Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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THERMOSET INTERPOLYMERS AND FOAMS
The subject invention pertains to thermoset interpolymers, to a process for
their
preparation, and to products fabricated from such thermoset interpolymers.
In one preferred embodiment, the present invention further pertains to foams
prepared from such thermoset interpolymers and to methods for the preparation
of
cross-linked a-olefin/vinyl or vinylidene aromatic monomer and/or hindered
aliphatic
vinyl or vinylidene monomer interpolymers.
Elastomers are defined as materials which experience large reversible
deformations under relatively low stress. Elastomers are typically
characterized as
having structural irregularities, non-polar structures, or flexible units in
the polymer
chain. Some examples of commercially available elastomers include natural
rubber,
ethylene/propylene (EPM) copolymers, ethylene/propylene/diene (EPDM)
copolymers,
styrene/butadiene copolymers, chlorinated polyethylene, and silicone rubber.
Thermoplastic elastomers are elastomers having thermoplastic properties. That
is, thermoplastic elastomers may be molded or otherwise shaped.and reprocessed
at
temperatures above their melting or softening point. One example of a
thermoplastic
elastomer is a styrene-butadiene-styrene (SBS) block copolymer. SBS block
copolymers exhibit a two phase morphology consisting of glassy polystyrene
domains
connected by rubbery butadiene segments. At temperatures between the glass
transition
temperatures of the butadiene midblock and the styrene endblocks, that is, at
temperatures from -90°C to 116°C, the SBS copolymer acts like a
crosslinked
elastomer.
European Patent Publication 416,815 discloses pseudorandom ethylene-styrene
interpolymers. Uncrosslinked pseudorandom ethylene/styrene interpolymers
exhibit a
decreased modulus at temperatures above the melting or softening point of the
interpolymer.
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SBS copolymers and uncrosslinked ethylene-styrene pseudorandom
interpolymers suffer the disadvantages of relatively low mechanical strength,
susceptibility to ozone degradation (to the extent that they have sites of
unsaturation in
the polymer backbone), and utility only in applications where the temperature
of the
elastomer will not exceed the melting or softening point of the elastomer.
In contrast, thermoset elastomers are elastomers having thermoset properties.
That is, thermoset elastomers irreversibly solidify or "set" when heated,
generally due
to an irreversible crosslinking reaction. Two examples of thermoset elastomers
are
crosslinked ethylene-propylene monomer rubber (EPM) and crosslinked ethylene-
propylene-dime monomer rubber (EPDM). EPM materials are made by the
copolymerization of ethylene and propylene. EPM materials are typically cured
with
peroxides to give rise to crosslinking, and thereby induce thermoset
properties. EPDM
materials are linear interpolymers of ethylene, propylene, and a nonconjugated
dime
such as 1,4-hexadiene, dicyclopentadiene, or ethylidene norbornene. EPDM
materials
are typically vulcanized with sulfur to induce thermoset properties, although
they
alternatively may be cured with peroxides. While EPM and EPDM materials are
advantageous in that they have applicability in higher temperature
applications, EPM
and EPDM elastomers suffer the disadvantages of low green strength (at lower
ethylene
contents), of a higher susceptibility of the cured elastomer to attack by oils
than
characteristic of styrene butadiene rubbers, and of resistance of the cured
elastomer to
surface modification.
Elastomers suitable for use over a broad range of temperatures and which are
also less susceptible to ozone degradation are desired. Thermoset elastomers
which are
prepared from elastomers having high green strength (which provides greater
flexibility
in their handling prior to curing) are particularly desired. Also desired, are
thermoset
elastomers which are resistant to oil, which are useful in fabricated parts
which
typically contact oil, such as automotive parts and gaskets. Also desired are
thermoset
elastomers which easily undergo surface modification, to promote surface
adhesion of
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the elastomer and/or to provide ionic sites on the elastomer surface. Also
desired is a
process for preparing such thermoset elastomers.
Thermoplastic vulcanizates are crystalline polyolefinic matrices through which
thenmoset elastomers are generally uniformly distributed. Examples of
thermoplastic
vulcanizates include EPM and EPDM thermoset materials distributed in a
crystalline
polypropylene matrix. Such thermoplastic vulcanizates are disadvantageous, in
that
they are susceptible to oil degradation. Thermoplastic vulcanizates which are
more
resistant to oil are desired. Also desired is a process for preparing such
thermoplastic
vulcanizates.
Interpolymers prepared from a-olelfin/vinylidene aromatic monomer or
hindered aliphatic vinylidene monomer have excellent properties; however, it
would be
desirable to have such polymers with improved properties.
It has been discovered that properties such as higher upper service
temperature,
improved melt processibility and self sticking tendencies of such
interpolymers can be
improved via crosslinking of the interpolymers.
The foams prepared from the cross-linked interpolyers are believed to have one
or more of the following improvements: improved upper service temperature,
lower
density, improved elastic recovery properties, improved mechanical properties
as
compared to non-crosslinked interpolymer foams.
The subject invention provides a thermoset product comprising a crosslinked
substantially random interpolymer comprising:
(1) from 1 to 65 mole percent of polymer units derived from
(a) at least one vinyl or vinylidene aromatic monomer, or
(b) at least one hindered aliphatic vinyl or vinylidene monomer, or
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(c) a combination of at least one vinyl or vinylidene aromatic monomer
and at least one hindered aliphatic vinyl or vinylidene monomer; and
(2) from 35 to 99 mole percent of polymer units derived from at least one
aliphatic
a-olefin having from 2 to 20 carbon atoms.
Another aspect of the present invention concerns a foamable compositon
comprising
(I) a partially or totally crosslinked composition comprising
(A) from 2 to 100 percent by weight based on the combined weight of
components (A) and (B) of at least one partially or totally crosslinked
substantially random interpolymer comprising
( 1 ) from 1 to 65 mole percent of polymer units derived from (a) at least
one vinyl or vinylidene aromatic monomer, or (b) at least one
hindered aliphatic vinyl or vinylidene monomer, or (c) a
combination of at least one vinyl or vinylidene aromatic monomer
and at least one hindered aliphatic vinyl or vinylidene monomer,
and
(2) from 35 to 99 mole percent of polymer units derived from at least
one aliphatic a-olefin having from 2 to 20 carbon atoms;
(B) from 0 to 98 percent by weight based on the combined weight of
components (A) and (B) of at least one of the following polymers:
(1) a partially or totally crosslinked homopolymer containing polymer units
derived from one or more a-olefins having from 2 to 20 carbon atoms;
(2) a partially or totally crosslinked copolymer containing (a) from 2 to 98
mole percent of polymer units derived from ethylene and (b) from 98 to 2
mole percent of polymer units derived from at least one of a-olefins having
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from 3 to 20 carbon atoms; acrylic acid, methacrylic acid, vinyl alcohol,
vinyl acetate, or dime having from 4 to 20 carbon atoms;
(3) a partially or totally crosslinked styrenic block copolymer;
(4) a partially or totally crosslinked substantially random interpolymer
defined
as in ( I ) wherein the interpolymers ( 1 ) and (4) are distinct in that:
(i) the amount of vinylidene aromatic monomer and/or hindered
aliphatic or cycloaliphatic vinylidene monomer in any
interpolymer of component ( 1 ) differs from that amount in any
interpolymer of component (4) by at least 0.5 mole percent; and/or
(ii) there is a difference of at least 20 percent between the number
average molecular weight (Mn) in any interpolymer of component
(1) and any interpolymer of component (4); and
(II) from 0.1 to 25 percent by weight based on the combined weight of
components
(I) and (II) of at least one foaming agent.
Another aspect of the present invention pertains to a method for cross-linking
a
polymer composition comprising
(A) from 2 to 100 percent by weight based on the combined weight of components
(A) and (B) of at least one partially or totally cross-linked substantially
random
interpolymer comprising
(1 ) from 1 to 65 mole percent of polymer units derived from (a) at least one
vinyl or vinylidene aromatic monomer, or (b) at least one hindered
aliphatic vinyl or vinylidene monomer, or (c) a combination of at least one
vinyl or vinylidene aromatic monomer and at least one hindered aliphatic
vinyl or vinylidene monomer, and
(2) from 35 to 99 mole percent of polymer units derived from at least one
aliphatic a-olefin having from 2 to 20 carbon atoms;
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(B) from 0 to 98 percent by weight based on the combined weight of components
(A)
and (B) of at least one of the following polymers:
( 1 ) a homogolymer containing polymer units derived from one or more a-
olefins having from 2 to 20 carbon atoms;
(2) a copolymer containing (a) from 2 to 98 mole percent of polymer units
derived from ethylene and (b) from 98 to 2 mole percent of polymer units
derived from at least one of a-olefins having from 3 to 20 carbon atoms;
acrylic acid, methacrylic acid, vinyl alcohol, vinyl acetate, dime having
from 4 to 20 carbon atoms;
(3) a styrenic block copolymer;
(4) an interpolymer defined as in (A) wherein the interpolymers (A) and (B4)
are distinct in that:
(i) the amount of vinyl or vinylidene aromatic monomer and/or
hindered aliphatic or cycloaliphatic vinyl or vinylidene monomer in
any interpolymer of component (A) differs from that amount in any
interpolymer of component (B4) by at least 0.5 mole percent; and/or
(ii) there is a difference of at least 20 percent between the number
average molecular weight (Mn) in any interpolyrner of component
(A) and any interpolymer of component (B4);
which process for cross-linking comprises
(a) subjecting the polymer composition to a sufficient amount of electron beam
radiation to at least partially cross-link the polymer composition; or
(b) contacting the polymer composition with a sufficient amount of at least
one
peroxide compound to at least partially cross-link the polymer composition; or
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(c) contacting the polymer composition with a sufficient amount of at least
one silane
compound to at least partially cross-link the polymer composition; or
(d} contacting the polymer composition with a sufficient amount of at least
one azide
compound to at least partially cross-link the polymer composition; or
(e) a combination of any two or more of the above cross-linking methods.
Another aspect of the present invention pertains to foams resulting from
subjecting the aforementioned foamable polymer compositions to foaming
conditions.
The subject invention further comprises fabricated parts comprising the
thermoset elastomers or thermoplastic vulcanizates or partially or totally
crosslinked
foams of the invention.
These and other embodiments are more fully described in the following detailed
description.
The term "polymer" as used herein refers to a polymeric compound prepared by
polymerizing monomers whether of the same or a different type. The generic
term
polymer thus embraces the term homopolymer, usually employed to refer to
polymers
prepared from only one type of monomer, and the term interpolymer as defined
hereinafter.
As used herein, the terms "crosslinked .interpolymers" and "thermoset
interpolymers" are used interchangeably, and mean interpolymers which have
greater
than 10 percent gel as determined in accordance with ASTM D-2765-84.
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
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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 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" as used herein refers to polymers prepared by the
polymerization of at least two different types of monomers. The generic term
interpolymer thus includes copolymers, usually employed to refer to polymers
prepared
from two different monomers, and polymers prepared from more than two
different
types of monomers.
Statements herein that a polymer or interpolymer comprises or contains certain
monomers, mean that such polymer or interpolymer comprises or contains
polymerized
therein units derived from such a monomer. For example, if a polymer is said
to
contain ethylene monomer, the polymer will have incorporated in it an ethylene
derivative, that is, -CH2-CH2-.
The term "hydrocarbyl" means any aliphatic, cycloaliphatic, aromatic, aryl
substituted aliphatic, aryl substituted cycloaliphatic, aliphatic substituted
aromatic, or
cycloaliphatic substituted aromatic groups. The aliphatic or cycloaliphatic
groups are
preferably saturated. Likewise, the term "hydrocarbyloxy" means a hydrocarbyl
group
having an oxygen linkage between it and the carbon atom to which it is
attached.
The term "monomer residue" or "polymer units derived from such monomer"
means that portion of the polymerizable monomer molecule which resides in the
polymer chain as a result of being polymerized with another polymerizable
molecule to
make the polymer chain.
The elastomeric thermoset compositions of the invention are preferably
substantially random interpolymers comprising an olefin and a vinyl aromatic
monomer, which interpolymers have been crosslinked to yield thermoset behavior
.
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The term "substantially random" in the substantially random interpoIymer
resulting from polymerizing one or more a-olefin monomers and one or more
vinyl or
vinylidene aromatic monomers or hindered aliphatic or cycloaliphatic vinyl or
vinylidene monomers, and optionally, with other polymerizable ethylenically
unsaturated monomers) as used herein means that the distribution of the
monomers of
said interpolymer can be described by the Bernoulli statistical model or by a
first or
second order Markovian statistical model, as described by J. C. Randall in
POLYMER
SEQUENCE DETERMINATION. Carbon-13 NMR Method, Academic Press New
York, 1977, pp. 71-78. Preferably, the substantially random interpolymer
resulting
from polymerizing one or more a-olefin monomers and one or more vinyl or
vinylidene
aromatic monomer, and optionally, with other polymerizable ethylenically
unsaturated
monomers) does not contain more than 15 percent of the total amount of vinyl
or
vinylidene aromatic monomer residue in blocks of vinyl or vinylidene aromatic
monomer of more than 3 units. More preferably, the interpolymer is not
characterized
by a high degree of either isotacticity or syndiotacticity. This means that in
the carbon
'3 NMR spectrum of the substantially random interpolymer the peak areas
corresponding to the main chain methylene and methine carbons representing
either
meso diad sequences or racemic diad sequences should not exceed 75 percent of
the
total peak area of the main chain methylene and methine carbons.
Pseudorandom interpolymers are a subset of substantially random
interpolymers. Pseudorandom interpolymers are characterized by an architecture
in
which all phenyl (or substituted phenyl) groups which are pendant from the
polymer
backbone are separated by two or more carbon backbone units. In other words,
the
pseudorandom interpolymers of the invention, in their noncrosslinked state,
can be
described by the following general formula (using styrene as the vinyl
aromatic
monomer and ethylene as the a-olefin for illustration):
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CHz CHz CH--CH2~CH2~CH
' j k
Noncrosslinked pseudorandom interpolymers are described in European Patent
Publication 416,815-A.
While not wishing to be bound by any particular theory, it is believed that
during the addition polymerization reaction of, for example, ethylene and
styrene, in the
presence of a constrained geometry catalyst as described below, if a styrene
monomer is
inserted into the growing polymer chain, the next monomer inserted will be an
ethylene
monomer or a styrene monomer inserted in an inverted or "tail-to-tail"
fashion. It is
believed that after an inverted or "tail-to-tail" styrene monomer is inserted,
the next
monomer will be ethylene, as the insertion of a second styrene monomer at this
point
would place it too close to the inverted styrene monomer, that is, less than
two carbon
backbone units away.
Preferably, the substantially random interpolymer will be characterized as
largely atactic, as indicated by a 13C-NMR spectrum in which the peak areas
corresponding to the main chain methylene and methine carbons representing
either
meso diad sequences or racemic diad sequences does not exceed 75 percent of
the total
peak area of the main chain methylene and methine carbons.
Substantially random interpolymers which are suitable as components (A) and
(B4) of the present invention include, substantially random interpolymers
prepared by
polymerizing i) one or more a-olefin monomers and ii) one or more vinyl or
vinylidene
aromatic monomers and/or one or more sterically hindered aliphatic or
cycloaliphatic
vinyl or vinylidene monomers, and optionally iii) other polymerizable
ethylenica.lly
unsaturated monomers)
Suitable a-olefins include for example, a-olefins containing from 2 to 20,
preferably from 2 to 12, more preferably from 2 to 8 carbon atoms.
Particularly
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suitable are ethylene, propylene, butene-1, 4-methyl-1-pentene, hexene-1 or
octene-1 or
ethylene in combination with one or more of propylene, butene-1, 4-methyl-1-
pentene,
hexene-1 or octene-1. These a-olefins do not contain an aromatic moiety.
Other optional polymerizable ethylenically unsaturated monomers) include
norbornene and C,.,o alkyl or C~,o aryl substituted norbornenes, with an
exemplary
interpolymer being ethylene/styrene/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
I
( I H2)n
R1 _ 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 monovinyl
aromatic
monomers include styrene, vinyl toluene, a-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, a-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 aromatic vinyl monomer is styrene.
By the term ""sterically hindered aliphatic or cycioaliphatic vinyl or
vinylidene
compounds", it is meant addition polymerizable vinyl or vinylidene monomers
corresponding to the formula:
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A~
I
R1 - C = C(R2)2
wherein A' is a sterically bulky, aliphatic or cycloaliphatic substituent of
up to 20
carbons, 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 RZ 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;
or
alternatively R' and A' together form a ring system. Preferred aliphatic or
cycloaliphatic vinyl or vinylidene compounds are monomers in which one of the
carbon
atoms bearing ethylenic unsaturation is tertiary or quaternary substituted.
Examples of
such substituents include cyclic aliphatic groups such as cyclohexyl,
cyclohexenyl,
cyclooctenyl, or ring alkyl or aryl substituted derivatives thereof, tert-
butyl, norbornyl.
Most preferred aliphatic or cycloaliphatic vinyl or vinylidene compounds are
the
various isomeric vinyl- ring substituted derivatives of cyclohexene and
substituted
cyclohexenes, and 5-ethylidene-2-norbornene. Especially suitable are 1-, 3-,
and 4-
vinylcyclohexene.
