Process for the preparation of functionalized polymer particles

1. 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.

2. A process as claimed in claim 1 , wherein said vinyl polymer particles are styrenic polymer particles and said further vinylic monomer is a styrenic monomer.

3. A process as claimed in claim 2 , wherein said styrenic monomer is styrene.

4. A process as claimed in claim 1 , wherein said first polymerisation initiator is selected from the group comprising organic peroxides, peroxy esters and azo compounds.

5. A process as claimed in claim 1 , wherein said organic solvent is acetone or is a portion of said monomer.

6. A process as claimed in claim 1 , wherein at least one oil-soluble inhibitor is disposed in said monomer.

7. A process as claimed in claim 1 , wherein at least one water-soluble polymerisation inhibitor is present in at least one of said polymerisation steps.

8. A process as claimed in claim 1 wherein seeds for a suspension polymerisation stage are pre-swollen.

9. A process as claimed in claim 8 , wherein seed material for a suspension polymerisation is swollen by direct addition of monomer in an amount of from 50 to 200 times the seed weight prior to effecting polymerisation.

10. A process as claimed in claim 8 , wherein seeds are pre-swollen with aminostyrene, said further vinylic monomer and, optionally, a third polymerisation initiator.

11. A process as claimed in claim 1 , wherein said aminostyrene is 4-aminostyrene.

12. A process for the preparation of monodisperse amine-functionalised vinyl polymer particles wherein said polymer particles have a mode particle diameter of at least 50 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 first 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 a second suspension polymerisation to yield a third particulate polymer seed material and using said third seed material, performing a polymerisation to yield a fourth 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 polymerisation 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 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.

13. A process as claimed in claim 12 , wherein the mode particle diameter is at least 100 μm.