GB601796A - Apparatus and process for pressing plastic sheeting - Google Patents

Abstract

<PICT:0601796/IV(a)/1> A sheet 27 of thermoplastic resinous material is planished or embossed by introducing it between a stainless steel or chromium plated steel planishing belt 21 and a revolvable drum 10, the belt being pressed against the drum by an endless tension band 11. Resiliently-mounted, arcuate heating shoes 31 heat the material nearly to its softening temperature during the first part of its travel over the drum and cooling shoes 35 cool the material, before it leaves the belt, to a temperature less than that at which it adheres to the belt. Another planishing belt 29 may be introduced between the material and the drum. The drum may be heated by hot water, but is kept at a temperature below that to which the material is cooled. Insulation 34, such as cloth padding, prevents heat flow from and to the drum. The belts have a small heat capacity so that they are readily heated and cooled. Additional pressure may be applied to the material at selected areas by a roller 18, which pressure may be regulated by a cam 19. The guide rollers of the planishing and tension belts are journalled in movable bearings, to allow the planishing belts to be kept taut and to adjust the pressure applied by the tension band. The process frees sheets from internal strains imposed by calendring. Decorated thermoplastic sheeting may be made by feeding coloured or decorated strips of thermoplastic material in contact with the sheeting. A product resembling patent leather may be made by using sheeting of plasticized vinyl chloridevinyl acetate copolymer containing a small amount of carbon black. The thermoplastic sheeting may be composed of plasticized polyvinyl chloride, cellulose acetate, cellulose nitrate, cellulose acetobutyrate, polymethylmethacrylate, polyvinylidene chloride or polystrene. The Specification as open to inspection under Sect. 91 comprises also the feeding and removal of the sheeting coincidentally to or from both surfaces, i.e. the drum and a planishing belt or two planishing belts, to prevent buckling, wrinkling and slipping of the sheeting. This subject-matter does not appear in the Specification as accepted.