Abstract: The present techniques relate to catalyst compositions, methods, and polymers encompassing a Group 4 metallocene compound comprising bridged ?5-cyclopentadienyl-type ligands, typically in combination with a cocatalyst, and an activator. The bridged ?5-cyclopentadienyl-type ligands are connected by a cyclic substituent.

Abstract: A method of polymerizing poly(cyclic)olefin monomers encompassing (a) combining a monomer composition containing the poly(cyclic)olefin monomers, a non-olefinic chain transfer agent and an activator compound to form a mixture; (b) heating the mixture; and (c) adding a polymerization catalyst containing Ni and/or Pd. The non-olefinic chain transfer agent includes one or more compounds selected from H2, alkylsilanes, alkylalkoxysilanes, alkylgermanes, alkylalkoxygermanes, alkylstannanes, and alkylalkoxystannanes. The activator is characterized as having an active hydrogen with a pKa of at least 5. The resulting poly(cyclic)olefin polymers can be used in photoresist compositions.

Abstract: A new class of heterocyclic metallocenes, a catalytic system containing them and a process for polymerizing addition polymerizable monomers using the catalytic system are disclosed; the heterocyclic metallocenes correspond to the formula (I): YjR?iZjjMeQkPl wherein Y is a coordinating group containing a six ? electron central radical directly coordinating Me, to which are associated one or more radicals containing at least one non-carbon atom selected from B, N, O, Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb and Te; R? is a divalent bridge between the Y and Z groups; Z is a coordinating group, optionally being equal to Y; Me is a transition metal; Q is halogen or hydrocarbon substituents; P is a counterion; i is 0 or 1; j is 1-3; jj is 0-2; k is 1-3; and l is 0-2.

Abstract: The present techniques relate to catalyst compositions, methods, and polymers encompassing a Group 4 metallocene compound comprising bridged ?5-cyclopentadienyl-type ligands, typically in combination with a cocatalyst, and a activator. The bridged ?5-cyclopentadienyl-type ligands are connected by a cyclic substituent. The catalysts of the present techniques may be more effective at the incorporation of comonomers into the backbone of a polyolefin polymer.

Abstract: A titanocene compound having a carbonyl group, and a photosensitive composition whose sensitivity has been enhanced by containing this as a photopolymerization initiator, a photosensitive transfer sheet using said photosensitive composition, and a pattern forming method using said photosensitive transfer sheet are provided.

Abstract: A new class of heterocyclic metallocenes, a catalytic system containing them and a process for polymerizing addition polymerizable monomers using said catalytic system are disclosed; the heterocyclic metallocenes correspond to the formula (I): YjR?iZjjMeQkPl wherein Y is a coordinating group containing a six ? electron central radical directly coordinating Me, to which are associated one or more radicals containing at least one non-carbon atom selected from B, N, O, Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb and Te; R? is a divalent bridge between the Y and Z groups; Z is a coordinating group, optionally being equal to Y; Me is a transition metal; Q is halogen or hydrocarbon substituents; P is a counterion; i is 0 or 1; j is 1–3; jj is 0–2; k is 1–3; and l is 0–2.

Abstract: A catalyst for preparing a polyester for a toner, comprising an inorganic tin(II) compound; a polyester resin composition comprising a polyester and the catalyst; and a toner comprising the polyester resin composition. The catalyst for preparing a polyester is suitably used for a toner which is used for developing electrostatic latent images formed in electrophotography, electrostatic recording method, electrostatic printing method, and the like.

Abstract: A class of metallocene compounds is disclosed having general formula (I) wherein Y is a moiety of formula (II) wherein A, B, and D, same or different from each other, are selected from an element of the groups 14 to 16 of the Periodic Table of the Elements (new IUPAC version), with the exclusion of nitrogen and oxygen; R1, R2, R3, R4 and R5 are hydrogen or hydrocarbon groups, Z is selected from a moiety of formula (II) as described above and from a moiety of formula (III) wherein R6, R7, R8 and R9, are hydrogen or hydrocarbon groups; L is a divalent bridging group; M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements (new IUPAC version), X, same or different, is hydrogen, a halogen, a R10, OR10, OSO2CF3, OCOR10, SR10, NR102 or PR102 group, wherein the substituents R10 are hydrogen or alkyl groups; p is an integer of from 1 to 3, being equal to the oxidation state of the metal M minus 2.

