Note: Descriptions are shown in the official language in which they were submitted.
British Patent 1,372,116 Gulf Research and Development
Co., published October 30, 1974 on an appli.cation filed October
27, 1972 describes the preparation of fibre-like materials
suitable for use in manufacture of waterlaid ~heets. Such
products are prepared from high molecular weight eth~lene polymers
and are referred to as fibrils. In the preparation of such fibrils the
high molecular wei~ht ethylene polymer, having an inherent viscosity
of at least 3.5, is dissolved in a hydrocarbon at a temperature of at
least about 130C and is the starting material from which such fibrils
are prepared.
The preparation of such ethylene polymer solutions presents
technical problems. By reason of the very high molecular weight of the
ethylene polymers employed in the process, such polymer solutions have
high viscosities, even at low concentrations of the ethylene polymer.
The hi~h viscosities of such polymer solutions makes it difficult to
provide adequate stirrin~ to dissolve all of the ethylene polymer par-
ticles. This presents serious problems in that it also has been observed
that the quality of the ultimately-obtained fibrils is adversely
affected, if undissolved polymer solids are present in the ethylene polymer
solution employed in the process.
The preparation of such ethylene polymer solutions is costly
and energy-lntensive in that very large quantities of the hydrocarbon
solvent are required to dissolve the ethylene polymer. Typically, 96
parts by ~eight of hydrocarbon solvent are required to dissolve four
parts by weight of the ethylene polymer. In the preparation of the
fibrils, the heated polymer solution is subsequently cooled to precipi-
tate the ethyle~e pol~mer therefro~. Upon recycling, the hydr~carbon
then must be reheated
In vie~ of 2:he considerations noted above, it would appear to
be desirable to prepare a hot hydrocarbon solution of an ethylene polymer
~y polymerizin~ ethylene in the hydrocarbon solvent. Such an approach
would reduce the total energy requirement for preparing the ultimately-
desired fibrils~ in that the ethylene polymer would not be cooled and
. - .- : . . . : . :
.. . .. .
: , . . . ~ .
,
.
~5~
reheated. Moreover, the heat of p~lymeriZE~tl.On of th~ ethylene would
provide ~ substantlal portion of the energy required to prepare the hot
ethylene polymer solution. It h~s not been possible up t~ this time to
directly Frepare such hot solution~ of ethylene polymers of high mole-
cular weight by direc~ polyme~izatiDn of ethylene in a hydrocarbon
s~lvent. The difficulty that has been presented i~ the well-recognized
fact that the molecular weight of an ethylene polymer decreases as the
temperature employed ~n the polymerization is increased. With ~resently
known catalysts, it has not been po~sible to prepare ethylene polyme-rs
having an inherent viscosity of at least 3.5 in a hydrocarbon ~olvent by
carrying out the polymeri~ation at temperatures above 100C.
The present invention provides a yroces~ for preparing hot
hydrocarbon solutions of ethylene polymers having an inherent viscosity
of at least 3.5. The invention is based upon the observation that, when
ethylene is polymerized in a hydrocarbon solution in the presence o a
special type of polymeri~ation initiator, it is possible to prepare
ethylene polymers having an inherent viscosity of at least 3.5, even
when the polymerization is carried out at a temperature of at least
about 130C.
Thus according to the present invention there is
provided a process for preparing a hot hydrocarbon solution of
an ethylene polymer having an inherent viscosity of at least
3.5, which consists essentially of contacting ethylene wi~h a
polymerization initiator in a high boiling liquid hydrocarbon
at a tamperature of at least a~out 130C; said liquid hydro-
car~on having a boiling point range such that its vapor
pressure at 130C is not higher than 5 atmospheres; said poly-
merization initiator having been prepared by reacting an
aluminum alkyl selected from the group consisting of dialkyl
: aluminum hydrides, dialkyl aluminum halides, and trialkyl
aluminums with a supported, chemically-modified transition
-
-- 3 --
.
