Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
32~
--1--
ULTRA HIGH EFFICIENCY
CATALYST FOR POLYMERIZING OLEFINS
This invention relates to new catalyst
compositions for polymerization of ~-olefins and to a
polymerization process employing such catalyst
compositions.
It is well known that olefins such as ethy-
lene, propylene and 1-butene in the presence of certain
transition metal catalysts can be polymerized to form
substantially unbranched polymers of relatively high
molecular weight. Typically such polymerizations are
carried out at relatively low temperatures and pressures.
- Among the methods o producing such linear
olefin polymers, some of the most widely utilized are
those described by Professor Karl Ziegler in U.S.
Patents 3,113,115 and 3,257,332. In these methods, the
catalyst employed is obtained by admixing a compound of
a transition metal of Groups IVB, VB, VIB and VIII of
Mendeleev's Periodic Table of Elements with an organo-
metallic compound. Generally, the halides, oxyhalides
and alkoxides or esters of titanium, vanadium and
29,019A-F -1-
.
--2~
zirconium are the most widely used transition metal
compounds. Common examples of the organometallic
compounds include the hydrides, alkyls and haloalkyls
of aluminum, alkylaluminum halides, Grignard reagents,
alkali metal aluminum hydrides, alkali metal borohy-
drides, alkali metal hydrides, alkaline earth me-tal
hydrides and the like. Usually, polymerization is
carried ou-t in a reaction medium comprising an iner-t
organic liquid, e.g. an aliphatic hydrocarbon, and the
aforementioned ca-talyst. One or more olefins may be
brought into contact with the reac-tion medium in any
suitable manner. A molecular weight regulator, which
is normally hydrogen, is usually present in the reaction
vessel in order to suppress the formation of undesirable
high molecular weight polymers.
Most of the aformentioned known catalyst
systems are more efficient in preparing polyolefins in
slurry (i.e., wherein the polymer is not dissolved in
the carrier) than in solution (i.e., wherein the
temperature is high enough to solubilize the polymer in
the carrier). The lower efficiencies of such catalys-ts
in solution polymerization is believed to be caused by
deactivation of such catalysts by the higher temperatures
employed in solution processes. In addition, processes
involving the copolymerization of ethylene with higher
~-olefins exhibit catalyst efficiencies significantly
lower than ethylene homopolymerization processes.
Recently, e.g. British 1,492,379, high
efficiency catalysts have been disclosed which permit
polymerization temperatures above 140C. Such high
polymerization temperatures provide for reduced energy
requirements in solution polymerization processes in
29,019A-F -2-
--3~
that the closer the polymerization temperature is to
the boiling point of the polymerization solvent, the
less energy is required in removing the solvent.
U.S. Paten~s 4,250,286 and 4,269,733 disclose
the preparation of a catalyst for polymeriz.ing olefins
in which the catalyst contains the product resulting
from the admixture of a transition metal compound and
a zinc compoundO
It has now been discovered that such catalyst
can be impro~ed if the transition metal compound is
first mixed with certain oxygen-containing materials
beore addition of the zinc compound. The catalysts
subsequently prepared therefrom have higher initial
rates of reaction and higher efficiencies than do those
catalysts prepared without the oxygen-containing material.
SUMMARY OF THE INVENTION
The present invention is a catalyst for the
polymerization of -olefins under Ziegler polymerization
conditions and comprising a magnesium halide, a transition
metal compound an a zinc compound characterized by first
forming:
(A) a reaction product or complex formed
from the admixture of
(1) a reaction product or complex formed
by mixing
(1.1) at least one transition metal
compound represented by the
empirical formulae Tm(OR)yXx y,
TxOXx_2 or Tm(OR)x-20 wherein
Tm is a transition metal selected
from groups IV~, VB or VIB;
29,019A-F -3-
-3a- 1~9~ 2 ~ ~
each R is independently a
hydrocarbyl group, having from
1 to 20 carbon atoms; each X
is independently a halogen; x
has a value equal to the valence
of Tm and y has a value from 1
to the valence of Tm; and
(1.2) at least one oxygen-contain-
ing compound; and
(2) at least one non-reducing alkylating
agent represented by the empirical
formulae ZnR2 or RZnX wherein X is
a halogen, preferably chlorine or
bromine and each R is independently
an alkyl group having from 1 to 20
carbon atoms; and thereafter
admixing
(B) a magnesium halide resulting from the
reaction of
(1) an organomagnesium compound
represented by the empirical form~la
MgR"2-xMR"y wherein M is aluminum or
zinc, each R" is independently a
hydrocarbyl or hydrocarbyloxy group
having from 1 to 20 carbon atoms,
x has a value from zero to 10 and
y has a value corresponding to
the valence of M; with
(2) a halide source selected from
(2.1) an active non-metallic halide,
said non-metallic halide corres-
ponding to the empirical formula
R'X wherein R' is hydrogen or a
- hydrocarbyl group such that the
hydrocarbyl halide is at least
as ac-tive as sec-butyl chloride
and does not poison the catalyst,
. and X is halogen or
... . .
