Bimodal polyethylene

摘要

The invention relates to A process for the polymerization of ethylene to produce a polyethylene resin in at least two slurry loop reactors connected to each other in series, the resin having a bimodal molecular weight distribution, a molecular weight distribution MWD of at least 7.0, an HLMI of from 1 to 100 g/10 min, and a density of from 0.935 to 0.960 g/cm3,
wherein in one reactor 30 to 47 wt % based on the total weight of the polyethylene resin of a high molecular weight (HMW) polyethylene fraction is produced having an HL275 of from 0.05 to 1.8 g/10 min (the equivalent of HLMI of from 0.01 to 1.56 g/10 min), a density of from 0.925 to 0.942 g/cm3 and an MWD of at least 5.0,and in the other reactor a low molecular weight (LMW) polyethylene fraction is produced having an HLMI of from 10 to 1500 g/10 min and a density of from 0.960 to 0.975 g/cm3,in the presence of a Ziegler-Natta catalyst system.

主权项

1. A bimodal polyethylene resin comprising:
30 to 47 wt % of a high molecular weight (HMW) polyethylene fraction based on a total weight of the polyethylene resin, wherein the HMW polyethylene fraction has an HL275 of from 0.05 to 1.8 g/10 min (HLMI=HL275÷3.2), a density of from 0.925 to 0.942 g/cm3 and an MWD of at least 5.0; and a low molecular weight (LMW) polyethylene fraction having an HLMI of from 10 to 1500 g/10 min and a density of from 0.960 to 0.975 g/cm3; wherein the bimodal polyethylene resin has a molecular weight distribution MWD of at least 7.0, an HLMI of from 1 to 100 g/10 min, and a density of from 0.935 to 0.960 g/cm3; wherein density is measured according to ASTM 1505 at a temperature of 23° C., wherein the HLMI is measured according to ASTM D 1238 at a temperature of 190° C. and under a load of 21.6 kg, and wherein the HL275 is measured according to the measurement of HLMI in ASTM D 1238 at a temperature of 190° C. and under a load of 21.6 kg, except that a die of 2.75 mm broad is used.