Abstract: This process uses such a polymerization apparatus that the inner volume of the polymerization vessel is 100 m.sup.3 or more, the ratio L/D of the length L of the straight barrel to the inner diameter D is 1.5 or more, and the uppermost stirring impeller is arranged in the range of 150 to 300 cm downwardly from the upper end position of the straight barrel of the polymerization vessel in terms of the height of the center line of the vertical width of the blade, and is characterized in that after the liquid contents of the polymerization vessel are heated to a temperature near the polymerization temperature, noncondensable gases coming into the reflux condenser are evacuated under such conditions that the flow rate of the evacuation is 10 to 100 Nm.sup.3 /hour and the evacuation time is a period equal to 20% or more of the total polymerization time, and simultaneously with or after the start of the evacuation of the noncondensable gases, the cooling by the reflux condenser is started.

Abstract: The invention relates to a process for preparing polymers by bulk polymerizing a monomer feedstock composed of styrene or styrene-like monomers and/or anionically copolymerizable comonomers employing an anionic initiator and a conventional spray-tower as reactor in the absence of a quenching solvent that fills the lower portion of the spray-tower, and the polymers so produced.

Abstract: A process for the continuous polymerization of vinyl monomers to form vinyl polymers having a molecular weight M.sub.n of from 1000 to 20,000 comprisesa. carrying out the polymerization within an annular gap from 0.5 to 10 mm in width,b. confining the annular gap on the inner surface with a rotor, andc. carrying out the polymerization at from 110.degree. to 270.degree. C.

Abstract: In the polymerization of olefins with a vapor phase fluidized bed reactor, the improvement comprises the steps of feeding seed polymer particles and the reaction is then started after feeding an organoaluminum compound on a prescribed basis, thereby avoiding the formation of sheet-like polymer in the initial period of the reaction and the lowering of the bulk density of the product polymer.

Abstract: A polymerizable composition consisting essentially of about 50 to about 90% by weight of vinylpyrrolidone monomer, about 10 to about 50% by weight of vinyl caprolactam monomer, and about 0.5 to about 7% by weight of a crosslinker, which is capable of proliferous polymerization in the absence of base at about 80.degree.-120.degree. C.

Abstract: Polyisoolefins are produced according to the invention by polymerizing isoolefins having 4 to 16 carbon atoms, optionally with conjugated diolefins having 4 to 6 carbon atoms and/or cationically polymerizable, mono- or polyunsaturated, organic compounds having 4 to 16 carbon atoms in the presence of mixtures of carbon dioxide and linear, branched and/or cyclic C.sub.4 -C.sub.8 alkanes and in the presence of catalysts at temperatures of -70.degree. C. to +20.degree. C. and pressures of 1 to 70 bar, wherein the weight ratio of carbon dioxide to alkanes is 10:90 to 90:10.The process according to the invention largely prevents the formation of fouling on the reactor walls, so ensuring better removal of heat. Moreover, in accordance with the process according to the invention, the polyisoolefins obtained may be directly chemically modified once the carbon dioxide has been removed.

Abstract: The present invention relates to a continuous process for the polymerization of an alpha-olefin having from 2 to 12 carbon atoms, which is carried out in a gas phase polymerization reactor by bringing a gaseous reaction mixture, containing the alpha-olefin to be polymerized, into contact with a catalyst system of the Ziegler-Natta type consisting of a solid catalyst comprising at least one compound of a transition metal belonging to groups IV, V or VI of the Periodic Table, of the elements, and of a cocatalyst comprising at least one organometallic compound of a metal belonging to groups II or III of the Periodic Table in which the polymerization reactor is fed with alpha-olefin at a constant rate.

Abstract: A composition of methacrilic resin which constitutes a resin possessing an outstandingly easy release from the mold of injection molding machine without defilement of the stamper and the peripheral ring of stamper holder, and therefore proves suitable material for replica of raser disk is provided. This methacrylic resin composition is characterized by having incorporated in a methyl methacrylate copolymer the three lubricant components, i.e. a higher alcohol (x), a monoglyceride of a higher fatty acid (y), and a paraffin (z), in such amounts that the individual contents of (x), (y), and (z) are in the respective ranges of 0.05 to 0.2% by weight, 0.05 to 0.2% by weight, and 0.02 to 0.15% by weight and the total content of (x), (y), and (z) is in the range of 0.2 to 0.35% by weight.

