Adhesive agent composition, adhesive tape, and method for producing adhesive tape

Abstract

The present invention pertains to an adhesive agent composition comprising a (meth)acrylic monomer and a (meth)acrylic polymer. The (meth)acrylic monomer includes an alkyl(meth)acrylate having a branched alkyl group. The alkyl(meth)acrylate having a branched alkyl group includes a branched alkyl group-containing alkyl(meth)acrylate that has a glass transition temperature of -55°C to -15°C when formed into a homopolymer. The (meth)acrylic polymer has a structural unit derived from an alkyl(meth)acrylate. The adhesive agent composition contains an organic solvent and the content proportion of solvents in the adhesive agent composition is 10 mass% or less, or the adhesive agent composition does not contain an organic solvent.

Description

Adhesive composition, adhesive tape, and method for producing adhesive tape

[0001] The present invention relates to a pressure-sensitive adhesive composition. The present invention also relates to a pressure-sensitive adhesive tape. Furthermore, the present invention also relates to a method for producing a pressure-sensitive adhesive tape using the pressure-sensitive adhesive composition.

[0002] Conventionally, pressure-sensitive adhesive tapes having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive composition have been widely used to fix components in electronic devices, vehicles, houses, and building materials (e.g., Patent Documents 1 to 3). Specifically, for example, pressure-sensitive adhesive tapes are used to adhere a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to adhere a touch panel module to a display panel module.

[0003] JP 2015-052050 A JP 2015-021067 A JP 2015-120876 A

[0004] Acrylic adhesives containing acrylic copolymers are widely used as adhesives with excellent adhesive strength. Solvent coating methods and solventless coating methods are used to form adhesive layers containing acrylic adhesives. From the viewpoints of reducing environmental impact and volatile organic compounds (VOCs) remaining in the adhesive layer, solventless coating methods are preferred. Among the solventless coating methods, UV polymerization coating methods are widely used, and a method of performing heating after UV irradiation is also used to reduce volatile components (VOCs) such as solvents in the adhesive after curing with ultraviolet (UV) light.

[0005] On the other hand, examples of acrylic monomers that constitute the acrylic copolymer contained in acrylic pressure-sensitive adhesives include alkyl (meth)acrylates such as n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate. When an n-butyl (meth)acrylate-based pressure-sensitive adhesive with n-butyl (meth)acrylate as the main component is used, the cohesive strength of the pressure-sensitive adhesive increases and the shear adhesive strength increases, but the surface energy of such pressure-sensitive adhesives increases, resulting in poor adhesion to adherends (especially adherends with low surface energy). On the other hand, when 2-ethylhexyl (meth)acrylate with 2-ethylhexyl (meth)acrylate as the main component is used, 2-ethylhexyl (meth)acrylate has many methyl groups, which are low in polarity, so the surface energy of the pressure-sensitive adhesive decreases and it easily adheres to adherends. However, such pressure-sensitive adhesives have low cohesive strength.

[0006] An object of the present invention is to provide a pressure-sensitive adhesive composition that exhibits high shear adhesive strength and excellent adhesion to adherends, while also reducing the environmental impact. Another object of the present invention is to provide a pressure-sensitive adhesive tape that has high shear adhesive strength and excellent adhesion to adherends. A further object of the present invention is to provide a method for producing a pressure-sensitive adhesive tape using the pressure-sensitive adhesive composition.

[0007] Disclosure 1 relates to a pressure-sensitive adhesive composition containing a (meth)acrylic monomer and a (meth)acrylic polymer, wherein the (meth)acrylic monomer comprises an alkyl(meth)acrylate having a branched alkyl group, the alkyl(meth)acrylate having a branched alkyl group comprises a branched alkyl group-containing alkyl(meth)acrylate having a glass transition temperature of −55° C. or higher and −15° C. or lower when made into a homopolymer, the (meth)acrylic polymer has structural units derived from the alkyl(meth)acrylate, the pressure-sensitive adhesive composition contains an organic solvent, and the content of the organic solvent in the pressure-sensitive adhesive composition is 10 mass% or lower, or the pressure-sensitive adhesive composition is organic solvent-free. Disclosure 2 relates to the pressure-sensitive adhesive composition of Disclosure 1, wherein the branched alkyl group-containing alkyl(meth)acrylate having a glass transition temperature of −55° C. or higher and −15° C. or lower when made into a homopolymer contains 1-methylheptyl(meth)acrylate. Disclosure 3 is the pressure-sensitive adhesive composition of Disclosure 2, wherein the branched alkyl group-containing alkyl(meth)acrylate, which when converted into a homopolymer has a glass transition temperature of -55°C or higher and -15°C or lower, comprises an alkyl(meth)acrylate synthesized from an alkyl group-containing alcohol, which is a biologically derived material, and (meth)acrylic acid. Disclosure 4 is the pressure-sensitive adhesive composition of Disclosure 3, wherein the 1-methylheptyl(meth)acrylate comprises 1-methylheptyl(meth)acrylate synthesized from 1-methylheptyl alcohol, which is a biologically derived material, and (meth)acrylic acid. Disclosure 5 is the pressure-sensitive adhesive composition of Disclosure 1, 2, 3, or 4, wherein the (meth)acrylic monomer comprises a monomer having two or more (meth)acryloyl groups per molecule. Disclosure 6 is the pressure-sensitive adhesive composition of Disclosure 1, 2, 3, 4, or 5, wherein the (meth)acrylic monomer comprises a monomer having a crosslinkable functional group. Disclosure 7 is the pressure-sensitive adhesive composition of Disclosure 6, wherein the monomer having a crosslinkable functional group includes a hydroxyl group-containing monomer.Disclosure 8 is the pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, or 7, wherein the structural units derived from the alkyl (meth)acrylate in the (meth)acrylic polymer include structural units derived from an alkyl (meth)acrylate having a branched alkyl group, and the structural units derived from the alkyl (meth)acrylate having a branched alkyl group include structural units derived from a branched alkyl group-containing alkyl (meth)acrylate having a glass transition temperature of −55° C. or higher and −15° C. or lower when made into a homopolymer. Disclosure 9 is the pressure-sensitive adhesive composition of Disclosure 8, wherein the structural units derived from the branched alkyl group-containing alkyl (meth)acrylate having a glass transition temperature of −55° C. or higher and −15° C. or lower when made into a homopolymer include structural units derived from 1-methylheptyl (meth)acrylate.

[0023] Disclosure 10 relates to the pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein, in at least one of the cases where the (meth)acrylic monomer contains 1-methylheptyl(meth)acrylate and the (meth)acrylic polymer has a structural unit derived from 1-methylheptyl(meth)acrylate, the total content of the 1-methylheptyl(meth)acrylate and the structural unit derived from 1-methylheptyl(meth)acrylate in the (meth)acrylic polymer is 60 mass% or more in the total of the (meth)acrylic monomer and the (meth)acrylic polymer. Disclosure 11 relates to the pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the (meth)acrylic polymer has a structural unit derived from a monomer having a crosslinkable functional group. Disclosure 12 relates to the pressure-sensitive adhesive composition of Disclosure 11, wherein the structural unit derived from the monomer having a crosslinkable functional group includes a structural unit derived from a hydroxyl group-containing monomer.

[0023] Disclosure 13 is the pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, wherein, in at least one of the cases where the (meth)acrylic monomer contains a monomer having a crosslinkable functional group and the (meth)acrylic polymer contains a structural unit derived from the monomer having a crosslinkable functional group, the total content of the monomer having a crosslinkable functional group and the structural unit derived from the monomer having a crosslinkable functional group in the (meth)acrylic polymer is 0.01% by mass or more and 20% by mass or less in the total of the (meth)acrylic monomer and the (meth)acrylic polymer. Disclosure 14 is the pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, which contains a photopolymerization initiator. Disclosure 15 is the pressure-sensitive adhesive composition of Disclosure 14, wherein the photopolymerization initiator contains a compound having two or more photopolymerization reaction sites. Disclosure 16 is the PSA composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, which contains a tackifier resin. Disclosure 17 is the PSA composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16, which contains a crosslinking agent. Disclosure 18 is the PSA composition of Disclosure 17, wherein the crosslinking agent comprises at least one selected from the group consisting of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent. Disclosure 19 is the PSA composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18, which contains a pigment. The present disclosure 20 is the pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19, wherein the content of bio-derived carbon in the pressure-sensitive adhesive composition is 10% or more. The present disclosure 21 is a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20.Disclosure 22 is a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a (meth)acrylic copolymer having structural units derived from an alkyl (meth)acrylate having a branched alkyl group, wherein the structural units derived from the alkyl (meth)acrylate having a branched alkyl group comprise structural units derived from a branched alkyl group-containing alkyl (meth)acrylate having a glass transition temperature of −55° C. or higher and −15° C. or lower when made into a homopolymer. Disclosure 23 is the pressure-sensitive adhesive tape of Disclosure 22, wherein the structural units derived from the branched alkyl group-containing alkyl (meth)acrylate having a glass transition temperature of −55° C. or higher and −15° C. or lower when made into a homopolymer comprise structural units derived from 1-methylheptyl (meth)acrylate. Disclosure 24 is the pressure-sensitive adhesive tape of Disclosure 23, wherein the (meth)acrylic copolymer contains structural units derived from 1-methylheptyl (meth)acrylate in a proportion of 60 mass% or higher.

[0023] Disclosure 25 is the pressure-sensitive adhesive tape of Disclosures 21, 22, 23, or 24, wherein the pressure-sensitive adhesive layer does not contain an organic solvent, or wherein the pressure-sensitive adhesive layer contains an organic solvent and the content of the organic solvent in the pressure-sensitive adhesive layer is 5000 ppm or less. Disclosure 26 is the pressure-sensitive adhesive tape of Disclosures 21, 22, 23, 24, or 25, wherein the pressure-sensitive adhesive layer has a gel fraction of 10% by mass or more and 70% by mass or less. Disclosure 27 is the pressure-sensitive adhesive tape of Disclosures 21, 22, 23, 24, 25, or 26, which has a base layer. Disclosure 28 is the pressure-sensitive adhesive tape of Disclosures 21, 22, 23, 24, 25, 26, or 27, which is used for fixing electronic device components or in-vehicle components. Disclosure 29 is a method for producing a pressure-sensitive adhesive tape, comprising a step of curing the pressure-sensitive adhesive composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 by irradiating it with light. The present invention will be described in detail below. Hereinafter, one embodiment of the present invention will be described as "the present embodiment."

[0008] The present inventors investigated the possibility of incorporating a (meth)acrylic monomer into a pressure-sensitive adhesive composition containing a (meth)acrylic polymer, thereby enabling the formation of a pressure-sensitive adhesive layer even with a small amount of solvent in the pressure-sensitive adhesive composition, thereby reducing the environmental impact. Furthermore, they investigated incorporating a monomer of an alkyl (meth)acrylate having a branched alkyl group and a glass transition temperature within a specific range as the (meth)acrylic monomer in such a pressure-sensitive adhesive composition. As a result, they discovered that a pressure-sensitive adhesive composition can be obtained that exhibits high shear adhesive strength and excellent adhesion to adherends, while also reducing the environmental impact, leading to the completion of the present invention. The pressure-sensitive adhesive composition of this embodiment exhibits superior adhesion to adherends (especially low-polarity adherends) compared to n-butyl (meth)acrylate-based pressure-sensitive adhesive compositions, and exhibits higher shear adhesive strength compared to 2-ethylhexyl (meth)acrylate-based pressure-sensitive adhesive compositions. In this specification, the term "(meth)acrylic" refers to acrylic or methacrylic, and the term "(meth)acrylate" refers to acrylate or methacrylate. In addition, in this specification, "(meth)acrylic polymer" means a copolymer having a structural unit derived from (meth)acrylate contained in a pressure-sensitive adhesive composition before curing or before forming a pressure-sensitive adhesive layer or a pressure-sensitive adhesive.

[0009] The pressure-sensitive adhesive composition of the present embodiment contains a (meth)acrylic monomer. By containing the (meth)acrylic monomer in the pressure-sensitive adhesive composition of the present embodiment, curing of the pressure-sensitive adhesive composition of the present embodiment is facilitated. Furthermore, by containing the (meth)acrylic monomer in the pressure-sensitive adhesive composition of the present embodiment, the viscosity of the pressure-sensitive adhesive composition of the present embodiment is reduced, resulting in a pressure-sensitive adhesive composition that is easier to apply, and therefore the content of the solvent in the pressure-sensitive adhesive composition of the present embodiment can be reduced.

[0010] The (meth)acrylic monomer includes an alkyl(meth)acrylate having a branched alkyl group. The alkyl(meth)acrylate having a branched alkyl group includes a branched alkyl group-containing alkyl(meth)acrylate having a glass transition temperature (hereinafter sometimes simply referred to as "homopolymer Tg") when made into a homopolymer of -55°C or higher and -15°C or lower (hereinafter, the branched alkyl group-containing alkyl(meth)acrylate having a homopolymer Tg of -55°C or higher and -15°C or lower will also be referred to as "branched alkyl group-containing alkyl(meth)acrylate (A)"). When the alkyl(meth)acrylate having a branched alkyl group includes the branched alkyl group-containing alkyl(meth)acrylate (A), the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment can exhibit high shear adhesive strength and excellent adhesion to adherends. In this specification, the term "glass transition temperature when made into a homopolymer" refers to the glass transition temperature measured by differential scanning calorimetry of a homopolymer when the weight-average molecular weight of the alkyl (meth)acrylate is 100,000 or more and 2,000,000 or less. More specifically, the homopolymer Tg can be measured by performing the measurement in a nitrogen atmosphere (nitrogen flow, flow rate 50 mL / min) using a differential scanning calorimeter (manufactured by Seiko Instruments Inc., "220C" or the like) according to JIS K6240:2011, under conditions of a measurement temperature of -100°C to 200°C and a heating rate of 10°C / min.

