Control Release Additives and Peel Release Values of Silicone Release Coatings

Most release coatings are silicones, usually crosslinked PDMS-type materials. Silicones dominate the market: they have excellent anti-stick properties. These properties originate from the a low surface tension of silicones and flexibility of Si-O-Si bond.1 Industry uses test tapes to measure an important property of silicone release coatings or silicone liners, the peel release value (PRV). PRV is the force required to peel an adhesive from a release liner and is traditionally measured in g-force/in: N/m or kg/s2 in SI system. Popular test tapes used in the industry are 610 tape of 3M and Tesa®’s 7475 or 7476 tapes. In our experience, Tesa®’s 7475 gives more reliable results with lower standard deviation than 610 tape.

PRV strongly depends upon configuration of the peel tester during measurements: the angle of a peel, rate of peel, preparation and conditioning of the sample consisting of the liner with an adhered test tape.

Another property of interest is adhesion of the silicone coating to PET. Upon delamination of release liner the silicone coating should not be transferred to the label or a window film. In other words, adhesion of release coatings to PET should be rather strong. We were looking for a quantitative method of such adhesion determination.