metal chloride product prepared by a process which consists
essentially of the sequential steps of:
~a) Suspending a finely-divided polymer in a 1-4 carbon atom
alkanol solution of a m~gnesium compound,
(b3 Vaporizing the alkanol from khe suspension of Step (a) to
deposit the magnesium compound, ~ogether w~th the quanti~y of
alkanol which forms a complex therewith, on ~he surface of
~he finely-divided polymer,
(c) Suspending the product of Step (b) in a liqtlid hydrocarbon 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) beinB selected from the group con-
sisting of organic thermoplastic polymers and thermoset polymers~
the particles of said pol~mer having at least one dim~nsion not
exceeding 600 microns, the magnesium compou~d eMployed in Step (a)
having the structure:
' MgX2' nH20
where X is Cl, F, Br, I9 N03, OC~3, OCOC~3, and n is not greater
tha~ 6; the magnesiu~ compound employed i~ Step (a) constituting
5-25 weight X of the combined welght of the finely-divided polymer
and the magn2sium compound; the alumlnum alkyl compound employed in
Step (c) being selec~ed from the group consisting of dialkyl
aluminum hydride~, dialkyl aluminum halides, and trialkyl alumlnums; : :
the quantity oE the alumlnum alkyl employ~d in Step (c) being not
in exce~s af the quantity tha~ will react wi~h the magnesium
compound-alkanol comple~ carried on the polymeric suppor~; the
transition metal chloride employed in Step (d) being selected from
~he group cons.!s~ing of titanium tetrachlorlde and vanadium oxy-
trichloride; and the quantity of the transition metal chlo~ide
compound employed i~ Step (d) bei~g at least molarly equivalent to
the quantity of the alum~num alkyl compound employed ln Step (c).
lC2 ~ 3a - :
.:- - : - . . . , ,,: : , . .
-' - : . : ' '
.. - .,
Hoe hydrocarbon solutions of an ethylene polymer havin~ an
inherent viscosity of at least 3.5 are prepared by contactlng ethylene
with a special type of polymerization initiator in a high-boiling liquid
hydrocarbon at a temperature of at least about 130C. The poly~eri
zation initiator employed in the procelss is the reaction product of (1)
an aluminum alkyl selected from the group consisting of dialkyl aluminum
hydride!s, dialkyl aluminum halides, and trialkyl aluminums and (2~ a
supported, chemically-modified transition metal chloride product pre-
pared by a multistep proces~s subsequently described.
- 3b -
- . -
The special polymerization initiators employed in the
process of the present invention are described in the copending
Canadian Patent application o~ Fa;indar K. Kochhar and Robert J.
%7~,3~
Rowatt, Serial No. ~ 3~, filed on May 3, 1977, and assigned
to the Assignee of this application-
The ~luminum alkyl employed in the preparation ~f the special
polymerization lnitiator may be either a dialkyl aluminum hydride, a
dialkyl aluminum halide, or a trialkyl aluminum. Typical exa~pl~s of
suitable alkyl aluminums include triethyl aluminu~, triisobutyl aluminum,
1~ diethyl aluminum hydride, and diethyl aluminum chloride. Such alkyl
aluminums should be of the purity and quality conventionally employed in
the preparation of Ziegler-type polymerization initiatorq.
The supported, chemically-modified transition metal chloride
product employed as the second component in the preparation of the
special polymerization initiators of the invention ls prepared by a
multistep process.
In the first step of the preparation of the ~upported,
chemically-modified, transition metal chloride compound, 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 therm~set polymer, or preferably an organic thermo-
plastic p~lymer. Thè polymeric support should be i~ a finely-divided
particulate form which has at least one dimension not e~ceeding about
600 microns and preferably having one dimension falling within the r~nge
of abou~ 1 t~ 200 microns. The polymeric ~upport may be of any desired
shape such as sp~res, rods, or c~linders. Suita~le polymeric
materials include poly (triallylisocyanurate), polye~hylene,
polypropylene, po:Ly (3-methylbutene), poly ~4-methylpentene),
polyamides, polyesber~, polyacrylamides, polyacrylonitriles, polycarkonates,
30 and cellulose. ~le essentially any po~ymer not
soluble in an alkanol can be employed
~ 4
,
~ . - - : - , . .
: .. ; .,-, . . . ..
