冷凝态下高MFR HDPE注塑专用树脂开发中的问题分析

分析了在气相流化床工艺高负荷冷凝态下开发生产高熔体流动速率(MFR)高密度聚乙烯树脂存在的问题。当氢气摩尔分数超过18%以后,树脂平均粒径大幅下降,聚合反应循环系统细粉的浓度大幅增加,易造成夹带,循环过程中在反应器扩大段部分易沉降粘壁,堵塞反应换热器和分布板。抑制细粉的产生主要采取选择催化剂、控制催化剂活性、控制反应温度等措施。

Problem analysis of development of special HDPE resin with high MFR for injection molding in condensation state

The authors analyzed the problems occurred in the development and production of high density polyethylene(HDPE) resin with high melt flow rate(MFR) in condition of high load and condensation state in Univation gas fluidized bed process.When the molar concentration of hydrogen exceeded 18%,the average particle size of the resin powder declined significantly.In the circulatory system of polymerization,the concentration of fine powder dramatically increased,which easily caused entrainment and therefore,formed settlement and fouling in the expand segment part of the reactor in the cycle process.As a consequence,the heat exchanger and distribution board of the reactor were blocked up.The main countermeasures for suppressing generation of the fine powder involved adoption of proper catalyst,control of catalyst′s activity,adjustment of reaction temperature,etc.