Patent ID: 6770702
Filing Date: 2004-08-03
Classification: C08F,C09D,Y10S

Abstract:
A polymer microparticle dispersed in an aqueous phase and with a fully crosslinked exterior, obtained by a multistage polymerization process which involves conductinga) in a first step, an aqueous-phase polymerization of a monomer mixture comprising i) from 7.5 to 93% by weight of at least one ethylenically monofunctional compound; ii) from 0.3 to 47.5% by weight of at least one ethylenically difunctional or polyfunctional compound; in the presence of a polymer selected from a polyesterpolyol having a number-average molecular weight of from 500 to 10,000, an acid number of between 22 and 224, and an OH number of between 60 to 400; polyurethane having a number-average molecular weight of from 500 to 20,000, an acid number of between 25 and 150, and an OH number of between 50 to 350, said polyurethane containing on average per molecule at least one free carboxyl group originating from a polyesterpolyol; and polyacrylate having a number-average molecular weight of from 2,000 to 100,000, an acid number of between 25 and 300, and an OH number of between 50 to 250; b) in a subsequent step, a reaction of the product obtained from step a) with iii) from 5 to 85% by weight of at least one ethylenically monofunctional compound; the sum of the fractions of components (i) to (iii) being 100% by weight; followed by a reaction of the product obtained from step b) with a crosslinker.