Note: Descriptions are shown in the official language in which they were submitted.
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ALUMlNOXANE PROCESS ANI~ P~ODUCT
t, This invention relates generally to the p~ lion of alllminox~nes and more
particularly to the p~ ion of hydrocarbyl~ minc-xanes, such as methylaluminoxane,
'1 by reacting a hydrocarbyl alumim~m compound with water which contains a stabilizing
5 agent, such as a metal salt, which solution is dispersed in an organic solvent.
Vandenberg, U. S. 3,219,591 reported the catalytic activity of compounds formed
by the reaction of trialkyl alu~ with limited amounts of water in the polymeri7~tion
of epichlorohydrin and other oxiranes. Shortly thereaf[er, Manyik, et al. U.S. 3,242,099
reported the use of aluminoxanes, made by reacting 0.85 - 1.05 moles of water with
10 hydrocarbyl al-l"l;..l~ll compounds such as kiisobutylal-.,..i.~l."" as co-catalysts with
certain kansition metal compounds in the polymeri7~tion of mono-unsaturated alpha-
olefins; e.g. ethylene and propylene. Isobutylaluminoxane was also made by adlding an
equalmolequantityofwatertoaheptanesolutionoftriisobutylal-,."i"l.."
Manyik, et al. U.S. 3,300,458 prepared alkylaluminoxane by passing a hydro-
carbon through water to form a wet hydrocarbon and mixing the wet hydrocarbon and an
alkyl alumimlm/hydrocarbon solution in a conduit.
Schf-~n1h~l, et al. U.S. 4,730,071 show the ~ ~a~ion of methyl~ minc xane by
dispersing water in toluene using an ultrasonic bath to cause the dispersion and then
adding a toluene solution of trimethylz~ minllm to the dispersion. Schoenthal, et al. U.S.
4,730,072 is similar except it uses a high speed, high shear-in~ cing impeller to form the
water dispersion.
Edwards, et al. U.S. 4,722,736 describe an aluminoxane process in which water
is introduced below the surface of a solution of hydrocarbyl ~ minnm ~ rent to a stirrer
which serves to immediately disperse the water in the hydrocarbon solution.
A problem associated with free water addition to trialkylalllminllm to produce
t aluminoxane solutions in organic solvents is that the solutions may produce gell and/or
small particles which aggregate to form gel on et~n~ling Even when the particles and/or
gel are removed by filtration, additional gel can forrn in the solution after 2 or 3 weeks,
especially when originally-prepared dilute solutions are concentrated to contain higher
aluminoxane contents which are convenient for storage, shipment and use.
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Sangokoya, U.S. Patent No. 5,157,137 describes a process for treating ~AO with
an anhydrous salt and/or hydroxide of an alkali or ~Ik~lin~ earth metal to inhibit gel and
gel forming compounds.
We have now discovered a process for making alurninoxanes by free water
S addition which provides unique, gel free, stable products.
In accordance with this invention there is provided a process for making an
aluminnx~ne, said process compt~i~in~ reacting water which contains a stabilizing agent
with a hydrocarbyl aluminum compound in an organic solvent so as to produce an
aluminoxane product.
Also provided is a new stable aluminoxane product prepared by this novel process.
~ydrocarbylaluminoxanes may exist in the form of linear, cyclic, caged or
polymeric structures with the simplest compounds being a tetraalkylaluminoxane such as
tetramethylaluminoxane, (CH3)2AIOAl(CH3)2, or tetraethyl~ minoxane, (C: 2H5)2AlOAl-
(C2H5)2. The compounds p.~re.led for use in olefin polymerization catalysts usually
contain about 4 to 20 ofthe repeating units:
~ Al - O ~
where R is C,-C8 alkyl and is preferably methyl. The exact structure of ~lllminoxanes has
not been defined and they may contain linear, cyclic, caged and/or cross-linked species.
