Adhesive, adhesive composition, adhesive sheet, laminate, and device with adhesive layer

Abstract

Disclosed is an adhesive which is a resin (A) that is a copolymer of a monomer mixture, wherein: 30 mass% or more and less than 99.5 mass% of 2-octyl (meth)acrylate and 0.1 mass% or more and less than 40 mass% of a monomer that has a hydroxy group are contained in 100 mass% of the monomer mixture; and in 100 mass% of the monomer mixture, the content of a monomer that has a carboxy group is less than 0.5 mass% and the content of monomers other than the 2-octyl (meth)acrylate, the monomer that has a hydroxy group, and the monomer that has a carboxy group is 55 mass% or less.

Description

Adhesive and adhesive composition, adhesive sheet, laminate and device with adhesive layer

[0001] The present disclosure relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, a laminate, and a device with a pressure-sensitive adhesive layer.

[0002] Because adhesive sheets having an adhesive layer formed from an adhesive are easy to handle, they are used in a wide range of fields, including label applications and medical applications. Furthermore, adhesive layers are used to bond components together to secure various devices, such as personal computers, mobile phones, and home appliances. Adhesive sheets used to secure devices require a minimum level of adhesive strength to prevent peeling during long-term use, as well as heat resistance to withstand high temperatures. Furthermore, when adhesive sheets are bonded to metal substrates, corrosion of the substrate due to components contained in the adhesive can cause product degradation, so adhesives with corrosion resistance are required.

[0003] On the other hand, for convenient coating during the preparation of adhesive sheets, adhesives are generally diluted and adjusted to a low viscosity before use. Regarding the solvent used for viscosity adjustment, it is desirable to reduce the content as much as possible from the viewpoints of cost and handling. Furthermore, if the solid content of the prepared solution is low, it tends to be difficult to apply the adhesive thickly and uniformly, so there is a demand for low-viscosity adhesives that can be made to have a higher solid content. The adhesives described in Patent Document 1 and Patent Document 2 are each adjusted to a solid content of about 35%.

[0004] Furthermore, as electronic devices become smaller and more highly integrated, there is a need to suppress the penetration of electromagnetic waves into the devices. For example, the adhesive tape described in Patent Document 3 had insufficient electromagnetic wave shielding performance. In order to improve the electromagnetic wave shielding effect, it is necessary to make the adhesive conductive, and increasing the dielectric constant of the adhesive is a useful method for improving the conductivity.

[0005] JP 2007-264092 A JP 2012-173354 A International Publication No. 2015-076174

[0006] In addition to the increasing performance requirements, industries using pressure-sensitive adhesive sheets are facing concerns about the depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products. Therefore, efforts to conserve petroleum resources by replacing petroleum-derived materials have been underway in various industries, starting with packaging, optics, and semiconductors. One method for increasing the proportion of bio-derived materials in pressure-sensitive adhesives primarily composed of acrylic polymers is to obtain an acrylic polymer by copolymerizing a monomer mixture containing a (meth)acrylic acid alkyl ester monomer obtained by esterifying a linear alkyl alcohol produced by living organisms with (meth)acrylic acid. Furthermore, there are also tackifying resins made from naturally derived components, and selective use of these can lead to the creation of environmentally friendly products. Increasing the proportion of environmentally friendly materials can contribute to further conserving petroleum resources, but the use of limited environmentally friendly materials poses challenges to practical application.

[0007] Furthermore, the inventors' investigations revealed that with the adhesives described in Patent Documents 1 and 2, when the solid content was adjusted to 35% or more, the viscosity became too high, making coating difficult, and it was not possible to increase the solid content, which resulted in major issues such as the high cost of the solvent used and the difficulty of applying a thick layer of adhesive.

[0008] The problem that the present disclosure aims to solve is to provide an adhesive that can contribute to the conservation of petroleum resources by increasing the proportion of environmentally friendly materials, and that has heat resistance, a high dielectric constant, excellent corrosion resistance, and a low viscosity adhesive that is capable of high solidification, as well as an adhesive sheet, laminate, and device with an adhesive layer that use the same.

[0009] After extensive research, the present inventors have found that the problems of the present invention can be solved in the following aspect, and have thus completed the present invention. Specifically, the present disclosure relates to a pressure-sensitive adhesive comprising a resin (A) that is a copolymer of a monomer mixture, the resin (A) containing, based on 100% by mass of the monomer mixture, 30% by mass or more but less than 99.5% by mass of 2-octyl(meth)acrylate and 0.1% by mass or more but less than 40% by mass of a monomer having a hydroxy group, wherein the content of the monomer having a carboxy group in 100% by mass of the monomer mixture is less than 0.5% by mass, and the content of other monomers other than 2-octyl(meth)acrylate, the monomer having a hydroxy group, and the monomer having a carboxy group is 55% by mass or less.

[0010] The present disclosure makes it possible to provide an adhesive that can contribute to the conservation of petroleum resources, and that has both heat resistance and a high dielectric constant, and a low viscosity adhesive capable of high solidification, as well as an adhesive sheet, a laminate, and a device with an adhesive layer that use the same.

[0011] Fig. 1 is a schematic cross-sectional view partially showing an example of a laminate of the present disclosure, Fig. 2 is a schematic cross-sectional view partially showing an example of a device with an adhesive layer of the present disclosure, Fig. 3 is a schematic cross-sectional view partially showing an example of an adhesive sheet of the present disclosure.

[0012] The pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet, and device including a pressure-sensitive adhesive layer according to the present disclosure have the following configurations [1] to

[17] .

