PURPOSE: To produce the mark film having high transparent and uniformity of thickness by stretching the polyamide thermoplastic sheet at the soft state, after the streamer corona discharge was applied.
CONSTITUTION: The polyamide thermoplastic film containing 0.01W10wt% of the inorganic particle smoothing agent (the average particle diameter 0.01W10μ) is pushed out from the die 1 as the softened sheet, and the streamer corona discharge 8 is applied between the sheet 2 and the electrode 7 with DC high voltage from the source 6. After the sheet is colled down in the temperature range of the max. temperature of crystalization -20°C and the dew point, with the cooling drum 3. The unstretched sheet 5 is stripped off by the stripping drum 4 and then is stretched at least more than 1.1 times in the slow and high speed rollor groups 9, 10.
NISHIMURA FUMIO
WATANABE HARUHIKO
KOBAYASHI MASAHIRO
TAKEUCHI KUNIO
OKUDAIRA HARUO