The substantially random 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 or chlorinated to provide
functionalized
derivatives according to established techniques. The substantially random
interpolyrners may also be modified by various chain extending or cross-
linking
processes including, but not limited to peroxide-, silane-, sulfur-, radiation-
, or azide-
based cure systems. A full description of the various cross-linking
technologies is
described in copending U.S. Patent Application No's 08/921,641 and 08/921,642
both
filed on August 27, 1997, 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. Dual cure systems are disclosed
and
claimed in U. S. Patent Application Serial No. 536,022, filed on September 29,
1995, in
the names of K. L. Walton and S. V. Karande, incorporated herein by reference.
For
instance, it may be desirable to employ peroxide crosslinking agents in
conjunction
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with silane crosslinking agents, peroxide crosslinking agents in conjunction
with
radiation, sulfur-containing crosslinking agents in conjunction with silane
crosslinking
agents, etc. The substantially random interpolymers may also be modified by
various
cross-linking processes including, but not limited to the incorporation of a
diene
component as a termonomer in its preparation and subsequent cross linking by
the
aforementioned methods and further methods including vulcanization via the
vinyl
group using sulfur for example as the cross linking agent.
The interpolymers of one or more a-olefins and one or more vinyl or vinylidene
aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic
vinyl or
vinylidene monomers employed in the present invention are substantially random
polymers. These interpolymers usually contain from 0.5 to 65, preferably from
1 to 55,
more preferably from 2 to 50 mole percent of at least one vinyl or vinylidene
aromatic
monomer and/or hindered aliphatic or cycloaliphatic vinyl or vinylidene
monomer and
from 35 to 99.5, preferably from 45 to 99, more preferably from 50 to 98 mole
percent
of at least one aliphatic a-olefin having from 2 to 20 carbon atoms.
Other optional polymerizable ethylenically unsaturated monomers) include
strained ring olefins such as norbornene and C,_",alkyl or C~_,~ aryl
substituted
norbornenes, with an exemplary interpolymer being ethylene/styrene/norbornene.
The number average molecular weight (Mn) of the polymers and interpolymers
is usually greater than 5,000, preferably from 20.000 to 1,000,000, more
preferably
from 50,000 to 500,000.
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. For example, while preparing the substantially random
interpolymer,
an amount of atactic vinyl or vinylidene aromatic homopolymer may be formed
due to
homopolymerization of the vinyl or vinylidene aromatic monomer at elevated
temperatures. The presence of vinyl or vinylidene aromatic homopolymer is in
general
not detrimental for the purposes of the present invention and can be
tolerated. The
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vinyl or vinylidene aromatic homopolymer may be separated from the
interpolymer, if
desired, by extraction techniques such as selective precipitation from
solution with a
non solvent for either the interpolymer or the vinyl or vinylidene aromatic
homopolymer. For the purpose of the present invention it is preferred that no
more
than 20 weight percent, preferably less than 15 weight percent based on the
total weight
of the interpolymers of vinyl or vinylidene aromatic homopolymer is present.
The conditions for polymerizing the a-olefin, vinyl or vinylidene aromatic,
and
optional dime are generally those useful in the solution polymerization
process,
although the application of the present invention is not limited thereto. High
pressure,
slurry and gas phase polymerization processes are also believed to be useful,
provided
the proper catalysts and polymerization conditions are employed.
In general, the polymerization useful in the practice of the subject invention
may be accomplished at conditions well known in the prior art for Ziegler-
Natta or
Kaminsky-Sinn type polymerizations.
1 S One method of preparation of the substantially random interpolymers
includes
polymerizing a mixture of polymerizable monomers in the presence of one or
more
metallocene or constrained geometry catalysts in combination with various
cocatalysts, as
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.
Such a method of preparation of the substantially random interpolymers
includes
polymerizing a mixture of polymerizable monomers in the presence of one or
more
metallocene or constrained geometry catalysts in combination with various
cocatalysts.
Preferred operating conditions for such polymerization reactions are pressures
from
atmospheric up to 3000 atmospheres and temperatures from -30°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.
Examples of suitable catalysts and methods for preparing the substantially
random
interpolymers are disclosed in U.S. Application Serial No. 702,475, filed May
20, 1991
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(EP-A-514,828); as well as U.S. Patents: 5,055,438; 5,057,475; 5,096,867;
5,064,802;
5,132,380; 5,189,192; 5,321,106; 5,347,024; 5,350,723; 5,374,696; 5,399,635;
5,470,993;
5,703,187; and 5,721,185 all of which patents and applications are
incorporated herein by
reference.
The substantially random a-olefin/vinyl aromatic interpolymers can also be
prepared by the methods described in JP 07/278230 employing compounds shown by
the general formula
~ CP1 R1
R3
Cp2 R
where Cp' and Cpz are cyclopentadienyl groups, indenyl groups, fluorenyl
groups, or
substituents of these, independently of each other; R' and R2 are hydrogen
atoms,
halogen atoms, hydrocarbon groups with carbon numbers of 1-12, alkoxyl groups,
or
aryloxyl groups, independently of each other; M is a group IV metal,
preferably Zr or
Hf, most preferably Zr; and R3 is an alkylene group or silanediyl group used
to cross-
link Cp' and Cp2).
The substantially random a-olefin/vinyl aromatic interpolymers can also be
prepared by the methods described by John G. Bradfute et al. (W. R. Grace &
Co.) in
WO 95/32095; by R. B. Pannell (Exxon Chemical Patents, Inc.) in WO 94/00500;
and
in Plastics Technolosv, p. 25 (September 1992), all of which are incorporated
herein by
reference in their entirety.
Also suitable are the substantially random interpolymers which comprise at
least one a-olefin/vinyl aromatic/vinyl aromatic/a-olefin tetrad disclosed in
U. S.
Application No. 08/708,809 filed September 4, 1996 and WO 98/09999 both by
Francis
J. Timmers et al. These interpolymers contain additional signals in their
carbon-13
NMR spectra with intensities greater than three times the peak to peak noise.
These
signals appear in the chemical shift range 43.70 - 44.25 ppm and
38.0 - 38.5 ppm. Specifically, major peaks are observed at 44.1, 43.9, and
38.2 ppm. A
proton test NMR experiment indicates that the signals in the chemical shift
region
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43.70 - 44.25 ppm are methine carbons and the signals in the region 38.0 -
38.5 ppm are
methylene carbons.
It is believed that these new signals are due to sequences involving two head-
to-
tail vinyl aromatic monomer insertions preceded and followed by at least one a-
olefin
insertion, for example an ethylene/styrene/styrene/ethylene tetrad wherein the
styrene
monomer insertions of said tetrads occur exclusively in a 1,2 (head to tail)
manner. It is
understood by one skilled in the art that for such tetrads involving a vinyl
aromatic
monomer other than styrene and an a-olefin other than ethylene that the
ethylene/vinyl
aromatic monomer/vinyl aromatic monomer/ethylene tetrad will give rise to
similar
carbon-13 NMR peaks but with slightly different chemical shifts.
These interpolymers can be prepared by conducting the polymerization at
temperatures of from -30°C to 250°C in the presence of such
catalysts as those
represented by the formula
CP
(E~m ~ R.2
C~,
wherein: each Cp is independently, each occurrence, a substituted
cyclopentadienyl
group ~c-bound to M; E is C or Si; M is a group IV metal, preferably Zr or Hf,
most
preferably Zr; each R is independently, each occurrence, H, hydrocarbyl,
silahydrocarbyl, or hydrocarbylsilyl, containing up to 30 preferably from 1 to
20 more
preferably from 1 to 10 carbon or silicon atoms; each R' is independently,
each
occurrence, H, halo, hydrocarbyl, hyrocarbyloxy, silahydrocarbyl,
hydrocarbylsilyl
containing up to 30 preferably from 1 to 20 more preferably from 1 to 10
carbon or
silicon atoms or two R' groups together can be a C,_,o hydrocarbyl substituted
1,3-
butadiene; m is 1 or 2; and optionally, but preferably in the presence of an
activating
cocatalyst. Particularly, suitable substituted cyclopentadienyl groups include
those
illustrated by the formula:
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(R)3
wherein each R is independently, each occurrence, H, hydrocarbyl,
silahydrocarbyl, or
hydrocarbylsilyl, containing up to 30 preferably from 1 to 20 more preferably
from 1 to
carbon or silicon atoms or two R groups together form a divalent derivative of
such
5 group. Preferably, R independently each occurrence is (including where
appropriate all
isomers) hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl, phenyl
or silyl or
(where appropriate) two such R groups are linked together forming a fused ring
system
such as indenyl, fluorenyl, tetrahydroindenyl, tetrahydrofluorenyl, or
octahydrofluorenyl.
10 Particularly preferred catalysts include, for example. racemic-
(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl))zirconium dichloride,
racemic-
(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl))zirconium 1,4-diphenyl-1,3-
butadiene, racemic-(dimethylsilanediyl)-bis-(2-methyl-4-
phenylindenyl))zirconium di-
C1-4 alkyl, racemic-(dimethylsilanediyl)-bis-(2-methyl-4-
phenylindenyl))zirconium di-
C1-4 alkoxide, or any combination thereof .
It is also possible to use the following titanium-based constrained geometry
catalysts, [N-{1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-rl)-1,5,6,7-
tetrahydro-s-
indacen-1-yl]silanaminato(2-)-N]titanium dimethyl; (1-indenyl}(tert-
butylamido)dimethyl-silane titanium dimethyl; ((3-tert-butyl)(1,2,3,4,5-rl)-1-
indenyl)(tert-butylamido) dimethylsilane titanium dimethyl; and ((3-iso-
propyl)(1,2,3,4,5-rl)-1-indenyl)(tert-butyl amido)dimethylsilane titanium
dimethyl, or
any combination thereof.
Further preparative methods for the interpolymers used in the present
invention
have been described in the literature. Longo and Grassi (Makromol. Chem.,
Volume
191, pages 2387 to 2396 [1990]) and D'Anniello et al. (Journal of Applied
Polymer
Science, Volume 58, pages 1701-1706 [1995]) reported the use of a catalytic
system
based on methylalumoxane (MAO) and cyclopentadienyltitanium trichloride
(CpTiCl3)
to prepare an ethylene-styrene copolymer. Xu and Lin (Polymer Preprints, Am.
Chem.
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WO 99/10395 PCTNS98/17673
Soc.. Div. Polym. Chem.l Volume 35, pages 686,687 [1994]) have reported
copolymerization using a MgCI~/TiCl4/NdCl3/ Al(iBu), catalyst to give random
copolymers of styrene and propylene. Lu et al (Journal of Applied Polymer
Science,
Volume 53, pages 1453 to 1460 [I994]) have described the copolymerization of
ethylene and styrene using a TiCl4/NdCl3/ MgClz /Al(Et)3 catalyst. Sernetz and
Mulhaupt, (Macromol. Chem. Phvs., v. 197, pp. 1071-1083, 1997) have described
the
influence of polymerization conditions on the copolymerization of styrene with
ethylene using MeZSi(Me4Cp)(N-tent-butyl)TiClz/methylaluminoxane Ziegler-Natta
catalysts. Copolymers of ethylene and styrene produced by bridged metallocene
catalysts have been described by Arai, Toshiaki and Suzuki (Polymer Preprints,
Am.
Chem. Soc.. Div. Polym. Chem.) Volume 38, pages 349, 350 [1997]) and in United
States patent number 5,652,315, issued to Mitsui Toatsu Chemicals, Inc. The
manufacture of a-olefin/vinyl aromatic monomer interpolymers such as
propylene/styrene and butene/styrene are described in United States patent
number
5,244,996, issued to Mitsui Petrochemical Industries Ltd or United States
patent
number 5,652,315 also issued to Mitsui Petrochemical Industries Ltd or as
disclosed in
DE 197 11 339 A1 to Denki Kagaku Kogyo KK. All the above methods disclosed for
preparing the interpolymer component are incorporated herein by reference.
The level of vinyl or vinylidene aromatic monomer incorporated in the
thermoset elastomers of the invention is at least 30, preferably at least 35
weight
percent based on the weight of the interpolymer. The vinyl or vinylidene
aromatic
monomer is typically incorporated in the interpolymers of the invention in an
amount
less than 70, more typically less than 60 weight percent based on the weight
of the
interpolymer.
The substantially random interpolymers usually contain from 0.5 to 65,
preferably from 1 to 55, more preferably from 2 to 50 mole percent of at least
one vinyl
or vinylidene aromatic monomer and/or hindered aliphatic or cycloaliphatic
vinyl or
vinylidene monomer and from 35 to 99.5, preferably from 45 to 99, more
preferably
from 50 to 98 mole percent of at least one aliphatic a-olefin having from 2 to
20 carbon
atoms.
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One or more dienes can optionally be incorporated into the interpolymer to
provide functional sites of unsaturation on the interpolymer useful, for
example, to
participate in crosslinking reactions. While conjugated dimes such as
butadiene, 1,3-
pentadiene (that is, piperylene), or isoprene may be used for this purpose,
nonconjugated dienes are preferred. Typical nonconjugated dimes include, for
example the open-chain nonconjugated diolefins such as 1,4-hexadiene (see U.S.
Patent
No. 2,933,480) and 7-methyl-1,6-octadiene (also known as MOCD); cyclic dimes;
bridged ring cyclic dimes, such as dicyclopentadiene (see U.S. Patent No.
3,211,709);
or alkylidenenorbornenes, such as methylenenorbornene or ethylidenenorbornene
(see
U.S. Patent No. 3,151,173). The nonconjugated dimes are not limited to those
having
only two double bonds, but rather also include those having three or more
double
bonds.
The diene is incorporated in the elastomers of the invention in an amount of
from 0 to 15 weight percent based on the total weight of the interpolymer.
When a
dime is employed, it will preferably be provided in an amount of at least 2
weight
percent, more preferably at least 3 weight percent, and most preferably at
least 5 weight
percent, based on the total weight of the interpolymer. Likewise, when a diene
is
employed, it will be provided in an amount of no more than 15, preferably no
more
than 12 weight percent based on the total weight of the interpolymer.
The number average molecular weight (Mn) of the polymers and interpolymers
is usually greater than 5,000, preferably from 20,000 to 1,000,000, more
preferably
from 50,000 to 500,000.
Comnoundin~yand Curine the Substantially random Interool mers
The thermoset eiastomers of the invention may include various additives, such
as carbon black, silica, titanium dioxide, colored pigments, clay, zinc oxide,
stearic
acid, accelerators, curing agents, sulfur, stabilizers, antidegradants,
processing aids,
adhesives, tackifiers, plasticizers, wax, precrosslinking inhibitors,
discontinuous fibers
(such as wood cellulose fibers) and extender oils. Such additives may be
provided
either prior to, during, or subsequent to curing the substantially random
interpolymers.
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The substantially random interpolymers are typically mixed with a filler, an
oil, and a
curing agent at an elevated temperature to compound them. The compounded
material
is the subsequently cured at a temperature which is typically greater than
that employed
during compounding.
Preferably, carbon black will be added to the substantially random
interpolymer
prior to curing. Carbon black is typically added to improve the tensile
strength or
toughness of the compounded product, but can also be used as an extender or to
mask
the color of the compounded product. Carbon black will typically be provided
in an
amount from 0 to 80 weight percent, typically from 0.5 to SO weight percent,
based on
i 0 the total weight of the formulation. When the carbon black is employed to
mask a
color, it is typically employed in the range of 0.5 to 10 weight percent,
based on the
weight of the formulation. When the carbon black is employed to increase
toughness
and/or decrease the cost of the formulation, it is typically employed in
amounts greater
than 10 weight percent based on the weight of the formulation.
Moreover, preferably, one or more extender oils will be added to the
substantially random interpolymer prior to curing. Extender oils are typically
added to
improve processability and low temperature flexability, as well as to decrease
cost.
Suitable extender oils are listed in Rubber World Blue Book 1975 Edition,
Materials
and Compounding Ingredients for Rubber, pages 145-190. Typical classes of
extender
oils include aromatic, naphthenic, and paraffinic extender oils. The extender
oils) will
typically be provided in an amount from 0 to 50 weight percent. When employed,
the
extender oil will typically be provided in an amount of at least 5 weight
percent, more
typically in an amount of from 15 to 25 weight percent, based on the total
weight of the
formulation.
The curing agents) will typically be provided in an amount of from 0.5 to 12
weight percent, based on the total weight of the formulation.
Suitable curing agents include peroxides, phenols, azides, aldehyde-amine
reaction products, substituted areas, substituted guanidines; substituted
xanthates;
substituted dithiocarbamates; sulfur-containing compounds, such as thiazoles,
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imidazoles, sulfenamides, thiuramidisulfides, paraquinonedioxime,
dibenzoparaquinonedioxime, sulfur; and combinations thereof. See Encyclopedia
of
Chemical Technology, Vol. 17, 2nd edition, Interscience Publishers, 1968; also
Organic
Peroxides, Daniel Seern, Vol. 1, Wiley-interscience. 1970).
