for forming the coating type polarizing element is, for example, a group consisting of a polyolefin resin, a cyclic polyolefin resin, a polyester resin, a poly (meth) acrylic acid ester resin, a cellulose ester resin, a polycarbonate resin, and a polyimide resin. Examples thereof include a resin sheet or glass containing one or more kinds of resins as main components selected from the above. The substrate may have other layers, such as an antistatic layer, a hardcoat layer, an anchor layer, a release layer, an easy-adhesion layer, a protective layer, a bleeding prevention layer, and a flattening layer, if necessary. ..

In order to orient the liquid crystal compound, a method using an orientation regulating force by an alignment film provided on the base material, an orientation regulating force by an external field such as an electric field or a magnetic field, and / or a shearing force at the time of coating can be mentioned. can. In particular, the method using an alignment film is preferable from the viewpoint that the polymerizable liquid crystal compound is in a highly ordered alignment state and a coated polarizing element exhibiting good optical performance can be obtained.

The alignment film provided on the substrate is a layer having an orientation regulating force for orienting the polymerizable liquid crystal compound described later in a desired direction. The alignment film has solvent resistance that does not dissolve when the optically anisotropic composition solution is applied, moderate solution affinity that does not repel the optically anisotropic composition solution, and heat resistance during heat treatment during solvent drying and liquid crystal alignment. Those having sex are preferable.
The alignment film may be subjected to an orientation treatment for controlling the orientation direction. At this time, as a method of alignment treatment, a known method (rubbing method, groove on the surface of the alignment film) described in pages 226 to 239 of "LCD Handbook" (Maruzen Co., Ltd., published on October 30, 2000). Examples thereof include a method of forming (fine groove structure), a method of using polarized ultraviolet light / polarized laser (photoalignment method), an orientation method by forming an LB film, an alignment method by oblique vapor deposition of an inorganic substance, and the like. In particular, the rubbing method and the photo-alignment method are preferable from the viewpoint of easily obtaining a high degree of orientation.
The thickness of the alignment film is usually 10 nm to 1000 nm, preferably 50 nm to 800 nm. Within the above range, it is possible to achieve both an orientation restricting force sufficient for orienting the polymerizable liquid crystal compound and a thin film.

In addition to the liquid crystal compound, the optically anisotropic composition includes a polymerization initiator, a polymerization inhibitor, a polymerization aid, a polymerizable non-liquid crystal compound, a surfactant, a leveling agent, a coupling agent, and a pH adjuster, if necessary. The composition may contain various additives and solvents such as a dispersant, an antioxidant, an organic / inorganic filler, and a metal oxide, and the cured product layer of the present composition exhibits an optical function as a polarizing element. ..

When the polarizing element is a polarizing film, it is preferable to include a dichroic dye in the optically anisotropic composition. Examples of the dichroic dye include iodine and a dichroic organic dye. The dichroic dye used may be one type or a plurality of different dyes may be combined.
The bicolor organic dye is not particularly limited, but is an azo dye, a quinone dye (including a naphthoquinone dye, an anthraquinone dye, etc.), a stilben dye, a cyanine dye, and a phthalocyanine dye. , Indigo dyes, condensed polycyclic dyes (including perylene dyes, oxazine dyes, acridine dyes, etc.) and the like can be mentioned. Among these dyes, azo dyes are preferable because they have a large molecular length-minor axis ratio and can exhibit good dichroism.

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable functional group, and has both properties as a polymerizable monomer and properties as a liquid crystal. Therefore, by cross-linking the polymerizable functional group in a state where the liquid crystal is oriented, the polymerizable functional group is crosslinked. The orientation can be fixed and optical anisotropy can be exhibited. The polymerizable liquid crystal compound used may be one kind, or a plurality of compounds having different structures may be combined.
As the polymerizable liquid crystal compound, either a low molecular weight liquid crystal compound having a polymerizable functional group or a high molecular weight liquid crystal compound having a polymerizable functional group may be used. Among them, a low molecular weight liquid crystal compound is preferable because the polymerizable liquid crystal compound tends to easily obtain a cured product showing high orientation.
As the liquid crystal phase represented by the polymerizable liquid crystal compound, a nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal, a discotic liquid crystal or the like can be appropriately selected. It is preferable to show a smectic liquid crystal.
The polymerizable functional group is preferably a photopolymerizable group because of the ease of fixing the oriented structure. Specifically, an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, an acryloylamino group, a methacryloylamino group, a vinyl group, a vinyloxy group, an ethynyl group, an ethynyloxy group, a 1,3-butadienyl group, 1,3. -Butadienyloxy group, oxylanyl group, oxetanyl group, glycidyl group, glycidyloxy group, styryl group, styryloxy group and the like can be mentioned. Of these, the (meth) acryloyl group is preferred.

