METHOD OF FORMING BLOWN FILM

摘要

PURPOSE:To obtain the titled film excellent in the balance of strength without using a core or the like, by cooling a high-density polyethylene melt resin tubular body extruded from an annular extrusion die by an air ring apparatus having a specified action. CONSTITUTION:After a high-density polyethylene melt resin that has been melted and kneaded in an extruder is extruded from an annular slit 2 of an annular die 1, the melt resin tubular body is cooled by an air ring apparatus 7 that has a blowing outlet 6 directed outward and upward with respect to the direction of the extrusion of the resin to obtain the intended film. Preferably, the direction of the blowing outlet 6 is tilted 5-60 deg. outward and upward with respect to the direction of the extrusion of the resin. EFFECT:High speed molding becomes possible, and a blown film can be produced inexpensively.