Patent ID: 8455637

Claim:
Cellulose acetate having a degree of acetyl substitution in the range of 2.636 to 2.958, wherein the cellulose acetate shows a distribution curve of an intermolecular substitution degree in which the maximum peak has a half width of less than Y defined in the following formula: Y=− 0.17788 X+ 0.5788 in which X is the degree of acetyl substitution, and wherein the degrees of acetyl substitution at 2-, 3- and 6-positions satisfy the following formulas (I), (II), (III), and (VI): 2DS+3DS<6DS×4−1.70 (I) 2DS+3DS<−6DS×4+5.70 (II) 2DS+3DS>1.80 (III) 2DS+3DS−6DS<1 (VI) in which 2DS is the degree of acetyl substitution at 2-position; 3DS is the degree of acetyl substitution at 3-position; and 6DS is the degree of acetyl substitution at 6-position.