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US 4,537,958 AGranted
Process for preparing cellulose ethers
AssigneeThe Dow Chemical Company
InventorsCarl P. Strange, Harold B. Martin, Jr., Albert C. Tsang
Life of this patent
Estimating the term…
Abstract
Non-gelling cellulose ethers are purified by mixing same with a dialdehyde under acidic conditions and under high agitation, forming a slurry of the treated cellulose ether, rapidly transferring the slurry to a filter and then dewatering said slurry.
Claims8
A process for purifying a crude non-gelling water-soluble cellulose ether comprising (a) mixing under high agitation, a crude non-gelling water-soluble cellulose ether prepared in a dry process, or in a slurry in a liquid organic diluent, wherein substantially all of the diluent has been removed;
- with from about 1 to about 5 percent by weight of said cellulose ether of a dialdehyde under acidic conditions, whereby the cellulose ether is rendered substantially water-insoluble, (b) forming an aqueous slurry of the crosslinked cellulose ether, (c) transferring said slurry to a filter by means of a slurry pump such that substantially none of the cellulose ether becomes dissolved in the water and (d) dewatering said slurry on a filter to remove water-soluble impurities therefrom.
Dependencies are inferred from the claim text.