U.S. patent application number 11/985947 was filed with the patent office on 2008-05-08 for adjusting polymer characteristics through process control.
This patent application is currently assigned to NOVA Chemicals (International) S.A.. Invention is credited to Cliff Robert Baar, Peter Phung Minh Hoang, Victoria Ker, Paul Mesquita, Peter Zoricak.
Application Number | 20080108763 11/985947 |
Document ID | / |
Family ID | 36061697 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080108763 |
Kind Code |
A1 |
Hoang; Peter Phung Minh ; et
al. |
May 8, 2008 |
Adjusting polymer characteristics through process control
Abstract
Properties of a polymer produced in gas phase or slurry phase
using a dual catalyst such as polydispersity and comonomer
incorporation, may be controlled by controlling reaction parameters
such as temperature, (co)monomer pressure, hydrogen partial
pressure and the presence of non-polymerizable hydrocarbon. This
provides an easy method to control the bimodality of a polymer as
well as comonomer incorporation.
Inventors: |
Hoang; Peter Phung Minh;
(Calgary, CA) ; Baar; Cliff Robert; (Calgary,
CA) ; Ker; Victoria; (Calgary, CA) ; Zoricak;
Peter; (Calgary, CA) ; Mesquita; Paul;
(Calgary, CA) |
Correspondence
Address: |
Kenneth H. Johnson
P.O.Box 630708
Houston
TX
77263
US
|
Assignee: |
NOVA Chemicals (International)
S.A.
|
Family ID: |
36061697 |
Appl. No.: |
11/985947 |
Filed: |
November 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11156896 |
Jun 20, 2005 |
7323523 |
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11985947 |
Nov 19, 2007 |
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11006075 |
Dec 7, 2004 |
7321015 |
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11156896 |
Jun 20, 2005 |
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Current U.S.
Class: |
526/113 |
Current CPC
Class: |
C08F 210/16 20130101;
C08F 4/65912 20130101; C08F 210/16 20130101; C08F 2400/02 20130101;
C08F 4/64048 20130101; C08F 4/651 20130101; C08F 2/00 20130101;
C08F 2500/05 20130101; C08F 4/654 20130101; C08F 4/65904 20130101;
C08F 210/14 20130101; C08F 4/65916 20130101; C08F 210/16 20130101;
C08F 210/16 20130101; C08F 210/16 20130101; Y10S 526/901 20130101;
C08F 210/16 20130101; C08F 210/16 20130101; Y10S 526/905 20130101;
C08F 4/6592 20130101 |
Class at
Publication: |
526/113 |
International
Class: |
C08F 4/16 20060101
C08F004/16 |
Claims
1-21. (canceled)
22. A multimodal polyethylene resin comprising not less than 60
weight % of ethylene and up to 40 weight % of one or more C.sub.3-8
alpha olefins, said polymer having a weight average molecular
weight greater than 50,000 and a density greater than 0.89 g/cc
comprising from 10 to 90 weight % of a lower molecular weight
portion and from 90 to 10 weight % of a higher molecular weight
portion, said lower molecular weight portion having a weight
average molecular weight from 5,000 to 100,000 as estimated by
deconvolution of a GPC curve and a polydispersity greater than 3
and said higher molecular weight portion having a weight average
molecular weight from 200,000 to 800,000 as estimated by
deconvolution of a GPC curve and a polydispersity less than 10 when
prepared by a process for controlling one or more of the ratio of
high molecular weight polymer to low molecular weight polymer and
the comonomer distribution in a polymerization process selected
from the group consisting of a continuous fluidized bed gas phase
polymerization at a temperature from 50 to 120.degree. C. and a
slurry polymerization in a single reactor at a temperature from 20
to 150.degree. C. of a reaction mixture comprising one or more of
hydrogen, C.sub.1-7 non polymerizable hydrocarbons, and C.sub.2-8
olefins polymerized in the presence of a dual catalyst wherein both
catalyst components are on the same support: (i) the first
component of which comprises a catalyst of the formula: ##STR7##
wherein M is a group 4 transition metal; R.sup.1 and R.sup.6 are
independently selected from the group consisting of C.sub.1-6 alkyl
and C.sub.6-10 aryl radicals; R.sup.2 and R.sup.7 are independently
selected from the group consisting of C.sub.3-5 secondary and
tertiary alkyl radicals; R.sup.3, R.sup.4, R.sup.5, R.sup.1,
R.sup.9 and R.sup.10 are independently selected from the group
consisting of a hydrogen atom, C.sub.1-4 alkyl radicals, C.sub.6-10
aryl radicals, C.sub.1-C.sub.1 alkoxy radicals which substituents
have a Hammett .sigma..sub..rho. value of less than 0.2; and X and
X' are selected from the group consisting of a halogen atom,
C.sub.1-4 alkyl radicals, C.sub.7-12 arylalkyl radicals, C.sub.1-10
phenoxy radicals, amido radicals which may be substituted by up to
two C.sub.1-4 alkyl radicals and C.sub.1-4 alkoxy radicals; and
(ii) the second component of which comprises a catalyst of the
formula: (L).sub.n-M--(Y).sub.p wherein M is selected from the
group consisting of Ti, Zr, and Hf; L is a monoanionic ligand
independently selected from the group consisting of
cyclopentadienyl-type ligands, and a bulky heteroatom ligand
containing not less than five atoms in total of which at least 20%,
numerically are carbon atoms) and further containing at least one
heteroatom selected from the group consisting of boron, nitrogen,
oxygen, phosphorus, sulfur and silicon said bulky heteroatom ligand
being sigma or pi-bonded to M; Y is independently selected for the
group consisting of activatable ligands; n may be from 1 to 3; and
p may be from 1 to 3, provided that the sum of n+p equals the
valence state of M, and further provided that two L ligands may be
bridged and an activator, which comprises one or more steps
selected from the group consisting of: (a) altering the temperature
of the reaction by at least 2.degree. C. within the range from 50
to 120.degree. C. for a gas phase polymerization and within the
range from 20 to 150.degree. C. for a slurry phase polymerization;
(b) altering the partial pressure of the hydrogen component of the
reaction mixture by at least 0.02 psi (0.138 KPa); (c) altering the
partial pressure of one or more monomers in the reaction mixture by
not less than 10 psi (68.94 KPa); and (d) altering the amount of
non polymerizable hydrocarbon in the gas phase reaction mixture by
not less than 0.5 mole %.
23. A polyethylene film made from the resin according to claims
22.
24. A polyethylene pipe made from the resin according to claim
22.
25. A polyethylene rotomolded article made from the resin according
to claim 22.
26. A polyethylene injection molded article made from the resin
according to claim 22.
27. A polyethylene blow molded article made from the resin
according to claim 22.
28. A polyethylene geomembrane made from the resin according to
claim 22.
29. (canceled)
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a gas phase or slurry
process to control the ratio of the higher molecular weight
component and the lower molecular weight component and the
comonomer incorporation or placement (e.g. regular or reverse) in a
bimodal resin produced in the presence of a mixed catalyst system
by controlling one or more steps selected from the group consisting
of:
[0002] (a) altering the temperature of the reaction by at least
2.degree. C.;
[0003] (b) altering the partial pressure of the hydrogen component
of the reaction mixture by at least 0.02 psi;
[0004] (c) altering the partial pressure of one or more monomers or
comonomers in the reaction mixture by not less than 10 psi; and
[0005] (d) altering the amount of non polymerizable hydrocarbon in
a gas phase reaction mixture by not less than 0.5 mole %.
BACKGROUND OF THE INVENTION
[0006] The original single site catalysts of the mid 1980's, such
as a metallocene catalyst, produced resin having a narrow
polydispersity (Mw/Mn) typically in the range from about 2.5 to
3.5. Early on it was recognized that either blending such resins or
the use of different metallocene catalyst, in the same reactor
could produce bimodal resins, each component having a narrow
polydispersity and the blend having a broader polydispersity. It
was felt such resins would provide a good balance of processability
and physical properties such as resin toughness. There are an
increasing number of patents and applications in this field. U.S.
Pat. No. 4,530,914 issued Jul. 23, 1985 to Ewen et al., assigned to
EXXON Research & Engineering Co. teaches the use in the same
reactor of two metallocene catalysts each having different
propagation and termination rate constants for ethylene
polymerizations. The catalyst combination taught in the patent is
not the same as that contemplated by the present invention.
[0007] There are a number of patents wherein a bimodal resin is
produced having a controlled molecular weight distribution by using
different single site catalysts such as metallocenes in two or more
tandem reactors. United States patent application 2002/0045711 in
the name of Backman et al., published Apr. 18, 2002 is illustrative
of this type of art. The reference teaches away from the present
invention in that the present invention contemplates the use of a
single reactor, not tandem reactors.
[0008] U.S. Pat. No. 6,309,997 issued Oct. 30, 2001 teaches an
olefin polymerization catalyst using a phenoxide (preferably a
salicylaldimine) ligand for use in the polymerization of olefins.
The patent does not teach the use of mixed catalysts systems for
bimodal resins nor does it teach process control to adjust the
polymer characteristics such as bimodality and comonomer
incorporation.
[0009] United States patent application 2002/0077431 published Jun.
