Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
The present invention relates the gas phase polymerization of
olefins, and particularly alpha olefins in the presence of a single site
catalyst. Processes for the gas phase polymerization of olefins are well
known and described in a number of patents including for example U.S.
Patents 4,543,399 and 4,588,790 issued to Jenkins, III et al September
24,1985 and May 13, 1986, respectively, assigned to Union Carbide.
BACKGROUND OF THE INVENTION
United States Patent 4,182,810 issued Jan. 8, 1980, assigned to
Phillips Petroleum Company teaches the use of antifouling agents
comprising a mixture of a polysulphone copolymer, a polyamide and a
sulphonic acid in a slurry phase polymerization. The Patent does not
teach or suggest the use of similar systems in a gas phase polymerization.
United States Patent 5,026,795 issued June 25, 1991 assigned to
Phillips Petroleum Company teaches the use of an antistatic agent
comprising of a polysulphone copolymer, a polyamide and a sulphonic
acid in a gas phase polymerization. The only teaching of a catalyst in the
disclosure is a silica/titanium/chromium oxide catalyst. This is not the
single site catalyst of the present invention.
United States Patent 5,030,700 issued July 9, 1991 assigned to
Exxon and immediately withdrawn apparently related to a process to
control static in a gas phase process in which the catalyst was a
metallocene catalyst. Applicant references the case but has been unable
to obtain a copy of the Patent or even an abstract of the Patent.
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WO 01/18067 published March 15, 2001, in the name of BP
Chemicals Limited discloses similar compositions may be used to control
static in gas phase reactors using Ziegler Natta type catalysts. The
reference does not teach or suggest the anti static agent would be useful
in conjunction with single site catalysts.
SUMMARY OF THE INVENTION
The present invention provides In a process for the fluidized bed
gas phase polymerization of one or more C2_8 alpha in the presence of a
single site catalyst and an activator the improvement comprising including
in the gas phase from 0.5 to 20,000 ppm based on the weight of the olefin
in the reactor of an anti static agent comprising
(i) from 3 to 48 parts by weight of one or more polysulfones
comprising:
(a) 50 mole % of sulphur dioxide;
(b) 40 to 50 mole % of a Cs_2o an alpha olefin; and
(c) from 0 to 10 mole % of a compound of the formula ACH=CHB
where A is selected from the group consisting of a carboxyl radical and a
C~_~5 carboxy alkyl radical; and B is a hydrogen atom or a carboxyl radical
provided if and B are carboxyl radicals A and B may form an anhydried;
(ii) from 3 to 48 parts by weight of one or more polymeric polyamides
of the formula:
RN[(CH2 CHOHCH2NR')a-(CH2CHOHCH2NR'-R2-NH)b-
(CH2CHOHCH2NR3)~HX]H2_x
wherein R' is an aliphatic hydrocarbyl group of 8 to 24 carbon atoms,R2 is
an alkylene group of 2 to 6 carbon atoms,R3 is the group-R2-HNR', R is
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R' or an N-aliphatic hydrocarbyl alkylene group having the formula
R'NHR2 ; a, b and c are integers from 0 to 20 and x is 1 or 2 ; with the
proviso that when R is R'
then a is greater than 2 and b = c = 0, and when R is R' NHR2-then a is 0
and the sum of b+c is an integer from 2 to 20;
(iii) from 3 to 48 parts by weight of C~o_2o alkyl or arylalkyl sulphonic
acid.
and optionally from 0 to 150 parts by weight of a solvent or diluent.
DETAILED DESCRIPTION.
As used in this specification the term single site catalyst
includes homogeneous catalysts producing under typical conditions a
polymer having a polydispersity (Mw/Mn) of less than 7; preferably less
than 4.