As the polymerizable liquid crystal compound, a liquid crystal compound having a polymerizable group can be used without any particular limitation on the molecular structure. For example, examples of the polymerizable liquid crystal compound contained in the optically anisotropic composition include a compound represented by the following formula (1) (hereinafter, may be referred to as “polymerizable liquid crystal compound (1)”). Can be done.

Q ¹ -R ¹ -A ¹¹ -Y ¹ -A ^12- (Y ² -A ¹³ ) _k -R ² -Q ² ... (1)

(In equation (1),
-Q ¹ represents a hydrogen atom or a polymerizable group;
-Q ² represents a polymerizable group;
-R ^1- and -R ^2- each independently represent a chain organic group;
-A ^11- and -A ^13- each independently represent a partial structure represented by the following formula (2), a divalent organic group, or a single bond;
-A ^12- represents a partial structure or a divalent organic group represented by the following formula (2);
-Y ^1- and -Y ^2- are independently single-bonded, -C (= O) O-, -OC (= O)-, -C (= S) O-, and -OC (= S). -, -C (= O) S-, -SC (= O)-, -CH ₂ CH _2- , -CH = CH-, -C≡C-, -C (= O) NH-, -NHC ( = O)-, -CH ₂ O-, -OCH _2- , -CH ₂ S-, or -SCH _2- ;
One of -A ^11- and A ^13- is a partial structure represented by the following formula (2) or a divalent organic group;
k is 1 or 2.
When k is 2, the ^two −Y2 ^−A13− may be the same or different from each other. )

-Cy-X ² -C≡C-X ¹ -... (2)

(In equation (2),
-Cy- represents a hydrocarbon ring group or a heterocyclic group;
-X ^1- is -C (= O) O-, -OC (= O)-, -C (= S) O-, -OC (= S)-, -C (= O) S-,- SC (= O)-, -CH ₂ CH _2- , -CH = CH-, -C (= O) NH-, -NHC (= O)-, -CH ₂ O-, -OCH _2- , -CH Represents _2S- or _SCH2- ;
-X ^2- is a single bond, -C (= O) O-, -OC (= O)-, -C (= S) O-, -OC (= S)-, -C (= O) S -, -SC (= O)-, -CH ₂ CH _2- , -CH = CH-, -C (= O) NH-, -NHC (= O)-, -CH ₂ O-, -OCH _2- , -CH ₂ S-, or -SCH _2- . )

When —A ¹¹ − is a partial structure represented by the formula (2), the formula (1) may be the following formula (1A) or the following formula (1B).
Q ¹ -R ¹ -Cy-X ² -C≡C-X ¹ -Y ¹ -A ^12- (Y ² -A ¹³ ) _k -R ² -Q ² ... (1A)
Q ¹ -R ¹ -X ¹ -C≡C-X ² -Cy-Y ¹ -A ^12- (Y ² -A ¹³ ) _k -R ² -Q ² ... (1B)

Further, when —A ¹² − is a partial structure represented by the formula (2), the formula (1) may be the following formula (1C) or the following formula (1D).
Q ¹ -R ¹ -A ¹¹ -Y ¹ -Cy-X ² -C≡C-X ^1- (Y2-A ¹³ ) _k -R ^{2 -Q 2 ...} (1C)
Q ¹ -R ¹ -A ¹¹ -Y ¹ -X ¹ -C≡C-X ² -Cy- (Y ² -A ¹³ ) _k -R ² -Q ² ... (1D)

Further, when —A ¹³ − is a partial structure represented by the formula (2), the formula (1) may be the following formula (1E) or the following formula (1F).
Q ¹ -R ¹ -A ¹¹ -Y ¹ -A ^12- (Y ² -Cy-X ² -C≡C-X ¹ ) _k -R ² -Q ² ... (1E)
Q ¹ -R ¹ -A ¹¹ -Y ¹ -A ^12- (Y ² -X ¹ -C≡C-X ² -Cy) _k -R ² -Q ² ... (1F)

Similarly, when two or more of -A ^11- , -A ^12- , and -A ^13- are substructures represented by the formula (2), they are independently represented by the formula (2). The orientation of the partial structure may be reversed.

Further, as described above, -A ^11- , -A ^12- , and -A ^13- are each independently a partial structure or a divalent organic group represented by the formula (2), and in addition,-. A ^11- and -A ^13- may be single-bonded, but -A ^11- and -A ^13- are not both single-bonded.

As the polymerizable liquid crystal compound (1), the compound represented by the formulas (1A), (1B), (1E) or (1F) is preferable because it tends to obtain high orientation.

