高强粗旦聚丙烯工业丝加工条件对其结构及性能的影响

Effect of process conditions on structure and properties of high-strength and coarse-denier polypropylene industrial yarn

以液体冷却成形代替风冷成形,采用两步法生产工艺制得1 980 dtex/60 f高强粗旦聚丙烯工业丝,研究了喷丝头拉伸倍数、液体冷却温度、二级拉伸倍数对其结构及性能的影响。结果表明:从喷丝板挤出的聚丙烯熔体通过液浴骤冷获得的初生单丝含有3个α晶面衍射峰、1个β晶面衍射峰,初生单丝经拉伸作用后,分子中的β晶面消失,结晶度增大;当喷丝头拉伸倍数为3.5、液体冷却温度为30℃、油浴拉伸速度为140 m/min、油浴拉伸倍数为6.5、二级拉伸倍数为2.2时,聚丙烯工业丝的断裂强度最高,为7.42 cN/dtex,力学性能最好,且纺丝较稳定,无长短丝,产品线密度均匀性好。

A high-strength and coarse-denier polypropylene industrial yarn of 1 980 dtex/60 f was prepared by two-step method using liquid quenching formation instead of air quenching formation. The effects of the spinneret draw ratio, liquid quenching temperature and secondary draw ratio on the structure and properties of the industrial yarn were studied. The results showed that the primary monofilament of polypropylene melt extruded from spinneret and exposed to liquid quenching had 3 α-crystal plane diffraction peaks and 1 β-crystal plane diffraction peak, and the β crystal plane disappeared and the crystallinity increased after the primary monofilament was drawn;and the polypropylene industrial yarn had the maximum breaking strength of 7.42 cN/dtex, optimum mechanical properties and favorable linear density uniformity and the spinning process was stable with no long and short yarns formation when the process conditions were optimized as followed: spinneret draw ratio of 3.5, liquid quenching temperature 30 ℃, drawing speed 140 m/min and draw ratio 6.5 in oil bath and secondary draw ratio 2.2.