ABSTRACT
Label stock manufactured on a one-station coater might require two or three passes to complete the manufacturing process. Pressure-sensitive adhesives are coated either directly or by transfer. When direct coating, pressure-sensitive adhesives (PSAs) are coated directly on the final web material. High peel forces are necessary to separate water-based acrylic PSA labels from Sn-catalyzed silicones. Only addition polymerization with a Pt catalyst allows lower release forces. The choice between direct or transfer coating influences the penetration and anchorage of the adhesive as well as the release force. Knife and blade coaters obtain their nomenclature from the application systems. These machines are employed to deposit thick coating layers with at least 50% solids content. Knife coaters employ a rigid blade that has sharp or rounded edges, while the blade coater utilizes a thin spring-like doctor blade. Both machines are similar but different coating reservoirs, tension, and drying and wiping systems.
