Note: Descriptions are shown in the official language in which they were submitted.
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ETHYLENE AND/OR ALPHA-OLEFIN/VINYL OR
VINYLIDENE AROMATIC INTERPOLYMER COMPOSITIONS
The present invention relates to compositions comprising interpolymers of
vinyl
or vinylidene aromatic monomers with ethylene and/or one or more alpha-olefin
monomers. The catalyst used to prepare these interpolymers, [(4,5-methylene-
phenanthrenyl) (tert-butylamido) dimethylsilane] dimethyl titanium, has a
remarkably
high reactivity towards vinyl or vinylidene aromatic monomers. The resulting
interpolymers, contain successive vinyl or vinylidene aromatic monomer
insertions and
thus can have vinyl or vinylidene aromatic monomer incorporation in excess of
65 mole
percent.
Until recently, the copolymerization of ethylene and vinyl or vinylidene
aromatic
monomers was not a commercially viable process using the traditional Ziegler
alpha-
olefin polymerization catalysts based on Ti (III) and Ti (IV) halides. Most
earlier
attempts to prepare copolymers of vinyl aromatic monomers and alpha-olefins,
in
particular copolymers of styrene and ethylene, with such catalysts have either
failed to
obtain substantial incorporation of the vinyl aromatic monomer or else have
achieved
polymers of low molecular weight. In Polymer Bulletin, 20, 237-241(1988) there
is
disclosed a copolymer of styrene and ethylene containing 1 mole percent
styrene
incorporated therein. The reported polymer yield was 8.3 x 10~ grams of
polymer per
micromole titanium employed. However, with the advent of the metallocene based
olefin
polymerization catalysts, and in particular the constrained geometry type
catalysts, it is
now possible to copolymerize ethylene and other alpha-olefins with styrene and
other
vinyl or vinylidene aromatic monomers to provide interpolymers.
Copolymers of ethylene and styrene including materials with more than 50 mole
percent styrene incorporation have been reported using an ansa metallocene
catalyst as
disclosed by Arai, T.; Ohtsu, T.; Suzuki, S. in Macromolecular Rapid Commute.
1998,
and Polym. Prepr., 1998, 39(1), 220-221.
In addition, U.S. Patent No. 5,703,187 describes "pseudo random" ethylene
styrene interpolymers characterized by a unique monomer distribution in which
successive head-to-tail styrene monomer insertions are not observed that is no
SS diads or
SSS triads. Except for the absence of sequential head-to-tail styrene monomer
insertions,
the styrene distribution in interpolymers is still found to be well dispersed
hence the term
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"pseudo-random". A particular distinguishing feature of pseudo-random
copolymers was
the fact that all phenyl or bulky hindering groups substituted on the polymer
backbone are
separated by 2 or more methylene units. During the addition polymerization
reaction, if a
vinyl or vinylidene aromatic monomer is inserted into the growing polymer
chain, the
next monomer inserted must be ethylene or a vinyl or vinylidene aromatic
monomers
which is inserted in an inverted fashion (where inverted is taken to mean a
2,1 insertion
where a normal insertion is taken to be 1,2, however it is understood by those
skilled in
the art that the opposite can be true and would not change the_description or
properties of
the interpolymers of the present invention). After an inverted vinyl or
vinylidene
aromatic monomer insertion, the next monomer must be ethylene, as the
insertion of
another vinyl or vinylidene aromatic monomer at this point would place the
hindering
substituent closer together than the minimum separation as described above. A
consequence of these polymerization kinetics is that the catalysts used did
not
homopolymerize styrene to any appreciable extent, while a mixture of ethylene
and
styrene is rapidly polymerized and may give high styrene content (up to 50
mole percent
styrene) copolymers. A direct consequence of this monomer distribution was
that the
practical upper limit of styrene incorporation was approximately 50 mole
percent or 79
weight percent styrene.
WO 98/0999 describes the "substantially random" ethylene styrene interpolymers
which, while including the aforementioned the pseudo random interpolymers,
also
included interpolymers prepared using specific metallocene polymerization
catalysts. Use
of these specific metallocene polymerization catalysts resulted in the
formation of
interpolymers characterized by a unique monomer distribution. In this
distribution,
although most of the polymer chains are pseudo random in styrene distribution,
a small
amount of sequences involving two head-to-tail vinyl aromatic monomer
insertions
preceded and followed by at least one ethylene insertion were observed. That
is an
ethylene/styrene/styrene/ethylene tetrad, ESSE, wherein the styrene monomer
insertions
of said tetrads occur exclusively in a 1,2 manner). Thus these specific
substantially
random ethylene/styrene interpolymers contain similar peaks in the NMR
spectrum as the
pseudo random ethylene/styrene interpolymers, but also are characterized by
additional
signals with intensities appearing in the chemical shift range 43.70-44.25
ppm. As a
result of this unique monomer distribution, the upper limit of styrene
incorporation in the
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substantially random ethylene styrene interpolymers was raised to
approximately 65 mole
percent or 87.5 weight percent styrene.
We have now suprisingly discovered that that the catalyst, [(4,5-methylene-
phenanthrenyl) (tent-butylamido) dimethylsilane] dimethyl titanium, has a
remarkably
high reactivity towards vinyl or vinylidene aromatic monomers in their
polymerization
with ethylene and/or one or more alpha-olefin monomers, and results in the
preparation of
new interpolymers which include, in the case of ethylene/styrene
interpolymers, both SSS
and higher (for example SSSS, SSSSS etc) sequences. As a result of this
increased
reactivity of the catalyst, the resulting interpolymers are able to exhibit
upper limits to
their vinyl or vinylidene aromatic monomer contents in excess of 65 mol
percent.
