Simulation with Silicone
For pressure-sensitive-adhesive (PSA) labels to function properly, the release coatings, adhesives and backing materials must be optimally matched and must suit the industrial processing conditions. WACKER tests this out in its new DEHESIVE® Coating Center.
Before the labels are dispensed, the die-cut paper between the labels – the matrix – is pulled off at high speed. With the DEHESIVE® SFX silicones, the release force remains low, even during high-speed peeling. There is thus no risk of matrix tearing.
Not all labels are the same. While product information should permanently adhere to a shampoo bottle, the price label on a water melon must peel off easily. Different adhesive mixtures make specific applications of self-adhesive materials possible, but also present the coatings industry with the challenge of providing a constant stream of new, modified silicone formulations for release liners. In addition, the substrate itself and subsequent processing play a role in deciding the composition of the release coating. For automated dispensing of labels, for example, it is important that the paper lattice between the individual labels – the matrix – can be pulled off easily without tearing or removing the labels from the backing material as well.
At WACKER’s DEHESIVE® Coating Center in Burghausen, engineers work on a 380-square-meter area to simulate industrial processing conditions for silicone release coating and to devise coating solutions to meet various requirements.
Testing and Optimizing
The center combines a pilot coater, a test lab and a large selection of base papers and films typical of the industry under one roof. “The pilot plant allows us to simulate our customers’ coating conditions and to test DEHESIVE® release formulations on the desired substrate and then optimize it,” explains Dr. Hans Lautenschlager, who is in charge of technical support for silicone release coatings at WACKER. The team led by Lautenschlager is currently testing formulations for seven different substrates supplied by a US partner. There is a choice of 30 silicone polymers and five crosslinking agents available for the coating. Depending on their composition, the individual formulations vary with regard to flow properties, release force and curing rate.