20, 2002 in the name of Whiteker discloses a process for the
polymerization and oligomerization of olefins in the presence of a
mixed catalyst system in a single reactor. The catalyst system as
disclosed comprises a first component similar to the first
component in the catalyst system of the present invention except
that at least one of substituents R.sup.3, R.sup.4, R.sup.5,
R.sup.8, R.sup.9 and R.sup.10 must have a Hammett .sigma..sub..rho.
value (Hansch et al., Chem. Rev. 1991, 91, 165) greater than 0.2
(i.e. at least one of these substituents needs to be a sufficiently
electron withdrawing group, (e.g. CF.sub.3, Br, etc.)). In the
process according to the present invention all R.sup.3, R.sup.4,
R.sup.5, R.sup.8, R.sup.9 and R.sup.10 are hydrocarbyl substituents
which have a Hammett value of less than 0.2. Further, the reference
fails to teach or suggest the molecular weight distribution of the
components in the resulting polymer may be altered or controlled by
altering or controlling the reaction conditions.
[0010] The present invention seeks to provide a relatively simple
method for controlling the ratio of the molecular weight
distribution of a bimodal resin and optionally the comonomer
placement or distribution in a bimodal resin produced in a single
gas or slurry phase reactor in the presence of a mixed catalyst
system on the same support by controlling one or more steps
selected from the group consisting of:
[0011] (a) altering the temperature of the reaction by at least
2.degree. C. within the range from 50 to 120.degree. C. in a gas
phase reactor and within the range from 20 to 150.degree. C. in a
slurry phase reactor;
[0012] (b) altering the partial pressure of the hydrogen component
of the reaction mixture by at least 0.02 psi (0.138 KPa);
[0013] (c) altering the partial pressure of one or more monomers in
the reaction mixture by not less than 10 psi (68.94 KPa); and
[0014] (d) altering the amount of non polymerizable hydrocarbon in
the reaction mixture in a gas phase by not less than 0.5 mole
%.
SUMMARY OF THE INVENTION
[0015] The present invention provides processes for controlling one
or more of the ratio of high molecular weight polymer to low
molecular weight polymer and comonomer incorporation, in
polymerization process selected from the group consisting of a
continuous fluidized bed gas phase polymerization at a temperature
from 50 to 120.degree. C. and a slurry polymerization in a single
reactor at a temperature from 20 to 150.degree. C. of a reaction
mixture comprising one or more of hydrogen, nitrogen, C.sub.1-7 non
polymerizable hydrocarbons, and C.sub.2-8 olefins polymerized in
the presence of a dual catalyst wherein both catalyst components
are on the same or different supports and the activity of each
catalyst has a different response to one or more of temperature,
partial pressure of hydrogen in the reaction mixture, partial
pressure of (co)monomers (e.g. ethylene) in the reaction mixture,
and the amount of inert hydrocarbons in the reaction mixture, which
comprises one or more steps selected from the group consisting
of:
[0016] (a) altering the temperature of the reaction by at least
2.degree. C. within the range from 50 to 120.degree. C. for a gas
phase polymerization and within the range from 20 to 150.degree. C.
for a slurry phase polymerization;
[0017] (b) altering the partial pressure of the hydrogen component
of the reaction mixture by at least 0.02 psi (0.138 KPa);
[0018] (c) altering the partial pressure of one or more monomers
(e.g. ethylene) in the reaction mixture by not less than 10 psi
(68.94 KPa); and
[0019] (d) altering the amount of non polymerizable hydrocarbon in
the gas phase reaction mixture by not less than 0.5 mole %.
[0020] The present invention further provides a dual catalyst
system suitable for producing a bimodal resin preferably having at
least one higher molecular weight (Mw) fraction having a greater
comonomer incorporation than that of a lower molecular weight (Mw)
fraction wherein:
[0021] (i) the first component of which comprises a catalyst of the
formula: ##STR1## wherein M is a group IV transition metal; R.sup.1
and R.sup.6 are independently selected from the group consisting of
a hydrogen atom, alkyl radicals having up to 15, carbon atoms, aryl
radicals having up to 25, carbon atoms, alkoxy radicals having up
to 15 carbon atoms, and amido radicals which are unsubstituted or
substituted by up to two alkyl radicals containing up to 15 carbon
atoms, R.sup.2 and R.sup.7 are independently selected from the
group consisting of alkyl radicals having up to 15 carbon atoms,
aryl radicals having up to 25 carbon atoms and silyl radicals of
the formula Si(R.sup.11).sub.3 wherein each R.sup.11 is
independently selected from the group consisting of alkyl radicals
having up to 15 carbon atoms, and aryl radicals having up to 25
carbon atoms; R.sup.3, R.sup.4, R.sup.5, R.sup.8, R.sup.9 and
R.sup.10 are independently selected from the group consisting of a
hydrogen atom, a heteroatom containing group having up to 20 carbon
atoms, and a hydrocarbon group containing up to 25 carbon atoms,
provided that none of these groups has a Hammett .sigma..sub..rho.
value greater than 0.20; X and X' are selected from the group
consisting of a halogen atom, alkyl radicals having up to 15 carbon
atoms, aryl radicals having up to 25 carbon atoms, alkoxy radicals
having up to 15 carbon atoms, amido radicals which are
unsubstituted or substituted by up to two alkyl radicals containing
up to 15 carbon atoms, and phenoxy radicals having up to 18 carbon
atoms;
[0022] (ii) the second component of which comprises a catalyst of
the formula: (L).sub.n-M--(Y).sub.p wherein M is selected from the
group consisting of Ti, Zr and Hf; L is a monoanionic ligand
independently selected from the group consisting of
cyclopentadienyl-type ligands, and a bulky heteroatom ligand
containing not less than five atoms in total (typically of which at
least 20%, preferably at least 25% numerically are carbon atoms)
and further containing at least one heteroatom selected from the
group consisting of boron, nitrogen, oxygen, phosphorus, sulfur and
silicon said bulky heteroatom ligand being sigma or pi-bonded to M,
Y is independently selected for the group consisting of activatable
ligands; n may be from 1 to 3; and p may be from 1 to 3, provided
that the sum of n+p equals the valence state of M, and further
provided that two L ligands may be bridged.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows the GPC profiles of the polymers produced in
Examples 1 and 2.
[0024] FIG. 2 shows the GPC profiles of the polymers produced in
Examples 3 and 4.
[0025] FIG. 3 shows the GPC profiles of the polymers produced in
Examples 4, 5 and 6.
[0026] FIG. 4 shows the GPC--FTIR profiles of the polymer produced
in Example 7.
[0027] FIG. 5 shows the GPC--FTIR profiles of the polymer produced
in Example 8.
[0028] FIG. 6 shows the GPC profiles of the polymers produced in
Examples 7 and 9.
DETAILED DESCRIPTION
[0029] As used in this specification the following words or phrases
have the following meanings:
[0030] Polydispersity is the ratio of the weight average molecular
weight (as determined by GPC) to the number average molecular
weight (as determined by GPC) (i.e. Mw/Mn) of any component in the
bimodal resin or the bimodal resin per se.
[0031] The term "cyclopentadienyl" refers to a 5-member carbon ring
having delocalized bonding within the ring and typically being
bound to the active catalyst site, generally a group 4 metal (M)
through .eta..sup.5-bonds.
[0032] The phrase mixed catalyst or dual catalyst or catalyst
system on a single support means that substantially both components
(e.g. at least about 90 weight %, preferably more than 98 weight %
of support contains both catalysts) are on the same support. The
catalyst components may be deposited either sequentially or
concurrently on the same support particles.
[0033] In another embodiment, the catalyst could be a blend of two
or more catalysts each of which happen to be on the same type of or
a similar or a different type of support (e.g. silica, alumina, and
polymeric supports). The different catalysts are supported on
different particles.
[0034] The gas phase polymerization of olefins and particularly
alpha olefins had been known for at least about 30 years. Generally
a gaseous mixture comprising from 0 to 15 mole % of hydrogen, from
0 to 30 mole % of one or more C.sub.3-8 alpha olefins, from 15 to
100 mole % of ethylene, and from 0 to 75 mole % of nitrogen and/or
a non-polymerizable hydrocarbon at a temperature from 50.degree. C.
to 120.degree. C., preferably from 60.degree. C. to 120.degree. C.,
most preferably from 75.degree. C. to about 110.degree. C., and at
pressures typically not exceeding 3,500 KPa (about 500 psi),
preferably not greater than 2,400 KPa (about 350 psi) are
polymerized in the presence of a mixed catalyst system on a single
support in a single reactor.
[0035] Slurry polymerization is well known in the art. The
polymerization is conducted in an inert diluent in which the
resulting polymer is not soluble. The monomers may be soluble in
the diluent. The diluent is typically a hydrocarbyl compound such
as a C.sub.5-12 hydrocarbon which may be unsubstituted or
substituted by a C.sub.1-4 alkyl radical. Preferably the diluent is
unsubstituted. Some potential diluents include pentane, hexane,
heptane, octane, cyclohexane and methylcyclohexane. The diluent may
be hydrogenated naphtha. The diluent may also be a C.sub.8-12
aromatic hydrocarbon such as that sold by Exxon Chemical Company
under the trademark ISOPAR.RTM. E.
[0036] Generally the monomers are dispersed or dissolved in the
diluent. The reaction takes place at temperatures from about
20.degree. C. to about 120.degree. C., preferably from about
40.degree. C. to 100.degree. C., desirably from 50.degree. C. to
95.degree. C. The pressure in the reactor may be from about 15 psi
to about 4,500 psi, preferably from about 100 to 1,500 psi. The
reactors may be "loop" reactors with a settling leg to remove
polymer.
