EP0905153A1
Expired / Lapsed
EP
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Production of polyethylene having a broad molecular weight distribution
Assignee: Total Petrochemicals Research Feluy SA
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Filing: 1998-09-25
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Granted: —
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Expires: 2018-09-25
Abstract
Abstract A process for producing high density polyethylene in the presence of a Ziegler-Natta catalyst system in two liquid full loop reactors in series, wherein in a first reactor a first polyethylene product is polymerised substantially by homopolymerisation of ethylene and hydrogen, optionally with a minor degree of copolymerisation of ethylene with an alpha-olefinic comonomer comprising from 3 to 8 carbon atoms, and in a second reactor serially connected to the first reactor downstream thereof a second polyethylene product is copolymerised from ethylene and an alpha-olefinic comonomer comprising from 3 to 8 carbon atoms, and a hydrogenation catalyst is introduced into the reactants downstream of the first reactor.
Inventors
- 👤 Guy Debras
- 👤 Michel Messiaen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 08:11
CPC Classifications
C; C08; C08F; C08F297/00; C08F297/06; C08F297/08; C08F297/083; C08F210/00; C08F210/04; C08F210/06; C08F210/16
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
107 words
A process for producing high density polyethylene in the
presence of a Ziegler-Natta catalyst system in two liquid full
loop reactors in series, wherein in a first reactor a first
polyethylene product is polymerised substantially by
homopolymerisation of ethylene and hydrogen, optionally with a
minor degree of copolymerisation of ethylene with an alpha-olefinic
comonomer comprising from 3 to 8 carbon atoms, and in
a second reactor serially connected to the first reactor
downstream thereof a second polyethylene product is copolymerised
from ethylene and an alpha-olefinic comonomer comprising from 3
to 8 carbon atoms, and a hydrogenation catalyst is introduced
into the reactants downstream of the first reactor.
Claim 2
Dependent Claim
25 words
A process according to claim 1 wherein the hydrogenation
catalyst is introduced into the process stream passing from the
first reactor to the second reactor.
Claim 3
Dependent Claim
74 words
A process according to claim 1 or claim 2 wherein the
hydrogenation catalyst comprises a metallocene catalyst of
general formula: Cp 2 MX n where Cp is a substituted or unsubstituted cyclopentene dienyl
group; M is a transition metal from Group IVB of the Periodic
Table or vanadium; X is a halogen or a hydrocarbyl group having
from 1 to 10 carbon atoms; and n is the valency of the metal M
minus 2.
Claim 4
Dependent Claim
25 words
A process according to claim 3 wherein the metallocene
catalyst comprises Cp 2 TiCl 2 wherein Cp is a substituted or
unsubstituted cyclopentene dienyl group.
Claim 5
Dependent Claim
34 words
A process according to any foregoing claim wherein the
degree of copolymerisation in the first reactor is limited to an
amount whereby the first polyethylene product has a density of
not less than 0.960g/cc.
Claim 6
Dependent Claim
12 words
A process according to any foregoing claim wherein the
comonomer comprises 1-hexene.
Claim 7
Dependent Claim
54 words
A process according to any foregoing claim wherein the
homopolymerisation and copolymerisation processes are carried out
at a temperature of from 60 to 110°C, under an absolute pressure
of 1 to 100 bar, and the homopolymerisation in the first reactor
is carried out at a higher temperature than the copolymerisation
in the second reactor.
Claim 8
Dependent Claim
48 words
A process according to any foregoing claim wherein in the
first reactor, the ethylene monomer comprises from 0.1 to 3% by
weight based on the total weight of the ethylene monomer in an
inert diluent and the hydrogen comprises from 0.1 to 2 mol% on
the same basis.
Claim 9
Dependent Claim
39 words
A process according to any foregoing claim wherein the low
molecular weight polyethylene fraction produced in the first
reactor comprises from 30 to 70% by weight of the total
polyethylene produced in the first and second serially connected
reactors.
Claim 10
Dependent Claim
47 words
A process according to any foregoing claim wherein in the
second reactor the ethylene monomer comprises from 0.1 to 2% by
weight, and the comonomer comprises from 1 to 3% by weight, each
based on the total weight of the monomer and comonomer in an
inert diluent.
References Cited (Backward Citations)
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