A supported alpha-olefin polymerization catalyst composition is synthesized by reacting (1) a slurry of a solid catalyst carrier in a non-polar solvent, e.g., hexane, with a dialkyl organomagnesium composition; (2) contacting the slurry of step (1) with a chlorinated alcohol; (3) contacting the slurry of step (2) with at least one transition metal compound; (4) removing the non-polar solvent to obtain a dry-flowing powder; and, (5) activating the powder with an activator. The resulting catalyst composition has high polymerization activity in the polymerization of C.sub.2 -C.sub.10 alpha-olefins and exhibits very good higher (C.sub.3 -C.sub.10) alpha-olefin incorporation properties in the copolymerization of ethylene with the higher alpha-olefins.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a method for polymerizing alpha-olefins, a 
catalyst for such a polymerization method and a method for producing such 
a catalyst. In particular, the present invention relates to a highly 
active catalyst, and a method for preparation thereof, which has excellent 
higher alpha-olefin incorporation properties and produces copolymers of 
ethylene with such higher alpha-olefins of excellent properties. The 
invention is also directed to a highly productive polymerization process 
carried out with the catalyst of the invention. 
2. Description of the Prior Art 
Linear low density polyethylene polymers possess properties which 
distinguish them from other polyethylene polymers, such as homopolymers of 
polyethylene. Certain of these properties are described in Anderson et al, 
U.S. Pat. No. 4,076,698. 
Karol et al, U.S. Pat. No. 4,302,566, describe a process for producing 
linear low density polyethylene polymers in a gas phase, fluid bed 
reactor. 
Graff, U.S. Pat. No. 4,173,547, Stevens et al, U.S. Pat. No. 3,787,384, 
Strobel et al, U.S. Pat. No. 4,148,754, and Ziegler, deceased, et al, U.S. 
Pat. No. 4,063,009, each describe various polymerization processes 
suitable for producing forms of polyethylene other than linear low density 
polyethylene, per se. 
Graff, U.S. Pat. No. 4,173,547, describes a supported catalyst obtained by 
treating a support with both an organoaluminum compound and an 
organomagnesium compound followed by contacting this treated support with 
a tetravalent titanium compound. 
Stevens et al, U.S. Pat. No. 3,787,384, and Strobel et al, U.S. Pat. No. 
4,148,754, describe catalysts prepared by first reacting a support (e.g., 
silica containing reactive hydroxyl groups) with an organomagnesium 
compound (e.g., a Grignard reagent) and then combining this reacted 
support with a tetravalent titanium compound. According to the teachings 
of both of these patents, no unreacted organomagnesium compound is present 
when the reacted support is contacted with the tetravalent titanium 
compound. 
Ziegler, deceased, et al, U.S. Pat. No. 4,063,009, describe a catalyst 
which is the reaction product of an organomagnesium compound (e.g., an 
alkylmagnesium halide) with a tetravalent titanium compound. The reaction 
of the organomagnesium compound with the tetravalent titanium compound 
takes place in the absence of a support material. 
A vanadium-containing catalyst, used in conjunction with 
triisobutylaluminum as a co-catalyst, is disclosed by W. L. Carrick et al 
in Journal of American Chemical Society, Volume 82, page 1502 (1960) and 
Volume 83, page 2654 (1961). 
Nowlin et al, U.S. Pat. No. 4,481,301, disclose a supported alpha-olefin 
polymerization catalyst composition prepared by reacting a support 
containing OH groups with a stoichiometric excess of an organomagnesium 
composition, with respect to the OH groups content, and then reacting the 
product with a tetravalent titanium compound. 
Dombro, U.S. Pat. Nos. 4,378,304 and 4,458,058, disclose an olefin 
polymerization catalyst composition synthesized by sequentially reacting: 
(1) a porous support with a Group IIA organometallic compound, e.g., a 
dialkylmagnesium; (2) the product of (1) with water or a hydrocarbyl 
alcohol, e.g., methanol; (3) the product of (2) with a transition metal 
compound or compounds. The product of the synthesis reaction is activated 
with a co-catalyst which is a Group IA, IIA, IIIA and/or IIB 
organometallic compound, including hydrogen. Suitable co-catalysts are 
n-butylithium, diethylmagnesium, triisobutylaluminum and diethylaluminum 
chloride. 
