U.S. patent application number 10/077300 was filed with the patent office on 2002-08-22 for methods of production of ethylene copolymers having narrow composition distributions and high melting temperatures.
This patent application is currently assigned to The Board of Trustees of the Leland Stanford Junior University. Invention is credited to Kravchenko, Raisa L., Maciejewski Petoff, Jennifer L., Waymouth, Robert M..
Application Number | 20020115805 10/077300 |
Document ID | / |
Family ID | 27371813 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020115805 |
Kind Code |
A1 |
Waymouth, Robert M. ; et
al. |
August 22, 2002 |
Methods of production of ethylene copolymers having narrow
composition distributions and high melting temperatures
Abstract
A copolymer of ethylene and at least one comonomer containing at
least 4 carbon atoms is characterized by a polydispersity greater
than 2, a broad melting point transition as measured by
differential scanning calorimetry, and a narrow composition
distribution. Ethylene/C.sub.4+ copolymers also may show at least
one peak melting point above the peak melting point of a random
copolymer of the same monomer unit composition. These copolymers
are made by contacting ethylene and a comonomer under
polymerization conditions in the presence of a suitable fluxional
catalyst system.
Inventors: |
Waymouth, Robert M.; (Palo
Alto, CA) ; Maciejewski Petoff, Jennifer L.; (Belle
Mead, NJ) ; Kravchenko, Raisa L.; (Wilmington,
DE) |
Correspondence
Address: |
Jacques M. Dulin, Esq.
Innovation Law Groupsm
Suite 101
851 Fremont Ave.
Los Altos
CA
94024
US
|
Assignee: |
The Board of Trustees of the Leland
Stanford Junior University
|
Family ID: |
27371813 |
Appl. No.: |
10/077300 |
Filed: |
February 15, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10077300 |
Feb 15, 2002 |
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09349557 |
Jul 8, 1999 |
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09349557 |
Jul 8, 1999 |
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09227228 |
Jan 8, 1999 |
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60071050 |
Jan 9, 1998 |
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60137107 |
Jun 2, 1999 |
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Current U.S.
Class: |
526/160 ;
502/152; 526/348.5; 526/348.6; 526/943 |
Current CPC
Class: |
C08F 10/00 20130101;
C08F 110/02 20130101; C08F 210/16 20130101; C08F 210/14 20130101;
C08F 2500/03 20130101; C08F 2500/06 20130101; C08F 4/65925
20130101; C08F 2500/08 20130101; C08F 2500/01 20130101; C08F
2500/20 20130101; C08F 4/63925 20130101; C08F 2500/06 20130101;
C08F 2500/03 20130101; C08F 2500/06 20130101; C08F 2500/03
20130101; C08F 2500/12 20130101; C08F 210/16 20130101; C08F 2500/10
20130101; C08F 210/14 20130101; C08F 2500/03 20130101; C08F 2500/20
20130101; C08F 2500/20 20130101; C08F 210/16 20130101; C08F 2500/20
20130101; C08F 2500/06 20130101; C08F 4/65925 20130101; C08F
2500/06 20130101; C08F 210/06 20130101; C08F 2500/12 20130101; C08F
2500/20 20130101; C08F 2500/20 20130101; C08F 210/14 20130101; C08F
210/16 20130101; C08F 2500/03 20130101; C08F 2500/04 20130101; C08F
110/02 20130101; C08F 10/00 20130101; C08F 210/06 20130101; C08F
110/06 20130101; C08F 4/65912 20130101; C08F 210/16 20130101; C08F
210/06 20130101; C08F 210/16 20130101; Y10S 526/943 20130101; C08F
210/06 20130101; C08F 110/06 20130101; C08F 110/06 20130101; C08F
210/16 20130101; C08F 4/65927 20130101; C08F 10/02 20130101; C08F
4/63912 20130101; C08F 10/02 20130101; C08F 210/16 20130101; C08F
210/16 20130101; C08F 210/06 20130101 |
Class at
Publication: |
526/160 ;
526/943; 526/348.5; 526/348.6; 502/152 |
International
Class: |
C08F 004/44 |
Claims
1. A copolymer of ethylene with at least one comonomer containing
at least 4 carbon atoms characterized by a polydispersity greater
than 2, a broad melting point transition as measured by
differential scanning calorimetry, and a narrow composition
distribution.
2. A copolymer of claim 1 wherein the comonomer is at least one
olefin containing from 4 to about 12 carbon atoms.
3. A copolymer of claim 1 wherein the comonomer is an alpha-olefin
containing 4 to about 8 carbon atoms.
4. A copolymer of claim 1 wherein the comonomer is 1-butene,
1-pentene, 1-hexene, 1-octene, or 4-methyl-1-pentene, or mixtures
thereof.
5. A copolymer of claim 1 wherein the comonomer is 1-hexene.
6. A copolymer of claim 1 wherein the melting point transition is
greater than about 50.degree. C.
7. A copolymer of claim 1 wherein the melting point transition is
greater than about 100.degree. C.
8. A copolymer of claim 1 wherein the polydispersity is greater
than about 3.
9. A copolymer of claim 1 wherein the polydispersity is between
about 4 and about 12.
10. A copolymer of claim 1 wherein the solvent-fractionated
composition distribution is less than or equal to 15%.
11. A copolymer of claim 1 wherein the solvent-fractionated
composition distribution is less than or equal to 12% and the
comonomer is 1-butene, 1-pentene, 1-hexene, 1-octene, or
4-methyl-1-pentene, or mixtures thereof.
12. A copolymer of claim 1 wherein the solvent-fractionated
composition distribution is less than or equal to 10%.
13. A copolymer of claim 1 wherein the comonomer is 1-butene,
1-hexene, or 1-octene, the composition distribution is less than
12%, the melting point transition is greater than 75.degree. C.,
and the polydispersity is greater than 3.
14. A copolymer of claim 1 which is elastomeric.
15. A copolymer of claim 1 which is plastomeric.
16. A copolymer of claim 1 in which the molecular
weight-fractionated composition distribution of is less than about
5%.
17. A copolymer of claim 1 which contains about 1 to about 50 mole
percent of comonomer.
18. A copolymer of claim 17 which contains up to about 40 mole
percent of comonomer.
19. A copolymer of claim 1 which contains up to about 10 mole
percent comonomer.
20. A copolymer of claim 19 which contains from 1 to about 5 mole
percent comonomer.
21. The copolymer of claim 1, wherein the copolymer is formed as a
pellet.
22. The copolymer of claim 21, wherein said pellet contains polymer
stabilizers.
23. The copolymer of claim 1, wherein the copolymer is formed as a
molded or extruded article.
24. The copolymer of claim 23, wherein said article is a pipe or a
container.
25. The copolymer of claim 1, wherein the copolymer is formed as a
film.
26. The copolymer of claim 25, wherein said film has a thickness
from about 0.1 to about 100 mil.
27. A film of claim 26 with a thickness from 0.5 to 20 mil.
28. A copolymer of ethylene with at least one comonomer containing
at least 4 carbon atoms characterized by at least one peak melting
point above the peak melting point of a random copolymer of the
same monomer unit composition.
29. A copolymer of claim 28 in which at least one comonomer
contains 6 carbon atoms.
30. A copolymer of claim 28 which is an elastomer.
31. A copolymer of claim 28 which is a plastomer.
32. A copolymer of claim 31, wherein the copolymer is formed as a
film.
33. A copolymer of claim 28 in which the solvent-fractionated
composition distribution is less than about 15%.
34. A copolymer of claim 33 in which at least one comonomer is an
alpha olefin which contains 4 to about 10 carbon atoms.
35. A copolymer of claim 34 A copolymer of claim 1 which contains
from about 1 to about 40 mole percent of comonomer.
36. A copolymer of claim 35 which has a solvent-fractionated
composition distribution less than about 12%.
37. A copolymer of claim 36 which has a polydispersity of above 2
to about 12.
38. A copolymer of claim 37 which contains up to 10 mole percent
comonomer.
39. A copolymer of claim 38 which is plastomeric and which contains
from 1 to about 5 mole percent comonomer.
40. A method to make a copolymer of claim 1 wherein ethylene and a
comonomer are contacted under polymerization conditions in the
presence of a fluxional catalyst system.
41. The method of claim 40 in which the metallocene component of
the fluxional catalyst system has more than two symmetry
states.
42. The method of claim 40 in which the fluxional catalyst system
contains a substituted 2-arylindenyl metallocene component.
43. The method of claim 40 wherein hydrogen is a component of the
catalyst system in an amount sufficient form a plastomeric
copolymer product.
44. The method of claim 40 in which the metallocene component of
the fluxional catalyst system contains zirconium or hafnium.
45. The method of claim 44 in which the metallocene component of
the fluxional catalyst system contains hafnium.
46. The method of claim 40 wherein wherein the fluxional catalyst
system contains a metallocene component with at least on ligand
with the structure: 5where R.sub.4-R.sub.14 may be the same or
different substituents comprising hydrogen, halogen, or aryl,
hydrocarbyl, silahydrocarbyl, or halohydrocarbyl moities containing
up to 12 carbon atoms.
47. The method of claim 46 wherein R5 and R7 are bulky
sustituents.
48. The method of claim 47 wherein wherein R5 and R7 are t-butyl,
trifluoromethyl, or trimethylsilyl, or combinations thereof.
49. A method to make a copolymer of claim 28 wherein wherein
ethylene and a comonomer are contacted under polymerization
conditions in the presence of a fluxional catalyst system.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of Application
Ser. No. 09/227,228 filed Jan. 8, 1999, which claimed benefit of
Provisional Application No. 60/071,050 filed January 9, 1998; and
further this application claims benefit of Provisional Application
No. 60/137,107 filed Jun. 2, 1999, all of which are incorporated by
reference herein.
FIELD OF THE INVENTION
[0002] This invention relates to thermoplastic polyolefins. More
particularly, this invention relates to copolymers of ethylene with
C.sub.4+ olefin monomers which typically contain blocky structures
as shown by peak melting temperatures above those measured in
corresponding random copolymers with similar monomer composition,
and to methods of production by use of fluxional metallocane
catalysts.
BACKGROUND OF THE INVENTION
[0003] Thermoplastic olefin polymers represent a significant
worldwide market with millions of tons of these polymers produced
and sold each year. Copolymers of ethylene with C.sub.4+ monomers
are a substantial fraction of the worldwide olefin polymer
production, especially in use as films. Although the bulk of
ethylene polymers are thermoplastics, there is a growing further
need for elastomeric thermoplastic olefin polymers.
[0004] Copolymers of ethylene with higher (C.sub.4+) olefin
monomers are well known and used in the art. Among these are linear
low density polyethylenes conventionally produced as a copolymer of
ethylene with 1-butene or 1-octene using traditional Ziegler-Natta
catalyst systems. These materials typically have broad
polydispersities, and broad composition distributions.
[0005] Some of these ethylene-C.sub.4+ copolymers have a
particularly broad range of application as elastomers. There are
generally three families of elastomers made from such copolymers.
One class is typified by ethylene-propylene copolymers (EPR) which
are saturated compounds, optimally of low crystallinity, requiring
vulcanization with free-radical generators to achieve excellent
elastic properties. Another class of elastomer is typified by
ethylene-propylene terpolymers (EPDM), again optimally of low
crystallinity, which contain a small amount of a non-conjugated
diene such as ethylidene norbornene. The residual unsaturation
provided by the diene termonomer allows for vulcanization with
sulfur, which then yields excellent elastomeric properties.
[0006] Yet a third class is typified by ethylene-alpha olefin
copolymers of narrow composition distribution which possess
excellent elastomeric properties even in the absence of
vulcanization. For example U.S. Pat. No. 5,278,272, to Dow
describes a class of substantially linear polyolefin copolymer
elastomers with narrow composition distribution and excellent
processing characteristics. These are produced with conventional
metallocene-based catalyst systems which have narrow
polydispersities, narrow composition distributions and melting
point ranges corresponding to random copolymers. Representatives of
these metallocene copolymers are ethylene/1-butene copolymers sold
as Exact' brand by Exxon Chemical and ethylene/1-octene copolymers
sold as Engage' brand by Dow Chemical. One of the limitations of
these latter class of elastomers is their low melting temperature
which limits their high temperature performance.
DISCLOSURE OF THE INVENTION
[0007] Summary, Objects and Advantages
[0008] This invention relates to copolymers of ethylene with
C.sub.4+ olefin monomers which may be thermoplastics or elastomers.
Particularly, these copolymers typically are formed from a
fluxional catalyst system which creates properties consistent with
a blocky structure. A polymer chain with a blocky structure will
contain segments of differing compositional microstructure. Thus,
in an ethylene/hexene copolymer of this invention, the evidence
indicates ethylene homopolymer blocks are distributed in the
polymer chain with adjacent segments of ethylene/hexene copolymer.
Since ethylene homopolymer segments will form regions of
polyethylene crystallinity while ethylene/hexene copolymer segments
will be amorphous, the polymer as a whole contains regions of
polyethylene crystallinity interspersed with amorphous regions to a
greater extent than would be observed in a copolymer of ethylene
with randomly dispersed comonomer. Typically the upper peak melting
temperatures for the copolymers of this invention are higher than
corresponding random copolymers, although the melting transition is
relatively broad and typically has multimodal or bimodal melting
temperature peaks. This data indicates that the polymers of the
present invention contain larger, more thermodynamically stable
crystals and longer ethylene sequences than that present in a
random ethylene polymer.
[0009] The broad melting range exhibited by the copolymers of this
invention extending to higher melting temperatures than random
polymers of similar branching, indicates the former crystallize to
give a broader range of crystal types (high and low melting). The
high melting crystals are a result of the non-random comonomer
incorporation allowing the formation of longer runs of ethylene
homopolymer sequences than occurs in random versions. The
comonomer, such as hexene, interrupts crystallization and, thus,
the largest and most stable crystal into which a polymer chain can
crystallize is defined by the longest ethylene unit run length
present.
[0010] Further, the copolymers of the invention show a narrow
compositional distribution among fractions separated by
crystallinity or molecular weight. The copolymers of this invention
show improved optical properties, such as clarity and reduced haze
in films, as follows from a narrower composition distribution. The
copolymers of the invention also exhibit a relatively broad
polydisperity, a property which results in superior
processibility.
[0011] In another aspect of this invention, the olefin copolymers
of the invention are characterized by low glass transition
temperatures, melting points above about 90.degree. C., high
molecular weights, and a narrow composition distribution between
chains. The copolymers of the invention are novel reactor blends
that can be sequentially fractionated into fractions of differing
crystallinities. These fractions nevertheless show compositions of
comonomers which differ by less than 15% from the parent reactor
blend. The invention also relates to a process for producing such
copolymers by using unbridged fluxional metallocene catalysts that
are capable of interconverting between states, each state having
different copolymerization characteristics, i.e., each state having
a different relative rate of insertion of a given ethylene or
C.sub.4+ monomer into the growing copolymer chain and preferential
selectivity for different monomers under particular reaction
conditions.
[0012] An important object of this invention is to provide methods
of production of a novel class of polyolefin copolymers with a
combination of commercially important physical characteristics,
including: a molecular weight distribution, M.sub.w/M.sub.n>2, a
narrow composition distribution, </=15%, high melting point
index, melting points greater than about 90.degree. C., and
typically above the melting temperature of a random copolymer
having the same monomer unit composition. It is a further object of
this invention to produce a novel family of crystallizable,
high-melting polyolefin copolymers having a narrow composition
distribution where the melting point of the polymer is greater than
about 90.degree. C. It is a further object of this invention to
produce a class of high-melting, multiblock, blend, and
multiblock/blend polyolefin copolymer elastomers. These novel
polymers are useful as thermoplastic materials as well as
compatibilizers for other polyolefin blends.
[0013] The copolymers of this invention are produced using a new
family of fluxional metallocene-based catalysts first described in
U.S. Pat. No. 5,594,080, incorporated by reference herein. These
catalysts produce blocky structures in the polymer chain which
yield polymer products having a combination of properties which is
advantageous for multiple use applications including films. This
combination of properties include a narrow composition
distribution, broad polydispersity, and a broad melting transition
with an upper melting peak which typically is higher than a
randomly distributed copolymer with the same monomer unit
composition.
