U.S. patent application number 09/924929 was filed with the patent office on 2002-03-14 for heterogeneous catalyst components for olefins polymerization, preparation process and use thereof.
This patent application is currently assigned to REPSOL QUIMICA S.A.. Invention is credited to Canas, Pilar LaFuente, Garcia, Begona Pena, LaFuente, Antonio Munoz-Escalona, Llatas, Luis Mendez, Royo, Jose Sancho, Vega, Wilfried Michiels.
Application Number | 20020032294 09/924929 |
Document ID | / |
Family ID | 8298076 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020032294 |
Kind Code |
A1 |
Llatas, Luis Mendez ; et
al. |
March 14, 2002 |
Heterogeneous catalyst components for olefins polymerization,
preparation process and use thereof
Abstract
It is shown metallocenes with functionalized bridge of formula 1
wherein M represents a transition metal of groups 3, 4, 5 or 6, L
represents cyclopentadieliyl-type ligands, Y represents a halogen
and which can own one or various bridges between uritics L. At
least one of these bridges is functionalized through a group
constituted by the union between a halogen atom and a silicon,
germanium or tin atom. It is also shown a method for the synthesis
of these metallocene compounds starting from the corresponding
metallic halure and a precursor of the ligand which has leaving
groups. These metallocene compounds are used as catalyst precursors
for the homopolymerization and copolymerization of olefins. It is
also shown methods for supporting these metallocenes on inorganic
solids in order to obtain solid catalyst systems for olefins
polymerization processes in a heterogeneous phase.
Inventors: |
Llatas, Luis Mendez;
(Mostoles, ES) ; LaFuente, Antonio Munoz-Escalona;
(Madrid, ES) ; Royo, Jose Sancho; (Madrid, ES)
; Canas, Pilar LaFuente; (Madrid, ES) ; Vega,
Wilfried Michiels; (Alcala De Henares, ES) ; Garcia,
Begona Pena; (Madrid, ES) |
Correspondence
Address: |
John Palmer
LADAS & PARRY
Suite 2100
5670 Wilshire Boulevard
Los Angeles
CA
90036-5679
US
|
Assignee: |
REPSOL QUIMICA S.A.
|
Family ID: |
8298076 |
Appl. No.: |
09/924929 |
Filed: |
August 8, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09924929 |
Aug 8, 2001 |
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09016211 |
Jan 30, 1998 |
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6278009 |
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Current U.S.
Class: |
526/348 |
Current CPC
Class: |
C08F 210/16 20130101;
C08F 4/61916 20130101; C08F 4/61927 20130101; C08F 210/14 20130101;
C08F 2500/03 20130101; C08F 10/00 20130101; C08F 4/61912 20130101;
C08F 10/00 20130101; C08F 110/02 20130101; C08F 210/16 20130101;
C08F 10/00 20130101 |
Class at
Publication: |
526/348 |
International
Class: |
C08F 210/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 1, 1997 |
ES |
P9700201 |
Claims
1. A metallocene catalyst component for olefin polymerization
comprising a metallocene compound characterized by the following
formula: 11wherein: Y is halogen; M is a transition metal of groups
3-6 of the periodic table; each L is independently selected from a
cyclopentadienyl-type unity, including indenyl or fluorenyl,
substituted or not and the substituents being equal or different,
united to M through a .pi. bond; Z is a group that forms a union
bridge between the two unities L, which can have between 0 and 20
carbon atoms and between 0 and 5 oxygen, sulfur, nitrogen,
phosphorus, silicon, germanium, tin or boron atoms; E is a spacer
group that unites Z and Y and can have between 0 and 20 carbon
atoms and between 0 and 5 oxygen, sulfur, nitrogen, phosphorus,
silicon, germanium, tin or boron atoms. It is characterized for
having in its skeleton at least one silicon, germaniun) or tin
atom, which the substituent Y is united to; o is a number of value
0 or 1; k is a nunber ofvalue 1, 2 or 3; m is a number equal to or
higher than 2 and coinciding with the oxidation state of the
transition metal; j is a number of value 0 or 1 with the condition
that its value is 1 at least once; when j is 1 and o is 0, Z is
characterized by having at least one silicon, germanium or tin atom
which Y is directly united to; with the proviso that the compound
does not have general formulaX.sub.m-M.sup.1(L'-M.sup.2(R.sup.1R-
.sup.2)-A'-Z'R.sup.3.sub.o-Hal.sub.p-).sub.n,wherein M.sup.1 is a
metal of group 4, 5 or 6 of the periodic table, each X is
independently selected from hydrogen, halogen or a C.sub.1-C.sub.40
carbon-containing rest; m' is equal to 1, 2 or 3; n' is equal to 1
or 2; each L' is independently a n ligand, which coordinates to the
central atom M.sup.1; each M.sup.2 is independently selected from
silicon, germanium or tin; R.sup.1 is a C.sub.1-C.sub.20
carbon-containing group; R.sup.2 is a C.sub.1-C.sub.20
carbon-containing group or a .pi. ligand, which coordinates to the
central atom M.sup.1; each A' is independently a divalent
C.sub.1-C.sub.40 carbon-containing rest; each Z' is independently
selected from boron, silicon, germanium or tin; each R.sup.3 is
independently selected from hydrogen or a C.sub.1-C.sub.20
carbon-containing rest; o' is equal to 0, 1 or 2; each Hal is
independently selected from a halogen atom; p' is equal to 1, 2 or
3.
2. A catalyst component according to claim 1, characterized in that
the metallocene compound has formula: 12wherein: Y is halogen; M is
a transition metal of groups 3, 4, 5 or 6 of the periodic table;
each L is independently selected from a cyclopentadienyl-type
unity, including indenyl or fluorenyl, substituted or not and the
substituents being equal or different, united to M through a .pi.
