Patent ID: 7521127

Claim:
A method for producing a cellulose acylate composition, which comprises filtering a solution in which cellulose acylate satisfying the following formulae 1 to 3 and having an M/S defined by following formula 4 of 0.5 to 2 is dissolved in a solvent through a filter having a retention particle size of 0.1 to 40 μm, and mixing the filtered solution with a poor solvent to reprecipitate cellulose acylate: 1.5 ≦A+B ≦3 Formula 1 0≦A≦1.8 Formula 2 1.2≦B≦3 Formula 3 where A is a substitution degree for an acetyl group of a hydrogen atom which constitutes a hydroxyl group of cellulose, and B is a substitution degree for an acyl group having 3 to 7 carbon atoms of a hydrogen atom which constitutes a hydroxyl group of cellulose, M/S ={(a molar content of alkali metal)/2+(a molar content of alkali earth metal)/2}/(a molar content of sulfur). Formula 4