Suitable peroxides include aromatic diacyl peroxides; aliphatic diacyl
peroxides; dibasic acid peroxides; ketone peroxides; alkyl peroxyesters; alkyl
hydroperoxides (for example, diacetylperoxide; dibenzoylperoxide; bis-2,4-
dichlorobenzoyl peroxide; di-tert-butyl peroxide; dicumylperoxide; tert-
butylperbenzoate; tert-butylcumylperoxide; 2,5-bis (t-butylperoxy}-2,5-
dimethylhexane; 2,5-bis (t-butylperoxy)-2,5-dimethylhexyne-3; 4,4,4',4'-tetra-
(t-
butylperoxy)-2,2-dicyclohexylpropane; 1,4-bis-(t-butylperoxyisopropyl)-
benzene; l,l-
bis-(t-butylperoxy)-3,3,5-trimethylcyclohexane; lauroyl peroxide; succinic
acid
peroxide; cyclohexanone peroxide; t-butyl peracetate; butyl hydroperoxide;
etc.
Suitable phenols are disclosed in USP 4,311.628. the disclosure of which is
incorporated herein by reference. One example of a phenolic cure agent is the
condensation product of a halogen substituted phenol or a C 1-C 1 p alkyl
substituted
phenol with an aldehyde in an alkaline medium, or by condensation of
bifunctional
phenoldialcohols. One such class of phenolic cure agents is dimethylol phenols
substituted in the para position with C5-C10 alkyl group(s). Also suitable are
halogenated alkyl substituted phenol curing agents, and cure systems
comprising
methylol phenolic resin, a halogen donor, and a metal compound.
Suitable azides include azidoformates, such as tetramethylenebis(azidoformate)
(see, also, USP 3,284,421, Breslow, Nov. 8, 1966); aromatic polyazides, such
as 4,4'-
diphenylmethane diazide (see, also, USP 3,297,674, Breslow et al., Jan. 10,
1967); and
sulfonazides, such as p,p'-oxybis(benzene sulfonyl azide).
The poly(sulfonyl azide) is any compound having at least two sulfonyl azide
groups (-SO2N3} reactive with thesubstantially random interpolymer. Preferably
the
poly(sulfonyl azide)s have a structure X-R-X wherein each X is SOZN3 and R
represents
an unsubstituted or inertly substituted hydrocarbyl, hydrocarbyl ether or
silicon-
containing group, preferably having sufficient carbon, oxygen or silicon,
preferably
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carbon, atoms to separate the sulfonyl azide groups sufficiently to permit a
facile
reaction between the substantially random interpolymer and the sulfonyl azide,
more
preferably at least 1, more preferably at least 2, most preferably at least 3
carbon,
oxygen or silicon, preferably carbon, atoms between functional groups. The
term
inertly substituted refers to substitution with atoms or groups which do not
undesirably
interfere with the desired reactions) or desired properties of the resulting
crosslinked
polymers. Such groups include fluorine, aliphatic or aromatic ether,
siloxanes, as well
as sulfonyl azide groups when more than two substantially random interpolymer
chains
are to be joined. Suitable structures include R as aryl, alkyl, aryl alkaryl,
arylalkyl
silane, or heterocyclic, groups and other groups which are inert and separate
the
sulfonyl azide groups as described. More preferably R includes at least one
aryl group
between the sulfonyl groups, most preferably at least two aryl groups (such as
when R
is 4,4' diphenylether or 4,4'-biphenyl). When R is one aryl group, it is
preferred that
the group have more than one ring, as in the case of naphthylene bis(sulfonyl
azides).
Poly(sulfonyl)azides include such compounds as 1, 5-pentane bis(sulfonyl
azide),
1,8-octane bis(sulfonyl azide), 1,10-decane bis(sulfonyl azide}, 1,10-
octadecane
bis(sulfonyl azide), 1-octyl-2,4,6-benzene tris(sulfonyl azide), 4,4'-diphenyl
ether
bis(sulfonyl azide), 1,6-bis(4'-sulfonazidophenyl)hexane, 2,7-naphthalene
bis(sulfonyl
azide), and mixed sulfonyl azides of chlorinated aliphatic hydrocarbons
containing an
average of from 1 to 8 chlorine atoms and from 2 to 5 sulfonyl azide groups
per
molecule, and mixtures thereof. Preferred poly(sulfonyl azides) include oxy-
bis(4-
sulfonylazidobenzene), 2,7-naphthalene bis(sulfonyl azido), 4,4'-bis(sulfonyl
azido)biphenyl, 4,4'-diphenyl ether bis(sulfonyl azide) and bis(4-sulfonyl
azidophenyl)methane, and mixtures thereof.
To crosslink, the poly(sulfonyl azide) is used in a crosslinking amount, that
is
an amount effective to crosslink the substantially random interpolymer as
compared
with the starting material substantially random interpolymer, that is
sufficient
poly(sulfonyl azide) to result in the formation of at least 10 weight percent
gels as
evidenced by insolubility of the gels in boiling xylene when tested according
to ASTM
D-2765A-84. The amount is preferably at least 0.5, more preferably at least
1.0, most
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preferably 2.0 weight percent poly(sulfonyl azide) based on total weight of
substantially
random interpolymer, with these values depending on the molecular weight of
the azide
and the molecular weight or melt index of the substantially random
interpolymer. To
avoid uncontrolled heating and unnecessary cost, and/or degradation of
physical
properties, the amount of poly(sulfonyl azide) is preferably less than 10
weight percent,
more preferably less than 5.
For crosslinking, the sulfonyl azide is admixed with the substantially random
interpolymer and heated to at least the decomposition temperature of the
sulfonyi azide,
that is usually greater than 100°C and most frequently greater than
150°C. The
preferred temperature range depends on the nature of the azide that is used.
For
example, in the case of 4,4'-disulfonylazidediphenylether the preferred
temperature
range is greater than 150°C, preferably greater than 160°C, more
preferably greater than
185°C, most preferably greater than 190°C. Preferably, the upper
temperature is less
than 250°C.
Suitable aldehyde-amine reaction products include formaldehyde-ammonia;
formaldehyde-ethylchloride-ammonia; acetaldehyde-ammonia; formaldehyde-
aniline;
butyraldehyde-aniline; and heptaldehyde-aniline.
Suitable substituted areas include trimethylthiourea; diethylthiourea;
dibutylthiourea; tripentylthiourea; 1,3-bis(2-
benzothiazolylmercaptomethyl)urea; and
N,N-diphenylthiourea.
Suitable substituted guanidines include diphenylguanidine; di-o-
tolylguanidine;
diphenylguanidine phthalate; and the di-o-tolylguanidine salt of dicatechol
borate.
Suitable substituted xanthates include zinc ethylxanthate; sodium
isopropylxanthate; butylxanthic disulfide; potassium isopropylxanthate; and
zinc
butylxanthate.
Suitable dithiocarbamates include copper dimethyl-, zinc dimethyl-, tellurium
diethyl-, cadmium dicyclohexyl-, lead dimethyl-, lead dimethyl-, selenium
dibutyl-,
zinc pentamethylene-, zinc didecyl-, and zinc isopropyloctyI-dithiocarbamate.
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Suitable thiazoles include 2-mercaptobenzothiazole, zinc mercaptothiazolyl
mercaptide, 2-benzothiazolyl-N,N-diethylthiocarbamyl sulfide, and
2,2'-dithiobis(benzothiazole).
Suitable imidazoles include 2-mercaptoimidazoline and 2-mercapto-4,4,6-
trimethyldihydropyrimidine.
Suitable sulfenamides include N-t-butyl-2-benzothiazole-, N-
cyclohexylbenzothiazole-, N,N-diisopropylbenzothiazole-, N-(2,6-
dimethylmorpholino)-2-benzothiazole-, and N,N-diethylbenzothiazole-
sulfenamide.
Suitable thiuramidisulfides include N,N'-diethyl-, tetrabutyl-, N,N'-
diisopropyldioctyl-, tetramethyl-, N,N'-dicyclohexyl-, and N,N'-tetralauryl-
thiuramidisulfide.
Those skilled in the art will be readily able to select amounts of
crosslinking
agent, with the amount selected taking into account characteristics of the
substantially
random interpolymer or blend comprising such substantially random
interpolymer, such
as molecular weight, molecular weight distribution, comonomer content, the
presence
of crosslinking enhancing coagents, additives (such as oil) etc. Since it is
expressly
contemplated that the substantially random interpolymer may be blended with
other
polymers prior to crosslinking, those skilled in the art may use the following
guidelines
as a reference point in optimizing the amount of crosslinking agent preferred
for the
particular blends in question.
For instance, in the case of crosslinking using dicumyl peroxide, when the
substantially random interpolymer is characterized as having less than 35
weight
percent styrene, dicumyl peroxide will typically be provided in an amount of
at least
0.1 weight percent, preferably at least 1 weight percent, more preferably at
least 2
weight percent based on the combined weight of polymer and peroxide.
Further, in the case of crosslinking using dicumyl peroxide, when the
substantially random interpolymer is characterized as having from at least 35
to 60
weight percent styrene, dicumyl peroxide will typically be provided in an
amount of at
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least 0.3 weight percent, preferably at least 3 weight percent, more
preferably at least
4 weight percent based on the combined weight of polymer and peroxide.
Further, in the case of crosslinking using dicumyl peroxide, when the
substantially random interpolymer is characterized as having greater than 60
weight
percent styrene, dicumyl peroxide will typically be provided in an amount of
at least 1
weight percent, preferably at least 6 weight percent, more preferably at least
9 weight
percent based on the combined weight of polymer and peroxide.
Typically, the amount of crosslinking agent employed will not exceed that
which is required to effect the desired level of crosslinking. For instance,
dicumyl
peroxide will typically not be employed in an amount greater than 15 weight
percent,
preferably no more than 12 weight percent based on the combined weight of
polymer
and peroxide.
Alternatively, silane crosslinking agents may be employed. In this regard, any
silane that will effectively graft to and crosslink the substantially random
interpolymers
can be used in the practice of this invention. Suitable silanes include
unsaturated
silanes that comprise an ethylenically unsaturated hydrocarbyl group, such as
a vinyl,
allyl, isopropenyl, butenyl, cyclohexenyl or y-(meth}acryloxy allyl group, and
a
hydrolyzable group, such as, for example, a hydrocarbyloxy, hydrocarbonyloxy,
or
hydrocarbylamino group. Examples of hydrolyzable groups include methoxy,
ethoxy,
formyloxy, acetoxy, proprionyloxy, and alkyl or arylamino groups. Preferred
silanes
are the unsaturated alkoxy silanes which can be grafted onto the polymer.
These
silanes and their method of preparation are more fully described in USP
5,266,627 to
Meverden, et al. Vinyl trimethoxy silane, vinyl triethoxy silane, y-
{meth)acryloxy
propyl trimethoxy silane and mixtures of these silanes are the preferred
silane
crosslinkers for use in this invention.
The amount of silane crosslinking agent used in the practice of this invention
can vary widely depending upon the nature of the substantially random
interpolymer,
the silane employed, the processing conditions, the amount of grafting
initiator, the
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ultimate application, and similar factors. Typically, in the case of
crosslinking using
vinyltrimethoxysilane (VTMOS), the VTMOS will typically be provided in an
amount
of at least 0.1 weight percent, preferably at least 1 weight percent, more
preferably at
least 3 weight percent based on the combined weight of polymer and silane.
Considerations of convenience and economy are usually the two principal
limitations on the maximum amount of silane crosslinker used in the practice
of this
invention. For instance, when VTMOS is employed. the maximum amount of VTMOS
employed will typically not exceed 10 weight percent. and more preferably does
not
exceed 8, and most preferably does not exceed 6 weight percent based on the
combined
I O weight of polymer and silane.
The silane crosslinking agent is grafted to the substantially random
interpolymer
by any conventional method, typically in the presence of a free radical
initiator for
example peroxides and azo compounds, or by ionizing radiation, etc. Organic
initiators
are preferred, such as any one of the peroxide initiators, for example,
dicumyl peroxide,
15 di-tert-butyl peroxide, t-butyl perbenzoate, benzoyl peroxide, cumene
hydroperoxide, t-
butyl peroctoate, methyl ethyl ketone peroxide, 2,5-dimethyl-2,5-di(t-butyl
peroxy)hexane, lauryl peroxide, and tent-butyl peracetate. A suitable azo
compound is
azobisisobutyl nitrite.
Those skilled in the art will be readily able to select amounts of initiator
20 employed, with the amount selected taking into account characteristics of
the
substantially random interpolymer, such as molecular weight, molecular weight
distribution, comonomer content, as well as the presence of crosslinking
enhancing
coagents, additives (such as oil) etc.
The amount of initiator will depend upon the percent of vinyl or vinylidene
25 aromatic or hindered aliphatic or cycloaliphatic comonomer present in the
substantially
random interpolymer. For instance, in the case of crosslinking using VTMOS,
when
the substantially random interpolymer is characterized as having less than 35
weight
percent styrene, dicumyl peroxide will typically be provided in an amount of
at least
250 ppm, preferably at least 500 ppm, more preferably at least 1,500 ppm based
on the
30 combined weight of polymer, silane and initiator.
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Further, in the case of crosslinking using VTMOS, when the substantially
random interpolymer is characterized as having from at least 35 to 60 weight
percent
styrene, dicumyl peroxide will typically be provided in an amount of at least
400 ppm,
preferably at least 1,000 ppm, more preferably at least 2,000 ppm based on the
combined weight of polymer, silane and initiator.
Further, in the case of crosslinking using VTMOS, when the substantially
random interpolymer is characterized as having greater than 60 weight percent
styrene,
dicumyl peroxide will typically be provided in an amount of at least 500 ppm,
preferably at least 1,500 ppm, more preferably at least 3000 ppm based on the
combined weight of polymer, silane and initiator.
Typically, the amount of initiator employed will not exceed that which is
required to effect grafting. For instance, dicumyl peroxide will typically not
be
employed in an amount greater than 20,000 ppm, preferably not greater than
10,000
ppm based on the combined weight of polymer, silane and initiator.
While any conventional method can be used to graft the silane crosslinker to
the
substantially random interpolymer, one preferred method is blending the two
with the
initiator in the first stage of a reactor extruder, such as a Buss kneader.
The grafting
conditions can vary, but the melt temperatures are typically between
160°C and 260°C
C, preferably between 190°C and 230°C, depending upon the
residence time and the
half life of the initiator.
Cure is promoted with a crosslinking catalyst, and any catalyst that will
provide
this function can be used in this invention. These catalysts generally include
organic
bases, carboxylic acids, and organometallic compounds including organic
titanates and
complexes or carboxylates of lead, cobalt, iron, nickel, zinc and tin.
Dibutyltindilaurate, dioctyltinmaleate, dibutyltindiacetate,
dibutyltindioctoate, stannous
acetate, stannous octoate, lead naphthenate, zinc caprylate, cobalt
naphthenate. Tin
carboxylate, especially dibutyltindilaurate and dioctyltinmaleate, are
particularly
effective for this invention. The catalyst (or mixture of catalysts) is
present in a
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catalytic amount, typically between 0.015 and 0.035 weight percent based on
the
combined weight of polymer, silane, initiator and catalyst.
Rather than employing a chemical crosslinking agent, crosslinking may be
effected by use of radiation. Useful radiation types include electron beam or
beta ray,
S gamma rays, X-rays, or neutron rays. Radiation is believed to effect
crosslinking by
generating polymer radicals which may combine and crosslink. Additional
teachings
concerning radiation crosslinking are seen in C. P. Park, "Polyolefin Foam"
Chapter 9,
Handbook of Polymer Foams and Technology, D. Klempner and K. C. Frisch, eds.,
Hanser Publishers, New York (1991), pages 198 - 204, which is incorporated
herein by
reference.
Radiation dosage depends upon the composition of the substantially random
interpolymer. Generally speaking, as the amount of the vinyl or vinylidene
aromatic or
hindered aliphatic or cycloaliphatic comonomer increases, greater dosages will
be
required to cause the desired level of crosslinking, that is, to lead to
compositions
exhibiting at least 10 percent gel, preferably at least 20 percent gel, and
more preferably
at least 30 percent gel. Those skilled in the art will be readily able to
select suitable
radiation levels, taking into account such variables as thickness and geometry
of the
article to be irradiated, as well as to characteristics of the substantially
random
interpolymer, such as molecular weight, molecular weight distribution,
comonomer
content, the presence of crosslinking enhancing coagents, additives (such as
oil), etc.
For instance, in the case of crosslinking of 80 mil plaques by e-beam
radiation,
when the substantially random interpolymer is characterized as having less
than 35
weight percent styrene, typical radiation dosages will be greater than 5 Mrad,
preferably
greater than 10 Mrad, more preferably greater than 15 Mrad. Electronic
radiation
dosages are referred to herein in terms of the radiation unit "RAD", with one
million
RADs or a megarad being designated as "Mrad."
Further, in the case of crosslinking of 80 mil plaques by e-beam radiation,
when
the substantially random interpolymer is characterized as having from at least
35 to 60
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weight percent styrene, typical radiation dosages will be greater than 5 Mrad,
preferably
greater than 15 Mrad, more preferably greater than 20 Mrad.