When the polymerizable liquid crystal compound is photopolymerized, it is preferable to include a photopolymerization initiator in the optically anisotropic composition. As the photopolymerization initiator, known ones can be appropriately used.

The thickness of the cured film of the optically anisotropic composition is preferably 100 nm or more, more preferably 300 nm or more, still more preferably 1 μm or more, from the viewpoint of ensuring the optical function.
On the other hand, the upper limit of the thickness is preferably 50 μm or less, more preferably 10 μm or less, still more preferably 5 μm or less, from the viewpoint of contributing to the thinning of the image display device.

On the cured film of the optically anisotropic composition, an overcoat layer, an antistatic layer, a hardcoat layer, an anchor layer, a release layer, an easy-adhesion layer, a protective layer, a bleeding prevention layer, a flattening layer, etc. are required. Other layers may be formed depending on the situation.

<< Adhesive sheet with this polarizing element >>
The pressure-sensitive adhesive sheet with a polarizing element (referred to as “the pressure-sensitive adhesive sheet with the current polarizing element”) as an example of the embodiment of the present invention has a configuration in which the pressure-sensitive adhesive sheet is provided on at least one side of the coated polarizing element, in other words. A coating type polarizing element is provided on at least one side of the pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive sheet with a polarizing element can be used, for example, by forming a polarizing element on a substrate having releasability and then transferring the polarizing element to the surface of the pressure-sensitive adhesive sheet, or directly on a coating type polarizing element. It can be obtained by a method of molding, a method of forming a coating type polarizing element after molding the present pressure-sensitive adhesive sheet, or the like.

Furthermore, even if the adhesive sheet with the present polarizing element has a structure in which the coating type polarizing element and the present adhesive sheet are directly laminated, there is a case where another member is interposed between the adhesive sheet. You may. In either case, the effects of the present invention can be enjoyed.
At this time, the "other member" includes, for example, the "other image display device component", for example, a reflective sheet, a light guide plate and a light source, a diffusion film, a prism sheet, a liquid crystal panel, an organic EL panel, and an antireflection film. , Color filters, polarizing plates, retardation plates, glass substrates, cover glasses, cover plastics, or those in which two or more of these members are compositely integrated.

The coating type polarizing element of the pressure-sensitive adhesive sheet with the present polarizing element is the same as the coating type polarizing element of the coating type polarizing element with the present pressure-sensitive adhesive layer.

<< This image display device >>
The image display device (referred to as "the present image display device") according to an example of the embodiment of the present invention is an image display device provided with the present adhesive layer.
The form of the pressure-sensitive adhesive layer is not limited, and the pressure-sensitive adhesive layer may be a sheet-shaped pressure-sensitive adhesive product previously molded into a sheet shape, that is, the present pressure-sensitive adhesive sheet.
As an example of the image display device, the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition, the coating type polarizing element, and, if necessary, another member, for example, another image display device component, may be combined. An image display device having a laminated structure can be mentioned.

In this image display device, as shown in FIG. 2 or FIG. 4, the coating type polarizing element and the present pressure-sensitive adhesive layer may have a structure in which they are directly laminated, or as shown in FIG. In addition, another member, for example, another image display device component may be interposed between the two. In either case, the effects of the present invention can be enjoyed.
At this time, the "other image display device components" are, for example, a reflective sheet, a light guide plate and a light source, a diffusion film, a prism sheet, a main laminate, a liquid crystal panel, an organic EL panel, an antireflection film, a color filter, and a polarizing plate. , A retardation plate, a glass substrate, a cover glass, a cover plastic, or a composite combination of two or more of these members.
In addition to the above members, other layers such as an antistatic layer, a hard coat layer, an anchor layer, a release layer, an easy-adhesion layer, a protective layer, a bleeding prevention layer, and a flattening layer are interposed as necessary. You may.

The pressure-sensitive adhesive layer in the image display device is preferably arranged on the visual side of the coating type polarizing element. Specifically, the present pressure-sensitive adhesive layer is preferably used for laminating a cover glass or a cover plastic. As a result, deterioration of the polarizing element due to incident light from the outside can be suppressed.

Specific examples of the image display device include a liquid crystal display, an organic EL display, an inorganic EL display, an electronic paper, a plasma display, a microelectromechanical system (MEMS) display, and the like.

The above-mentioned laminated sheet can also be used on the surface of the cover glass or the cover plastic of the image display device.

Further, the present pressure-sensitive adhesive layer has the above-mentioned light transmittance, b ^* value, gel fraction and thickness characteristics as in the present pressure-sensitive adhesive sheet, and enjoys a preferable range of each characteristic shown in the present pressure-sensitive adhesive sheet. be able to.

