Photocurable pressure-sensitive adhesive composition, laminate, pressure-sensitive adhesive tape, and method for producing pressure-sensitive adhesive tape

Abstract

A purpose of the present invention is to provide a photocurable pressure-sensitive adhesive composition which can lessen burdens on the environment and health and has excellent applicability or printability and excellent adhesiveness and holding properties. Another purpose of the present invention is to provide: a laminate and a pressure-sensitive adhesive tape each obtained using the photocurable pressure-sensitive adhesive composition; and a method for producing the pressure-sensitive adhesive tape using the photocurable pressure-sensitive adhesive composition. This photocurable pressure-sensitive adhesive composition comprises one or more polymerizable monomers, a photopolymerization initiator, and a thermoplastic resin, wherein the polymerizable monomers include at least one monofunctional (meth)acrylate monomer selected from among n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate, the content of the at least one monofunctional (meth)acrylate monomer selected from among n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate being 68 parts by mass or lager per 100 parts by mass of the polymerizable monomers. The photocurable pressure-sensitive adhesive composition contains no solvent or has a solvent content higher than 0 mass% but not higher than 1 mass%.

Description

Photocurable adhesive composition, laminate, adhesive tape, and method for manufacturing adhesive tape

[0001] The present invention relates to a photocurable adhesive composition. The present invention also relates to a laminate and an adhesive tape using the photocurable adhesive composition, and to a method for manufacturing an adhesive tape using the photocurable adhesive composition.

[0002] Adhesives are typically used to bond electronic components inside electronic devices such as smartphones and PCs. A common method of bonding with adhesives is the use of adhesive tapes having an adhesive layer formed using an adhesive (for example, Patent Documents 1 to 3).

[0003] In bonding substrates with adhesive tape, typically, first, an adhesive tape with separators on both sides of the adhesive layer is cut to the desired shape. Then, one separator is peeled off from the cut adhesive tape, and one side of the exposed adhesive layer is bonded to the substrate. Subsequently, the other separator is peeled off, and the other side of the exposed adhesive layer is bonded to another substrate.

[0004] When adhesive tape is used to bond objects together, a portion of the tape is discarded as waste after cutting. Therefore, a method is being considered in which an adhesive composition is printed into the desired shape before being bonded to the object, as an alternative to using adhesive tape. This method can reduce the generation of waste. For example, Patent Documents 4 and 5 describe photocurable adhesive compositions that can be used in such a method.

[0005] Japanese Patent Publication No. 2015-052050, Japanese Patent Publication No. 2015-021067, Japanese Patent Publication No. 2015-120876, Japanese Patent Publication No. 2013-216742, International Publication No. 2016 / 163152

[0006] Adhesive compositions typically contain solvents to improve coating properties. These solvents are removed during processes such as drying when forming the adhesive layer of adhesive tape or after printing on the substrate. However, completely removing solvents is difficult, and there are concerns about the environmental and health effects of residual solvents. For this reason, solvent-free photocurable adhesive compositions using low-viscosity materials have been developed. However, conventional photocurable adhesive compositions have problems such as difficulty in sufficiently curing when irradiated with light in an atmospheric environment, i.e., in the presence of oxygen, and insufficient adhesion and retention (creep resistance) after curing. In particular, it has been difficult to obtain excellent retention (creep resistance) at both low and high loads.

[0007] The present invention aims to provide a photocurable adhesive composition that can reduce the burden on the environment and health, and has excellent coating or printability, adhesion, and retention (low and high load). The present invention also aims to provide laminates and adhesive tapes using the photocurable adhesive composition, and a method for manufacturing adhesive tapes using the photocurable adhesive composition.

[0008] Disclosure 1 is a photocurable adhesive composition containing a polymerizable monomer, a photopolymerization initiator, and a thermoplastic resin, wherein the polymerizable monomer comprises at least one monofunctional (meth)acrylic monomer selected from n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate, and the content of at least one monofunctional (meth)acrylic monomer selected from n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate is 68 parts by mass or more per 100 parts by mass of the polymerizable monomer, and the photocurable adhesive composition does not contain a solvent, or the solvent content is greater than 0% by mass and less than or equal to 1% by mass. Disclosure 2 is a photocurable adhesive composition of Disclosure 1 further comprising a tackifier. Disclosure 3 is a photocurable adhesive composition of Disclosure 1 or 2, comprising a thermoplastic resin having a structure derived from at least one monofunctional (meth)acrylic monomer selected from n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate. Disclosure 4 is a photocurable adhesive composition of Disclosure 3, comprising a thermoplastic resin having a structure derived from n-heptyl (meth)acrylate. Disclosure 5 is a photocurable adhesive composition of Disclosure 1, 2, 3, or 4, wherein the thermoplastic resin has a weight-average molecular weight of 100,000 or more and 1,000,000 or less. Disclosure 6 is a photocurable adhesive composition of Disclosure 1, 2, 3, 4, or 5, wherein the polymerizable monomer further contains a nitrogen-containing vinyl compound, and the content of the nitrogen-containing vinyl compound in 100 parts by mass of the polymerizable monomer is 0.5 parts by mass or more and 30 parts by mass or less. Disclosure 7 is a photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, or 6, wherein the photocurable adhesive composition does not contain an aromatic polyisocyanate having a structure derived from toluene diisocyanate. Disclosure 8 is a photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, or 7, further containing an antifoaming agent. Disclosure 9 is a photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, or 8, further containing a leveling agent.Disclosure 10 is a photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, further containing an inorganic filler. Disclosure 11 is a photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the thixotropic index, which is the value obtained by dividing the viscosity measured at 25°C and 1 rpm using an E-type viscometer by the viscosity measured at 25°C and 10 rpm, is 1.05 or more and 5.00 or less. Disclosure 12 is a photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, used for printing. Disclosure 13 is a photocurable adhesive composition of Disclosure 12, used for screen printing, wherein the viscosity measured at 25°C and 10 rpm using an E-type viscometer is 1 Pa·s or more and 400 Pa·s or less. Disclosure 14 is a photocurable adhesive composition of Disclosure 12, used in inkjet printing, having a viscosity of 0.001 Pa·s or more and 10 Pa·s or less, as measured using an E-type viscometer at 25°C and 10 rpm. Disclosure 15 is a laminate having a cured product of the photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, and a release film on at least one side of the cured product. Disclosure 16 is an adhesive tape having an adhesive layer containing a cured product of the photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14. Disclosure 17 is a method for manufacturing an adhesive tape, comprising the steps of coating a photocurable adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 onto a film, and irradiating the coated photocurable adhesive composition with light to form an adhesive layer. The present invention will be described in detail below.

[0009] The inventors investigated a photocurable adhesive composition containing a polymerizable monomer, a photopolymerization initiator, and a thermoplastic resin, and containing little to no solvent, and further investigating the inclusion of a specific monofunctional (meth)acrylic monomer as the polymerizable monomer in a specific proportion. As a result, they found that it is possible to obtain a photocurable adhesive composition that reduces the burden on the environment and health, and has excellent coating or printability, adhesion, and retention properties, thus completing the present invention.

