Adhesive agent composition, adhesive sheet, optical layered body, and image display device

Abstract

To provide a photocurable adhesive agent composition for creating an adhesive sheet suitable for use in a high-temperature environment.SOLUTION: The photocurable adhesive agent composition provided herein comprises at least one selected from the group consisting of monomers and partial polymers of these monomers. The monomers include nitrogen atom-containing monomers. The adhesive agent composition contains a radical scavenger.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an adhesive composition, an adhesive sheet, an optical laminate, and an image display device.

Background Art

[0002] Various image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices generally include an optical laminate including an optical film such as a polarizing film and an adhesive sheet. An adhesive sheet is usually used for bonding between optical films included in the optical laminate and for bonding between the optical laminate and the image display panel. Patent Document 1 discloses a photocurable adhesive sheet for attaching polarizing films to each other. The photocurable adhesive sheet is formed from a photocurable composition.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a photocurable adhesive sheet formed from a photocurable composition is used, for example, in a high-temperature environment of 100° C. or higher, there is a tendency for problems to occur in the quality of the image of the image display device.

[0005] An object of the present invention is to provide a photocurable adhesive composition for producing an adhesive sheet suitable for use in a high-temperature environment.

Means for Solving the Problems

[0006] The present invention is a photocurable adhesive composition containing at least one selected from the group consisting of a monomer group and a partial polymer of the monomer group, the monomer group includes a nitrogen atom-containing monomer, a photocurable pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition including a radical scavenger; to provide.

[0007] Furthermore, the present invention provides There is also provided a pressure-sensitive adhesive sheet formed from the above photocurable pressure-sensitive adhesive composition.

[0008] Furthermore, the present invention provides An optical laminate is provided, comprising the pressure-sensitive adhesive sheet and an optical film.

[0009] Furthermore, the present invention provides An image display device including the above optical laminate is provided. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a photocurable pressure-sensitive adhesive composition for producing a pressure-sensitive adhesive sheet suitable for use in high-temperature environments. [Brief explanation of the drawings]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0012] The photocurable pressure-sensitive adhesive composition according to the first aspect of the present invention is a photocurable pressure-sensitive adhesive composition containing at least one selected from the group consisting of a monomer group and a partial polymer of the monomer group, wherein the monomer group includes a nitrogen atom-containing monomer, and the pressure-sensitive adhesive composition contains a radical scavenger.

[0013] In the second aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to the first aspect, the radical scavenger has a polymerizable unsaturated double bond and corresponds to a part of the monomers constituting the monomer group.

[0014] In the third aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to the first aspect, the radical scavenger does not have a polymerizable unsaturated double bond.

[0015] In the fourth aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to any one of the first to third aspects, the radical scavenger includes at least one selected from the group consisting of a phenoxy-based radical scavenger, an amine-based radical scavenger, and a phosphite-based radical scavenger.

[0016] In the fifth aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to the fourth aspect, the radical scavenger includes at least one of a phenoxy-based radical scavenger and a phosphite-based radical scavenger.

[0017] In the sixth aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to the fifth aspect, the radical scavenger has a phenoxy structure.

[0018] In the seventh aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to any one of the first to sixth aspects, the content of the solvent in the pressure-sensitive adhesive composition is 5% by weight or less.

[0019] In the eighth aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to the second aspect, the content of the radical scavenger in the pressure-sensitive adhesive composition is 30 parts by weight or less per 100 parts by weight of the monomer group.

[0020] In the ninth aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to the third aspect, the content of the radical scavenger in the pressure-sensitive adhesive composition is 5 parts by weight or less with respect to 100 parts by weight of the monomer group.

[0021] In the tenth aspect of the present invention, for example, in the photocurable pressure-sensitive adhesive composition according to any one of the first to ninth aspects, the monomer group includes (meth)acrylic monomers.

[0022] The pressure-sensitive adhesive sheet according to the eleventh aspect of the present invention is formed from the photocurable pressure-sensitive adhesive composition according to any one of the first to tenth aspects.

[0023] In the twelfth aspect of the present invention, for example, in the pressure-sensitive adhesive sheet according to the eleventh aspect, in a test of leaving the pressure-sensitive adhesive sheet in an environment of 105°C for 24 hours, the absolute value |Ga - Gb| of the difference between the gel fraction Ga before the test and the gel fraction Gb after the test is 10% or less.

[0024] The optical laminate according to the thirteenth aspect of the present invention includes the pressure-sensitive adhesive sheet according to the eleventh or twelfth aspect and an optical film.

[0025] The image display device according to the fourteenth aspect of the present invention includes the optical laminate according to the thirteenth aspect.

[0026] The present invention will be described in detail below. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[0027] [Pressure-sensitive Adhesive Composition] The pressure-sensitive adhesive composition of this embodiment is a photocurable pressure-sensitive adhesive composition (in other words, a photocurable composition; hereinafter, also simply referred to as "pressure-sensitive adhesive composition"), and includes at least one selected from the group consisting of a monomer group and a partial polymer of the monomer group. The monomer group includes a nitrogen atom-containing monomer. The pressure-sensitive adhesive composition includes a radical scavenger.

[0028] In an image display device using a pressure-sensitive adhesive sheet formed from a photocurable pressure-sensitive adhesive composition, the deterioration of image quality due to exposure to a high-temperature environment may be caused by the fact that in the optical laminate, the pressure-sensitive adhesive sheet and the adherend (object to be adhered) in contact with it are likely to peel off at high temperatures. In addition, the above-mentioned deterioration of image quality may also be caused by the foaming of the monomers remaining in the pressure-sensitive adhesive sheet at high temperatures. According to the studies of the present inventors, in a pressure-sensitive adhesive sheet formed from a photocurable pressure-sensitive adhesive composition containing a nitrogen atom-containing monomer, for example, at a high temperature of 80°C or higher, the above-mentioned peeling or foaming tends to be suppressed. In the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition, with the addition of the nitrogen atom-containing monomer, the polymerization rate was improved, and the molecular weight of the polymer tended to increase. It is presumed that by improving the polymerization rate and increasing the molecular weight of the polymer in this way, the durability of the pressure-sensitive adhesive sheet at high temperatures is improved.

[0029] In addition, according to the studies of the present inventors, in a pressure-sensitive adhesive sheet formed from a photocurable pressure-sensitive adhesive composition containing a radical scavenger in addition to the nitrogen atom-containing monomer, for example, even at a further high temperature of 100°C or higher, the above-mentioned peeling or foaming tends to be suppressed. In the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition, in addition to the nitrogen atom-containing monomer, with the further addition of the radical scavenger, for example, at a further high temperature of 100°C or higher, it is considered that the decrease in the gel fraction of the cross-linked polymer in the pressure-sensitive adhesive sheet is suppressed. It is presumed that by suppressing the decrease in the gel fraction of the pressure-sensitive adhesive sheet in this way, the durability of the pressure-sensitive adhesive sheet at a further high temperature is improved.

[0030] <Monomer group> As described above, the pressure-sensitive adhesive composition contains a monomer group. The monomer group contains, for example, (meth)acrylic monomers. The content of the (meth)acrylic component in the pressure-sensitive adhesive composition, that is, the (meth)acrylic monomer and its partial polymer, may be 50% by weight or more, 60% by weight or more, 70% by weight or more, or even 80% by weight or more. In this case, an acrylic pressure-sensitive adhesive sheet mainly composed of a (meth)acrylic polymer can be formed. In other words, the polymer may be a (meth)acrylic polymer. However, as long as it contains a nitrogen atom-containing monomer, the pressure-sensitive adhesive composition is not limited to the above example. In this specification, (meth)acrylic means acrylic and methacrylic. (Meth)acrylate means acrylate and methacrylate. In this specification, the main component means the component with the largest content. The content of the main component may be, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, or even 80% by weight or more.

[0031] Examples of the (meth)acrylic monomer are alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms in the side chain. The number of carbon atoms of the alkyl group may be 7 or less, 6 or less, 5 or less, or even 4 or less. The alkyl group may be linear or branched. Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate (lauryl (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, and octadecyl (meth)acrylate. The alkyl (meth)acrylate may be n-butyl (meth)acrylate.

[0032] The content of the alkyl (meth)acrylate in the monomer group is, for example, 40% by weight or more, and may be 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or even 95% by weight or more. In calculating the content, the weight of the partial polymer is converted to the weight as each monomer before polymerization.

[0033] The monomer group may contain a carboxyl group-containing monomer. In this case, the polymer further has a structural unit derived from the carboxyl group-containing monomer. The carboxyl group-containing monomer, when present together with the nitrogen atom-containing monomer, contributes to the improvement of the viscosity of the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition. The carboxyl group-containing monomer may be a (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain the carboxyl group-containing monomer. Examples of the carboxyl group-containing monomer are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. The content of the carboxyl group-containing monomer in the monomer group is, for example, 10% by weight or less, 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, 5.5% by weight or less, and further may be 5% by weight or less. The lower limit of the content is, for example, 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 1.5% by weight or more, 2% by weight or more, 2.5% by weight or more, 3% by weight or more, 3.5% by weight or more, 4% by weight or more, and further may be 4.5% by weight or more. The monomer group may not contain a carboxyl group-containing monomer.

[0034] The monomer group may contain a hydroxy group-containing monomer. In this case, the polymer further has a structural unit derived from the hydroxy group-containing monomer. The hydroxy group-containing monomer may be a (meth)acrylic monomer. In other words, the (meth)acrylic monomer may contain a hydroxy group-containing monomer. Examples of the hydroxy group-containing monomer are 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. The hydroxy group-containing monomer is preferably 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate. The content rate of the hydroxy group-containing monomer in the monomer group is, for example, 10% by weight or less, and may be 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, 0.8% by weight or less, 0.5% by weight or less, 0.3% by weight or less, 0.2% by weight or less, and even 0.1% by weight or less. The lower limit of the content rate may be, for example, 0.01% by weight or more, 0.03% by weight or more, and even 0.05% by weight or more. The monomer group may not contain a hydroxy group-containing monomer.

[0035] The monomer group may contain a benzyl group-containing monomer. In this case, the polymer further has a structural unit derived from the benzyl group-containing monomer. The benzyl group-containing monomer may be a (meth)acrylic monomer. In other words, the (meth)acrylic monomer may contain a benzyl group-containing monomer. Examples of the benzyl group-containing monomer are benzyl (meth)acrylate and methoxybenzyl (meth)acrylate. The content rate of the benzyl group-containing monomer in the monomer group is, for example, 30% by weight or less, and may be 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, and even 5% by weight or less. The lower limit of the content rate may be, for example, 1% by weight or more, 2% by weight or more, and even 3% by weight or more. The monomer group may not contain a benzyl group-containing monomer.

