METHOD FOR COOLING FILM BUBBLE OF LOW

摘要

A molten tube of low-strain hardening polymer is cooled by two annular streams of fluid contacting the outside of the tube. The fluid flows parallel to and in the same direction as the tube. The extensional viscosity index of the polymer is less than 4.5 and is a low-pressure copolymer of ethylene and at least one C3-8 alpha olefin hydrocarbon. The fluid stream are produced from rings spaced 4-15 inches apart. The lower ring pref. comprises a dual lip air ring. Blown film can be manifactured at high prodn. rates.