Note: Descriptions are shown in the official language in which they were submitted.
~3711
CATALYST, ITS PREPARA~ION AND ITS USE FOR THE
POLYMERISATION OF CONJUGATED DIENES IN SOLUTION
This invention relates to a new homogenous
catalyst, its preparation and its use for the polymeri-
sation o~ conjugated dienes in solution to produce polymers
which have a good tack.
Polybutadiene containing a high proportion
of cis-l,4-units has been in procluction on a large
commercial scale for some time and is used for the
manufacture of tyres and other rubber products.
The organometallic mixed catalysts used for the
process contain titanium, co'balt or nickel compounds
as their transition metal components. One of the
various disadvantages of polybutadiene produced with
the aid of these catalyst compared with natural rubber
is its low tack.
Although catalysts for the production of
polybutadiene having improved tack are
known, the products have other serious disadvantages
which have prevented their commercial application.
In a publication which appeared in "Kautschuk
und Gummi, Kunstoffe", year 22 No. 6/1969, for e~ample,
a catalyst is described on pages 293 et seq which can
be used to produce a polybutadiene havin~ a ~ood
tack. The catalyst system described in that
publication consists of:-
l. an aluminium alkyl or alkyl aluminium hydride,2. ceroctoate and
3. a halide compound.
The cerium compound used has the disadvantage
of being only slightly soluble in the solvents used
for the preparation of the catalyst and for the
polymerisation of butadiene. ~he finished ca~alyst-
also fails to form a homogeneous solution. Both the
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cerium compound and the catalyst obtained ~rom it are
there~ore difficult to measure out precisely in a
commercial process, although this would be very
important ~or a smooth progress of the reaction and
consistent product properties. Moreover, when used
ior the polymerisation of dienes in solution, hetero-
geneous catalysts have a strong tendency to -~orm gels,
which is undesirable and may cause encrustation of
reaetion vessels and stirrers and blocking of pipes,
which may lead to considerable interierenee with the
production process in a commercial plant.
It is mentioned in the same publication, on-
page 297, column 2, line 3, that other rare earth
metals probably also form catalysts having similar
properties.
The use of compounds o~ the rare earths as
components or organometallic mi~ed catalysts ~or
polymerisation reactions has, in fact, been known for
a long time. U.S0 Patent No. 3, 118, 864, for example,
claims a eatalyst for -the polymerisation of butadiene,
isoprene or chloroprene, which catalyst is formed by
the reaetion of an ester or halide of eerium with
an organometallie eompound having at least one metal-
earbon bond.
Another catalyst which is suitable for the
stero-speei~ie polymerisation o~ dienes is described
in German Auslegschrift No. 1,302,264. It consists
o ~ :--
a) a chelatohalide o~ a metal group IIIB of the
periodic system of elements and
b) an aluminiu~ trialkyl or alkyl aluminium hydride.
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-- 3 --
The above-mentioned Patent also mentions
catalysts which are prepared from:-
a) a soluble chelate of a metal of group IIIB,
b) an alkyl aluminium halide ancl
5 c) an aluminium trialkyl or alkyl aluminium hydride.
All the catalysts described also have
the disadvantages mentioned ab~e, that is to say they
consist of solids which are insoluble both in monomers
and in solvents which are suitable for the polymerisation
10 o~ dienes.
It is therefore also polnted out in the above-
mentioned publication (column 7, lines 16 - 20) that
when polymerisation is carried out in organic solvents,
the polymer is obtained "in a swelled, agglomerated
state".
Such products do not have good properties in
terms of rubber technology. Polymerisation using
these catalysts is therefore preferably carried out in
a solvent-free manner but the use oY an inert solvent
is desirable for a process carried out on a large
commercial scale in order that the heat liberated by
polymerisation may be removed more effectively.
It is therefore an object of the present
invention to provide a catalyst for the polymerisation
2~ of conjugated dienes, preferably butadiene which is ccmpletely soluble
in the solvent used and with which it is possible to produce a poly-
mer which has good properties in terms of rubbertechnology, in particular a high tack.
Another object of the present invention is
that all the catalyst components added to the polymeri-
sation solution should be soluble in an inert solvent.
Yet another object of the present invention
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is that the catalyst used should have a very high
activity for the polymerisation of conjugated dienes even
when present in only small quantities.
Certain catalysts suitable for the poly-
merisation of butadiene have now been found which donot have the disadvantages descr:ibed above and solve
the problem underlying the present invention.