~`~ 29,019A -3a-
3b-
.
(2.2) a metallic halide correspond-
ing to the empirical formula
MR~ aXa wherein M is a metal
of Group IIIA or IVA of Mendel~
eev's Periodic Table o Elements,
X is a monovalent hydrocarbyl
radical, X is halogen, y is a
number corresponding to the,
valence of M and a is a number
of 1 to y; and
(C) when the organomagnesium component and/or
the halide source provides insufficient
quantities of aluminum, an aluminum
compound is added which is represented
by the empirical formula AlRy,Xy,l wherein
R and X are as defined above and y' and y"
each have a value of from zero to three
with the sum of y' and y" being three;
and
said components are employed in quantities which provide
an atomic ratio of the elements Mg:Tm of from 1:1 to
200:1; Zn:Tm of from 0.1:1 to 10:1; O:Tm of from 0.1:1
to 4 1; Al:Tm of from 0.1:1 to 200:1 and an excess X:Al
of from 0.0005:1 to 5:1.
Another aspect of the presen~ invention is
a process for polymerizing ethylene and other ~-olefins
under Ziegler polymerization conditions in the presence
of a catalyst comprising a magnesium halide, a titanium
compound, and a zinc compound characterized in that the
catalyst is prepared by first forming a reaction product
or complex
(A) of a mixture of a titanium compound of
the formula Ti(OR)4 where R is Cl-C10
alkyl and an alcohol in quantities to
provide an atomic ratio of OoTi of 0.1:1
to 4:1 with an organo zinc compound of
the formula ZnRx wherein R is Cl-C10
29,019A-F -3b-
~3c-
(A) of a mixture of a titanium com~ound of ~he
formula Ti(OR~4 where R ls Cl-C10 alkyl and
an alcohol in quantities to provide an atomic
ratio of O:Ti of 0.1:1 to 4:1 with an
organo zinc compound of the formula ZnR2
wherein R is Cl-C10 alkyl; and thereafter
admi~cing
(B) a magnesium halide resulting from the reaction
of
(1) an organomagnesium compound represented
by the empirical formula MgR"2-xMR"y
wherein M is aluminum or zinc, each R"
is independently a hydrocarbyl or hydro-
carbyloxy group having from 1 to 20
carbon atoms, x has a value from zero to
10 and y has a value corresponding to
the valence of M; with
(2) a halide source selected from
(2.1) an active non-metallic halide,
, said non-metallic halide corres-
ponding to the empirical formula
R'X wherein R' is hydrogen or a
hydrocarbyl group such that the
hydrocarbyl halide is at least as
active as sec-butyl chloride and
does not poison the catalyst, and X
. is halogen or
(2.2) a metallic halide corresponding
to ~he empirical formula MRy aXa
wherein ~ is a metal of Group IIIA
or IVA of Mendeleev's Periodic
Table of Elements, R is a mono-
valent hydrocarbyl radical, X is
halogen, y is a number corres-
ponding to the valence of M and a
is a number of 1 to y; and
29,019A-F -3c-
--4--
(C) when the organomagnesium component and/or
the halide source provides insufficient
quantities of aluminum, an aluminum
compound is added which is represented
by the empirical formula AlRy~Xyl~ wherein R
and X are as defined above and y' and y" each
have a value of from zero to three with the
sum of y' and y" being three; and
said components are employed in quantities which provide
an atomic ratio of the elements Mg:Tm of from 1:1 to
200:1; Zn:Tm of from 0.1:1 to 10:1; O:Tm of from 0.1:1
to 4:1; AloTm of from 0.1:1 to 200:1 and an excess X:Al
of from 000005:1 to 501.
The components are employed in quantities
which provide the composition with atomic ratios of the
elements as follows.
29,010A-~ -4-
2~D
--5--
Mg:Tm is from l:1 -to 200:1, preferably ~rom
2:1 to 100:1 and ~lost preerably from 5:1 -to 75:1.
, Al:Tm is from 0.1:1 to 200:1, preferably from
0.5:1 to 100:1 and most preferably from 1:1 to
75:1.
