Note: Descriptions are shown in the official language in which they were submitted.
2~48929
HYDROGENATED_ BUTADIENE/ISOPRENE/(METH)ACRYLONITRILE CO-
POLYMERS
This invention relates to selectively hydrogenated
butadiene/isoprene/(meth)acrylonitrile copolymers, to a
process for their production by catalytic hydrogenation of
the butadiene/isoprene/(meth)acrylonitrile copolymers with
hydrogen and to the use of the hydrogenated copolymers for
the production of vulcanizates. In the context of the
invention, "selective hydrogenation" is understood to be
the hydrogenation of the olefinic C=C double bonds with the
C-N triple bonds remainlng intact. In the present context,
"with the C--N triple bonds remaining intact" means that
less than 7, preferably less than 5, more preferably less
than 3 and, most preferably, less than 1.5% of the nitrile
groups originally present in the polymeric starting product
are hydrogenated.
It is known that hydrogenated nitrile rubber ("HNBR")
obtained by selective hydrogenation of nitrile rubber
(butadiene/acrylonitrile copolymer, hereinafter referred to
as "NBR") is distinguished by high tensile strength,
minimal abrasion, high oil resistance and remar~able
stability to oxidative influences. However, the compres-
sion set at low temperature is not entirely satisfactory.
It has now surprisingly been found that isoprene-
modified NBR gives a hydrogenation product which combines
the desirable properties of HNBR with improved compression
set at low temperature (for the same degree of hydrogena-
tion). The compression set values which it is now possible
to achieve at low temperature could hitherto only be
achieved by HNBR having a relatively high C=C double bond
content, i.e. with losses of stability, for example to
oxidative influences and to aggressive media, such as for
example hydrogen sulfide and amines.
Accordingly, the present invention relates to a
Le A 27 581-US/JP/CA
20~892~1
process for the selective hydrogenation of butadiene/
isoprene/acrylonitrile copolymers containing 3.5 to 22% by
weight copolymerized isoprene and 18 to 50~ by weight
copolymerized acrylonitrile, the acrylonitrile being
completely or partly replaceable by an equimolar quantity
of methacrylonitrile, with hydrogen in an organic solvent
under a hydrogen pressure of 1 to 350 bar, preferably 5 to
250 bar and, more preferably, 10 to 200 bar and at tem-
peratures of 20 to 250C, preferably 80 to 200'C, more
preferably 100 to 180C and, most preferably, 120 to 160=C
in the presence of 2 to 3,000, preferably 3 to 1,000, more
preferably 4 to 400 and, most preferably, 5 to 300 ppm
metal or metal compound as hydrogenation catalyst (ex-
pressed as metal and based on copolymer) to a degree of
hydrogenation of at least 85%, based on C=C double bonds
of the copolymer.
The present invention also relates to selectively
hydrogenated butadiene/isoprene/acrylonitrile copolymers
having degrees of hydrogenation, based on the C=C double
bonds of the copolymer, of at least 85% which have been
obtained by hydrogenation of copolymers containing 3.5 to
22% by weight copolymerized i,oprene and 18 to 50% by
weight copolymerized acrylonitrile, the acrylonitrile being
completely or partly replaceable by an equimolar quantity
of methacrylonitrile.
Finally, the present invention relates to the use of
the hydrogenated copolymers for the production of vul-
canizates.
The hydrogenated copolymers according to the invention
have particularly good properties when the correlation de-
scribed below between the copolymerized isoprene and co-
polymerized acrylonitrile contents in the starting material
(before hydrogenation) is fulfilled:
Le A 27 581 2
20~8~29
Content of copolymerized
Acrylonitrile Isoprene (% by weight)
(% by weight)
18 - 23 max. 22, preferably 9 - 18, more
preferably 10 - 17
23 - 29 max. 17, preferably 6 - 15, more
preferably 8 - 14
29 - 35 max. 15, preferably 3.5 - 13, more
preferably 6 - 12
25 - 41 max. 12, preferably 3.5 - 11, more
preferably 5 - 9
41 - 48 max. 18, preferably 3.5 - 16, more
preferably 5 - 15
An optimal combination of properties of the hydrogena-
ted copolymers in regard to compression set at low tem-
perature and resistance to oxidative attack and to aggres-
sive medla is obtained in the hydrogenation of copolymers
of which the copolymerized isoprene and acrylonitrile
contents are limited by the curves A (upper limit) and B
(lower limit) in Fig. 1. (Equimolar ratios apply to
methacrylonitrile.)
