Photocurable resin composition, pressure sensitive adhesive sheet, and method for producing laminate

Abstract

To provide a photocurable resin composition excellent in printability, photocurability in the presence of oxygen, adhesiveness, resistance and light-shielding property.SOLUTION: A photocurable resin composition comprising a monofunctional (meth) acrylic monomer, a polyfunctional (meth) acrylic monomer, a photopolymerization initiator, a thermoplastic resin, and a colorant, wherein a content of the polyfunctional (meth) acrylic monomer in 100 parts by mass of a total content of the monofunctional (meth) acrylic monomer and the polyfunctional (meth) acrylic monomer is 0.1 parts by mass or more and 30 parts by mass or less, A content of the photopolymerization initiator is 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of a total content of the monofunctional (meth) acrylic monomer and the polyfunctional (meth) acrylic monomer, the thermoplastic resin has a block structure or a graft structure, and a content ratio of the thermoplastic resin in the photocurable resin composition is 5% by mass or more and 60% by mass or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocurable resin composition. The present invention also relates to a pressure-sensitive adhesive sheet using the photocurable resin composition, and a method for producing a laminate using the photocurable resin composition. [Background technology]

[0002] Adhesives are typically used to bond electronic components inside electronic devices such as smartphones and PCs. In a typical adhesive bonding method, a pressure-sensitive adhesive sheet is first prepared with separators on both sides of the adhesive, and then the adhesive sheet is cut to the desired shape. One separator is then peeled off from the cut adhesive sheet, and one side of the exposed adhesive is bonded to an adherend. The other separator is then peeled off, and the other side of the exposed adhesive is bonded to another adherend. With this method, a portion of the adhesive sheet is discarded as waste after cutting.

[0003] In response to this, a method has been investigated in which a pressure-sensitive adhesive composition is printed in a desired shape and then attached to an adherend, which can reduce the generation of waste. As an invention relating to an adhesive composition that can be used in such a method, for example, Patent Document 1 discloses an invention for providing a radiation-curable adhesive composition that allows for fine patterning and exhibits high adhesion to various adherends such as metals and plastics. Patent Document 1 describes a radiation-curable adhesive composition that contains 10 to 70% by weight of an aromatic ring-free ethylenically unsaturated monomer, 1 to 10% by weight of a photopolymerization initiator, and 10 to 55% by weight of a crosslinking agent. Patent Document 2 discloses an invention for providing a photocurable adhesive composition that, even when irradiated with light in the presence of oxygen, gives a laminate having adhesive strength equivalent to that in the absence of oxygen. Patent Document 2 describes a photocurable adhesive composition that contains (A) a (meth)acrylate oligomer, (B) a monofunctional (meth)acrylic monomer, (C) a difunctional to tetrafunctional (meth)acrylic monomer, (D) a photoinitiator, (E) a tackifier having a softening point of 70 to 150°C, and (F) a liquid plasticizer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-216742 [Patent Document 2] International Publication No. 2016 / 163152 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the method of printing a pressure-sensitive adhesive composition into a desired shape and then laminating it to an adherend can reduce waste generation. Meanwhile, light irradiation is a desirable method for curing a pressure-sensitive adhesive composition to avoid heating the adherend. However, if the pressure-sensitive adhesive composition is not covered with a separator and exposed to an atmospheric environment, i.e., in the presence of oxygen, during curing, oxygen inhibition can prevent the outermost surface from curing, resulting in insufficient adhesive strength. Therefore, to prevent oxygen inhibition, it was necessary to seal the pressure-sensitive adhesive composition with a separator and irradiate it with light in an inert gas atmosphere to promote the reaction. Furthermore, even when adhesive strength was improved using a material less susceptible to oxygen inhibition, creep resistance could be reduced. Furthermore, many of the conventional pressure-sensitive adhesive compositions used in the above-mentioned methods have high transparency, making them difficult to adapt to applications requiring light-blocking properties. Therefore, there has been a demand for a photocurable resin composition that is excellent in all of printability, photocurability in the presence of oxygen, adhesiveness, creep resistance, and light-blocking properties.

[0006] An object of the present invention is to provide a photocurable resin composition that is excellent in printability, photocurability in the presence of oxygen, adhesiveness, creep resistance, and light-shielding properties. Another object of the present invention is to provide a pressure-sensitive adhesive sheet using the photocurable resin composition, and a method for producing a laminate using the photocurable resin composition. [Means for solving the problem]

[0007] Disclosure 1 relates to a photocurable resin composition containing a monofunctional (meth)acrylic monomer, a polyfunctional (meth)acrylic monomer, a photopolymerization initiator, a thermoplastic resin, and a colorant, wherein the content of the polyfunctional (meth)acrylic monomer is 0.1 parts by mass or more and 30 parts by mass or less in 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer, and the content of the photopolymerization initiator relative to 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer is 0.1 parts by mass or more and 30 parts by mass or less. the amount of the thermoplastic resin is 0.5 parts by mass or more and 10 parts by mass or less, the thermoplastic resin has a block structure or a graft structure, the content of the thermoplastic resin in the photocurable resin composition is 5% by mass or more and 60% by mass or less, the viscosity of the photocurable resin composition measured using an E-type viscometer at 25°C and 10 rpm is 0.1 Pa s or more and 100 Pa s or less, the photocurable resin composition is coated on a substrate to a thickness of 50 μm, and the coated surface is not sealed, and the coated surface is irradiated with light at a wavelength of 315 nm or more and 480 nm or less at an illuminance of 500 mW / cm in an atmospheric environment. 2 The light is irradiated at 3000mJ / cm 2 The photocurable resin composition is a photocurable resin composition in which a reaction rate of a cured product obtained by irradiating the photocurable resin composition so as to satisfy the above condition is 90% or more, the cured product has a gel fraction of 10% by mass or more and 80% by mass or less, and the cured product of the photocurable resin composition having a thickness of 1.0 mm has an optical density of 2.0 or more. Disclosure 2 is the photocurable resin composition of Disclosure 1, wherein the colorant is titanium black or zirconium nitride. Disclosure 3 is the photocurable resin composition of Disclosure 1 or 2, wherein the thermoplastic resin contains a thermoplastic resin having a structure derived from styrene. Disclosure 4 relates to the photocurable resin composition of Disclosure 3, wherein the thermoplastic resin having a structure derived from styrene is a (meth)acrylic / styrene copolymer. Disclosure 5 is the photocurable resin composition of Disclosure 3 or 4, in which the content of the styrene-derived structure in the thermoplastic resin having the styrene-derived structure is 5% by mass or more. Disclosure 6 is the photocurable resin composition of Disclosures 1, 2, 3, 4, or 5, wherein the thermoplastic resin contains a triblock copolymer, and the content of the triblock copolymer in the thermoplastic resin is 50 mass % or more. Disclosure 7 is the photocurable resin composition of Disclosures 1, 2, 3, 4, 5, or 6, wherein the thermoplastic resin has a weight-average molecular weight of 100,000 or more and 500,000 or less. Disclosure 8 is the photocurable resin composition of Disclosures 1, 2, 3, 4, 5, 6, or 7, wherein the photopolymerization initiator has a weight average molecular weight of 500 or more. Disclosure 9 is the photocurable resin composition of Disclosure 1, 2, 3, 4, 5, 6, 7, or 8, wherein the photopolymerization initiator has two or more carbonyl groups that contribute to a Norrish type I cleavage reaction in one molecule. Disclosure 10 is the photocurable resin composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, or 9, further comprising an antifoaming agent. Disclosure 11 is the photocurable resin composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, further containing an inorganic filler. Disclosure 12 is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a cured product of the photocurable resin composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11. Disclosure 13 is the pressure-sensitive adhesive sheet of Disclosure 12, which has a substrate and a pressure-sensitive adhesive layer containing a cured product of the photocurable resin composition on at least one surface of the substrate. The present disclosure 14 is a method for producing a laminate, comprising the steps of printing the photocurable resin composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, and attaching an adherend using the printed photocurable resin composition. Disclosure 15 is the method for producing a laminate according to Disclosure 14, wherein the method for printing the photocurable resin composition is screen printing, inkjet printing, or flexographic printing. The present invention will be described in detail below.

