Curable composition with high fracture toughness
A curable composition including an epoxy resin, an open-chain polyamine, and a compound of the formula (I); a hardened composition prepared by curing the curable composition; a process for coating a surface or impregnating a textile sheet, including applying and hardening the curable composition; and a surface, a fiber composite material, a coating, or an adhesive including the hardened composition,
1. A curable composition, comprising:
an epoxy resin;
an open-chain polyamine having at least two primary amine groups on an aliphatic main chain having a carbon chain consisting of carbon atoms and hydrogen atoms; and
a compound of the formula (I)
wherein the moieties R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 19 and R 20 respectively and mutually independently are selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl and amine,
with the proviso that at least one moiety from the group consisting of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 and R 10 is amine and at least one moiety from the group consisting of R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 19 and R 20 is amine.
2. A method of curing the curable composition of claim 1 , the method comprising:
hardening or curing the epoxy resin with a hardener combination comprising the open-chain polyamine and the compound of the formula (I).
3. The curable composition according to claim 1 , wherein precisely one moiety from the group consisting of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 and R 10 is amine and precisely one moiety from the group consisting of R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 19 and R 20 is amine.
4. The curable composition according to claim 1 , wherein precisely one moiety from the group consisting of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 and R 10 is amine and precisely one moiety from the group consisting of R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 19 and R 20 is amine and every other moiety is hydrogen.
5. The curable composition according to claim 1 , wherein the compound of the formula (I) is diaminodicyclohexylmethane.
6. The curable composition according to claim 1 , wherein the open-chain polyamine has a substituted or unsubstituted carbon chain having a total length of from four to eight carbon atoms.
7. The curable composition according to claim 1 , wherein the open-chain polyamine has the formula H 2 N—(CH 2 ) z —NH 2 in which z is from 2 to 12.
8. The curable composition according to claim 1 , wherein the open-chain polyamine is hexamethylenediamine or trimethylhexamethylenediamine.
9. The curable composition according to claim 1 , wherein a ratio by weight of the compound of the formula (I) to the open-chain polyamine is at least 50:50.
10. The curable composition according to claim 9 , wherein a ratio by weight of the compound of the formula (I) to the open-chain polyamine is from 70:30 to 90:10.
11. The curable composition according to claim 1 , wherein the epoxy resin is at least one selected from the group consisting of bisphenol A diglycidyl ether and bisphenol F diglycidyl ether.
12. The curable composition according to claim 1 , further comprising:
at least one further substance selected from the group consisting of a reaction accelerator, a reactive diluent, a solvent, a pigment, a filler, a flame retardant, and an additive.
13. The curable composition according to claim 1 , further comprising:
a reactive diluent,
wherein a ratio by weight of the epoxy resin to the reactive diluent is from 75:25 to 95:5.
14. A process for coating a surface or impregnating a textile sheet, comprising:
applying the curable composition according to claim 1 to the surface or the textile sheet; and
hardening the curable composition.
15. A curable composition according to claim 1 , wherein the epoxy resin has two epoxy groups per molecule.
16. A hardened composition, obtained by curing the curable composition according to claim 1 .
17. A surface, fibre composite material, coating or adhesive, comprising:
the hardened composition according to claim 16 .
18. The curable composition according to claim 1 ,
wherein the epoxy resin comprises bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, or both,
the open-chain polyamine comprises hexamethylenediamine, trimethylhexamethylenediamine, or both, and
the compound of the formula (I) comprises diaminodicyclohexylmethane.
19. The curable composition according to claim 18 , wherein a ratio by weight of the compound of the formula (I) to the open-chain polyamine is from 70:30 to 90:10.
20. The curable composition according to claim 18 , wherein a ratio by weight of the compound of the formula (I) to the open-chain polyamine is from 70:30 to 80:20.
21. The curable composition according to claim 1 , wherein a ratio by weight of the compound of the formula (I) to the open-chain polyamine is from 70:30 to 80:20, and an amount of the epoxy resin is from 381 to 416 parts by weight with respect to 100 parts by weight of a combination of the open-chain polyamine and the compound of the formula (I).
22. The curable composition according to claim 1 , wherein the curable composition is capable of curing at 120° C. for 30 minutes to a cured composition having a fracture toughness of at least 0.9 and a glass transition temperature of at least 129° C.