TWI814010B - Adhesive composition, adhesive layer and adhesive film - Google Patents

Abstract

The invention provides an adhesive composition, an adhesive layer and an adhesive film. The adhesive composition includes an acrylic polymer (A), a cross-linking agent (B) and a plasticizer (C). The acrylic polymer (A) ) contains units derived from alkyl (meth)acrylate (a1), units derived from nitrogen-containing monomers (a2), and units derived from monomers (a3) containing oxygen-containing alkylene chains, derived from The content rate of units of the nitrogen-containing monomer (a2) in the acrylic polymer (A) is 2 mass % or more, and the cross-linking agent (B) contains a metal chelate cross-linking agent (b1). The adhesive composition has little increase in adhesive force even after being exposed to high temperature and high humidity conditions, and there is little contamination on the surface of the adherend after peeling off from the adherend, so it can be suitably used for adhesives and protection. in the membrane.

Description

Adhesive compositions, adhesive layers and adhesive films

The invention relates to an adhesive composition, an adhesive layer and an adhesive film.

Adhesive sheets are used in various fields such as automobiles, construction, and electronic equipment. In particular, in recent years, they have been effectively used in various situations such as surface protection of portable electronic devices such as tablets and smartphones, fixation of components, and protection during processing steps of used components.

As such an adhesive sheet, for example, a transparent adhesive film using a polymer containing a unit derived from an alkyl (meth)acrylate and a unit derived from a saturated cyclic group has been proposed. monomer unit (Patent Document 1); an adhesive using a (meth)acrylic acid alkyl ester monomer, an aromatic group-containing (meth)acrylate monomer, and a nitrogen-containing vinyl group that does not have a hydroxyl group Acrylic polymers formed from monomers, vinyl monomers having carboxyl groups, etc. (Patent Documents 2 to 7). [Prior art documents] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2017-48328 [Patent Document 2] Japanese Patent Application Publication No. 2019-70148 [Patent Document 3] Japanese Patent Application Publication No. 2019-70149 [Patent Document 4] Japanese Patent Application Publication No. 2019-70152 [Patent Document 5] Japanese Patent Application Publication No. 2019-77881 [Patent Document 6] Japanese Patent Application Laid-Open No. 2019-77882 [Patent Document 7] Japanese Patent Application Publication No. 2019-90040

[Problem to be solved by the invention] Components used in electronic equipment require a higher degree of processing and are therefore processed under more severe conditions than before. Therefore, the surface protective film used in the processing steps of these components needs to be able to be cleanly peeled off from the components after the processing step, even after being exposed to severe conditions such as high temperatures. Therefore, this kind of protective film is required to have characteristics such that the adhesive force does not increase as much after the thermal process, and the adhesive sheet is peeled off from the surface of the adherend so as not to contaminate the adherend with residual adhesive, etc. However, it is sometimes difficult for conventionally known adhesive sheets to achieve the above characteristics when placed under more severe processing conditions (high temperature, high humidity).

In addition, in the past, the protective film used in the processing steps was affixed and replaced for each step, and the used protective film was discarded. However, in recent years, in terms of reducing environmental load and reducing costs, there are requirements for multiple aspects. The use in the process requires that the stated characteristics can be achieved even when repeatedly exposed to harsh processing conditions (high temperature, high humidity).

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide an adhesive that exhibits less increase in adhesive force even after being repeatedly exposed to high temperature and high humidity conditions, and that causes less contamination of the surface of the adherend after peeling off from the adherend. agents and adhesive tapes. [Technical means to solve problems]

The inventors of the present invention conducted research and found that by using an acrylic polymer of a specific composition, it is possible to provide an adhesive that has less increase in adhesive force even after being exposed to high temperature and high humidity conditions and that peels off from the adherend. Adhesive with less contamination on the sticky surface.

That is, the adhesive composition of the present invention is characterized by containing: an acrylic polymer (A), a cross-linking agent (B), and a plasticizer (C). The acrylic polymer (A) contains an acrylic polymer derived from (methyl) Units of alkyl acrylate (a1), units derived from nitrogen-containing monomer (a2), and units derived from monomer (a3) containing oxygen-containing alkylene chain, units derived from nitrogen-containing monomer (a2) The content rate of units in the acrylic polymer (A) is 2 mass % or more, the cross-linking agent (B) contains a metal chelate cross-linking agent (b1), and the plasticizer (C) contains An esterification product of a compound (c1) having a hydroxyl group and a compound (c2) having an acid group, the plasticizer (C) having a solubility parameter value (SP value) (Small formula) of 10 (cal/cm ³ ) ^1/2 or less, and the number average molecular weight of the plasticizer (C) is 6,000 or less. [Effects of the invention]

According to the present invention, it is possible to provide an adhesive and an adhesive tape that have little increase in adhesive force even after repeated exposure to high temperature and high humidity conditions, and less contamination of the adherend surface after peeling off from the adherend.

The adhesive composition of the present invention includes an acrylic polymer (A), a cross-linking agent (B) and a plasticizer (C).

The acrylic polymer (A) contains units derived from (meth)acrylic acid alkyl ester (a1), units derived from nitrogen-containing monomers (a2), and monomers derived from oxygen-containing alkyl chains ( a3) unit.

Examples of (meth)acrylic acid alkyl esters (a1) include (meth)acrylic acid alkyl esters in which an alkyl group is bonded to an ester bond. The number of carbon atoms of the alkyl group is preferably 1 or more, more preferably 3 or more, still more preferably 4 or more, and preferably 20 or less, more preferably 15 or less, further preferably 12 or less, still more preferably 10 or less, Particularly preferably, it is 8 or less.

The alkyl (meth)acrylate (a1) is preferably an alkyl (meth)acrylate (a1-1) containing an alkyl group having 3 or more carbon atoms (preferably 4 or more) bonded to an ester bond. ). The content rate of the alkyl (meth)acrylate (a1-1) in the alkyl (meth)acrylate (a1) is preferably 50 mass% or more, more preferably 60 mass% or more, and still more preferably 70 Mass% or more, and preferably 100 mass% or less.

The alkyl (meth)acrylate (a1) is preferably an alkyl (meth)acrylate (a1-2) in which an alkyl group having 2 or less carbon atoms is bonded to an ester bond. When the alkyl (meth)acrylate (a1-2) is included, its content is preferably 1 mass % or more, more preferably 2 mass % or more, and preferably 50 mass % or less, more preferably 40 mass %. % or less, and more preferably 30 mass% or less.