Such catalysts tend to be complexes of transition metals, preferably
an early transition metal (e.g. Ti, V, Zr and Hf) and generally having two
bulky ligands. In many of the well known single site catalysts typically one
of the bulky ligands is a cyclopentadienyl-type ligand. These
cyclopentadienyl-type ligands comprise a C5_~3 ligand containing a 5-
membered carbon ring having delocalized bonding within the ring and
bound to the metal atom through covalent r15 bonds which are
unsubstituted or may be further substituted (sometimes referred to in a
short form as Cp ligands). Cyclopentadienyl-type ligands include
unsubstituted cyclopentadienyl, substituted cyclopentadienyl,
unsubstituted indenyl, substituted indenyl, unsubstituted fluorenyl and
substituted fluorenyl. An exemplary list of substituents for a
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cyclopentadienyl-type ligand includes the group consisting of C,_~o
hydrocarbyl radicals (including phenyl and benzyl radicals), which
hydrocarbyl substituents are unsubstituted or further substituted by one or
more substituents selected from the group consisting of a halogen atom,
preferably a chlorine or fluorine atom and a C~.4 alkyl radical; a C~_8 alkoxy
radical; a C6_~o aryl or aryloxy radical; an amido radical which is
unsubstituted or substituted by up to two C~_a alkyl radicals; a phosphido
radical which is unsubstituted or substituted by up to two C~_8 alkyl
radicals; silyl radicals of the formula -Si-(R)3 wherein each R is
independently selected from the group consisting of hydrogen, a C~_a alkyl
or alkoxy radical, and C6_~o aryl or aryloxy radicals; and germanyl radicals
of the formula Ge-(R)3 wherein R is as defined directly above.
If there are two such bulky ligands (i.e. bis Cp) the catalysts are
metallocene-type catalysts. The Cp ligand may be bridged to another Cp
ligand by a silyl bridge or a short chain (C») alkyl radical. The Cp-type
ligand may be bridged to an amido radical which may be further
substituted by up to two additional substituents. Such bridged complexes
are sometimes referred to as constrained geometry catalysts. The catalyst
may contain a CP type ligand together with other bulky ligands such as a
phosphinimine ligand or a ketimide ligand. All of the foregoing types of
catalyst are intended to come within the phrase single site catalyst.
Gas phase polymerization of olefins is well known. Typically, in gas
phase polymerization of polyolefins (such as polyethylene) a gaseous feed
stream comprising ethylene and one or more C3_6 copolymerizable
monomers typically butene or hexene or both, together with a ballast gas
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such as nitrogen, optionally a small amount of C~_2 alkanes (i.e. methane
and ethane) and further optionally a molecular weight control agent
(typically hydrogen) is fed to a reactor. Typically the feed stream passed
through a distributor plate at the bottom of the reactor and traverses a
catalyst bed, typically a fluidized catalyst bed. A small proportion of the
olefin monomers in the feed stream react with the catalyst. The unreacted
monomer and the other non-polymerizable components in the feed stream
exit the bed and typically enter a disengagement zone where the velocity
of the feed stream is reduced so that entrained polymer falls back into the
fluidized bed. Typically the gaseous stream leaving the top of the reactor
is then passed through a compressor. The compressed gas is then cooled
by passage through a heat exchanger to remove the heat of reaction. The
heat exchanger may be operated at temperatures below about 65° C,
preferably at temperatures from 20° C to 50° C.
Polymer is removed from the reactor through a series of vessels in
which monomer is separated from the off gases. The polymer is
recovered and further processed. The off gases are fed to a monomer
recovery unit. The monomer recovery unit may be selected from those
known in the art including a distillation tower (1.e. a C2 splitter), a
pressure
swing adsorption unit and a membrane separation device. Ethylene and
hydrogen gas recovered from the monomer recovery unit are fed back to
the reactor. Finally, make up feed stream is added to the reactor below
the distributor plate.
The polymerization is a particulate polymerization and there is a
static electricity build up on the polymer particles in the reactor bed. The
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particles may tend to be attracted to the walls of the reactor and this over
the long run may result in sheeting and formation of agglomerates.
It has now been found that an antistatic aid comprising:
(1) a polysulphone copolymer,
(2) a polymeric polyamine, and
(3) an oil-soluble sulphonic acid.
may be used to reduce static (or static electricity) in the gas phase
polymerization of olefins in the presence of a single site catalyst.
