Adhesive, Adhesive Sheet, Laminate

Abstract

An adhesive comprising an acrylic polymer (A) which is a copolymer of a monomer mixture, a rosin-based tackifier resin (B1) having a softening point of 120° C. or higher, and a curing agent (C), wherein the content of the rosin-based tackifier resin (B1) relative to 100 parts by mass of the acrylic polymer (A) is 10 parts by mass or more and less than 60 parts by mass, and in 100% by mass of the monomer mixture, monomer (a1) is 30% by mass or more and less than 95% by mass, monomer (a2) is 1% by mass or more and less than 10% by mass, and monomer (a3) is 4% by mass or more and 69% by mass or less, and further, the adhesive may contain less than 0.7% by mass of monomer (a4). Here, (a1) is 2-octyl (meth)acrylate, (a2) is a monomer having a carboxy group, (a3) is other monomers other than monomer (a1), monomer (a2), and monomer (a4), and (a4) is a monomer having a hydroxy group.

Description

[Technical Field]

[0001] The present disclosure relates to a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and a laminate. [Background technology]

[0002] Due to their ease of handling, adhesive sheets with adhesive layers formed from adhesives are widely used in a wide range of applications, including labeling and medical applications. They are also widely used in various optical displays, such as liquid crystal displays (LCDs) and organic electroluminescence displays (OLEDs). Optical displays are also used as input devices, such as touch panels, in addition to display devices. Touch panels are often equipped with cover panels to protect their surfaces. The components that make up these optical displays are typically bonded together via an adhesive layer. Adhesives used in applications expected to be used for long periods, such as marking films, window films, automotive components, and optical displays, require high adhesion to the substrate to prevent peeling during use. For automotive and label applications, adhesive sheets must adhere to not only metal but also plastic materials. Therefore, they must be durable (constant-load peel resistance) to prevent poor appearance, such as lifting or peeling, at the adhesive interface with the adhesive layer, even under conditions of continuous load due to material expansion or its own weight.

[0003] In addition to the above-mentioned increasing performance requirements, the depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products are becoming issues in the industries in which PSA sheets are used. Therefore, attempts are being made to conserve petroleum resources by using bio-derived materials instead of petroleum-derived materials in various industries, starting with the packaging materials field, but also in the optical and semiconductor fields. One method for increasing the proportion of biologically derived materials in adhesives whose main component is an acrylic polymer 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. There are also products made from natural-derived components for the adhesion-imparting resin, and by selectively using this, it is possible to achieve environmentally friendly productization.

[0004] The adhesives described in Patent Document 1, Patent Document 2, and Patent Document 3 use acrylic polymers made from bio-derived materials. When the inventors examined them, the adhesives described in these documents cannot achieve both adhesive strength, peel resistance under a constant load, tackiness, etc., which has become a major issue.

[0005] Also, by increasing the ratio of environmentally friendly materials, it is possible to contribute more to the conservation of petroleum resources. However, at present, there are problems with the fixability of the originally obtained performance, such as adhesive strength, peel resistance under a constant load, tackiness, etc., due to the use of limited environmentally friendly materials.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem to be solved by the present invention is an adhesive that can contribute more to the conservation of petroleum resources by increasing the ratio of environmentally friendly materials, and also has high adhesive strength performance with respect to the adherend and can achieve both peel resistance under a constant load and tackiness, and to provide an adhesive sheet and a laminate using the same.

Means for Solving the Problems

[0008] As a result of intensive studies by the present inventors, it has been found that the problems of the present invention can be solved in the following aspects, and the present invention has been completed. That is, the present disclosure provides an adhesive comprising an acrylic polymer (A) which is a copolymer of a monomer mixture, a rosin tackifier resin (B1) having a softening point of 120 degrees or more, and a curing agent (C), wherein the content of the rosin tackifier resin (B1) with respect to 100 parts by mass of the acrylic polymer (A) is 10 parts by mass or more and less than 60 parts by mass, and in 100% by mass of the monomer mixture, the following monomer (a1) is contained in an amount of 30% by mass or more and less than 95% by mass, the following monomer (a2) is contained in an amount of 1% by mass or more and less than 10% by mass, and the following monomer (a3) is contained in an amount of 4% by mass or more and 69% by mass or less, and further, the following monomer (a4) may be contained in an amount of less than 0.7% by mass. (a1) 2-octyl (meth) acrylate (a2) A monomer having a carboxy group (a3) Other monomers other than monomer (a1), monomer (a2), and monomer (a4) (a4) A monomer having a hydroxy group

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide an adhesive that can contribute to the conservation of petroleum resources, an adhesive that has high adhesive performance to an adherend and can achieve both constant load peel resistance and tack, an adhesive sheet using the same, and a laminate.

Brief Description of the Drawings

[0010] [Figure 1] It is a schematic cross-sectional view showing an example of the laminate of the present disclosure partially. [Diagram 2] It is a schematic diagram when testing the constant load peel resistance of the adhesive sheet.

Modes for Carrying Out the Invention

[0011] The adhesive, adhesive sheet, and laminate according to the present disclosure have the following configurations [1] to

[17] .

