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

Abstract

The present disclosure relates to an adhesive composition containing a curing agent and an adhesive containing an acrylic copolymer (A) which is a copolymer of a monomer mixture containing specific amounts of 2-octyl (meth)acrylate, an alkyl (meth)acrylate having an alkyl group with 1-4 carbon atoms, a monomer having a carboxy group, and a monomer having a cyclic structure.

Description

Adhesive composition, adhesive layer, adhesive sheet, laminate, and device with adhesive layer each using the same

[0001] The present disclosure relates to a pressure-sensitive adhesive composition, and a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, a laminate, and a device with a pressure-sensitive adhesive layer, all of which use the same.

[0002] Because adhesive sheets with adhesive layers formed from adhesives are easy to handle, they are used in a wide range of fields, from general-purpose applications such as labels and masking tape to medical and optical applications. Furthermore, adhesives have been used to bond components of various devices, including smartphones and televisions. Among these, adhesives used in applications where long-term use is expected, such as marking films, window films, automotive components, and optical displays, require durability, including heat resistance, moist heat resistance, and light resistance (yellowing resistance).

[0003] On the other hand, for convenient coating during the production 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 adjusted 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 Documents 1 and 2 are adjusted to a solid content of about 35%.

[0004] JP 2007-264092 A JP 2012-173354 A

[0005] The inventors of the present invention have found that when the solid content of the adhesives described in Patent Documents 1 and 2 is adjusted to 35% or more, the viscosity becomes too high, making coating difficult, and therefore it is not possible to increase the solid content. As a result, the high cost of the solvent used and the difficulty of applying a thick layer of adhesive have become major issues.

[0006] In addition to the increasing performance requirements, the depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products are becoming increasingly problematic in industries where pressure-sensitive adhesive sheets are used. Therefore, efforts are being made to conserve petroleum resources by replacing petroleum-derived materials with bio-derived materials 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 copolymers is to obtain an acrylic copolymer by copolymerizing a monomer mixture containing a (meth)acrylic acid alkyl ester monomer obtained by esterifying a linear alkyl alcohol produced by a living organism with (meth)acrylic acid. Increasing the proportion of environmentally friendly materials can contribute to further conserving petroleum resources, but this requires the use of limited environmentally friendly materials, making practical application difficult.

[0007] The problem to be solved by the present disclosure is to provide a pressure-sensitive adhesive composition that can contribute to the conservation of petroleum resources by increasing the proportion of environmentally friendly materials, which has heat resistance, moist heat resistance, and yellowing resistance, and has a low viscosity and is capable of high solidification, as well as a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, a laminate, and a device with a pressure-sensitive adhesive layer that use the same.

[0008] After extensive research, the present inventors discovered that the problems of the present invention can be solved in the following manner, leading to the completion of the present invention. Specifically, the present disclosure relates to a pressure-sensitive adhesive composition comprising an adhesive containing an acrylic copolymer (A) and a curing agent (B), wherein the adhesive comprises the acrylic copolymer (A), which is a copolymer of a monomer mixture containing 2-octyl(meth)acrylate (a1), an alkyl(meth)acrylate (a2) having 1 to 4 carbon atoms in the alkyl group, and a monomer (a3) ​​having a carboxy group, wherein the content of (a1) in 100% by mass of the monomer mixture is 45% by mass or more but less than 90% by mass, the content of (a2) in 100% by mass or more but less than 20% by mass, and the content of (a3) ​​in 100% by mass or more but less than 10% by mass. In this pressure-sensitive adhesive composition, the monomer mixture may also contain a monomer (a4) having a cyclic structure. Furthermore, in this pressure-sensitive adhesive composition, the content of (a4) in 100% by mass of the monomer mixture may be more than 0% by mass but less than 20% by mass.

[0009] The present disclosure makes it possible to provide a pressure-sensitive adhesive composition that can contribute to the conservation of petroleum resources, and that has heat resistance, moist heat resistance, and yellowing resistance, and is low in viscosity and capable of high solidification, as well as a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, a laminate, and a device with a pressure-sensitive adhesive layer that use the same.

[0010] Fig. 1 is a schematic cross-sectional view partially showing a laminate according to an example of the present disclosure; Fig. 2 is a schematic cross-sectional view partially showing a device with an adhesive layer according to an example of the present disclosure; Fig. 3 is a schematic cross-sectional view partially showing a pressure-sensitive adhesive sheet according to an example of the present disclosure.

[0011] 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

[15] .

