Molecular weight distribution modification in a tubular reactor
First Claim
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1. A method for preparing a polymodal MWD ethylene copolymer which comprises:
- (a) conducting the polymerization in a substantially mix free reactor;
(b) using at least two catalyst species each of which initiates a polymer chain of a different molecular weight than the other catalyst species;
(c) using at least one reaction mixture comprising ethylene and at least one alpha-olefin monomer, said reaction mixture being essentially transfer-agent free;
(d) in such a manner and under such conditions sufficient to initiate propagation of essentially all copolymer chains simultaneously;
the resulting polymer comprising at least two modes of differing molecular weights, each mode having at least one of Mw /Mn of less than 2 and Mz /Mw of less than 1.8, the resulting polymer being a polymodal MWD ethylene copolymer.
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Abstract
Polymodal MWD ethylene copolymer comprising at least two modes of differing molecular weights. Each mode has at least one of Mw /Mn of less than 2.0, and a Mz /Mw of less than 1.8. The polymodal character of the copolymer is achieved by either (1) withdrawing polymer modes from the reactor from at least one takeoff port, and blending such modes with the reactor effluent, or (2) utilizing at least two catalyst species in the reaction to produce modes of differing molecular weights.
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Citations
25 Claims
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1. A method for preparing a polymodal MWD ethylene copolymer which comprises:
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(a) conducting the polymerization in a substantially mix free reactor; (b) using at least two catalyst species each of which initiates a polymer chain of a different molecular weight than the other catalyst species; (c) using at least one reaction mixture comprising ethylene and at least one alpha-olefin monomer, said reaction mixture being essentially transfer-agent free; (d) in such a manner and under such conditions sufficient to initiate propagation of essentially all copolymer chains simultaneously;
the resulting polymer comprising at least two modes of differing molecular weights, each mode having at least one of Mw /Mn of less than 2 and Mz /Mw of less than 1.8, the resulting polymer being a polymodal MWD ethylene copolymer. - View Dependent Claims (2, 3, 5, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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4. hydrocarbon-soluble complexes with VCl3 ;
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(b) organo-aluminum compound selected from the group consisting of;
space="preserve" listing-type="equation">AlR.sub.3
space="preserve" listing-type="equation">AlR.sub.2 Cl,
space="preserve" listing-type="equation">Al.sub.2 R.sub.3 Cl.sub.3,
space="preserve" listing-type="equation">AlRCl.sub.2,
space="preserve" listing-type="equation">AlR'"'"'RCl,
space="preserve" listing-type="equation">Al(OR'"'"')R.sub.2,
space="preserve" listing-type="equation">R.sub.2 Al-OAlR.sub.2, and
space="preserve" listing-type="equation">AlR.sub.2 I,where R and R'"'"' are hydrocarbon radicals. - View Dependent Claims (6, 8)
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Specification