[0008] The present inventors have investigated the possibility of adjusting the viscosity, reactivity, gel fraction, and optical density of a photocurable resin composition containing a monofunctional (meth)acrylic monomer, a polyfunctional (meth)acrylic monomer, a photopolymerization initiator, and a thermoplastic resin having a specific structure in specific ranges of content, and further containing a colorant. As a result, they have found that a photocurable resin composition can be obtained that is excellent in printability, photocurability in the presence of oxygen, adhesiveness, creep resistance, and light-blocking properties, and have completed the present invention.

[0009] The photocurable resin composition of the present invention contains a monofunctional (meth)acrylic monomer. The monofunctional (meth)acrylic monomer is a polymerizable monomer that is polymerized by a reaction with a photopolymerization initiator described below. By containing the monofunctional (meth)acrylic monomer, the photocurable resin composition of the present invention has excellent adhesion to various substrates. In this specification, the term "(meth)acrylic" refers to acrylic or methacrylic, the term "(meth)acrylic monomer" refers to a monomer having a (meth)acryloyl group, and the term "(meth)acryloyl" refers to acryloyl or methacryloyl. In addition, in this specification, the term "monofunctional (meth)acrylic monomer" refers to a monomer having one (meth)acryloyl group in one molecule.

[0010] Examples of the monofunctional (meth)acrylic monomer include a monofunctional (meth)acrylic acid ester compound, a monofunctional (meth)acrylamide compound, and a monofunctional (meth)acrylimide compound.

[0011] Examples of the monofunctional (meth)acrylic acid ester compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-heptyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. , cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, bicyclopentenyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, tetrahydrofurfuryl alcohol acrylic acid polymer ester, ethyl carbitol (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-Octafluoropentyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl phosphate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, 2-(((butylamino)carbonyl)oxy)ethyl (meth)acrylate, (3-propyloxetan-3-yl)methyl (meth)acrylate, (3-butyloxetan-3-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)ethyl (meth)acrylate, Examples of the acrylates include (oxetan-3-yl)propyl (meth)acrylate, (3-ethyloxetan-3-yl)butyl (meth)acrylate, (3-ethyloxetan-3-yl)pentyl (meth)acrylate, (3-ethyloxetan-3-yl)hexyl (meth)acrylate, γ-butyrolactone (meth)acrylate, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-2-isobutyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-cyclohexyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, and cyclic trimethylolpropane formal acrylate. In this specification, the term "(meth)acrylate" means acrylate or methacrylate.

[0012] Examples of the monofunctional (meth)acrylamide compound include N,N-dimethyl(meth)acrylamide, N-(meth)acryloylmorpholine, N-hydroxyethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N,N-dimethylaminopropyl(meth)acrylamide.

[0013] Examples of the monofunctional (meth)acrylimide compound include N-(meth)acryloyloxyethylhexahydrophthalimide.

[0014] The preferred lower limit of the content of the monofunctional (meth)acrylic monomer in the photocurable resin composition of the present invention is 20% by mass, and the preferred upper limit is 90% by mass. When the content of the monofunctional (meth)acrylic monomer is within this range, the resulting photocurable resin composition has better adhesion to various substrates. The more preferred lower limit of the content of the monofunctional (meth)acrylic monomer is 30% by mass, and the more preferred upper limit is 85% by mass.

[0015] The photocurable resin composition of the present invention contains a polyfunctional (meth)acrylic monomer. The polyfunctional (meth)acrylic monomer is a polymerizable monomer that is polymerized by the reaction of a photopolymerization initiator described below, and the polyfunctional (meth)acrylic monomer serves as a crosslinking component. In this specification, the term "polyfunctional (meth)acrylic monomer" refers to a monomer having two or more (meth)acryloyl groups in one molecule.

[0016] Examples of the polyfunctional (meth)acrylic monomer include polyfunctional urethane (meth)acrylates, polyfunctional (meth)acrylic acid ester compounds, and polyfunctional epoxy (meth)acrylates. In this specification, the term "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound have been reacted with (meth)acrylic acid.

[0017] The polyfunctional urethane (meth)acrylate can be obtained, for example, by reacting an isocyanate compound with a (meth)acrylic acid derivative having a hydroxyl group in the presence of a catalytic amount of a tin compound.

[0018] Examples of isocyanate compounds that can be used as raw materials for the polyfunctional urethane (meth)acrylate include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanatephenyl)thiophosphate, tetramethylxylylene diisocyanate, and 1,6,11-undecane triisocyanate.

[0019] Furthermore, as the isocyanate compound serving as a raw material for the polyfunctional urethane (meth)acrylate, a chain-extended isocyanate compound obtained by reacting a polyol with an excess of an isocyanate compound can also be used. Examples of the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

[0020] Examples of the (meth)acrylic acid derivative having a hydroxyl group include hydroxyalkyl mono(meth)acrylate, mono(meth)acrylate of a dihydric alcohol, and mono(meth)acrylate or di(meth)acrylate of a trihydric alcohol. Examples of the hydroxyalkyl mono(meth)acrylate include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate. Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of the trihydric alcohol include trimethylolethane, trimethylolpropane, and glycerin.

[0021] Examples of the polyfunctional (meth)acrylic acid ester compound include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-Propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-added bisphenol A di(meth)acrylate, propylene oxide-added bisphenol A di(meth)acrylate, ethylene oxide-added bisphenol F di(meth)acrylate, dimethylol dicyclopentadiene Di(meth)acrylate, ethylene oxide modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, carbonate diol di(meth)acrylate, polyether diol di(meth)acrylate, polyester diol di(meth)acrylate, polycaprolactone diol di(meth)acrylate, polybutadiene diol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, trimethyl Trimethylolpropane tri(meth)acrylate, ethylene oxide-added trimethylolpropane tri(meth)acrylate, propylene oxide-added trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, ethylene oxide-added isocyanuric acid tri(meth)acrylate, glycerin tri(meth)acrylate, propylene oxide-added glycerin tri(meth)acrylate , pentaerythritol tri(meth)acrylate, tris(meth)acryloyloxyethyl phosphate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, etc.

[0022] Examples of the polyfunctional epoxy(meth)acrylate include bisphenol A type epoxy(meth)acrylate, bisphenol F type epoxy(meth)acrylate, bisphenol E type epoxy(meth)acrylate, and caprolactone-modified versions of these.

[0023] The lower limit of the content of the polyfunctional (meth)acrylic monomer in 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer is 0.1 parts by mass, and the upper limit is 30 parts by mass. When the content of the polyfunctional (meth)acrylic monomer in 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer is within this range, the photocurable resin composition of the present invention exhibits excellent adhesion to various substrates and creep resistance. The lower limit of the content of the polyfunctional (meth)acrylic monomer in 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer is preferably 0.2 parts by mass, and the upper limit is preferably 25 parts by mass, more preferably 0.3 parts by mass, and more preferably 20 parts by mass. Furthermore, the preferred lower limit of the content of the polyfunctional (meth)acrylic monomer in the photocurable resin composition of the present invention is 0.1% by mass, and the preferred upper limit is 20% by mass. When the content of the polyfunctional (meth)acrylic monomer in the photocurable resin composition of the present invention is within this range, the resulting photocurable resin composition will have better adhesion to various substrates and creep resistance. The more preferred lower limit of the content of the polyfunctional (meth)acrylic monomer in the photocurable resin composition of the present invention is 0.2% by mass, and the more preferred upper limit is 15% by mass.