Examples of the alkyl group include: methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, lauryl, hard Aliphatic and other linear alkyl groups; isopropyl, isobutyl, tert-butyl, isopentyl, neopentyl, isohexyl, isoheptyl, isooctyl, 2-ethylhexyl, isononyl, Branched chain alkyl groups such as isodecyl and isostearyl.

The (meth)acrylic acid alkyl ester (a1) is preferably an acrylic acid alkyl ester.

As the (meth)acrylic acid alkyl ester (a1), one or two or more kinds can be used, and examples include: (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester , n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate Ester, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, ( n-decyl methacrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, etc.

In the acrylic polymer (A), the content of units derived from the alkyl (meth)acrylate (a1) is preferably 50 mass % or more, more preferably 60 mass % or more, and preferably 98 mass %. % or less, more preferably 95 mass% or less.

The nitrogen-containing monomer (a2) is a monomer having a nitrogen atom and a polymerizable double bond in the molecule, preferably a monomer having an amide bond and a polymerizable double bond in the molecule, for example: having a vinyl group Lactam compound; (meth)acrylamide monomer; (meth)acrylic acid having a functional group containing a nitrogen atom (for example, amino group, 1-substituted amino group, 2-substituted amino group, nitrile group, etc.) Ester compounds, etc.

Examples of the lactam compound having a vinyl group include N-vinylpyrrolidone, N-vinylcaprolactam, and the like.

The (meth)acrylamide monomer can include: a hydrogen atom or a hydrocarbon group (preferably an aliphatic hydrocarbon group) bonded to the nitrogen atom of (meth)acrylamide; wherein - contained in the hydrocarbon group CH ₂ - may be substituted with -CO-, and the hydrogen atom contained in the hydrocarbon group may be substituted with a hydroxyl group), etc. In addition, when the nitrogen atom of (meth)acrylamide is substituted by two or more groups (the hydrocarbon group), these groups may be bonded to each other to form a ring containing a nitrogen atom.

The number of carbon atoms of the hydrocarbon group (preferably an aliphatic hydrocarbon group) substituted on the nitrogen atom contained in the amide bond is preferably 1 or more, and preferably 10 or less, and more preferably 6 or less.

As the (meth)acrylamide monomer, one type or two or more types may be used. The (meth)acrylamide monomer can be any one of (meth)acrylamide, N-1 substituted (meth)acrylamide, and N,N-2 substituted (meth)acrylamide. .

As the (meth)acrylamide monomer, one or two or more kinds can be used, for example, (meth)acrylamide; N-isopropyl(meth)acrylamide, N-(meth)acrylamide, 1,1-Dimethyl-3-oxobutyl)acrylamide, N-hydroxymethyl(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butyl N-1 substituted (meth)acrylamide compounds such as oxymethyl(meth)acrylamide, N-(2-hydroxymethyl)acrylamide, N-(2-hydroxyethyl)acrylamide, etc. ; N-(meth)acrylylmorpholine, N-(meth)acrylylpyridone, N-(meth)acrylylpyridinone, N-(meth)acrylylpyrrolidine, N-(meth)acrylyl-4-piridinone, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N- Diisopropyl(meth)acrylamide, N,N-methylenebis(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, etc. N-2 Substituted (meth)acrylamide compounds, etc.

Among them, the (meth)acrylamide monomer preferably contains a monomer represented by formula (1).

[Chemical 1] [In formula (1), R ¹ represents a hydrogen atom or a methyl group; R ² and R ³ each independently represent a hydrogen atom or a hydrocarbon group with 1 to 20 carbon atoms. -CH ₂ - contained in the hydrocarbon group can be Substituted as -CO- or -O-, the hydrogen atom contained in the hydrocarbon group may be substituted with a hydroxyl group, and R ² and R ³ may be bonded to each other to form a ring containing nitrogen atoms]

The hydrocarbon groups represented by R ² and R ³ may be one type or two or more types, for example, linear or branched chain saturated aliphatic hydrocarbon groups; linear or branched chain unsaturated aliphatic groups; Family hydrocarbon groups, etc.

The (meth)acrylamide monomer is also preferably a (meth)acrylamide monomer in which both R ² and R ³ are the hydrocarbon groups. When the (meth)acrylamide monomer in which both R ² and R ³ are the hydrocarbon group is included, the content rate of units derived from the monomer is preferably in the acrylic polymer (A). It is 0.2 mass % or more, more preferably 0.5 mass % or more, and preferably 20 mass % or less, more preferably 15 mass % or less.

In the nitrogen-containing monomer (a2), the content rate of units derived from the acrylamide monomer is preferably 30 mass% or more, more preferably 60 mass% or more, further preferably 75 mass% or more, and the upper limit is 100% by mass.

Examples of the (meth)acrylate compound having a functional group containing a nitrogen atom (for example, an amino group, a 1-substituted amino group, a 2-substituted amino group, a nitrile group, etc.) include: (meth)acrylonitrile, ( Tert-butylaminoethyl methacrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc. Examples of the (meth)acrylate compound having the functional group containing a nitrogen atom include the functional group containing a nitrogen atom and a (meth)acrylic acid oxygen group via a single bond or a carbon number of 1 to 10 ( Preferred are compounds in which hydrocarbon groups (preferably alkyl groups) having 1 to 5 carbon atoms are bonded.

The nitrogen-containing monomer (a2) preferably contains a nitrogen-containing monomer having a hydroxyl group. The nitrogen-containing monomer having a hydroxyl group is preferably a (meth)acrylamide monomer having a hydroxyl group, and more preferably, in the formula (1), at least one of R ² and R ³ is a hydrocarbon group, and The hydrogen atom contained in the hydrocarbon group is substituted with a monomer of hydroxyl group.

The content rate of the nitrogen-containing monomer having a hydroxyl group in the nitrogen-containing monomer (a2) is preferably 50 mass% or more, more preferably 60 mass% or more, further preferably 65 mass% or more, and preferably 100 Mass% or less, more preferably 95 mass% or less, still more preferably 90 mass% or less.

In the acrylic polymer, the content of units derived from the nitrogen-containing monomer (a2) is preferably 2 mass% or more, more preferably 2.5 mass% or more, and preferably 20 mass% or less, more preferably 15 mass% or less.

The oxygen-alkylene chain-containing monomer (a3) is a monomer having an oxygen-alkylene unit and a polymerizable double bond in the molecule. The number of carbon atoms in the oxyalkylene unit is preferably 2 or more, and preferably 5 or less, more preferably 4 or less, further preferably 3 or less, and particularly preferably 2. As the monomer containing an oxygen alkylene chain, alkoxy polyalkylene glycol (meth)acrylate is preferred. Examples of the alkoxy group in the alkoxy polyalkylene glycol (meth)acrylate include: methoxy group, ethoxy group, propoxy group, etc. having 1 to 5 carbon atoms (preferably 1 to 3). of alkoxy.

