Note: Descriptions are shown in the official language in which they were submitted.
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Polymerization of Crystalline Copolymers of Olefins and Cyclic Olefins
Field of the Invention
The invention relates to a polymerization process for the
preparation of semi-crystalline copolymers of olefins and cyclic olefins
without ring-opening metathesis. Specific catalysts suitable in the
process include bridged, monocyclopentadienyl catalyst compounds
with alumoxane or ionizing catalyst activators.
Background
The polymerization of cyclic olefins, either alone, or with
copolymerizable monomers, particularly olefins, has been significantly
advanced with the discovery of the effectiveness of metallocene
catalysts for coordination polymerization. Crystalline homopolymers
can be prepared from the use of stereorigid, chiral metallocenes that
yield conformationally regular or stereospecific polymers. See, New
Materials by Polymerization of Cyclic Olefins with Metallocene
Catalysts, W. Kaminsky, Paper for METCON '93, Houston, Tx, May
26-28, 1993, p. 325-335. Copolymerization with a-olefins can result in
elastomeric polymers due to disruption of the v-olefin crystal)inity
caused by the olefin incorporation. See, U.S. patent 5,204,429.
More recently it has been discovered that by careful selection of
the ligand structure of the metallocene catalysts, copolymers having
crystalline attributes can be prepared by copolymerizing olefins with
the cyclic olefins. U.S. patent 5,324,801 describes a process for the
preparation of cycloolefin copolymers having from 1 to 80% of at least
one cyclic olefin comprising copolymerization with an acyclic olefin in
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the presence of sandwich structured metallocenes where the
sandwiching ligands are connected or bridged so as to form a ring.
Preferred copolymers are said to have incorporation ratios of 40:60 to
60:40 of the cyclic olefin to acyclic olefin. Using the sandwich
metallocenes exhibiting C 1 symmetry, with the preferred ligands being
fluorenyl and cyclopentadienyl, copolymers of alternating sequence
ethylene and either of norbornene or tetracycloclododecene were
prepared having crystalline melting points of 235 °C to 335 °C
and
molar ratios ranging from 50:50 to 41:59, cyclic olefin to acyclic olefin.
Due to transparency the polymers are said to be suitable as glass
substitutes, and suitable in polymer alloys. Further product
description appears in Cherdon, et al, Cycloolefin Copolymers: A
New Class of Transparent Thermoplastics, Angew. Chem. 223,
121-133 (1994).
Since these crystalline and semi-crystalline copolymers of
ethylene, a-olefins, and cyclic olefins exhibit uniquely interesting
physical properties, alternative means of preparing them, with
potential improvements in ease of catalyst synthesis, increased
polymerization e~.ciencies, increased cyclic olefin incorporation
e~ciencies and differing copolymer product characteristics are of great
interest. Accordingly work was done to develop catalyst systems
different from those previously discovered to be capable of such
copolymerization processes.
Summary of the Invention
The invention thus is a copolymerization process suitable for the
preparation of high crystalline melting point cyclic olefin copolymers
comprising contacting ethylene and at least one cyclic olefin, under
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suitable polymerization conditions, with an active polymerization
catalyst comprising a Group 4 transition metal compound containing
an asymmetrically substituted monocyclopentadienyl ancillary ligand,
a bulky substituent-containing heteroatom ligand, the
monocyclopentadienyl and heteroatom ligands being covalently
bridged.
Description and ~zamples
1o The cyclic olefin copolymers for which the invention process is
suitable include those having both sequence regularity and
conformational regularity. Sequence regularity means here essentially
alternating sequences of cyclic olefin monomer and ethylene.