[0013] [1] A pressure-sensitive adhesive, comprising a resin (A) that is a copolymer of a monomer mixture, the resin (A) containing, per 100% by mass of the monomer mixture, 30% by mass or more but less than 99.5% by mass of 2-octyl(meth)acrylate and 0.1% by mass or more but less than 40% by mass of a monomer having a hydroxy group, wherein the content of the monomer having a carboxy group in 100% by mass of the monomer mixture is less than 0.5% by mass, and the content of other monomers other than 2-octyl(meth)acrylate, the monomer having a hydroxy group, and the monomer having a carboxy group is 55% by mass or less. [2] The pressure-sensitive adhesive, the pressure-sensitive adhesive containing, per 100% by mass of the monomer mixture, 30% by mass or more but less than 90% by mass of 2-octyl(meth)acrylate and 10% by mass or more but less than 40% by mass of the monomer having a hydroxy group. [3] The pressure-sensitive adhesive having a biomass degree of 30% or more. [4] A pressure-sensitive adhesive composition comprising the pressure-sensitive adhesive and a curing agent (B). [5] The pressure-sensitive adhesive composition, wherein the curing agent (B) comprises at least one of an isocyanate-based curing agent and an epoxy-based curing agent. [6] The pressure-sensitive adhesive composition, further comprising a silane coupling agent (C). [7] The pressure-sensitive adhesive composition, wherein the gel fraction is 40% or more. [8] The pressure-sensitive adhesive composition, further comprising less than 50 parts by mass of a tackifier resin (D) per 100 parts by mass of the resin (A). [9] The pressure-sensitive adhesive composition, wherein the tackifier resin (D) has a biomass content of 80% or more.

[10] A pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive or the pressure-sensitive adhesive composition.

[11] The pressure-sensitive adhesive layer, wherein the dielectric constant at 20 GHz is 0.5 or more.

[12] The pressure-sensitive adhesive layer, wherein the SUS adhesive strength is 3 N / 25 mm or more.

[13] A pressure-sensitive adhesive sheet, comprising the pressure-sensitive adhesive layer and a release film.

[14] The pressure-sensitive adhesive sheet, wherein the release film has a thickness of less than 200 μm.

[15] A laminate, comprising the pressure-sensitive adhesive layer and a substrate.

[16] The laminate, wherein the thickness of the substrate is less than 500 μm.

[17] A device with a pressure-sensitive adhesive layer, comprising the pressure-sensitive adhesive layer and a device.

[0014] The composition, pressure-sensitive adhesive sheet, laminate, and device of the present disclosure are described below, but are not limited thereto. In this specification, (meth)acrylate collectively refers to acrylate and methacrylate, respectively, and (meth)acryloxy group collectively refers to acryloxy group and methacryloxy group, respectively. A monomer is a monomer having an ethylenically unsaturated group. In this specification, a numerical range specified using "to" includes the numerical values ​​before and after "to" as the lower and upper limits of the range. Furthermore, "film" and "sheet" are not distinguished by thickness. In other words, in this specification, "sheet" includes thin film-like objects, and "film" in this specification includes thick sheet-like objects. Furthermore, an adherend refers to the object to which the pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet is attached. Unless otherwise noted, the various components mentioned in this specification may be used independently, either singly or in combination of two or more types.

[0015] <<Adhesive>> The adhesive of the present disclosure is a resin (A). The resin (A) can be used substantially alone as an adhesive. One embodiment of the adhesive is as follows.

[0016] The adhesive is a resin (A) that is a copolymer of a monomer mixture, containing, per 100% by mass of the monomer mixture, 30% by mass or more but less than 99.5% by mass of 2-octyl(meth)acrylate and 0.1% by mass or more but less than 40% by mass of a monomer having a hydroxy group, wherein the content of the monomer having a carboxy group in 100% by mass of the monomer mixture is less than 0.5% by mass, and the content of other monomers other than 2-octyl(meth)acrylate, the monomer having a hydroxy group, and the monomer having a carboxy group is 55% by mass or less. Resin (A) will be described below.

[0017] <Resin (A)> Resin (A) is a copolymer of a monomer mixture. The monomer mixture contains 2-octyl (meth)acrylate and a monomer having a hydroxy group, and may optionally contain a monomer having a carboxy group. The monomer mixture may further optionally contain other monomers other than these. Each monomer will be described below.

[0018] [2-Octyl (meth)acrylate] 2-Octyl (meth)acrylate is a biomass monomer represented by the following formula (1): (Formula 1)

[0019] In formula 1, R1 is a hydrogen atom (H) or CH ３ is.

[0020] The content of 2-octyl (meth)acrylate is 30% by mass or more and less than 99.5% by mass based on 100% by mass of the monomer mixture. A content of 2-octyl (meth)acrylate less than 30% by mass is undesirable because it may increase the viscosity of the PSA or decrease its adhesive strength. The lower limit of the 2-octyl (meth)acrylate content is 30% by mass or more to achieve the desired effect, but is preferably 50% by mass or more, and more preferably 70% by mass or more. A higher 2-octyl (meth)acrylate content is preferable because it contributes to the conservation of petroleum resources. However, in relation to the content of the hydroxyl group-containing monomer, a content of less than 90% by mass is preferred, and more preferably less than 80% by mass. For example, the content of 2-octyl (meth)acrylate may be 30% by mass or more and less than 99.5% by mass, 50% by mass or more and less than 90% by mass, or 70% by mass or more and less than 80% by mass based on 100% by mass of the monomer mixture.

[0021] [Monomer Having a Hydroxy Group] The monomer having a hydroxy group is not limited as long as it is a monomer having a hydroxy group in the molecule, and specific examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Of these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred from the viewpoints of adhesive strength and heat resistance.

[0022] The content of the monomer having a hydroxy group is 0.1% by mass or more and less than 40% by mass based on 100% by mass of the monomer mixture. It is preferably 10% by mass or more and less than 40% by mass, and more preferably 20% by mass or more and less than 40% by mass. By making the content of the monomer having a hydroxy group 0.1% by mass or more, it is possible to promote curing and prevent whitening under moist heat. Furthermore, by making the content of the hydroxy group less than 40% by mass, it is possible to suppress an increase in the viscosity of the solution.

[0023] [Monomer Having a Carboxy Group] The monomer having a carboxy group is not limited as long as it is a monomer having a carboxy group in the molecule, and specific examples include (meth)acrylic acid, p-carboxybenzyl acrylate, β-carboxyethyl acrylate, maleic acid, monoethyl maleate, itaconic acid, citraconic acid, fumaric acid, etc. Of these, (meth)acrylic acid is preferred from the viewpoint of adhesive strength, and acrylic acid is more preferred.

[0024] The monomer having a carboxy group may or may not be contained, but if it is contained, the content is less than 0.5 mass% of 100 mass% of the monomer mixture to prevent corrosion of the adherend by acid. The inclusion of the monomer having a carboxy group increases the cohesive strength of the adhesive layer, making it easier to improve adhesive strength and heat resistance. For example, the content of the monomer having a carboxy group in 100 mass% of the monomer mixture may be 0.05 mass% or more but less than 0.5 mass%, 0.1 mass% or more but 0.4 mass% or less, or 0.2 mass% or more but 0.3 mass% or less.

