Note: Descriptions are shown in the official language in which they were submitted.
i25~
I t is known that Ziegler~type catalysts formed by combining
an organometallic compound of the metal of Groups IIA, IIs and IIIA
of the Periodic Table with a halide of a metal of Groups IVB, VB
or VIB of the Periodic Table are useful for polymerizing mono-l
olefins at low pressures and low temperatures to form resinous
polyolefins. The Periodic Table referred to herein is published in
Deming, General Chemistry (5th Edition, Wiley, 1944~, and i5
reprinted in Handbook of Chemistry and Physics, p. 336 (31st Edition,
Chem. Rubber, 1949).
~ While many Ziegler-type catalysts are known in the art and
are quite efficient for certain purposes, the ar~ is continuously
seeking new and improved catalysts of this type. In particular, the
art is continuously seeking improved catalysts of lower cost; greater
ease of manufacture and handling; and particularly catalysts of high
activity which leave very low levels of catalyst fragments in the
polymers that are produced~
The present invention provides chemically modified, trans-
ition me~tal chloride compounds that are carried upon a polymeric
support. These products are characterized in containing a rela~ively
low concentration of the t~ansition metal. These products, when
activated by reaction with alumi~um alkyls such as trie~hyl aluminum~
provide highly active ca~alysts for the polymerization of ole~ins
such as ethylene and give very high yields of polymers~ as calculated
on the metal content o~ the catalystu
Thus according to a first aspect of the present invention,
there is provided a process for preparing a supported, chemically-
modified transition metal chloride product useful as a catalyst
component which consists essentially of the sequential steps of:
(a) Suspending a finely-divided polymer in a 1 4 carbon
atom alkanol solution of a magnesium compound,
(b) Vaporizing the alkanol from the suspension of Step
~a) to deposit the magnesium compound, together with the quantity
.~ .
~ ~æ
.
5~
of al~anol which forms a complex therewith, on ~he surface of ~he
finely-divided polymer,
(c) Suspending the product of Step (b) in a liquid hydro-
carbon and adding thereto an aluminum alkyl compound; and
(d) Adding a transition metal chloride compound to the
suspension of Step (c);
the polymer employed in Step (a) being selected from the group
consisting of organic thermoplastic polymers and thermoset polymers,
the particles of such polymer havin~ at least one dimension not
exceeding 600 microns; the magnesium compound employed in Step (a)
having the structure:
MgX2. nH20
where X is Cl, F, Br, I, NO3, OCH3, OCOCH3, or OCOH, and n is not
greater than 6; the magnesium compound employed in Step (a~ con-
sti-tuting 1-60 weight % of the combined weight of the finely~
divided polymer and the magnesium compound; the aluminum alkyl
compound employed in Step (c) being selected from the group con9ist-
ing of dialkyl aluminum hydrides, dialkyl aluminum halides, and
trialkyl aluminums; the quantity of the aluminum alkyl employed in
Step (c) being not in excess of the quantity that will react with
the magnesium compound-alkanol complex carried on the polymer; the
transition metal chloride employed in Step (d) being selected from
the group consisting of titanium tetrachloride and vanadium oxy-
trichloride; and the quantity of the transition metal chloride com- `
pound employed in Step (d) being at least molarly equivalent to the
quantity of the aluminum alkyl compound employed in Step (c).
According to another aspect of the present invention, there
is provided a supported chemically modified transition metal chloride
compound prepared by the aforementioned method.
According to a further aspect of the present invention,
there is provided a process for preparing olefin polymerization
catalyst which consists essentially of reacting an aluminum alkyl
-2a -
~::
,:
compound With a supported, chemically-modified, transition metal
chloride compound prepared according to the aforementioned method,
the aluminum alkyl compound being selected from the group consisting
of dialkyl aluminum hydrides, dialkyl aluminum halides, and
trialkyl aluminums.
In the first step of the preparation of the supported,
chemically-modified, transition metal chloride compounds, a finely
divided polymeric support is suspended in an alkanol solution of a
particular class of magnesium compounds. The polymeric support may
be either an organic thermoplastic polymer or an organic thermostat
polymer. The catalyst support should be in a finely divided
particulate form which has at least one dimension not exceeding
600 mlcrons and preferably having one dimension falling within
_2b -
2~
the range of about 1 to 200 microns. The polymerlc sup~ort ma~ be of any
desired shape such as spheres, rods or cylinders. Suitable polymeric mate-
rials include poly (triallyisocynaurate), polyethylene, pol~propylene, poly
(3-methylbutene) 3 poly (4-methylpentene), polyamides, polyesters, poly-
acrylamides, polyacrylonitriles, polycarbonates and cellulose. Essentially
any polymer not soluble in an alkanol can be employed.
