Preparation of polyamides from unstable diamines
CA 2037802 C · Owner: Irwin, Robert S. · Inventors: Irwin, Robert S.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
6-, A method is described for preparing high molecular weight polyamides comprising forming a slurry of the dihydrochloride of, (see formula), where X is C1 Br or lower alkyl (1-6 C atoms), and y is C1, Br, lower alkyl (1-6 C atoms) or hydrogen in a solvent for the diamine, reacting the dihydrochloride with a tertiary amine in an amount at least equivalent to the HC1 of the dihydrochloride to form free diamine in solution and treating the solution with an aromatic diacid chloride to form the polaymide.
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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
- Filed March 8, 1991 and granted January 22, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 8, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 8, 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.