Abstract: This article introduced the process procedure of 2-layer co-extrusion blown film technology of TPU/PE and the specific requirement of TPU on screw, die, dual-lip air ring, haul-off and winding. As a conclusion, to quickly extrude and haul-off TPU, one needs to use not only a bimetal and mixing screw of φ75×30, compression ratio of 2.2 to process TPU and a barrier screw of φ75×30, compressio ratio of 1.8 to process PE, but also a 2-layer co-extrusion central-fed die with a lip diameter of 500 mm. This co-extrusion technology can overcome the low efficiency in processing of TPU when using normal screw. The study indicated that TPU and PE from M2B-1700QA blown film line in suitable configuration showed good quality in plasticizing, with a maximum output of 250 kg/h, and a thickness of TPU film of 0.015～0.1 mm, while the MD and TD tolerance can be controlled within ±8 %.

Key words: thermoplastic polyurethane, polyethylene, two-layer film, co-extrusion blowing