Abstract: A process for producing polyolefin with a vapor-phase fluidized-bed reactor, wherein the reaction is started after filling the reactor with particles which contain moisture and/or molecular oxygen and can form a fluidized bed in order to prevent the formation of molten resin which is liable to occur at the start of the reaction and to attain a smooth operation of the reactor.

Abstract: A process for the production of EPM or EPDM comprising contacting ethylene, propylene, and, optionally, one or more dienes, in a fluidized bed, at a temperature at or above the sticking temperature of the product resin, under polymerization conditions, with(i) a prepolymer containing a transition metal catalyst precursor with the proviso that the prepolymer is not sticky at the process temperature;(ii) a hydrocarbyl aluminum and/or a hydrocarbyl aluminum halide cocatalyst,; and, optionally,(iii) a halocarbon promoter; and, optionally,(iv) an inert particulate material having a mean particle size in the range of about 0.01 to about 150 microns wherein the particulate material is either contained in the prepolymer or is independent of the prepolymer,wherein the amount of prepolymer or the combined amount of prepolymer and inert particulate material is sufficient to essentially prevent agglomeration of the fluidized bed and the product resin.

Abstract: An advanced control method is disclosed for the polymerization of an alpha-olefin in a substantially horizontal, quench-cooled, stirred bed reactor.

Abstract: Polyvinyl chloride is prepared by suspension polymerization of a monomeric charge of vinyl chloride dispersed and suspended in an aqueous medium while agitating the suspension. An oil-soluble partially saponified polyvinyl alcohol is added to the monomeric charge as a dispersant at the start of polymerization. A water-soluble partially saponified polyvinyl alcohol and/or a hydroxypropylmethyl cellulose is continuously added as a suspending agent from the start of polymerization. The suspending agent is entirely added while the polymerization rate is in the range of 5-50%. The agitating power applied to the aqueous suspension is 50-110 kg.multidot.m/s.multidot.ton while the suspending agent is being added, and increased above 110 kg.multidot.m/s.multidot.ton after the completion of addition. The resulting polymer has a high bulk density and a sharp particle size distribution and is susceptible to extrusion.

Abstract: A continuous process is described for preparing copolymer compositions of 1,3-conjugated dienes and aromatic vinyl compounds having a weight average molecular weight of greater than about 100,000, and in one embodiment above about 900,000. The process comprises:(A) continuously introducing into a reactor, a 1,3-conjugated diene, an aromatic vinyl compound, a hydrocarbon solvent and a polymerization catalyst comprising a trimetalated 1-alkyne wherein the catalyst is obtained by reacting at a temperature of above about 70.degree. C., a 1-alkyne containing at least 4 carbon atoms, an organo metallic compound, R.degree. M and a 1,3-conjugated diene wherein the alkyne is characterized by the formulaRCH.sub.2 C.tbd.CH (II)wherein R is an alkyl group, R.degree. is a hydrocarbyl group, M is an alkali metal, the mole ratio of R.degree.

Abstract: A liquid phase, powder bed polymerization process for preparing syndiotactic polymers of vinylaromatic monomers comprising:A) continuously introducing one or more vinylaromatic monomers and one or more catalyst systems to a horizontally disposed, continuously agitated, cylindrically shaped reactor containing a particulated solid, the contents of which are maintained in an agitated state at a Froude Number in the range from 0.1 to 10, andB) continuously removing polymerized product therefrom.

Abstract: Vinyl chloride polymer is prepared by suspension polymerization of monomeric vinyl chloride or a mixture of vinyl chloride and another monomer in an aqueous medium while agitating the suspension. A first partially saponified polyvinyl alcohol having a degree of saponification of 60-80 mol % and an average degree of polymerization of 500-1,000 is added as a suspension stabilizer at the start of polymerization, and a second partially saponified polyvinyl alcohol having a degree of saponification of 75-85 mol % and an average degree of polymerization of 1,500-2,700 is added while the conversion is 30% to 60%. The agitating power is controlled to 80-120 kg.multidot.m/s.multidot.ton from the start of polymerization to a conversion of 20 to 50%, and to 130-200 kg.multidot.m/s.multidot.ton from then to the completion of polymerization.