[0012] [1] A pressure-sensitive adhesive composition comprising an adhesive containing an acrylic copolymer (A) and a curing agent (B), wherein the acrylic copolymer (A) is a copolymer of a monomer mixture containing 2-octyl(meth)acrylate (a1), an alkyl(meth)acrylate (a2) having 1 to 4 carbon atoms in the alkyl group, and a monomer (a3) ​​having a carboxy group, wherein the content of (a1) in 100% by mass of the monomer mixture is 45% by mass or more but less than 90% by mass, the content of (a2) in 100% by mass or more but less than 20% by mass, and the content of (a3) ​​in 100% by mass or more but less than 10% by mass. In [1], the monomer mixture may further contain a (meth)acrylic acid ester monomer (a4) having a cyclic structure. Furthermore, in [1], the content of (a4) in 100% by mass of the monomer mixture may be more than 0% by mass but less than 20% by mass. [2] The pressure-sensitive adhesive composition according to [1], wherein the curing agent (B) comprises at least one selected from the group consisting of epoxy-based curing agents, metal chelate-based curing agents, and aziridine-based curing agents. [3] The pressure-sensitive adhesive composition according to [1] or [2], further comprising a silane coupling agent (C). [4] The pressure-sensitive adhesive composition according to any one of [1] to [3], further comprising an acrylic copolymer (D) having a weight-average molecular weight of 50,000 or less, wherein the content of monomers having a homopolymer glass transition temperature of 90°C or higher is 80% by mass or more relative to 100% by mass of the total monomers constituting the acrylic copolymer (D). [5] The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the content of the acrylic copolymer (D) is less than 20 parts by mass per 100 parts by mass of the acrylic copolymer (A). [6] The pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the gel fraction is 60% or more. [7] The pressure-sensitive adhesive composition according to any one of [1] to [6], wherein the biomass content is 30% or more. [8] A pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition according to any one of [1] to [7]. [9] The pressure-sensitive adhesive layer according to [8], which has a haze of less than 2.0 after standing for 500 hours under conditions of 60°C and a relative humidity of 90%, and also has a haze of less than 2.0 after standing for 500 hours under conditions of 85°C and a relative humidity of 85%.

[10] The pressure-sensitive adhesive layer according to [8] or [9], characterized in that the Δb* value after standing for 500 hours in an 85°C atmosphere is 1.0 or less.

[11] A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to any one of [8] to

[10] and a release film.

[12] A laminate comprising the pressure-sensitive adhesive layer according to any one of [8] to

[10] and a substrate.

[13] A device with a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive layer according to any one of [8] to

[10] and a device.

[0013] Hereinafter, several embodiments of the present disclosure will be described, including pressure-sensitive adhesives and pressure-sensitive adhesive compositions, and pressure-sensitive adhesive layers, pressure-sensitive adhesive sheets, laminates, and devices with a pressure-sensitive adhesive layer using the same. However, the present invention is not limited thereto. In this specification, (meth)acrylate includes acrylate and methacrylate, and (meth)acryloxy group includes acryloxy group and methacryloxy group. A monomer is a monomer having an ethylenically unsaturated group. In this specification, numerical ranges specified using "to" include 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 materials, and "film" includes thick sheet-like materials. 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.

[0014] In this specification, "2-octyl (meth)acrylate (a1)" may be abbreviated as "monomer (a1)", "alkyl (meth)acrylate (a2) having an alkyl group with 1 to 4 carbon atoms" may be abbreviated as "monomer (a2)", "monomer (a3) ​​having a carboxy group" may be abbreviated as "monomer (a3)", and "(meth)acrylic acid ester monomer (a4) having a cyclic structure" may be abbreviated as "monomer (a4)".

[0015] <<Adhesive>> The adhesive of the present disclosure contains an acrylic copolymer (A).

[0016] <Acrylic Copolymer (A)> The acrylic copolymer (A) is a copolymer of a monomer mixture containing 2-octyl(meth)acrylate (a1), an alkyl(meth)acrylate (a2) having 1 to 4 carbon atoms in the alkyl group, and a monomer (a3) ​​having a carboxy group, and is characterized in that the content of monomer (a1) in 100% by mass of the monomer mixture is 45% by mass or more and less than 90% by mass, the content of monomer (a2) is 0.5% by mass or more and less than 20% by mass, and the content of monomer (a3) ​​is 0.5% by mass or more and less than 10% by mass.

