A method that includes coextruding two or more thermoplastic resin streams through a profiled die plate, which die plate is shaped to form a nonplanar film (three dimensional) preferably with a regularly oscillating peak and valley structure that oscillates from a top surface to a bottom surface forming...http://www.google.de/patents/US7678316?utm_source=gb-gplus-sharePatent US7678316 - Coextruded profiled webs