~5~1~S . :~
for this purpose, it is preferred to employ an ethylene polymer, parti-
cularly an ethylene polymer having an inherent viscosity of at leasL
3.5.
The alkanol solution of a magnesium compound employed in the
treatment of the polymeric support in the first step of the preparation
will be an alkanol solution of a magnesium compound having the struc~
ture:
MgX2 . nH20
where X is an anion which imparts solubility of at least
1% in a lower alkanol (C4 or less), and n is not greater
than 6. Thus, X can represent Cl, F, Br, I, N03, OCOCH3,
or OCOH.
Magnesium compounds found to be par-ticularly suitable in the practice of
the invention include magnesium chloride, magnesium methoxide, magnesium
nitrate, and magnesium acetate. The alkanol in which the magnesium com-
pound will be dissolved will be an alcohol containing 1-4 carbon atoms
such as methanol, isopropanol, butanol and the like. The alkanol solu-
tion should contain a relatively high concentration of the magnesium com-
pound, e.g., desirably at least 5% by weight, by reason of the fact t~at
the alkanol subsequently will be removed from the process by vapori-
zation.
In carrying out the first step of the process, the polymeric
support wlll be suspended in a sufficient quantity of the alkanol solu-
tion 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
tXe magnesium compound to the extent required to thoroughly wet and
impregnate the polymeric carrier with the alkanol solution.
In the second step of~the process, the alkanol is vaporized
: .
from the suspension of the polymeric carrier in the alkanol solution so
as to deposit the magnesium~compound uniformly ovér the polymeric
,
~ - 5 -
carrier. The magLIesium compou~d is deposLted on the carrier in the
form of a complex with the alkanol. The precise structure of the com-
plex has not been established, but it i9 believed to contain l-~ mols
of alkanol per mol oE magnesium compound. It is observed, however, that
the magnesium compound-alkanol complex is in a highly active stake
particularly suitable for use in the preparation of the chemically-
modified, transition metal chloride compolmds 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 evapora-
tion is preferably carried out under reduced pressure. Care should be
exercised to remove the alkanol solution at moderate temperatures not
exceeding 150C and preferably not exceeding 75C. Frequently the dis-
tlllation 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. When a sweep gas is employed, it should be free of
water, oxygen and other compounds recognized as having a deleterious
effect upon Ziegler-type catalysts.
While a simple evaporation or distillation as described above
can be used to remove the alkanol, somewhat better results are obtained
if at least the final portions of the alkanol are removed by codistilla-
t~on 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 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
,
-- 6 --
,
.
of the uncomplexed alkanol are removed from the system, the vapor tem-
perature oE the distillate will rise to the boiling point o~ the hydro-
carbon at the prevailing pressure employed in the distillation. Thus,
the observed boiling point of the distlllate 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 prepara-
tion of Ziegler-type catalysts. Predominantly aliphatic hydrocarbons
such as heptanes and octanes are preferred. The hydrocarbon employed
should be purified in a manner so as to remove therefrom molsture and
other materials kno~l to have a deleterious 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
hydrocarbon of the type previously described. Normally, such a slurry
already will have been prepared, particularly where the Einal traces of
the alkanol are removed by codistillation as described above. A suit
able aluminum alky compound such as diethyl aluminum chloride then will
be added to the slurry. The aluminum alkyl reacts with the ~agnesium
compound-alkanol complex carried on the polymeric support. The mechanism
by which the two components reac~t and the structure of the resulting
reaction product have not been fully established. The evidence tha, a
chemical reaction takes place is that a gas, possibly an alkane, is
Eormed 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 polymeric support.
The aluminum alkyl employed in the step of the process de-
-:
; scribed immediately above may be a dialkyl halide, a dialkyl aluminum
hydride, or a trialkyl aluminum, with the dialkyl aluminum~halides being
preferred. Typical examples of~ suitable alkyl aluminums include tri-
ethyl aluminum, triisobutyl~aluminum, diethyl aluminum hydride and
diethyl aluminum chloride.
~ .
