气相法制备高乙烯含量的高抗冲聚丙烯

Preparation of high impact polypropylene with high ethylene content by gas phase process

反应器内合金化技术生产高抗冲聚丙烯(hi PP)过程中,目前工业上普遍采用加入低纯氮(LPN)的方式阻止聚丙烯颗粒表面生成乙丙橡胶的防粘策略,限制了乙烯含量的提高,使得其抗冲性能受到一定的制约。提出了一种在共聚气相釜中原位添加极少量(<0.1%)超细粉体的方法,通过局载化于聚丙烯颗粒表面,从而起到替代低纯氮的作用,并能通过物理阻隔的方式进一步防止颗粒间发黏聚并,成功将其运用于Hypol工艺,制得高乙烯含量(>20%)且流动性良好的hi PP。同时,将产物与传统低纯氮体系的进行比较,其常温抗冲性能由36.44 k J·m?2升至60.56 k J·m?2,低温抗冲性能由14.78 k J·m?2升至35.12 k J·m?2,体现出其优异的常温和低温抗冲性能。

In the production of high impact polypropylene（hi PP） by in-reactor processes, the ethylene content of hi PP was limited at a low level for the lack of a suitable antisticking method and that by now a deficient antisticking method with low purity nitrogen（LPN） was commonly adopted. A new antisticking method by in-situ adding tiny（0.1%） superfines was adopted in Hypol process to produce hi PP with high ethylene content（20%） and good flowability, showing the possibility to take the place of LPN method. Moreover, the comparison of the product with hi PP prepared by LPN method showed that the anti-impact performance rose from 36.44 k J·m-2 to 60.56 k J·m-2 at 23℃ and from 14.78 k J·m-2 to 35.12 k J·m-2 at -20℃, respectively. It was found that hi PP with high ethylene content presented excellent anti-impact performance at both 23℃ and -20℃.