초록 ▼

Fiber reinforced thermoplastic parts having good surface characteristics are produced by a process involving: preheating fiber reinforced composite to achieve at least a flowable viscosity of the polymer, and (2) molding under controlled rheological conditions. The preheating is conducted on composi

Fiber reinforced thermoplastic parts having good surface characteristics are produced by a process involving: preheating fiber reinforced composite to achieve at least a flowable viscosity of the polymer, and (2) molding under controlled rheological conditions. The preheating is conducted on composites that are predominantly amorphous thermoplastic polymers, copolymers, polyblends or alloys reinforced with continuous glass fiber strand reinforcing mat. The amount of the mat present in the laminate is less than around 40 weight percent of the composite. The temperature of preheating is at least greater than the glass transition temperature of the polymer and less than the degradation temperature of the polymer to expand the composite. The preheated composites are compression molded in an effective charge and at a pressure of at least around 500 to 6,000 psi, where at least one die surface of the mold is maintained at a temperature in the range of the glass transition temperature of the polymer to a temperature of 70°F. (39°C.) below the glass transition temperature of the polymer.

대표청구항 ▼

Process of molding fiber reinforced thermoplastic parts having at least one smooth surface, comprising: preheating at least one laminate of predominantly amorphous thermoplastic polymer, copolymer, terpolymer, blend or alloy that is reinforced with glass fiber strand reinforcing mat selected from th

Process of molding fiber reinforced thermoplastic parts having at least one smooth surface, comprising: preheating at least one laminate of predominantly amorphous thermoplastic polymer, copolymer, terpolymer, blend or alloy that is reinforced with glass fiber strand reinforcing mat selected from the group consisting of needled, continuous glass fiber strand mat, chemically bonded glass fiber strand mat, and continuous glass fiber strand mat where the mat is present in an amount in the range of less than 40 weight percent of the laminate where preheating is at an effective temperature that is in the range of less than the degradation temperature of the polymer to a temperature to at least soften the amorphous polymer and to melt any semicrystalline polymer whereby the polymer has a viscosity less than 20,000 poise and whereby the laminate expands; and molding an effective charge of the heated laminate by compression molding at a pressure in the range of about 500 to about 6,000 psi and with at least one mold surface at a temperature in the range of from the Tg temperature to 70°F. (39°C.) below the Tg temperature of the polymer to reduce the shear modulus at the surface of the laminate contacting said mold surface to produce the molded, reinforced, predominantly amorphous thermoplastic part.