[0017] [2-Octyl (meth)acrylate (a1)] 2-Octyl (meth)acrylate (a1) is a biomass monomer represented by the following formula (1): (Formula 1) (R1 = H, CH ３ ) The content of 2-octyl (meth)acrylate (a1) is 45% by mass or more and less than 90% by mass, based on 100% by mass of the monomer mixture. A content of 2-octyl (meth)acrylate (a1) less than 45% by mass is undesirable because it increases the viscosity of the PSA. The lower limit of the content of 2-octyl (meth)acrylate (a1) is 45% by mass or more, which can achieve the desired effect, but is preferably 55% by mass or more, and more preferably 65% ​​by mass or more. A higher content of 2-octyl (meth)acrylate (a1) is preferable because it contributes to the conservation of petroleum resources, but from the viewpoint of heat resistance, a preferred upper limit is less than 80% by mass, and more preferably less than 75% by mass. For example, the content of (a1) in 100% by mass of the monomer mixture may be 45% by mass or more and less than 90% by mass, 55% by mass or more and less than 80% by mass, 65% by mass or more and less than 75% by mass, or 70% by mass or more and less than 75% by mass.

[0018] [Alkyl (meth)acrylate (a2) having an alkyl group with 1 to 4 carbon atoms] The content of the alkyl (meth)acrylate (a2) having an alkyl group with 1 to 4 carbon atoms is 0.5% by mass or more and less than 20% by mass based on 100% by mass of the monomer mixture. A content of the alkyl (meth)acrylate (a2) having an alkyl group with 1 to 4 carbon atoms of 20% by mass or more is not preferred because it increases the viscosity of the adhesive. The lower limit of the content of the alkyl (meth)acrylate (a2) having an alkyl group with 1 to 4 carbon atoms is 0.5% by mass or more to achieve the desired effect, but is preferably 5% by mass or more, and more preferably 8% by mass or more. The above range is preferred because it can impart cohesive strength to the adhesive layer and improve heat resistance, but from the viewpoint of viscosity, it is preferably less than 18% by mass, and even more preferably less than 16% by mass. For example, the content of (a2) in 100% by mass of the monomer mixture may be 0.5% by mass or more and less than 20% by mass, 1% by mass or more and less than 19% by mass, 5% by mass or more and less than 18% by mass, 8% by mass or more and less than 16% by mass, or 8% by mass or more and less than 12% by mass.

[0019] [Monomer (a3) ​​Having a Carboxy Group] The monomer (a3) ​​having a carboxy group is not limited as long as it is a monomer having a carboxy group in the molecule, and specific examples thereof include (meth)acrylic acid, p-carboxybenzyl acrylate, β-carboxyethyl acrylate, maleic acid, monoethyl maleate, itaconic acid, citraconic acid, and fumaric acid.

[0020] The content of the carboxyl group-containing monomer (a3) ​​is 0.5% by mass or more and less than 10% by mass based on 100% by mass of the monomer mixture. It is preferably 2% by mass or more and less than 8% by mass, more preferably 3% by mass or more and less than 6% by mass, and even more preferably 3% by mass or more and less than 5% by mass. By using a carboxyl group-containing monomer (a3) ​​of 0.5% by mass or more, curing can be promoted, whitening under wet heat can be suppressed, and the cohesive strength of the adhesive layer can be increased, thereby imparting heat resistance. Furthermore, by using a carboxyl group-containing monomer (a3) ​​of less than 10% by mass, an increase in the viscosity of the solution can be suppressed.

[0021] [Monomer (a4) Having a Cyclic Structure] The monomer mixture constituting the acrylic copolymer (A) may further contain a monomer (a4) having a cyclic structure. Examples of the monomer (a4) having a cyclic structure include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate. When the monomer (a4) having a cyclic structure is contained, its content is preferably greater than 0% by mass and less than 20% by mass, and may be 0.1% by mass or more and less than 19% by mass, 0.5% by mass or more and less than 18% by mass, 1% by mass or more and less than 16% by mass, or 2% by mass or more and less than 15% by mass, based on 100% by mass of the monomer mixture. Furthermore, its content is more preferably 5% by mass or more and less than 12.5% ​​by mass, and even more preferably 8% by mass or more and less than 12% by mass. By keeping the content within the above ranges, heat resistance, moist heat resistance, and suppression of increase in solution viscosity can be achieved. In consideration of the environment, it is preferable to use isobornyl (meth)acrylate, which is a biomass monomer. From the viewpoint of reactivity, it is preferable to use a (meth)acrylate having a cyclic structure. Furthermore, the amount of the monomer (a4) having a cyclic structure per 100 parts by mass of 2-octyl (meth)acrylate (a1) may be 0.5 to 40 parts by mass, 1 to 30 parts by mass, or 5 to 20 parts by mass.

[0022] [Other Monomers] The other monomers are not particularly limited as long as they are monomers other than 2-octyl(meth)acrylate (a1), alkyl(meth)acrylate (a2) having an alkyl group with 1 to 4 carbon atoms, monomers (a3) ​​having a carboxy group, and monomers (a4) having a cyclic structure. In consideration of the environment, it is preferable to use a (meth)acrylate, which is a biomass monomer, as the other monomer, and it is more preferable to use a (meth)acrylate with a high biomass content.

