| 摘要 |
PURPOSE:To obtain high-speed film making properties superior in transparency, shock resistance and stretchability by improving cooling liquid injecting direction, by a method wherein an inside cooling liquid circulating spiral groove cooling from a ring part is provided on the inside of a pipe diameter controlling ring and the spiral groove is provided successively to the lower part than the ring further. CONSTITUTION:An annular die 1 is fitted downward to an extruding machine, a thermoplastic resin melted by an extruding machine is extruded downward into a tubular state through an annular slit 3 by passing through a resin passage 2 on the inside of the die 1. In a direct cooling inside molding tool 5 cooling the tubular melted thin film 4 from the inside by using the inside molding tool 5 together with an outside annular cooling tank, inside cooling liquid circulating spiral grooves 9, 11 cooling a pipe diameter controlling ring part from the inside are provided on the inside of the ring part. A spiral groove 12 is provided successively on the inside of the pipe diameter controlling ring 6 from here further. Those grooves 9, 11, 12 are constituted so that a cooling liquid is supplied to those grooves 9, 11, 12, which flows down along the groove. |
