Modified acrylic block copolymer, method for producing same, and intended use of same

1. A modified acrylic block copolymer, comprising:

a polymer block (A) comprising a (meth)acrylic acid ester unit (a), and

a polymer block (B) comprising an N-substituted (meth)acrylamide unit (d) and a (meth)acrylic acid ester unit (b) and/or a (meth)acrylic acid unit (c), wherein the (meth)acrylic acid ester unit (b) is structurally different from the (meth)acrylic acid ester unit (a);

wherein

a ratio (Mw/Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) is 1.0 to 1.5, and

the polymer block (B) satisfies the following relationships:

5<([ d]+[c ])<90; and

0.01<[ d]/[c]< 0.075×([ d]+[c ])+4;

wherein

[d] is a molar amount of the N-substituted (meth)acrylamide unit (d) relative to 100 mol of total molar amount of units constituting the polymer block (B) and

[c] is a molar amount of the (meth)acrylic acid unit (c) relative to 100 mol of total molar amount of units constituting the polymer block (B).

2. The modified acrylic block copolymer according to claim 1 , wherein the (meth)acrylic acid ester unit (a) is an alkyl (meth)acrylate unit that is not a methyl (meth)acrylate unit.

3. The modified acrylic block copolymer according to claim 1 , wherein the (meth)acrylic acid ester unit (b) is a methyl (meth)acrylate unit.

4. The modified acrylic block copolymer according to claim 1 , wherein the N-substituted (meth)acrylamide unit (d) is a unit represented by Formula (Ia) or (Ib):

in Formulae (Ia) and (Ib), each of R 1 , R 2 , and R 3 independently represents an alkyl group optionally having a substituent, a silyl group, an amino group optionally having a substituent, a silanyl group, an alicyclic group optionally having a substituent, a heterocyclic group optionally having a substituent, or an aromatic ring group optionally having a substituent, R 1 and R 2 together with the nitrogen atom to which they are bound optionally form a ring, and each R 4 independently represents a hydrogen atom or a methyl group.

5. The modified acrylic block copolymer according to claim 1 , wherein the polymer block (B) further comprises an N-substituted bis((meth)acryl)amide unit (e).

6. The modified acrylic block copolymer according to claim 5 , wherein the N-substituted bis((meth)acryl)amide unit (e) is a unit represented by Formula (II):

in Formula (II), each R 3 independently represents an alkyl group optionally having a substituent, a silyl group, an amino group optionally having a substituent, a silanyl group, an alicyclic group optionally having a substituent, a heterocyclic group optionally having a substituent, or an aromatic ring group optionally having a substituent, and each of R 5 and R 6 independently represents a hydrogen atom or a methyl group.

7. An acrylic adhesive comprising the modified acrylic block copolymer according to claim 1 .

8. The acrylic adhesive according to claim 7 , further comprising a tackifier resin in an amount of not less than 1 part by mass and not more than 400 parts by mass relative to 100 parts by mass of the modified acrylic block copolymer.

9. The acrylic adhesive according to claim 7 , further comprising a plasticizer in an amount of not less than 1 part by mass and not more than 400 parts by mass relative to 100 parts by mass of the modified acrylic block copolymer.

10. An adhesive product comprising an adhesive layer comprising the acrylic adhesive according to claim 7 .

11. A method for producing a modified acrylic block copolymer, the method comprising

subjecting a block copolymer (C) to a reaction in the presence of an amine compound, wherein the block polymer (C) comprises a polymer block (A) comprising a (meth)acrylic acid ester unit (a) and a polymer block (B′) comprising a (meth)acrylic acid ester unit (b′), the (meth)acrylic acid ester unit (a) is structurally different from the (meth)acrylic acid ester unit (b′), thereby partly or entirely converting only the (meth)acrylic acid ester unit (b′) into at least one selected from the group consisting of an N-substituted (meth)acrylamide unit (d), a (meth)acrylic acid unit (c), and an N-substituted bis((meth)acryl)amide unit (e), to obtain the modified acrylic block copolymer comprising the polymer block (A) and a polymer block (B), the polymer block (B) comprising the N-substituted (meth)acrylamide unit (d) and the (meth)acrylic acid unit (c), and the polymer block (B) satisfying the following relationships:

5<([ d]+[c ])<90; and

0.01<[ d]/[c]< 0.075×([ d]+[c ])+4;

wherein

[d] is a molar amount of the N-substituted (meth)acrylamide unit (d) relative to 100 mol of total molar amount of units constituting the polymer block (B) and

[c] is a molar amount of the (meth)acrylic acid unit (c) relative to 100 mol of total molar amount of units constituting the polymer block (B).

12. The method for producing a modified acrylic block copolymer according to claim 11 , wherein the converting is performed by controlling a temperature of a mixture of the block copolymer (C) and the amine compound to be not less than a softening point of the block copolymer (C).

13. The method for producing a modified acrylic block copolymer according to claim 11 , wherein the amine compound is a primary amine or a secondary amine.

14. The method for producing a modified acrylic block copolymer according to claim 11 , wherein the amine compound is a primary amine represented by Formula (1) or a secondary amine represented by Formula (2):

in Formulae (1) and (2), each of R 1 , R 2 and R 3 independently represents an alkyl group optionally having a substituent, a silyl group, an amino group optionally having a substituent, a silanyl group, an alicyclic group optionally having a substituent, a heterocyclic group optionally having a substituent, or an aromatic ring group optionally having a substituent, and R 1 and R 2 together with the nitrogen atom to which they are bound optionally form a ring.

15. The method for producing a modified acrylic block copolymer according to claim 11 , wherein the (meth)acrylic acid ester unit (a) is an alkyl (meth)acrylate unit that is not a methyl (meth)acrylate unit.

16. The method for producing a modified acrylic block copolymer according to claim 11 , wherein the (meth)acrylic acid ester unit (b′) is a methyl (meth)acrylate unit.

17. The method for producing a modified acrylic block copolymer according to claim 11 , wherein a molar amount of the amine compound used in the reaction is 2 mol to 100 mol relative to 100 mol of the (meth)acrylic acid ester unit (b′).