[0010] The photocurable adhesive composition of the present invention contains a polymerizable monomer. The polymerizable monomer includes at least one monofunctional (meth)acrylic monomer selected from n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate (hereinafter also referred to as "the monofunctional (meth)acrylic monomer of the present invention"). By using the monofunctional (meth)acrylic monomer of the present invention in the content described below, the photocurable adhesive composition of the present invention contains no solvent or very little solvent, yet exhibits excellent coating properties and adhesive properties. In this specification, "(meth)acrylate" means acrylate or methacrylate, "(meth)acrylic" means acrylic or methacrylic, and "monofunctional (meth)acrylic monomer" means a monomer having one (meth)acryloyl group in one molecule. In this specification, "(meth)acryloyl" means acryloyl or methacryloyl.

[0011] The polymerizable monomer described above may contain only the monofunctional (meth)acrylic monomer according to the present invention as a monofunctional (meth)acrylic monomer. However, from the viewpoint of achieving superior retention (creep resistance), it is preferable to include other monofunctional (meth)acrylic monomers other than the monofunctional (meth)acrylic monomer according to the present invention.

[0012] Examples of the other monofunctional (meth)acrylic monomers mentioned above include monofunctional (meth)acrylic acid ester compounds other than the monofunctional (meth)acrylic monomers of the present invention, monofunctional (meth)acrylamide compounds, monofunctional (meth)acrylimide compounds, and the like.

[0013] Examples of monofunctional (meth)acrylic acid ester compounds other than monofunctional (meth)acrylic monomers according to the present invention 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, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isomiristyl (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. Rate, 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 succinic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 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, (3-ethyl Examples include oxetane-3-yl)propyl (meth)acrylate, (3-ethyloxetane-3-yl)butyl (meth)acrylate, (3-ethyloxetane-3-yl)pentyl (meth)acrylate, (3-ethyloxetane-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.

[0014] Examples of the above monofunctional (meth)acrylamide compounds 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.

[0015] Examples of the above-mentioned monofunctional (meth)acrylimide compounds include N-(meth)acryloyloxyethylhexahydrophthalimide.

[0016] The lower limit of the content of the monofunctional (meth)acrylic monomer according to the present invention in 100 parts by mass of the polymerizable monomer is 68 parts by mass. A content of 68 parts by mass or more of the monofunctional (meth)acrylic monomer according to the present invention results in the photocurable adhesive composition of the present invention exhibiting excellent adhesion to various substrates. A preferred lower limit for the content of the monofunctional (meth)acrylic monomer according to the present invention is 70 parts by mass, and a more preferred lower limit is 80 parts by mass. Furthermore, from the viewpoint of achieving superior retention (creep resistance), a preferred upper limit for the content of the monofunctional (meth)acrylic monomer according to the present invention is 98 parts by mass, and a more preferred upper limit is 96 parts by mass.

[0017] The polymerizable monomer preferably contains a polyfunctional (meth)acrylic monomer. The polyfunctional (meth)acrylic monomer acts as a crosslinking component. In this specification, "polyfunctional (meth)acrylic monomer" means a monomer having two or more (meth)acryloyl groups in one molecule.

[0018] Examples of the polyfunctional (meth)acrylic monomers mentioned above include polyfunctional urethane (meth)acrylates, polyfunctional (meth)acrylic acid ester compounds, and polyfunctional epoxy (meth)acrylates. In this specification, "epoxy (meth)acrylate" refers to a compound obtained by reacting all epoxy groups in an epoxy compound with (meth)acrylic acid.

[0019] The above-mentioned 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-based compound.

[0020] Examples of isocyanate compounds that serve as raw materials for the above-mentioned polyfunctional urethane (meth)acrylates 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, tollidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanatephenyl)thiophosphate, tetramethylxylylene diisocyanate, and 1,6,11-undecane triisocyanate.

[0021] Furthermore, as the isocyanate compound used as a raw material for the above-mentioned polyfunctional urethane (meth)acrylate, a chain-extended isocyanate compound obtained by the reaction of a polyol with an excess isocyanate compound can also be used. Examples of the above-mentioned polyols include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

[0022] Examples of (meth)acrylic acid derivatives having a hydroxyl group include hydroxyalkyl mono(meth)acrylate, mono(meth)acrylate of a dihydric alcohol, mono(meth)acrylate or di(meth)acrylate of a trihydric alcohol. Examples of hydroxyalkyl mono(meth)acrylate include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate. Examples of dihydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of trihydric alcohols include trimethylolethane, trimethylolpropane, and glycerin.

[0023] Examples of the above polyfunctional (meth)acrylic acid ester compounds 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, and 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 dicyclopentadienyl Di(meth)acrylate, ethylene oxide-modified isocyanurate 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, trimeth Rollpropane 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 isocyanurate tri(meth)acrylate, glycerin tri(meth)acrylate, propylene oxide-added glycerin tri(meth)acrylate Examples include pentaerythritol tri(meth)acrylate, tris(meth)acryloyloxyethyl phosphate, ditrimethylolpropanetetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and the like.

[0024] Examples of the polyfunctional epoxy (meth)acrylates mentioned above include bisphenol A type epoxy (meth)acrylate, bisphenol F type epoxy (meth)acrylate, bisphenol E type epoxy (meth)acrylate, and caprolactone-modified versions thereof.

[0025] The preferred lower limit for the content of the polyfunctional (meth)acrylic monomer in 100 parts by mass of the polymerizable monomer is 2 parts by mass, and the preferred upper limit is 15 parts by mass. Having the polyfunctional (meth)acrylic monomer content within this range results in a photocurable adhesive composition with superior adhesion and retention (creep resistance) to various substrates. A more preferred lower limit for the polyfunctional (meth)acrylic monomer content is 3 parts by mass, and a more preferred upper limit is 10 parts by mass.

[0026] Preferably, the polymerizable monomer further contains a nitrogen-containing vinyl compound. The inclusion of the nitrogen-containing vinyl compound results in a photocurable adhesive composition with superior photocurability in the presence of oxygen.

[0027] The nitrogen-containing vinyl compound preferably contains at least one selected from the group consisting of a monofunctional radical polymerizable monomer having a lactam structure and a maleimide derivative, and more preferably contains a maleimide derivative. The reaction system of the monofunctional radical polymerizable monomer having a lactam structure and the maleimide derivative basically proceeds by a hydrogen abstraction reaction. Photoradical polymerization by hydrogen abstraction is less susceptible to oxygen inhibition, so surface curability can be increased. In addition, photoradical polymerization by hydrogen abstraction yields branched polymers and increases cohesive force. Therefore, by including the monofunctional radical polymerizable monomer having a lactam structure and the maleimide derivative, the resulting photocurable adhesive composition can produce a cured product that is less prone to bleeding due to a decrease in surface curability and less prone to cohesive failure due to a decrease in surface curability and cohesive force. In this specification, "maleimide derivative" means a compound having a maleimide group.

