GB792611A - Preparation of water-soluble sulphonation products from copolymers of úßú�-vinyltoluene and acrylonitrile - Google Patents

Abstract

Water-soluble resin sulphonates are prepared by forming a substantially homogeneous dispersion in liquid sulphur dioxide of a copolymer of from 90 to 98 per cent of ar-vinyl toluene and correspondingly 10 to 2 per cent of acrylonitrile, mixing the dispersion with a total of at least 0.7 molecular equivalent of a sulphonation agent per molecular equivalent of monomeric compounds chemically combined in the copolymer, the sulphonation agent consisting of from 10 to 90 mol. per cent chlorosulphonic acid and correspondingly from 90 to 10 mol. per cent sulphur trioxide in the presence of liquid sulphur dioxide as a reaction medium, the proportion of sulphur dioxide being such that the resin sulphonate is not more than 5 per cent of the whole mixture, and maintaining the mixture at a temperature not higher than 40 DEG C., the starting copolymer being one whose solution in nine times its weight of toluene has a viscosity in centipoises at 25 DEG C. not greater than that represented by a point on the line DEF, and preferably the line ABC, correspond<p/1>ing to the mol. per cent chlorosulphonic acid in the sulphonation agent. The resin sulphonates thus produced may be converted into salt form by treatment with ammonia or alkali metal hydroxides. In the examples the vinyl toluene used to form the copolymers was a mixture of the meta and para isomers.