[0012] [1] An adhesive comprising an acrylic polymer (A) which is a copolymer of a monomer mixture, a rosin tackifier resin (B1) having a softening point of 120 degrees or higher, and a curing agent (C), wherein the content of the rosin tackifier resin (B1) with respect to 100 parts by mass of the acrylic polymer (A) is 10 parts by mass or more and less than 60 parts by mass, in 100% by mass of the monomer mixture, the following monomer (a1) is 30% by mass or more and less than 95% by mass, the following monomer (a2) is 1% by mass or more and less than 10% by mass, the following monomer (a3) is 4% by mass or more and 69% by mass or less, and contains an adhesive. Further, the adhesive may contain less than 0.7% by mass of the following monomer (a4). (a1) 2-octyl (meth) acrylate (a2) A monomer having a carboxy group (a3) Other monomers other than monomer (a1), monomer (a2), and monomer (a4) (a4) A monomer having a hydroxy group [2] The adhesive according to [1] above, wherein monomer (a3) contains a monomer (a3-1) (excluding monomer (a2) and monomer (a4)) having a glass transition temperature of 0 ° C or higher of the homopolymer. [3] The adhesive according to [1] or [2] above, wherein monomer (a3) contains an alkyl (meth) acrylate monomer (a3-2) (excluding monomer (a2) and monomer (a4)) having 2 to 8 carbon atoms in the alkyl group and a glass transition temperature of less than 0 ° C of the homopolymer. [4] The adhesive according to any one of [1] to [3] above, which contains 0.03% by mass or more and less than 0.7% by mass of monomer (a4) in 100% by mass of the monomer mixture. [5] The adhesive according to any one of [1] to [4] above, having a biomass content of 30% or more. [6] The adhesive according to any one of [1] to [5] above, wherein the biomass content of the rosin tackifier resin (B1) is 80% or more. [7] The pressure-sensitive adhesive according to any one of [1] to [6] above, wherein the hydroxyl value of the rosin-based tackifier resin (B1) is 20 mgKOH / g or more. [8] Further, it contains 10 parts by mass or more and less than 60 parts by mass of a tackifier resin (B2) having a softening point of 90 degrees or more and less than 120 degrees with respect to 100 parts by mass of the acrylic polymer (A), The pressure-sensitive adhesive according to any one of [1] to [7] above, wherein the tackifier resin (B2) contains at least one selected from the group consisting of a rosin-based tackifier resin, an aliphatic petroleum resin, an aromatic petroleum resin, an aliphatic / aromatic petroleum resin, and a terpene-based tackifier. [9] The pressure-sensitive adhesive according to any one of [1] to [8] above, wherein the curing agent (C) contains at least one selected from the group consisting of an isocyanate-based curing agent, an epoxy-based curing agent, and an aluminum chelate-based curing agent.

[10] The pressure-sensitive adhesive according to any one of [1] to [9] above, wherein the gel fraction is less than 50%.

[11] A pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive according to any one of [1] to

[10] above.

[12] The pressure-sensitive adhesive layer according to

[11] above, wherein the SUS adhesive strength is 10 N / 25 mm or more.

[13] The pressure-sensitive adhesive layer according to

[11] or

[12] above, wherein the PE adhesive strength is 5 N / 25 mm or more.

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

[11] to

[13] above and a release film.

[15] The pressure-sensitive adhesive sheet according to

[14] above, wherein the thickness of the release film is less than 200 μm.

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

[11] to

[13] above and a substrate.

[17] The basis weight of the substrate is 230 g / m 2 The laminate according to

[16] above, which is less than.

[0013] Hereinafter, the compositions, pressure-sensitive adhesive sheets, and laminates of the present disclosure will be described, but are 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 addition, in this specification, a numerical range specified using "to" includes the numerical values before and after "to" as the range of the lower and upper limits. Furthermore, "film" and "sheet" are not distinguished by thickness. In other words, in this specification, "sheet" includes thin film-like products, and "film" includes thick sheet-like products. Furthermore, the term "adherend" refers to a counterpart to which the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is attached. Unless otherwise noted, the various components appearing in this specification may be used independently either alone or in combination of two or more.

[0014] <Adhesive> The pressure-sensitive adhesive of the present disclosure comprises an acrylic polymer (A), a rosin-based tackifying resin (B1) having a softening point of 120° C. or higher, and a curing agent (C).

[0015] <Acrylic polymer (A)> The acrylic polymer (A) is a copolymer of a monomer mixture, and the monomer mixture contains, in 100% by mass, 30% by mass or more and less than 95% by mass of the following monomer (a1), The following monomer (a2) is contained in an amount of 1% by mass or more and less than 10% by mass: The copolymer contains the following monomer (a3) in an amount of 4% by mass or more and 69% by mass or less: Furthermore, the pressure-sensitive adhesive may contain less than 0.7 mass % of the following monomer (a4). (a1) 2-octyl (meth)acrylate (a2) Monomer having a carboxy group (a3) Other monomers other than the monomers (a1), (a2), and (a4). (a4) Monomer having a hydroxy group

[0016] [Monomer (a1)] Monomer (a1) refers to 2-octyl(meth)acrylate and is represented by the following formula (1): Monomer (a1) is a biomass monomer. (Formula 1) [Chemistry] (R1 = H, CH3) The content of (a1) is 30% by mass or more and less than 95% by mass in 100% by mass of the monomer mixture. If the content of (a1) is less than 30% by mass, the adhesive force decreases, which is not preferable. The lower limit of the content of (a1) can obtain the desired effect if it is 30% by mass or more, preferably 35% by mass or more and less than 90% by mass, more preferably 40% by mass or more and less than 90% by mass, still more preferably 50% by mass or more and less than 90% by mass, and particularly preferably 55% by mass or more and less than 85% by mass. Also, the higher the content of (a1), the more preferable it is because it can contribute to the conservation of petroleum resources. The content of (a1) may be 30% by mass or more, 40% by mass or more, 50% by mass or more, and may be less than 95% by mass, less than 90% by mass, less than 85% by mass.

[0017] [Monomer (a2)] The monomer (a2) is a monomer having a carboxy group, and the content of (a2) is 1% by mass or more and less than 10% by mass in 100% by mass of the monomer mixture. If the content of the monomer (a2) is less than 1% by mass, the cohesive force decreases, which is not preferable. If it is 10% by mass or more, the flexibility is impaired, which is not preferable. Preferably, it is 2% by mass or more and less than 10% by mass in 100% by mass of the monomer mixture, more preferably 2% by mass or more and less than 7% by mass, still more preferably 2% by mass or more and less than 5% by mass, and particularly preferably 2% by mass or more and less than 4% by mass. The content of (a2) may be 1% by mass or more, 2% by mass or more, and may be less than 10% by mass, less than 7% by mass, less than 5% by mass, less than 4% by mass.

[0018] The monomer having a carboxy group is not limited as long as it has a carboxy group in the molecule. Specifically, (meth)acrylic acid, p-carboxybenzyl acrylate, β-carboxyethyl acrylate, maleic acid, monoethyl maleic acid, itaconic acid, citraconic acid, fumaric acid, etc. can be mentioned. Among these, (meth)acrylic acid is preferable from the viewpoint of adhesive force, and acrylic acid is more preferable.

[0019] [Monomer (a3)] Monomer (a3) is another monomer other than monomer (a1), monomer (a2) and monomer (a4), and is not particularly limited. Also, it is preferable to use a (meth)acrylate which is a biomass monomer in consideration of the environment for monomer (a3), and it is more preferable to use a (meth)acrylate having a high biomass degree.

