GB2096123A - Magnesium halide production and use - Google Patents

Abstract

A solid magnesium or manganese halide material containing ions of a transition metal incorporated therein is prepared by adding to a fused magnesium or manganese halide a transition metal or a transition metal compound, and obtaining a solid magnesium or manganese halide material which contains ions of the transition metal. When using a transition metal compound, the valency of the transition metal in the solid magnesium or manganese halide material is different from its valency in the original transition metal compound. Using a transition metal, the fused salt may include a material which is capable of oxidising the transition metal to give ions of the transition metal, such materials being, for example, cadmium halide or zinc halide. The material which is capable of oxidising the transition metal may form volatile reaction by-products, or give solid by-products which are readily separated from the magnesium halide material. The solid magnesium or manganese halide material may be obtained in a suitable form by melt- spraying or grinding. Olefin polymerisation catalysts may include the product of this process.

Description

SPECIFICATION Magnesium halide production and use The present invention relates to a process for the preparation of a mixed halide material and to the use of the product as a component of a polymerisation catalyst system, particularly an olefin polymerisation catalyst system.

Olefin monomers such as ethylene, propylene and the higher alpha-olefins can be polymerised using the so-called Ziegler-Natta catalysts. The term "Ziegler-Natta catalyst" is generally used to mean a catalyst system obtained from a compound of a transition metal of Groups IVA, VA or VIA of the Periodic Table together with an organic compound of a non-transition metal. A typical system consists of a titanium chloride and an organo-aluminium compound. Such catalyst systems can be used to polymerise propylene and the higher alpha-olefins to produce a mixture of isotactic and atactic polymer, or to polymerise ethylene, optionally together with a comonomer. When polymerising propylene and the higher alpha-olefins, the commercially desired material is the isotactic polymer.However, in the production of a polymer such as polypropylene, some atactic polymer is inevitably produced and a considerable amount of work has been carried out in developing catalysts which give a low proportion of atactic polymer. For the production of ethylene polymers, and also polymers of propylene, effort has also been directed to the development of very active catalyst systems which are of such activity that there is no necessity to remove the catalyst residues from the polymer formed. However, it will be appreciated that in addition to having a high activity, the desired catalyst should be one capable of giving a polymer having desired properties. Thus, when polymerising or copolymerising ethylene, the catalyst should preferably give a good particle form, a desired molecular weight distribution and good incorporation of any comonomer.When polymerising propylene, the catalyst should be capable of producing an acceptable proportion of atactic polymer.

Catalysts of high activity are being studied and many attempts to produce catalysts of a sufficiently high activity have used supported systems. One series of supported catalysts uses a divalent metal halide as the support.

According to the present invention there is provided a process for the production of a solid magnesium and/or manganese halide composition which contains ions of at least one transition metal of Group VA, VA or VIA of the Periodic Table, which process comprises forming a melt of a metal halide of the formula MX2, incorporating into the melt at least one transition metal of Group VA, VA or VIA of the Periodic Table and/or at least one compound of a transition metal of Group VA, VA or VIA of the Periodic Table and obtaining a solid magnesium and/or manganese halide material containing ions of the at least one transition metal of Groups IVA, VA or VIA of the Periodic Table, wherein, M is magnesium and/or manganese; and X is a halogen atom; with the proviso that, when M is magnesium, 1) titanium trichloride is introduced into the melt only in the absence of titanium metal, 2) titanium metal is introduced into the melt only in the absence of titanium trichloride, and 3) when the only material incorporated into the melt is one compound of a transition metal of Group VA, VA or VIA of the Periodic Table, the valency of the transition metal of Group VA, VA or VIA of the Periodic Table which is contained in the one compound of a transition metal of Group VA, VA or VIA which is incorporated into the melt is different from the valency of at least some of the ions of the transition metal of Group IVA, VA or VIA of the Periodic Table which are contained in the solid magnesium halide material.

All references herein to the Periodic Table are to the Short Periodic Table as set out inside the back cover of "General and Inorganic Chemistry" by J R Partington, Second Edition, published by MacMillan and Company, London, in 1 954.

The term "transition metal" will be used hereafter to mean transition metals of Group VA, VA or VIA of the Periodic Table. The transition metal can be zirconium, vanadium, chromium or preferably, titanium. Alternatively, mixtures of transition metals, or mixtures of compounds of transition metals, or mixtures of both, may be used, particularly mixtures which include titanium or compounds of titanium.

For convenience hereafter, the metal halide of the formula MX2 will be referred to as the "divalent metal halide".

The transition metal and/or the compound of a transition metal may be incorpqrated into the melt of the divalent metal halide by adding the transition metal and/or the compound of a transition metal to the molten divalent metal halide. Alternatively, the transition metal and/or the compound of a transition metal may be added to solid divalent metal halide and the mixture heated until the divalent metal halide is molten to effect the desired incorporation.

In the accompanying drawings; Figure 1, formulae A to D represent materials which can be used in accordance with some aspects of the present invention; and Figure 2, graphs I and II show the absorption spectra of materials including solid magnesium halide materials obtained in accordance with the present invention.

If a transition metal is incorporated into the fused divalent metal halide, the transition metal is preferably in the form of powder or small pieces of foil in order to give a good rate of reaction.

However, we have found that the transition metal may be used in larger particulate form, for example as granules of 1 cm, or more, in diameter, but the use of such larger particles gives a slower rate of reaction.

When a transition metal is incorporated into the fused divalent metal halide, then the mixture must also incorporate a material which is capable of oxidising the transition metal to form the desired transition metal ions. This material will hereafter be referred to as "the oxidising agent".

The oxidising agent may be incorporated into the molten divalent metal halide using procedures similar to those described for the incorporation of the transition metal and/or transition metal compound. It is preferred that the oxidising agent is one which is capable of oxidising, and halogenating, the transition metal to form a transition metal halide. A material which is capable of oxidising and halogenating the transition metal will hereafter be referred to as the "halogenating agent". The halogenating agent may be an elemental halide, a hydrogen halide, a hydrocarbon halide such as carbon tetrachloride, or a halide of a metal which is readily reduced, or which is in a valency state which is readily reduced.If a metal halide is used as the halogenating agent, this metal halide may be such as to leave no residue in the melt at the end of the reaction, or to give a solid material which is readily separated from the melt. Hence, the halogenating agent can be a halide of a metal, which metal is sufficiently volatile to evaporate from the melt under the reaction conditions used, suitable metal halides of this type being cadmium chloride and zinc chloride. Alternatively, if the halogenating agent is an iron halide, for example ferrous or ferric chloride, this may form a precipitate of metallic iron which can be separated from the melt. Other metal halides which may be used as the halogenating agent include, inter alia, those of copper, gallium, bismuth, tin, lead, nickel, cobalt and manganese.It will be appreciated that if both a transition metal and a compound of a transition metal are incorporated into the melt of the divalent metal halide, the compound of a transition metal may act as an oxidising agent, or, if a halide of a transition metal is used, this may act as a halogenating agent. Thus, when both a transition metal and a compound of a transition metal are used, there may be no need to use an additional oxidising, or halogenating, agent.