Abstract: This invention relates to a short residence time polymerization reactor operating in periodic mode with multiple catalyst feeds and staged monomer feeds operating to minimize off specification product and optimize and control molecular weight and molecular weight distribution of the polymer produced. This invention contemplates the polymerization of olefins particularly alpha-olefins, particularly ethylene and propylene into homo, co and terpolymers.

Abstract: A support containing methylalumoxane and derivatives thereof is described which is formed by an incipient impregnation technique. The most preferred support is silica. Incipient impregnation in accordance with the invention provides a supported alumoxane, methylalumoxane, which substantially eliminates the problem of fluid bed reactor fouling when methylalumoxane is introduced into the reactor during its operation. The process comprises providing methylaluminoxane in particulate form for use as a catalytic component in the fluidized bed gas phase polymerization process.In accordance with the invention, the process comprises providing methylalumoxane activated metallocene compound in particulate form as catalysts in fluid bed gas phase.

Abstract: Polymer particles having a small particle diameter and a narrow particle diameter distribution are obtained by a continuous polymerization method which does not accompany an increase of cohering products attaching to an inner face of a reaction vessel and an air-bubble invasion and, in which stirring of a material solution for polymerization is easy. An emulsion polymerization reaction or a suspension polymerization reaction is carried out by supplying a material solution for polymerization continuously to a clearance between coaxial double cylinders, which have stretched toward a direction crossing a horizontal plane, from the end side of the cylinders, by rotating at least one of the double cylinders round the axis and thereby, causing Taylor vortices. The polymer particles thus-formed are obtained by through from the other end side of the double cylinders to the outside.

Abstract: The invention is directed toward polymerizing or copolymerizing alpha-olefins either alone or in combination with one or more other alpha-olefins in the presence of a metallocene catalyst in a gas phase reactor having a fluidized bed and a fluidizing medium such that the fluidizing medium entering the reactor comprises a gas and a liquid phase.

Abstract: An improved method for polymerizing one or more polyolefins in the presence of a transition metal catalyst in at least one gas phase fluidized bed reactor, the improvement comprises generating at least one low frequency, high pressure sound wave inside a reactor system, which wave has sufficient frequency and pressure to dislodge and/or prevent particle build-up on interior surfaces of the reactor system.

Abstract: A process for producing polymers in a gas phase reactor by continuously introducing a stream of monomer and gas into a polymerization zone while maintaining the temperature within the polymerization zone below the dew point temperature of at least one monomer present in said polymerization zone.

Abstract: A process for preparing acrylic polymers having good crater resistance by continuous polymerization in vessels having agitating means tip speed from 500 to 1200 rpm. Placement of the feed valve for charging the monomer and/or the initiator is located beneath the surface of the agitating mass.

Abstract: The present invention relates a process for uniformly mixing heterogeneous or multiphase systems comprising a continuous phase and at least a solid, dispersed phase in a pulsatile flow reactor (PUFR) as herein defined wherein the uniform mixing is carried out by actuating means for pulsing the continuous phase. The PUFR can be used in its horizontal or vertical orientation. The PUFR is useful for example to carry out the catalytic polymerization of olefins in a heterogeneous phase.

Abstract: The invention is directed toward polymerizing or copolymerizing alpha-olefins either alone or in combination with one or more other alpha-olefins in a gas phase reactor having a fluidized bed and a fluidizing medium such that the fluidizing medium entering the reactor comprises a gas and a liquid phase.

Abstract: The present invention relates to a gas phase fluidized bed reactor (1) comprising an upright tubular portion (2) having a fluidization grid (4) in the lower part thereof. According to the invention the upright tubular portion (4) is provided with an external conduit (13) which connects a lower orifice (14) which is above the fluidization grid (4) and an upper orifice (15) which is a height above the lower orifice (14). The invention also relates to a gas phase polymerization process carried out in the reactor.

Abstract: According to the present invention, in a vapor phase polymerization of olefins, there is provided an efficient polyolefin manufacturing process capable of preventing the formation of a sheet-like polymer and allowing an olefin polymerization reaction to be started stably.

Abstract: An improved method for polymerizing one or more polyolefins in the presence of a transition metal catalyst in at least one gas phase reactor having an expanded section, the improvement comprising generating a tangential flow of gas or gas-solids in the expanded section of the gas phase reactor to reduce fines entrainment into the gas cycle system and to reduce or remove solid particle build-up on one or more interior surfaces of the expanded section of the reactor.

