Methacrylate binders from Evonik, marketed as DEGALAN, are designed to offer multiple possibilities for the formulation of heat-sealing lacquers. They are used in the sealing of yogurt containers and pharmaceutical blister packaging.
The requirements placed on packaging coatings are high because packaging substrates can vary widely, the company said. Yogurt lids, for example, consist of aluminum or plastic; these in turn must be sealed to a variety of container materials such as polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET).
Evonik’s methacrylate experts have now succeeded in developing a new generation of heat-sealing bead polymers. DEGALAN VP P 34 reduces the complexity of coating formulation enormously because only a single binder is used and only one solvent is therefore necessary. The reason is that DEGALAN VP P 34 is a bead polymer that is easily soluble in ethyl acetate, a commonly used, highly volatile solvent for heat-sealing lacquer formulations.
DEGALAN VP P 34 based formulations can be applied directly on aluminum foil. A coating based on DEGALAN VP P34 applied on aluminum foil and sealed against PVC blister packs, has a heat seal strength exceeding 7 N/15 mm at a sealing temperature of 180 °C. For yogurt lids sealed against PS this same heat seal strength can be attained at a sealing temperature of only 140 °C.