[0037] Suitable olefin monomers may be ethylene and C.sub.3-20
mono- and di-olefins. Preferred monomers include ethylene and
C.sub.3-8 alpha olefins which are unsubstituted or substituted by
up to two C.sub.1-6 alkyl radicals. Illustrative non-limiting
examples of such alpha olefins are one or more of propylene,
1-butene, 1-hexene and 1-octene.
[0038] The polyethylene polymers which may be prepared in
accordance with the present invention typically comprise not less
than 60, preferably not less than 70, most preferably not less than
80 weight % of ethylene and the balance of one or more C.sub.3-8
alpha olefins, preferably selected from the group consisting of
1-butene, 1-hexene and 1-octene.
[0039] The polymers prepared in accordance with the present
invention have a bimodal or multimodal molecular weight
distribution. Overall, the weight average molecular weight (Mw)
will preferably be greater than about 30,000 ranging up to
10.sup.7, preferably 10.sup.5 to 5.times.10.sup.5. Typically the
polymer will have a density greater than 0.89 g/cc, preferably
greater than 0.910 g/cc, typically in the range from 0.915 to 0.960
g/cc. There will be a lower molecular weight component seen as a
peak or shoulder on a GPC analysis and there will be one or more
higher molecular weight components also seen as a separate peak or
shoulder on a GPC analysis. Generally the lower molecular weight
component will be present in an amount from 10 to 90, preferably
from 30 to 70, most preferably from 35 to 65 weight % of the total
bimodal resin. The high molecular weight component may be present
in amounts from 90 to 10, preferably 70 to 30, most preferably from
about 65 to 35 weight % of the total polymer.
[0040] The low molecular weight polyethylene component may have a
weight average molecular weight greater than 5,000, typically from
10,000 to 140,000, preferably from about 15,000 to about 100,000,
most preferably from about 20,000 to 100,000 as estimated by
deconvolution of a GPC curve. The low molecular weight polyethylene
may have a polydispersity (Mw/Mn) greater than about 3, typically
from 3 to 15, preferably from about 5 to 12.
[0041] The high molecular weight polyethylene component may have a
weight average molecular weight greater than 200,000, typically
from 250,000 to 800,000 as determined by deconvolution of a GPC
plot. The high molecular weight polyethylene may have a
polydispersity (Mw/Mn) less than about 10, typically from 2 to
8.
[0042] The resins of the present invention are suitable for use in
a number of applications including film (blown and cast), extruded
articles such as pipe (for potable water or for gas), rotomolded
articles, injection molded articles and blow molded articles.
[0043] The catalyst system of the present invention may be
supported on an inorganic or refractory support, including for
example alumina, silica and clays or modified clays or an organic
support (including polymeric support such as polystyrene or
cross-linked polystyrene). The catalyst support may be a
combination of the above components. However, preferably both
catalyst components are supported on the same inorganic support or
an organic support (e.g. polymeric) or mixed support. Some
refractories include silica which may be treated to reduce surface
hydroxyl groups and alumina. The support or carrier may be a
spray-dried silica. Generally the support will have an average
particle size from about 0.1 to about 1,000, preferably from about
10 to 150 microns. The support typically will have a surface area
of at least about 10 m.sup.2/g, preferably from about 150 to 1,500
m.sup.2/g. The pore volume of the support should be at least 0.2,
preferably from about 0.3 to 5.0 ml/g.
[0044] Generally the refractory or inorganic support may be heated
at a temperature of at least 200.degree. C. for up to 24 hours,
typically at a temperature from 500.degree. C. to 800.degree. C.
for about 2 to 20, preferably 4 to 10 hours. The resulting support
will be essentially free of adsorbed water (e.g. less than about 1
weight %) and may have a surface hydroxyl content from about 0.1 to
5 mmol/g of support, preferably from 0.5 to 3 mmol/g.
[0045] A silica suitable for use in the present invention has a
high surface area and is amorphous. For example, commercially
available silicas are marketed under the trademark of Sylopol.RTM.
958 and 955 by the Davison Catalysts, a Division of W.R. Grace, and
Company and ES-70W by Ineos Silica.
[0046] The amount of the hydroxyl groups in silica may be
determined according to the method disclosed by J. B. Peri and A.
L. Hensley, Jr., in J. Phys. Chem., 72 (8), 2926, 1968, the entire
contents of which are incorporated herein by reference.
[0047] While heating is the most preferred means of removing OH
groups inherently present in many carriers, such as silica, the OH
groups may also be removed by other removal means, such as chemical
means. For example, a desired proportion of OH groups may be
reacted with a suitable chemical agent, such as a hydroxyl reactive
aluminum compound (e.g. triethyl aluminum) or a silane compound.
This method of treatment has been disclosed in the literature and
two relevant examples are: U.S. Pat. No. 4,719,193 to Levine in
1988 and by Noshay A. and Karol F. J. in Transition Metal Catalyzed
Polymerizations, Ed. R. Quirk, 396, 1989. For example the support
may be treated with an aluminum compound of the formula
Al((O).sub.aR.sup.1).sub.bX.sub.3-b wherein a is either 0 or 1, b
is an integer from 0 to 3, R.sup.1 is a C.sub.1-8 alkyl radical,
and X is a chlorine atom. The amount of aluminum compound is such
that the amount of aluminum on the support prior to adding the
remaining catalyst components will be from about 0 to 2.5 weight %,
preferably from 0 to 2.0 weight % based on the weight of the
support.
[0048] The clay type supports are also preferably treated to reduce
adsorbed water and surface hydroxyl groups. However, the clays may
be further subject to an ion exchange process which may tend to
increase the separation or distance between the adjacent layers of
the clay structure.
[0049] The polymeric support may be cross linked polystyrene
containing up to about 50 weight %, preferably not more than 25
weight %, most preferably less than 10 weight % of a cross linking
agent such as divinyl benzene.
[0050] In accordance with one embodiment of the present invention
the two catalysts may be deposited on the same support (i.e.
preferably both catalysts should be on each particle of support).
The catalysts may be used in a broad molar ratio to achieve the
required molecular weight distribution. For example the catalysts
could be used in a molar ratio of the active transition metal of
the first catalyst to the second catalyst from 95:5 to 5:95,
typically 80:20 to 20:80 generally from 60:40 to 40:60.
[0051] In accordance with the present invention the first catalyst
comprises a catalyst of the formula I: ##STR2## wherein M is a
group 4 transition metal, preferably Zr or Ti; R.sup.1 and R.sup.6
are independently selected from the group consisting of C.sub.1-6
alkyl or C.sub.6-10 aryl radicals, preferably cyclohexyl radicals;
R.sup.2 and R.sup.7 are independently selected from the group
consisting of C.sub.3-5 secondary or tertiary alkyl radicals,
preferably t-butyl radicals; R.sup.3, R.sup.4, R.sup.5, R.sup.8,
R.sup.9 and R.sup.10 are independently selected from the group
consisting of a hydrogen atom, C.sub.1-4 alkyl radicals, C.sub.6-10
aryl radicals, C.sub.1-C.sub.4 alkoxy radicals, which substituents
have a Hammett .sigma..sub..rho. value of less than 0.2; and X and
X' are selected from the group consisting of a halogen atom,
C.sub.1-4 alkyl radicals, C.sub.7-12 arylalkyl radicals, C.sub.6-10
phenoxy radicals, amido radicals which may be substituted by up to
two C.sub.1-4 alkyl radicals and C.sub.1-4 alkoxy radicals;
preferably, a chlorine atom, a methyl radical, an ethyl radical and
a benzyl radical.
[0052] In the first catalyst (first component) preferably R.sup.4
and R.sup.9 are selected from the group consisting of a
C.sub.1-C.sub.4 alkoxy radical, most preferably methoxy radicals
and R.sup.3, R.sup.5, R.sup.8 and R.sup.10 are hydrogen.
[0053] As noted above none of R.sup.3, R.sup.4, R.sup.5, R.sup.8,
R.sup.9 and R.sup.10 has a Hammett .sigma..sub..rho. value (Hansch
et al., Chem. Rev. 1991, 91, 165) greater than 0.2.
[0054] The synthesis of desired ligands of the first catalyst can
be accomplished by reaction of salicylaldehydes with amines.
Preparation of the requisite salicylaldehydes can be accomplished
using standard synthetic techniques.
[0055] Metallation of the ligands can be accomplished by reaction
with basic reagents for example Zr(CH.sub.2Ph).sub.4. Reaction of
the ligands with Zr(CH.sub.2Ph).sub.4 occurs with elimination of
toluene. Alternately, ligands can be deprotonated with reagents
such as BuLi, KH or Na metal and then reacted with metal halides,
for example ZrCl.sub.4.
[0056] The second component of the catalyst system (second
catalyst) is a bulky ligand single site catalyst of the formula II:
(L).sub.n-M--(Y).sub.p wherein M is selected from the group
consisting of Ti, Zr and Hf; L is a monoanionic ligand
independently selected from the group consisting of
cyclopentadienyl-type ligands, and a bulky heteroatom ligand
containing not less than five atoms in total (typically of which at
least 20%, preferably at least 25% numerically are carbon atoms)
and further containing at least one heteroatom selected from the
group consisting of boron, nitrogen, oxygen, phosphorus, sulfur and
silicon said bulky heteroatom ligand being sigma or pi-bonded to M;
Y is independently selected from the group consisting of
activatable ligands; n may be from 1 to 3; and p may be from 1 to
3, provided that the sum of n+p equals the valence state of M, and
further provided that two L ligands may be bridged.