The alkanol solution of a magnesium compound employed in the
treatment o the polymeric support in the first step of the catalyst prepara-
tion wiLl be all alkanol solution of a magnesium compound having the structure:
MgX .nH2O
where X is an anion which imparts solubility of at least 1% ~;
in a lower alkanol (C or less), and n is not greater than 6.
Thus, X can represent Cl, F, Br, I, NO3, OCH3, OCOCH3, or OCOH.
Magnesium compounds found to be particularly suitable in the practice of the
invention include magnesium chloride, magnesium methoxide, magnesium nitrate,
and magnesium acetate. The alkanol in which the magnesium compound will be
dissolved will be an alcohol containing 1-4 carbon atoms such as methanol,
isopropanol, butanol and the like. The alkanol solution should contain a
relatively high concentration of the magnesium compound, e.g., desirably at
least 5% by weight, by reason of the fact that the alkanol subsequently will
be removed from the process by vaporization.
In carrying out the first step of the process, the polymeric sup-
port will be suspended in a sufficient quantity of the alkanol solution of
the magnesium compound so that the magnesium compound contained therein will
constitute 1-60 weight % and preferably 5-25 weight % of the combined weight
of the polymeric support and the magnesium compound. The polymeric carrier
should be stirred with the alkanol solution of the magnesium compound to the
extent required to thoroughly wet and impregnate the polymeric carrier with
the alkanol solution.
2~
In the second s~ep of the process, the alkanol ls vaporized from
the suspension of the polymeric carrier in the alkanol solution so as to
deposit the magnesium compound uniformly over the polymeric carrier. The
magnesium compound is deposited on the carrier in the form of a complex
with tlle alkanol. The precise structure of the complex has not been
established, but it is believed to contain 1 - 4 mols of alkanol per mol
of magnesium compound. It is observed, however, that the magnesium compound-
alkanol complex is in a highly active state ~articularly suitable for use
in the preparation of the chemically-modified, transition metal chloride
compounds in the subsequent steps of the process. To the extent that is
practically feasible, all of the alkanol, except that complexed with the
magnesium compound, should be removed as any excess alkanol will react with
and consume the aluminum alkyl compound employed in the next step of the
process.
The alkanol can be removed by simply distilling or evaporating
the alkanol from the suspension of the polymeric carrier in the alkanol
solution. When this technique is employed, the distillation or evaporation
is preferably carried out under reduced pressure. Frequently the distilla-
tion or evaporation of the alkanol will be accelerated by passing an inert
sweep gas such as nitrogen or argon over the surface of the alkanol solution.
Csre shou].d be exercised to remove the alkanol solution at moderate tempera-
tures not exceeding 150C. and preferably not exceeding 75C. ~len a sweep
gas is employed, special precautions should be employed to free the sweep
gas of water, oxygen and other components recognized as having a dele-
terious effect upon Ziegler-type catalysts.
While a simple evaporation or distillation as described above may
be used to remove the alkanol, somewhat better results are obtained if at
least the final portions of the alkanol are removed by codistillation
with an inert hydrocarbon. In this procedure, after a portion of the
alkanol is removed as described previously, a liquid hydrocarbon such as
heptane, or the like will be added to the reaction vessel. The hydrocarbon
then will be distilled from the system under atmospheric or preferably
2~
reduced pressure. So long as any free uncomplexed alkanol remains in the
system, the distillate being removed from the system will be a mixture
of the hydrocarbon and alkanol. When the final traces of the uncomplexed
alkanol are removed from the system, ~he vapor temperature of the distillate
will rise to the boiling point of the hydrocarbon at the prevailing pressure
employed in the distillation. Thus, the observed boiling point of the dis-
tillate serves as a criterion for determining when the removal of the alkanol
is completed.
The hydrocarbon employed for removal of the alkanol may be of any
of the hydrocarbon types conventionally employed in the preparation of
Ziegler-type catalysts. The hydrocarbon employed should be purified in a
manner so as to remove therefrom moisture and other materials known to have
~eleterious effect upon the activity of Ziegler-type catalysts.
In the next step of the process, the polymeric carrier with the
magnesium compound deposited thereon will be suspended in a liquid hydro-
carbon of the type previously described. Normally, such a slurry already
will have been prepared, particularly where the final traces of the alkanol
are removed by azeotropic distillation as described immediately above. A
suitable aluminum alkyl compound such as diethyl aluminum chloride then
will be added to the slurry. The aluminum alkyl reacts with the magnesium
compound-alkanol complex carried on the polymeric support. The mechanism
by which the two components react and the structure of the resulting
reaction product have not been fully established. The evidence that a chem-
ical reaction takes place is that a gas, possibly an alkane, is formed
when the aluminum alkyl is added to the reaction mixture. The reaction
product formed in this step of the process is firmly bonded to the poly-
meric support.