<Explanation of words>
When expressed as "X to Y" (X, Y are arbitrary numbers) in the present invention, unless otherwise specified, it means "X or more and Y or less" and "preferably larger than X" or "preferably more than Y". It also includes the meaning of "small".
Further, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), it means "preferably larger than X" or "preferably less than Y". Intention is also included.
Further, in the present invention, the "sheet" conceptually includes a sheet, a film, and a tape.

Hereinafter, it will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.

<Preparation of adhesive composition and adhesive sheet>
First, the details of the raw materials of the pressure-sensitive adhesive composition prepared in the examples will be described.

[(Meta) acrylic polymer (A)]
(Meta) acrylic polymer (A-1): 2-ethylhexyl acrylate: 67% by mass, methyl acrylate: 5% by mass, ethyl acrylate: 10% by mass, 2-hydroxyethyl acrylate: 14% by mass, 4-hydroxy Butyl acrylate: An acrylic acid ester copolymer polymer composed of 4% by mass, and the mass average molecular weight (Mw) of the acrylic acid ester copolymer polymer as measured by GPC was 700,000.
2-methacryloyloxyethyl 2-methacryloyloxyethyl with respect to 100 parts by mass of the copolymer obtained by copolymerizing (meth) acrylic polymer (A-2): butyl acrylate: 85% by mass and 2-hydroxyethyl acrylate: 15% by mass. It is an acrylic acid ester copolymer polymer in which a polymerizable carbon double bond group is introduced into the side chain by reacting 0.06 part by mass of isocyanate in an ethyl acetate solution, and the acrylic acid ester copolymer is measured by GPC. The mass average molecular weight (Mw) of the polymer was 900,000.

[Ultraviolet absorber (B)]
Ultraviolet absorber (B-1): 2,2'-dihydroxy-4-methoxybenzophenone (KEMIPRO B111, manufactured by Chemipro Kasei Co., Ltd.)
Ultraviolet absorber (B-2): 2,2', 4,4'-tetrahydroxybenzophenone (manufactured by Cipro Kasei Co., Ltd., SEESORB106)
-Ultraviolet absorber (B-3): 2- (5-chloro-2H-benzotriazole-2-yl) -4-methyl-6-tert-butylphenol (manufactured by BASF, Tinuvin 326)

[Radical Polymerization Initiator (C)]
Photocleavable radical polymerization initiator (C-1): 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO H, manufactured by IGM Resins).

[Polyfunctional (meth) acrylate (D)]
Polyfunctional (meth) acrylate (D-1): Polypropylene glycol # 700 diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., APG-700, molecular weight: 823)
Polyfunctional (meth) acrylate (D-2): Bifunctional urethane acrylate (manufactured by Mitsubishi Chemical Corporation, Shikou UV-3700B, molecular weight: 38000)

[others]
-Solvent: Ethyl acetate-silane coupling agent: 3-glycidoxypropylmethyldiethoxysilane (manufactured by Shinetsu Silicone, KBM403)
・ Rust inhibitor: 1,2,3-triazole

<Manufacturing of coated polarizing element>
The coating type polarizing element used for the evaluation, and the polymerizable liquid crystal compound and the dye contained in the coating type polarizing element will be described.

(Synthesis of polymerizable liquid crystal compound)
[Liquid crystal compound (I-1)]
The liquid crystal compound (I-1) represented by the following formula (I-1) was synthesized according to the description in JP-A-2020-042305.

(Dye synthesis)
[Dye (II-1)]
The dye (II-1) represented by the following formula (II-1) was synthesized according to the synthetic method described below.

Synthesis of (II-1-a):
Tetrahydrofuran (100 mL) and sodium hydride (purity 60%, 6.7 g, 168.0 mmol) were added to the ice-cooled reactor, and diethyl (4-nitrobenzyl) phosphonate (18.0 g, 65.9 mmol) was added. A mixture of 4-butylbenzaldehyde (9.1 g, 56.1 mmol) and tetrahydrofuran (50 mL) was added dropwise over 10 minutes, washed with tetrahydrofuran (30 mL), and then stirred at 50 ° C. for 0.5 hour. The reaction solution was poured into water, extracted with ethyl acetate, washed with water and saturated brine, and the solvent was distilled off. The obtained crude product was dissolved by heating in ethyl acetate (20 mL), cooled by adding hexane (50 mL), the precipitated precipitate was filtered off, washed with hexane, and dried under reduced pressure (II-1-). 15.0 g of a) was obtained.