Conformational regularity, or sterospecificity, is the result of consistent
molecular coordination geometries. These characterizing features
assure that the copolymer can exhibit initial crystalline melting points
from about 150 °C to 350 °C, particularly 200 °C to 300
°C, as
measured by differential scanning calorimetry (DSC) conducted at a
heating rate of 10 °C per minute from -50 to 350 °C. These
copolymers
typically have an intrinsic viscosity of 0.05 dl/g to 20 dl/g as measured
at 135 °C in decalin. Molecular weight distribution, or polydispersity
(MWD), is typically narrow, ranging from about 1.1 up to 6.0,
preferably 1.2 to 4.5, more preferably 2.0 to 4.0 as calculated from
molecular weights measured by gel permeation chromatography (GPC)
referenced to a known polyethylene standard in accordance with
traditional methods. Although an MWD <2.0 is not typical in
traditional Ziegler-Natta polymerization, the use of certain
polymerization conditions for the copolymerization in accordance with
this invention can result in polymerization analogous to "living"
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anionic polymerizations which are typified with MWD
characterizations below 2Ø
Ethylene is the preferred comonomer in that using the catalyst
system of this invention, C3 and higher carbon number a-olefins are
not typically capable of copolymerization sequences consistent with
production of the semicrystalline polymers of the invention. This
phenomena is notable, in the prior art relating to cyclic olefin
copolymers, the C3 and higher carbon number a-olefins are typically
i0 said to be readily copolymerized in almost any incorporation ratio to
the cyclic olefins.
Suitable cyclic olefins include those having at least 4 carbon
atoms and one coordination polymerizable ethylenic unsaturation site.
Such olefins include those with multicyclic structures and those having
additional hindered or masked ethylenic unsaturation not readily
available to coordination addition reactions at the catalyst coordination
site. These olefins are most usually hydrocarbyl but may include low
levels of non-carbon, heteroatoms when such are, again, hindered,
2o shielded or masked so as to not be capable of coordination at the
catalyst coordination site.
Though these olefins preferably contain only unsubstituted ring
members, substitution can be tolerated where by location or site there
is insignificant disruption of the overall crystalline configuration of the
copolymer composition made by the invention process. Preferably
substitution will be with C 1-C6 hydrocarbyl ligands not located on one
of the ethylenically bonded carbon atoms.
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Preferred cyclic olefins include cyclobutene, cyclopentene,
cyclooctene, norbornene, 5-methylnorbornene, 3-methylnorbornene,
ethylnorbornene, phenylnoibornene, dimethylnorbornene>
diethylnorbornene, dicyclopentadiene, tetracycloclododecene,
methyltetracyctododecene, and the like. ~dditianally suitable cyclic
olefins include thaw known in the art, exemplary description can be
found in WO-s4n7118 and IT.s. patents 6,2°0,393 and 5,324,80..
The preferred heteroatom-contaiini,ng, manocyclopentadienyl
Group 4 metal catalysts are in the class compromising covalently
bridged Gxoup 4 metal-containing compounds having the generic
formula:
~~,R~ d ('~ Cp,
where Rt and R~ are the same or different univalent ligands capable of
ethylene insertion or capable of abstxactioxa and replacement with a
ligand capable of ethylene insertion; d is a Group 15 heteroatom which
is eovalently bridged to Cp through a connecting group ~ and which
contains a univalent substituent sufficiently bulky to shield M from
direct approach by the cyclic olelans; and Cp is an r~,~-cyclopentadienyl
ring derivative having substitution an ring atom members such that it
is asymmetric to a line drawn between the bridging ring member and a
point on the opposite side of the ring.
R1 and R2 are identical or di~'erent and are a hydrogen atom, a
halogen atom, a C i_C lp-alkyl group, a C t_C ~,,p-alkaxy group, a Cg_
3o Clp-aryl group, a Cg.Clp-axyloxy group, a C~.C~p-all~enyl group, a
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C7-C lp-arylalkyl group, a Cg_C 10-alkylaryl group or a Cg_C 10-
arylalkenyl group.
J is the heteroatom containing ligand and includes Cg-C30
:; hydra.~arbyl ligands such as isopropyl., tert-butyl, adamantyl,
cyclododecyl, etc., as the univalent, bulky ligand. Preferably the bulky
univalent ligand will comprise a secondary, more preferably a tertiary
carbon, bound to the heteroatom so as to provide broadest bulk for
hindrance of the approach of cyclic olefins to tb a catalyst coordination
1o site. Ligands described in WO 96/00244 are particularly suitable.
