Note: Descriptions are shown in the official language in which they were submitted.
CA 02409696 2002-11-05
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Hydrogenated Vinyl Aromatic-Diene-Nitrile Rubber
The present invention relates to polymers that are
composed of a vinyl aromatic compound, a conjugated dime and a
nitrite and that have been selectively hydrogenated to reduce
ethylenic carbon-carbon double bonds without concomitant
reduction of aromatic carbon-carbon double bonds and nitrite
groups. The invention also relates to a process for
selectively hydrogenating such a polymer.
Backaround of the Invention
Polymers formed by polymerisation of a vinyl aromatic
monomer, a conjugated dime and an unsaturated nitrite are
known. These polymers contain ethylenic carbon-carbon double
bonds. Such polymers, composed of styrene, 1,3-butadiene and
acrylonitrile, are commercially available from Bayer under the
trademarks Krylene VPKA 8802 and Krylene VPKA 8683. A process
has been found for the selective hydrogenation of the ethylenic
carbon-carbon double bonds. It has also been found that the
product of the selective hydrogenation differs surprisingly
from the unhydrogenated polymer in several valuable properties.
Summary of the Invention
In one aspect the invention provides a polymer of a
conjugated dime, an unsaturated nitrite and a vinyl aromatic
compound that has been selectively hydrogenated to reduce
ethylenic carbon-carbon double bonds without hydrogenating
nitrite groups and aromatic carbon-carbon double bonds.
In another aspect the invention provides a process
which comprises selectively hydrogenating a polymer of a
conjugated dime, an unsaturated nitrite and a vinyl aromatic
compound to reduce ethylenic carbon-carbon double bonds without
concomitant reduction of nitrite groups and aromatic carbon-
carbon double bonds.
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Description of Preferred Embodiments
Many conjugated dimes are used in nitrile rubbers
and these may all be used in the present invention. Mention is
made of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,
1,3-pentadiene and piperylene, of which 1,3-butadiene is
preferred.
The nitrite is normally acrylanitrile or
methacrylonitrile or a-chloroacrylonitrile, of which
acrylonitrile is preferred.
The vinyl aromatic compound can be, for example,
styrene, a-methylstyrene or a corresponding compound bearing an
alkyl or a halogen substituent, or both, on the phenyl ring,
for instance, a p-C1-C6 alkylstyrene such as p-methylstyrene or
a bromo-substituted p-methylstyrene.
The conjugated dime usually constitutes about 50 to
about 75% of the polymer, the nitrite usually Constitutes about
10 to 500, preferably about 10 to 30% of the polymer and the
vinyl aromatic compound about 5 to about 30%, preferably 10 to
20%, these percentages being by weight. The polymer may also
contain an amount, usually not exceeding about 10%, of another
copolymerisable monomer, for example, an ester of an
unsaturated acid, say ethyl, propyl or butyl acrylate or
methacrylate, or a carboxylic acid, for example acrylic,
methacrylic, ethacrylic, crotonic, malefic (possibly in the form
of its anhydride), fumaric or itaconic acid. The polymer
preferably is a solid that has a molecular weight in excess of
about 100,000, most preferably in excess of about 200,000.
The polymer that is to be hydrogenated can be made in
known manner, by emulsion or solution polymerisation, resulting
in a statistical polymer. The polymer will have a backbone
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composed entirely of aliphatic carbon atoms. It will have some
vinyl side-chains, caused by 1,2-addition of the conjugated
dime during the polymerisation. It will also have ethylenic
double bonds in the backbone from 1,4-addition of the dime.
Some of these double bonds will be in the cis and some in the
trans orientation. These ethylenic carbon-carbon double bonds
are selectively hydrogenated by the process of the invention,
without concomitant hydrogenation of the nitrile and aromatic
carbon-carbon double bonds present in the polymer.
The preferred vinyl aromatic compound is styrene and
the preferred conjugated dime is butadiene. The invention
will be described, by way of example, with reference to
styrene-butadiene-nitrite rubber (SNBR) and to hydrogenated
styrene-butadiene-nitrite rubber (HSNBR) but it should be
appreciated that the description applies also to rubber in
which the vinyl aromatic compound is other than styrene and the
conjugated dime is other than butadiene, unless the context
requires otherwise.
The selective hydrogenation can be achieved by means
of a rhodium-containing catalyst. The preferred rhodium
catalyst is of the formula:
(RmB)lRhXn
in which each R is a C1-Cg-alkyl group, a C4-C$-cycloalkyl group
a C6-C15-aryl group or a C~-C15-aralkyl group, B is phosphorus,
arsenic, sulfur, or a sulphoxide group S=0, X is hydrogen or an
anion, preferably a halide and more preferably a chloride or
bromide ion, 1 is 2, 3 or 4, m is 2 or 3 and n is 1, 2 or 3,
preferably 1 or 3. Preferred catalysts are tris-
(triphenylphosphine)-rhodium(I)-chloride,
tris(triphenylphosphine)-rhodium(III)-chloride and tris-
(dimethylsulphoxide)-rhodium(III)-chloride, and tetrakis-
(triphenylphosphine) -rhodium hydride of formula ( (C6Hs) 3P) 4RhH,
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and the corresponding compounds in which triphenylphosphine
moieties are replaced by tricyclohexylphosphine moieties. The
catalyst can be used in small quantities. An amount in the
range of 0.01 to 1.0o preferably 0.03% to 0.5%, most preferably
0.06% to 0.120 especially about 0.08%, by weight based on the
weight of polymer is suitable.
