Preparation method of cellulose acetate

The invention belongs to the field of high polymer chemistry, and relates to a preparation method of cellulose acetate. The product obtained by the method provided by the invention has the advantages of high degree of substitution and high viscosity. The method comprises the following steps: A. soaking 1 part by weight of cellulose with 8-20 parts by weight of glacial acetic acid at 20-60 DEG C; B. esterifying at 20-58 DEG C for 3-8 hours by adding 4-6 parts by weight of acetic anhydride and 0.005-0.05 part by weight of catalyst; C. adding 0.5-1.5 parts by weight of 60-80% acetic acid at 15-25 DEG C, and reacting until the content of acetic acid in the cellulose acetate reaches 60.5-62.5%; D. adding 1.1-1.5 parts by weight of 5-15% acetate water solution, and reacting at 20-50 DEG C for 1-3 hours; and E. filtering, settling and granulating. The product obtained according to the invention has the advantages of high degree of substitution (the content of acetic acid in the product is higher than or equal to 60.