[0036] The monomer group contains a nitrogen atom-containing monomer as described above. The nitrogen atom-containing monomer means a monomer having at least one nitrogen atom in the molecule (within one molecule).

[0037] As the nitrogen atom-containing monomer, N-vinyl cyclic amide, (meth)acrylamide, etc. are preferable. The nitrogen atom-containing monomer may be used alone or in combination of two or more kinds.

[0038] The N-vinyl cyclic amide is preferably represented by the following formula (A).

Chemical formula

[0039] In formula (A), R 1 is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, more preferably a divalent saturated hydrocarbon group (for example, an alkylene group having 3 to 5 carbon atoms). Note that formula (A) represents that N and R 1 are directly bonded by a single bond to form a ring structure.

[0040] Examples of the N-vinyl cyclic amide represented by formula (A) include N-vinyl-2-pyrrolidone (NVP), N-vinyl-2-piperidone, N-vinyl-2-caprolactam, N-vinyl-3-morpholinone, N-vinyl-1,3-oxazine-2-one, N-vinyl-3,5-morpholinedione, etc. are preferable, more preferably N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam, and even more preferably N-vinyl-2-pyrrolidone.

[0041] Examples of (meth)acrylamide include (meth)acrylamide, N-alkyl(meth)acrylamide, and N,N-dialkyl(meth)acrylamide. Examples of N-alkyl(meth)acrylamide include N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-n-butyl(meth)acrylamide, and N-octyl acrylamide. N-alkyl(meth)acrylamide also includes (meth)acrylamide having an amino group such as dimethylaminoethyl(meth)acrylamide, diethylaminoethyl(meth)acrylamide, and dimethylaminopropyl(meth)acrylamide.

[0042] Examples of N,N-dialkyl(meth)acrylamide include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide.

[0043] (meth)acrylamide also includes various N-hydroxyalkyl(meth)acrylamide. Examples of N-hydroxyalkyl(meth)acrylamide include N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, and N-methyl-N-2-hydroxyethyl(meth)acrylamide.

[0044] (Meth)acrylamide includes, for example, various N-alkoxyalkyl (meth)acrylamides. Examples of N-alkoxyalkyl (meth)acrylamides include N-methoxymethyl (meth)acrylamide and N-butoxymethyl (meth)acrylamide.

[0045] Examples of N-vinyl cyclic amides and nitrogen atom-containing monomers other than (meth)acrylamide include amino group-containing monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; heterocyclic ring-containing monomers such as (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloylpyrrolidine, (meth)acryloylpiperidine, and N-methylvinylpyrrolidone; maleimide-based monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide, itaconimide-based monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-laurylitaconimide, and N-cyclohexylitaconimide, imide group-containing monomers of succinimide-based monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; and isocyanate group-containing monomers such as 2-(meth)acryloyloxyethyl isocyanate.

[0046] The content rate of the nitrogen atom-containing monomer in the monomer group is, for example, 30% by weight or less, and may be 25% by weight or less, 20% by weight or less, 18% by weight or less, 15% by weight or less, 13% by weight or less, 12% by weight or less, 11% by weight or less, and further may be 10% by weight or less. The lower limit of the content rate may be, for example, 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 2% by weight or more, and further may be 3% by weight or more.

[0047] In the pressure-sensitive adhesive composition, each of the above-described monomer groups may be contained as a partial polymer. The partial polymer may be either a homopolymer or a copolymer. The pressure-sensitive adhesive composition may not contain a partial polymer.

[0048] <Photoinitiator> As described above, since the pressure-sensitive adhesive composition is a photocurable composition, it usually contains a photoinitiator. Examples of the photoinitiator are photo radical generators that generate radicals upon irradiation with light. In the photoinitiator, the extinction coefficient with respect to light having a wavelength of 340 nm is, for example, 0.1 L / (g·cm) or more, and may be 0.5 L / (g·cm) or more, 1.0 L / (g·cm) or more, 3.0 L / (g·cm) or more, and further may be 5.0 L / (g·cm) or more. The upper limit of this extinction coefficient is not particularly limited, and is, for example, 50 L / (g·cm) or less. The extinction coefficient of the photoinitiator is a calculated value from the absorbance of a 0.01 mg / mL methanol solution measured with a visible-ultraviolet spectrophotometer using a quartz cell with an optical path length of 1 cm.

[0049] Examples of photoinitiators include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzyl dimethyl ketal; substituted benzoin ethers such as anisole methyl ether; substituted acetophenones such as 2,2 - diethoxyacetophenone and 2,2 - dimethoxy - 2 - phenylacetophenone; α - hydroxyalkylphenones such as 1 - hydroxycyclohexyl - phenyl ketone, 2 - hydroxy - 2 - methylpropiophenone, 2 - hydroxy - 4’-(2 - hydroxyethoxy)-2 - methylpropiophenone, and 2,2’ - dihydroxy - 2,2’ - dimethyl - 1,1’ - [methylenebis(4,1 - phenylene)] bis(propan - 1 - one); substituted alpha - ketols such as 2 - methyl - 2 - hydroxypropiophenone; aromatic sulfonyl chlorides such as 2 - naphthalenesulfonyl chloride; photoactive oximes such as 1 - phenyl - 1,1 - propanedione - 2-(o - ethoxycarbonyl)-oxime; benzophenone - based compounds such as benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4 - phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4 - benzoyl - 4’ - methyldiphenyl sulfide, and 3,3’,4,4’ - tetra(t - butylperoxycarbonyl)benzophenone; thioxanthone - based compounds such as thioxanthone, 2 - chlorothioxanthone, 2 - methylthioxanthone, isopropylthioxanthone, 2,4 - diisopropylthioxanthone, and 2,4 - diethylthioxanthone;Triazine compounds such as 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine, 2-piperonyl-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphthalen-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphthalen-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine; Oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)], O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethylidene)hydroxylamine; Phosphine compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide; Quinone compounds such as 9,10-phenanthrenequinone, camphorquinone, ethylanthraquinone; Borate compounds; Carbazole compounds; Imidazole compounds; And metallocene compounds. The adhesive composition may contain one or more photoinitiators. Note that α-hydroxyalkylphenone tends to have a large absorption of light with a wavelength of 340 ± 10 nm.;

[0050] Another example of a photoinitiator is a compound having the chemical structure shown in the following formula (1) (hereinafter referred to as "chemical structure X") in the molecule.;

Chemical formula

[0051] R in the formula (1) 1 and R 2are, independently of each other, an alkyl group having 1 to 8 carbon atoms; -OH, an alkoxy group having 1 to 4 carbon atoms, -CN, -COOR 51 , -OOCR 52 , or -NR 53 R 54 wherein the hydrogen atom is replaced by an alkyl group having 1 to 4 carbon atoms; an alkenyl group having 3 to 6 carbon atoms; or, -CH₂-C₆H₄-R 55 . R 1 and R 2 may be bonded to each other to form an alkylene group having 2 to 9 carbon atoms, or an oxyalkylene group or an azaalkylene group having 3 to 6 carbon atoms. R 51 is an alkyl group having 1 to 8 carbon atoms. R 52 is an alkyl group having 1 to 4 carbon atoms. R 53 and R 54 are, independently of each other, a hydrogen atom, an alkyl group having 1 to 12 carbon atoms; -OH, an alkoxy group having 1 to 4 carbon atoms, -CN and -COOR 59 wherein the hydrogen atom is replaced by at least one group selected from the group consisting of an alkyl group having 2 to 4 carbon atoms; an alkenyl group having 3 to 5 carbon atoms; or a cyclohexyl group. R 53 and R 54 may be bonded to each other to form an alkylene group having 3 to 9 carbon atoms which may be interrupted by -O- or -N(R 60 )-. R 55 is an alkyl group having 1 to 4 carbon atoms. R 59 is an alkyl group having 1 to 4 carbon atoms. R 60 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group, a hydroxyalkyl group having 1 to 4 carbon atoms, -CH₂CH₂-COOR 61 or -CH₂CH₂CN. R 61 is an alkyl group having 1 to 4 carbon atoms.

[0052] X is -OR 56 , or -NR 57 R 58 . R 56 is a hydrogen atom, -SiR 62 ₃, an alkyl group having 1 to 8 carbon atoms, or an alkenyl group having 3 to 6 carbon atoms. R 57 and R 58is an alkyl group of C1-C12; -OH, an alkoxy group of C1-C4, -CN and -COOR 63 is a C2-C4 alkyl group in which a hydrogen atom is substituted by at least one group selected from the group consisting of; a C3-C5 alkenyl group; or a cyclohexyl group. R 57 and R 58 may be bonded to each other to form an alkylene group of C3-C9 which may be interrupted by -O- or -N(R 64 ). R 62 is an alkyl group of C1-C6. R 63 is an alkyl group of C1-C4. R 64 is a hydrogen atom, an alkyl group of C1-C4, an allyl group, a hydroxyalkyl group of C1-C4, -CH2CH2-COOR 65 or -CH2CH2CN. R 65 is an alkyl group of C1-C4.

[0053] In chemical structure X, in formula (1), it can be bonded to a hydrogen atom or a substituted structure of a hydrogen atom via the carbon atom indicated by *.

[0054] In the description of formula (1), the alkyl group, alkoxy group, alkenyl group, alkylene group, oxyalkylene group, azaalkylene group, and hydroxyalkyl group may all be either unbranched or branched. Also, including the description of formula (1), in this specification, the description of "Cn1-Cn2" (n1 and n2 are natural numbers) means that the number of carbon atoms is in the range of n1-n2.

[0055] In formula (1), R 1 and R 2 may be the same.

[0056] R1, R2 and X can take any combination of the above preferred examples.

[0057] The chemical structure X may be the structure represented by the following formula (2). In the chemical structure X of formula (2), when a substitution structure of a hydrogen atom is bonded to the carbon atom indicated by *, the substitution structure and, in formula (2), -COCR 1 XR 2 The group is in a para position relationship with respect to the benzene ring that the chemical structure X has.

Chemical formula

[0058] The photoinitiator may be a compound having two or more chemical structures X in one molecule.