[0011] The homopolymer Tg of the branched alkyl group-containing alkyl(meth)acrylate (A) is not particularly limited as long as it is −55° C. or higher and −15° C. or lower, with a preferred lower limit being −50° C. and a preferred upper limit being −25° C. When the homopolymer Tg of the branched alkyl group-containing alkyl(meth)acrylate (A) is within the above range, the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment can exhibit high shear adhesive strength and excellent adhesion to adherends. A more preferred lower limit of the homopolymer Tg of the branched alkyl group-containing alkyl(meth)acrylate (A) is −40° C.

[0012] Examples of the branched alkyl group-containing alkyl(meth)acrylate (A) include isobutyl acrylate (homopolymer Tg: -26°C), isoamyl acrylate (homopolymer Tg: -45°C), 1-methylheptyl acrylate (homopolymer Tg: -45°C), 1-methylheptyl methacrylate (homopolymer Tg: -25°C), isodecyl methacrylate (homopolymer Tg: -41°C), and isostearyl acrylate (homopolymer Tg: -18°C). Among these, the branched alkyl group-containing alkyl(meth)acrylate (A) preferably contains 1-methylheptyl(meth)acrylate. When the (meth)acrylic monomer contains 1-methylheptyl(meth)acrylate, it becomes easier to achieve both adhesion to the adherend and high cohesive strength.

[0013] The branched alkyl group-containing alkyl (meth)acrylate (A) may consist solely of petroleum-derived materials, but preferably contains a biologically-derived material. In recent years, the depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products have become a problem. Therefore, attempts have been made to conserve petroleum resources by using biologically-derived materials instead of petroleum-derived materials. The inclusion of a biologically-derived material in the branched alkyl group-containing alkyl (meth)acrylate (A) is preferable from the viewpoint of conserving petroleum resources. Furthermore, since biologically-derived materials are originally produced by absorbing carbon dioxide from the atmosphere, their combustion is thought to not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the viewpoint of reducing carbon dioxide emissions.

[0014] When the branched alkyl group-containing alkyl(meth)acrylate (A) contains a biological material, the branched alkyl group-containing alkyl(meth)acrylate (A) preferably contains an alkyl(meth)acrylate synthesized from a biologically derived alcohol and (meth)acrylic acid. In particular, 1-methylheptyl(meth)acrylate preferably contains 1-methylheptyl(meth)acrylate synthesized from 1-methylheptyl alcohol, a biologically derived material, and (meth)acrylic acid. A method for synthesizing 1-methylheptyl(meth)acrylate from 1-methylheptyl alcohol and (meth)acrylic acid includes, for example, esterifying n-hexyl(meth)acrylate with n-hexyl alcohol. A method for obtaining a biologically derived alcohol includes, for example, using a material collected from plants or animals (e.g., ricinoleic acid derived from castor oil) as a raw material, and distilling the resulting alkali-fused mixture to obtain 1-methylheptyl alcohol, a biologically derived material, inexpensively and easily.

[0015] The preferred lower limit of the content of the branched alkyl group-containing alkyl (meth)acrylate (A) per 100 parts by mass of the (meth)acrylic monomer is 20 parts by mass, and the preferred upper limit is 99 parts by mass. When the content of the branched alkyl group-containing alkyl (meth)acrylate (A) is within the above range, the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment have higher shear adhesive strength and better adhesion to the adherend. The more preferred lower limit of the content of the branched alkyl group-containing alkyl (meth)acrylate (A) is 40 parts by mass, more preferably 97 parts by mass, even more preferably 50 parts by mass, even more preferably 95 parts by mass, and even more preferably 60 parts by mass.

[0016] The preferred lower limit of the content of the 1-methylheptyl (meth)acrylate per 100 parts by mass of the (meth)acrylic monomer is 20 parts by mass, and the preferred upper limit is 99 parts by mass. When the content of the 1-methylheptyl (meth)acrylate is within the above range, the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment will have higher shear adhesive strength and better adhesion to an adherend. The more preferred lower limit of the content of the 1-methylheptyl (meth)acrylate is 30 parts by mass, the more preferred upper limit is 97 parts by mass, the even more preferred lower limit is 40 parts by mass, the even more preferred upper limit is 95 parts by mass, and the even more preferred lower limit is 60 parts by mass.

[0017] The (meth)acrylic monomer preferably contains a monomer having two or more (meth)acryloyl groups in one molecule. When the (meth)acrylic monomer contains a monomer having two or more (meth)acryloyl groups in one molecule, curing of the pressure-sensitive adhesive composition of the present embodiment proceeds more easily, and the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment have excellent cohesive strength and exhibit even better adhesive strength. Furthermore, having excellent cohesive strength further improves heat resistance and exhibits better retention performance at high temperatures. In this specification, the term "(meth)acryloyl" means acryloyl or methacryloyl.

[0018] Examples of the monomer having two or more (meth)acryloyl groups in one molecule include polyfunctional urethane (meth)acrylates, polyfunctional (meth)acrylic acid ester compounds, polyfunctional epoxy (meth)acrylates, etc. In this specification, the term "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound have reacted with (meth)acrylic acid.

[0019] 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.

[0020] Examples of the isocyanate compound that can be used as a raw material 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.

[0021] 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, tetraethylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

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

[0023] 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, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0024] 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.

[0025] The preferred lower limit of the content of the monomer having two or more (meth)acryloyl groups per molecule per 100 parts by mass of the (meth)acrylic monomer is 0.01 parts by mass, and the preferred upper limit is 10 parts by mass. When the content of the monomer having two or more (meth)acryloyl groups per molecule is 0.01 parts by mass or more, curing of the pressure-sensitive adhesive composition of the present embodiment proceeds more easily, and the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment have excellent cohesive strength and exhibit even better adhesive strength. In addition, the excellent cohesive strength further improves heat resistance and exhibits better retention performance at high temperatures. When the content of the monomer having two or more (meth)acryloyl groups per molecule is 10 parts by mass or less, the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment have reduced surface energy and therefore exhibit even better adhesion to adherends. The lower limit of the content of the monomer having two or more (meth)acryloyl groups in one molecule is more preferably 0.1 parts by mass, more preferably 8.0 parts by mass, even more preferably 0.5 parts by mass, even more preferably 5.0 parts by mass, still more preferably 2.0 parts by mass, and particularly preferably 1.0 parts by mass.

[0026] The (meth)acrylic monomer preferably contains a monomer having a crosslinkable functional group. When the (meth)acrylic monomer contains the monomer having a crosslinkable functional group, the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment have excellent cohesive strength and even better adhesive strength. Furthermore, the excellent cohesive strength further improves heat resistance and retention performance at high temperatures. Note that in this specification, the above-mentioned monomer having two or more (meth)acryloyl groups in one molecule is not considered to be the monomer having the crosslinkable functional group in the (meth)acrylic monomer.

[0027] Examples of the monomer having a crosslinkable functional group include a carboxy group-containing monomer, a hydroxy group-containing monomer, a glycidyl group-containing monomer, an amide group-containing monomer, a nitrile group-containing monomer, etc. Among these, the monomer having a crosslinkable functional group preferably includes at least one selected from the group consisting of a carboxy group-containing monomer and a hydroxy group-containing monomer, and more preferably includes a hydroxy group-containing monomer, because this makes it easier to adjust the degree of crosslinking of the pressure-sensitive adhesive composition of the present embodiment.

[0028] Examples of the carboxy group-containing monomer include (meth)acrylic acid. Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 1-methyl-2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1-methyl-2-hydroxypropyl (meth)acrylate, 1-methyl-3-hydroxypropyl (meth)acrylate, 1-ethyl-2-hydroxyethyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and 9-hydroxynonyl (meth)acrylate. Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate. Examples of the amide group-containing monomer include dimethyl(meth)acrylamide, isopropyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, etc. Examples of the nitrile group-containing monomer include (meth)acrylonitrile, etc.

[0029] The preferred lower limit of the content of the monomer having a crosslinkable functional group per 100 parts by mass of the (meth)acrylic monomer is 0.01 parts by mass, and the preferred upper limit is 20 parts by mass. When the content of the monomer having a crosslinkable functional group is 0.01 parts by mass or more, the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of this embodiment have excellent cohesion and exhibit even better adhesive strength. Furthermore, the excellent cohesion further improves heat resistance and exhibits better high-temperature retention performance. When the content of the monomer having a crosslinkable functional group is 20 parts by mass or less, the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of this embodiment have reduced surface energy and therefore exhibit better adhesion to the adherend. The more preferred lower limit of the content of the monomer having a crosslinkable functional group is 0.05 parts by mass, and the more preferred upper limit is 15 parts by mass, even more preferably 0.1 parts by mass, even more preferably 10 parts by mass, even more preferably 1.0 part by mass, and particularly preferably 3.0 parts by mass.

[0030] The (meth)acrylic monomer may contain other (meth)acrylic monomers other than the branched alkyl group-containing alkyl(meth)acrylate (A), the monomer having two or more (meth)acryloyl groups in one molecule, and the monomer having a crosslinkable functional group, as long as the object of the present invention is not impaired. Examples of the other (meth)acrylic monomers include alkyl(meth)acrylates having a linear alkyl group and branched alkyl group-containing alkyl(meth)acrylates other than the branched alkyl group-containing alkyl(meth)acrylate (A) (hereinafter, sometimes referred to as "branched alkyl group-containing alkyl(meth)acrylate (B)").

[0031] Examples of alkyl(meth)acrylates having a linear alkyl group include n-butyl acrylate (homopolymer Tg: −54° C.), n-butyl methacrylate (homopolymer Tg: 20° C.), n-hexyl acrylate (homopolymer Tg: −60° C.), n-hexyl methacrylate (homopolymer Tg: 0° C.), n-heptyl acrylate (homopolymer Tg: −63° C.), n-heptyl methacrylate (homopolymer Tg: −10° C.), n-octyl acrylate (homopolymer Tg: −65° C.), n-octyl methacrylate (homopolymer Tg: −18° C.), n-lauryl acrylate (homopolymer Tg: −3° C.), and n-lauryl methacrylate (homopolymer Tg: −35° C.).

[0032] Examples of the branched alkyl group-containing alkyl(meth)acrylate (B) include t-butyl acrylate (homopolymer Tg: 14°C), t-butyl methacrylate (homopolymer Tg: 107°C), and 2-ethylhexyl acrylate (homopolymer Tg: -70°C).

[0033] Examples of the other (meth)acrylic monomers include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and polypropylene glycol mono(meth)acrylate.

[0034] The pressure-sensitive adhesive composition of the present embodiment may contain other monomers besides the (meth)acrylic monomers, such as vinyl acetate, styrene, and bismaleimide, provided that the invention is not impaired.

[0035] The branched alkyl group-containing alkyl(meth)acrylate (A), the monomer having two or more (meth)acryloyl groups per molecule, the monomer having a crosslinkable functional group, and the other monomers are preferably acrylate monomers. By using an acrylate monomer, the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment can exhibit higher shear adhesive strength than when a methacrylate monomer is used.

[0036] The monomer having two or more (meth)acryloyl groups per molecule, the monomer having a crosslinkable functional group, and the other monomers preferably contain biologically derived materials, but may also consist solely of petroleum-derived materials. Theoretically, it is also possible for all of the (meth)acrylic monomers to be monomers containing biologically derived materials. From the standpoint of cost and productivity of the pressure-sensitive adhesive composition, a monomer containing a relatively inexpensive and easily available biologically derived material may be used, and this may be combined with a monomer consisting solely of petroleum-derived materials.

[0037] The preferred lower limit of the (meth)acrylic monomer content in the pressure-sensitive adhesive composition of this embodiment is 20% by mass, and the preferred upper limit is 95% by mass. By ensuring that the (meth)acrylic monomer content falls within this range, the pressure-sensitive adhesive composition of this embodiment can exhibit higher shear adhesive strength and superior adhesion to adherends. The more preferred lower limit of the (meth)acrylic monomer content is 30% by mass, and the more preferred upper limit is 80% by mass.

[0038] The pressure-sensitive adhesive composition of the present embodiment contains a (meth)acrylic polymer. The (meth)acrylic polymer has structural units derived from alkyl(meth)acrylate.

[0039] The structural unit derived from the alkyl(meth)acrylate preferably includes a structural unit derived from an alkyl(meth)acrylate having a branched alkyl group. The structural unit derived from the alkyl(meth)acrylate having a branched alkyl group preferably includes a structural unit derived from a branched alkyl group-containing alkyl(meth)acrylate having a glass transition temperature (hereinafter sometimes simply referred to as "homopolymer Tg") when made into a homopolymer of -55°C or higher and -15°C or lower (hereinafter, a structural unit derived from a branched alkyl group-containing alkyl(meth)acrylate having a homopolymer Tg of -55°C or higher and -15°C or lower may be referred to as a "structural unit derived from a branched alkyl group-containing alkyl(meth)acrylate (A)"). When the structural unit derived from the alkyl(meth)acrylate having a branched alkyl group includes a structural unit derived from the branched alkyl group-containing alkyl(meth)acrylate (A), the pressure-sensitive adhesive composition of the present embodiment can exhibit high shear adhesive strength and excellent adhesion to adherends.