[0028] Among the maleimide derivatives mentioned above, monofunctional maleimides include, for example, 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, N-ethylmaleimide, N-isopropylmaleimide, N- Examples include 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, maleimide derivatives that do not have a structure in which hydrogen is bonded to a heteroatom are preferred from the viewpoint of improving the reaction rate. Furthermore, from the viewpoint of improving adhesive strength, maleimide derivatives having a structure in which hydrogen is bonded to a heteroatom may be used. Specifically, as the above monofunctional maleimide, at least one selected from the group consisting of N-cyclohexylmaleimide, 4-hydroxyphenylmaleimide, and N-(4-carboxycyclohexylmethyl)maleimide is preferred, and N-cyclohexylmaleimide is more preferred.Furthermore, among the above maleimide derivatives, polyfunctional maleimides include, for example, N,N'-methylenebismaleimide, N,N'-trimethylenebismaleimide, N,N'-dodecamethylenebismaleimide, N,N'-(4,4'-diphenylmethane)bismaleimide, 1,4-dimaleimidecyclohexane, isophoronebisurethanebis(N-ethylmaleimide), N,N'-P-phenylenebismaleimide, N,N'-m-phenylenebismaleimide, N,N'-m-toluylenebismaleimide, and N,N'-4,4'-biphenyl Examples include lenbismaleimide, 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'-diphenylpropanebismaleimide, N,N'-4,4'-diphenyletherbismaleimide, N,N'-3,3'-diphenylsulfonebismaleimide, and N,N'-4,4'-diphenylsulfonebismaleimide. From the viewpoint of improving the reaction rate, the above monofunctional maleimides and these polyfunctional maleimides may be used in combination as maleimide derivatives, but it is not preferable to use a large amount of polyfunctional maleimide in combination because the gel fraction becomes too high.

[0029] The monofunctional radical polymerizable monomer having the above lactam structure is preferably a compound represented by the following formula (1).

[0030]

[0031] In equation (1), n ​​represents an integer between 2 and 6.

[0032] Examples of compounds represented by the above formula (1) include N-vinyl-2-pyrrolidone and N-vinyl-ε-caprolactam. Among these, N-vinyl-ε-caprolactam is preferred.

[0033] The preferable lower limit of the content of the nitrogen-containing vinyl compound in 100 parts by mass of the above-mentioned polymerizable monomer is 0.5 parts by mass, and the preferable upper limit is 30 parts by mass. When the content of the nitrogen-containing vinyl compound is within this range, the obtained cured product becomes excellent in surface curability and adhesiveness to various base materials. A more preferable upper limit of the content of the nitrogen-containing vinyl compound is 20 parts by mass, and a further preferable upper limit is 5.0 parts by mass.

[0034] The preferable lower limit of the content ratio of the above-mentioned polymerizable monomer in the photocurable adhesive composition of the present invention is 50% by mass, and the preferable upper limit is 90% by mass. When the content ratio of the polymerizable monomer is within this range, the obtained cured product becomes excellent in adhesiveness and retention (creep resistance) to various base materials. A more preferable lower limit of the content ratio of the polymerizable monomer is 60% by mass, and a more preferable upper limit is 80% by mass.

[0035] The photocurable adhesive composition of the present invention contains a photoinitiator. The preferable lower limit of the weight average molecular weight of the above-mentioned photoinitiator is 500. By using a photoinitiator having a weight average molecular weight of 500 or more, the obtained photocurable adhesive composition becomes excellent in photocurability, adhesiveness, and retention (creep resistance) in the presence of oxygen. A more preferable lower limit of the weight average molecular weight of the photoinitiator is 800, a further preferable lower limit is 1000, and a particularly preferable lower limit is 1100. Also, from the viewpoints of solubility and handleability, the preferable upper limit of the weight average molecular weight of the photoinitiator is 10,000, and a more preferable upper limit is 5000. In this specification, the above-mentioned "weight average molecular weight" can be determined, for example, by measuring the molecular weight distribution in terms of polystyrene using gel permeation chromatography (GPC). Specifically, for example, it can be determined by measuring under the following conditions using gel permeation chromatography (manufactured by Waters, "2690 Separations Module", etc.). Solvent: Tetrahydrofuran Sample flow rate: 1 mL / min Detector: Differential refractive index system RI Column: GPC KF-806L (manufactured by Showa Denko KK) Column temperature (measurement temperature): 40°C Injection volume: 20 μL

[0036] The above photoinitiator is preferably a Norrish type I photoinitiator. By using the Norrish type I photoinitiator, the photocurable adhesive composition of the present invention becomes excellent in photocurability, adhesiveness, and retention (creep resistance) in the presence of oxygen. Among them, it is preferable that the above photoinitiator has two or more carbonyl groups contributing to the cleavage reaction of Norrish type I in one molecule.

[0037] Examples of the Norrish type I photoinitiator include polymers of ethyl (2,4,6 - trimethylbenzoyl)-phenylphosphinate, polyethylene glycol bis(β - 4(4-(2 - dimethylamino - 2 - benzyl)butanoyl)phenyl)piperazine propionate, bis(benzophenone - 2 - carboxylic acid) polyethylene glycol ester, 1 - hydroxycyclohexyl phenyl ketone, 2,4,6 - trimethylbenzoyl diphenylphosphine oxide, bis(2,4,6 - trimethylbenzoyl)phenylphosphine oxide, 2 - benzyl - 2-(dimethylamino)-4'-morpholinobutyrophenone, and the like.

[0038] Examples of commercially available Norrish type I photoinitiators include Omnipol TP, Omnipol 910, Omnirad TPO, Omnirad 369 (all manufactured by IGM Resins).

[0039] The preferable lower limit of the content of the above photoinitiator with respect to 100 parts by mass of the above polymerizable monomer is 0.5 parts by mass, and the preferable upper limit is 10 parts by mass. When the content of the above photoinitiator is within this range, the photocurable adhesive composition of the present invention becomes excellent in storage stability and photocurability. The more preferable lower limit of the content of the above photoinitiator is 0.7 parts by mass, and the more preferable upper limit is 9 parts by mass. The further preferable lower limit is 0.9 parts by mass, and the further preferable upper limit is 8 parts by mass.

[0040] The photocurable adhesive composition of the present invention contains a thermoplastic resin. By containing the above thermoplastic resin, the photocurable adhesive composition of the present invention becomes excellent in retention (creep resistance).

[0041] The thermoplastic resin described above preferably has a block structure or a graft structure. By including the thermoplastic resin having the block structure or the graft structure, the photocurable adhesive composition of the present invention exhibits superior retention (creep resistance). In particular, the thermoplastic resin preferably has a block structure, and more preferably has a block copolymer having hard segments and soft segments. 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. Furthermore, 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 will be treated as a thermoplastic resin having a block structure or a graft structure. An example of such a material is a (meth)acrylic triblock copolymer derived from three types of (meth)acrylic monomers.

[0042] The above thermoplastic resin preferably includes a thermoplastic resin having a structure derived from (meth)acrylate, and more preferably includes a thermoplastic resin having a structure derived from the monofunctional (meth)acrylic monomer according to the present invention. By including a thermoplastic resin having a structure derived from the monofunctional (meth)acrylic monomer according to the present invention, the resulting photocurable adhesive composition will have superior retention (creep resistance). Furthermore, from the viewpoint of enabling a higher content of bio-derived carbon, the thermoplastic resin preferably includes a thermoplastic resin having a structure derived from n-heptyl (meth)acrylate.

[0043] Examples of thermoplastic resins having a structure derived from the monofunctional (meth)acrylic monomer according to the present invention include a homopolymer or copolymer of the monofunctional (meth)acrylic monomer according to the present invention, a copolymer of the monofunctional (meth)acrylic monomer according to the present invention and styrene, a copolymer of the monofunctional (meth)acrylic monomer according to the present invention, styrene and acrylonitrile, and a copolymer of the monofunctional (meth)acrylic monomer according to the present invention and ethylene. Among these, a copolymer of the monofunctional (meth)acrylic monomer according to the present invention and styrene is preferred from the viewpoint of improving compatibility and retention (creep resistance) with the monofunctional (meth)acrylic monomer according to the present invention. The copolymer of the monofunctional (meth)acrylic monomer according to the present invention and styrene may have repeating structural units derived from other monomers. Examples of the other monomers include (meth)acrylic acid and other monofunctional (meth)acrylic monomers other than the monofunctional (meth)acrylic monomer according to the present invention.

