To enable the production of cellulose acetate solution useful for photographic materials, etc., by adopting the highest possible cooling temperature in a cooling dissolution method.
A mixture of (A) a cellulose acetate having 58.25-62.5% average acetyl content with (B) an organic solvent is cooled to a temperature (T) defined by formula I [when the average acetyl content (Dac) of the component A is 58.25-60.0%] or formula II (when the Dac is 60.0-62.5%) in a cooling step when dissolving the component A in the component B and providing the objective solution according to the step for cooling the mixture of the components A and B to ≤0°C and a step for heating the cooled mixture to 5-50°C. Furthermore, the component A preferably has 250-400 viscosity-average polymerization degree and the content of a low-molecular component is preferably low so as to afford ≤10wt.% fraction of an acetone extract.
SHIMAMOTO SHU
TAKEMOTO HIROYUKI
HANIYU NAOTO