bond; Q is an element of group 13, 14 or 15; E is a spacer group
that unites Q and Y and can have between 0 and 20 carbon atoms and
between 0 and 5 oxygen, sulfur, nitrogen, phosphorus, silicon,
germanium, tin or boron atoms and it is characterized by having in
its skeleton at least one silicon, germanium or tin atom, which the
substituent Y is united to; R is an atom of hydrogen, halogen,
halocarbon, substituted halocarbon, C.sub.1-C.sub.20 alkyl,
C.sub.2-C.sub.20 alkenyl, C.sub.6-C.sub.20 aryl, C.sub.7-C.sub.40
alkylaryl, C.sub.7-C.sub.40 arylalkyl, C.sub.8-C.sub.20
arylalkenyl, alkoxy, siloxy and combinations thereof; A, equal to
or different from each other, is a bridge group between unities L
and Q constituted either by only one divalent atom of gorup 16,
preferably --O--, or by a trivalent monosubstituted element of
group 15, preferably >N--R, R being define above, or a
tetravalent disubstituted element of group 14, preferably
>C(R).sub.2 or >Si(R).sub.2, R being define above, or by a
chain of 2 or more atoms substituted or not, this chain being
preferably of type --C--C--, --C--Si--, --Si--Si--, --Si--O--,
--C--O--, --C--N--, --C--C--C, --C--Si--C--, --si--O--Si--; o is a
number of value 0 or 1; k is a number of value 1, 2 or 3; m is a
number equal to or higher than 2 and coinciding with the oxidation
state of the transition metal; p, n, l are numbers of value 0 or 1,
j is a number of value 0 or 1 with the condition that its value is
1 at least once; when J is 1 and o is 0, Q is a silicon, germanium
or tin atom; with the proviso that the compound does not have
general formulaX.sub.m-M.sup.1(L'-M.sup.2(R.sup.1R-
.sup.2)-A'-Z'R.sup.3.sub.o-Hal.sub.p-).sub.n, wherein M.sup.1 is a
metal of group 4, 5 or 6 of the periodic table, each X is
independently selected from hydrogen, halogen or a C.sub.1-C.sub.40
carbon-containing rest; m' is equal to 1, 2 or 3; n' is equal to 1
or 2; each L' is independently a .pi. ligand, which coordinates to
the central atom M.sup.1; each M.sup.2 is independently selected
from silicon, germanium or tin; R.sup.1 is a C.sub.1-C.sub.20
carbon-containing group; R.sup.2 is a C.sub.1-C.sub.20
carbon-containing group or a .pi. ligand, which coordinates to the
central atom M.sup.1; each A' is independently a divalent
C.sub.1-C.sub.40 carbon-containing rest; each Z' is independently
selected from boron, silicon, germanium or tin; each R.sup.3 is
independently selected from hydrogen or a C.sub.1-C.sub.20
carbon-containing rest; o' is equal to 0, 1 or 2; each Hal is
independently selected from a halogen atom; p' is equal to 1, 2 or
3.
3. A catalyst component according to claims 1-2, characterized in
that the metallocene compound has formula: 13Wherein: L, M, m, Y,
R, l, n and A have already been defined; T is selected from:
silicon, germanium or tin.
4. A catalyst component according to claims 1-2, characterized in
that the metallocene compound has formula: 14wherein: L, M, m, Y,
R, E, l, n and A have already been defined; T is selected from:
silicon, germanium or tin.
5. A heterogeneous catalyst component for the polymerization of
olefins obtained from an inorganic solid that contains hydroxy
groups and a catalyst component according to claims 1-4.
6. A heterogeneous catalyst component for the polymerization of
olefins according to claim 5 consisting of: an inorganic solid that
contains hydroxy groups and that has been previously modified
through reaction with a compound of formula: 15being: R: atom of
hydrogen, halogen, halocarbon, substituted halocarbon, C.sub.1-20
alkyl, C.sub.2-20 alkenyl, C.sub.6-20 aryl, C.sub.7-40 alkylaryl,
C.sub.7-40 arylalkyl, C.sub.8-20 arylalkenyl, alkoxy, siloxy and
combinations thereof; X: halogen or group OR.sup.4 wherein R.sup.4
has the same meaning given above; P: NH.sub.2, NHR, SH, OH or PHR;
v+z+w=3, v being different from 0; t and u are comprised between 0
and 10; and a catalyst component according to claims 1-4.
7. A heterogeneous catalyst component for the polymerization of
olefins according to claims 5-6 characterized in that the inorganic
solid is selected from the group comprising: silica, silicates,
carbonates, phosphates, clays, metal oxides and mixtures
thereof.
8. A catalyst system comprising: a catalyst component according to
claims 1-7 in combination with a cocatalyst selected from the group
comprising: non-coordinatinig compounds of alumoxane-type, modified
alumoxane-type, boron compounds and combinations thereof.
9. A catalyst system according to claim 8 characterized in that the
cocatalyst is selected from the group comprising: methylalumoxane,
dimethylaniline tetrakis(pentafluorophenyl)boron or
trispentafluorophenylborane.
10. A process for the preparation of the heterogeneous catalyst
component characterized in that the compound of claims 1-4 and the
inorganic support are put in contact by using tetrahydrofurane as
solvent.
11. A process for the polymerization of alpha-olefins, optionally
in combination with a cyclic olefin and/or a diene, characterized
by the presence of a catalyst component according to claims
1-7.
12. A process according to claim 11 characterized in that the
monomers are selected from the group comprising: ethylene, propene,
1-butene, 1-hexene, 4-methyl-1-pentene, 4-octene and mixtures
thereof.
13. A process according to claim 11-12 for the copolymerization of
ethylene in combination with a comonomer selected from the group
comprising: propene, 1-butene, 1-hexene, 4-methyl-1-pentene,
1-octene, cyclic olefins and mixtures thereof.
Description
STATE OF THE ART PRIOR TO THE INVENTION
[0001] It is well known that metallocene compounds such as
bis(cyclopentadienyl)titanium dialkyl or
bis(cyclopentadienyl)zirconium dialkyl in combination with alkyl
aluminiums act as catalysts for olefin polymerization in
homogeneous phase. Thus, German patent DE-2,608,863 describes the
use of bis(cyclopentadienyl)titanium dialkyl in combination with
trialkylaluminium and a controlled quantity of water in olefins
polymerization.
[0002] The controlled hydrolysis of alkyl aluminiums gives rise to
the formation of species containing an Al--O bond (aluminoxane)
which are real co-catalysts in the polymerization of olefins with
metallocenes. Kaminsky (Adv. Organomet. Chem. b 1980, 18, 99) shows
that aluminoxanes in combination with dichlorometallocenes produce
catalyst systems which are very active in ethylene
polymerization.
[0003] It is also possible (Turner, EP 277004 and Ewen et al. EP
426637) to use co-catalysts formed by bulky boron compounds which,
acting as non-coordinative anions, stabilize the cationic form of
the metallocene without preventing the incorporation of the olefin
in the polymerization process.