The present invention pertains to an interpolymer comprising;
(1) from 5 to 85 mol percent ofpolymer units derived from at least one
vinyl or vinylidene aromatic monomer,
(2) from 15 to 95 mol percent of polymer units derived from at least one
of ethylene and/or a C3_zo alpha-olefin; and
(3) from 0 to 20 mol percent of polymer units derived from one or more
of ethylenically unsaturated polymerizable monomers other than those
derived from ( 1 ) and (2); and
wherein said interpolymer contains detectable vinyl or vinylidene aromatic
monomer triads.
All references herein to elements or metals belonging to a certain Group refer
to
the Periodic Table of the Elements published and copyrighted by CRC Press,
Inc., 1989.
Also any reference to the Group or Groups shall be to the Group or Groups as
reflected in
this Periodic Table of the Elements using the IUPAC system for numbering
groups.
Any numerical values recited herein include all values from the lower value to
the
upper value in increments of one unit provided that there is a separation of
at least 2 units
between any lower value and any higher value. As an example, if it is stated
that the
amount of a component or a value of a process variable such as, for example,
temperature,
pressure, time is, for example, from 1 to 90, preferably from 20 to 80, more
preferably
from 30 to 70, it is intended that values such as 15 to 85, 22 to 68, 43 to
51, 30 to 32 etc.
are expressly enumerated in this specification. For values which are less than
one, one
unit is considered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate. These are
only
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examples of what is specifically intended and all possible combinations of
numerical
values between the lowest value and the highest value enumerated are to be
considered to
be expressly stated in this application in a similar manner.
The term "interpolymer" is used herein to indicate a polymer wherein at least
two
different monomers are polymerized to make the interpolymer. This includes
copolymers, terpolymers, etc.
The term "detectable vinyl or vinylidene aromatic monomer triads" is used
herein
to indicate a sequence of three successive vinyl or vinylidene aromatic
insertions in the
interpolymer. In the case of an ethylene/styrene interpolymer this would
correspond to an
-SSS- triad. When any atactic polystyrene impurity is separated out from the
polymer,
these triads are detectable by the presence of a peak in the'3C NMR spectrum
which
occurs at a chemical shift corresponding to the methine carbons in the polymer
backbone
of an ethylene/styrene interpolymer at 44.6 ppm (ESSSE) Such triads may also
be a part
of a longer sequence of vinyl or vinylidene aromatic insertions insertions
such as SSSS
tetrads, SSSSS pentads. Additional peaks corresponding to the following
insertions may
also be present in the interpolymers; 46.0 ppm (ESE), 43.75 (ESSE), and 41.6
ppm (>3
successive S insertions). It is understood by one skilled in the art that for
such insertions
involving a vinyl or vinylidene aromatic monomer other than styrene, and an
alpha-olefin
other than ethylene, then the interpolymer will give rise to similar'3C NMR
peaks but
with slightly different chemical shifts.
The interpolymers of the present invention are prepared using the catalyst ,
[(4,5-
methylene-phenanthrenyl) (tert-butylamido) dimethylsilane]dimethyl titanium.
CH3 CH3
CH3
CH3~Si/ \ , CH3
CH3~ / ~ CH
3
OY
We have surprisingly discovered that that this catalyst has a remarkably high
reactivity towards vinyl or vinylidene aromatic monomers in their
polymerization with
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ethylene and/or one or more alpha-olefin monomers. This results in the
preparation of
new interpolymers which include, in the case of ethylene/styrene
interpolymers, both SSS
and higher (for example SSSS, SSSSS etc) sequences. As a result of the
increased
reactivity of the catalyst, the resulting interpolymers are able to exhibit
upper limits to
vinyl or vinylidene aromatic monomer contents in excess of 65 mol percent.
One method of preparation of the interpolymers of the present invention
includes
polymerizing a mixture of polymerizable monomers in the presence of [(4,5-
methylene-
phenanthrenyl) (tert-butylamido) dimethylsilane]dimethyl titanium and a
suitable
activating compound. Using this catalyst, the interpolymers of the present
invention can
be prepared by the processes described in EP-A-0,416,815 by James C. Stevens
et al. and
US Patent No. 5,703,187 by Francis J. Timmers, both of which are incorporated
herein by
reference in their entirety. Preferred operating conditions for such
polymerization
reactions are pressures from atmospheric up to 3000 atmospheres and
temperatures from -
50°C to 200°C. Polymerizations and unreacted monomer removal at
temperatures above
the autopolymerization temperature of the respective monomers may result in
formation
of some amounts of homopolymer polymerization products resulting from free
radical
polymerization. While preparing the interpolymers of the present invention, an
amount
of atactic vinyl or vinylidene aromatic homopolymer may be formed due to
homopolymerization of the vinyl aromatic monomer at elevated temperatures. The
presence of vinyl aromatic homopolymer is in general not detrimental for the
purposes of
the present invention and can be tolerated. The vinyl aromatic homopolymer may
be
separated from the interpolymer, if desired, by extraction techniques such as
liquid
chromatography or selective precipitation from solution with a non solvent for
either the
interpolymer or the vinyl or vinylidene aromatic homopolymer.
The interpolymers of the present invention include interpolymers prepared by
polymerizing i) ethylene and/or one or more alpha-olefin monomers and ii) one
or more
vinyl or vinylidene aromatic monomers and optionally iii) other polymerizable
ethylenically unsaturated monomer(s).
Suitable alpha-olefins include for example, alpha-olefins containing from 3 to
20,
preferably from 3 to 12, more preferably from 3 to 8 carbon atoms.
Particularly suitable
are ethylene, propylene,.butene-1, 4-methyl-1-pentene, hexene-1 or octene-1 or
ethylene
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in combination with one or more of propylene, butene-1, 4-methyl-1-pentene,
hexene-1 or
octene-1. These alpha-olefins do not contain an aromatic moiety.