The antistatic can be added at any location of the fluidized bed
polymerization process, including but not limited to the reactor itself, below
the distributor plate or above the distributor plate in the fluidized bed,
above the fluidized bed, in the velocity reduction zone, anywhere in the
reaction loop or recycle line, etc. According to a preferred embodiment of
the present invention, the process aid additive is directly added into the
polymerization zone, more preferably directly into the fluidized bed. The
antistatic may be added near the distributor plate typically the bottom third
of the bed. The antistatic may be added at several different locations of
the process.
Care should be taken if the antistatic is to be added in admixture
with the catalyst component or the cocatalyst.
The polysulphone component of the antistatic in accordance with
the present invention is typically a linear polymer believed to be alternating
copolymers of the olefins and sulphur dioxide, having a 1:1 molar ratio of
the comonomers with the olefins in head to tail arrangement. The
polysulphone should consist of about 50 mole percent of units derived .
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from sulphur dioxide; about 40 to 50 mole percent of units derived from
one or more C6_2o alpha olefins, and optionally from about 0 up to about 10
mole percent of units derived from an olefinic compound having the
formula ACH=CHB where A is a group having the formula- (CxH2x)-
COOH wherein x is from 0 to about 17, and B is hydrogen or carboxyl, with
the proviso that when B is carboxyl, x is 0, and wherein A and B together
can be a dicarboxylic anhydride group.
The polysulphone used in the present invention generally has a
weight average molecular weight in the range 30,000 to 1,000,000,
preferably from 50,000 to 500,000. Preferably, the alpha olefins in the
sulphone are straight chain olefins having up to 18 carbon atoms,
including 1- hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene; 1-
hexadecene and 1-octadecene.
If present the ACH=CHB components of ;the sulphone polymer may
be derived from malefic acid, acrylic acid, 5-hexenoic acid.
The manufacture of polysulphones is more fully described in US
Patent specifications 3,811,848 and 3,917,466. The text of which is herein
incorporated by reference.
A particularly useful polysulphone is a copolymer of 1-decene and
sulphur dioxide having an inherent viscosity (measured as a 0.5 weight
percent solution in toluene at 30 C) ranging from about 0.04 dl/g to 1.6
dl/g.
The polyamine component in accordance with the present invention
has the general formula: RN[(CH2 CHOHCH2NR')a-(CH2CHOHCH2NR'-R2-
NH)b-(CH2CHOHCH2NR3)~HX]H2_X wherein R' is an aliphatic hydrocarbyl
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group of 8 to 24 carbon atoms,R2 is an alkylene group of 2 to 6 carbon
atoms,R3 is the group-R2-HNR', R is R' or an N-aliphatic hydrocarbyl
alkylene group having the formula R'NHR2 ; a, b and c are integers from 0
to 20 and x is 1 or 2 ; with the proviso that when R is R' then a is greater
than 2 and b = c = 0, and when R is R'NHR2-then a is 0 and the sum of
b+c is an integer from 2 to 20;
US Patent 3,917,466 discloses the polyamines which can be used
in the present invention.
One method of preparing the polyamine comprises heating an
aliphatic primary monoamine or N-aliphatic hydrocarbyl alkylene diamine
with epichlorohydrin in 1: 1 to 1: 1.5 molar ratio at a temperature of 50 C to
100 C in a solvent, such as xylene and isopropanol, and adding a strong
base, such as sodium hydroxide and continuing the heating for about 2
hours. The product containing the polymeric polyamine is then separated
by decanting and flashing off the solvent.
The amine used to make the polyamine is preferably an N-aliphatic
alkaline diamine or a primary aliphatic amine containing at least 8 carbon
atoms and preferably 12 or more carbon atoms with epichlorohydrin. The
primary aliphatic amines include those derived from fatty acids such as tall
oil, tallow, soy bean oil, coconut oil and cotton seed oil. Preferably the
polyamine is the reaction of N-tallowamine (N- tallow-1, 3-
diaminopropane) with epichlorohydrin in a molar ratio of from 1: 1 to 1:2
preferably 1: 1.5 mole. One method of preparing such a polyamine is
disclosed in U.S. Patent 3,917,466. One such reaction product is "Polyflo
130" sold by Universal Oil Company.
