Olefin polymerization process

A multiple stage or multiple zone process for making olefin polymers is disclosed. A single-site catalyst, preferably one that contains a heteroatomic ligand, is used in the first stage or zone, and a Ziegler-Natta catalyst is used at a higher temperature in later stages or zones. A parallel multiple zone process is also described. The processes, which can be performed adiabatically, give polymers with improved thermal processing ability.

FIELD OF THE INVENTION 
The invention relates to an olefin polymerization process. More 
particularly, the invention relates to a multiple reaction stage or zone 
process that uses a single-site catalyst in a first reaction stage or zone 
and a Ziegler-Natta catalyst in a later reaction stage or zone. The 
invention also relates to olefin polymers made by the process, which have 
improved thermal processing ability and improved mechanical properties. 
BACKGROUND OF THE INVENTION 
Interest in metallocene and non-metallocene single-site catalysts 
(hereinafter all referred to as single-site catalysts) has continued to 
grow rapidly in the polyolefin industry. These catalysts are more reactive 
than conventional Ziegler-Natta catalysts, and they produce polymers with 
improved physical properties. The improved properties include narrow 
molecular weight distribution, reduced low molecular weight extractables, 
enhanced incorporation of .alpha.-olefin comonomers, lower polymer 
density, controlled content and distribution of long-chain branching, and 
modified melt rheology and relaxation characteristics. 
Unfortunately, the uniformity of the molecular weight distribution of 
polyolefins made with single-site catalysts reduces their thermal 
processing ability. It is difficult to process these polyolefins under the 
conditions normally used for Ziegler-Natta polymers. The lower processing 
ability limits the development of single-site catalyst-based polyolefins 
because altering process conditions often requires a large capital 
investment. 
Another disadvantage of single-site catalysts is low thermal stability. 
High temperature is preferred in solution and supercritical olefin 
polymerization processes, particularly toward the end of the reaction, 
because high temperature drives the polymerization to completion and 
reduces the viscosity of the final product. Low viscosity is needed 
because the polymer is often transferred and treated to remove catalysts, 
residual monomers, or solvents. High temperature, however, deactivates 
single-site catalysts. 
Furthermore, single-site catalysts usually need a large amount of an 
alumoxane activator. The alumoxane complicates the olefin polymerization 
process and leaves high aluminum residues if not removed from the polymer. 
An important disadvantage of alumoxanes is that the large amounts 
typically present deactivate Ziegler-Natta catalysts that are used after 
or simultaneously with a single-site catalyst in an olefin polymerization. 
A method for improving thermal processing ability of polyolefins is known: 
U.S. Pat. No. 5,236,998 discloses a parallel multiple reactor process for 
producing a blend of polyethylene and a copolymer of ethylene and a 
long-chain .alpha.-olefin using a Ziegler-Natta catalyst. The polymer 
blend has a broad molecular weight distribution, and therefore, it has 
improved thermal processing ability. U.S. Pat. No. 5,747,594 discloses a 
two-stage polymerization process. In a first reactor, ethylene and an 
.alpha.-olefin are polymerized with a metallocene catalyst. The 
polymerization continues in a second reactor with a Ziegler-Natta 
catalyst. An alumoxane activator is used in the first reactor. However, we 
have found that using an alumoxane activator with a single-site catalyst 
in the first reactor can kill a Ziegler-Natta catalyst in the second 
reactor, particularly when a highly reactive, thermally stable 
Ziegler-Natta catalyst (for example, a mixture of VOCl.sub.3 and 
TiCl.sub.4) is used. 
Improved olefin polymerization processes are needed. A valuable process 
would sidestep the thermal stability problems of single-site catalysts and 
would avoid alumoxane activators. An ideal process would give olefin 
polymers with both good physical properties and excellent processing 
ability. 
SUMMARY OF THE INVENTION 
The invention is a process for making olefin polymers, particularly 
ethylene polymers that have improved thermal processing ability. The 
invention actually includes three processes: (1) a multiple stage process, 
(2) a sequential multiple zone process, and (3) a parallel multiple zone 
process. In a first stage or zone, an olefin is polymerized with a 
single-site catalyst, preferably one that contains a heteroatomic ligand, 
in the presence of a non-alumoxane activator at a temperature within the 
range of about 130.degree. C. to about 200.degree. C. In a second stage or 
zone, the polymerization is performed in the presence of a Ziegler-Natta 
catalyst at a higher temperature within the range of about 140.degree. C. 
to about 280.degree. C. In the multiple stage and sequential multiple zone 
processes, the polymerization terminates after the second stage or zone. 