Other optional polymerizable ethylenically unsaturated monomers) include
norbornene and C,_,o alkyl or C6_,o aryl substituted norbornenes, with an
exemplary
interpolymers being ethylene/styrene/norbornene and
ethylene/styrene/ethylidene
norbornene.
Suitable vinyl or vinylidene aromatic monomers, which can be employed to
prepare the interpolymers, include, for example, those represented by the
following
formula:
Ar
( ~ H2)n
Rl - C = C(R2)2
wherein R' is selected from the group of radicals consisting of hydrogen and
alkyl
radicals containing from 1 to 4 carbon atoms, preferably hydrogen or methyl;
each R' is
independently selected from the group of radicals consisting of hydrogen and
alkyl
radicals containing from 1 to 4 carbon atoms, preferably hydrogen or methyl;
Ar is a
phenyl group or a phenyl group substituted with from 1 to 5 substituents
selected from the
group consisting of halo, C,_4-alkyl, and C,~-haloalkyl; and n has a value
from zero to 4,
preferably from zero to 2, most preferably zero. Exemplary vinyl aromatic
monomers
include styrene, vinyl toluene, alpha-methylstyrene, t-butyl styrene,
chlorostyrene,
including all isomers of these compounds. Particularly suitable such monomers
include
styrene and lower alkyl- or halogen-substituted derivatives thereof. Preferred
monomers
include styrene, alpha-methyl styrene, the lower alkyl- (C, - C4) or phenyl-
ring substituted
derivatives of styrene, such as for example, ortho-, meta-, and para-
methylstyrene, the
ring halogenated styrenes, para-vinyl toluene or mixtures thereof. A more
preferred vinyl
aromatic monomer is styrene.
The resulting interpolymers may be modified by typical grafting,
hydrogenation,
functionalizing, or other reactions well known to those skilled in the art.
The polymers
may be readily sulfonated, using processes described in WO 99/20691, the
entire contents
of which are herein incorporated by reference, chlorinated or otherwise
functionalized, as
described in copending L1S Application No. 09/244,921 filed on February 42",
1999 by R.
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E. Drumright et al., the entire contents of which are herein incorporated by
reference. The
compositions of the present invention may also be modified by various cross-
linking
processes. These include, but are not limited to peroxide-, silane-, sulfur-,
radiation-, or
azide-based cure systems. A full description of the various cross-linking
technologies is
described in U.S. Patent 5,869,591 and 5977,271, the entire contents of both
of which are
herein incorporated by reference. Dual cure systems, which use a combination
of heat,
moisture cure, and radiation steps, may be effectively employed. For instance,
it may be
desirable to employ peroxide crosslinking agents in conjunction with silane
crosslinking
agents, peroxide crosslinking agents in conjunction with radiation, sulfur-
containing
crosslinking agents in conjunction with silane crosslinking agents, etc. Dual
cure systems
are disclosed and claimed in U. S. Patent 5,911,940, the entire contents of
which is
incorporated herein by reference.
Additives such as antioxidants (for example, hindered phenols such as, for
example, Irganox~ 1010 a registered trademark of Ciba Geigy), phosphites (for
example,
Irgafos~ 168 a registered trademark of Ciba Geigy), U.V. stabilizers, cling
additives (for
example, polyisobutylene), slip agents (such as erucamide and/or stearamide),
antiblock
additives, colorants, pigments, tackifiers, flame retardants, coupling agents,
fillers,
plastcizers can also be included in the compositions of the present invention.
Also included as a potential component in the compositions of the present
invention are various organic and inorganic fillers. Representative examples
of such
fillers include organic and inorganic fibers such as those made from asbestos,
boron,
graphite, ceramic, glass, metals (such as stainless steel) or polymers (such
as aramid
fibers) talc, carbon black, carbon fibers, calcium carbonate, alumina
trihydrate, glass
fibers, marble dust, cement dust, clay, feldspar, silica or glass, fumed
silica, alumina,
magnesium oxide, magnesium hydroxide, antimony oxide, zinc oxide, barium
sulfate,
aluminum silicate, ammonium polyphosphate, calcium silicate, titanium dioxide,
titanates, aluminum nitride, B203, nickel powder or chalk.
Other representative organic or inorganic fiber or mineral fillers include
carbonates such as barium, calcium or magnesium carbonate; borates such as
magnesium
or zinc borate, fluorides such as calcium or sodium aluminum fluoride;
hydroxides such
as aluminum hydroxide; metals such as aluminum, bronze, lead or zinc; oxides
such as
aluminum, antimony, magnesium or zinc oxide, or silicon or titanium dioxide;
silicates
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such as asbestos, mica, clay (kaolin or calcined kaolin), calcium silicate,
feldspar, glass
(ground or flaked glass or hollow glass spheres or microspheres or beads,
whiskers or
filaments), nepheline, perlite, pyrophyllite, talc or wollastonite; sulfates
such as barium or
calcium sulfate; metal sulfides; cellulose, in forms such as wood or shell
flour; calcium
terephthalate; and liquid crystals. Mixtures of more than one such filler may
be used as
well.
The fillers may also be used in conjunction with a coupling agent and/or
initiator
selected from organic peroxides, silanes, titanates, zirconates,_multi-
functional vinyl
compounds, organic azides, and mixtures thereof.