[0059] The photoinitiator may be the compound represented by the following formula (3). The compound of formula (3) has two chemical structures X in one molecule. The two chemical structures X are each located at both ends of the molecule of the photoinitiator. More specifically, the two chemical structures X are bonded to each other at the carbon atom of the phenylene group indicated by * above by -A-.

Chemical formula

[0060] R in formula (3) 1 ’ and R 2 ’ are, with respect to each other, and, R 1 and R 2 are independently of, R 1 and R 2 and are groups that can be taken as. R 1 ’ and / or R 2 ’ may be the same as R 1 and / or R 2 R 1 , R 2 , R 1 ’, and R 2 ’ may all be the same.

[0061] X’ in formula (3) is, independently of X in formula (1), a group that can be taken as X. X’ and X may be the same.

[0062] A is -O-, -CYR 3 -, or -C(CH3)R 4 is.

[0063] Y is a hydrogen atom, -Cl, -Br, -O-R 71 , -NR 72 R 73 , or -S-R 74 is. R 3 is a hydrogen atom, a C1-C8 alkyl group, a C3-C6 alkenyl group, a benzyl group, -CH2-C6H4-R 75 , or a phenyl group. R 4 is a C1-C6 alkyl group or an alkylene group, and this alkylene group is bonded to the carbon atom of the phenylene group that the compound of formula (3) has.

[0064] R 71 is a hydrogen atom, -Si(R 76 )3, a C1-C12 alkyl group, a C2-C18 acyl group, -CO-NH-R 77 , a C2-C20 hydroxyalkyl group, a C2-C20 methoxyalkyl group, 3-R 78 -2-hydroxy-propyl group, 3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]-propyl group, 2,3-dihydroxy-propyl group, or a C2-C21 hydroxyalkyl group in which the carbon chain is interrupted by 1 to 9 oxygen atoms, or a C3-C25 alkyl group. R 72 and R 73 are, independently of each other, a C1-C12 alkyl group; -OH, a C1-C4 alkoxy group, -CN, and -COOR 79 a C2-C4 alkyl group in which a hydrogen atom is substituted by at least one group selected from the group consisting of; a C3-C5 alkenyl group; a cyclohexyl group; or a C7-C9 phenylalkyl group. R 72 and R 73 may be bonded to each other to form a C3-C9 alkylene group which may be interrupted by -O- or -N(R 80 )-. R 74is an alkyl group of C1-C18, hydroxyethyl group, 2,3-dihydroxypropyl group, cyclohexyl group, benzyl group, phenyl group, alkylphenyl group of C1-C12, -CH2-COOR 81 -CH2CH2-COOR 82 or -CH(CH3)-COOR 83 wherein. R 75 is an alkyl group of C1-C4. R 76 is an alkyl group of C1-C6. R 77 is an alkyl group of C1-C12. R 78 is an alkoxy group of C1-C18. R 79 is an alkyl group of C1-C4. R 80 is a hydrogen atom, an alkyl group of C1-C4, allyl group, benzyl group, hydroxyalkyl group of C1-C4, -CH2CH2-COOR 84 or -CH2CH2CN. R 81 , R 82 and R 83 are, independently of one another, an alkyl group of C1-C18. R 84 is an alkyl group of C1-C4.

[0065] In the description of formula (3), in the alkyl group, alkenyl group, acyl group, hydroxyalkyl group, methoxyalkyl group, alkoxy group, phenylalkyl group, the alkyl part and the alkylene group may be either unbranched or branched.

[0066] R in formula (3) 1 , R 2 , R 1 ’ and R 2 ’s preferred examples are the same as the preferred examples of R 1 and R 2 described above in the description of formula (1). The preferred examples of X' in formula (3) are the same as the preferred examples of X described above in the description of formula (1). A may be -CYR 3 -. Y may be a hydrogen atom. R 3 may be a hydrogen atom. When A is -CYR 3 - and Y and R3 They may both be hydrogen atoms. In other words, A may be -CH2-.

[0067] R in formula (3) 1 , R 2 , R 1 ’, R 2 ’, X, X’, and A can take any combination of the above preferred examples.

[0068] The photoinitiator may be a compound represented by the following formula (4). The compound of formula (4) is one type of the compound of formula (3).

Chemical formula

[0069] Specific examples of the photoinitiator are shown in the following formulas (5) to (9). The photoinitiator may be a compound represented by at least one formula selected from the group consisting of formulas (5) to (9), may be a compound represented by at least one formula selected from the group consisting of formulas (5) to (8), may be a compound represented by at least one formula selected from the group consisting of formulas (5) to (7), or may be a compound represented by formula (5). Note that the compound of formula (8) is derived from a vinyl compound having a chemical structure X in its side chain. More specifically, it is an oligomer of the vinyl compound.

[0070]

Chemical formula

[0071]

Chemical formula

[0072]

Chemical formula

[0073]

Chemical formula

[0074]

Chem.

[0075] The photoinitiators shown in Formulas (5) to (9) are commercially available as Omnirad 127D, Esacure KIP160, Esacure one, Esacure KIP150, and Omnirad 1173 (all manufactured by IGM Resins), respectively. The photoinitiator may be at least one selected from these groups.

[0076] Examples of specific photoinitiators are 1-hydroxycyclohexyl-phenyl ketone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)2-methylpropan-1-one. Among these, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)2-methylpropan-1-one is preferred. Each of the above photoinitiators is commercially available as Omnirad 184, Omnirad 819, and Omnirad 127 (all manufactured by IGM Resin).

[0077] The compounding amount of the photoinitiator in the pressure-sensitive adhesive composition is, for example, 20 parts by weight or less, 10 parts by weight or less, 5.0 parts by weight or less, 3.0 parts by weight or less, 1.0 parts by weight or less, 0.5 parts by weight or less, 0.3 parts by weight or less, 0.25 parts by weight or less, and even 0.2 parts by weight or less with respect to 100 parts by weight of the monomer group (a total of 100 parts by weight of the monomer group and its partial polymer). The lower limit of the compounding amount of the photoinitiator may be, for example, 0.01 parts by weight or more, 0.03 parts by weight or more, 0.05 parts by weight or more, and even 0.06 parts by weight or more with respect to 100 parts by weight of the monomer group.

[0078] <Crosslinking agent> The adhesive composition may contain a crosslinking agent. Examples of the crosslinking agent are polyfunctional monomers having two or more polymerizable functional groups in one molecule. The polyfunctional monomer may be a (meth)acrylic monomer. Examples of the polyfunctional monomer are monomers having two or more C=C bonds in one molecule, and monomers having one or more C=C bonds and one or more polymerizable functional groups such as epoxy groups, aziridine groups, oxazoline groups, hydrazine groups, and methylol groups in one molecule. The polyfunctional monomer is preferably a monomer having two or more C=C bonds in one molecule.

[0079] Examples of the polyfunctional monomer are polyfunctional acrylates such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol diacrylate (NDDA), 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate (esters of polyhydric alcohols and (meth)acrylic acid, etc.); allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, hexyl di(meth)acrylate. The polyfunctional monomer is preferably a polyfunctional acrylate, more preferably 1,9-nonanediol diacrylate, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate.

[0080] The blending amount of the crosslinking agent varies depending on the molecular weight, the number of functional groups, etc., but is, for example, 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, 0.5 part by weight or less, 0.3 part by weight or less, 0.2 part by weight or less, and even 0.15 part by weight or less with respect to 100 parts by weight of the monomer group. The lower limit of the blending amount may be, for example, 0.01 part by weight or more, 0.03 part by weight or more, 0.05 part by weight or more, 0.06 part by weight or more, 0.08 part by weight or more, and even 0.1 part by weight or more. The pressure-sensitive adhesive composition may not contain a crosslinking agent.

[0081] <Radical scavenger> As described above, the pressure-sensitive adhesive composition further contains a radical scavenger. The radical scavenger can limit the amount of radicals generated at high temperatures in the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition with the amount of radicals generated at high temperatures limited when formed into a pressure-sensitive adhesive sheet is suitable for use in an optical laminate in an environment where high temperatures need to be considered.

[0082] In addition to the nitrogen atom-containing monomer, in a pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing a radical scavenger in an appropriate content, the durability against the heat shock test is less likely to decrease. Specifically, when the optical laminate using the above pressure-sensitive adhesive sheet is subjected to the heat shock test, the above-mentioned peeling and foaming are less likely to occur. This is presumably because in a pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing a radical scavenger in an appropriate content, the molecular weight of the polymer is less likely to decrease in the heat shock test, and as a result, the cohesive force of the pressure-sensitive adhesive sheet is also less likely to decrease. By suppressing the decrease in the cohesive force of the pressure-sensitive adhesive sheet in this way, it is presumed that the durability against the heat shock test is less likely to decrease.

[0083] The radical scavenger may have a polymerizable unsaturated double bond and may correspond to a part of the monomers constituting the above-described monomer group. In this case, the content of the radical scavenger in the pressure-sensitive adhesive composition is, for example, 30 parts by weight or less, 29 parts by weight or less, 28 parts by weight or less, 27 parts by weight or less, 26 parts by weight or less, 25 parts by weight or less, 24 parts by weight or less, 23 parts by weight or less, 22 parts by weight or less, 21 parts by weight or less, and further 20 parts by weight or less out of 100 parts by weight of the monomer group. Also, in this case, the content of the radical scavenger is, for example, 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, 4 parts by weight or more, 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, 10 parts by weight or more, 11 parts by weight or more, 12 parts by weight or more, 13 parts by weight or more, 14 parts by weight or more, and further 15 parts by weight or more out of 100 parts by weight of the monomer group. If the radical scavenger is within the above content range, in the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition, the durability at a high temperature of 100°C or higher is improved, and the durability against the heat shock test is less likely to decrease.

[0084] The radical scavenger may not have a polymerizable unsaturated double bond. In this case, the content of the radical scavenger in the pressure-sensitive adhesive composition is, for example, 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, 0.9 part by weight or less, 0.8 part by weight or less, 0.7 part by weight or less, 0.6 part by weight or less, and further 0.5 part by weight or less with respect to 100 parts by weight of the monomer group. Also, in this case, the content of the radical scavenger is, for example, 0.01 part by weight or more, 0.02 part by weight or more, 0.03 part by weight or more, 0.04 part by weight or more, 0.05 part by weight or more, 0.06 part by weight or more, 0.07 part by weight or more, 0.08 part by weight or more, 0.09 part by weight or more, and further 0.1 part by weight or more. If the radical scavenger is within the above content range, in the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition, the durability at a high temperature of 100°C or higher is improved, and the durability against the heat shock test is less likely to decrease.

