| 摘要 |
1,139,150. Cellulose esters. SOC. RHODIACETA. 16 Dec., 1966 [28 Dec., 1965], No. 56444/66. Heading C3A. Cellulose esters, e.g. triacetate, are produced continuously by first treating the cellulose with all of the required esterification catalyst and with a diluent such that the mixture contains 3-5 parts of diluent per part of cellulose, then adding to the mixture after 5-10 min., 2-3 parts of one or more C 1-4 monocarboxylic acid anhydrides, together with 0-1À5 parts of the diluent, and finally, after 6-10 min. from the anhydride addition, dilating the mixture with 1-4 parts of the diluent. (All parts are by weight.) Specified is acetic anhydride, using acetic acid as diluent; methylene chloride or one or more C 2-4 monocarboxylic acids may partly or wholly replace the acetic acid. The use of 5-7% of a 4: 6 mixture of sulphuric and perchloric acids as catalyst is specified. The process may be conducted in apparatus accordmg to Specification 802,863. |