Methylaluminoxanes (MAOs) normally have lower solubility in organic solvents than
higher alkylaluminoxanes and the methylaluminoxane solutions tend to be cloudy or
gelatinous due to the separation of particles and agglomerates. In order to improve the
solubility of the methylaluminoxane, higher alkyl groups, e.g. C2 to C20 can be included
such as by hydrolyzing a mixture of trimethylalllmin--m with a C2 to C20 alkylzlll-min--m
compound such as, for example, triethylal--min--m, tri-n-propyl-al--minl-m, triisobutyl-
minl-nn, tri-n-hexylalllmin~lnn~ tri-n-octylal--minum or a triarylal~-min--m Such mixed
methyl higher alkyl or aryl ahlmin- x~n~s are included in the term "methylaluminoxane"
as used herein.
Any hydrocarbyl alllminnm compound or mixture of compounds capable of
reacting with water to form an aluminoxane can be used. This includes, ~or example,
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trialkylalllminllm, triarylalllmimlm, or mixed alkyl-aryl alllmimlm
The preferred hydrocarbyl aluminum compounds are the alkyl alllminllm
compounds, especially trialkylal~lmimlrn compounds such as trimethylall~mimlm,
triethylalllminl-m, triisobutylalllminum, tri-n-hexyl~lllminllm, or trioctyl~ll..,.i..-l", Of
5 these, the more preferred are the ki-cl-4-alkylalllminllm compounds.
Of the various hydrocarbyl aluminoxanes, methylaluminoxane and ethyl-
aluminoxane are the more difficult to prepare because of the extreme reactivity of
trimethylalllmimlm and triethylalllminllm with water. The most reactive is trimethyl-
s~luminllm and, accordingly, the prer~ d use of the process of the invention is ~o make
1 0 methylaluminoxane.
The reaction is carried out in an inert solvent. Any inert solvent can be used. The
d solvents are aliphatic and aromatic hydrocarbons. Aromatic hydrocarbons are
more preferred such as toluene, xylene, ethylbenzene, cumene, or mesitylene. The most
preferred solvent is toluene.
The concentration of the hydrocarbyl alul llhlulll compounds in the inert solvent
can range from about 1-30 weight percent. A ~lc;r~ d concentration is about 5-10 weight
percent, more preferably 10-15 weight percent.
The stabilizing agents are combined with the water used to hydrolyze the
hydrocarbyl al~ lll.l compounds. The term "stabilizing agent" as used herein includes
any water soluble inorganic compound which is effective to provide aLI~yl~lllmin~ xanes
having improved solubility in organic solvents when added to the water used to hydrolyze
the hydrocarbyl alllminllm compound. Preferred are water soluble (at least I gram/100
mL H2O at 25~C) metal salts and their ammonium analogs and especially alkali andzllk~line earth metal hsllicles Non-limi~ing examples of such compounds include, NaBr,
NaF, NaCI, LiCl, LiBr, LiF, LiI, Kcl, MgCl2, or MgI. Halide salts of other metals as well
as ammonium and metal nitrates, nitrites, sulfates, sulfites, phosphates, phosphites,
borates, and carbonates can be used, for example Na2SO4, LiBO2, LiCO3, LiNO2, Li2SO4,
MgSO4,NaNO3, NaNO2, NaPO3, Na2SO3, Al2(SO4)3, or Na3PO4. Hydroxides such as
LiOH, Ba(OH)2, KOH, CsOH, or NaOH can also be used.
The stabilizing agents are added to make from about 0.05 percent by weight up tosaturated solutions in water. Preferably from about 0.1 to 50 percent by weight aqueous
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solutions of stabilizing agents are used to hydrolyze the hydrocarbyl aln.. l
compounds.
