MXPA97005110A - New initiator system, containing vanadio, for the (co) dimerization of iso-olefi - Google Patents

Abstract

The invention relates to an initiator system for the polymerization of iso-olefins with 4 to 16 carbon atoms, optionally with monomers polymerizable with iso-olefins, constituted by one or more aromatic or heteroaromatic hydrocarbons, polycyclic, and by an organic solution , aged, of vanadium tetrachloride, the concentration of vanadium tetrachloride being from 0.01 mmol to 500 mmol per liter of solvent and the molar ratio between aged vanadium tetrachloride and polycyclic hydrocarbons in the range of 100: 1 to 1 being found: 100 With the aid of the initiator system according to the invention, it is possible to produce polyiso iso-olefins, especially butyl rubbers, at relatively high temperatures with only a small gel content and a sufficiently high molecular weight.

Description

NEW INITIATOR SYSTEM, OUE CONTAINS VANADIO. FOR THE (CO) DIMERIZATION OF ISO-OLEFINS. DESCRIPTION OF THE INVENTION The object of the present invention is a novel initiator system, "containing vanadium, for the (co) polymerization of. iso-olefins, a process for obtaining the new initiator system and its use for obtaining polymers constituted by iso-olefins with, if appropriate, monomers copolymerizable with iso-olefins, especially for the production of butyl rubbers. The currently obtained obtaining process for butyl rubber is known, for example, from the publication Ullmanns Encyclopedia of Industrial Chemistry, Vol. A. 23, 1993. The embodiment of the cationic copolymerization of isobutene with isoprene in the slurry process and with Methylene chloride as the process solvent is carried out with aluminum chloride as an initiator with the addition of small amounts of water or hydrochloric acid. The initiation of this copolymerization is conventionally known by means of a combination of tertiary halides in combination with Lewis acids (Kennedy, Marechal: Carbocationic Polymerisation, Wiley 1982). Both methods have in common that, in order to obtain a molecular weight, sufficiently high for use in the rubber processing industry, polymerization temperatures of about -100 ° C are required, which requires a cooling of the REF: 25129 very expensive reaction. In this case, the rule that, as the temperature increases, the molecular weights become smaller and smaller. It is also known to copolymerize isobutene with different comonomers at temperatures of about -40 ° C with. vanadium tetrachloride as initiator, which is used, as desired, pure or as a solution in heptane and, if appropriate, is activated by light or by 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); , M. Marek: Makromol, Chem. 177. 3325-3343 (1976), M. Marek et al., US 3,997,417, L. Toman, M. Marek, J. Macromol, Sci. -Chem., A15 (8), 1533-1543 (1981), M. Marek: J. Polym, Sci. Symp. 5.6, 149-158 (1976)). The copolymers made with this process certainly have a rubbery consistency but are nonetheless insoluble as a result of a high proportion of gel and precipitate during the polymerization in al-coholic or bulk solution, which leads to serious problems in the case of a industrial realization of this reaction. The homopolymerization of isobutene with vanadium tetrachloride as an initiator and with ammonia (L. Toman, M. Marek, Polymer Bull, 6, 570-578 (1982)) as a co-initiator has been described in mass and in solution (heptane solvent) . The polymerization was carried out in the temperature range from -10 ° C to -75 ° C in the dark. The polymerization is not verified in this case without the presence of ammonia. The yields depend on the molar ratio between vanadium tetrachloride / ammonia and reach a maximum at a ratio of 1: 1. The molecular weights obtainable are independent of this proportion and increase as the monomer concentration increases. In the case of mass polymerization at -75 ° C, a molecular weight (determined by viscosity) of 2.015 kg / mol was obtained. In heptane at a monomer concentration of 4.65 mol / l, the value was only half that previously indicated. The molecular weights obtained decrease as the temperature increases. Other properties of the polymers, especially the gel content, have not been indicated. It is also known from US 3,326,879 the polymerization of olefinic hydrocarbons with vanadium tetrachloride in combination with the most diverse aromatic compounds as co-initiators in the temperature range from -110 ° C to + 110 ° C. The procedure described in the specification of the cited North American patent has the disadvantage that "some of the co-initiators indicatedwhen they are used in a proportion greater than 100% in moles, they prevent polymerization and, as shown by their own tests, copolymers of isobutene with isoprene are obtained only with a high content of gel. This also applies to the process described in the specification of US Pat. No. 3,997,417 for the polymerization and copolymerization 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 of -140 ° C to + 30 ° C. Thus, according to example 