Excess X:Al is from 0.0005:1 to 5:1, preferably
from 0.002:1 to 2:1 and most preferably from
0.01:1 to 1.4:1.
Excess X is the amount of halide above that
amount which is theoretically required to convert
the organomagnesium component to magnesium dihalide.
The present invention is most advantageously
practiced in a polymerization process wherein an ~-olefin
is polymerized, generally in the presence of hydrogen
as a molecular weight control agent, in a polymerization
zone containing an inert diluent and the catalytic
reaction product as hereinbefore described. Especially
advantageous is the copolymerization of ethylene and
higher ~-olefins using the catalytic reaction product
of this invention. The foregoing polymerization process
is most beneficially carried out undex inert atmosphere
and relatively low pressures, although very high pressures
are optionally employed.
Olefins which are suitably homopolymeri~ed or
copolymerized in the practice of this invention are
generally the aliphatic ~-monoolefins or non-conjugated
~-diolefins having from 2 to 18 carbon atoms. Illustra-
tively, such ~-olefins can include ethylene, propylene,
butene-1, pentene-1, 3-methylbutene~ methylpentene-1,
hexene-1, octene-l, dodecene-1, octadecene-1, 1,7 octadiene,
1,4-hexadiene, and mixtures thereof. It is understood
29,019A-F -5-
2~)
--6--
-that ~-olefins may be copolymerized with other ~-olefins
and/or with small amounts, i.e., up to abou-t 25 weight
perc~nt,based on the polymer, of other ethylenically
unsaturated monomers such as styrene, ~-methylstyrene
S and similar ethylenically unsaturated monomers which do
not destroy conventional Ziegler catalysts. Mos-t
benefits are realized in the polymerization of aliphatic
~-monoolefins, particularly ethylene and mixtures of
ethylene with up to 50, especially from 0.1 to 40,
weight percent of propylene, butene-1, hexene-1, octene-l,
4-methylpentene-1, 1,7-octadiene, 1,4-hexadiene or
similar ~-olefin or non-conjugated ~-diolefins based on
total monomer.
Suitable zinc compounds which can be employed
as the essentially non-reducing alkylating agent are
those represented by the empirical formulae R2Zn or
RZnX wherein each R is independently a hydrocarbyl
group having from l to 20, preferably from 1 to 10,
carbon atoms and X is a halogen, preferably chlorine or
bromine. Particularly suitable zinc compounds include,
for example, diethyl zinc, dimethyl zinc, ethyl zinc
chloride, diphenyl zinc and mixtures thereof.
~ y the term essentially non-reducing it is
meant that simple mixing of the alkylating agent with
the titanium species at normal conditions does not lead
to a reduction in the oxidation state of the titanium
compound.
Suitable non-metallic oxygen-containing
compounds which can be employed herein include, for
example, molecular oxygen, alcohols, ketones, alde-
hydes, carboxylic acids, esters of carboxylic acids,
29,019A-F -6-
--7~
peroxides, and water. Those compounds which are so]uble
in hydrocarbon solvent are especially preferred.
r
Particularly suitable alcohols include, for
example, n-butanol, sec-butanol, iso-propanol, n-pxopanol,
and mixtures -thereof.
Particularaly suitable ketones which can be
employed herein include, for example, acetone, methyl-
ethyl ketone, methyl isobutyl ketone, and mixtures
thereof.
Particularly suitable carboxylic acids which
can be employed herein include, for example, formic
acid, acetic acid, stearic acid, and mixtures thereof.
Particularly suitable ethers which can be
employed include, for example, diethyl ether, ethyl
vinyl ether, and mixtures thereof.
Particularly suitable aldehydes which can be
employed herein include, for example, formalehyde,
acetaldehyde, propionaldehyde, and mixtures thereof.
Particularly suitable peroxides which can be
employed herein include, for example, hydrogen peroxide,
t-butylperoxide, and mixtures thereof.
Suitable transition metal compounds which can
be employed in the present invention include those
represented by the empirical formulae Tm(OR)yXx y ,
Tm(OR)x 2 or TmOXx 2 wherein Tm is a transition metal
selected from groups IVB, VB or VIB; each R is indepen-
dently a hydrocarbyl group, preferably alkyl or aryl,
29,019A-F -7-
312~
having from 1 to 20, preferably from 1 to 10, carbon
atoms; each X is independently a halogen, preferably
chlorin~ or bromine; x has a value equal to the valence
of Tm and y has a value from 1 to the valence of Tm.