In the parallel multiple zone process, the polymers made in the first and 
the second zones are transferred into a third reactor where the 
polymerization continues, optionally in the presence of a Ziegler-Natta 
catalyst. 
We surprisingly found that alumoxane compounds, which are common activators 
for single-site catalysts, cannot be used in multiple stage or multiple 
zone olefin polymerizations in which a Ziegler-Natta catalyst is used in a 
later stage or zone because the alumoxane deactivates many Ziegler-Natta 
catalysts. Moreover, the resulting olefin polymers generally have 
undesirably low molecular weights. 
Polyolefins made by the process of the invention have improved thermal 
processing ability as indicated by the melt flow index, Ml.sub.2, and the 
density. The final polymer of the process has a density less than about 
0.98 g/mL and Ml.sub.2 within the range of about 0.5 to about 300 dg/min. 
DETAILED DESCRIPTION OF THE INVENTION 
One process of the invention is a multiple stage process for making olefin 
polymers, which is conveniently performed in a single reactor. In a first 
stage, an olefin is polymerized with a single-site catalyst in a reactor 
in the presence of a non-alumoxane activator. The polymerization is 
performed at a temperature within the range of about 130.degree. C. to 
about 200.degree. C. The resulting polymer has a weight average molecular 
weight (Mw) within the range of about 5,000 to about 500,000. The 
polymerization continues in a second stage by adding a Ziegler-Natta 
catalyst and additional olefin to the reactor at a higher temperature 
within the range of about 140.degree. C. to about 280.degree. C. The final 
polymer has a density less than about 0.98 g/mL and Ml.sub.2 within the 
range of about 0.5 to about 300 dg/min. 
The invention includes a sequential multiple reaction zone process, in 
which each zone could be in a separate reactor. In a first zone, an olefin 
is polymerized with a single-site catalyst in the presence of a 
non-alumoxane activator. The temperature of the first zone is within the 
range of about 130.degree. C. to about 200.degree. C. The resulting first 
polymer has Mw within the range of about 5,000 to about 500,000. The first 
polymer is then transferred to a second reaction zone. The polymerization 
continues in the second zone at a higher temperature within the range of 
about 140.degree. C. to about 280.degree. C. in the presence of a 
Ziegler-Natta catalyst and additional olefin. The final polymer has a 
density less than about 0.98 g/mL and Ml.sub.2 within the range of about 
0.5 to about 300 dg/min. 
The invention also includes a parallel multiple reaction zone process. A 
first and second reaction zone are parallel to each other, i.e., the 
reaction mixtures are kept separate, and a third zone is used to merge the 
reaction mixtures as taught by U.S. Pat. No. 5,236,998, the teachings of 
which are incorporated herein by reference. In the first reaction zone, a 
first olefin is polymerized with a single-site catalyst in the presence of 
a non-alumoxane activator at a temperature within the range of about 
130.degree. C. to about 200.degree. C. The resulting first polymer has Mw 
within the range of about 5,000 to about 500,000. A second olefin is 
polymerized in the second reaction zone with a Ziegler-Natta catalyst at a 
temperature within the range of about 140.degree. C. to about 280.degree. 
C. The first and second olefins can be the same or different. The 
resulting second polymer has Mw within the range of about 20,000 to about 
500,000. The first and second polymers are combined and mixed in the third 
zone. Polymerization continues in the third zone, optionally in the 
presence of a third olefin which can be the same as or different from the 
first or second olefin. A Ziegler-Natta catalyst can be added to the third 
zone if there is not enough catalyst carried over from the previous zones 
to continue the polymerization. The polymerization in the third zone is 
performed at a temperature within the range of about 140.degree. C. to 
about 280.degree. C. The final polymer has a density less than about 0.98 
g/mL and Ml.sub.2 within the range of about 0.5 to about 300 dg/min. 
Suitable olefins for use in each process of the invention are C.sub.2 
-C.sub.20 .alpha.-olefins, including ethylene, propylene, 1-butene, 
1-pentene, 1-hexene, 1-octene, and mixtures thereof. Ethylene is 
preferred. Particularly, a mixture of ethylene with up to 40 wt. % of a 
higher (C.sub.5 -C.sub.20) .alpha.-olefin, for example, 1-hexene or 
1-octene, is more preferred. Incorporating a higher .alpha.-olefin into 
polyethylene improves properties. The higher .alpha.-olefin, when used, is 
preferably introduced in the first stage or zone where a single-site 
catalyst is present. An advantage of the invention is improved 
incorporation of higher .alpha.-olefins into the high molecular weight 
part of the molecular weight distribution of ethylene polymers by using a 
single-site catalyst in the first stage or zone. 