12, isobutylene and isoprene copolymers having a gel content of 15% and, according to example 11, copolymers of isobutylene and butadiene having a gel content of 10% are obtained. . The molecular weights are between 75 and 550 kg / mol according to the test conditions. It is also unsuitable for the polymerization or for the copolymerization of mono-olefinic and di-olefinic compounds, the polymerization process described in US Patent 3,998,713 using tetravalent metal halides in combination with alkaline (earth) metals or its hydrides or amalgams as co-initiators under irradiation in the temperature range from 0 ° C to -140 ° C. Also in this case a high gel content is obtained during the polymerization. The molecular weights of the polymers are satisfactory even at low temperatures. The same is true for the polymerization and copolymerization, described in DE 2 125 800 and DE 2 119 305, of monomers with olefinic double bonds in the presence of, for example, tetravalent vanadium halides with or without light. The molecular weights obtained from the polymers are unsatisfactory and the gel content of the polymers is, for example, too high in the case of obtaining butyl rubbers. It has now surprisingly been found that the aforementioned disadvantage in the (co) polymerization of iso-olefins can be avoided if the (co) polymerization of iso-olefins is carried out in the presence of the initiator system, which contains vanadium, described then. The object of the present invention is, therefore, an initiator system for the polymerization of iso-olefins with 4 to 16 carbon atoms, optionally with monomers copolymerizable with iso-olefins, constituted by one or more aromatic hydrocarbons or heteroaromatics, polycyclic (co-initiator) and by an organic, aged solution of vanadium tetrachloride initiator), the concentration of vanadium tetrachloride being 0.01 mmol to 500 mmol per liter of solvent and the molar ratio of tetrachloride being found of aged vanadium with respect to polycyclic hydrocarbons in the range of 100: 1 to 1: 100. As co-initiators, aromatic or heterocyclic, polycyclic or at least bicyclic hydrocarbons, alone or in combination, will be used in the initiator system according to the invention. The polycyclic aromatic or heteroaromatic hydrocarbons may optionally be substituted with alkyl or alkylene groups. Other possible substituents are halogen, cyano groups, nitro groups, alkoxy groups as well as phenyl groups, optionally substituted. The aromatic or heteroaromatic bi-, tri- and tetracyclic hydrocarbons will be preferred. Examples of suitable co-initiators are, for example, naphthalene, anthracene, indene, coumaron, carbazole, N-vinylcarbazole, biphenyl, p-terphenyl, acenaphthene, acenaphthylene, fluoranthene, fluorene, phenanthrene, pyrene, and octylated diphenylamine. (Vulkanox OCD from BAYER). The conditions for the aging of the initiator depend on the solvent used. Suitable solvents for the aging of the initiator in the sense of the invention are hydrocarbons, especially aliphatic and / or aromatic hydrocarbons without functional substituents with 4 to 20 carbon atoms and with a boiling point above -20 °. C. Solvents with a boiling point situated above about + 20 ° C and with a melting point below 20 ° C will be preferred., solvents will be especially preferred • with a melting point below 0 ° C. These solvents can be used alone or in combination with each other. Examples of such hydrocarbons are: pentane, hexane, 2, 3-dimethylbutane, heptane, cyclopentane, cyclohexane and / or methylcyclohexane, pentane and / or hexane are particularly preferred. The aging of the initiator can be carried out, in principle, within a wide range of temperatures and will be limited basically only by the melting point and by the boiling point of the solvent used. A temperature range from 0 to 40 ° C, particularly preferably from +10 to 20 ° C, will be preferred. Aging can be carried out in the presence of light or in the dark. Preferably work under daylight or under artificial light (in the visible or ultraviolet range). The optimum aging time depends on the solvent used, the temperature, the amount of light and the concentration of the solution. Aging times are possible from a few minutes to several weeks, aging times will be preferred from a few hours to a few days, aging times from one hour to 24 hours, especially 24 hours, will be especially preferred. The aging of vanadium tetrachloride in the corresponding organic solvent can be carried out in the absence or in the presence of the co-initiators. In a preferred embodiment, aging is carried out in the absence of the co-initiators. Thus, the object of the invention is a process for obtaining the initiator system described above, characterized in that the vanadium tetrachloride is dissolved in one of the organic solvents described above and the solution thus prepared is subjected to an aging process. in the presence of light or in the absence of light, the concentration of vanadium tetrachloride being 0.01 mmol to 500 mmol per liter of solvent.