[0040] The branched alkyl group-containing alkyl (meth)acrylate (A) contains a branched alkyl group, and therefore contains many methyl groups, which are low in polarity. Therefore, when the (meth)acrylic polymer contains structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A), the surface energy of the pressure-sensitive adhesive composition of this embodiment is reduced, thereby enabling the pressure-sensitive adhesive composition to exhibit excellent adhesion to an adherend. Furthermore, when the branched alkyl group-containing alkyl (meth)acrylate (A) is formed into a homopolymer, the glass transition temperature thereof is in a specific range of −55°C or higher and −15°C or lower. It is presumed that, when the branched alkyl group-containing alkyl (meth)acrylate (A) has a glass transition temperature in the specific range, a decrease in the cohesive strength of the pressure-sensitive adhesive composition can be suppressed when the (meth)acrylic polymer contains structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A). Furthermore, when the (meth)acrylic polymer has a structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A), the glass transition temperature of the (meth)acrylic polymer is appropriately reduced, and the storage modulus exhibited by the pressure-sensitive adhesive composition of the present embodiment is also appropriately reduced, which is presumably why the pressure-sensitive adhesive composition of the present embodiment can exhibit sufficient adhesion to an adherend.

[0041] The homopolymer Tg of the branched alkyl group-containing alkyl (meth)acrylate (A) in the structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) preferably has a lower limit of −50° C. and an upper limit of −25° C. When the homopolymer Tg of the branched alkyl group-containing alkyl (meth)acrylate (A) in the structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) is within the above range, the pressure-sensitive adhesive composition of the present embodiment can exhibit higher shear adhesive strength and better adhesion to adherends. A more preferred lower limit of the homopolymer Tg of the branched alkyl group-containing alkyl (meth)acrylate (A) in the structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) is −40° C.

[0042] Examples of the structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) include structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A) in the (meth)acrylic monomer described above. In particular, the structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) preferably includes a structural unit derived from 1-methylheptyl (meth)acrylate. When the (meth)acrylic polymer includes a structural unit derived from 1-methylheptyl (meth)acrylate, the pressure-sensitive adhesive composition of the present embodiment is more likely to achieve both high adhesion to an adherend and high cohesive strength.

[0043] The branched alkyl group-containing alkyl (meth)acrylate (A) in the structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) may consist solely of petroleum-derived materials, but preferably contains a biologically-derived material. In recent years, the depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products have become a concern. Therefore, attempts have been made to conserve petroleum resources by replacing petroleum-derived materials with biologically-derived materials. The branched alkyl group-containing alkyl (meth)acrylate (A) in the structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) containing a biologically-derived material is preferable from the perspective of conserving petroleum resources. Furthermore, since biologically-derived materials are originally produced by absorbing carbon dioxide from the atmosphere, their combustion is thought to not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the perspective of reducing carbon dioxide emissions.

[0044] When the branched alkyl group-containing alkyl (meth)acrylate (A) in the structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) contains a biological material, the branched alkyl group-containing alkyl (meth)acrylate (A) preferably contains an alkyl (meth)acrylate synthesized by esterifying an alcohol, which is a biological material, with (meth)acrylic acid. In particular, it is more preferable that the 1-methylheptyl (meth)acrylate contains 1-methylheptyl (meth)acrylate synthesized by esterifying 1-methylheptyl alcohol, which is a biological material, with (meth)acrylic acid. Examples of methods for obtaining biological alcohols include a method in which, using materials collected from plants and animals (e.g., ricinoleic acid derived from castor oil) as raw materials, the raw material is melted in an alkali and distilled to obtain 1-methylheptyl alcohol, which is a biological material, inexpensively and easily.

[0045] The preferred lower limit of the content of the structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A) in the (meth)acrylic polymer is 20% by mass, and the preferred upper limit is 99% by mass. When the content of the structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A) is within the above range, the pressure-sensitive adhesive composition of the present embodiment can exhibit higher shear adhesive strength and better adhesion to adherends. The more preferred lower limit of the content of the structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A) is 40% by mass, the more preferred upper limit is 97% by mass, the even more preferred lower limit is 50% by mass, and the even more preferred lower limit is 60% by mass. The content of the structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A) in the (meth)acrylic polymer can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy measurement ( １ H-NMR, １３ C-NMR, etc.) and calculation can be performed from the integrated intensity ratio of the hydrogen peak derived from the branched alkyl group-containing alkyl (meth)acrylate (A).

[0046] The preferred lower limit of the content of the structural units derived from 1-methylheptyl (meth)acrylate in the (meth)acrylic polymer is 20% by mass, and the preferred upper limit is 99% by mass. When the content of the structural units derived from 1-methylheptyl (meth)acrylate is within the above range, the pressure-sensitive adhesive composition of the present embodiment can exhibit higher shear adhesive strength and better adhesion to adherends. The more preferred lower limit of the content of the structural units derived from 1-methylheptyl (meth)acrylate is 30% by mass, the more preferred upper limit is 97% by mass, the even more preferred lower limit is 50% by mass, and the even more preferred lower limit is 60% by mass. The content of the structural units derived from 1-methylheptyl (meth)acrylate in the (meth)acrylic polymer can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy measurement ( １ H-NMR, １３ The amount of hydrogen can be calculated from the integrated intensity ratio of the peak of hydrogen derived from the 1-methylheptyl (meth)acrylate by performing spectroscopy (e.g., C-NMR) and the like.

[0047] In at least one of the cases where the (meth)acrylic monomer contains 1-methylheptyl acrylate and where the (meth)acrylic polymer has a structural unit derived from 1-methylheptyl acrylate, the pressure-sensitive adhesive composition of the present embodiment has a preferred lower limit of 60 mass% for the total content of the 1-methylheptyl (meth)acrylate and the structural unit derived from 1-methylheptyl (meth)acrylate in the (meth)acrylic polymer in the total of the (meth)acrylic monomer and the (meth)acrylic polymer (hereinafter, sometimes simply referred to as the "total content of 1-methylheptyl (meth)acrylate components"). When the total content of the 1-methylheptyl (meth)acrylate components is 60 mass% or more, the pressure-sensitive adhesive composition of the present embodiment can exhibit higher shear adhesive strength and better adhesion to adherends. A more preferred lower limit for the total content of the 1-methylheptyl (meth)acrylate components is 70 mass%, and an even more preferred lower limit is 80 mass%. Furthermore, the preferred upper limit of the total content of the 1-methylheptyl (meth)acrylate component is 99% by mass. When the total content of the 1-methylheptyl (meth)acrylate component is 99% by mass or less, the pressure-sensitive adhesive composition of this embodiment exhibits superior adhesive strength. The more preferred upper limit of the total content of the 1-methylheptyl (meth)acrylate component is 97% by mass, and even more preferred upper limit is 95% by mass. Note that when the (meth)acrylic monomer does not contain 1-methylheptyl (meth)acrylate, or when the (meth)acrylic polymer does not have a structural unit derived from 1-methylheptyl (meth)acrylate, the total content of the 1-methylheptyl (meth)acrylate component refers to the content of only one of the components.

[0048] The (meth)acrylic polymer preferably has a structural unit derived from a monomer having a crosslinkable functional group. When the (meth)acrylic polymer has a structural unit derived from the monomer having a crosslinkable functional group, the pressure-sensitive adhesive composition of the present embodiment can exhibit excellent cohesive strength, thereby exhibiting even more excellent adhesive strength. Furthermore, the excellent cohesive strength further improves heat resistance, thereby exhibiting even better retention performance at high temperatures.

[0049] Examples of the structural unit derived from the monomer having a crosslinkable functional group include a structural unit derived from a carboxy group-containing monomer, a structural unit derived from a hydroxy group-containing monomer, a structural unit derived from a glycidyl group-containing monomer, a structural unit derived from an amide group-containing monomer, and a structural unit derived from a nitrile group-containing monomer. Among these, since this facilitates the adjustment of the degree of crosslinking of the pressure-sensitive adhesive composition of the present embodiment, it is preferred that the structural unit derived from the monomer having a crosslinkable functional group comprises at least one structural unit selected from the group consisting of a structural unit derived from a carboxy group-containing monomer and a structural unit derived from a hydroxy group-containing monomer. Furthermore, it is preferred that the monomer having a crosslinkable functional group in the structural unit derived from the monomer having a crosslinkable functional group has a (meth)acryloyl group.

[0050] Examples of the structural units derived from the carboxy group-containing monomer include structural units derived from the carboxy group-containing monomer in the (meth)acrylic monomer described above. Examples of the structural units derived from the hydroxy group-containing monomer include structural units derived from the hydroxy group-containing monomer in the (meth)acrylic monomer described above. Examples of the structural units derived from the glycidyl group-containing monomer include structural units derived from the glycidyl group-containing monomer in the (meth)acrylic monomer described above. Examples of the structural units derived from the amide group-containing monomer include structural units derived from the amide group-containing monomer in the (meth)acrylic monomer described above. Examples of the structural units derived from the nitrile group-containing monomer include structural units derived from the nitrile group-containing monomer in the (meth)acrylic monomer described above.

[0051] The content of the structural unit derived from the monomer having a crosslinkable functional group in the (meth)acrylic polymer is preferably 0.01% by mass or more and less than 20% by mass. When the content of the structural unit derived from the monomer having a crosslinkable functional group is 0.01% by mass or more, the pressure-sensitive adhesive composition of the present embodiment can exhibit excellent cohesive strength, thereby exhibiting even better adhesive strength. Furthermore, the excellent cohesive strength further improves heat resistance, allowing the pressure-sensitive adhesive composition of the present embodiment to exhibit better retention performance at high temperatures. When the content of the structural unit derived from the monomer having a crosslinkable functional group is less than 20% by mass, the polarity of the (meth)acrylic polymer is reduced, thereby reducing the surface energy of the pressure-sensitive adhesive composition of the present embodiment, thereby allowing the pressure-sensitive adhesive composition to exhibit even better adhesion to an adherend. The lower limit of the content of the structural unit derived from the monomer having a crosslinkable functional group is more preferably 0.05% by mass, and more preferably 15% by mass, with an even more preferred lower limit being 3.0% by mass and an even more preferred upper limit being 10% by mass. The content of the structural unit derived from the monomer having a crosslinkable functional group in the (meth)acrylic polymer can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy of the (meth)acrylic polymer ( １ H-NMR, １３C-NMR, etc.) and calculation can be performed from the integrated intensity ratio of the hydrogen peak derived from the monomer having the crosslinkable functional group.

[0052] In at least one of the cases where the (meth)acrylic monomer contains a monomer having a crosslinkable functional group and the (meth)acrylic polymer contains a structural unit derived from the monomer having a crosslinkable functional group, the pressure-sensitive adhesive composition of the present embodiment has a preferred lower limit of 0.01% by mass and an upper limit of 20% by mass for the total content of the monomer having a crosslinkable functional group and the structural unit derived from the monomer having a crosslinkable functional group in the (meth)acrylic polymer in the total of the (meth)acrylic monomer and the (meth)acrylic polymer (hereinafter simply referred to as the "total content ratio of monomer components having a crosslinkable functional group"). By having a total content ratio of the monomer components having a crosslinkable functional group of 0.01% by mass or more, the pressure-sensitive adhesive composition of the present embodiment can exhibit excellent cohesive strength, thereby exhibiting even better adhesive strength. Furthermore, the excellent cohesive strength further improves heat resistance and allows for better retention at high temperatures. When the content of the structural unit derived from the monomer having a crosslinkable functional group is 20% by mass or less, the polarity of the (meth)acrylic polymer decreases, thereby reducing the surface energy of the pressure-sensitive adhesive composition of this embodiment, thereby enabling the pressure-sensitive adhesive composition to exhibit better adhesion to an adherend. The lower limit of the total content of the monomer components having a crosslinkable functional group is more preferably 0.05% by mass, more preferably 15% by mass, even more preferably 0.1% by mass, even more preferably 10% by mass, even more preferably 1.0% by mass, and particularly preferably 3.0% by mass. Note that when the (meth)acrylic monomer does not contain the monomer having a crosslinkable functional group, or when the (meth)acrylic polymer does not contain a structural unit derived from the monomer having a crosslinkable functional group, the total content of the monomer components having a crosslinkable functional group refers to only one of the content rates.

[0053] The (meth)acrylic polymer may have a constituent unit derived from a monomer other than the constituent unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) and the constituent unit derived from the monomer having a crosslinkable functional group, within the scope of not impairing the object of the present invention.

[0054] Examples of the structural units derived from the other monomers include structural units derived from monomers such as cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, polypropylene glycol mono(meth)acrylate, etc. Furthermore, examples of the structural units derived from the other monomers include structural units derived from various monomers that are commonly used as raw materials for (meth)acrylic polymers, such as vinyl acetate and styrene.

[0055] The structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A), the structural units derived from the monomer having a crosslinkable functional group, and the structural units derived from the other monomers are preferably structural units derived from acrylate monomers. When the structural units derived from the branched alkyl group-containing alkyl (meth)acrylate (A), the structural units derived from the monomer having a crosslinkable functional group, and the structural units derived from the other monomers are structural units derived from acrylate monomers, the weight-average molecular weight of the (meth)acrylic polymer contained in the pressure-sensitive adhesive composition of this embodiment can be easily increased, compared to when the structural units are derived from methacrylate monomers, and higher shear adhesive strength can be exhibited.

