Method of cast molding contact lenses

• US 5,843,346 A
• Filed: 08/01/1996
• Issued: 12/01/1998
• Est. Priority Date: 06/30/1994
• Status: Expired due to Term

• Current Assignee: Bausch & Lomb Incorporated (Bausch Health Cos., Inc.)
• Original Assignee: Polymer Technology Group, Inc. (DSM-Firmenich AG)
• Inventors: Morrill, Timothy J.
• Primary Examiner(s): Vargot, Mathieu D.
• Application Number:
  US08/695,197
• Time in Patent Office: 852 Days
• Field of Search: 264/2.5, 264/219, 425/808
• US Class Current: 264/2.5
• CPC Class Codes: B29D 11/00076 enabling passage of fluids, e.g. oxygen, tears, between the area under the lens and the lens exterior
• CPC Class Codes: B29D 11/00125 Auxiliary operations, e.g. removing oxygen from the mould, conveying moulds from a storage to the production line in an inert atmosphere
• CPC Class Codes: B29K 2023/00 Use of polyalkenes or derivatives thereof as moulding material
• CPC Class Codes: Y10S 425/808 Lens mold

Abstract

An improved method for cast molding RGP contact lenses employs mold sections injection molded from a specific class of thermoplastic, polyolefin resins.

Claims

1. In a method of cast molding a contact lens that comprises curing a lens-forming mixture in a lens-shaped cavity formed between molding surfaces of first and second mold sections of a mold assembly,

the improvement wherein at least one of said mold sections is injection molded from a thermoplastic polyolefin resin having a melt flow rate of at least about 21 g/10 min.

2. The method of claim 1, wherein both the first and second mold sections are injection molded from a thermoplastic polyolefin resin having a melt flow rate of at least about 21 g/10 min.

3. The method of claim 2, wherein the resin is a thermoplastic polypropylene resin having a melt flow rate of at least about 21 g/10 min.

4. The method of claim 1, wherein the resin is a thermoplastic polypropylene resin having a melt flow rate of at least about 21 g/10 min.

5. The method of claim 1, wherein the contact lens is formed of a rigid, gas permeable material.