Other additives include the hindered amine stabilizers. Such stabilizers
include
hindered triazines such as substituted triazines and reaction products of
triazines. Suitable
reaction products include the reaction product of triazine with, for example,
diamines and/
or cycloaliphatic compounds such as cyclohexane. A particularly suitable
hindered amine
stabilizer includes the reaction product of 1, 3-propanediamine, N,N"-1,2-
ethanediylbis-,
cyclohexane and peroxidized N-butyl-2,2,6,6-tetramethyl-4-piperidinamine-2,4,6-
trichloro-1,3,5-triazine which ismade commercially by Ciba-Geigy and has the
name
"CG-116 having CAS Reg No. : 191680-81-6.
These additives are employed in functionally equivalent amounts known to those
skilled in the art. For example, the amount of antioxidant employed is that
amount which
prevents the polymer or polymer blend from undergoing oxidation at the
temperatures
and environment employed during storage and ultimate use of the polymers. Such
amount of antioxidants is usually in the range of from 0.01 to 10, preferably
from 0.05 to
5, more preferably from 0.1 to 2 percent by weight based upon the weight of
the polymer
or polymer blend. Similarly, the amounts of any of the other enumerated
additives are the
functionally equivalent amounts such as the amount to render the polymer or
polymer
blend antiblocking, to produce the desired result, to provide the desired
color from the
colorant or pigment. Such additives can suitably be employed in the range of
from 0.05
to 50, preferably from 0.1 to 35, more preferably from 0.2 to 20 percent by
weight based
upon the weight of the interpolymer. Fillers may suitably be employed in the
range 1-90
wt.percent.
The polymers of the present invention can be blended with additional polymers
including but not limited to; other interpolymers of different molecular
weight and/or
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vinyl or vinylidene aromatic monomer content, substantially random
interpolymers vinyl
and vinylidene halide polymers including but not limited to polyvinyl
chloride) and
poly(vinylidene chloride), polyethylene, and other polyolefins including but
not limited to
LDPE, and HDPE, PP, homogeneous ethylene/alpha-olefin copolymers produced by
metallocene catalysts, including but not limited to the substantially linear
ethylene/alpha-
olefin copolymers and heterogeneous and heterogeneous ethylene/alpha-olefin
copolymers produced by Ziegler catalysts; styrenic polymers including but not
limited to
polystyrene, SBS copolymers, polyethers, polycarbonates, polyanilines,
asphalt, or any
combinations thereof.
The interpolymers of the present invention, or blends thereof, can be
fabricated
into various forms including but not limited to films, fibers, foams, sheets,
injection
molded articles, membranes, injection-blow molded articles and extruded
profiles, and
emulsions. Applications for the interpolymers of the present invention, or
blends thereof,
include, but are not limited to, ignition resistant articles, pressure
sensitive filmstock,
coating compositions or paints, floor, ceiling and wall coverings, carpet
backing, barriers,
gaskets, caps and closures, and, with the addition of conductive additives
such as carbon
black, various conductive applications including electrical devices, conductor
shields,
insulation shields, and other wire and cable applications. Other applications
include as
compatibilizers in blends of polystyrene and ethylene and/or alpha-olefin homo-
and
copolymers. Also included are applications for the sulfonated derivatives
including their
use in fuel cell membranes, water absorbent applications and HVAC equipment.
Determining the composition of the ethylene/styrene interpolymers of the
present
invention can be ambiguous using NMR methods of analysis. This ambiguity
arises from
the fact that the styrene triads and higher order styrene insertions have
peaks in both the
'H and'3C spectra that can not be distinguished from peaks of the ubiquitous
amorphous
atactic polystyrene homopolymer (aPS) which is present in small amounts in the
interpolymers. However use of a liquid chromatography (LC) method using
gradient
solvent polarity allows separation of the interpolymer from the aPS, and the
retention
time of the interpolymer peak is indicative of its styrene content.
The interpolymer compositions of the present invention comprise from 5 to 85,
preferably from 20 to 85, more preferably from 50 to 85 mole percent of at
least one vinyl
or vinyl or vinylidene aromatic monomer and from 15 to 95, preferably from 15
to 80,
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more preferably from 15 to 50 mole percent of ethylene and/or at least one
aliphatic
alpha-olefin having from 3 to 20 carbon atoms.
The melt index (I2) of the interpolymer of the present invention is greater
than
0.05, preferably of from 0.5 to 200, more preferably of from 0.5 to 100 g/10
min.
The molecular weight distribution (Mw/Mn) of the interpolymers of the present
invention is from 1.5 to 20, preferably of from 1.8 to 10, more preferably of
from 2 to 5.
The interpolymer compositions of the present invention contain detectable
vinyl
aromatic monomer triads. In the case of an ethylene/styrene interpolymer this
would
correspond to an -SSS- triad. Such triads may also be a part of a longer
sequence of vinyl
or vinylidene aromatic insertions insertions such as SSSS tetrads, SSSSS
pentads. When
any atactic polystyrene impurity is separated out from the polymer, these
triads are
detectable by the presence of a peak in the'3C NMR which occurs at a chemical
shift
corresponding to the methine carbons in the polymer backbone of an
ethylene/styrene
interpolymer at 44.6 ppm (ESSSE).
The following examples are illustrative of the invention, but are not to be
construed as to limiting the scope thereof in any manner.
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EXAMPLES
Test Methods
The molecular weight of the polymer compositions of the present invention is
conveniently indicated using Gel Permeation Chromatography using both UV and
Refractive Index detectors.
In order to determine the '3C NMR chemical shifts of the interpolymers of the
present invention, the following procedures and conditions are employed. A
five to ten
weight percent polymer solution is prepared in a mixture consisting of 50
volume percent
1,1,2,2-tetrachloroethane-d2 and 50 volume percent 0.10 molar chromium
tris(acetylacetonate) in 1,2,4-trichlorobenzene. NMR spectra are acquired at
130°C using
an inverse gated decoupling sequence, a 90°-pulse width and a pulse
delay of five seconds
or more. The spectra are referenced to the isolated methylene signal of the
polymer
assigned at 30.000 ppm.
