摘要:
A process for preparing crystalline ethylene (co)polymers comprising (co)polymerizing ethylene in the presence of carried out in the presence catalyst system comprising (a) a solid catalyst component comprising Ti, Mg, halogen, ORI groups, where RI is a C1-C12 hydrocarbon group optionally containing heteroatoms, having ORI/Ti molar ratio of at least 0.5, an amount of titanium, with respect to the total weight of said solid catalyst component, higher than 4% by weight, and showing a specific pattern of the SS-NMR; and (b) an aluminum alkyl compound as a cocatalyst. The process allows to obtain in good yields ethylene polymers with narrow MWD.
摘要:
A process for preparing a catalyst component, comprising a Mg compound a Ti compound and an electron donor compound (ED) selected from alcohol, glycols, esters, ketones, amines, amides, nitrites, alkoxysilanes and aliphatic ethers as essential compounds, comprising two or more steps of reaction involving the use of at least one of said essential compounds as fresh reactant alone or in a mixture in which it constitutes the main component, said process being characterized by the fact that in the last of said one or more reaction steps the essential compound used as a fresh reactant is the ED compound.
摘要:
A class of bridged or unbridged metallocene compounds is disclosed, wherein the cyclopentadienyl ligands have two or four adjacent substituents forming one or two alkylenic cycles of from 4 to 8 carbon atoms.These metallocenes are useful as catalyst components for the polymerization of olefins, particularly for the (co)polymerization of ethylene and for the polymerization of propylene.
摘要:
Catalyst components for the polymerization of olefins CH2═CHR, wherein R is hydrogen or a hydrocarbon radical having 1-12 carbon atoms, comprising Mg, Ti, Cl, OR groups, where R is a C1-C10 alkyl group optionally containing heteroatoms, and an ether having two or more ether groups, characterized by the fact that the Mg/Ti weight ratio is lower than 3 from 2 to 6.5 the Cl/Ti weight ratio is from 1.5 to 6, the OR/Ti weight ratio is from 0.5 to 3.5 and at least 50% of the Titanium atoms are in a valence state lower than 4. The said catalyst components allow the preparation of ethylene copolymers with a low content of xylene soluble fractions.
摘要:
Process for the preparation of ethylene copolymers comprising the copolymerization of ethylene with olefins CH2═CHR, in which R is a hyrdocarbyl radical with 1-12 carbon atoms carried out in the presence of a catalyst comprising (i) a solid catalyst component comprising Mg, Ti, halogen and specific 1,3-diethers of formula (I) in which R is a C1-C10 hydrocarbon group, R1 is methyl or ethyl, optionally containing a heteroatom, and R2 is a C4-C12 linear alkyl optionally containing a heteroatom, and (ii) an organo-Al compound. The obtained copolymers are endowed with good comonomer distribution.
摘要:
Ethylene based polymers having high molecular weights can be obtained in high yields at temperatures of industrial interest, by carrying out the polymerization reaction in the presence of catalysts comprising silicon bridged metallocenes having a particular ligand system containing a heteroatom.
摘要:
Supported catalysts for the polymerization of olefins comprise the following components: (A) a porous organic support functionalised with groups having active hydrogen atoms; (B) an organo-metallic compound of aluminium containing heteroatoms selected from oxygen, nitrogen and sulphur; and (C) a compound of a transition metal selected from those of groups IVb, Vb or VIb of the Periodic Table of the Elements, containing ligands of the cyclopentadienyl type. These supported catalysts, obtainable in the form of spherical particles, can be used in the polymerization reaction of olefins either in liquid or in gas phase, thus producing polymers endowed with a controlled morphology and with a high bulk density.
摘要:
Copolymers of ethylene with comonomers selected from (a) alpha-olefins, (b) cycloolefins and/or (c) dienes, characterized by the fact that:the molar percentage of the comonomer (% .alpha.) and the density of the copolymer (D) satisfy the relation % .alpha.+150D.ltoreq.141.