Note: Descriptions are shown in the official language in which they were submitted.
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Linear block polymers of the idealized form S -By~Sz, in which S
represents a structural unit derived from styrene, B represents a structural
unit derived from a conjugated diene (butadiene or isoprene) and x, y and z
represent integers, are already known. They are used as thermoplastically
processible elastomers (Gummi, Asbest, Kunststoffe, 5, 1973, 387).
Block polymers of the idealized form SX-B (the symbols having the
same meaning as defined above) are also known. Block polymers of this kind
are likewise denoted as "diblock copolymers". Their technological value is
only small. They are obtained inter alia by polymerizing styrene and a
conjugated diene (butadiene or isoprene) on lithium catalysts in the form of
"living polymers", i.e. polymers which, following the addition of further
monomers, continue polymerizing in tlle absence of fresh catalyst, unless
they have been previously deactivated.
According to DT-AS 1,245,132, "living diblock copolymers", which
have been produced in a cértain way, i.e. by polymerizing first s~yrene and
then the diene, can be converted by reaction with divinyl benzene into poly-
segment polymers of the form SX-By~Cz~By~S (C = polymerized radical of the
divinyl benzene). It is rather difficult to carry out this process because
insoluble gels are readily formed by cross-linking.
The present invention also provides a polysegment co-polymer con-
sisting of coupled diblock co-polymers produced by coupling diblock
co-polymers of styrene which is unsubstituted or substituted at the nucleus
by halogen or vinyl benzene and unsubstituted or substituted at the side
chain by a lower alkyl radical, and a conjugated diene of the idealized
form SX-By wherein the styrene block S has 10 - 5000 structural units x and
the diene block B has 190 - 19 000 structural units y with 0.5 - 20 mMol
of sulphur chlorides per 100 g of diblock co-polymer.
Whereas the known process for the production of
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polysegment copolymers can only be carried out with "living
~o]ymers", any deactivated diblock copolymers may be used
in the process according to the invention. The known process
requires an ad~itional diiunctional monomer (divinyl benzene)
which is incorporated as an additional block in the polyblock
copolymers. No such additional block is formed in the
process according to the invention. Accordingly, the products
obtained are not only chemically different but they also
dif~er in their phrsical properties.
The diblock copolymers used as the starting material
for the process according to the invention may be obtained
in known manner by anionic, cationic or radical polymerisation.
In the case of anionic polymerisation, for example
on lithium alkyl catalysts, styrene and the conjugated diene,
preferably butadiene, may be simultaneously subjected to
polymerisation. Alternatively~ it is possible to polymerise
flrst the styrene and then the diene~ or first the diene
and then the styrene.
~Suitable con~ugated dienes are~ in particular~
acyclic dienes containing from 4 to 8 carbon atoms~ for
example butadiene~ isoprene and piperylene. Butadiene and
i~oprene are preferably used.
In the context of the invention, styrene and
structural units derived from styrene also include nucleus-
substituted styrenes (ior example vinyl toluene or chloro-
styrene) and ~tyrene~ alkylated in the side chain~ ior example
a-methyl styrene.
~ he production oi diblock copolymers by anionic
polymerisation is known. Polymerisation is preferably carrled
out ln hydrocarbons a~ solvents, whilst lithium compounds,
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for example lithium alkyls, are generally used as catalysts. One
of the two monomers may be polymerised first and the second added
on completion of polymerisation. However, it is also possible to
introduce both monomers simultaneously. In this case, the diene
polymerises ~irst and ~orms a polydiene block which only contains
small quantities of styrene. After the diene has been used up the
styrene polymerises and ~orms a polystyrene block which contains
practically no diene. The steric structure of the polydiene block
may be influenced by cocatalysts, such as for example ethers or
amines.
This procedure results initially in the iormation
of a living polymer which is deactivated by the addition of
~roton-active agents, such as water, ethyl alcohol, acids or
amines. The diblock copolymer thus obtained may be isolated
and sub~equently æubjected to the process according to the
invention. Alternatively, the deactivated solution obtained
may be directly treated with the sulphur chlorides. It i9
; also possible not to deactivate the dib]ock polymer and
insteaA to treat the reaction solution directly with the
sulphur chloricles. In thi~ case~ at least the same molar
quantity of fiulphur ohlorlde, based on the lithium, iB used.
Disulphur dichloride i8 preferably used as the sulphur
chloride
The dlblock polymers used pre~erably contaln
styrene and/or a-methyl styrene as the hard component with
a glass transition temperature above 10C. The soft
component (glass transition temperature below 0C) ie
preferably iormed by diene rubbers, such as butadiene or
lsoprene. The diene component is predominantly present in
~0 the iorm of 1,4-bonds. However, it may also contain ~ I
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up to 8Q% of 1,2-bonds.
