Process for the production of dyed, flat articles from thermoplastic

Abstract

A process for the production of homogeneous flat articles of thermoplastic synthetic resins wherein a starting mixture based on thermoplastic synthetic resins is processed into agglomerate or granulated material by a thermal pretreatment above the softening temperature and subsequently, optionally after additional intermediate steps, is mechanically comminuted to a mixture of particles having a random grain size distribution. The mixture of particles is piled continuously onto a conveyor belt to form a uniform layer and is sintered, under the action of heat up to the plasticization of the thermoplastic synthetic resin, into a coherent flat articles and is then press-molded under the effect of pressure and heat. The pourable powders or particles are formed from a blend of differently colored agglomerates or granules prepared in a predetermined mixing ratio; the blend being obtained from several colored batches of thermoplastic resin, each batch having a different color from the other and each batch being heat treated above the softening point of the thermoplastic resin. In one variation of the process, at least one liquid or pourable, meltable, colored medium is applied in predetermined patterns and penetrates into the sintered layer up to a desired depth, in particular throughout the entire layer thickness; and thereafter the dyed, sintered layer is compressed under the action of pressure and heat into a compact flat article.