Method for preparing preforms for molding processes

Claim 1

A method for preparing preforms which comprises (1) applying substantially evenly onto the surface of each of one or more plys of an unimpregnated substrate material one or more non-sintering thermoplastic-like resinous compounds which are substantially free of any compound which would serve as a crosslinker for said thermoplastic-like, solid resinous compound, said resinous compound being in the form of a powder having a particle size of less than about 500 microns and having a melting point of from about 50° C. to about 70° C. in an amount of from about 2 to about 12 percent by weight based upon the weight of said substrate material; (2) fusing said powdered thermoplastic-like resinous compound into a film on the surface of said substrate material: (3) cooling said resinous material: (4) assembling one or more plies of the thus treated substrate material and conforming said plies of said treated substrate material into a desired shape: (5) subjecting the thus shaped plies of treated substrate material at a temperature sufficient to melt said resinous compound; and (6) cooling said shaped treated plies of substrate material to a temperature below the melting point of said resinous compound; thereby forming a preshaped preform for use in molding processes as reinforcing material.

Claim 2

A method for preparing preforms which comprises (1) applying substantially evenly onto the surface of each of one or more plys of an unimpregnated substrate material one or more non-sintering thermoplastic-like resinous compounds which are substantially free of any compound which would serve as a crosslinker for said thermoplastic-like, solid resinous compound, said resinous compound being in the form of a powder having a particle size of less than about 500 microns and having a melting point of from about 50° C. to about 70° C. in an amount of from about 2 to about 12 percent by weight based upon the weight of said substrate material; (2) fusing said powdered thermoplastic-like resinous compound into a film on the surface of said substrate material: (3) cooling said resinous material: (4) assembling one or more plies of the thus treated substrate material and conforming said plies of said treated substrate material into a desired shape: (5) subjecting the thus shaped plies of treated substrate material at a temperature sufficient to melt said resinous compound; and (6) cooling said shaped treated plies of substrate material to a temperature below the melting point of said resinous compound; thereby forming a preshaped preform for use in molding processes as reinforcing material.

Claim 6

The method of any one of claims 1, 2, 3 or 4 wherein said non-sintering, solid, thermoplastic-like resinous compound is an epoxy resin, unsaturated polyester resin or vinyl ester resin, or any combination thereof; said substrate material is glass, graphite or carbon, or any combination thereof: and said substrate material is in the form of woven or non-woven fibrous material, random fibers, monofilaments, multi-strands of monofilaments or any combination thereof.