KR20230167428A - Subject matter for adhesives, adhesive compositions and adhesive films - Google Patents

Abstract

The purpose of the present disclosure is to provide a pressure-sensitive adhesive composition with excellent adhesiveness.
The adhesive composition according to the present disclosure includes 2-ethylhexyl acrylate (a1) and branched alkyl (meth)acrylate (a2) having a branched alkyl group having 4 to 10 carbon atoms other than 2-ethylhexyl acrylate (a1). , a copolymer (A) containing as a constituent monomer at least one type of monomer selected from the group consisting of straight-chain alkyl (meth)acrylate (a3) having a straight-chain alkyl group having 1 to 4 carbon atoms and nitrogen atom-containing monomer (a4) ) contains. The carboxyl group concentration of the copolymer (A) is 0.08 mol/kg or less, the hydroxyl group concentration is 0.05 mol/kg or less, and the copolymer (A) derived from 2-ethylhexyl acrylate (a1) and branched alkyl (meth)acrylate (a2) Class 3 carbon concentration is 1.5 mol/kg or more and 5.0 mol/kg or less.

Description

Subject matter for adhesives, adhesive compositions and adhesive films

The present disclosure relates to a base material for an adhesive, an adhesive composition, and an adhesive film.

As acrylic adhesives, (co)polymers containing specific alkyl (meth)acrylates as essential structural units are being developed (for example, patent document 1).

Japanese Patent Publication No. 2004-143420

The purpose of the present disclosure is to provide an adhesive base material for producing an adhesive film with excellent adhesiveness, an adhesive composition containing this adhesive base material, and an adhesive film produced from this adhesive composition.

The base material (B) for an adhesive according to one aspect of the present disclosure includes 2-ethylhexyl acrylate (a1) and a branched alkyl group having 4 to 10 carbon atoms other than the 2-ethylhexyl acrylate (a1). At least one member selected from the group consisting of branched alkyl (meth)acrylate (a2) having a straight chain alkyl group having 1 to 4 carbon atoms (a3) and nitrogen atom-containing monomer (a4). It contains a copolymer (A) containing the monomers as constituent monomers. The carboxyl group concentration of the copolymer (A) is 0.08 mol/kg or less. The hydroxyl group concentration of the copolymer (A) is 0.05 mol/kg or less. The concentration of tertiary carbon derived from the 2-ethylhexyl acrylate (a1) and the branched alkyl (meth)acrylate (a2) of the copolymer (A) is 1.5 mol/kg or more and 5.0 mol/kg or less.

The adhesive composition according to one aspect of the present disclosure contains the adhesive base material (B) and polyfunctional (meth)acrylate (C).

The adhesive film according to one aspect of the present disclosure has a cured layer made of a cured product of the adhesive composition.

Conventionally, natural rubber-based adhesives or acrylic-based adhesives are known as adhesives for adhesive tapes or adhesive sheets. As acrylic adhesives, (co)polymers containing specific alkyl (meth)acrylates as essential structural units have been developed (for example, Patent Document 1: Japanese Patent Application Laid-Open No. 2004-143420).

However, according to the inventor's investigation, even with the technique of Patent Document 1, the adhesiveness was not sufficiently satisfactory.

Therefore, the inventor studied to provide a base material for an adhesive for producing an adhesive film with excellent adhesiveness and arrived at the present disclosure.

Hereinafter, an embodiment of the present disclosure will be described. In addition, the following embodiment is only one of various embodiments of the present disclosure. The following embodiments can be modified in various ways according to design as long as the purpose of the present disclosure can be achieved.

The base material (B) for an adhesive according to the present embodiment is 2-ethylhexyl acrylate (a1) and a branched alkyl (meta) group having a branched alkyl group having 4 to 10 carbon atoms other than 2-ethylhexyl acrylate (a1). At least one monomer selected from the group consisting of acrylate (a2), straight-chain alkyl (meth)acrylate (a3) having a straight-chain alkyl group having 1 to 4 carbon atoms, and nitrogen atom-containing monomer (a4) is included as a constituent monomer. It contains a copolymer (A). The carboxyl group concentration of the copolymer (A) is 0.08 mol/kg or less. The hydroxyl group concentration of the copolymer (A) is 0.05 mol/kg or less. The concentration of tertiary carbon derived from 2-ethylhexyl acrylate (a1) and branched alkyl (meth)acrylate (a2) in the copolymer (A) is 1.5 mol/kg or more and 5.0 mol/kg or less.

The adhesive film having a cured layer made of a cured product of the adhesive composition (X) containing the adhesive base material (B) of the present embodiment achieves the following effects.

(1) Excellent adhesion, that is, adhesion and holding power.

(2) The potter’s workmanship is excellent.

(3) Excellent adhesion on curved surfaces.

(4) Excellent corrosion resistance.

(5) Excellent heat resistance.

<Copolymer (A)>

Copolymer (A) in this embodiment includes 2-ethylhexyl acrylate (a1) (hereinafter also referred to as component (a1)) and branched alkyl groups having 4 to 10 carbon atoms other than component (a1). Alkyl (meth)acrylate (a2) (hereinafter also referred to as component (a2)), straight-chain alkyl (meth)acrylate (a3) having straight-chain alkyl having 1 to 4 carbon atoms (hereinafter also referred to as component (a3)) and at least one monomer selected from the group consisting of nitrogen atom-containing monomer (a4) (hereinafter also referred to as component (a4)) as a constituent monomer. Constituent monomers are monomers that constitute the copolymer (A) by polymerization. That is, the copolymer (A) is a polymer of constituent monomers including component (a1) and at least one monomer selected from the group consisting of component (a2), component (a3), and component (a4). In other words, the copolymer (A) contains at least one member selected from the group consisting of the residue of component (a1), the residue of component (a2), the residue of component (a3), and the residue of component (a4) as a structural unit. Included as.

<2-ethylhexyl acrylate (a1)>

The component (a1) in this embodiment is only 2-ethylhexyl acrylate.

<Branched alkyl (meth)acrylate (a2) having a branched alkyl group having 4 to 10 carbon atoms other than the component (a1)>

Component (a2) in this embodiment is, for example, 2-ethylhexyl methacrylate, neopentyl (meth)acrylate, isobutyl (meth)acrylate, isononyl (meth)acrylate, and isodecyl (meth)acrylate. ) Contains at least one type selected from the group consisting of acrylates.

And, (meth)acrylate means at least one of methacrylate and acrylate, and (meth)acrylic means at least one of methacrylic and acrylic.

Component (a2) preferably contains branched alkyl (meth)acrylate having a branched alkyl group having 4 to 8 carbon atoms, more preferably 2-ethylhexyl methacrylate and isobutyl (meth)acrylate. Contains at least one of them, particularly preferably contains isobutyl (meth)acrylate, and most preferably contains isobutyl acrylate.