The rhodium catalyst is preferably used with a co-
catalyst. Suitable co-catalysts include ligands of formula
RmB, where R, m and B are as defined above, and m is preferably
3. Preferably B is phosphorus, and the R groups can be the
same or different. Thus there can be used a triaryl, trialkyl,
tricycloalkyl, diaryl monoalkyl, dialkyl monoaryl diaryl
monocycloalkyl, dialkyl monocycloalkyl, dicycloalkyl monoaryl
or dicycloalkyl monoaryl co-catalysts. Examples of co-catalyst
ligands are given in US Patent No 4,631,315, the disclosure of
which is incorporated by reference. The preferred co-catalyst
ligand is triphenylphosphine. The co-catalyst ligand is
preferably used in an amount in the range 0.3 to 5%, more
preferably 0.5 to 4o by weight, based on the weight of the
terpolymer. Preferably also the weight ratio of the rhodium-
containing catalyst compound to co-catalyst is in the range 1:3
to 1:55, more preferably in the range 1:5 to 1:45.
A co-catalyst ligand is beneficial for the selective
hydrogenation reaction. There should be used no more than is
necessary to obtain this benefit, however, as the ligand will
be present in the hydrogenated product. For instance
triphenylphosphine is difficult to separate from the
hydrogenated product, and if it is present in any significant
quantity may create some difficulties in processing of the
product.
The hydrogenation reaction can be carried out in
solution. The solvent must be one that will dissolve the
styrene-butadiene-nitrile rubber. This limitation excludes use
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of unsubstituted aliphatic hydrocarbons. Suitable organic
solvents are aromatic compounds including halogenated aryl
compounds of 6 to 12 carbon atoms. The preferred halogen is
chlorine and the preferred solvent is a chlorobenzene,
especially monochlorobenzene. Other solvents that can be used
include toluene, halogenated aliphatic compounds, especially
chlorinated aliphatic compounds, ketones such as methyl ethyl
ketone and methyl isobutyl ketone, tetrahydrofuran and
dimethylformamide. The concentration of polymer in the solvent
is not particularly critical but is suitably in the range from
1 to 30% by weight, preferably from 2.5 to 20% by weight, more
preferably 10 to 15o by weight. The concentration of the
solution may depend upon the molecular weight of the styrene-
butadiene-nitrite rubber that is to be hydrogenated. Rubbers
of higher molecular weight are more difficult to dissolve, and
so are used at lower concentration.
The reaction can be carried out in a wide range of
pressures, from 10 to 250 atm and preferably from 50 to 100
atm. The temperature range can also be wide. Temperatures
from 60 to 160°, preferably 100 to 160°C, are suitable and from
110 to 140°C are preferred. Under these conditions, the
hydrogenation is usually completed in about 3 to 7 hours.
Preferably the reaction is carried out, with agitation, in an
autoclave.
Although the preferred catalyst for the selective
hydrogenation is a rhodium-containing Catalyst, it is possible
to use other catalysts. In general, many hydrogenation
catalysts are known to those skilled in the art, especially
catalysts of group VIIT metals and complexes containing these
metals. Mention is made of use of a ruthenium catalyst and a
ketone solvent, as taught in US Patent No 4,631,315, the
disclosure of which is incorporated herein by reference. Also
mentioned is Canadian Patent Application Serial No 2,020,012,
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the disclosure of which is incorporated by reference.
Palladium catalysts are also mentioned as candidates for use in
the selective hydrogenation.
Hydrogenation of ethylenic carbon-carbon double bonds
improves various properties of the polymer, particularly
resistance to oxidation. It is preferred to hydrogenate at
least 80% of the ethylenic carbon-carbon double bonds present.
For some purposes it is desired to eliminate all ethylenic
carbon-carbon double bonds, and hydrogenation is carried out
until all, or at least 99%, of the double bonds are eliminated.
For some other purposes, however, some residual ethylenic
carbon-carbon double bonds may be required and reaction may be
carried out only until, say, 90% or 95% of the bonds are
hydrogenated. The degree of hydrogenation is sometimes
expressed in terms of residual double bonds (RDB), being the
number of double bonds remaining after hydrogenation, expressed
as a percentage of those prior to hydrogenation. Usually, the
RDB is 10% or less and for some purposes it is less than 0.9%.