The present invention -thus relates to a
catalyst consisting ~ :-
10 A) a rare earth carbo~ylate corresponding to thefollownng general formula:
Rl
M (R2- C - C02 )
\ R3 / 3
B) an aluminium alkyl AIR4 and/or R2AlH
C) a Lewis acid,
wherein in the general formulae
M represents a trivalent rare earth element
having an atomic number of from 57 to 71,
R ,R , and R3, which may be the same or different,
represent alkyl groups having from l to lO
carbon atoms, the sum of the carbon atoms
present in Rl, R2 and R3 being from 6 to 20
and
R represents a straight chain or branched chain
alkyl group having from 1 to lO carbon atoms.
Compounds A, composed of trivalent cations of
the rare earths and the acid group of tertiary carboxylic
acids corresponding to the following general formula:-
R
R - ~ - C02H
R
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are readily soluble in hydrocarbons.
This finding is surprising since other rare
earth carboxylates, e.g. the acetates, propionates,
hexane carboxylates, triethyl acetate, 2-methyl-hexane
carboxylates, 2-ethyl-hexane carboxylates, palmitates,
stearates, benzoates and phenyl acetates, are only
slightly soluble in apolar organic solvents.
The symbol M in component A represents a
trivalent rare earth element having an atomic number
of from 57 to 71 in the periodic system. It is pre~erred
to use those compounds in which M represents lanthanum,
cerium, praseodymium or neodymium or a mixture o~
rare earth elements containing at least one or the
elements, lanthanum, cerium, praseodymium or neodymium,
in an amount of at least lOC/o by weight.
Compounds in which M is lanthanum or neodymium
or a mixture o~ rare earth elements containing at least
30 ~ by weight lanthanum or neo~mium are pa~cularly preferred.
~l, R2, and R3 each represent an alkyl group
having from l to lO carbon atoms, the sum of all the
carDon atoms present in the substituents R', R2 and R3 being from
6 to 20, preferably from 7 to 14. Examples of acids
from which carboxyl groups R1, R2, R3 - CCO2 may be
derived include the following carboxylic acids:-
2-methyl-2-ethyl-pentanoic acid,
2,2-diethyl-pentanoic acid,
2,2-dimethyl-hexanoic acid,
2-methyl-2-ethyl-hexanoic acid,
2,2-diethyl-hexanoic acid,
2-ethyl2-propyl-hexanoic acid,
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2-ethyl-2-butyl-heptanoic aeid,
2,2-diethyl heptanoic acid,
2,2-diethyl-oetanoic aeid, and
2-methyl-2-butyl-octanoic acid.
Mixtures of the above-mentioned carboxylic
acids are also suitable as carboxylates of component A.
The following are examples of suitable rare
earth carboxylates:-
lanthanum-tris-(2,2-diethyl-heganoate),
10 praseodymium-tris-(2,2~iethyl-hexanoate),
neodymium-tris-(2,2-diethyl-he~anoate~
lanthanum-tris-(2,2-diethyl-heptanoate),
praseodymium-tris-(2,2-diethyl-heptanoate),
neodymium-tris-(2,2-diethyl-heptanoate),5 lanthanum versaticate (lanthanum salt of versatic acid,
a trade produc$ of Shell Chemicals);
praseodymium versaticate, and
neodymium versatieate.
In the fon~ae AI~ and ~ of component s, the symbol
20 R4 represents a straight ehain or branched chain alkyl
group having from l to lO earbon atoms. The following
are e~amples of suitablealuminium alkyls:-
trimethyl aluminium,
triethyl aluminium,
25 tri-n-propyl aluminium,
triisopropyl aluminium,
tri-n-butyl aluminium,
triisobutyl aluminium,
tripentyl aluminium,
30 trihexyl aluminium,
tricyclohe~xyl aluminium, and
trioctyl aluminium~
114;3~
-- 7 --
di-ethyl aluminium hydride,
di-n-butyl aluminium hydride
di-iso-butyl aluminium hydride.
Triethyl aluminium, triisobut~1 aluminium and di-iso-
5 butyl aluminium hydride are preferred. Triethyl aluminium
is particularly preferred.
So called Lewis acids are used as component
C.
