Epoxy resin composition, prepreg, and fiber-reinforced composite material

1. An epoxy resin composition comprising:

at least one reactive diluent [A] having a viscosity of 2 Pas or less at 25° C. and selected from the group consisting of a reactive diluent having a structure represented by general formula (4), a reactive diluent having a structure represented by general formula (7), and a reactive diluent having a structure represented by general formula (8);

at least one trifunctional or higher functional epoxy resin [B] selected from the group consisting of N,N,O-triglycidyl-m-aminophenol, N,N,O-triglycidyl-p-aminophenol, N,N,O-triglycidyl-4-amino-3-methylphenol, N,N,N′,N′-tetraglycidyl-4,4′-methylenedianiline, N,N,N′,N′-tetraglycidyl-2,2′-diethyl-4,4′-methylenedianiline and N,N,N′,N′-tetraglycidyl-m-xylylenediamine;

at least one amine-based hardener [C] selected from the group consisting of an amine-based hardener having a structure represented by general formula (2) and an amine-based hardener having a structure represented by general formula (3);

optionally, a non-phosphorus-containing aromatic polyamine hardener provided in an amount of up to 90 parts by mass based on 100 parts by mass total of [C] and the aromatic polyamine hardener; and

at least one thermoplastic resin [D] composed of a polyaryl ether skeleton:

wherein in the general formula (4), R 3 and R 4 each independently represent at least one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group with a carbon number of 1 to 4, an alicyclic hydrocarbon group with a carbon number of 3 to 6, an aromatic hydrocarbon group with a carbon number of 6 to 10, a halogen atom, an acyl group, a trifluoromethyl group and a nitro group; and X 3 represents one selected from the group consisting of —O—, —S—, —CO—, —C(═O)O— and —S 2− ;

wherein in the general formula (7), R 7 and R 8 each independently represent at least one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group with a carbon number of 1 to 4, an alicyclic hydrocarbon group with a carbon number of 3 to 6, an aromatic hydrocarbon group with a carbon number of 6 to 10, a halogen atom, an acyl group, a trifluoromethyl group and a nitro group, with the proviso that both of R 7 and R 8 are not hydrogen atoms;

wherein in the general formula (8), R 9 and R 10 each independently represent a direct bond, an alkylene group with a carbon number of 1 to 8, a phenylene group or a cyclohexylene group; and R 11 represents one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group with a carbon number of 1 to 4, an alicyclic hydrocarbon group with a carbon number of 3 to 6, an aromatic hydrocarbon group with a carbon number of 6 to 10, a halogen atom, an acyl group, a trifluoromethyl group and a nitro group;

wherein in the general formula (2), R 1 represents a hydrocarbon group with a carbon number of 2 to 4; and in the general formula (3), R 2 represents a hydrogen atom or an amino group;

wherein [A] is present in an amount of 10 to 50 parts by mass and [B] is present in an amount of 50 to 90 parts by mass, totaling 100 parts by mass; and

wherein [C] is present in amount to provide a phosphorus atom content of 1.0 to 5.0% by mass, based on the overall mass of the epoxy resin composition.

2. The epoxy resin composition according to claim 1 , wherein [A] comprises a reactive diluent having a structure represented by general formula (4) or a reactive diluent having a structure represented by general formula (7).

3. The epoxy resin composition according to claim 1 , wherein R 3 and R 4 of the general formula (4) is a hydrogen atom.

4. The epoxy resin composition according to claim 1 , wherein at least one of R 7 and R 8 of the general formula (7) is a methyl group.

5. The epoxy resin composition according to claim 1 , wherein [A] is selected from the group consisting of N,N-diglycidyl-4-phenoxyaniline, N,N-diglycidyl-o-toluidine, N,N-diglycidyl-m-toluidine, N,N-diglycidyl-p-toluidine, N,N-diglycidyl-2,3-xylidine, N,N-diglycidyl-2,4-xylidine, N,N-diglycidyl-3,4-xylidine, 1,4-cyclohexanedimethanol diglycidyl ether, and 1,4-cyclohexanediethanol diglycidyl ether.

6. The epoxy resin composition according to claim 1 , wherein [A] is present in an amount of 20 to 40 parts by mass and [B] is present in an amount of 60 to 80 parts by mass, totaling 100 parts by mass.

7. The epoxy resin composition according to claim 1 , wherein [C] comprises an amine-based hardener having a structure represented by general formula (3).

8. The epoxy resin composition according to claim 7 , wherein R 2 in the general formula (3) is an amino group.

9. The epoxy resin composition according to claim 1 , wherein [D] comprises polyethersulfone.

10. The epoxy resin composition according to claim 9 , wherein [D] is present in amount of 24 to 27 parts by mass based on the total 100 parts by mass of [A] and [B].

