Initiator systems containing vanadium tetrachloride for the (co)polymerization of isoolefins

This invention relates to an initiator system for the polymerization of isoolefins having 4 to 16 carbon atoms, optionally with monomers polymerizable with isoolefins, the system consisting of or one or more aromatic or heteroaromatic, polycyclic hydrocarbons and an aged, organic solution of vanadium tetrachloride, wherein the concentration of the vanadium tetrachloride is 0.01 mmol to 500 mmol per liter of solvent and the molar ratio of aged vanadium tetrachloride to polycyclic hydrocarbons is in the range from 100:1 to 1:100. It is possible by means of the initiator system according to the invention to produce polyisoolefins, in particular butyl rubbers, at relatively high temperatures with only a low gel content and of a sufficiently high molecular weight.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention provides a novel initiator system containing vanadium 
for the (co)polymerisation of isoolefins, a process for the production of 
the novel initiator system and the use thereof for the production of 
polymers from isoolefins optionally with monomers copolymerisable with 
isoolefins, in particular for the production of butyl rubbers. 
2. Description of the Prior Art 
The process currently used to produce butyl rubber is known, for example, 
from Ullmanns Encyclopedia of Industrial Chemistry, volume A 23, 1993. In 
the slurry process, isobutene is cationically copolymerised with isoprene 
with methyl chloride as the process solvent using aluminium chloride as 
the initiator with the addition of small quantities of water or hydrogen 
chloride. It is also known to initiate this copolymerisation using a 
combination of tertiary halides combined with Lewis acids (Kennedy, 
Marechal, Carbocationic Polymerisation, Wiley 1982). A feature common to 
both processes is that polymerisation temperatures of approximately 
-100.degree. C. are necessary in order to achieve a molecular weight which 
is sufficiently high for use in the rubber-processing industry, which 
entails very costly cooling of the reaction. In these processes, as a 
general rule molecular weights become ever lower as temperature increases. 
It is also known to copolymerise isobutene with various comonomers at 
temperatures of approximately -40.degree. C. using vanadium tetrachloride 
as the initiator, either in pure form or as a solution in heptane, with 
optional activation by light or the addition of aromatic compounds 
(Miroslav Marek et al., J. Polym. Sci. Polym. Chem. Ed. 16, 2759-2770 
(1978); J. Pilar, L. Toman, M. Marek, J. Polym. Sci. Polym. Chem. Ed. 14, 
2399-2405 (1976); L. Toman, M. Marek, Makromol. Chem. 177, 3325-3343 
(1976); M. Marek et al., U.S. Pat. No. 3,997,417; L. Toman, M. Marek, J. 
Macromol. Sci.-Chem., A15(8), 1533-1543 (1981); M. Marek, J. Polym. Sci. 
Symp. 56, 149-158 (1976)). While the copolymers produced using this 
process do indeed have a rubbery consistency, they are insoluble due to 
their elevated gel content and precipitate during polymerisation in an 
alkane solution or in bulk, so causing serious problems for the industrial 
performance of this reaction. 
The homopolymerisation of isobutene with vanadium tetrachloride as the 
initiator and ammonia (L. Toman, M. Marek, Polymer Bull. 6, 570-576 
(1982)) as the co-initiator is described in bulk and in solution (solvent: 
heptane). Polymerisation was performed in the temperature range from 
-10.degree. C. to -75.degree. C. in darkness. Polymerisation does not 
proceed in this process without the presence of ammonia. Yields are 
dependent upon the molar ratio of vanadium tetrachloride to ammonia and 
reach a maximum at a ratio of 1:1. The molecular weights achieved are 
independent of this ratio and rise with increasing monomer concentration. 
A molecular weight (determined viscosimetrically) of 2015 kg/mol was 
achieved in bulk polymerisation at -75.degree. C. In heptane at a monomer 
concentration of 4.65 mol/l, the value was only half so high. The 
molecular weights achieved decrease as temperature rises. Other polymer 
characteristics, in particular the gel content, are not stated. 
