Abstract: A process for producing polyethylene in a two step polymerisation process that comprises the steps of: (a) homopolymerising ethylene in the presence of a first catalyst comprising an activated chromium catalyst in a first reactor to produce a first polyethylene fraction; (b) transferring the first polyethylene fraction produced in the first reactor and at least a portion of the first catalyst to a second reactor; (c) in the second reactor homopolymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer having from 3 to 10 carbon atoms in the presence of a second catalyst under conditions which suppress residual activity in the first catalyst to produce a second polyethylene fraction; and (d) retrieving from the second reactor polyethylene comprising a blend of the first and second polyethylene fractions.

Abstract: The present invention relates to bituminous compositions used for roofing and waterproofing membranes or material comprising asymmetrical coupled polyvinyl aromatic-polydiene block copolymers having improved physical properties over broader ranges of service temperatures than those obtained from bituminous compositions prepared with symmetrical block copolymers of similar type. The asymmetry of the copolymer which is characterised by polyvinyl aromatic endblocks of at least two different molecular weights, one high and one low, ensures improved physical performance to roofing and waterproofing membranes made from such compositions.

Abstract: The present invention relates to the production of high density polyethylene homopolymers or copolymers having a broad and monomodal molecular weight distribution wherein the polymerization process is conducted in the presence of supported metallocene-alumoxane catalysts wherein the metallocene is bridged, comprises at least a hydrogenated indenyl or fluorenyl and is isolated on its support under the form of all its conformers.

Abstract: The present invention provides a lubricating oil or a lubricating oil additive, particularly suitable for a R-134a (1,1,1,2-tetrafluoroethane) or R-134 (1,1,2,2-tetrafluoroethane) refrigerant, consisting of a compound (X) that can be prepared by esterification of a polyoxyethoxylated glycerol with at least one polycarboxylic acid compound having from 2 to 20 carbon atoms, preferably from 4 to 13 carbon atoms, and at least one monocarboxylic acid compound having from 2 to 20 carbon atoms, preferably from 6 to 13 carbon atoms.

Abstract: A process for preparing a Ziegler-Natta catalyst, which process comprises: (i) mixing in a hydrocarbon solvent a dialkyl magnesium compound of general formula MgR1R2 with a chlorinating agent soluble in the hydrocarbon solvent under conditions to precipitate controlledly a magnesium dichloride derivative, wherein R1 and R2 are each independently a C1 to C10 alkyl group, and the chlorinating agent is obtainable from the reaction between an alcohol of general formula R3OH and an alkyl aluminum chloride of general formula R4nAlCl3−n, in which R3OH is a cyclic or branched C3 to C20 alcohol, each R4 is independently a C2 to C8 alkyl and n is 1 or 2; (ii) removing unwanted reducing species by washing or reaction; and (iii) titanating the magnesium dichloride derivative with a chlorinated titanium compound to produce the Ziegler-Natta catalyst.

Abstract: Pigmented powder coating products based on low melting point fluorine-based terpolymers, preferably on those made from a majority of vinylidene fluoride copolymerized with tetrafluoroethylene and hexafluoropropene, are capable of providing coatings with controllable gloss properties. The process for preparing coatings from the powders is essentially characterized by the selection of the temperature at which the desired gloss can be obtained, from low to high, without degradation of the mechanical properties.

Abstract: A process for producing high density polyethylene in the presence of a Ziegler-Natta catalyst system in two liquid full loop reactors in series, wherein in a first reactor a first polyethylene product is polymerized substantially by homopolymerization of ethylene and hydrogen, optionally with a minor degree of copolymerization of ethylene with an alpha-olefinic comonomer comprising from 3 to 8 carbon atoms, and in a second reactor serially connected to the first reactor downstream thereof a second polyethylene product is copolymerized from ethylene and an alpha-olefinic comonomer comprising from 3 to 8 carbon atoms, and a hydrogenation catalyst is introduced into the reactants downstream of the first reactor.

Abstract: A process for the preparation of polyethylene resins having a multimodal molecular weight distribution which comprises: (i) contacting ethylene monomer and a comonomer comprising an alpha-olefin having from 3 to 10 carbon atoms with a first catalyst system in a first reactor under first polymerization conditions in a slurry process to produce a first polyethylene having a first molecular weight an HLMI of not more than 0.5 g/10 min and a first density of not more than 0.

Abstract: A process for the preparation of supported metallocene-alumoxane catalysts comprising the steps of: a) reacting a metallocene with an alumoxane at a temperature comprised between 15 and 50° C., b) recovering a mixture comprising an alkylmetallocenium cation and an anionic alumoxane oligomer, c) reacting said mixture with a support, and d) recovering a supported metallocene-alumoxane catalyst as a dry solid, the reaction with the support being carried out at a temperature comprised between 85° C. and 110° C., preferably between 90 and 130° C., and their use for the polymerization or copolymerization of olefins.