Abstract: The present invention provides a method for varying the melting points and molecular weights of polyolefins by changing the structure of the catalyst used in the polymerization. The catalysts that are useful in the present invention are chiral, stereorigid metallocene catalyst of the formula R″(C5R″m)2MeQ. The catalysts include a bridge structure between the (C5R′m) groups and may contain substituents on the groups. It has been discovered that the melting points and molecular weights of the polymers produced by such catalysts are influenced by the bridge and substituents added to the (C5R′m) groups. Thus, the present invention provides a method for varying the melting points of the polymer product and a method of varying the molecular weights of the product by changing the components and structure of the metallocene catalysts. The present invention also provides a process for polymerizing olefins in which the melting points and/or molecular weights of the product may be controlled.

Abstract: A process for preparing conjugated diene polymers by polymerizing conjugated diene monomers in the presence of a catalyst composition that is formed by combining an iron-containing compound, a hydrogen phosphite, and an organoaluminum compound.

Abstract: A catalyst for the polymerization of vinylaromatic monomers, and particularly styrene, with a high yield and a high syndiotacticity index, comprises the product consisting of the following two components in contact with each other: A) an &eegr;5-cyclopentadienyl complex of titanium; B) an organo-oxygenated compound of aluminum; and contains a sufficient amount of at least one carboxylated product having the following general formula: R—COO—G  (I) wherein R—COO is a carboxylic group comprising the organic radical R having from 1 to 30 carbon atoms, and G represents a hydrogen atom, an aliphatic or aromatic hydrocarbon group having from 1 to 20 carbon atoms or a metal atom, possibly substituted, linked to said carboxylic group.

Abstract: A very effective catalyst system for olefin polymerization comprises a cocatalyst, preferably an aluminoxane, and a metallocene of the formula I ##STR1## in which, preferably, M.sup.1 is Zr or Hf, R.sup.1 and R.sup.2 are halogen or alkyl, R.sup.3 is alkyl, R.sup.4 to R.sup.10 are alkyl or hydrogen and R.sup.11 is a (substituted) alkylene or heteroatom bridge.

Abstract: An catalyst composition for preparing high-syndiotacticity polystyrene polymers which comprises: (a) a titanium complex represented by the following formula of TiR'.sub.1 R'.sub.2 R'.sub.3 R'.sub.4 or TiR'.sub.1 R'.sub.2 R'.sub.3, wherein R'.sub.1, R'.sub.2, R'.sub.3, and R'.sub.4 are, independently, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a hydrogen atom, or a halogen atom; (b) a cyclopentadienyl complex of silicon (Si), germanium (Ge), or tin (Sn) represented by the following formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.

Abstract: Process for the preparation of crystalline vinylaromatic polymers with a high degree of syndiotacticity which comprises polymerizing vinylaromatic monomers in the presence of a catalytic system essentially consisting of:a) a complex of titanium selected from those having the general formula:(CpR.sub.1 R.sub.2 R.sub.3 R.sub.4 R.sub.5)TiX.sub.3 (I)wherein the groups R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 represent a hydrogen atom or C.sub.1 -C.sub.10 alkyl groups;X represents a hydrogen atom, a halogen such as chlorine, a C.sub.1 -C.sub.10 alkyl or oxyalkyl radical or a C.sub.6 -C.sub.12 oxyaryl radical;b) an alkylaluminoxane; andc) an organic derivative of tin;characterized in that the alkylaluminoxane is methylaluminoxane (MAO) treated at 20.degree.-80.degree. C. under vacuum for 1-100 hours and the organic derivative of tin is tin tetraphenyl.

Abstract: A catalyst component for producing polyolefin, a catalyst for producing polyolefin using the catalyst component, and a process for producing polyolefin in the presence of the catalyst. The catalyst component comprises a metallocene compound represented by formula (1): ##STR1## All the symbols in formula (1) are defined in the description.

Abstract: A highly effective catalyst system for the polymerization of olefins comprises a cocatalyst, preferably an aluminoxane, and a metallocene of the formula I ##STR1## where M.sup.1 =Zr or Hf, R.sup.1 and R.sup.2 =(C.sub.1 -C.sub.3)-alkyl or chlorine, R.sup.3, with the proviso that at least one of the radicals R.sup.3 is not hydrogen, =hydrogen, F, Cl, --OR.sup.7, --NR.sup.7 R.sup.8, --P(O)R.sup.7 R.sup.8, --P(OR.sup.7).sub.2 or SR.sup.7, R.sup.