The polymerisation of olefinic hydrocarbons with vanadium tetrachloride in 
combination with the most varied aromatic compounds as coinitiators in the 
temperature range from -110.degree. C. to +110.degree. C. is known from 
U.S. Pat. No. 3,326,879. A disadvantage of the processes described in the 
stated US patent is that some of the listed coinitiators, if used in a 
quantity of greater than 100 mol. %, inhibit polymerisation and, as our 
own tests have shown, the only copolymers of isobutene with isoprene which 
are obtained are those having an elevated gel content. This also applies 
to the process described in U.S. Pat. No. 3,997,417 for the polymerisation 
and copolymerisation of monomers with olefinic double bonds in the 
presence of polyvalent metal halides, for example vanadium tetrachloride, 
in the presence of light in the temperature range from -140.degree. C. to 
+30.degree. C. Thus, according to Example 12, copolymers of isobutylene 
and isoprene are obtained which have a gel content of 15% and, according 
to Example 11, copolymers of isobutylene and butadiene which have a gel 
content of 10%. Depending upon the reaction conditions, molecular weights 
are between 75 and 550 kg/mol. The polymerisation process described in 
U.S. Pat. No. 3,998,713 using tetravalent metal halides in combination 
with alkaline earth or alkali metals or the hydrides or amalgams thereof 
as co-initiators with irradiation in the temperature range from 0.degree. 
C. to -140.degree. C. is also unsuitable for polymerising or 
copolymerising monoolefinic and diolefinic compounds. Here too, an 
elevated gel content is obtained on polymerisation. Even at low 
temperatures, the molecular weights of the polymers are unsatisfactory. 
The same also applies to the polymerisation and copolymerisation of 
monomers having olefinic double bonds in the presence of, for example, 
halides of tetravalent vanadium with or without light described in DE 2 
125 800 and DE 2 119 305. The achieved molecular weights of the polymers 
are unsatisfactory and the gel content of the polymers, for example when 
butyl rubbers are produced, is too high. 
It has now surprisingly been found that the above-stated disadvantages 
during the (co)polymerisation of isoolefins can be avoided if isoolefins 
are copolymerised in the presence of the initiator system containing 
vanadium described below. 
SUMMARY OF THE INVENTION 
The present invention accordingly provides an initiator system for the 
polymerisation of isoolefins having 4 to 16 carbon atoms, optionally with 
monomers copolymerisable with isoolefins, the system consisting of one or 
more aromatic or heteroaromatic, polycyclic hydrocarbons (coinitiator) and 
an aged, organic solution of vanadium tetrachloride (initiator), wherein 
the concentration of the vanadium tetrachloride is 0.01 mmol to 500 mmol 
per liter of solvent and the molar ratio of aged vanadium tetrachloride to 
polycyclic hydrocarbons is in the range from 100:1 to 1:100.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Aromatic or heteroaromatic, polycyclic (at least bicyclic) hydrocarbons are 
used alone or in combination with each other as coinitiators in the 
initiator system according to the invention. The aromatic or 
heteroaromatic polycyclic hydrocarbons may optionally be substituted with 
alkyl or alkylene groups. Further possible substituents are halogen, cyano 
groups, nitro groups, alkoxy groups and substituted phenyl groups. Bi-, 
tri- and tetracyclic aromatic or heteroaromatic hydrocarbons are 
preferably used. Examples of suitable coinitiators are, for example, 
naphthalene, anthracene, indene, coumarone, carbazole, N-vinylcarbazole, 
biphenyl, p-terphenyl, acenaphthene, acenaphthylene, fluoranthene, 
fluorene, phenanthrene, pyrene, together with octylated diphenylamine 
(Vulkanox OCD from Bayer). 
The conditions for ageing the initiator are dependent upon the solvent 
used. Suitable solvents for ageing the initiator for the purposes of the 
invention are hydrocarbons, in particular aliphatic and/or aromatic 
hydrocarbons without functional substituents and having 4 to 20 carbon 
atoms and a boiling point of above -20.degree. C. Preferred solvents are 
those having a boiling point of above +20.degree. C. and a melting point 
of below 20.degree. C., with those solvents having a melting point of 
below 0.degree. C. being particularly preferred. These solvents may be 
used alone or combined with each other. Examples of such hydrocarbons are: 
pentane, hexane, 2,3-dimethyl-butane, heptane, cyclopentane, cyclohexane 
and/or methylcyclohexane, with pentane and/or hexane being particularly 
preferred. 