[0056] The monomer having a crosslinkable functional group and the other monomer preferably contain a biologically-derived material, but may also consist solely of petroleum-derived materials. Theoretically, it is also possible for all of the acrylic monomers constituting the (meth)acrylic polymer to be monomers containing biologically-derived materials. From the standpoint of cost and productivity of the pressure-sensitive adhesive composition, a monomer containing a relatively inexpensive and easily available biologically-derived material may be used, and this may be combined with a monomer consisting solely of petroleum-derived materials.

[0057] The preferred lower limit of the weight-average molecular weight of the (meth)acrylic polymer is 100,000, and the preferred upper limit is 2,000,000. When the weight-average molecular weight of the (meth)acrylic polymer is 100,000 or more, the pressure-sensitive adhesive composition of the present embodiment can exhibit excellent cohesive strength, thereby exhibiting even more excellent adhesive strength. Furthermore, the excellent cohesive strength further improves heat resistance, thereby enabling the pressure-sensitive adhesive composition of the present embodiment to exhibit even better retention performance at high temperatures. When the weight-average molecular weight of the (meth)acrylic polymer is 2,000,000 or less, the viscosity of the pressure-sensitive adhesive composition of the present embodiment is reduced, thereby enabling the pressure-sensitive adhesive composition to exhibit even better adhesion to the adherend. The more preferred lower limit of the weight-average molecular weight of the (meth)acrylic polymer is 300,000, the more preferred upper limit is 1,500,000, and the even more preferred upper limit is 1,000,000. In this specification, the weight-average molecular weight is the weight-average molecular weight converted into standard polystyrene by GPC (gel permeation chromatography) measurement. Specifically, a (meth)acrylic polymer is diluted 50 times with tetrahydrofuran (THF), and the resulting diluted solution is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare a measurement sample. Next, this measurement sample is supplied to a gel permeation chromatograph, and GPC measurement is performed under conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-equivalent molecular weight of the (meth)acrylic polymer is measured, and this value is taken as the weight-average molecular weight of the (meth)acrylic polymer. Examples of the gel permeation chromatograph include the 2690 Separations Module (manufactured by Waters Corporation).

[0058] The (meth)acrylic polymer can be obtained by polymerizing a mixture of constituent monomers as raw materials through a radical reaction in the presence of a polymerization initiator. Examples of the radical reaction include living radical polymerization and free radical polymerization. Living radical polymerization produces copolymers with more uniform molecular weight and composition than free radical polymerization, and can suppress the generation of low-molecular-weight components, etc., resulting in a pressure-sensitive adhesive composition that exhibits stronger cohesive strength and therefore better adhesion to the adherend. Conventional methods can be used to polymerize the monomer mixture, including solution polymerization (boiling point polymerization or constant temperature polymerization), UV polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization. Among these, solution polymerization and UV polymerization are preferred because they result in a pressure-sensitive adhesive composition that exhibits better adhesion to the adherend. When solution polymerization is used to polymerize the monomer mixture, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, dimethyl sulfoxide, ethanol, acetone, and diethyl ether.

[0059] Examples of methods for adjusting the weight average molecular weight of the (meth)acrylic polymer include a method of changing the type or amount of a polymerization initiator or the monomer concentration during the polymerization reaction, a method of adding a small amount of a chain transfer agent such as dodecyl mercaptan, a method of changing the type of polymerization reaction solvent to control chain transfer to the solvent, and a method of changing the temperature and time during the reaction.

[0060] Examples of the polymerization initiator used for synthesizing the (meth)acrylic polymer include organic peroxides and azo compounds. Examples of the organic peroxides include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of the azo compounds include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. Furthermore, when the radical reaction is performed by living radical polymerization, examples of the polymerization initiator include organotellurium polymerization initiators. The organotellurium polymerization initiator is not particularly limited as long as it is one that is commonly used in living radical polymerization, and examples thereof include organotellurium compounds, organotelluride compounds, etc. In addition to the organotellurium polymerization initiator, an azo compound may also be used as the polymerization initiator in the living radical polymerization in order to accelerate the polymerization rate.

[0061] The glass transition temperature of the (meth)acrylic polymer preferably has a lower limit of −55° C. and an upper limit of −15° C. When the glass transition temperature of the (meth)acrylic polymer is within the above range, the pressure-sensitive adhesive composition of the present embodiment can exhibit higher shear adhesive strength and better adhesion to adherends. The lower limit of the glass transition temperature of the (meth)acrylic polymer is more preferably −45° C. and the upper limit is more preferably −25° C. The glass transition temperature of the (meth)acrylic polymer can be measured by the same method as for the homopolymer Tg described above.

[0062] The preferred lower limit of the (meth)acrylic polymer content in the pressure-sensitive adhesive composition of this embodiment is 5% by mass, and the preferred upper limit is 80% by mass. By ensuring that the (meth)acrylic polymer content is within this range, the pressure-sensitive adhesive composition of this embodiment can exhibit higher shear adhesive strength and superior adhesion to the adherend. The more preferred lower limit of the (meth)acrylic polymer content is 20% by mass, and the more preferred upper limit is 70% by mass.

[0063] The pressure-sensitive adhesive composition of the present embodiment contains an organic solvent, and the upper limit of the organic solvent content in the pressure-sensitive adhesive composition of the present embodiment is 10% by mass, or the pressure-sensitive adhesive composition of the present embodiment is free of organic solvent. The pressure-sensitive adhesive composition of the present embodiment contains an organic solvent, and the organic solvent content in the pressure-sensitive adhesive composition of the present embodiment is 10% by mass or less, or the pressure-sensitive adhesive composition of the present embodiment is free of organic solvent. This reduces the environmental impact during the production of the pressure-sensitive adhesive composition of the present embodiment, as well as the environmental impact caused by volatile organic compounds (VOCs) remaining in the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment. When the pressure-sensitive adhesive composition of the present embodiment contains an organic solvent, the upper limit of the organic solvent content is preferably 6.5% by mass, more preferably 5% by mass, and even more preferably 1% by mass. It is most preferred that the pressure-sensitive adhesive composition of the present embodiment is free of organic solvent. The organic solvent content in the pressure-sensitive adhesive composition of the present embodiment can be measured by gas chromatography-mass spectrometry (GC-MS). Specifically, the solvent contained in the pressure-sensitive adhesive layer is identified, and then the pressure-sensitive adhesive composition is diluted with chloroform using the solvent as a standard sample with a known content, and gas chromatography mass spectrometry (GC-MS) of the measurement sample is performed. A calibration curve is created from the measured peak areas, and the created calibration curve is used to calculate the solvent content. The measurement conditions for gas chromatography mass spectrometry are, for example, as follows. <GC-MS Measurement Conditions> Gas chromatograph mass spectrometer: JMS Q1500 (manufactured by JEOL Ltd.) Mobile phase: helium Helium flow rate: 1.0 mL / min Detector: quadrupole mass spectrometer Ionization method: EI method Column: SLB-5ms capillary GC column (manufactured by Sigma-Aldrich) Inlet temperature: 320°C Column temperature: 40°C to 340°C Injection volume: 1.0 μL

[0064] Methods for adjusting the content ratio of the organic solvent in the adhesive composition of this embodiment include, for example, a method of reducing the amount of organic solvent used in synthesizing the (meth)acrylic polymer, a method of removing the organic solvent after synthesizing the (meth)acrylic polymer, and the like.

[0065] When the pressure-sensitive adhesive composition of the present embodiment contains a solvent, the solvent is not particularly limited, and water, an organic solvent, a mixed solvent of water and an organic solvent, etc. can be used. However, from the viewpoint of further reducing the environmental load caused by volatile organic compounds (VOCs) remaining in the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of the present embodiment, it is preferable that the content of the organic solvent is as small as possible, as described above.

[0066] The pressure-sensitive adhesive composition of the present embodiment preferably contains a polymerization initiator. By containing the polymerization initiator in the pressure-sensitive adhesive composition of the present embodiment, curing of the pressure-sensitive adhesive composition of the present embodiment is more likely to proceed. From the viewpoint of storage stability, etc., the polymerization initiator may be blended into the pressure-sensitive adhesive composition of the present embodiment immediately before curing the pressure-sensitive adhesive composition.

[0067] The polymerization initiator may be a photopolymerization initiator or a thermal polymerization initiator, but from the viewpoint of reducing the energy required for curing, a photopolymerization initiator is preferred.

[0068] Examples of the photopolymerization initiator include acetophenone derivatives such as alkylphenone compounds, benzoin ether compounds, ketal derivatives, phosphine oxide derivatives such as acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, etc. Among these, acetophenone derivatives and phosphine oxide derivatives are preferred from the viewpoints of adjusting the gel fraction of the pressure-sensitive adhesive layer described below and improving the reaction rate of the monomer to be polymerized, thereby facilitating the polymerization reaction.

[0069] Examples of the acetophenone derivatives include methoxyacetophenone, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)butan-1-one. Examples of the benzoin ether compounds include benzoin propyl ether and benzoin isobutyl ether. Examples of the ketal derivatives include benzyl dimethyl ketal and acetophenone diethyl ketal. Examples of the phosphine oxide derivatives include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. Examples of the titanocene compounds include bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanocene. Examples of the oxime ester compound include 1-(O-acetyloxime)-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone and 1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime)-1,2-octadione. Examples of the thioxanthone compound include 2-isopropylthioxanthone. Examples of the photopolymerization initiator include bis(η5-cyclopentadienyl)titanocene derivative compounds, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, α-hydroxycyclohexylphenyl ketone, and 2-hydroxymethylphenylpropane. These photopolymerization initiators may be used alone or in combination of two or more.

[0070] The photopolymerization initiator preferably contains a compound having two or more photopolymerization reaction sites. When the photopolymerization initiator contains a compound having two or more photopolymerization reaction sites, the curing of the pressure-sensitive adhesive composition of the present invention is more likely to proceed. Examples of the compound having two or more photopolymerization reaction sites include Omnipol TP (manufactured by IGM Resins) and Omnipol 910 (manufactured by IGM Resins). In this specification, the term "photopolymerization reaction site" refers to the structure of a carbonyl group that contributes to a Norrish type I cleavage reaction or a carbonyl group that contributes to a Norrish type II hydrogen abstraction reaction.

[0071] Examples of the thermal polymerization initiator include organic peroxide-based thermal polymerization initiators, etc. Commercially available examples of the organic peroxide-based thermal polymerization initiator include Perbutyl H and Percumyl H (both manufactured by NOF Corporation).

[0072] The content of the polymerization initiator is preferably 0.01 parts by mass at the lower limit and 10 parts by mass at the upper limit, relative to 100 parts by mass of the total of the (meth)acrylic monomer and the (meth)acrylic polymer. By having the content of the polymerization initiator within this range, the curing of the pressure-sensitive adhesive composition of this embodiment proceeds more easily, and the pressure-sensitive adhesive and pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive composition of this embodiment have appropriate flexibility and exhibit superior adhesion to the adherend. The lower limit of the content of the polymerization initiator is more preferably 0.1 parts by mass, the upper limit is more preferably 5.0 parts by mass, and the upper limit is even more preferably 1.0 part by mass.

[0073] The pressure-sensitive adhesive composition of the present embodiment preferably contains a tackifier resin. When the pressure-sensitive adhesive composition of the present embodiment contains a tackifier resin, it can exhibit even better adhesive strength.

[0074] The tackifier resin is not particularly limited, and examples thereof include rosin ester tackifier resins, terpene tackifier resins, coumarone-indene tackifier resins, alicyclic saturated hydrocarbon tackifier resins, C5 petroleum tackifier resins, C9 petroleum tackifier resins, and C5-C9 copolymer petroleum tackifier resins. These tackifier resins may be used alone or in combination of two or more. Among these, it is preferable to use at least one selected from the group consisting of rosin ester tackifier resins and terpene tackifier resins.

[0075] Examples of the rosin ester-based tackifying resin include polymerized rosin ester-based resins and hydrogenated rosin ester-based resins. Examples of the terpene-based tackifying resin include terpene-based resins and terpene phenol-based resins. The rosin ester-based tackifying resins and terpene-based tackifying resins are preferably derived from living organisms. Examples of the rosin ester-based tackifying resins derived from living organisms include rosin ester-based tackifying resins derived from natural resins such as pine resin. Examples of the terpene-based tackifying resins derived from living organisms include terpene-based tackifying resins derived from plant essential oils.

[0076] Specific examples of the rosin ester-based tackifying resin include Pencel D-135, Pine Crystal KE-359, Ester Gum AA-V, and Ester Gum H (all manufactured by Arakawa Chemical Industries, Ltd.). Specific examples of the terpene-based tackifying resin include YS Resin PX1250 and YS Polystar G150 (all manufactured by Yasuhara Chemical Co., Ltd.).

[0077] In the pressure-sensitive adhesive composition of this embodiment, the preferred lower limit of the content of the tackifier resin relative to 100 parts by mass of the total of the (meth)acrylic monomer and the (meth)acrylic polymer is 10 parts by mass, and the preferred upper limit is 50 parts by mass. When the content of the tackifier resin is 10 parts by mass or more, the pressure-sensitive adhesive composition of this embodiment can exhibit superior adhesive strength. When the content of the tackifier resin is 50 parts by mass or less, the flexibility of the pressure-sensitive adhesive composition of this embodiment is further improved, and the pressure-sensitive adhesive composition can exhibit superior adhesion to the adherend. A more preferred lower limit of the content of the tackifier resin is 15 parts by mass, and a more preferred upper limit is 40 parts by mass.