These may be e~emplified by the organometallic
halides in which the metal atom belongs to the main
group 3 a) or 4 a) and by halides of elements of the
main groups 3 a), 4 a) and 5 a~ of the periodic system,
as indicated in the "~andbook of Chemistry and Physics",
45th Edition, 1964-65:-
methyl aluminium dibromide,methyl aluminium dichloride,
ethyl aluminium dibromide,
ethyl aluminium dichloride,
butyl aluminium dibromide,
butyl aluminium dichloride,
dimethyl aluminium bromide,
dimethyl aluminium chloride,
diethyl aluminium bromide,
diethyl aluminium chloride,
dibutyl aluminium bromide,
dibutyl aluminium chloride,
methyl aluminium sesquibromide,
methyl aluminium sesquichloride,
ethyl aluminium sesquibromid0,
ethyl aluminium sesquichloride,
dibutyl tin dichloride,
aluminium tribromide,
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antimony trichloride,
antimony pentachloride,
phosphorus triehloride,
phosphorus pentachloride, and
tin tetrachloride.
Diethyl aluminium chloride, ethyl aluminium
sesquichloride, ethyl aluminium dichloride, diethyl
aluminium bromide, ethyl aluminium sesquibromide and
ethyl aluminium dibromide ~xe preferred.
As eomponent C reaetion produets of alkylaluminium
eompounds and halogenes, sueh as triethylaluminium and
bromine, ean also be used.
The molar ratio in which the catalyst com-
ponents are used may vary within wide limits.
The molar ratio of component A to component
B may range from l:l to l:lO0 and is preferably in the
range of from l: 3 to l:80, most pre~erably from l:3
to l-50. The molar ratio of component A to component
C is in the range of from 1:0.4 to 1 15, prefexably
20 from 1 0.5 to 1:8.
Another object of the present invention is a
process for the preparation of the catalyst. The
eatalyst may be prepared by mixing the solutions of
components A,B and C in any sequence in a su table
25 inert solvent with stirring. Suitable solvents include
e.g. aromatic, aliphatic and cycloaliphatic hydrocarbons
sueh as benzene, toluene, pentane, n-hexane, isohexane,
heptane and cyclohexane and mixtures thereo~. The
catalyst may, for example, be prepared with the same
30 solvent as that used for the polymerisation of dienes.
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The temperature at which the catalyst is prepared may
vary within a wide range and is generally limited by the
melting or boiling point of the solvent used. Temp-
eratures in the range o~ from -30C to 80C, for e~ample,
5 are suitable. The catalyst may be prepared separately
but is preferably prepared by adding the catalyst
components A,B and C and mixing them with the poly-
merisation mi~ture. Components A and B or components
B and C may be mi~ed together be-~ore they are added
10 to the polymerisation components. It is immaterial
whether the diene which is to be polymerized is
added before or aiter the catalyst components or
whether the diene is added between the addition
of two catalyst components. The iollowing are e~amples
15 oi sui-table sequence used whe~-the catalyst is prepared
by mi~ing the components in with the polymerisation
mixture:-
l. solvent,
2. diene,
3. component A,
4. component B,
5. component C, or
l. solvent,
2. component A,
3. component B,
4. component C,
5. diene, or
l. solvent,
2. component B,
3. component C,
~. component A,
5. diene.
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Catalyst components A,B and C may, if desired,
be added simultaneously to the solvent-monomer mixture.
The catalyst has a high activity and very small
quantities are therefore sufficient to produce a catalytic
effect. The quantity of catalyst used is generally
from O.Ol to 0.5 m Mol, based on component A, to lO0 g
of monomer. -- -- `-~~-
Another object of the present invention is theuse of the catalyst according to the present invention
10 for the homo- or co-polymerisation of dienes in solution.
The polymerisation of the diene is generally
carried out in organic solvents. These must be inert
towards the catalyst system used. Suitable solvents
include aromatic, aliphatic and cycloaliphatic
15 hydrocarbons such as benzene, toluene, pentane,
n-he~ane, isohexane, heptane and cyclohexane.
Polymerisation ~sing the catalyst according
to the present invention may be carried out either
continuously or batchwise.
~ It is preferably carried out at a temperature of from
-20C to 150C, preferably from 0C to 120C.
In one conventional method, components A, B
and C are added to a mi~ture of lO0 parts by weight of
solvent and from 5 to 40 parts by weight, preferably
from 8 to 20 parts by weight of butadiene. Poly-
merisation starts at once, as can be recognised by
the evolution of heat. When the quantity of catalyst
used is Q.06 mMol, based on component A, and the
temperature is about 90C, conversions of more than
30 30% by weight are obt~ned after a reaction time which may ~y
from 30 minutes to 5 hours.
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~ hen the desired degree o~ conversion has
been reached,the catalyst is inactivated by the addition
of small quantities of, ~or example, water, carboxylic
acids or alcohols.
The conventional stabilizers may be added to the
polymer solution in the conventional quantities beiore
the product is worked up. The stabilizers used may
be, ~or example, sterically hindered phenols or aromatic
amines such as 2,6-di-tertiary butyl-4-methyl-phenol.
