| 摘要 |
PROBLEM TO BE SOLVED: To obtain a molded article having a high degree of polymerization and resultantly a superior mechanical strength by using a bacterial cellulose as a cellulose material in an acetylation reaction wherein the cellulose is first dipped in acetic acid and then an acetylating agent consisting of acetic anhydride, methylene chloride and a small amount of sulfuric acid is made to act on the mixture. SOLUTION: A cellulose with a high degree of polymerization is produced by a cellulose-producing bacterium (stipulation no.: FERM P-14982). For example, an aerated stirred culture yields a cellulose with a weight-average polymerization degree (in terms of polystyrene) of not less than 1.6×10<4> and a stationary culture yields a cellulose with a weight-average polymerization degree of not less than 2.0×10<4> . In the acetic acid dipping process, 1 pt.wt. cellulose is dipped in 3-20 pts.wt. acetic acid and separated from acetic acid by means of a centrifuge and the like. 30-200 pts.wt. acetic anhydride, 40-200 pts.wt. methylene chloride and 0.1-10 pts.wt. conc. sulfuric acid are added to 10 pts.wt. cellulose and the mixture is kept at 20-50 deg.C for 0.5-7hrs and subsequently cast in a large amount of water.
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