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The oil-soluble sulphonic acid in the antistatic may be any oil-
soluble sulphonic acid such as a C~o_2o alkyl or arylalkyl sulphonic acid. A
useful sulphonic acid is petroleum sulphonic acid resulting from treating
oils with sulphuric acid. Preferred oil-soluble sulphonic acids are
dodecylbenzene sulphonic acid and dinonylnaphthyl sulphonic acid.
The antistatic of the present invention comprises from 3 to 48,
preferably from 5 to 40, most preferably from 10 to 40 parts by weight of
polysulphone; from 3 to 48, preferably from 5 to 40, most preferably from
10 to 40 parts by weight of polymeric polyamine and from 3 to 48,
preferably from 5 to 40, most preferably from 10 to 40 parts by weight of
sulphonic acid. The antistatic may be dissolved or dispersed in from 0 to
150, preferably 100 to 150 parts by weight of a solvent or diluent.
Suitable solvents include aromatic, paraffin and cycloparaffin
compounds.
The solvents are preferably selected from the group consisting of
benzene, toluene, xylene, cyclohexane, fuel oil, isobutane, kerosene and
mixtures thereof. According to one embodiment of the present invention,
the anti static is diluted in a conventional hydrocarbon diluent, which can
be the same or different from the solvents listed above, preferably butane,
pentane or hexane. When a diluent is used, the antistatic (including the
solvent therefor) is preferably present in an amount comprised between
0.1 and 500 g per litre of diluent, preferably between 1 and 50 g per litre of
diluent.
The catalyst may be a single site type catalyst typically comprising
a transition metal, preferably an early transition metal (e.g. Ti, V, Zr and
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Hf) and generally having two bulky ligands. In many of the well known
single site catalysts typically one of the bulky ligands is a cyclopentadienyl-
type ligand. . These cyclopentadienyl-type ligands comprise a C5_13 ligand
containing a 5-membered carbon ring having delocalized bonding within
the ring and bound to the metal atom through covalent r~5 bonds which are
unsubstituted or may be further substituted (sometimes referred to in a
short form as Cp ligands). Cyclopentadienyl-type ligands include
unsubstituted cyclopentadienyl, substituted cyclopentadienyl,
unsubstituted indenyl, substituted indenyl, unsubstituted fluorenyl and
substituted fluorenyl. An exemplary list of substituents for a
cyclopentadienyl-type ligand includes the group consisting of C~_~o
hydrocarbyl radicals (including phenyl and benzyl radicals), which
hydrocarbyl substituents are unsubstituted or further substituted by one or
more substituents selected from the group consisting of a halogen atom,
preferably a chlorine or fluorine atom and a C~.~ alkyl radical; a C~_8 alkoxy
radical; a C6_~o aryl or aryloxy radical; an amido radical which is
unsubstituted or substituted by up to two C,_8 alkyl radicals; a phosphido
radical which is unsubstituted or substituted by up to two C~_8 alkyl
radicals; silyl radicals of the formula -Si-(R)3 wherein each R is
independently selected from the group consisting of hydrogen; a C~_8 alkyl
or alkoxy radical, and Cs_,o aryl or aryloxy radicals; and germanyl radicals
of the formula Ge-(R)3 wherein R is as defined directly above.
If there are two such bulky ligands (i.e. bis Cp) the catalysts are
metallocene-type catalysts. The Cp ligand may be bridged to another Cp
ligand by a silyl bridge or a short chain (C») alkyl radical. The Cp-type
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ligand may be bridged to an amido radical which may be further
substituted by up to two additional substituents. Such bridged complexes
are sometimes referred to as constrained geometry catalysts.
Broadly, the transition metal complex (or catalyst) suitable for use in
the present invention has the formula:
(L)n - M - (X)p
wherein M is a transition metal preferably selected from Ti, Hf and Zr (as
described below); L is a monanionic ligand selected from the group
consisting of a cyclopentadienyl-type ligand, a bulky heteroatom ligand (as
described below) and a phosphinimine ligand (as described below); X is
an activatable ligand which is most preferably a simple monanionic ligand
such as alkyl or a halide (as described below); n may be from 1 to 3,
preferably 2 or 3; and p may be from 1 to 3, preferably 1 or 2, provided
that the sum of n+p equals the valence state of M, and further provided
that two L ligands may be bridged by a silyl radical or a C» alkyl radical.