Synthesis of (II-1-b):
(II-1-a) (15.0 g, 53.3 mmol), tetrahydrofuran (150 mL), iron powder (13.9 g, 248.9 mmol) were mixed and dissolved in water (30 mL) ammonium chloride (13.3 g). , 248.6 mmol) was added dropwise, and the mixture was stirred at 50 ° C. for 3 hours. The mixture was filtered through cerite, extracted with ethyl acetate, washed with water and saturated brine, and the solvent was distilled off. The obtained crude product was suspended in hexane, the precipitate was filtered off, washed with hexane, and dried to obtain 10.9 g of (II-1-b).

Synthesis of (II-1):
(II-1-b) (2.51 g, 10.0 mmol), N-methylpyrrolidone (40 mL), concentrated hydrochloric acid (2.2 mL), water (20 mL) are mixed, cooled to 3 ° C, and then sodium nitrite. (789 mg, 11.4 mmol) was added, and the mixture was stirred at 15 ° C. for 3.5 hours.
1-Phenylpyrrolidine (1.47 g, 10.0 mmol), methanol (60 mL) and water (30 mL) were mixed and the pH was adjusted to 3.5 with concentrated hydrochloric acid. The solution containing the above diazonium salt was added dropwise while maintaining the pH at 3 to 5 by adding an aqueous sodium hydroxide solution, and then the mixture was stirred at 15 ° C. for 3 hours.
The resulting precipitate was filtered, washed with water and dried under reduced pressure. The obtained crude product was purified by silica gel column chromatography (hexane / methylene chloride) to obtain 3.06 g of a red solid dye (II-1).

[Dye (II-2)]
The dye (II-2) represented by the following formula (II-2) was synthesized according to the synthesis method described below.

Synthesis of (II-2):
(II-1-b) (1.0 g, 4.0 mmol) and N-methylpyrrolidone (13 mL) are mixed, concentrated hydrochloric acid (1,0 g, 10.0 mmol) is added, and the mixture is cooled in an ice bath and then water. Sodium nitrite (0.3 g, 4.4 mmol) dissolved in (1.3 mL) was added, and the mixture was stirred for 1 hour. The reaction solution was coupled with 1-phenylpiperidine (0.6 g, 4.0 mnmol) dissolved in methanol (25 mL) and water (6.5 mL) at pH = 7, and then the precipitate was filtered off with water. It was washed and dried under reduced pressure. The obtained crude product was purified by silica gel column chromatography (hexane / methylene chloride) to obtain 760 mg of a dye (II-2) which is an orange solid.

The chemical structures of the liquid crystal compounds and dyes synthesized above are shown below. In the formula, C ₁₁ H ₂₂ means that 11 methylene chains are linearly bonded.

The chemical structures of the dye (II-3) and the dye (II-4) used in Examples and Comparative Examples are shown below.

(Preparation of optically anisotropic composition)
In 69.31 parts of cyclopentanone, 28.57 parts of liquid crystal compound (I-1), 0.10 part of dye (II-1), 0.43 part of dye (II-2), dye (II). -3) 0.39 part of (Made by Hayashihara Co., Ltd.), 0.90 part of dye (II-4) (manufactured by Showa Kako Co., Ltd.), 0.23 part of the following initiator (PI-1), BYK- Add 0.34 part of 361N (BYK-Chemie), heat and stir at 80 ° C., and then filter using a syringe equipped with a syringe filter (Membrane Solutions, PTFE13045, caliber 0.45 μm) to obtain optics. An anisotropic composition was obtained.

(Manufacturing of coated polarizing element)
The optically anisotropic composition prepared above is formed into a film by a spin coat method on a substrate on which a polyimide alignment film (LX1400, manufactured by Hitachi Chemical DuPont Microsystems, the alignment film is formed by a rubbing method) is formed on glass. Then, after heating and drying at 120 ° C. for 2 minutes, the mixture was cooled to a liquid crystal phase and polymerized at an exposure amount of 500 mj / cm ² (365 nm standard) to obtain a coated polarizing element having a thickness of about 3 μm.

Further, by the method described below, an overcoat layer was further provided on the coating type polarizing element by using an overcoat composition.