[0044] The above thermoplastic resin has a preferred lower limit of 100,000 and a preferred upper limit of 1,000,000 in its weight-average molecular weight. Having the weight-average molecular weight of the above thermoplastic resin within this range results in a photocurable adhesive composition with superior retention (creep resistance). A more preferred lower limit of 150,000 and a more preferred upper limit of 500,000 in the weight-average molecular weight of the above thermoplastic resin is 150,000.

[0045] The lower limit of the content of the thermoplastic resin in 100 parts by mass of the photocurable adhesive composition of the present invention is 10 parts by mass, and the preferred upper limit is 60 parts by mass. Having the thermoplastic resin content within this range results in a photocurable adhesive composition with superior retention (creep resistance). A more preferred lower limit for the thermoplastic resin content is 15 parts by mass, and a more preferred upper limit is 50 parts by mass.

[0046] The photocurable adhesive composition of the present invention preferably further contains a tackifier. Examples of the tackifier include rosin-based resins and terpene-based resins.

[0047] Examples of the rosin-based resins mentioned above include rosin diols. 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 its molecule. Diols having a rosin component in their molecule are called rosin polyols, and these include polyether types, where the skeleton excluding the rosin component is polypropylene glycol (PPG), and polyester types, such as condensed polyester polyols, lactone polyester polyols, and polycarbonate diols. Examples of the rosin diols mentioned above 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. These can be produced by conventionally known methods.

[0048] Examples of the rosin components mentioned above 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 rosin obtained by hydrogenating these, and disproportionated rosin obtained by disproportionating these.

[0049] Examples of commercially available rosin-based resins include Pine Crystal KE-100, Pine Crystal KE-311, Pine Crystal KE-359, Pine Crystal KE-388, Pine Crystal KE-604, Pine Crystal KE-615-3, Pine Crystal KR-614, Pine Crystal D-6011, Pine Crystal D-6250, and Pencel D-135 (all manufactured by Arakawa Chemical Industries, Ltd.).

[0050] Examples of the terpene resins mentioned above include terpene phenol resins. These terpene phenol resins are copolymers of terpene resins, which are essential oil components obtained from natural products such as pine resin and orange peel, and phenol, and include fully hydrogenated terpene phenol resins and partially hydrogenated terpene phenol resins. Here, fully hydrogenated terpene phenol resins are terpene resins obtained by substantially completely hydrogenating the terpene phenol resins, and partially hydrogenated terpene phenol resins are terpene resins obtained by partially hydrogenating the terpene phenol resins. These terpene phenol resins have a double bond derived from terpenes and an aromatic ring double bond derived from phenols. Therefore, fully hydrogenated terpene phenol resins mean resins in which both the terpene and phenol parts are completely or almost hydrogenated, and partially hydrogenated terpene phenol resins mean resins in which the degree of hydrogenation of those parts is not complete but partial. The hydrogenation method and reaction form are not particularly limited. Examples of commercially available terpene phenol resins include YS Polystar G150 (manufactured by Yasuhara Chemical Co., Ltd.).

[0051] The preferred lower limit of the content of the tackifier in 100 parts by mass of the photocurable adhesive composition of the present invention is 5 parts by mass, and the preferred upper limit is 50 parts by mass. Having the tackifier content within this range results in a photocurable adhesive composition with superior adhesion to various substrates. A more preferred lower limit of the tackifier content is 10 parts by mass, and a more preferred upper limit is 40 parts by mass.

[0052] The photocurable adhesive composition of the present invention preferably contains 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, olefin polymer-based antifoaming agents, and the like.

[0053] The preferred lower limit for the content of the defoaming agent in 100 parts by mass of the photocurable adhesive composition of the present invention is 0.1 parts by mass, and the preferred upper limit is 3.0 parts by mass. Having the defoaming agent content within this range results in a photocurable adhesive composition with superior printability. A more preferred lower limit for the defoaming agent content is 0.5 parts by mass, and a more preferred upper limit is 2.0 parts by mass.

[0054] The photocurable adhesive composition of the present invention preferably further contains a leveling agent from the viewpoint of improving printability and the like. Examples of the leveling agent include silicone-based leveling agents, acrylic-based leveling agents, fluorine-based leveling agents, and the like.

[0055] The preferred lower limit for the content of the leveling agent in 100 parts by mass of the photocurable adhesive composition of the present invention is 0.05 parts by mass, and the preferred upper limit is 3.0 parts by mass. Having the leveling agent content within this range results in a photocurable adhesive composition with superior printability. A more preferred lower limit for the leveling agent content is 0.5 parts by mass, and a more preferred upper limit is 2.0 parts by mass.

[0056] The photocurable adhesive composition of the present invention may contain inorganic fillers from the viewpoint of improving coating properties and printability by adjusting viscosity. Examples of the inorganic fillers 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. Among these, silica is more preferred, and fumed silica is even more preferred.

[0057] The preferred lower limit for the content of the inorganic filler in 100 parts by mass of the photocurable adhesive composition of the present invention is 0.3 parts by mass, and the preferred upper limit is 7.0 parts by mass. Having the inorganic filler content within this range makes it easy to adjust the viscosity and other properties of the resulting photocurable adhesive composition while maintaining excellent adhesion. A more preferred lower limit for the inorganic filler content is 0.7 parts by mass, and a more preferred upper limit is 5.0 parts by mass.

[0058] The photocurable adhesive composition of the present invention may further contain various known additives such as organic fillers, plasticizers, silane coupling agents, sensitizers, thermosetting agents, curing retarders, antioxidants, storage stabilizers, and dispersants, to the extent that they do not hinder the objectives of the present invention.

[0059] The photocurable adhesive composition of the present invention may contain a crosslinking agent. On the other hand, from the viewpoint of reducing the burden on the environment and health, and from the viewpoint of printability, the photocurable adhesive composition of the present invention preferably does not contain an isocyanate-based crosslinking agent, and is particularly preferably the absence of an aromatic polyisocyanate having a structure derived from toluene diisocyanate.

[0060] The photocurable adhesive composition of the present invention contains no solvent, or the solvent content is greater than 0% by mass and less than or equal to 1% by mass. By containing no solvent, or having a solvent content greater than 0% by mass and less than or equal to 1%, the photocurable adhesive composition of the present invention can reduce the burden on the environment and health, and also exhibits excellent photocurability. In particular, it is most preferable that the photocurable adhesive composition of the present invention contains no solvent.

[0061] The preferred lower limit for the content of bio-derived carbon in the photocurable adhesive composition of the present invention is 10%. A bio-derived carbon content of 10% or more in the photocurable adhesive composition of the present invention is superior in terms of conserving petroleum resources and reducing carbon dioxide emissions, thereby reducing environmental impact. A more preferred lower limit for the bio-derived carbon content in the photocurable adhesive composition of the present invention is 40%. Furthermore, there is no particular preferred upper limit for the bio-derived carbon content in the photocurable adhesive composition of the present invention; it may be 100%. Note that bio-derived carbon contains a certain percentage of radioactive isotope (C-14), while petroleum-derived carbon contains almost no C-14. Therefore, the "bio-derived carbon content" as used herein can be calculated by measuring the concentration of C-14 contained in the photocurable adhesive composition or adhesive layer. Specifically, it can be measured according to ASTM D6866-22, a standard widely used in the bioplastics industry.