[0085] The radical scavenger preferably contains at least one selected from the group consisting of a phenoxy radical scavenger, an amine radical scavenger, and a phosphite radical scavenger, and more preferably contains at least one of a phenoxy radical scavenger and a phosphite radical scavenger. According to such a configuration, in the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition, the durability at a high temperature of 100° C. or higher is improved.

[0086] When the phenoxy radical scavenger has a polymerizable unsaturated double bond, it is preferably a phenoxy (meth) acrylate compound. In the present specification, the phenoxy type is a concept including the phenol type. When the phenoxy radical scavenger does not have a polymerizable unsaturated double bond, it is preferably at least one selected from the group consisting of a phenolic antioxidant and a hindered phenolic antioxidant, and more preferably a hindered phenolic antioxidant.

[0087] Examples of the phenoxy (meth) acrylate compound are phenoxy (meth) acrylate, phenoxyethyl (meth) acrylate, and phenoxyethoxyethyl (meth) acrylate.

[0088] Examples of phenolic antioxidants are monophenolic antioxidants, bisphenolic antioxidants, and polymeric phenolic antioxidants. Examples of monophenolic antioxidants are 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl) propionate. Examples of bisphenolic antioxidants are 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl] 2,4,8,10-tetraoxaspiro[5,5]undecane. Examples of polymeric phenolic antioxidants are 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid] glycol ester, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H, 3H, 5H)trione, and tocopherol.

[0089] The hindered phenolic antioxidant may have a structure in which a tertiary butyl group is bonded to at least one carbon atom adjacent to the carbon atom on the aromatic ring to which the OH group of the phenol is bonded. Examples of the hindered phenolic antioxidant are dibutylhydroxytoluene (BHT); and Irganox 1010, Irganox 1010FF, Irganox 1035, Irganox 1035FF, Irganox 1076, Irganox 1076FD, Irganox 1076DWJ, Irganox 1098, Irganox 1135, Irganox 1330, Irganox 1726, Irganox 1425WL, Irganox 1520L, Irganox 245, Irganox 245FF, Irganox 259, Irganox 3114, Irganox 565 and Irganox 295 (all are trade names and are manufactured by BASF).

[0090] The amine-based radical scavenger is preferably an amine-based antioxidant, more preferably a hindered amine-based antioxidant. The hindered amine-based antioxidant may have at least one hindered piperazine group in one molecule. Examples of the hindered amine-based antioxidant are Adeka Stab LA-63, Adeka Stab LA-63P, Adeka Stab LA-52 and Adeka Stab LA-57 (all are trade names and are manufactured by ADEKA).

[0091] The phosphite-based radical scavenger is preferably a phosphite-based antioxidant. Examples of the phosphite-based antioxidant are triphenyl phosphite, diphenylisodecyl phosphite and phenyldiisodecyl phosphite; and Adeka Stab 2112, Adeka Stab 2112RG, Adeka Stab 1178 and Adeka Stab 3010 (all are trade names and are manufactured by ADEKA).

[0092] The radical scavenger (e.g., antioxidant) preferably has a phenoxy structure. According to the studies by the present inventors, a radical scavenger having a phenoxy structure is particularly suitable for improving the durability at high temperatures of 100 °C or higher in an adhesive sheet formed from an adhesive composition.

[0093] The molecular weight of the radical scavenger (e.g., antioxidant) may be 1000 or less, 900 or less, 850 or less, 800 or less, 700 or less, 600 or less, 500 or less, 450 or less, and even 400 or less. The lower limit of the molecular weight is, for example, 100 or more. According to the studies by the present inventors, a radical scavenger having a molecular weight within the above range is particularly suitable for suppressing the amount of radicals generated in an adhesive sheet formed from an adhesive composition.

[0094] The radical scavenger (e.g., antioxidant) may be liquid at room temperature (25 °C).

[0095] The adhesive composition may contain additives other than those described above. Examples of the additives are a chain transfer agent, a silane coupling agent, a viscosity modifier, a tackifier, a plasticizer, a softening agent, an anti-aging agent, a filler, a colorant, an antioxidant, a surfactant, an antistatic agent, and an ultraviolet absorber. The adhesive composition may not contain an additive.

[0096] The viscosity of the adhesive composition is preferably 5 to 100 poises. An adhesive composition having a viscosity within the above range is particularly suitable for forming the adhesive sheet 1.

[0097] The content of the solvent in the adhesive composition is, for example, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, and even 0.5% by weight or less. The adhesive composition may not substantially contain a solvent. Not substantially containing a solvent means that solvents and the like derived from additives and the like are allowed at a content of, for example, 0.1% by weight or less, preferably 0.05% by weight or less, and more preferably 0.01% by weight or less. Also, the content of the solvent in the adhesive sheet 1 may be within the above range. The adhesive sheet 1 may not substantially contain a solvent.

[0098] [Adhesive sheet] The adhesive sheet of the present embodiment is formed from an adhesive composition. Specifically, by irradiating the adhesive composition with light to generate a polymer from at least one selected from the group consisting of a monomer group and a partial polymer of the monomer group, an adhesive sheet is formed (see "Adhesive Sheet 1" in FIG. 1).

[0099] <Method for manufacturing an adhesive sheet> An example of the method for manufacturing the adhesive sheet of the present embodiment is shown in FIG. 1. The adhesive sheet 1 is formed, for example, by irradiating light 24 onto a first laminate 20 including a base sheet 21, a coating layer 22 containing an adhesive composition, and a release liner 23 in this order. The coating layer 22 is cured by the irradiation of the light 24 to become the adhesive sheet 1. The light 24 is typically irradiated from the side of the base sheet 21 using a light source 28. At this time, the light 24 passes through the base sheet 21 and reaches the coating layer 22 to cure the coating layer 22. However, the light 24 may be irradiated from the side of the release liner 23, or may be irradiated from both the side of the release liner 23 and the side of the base sheet 21.

[0100] The formed adhesive sheet 1 is sandwiched between the base sheet 21 and the release liner 23 until the release liner 23 is peeled off, and constitutes a part of a second laminate 27. By peeling off the release liner 23 from the second laminate 27, a third laminate 25 including the base sheet 21 and the adhesive sheet 1 is obtained. In the third laminate 25, the surface of the adhesive sheet 1 is exposed to the outside. An optical film can be laminated directly or via another layer on the exposed surface of the adhesive sheet 1.

[0101] The light 24 is, for example, visible light or ultraviolet light having a wavelength shorter than 450 nm. The light may include light having a wavelength in the same region as the absorption wavelength of the photoinitiator contained in the pressure-sensitive adhesive composition. Light obtained by cutting short-wavelength light having a wavelength of 300 nm or less with a filter or the like may be irradiated. Cutting the short-wavelength light is suitable for suppressing deterioration of the base material sheet 21 and / or the release liner 23 by the light 24. The light source of the light is, for example, a light irradiation device including an ultraviolet irradiation lamp. Examples of the ultraviolet irradiation lamp are ultraviolet light LED, low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, xenon lamp, microwave-excited mercury lamp, black light lamp, chemical lamp, germicidal lamp, low-pressure discharge mercury lamp, and excimer laser. Two or more ultraviolet irradiation lamps may be combined. According to the ultraviolet light LED, the band of the irradiated ultraviolet light can be made narrower than when using other light sources.

[0102] When using an ultraviolet light LED as the light source, an LED having a peak wavelength at 340 ± 10 nm (hereinafter referred to as "LED340") may be selected. According to the studies of the present inventors, the use of LED340 may contribute to at least one selected from, for example, an improvement in the polymerization rate of the monomer group in the pressure-sensitive adhesive sheet 1, an improvement in the molecular weight of the polymer, and a reduction in the residual amount of the photoinitiator, as compared with the case of using a black light source. Further, according to LED340, there is a tendency that heat generation can be suppressed as compared with the case of using an LED having a peak wavelength near 365 nm. Suppression of heat generation can contribute to control of the temperature of the coating layer 22. Note that the peak wavelength means the wavelength at which the intensity becomes a maximum value in the spectrum showing the relationship between the wavelength and intensity of light.

[0103] The illuminance of the light 24 irradiated on the first laminate 20 (specifically, the coating layer 22) is, for example, 2.0 to 30 mW / cm 2 is. The illuminance is 2.5 mW / cm 2 or more, 3.0 mW / cm 2 or more, 3.5 mW / cm 2 or more, 4.0 mW / cm 2 or more, 5.0 mW / cm 2 or more, 6.0 mW / cm 27.0 mW / cm or more 2 8.0 mW / cm or more 2 9.0 mW / cm or more 2 10 mW / cm or more, and even more 2 It may be so. The upper limit of the illuminance is, for example, 25 mW / cm 2 or less, 20 mW / cm 2 or less, and even more 15 mW / cm 2 It may be so.

[0104] The time for irradiating the first laminate 20 (specifically, the coating layer 22) with light 24 is, for example, 10 seconds to 1000 seconds, and it may be 60 seconds or more, 100 seconds or more, 150 seconds or more, 200 seconds or more, 250 seconds or more, and even more 300 seconds or more. The upper limit of the time is, for example, 800 seconds or less, 600 seconds or less, 500 seconds or less, 400 seconds or less, 350 seconds or less, 300 seconds or less, and even more 250 seconds or less. The irradiation of the light 24 may be continuous or intermittent.

[0105] The integrated light quantity of the light 24 with respect to the first laminate 20 (specifically, the coating layer 22) is, for example, 25 mJ / cm 2 or more, 100 mJ / cm 2 or more, 250 mJ / cm 2 or more, 500 mJ / cm 2 or more, 750 mJ / cm 2 or more, 850 mJ / cm 2 or more, 1000 mJ / cm 2 or more, 1250 mJ / cm 2 or more, and even more 1500 mJ / cm 2 or more. The upper limit of the integrated light quantity is not particularly limited, and it is, for example, 3000 mJ / cm 2 or less, 2500 mJ / cm 2 or less, 2000 mJ / cm 2 or less, 1750 mJ / cm 2 or less, 1500 mJ / cm 2 or less, 1250 mJ / cm 2 or less, and even more 1000 mJ / cm 2The following may be the case. The adhesive sheet 1 is suitable for formation with a low integrated light quantity, and thus, the adhesive sheet 1 is excellent in productivity.