Particularly suitable transition metal com-
pounds include for example tetraethoxy titanium, tetra-
isopropoxy titanium, tetra-n-bu-toxy titanium, di-n-butoxy
titanium dichloride, tetraphenoxy titanium, tetra-n-
propoxy titanium, tetra-(2-ethylhexoxy) titanium,
tri-n-butoxy vanadium oxide, oxyvanadium trichloride,
tri-isopropoxy vanadium oxide, zirconium tetra-n-
butoxide, zirconium tetra-n-propoxide, zirconium
tetra-isopropoxide, and mixtures thereof.
Suitable organomagnesium components which can
be ~mployed in the present invention include those
represented by the empirical formula MgR"2-xMR"y wherein
each R" is independently hydrocarbyl or hydrocarbyloxy,
M is aluminum, zinc or mixtures thereof and x is zero
to 10, preferably zero to 5, most preferably from zero
to 2.5; and y denotes the number of hydrocarbyl and/or
hydrocarbyloxy groups which corresponds to the valence
of M. As used herein, hydrocarbyl and hydrocarbyloxy
are monovalent hydrocarbon radicals. Preferably,
hydrocarbyl is alkyl, cycloalkyl, aryl, aralkyl, alkenyl
and similar hydrocarbon radicals having 1 to 20 carbon
atoms, with alkyl having 1 to 10 carbon atoms being
especially preferred. Likewise, preferably, hydro-
carbyloxy is alkoxy, cycloalkyloxy, aryloxy, aralkyloxy,
alkenyloxy and similar oxyhydrocarbon radicals having 1
to 20 carbon atoms, with alkoxy having 1 to 10 carbon
atoms b~ing preferred. Hydrocarbyl is preferred over
hydrocarbyloxy.
29,019A-F -8-
2~1D
`~ g
Preferably the organomagnesium compound is a
hydrocarbon soluble dihydrocarbylmagnesium such as the
magnes~um dialkyls and the magnesium diaryls. Exemplary
suitable ma~nesium dial]~yls include particularly
n-butyl-sec-buty] magnesium, di.isopropyl magnesium,
di-n-hexyl magnesium, isopropyl~n-butyl magnesium,
ethyl-n-hexyl magnesium, ethyl-n-butyl magnesium,
di-n-octyl magnesium and others wherein the alkyl has
from 1 to 20 carbon atoms. Exemplary suitable
magnesium diaryls include diphenylmagnesium, dibenzyl-
magnesium, and ditolylmagnesium. Suitable organo-
magnesium compounds include alkyl and aryl magnesium
alkoxides and aryloxides and aryl and alkyl magnesium
halides with the halogen-free organomagnesium compounds
being more desirable.
Among the halide sources which can be employed
herein are the active non-metallic halides and me-tallic
halides.
Suitable non-metallic halides are represented
by the empirical formula R'X wherein R' is hydrogen or
an active monovalent organic radical and X is a halogen.
Particularly suitable non-metallic halides include, for
example, hydrogen halides and active organic halides
such as t-alkyl halides, allyl halides, benzyl halides
and other active hydrocarbyl halides wherein hydro-
carbyl is as defined hereinbefore. By an active organic
halide is meant a hydrocarbyl halide that contains a
labile halogen at least as active, i.e. as easily lost
to another compound, as the halogen of sec-butyl chloride,
preferably as active as t-butyl chloride. In addition
to the organic monohalides, it is understood that
organic dihalides, trihalides and other polyhalides
29,019A-F -9-
--10--
that are ac-tive as defined hereinbefore are also suit-
ably employed. Examples of preferred active non-
metalli,c halides include hydrogen chloride, hydrogen
bromide, t-butyl chloride, t-amyl bromide, allyl chloride,
benzyl chloride, crotyl chloride, methylvinyl carbinyl
chloride, ~phenylethyl bromide, and diphenyl methyl
chloride. Most preferred are hydrogen chloride, t-butyl
chloride, allyl chloride and benzyl chloride.
Suitable metallic halides which can be employed
herein include those represented by the empirical
formula MRy aXa wherein M is a metal of Groups IIIA or
IVA, of Mendeleev's Periodic Table of Elements, R is a
monovalent organic radical, X is a halogen, y has a
value corresponding to the valence of M and a has a
value from 1 to y. A suitable metallic halide is
SnCl4, although the preferred metallic halides are
aluminum halides of the empirical formula AlR3 aXa
wherein each R is independently hydrocarbyl as herein-
before defined such as alkyl, X is a halogen and a is a
number from 1 to 3. Most preferred are alkylaluminum
halides such as ethylaluminum sesquichloride, diethyl
aluminum chloride, ethylaluminum dichloride, and
diethylaluminum bromide, with e-thylaluminum dichloride
being especially preferred. Alternatively, a metal
halide such as aluminum trichloride or a combination of
aluminum trichloride with an alkyl aluminum halide or a
trialkyl aluminum compound may be suitably employed.
