Process for continuous purification of bisphenols
CA 2005470 C · Owner: Van Shaw, Paul · Inventors: Buechele, James L.; Van Shaw, Paul; Dong, Walter
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 process for the continuous purification of crude bisphenol which comprises (1) forming a single liquid phase comprising a hot mixture of crude bisphenol and water in a ratio substantially of from 75% to 85% weight of crude bisphenol to 15% to 25% weight water; (2) continuously feeding this mixture together with a stream of warm water to a first crystallization zone at a temperature sufficient to maintain a bisphenol-rich liquid phase, a water-rich phase and a crystalline phase comprising 70% to 95% of the total bisphenol in the mixture; (3) passing the three-phase mixture of bisphenol and water to a second crystallization zone operated at 85 °C to 97 °C until 90% …
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 December 14, 1989 and granted April 27, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 14, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 14, 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.