| 摘要 |
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 mum, and mixing the filtered solution with a poor solvent to reprecipitate cellulose acylate: <?in-line-formulae description="In-line Formulae" end="lead"?>1.5<=A+B<=3Formula 1<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>0<=A<=1.8 Formula 2<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>1.2<=B<=3 Formula 3<?in-line-formulae description="In-line Formulae" end="tail"?> 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, <?in-line-formulae description="In-line Formulae" end="lead"?>M/S={(a molar content of alkali metal)/2+(a molar content of alkali earth metal)/2}/(a molar content of sulfur). Formula 4<?in-line-formulae description="In-line Formulae" end="tail"?>
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