Method for the preparation of a vinyl chloride-based polymer
CA 2054865 A1 · Owner: Fujimoto, Tatsuya · Inventors: Kaneko, Ichiro; Fujimoto, Tatsuya
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An improvement is proposed for the method of suspension polymerization of vinyl chloride monomer or a monomer mixture mainly composed thereof to produce a polyvinyl chloride resin powder having excellent absorptivity of plasticizers and containing a greatly decreased amount of fish eyes. The improvement consists in the use of a specific suspending agent which is a combination of (a) a modified, partially saponified polyvinyl alcohol of, which the modifying monomeric unit is an ethylene unit having a pyrrolidone group, caprolatam group, oxazolidinone group or 5methyloxazolidinone group as the modifying group and (b) a hydroxypropyl methyl cellulose of specified degrees of substitution of the …
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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 4, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 4, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 4, 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
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.