Catalyst system for the production of ultra-high molecular weight polyethylene

A catalyst system comprising:

• I. a solid reaction product obtained by reaction of:
• (a) a hydrocarbon solution comprising
• (1) an organic oxygen containing magnesium compound or a halogen containing magnesium compound and
• (2) an organic oxygen containing titanium compound
• (b) a mixture comprising a metal compound having the formula MeRnX3-n wherein X is a halogenide, Me is a metal of Group III of Mendeleev's Periodic System of Chemical Elements, R is a hydrocarbon radical containing 1-10 carbon atoms and 0≦n≦3 and a silicon compound of formula RmSiCl4-m wherein 0≦m≦2 and R is a hydrocarbon radical containing 1-10 carbon atoms wherein the molar ratio of metal from (b):
• titanium from (a) is lower than 1:1 and
• (c) post treatment of the obtained solid reaction product with an aluminium compound having the formula AlRnCl3-n wherein R is a hydrocarbon radical containing 1-10 carbon atoms and 0<n≦3
• II. an organo aluminium compound having the formula AlR3 in which R is a hydrocarbon radical containing 1-10 carbon atoms and
• III. an electron donor selected from the group of 1,2-dialkoxyalkanes, 1,2-dialkoxyalkenes and a polymeric electron donor.

A process for preparing a catalyst system for the production of ultra-high molecular weight polyethylene comprising

• I. reacting:
• (a) a hydrocarbon solution comprising
• (1) an organic oxygen containing magnesium compound or a halogen containing magnesium compound and
• (2) an organic oxygen containing titanium compound and
• (b) a mixture comprising a metal compound having the formula MeRnX3-n in which X is a halogenide, Me is a metal of Group III of Mendeleev's Periodic System of Chemical Elements, R is a hydrocarbon radical containing 1-10 carbon atoms and 0≦n≦3 and a silicon compound of formula RmSiCl4-m wherein 0≦m≦2 and R is a hydrocarbon radical containing 1-10 carbon atoms wherein the molar ratio of metal from I (b):
• titanium from I (a)(2) i is lower than 1:1 and optionally
• (c) post treatment of the obtained solid reaction product with an aluminium compound having the formula AlRnCl3-n wherein R is a hydrocarbon radical containing 1-10 carbon atoms and 0<n≦3
• and combining the reaction product from (I) with
• II. an organo aluminium compound having the formula AlR3 in which R is a hydrocarbon radical containing 1-10 carbon atoms
• wherein an electron donor selected from the group of 1,2-dialkoxyalkanes, 1,2-dialkoxyalkenes and a polymeric electron donor is added separately from the organo aluminium compound(II) and is premixed for less than 30 minutes with the solid reaction product from (I).

A process for the production of ultra-high molecular weight polyethylene, comprising:

• polymerizing in the presence of a catalyst system comprising
• I. a solid reaction product obtained by reaction of:
• (a) a hydrocarbon solution comprising
• (1) an organic oxygen containing magnesium compound or a halogen containing magnesium compound and
• (2) an organic oxygen containing titanium compound and
• (b) a mixture comprising a metal compound having the formula MeRnX3-n wherein X is a halogenide, Me is a metal of Group III of Mendeleev's Periodic System of Chemical Elements, R is a hydrocarbon radical containing 1-10 carbon atoms and 0≦n≦3 and a silicon compound of formula RmSiCl4-m wherein 0≦m≦2 and R is a hydrocarbon radical containing 1-10 carbon atoms wherein the molar ratio of metal from I (b):
• titanium from I (a)(2) is lower than 1:1
• II. an organo aluminium compound having the formula AlR3 in which R is a hydrocarbon radical containing 1-10 carbon atoms
• wherein an electron donor is added during the polymerisation.