[0062] The content of bio-derived carbon in the photocurable adhesive composition of the present invention can be adjusted by changing each component constituting the photocurable adhesive composition of the present invention to a bio-derived material, and by changing the content of said bio-derived material. In particular, it is preferable to use a bio-derived material as the monofunctional (meth)acrylic monomer according to the present invention.

[0063] Methods for preparing the photocurable adhesive composition of the present invention include, for example, using a mixer to mix the polymerizable monomer, the photopolymerization initiator, the thermoplastic resin, and additives such as tackifiers as needed. Examples of such mixers include homodispers, homomixers, universal mixers, planetary mixers, kneaders, and three-roll mixers.

[0064] The photocurable adhesive composition of the present invention may be used as a material for forming the adhesive layer in adhesive tapes, but it is also suitably used in a method of direct printing onto an adherend. Forming an adhesive layer by coating an adherend (substrate) in a desired pattern by printing has the advantage of eliminating the cutting process, compared to obtaining an adhesive of a desired shape by cutting the adhesive tape immediately before bonding. As a result, it is possible to suppress the generation of waste and further reduce the environmental burden.

[0065] Methods for printing the light-curing adhesive composition of the present invention include, for example, gravure printing, flexographic printing, slot die coating, knife coating, inkjet printing, spray coating, spin coating, screen printing, stencil printing, and reverse offset printing. Among these, screen printing and inkjet printing are preferred.

[0066] When the photocurable adhesive composition of the present invention is used in screen printing, the preferred lower limit of the viscosity of the photocurable adhesive composition of the present invention, measured using an E-type viscometer at 25°C and 10 rpm, is 1 Pa·s, and the preferred upper limit is 400 Pa·s. Having a viscosity within this range makes the photocurable adhesive composition of the present invention more suitable for screen printing. When the photocurable adhesive composition of the present invention is used in screen printing, the more preferred lower limit of the viscosity is 5 Pa·s, and the more preferred upper limit is 100 Pa·s. Furthermore, when the photocurable adhesive composition of the present invention is used in inkjet printing, the preferred lower limit of the viscosity of the photocurable adhesive composition of the present invention, measured using an E-type viscometer at 25°C and 10 rpm, is 0.001 Pa·s, and the preferred upper limit is 10 Pa·s. Having a viscosity within this range makes the photocurable adhesive composition of the present invention more suitable for inkjet printing. When the photocurable adhesive composition of the present invention is used in inkjet printing, the more preferable lower limit of the viscosity is 0.005 Pa·s, and the more preferable upper limit is 1 Pa·s. As the E-type viscometer, for example, a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) can be used.

[0067] The photocurable adhesive composition of the present invention has a preferred lower limit of 1.05 and a preferred upper limit of 5.00 for its thixotropic index, which is the value obtained by dividing the viscosity measured at 25°C and 1 rpm using an E-type viscometer by the viscosity measured at 25°C and 10 rpm. Having the above thixotropic index within this range results in superior coating and printability for the photocurable adhesive composition of the present invention. A more preferred lower limit for the above thixotropic index is 1.10 and a more preferred upper limit is 3.00.

[0068] The photocurable adhesive composition of the present invention is applied to a substrate to a thickness of 50 μm, and without sealing the coated surface, is exposed to light in an atmospheric environment at a wavelength of 315 nm to 480 nm and an illuminance of 500 mW / cm². ２ The light, with an irradiation dose of 3000 mJ / cm² ２ The preferred lower limit of the gel fraction of the cured product obtained by irradiation in such a manner is 20% by mass, and the preferred upper limit is 70% by mass. When the gel fraction of the cured product is within the above range, the photocurable adhesive composition of the present invention exhibits superior adhesion and retention (creep resistance). A more preferred lower limit of the gel fraction of the cured product is 25% by mass, and a more preferred upper limit is 50% by mass. Note that the above "wavelength 315 nm to 480 nm" does not mean that the above-mentioned gel fraction of the cured product is satisfied across the entire wavelength range, but rather that there is a wavelength within that wavelength range that satisfies the above-mentioned gel fraction of the cured product.

[0069] The gel fraction of the cured product can be measured by following the procedure below. Specifically, first, the photocurable adhesive composition is coated onto a release PET film, which serves as the substrate, to a thickness of 50 μm. Then, without sealing the coated surface, the surface is irradiated in an atmospheric environment using a light irradiation device with a wavelength of 315 nm to 480 nm and an illuminance of 500 mW / cm². ２ The light was emitted at an intensity of 3000 mJ / cm². ２By irradiating the material in such a manner, the photocurable adhesive composition is cured to obtain a cured product. 0.15 g of the obtained cured product is weighed into a glass bottle, then immersed in 30 g of tetrahydrofuran and shaken at 23°C for 36 hours. Next, the cured product is removed through a 200-mesh filter and dried by heating at 110°C for 1 hour. After that, the mass of the cured product is measured, and the gel fraction can be calculated using the following formula: Gel fraction of cured product (mass%) = (W ２ / W １ ) × 100 W １ : Mass of the cured product before immersion in tetrahydrofuran at 23°C (W) ２ : Mass of the hardened product after immersion in tetrahydrofuran at 23°C, removal, and drying.

[0070] The photocurable adhesive composition of the present invention can form an adhesive layer by curing it by irradiation with light. Its use may involve forming the adhesive layer on a release film (separator) to create an adhesive tape transferable to an adherend, or forming the adhesive layer directly on the adherend. The method of forming the adhesive layer directly on the adherend minimizes the number of bonding steps and prevents air bubbles from forming at the interface during bonding. On the other hand, the method of forming the adhesive layer on a release film has the advantage of fewer construction constraints, as the adhesive layer is positioned on the adherend by transfer. A laminate having a cured product of the photocurable adhesive composition of the present invention and a release film on at least one side of the cured product is also part of the present invention.

[0071] An adhesive tape having an adhesive layer containing a cured product of the photocurable adhesive composition of the present invention is also one of the present inventions. The adhesive tape of the present invention may be a non-support type adhesive tape without a substrate, or it may be a support type adhesive tape, that is, an adhesive tape having a substrate and an adhesive layer containing a cured product of the photocurable adhesive composition of the present invention on at least one surface of the substrate.

[0072] If the adhesive tape of the present invention has a base material, it may be a single-sided adhesive tape having the adhesive layer on one side of the base material, or a double-sided adhesive tape having the adhesive layer on both sides of the base material.

[0073] Examples of the above-mentioned substrates include sheets made from resins such as acrylic resin, olefin resin, polycarbonate, polyvinyl chloride, ABS resin, polyethylene terephthalate (PET), nylon, polyurethane, and polyimide. Furthermore, the shape of the above-mentioned substrate is not particularly limited and may have a mesh-like structure or may have holes.

[0074] A method for manufacturing an adhesive tape, comprising the steps of coating a photocurable adhesive composition of the present invention onto a film, and irradiating the coated photocurable adhesive composition with light to form an adhesive layer, is also one of the present inventions. The film on which the photocurable adhesive composition of the present invention is coated may or may not be a release film.

