Epoxy resin composition, and film, prepreg, and fiber-reinforced plastic using same

1. An epoxy resin composition, comprising an epoxy resin and a curing agent, and satisfying the following (1), (2), and (3):

(1) a bending elastic modulus of a cured product of the epoxy resin composition is 3.3 GPa or higher;

(2) a bending strain at break of the cured product of the epoxy resin composition is 9% or higher; and

(3) a fiber-reinforced plastic a formed of the cured product of the epoxy resin composition and a reinforcing fiber substrate in which carbon fibers, which are continuous fibers, are evenly aligned in one direction has 90° bending strength of 95 MPa or higher,

wherein the epoxy resin comprises:

(A) an oxazolidone ring-containing epoxy resin, which is not a glycidylamine epoxy resin, in an amount of 30 parts by mass to 70 parts by mass;

(B-1) a glycidylamine epoxy resin not having an oxazolidone ring in an amount of 1 part by mass to 30 parts by mass;

(C) a bisphenol bifunctional epoxy resin having the number average molecular weight of 600 or more, which does not have oxazolidone ring and is not a glycidylamine epoxy resin, in an amount of 5 parts by mass to 30 parts by mass;

(D) a phenoxy resin in an amount of 1 part by mass to 15 parts by mass; and

(E) a curing agent in an amount of 1 part by mass to 25 parts by mass,

each of the amounts of (A), (B-1) , (C), (D), and (E) being relative to 100 parts by mass of a total amount of all epoxy resins contained in the epoxy resin composition.

2. The epoxy resin composition according to claim 1 , wherein the 90° bending strain at break of the fiber-reinforced plastic α is 1.3% or higher.

3. A film, comprising the epoxy resin composition according to claim 1 .

4. The epoxy resin composition according to claim 1 , further comprising:

(G) a low viscosity epoxy resin, which does not contain an oxazolidone ring and is neither a diglycidylamine epoxy resin nor glycidylphthalimide,

wherein a total amount of the components (A), (B-1) , (C), and (G) is 75 parts by mass or more relative to 100 parts by mass of the total amount of the epoxy resin contained in the epoxy resin composition.

5. The epoxy resin composition according to claim 1 , wherein the epoxy resin composition further satisfies the following (4):

(4) a tensile lap-shear strength is 9.5 MPa or higher when measurement is made based on JIS K 6850 by using A5052 aluminum as a subject for adhesion.

6. The epoxy resin composition according to claim 1 , wherein the component (B-1) is glycidylaniline.

7. The epoxy resin composition according to claim 1 , wherein the component (B-1) is N,N-diglycidyl-o-toluidine.

8. The epoxy resin composition according to claim 1 , wherein a number average molecular weight of the component (B-1) is 300 or less.

9. A prepreg comprising a reinforcing fiber substrate and the epoxy resin composition according to claim 1 impregnated in the reinforcing fiber substrate.

10. A fiber-reinforced plastic, comprising a cured product of the epoxy resin composition according to claim 1 and a reinforcing fiber.

11. The fiber-reinforced plastic according to claim 10 having a tubular shape.

12. An epoxy resin composition, comprising an epoxy resin and a curing agent, and satisfying the following (1), (2), and (3):

(1) the bending elastic modulus of a cured product of the epoxy resin composition is 3.3 GPa or higher;

(2) the bending strain at break of the cured product of the epoxy resin composition is 9% or higher; and

(3) the fiber-reinforced plastic a formed of the cured product of the epoxy resin composition and a reinforcing fiber substrate in which carbon fibers, which are continuous fibers, are evenly aligned in one direction has 90° bending strength of 95 MPa or higher,

wherein the epoxy resin comprises:

(A) an oxazolidone ring-containing epoxy resin, which is not a glycidylamine epoxy resin, in an amount of 30 parts by mass to 70 parts by mass;

(B-2) glycidylphthalimide in an amount of 1 part by mass to 15 parts by mass;

(C) a bisphenol bifunctional epoxy resin having the number average molecular weight of 600 or more, which does not have an oxazolidone ring and is not a glycidylamine epoxy resin, in an amount of 5 parts by mass to 30 parts by mass;

(D) a phenoxy resin in an amount of 1 part by mass to 15 parts by mass; and

(E) a curing agent in an amount of 1 part by mass to 25 parts by mass,

each of the amounts of (A), (B-2), (C), (D), and (E) being relative to 100 parts by mass of a total amount of all epoxy resins contained in the epoxy resin composition.

13. The epoxy resin composition according to claim 12 , wherein the 90° bending strain at break of the fiber-reinforced plastic a is 1.3% or higher.

14. A film, comprising the epoxy resin composition according to claim 12 .

15. The epoxy resin composition according to claim 12 , further comprising:

(G) a low viscosity epoxy resin, which does not contain an oxazolidone ring and is neither a diglycidylamine epoxy resin nor glycidylphthalimide,

wherein a total amount of the components (A), (B-2), (C), and (G) is 75 parts by mass or more relative to 100 parts by mass of the total amount of the epoxy resin contained in the epoxy resin composition.

16. A prepreg comprising a reinforcing fiber substrate and the epoxy resin composition according to claim 12 impregnated in the reinforcing fiber substrate.

17. A fiber-reinforced plastic, comprising a cured product of the epoxy resin composition according to claim 12 and a reinforcing fiber.

18. The fiber-reinforced plastic according to claim 17 having a tubular shape.