The divalent rrietal halide is preferably' one in which X is a halogen atom other than fluorine and in paticular a compound in which X is chlorine.

The divalent metal halide used in the process of the present invention may contain water either as adsorbed water or, more typically, as a hydrated divalent metal halide. It is preferred to use an anhydrous magnesium halide, particularly anhydrous magnesium chloride. However, it is possible to use a hydrated divalent metal halide as the starting material and to pass a stream of a halogen-containing material, for example chlorine or hydrogen chloride, through the hydrated divalent metal halide whilst it is being heated, as a result of which the hydrated divalent metal halide is converted into the anhydrous divalent metal halide. If desired, a mixture of divalent metal halides may be used, for example a mixture of magnesium chloride and magnesium bromide or a mixture of magnesium and manganese chloride.

The divalent metal halide used may contain, or may have added to it, a minor proportion of anions other than halide ions. This minor proportion preferably does not exceed 10% of the total anions on an equivalent basis. The other anions may be hydroxide or oxide, for example as magnesium oxide, magnesium hydroxychloride or magnesium oxychloride.

The temperature at which the process is carried out is above the melting point of the divalent metal halide, or mixture containing the divalent metal halide. Magnesium chloride melts at a temperature of about 710"C but, in the presence of other materials, the melting point of the system may be higher or lower than 710"C. Thus, using magnesium chloride, the process is preferably carried out at temperature in'the range from 600"C up to 1 100"C, especially 720on up to 850"C. Manganous chloride melts at a temperature of about 650"C and thus can be used at similar temperatures to those used with magnesium chloride.As indicated previously herein, at such temperatures cadmium and zinc have an appreciable vapour pressure and thus can be readily removed from the melt, particularly if the procedure is carried out at a reduced pressure. Alternatively, in order to agitate the reaction mixture and to assist in the removal of volatile reaction products, a stream of an inert gas may be passed through the melt.

The quantity of the oxidising or halogenating agent used is preferably sufficient to oxidise all of the transition metal to form the desired transition metal ions. However with some oxidising, or halogenating agents, for example cadmium chloride, it is desirable to ensure that none of the metal from the oxidising or halogenating agent remains in the final product and with such systems we prefer to use an excess of the transition metal. In many processes according to the present invention which use an oxidising or halogenating agent and a transition metal, at least one mole of the oxidising or halogenating agent is required to oxidise one mole of the transition metal to form the desired transition metal ions. Thus, it is preferred that the molar proportion of the oxidising or halogenating agent is at least equal to the molar proportion of the transition metal. If the molar proportion of the oxidising or halogenating agent is in excess of the molar proportion of the transition metal, this excess may be necessary to oxidise all of the transition metal or, alternatively, may cause oxidation of the transition metal to a higher valency state or may be used to incorporate some of the oxidising or halogenating agent into the solid divalent metal halide material which is obtained as the product of the process of the present invention.

The oxidising or halogenating agent may be a gaseous material or a material which has a high vapour pressure under the reaction conditions and when using the oxidising or halogenating agent in this form, a gas stream which is, or which contains, the oxidising or halogenating agent is passed through the molten magnesium halide. When using the oxidising or halogenating agent in the gaseous or vapour form, the proportions thereof may be difficult to monitor and hence an excess of the oxidising or halogenating agent is typically used.

When the oxidising or halogenating agent is a metal halide, this may be mixed with the divalent metal halide prior to carrying out the process of the present invention. Alternatively, a composition containing the oxidising or halogenating agent and the divalent metal halide may be obtained using the procedure described in copending British Patent Application No.

8109405. More specifically, the metal halide which is the oxidising or halogenating agent is contacted at a temperatùre of at least 150"C with magnesium and/or manganese wherein the magnesium and/or manganese is more electropositive than the metal present in the oxidising or halogenating agent. The amount of the oxidising or halogenating metal halide should be in excess of that required to react with the magnesium and/or manganese in order to form a product containing the oxidising or halogenating metal halide. The procedure of Application No.

8109405 is preferably effected at a temperature which is above the melting point of the oxidising or halogenating metal halide, for example at a temperature of at least 500"C.

An an alternative to adding a transition metal and an oxidising or halogenating agent to the molten divalent metal halide, it is possible to use a compound of a transition metal with the proviso that when the divalent metal halide is a magnesium halide, the transition metal in the added compound has a different valency from the valency of the transition metal ions in the solid magnesium halide material which -is obtained as the product of the present invention.

Using a compound of a transition metal, the reaction conditions used, particularly temperature, are in general such that the compound of a transition metal may be used in the absence of any material other than the molten divalent metal halide. More specifically, titanium trichloride may be added to the divalent metal halide, such as magnesium chloride and, under the conditions in the molten divalent metal halide, the titanium trichloride will decompose to give titanium dichloride and volatile species such as chlorine.Alternatively, the transition metal compound may be a volatile compound such as titanium tetrachloride which can be introduced into the molten divalent metal halide as a vapour in a stream of an inert gas which is passed through the molten divalent metal halide with decomposition of the titanium tetrachloride to give titanium dichloride and chlorine occurring in the molten divalent metal halide. A mixture of a transition metal and a compound of a transition metal may be used, for example a mixture of titanium metal and titanium tetrachloride, and with such a mixture, the two materials may react together to produce the transition metal ions.

The quantity of the transition metal or compound of a transition metal which is added to the molten divalent metal halide can be varied within a wide range. However, it is preferred that the proportion of transition metal ions present in the final product is such that the proportion of transition metal atoms does not exceed the proportion of magnesium and/or manganese atoms present in the solid divalent metal halide material. More preferably, the proportion of the transition metal ions is such that between 0.1 and 40% of the metal atoms present in the final product are transition metal atoms.

