Amine/thiol curing of benzoxazines

1. A curable composition comprising a benzoxazine, a thiol compound of the formula: R 4 —(SH) n , where n is 1 to 6 and R 4 is a (hetero)hydrocarbyl group;

and an amine compound of the formula: R 10 (NHR 9 ) p , wherein R 10 is (hetero)hydrocarbyl group; p is 1 to 6, and each R 9 is H or a hydrocarbyl group, and wherein at least one of said thiol compound and amine compound is polyfunctional and wherein the benzoxazine ring is opened with the thiol compound and the amine compound, wherein

the molar ratio of the sum of the amine and thiol groups to the benzoxazine groups is from 2:1 to 1:10, and the ratio of thiol equivalents to amine equivalents is from 50:1 to 1:5.

2. The curable composition of claim 1 wherein said thiol compound is a polythiol.

3. The curable composition of claim 1 wherein said amine compound is a polyamine.

4. The curable composition of claim 1 comprising a polythiol and polyamine.

5. The curable composition of claim 1 wherein the benzoxazine is a polybenzoxazine.

6. The curable composition of claim 5 wherein the polybenzoxazine is of the formula:

wherein

each of R 1 is H or an alkyl group;

R 2 is H, a covalent bond, or a polyvalent (hetero)hydrocarbyl group;

R 5 is the (hetero)hydrocarbyl residue of a primary amino compound having a valence of x,

m is 2-4; and

x is at least 1.

7. The curable composition of claim 6 wherein R 5 is a poly(alkyleneoxy) group.

8. The curable composition of claim 5 wherein the polbenzoxazine compound is of the formula:

each of R 1 is H or an alkyl group;

R 2 is H, a covalent bond, or a divalent (hetero)hydrocarbyl group;

m is 2-4

R 5 is the (hetero)hydrocarbyl group.

9. The curable composition of claim 5 wherein the polybenzoxazine compound is of the formula:

wherein,

each of R 1 is H or an alkyl group;

R 2 is a covalent bond, or a divalent (hetero)hydrocarbyl group;

m is 2-4;

z is at least 2;

R 5 is the divalent (hetero)hydrocarbyl residue of a primary diamino compound.

10. The curable composition of claim 1 wherein R 4 is a non-polymeric aliphatic, cycloaliphatic, aromatic or alkyl-substituted aromatic moiety having from 1 to 30 carbon atoms and optionally 1 to four catenary heteroatoms of oxygen, nitrogen or sulfur.

11. The curable composition of claim 1 wherein the mixture of amine and thiol compounds is represented by the formula:

R 8 —(ZH) p , where

R 8 is the (hetero)hydrocarbyl group,

Z is a mixture of —S— or —NR 9 , where each R 9 is H or a hydrocarbyl group, including aryl and alkyl, and

p is 1 to 6.