| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 23.11.1999 |
| PATENT TITLE |
Indenyl compounds and catalyst components for the polymerization of olefins |
| PATENT ABSTRACT |
The invention relates to an indenyl compound of the general formula R'Ind--M--(Cp)Q.sub.k in which the symbols have the following meanings: Ind: an indenyl group R': a substituent, other than hydrogen, to the Ind group, Cp: a cyclopentadienyl group M: a transition metal from group 3, 4, 5 or 6 of the Periodic System of Elements Q: a ligand to M and k is an integer linked to the valence of M. The invention is characterized in that the R' group is bound to the Ind group at the 2-position. The indenyl compound is a catalyst component for the polymerization of olefins. The invention also relates to polymers obtainable with such indenyl compounds. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | March 10, 1997 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED |
HH Brintzinger et al. (1995) Angew. Chem. Int. Ed. Engl, 34, 1143 (pp. 1143-1145 & ref). Whelan, T., "Polymer Technology Dictionary," Chapman & Hall, London, 1994, entry under "x-olefin" at p. 1. |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
We claim: 1. A process for polymerizing an olefin which comprises contacting at least one olefin with a 2-indenyl compound having an unsaturated aromatic six-membered ring, in the presence of a cocatalyst, under effective polymerization conditions, wherein said 2-indenyl compound is represented by the general formula R'Ind--M--(CP)--Q.sub.k ( 1) wherein Ind represents an indenyl group, R' represents a substituent, other than hydrogen, bound to the Ind group at the 2-position, Cp represents a cyclopentadienyl group, M represents a transition metal from group 4, 5, or 6 of the Periodic System of Elements, Q represents a ligand to M, and k is an integer linked to the valence of M, wherein k equals the valence of M minus two divided by the valence of Q, and wherein in said process for polymerizing an olefin, processes utilizing compounds in which the Cp-group is an indenyl group and in which either: a) the Ind- and the Cp-groups are bridged over the respective 1-positions, b) the indenyl compound is bis(2,3-dimethyl-1-indenyl)-zirconiumdichloride, or c) the indenyl compound is either ethylene-1-(3-but-3-enyl) inden-1-yl-2-((1-but-3-enyl)-inden-2-yl)-zirconiumdichloride, or ethylene-1-((3-allyldimethylsilyl) inden-1-yl)-2-((1-allyldimethylsilyl)inden-2-yl)zirconium-dichloride, are disclaimed as the process for polymerizing an olefin with a 2-indenyl compound. 2. A process according to claim 1, wherein R' is an alkyl group. 3. A process according to claim 1 wherein the Cp group is a 2-indenyl group represented by the formula: R"Ind wherein R" represents a substituent other than hydrogen at the 2-position of the Ind group. 4. A process according to claim 3, wherein R" is an alkyl group. 5. A process according to claim 4, wherein said alkyl group contains 1-4 carbon atoms. 6. A process according to claim 1, wherein R' forms a bridge between the Ind group and the Cp group in formula (1). 7. A process according to claim 6, wherein said indenyl compound is represented by the formula: ##STR3## wherein R is bound at the 2-position to both 2-Ind groups, wherein R is a hydrocarbon group or a group with at least one heteroatom from group 14, 15 or 16 of the Periodic System of Elements. 8. A process according to claim 7, wherein R is selected from the group consisting of a methylidene group, an ethylidene group and a group having at least one heteroatom from group 14, 15 or 16 of the Periodic System of Elements. 9. A process according to claim 8, wherein R contains a heteroatom selected from the group consisting of silicon, nitrogen, phosphorus, oxygen and sulphur. 10. A process according to claim 8, wherein said R-group is a sulphur atom, --(CH.sub.2).sub.2 --S--(CH.sub.2).sub.2 --, an oxygen atom, (CH.sub.3).sub.2 Si.dbd., --Si(CH.sub.3).sub.2 --Si(CH.sub.3).sub.2 --, Ge(CH.sub.3).sub.2 --, (phenyl)P.dbd., or (phenyl)N.dbd.. 11. A process according to claim 8, wherein said R group is a hydrocarbon group. 12. A process according to claim 1, wherein said at least one olefin is selected from the group consisting of ethylene, .alpha.-olefin, internal olefin, and diolefin. 13. A process according to claim 1, wherein said at least one olefin is selected from the group consisting of ethylene, propylene, butene, pentene, heptene, and octene. 14. A process according to claim 1, wherein said polymerization yields a polymer based on at least one of olefin selected from the group consisting ethylene and propylene. 