Process for the polymerization or copolymerization of butadiene in the presence of solid particles insoluable in the reaction medium

A process for preparing 1,4-cis polybutadiene or butadiene copolymers with other related diolefins by the catalytic polymerization or copolymerization of butadiene monomer, in the absence or substantial absence on solvents or diluents, said process comprising:

• preparing a catalytic mixture by placing in contact in an inert hydrocarbon vehicle:
• (a) at least one neodymium compound selected from neodymium oxide, alcoholates, phenates and carboxylates or mixtures thereof with other rare earth elements;
• (b) at least one organic compound containing alcoholic or phenolic hydroxyl groups or carboxyl, selected from alcohols, phenols and carboxylic acids, and optionally water;
• (c) at least one halogenated compound, selected from secondary or tertiary alkyl halogenides, aryl or alkylaryl halogenides, halogenides of organic acids, metallic or organometallic halogenides, and halogens;
• (d) at least one organometallic aluminum compound or hydride derivatives thereof;
• wherein the amount of compounds (a) and (b) are such that the ratio between the hydroxyl groups including those of water and/or carboxyl groups and the neodymium atoms is from 2/1 to 80 and maintaining contact of said components in order to obtain a catalytic mixture having an aluminum/neodymium ratio of from 20/1 to 80/1 and a halogen/neodymium ratio of from 0.2/1 to 3/1,
• feeding said catalytic mixture and liquid butadiene monomer separately or premixed in an amount of from 10.sup.4 to 4.10.sup.5 g.mols of butadiene per g.atom, either discontinuously in an agitated polymerization reactor, or continuously at one end of an elongated reactor in which flowing of the polymerization mixture is carried out by a piston ("plug-flow") in the presence of solid particles insoluble in the reaction medium,
• controlling the temperature of the polymerization reaction through the partial evaporation of the butadiene monomer from the liquid phase of polymerization until a polymer mixture with a polymer content of approximately 25 to approximately 70% by weight is obtained,
• discharging the polymer from the other end of the reactor, and
• separating and recovering 1,4-cis polybutadiene from said discharged mixture.