[0025] [Other Monomers] The other monomers are not particularly limited as long as they are monomers other than 2-octyl (meth)acrylate, monomers having a hydroxy group, and monomers having a carboxy group. In addition, in consideration of the environment, it is preferable to use (meth)acrylates, which are biomass monomers, as the other monomers, and it is more preferable to use (meth)acrylates with a high biomass content.

[0026] Examples of other monomers include acrylic monomers having an amide group such as acrylamide, N,N-dimethylacrylamide, and diacetone acrylamide; nitrile group-containing monomers such as methacrylonitrile and acrylonitrile; acrylate monomers having an alkyl group such as methyl (meth)acrylate, ethyl methacrylate, ter-butyl methacrylate, sec-butyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, isopropyl methacrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, and cyclohexyl (meth)acrylate; acrylate monomers having an aromatic ring such as benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and phenyl (meth)acrylate; monomers having a cyclic amide group such as 4-acryloylmorpholine and vinylimidazole; and high Tg monomers such as vinyl acetate. From the viewpoint of improving cohesive strength and adhesive strength, the high Tg monomer is preferably selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyl (meth)acrylate, 4-acryloylmorpholine, and vinyl acetate. Among these, it is more preferable to use isobornyl (meth)acrylate, which is a biomass monomer.

[0027] The other monomer may or may not be contained, but if it is contained, the content is 55% by mass or less relative to 100% by mass of the monomer mixture. By setting this content to 55% by mass or less, an increase in viscosity of the PSA can be suppressed. In terms of suppressing viscosity increase, the content is preferably 40% by mass or less, more preferably 20% by mass or less. On the other hand, by setting this content to 0.1% by mass or more, performance specific to that monomer can be imparted. For example, a high Tg monomer can impart cohesive strength, and a biomass monomer can improve the overall biomass content. The content is preferably 1% by mass or more, more preferably 5% by mass or more. For example, the other monomer may be 0.1 to 55% by mass, 1 to 40% by mass, or 5 to 20% by mass relative to 100% by mass of the monomer mixture.

[0028] (Production of Resin (A)) Resin (A) can be produced by polymerizing a monomer mixture. Although known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization are possible, solution polymerization is preferred. Preferred solvents used in solution polymerization include, for example, acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, and cyclohexanone. The polymerization temperature is preferably a boiling point reaction at 60 to 120°C. The polymerization time is preferably about 5 to 12 hours.

[0029] The polymerization initiator used in the polymerization is preferably a radical polymerization initiator. Radical polymerization initiators are generally peroxides and azo compounds. Examples of peroxides include dialkyl peroxides such as di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, and 2,5-di(t-butylperoxy)hexyne-3; peroxy esters such as t-butyl peroxybenzoate, t-butyl peroxyacetate, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane; ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane; Examples of the peroxyketals include 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, and n-butyl-4,4-bis(t-butylperoxy)valerate; hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, and 2,5-dimethylcyclohexane-2,5-dihydroperoxide; diacyl peroxides such as benzoyl peroxide, decanoyl peroxide, lauroyl peroxide, and 2,4-dichlorobenzoyl peroxide; and peroxydicarbonates such as bis(t-butylcyclohexyl)peroxydicarbonate.

[0030] Examples of the azo compound include 2,2'-azobisbutyronitrile such as 2,2'-azobisisobutyronitrile (abbreviation: AIBN) and 2,2'-azobis(2-methylbutyronitrile); 2,2'-azobisvaleronitrile such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile); 2,2'-azobispropionitrile such as 2,2'-azobis(2-hydroxymethylpropionitrile); and 1,1'-azobis-1-alkanenitrile such as 1,1'-azobis(cyclohexane-1-carbonitrile).

[0031] The polymerization initiator is preferably used in an amount of 0.01 to 10 parts by mass, more preferably 0.1 to 2 parts by mass, based on 100 parts by mass of the monomer mixture.

[0032] (Weight-average molecular weight (Mw)) The weight-average molecular weight of the resin (A) is not particularly limited, but is preferably 2,000,000 or less, and more preferably 1,000,000 or less. The weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0033] <<Pressure-Sensitive Adhesive Composition>> The pressure-sensitive adhesive composition of the present disclosure contains a pressure-sensitive adhesive resin (A) and a curing agent (B). It may also contain a silane coupling agent (C) and a tackifying resin (D) as needed.

[0034] <Curing Agent (B)> The pressure-sensitive adhesive composition of the present disclosure contains a curing agent (B), and the curing agent (B) can be any curing agent that can provide a crosslinked structure to the pressure-sensitive adhesive composition. The incorporation of a curing agent improves the cohesive strength of the pressure-sensitive adhesive layer, thereby improving adhesive strength, heat resistance, and light resistance. The curing agent (B) preferably contains at least one of an isocyanate-based curing agent and an epoxy-based curing agent. The inclusion of at least one of an isocyanate-based curing agent and an epoxy-based curing agent is preferable in that it can appropriately increase the cohesive strength of the pressure-sensitive adhesive and is less likely to adversely affect other physical properties. As long as the pressure-sensitive adhesive composition contains at least one of an isocyanate-based curing agent and an epoxy-based curing agent, known curing agents other than an isocyanate-based curing agent and an epoxy-based curing agent may be used in combination.

[0035] The isocyanate curing agent is an isocyanate having two or more isocyanate groups. Examples of the isocyanate include aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, alicyclic polyisocyanates, and their biuret forms, nurate forms, and adduct forms, and from the viewpoint of yellowing resistance, aliphatic polyisocyanates, alicyclic polyisocyanates, and their biuret forms, nurate forms, and adduct forms are more preferred.

[0036] Examples of aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4"-triphenylmethane triisocyanate.

[0037] Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0038] Examples of the aromatic aliphatic polyisocyanate include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.

[0039] Examples of alicyclic polyisocyanates include 3-isocyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanatemethyl)cyclohexane.

[0040] The biuret compound is a self-condensation product having a biuret bond formed by self-condensation of an isocyanate monomer, such as a biuret compound of hexamethylene diisocyanate.