[0024] The photocurable resin composition of the present invention preferably contains a compound having a cyclic structure containing a nitrogen atom (hereinafter also referred to as a "nitrogen-containing cyclic compound") as a polymerizable monomer. By containing the nitrogen-containing cyclic compound, the resulting photocurable resin composition has better photocurability in the presence of oxygen. The nitrogen-containing cyclic compound may be one contained in the monofunctional (meth)acrylic monomer or the polyfunctional (meth)acrylic monomer, or may not be one contained in the monofunctional (meth)acrylic monomer or the polyfunctional (meth)acrylic monomer.

[0025] The nitrogen-containing cyclic compound preferably contains at least one selected from the group consisting of monofunctional radically polymerizable monomers having a lactam structure and maleimide derivatives, and more preferably contains a maleimide derivative.

[0026] Among the above maleimide derivatives, examples of monofunctional maleimides include N-cyclohexylmaleimide, N-laurylmaleimide, 4-hydroxyphenylmaleimide, N-(4-carboxycyclohexylmethyl)maleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-(2-chlorophenyl)maleimide, N-methylmaleimide, and N-ethylmaleimide. Examples of suitable maleimide include N-isopropylmaleimide, N-butylmaleimide, N-benzylmaleimide, N-phenylmethylmaleimide, N-(2,4,6-tribromophenyl)maleimide, N-(3-(triethoxysilyl)propyl)maleimide, N-octadecenylmaleimide, N-dodecenylmaleimide, N-(2-methoxyphenyl)maleimide, N-(2,4,6-trichlorophenyl)maleimide, and N-(1-hydroxyphenyl)maleimide. Among these, it is desirable to select a maleimide derivative that does not have a structure in which hydrogen is bonded to a heteroatom from the viewpoint of increasing the reaction rate. Furthermore, from the viewpoint of improving adhesive strength, a maleimide derivative that has a structure in which hydrogen is bonded to a heteroatom may also be used. Specifically, the monofunctional maleimide is preferably at least one selected from the group consisting of N-cyclohexylmaleimide, 4-hydroxyphenylmaleimide, and N-(4-carboxycyclohexylmethyl)maleimide, and more preferably N-cyclohexylmaleimide. Furthermore, examples of the polyfunctional maleimides among the maleimide derivatives include N,N'-methylene bismaleimide, N,N'-trimethylene bismaleimide, N,N'-dodecamethylene bismaleimide, N,N'-(4,4'-diphenylmethane) bismaleimide, 1,4-dimaleimidecyclohexane, isophorone bisurethane bis(N-ethylmaleimide), N,N'-p-phenylene bismaleimide, N,N'-m-phenylene bismaleimide, N,N'-m-toluylene bismaleimide, and N,N'-4,4'-biphenyl Examples of suitable maleimide derivatives include N,N'-4,4'-(3,3'-dimethyl-biphenylene)bismaleimide, N,N'-4,4'-(3,3'-dimethyldiphenylmethane)bismaleimide, N,N'-4,4'-(3,3'-diethyldiphenylmethane)bismaleimide, N,N'-4,4'-diphenylpropane bismaleimide, N,N'-4,4'-diphenylether bismaleimide, N,N'-3,3'-diphenylsulfone bismaleimide, and N,N'-4,4'-diphenylsulfone bismaleimide. From the viewpoint of increasing the reaction rate, the above-mentioned monofunctional maleimide may be used in combination with these polyfunctional maleimides as the maleimide derivative, but using a large amount of polyfunctional maleimide in combination is not preferred because the gel fraction increases.

[0027] The monofunctional radically polymerizable monomer having a lactam structure is preferably a compound represented by the following formula (1).

[0028] [ka]

[0029] In formula (1), n ​​represents an integer of 2 to 6.

[0030] Examples of the compound represented by the above formula (1) include N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, etc. Among these, N-vinyl-ε-caprolactam is preferred.

[0031] The preferred lower limit of the content of the nitrogen-containing cyclic compound in the photocurable resin composition of the present invention is 0.1% by mass, and the preferred upper limit is 30% by mass. When the content of the nitrogen-containing cyclic compound is within this range, the resulting pressure-sensitive adhesive sheet has better surface curability and adhesion to various substrates. The more preferred lower limit of the content of the nitrogen-containing cyclic compound is 0.5% by mass, and the more preferred upper limit is 25% by mass.

[0032] The photocurable resin composition of the present invention contains a photopolymerization initiator. The preferred lower limit of the weight-average molecular weight of the photopolymerization initiator is 500. By using a photopolymerization initiator having a weight-average molecular weight of 500 or more, it becomes easy to adjust the reactivity and gel fraction of the cured product of the obtained photocurable resin composition to the ranges described below, and as a result, the photocurability, adhesiveness, and creep resistance in the presence of oxygen become superior. The more preferred lower limit of the weight-average molecular weight of the photopolymerization initiator is 800, even more preferred is 1000, and particularly preferred is 1100. From the viewpoint of solubility and ease of handling, the upper limit of the weight average molecular weight of the photopolymerization initiator is preferably 10,000, and more preferably 5,000. In this specification, the "weight average molecular weight" can be determined by measuring the molecular weight distribution in terms of polystyrene using, for example, gel permeation chromatography (GPC). Specifically, it can be determined by, for example, measuring using gel permeation chromatography (Waters, "2690 Separations Module" or the like) under the following conditions: Solvent: tetrahydrofuran Sample flow rate: 1 mL / min Detector: Differential refractive index RI Column: GPC KF-806L (Showa Denko) Column temperature (measurement temperature): 40°C Injection volume: 20μL

[0033] The photopolymerization initiator is preferably a Norrish I type photopolymerization initiator. By using the Norrish I type photopolymerization initiator, it becomes easier to adjust the reaction rate and gel fraction of the cured product of the photocurable resin composition of the present invention to the ranges described below. In particular, the photopolymerization initiator preferably has two or more carbonyl groups per molecule that contribute to the Norrish I type cleavage reaction.

[0034] Examples of the Norrish type I photopolymerization initiator include polymers of ethyl (2,4,6-trimethylbenzoyl)-phenylphosphonate, polyethylene glycol di(β-4(4-(2-dimethylamino-2-benzyl)butanoylphenyl)piperazine)propionate, bis(benzophenone-2-carboxylic acid) polyethylene glycol ester, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone.

[0035] Among the above Norrish type I photopolymerization initiators, commercially available ones include, for example, Omnipol TP, Omnipol 910, Omnirad TPO, and Omnirad 369 (all manufactured by IGM Resins).

[0036] The lower limit of the content of the photopolymerization initiator relative to 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer is 0.5 parts by mass, and the upper limit is 10 parts by mass. When the content of the photopolymerization initiator is within this range relative to 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer, the photocurable resin composition of the present invention exhibits excellent storage stability, photocurability, and adhesion to various substrates. The lower limit of the content of the photopolymerization initiator relative to 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer is preferably 0.7 parts by mass, and the upper limit is preferably 9 parts by mass, more preferably 0.9 parts by mass, and more preferably 8 parts by mass. Furthermore, the preferred lower limit of the content of the photopolymerization initiator in the photocurable resin composition of the present invention is 0.5% by mass, and the preferred upper limit is 8% by mass. When the content of the photopolymerization initiator in the photocurable resin composition of the present invention is within this range, the resulting photocurable resin composition becomes more excellent in storage stability, photocurability, and adhesion to various substrates. The more preferred lower limit of the content of the photopolymerization initiator in the photocurable resin composition of the present invention is 0.7% by mass, and the more preferred upper limit is 7% by mass.