[0020] The content of monomer (a3) is 4% by mass or more and less than 69% by mass in 100% by mass of the monomer mixture. It is preferably 4% by mass or more and less than 60% by mass. It is more preferably 5% by mass or more and less than 60% by mass, and still more preferably 10% by mass or more and less than 45% by mass. The content of (a3) may be 4% by mass or more, 5% by mass or more, 10% by mass or more, and may be less than 69% by mass, less than 60% by mass, less than 45% by mass.

[0021] Monomer (a3) preferably contains a monomer (excluding monomer (a2) and monomer (a4)) whose glass transition temperature of the homopolymer of monomer (a3-1) is 0°C or higher, or a monomer (a3-2) alkyl (meth)acrylate monomer (excluding monomer (a2) and monomer (a4)) having 2 to 8 carbon atoms in the alkyl group and a glass transition temperature of the homopolymer of less than 0°C. It is more preferable to contain monomer (a3-1), and still more preferable to contain monomer (a3-1) and monomer (a3-2) simultaneously. By containing monomer (a3-1), the cohesive force can be improved, and by containing monomer (a3-2), the fixed load peeling system can be improved. The glass transition temperature (°C) of the homopolymer can be known from information from the suppliers of various monomers or the values described in "Polymer Handbook 3rd Edition" (A WILEY-INTERSCIENCE PUBLICATION, 1989).

[0022] (Monomer (a3-1)) The monomer (a3-1) is not particularly limited as long as it is a monomer (excluding monomer (a2) and monomer (a4)) with a glass transition temperature of the homopolymer of 0 °C or higher. Examples of the monomer (a3-1) include acrylamide, N,N-dimethylacrylamide, methacrylonitrile, acrylonitrile, diacetone acrylamide, methyl (meth)acrylate, ethyl methacrylate, ter-butyl methacrylate, sec-butyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, isopropyl methacrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyl (meth)acrylate, and the like. In terms of improving cohesion and adhesion, the monomer (a3-1) is preferably at least one selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and phenyl (meth)acrylate. More preferably, (meth)acrylate, which is a biomass monomer, is used in consideration of the environment.

[0023] The content of the monomer (a3-1) is preferably 0.1% by mass or more and less than 69% by mass in 100% by mass of the monomer mixture. More preferably, it contains 0.1% by mass or more and less than 20% by mass, and even more preferably 1% by mass or more and less than 15% by mass. The content of (a3-2) may be 0.1% by mass or more, 1% by mass or more, and may be less than 69% by mass, less than 20% by mass, or less than 15% by mass.

[0024] (Monomer (a3-2)) Monomer (a3-2) is an alkyl (meth) acrylate monomer in which the alkyl group has 2 to 8 carbon atoms and the glass transition temperature of the homopolymer is less than 0°C (excluding monomers (a2) and (a4)). Examples of monomer (a3-2) include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isoamyl acrylate, and the like. In terms of improving the peel resistance under a constant load, monomer (a3-2) preferably contains at least one selected from the group consisting of isopropyl acrylate, isobutyl acrylate, isopentyl acrylate, and isoamyl acrylate. Further, it is more preferable to use a (meth) acrylate that is a biomass monomer considering the environment.

[0025] The content of (a3-2) is preferably 4% by mass or more and less than 69% by mass in 100% by mass of the monomer mixture. By containing 4% by mass or more and less than 69% by mass, the balance of cohesive force, adhesive force, and tackiness can be ensured. More preferably, it is 8% by mass or more and less than 60% by mass, still more preferably 10% by mass or more and less than 50% by mass, and particularly preferably 10% by mass or more and less than 42% by mass. The content of (a3-2) may be 4% by mass or more, 8% by mass or more, 10% by mass or more, and may be less than 69% by mass, less than 60% by mass, less than 50% by mass.

[0026] [Monomer (a4)] The monomer mixture constituting the acrylic polymer (A) may further contain less than 0.7% by mass of the monomer (a4) having a hydroxy group. It is more preferably contained in an amount of 0.03% by mass or more and less than 0.7% by mass, still more preferably contained in an amount of 0.05% by mass or more and less than 0.7% by mass, and particularly preferably contained in an amount of 0.05% by mass or more and less than 0.3% by mass. By containing the monomer (a4), the cohesive force of the adhesive layer is increased, and it becomes easier to balance the adhesive force and the peel resistance under a constant load. The content of (a4) may be 0.03% by mass or more, 0.05% by mass or more, and may be less than 0.7% by mass, less than 0.3% by mass.

[0027] The monomer (a4) is not limited as long as it is a monomer having a hydroxy group in the molecule. Specifically, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. can be mentioned. Among these, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable from the viewpoint of the balance between the adhesive force and the peel resistance under a constant load.

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

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

[0030] Azo compounds include, for example, 2,2'-azobisbutyronitrile such as 2,2'-azobisisobutyronitrile (abbreviation: AIBN), 2,2'-azobis(2-methylbutyronitrile); 2,2'-azobisvaleronitrile such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile); 2,2'-azobispropionitrile such as 2,2'-azobis(2-hydroxymethylpropionitrile); Examples thereof include 1,1'-azobis-1-alkanenitriles 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 acrylic polymer (A) is not particularly limited, but is preferably 2 million or less, more preferably 1 million or less, and even more preferably 800,000 or less. The weight-average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

[0033] >[A rosin-based tackifier resin (B1) having a softening point of 120° C. or higher] The rosin-based tackifier resin (B1) is not particularly limited as long as its softening point is 120° C. or higher. Examples thereof include rosin esters, polymerized rosins, hydrogenated rosins, disproportionated rosins, maleic acid-modified rosins, fumaric acid-modified rosins, rosin-phenol resins, and natural rosins.

[0034] The adhesive of the present disclosure contains 10 parts by mass or more and less than 60 parts by mass of a rosin-based tackifier resin (B1) having a softening point of 120° C. or higher with respect to 100 parts by mass of the acrylic polymer (A). If the content is less than 10 parts by mass, the adhesive strength becomes low, which is not preferable. If it is 60 parts by mass or more, the low-load peelability deteriorates, which is not preferable. It is preferably 15 parts by mass or more and less than 50 parts by mass, more preferably 20 parts by mass or more and less than 40 parts by mass, with respect to 100 parts by mass of the acrylic polymer (A). The content rate of (B1) may be 10 parts by mass or more, 15 parts by mass, 20 parts by mass or more, and may be less than 60 parts by mass, less than 50 parts by mass, or less than 4 parts by mass.

