Focus of attention to every single detail proves worthwhile: CPP films manufactured on Brückner lines show minimal shrinkage during the aging process. Starting from the die gap of all line rolls up to the contact roll of the winder, the sensitive web is handled with extreme caution and the highest precision.
Various factors are responsible for such sensitive web handling: first and foremost, a precisely-defined web path to ensure the shortest possible free length of web path, secondly, a reduction in the number of idler rolls to a minimum to minimize stretching of the sensitive web and thirdly, the implementation of direct torque motors on all driven rolls ensuring a precise control of the web tension.
Normally, CPP film shows 1.5 % shrinkage in machine direction during the crystallization process, however, CPP film produced on Brückner lines attain a shrinkage rate of only
0.5 %. In view of the patented Brückner LIWIND® system, contact pressures below 10 N/m are possible. Therefore, CPP film of all thicknesse ranges can be wound in contact mode, achieving high-quality rolls with diameters of up to 1,200 mm.
The benefits of such low shrinkage values are primarily reflected in the superior winding quality: not only can film be wound inline with larger diameters but - last but not least - an excellent performance of all downstream processing steps, such as metallizing, slitting, printing and laminating, is ensured.