Many of the transition metals which are used in the process of the present invention can exist in one of several valency states such as 2, 3, 4 and possibly 5 and 6. In general, the valency of the transition metal ions contained in the solid divalent metal halide material will be less than the maximum possible valency of the transition metal and typically will be the minimum valency, which is two for many of the transition metals which can be used in the present invention. However, the valency of the transition metal ions will be dependent upon the reaction conditions, particularly on the nature, and amount, of the oxidising or halogenating agent and also on the reaction temperature.If the oxidising or halogenating agent is used in an excess amount such that some of this agent remains in the solid divalent metal halide material, the valency of the transition metal ions may be greater than the minimum valency. Furthermore, the transition metal ions may exist in more than one valency state, for example as a mixture of the di and tri-valent states.

In addition to the transition metal ions, the solid divalent metal halide material may include ions of other metals such as zinc, iron, or aluminium. The ions of such other metals may be incorporated into the molten divalent metal halide in a manner similar to that used for the incorporation of the transition metal ions. However, if an excess of a metal halide is used as the halogenating agent, the use of such an excess may result in the incorporation of ions of the metal into the solid divalent metal halide material. The proportion of the ions of the other metals is preferably such that the proportion of atoms of the other metals does not exceed the proportion of magnesium and/or manganese atoms present in the solid divalent metal halide material.It is preferred that the proportions of the transition metal atoms and the atoms of the other metals are such that at least 50% of the metal atoms present in the final product are magnesium and/or manganese atoms. The proportion of the ions of the other metals is typically such that the other metaas constitute less than 20% of the total metal atoms present in the solid divalent metal halide material.

Depending on the materials used, including the particle size thereof, the reaction in the molten divalent metal halide may be very rapid or may take several hours. Thus, the reaction mixture in the molten divalent metal halide is maintained at a temperature such that the divalent metal halide is molten for a time of from one second up to 100 hours and typically at least one minute up to 20 hours. At the completion of the reaction, the divalent metal halide material obtained may be subjected to a zone refining technique in order to minimise the level of impurities in the bulk of the material.

At the completion of the reaction the molten material is cooled and solidified. Cooling may be achieved by rapid quenching, which results from plunging the reaction vessel-containing the molten material into a quenching bath containing a liquid such as water or liquid nitrogen.

Alternatively, the molten material may be allowed to cool in the furnace either by a controlled reduction in the temperature of the furnace by turning down the heating gradually or by a more rapid temperature reduction by switching off the heating at the end of the reaction. A further alternative is to remove the reaction vessel from the furnace and to allow the vessel and its contents to cool in air.

The solid divalent metal halide material can be used as a component of a polymerisation catalyst and thus it is preferred that this material is obtained as small particles, particularly particles having a maximum dimension of less than one millimetre, preferably between 5 and 400 microns, and especially from 10 up to 100 microns. On cooling the divalent metal halide material in the reaction vessel, a solid mass is obtained which may be broken down into the desired small particles. The solid mass may be broken down into small particles by a grinding technique, for example using a rotating or vibrating ballmill. If a grinding technique is used to effect break-dowii of the solid mass, it is preferred that the solid mass contains fine crystallites of the solid divalent metal halide material.A fine crystallite structure is conveniently obtained by cooling the melt at a rate of at least 5"C per minute through the liquid phase/solid phase transition. If the solid divalent metal halide material has been subjected to a zdne refining technique, the zone refined material will be a solid mass consisting of large crystals or possibly a single crystal and such a mass will be difficult to break down by a grinding operation. Thus, in order to obtain a material which is more readily broken down by grinding, the:zone refined material may be remelted and the resulating molten material then resolidified under conditions capable of giving a solid phase containing fine crystallites.

As an alternative method of obtaining the solid divalent metal halide material in a particulate form, the molten reaction product may be subjected to a melt-spraying procedure. This procedure avoids the need to use a grinding step and the particle size of the solid product may be controlled by suitable adjustment of the melt-spraying conditions.

As noted herein, the solid divalent metal halide material obtained by the process of the present invention can be used as a component of a polymerisation catalyst system and, in particular, as a component of an olefin polymerisation cataayst system. Since olefin polymerisation catalyst systems are susceptible to the effects of oxygen-containing materials, it is preferred to carry out all of the foregoing procedures in an atmosphere from which any oxygen-containing materials are substantially absent. Thus, the procedure is preferably carried out under vacuum or under an atmosphere of nitrogen or other inert gas such as argon or helium.

If desired, the solid divalent metal halide material may be treated with a transition metal compound which may be the same as, or different from, the transition metal material present in the solid divalent metal halide material. Alternatively, or in addition, the solid divalent metal halide material may be treated with a Lewis Base compound, preferably an organic Lewis Base compound. These treatments may be effected by grinding the solid divalent metal halide material with the transition metal compound and/or the Lewis Base compound, or by contacting the solid divalent metal halide material with a liquid medium which is, or which contains, the transition metal compound and/or the Lewis Base compound. If both a transition metal compound and a Lewis Base compound are used, these may be used as a complex thereof.

Suitable Lewis Base compounds are described in more detail hereafter. The transition metal compound is typically a halide, preferably a halide in which the transition metal is in its maximum valency, for example, titanium tetrahalide.

The amount of transition metal present in the solid divalent metal halide material can be determined using any suitable analytical technique such as, for example atomic absorption spectrometry using flame atomisation. Single-crystal spectra, measured at low temperatures (10auk) using wavelengths in the range 300 up to 1100 nm, can be used to determine the structure of the material. With solid magnesium halide materials containing titanium it has been found that the titanium is present in a distorted octahedral site in the lattice. This observation is confirmed by ESR spectra.

Using the process of the present invention we have obtained a solid homogenous magnesium chloride material containing divalent titanium ions in the lattice. In materials in which the Ti : Mg atomic ratio is less than 1:30, the spectrum in the wavelength range 300 to 1100 nm is typical of single centre Ti (li) ions in a distorted octahedral site in the lattice. Thus, the materials have absorption bands at wavelengths of about 635 nm and about 1050 nm. In materials having a higher titanium level (Ti:Mg atomic ratio of about 1 0), a new absorption band is observed in the range 350 to 365 nm. As the proportion of titanium is increased further, the band at 350 to 365 nm becomes more pronoounced.

Solid divalent metal halide materials such as those obtainable by the process of the present invention, may be used as one component of polymerisation catalyst system, particularly a catalyst system for the polymerisation of unsaturated monomers, for example ethylenically unsaturated hydrocarbon monomers.