As the oxygen alkylene chain-containing monomer (a3), one type or two or more types may be used, and examples thereof include methoxyethylene glycol methacrylate and methoxyethylene glycol acrylate.

The content rate of alkoxy polyalkylene glycol (meth)acrylate in the oxygen alkylene chain-containing monomer (a3) is 0 mass % or more, preferably 10 mass % or more, and more preferably 30 mass % % or more and 100 mass% or less, preferably 90 mass% or less, more preferably 80 mass% or less.

The repeating number of the oxygen alkylene unit in the oxygen alkylene chain-containing monomer (a3) is preferably 2 or more, more preferably 4 or more, further preferably 5 or more, and preferably 100 or less, more preferably 30 or less, more preferably 20 or less.

In the acrylic polymer (A), the content rate of units derived from the oxygen alkylene chain-containing monomer (a3) is preferably 0.5 mass % or more, more preferably 1.0 mass % or more, and still more preferably 1.5 Mass% or more, and preferably 30 mass% or less, more preferably 20 mass% or less, still more preferably 15 mass% or less.

The acrylic polymer (A) may also have a monomer (a3) derived from the (meth)acrylic acid alkyl ester (a1), the nitrogen-containing monomer (a2), and the oxygen-containing alkylene chain. ) other than the units of singletons (a4).

As the other monomer (a4), one or two or more types can be used, and examples thereof include: (meth)acrylic acid, (meth)carboxyethyl acrylate, (meth)carboxypentyl acrylate, (meth)acrylic acid ) Unsaturated monocarboxylic acids such as β-carboxyethyl acrylate; (meth)acrylic acid monomers with hydroxyl groups; (meth)acrylic acid monomers containing epoxy rings such as glycidyl (meth)acrylate; ( Alicyclic (meth)acrylic acid monomers such as cyclohexyl methacrylate; styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylvinylbenzene, α- Methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-hydroxystyrene and other aromatic vinyl monomers Amounts; monomers with two or more vinyl groups, etc.

Examples of the (meth)acrylic acid monomer having a hydroxyl group include compounds in which a hydroxyl group is bonded to the alkyl group of alkyl (meth)acrylate; polyalkylene glycol (meth)acrylate; and the like. , is preferably a compound in which a hydroxyl group is bonded to the alkyl group of (meth)acrylic acid alkyl ester, and more preferably is a compound in which a hydroxyl group is bonded to the terminal end of the alkyl group of (meth)acrylic acid alkyl ester.

The number of hydroxyl groups contained in the (meth)acrylic acid monomer having a hydroxyl group is preferably one. In addition, the (meth)acrylic acid monomer having a hydroxyl group is preferably an acrylic acid monomer having a hydroxyl group.

Examples of the alkyl acrylate include the same compounds as those exemplified as the alkyl (meth)acrylate (a1).

As the (meth)acrylic acid monomer having a hydroxyl group, one or two or more types can be used. Examples thereof include: (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 2-hydroxypropyl. (Meth)acrylic acid hydroxyalkanes such as 2-hydroxybutyl methacrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, etc. ester; polyethylene glycol (meth)acrylate, etc.

In the acrylic polymer (A), the content rate of units derived from the (meth)acrylic acid monomer having a hydroxyl group is preferably 0.01 mass % or more, more preferably 0.02 mass % or more, and still more preferably 0.03 mass %. % or more, and preferably 15 mass% or less, more preferably 12 mass% or less, still more preferably 10 mass% or less.

In the acrylic polymer (A), the content rate of units derived from other monomers (a4) is 0 mass % or more, more preferably more than 0 mass %, further preferably 0.01 mass % or more, and preferably 20 mass %. The content is % by mass or less, more preferably 10 % by mass or less, and even more preferably 5 % by mass or less.

The weight average molecular weight of the acrylic polymer (A) is preferably 100,000 or more, more preferably 200,000 or more, further preferably 300,000 or more, and preferably 2 million or less, more preferably 1.8 million or less, further preferably 1.50 Less than 10,000.

In this specification, the number average molecular weight and weight average molecular weight of the acrylic polymer (A) represent conversions measured using gel permeation chromatography (GPC) using polystyrene as a standard sample. value.

In the adhesive composition of the present invention, the content of the acrylic polymer (A) in non-volatile components is preferably 15 mass% or more, more preferably 20 mass% or more, and still more preferably 25 mass% or more, and Preferably it is 100 mass % or less.

In this specification, the non-volatile component of the adhesive composition refers to the portion after removal of the optional solvent component contained in the adhesive composition.

The acrylic polymer (A) can be prepared by making the (meth)acrylic acid alkyl ester (a1), the nitrogen-containing monomer (a2), and the monomer containing an oxygen alkylene chain in the presence of a polymerization initiator. (a3) and other monomers (a4) used as necessary are copolymerized and produced.

As the polymerization initiator, for example, one or more than two kinds of thermal polymerization initiators can be used. Examples include peroxide initiators such as benzoyl peroxide and lauryl peroxide; azobisisobutyronitrile. Azo starter, etc.

The adhesive composition of the present invention includes a cross-linking agent (B) including a metal chelate cross-linking agent (b1).

Examples of the metal chelate crosslinking agent (b1) include acetylene and acetyl coordinated to polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. A compound made of ethyl acetate.

The metal chelate cross-linking agent (b1) can also be dissolved in an organic solvent in advance and used in the form of a metal chelate cross-linking agent (b1) solution. Examples of the organic solvent include the same compounds as the solvent (D) described below. When the metal chelate crosslinking agent (b1) is dissolved in an organic solvent in advance, its concentration is preferably 1 to 10 mass%, for example.

The content rate of the metal chelate cross-linking agent (b1) in the cross-linking agent (B) is preferably 0.5 mass % or more, more preferably 1 mass % or more, further preferably 2 mass % or more, and preferably It is 70 mass % or less, more preferably 50 mass % or less, still more preferably 40 mass % or less.

In addition to the metal chelate cross-linking agent (b1), the cross-linking agent (B) may also include other cross-linking agents (b2). As the other cross-linking agent (b2), one or two or more kinds can be used. For example, isocyanate cross-linking agent, epoxy cross-linking agent, melamine cross-linking agent, aziridine cross-linking agent, polyvalent metal Salt cross-linking agent, ketone-hydrazine cross-linking agent, oxazoline cross-linking agent, carbodiimide cross-linking agent, silane cross-linking agent, glycidyl (alkoxy) epoxy silane cross-linking agent, etc.