Materials Testing
Polymer samples were formed into the shapes required for physical property
determination by compression molding at 150°C using a ten minute
preheat, 3 minute
compression at 10000 pounds force, and immediate cool down.
Differential Scanning Calorimetry (DSC) analysis of this polymer was performed
under a nitrogen atmosphere at a heating rate of 5°C/minute using a
DuPont Instruments
910 Differential Scanning Calorimeter. All samples were taken through two
heating
cycles (to remove the effects of previous heat history) and data are reported
for the second
scan in all cases.
Micro-tensile testing was performed using compression molded micro-tensile
bars
as per ASTM D638 testing protocol. The samples were pulled using an Instron
4507
Series instrument at a cross-head speed of 0.1 inches/minute and a 224.8 lbf
load cell at
room temperature.
Plain-strain fracture toughness, compact tension single-edge notch geometry
samples were compression molded into 1" by 1" by 1/8" squares. These squares
were
machined to provide a side notch and holes for attachment to the testing
apparatus. A pre-
crack was formed in each sample by cooling with liquid nitrogen and cracking
with a
razor blade and hammex. Fracture toughness testing was performed using an
Instron 8501
instrument at a cross-head speed of 0.02 in/min with a 224.8 lbf load cell.
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Dynamic mechanical spectroscopy was performed on a rectangular bar, which was
compression molded at 100°C. Temperature sweeps ranging from -
100°C to 150°C were
performed at a set frequency of 1 rad/sec with an auto-strain function set by
the DMS
instrument.
Density was measured using a helium pycnometer. Rockwell hardness was
assessed using ASTM D785-93.
L.C. Analysis.
Between 0.100 and 0.102 grams of polymer were weighed into a 30 ml vial. 10
ml of THF was added. The vial was capped and placed on a heated shaker so as
to
dissolve the sample. The temperature of the heated shaker was 65° C.
After dissolution,
about 1 ml of the solution was transferred to an HP 1090 LC auto-injector
vial. A
Hewlett-Packard 1090 LC (serial number 2541A00700) with a diode array detector
was
used for the collection of all chromatographic data. Signals were collected at
254 nm and
400 nm. The chromatographic data were processed using Grams386 and Excel
software.
Two columns were used to determine the styrene contents of the resins by
liquid
chromatography. Use of either column initially involved determination of the
atactic
polystyrene content (which peak was clearly discernible). This value was then
subtracted
from the total styrene content of the sample as determined by 13C N.M.R to
give the
wtpercent copolymerized styrene. A calibration curve of copolymerized styrene
v.
retention time (at the 50'" percentile of the chromatogram peak) was then
constructed and
the resulting fit was then applied to all new samples. This analysis was
performed using
two types of column.
The first of these was a C 18 column was obtained from Alltech: Spherisorb ODS
II 5 micron, 250 x 4.60 mm. There was a guard column on the C18 column. It was
an RP
8.5 micron. Below are the instrumental conditions used on the HP 1090 with the
C 18
column).
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Solvent A = AcetonitrileAt 24.00 Flow = 1.000
Solvent B = THF At 24.00 percent B =
100.0, C =
Solvent C = 2-Propanol At 25.00 Flow = 1.000
Store Flow 1; At 25.00 percent B =
1.0, C = 0.0
Stop Time=30.00 At 30.00 Flow = 1.000
Post Time = 0.00 At 30.00 percent B =
1.0, C = 0.0
SDS-Config A=1,B=1,C=1
Max Press = 400 Stop time = system
Min Press = 8 Post time = 1.00 minute
B=1.O,C=0.0 Auto balance = on
Injection Volume=10.0 Peak width = 0.100
1
Oven Temp = 50.0 Spectra Range=240, 600,
2
At 1.00 Flow =1.000 ml/minStore Spectra = peak
At 1.00 percent B=1.0,C=0.0Threshold=1.000
At 20.00 Flow =1.000 Signal A=254, 4, 550,
20
At 20.00 percent B=100.0,C=0.0Signal B=400, 4, 550,
20
The second and best column of the two was a nitro column obtained from
Phenomenex: Nucleosil 5 N02 250 x 4.60 mm, 5 micron, serial number 243745.
There
was a guard column on the nitro column. It was a Phenomenex Nucleosil 5 N02 30
x 4.6
mm, 5 micron 100 angstrom, serial number 2437476. Below are the instrumental
conditions used on the HP 1090 with the Nitro2 method (nitro column).
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Solvent A = Hexanes At 20.00 Flow=1.000
Solvent B = THF At 20.00 percent B=70.O,C=0.0
Solvent C = 2-propanol At 23.00 Flow=1.000
Store A 1; At 23.00 percent B=70.O,C=0.0
Store B 1; At 24.00 Flow=1.000
Store C 1; At 24.00 percent B=3.O,C=0.0
Store Flow 1; At 30.00 Flow=1.000
Store Temp l; At 30.00 percent B=3.O,C=0.0
Stop Time=30.00 minutes
Post Time=0.00 minutes
SDS-Config A=1, B=1, Stop Time = System
C=1
Flow=1.000 ml/min Post Time=1.00 minute
Max Press=400 bar Auto Balance = on
Min Press=8 Peakwidth=0.100
percent B=3.O,C=0.0 Spectra Range=240, 600,
2
Inj volum=10.0 1 Store Spectra = peak
Oven Temp=30.0 c Threshold=1.000
At 1.00 Flow=1.000 Signal A=254, 4, 550,
20
At 1.00 percent B=3.O,C=0.0Signal B=400, 4, 550,
20
The regression equation used to determine the styrene content on this column
was:
[sty] wtpercent = -84.89 + 10.98 * retention time (mins)
Preparation of the Examples 1 - 6 of the Inter~olymers of the Present
Invention.
