EP0210917A2
Expired / Lapsed
EP
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A method for the preparation of a cellulose ether having a decreased degree of polymerization
Assignee: Shin-Etsu Chemical Co Ltd
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Filing: 1986-07-21
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Granted: —
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Expires: 2006-07-21
Abstract
Abstract The invention provides a method for preparing a water-soluble cellulose ether of high whiteness having a decreased average degree of polymerization suitable as a film-coating agent of solid medicament forms free from the problem of noxious impurities. The method comprises contacting the starting cellulose ether with an aqueous solution of hydrogen chloride in an amount limited in respect to the amounts of hydrogen chloride and water at 40 to 85 °C for a length of time to effect molecular weight decrease followed by dissipation of hydrogen chloride and water.
Inventors
- 👤 Tohru Chiba
- 👤 Hiroaki Muto
- 👤 Kazumasa Maruyama
- 👤 Atsushi Hatayama
- 👤 Yuichi Nishiyama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 01:49
CPC Classifications
C; C08; C08B; C08B11/00; C08B11/20; A; A61; A61K; A61K9/00; A61K9/20; A61K9/28; A61K9/2806; A61K9/2833; A61K9/286; A61K9/2866
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
129 words
A method for the preparation of a water-soluble cellulose ether having a decreased average degree of polymerization which comprises: (a) contacting a starting cellulose ether in a powdery form with an aqueous solution of hydrogen chloride in such an amount that the amount of the hydrogen chloride is in the range from 0.1 to 1.0 % by weight based on the starting cellulose ether and the amount of water is in the range from 3 to 8 % by weight based on the overall amount of the starting cellulose ether and the aqueous solution of hydrogen chloride at a temperature in the range from 40 to 85 °C; and (b) removing the hydrogen chloride from the mixture of the powdery cellulose ether and the aqueous solution of hydrogen chloride.
Claim 2
Independent Claim
129 words
A method for the preparation of a water-soluble cellulose ether having a decreased average degree of polymerization which comprises: (a) contacting a starting cellulose ether in a powdery form with an aqueous solution of hydrogen chloride in such an amount that the amount of the hydrogen chloride is in the range from 0.1 to 1.0 % by weight based on the starting cellulose ether and the amount of water is in the range from 3 to 8 % by weight based on the overall amount of the starting cellulose ether and the aqueous solution of hydrogen chloride at a temperature in the range from 40 to 85 °C; and (b) removing the hydrogen chloride from the mixture of the powdery cellulose ether and the aqueous solution of hydrogen chloride.
Claim 3
Dependent Claim
40 words
The method as claimed in claim 1 wherein the amount of water is in the range from 5 to 8 % by weight based on the overall amount of the starting cellulose ether and the aqueous solution of hydrogen chloride.
Claim 4
Dependent Claim
34 words
The method as claimed in claim 1 wherein the temperature at which the starting cellulose ether is contacted with the aqueous solution of hydrogen chloride is in the range from 60 to 80 αC.
References Cited (Backward Citations)
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