Processes for the hydrogenation of NBR are known and
may also be used for the production of the hydrogenation
products according to the invention. Rhodium or ruthenium
is generally used as the catalyst, although platinum,
iridium, palladium, rhenium, cobalt or copper in the form
of the metals, but preferably in the form of metal
compounds, may also be used, cf. for example US-PS 3,700,
637, DE-PS 2,539,132, EP-PS 134 023, DE-OS 35 41 689, 35 40
918, EP-A 298 386, DE-OS 35 29 252, DE-OS 34 33 392, US-PS
4,464,515 and 4,503,196.
Suitable catalysts and solvents for hydrogenation in
homogeneous phase are described in the following.
Preferred rhodium compounds as catalysts correspond to
the following formulae
Le A 27 581 3
20~8929
Rh Hal P[~
or /
~ ~ 3~ (Il)
in which
Hal is a halogen from the group consisting of chlorine,
bromine and iodine and
R is hydrogen, C14 alkyl (for example methyl, isopropyl),
Cl4 alkoxy (for example methoxy) or halogen from the
group consisting of chlorine, bromine and iodine.
Preferred ruthenium compounds correspond to the
following formula
RuX2y[(Ll)n (L2)sZ] (III)
in which
X is hydrogen, halogen, SnCl3,
L1 is hydrogen, halogen, (Rs-COO)n and cyclopentadienyl
corresponding to the following formula
R5 Rl
~ IV)
R4~R2
R3
Le A 27 581 4
2 ~ 2 9
in which Rl to Rs independently of one another repre-
sent hydrogen, methyl, ethyl or phenyl; adjacent sub-
stituents together may also form a hydrocarbon radical
such that L1 is an indenyl or fluorenyl system,
L2 is a phosphane, bisphosphane or arsane,
y is 0, 0.5 or 1,
n is 1 or 2,
z is an integer of 1 to 4,
R6 is an alkyl, cycloalkyl, aryl or aralkyl containing 1
to 20 carbon atoms.
Examples of Ll ligands of the cyclopentadienyl type
include cyclopentadienyl, pentamethyl cyclopentadienyl,
ethyl tetramethyl cyclopentadienyl, pentaphenyl cyclopen-
tadienyl, dimethyl triphenyl cyclopentadienyl, indenyl and
fluorenyl. The benzene rings in the Ll ligands of the
indenyl and fluorenyl type may be substituted by C16 alkyl
radicals, more particularly methyl, ethyl and isopropyl;
Cl4 alkoxy radicals, more particularly methoxy and ethoxy;
aryl radicals, more particularly phenyl; and halogens, more
particularly fluorine and chlorine. Preferred Ll ligands of
the cyclopentadienyl type are lhe unsubstituted radicals
cyclopentadienyl, indenyl and fluorenyl.
In the ligand L1 of the (R6 COO)n type, R6 may be
selected, for example, from linear or branched, saturated
hydrocarbon radicals containing 1 to 20, preferably 1 to 12
and, more preferably, 1 to 6 carbon atoms, cyclic saturated
hydrocarbon radicals containing 5 to 12 and preferably 5 to
7 carbon atoms, aromatic hydrocarbon radicals from the
benzene series containing 6 to 18 and preferably 6 to 10
carbon atoms, aryl-substituted alkyl radicals which, in the
aliphatic part, consist of a linear or branched C16 hydro-
carbon radical and, in the aromatic part, of a radical of
the benzene series, preferably phenyl.
The substituents R6 defined above may optionally be
substituted by hydroxy, Cl6 alkoxy, Cl6 carbalkoxy, fluor-
Le A 27 581 5
2~4~929
ine, chlorine or di-C14-alkylamino, in addition to which the
cycloalkyl, aryl and aralkyl radicals may be substituted by
C~-6 alkyl. Alkyl, cycloalkyl and aralkyl groups may contain
keto groups.
Examples of the substituent R6 are methyl, ethyl,
propyl, isopropyl, tert.-butyl, cyclohexyl, phenyl, benzyl
and trifluoromethyl. Preferred substituents R~ are methyl,
ethyl and tert.-butyl.
Preferred L2 ligands are phosphanes and arsanes
corresponding to the following formulae
R7 - P - R9 and R7 - As - R9
l3 18
(V) (VI)
ln which R7, R8 and R9 independently of one another have the
same meaning as R6.