Ageing of the initiator may, in principle, be performed over a broad 
temperature range, essentially limited only by the melting point and the 
boiling point of the solvent used. A preferred temperature range is from 0 
to 40.degree. C., with +10 to +30.degree. C. being particularly preferred. 
Ageing may be performed in the presence of light or in darkness. Ageing is 
preferably performed in daylight or under artificial light (in the visible 
or ultraviolet range). 
Optimum ageing time is dependent upon the solvent used, the temperature, 
the quantity of light and the concentration of the solution. Ageing times 
of a few minutes to several weeks are possible, with ageing times of a few 
hours to a few days being preferred and ageing times of one hour to 24 
hours, in particular of 24 hours, being particularly preferred. 
Ageing of the vanadium tetrachloride in the appropriate organic solvent may 
be performed in the absence or presence of the coinitiators. In a 
preferred embodiment, ageing proceeds in the absence of the coinitiators. 
The present invention accordingly also provides a process for the 
production of the initiator system described above, which process is 
characterised in that the vanadium tetrachloride is dissolved in one of 
the organic solvents described above and the resultant solution is 
subjected to an ageing process in the presence of light or in the absence 
of light, wherein the concentration of the vanadium tetrachloride is 0.01 
mmol to 500 mmol per liter of solvent. 
The present invention moreover provides the use of the initiator system for 
the production of polyisoolefins by polymerising isoolefins having 4 to 16 
carbon atoms, optionally with conjugated diolefins having 4 to 6 carbon 
atoms and/or cationically polymerisable mono- or polyunsaturated compounds 
having 4 to 16 carbon atoms, at temperatures of -100.degree. C. to 
+20.degree. C., preferably from -60.degree. C. to 0.degree. C., in 
particular from -45.degree. C. to -15.degree. C., and pressures from 0.001 
to 70 bar, preferably from 0.1 to 2 bar. 
In order to remove contaminants, in particular moisture, during 
polymerisation, alkali and alkaline earth metals, the amalgams thereof 
with mercury or hydrogen compounds of the metals of groups I, II, III and 
IV of the periodic system may be added to the monomer mixture as 
desiccants. In this manner, the required quantity of catalyst may be 
reduced. 
The concentration of the aged vanadium tetrachloride is preferably 0.01 
mmol to 500 mmol per liter of solvent. The molar ratio of aged vanadium 
tetrachloride to the above-mentioned polycyclic hydrocarbons is preferably 
in the range from 10:1 to 1:10. 
Isoolefins having 4 to 16 carbon atoms, preferably 4 to 8 carbon atoms, 
which may be mentioned by way of example are: isobutene, 
2-methyl-1-butene, 3-methyl-1-butene, 4-methyl-1-pentene and 
.beta.-pinene, preferably isobutene and 2-methyl-1-butene; conjugated 
diolefins having 4 to 6 carbon atoms which may be mentioned are: isoprene, 
butadiene, 2,3-dimethylbutadiene, cyclopentadiene, methylcyclopentadiene, 
1,3-cyclohexadiene, preferably isoprene and cationically polymerisable, 
mono- or polyunsaturated organic compounds having 4 to 16 carbon atoms, 
preferably 4 to 10 carbon atoms which may be mentioned are: styrene, 
4-methylstyrene, divinylbenzene, .alpha.-methylstyrene, dimethylfulvene, 
preferably 4-methylstyrene and divinylbenzene. 
In the event that the process according to the invention is to be used for 
copolymerising the stated isoolefins with the stated conjugated diolefins 
and/or the cationically polymerisable, mono- or polyunsaturated organic 
compounds, a weight ratio of isoolefins to diolefins and unsaturated 
organic compounds of 95:5 to 99.5:0.5 is preferred. 
Polymerisation may, in principle, be performed at various pressures. 
Pressures both above and below atmospheric are permissible. Pressure is 
preferably adjusted in such a manner that the reaction mixture boils at 
the desired reaction temperature so that the heat of reaction arising 
during polymerisation may be dissipated by boiling cooling. The ideal 
pressure is determined by the boiling points and quantity of the solvents 
used, the boiling points of the monomers used and the desired reaction 
temperature. 