[0037] The photocurable resin composition of the present invention contains a thermoplastic resin. The thermoplastic resin has a block structure or a graft structure. By containing a thermoplastic resin having the above-mentioned block structure or graft structure, the photocurable resin composition of the present invention has excellent creep resistance. In particular, the thermoplastic resin preferably has a block structure. The block structure or graft structure may be present in any part of the molecule of the thermoplastic resin, and a random structure may be present in other parts. Even if the thermoplastic resin is a polymer of two or more monomers having a common structure, if the two or more monomers are different compounds and the polymer has a block structure or a graft structure, it is treated as a thermoplastic resin having a block structure or a graft structure. An example of such a polymer is an acrylic triblock copolymer derived from three types of acrylic monomers.

[0038] The thermoplastic resin preferably contains a thermoplastic resin having a structure derived from styrene or a thermoplastic resin having a structure derived from a (meth)acrylic compound. By containing the thermoplastic resin having a structure derived from styrene or a thermoplastic resin having a structure derived from a (meth)acrylic compound, the resulting photocurable resin composition has better creep resistance. In particular, the thermoplastic resin more preferably contains a thermoplastic resin having a structure derived from styrene.

[0039] Examples of the thermoplastic resin having a structure derived from styrene include (meth)acrylic / styrene copolymer, acrylonitrile / styrene / (meth)acrylic copolymer, butadiene / styrene copolymer, isoprene / styrene copolymer, ethylene-butylene / styrene copolymer, ethylene-propylene / styrene copolymer, etc. Among them, (meth)acrylic / styrene copolymer is preferred from the viewpoints of compatibility with the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer and improvement of creep resistance.

[0040] The preferred lower limit of the content of the styrene-derived structure in the thermoplastic resin having the styrene-derived structure is 5% by mass. When the content of the styrene-derived structure is 5% by mass or more, the resulting photocurable resin composition has better creep resistance. The more preferred lower limit of the content of the styrene-derived structure is 6% by mass. Furthermore, from the viewpoints of compatibility with the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer and adhesion to various substrates, the upper limit of the content of the styrene-derived structure in the thermoplastic resin having a styrene-derived structure is preferably 40 mass %, more preferably 30 mass %.

[0041] Examples of the thermoplastic resin having a structure derived from the (meth)acrylic compound include poly(meth)acrylate, acrylonitrile / styrene / (meth)acrylic copolymer, (meth)acrylic / styrene copolymer, ethylene / (meth)acrylic copolymer, etc. Among these, (meth)acrylic / styrene copolymer is preferred from the viewpoints of compatibility with the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer and improvement of creep resistance.

[0042] The thermoplastic resin preferably contains a triblock copolymer. By including the thermoplastic resin that is a triblock copolymer, the resulting photocurable resin composition has better creep resistance. In particular, the thermoplastic resin more preferably contains a (meth)acrylic / styrene triblock copolymer as the ABA triblock copolymer.

[0043] The preferred lower limit of the content of the triblock copolymer in the thermoplastic resin is 50% by mass. When the content of the triblock copolymer is 50% by mass or more, the resulting photocurable resin composition has better creep resistance. The more preferred lower limit of the content of the triblock copolymer is 70% by mass. The content of the triblock copolymer may be 100% by mass, that is, the thermoplastic resin may contain only the triblock copolymer.

[0044] The thermoplastic resin preferably has a weight-average molecular weight of 100,000 (lower limit) and 500,000 (upper limit). The thermoplastic resin having a weight-average molecular weight within this range provides the resulting photocurable resin composition with superior creep resistance. The thermoplastic resin more preferably has a weight-average molecular weight of 150,000 (lower limit) and 400,000 (upper limit).

[0045] The lower limit of the content of the thermoplastic resin in the photocurable resin composition of the present invention is 5% by mass, and the preferred upper limit is 60% by mass. By having the content of the thermoplastic resin in this range, the resulting photocurable resin composition will have better creep resistance. The more preferred lower limit of the content of the thermoplastic resin is 10% by mass, and the more preferred upper limit is 40% by mass.

[0046] The photocurable resin composition of the present invention contains a colorant. By containing the colorant, the optical density of the photocurable resin composition of the present invention can be easily adjusted to the range described below, and the photocurable resin composition has excellent light-blocking properties.

[0047] The colorant may be a pigment or a dye. Specific examples of the colorant include titanium black, zirconium nitride, carbon black, iron oxide, aniline black, and cyanine black. Among these, from the viewpoint of increasing the optical density of the resulting photocurable resin composition and improving the light-shielding properties, the colorant is preferably a pigment, and more preferably titanium black or zirconium nitride.

[0048] The titanium black and zirconium nitride are pigments with low light transmittance in the visible light region and high light transmittance in the ultraviolet region or vicinity. That is, the titanium black and zirconium nitride impart light-blocking properties to the photocurable resin composition of the present invention by sufficiently blocking light with wavelengths in the visible light region, while allowing sufficient transmission of light with wavelengths in the ultraviolet region or vicinity. Therefore, by using the titanium black or zirconium nitride as the colorant and a photopolymerization initiator that has excellent reactivity to light with wavelengths at which the titanium black or zirconium nitride has a high light transmittance, the photocurable resin composition of the present invention can have excellent light-blocking properties and photocuring properties.

[0049] When a particulate pigment is used as the colorant, the preferred lower limit of the average primary particle diameter of the pigment is 1 nm, and the preferred upper limit is 700 nm. When the average primary particle diameter of the pigment is 1 nm or more, it becomes easier to adjust the optical density of the resulting photocurable resin composition to the range described below. When the average primary particle diameter of the pigment is 700 nm or less, the resulting photocurable resin composition becomes easier to handle. The more preferred lower limit of the average primary particle diameter of the pigment is 5 nm, and the more preferred upper limit is 500 nm, and the even more preferred lower limit is 10 nm, and the even more preferred upper limit is 100 nm. The average primary particle size can be obtained by measuring the particle sizes of 50 or more particles using a scanning electron microscope and calculating the average value.

[0050] The preferred lower limit of the content of the colorant in the photocurable resin composition of the present invention is 0.1% by mass, and the preferred upper limit is 7% by mass. By ensuring that the content of the colorant falls within this range, it becomes easy to adjust the optical density of the resulting photocurable resin composition to the range described below. The more preferred lower limit of the content of the colorant is 0.3% by mass, and the more preferred upper limit is 5% by mass.

[0051] The photocurable resin composition of the present invention preferably further contains a tackifier. Examples of the tackifier include rosin-based resins and terpene-based resins.

[0052] Examples of the rosin-based resin include rosin diol. The rosin diol is not particularly limited as long as it is a rosin-modified diol having two rosin skeletons and two hydroxyl groups in the molecule. Diols having a rosin component in the molecule are called rosin polyols, and these include polyether types such as polypropylene glycol (PPG) in which the skeleton excluding the rosin component is polyether, and polyester types such as condensation polyester polyols, lactone polyester polyols, and polycarbonate diols. Examples of the rosin diol include rosin esters obtained by reacting rosin with polyhydric alcohols, epoxy-modified rosin esters obtained by reacting rosin with epoxy compounds, and modified rosins having hydroxyl groups, such as polyethers having a rosin skeleton, etc. These can be produced by conventionally known methods.

