EXTRUSION COATING PROCESS

摘要

The invention is concerned with a direct extrusion process for preparing a coating substrate from a viscous coating composition. The process of the invention comprises feeding the component material or materials of a coating composition into an extruder having a barrel and an elongated extrusion die orifice leading away from the barrel and advancing the material or materials forward in the extruder barrel to obtain a molten homogeneous composition, and then through the extrusion die orifice. A substrate is directed into positive engagement with the outlet opening defined by the extrusion die and the homogeneous composition is extruded through the extrusion die orifice onto the substrate to force the substrate away from the die and to form a uniform coating on the substrate. The coated substrate is then moved into immediate contact with a closely disposed coating roll. The substrate is drawn to the die orifice from a direction such that the angle ? formed between a line representing the direction of approach of the substrate and a line representing the direction of extrusion is less than 90.degree., whereas the coated substrate is drawn away from the die orifice in a direction such that the angle ? formed between the direction of extrusion and a line representing the initial departing direction of the coated substrate immediately on formation when combined with the angle ? is less than 180.degree.. The invention is particularly useful in the manufacture of viscous pressure-sensitive adhesive sheets and tapes.