[0035] The hydroxyl value of the rosin-based tackifier resin (B1) is preferably 20 mgKOH / g or more. When the hydroxyl value is 20 mgKOH / g or more, a good bond is generated between the polymer and the rosin-based tackifier when using a curing agent, resulting in a suitable crosslinked structure. As a result, it is preferable because the peel resistance under a constant load is excellent.

[0036] Furthermore, it is more preferable to use a tackifier resin (B1) with a biomass content of 80% or more in consideration of the environment.

[0037] <A tackifier resin (B2) with a softening point of 90°C or higher and less than 120°C> The adhesive of the present disclosure preferably further contains 10 parts by mass or more and less than 60 parts by mass of a tackifier resin (B2) with a softening point of 90°C or higher and less than 120°C with respect to 100 parts by mass of the acrylic polymer (A). If the content is less than 10 parts by mass, the adhesive strength becomes low, which is not preferable. If it is 60 parts by mass or more, the low-load peel resistance deteriorates, which is not preferable. It is preferably 15% by mass or more and less than 50% by mass, more preferably 20% by mass or more and less than 45% by mass, with respect to 100 parts by mass of the acrylic polymer (A). The tackifier resin (B2) with a softening point of 90°C or higher and less than 120°C preferably contains at least one selected from the group consisting of rosin-based tackifier resins, aliphatic petroleum resins, aromatic petroleum resins, aliphatic / aromatic petroleum resins, and terpene-based tackifiers. More preferably, it contains at least one selected from the group consisting of rosin-based tackifier resins, aliphatic petroleum resins, aromatic petroleum resins, and aliphatic / aromatic petroleum resins.

[0038] Examples of the rosin-based tackifier resin include the same materials as those described for the rosin-based tackifier resin with a softening point of 120°C or higher.

[0039] 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 ENEOS Materials Corporation; examples of aliphatic / aromatic petroleum resins include FTR6100 manufactured by Mitsui Chemicals, Inc.; and examples of rosin derivatives include Sylvatac RE85 manufactured by Arizona Chemical Company and Super Ester A-75 manufactured by Arakawa Chemical Industries, Ltd.

[0040] 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.

[0041] The biomass degree of the tackifier resin (B2) is not particularly limited, but is preferably 50% or more, more preferably 80% or more.

[0042] <Curing agent (C)> The pressure-sensitive adhesive of the present disclosure contains a curing agent (C), and any curing agent (C) can be used without particular limitation as long as it provides a crosslinked structure to the pressure-sensitive adhesive. The incorporation of the curing agent (C) improves the cohesive strength of the pressure-sensitive adhesive layer, and improves the adhesive strength, heat resistance, and light resistance. The curing agent (C) preferably contains at least one selected from the group consisting of an isocyanate-based curing agent, an epoxy-based curing agent, and an aluminum chelate-based curing agent. By including at least one selected from the group consisting of an isocyanate-based curing agent, an epoxy-based curing agent, and an aluminum chelate-based curing agent, the cohesive strength of the adhesive can be appropriately increased and other physical properties are less likely to be adversely affected, which is preferable. As long as at least one of an isocyanate-based curing agent, an epoxy-based curing agent, and an aluminum chelate-based curing agent is included, known curing agents other than an isocyanate-based curing agent, an epoxy-based curing agent, and an aluminum chelate-based curing agent may be used in combination.

[0043] The isocyanate-based curing agent is an isocyanate having two or more isocyanate groups. Examples of the isocyanate include aromatic polyisocyanate-based, aliphatic polyisocyanate, araliphatic polyisocyanate, alicyclic polyisocyanate, and their burette bodies, nurate bodies, and adduct bodies. From the viewpoint of yellowing resistance, aliphatic polyisocyanate, alicyclic polyisocyanate, and their burette bodies, nurate bodies, and adduct bodies are more preferable.

[0044] Examples of the aromatic polyisocyanate 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, 4,4',4''-triphenylmethane triisocyanate, and the like.

[0045] Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (alias: HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and the like.

[0046] Examples of the araliphatic polyisocyanate include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, and the like.

[0047] Aliphatic polyisocyanates include, for example, 3-isocyanatomethyl-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), 1,4-bis(isocyanatomethyl)cyclohexane, and the like.

[0048] The burette body is a self-condensate having a burette bond formed by self-condensation of isocyanate monomers. Examples of the burette body include the burette body of hexamethylene diisocyanate.

[0049] The nurate body is a trimer of isocyanate monomers. Examples include trimers of hexamethylene diisocyanate, trimers of isophorone diisocyanate, trimers of tolylene diisocyanate, and the like.

[0050] The adduct body is a polyfunctional isocyanate compound formed by the reaction of an isocyanate monomer with a polyfunctional low-molecular-weight active hydrogen-containing compound. Examples of the adduct body include compounds obtained by reacting trimethylolpropane with hexamethylene diisocyanate, compounds obtained by reacting trimethylolpropane with tolylene diisocyanate, compounds obtained by reacting trimethylolpropane with xylylene diisocyanate, compounds obtained by reacting trimethylolpropane with isophorone diisocyanate, compounds obtained by reacting 1,6-hexanediol with hexamethylene diisocyanate, and the like.

[0051] From the perspective of forming a sufficient crosslinked structure, a trifunctional isocyanate compound is preferred as the isocyanate compound. More preferably, the isocyanate compound is an adduct obtained by reacting an isocyanate monomer with a trifunctional low-molecular-weight active hydrogen-containing compound, or a nurate. Preferred isocyanate compounds include trimethylolpropane adducts of hexamethylene diisocyanate, nurates of hexamethylene diisocyanate, trimethylolpropane adducts of tolylene diisocyanate, nurates of tolylene diisocyanate, trimethylolpropane adducts of isophorone diisocyanate, and nurates of isophorone diisocyanate. More preferred are trimethylolpropane adducts of hexamethylene diisocyanate, trimethylolpropane adducts of tolylene diisocyanate, and trimethylolpropane adducts of isophorone diisocyanate.

[0052] 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, N,N,N',N'-tetraglycidylaminophenylmethane, and the like. The aluminum chelate curing agent is not particularly limited as long as it is an aluminum compound having a chelate ligand and capable of forming a crosslinked structure with the crosslinkable resin. The chelate ligand may be a bidentate ligand or a multidentate ligand having three or more seats. Examples thereof include β-diketonates such as acetylacetonate, benzoylacetonate, and methylacetylacetonate; β-ketoester anions such as methyl acetoacetate and ethyl acetoacetate; and the like.