[0053] Examples of the rosin component include abietic acid, abietic acid derivatives such as dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, diabietic acid, and neoabietic acid, pimaric acid-type resin acids such as levopimaric acid, hydrogenated rosins obtained by hydrogenating these, and disproportionated rosins obtained by disproportionating these.

[0054] Commercially available examples of the above rosin-based resins include Pine Crystal KE-100, Pine Crystal KE-311, Pine Crystal KE-359, Pine Crystal KE-604, Pine Crystal KE-615-3, Pine Crystal KR-614, Pine Crystal D-6011, and Pine Crystal D-6250 (all manufactured by Arakawa Chemical Industries, Ltd.).

[0055] Examples of the terpene resin include terpene phenol resin. The terpene phenolic resin is a copolymer of phenol and a terpene resin, which is an essential oil component obtained from natural products such as pine resin and orange peel, and includes fully hydrogenated terpene phenolic resins and partially hydrogenated terpene phenolic resins. Here, the fully hydrogenated terpene phenolic resin is a terpene resin obtained by substantially completely hydrogenating the terpene phenolic resin, and the partially hydrogenated terpene phenolic resin is a terpene resin obtained by partially hydrogenating the terpene phenolic resin. The terpene phenolic resin has a terpene-derived double bond and an aromatic ring double bond derived from a phenol. Therefore, the fully hydrogenated terpene phenolic resin means a resin in which both the terpene moiety and the phenol moiety are completely or almost completely hydrogenated, and the partially hydrogenated terpene phenolic resin means a resin in which the degree of hydrogenation of these moieties is partial rather than complete. The hydrogenation method and reaction format are not particularly limited. Among the above terpene phenol-based resins, commercially available ones include, for example, YS Polystar NH (fully hydrogenated terpene phenol-based resin) manufactured by Yasuhara Chemical Co., Ltd.

[0056] The preferred lower limit of the tackifier content in the photocurable resin composition of the present invention is 5% by mass, and the preferred upper limit is 50% by mass. By ensuring that the tackifier content is within this range, the resulting photocurable resin composition will have superior adhesion to various substrates. The more preferred lower limit of the tackifier content is 10% by mass, and the more preferred upper limit is 40% by mass.

[0057] The photocurable resin composition of the present invention may contain fillers other than those used as the colorants, from the viewpoint of improving printability by adjusting the viscosity. As the filler, an inorganic filler or an organic filler can be used. Examples of the inorganic filler include silica, talc, glass beads, asbestos, gypsum, diatomaceous earth, smectite, bentonite, montmorillonite, sericite, activated clay, alumina, zinc oxide, magnesium oxide, tin oxide, calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, aluminum nitride, silicon nitride, barium sulfate, and calcium silicate. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and (meth)acrylic polymer fine particles. Among these, inorganic fillers are preferred, silica is more preferred, and fumed silica is even more preferred.

[0058] The preferred lower limit of the filler content in the photocurable resin composition of the present invention is 0.3% by mass, and the preferred upper limit is 15% by mass. By having the filler content within this range, the resulting photocurable resin composition can easily adjust its viscosity while maintaining excellent adhesiveness. The more preferred lower limit of the filler content is 0.5% by mass, and the more preferred upper limit is 10% by mass.

[0059] The photocurable resin composition of the present invention may contain an antifoaming agent from the viewpoint of improving printability and the like. Examples of the antifoaming agent include silicone-based antifoaming agents, acrylic polymer-based antifoaming agents, vinyl ether polymer-based antifoaming agents, and olefin polymer-based antifoaming agents.

[0060] The preferred lower limit of the content of the defoaming agent in the photocurable resin composition of the present invention is 0.3% by mass, and the preferred upper limit is 5% by mass. By having the content of the defoaming agent in this range, the resulting photocurable resin composition has better printability. The more preferred lower limit of the content of the defoaming agent is 0.5% by mass, and the more preferred upper limit is 3% by mass.

[0061] The photocurable resin composition of the present invention may further contain various known additives such as a plasticizer, a silane coupling agent, a sensitizer, a heat curing agent, a curing retarder, an antioxidant, a storage stabilizer, and a dispersant, as long as the object of the present invention is not impaired. Furthermore, from the viewpoint of preventing a decrease in photocurability, it is preferable that the photocurable resin composition of the present invention is substantially free of organic solvents. Specifically, it is preferable that the content of organic solvents in the photocurable resin composition is 1.5 mass% or less.

[0062] The photocurable resin composition of the present invention can be prepared, for example, by using a mixer to mix the monofunctional (meth)acrylic monomer, the polyfunctional (meth)acrylic monomer, the photopolymerization initiator, the thermoplastic resin, the colorant, and additives added as needed. Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mill.

[0063] The photocurable resin composition of the present invention is suitable for printing. Forming a pressure-sensitive adhesive layer by printing onto an adherend (substrate) in a desired pattern has the advantage of eliminating the cutting step, compared to when a sheet-shaped pressure-sensitive adhesive is cut immediately before lamination to obtain a pressure-sensitive adhesive of the desired shape. As a result, waste generation can be suppressed, and the environmental load can be reduced.

[0064] The photocurable resin composition of the present invention has a viscosity of 0.1 Pa s at a lower limit and 100 Pa s at an upper limit, as measured at 25°C and 10 rpm using an E-type viscometer. Having the viscosity within this range makes the photocurable resin composition suitable for printing. The preferred lower limit of the viscosity is 0.3 Pa s, the preferred upper limit is 70 Pa s, the more preferred lower limit is 0.5 Pa s, and the more preferred upper limit is 50 Pa s. As the E-type viscometer, for example, VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) can be used.

[0065] The photocurable resin composition of the present invention is prepared by coating the photocurable resin composition on a substrate to a thickness of 50 μm, and then, without sealing the coated surface, applying a photocurable resin composition to a substrate at a wavelength of 315 nm or more and 480 nm or less and an illuminance of 500 mW / cm in an atmospheric environment. 2 The light is irradiated at 3000mJ / cm 2 The lower limit of the reaction rate of the cured product obtained by irradiating the light so as to satisfy the above condition is 90%. As the substrate, a PET film with a release-treated surface (release PET film) is preferably used. The conditions for producing the cured product are that the photocurable resin composition is applied to the substrate, and then the coated surface is irradiated with light in the presence of oxygen without covering it with a separator or the like, so the reaction rate of the cured product reflects the photocurability in the presence of oxygen. When the reaction rate of the cured product is 90% or more, the photocurability in the presence of oxygen is sufficiently high, making it possible to apply a method in which the photocurable resin composition is printed into a desired shape and then bonded to an adherend. The lower limit of the reaction rate of the cured product is preferably 92%, and more preferably 94%. Furthermore, the higher the reactivity of the cured product, the better, but the practical upper limit is 99%. The term "wavelength of 315 nm or more and 480 nm or less" does not mean that the above-mentioned reaction rate of the cured product is satisfied over the entire wavelength range, but means that there is a wavelength within the wavelength range that satisfies the above-mentioned reaction rate of the cured product. The same applies to the gel fraction of the cured product, which will be described later.