[0057] Non-limiting examples of bridging group include bridging
groups containing at least one Group 13 to 16 atom, often referred
to a divalent moiety such as but not limited to at least one of a
carbon, oxygen, nitrogen, silicon, boron, germanium and tin atom or
a combination thereof. Preferably, the bridging group contains a
carbon, silicon or germanium atom, most preferably at least one
silicon atom or at least one carbon atom. The bridging group may
also contain substituent radicals as defined above including
halogens.
[0058] Some bridging groups include but are not limited to, a di
C.sub.1-6 alkyl radical (e.g. alkylene radical for example an
ethylene bridge), di C.sub.6-10 aryl radical (e.g. a benzyl radical
having two bonding positions available), silicon or germanium
radicals substituted by one or more radicals selected from the
group consisting of C.sub.1-6 alkyl, C.sub.6-10 aryl, phosphine or
amine radical which are unsubstituted or up to fully substituted by
one or more C.sub.1-6 alkyl or C.sub.6-10 aryl radicals, or a
hydrocarbyl radical such as a C.sub.1-6 alkyl radical or a
C.sub.6-10 arylene (e.g. divalent aryl radicals); divalent
C.sub.1-6 alkoxide radicals (e.g. --CH.sub.2 CHOH CH.sub.2--) and
the like.
[0059] Exemplary of the silyl species of bridging groups are
dimethylsilyl, methylphenylsilyl, diethylsilyl, ethylphenylsilyl,
diphenylsilyl bridged compounds. Most preferred of the bridged
species are dimethylsilyl, diethylsilyl and methylphenylsilyl
bridged compounds.
[0060] Exemplary hydrocarbyl radicals for bridging groups include
methylene, ethylene, propylene, butylene, phenylene and the like,
with methylene being preferred.
[0061] Exemplary bridging amides include dimethylamide,
diethylamide, methylethylamide, di-t-butylamide, diisopropylamide
and the like.
[0062] The term "cyclopentadienyl" refers to a 5-member carbon ring
having delocalized bonding within the ring and typically being
bound to the active catalyst site, generally a group 4 metal (M)
through .eta..sup.5-bonds. The cyclopentadienyl ligand may be
unsubstituted or up to fully substituted with one or more
substituents selected from the group consisting of C.sub.1-10
hydrocarbyl radicals in which hydrocarbyl substituents are
unsubstituted or further substituted by one or more substituents
selected from the group consisting of a halogen atom and a
C.sub.1-4 alkyl radical; a halogen atom; a C.sub.1-8 alkoxy
radical; a C.sub.6-10 aryl or aryloxy radical; an amido radical
which is unsubstituted or substituted by up to two C.sub.1-8 alkyl
radicals; a phosphido radical which is unsubstituted or substituted
by up to two C.sub.1-8 alkyl radicals; silyl radicals of the
formula --Si--(R).sub.3 wherein each R is independently selected
from the group consisting of hydrogen, a C.sub.1-8 alkyl or alkoxy
radical, and C.sub.6-10 aryl or aryloxy radicals; and germanyl
radicals of the formula Ge--(R).sub.3 wherein R is as defined
above.
[0063] Typically the cyclopentadienyl-type ligand is selected from
the group consisting of a cyclopentadienyl radical, an indenyl
radical and a fluorenyl radical where the radicals are
unsubstituted or up to fully substituted by one or more
substituents selected from the group consisting of a fluorine atom,
a chlorine atom; C.sub.1-4 alkyl radicals; and a phenyl or benzyl
radical which is unsubstituted or substituted by one or more
fluorine atoms.
[0064] In the formula above if none of the L ligands is bulky
heteroatom ligand then the catalyst could be a mono
cyclopentadienyl (Cp) catalyst, a bridged bis Cp catalyst (a
traditional metallocene) or a bridged constrained geometry type
catalyst or a tris Cp catalyst.
[0065] If the second catalyst component contains one or more bulky
heteroatom ligands the catalyst would have the formula: ##STR3##
wherein M is a transition metal selected from the group consisting
of Ti, Hf and Zr; D is independently a bulky heteroatom ligand (as
described below); L is a monoanionic ligand selected from the group
consisting of cyclopentadienyl-type ligands; Y is independently
selected from the group consisting of activatable ligands; m is 1
or 2; n is 0 or 1; and p is an integer and the sum of m+n+p equals
the valence state of M, provided that when m is 2, D may be the
same or different bulky heteroatom ligands.
[0066] For example, the catalyst may be a bis(phosphinimine), or a
mixed phosphinimine ketimide dichloride complex of titanium,
zirconium or hafnium. Alternately, the catalyst could contain one
phosphinimine ligand or one ketimide ligand, one "L" ligand (which
is most preferably a cyclopentadienyl-type ligand) and two "Y"
ligands (which are preferably both chloride).
[0067] The preferred metals (M) are from Group 4 (especially
titanium, hafnium or zirconium) with titanium being most preferred.
In one embodiment the catalysts are group 4 metal complexes in the
highest oxidation state.
[0068] Bulky heteroatom ligands (D) include but are not limited to
phosphinimine ligands and ketimide (ketimine) ligands.
[0069] In a further embodiment, the catalyst may contain one or two
phosphinimine ligands (PI) which are bonded to the metal and the
second catalyst has the formula: ##STR4## wherein M is a group 4
metal; PI is a phosphinimine ligand; L is a monoanionic ligand
selected from the group consisting of a cyclopentadienyl-type
ligand; Y is independently selected from the group consisting of
activatable ligands; m is 1 or 2; n is 0 or 1; p is an integer and
the sum of m+n+p equals the valence state of M.
[0070] The phosphinimine ligand is defined by the formula: ##STR5##
wherein each R.sup.21 is independently selected from the group
consisting of a hydrogen atom; a halogen atom; C.sub.1-20,
preferably C.sub.1-10 hydrocarbyl radicals which are unsubstituted
by or further substituted by a halogen atom; a C.sub.1-8 alkoxy
radical; a C.sub.6-10 aryl or aryloxy radical; an amido radical; a
silyl radical of the formula: --Si--(R.sup.22).sub.3 wherein each
R.sup.22 is independently selected from the group consisting of
hydrogen, a C.sub.1-8 alkyl or alkoxy radical, and C.sub.6-10 aryl
or aryloxy radicals; and a germanyl radical of the formula:
--Ge--(R.sup.22).sub.3 wherein R.sup.22 is as defined above.
[0071] The preferred phosphinimines are those in which each
R.sup.21 is a hydrocarbyl radical, preferably a C.sub.1-6
hydrocarbyl radical.
[0072] Suitable phosphinimine catalysts are Group 4 organometallic
complexes which contain one phosphinimine ligand (as described
above) and one ligand L which is either a cyclopentadienyl-type
ligand or a heteroatom ligand.
[0073] As used herein, the term "ketimide ligand" refers to a
ligand which:
[0074] (a) is bonded to the transition metal via a metal-nitrogen
atom bond;
[0075] (b) has a single substituent on the nitrogen atom (where
this single substituent is a carbon atom which is doubly bonded to
the N atom); and
[0076] (c) has two substituents Sub 1 and Sub 2 (described below)
which are bonded to the carbon atom.
[0077] Conditions a, b and c are illustrated below: ##STR6##
[0078] The substituents "Sub 1" and "Sub 2" may be the same or
different. Exemplary substituents include hydrocarbyls having from
1 to 20, preferably from 3 to 6, carbon atoms, silyl groups (as
described below), amido groups (as described below) and phosphido
groups (as described below). For reasons of cost and convenience it
is preferred that these substituents both be hydrocarbyls,
especially simple alkyls and most preferably tertiary butyl. "Sub
1" and "Sub 2" may be the same or different and can be bonded to
each other to form a ring.
[0079] Suitable ketimide catalysts are Group 4 organometallic
complexes which contain one ketimide ligand (as described above)
and one ligand L which is either a cyclopentadienyl-type ligand or
a heteroatom ligand.
[0080] The term bulky heteroatom ligand (D) is not limited to
phosphinimine or ketimide ligands and includes ligands which
contain at least one heteroatom selected from the group consisting
of boron, nitrogen, oxygen, phosphorus, sulfur and silicon. The
heteroatom ligand may be sigma or pi-bonded to the metal. Exemplary
heteroatom ligands include silicon-containing heteroatom ligands,
amido ligands, alkoxy ligands, boron heterocyclic ligands and
phosphole ligands, as all described below.
[0081] Silicon containing heteroatom ligands are defined by the
formula: (Y)SiR.sub.xR.sub.yR.sub.z wherein the--denotes a bond to
the transition metal and Y is sulfur or oxygen.
[0082] The substituents on the Si atom, namely R.sub.x, R.sub.y and
R.sub.z are required in order to satisfy the bonding orbital of the
Si atom. The use of any particular substituent R.sub.x, R.sub.y or
R.sub.z is not especially important to the success of this
invention. It is preferred that each of R.sub.x, R.sub.y and
R.sub.z is a C.sub.1-2 hydrocarbyl group (i.e. methyl or ethyl)
simply because such materials are readily synthesized from
commercially available materials.