<Linear chain alkyl (meth)acrylate (a3) having straight chain alkyl having 1 to 4 carbon atoms>

Component (a3) in this embodiment is, for example, from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propylmethyl (meth)acrylate, and n-butyl (meth)acrylate. Contains at least one selected type.

Component (a3) preferably contains at least one member selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate, and more preferably methyl acrylate. It contains at least one type selected from the group consisting of methyl acrylate, ethyl (meth)acrylate, and n-butyl acrylate, and particularly preferably contains methyl acrylate.

<Nitrogen atom-containing monomer (a4)>

The (a4) component in this embodiment is, for example, (meth)acrylamide (a41) (hereinafter also referred to as (a41) component), N-alkyl (meth)acrylamide having an alkyl group having 1 to 3 carbon atoms. (a42) (hereinafter also referred to as component (a42)), N,N-dialkyl (meth)acrylamide (a43) (hereinafter also referred to as component (a43)) having two alkyl groups each having 1 to 3 carbon atoms. ), N-vinyl monomer (a44) (hereinafter also referred to as component (a44)), which is a nitrogen-containing heterocyclic compound having a vinyl group, and N-(meth)acryloyl monomer (a45) (hereinafter also referred to as component (a45)) It contains at least one member selected from the group consisting of:

The component (a42) contains, for example, at least one member selected from the group consisting of N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, and N-propyl (meth)acrylamide.

Component (a43) is, for example, at least selected from the group consisting of N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, and N,N-dipropyl(meth)acrylamide. Contains 1 type.

(a44) Components include, for example, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-vinyl-2-pyrrolidone, N-vinylimidazole, 1-vinylimidazole, 4-vinylpyridine, 2- It contains at least one member selected from the group consisting of vinylpyridine, 2-vinylpyrazine, and N-vinyl-2-pyrrolidone.

(a45) Components include, for example, 4-(meth)acryloylmorpholine, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, and N-(meth)acryloylpiperidine. It contains at least one type selected from the group consisting of rolidine.

Component (a4) preferably contains at least one selected from the group consisting of (a43) component, (a44) component, and (a45) component, and more preferably N,N-dimethylacrylamide, 4- It contains at least one member selected from the group consisting of acryloylmorpholine and N-vinyl-2-pyrrolidone.

From the viewpoint of adhesion, the constituent monomer preferably contains component (a4), more preferably contains component (a3) and component (a4), or component (a2), component (a3), and (a4). Contains ingredients.

With respect to the total weight of the constituent monomers of the copolymer (A), the content of component (a1) is preferably 20% by weight or more and 65% by weight or less, more preferably 30% by weight or more and 55% by weight or less from the viewpoint of adhesiveness. am.

With respect to the total amount of monomers constituting the copolymer (A), the total content of component (a2), component (a3), and component (a4) is preferably 35% by weight or more and 80% by weight or less from the viewpoint of adhesiveness. Preferably it is 45% by weight or more and 70% by weight or less.

In addition, the weight ratio of component (a1) to the sum of component (a2), component (a3), and component (a4) [(a1) component/{(a2) component + (a3) component + (a4) component}] From the viewpoint of adhesion, it is preferably from 20/80 to 65/35, more preferably from 30/70 to 55/45.

When the constituent monomers of the copolymer (A) include component (a2), the content of component (a2) is preferably 0.1% by weight from the viewpoint of adhesiveness relative to the total weight of the constituent monomers of the copolymer (A). More preferably, it is 50% by weight or less, more preferably 1% by weight or more and 45% by weight or less.

When the constituent monomers of the copolymer (A) include component (a3), the content of component (a3) is preferably 0.1 weight from the viewpoint of adhesiveness relative to the total weight of the constituent monomers of the copolymer (A). % or more and 60% by weight or less, more preferably 1% by weight or more and 50% by weight or less.

When the constituent monomers of the copolymer (A) include component (a4), the content of component (a4) is preferably 3 weight from the viewpoint of adhesiveness relative to the total weight of the constituent monomers of the copolymer (A). % or more and 20% by weight or less, more preferably 5% by weight or more and 15% by weight or less.

The constituent monomers of the copolymer (A) may contain only the components (a1), (a2), (a3), and (a4), or may further contain monomers other than these. Constituent monomers include monomers other than component (a1), component (a2), component (a3), and component (a4), for example, monomer (a5) having a carboxyl group (hereinafter also referred to as component (a5)) It may contain at least one of the monomers (a6) (hereinafter also referred to as component (a6)) that do not have a carboxyl group. That is, the copolymer (A) may contain only the residues of component (a1), the residues of component (a2), the residues of component (a3), and the residues of component (a4) as structural units, and the residues of component (a1), In addition to the residue of component (a2), the residue of component (a3), and the residue of component (a4), at least one of the residue of component (a5) and the residue of component (a6) may be further included as a structural unit. .

The component (a5) is selected from the group consisting of monobasic acids such as (meth)acrylic acid and crotonic acid, polybasic acids such as maleic acid, itaconic acid and fumaric acid, anhydrides of the polybasic acids, and monoalkyl esters of the polybasic acids. Contains at least one type of

From the viewpoint of adhesiveness, component (a5) preferably contains at least one member selected from the group consisting of acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid, and more preferably contains acrylic acid.

The (a6) component is, for example, at least one selected from the group consisting of vinyl ester (a61) (hereinafter also referred to as (a61) component) and a monomer (a62) having a hydroxyl group (hereinafter also referred to as (a62) component). Contains species. The component (a61) contains, for example, at least one member selected from the group consisting of vinyl acetate, vinyl propionate, and vinyl butyrate. Component (a62) includes, for example, hydroxyalkyl (meth)acrylate (a621) (hereinafter also referred to as (a621) component) having a hydroxyalkyl group having 2 to 8 carbon atoms, and alkyl group having 2 to 8 carbon atoms. It contains at least one member selected from the group consisting of (meth)acrylic acid monoesterification of polyalkylene glycol having a lene group (a622) (hereinafter also referred to as (a622) component). (a621) The component is, for example, at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Contains species. (a622) The component contains, for example, polyethylene glycol mono(meth)acrylate.

From the viewpoint of adhesiveness, component (a6) preferably contains component (a62), more preferably contains 2-hydroxyethyl (meth)acrylate, and particularly preferably contains 2-hydroxyethyl acrylate. Contains

In addition, each of component (a1), component (a2), component (a3), component (a4), (a5), and (a6) may contain only one type of compound, or may contain two or more types of compounds. do.

From the viewpoint of adhesiveness, the content of component (a5) is preferably 5% by weight or less, more preferably 1% by weight or less, based on the total weight of the monomers constituting the copolymer (A).

Furthermore, with respect to the total weight of the constituents of copolymer (A), the content of component (a6) is preferably 20% by weight or less, more preferably 1% by weight or more and 15% by weight or less from the viewpoint of adhesiveness.

