Particles of thermoplastic polymer, and process of making the same

Finely comminuted particles of a normally solid thermoplastic organic polymer, which is particularly useful as a toner base for electrostatic reproduction utilizing pressure fusing on the toner, is prepared by dissolving a polymer in a normally solid first solvent, cooling the resulting solution to form a friable solid, and removing the first solvent from the solid, preferably by extraction with a normally liquid, relatively volatile, second solvent in which the polymer is substantially insoluble. When using the process to make magnetic mono-component toners, powered magnetic material and/or carbon black or other pigment are added to the solution of polymer and first solvent.