[0106] Examples of the base material of the release liner 23 (hereinafter referred to as "liner base material") are resin films. Examples of the resin that can be included in the liner base material are polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resin, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

[0107] The release liner 23 may include a layer other than the liner base material. The release liner 23 may include a release layer. The release liner 23 includes, for example, a liner base material and a release layer formed on one surface of the liner base material. This release liner 23 can be used such that the release layer is on the side of the coating layer 22. The release layer is typically a cured layer of a release agent composition containing a release agent. Various release agents such as silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, fatty acid amide-based release agents, and silica powder can be used as the release agent.

[0108] The release liner 23 may be in a sheet form or a long strip form.

[0109] Examples of the base material sheet 21 are resin films. Examples of the resin contained in the base material sheet 21 are the same as the examples of the resin that can be included in the liner base material.

[0110] The thickness of the base material sheet 21 is, for example, 10 to 200 μm, and may be 25 to 150 μm.

[0111] The base material sheet 21 may be provided with a release layer on the surface on the side of the coating layer 22. Examples of the release layer that the base material sheet 21 can include are the same as the examples of the release layer that the release liner 23 can include. Both the release liner 23 and the base material sheet 21 may be provided with a release layer.

[0112] For the base material sheet 21, usually, a sheet with a peeling force from the adhesive sheet 1 larger than that of the release liner 23 can be selected.

[0113] The base material sheet 21 may be in a single-sheet form or a long-strip form.

[0114] The first laminate 20 is formed, for example, by forming the coating layer 22 on the base material sheet 21 (or the release liner 23) and disposing the release liner 23 (or the base material sheet 21) on the formed coating layer 22. Also, the first laminate 20 may be formed by applying an adhesive composition so as to flow into the space between the base material sheet 21 and the release liner 23 held at a predetermined interval with their main surfaces facing each other.

[0115] For the formation of the coating layer 22, various coating methods such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, die coating, etc. can be applied.

[0116] The thickness of the coating layer 22 can be adjusted according to the thickness of the target adhesive sheet 1, and is, for example, 5 to 100 μm, and may be 5 to 50 μm, 5 to 25 μm, or even 5 to 20 μm.

[0117] The first laminate 20 may include a long-strip base material sheet 21, a long-strip coating layer 22, and a long-strip release liner 23. In other words, it may be in a long-strip form. The long-strip first laminate 20 is obtained, for example, by forming the coating layer 22 between the base material sheet 21 and the release liner 23 while conveying the base material sheet 21 and the release liner 23 fed out from a wound body.

[0118] <Weight-average molecular weight of the polymer contained in the pressure-sensitive adhesive sheet> The weight-average molecular weight (Mw) of the polymer contained in the pressure-sensitive adhesive sheet 1 is, for example, 600,000 or more, and may be 650,000 or more, 700,000 or more, 750,000 or more, 800,000 or more, 850,000 or more, 900,000 or more, 950,000 or more, 1,000,000 or more, 1,100,000 or more, 1,200,000 or more, 1,300,000 or more, and even 1,400,000 or more. Note that Mw is the weight-average molecular weight without a crosslinking agent. The upper limit of Mw is not particularly limited and is, for example, 3,000,000 or less. The Mw of the polymer is measured by GPC (gel permeation chromatography) and determined from the value calculated by polystyrene conversion.

[0119] The polymerization rate of the monomer group in the pressure-sensitive adhesive sheet 1 may be 97.5% or more, 98% or more, and even 98.5% or more. The upper limit of the polymerization rate is, for example, 99.99% or less. A high polymerization rate contributes, for example, to suppressing the odor of the pressure-sensitive adhesive sheet 1.

[0120] In the pressure-sensitive adhesive sheet 1, both the molecular weight of the polymer and the polymerization rate of the monomer group can be increased. The weight-average molecular weight (Mw) of the polymer contained in the pressure-sensitive adhesive sheet 1 may be 600,000 or more, and the polymerization rate of the monomer group in the pressure-sensitive adhesive sheet 1 may be 98% or more. Mw and the polymerization rate may each be within the numerical ranges described above.

[0121] <Gel fraction of the pressure-sensitive adhesive sheet> The gel fraction of the adhesive sheet 1 can be evaluated as follows. A test piece of about 0.1 g is taken from the adhesive sheet 1, wrapped in a polytetrafluoroethylene porous sheet (average pore diameter 0.2 μm, trade name "NTF1122", manufactured by Nitto Denko Corporation), and then tied with a kite string to obtain a measurement sample. Next, the weight of the obtained measurement sample (weight C before immersion) is measured. The weight C before immersion is the total weight of the test piece, the polytetrafluoroethylene porous sheet, and the kite string. Separately, the weight B of the packaging bag, which is the total weight of the polytetrafluoroethylene porous sheet and the kite string, is measured. Next, the measurement sample is placed in a 50 mL container filled with ethyl acetate and left standing at 23 °C for 7 days. After standing, the measurement sample is taken out of the container, transferred to an aluminum cup, and the ethyl acetate is removed by drying at 130 °C for 2 hours using a dryer. The weight of the measurement sample after drying (weight A after immersion) is measured. The value calculated from the following formula is specified as the gel fraction of the adhesive sheet 1. Gel fraction G (%) = (A - B) / (C - B) × 100

[0122] The gel fraction of the adhesive sheet 1 (gel fraction Ga described later) is, for example, 55% or more, and may be 60% or more, 65% or more, 70% or more, 75% or more, 78% or more, 80% or more, more than 80%, 81% or more, 82% or more, 83% or more, 84% or more, and even 85% or more. The upper limit of the gel fraction may be 95% or less, 94% or less, 93% or less, 92% or less, 91% or less, 90% or less, and even 89% or less.

[0123] When left standing for 24 hours in an environment of 105 °C (hereinafter referred to as "high-temperature standing"), the gel fraction of the adhesive sheet 1 after high-temperature standing (gel fraction Gb described later) is, for example, 55% or more, and may be 60% or more, 65% or more, 70% or more, 75% or more, 78% or more, 80% or more, more than 80%, 81% or more, 82% or more, 83% or more, 84% or more, and even 85% or more. The upper limit of the gel fraction may be 95% or less, 94% or less, 93% or less, 92% or less, 91% or less, 90% or less, and even 89% or less.

[0124] The absolute value |Ga - Gb| of the difference between the gel fraction Ga of the pressure-sensitive adhesive sheet 1 before high-temperature storage and the gel fraction Gb of the pressure-sensitive adhesive sheet 1 after high-temperature storage is, for example, 10% or less, and may be 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or even 1% or less. According to such a configuration, since the gel fraction does not change much before and after high-temperature storage, it becomes easier to improve the durability of the pressure-sensitive adhesive sheet 1 at a high temperature of 100°C or higher.

[0125] The thickness of the pressure-sensitive adhesive sheet 1 is, for example, 2 to 70 μm. The thickness may be 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the thickness may be 5 μm or more, 10 μm or more, or even 15 μm or more. A thin pressure-sensitive adhesive sheet 1, for example, a pressure-sensitive adhesive sheet 1 with a thickness of 30 μm or less, is likely to be inhibited from polymerization by oxygen in the environment during formation by photocuring. On the other hand, the pressure-sensitive adhesive sheet 1 is suitable for formation with a low integrated light amount, in other words, suitable for formation by photocuring in a short time. Therefore, even in the case of a thin sheet, the influence of polymerization inhibition can be suppressed. Further, the pressure-sensitive adhesive sheet 1 is suitable for suppressing foaming in a high-temperature environment and peeling from an adherend even when the thickness is, for example, 30 μm or less. The adherend is, for example, a glass substrate.

[0126] [Optical laminate] An example of the optical laminate of the present embodiment is shown in FIG. 2. The optical laminate 30 in FIG. 2 includes a pressure-sensitive adhesive sheet 1 and an optical film 2. The pressure-sensitive adhesive sheet 1 and the optical film 2 are in contact with each other. The pressure-sensitive adhesive sheet 1 is a photocurable pressure-sensitive adhesive sheet formed from the above-described pressure-sensitive adhesive composition. The pressure-sensitive adhesive sheet 1 contains a polymer having a structural unit derived from a nitrogen atom-containing monomer as described above.

[0127] [Optical film] Examples of the optical film 2 are a polarizing film, a retardation film, and a laminated film including a polarizing film and / or a retardation film. However, the optical film 2 is not limited to the above examples. The optical film 2 may include a glass-made film.

[0128] The optical film 2 is a polarizing film, and the adhesive sheet 1 may be in contact with the polarizing film. Among optical films, polarizing films tend to have large dimensional changes due to heat. The dimensional change of the polarizing film can be a factor in peeling from the adhesive film. Therefore, the present invention is particularly advantageous when the optical laminate further includes a polarizing film.

[0129] The polarizing film may contain a polarizer. The polarizing film includes, for example, a polarizer and a transparent protective film. The transparent protective film is disposed in contact with, for example, the main surface (the surface having the largest area) of the polarizer. The polarizer may be disposed between two transparent protective films. The transparent protective film may be disposed on at least one surface of the polarizer.

[0130] The polarizer is not particularly limited. For example, a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film is adsorbed with a dichroic substance such as iodine or a dichroic dye and uniaxially stretched; examples include polyene-based oriented films such as a dehydrated product of polyvinyl alcohol and a dehydrochlorinated product of polyvinyl chloride. The polarizer typically consists of a polyvinyl alcohol-based film (the polyvinyl alcohol-based film includes an ethylene-vinyl acetate copolymer-based partially saponified film) and a dichroic substance such as iodine.

[0131] The thickness of the polarizer is not particularly limited. For example, it is 80 μm or less, and may be 50 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the thickness of the polarizer is not particularly limited. For example, it is 1 μm or more, and may be 5 μm or more, 10 μm or more, or even 15 μm or more. A thin polarizer (for example, having a thickness of 20 μm or less) has suppressed dimensional changes and can contribute to improving the durability of the optical laminate, particularly the durability at high temperatures.

[0132] As the material of the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, and isotropy is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material of the transparent protective film may be a thermosetting resin or an ultraviolet curable resin such as a (meth)acrylic type, urethane type, acrylic urethane type, epoxy type, or silicone type. When the polarizing film has two transparent protective films, the materials of the two transparent protective films may be the same as each other or different from each other. For example, a transparent protective film made of a thermoplastic resin is bonded via an adhesive to one main surface of the polarizer, and a transparent protective film made of a thermosetting resin or an ultraviolet curable resin is bonded via an adhesive to the other main surface of the polarizer. The transparent protective film may contain one or more arbitrary additives. Examples of the additives include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.

