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US 8,912,251 B2Granted
Process of heat treating structured polymer particles
AssigneeOMNOVA Solutions Inc.
InventorsMelinda H. Keefe, James G. Galloway, Ray E. Drumright, Michael J. Devon, Dwayne J. Nicholson
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Abstract
A process comprising heating an aqueous dispersion of first structured polymer particles at a temperature of at least about 155° C., optionally in the presence of a base and/or a swelling agent, to produce an aqueous dispersion of heat treated structured polymer particles.
Claims15
A process for producing an aqueous dispersion of hollow particles, the process comprising the steps of:
- a. forming a plurality of polymer particles that are swellable upon neutralization or hydrolysis;
- b. encapsulating the plurality of polymer particles by polymerizing monomer including styrene at a temperature of 50° C. to 80° C. to thereby form a plurality of core-shell particles;
- and
- c. heating the core-shell particles to a temperature of 140° C. to 200° C.
- d. cooling the polymer particles from the peak heat treatment temperature to a temperature at or below the Tg of the shell polymer at a rate of not greater than about 2° C. per minute.
2 more elements
Dependencies are inferred from the claim text.