 |
|
Sensitive Processing
“Photosensitive sheets made of styrene-isoprene-styrene block copolymer (SIS) with a thickness of 1 to 7 mm are produced for offset printing,” explains Marco Schnek, Sales Engineer for Film and Sheet Extrusion Lines at KraussMaffei Berstorff. “These sheets are covered with a printing film that is provided with a cut-out in the area of the pattern to be printed. Cross-linking of the material is then produced by ultraviolet light applied to the area in question. After the non-cross-linked material has been chemically washed in a final step, the printing sheet with the desired printing pattern is finished. This printing sheet can be used for wide variety of products,” adds Marco Schnek.
The production of these sophisticated sheets requires in-depth process and processing know-how. Throughout the entire production process up to cross-linking, the sheets are extremely susceptible to deformation. This is why they are covered with protective film on both sides after the extrusion process and must be handled with utmost care during processing. Homogeneous mixing of all components within the extruder, highly sensitive melt passage and controlled sheet cooling to the final temperature without any warping are additional challenges to be met. “The processing of low-viscosity, sticky and temperature-sensitive melts involves high demands on the entire extrusion line – in particular in view of the wide thickness range required in offset printing with a tolerance of +/- 1%,” declares Marco Schnek.
KraussMaffei Berstorff GmbH. |
|