Process of preparing polyimides
CA 2020738 A1 · Owner: Simharl, Reinhold · Inventors: Seidl, Sigrid; Simharl, Reinhold; Weinrotter, Klaus
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In preparing polyimides by heating a solution of intramolecular tetracarboxylic acid dianhydrides and organic diisocyanates in an aprotic organic solvent in the presence of a polymerization accelerator a, catalytic amount of an alkali metal hydroxide is used as the polymerization accelerator. By this process polyimides having high molecular weights are produced in a simple manner. The polyimides produced exhibit a hightemperature resistance.
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 July 9, 1990. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended July 9, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 9, 2012.
- 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.