[0133] The thickness of the transparent protective film can be appropriately determined, but generally it is about 5 to 200 μm from the viewpoints of workability such as strength and handleability, and thin film properties.

[0134] The polarizer and the transparent protective film are usually adhered via an aqueous adhesive or the like. Examples of the aqueous adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl latex, an aqueous polyurethane, and an aqueous polyester. Examples of other adhesives other than the above adhesives include an ultraviolet curable adhesive and an electron beam curable adhesive. The adhesive for an electron beam curable polarizing film exhibits suitable adhesiveness to various transparent protective films. The adhesive may contain a metal compound filler.

[0135] In the polarizing film, instead of the transparent protective film, a retardation film or the like can also be formed on the polarizer. Another transparent protective film or a retardation film or the like can also be provided on the transparent protective film.

[0136] Regarding the transparent protective film, a hard coat layer may be provided on the surface facing the surface adhered to the polarizer, and treatment for the purpose of antireflection, anti-sticking, diffusion, antiglare, etc. can also be performed.

[0137] The polarizing film may be a circularly polarizing film.

[0138] The thickness of the polarizing film is, for example, 500 μm or less, and may be 300 μm or less, 200 μm or less, 100 μm or less, and further 60 μm or less. The lower limit of the thickness is, for example, 10 μm or more, 25 μm or more, and further 40 μm or more.

[0139] The retardation film is a film having birefringence in the in-plane direction and / or the thickness direction. The retardation film is, for example, a stretched resin film or a film in which a liquid crystal material is oriented and immobilized.

[0140] The retardation film can be selected from any film adjusted to appropriate refractive indices (nx, ny, nz). Here, "nx" is the refractive index in the direction where the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. The retardation film may be a λ / 4 plate, a λ / 2 plate, a retardation film for antireflection (see, for example, paragraphs 0221, 0222, 0228 of JP-A-2012-133303), a retardation film for viewing angle compensation (see, for example, paragraphs 0225, 0226 of JP-A-2012-133303), or a tilted alignment retardation film for viewing angle compensation (see, for example, paragraph 0227 of JP-A-2012-13303). The retardation film is not limited to the above examples as long as it has birefringence in the in-plane direction and / or the thickness direction. The retardation value, the arrangement angle, the three-dimensional birefringence, whether it is a single layer or a multilayer, etc. of the retardation film are also not limited. Known films can be used for the retardation film.

[0141] The thickness of the optical film 2 is, for example, 1 to 200 μm.

[0142] The optical film 2 may be a single layer or a laminated film composed of two or more layers. When the optical film 2 is a laminated film, the adhesive sheet 1 may be used for bonding each layer.

[0143] The optical laminate 30 may include other layers other than the adhesive sheet 1 and the optical film 2. Another layer may be disposed between the adhesive sheet 1 and the optical film 2, but it is preferable that the adhesive sheet 1 and the optical film 2 are in contact with each other.

[0144] The optical laminate 30 is used, for example, in an optical laminate or an image display device. However, the use of the optical laminate 30 is not limited to the above examples.

[0145] Another example of the optical laminate according to this embodiment is shown in FIG. 3. The optical laminate 30A in FIG. 3 includes the above-described adhesive sheet 1. The optical laminate 30A has a laminated structure in which a separator 3, an adhesive sheet 1, and an optical film 2 are laminated in this order. The optical laminate 30A can be used as an optical film with an adhesive sheet by peeling off the separator 3.

[0146] <Separator> The separator 3 is typically a resin film. Examples of the resin constituting the separator 3 are polyesters such as polyethylene terephthalate (PET), polyolefins such as polyethylene and polypropylene, polycarbonate, acrylic, polystyrene, polyamide, and polyimide. A release treatment may be performed on the contact surface of the separator 3 with the adhesive sheet 1. The release treatment is, for example, a treatment with a silicone compound. However, the separator 3 is not limited to the above examples. The separator 3 is peeled off when the optical laminate 30A is used, for example, when it is attached to an image forming layer.

[0147] Another example of the optical laminate according to this embodiment is shown in FIG. 4. The optical laminate 30B in FIG. 4 includes the above-described adhesive sheet 1. The optical laminate 30B has a laminated structure in which a separator 3, an adhesive sheet 4, a retardation film 2B, an adhesive sheet 1, and a polarizing film 2A are laminated in this order. After peeling off the separator 3, the optical laminate 30B is used, for example, by attaching it to an image forming layer of an image display device.

[0148] A known adhesive sheet can be used for the adhesive sheet 4. The adhesive sheet 1 may be used for the adhesive sheet 4.

[0149] Another example of the optical laminate according to this embodiment is shown in FIG. 5. The optical laminate 30C in FIG. 5 includes the above-described adhesive sheet 1. The optical laminate 30C has a laminated structure in which a separator 3, an adhesive sheet 4, an optical film (retardation film) 2B, an adhesive sheet 1, an optical film (polarizing film) 2A, and a transparent protective film 5 are laminated in this order. After peeling off the separator 3, the optical laminate 30C is used, for example, by attaching it to an image forming layer of an image display device.

[0150] As the adhesive sheet 4, a known adhesive sheet can be used. The adhesive sheet 1 may be used as the adhesive sheet 4.

[0151] The transparent protective film 5 has a function of protecting the outermost optical film 2 (polarizing film 2A) during the distribution and storage of the optical laminate 30C, and also when the optical laminate 30C is incorporated into an image display device. Further, in the state of being incorporated into the image display device, the transparent protective film 5 may function as a window to the external space. The transparent protective film 5 is typically a resin film. The resin constituting the transparent protective film 5 is, for example, polyester typified by PET, polyolefin typified by polyethylene and polypropylene, acrylic, cycloolefin, polyimide, and polyamide, and polyester is preferred. However, the transparent protective film 5 is not limited to the above examples. The transparent protective film 5 may be a glass film or a laminated film including a glass film. The transparent protective film 5 may be subjected to surface treatments such as antiglare, antireflection, and antistatic.

[0152] The transparent protective film 5 may be joined to the optical film 2 by any adhesive. Joining by the adhesive sheet 1 is also possible.

[0153] Another example of the optical laminate of the present embodiment is shown in FIG. 6. The optical laminate 30D in FIG. 6 includes the above-described adhesive sheet 1. The optical laminate 30D has a laminated structure in which a first retardation film 21D, a second retardation film 22D, a polarizer 23D, and a transparent protective film 24D are laminated in this order. The first retardation film 21D and the second retardation film 22D can each be selected from the above examples of the retardation film. The optical laminate 30D is used, for example, by being attached to the image forming layer of an image display device.

[0154] The optical laminate of the present embodiment may include any layer other than the layers described above. As long as the optical laminate of the present embodiment includes the adhesive sheet 1 and the optical film 2, it may have any configuration. The optical laminate of the present embodiment may include other films such as an antireflection film, a light diffusion film, a brightness enhancement film, and an electromagnetic wave shielding film.

[0155] The optical laminate of the present embodiment can be distributed and stored, for example, as a wound body obtained by winding a strip-shaped optical laminate or as a sheet-like optical laminate.

[0156] The optical laminate of the present embodiment is typically used in an image display device. The image display device is, for example, an EL display typified by a liquid crystal display, an organic EL display, and an inorganic EL display.

[0157] [Image display device] An example of an image display device according to an embodiment of the present invention is shown in FIG. 7. The image display device 50 in FIG. 7 has the optical laminate 30C in FIG. 5 (however, excluding the separator 3). Specifically, the image display device 50 has a laminated structure in which a substrate 7, an image forming layer (for example, an organic EL layer or a liquid crystal layer) 6, an adhesive sheet 4, an optical film (retardation film) 2B, an adhesive sheet 1, an optical film (polarizing film) 2A, and a protective film 5 are laminated in this order. The optical laminate (in FIG. 7, the adhesive sheet 4, the optical film (retardation film) 2B, the adhesive sheet 1, the optical film (polarizing film) 2A, and the protective film 5) may be another optical laminate including the adhesive sheet 1. The substrate 7 and the image forming layer 6 may have the same configurations as the substrate and the image forming layer provided in a known image display device, respectively.

Example

[0158] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples shown below.

[0159] [Preparation of Adhesive Composition] (Monomer Syrup A1) 97.1 parts by weight of n-butyl acrylate (BA) and 2.9 parts by weight of acrylic acid (AA), and 0.2 parts by weight of Omnirad 127D (manufactured by IGM Resin) as a photoinitiator were charged into a four-necked flask. Next, monomer syrup A1 in which the monomer was partially photopolymerized was obtained by irradiating the liquid in the flask with ultraviolet rays under a nitrogen atmosphere. The ultraviolet irradiation was carried out until the viscosity of the liquid in the flask (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 °C) reached 20 Pa·s.

[0160] (Monomer syrup A2) Monomer syrup A2 was prepared in the same manner as monomer syrup A1, except that the blending amount of the monomer was changed as shown in Table 1.

[0161]

Table 1

[0162] The abbreviations in Table 1 are as follows. BA: n-butyl acrylate AA: acrylic acid HBA: 4-hydroxybutyl acrylate Omnirad 127D: 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one (Omnirad 127D, manufactured by IGM Resin)

[0163] (Adhesive compositions C1 to C9) Next, a monomer syrup, a monomer, a crosslinking agent, and a radical scavenger were mixed so as to have the compositions shown in Table 2 below, and photocurable adhesive compositions C1 to C9 were obtained. The crosslinking agent and the radical scavenger were blended so as to have the blending amounts shown in Table 3 (final composition of the adhesive composition) described later.