If one or more of the L ligands is a phosphinimine ligand the
transition metal complex may be of the formula:
( ~ I)m
(L)n - M - (X)p
wherein M is a transition metal preferably selected from Ti, Hf and Zr (as
described below); PI is a phosphinimine ligand (as described below); L is a
monanionic ligand selected from the group consisting of a
cyclopentadienyl-type ligand or a bulky heteroatom ligand (as described
below); X is an activatable ligand which is most preferably a simple
monanionic ligand such as an alkyl or a halide (as described below); m is
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1 or 2; n is 0 or 1; and p is an integer fixed by the valence of the metal M
(i.e. the sum of m+n+p equals the valence state of M).
In one embodiment the catalysts are group 4 metal complexes in
the highest oxidation state. For example, the catalyst may be a bis
(phosphinimine) dichloride complex of titanium, zirconium or hafnium.
Alternately, the catalyst contains one phosphinimine ligand, one "L" ligand
(which is most preferably a cyclopentadienyl-type ligand) and two "X"
ligands (which are preferably both chloride).
The preferred metals (M) are from Group 4, (especially titanium,
hafnium or zirconium) with titanium being most preferred.
The catalyst may contain one or two phosphinimine ligands, which
are covalently bonded to the metal. The phosphinimine ligand is defined
by the formula:
R3
R3-P=N-
R3
wherein each R3 is independently selected from the group consisting of a
hydrogen atom; a halogen atom; C~_2o, preferably C~_~o hydrocarbyl
radicals which are unsubstituted by or further substituted by a halogen
atom; a C~_a alkoxy radical; a C6_~o aryl or aryloxy radical; an amido
radical;
a silyl radical of the formula:
-S~-(R2)3
wherein each R2 is independently selected from the group consisting of
hydrogen, a C~_$ alkyl or alkoxy radical, and C6_~o aryl or aryloxy radicals;
and a germanyl radical of the formula:
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Ge-(R2)s
wherein R2 is as defined above.
The preferred phosphinimines are those in which each R3 is a
hydrocarbyl radical, preferably a C~_6 hydrocarbyl radical. A particularly
preferred phosphinimine is tri-(tertiary butyl) phosphinimine (i.e. wherein
each R3 is a tertiary butyl group).
Preferred 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
heteroligand.
As used herein, the term "heteroligand" refers to a ligand which
contains at least one heteroatom selected from the group consisting of
boron, nitrogen, oxygen, phosphorus or sulfur. The heteroligand may be
sigma or pi-bonded to the metal. Exemplary heteroligands include
ketimide ligands, silicone-containing heteroligands, amido ligands, alkoxy
ligands, boron hetrocyclic ligands and phosphole ligands, all as described
below.
As used herein, the term "ketimide ligand" refers to a ligand which:
(a) is bonded to the transition metal via a metal-nitrogen atom
bond;
(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
(c) has two substituents Sub 1 and Sub 2 (described below)
which are bonded to the carbon atom.
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Conditions a, b and c are illustrated below:
Sub 1 Sub 2
C
I I
N
I
metal
The substituents "Sub 1" and "Sub 2" may be the same or different.
Exemplary substituents include hydrocarbyls having from 1 to 20 carbon
atoms, silyl groups, amido groups and phosphido groups. For reasons of
cost and convenience it is preferred that these substituents both be
hydrocarbyls, especially simple alkyls and most preferably tertiary butyl.
Silicon containing hetroligands are defined by the formula:
- (p)SiRXRyRZ
wherein the - denotes a bond to the transition metal and p is sulfur or
oxygen:
The substituents on the Si atom, namely RX, RY and RZ are required
in order to satisfy the bonding orbital of the Si atom. The use of any
particular substituent RX, RY or RZ is not especially important to the
success of this invention. It is preferred that each of RX, Ry and RZ is a
C~_2
hydrocarbyl group (i.e. methyl or ethyl) simply because such materials are
readily synthesized from commercially available materials.
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.