As the other cross-linking agent (b2), preferably isocyanate cross-linking agent, epoxy cross-linking agent, melamine cross-linking agent, oxazoline cross-linking agent, carbodiimide cross-linking agent, glycidyl (alkoxy base) epoxy silane cross-linking agent, more preferably isocyanate cross-linking agent, epoxy cross-linking agent, melamine cross-linking agent, carbodiimide cross-linking agent, especially isocyanate cross-linking agent.

The content rate of the isocyanate cross-linking agent in the cross-linking agent (B) is preferably 30 mass % or more, more preferably 50 mass % or more, further preferably 70 mass % or more, and preferably 100 mass % or less, More preferably, it is 98 mass % or less.

The content rate of the cross-linking agent (B) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, still more preferably 3 parts by mass or more, based on 100 parts by mass of the acrylic polymer (A), and preferably It is 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less.

The adhesive composition of the present invention contains a plasticizer (C). The plasticizer (C) contains an esterification product of a compound (c1) having a hydroxyl group and a compound (c2) having an acid group.

The compound (c1) having a hydroxyl group is a compound having one or more hydroxyl groups per molecule. In the compound (c1) having a hydroxyl group, the number of hydroxyl groups is preferably one or more per molecule, and preferably The number is 6 or less, more preferably 4 or less, still more preferably 2 or less.

The compound (c1) having a hydroxyl group may be a chain compound such as a straight chain or a branched chain, or a cyclic compound such as an alicyclic or aromatic ring, or a combination of a chain group and a cyclic group. The compound is preferably a chain compound.

The compound (c1) having a hydroxyl group is preferably a compound represented by the following formula (2) or formula (3).

[Chemicalization 2]

[In formula (2), R ⁴ represents a monovalent chain hydrocarbon group having 2 to 18 carbon atoms or one or more -CH ₂ - contained in a monovalent hydrocarbon group having 5 to 50 carbon atoms substituted with -O- In the formula (3), R ⁵ represents a divalent chain hydrocarbon group with 2 to 18 carbon atoms or one or more -CH ₂ - contained in a divalent hydrocarbon group with 5 to 65 carbon atoms substituted with - O-base]

Examples of the chain hydrocarbon group represented by R ⁴ include: ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, n-pentyl, isopentyl, sec-pentyl Base, tert-pentyl, n-hexyl, n-heptyl, 2-heptyl, isoheptyl, sec-heptyl, tert-heptyl, n-octyl, isooctyl, sec-octyl, tert-octyl, 2-ethyl Hexyl, n-nonyl, isononyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl Alkyl groups such as alkyl groups may be linear or branched. The number of carbon atoms of the chain hydrocarbon group represented by R ⁴ is preferably 4 to 16, and more preferably 6 to 13.

Among the groups represented by R ⁴ , examples of groups in which one or more -CH ₂ -s contained in the monovalent chain hydrocarbon group are substituted with -O- include one or more oxygen extension groups having 2 to 10 carbon atoms. A base of alkyl units. The number of carbon atoms of the oxyalkylene unit is preferably 2 to 6, more preferably 2 to 4, and still more preferably 3 to 4. In the compound (c1) having a hydroxyl group, the oxyalkylene unit may be one type or two or more. For example, it may include an oxyalkylene unit having 2 carbon atoms and an oxyalkylene unit having 3 or more carbon atoms. Alkyl units both.

In the group represented by R ⁴ , in a group in which one or more -CH ₂ - contained in the monovalent chain hydrocarbon group is substituted with -O-, the total number of oxyalkylene units is preferably 1 or above, and preferably 20 or less, more preferably 15 or less.

Examples of the divalent chain hydrocarbon group represented by R ⁵ include: ethanediyl, propanediyl, butanediyl, pentanediyl, hexanediyl, heptanediyl, octanediyl, nonyl Alkanediyl groups such as alkanediyl and decanediyl may be linear or branched. The number of carbon atoms of the chain hydrocarbon group represented by R ⁵ is preferably 2 to 10, more preferably 2 to 6, and even more preferably 3 to 4.

Among the groups represented by R ⁵ , examples of groups in which one or more -CH ₂ -s contained in the divalent chain hydrocarbon group are substituted with -O- include one or more oxygen extension groups having 2 to 10 carbon atoms. A base of alkyl units. The number of carbon atoms of the oxyalkylene unit is preferably 2 to 6, more preferably 2 to 4, and still more preferably 3 to 4. In the compound (c1) having a hydroxyl group, the oxyalkylene unit may be one type or two or more. For example, it may include an oxyalkylene unit having 2 carbon atoms and an oxyalkylene unit having 3 or more carbon atoms. Alkyl units both.

In the group represented by R ⁵ in which one or more -CH ₂ - contained in the divalent chain hydrocarbon group is substituted with -O-, the total number of oxyalkylene units is preferably 2 or above, and preferably 20 or less, more preferably 15 or less.

The total content of the compound represented by the formula (2) or the formula (3) in the compound (c1) having a hydroxyl group is preferably 80 mass % or more, more preferably 90 mass % or more, and still more preferably It is 95 mass% or more, and the upper limit is 100 mass%.

Among the compounds (c1) having a hydroxyl group, examples of compounds having three or more hydroxyl groups per molecule include glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and the like.

The compound (c2) having an acid group is a compound having at least one acid group per molecule. In the compound (c2) having an acid group, the number of acid groups is preferably 1 per molecule. or above, and preferably 6 or less, more preferably 4 or less, still more preferably 3 or less, still more preferably 2 or less. Examples of the acid group include a carboxyl group, a phosphate group, a sulfonic acid group, and the like, and a carboxyl group is preferred.

The compound (c2) having an acid group may be a chain compound such as a linear chain or a branched chain, or a compound containing a ring structure such as an alicyclic ring or an aromatic ring. In addition to having an acid group, the compound (c2) having an acid group may also have other functional groups such as hydroxyl group, epoxy group, (meth)acrylyl group, etc., or may not have other functional groups.

The compound (c2) having an acid group is preferably a compound represented by the following formula (4) or formula (5).

[Chemical 3]

[In formula (4) and formula (5), R ⁶ represents a monovalent aliphatic hydrocarbon group having 4 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. The aliphatic hydrocarbon group represented by R ⁶ The hydrocarbon group may also have a hydroxyl group as a substituent; R ⁷ represents a divalent aliphatic hydrocarbon group having 4 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms; R ^a represents an acid group]

Examples of the aliphatic hydrocarbon group represented by R ⁶ include alkyl groups such as butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl. The aliphatic hydrocarbon group represented by R ⁶ may be linear or branched. The number of carbon atoms of the aliphatic hydrocarbon group represented by R ⁶ is preferably 4 to 16, and more preferably 4 to 10.