Thus, according to a further aspect of the present invention there is provided a polymerisation catalyst system comprising 1) a composition containing at least one transition metal of Group IVA, VA, or VIA of the Periodic Table, which-composition is a product obtained by forming a melt of a divalent metal halide, incorporating into the melt at least one transition metal of Group VA, VA or VIA of the Periodic Table and/or at least one compound of a transition metal of Group IVA, VA OR VIA of the Periodic Table and separating from the mixture a solid divalent metal halide material containing ions of the at least one transition metal of Group VA, VA or VIA of the Periodic Table; and 2) an organic compound of aluminium or of a non-transition metal of Group IIA of the Periodic Table or a complex of an organic compound of a transition metal of Group IA or IIA of the Periodic Table with an organic compound of aluminium.

Component 1) of the catalyst may be a solid divalent metal halide material obtained in accordance with the present invention as hereinbefore described. However, other compositions containing at least one transition metal and obtained by incorporating a transition metal and/or compound of a transition metal into the molten divalent metal halide may be used, for example, the material obtained by incorporating titanium dichloride into molten magnesium chloride. It will be appreciated that such other materials may be obtained using a process w.hich is similar to the process of the present invention as hereinbefore described.

It will be appreciated that the composition which is component 1) of the catalyst system may also include, in addition to magnesium and/or manganese ions and ions of at least one transition metal of Group VA, VA or VIA of the Periodic Table, ions of other metals such as, for example, zinc, iron, or aluminium. Furthermore, the composition-containing the at least one transition metal may aaso include a Lewis Base compound which has been incorporated into the solid divalent metal halide material in a subsequent stage. There may also be present a proportion of at least one transition metal compound which has been incorporated into the solid divalent metal halide material in a subsequent stage. The composition which is component 1) may also include a minor proportion of anions other than halide ions, such as hydroxide or oxide.

Component 2) of the catalyst may be a magnesium-containing compound of the formula A or may be a complex of a magnesium compound with an aluminium compound, the said complex having the formula B in the attached formulae drawings, wherein each R', which may be the same or different, is a hydrocarbon radical; each Xl, which may be the same or different, is a group OR2 or a halogen atom other than fluorine; R2 is a hydrocarbon radical; a has a value of greater than 0 up to 2; b has a value of greater than 0 up to 2; and c has a value from 0 up to 3.

The groups R' are all typically alkyl groups and conveniently are alkyl groups containing from 1 up to 20 carbons atoms and especially from 1 up to 6 carbon atoms. The value of a is preferably at least 0.5 and it is particularly preferred that the value of a is 2. The value of b is typically in the range 0.05 up to 1.0. The value of c is typically at least 1 and is preferably 3.

If the component 2) is a complex of an organic compound of a metal of Group IA with an organic aluminium compound, this compound may be of the type lithium aluminium tetraalkyl.

However, it is preferred that the component 2) is an organic aluminium compound which may be, for example, an aluminium hydrocarbyl halide such as dihydrocarbyl aluminium halide, an aauminium hydrocarbyl sulphate or an aluminium hydrocarbyl hydrocarbyloxy but is preferably an aluminium trihydrocarbyl or a dihydrocarbyl aluminium hydride. The aluminium trihydrocarbyl is preferably an aluminium trialkyl in which the alkyl group contains from 1 up to 8 carbon atoms, for example an ethyl, butyl or octyl group.

Component 2) of the catalyst system is preferably an aluminium trihydrocarbyl compound and, if the catalyst system is to be used to polymerise propylene or a higher alpha-olefin monomer, it is preferred that the catalyst system also includes a separate component 3) which is a Lewis Base compound. The Lewis Base compound which is component 3), and also any Lewis Base compound which is present as part of component 1), is preferably an organic Lewis Base compound and can be any which has been proposed for use in a Ziegler polymerisation catalyst system and which effects either the activity or stereospecificity of such a system.Thus, the Lewis Base compound may be an ether, an ester, a ketone, an alcohol, an ortho-ester, a sulphide (a thioether), an ester of a thiocarboxylic acid (a thioester), a thioketone, a thiol, a sulphone, a sulphonamide, a fused ring compound containing a heterocyclic sulphur atom, an organo-silicon compound such as a silane or siloxane, an amide"such as formamide, urea and the substituted derivatives thereof such as tetramethylurea, thiourea, an alkanolamine, an amine, which term includes a cyclic amine such as pyridine or quinoline or a diamine or polyamine such as tetramethylethylenediamine, or an organo-phosphorus compound such as an organophosphine, an organo-phosphine oxide, an organo-phosphite or an organo-phosphate.The use of organo-Lewis Base compounds is disclosed, inter alia, in British Patent Specifications 803198, 809717, 880998, 896509, 920118, 921954, 933236,940125,966025, 969 074, 971 248, 1013363, 1017977, 1 049 723, 1122010, 1150845, 1208815, 1234657,1324173, 1 359 328, 1 383 207, 1423658,1423659 and 1423660.

Preferred Lewis Base compounds, which may be used as component 3), or which are present as part of component 1), are esters which may be represented by the formula C given in the attached formulae drawings.

In the formula C, R3 is a hydrocarbon radical which may be substituted with one or more halogen atoms and/or carbonoxy groups; and R4 is a hydrocarbon radical which may be substituted by one or more halogen atoms.

The groups R3 and R4 may be the same or different and it is preferred that one, but not both, of the groups R3 and R4 includes an aryl group. The group R3 is conveniently an optionally substituted alkyl or aryl group, for example a methyl, ethyl, or especially a phenyl, methyphenyl, methoxyphenyl or fluorophenyl group. The group R4 is preferably an alkyl group containing up to 6 carbon atoms, for example an ethyl or a butyl group. It is particularly preferred that R3 is an aryl or haloaryl group and R4 is an alkyl group. Esters of benzoic acid, anisic acid (4-methoxy benzoic acid) and P-toluic acid (4-methyl benzoic acid) are particularly preferred esters which may be present as component 3) of the catalyst system, or as part of component 1) of the catalyst system.

In addition to, or instead of, the Lewis Base compound which is component: 3), Ithe catalyst system may also include a substituted or unsubstituted polyene, which may be an acyclic polyene such as 3-methylheptatriene (1,4,6), or a cyclic polyene such as cyclooctatriene, cyclooctatetraene, or cycloheptatriene or the alkyl- or alkoxy-substituted derivatives of such cyclic polyenes, tropylium salts or complexes, tropolone or tropone.