In each process of the invention, a single-site catalyst is used in the 
first stage or zone. By "single-site," we mean all of the metallocene and 
non-metallocene single-site catalysts now known. In particular, 
single-site catalysts are transition metal catalysts that are distinct 
chemical species rather than mixtures of different species. Single-site 
catalysts typically give polyolefins with characteristically narrow 
molecular weight distributions (Mw/Mn&lt;3), uniform comonomer incorporation, 
and high melt indices (Ml.sub.2 &gt;1.0) compared with polyolefins that are 
readily accessible with Ziegler-Natta catalysts. Suitable single-site 
catalysts for the first stage or zone comprise, for example, transition 
metal complexes with neutral or anionic ligands. The transition metals are 
in Groups 3-10 of the Periodic Table. The total number of anionic or 
neutral ligands satisfies the valence of the transition metal. Suitable 
ligands are, for example, substituted or unsubstituted cyclopentadienyls, 
borabenzenes, indenyls, fluorenyls, halide, alkyl, dialkylamino, siloxy, 
alkoxy, pyrrolyl, indolyl, carbazoyl, quinolinyl, pyridinyl, and 
azaborolinyl groups, or the like, and mixtures of these. Preferred 
catalysts contain a heteroatomic ligand such as borabenzene, pyrrolyl, 
quinolinyl, pyridinyl, azaborolinyl, or the like. Examples of suitable 
catalysts are bis(cyclopentadienyl)titanium dichloride, 
bis(cyclopentadienyl)zirconium dichloride, 
bis(1,2-dimethylcyclopentadienyl)zirconium dichloride, 
bis(n-butylcyclopentadienyl)zirconium dichloride, bis(indenyl)zirconium 
dichloride, ansa-dimethylsilyl-bis(cyclopentadienyl)zirconium dichloride, 
ansa-dimethylsilyl-bis(indenyl)zirconium dimethyl, 
bis(1-methylboratabenzene)zirconium dichloride, 
bis(1-methylboratabenzene)titanium dichloride, 
(cyclopentadienyl)(1-methylboratabenzene)zirconium dichloride, and the 
like. Others appear in U.S. Pat. Nos. 5,756,611, 5,637,659, 5,554,775, and 
5,539,124, and their teachings are incorporated herein by reference. 
Alumoxane compounds such as methyl alumoxane or ethyl alumoxane are not 
suitable activators for the process of the invention. When an alumoxane 
activator is used with the single-site catalyst, the alumoxane deactivates 
the Ziegler-Natta catalyst in a later stage or zone of the process. The 
resulting polymers have undesirably low molecular weight. 
Suitable non-alumoxane activators for the single-site catalysts include 
alkyl aluminums, alkyl aluminum halides, anionic compounds of boron or 
aluminum, trialkylboron and triarylboron compounds, and the like. Examples 
are triethylaluminum, trimethylaluminum, diethylaluminum chloride, lithium 
tetrakis(pentafluorophenyl) borate, triphenylcarbenium 
tetrakis(pentafluorophenyl) borate, lithium tetrakis(pentafluorophenyl) 
aluminate, tris(pentafluorophenyl) boron, tris(pentabromophenyl) boron, 
and the like. Other suitable activators are known, for example, in U.S. 
Pat. Nos. 5,756,611, 5,064,802, and 5,599,761, and their teachings are 
incorporated herein by reference. 
Activators are generally used in an amount within the range of about 0.01 
to about 100,000, preferably from about 0.1 to about 1,000, and most 
preferably from about 0.5 to about 50, moles per mole of the single-site 
catalyst. 
A Ziegler-Natta catalyst is used in the second stage or zone or third zone 
of each process of the invention. Preferred Ziegler-Natta catalysts are 
those with high thermal stability. They include titanium halides, titanium 
alkoxides, vanadium halides, and mixtures thereof, especially, TiCl.sub.3, 
TiCl.sub.4, mixtures of VOCl.sub.3 with TiCl.sub.4, and mixtures of 
VCl.sub.4 with TiCl.sub.4. Suitable Ziegler-Natta catalysts also include 
magnesium chloride-supported TiCl.sub.3, aluminum chloride-supported 
mixtures of VCl.sub.4 with TiCl.sub.4, and the like. Other suitable 
Ziegler-Natta catalysts appear in U.S. Pat. No. 4,483,938, the teachings 
of which are incorporated herein by reference, and in Eur. Pat. 222,504. 