[0164]

Table 2

[0165] The abbreviations in Table 2 are as follows. AA: Acrylic acid NVP: N-Vinyl-2-pyrrolidone PEA: Phenoxyethyl acrylate HBA: 4-Hydroxybutyl acrylate BzA: Benzyl acrylate NDDA: 1,9-Nonanediol diacrylate Adeka Stab LA-52: Tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate (Adeka Stab LA-52 (hindered amine light stabilizer), manufactured by ADEKA Corporation) Adeka Stab 2112: 3,9-Bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (Adeka Stab 2112 (phosphite antioxidant), manufactured by ADEKA Corporation) Irganox 1010: Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (Irganox 1010 (hindered phenol antioxidant), manufactured by BASF Corporation) Irganox 1135: C7-C9 branched alkyl ester of 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid (Irganox 1135 (hindered phenol antioxidant), manufactured by BASF Corporation)

[0166] The final composition of the monomers contained in each adhesive composition is shown in Table 3 below. The abbreviations in Table 3 are the same as those in Tables 1 and 2. In Table 3, the monomer (PEA) indicated by (*) also functions as a radical scavenger. Then, as described later, when obtaining an adhesive sheet from the adhesive composition, the monomer (PEA) copolymerizes with the monomers constituting the monomer group and is incorporated into the polymer. Thus, in the adhesive sheet, the blending amount of the radical scavenger incorporated into the polymer is described in the "monomer" column in Table 3 as the blending amount per 100 parts by weight of the monomer group. On the other hand, as described later, when obtaining an adhesive sheet from the adhesive composition, the radical scavenger (PEA) is not incorporated into the polymer but is contained in the adhesive sheet as an additive separate from the polymer. Thus, in the adhesive sheet, the blending amount of the radical scavenger contained in the adhesive sheet as an additive separate from the polymer is described in the "radical scavenger" column in Table 3 as the blending amount relative to 100 parts by weight of the monomer group.

[0167] [Table 3]

[0168] [Production of Adhesive Sheet] [Example 1] [Production of Release Liner] 30 parts by weight of an addition reaction-curing silicone (LTC761 containing a hexenyl group-containing polyorganosiloxane, 30 wt% toluene solution, manufactured by Toray Dow Corning), 0.9 parts by weight of a release control agent (BY24-850 containing an unreacted silicone resin, manufactured by Toray Dow Corning), 2 parts by weight of a curing catalyst (SRX212 containing a platinum catalyst, manufactured by Toray Dow Corning), and a toluene / hexane mixed solvent (volume ratio 1:1) as a diluting solvent were mixed to obtain a silicone-based release agent composition. The concentration of the silicone solid content in the release agent composition was 1.0 wt%. Next, the release agent composition was applied to one side of a liner substrate (Lumirror XD500P, a polyester film, thickness 75 μm) with a wire bar and heated at 130°C for 1 minute to produce a release liner having a release layer (thickness 60 nm) on one side.

[0169] (Preparation of Adhesive Sheet) An adhesive composition was applied to one side of a base sheet (PET separator, manufactured by Mitsubishi Chemical Corporation, MRF38) using an applicator to form a coating layer (thickness: 15 μm). Next, a release liner was placed on the formed coating layer to obtain a first laminate. The release liner was placed such that the release layer was in contact with the coating layer. Next, from the side of the base sheet of the first laminate, light was irradiated under the conditions of an illuminance of 9 mW / cm 2 and an irradiation time of 56 seconds (the integrated light amount was 500 mJ / cm 2 ). An LED was used as the light source, and the peak wavelength of the irradiated light was 340 nm. Further, from the side of the base sheet of the first laminate, light was irradiated under the conditions of an illuminance of 9 mW / cm 2 and an irradiation time of 22 seconds (the integrated light amount was 200 mJ / cm 2 ). A metal halide lamp was used as the light source. Thereby, the coating layer was photocured to obtain the adhesive sheet of Example 1 (thickness: 15 μm) sandwiched between the base sheet and the release liner. The illuminance of the light was measured using an illuminance meter (manufactured by Topcon Technohouse Co., Ltd., UD-T3040T2) at a position near the incident surface of ultraviolet rays on the base sheet.

[0170] <Examples 2 to 8, Comparative Example> In Examples 2 to 8, adhesive compositions C2 to C8 were used respectively, and in the comparative example, an adhesive sheet of Examples 2 to 8 and the comparative example was obtained by the same method as in Example 1 except that the adhesive composition C9 was used. The adhesive sheet of Example 7 formed from the adhesive composition C7 was heat-dried after the adhesive sheet was formed.

[0171] In the pressure-sensitive adhesive sheets of Examples 6 and 7 formed from pressure-sensitive adhesive compositions C6 and C7, respectively, most of the radical scavenger (PEA) in the pressure-sensitive adhesive compositions C6 and C7 was incorporated into the polymer (see the “monomer” column of the pressure-sensitive adhesive compositions “C6” and “C7” in Table 3). In the pressure-sensitive adhesive sheets of Examples 6 and 7, the radical scavenger (PEA) incorporated into the polymer was 20 parts by weight out of 100 parts by weight of the monomer group. In the pressure-sensitive adhesive sheet of Example 6, a part of the radical scavenger (PEA) in the pressure-sensitive adhesive composition C6 was contained in the pressure-sensitive adhesive sheet as an additive separate from the polymer without being incorporated into the polymer (see the “radical scavenger” column of the pressure-sensitive adhesive composition “C6” in Table 3). In the pressure-sensitive adhesive sheet of Example 6, the radical scavenger (PEA) contained in the pressure-sensitive adhesive sheet as an additive was 0.09 part by weight with respect to 100 parts by weight of the monomer group. On the other hand, in the pressure-sensitive adhesive sheet of Example 7, a part of the radical scavenger not incorporated into the polymer was removed from the pressure-sensitive adhesive sheet by volatilizing it by the above-mentioned heat drying so as not to be contained in the pressure-sensitive adhesive sheet as an additive separate from the polymer. Therefore, in the pressure-sensitive adhesive sheet of Example 7, the radical scavenger (PEA) was not contained in the pressure-sensitive adhesive sheet as an additive (see the “radical scavenger” column of the pressure-sensitive adhesive composition “C7” in Table 3).

[0172] [Gel fraction] The gel fractions of the pressure-sensitive adhesive sheets of the examples and comparative examples were measured by the above method. For each pressure-sensitive adhesive sheet, the gel fraction was measured twice: (1) immediately after preparing the pressure-sensitive adhesive sheet and (2) after leaving it in an environment of 105 °C for 24 hours. Table 4 shows the measurement results of the gel fractions of each pressure-sensitive adhesive sheet.

[0173] [Reliability test] The following high-temperature storage test (hereinafter referred to as “105 °C test”) and heat shock test (hereinafter referred to as “HS test”) were performed on each pressure-sensitive adhesive sheet of the examples and comparative examples.

[0174] <Sample preparation for reliability test (105 °C test)> (Production of optical film 2E) A polyvinyl alcohol film was stretched up to 3 times while being dyed in an iodine solution at a temperature of 30°C and a concentration of 0.3 wt% for 1 minute between rolls with different speed ratios. Next, it was stretched while being immersed in an aqueous solution at a temperature of 60°C containing 4 wt% boric acid and 10 wt% potassium iodide for 0.5 minute until the total stretching ratio reached 6 times. Next, after being immersed in an aqueous solution at a temperature of 30°C containing 1.5 wt% potassium iodide for 10 seconds for washing, it was dried at 50°C for 4 minutes to obtain a polarizer (reference numeral 22E in Fig. 8) with a thickness of 18 μm. A transparent protective film (reference numeral 21E in Fig. 8) with a thickness of 30 μm made of a modified acrylic polymer having a lactone ring structure was bonded to one side of the polarizer with a polyvinyl alcohol-based adhesive. Further, a transparent protective film (reference numeral 23E in Fig. 8) with a thickness of 47 μm having a hard coat layer (HC) formed on a triacetyl cellulose film (manufactured by Konica Minolta, trade name "KC4UY") was bonded to the other side of the polarizer with a polyvinyl alcohol-based adhesive. Then, by heating and drying in an oven set at 70°C for 5 minutes, an optical film 2E composed of the transparent protective film 21E, the polarizer 22E, and the transparent protective film 23E was produced as shown in Fig. 8. Further, the surface of the optical film 2E on the transparent protective film 21E side made of a modified acrylic polymer was subjected to corona treatment at a discharge amount of 63 W / m 2 ·min.

[0175] (Production of optical laminate 30E) An optical laminate 30E was produced by disposing the above-described optical film 2E on the exposed surface of each adhesive sheet 1 produced in the examples and comparative examples. Note that the optical film 2E was disposed such that the surface on the transparent protective film 21E side made of a modified acrylic polymer was in contact with the adhesive sheet 1.

[0176] <Reliability test (105°C test)> The reliability of the fabricated optical laminate 30E was evaluated by the following 105°C test. First, the optical laminate 30E was cut into a strip shape with a length of 300 mm and a width of 220 mm to obtain a test piece. Next, the test piece was attached to the surface of non-alkali glass (manufactured by Corning Inc., product name "EG-XG") with a thickness of 0.7 mm using an adhesive sheet 1. The attachment of the test piece to the non-alkali glass was performed using a laminator. After attaching the test piece, it was placed in an autoclave at 50°C and 0.5 MPa for 15 minutes to homogenize the bonding between the non-alkali glass and the adhesive sheet 1, and the adhesive sheet 1 was adhered tightly to the non-alkali glass. Next, the test piece was heat-treated at 105°C for 500 hours under atmospheric pressure. The vicinity of the end of the test piece was observed with an optical microscope to confirm the presence or absence of peeling from the end of the test piece and foaming in the vicinity of the end. A: No peeling and foaming that affect image display are confirmed. B: There is slight foaming at the end, but it is not at a level that affects image display. C: There are multiple bubbles at the end, but it is not at a level that affects image display. D: There is peeling and / or foaming that affect image display. Table 4 shows the evaluation results of the reliability of each adhesive sheet by the 105°C test.

[0177] <Sample preparation for reliability test (HS test)> (Optical film 2D) As a sample for the HS test, first, the optical film 2D shown in Fig. 6 was fabricated.

[0178] (Polarizer 23D) The polarizer 23D that constitutes the optical film 2D was produced as follows. First, an amorphous isophthalic copolyethylene terephthalate film (thickness: 100 μm) in a long strip shape with a Tg of about 75 °C was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to corona treatment. 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin in which polyvinyl alcohol (degree of polymerization 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosefimer") were mixed at a ratio of 9:1, and the mixture was dissolved in water to prepare a PVA aqueous solution (coating solution). The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60 °C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.

[0179] The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130 °C (air-assisted stretching treatment). Next, the laminate after the air-assisted stretching treatment was immersed in an insolubilization bath at a liquid temperature of 40 °C for 30 seconds (insolubilization treatment). The insolubilization bath is a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water. Next, it was immersed in a dyeing bath at a liquid temperature of 30 °C for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer became a desired value (dyeing treatment). The dyeing bath is an iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water.