1 The polymer may be isolated by evaporation of the
polymer solution, precipitation wit~ a non-solvent as
methanol, ethanol or acetone or, pre~erably by steam
distillation of the solvent. The polymer may be dried
by conventional methods, e.g. in a drying cupboard
or drying screw.
The polybutadiene prepared according to the
present invention contains a proportion oi cis-l,4
double bonds of, for example, irom 80 to 99%. Its
building tack is considerably improved compared with
that of the known trade products. Pre~erred uses are
for motor car tyres and tech~al rubber articles.
The present invention will now be illustrated by the
following Examples in which all the percentages quoted
represent percentages by weight unless otherwise indicated.
25 Example l --
The ~ollowing components were introduced at
40C into a stirrer vessel of 40 litres capacity after
it had been flushed with nitrogen:
l. 25 litres cyclohexane,
30 2. 2.6 kg butadiene,
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3. 2.0 mMol neodymium versaticate dissolved in 50 ml
cyclohexane,
4. 80 mMol triethyl aluminium dissolved in 50 ml cyclo-
hexane,
and
5. 2.0 mMol ethyl aluminium sesquichloride dissolved
in 50 ml cyclohe~ane.
The reactor was surrounded by a jacket through
which water could be conducted at a temperature of ~rom
15 to 90C. The polymerisation mixture was thereby
heated to 75C and maintained at this temperature.
~he reaction was stopped after 3 hours by
the addition of ethanol. After the addition o~ 0. 3%
of 2,6;-di-tertiary butyl-4-methylphenol (based on
solid polymer) as a stabilizer, the polybutadiene
was obtained by removal of the cyclohe~ane by steam
distillation.
The polymer was dried in a vacuum at 50C.
The yield was 98~, based on the monomer used.
IR analysis: 1,4 cis - 95.3%; 1,4 trans = 4.1%;
~ 1,2 = o.60/o.
E~ample 2
Using a stirrer vessel of 40 litres capacity
which had been rinsed with nitrogen, a catalyst was
prepared by the following method at 20C:
1. 25 litres of cyclohe~ane,
2. 60 mMol of triethyl aluminium dissolved in 100 ml
of cyclohe~ane~
3. 2.4 mMol of ethyl aluminium sesquichloride and
4. 2.0 mMol o~ neodymium versaticate, dissolved in
50 ml of cycloheæane.
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Stirring was conti~ued for lO minutes a~ter
the addition o~ the last component. 2. 6 kg of
butadiene were added to the prepared catalyst solution.
Polymerisation was carried out at 70C. The reaction
was stopped after 2-~- hours by the addition o~ a solution
o~ 20 g o~ stearic acid in 2 litres of cyclohe~ ne,
and the reaction mi~ture was worked up as described in
Example l.
The yield was 960/o~ based on the monomer put
into the process.
IR analysis: l,4 cis = 96. 3%; l,4 trans = 3.1%;
1,2 = o.60/o.
The polymer had the following properties:
Intrinsic Yiscosity: ~. 63 dl/g
Mooney viscosity: (ML-4', lOO): 41
Defo hardness (~0C): 575 p
Defo elasticity (80C): 23%.
The polymer was mi~ed on rollers and then cured.
The m~ture and the vulcan~sate were tested by comparison
with a commercial type of polybutadiene obtained using
a titanium catalyst.
The followimg ~ormulation o~ mixture was used: -
Polybutadiene lOO parts by weight
carbon black (N 330 )50 parts by weight
25 aromatic oil 5 parts by weight
ZnO 3 parts by weight
Stearic acid l.5 parts by weight
N-i sopropyl -N t -phenyl'p-phenylene
diamine l.O parts by weight
30 phenyl-~ -naphthylaminel.O parts by weight
benzothiazyl-2-sulphene morpholide l.O parts by weight
sulphur l.5 parts by weight.
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When the mixtures were prepared on rollers,
distinct defects in processing characteristics were
observed in the trade product used -for comparison,
particularly at a temperature above 40C.
In comparison, the polybutadiene prepared
according to the present invention still had excellent
processing characteristics at a temperatu~e up to 70C.
A smooth rolled sheet having neither holes nor tears
was immediately formed. The sheet remained smooth
and unbroken even after the addition of the mixing
components. ~he sheet did not lift off the rollers.
In contrast to the known trade products, the
polybutadiene prepared using the catalyst according
to the present invention is distinguished by its
excellent building tack.