Best, U.S. Pat. Nos. 4,558,024, 4,558,025 and 4,579,835, disclose olefin 
polymerization catalyst compositions prepared by reacting together a 
porous particulate material, an organic magnesium compound, an 
oxygen-containing compound, a transition metal compound, e.g., a titanium 
compound (the '024 patent) or a vanadium compound (the '835 patent), and a 
co-catalyst. Some of the catalyst compositons of Best also include an acyl 
halide (e.g., see the '835 and the '025 patents). 
When the LLDPE resins are fabricated into injection-molded products, it is 
imperative to assure that such products are not susceptible to warping or 
shrinking. As is known to those skilled in the art, the degree of warping 
or shrinking can be predicted from the molecular weight distribution of 
the resins. Resins having relatively narrow molecular weight distribution 
produce injection-molded products exhibiting a minimum amount of warping 
or shrinkage. Conversely, resins having relatively broad molecular weight 
distribution produce injection-molded products more likely to undergo 
warping or shrinkage. One of the measures of the molecular weight 
distribution of the resin is melt flow ratio (MFR), the ratio of high melt 
flow index (HLMI or I.sub.21) to melt index (I.sub.2) for a given resin. 
The melt flow ratio is believed to be an indication of the molecular 
weight distribution of the polymer: the higher the MFR value, the broader 
the molecular weight distribution. Resins having relatively low MFR 
values, e.g., of about 20 to 50, have relatively narrow molecular weight 
distribution. Additionally, LLDPE resins having such relatively low MFR 
values produce films of better strength properties than resins with high 
MFR values. Many catalyst systems exhibit a tendency to produce resins 
whose MFR values, although initially low, increase with increased 
concentration of the catalyst activator, also known as a co-catalyst, such 
as various aluminum alkyls. However, under certain circumstances, it is 
desirable to increase the catalyst activator concentration without 
substantially affecting the resin MFR, e.g., to improve catalyst 
productivity and/or comonomer incorporation. 
Another important property of LLDPE resins, manufactured into products 
coming into contact with articles subject to FDA regulations, e.g., 
foodstuffs, is hexane extractables which is a measure of the amount of low 
molecular weight and/or highly branched polymer fractions capable of being 
extracted from the manufactured products, e.g., plastic food containers, 
by hexane extraction. The FDA imposed strict regulations on the amounts of 
allowable hexane extractables in such plastic products. 
Thus, Allen et al, U.S. Pat. No. 4,732,882, disclose an alpha-olefin 
polymerization catalyst composition activated with trimethylaluminum which 
produces polymers having relatively low values of MFR and low hexane 
extractables. However, the productivity of the polymerization process 
carried out with such a catalyst composition is lower than that of the 
process carried out with the same catalyst compositions activated with 
more commonly-used activators, such as triethylaluminum or 
triisobutylaluminum. 
Accordingly, it is important to provide a catalyst composition capable of 
producing alpha-olefin polymers having relatively narrow molecular weight 
distribution (low MFR values) which remains substantially constant with 
varying amounts of the co-catalyst, and which catalyst composition has 
high activity. 
It is therefore a primary object of the present invention to provide a high 
activity catalyst for the polymerization of alpha-olefins yielding 
products of a relatively narrow molecular weight distribution which is 
maintained substantially constant with varying amounts of the co-catalyst 
concentration. 
It is another object of the present invention to provide a high activity 
catalyst composition which produces alpha-olefin polymers having 
relatively low hexane extractables. 
It is yet an additional object of the present invention to provide a 
catalyst composition having excellent higher alpha-olefin incorporation 
properties. 
It is an additional object of the present invention to provide a catalytic 
process for polymerizing alpha-olefins which yields linear low density 
polyethylene of a relatively narrow molecular weight distribution at high 
productivity rates. 
SUMMARY OF THE INVENTION 
A supported alpha-olefin polymerization catalyst composition of this 
invention is prepared in a multi-step process. In the first step, a 
mixture of a solid, porous carrier and a non-polar solvent is contacted 
with at least one organomagnesium composition of the formula 
EQU R.sub.m MgR.sub.n ' (I) 
where R and R' are the same or different C.sub.4 -C.sub.12 alkyl groups, m 
and n are each 0, 1 or 2, providing that m+n equals the valence of Mg. 