Another object of the invention is the use of the initiator system for the preparation of poly-iso-olefins, by polymerization of iso-olefins with 4 to 16 carbon atoms, optionally with conjugated diolefins- with 4 to 6 carbon atoms and / or cationically polymerizable mono- or poly-unsaturated compounds with 4 to 16 carbon atoms, at temperatures of -100 ° C to + 20 ° C, preferably -60 ° C to 0 ° C, especially -45 ° C to -15 ° C, and pressures from 0.001 to 70 bar, preferably from 0.1 to 2 bar. To remove impurities, especially moisture during polymerization, alkali metals and alkaline earth metals, their amalgams with mercury or hydrides of the metals of the groups can be added to the mixture of the monomers, if appropriate as drying agents. I., II., III. and IV. of the periodic system. In this way, the amount of catalyst required can be reduced. The concentration of the aged vanadium tetrachloride is preferably from 0.01 mmoles to 500 mmoles per liter of solvent. The molar ratio between the aged vanadium tetrachloride and the above-mentioned polycyclic hydrocarbons is preferably in the range of 10: 1 to 1:10. As iso-olefins having 4 to 16 carbon atoms, preferably with 4 to 8 carbon atoms, there will be mentioned, for example: isobutene, 2-methylbutene-1,3-methyl-butene-1,4-methylpentene-. and ß-pinene, preferably isobutene and 2-methylbutene-1; in the form of diolefins conjugated with 4 to 6 carbon atoms: isoprene, butadiene, 2,3-dimethylbutadiene, cyclopentadiene, methylcyclopentadiene, 1,3-cyclohexadiene, preferably isoprene, and as organic compounds, cationically polymerizable, mono or poly - unsaturated with 4 to 16 carbon atoms, preferably with 4 to 10 carbon atoms: styrene, 4-methylstyrene, divinylbenzene, α-methylstyrene, dimethyl fulvene, preferably 4-methylstyrene and divinylbenzene. When copolymerization of the mentioned iso-olefins with the mentioned conjugated diolefins and / or organic compounds must be carried out according to the process of the invention., cationically polymerizable, mono- or poly-unsaturated, a weight ratio between iso-olefins and diolefins and unsaturated organic compounds from 95: 5 to 99.5: 0.5 will be preferred. The polymerization can be carried out in principle at varying pressures. In this case both an overpressure and a reduced pressure are admissible. Preferably, the pressure is adjusted in such a way that the reaction mixture boils at the desired reaction temperature and, therefore, the heats of reaction, formed during the polymerization, can be dissipated by boiling cooling. The ideal pressure will be determined by the boiling point and by the amount of the solvent used, by the boiling point of the monomers used as well as by the temperature of the desired reaction. If, for example, you work without solvent (polymerized in bulk), the ideal pressure will be calculated according to the following formula: p = 49071249, 2 * e "2869 / T In this formula T means the temperature of the reaction in Kelvin and p means the pressure in milli-bars. The pressure actually used can deviate in particular cases to values up to 100 mbar both above and below this ideal value. Deviations < 50 mbar, especially preferred deviations from < 20 mbar. The polymerization can be carried out according to either a continuous or discontinuous process form. In a preferred embodiment, the polymerization will be carried out in the batchwise manner, for example in the following manner: The reactor, pre-cooled to the reaction temperature, is charged with the solvent, with the co-initiator with the monomers. The initiator is then pumped at a rate of 1 ml / hour to 1,000 ml / hour, until an exothermic reaction is established. All operations will be carried