The covalent bridging group T between J and Cp typically
contains Group 13-15 elements haw~.n.~ hydrogen and/or carbon or
silicon element comprising ligands. Pref~rably T comprises methylene,
15 ethylene or silylene, any of which can have alkyl, aryl, alkyaryl,
preferably C 1-C20, or silyl substituents.
Specific examples include monocyclopentadienyl catalyst
compounds having substitutions selected from known classes of ligand
20 groups readily synthesized analogously to those available in the
literature. Description is given in 5,055,438, 5,096,867, 5,264,400, and
WO 92/00333, among others. Ia particular, a preferred compound
is dimethylsilyl (3-tert-butylcyclopentadienyl) (1-adamantylamido)
hafnium dimethyl which pictorially exemplifies the class of compounds
25 suitable in this invention. Its diagram follows.
1
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Figure 1:
4
0 3 '''~~,
Hf ~~~ CH3
~CH3
5
As will be apparent from this description and diagram any alkyl
substitution of C 1 or higher carbon number, preferably C2 and higher,
most preferably Cg and higher up to Cgp, preferably up to C2p, and
most preferably up to C lp, can be used in the 3-cyclopentadienyl
position. In addition disubstituted substitution patterns can be used
where two adjacent R groups in the 3-cyclopentadienyl and 2-
cyclopentadienyl positions can be the same or different group selected
from hydrogen, C 1-C3p hydrocarbyl, preferably C2-Cep, most
preferably Cg-C lp, such as alkyl, alkenyl, aryl, alkylaryl or arylalkyl
radicals, including those structures where two adjacent R substituents
are bound together to form a further C 1-C2p substituted or
unsubstituted ring system, such as cyclohexyl, indenyl, benzyindenyl,
etc. The substituted cyclopentadienyl derivatives may have ring
positions 4 and/or 5 substituted, so long as they are substituted with
such as to preserve the asymmetric substitution pattern. Any
derivatives, such as 3-phenyl-indenyl and the like will be suitable.
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For clarity the cyclopentadienyl ring positions are to be
numbered as shown above in determining asyriimetry.
In a like manner, J may be any known amido, phosphido, etc.,
heteroatom structure having a bulky substituent in the exocyclic
position of the heteroatom as exemplified by the pictured adamantyl
group, preferably a C3-C30 hydrocarbyl substituted amido or
phosphido group.
1o Of the Group 4 tranition metals, hafnium and zirconium are
particularly suitable when low molar ratios of cyclic olefin to ethylene
are to be utilized, e.g., 3:1 to 15:1. Titanium catalysts tend to
incorporate ethylene sequences in higher amounts, thus higher levels
of cyclic olefin to ethylene will be suitable, e.g., molar ratios (cyclic
olefin:ethylene) up to 80:1, or higher, will be preferable. The higher
molar ratios can be achieved by using lower ethylene pressures and
increased cyclic olefin content in the polymerization medium. See the
process description below and in U.S. Patents 5,324,801 and 5,498,677
for further description.
A compound capable of activating the Group 4 transition metal
compound of the invention to an active catalyst state is used in the
invention process to prepare the activated catalyst. Suitable activators
include the ionizing noncoordinating anion precursor and alumoxane
activating compounds, both well known and described in the field of
metallocene catalysis.
An active, ionic catalyst composition comprising a cation of the
Group 4 transition metal compound of the invention and a
noncoordinating anion result upon reaction of the Group 4 transition
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metal compound with the ionizing noncoordinating anion precursor.