[0023] Examples of other monomers include acrylamide, N,N-dimethylacrylamide, methacrylonitrile, acrylonitrile, diacetone acrylamide, stearyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, etc. Stearyl (meth)acrylate and lauryl (meth)acrylate, which are biomass monomers, are preferred.

[0024] The other monomer may or may not be contained, but if contained, the content is less than 50% by mass relative to 100% by mass of the monomer mixture. By setting the content to less than 50% by mass, it is possible to suppress an increase in viscosity of the PSA. From the viewpoint of suppressing an increase in viscosity, the content is preferably 40% by mass or less, more preferably 20% by mass or less.

[0025] (Production of Acrylic Copolymer (A)) The acrylic copolymer (A) can be produced by polymerizing the monomer mixture. Although known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization are possible for the polymerization, 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.

[0026] 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; Examples of the peroxyketals include 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 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.

[0027] 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).

[0028] 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.

[0029] (Weight-average molecular weight (Mw)) The Mw of the acrylic copolymer (A) is not particularly limited, but is preferably 1.8 million or less, and more preferably 1 million or less. The Mw is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0030] <<Pressure-Sensitive Adhesive Composition>> The pressure-sensitive adhesive composition of the present disclosure contains a pressure-sensitive adhesive containing an acrylic copolymer (A) and a curing agent (B). It may also contain a silane coupling agent (C) and an acrylic copolymer (D) having a weight-average molecular weight of 50,000 or less, as needed.

[0031] <Curing Agent (B)> The pressure-sensitive adhesive composition contains a curing agent (B), and the curing agent (B) can be any agent that provides 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 selected from the group consisting of epoxy curing agents, metal chelate curing agents, and aziridine curing agents. The inclusion of at least one curing agent is preferred in that it can moderately increase the cohesive strength of the pressure-sensitive adhesive and is less likely to adversely affect other physical properties.

[0032] 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.

[0033] Examples of metal chelate curing agents include aluminum organic compounds, zirconium compounds, etc. Specific examples of commercially available products include Aluminum Chelate D and Aluminum Chelate A (both manufactured by Kawaken Fine Chemical Co., Ltd.), and ZC-750 (manufactured by Matsumoto Fine Chemical Co., Ltd.).

[0034] Examples of the aziridine-based curing agent include 1,1,1-propanetriyltrismethylene tris(1-aziridinepropionic acid), 2-[[[3-(2-methylaziridin-1-yl)propionyl]oxy]methyl]-2-ethylpropane-1,3-diol bis[3-(2-methylaziridin-1-yl)propionate], and the like.

[0035] 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 acrylic copolymer (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 and heat resistance.

[0036] <Silane Coupling Agent (C)> The pressure-sensitive adhesive composition preferably contains a silane coupling agent (C). By containing the silane coupling agent (C), it is possible to improve adhesive strength, heat resistance, and resistance to moist heat whitening. The silane coupling agent (C) is preferably contained in an amount of 0.05 to 0.2 parts by mass per 100 parts by mass of the acrylic copolymer (A). By using an amount of 0.05 to 0.2 parts by mass, it becomes easy to achieve both heat resistance and resistance to moist heat whitening.

[0037] 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), and KBM-303 (2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane) (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0038] <Acrylic Copolymer (D) Having a Weight-Average Molecular Weight of 50,000 or Less> From the viewpoint of heat resistance, the pressure-sensitive adhesive composition preferably further contains an acrylic copolymer (D). The acrylic copolymer (D) has a weight-average molecular weight (Mw) of 50,000 or less, and is characterized in that, based on a total of 100% by mass of the monomer mixture constituting the acrylic copolymer (D), a content of monomers having a homopolymer glass transition temperature of 90°C or higher (hereinafter also referred to as high Tg monomers) is 80% by mass or more. When the Mw of the acrylic copolymer (D) is 50,000 or less, it is compatible with the acrylic copolymer (A), and heat resistance can be improved while suppressing an increase in haze. The Mw of the acrylic copolymer (D) is preferably 30,000 or less. However, the acrylic copolymer (D) is a copolymer other than the acrylic copolymer (A). When the acrylic copolymer (D) contains 80% by mass or more of the high Tg monomer, cohesion is imparted to the adhesive layer, improving heat resistance. The content of the high Tg monomer in the total 100% by mass of the monomer mixture may be 100% by mass, but is preferably 99.5% by mass or less.

[0039] Examples of monomers having a homopolymer glass transition temperature of 90° C. or higher include isobornyl (meth)acrylate, methyl methacrylate, acryloylmorpholine, N,N-dimethylacrylamide, etc. From the viewpoint of saving petroleum resources, it is preferable to use isobornyl (meth)acrylate, which is a biomass monomer.

