To easily obtain a molded article having a superior mechanical strength and a high degree of polymerization by acetylating solid cellulose directly with acetyl chloride by means of a dissolution method in a solvent without subjecting the cellulose to pretreatment.
There are no specific limitation for a cellulose to be used, which includes a bacterial cellulose (hereinafter BC) as well as a vegetable cellulose. An acetylated material with a high degree of polymerization is obtained from a BC. A BC that is obtained by means of an aerated stirring culture and has a weight-average degree of polymerization (in terms of polystyrene) of not less than 1.6×104 or a BC that is obtained by means of a stationary culture and has a weight-average degree of polymerization of not less than 2.0×104 is used. There is no special limitation for the conditions of acetylation, as long as solid cellulose is acetylated with acetyl chloride and becomes soluble. Acetyl chloride can act as a solvent as well. For example, keeping the mixture of 1 pt.wt. cellulose and 3-40 pts.wt. excessive acetyl chloride for 4-24hr at 20-30°C will achieve the purpose.
WATABE OTOHIKO
MORINAGA YASUSHI
HORII FUMITAKA
