Patent ID: 11939446
Assignee: NOURYON CHEMICALS INTERNATIONAL B.V.
Field: Chemical engineering (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 20:
21. A process for the manufacture of thermally expandable thermoplastic microspheres, the process comprising:
providing a mixture of monomeric materials suitable for polymerisation to form a thermoplastic polymer and at least one blowing agent,
providing a colloidal silica that is surface-modified with at least hydrophobic organosilane groups;
contacting the mixture of one or more monomers and at least one blowing agent with the surface-modified colloidal silica and forming an o/w emulsion comprising droplets of the mixture of one or more monomers and the at least one blowing agent in an aqueous phase; and
polymerising the one or more monomers in the droplets to form an aqueous slurry and/or wet cake of thermally expandable thermoplastic microspheres,
wherein the colloidal silica is modified with propylsilyl and glycerolpropylsilyl groups,
wherein the mixture of monomeric materials comprises acetonitrile, methylmethacrylate, and vinylidene chloride,
wherein the at least one blowing agent comprises isobutane, and
wherein the emulsion further comprises a cross-linker comprising trimethylolpropane-trimethacrylate, trimethylolpropane tri-acrylate, or combinations thereof.