[0180] Next, it was immersed in a cross-linking bath at a liquid temperature of 40 °C for 30 seconds (cross-linking treatment). The cross-linking bath is a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water. Thereafter, while immersing the laminate in a boric acid aqueous solution at a liquid temperature of 70 °C, uniaxial stretching was performed in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds so that the total stretching ratio became 5.5 times (in-water stretching treatment). The boric acid aqueous solution is an aqueous solution containing a boric acid concentration of 4% by weight and a potassium iodide concentration of 5% by weight.

[0181] Thereafter, the laminate was immersed in a washing bath at a liquid temperature of 20°C (washing treatment). The washing bath is an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water. Thereafter, while drying in an oven maintained at about 90°C, it was brought into contact with a SUS heating roll whose surface temperature was maintained at about 75°C (dry shrinkage treatment).

[0182] In this way, a polarizer 23D with a thickness of about 5 μm was formed on the resin substrate.

[0183] (First retardation film 21D) The first retardation film 21D that constitutes the optical film 2D was produced as follows. 48 parts by weight of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Methocel 60SH-50), 15601 parts by weight of distilled water, 8161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate, and 45 parts by weight of t-butylperoxy pivalate as a polymerization initiator were placed in an autoclave equipped with a stirrer, a cooling pipe, a nitrogen introduction pipe, and a thermometer. After performing nitrogen bubbling for 1 hour, radical suspension polymerization was carried out by holding at 49°C for 24 hours while stirring. Next, it was cooled to room temperature, and the suspension containing the produced polymer particles was centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure to obtain a white fumarate resin.

[0184] The obtained fumarate resin was dissolved in methyl ethyl ketone to form a solution with a solid content concentration of 20% by weight. Further, 5 parts by weight of tributyl trimellitate was added as a plasticizer with respect to 100 parts by weight of the fumarate resin to prepare a dope.

[0185] As the support film, a polyester film with a thickness of 75 μm (biaxially stretched film of polyethylene terephthalate / isophthalate copolymer) was used. The above dope was applied and dried so that the film thickness after drying was about 6 μm, and a laminate A in which a coating film of a fumarate resin was closely laminated on the support was obtained. By uniaxially stretching the free end of the above laminate A, a first retardation film 21D (positive B plate) having a refractive index anisotropy of nz > nx > ny was obtained on the support.

[0186] (Second retardation film 22D) As the second retardation film 22D constituting the optical film 2D, a cyclic olefin-based film (positive C plate; manufactured by Nippon Zeon Co., Ltd., trade name "Zeonoa Film ZT12-50135") having a refractive index anisotropy of nz > nx = ny was used.

[0187] Thereafter, the second retardation film 22D was bonded onto the first retardation film 21D via an ultraviolet curable adhesive to obtain a laminate B. Thereafter, by peeling the support from the laminate B, a laminate C of the first retardation film 21D and the second retardation film 22D was obtained.

[0188] (Transparent protective film 24D) As the transparent protective film 24D constituting the optical film 2D, an acrylic resin film having a glutarimide structure (manufactured by Kaneka Corporation, trade name "HTX") was used. The thickness of the transparent protective film 24D was 40 μm.

[0189] These films 21D to 24D were laminated in the order of the laminate C (the first retardation film 21D and the second retardation film 22D), the polarizer 23D, and the transparent protective film 24D to produce the optical film 2D. The laminate C and the polarizer 23D were bonded via an ultraviolet curable adhesive so that the second retardation film 22D and the polarizer 23D faced each other. The polarizer 23D and the transparent protective film 24D were similarly bonded via an ultraviolet curable adhesive.

[0190] <Fabrication of Optical Laminated Film> Furthermore, a transparent protective film and an antireflection film were prepared. As the transparent protective film, an acrylic resin film having a glutarimide structure (transparent protective film) (manufactured by Kaneka Corporation, trade name "HTX") was used. The thickness of the transparent protective film was 40 μm. As the antireflection film, an antireflection film manufactured by Decelials Co., Ltd. (total thickness of the antireflection layer and the hard coat layer: 4 μm, substrate thickness: 80 μm) was used. Then, the transparent protective film and the antireflection film were laminated in this order on the transparent protective film 24D (see Fig. 6) side of the optical film 2D to fabricate an optical laminated film. The optical film 2D and the transparent protective film were bonded to each other with a photocurable adhesive sheet corresponding to each example and comparative example. The thickness of this adhesive sheet was 12 μm. The transparent protective film and the antireflection film were bonded to each other with a photocurable adhesive sheet corresponding to each example and comparative example. The thickness of this adhesive sheet was 12 μm.

[0191] <Fabrication of Optical Laminate> An optical laminate was fabricated by disposing the above-described optical laminated film on the exposed surface of each adhesive sheet 1 (see Fig. 6) fabricated in the examples and comparative examples. Note that the optical laminated film was disposed such that the surface on the optical film 2D side (the first retardation film 21D side) was in contact with the adhesive sheet 1 (see Fig. 6).

[0192] <Reliability Test (HS Test)> The reliability of the fabricated optical laminate was evaluated by the following HS test. First, the optical laminate was cut into strips measuring 300 mm in length and 220 mm in width to obtain test pieces. Next, the test pieces were attached to the surface of non-alkali glass (manufactured by Corning Inc., product name "EG-XG") with a thickness of 0.7 mm using an adhesive sheet 1 (see Fig. 6). The attachment of the test pieces to the non-alkali glass was performed using a laminator. After attaching the test pieces, they were placed in an autoclave at 50 °C and 0.5 MPa for 15 minutes to homogenize the bonding between the non-alkali glass and the adhesive sheet 1, and the adhesive sheet 1 was made to adhere tightly to the non-alkali glass. Next, a cycle test was performed on the test pieces for 200 cycles with one cycle consisting of holding at a low temperature (-40 °C) and a high temperature (85 °C). Specifically, in one cycle, the test pieces were first held at -40 °C for 30 minutes, then heated to reach 85 °C in 2 to 5 minutes, then held at 85 °C for 30 minutes, and then cooled to reach -40 °C in 2 to 5 minutes. After 200 cycles, the vicinity of the ends of the test pieces was observed with an optical microscope, and the presence or absence of peeling from the ends of the test pieces and foaming in the vicinity of the ends was confirmed in the same manner as in the above 105 °C test. A: No peeling or foaming that affects image display was confirmed. B: There is slight foaming at the ends, but it is not at a level that affects image display. C: There are multiple bubbles at the ends, but it is not at a level that affects image display. D: There is peeling and / or foaming that affects image display. Table 4 shows the evaluation results of the reliability of each adhesive sheet by the HS test.

[0193]

Table 4

[0194] As shown in Table 4, it can be seen that for the pressure-sensitive adhesive sheets of the examples, the absolute value of the difference in the gel fraction before and after standing for 24 hours in an environment of 105°C is smaller than that of the pressure-sensitive adhesive sheets of the comparative examples. Also, each pressure-sensitive adhesive sheet of the examples is evaluated as A in the 105°C test, and it can be seen that the state after the 105°C test is better than that of the pressure-sensitive adhesive sheets of the comparative examples. Furthermore, each pressure-sensitive adhesive sheet of the examples is evaluated as C or higher in the HS test, and it can be seen that peeling and foaming at a level that affects image display do not occur. From these facts, it was confirmed that each pressure-sensitive adhesive sheet of the examples has improved durability under further high temperatures such as 100°C or higher and is less likely to have reduced durability in the heat shock test.

Industrial Applicability

[0195] The pressure-sensitive adhesive composition of the present invention can be used in pressure-sensitive adhesive sheets, optical laminated bodies, and image display devices.

Explanation of Reference Numerals

[0196] 1 Pressure-sensitive adhesive sheet 2, 2A, 2B, 2D, 2E Optical film 30, 30A to 30E Optical laminated body 50 Image display device

Claims

1. A photocurable pressure-sensitive adhesive composition comprising at least one selected from the group consisting of a monomer group and a partial polymer of the monomer group, wherein the monomer group contains a nitrogen atom-containing monomer, and the pressure-sensitive adhesive composition contains a radical scavenger. A photocurable pressure-sensitive adhesive composition.

2. The photocurable pressure-sensitive adhesive composition according to claim 1, wherein the radical scavenger has a polymerizable unsaturated double bond and corresponds to a part of the monomers constituting the monomer group.

3. The photocurable pressure-sensitive adhesive composition according to claim 1, wherein the radical scavenger does not have a polymerizable unsaturated double bond.

4. The photocurable pressure-sensitive adhesive composition according to claim 1, wherein the radical scavenger contains at least one selected from the group consisting of a phenoxy-based radical scavenger, an amine-based radical scavenger, and a phosphite-based radical scavenger.

5. The photocurable pressure-sensitive adhesive composition according to claim 4, wherein the radical scavenger contains at least one of a phenoxy-based radical scavenger and a phosphite-based radical scavenger.

6. The photocurable pressure-sensitive adhesive composition according to claim 5, wherein the radical scavenger has a phenoxy structure.

7. The photocurable pressure-sensitive adhesive composition according to claim 1, wherein the content of the solvent in the pressure-sensitive adhesive composition is 5% by weight or less.

8. The photocurable pressure-sensitive adhesive composition according to claim 2, wherein the content of the radical scavenger in the pressure-sensitive adhesive composition is 30 parts by weight or less per 100 parts by weight of the monomer group. The photocurable pressure-sensitive adhesive composition according to claim 2.

9. The photocurable pressure-sensitive adhesive composition according to claim 3, wherein the content of the radical scavenger in the pressure-sensitive adhesive composition is 5 parts by weight or less with respect to 100 parts by weight of the monomer group. The photocurable pressure-sensitive adhesive composition according to claim 3.

10. The photocurable pressure-sensitive adhesive composition according to claim 1, wherein the monomer group contains a (meth)acrylic monomer.

11. A pressure-sensitive adhesive sheet formed from the photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 10.

12. The pressure-sensitive adhesive sheet according to claim 11, wherein in a test of leaving it standing for 24 hours in an environment of 105°C, the absolute value |Ga - Gb| of the difference between the gel fraction Ga before the test and the gel fraction Gb after the test is 10% or less.

13. An optical laminate comprising the pressure-sensitive adhesive sheet according to claim 11, and an optical film.

14. An image display device comprising the optical laminate according to claim 13.

Images