It is understood that the organic moieties of
the aforementioned organomagnesium, e.g. R", and the
organic moieties of the halide source, e.g. R and R',
are suitably any other organic radical provided that
they do not contain functional groups that poison
29,019A-F -10-
conven-tional Ziegler catalysts. Preferably such organic
moieties do not contain active hydrogen, i.e., those
suffici,en-tly active to react with the Zerewi-tinoff
reagen-t.
In preparing the reaction product or complex
of the present invention, the transition metal compo-
nen-t and oxygen-containing component are mixed together
in a sui-table inert solvent or diluent -followed by the
- addi-tion of the alkylating agen-t in a quantity and
under suitable conditions so as to effect a color
change in the reaction mixture. Suitable conditions
include temperatures of from about -50C to 110C,
preferably from 0C to 30C. At lower temperatures,
longer times may be re~uired to effect a color change.
The reaction time is also affected by the
concentration of the reactants, e.g. low concentrations
require longer times at any given temperature than do
higher concentrations. The solvents which can be
employed include those suitable for preparing the
catalysts of this invention with the hydrocarbon sol-
vents being most suitable.
The color change which occurs upon addition
of the essentially non-reducing alkylating agent varies
depending upon the particular components employed, i.e.
the particular oxygen-containing compound and/or the
particular alkylating agent.
The magnesium halide can be preformed from
the organomagnesium compound and the halide source or
it can be prepared in situ in which instance the catalyst
is prepared by mixing in a suitable solvent (1) the
29,019A-F
-12-
organomagnesium component, B-l, (23 the halide source,
B-2 and (3) the reaction product or complex formed by
mixing,(a) a mixtuxe of said -transition metal component
(A-1.1) and said oxygen-containing componen-t (A-1.2)and
(b) said alkylating agent (A-2).
The foregoing catalyst components are com-
bined in proportions sufficient to provide atomic
ratios as previously mentioned.
In cases wherein neither the organomagnesium
component nor the halide source contains aluminum or
contains an insufficient quantity of aluminum, it is
necessary to include in the total catalyst an aluminum
compound such as an alkyl aluminum compound, e.g. a
trialkyl aluminum, an alkyl aluminum halide or an
aluminum halide. If polymerization temperatures below
180C are employed, the atomic ratios of Al:Ti may be
from 0.1:1 to 200:1, preferably from 1:1 to 100:1.
However, when polymerization -temperatures above 180C
are employed, the aluminum compound is used in propor-
tions such that the Mg:Al ratio is more than 0.3:1,preferably from 0.5:1 to 10:1, and Al:Ti ratio is less
than 120:1, preferably less than 50:1. It is understood,
however, that the use of very low amounts of aluminum
necessitates the use of high purity solvents or diluents
in the polymerization zone. Further, other components
present in the zone should be essentially free of
impurities which react with aluminum alkyls. Otherwise,
additional quantities of an organometallic compound as
previously described, preferably an organoaluminum
compound, must be used to react with such impurities.
Moreover, it is understood that in -the catalyst the
aluminum compound should be in the form of trialkyl
29,019A-F -12-
2~L~
~13-
aluminum or alkyl aluminum halide provided that the
alkyl aluminum halide be substantially free of alkyl
alumin~m dihalide. In the above mentioned aluminum
compounds, the alkyl groups independently have from 1
to 20, preferably from 1 to 10, carbon atoms.
When additional quantities of aluminum compound
are employed, it can be added to the aforementioned
catalyst during the preparation -thereof or the aluminum
deficient catalyst can be mixed with the appropriate
aluminum compound prior to entry into the polymeriza-tion
reactor o~, alternatively, the aluminum deficient
catalyst and the aluminum compound can be added to the
polymerization reactor as separate streams or additions.
The foregoing catalytic reaction is prefer-
ably carried out in the presence of an inert diluen-t.
