Abstract: A polyolefin metallocene catalyst which includes two metallocene components, a stereorigid isospecific metallocene catalyst component and a stereorigid syndiospecific metallocene catalyst component, both of which are supported upon the same support. A method of forming a catalyst system includes contacting the above catalyst with a cocatalyst or Lewis acid. A method of polymerization includes contacting an olefin of at least 3 carbon atoms with the catalyst system.

Abstract: Process for the preparation of polyethylene by the homopolymerization of ethylene or by the copolymerization of ethylene and of at least one alpha-olefinic comonomer containing from 3 to 10 carbon atoms, in two reactors for loop polymerization in liquid phase which are connected in series in the presence of a chromium catalyst, in which ethylene and the chromium catalyst are first introduced into the first reactor at a temperature of 95 to 110.degree. C. to produce an ethylene homopolymer of low molecular weight of a melt index MI.sub.2 of at least 1 g/10 minutes and in which the ethylene homopolymer thus obtained is next transferred into the second reactor to which ethylene and optionally the alpha-olefinic comonomer is added, at a temperature of 80 to 90.degree. C. to obtain an ethylene copolymer of high molecular weight.

Abstract: Bridged metallocenes of Group IVb metals provide improved results when the bridge comprises a neutral electron-donor substituent of general formulaR'" Z R"".sub.jwhereinR'" is a rigid unsaturated hydrocarbon radical between Z and the bridge, such that Z is separated from the bridge by 2 to 5 carbon atomsZ 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: The present invention is for the improvement of inter-layer bonding strength in polypropylene films through the addition of ethylene as a mini-random copolymer in an amount of no more than about 1 weight percent, more preferably no more than about 0.7 weight percent, and most preferably between about 0.3 weight percent to about 0.5 weight percent or even amounts less than about 0.2 weight percent. The invention allows the improvement of inter-layer bond strength in multi-layer films resulting specifically in improved heat seal strength. The invention encompasses both the resulting films with enhanced heat seal strength and the process for producing such films.

Abstract: The invention provides a process for making a metallocene catalyst supported on silica treated with MAO. The invention includes supporting the metallocene compound on a MAO-treated silica at a temperature of below 0.degree. C. The supported catalyst is activated with an aluminum alkyl. The catalyst may be prepolymerized in a tubular reactor prior to being introduced into the polymerization reaction zone.

Abstract: Method of improving the crystallization rate and temperature of syndiotactic polypropylene by addition of at least one of polytetrafluoroethylene, sodium 2,2-methylene-bis-(4,6,di-tert-butylphenyl)phosphate)), pimellic acid, and calcium pimallate, and compositions and products made thereby.

Abstract: The present invention relates to the improvement of metal bonding strength in polypropylene films through the addition of ethylene in a mini-random ethylene-propylene copolymer in an amount of no more than about 1 weight percent, more preferably no more than about 0.7 weight percent, and most preferably between about 0.3 weight percent and about 0.5 weight percent, or even amounts between about 0.05 weight percent and about 0.2 weight percent. The invention allows the improvement of metal bond strength in metallizable films. The invention encompasses both the resulting films with enhanced metal bond strength and the process for producing such films.

Abstract: Metallocene catalyst components having bis-fluorenyl ligands of a staggered conformation and processes for the isotactic propagation of a polymer chain from ethylenically unsaturated monomers. The catalyst components comprise bridged bis-fluorenyl metallocenes characterized by the following formula:X(F1Y.sub.a)(F1'Z.sub.b)MeQ.sub.n (1)wherein, F1 and F1' are fluorenyl groups which are interconnected by a structural bridge X to impart stereorigidity to the metallocene ligand, Me is a Group 3, 4, or 5 transition metal each Y is the same or different and is a hydrocarbyl or heterohydrocarbyl substituent at a distal position on the fluorenyl group, each Z is the same or different and is a hydrocarbyl or heterohydrocarbyl substituent at a distal position on the other fluorenyl group F1', and a and b are each independently 1 or 2.

Abstract: Process for the production of polypropylene fibers from polypropylene polymers produced by the polymerization of polypropylene in the presence of a metallocene catalyst characterized by a bridged racemic bis(indenyl) ligand substituted at the proximal position. The polypropylene contains 0.5 to 2% 2,1 insertions and has an isotacticity of at least 95% meso diads and is heated to a molten state and extruded to form a fiber preform. The preform is subjected to spinning at a spinning speed of at least 500 meters per minutes and subsequent drawing at a speed of at least 1,500 meters per minute to provide a draw ratio of at least 3 to produce a continuous polypropylene fiber. The draw speed and/or the draw ratio can be varied to produce fibers of different mechanical properties. Different polypropylene polymers produced by different metallocene catalysts can be used. Such fibers can be characterized by having an elongation at break of at least 100% and a specific toughness of at least 0.5 grams per denier.

Abstract: Silicalite to be used as catalyst in the isomerization of olefins is pretreated by passing steam thereon at a temperature of 300 to 750.degree. C. Particularly, isobutene is selectively produced by isomerization of n-butenes.