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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 C1_1o straight chained,
branched or cyclic alkyl radical or a C6_13 aromatic radical which radicals
are unsubstituted or further substituted by one or more C1_4 alkyl radicals
(e.g. 2, 6 di-tertiary butyl phenoxy).
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. Patent's 5,637,659,
5,554,775 and the references cited therein).
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 C4PH4 (which is analogous to cyclopentadiene with one
carbon in the ring being replaced by phosphorus). The phosphole ligands
may be substituted with, for example, C1_2o 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. Patent 5,434,116 (Sone, to Tosoh).
The term "activatable ligand" or "leaving ligand" refers to a ligand
which may be activated by the alumoxane, (also referred to as an
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"activator"), to facilitate olefin polymerization. Exemplary activatable
ligands are independently selected from the group consisting of a
hydrogen atom; a halogen atom, preferably a chlorine or fluorine atom; a
C~_~o hydrocarbyl radical, preferably a C» alkyl radical; a C~_~o alkoxy
radical, preferably a C1~ alkoxy radical; and a C5_~o aryl oxide radical; each
of which said hydrocarbyl, alkoxy, and aryl oxide radicals may be
unsubstituted by or further substituted by one or more substituents
selected from the group consisting of a halogen atom, preferably a
chlorine or fluorine atom; a C~_$ alkyl radical; preferably a C~~, alkyl
radical;
a C~_$ alkoxy radical, preferably a C» alkoxy radical; a C6_~o aryl or aryloxy
radical; an amido radical which is unsubstituted or substituted by up to two
C~_8, preferably C~.~ alkyl radicals; and a phosphido radical which is
unsubstituted or substituted by up to two C~_8, preferably C» alkyl radicals.
The number of activatable ligands depends upon the valence of the
metal and the valence of the activatable ligand. The preferred catalyst
metals are Group 4 metals in their highest oxidation state (i.e. 4+) and the
preferred activatable ligands are monoanionic (such as a halide -
especially chloride, or C» alkyl - especially methyl). One useful group of
catalysts contain a phosphinimine ligand, a cyclopentadienyl ligand and
two chloride (or methyl) ligands bonded to the Group 4 metal. In some
instances, the metal of the catalyst component may not be in the highest
oxidation state. For example, a titanium (III) component would contain
only one activatable ligand.
As noted above, one group of catalysts is a Group 4 organometallic
complex in its highest oxidation state having a phosphinimine ligand, a
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cyclopentadienyl-type ligand and two activatable ligands. These
requirements may be concisely described using the following formula for
the preferred catalyst:
I)m
~L)n - M - ~X)p
wherein: M is a metal selected from Ti, Hf and Zr; PI is as defined above,
but preferably a phosphinimine wherein R3 is a C~_6 alkyl radical, most
preferably a t-butyl radical; L is a ligand selected from the group consisting
of cyclopentadienyl, indenyl and fluorenyl ligands which are unsubstituted
or substituted by one or more substituents selected from the group
consisting of a halogen atom, preferably chlorine or fluorine; C~~ alkyl
radicals; and benzyl and phenyl radicals which are unsubstituted or
substituted by one or more halogen atoms, preferably fluorine; X is
selected from the group consisting of a chlorine atom and C» alkyl
radicals; m is 1; n is 1; and p is 2.
In one embodiment of the present invention the transition metal
complex may have the formula: [(Cp)qM[N=P(R3)]fX9 wherein M is the
transition metal; Cp is a C5_~g ligand containing a 5-membered carbon ring
having delocalized bonding within the ring and bound to the metal atom
through covalent r15 bonds and said ligand being unsubstituted or up to
fully substituted with one or more substituents selected from the group
consisting of a halogen atom, preferably chlorine or fluorine; C~~ alkyl
radicals; and benzyl and phenyl radicals which are unsubstituted or
substituted by one or more halogen atoms, preferably flurorine; R3 is a
substituent selected from the group consisting of C,_~o straight chained or
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branched alkyl radicals, C6_1o aryl and aryloxy radicals which are
unsubstituted or may be substituted by up to three C1~ alkyl radicals, and
silyl radicals of the formula -Si-(R)3 wherein R is C1~ alkyl radical or a
phenyl radical; L is selected from the group consisting of a leaving ligand;
q is 1 or 2; f is 1 or 2; and the valence of the transition metal - (q+f) = g.
