Emulsion method for the manufacture of ultra-fine spherical polymer particles

1. A method for making spherical polymer particles, the method comprising:

providing a polymer solution comprising a polymer in an amount of 10% by weight or higher, and an organic solvent;

combining the polymer solution, deionized water, and a first surfactant, to form an emulsification composition having an organic solvent fraction of 0.75 or higher by volume;

forming an emulsion from the emulsification composition; and

adding the emulsion into deionized receiving water maintained at a temperature above the boiling point of the organic solvent for a period sufficient to evaporate the organic solvent, wherein the adding and the evaporating are at a rate effective to form an aqueous slurry comprising spherical polymer particles having a Dv100 (volume-based diameter) of 10 micrometers or less, as measured by laser diffraction and having an average sphericity of 0.85 to 1.

2. The method of claim 1 , wherein the polymer is a thermoplastic polymer.

3. The method of claim 1 , wherein the polymer is a polyetherimide, a polyarylene sulfone, or a polycarbonate.

4. The method of claim 1 , wherein the organic solvent has a boiling point of less than 90° C. and is immiscible with water.

5. The method of claim 1 ,

wherein the first surfactant is an anionic surfactant, cationic surfactant or non-ionic surfactant, or a combination comprising at least one of the foregoing.

6. The method of claim 1 , wherein forming the emulsion is by agitating the emulsification composition.

7. The method of claim 6 , wherein the agitating is under high shear at 7,000 to 10,000 rpm for 2 to 5 minutes.

8. The method of claim 1 , wherein the receiving water comprises a second surfactant, an anti-foaming agent, or both.

9. The method of claim 1 , wherein the emulsion is added to the receiving water in the form of droplets.

10. The method of claim 1 , further comprising heating the emulsion to up to 100° C. before adding the emulsion into the receiving water.

11. The method of claim 1 , wherein the aqueous slurry further comprises an additive composition comprising a stabilizer, a colorant, a filler, a polymer latex, a coalescing agent, a cosolvent, a third surfactant different from the first surfactant, or a combination including at least one of the foregoing, each in an amount from 0.1 to 10 total weight percent.

12. The method of claim 1 , further comprising isolating the formed spherical particles.

13. The method of claim 12 , further comprising

filtering the formed particles from the receiving water to provide filtered particles;

washing the filtered particles in water to provide washed particles; and

drying the washed particles at a temperature of 80° C. to 210° C., with or without the use of vacuum.

14. The method of claim 1 further comprising combining the spherical polymer particles with an additive comprising a particulate filler, antioxidant, heat stabilizer, light stabilizer, ultraviolet light stabilizer, UV absorbing additive, NIR absorbing additive, IR absorbing additive, plasticizer, lubricant, release agent, antistatic agent, anti-fog agent, antimicrobial agent, colorant, laser marking additive, surface effect additive, radiation stabilizer, flame retardant, anti-drip agent, a fragrance, a fiber, or a combination comprising at least one of the foregoing.

15. The method of claim 1 , further comprising combining the spherical polymer particles with a flow promoter in an amount of 0.001 to 1 weight percent, based on the weight of the spherical polymer particles.