[0053] Specific examples of the aluminum chelate curing agent include aluminum (ethyl acetoacetate) diisopropylate, aluminum tris(acetylacetonate), aluminum tris(ethyl acetoacetate), aluminum bis(ethyl acetoacetate) mono(acetylacetonate), and the like. These aluminum chelate curing agents may be used either individually or in combination of two or more.

[0054] The curing agent (C) is preferably contained in an amount of 0.02 to 6 parts by mass, and more preferably 0.04 to 1 part by mass, per 100 parts by mass of the acrylic polymer (A). A content of 0.02 part by mass or more further improves the cohesive strength, and a content of 1 part by mass or less is preferred because it is easier to achieve both cohesive strength and flexibility.

[0055] (optional ingredient) The pressure-sensitive adhesive 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 copolymer. From the viewpoints of good compatibility with acrylic polymers and the like and effective reduction of polarity, chlorinated polypropylene and chlorinated ethylene vinyl acetate copolymer are preferred. Specific examples of commercially available products include Superchlorine 390S (chlorinated polypropylene, chlorine content 36%) and Superchlorine BX (chlorinated EVA, chlorine content 18%) (both manufactured by Nippon Paper Industries Co., Ltd.).

[0057] The pressure-sensitive adhesive of the present disclosure preferably has a gel fraction of 10% or more and less than 50%, more preferably 30% or more and less than 50%. The method for measuring the gel fraction will be described in detail in the Examples.

[0058] <Adhesive layer> The pressure-sensitive adhesive layer is a layer obtained from the pressure-sensitive adhesive of the present disclosure. There are no particular limitations on the method for forming the pressure-sensitive adhesive layer, and it can be the same as the coating method described below in the description of the pressure-sensitive adhesive sheet.

[0059] The pressure-sensitive adhesive sheet of the present disclosure preferably has a higher adhesive strength of SUS for the fixity of the product and the like. Depending on the product, it is possible to use it with a low adhesive strength, but for multi-purpose use, it is preferably 2 N / 25 mm or more as the peel strength, more preferably 10 N / 25 mm or more, and even more preferably 15 N / 25 mm or more. The measurement method will be described in detail in the examples. The pressure-sensitive adhesive sheet of the present disclosure preferably has a higher adhesive strength of PE for the fixity of the product and the like. Depending on the product, it is possible to use it with a low adhesive strength, but for multi-purpose use, it is preferably 2 N / 25 mm or more as the peel strength, more preferably 5 N / 25 mm or more, and even more preferably 10 N / 25 mm or more. The measurement method will be described in detail in the examples. The pressure-sensitive adhesive sheet of the present disclosure preferably has a high holding power. Depending on the product, it is possible to use it with a low holding power, but for multi-purpose use, it is more preferable that the displacement when a load is applied is less. The pressure-sensitive adhesive sheet of the present disclosure preferably has a high peel resistance under a constant load. Depending on the product, it is possible to use it with a low peel resistance under a constant load, but for multi-purpose use, it is more preferable that the displacement when a load is applied is less. The pressure-sensitive adhesive sheet of the present disclosure preferably has a high ball tack. Depending on the product, it is possible to use it with a low ball tack, but for multi-purpose use, it is preferably a higher tack.

[0060] ≪Pressure-sensitive adhesive sheet≫ The pressure-sensitive adhesive sheet includes the pressure-sensitive adhesive of the present disclosure or a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive and a release film.

[0061] The pressure-sensitive adhesive sheet of the present disclosure may have any configuration in which a release film is formed on one or both sides of the pressure-sensitive adhesive layer.

[0062] <Release film> Although there are no particular restrictions on the release film, a transparent plastic substrate can be preferably used. Examples of the material of the transparent plastic substrate include plastics such as polyester such as polyethylene terephthalate (PET), acrylic resin such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose, polysulfone, polyarylate, and polycycloolefin. The plastic materials can be used alone or in combination of two or more.

[0063] As the release film, among the transparent plastic substrates as described above, a transparent plastic substrate having excellent heat resistance, that is, a transparent plastic substrate in which deformation is suppressed or prevented under severe conditions such as high temperature and high temperature and high humidity can be preferably used. As the transparent plastic substrate, a PET film or sheet is particularly preferable.

[0064] The thickness of the release film is preferably less than 200 μm. Although the thickness should be adjusted by handling the members to be used, being less than 200 μm makes the texture of the material not too firm, facilitates winding into a roll shape, and can be used comfortably when laminating with a sheet or the like.

[0065] The pressure-sensitive adhesive sheet of the present disclosure has excellent adhesiveness, and thus is suitable for forming optical display members such as display devices such as LCDs and OLEDs and input devices such as touch panels, and for bonding these members together. The optical member is not particularly limited, and examples thereof include a PET film, a polarizing plate, a retardation plate, an elliptical polarizing plate, an optical compensation film, a brightness enhancement film, an infrared / electromagnetic wave cut film, an antireflection film for the front surface, a surface protection film, a film having an ITO (indium tin oxide) layer, a film having a zinc oxide (ZnO) layer, a film obtained by applying or printing metal nanoparticles, a film obtained by applying or printing a dispersion containing carbon nanotubes, a film obtained by applying or printing a dispersion containing graphene, a film obtained by applying or printing a dispersion containing a conductive polymer, a metal plate formed of SUS or the like, a metal mesh, and those in which these are laminated.

[0066] For the pressure-sensitive adhesive or the coating of the pressure-sensitive adhesive, an appropriate liquid medium can be added to adjust the viscosity. Specifically, for example, 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 and the like can be mentioned. However, water and alcohol need to be used carefully because they may cause inhibition of the reaction between the acrylic polymer (A) and the isocyanate-based curing agent (B).

[0067] The coating method is not particularly limited, and various coating methods such as a Meyer bar, an applicator, a brush, a spray, a roller, a gravure coater, a die coater, a lip coater, a comma coater, a knife coater, a reverse coater, and a spin coater can be mentioned. Also, the drying and curing method is not particularly limited, and examples thereof include hot air drying, infrared rays, a vacuum method, and those using active energy rays. However, from the viewpoint of outgas resistance, hot air or steam heating at 60 to 180°C is preferable.

