The use of a sulfonated polyaryl ether ketone or of a sulfonated non-polymeric aryl ether ketone as a dispersant for a polyaryl ether ketone resin powder in an aqueous solution, and also to a corresponding composition, and to a process for preparing a semifinished product comprising a polyaryl ether ketone resin and reinforcing fibers.

The use of a sulfonated polyaryl ether ketone or of a sulfonated non-polymeric aryl ether ketone as a dispersant for a polyaryl ether ketone resin powder in an aqueous solution, and also to a corresponding composition, and to a process for preparing a semifinished product comprising a polyaryl ether ketone resin and reinforcing fibers.

A fiber reinforced resin base material is formed by impregnating a continuous reinforcing fiber(s) or a reinforcing fiber material having a discontinuous fiber(s) dispersed therein with a resin composition which exhibits a single glass-transition temperature before and after being heated at 400° C. for one hour, wherein the resin composition is composed of (A) a thermoplastic resin having a glass-transition temperature of 100° C. or more and (B) a thermoplastic resin having a glass-transition temperature of less than 100° C.

The fiber reinforced resin base material has excellent impregnation properties and thermal stability, having fewer voids, and having surface quality and high heat resistance.