Subsequently, the mixture of the first step is contacted with at least one 
chlorinated alcohol of formula (II), R.sub.2 --OH, where R.sub.2 is a 
C.sub.2 -C.sub.10 chlorinated alkyl. The resulting mixture is then 
contacted with at least one transition metal compound soluble in the 
non-polar solvent. The product (also referred to herein as "catalyst 
precursor") is dried and it is activated with a catalyst activator. The 
resulting activated catalyst composition has very high productivity in the 
polymerization of alpha-olefins, very effective higher comonomer (i.e., 
C.sub.3 -C.sub.10 alpha-olefin) incorporation properties in the 
copolymerization of ethylene with such higher comonomers and it produces 
polymers having relatively narrow molecular weight distribution and low 
hexane extractables.

DETAILED DESCRIPTION OF THE INVENTION 
The polymers prepared in the presence of the catalyst composition of this 
invention are linear polyethylenes which are homopolymers of ethylene or 
copolymers of ethylene and higher alpha-olefins. The polymers exhibit 
relatively low values of melt flow ratio (MFR), as compared to similar 
polymers prepared in the presence of previously-known catalyst 
compositions, e.g., those disclosed by Nowlin et al, U.S. Pat. No. 
4,481,301. Thus, the polymers prepared with the catalyst composition of 
this invention are especially suitable for the production of films and for 
injection molding applications. 
Catalysts produced according to the present invention are described below 
in terms of the manner in which they are made. 
Catalyst Synthesis 
The carrier material is usually an inorganic, solid, particulate porous 
material which is inert to the other components of the catalyst 
composition and to the other active components of the reaction system. The 
carrier material can be made from such inorganic materials as oxides of 
silicon and/or aluminum. The carrier material is used in the form of a dry 
powder having an average particle size of from about 1 micron to about 250 
microns, preferably from about 10 microns to about 150 microns. The 
internal porosity of the carrier should be higher than 0.2 cm.sup.3 /gm, 
e.g., from about 0.5 cm.sup.3 /gm to about 15 cm.sup.3 /gm. The specific 
surface area of the carrier is at least about 3 square meters per gram 
(m.sup.2 /gm), and preferably at least about 50 m.sup.2 /gm. The carrier 
material should be dry, that is, free of absorbed water. Drying of the 
carrier material can be effected by heating at about 100.degree. to about 
1000.degree. C. and preferably at about 600.degree. C. When the carrier is 
silica, it is heated at a temperature of at least about 200.degree. C. The 
carrier material must have at least some active hydroxyl (OH) groups to 
produce the catalyst composition of this invention. 
In the most preferred embodiment, the carrier is silica which, prior to the 
use thereof in the first catalyst synthesis step, is dehydrated by 
fluidizing with dry nitrogen and heating at about 600.degree. C. for about 
16 hours to achieve a surface hydroxyl group concentration of about 0.7 
mmols/gm. The silica of the most preferred embodiment is a high surface 
area, amorphous silica (surface area=300 m.sup.2 /gm; pore volume of 1.65 
cm.sup.3 /gm), and it is a material marketed under the trandenames of 
Davison 952 or Davison 955 by the Davison Chemical Division of W. R. Grace 
and Company. It has the morphology of spherical particles, e.g., as 
obtained by a spray-drying process. 
The carrier material is slurried in a non-polar solvent and the resulting 
slurry is contacted with at least one organomagnesium composition having 
the empirical formula (I). The slurry of the carrier material in the 
solvent is prepared by introducing the carrier material into the solvent, 
preferably while stirring, and heating the mixture to about 25.degree. to 
about 100.degree. C., preferably about 40.degree. to about 60.degree. C. 
The slurry is then contacted with the aforementioned organomagnesium 
composition, while the heating is continued at the aforementioned 
temperature. 
The organomagnesium composition has the empirical formula R.sub.m MgR.sub.n 
', where R and R' are the same or different C.sub.4 -C.sub.12 alkyl 
groups, preferably C.sub.4 -C.sub.10 alkyl groups, more preferably C.sub.4 
-C.sub.8 unsubstituted alkyl groups, and most preferably both R and R' are 
n-butyl groups, and m and n are each 0, 1 or 2, providing that m+n is 
equal to the valence of Mg. 
Suitable non-polar solvents are materials in which all of the reactants 
used herein, i.e., the organomagnesium composition, the compound of 
formula (II) and the transition metal compounds are at least partially 
soluble and which are liquid at reaction temperatures. Preferred non-polar 
solvents are alkanes, such as hexane, n-heptane, octane, nonane, and 
decane, although a variety of other materials including cycloalkanes, such 
as cyclohexane, aromatics, such as benzene and ethylbenzene, can be 
employed. The most preferred non-polar solvent is hexane. Prior to use, 
the non-polar solvent should be purified, such as by percolation through 
silica gel and/or molecular sieves, to remove traces of water, oxygen, 
polar compounds, and other materials capable of adversely affecting 
catalyst activity. 