Abstract: A process for producing a vinyl chloride-based polymer by suspension polymerizing vinyl chloride monomer or the like while circulating a reaction mixture in a polymerization vessel by a circulating pump through a circulation line led out from the polymerization vessel to extend through a heat exchanger back to the vessel, wherein the pump comprises a conical hub and an impeller comprised of a spirally shaped single blade provided on the hub, and, during polymerization, the stirring energy (A) applied to the reaction mixture by the stirrer in the polymerization vessel and the circulating energy (B) exerted to the reaction mixture by the circulating pump in the circulation line are controlled so as to satisfy the relationships(A)+(B)=from 1.5 to 4.0 kW/t (1)and(B)/[(A)+(B)]=from 0.1 to 0.6 (2)Polymer scale is prevented from being deposited on inner surfaces of the heat exchanger, circulation piping, circulating pump or the like.

Abstract: A method for reducing sheeting during polymerization of alpha-olefins in a fluidized bed employing catalysts prone to cause sheeting which comprises feeding a material carrying a static electric charge opposite to the static charge in said bed, said opposite charge of said material being generated by passing said material in contact with a surface adapted to impart said static electric charge to said material opposite the charge existing in said bed.

Abstract: A process control scheme for temporarily slowing or killing the production of polypropylene while idling the reactor using a fourth generation catalyst system containing a solid magnesium chloride supported titanium tetrachloride catalyst component containing an internal strong electron donor in combination with a silicon compound, and an organoaluminum compound (cocatalyst) is disclosed. This process entails the introduction of an amount of an external strong electron donor to the ongoing polymerization reaction. The polymerization reaction can be restarted by introducing an additional amount of the organoaluminum compound.

Abstract: The present invention relates to a process for the production of homopolymers of ethylene and copolymers of ethylene with olefins CH.sub.2 .dbd.CHR, wherein R is an alkyl or aryl radical having a number of carbon atoms of from 1 to 10, and having a density greater than 0.86 g/cm.sup.3, comprising at least one (co)polymerization step in the gas phase, in the presence of an active catalyst obtained from a titanium compound supported on a magnesium halide in active form and an Al-alkyl compound. The process is characterized in that a small amount compared with the polymer is fed to the gas-phase reactor of a polyfunctional compound having at least two groups, the same or different, capable of reacting with the alkyl aluminum compound and capable of selectively inhibiting the reactivity of the polymer particle fines compared with the average granulometric size of the polymer present in the bed of a gas-phase polymerization reactor.

Abstract: The invention is directed toward polymerizing alpha-olefins either alone or in combination with one or more other alpha-olefins utilizing a bulky ligand transition metal catalyst in a gas phase fluidized bed polymerization reactor operating in condensed mode.

Abstract: A process for producing polyolefin with a vapor-phase fluidized-bed reactor, wherein the reaction is started after filling the reactor with particles which contain moisture and/or molecular oxygen and can form a fluidized bed in order to prevent the formation of molten resin which is liable to occur at the start of the reaction and to attain a smooth operation of the reactor.

Abstract: A process for polymerizing olefins in a gas-phase fluidized-bed reactor comprising a reactor body (1), optionally surmounted by a disengagement chamber (2), in which fine particles entrained by the gas mixture leaving the top of the reactor are separated from the gas and recycled to the upper portion of the reactor body. Polymer is withdrawn from the reactor body (1) via at least two polymer outlets, at least one of which (15) is in the lower portion of the reactor body (1) and at least one of which (16) is in the upper portion of the reactor body at a position below the top of the fluidized bed. The invention includes apparatus for polymerizing olefins and the use of the apparatus.

Abstract: A process for the production of EPM or EPDM comprising contacting ethylene, propylene, and, optionally, one or more dienes, in a fluidized bed, at a temperature at or above the sticking temperature of the product resin, under polymerization conditions, with(i) a prepolymer containing a transition metal catalyst precursor with the proviso that the prepolymer is not sticky at the process temperature;(ii) a hydrocarbyl aluminum and/or a hydrocarbyl aluminum halide cocatalyst,; and, optionally,(iii) a halocarbon promoter; and, optionally,(iv) an inert particulate material having a mean particle size in the range of about 0.01 to about 150 microns wherein the particulate material is either contained in the prepolymer or is independent of the prepolymer,wherein the amount of prepolymer or the combined amount of prepolymer and inert particulate material is sufficient to essentially prevent agglomeration of the fluidized bed and the product resin.

