Patent ID: 11939436

Abstract:
The invention concerns a method for producing a population of particles of a polymer, wherein the polymer is poly-butylene terephthalate (=PBT) or polyethylene terephthalate (=PET) or a copolymer comprising polybutylene terephthalate and/or polyethylene terephthalate, wherein the polymer is dissolved in an organic solvent which solvent is selected such that it completely solubilizes the polymer only at a temperature of the solvent above 100° C., wherein the method comprises heating the solvent and the solid polymer immersed in the solvent at least to a first temperature, at which first temperature the polymer completely dissolves, cooling the solution until a second temperature is reached at which second temperature clouding of the solution starts, further cooling the solution at a rate in a range of 0.05 ° C./min to 5° C./min or keeping the solution at the second temperature or at a temperature up to 3° C. below the second temperature for at least 5 min and then cooling the solution at a rate in a range of 0.05° C./min to 5° C./min, wherein cooling occurs at least until a third temperature is reached at which third temperature turbidity does not further increase, and separating the particles formed during step b) or c) from the solution.