[0004] The polymerization processes that use homogeneous catalyst
systems produce high polymerization activities. However, most
industrial processes require heterogenous catalyst systems which on
the one hand produce polymers with a controlled morphology, but on
the other hand have an activity of the order of the homogeneous
systems.
[0005] In European patent EP 206794 it is described heterogeneous
catalysts obtained through simultaneous or subsequent (in any
order) addition of aluminoxanie and metallocene onto an inorganic
support.
[0006] This process, according to patent EP 260130, can also be
applied to multicomponent systems. These catalysts are those which
contain various metallocenes or one metallocene and one
non-metallocene compound of a transition element. In this way,
polyolefins with a multimodal molecular weight distribution are
obtained.
[0007] In patents EP 361866, EP 323716, EP 367503, EP 368644 and US
5057475 it is described the preparation of a heterogeneous catalyst
system composed by one aluminoxane and one metallocene
characterized in that the aluminoxane is generated "in situ"
through reaction of a trialkylaluminium with undehydrated silica.
The use of this catalyst system in .alpha.-olefins polymerization
gives rise to high activities.
[0008] Another well known technique used in the preparation of
heterogeneous catalysts is the chemical modification of the
inorganic support. In patents EP 474391 and EP 314797 it is
described a process wherein the support, before the addition of the
metallocene, is treated with an organoaluminium compound which
reacts with the hydroxyl groups present on the silica surface.
[0009] The above described catalyst systems present the drawback
that the catalyst is not tightly enough bonded to the support so
that the separation of the metallocene from the support can occur,
producing polymerization in solution, which prejudices the
morphology of the obtained polymer.
[0010] As a consequence of that, methods for obtaining the
formation of a chemical bond between the support and the
metallocene are looked for. A possible solution is the formation of
a chemical bond by reacting a functionalized metallocene and a
partly dehydrated silica. In patents EP 293815 and DE 3718888 it is
described a method for the preparation of a supported catalyst
wherein the chemical bond between the support and the metallocene
is obtained by reacting an alkoxysilane group united to the
metallocene and an hydroxy group of the support. The synthesis of
this catalyst is difficult and very low yields are obtained.
Furthermore, the activity in the polymerization of the olefins of
the resulting catalysts is rather low.
[0011] Patent DE 3840772 describes the use of metallocenes
functionialized with vinyl groups united to the cyclopentadienyl
ring. Heterogeneous systems are obtained by reacting the double
bond with polysiloxanes in the presence of a fit catalyst. This
method presents the drawback of needing an additional purification
process for removing this catalyst.
[0012] According to patent EP 628566, it is possible to prepare
heterogeneous catalysts by reacting ligands already chemically
bonded to the support first with alkyllithium and then with metal
halides MX.sub.4 (wherein M is a transition metal and X is a
halide). This process produces catalysts with the metallocene
tightly bonded to the support. They are used in olefins
polymerization in combination with alumoxanes. Also in this case it
is necessary a purification of the catalyst system to eliminate the
residues of the reagents used in its formation.
[0013] EP-A-757053 discloses new metallocenes characterized by the
following general formula
X.sub.mM(L-M.sup.2(R.sup.1R.sup.2)-A-ZR.sup.3.s-
ub.oHal.sub.p).sub.n, wherein M is a metal of group 4, 5 or 6 of
the periodic table, each X is independently selected from hydrogen,
halogen or a C.sub.1-C.sub.40 carbon-containing rest; m is equal to
1, 2 or 3; n is equal to 1 or 2; each L is independently a n
ligand, which coordinates to the central atom M; each M.sup.2 is
independently selected from silicon, germanium or tin); R.sup.1 is
a C.sub.1-C.sub.20 carbon-containing group; R.sup.2 is a
C.sub.1-C.sub.20 carbon-containing group or a n ligand, whichl
coordinates to the central atom M; each A is independently a
divalent C.sub.1-C.sub.40 carbon-containing rest; each Z is
independently selected from boron, silicon, germanium or tin; each
R.sup.3 is independently selected from hydrogen or a
C.sub.1-C.sub.20 carbon-containing rest; o is equal to 0, 1 or 2;
each Hal is independently selected from a halogen atom; p is equal
to 1, 2 or 3.
[0014] These compounds are characterized by the presence of a
hydrocarbon bridge connecting two silicon, germanium or tin atoms
to whom the halogen atom is connected. This characteristic makes
them especially suitable in the preparation of supported
catalysts.
[0015] An object of the present invention is to provide new
catalyst component comprising a bridged metallocene having a Si--Cl
functional group bonded to bridge. These compounds can be supported
on silica.
DESCRIPTION OF THE INVENTION
[0016] In this invention it is described organo metallic compounds
of transition metals of groups 3, 4, 5 or 6 of the periodic table
of the metallocene-type. Besides, the compounds of the present
invention are characterized in that they have at least one link or
bridge between the cyclopentadienyl type unities. The bridge is
characterized in that it shows at least one functionality, either
included in the bridge or bonded to it, this being a Si--Y, Ge--Y
or Sn--Y-type unity, preferably Si--Y, Y being halogen; preferably
Y is chlorine or bromine.
[0017] In the present invention it is described the synthesis of
these metallocenes as well as methods for supporting these
compounds onto solids.
[0018] The invention refers in general to metallocenes represented
by the following formula (Formula I) 2
[0019] wherein:
[0020] Y is halogen;
[0021] M is a transition metal of groups 3-6 of the periodic
table;
[0022] each L is selected from a cyclopentadienyl-type unity,
including indenyl or fluorenyl, substituted or not and the
substituents being equal or different, united to M through a .pi.