The stabilizing agent Cont:~inin~ a~ueous solutions can be combined with the r
hydrocarbyl al---.~ -- compound in an inert organic solvent by any suitable manner such
Sas the various ways which are known in the art. For exarnple, the process which is
described in U.S. Patent No. 4,908,463 where water dispersed in an organic solvent is
mixed with a solution of the hydrocarbyl al-lminl-m in a "T-shaped" reactor. The amount
of water dispersed in the solvent is preferably from about 0.25 to 5.0 weight percent,
based on the weight of solvent. A more preferred amount is about 0.5 to 3.0 weight
10percent and most preferred is about 1.0 to 2.5 weight percent. The r~cts~nt~ are combined
in proportions to provide from about 0.5 to 4.0 moles of hydrocarbyl ahTmin~lm
compound per mole of water and from about 5.0 to 10,000 moles of hydrocarbyl
alnminllm compound per mole of stabilizing agent and, preferably, from about 50 to
5,000 moles of hydrocarbyl alll..lit~l.... compound per mole of stabilizing agent.
The invention is further illustrated by, but is not intended to be limited to, the
following examples.
Fx~mple 1
An aqueous LiCl solution was pl~ed which contained 0.35 pounds (158.9
grams) of anhydrous LiCI salt in 3 gallons (11.36 liters) of solution. This salt solution
was fed into a flow-through sonicating horn at a rate of 0.15 lbs. (68.1 gms) per hour and
~m~ if ied with toluene fed at a rate of 10 pounds (4.54 Kg) per hour. This emulsion was
then reacted with a 12 weight percent trimethylaluminum (TMA) in toluene stream fed
at a rate of 11 pounds (5.38 Kg) per hour. The TMA-to-water mol ratio was 2.2 to 1.
The reaction mixture was then discharged into an eductor, mixed with methylaluminoxane
(MAO) product solution from a pump-around loop, and finally discharged into the vapor
space of a deg~c~ing vessel. The toluene feed to the sonication horn was m~int~ined at
a temperature of -2~C. The TMA feed stream was m~intzlined at a temperature of 5~C.
The f1eg~ing vessel was m~int~ined at a temperature of 20~C.
The crude product was sampled and it was noticed that there was practically no
~leg~in~ in the sample. This behavior is very dirre~ t from that observed for samples
-
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of crude MAO prepared using plain water. Normally crude MAO will continue to degas
for 3 to 4 hours after sampling. The solids formed in the new MAO product also appear
to settle faster than the solids in normal MAO crude.
A sample of the new MAO was taken from the product skeam during the run and
Y S was filtered. The solids produced from the reaction appear to filter easier than those
formed by the standard MAO plain-water process. The filtered crude was then batch
flashed to concentrate the product. The crude product was c~n~ntr~tecl by fl~hing of the
solvent using a 104~C wall temperature, a 60~C bulk t~ cldl~lre, and a vacuurn of 100
mm Hg. The resulting solution was 8.86 weight percent Al. The TMA content of thesolution was 4.84 weight percent TMA. The sample c~nt~in~d less than 20 ppm Cl. The
alllminllm content equates to a 15 weight percent solution of MAO. This 15 weight
percent MAO solution was isolated from the flash pot as a clear liquid.
The increased stability of the new MAO was demonstrated by placing a 15 weight
percent solution in an oven at 60~C for 4 days, along with a 30 weight percent solution of
15 conventional plain-water p,~aled MAO. After the 4 days the MAO was cloudy, but the
new MAO was still clear. The oven ~elll~ldlule was then increased to 65~C for two more
days. The new MAO remained clear. The oven temperature was then raised to 80~C.
After one day at 80~C the new MAO was still clear, but regular MAO was completely
gelled.
After the oven test, the 15 weight percent MAO solution was used in a
polymerization test to clet~rmine if it was active as a co-catalyst. Three mL of the 15
weight percent MAO solution were added to 100 mL of toluene. To this solution, 0.25
mL of a solution of 18 mg of zirconocene dichloride -- (C5H5)2ZrCl2 -- dissolved in 18 rnL
toluene was added. The solution was stirred and heated in an oil bath to 80~C. A constant
pressure of ethylene (60 psig) gas was then placed on the reaction vessel. After 35
minlltes, the vessel was removed firom the oil bath and the pressure was released. The
polyethylene product was collected by filtration, washed and dried. The final yield was
7.05 grams of polyethylene.