In the most preferred embodiment of the synthesis of this catalyst it is 
important to add only such an amount of the organomagnesium composition 
that will be deposited--physically or chemically--onto the support since 
any excess of the organomagnesium composition in the solution may react 
with other synthesis chemicals, and precipitate outside of the support. 
The carrier drying temperature affects the number of sites on the carrier 
available for the organomagnesium composition--the higher the drying 
temperature the lower the number of sites. Thus, the exact molar ratio of 
the organomagnesium composition to the hydroxyl groups will vary and must 
be determined on a case-by-case basis to assure that only so much of the 
organomagnesium composition is added to the solution as will be deposited 
onto the support without leaving any excess of the organomagnesium 
composition in the solution. Furthermore, the molar amount of the 
organomagnesium composition deposited onto the support is greater than the 
molar content of the hydroxyl groups on the support. Thus, the molar 
ratios given below are intended to serve only as an approximate guideline 
and the exact amount of the organomagnesium composition in this embodiment 
must be controlled by the functional limitation discussed above, i.e., it 
must not be greater than that which can be deposited onto the support. If 
greater than that amount is added to the solvent, the excess may react 
with the compound of the formula (II), thereby forming a precipitate 
outside of the support which is detrimental in the synthesis and use of 
the catalyst and must be avoided. The amount of the organomagnesium 
composition which is not greater than that deposited onto the support can 
be determined in any conventional manner, e.g., by adding the 
organomagnesium composition to the slurry of the carrier in the solvent, 
while stirring the slurry, until the organomagnesium composition is 
detected as a solution in the solvent. 
For example, for the silica carrier heated at about 200.degree. C. to about 
850.degree. C., the amount of the organomagnesium composition, such as 
dibutylmagnesium (DBM), added to the slurry is such that the molar ratio 
of Mg to the hydroxyl groups (OH) on the solid carrier is about 1:1 to 
about 3:1, preferably about 1.25:1 to about 3:1. In one particularly 
preferred embodiment silica is heated at about 600.degree. C., and the 
amount of the organomagnesium composition is such that the molar ratio of 
Mg to OH on the silica is about 2.3:1 to about 2.6:1. The organomagnesium 
composition dissolves in the non-polar solvent to form a solution. 
It is also possible to add such an amount of the organomagnesium 
composition which is in excess of that which will be deposited onto the 
support and then remove, e.g., by filtration and washing, any excess of 
the organomagnesium composition. However, this alternative is less 
desirable than the most preferred embodiment described above. 
After the addition of the organomagnesium composition to the slurry is 
completed, the slurry is contacted with at least one chlorinated alcohol 
of the formula (II) 
EQU R"--OH (II) 
where R" is a chlorinated C.sub.2 -C.sub.10 alkyl group, preferably R" is a 
chlorinated C.sub.2 -C.sub.4 normal alkyl group and more preferably R" is 
a chlorinated ethyl group. In one especially preferred embodiment, the 
compound of formula (II) is 2,2,2-trichloroethanol. The term "chlorinated 
alcohol" as used herein designates a C.sub.2 -C.sub.10 alcohol having at 
least one of its hydrogens on the second (beta) or higher carbon atom 
replaced by chlorine. Thus, alcohols having chlorine on the first (alpha) 
carbon atom of the alcohol are not suitable for use in this invention. 
