Phenalkamine curing agents and epoxy resin compositions containing the same

The present invention relates to a compound according to formula (1) ##STR1## wherein n is 0, 2, 4 or 6 and a, b and c are, independently of one another, 1 or 0. R.sub.1-1a, R.sub.1-1b and R.sub.1-1c are hydrogen, a hydrocarbyl containing 1 to 10 carbon atoms which are alkyl, aryl, alkylene, arylalkyl or alkylaryl or a hydrocarbyl containing 1 to 10 carbon atoms and at least one heteroatom which can be oxygen, sulfur or nitrogen. R.sub.2-1a, R.sub.3-1a, R.sub.4-1a, R.sub.5-1a, R.sub.2-1b, R.sub.3-1b, R.sub.4-1b, R.sub.5-1b, R.sub.2-1c, R.sub.3-1c, R.sub.4-1c and R.sub.5-1c hydrogen or C.sub.1 -C.sub.4 alkyl. R.sub.6-1a, R.sub.7-1a, R.sub.6-1b, R.sub.7-1b, R.sub.6-1c and R.sub.7-1c are C.sub.1 -C.sub.4 akyl. A is an aromatic or alicyclic ring having 5 to 7 carbon atoms. The present invention further relates to a Mannich base reaction product obtained by combining an extract from cashew nutshell liquid with at least one aromatic or alicylic polyamine and at least one aldehyde compound, epoxy resin compositions and curable formulations containing the same, and methods for using such compositions.

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We claim:

1. A compound according to formula (1) ##STR14##

wherein

n is 0, 2, 4 or 6,

a, b and c are, independently of one another, 1 or 0, with the proviso that at least one of a, b or c is 1,

R.sub.1-1a, R.sub.1-1b and R.sub.1-1c are, independently of one another, hydrogen, a hydrocarbyl containing 1 to 10 carbon atoms which are alkyl, aryl, alkylene, arylalkyl or alkylaryl or a hydrocarbyl containing 1 to 10 carbon atoms and at leastone heteroatom which can be oxygen, sulfur or nitrogen;

R.sub.2-1a, R.sub.3-1a, R.sub.4-1a, R.sub.5-1a, R.sub.2-1b, R.sub.3-1b, R.sub.4-1b, R.sub.5-1b, R.sub.2-1c, R.sub.3-1c, R.sub.4-1c and R.sub.5-1c are independently of one another, hydrogen or C.sub.1 -C.sub.4 alkyl,

R.sub.6-1a, R.sub.7-1a, R.sub.6-1b, R.sub.7-1b, R.sub.6-1c and R.sub.7-1c are, independently of one another C.sub.1 -C.sub.4 akyl; and

A is an aromatic or alicyclic ring having 5 to 7 carbon atoms.

2. A compound according to claim 1 wherein R.sub.1-1a, R.sub.1-1b and R.sub.1-1c are, independently of one another, hydrogen, methyl or ethyl, and a, b and c, independently of one another, are 1 or 0, with the proviso that at least one of a, bor c is 1.

3. A compound according to claim 1 wherein R.sub.1-1a is hydrogen, a is 1 and b and c are 0.

4. A compound according to claim 1 wherein R.sub.2-1a, R.sub.3-1a, R.sub.4-1a, R.sub.5-1a, R.sub.2-1b, R.sub.3-1b, R.sub.4-1b, R.sub.5-1b, R.sub.2-1c, R.sub.3-1c, R.sub.4-1c and R.sub.5-1c are, independently of one another, hydrogen, methyl orethyl, and a, b and c, independently of one another, are 1 or 0, with the proviso that at least one of a, b or c is 1.

5. A compound according to claim 4 wherein R.sub.2-1a, R.sub.3-1a, R.sub.4-1a, and R.sub.5-1a are each hydrogen, a is 1 and b and c are 0.

6. A compound according to claim 3 wherein R.sub.2-1a, R.sub.3-1a, R.sub.4-1a, and R.sub.5-1a are each hydrogen, a is 1 and b and c are 0.

7. A compound according to claim 1 wherein R.sub.6-1a, R.sub.7-1a, R.sub.6-1b, R.sub.7-1b, R.sub.6-1c and R.sub.7-1c are, independently of one another, methyl or ethyl, and a, b and c, independently of one another, are 1 or 0, with the provisothat at least one of a, b or c is 1.

8. A compound according to claim 6 wherein R.sub.6-1a and R.sub.7-1a are methyl or ethyl, a is 1 and b and c are 0.

9. A compound according to claim 1 wherein A is an aromatic or alicyclic ring having 6 carbon atoms.

10. A compound according to claim 8 wherein A is an aromatic or alicylic ring having 6 carbon atoms.

11. A compound according to claim 1 represented by formulae (1a) or (1b): ##STR15##

wherein n, a, b and c have been defined above.

12. A Mannich base reaction product obtained by combining an extract from cashew nutshell liquid with at least one aromatic or alicylic polyamine and at least one aldehyde compound.

13. A Mannich base reaction product according to claim 12 wherein the extract cashew nutshell liquid contains a major portion of cardanol (I) and a minor amount of cardol (II) ##STR16##

where n is 0, 2, 4 or 6.

14. A Mannich base reaction product according to claim 13 wherein the extract cashew nutshell liquid contains cardanol (I) and of cardol (II) in a weight ratio of about 90:10 to about 98:2.

15. A Mannich base reaction product according to claim 13 obtained by combining the extract and the at least one aldehyde compound with a polyamine selected from xylenediamine, 1,3-bis(aminomethyl)cyclohexane, and mixtures thereof.

16. A Mannich base reaction product according to claim 15 comprising at least one compound represented by structural formulae (1a) or (1b): ##STR17##

wherein n has been defined above, a, b and c, are, independently of one another, 1 or 0, and an average value for the sum of (a+b+c) is about 1.2 for all of the compounds corresponding to formulae (1a) and/or (1b) in said Mannich base reactionproduct mixture.

17. An epoxy resin composition comprising:

a) a compound according to claim 1 and

b) an epoxy resin having on average more than one glycidyl group per molecule.

18. An epoxy resin composition comprising:

a) a Mannich base reaction product according to claim 16 and

b) an epoxy resin having on average more than one glycidyl group per molecule.

19. A curable formulation comprising:

a) an epoxy resin composition according to claim 17 and

b) a pigment.

20. A curable formulation comprising:

a) an epoxy resin composition according to claim 18 and

b) a pigment.

21. A method for coating a surface having reduced yellowness index using a phenalkamine-containing composition that comprises applying a curable formulation according to claim 19 to the surface.

22. A method for coating a surface having reduced yellowness index using a phenalkamine-containing composition that comprises applying a curable formulation according to claim 20 to the surface.