: :
-- 7 --
~ t~ 5
The alum:Lnum alkyl should be employed -In a quantity such 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 complet:Lon of thls step of the
process, contains little or no unreacted aluminum alkyl in the hydro-
carbon 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. The
presence of such conventional ~legler-type catalyst will tend to mlnl-
mize the advantages obtalned wlth the present invention.
The precise quantity of the aluminum alkyl to be employed will
be somewhat dependent upon the completeness with whlch uncomplexed
alkanol is removed from earlier steps of the process. This results from
the fact that any free, uncomplexed alkanol present in the reactlon system
will react wlth the aluminum alkyl compound. Ordinarlly, the applicant
prefers to employ approxlmately 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 necessaryl
20 the presence of unreacted aluminum alkyl can be determined either quali-
tatively or quantitively 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. Ana
lytical methods for measuring the concentration of aluminum alkyls in
hydrocarbons are known in the art.
The use of less 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
reaction product which will be converted into a slightly different
polymerlzation catalyst in subsequent processing steps.
- 8 -
-
, . , - .. . . , , :
.. ~ . . , - ,, ., . -. . .
' : , . . . , : , ...
5~
In the next step of the proeess, a trans1tion metal ehloride
of the group consis~ing of tltanium tetrachloride and vanadiuTn oxytri--
chloride is added to tile reaction mixt~lre of the previous step, ~7hich
contains as the active reactant ~he reaction product formed between the
supported magnesi~lm compound-alkanol complex and the aluminum alkyl.
The transition metal chloride reacts with the previously prepared reaction
product and is reduced to a lower valence state. This supported,
chemically-modified, transition metal chloride compound is the ulti-
mately desired catalyst component and is insoluble 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 of 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 for 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 completion in the shortest possible period of
time.
As the supported, chemically-modified, transition metal chloride
product is insoluble in the hydrocarbon medium, it can be recovered by
filtration 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 production 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 the
~ product in the slurry in which it is prepared. In such situations, it
'~ ,: . . . :, ' .
is desirable to re~ove any unreacted transition metal clllo~ide from
the system. Such removal can be effected by si~ply distilling the
h~drocarbon from the slurry at either atmospheric or reduced pressure.
The unreacted transition metal chloride codistills with the hydrocarbon.
The distillation is continued until the distillate gives a negative
test for chloride.
To p~epare the special polymerization initiator used for the
polymerlzation of ethylene; the supported, chemically-modified transl-
tion me~al chloride product ls reacted with an aluminum alkyl compound
in a hydrocarbon medium, preferably the same hydrocarbon that will be
used in the subsequent polymeriæation. The reaction is carried out in amanner generally equivalent to that employed to prepare more conven-
tional Ziegler-type catalystsO The supported, chemically-modified
transition metal chloride product is employed in the same molar propor-
tions as conventional transition metal chlorides are employed in their
reactions with aluminum alkyls. Typically, the two components are
employed in proportions to provide an Al/Ti atomic ratio of about
0.5 ~ 1, or preferably 1.0 - 5.0:1. While dialkyl aluminum hydrides
and dialkyl aluminum halides csn be employed for this purpose~ the
trialkyl aluminums and particularly triethyl aluminum and triisobutyl
aluminum are the preferred aluminum alkyls to be employed in the prepara-
tion of such polymerization initiators.
The special polymerization initiators prepared as described --
~ above have a nu~ber of features which make them particularly effective
`~ and desirable for use in the polymerization bf ethylene by the method of
the present invention. Initially, it will be noted that the magnesiu~
, ~ compo~md, the transition metal compound, and the aluminum alkyl compounds
are employed in the precise quantities* required in the final polymeri-
zation initlator. Thus~ no expenslve compounds are employed in excess
*The transition metal chloride may be employed in slight excess of that
stoichiometrically required for reasons previously discussed.
:~ :
.
-- 10 -- ~
. ~
s~
of their actual need. The polymerization initiators have high pro-
ductivity rates and provide low production costs for the ethylene polym~rs
produced. In addition, by reason of the high catalyst productivities,
the finished polymers contain very low co~centrations of metallic catalyst
residues so that, for most purposes, they need not be removed from the
polymers. Yet another advantage of the polymerization initiators is
that they have a specific gravity substantially the same as the hydro-
carbon solvent employed in the ethylene polymerization process. Thus, a
uniform dispersion of the polymerization catalyst in the polymerizatlon
solvent is more easily obtained than is the case with more conventional
Ziegler-type catalysts.