[0083] The term "amido" is meant to convey its broad, conventional
meaning. Thus, these ligands are characterized by (a) a
metal-nitrogen bond; and (b) the presence of two substituents
(which are typically simple alkyl or silyl groups) on the nitrogen
atom.
[0084] The terms "alkoxy" and "aryloxy" is also intended to convey
its conventional meaning. Thus, these ligands are characterized by
(a) a metal oxygen bond; and (b) the presence of a hydrocarbyl
group bonded to the oxygen atom. The hydrocarbyl group may be a
C.sub.1-10 straight chained, branched or cyclic alkyl radical or a
C.sub.6-13 aromatic radical where the radicals are unsubstituted or
further substituted by one or more C.sub.1-4 alkyl radicals (e.g.
2,6 di-tertiary butyl phenoxy).
[0085] Boron heterocyclic ligands are characterized by the presence
of a boron atom in a closed ring ligand. This definition includes
heterocyclic ligands which also contain a nitrogen atom in the
ring. These ligands are well known to those skilled in the art of
olefin polymerization and are fully described in the literature
(see, for example, U.S. Pat. Nos. 5,637,659; 5,554,775; and the
references cited therein).
[0086] The term "phosphole" is also meant to convey its
conventional meaning. "Phospholes" are cyclic dienyl structures
having four carbon atoms and one phosphorus atom in the closed
ring. The simplest phosphole is C.sub.4H.sub.4 (which is analogous
to cyclopentadiene with one carbon in the ring being replaced by
phosphorus). The phosphole ligands may be substituted with, for
example, C.sub.1-20 hydrocarbyl radicals (which may, optionally,
contain halogen substituents); phosphido radicals; amido radicals;
or silyl or alkoxy radicals. Phosphole ligands are also well known
to those skilled in the art of olefin polymerization and are
described as such in U.S. Pat. No. 5,434,116 (Sone, to Tosoh).
[0087] In one embodiment the second catalyst may contain no
phosphinimine ligands as the bulky heteroatom ligand. The bulky
heteroatom containing ligand may be selected from the group
consisting of ketimide ligands, silicon-containing heteroatom
ligands, amido ligands, alkoxy ligands, boron heterocyclic ligands
and phosphole ligands. In such catalysts the Cp ligand may be
present or absent.
[0088] The preferred metals (M) are from Group 4 (especially
titanium, hafnium or zirconium), with titanium being most
preferred.
[0089] The catalyst systems (e.g. first and second catalyst) in
accordance with the present invention may be activated with an
activator selected from the group consisting of:
[0090] (i) a complex aluminum compound of the formula
R.sup.12.sub.2AlO(R.sup.12AlO).sub.mAlR.sup.12.sub.2 wherein each
R.sup.12 is independently selected from the group consisting of
C.sub.1-20 hydrocarbyl radicals and m is from 3 to 50, and
optionally a hindered phenol to provide a molar ratio of
Al:hindered phenol from 2:1 to 5:1 if the hindered phenol is
present;
[0091] (ii) ionic activators selected from the group consisting of:
[0092] (A) compounds of the formula
[R.sup.13].sup.+[B(R.sup.14).sub.4].sup.- wherein B is a boron
atom, R.sup.13 is a cyclic C.sub.5-7 aromatic cation or a triphenyl
methyl cation and each R.sup.14 is independently selected from the
group consisting of phenyl radicals which are unsubstituted or
substituted with a hydroxyl group or with 3 to 5 substituents
selected from the group consisting of a fluorine atom, a C.sub.1-4
alkyl or alkoxy radical which is unsubstituted or substituted by a
fluorine atom; and a silyl radical of the formula
--Si--(R.sup.15).sub.3; wherein each R.sup.15 is independently
selected from the group consisting of a hydrogen atom and a
C.sub.1-4 alkyl radical; and [0093] (B) compounds of the formula
[(R.sup.18).sub.t ZH].sup.+[B(R.sup.14).sub.4].sup.- wherein B is a
boron atom, H is a hydrogen atom, Z is a nitrogen atom or
phosphorus atom, t is 2 or 3 and R.sup.18 is independently selected
from the group consisting of C.sub.1-18 alkyl radicals, a phenyl
radical which is unsubstituted or substituted by up to three
C.sub.1-4 alkyl radicals, or one R.sup.18 taken together with the
nitrogen atom may form an anilinium radical and R.sup.14 is as
defined above; and [0094] (C) compounds of the formula
B(R.sup.14).sub.3 wherein R.sup.14 is as defined above; and
[0095] (iii) mixtures of (i) and (ii).
[0096] Preferably the activator is a complex aluminum compound of
the formula R.sup.12.sub.2AlO(R.sup.12AlO).sub.mAlR.sup.12.sub.2
wherein each R.sup.12 is independently selected from the group
consisting of C.sub.1-20 hydrocarbyl radicals and m is from 3 to
50, and optionally a hindered phenol to provide a molar ratio of
Al:hindered phenol from 2:1 to 5:1 if the hindered phenol is
present. In the aluminum compound preferably, R.sup.12 is methyl
radical and m is from 10 to 40. The preferred molar ratio of
Al:hindered phenol, if it is present, is from 3.25:1 to 4.50:1.
Preferably the phenol is substituted in the 2, 4 and 6 position by
a C.sub.2-6 alkyl radical. Desirably the hindered phenol is
2,6-di-tert-butyl-4-ethyl-phenol.
[0097] The aluminum compounds (alumoxanes and optionally hindered
phenol) are typically used as activators in substantial molar
excess compared to the amount of metal in the catalyst.
Aluminum:transition metal molar ratios of from 10:1 to 10,000:1 are
preferred, most preferably 10:1 to 500:1 especially from 40:1 to
120:1.
[0098] Ionic activators are well known to those skilled in the art.
The "ionic activator" may abstract one activatable ligand so as to
ionize the catalyst center into a cation, but not to covalently
bond with the catalyst and to provide sufficient distance between
the catalyst and the ionizing activator to permit a polymerizable
olefin to enter the resulting active site.
[0099] Examples of ionic activators include: [0100]
triethylammonium tetra(phenyl)boron, [0101] tripropylammonium
tetra(phenyl)boron, [0102] tri(n-butyl)ammonium tetra(phenyl)boron,
[0103] trimethylammonium tetra(p-tolyl)boron, [0104]
trimethylammonium tetra(o-tolyl)boron, [0105] tributylammonium
tetra(pentafluorophenyl)boron, [0106] tripropylammonium
tetra(o,p-dimethylphenyl)boron, [0107] tributylammonium
tetra(m,m-dimethylphenyl)boron, [0108] tributylammonium
tetra(p-trifluoromethylphenyl)boron, [0109] tributylammonium
tetra(pentafluorophenyl)boron, [0110] tri(n-butyl)ammonium
tetra(o-tolyl)boron, [0111] N,N-dimethylanilinium
tetra(phenyl)boron, [0112] N,N-diethylanilinium tetra(phenyl)boron,
[0113] N,N-diethylanilinium tetra(phenyl)n-butylboron, [0114]
di-(isopropyl)ammonium tetra(pentafluorophenyl)boron, [0115]
dicyclohexylammonium tetra(phenyl)boron, [0116]
triphenylphosphonium tetra(phenyl)boron, [0117]
tri(methylphenyl)phosphonium tetra(phenyl)boron, [0118]
tri(dimethylphenyl)phosphonium tetra(phenyl)boron, [0119]
tropillium tetrakispentafluorophenyl borate, [0120]
triphenylmethylium tetrakispentafluorophenyl borate, [0121]
tropillium phenyltrispentafluorophenyl borate, [0122]
triphenylmethylium phenyltrispentafluorophenyl borate, [0123]
benzene (diazonium) phenyltrispentafluorophenyl borate, [0124]
tropillium tetrakis (2,3,5,6-tetrafluorophenyl)borate, [0125]
triphenylmethylium tetrakis (2,3,5,6-tetrafluorophenyl)borate,
[0126] tropillium tetrakis (3,4,5-trifluorophenyl)borate, [0127]
benzene (diazonium) tetrakis (3,4,5-trifluorophenyl)borate, [0128]
tropillium tetrakis (1,2,2-trifluoroethenyl)borate, [0129]
triphenylmethylium tetrakis (1,2,2-trifluoroethenyl)borate, [0130]
tropillium tetrakis (2,3,4,5-tetrafluorophenyl)borate, and [0131]
triphenylmethylium tetrakis (2,3,4,5-tetrafluorophenyl)borate.
[0132] Readily commercially available ionic activators include:
[0133] N,N-dimethylaniliniumtetrakispentafluorophenyl borate;
[0134] triphenylmethylium tetrakispentafluorophenyl borate
(tritylborate); and [0135] trispentafluorophenyl borane.
[0136] Ionic activators may also have an anion containing at least
one group comprising an active hydrogen or at least one of any
substituent able to react with the support. As a result of these
reactive substituents, the ionic portion of these ionic activators
may become bonded to the support under suitable conditions. One
non-limiting example includes ionic activators with tris
(pentafluorophenyl) (4-hydroxyphenyl)borate as the anion. These
tethered ionic activators are more fully described in U.S. Pat.
Nos. 5,834,393; 5,783,512; and 6,087,293.
