Process for the preparation of a catalytic system, process...

Details Process for the preparation of a catalytic system, process... Process for the preparation of a catalytic system, process...

1998-07-08

2003-04-29

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S128000, C526S127000, C526S129000, C526S153000, C526S161000, C526S336000, C526S351000, C526S352000, C502S120000, C502S155000

Reexamination Certificate

active

06555632

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for the preparation of an ionic catalytic system, starting from a neutral metallocene derived from a transition metal, which is optionally supported, for example on silica, from an organoaluminium compound and from an ionising agent. The invention also relates to a process for the (co)polymerisation of olefins, typically of ethylene and of propylene.
TECHNOLOGY REVIEW
Patent Application EP-426,638 (Fina Technology Inc.) discloses a process for the polymerisation of olefins according to which, in the first stage, the olefin is mixed with an alkylaluminium compound and, in a second stage, a catalyst is added thereto. According to this known process, the catalyst is obtained by mixing an ionising agent such as triphenylcarbenium tetrakis (penta-fluorophenyl) borate with a neutral metallocene derived from a transition metal and selected from cyclopentadiene, indene and fluorene derivatives. Although halogenated metallocenes are mentioned, only nonhalogenated dimethylated metallocenes are explicitly described in the examples.
Nonhalogenated polymethylated metallocenes are generally unstable products obtained by a laborious synthesis. Moreover, it has been observed that catalysts manufactured from nonhalogenated polymethylated metallocenes are particularly unstable and exhibit, during their use for polymerising olefins, an activity which decreases rapidly from the moment of their preparation. This behaviour makes these catalysts difficult to reproduce and consequently inefficient in the polymerisation of olefins.
SUMMARY OF THE INVENTION
The invention overcomes the disadvantages of the known process described above by providing a new process which makes it possible to produce ionic catalytic systems prepared starting from metallocenes (optionally supported), avoiding the use of unstable nonhalogenated polymethylated metallocenes and thus circumventing their laborious synthesis. Another object of the invention is to provide catalytic systems prepared in situ in the polymerisation reactor, thus simplifying the polymerisation process by removing the prior stage for the generation of the ionic metallocene.
DETAILED DESCRIPTION OF THE INVENTION
Consequently the invention relates to a process for the preparation of a catalytic system according to which there is used at least one organoaluminium compound of general formula AlTT′T″, in which T, T′ and T″ each denote a hydrocarbon radical which can optionally comprise oxygen, at least one neutral metallocene derived from a transition metal and at least one ionising agent; according to the invention, the neutral metallocene is selected from compounds of formula (C
p
)
a
(C
p
′)
b
MX
x
Z
z
, in which:
C
p
denotes an unsaturated hydrocarbon radical coordinated to the central atom M
C
p
′ denotes an unsaturated hydrocarbon radical coordinated to the central atom M, or a radical derived from an element chosen from groups VA and VIA of the Periodic Table, the groups C
p
and C
p
′ being identical or different, and being able to be linked via a covalent bridge
M denotes a transition metal chosen from groups IIIB, IVB, VB and VIB of the Periodic Table
a, b, x and z denote integers such that (a+b+x+z)=m, x≧1, z a≧0 and a and/or b≠0
m denotes the valency of the transition metal M
x denotes a halogen
Z denotes a hydrocarbon radical which can optionally comprise oxygen or a silyl radical of formula (—R
t
—Si—R′R″R′″), where
R denotes an optionally substituted alkyl, alkenyl, aryl, alkoxy or cycloalkyl group
R′, R″ and R′″ are identical or different and each denote a halogen or an optionally substituted alkyl, alkenyl, aryl, alkoxy or cycloalkyl group and, in a first stage, a mixture of the organoaluminium compound and of the neutral metallocene in at least one hydrocarbon diluent is prepared and, in a second stage, the ionising agent is added thereto.