[0040] As the monomer other than isobornyl (meth)acrylate constituting the acrylic copolymer (D), the various monomers described in the description of the acrylic copolymer (A) can be used.

[0041] The acrylic copolymer (D) can be produced by polymerizing a monomer mixture in the same manner as the acrylic copolymer (A). Although known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization are possible, solution polymerization is preferred. Examples of solvents used in solution polymerization include 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. A chain transfer agent can also be added as needed.

[0042] The amount of the acrylic copolymer (D) is preferably less than 20 parts by mass per 100 parts by mass of the acrylic copolymer (A). By using less than 20 parts by mass, it is possible to impart an appropriate cohesive force to the adhesive layer and improve heat resistance.

[0043] 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.

[0044] Examples of chlorinated polyolefins include chlorinated polypropylene, acid-modified chlorinated polypropylene, acrylic-modified chlorinated polypropylene, chlorinated polyethylene, chlorinated ethylene vinyl acetate copolymer, etc., and chlorinated polypropylene or chlorinated ethylene vinyl acetate copolymer is preferred from the viewpoint of good compatibility with acrylic copolymers, etc. 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.).

[0045] The pressure-sensitive adhesive composition of the present disclosure preferably has a gel fraction of 60% or more. However, depending on the application, a gel fraction of 60% or less may also be used. The method for measuring the gel fraction will be described in detail in the Examples.

[0046] The pressure-sensitive adhesive composition of the present disclosure contains an acrylic copolymer (A), which is a copolymer of a monomer mixture containing a specific monomer, thereby suppressing the increase in viscosity when using the acrylic copolymer and ensuring heat resistance and moist heat resistance. This allows for a significant reduction in the amount of organic solvent used to adjust the viscosity during application compared to conventional methods. The Mw of the acrylic copolymer (A) can be adjusted as needed, but in the present disclosure, when the Mw of the acrylic copolymer (A) is 600,000 to 1,000,000, the viscosity at a solids content of 35% (±1%) is preferably 6,000 mPa·s or less. The method for preparing the solids content and the method for measuring the viscosity are described in detail in the Examples.

[0047] <<Pressure-Sensitive Adhesive Layer>> The pressure-sensitive adhesive layer is a layer obtained from 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.

[0048] The pressure-sensitive adhesive layer of the present disclosure preferably has durability such as heat resistance and moist heat resistance so that it can be used for long periods of time in optical displays, etc. In terms of heat resistance and moist heat resistance, it is preferable that the haze after leaving the layer at 60°C and 90% relative humidity for 500 hours is less than 2.0, the haze after leaving the layer at 85°C and 85% relative humidity for 500 hours is less than 2.0, and the Δb* value after leaving the layer at 85°C for 500 hours is 1.0 or less, and that no foaming or lifting due to the pressure-sensitive adhesive layer occurs under the above conditions. The measurement method is described in detail in the Examples.

[0049] <<Adhesive Sheet>> The adhesive sheet comprises an adhesive layer made of the adhesive or adhesive composition of the present disclosure and a release film.

[0050] 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.

[0051] <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.

[0052] As the release film, among the above-mentioned transparent plastic substrates, 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.

[0053] 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.

[0054] The pressure-sensitive adhesive sheet of the present disclosure has excellent heat resistance and moist heat resistance, and can therefore be used for fixing the exterior or interior of various devices such as personal computers, mobile phones, home appliances, etc. Furthermore, it can be used to fix materials different from the device, such as, but not limited to, 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.

[0055] 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, heptane, etc.; ester solvents such as ethyl acetate, butyl acetate, etc.; ketone solvents such as acetone, methyl ethyl ketone, etc.; halogenated hydrocarbon solvents such as dichloromethane, chloroform, etc.; ether solvents such as diethyl ether, methoxytoluene, dioxane, etc., or other hydrocarbon solvents.However, water and alcohols should be used carefully because they may cause the reaction between the acrylic copolymer (A) and the isocyanate curing agent to be inhibited.

[0056] 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.

[0057] The thickness of the adhesive layer is preferably 2 to 1,000 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.

[0058] <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.

[0059] <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.

[0060] A schematic cross-sectional view partially illustrating an example of a laminate according to the present disclosure is shown in Fig. 1. In Fig. 1, 3 is a substrate, 1 is a pressure-sensitive adhesive layer, and 4 and 5 are devices.

[0061] In the laminate shown in FIG. 1, the substrate is attached to the device via an adhesive layer.

[0062] <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.

[0063] <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.

[0064] Figure 2 shows a schematic cross-sectional view partially illustrating a device with a pressure-sensitive adhesive layer, which is an example of use of a pressure-sensitive adhesive sheet according to one example of the present disclosure. In Figure 2, 3 is a substrate, 1 is a 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.