15. A process according to claim 13, wherein said polymerization yields a rubbery polymer based on ethylene, propylene and, optionally, a diene. 16. A process for polymerizing at least one olefin which comprises contacting at least one olefin with a 2,2'-bridged bisindenyl Group 4, 5, or 6 metallocene compound, in the presence of a cocatalyst, under effective polymerization conditions. 17. A process for polymerizing at least one olefin which comprises contacting at least one olefin with a 2,2'-bridged bisindenyl Group 3 or lanthanide metallocene compound under effective polymerization conditions. 18. A process for polymerizing an olefin which comprises contacting at least one olefin with a 2-indenyl compound, optionally in the presence of a cocatalyst, under effective polymerization conditions, wherein said 2-indenyl compound is represented by the general formula R'Ind--M--(Cp)--Q.sub.k ( 1) wherein Ind represents an indenyl group, R' represents a substituent, other than hydrogen, bound to the Ind group at the 2-position, Cp represents a cyclopentadienyl group, M represents a transition metal from group 3 and the lanthanides of the Periodic System of Elements, Q represents a ligand to M, and k is an integer linked to the valence of M, wherein k equals the valence of M minus two divided by the valence of Q. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION The invention relates to indenyl compounds that can be used as catalyst component for the polymerisation of olefins. The invention also relates to a process for the polymerisation of olefins and to a polyolefin. Indenyl compounds are known as catalyst component for olefin polymerisation. The catalysts obtained using indenyl compounds exhibit a high polymerisation activity. See for example DE-A-3,840,772. The known indenyl compounds have the general formula: R'Ind--M--(Cp)Q.sub.k (1) in which the symbols have the following meanings: Ind an indenyl group, R' a substituent, other than hydrogen, to the Ind group, Cp a cyclopentadienyl group, M a transition metal from group 3, 4, 5 or 6 of the Periodic System of Elements, Q a ligand to M. The Periodic System of Elements is understood to be the new IUPAC version as printed on the inside cover of the Handbook of Chemistry and Physics, 70th edition, CRC Press, 1989-1990. In formula (1), k is an integer linked to the valence of M in the following manner: k equals the valence of M minus two divided by the valence of the Q group. The Ind group and the Cp group are both bound to the metal M. SUMMARY AND OBJECTS OF THE INVENTION The said compounds are regarded as belonging to the metallocene compounds (metallocenes). One of the aims of the invention is to provide new indenyl compounds with the general formula (1). Another aim is to provide an indenyl compound having favourable properties as a catalyst component in olefin polymerisation. The invention concerns an indenyl compound having the general formula (1), characterized in that the substituent R' in formula (1) is bound to the Ind group at the 2-position. Here and hereinafter such a compound will be referred to as 2-indenyl compound (2-Ind). In the known indenyl compounds the substituent R' is bound to the 1-position of the indenyl ring; the known indenyl compounds are therefore 1-indenyl compounds. DETAILED DESCRIPTION OF THE INVENTION In general and in this description, the substituent locants of the indenyl ring are numbered in accordance with the IUPAC Nomenclature of Organic Chemistry, 1979, rule A 21.1. The numbering of the substituent locants for indene is given below. This numbering is analogous in the case of an Indenyl ring: ##STR1## According to the invention 2-indenyl compounds were found to exhibit an activity different from that of the known 1-indenyl compounds in olefin polymerisation. In the solution polymerisation of olefins, in particular in the polymerisation to polyethylene, such compounds exhibit higher activity. In the production of ethylene-.alpha.