Preferred L2 ligands corresponding to formulae (V) and
(VI) are triphenyl phosphane, diethyl phenyl phosphane,
tritolyl phosphane, trinaphthyl phosphane, diphenyl methyl
phosphane, diphenyl butyl phosphane, tris-(p-carbmethox-
yphenyl)-phosphane, tris-(p-cyanophenyl)-phosphane, tri-
butyl phosphane, tris-(trimethoxyphenyl)-phosphanes, bis-
(trimethylphenyl)-phenyl phosphanes, bis-(trimethoxy-
phenyl)-phenyl phosphanes, trimethylphenyl diphenyl phos-
phanes, trimethoxyphenyl diphenyl phosphanes, tris-(di-
methylphenyl)-phenyl phosphanes, tris-(dimethoxyphenyl)-
phosphanes, bis-(dimethylphenyl)-phenylphosphanes, bis-
(dimethoxyphenyl)-phenyl phosphanes, dimethylphenyl diphen-
yl phosphanes, dimethoxyphenyl diphenyl phosphanes, tri-
phenyl arsane, ditolyl phenyl arsane, tris-(4-ethoxypheny-
l)-arsane, diphenyl cyclohexyl arsane, dibutyl phenyl
arsane and diethyl phenyl arsane. Triaryl phosphanes, more
especially triphenyl phosphane, are particularly preferred.
Le A 27 581 6
20~892~ -
Other examples of L2 ligands are bisphosphanes corre-
sponding to the following formula
Rl R12
P - (CH2)1 - P (VII)
Rll/ \Rl3
in which 1 is an integer of 1 to 10 and the substituents,
R1~, R11, R12 and R13 independently of one another have the
same meaning as R6.
Examples of bisphosphanes are 1,2-bis-diphenylphos-
phanoethane, 1,2-bis-dianisylphosphanoethane, 1,3-bis-
diphenylphosphanopropane, and 1,4-bis-diphenylphosphano-
butane. 1,2 -Bis-diphenylphosphanoethane is preferred, 1,3-
bis-diphenylphosphanopropaneandl,4-bis-diphenylphosphano-
butane being particularly preferred.
The definition of the compounds (III) is also intended
to encompass compounds in which L1 and L2 are attached to
one another by one or more covalent bonds. Examples of
such compounds are compounds corresponding to the following
formula
Rl5
RuX2y Cp-(C~2)q-P-(cH2~r-p (VIII)
Rl4 \Rl6
Cp: cyclopentadienyl
in which q and r independently of one another represent an
integer of 1 to 6 and the substituents R14 to R16
independently of one another may have the same meaning as
R6 .
Examples of ligands in square brackets in formula
(VIII)arel,4-diphospha-6-cyclopentadienyl-1,1,4-triphenyl
hexane, preferably 1,5-diphospha-7-cyclopentadienyl-1,1,5-
Le A 27 581 7
2~929
triphenyl heptane and, in particular, 1,6-diphospha-8-
cyclopentadienvl~ triphenyl octane.
The following are particularly preferred ruthenium
complex catalysts corresponding to formula (III):
RuC12 (PPh3)3
RuHCl (PPh3)3
RuH2 (PPh3)4
RuH4 (PPh3)3
RuH (CH3C00) (PPh3)3
RuH (C2H5COO) (PPh3)3
RuH [(CH3)3C CO0] (PPh3)3
Ru (CH3 COO) 2 ( PPh3) 2
RuCl (Cp) (PPh3) 2
RuH (Cp) (PPh3) 2
Ru (SnCl3) (Cp) (PPh3) 2
RuCl (~5-CgH7) (PPh3) 2
RllH (~5-CgH7) (PPh3) 2
Ru (SnCl3) (~5-CgH7) (PPh3)2
RuCl (~5-C~3Hg) (PPh3) 2
RuH (~5-C~3Hg) (PPh3) 2
Ru (SnCl3) (~ -C13Hg) (PPh3) 2
RuCl (~5-C9~7) (dppe)
in which "Ph" is phenyl, "Cp" is cyclopentadienyl and
"dppe" is 1,2-bis-diphenylphosphanoethane.
Catalysts soluble in the organic solvent used for
hydrogenation are preferably used. In the context of the
invention, catalysts are "soluble" if more than 50% by
weight, preferably more than 65% by weight and, more
preferably, more than 80% by weight of a quantity of 3.4 g
of catalyst dissolve in 2 liters of the particular solvent
at 20~C.
Preferred organic solvents, particularly where rhodium
compounds are used, include chlorinated aromatic hydro-
Le A 27 581 8
2~8929
carbons, such as for example chlorobenzene and dichloroben-
zenes. Preferred organic solvents, particularly where
ruthenium compounds are used, include C3 ~ ketones and, in
particular, mixtures of
a) C3-6 ketone and
b) monohydric, secondary or tertiary C3 ~ alcohol, the
content of b) in the mixture being from 2 to 60% by
weight, preferably from 5 to 50% by weight and, more
preferably, from 7 to 40% by weight.