[0068] ≪Laminate≫ The laminate of the present disclosure includes a base material and an adhesive layer. The adhesive layer is formed using the adhesive sheet of the present disclosure. Specifically, for example, the release film can be peeled off from the adhesive sheet of the present disclosure, and the adhesive layer can be attached to the base material to form a laminate.

[0069] <Base material> The base material refers to the object to which the adhesive layer of the adhesive sheet having the adhesive layer is attached, and is not limited to a specific one. As an example, polyolefins including polyethylene, polypropylene, etc., resins such as polycarbonate, phenol, etc., metals such as iron, stainless steel (SUS), aluminum, copper, etc., and other cement, mortar, glass, non-woven fabric, woven fabric, paper, rubber, foam sheet, laminates of these, etc. can be used. The adhesive and the adhesive of the present disclosure exhibit excellent adhesive force to at least one type of adherend.

[0070] The basis weight of the base material is preferably less than 500 g / m 2 and more preferably less than 230 g / m 2 of the base material is preferably less than 500 g / m and more preferably less than 230 g / m.

[0071] The laminate of the present disclosure can also use a light-transmissive base material as the base material. As the light-transmissive base material, a transparent plastic base material is used. Examples of such materials for the light-transmissive base material include acrylic resins such as polyethylene terephthalate (PET), polyethylene naphthalate, polymethyl methacrylate (PMMA), polycarbonate (PC), polycycloolefin, polyimide, polyphenylene ether, polysulfone, polyethersulfone, polystyrene, polypropylene, etc. plastic materials. PET film or PC is preferred, and PC is more preferred in terms of durability. Note that the plastic materials can be used alone or in combination of two or more. In addition, the light-transmissive base material may be subjected to appropriate surface treatments such as physical treatments such as corona discharge treatment, plasma treatment, etc., and chemical treatments such as undercoat treatment.

[0072] FIG. 1 shows an example of a schematic cross-sectional view partially showing the laminate of the present disclosure. In FIG. 1, 1 is an adhesive layer, 2 is a release film, and 3 is a base material.

[0073] <Manufacture of laminate> The method for manufacturing a laminate can, for example, form a laminate by peeling a release film from an adhesive sheet having release films on both sides of an adhesive layer and attaching the adhesive layer to a base material such as a PET base material or a foam sheet, respectively. Also, after directly forming an adhesive layer on various base materials, a laminate can be formed by attaching a base material or an adhesive layer provided on another adhesive sheet to the adhesive layer.

[0074] In view of the current trend towards environmentally friendly materials, the adhesive of the present disclosure can be an adhesive or an adhesive that is partially or entirely made of bio-derived materials by using a biomass monomer as a monomer constituting the acrylic polymer (A) or by using a biomass tackifier. The biomass content is preferably 30% or more. More preferably 39% or more, and even more preferably 60% or more. The higher the biomass content, the higher the usefulness as an environmentally friendly material. The method for calculating the biomass content is described in the examples.

Examples

[0075] Hereinafter, the present disclosure will be described more specifically by way of examples, but the present disclosure is not limited to these examples. In the examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass". Also, the compounding amounts in the tables are in parts by mass, and except for solvents, they are values in terms of non-volatile content. Note that the blanks in the tables indicate that nothing is compounded.

[0076] <Manufacturing example of acrylic polymer> Acrylic polymer (A-1) Using a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping tube, 30 parts of 2-octyl acrylate (2OA) as monomer (a1), 1 part of acrylic acid as monomer (a2), 68.8 parts of ethyl acrylate as monomer (a3), 0.2 part of 2-hydroxyethyl acrylate (HEA) as monomer (a4), and 110 parts of ethyl acetate as a solvent were charged into the reaction vessel. Polymerization was carried out at 70 °C for 5 hours under a nitrogen atmosphere, and the viscosity was appropriately adjusted by dropping ethyl acetate during the polymerization. After completion of the reaction, it was cooled and appropriately diluted with ethyl acetate to obtain an acrylic polymer solution (A-1).

[0077] (Acrylic polymers (A-2 to A-32) Acrylic polymers (A-2 to A-32) were synthesized in the same manner as the production of acrylic polymer (A-1), except that the composition and blending amount (parts by mass) shown in Table 1 were changed.

[0078]

Table 1

[0079]

Table 1

[0080] The abbreviations are as follows. Note that the description is only for those confirmed regarding the biomass content. [Monomer (a1)] 2OA: 2-Octyl acrylate (biomass content 73%) 2OMA: 2-Octyl methacrylate (biomass content 67%) [Monomer (a2)] AA: Acrylic acid MAA: Methacrylic acid [Monomer (a3)] MA: Methyl acrylate (Tg: 8 °C) MMA: Methyl methacrylate (Tg: 105 °C) IBXA: Isobornyl acrylate (Tg: 97 °C, biomass content 76%) BMA: Butyl methacrylate (Tg: 20 °C) EA: Ethyl acrylate (Tg: -22 °C) BA: n-Butyl acrylate (Tg: -55 °C) iBA: Isobutyl acrylate (Tg: -26 °C) HA: n-Hexyl acrylate (Tg: -60 °C, biomass content 64%) 2EHA: 2-Ethylhexyl acrylate (Tg: -70 °C) sBA: sec-Butyl acrylate (Tg: -20 °C) LA: Lauryl acrylate (Tg: -23 °C, biomass content 80%) [Monomer (a4)] HEA: Hydroxyethyl acrylate 4HBA: 4-Hydroxynormal butyl acrylate

[0081] <Example 1> To 100 parts of acrylic polymer (A-1), 30 parts of Pencil D-125 (Arakawa Chemical Industries, Ltd., polymerized rosin ester) was added as tackifier (B1), and 2 parts of "Coronate L" (manufactured by Tosoh Corporation, trimethylolpropane-modified toluene diisocyanate) was blended as curing agent (C) to obtain an adhesive. The obtained adhesive was coated on a release sheet made of polyethylene terephthalate with a thickness of 38 μm (Serapil MF: manufactured by Toray Film Processing Co., Ltd.) using a comma coater so that the dried thickness would be 50 μm, and dried at 100 °C for 2 minutes to obtain a pressure-sensitive adhesive sheet. Next, one side of a polyethylene terephthalate film with a thickness of 50 μm (hereinafter referred to as PET film, product name: A-4300, manufactured by Toyobo Co., Ltd.) was laminated on the adhesive surface of this pressure-sensitive adhesive sheet to obtain a laminate having a structure of "release sheet / adhesive layer / PET film". Next, the obtained laminate was aged for 1 week under the conditions of a temperature of 25 °C and a relative humidity of 55% to obtain a pressure-sensitive adhesive sheet.

