Release Liners – Silicone Coatings
Silicone is a material based on polydimethyl siloxane, and to be effective against adhesives it needs to be fully cross linked and anchored to the substrate to prevent migration which will destroy the adhesive properties. This is normally achieved by adding functionality to the siloxane polymer, normally a reactive group such as vinyl (thermally cured) or acrylate or cycloaliphatic epoxy groups (UV/EB curing).
Silicone has release properties because of its very low surface energy (about 24 dynes/cm) and its rubber like nature and these characteristics combine to encourage adhesive materials to break away from the silicone. The force required to remove the adhesive will vary according to a large number of variables, but easy release will only occur if the adhesive silicone contact is broken in incrementally small amounts and the type of silicone used can influence this by achieving strain relief as the laminate is pulled apart.
By combining formulations it is possible to produce a product with easy release one side and tight release on the other (differential release) and when an adhesive is cast onto the tight release side and the product wound up, it is likely to stay on the same side when the roll is unwound. This is normal for a 2 side adhesive tape, the trick is to make the tight release easy enough so when the adhesive is in place on the product the liner can be removed to expose the other adhesive surface for mounting or closure purposes. Contact Us Page