MANUFACTURE OF INFLATION FILM AND APPARATUS THEREFOR

PURPOSE:To make possible to mold at high speed a resin film whose melt tension is low, by blowing air at high speeds at specified angles against a bulb of a melted resin extruded from an annular die thereby cooling the bulb. CONSTITUTION:In forming a thermoplastic resin having a melt tension of 4g or below by an inflation method into a film, against the tubular resin bulb V extruded from an annular die are blown air from an air outlet 9 of an inner air cooling ring 8 at a blow velocity of 10m/sec or more at an upward blowing angle alpha of 30-70 deg. with the axis of the bulb V, air from an outer air outlet 14 of an outer air cooling ring 13 at an upward angle beta of 70-90 deg. with the axis of the bulb V, air from a lower air outlet 15 of the outer air cooling ring 13 at an upward blowing angle beta of 70-90 deg. with the axis of the bulb V, and air from at a blow velocity of 10m/sec or more from a lower air outlet 15 of the outer air cooling ring 13 at a blowing angle alpha of 0-10 deg. with the axis of the bulb V preferably with the axis of the bulb V with the angle delta between the guide surface 16 and the die being 60-89 deg.. The ratio of the blow velocity from the lower air outlet 15 of the outer air cooling ring 13 to the blow velocity from the inner air cooling ring 8 is in the range of 1:2 to 2:1.