Method of producing optically clear hydrophilic copolymers and contact lenses
CA 1106545 A · Owner: Wesley-Jessen, Inc. · Inventors: Shen, Chah M.; Loshaek, Samuel
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In the process of making optically clear hydrophilic copolymers formed by copolymerizing a glycol monoester of acrylic or methacrylic acid with an alkoxy monomer having the formula:, wherein R is a C1-C4 straight or branched chain alkoxy group R' is a C2 or C3 straight or branched chain alkylene group X, is hydrogen or a methyl group, m is either 1 or 0 and n is, an integer from 1 to 20, the improvement comprising distilling at least said alkoxy monomer under high vacuum and low temperature prior to copolymerization, promptly adding to said distilled monomer an amount of polymerization inhibitor below that which would inhibit copolymerization but sufficient to, provide a hydrated copolymer …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted August 4, 1981. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended August 4, 1998.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.