The aluminum alkyl employed in the step of the process described
immediately above may be a dialkyl aluminum halide, a dlalkyl aluminum
hydride, or a trialkyl aluminum. Typical examples of suitable alkyl alumi-
nums include triethyl alurninum, triisobutyl aluminum, diethyl aluminum
hydride and diethyl aluminum chloride.
The aluminum alkyl should be employed in a quantity suctl that all
of the aluminum alkyl added to the reaction mixture will react with the
magnesium compound-alkanol complex carried on the polymeric support and so
that the reaction system, after completion of this step of tlle process, con-
tains little or no unreacted aluminum alky] in the hydrocarbon phase of the
reaction mixture. If an excess of the aluminum alkyl is employed, the remaining
free unreacted aluminum alkyl will react with the transition metal chloride
employed in the next step of the process to form a more conventional Ziegler-
type catalyst as a coproduct. Tlle presencc of such conventional Ziegler-
type catalyst will tend to minimize the advantages obtained with the presentinvention.
The precise quantity of the aluminum alkyl to be employed will be
somewhat dependent upon the completeness with which uncomplexed alkanol is
removed from earlier steps of the process. This results from the fact that
any free uncomplexed alkanol present in the reaction system will react with
the aluminum alkyl compound. Ordinarily, the applicants prefer to employ
approximately 0.1 - 2.0 mols and preferably about 0.25 - 0.5 mol of the
aluminum alkyl for each mol of the magnesium compound present in the reaction
system. If desired or believed to be necessary, the presence of unreacted
aluminum alkyl can be determined either qualitatively or quantitive]y by
removing a sample from the reaction system; filtering the solids from the
slurry and measuring the concentration (if any) of the aluminum alkyl
present in the hydrocarbon filtrate. Analytical methods for measuring the
concentration of aluminum alkyls in hydrocarbons are known in the art.
The use of ]ess than the stoichiometrically required quantity of
the alkyl aluminum has no serious effect upon the quality of the ultimate
product. If the supported reaction product contains unreacted magnesium
compound, the unreacted magnesium compound will react with the transition
metal chloride in the next step of the process to provide a reactlon product
which will be converted into a slightly different polymerization catalyst in
subsequent processing steps.
.~__ _ . . -- , .. _ . . . . , , ..... ... . . _ .. _ _. . _ ._ _ __ _
2~3~
In the next step of the process, a transition metal chloride of
the group consisting of titanium tetrachloride ~nd vanadium oxytrichlorlde
is added to the reaction mixture of the previous step, which contains as
the active reactant the reaction product formed between the supported mag-
nesium compound-alkanol complex and the aluminum alkyl. The transition
met~l chloride reacts with the previously prepared reaction product and is
reduced to a lower valence state. This supported, chemically-modified,
transition ~etal cl1loride compound is the ultimately desired product and
is inso1uble in the hydrocarbon reaction medium. The structure of product
has not been established, but probably is complex. Virtually all of the
titanium becomes bound to the polymeric support, probably by reason of
formation oE a chemical or physical complex with the magnesium compound.
In this step of the process, from about l to 2 mols of the
transition metal chloride will be employed ~or each mol of aluminum alkyl
employed in the previous step of the process. Not more than 2 mols of the
transition metal chloride compound can be reduced by l mol of the previously~
prepared reaction product, and any quantity of transition metal chloride added
in excess of this quantity serves principally to drive the reaction to com-
pletion in the shortest possible period of time.
~s the supported, chemically-modified, transition metal chloride
product is insoluble in tne hydrocarbon medium, it can be recovered by fil-
tration and stored for future use if desired. If the product is recovered
in this manner for storage, the hydrocarbon filtrate containing unconsumed
transition metal chloride can be recovered and reused in the subsequent pro-
duction of additional product. The recovered solid reaction product should
be washed with hydrocarbon to free it from any occluded unreacted transition
metal chloride compound.
It is frequently desirable, however, to use the supported, chemically-
modified, transition metal chloride product shortly after it is prepared. In
such situations, it is usually desirable to employ tlle product in the slurry
in which it is prepared. In such situations, it is desirable to remove
_ . .
any unreacted transitlon metal chloride from the system. Such removal can
be effected by simply distilling the high boiling hydrocarbon from the
slurry at either atmospheric or reduced pressure. The unreacted transltion
metal chloride codis~iLls wlth the hydrocarbon. 'rlle distiLLatLon is ~ontinued
until the distillate gives a negative test Eor chloride.