This activation reaction is suitable whether the anion precursor ionizes
the metallocene, typically by abstraction of R1 or R2, by any methods
inclusive of protonation, ammonium or carbonium salt ionization,
metal cation ionization or Lewis acid ionization. The critical feature of
this activation is cationization of the Group 4 transition metal
compound and its ionic stabilization by a resulting compatible,
noncoordinating, or weakly coordinating (included in the term
noncoordinating), anion capable of displacement by the
l0 copolymerizable monomers of the invention. See, for example, EP-A- 0
277,003, EP-A- 0 277,004, U.S. patent 5,198,401, U.S. patent
5,241,025, U.S. patent 5,387,568, WO 91/09882, WO 92/00333, WO
93/11172, and WO 94/03506 which address the use of noncoordinating
anion precursors with Group 4 transition metal catalyst compounds,
their use in polymerization processes and means of supporting them to
prepare heterogeneous catalysts. Activation by alumoxane compounds,
typically, alkyl alumoxanes, is less well defined as to its mechanism
but is none-the-less well known for use with Group 4 transition metal
compound catalysts, see for example U.S. patent 5;096,867.
The process of the invention is typically conducted in a reaction
medium conducive to interaction of the catalyst and the monomers, one
that facilitates their contact. Thus a slurry of supported catalyst in
liquid cyclic olefin may serve as the reaction medium. Similarly a
solution process using typical hydrocarbon solvents will be suitable,
preferably the solvent is one of aromatic or cycloaliphatic hydrocarbon
compounds, but linear or branched aliphatic compounds will also be
suitable. Suitable solvents thus include toluene, cyclohexane, hexane;
etc.
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The active catalyst may be supported in any manner suitable for
the reaction process chosen, particularly when a slurry process is to be
used. Numerous methods of support are known in the art for
copolymerization processes for olefins, particularly for catalysts
activated by alumoxanes, any is suitable for the invention process in
its broadest scope. See, for example, U.S. patent 5,227,440. When
using a Lewis acid ionizzng catalyst activator a particularly effective
method is that described in WO 96/04319. The support method of this
co-pending application describes the use of a Lewis acid
noncoordinating anion precursor (e.g., trisperfluorophenyl boron)
which is covalently bound to silica-containing supports through
retained hydroxy groups which as an initially formed activator complex
donates the hydroxyl hydrogens as protons for protonation of the
Group 4 transition metal compound to catalytically active cations.
The slurry or solution processes in which the contacting of
catalyst and monomers is conducted can be done under conditions
known to be suitable for the catalyst chosen. Thus, polymerization
reaction temperatures can range from below about -20 °C up to about
300 °C, and at any temperature in between. Room temperature (20
°C)
reactions are convenient but increases in activity are attainable at the
higher temperature ranges. Thus, temperatures above 60 °C are
suitable, as are those above 100 °C, or even at 120 °C and above
given
the stability of the monocyclopentadienyl catalysts of the invention.
The pressure of the polymerization is not critical as long as the
appropriate ratios of cyclic olefin to ethylene are attained. Typically
ethylene is introduced as a pressui~zed gas and can be maintained at
about 0.1 to about 15 bar, preferably 0.5 to 2.0 bar.
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The polymerization process of the invention suitably uses the
catalyst and activator in accordance with their known methods in the
known amounts and under the known conditions. Thus, preactivation
or in situ activation, and scavenging with alumoxane or alkyl
b aluminum, or combinations of them, known to those skilled in the art
will be suitable in accordance with this invention. The description of
processes in the references cited above are exemplary. Together with
the examples of the invention, one of ordinary skill in the art will
readily appreciate suitable methods.
