Process for producing poly (arylene sulfide)
CA 2197586 C · Owner: Kureha Kagaku Kogyo K.K. · Inventors: Sato, Hiroyuki; Miyahara, Michihisa; Satake, Yoshikatsu
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention provides a process for producing a poly(arylene sulfide) comprising a dehydration step of heating and dehydrating a mixture containing an organic amide solvent (a), an alkali metal sulfide and water to control a water content in the mixture and a subsequent polymerization step of subjecting the alkali metal sulfide and a dihalo-aromatic compound to a polymerization reaction in the organic amide solvent (a) wherein, hydrogen sulfide vaporized off during the dehydration step is absorbed in another organic amide solvent (b) outside a system in which the dehydration step is carried out thereby recovering it, and the hydrogen sulfide thus recovered is reused in the polymerization …
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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 February 14, 1997 and granted January 2, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 14, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 14, 2019.
- 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.