The curable (meth) acryloyl copolymer (R-1) contained in the overcoat composition was synthesized by the following method.
In a flask equipped with a thermometer, a stirrer and a reflux cooling tube, propylene glycol monomethyl ether (157 parts by mass), glycidyl methacrylate (98 parts by mass), methyl methacrylate (1.0 part by mass), ethyl acrylate (1.0 part by mass). ), And 2,2'-azobis (2,4-dimethylvaleronitrile) (1.0 part by mass), γ-trimethoxysilylpropanethiol (KBM-803 manufactured by Shin-Etsu Chemical Industry Co., Ltd.) by 1.9 parts by mass. In addition, the reaction was carried out at 65 ° C. for 3 hours.
Then, 2,2'-azobis (2,4-dimethylvaleronitrile) (0.5 parts by mass) was further added and reacted for 3 hours, and then propylene glycol monomethyl ether (138 parts by mass) and p-methoxyphenol (13 parts by mass) were added. 0.45 parts by mass) was added and heated to 100 ° C.
Next, acrylic acid (51 parts by mass) and triphenylphosphine (3.1 parts by mass) were added and reacted at 110 ° C. for 6 hours to obtain a carbon-carbon double bond amount (acryloyl equivalent (acryloyl group)). (Introduction amount)) 4.6 mmol / g (meth) acryloyl copolymer (R-1) was obtained. The mass average molecular weight (Mw) was 17,700.

23.08 parts of a 65% solution of propylene glycol monomethyl ether of the curable (meth) acryloyl copolymer (R-1), 0.13 parts of the following photopolymerization initiator (PI-2), BYK-3550 (BYK). -0.40 part of (Chemie) and 76.39 parts of ethanol were mixed and stirred to obtain an overcoat composition.
This overcoat composition was formed into a film on the coating type polarizing element by a spin coating method, dried by heating at 50 ° C. for 2 minutes, polymerized at an exposure amount of 500 mj / cm ² (365 nm standard), and then polymerized. The mixture was heated at 80 ° C. for 5 minutes, and an overcoat layer having a thickness of about 5 μm was laminated to obtain a coating type polarizing element with an overcoat layer.
When the obtained coating type polarizing element with an overcoat layer was held over a commercially available polarizing plate and rotated, it became bright and dark, and it was confirmed that it showed good performance that could be used as a polarizing film.

[Example 1]
200 parts by mass of (meth) acrylic polymer (A-1) solution (diluting solvent: ethyl acetate solid content concentration: 50% by mass), 6 parts by mass of ultraviolet absorber (B-1), photocleavable radical polymerization 3 parts by mass of the initiator (C-1), 25 parts by mass of the polyfunctional (meth) acrylate initiator (D-1), 3-glycidoxypropylmethyldiethoxysilane (manufactured by Shinetsu Silicone) which is a silane coupling agent. , KBM403) by 0.3 parts by mass, the rust preventive agent 1,2,3-triazole by 0.3 parts by mass and ethyl acetate by 101 parts by mass, to prepare a pressure-sensitive adhesive composition 1.
The pressure-sensitive adhesive composition 1 after solvent drying was developed into a sheet on a release film (diafoil MRV manufactured by Mitsubishi Chemical Corporation) having a thickness of 100 μm that had been subjected to silicone release treatment so that the thickness of the pressure-sensitive adhesive composition 1 was 50 μm.

Next, the sheet-shaped pressure-sensitive adhesive composition 1 together with the release film was placed in a dryer heated to 95 ° C. and held for 10 minutes to volatilize the solvent contained in the pressure-sensitive adhesive composition 1.
Further, the mold release film (diafoil MRQ manufactured by Mitsubishi Chemical Co., Ltd.) having a thickness of 75 μm, which has been subjected to a silicone mold release treatment, is laminated on the sheet-shaped pressure-sensitive adhesive composition 1 obtained by drying the solvent to form a laminate. The integrated irradiation amount at a wavelength of 365 nm was 1000 mJ / cm ² and the integrated irradiation amount at a wavelength of 405 nm was 1400 mJ / cm ² with respect to the pressure-sensitive adhesive composition 1 through the release film using a high-pressure mercury lamp. Light irradiation was carried out so as to obtain an adhesive sheet 1 with a release film (adhesive sheet thickness: 50 μm) in which release films were laminated on both the front and back sides.

[Examples 2 to 4, Comparative Examples 1 to 2]
Table 1 shows the types and amounts of the (meth) acrylic polymer (A), ultraviolet absorber (B), radical polymerization initiator (C), polyfunctional (meth) acrylate (D) and other additives used. Except for the contents shown, the pressure-sensitive adhesive compositions 2 to 6 and the pressure-sensitive adhesive sheets 2 to 6 with a release film were prepared in the same manner as in Example 1.

<Evaluation>
The pressure-sensitive adhesive compositions and pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were measured and evaluated as follows.

[Light transmittance]
The release films on both sides of the adhesive sheet with the release film produced in Examples and Comparative Examples are sequentially peeled off, and the adhesive sheet (thickness 50 μm) is attached so as to be sandwiched between two soda lime glasses (thickness 0.5 mm). Then, an autoclave treatment (60 ° C., gauge pressure 0.2 MPa, 20 minutes) was applied, and the film was finished and adhered to prepare a sample for evaluating optical characteristics.
The light transmittance of the prepared sample for optical characteristic evaluation in the wavelength range of 360 to 430 nm was measured with a spectrophotometer (manufactured by Shimadzu Corporation; device name "UV2450").

