Patent ID: 6777454
Filing Date: 2004-08-17
Classification: C08F

Abstract:
A process of preparing vesiculated granules of crosslinked carboxylated polyester resin, said process comprising the steps of:(a) forming a dispersion of particles of a solution in ethylenically unsaturated monomer of a carboxylated unsaturated polyester resin having an acid value of from 5-50mg KOh/g, th solution also containing water droplets which are dispersed in the presence of a base selected from: Ci) a water-soluble polyamine which contains at least three amine groups per molecule and which has a dissociation constant (pKa value) of 9.5-10.5; and (ii) a metal oxide, hydroxide or salt wherein the metal cation is chosen from the group consisting of calcium, magnesium, barium, titanium, zinc, lead, stroatium and cobalt, the salt being one wherein the pKa value of the conjugate acid of the anion is greater than 2; the dispersion additionally containing a surfactant which is free of alkylphenol moieties, and(b) initiating free radical polymerisation to cross-link the polyester and monomer and provide crosslinked, vesiculated granules, wherein: (i) where a water-soluble polyamine is used, there are present from 0.3-4.0 amine groups per polyester carboxyl group; (ii) where a metal oxide, hydroxide or salt is used, there is present from 0.8-1.8 equivalents of metal cation per equivalent of polyester carboxyl group; and (iii) the surfacant comprises a species of the formula (I) CaH2a+1â€”Oâ€”(CH2CH2O)bSO3âˆ’â€ƒâ€ƒ(1) where a is 6 to 12 and b is 2 to 8.