Abstract: Homopolymers or copolymers obtained by a multistage process of olefins having the formula CH.sub.2 .dbd.CHR, in which R is hydrogen or R has from 1 to 10 carbon atoms and is an alkyl, cycloalkyl or aryl group, the process comprising:(A) a first stage of polymerization in which one or more of the olefins are polymerized in the presence of a titanium or vanadium catalyst;(B) a treatment stage in which the product obtained in the first stage of polymerization (A) is brought into contact with a compound capable of deactivating the catalyst present in the stage (A); and also brought into contact with a compound of a transition metal M selected from the group consisting of Ti, Zr, V, or Hf containing at least one M-.pi. bond and optionally with an alkyl-Al compound; and(C) a second stage of polymerization in which one or more of the olefins are polymerized, in one or more reactors, in the presence of the product obtained in treatment stage (B).

Abstract: Multistage process for the polymerization of one or more olefins of the formula CH.sub.2 .dbd.CHR, in which R is hydrogen or an alkyl, cycloalkyl or aryl group having from 1 to 10 carbon atoms, comprising:(A) a first stage of polymerization, in which a first olefin polymer is prepared in the presence of titanium catalyst or vanadium catalyst;(B) a treatment stage in which the catalyst used previously is deactivated and in which a metallocene compound is supported on the olefin polymer produced in stage (A); and(C) a second stage of polymerization in which one or more olefins are polymerized in the presence of the product obtained from stage (B).

Abstract: A process for preparing hyperpure propylene (co)polymers comprising polymerizing the monomer(s) in liquid monomer in the presence of a catalyst obtained by reacting an Al-trialkyl compound with a solid catalyst component comprising magnesium dihalide in active form, having supported thereon a titanium chloride or chloroalcoholate, and an ether having the general formula: ##STR1## where R and R" are the same or different and are C.sub.2-18 alkyl, C.sub.3-18 cycloalkyl, C.sub.6-18 aryl, C.sub.7-18 arylalkyl or alkylaryl radicals.

Abstract: Catalyst components for the polymerization of olefins, obtained by reacting a tetravalent titanium halide or halogen alcoholate and an electron-donor compound with a solid comprising a porous metallic oxide containing hydroxyl groups on the surface, on which is supported a magnesium dihalide or a magnesium compound which does not contain Mg-C bonds and can be transformed into a dihalide, characterized in that the quantity of Mg supported on the oxide prior to the reaction with titanium compound, and present in the catalyst component after the reaction with the Ti compound, is from 5% to 12% weight with respect to the weight of the catalyst component.

Abstract: Catalyst components for the polymerization of olefins comprising a titanium or vanadium compound supported on a porous particulate polymeric support which particles have a porosity greater than 0.3 cc/g and a pore distribution such that at least 40% of the pores have radius greater than 150 .ANG..The catalyst components are prepared by impregnating the polymeric support with a solution of the Ti or V compound and evaporating the solvent.

Abstract: Catalyst components for the polymerization of olefins comprising a titanium halide or alkoxyhalide and an electron-donor compound selected from ethers having two or more ether groups and containing at least one heteroatom selected from the group consisting of N, S, P, Si, non-ether O and halogen atoms or at least one double bond, or both at least one heteroatom and at least one double bond, supported on a magnesium halide in active form.Catalysts obtained from said catalyst components and an Al-alkyl compound, as well as catalysts obtained by the reaction of an Al-alkyl compound and an ether having the above defined characteristics with a solid catalyst component comprising a titanium halide or alkoxyhalide and an electron-donor compound having particular characteristics of extractability with Al-triethyl, supported on activated magnesium halide.

Abstract: Disclosed are catalyst components for the polymerization of olefins comprising the product of the reaction of a tetravalent titanium halide or alkoxy titanium halide and an electron-donor compound with a solid obtained by the reaction of a metal oxide containing surface hydroxyls, preferably together with chemically uncombined water, with an organometallic magnesium compound used in a quantity which does not cause reduction of the titanium in the subsequent reaction with the tetravalent titanium compound.

