高堆积密度超高分子量聚乙烯的制备

Preparation of High Bulk density Ultra high Molecular Weight Polyethylene

研究了制备超高分子量聚乙烯的Ｚｉｅｇｌｅｒ－Ｎａｔａ型催化剂的组成，考察了催化剂中第三组份对聚合反应活性、聚合物粘均分子量，以及粉体堆积密度的影响。用所制备的催化体系在１０Ｌ聚合釜中进行了乙烯的淤浆聚合反应，聚合活性大于３００ｋｇ（ＰＥ）／ｇ（Ｔｉ），聚合物粘均分子量在４×１０６以上，粉体堆积密度超过０．３７ｇ／ｃｍ３。用扫描电子显微镜观察了含不同第三组份的催化剂颗粒及对应的聚乙烯颗粒的微观结构，认为含第三组份Ｂ的催化剂颗粒比表面大，聚合活性高，生成的聚乙烯颗粒结构紧密呈丝网状，其聚合物粉体的堆积密度较高。本研究摸索的最佳工艺条件为：聚合温度：６０～６５℃，聚合压力为０．３～０．４ＭＰａ，搅拌速度２５０ｒ／ｍｉｎ。

s The composition of Zieglar Natta type catalyst used in the synthesis of ultra high molecular weight polyethylene (UHMWPE) was studied,and the effect of the 3rd composition in the catalyst on the polymerization yield,viscometric average molecular weight (VAMW) and bulk density (BD) of the polymer powder was also investigated.The slurry polymerization process was carried out in a 10-litre reactor,initiated by the prepared catalyst,with a polymerization yield over 300 kg(PE)/g (Ti),the VAMW and BD of the obtained polymer were over 4 million and 0.37g/cm respectively.By means of SEM,the morphologies of the catalyst particles with different 3rd components and the morphology of the PE particles were compared.The catalyst paticles with 3rd components (B) had great specific surface and high polymerization yield,and the prepared PE had a dense and silk like network structure,with a great bulk density.The optimum technical conditions obtained in this work were as follows: polymerization temperature 60℃～65℃;Pdlymerixation Pressure 0.3～0.4 MP,agitation speed 250r/mim.