Epoxy resin composition for fiber-reinforced composite material, method for producing epoxy resin composition for fiber-reinforced composite material, prepreg, and honey-comb panel

1. An epoxy resin composition for a fiber-reinforced composite material comprising:

a reaction product obtained by reacting 100 parts by mass of a phosphorus-containing epoxy resin containing a phosphorus atom in a backbone thereof, and not less than 5 parts by mass and not greater than 20 parts by mass of an amino-terminated liquid rubber;

an epoxy resin different than the phosphorus-containing epoxy resin;

a curing agent; and

a curing accelerator; wherein:

a compounded amount of the phosphorus-containing epoxy resin is not less than 50 parts by mass and not greater than 95 parts by mass per 100 parts by mass of a total amount of the phosphorus-containing epoxy resin and the epoxy resin different than the phosphorus-containing epoxy resin;

a compounded amount of the phosphorus-containing epoxy resin is not less than 30 mass % and not greater than 80 mass % with respect to the total mass of the epoxy resin composition; and

the phosphorus-containing epoxy resin has lower reactivity than that of the epoxy resin different than the phosphorus-containing epoxy resin, and the reaction product has crosslinking as a result of the reaction between the phosphorus-containing epoxy resin and the amino-terminated liquid rubber.

2. The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the amino-terminated liquid rubber is an amino-terminated butadiene-acrylonitrile rubber.

3. The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the curing accelerator contains at least one type selected from the group consisting of phenylurea-based compounds represented by Formula (1):

where R 1 is a phenyl group and R 2 and R 3 are alkyl groups.

4. The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the curing agent is dicyandiamide.

5. The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein a phosphorus content of the phosphorus-containing epoxy resin is not less than 0.5 mass % and not greater than 5.0 mass %.

6. The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein a content of the curing accelerator is not less than 1 part by mass and not greater than 15 parts by mass per 100 parts by mass of a sum of a mass of the phosphorus-containing epoxy resin and a mass of the other epoxy resin.

7. The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , further comprising a phenoxy resin.

8. The epoxy resin composition for a fiber-reinforced composite material according to claim 7 , wherein a content of the phenoxy resin is not less than 5 parts by mass and not greater than 40 parts by mass per 100 parts by mass of a sum of a mass of the phosphorus-containing epoxy resin and a mass of the other epoxy resin.

9. A method for producing an epoxy resin composition for a fiber-reinforced composite material, the method comprising:

reacting 100 parts by mass of a phosphorus-containing epoxy resin containing a phosphorus atom in a backbone thereof and not less than 5 parts by mass and not greater than 20 parts by mass of an amino-terminated liquid rubber for not less than 10 minutes and not greater than 3 hours at a reaction temperature of not lower than 100° C. and not higher than 200° C. to obtain a reaction product; and

mixing the reaction product, an epoxy resin different than the phosphorus-containing epoxy resin, a curing agent, and a curing accelerator to obtain an epoxy resin composition for a fiber-reinforced composite material wherein a compounded amount of the phosphorus-containing epoxy resin is not less than 50 parts by mass and not greater than 95 parts by mass per 100 parts by mass of a total amount of the phosphorus-containing epoxy resin and the epoxy resin different than the phosphorus-containing epoxy resin; a compounded amount of the phosphorus-containing epoxy resin is not less than 30 mass % and not greater than 80 mass % with respect to the total mass of the epoxy resin composition; and the phosphorus-containing epoxy resin has lower reactivity than that of the epoxy resin different than the phosphorus-containing epoxy resin, and the reaction product has crosslinking as a result of the reaction between the phosphorus-containing epoxy resin and the amino-terminated liquid rubber.

10. A prepreg obtained by impregnating a reinforced fiber with the epoxy resin composition for a fiber-reinforced composite material according to claim 1 .

11. A honeycomb panel obtained by laminating and curing the prepreg according to claim 10 and a honeycomb core.

12. The honeycomb panel according to claim 11 , wherein the honeycomb core is at least one type selected from the group consisting of an aramid honeycomb, an aluminum honeycomb, a paper honeycomb, and a glass honeycomb.

13. The epoxy resin composition for a fiber-reinforced composite material according to claim 2 , wherein the curing accelerator contains at least one type selected from the group consisting of phenylurea-based compounds represented by Formula (1):

where R 1 is a phenyl group and R 2 and R 3 are alkyl groups.

14. The epoxy resin composition for a fiber-reinforced composite material according to claim 13 , wherein the curing agent is dicyandiamide.

15. The epoxy resin composition for a fiber-reinforced composite material according to claim 14 , wherein a phosphorus content of the phosphorus-containing epoxy resin is not less than 0.5 mass % and not greater than 5.0 mass %.

16. The epoxy resin composition for a fiber-reinforced composite material according to claim 15 , wherein a content of the curing accelerator is not less than 1 part by mass and not greater than 15 parts by mass per 100 parts by mass of a sum of a mass of the phosphorus-containing epoxy resin and a mass of the other epoxy resin.

17. The epoxy resin composition for a fiber-reinforced composite material according to claim 16 , further comprising a phenoxy resin.

18. The epoxy resin composition for a fiber-reinforced composite material according to claim 17 , wherein a content of the phenoxy resin is not less than 5 parts by mass and not greater than 40 parts by mass per 100 parts by mass of a sum of a mass of the phosphorus-containing epoxy resin and a mass of the other epoxy resin.

19. A prepreg obtained by impregnating a reinforced fiber with the epoxy resin composition for a fiber-reinforced composite material according to claim 18 .

20. A honeycomb panel obtained by laminating and curing the prepreg according to claim 19 and a honeycomb core, wherein the honeycomb core is at least one type selected from the group consisting of an aramid honeycomb, an aluminum honeycomb, a paper honeycomb, and a glass honeycomb.