catalyst

Abstract

A catalyst in solid particulate form free from an external carrier material comprising

• • (i) a complex of formula (I)

• • wherein
  • M is zirconium or hafnium;
  • each X is a sigma ligand;
  • L is a divalent bridge selected from —R′₂C—, —R′₂C—CR′₂—, —R′₂Si—, —R′₂Si—SiR′₂—, —R′₂Ge—, wherein each R′ is independently a hydrogen atom, C_1-20-alkyl, tri(C_1-20-alkyl)silyl, C_6-20-aryl, C_7-20-arylalkyl or C_7-20-alkylaryl;
  • R₂ is a C_1-20-hydrocarbyl radical;
  • R_2′ is a C_1-20-hydrocarbyl radical;
  • R₆ is a linear or branched aliphatic C_1-20-hydrocarbyl group, SR₉ or OR₉;
  • R_6′ is a linear or branched aliphatic C_1-20-hydrocarbyl group, SR_9′ or OR_9′;
  • with the proviso that neither R₆ or R_6′ represents a group having a quaternary carbon atom directly attached to the indenyl ring;
  • R₉ is a C_1-20-hydrocarbyl group;
  • R_9′ is a C_1-20-hydrocarbyl group;
  • Ar is a C_6-12-aryl or C_5-12-heteroaryl group optionally carrying one or more substituents R₈;
  • Ar′ is a C_6-12-aryl or C_5-12-heteroaryl group optionally carrying one or more substituents R_8′;
  • each R₈ is a C_1-20-hydrocarbyl group;
  • each R_8′ is a C_1-20-hydrocarbyl group; and
  • wherein at least two of R₂ and R_2′; R₆ and R_6′; or Ar and Ar′ are the same;
  • and (ii) a cocatalyst comprising a compound of a group 13 metal, e.g. Al or boron.

Description

FIELD OF INVENTION[0001]This invention relates to new bisindenyl catalysts, in particular, solid particulate racemic symmetrical metallocene catalysts containing such bisindenyl ligands. The invention also relates to the use of such new bisindenyl metallocene catalysts for the production of polypropylene at excellent catalyst activities to give polypropylene with high molecular weight, and high melting point even at industrially relevant polymerization temperatures.BACKGROUND OF INVENTION[0002]Metallocene catalysts have been used to manufacture polyolefins for many years. Countless academic and patent publications describe the use of these catalysts in olefin polymerisation. Metallocenes are now used industrially and polyethylenes and polypropylenes in particular are often produced using cyclopentadienyl based catalyst systems with different substitution patterns.[0003]The two most important physical properties of isotactic polypropylene (iPP) are its average molecular weight and it...

AI Technical Summary

Problems solved by technology

When the polymerization temperature is increased to 30° C., the melting point of the resulting polypropylene decreases to 158° C. A polymerization temperature of −30° C. is however, far too low for polypropylene manufacturing in commercial plants, which need to be operated above 60° C. When used at industrially useful polymerization

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