Patentamt Europaisches || || 1 1| || || || || || || 1 1| || || (19) J European Patent Office Office europeen des brevets (11) EP 0 770 631 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication:ation: (51) |nt. CI.6: C08F 136/06, C08F 4/70 02.05.1997 Bulletin 1997/18 (21) Application number: 96202878.3 (22) Date of filing: 16.10.1996 (84) Designated Contracting States: (72) Inventors: AT BE CH DE DK ES Fl FR GB GR IE IT LI NL PT • Van der Arend, Johannes C. M. SE 1031 CM Amsterdam (NL) • De Boer-Wildschut, Marijke (30) Priority: 18.10.1995 EP 95307411 1031 CM Amsterdam (NL) • Van der Huizen, Adriaan Albert (71) Applicant: SHELL INTERNATIONALE RESEARCH 1031 CM Amsterdam (NL) MAATSCHAPPIJ B.V. • Kersten, Maria Johanna Elisabeth 2596 HR Den Haag (NL) 1031 CM Amsterdam (NL) (54) Manufacturing process for high cis poly(butadiene) (57) Process for the manufacture of linear, substan- tially gel free high as 1 ,4 poly(butadiene), comprising the polymerisation in the presence of a catalyst, com- prising at least one cobalt compound, at least one orga- noaluminium compound, water, and in the presence of a cycloalkane as main solvent component, containing at least one substituted benzene as polymerisation regula- tor, characterised in that as polymerisation regulator compounds of the general formula wherein n is an integer in the range of from 3 to 5. wherein each R represents a lower alkoxy group con- taining from 1 to 6 carbon atoms. < CO CO o r»- o Q_ LU Printed by Rank Xerox (UK) Business Services 2.14.4/3.4 EP 0 770 631 A1 Description The invention relates to a manufacturing process for high cis poly(butadiene) . More in particular the invention relates to a process for the manufacture of cis-1 ,4-poly(butadiene) by polymerising 1 .3 butadiene, in the presence of a 5 catalyst comprising a mixture of a cobalt compound, at least one organoaluminium compound and water. Many commercial processes are known to produce high-cis polybutadiene in a continuous way in an aromatic sol- vent like toluene or benzene. However, due to environmental concerns these solvents tend to be replaced by aliphatic solvents like cyclohexane. In these solvents the polymerisation control tends to be troublesome, leading to deviations in the required polymer structure and, eventually, to increased gel content of the product. 10 Therefore, polymerisation control agents (polymerisation regulators) have been developed as known from e.g. the British Patent Application No. 2035341 . Said application actually was disclosing that with the use of a cycloalkane hav- ing 5 to 8 carbon atoms, and in particular cyclohexane, as main solvent in the polymerisation of butadiene, the polym- erisation proceeded too rapidly, as a result of which it was difficult to control the polymerisation temperature, and as a consequence providing a high cis-poly(butadiene) of lower linearity, which did not show the desired physical properties. 15 In order to avoid this disadvantage, a small amount, i.e. from 0.1 to 2 wt% relative to the weight of cycloalkane, of an alkyl substituted benzene was used, which slowed down the initial polymerisation rate, so that it could be easily con- trolled whereas the use of significant amounts of aromatic solvents such as benzene, toluene and the like could be avoided too. The alkyl substituted benzene polymerisation regulator applied in said process had 1 to 4 alkyl substituents with 20 each substituent having from 1 to 4 carbon atoms and preferably two or three methyl or ethyl groups. As specific examples of said alkyl substituted benzene polymerisation regulator were mentioned: toluene, 0-, m-, p-xylene or a mixture of xylene isomers, 1 ,3,5-trimethylbenzene (mesitylene) and other isomers of trimethylbenzene, or a mixture thereof, 1 ,2,4,5 tetramethylbenzene(durene) or other isomers of tetramethylbenzene (isodurene) or a mixture thereof, ethylbenzene, 1 ,2-, 1 ,3- or 1 ,4-diethylbenzene or a mixture of said isomers, n-propylbenzene 1 ,4-3-dipropyl- 25 benzene, n-butyl-benzene or a mixture of various alkyl substituted benzenes. As cobalt catalyst component were used any organic compound such as cobalt salts of organic acids cobalt com- plexes and, the cobalt compound preferably being soluble in the solvent or the monomer. As an organoaluminium catalyst component preferably was used an alkyl aluminium halide, which could be used as a mono- or dialkyl aluminium halide, a mixture thereof, or a mixture of R3AI,R2AIX, RA1X2, or AIX3 wherein R is alkyl 30 of 1 to 1 2 carbon atoms and X is halogen and more preferably chloride. As preferred aluminium to cobalt ratios were used those in the range from 50 to 300 and more preferably from 100 to 200. Trace amounts of water were also regarded as useful components of the polymerisation catalyst system, nor- mally added via either the solvents or the monomers. Although the alkyl-substituted benzenes may offer good polymerisation control in cyclohexane based feeds, still rel- 35 atively high levels of these compounds are needed to attain the required effects. This