The molecular weight of the styrene block may be between 1000
and 500,000, preferably between 5000 and 100,000 whilst the molecular weight
of the rubber block should be between 10,000 and 1,000,000 and preferably
between 20,000 and 500,000.
The reaction of sulphur chlorides with diene polymers is known.
It is used to improve "cold flow", especially in the production of cis-l,
4-polybutadiene, the other properties of the rubber remaining unaffected.
(British patent 1,118,615 issued July 3, 1968 to Nutzel et al assigned to
the applicant herein.) Surprisingly, it has now been found that the
reaction of diblOckco-polymer5 of styrene and butadiene, which have hardly
any technological value, with sulphur chlorides results in the formation
of polymers which can be processed by processes of the kind normally used
for thermoplasts and which at the same time show elastomeric properties.
The products obtained in accordance with the invention are thermoplastic
and may be processed in the absence of additives in injection-moulding
machines, extruders or the like. At room temperature they show typical
rubber properties, i.e. a high modulus, high elongation, hardness and
elasticity. Whereas triblock co-polymersof dienes and styrene have the
serious disadvantage of undergoing a drastic deterioration in hardness,
elasticity and moduli at elevated temperature, these values are reduced to
a very much lesser extent in the polymers produced in accordance with the
invention.
The products obtained by coupling with the sulphur chlorides are
characteristerised by predominant bonding of-the diene components of two or
more diblock molecules of the structure S -By. Triblocks S -Bz-S are :~
formed in
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the first stage, their middle block Bz being formed from the two
blocks By o~ the starting components by bonding through sulphur
bridges. Bz is branched with a high degree of probability.
The cross-linking does not stop after the reaction between
two molecules. As can be shown by gel permeation chromatography,
a very wide distribution spectrum is formed. In the accompanying
drawing (a gel permeation chromatogram), the abscissa represents
the elution volume and the ordinate represents the relative con-
centration. I = dib~ock butadiene/styrene, II = I coupled with
disulphur dichloride). This wide distribution is responsible for
the excellent processing properties of the products obtained.
It is sur~rising that the products obtained
show excellent solubilities in h~d rocarbon solvents. They
are soluble even in chloroform and9 in some cases, even in
ethyl acetate,
The high solubility, even of extremely high molecular
weight fractions, in aromatic solvents and chloroform,
indicates a more spherical structure of the molecules. ~his
ls also indicated by the low vis008ity number of the products.
I'his structure distinguishes the polymers produced in
accordance with the invention both from triblock copolymer 9
of the type SBS a3 well as from polymers produced by reacting
living diblock copolymers with divinyl benzene.
Solvents suitable for use in the proces~ according
to the invention include any solvent in which the diblock
copolymers are soluble. It is preferred to use the solvents
in which the diblock polymers are formed, for example aliphatic
hydrocarbons, cyclic hydrocarbons, aromatic solvents or mixturec
thereof with ethers or cyclic ethers~ If the diblock polymers
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have been isolated in the form of solids by any given proces~,
it is also possible to use other solvents for the coupling
reaction providing they do not react with or result in the
decomposition of the sulphur chlorides~
The sulphur chlorides are preferably added in the
form of A solution in the same solvent as that of the diblock.
They may also be added in un~iluted form as liquids.
The re~ction temperatures may be in the range Or
irom -20 to ~150C, although the reaction is preferably
carried out at room temperature The reaction time ranges
from 5 to 120 minutes9 preferably from 15 to 60 minutes~
depending upon the reaction temperature.
The quantity in which the crosslinking agent i8
used depends on the required degree o~ cross-linking. The
crosslinking agent may be used,for example, in quantities of
from 0.5 to 20 m~lol and preferably in quantities of from 3 to
6 mMol per 100 g o~ rubber.
The process may also be carried out in the absence
of ~olvents, In this case~ the ~ulphur chloride~ are elther
previouely added in solution to the diblock copolymer and the
mixture subsequently isolated by the usual methods~ or they
are added in concentrated form or in the form of a concentrated
solution in a mixer. Suitable mixers are~ for example~ two-
roll or multi-roll stands~ internal mlxers or screw extruder~3.
The process may be carried out either oontinuously
or in batches. In lts continuous i~orm, the reaction may
be carrled out in reactor cascadea or in tube reactora.
The polymer i9 recovered from its solution either
by precipitation with an organic non-~olvent or by coagulation
3o with hot water. A ~tabiliser may be added to the polymer
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before this stage.
The products obtained in accordance with the invention are
suitable for the production of shoe soles, hoses and industrial
rubber articles.
The polymers may be processed in the absence of additives~
although it is also possible to add conventional rubber additives,
such as carbon black, light fillers, dyes, pigments or processing
oils.
In the following examples the percentages are by weight.