If, for example, polymerisation is performed without solvent (bulk 
polymerisation), the ideal pressure is calculated using the following 
formula: 
##EQU1## 
In this formula, T denotes the reaction temperature in Kelvin and p the 
pressure in mbar. 
In specific cases, the pressure actually used may deviate from this ideal 
value by up to 100 mbar not only to greater but also to lesser values. 
Deviations of &lt;50 mbar are preferred, with deviations of &lt;20 mbar being 
particularly preferred. 
Polymerisation may be performed both continuously and batch-wise. 
In a preferred embodiment, polymerisation is performed batch-wise, for 
example in the following manner: 
The reactor, which has been precooled to the reaction temperature, is 
charged with the solvent, the coinitiator and the monomers. The initiator 
is then pumped in at a rate of 1 ml/hour to 1000 ml/hour until an 
exothermic reaction starts. All operations are performed under protective 
gas or a slight vacuum. The course of the reaction is monitored by means 
of the evolution of heat. Once the exothermic reaction has come to an end, 
it is terminated with a phenolic antioxidant, such as for example 
2,6-di-tert.-butyl-4-methylphenol, dissolved in ethanol. 
It is of great significance to the polymerisation according to the 
invention that the aged vanadium tetrachloride hydrocarbon solutions 
(initiator) are used in combination with the stated coinitiators. 
Suitable polymerisation solvents for the purposes of the invention are 
aliphatic and/or aromatic (optionally halogenated) hydrocarbons without 
functional substituents. Preferred solvents are those having a melting 
point of below 20.degree. C. Particularly preferred solvents are those 
having a melting point of below 0.degree. C. Examples of suitable 
aliphatic solvents are: methyl chloride, methylene chloride, chloroform, 
carbon tetrachloride, propane, butane, pentane, hexane, 
2,3-dimethylbutane, heptane, cyclohexane, methylcyclohexane, chloroethane, 
1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 
1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 
1-chloropropane, 2-chloropropane, 1,2-dichloropropane, 
1,2,3-trichloropropane, 1-chlorobutane, 2-chlorobutane, 
1,4-dichlorobutane, 1-chloro-2-methylpropane, 1-chloropentane, 
2,4-dimethylpentane, 2,2,4-trimethylpentane, dodecane, 1-chlorododecane, 
petroleum ether, chlorocyclohexane, cyclododecane and/or decalin. Examples 
of aromatic solvents are: benzene, toluene, chlorobenzene, 
1,2-dichlorobenzene, ethylbenzene, xylene, 1,2,3-trimethylbenzene, 
1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, diethylbenzene, 
1,2,3,4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene, 
1,2,4,5-tetramethylbenzene, pentamethylbenzene, 
1-isopropyl-4-methylbenzene, 1,3-diisopropylbenzene, 
1,4-diisopropylbenzene, 1-tert.-butyl-3,5-dimethylbenzene and/or 
1,3,5-triisopropylbenzene. 
It is particularly surprising that it is possible by using the initiator 
system according to the invention consisting of an aged organic solution 
of vanadium tetrachloride (initiator) in combination with one or more 
aromatic or heteroaromatic polycyclic hydrocarbons (coinitiator) to 
produce polyisoolefins, in particular butyl rubbers, at relatively high 
temperatures (-40.degree. C.) having only a low gel content and a 
sufficiently high molecular weight, although it would have been expected 
according to the prior art, that, when using vanadium tetrachloride as the 
initiator, the polymerisation of isoolefins is associated with a 
relatively high gel content, often combined with a molecular weight which 
is insufficiently high for rubber applications. 
EXAMPLES 
Experimental Details 
Gel contents were determined in toluene after a dissolution time of 24 
hours at 30.degree. C. with a sample concentration of 12.5 g/l. Insoluble 
fractions were separated by ultracentrifugation (1 hour at 20000 
revolutions/minute and 25.degree. C.). 
The solution viscosity .eta. of the soluble fractions was determined in 
toluene at 30.degree. C. by Ubbelohde capillary viscosimetry. 
Molecular weight Mv calculated from solution viscosity was determined using 
the following formula: ln(Mv)=12.48+1.565*ln.eta.. 
