Polyvinyl pyridine microspheres

Claim 1

A composition consisting essentially of discrete beads, at least 80% of which have a uniform diameter from 100 A to 60 microns having a surface area of at least 1 m 2 /g and consisting essentially of addition copolymerized monomer mixture containing 60 to 80% vinyl pyridine, 10 to 30% of an addition copolymerizable, water soluble, monounsaturated comonomer selected from acrylamide, methacrylamide, acrylic acid, methacrylic acid or compounds of the formula: ##STR2## where R 1 is hydrogen or lower alkyl of 1-8 carbon atoms; R 2 is alkylene of 1-12 carbon atoms and Z is --OH or ##STR3## where R 3 or R 4 are individually selected from H, lower alkyl or lower alkoxy of 1-8 carbon atoms, and 5 to 30% of a water soluble, addition copolymerizable polyvinyl cross-linking agent said beads including a hard, cross-linked, hydrophobic vinyl pyridine copolymeric core and a hydrophilic, monounsaturated comonomer copolymeric sheath.