| 摘要 |
<p>PURPOSE:To obtain the title uniform tubular film having improved stretchability without causing air stayed between a film and a mandrel, by adjusting the cooling rate of the polyhexamethylene adipamide film in molding at a temperature of 250 deg.C to 150 deg.C to a specific range. CONSTITUTION:Polyhexamethylene adipamide resin melted at 280-300 deg.C is extruded from a ring die and cooled while being in contact with and slid along an inside mandrel placed at the center of a circular slit of the die slit. The cooling rate x( deg.C/sec) of the resin film, whose temperature is reduced from 250 deg.C to 150 deg.C, is maintained in a range satisfying the formula (etarel is a relative riscosity of the polyhexamethylene adipamide resin measured by using a 1g/100ml solution in 96% sulfuric acid at 25 deg.C). The cooling rate is controlled by the material and temperature of the inside mandrel, the flow rate of a coolant cooling the inside mandrel internally, the film temperature before coming into contact with the mandrel, etc.</p> |
