Note: Descriptions are shown in the official language in which they were submitted.
CA 02351961 2001-06-29
JUN-29-O1 12:50 Fron:BAYER SARNIA PATENT DEPT +519-339-1523 T-833 P.04/15 Job-
539
_._____ _.______._____ ...________ _________ _________ ~y, gr~aiacuiwr
'!'laightNitriia Rubbcr
Field of the Invention.
The present invention relates to nitrite rubber polymers having lower
molecular
~ weights and narrower molecular weight distributions than th4se known In the
art.
Back rou~.,~,.,nd o~~ the invention
Nitrite rubber (NBR), a co-polymer of a conjugated diene and an
unsaturated nitrite, is a specialty rubber whioh has very chemical resistance,
and
i0 excellent oil resistance. Coupled with the high level of mechanical
properties of the
rubber (in particular the high resistanoe to abrasion) it is not surprising
that NBR hoe
found widoapr~ad use in the automotive (seats, hoses, bearing pads),
electrical (cable
sheathing), mechanical engineering (wheels, rollers) and footwear industries,
amongst
others.
IS
Commercially available N6R is manufacture k>y e~uisiort polymerization. The
monomers are emulsified in water, a free radical-generating catalyst is added
and the
mixture is agitated whilst a constant temperature is maintained. After the
desired
degree of polymerization is reached, a shortstop and stabilizers are added to
the
ZO reaction system causing termination of the polymerization process.
Generally, NBR
obtained by this process has a Mooney viscosity in the Tango of from about 30
to about
94, an Mw in the range of from about 250,000 to about 350,000, an Mn in the
range of
from about 80,OC1n to about ~f50,060 and a pQlydispersify index greater than
about 3.2.
25 fn addition, so-called "liquid NBR" having a very 14w Mooney viscosity and
a low
molecular weight can be produced be adding the shortstop agent early in the
r$actian
process. As in the case of regular NBR, the resulting liquid N~Fi has a
poiydispersity
greater than 3Ø
3o Karl Ziegler's discovery of tip ~'fa..aos ~ ~ ~ae~#el sa~r~,s, 4r.
combination with main group alfcylating agents, to promote olefin
polymerization under
mild conditions has had a signifioant impact on chemical re9earch and
production to
date. It was discovered early on that some "~iagier-type'~caiaiystsmvt-only-p-
t~matr~tl~rrr----
1
CA 02351961 2001-06-29
JUN-29-O1 12:51 From:BAYER SARNIA PATENT DEPT t519-339-1523 T-833 P.05/15 Job-
539
proposed coordination-insertion mechanism but also effect an entirely
different
chemical process, that is the mutual exchange (or metathesis) reaction of
alkenes
R' R~ R~ R2
Catalyst
R-R R
Flgurs 1
Acyctic diene metathesis (or ADMET) is catalyzed by a great variety of
transition
metal complexes as well as non-metallic systems. Heterogeneous catalyst
systems
based on metal oxides, sulfides or metal salts were originally used for the
metathesis of
olefins. However, the limited stability (especially towards hetoro-
substituents) and the
lack of selectivity resulting from the numerous active sites and aide
reactions are major
drawbacks of the hatorogeneous systems.
1D
Homogeneous systems have also been devised and--u~d--to--gffect..ole#in ......-
.
metathesis. These systems offer significant activity and control advantages
over the
heterogeneous catalyst systems. For example, certain Rhodium based complexes
are
effective catalysts for thg metathesis of electron-rich olefins.
The discovery that certain metal-alkylidene complexes art capable of
catalyzing
the rnetathesis of olefins triggered the development of a new generation of
welhdeflned,
highly active, single-site catalysts. Amongst thes$, Bls-
(trlcyciahexylphosphine)-
penzylidena ruthenium dichlorider (commonly knew as Grubb's catalyst) has been
2o widely used, dus to its remarkable insensitivity to air and moisture and
high tolerance
towards various functi~anal groups- Unlike the molybdenum-based metathesis
catalysts.
this ruthenium carbene catalyst is stable to acids, aicohols, ai4ehydes and
quaternaiy
amine salts anal can be used in a variety of salvants (CBHB, CHzCl2. THF,
a'BuOH). The
most commonly-used catalysts are based on Mo, W and Ru.