Examples of the aromatic hydrocarbon group represented by R ⁶ include monocyclic or polycyclic aromatic hydrocarbon groups such as phenyl, tolyl, and xylyl. The number of carbon atoms of the aromatic hydrocarbon group represented by R ⁶ is preferably 6 to 15, and more preferably 6 to 10.

R ⁶ is preferably a monovalent aliphatic hydrocarbon group having 4 to 10 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms.

Examples of the divalent aliphatic hydrocarbon group represented by R ⁷ include butanediyl, pentanediyl, hexanediyl, heptanediyl, octanediyl, nonanediyl, decanediyl, etc. alkanediyl. The divalent aliphatic hydrocarbon group represented by R ⁷ may be linear or branched. The number of carbon atoms of the divalent aliphatic hydrocarbon group represented by R ⁷ is preferably 4 to 16, and more preferably 4 to 10.

Examples of the divalent aromatic hydrocarbon group represented by R ⁷ include monocyclic or polycyclic divalent aromatic hydrocarbon groups such as phenylene group, tolynylene group, and xylylene group. The number of carbon atoms of the divalent aromatic hydrocarbon group represented by R ⁷ is preferably 6 to 15, and more preferably 6 to 10.

R ⁷ is preferably an aliphatic hydrocarbon group, preferably an aliphatic hydrocarbon group having 4 to 10 carbon atoms.

Examples of the acid group represented by R ^a include a carboxyl group, a phosphate group, a sulfonic acid group, and the like, and a carboxyl group is preferred.

The content rate of the compound represented by the formula (4) or the formula (5) in the compound (c2) having an acid group is preferably 80 mass% or more, more preferably 90 mass% or more, and still more preferably 95 mass%. % or more, the upper limit is 100 mass%.

Among the compounds (c2) having an acidic group, compounds having three or more acidic groups per molecule include: tricarboxylic acid; hydroxytricarboxylic acid such as citric acid; trimellitic acid, pyromellitic acid Formic acid and other aromatic polycarboxylic acids.

In the plasticizer (C), the content of the esterified product of the compound (c1) having a hydroxyl group and the compound (c2) having an acid group is preferably 80 mass% or more, more preferably 90 mass% or more, and further Preferably it is 95 mass % or more, and the upper limit is 100 mass %.

The number average molecular weight of the plasticizer (C) is 6,000 or less, preferably 3,000 or less, more preferably 2,000 or less, and the lower limit may be, for example, 100 or more or 150 or more.

The solubility parameter of the plasticizer (C) is 10 (cal/cm ³ ) ^1/2 or less, preferably 9.5 (cal/cm ³ ) ^1/2 or less, more preferably 9.0 (cal/cm ³ ) ^{1/ 2} or less, preferably 7.5 (cal/cm ³ ) ^1/2 or more, more preferably 8.0 (cal/cm ³ ) ^1/2 or more. The solubility parameter of the plasticizer (C) is a value calculated based on Small's equation.

The content of the plasticizer (C) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, based on 100 parts by mass of the acrylic polymer (A), and more preferably 1 part by mass or more. 30 parts by mass or less.

The adhesive composition of the present invention preferably contains solvent (D). As the solvent (D), one or two or more types can be used. For example, aromatic hydrocarbon solvents such as toluene and xylene; ester solvents such as ethyl acetate and butyl acetate; acetone, methyl ethyl ketone, etc. Ketone solvent; aliphatic hydrocarbon solvent such as hexane, etc. Among these, it is preferable to include an ester solvent.

The content of the ester solvent in the solvent (D) is preferably 50 mass% or more, more preferably 80 mass% or more, further preferably 90 mass% or more, and preferably 100 mass% or less.

The content rate of the solvent (D) in the adhesive composition is preferably 10 mass% or more, more preferably 30 mass% or more, further preferably 50 mass% or more, and preferably 90 mass% or less, more preferably The content is 70% by mass or less, and more preferably 65% by mass or less.

In the adhesive composition of the present invention, in order to maintain low yellowing, it is preferable to reduce the content of the adhesion-imparting resin. It is preferably less than 10 parts by mass, and more preferably 8 parts by mass or less relative to 100 parts by mass of the acrylic polymer. It is more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, and preferably 0 parts by mass. By adopting a structure that uses an acrylic polymer (A) with a specific composition and weight average molecular weight and does not contain an adhesion-imparting resin, it is possible to maintain low yellowing of the adhesive layer and maintain low yellowness even under high temperature/high humidity conditions. Adhesion, inhibits contamination of the surface of the adherend after it peels off.

The adhesive composition of the present invention may also include alkali (ammonia, etc.) or acid for adjusting the pH value; foaming agent; softener; antioxidant; glass or plastic fiber-balloon-bead-metal powder and other fillers Agents; pigments, dyes and other colorants; pH adjusters; film forming auxiliaries; leveling agents; tackifiers; hydrophobic agents; defoaming agents; acid catalysts; acid generators, etc. as additives.

An adhesive layer can be formed by applying the adhesive composition on a support and drying it. The support may be any base material such as a release sheet or an adhesive sheet.

As the coating method, methods such as a blade coater, a reverse coater, a die coater, a lip die coater, a slit die coater, a gravure coater, a curtain coater, etc. can be used.

The thickness of the adhesive layer is preferably 1 μm or more, more preferably 3 μm or more, further preferably 5 μm or more, and preferably 100 μm or less, more preferably 70 μm or less, still more preferably 50 μm or less.

The adhesive sheet or adhesive tape of the present invention has the adhesive layer and the base material. The base material may be in any shape such as film, sheet, strip, plate, or three-dimensional shape. Examples of the material of the base include polyester resin, polypropylene resin, polyethylene resin, and polyethylene resin. Plastics such as amine resin, vinyl chloride resin, and urethane resin; rubber; non-woven fabrics; metal foil; paper, etc. are preferably plastics, and more preferably vinyl chloride resins. In addition, the base material may be a base material with a smooth surface, or a base material with an uneven surface such as a fibrous base material or a foam base material.

The thickness of the base material is preferably 0.1 μm or more and preferably 1,000 μm or less. [Example]

Hereinafter, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to the following Examples, and can of course be implemented with appropriate modifications within the scope suitable for the above-mentioned and later-described gist. These are all included in the technical scope of the present invention.