1~ Preparation of Catalyst
General
Syntheses and manipulations were carried out in an inert atmosphere (argon)
glove box. Solvents were purchased from Aldrich. Liquid reagents and solvents
were
first saturated with nitrogen and then dried by passage through activated
alumina prior to
use as disclosed by Pangborn, A.B.; Giardello, M.A.; Grubbs, R.H.; Rosen,
R.K.;
Timmers, F.J. in Organometallics, 1996, I5, 1518- 1520 . Deuterated benzene
was dried
over sodium/potassium alloy and filtered prior to use. Methylene phenanthrene
was
purchased from Lancaster. NMR spectra of ligands and metal complexes were
recorded
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on a Varian 300 MHz NMR spectrometer at ambient conditions. '''C NMR spectra
of the
copolymers were recorded on a Bruker 600 MHz spectrometer.
Synthesis of Lithium Methylenephenanthrenide
To 4,5-methylenephenanthrene (0.485 g, 2.55 mmol) in 50 mL of hexanes was
added 1.6 M n-BuLi in hexanes ( 1.75 mL, 2.80 mmol). After one day of stirring
at
ambient conditions the solution appeared darker orange and a small amount of
orange
precipitated had formed. After 14 days much more precipitate had formed. This
was
isolated by decanting the supernatant from the solid which stuck to the inside
walls of the
flask. After drying under reduced pressure, 0.430 g were isolated (86percent
yield).
Volatile materials were removed from the supernatant to give an orange solid.
Proton
NMR analysis of this material showed it to be the starting
methylenephenanthrene.
Synthesis of (4,5-methylenephenanthrenyl)(tert-butylamino)dimethylsilane
To (tert-butylamino)dimethylsilyl chloride (0.436 g, 2.63 mmol) in 30 mL THF
was added a cherry red solution of lithium methylenephenanthrenide (0.430 g,
2.19
mmol) in 20 mL THF. The solution was allowed to stir at ambient temperature
overnight.
The volatile materials were removed under reduced pressure. The solid residue
was
slurried in 10 mL hexanes and the volatile materials were removed under
reduced
pressure. The solid residue was extracted twice with a total of 30 mL hexanes.
The
extracts were filtered and the volatile materials were removed from the
combined filtrates
under reduced pressure to give 0.690 g (99percent yield) of an orange oil.
The'H NMR
spectrum was consistent with the desired product.
Synthesis of [(4,5-methylenephenanthrenyl)(tert-
butylamido)dimethylsilane]titanium
bis(dimethylamide)
A solution of the titanium tetrakis amide (0.484 g, 2.16 mmol) and (4,5-
methylenephenanthrenyl)(tert-butylamino)dimethylsilane (0.690 g, 2.16 mmol) in
50 mL
n-octane was heated and stirred at reflux. The course of the reaction was
monitored by'H
NMR spectroscopy by removing a small aliquot of the solution, removing the
volatile
materials under reduced pressure, and analyzing the residue in C6D6. Proton
NMR
analysis showed clean conversion to the desired product (for example SSpercent
conversion after ca. 48 hours reflux.) Several drops of titanium tetrakis
amide were added
periodically. After seven days at reflux, the reaction appeared not to be
progressing past
82percent conversion. The volatile materials were removed from the cooled
mixture
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under reduced pressure. The residue was dissolved in 20 mL of hexanes and the
resulting
mixture was filtered. The volatile materials were removed from the filtrate
under reduced
pressure to give a dark powder (0.950 g). Proton NMR analysis of the product
showed it
to be a mixture of the desired product and the starting ligand, 82/18 mole
percent,
respectively (87 weight percent of the desired product).
Synthesis of [(4,5-methylenephenanthrenyl)(tert-
butylamido)dimethylsilane]titanium
dichloride
To the bis(amide)/ligand mixture isolated above (0.83.g, 1.83 mmol of the
bis(amide)) issolved in 40 mL hexanes was added trimethylsilyl chloride (1.33
mL, 10.5
mmol). The solution was stirred at reflux for six hours. A small aliquot of
the cooled
solution was removed and the volatile materials were removed under reduced
pressure.
The residue was dissolved in C6D6 and analyzed by'H NMR spectroscopy. The
spectrum
showed very clean conversion to the monochloride-monoamide intermediate. An
additional 1.3 mL of trimethylsilyl chloride was added and the sealed vessel
was stirred at
ambient temperature for eight days. The solution was then heated to reflux for
six hours.
The cooled solution was placed in the glove box freezer (-25°C). The
solids that formed
were collected on a glass frit by vacuum filtration. The solid residue was
washed once
with cold hexanes (ca. 10 mL) and the solid was then dried under reduced
pressure to give
0.516 g (65percent yield). Proton NMR analysis showed the material was
consistent with
very clean desired product.
Synthesis of [(4,5-methylenephenanthrenyl)(tertbutylamido)-dimethylsilane]
dimethyltitanium
To the dichloride (0.516 g, 1.18 mmol) in 30 mL of THF was added 3.0 M
methylmagnesium chloride (0.87 mL, 2.6 mmol) which resulted in an immediate
color
change. After standing overnight, the volatile materials were removed under
reduced
pressure. The solid residue was slurried in hexanes and the volatile materials
were
removed under reduced pressure. The residue was extracted several times with
hexanes.
The extracts were filtered and the volatile materials were removed from the
combined
filtrates under reduced pressure to give a bright orange powder, 0.392 g.
