The invention provides a catalyst
system used for preparing ultra-high molecular weight
polyethylene. According to the invention, the catalyst
system comprises active ingredients, outer
electron donors and catalyst promoters; wherein, the total weight of active ingredients of the catalyst based on 100 parts by weight comprises 12.0 to 18.0 parts by weight of
magnesium, 4.0 to 8.0 parts by weight of
titanium, 1.1 to 11.0 parts by weight of
alkoxy group and 55.0 to 75.0 parts by weight of halogens by weight. The method for preparing the active ingredients comprises the steps that:
serous fluid of
magnesium-
alcohol complex is prepared, the
serous fluid reacts with the
electron donor of (R)nSi, pre-loading
titanium reacts with loading
titanium. The ultra-high molecular weight
polyethylene is prepared by adopting the synergistic effect of the active ingredients, R <1> R <11> Si (OR <111>) <2> and the organoaluminium compound R 3-n ALX n of the invention. The catalyst
system of the invention has the advantages of high
bulk density, excellent dynamic stability, and the ultra-high molecular weight
polyethylene prepared has the advantages of good product form, mean particle distribution and high
bulk density; the molecular weight can be adjusted between 2 million and 7 million.