Carbon atoms of the alcohol are named in a conventional manner by naming 
the carbon most distant from the hydroxyl group (OH) as the alpha carbon, 
with the next carbon being beta carbon, etc. Examples of suitable 
chlorinated alcohols are 2-chloroethanol, 2,2-dichloroethanol, 
2,2,2-trichloroethanol, 2-chloro-propanol, 2,2-dichloro-propanol, 
2,2,3-trichloro-propanol, 2,2,3,3-tetrachloro-propanol, 
2-chloro-n-butanol, 2,3-dichloro-n-butanol, 2,3,4-trichloro-n-butanol, 
2,3,4,4-tetrachloro-n-butanol, and 2,2,3,3,4,4-hexachloro-n-butanol. We 
found that the use of the chlorinated alcohol in the synthesis of our 
catalyst composition substantially improves the activity and higher 
alpha-olefin (e.g., 1-butene, 1-pentene, 1-hexene or 1-octene) 
incorporation properties of the catalyst as compared to the use of 
analagous non-chlorinated alcohols or to the catalyst synthesized without 
any alcohols. The amount of the compound of the formula (II) used in this 
synthesis step is sufficient to convert substantially all of the magnesium 
alkyl (MgR or MgR') groups on the carrier to magnesium alkoxy (MgOR") or 
magnesium chloride (Mg-Cl) groups. In a preferred embodiment, the amount 
of the formula (II) compound added is such that substantially no excess 
thereof is present in the non-polar solvent after substantially all of the 
magnesium alkyl groups are converted to the magnesium alkoxy or 
magnesium-chloride groups on the carrier to prevent the reaction of the 
formula (II) compound with the transition metal compound outside of the 
carrier. For example, for the silica heated at about 200.degree. to about 
850.degree. C., the amount of the chlorinated alcohol of the formula (II) 
used herein is about 0.40 to about 3.0 mmols of chlorinated alcohol per 
gram of dried silica. This synthesis step is conducted at about 25.degree. 
to about 65.degree. C., preferably at about 30.degree. to about 55.degree. 
C., and most preferably at about 30.degree. to about 40.degree. C. 
After the addition of the formula (II) compound is completed, the slurry is 
contacted with at least one transition metal compound soluble in the 
non-polar solvent. This synthesis step is conducted at about 25.degree. to 
about 65.degree. C., preferably at about 30.degree. to about 55.degree. 
C., and most preferably at about 30.degree. to about 40.degree. C. In a 
preferred embodiment, the amount of the transition metal compound added is 
not greater than that which can be deposited onto the carrier. The exact 
molar ratio of Mg to the transition metal and of the transition metal to 
the hydroxyl groups of the carrier will therefore vary (depending, e.g., 
on the carrier drying temperature) and must be determined on a 
case-by-case basis. For example, for the silica carrier heated at about 
200.degree. to about 850.degree. C., the amount of the transition metal 
compound is such that the molar ratio of the transition metal, e.g., Ti, 
derived from the transition metal compound, e.g., TiCl.sub.3 or 
TiCl.sub.4, to the hydroxyl groups of the carrier is about 1 to about 3.0, 
preferably about 1.5 to about 2.5, and the molar ratio of Mg to the 
transition metal, e.g., Ti, is about 1 to about 4, preferably about 1.5 to 
about 3.5 and more preferably about 1.65 to about 3.00. We found that 
these molar ratios produce a catalyst composition which produces resins 
having relatively low melt flow ratio (MFR) values of about 20 to about 
35. As is known to those skilled in the art, such resins can be utilized 
to produce high strength films and injection molding products which are 
resistant to warping or shrinkage. 
Suitable transition metal compounds used herein are compounds of metals of 
Groups IVA, VA, VIA or VIII of the Periodic Chart of the Elements, as 
published by the Fisher Scientific Company, Catalog No. 5-702-10, 1978, 
providing that such compounds are soluble in the non-polar solvents. 
Non-limiting examples of such compounds are titanium and vanadium halides, 
e.g., titanium tetrachloride, TiCl.sub.4, vanadium tetrachloride, 
VCl.sub.4, vanadium oxytrichloride, VOCl.sub.3, titanium and vanadium 
alkoxides, wherein the alkoxide moiety has a branched or unbranched alkyl 
radical of 1 to about 20 carbon atoms, preferably 1 to about 6 carbon 
atoms. The preferred transition metal compounds are titanium compounds, 
preferably tetravalent titanium compounds. The most preferred titanium 
compound is titanium tetrachloride. 
Mixtures of such transition metal compounds may also be used and generally 
no restrictions are imposed on the transition metal compounds which may be 
included. Any transition metal compound that may be used alone may also be 
used in conjunction with other transition metal compounds. After the 
addition of the transition metal compound is completed, the non-polar 
solvent is slowly removed, e.g., by distillation or evaporation. 