may be a draw-back in view of environmental concerns and acceptability of the product. More effective polymerisation regulators are therefore needed.which allow sufficient kinetic control and the production of polymers within the required (existing) specification limits, at very low concentration levels. Therefore, it was an object of the present invention to provide an improved process for the manufacture of cis-1 ,4 40 poly(butadiene) providing a standardised high quality polymer, which should contain an acceptable amount of toxic chemicals. As a result of extensive research and experimentation such a process aimed at has surprisingly been found. Accordingly the present invention relates to a process of polymerising butadiene-1 ,3 to produce primarily linear, substantially gel free cis-1, 4-poly(butadiene), comprising the polymerisation in the presence of a catalyst, comprising 45 at least one cobalt compound, at least one organoaluminium compound, water, and in the presence of a cycloalkane as main solvent component, containing at least one substituted benzene as polymerisation regulator, characterised in that as polymerisation regulator are used compounds of the general formula 50 55 wherein n is an integer in the range of from 3 to 5. wherein each R represents lower alkoxy group, containing from 1 to 6 carbon atoms and preferably 1 -4. 2 EP 0 770 631 A1 Examples of suitable modifiers may be selected from those having methoxy, ethoxy, isopropoxy, tert-butoxy, isobu- toxy, n-pentoxy or isopentoxy substituents or mixtures thereof. More preferred embodiments of presently proposed polymerisation regulators are those containing 3 or 4 of the hereinbefore defined lower alkoxy groups. More preferably compounds are used wherein 3 or 4 methoxy substituents 5 are present. The most preferred modifiers was found to be 1 ,3,5-trimethoxy benzene. It has been surprisingly found that the hereinbefore specified polymerisation regulators, and in particular 1 ,3,5-tri- methoxy benzene, could be used in a significantly smaller amount to provide the same effect, in comparison with the hereinbefore discussed prior art process, i.e. less than 0.1 wt% relative to the weight of the cycloalkane solvent. Con- w sequently the process of the present invention has been found to enable the manufacture of cis-1, 4-poly(butadiene) containing significantly smaller residual amounts of said regulator. Moreover, the use of the presently proposed modifiers has enabled the manufacture of poly(butadiene) rubbers, having a well controllable linearity index. The polymerisation regulators are in general used in amounts of 100 ppm or less and in particular in amounts of 15 from 5 to 60 ppm relative to the weight of the polymerisation feed (solvent/butadiene/butene). More preferably amounts of from 5 to 40 ppm are used. The hereinbefore specified polymerisation regulators are known per se and are manufactured and/or marketed by e.g. APIN Chemicals Ltd., Milton Park, Abingdon, United Kingdom; Indofine Chemical Comp. Inc., Somerville, NJ 8876, USA; Penta Manufacturing Company, Fairfield NJ, USA; Air Products SA, 11760, Brussels, Belgium. 20 Examples of cycloalkanes useful in the process of the present invention are those having 5 to 8 and preferably 5 or 6 carbon atoms in the rings. They also include methyl and ethyl substituted cycloalkanes. Illustrative examples of said cycloalkanes are cyclopentane, cyclohexane, cycloheptane, cyclooctane, methylcyclopentane, methylcyclohexane, methylcycloheptane, methycyclooctane, dimethylcyclopentane, dimethylcyclohexane, dimethylcycloheptane, ethylcy- clopentane, ethylcylohexane, ethylcyclooctane or mixtures thereof. 25 Preferred are unsubstituted cycloalkanes. Most preferred solvents are cyclopentane or cyclohexane. One of the purposes of a solvent in this process is to control the polymerisation temperature by ref luxing the solvent and to keep dissolved the formed polymer. Often the desired temperature control is difficult to accomplish with only one solvent. However, by selecting two or more solvents which have certain desirable boiling points, the polymerisation tem- 30 perature can be relatively easily controlled. Therefore, the selection of the secondary solvent will depend primarily on its boiling point and the temperature that is to be maintained during polymerisation. Thus by "solvent" is meant either a cycloalkane solvent or a mixture of two or more solvents which is substantially free of aromatics and in particular ben- zene. In any event the monomer and the resulting polymer should be substantially soluble in the solvent. Useful sec- ondary solvents are saturated aliphatic hydrocarbons for example hexane, heptane or octane; olefins having 2 to 10 35 carbons for example butene-1 , pentene-1 or hexene-1 . Various ISOPAR solvents (sold by EXXON) are also found to be useful. They are a mixture of isoparaffinic hydrocarbon fractions boiling at certain temperature ranges. For example, ISOPAR C is primarily 2,2,4-trimethylpentane and other trimethyl pentane isomers.