[0078] The pressure-sensitive adhesive composition of the present embodiment preferably contains a crosslinking agent from the viewpoint of being able to appropriately adjust the degree of crosslinking. From the viewpoint of storage stability, etc., the crosslinking agent may be blended into the pressure-sensitive adhesive composition of the present embodiment immediately before forming the pressure-sensitive adhesive layer. Examples of the crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, and a metal chelate-based crosslinking agent. Among these, the crosslinking agent preferably contains at least one selected from the group consisting of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent, and more preferably is an isocyanate-based crosslinking agent, so that the pressure-sensitive adhesive composition of the present embodiment can exhibit superior adhesion to the adherend.

[0079] In the pressure-sensitive adhesive composition of this embodiment, the preferred lower limit of the content of the crosslinking agent relative to 100 parts by mass of the total of the (meth)acrylic monomer and the (meth)acrylic polymer is 0.01 parts by mass, and the preferred upper limit is 10 parts by mass. By having the content of the crosslinking agent within this range, the degree of crosslinking of the pressure-sensitive adhesive composition of this embodiment can be appropriately adjusted, allowing for superior adhesive strength and superior adhesion to the adherend. The more preferred lower limit of the content of the crosslinking agent is 0.1 parts by mass, the more preferred upper limit is 8.0 parts by mass, the even more preferred lower limit is 1.0 part by mass, and the even more preferred upper limit is 5.0 parts by mass. In this specification, the "content of crosslinking agent" refers to the content of the solids of the crosslinking agent.

[0080] The pressure-sensitive adhesive composition of the present embodiment may further contain a crosslinking catalyst for accelerating crosslinking by the crosslinking agent. Examples of the crosslinking catalyst include crosslinking catalysts for the isocyanate-based crosslinking agents, such as dibutyltin dilaurate, dibutyltin diacetate, and dioctyltin dilaurate.

[0081] The pressure-sensitive adhesive composition of the present embodiment preferably further contains a pigment. By containing a pigment, the pressure-sensitive adhesive composition of the present embodiment can exhibit light-blocking properties, making it more suitable for use in fixing electronic device components or vehicle-mounted components.

[0082] Examples of the pigment include color pigments such as black fillers, etc. Specific examples of the black fillers include carbon black and titanium black.

[0083] The average particle size of the black filler preferably has a lower limit of 0.01 μm and an upper limit of 1.0 μm. When the average particle size of the black filler is within the above range, the pressure-sensitive adhesive composition of the present embodiment can better exhibit light-blocking properties. A more preferred lower limit of the average particle size of the black filler is 0.1 μm and a more preferred upper limit is 0.8 μm. The average particle size can be determined, for example, by observing 50 arbitrary black fillers with an electron microscope or an optical microscope and calculating the average particle size of each black filler, or by performing laser diffraction particle size distribution measurement.

[0084] In the pressure-sensitive adhesive composition of this embodiment, the preferred lower limit of the pigment content relative to 100 parts by mass of the total of the (meth)acrylic monomer and the (meth)acrylic polymer is 0.1 parts by mass, and the preferred upper limit is 5.0 parts by mass. When the pigment content is within this range, the pressure-sensitive adhesive composition of this embodiment can exhibit better light-blocking properties. The more preferred lower limit of the pigment content is 0.5 parts by mass, and the more preferred upper limit is 3.0 parts by mass.

[0085] The pressure-sensitive adhesive composition of the present embodiment may contain additives such as a silane coupling agent, a plasticizer, a softener, a filler, a dye, etc., as needed, within the scope of not impairing the object of the present invention.

[0086] The method for producing the pressure-sensitive adhesive composition of the present embodiment is not particularly limited, and the composition can be produced by a conventionally known production method, for example, by adding the above-mentioned (meth)acrylic monomer and the above-mentioned (meth)acrylic polymer, and, if necessary, a polymerization initiator, a tackifier resin, a crosslinking agent, a solvent, etc.

[0087] The preferred lower limit of the bio-derived carbon content in the PSA composition of this embodiment is 10%. By having the bio-derived carbon content in the PSA composition of this embodiment be 10% or more, the PSA composition of this embodiment is excellent in terms of saving petroleum resources and reducing carbon dioxide emissions, and can reduce the environmental impact. A more preferred lower limit of the bio-derived carbon content in the PSA composition of this embodiment is 40%, and an even more preferred lower limit is 60%. The upper limit of the bio-derived carbon content in the PSA composition of this embodiment is not particularly limited and may be 100%. While bio-derived carbon contains a certain proportion of the radioactive isotope (C-14), petroleum-derived carbon contains almost no C-14. Therefore, the "biological carbon content" in this specification can be calculated by measuring the concentration of C-14 contained in the PSA composition or PSA layer. Specifically, it can be measured in accordance with ASTM D6866-22, a standard widely used in the bioplastics industry.

[0088] The content of biologically-derived carbon in the pressure-sensitive adhesive composition of this embodiment can be adjusted by changing each component constituting the pressure-sensitive adhesive composition of this embodiment to a biologically-derived material and by changing the content of the biologically-derived material.

[0089] The present embodiment also includes a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a cured product of the pressure-sensitive adhesive composition of the present embodiment. The gel fraction and the content of bio-derived carbon in the pressure-sensitive adhesive layer, which will be described later, can be adjusted to the values ​​described later by adjusting the types and contents of the components constituting the pressure-sensitive adhesive composition of the present embodiment.

[0090] The pressure-sensitive adhesive composition may be cured by light irradiation or by heating, but from the viewpoint of energy consumption, curing by light irradiation is preferred. Furthermore, in curing the pressure-sensitive adhesive composition, light irradiation and heating may be used in combination. In curing the pressure-sensitive adhesive composition, heating can be performed to reduce the solvent content of the resulting pressure-sensitive adhesive layer. A method for obtaining a cured product of the pressure-sensitive adhesive composition includes, for example, using a light source at a wavelength of 365 nm and an illuminance of 35 mW / cm. ２ or by polymerizing the (meth)acrylic monomer, the (meth)acrylic polymer, etc. in the pressure-sensitive adhesive composition to obtain a (meth)acrylic copolymer by irradiating the pressure-sensitive adhesive composition with ultraviolet light of 1000 nm or by heating for 60 seconds in an environment of 130° C. In this specification, the term "(meth)acrylic copolymer" refers to a cured product obtained by curing the pressure-sensitive adhesive composition, or a copolymer having a structural unit derived from (meth)acrylate contained in the pressure-sensitive adhesive layer.

[0091] This embodiment also includes a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a (meth)acrylic copolymer having structural units derived from an alkyl (meth)acrylate having a branched alkyl group, wherein the structural units derived from the alkyl (meth)acrylate having a branched alkyl group contain structural units derived from a branched alkyl group-containing alkyl (meth)acrylate that, when converted into a homopolymer, has a glass transition temperature of −55° C. or higher and −15° C. Examples of the (meth)acrylic copolymer having structural units derived from an alkyl (meth)acrylate having a branched alkyl group include the (meth)acrylic polymer in the pressure-sensitive adhesive composition, a copolymer obtained by copolymerizing the (meth)acrylic polymer with the (meth)acrylic monomer, and a copolymer obtained by copolymerizing the (meth)acrylic monomer.

[0092] In the (meth)acrylic copolymer, examples of the structural unit derived from a branched alkyl group-containing alkyl (meth)acrylate having a glass transition temperature of −55° C. or higher and −15° C. or lower when made into the homopolymer include a structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A) in the (meth)acrylic polymer in the pressure-sensitive adhesive composition. Among these, from the viewpoints of the shear adhesive strength of the pressure-sensitive adhesive layer and adhesion to an adherend, the structural unit derived from a branched alkyl group-containing alkyl (meth)acrylate having a glass transition temperature of −55° C. or higher and −15° C. or lower when made into the homopolymer preferably contains a structural unit derived from the branched alkyl group-containing alkyl (meth)acrylate (A), and more preferably contains a structural end derived from 1-methylheptyl (meth)acrylate.

[0093] In the (meth)acrylic copolymer, the preferred lower limit of the content of the structural units derived from 1-methylheptyl (meth)acrylate is 60% by mass. When the content of the structural units derived from 1-methylheptyl (meth)acrylate is 60% by mass or more, the pressure-sensitive adhesive composition of the present invention can exhibit higher shear adhesive strength and better adhesion to adherends. The more preferred lower limit of the content of the structural units derived from 1-methylheptyl (meth)acrylate is 70% by mass, and even more preferred lower limit is 80% by mass. Furthermore, the preferred upper limit of the content of the structural units derived from 1-methylheptyl (meth)acrylate is 99% by mass. When the content of the structural units derived from 1-methylheptyl (meth)acrylate is 99% by mass or less, the pressure-sensitive adhesive composition of the present invention can exhibit better adhesive strength. The more preferred upper limit of the content of the structural units derived from 1-methylheptyl (meth)acrylate is 97% by mass, and even more preferred upper limit is 95% by mass. The content of the structural unit derived from 1-methylheptyl (meth)acrylate in the (meth)acrylic copolymer can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy of the (meth)acrylic copolymer ( １ H-NMR, １３The amount of hydrogen can be calculated from the integrated intensity ratio of the peak of hydrogen derived from the 1-methylheptyl (meth)acrylate by performing spectroscopy (e.g., C-NMR) and the like.

[0094] Preferably, the pressure-sensitive adhesive layer does not contain an organic solvent, or contains an organic solvent, but the content of the organic solvent in the pressure-sensitive adhesive layer is 5,000 ppm or less. By not containing an organic solvent in the pressure-sensitive adhesive layer, or by containing an organic solvent in the pressure-sensitive adhesive layer and the content of the organic solvent in the pressure-sensitive adhesive layer is 5,000 ppm or less, the environmental impact of the pressure-sensitive adhesive tape of this embodiment due to volatile organic compounds (VOCs) can be reduced. If the pressure-sensitive adhesive layer contains an organic solvent, the upper limit of the organic solvent content is more preferably 30,000 ppm, even more preferably 1,000 ppm, and even more preferably 500 ppm. It is most preferred that the pressure-sensitive adhesive layer does not contain an organic solvent. The organic solvent content can be measured by gas chromatography-mass spectrometry (GC-MS). Specifically, the organic solvent contained in the PSA layer is identified, and then the sol component of the PSA layer is diluted with chloroform using the organic solvent as a standard sample with a known content, followed by gas chromatography-mass spectrometry (GC-MS) of the measurement sample. A calibration curve is created using the measured peak areas, and the organic solvent content is calculated using the created calibration curve. The "sol component" refers to the component of the PSA layer excluding the gel component. The sol component of the PSA layer can be obtained, for example, by immersing the PSA layer in tetrahydrofuran at 23°C for 24 hours, filtering the insoluble portion through a 200-mesh wire mesh, and removing the gel component. The gas chromatography-mass spectrometry measurement conditions are, for example, as follows: <GC-MS measurement conditions> Gas chromatograph mass spectrometer: JMS Q1500 (manufactured by JEOL Ltd.) Mobile phase: Helium Helium flow rate: 1.0 mL / min Detector: Quadrupole mass spectrometer Ionization method: EI method Column: SLB-5ms capillary GC column (manufactured by Sigma-Aldrich) Injection port temperature: 320°C Column temperature: 40°C to 340°C Injection volume: 1.0 μL

[0095] Examples of methods for adjusting the solvent content in the pressure-sensitive adhesive layer include a method of reducing the solvent content in the pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive layer, a method of reducing the amount of solvent used in synthesizing the (meth)acrylic copolymer when forming the pressure-sensitive adhesive layer, and a method of curing the pressure-sensitive adhesive composition by ultraviolet irradiation, electron beam irradiation, or the like to form a pressure-sensitive adhesive layer, followed by drying.

[0096] The preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 10% by mass, and the preferred upper limit is 70% by mass. When the gel fraction of the pressure-sensitive adhesive layer is 10% by mass or more, the cohesive strength of the pressure-sensitive adhesive layer is further improved, and the pressure-sensitive adhesive tape of this embodiment exhibits higher shear adhesive strength. When the gel fraction of the pressure-sensitive adhesive layer is 70% by mass or less, the pressure-sensitive adhesive tape of this embodiment has further improved adhesion to an adherend. The more preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 20% by mass, and the more preferred upper limit is 60% by mass, and even more preferred lower limit is 30% by mass, and even more preferred upper limit is 55% by mass. The gel fraction of the pressure-sensitive adhesive layer is measured by the following method, etc. That is, first, the pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer is cut into a flat rectangular shape with a width of 20 mm and a length of 40 mm to prepare a test piece, and the test piece is immersed in tetrahydrofuran at 23°C for 24 hours, then removed from the tetrahydrofuran, and dried at 110°C for 1 hour. The mass of the test piece after drying is measured, and the gel fraction is calculated using the following formula (1). Note that no release film for protecting the pressure-sensitive adhesive layer is laminated on the test piece. When the pressure-sensitive adhesive tape of the present invention is a non-support type tape that does not have a substrate layer, the measurement is carried out using a test piece obtained by attaching it to a substrate and cutting it, or the gel fraction is calculated by the W in the following formula (1) without using a substrate layer. ０ The calculation is performed assuming that the gel fraction is 0. Gel fraction (mass%) = 100 × (W ２ -W ０ ) / (W １ -W ０ ) (1) (W ０ : Mass of the base material layer, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0097] Methods for adjusting the gel fraction of the pressure-sensitive adhesive layer to fall within the above-mentioned range include, for example, a method for adjusting the type and content of each component constituting the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer as described above (for example, a method for changing the type and content of the crosslinking agent), and a method for adjusting the illuminance or irradiation time of the electron beam or ultraviolet light used when irradiating with an electron beam or ultraviolet light to form the pressure-sensitive adhesive layer, but are not limited to these methods.

