Abstract: A method for producing a resin sintered body 1 by applying an ink 3 to thermoplastic resin powder 2 and sintering the powder, the method including the step of immersing an intermediate resin sintered body 1m, which has an unevenly colored region on the surface thereof and the whole of which has been already sintered, in a surface treatment liquid containing sulfuric acid and chromic anhydride, in which the concentration of chromic anhydride is 300 g/L or more, for 5 minutes or longer. When producing a resin sintered body by sintering thermoplastic resin powder, the surface of the resin sintered body can be evenly and sufficiently colored to an extent required without an unevenly colored region on the surface thereof, and also the surface of the resin sintered body can have a good appearance and smoothness.

Abstract: A process is disclosed for producing powdery polycarbonate from a polycarbonate solution which comprises:(a) charging the solution into the feed opening of a disolvating apparatus, the apparatus being composed of a casing and having at least two screws incorporated therein, the screws meshing with each other; the apparatus comprising two parts; a evaporating zone and a powdering zone; a space being provided above the screws in the evaporating zone, the space extending in the axial direction of the screws and having at least one degassing opening, and side and bottom portions of screws generally fitting with the casing in the evaporating zone; top, side and bottom portions of screws generally fitting with the casing in the powdering zone, heating means being installed in the casing and/or screws;(b) in the evaporating zone, evaporating the solvent of the polycarbonate solution using the heating means while moving the solution by the screws;(c) powdering the dried polycarbonate in the powdering zone; and(d) dis