To prepare catalyst compositions used for the polymeri~ation of
olefins; the supported, chemically-modified ~ransition mctal chlori(le
product is reacted with an aluminum alkyl compound in a hydrocarbon medium.
The reaction is carried out in a manner generally equiva]ent to that employed
1() to prepare more conventional Ziegler-type catalysts. The supported,
chemically-modified, transition metal chloride product is employed Ln the
same molar proportions as conventional transition metal chlorides are
employed in their reactions with aluminum alkyls. Typically the two com-
ponents are employed in proportions to provide an Al/Ti atomic ratio of
about 0.5 - 10.0, or preferably 1.0 - 5Ø While dialkyl aluminum hydrides
an~ dialkyl aluminum halides can be employcd for this purpo.se, the trialkyl
alllmillums, and partlcularly trlethyl nlllmlnum and triisobutyl aLumLnum, are
the preferred aluminum alkyls to be employed in the preparation of such
catalyst compositions.
The polymeri~ation catalysts prepared as described above have a
number of features which make them particularly effective and desirable for
use in the polymeri~ation of mono--l olefins. Initially, it will be noted
that tlle magnesium compound, the transition metal compound, and the aluminum
alkyl compounds are employed in the precise quantities* required in the final
catalyst composition. Thus, no expensive compounds are employed in excess
of their actual need, and the expense of recycling and/or recovering excess
startlng materials are avoided. Tllese factors, coupled with the high pro-
ductivity rates of the catalysts, provide low production costs for the
* The transition metal chloride may be employed in slight excess of that
stoichiometrically required for reasons previously discussed.
r
: ~ . , .. .. .~
polymers produced In addition, b~ ~eason of the high catalyst
productivities, the finished polymers conta~n very low concen-
trations of ~etall~c cataly-st res~dues so that for most purposes
the~ need not ~e removed fro~ ~he polymers. Yet anothe.r advantage
o~ the catalysts of the ~nvent~on is that they have a specific
gravity su~stantially the same as the hydrocarbon solvent
employed in the olefin polymerization process~ Thus, a uniform
disperson of the polymerization catalyst in the polymerization . ... -;
solvent is more easily obtained than is the case with more
conventional Ziegler-type catalyst$.
The catalyst compos;tl~o~s of this invention can ~e
employed in the polymerization of ~ono-l olefins having from 2 to
8 carbon .atoms per molecule. Although not limited thereto, the
novel catalysts are particularly efect;ve in the polymerization
of ethylene to produce polyethylene and in the copolymerization of
ethylene ~ith other mono-l ole~ins containing from 3 to 8 carbon
atoms
The polymerizations can ~e effected with such catalys~s
by contacting the mono-l olefin wîth the catalysts in the liquid
or gaseous phase, and in the presence or absence of an inert
solvent such as ~enzene, xylene, or saturated hydrocar~ons such as
isooctane, n-decane, n-hexane, n-heptane, pentane, decane or
cyclohexane. The concentration of the catalyst composition in the
polymerization zone is maintained in the range of 0.01 to 4.0 g.
per liter of reactor volume. The polymerization reaction is
generally conducted at a temperature of ahout 0 - 250~C. and at a
presure of a~out atmospheric or h~er.
The polymerization process ca~ be conducted batchw.ise,
or ~y continuous polymerization methods known in the art. ~he
polymerization process empolying the novel catalyst composit.;ons
g _
.
~.~9~
can be conducted ~n the a~sence oX presence of hydxogen and other
polymerization add~t~ves and~ox modif~ers known in the art~ such
as amines, ethers or dicumyl perox~de. T~e additives can ~e
introduced onto the catalyst support prior to, during, or after
treatment o~ the support with the transit~on metal chloride
compound. It is also within t~e scope of t~e inventîon to intro-
duce the additive directly into the polymerization re~ctor.
T~e effluent m~xture withdrawn from the polymerization
mixture comprises a polymer s~urr~ which can ~e filtered to iso-
late the resinous polyolefin. Other con~entional polymer separa-
tion steps can ~e employed in the Separation of t~e polymer
product ~rom the remainder o~ the polymerization reactor effluent.
If desired, althou~h not normall~ required ~ecause of
high productivity of the reaction, ~atalyst residues can be
separated from the polymer product ~ method$ known in t~e art. -~
One method comprises stirring a slurr~ of the polymer;zation
product in ~ater or an alcohol such as methanol and then
separating the resinous polyolefin b~ filtration to provide a
white product. Polyolefins which are solu~le in the reaction
solvent can Da precipitated from the solvent by adding an excess
of methanol and filtering off precipitated polymer.