The degree of hydrogenation can be determined by
infrared spectroscopy or 1H-NMR analysis of the polymer. In
some circumstances the degree of hydrogenation can be
determined by measuring iodine value. This is not a
particularly accurate method, and it cannot be used in the
presence of triphenyl phosphine, so use of iodine value is not
preferred.
It can be determined by routine experiment what
conditions and what duration of reaction time result in a
particular degree of hydrogenation. It is possible to stop the
hydrogenation reaction at any preselected degree of
hydrogenation. The degree of hydrogenation can be determined
by ASTM D5670-95. (This test was designed for determining the
degree of hydrogenation of hydrogenated nitrite rubber (HNBR),
but Applicant's measurements using proton NMR measurements
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indicate that the test also works with (HSNBR)) See also Dieter
Brueck, Kautschuk + Gummi Kunststoffe, Vol 42, No 2/3 (1989),
the disclosure of which is incorporated herein by reference.
The process of the invention permits a degree of control that
is of great advantage as it permits the optimisation of the
properties of the hydrogenated polymer for a particular
utility. The degree of hydrogenation is also confirmed by
proton NMR analysis.
As stated, the hydrogenation of carbon-carbon
aliphatic double bonds is not accompanied by reduction of
nitrile groups or carbon-carbon aromatic double bonds. As
demonstrated in the examples below, 94% of the carbon-carbon
aliphatic double bonds of a styrene-butadiene-nitrile rubber
were reduced with no reduction of nitrile groups and carbon-
carbon aromatic double bonds detectable by infrared analysis.
The possibility exists, however, that reduction of nitrile
groups and aromatic double bonds may occur to an insignificant
extent, and the invention is considered to extend to encompass
any process or product such reduction has occurred to an
insignificant extent. By insignificant is meant that less than
0.5%, preferably less than O.lo, of the nitrite groups or
carbon-carbon aromatic double bonds originally present have
undergone reduction.
To extract the polymer from the hydrogenation
mixture, the mixture can be worked up by any suitable method.
One method is to distil off the solvent. Another method is to
inject steam, followed by drying the polymer. Another method
is to add alcohol, which causes the polymer to coagulate.
The catalyst can be recovered by means of a resin
column that absorbs rhodium, as described in US Patent No
4,985,540, the disclosure of which is incorporated herein by
reference.
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The hydrogenated styrene-butadiene-nitrite rubber-o°~
the invention can be crosslinked. Thus, it can be vulcanized
using sulphur or sulphur-containing vulcanizing agents, in
known manner. Sulphur vulcanization requires that there be
some unsaturated carbon-carbon double bonds in the polymer, to
serve as reactions sites for addition of sulphur atoms to serve
as crosslinks. If the polymer is to be sulphur-vulcanized,
therefore, the degree of hydrogenation is controlled to obtain
a product having a desired number of residual ethylenic double
bonds. For many purposes a degree of hydrogenation that
results in about 3 or 4% residual double bonds (RDB), based on
the number of double bonds initially present, is suitable. As
stated above, the process of the invention permits close
control of the degree of hydrogenation.
The hydrogenated styrene-butadiene-nitrite rubber can
be crosslinked with peroxide crosslinking agents, again in
known manner. Peroxide crosslinking does not require the
presence of double bonds in the polymer, and results in carbon-
containing crosslinks rather than sulphur-containing
crosslinks. As peroxide crosslinking agents there are
mentioned dicumyl peroxide, di-t-butyl peroxide, benzoyl
peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3 and 2,5-
dimethyl-2,5-di(benzoylperoxy)hexane and the like. They are
suitably used in amounts of about 0.2 to 20 parts by weight,
preferably 1 to 10 parts by weight, per 100 parts of rubber.
The hydrogenated styrene-butadiene-nitrite rubber of
the inventioi~.ed can be compounded with. any of the usual
compounding agents, for example fillers such as carbon black or
silica, heat stabilisers, antioxidants, activators such as zinc
oxide or zinc peroxide, curing agents, co-agents, processing
oils and extenders. Such compounds and co-agents are known to
persons skilled in the art.
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The hydrogenated styrene-butadiene-nitrile rubbers of
the invention display better heat ageing resistance and better
tensile strength than non-hydrogenated styrene-butadiene-
nitrile rubber. Surprisingly, they also display better
abrasion resistance, low temperature flexibility, and higher
modulus than non-hydrogenated styrene-butadiene-rubber. These
properties render them valuable for many specialised
applications, but particular mention is made of use as seals in
situations where severe stress is encountered, such as in high
stiffness automative belts, roll covers, and hoses.