Abstract: A process for polymerizing C.sub.2 -C.sub.10 -alk-1-enes in the presence of a metallocene complex of the formula I ##STR1## where the substituent groups have the meanings described in the specification.

Abstract: Process for the preparation of crystalline vinylaromatic polymers with a predominantly syndiotactic structure which comprises polymerizing vinylaromatic monomers, alone or mixed with at least one other monomer, in the presence of a catalytic system essentially consisting of:a) a complex of titanium or zirconium selected from those having general formula:MR.sub.1 R.sub.2 R.sub.3 R.sub.4, A.sub.1 MR.sub.1 R.sub.2 R.sub.3, A.sub.1 A.sub.2 MR.sub.1 R.sub.2 (I)b) a co-catalyst selected from an alkylalumoxane and a compound of boron having formula (II):BX.sub.1 X.sub.2 X.sub.3 (II)or one of its salts;c) a derivative of tin having general formula:SnR.sub.5 R.sub.6 R.sub.7 R.sub.

Abstract: A process for the preparation of an olefin polymer by polymerization or copolymerization of an olefin of the formula R.sup.a --CH.dbd.CH--R.sup.b, in which R.sup.a and R.sup.b are identical or different and are a hydrogen atom or a hydrocarbon radical having 1 to 14 carbon atoms, or R.sup.a and R.sup.b, together with the atoms connecting them, can form a ring, at a temperature of from -60.degree. to 200.degree. C., at a pressure of from 0.5 to 100 bar, in solution, in suspension or in the gas phase, in the presence of a catalyst formed from a metallocene in the meso-form or a meso:rac mixture, with meso:rac>1:99, as transition-metal compound and a cocatalyst, wherein the metallocene is a compound of the formula I, ##STR1## in which M.sup.1 is Zr or Hf, R.sup.1 and R.sup.2 are identical or different and are methyl or chlorine, R.sup.3 and R.sup.6 are identical or different and are methyl, isopropyl, phenyl, ethyl or trifluoromethyl, R.sup.4 and R.sup.5 are hydrogen or as defined for R.sup.3 and R.sup.

Abstract: An catalyst composition for preparing high-syndiotacticity polystyrene polymers which comprises: (a) a titanium complex represented by the following formula of TiR'.sub.1 R'.sub.2 R'.sub.3 R'.sub.4 or TiR'.sub.1 R'.sub.2 R'.sub.3, wherein R'.sub.1, R'.sub.2, R'.sub.3, and R'.sub.4 are, independently, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a hydrogen atom, or a halogen atom; (b) a cyclopentadienyl complex of silicon (Si), germanium (Ge), or tin (Sn) represented by the following formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, and R.sub.

Abstract: Group IVB metal metallocenes of bis(1-methyl fluorenyl) diphenyl silane and bis(1-methyl fluorenyl) dimethyl tin are disclosed, plus their use in the production of polyolefins, including isotactic polypropylene.

Abstract: Group IVB metal metallocenes of bis(1-methyl fluorenyl) diphenyl silane and bis(1-methyl fluorenyl) dimethyl tin are disclosed, plus their use in the production of polyolefins, including isotactic polypropylene.

Abstract: There is disclosed a process for producing a syndiotactic polystyrene (SPS) which comprises polymerizing a styrenic monomer having a content of indene-based compounds of at most 50 ppm by bringing a polymerization catalyst into contact with the above styrenic monomer, which catalyst preferably comprises an (A) transition metal compound (e.g. Ti compound) and (B) an (a) compound capable of reacting with the above transition metal compound (component (A)) to form an ionic complex (e.g. DMAB) or a (b) oxygen atom-containing compound (e.g. MAO), and optionally a (C) alkyl group-containing metallic compound (e.g. TIBA). By virtue of using the above styrenic monomer, the process enables to minimize the amount of the residual metals in the resultant styrenic polymer without deterioration of the catalytic activity, simplify the process and thereby curtail the production cost of SPS.

