Adhesive composition, adhesive, and adhesive sheet

Abstract

The present invention provides an adhesive composition that can be applied to applications requiring transparency and exhibits excellent adhesive properties upon curing, an adhesive obtained by crosslinking the adhesive composition, and an adhesive sheet having an adhesive layer made of the adhesive. [Solution] An adhesive composition containing an acrylic resin (A) and an acrylic resin (B), wherein the acrylic resin (A) has structural units derived from a hydroxyl group-containing monomer (a1) and has a glass transition temperature of -30°C or lower, and the acrylic resin (B) has structural units derived from a branched alkyl methacrylate (b1-1) having 4 carbon atoms in more than 50% by mass of the total structural units, has a weight-average molecular weight of 10,000 or more and 100,000 or less, and has a glass transition temperature of 48°C or higher.

Claims

1. An adhesive composition containing acrylic resin (A) and acrylic resin (B), The acrylic resin (A) has structural units derived from a hydroxyl group-containing monomer (a1), and has a glass transition temperature of -30°C or lower. The acrylic resin (B) is an adhesive composition having more than 50% by mass of structural units derived from a branched alkyl methacrylate (b1-1) having 4 carbon atoms in the total structural units, a weight-average molecular weight of 10,000 or more and 100,000 or less, and a glass transition temperature of 48°C or higher.

2. The adhesive composition according to claim 1, wherein the acrylic resin (A) has structural units derived from alkyl (meth)acrylate (a2) having 1 to 30 carbon atoms.

3. The adhesive composition according to claim 2, wherein the content of structural units derived from the C1-C30 alkyl (meth)acrylate (a2) is 50 to 98% by mass with respect to the total structural units of the acrylic resin (A).

4. The adhesive composition according to claim 2, wherein the content of structural units derived from the hydroxyl group-containing monomer (a1) is 0.5 to 10% by mass with respect to the total structural units of the acrylic resin (A).

5. The adhesive composition according to claim 1, wherein the weight-average molecular weight of the acrylic resin (A) is 600,000 to 1,500,000.

6. The adhesive composition according to claim 1, wherein the branched alkyl methacrylate (b1-1) having 4 carbon atoms is t-butyl acrylate.

7. The adhesive composition according to claim 1, wherein the content of the acrylic resin (B) is 0.1 to 5 parts by mass per 100 parts by mass of the acrylic resin (A).

8. The adhesive composition according to claim 1, further containing a crosslinking agent (C).

9. The adhesive composition according to claim 8, wherein the crosslinking agent (C) contains an active energy ray crosslinking agent (c1).

10. The adhesive composition according to claim 9, wherein the active energy ray crosslinking agent (c1) contains a polyfunctional (meth)acrylate.

11. The adhesive composition according to claim 1, further containing a photopolymerization initiator (D).

12. An adhesive comprising a crosslinked adhesive composition according to any one of claims 1 to 11.

13. The adhesive according to claim 12, wherein crosslinking is performed by irradiation with active energy rays.

14. An adhesive sheet having an adhesive layer made of the adhesive described in claim 12.

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