Method and system for molding of thermoplastic optical polymers

Abstract

Provided herein are methods of molding thermoplastic polymers into optical elements. The optical elements in the form of cylindrical discs, semi-finished lens blanks or finished lenses are compression molded at high temperature typically above thermoplastic polymers softening temperature and under high pressure. The semi-finished lens blanks and finished lenses are molded using front and back glass molds inside a mold assembly which reshapes the cylindrical discs that are either previously molded or cut out from thick slab. Also provided are methods for producing single vision and progressive addition lens prescriptions.

What is claimed is: 
     
         1 . A method for making an optical element, the method comprising:
 providing sandwiched assembly comprising at least a front mold, a back mold, one or more annular rings, and at least a disc of thermoplastic material or a powder of thermoplastic material is held between front and back molds;   positioning the assembly between two platens of a hydraulic press;   heating the sandwiched assembly;   compressing the sandwiched assembly; and   cooling the sandwiched assembly and removing the formed thermoplastic optical element from the assembly.   
     
     
         2 . The method of  claim 1 , wherein the thermoplastic material comprises one or more polymers formed from petroleum or biobased monomers. 
     
     
         3 . The method of claim  0 , wherein the one or more polymers comprise one or more crosslinked polymers. 
     
     
         4 . The method of claim  0 , wherein the biobased monomers comprise sugar moieties derived from corn. 
     
     
         5 . The method of claim  0 , wherein the biobased monomers comprise sorbitol, isosorbide, isomannide, isoidide, and derivatives and combinations thereof. 
     
     
         6 . The method of claim  0 , wherein the one or more polymers comprise polyurethane, polycarbonate, polyester, polyamide, poly(meth)acrylate, or combinations thereof. 
     
     
         7 . The method of  claim 1 , wherein the powder of thermoplastic material has particle size<150 μm. 
     
     
         8 . The method of  claim 1 , wherein the disc of thermoplastic material having a diameter from 55 mm to 95 mm. 
     
     
         9 . The method of  claim 1 , wherein the disc of thermoplastic material having a center thickness from 1 mm to 25 mm. 
     
     
         10 . The method of  claim 1 , wherein the thermoplastic material is cut from a molded slab having predetermined dimensions. 
     
     
         11 . The method of  claim 1 , wherein the front glass mold and the back glass mold are each lined with a silicone pad positioned adjacent to the thermoplastic material upon insertion of at least a portion of the thermoplastic material into the assembly. 
     
     
         12 . The method of  claim 1 , wherein the one or more annular rings are interconnected and configured to hold nine sandwiched glass molds, and wherein the cooling forms nine thermoplastic optical elements. 
     
     
         13 . The method of  claim 1 , wherein the heating of sandwiched assembly is at a predetermined heating temperature and time. 
     
     
         14 . The method of claim  0 , wherein the predetermined heating temperature is between 100° C. and 210° C. 
     
     
         15 . The method of claim  0 , wherein the predetermined heating time is between 15 minutes and 30 minutes. 
     
     
         16 . The method of  claim 1 , wherein the compressing of sandwiched assembly is at a predetermined compression pressure and time. 
     
     
         17 . The method of claim  0 , wherein the predetermined compression pressure is between 100 psi and 20,000 psi. 
     
     
         18 . The method of claim  0 , wherein the predetermined compression time is between 30 seconds and 15 minutes. 
     
     
         19 . The method of  claim 1 , wherein the one or more thermoplastic optical elements are a semi-finished lens blank or a finished prescription lens. 
     
     
         20 . The method of  claim 1 , wherein the one or more thermoplastic optical elements are semi-finished lens blanks, finished single vision lenses, or finished progressive addition lenses.