Process for the production of foamed polymer particles
CA 2055358 A1 · Owner: Tsurugai, Kazuo · Inventors: Tsurugai, Kazuo; Kuwabara, Hideki; Oikawa, Masaharu
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
of Disclosure, Disclosed herein is a production process of foamed polymer particles, wherein particles of a polymer which, contain a silica-alumina adsorbent in which the molar ratio of SiO2/A1203 is at least 1.15, are dispersed in a dispersion medium in the presence of carbon dioxide in a closed vessel, the resultant dispersion is heated to a temperature not lower than the softening temperature of the polymer to impregnate the polymer particles with carbon dioxide, and the polymer particles and the dispersion medium are then released into an atmosphere of a pressure lower than the internal pressure of the vessel thereby expanding the polymer particles. The polymer may be an uncrosslinked …
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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 November 13, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 13, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 13, 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.
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.