[Synthesis example 1] ＜Synthesis of acrylic polymer (A1)＞ Into a reaction container including a stirrer, a reflux cooling pipe, a nitrogen introduction pipe, and a thermometer, 830 parts by mass of n-butyl acrylate (hereinafter, sometimes referred to as "BA") and methyl acrylate (hereinafter, sometimes referred to as "MA") were placed ") 50 parts by mass, 50 parts by mass of hydroxyethylacrylamide (hereinafter, sometimes referred to as "HEAA"), 10 parts by mass of acrylamide (hereinafter, sometimes referred to as "AM"), NK ester ) AM-90G (manufactured by Shin-Nakamura Chemical Co., Ltd.) 10 parts by mass, NK ester M-90G (manufactured by Shin-Nakamura Chemical Co., Ltd.) 40 parts by mass, hydroxyethyl acrylate (below, sometimes (called "HEA") 10 parts by mass and 1000 parts by mass of ethyl acetate, and while stirring, the temperature was raised to 65°C while blowing nitrogen gas. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 65°C for 10 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile content of 50% by mass, a viscosity of 240,000 mPa·s, and a weight average molecular weight of 900,000. Acrylic polymer (A1).

[Synthesis example 2] ＜Synthesis of acrylic polymer (A2)＞ Into a reaction container including a stirrer, reflux cooling tube, nitrogen introduction tube, and thermometer, 400 parts by mass of n-butyl acrylate, 310 parts by mass of 2-ethylhexyl acrylate (hereinafter, sometimes referred to as "2EHA"), and acrylic acid 100 parts by mass of methyl ester, 100 parts by mass of hydroxyethylacrylamide, 20 parts by mass of dimethylacrylamide (hereinafter, sometimes referred to as "DMAA"), NK ester AM-130G (Shin Nakamura Chemical 40 parts by mass of Industrial Co., Ltd.), 30 parts by mass of 4-hydroxybutyl acrylate (hereinafter sometimes referred to as "4HBA"), and 1000 parts by mass of ethyl acetate were stirred and heated to 70°C while blowing in nitrogen. ℃. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 70°C for 8 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile content of 50% by mass, a viscosity of 120,000 mPa·s, and a weight average molecular weight of 440,000. Acrylic polymer (A2).

[Synthesis example 3] ＜Synthesis of acrylic polymer (A3)＞ Into a reaction vessel including a mixer, a reflux cooling pipe, a nitrogen introduction pipe, and a thermometer, 735 parts by mass of n-butyl acrylate, 100 parts by mass of 2-ethylhexyl acrylate, 50 parts by mass of methyl acrylate, and acryloyl morpholine (Hereinafter, sometimes referred to as "ACMO") 20 parts by mass, hydroxyethylacrylamide 50 parts by mass, NK ester (NK ester) AM-90G 20 parts by mass, NK ester (NK ester) M-90G 20 parts by mass , 5 parts by mass of hydroxyethyl methacrylate (hereinafter, sometimes referred to as "HEMA") and 1000 parts by mass of ethyl acetate were stirred and heated to 65°C while blowing nitrogen gas. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 65°C for 10 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile content of 50% by mass, a viscosity of 160,000 mPa·s, and a weight-average molecular weight of 1.05 million. Acrylic polymer (A3).

[Synthesis Example 4] ＜Synthesis of acrylic polymer (A4)＞ Into a reaction container including a mixer, a reflux cooling pipe, a nitrogen introduction pipe, and a thermometer, 825 parts by mass of n-butyl acrylate, 50 parts by mass of methyl acrylate, 20 parts by mass of acryloylmorpholine, and 50 parts by mass of dimethylacrylamide 50 parts by mass of NK ester M-230G (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 5 parts by mass of 4-hydroxybutyl acrylate, and 1000 parts by mass of ethyl acetate were blown in while stirring. The nitrogen side was heated to 70°C. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 70°C for 8 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile content of 50% by mass, a viscosity of 150,000 mPa·s, and a weight-average molecular weight of 650,000. Acrylic polymer (A4).

[Synthesis Example 5] ＜Synthesis of acrylic polymer (A5)＞ Into a reaction container including a mixer, a reflux cooling tube, a nitrogen introduction tube, and a thermometer, 710 parts by mass of 2-ethylhexyl acrylate, 150 parts by mass of methyl acrylate, 50 parts by mass of hydroxyethyl acrylamide, and NK ester ( NK ester) AM-130G 20 parts by mass, NK ester (NK ester) M-90G 20 parts by mass, 50 parts by mass of hydroxyethyl acrylate, and 1000 parts by mass of ethyl acetate were stirred and heated to 65 while blowing in nitrogen. ℃. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 65°C for 10 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile component of 50% by mass, a viscosity of 420,000 mPa·s, and a weight-average molecular weight of 1.15 million. Acrylic polymer (A5).

[Synthesis example 6] ＜Synthesis of acrylic polymer (A6)＞ Into a reaction vessel including a mixer, a reflux cooling tube, a nitrogen introduction tube, and a thermometer, 850 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of acryloyl morpholine, 40 parts by mass of acrylamide, and NK ester (NK ester) AM-90G 50 parts by mass, 10 parts by mass of hydroxyethyl methacrylate, 30 parts by mass of acrylic acid (hereinafter sometimes referred to as "AA"), and 1000 parts by mass of ethyl acetate, while stirring, blowing in nitrogen Heat up to 70°C on one side. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 70°C for 8 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile content of 50% by mass, a viscosity of 125,000 mPa·s, and a weight-average molecular weight of 580,000. Acrylic polymer (A6).

[Synthesis Example 7] ＜Synthesis of acrylic polymer (A7)＞ Into a reaction vessel including a mixer, a reflux cooling pipe, a nitrogen introduction pipe, and a thermometer, 270 parts by mass of n-butyl acrylate, 400 parts by mass of 2-ethylhexyl acrylate, 50 parts by mass of hydroxyethyl acrylamide, and dimethyl 20 parts by mass of acrylamide, 120 parts by mass of NK ester M-90G, 40 parts by mass of 4-hydroxybutyl acrylate, 100 parts by mass of cyclohexyl acrylate (hereinafter, sometimes referred to as "CHMA"), 1000 parts by mass of ethyl acetate was heated to 70°C while blowing nitrogen gas with stirring. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 65°C for 10 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile content of 50% by mass, a viscosity of 210,000 mPa·s, and a weight-average molecular weight of 1.25 million. Acrylic polymer (A7).