The proportions of components 1) and 2) of the catalyst system can be varied within a wide range as is well known to the skilled worker. The particular preferred proportions will be dependent on the type of materials used and the absolute concentrations of the components but in general we prefer that for each gramme atom of transition metal which is present in component 1) of the catalyst system there is present at least one mole of component 2) and preferably at least 5 moles of component 2) of each gramme atom of transition metal. The number of moles of component 2) for each gramme atom of transition metal in component 1) may be as high as 1000 and conveniently does not exceed 500.

When a Lewis Base compound is present as component 3) of the catalyst system, it is preferred that the Lewis Base compound is present in an amount of not more than one mole for each mole of component 2) and particularly from 0.1 up to 0.5 mole of the Lewis Base compound for each mole of the component 2). However, depending on the particular organic metal compound and Lewis Base compound, the proportion of the Lewis Base compound which is present as component 3) may need to be varied to achieve the optimum catalyst system.

If the catalyst system includes a polyene, it is preferred that the polyene is present in an amount of not more than one mole for each mole of component 2), and especially from 0.01 up to 0.20 mole for each mole of component 2). If the catalyst system includes both a Lewis Base component and a polyene, it is preferred that both of these materials are together present in an amount of not more than one mole for each mole of component 2).

Catalysts in accordance with the present invention can be used to polymerise or copolymerise ethylenically unsaturated hydrocarbon monomers.

Thus, as a further aspect of the present invention there is provided a polymerisation process which comprises contacting, under polymerisation conditions, at least one ethylenically unsaturated hydrocarbon monomer with a catalyst in accordance with the present invention.

The monomer which may be contacted with the catalyst system is one having the formula D as set out in the accompanying formulae drawings.

In the formula D, R5 is a hydrogen atom or a hydrocarbon radical.

Thus, the monomer may be ethylene, propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, styrene, 1,3-butadiene or any other monomer which satisfies formula D. The monomer is preferably an olefin monomer, particularly an aliphatic monomer containing not more than 10 carbon atoms. The monomers may be homopolymerised or may be copolymerised together. If propylene is copolymerised it is preferred to effect the copolymerisation with ethylene, conveniently using a sequential copolymerisation process as is described in British Patents 970478; 970479 and 1 014944.If ethylene is being copolymerised using the process of the present invention, it is preferred to carry out the copolymerisation using a mixture of ethylene and the desired comonomer, for example butene-1 or hexene-1, wherein the mixture of monomers has essentially the same composition throughout the polymerisation process.

As is well known, Ziegler-Natta type catalysts are susceptible to the presence of impurities in the polymerisation systdm. Accordingly, it is desirable to effect the polymerisation using a monomer, and a diluent if this is being used, which has a high degree of purity, for example a monomer which contains less than 5 ppm by weight of water and less than 1 ppm by weight of oxygen. Materials having a high degree of purity can be obtained by processes such as those described in British Patent Specifications 1111493; 1226659 and 1 383 611.

Polymerisation can be carried out in the known manner, for example in the presence or absence of an inert diluent such as a suitably purified paraffinic hydrocarbon, in the liquid phase using an excess of the liquid monomer as the polymerisation medium or in gas phase, this latter term being used herein to mean the essential absence of a liquid medium.

If polymerisation is effected in gas phase, it may be effected by introducing the monomer, for example propylene, into the polymerisation vessel as a liquid and operating with conditions of temperature and pressure within the polymerisation vessel which is such that the liquid monomer vaporises, thereby giving an evaporative cooling effect, and essentially all of the polymerisation occurs with a gaseous monomer. Polymerisation in gas phase may be effected using conditions which are such that the monomer is at a temperature and partiaa pressure which are close to the dew point temperature and pressure for that monomer, for example as described in more detail in British Patent Specification 1 532 445.Polymerisation in gas phase can be effected using any technique suitable for effecting a gas-solid reaction such as a fluidised-bed reactor system, a stirred-bed reactor system or a ribbon blender type of reactor.

Using the catalyst systems of the present invention, ethylene may be polymerised or copolymerised, for example with butene-1 or hexene-1 as the comonomer, in a fluidised-bed reactor system to give a high yield of polymer. The fluidising gas is the gas mixture to be polymerised together with any hydrogen which is present as a chain transfer agent to control molecular weight. Thus, for the copolymerisation of ethylene and butene-1 to produce an ethylene copolymer having a density of less than about 940 kg/m3, the gas composition is typically from 50 to 60 mole % ethylene and 1 5 to 25 mole % butene-1 with the remainder, apart from inert materials and impurities, being hydrogen.

Polymerisation may be effected either in a batch manner or on a continuous basis, and the catalyst components may be introduced into the polymerisation vessel separately or some or all of the catalyst components may be mixed together before being introduced into the polymerisation reactor. It will be appreciated that pre-mixing of the catalyst components may be effected in the presence of a monomer and, if components 1) and 2) of the catalyst are pre-mixed in this manner, such pre-mixing will result in at least some polymerisation of the monomer before the catalyst system is introduced into the polymerisation vessel. If the polymerisation is being carried out in the gas phase, the catalyst components may be added to the polymerisation reactor suspended in a stream of the gaseous monomer or monomer mixture.

The polymerisation can be effected in the presence of a chain transfer agent such as hydrogen or a zinc dialkyl, in order to control the molecular weight of the product formed. If hydrogen is used as the chain transfer agent in the polymerisation of propylene, or higher alpha-olefin monomer, it is conveniently used in an amount of from 0.01 up to 5.0%, particularly from 0.05 up to 2.0% molar relative to the monomer.When the monomer being polymerised is ethylene, or a mixture in which ethylene is a major polymerisable component (by moles), the amount of hydrogen used may be greater than the amount used for propylene polymerisation, for example, in the homopolymerisation of ethylene the reaction mixture may contain in excess of 50% molar of hydrogen, whereas if ethylene is being copolymerised, a proportion of hydrogen which is typically up to 35% molar is used. The amount of chain transfer agent will be dependent on the at least one transition metal which is present in component 1) of the catalyst system.The amount of chain transfer agent will also be dependent on the polymerisation conditions, especially the temperature, which is typically in the range from 20 C up to 100"C, preferably from 50"C up to 85 C when the polymerisation pressure is relatively low, for example not exceeding 50 kg/cm2.

Polymerisation can be effected at any pressure which has been previously proposed for effecting the polymerisation of olefin monomers. However, although the polymerisation may be effected at pressures up to 3000 kg/cm2, at which pressures the polymerisation temperature may be as high as 300"C, it is preferred to carry out the polymerisation at relatively low pressures. Whilst the polymerisation may be effected at atmospheric pressure, it is preferred to use a slightly elevated pressure and thus it is preferred that the polymerisation is effected at a pressure of from 1 kg/cm2 up to 50 kg/cm2, preferably from 5 up to 30 kg/cm2.