[0065] In the device with a pressure-sensitive adhesive layer shown in Fig. 3, the substrate is attached to a release film via a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) according to an example of the present disclosure. In this way, the device can be manufactured with the release film provided, or can be used in an intermediate process of manufacturing the product.

[0066] There are no particular limitations on the uses of devices with adhesive layers, but examples include all kinds of home appliances such as personal computers, mobile phones, televisions, tablets, and smart watches.

[0067] In view 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 biomass monomers as the monomers constituting the acrylic copolymer (A) and the acrylic copolymer (D). 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.

[0068] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, unless otherwise specified, "parts" and "%" refer to "parts by mass" and "% by mass," respectively. The 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 that no component is added. It is common technical knowledge that the viscosity of a pressure-sensitive adhesive composition varies depending on the Mw of the acrylic copolymer (A) contained therein. Since the Mw of the acrylic copolymer (A) can be adjusted appropriately, it is not practical to confirm the effects of the present invention over the entire Mw range of the acrylic copolymer (A). Therefore, the acrylic copolymer (A) described in the examples was produced and evaluated so that its Mw was between 600,000 and 1,000,000.

[0069] <Measurement of weight-average molecular weight (Mw) and Mw classification evaluation method> 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". The column used was a TSKgel α-M manufactured by Tosoh Corporation, two of which were connected in series. N,N-dimethylformamide (DMF) was used as the eluent, and measurements were performed at 40°C. The Mw was determined by conversion using polystyrene with a known Mw as the standard substance.

[0070] (Production of Acrylic Copolymer) Example 1: Production of (A-1) Using a reaction apparatus equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, ethyl acetate was added as a polymerization solvent to a reaction vessel, and 85 parts of 2-octyl acrylate (2-OA) as monomer (a1), 10 parts of methyl acrylate (MA) as monomer (a2), and 5 parts of acrylic acid (AA) as monomer (a3) ​​were added and stirred to prepare a monomer mixture. 0.02 parts of azobisisobutyronitrile (hereinafter, AIBN) was added as an initiator and mixed, followed by polymerization 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 an acrylic copolymer solution. The resulting acrylic copolymer was designated (A-1).

[0071] <Production of Examples 2 to 32, Example 76 (A-2 to A-32, A-33), and Examples c1 to c6 (A'-1 to A'-6)> Acrylic copolymers (A-2 to A-32, A-33, A'-1 to A'-6) were produced in the same manner as in the production of the acrylic copolymer (Example 1), except that the compositions and blending amounts (parts by mass) were changed to those shown in Tables 1 to 3.

[0072]

[0073]

[0074]

[0075] The abbreviations in Tables 1 to 3 are as follows. Note that only confirmed biomass levels are listed. [2-Octyl (meth)acrylate (a1)] 2-OA: 2-octyl acrylate (biomass degree 73%) 2-OMA: 2-octyl methacrylate (biomass degree 67%) [Alkyl (meth)acrylate (a2) having 1 to 4 carbon atoms in the alkyl group] MA: methyl acrylate (alkyl group has 1 carbon atom) MMA: methyl methacrylate (alkyl group has 1 carbon atom) TBA: t-butyl acrylate (alkyl group has 4 carbon atoms) [Monomer (a3) ​​having a carboxy group] AA: acrylic acid MAA: methacrylic acid [Monomer (a4) having a cyclic structure] IBXA: isobornyl acrylate (biomass degree 76%) IBXMA: isobornyl methacrylate (biomass degree 71%) BZA: benzyl acrylate [Other monomers] 2EHA: 2-ethylhexyl acrylate LA: lauryl acrylate (biomass degree 80%)

[0076] <Production Example 1: Production of (D-1)> Using a reaction apparatus equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping tube, 100 parts of toluene as a polymerization solvent was charged into a reaction vessel, and a mixture of 100 parts of isobornyl methacrylate, 15 parts of methyl ethyl ketone as a polymerization solvent, and 2 parts of AIBN as an initiator was added dropwise to the dropping vessel over approximately 2 hours, and polymerization was carried out for 6 hours at approximately 90°C under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate, and the resulting acrylic copolymer was designated D-1. The weight average molecular weight (Mw) of the resulting acrylic copolymer was measured, and the results are shown in Table 4.

[0077] <Production of Production Examples 2 and 3> Acrylic copolymers (D-2) and (D'-1) were produced in the same manner as in Production Example 1, except that the compositions and blending amounts (parts by mass) were changed to those shown in Table 4.