Abstract: Disclosed is a novel transition metal compound represented by the following formula: ##STR1## wherein M is a transition metal, X is halogen or the like, R.sup.1 is a hydrocarbon group or the like, R.sup.2 is an aryl group substituted with a halogenated hydrocarbon group, and Y is a divalent silicon-containing group or the like.Also disclosed are an olefin polymerization catalyst component comprising the transition metal compound, an olefin polymerization catalyst comprising the olefin polymerization catalyst component, and a process for olefin polymerization using the olefin polymerization catalyst.An olefin polymerization catalyst component having high polymerization activity can be formed from the transition metal compound. By the use of the olefin polymerization catalyst or the process for olefin polymerization, polyolefins having a high melting point and a high molecular weight can be prepared with high polymerization activity.

Abstract: The invention relates to a metallocene compound of the formula I ##STR1## where the two indenyl ligands have substitution patterns different from one another. The metallocene compound can be used as catalyst component for olefin polymerization.

Abstract: Catalysts comprising (a) derivatives of mono, bi and tricyclopentadienyl coordination complexes with a transition metal and (b) an alumoxane are employed in a process of producing polyolefins of controlled molecular weight.

Abstract: The invention relates to a metallocene compound of the formula I ##STR1## where the two indenyl ligands have substitution patterns different from one another. The metallocene compound can be used as catalyst component for olefin polymerization.

Abstract: The invention relates to a metallocene compound of the formula I ##STR1## where the two indenyl ligands have substitution patterns different from one another. The metallocene compound can be used as catalyst component for olefin polymerization.

Abstract: Catalyst systems for the polymerization of C.sub.2 -C.sub.10 -alk-1-enes contain, as active components,a) a metallocene complex of the general formula I ##STR1## where M is a metal of subgroup III, IV or V of the Periodic Table of Elements or a metal of the lanthanide group,X is halogen, hydrogen, C.sub.1 -C.sub.10 -alkyl, C.sub.3 -C.sub.10 -cycloalkyl, C.sub.6 -C.sub.15 -aryl, alkylaryl of 7 to 15 carbon atoms or --OR.sup.15,R.sup.15 is C.sub.1 -C.sub.10 -alkyl, C.sub.6 -C.sub.15 -aryl, alkylaryl, arylalkyl, fluoroalkyl or fluoroaryl, each having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical,n is the valency of M minus two,R.sup.1 to R.sup.14 are each hydrogen or C.sub.1 -C.sub.10 -alkyl or are each C.sub.3 -C.sub.10 -cycloalkyl which in turn may carry C.sub.1 -C.sub.10 -alkyl as substituent, or are each C.sub.6 -C.sub.15 -aryl or arylalkyl, where two adjacent radicals together may furthermore form a cyclic group of 4 to 15 carbon atoms, or are each Si(R.sup.16).sub.

Abstract: The invention relates to the use of cyclic organometallic compounds as components in coordination catalyst systems, to corresponding coordination catalyst systems and also to processes for the preparation of polymers by coordination polymerization and of unsaturated hydrocarbons by catalyzed metathesis of alkenes and alkynes using such coordination catalyst systems.

Abstract: There are disclosed a catalyst which comprises (A) a titanium compound having one .pi. electron-based ligand (e.g. pentamethylcyclopentadienyl group) or two same .pi. electron-based lignads and (B) an ionic compound comprising a non-coordinate anion and a cation of an element typifying the group 4 elements of the Periodic Table (e.g. triphenylcarbonium tetra(pentafluorophenyl)borate; a catalyst comprising (C) an alkylating agent (e.g. triisobutylaluminum) in addition to the components (A) and (B); and a process for producing a styrenic polymer by the use of any of the aforesaid catalysts. By using the aforementioned catalyst and process, a highly syndiotactic styrenic polymer can be efficiently produced.

Abstract: Solution and RIM polymerization of cycloolefins containing at least one norbornene moiety is carried out in the presence of a methathesis catalyst system and an activator, particularly a chlorosilane activator, to obtain faster reaction with higher conversions at lower mold temperatures. The methathesis catalyst system includes an organoammonium molybdate or tungstate catalyst and an alkylaluminum or an alkylaluminum halide cocatalyst. The chlorosilane activator is used at a level of 0.05 to 10 millimoles per mole of the cycloolefin monomers. The polymers of cycloolefins can be impact modified and/or flame-retarded.

