Process for preparing bead polymers

Claim 1

A process for preparing a water-soluble bead polymer comprising: (a) forming an aqueous monomer solution containing 60% to 90% by weight of a monomer selected from the group consisting of: (1) a compound of the general formula I ##STR5## wherein R 1 is hydrogen or methyl, R 2 and R 3 may be the same or different and each is linear or branched alkyl of from 1 to 4 carbon atoms, R 4 is hydrogen, linear or branched alkyl of from 1 to 8 carbon atoms, hydroxy alkyl of from 1 to 4 carbon atoms, or benzyl, Y is alkylene or hydroxylalkylene of from 2 to 4 carbon atoms, and X - is an anion, and (2) a mixture of the compounds of the formula I and a water-soluble vinyl monomer copolymerizable with the compound (I), wherein this compound of of formula I is from 50 up to 100 mol % of the total amount of the monomers; (b) dispersing said aqueous monomer solution as droplets in a dispersion medium which is non-compatible with the aqueous monomer solution and which is inert under polymerization conditions, said dispersion medium containing, as a dispersion stabilizer, 0.05 to 10% by weight of a cellulose ester or a cellulose ether which is insoluble in water but soluble in the dispersion medium; and (c) polymerizing the monomer in the droplets at a temperature of from 40° C. to the temperature at which the dispersion medium boils, in the presence of a free radical polymerization initiator and in the absence of oxygen.