Process for the production of polyisocyanates of the diphenylmethane series by phosgenation of non-neutralised polyamine of the diphenylmethane series
CA 2442464 A1 · Owner: Hagen, Torsten · Inventors: Hagen, Torsten; Wershofen, Stefan; Pirkl, Hans-Georg
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention relates to a method of producing polyisocyanates of the diphenylmethane series including the steps of a) reacting aniline and formaldehyde in the presence of HCl to provide a product mixture containing polyamines of the diphenylmethane series, HCl, aniline and water; b) removing excess aniline and water by distillation to provide a product mixture comprising polyamines of the diphenylmethane series, HCl, no more than 10 wt.% aniline based on the polyamines, and no more than 5 wt.% water based on the polyamines; and, c) phosgenating the product mixture in (b).
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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 September 25, 2003. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended September 25, 2023.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 25, 2025.
- 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
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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.