The carboxyl group concentration of the copolymer (A) in this embodiment is 0.08 mol/kg or less, preferably 0.05 mol/kg or less, and more preferably 0.03 mol/kg or less. If the carboxyl group concentration of the copolymer (A) exceeds 0.08 mol/kg, there is a problem of corrosion of the metal material. The carboxyl group concentration of the copolymer (A) may be 0 mol/kg, that is, the carboxyl group concentration of the copolymer (A) is 0 mol/kg or more. And, the carboxyl group concentration of the copolymer (A) is the number of moles of carboxyl groups that the copolymer (A) has per unit weight of the copolymer (A). The carboxyl group concentration can be calculated, for example, by measuring the acid value (KOH mg/g) of the copolymer (A) in accordance with JIS K0070 and using the result.

The carboxyl group concentration of the copolymer (A) can be adjusted, for example, by selecting the type of component (a5) in the constituent monomers of the copolymer (A) and adjusting the weight ratio.

The hydroxyl group concentration of the copolymer (A) in this embodiment is 0.05 mol/kg or less, and preferably 0.03 mol/kg or less. If the hydroxyl group concentration of the copolymer (A) exceeds 0.05 mol/kg, there is a problem of occurrence of thickening during high temperature coating. And, the hydroxyl group concentration of the copolymer (A) is the number of moles of hydroxyl groups that the copolymer (A) has per unit weight of the copolymer (A). This hydroxyl group concentration can be calculated by measuring the hydroxyl value (KOHmg/g) of the copolymer (A) in accordance with JIS K0070 and calculating it from the result.

The hydroxyl group concentration of the copolymer (A) can be adjusted, for example, by selecting the type of component (a62) in the constituent monomers of the copolymer (A) and adjusting the weight ratio.

The tertiary carbon concentration derived from the (a1) component and (a2) component of the copolymer (A) is 1.5 mol/kg or more and 5.0 mol/kg or less, preferably 1.9 mol/kg or more and 4.5 mol/kg or less, More preferably, it is 2.2 mol/kg or more and 4.0 mol/kg or less. If the tertiary carbon concentration derived from the (a1) component and (a2) component of the copolymer (A) is less than 1.5 mol/kg, the adhesive strength tends to be poor, and if it exceeds 5.0 mol/kg, the holding power tends to be poor. there is. The tertiary carbon concentration derived from the (a1) component and (a2) component of the copolymer (A) refers to the concentration of the (a1) component of the copolymer (A) per unit weight of the copolymer (A). It is the total number of moles of tertiary carbon derived from the 2-ethylhexyl group and tertiary carbon derived from the branched alkyl group of component (a2).

The tertiary carbon concentration is calculated as the number of moles of tertiary carbon per unit weight of the copolymer (A) based on the results of ¹ H-NMR measurement and ¹³ C-NMR measurement of the copolymer (A). In detail, the weight of copolymer (A) is determined by ¹ H-NMR measurement and ¹³ C-NMR measurement. The number of moles of tertiary carbon derived from the 2-ethylhexyl group of component (a1) and tertiary carbon derived from component (a2) are determined by ¹³ C-NMR measurement (DEPT method).

In addition, the tertiary carbon concentration can be adjusted appropriately, for example, by adjusting the weight ratio of component (a1) in the constituent monomers of copolymer (A), and selecting the type of component (a2) and adjusting the weight ratio. there is.

The weight average molecular weight (polystyrene equivalent) of the copolymer (A) determined by gel permeation chromatography (GPC) is preferably 100,000 or more and 500,000 or less, more preferably, from the viewpoint of improving adhesion and coating properties. It is 150,000 or more and 400,000 or less, especially preferably 200,000 or more and 300,000 or less.

The measurement conditions for gel permeation chromatography (GPC) in this embodiment are as follows.

-Device: “HLC-8120GPC” [manufactured by Tosoh Corporation]

-Columns: “Guardcolumn HXL-H” (1 piece) and “TSKgel GMHXL” (2 pieces) [all manufactured by Tosoh Corporation]

-Sample solution: 0.25% by weight tetrahydrofuran solution

-Solution injection volume: 100μl

-Flow rate: 1ml/min

-Measurement temperature: 40℃

-Detection device: refractive index detector

-Reference material: standard polystyrene

The glass transition temperature (Tg) of the copolymer (A) is preferably -15°C or higher and 10°C or lower, and more preferably -10°C or higher and 5°C or lower from the viewpoint of improving adhesion and improving coatability.

The glass transition temperature (Tg) is the loss coefficient (tanδ) obtained by measuring the copolymer (A) under the following conditions using a viscoelasticity measuring device (for example, model number MCR-302, manufactured by Anton Paar). The temperature was set to show the peak value.

-Jig: ø8mm parallel plate

-Sample thickness: 1㎜

-Irregularity: 1%

-Frequency: 1Hz

-Temperature increase rate: 5℃/min

-Temperature range: -50℃ to 180℃

In addition, the glass transition temperature (Tg) of the copolymer (A) can be adjusted appropriately by selecting the type of each monomer among the constituent monomers of the copolymer (A) and adjusting the weight ratio.

That is, for example, 2-ethylhexyl acrylate and n-butyl acrylate each tend to reduce Tg. Additionally, each of methyl (meth)acrylate and nitrogen atom-containing monomer (a4) tends to increase Tg. Additionally, methacrylate monomers tend to have a larger Tg than acrylate monomers.

The copolymer (A) in this embodiment can be synthesized by polymerizing the constituent monomers by a known polymerization method, such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization. In this case, known polymerization initiators, such as azo-based polymerization initiators such as azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), or azobisisovaleronitrile, or The constituent monomers can be polymerized in the presence of a peroxide-based polymerization initiator such as benzoyl peroxide, di-tert-butyl peroxide, or lauryl peroxide.

Among the above polymerization methods, solution polymerization is preferred in which constituent monomers are polymerized in the presence of a solvent (S). The solvent (S) includes, for example, hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; Halogenated hydrocarbons such as dichloromethane, trichloroethane, trichlorethylene, tetrachloroethylene, and dichloropropane; Alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, isobutyl alcohol, and diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane, and tetrahydrofuran; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, and ethyl butyrate; and polyols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate, and their derivatives. Contains at least one type. Through this solution polymerization, a mixture of the solvent (S) and the copolymer (A) is obtained. By separating the solvent (S) and copolymer (A) in this mixture, only copolymer (A) can be obtained. Additionally, the mixture of this solvent (S) and the copolymer (A) can be used as a base material (B) for an adhesive (B), which will be described later. In addition, the base material (B) for an adhesive can also be prepared by adjusting the content ratio of the solvent (S) in the mixture as necessary and adding appropriate additives to the mixture as needed.

<Material for adhesive (B)>

The base material (B) for an adhesive of this embodiment contains a copolymer (A). The base material for an adhesive (B) is preferable as a base material for the adhesive composition (X) described later.

