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

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

(a) one or more epoxy resins;

(b) an aromatic diamine compound;

(c) a dicyandiamide;

(d) a urea compound; and

(e) an amine adduct compound,

blended in the following blending proportions:

a blending proportion of the (b) aromatic diamine compound being from 0.2 to 0.6 equivalents relative to the (a) epoxy resin,

a blending proportion of the (c) dicyandiamide being from 0.5 to 4.0 mass % relative to a total of the (a) to (e) components,

a blending proportion of the (d) urea compound being from 0.5 to 2.0 mass % relative to the total of the (a) to (e) components, and

a blending proportion of the (e) amine adduct compound being from greater than 0 mass % to 3.0 mass % relative to the total of the (a) to (e) components, wherein

a glass transition temperature of a cured product is 110° C. or higher, the cured product being obtained by curing the resin composition under curing conditions: at 120° C. and for 1.5 hours, until a state where demolding from a mold can be performed.

2 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the cured product has a glass transition temperature of 180° C. or higher by post-curing at 180° C. for 2 hours.

3 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the (a) epoxy resin comprises from 0 to 80 mass % of a bifunctional epoxy resin and from 20 to 100 mass % of a trifunctional or higher functional epoxy resin.

4 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein a reaction start temperature (exothermic peak onset temperature) according to differential scanning calorimetry (DSC analysis) at a temperature increase rate of 10° C./min is 90° C. or higher and 120° C. or lower.

5 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the (b) aromatic diamine compound is one or more selected from the group consisting of 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 4,4′-methylenebis(2,6-diethylaniline) and 4,4′-methylenebis(2-ethyl-6-methyl)benzeneamine.

6 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the (d) urea compound is one or more selected from the group consisting of 3-(3,4′-dichlorophenyl)-1,1-dimethylurea, 2,4-toluenebisdimethylurea, and 4,4′-methylenebis(phenyldimethylurea).

7 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the blending proportion of the (b) aromatic diamine compound is from 0.3 to 0.5 equivalents relative to the (a) epoxy resin.

8 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the blending proportion of the (c) dicyandiamide is from 1.0 to 3.0 mass % relative to the total of the (a) to (e) components.

9 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the blending proportion of the (d) urea compound is from 0.5 to 1.5 mass % relative to the total of the (a) to (e) components.

10 . The epoxy resin composition for a fiber-reinforced composite material according to claim 1 , wherein the blending proportion of the (e) amine adduct compound is from greater than 0 mass % to 2 mass % relative to the total of the (a) to (e) components.

11 . A prepreg comprising the epoxy resin composition for a fiber-reinforced composite material according to claim 1 , the epoxy resin composition being impregnated into any of glass fiber, quartz fiber, aramid fiber, or carbon fiber.

12 . A fiber-reinforced composite material according to claim 11 , which is a cured product of the prepreg.