Abstract: The invention is directed toward polymerizing or copolymerizing alpha-olefins either alone or in combination with one or more other alpha-olefins in a gas phase reactor having a fluidized bed and a fluidizing medium such that the fluidizing medium entering the reactor comprises a gas and a liquid phase.

Abstract: An improved method is proposed for the suspension polymerization of vinyl chloride monomer in an aqueous medium, by which the polyvinyl chloride resin obtained may have an increased bulk density without causing any disadvantages. The improvement can be obtained by controlling the power on the stirrer for the agitation of the polymerization mixture in such a manner that the power at the moment of the start of the polymerization reaction is 100 to 200 kgf.m/s per 1000 kg of the polymerization mixture and the power is subsequently decreased either continuously or step-wise according to a specified schedule down to 60 to 90% of the value at the start of the polymerization reaction at the moment when conversion of the monomer to polymer is 30% along with starting of the operation of the reflux condenser at a specified moment in relation to the stirrer power and the monomer conversion.

Abstract: Polymer particles having a small particle diameter and a narrow particle diameter distribution are obtained by a continuous polymerization method which does not accompany an increase of cohering products attaching to an inner face of a reaction vessel and an air-bubble invasion and, in which stirring of a material solution for polymerization is easy. An emulsion polymerization reaction or a suspension polymerization reaction is carried out by supplying a material solution for polymerization continuously to a clearance between coaxial double cylinders, which have stretched toward a direction crossing a horizontal plane, from the end side of the cylinders, by rotating at least one of the double cylinders round the axis and thereby, causing Taylor vortices. The polymer particles thus-formed are obtained by through the other end side of the double cylinders to the outside.

Abstract: A process for feeding a powder catalyst with a gas intermittently to a high-pressure fluidized bed reactor for the vapor phase polymerization of olefin, wherein the cross section of a catalyst feed pipe is reduced midway through the pipe to thereby make continual catalyst feeding possible and prevent the formation of a lump polymer.

Abstract: A process for producing a vinyl chloride-based polymer in which an aqueous suspension of a vinyl chloride-based monomeric material placed in a polymerization vessel equipped with an agitating element is subjected to suspension polymerization by introducing a polymerization initiator to the aqueous suspension at a position located inside the diameter of the agitating element being rotated. By this process it is possible to prevent totally the deposition of polymer scale on the inside wall of the polymerization vessel, particularly in the vicinity of a gas-liquid interface. Therefore, troubles arising from polymer scale formation and labor needed for removing such polymer scale are obviated, and a vinyl chloride-based polymer of high quality can be produced efficiently.

Abstract: The present invention relates to a continuous process for the polymerization of an alpha-olefin having from 2 to 12 carbon atoms, which is carried out in a gas phase polymerization reactor by bringing a gaseous reaction mixture containing the alpha-olefin to be polymerized into contact with a catalyst based on chromium oxide associated with a catalyst based on chromium oxide associated with a granular support and activated by a heat treatment in which the polymerization reactor is fed with (a) alpha-olefin and (b) catalyst at constant rates.

Abstract: There is disclosed a process for continuously and efficiently producing a styrenic polymer having a high degree of syndiotactic configuration which comprises effecting polymerization reaction by continuously introducing a styrenic monomer and a polymerization catalyst into a polymerization reactor, the inside of which has been brought into fluidized state by particles previously fed therein, which process is characterized in that the polymerization reactor temperature is controlled by vaporizing a part of the styrenic monomer which has been introduced into the polymerization reactor, while the inside of the reactor is maintained under reduced pressure. According to the above process, such problems as difficulty in polymerization reactor scale-up, adhesion of polymer to the reactor inside and polymer particle agglomerate are simultaneously solved, and thereby the industrial significance of the process is remarkably enhanced.

Abstract: Abstract of the Disclosure: Polymers of olefinically unsaturated monomers and solutions of these polymers are obtainable by a process in which the olefinically unsaturated monomers are polymerized in the presence of a free radical initiator in solution under polymerization conditions which are otherwise predetermined, in such a way that the solvent and/or a liquid part of one or more reactants of the polymerization batch are initially taken and heated to the polymerization temperature, and some or the total amount of the monomers to be polymerized is fed continuously to the agitated initially taken part of the polymerization batch via one or more feeds, with maintenance or initiation of the polymerization, in such a way that the outlet orifice of the one or more feeds is located below the surface of the initially taken liquid part of the polymerization batch.

