Importance

Loading Importance Indicators...

Abstract

A process for forming a preform for use in compression molding an optical lens is provided. A heated reservoir desirably a thermoplastic extruder is filled with a thermoplastic material. The heated reservoir has a fluid outlet which is located in close proximity to the concave mold. The thermoplastic material, for example, polycarbonate pellets is fluidized in the heated reservoir. A predetermined amount of a fluid thermoplastic material is dispensed from the reservoir outlet onto the outside the edge of a heated concave mold prior to the fluid solidifying so that the fluid makes point or line contact as it first contacts the concave molds. The fluid flows down the sloping wall of the concave mold into the concave mold and forms a blob of material having a greater thickness at the center of the concave mold than at the periphery of the mold. The thermoplastic blob is then allowed to cool below its melting temperature. A monolithic preform mass is formed having a skin and having a flat to slightly convex surface which will make point or line contact with the top convex mold.

Loading the Abstract Image...

First Claim