Further, in the case of crosslinking of 80 mil plaques by e-beam radiation,
when
the substantially random interpolymer is characterized as having greater than
60 weight
percent styrene, typical radiation dosages will be greater than 10 Mrad,
preferably
greater than 15 Mrad, more preferably greater than 20 Mrad.
Typically, the dosage will not exceed that which is required to effect the
desired
level of crosslinking. For instance, dosages above 80 Mrad are not typically
employed.
In the case of substantially random interpolymers not including the optional
diene component, peroxide or azide cure systems are preferred; in the case of
interpolymer with high styrene content (> than 50 wt. percent) azide cure
systems are
preferred; in the case of substantially random interpolymers including the
optional
diene component, sulfur-based (for example, containing sulfur, a
dithiocarbamate, a
thiazole, an imidazole, a sulfenamide, a thiuramidisulfide or combinations
thereof) and
1 S phenolic cure systems are preferred.
In certain embodiments of the claimed invention. dual cure systems, which use
a combination of heat, moisture cure, and radiation steps, may be effectively
employed.
Dual cure systems are disclosed and claimed in U. S. Patent Application Serial
No.
536,022, filed on September 29, 1995, in the names of K. L. Walton and S. V.
Karande,
incorporated herein by reference. 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.
Preparation of Polymer Blends
Olefinic polymers suitable for use as components (B1, B2 and B3) employed in
the present invention are aliphatic a-olefin homopolymers or interpolymers, or
interpolymers of one or more aliphatic a-olefins and one or more non-aromatic
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monomers interpolymerizable therewith such as C,-CZO a-olefins or those
aliphatic a-
olefins having from 2 to 20 carbon atoms and containing polar groups. Suitable
aliphatic a-olefin monomers which introduce polar groups into the polymer
include, for
example, ethylenically unsaturated nitriles such as acrylonitrile,
methacrylonitrile,
ethacrylonitrile, etc.; ethylenically unsaturated anhydrides such as malefic
anhydride;
ethylenically unsaturated amides such as acrylamide, methacrylamide etc.;
ethylenically
unsaturated carboxylic acids (both mono- and difunctional) such as acrylic
acid and
methacrylic acid, etc.; esters (especially lower, for example C,-C6, alkyl
esters) of
ethylenically unsaturated carboxylic acids such as methyl methacrylate, ethyl
acrylate,
hydroxyethylacrylate, n-butyl acrylate or methacrylate, 2-ethyl-hexylacrylate
etc.;
ethylenically unsaturated vinyl alcohols, such as ethylene vinyl alcohol
(EVOH);
ethylenically unsaturated dicarboxylic acid imides such as N-alkyl or N-aryl
maleimides such as N-phenyl maleimide, etc. Preferably such monomers
containing
polar groups are acrylic acid, vinyl acetate, malefic anhydride and
acrylonitrile.
Halogen groups which can be included in the polymers from aliphatic a-olefin
monomers include fluorine, chlorine and bromine; preferably such polymers are
chlorinated polyethylenes (CPEs). Preferred olefinic polymers for use in the
present
invention are homopolymers or interpolymers of an aliphatic, including
cycloaliphatic,
a-olefin having from 2 to 18 carbon atoms. Suitable examples are homopolymers
of
ethylene or propylene, and interpolymers of two or more a-olefin monomers.
Other
preferred olefinic polymers are interpolymers of ethylene and one or more
other a-
olefins having from 3 to 8 carbon atoms. Preferred comonomers include 1-
butene, 4-
methyl-1-pentene, 1-hexene, and 1-octene. The olefinic polymer blend component
(B)
may also contain, in addition to the a-olefin, one or more non-aromatic
monomers
interpolymerizable therewith. Such additional interpolymerizable monomers
include,
for example, C4 Czo dimes, preferably, butadiene or 5-ethylidene-2-norbornene.
The
olefinic polymers can be further characterized by their degree of long or
short chain
branching and the distribution thereof.
One class of olefmic polymers is generally produced by a high pressure
polymerization process using a free radical initiator resulting in the
traditional long
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chain branched low density polyethylene (LDPE}. LDPE employed in the present
composition usually has a density of less than 0.94 g/cc (ASTM D 792) and a
melt
index of from 0.01 to 100, and preferably from 0.1 to 50 grams per 10 minutes
(as
determined by ASTM Test Method D 1238, condition I).
Another class is the linear olefin polymers which have an absence of long
chain
branching, as the traditional linear low density polyethylene polymers
(heterogeneous
LLDPE) or linear high density polyethylene polymers (HDPE) made using Ziegler
polymerization processes (for example, U.S. Patent No. 4,076,698 (Anderson et
al.),
sometimes called heterogeneous polymers.
HDPE consists mainly of long linear polyethylene chains. The HDPE
employed in the present composition usually has a density of at least 0.94
grams per
cubic centimeter (g/cc) as determined by ASTM Test Method D 792, and a melt
index
(ASTM-1238, condition I) in the range of from 0.01 to 100, and preferably from
0.1 to
50 grams per 10 minutes.
The heterogeneous LLDPE employed in the present composition generally has a
density of from 0.85 to 0.94 g/cc (ASTM D 792), and a melt index (ASTM-1238,
condition I) in the range of from 0.01 to 100, and preferably from 0.1 to SO
grams per
10 minutes. Preferably the LLDPE is an interpolymer of ethylene and one or
more
other a-olefins having from 3 to 18 carbon atoms, more preferably from 3-8
carbon
atoms. Preferred comonomers include 1-butene, 4-methyl-1-pentene, 1-hexene,
and 1-
octene.
A further class is that of the uniformly branched or homogeneous ethylene
polymers. The homogeneous linear ethylene polymers contain no long chain
branches
and have only branches derived from the monomers (if having more than two
carbon
atoms). Homogeneous linear ethylene polymers include those made as described
in
U.S. Patent 3,645,992 (Elston), and those made using so-called single site
catalysts in a
batch reactor having relatively high olefin concentrations (as described in
U.S. Patent
Nos. 5,026,798 and 5,055,438 (Canich). The uniformly branched/homogeneous
linear
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ethylene polymers are those polymers in which the comonomer is randomly
distributed
within a given interpolymer molecule and wherein the interpolymer molecules
have a
similar ethylene/comonomer ratio within that interpolymer.
The homogeneous linear ethylene polymer employed in the present composition
generally has a density of from 0.85 to 0.94 g/cc (ASTM D 792), and a melt
index
(ASTM-1238, condition I) in the range of from 0.01 to 100, and preferably from
0.1 to
50 grams per 10 minutes. Preferably the homogeneous linear ethylene polymer is
an
interpolymer of ethylene and one or more other a-olefins having from 3 to 18
carbon
atoms, more preferably from 3-8 carbon atoms. Preferred comonomers include 1-
butene, 4-methyl-1-pentene, 1-hexene, and 1-octene.
Further, there is the class of substantially linear olefin polymers (SLOP}
that
may advantageously be used in component (B) of the blends of the present
invention.
These polymers have a processability similar to LDPE, but the strength and
toughness
of LLDPE. Similar to the traditional homogeneous polymers, the substantially
linear
I 5 ethylene/a-olefin interpolymers have only a single melting peak, as
opposed to
traditional Ziegler polymerized heterogeneous linear ethylene/a-olefin
interpolymers
which have two or more melting peaks (determined using differential scanning
calorimetry). Substantially linear olefin polymers are disclosed in U.S.
Patent Nos.
5,272,236 and 5,278,272 which are incorporated herein by reference.
The density of the SLOP as measured in accordance with ASTM D-792 is
generally from 0.85 g/cc to 0.97 g/cc, preferably from 0.85 g/cc to 0.955
g/cc, and
especially from 0.85 g/cc to 0.92 g/cc.
The melt index, according to ASTM D-1238, Condition 190°C/2.16 kg
(also
known as IZ), of the SLOP is generally from 0.01 g/10 min. to 1000 g/10 min.,
preferably from 0.01 g/10 min. to 100 g/10 min., and especially from 0.01 g/10
min. to
10 g/10 min.
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Also, included are the ultra low molecular weight ethylene polymers and
ethylene/a-olefin interpolymers described in the patent application entitled
Ultra-low
Molecular Weight Polymers, filed provisionally on January 22, 1996 in the
names of
M. L. Finlayson, C. C. Garrison, R. E. Guerra, M. J. Guest, B. W. S.
Kolthammer, D.
R. Parikh, and S. M. Ueligger, which is incorporated herein by reference.
These
ethylene/a-olefin interpolymers have Iz melt indices greater than 1,000 g/10
min., or a
number average molecular weight (Mn) less than 11.000.
The SLOP can be a homopolymer of a C,-C,o olefin, such as ethylene,
propylene, 4-methyl-1-pentene, etc., or it can be an interpolymer of ethylene
with at
least one C3 Czo a-olefin and/or C,-Czo acetylenically unsaturated monomer
and/or C4-
C,$ diolefin. The SLOP can also be an interpolymer of ethylene with at least
one of the
above C3-C,o a-olefins, diolefins andlor acetytenically unsaturated monomers
in
combination with other unsaturated monomers.
Especially preferred olefin polymers suitable for use as component (B)
comprise
LDPE, HDPE, heterogeneous LLDPE, homogeneous linear ethylene polymers, SLOP,
polypropylene (PP), especially isotactic polypropylene and rubber toughened
polypropylenes, or ethylene-propylene interpolymers (EP), or chlorinated
polyolefins
(CPE), or ethylene-vinyl acetate copolymers (EVA). or ethylene-acrylic acid
copolymers (EAA), or any combination thereof.
The term "block copolymer" is used herein to mean elastomers having at least
one block segment of a hard polymer unit and at least one block segment of a
rubber
monomer unit. However, the term is not intended to include thermoelastic
ethylene
interpolymers which are, in general, random polymers. Preferred block
copolymers
contain hard segments of styrenic type polymers in combination with saturated
or
unsaturated rubber monomer segments. The structure of the block copolymers
useful in
the present invention is not critical and can be of the linear or radial type,
either diblock
or triblock, or any combination of thereof. Preferably, the predominant
structure is that
of triblocks and more preferably that of linear triblocks.
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The preparation of the block copolymers useful herein is not the subject of
the
present invention. Methods for the preparation of such block copolymers are
known in
the art. Suitable catalysts for the preparation of useful block copolymers
with
unsaturated rubber monomer units include lithium based catalysts and
especially
lithium-alkyls. U.S. Pat. No. 3,595,942 describes suitable methods for
hydrogenation
of block copolymers with unsaturated rubber monomer units to from block
copolymers
with saturated rubber monomer units. The structure of the polymers is
determined by
their methods of polymerization. For example, linear polymers result by
sequential
introduction of the desired rubber monomer into the reaction vessel when using
such
initiators as lithium-alkyls or dilithiostilbene, or by coupling a two segment
block
copolymer with a difunctional coupling agent. Branched structures, on the
other hand,
may be obtained by the use of suitable coupling agents having a functionality
with
respect to the block copolymers with unsaturated rubber monomer units of three
or
more. Coupling may be effected with multifunctional coupling agents such as
dihaloalkanes or alkenes and divinyl benzene as well as with certain polar
compounds
such as silicon halides, siloxanes or esters of monohydric alcohols with
carboxylic
acids. The presence of any coupling residues in the polymer may be ignored for
an
adequate description of the block copolymers forming a part of the composition
of this
invention.
Suitable block copolymers having unsaturated rubber monomer units includes,
but is not limited to, styrene-butadiene (SB), styrene-isoprene(SI), styrene-
butadiene-
styrene (SBS), styrene-isoprene-styrene (SIS), -methylstyrene-butadiene-
methylstyrene
and -methylstyrene-isoprene-methylstyrene.
The styrenic portion of the block copolymer is preferably a polymer or
interpolymer of styrene and its analogs and homologs including a-methylstyrene
and
ring-substituted styrenes, particularly ring-methylated styrenes. The
preferred styrenics
are styrene and methylstyrene, and styrene is particularly preferred.
Block copolymers with unsaturated rubber monomer units may comprise
homopolymers of butadiene or isoprene and copolymers of one or both of these
two
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dienes with a minor amount of styrenic monomer. When the monomer employed is
butadiene, it is preferred that between 35 and 55 mol percent of the condensed
butadiene units in the butadiene polymer block have 1,2 configuration. Thus,
when
such a block is hydrogenated, the resulting product is, or resembles a regular
copolymer
block of ethylene and 1-butene (EB). If the conjugated dime employed is
isoprene, the
resulting hydrogenated product is or resembles a regular copolymer block of
ethylene
and propylene (EP). Preferred block copolymers with saturated rubber monomer
units
comprise at least one segment of a styrenic unit and at least one segment of
an ethylene-
butene or ethylene-propylene copolymer. Preferred examples of such block
copolymers
with saturated rubber monomer units include styrene/ethylene-butene
copolymers,
styrene/ethylene-propylene copolymers, styrene/ethylene-butene/styrene (SEBS)
copolymers, and styrene/ethylene-propylene/styrene (SEPS) copolymers.
I-Iydrogenation of block copolymers with unsaturated rubber monomer units is
preferably effected by use of a catalyst comprising the reaction products of
an
aluminum alkyl compound with nickel or cobalt carboxylates or alkoxides under
such
conditions as to substantially completely hydrogenate at least 80 percent of
the aliphatic
double bonds while hydrogenating no more than 25 percent of the styrenic
aromatic
double bonds. Preferred block copolymers are those where at least 99 percent
of the
aliphatic double bonds are hydrogenated while less than 5 percent of the
aromatic
double bonds are hydrogenated.
The proportion of the styrenic blocks is generally between 8 and 65 percent by
weight of the total weight of the block copolymer. Preferably, the block
copolymers
contain from 10 to 35 weight percent of styrenic block segments and from 90 to
65
weight percent of rubber monomer block segments, based on the total weight of
the
block copolymer.
The average molecular weights of the individual blocks may vary within certain
limits. In most instances, the styrenic block segments will have number
average
molecular weights in the range of 5,000 to 125,000, preferably from 7,000 to
60,000
while the rubber monomer block segments will have average molecular weights in
the
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range of 10,000 to 300,000, preferably from 30,000 to 150,000. The total
average
molecular weight of the block copolymer is typically in the range of 25,000 to
250,000,
preferably from 35,000 to 200,000. These molecular weights are most accurately
determined by tritium counting methods or osmotic pressure measurements.
Further, the various block copolymers suitable for use in the present
invention
may be modified by graft incorporation of minor amounts of functional groups,
such as,
for example, malefic anhydride by any of the methods well known in the art.
Block copolymers useful in the present invention are commercially available,
such as, for example, supplied by Shell Chemical Company under the designation
of
KRATON and supplied by Dexco Polymers under the designation of VECTOR.
Likewise, blends of the substantially random interpolymer with
polyvinylchloride (PVC) or ethylene vinyl alcohol (EVOH) may be suitably
employed.
PreQaration of Thermoplastic Vulcanizates
The thermoset compositions of the invention may be incorporated into
polyolefins to form thermoplastic vulcanizates. The proportions of ingredients
utilized
will vary somewhat with the particular polyolefin employed, with the desired
application, as well as with the character of the crosslinked substantially
random
interpolymer and compounding ingredients. Typically, as the amount of the
crosslinked substantially random interpolymer increases, the stiffness of the
resultant
thermoplastic vulcanizate decreases. The thermoplastic vulcanizates of the
invention
will typically comprise from 10 to 90 weight percent of the polyolefm and from
10 to
90 weight percent of the crosslinked substantially random interpolymer.
Suitable polyolefms include thermoplastic, crystalline, high molecular weight
polymers prepared by the polymerization of one or more monoolefins. Examples
of
suitable polyolefms include ethylene and the isotactic and syndiotactic
monoolefin
polymer resins, such as propylene, 1-butene, 1-pentene, 1-hexene, 2-methyl-1-
propene,
3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene and mixtures
thereof.
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Most typically, the thermoplastic vulcanizates of the invention will utilize
isotactic
polypropylene as the polyolefin component.
The thermoplastic vulcanizates of the invention are preferably prepared by
dynamic vulcanization, wherein a mixture of the noncrosslinked substantially
random
interpolymer is mixed with the polyolefin resin and an appropriate curing
agent to form
a blend, which is then masticated at vulcanization temperature. In particular,
the
noncrosslinked substantially random interpolymer is blended with a polyolefin
at a
temperature above the melting point of the polyolefin. After the substantially
random
interpolymer and polyolefin are intimately mixed, an appropriate curing agent
is added,
such as are described above with respect to the compounding and curing of the
substantially random interpolymers. The blend is subsequently masticated using
conventional masticating equipment, such as a Banbury mixer, Brabender mixer,
or a
mixing extruder. The temperature of the blend during mastication is that
sufficient to
effect vulcanization of the substantially random interpolymer. A suitable
range of
vulcanization temperatures is from the melting temperature of the polyolefin
resin
(120°C in the case of polyethylene and 175°C in the case of
polypropylene) to the
temperature at which the substantially random interpolymer. the polyolefin, or
the
curing agent degrades. Typical temperatures are from 180°C to
250°C, preferably from
180°C to 200°C.
Methods other than the dynamic vulcanization of the substantially random
interpolymer/polyolefin are likewise suitable. For instance, the substantially
random
interpolymer may be crosslinked prior to introduction to the polyolefin. The
crosslinked substantially random interpolymer may then be powdered and mixed
with
the polyolefin at a temperature above the melting or softening point of the
poIyolefin.