GPC. investigations with GPC-viscosimetry coupling were performed in a 
instrument equipped with eight Styragel columns of sizes 100, 1000 
(2.times.), 10.sup.4 (2.times.), 10.sup.5 (2.times.) and 10.sup.6 nm. 
Total column length is 976 cm. The eluent, THF, was pumped at 0.5 ml/min. 
1.93 ml fractions were measured online in an Ubbelohde viscosimeter. 
M.sub.v values were calculated with the constants K=5.times.10.sup.-4 dl/g 
and .alpha.=0.6. Evaluation was performed by universal Benoit calibration 
using PC software from Kirschbaum & Schroeder GmbH. 
Mooney viscosities were measured after 8 minutes at a temperature of 
125.degree. C. 
UV spectra of the catalyst solutions were measured using a Perkin-Elmer UV 
spectrometer at room temperature with an undiluted catalyst solution in a 
cuvette with a pathlength of 0.01 mm. 
Unless otherwise stated, the solvents used were purified before use by 
distillation over calcium hydride under an argon atmosphere. 
The isobutene used in the polymerisations was dried by being passed through 
a column packed with sodium on aluminium oxide. 
The isoprene used was filtered through a column with dried aluminium oxide 
in order to remove the stabiliser and used in this form for the 
polymerisation. 
The other comonomers used were purified before use by distillation over 
calcium hydride under an argon atmosphere. 
Synthesis of Initiator (ageing of VCl.sub.4) 
Example 1 
500 ml of hexane were introduced into a vessel under argon. 24.1 g (0.125 
mol) of vanadium tetrachloride were added. The solution was exposed to 
daylight with gentle stirring for 7 days, wherein the red coloration 
became distinctly deeper and the occurrence of small quantities of a solid 
was observed. The extent of this color change may be seen by comparing the 
UV spectra, which are shown together in the Figure. 
The precipitated solid (&lt;&lt;1%) was filtered out under argon. The remaining 
solution was stored under argon and used in this form to initiate 
polymerisation. 
If correctly stored, this solution may be used for several weeks. Any 
slight turbidity occurring during storage may be removed by filtration. 
Example 2 
As Example 1, the ageing time being 2 h in this case. 
Example 3 
100 ml of 2,3-dimethylbutane were introduced into a vessel under argon. 
4.8188 g (0.025 mol) of vanadium tetrachloride were added. The solution 
was exposed to daylight with gentle stirring for 9 days, wherein the brown 
coloration became distinctly deeper and the occurrence of small quantities 
of a solid was observed. The precipitated solid was filtered out under 
argon. The remaining solution was used in this form to initiate 
polymerisation. 
Example 4 
500 ml of toluene dried by distilling off LiAlH.sub.4 are combined at room 
temperature with 125 mmol of VCl.sub.4 and stirred for 2 hours. The 
resultant slurry becomes deep black. The precipitate is filtered out. 
Example 5 
50 ml of methylcyclohexane dried by distilling off CaH.sub.2 are combined 
at room temperature with 12.5 mmol VCl.sub.4 and stirred for 24 hours. The 
clear solution is deep red and is used for polymerisation without being 
filtered. 
Example 6 
100 ml of heptane dried by distilling off CaH.sub.2 are combined under 
argon with 25 mmol of VCl.sub.4 and stirred for 24 hours. A deep red, 
clear solution was produced. 
Polymerisations 
Example 7 
500 g of isobutene and 11.918 g (1.96 mol. %) of isoprene were introduced 
into a vessel under argon with exclusion of light at a temperature of 
-40.degree. C. 0.036 g of anthracene and 1.6 ml of initiator solution from 
Example 1 were added. After a reaction period of 15 minutes, the 
exothermic reaction was terminated due to the increasing viscosity by 
adding a precooled solution of 1 g of 
2,2'-methylene-bis(4-methyl-6-tert.-butylphenol) (Vulkanox BKF from Bayer 
AG, Leverkusen) in 250 ml of ethanol. Once the liquid had been decanted, 
the precipitated polymer was washed with 2.5 1 of methanol, rolled out to 
a thin sheet and dried for 1 day under a vacuum at 50.degree. C. (Yield: 
91.3 g=17.8%). 