~ ith the catalysts of the invention, a productivity of
at least 10,a00 gran of polymer per gram of titanium per hour is
normally obtained for olefin polymer products having molecular
weights ranging from 20,000 to 2,000,000. These high productiv-
ities of the catalyst compositions eliminate the necessity in most
instances for separating the very small catalyst residues
remaining in the polymer product~
The following examples are presented to illustrate the
principle and practice of the invention. It is not intended,
- 10 --
.
however, t~ lim~t thc invention to th~ $peci~ic em~odiments
presented therein
Exampl~ 3
Three catalyst components wexe ~re~ared following the "`
techniques of the present ;nvent~on a~d were emplo~ed to polymer-
ize ethylene.
Preparat;~oh of S~pport
A 4-liter reaction vessel; fitted w~th a st~r~er, a
reflux condenser, a dropping funnel, and heating and cooliny means
was charged with a methanollc solutlon of magnesium chlor~de
prepared K~ dissolving 75 grams of magnesium chloride in 1 liter
of methanol. Six hundred sevent~ trams o a finely divided powder
of high dens;ty polyethylene having an average particle diameter
of less than 40 microns was slurried in the methanol~c solution o~
magnesium chloride. The slurry-was heated to a temperature of
55C. over a period of 30 minutes and stirring at this temperature
was continued for another 30 minutes~ This pressure then was
reduced to a~out 10 mm of Hg to remove methanol from the system.
-Heating was continued for two hours under these condit:Lons to
2Q assure removal of all methanol which did not form a complex with
the magnesium chloride deposited on the polyethylene su~port. The
powder was removed from the reaction vessel and ground to pass
through a 40-mesh U.S. screen.
Treatment of Support with Diethyl Aluminum Chloride
and TiCl4
._ .. . . . . _~ .
The magnesi~n chloride treated polyethylene powder pre-
pared as described above in the amount of 200 gralnS~ an appropri~
ate quantity of heptane, and an appropriate quantity of diethyl
alumin~n chloride~ was charyed to a 4-liter reactor equipped as
described above. This reactlon mixture was stirred for one hour
while maintaining the temperature at 25~. Evolution of a gas was
~Q9~
noted. ~t th~s point in the reaction, ~t ~.s ~elieved that the
chargea diet~yl aluminu~ chlo~ide has ~een chemicall~ ~onded to
the polymer~c support or one of the chemicals carred t~ereon.
The reaction mixture then was heated to 8~C. and an appropriate
quantity of TiC14 ~as added to the reaction mixture from the
dropping funnel over a period of on~ hour. The reaction mixture
then wa~ st;rred for an add~t~on~l 16-2~ houxs~ while maintaining
the temperature at 80C. to as~sure complete reaction ~etween the
TiC14 and the components carr~ed on the support. Prior to the
addition of the TiC14, t~e solids ~resent ~n the slurry were light
yellow in colorl ~ut the color changed to a purple-red shortly
after the addition of the TiC14. Thè l~quid present in the slurry
was removed by decantation, and the solids ~ère washed with
several aliquots of heptane until t~e ~eptane gave no test for the
presence of chlorides. The solid~ then were recovered and dr.i~d
und~r vacuum at am~ient temperatu~e.
Eth~lene ~ol~merizatîon
The catalyst components prepared as descri~ed a~ove were
employed to polymerize eth~lene i`~ a 1.5 liter pressure resistant
reactor, e~uipped with a stirrer and means for feeding ethylene to
the reactor. After purginy the reactor t~ice wîth polymerization
grade ethylene to remove oxygen, the reactor was charged with 1
liter of heptane, 0.5 gram o the solid catalyst component, and
2 ml. of a 25% solution of triethyl aluminum in heptane. Twenty
grams of polyethylene cubes ~approxLmately 1/8" in diameter3 were
added to the ractor to prevent the polyethylene being produced
from agglomerating and to prevent fouling of the reactor. Poly-
merization grade ethylene was charged to the reactor to develop a
pressure of 40 psig and the ethylene feed system was set to
continuously feed ethylene to the reactor to maintain this pressure.
- 12 -
The reaction mixture ~as heated to a ~emperature o~ 80C. which
initia~ed rap~d polymerization~ Polymerization was continued ~or
a per~od suff~cient to produce approxlmatelY 15~ grams oE polymer~
Polymexizat~on was term~nated fi~ shutting off the supply of
ethylene gas and venting the reactor.