The resulting free-flowing powder, referred to herein as a catalyst 
precursor, is combined with a conventional Ziegler-Natta catalyst 
activator, such as aluminum alkyls, e.g., aluminum trialkyls or aluminum 
alkyl hydrides. Other suitable activators are disclosed by John Boor, Jr., 
"Ziegler-Natta Catalysts and Polymerizations," Academic Press, New York 
(1979) pages 81-88, incorporated herein by reference. The most preferred 
activator is trimethylaluminum (TMA), although triethylaluminum (TEAL) 
which produces a somewhat less active catalyst, may also be used. We found 
that the combination of the precursor of this invention with the TMA, or, 
less preferably, TEAL, activator produces an alpha-olefin polymerization 
catalyst composition having very high activity, as compared to a catalyst 
composition comprising the same catalyst precursor and other catalyst 
activators. 
The activated catalyst composition of this invention also exhibits 
extremely good higher alpha-olefin (i.e., C.sub.3 -C.sub.10 alpha-olefin) 
incorporation properties when it is used to polymerize ethylene with such 
higher alpha-olefins. The activator is used in an amount which is at least 
effective to promote the polymerization activity of the solid catalyst 
component of this invention. If the activator is TMA or TEAL, the amount 
thereof is sufficient to give an Al:transition metal molar ratio in the 
activated catalyst composition of about 15:1 to about 1000:1, preferably 
about 20:1 to about 300:1, and most preferably about 25:1 to about 100:1. 
Without wishing to be bound by any theory of operability, it is believed 
that the catalyst composition of this invention is produced by chemically 
impregnating the support with catalyst components sequentially added to 
the slurry of the carrier in the non-polar solvent. Therefore, all of the 
catalyst synthesis chemical ingredients must be soluble in the non-polar 
solvent used in the synthesis. The order of the addition of the reagents 
may also be important since the catalyst synthesis procedure is predicated 
on the chemical reaction between the chemical ingredients sequentially 
added to the non-polar solvent (a liquid) and the solid carrier material 
or a catalyst intermediate supported by such a material (a solid). Thus, 
the reaction is a solid-liquid reaction. For example, the catalyst 
synthesis procedure must be conducted in such a manner as to avoid the 
reaction of two or more reagents in the non-polar solvent to form a 
reaction product insoluble in the non-polar solvent outside of the solid 
catalyst support. Such an insoluble reaction product would be incapable of 
reacting with the carrier or the catalyst intermediate and therefore would 
not be deposited onto the solid support of the catalyst composition. 
The catalyst precursor of the present invention is prepared in the 
substantial absence of water, oxygen, and other catalyst poisons. Such 
catalyst poisons can be excluded during the catalyst preparation steps by 
any well known methods, e.g., by carrying out the preparation under an 
atmosphere of nitrogen, argon or other inert gas. An inert gas purge can 
serve the dual purpose of excluding external contaminants during the 
preparation and removing undesirable reaction by-products resulting from 
the preparation of catalyst precursor. Purification of the non-polar 
solvent employed in the catalyst synthesis is also helpful in this regard. 
The catalyst may be activated in situ by adding the activator and catalyst 
precursor separately to the polymerization medium. It is also possible to 
combine the catalyst precursor and the activator before the introduction 
thereof into the polymerization medium, e.g., for up to about 2 hours 
prior to the introduction thereof into the polymerization medium at a 
temperature of from about -40.degree. to about 100.degree. C. 
Polymerization 
Alpha-olefins are polymerized with the catalyst prepared according to the 
present invention by any suitable process. Such processes include 
polymerizations carried out in suspension, in solution or in the gas 
phase. Gas phase polymerization reactions are preferred, e.g., those 
taking place in stirred bed reactors and, especially, fluidized bed 
reactors. 
The molecular weight of the polymer may be controlled in a known manner, 
e.g., by using hydrogen. With the catalysts produced according to the 
present invention, molecular weight may be suitably controlled with 
hydrogen when the polymerization is carried out at relatively low 
temperatures, e.g., from about 30.degree. to about 105.degree. C. This 
control of molecular weight may be evidenced by a measurable positive 
change in melt index (I.sub.2) of the polymer produced. 
The molecular weight distribution of the polymers prepared in the presence 
of the catalyst of the present invention, as expressed by the melt flow 
ratio (MFR) values, is about 20 to about 50, preferably about 20 to about 
30, for LLDPE products having a density of about 0.890 gms/cc to about 
0.940 gms/cc and an I.sub.2 (melt index) of about 0.10 to about 50. 