[0041] The nurate derivative is a trimer of an isocyanate monomer, such as a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, or a trimer of tolylene diisocyanate.

[0042] The adduct is a difunctional or higher isocyanate compound obtained by reacting an isocyanate monomer with a difunctional or higher low-molecular-weight active hydrogen-containing compound. Examples of the adduct include a compound obtained by reacting trimethylolpropane with hexamethylene diisocyanate, a compound obtained by reacting trimethylolpropane with tolylene diisocyanate, a compound obtained by reacting trimethylolpropane with xylylene diisocyanate, a compound obtained by reacting trimethylolpropane with isophorone diisocyanate, and a compound obtained by reacting 1,6-hexanediol with hexamethylene diisocyanate.

[0043] The isocyanate compound is preferably a trifunctional isocyanate compound from the viewpoint of forming a sufficient crosslinked structure. The isocyanate compound is more preferably an adduct or nurate, which is a reaction product of an isocyanate monomer and a trifunctional low-molecular-weight active hydrogen-containing compound. The isocyanate compound is preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a nurate of hexamethylene diisocyanate, a trimethylolpropane adduct of tolylene diisocyanate, a nurate of tolylene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate, or a nurate of isophorone diisocyanate, and more preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of tolylene diisocyanate, or a trimethylolpropane adduct of isophorone diisocyanate.

[0044] Examples of epoxy curing agents include glycerin diglycidyl ether, 1,6-hexanediol diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidylaminophenylmethane.

[0045] The curing agent (B) is preferably contained in an amount of 0.02 to 4 parts by mass, and more preferably 0.04 to 1 part by mass, per 100 parts by mass of the resin (A). When the content is 0.02 part by mass or more, the cohesive strength is further improved, and when it is 4 parts by mass or less, it becomes easier to achieve both cohesive strength and flexibility, making it easier to obtain sufficient adhesive strength, heat resistance, and light resistance.

[0046] <Silane Coupling Agent (C)> The pressure-sensitive adhesive composition of the present disclosure preferably contains a silane coupling agent (C). By including the silane coupling agent (C), it is possible to improve adhesive strength, heat resistance, resistance to wet heat whitening, and light fastness. The silane coupling agent (C) is preferably included in an amount of 0.05 to 0.2 parts by mass per 100 parts by mass of the resin (A). By including the silane coupling agent (C) in an amount of 0.05 to 0.2 parts by mass, it becomes easy to achieve both heat resistance, outgassing resistance, and light fastness.

[0047] Examples of the silane coupling agent (C) include alkoxysilane compounds having a (meth)acryloxy group, alkoxysilane compounds having a vinyl group, alkoxysilane compounds having an amino group, alkoxysilane compounds having a mercapto group, and alkoxysilane compounds having an epoxy group. Specific examples of commercially available products include KBM-403 (3-glycidoxypropyltrimethoxysilane), KBE-403 (3-glycidoxypropyltriethoxysilane), KBM-303 (2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane) (all manufactured by Shin-Etsu Chemical Co., Ltd.), and BYK-325N (polyether-modified polymethylalkylsiloxane) (manufactured by BYK Japan KK).

[0048] <Tackifier Resin (D)> The pressure-sensitive adhesive composition of the present disclosure preferably further contains a tackifier resin (D). As the tackifier resin (D), any of the existing resins can be used, such as aliphatic petroleum resins, aromatic petroleum resins, synthetic hydrocarbon resins, terpene resins, rosin resins (rosin, polymerized rosin, hydrogenated rosin, and their esters with glycerin, pentaerythritol, etc., resin acid dimers, etc.), and acrylic resins. The tackifier resin may be used alone or in combination of two or more.

[0049] Examples of aliphatic petroleum resins include Quinton B170 manufactured by Zeon Corporation; examples of aromatic petroleum resins include Nippon Oil Neopolymer L-90 manufactured by JXTG; examples of aliphatic / aromatic petroleum resins include FTR6100 manufactured by Mitsui Chemicals, Inc.; and examples of rosin derivatives include SylvatacRE85 manufactured by Arizona Chemical Company and Superester A-75 manufactured by Arakawa Chemical Industries, Ltd.

[0050] Examples of synthetic hydrocarbon resins include aliphatic petroleum resins, aromatic petroleum resins, aliphatic / aromatic petroleum resins, hydrogenated petroleum resins, coumarone-indene resins, and phenol resins.

[0051] Examples of terpene resins include α-pinene resins, β-pinene resins, dipentene resins, aromatic modified terpene resins, hydrogenated terpene resins, terpene phenol resins, acid modified terpene resins, styrenated terpene resins, and styrene-aliphatic hydrocarbon copolymer resins.

[0052] Examples of rosin-based resins include rosin ester, polymerized rosin, hydrogenated rosin, disproportionated rosin, maleic acid-modified rosin, fumaric acid-modified rosin, rosin phenolic resin, and natural rosin.

[0053] The content of the tackifier resin (D) is preferably less than 50 parts by mass, and more preferably 40 parts by mass or less, per 100 parts by mass of the resin (A) in the pressure-sensitive adhesive composition. By including the tackifier resin (D), the adhesive strength to the adherend can be improved.

[0054] In consideration of the environment, it is more preferable to use a tackifier resin (D) having a biomass content of 80% or more. The softening point of the tackifier resin (D) is preferably a high-softening-point grade, from the viewpoint of improving heat resistance, and is preferably 90°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher.

[0055] The pressure-sensitive adhesive composition of the present disclosure may contain various resins, chlorinated polyolefins described below, oils, softeners, dyes, pigments, antioxidants, and ultraviolet absorbers as optional components, as long as the problem can be solved.

[0056] Examples of chlorinated polyolefins include chlorinated polypropylene, acid-modified chlorinated polypropylene, acrylic-modified chlorinated polypropylene, chlorinated polyethylene, and chlorinated ethylene-vinyl acetate copolymers, among which chlorinated polypropylene and chlorinated ethylene-vinyl acetate copolymers are preferred from the viewpoints of good compatibility with acrylic polymers and the like and effective reduction of polarity. Specific examples of commercially available products include Superchlor 390S (chlorinated polypropylene, chlorine content 36%) and Superchlor BX (chlorinated EVA, chlorine content 18%) (both manufactured by Nippon Paper Industries Co., Ltd.).