The polymerization test was repeated with standard plain-water prepared MAO.
A change was made in the volume of MAO solution added based on the calculated weight
percent MAO. Two mL of 23 weight percent MAO was added to 100 mL of toluene and
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then 0.25 mL of the zirconcene dichloride toluene solution was added. The reaction was
performed under the same conditions for the same length of time as the above
polymeri7~tion test. The polyethylene was collected, washed and dried. The final yield
was 7.88 grams. Allowing for expe~ l error, this result equates to approximately the
S same degree of reactivity as the new MAO which has been heat aged. This demonstrates
that the improved stability of the MAO pl~cd in accordance with the process of the
invention is achieved without loss of activity.
Fxzlmplç 2
MAO was prepared using the sarne I,iCl salt solution as in Example I, but the feed
rates and temperatures were somewhat different.
The salt solution was fed at a rate of 0.16 Ibs (72.6 gms)/hr. The toluene stream
was fed at 11.6 Ibs (5.26 Kg)/hr. The TMA stream was fed at 11.6 Ibs (5.26 Kg)/hr.
These feed rates produced a TMA-to-water mole ratio of 2.22 to I . The temperature of
deg~ing vessel for the second run was m~int~ined at 1 0~C. The other feed t~ Ldtures
were m~in~inP~l the same as in Fx~mple 1.
A sample of the MAO was taken from the second run and was filtered and flashed
under the same conditions as the first run sample of Exarnple 1. The final weight percent
Al of this sample was 11.4. The sample contained 7.96 weight percent TMA and 0.01
weight percent Cl. These results equate to an 18 weight percent MAO solution. This
solution was clear upon leaving the flash pot. A portion of the sample was placed in an
oven at 65~C for two days and it remained clear ang gel free. The oven was then
increased to 80~C, and a sample of standard 10 weight percent MAO was placed in the
oven. After one day the new MAO was still clear, but the 10 weight percent MAO began
turning cloudy.
The solids filtered from the sarnple from Exarnple 2 were analyzed. The solids
contained 11.5 weight percent Al, no detectable TMA, 0.35 weight percent Cl, and a
gas/AI mole ratio of 1.47. This ratio is approximately equivalent to that of standard plain-
water prepared MAO. These results indicate that these solids could be a higher molecular
weight MAO. An experiment was conducted to determine if the solids could be used as
both an activator and a support for a metallocene catalyst. The solid was rinsed from the
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bottle with toluene and collected on a coarse frit. The solids were then washed with
isopentane and a fine white powder resulted. The solid was removed from the frit and
slu}Tied with toluene. S;x mL of a 0.100 gram of zirconocene dichloride dissolved in 60
mL toluene solution was then added to the slurry and the resulting ~ Lu~e ~it~tet1 The
S slurry began t~h~nging color from white to peach colored. After approximately one-half
hour, the slurry was transferred to the coarse frit for filtering. The toluene was filtered
from the solid. The peach-colored solid was then rinsed with isopentane. Upon rinsillg,
the solid turned to a white powder. One-half gram of this solid was placed into a reaction
vessel and 25 mL of toluene was added to produce a slurry. The vessel was then placed
10 in an oil bath at 80~C and the slurrv was stirred at this te~ dLul~. Ethylene was applied
to the vessel at a continuous pressure of 60 psig while being m~int~in~(l at 80~C. After
10 minllte~, the vessel was removed from the oil bath and the pressure on the vessel was
released. The polyethylene produced from this reaction was washed, filtered, and dried.
The final yield of polyethylene was 2.1 grams.