-alkene-(third monomer) rubbers (the so-called EA(D)M rubbers) they lead to products that differ from the usual products obtained with metallocenes, among other things to products with a very low content of crystalline material. In the compounds according to the invention the Cp group in formula (1) is a cyclopentadienyl group or a derivative thereof, like for example a fluorenyl group or an indenyl group, all of them whether or not substituted. From EP-A-485,821 and EP-A-485,823 bisindenyl-metallocenes are known having a bridge coupled to the 1-positions of the indenylgroups. Such metallocenes are expressly excluded. In EP-A-500,944 an halogenated metallocene, bis(2,3-dimethyl-1-indenyl)zirconiumdichloride is mentioned. This metallocene is also expressly excluded from the 2-indenyl compounds of the invention. EP-A-372,414 indicates two specific halogenated, bridged metallocenes. The chemical names of the two metallocenes (of formula II-1 and II-2 on page 5 of said EP-A) are: ethylene-1-(3-but-3-enyl)inden-1-yl)-2-((1-but-3-enyl)-inden-2-yl)zirconium dichloride, and ethylene-1-((3-allyldimethylsilyl)-inden-1-yl)-2-((1-allyldimethylsilyl)-in den-2-yl)zirconiumdichloride. Also these two bisindenyl compounds are expressly excluded from the 2-indenyls of the invention. The above mentioned disclaimers relative to the prior art are justified as neither in the texts nor in examples thereof it is disclosed or suggested that these metallocenes, in which the above indicated Cp-group is an indenylgroup, form part of the generic group of 2-indenyl-metallocenes, having the properties as described hereinabove. Besides that the R' group is present in the indenyl compound at the 2-position, the indenyl group (the Ind group in formula 1) may optionally also be substituted at other positions. The Cp group may also be substituted. As R' group, a hydrocarbon group (like alkyl, aralkyl, aryl) or a group with at least one heteroatom from group 14, 15 or 16 of the Periodic System of Elements may be used. Examples of such a heteroatom containing group are: alkylsulphides (like MeS-, PhS-, n-butyl-S-), amines (like Me.sub.2 N-, n-butyl-N-), Si or B containing groups (like Me.sub.3 Si- or Et.sub.2 B-) or P-containing groups (like Me.sub.2 P- or Ph.sub.2 P-). Hydrogenated forms of 2-indenyl compounds also fall within the spirit of the invention. As a substituent at a position other than the 2-position of the Ind group or the Cp group such groups as indicated above for R' may also be used. According to the invention, when R' is a hydrocarbon group, R' is preferably an alkyl group, more in particular an alkyl group with 1-4 carbon atoms. The Q group in the compounds according to the invention comprises one or more uni- or polyvalent anionic ligands to the transition metal. As examples of such ligands, which may be the same or different, the following can be mentioned: a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a group with a heteroatom chosen from group 14, 15 or 16 of the Periodic System of Elements, such as an amine group or amide group, an S compound, such as sulphide, sulphite, sulphate, thiol, sulphinate, a P compound, such as phosphine, phosphite, phosphate. The skilled in the art can determine the suitability of these and other ligands through simple experimenting. The number of Q groups in the 2-indenyl compound according to the invention (index k in formula (1)) is determined by the valence of the transition metal M and the valence of the Q groups itself. The transition metal in the 2-indenyl compound (the M group) is chosen from groups 3 through 6 of the Periodic System of Elements. The transition metal is preferably chosen from the group Ti, Zr, Hf, V, Nb, Cr, Ta, Sm and Mo. Zr, Hf or Ti are greatly preferred. Another preferred embodiment of the invention is formed by compounds in which the Cp group is a 2-indenyl group with the formula: R"Ind (3) where R" is a substituent other than hydrogen at the 2-position of the Ind group. As R" group, a hydrocarbon group (like alkyl, aryl, aralkyl) or a group with at least one heteroatom from group 14, 15 or 16 of the Periodic System of Elements may be used. Such a substituent can be the same as or different from the substituent used as R'. The R" group, when being a hydrocarbon group, is preferably an alkyl group, in particular an alkyl group with 1-4 carbon atoms. When used as, for example, catalyst in the solution polymerisation of ethylene at reaction temperatures of at least 130.degree. C. these compounds have a high catalytic activity, and in the production of ethylene-.alpha.