Snamprogetti S.p.a.

Enichem Elastomeri S.p.a.

Snamprogetti

Mario Bruzzone

Alberto Greco

Sebastiano Cesca

Guglielmo Bertolini

Piero Andreussi

Silvano Gordini

Renzo Bianchi

Ken Wyllie

The processability of a polybutadiene with a high content of 1,4-cis-structure is improved by means of the addition of PCl.sub.3 before the polymerization reaction is quenched and when Mooney viscosity of polybutadiene has reached a prefixed value, preferably lower than, or equal to 30; the polymerization of butadiene is carried out in a solution in an aliphatic or cycloaliphatic solvent, in the presence of a catalytic system based on rare earths, preferably a neodymium-based catalytic system.

Method for preparing polybutadiene endowed with improved processability

The invention relates to a continuous process for the manufacture of butyl rubber in which the monomers are polymerized using a halogenated polymerization medium in a self-cleaning screw extruder at a constant pressure under boiling plug-flow conditions by means of a modified aluminium halide catalyst which operates at high temperature (relative to prior art very low temperatures of e.g. -100.degree. C.). In contrast to prior art slurry processes, the polymerization mixture forms a sticky, highly viscous mass which is conveyed by screw action to the extruder outlet as polymerization proceeds. The butyl rubber product is separated at a high concentration from vapors of unreacted monomers and polymerization medium which are recycled. Cooling is effected by vaporization of a portion of the mixture of monomers and polymerization medium in a flash tank before supply to the extruder and returning the vaporized fraction and recycle vapors to the flash tank through, in succession, a compressor, heat exchanger and throttle valve. By using the process of the invention, the total energy consumption in butyl rubber manufacture can be cut to about 20% of that of prior art processes.

Manufacture of butyl rubber

An alpha-olefin such as ethylene is polymerized in the presence of a catalyst system consisting of (1) an alkyl-halide, alkyl-derivative or hydride of a metal belonging to one of the first three groups of the periodic system and (2) the combination product of a transition metal chloride and titanium trichloride, supported on a previously chlorinated material such as chlorinated .alpha.-alumina having a high superficial area.

Process for the polymerization of alpha-olefins, catalyst employed in

An alpha-olefin such as ethylene is polymerized in the presence of a catalyst system consisting of (1) an alkyl-halide, alkyl-derivative or hydride of a metal belonging to one of the first three groups of the periodic system and (2) the combination product of a transition metal chloride and titanium trichloride, supported on a previously chlorinated material such as chlorinated .gamma.-alumina having a high superficial area.

An alpha-olefin such as ethylene is polymerized in the presence of a catalyst system consisting of (1) an alkyl-halide, alkyl-derivative or hydride of a metal belonging to one of the first three groups of the periodic system and (a) the combination product of a transition metal chloride and titanium trichloride said transition metal chloride being derived from the reaction of a transition metal carbonyl and titanium tetrachloride.

Alpha olefin polymerization catalyst comprising an alkyl halide and a

Ethylene is polymerized through the use of an improved catalyst system consisting of a carrier such as neodymium oxide having a high superficial area, an aluminum compound such as triisobutylaluminum and the combination product of titanium trichloride and an isostructural chloride of another transition metal prepared by impregnating the carrier with a solution of a carbonyl derivative of the other transition metal, refluxing the impregnated carrier with titanium tetrachloride until that carbonyl derivative is converted to the chloride of the other transition metal, and then removing the excess of titanium tetrachloride.

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San Donato Milanese, Italy

Mario Bruzzone