Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1997-06-05
2001-01-23
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...
C526S129000, C526S160000, C526S348000, C526S943000, C502S104000, C502S120000, C502S121000, C502S122000, C502S123000
Reexamination Certificate
active
06177526
ABSTRACT:
The present invention relates to a highly active supported catalyst system which can advantageously be used in olefin polymerization and a process for its preparation as well as polymers which are prepared using the supported catalyst system.
Processes are known for preparing polyolefins with the aid of soluble, homogeneous catalyst systems comprising a transition metal component of the metallocene type and a cocatalyst component of the aluminoxane type, a Lewis acid or an ionic compound. These catalysts have a high activity and give polymers and copolymers having a narrow molecular weight distribution.
In polymerization processes using soluble, homogeneous catalyst systems, thick deposits form on reactor walls and stirrer if the polymer is obtained as a solid. These deposits are formed by agglomeration of the polymer particles whenever metallocene and/or cocatalysts are present in dissolved form in the suspension. Such deposits in the reactor systems have to be removed regularly, since they quickly reach considerable thicknesses, have a high strength and prevent heat exchange to the cooling medium. Furthermore, homogeneous catalyst systems cannot be used for the preparation of polyolefins in the gas phase. To avoid deposit formation in the reactor, supported catalyst systems in which the metallocene and/or the aluminum compounds serving as cocatalyst are fixed on an inorganic support material have been proposed.
EP-A-576970 discloses a catalyst system comprising a metallocene of the formula
where
M
a
is a metal of group IVb, Vb or VIb of the Periodic Table, R
a
and R
b
are identical or different and are each a hydrogen atom, a C
1
-C
10
-alkyl group, a C
1
-C
10
-alkoxy group, a C
6
-C
10
-aryl group, a C
6
-C
10
-aryloxy group, a C
2
-C
10
-alkenyl group, a C
7
-C
40
-arylalkyl group, a C
7
-C
40
-alkylaryl group, a C
8
-C
40
-arylalkenyl group, an OH group or a halogen atom, the radicals R
c
are identical or different and are each a hydrogen atom, a halogen atom, a C
1
-C
10
-alkyl group which may be halogenated, a C
6
-C
10
-aryl group, an —NR
p
2
, —SR
p
, —OSiR
p
3
—, —SiR
p
3
— or —Pr
p
2
radical, where R
p
is a halogen atom, a C
1
-C
10
-alkyl group or a C
6
-C
10
-aryl group, R
d
to R
l
are identical or different and are as defined for R
c
, or adjacent radicals R
d
to R
l
together with the atoms connecting them form one or more aromatic or aliphatic rings, or the radicals R
e
and R
h
or R
l
together with the atoms connecting them form an aromatic or aliphatic ring, R
m
is
where R
n
and R
o
are identical or different and are each a hydrogen atom, a halogen atom, a C
1
-C
10
-alkyl group, a C
1
-C
10
-fluoroalkyl group, a C
1
-C
10
-alkoxy group, a C
6
-C
10
aryl-group, a C
6
-C
10
-fluoroaryl group, a C
6
-C
10
-aryloxy group, a C
2
-C
10
-alkenyl group, a C
7
-C
40
-arylalkyl group, a C
7
-C
40
-alkylaryl group, a C
8
-C
40
-arylalkenyl group, or R
n
and R
o
in each case together with the atoms connecting them form one or more rings and M
b
is silicon, germanium or tin, and a supported cocatalyst. This supported catalyst system gives isotactic polypropylene at an activity of from 50 to 540 kg of PP/g of metallocene xh at an Al:Zr ratio of >400:1.