It will be appreciated that the particle form of the polymer obtained iS dependent upon, and hence is affected by, the particle form of component 1) of the catalyst system. Hence, by appropriate treatment of the divalent metal halide material obtained as the product of the reaction in the molten divalent metal halide, the particle form of component 1) of the catalyst system may be adjusted and, in particular, an appropriate particle form may be achieved.

Various aspects of the present invention will now be described with reference to the following Examples which are illustrative of the invention. In the Examples, all operations are effected under an atmosphere of nitrogen unless otherwise indicated. All the glass apparatus was dried in an air overn at 120"C for at least one hour and purged with nitrogen before use.

EXAMPLE I 10 g of magnesium chloride (BDH technical grade) and 5.6 of cadmium chloride (BDH technical gradc referred to as "dried") were mixed in a silica ampoule. The ampoule had an internal diameter of 1 2 mm and was provided with a long neck of internal diameter 8 mm which terminated in a tap and a B 24 joint. The ampoule was evacuated to 10-2 to 10-3 Torr and was heated to about 800 C for ten minutes under vacuum, to melt the charge. The ampoule was allowed ato cool, the tap was closed and the ampoule was transferred to a dry box in which an atmosphere of dry nitrogen was being maintained.

The tap was opened and 1.8 9 of titanium was added in the form of pieces of foil of about 1 mm square. The tap was closed, the ampoule removed from the dry box and reconnected to the vacuum line. The tap was opened and the ampoule evacuated to 10-2 to 10-3 Torr. The neck of the ampoule was sealed, below the tap, using a gas torch.

The sealed ampoule was placed in a furnace and heated to a temperature in the range 800"C to 850"C and this temperature was maintained for 1 2 hours. The furnace was switched off and the ampoule allowed to cool over a period of two or three hours in the furnace to form small crystallites. A ring of cadmium metal was observed to have condensed around the top of the ampoule.

The ampoule was transferred back to the dry box and cracked open. The top and bottom of the contents of the ampoule were discarded to minimie impurity levels.

EXAMPLE 2 The procedure of Example 1 was repeated using 5 9 of magnesium chloride, 0.95 g of cadmium chloride and 0.35 g of titanium. By analysis, the product was found to contain 0.6% by weight of titanium.

EXAMPLE 3 The procedure of'Example 1 was repeated using 5 g of magneSium chloride, 2.8 g of cadmium chloride and 0.9 g of vanadium metal in powder form. By analysis, the product was found to contain 1.3% by weight of vanadium.

EXAMPLE 4 The procedure of Example 1 was repeated using 5 9 of magnesium chloride, 2.8 g of cadmium chloride, 0.45 g of titanium and 0.45 g of vanadium. By analysis the product was found to contain 2.2% by weight of titanium. The proporti6n of vanadium was not determined.

EXAMPLE 5 The procedure of Example 1 was repeated using 5 9 of magnesium chloride, 4.98 9 of cadmium chloride and 1.5 g of titanium. By analysis, the product was found to contain 9.9% by weight of titanium.

EXAMPLE 6 The procedure of Example 1 was repeated using 4.74 9 of magnesium chloride, 2.98 g of zinc chloride (BDH "Analar" grade) and 0.7 g of titanium. The product was found to contain 1.2% by weight of titanium. The product contained green and purple regions suggesting that the titanium was present in two different valency states.

EXAMPLE 7 The procedure of Example 6 was repeated using 5 g of magnesium chloride, 2.35 9 of zinc chloride (Alpha "ultrapure" grade, obtainable from Lancaster Synthesis, Lancaster, England) and 0.9 9 of titanium. The product was found to contain 7.7% by weight of titanium.

Spectra were obtained using materials containing the product of Example 1. Large crystals were obtained in the manner described hereafter. The crystals were cleaved perpendicular to the c axis and the cleaved samples were mounted and placed in a Displex (Air Products Limited) closed cycle refrigerator and cooled to 10"K. The spectra were obtained along the c axis using a Beckman Acta 4M spectrometer, the absorption curves being shown in Graphs I and II respectively of Fig. 2 in the accompanying drawings.

The sample used to produce the absorption curve of Graph I was obtained by mixing one gramme of the product of Example 1 with five grammes of magnesiums chloride which had been pre-grown as a single crystal (to purify the magnesium chloride) and thereafter crushed sufficiently to permit loading of the crushed magnesium chloride into the ampoule described hereafter. The materials were placed in an ampoule of 8 mm internal diameter by placing a small quantity of magnesium chloride at the bottom, then the product of Example 1 and then five grammes of the crushed magnesium chloride. The ampoule was then evacuated by connecting it to a vacuum line at 10-3 torr for one hour. The exit tube at the top of the ampoule was then sealed by fusion.The sealed ampoule was lowered through a vertical furnace at a rate of one miliimetre per hour as described by W.E. Smith, J.C.S. Dalton, 1969, page 2677. The temperature at the top of the furnace was 800"C and at the bottom 700"C, with a temperature gradient in the middle region of the furnace. The contents of the ampoule were then removed and a sample from the middle of the ampoule contents was used to obtain a spectrum in the manner hereinbefore described. The spectrum obtained is shown as Graph I.

A further sample was prepared in a similar manner but using a mixture of threw X grammes of the product of Example 1 and three grammes of pre-ground magnesium chloride to catkin the spectrum shown as Graph II.

In Graph I, a small absorption band can be seen at a wavelength of 350 to 365 nm. This band is more noticeable in Graph II.

EXAMPLE 8 Into a stainless steel mill of length 15.2 cmand diameter 7.9 cm, and fitted internally with four metal strips, were introduced 200 stainless steel balls of 12.7 mm diameter and 200 stainless steel balls of 63.5 mm diameter. The mill was sealed, evacuated to 0.2, mm of mercury, and purged with nitrogen to give a nitrogen atmosphere in the mill The product of Example 1 was roughly crushed under nitrogen and this roughly crushed material was introduced into the mill. The mill was rotated at 1 20 rpm for 1 8 hours without cooling. The temperature of the exterior of the mill rose slightly, and, after milling, the temperature inside the mill was approximately 30"C.