[0082] <Examples 2 to 37, Comparative Examples 1 to 13> As shown in Table 2, an adhesive sheet was obtained in the same manner as in Example 1, except that the types and blending amounts of the acrylic polymer, curing agent, and tackifier resin were changed.

[0083] <Gel fraction measurement> The 38-μm release liner of the obtained adhesive sheet was peeled off, and the adhesive layer was laminated onto a PET film (manufactured by Toyobo Co., Ltd., Cosmo Shine A-4360, thickness 100 μm) serving as a base material, and a test adhesive sheet having a size of 30 mm in width × 100 mm in length was prepared. Further, the release liner on the other surface of the adhesive tape was peeled off to prepare a test piece, and the weight was measured. The test piece was immersed in ethyl acetate at 23°C for 24 hours, then taken out from ethyl acetate and dried under the condition of 150°C for 30 minutes. The weight of the dried test piece was measured, and the gel fraction was calculated using the following formula (1). In Table 2, "10 - 50%" means that the gel fraction is 10% or more and 50% or less, and "50% <" means that the gel fraction exceeds 50%. Gel fraction (wt%) = 100 × (W2 - W0) / (W1 - W0) ···· (1) (W0: weight of the base material (PET film), W1: weight of the test piece before immersion, W2: weight of the test piece after immersion and drying)

[0084] <Calculation of biomass content> The biomass content of the adhesive was calculated using the following formula (2). (In the case of a two-component monomer (A, B) and one-component tackifier (C) system) Biomass content = {(Aw × Ab) + (Bw × Bb) + (Cw × Cb)} / (Aw + Bw + Cw) ···· (2) Aw: weight of monomer A, Bw: weight of monomer B, Cw: weight of tackifier Ab: biomass content of monomer A (%), Bb: biomass content of monomer B (%), Cb: biomass content of monomer C (%), When the biomass content is within a specified range, the minimum value is used for the above calculation.

[0085] The materials used in the examples and comparative examples are described below.

[0086] <Adhesion - imparting resin (B1)> D - 125: (Brush D - 125, Arakawa Chemical Industries, Ltd., polymerized rosin ester, biomass content 89%, softening point 125°C, hydroxyl value 32 - 33 mgKOH / g) YS - T130: (YS Polyster T130, Yasuhara Chemical Co., Ltd., terpene phenol, biomass content 65%, softening point 130°C, hydroxyl value 80 mgKOH / g) A - 125: (Super Ester A - 125, Arakawa Chemical Industries, Ltd., polymerized rosin ester, biomass content 80 - 94%, softening point 125°C, hydroxyl value 15 mgKOH / g)

[0087] <Adhesion - imparting resin (B2)> A - 100: (Super Ester A - 100, Arakawa Chemical Industries, Ltd., polymerized rosin ester, biomass content 99%, softening point 100°C, hydroxyl value 15) YS - T115: (YS Polyster T115, Yasuhara Chemical Co., Ltd., terpene phenol, biomass content 60%, softening point 115°C, hydroxyl value 40 or more) FTR6100: (Mitsui Chemicals, Inc., aliphatic / aromatic petroleum resin, biomass content 0%, softening point 95°C, hydroxyl value 10 or less) <Hardener (C)> Coronate L: Manufactured by Tosoh Corporation, trimethylolpropane adduct of toluene diisocyanate Tetrad X: Manufactured by Mitsubishi Gas Chemical Company, Inc., polyfunctional epoxy resin Aluminum chelate A: Manufactured by Kawaken Fine Chemicals Co., Ltd., chelate hardener

[0088] The evaluation of the examples and comparative examples was carried out according to the following methods and evaluation criteria. The results are described in accordance with Table 2.

[0089] <SUS Adhesion> The 38-μm release liner of the obtained adhesive sheet was peeled off, and in an atmosphere of 23°C and 50% relative humidity (50% RH), the adhesive layer was attached to a SUS plate and further crimped with a roll in accordance with JIS Z-0237. After 24 hours had elapsed since crimping, the peel strength (peel angle: 180°, peel rate: 300 mm / min; unit: N / 25 mm width) was measured using a tensile testing machine (Tensilon, manufactured by Orientec Co., Ltd.). [Evaluation Criteria] A: Peel strength is 15 N / 25 mm or more. : Good B: Peel strength is 10 N / 25 mm or more and less than 15 N / 25 mm. : Slightly good C: Peel strength is 2 N / 25 mm or more and less than 10 N / 25 mm. : Usable D: Peel strength is less than 2 N / 25 mm. : Unusable

[0090] <PE Adhesion>[[]] Measurement was carried out in the same manner as the above glass adhesion measurement, except that the adherend was changed from a SUS plate to a PE plate.[[]] [Evaluation Criteria] A: Peel strength is 10 N / 25 mm or more. : Good B: Peel strength is 5 N / 25 mm or more and less than 10 N / 25 mm. : Slightly good C: Peel strength is 2 N / 25 mm or more and less than 5 N / 25 mm. : Usable D: Peel strength is less than 2 N / 25 mm. : Unusable

[0091] <Retention Force>[[]] An adhesive sheet with a width of 25 mm and a length of 150 mm was prepared. The adhesive layer exposed by peeling off the release sheet from the adhesive sheet was attached to a portion with a width of 25 mm and a length of 25 mm at the lower end of a stainless steel plate with a width of 30 mm and a length of 150 mm that had been polished. After crimping back and forth once with a 2-kg roll, a load of 1 kg was applied to the lower end of the adhesive sheet in an 80°C atmosphere, and the retention force was measured by leaving it for 70,000 seconds (in accordance with JIS Z0237:2000). For the evaluation, the length by which the upper end portion of the adhesive sheet attachment surface shifted downward from the original position was measured.[[]] [Evaluation Criteria] A: The shifted length is less than 3 mm: Good B: The shifted length is 3 mm or more and less than 7 mm: Slightly good​​ C: Deviated length is 7 mm or more and less than 10 mm: Usable D: Deviated length is 10 mm or more or dropped: Unusable