bonlti; Z is a group that forms a union bridge between the two
unities L, which can have between 0 and 20 carbon atoms and between
0 and 5 oxygen, sulfur, nitrogen, phosphorus, silicon, germanium,
tin or boron atoms; E is a spacer group that unites Z and Y and can
have between 0 and 20 carbon atoms and between 0 and 5 oxygen,
sulfur, nitrogen, phosphorus, silicon, germanium, tin or boron
atoms. It is characterized for having in its skeleton at least one
silicon, germanium or tin atom, which the substituent Y is united
to;
[0023] o is a number of value 0 or 1;
[0024] k is a number of value 1, 2 or 3;
[0025] m is a number equal to or highler than 2 and coinciding with
the oxidation state of the transition metal;
[0026] j is a number of value 0 or 1 with the condition that its
value is 1 at least once; when j is 1 and o is 0, Z is
characterized by having at least one silicon, germanium or tin atom
which Y is directly united to;
[0027] with the proviso that the conipounid does not have general
fornula
X.sub.mM.sup.1(L'-M.sup.2(R.sup.1R.sup.2)-A'Z'R.sup.3.sub.oHal.sub.p).sub.-
n,
[0028] wherein M' is a metal of group 4, 5 or 6 of the periodic
table, each X is independently selected from hydrogen, halogen or a
C.sub.1-C.sub.40 carbon-containing rest; m' is equal to 1, 2 or 3;
n' is equal to 1 or 2; each L' is independently a n ligand, which
coordinates to the central atom M.sup.1; each M.sup.2 is
independently selected from silicon, germanium or tin; R.sup.1 is a
C.sub.1-C.sub.20 carbon-containing group; R.sup.2 is a
C.sub.1-C.sub.20 carbon-containing group or a n ligand, which
coordinates to the central atom M.sup.1; each A' is independently a
divalent C.sub.1-C.sub.40 carbon-containing rest; each Z' is
independently selected from boron, silicon, germanium or tin; each
R.sup.3 is independently selected from hydrogen or a
C.sub.1-C.sub.20 carbon-containing rest; o' is equal to 0, 1 or 2;
each Hal is independently selected from a halogen atom; p' is equal
to 1, 2 or 3.
[0029] The invention preferably refers to metallocenes represented
by the following formula (formula II): 3
[0030] wherein:
[0031] Y is halogen;
[0032] M is a transition metal of groups 3, 4, 5 or 6 of the
periodic table;
[0033] each L is selected from a cyclopentadieniyl-type unity,
including indenyl or fluorenyl, substituted or not and the
substituents being equal or different, united to M through a .pi.
bond;
[0034] Q is an element of group 13, 14 or 15;
[0035] E is a spacer group that unites Q and Y and can have between
0 and 20 carbon atoms and between 0 and 5 oxygen, sulfur, nitrogen,
phosphorus, silicon, germanium, tin or boron atoms and it is
characterized by having in its skeleton at least one silicon,
germanium or tin atom, which the substituent Y is united to;
[0036] R is selected from the group comprising: hydrogen, halogen,
halocarbon, substituted halocarbon, C.sub.1-C.sub.20 alkyl,
C.sub.1-C.sub.20 alkenyl, C.sub.6-C.sub.20 aryl, C.sub.7-C.sub.40
alkylaryl, C.sub.7-C.sub.4, arylalkyl, C.sub.8-C.sub.20
arylalkenyl, alkoxy, siloxy and combinations thereof; A, equal to
or different from each other, is a bridge group between unities L
aud Q constituted either by only one divalent atom of group 16,
preferably --O--, or by a trivalent monosubstituted element of
group 15, preferably >N--R, R being defined above, or a
tetravalent disubstituted element of group 14, preferably
>C(R).sub.2 or >Si(R).sub.2, R being defined above, or by a
chain of 2 or more atoms substituted or not, this chain being
preferably of type --C--C--, --C--Si--, --Si--Si--, --Si--O--,
--C--O, --C--N--, --C--C--C, --C--Si--C--, --Si--O--Si--;
[0037] o is a number of value 0 or
[0038] k is a number of value 1, 2 or 3;
[0039] m is a number equal to or higher than 2 and coinciding with
the oxidation state of the transition metal;
[0040] p, n, 1 are numbers of value 0 or 1.
[0041] j is a number of value 0 or 1 with the condition that its
value is 1 at least once; when j is 1 and o is 0, Q is a silicon,
germaniun or tin atom;
[0042] with the proviso that the compound does not have general
formula
X.sub.m--M.sup.1(L'--M.sup.2(R.sup.1R.sup.2)--A'--Z'R.sup.3.sub.o--Hal.sub-
.---).sub.n--,
[0043] wherein M.sup.1 is a metal of group 4, 5 or 6 of the
periodic table, each X is independently selected from hydrogen,
halogen or a C.sub.1-C.sub.40 carbon-containing rest; m' is equal
to 1, 2 or 3; n' is equal to 0 or 2; each L' is independently a n
ligand, which coordinates to the central atom M.sup.1; each M.sup.2
is independently selected from silicon, germanium or tin; R.sup.1
is a C.sub.1-C.sub.20 carbon-containing group; R.sup.2 is a
C.sub.1-C.sub.2, carbon-containing group or a .pi. ligand, which
coordinates to the central atom M.sup.1; each A' is independently a
divalent C.sub.1-C.sub.40 carbon-containing rest; each Z' is
independently selected from boron, silicon, germanium or tin; each
R.sup.3 is independently selected fromi hydrogen or a
C.sub.1-C.sub.20 carbon-containing rest; o' is equal to 0, 1 or 2;
each Hal is independently selected from a halogen atom; p' is equal
to 1, 2 or 3.
[0044] In the most preferred embodiment the invention refers to
metallocenes having the following general formulas (III) and (IV)
4
[0045] herein:
[0046] L, M, m, Y, E, R, I, n have already been defined; C is a
carbon atom; T is selected from: silicon, germanium or tin.
[0047] What follows are descriptive and non-limiting examples of
the structural formulas of some metallocene compounds according to
the present invention: 5
[0048] In these formulas the following symbols have been used:
[0049] Y, R and M: above defined
[0050] Cp: cyclopentadienyl or substituted cyclopentadienyl ring,
also including in this definition substituted or not indenyl rings
and substituted or not fluorenyl rings, Cp being able to represent
in the same formula equal or different rings.
[0051] The synthesis of the functionalized metallocenes object of
the present invention can be obtained according to the general
method represented in the following scheme. 6
[0052] being:
[0053] Y, Z, L, E, M, j, m and o defined above;
[0054] S: leaving group united to the cyclopentadienyl ring,
preferably constituted by a unity T(R.sup.4).sub.3, T being
silicon, germanium or tin and R is C.sub.1-C.sub.20 alkyl.
[0055] S represents preferably groups Si(CII.sub.3).sub.3 and
Sn(CII.sub.3).sub.3. In case represented by this scheme, S can
represent unities equal or different; in general, the union L--S
can represent an ionic, s or .pi. bond or a combination
thereof.
[0056] The union L--M always represents a bond with a high .pi.
character.
