Method for the preparation of a polyvinyl chloride resin
CA 2067018 A1 · Owner: Shin-Etsu Chemical Co. Ltd. · Inventors: Amano, Tadashi; Kaneko, Ichiro
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method for the suspension polymerization of vinyl chloride is proposed to provide an improvement in the properties of the polyvinyl chloride resin product obtained thereby such as an increased bulk density of the resin powder and a decreased content of fish eyes therein. The improvement can be obtained by the unique combination of three kinds of water-soluble dispersing agents and unique timing of addition thereof to the aqueous polymerization medium including (A) a first partially saponified polyvinyl alcohol of 65 to 75% of the degree of saponification and 750 to 850 of the average degree of polymerization and (B) a hydroxypropyl methyl cellulose of specified degrees of substitution …
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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 April 23, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended April 23, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 23, 2014.
- 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.