The concentrations of catalyst components are prefer-
ably such that when the essential components of the
catalytic reaction product are combined, the resultant
slurry is from 0.005 to 1.0 molar (moles/liter) with
respect to magnesium. By way of an example of suitable
inert organic diluents can be mentioned liquified
ethane, propane, isobutane, n-butane, n-hexane, the
various isomeric hexanes, isooctane, paraffinic mixtures
of alkanes having from 8 to 12 carbon atoms, cyclohexane,
methylcyclopentane, dimethylcyclohexane, dodecane,
industrial solvents composed of saturated or aromatic
hydrocarbons such as kerosene, naphthas, etc., especially
when freed of any olefin compounds and other impurities,
and especially those having boiling points in the range
from about -50 to 200C. Also included as suitable
inert diluents are benzene, toluene, ethylbenzene,
cumene, decalin and the like.
29,019A-F -13-
-14-
Mixing of the catalyst components to provide
the desired catalytic reaction product is advantageously
carried out under an inert atmosphere such as nitrogen,
argon or other inert gas at temperatures in the range
5 from -100 to 200C, preferably from about 0 to 100C.
The period of mixing is not considered to be critical
as it is found that a sufficient catalyst composi-tion
most of-ten occurs within about 1 minute or less. In
the preparation of the catalytic reaction product, it
is not necessary to separate hydrocarbon soluble
componen-ts from hydrocarbon insoluble components of the
reaction product.
In order to maximize catalyst efficiency, the
catalyst is prepared by mixing the components of the
catalyst in an inert liquid diluent in the following
order: organomagnesium compound, halide source, the
aluminum compound if required, and the reaction product
or complex formed from said transition metal compound,
oxygen-containing compound and alkylating agent. This
is not to imply, however, that other orders of addition
would not result in catalysts having very high
efficiencies.
In the polymerization process employing the
aforementioned catalytic reaction product, polymer-
ization is effected by adding a catalytic amount of theabove catalyst composition to a polymerization zone
containing at least one ~-olefin monomer, or vice
versa. The polymerization zone is maintained at
temperatures in the range from about 0 to 300C,
preferably at solution polymerization temperatures,
e.g., from about 130 to 250C, for a residence time
of a few seconds to several days, preferably 15
29,019A-F -14-
%~ -
-15-
seconds to 2 hours. It is generally desirable to carry
out the polymerization in the absence of moisture and
oxygen,and a catalytic amount of the catalytic reaction
product is generally wi-thin the range from 0.0001 to
o.l millimoles tltanium per liter of diluent. It is
understood, however, that the most advantageous catalyst
concen-tration will depend upon polymerization conditions
such as temperature, pressure, solvent and presence of
catalyst poisons and that the foregoing range is given
to obtain maximum catalyst yields in weight of polymer
per unit weight of titanium. Generally, in the poly-
merization process, a carrier which may be an inert
organic diluent or solvent or excess monomer is employed.
In order to realize the full benefit of the high
efficiency catalyst of the present invention, care must
be taken to avoid oversaturation of the solvent with
polymer. If such saturation occurs before the catalyst
becomes depleted, the full efficiency of the catalys-t
is not realized. For best results, it is preferred
that the amount of polymer in the carrier not exceed
about 50 weight percent based on the total weight of
the reaction mixture.
It is understood that inert diluents employed
in the polymerization recipe are suitably as defined
hereinbefore.
The polymerization pressures preferably
employed are relatively low, e.g., from 0.45-7.09 MPa
(50 to 1000 psig), especially from 0.80-5.00 MPa (100
to 700 psig). However, polymerization within the scope
of the present invention can occur at pressures from
atmospheric up to pressures determined by the capa-
bilities of the polymerization equipment. During
29,019A-F -15-
2~
-16-
polymerization it is desirable to stir the polymerization
recipe to obtain better temperature control and to
mainta1n uniform polymerization mixtures througou-t the
polymerization zone.
In order to optimize catalyst yields in the
polymerization of ethylene, it is preferable to main-
tain an ethylene concentration in -the solven-t in the
range of from 1 to 10 weight percent, most advan-tageously
from 1.2 to 2 weight percent. To achieve this, when an
excess of ethylene is fed into the system, a portion of
the ethylene can be vented.
~ Iydrogen can be employeA in the practice of
this invention to control the molecular weight of the
resultant polymer. For the purpose of this invention,
it is beneficial to employ hydrogen in concentrations
ranging from 0.001 to 1 mole per mole of monomer. The
larger amounts of hydrogen within this range are found
to produce generally lower molecular weight polymers.
It is understood that hydrogen can be added with a
monomer stream to the polymerization vessel or sepa-
rately added to the vessel before, during or after
addition of the monomer to the polymerization vessel,
but during or before the addition of the catalyst.