Hydrogenated nitrile rubbers (HNBR) are used in many
specialised applications where difficult conditions are
encountered. Surprisingly, HSNBR has a higher modulus than
HNBR. Its abrasion resistance and other physical properties
are comparable with HNBR. Hydrogenated styrene-butadiene-
nitrile rubbers of this invention have physical properties that
are superior in some respects to those of commercially
available hydrogenated nitrile rubbers and hence are useful in
many applications where hydrogenated nitrile rubbers are of
proven utility. Mention is made of seals, especially in
automotive systems and heavy equipment and any other
environment in which there may be encountered high or low
temperatures, oil and grease. Examples include wheel bearing
seals, shack absorber seals, camshaft seals, power steering
assembly seals, O-rings, water pump seals, gearbox shaft seals,
and air conditioning system seals. Mention is made of oil well
specialties such as packers, drill-pipe protectors and rubber
stators in down-hole applications. Various belts and mountings
are provided in demanding environments and the properties of
hydrogenated styrene-butadiene-nitrite rubber of this invention
render it suitable for applications in camshaft drive belts,
oil-cooler hoses, poly-V belts, torsional vibration dampeners,
boots and bellows, chain tensioning devices, and overflow caps.
The high modulus and high abrasion resistance of HSNBR renders
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it useful for high-hardness roll applications in, for instance,
metal-working rolls, paper industry rolls, printing rolls,
elastomer components for looms and textile rolls.
The hydrogenated styrene-butadiene-nitrite rubber can
be used in the form of a latex. Formation of a latex can be
carried out by milling the hydrogenated rubber in the presence
of water containing appropriate emulsifiers until the required
latex is formed. Suitable emulsifiers for this purpose include
anionic emulsifiers such as fatty acid soaps, i.e., sodium and
potassium salts of fatty acids, rosin acid salts, alkyl and
aryl sulfonic acid salts and the like. Oleate salts are
mentioned by way of example. The rubber latex may be in
solution in an organic solvent, or in admixture with an organic
solvent, when added to the water, to form an oil-in-water
emulsion. The organic solvent is then removed from the
emulsion to yield the required latex. Organic solvents that
can be used include the solvents that can be used for the
hydrogenation reaction.
The invention is further illustrated in the following
examples and in the accompanying drawings. In the examples,
tests to determine properties were carried out in accordance
with ASTM or DIN procedures. Of the drawings:
Figure 1 is a graph showing the infrared spectrum of
the polymer prior to and subsequent to hydrogenation;
Figure 2 is a graph of tan $ and temperature for a
hydrogenated styrene-butadiene-nitrite rubber of the invention.
Figure 3 is a graph of tan 8 and temperature of an
unhydrogenated styrene-butadiene-nitrite rubber, for purpose of
comparison.
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Figure 4 is a graph of stress versus strain, showing
that HSNBR has a higher modulus than two Compounds of HNBR and
one of SNBR; and
Figure 5 is a graph showing results of a Pico
abrasion test carried out on HSNBR of the invention and SNBR,
for comparison.
Selective Hydrogenation of SNBR
EXAMPLE 1
In a lab experiment with a 12o polymer load, 392 g of
a statistical styrene-acrylonitrile-butadiene terpolymer
containing 20o by weight of acrylonitrile, 20% styrene, balance
butadiene, ML 1+4/125°C=25 (Krylene VPKA8802, commercially
available from Bayer), in 2.9 kg of chlorobenzene was
introduced into a 2 US gallon Parr high-pressure reactor. The
reactor was degassed 3 times with pure H2(100-200 psi) under
full agitation (600 rpm). The temperature of the reactor was
raised to 130°C and a solution of 0.3928 (0.1 phr) of tris-
(triphenylphosphine)-rhodium-(I) Chloride catalyst and 4.588 of
co-catalyst triphenylphosphine (TPP) in 60 ml of
monochlorobenzene having an oxygen content less than 5 ppm was
then charged to the reactor under hydrogen. The temperature
was raised to 138°C and the pressure of the reactor was get at
1200 psi (83 atm). The reaction temperature and hydrogen
pressures of the reactor were maintained constant throughout
the whole reaction. The degree of hydrogenation was monitored
by sampling after a certain reaction time followed by Fourier
Transfer Infra Red Spectroscopy (FTIR) analysis of the sample.
Reaction was carried out for 180 min at 138°C under a hydrogen.
pressure of 83 atmospheres. Thereafter the chlorobenzene was
removed by the injection of steam and the polymer was dried in
an oven at 8 0 °C .
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Samples were taken and tested for degree of
hydrogenation of ethylenic double bonds. Results are given in
Table 1.
Table 1
Time(min) Degree of Residual Double
hydrogenation % Bonds (RDB)
0 0 100
60 95.3 4.7
75 98.5 1.5
180 99.2 0.8
The FTIR result (Figure 1) showed that the nitrite
groups and the aromatic double bonds of the polymer remained
intact after the hydrogenation, indicating that the
hydrogenation is selective towards the ethylenic C=C bonds
only. The peak for ethylenic carbon-carbon double bonds has
disappeared after hydrogenation. The peaks for the nitrite
groups and for the styrene remain, indicating that there has
been no detectable reduction of nitrite and aromatic double
bonds.
