Abstract: A solid component of catalyst for the (co)polymerization of ethylene and &agr;-olefins contains magnesium-carboxylate bonds and transition metal-carboxylate and can be represented by the formula: M1Mg(0.3-20)X(2-60)Al(0-6)(R—COO)(0.1-3)  (I) wherein: M is at least one metal selected from titanium, vanadium, zirconium and hafnium, X is a halogen excluding iodine, and R is an aliphatic, cycloaliphatic or aromatic hydrocarbon radical, containing at least 4 carbon atoms. A description follows of the preparation of a solid component of catalyst (I) and its use in procedures for the (co)polymerization of ethylene and &agr;-olefins.

Abstract: A solid component of catalyst highly active in the (co)polymerization of ethylene containing titanium, magnesium, aluminum, chlorine and alkoxy groups, and obtained by means of a procedure wherein:(i) a solid, granular support of magnesium chloride, obtained by spray-drying an alcohol solution of magnesium chloride, is suspended in a liquid hydrocarbon solvent and an aliphatic alcohol and a titanium tetraalkoxide are added to the suspension thus obtained,(ii) the suspension of step (i) is heated until a homogeneous solution is obtained and the solution is cooled to precipitate a granular solid in a relative suspension,(iii) the granular solid obtained in step (ii), in the relative suspension, is put in contact and reacted with an aluminum alkyl halide, and(iv) the solid component catalyst is recovered from the reaction products of step (iii).

Abstract: Ethylene homopolymers and ethylene copolymers with alpha-(C.sub.3 -C.sub.10)-olefins are obtained by polymerizing the monomers with a polymerization catalyst formed by:a) an alkyl-aluminum; andb) a modified solid catalyst component obtained by treating with a Lewis' base a non-modified solid component to be defined by means of the following formula, expressed as atomic proportions:Ti(1), hf(0.5-3), Si (1-6), Mg (0.5-15) Al (0.5-15),X (20-60, ROH (1-10)wherein:X represents either chlorine and bromine, andR represents either a linear or branched alkyl radical of from 1 to 6 carbon atoms.The catalyst is particularly useful for controlling the molecular weight and the molecular weight distribution of ethylene hompolymers and copolymers.

Abstract: A solid catalyst component for the low-pressure polymerization of ethylene and C.sub.3 -C.sub.10 alpha-olefins into very high molecular weight polyolefins is in the form of a spherical granular solid having a surface area of between 20 and 40 m.sup.2 /g, a mean pore radius of between 5,000 and 40,000 .ANG. and a porosity of between 40 and 90 vol %, and is definable by the following formula (in atomic proportions:X (1), Mg (1-8), Al (0.2-0.8), Cl (5-20), (Et+OEt+OR) (1-3);where: X=Hf or Zr; Et=ethyl group; OEt=ethoxy group; and OR=alkoxy group containing from 2 to 8 carbon atoms in the linear or branched alkyl portion.Such a catalyst component is obtained by preparing a solid spherical granular support by spray-drying an ethanolic solution of magnesium chloride, reacting said support with a hafnium or zirconium alkoxide or halogenalkoxide, and finally reacting the thus treated support with an alkyl aluminum chloride.

Abstract: A novel process is disclosed for polymerizing and copolymerizing alpha olefins (ethylene included) also in the presence of conjugated diolephins, and more particularly for copolymerizing ethylene with 1,3-butadiene, based on the use of a plural-component catalyst system, one of said components being a novel complex which contains titanium and magnesium. The process gives, in yields higher than 200,000 grams of polymer per g of elemental Ti, ethylene-butadiene copolymers having a distribution of monomeric units characterized by a particular novel .sup.13 C-NMR spectrum, a high apparent specific gravity and such a grit size as to impart flowability to the dry product, and a distribution in the presence of sulphur and accelerators such as to acquire a gel content (fraction insoluble in boiling xylenes) over 50%.