[0057] The pressure-sensitive adhesive composition of the present disclosure preferably has a gel fraction of 40% or more. However, depending on the application, a gel fraction of 40% or less may also be used. The method for measuring the gel fraction will be described in detail in the Examples.

[0058] The pressure-sensitive adhesive composition of the present disclosure contains resin (A), a copolymer of a monomer mixture containing a specific monomer, which suppresses viscosity increases when using a polymer and ensures high adhesive strength to adherends. This allows for a significant reduction in the amount of organic solvent used to adjust viscosity during application compared to conventional methods. In the present disclosure, when the weight-average molecular weight of resin (A) is 1.9 million to 2 million, the viscosity at a solids content of 15% (±1%) is preferably 3,000 mPas·s or less; when it is 700,000 to 900,000, the viscosity at a solids content of 35% (±1%) is preferably 3,000 mPas·s or less; and when it is 400,000 to 500,000, the viscosity at a solids content of 50% (±1%) is preferably 3,000 mPas·s or less. Details of the method for preparing the solids and the method for measuring the viscosity are described in the Examples.

[0059] <<Pressure-Sensitive Adhesive Layer>> The pressure-sensitive adhesive layer is a layer obtained using the pressure-sensitive adhesive or pressure-sensitive adhesive composition of the present disclosure. The method for forming the pressure-sensitive adhesive layer is not particularly limited, and may be the same as the coating method described below in the description of the pressure-sensitive adhesive sheet.

[0060] The pressure-sensitive adhesive layer of the present disclosure preferably has a dielectric constant of 0.5 or more at 20 GHz, more preferably 2.0 or more. A dielectric constant within this range at 20 GHz can impart conductivity to the pressure-sensitive adhesive, thereby enhancing the electromagnetic wave shielding effect. The unit of dielectric constant is (F / m). In order to achieve a dielectric constant within this range, it is necessary to increase the polarity of the pressure-sensitive adhesive. It is necessary to use a compound that is inherently highly polar, or to reduce the number of carbon atoms contained in the compound. The measurement method will be described in detail in the Examples.

[0061] The adhesive sheet of the present disclosure preferably has a higher SUS adhesive strength for the purpose of product fixation, etc. Although a lower adhesive strength may be used depending on the product, for versatile use, a peel strength of 3 N / 25 mm or more is preferred. The measurement method will be described in detail in the Examples.

[0062] <<Adhesive Sheet>> The adhesive sheet comprises an adhesive layer made of the adhesive or adhesive composition of the present disclosure and a release film.

[0063] The pressure-sensitive adhesive sheet of the present disclosure may have a configuration in which a release film is formed on one or both sides of the pressure-sensitive adhesive layer.

[0064] <Release Film> The release film is not particularly limited, but a transparent plastic substrate can be suitably used. Examples of materials for the transparent plastic substrate include polyesters such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), and plastic materials such as polycarbonate, triacetyl cellulose, polysulfone, polyarylate, and polycycloolefin. The plastic materials can be used alone or in combination of two or more.

[0065] As the release film, among the transparent plastic substrates described above, a transparent plastic substrate having excellent heat resistance, i.e., a transparent plastic substrate that is suppressed or prevented from deforming under severe conditions such as high temperature, high temperature and high humidity, etc. PET film or sheet is particularly suitable as the transparent plastic substrate.

[0066] The thickness of the release film is preferably less than 200 μm. The thickness should be adjusted depending on the handling of the member to be used, but by being less than 200 μm, the material itself is not too stiff, making it easy to wind up into a roll and allowing for comfortable use when laminating sheets or the like.

[0067] The pressure-sensitive adhesive sheet of the present disclosure has excellent heat resistance and a high dielectric constant, and can therefore be used for fixing the exterior or interior of various devices such as personal computers, mobile phones, home appliances, etc. It can also be used to fix, without particular limitation, materials different from the device, such as polyolefins including polyethylene and polypropylene, resins such as polycarbonate and phenol, metals such as iron, stainless steel (SUS), aluminum and copper, cement, mortar, glass, nonwoven fabrics, woven fabrics, paper, rubber, foam sheets, etc.

[0068] When applying the adhesive or adhesive composition, viscosity can be adjusted by adding a suitable liquid medium.Specific examples include hydrocarbon solvents such as toluene, xylene, hexane, and heptane; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone and methyl ethyl ketone; halogenated hydrocarbon solvents such as dichloromethane and chloroform; ether solvents such as diethyl ether, methoxytoluene, and dioxane, or other hydrocarbon solvents.However, water and alcohols should be used carefully because they may inhibit the reaction between the resin (A) and the isocyanate curing agent.

[0069] The coating method is not particularly limited, and examples thereof include various coating methods using a Mayer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin coater, etc. The drying and curing method is also not particularly limited, and examples thereof include hot air drying, infrared rays, reduced pressure methods, and methods using active energy rays, but hot air or steam heating at 60 to 180°C is preferred from the viewpoint of outgassing resistance.

[0070] The thickness of the adhesive layer is preferably 2 to 1000 μm, more preferably 5 to 500 μm. The adhesive layer may be in the form of a single layer or a laminate of two or more layers.

[0071] <Laminate> The laminate of the present disclosure includes a substrate and a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer is formed using the pressure-sensitive adhesive sheet of the present disclosure. Specifically, for example, the laminate can be formed by peeling the release film from the pressure-sensitive adhesive sheet of the present disclosure and attaching the pressure-sensitive adhesive layer to the substrate.

[0072] <Substrate> The substrate refers to the surface to which the pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer is attached, and is not limited to a specific material. Examples of suitable substrates include polyolefins such as polyethylene and polypropylene, resins such as polycarbonate and phenol, metals such as iron, stainless steel (SUS), aluminum, and copper, cement, mortar, glass, nonwoven fabric, woven fabric, paper, rubber, foam sheets, and laminates thereof. The pressure-sensitive adhesive and pressure-sensitive adhesive composition of the present disclosure exhibit excellent adhesive strength to at least one type of adherend. The thickness of the substrate is not particularly limited, and is preferably less than 500 μm, more preferably 10 to 200 μm, and even more preferably 25 to 150 μm.

[0073] An example of a schematic cross-sectional view partially showing the laminate of the present disclosure is shown in Fig. 1. In Fig. 1, 3 is a substrate, 1 is a pressure-sensitive adhesive layer, and 4 is a device 1.