The low temperature flexibility of the product of
Example 1 and of Krylene VPKA 8802 was determined by using a
Rheometrics Solid analyser (RSA-II). In this test, a small
sinusoidal tensile deformation is imposed on the specimen at a
given frequency. The resulting force, as well as the phase
difference between the imposed deformation and the response,
are measured at various temperatures. Based on theory of
linear viscoelasticity, the storage tensile modulus (E'), loss
tensile modulus (E") and tan & can be calculated. In general,
as the temperature decreases, rubber becomes more rigid, and
the E' will increase. At close to the glass transition
temperature, there will be a rapid increase in E'. Figures 2
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and 3 are graphs of the elastic modulus E' and the viscous
modulus E" and temperature for the HSNBR product of Example 1
and for the unhydrogenated SNBR, Krylene VPKA 8802,
respectively. The figures also show tan 8, which equals
tan . It is desirable that the peak value of tan ~ shall be
as low as possible, and also that the peak value of tan 8 shall
occur at as low a temperature as possible. It is observed that
the HSNBR is superior to the SNBR in both of these respects.
EXAMPLE 2
In a experiment similar to Example 1, 184 g of a
statistical styrene-butadiene-acrylonitrile terpolymer
containing 10% by weight of acrylonitrile, 20% by weight of
styrene, balance butadiene (Krylene VPKA 8683, commercially
avaiable from Bayer) in 2.9 Kg chlorobenzene was introduced
into a 2 US gallon Parr high-pressure reactor. The reactor was
degassed 3 times with pure H~ (100-200psi) under full agitation
(600 rpm). The temperature of the reactor was raised to 138°C
and a solution of 0.376 g (0.205 phr) of tris-
(triphenylphosphine)-rhodium-(I) chloride catalyst and 6.262 g
(3.42phr) of co-catalyst triphenylphosphine (TPP) in 60 ml of
monochlorobenzene having an oxygen content less than 5ppm was
the charged to the reactor under hydrogen. The temperature was
raised to 138°C and the pressure of the reactor was set at
1200psi (83 atm). The degree of hydrogenation was monitored,
the reaction carried out, and the product recovered, as
described in Example 1.
Samples were taken and tested for degree of
hydrogenation of ethylenic double bonds. Results are given in
Table 2.
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Table 2
Time (min) Degree of hydrogenation o Residual Double
Bonds (RDB) o
0 0 100
60 62.4 17.6
120 93.9 6.1
150 95.7 4.3
Example 3
The hydrogenated styrene-butadiene-nitrile rubber of
Example 1 was crosslinked and subjected to various tests. For
purposes of comparison, the unhydrogenated styrene-butadiene-
nitrile rubber (Krylene VPKA 8802) was also crosslinked and
tested. Compound formulations are given in Table 3, compound
Mooney Viscosities are given in Table 4, MDR cure
characteristics are given in Table 5, stress-strain data after
oven-aging are given in Table 6 and low temperature stiffness
data are given in Table 7.
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Table 3
Compound Formulations
HSNBR (6% RDB) Krylene VPKA 8802
CARBON BLACK, N 330 40 40
HSNBR ( 2 0 % ACN, 6 % 10 0
RDB )
KRYLENE VPKA 8802 (SNBR) 100
NAUGARD 445 1 1
PLASTHALL TOTM 3 3
STEARIC ACID 1 1
VULKANOX ZMB-2/C5 0.4 0.4
(ZMMBI)
ZINC OXIDE (KADOX 920) 3 3
SPIDER SULFUR 0.5 0.5
VULKACIT CZ/EG-C (CBS) 0.5 0.5
VULKACIT THIUR.AM/C (D) 2 2
NAUGARD 445 (Uniroyal) and Vulkanox ZMB-2/C5 (Bayer)
are Commercially available antioxidants. Plasthall TOTM
(C.P.Hall) is an ester-based oil plasticiser. Vulkacit CZ/EG-C
(CBS) (BAYER) is a sulfenamide curing agent and Vulkacit
Thiuram/C (D) (Bayer) is a thiuram curing agent.