-alkene-(third monomer) rubbers they lead to products with a very low content of crystalline material. In another preferred embodiment of the invention, the indenyl group of formula (1) is a group in which is R' is linked to the Cp group in formula (1). These compounds, in which R1 forms a bridge between the 2-position of the Ind group and the Cp group in formula (1), are referred to as bridged 2-indenyl compounds according to the invention. The other compounds according to formula (1), without the bridge between the 2-indenyl group and the Cp group, are referred to as unbridged 2-indenyl compounds. In particular, in a bridged 2-indenyl compound the Cp group in formula (1) is a 2-indenyl group as well, which is bound to the R' group at the 2-position. Such compounds according to the invention are referred to as bridged bis(2-indenyl) compounds; in such a case the R' group forms a bridge between two 2-indenyl groups, hence the term bridged bis(2-indenyl) compound. The formula of these bridged bis(2-indenyl) compounds according to the invention may be represented as follows: ##STR2## where R is a group derived from R'. In a bridged bis(2-indenyl) compound according to the invention, R can be a hydrocarbon group (like an alkenyl group, an arylalkenyl group) or a group with at least one heteroatom from group 14, 15 or 16 of the Periodic System of Elements. Preferably the choice of the R group, when being a hydrocarbon group, is between a methylidene group and an ethylidene group. If R contains a heteroatom, this heteroatom is preferably chosen from the group comprising silicon, nitrogen, phosphorus, oxygen or sulphur. Examples from R-groups containing a heteroatom are: sulphur or --(CH.sub.2).sub.2 --S--(CH.sub.2).sub.2 --, oxygen, Me.sub.2 Si.dbd., --SiMe.sub.2 --SiMe.sub.2 --, (CH.sub.3).sub.2 GE.dbd., PhP.dbd. or PhN.dbd.. The hydrocarbon groups in these R-groups containing a heteroatom may be varied and can be an alkyl, aryl or aralkylgroup. With such bridged bis(2-indenyl) compounds as catalyst component, good results are obtained in the solution polymerisation of ethylene and in the synthesis of EA(D)M rubbers. The 2-indenyl compounds according to the invention can be prepared via different synthesis routes, consisting of synthesis steps known as such. They can for example be prepared by converting a 2-indene compound into its anion. Compounds that are suitable for converting the 2-indene compound into the anion are organometallic compounds, amines, metal hydrides and alkaline or alkaline earth metals. Organolithium, organomagnesium and organosodium compounds can for example be used for this purpose, but also sodium or calcium. In particular organolithium compounds are highly suitable, preferably methyl-lithium or n-butyl-lithium. The elucidation of the further synthesis steps will be based on the use of a lithium anion, but the invention is by no means limited to this. In the case of non-bridged ligands the conversion takes place via reaction with 1 equivalent organolithium compound to obtain the mono-anion, and in the case of bridged ligands via reaction with 2 equivalents organolithium compound to obtain the di-anion. The 2-indenyl anion thus prepared is subsequently converted into the 2-indenyl compound of the invention by trans-metalation with a compound of a transition metal from groups 3, 4, 5 or 6 of the Periodic System of Elements (M in formula (1)). See for example EP-A-420,436, EP-A-427,697. The process described in NL-A-91,011,502 is particularly suitable. Examples of transition metal compounds that are suitable for trans-metalation are TiCl.sub.4, ZrCl.sub.4, HfCl.sub.4, Zr(OBu).sub.4 and Zr(OBu).sub.2 Cl.sub.2. The trans-metalation is preferably carried out as in NL-A-91,011,502, in a solvent or in a combination of solvents that weakly coordinate to transition metals from the groups 3, 4, 5 or 6 with at most 1 mole equivalent, relative to the transition metal compound started from, of a Lewis base of which the conjugated acid has a pK.sub.a greater than -2.5. Examples of suitable solvents/dispersants (pK.sub.a of conjugated acid .ltoreq.-2.5) are ethoxyethane, dimethoxyethane, isopropoxyisopropane, n-propoxy-n-propane, methoxybenzene, methoxymethane, n-butoxy-n-butane, ethoxy-n-butane and dioxane. Part of the reaction medium may consist of hydrocarbons (hexane and the like). In the said trans-metalation LiCl is formed besides the metallocene. This usually precipitates in the dispersants used. If the metallocene precipitates too, the combination of metallocene and LiCl as such can be used with a co-catalyst (aluminium compound or cation-generating agent) for the polymerisation of olefins. The LiCl may also be separated from the metallocene, for example by dissolving the metallocene in dichloromethane and filtering LiCl off. If the metallocene dissolves in the solvent used in the synthesis, the LiCl can be separated at once by filtration. The 2-indene compounds mentioned heretofore as compounds started from can be formed from commercially available compounds, via synthesis routes consisting of several known reaction steps. The synthesis route is chosen on the basis of the 2-indenyl compound desired. The unbridged 2-indenyl compounds, for example, can be prepared from 2-indanones, which are commercially available, via reaction with an alkyl magnesium halide, followed by dehydration. The synthesis of the bridged 2-indenyl compounds strongly depends on the 2-indenyl compound desired. Various synthesis routes are described in the examples given hereafter. The 2-indenyl compounds according to the invention can be used, via methods known for metallocenes, as catalyst component for the polymerisation of one or more olefins. Particularly the olefin(s) is/are chosen from the group comprising .alpha.