[0014] Products made from the copolymers of this invention benefit
from the products improved processibility of the polymer, higher
temperature performance range, and uniformity. Applications include
films, including heat sealable films, and molded products. More
particularly with respect to films, films can be produced with
improved optical properties such as low haze and improved
clarity.
[0015] The copolymers of the Invention can be characterized as
copolymers of ethylene and at least one comonomer containing at
least 4 carbon atoms having a polydispersity greater than 2, a
broad melting point transition as measured by differential scanning
calorimetry, and a narrow composition distribution.
Ethylene/C.sub.4+ copolymers of the invention also may show at
least one peak melting point above the peak melting point of a
random copolymer of the same monomer unit composition. These
copolymers are made by contacting ethylene and a comonomer under
polymerization conditions in the presence of a suitable fluxional
metallocene catalyst system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a stereoisomeric representation of unbridged
metallocenes used in this invention having different substituents
in the positions R.sub.1 through R.sub.10 with the arrows showing
the interconversion between states A and B in which the reactivity
toward ethylene, r.sub.E, and other alpha olefins differs in the
two states;
[0017] FIG. 2 shows four possible coordination geometries for
unbridged metallocenes used in this invention, with the circles
representing coordination sites for olefin insertion;
[0018] FIG. 3 shows superimposed DSC thermograms for
ethylene-1-hexene copolymers produced with differing amounts of
hydrogen, wherein the trace (a) product had no H.sub.2 added; trace
(b) product has 2.5 mmol H.sub.2 added; and trace (c) product has
5.0 mmol H.sub.2 added;
[0019] FIG. 4 shows a DSC profile for an ethylene-1-hexene
copolymer containing 72 mol % ethylene, wherein the top trace is a
standard DSC and the bottom is a SFT trace;
[0020] FIG. 5 shows melting temperature vs. composition plotted for
the ethylene-1-hexene copolymer of Example 19 with its solvent
fractions (cf. Table 9), and by way of comparison also plotted is
data for random alpha-olefin copolymers; and
[0021] FIG. 6 shows melting temperature vs. composition plotted for
the ethylene-1-hexene hexene copolymer of Example 7 with its
solvent fractions (cf. Table 5), and by way of comparison also
plotted is data for random alpha-olefin copolymers.
DETAILED DESCRIPTION INCLUDING THE BEST MODE OF CARRYING OUT THE
INVENTION
[0022] The following detailed description illustrates the invention
by way of example, not by way of limitation of the principles of
the invention. This description will clearly enable one skilled in
the art to make and use the invention, and describes several
embodiments, adaptations, variations, alternatives and uses of the
invention, including what are presently believed to be the best
modes of carrying out the inventions.
[0023] In this regard, the invention is illustrated in the several
examples, and is of sufficient complexity that the many aspects,
interrelationships, and sub-combinations thereof simply cannot be
fully illustrated in a single example. For clarity and conciseness,
several of the examples show, or report only aspects of a
particular feature or principle of the invention, while omitting
those that are not essential to or illustrative of that aspect.
Thus, the best mode embodiment of one aspect or feature may be
shown in one example or test, and the best mode of a different
aspect will be called out in one or more other examples, tests,
structures, formulas, or discussions.
[0024] All publications, patents and applications cited in this
specification are herein incorporated by reference as if each
individual publication, patent or application had been expressly
stated to be incorporated by reference.
[0025] We have unexpectedly found that it is possible to prepare
high melting polyolefins of narrow composition distribution using a
class of unbridged, fluxional metallocenes as olefin polymerization
catalysts.
[0026] For convenience, certain terms used throughout the
specification are defined below.
[0027] The symbols "</=" and ">/=" mean "less than or equal
to" and "greater than or equal to", respectively.
[0028] "Multiblock" polymer or copolymer means a polymer comprised
of multiple block sequences of monomer units where the structure or
composition of a given sequence differs from that of its neighbor.
Furthermore, a multiblock copolymer as defined herein will contain
a given sequence at least twice in every polymer chain.
[0029] The term "composition distribution" is the variation in
co-monomer composition between different polymer chains and is
described as a difference, in mole percent, of a given weight
percent of a fractionated sample from the mean mole percent
composition. The distribution need not be symmetrical around the
mean; when expressed as a number (for example 10%), that number
represents the larger of the distributions from the mean.
[0030] The term "elastomeric" refers to a material which tends to
regain its shape after extension, such as one which exhibits a
positive power of recovery after 100, 200 and 300% elongation.
[0031] The term "melting point index", also referred to as
MPI=T.sub.m/X.sub.c, means the ratio of the melting point of the
copolymer, Tm, to the mole fraction of the crystallizable
component, X.sub.c.
[0032] By "crystallizable component," we mean a monomer component
whose homopolymer is a crystalline polymer. For ethylene copolymers
exhibiting polyethylene crystallinity, the crystallizable component
is ethylene.
[0033] The melting point (Tm) is taken as a maximum in a melting
endotherm, as determined by differential scanning calorimetry
(DSC). A polymer may have more than one T.sub.m, if there are more
than one maxima in the DSC thermogram.
[0034] Copolymers of this invention are characterized by a broad
melting range as exhibited in a DSC thermogram, a narrow
composition distribution over fractions separated by crystallinity
or molecular weight; and a relatively broad molecular weight
distribution (or polydispersity). This combination of
characteristics produce an ethylene copolymer product having
distinct and commercially significant properties.
[0035] The copolymers of this invention are formed from ethylene
and an olefin monomer containing from 4 up to about 20 carbon atoms
and typically from 4 to about 10 carbon atoms, herein termed a
"C.sub.4+" monomer. Preferable comonomers contain from 4 to 8
carbons. Representative comonomers include 1-butene, 1-pentene,
1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene. Butene,
hexene, octene monomers are preferred with hexene being the most
preferred. Mixtures of comonomers may be used.
[0036] The amount of comonomer which is incorporated into the
copolymers of this invention may vary depending upon the properties
desired. Typically, copolymers of this invention contain up to
about 50 mole % (preferably up to 40 mole %) of comonomers. Typical
copolymers may contain up to 30 or up to 10 mole percent of
comonomers.
[0037] For highly crystalline polymers of higher density,
copolymers of this invention may contain up to 10 and preferably up
to 5 mole percent comonomers. Typically, the minimum amount of
comonomer used in this invention depends on the amount of comonomer
which is needed to alter the properties of ethylene homopolymer.
This amount typically is greater than about one mole percent and
often is more than about two mole percent.
[0038] The properties of the copolymer produced according to this
invention may vary from elastomeric to those of a thermoplastic.
Copolymers of the invention containing more than about 10 mole
percent comonomer content typically have elastomeric properties.
However, addition of hydrogen to the polymerization reaction can
result in production of a plastomer having the same monomer
composition as a copolymer which is an elastomer when hydrogen is
not added.
[0039] The ethylene copolymer products of the invention typically
exhibit bimodal or multimodal crystalline melting temperature
transitions with a broad region of crystalline melting. Although a
crystalline melting temperature, T.sub.m, may be assigned to the
highest temperature peak in a DSC thermogram as illustrated in FIG.
3, a copolymer of this invention typically shows a broad melting
temperature region and a low temperature melting point peak. A
broad melting point range in a DSC thermogram indicates a
distribution of crystals of different sizes and thermodynamic
stabilities and correspondingly a distribution of crystallizable
sequences in the polymer chains. Peaks in the thermogram indicate
increased concentrations of crystals with similar stabilities. In
some instances, there may be separated bimodal melting ranges. This
indicates that most of the polymer chains have higher
concentrations of high and low melting crystals and a lower
concentration of crystals that melt at intermediate
temperatures.
[0040] Melting temperature data reported in the Tables include
multiple crystalline melting points. In these cases, (especially
for copolymers having <95 mol % ethylene) the highest reported
T.sub.m is above the melting point which would be expected for a
copolymer with the same amount of randomly distributed comonomer.
For very high ethylene-content copolymers (ethylene more than about
95 mol %), the melting temperature of a random copolymer will
approach, or may be within experimental variation, of the highest
T.sub.m observed in a blocky copolymer of this invention. However,
the copolymers of this invention, even at this high ethylene
content, exhibit broad, and sometimes multimodal, melting peaks,
and are therefore clearly different in nature than random
copolymers.
[0041] Polymers of this invention show a broad melting point range
from the minimum to maximum melting temperature of from over
50.degree. C. more than to 150.degree. C. or above. Preferably,
polymers may have melting temperature ranges of above 75.degree. C.
(often greater than 100.degree. C.) up to about a 150.degree. C.
range. There may be multimodal, usually bimodal, maxima (reported
as T.sub.m's) in the DSC thermograms within these broad ranges.
[0042] Molecular weight distribution (or polydispersity) is
reported as weight average molecular weight divided by the number
average molecular weight (Mw/Mn) as measured by gel permeation
chromatography (GPC) techniques. In typical metallocene catalyst
produced polymers, the polydispersity is narrow, M.sub.W/M.sub.n=2.
processing equipment and many times results in higher throughput of
the polymer in the process. An ability to increase throughput has
significant economic advantages since process unit capacity
increases without a need to purchase additional equipment.
[0043] Copolymers of this invention typically have molecular weight
distributions (Mw/Mn) or polydispersities above 2 and usually above
3. Useful polydispersities may range up to 12 or above. Preferable
copolymers of this invention have polydispersities ranging from
about 3 to about 10 and more preferably from about 4 to about
9.
[0044] Another aspect of this invention is that the distribution of
monomer unit composition is narrow in product fractions that are
separated by crystallinity or molecular weight. For solvent
fractionated products, which generally separate polymer chains by
crystallinities, the range of co-monomer composition distribution
typically varies by less than about 15 mole percent (15 mole %),
preferably varies by less than about 12 mole %, and more preferably
varies by less than 8-10 mole %. Even though the composition
distribution is narrow for these fractions, the melting transitions
measured by DSC may vary substantially among the solvent fractions.
The solvents used for fractionation include diethylether (ether),
hexanes (saturated C.sub.6 isomers), and n-heptane at reflux
conditions. Other compatible solvents may be used.
[0045] The polymers of this invention also typically exhibit very
narrow composition distribution within fractions separated by
molecular weight through a supercritical propane fractionation
procedure. As described by McHugh and Krukonis, "Supercritical
Fluid Extraction: Principles and Practice," 2d ed.,
Butterworth-Heinemann, 1994, incorporated by reference herein,
solubility of a polymer in a fluid, such as propane, at
supercritical conditions, is a function of pressure. Thus,
supercritical fluid fractionation may be used to separate fractions
of linear low density polyethylenes according to molecular weight
and degree of short chain branching. Fractions of an inventive
copolymer of differing molecular weights using a supercritical
fluid, such as liquid propane, typically show a narrow composition
distribution of less than 5%, preferably less than about 3%.
[0046] Particularly preferred, current best mode embodiments of the
copolymers of the present invention have the following
characteristics:
[0047] (a) a mole fraction of crystallizable component X.sub.c from
30-99%;
[0048] (b) a typical molecular weight distribution
M.sub.w/M.sub.n>2; and
[0049] (c) melting points above about 90.degree. C.; and
[0050] which copolymers comprise from 0-70% by weight of an ether
soluble fraction, from 0-95% of a hexanes soluble fraction which
can exhibit a melting range up to about 125.degree. C., and from
0-95% of a hexanes insoluble fraction which can exhibit a melting
range up to about 142.degree. C.
[0051] The copolymers of the present invention in one preferred
embodiment can be characterized as reactor blends in that they can
be fractionated into fractions of differing degrees of
crystallinity and differing melting points. Nevertheless, the
comonomer composition of the various fractions of the copolymers
are all within 15% of the composition of the resultant polymer
product produced in the reactor.
[0052] The melting points of the copolymers of the present
invention are high, typically above 90.degree. C. and the melting
point indices, T.sub.m/X.sub.c are also high, typically above
80.degree. C. and preferably above 115.degree. C. The individual
fractions can also exhibit high melting point indices. For example,
it is possible to isolate a hexanes soluble fraction from the
copolymers of the present invention that exhibits a melting point
as high as 115.degree. C. and a melting point index as high as
160.degree. C. The glass transition temperatures (T.sub.g) of the
copolymers are low, typically less than -20.degree. C. and
preferably below -50.degree. C.
[0053] The molecular weights of the polymers of the present
invention can be quite high, with weight average molecular weights
in excess of M.sub.w=1,000,000 readily obtained and molecular
weights as high as 2,000,000 observed. The molecular weight of the
polymer product can be controlled, optionally, by controlling the
temperature or by adding any number of chain transfer agents such
as hydrogen or metal alkyls, as is well known in the art.
[0054] While not wishing to be bound by theory, it is believed that
in the process of the invention, different active species of the
fluxional catalyst are in equilibrium during the construction of
the copolymer chains. This is provided for in the present invention
by a class of unbridged metallocenes that are capable of
isomerizing between states that have different copolymerization
characteristics during the polymerization process, i.e. each state
having a different relative rate of insertion of a given ethylene
or C.sub.4+ monomer into the growing copolymer chain and
preferential selectivity for different monomers under particular
reaction conditions. The process of the invention thus leads to
multiblock copolymers or copolymer blends wherein the blocks or
components of the blends have different compositions of
comonomers.
[0055] The catalysts used in the present invention comprise
unbridged, non-rigid (fluxional) metallocenes which can change
their geometry with a rate that is within several orders of
magnitude of the rate of formation of a single polymer chain, on
average. In accordance with the invention, the relative rates of
interconversion and of formation can be controlled by selecting the
substituents (or absence thereof) on the cyclopentadienyl ligands
so that they can alternate in structure between states of different
coordination geometries which have different selectivity toward a
particular comonomer.
[0056] One embodiment of the invention includes metallocene
catalysts which are able to interconvert between states whose
coordination geometries are different. Thus, the invention includes
selecting the substituents of the metallocene cyclopentadienyl
ligands so that the rate of interconversion of the two states is
within several orders of magnitude of the rate of formation of a
single polymer chain. That is, if the rate of interconversion
between states of the catalyst, r.sub.i, is greater than the rate
of formation of an individual polymer chain, r.sub.f, on average,
the polymer resulting from use of the inventive process and
catalysts can be characterized as multiblock (as defined above). If
the rate of interconversion is less than the rate of formation, the
result is a polymer blend. Where the rates are substantially
balanced, the polymer can be characterized as a mixture of blend
and multiblock. There may be a wide range of variations and
intermediate cases amongst these three exemplars.
[0057] The nature of the substituents on the cyclopentadienyl
ligands is critical; the substitution pattern of the
cyclopentadienyl ligands should be such that the coordination
geometries are different in order to provide different reactivities
toward ethylene and other alpha olefins while in the two (or more)
states (see FIG. 1), and that the rate of interconversion of the
states of the catalyst are within several orders of magnitude of
the rate of formation of a single chain. While not wishing to be
bound by theory, it is currently believed that sterically demanding
cyclopentadienyl substitients, such as a 3,5-disubstituted aryl
group, provide optimized rates of interconversion between the two
states.
[0058] A further embodiment includes metallocene catalysts which
are able to interconvert between more than two states whose
coordination geometries are different. This is provided for by
metallocenes with cyclopentadienyl-type ligands substituted in such
a way that more than two stable states of the catalyst have
coordination geometries that are different. For example, one
embodiment of a catalyst with four geometries is illustrated in
FIG. 2.
[0059] According to the process of this invention, the properties
of the copolymers can be controlled by changing one or more of: the
nature of the cyclopentadienyl units on the catalysts; the nature
of the metal atom in the catalyst; and by changing the process
conditions: e.g., by changing the nature of the comonomers; the
comonomer feed ratio; the temperature; by presence of hydrogen;
and/or control of other conventional process conditions.