At the end of the milling, about 100 cm3 of an aliphatic hydrocarbon fraction consisting essentially of pentamethylheptane isomers and have a boiling point in the range 1 70 to 185"C (hereafter "the aliphatic hydrocarbon") were added to the mill under nitrogen. The product was removed from the mill by shaking. The procedure was repeated until most of the milled solid had been recovered from the mill and the volume of the suspension obtained was about 250 cm3. A sample of the suspension was subjected to elemental analysis from which the formula TiMg3,11Cl796 was deduced. A further sample of the suspension was acidified with degassed 2M sulphuric acid and titrated with ceric sulphate solution from which the concentration of titanium in the suspension was found to be 0.1 molar.

An aliquot of the suspension was used to polymerise propylene.

The propylene used for the polymerisation had been purified by passing gaseous propylene in turn through a column (7.6 cm in diameter, 0.9 m in length) containing 1.6 mm granules of Alcoa F1 alumina at 50-60"C, and then through a similar column containing BTS catalyst (cupric oxide' reduced to finely divided metallic copper on a magnesium oxide support) at 40-50"C, condensing the issue gas and passing the liquid propylene through four columns (all 7.6 cm in diameter; two of 0.9 m in length, two of 1.8 m in length) at 25"C, each containing 1.6 mm pellets of Union Carbide 3A molecular sieves.

This treatment reduced the water content of the monomer from 5-10 ppm by volume to < 1 ppm by volume and the oxygen content from 1-2 ppm by volume to < 0.5 ppm by volume.

The level of inert compounds (nitrogen, ethane, etc.) was unchanged at 0.3% and the level of unsaturated hydrocarbons (allene, methyl-acetylene etc.) was unchanged at < 1 ppm.

A polymerisation flask equipped with efficient stirrer and a water jacket was dried carefully and one litre of the aliphatic hydrocarbon was introduced into the flask. The aliphatic hydrocarbon was evacuated at 60"C, purged with nitrogen and evacuated, which treatment effectively reduced the water and oxygen contents of the aliphatic hydrocarbon to below 10 ppm by weight.

The aliphatic hydrocarbon was then saturated with the purified propylene, which contained 0. 12% molar of hydrogen, to one atmosphere pressure. 10 millimole of triethyl aluminium was introduced into the polymerisation flask. After half an hour, some of the suspension obtained as described herein, was introduced into the polymerisation flask in an amount sufficient to provide two millimoles of titanium. The pressure in the polymerisation flask was maintained at one atmosphere by supply of propylene containing 0.12% molar of hydrogen. After a period of 3 hours from the introduction of the titanium-containing suspension, the run was terminated with 5 ml of isopropanol and 5 ml of propylene oxide, and a sample of supernatant liquid extracted for determining the concentration of soluble polymer dissolved in the polymerisation diluent.The solid was filtered and washed three times with petrol ether and dried in a vacuum oven at 120"C for an hour.

The yield of solid (insoluble) polymer was 1 5.4 9 and the yield of soluble polymer was 17.29.

EXAMPLE 9 The polymerisation process of Example 8 was repeated with the exception that purified ethylene containing < 1 ppm of water and oxygen was used instead of the propylene-hydrogen mixture, and that one millimole of titanium was used. After one hour, the polymerisation was terminated by the addition of isopropanol and the polymer was separated, washed with a hexane fraction and dried in a vacuum over at 80 for one hour. The yield of polymer obtained was 85.9 9.

By analysis, the polymer was found to contain 500 ppm of titanium, which corresponds to a conversion 95.8 9 polymer per mMol of titanium.

EXAMPLES 10 TO 14 The solids obtained in Examples 2, 3, 4, 5 and 7 were ball-milled in a manner similar to that described in Example 8 with the exception that a different quantity of solid was used.

Ethylene was polymerised as described in Example 9 using the solid in amounts to provide various quantities of transition metal. Further details of the polymerisation conditions, and the results obtained, are set out in the following Table One.

TABLE ONE Catalyst Amount Polyn Polymer Type (mM) Time Yield Activity Example (a) (b) (Hours) (g) (9. polymer/mM Ti/hr) 10 2 0.068 3 18.8 92 11 3 0.124 3 8.9 24 12 4 0.5 3 15.9 10.6 13 5 3.4 1 28.7 8.4 14 7 0.03 4 89.6 747 Notes to Table One a) The product of Examples 2, 3, 4, 5 and 7 respectively.

b) Millimoles of total transition metal.

EXAMPLE 15 A) Preparation of magnesium bromide-zinc bromide material A large silica ampoule was dried in an oven at a temperature of 120"C and transferred to a glove box with a dry nitrogen atmosphere. 35 9 of anhydrous zinc bromide (BDH, lab reagent grade) were added to the ampoule which was then closed with a tap and connected to a vacuum line. The ampoule was evacuated to a pressure of 10-2 torr and the contents were melted gently using a gas torch. The ampoule was cooled, the tap closed and the ampoule returned to the glove box. 2.7 9 of magnesium (BDH Grignard grade) were added. The tube was again closed and connected to the vacuum line. The ampoule was evacuated and sealed by fusion of the silica of the neck, below the tap.

The sealed ampoule was transferred to a vertical furnace and the temperature raised to between 500"C and 550"C. The temperature was maintained for 1 6 hours before the furnace was switched off and allowed to cool for 2 hours. The ampoule was transferred to the glove box and cracked open. Zinc metal pellets which were formed as a by-product in the reaction were removed from the reaction product.

B) Preparation of magnesium bromide doped with titanium The reaction product of stage A) was placed in another dried ampoule and 2.2 9 of titanium were added. The ampoule was closed, connected to the vacuum line, evacuated and sealed by fusion of the silica. The sealed ampoule was placed in the furnace used in stage A) and the temperature was raised to between 800"C and 850 'C. This temperature was maintained for 1 6 hours and then the sample was allowed to cool for 2 hours.

The ampoule was transferred to the glove box, cracked open and the contents removed. The top and bottom of the polycrystalline mass were discarded and the remainder was roughly crushed using a mortar and pestle and then transferred to a nitrogen filled vessel.

EXAMPLE 16 The procedure of Example 1 5 was repeated with the exception that, in stage A), 28.1 9 of zinc chloride were used in place of the zinc bromide and 8.25 9 of manganese metal (BDH electrolysis grade) were used instead of magnesium metal, whilst in stage B) 2.9 9 of titanium metal were used.

The procedure of stage A) of Examples 1 5 and 1 6 is jn accordance with the procedure of copending British Patent application No. 8109405.

