Method for the preparation of an acidic dicarboxylic acid ester of cellulose ether
CA 1300611 C · Owner: Maruyama, Kazumasa · Inventors: Sekigawa, Fujio; Muto, Hiroaki; Chiba, Tohru
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A hydroxypropoxyl-containing cellulose ether e.g. hydroxypropyl, cellulose and hydroxypropyl methyl cellulose is esterified into an acidic, dicarboxylic acid ester useful as a enteric coating material of solid medicament forms. The esterification reaction of 100 parts by weight of the cellulose ether with phthalic or succinic anhydride optionally combined with acetic anhydride is performed in 200 to 700 parts by weight of acetic acid as a solventin the presence of 50 to 150 parts by weight of an alkali metal acetate e.g. sodium acetate. The cellulose ether product is so tough and resistant against attack of a simulated gastric juice that the solid medicament forms coated therewith are …
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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
- Granted May 12, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended May 12, 2009.
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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.