[0057] Preferred compounds of general formula III can be obtained
according to the following scheme: 7
[0058] The synthesis of functionalized metallocenes having a carbon
bridge as depicted in formula IV could be achieved following the
general procedure described in this document starting from a
suitable ligand: 8
[0059] In order to achieve a suitable functionialized ligand, an
olefinically unsaturatcd precursor having the unsaturation within
unit E in the formula could be used. Reacting this precursor under
hydrosilylation, hydrogermanilation or hydrostannilation conditions
the suitable functional group (Si--Y, Ge--Y or Sn--Y) could be
obtained.
[0060] Alternatively, a functionalized metallocene according to
formula IV could be obtained from a metallocene already having an
olefinic unsaturation as part of unit E.
[0061] Metallocenes of this type are known in the current
literature, for example EP 685495 (Phillips). The functionalization
of the metallocene could be achieved again by reacting it under
hydrosilylation, hydrogermanilation or hydrostannilation conditions
to attach the suitable functional group (Si--Y, Ge--Y or
Sn--Y).
[0062] In order to illustrate the different approaches towards the
synthesis, the followilng scheme of a compound having the structure
Cl.sub.3SiCH.sub.2CH.sub.2CH.sub.2CH.sub.2C(CH.sub.3)Cp.sub.2ZrCl.sub.2
is shown. All the reactive steps shown in this scheme (represented
by an arrow) can be of common knowledge for a person skilled in the
art of metallocene synthesis and can be obtained by employing
reagents different from those shown in the scheme.
[0063] The procedure employed for step (a) can be learned, for
example, from Stone et al. In J. Org. Chem. 1984, 49, 1849. The
procedure of step (b) call be learned, for example, from J.
Organomet. Chem., 1992, 435, 299, or J. Chem. Soc., Dalton Trans.
1994, 657 or EP 685495. The procedure for step (c) can be learned
from U.S. Pat. No. 5,191,132. Step (d) is the obtaining of the
dianion and could be achieved with many different reagents (e.g.
Li, Na, K, BuLi, BuMgBr, etc.), here BuLi is shown in order to
illustrate one of the most popular reactants employed. Step (e) is
also of very common use in the synthesis of metallocenes, see
again, for example, J. Organomet. Chem., 1992, 435, 299, or J.
Chem. Soc., Dalton Trans. 1994, 657 or EP 685695. Procedures for
steps (I), (g) or (j) can be learned from the present document but
also from Organometallics 1995, 14, 177 or Angew. Chem. Int. Ed.
Engl., 1994, 33, 1479. Hydrosilylation [steps (h) and (i)] can also
be achieved with different reagents, being
H.sub.2PtCl.sub.6.multidot.6H.sub.2O one of the most commonly
employed (see for example Adv. Organomet. Chem. 1979, 17, 407 or J.
Fluorine Chem. 1994, 68, 71 or EP 628566). 9
[0064] These processes for the synthesis of metallocenes with
functionalized bridge can be done in the presence of solvent or
not. In case a solvent is used, this can be preferably an aliphatic
hydrocarbon, an aromatic hydrocarbon, or mono or polyhalogen
containing derivatives therefrom. A mixture of two or more solvents
can be used too.
[0065] These processes for the synthesis of metallocenes with
functionalized bridge can be done in a temperature range between
-20 and 300.degree. C., preferably between 0 and 200.degree. C., or
at the reflux temperature of the used solvent system.
[0066] These processes for the synthesis of metallocenes with
functionalized bridge can be done with or without protection from
light. Another object of the present invention is to provide new
supported catalyst components showing a good productivity and
producing polyolefins characterized by a good morphology.
[0067] The supported catalyst component comprising an inorganic
support and a metallocene described in the present invention can be
prepared by adding the reagents to a fit inert solvent. Examples of
useful solvents are ethers such as tetrahydrofurane (THF), aromatic
hydrocarbons, such as toluene and aliphatic hydrocarbons such as
heptane or hexane.
[0068] The inorganic support according to the present invention
contains hydroxyl groups. Illustrative, but not limiting, examples
of supports useful in the field of the present invention are the
following: silicates, carbonates, phosphates, clays, metaloxides
and mixtures thereof. More preferably: silica, alumina,
silica-alumina, silica titanates, silica vanadates, silica
chromates, aluminium phosphates, phosphated silica and possible
mixtures thereof.
[0069] The surface area of the inorganic support is preferably
10-1000 m.sup.2/g, more preferably 150-650 m.sup.2/g. The pore
volume is preferably 0.2-4.0 cm.sup.3/g, more preferably 0.6-2.7
cm.sup.3/g. The average particle size is preferably 1-1000 microns,
more preferably 5-100 microns.
[0070] The water contained in the support can be optionally removed
before reacting the support with the metallocene. The dehydration
process can be performed by heating the support in an oven in inert
atmosphere at a temperature between 120.degree. C. and 1000.degree.
C. (preferably between 200 and 800.degree. C.). The amount of
hydroxyl groups on the support can be measured in several ways, for
example by titration with n-butylmagnesium chloride or
triethylaluminium.
[0071] The concentration of hydroxy-groups depends on the
dehydration temperature and on the support used. In case silica is
used, it can vary from 0,1 to 5 mmol OH/g of silica, preferably 0.3
to 3 mmol OH/g of silica or from 0,1 to 7 groups OH/nm.sup.2,
preferably 0.5 to 5 groups OH/nm.sup.2. Once dehydrated, the
support has to be protected from environmental humidity, for
example by storing it under inert atmosphere (nitrogen or
argon).
[0072] The inorganic support is used as such or it can be
previously modified through reaction of the hydroxy-groups with
compounds of formula V: 10
[0073] being:
[0074] R: atom of hydrogen, halogen, halocarbon, substituted
halocarbon, C.sub.1-20 alkyl, C.sub.2-20 alkenyl, C.sub.6-20 aryl,
C.sub.7-40 alkylaryl, C.sub.7-40 arylalkyl, C.sub.8-20 arylalkenyl,
alkoxy, siloxy and combinations thereof
[0075] X: halogen or group OR.sup.4 wherein R.sup.4 has the same
meaning given above
[0076] P: NH.sub.2, NHR, SH, OH or PHR
[0077] v+z+w=3, v being different from 0
[0078] t and u are comprised between 0 and 10.
