Expired Canadian patentCanada
Free radical polymerization of vinyl aromatic monomers
CA 2101334 C · Owner: The Dow Chemical Company · Inventors: Priddy, Duane B.; Shero, Eric J.; Dais, Virginia A.
Overview
Drawings and full text
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
High. molecular weight polystyrene is prepared by free radical polymerization of styrene monomer in the presence of 5 to 5000 ppm of a soluble organic acid having pKa from 0.5 to 2.5.
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 17, 1991 and granted August 5, 2003. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 17, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 17, 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.
FiledDecember 17, 1991
GrantedAugust 5, 2003
Term endedDecember 17, 2011
Patent numberCA 2101334 C
Classification (IPC)C08F112/08
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.