Prepreg and method of producing a fiber-reinforced composite material

Abstract

A prepreg may include: a reinforcing fiber material including carbon fibers; and a resin composition with which the reinforcing fiber material is impregnated. The resin composition may include an epoxy resin (A), an amine curing agent (B), and an imidazole curing agent (C). The amine curing agent (B) may be present in a range of from 1 to 3.8 parts by mass, relative to 100 parts by mass of the epoxy resin (A). The amine curing agent (B) and the imidazole curing agent (C) may be present in a total amount of not more than 10 parts by mass, relative to 100 parts by mass of the epoxy resin (A). The imidazole curing agent may include an imidazole compound including, in its molecular structure, a triazine ring.

1 : A prepreg, comprising:
 a reinforcing fiber material comprising carbon fibers; and   a resin composition with which the reinforcing fiber material is impregnated,   wherein the resin composition comprises an epoxy resin (A), an amine curing agent (B), and an imidazole curing agent (C),   wherein the resin composition comprises the amine curing agent (B) in a range of from 1 to 3.8 parts by mass, relative to 100 parts by mass of the epoxy resin (A),   wherein the resin composition comprises the amine curing agent (B) and the imidazole curing agent (C) in a total amount of not more than 10 parts by mass, relative to 100 parts by mass of the epoxy resin (A), and   wherein the imidazole curing agent comprises an imidazole compound comprising, in its molecular structure, a triazine ring.   
     
     
         2 : The prepreg of  claim 1 , wherein the amine curing agent (B) comprises dicyandiamide. 
     
     
         3 : The prepreg of  claim 1 , wherein, in the resin composition, the imidazole curing agent (C) is present in a range of from 1 to 3.5 times an amount of the amine curing agent (B) in terms of a mass. 
     
     
         4 : The prepreg of  claim 1 , wherein the resin composition comprises the amine curing agent (B) and the imidazole curing agent (C) in a total amount of not less than 5 parts by mass, relative to 100 parts by mass of the epoxy resin (A). 
     
     
         5 : The prepreg of  claim 1 , wherein the epoxy resin (A) has an epoxy equivalent of not less than 200 g/eq. 
     
     
         6 : The prepreg of  claim 1 , wherein the imidazole curing agent (C) comprises 2,4-diamino-6-(2′-methylimidazolyl-(1′))-ethyl-s-triazine. 
     
     
         7 : The prepreg of  claim 1 , wherein the amine curing agent (B) is dicyandiamide, and
 wherein the imidazole curing agent (C) is 2,4-diamino-6-(2′-methylimidazolyl-(1′))-ethyl-s-triazine.   
     
     
         8 : The prepreg of  claim 1 , wherein a curing completion time of the resin composition measured with use of a CURELASTOMETER® system is less than or equal to 5 minutes at 140° C. 
     
     
         9 : The prepreg of  claim 1 , wherein the reinforcing fiber material is impregnated with the resin composition to a degree of impregnation of not less than 98%. 
     
     
         10 : The prepreg of  claim 1 , wherein the prepreg yields a value in a range of from 20 to 70° in a test on drape properties. 
     
     
         11 : The prepreg of  claim 1 , wherein the prepreg is a cloth prepreg. 
     
     
         12 : A method of producing a fiber-reinforced composite material, the method comprising:
 curing the prepreg of  claim 1  with a mold, at a temperature in a range of from 100 to 180° C., for a time period in a range of from 1 to 15 minutes.   
     
     
         13 : The prepreg of  claim 1 , wherein the reinforcing fiber material is made of carbon fibers.