~3~
A catalyst was prepared by mixing l.78 ml
of the solution of 0.08 mMol of neodymium versaticate
in cyclohexane, 40 ml of cyclohexane and 2.4-ml of a
molar solution o~ Al(C2H5)3 in cyclohexane with the
exclusion of air and moisture and then adding o.6 ml of
a O.l molar solution of (C2~5)3A12C13 in cyclohe~ane.
Polymerisation was carried out in a glass
flask of 500 ml capacity. After the flask had been
rinsed with nitrogen, 290 ml of cyclohexane were
introduced simutaneously with nitrogen, and nitrogen
then continued to be introduced into the li~uid
for a further 2 minutes. The flask was then closed in
an air-tight manner with a rubber bung and a metal
crown cork which had apertures for the introduction
of injection needles.
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25 g of liquid monomer were introduced into
! the flas~ from a cylinder containing butadiene by
means ~f an injection needle. 14 ml of the catalyst
solution were added from a syringe to which an in-
jection needle was attached. The flas~ was placed in
a heating ~ath at 60C for 2 hours. The cork was then
removed and the polymer precipitated with Or 5 lit~es
o~ ethanol to ~hich a small quantity of an antioxident
I had been added.
¦ 10 The coagulated polybutadiene was dried to
a constant weight in a vacuum at 5OC. The yield was
22 g (88~o).
Example 4
Along the procedure described in Example 3 the follo-
15 wing components have been added into a glass flask:
1) 290 ml Cyclohexane, 2) 40 g isoprene, 3) 0.6 mMol
~` Al(C2H5)3, 4) 0,2 mMol iC2H~)2 AlBr and 5) 0.08 mMol
; - Nd (vers)3.
The reaction time is 2,5 h at 60C. The polymer has been
20 worked up as described in Example 3. 39,6 g (99 %) of
polyisoprene has been obtained.
Example 5-9
Along the procedure described in Example 3 the follo-
wing components have been added into a glass flask.
25 1) 290 ml Cyclohexane, 2) butadiene, 3) component B,
4) component C and 5) component A.
In Example 8 the reaction product of Al (C2H5)3
dissolved in Cyclohexane and bromine has been added as
component C.
In Example 9 didymversaticat (di-vers3) has been added as
component A. Didym(di) stands for a mixture of the rare
earth metals as follows: 72 % neodyme, 20 % lanthane
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- 16 -
and 8 % praseodyme.
The ~rking up step took place along the description
of Example 3. The conditions for polymerization as well
as the respective results are summarized in table 1.
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~ a~ ~D ~D ~ ~r I
~ ~9 oo ~r u~ ~
u~ ~ cn ~ ~ a~
U
_ ~ ____ _ .
o o o~
I`
dP ~ . ~ a~ a~
.
N N N
O O O ~0 O
~U ~D ~D_ .
~ U~ U~ _ _ _
~ ~ s~ ~ ~ a~ ~ a) u~ ~ ~
a~ ~ o ~ ~ o ~ o ~ o
o~ z o -- æ o z o -~ o
N
~) ~lr) ~1~ m m
U N t~ U ~ Ir) ~ N
u~ ~ ~D ~ ~ In ~ ~
' ~ O ~ O ~ O ~ ~- ^ O
~ ~ ~) ~ ~') ` ~ ~ N ~ 11'1
~ û~ o~ 5U~ O U O 3~ 0
~ ~ ~ I¢ C)
C~ _
. - _.
m ~:
C ~1 ~ __ N
In Lr ~ U~ U~ U~
~ ~ ~ X a~ ~C ~ ~:
O ~N ~ N Ifl ~ N Ir) N 1~ N ~1
~ c) o ~ ~ u~r ~ ~ ~ C~ ~1 C.~
C,) ~ ~ O I O ~ O ~ O ~ O
_
--O N 10
rl ~ ~ N r~ In
N N ~ N N
~_ ~_ . .... ,. . ~.... . ,. __
~ x e u~ ~9 .
E-l ~3 ~ r~ c~
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18 -
Example 10
Along the procedure described in Example 3 hutadiene
and isoprene are copolymerized. Into a glass flask the
following components are added in the following sequence:
1) 290 ml cyclohexan, 2) 19.6 g isoprene,
3) 19,4 g butadiene, 4) 0.45 mMol Al(C2H5)3,
5) the reaction product of 0.15 mMol bromine and
6) 0,06 mMol neodyme versaticate.
The polymeriæation took 2,5 h at 60C. The working
up procedure is the same as in Example 3. The yield of
the polymer is 83 %.
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