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Table 4
Compound Mooney Viscosity
HSNBR (6% RDB) Krylene VPKA 802
Rotor Size large large
Test Temperature (C) 125 125
Preheat Time (min) 1 1
Run Time (min) 4 4
Mooney Viscosity (MU) 65.8 32.5
Test Temperature (C) 135 135
Mooney Viscosity (MU) 55.2 28
Table 5
MDR CURE CHARACTERISTICS
HSNBR (6% RDB) Krylene VPKA 8802
Frequency (Hz) 1.7 1.7
Test Temperature (C) 170 170
Degree Arc () 1 1
Test Duration (min) 30 30
Torque Range ( dN . m) 10 0 10 0
Chart No. 142 143
MH (dN.m) 36.93 32.92
ML (dN.m) 3.35 1.82
Delta MH-ML (dN.m) 33.56 31.1
is 1 (min) 1.14 0.87
is 2 (min) 1.38 0.99
t' 10 (min) 1.54 1.04
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Table 5 Continued
t' 25 (min) 1.89 1.2
t' 50 (min) 2.23 1.4
t' 90 (min) 3.76 2.24
t' 95 (min) 4.85 2.8
Delta t'50 - t'10 (min) 0.69 0.36
Table 6
Stress-Strain Data After Aging
HSNBR (6o RDB) Krylene VPKA 8802
Cure Time (min) 20 20
Cure Temperature (C) 170 170
Test Temperature (C) 23 23
Ageing Time (hrs) 504 504
Ageing Temperature (C) 135 135
Ageing Type air oven air oven
Hardness Shore A2 (pts.) 86 94
Ultimate Tensile (MPa) 22.07 1.65
Ultimate Elongation (%) 127 0
Stress @ 100 (MPa) 19.2
Stress ~ 200 (MPa)
Stress C~ 25 (MPa) 4.83
Stress C 300 (MPa)
Stress C~ 50 (MPa) 9.24
Chg. Hrd. Shore A2 13 27
(pts . )
Chg. Ulti. Tens. (%) -36 -94
Chg. Ulti. Elong. (o) -70
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Table 6 Continued
Change Stress @ 100 (o) 401
Change Stress @ 200 (%)
Change Stress C 25 (%) 218
Change Stress C 300 (%)
Change Stress C 50 (%) 330
The HSNBR showed much better aging resistance than
SNBR. Note, for instance, that the ultimate tensile strength
of HSNBR is markedly superior to that of SNBR, and the ultimate
elongation of SNBR is close to zero and could not even be
measured, nor could its stress at 25MPa, whereas stress for
HSNBR was measurable up to 100MPa.
Table 7
Gehman Low Temp Stiffness
HSNBR (6o RDB) Krylene VPKA
8802
Cure Time (min) 20 20
Cure Temperature (C) 170 170
Start Temperature (min) -50 -50
Temperature ~ T2 (C) -5 -1
Temperature C T5 (C) -12 -7
Temperature C T10 (C) -14 -10
Temperature C T100 (C) -24 -17
In this Gehman stiffness test, lower numbers indicate
better results, so it is clear that HSNBR shows better cold
flexibility than SNBR.
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Example 4
The polymer compounds used in Example 3 were
crosslinked and subjected to tests as set forth below. For
comparison compounds of unhydrogenated SNBR (Krylene 8802) and
two commercially available hydrogenated nitrile rubbers
(Therban C3467 and Therban VPKA 8830, from Bayer) were also
tested. Compound formulations are given in Table 8. Tables 9
and 10 give the results obtained by subjecting the compounds to
Die B and Die C tear strength tests. These tests are not
particularly discriminating, but show that the two HNBR's,
HSNBR and SNBR are approximately similar in tear strength. The
results of measuring stress v strain are given in Table 11 and
graphically in Figure 4. Surprisingly, HSNBR is superior to
both HNBR's and to SNBR.
Results of stress-strain tests after hot air oven
ageing at 135° for 168 hours, 336 hours and 504 hours are given
in Table 12, and demonstrate that HSNBR ages better than SNBR.
Results of stress-strain tests after aging in oil and in water
are in Tables 13 and 14 and, again, demonstrate the superiority
of HSNBR, showing that it has good oil-resistance and good
water-resistance.
Results of DIN abrasion tests and PICO abrasion tests
are given in Table 15 and 16 respectively. Again, the
superiority of HSNBR is demonstrated. The PICO test results
are shown graphically in Figure 5.
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Table 8
Compound Formulations
HNBR ( HNBR ( 2 HSNBR SNBR
1 ) )
CARBON BLACK, N 330 VULCAN 40 40 40 40
3
HSNBR (VIA 8802) 94% 100
KRYLENE VPKA 8802 100
