Preparation process of cellulose acetate

The invention belongs to the field of polymer chemistry, and relates to a preparation process of cellulose acetate. The process is easy to operate, and the product has high substitution degree and high viscosity. The preparation process comprises the following steps of: A, activating 1 weight part of cellulose by using 8 to 20 weight parts of glacial acetic acid at the temperature of between 20 and 60 DEG C; B, adding 4 to 6 weight parts of acetic anhydride and 0.005 to 0.05 weight part of catalyst, and performing esterification at the temperature of between 20 and 58 DEG C for 3 to 8 hours; C, adding 0.5 to 1.5 weight parts of high-concentration aqueous solution of acetic acid at the temperature of between 10 and 25 DEG C, and reacting till the content of the acetic acid is 60.5 to 62.5 percent, wherein the high-concentration aqueous solution of acetic acid is 80 percent aqueous solution of acetic acid; D, adding 0.3 to 1 weight part of 5 to 15 percent aqueous solution of acetate, and reacting for 15 to 45 m