Process for the preparation of graft copolymers of a water soluble monomer and polysaccharide employing a two-phase reaction system

Claim 1

A process for the production of a graft copolymer of a polysaccharide and water-soluble monomer comprising the steps of: (a) suspending the polysaccharide in an organic solvent, which solvent has a boiling point at or above the temperature of the polymerization reaction, is immiscible with water and does not dissolve the polysaccharide, monomer or graft copolymer; (b) adding thereto an aqueous solution of the monomer thereby forming a suspension of discrete aqueous spheres in the organic solvent phase; (c) deoxygenating and heating the reaction mixture in the presence of a free radical polymerization catalyst to a temperature of 40 to 100° C. to initiate polymerization; (d) continuing the polymerization for from 0.5 to 6 hours; and (e) isolating the resultant graft copolymer from the reaction mixture in the form of solid beads; wherein it is required that either the aqueous solution or the polysaccharide suspension or both contain a cationic, anionic or nonionic surfactant, that the solids content of the aqueous polymerization mixture is greater than 50% by weight, and that the polysaccharide be present in the final graft copolymer in an amount of from 10 to 90% by weight.