Polyimides and process for the preparation thereof
CA 2001496 C · Owner: Mitsui Toatsu Chemicals, Inc. · Inventors: Ohta, Masahiro; Kawashima, Saburo; Yamaguchi, Akihiro
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention relates to polyimides having excellent thermal resistance and process for preparing the same comprising carring out condensation of 4,4'- bis(3-aminophenoxy)biphenyl with pyromellitic dianhydride in the presence of a diamine compound and/or tetracarboxylic acid dianhydride. The polyimides have a non-crystalline structure and exhibit excellent thermal resistance and processability.
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 October 25, 1989 and granted October 21, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended October 25, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 25, 2011.
- 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.