[0060] Catalyst systems useful to produce copolymer of the present
invention typically contain a transition metal component
metallocene in the presence of an appropriate cocatalyst. In broad
aspect, the transition metal compounds have the formula: 1
[0061] in which M is a Group 3, 4 or 5 Transition metal, a
Lanthanide or an Actinide, X and X' are the same or different
uninegative ligands, such as but not limited to hydride, halogen,
hydrocarbyl, halohydrocarbyl, amine, amide, or borohydride
substituents (preferably halogen, alkoxide, or C.sub.1 to C.sub.7
hydrocarbyl), and L and L' are the same or different polynuclear
hydrocarbyl, silahydrocarbyl, phosphahydrocarbyl, azahydrocarbyl,
arseni-hydrocarbyl or borahydrocarbyl rings, typically a
substituted cyclopentadienyl ring or heterocyclopentadienyl ring,
in combination with an appropriate cocatalyst. Exemplary preferred
Transition Metals include titanium, vanadium, and, more preferably,
zirconium or hafnium. An exemplary Group 3 metal is yttrium, a
Lanthanide is samarium, and an Actinide is thorium.
[0062] Preferably L and L' have the formula: 2
[0063] where R.sub.1, R.sub.2, R.sub.3, R.sub.9, and R.sub.10 may
be the same or different hydrogen, alkyl, alkylsilyl, aryl,
alkoxyalkyl, alkoxyaryl, alkoxysilyl, aminoalkyl, aminoaryl or
substituted alkyl, alkylsilyl or aryl substituents of 1 to about 30
carbon atoms.
[0064] Ligands of this general structure include substituted
cyclopentadienes. Other ligands L and L' of Formula 2 for the
production of ethylene copolymers include substituted
cyclopentadienes of the general formula: 3
[0065] where R.sub.2-R.sub.10 have the same definition as R.sub.1,
R.sub.2, R.sub.3, R.sub.9, and R.sub.10 above.
[0066] Preferred L and L' of Formula 1 include ligands of Formula 2
wherein R.sub.1 is an aryl group, such as a substituted phenyl,
biphenyl, or naphthyl group, and R.sub.2 and R.sub.3 are connected
as part of a ring of three or more carbon atoms. Especially
preferred for L or L' of Formulas 1-3 for producing the copolymers
of this invention are substituted indenyl ligands, more
particularly 2-arylindene of formula: 4
[0067] where R.sub.4-R.sub.14 may be the same or different
hydrogen, halogen, aryl, hydrocarbyl, silahydrocarbyl, or
halohydrocarbyl substituents. That is, R.sub.1 of Formula 2 is
R.sub.4-R.sub.8-substitute- d benzene, and R.sub.2, R.sub.3 are
cyclized in a 6-carbon ring to form the indene moiety.
[0068] Preferred 2-aryl indenes include ligands in which R.sub.5
and R.sub.7 are substituents other than hydrogen such as aryl,
hydrocarbyl, silahydrocarbyl, alkylsilyl, or halohydrocarbyl
containing up to about 12 carbon atoms. Representative substituents
include C.sub.1-C.sub.6 alkyls (preferably C.sub.3-C.sub.6 branched
alkyls such as isopropyl, isobutyl, s-butyl, t-butyl, isoamyl),
halogenated alkyls, and alkylsilyls, Particularly preferred
substituents are bulky such as t-butyl, trifluoromethyl, and
trimethylsilyl.
[0069] Other preferred ligands contain a non-hydrogen R.sub.9 or
R.sub.10 substituent. Preferred substituents include lower
(C.sub.1-C.sub.6) alkyls such as methyl or ethyl. Typically, a
system containing an R.sub.9 or R.sub.10 substituent will create a
fluxional metallocene catalyst system containing more than two
rotational symmetry states.
[0070] In another preferred aspect of this invention the fluxional
catalyst system contains a metallocene component containing two
different ligands having preselected substituents that provide the
requisite interconverting states as described above.
[0071] 2-Aryl indenes useful to make fluxional metallocene
catalysts in this invention include:
[0072] 2-(3,5-dimethylphenyl) indene;
[0073] 2-(3,5-bis-trifluoromethylphenyl) indene;
[0074] 1-methyl-2-(3,5-bis-trifluoromethylphenyl) indene;
[0075] 2-(3,5-bis-tertbutylphenyl) indene;
[0076] 1-methyl-2-(3,5-bis-tertbutylphenyl) indene;
[0077] 2-(3,5-bis-trimethyl-silylphenyl)indene;
[0078] 1-methyl-2-(3,5-bis-trimethylsilylphenyl)indene;
[0079] 2-(4-fluorophenyl) indene; 2-(2,3,4,5-tetrafluorophenyl)
indene;
[0080] 2-(2,3,4,5,6-pentafluorophenyl) indene;
[0081] 2-(1-naphthyl) indene; 2-(2-naphthyl) indene; and
[0082] 2-[(4-phenyl)phenyl] indene; and 2-[(3-phenyl) phenyl]
indene.
[0083] Typical fluxional metallocenes useful in this invention
include:
[0084] bis[2-(3,5-dimethylphenyl)indenyl] zirconium dichloride;
[0085] bis[2-(3,5-bis-trifluoromethylphenyl)indenyl] zirconium
dichloride;
[0086] bis[2-(3,5-bis-tertbutylphenyl)indenyl] zirconium
dichloride;
[0087] bis[2-(3,5-bis-trimethylsilylphenyl)indenyl] zirconium
dichloride;
[0088] bis[2-(4,-fluorophenyl)indenyl] zirconium dichloride;
[0089] bis[2-(2,3,4,5,-tetrafluorophenyl)indenyl] zirconium
dichloride;
[0090] bis(2-(2,3,4,5,6-pentafluorophenyl)indenyl]) zirconium
dichloride;
[0091] bis[2-(1-naphthyl)indenyl] zirconium dichloride;
[0092] bis(2-(2-naphthyl)indenyl]) zirconium dichloride;
[0093] bis(2-[(4-phenyl)phenyl]indenyl]) zirconium dichloride;
[0094] bis[2-[(3-phenyl)phenyl]indenyl] zirconium dichloride;
[0095] (pentamethylcyclopentadienyl)(1-methyl-2-phenylindenyl)
zirconium dichloride;
[0096] (pentamethylcyclopentadienyl)(2-phenylindenyl) zirconium
dichloride;
[0097] (pentamethylcyclopentadienyl)(1-methyl-2-phenylindenyl)
zirconium dimethyl;
[0098] (pentamethylcyclopentadienyl)(2-phenylindenyl) zirconium
dimethyl;
[0099] (cyclopentadienyl)(1-methyl-2-phenylindenyl) zirconium
dichloride;
[0100] (cyclopentadienyl)(2-phenylindenyl) zirconium
dichloride;
[0101] (cyclopentadienyl)(1-methyl-2-phenylindenyl) zirconium
dimethyl;
[0102] (cyclopentadienyl)(2-phenylindenyl) zirconium dimethyl;
[0103] (1-methyl-2-phenylindenyl)(2-phenylindenyl) zirconium
dichloride;
[0104]
(1-methyl-2-phenylindenyl)[2-(3,5-bis-trifluoromethylphenyl)indenyl-
] zirconium dichloride;
[0105]
[1-methyl-2-(3,5-bis-trifluoromethylphenyl)indenyl](2-phenylindenyl-
) zirconium dichloride;
[0106]
[1-methyl-2-(3,5-bis-trifluoromethylphenyl)indenyl][2-(3,5-bis-trif-
luoromethylphenyl)indenyl] zirconium dichloride; and
[0107]
(1-methyl-2-phenylindenyl)[2-(3,5-bis-tertbutylphenyl)indenyl]
zirconium dichloride;
[0108] Typical fluxional metallocenes useful in this invention also
include the corresponding hafnium compounds such as:
[0109] bis[2-(3,5-dimethylphenyl)indenyl] hafnium dichloride;
[0110] bis[2-(3,5-bis-trifluoromethylphenyl)indenyl] hafnium
dichloride;
[0111] bis[2-(3,5-bis-tertbutylphenyl)indenyl] hafnium
dichloride;
[0112] bis[2-(3,5-bis-trimethylsilylphenyl) indenyl] hafnium
dichloride;
[0113] bis[2,(4-fluorophenyl)indenyl] hafnium dichloride;
[0114] bis[2-(2,3,4,5-tetrafluorophenyl)indenyl] hafnium
dichloride;
[0115] bis[2-(2,3,4,5,6-pentafluorophenyl)indenyl] hafnium
dichloride;
[0116] bis[2-(1-naphthyl)indenyl] hafnium dichloride;
[0117] bis[2-(2-naphthyl)indenyl] hafnium dichloride;
[0118] bis(2-((4-phenyl)phenyl)indenyl]) hafnium dichloride;
[0119] bis[2-[(3-phenyl)phenyl]indenyl] hafnium dichloride;
[0120] (pentamethylcyclopentadienyl)(1-methyl-2-phenylindenyl)
hafnium dichloride;
[0121] (pentamethylcyclopentadienyl)(2-phenylindenyl) hafnium
dichloride;
[0122] (pentamethylcyclopentadienyl)(1-methyl-2-phenylindenyl)
hafnium dimethyl;
[0123] (pentamethylcyclopentadienyl)(2-phenylindenyl) hafnium
dimethyl;
[0124] (cyclopentadienyl)(1-methyl-2-phenylindenyl) hafnium
dichloride;
[0125] (cyclopentadienyl)(2-phenylindenyl) hafnium dichloride;
[0126] (cyclopentadienyl)(1-methyl-2-phenylindenyl) hafnium
dimethyl;
[0127] (cyclopentadienyl)(2-phenylindenyl) hafnium dimethyl;
[0128] (1-methyl-2-phenylindenyl)(2-phenylindenyl) hafnium
dichloride;
[0129]
(1-methyl-2-phenylindenyl)[2-(3,5-bis-trifluoromethylphenyl)indenyl-
] hafnium dichloride;
[0130]
[1-methyl-2-(3,5-bis-trifluoromethylphenyl)indenyl](2-phenylindenyl-
) hafnium dichloride;
[0131] [1-methyl-2-(3,5-bis-trifluoromethylphenyl)indenyl]
[2-(3,5-bis-trifluoromethylphenyl)indenyl] hafnium dichloride;
[0132]
(1-methyl-2-phenylindenyl)[2-(3,5-bis-tertbutylphenyl)indenyl]
hafnium dichloride;
[0133] and the like.
[0134] Particularly preferred metallocene components include:
[0135] bis[2-(3,5-bis-trifluoromethylphenyl)indenyl] hafnium
dichloride;
[0136] bis[2-(3,5-bis-tertbutylphenyl)indenyl] hafnium
dichloride;
[0137] bis[2-(3,5-bis-trimethylsilylphenyl) indenyl] hafnium
dichloride;
[0138]
[1-methyl-2-(3,5-bis-trifluoromethylphenyl)indenyl](2-phenylindenyl-
) zirconium dichloride;
[0139]
[1-methyl-2-(3,5-bis-trifluoromethylphenyl)indenyl][2-(3,5-bis-trif-
luoromethylphenyl)indenyl] zirconium dichloride;
[0140] bis[2-(3,5-bis-trifluoromethylphenyl)indenyl] hafnium
dichloride;
[0141] bis[2-(3,5-bis-tertbutylphenyl)indenyl] hafnium
dichloride;
[0142] bis[2-(3,5-bis-trimethylsilylphenyl) indenyl] hafnium
dichloride;
[0143]
[1-methyl-2-(3,5-bis-trifluoromethylphenyl)indenyl](2-phenylindenyl-
) hafnium dichloride; and
[0144]
[1-methyl-2-(3,5-bis-trifluoromethylphenyl)indenyl][2-(3,5-bis-trif-
luoromethylphenyl)indenyl] hafnium dichloride.
[0145] The Examples disclose a method for preparing the
metallocenes in high yield. Generally, metallocenes are prepared by
forming the indenyl ligand followed by metallation with the metal
tetrahalide to form the complex in synthetic procedures known to
the art.
[0146] Appropriate cocatalysts include alkylaluminum compounds,
methylaluminoxane, or modified methylaluminoxanes, as illustrated
in U.S. Pat. No. 4,542,199 to Kaminsky, et al.; Ewen, J. Am. Chem.
Soc., 106 (1984), p. 6355; Ewen, et al., J. Am. Chem. Soc. 109
(1987) p. 6544; Ewen, et al., J. Am. Chem. Soc. 110 (1988), p.
6255; Kaminsky, et al, Angew. Chem., Int. Ed. Eng. 24 (1985), p.
507. Other useful cocatalysts include Lewis or protic acids, such
as B(C.sub.6F.sub.5).sub.3 or
(PhNMe.sub.2H).sup.+B(C.sub.6F.sub.5).sub.4.sup.-, which generate
cationic metallocenes with compatible non-coordinating anions in
the presence or absence of alkyl-aluminum compounds. Catalyst
systems employing a cationic Group 4 metallocene and compatible
non-coordinating anions are described in U.S. Pat. Nos. 5,198,119,
5,198,401, and 5,223,467; Marks, et al., J. Am. Chem. Soc., 113
(1991), p. 3623; Chien, et al., J. Am. Chem. Soc., 113 (1991), p.
8570; Bochmann et al., Angew. Chem. Intl., Ed. Engl. 7 (1990), p.
780; and Teuben et al., Organometallics, 11 (1992), p. 362, and
references therein; all incorporated by reference herein.
[0147] In one of many embodiments, these catalyst systems may be
placed on a suitable support such as silica, alumina, or other
metal oxides, magnesium halide such as MgCl.sub.2 or other
supports. These catalysts can be used in the solution phase, in
slurry phase, in the gas phase, or in bulk monomer. Both batch and
continuous polymerizations can be carried out. Appropriate solvents
for solution polymerization include liquefied monomer, and
aliphatic or aromatic solvents such as toluene, benzene, hexane,
heptane, diethyl ether, as well as halogenated aliphatic or
aromatic solvents such as methylene chloride, chlorobenzene,
fluorobenzene, hexaflourobenzene or other suitable solvents. Use of
liquid hydrocarbon is preferred, such as hexane or heptane, to
avoid halogenated waste streams. Various agents can be added to
control the molecular weight, including hydrogen, silanes and metal
alkyls such as diethylzinc.
[0148] The copolymers of this invention are prepared by contacting
ethylene and at least one co-monomer with the above-described
catalyst system under suitable polymerization conditions. Such
conditions include polymerization or copolymerization temperature
and time, pressure(s) of the monomer(s), avoidance of contamination
of catalyst, choice of polymerization or copolymerization medium in
slurry processes, the use of additives to control homopolymer or
copolymer molecular weights, and other conditions well known to
persons skilled in the art.
[0149] Typically, sufficient amounts of catalyst or catalyst
component is used for the reactor system and process conditions
selected. The amount of catalyst will depend upon the activity of
the specific catalyst chosen.
[0150] Irrespective of the polymerization or copolymerization
process employed, polymerization or copolymerization should be
carried out at temperatures sufficiently high to ensure reasonable
polymerization or copolymerization rates and avoid unduly long
reactor residence times, but not so high as to cause catalyst
deactivation or polymer degradation. Generally, temperatures range
from about 0.degree. C. to about 120.degree. C. with a range of
from about 20.degree. C. to about 95.degree. C. being preferred
from the standpoint of attaining good catalyst performance and high
production rates. A preferable polymerization range according to
this invention is about 50.degree. C. to about 80.degree. C.
[0151] Olefin polymerization or copolymerization according to this
invention is carried out at monomer pressures of about atmospheric
or above. Generally, monomer pressures range from about 20 to about
600 psi (140 to 4100 kPa), although in vapor phase polymerizations
or copolymerizations, monomer pressures should not be below the
vapor pressure at the polymerization or copolymerization
temperature of the alpha-olefin to be polymerized or
copolymerized.
[0152] The polymerization or copolymerization time will generally
range from about 1/2 to several hours in batch processes with
corresponding average residence times in continuous processes.
Polymerization or copolymerization times ranging from about 1 to
about 4 hours are typical in autoclave-type reactions. In slurry
processes, the polymerization or copolymerization time can be
regulated as desired. Polymerization or copolymerization times
ranging from about 1/2 to several hours are generally sufficient in
continuous slurry processes.
