| abstract |
Vesiculated beads having improved scattering efficiency and resistance to shrinkage are prepared by a process which comprises: n (a) forming in the presence of a polyamine, as a water-in-oil emulsion, a stable dispersion of droplets of water in a solution of a carboxylic acid functional unsaturated polyester resin having an acid value of 8 to 20, and at least one ethylenically unsaturated monomer copolymerizable with the polyester; and n (b) forming in an aqueous solution, as a water-in-oil-water emulsion, a stable dispersion of the globules of the droplet-containing amine neutralized solution of the carboxylic acid functional unsaturated polyester and copolymerizable monomer; and n (c) polymerizing the polyester and copolymerizable monomer by free radical addition polymerization thereby producing granules of opaque, cross-linked vesiculated beads; n wherein the polyamine contains at least 3 amine groups per molecule; and wherein the amine is present at a concentration such that there are at least about 2.0 amine groups per each carboxylic acid group. |