CELLULOSE ETHERS HAVING IMPROVED DISPERSING PROPERTIES

摘要

The present invention relates to cellulose ethers which can be dispersed in aqueous media and to a process for preparing them by reacting water-soluble cellulose ethers with a modifying agent. The modifying agent is a silanc, R-R4, in which R is of the formula -IMAGE-and wherein R1 is alkyl having from 1 to 4 carbon atoms, alkenyl having from 1 to 4 carbon atoms or carbocyclic aryl having one or two 6-membered rings, having up to 15 carbon atoms (including aliphatic side groups) and optionally being ring substituted by a member selected from the group consisting of chloro, bromo, alkoxy having from 1 to 4 carbon atoms, carbocyclic aryloxy having one or two 6-membered rings and up to 15 carbon atoms (including aliphatic side groups) and phenyl; R2 is -H, one of the meanings of R1 or one of the meanings of R4; R3 is one of the meanings of R2; and R4 is alkoxy having from 1 to 4 carbon atoms and being optionally substituted by a member selected from the group consisting of alkoxy having from 1 to 4 carbon atoms and carbocyclic aryloxy having one or two 6-membered rings and up to 15 carbon atoms (including aliphatic side groups); aryloxy having one or two 6-membered rings and up to 15 carbon atoms (including aliphatic side groups) and optionally being substituted by a member selected from the group consisting of alkoxy having from 1 to 4 carbon atoms and aryloxy having one or two 6-membered rings and up to 15 carbon atoms (including aliphatic side groups); aliphatic carboxylic and acyloxy having up to 5 carbon atoms, aromatic carboxylic acid acyloxy having one or two 6-membered carbocyclic rings and up to 16 carbon atoms; 0-R; or N1-1-R. The modified cellulose others can be worked into aqueous media of a broad pH range (from strongly acidic to strongly alkaline) without lump formation, the viscosity build-up of which can be precisely adjusted and controlled by simple technical means during and after the working-in phase where they are dispersed, and which (even by addition of small amounts of an appropriate modifying agent) can be converted into reversible types of modification.