Abstract: A process for preparing a supported chromium-based catalyst for the production of high density polyethylene, by polymerising ethylene, or copolymerising ethylene and an alpha-olefinic comonomer comprising 3 to 10 carbon atoms, which comprises the steps of: a) providing an alumina-containing support; b) depositing a chromium compound on the support to form a chromium-based catalyst; c) dehydrating the chromium-based catalyst to remove physically adsorbed water by heating the catalyst at a temperature of at least 300° C. in an atmosphere of dry, inert gas; d) titanating the chromium-based catalyst at a temperature of at least 300° C.

Abstract: The present invention relates to a supported chromium-based catalyst titanated under specific conditions and used for the homopolymerization or the copolymerization of ethylene. The polyethylene obtained with this catalyst has high shear resirance and environmental stress crack resistance, and can be used for manufacturing films with improved tear properties.

Abstract: A process for producing polyethylene having impact resistance, the process comprising polymerizing ethylene, or copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms, in the presence of a chemically reduced chromium-based catalyst containing in a support thereof from 2 to 3 wt % of titanium, based on the weight of the catalyst. The invention also provides a chromium-based catalyst for the production of polyethylene by polymerizing ethylene or copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms, the catalyst being chemically reduced and containing in a support from 2 to 3 wt % of titanium, based on the weight of the catalyst.

Abstract: A C1 symmetric metallocene compound of general formula R″(CpRn)(Cp′R″m) MQp for use as a catalyst component in the production of short sequence syndiotactic/isotactic block polyolefins, wherein Cp is a substituted cyclopentadienyl; each R is independently aryl or hydrocarbyl having 1 to 20 carbon atoms, at least position 3 of Cp is substituted with aryl, at least one other position of Cp is substituted with a non-bulky substituent, and n is an integer in the range from 2 to 4; Cp′ is substituted or unsubstituted fluorenyl; each R′ is independently hydrocarbyl having 1 to 20 carbon atoms and m is O or an integer in the range from 1 to 8; R″ is a structural bridge to impart stereorigidity between Cp and Cp′; M is a metal from Group IIIB, IVB, VB or VIB; Q is a hydrocarbyl radical having 1 to 20 carbon atoms or a halogen; and p is the valence of M minus 2.

Abstract: A process for eliminating color from vinyl aromatic/conjugated diene copolymers which process comprises treating the copolymers with a monocarboxylic acid having general formula R—COOH, where R is a hydrocarbon radical comprising 2 to 4 carbon atoms and R further comprises linear or branched aliphatic radicals, cycloaliphatic radicals, alkenic radicals, aromatic radicals or alkylaromatic radicals.

Abstract: Bridged metallocenes of Group IVb metals provide improved results when the bridge comprises a neutral electron-donor substituent of general formula R′″ZR″″j wherein R′″ is a rigid unsaturated hydrocarbon radical between Z and the bridge, such that Z is separated from the bridge by 2 to 5 carbon atoms Z is nitrogen, phosphorus, oxygen or sulphur, R″″ is H or an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl having a maximum of 15 carbon atoms, each R″″ being the same or different, j is 1 when Z=O or S and 2 when Z=N or P.

Abstract: A process is disclosed for manufacturing coupled radial block copolymers of the S-B-Li type having improved optical properties, which process utilizes coupling agents having from about 3 to about 7 epoxy groups per mole.

Abstract: A process for producing high density polyethylene suitable for blow molding and having high environmental stress cracking resistance and rigidity, comprising copolymerizing ethylene and a C.sub.3 -C.sub.10 alpha-olefinic comonomer in the presence of a chromium-based catalyst having an alumina-containing support, and an organoboron compound, wherein the atomic ratio of boron in the organoboron compound to the chromium in the chromium-based catalyst is from around 0.2 to around 0.4.

Abstract: The present invention related to a process for the treatment of vinyl aromatic/conjugated diene block copolymers. More particularly, the present invention relates to a process for the treatment of such copolymers obtained starting from a (co)polymerization-initiating stage performed by means of alkaline based catalysts (Me), deactivated in such a way that they show a termination of the alkali metal-alcoholate type (--O--Me), and treated with a cyclic anhydride of polycarboxylic acid, and optically a C.sub.2 -C.sub.4 monocarboxylic acid.

Abstract: A process for producing a crystalline silicate catalyst having a monoclinic structure, the process comprising providing a crystalline silicate of the MFI-type having a silicon/aluminum atomic ratio lower than 80; treating the crystalline silicate with steam and thereafter leaching aluminum from the crystalline silicate by contact with an aqueous solution of a leachant to provide a silicon/aluminum atomic ratio in the catalyst of at least 80 whereby the catalyst has a monoclinic structure.

Abstract: Use of a homogeneous blend of a metallocene-catalyzed medium density polyethylene (mMDPE) with low density polyethylene (LDPE) and/or a linear low density polyethylene (LLDPE), to produce blown films, this composition essentially consisting of from 0.5 to 100% by weight of MMDPE and from 0 to 99.5% by weight of LDPE and/or LLDPE.The compositions of this invention have good processability and are used to make blown films which have the good optical properties of LDPE and the good mechanical and processing properties of MDPE.