Prepreg, fiber-reinforced composite material, high-pressure gas storage tank, method for producing prepreg, and method for producing high-pressure gas storage tank

A method for producing a prepreg, the method comprising:

• preparing an epoxy resin composition comprising an epoxy resin (A), an epoxy resin curing agent (B) comprising a reaction product (X) of a component (x1) and a component (x2), and a solvent:
• (x1) at least one selected from the group consisting of meta-xylylenediamine and para-xylylenediamine, and
• (x2) at least one selected from the group consisting of unsaturated carboxylic acids represented by General Formula (1) and derivatives thereof;
• (in Formula (1), R1 and R2 each independently represent a hydrogen atom, an alkyl group having from 1 to 8 carbons, an aryl group having from 6 to 12 carbons, or an aralkyl group having from 7 to 13 carbons)
• impregnating reinforcing fibers with the epoxy resin composition to obtain an undried prepreg;
• and
• drying the undried prepreg under conditions satisfying Relational Expression (i), to remove the solvent:
• 8000≤(K×T)/W≤30000••• (i)
• K:
• drying temperature (K)
• T:
• drying time (seconds)
• W:
• thickness (mm) of undried prepreg.

A method for producing a high-pressure gas storage tank comprising a liner and an outer layer formed from a fiber-reinforced composite material, the method comprising, in order:

• preparing an epoxy resin composition comprising an epoxy resin (A), an epoxy resin curing agent (B) comprising a reaction product (X) of a component (x1) and a component (x2), and a solvent:
• (x1) at least one selected from the group consisting of meta-xylylenediamine and para-xylylenediamine, and
• (x2) at least one selected from the group consisting of unsaturated carboxylic acids represented by General Formula (1) and derivatives thereof;
• (in Formula (1), R1 and R2 each independently represent a hydrogen atom, an alkyl group having from 1 to 8 carbons, an aryl group having from 6 to 12 carbons, or an aralkyl group having from 7 to 13 carbons)
• impregnating continuous fiber bundles with the epoxy resin composition to obtain an undried tow prepreg;
• drying the undried tow prepreg under conditions satisfying Relational Expression (ia) to remove the solvent and obtain a tow prepreg,
• 8000≤(K×T)/Wa≤30000••• (ia)
• K:
• drying temperature (° C.)
• T:
• drying time (seconds)
• Wa:
• thickness (mm) of undried tow prepreg;
• and
• wrapping the tow prepreg around an outer surface of the liner and then heating to form the outer layer formed from the fiber-reinforced composite material.