Method for the production of substituted polysaccharides via reactive extrusion

摘要

A reactive extrusion process for the production of substituted polysaccharides, in particular, cellulose acetate, starch acetate, carboxymethyl cellulose, and carboxymethyl starch.

主权项

1. A process for the acetylation of a polysaccharide via reactive extrusion to form a polysaccharide acetate, the process comprising:
(a) forming an extrusion mixture comprising the polysaccharide, acetic anhydride, and iodine, wherein the polysaccharide is selected from the group consisting of a starch and a cellulose, and wherein the extrusion mixture has a weight ratio of acetic anhydride to polysaccharide is in the range from about 0.5 to about 5, and wherein the amount of iodine is in the range from about 0.04 to about 3% by weight of the acetic anhydride; (b) feeding the extrusion mixture into an extruder, wherein the extruder has a number of kneading blocks in the range from 1 to 7 and a number of compression screws in the range from 5 to 12; and (c) extruding the extrusion mixture to acetylate the polysaccharide and form an extrudate comprising the polysaccharide acetate, wherein the extruding step has a duration in the range from about 2 to about 7 minutes and further comprises maintaining the extruder at a temperature in the range from about 100 to about 190° C., and wherein the polysaccharide acetate has a degree of substitution (DS) in the range from about 0.1 to 1, and wherein the acetylation reaction has a reaction efficiency (RE) that is in the range of about 5% to about 80%.