out under protective gas or under a slight vacuum. The development of the reaction is followed by thermal detachment. Once finished the exothermic reaction is stopped with a phenolic antioxidant, such as for example 2,6-di-tert. -butyl-4-methyl-phenol, dissolved in ethanol. For the polymerization according to the invention it is of great importance to use the hydrocarbon solution of aged vanadium tetrachloride (initiator) in combination with the co-initiators mentioned. Suitable solvents for the polymerization in the sense of the invention are aliphatic and / or aromatic hydrocarbons (optionally halogenated) without functional substitutes. Solvents with a melting point below 20 ° C will be preferred. Solvents with a melting point below 0 ° C will be particularly preferred. Examples of suitable aliphatic solvents are: methyl chloride, methylene chloride, chloroform, carbon tetrachloride, propane, butane, pentane, hexane, 2,3-dimethylbutane, hepfyl, cyclohexane, methylcyclohexane, chloroethane, 1,1-dichloroethane, 1,2-dichloroethane, 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, l-chloro-2-methyl-propane, 1-chloropentane, 2, -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-trimethylbenzene, 1,3,5-trimethylbenzene, diethylbenzene , 1, 2, 3, 4-tetramethylbenzene, 1, 2, 3, 5-tetramethylbenzene, 1, 2, 4, 5-tetramethylbenzene, pentamethylbenzene, 1-iso-propyl-4-methylbenzene, 1,3 -di-isopropylbenzene, 1,4-di-iso-propylbenzene, 1-tert. -butyl-3, 5-dimethylbenzene and / or 1,3,5-tri-isopropylbenzene. It is particularly surprising that with the aid of the initiator system according to the invention, constituted by an aged organic solution of vanadium tetrachloride (initiator) in combination with one or more aromatic hydrocarbons or polycyclic heteroaromatics (co-initiator), it is possible to obtain poly-iso-olefins, especially butyl rubbers, at relatively high temperatures (-40 ° C) with only a very small gel content and with a sufficiently high molecular weight, even though according to the state of the art it was expected that , when vanadium tetrachloride was used as the initiator, the polymerization of iso-olefins was related to a relatively high gel content, often combined with a molecular weight not high enough for rubber applications. And emploß. Experimental details The gel content was determined in toluene after a dissolution time of 24 hours at 30 ° C with a sample concentration of 12.5 g / 1. The separation of the insoluble part was carried out by ultracentrifugation (one hour at 20.0000 revolutions / minute and 25 ° C). The viscosity of the solution? of the soluble part was determined in toluene at 30 ° C by capillary viscometry of Ubbelohde. The molecular weight Mv calculated from the viscosity of the solution was determined according to the following formula: In (Mv) = 12.48 + 1.565 * ln? . The GPC tests with the help of the combination GPC-Viscometry was carried out on an instrument that was equipped with 8 Styragel columns of sizes 100, 1000 (2x), 104 (2x), 105 (2) and 106 nm. The total length of the column is 976 cm. The eluent THF was pumped at 0.5 ml / minute. Fractions of 1.93 ml on-line were measured in an Ubbelohde viscometer. The My values. were calculated with the constants K = 5 x 10"4 dl / gya = 0.6 The evaluation was carried out by means of universal calibration according to Benoit with PC-Software of the firm Kirschbaum S Schroeder GmBH. Mooney was verified after 8 minutes at a temperature of 125 ° C. The measurement of the UV spectra of the catalyst solutions was carried out with a UV spectrometer from Perkin-Elmer at room temperature with a catalyst solution without dilution in a cuvette with a layer thickness of 0.01 mm.