The base material (B) for an adhesive consists, for example, of only the copolymer (A). Additionally, the adhesive base material (B) may contain a copolymer (A) and a solvent (S). Examples of the solvent (S) include the same solvent (S) used for polymerization of the copolymer (A). The proportion of the solvent (S) is preferably 30% by weight or less, more preferably 2% by weight or less, based on the weight of the base material (B) for the adhesive.

If necessary, the adhesive base material (B) may contain appropriate additives other than the copolymer (A) and the adhesive base material (B). In addition, it is preferable that the base material (B) for an adhesive does not contain a component having reaction hardening properties.

<Multifunctional (meth)acrylic monomer (C)>

The polyfunctional (meth)acrylic monomer (C) (hereinafter also referred to as (C) component) in this embodiment is a compound having a plurality of (meth)acryloyl groups in the molecule. (Meth)acryloyl group is one or both of acryloyl group and methacryloyl group. (C) Components include, for example, difunctional (meth)acrylic monomer (C1), trifunctional (meth)acrylic monomer (C2), tetrafunctional (meth)acrylic monomer (C3), and pentafunctional (meth)acrylic monomer (C3). It contains at least one type selected from the group consisting of monomer (C4) and the like.

Bifunctional (meth)acrylic monomer (C1) (hereinafter also referred to as (C1) component) has two (meth)acryloyl groups in the molecule.

Component (C1) includes, for example, a compound (C11) having the structure of an esterification product of 1 mole of a compound having 2 to 20 carbon atoms and 2 or more hydroxyl groups with 2 moles of (meth)acrylic acid;

A compound (C12) having the structure of an esterified product obtained by reaction of 1 mole of an alkylene oxide adduct of a compound having 2 to 20 carbon atoms and 2 or more hydroxyl groups with 2 moles of (meth)acrylic acid; and

A compound (C13) selected from the group consisting of compounds having the structure of an esterified product obtained by reaction of 1 mole of a lactone adduct of a compound having 2 to 20 carbon atoms and 2 or more hydroxyl groups with 2 moles of (meth)acrylic acid. Contains at least one type.

Regarding each of Compound (C11), Compound (C12), and Compound (C13), compounds having 2 to 20 carbon atoms and 2 or more hydroxyl groups include, for example, chain aliphatic alcohols with 2 to 20 carbon atoms and carbon atoms. It contains at least one type selected from the group consisting of alicyclic alcohols with 3 to 20 carbon atoms and aromatic hydroxyl group-containing compounds with 6 to 15 carbon atoms.

Chain aliphatic alcohols having 2 to 20 carbon atoms include, for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,4-butanediol, 1,6-hexanediol, Chain aliphatics with 2 to 20 carbon atoms, such as 1,8-octanediol, 1,10-decanediol, dodecanediol, tetradecanediol, neopentyl glycol, and 2,2-diethyl-1,3-propanediol. is alcohol; chain aliphatic trihydric alcohols having 3 to 20 carbon atoms, such as glycerin, trimethylolethane, and trimethylolpropane; and pentaerythritol, ditrimethylolpropane, sorbitol, mannitol, sorbitan, diglycerin, and dipentaerythritol, and at least one selected from the group consisting of chain aliphatic 4- to 8-carbon alcohols having 5 to 20 carbon atoms. .

Alicyclic alcohols having 3 to 20 carbon atoms include, for example, 1,3-cyclopentanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-cycloheptanediol, and 2,2-cycloheptanediol. -Dihydric alcohols such as bis(4-hydroxycyclohexyl)propane; and trihydric alcohols such as 1,3,5-cyclohexanetriol.

Aromatic hydroxyl group-containing compounds having 6 to 15 carbon atoms include, for example, pyrogallol, catechol, resorcinol, hydroquinone, dihydroxynaphthalene, bisphenol A, bisphenol F, bisphenol S, and 1,3,5- It contains at least one type selected from the group consisting of triazine-2,4,6-triol, etc.

Regarding compound (C12), the alkylene oxide preferably contains an alkylene oxide having 2 to 4 carbon atoms, and more specifically, for example, ethylene oxide (hereinafter, “ethylene oxide” is referred to as EO). (in some cases), 1,2-propylene oxide (hereinafter, “1,2-propylene oxide” may be referred to as PO), 1,3-propylene oxide, 1,2-butylene oxide, 1,3- It contains at least one type selected from the group consisting of butylene oxide, 1,4-butylene oxide, and 2,3-butylene oxide.

From the viewpoint of adhesiveness, the alkylene oxide preferably contains at least one of EO and PO, and more preferably contains PO.

Regarding compound (C12), the number of added moles of alkylene oxide per mole in the alkylene oxide adduct of the compound having 2 to 20 carbon atoms and 2 or more hydroxyl groups is preferably 1 mole or more and 40 moles or less.

Regarding compound (C13), lactones include, for example, lactones having 2 to 12 carbon atoms, and more specifically, for example, acetolactone, propiolactone, butyrolactone, valerolactone, caprolactone, and It contains at least one type selected from the group consisting of laurolactone and the like.

Regarding compound (C13), the number of added moles of lactone per mole in the lactone adduct of the compound having 2 to 20 carbon atoms and 2 or more hydroxyl groups is preferably 1 mole or more and 15 moles or less.

(C1) Components include, for example, 1,6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and 2,4-dimethyl. -1,5-pentanediol di(meth)acrylate, butyl ethyl propanediol di(meth)acrylate, di(meth)acrylate of a compound obtained by adding alkylene oxide having 2 to 4 carbon atoms to cyclohexane methanol, Polypropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, 2-ethyl-2-butyl-butanediol di(meth)acrylate, bisphenol A with carbon number 2 Di(meth)acrylate of a compound obtained by adding an alkylene oxide having ∼4 carbon atoms, di(meth)acrylate of a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to bisphenol F, 1,4-butanediol di(meth) ) It contains at least one type selected from the group consisting of acrylate, 2-ethyl-2-butyl-propanediol di(meth)acrylate, and 1,9-nonanediol di(meth)acrylate.

The trifunctional (meth)acrylic monomer (C2) (hereinafter also referred to as (C2) component) has three (meth)acryloyl groups in the molecule. The component (C2) includes, for example, a compound (C21) having the structure of an esterification product of 1 mole of a compound having 2 to 20 carbon atoms and 3 or more hydroxyl groups with 3 moles of (meth)acrylic acid; A compound (C22) having the structure of an esterification of 1 mole of an alkylene oxide adduct of a compound having 2 to 20 carbon atoms and 3 or more hydroxyl groups with 3 moles of (meth)acrylic acid; and at least one selected from the group consisting of a compound (C23) having the structure of an esterification of 1 mole of a lactone adduct of a compound having 2 to 20 carbon atoms and 3 or more hydroxyl groups with 3 moles of (meth)acrylic acid. Contains species.