It is believed that a catalyst structure as exemplified and
described above acts to allow ready polymerization of the bulky cyclic
olefins, but preferentially from the unhindered approaches to the metal
coordination center and in a manner dictated by the steric constraints
of the catalyst compound ligand system and both the shape of the cyclic
olefin and the position in it of the polymerizable ethylenic
unsaturation. This apparently leads to conformationally regular or
stereospecific incorporation. Additionally, the bulk of a first cyclic
olefin and the steric constraints of the catalyst ligand system during
insertion likely acts to inhibit entry into the coordination center of the
catalyst of an immediately subsequent cyclic olefin monomer. Thus
insertion of a subsequent cyclic olefin is preceded by the insertion of
ethylene which is not so sterically inhibited in entry and which acts
when inserted to remove the initially inserted cyclic olefin from the
coordination site. A subsequent cyclic olefin in turn is then not
inhibited by the inserted ethylene and can readily enter and be
inserted. A copolymer results having sequence segments that are
essentially of alternating comonomers. This copolymer has
insignificant, if any, diads comprising sequentially polymerized cyclic
olefins.
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The below exemplified catalyst was used to prepare a high
melting point, engineering polymer, of ethylene and norbornene, of the
present invention. Amounts of greater than 40 mol. % norbornene
were readily incorporated into the polymer backbone under the
reported polymerization conditions. In contrast to the catalysts of U.S.
patent 5,324,801 (see Background), which are known to be capable of
making polypropylene, the contacting of propylene with the invention
catalyst yielded essentially no measurable polypropylene polymer.
Thus it was entirely unexpected to achieve copolymerization of cyclic
monomers, since they are bulky like propylene. Similarly,
polynorbornene is known to result from the use of similar
biscyclopentadienyl catalysts but could not be produced with the
catalysts of this invention. Additionally, the inability to enchain two
i5 consecutive bulky monomers such as propylene or cyclic olefin enables
the addition of cyclic olefin monomers in broad feed ratios, to ethylene,
of from about 3:1 to 30:1 or more without sacrifice of the sought and
highly preferred substantially alternating sequence, particularly with
hafnium and zirconium compounds. Since the resulting polymer is
essentially free of cyclic-olefin diads a more defect free alternating
sequence distribution copolymer results. These copolymers can have
higher, and more predictable melting point temperatures at lower
cyclic olefin-to-ethylene ratios.
A copolymer with a melting point temperature of 235 °C was
achieved at low feed ratio (7 : 1) of norbornene to ethylene in U.S.
patent 5,324,801 . Yet at lower norbornene to ethylene ratios of less
than 6:1 the process of this invention produced copolymers of
crystalline melting points above 245 °C. See Table 2. This can be -
translated in industrial practice to a significant economic advantage in
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terms of cylic olefin conversion e~ciencies and related process
advantages.
The copolymers of the invention can be processed into polymer
compositions useful in those applications where high crystalline
melting point polymers, also known as engineering polymers, have
previously found use. Specifically, thermally stable polymer
compositions suitable for injection molding similar to polyamides and
polyesters are possible, as are the uses known for the hard, thermally
i0 stable, transparent polymer compositions of polycarbonate. Thus,
optical applications as disclosed in U.S. patent 5,324,801 are made
possible in addition to those applications suggested by the technologies
relevant to that of other engineering polymers and resins of similar
glass transition temperature or melting point. Additionally, potential
compatibilities of these polyolefin engineering polymer compositions
make it possible to prepare polymer alloys comprising the invention
product and other engineering polymers so as to prepare materials
with modified use temperatures.
2o The copolymers of the invention exhibit brittleness
characteristics of~ rigid engineering plastics. This lack of impact
toughness, or impact strength, can be improved by the inclusion of
elastomeric polymers in amounts of from 5-40 wt. %, more typically 10-
30 wt. %, and preferably 12-25 wt. %. Such elastomeric polymers can
be essentially any exhibiting compatibility with copolymers of the
invention. "Compatibility" in the sense used here means capable of
being blended with the invention copolymers, typically under melt
processing or solution conditions, and subsequently being stably
dispersed without significant problems of gross separation or
stratification.