In all o~ the procedures degcri~ed above, care was
exercised to carr~ out all reactions un~er rigorously anhydrous
conditions. All reactants employed were purified grade~ and
contained no identi~iahle concentratlons o~ water or reactive
hydrogen compounds known to have a de~eterlous effect upon
Ziegler-type polymeri~ation reactions.
- 12~ -
Table I below sets forth the quantity of reactants employed in
the preparation of the catal.yst components and also sets forth an
anal.ysis of the u1timate catalyst components. Table It sets fo~th the
polymeri2ation data.
~ . _
- '. ' ~
2~;~
TAUI,~ 1
_ tloll ~
ara~ion of ~l~rport
~ Lhan~l-M~175 1 n
Example Polyethylene Methanol M~C12
No. P~wderL_~ms ml gms _
l 666 1,000 75
2 666 l,U~ 75
3 666 ].,~OU 75
~ - Section B
Preparation of Catal~st Component
Example Catalyst Heptane DEAC (1) TiCL4
No. ~port, gms ml _ m.s__ ~ms
1 200 400 72 663
2 200 300 36 345
3 200 300 36 345
Section C
Catalyst Ana_ysis . _
. - Total
Example Magnesium ; ~luminum Chlorine Titanium Inorganic
No wt_70 _ wt %_wt 7_ _ wt % wt 7.
1 1.7 0.3 9.7 2.0 13.7
2 2.0 4.1lS.9 --, 2.6 24.$
3 1.7 2.7 15.. 1 2.8 22.3
-14-
~9~
~. ,~ ~ ~
o ~cn
~rl ~ ` ~ ` a)
E~ ~u~ ocn Q.
I _
\' tn s~ '
~: ~ o
$
~`
o o o
~: ~g CO o ~ U~
.
o _
,~ ~ O oo ,1 ~r ~d
~: ~ t,
.~ ~o
~o V
. . ~ ~
hId O
_o ~ ~
1~ ~1u~ O LO O
H l ~ $
~ a~
~:
~: ~~o
d ~ .
o~
~3 ~oo ~ ~ ~ ~ 4~
O O O
O
O U~
~ O
N ~:
rl~rl
~ ~ ~ O O O
E~ ` Ql Q
0-~ ~0 ~0 ~0
~1 . h
x æ ~
-- 15 -
~,,` "'
ZSl
Comparative Examples 4-9
For comparison purposes, five catalyst compositions were pre-
pared from reactants simiLar to those employed in Examples 1-3 and were
employed to polymerize ethylene.
The initial catalyst components were prepared by techniques
essentially similar to those described above, except that where a poly-
ethylene support was employed it was not impregnated with magnesium chlo-
ride deposited thereon by evaporation from a methanol solution.
~ The catalyst component of comparative Example 4 was prepared by
mixing 1.4 grams of diethyl aluminum chloride with 6 ml of heptane and
addlng 17.3 grams of TiC14 thereto.
The catalyst component of comparative Example 5 was prepared by
suspending 200 grams of polyethylene powder and 33.8 grams of diethyl
aluminum chloride in 300 ml of heptane and adding 340 grams of TiC14
thereto.
The catalyst component of comparative Example 6 was prepared by
suspending 200 grams of polyethylene powder, 10.6 grams of diethyl aluminum
chloride and 26.8 grams of diethyl aluminum ethoxide in 250 ml of heptane
before adding 345 grams of TiC14 thereto.
The catalyst component of comparative Example 7 was prepared by
adding 200 grams of polyethylene powder, 33.5 grams of diethyl aluminum
chloride and 23.7 grams of methanol to 300 ml of heptane, before adding
345 grams of TiC14 thereto.
The catalyst component of comparative Example 8 was prepared by
adding 200 grams of polyethylene powder, 33.5 grams of diethyl aluminum
chloride and 18.7 grams of magnesium chloride to 300 ml of heptane. The
magnesium chloride was dry-mi~ed with the polyethy~ene powder and added to
the heptane solution before the diethyl a]uminum chloride was added thereto.
Thereafter 345 grams of TLC14 was added to the reaction mi~ture.
_ L~,_
.. _ .. . . .. . ... .. . . . .
~ . ,
The above-described catalyst components were prepared in the
same equipment employed in Examples 1-3 The same heating cycle was
employed :for the reaction of TiC14, and the solid ~a~a~y;st-component was
washed and recovered in the same manner as the catalyst components of
Examples 1-3~ Polymerization catalysts were prepared from these catalyst
components in the same manner described in Examples 1-3 by adding 0.5 gram
of the solid catalyst component and 2 ml of 25% solution of triethyl
aluminum in heptane to 1 liter of heptane. An additional catalyst
(comparative Example 9) was prepared in the same manner, employing 0.5
gram of an aluminum reduced TiC13 in lieu of the experimentally-prepared
catalyst components. The catalysts then were employed to polymerize ethy-
lene as set forth in Examples 1-3.