For each of Compound (C21), Compound (C22), and Compound (C23), compounds having 2 to 20 carbon atoms and 3 or more hydroxyl groups are, for example, 2 to 20 carbon atoms for component (C1) above. And, of the compounds exemplified as compounds having two or more hydroxyl groups, it contains at least one selected from the group consisting of compounds having three or more hydroxyl groups.

Regarding compound (C22), the compound that may contain alkylene oxide may be the same as that of compound (C12), and the added mole number of alkylene oxide may also be the same as that of compound (C12). Additionally, with respect to Compound (C23), the compound in which lactone may be contained may be the same as in the case of Compound (C13) above, and the added mole number of lactone may also be the same as in the case of Compound (C13) above.

The (C2) component is, for example, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tri(meth)acrylate, a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to trimethylolpropane. ) Acrylate, glycerin tri(meth)acrylate, tri(meth)acrylate of a compound obtained by adding alkylene oxide with 2 to 4 carbon atoms to glycerin, pentaerythritol tri(meth)acrylate, pentaerythritol with 2 carbon atoms Tri(meth)acrylate, dipentaerythritol tri(meth)acrylate of a compound obtained by adding an alkylene oxide having ∼4, and tri(meth) of a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to dipentaerythritol. It contains at least one type selected from the group consisting of acrylates, sorbitol tri(meth)acrylate, and tri(meth)acrylates of compounds obtained by adding an alkylene oxide having 2 to 4 carbon atoms to sorbitol.

The tetrafunctional (meth)acrylic monomer (C3) (hereinafter also referred to as (C3) component) has four (meth)acryloyl groups in the molecule. Component (C3) includes, for example, a compound (C31) having the structure of an esterification product of 1 mole of a compound having 2 to 20 carbon atoms and 4 or more hydroxyl groups with 4 moles of (meth)acrylic acid; A compound (C32) having the structure of an esterification of 1 mole of an alkylene oxide adduct of a compound having 2 to 20 carbon atoms and 4 or more hydroxyl groups with 4 moles of (meth)acrylic acid; and at least one selected from the group consisting of a compound (C33) having the structure of an esterification of 1 mole of a lactone adduct of a compound having 2 to 20 carbon atoms and 4 or more hydroxyl groups with 4 moles of (meth)acrylic acid. Contains species.

Regarding each of Compound (C31), Compound (C32) and Compound (C33), the compound having 2 to 20 carbon atoms and 4 or more hydroxyl groups is, for example, a compound having 2 to 2 carbon atoms in relation to component (C1) above. 20, and among the compounds exemplified as compounds having 2 or more hydroxyl groups, it contains at least one selected from the group consisting of compounds having 4 or more hydroxyl groups.

Regarding compound (C32), the compound that may contain alkylene oxide may be the same as that of compound (C12), and the added mole number of alkylene oxide may also be the same as that of compound (C12). Additionally, with respect to Compound (C33), the compound in which lactone may be contained may be the same as in the case of Compound (C13) above, and the added mole number of lactone may also be the same as in the case of Compound (C13) above.

(C3) Components include, for example, pentaerythritol tetra(meth)acrylate, tetra(meth)acrylate of a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to pentaerythritol, sorbitol tetra(meth)acrylate, Tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, a compound in which an alkylene oxide having 2 to 4 carbon atoms is added to sorbitol, and an alkylene oxide having 2 to 4 carbon atoms is added to ditrimethylolpropane. From the group consisting of tetra(meth)acrylate of a compound, dipentaerythritol tetra(meth)acrylate, and tetra(meth)acrylate of a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to dipentaerythritol. Contains at least one selected type.

The pentafunctional or higher (meth)acrylic monomer (C4) (hereinafter also referred to as the (C4) component) has five or more (meth)acryloyl groups in the molecule. Component (C4) includes, for example, a compound (C41) having the structure of an esterification of 1 mole of a compound having 2 to 20 carbon atoms and 5 or more hydroxyl groups with 5 mole or more (meth)acrylic acid; A compound (C42) having the structure of an esterification of 1 mole of an alkylene oxide adduct of a compound having 2 to 20 carbon atoms and 5 or more hydroxyl groups with 5 mole or more (meth)acrylic acid; and at least a compound (C43) selected from the group consisting of a compound (C43) having the structure of an esterification of 1 mole of a lactone adduct of a compound having 2 to 20 carbon atoms and 5 or more hydroxyl groups with 5 mol or more (meth)acrylic acid. Contains 1 type.

For each of Compound (C41), Compound (C42), and Compound (C43), compounds having 2 to 20 carbon atoms and 5 or more hydroxyl groups are, for example, 2 to 20 carbon atoms for component (C1) above. And, of the compounds exemplified as compounds having two or more hydroxyl groups, it contains at least one selected from the group consisting of compounds having five or more hydroxyl groups.

Regarding compound (C42), the compound that may contain alkylene oxide may be the same as that of compound (C12), and the added mole number of alkylene oxide may also be the same as that of compound (C12). Additionally, with respect to Compound (C43), the compound in which lactone may be contained may be the same as in the case of Compound (C13) above, and the added mole number of lactone may also be the same as in the case of Compound (C13) above.

(C4) Components include, for example, sorbitol penta(meth)acrylate, penta(meth)acrylate of a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to sorbitol, dipentaerythritol penta(meth)acrylate, Penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, a compound in which an alkylene oxide having 2 to 4 carbon atoms is added to dipentaerythritol, and an alkylene oxide having 2 to 4 carbon atoms is added to dipentaerythritol. hexa(meth)acrylate of the compound, sorbitol hexa(meth)acrylate, hexa(meth)acrylate of the compound obtained by adding alkylene oxide with 2 to 4 carbon atoms to sorbitol, and caprolactone-modified dipentaerythritol hexa(meth) ) Contains at least one type selected from the group consisting of acrylates, etc.

In this embodiment, from the viewpoint of improving adhesion, component (C) preferably contains a compound having 2 to 6 (meth)acryloyl groups in the molecule, and more preferably contains a (meth)acryloyl group in the molecule. Contains compounds having 2 to 5 groups.

(C) Component may contain only one type of compound, or may contain two or more types of compounds.

From the viewpoint of improving adhesion, the molecular weight of component (C) is preferably 150 or more and 600 or less, and more preferably 200 or more and 550 or less. In addition, the molecular weight of component (C) is the formula weight when component (C) contains only one type of compound, and when component (C) contains two or more types of compounds, it is measured by gel permeation chromatography (GPC). It is the number average molecular weight obtained by .

The measurement conditions for gel permeation chromatography (GPC) of component (C) in this embodiment are as follows.

-Device: “Waters Alliance 2695” [manufactured by Waters]

-Column: “Guardcolumn Super H-L” (1 piece) and “TSKgel SuperH2000 (1 piece)” [all manufactured by Tosoh Corporation]

-Sample solution: 0.25% by weight tetrahydrofuran solution

-Solution injection volume: 10μl

-Flow rate: 0.6ml/min

-Measurement temperature: 40℃

-Detection device: refractive index detector

-Reference material: standard polyethylene glycol

The molecular weight (molecular weight/number of (meth)acryloyl groups) per (meth)acryloyl group of component (C) is preferably 100 or more and 300 or less, more preferably 120 or more and 200 from the viewpoint of improving adhesion. It is as follows.