Conversely, HDPE products, produced with the catalysts of this invention, 
have a density of about 0.94 gms/cc to about 0.97 gms/cc, MFR values of 
about 20 to about 40, preferably about 20 to about 30, and I.sub.2 values 
of about 0.10 to about 50. As is known to those skilled in the art, such 
MFR values are indicative of a relatively narrow molecular weight 
distribution of the polymer. As is also known to those skilled in the art, 
such MFR values are indicative of the polymers especially suitable for 
injection molding applications since the polymers having such MFR values 
exhibit relatively low warpage and shrinkage on cooling of the injection 
molded products. The relatively low MFR values of the polymers prepared 
with the catalyst of this invention also indicate that they are suitable 
for the preparation of various film products since such films are likely 
to have excellent strength properties. MFR is defined herein as the ratio 
of the high load melt index (HLMI-I.sub.21.6 or I.sub.21) divided by the 
melt index (I.sub.2.16 or I.sub.2), i.e., 
##EQU1## 
where I.sub.21.6 is determined according to the procedure of ASTM 
D-1238--condition E--measured at 190.degree. C.--reported in grams per 10 
minutes (gms/10 min) and I.sub.2.16 is determined according to the 
procedure of ASTM D-1238, condition F--measured at 0.1 times the weight 
used in the I.sub.21.6 determination. 
The catalysts prepared according to the present invention are highly active 
and may have an activity of at least about 3.0-10.0 kilograms of polymer 
per gram of catalyst per 100 psi of ethylene. 
The linear polyethylene polymers prepared in accordance with the present 
invention are homopolymers of ethylene or copolymers of ethylene with one 
or more C.sub.3 -C.sub.10 alpha-olefins. Thus, copolymers having two 
monomeric units are possible as well as terpolymers having three monomeric 
units. Particular examples of such polymers include ethylene/propylene 
copolymers, ethylene/1-butene copolymers, ethylene/1-hexene copolymers, 
ethylene/1-octene copolymers, ethylene/4-methyl-1-pentene copolymers, 
ethylene/1-butene/1-hexene terpolymers, ethylene/propylene/1-hexene 
terpolymers and ethylene/propylene/1-butene terpolymers. For LLDPE film 
applications, the most preferred comonomer is 1-hexene. 
The linear low density polyethylene polymers produced in accordance with 
the present invention preferably contain at least about 60 percent by 
weight of ethylene units. 
A particularly desirable method for producing linear low density 
polyethylene polymers according to the present invention is in a fluid bed 
reactor. Such a reactor and means for operating it are described by Levine 
et al, U.S. Pat. No. 4,011,382, Karol et al, U.S. Pat. No. 4,302,566 and 
by Nowlin et al, U.S. Pat. No. 4,481,301, the entire contents of all of 
which are incorporated herein by reference. The polymer produced in such a 
reactor contains the catalyst particles because the catalyst is not 
separated from the polymer. 
The following examples further illustrate the essential features of the 
invention. However, it will be apparent to those skilled in the art that 
the specific reactants and reaction conditions used in the Examples do not 
limit the scope of the invention. 
EXAMPLE 1 
(Catalyst Precursor Synthesis) 
The catalyst precursor of this invention was synthesized as follows. 17.1 
grams of Davison 955 grade silica (previously calcined for about 16 hours 
under dry nitrogen at 600.degree. C.) was slurried under nitrogen into 200 
mls of dry hexane contained in a 500 ml round bottom flask fitted with an 
overhead stirrer and reflux condenser. Dibutylmagnesium was added dropwise 
(45 mls, 0.77M solution in heptane) and reflux continued for one hour. 
2,2,2-trichloroethanol (5.9 mls) diluted in about 60 mls of hexane was 
added and reflux continued for 40 minutes. Finally, titanium tetrachloride 
(2.0 mls) diluted in about 30 mls hexane was added and reflux continued 
for one hour. Solvents were removed by distillation to give about 22 grams 
of a free-flowing powder. 
EXAMPLE 2 (COMATIVE) 
(Catalyst Precursor Synthesis) 
A comparative catalyst precursor was synthesized in substantially the same 
manner as the catalyst precursor of Example 1, except that 
2,2,2-trichloroethanol was omitted. 
EXAMPLES 3-6 
(Polymerization Process) 
The catalyst precursors of Examples 1 and 2 were combined with 
triethylaluminum (TEAL) or with trimethylaluminum (TMA) catalyst 
activators to produce ethylene/1-hexene copolymers. A typical 
polymerization was carried out as follows in Example 3 with the catalyst 
of Example 1. At about 55.degree. C., and under a slow nitrogen purge, a 
1.6 liter stainless steel autoclave, previously heated to about 55.degree. 
