Method of purifying bisphenols
CA 2005469 C · Owner: Shell Canada Limited · Inventors: Nielsen, Edward L.; Van Shaw, Paul; Buechele, James L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for the preparation of crystals of an adduct of a bisphenol with a phenol which comprises: (a) adding an inert volatile liquid aliphatic hydrocarbon diluent and 0-1.5% weight water to a crude mixture of the bisphenol and the phenol at a temperature above the boiling temperature of the added volatile liquid diluent; and, (b) allowing the volatile liquid diluent to boil in the process thereby cooling the resulting mixture of bisphenol and phenol to a temperature at which adduct crystals form.
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.