<Adhesive composition>

The adhesive composition (X) of the present embodiment contains the adhesive main agent (B) and component (C).

The weight ratio of the base material (B) for an adhesive (B) to the component (C) in the adhesive composition (X) [main base material (B)/component (C) for an adhesive] is preferably 100/10 to 100 from the viewpoint of improving adhesion. /0.5, more preferably from 100/5 to 100/1.

The adhesive composition (X) of the present embodiment can be produced, for example, by mixing the adhesive base material (B) containing the copolymer (A) and the component (C).

The adhesive composition (X) may contain a solvent (S). That is, the adhesive composition (X) may be a solution of the solvent (S). For example, when the base material (B) for an adhesive contains a solvent (S), the adhesive composition (X) also contains a solvent (S). From the viewpoint of improving handleability, the proportion of solvent (S) in the adhesive composition (X) is preferably 50% by weight or less, more preferably 5% by weight or less, especially with respect to the weight of the adhesive composition (X). Preferably it is 1% by weight or less.

In addition, the adhesive composition (X) of the present embodiment may further contain additives as needed within a range that does not impair the effect of the present disclosure. The additive contains at least one selected from the group consisting of, for example, a tackifier (N) such as terpene resin and rosin resin, a photopolymerization initiator (D), a plasticizer, a filler, a pigment, an ultraviolet absorber, and an antioxidant. .

The adhesive composition of this embodiment may further contain an antioxidant (E).

When the adhesive composition contains an antioxidant (E), the generation of minute crosslinked products in the cured product of the adhesive composition (X) can be further suppressed, and coloring of the cured product and the adhesive sheet at high temperatures can be suppressed.

The antioxidant (E) in this embodiment is, for example, at least one selected from the group consisting of hindered phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, lactone-based antioxidants, and amine-based antioxidants. Contains

Hindered phenol-based antioxidants include, for example, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), and triethylene glycol-bis. [3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], pentaerystyryl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxy phenyl)propionate] and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

The sulfur-based antioxidant contains, for example, at least one selected from the group consisting of dilauryl 3,3'-thiodipropionate and distearyl 3,3'-thiodipropionate.

Phosphorus-based antioxidants contain, for example, organic phosphites that may have halogen. Phosphorus-based antioxidants include, for example, triphenyl phosphite, triisodecyl phosphite, tris (2,4-di-tert-butylphenyl) phosphite, and 2,2-methylenebis (4,6-di-tert- It contains at least one type selected from the group consisting of butylphenyl)octylphosphite and halo-substituted products thereof.

Lactone-based antioxidants include, for example, reaction products of 5,7-di-tert-butyl-3-hydroxybenzo[b]furan-2(3H)-one and o-xylene.

Amine-based antioxidants contain hindered aromatic amines, for example. The amine antioxidant contains, for example, at least one selected from the group consisting of octyldiphenylamine, N-n-butyl-p-aminophenol, and N,N-diisopropyl-p-phenylenediamine.

The antioxidant (E) preferably contains at least one selected from the group consisting of hindered phenol-based antioxidants, phosphorus-based antioxidants, and lactone-based antioxidants, from the viewpoint of suppressing cross-linked product generation and coloring. , more preferably contains at least one of a hindered phenol-based antioxidant with a molecular weight of 700 to 2000 and a phosphorus-based antioxidant with a molecular weight of 700 to 2000, and particularly preferably contains a phosphorus-based antioxidant with a molecular weight of 700 to 2000. . Antioxidants may contain only one type of compound or may contain two or more types of compounds.

When the adhesive composition (X) of the present embodiment contains an antioxidant (E), the weight ratio of the copolymer (A) and the antioxidant (E) [copolymer (A):antioxidant (E)] is crosslinked. From the viewpoint of suppressing water generation, the ratio is preferably from 100:0.001 to 100:3, more preferably from 100:0.005 to 100:1, and particularly preferably from 100:0.01 to 100:0.5.

<Adhesive film>

The adhesive film of this embodiment has a cured layer made of a cured product of adhesive composition (X). The thickness of the cured layer is preferably 10 μm or more and 200 μm or less, and more preferably 20 μm or more and 100 μm or less. The adhesive film, for example, consists of only a cured layer. Additionally, the adhesive film may include a film-shaped base material and a cured layer overlapping the base material.

The adhesive film of the present embodiment is made by applying the adhesive composition ( It can be manufactured by curing with (UV, electron beam, etc.).

As a preferred form of use, as in the Examples described later, the pressure-sensitive adhesive composition (X) is softened or melted by heating, then applied to a substrate and further cured with active energy rays. That is, the adhesive composition (X) can also be referred to as an active energy ray-curable hot melt adhesive composition.

The substrate is, for example, film-shaped or sheet-shaped. The substrate is, for example, plastic film, plastic sheet, plastic foam, flat yarn, paper, metal plate, metal foil, woven fabric, non-woven fabric or wood. Plastics include, for example, at least one member selected from the group consisting of polyolefins such as polyethylene and polypropylene, polyurethane, polyethylene terephthalate, polyvinyl chloride, rayon, and polyamide. The paper is, for example, Japanese paper or crepe paper.

The adhesive composition (X) containing the adhesive base material (B) of the present embodiment is excellent in coatability, and the adhesive film having a cured layer made of a cured product of the adhesive composition (X) is excellent in adhesiveness, so the adhesive film Silver is used for packaging (packaging of frozen foods, binding of vegetables, etc.), for marking (car molds, emblems, marks, etc.), for masking (glass sealing, building curing, etc.), for surface protection (protection of painted surfaces, etc.), for medical use ( It can be preferably used for various purposes such as bandages, etc.) and office use. Moreover, since the adhesive film of this embodiment has excellent adhesiveness on curved surfaces, it can also be suitably used for protecting curved substrates (curved displays, curved electronic substrates).

<Example>

Hereinafter, the present embodiment will be further described through examples and comparative examples, but the present embodiment is not limited to these.

<Example 1>

100 parts by weight of ethyl acetate as a solvent was charged into a reaction vessel equipped with a stirrer, thermometer, reflux cooling pipe, dropping funnel, and nitrogen gas introduction pipe, and the temperature was raised to 78°C.

Next, while blowing nitrogen into the reaction vessel under solvent reflux, the monomer mixture liquid having the following composition and the initiator solution 1 having the following composition were continuously dropped into the reaction vessel over 5 hours using a dropping funnel, and reaction was carried out. Radical polymerization proceeded within the vessel.