[0078]

[0079] The abbreviations in Table 4 are as follows: [Monomers with a homopolymer Tg of 90°C or higher] IBXA: isobornyl acrylate (Tg: 97°C) IBXMA: isobornyl methacrylate (Tg: 180°C) DMAA: N,N-dimethylacrylamide (Tg: 119°C) [Other monomers] CHA: cyclohexyl acrylate (Tg: 15°C) 2EHA: 2-ethylhexyl acrylate (Tg: -70°C)

[0080] Example 33 A pressure-sensitive adhesive composition was obtained by blending 0.05 parts of "Tetrad-X" (an epoxy-based curing agent manufactured by Mitsubishi Gas Chemical Company, Inc.) as the curing agent (B) with 100 parts of the acrylic copolymer (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 Tocello Inc.) as a release sheet so that the dried thickness 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 Tocello Inc.) as a release sheet was laminated to the pressure-sensitive adhesive layer and aged in this state at 23°C for 7 days to obtain a pressure-sensitive adhesive sheet.

[0081] <Examples 34 to 75, 77, c7 to c12> As shown in Table 5, pressure-sensitive adhesive compositions and pressure-sensitive adhesive sheets were obtained in the same manner as in Example 33, except that the types and blending amounts of the acrylic copolymer (A), curing agent (B), silane coupling agent (C), and acrylic copolymer (D) were changed.

[0082] <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), which was then cut into a size of 30 mm wide x 100 mm long to prepare a test pressure-sensitive adhesive sheet. A 75 μm release liner was then peeled off from the other side of the pressure-sensitive adhesive sheet to prepare a test specimen, whose 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 Table 5, "60%<" means that the gel fraction is greater than 60%. 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)

[0083] <Calculation of Biomass Degree> The biomass degree of the PSA composition was calculated using the following formula (2): (In the case of a two-component (A, B) monomer system) Biomass degree = {(Aw x Ab) + (Bw x Bb)} / (Aw + Bw) (2) Aw: weight of monomer A, Bw: weight of monomer B Ab: biomass degree (%) of monomer A, Bb: biomass degree (%) of monomer B When the biomass degree was specified as a range, the minimum value was used for the calculation.

[0084] The materials used in each example are listed below. <Curing agent (B)> Tetrad X: Epoxy-based curing agent manufactured by Mitsubishi Gas Chemical Company, Inc. Aluminum Chelate A: Metal chelate-based curing agent manufactured by Kawaken Fine Chemicals Co., Ltd. PZ-33: Aziridine-based curing agent manufactured by Nippon Shokubai Co., Ltd.

[0085] <Silane Coupling Agent (C)> KBE-403: (3-glycidoxypropyltriethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0086] The adhesives and adhesive compositions obtained in Examples 33 to 75, 77, and c7 to c12 were evaluated for low viscosity, heat resistance, resistance to wet heat whitening, and resistance to yellowing by the following methods. The results are shown in Table 6.

[0087] <Low Viscosity> The viscosity of the pressure-sensitive adhesives and pressure-sensitive adhesive compositions of Examples 33 to 75, 77, and c7 to c12 was measured by the following method, and low viscosity was evaluated according to the following evaluation criteria. The solid content of the contained acrylic copolymer was adjusted to 35% (±1), and the viscosity was measured using a Brookfield viscometer (rotor number: M3, rotation speed: 12 rpm). The solid content was adjusted using ethyl acetate. [Evaluation Criteria] A: Viscosity less than 3,000 mPas·s: Excellent B: Viscosity 3,000 mPas·s or more but less than 4,000 mPas·s: Good C: Viscosity 4,000 mPas·s or more but less than 5,000 mPas·s: Usable D: Viscosity 5,000 mPas·s or more: Unusable

[0088] <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% relative humidity (also referred to as 23°C-50% RH). The test piece was then pressed onto SUS by rolling a 2 kg hand roller back and forth once so that the applied area was 25 mm wide x 40 mm long. After leaving the test piece in an atmosphere of 23°C-50% RH for 24 hours, a 500 g load was applied and the test piece was left to stand in an 80°C environment for 10 hours. After 10 hours, the test piece was evaluated for displacement using a microscope. S: No deviation of the test piece: Best A: Deviation of the test piece is more than 0 mm and less than 0.1 mm: Excellent B: Deviation of the test piece is 0.1 mm or more and less than 0.4 mm: Good C: Deviation of the test piece is 0.4 mm or more and less than 1.0 mm: Usable D: Deviation of the test piece is 1.0 mm or more: Unusable

