| 摘要 |
Water-soluble cellulose ethers are rendered more readily soluble in water by reacting them in particulate form with a polyfunctional reagent capable of forming with the cellulose ether a water-insoluble product, the reagent containing in its molecule two or more carbon atoms and two or more halogen atoms and epoxy and/or carbonyl groups which are attached to carbon atoms which are linked together either directly or through not more than four intermediate carbon atoms, the reaction being carried only far enough to increase the rapidity with which the cellulose ether can be dispersed and dissolved in water without materially reducing its solubility in water. From 0.001 to 0.2 mol. of the polyfunctional reagent may be combined per anhydro glucose unit of the cellulose ether. The polyfunctional reagent may be a dialdehyde such as glyoxal or succinaldehyde, a ketoaldehyde such as pyruvic aldehyde, or a halocarbonyl compound such as chloracetaldehyde. The cellulose ether may be suspended in a solution of the polyfunctional reagent in a liquid in which the ether is insoluble and which is inert for the ether. The suspension is agitated and the cellulose ether then filtered off and oven-dried at about 100 DEG C. Alternatively, particularly for the treatment of large quantities of carboxymethylcellulose, a 30 per cent aqueous solution of glyoxal may be sprayed on to a tumbled mass of particles of moist carboxymethyl-cellulose and the latter then dried by heating. The cellulose ether may also be treated with the reagent in vapour form while spread on a wire screen and then dried by heating. The reaction may be carried out as part of a conventional stage in the manufacture of the cellulose ether, e.g. a reforming stage or a drying stage, or during the reaction of alkali cellulose with an etherifying agent such as monochloracetic acid. In all cases the temperature and/or the period of drying are such as not to colour the cellulose ether. Additional examples of polyfunctional reagents are adipaldehyde, diketones such as butanedione-2,3 and pentanedione-2,4 dihalogenated compounds such as ethylene dichloride and dichlorobutane, dixpoxy compounds such as butadiene dioxide, and haloepoxy compounds such as epichlorhydrin and glycerol dichlorhydrin. In an example, 10 grams of a sodium carboxymethyl cellulose are agitated for 5 minutes at room temperature with 100 c.c. of an 80 per cent (by volume) alcohol solution containing about 0.2 gram glyoxal, filtered off, dried for half an hour at 105 DEG C. and pulverized to reduce the lumps formed on drying to the original fibrous form of the cellulose ether.
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