[0066] Specifically, the reaction rate of the cured product can be measured, for example, according to the following procedure. That is, first, the photocurable resin composition is coated onto a release PET film substrate to a thickness of 50 μm, and then, without sealing the coated surface, it is irradiated with light at a wavelength of 315 nm to 480 nm and an illuminance of 500 mW / cm using a light irradiation device in an atmospheric environment. 2 The light is irradiated at 3000mJ / cm 2 By irradiating the photocurable resin composition so as to achieve the above-mentioned condition, the photocurable resin composition is cured to obtain a cured product. Approximately 0.3 g of the resulting cured product was placed on an aluminum pan, and a mixed solvent containing THF:acetone:ethanol in an 8:1:1 mass ratio was gently added to prevent the cured sample from scattering. The sample was allowed to swell for approximately 2 hours. The sample was then dried at 110°C for 30 minutes, 170°C for 1 hour, and 190°C for 30 minutes. The mass of the dried aluminum pan and the dried sample were then weighed, and the reaction rate of the cured product was calculated using the following formula: Reaction rate of cured product (%) = (total mass of aluminum pan and sample after drying - mass of aluminum pan before drying) / (mass of sample before swelling) × 100

[0067] The photocurable resin composition of the present invention has a gel fraction of 10% by mass or less and 80% by mass or less, obtained in the same manner as the cured product according to the above-mentioned cured product reactivity. When the gel fraction of the cured product is within the above range, the photocurable resin composition of the present invention exhibits excellent adhesion and creep resistance. The gel fraction of the cured product is preferably 25% by mass or less and 60% by mass or less, more preferably 30% by mass or less and 50% by mass or less.

[0068] Specifically, the gel fraction of the cured product can be measured, for example, according to the following procedure. That is, first, 0.15 g of the cured product obtained in the same manner as in measuring the reactivity of the cured product above was weighed into a glass bottle, and then immersed in 30 g of tetrahydrofuran and immersed with shaking at 23°C for 36 hours. Next, the cured product was removed through a 200-mesh filter and dried by heating at 110°C for 1 hour. The mass of the cured product was then measured, and the gel fraction could be calculated using the following formula. Gel fraction of cured product (mass%) = (W2 / W1) × 100 W1: Mass of the cured product before immersion in tetrahydrofuran at 23°C W2: Mass of the cured product after immersion in tetrahydrofuran at 23°C, removal, and drying

[0069] The photocurable resin composition of the present invention has a cured product with a glass transition temperature of preferably -10°C at its lower limit and 25°C at its upper limit. When the glass transition temperature of the cured product is within this range, the resulting photocurable resin composition exhibits superior adhesion to various substrates. The cured product's glass transition temperature is more preferably -5°C at its lower limit and 15°C at its upper limit. The glass transition temperature of the cured product can be measured by the following method. That is, the glass transition temperature can be determined as the tan δ peak temperature when dynamic viscoelasticity measurement is performed on the cured product of the photocurable resin composition using a dynamic viscoelasticity measuring device under the following conditions. The dynamic viscoelasticity measuring device may be, for example, a DVA-200 (manufactured by IT Measurement & Control Co., Ltd.). The cured product for which the glass transition temperature is measured may be, for example, a 1.0 mm thick laminate of cured products obtained in the same manner as in the measurement of the cured product reactivity. <Condition> Shear Method Measurement temperature: -70℃~200℃ Heating rate: 1°C / min Distortion: 0.1% Frequency: 1Hz

[0070] The photocurable resin composition of the present invention has an optical density (hereinafter also referred to as "OD value") of 2.0 or more when cured at a thickness of 1.0 mm. Since the OD value of the cured product is 2.0 or more, the photocurable resin composition of the present invention can be suitably used in applications requiring light-blocking properties. The OD value of the cured product is preferably 3.0 or more, and more preferably 4.0 or more. The higher the OD value of the cured product, the better. However, if too much colorant is added in order to increase the OD value of the cured product, the viscosity increases, resulting in reduced workability, and so on. Therefore, the practical upper limit of the OD value of the cured product is 10.0. The OD value of the cured product can be measured using an optical densitometer. The OD value of the cured product can be measured, for example, by laminating cured products obtained in the same manner as in the measurement of the reaction rate of the cured product to a thickness of 1.0 mm.

[0071] The photocurable resin composition of the present invention can be cured by irradiating it with light to form a pressure-sensitive adhesive layer. Its use may involve forming a pressure-sensitive adhesive layer on a substrate (separator) to produce a pressure-sensitive adhesive sheet that can be transferred to an adherend, or it may involve forming a pressure-sensitive adhesive layer directly on an adherend. The method of forming a pressure-sensitive adhesive layer directly on an adherend minimizes the number of laminations and prevents air bubbles from being introduced at the interface during lamination. On the other hand, the method of forming a pressure-sensitive adhesive layer on a substrate (separator) has the advantage of fewer application constraints, since the pressure-sensitive adhesive layer is placed on the adherend by transfer.

[0072] The present invention also includes a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a cured product of the photocurable resin composition of the present invention. The pressure-sensitive adhesive sheet of the present invention may be a non-support type pressure-sensitive adhesive sheet that does not have a substrate, or may be a supported type pressure-sensitive adhesive sheet, i.e., a pressure-sensitive adhesive sheet that has a substrate and a pressure-sensitive adhesive layer containing a cured product of the photocurable resin composition of the present invention on at least one surface of the substrate.

[0073] When the pressure-sensitive adhesive sheet of the present invention has a substrate, it may be a single-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer on one side of the substrate, or a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layers on both sides of the substrate.

[0074] Examples of the substrate include sheets made of resins such as acrylic resin, olefin resin, polycarbonate, polyvinyl chloride, ABS resin, polyethylene terephthalate (PET), nylon, polyurethane, and polyimide. The shape of the substrate is not particularly limited, and it may have a mesh structure or may have holes.

[0075] The present invention also includes a method for producing a laminate, which includes the steps of printing the photocurable resin composition of the present invention and attaching an adherend to the printed photocurable resin composition.

[0076] In the method for producing a laminate of the present invention, examples of a method for printing the photocurable resin composition of the present invention include screen printing, inkjet printing, flexographic printing, gravure printing, slot die coating, knife coating, spray coating, spin coating, stencil printing, dispensing, jet dispensing, reverse offset printing, etc. Among these, screen printing, inkjet printing, or flexographic printing is preferred, and screen printing is more preferred.

[0077] Examples of the material of the adherend include metals such as stainless steel and aluminum, and resins. [Effects of the Invention]

