Patent ID: 6984702

Claim:
A process for the preparation of monodisperse amine-functionalised vinyl polymer particles wherein said polymer particles have a mode particle diameter of at least 20 μm, which process comprises (a) obtaining a first particulate polymer seed material having a mode particle diameter of no more than 50 μm; (b) using said first seed material, performing a suspension polymerisation to yield a second particulate polymer seed material having a mode particle diameter greater than that of said first seed material, and using said second seed material, performing at least one further suspension polymerisation to yield a particulate polymer seed material whereby the increase in mode particle diameter in step (b) is at least ×2, wherein at least one of the suspension polymerisations effected in step (b) involves (i) forming an aqueous dispersion comprising a polymer seed material, a first polymerization initiator of an organic compound which has a molecular weight of less than 5000 Daltons and a water solubility of less than 10 −2 g/L at 25° C., a hydroxyalkylmethylcellulose stabilizer and a first monomer; (ii) allowing said organic compound to diffuse into the seed material to produce an activated seed material; and (iii) contacting said activated seed material with a second monomer and with a second polymerisation initiator while effecting suspension polymerisation thereof, and that in at least the final suspension polymerisation of step (b) the monomer comprises amino styrene, and at least one further vinylic monomer and said second polymerisation initiator is an azo compound.