Typically the single site catalysts are activated using alumoxanes.
Alumoxanes have the formula (R4)2A10(R4A10)n,Al(R4)2 wherein each R4 is
independently selected from the group consisting of C1_2o hydrocarbyl
radicals, m is from 3 to 50. Preferably m is from 5 to 30. Most preferably
R4 is selected from the group consisting of C1_6, most preferably C1~
straight chained or branched alkyl radicals. Suitable alkyl radicals include
a methyl radical, an ethyl radical, an isopropyl radical and an isobutyl
radical. In some commercially available alumoxanes R4 is a methyl
radical.
The catalyst useful in accordance with the present invention may
have a molar ratio of aluminum from the alumoxane to transition metal
from 5 to 300: 1, preferably from 25 to 200:1, most preferably from 50 to
120:1. Typically the alumoxane loading on the support will be from 1 to 40
weight % based on the (weight of the) support, preferably from 2 to 30
weight % based on the (weight of the) support, most preferably from 5 to
20 weight % based on the (weight of the) support. The corresponding
loading of transition metal from the single site catalyst will be within the
above specified ratio of AI: transition metal. Generally the loading of
transition metal on the support will be from 0.01 to 5 weight % based on
the (weight of the) support, preferably from 0.05 to 2 weight % of transition
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metal based on the (weight of the) support, most preferably from 0.1 to 1
weight % of transition metal based on the (weight of the) support.
The catalysts are supported. The supports useful in accordance
with the present invention typically comprise a substrate of aluminum or
silica having a pendant reactive moiety. The reactive moiety may be a
siloxy radical or more typically is a hydroxyl radical. The preferred support
is silica or alumina. The support should have a particle size from about 10
to 250 microns, preferably from about 30 to 150 microns. The support
should have a large surface area typically greater than about 3 m2/g,
preferably greater than about 50 m2/g, most preferably from 100 m2/g to
1,000 m2/g. The support will be porous and will have a pore volume from
about 0.3 to 5.0 ml/g, typically from 0.5 to 3.0 mllg. Supports, which are
specifically designed to be an agglomeration of subparticles are also
useful.
It is important that the support be dried prior to the initial reaction
with the catalyst or a catalyst component such as an aluminum compound.
Generally the support may be heated at a temperature of at least 200
°C
for up to 24 hours, typically at a temperature from 500 °C to 800
°C for
times from about 2 to 20 hours. The resulting support will be free of
adsorbed water and should have a surface hydroxyl content from about
0.1 to 5 mmol/g of support, preferably from 0.5 to 3 mmol/g.
The present invention will be illustrated by the following non-limiting
examples in which unless otherwise indicated parts is parts by weight (e.g.
g) and % is weight %.
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EXAMPLES
Example 1
A technical scale reactor similar to that disclosed in EP 0 659,773,
was used to polymerize polyethylene (hexene: ethylene molar ratio of
about 0.0109) using a supported catalyst which was a dichloro CpC6F5 tri-
t-butyl phosphinimido titanium complex supported on silica activated with
MAO at a 1:120 molar ratio of Ti: AI. The reactor was operated in a
conventional mode.
During the polymerization an anti static of the present invention
commercially available under the Trademark STADIS 425 was feed to the
reactor in an amount varying from 0 to 100 parts per million (ppm) based
on the bed weight.
The anti static agent of the present invention exhibited minimum
effects on the polymerization. After the experiment the reactor was clear
of polymer residue normally attributed to static.
Example 2
To more clearly demonstrate the antistatic properties of the
compositions of the present invention a further experiment was conducted.
Several grams of polymer prepared with the same catalyst as used in
experiment 1 were placed in two plastic test tubes. A wooden applicator
was dipped into Stadis 425 and briefly stirred in one of the samples. The
test tubes were then sealed and shaken for about 5 minutes after which
they were examined for static. The polymer in the test tube treated with
the STADIS 425 had lower levels of static demonstrated by slignificantly
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low levels of attraction of polymer to the hand of the experimentor when
the test tube was touched.
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