[0153] Examples of gas-phase polymerization or copolymerization
processes in which the catalyst or catalyst component of this
invention is useful include both stirred bed reactors and fluidized
bed reactor systems and are described in U.S. Pat. Nos.3,957,448;
3,965,083; 3,971,786; 3,970,611; 4,129,701; 4,101,289; 3,652,527;
and 4,003,712, all incorporated by reference herein. Typical
gas-phase olefin polymerization or copolymerization reactor systems
comprise at least one reactor vessel to which olefin monomer and
catalyst components can be added and which contain an agitated bed
of forming polymer particles. Typically, catalyst components are
added together or separately through one or more valve-controlled
ports in the single or first reactor vessel. Olefin monomer,
typically, is provided to the reactor through a recycle gas system
in which unreacted monomer removed as off-gas and fresh feed
monomer are mixed and injected into the reactor vessel. A quench
liquid, which can be liquid monomer, can be added to polymerizing
or copolymerizing olefin through the recycle gas system in order to
control temperature.
[0154] Irrespective of polymerization or copolymerization
technique, polymerization or copolymerization is carried out under
conditions that exclude oxygen, water, and other materials that act
as catalyst poisons. Also, according to this invention,
polymerization or copolymerization can be carried out in the
presence of additives to control polymer or copolymer molecular
weights. Hydrogen typically is employed for this purpose in a
manner well known to persons of skill in the art. Although not
usually required, upon completion of polymerization or
copolymerization, or when it is desired to moderate or terminate
polymerization or copolymerization or at least temporarily
deactivate the catalyst or catalyst component of this invention,
the catalyst can be contacted with water, alcohols, carbon dioxide,
oxygen, acetone, or other suitable catalyst deactivators in a
manner known to persons of skill in the art.
[0155] The polymerization of olefins according to this invention is
carried out by contacting the olefin(s) with the catalyst systems
comprising the transition metal fluxional component and in the
presence of an appropriate cocatalyst, such as an aluminoxane, a
Lewis acid such as B(C.sub.6F.sub.5).sub.3, or a protic acid in the
presence of a non-coordinating counterion such as
B(C.sub.6F.sub.5).sub.4.sup.-.
[0156] The metallocene catalyst systems of the present invention
are particularly useful for the polymerization of ethylene and
C.sub.4+ alpha-olefin co-monomers as well as alpha-olefin monomer
mixtures to produce co-polymers with novel thermoplastic,
plastomeric and elastomeric properties. The properties of
elastomers are characterized by several variables. The tensile set
(TS) is the elongation remaining in a polymer sample after it is
stretched to an arbitrary elongation (e.g. 100% or 300%) and
allowed to recover. Lower set indicates higher elongational
recovery. Stress relaxation is measured as the decrease in stress
(or force) during a time period (e.g. 30 sec. or 5 min.) that the
specimen is held at extension. There are various methods for
reporting hysteresis during repeated extensions. In the present
application, retained force is measured as the ratio of stress at
50% elongation during the second cycle recovery to the initial
stress at 100% elongation during the same cycle. Higher values of
retained force and lower values of stress relaxation indicate
stronger recovery force. Better general elastomeric recovery
properties are indicated by low set, high retained force and low
stress relaxation.
[0157] The metallocene catalysts of the present invention are
represented in one embodiment in FIG. 1 where the ligands L and L'
are substituted cyclopentadienyl rings. As shown in the Figure, in
state A cyclopentadienyl substituents R.sub.1, R.sub.2 and R.sub.6
and R.sub.7 project over the ligands X=X' whereas in state B,
cyclopentadienyl substituents R.sub.1, R.sub.2 and R.sub.8 and
R.sub.9 project over the ligands X=X'. As provided for in the
process of this invention, catalysts derived from these
metallocenes where substituents R.sub.6 and R.sub.7 are different
from R.sub.8 and R.sub.9 will exhibit reactivity ratios for
ethylene in state A (r.sub.EA) different from that in state B
(r.sub.EB).
[0158] In another embodiment of the invention, fluxional
metallocene catalysts incorporating hafnium may exhibit increased
reactivity to the higher olefin copolymer (such as hexene, r.sub.H)
relative to the polymerization reactivity to ethylene
(r.sub.E).
[0159] Another embodiment of the invention is illustrated in FIG. 2
where the ligands L and L' are different substituted 2-arylindenyl
ligands such that the metallocene interconverts between four states
with different coordination geometries. As shown in FIG. 3, in two
states a methyl group projects over the coordination sites for
olefin insertion (represented in this figure by circles) and in two
states the methyl group projects away from the coordination sites
for the olefin.
[0160] The following Examples and Comparative Runs illustrate, but
do not limit the inventions described herein.
EXAMPLES
[0161] All organometallic reactions were conducted using standard
Schlenk and drybox techniques. Elemental analyses were conducted by
E+R Microanalytical Laboratory. Unless otherwise specified all
reagents were purchased from commercial suppliers and used without
further purification. 2-Phenylindene, 1-methyl-2-phenylindene,
2-(bis(3',5'-trifluoromethyl) phenylindene,
bis(2-phenylindenyl)zirconium dichloride, rac- and
meso-bis(1-methyl-2-phenylindenyl)zirconium dichloride,
ethylene-bis(indenyl)zirconium dichloride, and
bis(2-(bis(3',5'-trifluoromethyl)phenylindenyl)-zirconium
dichloride were prepared according to the literature procedures
(Kravchenko, R.; Waymouth, R. M. Macromolecules 1998, 31, 1-6.)
Hexane, pentane and methylene chloride used in organometallic
synthesis were distilled from calcium hydride under nitrogen.
Tetrahydrofuran was distilled from sodium/benzophenone under
nitrogen. Toluene, ethylene and propylene were passed through two
purification columns packed with activated alumina and supported
copper catalyst. 1-Hexene and chloroform-d.sub.3 were distilled
from calcium hydride and benzene-d.sub.6 was distilled from
sodium/benzophenone.
Metallocenes 1-3
[0162] Ethylene-bis(indenyl)zirconium dichloride (Metallocene 1):
This complex was prepared as described in Wild, F. R. W. P.;
Wasiucionek, M.; Huttner, G.; Brintzinger, H. H. J. Organomet.
Chem. 1985, 288, 63-7.
[0163] Bis(2-phenylindenyl)zirconium dichloride (Metallocene 2):
This complex was prepared as described in Bruce, M. D.; Coates, G.
W.; Hauptman, E.; Waymouth, R. M.; Ziller, J. W. J. Am. Chem. Soc.
1997, 119, 11174-11182.
[0164] Bis(2-phenylindenyl)hafnium dichloride (Metallocene 3): This
complex was prepared as described in Bruce, M. D.; Coates, G. W.;
Hauptman, E.; Waymouth, R. M.; Ziller, J. W. J. Am. Chem. Soc.
1997, 119, 11174-11182.
Ligand A: 2-(Bis-3,5-trifluoromethylphenyl)indene
[0165] A 3-neck 500 mL round-bottomed flask fitted with a condenser
and an addition funnel was charged with 2.62 g (0.11 mol) of Mg
turnings and 20 mL of anhydrous diethyl ether. Slow addition of a
solution of 25.10 g (0.09 mol) of 3,5-bis(trifluoromethyl)
bromobenzene in diethyl ether (100 mL), followed by refluxing for
30 min, gave a brown-gray solution of the aryl Grignard reagent.
The solution was cooled to room temperature (RT), filtered over a
plug of Celite and evacuated to yield a brown oil. Toluene (40 mL)
was added and the suspension cooled to 0.degree. C. whereupon a
solution of 2-indanone (9.22 g, 0.07 mol) in toluene (60 mL) was
added dropwise to give a tan-brown slurry. This mixture was warmed
to room temperature and stirred for an additional 3 hours. After
cooling to 0.degree. C. it was quenched with 150 mL of water,
hexane (200 mL) added and the reaction mixture neutralized with 5M
HCl. The organic layer was separated, and the aqueous layer was
extracted with two 50-mL portions of hexane. The combined organic
layers were washed with two 50-mL portions of brine and dried over
anhydrous magnesium sulfate. After filtration over Celite, the
solvent was removed under vacuo yielding 21.5 g (89% based on
2-indanone) of 2-(bis-3,5-trifluoromethylphenyl) indanol as an
off-white solid. .sup.1H NMR (CDCl.sub.3, 23 C., 400 MHz):
.delta.8.05 (s, 2H), 7.80 (s, 1H), 7.5-7.0 (M, 4H), 3.41 (m, 4H),
2.21 (s, 1H, OH). Under argon, this alcohol (21.5 g, 0.06 mol) and
p-toluene-sulfonic acid monohydrate (800 mg) were dissolved in
toluene (250 mL) and the solution was heated to reflux for 6 hours
to afford 14.4 g, (70%) of 2-(bis-3,5(trifluoromethyl)-phenyl)
indene upon recrystallization from diethyl ether/hexane at
-18.degree. C. .sup.1H NMR (CDCl.sub.3, 23.degree. C., 400 MHz):
.delta.8.01 (s, 2H, Ar.sub.f), 7.75 (s, 1H, Ar.sub.f), 7.52 (d, J=7
Hz, 1H), 7.47 (d, J=7 Hz, 1H), 7.43 (s, 1H), 7.33 (dd, 2J=7 Hz,
1H), 7.27 (dd, 2J=7 Hz, 1H), 2.83 (s, 2H). .sup.13C NMR
(CDCl.sub.3, 23 C., 100 MHz): .delta.144.3 (s), 143.1 (s), 138.0
(s), 132.1 (q, .sup.2J.sub.C-F=33 Hz), 130.1 (d, J.sub.C-H=167 Hz),
127.0 (dd), J.sub.C-H=160 Hz, .sup.2J.sub.C-H=7 Hz), 126.0 (dd,
J.sub.C-H=159 Hz, .sup.2J.sub.C-H=7 Hz), 125.2 (brd, J.sub.C-H=162
Hz), 123.9 (dd, J.sub.C-H=156 Hz, .sup.2J.sub.C-H=9 Hz), 123.4 (q,
J.sub.C-F=273 Hz, CF.sub.3), 121.8(dd, J.sub.C-H=160 Hz,
.sup.2J.sub.C-H=8 Hz), 120.6 (brd, J.sub.C-H=167 Hz), 38.9 (td,
J.sub.C-H=127 Hz, .sup.2J.sub.C-H=7 Hz, CH.sub.2). C,H analysis:
Anal. Found (Calcd): C, 62.45 (62-20); H 3.01 (3.07).
Metallocene 4: Bis(2-(3,5-trifluoromethylphenyl)indenyl) zirconium
dichloride
[0166] N-Butyllithium (2.5 M in hexanes, 0.850 mL, 2.13 mmol) was
added to a solution of 2-(bis-3,5trifluoromethylphenyl) indene
(Ligand A) (648 mg, 1.97 mmol) in toluene (15 mL). The
heterogeneous solution was stirred at ambient temperature for 4
hours 30 minutes to give a green-yellow solution which was treated
with a suspension of ZrCl.sub.4 (240 mg, 1.03 mmol) in toluene (20
mL) via cannula. The yellow suspension was stirred at room
temperature for 2.5 hours, heated to ca. 80.degree. C., and
filtered over a plug of Celite. After washing the Celite with hot
toluene several times (3.times.10 mL), the filtrate was
concentrated and cooled to -18 C. to give 442 mg (55%) of light
yellow crystals of Bis(2-(Bis-3,5-trifluoromethylphenyl)-indenyl
zirconium dichloride. .sup.1H NMR (C.sub.6D.sub.6, 23.degree. C.,
400 MHz): .delta.7.67 (s, 2H, Ar.sub.f), 7.55 (s, 4H, Ar.sub.f),
7.19 (m, 4H, Ar), 6.89 (m, 4H, Ar), 5.96 (s, 4H, Cp-H). .sup.13C
NMR (C.sub.6D.sub.6, 23 C., 100 MHz: .delta.135.6 (s), 133.1 (s),
131.6 (q, .sup.2J.sub.C-F=33 Hz), 127.1 (brd, J.sub.C-H=161 Hz),
126.8 (s), 126.4 (dd, J.sub.C-H=161 Hz, .sup.2J.sub.C-H=8 Hz),
125.4 (dd, J.sub.C-H=167 Hz), .sup.2J.sub.C-H=5 Hz), 123.8 (q,
J.sub.C-F=273 Hz, C-F), 121.8 (brd, J.sub.C-H=159 Hz), 102.5 (dd,
J.sub.C-H=176 Hz, .sup.2J.sub.C-H=7 Hz, Cp (C-H). C,H analysis:
Anal. found (Calcd.): C, 49.99 (50.01); H 2.32 (2.22).
Metallocene 5: Bis(2-(3,5-trifluoromethylphenyl)indenyl) hafnium
dichloride
[0167] N-Butyllithium (1 .6M in hexanes, 2 mL. 3.20 mmol) was added
dropwise at room temperature to a solution of
2-(bis-3,5-trifluoromethylp- henyl)indene (1.03 g. 3.14 mmol) in
diethyl ether (10 mL). After stirring for 30 min, the solvent was
removed in vacuo leaving a green-yellow solid. In a drybox,
HfCl.sub.4, (510 mg, 1.59 mmol) was added to the lithium salt. The
solids were then cooled to -78.degree. C. at which temperature
toluene (45 mL) was slowly added. The flask was allowed to reach
ambient temperature and the suspension was stirred for 24 hours
after which time it was heated for 15 min to ca. 80.degree. C.
(heat gun). The solvent was then removed in vacuo. The solid was
extracted with CH.sub.2Cl.sub.2 (50 mL) and the solution filtered
over a plug of Celite. After washing the Celite with 4.times.15 mL
CH.sub.2Cl.sub.2, the solvent was removed in vacuo from the
filtrate. The solid was dissolved in 15 mL of CH.sub.2Cl.sub.2,
filtered and over filtrate a layer of hexane (40 mL) was slowly
added. Crystals of Bis(2-(bis-3,5trifluoromethylphenyl)indenyl- )
hafnium dichloride Catalyst E were obtained from this layered
solution at -18.degree. C. .sup.1H NMR (C.sub.6D.sub.6, 23.degree.
C., 200 MHz); .delta.7.65 (s, 2H, Ar.sub.f), 7.51 (s, 4H,
Ar.sub.f), 6.7-7.3 (m, 8H Ar), 5.63 (s, 4H, Cp-H). .sup.13C NMR
(C.sub.6D.sub.6 23.degree. C., 100 MHz): .delta.135.8 (s), 132.9
(s), 131.6 (q, .sup.2J.sub.C-F=34 Hz), 127.2 (brd, J.sub.C-H=160
Hz), 126.3 (dd, J.sub.C-H=161 Hz, .sup.2 J.sub.C-H=8 Hz), 126.0
(s), 125.6 (dd, J.sub.C-H=167 Hz, .sup.2J.sub.C-H=5 Hz), 123.8 (q,
J.sub.C-F=273 Hz, CF.sub.3), 121.7 (brd, J.sub.C-H=161 Hz), 100.1
(dd, J.sub.C-H=176 Hz, .sup.2J.sub.C-H=6 Hz, Cp C-H). C, H
analysis: Anal. Found (Calcd.): C, 45.10 (45-18); H, 1.87
(2.01).
Ligands B-C: 1-Methyl -2-(bis-3',5'-trifluoromethylphenyl)indene
(Ligand B), and 3-methyl-2-(bis-3',5'-trifluoromethylphenyl)indene
(Ligand C)
[0168] A solution of 2-(bis-3',5'-trifluoromethylphenyl)indene
(Ligand A) (1.819 g, 5.54 mmol) in tetrahydrofuran (30 mL) was
cooled to -78.degree. C. and n-butyllithium (2.5 M in hexanes, 2.33
mL, 5.82 mmol) was added dropwise. The resulting orange-brown
solution was allowed to warm to room temperature and stirred for an
additional 30 min. Then CH.sub.3l (1.20 mL, 19 mmol) was added to
this solution and the greenish reaction mixture was stirred for 20
h at room temperature. Methanol (20 mL) was added and the solvents
removed in vacuo. The resulting brown solid was extracted with
toluene (30 mL) and filtered through a glass frit packed with
Celite. The brown solution was washed with H.sub.2O (2.times.10 mL)
and saturated NaCl solution (2.times.10 mL), dried over MgSO.sub.4,
and then evaporated to dryness. Crystallization from hexanes gave
yellow crystals of Ligand B (1.073 g). .sup.1H NMR (20.degree. C.,
CDCl.sub.3, 400 MHz): .delta.7.87 (s, 2H), 7.75 (s, 1H), 7.49 (d,
1H, J=7.3 Hz), 7.42 (d, 1H, J=7.6 Hz), 7.37 (t, 1H, J=7.3 Hz), 7.26
(td, 1H, J=7.3 Hz, J=1.2 Hz), 3.78 (s, 2H), 2.33 (s, 3H). Anal.
