Two-part curable urethane adhesive composition

1. A two-part curable urethane adhesive composition comprising:

a main agent (A) containing a urethane prepolymer (a); and

a curing agent (B) containing a compound having two or more active hydrogen groups per molecule (b);

wherein the compound having active hydrogen groups (b) comprises a tri- or higher functional polyol compound with a molecular weight of 1000 or less (b1); and

one or both of the main agent (A) and the curing agent (B) further contain a terpene oligomer (x).

2. The two-part curable urethane adhesive composition according to claim 1 , wherein a content of the polyol compound (b1) in the compound having active hydrogen groups (b) is from 0.5 mass % to 25.0 mass % of the compound having active hydrogen groups (b).

3. The two-part curable urethane adhesive composition according to claim 1 , wherein a hydroxyl value of the polyol compound (b1) is not less than 250 mg KOH/g.

4. The two-part curable urethane adhesive composition according to claim 1 , wherein the polyol compound (b1) is a tetra- or higher functional polyol compound with a molecular weight of 1000 or less.

5. The two-part curable urethane adhesive composition according to claim 1 , wherein the compound having active hydrogen groups (b) further comprises at least one type of polyol compound selected from the group consisting of a bifunctional polyol compound (b2) and a tri- or higher functional polyol compound with a molecular weight greater than 1000 (b3).

6. The two-part curable urethane adhesive composition according to claim 5 , wherein a total content of the polyol compound (b1) and the at least one type of polyol compound selected from the group consisting of the polyol compound (b2) and the polyol compound (b3) in the compound having active hydrogen groups (b) is not less than 50.0 mass % of the compound having active hydrogen groups (b).

7. The two-part curable urethane adhesive composition according to claim 1 , wherein one or both of the main agent (A) and the curing agent (B) further contain a silane compound (y).

8. The two-part curable urethane adhesive composition according to claim 1 , wherein the terpene oligomer (x) is at least one type selected from the group consisting of a compound represented by Formula (8), a compound represented by Formula (9), and a compound represented by Formula (10):

wherein, in Formulas (8) to (10), m is an integer satisfying 2≤m≤6; n is an integer satisfying 1≤n≤3; a product of m and n, m×n, satisfies 2≤m×n≤6; and in Formula (10), R represents a hydrogen atom or an alkyl group having from 1 to 12 carbons.

9. The two-part curable urethane adhesive composition according to claim 2 , wherein a hydroxyl value of the polyol compound (b1) is not less than 250 mg KOH/g.

10. The two-part curable urethane adhesive composition according to claim 2 , wherein the polyol compound (b1) is a tetra- or higher functional polyol compound with a molecular weight of 1000 or less.

11. The two-part curable urethane adhesive composition according to claim 2 , wherein the compound having active hydrogen groups (b) further comprises at least one type of polyol compound selected from the group consisting of a bifunctional polyol compound (b2) and a tri- or higher functional polyol compound with a molecular weight greater than 1000 (b3).

12. The two-part curable urethane adhesive composition according to claim 11 , wherein a total content of the polyol compound (b1) and the at least one type of polyol compound selected from the group consisting of the polyol compound (b2) and the polyol compound (b3) in the compound having active hydrogen groups (b) is not less than 50.0 mass % of the compound having active hydrogen groups (b).

13. The two-part curable urethane adhesive composition according to claim 2 , wherein one or both of the main agent (A) and the curing agent (B) further contain a silane compound (y).

14. The two-part curable urethane adhesive composition according to claim 2 , wherein the terpene oligomer (x) is at least one type selected from the group consisting of a compound represented by Formula (8), a compound represented by Formula (9), and a compound represented by Formula (10):

wherein, in Formulas (8) to (10), m is an integer satisfying 2≤m≤6; n is an integer satisfying 1≤n≤3; a product of m and n, m×n, satisfies 2≤m×n≤6; and in Formula (10), R represents a hydrogen atom or an alkyl group having from 1 to 12 carbons.

15. The two-part curable urethane adhesive composition according to claim 3 , wherein the polyol compound (b1) is a tetra- or higher functional polyol compound with a molecular weight of 1000 or less.

16. The two-part curable urethane adhesive composition according to claim 3 , wherein the compound having active hydrogen groups (b) further comprises at least one type of polyol compound selected from the group consisting of a bifunctional polyol compound (b2) and a tri- or higher functional polyol compound with a molecular weight greater than 1000 (b3).

17. The two-part curable urethane adhesive composition according to claim 16 , wherein a total content of the polyol compound (b1) and the at least one type of polyol compound selected from the group consisting of the polyol compound (b2) and the polyol compound (b3) in the compound having active hydrogen groups (b) is not less than 50.0 mass % of the compound having active hydrogen groups (b).

18. The two-part curable urethane adhesive composition according to claim 3 , wherein one or both of the main agent (A) and the curing agent (B) further contain a silane compound (y).

19. The two-part curable urethane adhesive composition according to claim 3 , wherein the terpene oligomer (x) is at least one type selected from the group consisting of a compound represented by Formula (8), a compound represented by Formula (9), and a compound represented by Formula (10):

wherein, in Formulas (8) to (10), m is an integer satisfying 2≤m≤6; n is an integer satisfying 1≤n≤3; a product of m and n, m×n, satisfies 2≤m×n≤6; and in Formula (10), R represents a hydrogen atom or an alkyl group having from 1 to 12 carbons.