The chemical analysis of the catalyst components prepared in
comparative Examples 4-9 are set forth in Table III. The polymerization
data obtained in comparative Examples 4-9 are set forth in Table IV.
... ., . . . ~
TABI,~ III
. Catalyst A~alysis Total
Example MagnesiumAluminum Chlorine Titanium Inorganic
No. Wt % Wt % wt % wt % wt %
_
4 - 7.] 58.8 19.2 85.1
- 2.0 23.3 ~3.3 33.6
6 - 0.7 18.4 10.0 29.1
7 - 2.0 11.0 5.7 18.7
8 ~ 1.6 2.3 27.6 7.7 39.2
9 ~ ) - 4.5 7].. 5 24.0 100.0
(1) Calculated from published formula ~iC13 -1/3 AlC13
-18-
TABLE IV
Catalyst Activity
Example Polymerization Polymer Yield g/g-cat/hour g/g-inorgjhour g/g-Ti/hour
No.Time, minutes grams (1) (2) (3)
. .
4 15 60 480 56~ 2500
69 138 410 1698
6 30 138 552 1896 5517
7 30 96 384 2053 6735
8 15 55 440 1122 5712
9 15 46 3608 368 1533
(l) Grams of polymer per gram of catalyst per hour.
(2~ Grams of polymer per gram of inorganic material contalned in the catalyst
per hour.
(3) Grams of polymer per gram of titanium contained in the catalyst per hour.
--19--
From the data o~ Table II it will be noted that the produc-
tivity of the catalysts of the invention is high; the catal~st providing a
minimum of 1500 grams of po~ymer per gram of catalyst per hour and in
one instance a yield of better than 2500 grams of polymer per gram of
catalyst per hour. In addi~ion to providing a high productivity of polymer
the catalyst also provided polymers having an extremely low concentration
of inorganlc catalyst residues inasmuch as the catalyst compositions pro-
viie a po.lymer yield in excess of 8 000 grams of polymer per gram o
inorganic material per hour. The yield of polyethylene based on the
titanium content exceeded 75 000 grams of polye~hylene per gram of ti-
tanium per hour.
By comparison the data of Table IV lndicate that signiiicantly
lower productivity rates are obtained when any departure is made from the
precise mode of preparing tlle catalyst compositions of the invention. The
maximum yield of polymer obtained in the comparative examples was less
than 600 grams of polymer per gram of catalyst per hour. The maximum yield
of polymer per gram of inorganic material was just in excess of 2 000 grams
of polymer per gram of inorganic material.
Example 10
~ polymerization catalyst was prepared by suspending 0.2 gram
of the catalyst component of Example 1 in 50 ml of heptane and adding
thereto 0.36 gram of triethyl aluminum (added as a 25% solution in heptane).
This catalyst mixture then was cooled to approximately 10C. and ethylene
at atmospheric pressure was bubbled through the catalyst suspension. It
was noted that the suspended catalyst solids appeared to grow in size
probably by reason of polymerization o~ ethylene on the catalyst particles.
The ethylene polymeriæation reactor lescribel in rxample I was
purged twice with polymerization grade ethylene to remo-ve oxygen and the
reactor then was charged with 1 liter of heptane. The catalyst suspension
described in the paragraph above then was added to the polymerization
reactor. Polymerization grade ethylene then was charged to the reactor
to develop a pressure of 40 psig and the ethylene feed system was set to
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Z~'~
continuously feed ethylene to the reactor to mainta~n thIs
pressure. The reaction mixtur~ was heated to 80~C. and ~olymer-
izat~on ~a~ continued for one hour. ~ yield of 1,633 ~rams of
polymer per gram of catalyst per hour wa~ obtained.
The catalyst employed ~n this Example 10 differed from
the catalyst of Example 1 in that it was aged briefl~ in the
presence of eth~lene at lo~ temp~rature and atmospher~c pressure
prior to being employed in polymerizing ethylene at elevated
temperature and pressure. ~or reasons not fully understood, this
preliminar~ aging treatment significan-tly modifies the properties
o the polyeth~lene produced ~Ith the ~atalyst. The polymer
particles produced during the polymerization reactîon had a higher
density, were easier to handlet and h~d less tendency to foul the
reactor ~ith low-hulk density pol~mex.