Calcd (Found) for C.sub.18H.sub.12F.sub.6: C, 63.16 (63.12); H 3.53
(3.62). Repeated crystallization from hexanes gave a mixture of
isomers of Ligands B and C (309 mg) in 4:1 ratio. .sup.1 H NMR:
3.14 (q, 1H, J=7.0 Hz), 0.87 (d, 3 H, J=7.1 Hz). Overall yield
1.073 g, 73%.
(2-Phenylindenyl) zirconium trichloride
[0169] Solid Zr(NMe.sub.2).sub.4 (1.280 g, 4.785 mmol) and
2-phenylindene (0.920 g, 4.785 mmol) were combined with toluene (30
mL) in a 100-mL Schlenk tube and the resulting pale yellow solution
was stirred for 2.5 h at room temperature under slightly reduced
pressure. Then the solution was evaporated to dryness to give a
yellow oil which was extracted with pentane (20 mL) and filtered
through a cannula fitted with a double layer of filter paper. The
resulting pentane solution was concentrated to a total volume of 10
mL and placed into a -50.degree. C. freezer overnight. The
resulting yellow solid was isolated, dried in vacuo, and
redissolved in CH.sub.2Cl.sub.2 (15 mL). The pale yellow solution
was cooled to 0 C. and chlorotrimethylsilane (2 mL, 15.8 mmol) was
added via syringe. The bright yellow solution was allowed to warm
to room temperature and stirred for 1 h. Then the solution was
evaporated to dryness to yield a yellow/orange foamy solid. Toluene
(30 mL) was added and the mixture was stirred for 48 h to yield a
lemon yellow powder, which was isolated and dried in vacuo (1.098
g, 59% yield). This material was used without further
purification.
Metallocene 6: (2-Phenylindenyl)(1-methyl -2-phenylindenyl)
zirconium dichloride
[0170] Butyllithium (2.5 M in hexane, 0.43 mL, 1.08 mmol) was added
via syringe to the solution of 1-methyl-2-phenylindenyl (212 mg,
1.029 mmol) in diethyl ether (25 mL) at -78.degree. C. The
resulting light yellow solution was allowed to warm to room
temperature and stirred for additional 30 min. The ether was
removed in vacuo to yield a white powdery solid, which was combined
with solid (2-phenylindenyl)zirconium trichloride (400 mg, 1.029
mmol) and toluene (50 mL). The resulting suspension was stirred for
24 h at room temperature. Gradually the solids dissolved to give a
yellow turbid solution. The mixture was filtered through a glass
frit packed with Celite and then evaporated to dryness. The
resulting yellow solid was recrystallized from CH.sub.2Cl.sub.2 (10
mL) layered with pentane (30 mL) at -50.degree. C. to give
Metallocene 6, 181 mg, 31% yield. .sup.1 H NMR (20.degree. C.,
C.sub.6D.sub.6, 400 MHz): .delta.7.41 (d, 2H, J=11.2 Hz), 7.30 (d,
2H, J=10.8 Hz), 7.24-6.80 (m, 13H), 6.73 (d, 1H, J=11.2 Hz), 6.50
(d, 1H, J=3.2 Hz), 6.26 (d, 1H, J=3.3 Hz), 5.98 (s, 1H), 2.42 (s,
3H). .sup.13C {.sup.1H} NMR (20.degree. C., CDCl.sub.3, 125 MHz):
.delta.133.75 (C), 133.10 (C), 132.38 (C), 131.41 (C), 129.54 (C),
129.06 (C-H), 128.90 (C-H), 128.70 (C-H), 128.67 (C-H), 128.14
(C-H), 126.95 (C), 126.72 (C-H), 126.58 (C-H), 126.56 (C-H), 126.43
(C-H), 126.26 (C-H), 125.58 (C-H), 125.05 (C), 124.90 (CH), 124.56
(C), 124.35 (C-H), 123.68 (C-H), 121.43 (C), 104.34 (C-H, Cp),
100.70 (C-H, Cp), 99.00 (C-H, Cp), 12.54 (CH3). Anal. Calcd (Found)
for C.sub.31H.sub.24Cl.sub.2Zr: C 66.65 (66.92); H 4.33 (4.36).
Metallocene 7:
(2-Phenylindenyl)(1-methyl-2-(bis-3',5'-trifluoromethylphen- yl)
indenyl) zirconium dichloride
[0171] Butyllithium (2.5 M in hexanes, 0.43 mL, 1.08 mmol) was
added to the pale yellow solution of
1-methyl-2-(bis-3',5'-trifluoromethylphenyl)i- ndene (352 mg, 1.029
mmol) in diethyl ether (20 mL) at -78.degree. C. via syringe. The
resulting yellow solution was allowed to warm to room temperature
and stirred for additional 30 min. Ether was removed in vacuo to
yield a pale yellow solid which was washed with pentane (20 mL) and
combined with solid (2-phenylindenyl)zirconium trichloride (400 mg,
1.029 mmol) and toluene (50 mL). The resulting suspension was
stirred for 24 h at room temperature. Gradually the solids
dissolved to give a yellow turbid solution. This solution was
filtered through a glass frit packed with Celite and then
evaporated to dryness. The yellow solid Metallocene 7 was
recrystallized from CH.sub.2Cl.sub.2 (10 mL) layered with pentane
(20 mL) at -50.degree..degree.C.: (245 mg, 34%) H NMR (20.degree.
C., C.sub.6D.sub.6, 400 MHz): .delta.7.67 (s, br, 1H), 7.64 (s, br,
2H), 7.30-6.78 (m, 13H), 6.43 (d, 1H, J=2.4 Hz), 6.19 (d, 1H, J=2.4
Hz), 5.59 (s, 1H), 5.32 (s, 1/3 H, CH.sub.2Cl.sub.2), 2.24 (s, 3H).
.sup.13C {.sup.1H} NMR (20.degree. C., CDCl.sub.3, 125 MHz):
.delta.135.91 (C-H), 133.59 (C), 132.58 (C), 131.47 (C-CF.sub.3,
.sup.2J.sub.C-F=33 Hz), 130.76 (C), 130.51 (C), 129.02 (C-H),
128.98 (C-H), 128.80 (C-H), 126.87 (C-H), 126.81 (C-H), 126.77
(C-H), 126.62 (C-H), 126.52 (C-H), 126.25 (C-H), 126.21 (C), 125.34
(C-H), 125.05 (C), 124.09 (C-H), 123.86 (C), 123.23 (CF.sub.3,
J.sub.CF=273 Hz), 123.17 (C), 121.24 (C-H, br), 119.25 (C), 102.70
(C-H, Cp), 101.76 (C-H, Cp), 99.30 (C-H, Cp), 12.12 (CH.sub.3).
Anal. Calcd (Found) for C.sub.33H.sub.22Cl.sub.2F.sub.6Zr.tim-
es.1/6.CH.sub.2Cl.sub.2: C 55.86 (56.20); H 3.37 (3.18). After
having been stored for 3-4 weeks in the drybox in a clear vial the
yellow compound turned green in color. No changes in .sup.1H NMR
spectrum were detected upon the color change.
(2-(Bis-3',5'-trifluoromethylphenyl)indenyl) zirconium
trichloride.MeSiN Me.sub.2
[0172] Solid Zr(NMe.sub.2).sub.4 (1.260 g, 4.713 mmol) and
1-methyl-2-(bis-3',5'-trifluoromethylphenyl)indene (1.505 g, 4.58
mmol) were combined with toluene (30 mL) in a 100-mL Schlenk tube
and the resulting greenish-brown solution was stirred for 2.5 h at
room temperature under slightly reduced pressure. Then the solution
was evaporated to dryness to give greenish-brown solid, which was
extracted with pentane (30 mL) and filtered through a cannula
fitted with a double layer of filter paper. The resulting pentane
solution was concentrated to a total volume of 8 mL and placed in a
-50.degree. C. freezer overnight. Greenish-brown crystals formed.
They were isolated, dried in vacuo and redissolved in
CH.sub.2Cl.sub.2 (20 mL).
[0173] The resulting solution was cooled to 0.degree. C. and
chlorotrimethylsilane (2 mL, 15.8 mmol) was added via syringe. The
turbid yellow solution was allowed to warm to room temperature,
stirred for 1 h, concentrated to a total volume of 1 mL and then
diluted with toluene (30 mL). The resulting suspension was stirred
for 24 h. The lemon yellow powdery solid was isolated and dried in
vacuo (1.390 g, 46%) .sup.1H NMR (20.degree. C., CDCl.sub.3, 400
MHz): .delta.8.19-8.17 (br, 1H), 8.10 (br, 2H), 7.99 (br, 1H), 7.83
(br, 1H), 7.77 (br, 1H), 7.61 (br. 2H), 7.53 (appears as poorly
resoled dd, 2 H), 7.44-7.38 (br, 1H), 7.30 (br, 2H), 7.20 (m, 1H),
7.03 (br, 2H), 6.95 (s, 1H), 6.83 (br, 1H), 2.45 (br, 6H), 0.41 (s,
9H). Broad peaks in the aromatic region appear to indicate the
presence of dimerized or oligomerized forms of
(bistrifluoromethylphenyl)ZrCl.sub.3. In addition, one NMe.sub.2
group (2.45 ppm) and one SiMe.sub.3 group (0.41 ppm) per every two
2-bis(3',5'-trifluoromethyl)-phenylindenyl entities appear to be
coordinated to the metal. This material was used without further
purification.
Metallocene 8:
(2-(3',5'-Trifluoromethylphenyl)indenyl)(1-methyl-2-phenyli-
ndenyl) zirconium dichloride
[0174] Butyllithium (2.5 M in hexanes, 0.55 mL, 1.38 mmol) was
added to the solution of 1-methyl-2-phenylindene (277 mg, 1.31
mmol) in diethyl ether (25 mL) at -78.degree. C. via syringe. The
resulting light yellow solution was allowed to warm to room
temperature, stirred for an additional 15 min, and the ether was
removed in vacuo to yield a white powdery solid which was combined
with solid (2-(bis-3',5'-trifluoromethyl- phenyl)indenyl) zirconium
trichloride.Me.sub.3SiNMe.sub.2 (695 mg, 1.31 mmol) and toluene (40
mL) at 0.degree. C. The resulting dark green solution was allowed
to warm to room temperature and stirred for 40 h during which time
the color of the solution gradually turned lemon-yellow. The turbid
solution was filtered through a glass frit packed with Celite and
then evaporated to dryness. Orange crystals were obtained from a
CH.sub.2Cl.sub.2 (5 mL)/pentane (5 mL) solution stored at
-50.degree. C. (200 mg, 28%). .sup.1 H NMR (20.degree. C.,
CDCl.sub.3, 500 MHz): .delta.7.84 (s, 2H, br), 7.82 (s, 1H, br),
7.52 (t, 2H, J=7.5 Hz), 7.43 (m, 3H), 7.36 (m, 2H), 7.29 (m, 2H),
7.20 (t, 1H, J=6.0 Hz), 7.08 (q, 2H, J=7.0 Hz), 6.68 (d, 1H, J=2
Hz), 6.38 (d, 1H, J=2 Hz), 5.99 (s, 1H), 5.32 (s, 1/3 H,
CH.sub.2C.sub.12), 2.53 (s, 3H). .sup.13C {.sup.1H} NMR (20.degree.
C., CDCl.sub.3, 125 MHz): .delta.135.48 (C), 133.20 (C), 132.23
(C), 132.20 (C), 131.62 (C-CF.sub.3, .sup.2J.sub.C-F=34 Hz), 130.23
(C), 129.03 (CH), 128.61 (CH), 128.44 (C-H), 126.87 (C-H), 126.71
(C-H), 126.70 (C-H), 126.54 (C-H), 126.45 (C-H), 126.24 (C-H),
125.90 (C), 125.17 (C-H), 125.01 (C), 124.43 (C), 124.15 (C-H),
124.13 (C-H), 123.22 (CF.sub.3, J.sub.C-F=272 Hz), 121.70 (C-H,
br), 102.09 (C-H, Cp); 101.20 (C-H, Cp), 98.51 (C-H, Cp), 12.39
(CH.sub.3). Anal. Calcd (Found) for
C.sub.33H.sub.22Cl.sub.2F.sub.6Zr.tim- es.1/6.CH.sub.2Cl.sub.2: C
56.20 (56.11); H 3.18 (3.09).
Metallocene 9:
(2-(3',5'-Trifluoromethylphenyl)indenyl)(1-methyl-2-(bis-3'-
,5'-trifiluoromethylphenyl) indenyl) zirconium dichloride
[0175] Butyllithium (2.5 M in hexanes, 0.40 mL, 1.00 mmol) was
added to the solution of 2-(bis-3,5-trifluoromethylphenyl)indene
(Ligand B) (328 mg, 0.958 mmol) in diethyl ether (30 mL) at
-78.degree. C. via syringe. The resulting light yellow solution was
allowed to warm to room temperature, stirred for additional 2.5 h
and the ether was removed in vacuo to yield a gray powdery solid,
which was washed with pentane, filtered, and dried in vacuo. The
solid was then combined with solid (2-(bis-3',5'
-trifluoromethylphenyl)indenyl) zirconium
trichloride.Me.sub.3SiNMe.sub.2 (508 mg, 0.958 mmol) and toluene
(50 mL) and the reaction mixture was stirred for 40 h at room
temperature. The turbid yellow solution was filtered through a
glass frit packed with Celite and then evaporated to dryness. The
resulting solid was extracted with CH.sub.2Cl.sub.2 (10 mL). The
yellow methylene chloride solution was placed in a -50.degree. C.
freezer overnight and a yellow precipitate formed (100 mg, 13%)
.sup.1H NMR (20.degree. C., C.sub.6D.sub.6, 500 MHz): .delta.7.56
(s, 2H, br), 7.48 (s, 2H, br), 7.29 (d, 1H, J=8.5 Hz), 7.08 (m,
2H), 6.90 (m, 2H), 6.83 (t, 2H, J=7.0 Hz), 6.66 (t, 1H, J=7.5 Hz),
6.00 (d, 1H, J=2.5 Hz), 5.73 (d, 1H, J=2.5 Hz), 5.48 (s, 1 H), 2.14
(s, 3H). .sup.19F NMR (20.degree. C., C.sub.6D.sub.6, 282 MHz): d
63.65 (s, 3F), 63.57 (s, 3F). .sup.13C {.sup.1H} NMR (20.degree.
C., CDCl.sub.3, 125 MHz): .delta.135.61 (C), 133.85 (C), 132.66
(C), 131.64 (C-CF.sub.3, .sup.2J.sub.C-F=33 Hz), 131.44
(C-CF.sub.3, .sup.2J.sub.C-F=33 Hz), 130.78 (C), 129.03 (CH),
129.00 (CH), 127.85 (C), 126.79 (CH), 126.63 (CH), 126.57 (CH),
126.35 (CH), 125.91 (CH), 124.95 (CH), 124.74 (C), 124.59 (CH),
124.28 (CH), 123.50 (CF.sub.3, J.sub.C-F=273 Hz), 123.15 (CF.sub.3,
J.sub.C-F=273 Hz), 122.83 (C), 122.09 (C), 121.89 (CH, br), 121.42
(CH, br), 118.74 (C), 103.28 (CH, Cp), 100.28 (CH, Cp), 99.57 (CH,
Cp), 12.17 (CH.sub.3). Anal. Calcd (Found) for
C.sub.35H.sub.20Cl.sub.2F.sub.12Zr: C 50.61 (50.90); H 2.43
(2.72).