THERBAN C 3467 100
THERBAN VP KA 8830 100
NAUGARD 445 1 1 1 1
PLASTHALL TOTM 3 3 3 3
STEARIC ACID EMERSOL 132 NF 1 1 1 1
VULKANOX ZMB-2/C5 (ZMMBI) 0.4 0.4 0.4 0.4
ZINC OXIDE (KADOX 920) 3 3 3 3
GRADE PC
SPIDER SULFUR 0.5 0.5 0.5 0.5
VULKACIT CZ/EG-C (CBS) 0.5 0.5 0.5 0.5
VULKACIT THIURAM/C (D) 2 2 2 2
Specific Gravity 1.118 1.109 1.118 1.118
Table 9
Die B Tear
HNBR (1) HNBR (2) HSNBR SNBR
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Crosshead Speed (mm/min) 500 500 500 500
Test Temperature (C) 23 23 23 23
Tear Strength (kN/m) 75.15 75.89 67.52 49.44
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Table 9 Continued
RUN 2
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Crosshead Speed (mm/min) 500 500 500 500
Test Temperature (C) 100 100 100 100
Tear Strength (kN/m) 19.16 18.41 19.42 20.66
RUN 3
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Crosshead Speed (mm/min) 500 500 500 500
Test Temperature (C) 150 150 150 150
Tear Strength (kN/m) 11.6 12.9 11.52 12.35
RUN 4
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Crosshead Speed (mm/min) 500 500 500 500
Test Temperature (C) 170 170 170 170
Tear Strength (kN/m) 9.43 9.71 9.34 10.75
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Table 10
Die C Tear
HNBR (1) HNBR HSNBR SNBR
(2)
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Test Temperature (C) 23 23 23 23
Tear Strength (kN/m) 53.61 53.01 46.02 40.29
RUN 2
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Test Temperature (C) 100 100 100 100
Tear Strength (kN/m) 23.91 19.62 20.54 19.48
RUN 3
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Test Temperature (C) 150 150 150 150
Tear Strength (kN/m) 11.03 12.64 8.95 9.89
RUN 4
Cure Time (min) 2 0 2 0 2 0 2 0
Cure Temperature (C) 170 170 170 170
Test Temperature (C) 170 170 170 170
Tear Strength (kN/m) 8.79 9.54 7.62 9.14
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Table 11
STRESS-STRAIN
HNBR (1) HNBR (2) HSNBR SNBR
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Dumbell die C die C die C die C
Test Temperature (C) 23 23 23 23
Hard. Shore A2 Inst. 69 69 73 67
(pts . )
Ultimate Tensile (MPa) 37.41 37.5 34.37 29.51
Ultimate Elongation (%) 484 451 425 469
Stress C 100 (MPa) 2.75 2.8 3.83 2.75
Stress C~ 200 (MPa) 8.16 8.45 10.86 7.56
Stress C 25 (MPa) 1.25 1.31 1.52 1.18
Stress C 300 (MPa) 16.69 17.87 20.17 15.08
Stress ~ 50 (MPa) 1.7 1.76 2.15 1.67
Table 12
STRESS-STRAIN AFTER AGING IN HOT OVEN
HNBR (1) HNBR (2) HSNBR SNBR
Cure Time (min) 20 20 20 20
Cure Temperature () 170 170 170 170
Test Temperature (C) 23 23 23 23
Ageing Time (hrs) 168 168 168 168
Ageing Temperature (C) 135 135 135 135
Ageing Type air oven air oven air oven air oven
Hardness Shore A2 (pts.) 76 75 83 79
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Table 12 Continued
Ultimate Tensile (MPa) 31.1 32.79 25.05 16.76
Ultimate Elongation (%) 316 352 235 107
Stress @ 100 (MPa) 6.49 6 10.81 15.44
Stress C 200 (MPa) 18.19 16.93 22.55
Stress C 25 (MPa) 1.86 1.85 2.77 3.84
Stress @ 300 (MPa) 29.48 28.15
Stress C 50 (MPa) 2.92 2.83 4.89 7.07
Chg. Hard. Shore A2 7 6 10 12
(pts . )
Chg. Ulti. Tens. (o) -17 -13 -27 -43
Chg. Ulti. Elong. (%) -35 -22 -45 -77
Change Stress C 100 (%) 136 114 182 461
Change Stress C 200 (%) 123 100 108
Change Stress C 25 (%) 49 41 82 225
Change Stress C 300 (%) 77 58
Change Stress C~ 50 (%) 72 61 127 323
RUN 2
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Test Temperature (C) 23 23 23 23
Ageing Time (hrs) 336 336 336 336
Ageing Temperature (C) 135 135 135 135
Ageing Type air oven air oven air oven air oven
Hardness Shore A2 (pts.) 80 77 85 84
Ultimate Tensile (MPa) 26.5 29.55 22.19 16.7
Ultimate Elongation (%) 208 255 152 <01
Stress C 100 (MPa) 10.32 9.35 ~ 14.99
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Table 12 Continued
Stress ~ 200 (MPa) 25.26 23.33
Stress @ 25 (MPa) 2.54 2.38 3.94 11.91
Stress @ 300 (MPa)
