The production process of PVC films at the Worms site
1. Film manufacture and basic material processing
We produce our PVC films as sheets in 4-roll calenders. The components required for the process, such as powders, liquids and pigments are dosed computer-controlled and evenly combined in a precision mixer.
In an extruder the plastic molding compound is preplasticized and then the so-called rough sheet is manufactured in a rolling mill with two heated rollers moving opposite in rotation. Then a strip is cut and conveyed to the first roll gab of the calender.
The calender, usually consisting of four separately driven, heated rolls then homogenizes, degasses, and forms the plasticized compound. After the material has passed three roll gaps, the film is stripped off from the last calender roll over a steel roller. The embossing station then applies the grain to one side of the film.
Subsequently, the plastic film is cooled down step-by-step over several cooling rolls. After the final thickness control, the edges are trimmed and the film is rolled.
2. Printing
RENOLIT generally uses the rotogravure to print its films. With this method the print image is engraved in the shape of small scoops onto the printing roller. A scoop roller applies the print color onto the print roller. Subsequently, this paint is „wiped off“ with a doctor blade to ensure that the paint only fills the scoops on the printing roller. A rubber roller, the so-called “impression roller” presses the film against the printing roller and thus empties the scoops. For decorative design printing, the films must - depending on the pattern - run through several printing stages to create the desired appearance. Eventually, the printed film is dried.
3. Embossing and laminating
An embossing roll and a rubberized smooth mating roll imprint one side of the film with a grain. During the lamination process either two PVC sheets (double lamination) or three PVC sheets (triple lamination) are thermally heat-sealed by means of a heating cylinder and are subsequently embossed. |