11. The epoxy resin composition according to claim 1 , wherein the optional aromatic polyamine hardener is not present, and the epoxy resin composition has a viscosity increase ratio after 2 hours at 80° C. of 7% to 30%, and a cured product of the epoxy resin composition has a flexural modulus of 4.1 to 4.5 GPa and a char production ratio at 650° C. of 25% to 30%.

12. The epoxy resin composition according to claim 1 , wherein the optional aromatic polyamine hardener is present and is 3,3′-diaminodiphenyl sulfone.

13. The epoxy resin composition according to claim 12 , wherein the epoxy resin composition has a viscosity increase ratio after 2 hours at 80° C. of 12% to 47%, and a cured product of the epoxy resin composition has a flexural modulus of 3.8 to 4.8 GPa and a char production ratio at 650° C. of 9% to 17%.

14. A prepreg obtained by impregnating a reinforced fiber with the epoxy resin composition described in claim 1 .

15. A fiber-reinforced composite material obtained by curing the prepreg described in claim 14 .

16. A fiber-reinforced composite material comprising a cured resin obtained by curing the epoxy resin composition described in claim 1 , and a reinforced fiber.

17. An epoxy resin composition comprising

a difunctional glycidyl amine epoxy resin [A′] represented by general formula (4);

at least one trifunctional or higher functional epoxy resin [B] selected from the group consisting of N,N,O-triglycidyl-m-aminophenol, N,N,O-triglycidyl-p-aminophenol, N,N,O-triglycidyl-4-amino-3-methylphenol, N,N,N′,N′-tetraglycidyl-4,4′-methylenedianiline, N,N,N′,N′-tetraglycidyl-2,2′-diethyl-4,4′-methylenedianiline and N,N,N′,N′-tetraglycidyl-m-xylylenediamine;

at least one amine-based hardener [C] selected from the group consisting of an amine-based hardener having a structure represented by general formula (5) and an amine-based hardener having a structure represented by general formula (6);

optionally, a non-phosphorus-containing aromatic polyamine hardener provided in an amount of up to 90 parts by mass based on 100 parts by mass total of [C′] and the aromatic polyamine hardener; and

at least one thermoplastic resin [D] composed of a polyaryl ether skeleton:

wherein in the general formula (4), R 3 and R 4 each independently represent at least one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group with a carbon number of 1 to 4, an alicyclic hydrocarbon group with a carbon number of 3 to 6, an aromatic hydrocarbon group with a carbon number of 6 to 10, a halogen atom, an acyl group, a trifluoromethyl group and a nitro group; and X 3 represents one selected from the group consisting of —O—, —S—, —CO—, —C(═O)O— and —SO 2− ;

wherein in the general formula (5), R 5 represents a hydrocarbon group with a carbon number of 1 to 4; and in general formula (6), R 6 represents a hydrogen atom or an amino group;

wherein [A] is present in an amount of 10 to 50 parts by mass and [B] is present in an amount of 50 to 90 parts by mass, totaling 100 parts by mass; and

wherein [C] is present in amount to provide a phosphorus atom content of 1.0 to 5.0% by mass, based on the overall mass of the epoxy resin composition.

18. The epoxy resin composition according to claim 17 , wherein R 3 and R 4 of the general formula (4) is a hydrogen atom.

19. The epoxy resin composition according to claim 17 , wherein [C′] comprises an amine-based hardener having a structure represented by general formula (6).

20. The epoxy resin composition according to claim 19 , wherein R 6 in the general formula (6) is an amino group.

21. The epoxy resin composition according to claim 17 , wherein [D] comprises polyethersulfone.

22. The epoxy resin composition according to claim 21 , wherein [D] is present in amount of 24 to 27 parts by mass based on the total 100 parts by mass of [A] and [B].

23. The epoxy resin composition according to claim 17 , wherein the optional aromatic polyamine hardener is not present, the epoxy resin composition has a viscosity increase ratio after 2 hours at 80° C. of 7% to 30%, and a cured product of the epoxy resin composition has a flexural modulus of 4.1 to 4.5 GPa and a char production ratio at 650° C. of 25% to 30%.

24. The epoxy resin composition according to claim 17 , wherein the optional aromatic polyamine hardener is present and is 3,3′-diaminodiphenyl sulfone.

25. The epoxy resin composition according to claim 24 , wherein the epoxy resin composition has a viscosity increase ratio after 2 hours at 80° C. of 13% to 47%, and a cured product of the epoxy resin composition has a flexural modulus of 4.3 to 4.6 GPa and a char production ratio at 650° C. of 11% to 17%.

26. A prepreg obtained by impregnating a reinforced fiber with the epoxy resin composition described in claim 17 .

27. A fiber-reinforced composite material obtained by curing the prepreg described in claim 26 .

28. A fiber-reinforced composite material comprising a cured resin obtained by curing the epoxy resin composition described in claim 17 , and a reinforced fiber.