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Example 1
22.4 litres of dry toluene are initially introduced
into a 60 litre vessel in the absence of air and moisture.
3.12 kg of dry styrene are added and polymerisation is
initiate~ by the addition of 31.2 mol of 2M n-butyl lithium.
The t~m~erature is kept between 30 and 50C. After 3 hours,
3.12 kg of butadiene are added and the mixture is left to
~olymerise for 15 hours at the eame temperature. 0.40,h of
S2C12 (based on the rubber) dissolved in toluene i9 then
added, and the mixture is left to react for 30 minutes at
room temperature. The solution is then stabilised by the
addition of 0.5B of di-tert-butyl methyl phenol and the
rubber is isolated by precipitation with methanol. An
almost co]ourless product i8 obtained after drying at 70C
in a vacuum drying cabinet. Sheets produced from this
product by pressing for 10 minutes at 170C were tested ln
comparison with a ~tandard co~mercial-grade thermopla~tic
rubber (trade name ~ariflex TR 4122~.
Produced in Standard
accordance with commercial
Example 1 product
F ~trength (MPa) 6.6 7.2
D elongation (/0) 530 970
M modulus 300 (MPa) 4.1 1.6
M modulus 500 (MPR) 6. 5 2.6
H hardnes~ 20/70a (Shore A) 94/91 71/45
H hardness 100/120/150 42/17/4 7/1/-
E elastlclty 20/70 46/39 38/30
Str. structure aocordln~ 94 97
to Pohle (N)
It can be seen that the product according to the
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invention is superior to the stanAard commercial product in
numerous aspects, but especially in the modulus values. In
addition, the product shows greater hardness, coupled with
higher elasticity, than the standard co~mercial product. The
dependence upon temperature of hardness is of particular
significance. The product according to the invention shows
a considerably lower reduction in hardness with increasing
temperature. It also shows advantages during extrusion.
Whereas the profile obtained with the standard commercial-
grade product was slightly rough and showed signs of injection
swelling, the product according to the invention showed a
smooth profile without any in;ection swelling.
Example 2
1.1 litres of dry toluene were introduced into a
2 litre autoolave in the absence of air and moisture. 192 g
of dry butadiene are added and polymerisation is initiated by
the addition of 1.3 ml o~ 2 M sec-butyl lithium. The temperature
is kept at 40 to 60C. After 3 hours, 127 g of styrene are
added, and the mixture is left to polymerise for another 3 hours.
The llving polymer is deactivated by the addition of
0.32 g of 2~6-di-tert-butyl-4-methyl phenol in toluene.
0.4G/o of S2C12 is then added, based on solid rubber~ and
the mixture ls left reacting ior 60 minutes~ Aiter isolatlon
by coagulation with steam, the product i9 drled at 70C
in a vacuum drying cabinet. Sheets pressed ~rom the polymer
(10 minutes~ 170C) show the following properties:
F 6.9 MPa~ D 4755~ M 300 /0 4.2 MPa, H (23~ 70, 100,
120~ 150) 83, 70~ 52, 30~ 12; E 23/70 47/38~ Str 100~
, abrasion (40/60 emery) 135/68 mm3. T~e standard commercial
3 A comparison material (Cariflex TR 4122~ showed the iollowing
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values: ~ 6.~ MPa, 1) 99S', M (300%) 3.5 MPa, H(23, 70,
100, 1~(), ]50) 76, 51, 6, 1, 0; ~(23/70) 40/41, Str. 88,
a~ra~sion (40/~ emery) 277/170.
I~`xamT)l e
].1 litres of dry toluene are introduced into a
2 ~itre autoclave in the absence o~ air and moisture. 91 g
of drv styrene are added and the polymerisation reaction is
initiated by the addition of 3.6 ml of 2 M n-butyl lithium.
~fter 3 hours at 30-40C, dry isoprene (260 g) is added and
11o]ymeri~ation continued at 40 to 60C. After 3 hours,
o.5~b of 2,h-di-tert-butyl-4-methyl phenol (based on rubber)
is added and the product is precipitated with methanol
(~) = 0.72 dl/g. After drying, the polymer is dissolved
in toluene and freed from traces of moisture by introducing
nitrogen at 70C. After cooling to room temperature~ 1.0
of disulphur dichloride ~based on rubber) is added~ followed
by stirring for 60 minutes. The product is isolated in the
same way as described above, an elastic, somewhat tacky
polymer being obtained. It ha~ an (~)-value of 1.59 dl/g.
Exam~le 4
A somewhat tacky polymer is obtained ln the same
way as de~cribed ln Example 3, except that a mlxture of
195 g of butadiene and 65 g of isoprene ls used. Before
treatment wlth 1 phr of S2C12~ the polymer has an (~)-value
$ 0.61. After the reaction, it~ value i3 0.~7.
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