| 摘要 |
PURPOSE:To obtain an inflation film improved in its blocking property so as not to be curled and also excellent in transparency, by extruding a low density polyethylene into a ring shape at a specified blow ratio and a specified cooling temperature, reblowing the polyethylene under a spedified condition, and then coiling the reblown polyethylene. CONSTITUTION:A low density polyethylene (preferably having a melt index of 1-3) is extruded downwards from an extruder 1 provided with a ring die 2. In this case, the blow ratio is kept at a fixed level of 0.4-1.7 by gas inside a tube 3, and the tube is cooled from its outside by a water-cooling ring 4 kept at a fixed temperature of 20-45 deg.C. After the tube 3 passes through a space between pinch rolls 5, the folded tube 6 is reblown between reblowing pinch rolls 7 and 8 under an atmosphere kept at a temperature of 25 deg.C or lower, to make an expanded tube having a length of 2m of more. Thereafter, the tube is coiled by a coiler 11. |