Composition of monomer mixture: 44 parts by weight of 2-ethylhexyl acrylate (a1-1), 46 parts by weight of methyl acrylate (a3-2), and 10 parts by weight of N-vinyl-2-pyrrolidone (a4-1). wealth

Composition of reaction initiator solution 1: 0.20 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) [hereinafter sometimes abbreviated as V-65] and 20 parts by weight of ethyl acetate.

After the dropwise addition was completed, the initiator solution 2 having the following composition was continuously dripped into the reaction vessel over 1 hour using a dropping funnel while stirring the liquid in the reaction vessel while maintaining the inside of the reaction vessel at 78°C. Additionally, after the polymerization reaction in the reaction vessel was continued for 1 hour under solvent reflux, the liquid in the reaction vessel was heated to 130°C under reduced pressure to distill off ethyl acetate. In this way, the adhesive base material (B-1) containing copolymer (-1) was prepared in the reaction vessel. This adhesive base material (B-1) was taken out from the reaction container.

Composition of initiator solution 2: 0.11 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) and 10 parts by weight of ethyl acetate.

And, the weight average molecular weight (Mw) of copolymer (A-1) is 260,000, glass transition temperature (Tg) is 2℃, carboxyl group concentration is 0 mol/kg, hydroxyl group concentration is 0 mol/kg, and tertiary carbon concentration. was 2.39 mol/kg.

<Examples 2 to 14, Comparative Examples 1 to 8>

The compositions of the monomer blend solution, initiator solution 1, and initiator solution 2 were changed as shown in Tables 1 to 3, and other things were the same as in Example 1, and copolymers (A-2) to (A-22) were produced. Bases for adhesives (B-2) to (B-22) each containing were obtained. Tables 1 to 3 show the weight average molecular weight, glass transition temperature, carboxyl group concentration, hydroxyl group concentration, and tertiary carbon concentration of copolymers (A-2) to (A-22).

[Table 1]

[Table 2]

[Table 3]

<Examples 21 to 40, Comparative Examples 21 to 28>

The ingredients shown in the “Blending Composition” in Tables 4 to 6 were blended for 3 minutes in a Henschel mixer, and then melt-kneaded in a vented twin-screw extruder under the conditions of 150°C, 100 rpm, and a residence time of 3 minutes. Thus, adhesive compositions (X-1) to (X-28) were obtained.

The following adhesive films (Yα) and adhesive films (Yβ) were produced from each of the adhesive compositions (X-1) to (X-28), and evaluated by the method described later. The results are shown in Tables 4 to 6.

<Production of adhesive film (Yα)>

Each of the adhesive compositions (X-1) to (X-28) was melted at 150°C, and under an environmental temperature of 23°C, a 25-μm-thick polyester film (manufactured by Toray Co., Ltd., product name Lumira Type T, polyethylene) was melted at 150°C. Terephthalate (PET) film] was coated on the surface using a slot coater at an application rate of 30 g/m2 to produce a coating film. This coating film is cured by using a UV irradiation device (model number UVC-02516S1AA01, manufactured by Ushio Denki Co., Ltd.), using a metal halide lamp as a light source, and irradiating ultraviolet rays under conditions of an accumulated light amount of 1000 mJ/cm2, A cured layer with a thickness of 30 μm was produced. As a result, an adhesive film (Yα) including a polyester film and a cured layer overlapping therewith was obtained.

<Production of adhesive film (Yβ)>

Each of the adhesive compositions (X-1) to (X-28) was melted at 150°C, and under an environmental temperature of 23°C, a 150-μm-thick polyester film (manufactured by Toray Co., Ltd., product name Lumira Type T, polyethylene) was melted at 150°C. A coating film was produced by coating on the surface of [Terephthalate (PET) film] at a coating amount of 30 g/m2 using a slot coater. This coating film is cured by using a UV irradiation device [Ushio Denki Co., Ltd., model number UVC-02516S1AA01], using a metal halide lamp as a light source, and irradiating ultraviolet rays under the condition of an accumulated light amount of 1000 mJ/cm2, A cured layer with a thickness of 30 μm was produced. As a result, an adhesive film (Yβ) comprising a polyester film and a cured layer overlapping therewith was obtained.

<1> Dogongseong

The appearance of the surface of the cured layer of the adhesive film (Yα) was observed with the naked eye and evaluated according to the following evaluation criteria.

<Evaluation criteria>

AA: There is no coating unevenness at all.

A: There is some coating unevenness.

B: There is partial coating unevenness.

C: There is coating unevenness overall.

<2> Adhesion (adhesiveness)

An adhesive film test piece with dimensions of 100 mm x 25 mm in plan view was cut from the adhesive film (Yα). Additionally, a polyethylene terephthalate film with a thickness of 0.18 mm with an ITO (indium tin oxide) film overlapping on one side was prepared. In an atmosphere of 25°C, an adhesive film test piece and a polyethylene terephthalate film were overlapped so that the cured layer and the ITO film were in contact, based on the “Adhesive Tape and Adhesive Sheet Test Method” specified in JIS Z0237-2009. Subsequently, a load of 2 kg was applied with a roller on the polyethylene terephthalate film, and the roller was moved one round and round on the polyethylene terephthalate film. As a result, the adhesive film test piece and the polyethylene terephthalate film were bonded together to obtain a laminated film.

This laminated film was left to stand for 1 day under conditions of a temperature of 25°C and a relative humidity of 50%, and then the 180° peel strength of an adhesive film test piece to a polyethylene terephthalate film was measured in a 25 mm width, tensile ( It was measured under conditions of a speed of 300 mm/min. The results were evaluated based on the following evaluation criteria.

<Evaluation criteria>

AA: greater than 15N/25mm

A: Greater than 10N/25mm, less than 15N/25mm

B: Greater than 5N/25mm, less than 10N/25mm

C: 5N/25㎜ or less

<3> Holding power (adhesiveness)

An adhesive film test piece with dimensions of 100 mm x 12 mm in plan view was cut from the adhesive film (Yα). Additionally, a stainless steel plate with dimensions of 100 mm x 100 mm in plan view was prepared. The adhesive film (Yα) and the stainless steel plate were overlapped so that the hardened layer and the stainless steel plate were in contact and the contact area was 12 mm x 12 mm in plan view. Subsequently, a load of 2 kg was applied with a roller on the polyethylene terephthalate film, and the roller was moved one round and round on the polyethylene terephthalate film. In this way, the adhesive film (Yα) and the stainless steel plate were bonded to obtain a laminate. This laminate was left to stand in an atmosphere of 40°C for 30 minutes.

Next, in an atmosphere of 40°C, the stainless steel plate is placed vertically so that the portion in contact with the adhesive film (Yα) is disposed at the bottom, and in this state, the adhesive film (Yα) on the stainless steel plate does not overlap. At the lower end of the portion measuring 88 mm x 12 mm, a downward load of 1 kg was applied to the upper end of the adhesive film Yα for 24 hours. Subsequently, the downward displacement of the adhesive film (Yα) with respect to the stainless steel plate (unit: mm) was measured and evaluated based on the following evaluation criteria. And, the smaller the number, the higher the holding power.