Proton and'3C
NMR analysis in C6D6 shows that the desired product was isolated as a 1 to 1
adduct with
THF. Assuming a molecular weight was 467.6 g/mol, the isolated yield was 71
percent.
The THF adduct (0.345 g) was dissolved in 50 mL toluene and heated at reflux
for six
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hours. A color change from orange to brown-yellow was observed. The volatile
materials
were removed under reduced pressure. Proton NMR analysis of the residue showed
clean
conversion to a new compound.
2.wmerization
All transfers of solvents and solutions described below were accomplished
using a
gaseous pad of dry, purified nitrogen or argon. Gaseous feeds to the reactor
were purified
by passage through columns of A-204 alumina and QS reactant. Alumina was
previously
activated at 375°C with nitrogen and QS reactant was activated at
200°C with Spercent
hydrogen in nitrogen. Manipulations of catalyst and cocatalyst (tris
pentafluorophenyl
borane) were carried out in an inert atmosphere glove box.
The semi-batch reactor polymerization was conducted in a two liter Parr
reactor
with an electrical heating jacket, internal serpentine coil for cooling, and a
bottom drain
valve. Pressures, temperatures and block valves were computer monitored and
controlled.
Isopar E and styrene were measured in a solvent shot tank fitted to a balance.
The
resulting solution was then added to the reactor from the solvent shot tank.
The contents
of the reactor were stirred at 1200 rpm. Hydrogen was added by differential
expansion
(ca. 50 psi) from a 75 ml shot tank initially at 300 psig. The contents of the
reactor were
then heated to the desired run temperature (90°C) under the desired
ethylene pressure.
The catalyst, [(4,5-methylenephenanthrenyl)(tert-butylamido)dimethylsilane)-
dimethyltitanium and cocatalyst, tris(pentafluorophenyl)borane, were combined
in the
glove box (as 0.0050 M solutions in toluene)and transferred from the glove box
to the
catalyst shot tank through 1/16 in (0.16 cm) tubing using toluene to aid in
the transfer.
The catalyst tank was then pressurized using nitrogen. After the contents of
the reactor
had stabilized at the desired run temperature, the catalyst solution was
injected into the
reactor via a dip tube. The temperature was maintained by allowing cold glycol
to pass
through the internal cooling coils. The reaction was allowed to proceed for
the desired
time with ethylene provided on demand. Additional injections of catalyst were
prepared
and added in the same manner during the course of the run.
The contents of the reactor were then expelled into a 4 liter nitrogen purged
vessel
and quenched with isopropyl alcohol and 100 mg of Irganox 1010 in toluene was
added
as an antioxidant. Volatile materials were removed from the polymers in a
vacuum oven
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at 140°C overnight and cooled to 50°C prior to removal from the
oven. Reactor
conditions and polymerization data were given in Table I.
Table I: Reactor Conditions/Run Data
Examp Catalyst CocatalStyren IsoparTEthyleTime Yiel
1e ( mol) yst a (g) M E ne (min) d
# (g)
( mol) (psig) (g)
1 18.0 18.0 229 538 S00 30 3.9
2 18.0 18.0 455 358 500 39 56.
2
3 16.0 16.0 457 360 200 30 51.
8
4 18.0 27.0 602 - 200 30 56.
0
18.0 27.0 602 - 100 30 34:
2
6 18.0 27.0 602 - 50 30 22.
4
5 Polymer Characterization
An LC method using gradient solvent polarity was used to separate the
interpolymer from
the aPS and the retention time of the interpolymer peak was indicative of its
styrene content.
Shown in Table II were composition, apparent molecular weight (polystyrene
standards) and
density data for the polymers reported herein.
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Table II: Polymer Composition, Molecular Weight and Density Data
ExamplMole percentWt percentperce Mw Mn Mw/Mn Density
a # Styrene Styrene t aPS (g/cm3)
1 24.7 54.9 <1 -- -- -- 0.9979
2 45.8 75.9 <1 -- -- -- 1.028
3 53.8" 81.2" (78.1B)1.7 660,000287,0002.30 1.028
(49.0)B
4 56.6" 82.9" (80.4B10.3 684,000198,0003.45 1.031
(52.5)B )
63.5~ 86.6" (84.9B)18.3 583,000133,0004.38 1.037
(60.2)B
6 74.6A 91.6A (91.0B)33.5 541,00098,500 5.49 1.038
(73.1)B
A From LC data with nitro column.
B From LC data with C 18 column.
5 C From proton NMR data.
With the information that these copolymers contained aPS, the SSS triad peaks
in their
'3C NMR spectra could be assigned. A very small EEE triad peak indicated that
the
interpolymers had very few and short ethylene sequences.
These materials all display either low levels of crystallinity, or were
amorphous. As a
result, the density of these polymers increases with increasing styrene
content and approaches
1.06 g/cc, the density of aPS.
The molecular weight data shows that the catalyst can produce high molecular
weight
polymers. Since a dual detector was used in the GPC analysis, it was possible
to examine the
ratio of refractive index divided by UV response across the molecular weight
range. This ratio
was found not to change much indicating that the composition was relatively
uniform across the
entire molecular weight range; a slight increase in the styrene content at
very low molecular
weights was seen in all of the samples. This was consistent with the presence
of aPS in these
materials.
Materials Properties
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The thermal transition data as determined by DSC were given in Table III.
Table III Thermal Transitions (DSC)
ExamplStyrene Styrene Tg; Tm,C Hf, J/g
a # (mol percent)(weight C
percent)
1 24.7 54.9 31.9 123 26.5
2 45.8 75.9 32.5 119 1.7
3 53.8" (49.0)B81.2A (78.139.7 - -- --
B )
4 56.6~ (52.5)B82.9" (80.4B44.2 -- --
)
63.5A (60.2)B86.6A (84.9B)55.5 -- --
6 74.6" (73.191.6" (91.0B)70.3 -- --
)B
A From LC data with nitro column.