[0075] According to the present invention, it is possible to provide a photocurable adhesive composition that can reduce the burden on the environment and health, and has excellent coating or printability, adhesion, and retention properties. Furthermore, according to the present invention, it is possible to provide laminates and adhesive tapes using the photocurable adhesive composition, as well as a method for manufacturing adhesive tapes using the photocurable adhesive composition.

[0076] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0077] (Synthesis Example 1 (Synthesis of n-hexyl acrylate containing bio-derived carbon)) Linoleic acid derived from castor oil was converted to linoleic acid hydroperoxide by lipoxygenase, and then a mixture containing n-hexylaldehyde was obtained by isomerase. By distillation of the obtained mixture, n-hexylaldehyde containing bio-derived carbon was obtained. Furthermore, by hydrogenation of the obtained n-hexylaldehyde containing bio-derived carbon, an n-hexyl alcohol containing bio-derived carbon was obtained. By esterifying the obtained n-hexyl alcohol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), n-hexyl acrylate containing bio-derived carbon was prepared.

[0078] (Synthesis Example 2 (Synthesis of n-heptyl acrylate containing bio-derived carbon)) Ricinoleic acid derived from castor oil was cracked to obtain a mixture containing undecylenic acid and n-heptyl alcohol. Then, undecylenic acid was separated from the obtained mixture by distillation to obtain n-heptyl alcohol containing bio-derived carbon. By esterifying the obtained n-heptyl alcohol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), n-heptyl acrylate containing bio-derived carbon was prepared.

[0079] (Synthesis Example 3 (Synthesis of 1-methylheptyl acrylate containing bio-derived carbon)) Ricinoleic acid derived from castor oil was dissolved in alkali to obtain a mixture containing sepacic acid and 1-methylheptyl alcohol. Next, sepacic acid was separated from the obtained mixture by distillation to obtain 1-methylheptyl alcohol containing bio-derived carbon. By esterifying the obtained 1-methylheptyl alcohol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 1-methylheptyl acrylate containing bio-derived carbon was prepared.

[0080] (Examples 1-13, Comparative Examples 1-3, 5) The materials were mixed in a planetary agitator (Sinky Co., Ltd., "Awatori Rentaro") according to the mixing ratios listed in Tables 1 and 2 to obtain the adhesive compositions of Examples 1-13 and Comparative Examples 1-3, 5.

[0081] (Comparative Example 4) Ethyl acetate was added to the reaction vessel as a polymerization solvent, and after bubbling with nitrogen, the reaction vessel was heated while introducing nitrogen to initiate reflux. Next, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile 10 times with ethyl acetate was added to the reaction vessel as a polymerization initiator, and 98.9 parts by mass of n-heptyl acrylate obtained in Synthesis Example 2, 1 part by mass of acrylic acid, and 0.1 parts by mass of 2-hydroxyethyl acrylate were added dropwise over 2 hours. After the dropwise addition was complete, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile 10 times with ethyl acetate was added again to the reaction vessel as a polymerization initiator, and the polymerization reaction was carried out for 4 hours to obtain a solution containing an acrylic copolymer (n-heptyl acrylate / acrylic acid / 2-hydroxyethyl acrylate copolymer). To the obtained acrylic copolymer-containing solution, 30 parts by mass of terpene phenol resin (Yasuhara Chemical Co., Ltd., "YS Polystar G150") was added per 100 parts by mass of acrylic copolymer. Furthermore, an isocyanate crosslinking agent (Covestro Corporation, "Desmodule L-75") was added so that the solid content was 0.5 parts by mass to prepare an adhesive composition.

[0082] The details of the materials listed in the table are as follows: (Monofunctional (meth)acrylic monomers) ・n-hexyl acrylate (n-hexyl acrylate containing bio-derived carbon obtained in Synthesis Example 1) ・n-heptyl acrylate (n-heptyl acrylate containing bio-derived carbon obtained in Synthesis Example 2) ・1-methylheptyl acrylate (1-methylheptyl acrylate containing bio-derived carbon obtained in Synthesis Example 3) ・n-butyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd., does not contain bio-derived carbon) ・lauryl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., does not contain bio-derived carbon) ・M-140: N-acryloyloxyethylhexahydrophthalimide (manufactured by Toagosei Co., Ltd., does not contain bio-derived carbon) ・Diethylacrylamide (manufactured by KJ Chemicals Co., Ltd., does not contain bio-derived carbon) (Polyfunctional (meth)acrylic monomers) ・UA-160™: Polyether-based polyfunctional urethane acrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd., does not contain bio-derived carbon) (Nitrogen-containing vinyl compound) ・CHMI: N-cyclohexylmaleimide (manufactured by Nippon Shokubai Co., Ltd., does not contain bio-derived carbon) (Photopolymerization initiator) ・Omnipol TP: ethyl (2,4,6-trimethylbenzoyl)-phenylphosphonate polymer (Norish type I photopolymerization initiator manufactured by IGM Resins, with a weight-average molecular weight of 1200, free of bio-derived carbon) (Thermoplastic resins) ・Thermoplastic resin A: Block copolymer having a styrene / acrylic acid / 2-hydroxyethyl acrylate copolymer structure as a hard segment and an n-butyl acrylate / methyl acrylate copolymer structure as a soft segment (hard segment ratio 20% by mass, weight-average molecular weight 320,000, free of bio-derived carbon) ・Thermoplastic resin B: Block copolymer having a styrene / acrylic acid / 2-hydroxyethyl acrylate copolymer structure as a hard segment and an n-heptyl acrylate / acrylic acid / methyl methacrylate copolymer structure as a soft segment (hard segment ratio 6.5% by mass, weight-average molecular weight 324,000, contains bio-derived carbon) ・Thermoplastic resin C: n-heptyl acrylate / acrylic acid / 2-hydroxyethyl acrylate copolymer (weight-average molecular weight 1,000,000, contains bio-derived carbon) (Tackifier)・D-135: Rosin resin (manufactured by Arakawa Chemical Industries, Ltd., contains bio-derived carbon) ・G150: Terpene phenol resin (manufactured by Yasuhara Chemical Co., Ltd., "YS Polystar G150", contains bio-derived carbon) (Inorganic filler) ・R805: Fumed silica (manufactured by Nippon Aerosil Co., Ltd., does not contain bio-derived carbon) (Defoaming agent) ・KS-66: Silicone-based defoaming agent (manufactured by Shin-Etsu Chemical Co., Ltd., does not contain bio-derived carbon) (Leveling agent) ・BYK-302: Silicone-based leveling agent (manufactured by Bic Chemie Japan, does not contain bio-derived carbon) (Isocyanate crosslinking agent) ・L-75: Isocyanate-based crosslinking agent (manufactured by Covestro, Inc., "Desmodule L-75", aromatic polyisocyanate having a structure derived from toluene diisocyanate, does not contain bio-derived carbon) (Solvent) ・Ethyl acetate (does not contain bio-derived carbon),

[0083] (Viscosity and Thixotropic Index) 0.4 mL of each of the obtained adhesive compositions was collected, and a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) was used as an E-type viscometer, and the viscosity was measured at 25 °C and 10 rpm using a cone plate of CP1. Also, the viscosity was measured under the conditions of 25 °C and 1 rpm, and the thixotropic index was calculated by dividing the viscosity measured under the conditions of 25 °C and 1 rpm by the viscosity measured under the conditions of 25 °C and 10 rpm. The results are shown in Tables 1 and 2.