The resultant slightly brown polymer had a Mooney value of 55, a gel 
content of 3.1% and an intrinsic viscosity of 1.0632 dl/g. 
Example 8 (Comparative Example) 
600 g of isobutene and 13.63 g (200 mmol) of isoprene were introduced into 
a vessel under argon at a temperature of -40.degree. C. 4 ml of initiator 
solution from Example 2 were added in the presence of light. After a 
reaction period of 15 minutes, the exothermic reaction was terminated due 
to the increasing viscosity by adding a precooled solution of 1 g of 
2,2'-methylene-bis(4-methyl-6-tert.-butyl-phenol) (Vulkanox BKF from Bayer 
AG, Leverkusen) in 250 ml of ethanol. Once the liquid had been decanted, 
the precipitated polymer was washed with 2.5 1 of methanol, rolled out to 
a thin sheet and dried for 1 day under a vacuum at 50.degree. C. (Yield: 
92.6 g=15%). 
The resultant slightly brown polymer had a Mooney value of 98, a gel 
content of 43%. The intrinsic viscosity of the soluble fractions was 1.55 
dl/g. 
Example 9 
The polymerisation from Example 7 was repeated, with the difference that, 
instead of the initiator from Example 1, the initiator solution from 
Example 3 was used. Yield: 110 g=21.5%. 
The resultant polymer had a Mooney value of 60.5, a gel content of 3.5% and 
an intrinsic viscosity of 1.359 dl/g. 
Example 10 (Comparative Example) 
The polymerisation from Example 7 was repeated, with the difference that, 
instead of the initiator from Example 1, the equimolar quantity of 
vanadium tetrachloride dissolved in hexane was used. Yield: 124 g=24%. 
The resultant polymer had a Mooney value of 65, a gel content of 23.3% and 
an intrinsic viscosity of 0.64 dl/g. 
Example 11 
598 g of isobutene and 13.63 g (200 mmol) of isoprene were introduced into 
a vessel under argon at a temperature of -40.degree. C. 8 ml of initiator 
solution, produced in the same manner as in Example 1 with an ageing time 
of 96 h, were added in the presence of light. After a reaction period of 
20 minutes, the exothermic reaction was terminated due to the increasing 
viscosity by adding a precooled solution of 1 g of 
2,2'-methylene-bis(4-methyl-6-tert.-butylphenol) (Vulkanox BKF from Bayer 
AG, Leverkusen) in 250 ml of ethanol. Once the liquid had been decanted, 
the precipitated polymer was washed with 2.5 1 of methanol, rolled out to 
a thin sheet and dried for 1 day under a vacuum at 50.degree. C. (Yield: 
74.2 g=12.1%). 
The resultant slightly brown polymer had a Mooney value (125.degree. C., 
1+8') of 30 and a gel content of 43%. The intrinsic viscosity of the 
soluble fractions was 0.6 dl/g. 
Example 12 
600 g of isobutene and 13.63 g (200 mmol) of isoprene were introduced into 
a vessel under argon at a temperature of -40.degree. C. 10 ml of initiator 
solution, produced in the same manner as in Example 6 with an ageing time 
of 168 h, were added with the exclusion of light. After a reaction period 
of 17 minutes, the exothermic reaction was terminated due to the 
increasing viscosity by adding a precooled solution of 1 g of 
2,2'-methylene-bis(4-methyl-6-tert.-butylphenol) (Vulkanox BKF from Bayer 
AG, Leverkusen) in 250 ml of ethanol. Once the liquid had been decanted, 
the precipitated polymer was washed with 2.5 1 of methanol; rolled out to 
a thin sheet and dried for 1 day under a vacuum at 50.degree. C. (Yield: 
61.4 g=10%). 
The resultant slightly brown polymer had a Mooney value (125.degree. C., 
1+8') of 94 and a gel content of 37%. The intrinsic viscosity of the 
soluble fractions was 1.64 dl/g. 