[0074] In the laminate shown in FIG. 1, the substrate is attached to the device 1 via an adhesive layer.

[0075] <Production of Laminate> The method for producing a laminate can be, for example, to peel off a release film on one side of a pressure-sensitive adhesive layer from a pressure-sensitive adhesive sheet having release films on both sides thereof, and then attach the pressure-sensitive adhesive layer to a substrate to form a laminate. Alternatively, a pressure-sensitive adhesive layer can be directly formed on a substrate, and then a pressure-sensitive adhesive layer provided on the substrate or another pressure-sensitive adhesive sheet can be attached to the pressure-sensitive adhesive layer to form a laminate.

[0076] <Device with Adhesive Layer> The device with an adhesive layer of the present disclosure is not particularly limited as long as it includes the above-described adhesive layer and device. The device with an adhesive layer can be produced, for example, using the adhesive sheet or laminate of the present disclosure. That is, it may have a configuration such as adhesive layer / device or substrate / adhesive layer / device. Alternatively, it may have a configuration such as device 1 / adhesive layer / device 2, in which different devices 1 and 2 are bonded together via an adhesive layer.

[0077] Figure 2 shows an example of a schematic cross-sectional view partially illustrating a device with a pressure-sensitive adhesive layer, which is an example of use of the pressure-sensitive adhesive sheet of the present disclosure. In Figure 2, 1 is the pressure-sensitive adhesive layer, 4 is device 1, and 5 is device 2. It should be noted that the configuration of the device with a pressure-sensitive adhesive layer is not limited to that shown in Figure 2.

[0078] Figure 3 shows an example of a schematic cross-sectional view partially illustrating a device with a pressure-sensitive adhesive layer, which is another example of use of the pressure-sensitive adhesive sheet of the present disclosure. In Figure 3, 1 is a pressure-sensitive adhesive layer, 2 is a release film, and 3 is a substrate. In the device with a pressure-sensitive adhesive layer shown in Figure 3, the substrate is attached to the release film via the pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) of the present disclosure. In this way, the device can be commercialized in a state where the release film is provided, or can be used in an intermediate process of commercialization.

[0079] The use of the device with the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include all home appliances such as personal computers, mobile phones, televisions, tablets, and smart watches.

[0080] In light of the recent trend toward environmentally friendly materials, the adhesive and adhesive composition of the present disclosure can be made partially or entirely from biologically derived materials by using a biomass monomer as the monomer constituting the resin (A) or by using a biomass tackifier. The biomass ratio is preferably 30% or more. The higher the biomass ratio, more preferably 39% or more, and even more preferably 60% or more, the greater the usefulness as an environmentally friendly material. The method for calculating the biomass ratio is described in the Examples.

[0081] The present disclosure will be further described in detail below using examples, but the present disclosure is not limited to these examples. In the examples, unless otherwise specified, "parts" and "%" refer to "parts by mass" and "% by mass," respectively. Furthermore, the blending amounts in the tables are in parts by mass, and values ​​other than the solvent are calculated as nonvolatile components. Blank spaces in the tables indicate no blending. It is common technical knowledge that the viscosity of a pressure-sensitive adhesive composition increases or decreases depending on the Mw of the resin (A) contained therein. Since the Mw of resin (A) can be adjusted as appropriate, it is not realistic to verify the effects of the present disclosure across the entire Mw range of resin (A). Therefore, in the examples, resin (A) was produced and evaluated so that its Mw was 400,000 to 500,000, 700,000 to 900,000, or 1,900,000 to 2,000,000. The method for measuring the weight-average molecular weight of resin (A) is as follows:

[0082] <Method for measuring weight-average molecular weight (Mw) and evaluating Mw classification> The weight-average molecular weight (Mw) was measured by gel permeation chromatography (GPC). The apparatus used was a GPC apparatus manufactured by Shimadzu Corporation: LC-GPC system "Prominence". Furthermore, a TSKgel α-M manufactured by Tosoh Corporation was used as the column, and two columns were connected in series. N,N-dimethylformamide (DMF) was used as the eluent, and measurements were taken at 40°C. Mw was determined by conversion using polystyrene with a known Mw as the standard substance. The weight-average molecular weight (Mw) of resin (A) was measured, and the evaluation results were as follows: if it was 1.9 million to 2 million, the Mw classification was U; if it was 700,000 to 900,000, the Mw classification was H; and if it was 400,000 to 500,000, the Mw classification was L.

[0083] (Production of Resin (A)) Example 1: Production of (A-1) Using a reaction apparatus equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping tube, ethyl acetate was added to a reaction vessel as a polymerization solvent, and a monomer mixture of 19.75 parts of 2-octyl acrylate (2-OA), 7 parts of 2-hydroxyethyl acrylate (HEA), and 0.25 parts of 4-hydroxybutyl acrylate (4HBA), 20 parts of methyl acrylate (MA), 3 parts of isobornyl acrylate (IBXA), and 0.04 parts of azobisisobutyronitrile as an initiator was charged into a reaction vessel. A solution containing a monomer mixture of 19.75 parts of 2-octyl acrylate (2-OA), 7 parts of 2-hydroxyethyl acrylate (HEA), 0.25 parts of 4-hydroxybutyl acrylate (4HBA), 20 parts of methyl acrylate (MA), and 3 parts of isobornyl acrylate (IBXA), ethyl acetate as a polymerization solvent, and 0.02 parts of azobisisobutyronitrile as an initiator, was added dropwise from the dropping tube over approximately 2 hours and polymerized for 6 hours at approximately 80°C under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a resin solution. The resulting resin was designated (A-1). The weight-average molecular weight (Mw) of the resulting resin was measured, and the results are shown in Table 1.

[0084] <Production of Examples 2 to 19, Examples 53 to 60, and Comparative Production Examples 1 to 5 (A-2 to A-19, A'-1 to A'-5)> Resins (A-2 to A-19, A'-1 to A'-5) were produced in the same manner as in the production of the resin (Example 1), except that the compositions and blending amounts (parts by mass) were changed to those shown in Tables 1 to 3. The Mw classifications of the obtained resins are shown in Tables 1 to 3.