Abstract: In the case of Ziegler catalysts based on a metallocene as the transition metal component and an aluminoxane as the activator, preactivation of the metallocene with the aluminoxane results in a considerable increase in the activity of the catalyst system. Furthermore, 1-olefin polymers of a high degree of isotacticity and having compact, spherical particles, a very narrow particle size distribution and a high bulk density are obtained by means of a catalyst system of this type.

Abstract: Syndiotactic polystyrene is produced in the presence of a catalyst comprising:(i) trimethylaluminum,(ii) at least one of the organotin compounds with general formulae:R.sub.1 R.sub.2 R.sub.3 Sn--O--SnR.sub.4 R.sub.5 R.sub.6or R.sub.1 R.sub.2 R.sub.3 Sn--OHor R.sub.1 R.sub.2 SnOor R.sub.1 Sn(O)OH;wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are the same or different C.sub.1 -C.sub.20 alkyl groups or aryl groups or alkylaryl groups,(iii) one or several derivatives of transition metals having the formula Cp.sub.n MA.sub.m-n, wherein M is a metal selected from the group of titanium, zirconium and hafnium, Cp is a cyclopentadienyl or a substituted cyclopentadienyl group; n is 0, 1 or 2; m is 4 or 3; and A is selected from the group consisting of a halogen, hydrogen, or an oxyhydrocarbyl group OR', wherein R' is a C.sub.1 -C.sub.6 linear or branched alkyl group, a substituted or non-substituted aryl group, or an arylalkyl group.

Abstract: Catalysts comprising (a) derivatives of mono, bi and tricyclopentadienyl coordination complexes with a transition metal and (b) and an alumoxane are employed in a process of producing polyolefins of controlled molecular weight.

Abstract: The catalyst systems of this invention consist of catalyst precursors which are metallocene derivatives and cocatalysts. The cocatalysts comprise mixtures of: (i) trimethylaluminum, and (ii) at least one organotin compound selected from the group consisting of those with a general formulae:R.sub.1 R.sub.2 R.sub.3 Sn--O--SnR.sub.4 R.sub.5 R.sub.6or R.sub.1 R.sub.2 R.sub.3 Sn--OHor R.sub.1 R.sub.2 SnOor R.sub.1 Sn(O)OH;wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are C.sub.1 -C.sub.20 alkyl groups.

Abstract: A process for the production of thermoset copolymers having tailored product properties such as high glass transition temperature and/or increased cross-linking, the process comprising contacting a comonomer mixture with a methathesis catalyst system obtainable by combining at least a catalyst component and an activator component, wherein the comonomer is selected from compounds according to the formulae: ##STR1##

Abstract: The invention is a supported catalyst system including an inert support material, a Group IV B transition metal component and an alumoxane component which may be employed to polymerize olefins to produce a high molecular weight polymer.

Abstract: Syndiospecific catalysts and processes for the syndiotactic propagation of a polymer chain derived from an ethylenically unsaturated monomer which contains 3 or more carbon atoms or is a substituted vinyl compound. The catalysts comprise an unbalanced metallocene cation, characterized by a cationic metallocene ligand having sterically dissimilar ring structures joined to a positively charged coordinating transition metal atom, and a stable noncoordinating counter anion for the metallocene cation. One of said ring structures is a substituted or unsubstituted cyclopentadienyl ring and the other of the ring structures is a substituted cyclopentadienyl group which is sterically different from the first cyclopentadienyl group. A structural bridge between cyclopentadienyl groups imparts stereorigidity to the catalyst. The catalyst is contacted with a C.sub.

Abstract: A syndiotactic polyolefin is obtained in a high yield by polymerization or copolymerization of an olefin of the formula R.sup.a --CH.dbd.CH--R.sup.b in the presence of a catalyst consisting of a metallocene of the formula I ##STR1## and an aluminoxane. This polyolefin has a very high syndiotactic index. At a low polymerization temperature, a polyolefin having a low average molecular weight and narrow molecular weight distribution is obtained, and at a high polymerization temperature a polymer having a high average molecular weight and a wide molecular weight distribution is obtained.Shaped articles produced from the polymers are distinguished by a high transparency, flexibility, tear strength and excellent surface gloss.