[B ^* value]
The b ^* value of the prepared optical characteristic evaluation sample is set to JIS.
It was measured with a spectrocolorimeter (manufactured by Suga Test Instruments Co., Ltd., device name "SC-P") in accordance with Z8781-4.

[Gel fraction]
The gel fraction of the pressure-sensitive adhesive composition prepared in the middle of Examples and Comparative Examples was measured by the following procedure.
1) The pressure-sensitive adhesive composition is weighed (W1) and wrapped in a pre-weighted SUS mesh (W0).
2) Immerse the SUS mesh in 100 mL of ethyl acetate for 24 hours.
3) Take out the SUS mesh and dry it at 75 ° C. for 4 and a half hours.
4) Obtain the mass (W2) after drying, and measure the gel fraction of the pressure-sensitive adhesive composition from the following formula.
Gel fraction (%) = 100 × (W2-W0) / W1

[Adhesive force]
For the adhesive sheet with a release film produced in Examples and Comparative Examples, one of the release films was peeled off, and a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd .; trade name "Cosmo Shine A4300", thickness 100 μm) was used as a backing film. The roll was crimped with a roller. This was cut into strips having a width of 10 mm and a length of 100 mm, the remaining release film was peeled off, and the exposed adhesive surface was rolled and attached to soda lime glass using a hand roller. An autoclave treatment (60 ° C., gauge pressure 0.2 MPa, 20 minutes) was applied to finish and paste, and an adhesive strength measurement sample was prepared.
Using a universal material testing machine (manufactured by INSTRON, device name "5965 type"), peel the adhesive sheet from the glass while pulling the backing film at an angle of 180 ° at a peeling speed of 60 mm / min, and pull it with a load cell. The strength was measured, and the 180 ° peel strength (N / cm) of the adhesive sheet with respect to the glass was measured and shown as "adhesive strength" in Table 1.

[Protective function of coated polarizing element]
With respect to the adhesive sheet with a release film produced in Examples and Comparative Examples, one of the release films is peeled off, the adhesive sheet is roll-bonded onto the overcoat layer of the coating type polarizing element with a hand roller, and the remaining release is performed. The adhesive surface exposed by peeling off the film was rolled and attached to soda lime glass using a hand roller. An autoclave treatment (60 ° C., gauge pressure 0.2 MPa, 20 minutes) was applied, and the finish was attached to prepare a sample for measuring the protective function of the coating type polarizing element.
The sample was subjected to a light resistance test for 40 hours under an ultraviolet irradiation condition of illuminance: 0.55 W / cm ² (340 nm) using a xenon light resistance tester (manufactured by Atlas, device name "Ci4000"). ..
As the results of the light resistance test, Table 1 shows the values of the change in the degree of polarization (polarity before the test-polarity after the test) at a wavelength of 595 nm before and after the light resistance test.

The degree of polarization (Pe) is the "transmittance of the anisotropic dye film with respect to the polarization in the absorption axis direction" and the "polarization axis direction of the anisotropic dye film" by incidenting the measurement light of linear polarization on the anisotropic dye film. "Transmittance with respect to polarization" was measured using a spectrophotometer equipped with a Gran Thomson spectrometer (manufactured by Otsuka Electronics Co., Ltd., product name "RETS-100"), and calculated by the following equation.
Pe = (Ty-Tz) / (Ty + Tz)
(During the ceremony,
Tz is the transmittance of the anisotropic dye film for polarization in the absorption axis direction;
Ty is the transmittance of the anisotropic dye film with respect to the polarization in the polarization axis direction. )

It was evaluated according to the following criteria.
○ (good): The amount of change in the degree of polarization before and after the light resistance test is a value of 0.25 or less.
× (poor): The amount of change in the degree of polarization before and after the light resistance test is a value larger than 0.25.

The results obtained by measurement and evaluation are shown in Table 1.

From the above examples and the test results conducted by the present inventor so far, in order to prevent the polarization performance of the coated polarizing element from deteriorating with time due to exposure, at least from the transmittance at a wavelength of 400 nm in Comparative Example 1. It turns out that it also needs to be low.

Based on the above examples and the test results conducted by the present inventor so far, the pressure-sensitive adhesive composition containing the (meth) acrylic polymer (A) and the ultraviolet absorber (B) is formed from the pressure-sensitive adhesive composition. If the transmittance of the pressure-sensitive adhesive layer at a wavelength of 400 nm is 50% or less, the coating-type polarizing element can be used in combination with the coating-type polarizing element to prevent the polarization performance of the coating-type polarizing element from deteriorating over time due to exposure. I found that I could do it.