[0085]

[0086]

[0087]

[0088] The abbreviations are as follows. Only confirmed biomass degrees are listed. [2-Octyl (meth)acrylate] 2-OA: 2-octyl acrylate (biomass degree 73%) 2-OMA: 2-octyl methacrylate (biomass degree 67%) [Monomers with hydroxy groups (OH monomers)] HEA: hydroxyethyl acrylate 4HBA: 4-hydroxy-normal-butyl acrylate HEAA: N-(2-hydroxyethyl)acrylamide

[0089] [Monomer having a carboxy group (COOH monomer)] AA: acrylic acid

[0090] [Other monomers] MA: methyl acrylate MMA: methyl methacrylate IBXA: isobornyl acrylate (biomass content 76%) BMA: butyl methacrylate 2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate (biomass content 57%) LA: lauryl acrylate (biomass content 80%) VAc: vinyl acetate ACMO: acryloylmorpholine BzA: benzyl acrylate

[0091] Example 20 A pressure-sensitive adhesive composition was obtained by blending 0.2 parts of "D-165N" (a biuret of hexamethylene diisocyanate manufactured by Mitsui Chemicals, Inc.) as the curing agent (B) with 100 parts of the resin (A-1). The resulting pressure-sensitive adhesive composition was applied using a comma coater to a 38 μm thick release liner (SP-PET-O1-BU, manufactured by Mitsui Chemicals Tohcello, Inc.) as a release sheet so that the thickness after drying would be 25 μm. After drying at 110°C for 3 minutes, a 75 μm thick release liner (SP-PET-O3-B3, manufactured by Mitsui Chemicals Tohcello, Inc.) as a release sheet was laminated to the pressure-sensitive adhesive layer, and the resulting mixture was aged in this state at 23°C for 7 days to obtain a pressure-sensitive adhesive sheet.

[0092] Examples 21 to 51, Examples 61 to 67, Example 69, Comparative Examples 1 to 5 As shown in Tables 4 and 5, pressure-sensitive adhesive compositions and pressure-sensitive adhesive sheets were obtained in the same manner as in Example 20, except that the types and blending amounts of the resin, curing agent (B), silane coupling agent (C), and tackifier resin (D) were changed.

[0093] Example 52 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 20, except that the resin (A-1) obtained in Example 1 was used as the pressure-sensitive adhesive.

[0094] Example 68 A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 20, except that a pressure-sensitive adhesive containing only the resin (A-24) obtained in Example 57 was used.

[0095] <Gel Fraction Measurement> The 38 μm release liner was peeled off from the obtained pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer was attached to a PET film substrate (Cosmoshine A-4360, manufactured by Toyobo Co., Ltd., thickness 100 μm), and the sheet was cut into a size of 30 mm wide x 100 mm long to prepare a test pressure-sensitive adhesive sheet. The release liner on the other side of the pressure-sensitive adhesive tape was then peeled off to prepare a test specimen, and its weight was measured. The test specimen was immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 150°C for 30 minutes. The weight of the test specimen after drying was measured, and the gel fraction was calculated using the following formula (1). In Tables 4 and 5, "40%<" means that the gel fraction is greater than 40%. Gel fraction (wt%)=100×(W2−W0) / (W1−W0) (1) (W0: weight of substrate (PET film), W1: weight of test piece before immersion, W2: weight of test piece after immersion and drying)

[0096] <Calculation of Biomass Degree> The biomass degree of the PSA composition was calculated using the following formula (2): (In the case of a system consisting of two monomer components (A, B) and one tackifier component (C)) Biomass degree = {(Aw x Ab) + (Bw x Bb) + (Cw x Cb)} / (Aw + Bw + Cw) (2) Aw: weight of monomer A, Bw: weight of monomer B, Cw: weight of tackifier, Ab: biomass degree (%) of monomer A, Bb: biomass degree (%) of monomer B, Cb: biomass degree (%) of monomer C. When the biomass degree was specified as a range, the minimum value was used for the calculation.

[0097] The materials used in the examples and comparative examples are listed below. <Curing agent (B)> D-165N: biuret of hexamethylene diisocyanate, manufactured by Mitsui Chemicals, Inc. Tetrad X: multifunctional epoxy resin, manufactured by Mitsubishi Gas Chemical Company, Inc. Aluminum Chelate A: chelate curing agent, manufactured by Kawaken Fine Chemicals Co., Ltd.

[0098] <Silane Coupling Agent (C)> KBE-403: (3-glycidoxypropyltriethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0099] <Tackifying Resin (D)> A-100: (Super Ester A-100, Arakawa Chemical Industries, Ltd., biomass content 95 to 100%, softening point 95°C to 105°C) YS-T160: (YS Polystar T160, Yasuhara Chemical Co., Ltd., biomass content 70%, softening point 160°C)

[0100] The pressure-sensitive adhesives and pressure-sensitive adhesive compositions obtained in Examples 20 to 52, Examples 61 to 69, and Comparative Examples 1 to 5 were evaluated for low viscosity, dielectric constant, heat resistance, and corrosion resistance by the methods described below. The adhesive strength of the pressure-sensitive adhesive layer to SUS was also measured. The results are shown in Tables 6 and 7.

[0101] <Low Viscosity> The viscosity of the pressure-sensitive adhesives and pressure-sensitive adhesive compositions of Examples 20 to 52, Examples 61 to 69, and Comparative Examples 1 to 5 was measured by the following method to evaluate low viscosity. When the weight average molecular weight (Mw) of the contained resin was 1.9 million to 2.0 million (U), the solids content was adjusted to 15% (±1); when the Mw was 700,000 to 900,000 (H), the solids content was adjusted to 35% (±1); and when the Mw was 400,000 to 500,000 (L), the solids content was adjusted to 50% (±1), and the viscosity was measured using a Brookfield viscometer (rotor number: M3, rotation speed: 12 rpm). The solids content was adjusted using ethyl acetate. [Evaluation criteria] A: Viscosity less than 3000 mPas·s: Good B: Viscosity 3000 mPas·s or more but less than 4000 mPas·s: Usable C: Viscosity 4000 mPas·s or more: Unusable