The polymerization of ethylene is carried out by suspending
the special polymerization initiator in an appropriate hi~h-boiling
liquid hydrocarbon, heating the hydrocarbon to the desired reaction
temperature, and feeding polymerization-grade ethylene to the reaction
zone. If the polymerization is carried out batchwise, the polymerization
is continued until the concentration of the ethylene polymer reaches the
desired level. Ordinarily, the polymerization is carried to the point
at which the ethylene polymer reaches a concentration of at least 3
weight %, and preferably 4-7 weight %. Ordinarily, the polymerization
cannot be carried beyond the point at which the ethylene polymer con-
stitutes more than about 7 weight % of the reaction mixture. This pro-~ -
cess limitation is~set by the practical consideration that higher solids
solutions are too viscous for easy handling; the high viscosity resulting
; from the very high molecular weight of the ethylene polymer~produced in
~the process. It is preferred to carry out the polymerization by a con-
tinuous process with ethylene, the~special polymerization initiator, and
.
the hydrocarbon being continuously fed to the reaction zone wi-th a
polymer solution being continuously withdrawn from the reaction zone.
The feed rate and the~withdrawal rate are selected 90 that the residence
time of ethylene in the reaction zone is such~that the polymer solution
being withdrawn from the reactor has an ethylene polymer content within
the desired range previously noted.
The hydrocarbon employed in the process should have a boiling
point range such that its v~por press~lre at 130C is not higher than 5
atmospheres and preEerably less than 2 atmospheres. It is preferred to
employ a predominantly aliphatic hydrocarbon mixture such as kerosene,
but the hydrocarbon employed may contain modest percentages of aromatic
and cycloaliphatic hydrocarbons without adversely affecting the process.
The hydrocarbon employed should be carefully dried, as it is well-known
that water acts to poison or deactivate Ziegler-type polymeri-
zation initiators. Depending upon the source oE the hydrocar~on,
additional treatments may be required to remove organic compounds
containing nitrogen, oxygen, or sulEur atoms, as it is known that such
compounds also tend to deactivate Ziegler-type polymerization initiators.
The polymerization initiator should be employed in the
process at a concentration within the range of 0.01 to 4 grams per
liter of reactor volume. The polymerization will be carried out at a
temperature of at least about 130C, and no advantages are obtained by
carrying out the polymerization at a temperature above about 150C.
`~ The polymerization normally will be carried out at a superatmospheric
pressure of at least about 2 and preferably at least about 30 atmospheres
2~ to maintain a sufficient concentration of ethylene in the reaction
medium to provide reasonable rates of poly~erization.
The polymeri~ation temperature, the concentration of polymeri-
zation initiator, and concentration of ethylene (controlled by the
ethylene partial pressure) are maintained in appropriate ~alance to
produce an ethylene polymer having inherent viscosity of at least 3.5.
Methods for determining the inherent viscosities of ethylene polymers
are set forth in the art, e.g., see British Patent 1,372,116. The most
unexpected and unique characteristic of the process of the invention i5
that ethylene polymers of such high inherent viscosity can be produced
at the high temperatures employed in this process. It is well recognized
in the art that increasing the polymeri~ation temperature in a process
'
- 12 - H-6
,
.
ordinarily reduces the molecular weight and tlle inherent-visco~ity oE
the ethylene polymers produced. Moreover, most Ziegler-type catalysts
are deactivated at the temperature employed in the process o~ the
present invention.
The process of the invention provides very high yields of
polymer based on the polymeriza-tion initiator employed. Typically the
process provides minimum yields of the order of about 1200 grams of
polymer per gram oE titanium per hour. As a result of the high yield,
the polymers produced contain a sufficiently low level of catalyst resi-
dues that no post polymerization treatment is required to remove such
residues.