[0098] The preferred lower limit of the bio-derived carbon content in the pressure-sensitive adhesive layer is 10%. When the bio-derived carbon content in the pressure-sensitive adhesive layer is 10% or more, the pressure-sensitive adhesive tape of the present embodiment is excellent in terms of saving petroleum resources and reducing carbon dioxide emissions, and is able to reduce the environmental burden. A more preferred lower limit of the bio-derived carbon content in the pressure-sensitive adhesive layer is 40%, and an even more preferred lower limit is 60%. Furthermore, the upper limit of the bio-derived carbon content in the pressure-sensitive adhesive layer is not particularly limited, and may be 100%.

[0099] The glass transition temperature of the pressure-sensitive adhesive layer measured by dynamic viscoelasticity measurement at a measurement frequency of 10 Hz (hereinafter sometimes simply referred to as the "glass transition temperature of the pressure-sensitive adhesive layer") preferably has a lower limit of -20°C and an upper limit of 35°C. When the glass transition temperature of the pressure-sensitive adhesive layer is within the above range, the pressure-sensitive adhesive tape of this embodiment can exhibit higher shear adhesive strength and better adhesion to the adherend. A more preferred lower limit of the glass transition temperature of the pressure-sensitive adhesive layer is -10°C, and a more preferred upper limit is 25°C. In this specification, the "glass transition temperature of the pressure-sensitive adhesive layer" refers to the temperature at which the maximum due to micro-Brownian motion appears among the maximums of the loss tangent (tan δ) obtained by dynamic viscoelasticity measurement. The following method, for example, can be used to measure the glass transition temperature of the pressure-sensitive adhesive layer. That is, first, the pressure-sensitive adhesive layers are stacked to prepare a laminate having a thickness of approximately 1 mm, and this is cut into a width of 6 mm and a length of 10 mm to obtain a test piece. Next, the obtained test piece is subjected to dynamic viscoelasticity measurement in a shear mode using a dynamic viscoelasticity measuring device under the conditions of a measurement temperature of −150° C. to 200° C., a temperature rise rate of 5° C. / min, a measurement frequency of 10 Hz, and a strain of 0.08% in a nitrogen atmosphere. Examples of the dynamic viscoelasticity measuring device include DVA-200 (manufactured by IT Measurement & Control Co., Ltd.).

[0100] The preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 3 μm, and the preferred upper limit is 300 μm. When the thickness of the pressure-sensitive adhesive layer is 3 μm or more, the pressure-sensitive adhesive tape of this embodiment has sufficient adhesive strength. When the thickness of the pressure-sensitive adhesive layer is 300 μm or less, the pressure-sensitive adhesive tape of this embodiment is easily removable. The more preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 5 μm, and the more preferred upper limit is 200 μm, and the even more preferred lower limit is 10 μm, and the even more preferred upper limit is 100 μm.

[0101] The pressure-sensitive adhesive tape of the present embodiment may be a non-support type tape that does not have a base layer, or may be a support type tape that has a base layer. In particular, it is preferable that the pressure-sensitive adhesive tape of the present invention has a base layer. Since the pressure-sensitive adhesive layer also has excellent adhesion to the base layer, the pressure-sensitive adhesive tape of the present invention can exhibit sufficient adhesive strength immediately after lamination by having a base layer. When the pressure-sensitive adhesive tape of the present embodiment is a support type tape that has a base layer, it may be a single-sided pressure-sensitive adhesive tape that has a pressure-sensitive adhesive layer on one side of the base layer, or a double-sided pressure-sensitive adhesive tape that has the pressure-sensitive adhesive layers on both sides of the base layer.

[0102] Examples of substrates used for the substrate layer include films, nonwoven fabrics, and foam substrates. The substrate used for the substrate layer is preferably a substrate made of a biologically-derived material, from the viewpoint of increasing the content of biologically-derived carbon in the entire pressure-sensitive adhesive tape. Examples of biologically-derived materials include polyesters (PES) such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS), polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetyl cellulose (TAC), cellulose, and polyamide (PA), which are derived from plants.

[0103] Furthermore, from the perspective of reducing the use of new petroleum resources and reducing the environmental burden by suppressing carbon dioxide emissions, substrates made from recycled resources may be used. Examples of resource recycling methods include collecting waste materials such as packaging containers, home appliances, automobiles, construction materials, and food, as well as waste generated during manufacturing processes, and then cleaning, decontaminating, or decomposing the extracted materials by heating or fermentation to reuse them as raw materials. Examples of substrates made from recycled resources include films and nonwoven fabrics made from PET, PBT, PE, PP, PA, etc., which are made from recycled plastics that have been re-resinized. Furthermore, the collected waste materials may be burned and used as thermal energy for the production of substrates and their raw materials. The oils and fats contained in the collected waste materials may be mixed with petroleum, fractionated, and purified, and then used as raw materials.

[0104] From the viewpoint of further improving conformability to irregularities, the substrate used in the substrate layer preferably includes a foam substrate. The foam substrate is preferably a foam substrate containing at least one selected from the group consisting of PE, PP, and PU, and from the viewpoint of achieving a high degree of both flexibility and strength, a foam substrate containing PE is more preferred. Examples of the constituents of the foam substrate containing PE include PE made from sugarcane.

[0105] A preferred method for producing the foam base material is, for example, to prepare a foamable resin composition containing a PE resin containing sugarcane-derived PE and a foaming agent, and then foam the foaming agent when extruding the foamable resin composition into a sheet using an extruder, and optionally crosslink the resulting polyolefin foam.

[0106] The preferred lower limit of the thickness of the foam substrate is 50 μm, and the preferred upper limit is 5000 μm. By having the thickness of the foam substrate within this range, it is possible to exhibit high impact resistance while exhibiting high flexibility that allows it to be adhered to the shape of the adherend. The more preferred upper limit of the thickness of the foam substrate is 1000 μm, even more preferred upper limit is 300 μm, and even more preferred upper limit is 100 μm.

[0107] The substrate used in the substrate layer is preferably a film containing PES or a film containing PA from the viewpoint of substrate strength. Furthermore, a film containing PA is preferred from the viewpoint of heat resistance and oil resistance. Examples of PA include nylon 11, nylon 1010, nylon 610, nylon 510, and nylon 410, which are made from castor oil, and nylon 56, which is made from cellulose.

[0108] The preferred lower limit of the thickness of the substrate is 1 μm, and the preferred upper limit is 5000 μm. By having the thickness of the substrate within this range, it is possible to obtain an adhesive tape that has stiffness while exhibiting high flexibility so that it can be adhered to the shape of the adherend. The more preferred lower limit of the thickness of the substrate is 4 μm, and the more preferred upper limit is 1000 μm, and even more preferred lower limit is 10 μm, and even more preferred upper limit is 300 μm.

[0109] The pressure-sensitive adhesive tape of this embodiment has a total thickness (for example, the thickness of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive tape has only a pressure-sensitive adhesive layer; or the sum of the thickness of the pressure-sensitive adhesive layer and the thickness of the base layer when the pressure-sensitive adhesive tape has a pressure-sensitive adhesive layer and a base layer) of preferably 3 μm at the lower limit and 6000 μm at the upper limit. Having a total thickness within this range of the pressure-sensitive adhesive tape of this embodiment further increases the adhesive strength of the pressure-sensitive adhesive tape of this embodiment. A more preferred lower limit of the total thickness of the pressure-sensitive adhesive tape of this embodiment is 5 μm, a more preferred upper limit is 1200 μm, an even more preferred lower limit is 10 μm, an even more preferred upper limit is 500 μm, and an even more preferred upper limit is 100 μm. It should be noted that, in this specification, the "total thickness of the pressure-sensitive adhesive tape" does not include the thickness of a separator such as a release PET film that protects the outermost pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape.

[0110] The method for producing the pressure-sensitive adhesive tape of this embodiment is not particularly limited, and the tape can be produced by a conventionally known production method. For example, in the case of a double-sided pressure-sensitive adhesive tape, the following method can be used. First, a pressure-sensitive adhesive composition A is prepared by the method described above. The obtained pressure-sensitive adhesive composition A is applied to the surface of a release film, and then another prepared release film is placed on top of it with its release-treated surface facing the coated pressure-sensitive adhesive composition A to seal the pressure-sensitive adhesive composition A. UV light is irradiated onto the pressure-sensitive adhesive composition A from the release film side to form a pressure-sensitive adhesive layer A containing a cured product of the pressure-sensitive adhesive composition A. The obtained pressure-sensitive adhesive layer A is placed on a substrate and pressed with a rubber roller or the like to produce a laminate. Next, a pressure-sensitive adhesive layer B is formed in the same manner as for the pressure-sensitive adhesive layer A. Then, the pressure-sensitive adhesive layer B is placed on the back surface of the substrate on which the pressure-sensitive adhesive layer A has been formed to produce a laminate. The laminate is then pressed with a rubber roller or the like to produce a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both sides of the substrate, the surfaces of the pressure-sensitive adhesive layers being covered with release films.

[0111] Alternatively, two sets of laminate films may be prepared in a similar manner, and these laminate films may be superimposed on each of both surfaces of a substrate with the pressure-sensitive adhesive layer of the laminate film facing the substrate to prepare a laminate. This laminate may then be pressed with a rubber roller or the like to obtain a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both surfaces of the substrate and in which the surfaces of the pressure-sensitive adhesive layers are covered with release films.

[0112] The use of the pressure-sensitive adhesive tape of this embodiment is not particularly limited, but it is preferably used for fixing electronic device components or vehicle-mounted components. Specifically, the pressure-sensitive adhesive tape of this embodiment can be suitably used for adhesively fixing electronic device components in large portable electronic devices, adhesively fixing vehicle-mounted components (e.g., vehicle-mounted panels), etc.

[0113] A method for producing a pressure-sensitive adhesive tape, which includes a step of curing the pressure-sensitive adhesive composition of the present embodiment by irradiating it with light, also constitutes one aspect of the present invention.

[0114] Examples of the step of curing by irradiating light include a step of applying the pressure-sensitive adhesive composition or a solution of the pressure-sensitive adhesive composition and a photopolymerization initiator to the release-treated surface of a substrate or a release film, sealing the pressure-sensitive adhesive composition, and irradiating the composition with light. The light irradiation conditions in the step include, for example, a wavelength of 365 nm and an irradiation intensity of 35 mW / cm. ２ The irradiation dose of light is 1000 mJ / cm ２ Examples of such a method include irradiating the light so that the

[0115] According to the present invention, it is possible to provide a pressure-sensitive adhesive composition that exhibits high shear adhesive strength and excellent adhesion to adherends, and that can reduce the environmental load. Also, according to the present invention, it is possible to provide a pressure-sensitive adhesive tape that has high shear adhesive strength and excellent adhesion to adherends. Furthermore, according to the present invention, it is possible to provide a method for producing a pressure-sensitive adhesive tape that uses the pressure-sensitive adhesive composition.

[0116] 1A and 1B are diagrams showing a shear adhesive strength test and a high temperature retention test, respectively.

[0117] The following examples further illustrate aspects of the present invention, but the present invention is not limited to these examples. The materials used in the examples and comparative examples are as follows.

[0118] <1-Methylheptyl acrylate containing bio-derived carbon> Ricinoleic acid derived from castor oil was alkali-fused to obtain a mixture containing sebacic acid and 1-methylheptyl alcohol. Next, sebacic acid was separated from the obtained mixture by distillation to obtain 1-methylheptyl alcohol containing bio-derived carbon. 1-Methylheptyl acrylate containing bio-derived carbon was prepared by esterifying the obtained 1-methylheptyl alcohol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.).

[0119] <n-Hexyl acrylate containing bio-derived carbon> Linoleic acid derived from castor oil was converted to linoleic acid hydroperoxide using lipoxygenase, and then a mixture containing n-hexylaldehyde was obtained using isomerase. The resulting mixture was distilled to obtain n-hexylaldehyde containing bio-derived carbon. The obtained n-hexylaldehyde containing bio-derived carbon was then hydrogenated to obtain n-hexyl alcohol containing bio-derived carbon. The obtained n-hexyl alcohol containing bio-derived carbon was esterified with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare n-hexyl acrylate containing bio-derived carbon.

[0120] <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. Next, undecylenic acid was separated from the obtained mixture by distillation to obtain n-heptyl alcohol containing bio-derived carbon. The obtained n-heptyl alcohol containing bio-derived carbon was esterified with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare n-heptyl acrylate containing bio-derived carbon.

[0121] <Isobornyl acrylate containing bio-derived carbon> Camphene containing bio-derived carbon was obtained by isomerizing pinene extracted from pine resin. Camphene containing bio-derived carbon was reacted with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare isobornyl acrylate containing bio-derived carbon.