Suitable activators for Ziegler-Natta catalysts include trialkylaluminum 
compounds and dialkylaluminum halides such as triethylaluminum, 
trimethylaluminum, diethyl aluminum chloride, and the like. These 
activators are generally used in an amount within the range of about 1:100 
to about 100:1 moles per mole of the Ziegler-Natta catalyst. 
In each process of the invention, relatively low reaction temperatures are 
preferred for the first stage or zone because the single-site catalyst has 
high reactivity even at a low temperature and, furthermore, high 
temperature deactivates this catalyst. The temperature in the first stage 
or zone is preferably in the range of about 130.degree. C. to about 
200.degree. C., more preferably from about 130.degree. C. to about 
180.degree. C., and most preferably from about 130.degree. C. to about 
150.degree. C. 
In the second stage or zone, or third zone, increased temperatures are used 
because Ziegler-Natta catalysts have low reactivity at low temperatures 
and are more thermally stable than single-site catalysts. The temperatures 
for the second stage or zone, or third zone, are preferably within the 
range of about 140.degree. C. to about 280.degree. C., more preferably 
from about 180.degree. C. to about 270.degree. C., and most preferably 
from about 200.degree. C. to about 260.degree. C. 
The process of the invention can be performed at essentially constant 
temperature in each stage or zone by heating or cooling. Preferably, 
however, it is performed adiabatically. In one adiabatic process, an 
olefin is first heated in a reactor to a desired reaction temperature, and 
a catalyst solution is then injected into the reactor to start the 
polymerization. The polymerization heat is not removed, and the 
temperature rises during the course of polymerization. An advantage of the 
adiabatic process is that the high temperature at the end of process 
drives the polymerization toward completion and reduces the viscosity of 
the final product. Low viscosity makes product recovery easier. 
The polymerization is preferably conducted under pressure. The pressure is 
preferably in the range of about 150 to about 5,000 psi, more preferably 
from about 500 to about 3,000 psi, and most preferably from about 1,000 to 
about 2,000 psi. Generally, the higher the pressure, the more productive 
the process. 
The process of the invention includes solution and supercritical 
polymerizations. Solution polymerization is preferred because it is easily 
controlled and it improves incorporation of higher .alpha.-olefins into 
polyethylene. Saturated aliphatic and aromatic hydrocarbons are suitable 
solvents. It is desirable to use a solvent having a boiling point in the 
range of about 30.degree. C. to about 150.degree. C. Solvents of lower 
boiling point create high pressure in the reaction zone, while 
high-boiling solvents are difficult to remove at the end of the process. 
Suitable solvents include pentane, hexane, heptane, octane, toluene, 
xylene, and cyclohexane, and mixtures thereof such as Isopar.RTM. G 
solvent (product of Exxon Chemical Company). 
Chain transfer agents such as hydrogen can optionally be used to control 
the molecular weight of the product produced in any of the stages or 
zones. The proportion of hydrogen used in any stage or zone can be varied. 
For example, if less hydrogen is used, a higher molecular weight polymer 
will be produced. 
Olefin polymers made by the process include polyethylene, polypropylene, 
polybutene, ethylene/propylene copolymers, ethylene/hexene copolymers, 
ethylene/octene copolymers, and the like. Particularly, the invention 
produces ethylene polymers with improved thermal processing ability. These 
polymers are widely used in the industry for making polyolefin films, 
sheets, molded parts, and other products. The olefin polymers have 
improved thermal processing ability as indicated by the melt flow index, 
Ml.sub.2, which ranges from about 0.5 to about 300 decigrams per minute 
(dg/min), preferably from about 1 to about 100 dg/min. In addition, the 
polymers have densities less than about 0.98 g/mL, preferably less than 
about 0.97 g/mL. 
While each process of the invention can produce polyolefins with improved 
thermal processing ability, each one has particular advantages. The 
multiple stage process, for example, can be practiced conveniently using a 
single reactor. Usually, however, this reactor must be cleaned out well 
between batches because residual Ziegler-Natta catalyst can adversely 
impact the performance of a single-site catalyst. 