The monomer or mixture of monomers is con-
tacted with the catalytic reaction product in anyconventional manner, preferably by bringing the cata-
lytic reaction product and monomer together with
intimate agitation provided by suitable stirring or
other means. Agitation can be continued during poly-
merization, or in some instances, the polymerizationcan be allowed to remain unstirred while the polymer-
ization takes place. In the case of more rapid
29,019A-F -16-
-17-
reactions with more active catalysts, means can be
provided for refluxing monomer and solven-t, if any of
the labter is present, in order to remove the heat of
reaction. In any event, adequate means should be
provided for dissipa-ting the exothermic heat of poly-
merization. If desired, the monomer can be brought in
the vapor phase into contact with the catalytic reac-tion
product, in -the presence or absence of liquid ma-terial.
The polymerization can be effected in the batch manner,
or in a continuous manner, such as, for example, by
passing the reaction mixture through an elongated
reaction tube which is contacted externally with suitable
cooling media to maintain the desired reaction temperature,
or by passing the reaction mixture through an equilibrium
overflow reactor or a series of the same.
The polymer is readily recovered from the
polymerization mixture by driving off unreacted monomer
and solvent if any is employed. No further removal of
impurities is required. Thus, a significant advantage
of the present invention is the elimination of the
catalyst residue removal steps. In some instances,
however, it may be desirable to add a small amount of a
catalyst deactivating reagent of the types convention-
ally employed for deactivating Ziegler catalysts. The
resultant polymer is found to contain insignificant
amounts of catalyst residue.
The following examples are given to illustrate
the invention. All percentages are by weight and all
parts are by molar or atomic ratio unless otherwise
indicated.
29,019A-F -17-
L9~
-18-
EXAMPLES 1-10 AND COMPARATIVE EXPERIMENTS A, B AND C
A. Preparation of the Titanium Complexes
, All titanium-alcohol die-thyl zinc complexes
were prepared by simple admixture of the neat tetraiso-
propyl titanate (TiPT) with the neat n-propanol (n-PrOH),
followed by addition of a 15% solution of diethyl zinc
(DEZ) in Isopar~ E (an isoparaEfinic hydrocarbon fraction
having a boiling range of 116C-134C). After development
of a dark, usually greenish color (generally within ~30
minutes), the mixture was diluted to give an overall
titanium concentration of 0.025 molar. The complexes
were then used in catalyst preparations.
B. Preparation of the Catalyst
In a narrow mouth catalyst bottle under an
inert atmosphere was mixed the following components in
the following order:
97.80 ml Isopar~ E
O.80 ml of 0.94 M ethylaluminum dichloride (EADC)
0.80 ml of 0.745 M di-n-hexyl magnesium (as
obtained commercially from Lithium
Corporation of America)
0.60 ml of 0.025 M titanium complex
100.00 ml
Various titanium-n-propanol-diethyl zinc
complexes ~ere employed as shown in examples 1-12 of
Table I. In addition, one catalyst was prepared con-
taining only tetraisopropyl titanate (comparative
experimen-t A) and one catalyst contained a tetraiso-
propyl titaniate diethyl zinc complex (comparative
experiment B), taught in U.S. Patents 4,250,286 and
4,269,733-
29,019A-F -18-
-19
C. Polvmerization
Into a stirred one-gallon batch reactor was
added 2~liters of Isopar~ E, 0.028 MPa (4 psig) of
hydrogen, 1.22 ~Pa (175 psig) of ethylene, and 10 ml
(0.0015 mmoles Ti) of the previously described ca-talysts.
Ethylene pressure was kept constant a-t 1.40 MPa (200
psig) (the solven-t vapor pressure being 0.25 MPa (21
psig)) and the reactor temperature was controlled at
150C. Because of the high initial activities of these
catalysts, an initial exotherm is produced, the size of
which is dependent on catalyst activity (the higher the
exotherm, the higher the initial catalyst activity).
This exotherm can be controlled to some extent by
cooling the reactor with large volumes of air blown
past the reactor. Total reaction time was 30 minutes.
Catalyst efficiencies and exotherms are listed in Table
I.
It is obvious from the data in Table I that
the addition of small quantities of an alcohol followed
by diethyl zinc leads to a large and unèxpected increase
in catalyst activity as evidenced by improved exotherms
and catalyst efficiencies. Not all ratios of Ti :ROH:DEZ
improves catalyst efficiency, however, as large amoun-ts
(5 or greater mole parts) leads to poorer efficiencies.