[0079] Some examples of compounds of formula III are:
[0080] 3-Mercaptopropyltrimethoxysilane,
3-aminopropyltrimethxysilane, N-Phenylptopyltrimethoxysilane,
N-Methylpropyltrimethoxysilane, N-Aminopropyldimethoxymethylsilane,
3-mercaptopropyltrimethoxy-silane.
[0081] Both the functionalized metallocenes object of the present
invention and their derivatives supported onto inorganic solids can
be used in polymerization reactions in conjunction with one or
various co-catalysts. Said co-catalysts are anionic
non-coordinative compounds of alumoxane, modified alumoxane or
boron compounds type. In case boron derivatives are used, the
supported systems have to be previously treated for alkylating the
metallocene unities. This alkylation can be done by using
alkylating agents described in literature. Illustrative but
non-limiting examples of co-catalysts are: methylalumoxane (MAO),
dimethylaniline tetrakis(pentafluorophenyl)boro or
trispentafluoro-phenylborane.
[0082] The catalyst systems described in the present invention are
useful for the homo and copolymerization of .alpha.-olefins, in
suspension or in gas phase, as well as in mass polymerization at
high temperatures and pressures. The temperature can vary between
-60.degree. C. and 300.degree. C., preferably between 40.degree. C.
and 250.degree. C. The pressure can vary between 1 and 2000
atmospheres. The polymerization time can vary between 1 second and
6 hours, according to the process type.
[0083] The process is applicable to all olefins which can be
polymerized by Ziegler-Natta catalysts, it is particularly fit for
the homopolymerization of alpla-olefins from 2 to 20 carbon atoms
such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene
and similar, as well as cyclic monomers and/or dienes. It is also
fit for the copolymerization of ethylene with alpha-olefins
different from ethylene, having from 3 to 20 carbon atoms,
preferably from 3 to 6 carbon atoms, such as propylene, 1-butene
1-hexene, 4-methyl-1-pentene and similar, as well as cyclic
monomers and/or dienes. The copolymerization of more than two
alpla-olefins is possible too.
EXAMPLES
[0084] General conditions: The metallocenes synthesis was done in
all its steps under the protection of an atmosphere of dry
nitrogen, either in a dry box or by using the techniques. The used
solvents were dried before being used according to the methods
described in literature. In the following examples these
abbreviations are used for representing the written formulas:
[0085] Cp: cyclopentadienyl radical
[0086] Me: methyl radical
[0087] TMS: trimethylsilyl radical
Examnple 1
Synthesis of
((Chloromethylsilandiyl)Bis(Cyclopentadienyl))Zirconium(IV)Di-
chloride, Cl(Me)SiCp.sub.2ZrClhd 2
[0088] This example is useful for describing a zirconium
metallocene with a functionalized bridge and its synthesis.
[0089] 1.1 Preparation of the dilithium salt of
cyclopentadienyltrimethyls- ilane, CpTMSLi
[0090] A solution of 40 g (0.29 mol) of
cyclopentadienyltrimethylsilane in 300 ml of hexane is added to 200
ml of a 1.25 M solution of butyllithium in hexane. During the
addition, the reaction mixture temperature is maintained at
0-5.degree. C. After 3 h at room temperature, the obtained white
solid is settled and washed once with 150 ml of hexane. This solid
is identified as the desired product. .sup.1H-NMR
(d.sub.8-tetrahydrofura- ne) 5.95 (pseudo-t, 2H), 5.85 (pseudo-t,
2H), 0.16 (s, 911). .sup.13C-NMR (d.sub.8-tetrahydrofurane) 112.9,
111.2, 108.09, 2.89.
[0091] 1.2 Preparation of
(dichloro(methyl)silyl)(trimethylsilyl)cyclopent- adiene,
Cl.sub.2(Me)SiCpTMS
[0092] A solution of 30 ml (0.25 mol) of trichloromethylsilane and
250 ml of dry hexane is added to a suspension of 0.25 mol of
CpTMSLi and 200 ml of hexane. Then, the reaction mixture is heated
at the reflux temperature for 5 h. After cooling, the solid is
filtered and washed with 200 ml more of hexane. From the union of
the filtered product and the washing waters, after the elimination
of the solvent in vacuum, a pale yellow oil that distils at
73-74.degree. C. (2 Torr) is obtained. The obtained product is
mostly the isomer
1-(dichloro(methyl)silyl)-1-(trimethylsilyl)cyclopentad- iene.
Overall yield of steps 1.1 and 1.2: 66.7 g (92%). .sup.1H-NMR
(C.sub.6D.sub.6): 6.61 (m, 2H), 6.42 (m, 2H), 0.13 (s, 3H), 0.02
(s, 9H). .sup.13C-NMR (C.sub.6D.sub.6): 134.2, 133.6, 59.0, 2.5,
-1.1.
[0093] 1.3 Preparation of
bis(trimethylsilylcyclopentadienyl)methylchloros- ilane,
Cl(Me)Si(CpTMS).sub.2 80 ml of a 1 M solution of [CpTMS]MgCl
(chloromagnesium derivative of trimethylsilylcyclopentadienile) in
tetrahydrofurane is slowly added to a solution of 20.2 g (0.08 mol)
of [Cl.sub.2(Me)SiCpTMS] prepared according to 1.2 and 300 ml of
hexane. The reaction mixture is maintained under stirring for 18
more h at room temperature. The solid is filtered and washed with
hexane (100 ml). The solvent of the filtered product is eliminated
and the obtained oil is distilled. The pale yellow fraction that
distils at 110.degree. C. (0.5 Torr) is gathered. Yield: 15.8 g
(57%). This fraction consists in a mixture of isomers with formula
Cl(Me)Si(CpTMS).sub.2.
[0094] 1.4 Preparation of
((chloromethylsilanediyl)bis(cyclopentadienyl))z-
irconium(IV)dichloride, Cl(Me)Si(Cp).sub.2ZrCl.sub.2
[0095] A solution of 10.14 g (0.029 mol) of Cl(Me)Si(CpTMS).sub.2
and 200 ml of toluene is quickly transferred to 6.69 g (0.029 mol)
of ZrCl.sub.4 in a container protected from light. This is
immediately introduced in a bath at 110.degree. C. and maintained
under stirring for 3 h. Then, it is filtered hot and the solution
is immediately cooled in a freezer causing the crystallization of
the product, which is gathered through filtration. Yield: 7.7 g
(72%). Zr 24.6% (theor.: 24.7%); Cl 28.1% (theor.: 28.8%).