-olefins, internal olefins and diolefins. Mixtures of these can also be used. The invention relates in particular to a process for the polymerisation of (an) .alpha.-olefin(s). The olefin or .alpha.-olefin(s) is/are preferably chosen from the group comprising ethylene, propylene, butene, pentene, heptene and octene, while mixtures can also be used. More preferably, ethylene and/or propylene is/are used as the olefin. The use of such olefins leads to the formation of crystalline polyethylene homopolymers and copolymers of both low and high density (HDPE, LDPE, LLDPE, etc.), and polypropylene homopolymers and copolymers (PP and EMPP). The monomers needed fur such products and the processes to be used are known to the skilled in the art. The process according to the invention is also eminently suitable for the preparation of amorphous or rubbery copolymers based on ethylene and another .alpha.-olefin. Propylene is preferably used as the other .alpha.-olefin, so that EPM rubber is formed. It is also quite possible to use a diene besides ethylene and the other .alpha.-olefin, so that a so-called EADM rubber is formed, in particular EPDM (ethylene propylene diene rubber). The 2-indenyl compounds according to the invention can be used as catalyst, both supported and unsupported. The supported catalysts are mainly used in gas-phase and slurry processes. The support is any support known as support for metallocene catalysts, for example SiO.sub.2 or Al.sub.2 O.sub.3. The 2-indenyl compounds according to the invention are particularly suitable for an unsupported catalyst in solution polymerisation processes. In solution polymerisation the known solvents may be used. Preferably aliphatic hydrocarbons, such as hexane and heptane, and mixtures of aliphatic hydrocarbons are used. If an aliphatic hydrocarbon is used as solvent, the solvent may still contain small amounts of aromatic hydrocarbon, for example toluene. If methylaluminoxane (MAO) is used as co-catalyst, for example, toluene may serve as solvent to make it possible to meter the MAO to the polymerisation reactor in solution. In the solution polymerisation of either ethylene or ethylene with other .alpha.-olefins and/or non-conjugated dienes at comonomer contents of up to 25%, reactor temperatures of at least 130.degree. C. are used, in order to keep the polymer produced in solution. At weight percentages of incorporated comonomer of from 30 to 80% the catalysts according to the invention yield such homogeneous products that the polymerisation can be carried out at much lower reactor temperatures (.gtoreq.30.degree. C.) without the polymer formed precipitating from the solution. Suitable other .alpha.-olefins are for example propylene, butene, hexene and octene. Polymerisation of the olefin can take place in a known manner, in the gas phase as well as in a liquid reaction medium. In the latter case both solution polymerisation and suspension polymerisation are options. The process according to the invention will hereafter be elucidated with reference to the EP(D)M preparation known per se, which is representative of the olefin polymerisations meant here. For the preparation of other polymers based on an olefin the reader is emphatically referred to the multitude of publications on this subject. As suitable .alpha.-olefins that may be used as monomer besides ethylene in the preparation of an EA(D)M polymer, the following may be mentioned: propylene, butene-1, pentene-1, hexene-1, octene-1 or the branched isomers thereof, for example 4-methylpentene-1, and in addition styrene, .alpha.