GB589984A - Improvements in the stabilization of cellulose ethers - Google Patents

Abstract

A process for the stabilization of cellulose ethers comprises dissolving the cellulose ether in a solvent liquid consisting of or comprising a polar solvent and free from substances having a degrading action on the ether, agitating the solution for at least three hours and then precipitating the ether by means of a liquid which is a non-solvent therefor but is a solvent for the liquid used to dissolve the ether. Preferably, the cellulose ether solution is stirred from 3 to 24 hours prior to precipitation and the precipitated ether is allowed to remain in the liquid for 1 to 12 hours before it is separated, washed and dried. Polar solvents specified are alcohol, pyridine and acetic acid. Solvent mixtures may be benzene and ethyl alcohol (10-50 per cent or more by weight) or ethylene dichloride and ethyl alcohol (5-25 per cent by weight). Suitable precipitants are pentane, naphtha (B.P. 100-150 DEG C.), gasoline (B.P. 50-150 DEG C.) and water. In one example, 20 parts by weight ethyl cellulose of about 45 per cent ethoxy value dissolved in about 200 parts by weight of a solvent mixture (92 per cent ethylene dichloride and 8 per cent of 95 per cent ethyl alcohol by weight) is agitated for 24 hours and the ethyl cellulose precipitated by slowly pouring the solution into high-flash naphtha (B.P. 100-150 DEG C.). After standing for 24 hours, the ethyl cellulose is separated, washed and dried. The ethyl cellulose thus prepared has improved heat resistance.