Claims
- 1. A process for preparing bimodal molecular weight distribution copolymers of ethylene with alpha-olefins having from 3 to 20 carbon atoms, said copolymers having:(a) a comonomer distribution wherein the comonomer level at the mid-position of the low molecular weight component is less than or equal to 1.6 times the level at the mid-position of the high molecular weight component, and (b) a total average comonomer content in the range from 0.5 to 20 short chain branches (SCB)/1000 carbon atoms wherein said process is carried out in the presence of a supported multisite catalyst, wherein all the catalyst components are supported on a single support, said catalyst comprising a Ziegler catalyst component and a metallocene component having any of the formulae:(C5R5)(C5R15)MY2 (I) (C5R2H3)(C5R12H3)MY2 (II) (C5R4)Z(C5R14)MY2; (III) or(C5RmH5−m)(C5R1nR5−n)MY2 (IV) wherein:C5R5 and C5R15 represent a cyclopentadienyl ligand, R and R1 are alkyl, aryl, alkylaryl, alkenyl, or haloalkyl groups and may be the same or different, Z is a bridging group selected from the group consisting of CX2, SiX2, and GeX2, X is hydrogen or a group as defined by R and R1, M is Zr, Ti, or Hf, Y is a univalent anionic ligand and wherein in Formula (II) at least one of R and R1 has ≧three carbon atoms, and in Formula (IV) m is 3 or 4 and n is 5 or less.
- 2. A process according to claim 1 wherein the total average comonomer content is in the range from 1 to 20 short chain branches (SCB)/1000 C atoms.
- 3. A process according to claim 1 wherein the multisite catalyst is supported on silica, alumina or magnesium chloride.
- 4. A process according to claim 1 wherein M is zirconium.
- 5. A process according to claim 1 wherein the metallocene component is bis(pentamethylcyclopentadienyl) zirconium dichloride or bis(1-propenyl-2-methylcyclopentadienyl) zirconium dichloride.
- 6. A process according to claim 1 wherein the multisite catalyst is used in the presence of at least one co-catalyst.
- 7. A process according to claim 6 wherein the co-catalyst is an organo aluminium compound.
- 8. A process according to claim 7 wherein the organo aluminium compound is methyl aluminoxane or trimethyl aluminium.
- 9. A process according to claim 1 carried out in the gas phase.
- 10. A process as defined in claim 1 wherein Y is a halide or an alkyl or an alkoxy group.
- 11. A process as defined in claim 1 wherein the bridging group Z is CX2, SiX2, or GeX2 and Y is a halide or an alkyl or an alkoxy group.
Priority Claims (2)
Number |
Date |
Country |
Kind |
9406855 |
Apr 1994 |
GB |
|
9417364 |
Aug 1994 |
GB |
|
Parent Case Info
This application is a continuation, of application Ser. No. 08/657,534, filed Jun. 5, 1996, now abandoned, which is a continuation, of application Ser. No. 08/410,984, filed Mar. 27, 1995, now abandoned.
US Referenced Citations (5)
Number |
Name |
Date |
Kind |
5032562 |
Lo et al. |
Jul 1991 |
A |
5124418 |
Welborn, Jr. |
Jun 1992 |
A |
5145818 |
Tsutsui et al. |
Sep 1992 |
A |
5332706 |
Nowlin et al. |
Jul 1994 |
A |
5395810 |
Shamshoum et al. |
Mar 1995 |
A |
Continuations (2)
|
Number |
Date |
Country |
Parent |
08/657534 |
Jun 1996 |
US |
Child |
08/904236 |
|
US |
Parent |
08/410984 |
Mar 1995 |
US |
Child |
08/657534 |
|
US |