The sequential and parallel multiple zone processes offer the advantage of 
separate reaction zones. These processes can operate either batchwise or 
continuously, and they offer great latitude in the kinds of polyolefin 
products made because the two catalyst types are used in different 
reaction zones. 
The parallel multiple zone process adds the advantage of zero contamination 
of reaction zones by either of the other catalysts. At least one zone has 
only a single-site catalyst, and at least one other zone has only a 
Ziegler-Natta catalyst; mixing of reaction products occurs in a third zone 
only.

The following examples merely illustrate the invention. Those skilled in 
the art will recognize many variations that are within the spirit of the 
invention and scope of the claims. 
EXAMPLES 1-7 
Two-Stage Process Using a Single-Site Catalyst in Stage I and Ziegler-Natta 
Catalyst A in Stage II 
Example 1 
Stage I: A two-liter, stainless-steel reactor is charged with dry, 
oxygen-free Isopar.RTM. G solvent (1000 mL, from Exxon Chemical Company). 
The reactor contents are heated to 140.degree. C. Single-site catalyst, 
ansa-dimethylsilyl-bis(indenyl)zirconium dimethyl (0.05 mmole), is mixed 
with triphenylcarbenium tetrakis(pentafluorophenyl) borate in a ratio of 
B/Zr=1.1:1.0, and the mixture is diluted with toluene to 20 mL. After 5 
minutes of mixing, the catalyst mixture is loaded into an injector. The 
reactor is pressurized with 150 psig of ethylene, and TEAL 
(triethylaluminum, 0.05 mmole in 20 mL of Isopar.RTM. G solvent) is added 
to the reactor as a scavenger. The catalyst solution is then injected. The 
polymerization starts immediately. Ethylene is supplied on demand to 
maintain the reactor pressure at 150 psig. The polymerization continues 
for 10 minutes, and then the ethylene supply is discontinued. 
Stage II: Catalyst A (a mixture of 80% VOCl.sub.3 and 20% TiCl.sub.4, 0.05 
mmole total) is combined with TEAL (0.1 mmole), and the mixture is diluted 
to 20 mL with Isopar.RTM. G solvent. After 5 minutes of mixing, the 
catalyst mixture is loaded into an injector. The reactor contents are 
heated to 147.degree. C., and the reactor is repressurized with 150 psig 
of ethylene. The catalyst solution is then injected. The polymerization 
continues at 150 psig of ethylene pressure for another 10 minutes. The 
ethylene is vented to stop the polymerization. The reactor contents are 
then transferred under N.sub.2 into a vessel containing about 1000 ppm of 
BHT (2,6-di-tert-butyl-4-methylphenol) in 1L of Isopar.RTM. G solvent and 
cooled to 25.degree. C. overnight. The polymer (38.0 g) is collected and 
dried. This amount of polymer corresponds to a productivity of 5.51 kg of 
polymer per gram of transition metal. 
Calculation of Ml.sub.2 and Density from Measured GPC Data 
In all of the following examples, the number average (Mn) and weight 
average (Mw) molecular weight and molecular weight distribution (Mw/Mn) of 
the polymer is measured by gel permeation chromatography (GPC). The data 
are collected on a Waters 150C chromatograph using 1,3,5-trichlorobenzene 
at 145.degree. C. 
The values for melt index (Ml.sub.2) shown in Table 1 are calculated using 
the following equation: log(Ml.sub.2)=20.48-3.976 log(Mw). This equation 
provides a reasonable estimate of the Ml.sub.2 of linear polyethylenes 
over a range of molecular weight distributions. (Ml.sub.2 is the melt 
index of the polymer as measured according to ASTM D-1238, Condition E.) 
The values for density shown in Table 1 are calculated by: density 
(g/mL)=1.00.chi.+0.85(1-.chi.) where .chi.=fraction of crystallinity in a 
linear polymer of weight average molecular weight Mw. Data relating 
crystallinity to Mw is taken from L. Mandelkern, Macromolecules, 5 (1972), 
147. This equation provides a good estimate for the density because no 
higher .alpha.-olefins are present during the polymerizations, and the 
polymers are linear. 
EXAMPLES 2-7 
The procedure of Example 1 is repeated, but the reaction temperatures in 
either Stage I, Stage II, or both are varied. The results are listed in 
the Table 1. 
Catalyst B Preparation 
Catalyst B is prepared using the general techniques described in U.S. Pat. 
