Patent ID: 7893138

Claim:
A carboxy(C 1 -C 3 )alkylcellulose ester having the following properties: a maximum degree of substitution per anhydroglucose unit of from 3.08 to 3.50, comprised of the following substitutions: a degree of substitution per anhydroglucose unit of carboxy(C 1 -C 3 )alkyl of from 0.20 to 1.2, a degree of substitution per anhydroglucose unit of hydroxyl of from 0.10 to 0.90, a degree of substitution per anhydroglucose unit of butyryl of from 1.10 to 2.55, and a degree of substitution per anhydroglucose unit of acetyl of from 0.10 to 0.90; an inherent viscosity of 0.05 to 0.13 dL/g, as measured in a 60/40 (wt./wt.) solution of phenol/tetrachloroethane at 25 ° C.; a number average molecular weight (M n ) of from about 1,000 to about 7,000; a weight average molecular weight of from about 1,500 to about 23,000; and a polydispersity of from about 1.20 to about 7.0.