Stress C 50 (MPa) 4.48 4.01 7.11
Chg. Hard. Shore A2 11 8 12 17
(pts . )
Chg. Ulti. Tens. (%) -29 -21 -35 -43
Chg. Ulti. Elong. (%) -57 -43 -64
Change Stress @ 100 (%) 275 234 291
Change Stress @ 200 (%) 210 176
Change Stress ~ 25 (%) 103 82 159 909
Change Stress C 300 (%)
Change Stress @ 50 (%) 164 128 231
RUN 3
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Test Temperature (C) 23 23 23 23
Ageing Time (hrs) 504 504 504 504
Ageing Temperature (C). 135 135 135 135
Ageing Type air oven air oven air oven air oven
Hardness Shore A2 (pts.) 80 81 86 94
Ultimate Tensile (MPa) 25.42 26.51 22.07 1.65
Ultimate Elongation (%) 165 201 127 0
Stress ~ 100 (MPa) 13.17 11.43 19.2
Stress C~ 200 (MPa) 25.48
Stress @ 25 (MPa) 2.93 2.8 4.83
Stress C 300 (MPa)
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Table 12 Continued
Stress C 50 (MPa) 5.35 4.088 9.24
Chg. Hard. Shore A2 11 12 13 27
(pts . )
Chg. Ulti. Tens. (o) -32 -29 -36 -94
Chg. Ulti. Elong. (o) -66 -55 -70
Change Stress C 100 (o) 379 308 401
Change Stress ~ 200 (%) 202
Change Stress C 25 (o) 134 114 218
Change Stress @ 300 (%)
Change Stress ~ 50 (%) 215 132 330
Table 13
STRESS-STRAIN AFTER AGING IN OIL
HNBR (1) HNBR (2) HSNBR SNBR
Cure Time (min) 20 20 20 20
Cure Temperature 170 170 170 170
(C)
Ageing Time 120 120 120 120
(hrs)
Ageing 150 150 150 150
Temperature (C)
Ageing Type Block Block Block Block
Ageing Medium ASTM Oil ASTM Oil ASTM Oil ASTM Oil
1 1 1 1
Test Temperature 23 23 23 23
(C)
26
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Table 13 Continued
Hardness Shore 66 65 66 66
A2 (pts . )
Ultimate Tensile 32.51 35.09 37.35 13
(MPa)
Ultimate 463 492 485 233
Elongation (%)
Stress C~ 25 1.27 1.22 1.2 1.23
(MPa)
Stress ~ 50 1.71 1.64 1.76 1.8
(MPa)
Stress C 100 2.76 2.58 3.08 3.29
(MPa)
Stress C~ 200 8.49 8.56 9.61 9.87
(MPa)
Stress C 300 17.34 18.62 19.01
(MPa)
Chg. Hard. Shore -3 -4 -7 -1
A2 (pts.)
Chg. Ulti. Tens. -13 -6 9 -56
( a)
Chg. Ulti. -4 9 14 -50
Elong. (%)
Change Stress @ 2 -7 -21 4
25 (%)
Change Stress @ 1 -7 -18 8
50 (%)
Change Stress C 0 -8 -20 20
100 (%)
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Table 13 Continued
Change Stress C 4 1 -12 31
200 (%)
Change Stress ~ 4 4 -6
300 (%)
Wt. Change (%) -0.5 -1.2 2.4 -3.6
Vol. Change (%) 0.7 -0.1 5.4 -2.5
Table 14
STRESS-STRAIN AFTER AGING IN WATER
HNBR ( HNBR~ ( HSNBR SNBR
1 ) 2 )
Cure Time (min) 20 20 20 20
Cure Temperature () 170 170 170 170
Ageing Time (hrs) 168 168 168 168
Ageing Temperature (C) 70 70 70 70
Ageing Type Block Block Block Block
Ageing Medium Water Water Water Water
Test Temperature (C) 23 23 23 23
Hardness Shore A2 (pts.) 71 67 71 65
Ultimate Tensile (MPa) 34.8 36.09 34.56 26.29
Ultimate Elongation (%) 434 413 408 415
Stress ~ 25 (MPa) 1.28 1.33 1.51 1.23
Stress C~ 50 (MPa) 1.82 1.85 2.19 1.81
Stress @ 100 (MPa) 3.2 3.19 4.07 3.38
Stress @ 200 (MPa) 9.95 10.17 11.88 9.71
Stress C 300 (MPa) 19.49 20.94 22.02 17.47
Chg. Hard. Shore A2 2 -2 -2 -2
(pts . )
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Table 14 Continued
Chg. Ulti. Tens. (%) -7 -4 1 -11
Chg. Ulti. Elong. (o) -10 -8 -4 -12
Change Stress @ 25 (o) 2 2 -1 4
Change Stress C 50 (%) 7 5 2 8
Change Stress ~ 100 (o) 16 14 6 23
Change Stress C 200 (%) 22 20 9 28
Change Stress ~ 300 (%) 17 17 9 16
Wt. Change (o) 0.5 0.6 1.3 4
Vol. Change (%) 0.3 0.3 2.2 4.7
Table 15
DIN ABRASION
HNBR (1) HNBR (2) HSNBR SNBR
Cure Time (min) 170 170 170 170
Cure Temperature (C) 25 25 25 25
Specific Gravity 1.11 1.115 1.125 1.145
Abrasion Volume Loss (mm3) 70 64 99 119
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Table 16
PICO ABRASION
HNBR ( HNBR ( HSNBR SNBR
1 ) 2 )
Cure Time (min) 20 20 20 20
Cure Temperature (C) 170 170 170 170
Revolution 80 80 80 80
Specific Gravity
Severity STD STD STD STD
Abrasion Volume Loss (Cm3) 0.0038 0.003 0.0029 0.0079
Abrasive Index 526.71 702.81 730.93 28.64
SUBSTITUTE SHEET (RULE 26)
