CHEMICALS USED IN INDUSTRY AND SCIENCE, IN PARTICULAR POWDERS OF PLASTIC FOR THE CONSTRUCTION OF OBJECTS IN A LAYERWISE FASHION BY MEANS OF SELECTIVE THERMAL SOLIDIFICATION; UNPROCESSED ARTIFICIAL RESINS FOR LAYERWISE GENERATIVE BUILDING OF OBJECTS BY SELECTIVE THERMAL SOLIDIFICATION; UNPROCESSED PLASTICS; CERAMIC COMPOUNDS IN GRANULES AND POWDERS FOR THERMAL SOLIDIFICATION