.sup.1H-NMR (CDCl.sub.3): 7.04 (m, 2H), 7.00 (mn, 2H), 6.17 (m,
2H), 5.97 (m, 2H), 1.12 (s, 3H). .sup.13C-NMR (CDCl.sub.3): 129.5,
128.2, 114.5, 113.4, 108.2, -1.7. Mass spectrometry: M.sup.+ m/z
(relative intensity) 373.9 (14%) 372.9 (8%), 371.9 (41%), 370.9
(18%), 369.9 (80%), 368.9 (36%), 367.9 (100%), 366.9 (30%), 365.9
(71%) [M.sup.+ calculated for C.sub.11H.sub.11Cl.sub.3SiZr: 373.9
(13%), 372.9 (8%), 371.9 (41%), 370.9 (18%), 369.9 (77%), 368.9
(33%), 367.9 (100%), 366.9 (28%), 365.9 (73%)]
Example 2
Synthesis of
((Chloromethylsilanediyl)Bis(Cyclopentadienyl))Hafnium(IV)Dic-
hloride, Cl(Me)SiCp.sub.2HfCl.sub.2
[0096] This example describes a hafnium metallocene with
functionalized bridge and its synthesis.
[0097] A solution of 2.15 g (6.1 mmol) of Cl(Me)Si(CpTMS).sub.2 and
50 ml of toluene is quickly added to 1.95 g (6.1 mmol) of
HfCl.sub.4 in a container protected from light. Then, it is soaked
in an oil bath previously heated at 110.degree. C. It is maintained
under stirring in these conditions for 2 h, before filtering it
hot. The so obtained solution is cooled in a freezer. In this way,
it is produced the crystallization of the desired product, which is
identified as Cl(Me)SiCp.sub.2HfCl.sub.2. Yield: 2.1 g (78%).
.sup.1H-NMR (CDCl.sub.3): 6.95 (m, 2H), 6.90 (m, 2H), 6.10 (m, 2H),
5.90 (m, 2H), 1.12 (s, 3H). .sup.13C-NMR (CDCl.sub.3): 128.2,
126.9, 112.4, 111.4, 109.5, -1.7. Masses spectrometry: M.sup.+ m/z
(relative intensity) 460.9 (4%), 459.9 (19.5%), 458.9 (19%), 457.9
(65%), 456.9 (50%,), 455.9 (100%), 454.9 (60%), 453.9 (55%),452.9
(31%),451.9 (10%) [M.sup.+ calculated for
C.sub.11H.sub.11Cl.sub.3SiHf: 460.9 (4%), 459.9 (21%), 458.9 (19%),
457.9 (70%), 456.9 (45%), 455.9 (100%), 454.9 (54%), 453.9 (51%),
452.9 (28%), 451.9 (8%)].
Example 3
Impregnation of Cl(Me)SiCp.sub.2ZrCl.sub.2 Onto Silica Calcined at
400.degree. C.
[0098] This example shows an impregnation method of a metallocene
with a functionalized bridge onto an inorganic support.
[0099] The impregnation reaction of the metallocene compound
functionalized in the bridge onto the inorganic support is achieved
in a glass reactor of a capacity of 250 ml, equipped with a
mechanical stirrer in a thermostatic bath, wherein 2.22 g of silica
(previously calcined at 400.degree. C., with a concentration of
groups OII of 1.55 mmol/g) and 50 ml of dry toluene are added. To
this suspension 0.218 g of Cl(Me)SiCp.sub.2ZrCl.sub.2 is added in
inert atmosphere and it is heated at 70.degree. C. under constant
stirring for 24 hours. The solid is filtered and washed several
times with dry toluene (5.times.100 ml) and it is carried to
dryness in vacuum. The final solid has a Zr content of 1.87% by
weight. This supported metallocene catalyst is stable under
nitrogen for long periods of time.
Example 4
Impregnation Of Cl(Me)SiCP.sub.2ZrCl.sub.2 Onto Silica Calcined At
800.degree. C.
[0100] 4.1 Method A
[0101] The mipregnation reaction of the metallocene compound
functionalized in the bridge onto an inorganic support is done in a
glass reactor of a capacity of 250 ml, equipped with a mechanical
stirrer and a thermostatic bath, wherein 3.4 g of silica
(previously calcined at 800.degree. C., with a concentration of
groups OH of 0.796 mmol/g) and 50 ml of dry toluene are added. To
this suspension 1.497 g of Cl(Me)SiCp.sub.2ZrCl.sub.2 in 50 ml of
dry toluene is added in inert atmosphere and it is heated at
40.degree. C. under constant stirring for 24 hours. The solid is
filtered and washed several times with dry toluene (5.times.100 ml)
and it is carried to dryness in vacuum. The final solid has a Zr
content of 1,16% by weight. This supported metallocene catalyst is
stable under nitrogen for long periods of time.
[0102] 4.2 Method B
[0103] The impregnation reaction of the metallocene compound
functionalized in the bridge onto an inorganic support is done in a
glass reactor of a capacity of 250 ml, equipped with a mechanical
stirrer and a thermostatic bath, wherein 3.08 g of silica
(previously calcined at 800.degree. C., with a concentration of
groups OH of 0.796 mmol/g) and 50 ml of dry THF are added. To this
suspension 1.35 g of Cl(Me)SiCp.sub.2ZrCl.sub.2 in 50 ml of dry THF
is added in inert atmosphere and it is heated at 40.degree. C.
under constant stirring for 24 hours. The solid is filtered and
washed several times with dry toluene (5.times.100 ml) and it is
carried to dryness in vacuum. The final solid hasa Zr content of
0,53% by weight. This supported metallocene catalyst is stable
under nitrogen for long periods of time.
Example 5
Support Of Cl(Me)SiCp.sub.2ZrCl.sub.2 On Functionalized Silica
[0104] In order to illustrate a method for supporting a
functionalized metallocene with the bond Si--Cl within the bridge
onto amine-functionalized silica, the following two cases are
presented:
[0105] 5.1 Method A
[0106] The reaction between the metallocene and the support is
carried out in toluene according to the following procedure: into a
three necked 250 ml glass reactor with an inert atmosphere of
N.sub.2, fitted with an overhead stirrer, a connection to a
vacuum/N.sub.2 line and a septum, first are added 3,29 g of
aminopropil silica gel (with 0,9 mmol/g.+-.0,1 amino groups, from
fluka) which had been previously dried for 7 h at 200.degree. C.
under inert atmosphere and, second, a solution prepared with 50 ml
of dried toluene and 0,219 g(0,59 mmol) of
Cl(Me)SiCp.sub.2ZrCl.sub.2. The mixture is stirred during 12 h and
then the slurry is transferred to a sintered glass filter funnel
closed in order to keep an internal N.sub.2 atmosphere. The slurry
is then filtered and washed with 500 ml of dry toluene in the same
filter. The resulting solid is dried at room temperature during 72
h under vacuum and transferred inside a nitrogen dry box where it
is weighed, resulting in 3,29 g of a light cream coloured solid.
