Patent ID: 9447206
Filing Date: 2016-09-20
CPC Classification: C08F

Claim Text:
1. A process for the preparation of ethylene polymers comprising: introducing ethylene, a diluent, a catalyst, a co-catalyst and optionally comonomers and hydrogen into a first loop reactor to form a first reaction mixture, polymerizing ethylene and optionally comonomers in the first reaction mixture to form ethylene polymers, discharging the first reaction mixture from the first loop reactor, introducing the first reaction mixture and fresh ethylene and optionally comonomers and hydrogen into one or more second reactors to form additional ethylene polymers within a second reaction mixture, wherein the polymerization in all reactors is performed under slurry conditions, and wherein the one or more second reactors are arranged in series and downstream from the first loop reactor and wherein one or more second reactors comprise loop reactors; discharging the second reaction mixture from the one or more second reactors; and recovering ethylene polymer, wherein additional co-catalyst is injected in at least one of the second reactors such that the concentration of co-catalyst injected in the at least one of the second reactors, and based on the fresh diluent injected in the at least one of the second reactors, is between 0.1 X and X, wherein X is the concentration of co-catalyst injected in the first loop reactor based on the fresh diluent injected in the first loop reactor, and the production capacity of each reactor is essentially unchanged from a process wherein additional co-catalyst is not injected in at least one of the second reactors; wherein catalyst is injected only into the first loop reactor, and wherein the catalyst is a metallocene catalyst or a chromium catalysts.