Metallocene 10: Bis(2-(bis-3,5-tert-butyl4-methoxyphenyl) indenyl)
zirconium dichloride
[0176] A sample of 5.584 g (40 mmol) potassium carbonate and 6.3 mL
(100 mmol) iodomethane were reacted with 2.554 g (10 mmol)
bis-3,5-teif-butyl-4-hydroxybenzoic acid and heated to 45.degree.
C. for 30 h. Flash chromatography of the crude product on silica
gel with 7.5% ether in hexanes then recrystallization from hexanes
at -20.degree. C. yielded
methyl-bis-3,5-tert-butyl-4-methoxybenzoate. Yield: 2.213 g (7.95
mmol, 80%). .sup.1H NMR (CDCl.sub.3): d 1.42 (s, 18H), 3.68 (s,
3H), 3.87 (s, 3H), 7.93 (s, 2H); .sup.13C NMR (CDCl.sub.3): d
31.91, 35.86, 51.93, 64.40, 124.35, 128.24, 144.01, 163.84, 167.45.
The methyl ester (8 mmol) was dissolved in 65 mL of THF in an
addition funnel and added to a solution of the di-Grignard of
o-xylylenedichloride solution at -78.degree. C. over approx. 60
minutes, consistently maintaining the temperature below -70.degree.
C. during the addition. The reaction mixture was warmed to
0.degree. C. in 1-2 h and 80 mL distilled water was added through
the addition funnel in 15-30 minutes. After the reaction mixture
was allowed to warm to room temperature the THF was removed
completely from the reaction mixture. The remaining suspension was
acidified to pH=1 and extracted with methylene chloride. The
combined organic layers were dried over magnesium sulfate and
stirred with 0.300 g (1.57 mmol) paratoluenesulfonic acid
monohydrate for 1 h at room temperature. After extraction with
distilled water and drying over magnesium sulfate, the crude indene
product was transferred to silica gel and purified by flash
chromatography. Yield 2.346 g (7.01 mmol, 87%). .sup.1 H NMR
(CD.sub.2Cl.sub.2): .delta.1.47 (s, 18H), 3.71 (s, 3H), 3.79 (s,
2H), 7.14 (s, 1H), 7.15 (td, J 7.0 Hz, J=0.8 Hz), 1H), 7.25 (t,
J=7.5 Hz, 1H), 7.37 (d, J=7.5 Hz, 1H), 7.62 (d, J=7.5 Hz, 1H), 7.54
(s, 2H); .sup.13C NMR (CD.sub.2Cl.sub.2): .delta.32.18, 36.09,
39.47, 64.65, 120.88, 123.89, 124.41,
[0177] 124.68, 125.36, 126.87, 130.67, 143.53, 144.24, 146.05,
147.55, 159.94.
[0178] A sample of 1.5 mmol of the
2-(bis-3,5-tert-butyl-4-methoxyphenyl)i- ndene product was
dissolved in 50 mL of diethylether. The solution was cooled down to
0.degree. C. and 0.6 mL (1.5 mmol) n-butyllithium (2.5 M in
hexanes) was added dropwise via syringe. The cooling bath was
removed and the mixture was stirred at ambient temperature for 10 h
and evacuated to dryness. Zirconium tetrachloride, 175 mg (0.75
mmol), and 100 mL toluene was added and the reaction mixture
stirred vigorously at 25.degree. C. for 3 days. Toluene was removed
in vacuo and 50 mL methylene chloride added. The suspension was
filtered over celite through a Schlenk-frit under argon and washed
with methylene chloride until the filtered liquid remained
colorless. The resulting clear solution's volume was reduced to 1/4
to 1/5 and a layer of pentane, hexanes or diethylether was applied
carefully. The layered solution was stored at -80.degree. C. for
crystallization of the product. Yield: 293 mg (0.353 mmol, 36%),
yellow solid. .sup.1 H NMR (CD.sub.2Cl.sub.2): .delta.1.56 (s,
36H), 3.82 (s, 6H), ), 6.64-6.68 (m, 4H), 6.72 (s, 4H), 6.98-7.01
(m, 4H), 7.63 (s, 4H); .sup.13C NMR CD.sub.2Cl.sub.2):
.delta.32.16, 36.13, 64.67, 104.50, 124.32, 125.48, 126.11, 126.40,
127.03, 129.51, 144.65, 160.45. Anal. Calcd for
C.sub.48H.sub.58Cl.sub.2O.sub.2Zr: C, 69.54; H, 7.05. Found: C,
69.41; H, 7.24.
Metallocenes 1 1 and 12
[0179] Bis(2-(bis-3,5-tert-butylphenyl)indenyl) zirconium
dichloride (Metallocene 11) and
Bis(2-(bis-3,5-trimethylsilyllphenyl)indenyl) zirconium dichloride
(Metallocene 12) were obtained from SRI International.
[0180] General Polymerization Procedures
[0181] Ethylene-Hexene Copolymerization
[0182] A portion of metallocene was dissolved in 25 mL of toluene
in the N.sub.2 dry box. Methylaluminoxane (MAO) (Akzo Type 4
modified MAO) was dissolved in 35 mL of 1-hexene. The MAO solution
was loaded into a 150 mL 2-ended injection tube. Meanwhile, a 300
mL stainless steel Parr reactor was evacuated to 100 mtorr and
refilled with Ar. The reactor was flushed three times with 50 psig
(450 kpa) Ar and then 129 psig (990 kPa) ethylene. The MAO solution
was introduced to the reactor and was allowed to equilibrate with
under the desired head pressure of ethylene for 30 min. 1-Hexene
(3.2 mL) and an aliquot of metallocene stock solution (1.8 mL) was
introduced to a 25 mL 2-ended injection tube. The ethylene feed was
disconnected from the reactor and the pressure was vented by 10 psi
(70 kPa). The metallocene solution was injected under the desired
head pressure of ethylene to start the reaction. The ethylene feed
was immediately reconnected to the reactor. The temperature was
controlled at 18.degree. C. throughout the reaction via an ethylene
glycol/water cooling loop. The reaction was quenched with methanol
injected under Ar pressure after one hour. The reactor was vented
and the copolymer was collected and stirred with acidified methanol
overnight. The copolymer was then rinsed with methanol and dried to
constant weight in a vacuum oven at 40.degree. C.
[0183] Ethylene Homopolymerization
[0184] The homopolymerization procedure was identical to that
employed in copolymerizations. However, hexane was substituted for
1-hexene as the reaction solvent.
[0185] Ethylene-1-Hexene Copolymer Characterization
[0186] Number and weight average molecular weights (M.sub.n and
M.sub.w) were obtained using a Waters 150 C. High Temperature
Chromatograph. Samples were run in 1,2,4-trichlorobenzene at
139.degree. C. using two Polymer Laboratories PL GEL Mixed-B
columns at a flow rate of 1 mL/min. Molecular weights are reported
versus high density polyethylene standards. Viscosities were
measured at 130.degree. C. in tetralin.
[0187] Copolymer composition and monomer sequence distribution were
determined using 13C NMR spectroscopy. Copolymer samples (180-300
mg) were dissolved in 2.5 mL of o-dichlorobenzene/10 vol. %
benzene-d.sub.6 in 10 mm tubes. .sup.13C NMR spectra were recorded
at 75.425 MHz on a Varian UI 300 spectrometer at 100.degree. C.
using 10 mm sample tubes. Samples were prepared in
1,2-dichlorobenzene containing about 0.5 mL d.sub.6-benzene and
approximately 5 mg of chromium(III) acetylacetonate to reduce T1
spin relaxation times. Spectra were acquired using pulse repetition
intervals of 5 s and gated proton decoupling.
[0188] The monomer feed ratio (X.sub.e/X.sub.h) was calculated
using an equation reported in Spitz et al., Eur. Polym. J., 1979,
v.85, pp 441-4 for the solubility of ethylene in 1-hexene.
Determination of copolymer composition (mol % E) and sequence
distribution were carried out using the method of Cheng (Polym.
Bull., 1991, v.26, 325). The triad distributions for commercial
elastomers (ENGAGE.TM. 8200 and EXACT.TM. 4033) were calculated by
methods outlined by Randall (Macromol. Sci. Rev. Macromol. Chem.
Phys., 1989, v.C29, pp 201-317).
[0189] The glass transition, melting points and heats of fusion
were determined by differential scanning calorimetry using a
Perkin-Elmer DSC-7. The DSC scans were obtained by first heating
copolymer samples to 200.degree. C. for 10 min, cooling them to
20.degree. C. at 20.degree. C. per minute, aging them at room
temperature for 24 h and then reheating from 0.degree. C. to
200.degree. C. at 20.degree. C./min. All DSC values in the tables
are reheat values. Scans to determine the glass transition
temperature were obtained by cooling the sample to -150.degree. C.
and then heating to 0.degree. C. at 40.degree. C./min. Two samples
of each polymer were run to ensure that the DSC measurements were
reproducible. Density was measured by a gradient column technique
in which a piece of molded specimen was allowed to sink to an
equilibrium level in an isopropyl alcohol/water column. The float
level of the specimen was compared to the float level of glass
beads of known density.
[0190] Tensile and recovery tests were performed with ASTM D-1708
dumbbell specimens (0.9 inch gauge length) die cut from compression
molded sheets. Crosshead separation rate was 25.4 cm/min for the
three cycle 100% strain test and 51 cm/min for all other tests.
Tensile modulus of elasticity was determined as the tangent slope
at lowest strain. Elongation after break (percent elongation
following break) was measured from benchmarks as immediate set of
the center 10 mm section of the specimen. The three cycle 100%
strain test was performed by elongating the specimen to twice the
original gauge length in three successive cycles of extension and
recovery, with 30 seconds hold at 100% elongation and 60 seconds
hold after crosshead recovery between cycles. In this test, the
cumulative set after the first two cycles is measured as the
elongation at which stress (or force) exceeds the baseline on the
third cycle.
[0191] Dynamic mechanical analysis (DMA) was performed with a Seiko
Instruments DMS 200 apparatus in tension mode at a frequency of 1
Hz. Temperature was scanned from -150.degree. C. to + 175.degree.
C. at a rate of 2.degree. C./min. Rectangular strip specimens were
prepared by trimming the end tabs of type D1708 specimens (the same
specimens prepared for tensile and recovery tests). The center 1.0
cm length was used as the gauge length between grips in the DMA
apparatus. Specimen width was 0.5 cm and thickness was 0.05-0.10
cm.
Examples 1-18; Runs A-V
[0192] The copolymerization of ethylene and 1-hexene was carried
out with metallocenes 1, 2, 3, 4, 5, 9 and 10 as described above.
Polymerization conditions are summarized in Table 1. The data and
characteristics of the resulting polymers are reported in Table
2.
[0193] As indicated in Table 2, Comparative Runs A-E, carried out
with bridged metallocene 1 yields random ethylene/hexene
copolymers. Polymers made with this metallocene containing 54-69
mol % ethylene are amorphous, exhibiting no melting point by DSC
analysis as indicated by "none" under the melt range and T.sub.m
columns. In contrast, metallocene 4 of the present invention yields
polymers containing 55-70% ethylene with melting points ranging
from 26-130.degree. C.
[0194] Reactivity ratios, r.sub.E and r.sub.H, for ethyl and hexene
insertion were calculated from diad distribution in .sup.13C NMR
data. For copolymers made from catalyst 3 incorporating hafnium as
the transition metal, the r.sub.E and r.sub.H are 2.5.+-.0.2 and
0.24.+-.0.03, respectively. These values compare to typical
r.sub.E's of 5-18 and r.sub.H's of 0.03 to 0.18 for polymers made
from other catalysts reported in Table 2. Thus, hafnium-containing
metallocene catalysts preferentially insert 1-hexene to a greater
proportion than observed in comparable zirconium-containing
metallocene catalysts.
[0195] The properties of the ethylene/hexene copolymers of Examples
5 and 6 are compared to representative other comparable polyolefin
elastomers and reported in Table 3. Comparative Run T is a
commercial Ethylene/Octene Elastomer obtained from Dow (Engage
8200.sub.TM), Comparative Run U is an Ethylene/Butene Elastomer
obtained from Exxon (Exact 4033.sub.TM), and Comparative Run V is a
polypropylene elastomer as described in Waymouth et al. U.S. Pat.
No. 5,594,080.
1TABLE 1 Polymerization Conditions For Ethylene-1-Hexene Copolymers
Ex. Cata- t.sup.b T.sup.c [Zr].sup.f MAO P.sub.e.sup.e
V.sub.hxe.sup.f V.sub.hxa.sup.g V.sub.total.sup.h (Run) lyst.sup.a
(min) (.degree. C.) (mM) (mg).sup.d (kPa) (mL) (mL) (mL) A 1 35 19
1.0 100 380 40 0 40 B 1 11 18 1.0 100 610 40 0 40 C 1 15 19 0.5 100
770 40 0 40 D 1 15 18 0.5 100 1060 40 0 40 E 1 7.5 18 0.5 100 1240
40 0 40 F 2 30 18 1.6 100 784 40 0 40 G 2 30 18 1.6 100 984 40 0 40
H 2 30 18 1.6 100 1140 40 0 40 J 3 30 18 6.3 100 1000 39 0 40 K 3
30 18 6.3 100 1210 39 0 40 L 3 30 18 6.3 100 1410 39 0 40 M 3 30 18
6.3 100 1830 39 0 40 N 4 180 17 6.3 100 470 39 0 40 1 4 120 18 6.3
100 640 39 0 40 2 4 180 18 6.3 100 991 39 0 40 3 4 180 18 6.3 100
1420 39 0 40 4 4 180 18 6.3 100 1210 39 0 40 5 4 180 18 13 200 1240
77 0 80 6 4 90 18 13 200 1450 40 38 80 7 4 90 18 13 200 1830 77 0
80 8 4 60 20 13 200 1420 20 59 80 9 4 60 18 6.3 100 970 0 40 40 10
9 30 18 6.3 100 956 39 0 40 11 9 30 18 6.3 100 1480 39 0 40 O 10 30
18 6.3 100 784 39 0 40 12 10 30 18 6.3 100 1030 39 0 40 13 10 30 18
6.3 100 1230 39 0 40 P 11 30 18 3.0 100 984 40 0 40 Q 11 30 18 3.0
100 1140 40 0 40 14 11 30 18 3.0 100 1470 40 0 40 R 12 30 18 2.4
100 811 40 0 40 S 12 30 18 2.4 100 977 40 0 40 15 12 30 18 2.4 100
1340 40 0 40 16 2/H.sub.2 45 19 13 200 1400 20 58 80 17 2/H.sub.2
45 18 13 200 1400 20 58 80 18 2/H.sub.2 45 18 13 200 1400 20 58 80
.sup.a1 = ethylenebisindenylzircon- ium dichloride (bridged); 2 =
bis(2-phenylindenyl)zirconium dichloride; 3 =
bis(2-phenylindenyl)hafnium dichloride; 4 =
bis(2-(3,5-trifluoromethylphenyl)indenyl)zirconium dichloride; 9 =
(2-(3,5-trifluoromethylphenyl)indenyl)(1-methyl-2-(3,5-trifluoromethy-
lphenyl)indenyl)zirconium dichloride (four rotational states); 10 =
bis(2-(3,5-tert-butyl-4-methoxyphenyl)indenyl)zirconium dichloride;
11 = bis(2-(3,5-trimethylsilylphenyl)indenyl)zirconium dichloride;
12 = bis(2-(3,5-tert-butylphenyl)indenyl)zirconium dichloride,
.sup.bt = polymerization time. .sup.cT = polymerization temperature
.sup.dAmount of MAO (Akzo Type 4) used for the reaction.
.sup.eP.sub.e = ethylene pressure (absolute). .sup.fV.sub.Hxe =
volume of 1-hexene used for the polymerization. .sup.gV.sub.Hxa =
volume of hexanes diluent used for the reaction. .sup.hV.sub.Total
= total volume used for the polymerization, V.sub.Total -
(V.sub.Hexene + V.sub.Hexane) = volume of metallocene stock
solution (in toluene) used. .sup.fZirconium concentration in
micromoles.