In preparing modified cata~ysts of the type illustrated
in Example 10, ethylene gas is passed in contact with the polymer-
ization catalyst Por a short period of time, usually from about 1
to a~out 5 minutes. The contact is made at ambient temperature
of 20C. or le~s, e.g. 10-15C. being adequate. The contact is
made at substantially atmospheric pressure, although moderately
higher or lower pressures can be employed, e.g. a~out 0~5-l.S
atmospheres. After this pretreatment step, the cakalysts are
employed to polymerize ethylene at more elevated temperatures and
pressures. The principal advantage of this tvpe of pretreated
catal~st and its method of use is that the ethylene polymer pro-
duced has a higher bulk densit~ and a reduced kendency to foul the
polymerization reactor.
Example II
Sixty-seven grams of high density polyethylene, having a
part~cle size less than 40 microns, was suspended in 100 ml of
21 -
Z5~L
methanol containing 7.5 grams of dissolved magn~sium chloride in
a l-liter reaction vessel equipped ~s~descrî~ed in Example l~ Two
hundred fifty ml of heptane then ~as added to the reactor and
the reaction mixture ~as heated to
- 21~ -
t !~
.
2~L
take off an overhead fraction having a boiling point of 59-60C. After
about 175 ml of distillate was recovered, the temperature of the dis-
tillate rose to the atmospheric boiling point of heptane.
The reactor was cooled to room temperature and 70 ml of a
heptane solution containing 12.7 grams of diethyl aluminum chloride was
added to the reactor dropwise over a period of 15 minutes. A colorless
gas was liberated and vented dur-ing this addition. Thereafter, the
reaction mixture was heated to 80C. and 138 grams of TiC14 was added
dropwise to the reaction system. At the start of the addition of the
TiCl~ the reaction mixture was a straw yellow in color, but about 15
minutes aEter the ad~ition of the TiC14 had been completed, the solids
in the reaction system changed to a purpoe-red color. Ileating was con-
tinuecl with stirring for another 16 hours. Thereafter the reactor was
cooled and the catalyst solids were recovered by filtration. The re-
covered solids were washed with aliquots of dry heptane until the wash
heptane gave a negative test for soluble chlorides.
~ total of 0.2 gram of catalyst component described in the para-
graph above was suspended in 50 ml of heptane having dissolved therein 0.36
gram of triethyl aluminum. This suspension was cooled to 10-15C. and
ethylene at atmospheric pressure was bubbled through the catalyst suspen-
sion for 2 minutes~ As in Example 10 above, the catalyst solids appeared
to increase in size, probably by reason of the formation of polyethylene
on the catalyst particles.
The catalyst suspension described in the paragraph above was
added to lO00 ml of heptane and was employed to polymerize ethylene at a
temperature of 85C. and at an ethylene pressure of 40 psig. A total of
242 grams of polyethylene was produced in 1 hour. The yield was 1210 grams
of polymer per gram of catalyst per hour.
-22-
.
Examples 12-15
Four additional catalyst components were prep~red b~ the tech-
nique described in Example 11. The quantities of magnesium chloride,
diethyl eluminum chloride and TiC14 were varied to illustrate the effect
that the ratios of ~he individual chemicals have upon the activity of the
catalyst component and the finished catalyst ultimately formed by react-
ing the catalyst component with triethyl aluminum. Each of the catalyst
components was converted to a finished catalyst by reaction with triethyl
aluminum in the same manner set forth in Example 11. Each of the finished
catalysts was glven a preliminary treatment with ethylene at atmospheric
pressure and at about 15C. for a period of two minutes before being
employed to polymeri7.e ethylene. The catalysts then were employed to
polymerize ethylene at 85C. under a pressure of 4 atmospheres as pre-
viously described. Details of the quantities of the chemicals employed to
prepare the catalyst components are set forth in Table V. The polymeri-
cation results are set forth in Table VI.
l~ABL~ V
Chemicals Used ln Preparation of
Catalyst Component
Example Polyethylene Methanol~IgC12 DE~C (1) TiC1
No. Powder, ~ms ml ~ ms gms
12 666 1,000 72 72 663
13 666 l,OOO 38 36 332
14 666 1,000 38 18 166
666 1,000 38 7 332
(1) Diethyl Aluminum Chloride
. - .
. ., .:
TABLE VI
Catalyst Activity
Example g/g-cat/hour
No. (1)
12 3,000
13 455
14 137
lS . 305
~1) Grams of polymer per gram of catalyst per ho~r.
25~
Althougil the invention has been described w.ith reference to
spec.ific materials, embodiments, and details; various modiflcations and
changes within the scope of this invention will be apparent to one skilled
in the art and are contemplated with being embraced within the scope of
the invention.
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