[Synthesis example 8] <Synthesis of acrylic polymer (A1')> Into a reaction container including a mixer, a reflux cooling pipe, a nitrogen introduction pipe, and a thermometer, 300 parts by mass of n-butyl acrylate, 350 parts by mass of 2-ethylhexyl acrylate, 150 parts by mass of methyl acrylate, and dimethacrylamide 100 parts by mass of amine, 100 parts by mass of hydroxyethyl acrylate, and 1000 parts by mass of ethyl acetate were heated to 70° C. while blowing nitrogen gas while stirring. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 70°C for 8 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile content of 50% by mass, a viscosity of 110,000 mPa·s, and a weight-average molecular weight of 550,000. Compare acrylic polymer (A1').

[Synthesis Example 9] <Synthesis of acrylic polymer (A2')> Into a reaction container including a stirrer, a reflux cooling tube, a nitrogen introduction tube, and a thermometer, 790 parts by mass of 2-ethylhexyl acrylate, 150 parts by mass of NK ester AM-90G, and 50 parts by mass of hydroxyethyl methacrylate were placed. parts by mass, 10 parts by mass of acrylic acid, and 1000 parts by mass of ethyl acetate, and the temperature was raised to 70° C. while blowing nitrogen gas while stirring. One hour later, 10 parts by mass of a 2,2'-azobis(2-methylbutyronitrile) solution dissolved in ethyl acetate in advance (solid content: 5 mass%) was added. Thereafter, after holding at 70°C for 8 hours with stirring, the contents were cooled and filtered through a 200-mesh metal mesh to obtain a non-volatile content of 50% by mass, a viscosity of 110,000 mPa·s, and a weight-average molecular weight of 520,000. Compare acrylic polymer (A2').

[Example 1] With respect to 100 parts by mass of the acrylic polymer (A1) obtained in Synthesis Example 1, 3.5 parts by mass of diisononyl adipate and an aluminum acetyl acetonate solution (solid content 5% by mass) were stirred and mixed so as to become uniform. ) 5.0 parts by mass, isocyanate cross-linking agent (Finetack hardener DN; manufactured by DIC Co., Ltd.) 2.5 parts by mass, hindered phenol antioxidant (Irganox 1010; Japan An acrylic adhesive composition was obtained by using 1 part by mass of BASF Japan (manufactured by BASF Japan Co., Ltd.) and 260 parts by mass of ethyl acetate.

[Example 2 to Example 10, Comparative Example 1 to Comparative Example 6] An acrylic adhesive composition was obtained in the same manner as in Example 1, except that the types and amounts of the acrylic resin (A), cross-linking agent (B), and plasticizer (C) were changed. Each resin is shown in Table 1, each cross-linking agent is shown in Table 2, and the composition of each plasticizer is shown in Table 1. The acrylic resin and plasticizer used in each acrylic adhesive composition The types and amounts of cross-linking agents are shown in Tables 4 to 6.

[Processing method of adhesive film] The film obtained in Examples and Comparative Examples was applied to the surface of a 50 μm-thick polyethylene terephthalate film (release PET50) with a release treatment so that the film thickness after solvent drying was 5 μm. The acrylic adhesive composition was used to evaporate the solvent in a dryer at 80°C for 3 minutes, and then the PET 10 μm film was bonded.

[Measurement method of adhesive strength] The adhesive film produced by the above method was cut into a width of 25 mm, and the resultant article was used as a test piece. Set the adherend as a glass plate and attach it to the adherend using a 2 kg roller × 1 reciprocation. After 1 hour of attachment, the 180-degree peel strength was measured at a peeling speed of 300 mm/min in an environment of 23°C and 50% RH, and was set as the adhesive strength.

[Measurement method of adhesive strength after heat resistance] In the same manner as the method for measuring the adhesive force, a test piece is attached to the adherend and left to stand for 1 hour. Then, it was left to stand in an environment of 150° C. RH for 1 hour, and immediately thereafter, it was left to stand in an environment of 23° C. and 50% RH for 30 minutes. After repeating the above operation five times, it was left in an environment of 23°C and 50% RH for 30 minutes. After that, the 180-degree peel strength was measured at a peeling speed of 300 mm/min, and was regarded as the adhesive strength after heat resistance.

[Method for evaluation of adherend contamination resistance under moist and heat-resistant conditions] In the same manner as the above-mentioned measurement method of adhesive force, a test piece is attached to the adherend. Thereafter, it was left in an environment of 65° C. and 90% RH for 3 days, and then taken out. After leaving it in an environment of 23°C and 50% RH for 24 hours, peel off the test piece, and irradiate the peeled adherend surface (the attached part) with light-emitting diode (LED) light to confirm Whether there is contamination on the surface of the adherend is used as an evaluation of contamination resistance. 〇：No pollution △: No adhesive remains on the surface of the adherend, but there are white traces ×: Adhesive remains on the surface of the adherend

[Evaluation method for adherend contamination under heat-resistant conditions] In the same manner as the above-mentioned measurement method of adhesive force, a test piece is attached to the adherend. Thereafter, it was left to stand in an environment of 150° C. RH for 1 hour, and immediately thereafter it was left to stand in an environment of 23° C. and 50% RH for 30 minutes. After repeating the above operation 5 times, leave it in an environment of 23°C and 50% RH for 30 minutes, peel off the test piece, and irradiate the peeled adherend surface (the adhered part) with LED light to confirm Whether there is contamination on the surface of the adherend is used as an evaluation of contamination resistance. 〇：No pollution △: No adhesive remains on the surface of the adherend, but there are white traces ×: Adhesive remains on the surface of the adherend

[Evaluation method of water contact angle] Measure the water contact angle A of the adherend without a test piece attached or exposed to temperature conditions. Then, in the same manner as the above-mentioned method for measuring the adhesive force, a test piece is attached to the adherend. Thereafter, it was left to stand in an environment of 150° C. RH for 1 hour, and immediately thereafter it was left to stand in an environment of 23° C. and 50% RH for 30 minutes. After repeating the above operation five times, the test piece was peeled off after leaving it in an environment of 23°C and 50% RH for 30 minutes, and the water contact angle B of the peeled adherend surface (the portion where the adhesion was performed) was measured. The change in water contact angle is calculated from the following (Equation 1). (Formula 1) Contact angle B-contact angle A ◎: The change in water contact angle is less than 10° ○: Change in water contact angle is 10° or more and less than 20° △: The change in water contact angle is 20° or more and less than 30° ×: Change in water contact angle is 30° or more

[Table 1] Resin (A1) (A2) (A3) (A4) (A5) (A6) (A7) (A1') (A2') (a1) BA 83 40 73.5 82.5 27 30 2EHA 31 10 71 85 40 35 79 MA 5 10 5 5 15 15 (a2) ACMO 2 2 2 HEAA 5 10 5 5 5 DMAA 2 5 2 10 AM 1 4 (a3) AM-90G 1 2 5 15 AM-130G 4 2 M-90G 4 2 2 12 M-230G 5 (a4) HEA 1 5 10 4HBA 3 0.5 4 HEMA 0.5 1 5 CHA 10 AA 3 1

