Process of manufacturing spherical polymeric beads

Claim 1

A process of manufacturing approximately spherical polymeric beads of average size less than 20 microns, which process comprises copolymerising an unsaturated carboxylic acid and a crosslinking agent characterised in that the polymerisation is initiated by means of a two part redox free radical system and is carried out in a reaction mixture comprising a fine suspension of droplets of an organic phase in an aqueous phase wherein the organic phase comprises an acid chosen from the group consisting of methacrylic acid and crotonic acid; a crosslinking agent chosen from the group consisting of divinyl benzene, divinyl toluene, divinyl xylene, divinyl chlorobenzene, divinyl naphthalene, divinyl ethylbenzene and trivinyl benzene, butadiene, isoprene, dimethallyl, diethallyl, diallyl, cyclopentadiene, piperylene, chloroprene, 2,3-dimethyl-3-butadiene, 2,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, 2,4-hexadiene, 2,5-dimethyl-2,4-hexadiene, octadiene, 3,7-dimethyl-2,4-octadiene, 2-methyl-6-methylene-2,7-octadiene, 1,3-decadiene, 1,3,5-hexatriene, hexachlorocyclopentadiene, dicyclopentadiene and divinyl-ether, and an oil soluble and water insoluble first organic oxidant part of a redox free radical initiator system; and wherein the aqueous phase comprises a solution of water, at least 15% weight inert salt per volume aqueous phase and a suspending agent which is soluble in water and not salted out of solution by said inert salt; and the second inorganic reductant part of the redox free radical initiator is at least partially soluble in both the organic and the aqueous phase and is added to the reaction mixture during the course of polymerisation while the mixture is maintained at a temperature in the range from 0°C to 50°C.