-methylstyrene. Mixtures of these alkenes may also be used, propylene and/or butene-1 being preferred. As diene to be used in such an amorphous copolymer a polyunsaturated compound is started from, which may be used and serves to incorporate unsaturation in the polymer; it contains at least two C.dbd.C bonds and may be aliphatic or alicyclic. Aliphatic polyunsaturated compounds generally contain from 3 to 20 carbon atoms, the double bonds being conjugated or, preferably, unconjugated. Examples hereof are: 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, piperylene, mycrene, allene, 1,2-butadiene, 1,4,9-decatrienes, 1,4-hexadiene, 1,5-hexadiene and 4-methyl-1,4-hexadiene. Alicyclic polyunsaturated compounds, which may or may not contain a bridgeing group, may be either monocyclic or polycyclic. Examples of such compounds are norbornadiene and its alkyl derivatives; the alkylidene norbornenes, in particular the 5-alkylidene-2-norbornenes, in which the alkylidene group contains from 1 to 20, preferably from 1 to 8 carbon atoms; the alkenyl norbornenes, in particular the 5-alkenyl-2-norbornenes, the alkenyl group of which contains from 2 to 20, preferably from 2 to 10 carbon atoms, for example vinylnorbornene, 5-(2'-methyl-2'butenyl)-2-norbornene and 5-(3'-methyl-2 'butenyl)-2-norbornene; dicyclopentadiene and the polyunsaturated compounds of bicyclo-(2,2,1)-heptane, bicyclo-(2,2,2)-octane, bicyclo-(3,2,1)-octane and bicyclo-(3,2,2)-nonane, at least one of the rings being unsaturated. Furthermore, compounds such as 4,7,8,9-tetrahydroindene and isopropylidenetetrahydroindene may be employed. Dicyclopentadiene, 5-methylene-2-norbornene or 5-ethylidene-2-norbornene or 1,4-hexadiene are used in particular. Mixtures of the aforementioned compounds may also be used. The diene may be present in the copolymer in amounts of up to 30% (wt), preferably up to 10-15% (wt). In addition to or in place of the diene, an unsaturated compound containing one or more functional groups such as halogen atoms, OH, OR, COOH, COOR or NH.sub.2 groups may be incorporated in the copolymer if desired, in an amount of up to 20% (wt). The molar ratio of the monomers applied is dependent on the desired polymer composition. Given the widely varying polymerisation rates of the monomers, it is not possible to give a universal range for the molar ratios. Normally, for the copolymerisation of ethylene and propylene a molar ratio of between 1:1 and 1:5 will be selected. If a polyunsaturated compound is to be copolymerised, the molar ratio thereof relative to ethylene will usually be from 0.0001:1 to 1:1. The polymerisation reaction is usually effected at a temperature of between -40 and 200.degree. C., preferably between 10 and 80.degree. C. The pressure will usually be 0.1-5 Mpa but higher or lower operating pressures are also possible. The process is preferably conducted continuously but may also be conducted semi-continuously or batchwise. The residence time may vary from a few seconds to a few hours. The residence time will normally be chosen to be between a few minutes and one hour. The polymerisation may take place in a liquid which is inert with respect to the catalyst, e.g. in one or more saturated aliphatic hydrocarbons such as butane, pentane, hexane, heptane, pentamethylheptane or petroleum fractions; in aromatic hydrocarbons, e.g. benzene or toluene, or in halogenated aliphatic or aromatic hydrocarbons, e.g. tetrachloroethylene. The operating temperature and pressure may be so chosen that one or more of the applied monomers, particularly the .alpha.-olefin, e.g. propylene, is liquid and is present in so large an amount that it acts as a dispersant. In that case, another dispersant is not needed. The process according to the invention may be conducted in a gas-filled or a liquid-filled polymerisation reactor or in a completely liquid-filled reactor. The use of a heterogenized catalyst allows the polymerisation process to be effected in suspension or in the gas phase. The molecular weight can be adjusted by techniques known to one skilled in the art. More particularly, this can be done by applying chain terminating agents such as diethyl zinc and preferably with hydrogen. Even very small amounts of hydrogen will suitably influence the molecular weight. After polymerisation, the polymer may be worked up in various ways. For liquid-phase processes, this may be done by evaporating the solvent or by steam coagulation. Amorphous copolymers obtained by the process according to the invention generally contain between 25 and 85% (wt) ethylene. However, products with an ethylene content of between 40 and 75% (wt) are preferred. Such copolymers are suitable for a plurality of applications, e.g. the manufacture of hoses, conveyor belts, sealing profiles. If desired, they may be vulcanized by the usual methods (for instance with the aid of free-radical donors, such as peroxides, or