[Table 2] Kind Type manufacturer Trade name/(chemical name) Solid content i Metal chelates (b1) - (Triacetyl acetonate aluminum) 5% ii Isocyanate (b2) DIC Co., Ltd. finetack hardener DN 75% iii Isocyanate (b2) DIC Co., Ltd. burnock DN950 75% iv Isocyanate (b2) DIC Co., Ltd. burnock DN980 75% v Isocyanate (b2) DIC Co., Ltd. Finetack hardener D-100K 100% vi Isocyanate (b2) DIC Co., Ltd. Finetack hardener D-40 40% vii Isocyanate (b2) Asahi Kasei Co., Ltd. duranate 24A-100 100% viii Epoxy DIC Co., Ltd. Finetack hardener EX-50 50%

[table 3] Plasticizer Common name Compounds with hydroxyl groups (c1) Compounds with acidic groups (c2) number average molecular weight SP value I Diisononyl adipate Isononyl alcohol Adipic acid 399 8.5 II Isopropyl myristate Isopropyl alcohol Myristic acid 270 8.2 III - Polyethylene glycol #300 2-Ethylhexanoic acid 617 8.4 IV - 1,3-butanediol Adipic acid 2,300 9.3 1,4-butanediol 2-Ethylhexanol V - Isononyl alcohol Adipic acid 1,000 8.9 polypropylene glycol polyethylene glycol VI - Polyethylene glycol #600 2-Ethylhexanoic acid 850 8.4 VII Diisopropyl benzoate propylene glycol benzoic acid 284 10.1 VIII - 1,2-propanediol sebacic acid 8,000 9.1

[Table 4] Example 1 Example 2 Example 3 Example 4 Example 5 Acrylic polymer (A) (A1) (A2) (A3) (A4) (A5) (parts by mass) 100 100 100 100 100 Cross-linking agent (B) Metal chelates (b1) i i i i i (parts by mass) 5.0 10.0 12.5 45.0 25.0 Isocyanate (b2) ii iii ii ii iv (parts by mass) 2.5 3.5 4.5 7.0 4.0 Epoxy - - - - - (parts by mass) Plasticizer (C) I II III IV V (parts by mass) 3.50 1.50 2.50 17.50 10.00 Adhesion [gf/25mm] 40 20 twenty two 40 10 Heat-resistant adhesion [gf/25 mm] 90 85 81 84 40 water contact angle [°] ○ ○ ○ △ ○ Adherent contamination resistance (humidity and heat resistance) ○ ○ ○ ○ ○ Adherent contamination resistance (heat resistance) ○ ○ ○ △ ○

[table 5] Example 6 Example 7 Example 8 Example 9 Example 10 Acrylic polymer (A) (A1) (A6) (A3) (A7) (A6) (parts by mass) 100 100 100 100 100 Cross-linking agent (B) Metal chelates (b1) i i i i i (parts by mass) 12.0 3.0 9.0 13.5 5.0 Isocyanate (b2) v vi vii ii - (parts by mass) 2.7 13.3 1.5 3.5 - Epoxy - - - viii viii (parts by mass) 0.4 3 Plasticizer (C) I I VI VI I (parts by mass) 5.00 4.00 8.00 4.00 4.50 Adhesion [gf/25mm] 9 11 9 11 37 Heat-resistant adhesion [gf/25mm] 35 89 19 98 99 water contact angle [°] ◎ ◎ ◎ ○ △ Adherent contamination resistance (humidity and heat resistance) ○ ○ ○ △ △ Adherent contamination resistance (heat resistance) ○ △ ○ △ △

[Table 6] Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Acrylic polymer (A) (A1) (A2) (A3) (A4) (A1') (A2') (parts by mass) 100 100 100 100 100 100 Cross-linking agent (B) Metal chelates (b1) - i i i i i (parts by mass) 5.0 5.0 5.0 5.0 5.0 Isocyanate (b2) ii ii vii v v iii (parts by mass) 2.5 3.5 2.5 4.2 1.8 4.0 Epoxy - - - - - - (parts by mass) Plasticizer (C) I - VII VIII VI VI (parts by mass) 6.00 - 6.00 6.00 6.00 6.00 Adhesion [gf/25 mm] 69 166 53 62 twenty four 26 Heat-resistant adhesion [gf/25mm] 174 218 126 151 80 71 water contact angle [°] × × ○ △ △ ○ Adherent contamination resistance (humidity and heat resistance) ○ × △ ○ × × Adherent contamination resistance (heat resistance) ○ × × ○ × ×

without.

without.

without.

Claims (8)

An adhesive composition comprising an acrylic polymer (A), a cross-linking agent (B) and a plasticizer (C), the acrylic polymer (A) comprising an alkyl (meth)acrylate (a1) units derived from the nitrogen-containing monomer (a2), and units derived from the oxygen-containing alkylene chain-containing monomer (a3), and the content rate of the units derived from the nitrogen-containing monomer (a2) is as follows: 2 mass % or more in the acrylic polymer (A), the cross-linking agent (B) includes a metal chelate cross-linking agent (b1), the plasticizer (C) includes a compound having a hydroxyl group (c1) and The esterification product of the compound (c2) having an acid group, the solubility parameter value (Smore's formula) of the plasticizer (C) is 10 (cal/cm ³ ) ^1/2 or less, and the plasticizer (C) ) has a number average molecular weight of 6,000 or less. The adhesive composition according to claim 1, wherein the content of the plasticizer (C) is 1 part by mass or more and 40 parts by mass or less based on 100 parts by mass of the acrylic polymer (A). The adhesive composition according to claim 1 or claim 2, wherein the cross-linking agent (B) further includes an isocyanate cross-linking agent (b2). The adhesive composition according to claim 1 or claim 2, wherein the content of the metal chelate cross-linking agent (b1) is 0.1 parts by mass or more and 5 parts per 100 parts by mass of the acrylic polymer (A). parts by mass or less. The adhesive composition according to claim 3, wherein the content of the metal chelate cross-linking agent (b1) is 0.1 to 5 parts by mass relative to 100 parts by mass of the acrylic polymer (A). The adhesive composition according to claim 3, wherein the content of the isocyanate cross-linking agent (b2) is 1 part by mass or more and 15 parts by mass or less based on 100 parts by mass of the acrylic polymer (A). An adhesive layer formed from the adhesive composition according to any one of claims 1 to 6. An adhesive film having an adhesive layer as described in claim 7.