Also, a point is reached on DEZ where additional DEZ
will not improve catalyst efficiency and may even lower
the observed efficiency. These runs show that the
addition of 1 or 2 alcohols along with 2 or more DEZ
gives the optimum efficiency.
EXAMPLES 11-13
A. Preparation of the Titanium Complexes
Additional complexes were prepared as in
examples 1-10 above, however this time n-butanol or
29,019A-F -19-
-20-
ethanol were employed. After development of the dark
color (green for butanol and blue for ethanol), the
solutio~s were diluted to 0.025 Molar in titanium
concentration.
B. Preparation of the Catalyst
Catalysts were prepared in a manner inden-
tical to that outlined in examples 1-10 above using the
titanium-alcohol-diethyl zinc complex shown in Table I.
C. Polymerization
Polymerization conditions were identical to
those outlined in examples 1-10 above. Catalyst exo-
therms and efficiencies are listed in Table I.
By comparing examples 11 and 5 and examples
12, 13 and 4, it is readily apparent that the type of
alcohol used (i.e., the size of the alkyl group) has
little effect on the catalyst exotherm and efficiency.
EXAMPLES 14-17
A. Preparation of the Titanium Complexes
Complexes were prepared as previously described,
except that n-butanol, acetone and water were used as
the oxygen-contai~ing compounds. The H2O and acetone
mixtures were diluted to 0.025 Molar while the n-butanol
was diluted to 0.0336 Molar, both in titanium.
B. Preparation of the Catalysts
Catalysts were prepared in similar fashion to
examples 1-10 above using the following compounds.
29,019A-F -20-
-21
98.20-x ml of Isopar~ E
0.80 ml of 0.94 M EADC
1.00 ml of 0.60 M n-butyl sec-butyl Mg (obtained
from Lithium Corpora-tion of America)
x ml of y M titanium compound
100.00 ml
where x and y as well as the titanium compound can be
found in the following table:
EXAMPLE x,ml y~ Compound
1014 0.60 0.025 1 TIPT-1 H2O-3 DEZ
0.60 0.0336 1 TiPT-1 BuOH-3 DEZ
16 0.45 0.0336 1 TiPT-1 BuOH-3 DEZ
17 0.60 0.025 1 TiPT 1 acetone-3 DEZ
C. Pol~merization
All polymerizations were conducted at 150C
using 0.13 MPa (19 psig) of hydrogen and 1.12 MPa (160
psig) of ethylene. The length of these runs was 20
minutes. Run results can be found in Table II.
These run results once again show that the
oxygen compound used has little effect on catalyst
efficiency, although it did effect the exotherm in the
case of acetone. In example 15, a lower efficiency
based on titanium resulted from increased titanium
levels in the catalyst even though the initial activity
of the catalyst appeared higher than the others during
the run.
COMPARATIVE EXPERIMENTS D, E AND F
A. PreParation of the Titanium Complexes
A tetraisopropyltitanate-diethyl zinc complex
was prepared by mixing the neat TiPT with the 15% DEZ
29,019A-F -21-
-22-
(1:1 molar ratio). To one aliquot of this solution was
added 1 mole part BuOH. To another ali~uot was added 1
mole pa,rt H2O. All solutions were then diluted to
0.025 M in Ti concentration. These solutlons were then
used to prepare ca-talysts.
B. Preparation of the Catalyst
Catalys-ts were prepaxed in a manner similar
to that previously described in examples 1-10. The
procedure used was:
97.79 ml o 2,2,4-trimethylpentane
0.80 ml of 0.94 M EADC
0.60 ml of 0.025 M ti-tanium complex
1.11 ml of 0.54 M n-butyl-sec-butyl Mg
100.00 ml
The oxygen-containing component employed to
form the titanium complex is shown in Table II.
C. Polymerization
Polymerization was conducted as previously
described using 2,2,4-trimethylpentane as the reaction
solvent and using 0.06 MPa (9 psig) of hydrogen and
0.91 MPa (130 psig) of ethylene for a total pressure of
1.36 MPa (180 psig) (including the 0.39 MPa ~41 psig)
solvent vapor pressure). Results of these runs are
given in Table II.
Comparative experiments E and F show a decrease
in catalyst efficiency as compared to experiment D even
though an oxygen-containing compound and diethyl zinc
have been added. This is due to the order of mixing.
If the diethyl zinc is added to the titanium species, a
29,019A-F -22-
-23~
change of color occurs. If the oxygen-containing
species is then added, an additional color change may
occur ~nd the resulting titanium complex shows a
reduced eEficiency over catalysts made by the preferred
me-thod.
29,019A-F -23-
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