C. under a purge of dry nitrogen, was filled with 400 mls of dry hexane, 
200 mls of dry 1-hexene and 3 mls of triethylaluminum (25 wt % in hexane). 
The reactor was closed, and hydrogen was introduced to raise the internal 
pressure to 20 psi. The contents of the reactor were stirred at 900 rpm 
and the temperature was increased to about 75.degree. C. 
The reactor was filled with ethylene to a total pressure of about 122 psi 
and then 0.0520 grams of Example 1 catalyst precursor, slurried in about 
50 mls of hexane, was added to the reactor. The reactor temperature was 
adjusted to 80.degree. C. and the reactor pressure was maintained with 
ethylene. 
The polymerization was continued for 37 minutes. 174 grams of polyethylene 
were obtained. The polymer contained 5.15 mole % 1-hexene and it had the 
following properties: I.sub.2 =3.14; I.sub.21 =109; I.sub.21 /I.sub.2 
=34.7; density=0.9098 gm/cc. The results of Examples 3-6 are summarized in 
Table 1. 
TABLE 1 
__________________________________________________________________________ 
Catalyst 
Example 
Precursor Productivity 
Density 
Mole % 
Reactivity 
No. of Example 
Cocatalyst 
(g. PE/g. Cat./hr.) 
(gms/cc) 
1-hexene 
ratio (r.sub.1) 
__________________________________________________________________________ 
3 1 TEAL 4370 0.910 
5.15 92 
4 2 TEAL 780 0.929 
2.60 186 
5 1 TMA 8100 0.912 
4.85 77 
6 2 TMA 1290 0.927 
2.35 206 
__________________________________________________________________________ 
The reactivity of each catalyst used to copolymerize ethylene with 1-hexene 
is dependent on the catalyst composition. The 1-hexene response is 
expressed below as a reactivity ratio, r.sub.1, defined by the equation: 
##EQU2## 
In the above formulae, subscripts E and H designate ethylene and 1-hexene, 
respectively; (C.sub.E /C.sub.H) copolymer is the mole percent of ethylene 
in the copolymer divided by the mole percent of 1-hexene in the copolymer; 
(C.sub.E /C.sub.H) monomer is the molar concentration of ethylene in the 
polymerization reactor divided by the molar concentration of 1-hexene in 
the polymerization reactor; the rate constants kEE and KEH are, 
respectively, the rates at which an ethylene or 1-hexene molecule reacts 
with an active site that previously reacted with ethylene. Thus, lower 
values of r.sub.1 indicate improved 1-hexene incorporation properties. 
The data of Table 1 indicates that the reactivity ratios of the catalyst of 
this invention (Example 1) are substantially lower than those of the 
comparative catalyst synthesized without 2,2,2-trichloroethanol (Example 
2), indicating that the catalyst of this invention has substantially 
higher activity with 1-hexene than the comparative catalyst (Example 2). 
This is confirmed by the density data of Table 1 which indicates that at 
substantially the same polymerization conditions the catalyst of this 
invention produces polymers of substantially lower density than the 
comparative catalyst. For example, the reactivity ratio data of Example 3 
indicates that with the TEAL--activated precursor of this invention 
(r.sub.1 =92) an ethylene molecule is inserted 92 times into the polymer 
molecule for every 1-hexene molecule that is inserted during the 
polymerization reaction. In the presence of the TMA activator, the 
reactivity ratio is even lower (r.sub.1 =77), indicating improved (about 
16% better) 1-hexene incorporation properties with the TMA-activated 
catalyst precursor, i.e., an ethylene molecule is inserted 77 times for 
every 1-hexene molecule that is inserted into the polymer molecule. The 
data of Table 1 for the comparative catalyst indicates a much higher 
r.sub.1 value, i.e., 186 for the TEAL-activated comparative catalyst 
(Example 4) than for the TEAL-activated catalyst of this invention, i.e., 
92 (Example 3). Hence, the catalyst of this invention reacts about twice 
as well with 1-hexene (186/92=about 2.0) as the comparative catalyst. 
It will be apparent to those skilled in the art that the specific 
embodiments discussed above can be successfully repeated with ingredients 
equivalent to those generically or specifically set forth above and under 
variable process conditions. 
From the foregoing specification, one skilled in the art can readily 
ascertain the essential features of this invention and without departing 
from the spirit and scope thereof can adapt it to various diverse 
applications.