Provided that the crosslinked substantially random interpolymer particles are
small,
well-dispersed, and in an appropriate concentration, (that is, provided an
intimate
mixture of the crosslinked substantially random interpolymer and polyolefin is
achieved}, the thermoplastic vulcanizates of the invention may be readily
obtained.
Should such an intimate mixture not be achieved, the resultant product will
contain
visually observable islands of the crosslinked substantially random
interpolymer. In
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this case, the part may be comminuted by pulverizing or by cold milling to
reduce
particle size to below 50 microns. Upon adequate comminution, the particles
may be
remolded into a part exhibiting more uniform composition and the enhanced
properties
characteristic of the thermoplastic vulcanizates of the invention.
The thermoplastic vulcanizates of the invention may include various additives,
such as carbon black, silica, titanium dioxide, colored pigments, clay, zinc
oxide,
stearic acid, accelerators, vulcanizing agents, sulfur, stabilizers,
antidegradants,
processing aids, adhesives, tackifiers, plasticizers, wax, prevulcanization
inhibitors,
discontinuous fibers (such as wood cellulose fibers) and extender oils. Such
additives
may be provided either prior to, during, or subsequent to vulcanization.
Preparation of Foams
The foam structure of the present invention may take any physical
configuration
known in the art, such as sheet, plank,injection molded articles, or bun
stock. Other
useful forms are expandable or foamable particles, moldable foam particles, or
beads,
and articles formed by expansion and/or coalescing and welding of those
particles.
Excellent teachings to processes for making ethylenic polymer foam structures
and processing them are seen in C.P. Park. "Polyolefin Foam", Chapter 9,
Handbook of
Polymer Foams and Technology, edited by D. Klempner and K. C. Frisch, Hanser
Publishers, Munich, Vienna, New York, Barcelona (1991), which is incorporated
herein
by reference.
The present foam structure may be prepared by blending and heating a polymer
material comprising at least one substantially random interpolymer and a
decomposable chemical blowing agent to form a foamable plasticized or melt
polymer
material, extruding the foamable melt polymer material through a die, inducing
cross-
linking in the melt polymer material, and exposing the melt polymer material
to an
elevated temperature to release the blowing agent to form the foam structure.
The
polymer material and the chemical blowing agent may be mixed and melt blended
by
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any means known in the art such as with an extruder, mixer, or blender. The
chemical
blowing agent is preferably dry-blended with the polymer material prior to
heating the
polymer material to a melt form, but may also be added when the polymer
material is
in melt phase. Cross-linking may be induced by addition of a cross-linking
agent or by
radiation. Induction of cross-linking and exposure to an elevated temperature
to effect
foaming or expansion may occur simultaneously or sequentially. If a cross-
linking
agent is used, it is incorporated into the polymer material in the same manner
as the
chemical blowing agent. Further, if a cross-linking agent is used, the
foamable melt
polymer material is heated or exposed to a temperature of preferably less than
150°C
to prevent decomposition of the cross-linking agent or the blowing agent and
to
prevent premature cross-linking. If radiation cross-linking is used, the
foamable melt
polymer material is heated or exposed to a temperature of preferably less than
160°C
to prevent decomposition of the blowing agent. The foamable melt polymer
material
is extruded or conveyed through a die of desired shape to form a foamable
structure.
The foamable structure is then cross-linked and expanded at an elevated or
high
temperature (typically, 150°C-250°C) such as in an oven to form
a foam structure. If
radiation cross-linking is used, the foamable structure is irradiated to cross-
link the
polymer material, which is then expanded at the elevated temperature as
described
above. The present structure can advantageously be made in sheet or thin plank
form
according to the above process using either cross-linking agents or radiation.
The present foam structure may also be made into a continuous plank structure
by an extrusion process utilizing a long-land die as described in GB 2,145,961
A. In
that process, the polymer, decomposable blowing agent and cross-linking agent
are
mixed in an extruder, heating the mixture to let the polymer cross-link and
the blowing
agent to decompose in a long-land die; and shaping and conducting away from
the foam
structure through the die with the foam structure and the die contact
lubricated by a
proper lubrication material.
The present foam structure may also be formed into cross-linked foam beads
suitable for molding into articles. To make the foam beads, discrete resin
particles
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such as granulated resin pellets are: suspended in a liquid medium in which
they are
substantially insoluble such as water; impregnated with a cross-linking agent
and a
blowing agent at an elevated pressure and temperature in an autoclave or other
pressure vessel; and rapidly discharged into the atmosphere or a region of
reduced
pressure to expand to form the foam beads. A version is that the polymer beads
is
impregnated with blowing agent, cooled down, discharged from the vessel, and
then
expanded by heating or with steam. Blowing agent may be impregnated into the
resin
pellets while in suspension or, alternately, in non-hydrous state. The
expandable beads
are then expanded by heating with steam and molded by the conventional molding
method for the expandable polystyrene foam beads.
The foam beads may then be molded by any means known in the art, such as
charging the foam beads to the mold, compressing the mold to compress the
beads,
and heating the beads such as with steam to effect coalescing and welding of
the beads
to form the article. Optionally, the beads may be pre-heated with air or other
blowing
agent prior to charging to the mold. Excellent teachings of the above
processes and
molding methods are seen in C.P. Park, above publication, pp. 227-233, U.S.
Patent
No. 3,886,100, U.S. Patent No. 3,959,189, U.S. Patent No. 4,168,353, and U.S.
Patent
No. 4,429,059. The foam beads can also be prepared by preparing a mixture of
polymer, cross-linking agent, and decomposable mixtures in a suitable mixing
device
or extruder and form the mixture into pellets, and heat the pellets to cross-
link and
expand.
In another process for making cross-linked foam beads suitable for molding
into articles, the substantially random interpolymer material is melted and
mixed with
a physical blowing agent in a conventional foam extrusion apparatus to form an
essentially continuous foam strand. The foam strand is granulated or
pelletized to
form foam beads. The foam beads are then cross-linked by radiation. The cross-
linked foam beads may then be coalesced and molded to form various articles as
described above for the other foam bead process. Additional teachings to this
process
are seen in U.S. Patent No. 3,616,365 and C.P. Park, above publication, pp.
224-228.
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The present foam structure may be made in bun stock form by two different
processes. One process involves the use of a cross-linking agent and the other
uses
radiation.
The present foam structure may be made in bun stock form by mixing the
S substantially random interpolymer material, a cross-linking agent, and a
chemical
blowing agent to form a slab, heating the mixture in a mold so the cross-
linking agent
can cross-link the polymer material and the blowing agent can decompose, and
expanding by release of pressure in the mold. Optionally, the bun stock formed
upon
release of pressure may be re-heated to effect further expansion.
Cross-linked polymer sheet may be made by either irradiating polymer sheet
with high energy beam or by heating a polymer sheet containing chemical cross-
linking
agent. The cross-linked polymer sheet is cut into the desired shapes and
impregnated
with nitrogen in a higher pressure at a temperature above the softening point
of the
polymer; releasing the pressure effects nucleation of bubbles and some
expansion in the
sheet. The sheet is re-heated at a lower pressure above the softening point,
and the
pressure is then released to allow foam expansion.
Blowing agents and foaming agents as employed herein are interchangeable and
have the same meaning.
Blowing agents useful in making the present foam structure include
decomposable chemical blowing agents. Such chemical blowing agents decompose
at
elevated temperatures to form gases or vapors to blow the polymer into foam
form.
The agent preferably takes a solid form so it may be easily dry-blended with
the
polymer material. Chemical blowing agents include azodicarbonamide,
azodiisobutyro-nitrite, benzenesulfonhydrazide, 4,4-oxybenzene sulfonyl-
semicarbazide, p-toluene sulfonyl semi-carbazide, barium azodicarboxylate,
N,N'-
dimethyl-N,N'-dinitrosoterephthalamide, N,N'-dinitrosopentamethylenetetramine,
4-4-
oxybis (benzenesulfonylhydrazide), and trihydrazino triazine. Azodicarbonamide
is
preferred. Additional teachings to chemical blowing agents are seen in C.P.
Park,
-41-
CA 02300062 2000-02-11
WO 99!10395 PCT/US98/17673
above publication, pp. 205-208, and F.A. Shutov, "Polyolefin Foam", Handbook
of
Polymer Foams and Technology, pp. 382-402, D. Klemper and K.C. Frisch, Hanser
Publishers, Munich, Vienna, New York, Barcelona ( 1991 ).
The chemical blowing agent is blended with the polymer material in an amount
sufficient to evolve 0.2 to 5.0, preferably from 0.5 to 3.0, and most
preferably from 1.0
to 2.50 moles of gas or vapor per kilogram of polymer.
In some processes for making the present structure, a physical blowing agent
may be used. Physical blowing agents include organic and inorganic agents.
Suitable
inorganic blowing agents include carbon dioxide, nitrogen, argon, water, air,
nitrogen,
and helium. Organic blowing agents include aliphatic hydrocarbons having 1-9
carbon
atoms, aliphatic alcohols having 1-3 carbon atoms, and fully and partially
halogenated
aliphatic hydrocarbons having 1-4 carbon atoms. Aliphatic hydrocarbons include
methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, and
neopentane.
Aliphatic alcohols include methanol, ethanol, n-propanol, and isopropanol.
Fully and
partially halogenated aliphatic hydrocarbons include fluorocarbons,
chlorocarbons, and
chlorofluorocarbons. Examples of fluorocarbons include methyl fluoride,
perfluoromethane, ethyl fluoride, 1,1-difluoroethane (HFC-152a), 1,1,1-
trifluoroethane
(HFC-143a), 1,1,1,2-tetrafluoro-ethane (HFC-134a), pentafluoroethane,
difluoromethane, perfluoroethane, 2,2-difluoropropane, 1,1,1-trifluoropropane,
perfluoropropane, dichloropropane, difluoropropane, perfluorobutane,
perfluorocyclobutane. Partially halogenated chlorocarbons and
chlorofluorocarbons
for use in this invention include methyl chloride, methylene chloride, ethyl
chloride,
1,1,1-trichloroethane, 1,1-dichloro-1-fluoroethane (HCFC-141b}, 1-chloro-1,1-
difluoroethane (HCFC-142b), chlorodifluoromethane (HCFC-22), 1,1-dichloro-
2,2,2-
trifluoroethane (HCFC-123) and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124).
Fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-
11 ), dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane (CFC-113),
1,1,1-trifluoroethane, pentafluoroethane, dichlorotetrafluoroethane (CFC-114),
chloroheptafluoropropane, and dichlorohexafluoropropane.
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CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
The amount of blowing agent incorporated into the polymer melt material to
make a foam-forming polymer gel is from 0.2 to 5.0, preferably from 0.5 to
3.0, and
most preferably from 1.0 to 2.50 moles per kilogram of polymer.
Various additives may be incorporated in the present foam structure such as
stability control agents, nucleating agents, inorganic fillers, pigments,
antioxidants,
acid scavengers, ultraviolet absorbers, flame retardants, processing aids and
extrusion
aids.
A stability control agent may be added to the present foam to enhance
dimensional stability. Preferred agents include amides and esters of C 10-24
fatty
acids. Such agents are seen in U. S. Pat Nos. 3,644,230 and 4,214,054, which
are
incorporated herein by reference. Most preferred agents include stearyl
stearamide,
glycerol monostearate, glycerol monobehenate, and sorbitol monostearate.
Typically,
such stability control agents are employed in an amount ranging from 0.1 to 10
parts
per hundred parts of the polymer.
In addition, a nucleating agent may be added in order to control the size of
foam
cells. Preferred nucleating agents include inorganic substances such as
calcium
carbonate, talc, clay, titanium oxide, silica, barium sulfate, diatomaceous
earth,
mixtures of citric acid and sodium bicarbonate. The amount of nucleating agent
employed may range from 0.01 to 5 parts by weight per hundred parts by weight
of a
polymer resin.
The foam structure has density of less than 250, more preferably less than 100
and most preferably from 10 to 70 kilograms per cubic meter. The foam has an
average
cell size of from 0.05 to 5.0, more preferably from 0.2 to 2.0, and most
preferably 0.3 to
1.8 millimeters according to ASTM D3576.
The foam structure may take any physical configuration known in the art, such
as extruded sheet, rod, plank, and profiles. The foam structure may also be
formed by
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WO 99/10395 PCT/US98/17673
molding of expandable beads into any of the foregoing configurations or any
other
configuration.
The foam structure may be closed-celled or open-celled according to ASTM
D2856-A.
In one embodiment of the invention, the compositions of the invention will be
utilized in cable insulation and/or cable jacketing. The cable insulation of
this
invention can be filled or unfilled. If filled, then the amount of filler
present should not
exceed an amount that would cause degradation of the electrical and/or
mechanical
properties of the interpolymers. Typically, the amount of filler present is
between 20
and 80, preferably between SO and 70, weight percent (wt percent) based on the
weight
of the polymer. Representative fillers include kaolin clay, magnesium
hydroxide,
silica, calcium carbonate. In a preferred embodiment of this invention in
which a filler
is present, the filler is coated with a material that will prevent or retard
any tendency
that the filler might otherwise have to interfere with the cure reactions.
Stearic acid is
IS illustrative of such a filler coating. Other additives can be used in the
preparation of
and be present in the insulation of this invention, and include antioxidants,
processing
aids, pigments and lubricants.
In another embodiment of this invention, the compositions of the invention,
particularly the silane-grafted substantially random interpolymers, are shaped
into
automotive weatherstripping, gaskets or seals. This weatherstripping is useful
as a
sealing system for doors, trunks, belt lines, hoods, and similar items. These
materials
can be processed on conventional thermoplastic equipment. The articles made
from
crosslinked interpolymers should have better sound insulation than
conventional sulfur-
cured EPDM weatherstripping.
In yet another embodiment of this invention, crosslinkable fibers may be
prepared. In one specific embodiment, a substantially random interpolymer is
provided
with an effective amount of a peroxide or an azide compound, as described
herein. The
resultant mixture is extruded into fibers, which are then heated to cause
crosslinking.
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
In another specific embodiment, the substantially random interpolymer is
extruded into fibers, which are then crosslinked by irradiation with an
effective amount
of radiation, such as is described herein.
In another specific embodiment, silane-grafted substantially random
interpolymers are shaped into fibers, which exhibit improved heat resistance.
These
fibers are readily crosslinked upon exposure to moisture which can be affected
by
immersion in water or by exposure to atmospheric moisture.
The resultant crosslinked fibers are usefully employed in woven and non-woven
fabric (for example washable clothing), elastic string (for example woven
elastic strap),
elastic filters for air/water filtration (for example non-woven air cleaners),
and fiber
mats (for example non-woven carpet underlayment).
As in the case of the thermoset elastomers of the invention, carbon black will
preferably be added to the blend of the substantially random interpolymer and
polyolefin prior to vulcanization. Carbon black will typically be provided in
an amount
from 0 to 50 weight percent, typically from 0.5 to 50 weight percent, based on
the
total formulation weight. When the carbon black is employed to mask a color,
it is
typically employed in the range of 0.5 to 10 weight percent, based on the
total weight
of the formulation. When the carbon black is employed to increase toughness
and/or
decrease cost, it is typically employed in amounts greater than 10 weight
percent, based
on the total weight of the formulation.
Moreover, as in the case of the thermoset elastomers of the invention, one or
more extender oils will preferably be added to the blend of the substantially
random
interpolymer and polyolefin prior to vulcanization. Suitable extender oils are
listed in
Rubber World Blue Book 1975 Edition, Materials and Compounding Ingredients for
Rubber, pages 145-190. Typical classes of extender oils include aromatic,
naphthenic,
and paraffinic extender oils. The extender oils) will typically be provided in
an
amount from 0 to 50 weight percent based on the total formulation weight. When
employed, the extender oil will typically be provided in an amount of at least
5 weight
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CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
percent, more typically in an amount of from 15 to 25 weight percent, based on
the total
weight of the formulation.
Additives such as antioxidants (for example, hindered phenols such as, for
example, Irganox~ 1010), phosphites (for example, Irgafos~ 168)), U. V,
stabilizers,
cling additives (for example, polyisobutylene), antiblock additives,
colorants, pigments,
fillers, can also be included in the interpolymers employed in the blends of
and/or
employed in the present invention, to the extent that they do not interfere
with the
enhanced properties discovered by Applicants.
The 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 amounts 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
amount of
filler loading 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 polymer or polymer blend. However, in the
instance of
fillers, they could be employed in amounts up to 90 percent by weight based on
the
weight of the polymer or polymer blend.
In one preferred embodiment, the thermoplastic vulcanizates of the invention
will comprise from 30 to 60 weight percent of the substantially random
interpolymer,
from 15 to 55 weight percent of the thermoplastic polyolefin, and from 15 to
30 weight
percent of the extender oil. Such thermoplastic vulcanizates are particularly
useful as
moldings for automotive applications.
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CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
In a particularly preferred embodiment, the thermoplastic vulcanizates of the
invention are characterized by an ASTM #2 oil swell of less than 60 percent,
as
determined by ASTM D-471.
