The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 03, 1995
Filed:
Sep. 02, 1993
Applicant:
Inventors:
Assignee:
Dextran Products Limited, Scarborough, CA;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C08B / ; C08B / ; C07H / ;
U.S. Cl.
CPC ...
536 59 ; 536 70 ; 536 75 ; 536 83 ; 536118 ; 536122 ;
Abstract
The present invention provides a process for the preparation of water soluble alkali metal salts of cellulose sulfate having a degree of substitution ranging from 1 to 3 and viscosity of 1 percent aqueous solution in excess of 20 centipoises (cps). The process involves the use of chlorosulfuric acid as a sulfonating agent in the presence of pyridine used as a solvent in reaction. The important steps of the process for preparation of the water soluble salts include presoaking of the cellulose in pyridine followed by washing the pyridine salt with an alcohol such as methanol and reacting saturated alkali metal bicarbonate or carbonate solutions with the sulfonated cellulose.