[0078] According to the present invention, it is possible to provide a photocurable resin composition that is excellent in printability, photocurability in the presence of oxygen, adhesiveness, creep resistance, and light-shielding property. Furthermore, according to the present invention, it is possible to provide a pressure-sensitive adhesive sheet using the photocurable resin composition, and a method for producing a laminate using the photocurable resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0079] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0080] (Examples 1 to 17, Comparative Examples 1 to 6) According to the compounding ratios shown in Tables 1 to 3, the materials were mixed in a planetary mixer (Thinky Corporation, "Awatori Rentaro") to obtain photocurable resin compositions of the examples and comparative examples. Details of the materials indicated by abbreviations in the table are as follows: (Monofunctional (meth)acrylic monomer) CBA: Ethyl carbitol acrylate (Osaka Organic Chemical Industry Co., Ltd., "Viscoat #190") MEDOL-10: (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (Osaka Organic Chemical Industry Co., Ltd.) M-140: N-acryloyloxyethylhexahydrophthalimide (manufactured by Toagosei Co., Ltd., a nitrogen-containing ring compound) (Polyfunctional (meth)acrylic monomer) UA-160TM: Polyether-based multifunctional urethane acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) (Nitrogen-containing ring compound) CHMI: N-cyclohexylmaleimide (Nippon Shokubai Co., Ltd.) (Photopolymerization initiator) Omnipol TP: Ethyl (2,4,6-trimethylbenzoyl)-phenylphosphonate polymer (manufactured by IGM Resins, a Norrish type I photopolymerization initiator with a weight-average molecular weight of 1200) Omnipol 910: Polyethylene glycol di(β-4(4-(2-dimethylamino-2-benzyl)butanoylphenyl)piperazine)propionate (manufactured by IGM Resins, a Norrish type I photopolymerization initiator with a weight-average molecular weight of 1100) Omnirad 369: 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (manufactured by IGM Resins, a Norrish type I photoinitiator with a molecular weight of 366.5) (thermoplastic resin) Polymer A: Acrylic random copolymer (manufactured by Saiden Chemical Co., Ltd., weight average molecular weight 460,000, monomer composition (butyl acrylate and 2-ethylhexyl acrylate)) LA2330: Acrylic triblock copolymer (Kuraray Co., Ltd., weight average molecular weight 120,000) Polymer B: Acrylic / styrene triblock copolymer (styrene / butyl acrylate / styrene triblock copolymer, styrene-derived structure content: 20% by mass, weight-average molecular weight: 300,000, triblock ratio: 90%) Polymer C: Acrylic graft copolymer obtained in the "(Synthesis of Polymer C)" section below (coloring agent) Titanium black (Mitsubishi Materials Corporation, "13M-C") Zirconium nitride (Mitsubishi Materials Electronic Chemicals Co., Ltd., "UB-2") Carbon black (Mitsubishi Chemical Corporation, "MA100") (tackifier) KE-359: Rosin ester (manufactured by Arakawa Chemical Industries, Ltd.) D-6011: Rosindiol (Arakawa Chemical Industries, Ltd.) (filler) R805: Fumed silica (manufactured by Nippon Aerosil Co., Ltd.) (Antifoaming agent) KS-66: Silicone antifoaming agent (Shin-Etsu Chemical Co., Ltd.)

[0081] (Synthesis of Polymer C) A reactor equipped with a thermometer, stirrer, and cooling tube was prepared. 73.8 parts by mass of butyl acrylate, 0.2 parts by mass of acrylic acid, 20 parts by mass of ethylene-butylene macromonomer, 0.014 parts by mass of lauryl mercaptan, and 80 parts by mass of ethyl acetate were added to the reactor, and the reactor was heated to initiate reflux. Subsequently, 0.01 parts by mass of 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane was added as a polymerization initiator to initiate polymerization under reflux. Next, 0.01 parts by mass of 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane were added one hour and two hours after the start of polymerization. Furthermore, 0.05 parts by mass of t-hexylperoxypivalate was added four hours after the start of polymerization to continue the polymerization reaction. Eight hours after the start of polymerization, an ethyl acetate solution of polymer C with a solids content of 60% by mass and a weight-average molecular weight of 480,000 was obtained. The weight average molecular weight of the obtained polymer C was measured using gel permeation chromatography (Waters, "2690 Separations Module" or the like) under the following conditions. <Condition> Solvent: tetrahydrofuran Sample flow rate: 1 mL / min Detector: Differential refractive index RI Column: GPC KF-806L (Showa Denko) Column temperature (measurement temperature): 40°C Injection volume: 20μL

[0082] (viscosity) 0.4 mL of the obtained photocurable resin composition was sampled, and the viscosity was measured using a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer with a CP1 cone plate at 25°C and 10 rpm. The results are shown in Tables 1 to 3.

[0083] (Reaction rate of cured product) The obtained photocurable resin composition was applied to a release PET film (Nippa Corporation, "1-E", thickness 50 μm) using an applicator to a thickness of 50 μm. Next, in an atmospheric environment without sealing the coated surface, a UV-LED irradiation device (CS Corporation, "UVS01-01") was used to irradiate the film with a wavelength of 365 nm and an illuminance of 500 mW / cm. 2 The light is irradiated at 3000mJ / cm 2 Thereafter, the air side of the cured product was sealed with a release PET film (manufactured by Nippa Corporation, "1-C", thickness 38 μm), to obtain a laminate. Both release films were peeled from the resulting laminate, and approximately 0.3 g of the cured photocurable resin composition was placed on an aluminum pan with a diameter of 10 cm and a height of 1 cm. A mixed solvent containing THF:acetone:ethanol in an 8:1:1 mass ratio was gently added to prevent the cured sample from scattering, and the sample was allowed to swell for approximately 2 hours. The sample was then dried at 110°C for 30 minutes, 170°C for 1 hour, and 190°C for 30 minutes. The masses of the aluminum pan and the dried sample after drying were weighed, and the reaction rate of the cured product was calculated using the following formula. The results are shown in Tables 1 to 3. Reaction rate of cured product (%) = (total mass of aluminum pan and sample after drying - mass of aluminum pan before drying) / (mass of sample before swelling) × 100

[0084] (Gel fraction of cured product) Both release films were peeled off from the laminate obtained in the same manner as in "(Reaction rate of the cured product)" above, and 0.15 g of the cured product of the photocurable resin composition was weighed into a glass bottle, which was then immersed in 30 g of tetrahydrofuran and immersed with shaking at 23°C for 36 hours. The cured product was then removed through a 200-mesh filter and dried by heating at 110°C for 1 hour. The mass of the cured product was then measured, and the gel fraction was calculated using the following formula. The results are shown in Tables 1 to 3. Gel fraction of cured product (mass%) = (W2 / W1) × 100 W1: Mass of the cured product before immersion in tetrahydrofuran at 23°C W2: Mass of the cured product after immersion in tetrahydrofuran at 23°C, removal, and drying

[0085] (glass transition temperature of cured product) Both release films were peeled off from the laminate obtained in the same manner as in "(Reaction rate of the cured product)" above, and the cured product of the photocurable resin composition was laminated to a thickness of 1.0 mm. This was then attached to a jig and subjected to dynamic viscoelasticity measurement under the following conditions using a dynamic viscoelasticity measuring device (IT Measurement and Control Co., Ltd., "DVA-200") to obtain a viscoelasticity chart. The tan δ peak temperature in the obtained viscoelasticity chart was determined as the glass transition temperature. The results are shown in Tables 1 to 3. <Condition> Shear Method Measurement temperature: -70~200℃ Heating rate: 1°C / min Distortion: 0.1% Frequency: 1Hz

[0086] (OD value of cured product) Both release films were peeled off from the laminate obtained in the same manner as in "(Reaction rate of the cured product)" above, and the cured product of the photocurable resin composition was laminated to a thickness of 1.0 mm, and the OD value was measured using an optical densitometer (manufactured by X-rite, "Spectrometer"). The results are shown in Tables 1 to 3.

[0087] <Evaluation> The photocurable resin composition obtained was evaluated as follows, and the results are shown in Tables 1 to 3.