with sulphur). In order to allow the product to be processed as a rubber, the copolymer may be extended with oil; this is preferably done during the polymerisation process. It is known to add agents so as to prepare a friable bale. This may be effected by, for instance, adding talc or by employing a system as described in EP-A-427,339. The composition described therein, comprising an inorganic partioning agent, a thickener and binder reagent and an anionic dispersant, has been found to be well suited for use in the products according to the invention. In the preparation of EP(D)M the metallocenes of the present invention exhibit great differences from the traditional V-based Ziegler catalysts (such as VOCl.sub.3 and its derivatives). For example, the metallocene compound has a relatively high affinity to propylene and a much lower affinity to the third monomer. Also, propylene inversion takes place to a much lesser degree (approx. 20% in the case of the traditional catalyst and only approx. 0-5% if a metallocene according to the invention is used, measured with the aid of C13-NMR). Consequently, altogether different EP(D)M structures are obtained. The 2-indenyl compounds are applied in known manner, whether or not in combination with a cocatalyst, which is usually an organometal compound, in which the metal is chosen from group 1, 2, 12 or 13 of the Periodic System of Elements. Preference is given to an aluminium compound. For aluminium compounds-based cocatalysts, reference can be given to for instance EP-A-287,666, pages 20-21. Also suitable as cocatalysts are benzene-insoluble organo-aluminium-oxy compounds as disclosed in EP-A-360,492. See also U.S. Pat. No. 4,769,428 (5th column), where organoaluminium alkyls and linear and cyclic aluminoxanes are used as cocatalysts. The aluminoxanes may be prepared in the manner disclosed in these patent publications; they are also commercially available. Examples of commercially available aluminoxanes include methylaluminoxanes as manufactured by Schering, Ethyl and Akzo. The 2-indenyl compounds according to the invention may also be employed in the polymerisation of olefins without aluminoxanes being used as cocatalysts. The 2-indenyl compounds may, for instance, be converted to cationic compounds, which have catalytic activity. For the conversion into cationic compounds refer to, for instance, WO-A-91,09,882, EP-A-277,004 or WO-A-91,02,012. The 2-indenyl compounds according to the invention, in solid form or when suspended in an inert solvent, are highly stable and can therefore be stored for prolonged periods of time. The invention further relates to a polyolefin obtainable by polymerisation of (an) olefin(s) using a 2-indenyl compound according to the invention as a catalyst component. This particularly concerns EA(D)M polymers that stand out from state-of-the art products by a very small number of .alpha.-olefine inversions; the products according to the invention preferably have 0-5% .alpha.-olefine inversions in the chain. The invention will be illustrated by the following examples and comparative experiments. The indenyl compounds that were synthesized were analyzed through neutron activation analysis and H-NMR (hydrogen nuclear magnetic resonance). Neutron activation analysis was used to determine, for instance, the transition metal and halogen contents. H-NMR resulted in informations about the structure of the indenyl compounds. The H-NMR analyses were conducted using a Bruker AC200 NMR instrument at a frequency of 200 MHz. The samples for NMR analysis were prepared by adding c. 1 ml of deuterobenzene to 1-10 mg of the indenyl compound. The crystallization behaviour of the polymers obtained was determined by differential scanning calorimetry (DSC). After rapidly heating the sample to 200.degree. C. and holding it at that temperature for 5 minutes, the sample is cooled to -70.degree. C. at the rate of 10.degree. C./minute. The accompanying thermal effects are recorded. A "Hoekstra" value (a measure of the plasticity of the product) was measured on the rubbery polymers. This is done by placing a rubber sheet between two platens at a temperature of 106.degree. C. The platens are positioned at a distance of 1 mm. A load of 10 kg/cm.sup.2 is applied after 30 seconds so as to measure the distance between the platens after 15 seconds. The percentage decrease in thickness is the value of the Hoekstra plasticity. The intrinsic viscosity of the polymers obtained was determined by dissolving in decalin at 130.degree. C. |
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