Test Procedures
Monomer contents are determined by carbon-13 NMR spectroscopy.
Stress-strain properties are determined on an Instron model 1122 load frame
using 0.870 inch (2.2 cm) micro-tensile samples measured at an extension rate
of 5
inch/min (12.7 cm/min). Tensile break, elongation at break, and 100 percent
modulus
are measured in accordance with ASTM D-412.
Melt index is measured in accordance with ASTM D-1238.
Molecular weight and molecular weight distribution are determined by gel
permeation chromatography.
ASTM #2 and #3 oil swells are measured in accordance with ASTM D-471.
Hardness shore "A" is measured in accordance with ASTM D-2240.
Compression set is measured in accordance with ASTM D-395.
Percent gel content (% crosslinking) is measured in accordance with ASTM D-
2765-84, using a xylene extraction method. Approximately 1 gram of sample is
weighed out and was transferred to a mesh basket which is then placed in
boiling
xylene for 12 hours. After 12 hours, the sample baskets are removed and placed
in a
vacuum oven at 150 °C and 28 in. of Hg vacuum for 12 hours. After 12
hours, the
samples are removed, allowed to cool to room temperature over a 1 hour period,
and
then weighed. The percent polymer extracted is calculated as:
Percent polymer extracted = ((initial weight - final weight) / initial weight)
x 100
The reported value, percent gel, is calculated as:
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CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
Percent Gel = 100 - percent extracted polymer
The upper service temperature is determined using a Perkin Elmer model TMA
7 thermo-mechanical analyzer (TMA). Probe force of 102 g and heating rate of
5°C/min were used. The test specimen was a disk with thickness of about
2 mm in
diameter, prepared by melting pressing at 205 °C and air-cooling to
room temperature.
Example 1 Preparation of Ethylene-Styrene Interpolymers and Thermoset
Elastomers
Ethylene/styrene copolymers were made using (tert-
butylamido)dimethyl(tetramethyl-rls-cyclopenta-dienyl)silane
dimethyltitanium(+4)
catalyst and tris(pentafluorophenyl)borane cocatalyst in a one to one molar
ratio
according to the following procedure. A two liter reactor was charged with 360
grams
( 500 mL) of ISOPART"" E mixed alkane solvent (available from Exxon Chemicals
Inc.)
and the desired amount of styrene comonomer. Hydrogen was added to the reactor
by
differential pressure expansion from a 75 mL addition tank. The reactor was
heated to
the run temperature and was saturated with ethylene at the desired pressure.
(Tert-
butylamido)dimethyl-(tetramethyl-rls-cyclopentadienyl)silane dimethyltitanium
(IV)
catalyst and tris(pentafluorophenyl)borane cocatalyst were mixed in a dry box
by
pipeting the desired amount of a 0.005 M solution of the
tris(pentafluorophenyl)borane
cocatalyst in ISOPART"" E mixed alkane solvent or toluene into a solution of
the (tert-
butylamido)dimethyl-(tetramethyl-rls-cyclopentadienyl)silane dimethyl-titanium
(IV)
catalyst in ISOPART"" E mixed alkane solvent or toluene. The resulting
catalyst
solution was transferred to a catalyst addition tank and was injected into the
reactor.
The polymerization was allowed to proceed, with ethylene being introduced on
demand. Additional charges of catalyst and cocatalyst, if used, were prepared
in the
same manner and were added to the reactor periodically. The total amount of
catalyst
employed was set forth in Table One. In each instance, the amount of
tris(pentafluorophenyl)borane cocatalyst (on a molar basis) equals the amount
of (tert-
butylamido}dimethyl-(tetramethyl-rls-cyclopentadienyl)silane dimethyltitanium
(IV)
-4s-
-_ CA 02300062 2000-02-11
40874D
a a ve eeee ee eeee ee W
, a a a
v a o a v a , a a a
W a ~a a a a c ~ W aec
eW a ua «c
- a ~ c ~.
catalyst indicated in Table One. After the run time, the polymer solution was
removed
from the reactor and quenched with isopropyl alcohol. A hindered phenol
antioxidant
(IRGANOXT"" 1010 (available from Ciba Geigy Corp.) was added to the polymer.
Volatiles were removed from the polymer in a reduced pressure vacuum oven at
135°C
for 20 hours.
The preparation conditions for the substantially random interpolymers are set
forth in Table 1.
Table 1
SampleCatalystISOPART""-EStyreneEthyleneHydrogenReactionReactionYield
amount (mL) (mL) (kPa) (kPa) Temp Time (g)
(!~-mol) (C) (m~)
ES-1 2.5 250 750 2068 0 80 10 32.3
ES-2 3.8 500 500 1379 0 80 10 28.8
ES-3 15.0 500 500 1379 689 60 30 166
The resultant substantially random interpolymers were characterized as being
pseudorandom and linear.
The interpolymers were compounded and cured according to the following
procedure. The 60 gram bowl of a Brabender PS-2 internal mixer was preheated
to
49°C. 100 pph carbon black N550 (available from Cabot Corporation), 50
pph
SLJNPART"" 2280 oil (available from Sun Oil), 5 pph paraffin wax, 1 pph
stearic acid, 8
pph Vul-Cup 40KE peroxide (available from Hercules) and 1.5 pph triallyl
cyanurate
coagent (available from American Cyanamid) were premixed in a plastic or paper
container. The resultant blend was loaded into the 60 gram bowl. To the bowl
was
further added 100 pph of the desired substantially random interpolymer as
prepared
above. The ram was lowered on the internal mixer, and the compound was allowed
to
mix until a temperature of 104°C was reached (approximately five
minutes). The
compound was removed from the mixer and was optionally roll-milled.
-49-
r~IVi'Efi~~~~~ SHEET
tPFR~c~
-. CA 02300062 2000-02-11
40874D
~ os ee~t ~~ ~~~~ ~~ ~e
a
~ a v v v v W a o a
~ ~ ~ ~ ~ ~ ~ ~ ~. a a
v v veav f ~c w s
The samples were compression molded at 127°C to obtain uncured
(green) test
plaques. The uncured (green) test plaques were compression mold cured at 171
°C for
20 minutes to obtain crosslinked thermoset elastomer compositions.
The stress-strain properties of the neat interpolymers, of the uncured (green)
test
plaques. and of the crosslinked thermoset elastomer compositions are set forth
in Table
2. Therein, the designation "ND" means that the given property was not
determined.
-50-
,p,~;E~~~_ :~~~ SHEET
IPFAIEP
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
Table 2
ES-1 ES-2 ES-3 C 1 C2 (V-457)=C3 (V-707)
* '
(Tafmer
680-P)'
COMONOMER CONTENT
(AS DIRECTED SY NMR)
wt % ethylene 67.5 56.8 48.0 51.0 70.0
wt % styrene 32.5 43.2 52.0 0 0
wt % propylene 0 0 0 49.0 30.0
STRESS-STRAIN PROPERTIES
OF NEAT UNCROSSLINKED
POLYMERS
tensile at break (psi)3200 2156 1390 668 243 887
100% modulus (psi) 759 445 256 170 75 205
elongation at break 395 420 518 I 115 1780 1336
(%)
melt index at 190C 0.8 0.8 10.2 4.0 7.1 3.9
(g/10 min)
Mw/Mn 2.07 2.14 3.50 21.8 3.07 4.59
GREEN STRESS-STRAIN
PROPERTIES
tensile at break (psi)ND ND 594 460 70 459
100% modulus (psi) ND ND 3 I 264 52 231
5
elongation at break ND ND 453 476 84 685
(%)
ES-1 ES-2 ES-3 C1* C2* C3*
(Tafmer
680-P}'(V-457)=(V-707)'
STRESS-STRAIN PROPERTIES
OF CROSSLINKED INTERPOLYMERS
tensile at break (psi)3156 ND 1005 1994 1236 1569
100% modulus (psi) 1076 ND 532 506 276 674
elongation at break 300 ND 297 383 409 292
(%)
* Not an example of the present invention.
As illustrated in Table 2, the crosslinked thermoset elastomer compositions of
the invention exhibit a higher 100 % modulus than the comparative materials C
1
-51-
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
(TafmerT"" 680-P (available from Mitsui Petrochemical)) and C2 (VistalonT"'
457
(available from Exxon Chemical Co.)). This was consistent with the
significantly
higher 100 % modulus exhibited by the neat interpolymers as compared to the
comparative materials.
Example 2 Preparation of Ethylene/Styrene/Ethylidene Norbornene
Interpolymers and Thermoset Elastomers
Ethylene/styrene/ethylidene norbornene interpolymers were made using (tert-
butylamido)dimethyl(tetramethyl-rls-cyclopentadienyl)silane
dimethyltitanium(+4)
catalyst and tris(pentafluorophenyl)borane cocatalyst in a one to one molar
ratio
according to the following procedure. A two liter reactor was charged with 360
grams
(500 mL) of ISOPART"" E mixed alkane solvent (available from Exxon Chemicals
Inc.)
and the desired amount of styrene comonomer. Ethylidene norbornene was
transferred
to the reactor. Hydrogen was added to the reactor by differential pressure
expansion
from a 75 mL addition tank. The reactor was heated to the run temperature and
was
saturated with ethylene at the desired pressure. (Tert-butylamido}dimethyl-
(tetramethyl-rls-cyclopentadienyl)silane dimethyltitanium (IV) catalyst and
tris(pentafluoro-phenyl)borane cocatalyst were mixed in a dry box by pipeting
the
desired amount of a 0.005 M solution of the tris(pentafluorophenyl)borane
cocatalyst in
ISOPART"" E mixed alkane solvent or toluene into a solution of the (tert-
butylamido)dimethyl-(tetramethyl-rls-cyclopentadienyl)silane dimethyl-titanium
(IV)
catalyst in ISOPART"" E mixed alkane solvent or toluene. The resulting
catalyst
solution was transferred to a catalyst addition tank and was injected into the
reactor.
The polymerization was allowed to proceed, with ethylene being introduced on
demand. Additional charges of catalyst and cocatalyst, if used, were prepared
in the
same manner and were added to the reactor periodically. The total amount of
catalyst
employed was reported in Table Three. In each instance, the amount of
tris(pentafluoro-phenyl)borane cocatalyst (on a molar basis) was equal to that
of the
(tent-butylamido)dimethyl-(tetramethyl-r)5-cyclopentadienyI)silane
dimethyltitanium
(IV) catalyst as indicated in Table Three. After the run time, the polymer
solution was
-52-
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
removed from the reactor and quenched with isopropyl alcohol. A hindered
phenol
antioxidant (IRGANOXT"" 1010 (available from Ciba Geigy Corp.) was added to
the
polymer. Volatiles were removed from the polymer in a reduced pressure vacuum
oven
at 135°C for 20 hours.
The preparation conditions for the ethylene/styrene/ethylidene norbornene
interpolymers are set forth in Table 3.
-53-
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
.o o; c~
~ N M
~" b~,D_, ,r
c
O
w y O O O
~ N M M
c
c
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The resultant substantially random interpolymers were characterized as being
pseudorandom and linear.
The interpolymers were compounded and cured according to the following
procedure. The 60 gram bowl of a Brabender PS-2 internal mixer was preheated
to
49°C. 100 pph carbon black N550 (available from Cabot), 50 pph
SLJNPARTM 2280
oil (available from Sun Oil), 5 pph paraffin wax, 1 pph stearic acid, 5 pph
zinc oxide,
1.5 pph sulfur, and 0.5 pph Captax 2-mercaptobenzothiazole (available from R.
T.
Vanderbilt) were premixed in a plastic or paper container. The resultant blend
was
loaded into the 60 gram bowl. To the bowl was further added 100 pph of the
desired
..
- 10 interpolymer as prepared above. The ram was lowered on the internal
mixer. and the
compound was allowed to mix until a temperature of 104°C was reached
(approximately five minutes). The compound was removed from the mixer and was
optionally roll-milled.
The samples were compression molded at 127°C to obtain uncured (green)
test
plaques. The uncured (green) test plaques were compression mold cured at 171
°C for
minutes to obtain crosslinked thermoset elastomer compositions.
As between ESDM 1 (a)-(d), ESDM 1 (a) was prepared in accordance with the
above formulation. ESDM1(b)-(d) were likewise prepared in accordance with the
above formulation, except that in the case of ESDM1(b), 50 pph SUNDEX 750T oil
20 (available from Sun Oil), was used in place of the SIINPAR oil; in the case
of
ESDM1(c), 50 pph trioctyltrimelliate was used in place of the SLTNPAR oil; and
in
the case of ESDM1(d), 0.75 pph (rather than 1.5 pph) sulfur was employed.
Regarding the comparative materials, C4 was prepared using the formulation
provided above, with Vistalon 6505 EPDM (available from Exxon) being used in
place of the substantially random interpolymer. C5 was prepared using the
formulation provided above, with EPSyn 70A EPDM (available from DSM
Copolymer) being used in place of the substantially random interpolymer used
in the
present invention. C6(a) was prepared using the formulation provided above.
with
SBF 1500 styrene butadiene
-55-
~i~f~E~~~~i :~ ~HEE~'
~a~ ~IE~
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
rubber being used in place of the substantially random interpolymers and
Sundex 750T
oil (available from Sun Oil) being used in place of the SUNPAR oil. C6(b) was
prepared using the formulation provided above, except that SBR 1500 styrene
butadiene rubber was used in place of the substantially random interpolymer,
50 pph
(rather than 100 pph) NS50 carbon black was employed, 7 pph Sundex 750T oil
(rather
than 50 pph SUNPAR 2280 oil) was employed.
The stress-strain properties of the neat interpolymers, of the uncured (green)
test
plaques, and of the crossIinked thermoset elastomer compositions were set
forth in
Table Four. Therein, the abbreviation "ND" means that a given property was not
determined.
-56-
CA 02300062 2000-02-11
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57
AMCi'~:~.~-i~ S~iEET
~ r, r- n W- r1
40874D
CA 02300062 2000-02-11
N ~ ~ N
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-_ CA 02300062 2000-02-11
40874D
x
r'
M
00
c
z ~ z ~ z
z ~ z ~ z
z ~ z ~ z
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z ~ z ~ z
T 70
t~!~
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p,~~,:;:~.~t? SHEc'i'
. -. ~ w W f'1
CA 02300062 2000-02-11
WO 99110395 PCT/US98/17673
As illustrated in Table 4, the crosslinked thermoset elastomers of the
invention
typically exhibit a highly improved 100% modulus, as compared to comparative
materials C4 (VistalonTM 6505 EPDM (available from Exxon)), CS (EPSyn 70A
EPDM (available from DSM Copolymer)) and C6 (SBR 1500 styrene-butadiene
rubber).
As further illustrated in Table Four, the crosslinked thermoset elastomers of
the
invention typically exhibit a resistance to oil swell similar to that of
styrene-butadiene-
rubber, but superior to that of EPDM materials.
As further illustrated in Table Four, the crosslinked thermoset elastomers of
the
invention exhibit aging properties superior to those of styrene-butadiene
rubber. For
instance, upon aging at 250°F for 70 hours in an air oven, the
crosslinked
ethylene/styrene/ethylidene norbornene interpolymer exhibited increased
tensile at
break values and moderately decreased elongation at break values. In contrast,
upon
oven aging under the same conditions, the styrene-butadiene rubbers exhibited
decreased tensile at break values and significantly decreased elongation at
break values.
Thus, as illustrated in Table 4, the crosslinked ethylene/styrene/diene
thermoset
elastomers of the invention exhibit a resistance to oil swell characteristic
of styrene-
butadiene rubber without suffering the concomitant negative effects of heat
aging.
Example 3 Preparation of Thermoplastic Vulcanizates
The Brabender PS-2 or Haake internal torque mixer was preheated to
350°C.
The desired amount of Pro-fax 6524 isotactic polypropylene (available from
Himont
Incorporated) was added to the mixer, and was allowed to melt and to
homogenize.
Over one minute, the desired amount of the noncrosslinked substantially random
interpolymer was added. Thereafter, the process oil, antioxidant, stearic
acid, and
carbon black were added and mixed for one minute. The zinc oxide, sulfur,
benzothiazyldisulfide and methyl toads were added. Mixing occurs until the
torque
-60-
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
reaches a maximum and for at least 10 minutes total mix time. The resultant
thermoplastic vulcanizate was removed from the mixer.
In executing the above procedure, the formulations set forth in Table 5 were
employed. Unless otherwise indicated, all amounts were expressed in parts per
hundred, based on 100 parts of the elastomer.
-61-
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
fV N
4 ~ N O ~ ~ S ~ h M - d ...V1 ~ M 1~
I- U f- ~ c c
U U
a 'r ~ O N M ~ ~ h M - a ~.V1 ~ M r
'; U F, '" a 0
U U
O $ o g M - .~~n 'r?M n
.- - c o
0 00 ,n
N ~' 'tw o, o U n o M _. N ~ v, 'r'.M n
' ~ ~ 0 0
v O C~S O M .-. - V1
~ I~ ~ M 1~
... O O
M ~ ~ V1 ~ M l~
v1 O O
N
r W p o0 ~n
f- W v v o~ $ "o ",M - a '-.~ = 0 0
F-
0
U
6''0
C7
U
E
v v ~ Q
E a E m E U E
~> _g
y W
a o Q
m
v X 'a~ ::
. d E o m a
5
:ro ~ m ~e ~.~-.