[0102] <Dielectric Constant> Samples were prepared by laminating 25 μm PET to both sides of the pressure-sensitive adhesive layer obtained in the Examples or Comparative Examples, and the dielectric constant (F / m) at a frequency of 20 GHz was measured using the following device. Three samples were prepared for each specimen, and the average of the measurements for these three samples was taken as the dielectric constant. After the measurement, the measurement value for the PET alone was subtracted from the measurement value for the three-layer structure of PET-pressure-sensitive adhesive layer-PET to obtain the measurement value for the pressure-sensitive adhesive layer itself. Measurement method: Cavity resonator method JIS R1641 IPC-TM650 2.5.5.13 Device: Dielectric constant measurement device, cavity resonator TE mode, manufactured by AET Corporation Measurement environment: 23±1°C, 52±1% RH [Evaluation criteria] A: Dielectric constant of 2.7 or more: Excellent B: Dielectric constant of 2.5 or more but less than 2.7: Good C: Dielectric constant of 0.5 or more but less than 2.5: Usable D: Dielectric constant less than 0.5: Unusable

[0103] <Heat Resistance> The obtained pressure-sensitive adhesive sheet was cut to a size of 25 mm wide and 100 mm long to prepare a test piece, and then the 38 μm release liner was peeled off from the test piece in an atmosphere of 23°C and 50% RH. The test piece was then pressed onto SUS by rolling it back and forth once with a 2 kg hand roller so that the adhesive area was 25 mm wide x 40 mm long. After leaving it in an atmosphere of 23°C and 50% RH for 24 hours, a 500 g load was applied and it was left in an 80°C environment for 10 hours. After 10 hours, the slippage of the test piece was evaluated using a microscope. [Evaluation Criteria] A: The test piece slippage was less than 0.1 mm: Excellent B: The test piece slippage was 0.1 mm or more but less than 0.4 mm: Good C: The test piece slippage was 0.4 mm or more but less than 10 mm: Usable D: The test piece slippage was 10 mm or more: Unusable

[0104] <Corrosion Resistance> After laminating the pressure-sensitive adhesive sheet onto aluminum foil, it was left under high-temperature and high-humidity conditions of 60°C x 90% RH for 48 hours. Thereafter, the pressure-sensitive adhesive sheet was peeled off from the aluminum foil, and the aluminum foil surface was visually inspected and evaluated according to the following criteria. [Evaluation Criteria] A: No discoloration was observed on the aluminum foil surface: Good B: Partial discoloration was observed on the aluminum foil surface: Usable C: Discoloration was observed on the aluminum foil surface: Unusable

[0105] <SUS Adhesion Strength> The 38 μm release liner was peeled off from the resulting pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer was bonded to a PET film substrate (Cosmoshine A-4360, 100 μm thick, manufactured by Toyobo Co., Ltd.), which was then cut into a size of 25 mm wide x 100 mm long to prepare a test pressure-sensitive adhesive sheet. The other 75 μm release liner was peeled off from this test pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer was attached to a SUS plate in an atmosphere of 23°C and 50% relative humidity (50% RH). Furthermore, the sheet was pressed with a roll in accordance with JIS Z-0237. After 24 hours of pressing, the peel strength (peel angle 180°, peel rate 300 mm / min; unit: N / 25 mm width) was measured using a tensile tester (Tensilon, manufactured by Orientec Co., Ltd.). [Evaluation Criteria] A: Peel strength of 3 N / 25 mm or more. : Usable. B: Peel strength less than 3 N / 25 mm. :Unusable

[0106]

[0107]

[0108]

[0109]

[0110] Although the present invention has been described with reference to the above-mentioned several embodiments, the present invention is not limited to these several embodiments. Various modifications can be made to the configuration and details of the present invention within the scope of the present invention.

[0111] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2024-033619 filed on March 6, 2024, and the subject matter described in Japanese Patent Application No. 2025-018597 filed on February 6, 2025, the entire disclosures of which are incorporated herein by reference.

[0112] 1 Pressure-sensitive adhesive layer, 2 Release film, 3 Substrate, 4 Device 1, 5 Device 2

Claims

1. A pressure-sensitive adhesive in which resin (A) is a copolymer of a monomer mixture, and the resin (A) contains, in 100% by mass of the monomer mixture, 30% by mass or more but less than 99.5% by mass of 2-octyl (meth)acrylate and 0.1% by mass or more but less than 40% by mass of a monomer having a hydroxy group, and the content of monomers having a carboxy group in 100% by mass of the monomer mixture is less than 0.5% by mass, and the content of other monomers other than 2-octyl (meth)acrylate, monomers having a hydroxy group, and monomers having a carboxy group is 55% by mass or less.

2. The adhesive according to claim 1, containing, per 100% by mass of the monomer mixture, 30% by mass or more but less than 90% by mass of 2-octyl (meth)acrylate and 10% by mass or more but less than 40% by mass of a monomer having a hydroxy group.

3. The adhesive according to claim 1, having a biomass content of 30% or more.

4. A pressure-sensitive adhesive composition comprising the pressure-sensitive adhesive according to claim 1 and a curing agent (B).

5. The pressure-sensitive adhesive composition according to claim 4, wherein the curing agent (B) comprises at least one of an isocyanate-based curing agent and an epoxy-based curing agent.

6. The pressure-sensitive adhesive composition according to claim 4, further comprising a silane coupling agent (C).

7. The pressure-sensitive adhesive composition according to claim 4, which has a gel fraction of 40% or more.

8. The pressure-sensitive adhesive composition according to claim 4, further comprising less than 50 parts by mass of a tackifier resin (D) per 100 parts by mass of the resin (A).

9. The pressure-sensitive adhesive composition according to claim 8, wherein the tackifier resin (D) has a biomass content of 80% or more.

10. A pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive according to any one of claims 1 to 3 or the pressure-sensitive adhesive composition according to any one of claims 4 to 9.

11. The pressure-sensitive adhesive layer according to claim 10, which has a dielectric constant of 0.5 or more at 20 GHz.

12. The pressure-sensitive adhesive layer according to claim 10, having an SUS adhesive strength of 3 N / 25 mm or more.

13. A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to claim 10 and a release film.

14. The pressure-sensitive adhesive sheet according to claim 13, wherein the release film has a thickness of less than 200 μm.

15. A laminate comprising the pressure-sensitive adhesive layer according to claim 10 and a substrate.

16. The laminate according to claim 15, wherein the thickness of the substrate is less than 500 μm.

17. A device with an adhesive layer comprising the adhesive layer according to claim 10 and a device.

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