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_ 1,~ _
Any elastomeric polymers known in the art to be suitable for
impact modification of rigid thermoplastics will be suitable,
particularly those comprising comonomers inclusive of ethylene or
cyclic alefas. Of particular importance wall be the use of rubbery or
elastomeric cyclic olefin copolymers, particularly those described in
W4 94/17113 and WO 96/11983, see also U.S. ~'at. ~lo. 5,837,787 and U.S. Pat
No. 5,763,532. Additionally, polymers based on ethylene and vinyl-aromatic
oleFms, such as styrene and alkyl-substituted styrenes will be suitable,
The following description and tables illustrate the invention
examples (~ - 3) and provide comparative examples (4 - ~) illustrating
the nonfunctional capabilities of similar _ ~;talyst,~ ~:ested ~ wring t;~e
16 development of the i vention pxacessro
Ezamples
Polymerization of ethylene) norbornene was conducted in
accordance with the following procedure under the conditions reported
in Table 1, product properties are shown in Table 2. It is notable that
only t.~,e process according to the invention in examples 1) through 3)
was capable of preparing a high crystal~iine melting paint polymer
under the selected polymerization conditions, particularly at the low
comonomer molar ratios. Under the described condi~i.ons, the bridged
_ 2s monocyclopentadienyl catalyst system of comparative example 6), not
exhibiting asymmetry in the cyclopentadienyl ring, did not produce
high melting temperature cyclic olefin copolymers. ' The glass
transition temperature (Tg) is indicative of cyclic: olefin incarporatic~-,~"
higher numbers correlate to greater incorporation. Thus cpmparati~e
3o example 5) illustrates a comparable incorporation of cyclic alehn as for
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the invention catalyst but no measurable crystalline melting point.
Similarly, biscyclopentadienyl catalyst systems exhibiting asymmetry
in one cyclopentadienyl group and a bulky substitution pattern in the
other (comparative examples 4-5) did not produce copolymers having
measurable crystalline melting point under comparable polymerization
conditions.
Ezample 1 Catalyst Activation
40.0 mg ~.-Me2Si(3-tert-BuCp)(1-Adamantyl Amido)HfMe2
i0 (prepared in accordance with the disclosure in WO 96/00244 was
weighed out under inert atmosphere and N,N-Dimethylanilinium
tetrakis-perfluorophenyl boron (DMAFi) B(pfp)3 activator was added to
give a slight molar excess of the transition metal complex. 2 mL of dry
toluene was added by pipette and the mixture allowed to stand with
i5 occasional stirring until activation was complete (10 to 20 min.). The
resulting mixture was septa sealed and ready for transfer to the
reactor via canula.
Reactor Conditions
20 0.8 liter of dry toluene was transferred to a clean, dry and N2
purged 2 liter autoclave reactor using air sensitive technique. The
solvent was stirred under a continued slow N2 purge (10 SLPM) while
the reactor was equilibrated at 60 °C. Triisobutylaluminum (TIBA)
was added as a scavenger by diluting 0.5 mL of a 1 M solution in
25 toluene with additional toluene (10 to 20 mL) and transferring to the
reactor via cannula through the purge port using standard air
sensitive technique. 106 g norbornene was added to the reactor as a
concentrated solution in toluene (86 wt.%) via cannula through the
purge port using standard air sensitive technique. The N2 purge was
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shut off simultaneously as the reactor was sealed. 15 psig (1 bar)
ethylene gas was added to the reactor until the solution was saturated.
(Molar feed ratio Norbornene: Ethylene = 5.6:1.) The ethylene
regulator and flow controller are set to maintain the 15 psig (1 bar)
ethylene pressure with a 10 SLPME replenishing flow. The reactor was
then quickly vented and the pre-activated catalyst was added to the
reactor via cannula through the purge port. The port was then sealed
and the ethylene pressure quickly returned to 15 psi (1 bar) by opening
the flow controller. The mixture was stirred at 60 °C for 74 minutes.