EXAMPLES 17 AND 18 The products of Examples 1 5 and 1 6 were ball-milled in a manner similar to that described in Example 8 with the exception that a different quantity of solid was used. At the end of the milling, about 100 cm3 of the aliphatic hydrocarbon were added to the mill under nitrogen and a further milling was effected for a period of one hour. The product was then removed from the mill by shaking. A further 100 cm3 of the aliphatic-hydrocarbon were then added to the mill and the mill was shaken to remove most of the remaining milled solid from the mill.

The suspensions obtained were used to polymerise ethylene as described in Example 9 with the following modifications. Polymerisation was effected in 500 cm3 of an isoparaffin fraction essentially all of which had a boiling point in the range 117 C to 135"C (hereafter referred to as the "isoparaffin fraction"). The isoparaffin fraction contained 8 millimoles of triisobutyl aluminium, 8 cm3 of hexene-1 and 50 ppm of an antistatic agent of the formula C6F13O(CH2CH20)8CnH(2n 1)' where n has a value of from 1 6 to 1 8.

The amount of the titanium component used, and the activity achieved, are set out in Table Two.

TABLE TWO Catalyst Amount Activity Type (mM) (9. polyer/mM Ti/hr) Example (c) (b) (d) 17 1.5 0.156 (67* (43" 18 16 0.144 125"" Notes to Table Two (b) is as defined in notes to Table One.

(c) The product of Examples 1 5 and 1 6 respectively.

(dafter 1 2 minutes polymerisation **after one hours polymerisation.

Claims (20)

1. A process for the production of a solid magnesium and/or manganese halide composition which contains ions of at least one transition metal of Group VA, VA or VIA of the Periodic Table, which process comprises forming a melt of a metal halide of the formula MX2, incorporating into the melt at least one transition metal of Group VA, VA or VIA of the Periodic Table and/or at least one compound of a transition metal of Group IVA, VA or VIA of the Periodic Table and obtaining a solid magnesium and/or manganese halide material containing ions of the at least one transition metal of Groups IVA, VA or VIA of the Periodic Table, wherein, M is magnesium and/or manganese; and X is a halogen atom; with the proviso that, when M is magnesium, 1) titanium trichloride is introduced into the melt only in the absence of titanium metal, 2) titanium metal is introduced into the melt only in the absence of titanium trichloride, and 3) when the only material incorporated into the melt is one compound of a transition metal of Group IVA, VA or VIA of the Periodic Table, the valency of the transition metal of Group IVA, VA or VIA of the Periodic Table which is contained in the one compound of a transition metal of Group IVA, VA or VIA which is incorporated into the melt is different from the valency of at least some of the ions of the transition metal of Group IVA, VA or VIA of the Periodic Table which are contained in the solid magnesium halide material.

2. A process as claimed in claim 1 wherein a mixture of transition metals, a mixture of compounds of transition metals or a mixture of both one or more transition metals and one or more compounds of a transition metal are incorporated into the melt.

3. A process as claimed in either claim 1 or claim 2 wherein at least one transition metal is incorporated into the melt and a material which is capable of oxidising the at least one transition metal to form transition metal ions is also incorporated into the melt.

4. A process as claimed in claim 3 wherein a material which is capable of oxidising and halogenating the transition metal is incorporated into the melt

5. A process as claimed in claim 4 wherein the material which is capable of oxidising and halogenating the transition metal is a halide of a metal which is readily reduced or which is in a valency state which is readily reduced.

6. A process as claimed in claim 5 wherein the halide of a metal is cadmium chloride, zinc chloride, ferrous chloride, ferric chloride or a halide of a transition metal.

7. A process as claimed in any one of claims 3 to 6 wherein the oxidising agent is used in an amount sufficient to oxidise all of the at least one transition metal to form transition metal ions.

8. A process as claimed in claim 6 wherein the halide of a metal is cadmium chloride and an excess of the at least one transition metal is incorporated into the melt.

9. A process as claimed in any one of claims 1 to 8 wherein either in the metal halide of the formula MX2, some of the halide ions are replaced by anions other than halide ions, or the metal halide of the formula MX2 has added to it anions other than halide ions, wherein the proportion, on an equivalent basis, of the other anions is not more than 10% of the total anions.

10. A process as claimed in any one of claims 1 to 9 wherein the metal halide of the formula MX2 is magnesium chloride and the temperature is in the range from 720"C up to 850"C.

11. A process as claimed in any one of claims wherein a mixture of titanium metal and titanium tetrachloride are incorporated into the melt.

1 2. A process as claimed in any one of claims 1, 9 or 10 wherein titanium tetrachloride is passed into molten magnesium halide.

1 3. A process as claimed in any one of claims 1 to 1 2 wherein the solid magnesium and/or manganese halide material is obtained as a solid mass and is broken down into small particles by grinding.

14. A process as claimed in any one of claims 1 to 1 3 wherein the solid magnesium and/or manganese halide material is treated with a transition metal compound and/or a Lewis Base compound.

1 5. A solid homogeneous magnesium chloride material containing diva lent titanium ions in the lattice and having absorption bands at wavelenghts of about 1050 nm, 635 nm and in the range 350 to 365 nm.

1 6. A polymerisation catalyst system comprising 1 a) a composition as claimed in claim 1 5 or, 1 b) a composition containing at least one transition metal of Group IVA, VA, or VIA of the Periodic Table, which composition is a product obtained by forming a melt of a metal halide of the formula MX2; incorporating into the melt at least one transition metal of Group IVA, VA or VIA of the Periodic Table and/or at least one compound of a transition metal of Group IVA, VA or VIA of the Periodic Table and separating from the mixture a solid magnesium and/or manganese halide material contairiing ions of the at least one transition metal of Group VA, VA or VIA of the Periodic Table; and 2) an organic compound of aluminium or of a non-transition metal of Group IIA of the Periodic Table or a complex of an organic compound of a transition metal of Group IA or IIA of the Periodic Table with an organic compound of aluminium, wherein M is magnesium and/or manganese; and X is a halogen atom.

1 7. A catalyst as claimed in claim 1 6 which contains as component lea), a solid magnesium halide material obtained by a process as claimed in any one of claims 1 to 14.

18. A catalyst as claimed in either claim 1 6 or claim 17, which also includes a Lewis Base compound and/or a polyene.

1 9. A polymerisation process comprising contacting, under polymerisation conditions, at least one ethylenically unsaturated hydrocarbon monomer with a catalyst as claimed in any one of claims 16 to 18.

20. A polymerisation process as claimed in claim 19 wherein the ethylenically unsaturated hydrocarbon monomer is a monomer of the formula CH2 = CHR5 wherein R5 is a hydrogen atom or a hydrocarbon radical.