[0137] Suitable linking substituents, E, on compatible anions used
with unmodified inorganic oxides or with inorganic oxide containing
only residual hydroxyl functionality, include moieties bearing
silane, siloxane, hydrocarbyloxysilane, halosilane, amino,
carboxylic acid, carboxylic acid ester, aldehyde, ketone or epoxide
functionality, containing from 1 to 1.times.10.sup.6 non-hydrogen
atoms, more preferably from 2 to 1,000 non-hydrogen atoms, and most
preferably 4 to 20 non-hydrogen atoms. In practice, use of silane
containing compatible anions may require use of a base catalyst,
such as a tri(C.sub.1-4 alkyl)amine, to effect the reaction with a
substrate containing only residual hydroxyl functionality.
Preferably E for use with such unmodified inorganic oxide compounds
is a silane or chlorosilane substituted hydrocarbyl radical.
Preferred linking substituents, E, include silyl-substituted aryl,
silyl-substituted aralkyl, silyl-substituted alkaryl,
silyl-substituted alkyl, silyl-substituted haloaryl, or
silyl-substituted haloalkyl groups, including polymeric linking
groups, most preferably p-silylphenyl (--C.sub.6H.sub.4 SiH.sub.3),
p-silyltetrafluorophenyl (--C.sub.6F.sub.4 SiH.sub.3),
silylnaphthyl (--C.sub.10H.sub.8 SiH.sub.3), silylperfluoronaphthyl
(--C.sub.10F.sub.8 SiH.sub.3), and 2-silyl-1-ethyl
(--C.sub.2H.sub.4 SiH.sub.3), groups.
[0138] Suitable linking substituents, E, on compatible anions used
with inorganic oxides that have been modified with reactive silane
functionality include moieties bearing silane, siloxane,
hydrocarbyloxysilane, halosilane, hydroxyl, thiol, amino,
carboxylic acid, carboxylic acid ester, aldehyde, ketone or epoxide
functionality containing from 1 to 1.times.10.sup.6 non-hydrogen
atoms, more preferably from 2 to 1,000 non-hydrogen atoms, and most
preferably 4 to 20 non-hydrogen atoms. Preferably E, in such
circumstances is a hydroxyl substituted hydrocarbyl radical, more
preferably a hydroxy-substituted aryl, hydroxy-substituted aralkyl,
hydroxy-substituted alkaryl, hydroxy-substituted alkyl,
hydroxy-substituted haloaryl, or hydroxy-substituted haloalkyl
group including polymeric linking groups, most preferably
hydroxyphenyl, hydroxytolyl, hydroxybenzyl, hydroxynaphthyl,
hydroxybisphenyl, hydroxycyclohexyl, C.sub.1-4 hydroxyalkyl, and
hydroxy-polystyryl groups, or fluorinated derivatives thereof. A
most preferred linking substituent, E, is a p-hydroxyphenyl,
4-hydroxybenzyl, 6-hydroxy-2-naphthyl group,
4-(4'-hydroxyphenyl)phenyl,
4-((4'-hydroxyphenyl)dimethylmethylene)phenyl, or fluorinated
derivatives thereof. A base catalyst, such as a tri(C.sub.1-4
alkyl)amine, may also be used to assist in the reaction with the
substrate.
[0139] Most highly preferably, E is one of the foregoing hydroxy
substituted substituents used in combination with a reactive silane
functionalized silica.
[0140] The ionic activators may be used in amounts to provide a
molar ratio of transition metal to boron will be from 1:1 to 1:6,
preferably from 1:1 to 1:2.
[0141] As noted above, the reaction mixture in a gas phase process
typically comprises from 0 to 15 mole % of hydrogen, from 0 to 30
mole % of one or more C.sub.3-8 alpha-olefins, from 15 to 100 mole
% of ethylene, and from 0 to 75 mole % of one or more non-reactive
gases. The non-reactive gases may be selected from the group
consisting of nitrogen and a C.sub.1-7 non-polymerizable
hydrocarbon such as an alkane (e.g. butane, isopentane and the
like).
[0142] In accordance with the present invention applicants have
found that it is possible to control the molecular weight
distribution of a bimodal resin (e.g. the ratio of the high
molecular weight fraction to the low molecular weight fraction) and
optionally the comonomer placement or distribution in a bimodal
resin produced in a single gas or slurry phase reactor in the
presence of a mixed catalyst system on the same or different
supports by controlling one or more steps selected from the group
consisting of:
[0143] (a) altering the temperature of the reaction by at least
2.degree. C. within the range from 50 to 120.degree. C. for a gas
phase polymerization and within the range from 20 to 150.degree. C.
for a slurry phase polymerization;
[0144] (b) altering the partial pressure of the hydrogen component
of the reaction mixture by at least 0.02 psi (0.138 KPa);
[0145] (c) altering the partial pressure of one or more monomers
(e.g. ethylene) in the reaction mixture by not less than 10 psi
(68.94 KPa); and
[0146] (d) altering the amount of non polymerizable hydrocarbon in
the gas phase reaction mixture by not less than 0.5 mole %.
[0147] The reaction may take place in a single gas phase or slurry
phase reactor. The product is removed from the reactor by
conventional means and degassed and further treated.
[0148] The resulting resin may typically be compounded either by
the manufacturer or the converter (e.g. the company converting the
resin pellets into the final product). The blend may contain
fillers, pigments and other additives. Typically the fillers are
inert additives such as clay, talc, TiO.sub.2 and calcium carbonate
which may be added to the polyolefin in amounts from 0 weight % up
to about 50 weight %, preferably less than 30 weight %. The resin
may contain typical amounts of antioxidants and heat and light
stabilizers such as combinations of hindered phenols and one or
more of phosphates, phosphites and phosphonites typically in
amounts of less than 0.5 weight % based on the weight of the resin.
Pigments such as carbon black may also be added to the resin in
small amounts.
[0149] In the manufacture of pipe and other products, the
polyethylene resin blend may contain a nucleating agent in amounts
from about 1,500 to about 10,000 parts per million (ppm) based on
the weight of the polyolefin. Preferably the nucleating agent is
used in amounts from 2,000 to 8,000 ppm, most preferably from 2,000
to 5,000 ppm based on the weight of the polyolefin.
[0150] The nucleating agent may be selected from the group
consisting of dibenzylidene sorbitol, di(p-methyl benzylidene)
sorbitol, di(o-methyl benzylidene) sorbitol, di(p-ethylbenzylidene)
sorbitol, bis(3,4-dimethyl benzylidene) sorbitol,
bis(3,4-diethylbenzylidene) sorbitol and bis(trimethylbenzylidene)
sorbitol. One commercially available nucleating agent is
bis(3,4-dimethyl benzylidene) sorbitol.
[0151] The polymers made by the process of the present invention
are useful in conventional applications for polyolefins including
films, both blown and cast, injection molding, blow molding and
rotomolding.
[0152] For pipe applications desirably the polymer should have the
following characteristics:
[0153] ASTM D638 tensile stress at yield equal or greater than 23
MPa.
[0154] ASTM F2231-02: Charpy Impact test energy >0.6 J (With
this property, the material should exhibit excellent Rapid Crack
Propagation (RCP) resistance if tested according to ISO RCP tests
13477 (S4 RCP test) and 13478 (Full Scale RCP test).).
[0155] ASTM F1473 (Slow Crack Growth resistance test) PENT test at
2.4 MPa at 80.degree. C.>1,000 hours.
Hydrostatic Properties:
[0156] ASTM D2837: HDB (Hydrostatic Design Basis) at 23.degree.
C.1600 psi, and meet the 50-years substantiation requirement
according to PPI (Plastic Pipe Institute) TR-3 2004.
[0157] ASTM D2837: HDB (Hydrostatic Design Basis) at 60.degree. C.
1,000 psi.
[0158] ASTM D1598: no ductile and brittle failure at greater than
7,000 hours at both test conditions of hoop stress 740
psi/temperature 80.degree. C., and hoop stress 690 psi/temperature
90.degree. C. hydrostatic test at hoop.
[0159] With these hydrostatic test results, the material would meet
the PE100 requirements if it was tested according to the ISO
standards ISO 12162 and ISO 9080.
[0160] The polymer could have an I.sub.21/I.sub.5 from about 7 to
35.
[0161] Processability: The material should possesses excellent melt
strength for production of large diameter pipes of 12 inches or
larger without sagging of the melt as it exits the die.
[0162] The polymer should have a melt strength of 10cN determined
using a Rosand Capillary Rheometer.
Test Conditions:
[0163] Barrel Temperature: 230.degree. C.
[0164] Die: 2-mm Diameter, L/D=20
[0165] Pressure Transducer: 10,000 psi (68.95 MPa)
[0166] Piston Speed: 5.33 mm/min
[0167] Haul-off Angle: 52.degree.
[0168] Haul-off incremental speed: 500 m/(min).sup.2
[0169] For film products the polymer should have the following
properties as determined by the appropriate ASTM test method.
[0170] I.sub.21 less than 25, typically from 5 to 20, preferably
from 8 to 15 dg/min.
[0171] MD Tensile strength of from about 7,000 to about 18,000
typically 10,000 to 15,000 psi.
[0172] TD Tensile strength of from about 7,000 to about 18,000
typically, 10,000 to 15,000 psi.
[0173] MD Tensile elongation of from about 220 to about 350%.
[0174] TD Tensile elongation of from about 220 to about 350%.
[0175] MD Elmendorf Tear value of from about 10 to about 30
g/mil.
[0176] TD Elmendorf Tear value of from about 20 to about 60
g/mil.
[0177] Dart Impact (F.sub.50) of greater than 150 g.