Abstract: The present invention provides a catalyst system that exhibits unprecedented catalyst efficiencies and control of desired properties in the polymer product. The catalyst system includes a new generation titanium catalyst in combination with an electron donor described by the formula: ##STR1## wherein R.sub.1 is an alkyl group containing a primary carbon atom attached to the silicon atom; R.sub.2 and R.sub.3 are alkyl or aryl groups; and R.sub.4 is an alkyl group with a primary carbon atom attached to the silicon atom; R.sub.1 and R.sub.4 are the same or different. R.sub.1 and R.sub.4 are preferably chosen from the group consisting of n-propyl, n-butyl and methyl; most preferably n-propyl and n-butyl with R.sub.1 and R.sub.4 being the same or, alternatively, most preferably, R.sub.1 is methyl and R.sub.4 is C.sub.3 or higher. The system has a catalyst efficiency of over 30 kg/g-cat.multidot.h as the Si/Ti mole ratio varies from 4-20 in the system. The system easily achieves efficiencies over 30 kg/g-cat.

Abstract: A method of forming a polyolefin catalyst component which includes chlorinating a magnesium alkoxide, solubilizing the chlorinated magnesium alkoxide into a hydrocarbon solvent utilizing an alcohol, and then precipitating a solid from the solvent by the dropwise addition of titanium tetrachloride. Two more titanation steps follow, the first with an electron donor, the second without an electron donor, to produce a catalyst having an improved yield of polymer.

Abstract: Metallocene catalysts and their preparation and use in the polymerization of olefins. Specifically, the catalysts and processes relate to polymerization of olefins in which an aluminum ionizing agent containing a triphenylcarbenium ion is utilized in preparing the catalyst. The preparation of an olefin polymerization catalyst comprising a metallocene-type catalyst and triphenylcarbenium tetrakis(pentafluorophenyl)aluminate is disclosed.

Abstract: Stereospecific catalysts and processes for the stereotactic polymerization of ethylenically unsaturated monomers, specifically C.sub.3 -C.sub.4 alpha olefins involving a molecular sieve supported metallocene catalyst comprising a stereospecific metallocene catalyst component and a co-catalyst component. The metallocene catalyst component incorporates a metallocene ligand structure having two sterically dissimilar cyclopentadienyl ring structures coordinated with the central transition metal atom. Both the metallocene catalyst component and the co-catalyst component are supported on a molecular sieve having an average effective pore size which is less than the kinetic diameter of at least one of said ring structures. This supported catalyst is contacted in a polymerization reaction zone with an ethylenically unsaturated monomer which contains 3 or more carbon atoms or which is a substituted vinyl compound under polymerization conditions to produce stereospecific polymerization of the monomer.

Abstract: The present invention is a catalyst system to produce polymer blends in a single reactor, polymer blends of isotactic polyolefins and syndiotactic polyolefins. The catalyst system is a combination of at least one metallocene catalyst and at least one conventional supported Ziegler-Natta catalyst. The multi-catalyst system is obtained by mixing the components of at least one metallocene catalyst and at least one conventional supported Ziegler-Natta catalyst. The metallocene catalyst comprises solid complx of a metallocene compound and an ionizing agent. The conventional supported Ziegler-Natta catalyst comprises an aluminum alkyl and a transition metal compound with, optionally, an electron donor.

Abstract: Metallocene catalysts and their preparation and use in the polymerization of olefins. Specifically, the catalysts and processes relate to polymerization of olefins in which an aluminum ionizing agent containing a triphenylcarbenium ion is utilized in preparing the catalyst. The preparation of an olefin polymerization catalyst comprising a metallocene-type catalyst and triphenylcarbenium tetrakis(pentafluorophenyl)aluminate is disclosed.

Abstract: The present invention relates to polypropylene fibers and nonwoven fabrics produced from spunlaid or staple fibers having improved natural bulk. Said polypropylene fibers are made of a blend of sPP and iPP.

Abstract: A process of polymerizing ethylene with a catalyst using a single metallocene catalyst comprising a bridged metallocene compound having two cyclopentadienyl rings, one substituted with a bulky group in a distal position and one substituted such that a fused ring, substituted or unsubstituted, is formed, which produces a copolymer of ethylene. The metallocene catalyst promotes simultaneous oligomerization of a fraction of ethylene to form a comonomer in situ and copolymerization of the remaining ethylene and the comonomer to form a copolymer.

Abstract: Process for the disproportionation of toluene over a nickel modified mordenite catalyst in which catalyst activity and aging quality are enhanced for carrying out the disproportionation reaction under relatively low temperature conditions with small increases of temperature as the process continues. The catalyst is loaded into a catalytic reaction zone. A preflush gas such as hydrogen is passed into the reaction zone while withdrawing the gas from the reaction zone and progressively increasing the temperature of the reaction zone to a desired level. A toluene feedstock is then passed into the reaction zone. Hydrogen is supplied with the toluene to the reaction zone, normally at a hydrogen/toluene mole ratio of 4 or less. At the conclusion of the initial transient conditions accompanying the initiation of toluene feed to the reaction zone, initial steady state conditions for disproportionation of toluene to benzene and xylene in the presence of the catalyst are established.

Abstract: The present invention provides a catalyst system that exhibits unprecedented catalyst efficiencies and control of desired properties in the polymer product. The catalyst system includes a Toho-type, new generation titanium catalyst in combination with an electron donor described by the formula: ##STR1## wherein R.sub.1 is a bulky, basic alkyl or cycloalkyl group containing at least one secondary or tertiary carbon atom; R.sub.2 and R.sub.3 are alkyl or aryl groups; and R.sub.4 is an alkyl group with a primary carbon atom attached to the silicon atom. The system has a catalyst efficiency of at least about 30 kg/g-cat.2h as the Al/Si mole ratio varies from 20-200 in the system. The system easily achieves efficiencies over 60 kg/g-cat.2h. The system also exhibits good control over the xylene solubles, melt flow and molecular weight distribution of the polymer product.