Preparation of expandable styrene polymers
CA 2029208 A1 · Owner: Hahn, Klaus · Inventors: Hintz, Hans; Hahn, Klaus; Guhr, Uwe
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
_ 9 _ O.Z. 0050/41218, Abstract of the Disclosure: In the preparation of expandable styrene polymers by polymerizing styrene if, desired together with up to 50% by weight of other monomers, in aqueous suspension with addition of a C3- to C6-hydrocarbon as blowing agent and, if desired conven-, tional additives in effective amounts before during or, after the polymerization, foaming is reduced if the aqueous phase contains from 0.05 to 0.3% by weight of polyvinylpyrrolidone having a K value of from 100 to 150 as protective colloid.
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 November 2, 1990. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 2, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 2, 2012.
- 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.