The use of transition-metal catalyzed alkene metathesis has since enjoyed
increasing attention as a synthetic method. Research efforts have been mainly
focused
on the synthesis of small molecules, but the application of olefin metatnesls
to polymer
2
CA 02351961 2001-06-29
JUN-29-O1 12:52 Fraa:BAYER SARNIA PATENT DEPT +519-339-1523 T-333 P.OSflS .139
synthesis has allowed the preparation of new polymeric material with
unprecedented
properties (such as highly stereoregular poly-norbornadiene).
The utilization of olefin metathesis as a means to produce low molecular
weight
S compounds from unsaturated elastomers has received growing interest. The
principle
for the molecular weight reduction of unsaturated polymsrs Is shown in Figure
~. The
use of an appropriate cz~taiyst allows the cross-metathesis of the
unsatatr$tioc~-of--th$- -----
polymer with the co-olefin. The end result ie the cleavage df the polymer
chain at tho
unsaturation sites and the generation of polymer fragments Raving lower
molecular
i0 weights. In addition, another effect of this process is the "homogenizing"
of the polymer
chairs lengths, resulting in a reduction of the polydispersity. From an
application and
processing stand point, a narrow molecular weight distribution of the caw
polymer
results in improved physical properties of the vulcanized rubber, whilst the
lower
molecular weight provides good processing behavior.
!/
cac
__ __ ___ _ ________ __ __ _ _ __ ~g~_2 ~eie_ef pfatfy ~nsatureted Polymer
The so-call~d "dopalymeriaation" of copolymers of 1,S-fJUtadiens with a
variety of
cd-monomers (styrene, propane, divinylbenzene and ethylvinylbenzene,
acrylonitrile,
vinyltrimathylsilane and divinyldimethylsilane) in the presence of classical
Mo and W
catalyst system has been investigated. Similarly, the degradation of a nitrite
rubber
using WCh and SnMe4 or PhC~CH co,catalyst was reported in 1988_ However, the
focus of such research was to produce only low molecular fragments which could
be
characterized by conventional chemical means and contains no teaching with
respect to
3
CA 02351961 2001-06-29
JUN-29-01 12:53 Fro~:BAYER SARNIA PATENT DEPT +519-339-1523 T-B33 P.OT/15 Job-
539
the preparatlan of low molecular weight nitrite rubber polymers. Furthermore,
such
processes are non-controlled and produce a wide range of products.
The catalytic depofymeriaation of 1,4-palybutadiene in the presence of
substituted olefins or ethylene (as chain transfer agastts)-irt t~o-presenEe~f-
wei4-da#Ined--- --. ---
Grubb's or Schrock's catalysts is also possible. The use of Molybdenum or
Tungsten
compounds of the general structural fmmuia {t~(~hifp)tC~ftz3at~~3T ~ _ ~~ W
produce low molecular weight poiymara or oligamer~ from gelled polymers
containing
internal unsaturation along the polymer backbone was claimeri-in-
U~'rF;~4fi;1G2: Again;
!o however, the process disclosed is non-controlled, and there is no teaching
with respect
to the preparation of law malecrLtlar weight nitrite rubber polymers.
Summarx of the Inventlan
We have now discovered that a low molecular weight nitrlle rubber having
narrower rnalecular weight distributions than those known in the art can be
prepared by
olefin metathesis. Rubbers having a narrow molecular walght distribution have
certain
advantages over those having a broad molecular weight dlstrlbutian, one of
th~ase being
that they have improved physical properties, resulting, for example, in better
prooesaability of the rubber.
Thus, one aspect of the disclosed invention is a nitrite rubber having a
molecular
weight (Mw) in the range of from about 25,000 to about 2Gu,uDir, r~ Moonay
viscositg-- -----
(MI- 1 t~l i 00) of less than about 25, and a MW D (or polydispersity index)
of less than
about 2.5.
pescription of the Invention
As used throughout this specification, the term "nitrIle rubbed" is intended
to have
a broad meaning and is meant to encompass a copolymer of a conjugated dlene
and
an unsaturated nitrite.
