| 摘要 |
A 6-position highly acetylated cellulose diacetate is provided to be useful as materials of cellulose-mixed acylate with total substitution degree of acetyl group having high optical characteristic. A 6-position highly acetylated cellulose diacetate having a total degree of acetyl substitution of 2.0 or more and less than 2.6, has a 6-percent viscosity of 40 to 600 mPa.s and a total degree of acetyl substitution of DSt and a degree of acetyl substitution at the 6-position of DS6, wherein DSt and DS6 satisfy following conditions (1): 2.0=DS6/DSt>=0.531-0.088xDSt.
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