[0196]
2TABLE 2 Property data for Ethylene-1-Hexene Copolymers Melt Ex.
Prod..sup.b % T.sub.q.sup.d Range T.sub.m .DELTA.H.sub.f
M.sub.w.sup.e (Run) Catalyst.sup.a (.times.10.sup.-4) E.sup.c
(.degree. C.) (.degree. C.) (.degree. C.) (J/g) (.times.10.sup.-3)
PDI.sup.e A 1 11.9 56 -72 none none 0 53 2.2 B 1 97.2 65 -76 none
none 0 52 2.1 C 1 96.6 69 -75 none none 0 61 2.2 D 1 85.2 78 -77
37-45 43 0.3 75 2.4 E 1 209.2 83 -74 33-43 40 4.7 71 2.2 F 2 4.2 54
-69 none none 0 1176 3.2 G 2 5.7 60 -70 none none 0 1353 5.5 H 2
7.4 65 -74 none none 0 1474 7.4 J 3 2.0 41 -61 none none 0 1293 3.2
K 3 2.4 44 -67 none none 0 1508 2.5 L 3 3.0 49 -65 none none 0 1793
2.8 M 3 0.96 63 -69 30-50 40 1.0 1287 4.8 N 4 0.24 42 -73 none none
0 554 7.4 1 4 0.30 55 -67 26-126 39, 116 2.7 691 6.3 2 4 0.30 66
-72 28-130 40, 120 8.0 994 7.6 3 4 1.1 71 nd.sup.f 27-80, 38, 121
4.2 1076 9.0 89-127 4 4 0.4 72 -72 27-128 42, 118 6.6 1404 5.8 5 4
0.30 73 -72 23-130 37, 119 16 826 6.3 6 4 1.4 80 -70 16-116 25, 86
15.7 1052 5.5 7 4 1.1 79 nm.sup.g 25-125 31, 45, 80, 8.8 nm.sup.g
nm.sup.g 114 8 4 2.6 90 -59 11-117 20, 40, 105 31 1221 6.2 9 4 1.5
100 nd.sup.f 100-145 133 136 1534 4.7 10 9.sup.h 0.60 76 -71 40-68,
92- 44, 113 1.9 700 4.8 120 11 9.sup.h 1.2 84 -72 20-67, 78- 28,
107 4.0 901 5.8 114 O 10 0.9 51 nd none none 0 1193 4.1 12 10 1.0
57 -74 34-127 117 4.0 1335 7.8 13 10 1.2 63 -76 29-135 117 5.2 1758
7.9 P 11 1.5 53 -86 none none 0 1494 3.7 Q 11 2.0 58 -92 none none-
0 1680 6.8 14 11 3.2 66 -91 29-80, 40, 120 0.8 1739 4.8 100-128 R
12 1.8 44 -65 none none 0 1019 3.3 S 12 1.8 55 -68 none none 0 1180
4.0 15 12 1.4 62 -72 24-120 35, 120 2.2 1369 3.9 T
ENGAGE.sub..TM..sup.h -- 87 -64 20-70 66 36 77 2.4 U
EXACT.sub..TM..sup.i -- 85 -64 20-70 64 50 nm.sup.g nm.sup.g
.sup.a1 = ethylenebisindenylzirconium dichloride (bridged); 2 =
bis(2-phenylindenyl)zirconium dichloride; 3 =
bis(2-phenylindenyl)hafnium dichloride; 4 =
bis(2-(3,5-trifluoromethylphenyl)indenyl)zirconium dichloride; 9 =
(2-(3,5-trifluoromethylphenyl)indenyl)(1-methyl-2-(3,5-trifluoromethylp-
henyl)indenyl)zirconium dichloride (four rotational states); 10 =
bis(2-(3,5-tert-butyl-4-methoxyphenyl)indenyl)zirconium dichloride;
11 = bis(2-(3,5-trimethylsilylphenyl)indenyl)zirconium dichloride;
12 = bis(2-(3,5-tert-butylphenyl)indenyl)zirconium dichloride,
.sup.bProd. = productivity measured in kg of polymer produced per
mol of metal per hour. .sup.cMole % E determined by .sup.13C NMR
spectroscopy. .sup.dHalf Cp extrapolated. .sup.eDetermined by high
temperature GPC. .sup.fnd = not detected. .sup.gnm = not measured.
.sup.hCatalyst 9 exhibits four rotational symmetry states (FIG.
2).
[0197]
3TABLE 3 Mechanical Properties of Polyolefin Elastomers Polymer Ex.
5 Ex. 6 Ex. 8 Run T Run U Run V Engage Exact Polypropylene 8200
4033 37% m4 Comonomer Hexene Hexene Hexene Octene Butene None Mole
% Ethylene 73 80 89 87 89 0 PE Melt Index nd nd nd 5.0 0.8 Mn
(.times.10.sup.3) 130 191 196 32.7 Mw (.times.10.sup.3) 826 1052
1221 77.4 nd 386 Mw/Mn (PDI) 6.3 5.5 6.2 2.4 T.sub.m range
(.degree. C.) 23-130 16-116 11-117 20-70 20-70 40-160 T.sub.m peak
(.degree. C.) 119 25, 86 20-105 66 64 148 .DELTA.H.sub.f (J/g) 16.2
15.6 26 36 50 -- T.sub.q (.degree. C.).sup.a -72 -70 -59 -64 -56 --
Density (g/cc) 0.8682 0.8694 0.8819 0.87 0.88 0.8663 Tensile 3.6
4.2 8.8 9.6 16.9 12.3 Strength (MPa) Tensile 2.9 4.0 10.3 6.9 12.3
8.9 Modulus (MPa) Elongation at 565 .+-. 62 428 360 1130 750 830
Break (%) Elongation 90 .+-. 17 26 57 300 210 34 after Break (%)
100% Elongation 3 Cycle Test: % stress relaxation, 33 17 17 23 23
39 30 sec, 1st cycle % retained force, 24 41 29 28 20 29 2nd cycle
% set, cumulative 19 13 13 13 11 7 Stress Relaxation Test 50%
elongation, 51 33 25 28 28 48 5 min .sup.aDetermined by Dynamic
Mechanical Analysis (DMA).
[0198] As evident from Table 3, the polyolefin elastomers of
Examples 5, 6 and 8 have a similar density and comparable
elastomeric properties. However, the copolymer elastomers of
Example 5 and 6 have a particularly useful combination of
properties that includes a low glass transition temperature
(Tg=-70.degree. C.) and melting ranges that extend to 130.degree.
C. The copolymers of Example 5 and Comparative Runs T and U
illustrate that while the heat of fusion from Example 5 is lower
(.DELTA.H.sub.f (J/g)=16.2 vs. 36 and 50 for Engage and Exact), the
melting point of the copolymer of Example 5 is 119.degree. C. It is
unexpected that this high melting point is achieved at a much lower
mol % ethylene (73 mol % versus 87 or 89 mol % for Engage and
Exact, respectively).
[0199] It is evident that the polymers of the present invention,
and the polymerization catalysts and processes by which the
polymers are produced will have wide applicability in industry,
inter alia, as elastomers having higher melting points than
currently available elastomers, as thermoplastic materials, and as
components for blending with other polyolefins for predetermined
selected properties, such as raising the melting point of the
blend. As seen in Table 3 and the accompanying discussion, typical
polymers of this invention, while they have degrees of
crystallinity lower than (Examples 5, 6, 8), or similar to
(Examples 20, 21) that of Dow's Engage 82.sub.tm and EXXON's
4033.sub.tm, they have a broader melting point range that extends
to higher temperatures, e.g., to 130.degree. C., and above.
[0200] Solvent Extraction
[0201] The compositional homogeneity of copolymers of this
invention was investigated by extracting the copolymers in boiling
solvents such as ether and hexanes. Copolymers were extracted
sequentially into solvents of increasing boiling point to separate
components of different molecular weight and crystallinity. Diethyl
ether, pentane, THF, hexanes, cyclohexane, and heptane were used.
The copolymer (1-2 g) was placed in an extraction thimble and
loaded into a Kumigawa extraction apparatus. The polymer was
extracted into refluxing solvent for 24-48 h. The solvent soluble
material was precipitated in stirring methanol and then dried in a
vacuum oven at 40.degree. C. The solvent-insoluble material was
dried in the vacuum oven while still in the extraction thimble. The
process was then repeated on the solvent insoluble material with
higher boiling solvents until all the material dissolved. For the
fractionation experiments listed in Table 9, the heptane extraction
was performed first. The heptane soluble material was then
extracted with diethyl ether.
[0202] The results of a fractionation experiments on the copolymer
samples of Example 2 and 3 are reported in Table 4. A portion of
ethylene/hexene copolymer produced in Examples 2, and 3 containing
66 and 71 mole percent ethylene units, respectively, were
fractionated with refluxing ether and hexanes. A sample of
copolymer was extracted into refluxing ether and the resulting
insoluble component then was extracted with refluxing hexanes. The
results shown in Table 4 demonstrate that the composition
distribution for fractions of differing crystallinities is narrow
and within 8 mole % of the mean composition distribution.
4TABLE 4 Solvent Fractionation of Ethylene/Hexene Copolymer Example
Sample % Wt % E.sup.a T.sub.m, .degree. C. Melt Range, .degree. C.
2 Whole 100 66 63, 114 61-81, 82-124 ES.sup.b 16 59 42 35-50 EI 84
72 41, 118 29-126 EI/HxS.sup.c 80 69 45 25-85 3 Whole 100 71 39,
119 29-75, 76-126 ES.sup.b 23 63 35 30-43 EI.sup.c 77 75 35, 119
24-129 EI/HxS.sup.c 64 72 34, 119 27-126 HxI.sup.e 13 78 35, 59,
117 24-128 .sup.adetermined by solution .sup.13C NMR. .sup.bES =
diethylether soluble. .sup.cEI/HxS = diethylether insoluble/hexane
soluble. .sup.dHxI = hexane insoluble.
[0203] The mole fraction of ethylene in the various fractions of
the copolymer were all within 10% of the mean mole percent ethylene
of the copolymer sample, indicating that these materials had a
narrow composition distribution. Solvent fractionation experiments
were performed on a sample of ethylene/1-hexene copolymer (Example
7) containing 79 mole percent ethylene prepared with Catalyst 4.
The copolymer was extracted for 48 hours with ether, and the
ether-insoluble portion then was extracted with pentane for anther
48 hours. This procedure was repeated using tetrahydrofuran (THF),
hexanes, cyclohexane, and heptane. The results are shown in Table
5. The ethylene content of the fractions lie within 11 mole % of
that observed for the whole polymer, although the crystallinities
for the fractions as reflected in the DSC data vary widely.
5TABLE 5 Solvent Fractionation Of Ethylene-1-Hexene Copolymer
Weight mol T.sub.m (range) T.sub.m (peaks) .DELTA.H.sub.f Fraction
% % E (.degree. C.) (.degree. C.) (J/g) Ex. 7, Whole 100 79 25-125
31, 45, 80, 8.8 114 Ether Soluble 23 71 28-46 36 0.2 Pentane
Soluble 6 75 28-60 37 0.8 THF Soluble 38 77 26-87, 33, 112 3.7, 0.1
99-112 Hexane Soluble 17 80 23-123 34, 113 6.6 Cyclohexane 11 89
22-120 38, 84 23.7 Soluble Heptane Soluble 5 91 24-118 33, 80, 104
17.9
[0204] Supercritical Fluid Fractionation
[0205] The solubility of a polymer in a typical organic solvent
depends on the identity of the solvent and temperature. Higher
molecular weight and more highly crystalline components tend to
dissolve at reflux in higher boiling solvents. Supercritical fluids
have an added advantage in that the solubility of the polymer can
be tuned by the pressure of the system. As pressure is increased,
components higher in molecular weight and crystallinity will
dissolve. This unique feature of supercritical fluids can be
exploited to separate polyolefin homo- and copolymers into
well-defined fractions. Supercritical fluid fractionation
techniques have been successfully applied to the fractionation of
linear low density polyethylenes according to molecular weight and
degree of short chain branching.
[0206] An ethylene-1-hexene copolymer containing 90 mol % E (See
Example 19, below) was fractionated using a supercritical fluid
extraction technique. Fractionation of the copolymer using
supercritical propane was performed as follows: The copolymer
sample was cut into small pieces and distributed in the
fractionation chamber over surface area enhancing packing. Irganox
1010' (a phenolic anti-oxidant stabilizer, Ciba) was added to
prevent degradation of the copolymer during the experiment. At a
temperature above the melting point of the copolymer, supercritical
propane was used to extract the sample over an increasing pressure
profile ranging from 2000 psi-10,000 psi (14 MPa to 70 MPa). This
procedure was expected to fractionate the material by molecular
weight. This method involved extracting the copolymer into
supercritical propane at increasing pressures (2000-10000 psi;
14-70 MPa) while maintaining a constant temperature (200.degree.
C.) in the extraction chamber. Because the fractionation was run
above the highest peak melting temperature of the copolymer,
fractionation was expected to occur strictly according to molecular
weight.
[0207] Ethylene-1-hexene copolymer fractions collected according to
this fractionation method exhibited very consistent ethylene
contents (mol % E=88.+-.3). The DSC profiles of all the fractions
exhibited broad, bimodal melting transitions. The heats of fusion
measured by DSC were similar for all fractions
(.DELTA.H.sub.f=8-14.5 J/g). The average molecular weights
(M.sub.v) of representative fractions were calculated from the
intrinsic viscosities of the materials. The molecular weight
tracked with the pressure of the supercritical fluid used to
extract the copolymer M.sub.v=55,000-880,000). The Results are
shown in Table 6.
6TABLE 6 Supercritical Fluid Fractionation Of Ethylene-1-Hexene
Copolymer Propane Pressure wt. % mol T.sub.m (.degree. C.) T.sub.m
(peaks) .DELTA.H.sub.f.sup.b .DELTA.H.sub.f M.sub.v.sup.c (psi)
Collected % E.sup.a (range) (.degree. C.) (J/g) (Total)
(.times.10.sup.-3) 2000 5.3 89 .+-. 1 31-73 39, 48 3.1 8.2 55 (14
MPa) 86-143 120, 132 5.1 3000 9.7 88 .+-. 2 23-78 32, 48 12.1 14.5
(21 MPa) 96-122 116 2.4 4000 13.5 88 .+-. 1 24-76 32, 48 10.1 12.6
(28 MPa) 87-122 113 2.5 5000 7.9 89 .+-. 1 25-73 32, 47 8.6 10.9
180 (35 MPa) 81-122 114 2.3 6000 9.4 88 .+-. 1 24-76 33, 48 9.3
12.3 (41 MPa) 77-122 114 3.0 7000 8.2 88 .+-. 1 25-75 33, 48 9.4
12.2 (48 MPa) 79-121 112 2.8 8000 88 .+-. 2 25-76 33, 47 8.9 10.9
(55 MPa) 80-120 112 2.0 9000 6.3 88 .+-. 3 26-73 32, 48 9.5 11.8
(62 MPa) 85-120 112 2.3 10,000 7.1 88 .+-. 3 23-77 32, 47 10.1 12.6
(70 MPa) 80-120 112 2.6 Insoluble 23.2 87 .+-. 2 24-72 33, 48 11.4
13.2 880 Material 82-121 112 1.8 Whole.sup.d 100 90 24-86 33, 44
10.3 16.0 90-122 114 5.7 .sup.aCalculated by .sup.13C NMR.
.sup.bThe total heat of fusion is divided into components which
correspond to the low and high temperature melting ranges.
.sup.cDetermined from intrinsic viscosity data. .sup.dData for the
unfractionated copolymer.
[0208] Examples 19-21
[0209] Since some of the elastomeric properties exhibited in some
of the copolymers of this invention may be due to high molecular
weight of the materials, copolymerizations were performed in the
presence of hydrogen which will lower polymer molecular weight.