Preferred C3-6 ketones are, for example, acetone,
butanone, pentanones, cyclopentanone and cyclohexanone and
mixtures thereof. Butanone and, in particular, acetone are
preferrecl.
Preferred C3-6 alcohols are, for example, 2-propanol,
2-butanol, 2-methyl-2-propanol, 2- and 3-pentanol, 3-
methyl-2-butanol, 2-methyl-2-butanol, 2-, 3- and 4-hexanol,
4-methyl-2-pentanol. The pre~erred alcohol is 2-methyl-2-
propanol, 2-butanol being more preferred and 2-propanol
being particularly preferred.
The preferred hydroyenated butadiene/isoprene/(meth)-
acrylonitrile copolymers according to the invention are
rubbers having glass transition temperatures below 0C and
preferably below -lO C, as measured for example mechanical-
ly/dynamically with induced vibrations at 11 Hz (Vibron
Viscoelastometer). They generally have Mooney viscosities
(DIN 53 523) in the range from 10 to 150, preferably in the
range from 20 to 100 and, more preferably, in the range
from 30 to 90 ML (1~4) 100C. The degrees of hydrogenation
are at least 85%, preferably between 90 and 99.7~ and, more
preferably, between 94 and 99.7%. The degree of hydrogena-
tion may be determined by NMR and IR spectroscopy.
on completion of hydrogenation, the reaction products
may be removed from the solution by standard methods,
Le A 27 581 9
2~929
including for example concentration by evaporation (optio-
nally under reduced pressure), injection of steam and
addition of a precipitant (non-solvent). The reaction
products may then be dried to remove residual solvent or
water.
The copolymers hydrogenated in accordance with the
invention are generally soluble in such solvents as, for
example, acetone, butanone, tetrahydrofuran, dichlorometh-
ane, trichloromethane and chlorobenzene.
For most applications, the hydrogenated copolymers
according to the invention are used in vulcanized form.
Vulcanization may be carried out, for example, by high-
energy radiation or by crosslinking with sulfur or sulfur
donors, with peroxides and optionally with polyfunctional
crosslinking compounds (such as for example triallyl
cyanurate, triallyl isocyanurate, bis-maleic imides,
divinyl benzene, methacrylates of polyhydric alcohols,
etc.), optionally after addition of fillers, stabilizers,
etc. Vulcanization with sulfur is preferred, in which case
copolymers hydrogenated in accordance with the invention to
degrees of hydrogenation of preferably 94 to 97% should
preferably be used.
Detailed descriptions of sulfur vulcanization systems
can be found in W. Hoffmann, "Vulkanisation und Vulkanisa-
tionhilfsmittel", Verlag Berliner Union GmbH, Stuttgart1965 and in Alliger and Sjothun, "Vulcanization of Elas-
tomers", Reinhold Pub. Corp., New York, 1964. Suitable
sulfur donors are thiuram polysulfides such as, for ex-
ample, dipentamethylene thiuram tetrasulfide and hexasul-
fide, tetramethyl thiuram disulfidei amine disulfides suchas, for example, dimorpholyl disulfide; sodium polysulfides
and thioplastics.
Preferred sulfur vulcanization systems contain
a) sulfur or sulfur donors,
b) optionally vulcanization accelerators and
Le A 27 581 10
2 9
c) optionally one or more activators.
a) is generally used in a quantity of 0.2 to 3.0% by
weight sulfur (in the case of sulfur donors, expressed as
the sulfur released), based on copolymer.
The vulcanization accelerator b) is generally used in
quantities of l to 3.5% by weight, based on copolymer.
Preferred vulcanization accelerators b) include thiazole
accelerators, such as 2-mercaptobenzothiazole (MBT), dib~nzo-
thiaz~ldi~ulfid~(MBTS),benzothiazyl-2-cyclohexyl sulfenamide
(CBS), benzothiazyl-2-tert.-butyl sul~enamide (TBBS), N-
morpholinothio-2-benzothiazole (MBS), benzothiazyl-2-
diisopropyl sulfenamide (DIBS), benzothiazyl-2-tert.-amyl
sulfenamide (rABS), benzothiazyl dicyclohexyl sulfenamide
(DCBS) and morpholinothiocarbonyl sulfene morpholide
(OTOS).