While the process of the invention is designed principally to
produce homopolymers of ethylene, it is also possible to produce
copolymers of ethylene with C3 and higher monoolefins, such as propylene
and butylene. It is preferred, however, to limit the concentration of
any higher olefin comonomer in the monomer mixture to a level not more
than about 25 mol % of the ethylene employed in the process. Minor
concentrations of hydrogen can be employed in the process to modify the
molecular weight of the ethylene polymers produced in the process.
The following examples are set forth to illustrate more
clearly the principle and practice of this invention to those skilled in
the art.
Examples 1-3 -
Three polymerization initiators were prepared for use in the
polymerization of ethylene by the process of this invention.
Part A
Preparation of Support
A ~-liter reaction vessel fitted with a stirrer, a reflux
condenser, a dropping funnel9 and heating and cooling means; was charged
with a methanolic solution of magnesium chloride prepared by dissolving
75 grams of magnesium chloride in l liter of methanol. Six hundred
- 13 -
~ ~5~ 5
seventy grams o~ a Einely-divided powder of high density yolyethylene
having an average part-icle diameter o~ less tharL 40 microns was slurried
in the methanolic solu~ion of 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 pres-
sure then was reduced to about 10 mm of ~lg to remove methanol f~oM the
system. Heating was continued for two hou-rs under these conditions to
assure removal of all methanol which did not form a complex with the
magnesium chloride deposited on the polyethylene support. The powder
was removed from the reaction vessel and ground to pass through a 40-mesh
U.S. screen.
Part B
Preparation of Chemically-Modified
Transition Metal Chloride Compound
The magnesium chloride treated polyethylene powder prepared as
described above in the amount of 200 grams, an appropriate quantity of
heptane, and an appropriate quantity of diethyl aluminum chloride, was
charged to a 4-liter reactor equipped as described above. This reaction
mixture was stirred for one hour while maintaining the temperature at
25C. Evolution of a gas was noted. At this point in the reaction, it
is believed that the charged diethyl aluminum chloride has been chemi-
cally bonded to the polymeric support or one of the chemicals carried
thereon. The reaction mixture then was heated to 80C and an appropriate
quantity of TiC14 was added to the reaction mixture from the dropping
funnel over a period of one hour. The reaction mixture then was stirred
for an additional 16-20 hours, while maintainin~ the temperature at 80C
to assure complete reaction between the TiC14 and the components carried
on the support. Prior to the addition of the TiC14, the solids present
in the slurry were light yellow in color, but the color changed to a
purple-red shortly after the addition of the TiC14. The liquid present
in the slurry was removed by decantation, and the solids were washed
with several aliquots of heptane until the heptane gave no test for the
presence of chlorides. The solids then were recovered and dried under
vacuum at ambient temperature.
- 14 -
~ t~ 5
Part C
_ation of Polymeri~at:ion Initiator
_ __ _.___
Two parts of a product prepared in Part B were s~lspended in
500 parts of heptane. Thirty-six parts of triethyl aluminum (added as
a 25% solution heptane) then were added over a period of 10 minutes
with stirring. This dispersion of polymer:i~ation initiator wa~ stored
under rigorously anhydrous conditions for use in the polymerization
of ethylene.
In all of the procedures described above, care was exercised
to carry out all reactions under rigorously anhydrous conditions. All
reactants employed were purified grades and contained no identifiable
concentrations of water or reactive hydrogen compounds known to have a
deleterious effect upon ~iegler-type polymerization reactions.
In Table I, Section A shows the proportions of reactants
employed in the reactions of Part B above. Section B of Table I sets
forth the chemical analysis of each chemically-modified transition metal
chloride compound prepared in Part B above.
