Patent ID: 7022762

Claim:
Method of preparing, by free radical emulsion polymerization, of ultrafine hydrophobic latex polymer or copolymer particles in order to polymerize or copolymerize monomers or monomer mixtures respectively, of at least one purified compound as a chain transfer agent (CTA), wherein said latex particles have an average particle size of less than 90 nm, being at least 10% lower than if prepared in the absence of said CTA, wherein said polymerization is conducted in a water-based reaction in the presence of a chain transfer agent and of a surfactant, wherein said surfactant is present in a concentration versus said monomer or monomer mixture of from 5 up to 25% by weight for a non-ionic surfactant or from 0.05 up to 10% by weight for an ionic surfactant wherein said CTA is a water-soluble oligomer having surface-active graft copolymers with a hydrophilic graft and a hydrophobic main chain.