1 Adhesive sheet for coating type polarizing element of the present invention
2 Cover glass or cover plastic
3 Coating type polarizing element (polarizing layer)
4 Orientation film
5 Coating type polarizing element (phase difference layer)
6 Polarizing plate
7 Phase difference plate
8 LCD panel
9 Organic EL panel
10 Resin sheet or glass
11a, 11b Release film
12a-12c Adhesive layer or adhesive layer

Claims (20)

A pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A), an ultraviolet absorber (B) and a radical polymerization initiator (C), at a wavelength of 400 nm of a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. A pressure-sensitive adhesive composition for a coated polarizing element having a transmittance of 50% or less. The pressure-sensitive adhesive composition for a coating type polarizing device according to claim 1, further comprising a polyfunctional (meth) acrylate (D). The coated polarizing element according to claim 1 or 2, wherein the content of the ultraviolet absorber (B) is 0.1 part by mass or more with respect to 100 parts by mass of the (meth) acrylic polymer (A). Adhesive composition for. The pressure-sensitive adhesive composition for a coated polarizing element according to any one of claims 1 to 3, wherein the ultraviolet absorber (B) contains a benzophenone structure. The pressure-sensitive adhesive composition for a coated polarizing device according to any one of claims 1 to 4, wherein the polyfunctional (meth) acrylate (D) is a (meth) acrylate oligomer having a molecular weight of 3000 or more. The pressure-sensitive adhesive composition for a coated polarizing element according to any one of claims 1 to 5, wherein the (meth) acrylic polymer (A) has a polymerizable carbon double bond group in the side chain. The pressure-sensitive adhesive composition for a coated polarizing element according to any one of claims 1 to 6, wherein the radical polymerization initiator (C) is a photocleavable radical polymerization initiator. The pressure-sensitive adhesive composition for a coated polarizing device according to any one of claims 1 to 7, which can be cured in multiple stages. A pressure-sensitive adhesive sheet for a coating-type polarizing element, which comprises a pressure-sensitive adhesive layer formed by using the pressure-sensitive adhesive composition for a coating-type polarizing element according to any one of claims 1 to 8. b ^* The pressure-sensitive adhesive sheet for a coating type polarizing element according to claim 9, wherein the value is 10 or less. The pressure-sensitive adhesive sheet for a coating type polarizing element according to claim 9 or 10, wherein the gel fraction is 20% or more and 95% or less. The pressure-sensitive adhesive sheet for a coating type polarizing element according to any one of claims 9 to 11, wherein the thickness is 10 μm or more and 175 μm or less. A pressure-sensitive adhesive sheet with a release film, which comprises a structure in which the pressure-sensitive adhesive sheet for a coating type polarizing element according to any one of claims 9 to 12 and a release film are laminated. The pressure-sensitive adhesive sheet for a coated polarizing element according to any one of claims 9 to 12 comprises a cycloolefin resin, a triacetylcellulose resin, a polymethylmethacrylate resin, an epoxy resin, a polyester resin and a polyimide resin on at least one side thereof. A resin sheet containing one or more kinds of resins selected from the group as a main component resin, or a laminated sheet provided with thin film glass. A coated polarizing element with an adhesive layer provided with an adhesive layer formed from the adhesive composition for a coated polarizing element according to any one of claims 1 to 8 on at least one side of the coated polarizing element. .. An adhesive sheet with a polarizing element provided with a coating type polarizing element on at least one side of the adhesive sheet according to any one of claims 9 to 12. An image display device having a structure in which a coating type polarizing element and an adhesive layer are laminated directly or via other members.
The pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A), an ultraviolet absorber (B) and a radical polymerization initiator (C), and has a transmittance of 50 at a wavelength of 400 nm. % Or less, image display device. The image display device according to claim 17, wherein the pressure-sensitive adhesive layer has a transmittance of less than 20% at a wavelength of 380 nm. The image display device according to claim 17, wherein the pressure-sensitive adhesive layer has a transmittance of 50% or more at a wavelength of 430 nm. 17. The pressure-sensitive adhesive layer has a light transmittance T (380) at a wavelength of 380 nm, a light transmittance T (430) at a wavelength of 430 nm, and a b ^* value satisfying the relationship of the following formulas (I) and (II). The image display device according to any one of 19 to 19.
0 ≤ T (380) x b ^* ≤ 50 (I)
70 ≤ T (430) x b ^* ≤ 220 (II)

Images