The conjugated diene may be a C4-C6 conjugated diene. Non-limiting examples
of suitable such conjugated dienes may be aeleoted from the group comprising
butadiene, isoprene, piperylene, 2,3-dimethyl butadiene and mixtures thereof.
The
preferred Ce-Ce conjugated dlene may be selected from the group comprising
4
CA 02351961 2001-06-29
JUN-29-01 12:58 Fram:BAYER SARNIA PATENT DEPT +519-339-1523 T-934 P.09/15 Jab-
539
butadiene, isoprene and mixtures thereof. The most preferred ~'-CR conjugated
diene
is butadiene.
The unsaturated nitrite may be a C3-Cs a,~-unsaturatad nitrite. Nan-limiting
examples of suitable such C3-Cs a,~~unsaturated nitrites may ba selected from
the
group comprising acrylonitrile, mathacrylonitrile, ethacrylonitrlle and
mixtures thereof.
The most pref~rred C3-Cs a,~-unsaturated nitrite is acrylonitrile.
Preferably, the copolymer comprises from about 40 to about 85 weight percent
of the copolymer of bound conjugated diene and from about 1 S to about GO
weight
peroar<t of the copolym~ar of bound unsaturated nitrite. More pref~9rably, the
copolymer
comprises from about 60 to about 75 weight percent of the copolymer of bound
conjugated diene and from about 25 to 2~bout AO weight percent of the
copolym9r of
bound unsaturated rlitrile. Mast preferably, the copolymer comprises from
about BO to
about 74 weight percent of the copolymer of bound aanjugatad diene and from
about
30 to about 40 weight percent of the copolymer of bound unsaturated nitrite.
Optionally, the copolymer may further comprise a bound unsaturated carboxylic
acid. Non-limiting examples 4f suitablQ such bound unsaturated carboxylic
acids may
ba selected frr~m the group comprising fumario acid, maleia acid, acrylic
acid,
methscrylio acid and mixtures thereof. The bound unsaturated carboxylic acid
may be
present in an amount of from about 1 to about 10 weight percent of the
copolymer, with
this amount displacing a corresponding amount of the conjugated diolefin.
Further, a third monomer may be used in production of the nitrite polymer.
Preferably, the third monomer is an unsaturated mono- ar di-carboxylic acid or
derivative thereo#-{~r g-.; ester; arnidos-and- the-like~).-
The metathesis reaGtian can be catalysed by compounds of formula I, II ar.lll:
as
shown below
5
CA 02351961 2001-06-29
JUN-29-01 12:59 From:BAYER SARNIA PATENT DEPT +519-339-1523 T-834 P.09/15 Job-
539
L
X~ ~ -... ~Fi
~M C'
Xt ~ '~Ri
L~
Formula I
wherein:
M is 4s Qr Ru;
R and R' are, independently, hydrogen or a hydrocarbon selected f~oin the
group_consisting of C~-Coo alkenyl, Ca-Gzo alkynyl, C~-C?fl alkyl, aryl, Ci-
Coo carboxylate,
Ci-Czo alkoxy, C2-Coo alkenyloxy, Cz-C2o alkyrtyloxy, aryloxy, Cz-C~
alkoxycarbonyl, C~_
C2o aikylthio, C1-C~ alkylsulfonyl and Gi-C~zo alkylsulfinyl;
X and X' are independently selected anionic ligands; and
L and L' are, independently, ligands selected from the group consisting of
1o phosphines, sulf4nated phosphinea, fluorinated phosphines, functlonallzed
phosphlnes
having up to three amlnoalkyl-, ammonlumalkyl-, alkoxyalkyl-,
alkoxykx~rbonylalkyl-,
hydrocycarbonylalkyl-, hydroxyalkyl- or ketoaikyl- groups, phosphites,
phosphinites,
phosphonitaa, phosphinaminos, arcinas, stibine$, ethers, amines, amides,
imines,
sulfoxides, thiaethers and pyridines; optionally. L and L' can be linked to
one another to
from a bidentate neutral (igand wherein at least one of the above-mentioned
functional
groups is present.
