Method and system for molding of thermoplastic optical polymers
AssigneeNovol, Inc.
InventorsJagdish Jethmalani, Sanjiban Chakraborty, Monica Bhatia
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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.
Claims23
A method for making an optical element, the method comprising:
- providing a thermoplastic material, wherein the thermoplastic material has the shape of a disc or slab or is in the form of a polymer powder;
- providing an assembly comprising one or more annular rings configured to hold one or more sandwiched glass molds, wherein each sandwiched glass mold comprises a front glass mold and a back glass mold, wherein a front glass back surface of the front glass mold has a front mold radius, and wherein a back glass front surface of the back glass mold has a back mold radius;
- inserting at least a portion of the thermoplastic material between the front glass mold and the back glass mold of the assembly;
- positioning the assembly between two platens of a hydraulic press;
- heating the assembly to a predetermined heating temperature for a predetermined heating time;
- compressing the assembly at a predetermined compression pressure for a predetermined compression time;
- cooling the assembly, thereby forming one or more thermoplastic optical elements, wherein each thermoplastic optical element comprises an optical element front surface and an opposite optical element back surface, wherein the optical element front surface has a front surface radius substantially equal to the front mold radius, and wherein the optical element back surface has a back surface radius substantially equal to the back mold radius;
- and
- removing the one or more thermoplastic optical elements from the assembly.
Dependencies are inferred from the claim text.