47C a o_~ ~ _ p ~ H H
~ ~ ~ ~ O C a 9
a L ~ '~ g 'oO .~
a vW 'x W
0 c ,o~ w ~',Z h N ',t3
a o ~ V
a ~ ~~ ~ ~ H a ~ N
~"'!n ~ H N
-62-
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
Except in the case of TPV 1 (b), SunParTM 2280 (available from Sun Oil) was
employed as the process oil. For TPV 1 (b), trioctyltrimelliate was employed
as the
process oil.
The resultant thermoplastic vulcanizates were compression molded at
380°F.
Representative physical properties of the thermoplastic vulcanizates and of
comparative
thermoplastic vulcanizates C-TPV1 (made with Vistalon 6505 EPDM (available
from
Exxon}) and C-TPV2 (made with EPSyn 70A EPDM (available from DSM Rubber))
were set forth in Table 6. Therein, the abbreviation "ND" means that a given
property
was not determined.
-63-
*rB
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
N
G4 ~ oho~ ~ 00
(- r Op M z
U
G N ~ N ~ O
. ~ ~ M z
~.
U
a~ ~o N
O N ~ M
p
p
M
N U ~ a, M ~ n
> ~o
a
E~
M
_ _ _
a ~
N ~ ~ ~ 0
~D O 0
O~ N
O~OO d'
z
H
~ ~
h M M 0
z p
Q _ ~
.. r.,
a
a g ~ o
a~
3 ''
o o
a b N ~
, ~ N (
v /7
o N
y o tC ~ 'C
~
v C p ~
O N
~ ~ C
/1
~" a x
~
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CA 02300062 2000-02-11
WO 99/10395 PCTIUS98/17673
A comparison of TPV I (a) and TPV2(a) with comparative materials C-TPV 1
(made with Vistalon 6505 EPDM (available from Exxon)) and C-TPV2 (made with
EPSyn 70A EPDM (available from DSM Rubber)) indicates that the thermoplastic
vulcanizates of the invention exhibit a much greater resistance to oil swell
(under the
ASTM #2 test method) than the comparative materials without sacrificing
hardness
(Hardness Shore "A"). A comparison of these materials further indicates that
the
thermoplastic vulcanizates of the invention exhibit improved 100% modulus
values and
comparable tensile at break values, with respect to the comparative materials.
A comparison of TPV-2(b), TPV-2(c), and TPV-2(d) indicates that one can
adjust resistance to ASTM #2 oil swell and hardness values by adjusting the
ratio
between the polypropylene and the substantially random interpolymer. Namely,
as the
proportion of the polypropylene increases, the resistance to ASTM #2 oil swell
and
hardness likewise increase. Moreover, the effect of the added substantially
random
interpolymer was evident. In particular, the percent elongation at break of
the inventive
I 5 thermoplastic vulcanizates was many times greater than that of unmodified
isotactic
polypropylene, which exhibits a percent elongation at break of I 3 percent.
Example 4. Peroxide Modified ESI
Preparation of Polymers Used
Reactor Description
A 6 gallon (22.7 L), oil jacketed, Autoclave continuously stirred tank reactor
(CSTR) was employed as the reactor. A magnetically coupled agitator with
Lightning
A-320 impellers provided the mixing. The reactor ran liquid full at 475 psig
(3,275
kPa). Process flow was in the bottom and out the top. A heat transfer oil was
circulated through the jacket of the reactor to remove some of the heat of
reaction.
After the exit from the reactor was a micromotion flow meter that measured
flow and
solution density. All lines on the exit of the reactor were traced with 50 psi
(344.7 kPa)
steam and insulated.
-6s-
CA 02300062 2000-02-11
WO 99/10395 PCTNS98/17673
Procedure
Ethylbenzene solvent was supplied to the mini-plant at 30 psig (207 kPa). The
feed to the reactor was measured by a Micro-Motion mass flow meter. A variable
speed diaphragm pump controlled the feed rate. At the discharge of the solvent
pump,
a side stream was taken to provide flush flows for the catalyst injection line
( 1 lblhr
(0.45 kg/hr)) and the reactor agitator (0.75 lb/hr ( 0.34 kg/ hr)). These
flows were
measured by differential pressure flow meters and controlled by manual
adjustment of
micro-flow needle valves. Uninhibited styrene monomer was supplied to the mini-
plant
at 30 psig (207 kpa). The feed to the reactor was measured by a Micro-Motion
mass
flow meter. A variable speed diaphragm pump controlled the feed rate. The
styrene
streams was mixed with the remaining solvent stream. Ethylene was supplied to
the
mini-plant at 600 psig (4,137 kPa). The ethylene stream was measured by a
Micro-
Motion mass flow meter just prior to a Research valve controlling flow. A
Brooks flow
meterlcontroller was used to deliver hydrogen into the ethylene stream at the
outlet of
the ethylene control valve. The ethylene/hydrogen mixture combines with the
solvent/styrene stream at ambient temperature. The temperature of the
solvent/monomer as it enters the reactor was dropped to ~5 °C by an
exchanger with
-5°C glycol on the jacket. This stream entered the bottom of the
reactor. The three
component catalyst system and its solvent flush also entered the reactor at
the bottom
but through a different port than the monomer stream. Preparation of the
catalyst
components took place in an inert atmosphere glove box. The diluted components
were
put in nitrogen padded cylinders and charged to the catalyst run tanks in the
process
area. From these run tanks the catalyst was pressured up with piston pumps and
the
flow was measured with Micro-Motion mass flow meters. These streams combined
with each other and the catalyst flush solvent just prior to entry through a
single
injection line into the reactor.
Polymerization was stopped with the addition of catalyst kill (water mixed
with
solvent) into the reactor product line after the micromotion flow meter
measuring the
solution density. Other polymer additives can be added with the catalyst kill.
A static
CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
mixer in the line provided dispersion of the catalyst kill and additives in
the reactor
effluent stream. This stream next entered post reactor heaters that provided
additional
energy for the solvent removal flash. This flash occurred as the effluent
exited the post
reactor heater and the pressure was dropped from 475 psig (3,275 kPa) down to
~250mm of pressure absolute at the reactor pressure control valve. This
flashed
polymer entered a hot oil jacketed devolatilizer. Approximately 85 percent of
the
volatiles were removed from the polymer in the devolatilizer. The volatiles
exited the
top of the devolatilizer. The stream was condensed with a glycol jacketed
exchanger,
entered the suction of a vacuum pump and was discharged to a glycol jacket
solvent
and styrene/ethylene separation vessel. Solvent and styrene were removed from
the
bottom of the vessel and ethylene from the top. The ethylene stream was
measured
with a Micro-Motion mass flow meter and analyzed for composition. The
measurement of vented ethylene plus a calculation of the dissolved gasses in
the
solventlstyrene stream was used to calculate the ethylene conversion. The
polymer
separated in the devolatilizer was pumped out with a gear pump to a ZSK-30
devolatilizing vacuum extruder. The dry polymer exited the extruder as a
single strand.
This strand was cooled as it was pulled through a water bath. The excess water
was
blown from the strand with air and the strand was chopped into pellets with a
strand
chopper.
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WO 99/10395 PCT/US98/17673
Catalysts Employed
TitaniumBoron MMAOe
CompoundCompound
Type Type Boron/fiAI/1'I
Ratio Ratio
ESI-4 A8 Ae 1.25;1 12.0:1
ESI-5 Bb A~ 1.26:1 8.0:1
ESI-6 Bb Ae 1.25:1 10.0:1
ESI-7 Bb A~ 1.25:1 10.0:1
ES1-8 Bb A~ 1.24:1 10.0:1
ESI-9 Ae A~ 1.251 10.01
ESl-10 Bb Bd 2.98:1 7.0:1
ESl-11 Bb Bd 3.011 7.01
ESI-12 Bb Bd 3.491 9.01
ESI-13 Bb Ae 1.25:1 10.0:1
ESI-14 A8 A~ 1.25:1 9.9:1
ESI-IS Aa A~ 1.24:1 12.0:1
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WO 99/10395 PCTNS98/1?673
a (t-butylamido)dimethyl(tetramethylcyclopentadienyl)silane-titanium
(II) 1,3-pentadiene.
b dimethyl(N-(1,1-dimethylethyl)-1,1-dimethyl-1-((1,2,3,4,5-.eta.)-
1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl]silanaminato(2-)-N]-
titanium.
c bis-hydrogenated tallowalkyl methylammonium
tetrakis(pentafluorophenyl)borate.
d tris(pentafluorophenyl)borane. a a modified methylaluminoxane
commercially available from Akzo Nobel as MMAO-3A.
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WO 99/10395 PCT/US98/17673
Reactor Data
Polymer ReactorSolv. Ethylene Hydr-StyreneFlow Vent
Temp.
Flow Flow ogen Conv.
Flow
C lb/hrkg/hrIb/hr kg/hrSCCM Ib/hrkg/hr
ESI-4 65.5 8.8 3.99 0.81 0.374.5 13.05.90 87.26
ESI-5 71.4 11.45.17 1.21 0.559.0 14.06.35 87.79
ESI-6 80.3 18.68.44 1.69 0.7712.0 12.05.44 88.18
ESI-7 86.7 28.913.112.48 1.1217.0 9.7 4.40 92.43
ESI-8 90.4 30.113.662.90 1.3221.0 8.9 4.04 92.06
ESI-9 101.9 19.28.72 1.99 0.904.0 7.0 3.18 87.72
ESI-10 90.9 40.018.163.13 1.4216.0 5.3 2.41 95.72
ESI-11 89.9 25.611.622.06 0.949.0 4.3 1.95 96.71
ESI-12 79.4 41.018.612.18 0.996.0 16.57.49 94.91
ESI-13 79.7 18.68.44 1.70 0.7711.7 12.05.44 88.6
ESI-14 69.2 2.921.32 1.0 0.450 20.09.07 86.3
ESI-15 65.0 8.8 3.99 0.80 0.364.5 13.05.90 88.7
Table 7 lists the characteristics of the polymers used in this study.
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CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
Table 7
Polymers Used
Lot No. DescriptionIZ' I,/IZ TotalAtactic
StyrePS
(~10 ne
min) (%) (%)
ESI-4 74% S 1.44 8.8 58.4 15.5
ESI
ESI-S 67% S 1.10 9.0 51.2 15.3
ESI
ESI-6 60% S 1.11 7.5 56.4 3.4
ESI
ESI-7 54% S 1.72 6.6 52.3 1.5
ESI
ESI-8 45% S 1.08 7.7 43.4 1.3
ESI
ESI-9 33% S 1.22 7.6 26.4 6.2
ESI
ESI-10 41 1.3 --- 41.0 0.3
ESI-11 S1 1.2 --- 50.0 0.6
ESI-12 73 1.2 --- 69.1 1.7
ESI-13 58% S I.0 --- --- 3
ESI
ESI-14 73.4% 5.0 --- --- 8.6
S ESI
ESI-I 68.5% 1.05 9.0 --- 16.9
S S ESI
POE Affinity 1 --- --- -__
EG
8100*
a As determined by ASTM D 1238 cond. I.
b An ethylene-octene copolymer having a melt index of 1 g/10 min. (as
determined by ASTM D 1238 cond. I) and a density of 0.870 g/cc (as
CA 02300062 2000-02-11
WO 99/10395 PGT/US98/17673
determined by ASTM D 792) commercially available from The Dow
Chemical Company.
Formulation Processing Conditions
Formulations with above polymers were prepared with 3, 6 and 9 wt % dicumyl
peroxide (DiCup manufactured by Hercules Inc.). Formulations were prepared in
a
Hakke Rheocord 9000 equipped with a 50 g mixing bowl under the following
conditions: 120°C, 50 RPM, 10-12 minutes mixing time.
Formulation Curin;e Conditions
Samples were crosslinked at 170°C for 20 minutes, using 200 pounds of
force in
a compression molding press (Tetrahedron Press Model-MTP-8).
Results
Table 8 summarizes results for gel content and upper service temperature for
the
peroxide crosslinked ESI samples. The results in Table 8 indicate that
peroxide can be
used to crosslink ESI. The degree of crosslinking was measured by gel content
analysis. All the peroxide modified samples have gel content greater than 60%.
The
upper service temperature increased significantly when the samples were
treated with
peroxide. Figure 1 shows the graph of expected and actual gel content vs.
styrene
composition for the ESI samples treated with 9% peroxide. The measured gel
content
is much higher than the expected value. These are unexpected results since the
reactivity of ESI toward peroxide is similar to polyethylene rather than a
copolymer of
styrene and ethylene.
-72-
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WO 99/10395 PCT/US98/17673
Table 8
Peroxide Crosslinking of Ethylene Styrene Interpolymers
Sample PolymerDescription %Gel Upper Service
No. Temperature
(C)
ESI-9 33% S ESI-0% Peroxide0 86.0
B 6SI-8 45% S ESI-0% Peroxide0 50.0
C ESI-7 54% S ESI-0% Peroxide0 50.0
D ESI-6 60% S ESI-0% Peroxide0 50.0
E ESI-5 67% S ESI-0% Peroxide0 60.0
F ESI-4 74% S ESI-0% Peroxide0 68.0
G POE Affinity EG 8100-0% 0 68.0
Peroxide
H x- 33% S ESI-3% Peroxide88.6 >185
LINKEDE
SI-9
1 x-LINKED45% S ESI-3% Peroxide93.0 165.0
ESI-8
J x-LINKED54% S ESI-3% Peroxide79.3 >185
ESI-7
K x-LINKED60% S ESI-3% Peroxide82.2 179.0
ESI-6
L x-LINKED67% S ESI-3% Peroxide68.6 170.0
ESI-5
M ESI-4 74% S ESI-3% Peroxide63.5 97.0
N* x-LINKEDAffmity0 EG 8100-3% 97.3 >185
Peroxide
POE
O x- 33% S ESI-6% Peroxide94.6 >185
LINKEDE
SI-9
P x-LINKED45% S ESI-6% Peroxide90.5 >185
ESI-8
Q x-LINKED54% S ESI-6% Peroxide92.0 >I85
ESI-7
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CA 02300062 2000-02-11
WO 99110395 PCT/US98/17673
Table 8 continued
R x-LINKED60% S ESI-6% Peroxide92.6 >185
ESI-6
S x-LINKED67% S ESI-6% Peroxide85.5 >185
ESI-5
T x-LINKED74% S ESI-6% Peroxide75.3 >185
ESI-4
U* x-LINKEDAffinity0 EG 8100-6%99.4 >185
Peroxide
POE
V x- 33% S ESI-9% Peroxide94.9 >185
LINKEDE
SI-9
W x-LINKED45% S ESI-9% Peroxide93.5 > 185
ESI-8
X x-LINKED54% S ESI-9% Peroxide92.6 >185
ESI-7
Y x-LINKED60% S ESI-9/o Peroxide91.5 >185
ESI-6
Z x-LINKED67% S ESI-9% Peroxide89.0 >185
ESI-5
AA x-LINKED74% S ESI-9% Peroxide80.7 >185
ESI-4
AB* x-LINKEDAtlinity0 EG 8100-9%97.8 >185
Peroxide
POE
* Not an example of the present invention.
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WO 99/10395 PCT/US98/17673
Peroxide Modified ESI Blends
Polymers Used
Table 9 summarizes ESI samples used for this study.
Table 9
Polymers Used
Polymer Description
ESI-9 33% S ESI
ESI-4 74% S ESI
POE Affinity EG 8100
SBS Vector 2518 Styrenic
Block
Copolymer*
* A styrene-butadiene-styrene block copolymer containing 30 % styrene by
weight
having a melt index of 1 g/10 min. (as determined by ASTM D 1238 cond. I)
commercially available from Dexco .
Formulation Processing Conditions
Formulations with the above polymers were prepared with 4 wt % dicumyl
peroxide (DiCup manufactured by Hercules Inc.). Formulations were prepared in
a
Haake Rheocord 9000 equipped with a 50 g mixing bowl under the following
conditions: 120°C, SO RPM, 10-12 minutes mixing time.
Formulation Curing Conditions
Samples were crosslinked at 170°C for 20 minutes, under 200 pounds
of force
in a compression molding press {Tetrahedron Press Model-MTP-8).
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WO 99/10395 PCT/US98/17673
Results
Table 10 summarizes the blends of ESI prepared with AFFINITY EG 8100 and
SBS to determine the effect of blending a polyolefin elastomer or a
styrene/butadiene/styrene polymer on the crosslinlcing efficiency of ESI
copolymers.
Table 10
Blend Properties
Description Gel
Sample
No.
A ESl-9 (33% S) 0
B ESI-9 (33% S) + 4% DCP 83.8
C ESI-9 (33% S)+10% SBS+4% 87
DCP
D ESI-9 (33% S)+10% POE+4% 81.1
DCP
E ESI-4 (74% S) 0
F ESI-4 (74% S)+4% DCP 64.5
G ESI-4 (74% S)+10% SBS+4% 71.5
DCP
H ESI-4 (74% S)+10% POE+4% 59.6
DCP
* Not an example of the present invention.