Lz Ra
M'-"~ G~ C~ C
xa/
3
L3 R
Formula II
wherein:
2o M' is Os or Ru;
R2 and R~ are, independently, hydrogen or a hydrocarbon selected from the
group
consisting of C~-Coo aiker~yi, Cz-C~ alkynyi, Ct-G~ alkyl, aryl, C~-Cue,
carboxylat~e, Ct_
6
CA 02351961 2001-06-29
JUN-29-01 13:00 Fron~:BAYER SARNIA PATENT DEPT +519-339-1523 T-834 P.10/15 Job-
539
C~ alkoxy, C2-~~ aikenyloxy, Gz-Cao alkynyloxy, aryloxy, C~-C2o
alkoxycarbonyl, C~-C2o
alkylthio, C1-Cao alkylsulfonyl and C,-G2o alkyl5ulf inyl;
X2 is selected from any anionic ligand; and
L2 is a neutral n-bonded ligand, preferably but not limited to arena,
substituted
arena, heteroarene, independent of whether they are mono- or polycyclic;
L3 is a Ilgand selected from the group consisting of phosphines, sulfonated
phosphines, fluorinated pllospnlnes, functlonallzed phosphlnes bearing up to
three
amino&Iltyl-, ammoniumalkyl-, alkoxyalkyl-, alkoxylcr~rbanylalkyl-,
hydrocycarbonylaikyl-,
hydroxyalkyl- or ket4alkyl- groups, phasphites, phosphinites, phosphonites,
ip phcsphlnamlnoe, arsines, stibenQS, ethers, amines, amides, (mines.
sulfoxidas,
thioethers and pyridines;
Y' is a non-coordinating anion;
n is an integer in the range of from 0 to 5;
f~R~2
~R
2-
OR 2-M ~C~
Ra
N
s
R
i5 Formula III
wherein
M2 is Mo or W
R4, Rs are, independently, hydrogen or a hydrocarlaort selected frorrs tl~e
group
consisting of C2-Coo alkenyl, Ca-Cao aikynyl, Cy-Cao alkyl, aryl, C,-C2o
carboxylate, Ci
20 C~ alkoxy, Cz-Cao alkenyloxy, C2-C2o alKynyloxy, aryloxy, Ga-C2o
alkoxycarbonyl, C,-C2a
alkylttllo, C1-C2o alkylsutfonyl and C~-G~ a+kylsu6#'+nyl;
R6 and »' are independently selected from any unsubstitutQd ar halo-
substituted
alkyl, aryl, aralkyl groups or silicon-containing analogs thereof.
25 r~atalysts of Formula I are preferred. More preferably, catalysts of
Formula I
wherein L, and 1-1 are trialkylphosphines, X and X' are chloride ions anti IUI
is Ruthenium
are preferred.
7
CA 02351961 2001-06-29
- JUN-29-01 13:00 From:BAYER SARNIA PATENT DEPT +519-339-1523 T-834 P.11/15
Job-539
The amount of catalyst employed in the metathesis reaction will depend upon
the nature and activity of the catalyst in question. 'Typically, the ratio of
catalyst to NBR
is in the range of from about d.OgS to about 5, preferably in the range of
from about
S 0.025 to about 1 and, more preferably, in the range of from about 0.1 to
about 0.5.
Tne metathesls reaction Is carried out in the presence of a co-olefin which is
a C,
to Cia linear or branched olefin such as ethylene, isobutene, styrene or 1-
h~xane.
Where the co-olefin is a liquid (such as 1-hexane), the amount of co-olefin
employed is
1o in tho range of from about 1 to about 50 weight %; preferably in the ran06
of from about
to about 30 weight %. Where the oo-olefin is a gas (such as ethylene) the
amount
-- ' ~~ - of co-oletiri-evripidjrod-is such-ti~lar-it-results-inw-presst~rawin
thwr~action vessel in the
range of from about 15 to about 1540 psi, preferably in the range of from
about 75 to
about 600 psi.
The metathssis reaction can be carried out in any suitable solvent which does
not inactivate the Catalyst or otherwise intertere with the reaction.
