摘要:
The present invention relates to a solid catalyst component for the polymerization of olefins CH.sub.2 .dbd.CHR in which R is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms, comprising a titanium compound, having at least a Ti-halogen bond and an electron donor compound supported on a Mg halide, in which said electron donor compound is selected from esters of malonic acids of formula (I): ##STR1## wherein R.sub.1 is a C.sub.5 -C.sub.20 linear or branched alkyl, a C.sub.5 -C.sub.20 cycloalkyl, a C.sub.7 -C.sub.20 arylalkyl or alkylaryl group; R.sub.2 and R.sub.3, equal to or different from each other, are C.sub.1 -C.sub.3 alkyl, cycloalkyl. Said catalyst components when used in the polymerization of olefins, and in particular of propylene, are capable to give high yields and polymers having high insolubility in xylene.
摘要:
Elastomeric ethylene/propylene or ethylene/propylene/-polyene copolymers containing small amounts of one or more .alpha.-olefins are prepared by a slurry process wherein the polymerization reaction is carried out in a mixture of liquid propylene and alpha-olefin. Problems due to fouling phenomena in the reactor are avoided.
摘要:
The present invention relates to components of catalysts for the polymerization of olefins comprising the product that can be obtained by bringing a compound of a transition metal M, containing at least one M--.pi. bond, into contact with an olefinic prepolymer obtained by polymerization of one or more olefins with a coordination catalyst comprising a compound of Ti or V supported on a magnesium halide.
摘要:
Multistage process for the polymerization of olefins CH.sub.2 .dbd.CHR, where R is hydrogen or an alkyl, cycloalkyl or aryl radical with 1-10 carbon atoms, comprising two stages of polymerization. In a first stage, in the presence of a titanium or a vanadium catalyst and working in one or more reactors, an olefinic polymer with particular values of porosity is prepared; in a second stage, in the presence of the said porous polymer and a metallocene compound and/or their reaction products, one or more olefins, that are equal to or different from those polymerized in the first stage, are polymerized in one or more reactors.
摘要:
Novel crystalline copolymers of propylene with minor proportions of ethylene and/or alpha-olefins, endowed with very good mechanical properties, a low melting point and a limited solubility in xylene at 25.degree. C., and the process for preparing them by means of the polymerization of mixtures of propylene with ethylene and/or alpha-olefins of suitable composition, by using catalysts obtained from stereorigid and chiral compounds of zirconium, and methylalumoxanic compounds.
摘要:
New metallocene ligand systems and catalysts/catalyst precursors are described where the ligand system contains at least one open-pentadienyl ligand characterized by an acyclic six .pi. electron delocalized, five atomic center structure. The open pentadienyl ligand is bonded to either another pentadienyl ligand or a Cp ligand by a bridging group. The metal is from group 3-5 or the Lanthanides. These metallocene catalysts/catalyst precursors optionally in combination with co-catalysts can be used to generate a wide variety of different polymer types including HDPE, LLDPE, LHDPE, ethylene/propylene elastomers, tactiospecific C3+ .alpha.-olefins, intimate mixture thereof and the like.
摘要:
A process is disclosed for preparing bis-cyclopentadienyl compounds bridged by a single carbon atom by reacting a carbonyl compound with a cyclopentadienyl compound in the presence of a base and of an oxygen-containing solvent having an atomic ratio carbon/oxygen not higher than 3. The compounds obtainable in high yields with this simple single-step process can be used to prepare ansa-metallocenes which are active as catalyst components in the polymerization of olefins.
摘要:
The present invention relates to components of catalysts for the polymerization of olefins comprising a metallocene compound and a magnesium halide which have particular values of porosity and surface area. In particular the components of the invention have surface area (BET) greater than about 50 m.sup.2 /g, porosity (BET) greater than about 0.15 cm.sup.3 /g and porosity (Hg) greater than 0.3 cm.sup.3 /g, with the proviso that when the surface area is less than about 150 m.sup.2 /g, the porosity (Hg) is less than about 1.5 cm.sup.3 /g. The components of the invention are particularly suitable for the preparation of catalysts for the gas-phase polymerization of .alpha.-olefins.
摘要:
Multi-layer heat-shrinkable films in which at least one layer (A) is based on a polyolefin composition comprising a propylene copolymer and having particular crystallinity characteristics, and at least one layer (B) comprises a linear compolymer of ethylene with one or more .alpha.-olefins (LLDPE). The films are characterized by an optimum balance of physicomechanical properties, processability and sealability at low temperatures.
摘要:
A process for polymerizing olefins using a fluidized bed, in which the monomer entry point is located at a point above the bed height. A pre-polymerization step can be conducted using a Z/N catalyst along with an alkane diluent, and resultant liquid phase is introduced into the fluidized bed above the bed height. The process may use several reactors in series arrangement.