PROCEDE DE PREPARATION DE CAOUTCHOUC DE POLYBUTADIENE A RESISTANCE MECANIQUE AMELIOREE

SELON L'INVENTION LA TENEUR EN EAU D'UNE SOLUTION DE 1,3-BUTADIENE DANS UN SOLVANT ORGANIQUE INERTE EST AJUSTEE ENTRE 0,2 ET 5 MILLIMOLES PAR LITRE DE SOLUTION DE 1,3-BUTADIENE; UN PREMIER MELANGE DE POLYMERISATION EST PREPARE EN 4 A PARTIR DE LA SOLUTION DE 1,3-BUTADIENE AJUSTEE, D'UN COMPOSE DE COBALT; LE PREMIER MELANGE DE POLYMERISATION EST SOUMIS EN 5 A UNE POLYMERISATION CIS-1,4; UN SECOND MELANGE DE POLYMERISATION COMPRENANT LE CIS-1,4-POLYBUTADIENE RESULTANT, DU 1,3-BUTADIENE QUI N'A PAS REAGI, LE SOLVANT ORGANIQUE INERTE, ET UN CATALYSEUR CONSTITUE D'UN COMPOSE D'ALUMINIUM ORGANIQUE, D'UN COMPOSE DE COBALT ET DE DISULFURE DE CARBONE EST SOUMIS EN 6 A UNE POLYMERISATION 1,2, POUR PRODUIRE UN CAOUTCHOUC DE POLYBUTADIENE AYANT DE 5 A 30 EN POIDS D'UNE FRACTION INSOLUBLE DANS LE N-HEXANE BOUILLANT ET DE 70 A 95 EN POIDS D'UNE FRACTION SOLUBLE DANS LE N-HEXANE BOUILLANT ET POSSEDANT UNE EXCELLENTE RESISTANCE MECANIQUE; PUIS LA REACTION DE POLYMERISATION 1,2 EST BLOQUEE EN 40 ET LE CAOUTCHOUC DE POLYBUTADIENE RESULTANT EST ISOLE EN 7 DU MELANGE DE POLYMERISATION 1,2. A polybutadiene rubber having an enhanced mechanical strength is produced in such a manner that the content of water in a solution of 1,3-butadiene in an inert organic solvent is controlled to 0.2 to 5 millemoles per liter of 1,3-butadiene; a first polymerization mixture is prepared from the controlled 1,3-butadiene solution, an organic aluminum compound of the formula Al RnX3-n, wherein R=C1-6 alkyl, phenyl, or cycloalkyl, X=halogen, and n=1.5-2.0, and a cobalt compound, for example, by aging a mixture of the controlled 1,3-butadiene solution with the aluminum compound for at least one minute and then by admixing the aged mixture with the cobalt compound; the first polymerization mixture is subjected to a cis-1,4-polymerization; a second polymerization comprising the resultant cis-1,4-polybutadiene, non-reacted 1,3-butadiene, the inert organic solvent, and a catalyst comprising an organic aluminum compound of the formula AlR3, a cobalt compound, and carbon disulfide is subjected to a 1,2-polymerization to produce a polybutadiene rubber consisting essentially of 5% to 30% by weight of a boiling n-hexane-insoluble fraction and 70% to 95% by weight of a boiling n-hexane-soluble fraction thereof and having an excellent mechanical strength; and after the 1,2-polymerization is shortstopped, the resultant polybutadiene rubber is isolated from the 1,2-polymerization mixture.