PREPARATION OF ROD OR PIPE OF POLYOXYMETHYLENE HIGH ELASTIC MODULUS

摘要

PURPOSE:To obtain a polyoxymethylene rod or pipe having a tensile elastic modulus 25GPa or more at a high preparing speed by heating dielectrically and stretching the rod or pipe under specific conditions of ambient temperature, field strength, delivery speed, speed ratio. CONSTITUTION:The maximum ambient temperature in a heating furnace is set at 120-170 deg.C and made gradually higher from the inlet of the furnace to the outlet thereof. The polyoxymethylene rod or pipe 1 supplied into a dielectric heating unit 4 undergoes dielectric heating by an oscillator 5 along with outside heating by a heater 13. The dielectric heating conditions are set so that the product of an oscillating frequency and a square of field strength makes 9.8X10<13>-7.4X10<14> lizV<2>/cm<2>. The speed of the take-off unit 11 is made higher than that of the delivery unit 3 so that the take-off speed per the heating furnace length is 0.3mm.<-1> or less and the take-off speed to delivery speed ratio takes 12 times or more and the rod or pipe is heated and stretched continuously to take the desired elastic modulus 25GPa or more.