| 摘要 |
<p>Cellulose is hydroxyalkylated to an MS not exceeding 1.0 in the presence of an alkali and water and a substantially water-miscible ketone as diluent, the alkali/cellulose and water/cellulose ratios being 0.2/1-0.8/1 and 0.8/1-4.0/1 respectively, and after neutralization of 70%-98% of the alkali, is subjected to further hydroxyalkylation to MS 1.5-3.0. With the remaining amount of alkali without isolating the partially hydroxyalkylated product. The process is applicable to the formation of e.g. hydroxyethyl, hydroxypropyl and hydroxybutyl celluloses using such hydroxyalkylating agents as e.g. ethylene oxide, propylene oxide, mesityl oxide and 3, 4-epoxy-1-butene. Preferred alkalis are sodium and potassium hydroxides. Suitable ketone diluents are acetone and methyl ethyl ketone. Suitable acids for neutralization of the alkali include acetic, hydrochloric, nitric, propionic and benzoic acids. In an example, a mixture of cotton linters, acetone, water, flake sodium hydroxide are stirred for 1 hour, when ethylene oxide is added and the mixture heated at 80 DEG C. for 1 1/2 hours. After neutralization of 80% of the alkali by addition of glacial acetic acid, heating is continued for 1 1/2 hours. After complete neutralization of the alkali, the hydroxyethyl cellulose is washed with aqueous acetone, then with anhydrous acetone and dried.</p> |