[0084] (Gel Fraction of Cured Product) Each of the adhesive compositions obtained in Examples 1 to 13, Comparative Examples 1 to 3, and 5 was applied onto a release PET film (manufactured by Nippa Co., Ltd., "1-E", thickness 50 μm) using an applicator so that the thickness became 50 μm. Next, without sealing the coated upper surface, in an atmospheric environment, using a UV-LED irradiation device (manufactured by CCS Co., Ltd., "UVS01-01"), light with a wavelength of 365 nm and an illuminance of 500 mW / cm ２ was irradiated so that the irradiation dose became 3000 mJ / cm ２ to obtain a cured product. Then, the atmospheric surface of the cured product was sealed with a release PET film (manufactured by Nippa Co., Ltd., "1-C", thickness 38 μm) to obtain a laminate. Also, the adhesive composition obtained in Comparative Example 4 was applied onto a release PET film (manufactured by Nippa Co., Ltd., "1-E", thickness 50 μm) using an applicator so that the thickness after drying became 50 μm, and another release PET film (manufactured by Nippa Co., Ltd., "1-C", thickness 38 μm) was overlaid. Then, the adhesive composition was dried by heating at 110 °C for 5 minutes to obtain a laminate. Both release films were peeled off from each of the obtained laminates, 0.15 g of the cured product of the adhesive composition was weighed into a glass bottle, immersed in 30 g of tetrahydrofuran, and shaken and immersed at 23 °C for 36 hours. Next, the cured product was taken out through a 200-mesh filter, heated and dried at 110 °C for 1 hour. Then, the mass of the cured product was measured, and the gel fraction was calculated by the following formula. The results are shown in Tables 1 and 2. Gel fraction of cured product (mass %) = (W ２ / W １ ) × 100 W １ : Mass of the cured product before immersion in tetrahydrofuran at 23 °C W ２: Mass of the hardened product after immersion in tetrahydrofuran at 23°C, removal, and drying.

[0085] <Evaluation> The obtained adhesive compositions were evaluated as follows. The results are shown in Tables 1 and 2.

[0086] (Environmental and Health Impact) (1) Content of Bio-derived Carbon The content of bio-derived carbon in the obtained adhesive compositions was measured in accordance with ASTM D6866-21 and evaluated according to the following criteria. For the adhesive composition obtained in Comparative Example 1, the components excluding the solvent were evaluated. ○: When the content of bio-derived carbon was 10% or more ×: When the content of bio-derived carbon was less than 10%

[0087] (2) Amount of organic solvent emission The laminate obtained in the same manner as described above for "(gel fraction of cured product)" was cut to a size of 5 cm in length and 1 cm in width, both release PET films were peeled off, and one side of the cured adhesive composition was attached to aluminum foil to prepare a test specimen. The obtained test specimen was placed in a 21.5 mL vial and sealed tightly. Then, the vial containing the test specimen was heated at 80°C for 30 minutes using a headspace autosampler (Agilent Technologies, "Hewlett Packard 7694"), and 1.0 mL of the heated gas was injected into a gas chromatograph (Agilent Technologies, "Hewlett Packard 6890"). Toluene, ethyl acetate, and acetone were used as organic solvents, and the amount of organic solvent emitted per gram of test specimen (μg / g = ppm) was measured (the amount of organic solvent contained in the heated gas in the vial was calculated from the amount of organic solvent in 1.0 mL of heated gas, and this was converted to a value per gram of test specimen). The results were evaluated according to the following criteria: ○: Organic solvent emission was 500 ppm or less. ×: Organic solvent emission exceeded 500 ppm.

[0088] (Adhesion (180° Peel Adhesion)) Each adhesive composition obtained in Examples 1-13 and Comparative Examples 1-3 and 5 was coated onto the inner surface of an easily adhesive polyester film (Toyobo Co., Ltd., "Cosmoshine A4100") using an applicator to a thickness of approximately 50 μm. Subsequently, without sealing the coated surface, the film was irradiated in an atmospheric environment using a UV-LED irradiation device (CCS Corporation, "UVS01-01") at a wavelength of 365 nm and an irradiance of 500 mW / cm². ２ The light was emitted at an intensity of 3000 mJ / cm². ２ A cured product was obtained by irradiating it in such a manner. Next, the air surface was sealed with a release PET film (Nippa Co., Ltd., "1-C", thickness 38 μm), and a laminated film was prepared by cutting it to a width of 25 mm and a length of 200 mm (adhesion surface 25 mm x 125 mm). In addition, the adhesive composition obtained in Comparative Example 4 was coated onto the inner treated surface of an easy-to-adhere polyester film (Toyobo Co., Ltd., "Cosmoshine A4100") using an applicator to a thickness of 50 μm after drying, and then a release PET film (Nippa Co., Ltd., "1-C", thickness 38 μm) was placed on top. After that, the adhesive composition was dried by heating at 110°C for 5 minutes, and a laminated film was prepared by cutting it to a width of 25 mm and a length of 200 mm (adhesion surface 25 mm x 125 mm). The release PET film was peeled off each of the obtained laminated films, the exposed surface was bonded to a SUS substrate, and pressure was applied by passing a 2 kg roller back and forth once to obtain a test specimen. The obtained test specimens were cured in an environment of 25°C for 20 minutes, and then 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"). The adhesive strength was evaluated according to the following criteria: ○: 180° peel adhesive strength was 6 N / 25 mm or more ×: 180° peel adhesive strength was less than 6 N / 25 mm

[0089] (Retention (Creep resistance (1 kg load))) The laminate obtained in the same manner as in "(Gel fraction of cured material)" above was cut to 25 mm x 25 mm, one release PET film (1-C) was peeled off, and the cured adhesive composition was bonded to a mirror-polished SUS substrate with a width of 25 mm, a length of 100 mm, a thickness of 2 mm, and a 5 mm hole at the end of the long side. Next, the other release PET film (1-E) was peeled off, and the mirror-polished surface of the same SUS substrate was bonded to the exposed cured adhesive composition surface. Then, it was pressed at 215 N using a universal testing machine (A&D Corporation, "Tensilon RTI-1310"), left to stand for 24 hours in an environment of 25°C to obtain a test specimen. One of the obtained test specimens was suspended by hanging it on an S-hook, and a 1 kg weight was further suspended from the other SUS substrate. The material was left at 25°C, and the time it took for the weight to fall was measured. The retention capacity (creep resistance (1 kg load)) was evaluated according to the following criteria: ○: The weight did not fall after 24 hours. △: The time it took for the weight to fall was 6 hours or more but less than 24 hours. ×: The time it took for the weight to fall was less than 6 hours.

[0090] (Retention (Creep resistance (50g load))) The laminate obtained in the same manner as in "(Gel fraction of cured material)" above was cut to 20 mm x 60 mm, one release PET film (1-C) was peeled off, and a 23 μm thick PET film was backed on top. Next, the other release PET film (1-E) was peeled off, and a polycarbonate plate was placed on the exposed cured surface of the adhesive composition. A 2 kg rubber roller was moved back and forth once at a speed of 300 mm / min, and the polycarbonate plate was bonded to the tape made of the cured adhesive composition and PET film so that the bonding area was 20 mm x 50 mm. The polycarbonate plate used was one that had been washed with ethanol and then wiped dry. After that, a test piece was obtained by leaving it to stand for 24 hours in an environment of 25°C. A 50 g weight was suspended from the tape made of the cured adhesive composition and PET film in the obtained test piece in the 90° peel direction. The material was left at 25°C, and the time it took for the weight to fall was measured. The retention capacity (creep resistance (load 50g)) was evaluated according to the following criteria: ○: The weight did not fall after 3 hours. △: The time it took for the weight to fall was 1 hour or more but less than 3 hours. ×: The time it took for the weight to fall was less than 1 hour.

