Patent ID: 7540962

Claim:
Method of preparing spheroid polymer particles having a narrow particle size distribution by dispersion according to the ratio F≦2, wherein F=dp(%<90)/ dp(%<10), wherein dp is the particle diameter in microns and wherein dp(%<90) and dp(%<10), respectively, designate the top-limit for a group of particles and the bottom-limit for a group of particles, with dp(%<90) being a value of a particle size below which 90% of the particles are smaller in size, and, dp(%<10) being a value of a particle size below which 10% of the particles are smaller, such particles made by dispersion polymerization which comprises the steps of: providing a two-phase system in the form of a dispersion comprising an organic phase of droplets dispersed in an aqueous medium containing a dissolved salt by mixing said organic phase in said aqueous medium under agitation and forming said droplets with less than 0.1 wt. % or without using a dispersion stabilizing agent to stabilize the dispersion, wherein the organic phase comprises at least a crosslinkable monomer, a polymerization initiator and an organic solvent for said monomer; and allowing the crosslinkable monomer to polymerize, while the two-phase system is agitated without adding of additional organic phase during said polymerization.