[0092] <Constant load peel resistance> This will be described with reference to Fig. 2. In an atmosphere of 23 °C (relative humidity 50%), an 80 mm long portion of an adhesive sheet (2) cut to a length of 100 mm × width of 25 mm was adhered to a propylene plate (product name "Kobe Poly Sheet PP", manufactured by Yamane Shoten) which is an adherend plate (1). After that, it was pressure-bonded 2 times back and forth with a 2 kg roll and left in an atmosphere of 23 °C (relative humidity 50%) for 24 hours. Then, a 100 g weight (3) was attached to the non-adhered portion of the adhesive sheet (2) in an atmosphere of 80 °C, a load was applied in a direction perpendicular to the surface of the adherend plate (1), and the length by which the adhesive sheet peeled from the adherend after 24 hours was measured. When it completely peeled off and the length could not be measured, the time until it dropped was measured. The length between A and B in Fig. 2 represents the peeled length. Among those that did not drop, those with a shorter peeled length are better. Also, among those that dropped, those with a longer time until dropping are better. [Evaluation criteria] S: Peeled length is less than 10 mm: Excellent [[ID=X]] A: Peeled length is 10 mm or more and less than 20 mm: Good B: Peeled length is 20 mm or more and less than 40 mm: Fair C: Peeled length is 40 mm or more and did not drop: Usable D: Dropped: Unusable

[0093] <Ball tack> The evaluation of ball tack was carried out in accordance with JIS Z0237. The obtained adhesive sheet was cut to a length of 100 mm to obtain a test piece. Subsequently, the separator film was peeled from the test piece, and the test piece was placed on an inclined plane with an inclination angle of 30° so that the exposed adhesive layer faced upward. Steel balls from No. 2 (2 / 32 inch) to No. 32 (32 / 32 inch) were rolled in order from a position 100 mm in front of the test piece. Among the steel balls that stopped on the test piece at this time, the number of the steel ball with the largest diameter was taken as the tack value. Note: There seems to be a missing ID "X" in the original text's ID sequence which is maintained in the translation for consistency. If this is an error in the original, it should be corrected accordingly. [Evaluation Criteria] A: No. 5 or above: Good B: No. 3 or above and less than No. 5: Slightly good C: No. 2 or above and less than No. 3: Usable D: Less than No. 2: Unusable

[0094] [Table 2]

[0095] [Table 2]

[0096] The present invention has been described with reference to several of the above embodiments, but the present invention is not limited to these embodiments. Various changes can be made to the configuration and details of the present invention within the scope of the present invention.

[0097] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2023-144832 filed on September 6, 2023, Japanese Patent Application No. 2023-181269 filed on October 20, 2023, and Japanese Patent Application No. 2024-019160 filed on February 13, 2024, and all of the disclosure contents thereof are incorporated herein by reference. [Explanation of Reference Numerals]

[0098] The reference numerals in FIG. 1 are explained below. 1 Adhesive layer, 2 Release film, 3 Substrate The reference numerals in FIG. 2 are explained below. (1) Adherend plate, (2) Adhesive sheet, (3) Weight

Claims

1. An adhesive comprising an acrylic polymer (A) which is a copolymer of a monomer mixture, a rosin-based tackifier resin (B1) having a softening point of 120° C. or higher, and a curing agent (C), wherein the content of the rosin-based tackifier resin (B1) relative to 100 parts by mass of the acrylic polymer (A) is 10 parts by mass or more and less than 60 parts by mass, in 100% by mass of the monomer mixture, the following monomer (a1) is 30% by mass or more and less than 95% by mass, the following monomer (a2) is 1% by mass or more and less than 10% by mass, the following monomer (a3) is 4% by mass or more and 69% by mass or less, and furthermore, the adhesive contains 0.03% by mass or more and less than 0.7% by mass of the following monomer (a4). (a1) 2-octyl (meth) acrylate (a2) an acrylic monomer having a carboxy group (a3) other acrylic monomers other than monomer (a1), monomer (a2), and monomer (a4) (a4) an acrylic monomer having a hydroxy group

2. The adhesive according to claim 1, wherein monomer (a3) contains a monomer (a3-1) (excluding monomer (a2) and monomer (a4)) having a glass transition temperature of the homopolymer of 0° C. or higher.

3. The adhesive according to claim 1, wherein monomer (a3) contains an alkyl (meth) acrylate monomer (a3-2) (excluding monomer (a2) and monomer (a4)) having 2 to 8 carbon atoms in the alkyl group and a glass transition temperature of the homopolymer of less than 0° C.

4. The adhesive according to claim 1, wherein the biomass content is 30% or more.

5. The adhesive according to claim 1, wherein the biomass content of the rosin-based tackifier resin (B1) is 80% or more.

6. The adhesive according to claim 1, wherein the hydroxyl value of the rosin-based tackifier resin (B1) is 20 mgKOH / g or more.

7. Furthermore, it contains 10 parts by mass or more and less than 60 parts by mass of a tackifier resin (B2) having a softening point of 90° C. or higher and less than 120° C. relative to 100 parts by mass of the acrylic polymer (A), The adhesive according to claim 1, wherein the tackifier resin (B2) contains at least one selected from the group consisting of a rosin-based tackifier resin, an aliphatic petroleum resin, an aromatic petroleum resin, an aliphatic / aromatic petroleum resin, and a terpene-based tackifier.

8. The adhesive according to claim 1, wherein the curing agent (C) contains at least one selected from the group consisting of an isocyanate-based curing agent, an epoxy-based curing agent, and an aluminum chelate-based curing agent. **Claim 9** The pressure-sensitive adhesive according to claim 8, wherein the gel fraction is less than 50%. **Claim 10** A pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive according to any one of claims 1 to 9. **Claim 11** The pressure-sensitive adhesive layer according to claim 10, wherein the SUS adhesive strength is 10 N / 25 mm or more. **Claim 12** The pressure-sensitive adhesive layer according to claim 10, wherein the PE adhesive strength is 5 N / 25 mm or more. **Claim 13** A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to claim 10 and a release film. **Claim 14** The pressure-sensitive adhesive sheet according to claim 13, wherein the thickness of the release film is less than 200 μm. **Claim 15** A laminate comprising the pressure-sensitive adhesive layer according to claim 10 and a substrate. **Claim 16** The laminated body according to claim 15, wherein the basis weight of the base material is less than 230 g / m ２ 2

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