Process for preparation of alkali cellulose ester sulfates
AssigneeJohnson & Johnson
InventorDeger C. Tunc
Life of this patent
Estimating the term…
Abstract
A barrier film is provided for a product used in contact with body fluids. The barrier film comprises an alkali salt of a sulfated cellulose ester, with a degree of sulfate substitution satisfactory to render the film resistant to body fluids and yet dispersible in low salt concentration aqueous solutions such as those found in a household water closet. There is also disclosed a process for preparing alkali salts of sulfated cellulose esters comprising sulfating woodpulp, acylating the sulfated wood pulp, and precipitating the desired product in an aqueous precipitation medium maintained at a specified pH range.
Claims7
A process for the preparation of alkali cellulose ester sulfates having a degree of sulfate substitution of from about 0.1 to about 0.45 and a degree of acyl substitution of from 1.63 to 2.69 which comprises:
- a. slurrying the cellulose in an inert organic liquid;
- b. sulfating the cellulose by reacting the cellulosic slurry with a sulfating mixture comprising an alkali acetyl sulfate;
- c. esterifying the sulfated cellulose in a reaction mixture comprising said inert organic liquid, said sulfated cellulose, and an acylating agent;
- and
- d. precipitating said alkali cellulose ester sulfate by combining said reaction mixture with an aqueous precipitation medium maintained at a pH of from about 3 to about 8.
In a process for recovering a cellulose ester sulfate having a degree of sulfate substitution of from about 0.1 to about 0.45 and a degree of acyl substitution of from 1.63 to 2.69 from a solution comprising an inert organic liquid and said cellulose ester sulfate, the step which comprises combining said solution with an aqueous precipitation medium maintained at a pH of from about 3 to about 8.
Dependencies are inferred from the claim text.