The solvents used were distilled, insofar as they were not indicated otherwise, prior to their use, for the purification, under an argon atmosphere, through calcium hydride. The isobutene used in the polymerizations was passed, for drying, through a column filled with sodium on aluminum oxide. The isoprene used was filtered, for the elimination of the stabilizer, under argon through a column with anhydrous aluminum oxide and used in this form for the polymerization. The other comonomers used were distilled, prior to their use, for purification, under an argon atmosphere through calcium hydride. Initiator synthesis (aging of UCl ^). Example 1. 500 ml of hexane were placed under argon. 24.1 g (0.125 mol) of vanadium tetrachloride were added. The solution was subjected for 7 days, under slight agitation, to the daylight, observing an intensified clearing of the red coloration and the appearance of small amounts of a solid product. The amount of this color change can be recognized by comparing the UV spectra, which have been jointly represented in Figure 1 in which "UV spectra are shown as a function of aging duration.

The precipitated solid product (< < < 1%) was removed by filtration under argon. The remaining solution was stored under argon and was used in this form for the initiation of the polymerization. When properly stored, this solution can be used for several weeks. The slight turbidity, which eventually occurs during storage, can be eliminated by filtration. Example 2. Analogous to Example 1, the aging time was in this case 2 hours. Example 3. 100 ml of 2,3-dimethylbutane were placed under argon. 4.8188 g (0.025 mole) of vanadium tetrachloride was added. The solution was subjected during 9 days, under slight agitation, to the daylight, observing an intensified clearing of the brown color and the appearance of small quantities of a solid product. The precipitated solid product was removed by filtration under argon. The remaining solution was used in this form for the initiation of the polymerization. Example 4. 500 ml of dried toluene are combined by distillation of LiAlH4 at room temperature with 125 mmole of VC14 and stirred for 2 hours. The formed slurry becomes deep black. The precipitate is separated by filtration.

Use 5. 50 ml of dried methylcyclohexane are combined by distillation of CaH2 at room temperature with 12.5 mmole of VC1 and stirred for 24 hours. The clear solution has an intense red color and is used without filtration for polymerization. Example 6. 100 m-1 of dried heptane are combined by distillation of CaH2 under argon with 25 mmole of VC14 and stirred for 24 hours. It results in a clear dark red solution. Polymerizations Example 7. 500 g of isobutene and 11.918 g (1.96 mol%) of isoprene were placed under argon under the exclusion of light at a temperature of -40 ° C. 0.036 g of anthracene and 1.6 ml of the initiator solution of the example were added. 1. After a reaction time of 15 minutes, the exothermic reaction was stopped, due to the moment of viscosity, by the addition of a pre-cooled 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. The precipitated polymer was washed with 2.5 liters of methanol after separation by decanting the liquid, rolled to give a thin skin and dried under vacuum at 50 ° C for one day (yield: 91.3 g = 17.8 %).

The slightly brown polymer, thus obtained, had a Mooney value of 55, a gel ratio of 3.1% and a Staudinger index of 1.0632 dl / g. Example 8 (comparative example). 600 g of isobutene and 13.63 g (200 mmoles) of isoprene were placed under argon at a temperature of -40 ° C. In the presence of light, 4 ml of the initiator solution of Example 2 were added. After a reaction time of 15 minutes, the exothermic reaction was stopped, due to the increase in viscosity, by the addition of a pre-cooled 1 gram solution. of 2, 2'-methylene-bis (4-methyl-6- tert.-butylphenol) (Vulkanox BKF from Bayer AG Leverkusen) in 250 ml of ethanol. The precipitated polymer was washed with 2.5 liters of methanol after separation by decanting the liquid, rolled to give a thin skin and dried under vacuum at 50 ° C for one day (yield: 92.6 g = 15%). The slightly brown polymer, thus obtained, had a Mooney value of 98, a gel ratio of 43%. The Staudinger index of the soluble parts was 1.55 dl / g. Example 9. The polymerization was repeated, from "Example 7, with the difference that, instead of the initiator of Example 1, the initiator solution of Example 3 was used. Yield: 110 g = 21.5%.

The polymer thus obtained had a Mooney value of 60.5, a gel content of 3.5% and a Staudinger index of 1.359 dl / g. Example 10 (comparative example). The polymerization of Example 7 was repeated, with the difference that, instead of the initiator of Example 1, the quantitative amount of vanadium tetrachloride dissolved in hexane was used. Yield: 124 g = 24%. The polymer thus obtained had a Mooney value of 65, a gel ratio of 23.3% and a Staudinger index of 0.64 dl / g. Example 11. 598 g of isobutene and 13.63 g (200 mmoles) of isoprene were placed under argon at a temperature of -40 ° C. In the presence of light, 8 ml of the initiator solution was added, prepared analogously to that of example 1 with an aging time of 96 hours. After a reaction time of 20 minutes, the exothermic reaction was stopped due to the increase in viscosity, by adding a pre-cooled 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.) The precipitated polymer was washed with 2.5 liters of methanol after separation by decanting the liquid, rolled to give a thin skin and dried under vacuum at 50 ° C for 1 day. (Yield: 74.2 g »12.1%).