B From LC data with C18 column.
5 C From proton NMR data.
As expected, the Tg of these materials was found to increase with increasing
styrene
content. The last two entries, which were well beyond the composition range of
earlier pseudo
random materials, show that the Tg rapidly approaches that of aPS (ca.
100°C) as the styrene
content approaches near 100 percent. It should also be noted that none of the
materials showed a
pronounced Tg due to aPS homopolymer. The LC data, however, show aPS in the
isolated
materials. The polymer with the highest crystallinity (the lowest styrene
content 55 wt percent S)
displayed a peak melting temperature near 120°C and a Tg near
32°C.
Micro-tensile testing and fracture toughness testing was performed to assess
the
mechanical properties of these materials, Table IV. Short term tensile
analysis showed a
relatively glassy response with a high modulus at low tensile stress and a
relatively linear
stress/strain relationship for all of the materials up to about 2percent
strain. The Young's
modulus for all of these materials was in the range of 350,000-430,000 psi
(2.4-3 GPa). All of the
materials underwent a ductile yield at relatively low strains, with the yield
strain moving steadily
to lower elongation with increasing styrene content. All of the polymers
exhibited slight drawing
past the yield point up to ultimate failure.
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Table IV Microtensile, Fracture Toughness and Hardness Data
Ex Wt Yield percentBreak percentYoung's ardnessa
#
percentStressStrainStress StrainModulus
psi
Styrene(psi) at (psi) at (sd)
Yield
Break
1 54.9 - - - - - 56
2 75.9 - - - - - 86
3 78.1 6,870 2.7 6,720 3.1 -347,000 86
(33,000)
4 80.4 6,950 2.3 6,550 2.9 365,000 89
(48,000)
84.9 7,130 2.1 6,540 4.9 434,000 100
(36,000)
6 91.0 6,320 1.9 6,250 2.5 376,000 99
(68,000)
aRockwell scale
Fracture toughness was measured using compact tension geometry samples. These
experiments were designed to quantify the polymer's resistance to initiation
and propagation of
the crack with respect to an applied load. The test was performed on a
compression-molded
square of the polymer, which was notched, and a razor blade was used to
produce a crack at the V
of the notch. A tensile load was then applied to the sample in plane stress;
the specimen prepared
was ideally thick enough to prevent twisting out the plane of the applied
load. The resultant
relationship between load and displacement allows for determination of the
instantaneous stress
required to propagate the crack, known as the stress intensity factor Klc. It
was also useful to
define the energy required to extend the crack over a given unit area; this
quantity was denoted
Glc, (the fracture energy or critical strain-energy release rate) and it
related to Klc by equation 1:
Gm _ (Knz/E)(1-2) (1)
where E was Young's modulus and is Poisson's ratio. Larger values of Klc and
Glc mean
increased fracture toughness.
Fracture toughness measurements did not show meaningful differences from
sample to
sample for the materials, which were tested. Table V gives the critical stress
intensity factor
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(K1 C) values for the four samples with the highest styrene content, and data
obtained under the
same test conditions for a high molecular weight free radically polymerized
polystyrene
homopolymer. The copolymers show considerably higher K1C and G1C values, and
the load to
yield and to break were considerably higher for the copolymers than for
polystyrene
homopolymer.
The improved toughness of these materials with respect to polystyrene may
arise from the
ability of the ethylene units incorporated to induce a more ductile response
to applied stress on
the time scale of the fracture test.
Table V Fracture Toughness Data for ES Copolymers
Ex # Wt K,~ Maximum Yield Energy G,~"
percent (Mpa Load Point to (J/m2)
Styrene m0.5) (lbfj Energy Break
(lbf in) (lbf
in)
Ex 3 78.1 2.9 59.5 0.95 2.9 3,130
Ex 4 80.4 2.8 67.6 1.3 2.8 2,770
Ex 5 84.9 3.4 56.8 0.94 2.1 3,430
Ex 6 91 2.9 46.6 0.97 2.6 2,880
Comp 100B 2.2 28.7 0.34 0.52 1,400
Expt
1
A Calculated using the measured Young's modulus and a Poisson's ratio of 0.33
B Free radical aPS, Mn=114,720, Mw=282,970, Mw/Mn=2.47
C Calculated from Klc using published values for Young's modulus (3.1 GPa) and
Poisson's ratio (0.33) for high molecular weight PS (Encyclopedia of Polymer
Science and Engineering, Vol. 16, 2 nd Ed., John Wiley & Sons, 1989, pp. 1-
246)
DMS analysis of the non-crystalline interpolymers was performed to determine
the
position of the glass transition and to identify other transitions associated
with these materials.
The glass transition temperature and room sub-Tg storage modulus increase with
increasing
styrene content in the copolymer.
In the shear loss modulus (G") response of the non-crystalline ES copolymers ,
the glass
transition temperatures for these materials were clearly observed, and a broad
transition was seen
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between ca. -50°C and room temperature. In polystyrene, this transition
has been attributed to
backbone relaxation that accompanies phenyl ring dislocation.
The physical properties of the high styrene content interpolymers of the
present invention
indicate have improved resistance to fracture. This suggests that these
interpolymers may provide
unique utility in certain applications. The amorphous interpolymers at the
highest styrene levels
were transparent, so that these polymers may have utility in film applications
and may be
advantaged with respect to aPS due to their increased toughness. Furthermore,
foam sheets of
these new polymers may show better resiliency than aPS sheets and may perform
better in
applications where improved durability was required. These polymers might also
be used to
toughen aPS while retaining good transparency, if compositions can be found
which display
compatibility.
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