[0122] <2-hydroxyethyl acrylate containing bio-derived carbon> Ethanol containing bio-derived carbon was obtained by fermenting sugar contained in sugarcane. The obtained ethanol containing bio-derived carbon was dehydrated to obtain ethylene, which was then oxidized to obtain ethylene oxide, to which water was added to obtain ethylene glycol containing bio-derived carbon. The obtained ethylene glycol containing bio-derived carbon was esterified with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare 2-hydroxyethyl acrylate containing bio-derived carbon.

[0123] <Tetrahydrofurfuryl acrylate containing bio-derived carbon> Tetrahydrofurfuryl alcohol containing bio-derived carbon was obtained by hydrogenating furfural contained in sugarcane. Tetrahydrofurfuryl alcohol containing bio-derived carbon was reacted with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare tetrahydrofurfuryl acrylate containing bio-derived carbon.

[0124] <Bio-derived carbon-free monomers> ・Isobutyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・Isoamyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・Isodecyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・Isostearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) ・Methyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・Ethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・n-Butyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・n-Octyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・2-Ethylhexyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) ・Cyclohexyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・Acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) ・Dimethylacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.) ・2-Methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) ・1,6-Hexanediacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) Urethane diacrylate (polyether-based multifunctional urethane acrylate: "UA-160TM" manufactured by Shin-Nakamura Chemical Co., Ltd.) Bismaleimide compound (2,2-bis[4-(4-maleimidophenoxy)phenyl]propane (manufactured by Tokyo Chemical Industry Co., Ltd.))

[0125] <Photopolymerization initiator> Photopolymerization initiator A: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (manufactured by IGM Resins, "Omnirad TPO", number of photopolymerization reaction sites: 1) Photopolymerization initiator B: Omnipol TP (manufactured by IGM Resins, number of photopolymerization reaction sites: 3)

[0126] <Tackifying Resin> Tackifying Resin A: Terpene-based tackifying resin (terpene phenol-based resin) (manufactured by Yasuhara Chemical Co., Ltd., "YS Polystar G150", softening temperature: 145°C to 155°C)

[0127] <Crosslinking agent> Isocyanate-based crosslinking agent (manufactured by Covestro, "Desmodur L-75", diluted with ethyl acetate (dilution concentration 75%)) Epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., "Tetrad X")

[0128] <Pigment> Carbon black (Toyo Color Co., Ltd., "Multilac A903 Black")

[0129] Example 1 (1) Production of (meth)acrylic polymer: 100 parts by mass of ethyl acetate was added as a polymerization solvent to a reaction vessel, and after bubbling with nitrogen, the reaction vessel was heated while flowing in nitrogen to initiate reflux. Subsequently, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile as a polymerization initiator 10 times with ethyl acetate was added to the reaction vessel, and 47.45 parts by mass of 1-methylheptyl acrylate containing bio-derived carbon, 0.05 parts by mass of 2-hydroxyethyl acrylate containing bio-derived carbon, and 2.5 parts by mass of acrylic acid were added dropwise over a period of 2 hours. After completion of the dropwise addition, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile as a polymerization initiator 10 times with ethyl acetate was added again to the reaction vessel, and a polymerization reaction was carried out for 4 hours to obtain a (meth)acrylic polymer-containing solution. The obtained (meth)acrylic polymer-containing solution was heated and dried in an oven at 110°C for 1 hour to completely remove the ethyl acetate, thereby obtaining (meth)acrylic polymer A. Regarding the weight average molecular weight of (meth)acrylic polymer A, the obtained (meth)acrylic polymer-containing solution was diluted 50 times with tetrahydrofuran (THF), and the resulting diluted solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare a measurement sample. This measurement sample was supplied to a gel permeation chromatograph (manufactured by Waters Corporation, "2690 Separations Module") and subjected to GPC measurement under conditions of a sample flow rate of 1 mL / min and a column temperature of 40 ° C. The polystyrene-equivalent molecular weight of the (meth)acrylic polymer was measured, and the weight average molecular weight was determined. The results are shown in Table 1.

[0130] (2) Preparation of Pressure-Sensitive Adhesive Composition, Production of Pressure-Sensitive Adhesive Tape A pressure-sensitive adhesive composition was prepared by adding 50.0 parts by mass of the obtained (meth)acrylic polymer A, 47.45 parts by mass of 1-methylheptyl acrylate containing bio-derived carbon, 0.05 parts by mass of 2-hydroxyethyl acrylate containing bio-derived carbon, 2.5 parts by mass of acrylic acid, 0.3 parts by mass of photopolymerization initiator B, and an isocyanate-based crosslinking agent so that the solids content was 1.0 part by mass. The prepared pressure-sensitive adhesive composition was applied to the release-treated surface of a 50 μm-thick release PET film, and then a 38 μm-thick release PET film was placed on top of it so that the release-treated surface faced the coated pressure-sensitive adhesive composition, sealing the pressure-sensitive adhesive composition. A UV-LED irradiation device (manufactured by CCS Inc., "UVS01-01") was used, and the wavelength was 365 nm and the irradiation intensity was 35 mW / cm. ２ The ultraviolet light irradiation dose is 1000 mJ / cm ２ The adhesive composition was irradiated through a release PET film so that the adhesive composition was cured to form an adhesive layer having a thickness of 50 μm, and an adhesive tape was obtained.

[0131] (3) Measurement of the content ratio of organic solvent in the pressure-sensitive adhesive composition The obtained pressure-sensitive adhesive composition was diluted with chloroform to prepare a sample solution. The obtained sample solution was subjected to gas chromatography mass spectrometry (GC-MS) measurement, and the content ratio (mass %) of the organic solvent in the pressure-sensitive adhesive composition was measured from the peak area of ​​the obtained spectrum. The results are shown in Table 3. <GC-MS measurement conditions> Gas chromatograph mass spectrometer: JMS Q1500 (manufactured by JEOL Ltd.) Mobile phase: helium Helium flow rate: 1.0 mL / min Detector: quadrupole mass spectrometer Ionization method: EI method Column: SLB-5ms capillary GC column (manufactured by Sigma-Aldrich) Injection port temperature: 320°C Column temperature: 40°C to 340°C Injection amount: 1.0 μL

[0132] (4) Measurement of gel fraction of adhesive layer The release PET film on one side of the obtained adhesive tape was peeled off, and the tape was attached to a 23 μm thick base PET film (manufactured by Futamura Chemical Co., Ltd., "FE2002"), and cut into a flat rectangular shape with a width of 20 mm and a length of 40 mm. The release PET film on the other side of the adhesive tape was then peeled off to prepare a test piece, and its mass was measured. The test piece was immersed in tetrahydrofuran at 23°C for 24 hours, then removed from the tetrahydrofuran and dried at 110°C for 1 hour. The mass of the dried test piece was measured, and the gel fraction (mass%) was calculated using the following formula (1). The results are shown in Table 3. Gel fraction (mass%) = 100 × (W ２ -W ０ ) / (W １ -W ０ ) (1) (W ０ : Mass of the substrate, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0133] (5) Measurement of Organic Solvent Content in Pressure-Sensitive Adhesive Layer In the above-mentioned "(4) Measurement of Gel Fraction of Pressure-Sensitive Adhesive Layer," the gel component of the pressure-sensitive adhesive that had absorbed and swollen tetrahydrofuran was filtered, and the resulting sol component of the pressure-sensitive adhesive layer was diluted with chloroform to prepare a sample solution. The resulting sample solution was subjected to gas chromatography mass spectrometry (GC-MS), and the content (ppm) of the organic solvent in the pressure-sensitive adhesive layer was measured from the peak area of ​​the obtained spectrum. The results are shown in Table 3. <GC-MS Measurement Conditions> Gas chromatograph mass spectrometer: JMS Q1500 (manufactured by JEOL Ltd.) Mobile phase: helium Helium flow rate: 1.0 mL / min Detector: quadrupole mass spectrometer Ionization method: EI method Column: SLB-5ms capillary GC column (manufactured by Sigma-Aldrich) Injection port temperature: 320°C Column temperature: 40°C to 340°C Injection volume: 1.0 μL

[0134] (Examples 2 to 16, 19 to 21, 24 to 36, Comparative Examples 1 to 2, 5 to 6) Pressure-sensitive adhesive tapes having pressure-sensitive adhesive layers of the same thickness as in Example 1 were obtained in the same manner as in Example 1, except that the types and amounts of each component of the pressure-sensitive adhesive composition were changed as shown in Tables 3 to 6. Furthermore, the weight-average molecular weight of the (meth)acrylic polymer, the content of the solvent in the pressure-sensitive adhesive composition, the gel fraction of the pressure-sensitive adhesive layer, and the content of the solvent in the pressure-sensitive adhesive layer were measured in the same manner as in Example 1. The results are shown in Tables 1 to 6.

[0135] (Examples 17 and 18) Pressure-sensitive adhesive compositions were prepared in the same manner as in Example 1, except that the types and blending amounts of each component of the pressure-sensitive adhesive composition were as shown in Table 4. The obtained pressure-sensitive adhesive composition was coated on the release-treated surface of a 50 μm-thick release PET film, and then a 38 μm-thick release PET film was placed on top of it so that the release-treated surface faced the coated pressure-sensitive adhesive composition to seal the pressure-sensitive adhesive composition. The adhesive composition was then irradiated with UV-LED irradiation equipment (manufactured by CCS Inc., "UVS01-01") at a wavelength of 365 nm and an irradiation intensity of 35 mW / cm. ２ The adhesive composition was irradiated with ultraviolet light through a release PET film to cure the adhesive composition, forming a 50 μm thick adhesive layer. The resulting adhesive layer was then pressed back and forth at a speed of 300 mm / min using a 2 kg rubber roller, and bonded to one side of the substrate shown in Table 4. Furthermore, an adhesive layer having the same composition and thickness was formed on the release-treated surface of another 50 μm thick release PET film by the same method, and bonded to the other side of the substrate. The film was then pressed back and forth at a speed of 300 mm / min using a 2 kg rubber roller, and laminated together to obtain an adhesive tape (support type) having an adhesive layer and a release PET film on both sides of the substrate. The weight-average molecular weight of the (meth)acrylic polymer, the solvent content in the adhesive layer, and the gel fraction of the adhesive layer were measured in the same manner as in Example 1. The gel fraction of the pressure-sensitive adhesive layer was measured using a test piece obtained by cutting the pressure-sensitive adhesive tape into a flat rectangular shape with a width of 20 mm and a length of 40 mm and then peeling off the release PET films on both sides. The results are shown in Tables 1 and 4.

[0136] The substrates used as the substrate layers in Examples 17 and 18 are as follows: PET film (manufactured by Futamura Chemical Co., Ltd., "FE2002", thickness 50 μm) PE foam (manufactured by Sekisui Chemical Co., Ltd., "WL02", thickness 150 μm)

[0137] Examples 22-23, Comparative Example 4 Pressure-sensitive adhesive compositions were prepared and pressure-sensitive adhesive tapes were obtained in the same manner as in Example 1, except that the types and amounts of each component of the pressure-sensitive adhesive composition were as shown in Tables 4 and 6, and that after the pressure-sensitive adhesive composition was cured to obtain a pressure-sensitive adhesive layer, the release film on one side was peeled off and the composition was cured at 110°C for 5 minutes. Furthermore, the weight-average molecular weight of the (meth)acrylic polymer, the solvent content in the pressure-sensitive adhesive composition, the gel fraction of the pressure-sensitive adhesive layer, and the solvent content in the pressure-sensitive adhesive layer were measured in the same manner as in Example 1. The results are shown in Tables 1, 4, and 6. The "solvent" in "Composition of Pressure-sensitive Adhesive Composition" for Examples 22-23 and Comparative Examples 3-4 in Tables 4 and 6 was added when preparing the pressure-sensitive adhesive composition in "(2) Preparation of Pressure-sensitive Adhesive Composition, Production of Pressure-sensitive Adhesive Tape" described above, and is different from the solvent derived from the (meth)acrylic polymer-containing solution described above.

[0138] (Comparative Example 3) A pressure-sensitive adhesive composition was obtained by adding 100 parts by weight of (meth)acrylic polymer N, 30.0 parts by weight of tackifier resin A, 0.5 parts by weight of an isocyanate-based crosslinking agent, and 200.0 parts by weight of ethyl acetate as a solvent. After thoroughly stirring the resulting pressure-sensitive adhesive composition solution, it was coated with a doctor knife onto the release-treated surface of a 50 μm-thick release polyethylene terephthalate (PET) film with one side treated for release, and heated at 110 ° C for 10 minutes to dry the coating solution, thereby forming a 50 μm-thick pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. Furthermore, a 25 μm-thick release PET film with one side treated for release was prepared, and the formed pressure-sensitive adhesive layer and the release-treated surface were overlapped, and then aged in an environment of 40 ° C for 48 hours to obtain a pressure-sensitive adhesive tape. Furthermore, the weight average molecular weight of the (meth)acrylic polymer, the content of the solvent in the pressure-sensitive adhesive composition, the gel fraction of the pressure-sensitive adhesive layer, and the content of the solvent in the pressure-sensitive adhesive layer were measured in the same manner as in Example 1. The results are shown in Tables 1 and 6.

[0139] <Evaluation> The pressure-sensitive adhesive tapes obtained in the Examples and Comparative Examples were evaluated by the following methods. The results are shown in Tables 3 to 6.