The slightly brown polymer, thus obtained, had a Mooney value (125 ° C, 1 + 8 ') of 30 and a gel ratio of 43%. The Staudinger index of the soluble parts was 0.6 dl / g. Example 2. 600 g of isobutene and 13.63 g (200 mmoles) of isoprene were placed under argon at a temperature of -40 ° C. 10 ml of the initiator solution, prepared analogously to that of Example 6, with an aging time of 168 hours, were added, under exclusion of the light. After a reaction time of 17 minutes, the exothermic reaction was stopped due to the increase in viscosity by the addition of a pre-cooled 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. The precipitated polymer was washed with 2.5 liters of methane after removal by decanting the liquid, rolled to give a thin skin and dried under vacuum at 50 ° C for 1 day. (yield: 61.4 g = 10%). The slightly brown polymer, thus obtained, had a Mooney value (125 ° C, 1 + 8 ') of 94 and a gel ratio of 37%. The Staudinger index of the soluble parts was 1.64 dl / g. Example 13. 600 g of isobutene and 13.63 g (200 mmoles) of isoprene were placed under argon at a temperature of -40 ° C.

In the presence of light, 8 ml of the initiator solution, prepared analogously to that of Example 4, were added with an aging time of 2 h. After a reaction time of 15 minutes, the exothermic reaction was stopped due to the increase in viscosity by the addition of a pre-cooled solution of one gram of 2,2'-methylene-bis (4-methyl-6-tert. butylphenyl) (Vulkanox BKF from Bayer AG Leverkusen) in 250 ml of ethanol. The precipitated polymer was washed with 2.5 liters of methanol after separation by decanting the liquid, rolled to give a thin skin and dried under vacuum at 50 ° C for 1 day (yield: 76.7 g = 12.5% ). The slightly brown polymer thus obtained had a Mooney value (125 ° C, 1 + 8 ') of 77 and a gel ratio of 49%. The Staudinger index of the soluble parts was 1.36 dl / g. Example 14. Analogous to example 13; the polymerization was carried out in the absence of light. The yield was: 59.6 g = 9.7%. • The slightly brown polymer, thus obtained, it had a Mooney value (125 ° C, 1 + 8 ') of 7.5 and a gel ratio of 59%. The Staudinger index of the soluble parts was 1.0 dl / g. Example 15. 1,000 n-hexane, 200 g of isobutene and 75 mmoles) of isopropene were placed at -40 ° C under argon and combined with 20 ml of initiator solution analogous to that of example 5. After 120 minutes of agitation at -40 ° C a conversion of 52% was achieved. The product has a gel content of 30%, the Staudinger index of the soluble parts was 0.37 dl / g. The polymer had a sticky consistency. A M ^ = 400 kg / mol and a Mn = 8 kg / mol were completed with the help of gel permeation chromatography. The proportion of branched polymers with long chain was determined with a value of 5%. Example 16. (effect of various aging agents). To demonstrate the effect of the various aging times of the initiator on the results of the polymerization, the polymerization of Example 9 was repeated with the initiator of Example 3 used for different times being aged. The results have been summarized in the following table.

Example 17 (Polymer assays). In accordance with the routine of Example 7, 500 g of polymer was prepared. The material had a Mooney value, a gel proportion of 2.1%, an Mn of 31.8 kg / mol, a t of 8590.7 kg / mol and an isoprene content of 2.2% in mo¬ them. From this polymer a rubber mixture was made on a laboratory cylinder according to the following recipe: According to the same recipe a comparative mixture was prepared with Polysar Butyl 301 as a polymer. Both mixtures were compared with each other both in the unvulcanized state and in the vulcanized state (10 minutes at 80 ° C). The results have been gathered in the following tables. in vulcanization.

Vulcanization: MDR 2000 meter at 180 ° C. Vulcanized.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (3)

1. CLAIMS 1. Initiating system for the polymerization of iso-olefins with 4 to 16 carbon atoms, optionally with monomers polymerizable with iso-olefins, constituted by one or more aromatic or heteroaromatic hydrocarbons, polycyclic, and by an organic solution, aged, of vanadium tetrachloride, the concentration of vanadium tetrachloride being from 0.01 mmol to 500 mmol per liter of solvent and the ratio between aged vanadium tetrachloride and polycyclic hydrocarbons in the range of 100: 1 to 1 being: 100
2. 2. Process for obtaining the initiator system according to claim 1, characterized in that the vanadium tetrachloride is dissolved in an organic solvent and the solution thus obtained is subjected to an aging process in the presence of light or in the absence of light. .
3. 3. Use of the initiator system claimed in claim 1, for the preparation of (co) polymers of iso-olefins with 4 to 16 carbon atoms with optionally copolymerizable monomers with iso-olefins, especially for the production of butyl rubbers. .