Abstract: Disclosed is a component for a catalyst for the polymerization of alpha-olefins to stereoregular polymers having narrow molecular weight distribution. The product is formed by the reaction of a solid catalyst-forming component comprising (1) a Ti compound having at least one Ti-halogen bond and (2) optionally, an electron-donor compound, supported on an anhydrous Mg dihalide in active form, with certain amounts of an organic compound (AH) containing at least one active hydrogen atom, in the presence of a liquid medium which is inert with respect to the Ti compound and the other components of the catalyst component, and which has a dielectric constant greater than 2 at 20.degree. C.Catalysts comprising the reaction product of the solid catalyst component prepared as above described, with an Al-alkyl compound and an electron-donor compound are also disclosed.

Abstract: Catalysts for the polymerization of olefins, particularly alpha-olefin of the formula CH.sub.2 .dbd.CHR in which R is an alkyl radical with 1-6 carbon atoms or an aryl radical, obtained by the reaction of:(a) an Al-alkyl compound;(b) an ether containing at least two ether groups which can form complexes with anhydrous magnesium dichloride, under standard conditions of reaction, in an amount less than 60 mmol per 100 g Mg dichloride; and(c) a solid catalyst component comprising an anhydrous magnesium dihalide in active form and having supported thereon a titanium compound containing at least a Ti-halogen bond and an electron-donor compound which is at least 70 mole % extractable with Al-triethyl, under standard conditions of extraction, component wherein the solid, after extraction, has a surface area of more than 20 m.sup.2 g.

Abstract: Solid catalyst components for the polymerization of olefins and modified with electron-donor compounds, comprising a titanium halide supported on a magnesium dihalide in active form and containing as an electron-donor compound a di- or other polyether having specific reactivity characteristics towards MgCl.sub.2 and TiCl.sub.4.

Abstract: Thermally stable olefin polymers are obtained by addition, before or during polymerization, or after polymerization is substantially complete, but before quenching the catalyst, which terminates the polymerization reaction, of stabilizers of the HALS type ("Hindered Amine Light Stabilizer") of monomeric or oligomeric type, containing in the molecule one or more substituted piperidyl groups having formula: ##STR1## wherein R1 are the same or different from each other and are C.sub.1 -C.sub.4 alkyl radicals, tetramethylpiperidyl radicals, or the alkyl radicals, together with the piperidyl carbon atom to which they are bonded, form a C.sub.5 -C.sub.9 cycloalkyl radical; R.sub.2 are the same or different from each other and are hydrogen, C.sub.1 -C.sub.18 alkyl radicals, C.sub.7 -C.sub.18 aralkyl radicals, or said alkyl radicals together with the piperidyl carbon atom to which they are bonded, are a C.sub.5 -C.sub.10 cycloalkyl radical; R.sub.3 are the same or different from each other and are hydrogen, C.sub.

Abstract: Catalyst components for the stereoregular polymerization of alpha-olefins, comprising a Ti halide and an electron-donor compound supported on an anhydrous magnesium dihalide and obtained by means of non-extractive treatments, with liquids having a dielectric constant at 20.degree. C. equal to or higher than 2, of compositions comprising an anhydrous Mg dihalide, the crystallites of which have an average size lower than 300 .ANG..The present invention refers to new catalyst components and the catalysts obtained therefrom for the polymerization of alpha-olefins Ch.sub.2 .dbd.CHR, wherein R is an alkyl radical with 1-4 C atoms or an aryl radical, and of mixtures of said alpha-olefins with minor amounts of ethylene.

Abstract: Catalysts for polymerizing ethylene to high yields of polyethylene having a controlled particle size are disclosed. The catalysts are prepared from new catalyst-forming components which are the reaction products of solid halogenated titanium compounds, Grignard compounds and halogenating agents. Said components, on mixing with organometallic compounds of metals belonging to Groups I-III of the Mendelyeev Periodic Table result in the catalysts capable of polymerizing ethylene to polyethylene having a controlled particle size.