Preferred solvents
include, but are not limited to, dichloromethane, benzene, toluene,
tetrahydrofuran,
cylcohexana and the likd. The moat preferred solvent is monochlorobenzena
(MCB).
In curtain cases th~ ca-of~fin can itself act as a solvent (for example, 1-
hexane). in
which case no other solvent is necessary.
The concentration of N6R in the reaction mixture is not critical but,
obviously,
should be such that the reaction is not hampered if the mixture is too viscous
to be
2~ stirred efficiently, for example. Preferably, the concentration of.":~~:-
ia.-1n .the r:nge-of"~- "
from about 1 to about 20%, most preferably in the range of from about 6 to
about i 5%.
The metath98is reaCtiOr~ Is carried out at a temperature In the range of from
about 20 to about 140qC; preferably in the range of from about 80 to about
120$C.
The reaction time will depend upon a number of factors, including cement
concentration, amount of catalyst used and the temperature at which the
reaction is
performed. The metathesis is complete within the first two hours under typical
conditions. The progress of the metathesis reaction may ba monitored by
standard
analytical techniques, for example using C PC or solution viscosity .
8
CA 02351961 2001-06-29
JUN-29-01 13:01 Fro~:BAYER SARNIA PATENT DEPT +519-339-1523 T-834 P.12/15 Job-
539
The Mooney viscosity of the rubber was determined using AaTM test D164B.
Por a typical product the Mn is about 30,000 (compared to about 85,D00 far the
starting polymer) whilst the Mw is about 65,000 (compared to 300,040 for the
starting
polymer. As can be seen from Table 1, however, higher molecular weights (Mw)
can
also be obtained by manipulation of the experimental conditions (for example
by
loworing the catalyst loading). As expected, the molecular weight distribution
fall9 from
about 3.5 for the starting NMB feedstock to about 2.0 for the metatheslzed
product.
This is consistent with a more homogeneous range of polymer chain lengths and
malQCUlar wQights.
A summary of the polymer properties for selected samples is shown in Table 1.
The GPC results show up to a fivefold reduction in Mw arid a narrowing of the
polydispersity index to about 2Ø
is
Table 1 Summary of Polymer Praperkles
MN MW MZ PDI Mooney Vi9oosity
(ML i+4 ~ ~~;
Starting N6R 86000 268000 839000 3.60 35
(Parbunan)
Experiment 1 27000 54000 9204Q 2.00 2.5
Experiment 2 27000 b3000 890D0 1.98 -
Experlment 3 32000 66000 117040 2.06 -
F-~cperiment 4 67000 134000 253000 2.00 -
Exporrlmental Details
Ris(tricyolohexylphosphino)banzylidene ruth~nium c#iohloride (Crubb's
metathesis catalyst), 1-hexen~.and monochlorobanzene (MGS) were purchased from
Alfa, Aldrich Chemicals. and PPG respectively and used as received. Perbunan
was
obtained from Bayer Inc. .
9
CA 02351961 2001-06-29
- JUN-29-01 13.02 Fron~:BAYER SARNIA PATENT DEPT +519-339-1523 T-834 P.13/15
Job-539
The metathesis reactions wars
carried out in a Parr high-pressure
reactor under
the following conditions:
Cement Concentration 6 or 15%
Co-Oiefin Ethylene or 1-Hexena
Co ~Ofefin Concentration Variable
Agitator Speed soo rpm
Reactor Temperature Variable
Catalyst Loading Variable
Solvent Monachlorobenzene
1o Substrate Perbunan NT 3435 T
Perbunan NT 3429 T
In a typical lab experiment, 200g of rubb~r was dissolved in 1133g of MCB (15%
solid). The cement was then charged to the reactor and degassed 3 times with
C~H4
15 (l00 psi) under full agitation. The reactor was heated to desired
temperature and BomL
of a monachlorobenzene solution containing Grubb's catalyst was added to the
reactor.
The temperature was rnalntained constant for tile duration of the reaction. A
cooling
coil connected to a temperature controller and a thermal sensor was used to
regulate
the temperature. The progreaa of the reaction was monitorQd using solutlan
viscosity
20 moacurements for the 6°/q cQments. At higher cement concentration.
the reaction was
assumed to be complete after 18 hours.
