Essilor International

Shawn McDermott

Hao-Wen Chiu

Shannon Loiselle

David Bracero

A method for injection molding of a weld line free minus power lens element comprises injecting a melt of thermoplastic material at a temperature higher than a glass transition temperature (Tg) of the thermoplastic material in an initial molding cavity delimited by two facing mold inserts, wherein the melt of thermoplastic material comprises at least one UV absorber. During the injecting, the two facing mold inserts are moved toward one another to define a final molding cavity whose volume is less than that of the initial molding cavity. After cooling and disassembling of the two facing mold inserts, the weld line free minus power lens element is recovered. One of the two facing mold inserts comprises a flat surface facing the initial molding cavity, thereby to form a flat surface on one side of the weld line free minus power lens element. The other of the two facing mold inserts comprises a convex surface facing the initial molding cavity, thereby to form a concave surface on an opposite side of the weld line free minus power lens element.

Method for injection molding weld line free minus power lens elements

A method for injection molding of a plus power lens element comprises injecting a melt of thermoplastic material comprising at least one UV absorber at a temperature higher than a glass transition temperature (Tg) of the thermoplastic material in an initial molding cavity delimited by two facing mold inserts. During the injecting, the two facing mold inserts are moved toward one another to define a final molding cavity whose volume is less than that of the initial molding cavity. After cooling and opening of the mold cavity, the plus power lens element is recovered. One of the two facing mold inserts comprises a flat surface facing the initial molding cavity, thereby to form a flat surface on one side of the plus power lens element, and the other of the two facing mold inserts comprises a concave surface facing the initial molding cavity, thereby to form a convex surface on an opposite side of the plus power lens element.

Growing community of inventors

Dallas, TX, United States of America

Shawn McDermott