[0178] For molding (injection, blow and extrusion) the following
mechanical properties (as measured by the appropriate ASTM test
method) may be desirable in the polymer. TABLE-US-00001 Yield Point
25 to 40, preferably 25 to 35 MPa Tensile Modulus 800 to 1000,
preferably 800 to 900 MPa Tensile Strength 20 to 45, preferably 25
to 40 MPa Notch Impact 140 to 160, typically about 150 kJ/M.sup.2
Flexural Strength 20 to 45, preferably 20 to 40 MPa Shear Strength
20 to 45, preferably 20 to 36 MPa Elongation at yield 10 to 15
typically 10 to 12% Elongation at break 100 to 1200%
[0179] The present invention will now be illustrated by the
following non-limiting examples.
EXAMPLES
Experimental
[0180] In the experiments the following abbreviations were used.
[0181] THF=tetrahydrofuran [0182] TMS=trimethyl silyl
[0183] Molecular weight distribution and molecular weight averages
(Mw, Mn, Mz) of resins were determined using high temperature Gel
Permeation Chromatography (GPC) according to the ASTM D6474:
"Standard Test Method for Determining Molecular Weight Distribution
and Molecular Weight Averages of Polyolefins". The system was
calibrated using the 16 polystyrene standards (Mw/Mn<1.1) in Mw
range 5.times.10.sup.3 to 8.times.10.sup.6 and 3 Hydrocarbon
Standards C.sub.60, C.sub.40, and C.sub.20.
[0184] The operating conditions are listed below: TABLE-US-00002
GPC Instrument: Polymer Laboratories .RTM. 220 equipped with a
refractive index detector Software: Viscotek .RTM. DM 400 Data
Manager with Trisec .RTM. software Columns: 4 Shodex .RTM. AT-800/S
series cross-linked styrene-divinylbenzene with pore sizes 10.sup.3
.ANG., 10.sup.4 .ANG., 10.sup.5.ANG., 10.sup.6 .ANG. Mobile Phase:
1,2,4-trichlorobenzene Temperature: 140.degree. C. Flow Rate: 1.0
ml/min Sample Preparation: Samples were dissolved in
1,2,4-trichloro- benzene by heating on a rotating wheel for four
hours at 150.degree. C. Sample Filtration: No Sample Concentration:
0.1% (w/v)
[0185] The determination of branch frequency as a function of
molecular weight was carried out using high temperature Gel
Permeation Chromatography (GPC) and FT-IR of the eluent.
Polyethylene standards with a known branch content, polystyrene and
hydrocarbons with a known molecular weight were used for
calibration.
[0186] Operating conditions are listed below: TABLE-US-00003 GPC
instrument: Waters .RTM. 150 equipped with a refractive index
detector IR Instrument: Nicolet Magna .RTM. 750 with a Polymer Labs
.RTM. flow cell Software: Omnic .RTM. 5.1 FT-IR Columns: 4 Shodex
.RTM. AT-800/S series cross-linked styrene-divinylbenzene with pore
sizes 10.sup.3 .ANG., 10.sup.4 .ANG., 10.sup.5 .ANG., 10.sup.6
.ANG. Mobile Phase: 1,2,4-Trichlorobenzene Temperature: 140.degree.
C. Flow Rate: 1.0 ml/min Sample Preparation: Samples were dissolved
in 1,2,4- trichlorobenzene by heating on a rotating wheel for five
hours at 150.degree. C. Sample Filtration: No Sample Concentration:
4 mg/g
Synthesis of Catalyst Component 1
[0187] EtMgBr (100 mL, 3M solution in diethyl ether) was added
dropwise to a solution of 4-methoxy-2-tert-butyl-phenol (290 mmol)
in tetrahydrofuran (THF) (350 mL) at ambient temperature to give an
amber solution. After 2 hrs of stirring, toluene (250 mL) was
added, and the ether and THF were removed by distillation.
Triethylamine (60.6 mL) and paraformaldehyde (21.8 g) were then
added as a white slurry in toluene. The reaction was stirred
overnight, followed by heating for 2 hours at 95.degree. C. to give
a cloudy orange solution. The resulting reaction mixture was poured
into 1 M HCl while cooling to 0.degree. C. The organic layer was
separated and the aqueous phase extracted with diethyl ether. The
combined organic phases were dried over Na.sub.2SO.sub.4, and then
evaporated to give an oily orange material. The oil was dissolved
in ethanol (250 mL) and to the clear orange solution was added
cyclohexylamine (32.9 mL). The reaction was stirred for 48 hours
giving a dark orange solution. The solution was cooled in a freezer
causing a yellow crystalline solid to separate. The product was
isolated by filtration and washed with cold ethanol. The imine
product (54 mmol) was dissolved in THF (200 mL) and added dropwise
to a stirring suspension of excess NaH (70 mmol) in THF (250 mL).
The yellow suspension was stirred for 48 hours, the excess NaH
removed by filtration and the solvent removed to give a bright
yellow solid. The sodium salt (46 mmol) was dissolved in THF (150
mL) and added to a suspension of ZrCl.sub.4. THF.sub.2 (23 mmol) in
THF (150 mL). The resulting yellow suspension was stirred for 48
hours. The solvent was removed giving impure product as a very
sparingly soluble yellow residue. The crude material was extracted
with several portions of CH.sub.2Cl.sub.2 followed by filtration
and solvent removal to give a yellow solid which was further washed
with cold CH.sub.2Cl.sub.2/ether to remove unreacted ligand.
Synthesis of (tBu.sub.3PN)(n-BuCpC.sub.6F.sub.5)TiCl.sub.2
[0188] Sodium cyclopentadiene (615 mmol) was dissolved in
tetrahydrofuran and a solution of perfluorobenzene (309 mmol) was
added as a 1:1 solution with THF over a 20 minute period. The
resulting mixture was for 3 hours at 60.degree. C., allowed to
cool, then added by cannula transfer to neat chlorotrimethylsilane
(60 mL) at 0.degree. C. over 15 minutes. The reaction was allowed
to warm to ambient temperature for 30 minutes, followed by slow
concentration over a 3 hour period to remove excess
chlorotrimethylsilane and solvents. The resulting wet solid was
slurried in heptane and filtered. Concentration of the heptane
filtrate gave crude (TMS)(C.sub.6F.sub.5)C.sub.5H.sub.4 as a brown
oil which was used without further purification.
(TMS)(C.sub.6F.sub.5)C.sub.5H.sub.4 (50 mmol) was dissolved in THF
and cooled to 0.degree. C. The solution was treated with n-BuLi (50
mmol), which was added dropwise. After stirring for 10 minutes at
0.degree. C., the reaction was allowed to warm to ambient
temperature and stirred for a further 1 hour. A cold solution of
n-butyl bromide (50 mmol) was prepared in THF (35 mL), and to this
was added the [(TMS)(C.sub.6F.sub.5)C.sub.5H.sub.3]Li solution. The
resulting mixture was stirred for 2 hours and the THF was removed
by evaporation under vacuum. The residue was extracted into heptane
(150 mL), filtered and the solvent was evaporated. TiCl.sub.4 (60
mmol) was added to the (n-Bu)(TMS)(C.sub.6F.sub.5)C.sub.5H.sub.3
via pipette and the solution was heated to 60.degree. C. for 3
hours. Removal of excess TiCl.sub.4 under vacuum gave a thick oil.
Addition of pentane caused immediate precipitation of product
((nBu)(C.sub.6F.sub.5) C.sub.5H.sub.3)TiCl.sub.3 which was isolated
by filtration. ((nBu)(C.sub.6F.sub.5)C.sub.5H.sub.3)TiCl.sub.3
(15.6 mmol) was mixed with (tBu).sub.3PN-TMS (15.6 mmol) in toluene
and stirred overnight at ambient temperature. The solution was
filtered and the solvent removed to give desired product.
Synthesis of (tBu.sub.3PN)(n-HexyIC.sub.6F.sub.5 Cp)TiCl.sub.2
[0189] (TMS)(C.sub.6F.sub.5)C.sub.5H.sub.4 (160 mmol, made as
described above) was dissolved in THF and cooled to -40.degree. C.
The solution was treated with n-BuLi (160 mmol), which was added
dropwise. After stirring for 10 minutes at 0.degree. C., the
reaction was allowed to warm to ambient temperature and stirred for
a further 30 minutes. To a solution of n-hexyl bromide (240 mmol)
in THF (100 mL) was added the
[(TMS)(C.sub.6F.sub.5)C.sub.5H.sub.3]Li solution at 0.degree. C.
The resulting mixture was stirred overnight at room temperature and
the volatiles were removed in vacuo. Vacuum distillation of the
crude residue gave sufficiently pure
(n-hexyl)(TMS)(C.sub.6F.sub.5)C.sub.5H.sub.3 for use in the next
step. Neat TiCl.sub.4 (48 mmol) was reacted with
(n-hexyl)(TMS)(C.sub.6F.sub.5)C.sub.5H.sub.3 (40 mmol) at
60.degree. C. After 3 hours, volatiles were removed and the residue
was triturated with heptane to give (n-HexylC.sub.6F.sub.5
Cp)TiCl.sub.3 which was used directly in the next step.
(n-HexyIC.sub.6F.sub.5 Cp)TiCl.sub.3 (24 mmol) was weighed into a
flask with tBu.sub.3PN-TMS (18 mmol) and toluene (40 mL) was added.
