PURPOSE: To obtain the title fiber with both high mechanical strength and modulus, excellent in thermal dimensional stability etc., thus suitable for tire cords, transmission belts, etc., by delayed cooling of a specific polymer followed by drawing in a plasma atmosphere.
CONSTITUTION: A polymer with ≥90mol% of the total recurring units in the molecular chain representing polyethylene terephthalate and an intrinsic viscosity of ≥0.7 is put to melt spinning followed by delayed cooling through a high temperature atmospheric zone at pref. 200-350°C just under a spinneret and then solidification, in a cooling zone ≥100mm in length, by spraying a gas at pref. ≥120°C at a velocity of 15-50m/min and then winding on a take-up roller at a speed of ≥1500m/min, thus producing a medium-oriented fiber. This fiber is then drawn by a factor of 1.4-3.5 under a tension of 1.0-5.0g/de in a plasma atmosphere, thus obtaining the objective fiber.
YOSHINO MASATO
OGURA AKIRA