No. 4,511,669 as follows. Butyl ethyl magnesium (5.0 kg of a 10.5 wt. % 
solution in heptane, product of Akzo-Nobel Chemicals) is placed in a 
5-gallon jacketed reactor with good temperature control. While stirring at 
25.degree. C., triethylaluminum (TEAL, 1.52 L of a 24.8 wt. % solution in 
heptane, product of Akzo-Nobel Chemicals) is added over 10 min. The 
addition cylinder is flushed with hexane (180 mL) to ensure complete 
transfer. The reaction mixture is stirred for 1 h. The reactor is then 
heated to 50.degree. C., and ethyl alcohol (2.98 L of a 2.0 M solution in 
hexane) is added over 50 min. The reactor is stirred for 2 h at 50.degree. 
C. after the addition is complete. Poly(methylhydrosiloxane) (4.46 L of a 
2.0 M solution in hexane, product of Huls Chemicals) is added over 75 min. 
The reactor is stirred for 2 h at 50.degree. C. after the addition is 
complete. Ethyl aluminum dichloride (7.56 kg of a 19.98 wt. % solution in 
hexane, product of Akzo-Nobel Chemicals) is then added over 75 min. The 
reactor is stirred for 2 h at 50.degree. C. after the addition is 
complete. Tetraisopropyltitanate (TiPT, 1.49 L of a 0.20 M solution in 
hexane, product of DuPont Chemical Co.) is added over 20 min. at 
50.degree. C. After the addition is complete, the TiPT cylinder is flushed 
with hexane (180 mL). The reactor is stirred for 2 h at 50.degree. C. 
after the addition is complete. The reactor is then cooled to 30.degree. 
C. Tri-n-octylaluminum in heptane (2.59 L of solution that contains 1.86 
wt. % aluminum, product of Akzo-Nobel Chemicals) is added over 1 h. The 
reactor is stirred for 1 h at 30.degree. C. after the addition is 
complete. The finished catalyst has a titanium concentration of about 
0.013 M. 
EXAMPLES 8-9 
Two-Stage Process Using a Single-Site Catalyst in Stage I and Ziegler-Natta 
Catalyst B in Stage II 
The procedure of Example 1 is repeated, but Ziegler-Natta Catalyst B (0.025 
mmole), instead of Catalyst A is used, and the reaction temperatures in 
either Stage I, Stage II, or both are varied. The results are listed in 
Table 1. 
TABLE 1 
__________________________________________________________________________ 
Two-Stage Polymerization Process 
Catalyst 
Temp., .degree. C. 
Cat. Polymer Properties 
Ex. 
Stage 
Stage 
Stage 
Stage 
Prod. 
Mw .times. Density 
No. I II I II kg/g 10.sup.-3 Mw/Mn Ml.sub.2 (g/mL) 
__________________________________________________________________________ 
1 SSC A 140 
147 
5.51 ND ND ND ND 
2 SSC A 140 165 13.4 108 6.2 3 0.962 
3 SSC A 140 240 8.82 29 3.8 550 0.979 
4 SSC A 180 188 8.08 120 5.8 2 0.955 
5 SSC A 180 240 5.08 64 6.4 24 0.974 
6 SSC A 200 200 7.22 77 12.0 11 0.973 
7 SSC A 220 227 2.10 58 13.3 35 0.976 
8 SSC B 140 240 9.39 32 3.9 370 0.979 
9 SSC B 180 240 3.71 78 6.0 11 0.973 
__________________________________________________________________________ 
N.D. = not determined. 
SSC = ansadimethylsilyl-bis(indenyl)zirconium dimethyl 
COMATIVE EXAMPLES 10-13 
One-Stage Process with Ziegler-Natta Catalyst A 
Comparative Example 10 
A two-liter, stainless-steel reactor is charged with dry, oxygen-free 
Isopar.RTM. G solvent (1000 mL), and the reactor is heated to 140.degree. 
C. Catalyst A (0.05 mmole) is combined with TEAL (0.1 mmole), and the 
mixture is diluted to 20 mL with Isopar.RTM. G solvent. After 5 minutes of 
mixing, the catalyst mixture is loaded into an injector. The reactor is 
pressurized with 150 psig of ethylene, and then the catalyst solution is 
injected. The polymerization starts immediately, and ethylene is supplied 
on demand to maintain the reactor pressure at 150 psig. The polymerization 
continues for 10 minutes, and the ethylene supply is then discontinued. 