<Evaluation criteria>

AA: 0.5 mm or less

A: More than 0.5 mm, less than 1.0 mm

B: More than 1.0 mm, less than 2.0 mm

C: Exceeding 2.0mm

<4> Adhesion on curved surfaces (curved surface peel test)

From the adhesive film (Yβ), an adhesive film test piece with dimensions of 40 mm x 40 mm in plan view was cut out. Five adhesive film test pieces were prepared and attached to each of five glass tubes with an outer diameter of 30 mm.

Next, each glass tube was left to stand in an atmosphere at 23°C for 24 hours, and then the length of the portion of the adhesive film test piece peeled off from the glass tube was measured. For each glass tube, the sum of the length of the peeled portion at one end of the adhesive film test piece and the length of the peeled portion at the other end was calculated. The average value of the sum of the above-mentioned lengths for the five glass tubes was calculated, and the results were evaluated according to the following evaluation criteria. And, the smaller the value, the better the adhesiveness on curved surfaces.

<Evaluation criteria>

AA: 0.5 mm or less

A: More than 0.5 mm, less than 1.0 mm

B: More than 1.0 mm, less than 2.0 mm

C: Exceeding 2.0mm

<5> Corrosion test

An adhesive film test piece with dimensions of 100 mm x 25 mm in plan view was cut from the adhesive film (Yα). Additionally, a polyethylene terephthalate film with a thickness of 0.18 mm with an ITO (indium tin oxide) film overlapping on one side was prepared. Under an atmosphere of 25°C, based on JIS Z0237-2009 “Testing method for adhesive tape and adhesive sheet,” an adhesive film test piece and a polyethylene terephthalate film were overlapped so that the cured layer and the ITO film were in contact. Subsequently, a load of 2 kg was applied to the roller on the polyethylene terephthalate film, and the roller was moved one round and round on the polyethylene terephthalate film. In this way, the adhesive film test piece and the polyethylene terephthalate film were bonded to obtain a laminated film.

This laminated film was left for 14 days under conditions of a temperature of 25°C and a relative humidity of 90%, and then a peeling test was performed at 180° of an adhesive film test piece to a polyethylene terephthalate film in an atmosphere of 25°C.

Subsequently, the electrical resistance value (R ₁ ) of the ITO film in the polyethylene terephthalate film was measured. In addition, the electrical resistance value (R ₀ ) of the ITO film in the polyethylene terephthalate film before being attached to the adhesive film test piece was measured in advance. Based on these, the change rate of the electrical resistance value of the ITO film was calculated using the equation below, and the results were evaluated using the following evaluation criteria. And, the smaller the change rate of the resistance value, the less corrosiveness it means, and the better it is.

Rate of change (%)=(R ₁ -R ₀ )/R ₀ ×100

<Evaluation criteria>

AA: change rate less than 5%

A: Change rate more than 5%, less than 10%

B: Change rate more than 10%, less than 20%

C: Change rate of 20% or more

<6> Heat resistance test

Each of the copolymers (i.e., copolymers (A-1) to (A-22)) used to prepare adhesive compositions (X-1) to (X-28) were depressurized to 150°C and a gauge pressure of -100 kPa. After conducting a heat resistance test in which the product was allowed to stand for 7 hours under the following conditions, the weight average molecular weight was measured by gel permeation chromatography. The rate of change of the weight average molecular weight after this heat resistance test from the weight average molecular weight before the heat resistance test (weight average molecular weight shown in Tables 1 to 3) was calculated using the formula below, and evaluated based on the following criteria.

Rate of change (%) = (weight average molecular weight after heat resistance test)/(weight average molecular weight before heat resistance test) × (100)

<Evaluation criteria>

AA: Rate of change greater than 100% but less than 105%

A: Rate of change greater than 105% but less than 110%

B: Rate of change greater than 110% but less than 120%

C: Rate of change greater than 120%

[Table 4]

[Table 5]

[Table 6]

The details of the polyfunctional (meth)acrylate and initiator in Tables 4 to 6 are as follows.

- Multifunctional (meth)acrylate (C-1): Product name: Neoma TA-505, manufactured by Sanyo Kasei Kogyo Co., Ltd., triacrylate of PO (propylene oxide) adduct of trimethylolpropane, number average molecular weight 460

-Multifunctional (meth)acrylate (C-2): Product name: Neoma DA-600, manufactured by Sanyo Kasei Kogyo Co., Ltd., dipentaerythritol pentaacrylate, number average molecular weight: 540

-Multifunctional (meth)acrylate (C-3): Product name: Neoma TA-401, manufactured by Sanyo Kasei Kogyo Co., Ltd., triacrylate of EO adduct of trimethylolpropane, number average molecular weight 405

-Multifunctional (meth)acrylate (C-4): 1,6-hexanediol diacrylate, manufactured by Osaka Yuki Kagaku Kogyo Co., Ltd., number average molecular weight 226

-Initiator (D-1): Product name SB-PI 712, manufactured by Sanyo Boeki Co., Ltd., 4-methylbenzophenone

From the results in Tables 1 to 6, the adhesive films of Examples 21 to 40 are superior to the adhesive films of Comparative Examples 21 to 28, and are superior in adhesion (adhesion and holding power) and coatability, and have better adhesion on curved surfaces. You can see that it is better.

Claims (6)

2-ethylhexyl acrylate (a1); and
Branched alkyl (meth)acrylate (a2) having a branched alkyl group having 4 to 10 carbon atoms other than the 2-ethylhexyl acrylate (a1), and straight chain alkyl (meth)acrylate having a straight chain alkyl group having 1 to 4 carbon atoms. At least one monomer selected from the group consisting of (a3) and nitrogen atom-containing monomer (a4);
Contains a copolymer (A) containing as a constituent monomer,
The carboxyl group concentration of the copolymer (A) is 0.08 mol/kg or less,
The hydroxyl group concentration of the copolymer (A) is 0.05 mol/kg or less,
The tertiary carbon concentration derived from the 2-ethylhexyl acrylate (a1) and the branched alkyl (meth)acrylate (a2) of the copolymer (A) is 1.5 mol/kg or more and 5.0 mol/kg or less,
Topics for adhesives. According to paragraph 1,
A base material for an adhesive wherein the weight average molecular weight of the copolymer (A) is 100,000 or more and 500,000 or less. According to paragraph 1,
A base material for an adhesive wherein the glass transition temperature of the copolymer (A) is -15°C or higher and 10°C or lower. The base material for an adhesive according to any one of claims 1 to 3; and
An adhesive composition containing polyfunctional (meth)acrylate (C). According to clause 4,
An adhesive composition wherein the weight ratio of the adhesive base material (B) to the polyfunctional (meth)acrylate (C) is from 100/10 to 100/0.5. An adhesive film having a cured layer made of a cured product of the adhesive composition according to claim 4.