Abstract: Process and apparatus for producing a sheet or film exhibiting a colored band of varying color intensity, with an extruder for melting a stream of a thermoplastic synthetic resin and with a slot die tool (e.g.

Abstract: A slot die apparatus for the coextrusion of an endless sheet having a thickness of about 0.1-5 mm with an optionally dyed edge strip made from a narrower, optionally colored, melt stream of a width of about 100-500 mm and from a broader melt stream of a width of about 1,000-3,000 mm of a thermoplastic synthetic resin is provided by means of two parallel-operating extruders and associated melt pumps, with merging of the two melt streams. The apparatus is also provided by flanging together, by means of a flange, two dies at their end faces, these dies having identical cross sections and a corresponding width, comprising a spreader block, deckle, bottom lip, and top lip, and a flow channel made up from these components.

Abstract: A process for extruding a film having small variations in thickness by regulating the quantities fed to a worm press and by regulating the extrusion process. Marginal strips and waste products of extruded film are re-processed by returning these materials, slicing them and directly weighing them before being fed to the filling bin of the screw press. In order to regulate the quantities fed to the screw press, the weighed material per unit of time is continually subtracted from a nominal value set by a volume regulator associated with the raw material seeder devices. The filling degree of the screw press is measured as the mass pressure between the screw press and a constant volume pump such that the filling degree is maintained constant during the extrusion process.