[0088] (Printability) (1) Coating method (1-1) Flexographic printing The obtained photocurable resin composition was coated onto a release PET film (Nippa Corporation, "1-E", thickness 50 μm) using a flexographic printing device (MT Tech Corporation, "Small Flexographic Printing Tester FC11") to a thickness of approximately 10 μm. Next, using a UV-LED irradiation device (CS Corporation, "UVS01-01"), the coating was irradiated with light at a wavelength of 365 nm and an illuminance of 500 mW / cm. 2 The light is irradiated at 3000mJ / cm 2 A cured product was obtained by irradiating the film so as to obtain a cured product. (1-2) Screen printing The photocurable resin composition thus obtained was applied to the inner treated surface of an easily adhesive polyester film (Cosmoshine A4100, manufactured by Toyobo Co., Ltd.) using a screen printer (Micro-Tec Co., Ltd., "LABTOP 38") to form a pattern on the film, which was then screen-printed to a thickness of approximately 50 μm. A patterned 80-mesh screen printing plate was used. Next, a UV-LED irradiation device (CS Inc., "UVS01-01") was used to apply the photocurable resin composition to the inner treated surface of the film, which was then patterned to a thickness of approximately 50 μm. 2 The light is irradiated at 3000mJ / cm 2 A cured product was obtained by irradiating the film so as to obtain a cured product. (1-3) Inkjet printing The obtained photocurable resin composition was applied to a release PET film (Nippa's "1-E", thickness 50 μm) using an inkjet device (Fujifilm's "Material Printer DMP-2831") to a thickness of approximately 2 μm. Next, using a UV-LED irradiation device (CS Inc.'s "UVS01-01"), the coating was applied to a release PET film (Nippa's "1-E", thickness 50 μm) to a thickness of approximately 2 μm. 2 The light is irradiated at 3000mJ / cm 2 A cured product was obtained by irradiating the film so as to obtain a cured product.

[0089] (2) Evaluation of printability The resulting cured product was visually inspected and the printability was evaluated according to the following criteria. ○: When a cured product with uniform thickness and surface smoothness was obtained ×: Uneven thickness, surface irregularities or repelling

[0090] (Adhesion (180° peel adhesive strength)) The photocurable resin composition obtained was applied to the inner treated surface of an adhesive polyester film (Cosmoshine A4100, manufactured by Toyobo Co., Ltd.) using an applicator to a thickness of approximately 50 μm. The coated surface was then exposed to UV-LED irradiation at a wavelength of 365 nm and an illuminance of 500 mW / cm using a UV-LED irradiation device (UVS01-01, manufactured by CCS Inc.) in an atmospheric environment without sealing the coated surface. 2 The light is irradiated at 3000mJ / cm 2 A cured product was obtained by irradiating the sample so that the temperature reached 100°C. The surface was then sealed with a release PET film (Nippa Corporation, "1-C," 38 μm thick) and cut to a width of 25 mm and a length of 200 mm (adhesion surface 25 mm x 125 mm) to produce a laminated film. The release PET film was then peeled off from the laminated film, and the exposed surface was attached to a SUS substrate. A test specimen was obtained by pressing the exposed surface back and forth with a 2 kg roller. The resulting test specimen was stored at 25°C for 24 hours, and the 180° peel adhesive strength was measured by performing a 180° peel at a speed of 300 mm / min using a universal testing machine (A&D Corporation, "Tensilon RTI-1310").

[0091] (Creep resistance) The laminate obtained in the same manner as in "(Cured Product Reaction Rate)" above was cut into a 25mm x 25mm piece. One release PET film (1-C) was peeled off, and the cured product was bonded to a mirror-polished SUS substrate 25mm wide, 100mm long, and 2mm thick with a 5mm hole at the long edge. Next, the other release PET film (1-E) was peeled off, and the exposed cured product was bonded to the mirror-polished surface of a similar SUS substrate. The specimen was then pressed at 215N using a universal testing machine (A&D Co., Ltd., "Tensilon RTI-1310") and left to stand at 25°C for 24 hours to obtain a test specimen. The obtained test piece was hung from one of the SUS substrates by an S-shaped hook, and a 1 kg weight was hung from the other SUS substrate. This was left at 25°C, and the time until the weight fell was measured, and the creep resistance was evaluated according to the following criteria. ○: The weight did not fall even after 48 hours △: The time it took for the weight to fall was more than 24 hours but less than 48 hours. ×: The weight took less than 24 hours to fall

[0092] (Light blocking property) The light-blocking properties were evaluated based on the OD values ​​measured in the above "(OD value of the cured product)" according to the following criteria. ○: OD value was 2.0 or more ×: OD value was less than 2.0

[0093] [Table 1]

[0094] [Table 2]

[0095] [Table 3] [Industrial Applicability]

[0096] According to the present invention, it is possible to provide a photocurable resin composition that is excellent in printability, photocurability in the presence of oxygen, adhesiveness, creep resistance, and light-shielding property. Furthermore, according to the present invention, it is possible to provide a pressure-sensitive adhesive sheet using the photocurable resin composition, and a method for producing a laminate using the photocurable resin composition.

Claims

1. a photocurable resin composition containing a monofunctional (meth)acrylic monomer, a polyfunctional (meth)acrylic monomer, a photopolymerization initiator, a thermoplastic resin, and a colorant; the content of the polyfunctional (meth)acrylic monomer is 0.1 parts by mass or more and 30 parts by mass or less based on 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer; the content of the photopolymerization initiator is 0.5 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the total content of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer, the thermoplastic resin has a block structure or a graft structure, the content of the thermoplastic resin in the photocurable resin composition is 5% by mass or more and 60% by mass or less, the viscosity of the photocurable resin composition measured using an E-type viscometer at 25°C and 10 rpm is 0.1 Pa s or more and 100 Pa s or less; The photocurable resin composition was applied to a substrate to a thickness of 50 μm, and the coated surface was not sealed, and the coating was then exposed to light at a wavelength of 315 nm or more and 480 nm or less at an illuminance of 500 mW / cm in an atmospheric environment. ２ The light is irradiated at a dose of 3000 mJ / cm ２ a cured product obtained by irradiating the cured product so as to satisfy the above condition has a reaction rate of 90% or more and a gel fraction of 10% by mass or more and 80% by mass or less, The optical density of a cured product of the photocurable resin composition having a thickness of 1.0 mm is 2.0 or more. A photocurable resin composition comprising:

2. 2. The photocurable resin composition according to claim 1, wherein the colorant is titanium black or zirconium nitride.

3. 3. The photocurable resin composition according to claim 1, wherein the thermoplastic resin comprises a thermoplastic resin having a structure derived from styrene.

4. 4. The photocurable resin composition according to claim 3, wherein the thermoplastic resin having a structure derived from styrene is a (meth)acrylic / styrene copolymer.

5. 4. The photocurable resin composition according to claim 3, wherein the content of the styrene-derived structure in the thermoplastic resin having the styrene-derived structure is 5% by mass or more.

6. 3. The photocurable resin composition according to claim 1, wherein the thermoplastic resin contains a triblock copolymer, and the content of the triblock copolymer in the thermoplastic resin is 50% by mass or more.

7. 3. The photocurable resin composition according to claim 1, wherein the thermoplastic resin has a weight average molecular weight of 100,000 or more and 500,000 or less.

8. 3. The photocurable resin composition according to claim 1, wherein the photopolymerization initiator has a weight average molecular weight of 500 or more.

9. 3. The photocurable resin composition according to claim 1, wherein the photopolymerization initiator has two or more carbonyl groups per molecule that contribute to a Norrish type I cleavage reaction.

10. 3. The photocurable resin composition according to claim 1, further comprising an antifoaming agent.

11. 3. The photocurable resin composition according to claim 1, further comprising an inorganic filler.

12. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising a cured product of the photocurable resin composition according to claim 1 or 2.

13. The pressure-sensitive adhesive sheet according to claim 12, comprising a substrate and a pressure-sensitive adhesive layer containing a cured product of the photocurable resin composition on at least one surface of the substrate.

14. A method for producing a laminate, comprising the steps of printing the photocurable resin composition according to claim 1 or 2, and attaching an adherend to an object using the printed photocurable resin composition.

15. The method for producing a laminate according to claim 14, wherein the method for printing the photocurable resin composition is screen printing, inkjet printing, or flexographic printing.

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