Example 13 
600 g of isobutene and 13.63 g (200 mmol) of isoprene were introduced into 
a vessel under argon at a temperature of -40.degree. C. 8 ml of initiator 
solution, produced in the same manner as in Example 4 with an ageing time 
of 2 h, were added in the presence of light. After a reaction period of 15 
minutes, the exothermic reaction was terminated due to the increasing 
viscosity by adding a precooled solution of 1 g of 
2,2'-methylene-bis(4-methyl-6-tert.-butylphenol) (Vulkanox BKF from Bayer 
AG, Leverkusen) in 250 ml of ethanol. Once the liquid had been decanted, 
the precipitated polymer was washed with 2.5 1 of methanol, rolled out to 
a thin sheet and dried for 1 day under a vacuum at 50.degree. C. (Yield: 
76.7 g=12.5%). 
The resultant slightly brown polymer had a Mooney value (125.degree. C., 
1+8') of 77 and a gel content of 49%. The intrinsic viscosity of the 
soluble fractions was 1.36 dl/g. 
Example 14 
As Example 13; polymerisation was performed in the absence of light. Yield 
was: 59.6 g=9.7%. 
The resultant slightly brown polymer had a Mooney value (125.degree. C., 
1+8') of 67.5 and a gel content of 59%. The intrinsic viscosity of the 
soluble fractions was 1.0 dl/g. 
Example 15 
1000 ml of n-hexane, 200 g of isobutene and 75 mmol of isoprene were 
introduced into a vessel under argon at -40.degree. C. and combined with 
20 ml of initiator solution from Example 5. Conversion of 52% was achieved 
after 120 minutes stirring at -40.degree. C. The product had a gel content 
of 30%, the intrinsic viscosity of the soluble fractions was 0.37 dl/g. 
The polymer was of a tacky consistency. M.sub.w =400 kg/mol and M.sub.n =8 
kg/mol were determined by gel permeation chromatography. The long chain 
branched polymer fraction was determined at 5%. 
Example 16 (Effect of different ageing times) 
In order to demonstrate the effect of different initiator ageing times on 
the outcome of the polymerisations, the polymerisation from Example 9 was 
repeated, wherein the initiator used from Example 3 was aged for different 
periods. The results are summarised in the following table. 
______________________________________ 
Ageing period 
(days) Yield (%) Mooney value 
Gel content (%) 
______________________________________ 
3 17 82 31.4 
9 21.5 60.5 3.5 
14 0 (no reaction!) 
-- -- 
______________________________________ 
Example 17 (Polymer tests) 
500 g of polymer were produced in accordance with the instructions of 
Example 7. The material had a Mooney value of 51, a gel content of 2.1%, 
an M.sub.n of 31.8 kg/mol, an M.sub.w of 8590.7 kg/mol and an isoprene 
content of 2.2 mol. %. 
A rubber compound was produced from this polymer on a laboratory mill in 
accordance with the following formulation: 
______________________________________ 
Substance Quantity (phr) 
______________________________________ 
Polymer 100 
Carbon black N 660 
65 
Sunpar 2280 22 
Stearic acid 1 
Zinc oxide 5 
Sulphur 1.8 
Vulkacit Merkapto (MBT) 
0.5 
Vulkacit Thiuram (TMTD) 
1 
______________________________________ 
A comparison compound was produced in accordance with the same formulation 
using Polysar Butyl 301 as the polymer. Both compounds were compared with 
each other both in the unvulcanised and the vulcanised (10 min at 
180.degree. C.) state. The results are summarised in the following tables. 
______________________________________ 
Property Butyl 301 Example 7 
______________________________________ 
Unvulcanised 
Mooney relaxation (30 sec at 100.degree. C.) (%) 
4.9 10.8 
Mooney scorch at 135.degree. C. 
17.5 14.1 
Green strength 100% (MPa) 
0.3 0.29 
Green strength 300% (MPa) 
0.23 0.3 
Vulcanisation: Monsanto Rheometer MDR 2000 at 180.degree. C. 
MIN 1.35 1.25 
Ts1 1.09 1.01 
T50 1.89 1.87 
T90 5.73 5.53 
MH 10.58 10.05 
Vulcanised 
Tear strength (MPa) 12.62 11.71 
Elongation at break (%) 
623 549 
100% modulus (MPa) 1.55 1.86 
300% modulus (MPa) 4.99 5.99 
Hardness at 23.degree. C. 
53 54 
Air permeability at 65.degree. C. 
4.85 4.79 
______________________________________