Abstract: An apparatus for making an inflation film formed by extruding a raw resin in a molten state through a circular die to form a tubular film, and expanding the tubular film by the pressure of a gaseous medium introduced into an inner space thereof, while the tubular film is being cooled. The apparatus includes a cooling ring, at least one air ring coaxial with the circular die, and an adjusting device for adjusting the temperature of a gaseous medium, blown from the air ring, to a range effective to retain the tubular film, then still in a molten phase, in a condition in which the tubular film is inflated. A method for making an inflation film is also disclosed.

Abstract: An inflation film is formed by extruding a raw resin in a molten state through a circular die to form a tubular film, expanding the tubular film by the pressure of a gaseous medium introduced into an inner space of the tubular film, while the tubular film is being cooled to be solidified by blowing a cooling gas to the outer surface of the tubular film, and drawing the film while being progressively flattened by guide members. During the manufacture, the temperature Tf (° C.) of the solidified tubular film at the time it contacts the guide member for the first time is so adjusted as not to be higher than Tr (5) [° C.]; wherein Tr (5) represents the temperature at which the thermal deformation ratio of the solidified tubular film becomes 5% when it is measured, being loaded with a stress of a value equal to the frictional force received from the guide members under the conditions of manufacture of the film.

Abstract: An apparatus for making an inflation film formed by extruding a raw resin in a molten state through a circular die to form a tubular film, and expanding the tubular film by the pressure of a gaseous medium introduced into an inner space thereof, while the tubular film is being cooled. The apparatus includes a cooling ring, at least one air ring coaxial with the circular die, and an adjusting device for adjusting the temperature of a gaseous medium, blown from the air ring, to a range effective to retain the tubular film, then still in a molten phase, in a condition in which the tubular film is inflated. A method for making an inflation film is also disclosed.

Abstract: An inflation film is formed by extruding a raw resin in a molten state through a circular die to form a tubular film, expanding the tubular film by the pressure of a gaseous medium introduced into an inner space of the tubular film, while the tubular film is being cooled to be solidified by blowing a cooling gas to the outer surface of the tubular film, and drawing the film while being progressively flattened by guide members. During the manufacture, the temperature Tf (° C.) of the solidified tubular film at the time it contacts the guide member for the first time is so adjusted as not to be higher than Tr (5) [° C.]; wherein Tr (5) represents the temperature at which the thermal deformation ratio of the solidified tubular film becomes 5% when it is measured, being loaded with a stress of a value equal to the frictional force received from the guide members under the conditions of manufacture of the film.