[0089] <Heat and Humidity Whitening> The 38 μm release liner was peeled off from the obtained pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer was bonded to a glass plate using a laminator in an atmosphere of 23°C and 50% RH. Next, the other 75 μm release liner was peeled off from the pressure-sensitive adhesive sheet, and the sheet was bonded to a glass plate using a laminator in the same manner as above. This was held for 20 minutes under a pressure of 0.5 MPa in an atmosphere of 50°C to prepare a test specimen laminated in the order glass plate / pressure-sensitive adhesive layer / glass plate, and these were then left for 500 hours in environments of 60°C and 90% relative humidity (also referred to as 60°C-90% RH) and 85°C and 85% relative humidity (also referred to as 85°C-85% RH). Each was cooled for 1 hour at 23°C and 50% RH to obtain a test specimen. The haze of each test specimen was measured and evaluated according to the following criteria. The haze was measured using a Turbidimeter NDH5000W manufactured by Nippon Denshoku Industries Co., Ltd. [Evaluation criteria] A: haze less than 0.5. Excellent B: haze 0.5 or more and less than 1.0. Good C: haze 1.0 or more and less than 2.0. Fairly good D: haze 2.0 or more. Unusable

[0090] <Yellowing Resistance> The 38 μm release liner was peeled off from the obtained pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer was laminated to a glass plate using a laminator in an atmosphere of 23°C and 50% RH. Next, the other 75 μm release liner was peeled off from the pressure-sensitive adhesive sheet, and the sheet was laminated to a glass plate using a laminator in the same manner as above. This was held for 20 minutes under a pressure of 0.5 MPa in an atmosphere of 50°C to prepare a test piece laminated in the order glass plate / pressure-sensitive adhesive layer / glass plate, and then left in an environment of 85°C for 500 hours. After cooling at 23°C and 50% RH for 1 hour, the b* value was measured, and the Δb* value was calculated using the following formula. The b* value was measured using an SE6000 manufactured by Nippon Denshoku Industries Co., Ltd. Δb* value = [b* value after leaving for 500 hours] - [b* value before test] [Evaluation Criteria] A: Δb* value is 1.0 or less. : Good. D: Δb* value is greater than 1.0. Unusable

[0091]

[0092]

[0093] 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.

[0094] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2024-099655, filed on June 20, 2024, the entire disclosure of which is incorporated herein by reference.

[0095] 1 Pressure-sensitive adhesive layer, 2 Release film, 3 Substrate, 4 Device 1, 5 Device 2

Claims

1. A pressure-sensitive adhesive composition comprising an acrylic copolymer (A) and a curing agent (B), wherein the acrylic copolymer (A) is a copolymer of a monomer mixture containing 2-octyl(meth)acrylate (a1), an alkyl(meth)acrylate (a2) having 1 to 4 carbon atoms in the alkyl group, a monomer (a3) ​​having a carboxy group, and a monomer (a4) having a cyclic structure, wherein the content of (a1) in 100% by mass of the monomer mixture is 45% by mass or more but less than 90% by mass, the content of (a2) is 0.5% by mass or more but less than 20% by mass, the content of (a3) ​​is 0.5% by mass or more but less than 10% by mass, and the content of (a4) is more than 0% by mass but less than 20% by mass.

2. The pressure-sensitive adhesive composition according to claim 1, wherein the curing agent (B) comprises at least one member selected from the group consisting of epoxy-based curing agents, metal chelate-based curing agents, and aziridine-based curing agents.

3. The pressure-sensitive adhesive composition according to claim 1, further comprising a silane coupling agent (C).

4. The pressure-sensitive adhesive composition according to claim 1, further comprising an acrylic copolymer (D) having a weight-average molecular weight of 50,000 or less, wherein the content of monomers having a homopolymer glass transition temperature of 90°C or higher is 80% by mass or more out of a total of 100% by mass of the monomer mixture constituting the acrylic copolymer (D).

5. The pressure-sensitive adhesive composition according to claim 4, wherein the content of the acrylic copolymer (D) is less than 20 parts by mass per 100 parts by mass of the acrylic copolymer (A).

6. The pressure-sensitive adhesive composition according to claim 1, which has a gel fraction of 60% or more.

7. The pressure-sensitive adhesive composition according to claim 1, having a biomass content of 30% or more.

8. A pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition according to any one of claims 1 to 7.

9. The pressure-sensitive adhesive layer according to claim 8, which has a haze of less than 2.0 after standing for 500 hours under conditions of 60°C and 90% relative humidity, and a haze of less than 2.0 after standing for 500 hours under conditions of 85°C and 85% relative humidity.

10. The pressure-sensitive adhesive layer according to claim 8, which has a Δb* value of 1.0 or less after being left standing in an 85° C. atmosphere for 500 hours.

11. A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to claim 8 and a release film.

12. A laminate comprising the pressure-sensitive adhesive layer according to claim 8 and a substrate.

13. A device with an adhesive layer, comprising the adhesive layer according to claim 8 and a device.

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