| 摘要 |
A process for preparation of alkylhydroxyalkyl cellulose, e.g. methylhydroxyethyl cellulose and methylhydroxypropyl cellulose is new. <??>Alkylhydroxyalkyl cellulose is prepared by: <??>(a) alkalization of cellulose with alkali hydroxide l /AGU (sic) (0.9 - 2.9 equivalents) as aqueous lye, in the presence of a suspension agent containing alkyl halide ( ≥ 0.2 equivalents/AGU); <??>(b) reaction of the alkalized cellulose with alkylation and hydroxyalkylation agents at 65 degrees C; <??>(c) addition of further alkali hydroxide as aqueous lye; <??>(d) metering in of alkylation agent in amount at least equal to the difference between the already used equivalents of alkylation agent l/AGU and the total amount of metered in equivalent of alkali hydroxide/AGU, with no metering in when the amount of equivalent alkylation agent l/AGU already exceeds the total amount of alkali hydroxide/AGU metered in; and <??>(e) isolation of the alkylhydroxycellulose obtained from the reaction mixture and purification if required. |