[0091] (Coating and Printability) (1) Coating Method (1-1) Applicator Coating Each adhesive composition obtained in Examples 1 to 13 and Comparative Examples 1 to 3 and 5 was coated onto a release PET film (Nipper Co., Ltd., "1-E", thickness 50 μm) using an applicator (Tester Sangyo Co., Ltd., "SA-201") to a thickness of approximately 50 μm. Then, a UV-LED irradiation device (CCS Co., Ltd., "UVS01-01") was used to irradiate the film at a wavelength of 365 nm and an irradiance of 500 mW / cm². ２ The light was emitted at an intensity of 3000 mJ / cm². ２A cured product was obtained by irradiating in such a manner. Furthermore, the adhesive composition obtained in Comparative Example 4 was coated onto a release PET film (Nipper Co., Ltd., "1-E", thickness 50 μm) using an applicator (Tester Sangyo Co., Ltd., "SA-201") so that the thickness after drying was approximately 50 μm. After that, the adhesive composition was dried at 110°C for 5 minutes to obtain a cured product. (1-2) Screen Printing The adhesive compositions obtained in Examples 1 to 13 and Comparative Examples 1 to 3 and 5 were screen printed using a screen printing machine (Micro-Tech Co., Ltd., "LABTOP 38") to coat a pattern onto the inner treated surface of an easy-to-adhere polyester film (Toyobo Co., Ltd., "Cosmoshine A4100") so that the thickness was approximately 50 μm. A patterned 80-mesh printing plate was used for the screen printing. Next, a UV-LED irradiation device (CCS Corporation, "UVS01-01") was used, with a wavelength of 365 nm and an illuminance of 500 mW / cm². ２ The light was emitted at an intensity of 3000 mJ / cm². ２ A cured product was obtained by irradiating the material in such a manner. Furthermore, the adhesive composition obtained in Comparative Example 4 was screen printed using a screen printing machine (Micro-Tech, "LABTOP 38") to coat a pattern onto the inner treated surface of an easy-to-adhere polyester film (Toyobo, "Cosmoshine A4100") so that the thickness after drying would be approximately 50 μm. A patterned 80-mesh printing plate was used for the screen printing. After that, the adhesive composition was dried at 110°C for 5 minutes to obtain a cured product. (1-3) Inkjet Printing The adhesive compositions obtained in Examples 1 to 13 and Comparative Examples 1 to 3 and 5 were coated onto a release PET film (Nippa, "1-E", 50 μm thick) using an inkjet device (Fujifilm, "Material Printer DMP-2831") so that the thickness would be approximately 2 μm. Next, a UV-LED irradiation device (CCS Corporation, "UVS01-01") was used, with a wavelength of 365 nm and an illuminance of 500 mW / cm². ２ The light was emitted at an intensity of 3000 mJ / cm². ２A cured product was obtained by irradiating the material in such a manner. Furthermore, the adhesive composition obtained in Comparative Example 4 was coated onto a release PET film (Nipper Co., Ltd. "1-E", thickness 50 μm) using an inkjet device (Fujifilm Corporation, "Material Printer DMP-2831") so that the thickness after drying was approximately 2 μm. Subsequently, a cured product was obtained by drying the adhesive composition at 110°C for 5 minutes.

[0092] (2) Evaluation of Coatability and Printability The cured product obtained was visually inspected and evaluated for coatability and printability according to the following criteria. ○: When a cured product with uniform thickness and a smooth surface was obtained. ×: When the thickness is uneven, or when irregularities or repellency occur on the surface. Note that if either evaluation result for coatability and printability is "○", it can be used without problems in that application. In addition, the adhesive composition obtained in Example 3 had less surface roughness (less irregularities) when printed compared to the adhesive composition obtained in Example 1.

[0093]

[0094]

[0095] According to the present invention, it is possible to provide a photocurable adhesive composition that can reduce the burden on the environment and health, and has excellent coating or printability, adhesion, and retention properties. Furthermore, according to the present invention, it is possible to provide laminates and adhesive tapes using the photocurable adhesive composition, as well as a method for manufacturing adhesive tapes using the photocurable adhesive composition.

Claims

1. A photocurable adhesive composition comprising a polymerizable monomer, a photopolymerization initiator, and a thermoplastic resin, wherein the polymerizable monomer comprises at least one monofunctional (meth)acrylic monomer selected from n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate, and the content of at least one monofunctional (meth)acrylic monomer selected from n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate in 100 parts by mass of the polymerizable monomer is 68 parts by mass or more, and the photocurable adhesive composition is characterized by not containing a solvent, or the solvent content being greater than 0% by mass and less than or equal to 1% by mass.

2. The photocurable adhesive composition according to claim 1, further comprising a tackifier.

3. The photocurable adhesive composition according to claim 1 or 2, wherein the thermoplastic resin comprises a thermoplastic resin having a structure derived from at least one monofunctional (meth)acrylic monomer selected from n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate.

4. The photocurable adhesive composition according to claim 3, wherein the thermoplastic resin comprises a thermoplastic resin having a structure derived from n-heptyl (meth)acrylate.

5. The photocurable adhesive composition according to claim 1, 2, 3, or 4, wherein the thermoplastic resin has a weight-average molecular weight of 100,000 or more and 1,000,000 or less.

6. The photocurable adhesive composition according to claim 1, 2, 3, 4, or 5, wherein the polymerizable monomer further contains a nitrogen-containing vinyl compound, and the content of the nitrogen-containing vinyl compound in 100 parts by mass of the polymerizable monomer is 0.5 parts by mass or more and 30 parts by mass or less.

7. The photocurable adhesive composition according to claim 1, 2, 3, 4, 5, or 6, wherein the photocurable adhesive composition does not contain an aromatic polyisocyanate having a structure derived from toluene diisocyanate.

8. The photocurable adhesive composition according to claim 1, 2, 3, 4, 5, 6, or 7, further comprising an antifoaming agent.

9. The photocurable adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, or 8, further comprising a leveling agent.

10. The photocurable adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9, further comprising an inorganic filler.

11. The photocurable adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the thixotropic index, which is the value obtained by dividing the viscosity measured using an E-type viscometer at 25°C and 1 rpm by the viscosity measured at 25°C and 10 rpm, is 1.05 or more and 5.00 or less.

12. A photocurable adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, used for printing.

13. The photocurable adhesive composition according to claim 12, which is used in screen printing and has a viscosity of 1 Pa·s or more and 400 Pa·s or less, as measured using an E-type viscometer at 25°C and 10 rpm.

14. The photocurable adhesive composition according to claim 12, which is used in inkjet printing and has a viscosity of 0.001 Pa·s or more and 10 Pa·s or less, as measured using an E-type viscometer at 25°C and 10 rpm.

15. A laminate having a cured product of a photocurable adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, and a release film on at least one side of the cured product.

16. An adhesive tape having an adhesive layer containing a cured product of the photocurable adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14.

17. A method for manufacturing an adhesive tape, comprising the steps of coating a photocurable adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 onto a film, and irradiating the coated photocurable adhesive composition with light to form an adhesive layer.

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