Abstract: Alpha-olefin polymers and copolymers are prepared by polymerizing the monomers in the presence of a catalyst obtained by bringing into contact:a) a compound definable by the formula: ##STR1## wherein: M is represents a metal of group 4.beta. of the periodic table of elements;each R independently represents halogen atom; a linear or branched C.sub.1 -C.sub.10 alkyl group; or an aryl group; andeach Cp independently represents the cyclopentadienyl, indenyl or fluorenyl, group, possible carrying one or more C.sub.1 -C.sub.4 alkyl substituents, which Cp groups can also be connected together by a carbon atom or alkylsilane bridge structure;b) a trialkylaluminium: ##STR2## wherein each R' independently represents a linear or branched C.sub.1 -C.sub.10 alkyl group, or an aryl group; andc) a distannoxane: ##STR3## where each R" independently reprepsent a linear or branched C.sub.1 -C.sub.

Abstract: A metathesis catalyst activator composition consisting essentially of an alkoxyalkylaluminum halide and a tin compound in a molar ratio of about 0.15 to 2 moles of the alkoxyalkylaluminum halide per mole of tin compound.

Abstract: A process for preparing a blend of a norbornene polymer and a vinyl polymer, the process comprising (a) injecting into a mold a reaction mixture comprising from about 30 to about 70 weight percent, based on the total monomer weight, of at least one substituted or unsubstituted norbornene monomer, from about 70 to about 30 weight percent of at least one polymerizable monomer, a metathesis catalyst system comprising a transition metal catalyst and a cocatalyst, and a free radical initiator, and (b) subjecting the reaction mixture to temperature conditions to sequentially initiate polymerization of the norbornene monomer and the vinyl monomer.

Abstract: A process for the production of thermoset polymers comprising contacting at least one monomer of the formulae: ##STR1## with a metathesis catalyst system which comprises a tungsten catalyst and a tin or silicon hydride cocatalyst.

Abstract: The invention relates to a process for the preparation of a predominantly crystalline ethylene/propylene copolymer having less than 15 mol % of propylene units, which can be carried out in liquid propylene as the suspending agent, if metallocene catalyst components of the formulae I, II or III are employed and the partial pressures of ethylene and propylene have a specific ratio. ##STR1## By means of this process, it is possible to increase the possible uses of polymerization plants which work with liquid propylene.

Abstract: The invention is a catalytic process using a Group IV B transition metal component and an alumoxane component to polymerize .alpha.-olefins to produce high crystallinity and high molecular weight poly-.alpha.-olefins.

Abstract: A novel transition-metal compound having a bis-substituted cyclopentadienyl ligand of bridged structure (I) and a novel mixture of the compound (I) with an aluminoxane (B), each useful as catalyst component(s) for stereoregular olefin polymerization are provided, which compound (I) is expressed by the formula ##STR1## wherein M is Zr or Hf; Y is Si or Ge; R.sup.1.sub.n -C.sub.5 H.sub.4-n and R.sup.1.sub.q -C.sub.5 H.sub.4-q each represent an unsubstituted or substituted cyclopentadienyl group; n and q each represent an integer of 0 to 4, but cases of n=q=0 and n=q=4 are excluded; R.sup.1 s may be same or different and each represent H, silyl or hydrocarbon radical; R.sup.2 s may be same or different and represent H or hydrocarbon radical; and Xs may be same or different and represent H, halogen or hydrocarbon radical; and which aluminoxane is expressed by the formula (II) or the formula (III) ##STR2## wherein m represents an integer of 4 to 30 and R.sup.3 represents a hydrocarbon radical.

Abstract: Olefins are polymerized in the presence of catalysts prepared from titanium compounds prepared by reacting a titanium compound such as titanium tetraisopropoxide with a compound containing at least one aliphatic hydroxyl group.

Abstract: The invention is a catalytic process using a Group IV B transition metal component and an alumoxane component to polymerize ?-olefins to produce high crystallinity and high molecular weight poly-?-olefins.

Abstract: A syndiotactic polyolefin is obtained in a high yield by polymerization or copolymerization of an olefin of the formula R.sup.a --CH.dbd.CH--R.sup.b in the presence of a catalyst consisting of a metallocene of the formula I ##STR1## and an aluminoxane. This polyolefin has a very high syndiotactic index. At a low polymerization temperature, a polyolefin having a low average molecular weight and narrow molecular weight distribution is obtained, and at a high polymerization temperature a polymer having a high average molecular weight and a wide molecular weight distribution is obtained.Shaped articles produced from the polymers are distinguished by a high transparency, flexibility, tear strength and excellent surface gloss.