EP-A-287666 describes a process for the polymerization of olefins in the presence of a catalyst comprising a transition metal compound, an aluminoxane, an organoaluminum compound having a hydrocarbon group different from n-alkyl groups and an inorganic support which may be modified by an organometallic compound or a halogen-containing silicon compound as solid catalyst component, where the transition metal compound is represented by the formula
R
q
k
R
r
l
R
s
m
R
t
n
Me,
where R
q
is a cycloalkadienyl group, R
r
, R
s
and R
t
are identical or different and are each a cycloalkadienyl group, an aryl group, an alkyl group, an arylalkyl group, a halogen atom or a hydrogen atom, Me is zirconium, titanium or hafnium, k is 1, 2, 3 or 4, l, m and n are 0, 1, 2 or 3 and k+l+m+n=4. The halogen-containing silicon compounds used for modifying the inorganic support are represented by the formula
SiY
d
R
u
e
(OR
v
)
4-d-e
where Y is a chlorine or bromine atom, R
u
and R
v
are, independently of one another, each an alkyl group having from 1 to 12 carbon atoms, an aryl or cycloalkyl group having from 3 to 12 carbon atoms, d is from 1 to 4 and e is from 0 to 4 and d+e is from 1 to 4. This process gives polymers in good yields.
EP-A-206794 mentions, for example, SiCl
4
, chlorosilanes such as trimethylchlorosilane or dimethylaminotrimethylsilane for the chemical modification of the hydroxyl groups on a support surface. A good polymerization activity is obtained.
EP-A-553491 discloses a catalyst for the polymerization of olefins which comprises a supported transition metal compound having a carbon-bridged biscyclopentadienyl-like ligand system and an aluminoxane. The inorganic support component used is modified with an organic or inorganic compound in order to reduce the content of hydroxyl groups on the surface. This is done using, for example, organoaluminum, organomagnesium or organosilicon compounds such as trimethylsilane or dimethyldichlorosilane. Polymers are obtained in good yields and with a good powder morphology.
DE 4406964 claims a supported catalyst system which is prepared by reacting a finely divided support with an &agr;-trialkoxy-&ohgr;-haloalkyl compound and a metallocene having heterofunctional groups as cyclopentadienyl system and then with a quaternizing agent and, if desired, with an aluminoxane compound. These catalyst systems are suitable for the preparation of polyolefins.
It is an object of the present invention to provide a supported catalyst system having particularly high activity and an environmentally friendly and economical process for preparing polymers.
This object is achieved by a supported catalyst system comprising at least one metallocene component, at least one cocatalyst component and at least one modified inorganic oxide of silicon, aluminum or mixtures thereof, wherein the modified oxide contains organic silicon radicals containing at least one of the groups nitrogen, fluorine, phosphorus or sulfur.
According to the invention, the catalyst system is prepared by mixing at least one metallocene and at least one modified support.
The metallocene component of the catalyst system of the invention can in principle be any metallocene. Preference is given to chiral metallocene. In addition, further substituents such as halogen, alkyl, alkenyl, alkoxy, aryl or alkylaryl groups can be bonded to the central metal atom. The central metal atom is preferably an element of transition group III, IV, V or VI of the Periodic Table of the Elements, for example Ti, Zr or Hf. For the purposes of the present invention, cyclopentadienyl ligands are unsubstituted cyclopentadienyl radicals and substituted cyclopentadienyl radicals such as methylcyclopentadienyl, indenyl, 2-methylindenyl, 2-methyl-4-phenylindenyl, tetrahydroindenyl, benzoindenyl, fluorenyl, benzofluorenyl, tetrahydrofluorenyl, octahydrofluorenyl radicals. The &pgr;-ligands, e.g. cyclopentadienyl ligands, can be bridged or unbridged, with single and multiple bridges, even via ring systems, being possible. The term metallocenes also includes compounds having more than one metallocene fragment, known as multinuclear metallocenes. These can have any substitution pattern and bridging variants. The individual metallocene fragments of such multinuclear metallocenes can either be of the same type or be different from one another. Examples of such multinuclear metallocenes are described, for example, in EP-A-632063, JP-A-04/80214, JP-A-04/85310, EP-A-654476.
In addition, the term metallocene includes monocyclopentadienyl systems such as bridged cyclopentadienylamido complexes.
Preference is given to metallocenes of group IVb of the Periodic Table of the Elements, for example titanium, zirconium or hafnium, particularly preferably zirconium.
The metallocenes are preferably ones having the formula I below
where
Connolly Bove & Lodge & Hutz LLP
Rabago R.
Targor GmbH
Wu David W.
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