TABLE I
Section A
Preparation of Thermically-Modified
Transition Metal Chloride Compound
Example Catalyst Heptane DEAC (l) TiC14
No. Support~ gms ml gms gms
- - _
1 200~ 400 72 ~63
2 200300 36 345 ~
3 200300 36 345
Section B
_Catalyst Analysis
- Total
Example Magnesium Aluminum Chlorine Titanium Inorganic
30 No ~ wt % wt % wt % wt % wt %
.__
1 1.7 0.3 9.7 2.0 13.7
2 2.0 4.1 15.9 2.6 24.6
3 1.7 2.7 15.1 2.8 22.3
:
:` -' 15 -
,
Example 4
_
Sixty-seven grams of part-Lculate high density polyethylene,
having a particle size less than 40 microns, was suspended in 100 ml of
methanol containing 7.5 grams of dissolved magnesium chloride in a 1-
liter reaction vessel equipped as described in Example 1. Two hundred
fifty ml of heptane then was added to the reactor and the reaction
mixture was heated to take off an overhead fraction having a boiling
point of 59-60C. After about 175 ml of distillate was recovered, the
temperature of the distillate rose to the atmospheric boiling point of
heptane.
The reactor was cooled to room temperature and 70 ml of a hep-
tane 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 during this addition. Thereafter, the
reaction mixture was heated to 80C and 138 grams of TiCl~ was added
dropwise to the reaction system. At the start of tha addition of the
TiC14 the reaction mixture was a straw yellow in color, but about 15
minutes after the addition of the TiC14 had been completed, the solids
in the reaction system changed to a purple-red color. Heating was con-
tinued with stirring for another 16 hours. Thereaf-ter the reactor was
cooled and the catalyst solids were recovered by filtration. The re-
covered solids were washed with aliquots of dry heptane un-til the wash
heptane gave a negative test for soluble chlorides.
A total of 0.2 gram of catalyst component described in the
paragraph above was suspended in 50 ml of heptane having dissolved
therein 0.36 gram of triethyl aluminum.
~ .
- 16 -
'
t 5j~7~
EXAMPLE 5
A five-gallon sti~red rPactor was charged with 12.3 kg. of
kerosene (Gulfsol 20) and a slurry of 2 grams of the catalyst of E~ample
2 in 40 ml of heptane. The reactor was heated to a temperature of 145C
over a period of about one hour with a bleed in the reactor being opened
periodically to vent the minor amount of heptane charged to the reactor.
Polymerization grade ethylene then was fed to the reactor until the
reactor pressure increased to 200 psig. Controls then were set to feed
the ethylene to the reactor at a rate of 0.3 pound per hour. Ethylene
10 gas was fed to the reactor over a period of 3.5 hours. After the feed
of ethylene was cut off 7 stirring was continued for an additional hour
at 145C to convert the remainin~ ethylene to polymer. The final reaction
product consisted o a hydrocarbon solution containing 3 wei~ht % of
ethylene polymer.
The polymer solution was cooled to room temperature to precipi--
tate the ethylene polymer therefrom. The recovered polymer solids were
washed with several aliquots of heptane and dried overnight in a vacuum
oven at a temperature of about 50C. The inherent v~scosity of the
recovered polymer, measured by the method as set forth in British
20 patent l,372,116, was greater -than 3.5. The polymer's high load melt
index, determined by AS~M 1238-70 (Condition F), was less than 0.02.
EXAMPLE 6
Example 6 was repeated and the hot polymer solution was employed
directly to prepare fibrils by the method of British patent 1,372,116.
The recovered fibrils were of better quality than a control lot of
fibrils prepared from a 3% solution of ethylene polymer having a substan-
tially identical inherent viscosity which was dissolved in the same
kerosene employed in Example 5.
As the two poIymers employed had substantially identical
inherent viscosities and were employed in the same concentration in the
sa~e kerosene solvent, it is believed that the improved quality oE the
/`ac~ R~k
- 17 -
- , . . ; ~ - , .
fibrils resulted by reason of the fact that, in the preparation of the
control hydrocarbon solution, m:inor quantities of the ethylene polymer
were not completely dissolved and gave rise to imperfections in the
final fibrils.
EXAMPLES 7 - 1
Three additional solutions of h:igh molecular weight ethylene
polymer were prepared by the method descr:ibed in E~ample 5, except
that the polymeri7ation initiator employed was, respectively, the poly-
merization initiator prepared ln Examples 1, 3, and 4. In each in~tance,
the polymerization ran smoothly and provided an ethylene polymer having
an inherent viscosity in excess oE 3.5, as determined by the method setforth in British patent 1,372,116.
' ,~
- 18 ~