The reactor contents are transferred under N.sub.2 into a vessel 
containing about 1000 ppm of BHT in 1L of Isopar.RTM. G solvent, and the 
mixture cools to 25.degree. C. overnight. The polymer (22.4 g) is dried 
and collected. Catalyst productivity is 8.9 kg of polymer per gram of 
transition metal. Melt index is measured according to ASTM D-1238, 
Condition E and Condition F. (An actual measurement rather than a 
calculation, as is used for Examples 1-9.) Ml.sub.2 is the melt index 
measured with a 2.16 kg weight (Condition E). The high-load melt index 
(HLMI) is the melt index measured with a 21.6 kg weight (Condition F). The 
melt flow ratio (MFR) is the ratio of HLMI to Ml.sub.2 and is an 
indication of the molecular weight distribution. The polymer has Mw: 
257,000, Mw/Mn: 6.1, Ml.sub.2 : 0.01 dg/min, and MFR: 83. 
COMATIVE EXAMPLES 11-13 
The procedure of Comparative Example 10 is repeated, but the reactor 
contents are heated to the desired reaction temperature prior to injecting 
the catalyst. Reaction temperatures, catalyst productivities, and polymer 
properties are listed in Table 2. 
COMATIVE EXAMPLES 14-17 
One-Stage Process with Ziegler-Natta Catalyst B 
Comparative Example 14 
The polymerization of Comparative Example 10 is repeated, but Catalyst B 
(0.025 mmole) is used instead of Catalyst A. The polymer (36.5 g) is 
collected. Catalyst productivity: 29.0 kg of polymer per gram of 
transition metal. The polymer has Mw: 158,000, Mw/Mn: 4.2, Ml.sub.2 : 0.15 
dg/min, and MFR: 69. 
COMATIVE EXAMPLES 15-17 
The procedure in Comparative Example 14 is repeated, but the reaction 
temperature is varied. The results are listed in Table 2. 
COMATIVE EXAMPLES 18-21 
One-Stage Process with Single Site Catalyst 
COMATIVE EXAMPLE 18 
The procedure of Comparative Example 10 is repeated, but a single-site 
catalyst, ansa-dimethylsilyl-bis(indenyl)zirconium dimethyl, (0.049 
mmole), is used instead of Catalyst A. The catalyst is mixed with 
triphenylcarbenium tetrakis- (pentafluorophenyl) borate in a ratio of 
B/Zr=1.1:1.0, and the mixture is diluted with toluene to 20 mL. TEAL (0.05 
mmole in 20 mL of Isopar.RTM. G solvent) is introduced into the reactor as 
a scavenger before the catalyst mixture is injected. The polymer (55.2 g) 
is collected. Catalyst productivity: 22.4 kg of polymer per gram of 
transition metal. The polymer has Mw: 27,000, Mw/Mn: 3.4, and Ml.sub.2 : 
280 dg/min. 
COMATIVE EXAMPLES 19-21 
The procedure of Comparative Example 18 is repeated, but the reaction 
temperature is varied. The results are listed in Table 2. 
TABLE 2 
______________________________________ 
Comparative One-Stage Polymerization Process 
Polymer Properties 
Ex. Temp. Prod., 
Mw .times. 
No. Catalyst .degree. C. kg/g 10.sup.-3 Mw/Mn Ml.sub.2 MFR 
______________________________________ 
C10 A 140 8.9 257 6.1 0.01 83 
C11 A 180 7.1 190 6.9 0.03 62 
C12 A 220 10.0 89 4.8 N.D. N.D. 
C13 A 240 6.3 77 4.8 4.1 41 
C14 B 140 29.0 158 4.2 0.15 69 
C15 B 180 42.6 108 5.2 1.0 51 
C16 B 220 33.1 60 4.6 10.4 32 
C17 B 240 18.5 43 3.4 51.2 39 
C18 SSC 140 22.4 27 3.4 280 N.D. 
C19 SSC 180 21.7 9 2.9 &gt;2000 N.D. 
C20 SSC 220 4.8 11 3.5 &gt;2000 N.D. 
C21 SSC 240 2.8 11 4.8 &gt;2000 N.D. 
______________________________________ 
N.D. = not determined. 
