| 摘要 |
PROBLEM TO BE SOLVED: To obtain a highly concentrated cellulose acylate dope freed from agglomerates of a powder and reduced in filtration load by mixing a cellulose acylate with a poor solvent therefor, mixing the obtained mixture with a solvent based on a good solvent for the cellulose acylate without separating the poor solvent from the mixture to dissolve the acylate. SOLUTION: This dope is prepared by mixing a cellulose acylate with a poor solvent such as methanol and dissolving the obtained mixture in a good solvent such as trimethylene chloride under agitation under a pressure of 3-4,000 kgf/cm2 and a shearing force of 1×101 to 1×105 kgf/m/sec2 in a mixing ratio of the cellulose acylate to the entire solvent amount of 16-40 wt.%. The cellulose acylate used is the one satisfying the relationships: 2.6<=A+B<=3.0; 2.0<=A<=3.0; 0<=B<=0.8; and 1.9<A-B and is exemplified by cellulose triacetate, or cellulose acetate butyrate. In the formulas, A and B are each the degree of substitution of cellulosic hydroxyl groups with acetyl groups or with 3-5C acyl groups.
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