Optical material
CA 2049439 C · Owner: Ishikawa, Tomohiro · Inventors: Ishikawa, Tomohiro; Doi, Toru
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An optical material, comprising a resin composed of a polymer constituted of 10 of 95 mol % based on the, polymer, of a first structural unit represented by the formula (I) and 90 to 5 mol %, based on the polymer of a, second structural unit represented by the formula (II) and having a weight-average molecular weight of from 1 x 3 to 5 x 10 6 in polystyrene equivalent: (see formula 1), The optical material has a Tg value not less than 120°C a, light transmittance value not less than 85 % and a pencil, hardness not lower than H.
Read the whole patent
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
- Filed August 19, 1991 and granted November 26, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 19, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 19, 2013.
- 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.