US 6,184,317 B2 · Catalysts and processes for the synthesis of alternating ethylene/α-olefin copolymers, and isotactic copolymers thereof

Abstract

Catalysts, catalyst systems and processes for production of alternating copolymers of ethylene and alpha olefins, and to novel classes of atactic and isotactic alternating copolymers of ethylene and alpha olefins, which copolymers include a wide range of crystallinity and exhibit commercially useful properties. Appropriate selection of ligand substituents permit the catalysts to be symmetric or assymetric, resulting in atactic, or isotactic or atactic, respectively, alternatingf copolymers of ethylene with alpha olefins. The novel class of bridged flourenyl metallocene catalysts of the invention is assymetric structural form interconvert between states during polymerization of ethylene with alpha olefins to produce alternating isotactic or atactic copolymers. Exemplary metallocene components of the inventive catalyst systems comprised bridged cyclopentadienly-fluorenyl complexes of the general formula: in which: M is a Group 3, 4 or 5 Transition metal, a Lanthanide or an Actinide; X and X′ are the same or different uninegative ligands; L is a substituted or unsubstituted cyclopentadienyl (Cp) or indenyl ligand; Flu is a substituted or unsubstituted fluorenyl ligand; and Y is a bridging group. When the Cp ligand is symmetric, atactic alternating E/α-olefin copolymers are produced and when the Cp ligand is assymetric, alternating isotactic or atactic E/α-olefin copolymers are produced.

Claims13

Dependent claims

In a method of producing copolymers of ethylene monomer with at least one alpha olefin monomer by reaction of said comonomers in the presence of a catalyst system comprising a metallocene component with a cocatalyst, the improvement which comprises:

a) controlling the stereochemistry of monomer insertion in the polymer chain by carrying out said reaction in the presence of said catalyst system wherein said metallocene is a bridged, asymmetric cyclopentadienyl-fluorenyl complex of the general formula:
in which:
i) M is a Group 3, 4 or 5 Transition metal, a Lanthanide or an Actinide;
ii) X and X′ are the same or different uninegative ligands;
iii) L is at least a mono-substituted cyclopentadienyl (Cp) ring of the formula:
wherein R1 is a substituted or unsubstituted alkyl, alkylsilyl or aryl substitutent of 1 to about 30 carbon atoms and not part of a ring with any one of R2-R4, R2-R4 are the same or different hydrogen or substituted or unsubstituted alkyl, alkylsilyl or aryl substituents from 1 to about 30 carbon atoms;
and any adjacent pair of R2-R4 may be connected in a ring;
iv) Flu is a substituted or unsubstituted fluorenyl ligand;
v) Y is a bridging group;
and
vi) said catalyst assymetry, in the presence of said comonomers, exhibits a first coordination site A in state M, and a second coordination site B in State M′, wherein the kinetic selectivity of each site for the insertion of the comonomers is different;
and
b) said reaction is carried out for a time sufficient to produce copolymers having alternating ethylene/alpha olefin structure in which the copolymers are characterized by an r1r2 of less than about 0.1.

10 more elements

Dependencies are inferred from the claim text.

Catalysts and processes for the synthesis of alternating ethylene/α-olefin copolymers, and isotactic copolymers thereof

Life of this patent

Catalysts and processes for the synthesis of alternating ethylene/α-olefin copolymers, and isotactic copolymers thereof

Life of this patent

Abstract

Claims13