Abstract: A process for producing a vinyl chloride polymer by polymerizing a monomer comprising vinyl chloride by suspension polymerization in a polymerization vessel on the inner wall surface of which a coating of a polymer scale preventive agent is formed, comprising the steps of applying a high-speed shearing force to a mixture comprising water, the monomer, a polymerization initiator, and (A) a dispersant comprising a partially saponified polyvinyl alcohol having a specified average degree of polymerization and a specified degree of saponification plus (B) a dispersant comprising a hydroxypropylmethylcellulose which has a specified methoxyl substitution degree, a specified hydroxypropoxyl substitution degree, and a specified viscosity and subjecting the mixture to said suspension polymerization. A vinyl chloride polymer having an average particle diameter of 200 to 600 .mu.m and a narrow particle size distribution and excellent in plasticizer take-up, etc. is provided.

Abstract: A process for preparation of a vinyl chloride polymer comprising the steps of subjecting an aqueous medium containing vinyl chloride monomer or a mixture of vinyl chloride monomer with other vinyl monomer, a polymerization initiator and a dispersant to high-speed shear agitation at a shear rate of 10.sup.4 sec.sup.-1 or above to prepare a suspended dispersion containing fine particles of the monomer(s) dispersed therein, then subjecting the suspended dispersion to low-speed shear agitation at a shear rate of from 10 to 100 sec.sup.-1, and thereafter starting suspension polymerization. Even with a decreased amount of dispersant, the process inhibits the coarsening of the polymer particles, to yield the polymer with a narrow particle diameter distribution. Deposition of scale and formation of fish-eyes are also prevented effectively.

Abstract: In a process for the microsuspension of emulsion polymerization of vinyl chloride using a polymerization apparatus equipped with an agitator the improvement where the ratio (H/D) of the effective height (H) of the apparatus to the effective inner diameter (D) of the apparatus is 4 or more.

Abstract: There is provided a suspension polymerization process for production of polymer particles having a substantially uniform size, which process comprises the steps of: (a) applying regular vibration to a flow of a monomer liquid which has a specific gravity smaller than that of an aqueous dispersion medium, (b) introducing the aqueous dispersion medium containing the droplets in a first reactor comprising a recycling means which discharges the aqueous dispersion medium from the bottom of the reactor and recycles it to the top of the reactor, (c) partially polymerizing the monomer liquid in the first reactor so that the specific gravity of the droplets does not exceed that of the aqueous dispersion medium while maintaining the suspended condition of the droplets, and (d) discharging the partially polymerized droplets together with the aqueous dispersion medium from a lower portion of the first reactor and introducing them in a second reactor, and (e) further polymerizing the partially polymerized droplets in the

Abstract: (Co)polymer particulates soluble in their corresponding (co)monomer composition, e.g., particulates of acrylic, methacrylic or styrene polymers, are produced by finely dispersing an aqueous phase including at least one polymerization initiator in an organic phase which comprises such (co)monomer composition and at least one nonsolvent for such (co)polymer which is miscible with such (co)monomer composition, and suspended emulsion polymerizing such mixed-phase polymerization recipe.

Abstract: In accordance with the present invention, there are provided cycloolefin random copolymers composed of ethylene and cycloolefin and containing substantially no polyethylene, and processes for preparing the same. Optical disc substrates prepared from the above-mentioned copolymers are excellent in transparency and also capable of minimizing the occurence of errors in reading of the discs due to quality of the substrates used therefor.

Abstract: Cyclic olefin metathesis polymerization catalyst comprising metal compounds wherein said metals consist essentially of a minor amount of a transition metal which Will initiate ring-opening metathesis polymerization of a cyclic olefin and a major amount of at least one second metal which will propagate the polymerization, wherein said catalyst is essentially devoid of pyrophoric metal compounds, e.g. metal alkyls, and preformed metal carbenes. A preferred transition metal is ruthenium. Said second metal can comprise aluminum, copper, hafnium, iron (III), iridium, manganese, molybdenum, nickel, niobium, rhenium, rhodium, tantalum, titanium, tungsten, yttrium, a Lanthanide, zinc or zirconium or a mixture thereof. Using such catalyst cyclic olefin, e.g. norbornene derivatives, can be polymerized, e.g. in an extruder, even in the presence of water.