[0140] (Shear Adhesion Strength) A shear adhesive strength test was conducted to measure the shear adhesive strength of an adhesive tape in accordance with JIS K6850. Figure 1 shows a schematic diagram of the shear adhesive strength test. Specifically, an adhesive tape 1 was first cut into a size of 25 mm x 25 mm, and two SUS (stainless steel) 304 plates 2 (SUS 304 plates washed with ethanol and then wiped dry) measuring 125 mm x 50 mm and 2 mm thick were laminated together as shown in Figure 1. This laminate was then pressed with a 5 kg weight for 10 seconds to bond the plates together, and then allowed to stand at 23°C and 50% RH for 24 hours to produce a test sample in which the two SUS 304 plates 2 were bonded together via the adhesive tape 1. After fixing one SUS304 plate 2 of the obtained test sample, the upper part of the other SUS304 plate 2 was pulled at a speed of 50 mm / min in a direction perpendicular to the lamination direction of the SUS304 plate 2 (the direction of the arrow in Figure 1) using a tensile tester (Shimadzu Corporation, "Autograph AGS-X Precision Universal Testing Machine") under conditions of 23°C and 50% RH. The stress (MPa) at which the adhesive tape 1 broke was measured, and this value was taken as the shear adhesive strength. The shear adhesive strength of the adhesive tape was evaluated by assigning an "A" if the obtained shear adhesive strength was 1.0 MPa or more, a "B" if it was 0.7 MPa or more and less than 1.0 MPa, and a "C" if it was less than 0.7 MPa.

[0141] (Adhesion to Adherend) (1) Adhesion strength immediately after bonding the adhesive tape: The 180° peel force immediately after bonding the adhesive tape to glass was measured. Specifically, first, one release PET film of the adhesive tape was peeled off, and the tape was backed with a 23 μm thick PET film (manufactured by Futamura Chemical Co., Ltd., "FE2002"), then cut into a width of 25 mm and a length of 75 mm. The other release PET film was peeled off to prepare a test piece. This test piece was placed on a 1 mm thick glass plate (manufactured by Matsunami Glass Industry Co., Ltd., "Large Slide Glass, White Edge Polished No. 2") with the adhesive layer (the side to be measured) facing the glass plate, and then bonded to the test piece by rolling a 2 kg rubber roller back and forth once at a speed of 300 mm / min. The test piece was then aged at 23 ° C. and 50% RH for 20 minutes to prepare a test sample. The obtained test samples were peeled in a 180° direction under conditions of 23°C, 50% RH, and a pulling rate of 300 mm / min, and the 180° peel strength (N / 25 mm) immediately after lamination of the pressure-sensitive adhesive tape was measured. The adhesion of the pressure-sensitive adhesive tape to the adherend was evaluated by assigning an "A" if the obtained 180° peel strength was 12 N / 25 mm or more, "B" if it was 10 N / 25 mm or more but less than 12 N / 25 mm, "C" if it was 9 N / 25 mm or more but less than 10 N / 25 mm, and "D" if it was less than 9 N / 25 mm.

[0142] (2) Development rate of adhesive strength immediately after bonding of the adhesive tape The 180° peel force was measured one day after bonding the adhesive tape to the glass, and the development rate of adhesive strength immediately after bonding of the adhesive tape was calculated using the 180° peel force immediately after bonding the adhesive tape to the glass measured by the method described above in "(1) Adhesive strength immediately after bonding the adhesive tape to the glass" and the 180° peel force one day after bonding the adhesive tape to the glass. Specifically, a test piece was first prepared by the method described above in "(1) Adhesive strength immediately after bonding the adhesive tape," and the test piece was then bonded to a glass plate, and aged at 23°C and 50% RH for one day to prepare a test sample. The obtained test sample was peeled in the 180° direction under conditions of 23°C, 50% RH, and a pulling speed of 300 mm / min, and the 180° peel force (N / 25 mm) one day after bonding the adhesive tape was measured. Using the 180° peel force immediately after the adhesive tape was adhered to the glass, measured by the above-mentioned method of "(1) Adhesive strength immediately after adhering the adhesive tape," and the 180° peel force one day after the adhesive tape was adhered to the glass, the adhesive strength development rate (%) immediately after adhering the adhesive tape was calculated according to the following formula (2): Adhesive strength development rate (%) = {(180° peel force immediately after adhering the adhesive tape) / (180° peel force one day after adhering the adhesive tape)} × 100 (2) The adhesion of the adhesive tape to the adherend was evaluated by assigning an "A" to a case where the obtained adhesive strength development rate was 85% or more, a "B" to a case where it was 70% or more but less than 85%, and a "C" to a case where it was less than 70%.

[0143] (High-Temperature Retention Performance) A high-temperature retention test was conducted in accordance with JIS Z 0237:2009. FIG. 2 shows a schematic diagram of the high-temperature retention test. Specifically, first, one side (the side not being measured) of the pressure-sensitive adhesive tape 1 was lined with a 23 μm-thick polyethylene terephthalate film 3 (manufactured by Futamura Chemical Co., Ltd., "FE2002"), and then cut into a width of 25 mm and a length of 75 mm to prepare a test piece. This test piece was placed so that its adhesive layer (the side being measured) faced a 2 mm-thick, 50 mm-wide, and 80 mm-long SUS304 plate 2 (a SUS304 plate washed with ethanol and then wiped dry), and then a 2 kg rubber roller was reciprocated on the test piece at a speed of 300 mm / min, so that a portion of the test piece protruded from the SUS304 plate 3 (adhesion area: width 25 mm, length 25 mm). The test sample was then aged at 23°C and 50% RH for 20 minutes to prepare a test sample. The test sample was placed in an environment of 80°C and 50% RH and allowed to stand for 15 minutes. Under this environment, a 1 kg weight 4 was attached to the polyethylene terephthalate film 3 of the test sample so that a load in the shear direction was applied in accordance with JIS Z 0237:2009. One hour after attaching the weight 4, the amount of shear direction displacement of the adhesive layer from the position where the SUS304 plate 2 was attached was measured. The high-temperature retention performance of the adhesive tape was evaluated by assigning an "A" rating to a case where the displacement was 0.5 mm or less, a "B" rating to a case where the displacement was greater than 0.5 mm but the test piece did not fall, and a "C" rating to a case where the test piece fell. Even if the evaluation was "C," the adhesive tape of this embodiment can still be used without any problems depending on the application.

[0144] (Environmental Load Reduction Ability) Using the content of the organic solvent in the PSA composition measured in "(2) Measurement of the content of the organic solvent in the PSA composition" above, the environmental load reduction ability was evaluated according to the following criteria: A: The PSA composition did not contain an organic solvent, or the content of the organic solvent in the PSA composition was 10 mass% or less. B: The content of the organic solvent in the PSA composition was greater than 10 mass%.

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151] According to the present invention, it is possible to provide a pressure-sensitive adhesive composition that exhibits high shear adhesive strength and excellent adhesion to adherends, and that can reduce the environmental load. Also, according to the present invention, it is possible to provide a pressure-sensitive adhesive tape that has high shear adhesive strength and excellent adhesion to adherends. Furthermore, according to the present invention, it is possible to provide a method for producing a pressure-sensitive adhesive tape that uses the pressure-sensitive adhesive composition.

[0152] 1. Adhesive tape 2. SUS304 plate 3. Polyethylene terephthalate (PET) film 4. Weight (1 kg)

Claims

1. A pressure-sensitive adhesive composition comprising a (meth)acrylic monomer and a (meth)acrylic polymer, wherein the (meth)acrylic monomer comprises an alkyl (meth)acrylate having a branched alkyl group, the alkyl (meth)acrylate having a branched alkyl group comprises a branched alkyl group-containing alkyl (meth)acrylate having a glass transition temperature of -55°C or higher and -15°C or lower when made into a homopolymer, the (meth)acrylic polymer has structural units derived from the alkyl (meth)acrylate, and the pressure-sensitive adhesive composition contains an organic solvent, and the content of the organic solvent in the pressure-sensitive adhesive composition is 10 mass% or less, or the pressure-sensitive adhesive composition does not contain an organic solvent.

2. The pressure-sensitive adhesive composition according to claim 1, wherein the branched alkyl group-containing alkyl(meth)acrylate, which when made into a homopolymer has a glass transition temperature of -55°C or higher and -15°C or lower, includes 1-methylheptyl(meth)acrylate.

3. The pressure-sensitive adhesive composition according to claim 2, wherein the branched alkyl group-containing alkyl(meth)acrylate, which when made into a homopolymer has a glass transition temperature of -55°C or higher and -15°C or lower, comprises an alkyl(meth)acrylate synthesized from an alcohol having an alkyl group, which is a biological material, and (meth)acrylic acid.

4. The pressure-sensitive adhesive composition according to claim 3, wherein the 1-methylheptyl (meth)acrylate comprises 1-methylheptyl (meth)acrylate synthesized from 1-methylheptyl alcohol, which is a biological material, and (meth)acrylic acid.

5. The pressure-sensitive adhesive composition according to claim 1, 2, 3 or 4, wherein the (meth)acrylic monomer comprises a monomer having two or more (meth)acryloyl groups in one molecule.

6. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4 or 5, wherein the (meth)acrylic monomer comprises a monomer having a crosslinkable functional group.

7. The pressure-sensitive adhesive composition according to claim 6, wherein the monomer having a crosslinkable functional group includes a hydroxyl group-containing monomer.

8. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the structural unit derived from the alkyl (meth)acrylate in the (meth)acrylic polymer has a structural unit derived from an alkyl (meth)acrylate having a branched alkyl group, and the structural unit derived from the alkyl (meth)acrylate having a branched alkyl group includes a structural unit derived from an alkyl (meth)acrylate containing a branched alkyl group, which has a glass transition temperature of -55°C or higher and -15°C or lower when made into a homopolymer.

9. The pressure-sensitive adhesive composition according to claim 8, wherein the structural units derived from a branched alkyl group-containing alkyl (meth)acrylate, which when converted into a homopolymer has a glass transition temperature of -55°C or higher and -15°C or lower, include structural units derived from 1-methylheptyl (meth)acrylate.

10. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, wherein, in at least one of the cases where the (meth)acrylic monomer contains 1-methylheptyl (meth)acrylate and the (meth)acrylic polymer has a structural unit derived from 1-methylheptyl (meth)acrylate, the total content of the 1-methylheptyl (meth)acrylate and the structural unit derived from 1-methylheptyl (meth)acrylate in the (meth)acrylic polymer is 60 mass% or more in the total of the (meth)acrylic monomer and the (meth)acrylic polymer.

11. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the (meth)acrylic polymer has a structural unit derived from a monomer having a crosslinkable functional group.

12. The pressure-sensitive adhesive composition according to claim 11, wherein the structural units derived from a monomer having a crosslinkable functional group include structural units derived from a hydroxyl group-containing monomer.

13. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, wherein, in at least one of the cases where the (meth)acrylic monomer contains a monomer having a crosslinkable functional group and the (meth)acrylic polymer has a structural unit derived from a monomer having a crosslinkable functional group, the total content of the monomer having a crosslinkable functional group and the structural unit in the (meth)acrylic polymer derived from the monomer having a crosslinkable functional group in the total of the (meth)acrylic monomer and the (meth)acrylic polymer is 0.01% by mass or more and 20% by mass or less.

14. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13, which contains a photopolymerization initiator.

15. The pressure-sensitive adhesive composition according to claim 14, wherein the photopolymerization initiator comprises a compound having two or more photopolymerization reaction sites.

16. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, which contains a tackifying resin.

17. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16, which contains a crosslinking agent.

18. The pressure-sensitive adhesive composition according to claim 17, wherein the crosslinking agent comprises at least one selected from the group consisting of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent.

19. The pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18, which contains a pigment.

20. The adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19, wherein the content of biologically derived carbon in the adhesive composition is 10% or more.

21. An adhesive tape having an adhesive layer containing a cured product of the adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

22. An adhesive tape having an adhesive layer containing a (meth)acrylic copolymer having structural units derived from an alkyl (meth)acrylate having a branched alkyl group, wherein the structural units derived from the alkyl (meth)acrylate having a branched alkyl group include structural units derived from an alkyl (meth)acrylate containing a branched alkyl group, the glass transition temperature of which, when made into a homopolymer, is -55°C or higher and -15°C or lower.

23. The pressure-sensitive adhesive tape according to claim 22, wherein the structural units derived from a branched alkyl group-containing alkyl (meth)acrylate, which when made into a homopolymer has a glass transition temperature of -55°C or higher and -15°C or lower, include structural units derived from 1-methylheptyl (meth)acrylate.

24. The adhesive tape according to claim 23, wherein the (meth)acrylic copolymer contains 60% by mass or more of structural units derived from 1-methylheptyl (meth)acrylate.

25. The adhesive tape according to claim 21, 22, 23 or 24, wherein the adhesive layer does not contain an organic solvent, or the adhesive layer contains an organic solvent and the content of the organic solvent in the adhesive layer is 5000 ppm or less.

26. The adhesive tape according to claim 21, 22, 23, 24 or 25, wherein the gel fraction of the adhesive layer is 10% by mass or more and 70% by mass or less.

27. The adhesive tape according to claim 21, 22, 23, 24, 25 or 26, which has a substrate layer.

28. The adhesive tape according to claim 21, 22, 23, 24, 25, 26 or 27, which is used to fasten electronic equipment parts or vehicle-mounted parts.

29. A method for producing an adhesive tape, comprising the step of curing the adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 by irradiating it with light.

Images