In the process according to the invention, the organoaluminium compounds of general formula AlTT′T″ may be chosen from trialkylaluminium compounds such as tributyl-, trimethyl-, triethyl-, tripropyl-, tri-isopropyl-, triisobutyl-, trihexyl-, trioctyl- and tridodecylaluminium. The preferred organoaluminium compounds are those in which the hydrocarbon radicals are chosen from optionally substituted alkyl, alkenyl, aryl and alkoxy groups containing up to 20 carbon atoms. The most advantageous organoaluminium compounds are triethyl aluminium and triisobutylaluminium.
The compounds of formula (C
p
)
a
(C
p
′)
b
MX
x
Z
z
used in the preparation process according to the invention are advantageously those in which the transition metal is selected from scandium, titanium, zirconium, hafnium and vanadium. Zirconium is particularly well suited. The groups C
p
and C
p
′ each advantageously represent an optionally substituted mono- or polycyclic group, comprising from 5 to 50 carbon atoms, linked via conjugated double bonds. There may be mentioned, as a typical example, the cyclopentadienyl, indenyl or fluorenyl radical or a substituted derivative of this radical. The preferred substituted radicals are those in which at least one hydrogen atom is substituted by a hydrocarbon radical comprising up to 10 carbon atoms. It may also be a radical derived from an element chosen from groups VA and VIA of the Periodic Table, for example nitrogen.
In the preparation process according to the invention, the neutral organic derivatives of formula (C
p
)
a
(C
p
′)
b
MX
x
Z
z
, in the case where z is equal to 0, may, for example, be chosen from mono- and dihalogenated metallocenes of scandium, such as chlorodi(cyclopentadienyl) scandium and dichloro (indenyl) scandium, mono-, di- and trihalogenated metallocenes of titanium, such as chlorotri (pentamethylcyclopentadienyl)titanium, dibromo-di (methylcyclopentadienyl)titanium and trichloro(cyclo-pentadienyl)titanium, mono-, di- and trihalogenated metallocenes of zirconium, such as iodotri(cyclopenta-dienyl)zirconium, dibromo(cyclopentadienyl-indenyl)zirconium and trichloro(fluorenyl)zirconium, mono-, di- and trihalogenated metallocenes of hafnium, mono-, di- and trihalogenated metallocenes of vanadium, such as chlorotri (cyclopentadienyl) vanadium, dichlorodi(ethylcyclopentadienyl)vanadium and trichloro(ethylindenyl)vanadium, or mono- and dihalogenated trivalent metallocenes of chromium, such as dichloro(cyclopentadienyl)chromium.
In the case where z is other than 0 and where Z is a hydrocarbon radical, the neutral metallocenes of formula (C
p
)
a
(C
p
′)
b
MX
x
Z
z
may, for example, be chosen from chloro(cyclopentadienyl)ethylscandium, dibromo(methyl-cyclopentadienyl)butyltitanium, chloro(indenyl)isopropyltitanium or dichloro(fluorenyl)hexylzirconium.
In the case where z is other than 0 and where Z is a silyl radical of formula (—R
t
—Si—R′R″R′″), the neutral metallocenes of formula (C
p
)
a
(C
p
′)
b
MXX
x
Z
z
may, for example, be chosen from those comprising, as silyl radical, allyldimethylchlorosilyl, allylmethyldiethoxysilyl, 5-(bicycloheptenyl)trichlorosilyl, 2-bromo-3-trimethylsilyl-1-propenyl, 3-chloropropyldimethylvinylsilyl, 2-(3-cyclohexenyl)ethyltrimethoxysilyl and diphenylvinylchlorosilyl.
The metallocenes having a covalent bridge connecting the two C
p
and C
p
′ groups may be chosen from those of general formula
in which A represents an optionally halogenated alkylene, which can optionally comprise oxygen, alkenylene, arylalkylene, alkylarylene or arylalkenylene group or a radical derived from an element chosen from groups IIIA, IVA, VA and VIA of the Periodic Table, such as boron, aluminium, silicon, germanium, tin, nitrogen, phosphorus and sulphur. There may be mentioned, as examples of bridged metallocenes, those corresponding to the formulae:
in which Ind represents the indenyl radical, Cyc represents the cyclopentadienyl radical, Cyc* represents the pentamethylcyclopentadienyl radical, R and R′ repr

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