The mixture was stirred at 100.degree. C. for 2.5 hours and the
solvent was removed to give an oil. Heptane addition precipitated
the desired product as a yellow powder which was isolated by
filtration and washed further with heptane.
Preparation of Silica-Supported Aluminoxane (Mao)
[0190] Sylopol.RTM. XPO-2408 silica, purchased from Grace Davison,
was calcined by fluidizing with air at 200.degree. C. for 2 hours
and subsequently with nitrogen at 600.degree. C. for 6 hours. 44.6
grams of the calcined silica was added in 100 mL of toluene. 150.7
g of a MAO solution containing 4.5 weight % Al purchased from
Albemarle was added to the silica slurry. The mixture was stirred
for 1 hour at ambient temperature. The solvent was removed by
vacuum, yielding a free flowing solid containing 11.5 weight %
Al.
Example 1
Preparation of Catalyst A
[0191] In a glovebox, 1.37 g of silica-supported MAO prepared above
was slurried in 25 mL of toluene. Separately, 18 mg of catalyst
component 1 was dissolved in 10 mL of toluene, and 16 mg of
(tBu.sub.3PN)(C.sub.6F.sub.5)(n-Bu)CpTiCl.sub.2 was dissolved in 10
mL of toluene. Both catalyst solutions were added simultaneously to
the silica slurry. After one hour of stirring, the slurry was
filtered, yielding a clear filtrate. The solid component was washed
twice with toluene, and once with heptane. The final product was
dried in vacuo to 300 mTorr (40 Pa) and stored under nitrogen until
used.
Polymerization
[0192] A 2L stirred autoclave reactor was heated at 100.degree. C.
for 1 hour and thoroughly purged with nitrogen. 160 g of NaCl,
pre-dried in an oven at 160.degree. C. for at least a week, was
added in the reactor which was subsequently pressure purged three
times with nitrogen and twice with ethylene at 100C. The reactor
was then cooled to 90.degree. C. and an aliquot of 25 weight %
triisobutyl aluminum (TiBAL) was added. The amount of TIBAL was
such that the molar ratio of TiBAL to the total transition metal in
the catalyst to be added was around 500:1. 2.0 mL of purified
1-hexene was then added and the reactor was pressurized with 100
psig (689.4 KPa gage) of ethylene. 200 psig (1,378 KPa gage) of
ethylene was used to push 20.7 mg of Catalyst A from a catalyst
tubing into the reactor to start the reaction. During the
polymerization, the reactor pressure was maintained constant with
200 psig (1,378 KPa gage) of ethylene and 1-hexene was continuously
fed into the reactor as 10 weight % of ethylene feeding rate using
a mass flow controller. The polymerization was carried out at
90.degree. C. for 1 hour, yielding 38.0 g of polymer.
Example 2
[0193] The procedure was the same as Example 1, except that 27.5 mg
of Catalyst A was used for polymerization and 0.6 psi (4.1 KPa
gage) of hydrogen was pre-charged to the reactor prior to
polymerization, yielding 65.5 g of polymer.
[0194] The GPC profiles of the polymers produced in Examples 1 and
2 are shown in FIG. 1. In the absence of hydrogen, a polymer with
bimodal MW distribution was produced. However, in the presence of
hydrogen, the peak corresponding to the high MW fraction shifted to
a lower MW, resulting in a unimodal polymer. Hence, by adjusting
the level of hydrogen in the reactor, one can control the
polydispersity of polymers, changing them from a unimodal
distribution to a broad or bimodal distribution.
Example 3
Preparation of Catalyst B
[0195] In a glovebox, 137 g of silica-supported MAO prepared above
was slurried in 400 mL of toluene. Separately, 2.26 g of catalyst
component 1 was dissolved in 100 mL of toluene, and 1.24 g of
(tBU.sub.3PN)(n-hexylC.sub.6F.sub.5 Cp)TiCl.sub.2 was dissolved in
100 mL of toluene. Both catalyst solutions were added
simultaneously to the silica slurry. After one hour of stirring,
the slurry was filtered, yielding a clear filtrate. The solid
component was washed twice with toluene, and once with heptane. The
final product was dried in vacuo to 300 mTorr (40 Pa) and stored
under nitrogen until use.
Polymerization
[0196] A 2L stirred autoclave reactor was heated at 100.degree. C.
for 1 hr and thoroughly purged with nitrogen. 160 g of NaCl
pre-dried in an oven at 160.degree. C. for at least a week was
added in the reactor which was subsequently pressure purged three
times with nitrogen and twice with ethylene at 100C. The reactor
was then cooled to 83.degree. C. and an aliquot of 25 weight %
triisobutyl aluminum (TiBAL) was added. The amount of TiBAL was
such that the molar ratio of TiBAL to the total transition metal in
the catalyst to be added was around 500:1. 1.5 mL of purified
1-hexene was then added and the reactor was pressurized with 100
psig (689.4 KPa gage) of ethylene. 150 psig (1,034 KPa gage) of
ethylene was used to push 30.9 mg of Catalyst B from a catalyst
tubing into the reactor to start the reaction. During the
polymerization, the reactor pressure was maintained constant with
150 psig (1,034 KPa gage) of ethylene and 1-hexene was continuously
fed into the reactor as 10 weight % of ethylene feeding rate using
a mass flow controller. The polymerization was carried out at
83.degree. C. for 1 hour, yielding 37.1 g of polymer.
Example 4
Polymerization
[0197] A 2L stirred autoclave reactor was heated at 100.degree. C.
for 1 hour and thoroughly purged with nitrogen. 160 g of NaCl
pre-dried in an oven at 160.degree. C. for at least a week was
added in the reactor which was subsequently pressure purged three
times with nitrogen and twice with ethylene at 100C. The reactor
was then cooled to 83.degree. C. and an aliquot of 25 weight %
triisobutyl aluminum (TiBAL) was added. The amount of TiBAL was
such that the molar ratio of TiBAL to the total transition metal in
the catalyst to be added was around 500:1. 2.0 mL of purified
1-hexene was then added and the reactor was pressurized with 100
psig (689.4 KPa gage) of ethylene. 200 psig (1,378 KPa gage) of
ethylene was used to push 29.6 mg of Catalyst B from a catalyst
tubing into the reactor to start the reaction. During the
polymerization, the reactor pressure was maintained constant with
200 psig (1,378 KPa gage) of ethylene and 1-hexene was continuously
fed into the reactor as 10 weight % of ethylene feeding rate using
a mass flow controller. The polymerization was carried out at
83.degree. C. for 1 hour, yielding 45.1 g of polymer.
[0198] FIG. 2 shows the GPC profiles of polymers produced by
Examples 3 and 4. Due to the difference in the effect of ethylene
pressure on the activity of each catalyst component, the same dual
catalyst can produce resins with different molecular weight
distribution profiles when operated under different ethylene
pressures.
Example 5
[0199] Was carried out the same as Example 4, except that 29.9 mg
of Catalyst B was used and the polymerization was conducted at
90.degree. C., yielding 42.8 g of polymer.
Example 6
[0200] Was carried out the same as Example 4, except that 31.6 mg
of Catalyst B was used and the polymerization was conducted at
97.degree. C., yielding 50.9 g of polymer.
[0201] The GPC profiles of polymers produced in Examples 4-6 are
shown in FIG. 3. It is clear that at higher temperature the ratio
of the high MW fraction to the low MW fraction increases.
Example 7
Polymerization
[0202] A 75 L stirred bed gas phase continuous reactor similar to
that described in EP 0659 773 was used to produce copolymers
containing ethylene and hexene. The polymerization was run at
83.degree. C. with ethylene and hexene using Catalyst B to obtain
HDPE pipe bimodal resins. Isopentane was used in the process as a
cooling agent as well as to control the molecular weight
distribution of the resulting polymer. Nitrogen was used to
maintain the total reactor pressure to approximately 2,100 kPa. The
reactor composition was as follows: 55% ethylene, 0.41% hexene,
8.5% isopentane with the balance being nitrogen.
[0203] FIG. 4 is a GPC-FTIR profile of the polymer produced in
Example 7.
Example 8
Polymerization
[0204] Polymerization reaction was similar to Example 7 but with
reactor temperature at 88.degree. C.
[0205] FIG. 5 is as GPC-FTIR profile of the polymer produced in
Example 8.
[0206] By comparing FIGS. 4 and 5, it can be seen that temperature
effects are also present in a continuous operation mode on a larger
scale reactor. At 88.degree. C., the dual catalyst produces a resin
with a higher ratio of high MW fraction to low MW fraction than a
resin produced at 83.degree. C. Furthermore, the resin produced at
88.degree. C. exhibits increased comonomer incorporation into the
high MW fraction relative to the resin obtained at 83.degree.
C.
Example 9
[0207] Example 9 was carried out the same as Example 7, except that
isopentane was not fed into the reactor during the course of
polymerization.
[0208] FIG. 6 compares the GPC profiles of polymers produced by
Examples 7 and 9. In the presence of isopentane, the ratio of the
high MW fraction to the low MW fraction decreases.
[0209] The examples shown above demonstrate that when the
individual catalyst components in a mixed catalyst respond
differently to hydrogen, temperature, ethylene pressure and level
of a non-polymerizable hydrocarbon, the polymer composition (the
ratio of the high MW fraction to the low MW fraction and the
comonomer placement) can be controlled by the conditions of the
polymerization process.
* * * * *