The toluene rests from the washing were evaporated to dryness
leaving behind no residue from the metallocene. The theoretical Zr
content is 1,70% (w/w).
[0107] 5.2 Method B
[0108] The same reaction as in Method A is carried out but
employing dry dichloromethane instead of toluene as the solvent for
this example. The amounts of reactants employed are: 2,75 g of
aminopropil silica gel and 0,147 (0,4 mmol) of metallocene. The
result is 2,53 g of a light cream coloured solid with a theoretical
Zr content of 1,26% (w/w). Again, the liquids from the washing
leave behind no residue from the metallocene.
Example 6
Ethylene Polymerization With Heterogeneous Catalyst
[0109] 6.1 This example describes the obtaining of a polyethylene
by using a heterogeneous catalyst system obtained according to
Example 3.
[0110] In a flask of 500 ml of capacity, dried and cleaned by a
nitrogen flux, equipped with two entries, one provided with a
rubber stopper and the other with a magnetic stirrer, 200 ml of dry
heptane are injected in a nitrogen atmosphere. Then, the flask is
introduced in a thermostatic bath and the nitrogen atmosphere is
substituted by an ethylene atmosphere through consecutive charges
and discharges of ethylene. Then, 10.0 mmol of methlylaluminoxane
are introduced by using a syringe with a hypodermic needle. The
solution being saturated with ethylene and the temperature being at
40.degree. C., 147 mg of a solid prepared according to example 3
suspended in heptane are directly injected in the flask. After 15
minutes of polymerization 1.16 g of polymer is obtained. The
activity of the catalyst system is 155 Kg Pe/mol Zr h atm.
[0111] 6.2 This example describes the obtaining of a polyethyleyne
by using a heterogeneous catalyst system obtained according to
Example 4.1
[0112] To a glass reactor of 1.3 liter, previously dried and
outgased, 600 ml of n-heptane is added. The temperature is raised
to 70.degree. C. and the solvent is stirred at 1200 rpm. When the
thermic equilibrium is achieved, the medium is saturated with
ethylene at a pressure of 2 bars. Then, 20 ml of a MAO solution in
toluene (1.5 M in total aluminium) are added. The pressure is then
raised to 4 bars with more ethylene and 2 minutes later 0.157 g of
the catalyst of example 4.1 is added. The system is led with
ethylene for 15 more minutes and then the polymerization is stopped
by preventing the ethylene flux and adding 20 ml of acidified
methanol. 3.7 g of polyethylene with a molecular weight (M.sub.w)
of 169,800 is obtained. The activity of the catalyst system is 185
Kg Polymer/mol Zr h atm.
[0113] 6.3 This example describes the obtaining of a polyethylene
by using a heterogeneous catalyst system obtained according to
example 4.2.
[0114] In a glass reactor of 1.3 liter, previously dried and
outgased, 600 ml of n-heptane is added. The temperature is raised
to 70.degree. C. and the solvent is stirred at 1200 rpm. When the
thermic equilibrium is achieved, the medium is saturated with
ethylene at a pressure of 2 bars. Then 6.7 ml of a MAO solution in
toluene (1.5 M in total aluminium) are added. The pressure is
raised to 4 bars with more ethylene and 2 minutes later 0.172 g of
the catalyst of example 4.3 is added. The system is fed with
ethylene for 15 more minutes and then the polymerization is stopped
by preventing the ethylene flux and adding 20 ml of acidified
methanol. 4.5 g of polyethylene with a molecular weight (M.sub.w)
of 151,900 is obtained. The activity of the catalyst system is 450
Kg Polymer/mol Zr h atm.
[0115] 6.4 This example describes the obtaining of a copolymer of
ethylene and 1-hexene by using a heterogeneous catalyst system with
a metallocene functionalized bridge supported onto silica obtained
according to example 4.2.
[0116] In a glass reactor of 1.3 liter, previously dried and
outgased, 600 ml of n-heptane and 10 ml of dry 1-hexene are added.
The temperature is raised to 70.degree. C. and the solvent is
stirred at 1200 rpm. When the thermic equilibrium is achieved, the
medium is saturated with ethylene at a pressure of 2 bars. 6.7 ml
of a MAO solution in toluene (1.5 M in total aluminium) is added.
The pressure is raised to 4 bars and 2 minutes later 0.172 g of the
catalyst of example 4.2 is added. The system is fed with ethylene
for 15 minutes and then the polymerization is stopped by preventing
the ethylene flux and adding 20 ml of acidified methanol. 4.0 g of
a ethylene-1-hexene copolymer with a molecular weight (M.sub.w) of
64,000 is obtained. The activity of the system is 400 Kg
Polymer/mol Zr h atm. The resulting copolymer has 1.5% in molar
content of unities deriving from hexene distributed at random.
Example 7
Copolymerization Of Ethylene And Hexene In Homogeneous Phase
[0117] 7.1 This example describes the obtaining in homogeneous
phase of an ethylene-hexene copolymer by using as catalyst system
the metallocene functionalized in the bridge
Cl(Me)SiCp.sub.2ZrCl.sub.2.
[0118] The polymerization is achieved in 600 ml of heptane in a
reactor of 1 liter of capacity. Ethylene and 1-hexene are added to
the reactor so that a pressure of 4 bars, the ethylene-hexene molar
ratio is 2.0. Then, 5.25 mmol of methylalumoxane in toluene and
then 3.5 mmol of the metallocene are added. The reaction
temperature is maintained at 70.degree. C. through a
heating/cooling system. After 15 minutes 6.5 g of copolymer with a
molecular weight (M.sub.w) of 15.548 and a (M.sub.w/M.sub.n)
polydispersity of 2 is obtained. The system activity is 1800 Kg
Polymer/mol Zr h atm. The resulting copolymer has 2.8% by mol
unities deriving from hexene distributed at random.
* * * * *