Manufacturing methods, based on non aqueous dispersion techniques, to produce spherical polyester particle size distributions and tailorable mean particle sizes

A process for preparing spherical, polyester particles having a mean particle size of between 1 to 200 μm and a particle size distribution with a span (=d90−d10/d50)<1.5, comprising the following steps:

• A. producing a melt of the starting monomers or oligoesters for polyester
• B. slowly adding the molten starring materials for the polyester to a rapidly stirred inert high-boiling heat transfer medium at a temperature which is at least as high as the softening temperature of the starting materials, in the presence of at least one polymeric dispersion stabilizer, and
• C. then heating of the reaction mixture to a temperature in the range from 120 to 280° C., with simultaneous removal of the condensation byproducts, until the polyester has the desired molecular weight;
• D. optionally subsequent addition additives, if desired, at a temperature in the range from 25 to 220° C.;
• E. thereafter cooling the reaction mixture to a temperature within a range which is below the softening temperature of the polyester and separating off of the resulting colorless spherical polyester particles and washing off the residual heat transfer medium with an inert, volatile solvent and drying of the resulting powder.