Supported metallocene-alumoxane catalysts for the preparation of polyethylene having a broad monomodal molecular weight distribution

• US 5,914,289 A
• Filed: 02/07/1997
• Issued: 06/22/1999
• Est. Priority Date: 02/19/1996
• Status: Expired due to Fees

• Current Assignee: FINA Research SA
• Original Assignee: FINA Research SA
• Inventors: Razavi, Abbas
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): PASTERCZYK, JAMES W
• Application Number:
  US08/797,800
• Time in Patent Office: 865 Days
• Field of Search: 502/103, 502/117, 502/132, 502/107
• US Class Current: 502/107
• CPC Class Codes: C08F 10/00 Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
• CPC Class Codes: C08F 210/14 Monomers containing five or more carbon atoms
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 2500/04 Broad molecular weight distribution, i.e. Mw/Mn > 6
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 2500/18 Bulk density
• CPC Class Codes: C08F 4/65912 in combination with an organoaluminium compound
• CPC Class Codes: C08F 4/65916 supported on a carrier, e.g. silica, MgCl2, polymer
• CPC Class Codes: C08F 4/65927 two cyclopentadienyl rings being mutually bridged
• CPC Class Codes: Y02P 20/52 using catalysts, e.g. selective catalysts
• CPC Class Codes: Y10S 526/934 Electrodeposit, e.g. electrophoretic, xerographic
• CPC Class Codes: Y10S 526/943 Polymerization with metallocene catalysts

Abstract

The present invention relates to the production of high density polyethylene homopolymers or copolymers having a broad and monomodal molecular weight distribution wherein the polymerization process is conducted in the presence of supported metallocene-alumoxane catalysts wherein the metallocene is bridged, comprises at least a hydrogenated indenyl or fluorenyl and a metal M which may be Ti, Zr or Hf, wherein a plurality of conformers of the metallocene are formed and isolated on the support by reaction of the metallocene with the alumoxane and depositing the product formed on the support at a temperature in the range 85° C. to 110° C.

Claims

1. A catalyst system comprising a metallocene-alumoxane catalyst for use in the preparation of polyolefins having a broad monomodal molecular weight distribution and a support for supporting the catalyst, wherein the metallocene comprises at least one hydrogenated indenyl or fluorenyl, a metal, and a bridge between (a) said at least one hydrogenated indenyl or fluorenyl and (b) another hydrogenated or non-hydrogenated indenyl or fluorenyl;

and wherein a plurality of conformers of the metallocene are formed and isolated on the support by reaction of the metallocene with the alumoxane and depositing the product formed on the support at a temperature in the range of 85°

C. t 110°

C.

2. A catalyst system according to claim 1 further comprising a cocatalyst represented by the formula AlR₃, wherein each R is the same or different and is selected from the group consisting of halides and alkyl groups having from 1 to 12 carbon atoms.

3. A catalyst system according to claim 2 wherein the cocatalyst is trialkylaluminum selected from the group consisting of trimethylaluminum, triethylaluminum and triisobutylaluminum.

4. A catalyst system according to claim 1 wherein the bridged metallocene is selected from hydrogenated bisindenyl compounds having the following formula:

space="preserve" listing-type="equation">(IndH.sub.4).sub.2 R"MQ.sub.2

wherein Ind is an indenyl or a substituted indenyl, R'"'"' is a C₁ -C₄ alkylene radical, a dialkyl germanium or silicon or siloxane, or an alkyl phosphinidine or imido group bridging the indenyls, each Q is a hydrocarbyl radical, a hydrocarboxy radical having 1-20 carbon atoms or halogen and can be the same or different from each other, and M is Ti, Zr or Hf.

5. A catalyst system according to claim 4 wherein the metallocene is ethylenebis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride.

6. A catalyst system according to claim 1 wherein the metallocene comprises either only its racemic stereoisomers or only its meso stereoisomer.

7. A catalyst system according to claim 6 wherein the metallocene comprises only its racemic stereoisomers.

8. A catalyst system according to claim 4, wherein each Q is independently selected from the group consisting of aryl, alkyl alkenyl, alkylaryl and aryl radicals having 1-20 carbon atoms.

9. A catalyst system according to claim 3, wherein the trialkylaluminum is triisobutylaluminum.