Three polymerizations were performed under identical conditions in
which two were carried out in the presence of hydrogen
[0210] The polymerizations were conducted to prepare
ethylene-1-hexene copolymers containing 10 mol % hexene in the
presence of hydrogen for molecular weight control. Polymerizations
were conducted as described above using Catalyst 4 with MAO except
that in Examples 20 and 21, 2.5 mmol and 5.0 mmol of hydrogen were
added to the batch polymerization reactor, respectively. Properties
of the resulting copolymers are shown in Tables 7 and 8. Since the
concentration of hydrogen in the batch reactor decreased during the
polymerization, the polydispersities were high since polymers of
differing molecular weights will be formed as the hydrogen
concentration decreases. Addition of hydrogen produced products
which were plastomers rather than elastomers as evidenced by a
substantial increase in tensile modulus. Solvent extraction of the
products of Examples 19-21 were performed using the method
described above. Results are shown in Table 9. Again, composition
distribution among the solvent fractions is narrow within
.+-.10%.
[0211] As expected, the molecular weights of the copolymers were
lowered dramatically when hydrogen was introduced to the system.
The polydispersities of the copolymers were higher for materials
prepared in the presence of hydrogen. The melting transitions
measured by DSC spanned a comparable range for the three copolymers
(T.sub.m=20-127.degree. C.), however, the heats of fusion were
significantly different. The crystallinity of the copolymers
increased substantially as the amount of hydrogen in the system
increased.
[0212] The high temperature component of the melting transition
became sharper for reactions carried out in the presence of larger
amounts of hydrogen as shown in FIG. 3. Trace a) is with no H.sub.2
added (Ex. 19); Trace b) has 2.5 mmol H.sub.2 (Ex. 20), and Trace
c) has 5.0 mmol H.sub.2 added (Ex. 21).
7TABLE 7 Polymerization In The Presence Of Hydrogen.sup.a H.sub.2 %
Melt Range T.sub.m .DELTA.H.sub.f M.sub.n.sup.d M.sub.w.sup.d Tg
Ex. (mmol).sup.b E.sup.c (.degree. C.) (.degree. C.) (J/g)
(.times.10.sup.-3) (.times.10.sup.-3) PDI.sup.e Density (.degree.
C.) 19 0 90 24-86, 33, 44, 16.0 nd nd nd 0.8819 nd 90-122 114 20
2.5 90 23-127 33, 115, 48.3 11.3 310 27.4 0.8919 -54 119 21 5.0 90
25-126 34, 117, 61.9 3.4 50.8 14.9 0.9133 -61 120 .sup.aReaction
Conditions: T = 18.degree. C., t = 45 min., [Zr] = 13 mM, MAO = 200
mg, P.sub.e = 188 psig, V.sub.Hexene = 20 mL, V.sub.Hexanes = 58
mL, V.sub.Total = 80 mL. .sup.bThe amount of hydrogen added was
estimated using the ideal gas law. .sup.c% E is given as a mol %.
.sup.dMeasured by high temperature GPC. .sup.ePDI =
M.sub.w/M.sub.n. .sup.fMolecular weights were not determined (nd)
for this sample.
[0213]
8TABLE 8 Mechanical Properties of Ethylene-Hexene Copolymers
Example 19 20 21 Tensile Strength (MPa) 8.8 10.9 5.4 Tensile
Modulus (MPa) 10.3 24.9 39.9 Elong. at Break (%) 360 674 636 Elong.
after Break (%) 57 246 393 100% Elongation, 3 Cycle Test:.sup.a
stress relax. (%), 17 28 39 30 seconds, 1st cycle % retained force,
2nd cycle 29 4.3 0 % set cumulative 13 28 57 Stress Relaxation, 50%
elongation, 5 min 25 40 13 .sup.aThree extension cycles to 100%
elongation, 30 seconds hold at extension, 60 seconds at recovery.
Set values are based on strain at which stress exceeds baseline on
third extension.
[0214]
9TABLE 9 Solvent Fractionation of Ethylene-1-Hexene Copolymers wt.
mol T.sub.m (range) T.sub.m (peaks) .DELTA.H.sub.f Fraction %.sup.a
% E (.degree. C.) (.degree. C.) (J/g) Whole 100 90 11-117 20, 40,
105 31 (No H.sub.2, Ex. 19) Heptane Soluble.sup.b 15 89 24-116 33,
101 17 Heptane Insoluble.sup.b 85 88 21-123 33, 48, 112 21.2
Heptane Soluble 2.sup.c 58 87 26-121 35, 50, 105 19.1 Heptane
Sol./Insol..sup.c,d 20 91 nd.sup.e nd.sup.e nd.sup.e Heptane
Insoluble 2.sup.c 22 91 25-123 38, 52, 112 33.7 Whole 100 90 23-127
33, 115, 119 48.3 (2.5 mmol H.sub.2, Ex. 20)) Ether Soluble 13 85
26-62 35, 50 13.0 Ether Insol./ 82 89 27-122 32, 109 49.0 Heptane
Sol. Heptane Soluble 95 90 25-122 32, 55, 106, 35.6 113 Heptane
Insoluble 5 96 26-130 123 81.5 Whole 100 90 25-126 34, 117, 120
61.9 (5 mmol H.sub.2, Ex. 21) Ether Soluble 34 85 27-62 33, 51 13.9
Ether Insol./Heptane 60 93 24-124 33, 82, 107, 88.8 Sol. 115
Heptane Soluble 94 90 24-123 30, 40, 95, 112 58.8 Heptane Insoluble
6 100 60-139 127 91.8 .sup.a(wt. % heptane insoluble) + (wt. %
heptane soluble) = 100. (wt. % ether soluble) + (wt. % ether
insoluble) = (wt. % heptane soluble). .sup.bThe material was
extracted with heptane for 24 h. .sup.cThe material was extracted
with heptane for 72 h. .sup.dThis fraction was initially soluble in
heptane but precipitated in the receiving flask. .sup.end = not
determined.
[0215] Segregation Fractionation Technique (SFT)
[0216] The average degree of short chain branching in an
ethylene-.alpha.-olefin copolymer can be independently ascertained
by .sup.13C NMR (SCB/1000 C's=1000{% O/[n(% O)+2(% E)]}; % O=mol %
.alpha.-olefin in the copolymer, n=length of the .alpha.-olefin,
SCB/1000 C's=the number of short chain branches per 1000
carbons).
[0217] Ethylene-.alpha.-olefin copolymers can be fractionated in
situ by DSC by subjecting the material to a series of isothermal
crystallization steps beginning in the melt and proceeding at
successively lower temperatures. Because uninterrupted ethylene
sequences of variable length form crystals of differing sizes and
melting points, this procedure separates the DSC melting profile
into a series of peaks which correspond to sections of the polymer
with different degrees of short chain branching. The
ethylene-1-hexene copolymer of Ex. 7 and its selected fractions
reported in Table 5 were analyzed by this segregation fractionation
technique (SFT). The copolymers were initially heated to the melt
(180.degree. C.) and then cooled to 120.degree. C. The materials
were isothermally annealed at this temperature for 2 h and then the
temperature was quickly lowered by 15.degree. C. The procedure was
repeated until the temperature reached 30.degree. C. The samples
were then slowly reheated from 30 to 180.degree. C. to record the
fractionated DSC profile.
[0218] The ethylene-1-hexene copolymers of Ex. 4 was also
fractionated using this SFT technique and the result is shown in
FIG. 4.
[0219] The degree of short chain branching measured by .sup.13C NMR
and estimated by SFT are reported in Table 10. For the whole
polymer and the ether, pentane, THF, and hexanes soluble
components, a higher degree of short chain branching was observed
by 13C NMR than estimated by DSC. For the cyclohexane and heptane
soluble components, the short chain branching distributions
estimated by DSC overlap those determined by 13C NMR. Since the SFT
method assumes a random polymer to estimate the number of short
chain branches, this data is indicative of a blocky polymer (more
branches are needed to depress the melting point).
[0220] Comparison to Random Copolymers
[0221] Many of the copolymers of this invention show an upper peak
melting temperature above that expected for a random copolymer of
the same monomer unit composition.
[0222] Mandelkern and coworkers examined the melting behavior of a
variety of random ethylene-a-olefin copolymers over a range of
compositions. For details, see Alamo and Mandelkern, Thermochemica
Acta, 1994, v.238, pp. 155-201, incorporated by reference herein.
It was determined that a plot of T.sub.m vs composition was
essentially independent of the identity of C.sub.nH.sub.2n when n
is greater than or equal to four. However, for copolymers with a
given ethylene content, the melting temperatures were affected by
the molecular weight of the material. The peak melting temperature
decreased by 7-8.degree. C. as the molecular weight of the
copolymer increased from 4500-500,000. Ethylene-1-hexene copolymers
produced with metallocene 4 and their solvent fractions were
compared to the random copolymers described by Mandelkern
(M.sub.w=90,000.+-.20,000) to determine if these materials exhibit
melting behavior consistent with a non-random sequence distribution
(FIGS. 5 and 6). In particular, a high ethylene content, low
molecular weight sample (M.sub.n=3,400, M.sub.w=50,800; Example 19)
was compared to the Mandelkern data. Preferably, comparison of
upper peak melting temperature of products of this invention to
random copolymers with similar composition also is done with
polymers with similar molecular weights. The ether
insoluble/heptane soluble fraction comprised 60% of this copolymer.
This solvent fraction exhibits a maximum peak melting temperature
approximately 20.degree. C. higher than the random copolymers
considered by Mandelkern. This suggests that this fraction contains
long crystallizable sequences. As this fraction is soluble in
heptane the crystallizable sequences are not derived from an
ethylene homopolymer. These results indicate that at least 60% of
this copolymer exhibits a blocky character.
[0223] A high molecular weight copolymer prepared with metallocene
4 and containing 79 mol % E (M.sub.w.about.1,000,000; Example 7,
Table 5) was also compared to the random copolymers reported by
Mandelkern (FIG. 6). In particular, the hexanes soluble portion of
the material exhibits a maximum peak melting temperature over
50.degree. C. higher than a random copolymer with identical
composition. The THF and heptane soluble portions of this copolymer
also exhibit melting temperatures that are higher than expected for
a random copolymer. These results suggest that a significant
portion of this copolymer is blocky in character.
[0224] These results show it is not only the whole polymer that
exhibits melting temperatures that are higher than expected. As
described above and depicted in FIGS. 5 and 6, certain solvent
fractions exhibit substantially higher melting temperatures than
observed for random copolymers of similar composition. Once the
solvent extractions have been performed, the fractionated materials
are less likely to be simple blends of copolymers with different
melting temperatures.
10TABLE 10 Short Chain Branching and Solvent Fractions
Distributions for an Ethylene-1-Hexene Copolymer (Example 7)
SCB/1000 C's Fraction mol % E .sup.13C NMR SFT Whole 79 74 12-53
Ether Soluble 71 92 54.sup.a Pentane Soluble 75 83 54.sup.a THF
Soluble 77 79 13-53 Hexanes Soluble 80 71 8-53 Cyclohexane Soluble
89 45 12-53 Heptane Soluble 91 38 13-53 .sup.aSFT was not applied
to these fractions because of their low crystallinity and narrow
melting transitions. The degree of short chain branching was
calculated from the peak melting temperature observed by standard
DSC techniques.
Examples 22-24
[0225] A series of ethylene/1-hexene copolymers were prepared using
the Catalyst 4 and the polymerization procedures described above.
Results are listed in Table 11.
11TABLE 11 High Ethylene-Content Copolymers T.sub.pol Mol Melt
T.sub.m .DELTA.Hf M.sub.n M.sub.w M.sub.pk Density Ex. .degree. C.
% E Range .degree. C. .degree. C. J/g .times.10.sup.-3
.times.10.sup.-3 M.sub.w/M.sub.n .times.10.sup.-3 (g/cc) 22 18 93
25-121 69, 105 72 576 2010 3.5 1280 <.910 23 20 98 25-119 95,
109 107 538 1980 3.7 1380 <.910 24 18 99 30-128 119 134 518 1790
3.5 1220 .916
[0226] The samples were analyzed by DSC. These inventive copolymers
illustrate an ethylene-1-hexene copolymer having a broad melting
transition(.about.100.degree. C.), a relative high polydispersity
(3.5-3.7), a high upper peak melting temperature, and a narrow
composition distribution. In Examples 22 and 23 the melting
transition is bimodal as measured by DSC.
Example 25--Run W
[0227] Ethylene-1-hexene copolymer was made in a 1-liter stirred
autoclave reactor which was heated to 90.degree. C. and purged with
nitrogen. The reactor then was charged with isobutane (750 ml) and
tri-isobutylaluminium (3.7 ml of 1M solution in hexanes, supplied
by Aldrich), and temperature adjusted to 70.degree. C. After 1
hour, the reactor was charged with 1-hexene (dry, deoxygenated; 10
ml), and ethylene (7.3 bar). In a glovebox, a toluene solution of
bis(3-5-di-tertbutylphenyl-2-indenyl)hafnium dichloride (Catalyst
12, 4.05 mg in 1 ml toluene) was mixed with a toluene solution of
methylaluminoxane (2.7 ml of 1.78M; supplied by Albemarle). The
mixture was injected into the reactor under nitrogen, and ethylene
added continuously to maintain a constant pressure. After 1 hour,
the reactor was vented and cooled to 20.degree. C. Ethylene-hexene
copolymer (16.4 g) was recovered.
[0228] A sample of the ethylene-1-hexene copolymer (Ex. 25) made
according to this invention, and a typical Ziegler LLDPE (Run W)
were pressed into films at 150.degree. C. and then quench cooled.
The copolymer of this inventions demonstrated unexpected decrease
in haze and increase in clarity compared to the conventional
material as presented in Table 12.
12TABLE 12 Copolymer Film Properties Run W Ex. 25 Mw (x10-3) -- 200
Mn (x10-3) -- 57 Mw/Mn -- 3.5 SCB/1000 C. .about.20 21.5 Density
(g/cc) 0.916 0.916 Thickness (mm) 500 500 Gloss (%) - ASTM D2457 53
67 (96) .sup.b Haze (%) - ASTM D1003 89 41 (23) .sup.b Clarity (%)
- ASTM D1746 8 4 (7) .sup.b Yield Strength (MPa) .sup.a 12.54 8.84
Ultimate Tensile Strength (MPa) .sup.a 27.96 14.58 Elongation (%)
.sup.a 691 360 1% Secant Modulus (MPa) .sup.a 212.2 104.2 .sup.a
Tensile measurements were carried out at 23 C. on 15 mm .times. 40
mm gauge length strips at 500 mm/min test rate. Tensiles measured
according to ISO 1184, DIN 53455. .sup.b Values in parentheses were
measured after a second pressing of the samples to eliminate
bubles.
[0229] Industrial Applicability
[0230] It is clear from the general description and the properties
tests in the Examples that the copolymers of the invention have
wide industrial applicability for use in film and fiber formation,
cast extruded and smolded plastic products ranging from
thermoplastic plastomers to elastomers.
[0231] Copolymer produced according to the method of this invention
may be formed into pellets by melt extrusion and chopping, which
then may be used to form useful articles such as extruded pipe,
molded fittings and containers. Copolymers of this invention may be
combined with effective amounts of typical polymer additives known
to the art such as heat and uv stabilizers, anti-oxidants, acid
scavengers, anti-static agents, and the like. In addition, the
copolymers may be combined with colorants and fillers such as glass
fiber and talc.
[0232] Products made from the copolymers of this invention may be
formed by techniques known to the art, such as casting, pressing,
blowing, and extruding. Films formed from the copolymers may have
thicknesses range from about 0.1 mil (0.00254 mm) to 100 mil (2.54
mm) or more. Typical film thickness may be about 0.25 mil (.00635
mm) to about 50 mil (1.27 mm) and preferably about 0.5 mil (0.0127
mm) to 20 mil (0.508 mm). Typical films show improved optical
properties such as reduced haze and increased clarity compared to
typical linear low density polyethylenes. Other useful articles may
be manufactured from the copolymers of this invention by
conventional techniques such as molding or extrusion.
[0233] It should be understood that various modifications within
the scope of this invention can be made by one of ordinary skill in
the art without departing from the spirit thereof. We therefore
wish this invention to be defined by the scope of the appended
claims as broadly as the prior art will permit, and in view of the
specification if need be.
* * * * *