固相增黏PET切片色相b值的影响因素探讨

Influential factors on hue b value of solid-state polycondensed PET chip

以精对苯二甲酸、乙二醇及第三单体为原料,在100 kt/a聚对苯二甲酸乙二醇酯(PET)五釜工艺流程上生产基础PET切片,再经固相缩聚增黏工艺生产增黏PET切片;针对常用的瓶用及太阳能背板膜专用增黏PET切片,根据装置实际运行状况讨论了增黏PET切片色相b值的影响因素。结果表明:基础PET切片b值、固相增黏反应工艺条件是增黏PET切片b值的主要影响因素,原料质量及第三单体、催化剂、调色剂等加入量对增黏PET切片b值也有一定的影响;增黏PET切片b值与基础PET切片b值之间存在着线性关系,加强监控基础PET切片b值可提前预控增黏PET切片成品的b值;在固相缩聚过程中,合理控制固相缩聚反应温度、停留时间(反应器液位)、冷却温度(氮气流量),可使增黏PET切片产品b值达到控制指标要求。

Using purified terephthalic acid,ethylene glycol and third monomer as raw materials,basic polyethylene terephthalate(PET)chips were produced on a 100 kt/a PET production plant of five-reactor process,and then polycondensed PET chips were produced by solid-state polycondensation process.Based on the actual operating conditions of the plant,the influential factors on the hue b value of the polycondensed PET chips were discussed for the common PET chips for bottle flakes and solar backplane film.The results showed that the main influential factors on the b value of polycondensed PET chips included the b value of basic PET chips and the process conditions of solid-state polycondensation,and the quality of raw materials and the addition amounts of third monomer,catalyst and toner also had a certain influence on the b value of the polycondensed PET chips;there was a linear relationship between the b values of the polycondensed and basic PET chips,and the b value of the polycondensed PET chips could be controlled in advance by enhancing the monitoring of the b value of the basic PET chips;and the reasonable control of solid-state polycondensation reaction temperature,residence time(reactor liquid level)and cooling temperature(nitrogen flow rate)in the process of solid-state polycondensation can make the b value of the polycondensed PET chips meet the control index requirements.