SSC = ansadimethylsilyl-bis(indenyl)zirconium dimethyl 
EXAMPLE 22 
Sequential Multiple Zone Process 
In a first two-liter, stainless-steel reactor, 1000 mL of oxygen-free 
Isopar.RTM. G solvent and 40 grams of octene are introduced. The reactor 
is heated to 140.degree. C., and enough ethylene is added to bring the 
reactor pressure to 150 psig. Bis(methylborabenzene) zirconium dimethyl 
(0.05 mmole, prepared according to U.S. Pat. No. 5,554,775) is mixed with 
0.055 mmole of tri(n-butyl)ammonium tetrakis(pentafluorophenyl) borate 
(prepared according to U.S. Pat. No. 5,599,761). The mixture is diluted 
with toluene to 20 mL, and is loaded into an injector. The catalyst 
solution is then injected into the reactor to start the polymerization. 
Ethylene supply continues to maintain the reactor pressure at 150 psig. 
The polymerization is carried out for 10 minutes, and the ethylene supply 
is discontinued. The reactor is sampled to measure the properties of the 
first polymer, which is expected to have a Mw within the range of about 
50,000 to about 200,000, and to contain about 2 to about 10 wt. % of 
octene monomeric units. 
In a second two-liter, stainless-steel reactor, 0.05 mmole of Catalyst A is 
introduced along with triethylaluminum (TEAL, 0.1 mmole). The first 
polymer is transferred to the second reactor. The polymerization continues 
by adding additional ethylene to maintain the reactor pressure at 150 
psig. The polymerization is carried out at 200.degree. C. for 10 minutes. 
Calcium stearate (1000 ppm) is added to terminate the polymerization, and 
the product is then transferred under N.sub.2 into a vessel containing 250 
ppm of Irganox.TM. 1010 antioxidant (product of Ciba-Geigy) and cooled to 
25.degree. C. The final polymer is dried and collected. It is expected to 
have a density less than 0.98 g/mL and Ml.sub.2 within the range of about 
0.5 to about 300 dg/min. 
EXAMPLE 23 
Parallel Multiple Zone Process 
In a first two-liter, stainless-steel reactor, 1000 mL of oxygen-free 
Isopar.RTM. G solvent and 40 grams of octene are introduced. The reactor 
is heated to 140.degree. C., and enough ethylene is added to bring the 
reactor pressure to 150 psig. Bis(methylborabenzene) zirconium dimethyl 
(0.05 mmole, prepared according to U.S. Pat. No. 5,554,775) is mixed with 
0.055 mmole of tri(n-butyl)ammonium tetrakis(pentafluorophenyl) borate 
activator (prepared according to U.S. Pat. No. 5,599,761). The mixture is 
diluted with toluene to 20 mL, and is loaded into an injector. The 
catalyst solution is then injected into the reactor to start the 
polymerization. Ethylene supply continues to maintain the reactor pressure 
at 150 psig. The polymerization is carried out for 10 minutes, and the 
ethylene supply is then discontinued. The reactor is sampled to measure 
the properties of the first polymer, which is expected to have a Mw in the 
range of about 50,000 to about 200,000, and to contain about 2 to about 10 
wt. % of octene monomeric units. 
In a second two-liter, stainless-steel reactor, which is parallel to the 
first reactor (set-up as taught in U.S. Pat. No. 5,236,998), 1000 mL of 
Isopar.RTM. G solvent, 0.05 mmole of Catalyst A, and 0.1 mmole of TEAL are 
introduced. Ethylene is added to bring the reactor pressure to 150 psig. 
The reactor contents are heated to 200.degree. C., and the polymerization 
is carried out at this temperature for 10 minutes. The reactor is sampled. 
The second polymer (from the second reactor) is expected to have a Mw 
within the range of about 100,000 to about 250,000. 
The first and the second polymers are transferred to a third reactor. The 
reactor contents are mixed well and heated to 200.degree. C. Ethylene is 
added to bring the pressure to 150 psig. Catalyst A (0.050 mmole), and 0.1 
mmole of triethylaluminum are introduced to the reactor. The 
polymerization continues for 10 minutes at 200.degree. C. Calcium stearate 
(1000 ppm) is then added to terminate the polymerization. The final 
product is transferred under N.sub.2 into a vessel containing 250 ppm of 
Irganox.TM. 1010 antioxidant and cooled to 25.degree. C. The final polymer 
is dried and collected. It is expected to have a density less than 0.98 
g/mL and Ml.sub.2 within the range of about 0.5 to about 300 dg/min. 
The preceding examples are meant only as illustrations; the following 
claims define the scope of the invention.