Other preferred vulcanization accelerators b) include
diphenyl guanidine (DPG) and di-o-tolyl guanidine (DOTG);
thiurams, such as thiuram mono- and disulfides; and
dithiocarbamates and also thiophosphates and derivatives
and salts thereof, for example zinc salts.
The most important activators c) are the metal oxides,
particularly zinc oxide. In individual cases, magnesium
oxide or calcium hydroxide is also used.
Preferred peroxides for peroxide vulcanization include
dial~yl peroxides, ketal peroxides, aralkyl peroxides,
peroxide esters, peroxide ethers; such as, for example, di-
tert.-butyl peroxide, bis-(tert.-butyl peroxyisopropyl)-
benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di-(tert.-
butylperoxy)-hexane, 2,5-dimethyl-2,5-di-(tert.-butyl-
peroxy)-hex-3-ene, 1,1-bis-(tert.-butylperoxy)-3,3,5-
trimethyl cyclohexane, benzoyl peroxide, tert.-butyl cumyl
peroxide and tert.-butyl perbenzoate.
The peroxide is preferably used in a quantity of 4 to
8% by weight, based on copolymer.
Vulcanization may be carried out at temperatures of
Le A 27 581 11
20~8929
100 to 200 C and preferably at temperatures of 130 to
180~C, optionally under a pressure of 10 to 200 bar. After
vulcanization, the vulcanizates may be post cured by storase
at el ev~t~d t~ripera ~ures .
"Vulcanized" in the context of the invention means
that less than 10~ by weight and preferably less than 5~ by
weight copolymer can be extracted by extractlon For 10
hours in a Soxhlet extractor using tetrahydrofuran followed
by chlorobenzene as extractant, the percentages by weight
being based on the copolymer used for extraction. The
expression "copol~vmer" means copolymer, i.e. it does not
include, for example, any extender oil present.
The hydrogenated copolymers according to the invention
are particularly suitable for the production of vulcani-
zates which have to be capable of withstanding severe
dynamic stressing. They may be used as seals, hoses,
membranes, drive belts, gaskets, cable sheaths, etc.
The parts and percentages in the following Examples
are by weight.
Examples
Pre~aration of mixtures
The mixtures were prepared from the following in-
gredients in a laboratory kneader which had been heated to
50~:
Parts by weight
Hydrogenated copolymer 100
Sulfur 0.5
Stearic acid
Zinc oxidel~ 2
Magnesium oxide2~ 2
~R~Vulkanox ocD3'
'R'Vulkanox ZMB-24) 0.4
Le ~ 27 581 12
20~929
Carbon black N 550 45
~Vulkacit thiuram5~ 2
Vulkacit CZ6) 0.5
-
" ~R~Zinkoxyd aktiv, a product of Bayer AG
2) (R)Maglite DE, a produet of Merek & Co. Ine., USA
3) Oetylated diphenylamine, a produet of Bayer AG
4) Zine salt of 2-mercaptobenzimidazole, a product of
Bayer AG
0 5) Tetramethyl thiuram disulfide, a product of Bayer AG
6) Benzothiazyl-2-cyclohexyl sulfenamide, a product of
Bayer AG
The hydrogenated eopolymer was introduced after the
sulfur had been incorporated on laboratory rolls (roll
temperature 50C). After 1 minute, all the constituents
apart from V u 1 k acit thiuram and V U 1 k acit CZ were added.
After another 3 minutes, the mixture was cooled to ap-
proximately 100C. The accelerator system was then incor-
porated and ejected after 1.5 minutes.
Vulcanization was earried Otlt in a press over a period
of 20 minutes at 160~C. The eompression set was determined
on a ~est sp~cimen I aecording to DIN 53 517 which had been
stored for 70 hours at -10C.
Examples I to 3
The following butadiene/isoprene/aerylonitrile eopoly-
mers were dissolved in ehlorobenzene to form 9.3% by weight
solutions and hydrogenated at 120C under a hydrogen
pressure of 150 bar in the presenee of 167 ppm Rh in the
form of RhCl [P(C5H5)3]3, based on copolymer. The hydrogena-
ted copolymers remained behind after removal of the sol-
vent.
Le A 27 581 13
2048~2~ -
Startin~ products for hydro~nation
Example Copolymerized Copolymerized
isoprene (%) acrylonitrlle (~)
1 ~.1 34.1
2 7.9 33.3
3 12.0 33.5
The hydrogenation results and the compression sets of
the hydrogenated copolymers are listed in the following
Table.
Le A 27 581 14
9 2 9
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