| 摘要 |
PURPOSE:A polyester yarn whose intrinsic viscosity, strength, elongation, optical birefringence and density are in a specific range, individually, thus being used as a base fabric for extensible adhesive tapes, because it is low in strength and high in elongation. CONSTITUTION:The objective polyester yarn has an intrinsic viscosity over 0.6, a strength of 1.5-3g/d, an elongation of 30-80%, an optical birefringence of 0.11-0.17 and a density of 1.38-1. 39. The yarn is reaidily produced by melt-extruding a polyester at a taking-up speed of 2,500-4,000m/min into an undrawn yarn with an intrinsic viscosity of over 0.6. The undrawn yarn is drawn at a ratio of over 1.05 and heat-set at 180-230 deg.C under a tension less than the natural draw ratio.
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