The reaction was quenched by rapid venting of the rector and its
contents poured into one liter of rapidly stirring acetone. The resulting
white solid polymer was washed, separated by filtration, and dried in a
vacuum oven overnight (60 °C, -30 in. Hg (-1.0 atm)). 128.4 g of
M copolymer was obtained that had a melt temperature of 247 °C, Mw
_
39,685, MWD = 1.44. Note: All weight-average molecular weight (Mw)
measurements were by gel permeation chromatography (GPC) and
were based upon a polyethylene standard. Accordingly, the Mw
reported is comparable for the examples of the invention, but not
accurate for determination of actual Mw.
Eza.mples 2 - 6
The following examples (2 - 6) were conducted in a process
similar to the one described for Example l, but with the conditions
shown in Table 1. The resulting copolymer products and the catalyst
used to prepare them are described in Table 2.
Ezample 7
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An ethylene-norbornene copolymer (A) according to the
invention was prepared with the catalyst system of Example 1 at 60°C,
but with 938 mg of catalyst, 10,960 ml toluene, and 21 psi (144.8 kPa)
ethylene pressure. An amount of 3766 g norbornene was provided to
establish a molar ratio of nonbornene to ethylene of 5.6:1. The
polymerization reaction was run for 1 hour. The yield was 1.01 kg
copolymer for an activity of 1076 g/g-h. The copolymer exhibited a Tm
of 250°C, a Tg of 112°C, Mw of 57,000 (by GPC using a PE
standard),
and a molecular weight distribution (MWD) of 2.34.
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_ 1,'8 _
cD d; .--~ .-a
m o
e et~
n
c
o
~
.
~ ~r o ~
_
c
a
a~
o
~
' .O O N ..-r
,., N
~
cflC7 Gs7 Gs7C'~
~ LL ~ m i ~- ~
,~
fJ M t eh C~
U
d N et~d~ er et;et~
'
0 0 ~ 0
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n
0
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'
' a ~ 00 00 0 0 0 0
v~
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V m ~ c ~ m
~
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Table 2 : Catalyst & Copolymer Characteristics
NB Tm Tg Mw
ExampleCatalyst Symmetry Incorp(C) (C) (PE
No. (%) Std)
(M~'~'~I
~-Me2Si(3-tert-C1 41.7 247 94 40K
1 BuCp) (1- [1_~]
Adamantyl
Amido HfMe
2 ~-Me2Si(3-tert-C 1 42.3 248 119 54K
BuCp) (1- [1.65]
Adamantyl
Amido HfMe
3 ~-Me2Si(3-tert-C1 47.0 253 121 24K
~
BuCp) [1.56]
(1-
Adamantyl
Amido ZrMe2
4 ~.-Me2Si(Me4Cp)C1 - ~5 135K
(3-MeCp) ZrMe2 [1.97]
~-Me2Si(Cp) C 1 - 134 8?K
(2MeInd) HfMe2 [1.72]
~.-Me2Si(Me4Cp)Cs 17.7 nm nm 139K
6 (t-Butylamido) [3.30]
HfMe
.~.~~ - .um, reveaiea no custlnct teature characteristic of a
glass transition temperature or melt transition.
5
An E/NB (ethylene/norbornene) elastomer (B) made in
accordance with the description in WO 94/17113 and having about 10
moles % NB, some ethylene crystallinity (Tm = 60°C, MWD = 1.83) and
Mn equal to 43,800 was also blended (20 wt %) with the stereoregular
alternating E/NB of this Example 7 to compare its ability to toughen
the brittle E/NB copolymer (A). The blending was accomplished under
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standard melt processing conditions at 250°C using a Brabender mixer
for a period of 10 min. After the removal and cooling, the resulting
blend was a rigid opaque solid with a hard shinny surface. The
compression molded film was somewhat transparent and could not be
torn by hand unless a notch was cut. The films were strong and did
not break when folded repeatedly.
Both the unmodified alternating E/NB polymer (A) and the
blend of it with the E/NB elastomer (B) were then tested under
standardized conditions for both tensile at break and % strain at
break.
Blend w/(B)
Tensile @ Break 2929 psi 6835 psi
(20,195 kPa) (47,126 kPa)
/ Strain @ Break 5.0 8.9
I claim
t