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WO 99/10395 PCT/US98/17673
Addition of SBS increased the gel level for both of the ethylene/styrene
interpolymers studied.
E-Beam Radiated Substantiallv Random Interoolymers
The same polymers as listed in Table 7 were used for this study.
Formulation Preparation and Curing Conditions
Compression molded plaques were treated with 5, 10, 15 and 20 Mrad of e-
beam radiation.
Results
The results in Table 11 indicate that E-beam radiation can be used to
crosslink
ESI, that is, the radiation increases the gel content and upper service
temperature. It is
observed that the E-beam radiated samples (R, Q, and P) are much less sticky
than the
unmodified samples (C, D, and E). The effect of low radiation dose on
I,°/Iz ratio was
measured for 74% S ESI sample radiated with 5 Mrad dosage: the I,°/IZ
ratio for non-
treated sample was 8.8 and for 5 Mrad dosage was 12.3.
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CA 02300062 2000-02-11
WO 99/10395 PGT/US98/17673
Table 11
E-beam Crosslinking of Ethylene Styrene Interpolymers
Sample Description %Gel Upper Service
Temperature
No. (C)
A ESI-9 (33% S)-0 Mrad 0 86
B ESI-8 (45% S)-0 Mrad 0 50
C ESI-7 (54% S~0 Mrad 0 50
D ESI-6 (60% S~0 Mrad 0 56
E ESI-5 (67% S)-0 Mrad 0 60
F ESI-4 (74% S)-0 Mrad 0 68
G* A~nityT"' EG 8100-0 0 68
Mrad
H 33% S ESI-5 Mrad 0.1 88
I 45% S ESI-5 Mrad 0 56
J 54% S ESI-5 Mrad 1.8 56
K 60% S ESI-5 Mrad 0.3 60
L 67% S ESI-5 Mrad 0.4 64
M 74% S ESI-5 Mrad 0.4 72
N* AffinityT"' EG 8100-5 0.3 73
Mrad
O ESI-9 (33% S)-10 Mrad - -
P ESI-8 (45% S)-10 Mrad 1.3 62
Q ESI-7 (54% S)-10 Mrad 0.1 64
R ESI-6 (60% S~10 Mrad 0.4 68
S ESI-5 (67% S)-10 Mrad O.I 74
T ESI-4 (74% S)-10 Mrad 0.2 80
U* AffmityT"' 8100-10 Mrad76.3 77
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CA 02300062 2000-02-11
WO 99/10395 PCT/US98/17673
Table 11 continued
V ESI-9 (33% S)-IS Mrad 62.2 98
W ESI-8 (45% S)-IS Mrad 68 80
X ESI-7 (54% S)-IS Mrad 65 72
Y ESI-6 (60% S)-15 Mrad 44.6 70
Z ESI-5 (67% S)-15 Mrad 8.2 74
AA ESI-4 (74% S)-15 Mrad 1.2 77
AB* AffinityT"' EG 8100-IS 82.3 96
Mrad
AC ESI-9 (33% S)-20 Mrad 70 125
AD ESI-8 (45% S)-20 Mrad 70.4 94
AE ESI-7 (54% S)-20 Mrad 75.2 92
AF ESI-6 (60% 520 Mrad 67.1 80
AG ESI-5 (67% S)-20 Mrad 55.3 80
AH ESI-4 (74% S)-20 Mrad 21.2 80
AI* AftinityT"' 8100-20 Mrad90.2 186
* Not an example of the present invention.
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Silane Modified Substantially Random Interpolymers
Materials Used
Table 12 summarizes the materials used for this study.
Table 12
Polymers Used
Polymer No. Description
ESI-10 41% S ESI
ESI-11 S I % S ESI
ESI-12 73% S ESI
POE Affinity 8100
Formulation Preparation Conditions
Table 13 shows formulations prepared for the silane crosslinking study.
Table 13
Formulations for ESI Silane Crosslinking Study
41% Styrene51% 73% StyreneAmity Vinyl DicumylDibutyl
Styrene EG Tri-
ESI-10 ESI-11 ESl-l2 8100 methoxyPeroxide
tin
Dilaur
wt. % wt. wt. % wt. Silanewt.
% %
ate
Wt.
wt.
97.85 0 0 0 2 0.15 0.02
97.7 0 0 0 2 0.30 0.02
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Table 13 continued
95.85 0 0 0 4 0.15 0.02
95.7 0 0 0 4 0.30 0.02
0 97.85 0 0 2 0.15 0.02
0 97.7 0 0 2 0.30 0.02
0 95.85 0 0 4 0.15 0.02
0 95.7 0 0 4 0.30 0.02
0 0 97.85 0 2 0.15 0.02
0 0 97.7 0 2 0.30 0.02
0 0 95.85 0 4 0.15 0.02
0 0 95.7 0 4 0.30 0.02
0 0~ 0 97.85 2 0.15 0.02
0 0 0 95.85 4 0.15 0.02
The Samples were extruded on a Haake Polylab Polymer Processing unit
equipped with a 18 mm twin screw extruder, pelletizer and water bath with air
knife.
Samples were prepared in a two step process:
Step 1: Silane was grafted onto the polymer using the following procedure:
~ Appropriate ratio solution of vinyltrimethoxy silane and dicumyl peroxide
was
liquid injected into the extruder barrel along with the polymer
~ Conditions: 200°C melt temperature, 50 rpm
Step 2: Addition of the dibutyltin dialurate catalyst
~ A 2% concentrate of the catalyst was made in each of the polymers studied.
The
catalyst concentrate pellets were dry blended with silane grafted material
from Step
1 and extruded at 200°C at 50 rpm.
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The results in Table 14 indicates that silane chemistry can be used to prepare
crosslinked ESI by a moisture cured process. ESI was grafted with vinyl
siloxane
which acts as a moisture cured reactive site. The Gel content in the range of
40 to 65
was achieved for ESI with the styrene compositions from 41 to 51 %.
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Table 14
Silane Crosslinking of Ethylene Styrene Interpolymers
Sample Description %Gel Upper Service
Temperature
No. (C)
A ESI-10 (41% S), 1500 ppm DCP, 45.6 55.2
2% VTMOS
B ESI-10 (41% S), 3000 ppm DCP, 65.3 55.1
2% VTMOS
C ESI-10 (41% S), 1500 ppm DCP, 57.0 55.1
4% VTMOS
D ESI-10 (41% S), 3000 ppm DCP. 44.3 55.1
4% VTMOS
E ESI-11 (51% S), 1500 ppm DCP, 45.8 47.3
2% VTMOS
F ESI-11 (51% S), 3000 ppm DCP, 57.6 49.3
2% VTMOS
G ESI-1 I (51% S), 1500 ppm DCP,64.8 49.5
4% VTMOS
H ESI-11 (51% S), 3000 ppm DCP, 46.8 49.3
4% VTMOS
I ESI-12 (73% S), 1500 ppm DCP, 0.4 59.7
2% VTMOS
J ESI-12 (73% S), 3000 ppm DCP, 0.3 61.6
2% VTMOS
K ESI-12 (73% S), 1500 ppm DCP, 0.1 61.4
4% VTMOS
L ESI-12 (73% S), 3000 ppm DCP. 1.0 59.9
4% VTMOS
M* Affinity EG 8100 8100, 1500 87.5 92.4
ppm DCP, 2% VTMOS
N* Affinity 8100EG 8100, 1500 93.9 >185
ppm DCP, 4% VTMOS
* Not an example of the present invention.
AZIDE MODIFIED ESI
Test methods and equipment used in the preparation and testing of the
following
Samples 1-10.
Test Methods:
A Rheometrics Inc. RDA-II dynamic mechanical spectrometer was used to
obtain DMS data. A temperature sweep was run from approximately -70°C
to 300°C at
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5°C/step with 30 s equilibration delay at each step. The oscillatory
frequency was 1
radians with an autostrain function of 0.1 % strain initially, increasing in
positive 100%
adjustments whenever the torque decreased to 4 g-cm. The maximum strain was
set at
26%. The 7.9-mm parallel plate fixtures were used with an initial gap of 1.5
mm at
160°C (the sample was inserted into the RDA-II at 160°C). The
"Hold" function was
engaged at 160°C and the instrument was cooled to -70°C and the
test started. (The
Hold function corrects for the thermal expansion or contraction as the test
chamber is
heated or cooled.) A nitrogen environment was maintained throughout the
experiment
to minimize oxidative degradation.
DSC (Differential Scanning Calorimetry) data were obtained using a Perkin-
Elmer DSC-7. Samples were melt-pressed into thin films and put in aluminum
pans.
The samples were heated to 180°C in the DSC and kept there for 4 min to
ensure
complete melting. The samples were then cooled at 10°C/min to -
30°C and heated to
140°C at 10°C/min.
A Perkin Elmer model TMA 7 thermomechanical analyzer was used to measure
the upper service temperature. Probe force of 102g and heating rate of
5°C/min were
used. Test specimen was a disk with thickness of about 2mm and diameter,
prepared
by compression molding at 205°C and air-cooling to room temperature.
General procedures for determining compression set are described in ASTM D
395-89. The sample plaques were cut into disks of 1.14 inch diameter. The
disks were
stacked up to a thickness of 0.5 inch. Test specimens were measured under
constant
strain of 25%, at 70°C for 22 h. The sample was aged at 70°C for
22 h under 25%
compression, cooled to 22°C.
Xylene Extraction was performed by weighing out I gram samples of the
polymer. The samples were transferred to a mesh basket which was then placed
in
boiling xylene for 12 hours. After 12 hours, the sample baskets were removed
and
placed in a vacuum oven at 150°C and 28 in. of Hg vacuum for 12 hours.
After 12
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hours, the samples were removed, allowed to cool to room temperature over a 1
hour
period, and then weighed. The results were reported as percent polymer
extracted.
extracted = (initial weight-final weight)/initial weight.
40 Tensile properties were determined by compression molding 1/16 inch
plaques.
Tensile specimens were then cut from these plaques and tested on an Instron
Tensile
tester.
Samples were prepared using either a HaakeBuchler Rheomix 600 mixer with
roller style blades, attached to a HaakeBuchler Rheocord 9000 Torque
rheometer, or
45 using a Brabender mixer (Type R.E.E. No. A-19/S.B) with a 50 g mixing bowl.
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Preparation of 4.4'-disulfonvlazidophenyl ether
4.4'-bis(chlorosulfonyl)phenyl ether (lOg, 0.027 mole) was dissolved in 100 mL
of acetone and 4.426 g (0.06808 moles) of solid sodium azide was added
portionwise
over the course of 15 minutes. The reaction mixture was stirred for 26 hours
at ambient
temperature and then was filtered to remove sodium chloride. The filter cake
was
washed with acetone and the combined f ltrate evaporated to yield a white
solid which
was washed twice with 20 mL portions of water and then dried at ambient
temperature
under vacuum. The resulting white solid (7.3 g, 70%) was identified as 4,4'-
disulfonylazidophenyl ether by 1H and 13C NMR spectroscopy.
Crosslinkin og-f Ethylene-Styrene Interpol mers
Ethylene-styrene copolymer (40 g) containing 58 wt % styrene (ESI-3831-
960921-1100) (3 wt % atactic polystyrene, 1.0 MI) was dry blended with 0.2 g
(0.5
weight percent, 0.55 mmole) of 4,4'-disulfonylazidobiphenyl in a plastic bag.
The
blend was added to a Brabender mixer (Type R.E.E. No. A-19/S.B) at
120°C (60 rpm)
with a 40 g mixing bowl. The mixture was blended at 120°C for 3 minutes
and then
removed from the mixer and allowed to cool yielding 38.9 g of blend 1.
The above blending experiment was repeated with 0.4 g ( 1.0 weight percent,
1.1
mmole) of 4, 4'-disulfonylazidobi-phenyl to yield blend 2, and 0.8 g (2.0
weight
percent, 2.2 mmole) of 4, 4'-disulfonylazidobiphenyl to yield blend 3.
The above blending experiment was repeated with 0.8 g (2 weight percent) of
1,3-disulfonylazidobenzene to yield 39.3 g of blend 4, and 0.8 g (2.0 weight
percent) of
1,3,5-trisulfonylazidobenzene to yield 39.1 g of blend 5.
Blends 1-5 and uncrosslinked ESI-13 which is the untreated starting material
were then compression molded at 120°C and 20,000 lb force for 3
minutes, followed by
curing at 190°C and 20,000 lb for l0 minutes, followed by cooling to
80°C over 5
minutes while still under pressure. All of the samples were characterized by
TMA
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analysis and select samples were characterized by xylene extraction and DMS
measurements. This data shows that at 2% sulfonyl azide, the samples are
completely
crosslinked. Crosslinked Blends 1-5 are referred to as Samples 1-5
respectively.
Sample UST (TMA)% Xyiene G' (20C) G' (200C)
C Extract.
ESI-13 52 99 3.OE'' 3.OE'3
1 64 12 Data Not measured
2 106 2 Data Not measured
3 >190 2 Data Not measured
4 > I 90 0 8.OE'' 3.OE~
>190 2 Data Not measured
5
Sample Toughness Break %ElongationCompression
Stress set
(In-Lb/Cu.In)(PSI) (70 C)
ESI-13 2450 41 1 900 64%
3 4000 1700 650 17%
4 4700 2000 630 7%
5 4300 1700 630 16%
The following example shows crosslinking of a high styrene ESI (St
wt%>50%), which is important for illustrating why crosslinking with
difunctional
azides is preferred over peroxide crosslinking.
A Haake Rheocord 9000 equipped with a 50 g mixing bowl was heated to
120°C. 40.0 g of ESI (3831-960710-1500) (73.4% Copolymer Styrene, 8.6%
atactic
polystyrene, @ 5.0 MI) was added to the mixing bowl. After 1 minute, 0.8 g
(2.0
weight percent) of 1,3-disulfonylazidebenzene was added to the mixing bowl and
the
sample was compounded for 3 more minutes. The polymer was removed from the
Haake and compression molded at 120°C and 20,000 lb force for 3
minutes. The
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sample was then cured at 180°C and 20,000 lb for 10 minutes followed by
cooling to
80°C over 5 minutes to yield Sample 6. Untreated ESI-14 was not treated
with
poly(sulfonyl azide) but was molded and cured as was Sample 6.
Sample UST (TMA) Compression set
C (70C)
ESI-14 60 97%
6 >190 15%
The results from Samples 1-6 demonstrate that disulfonyl azide can be used to
prepare coupled, partially crosslinked, and fully crosslinked ESI. Samples 2-4
are fully
crosslinked polymers. The toughness and the upper service temperature of
crosslinked
ESI using the disulfonyl azide are much better than that of the uncrosslinked
ESI.
PREPARATION OF PEROXIDE CROSSLINKED ESI FOR COMPARISON WITH
AZIDE CROSSLINKED ESI
Samples 7 & 8
A Haake Rheocord 9000 equipped with a 50 g mixing bowl was heated to
120°C. 48.5 g of ESI 6 (57.7% copolymer styrene, 3.3% homopolymer
Polystyrene,
1 S 1.02 Mi, 7.8 h°/Iz) was added and mixed at 50 RPM. After 6 minutes,
1.5 g (3.0 wt%)
of Dicumylperoxide (Hercules Inc.) was added and the sample was compounded for
6
more minutes. The sample was removed from the Haake and compression molded at
120°C and 20,000 lb force for 3 minutes, then cured at I70°C for
20 minutes, 200 lb
(90.78 kg) force in a compression molding press (Tetrahedron Press Model-MTP-
8).
This was Sample 7. In Sample 8, the procedure was repeated using 47.0 g of ESI-
6
and 3.0 g of dicumylperoxide (6 wt%). Tensile properties, compression set and
UST by
TMA were measured.
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Samples 9 & 10
A Haake Rheocord 9000 equipped with a 50 g mixing bowl was heated to
120°C. 48.5 g of ESI-15 (68.5% copolymer styrene, 16.9% homopolymer
Polystyrene,
1.05 Mi, 9.0 I10/I2) was added and mixed at 50 RPM. After 6 minutes, 1.5 g
(3.0 wt%)
of Dicumylperoxide (Hercules Inc.) was added and the sample was compounded for
6
more minutes. The sample was removed from the Haake and compression molded at
120°C and 20,000 lb (9078.48 kg)force for 3 minutes and then cured at
170°C for 20,
200 lb (90.78 kg) force in a compression molding press (Tetrahedron Press
Model-
MTP-8). This was Sample 9. In Sample 10, the procedure was repeated using 47.0
g
of ESI-15 and 3.0 g of dicumylperoxide (6 wt%). Tensile properties,
compression set
and UST by TMA were measured.
Sample weight weight % Break CompressioUST
% % elongationStress n Set (TMA- Gel
peroxide Azide (PSI) (70C) C)
3 --- 2.0 650 2000 17% >190 98
7 3 --- 630 890 33% 179 82
8 6 --- 360 880 8% >l90 93
6 --- 2.0 310 2300 17% >190 98
9 3 --- 320 1800 64% 97 64
10 6 --- 310 1300 32% > 190 81
Samples 3, and 6 show that cross-linking of ESI with difunctional
sulfonylazide
compounds represents an improvement over peroxide crosslinked ESI (Samples 7,
8, 9
and 10).
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