GB2096122A - Metal halide production and use - Google Patents

Abstract

A halide of a metal is contacted at a temperature of at least 150 DEG C with at least one metal which is more electro-positive than the metal which is present in the metal halide. The contacting may be effected in the presence of an inert material such as an inorganic oxide or carbon. The metal halide may be zinc chloride or cadmium chloride. The more electro-positive metal may be a transition metal such as titanium or vanadium or a non-transition metal such as magnesium or aluminium, or a mixture. The optional inert material may be silica, alumina, or graphite. The reaction temperature may be so high that the metal in the metal halide can be vaporised under the reaction conditions. The product obtained may be used directly as a component of an olefine polymerisation catalyst or may be reacted with a transition metal compound to give a component of an olefine polymerisation catalyst. Olefine polymerisation catalysts incorporating the reaction product and the use of such catalyst systems is also disclosed.

Description

SPECIFICATION Metal halide production and use The present invention relates to a process for the production of a metal halide and to the use of such metal halides as a component of, or in the production of a component of, a polymerisation catalyst system particularly an olefin polymerisation catalyst system.

The so-called Ziegler-Natta catalysts can be used to polymerise olefine monomers such as ethylene, propylene and the higher a-olefines. The term "Ziegler-Natta catalyst" is generally use to mean a catalyst system obtained from a compound of a transition metal of Groups IVA, or or VIA of the Periodic Table together with an organic compound of a non-transition metal. A typical system consists of a titanium halide and an organo-aluminium compound. Such catalyst systems can be used to polymerise the olefine monomers to give high molecular weight olefine polymers. Considerable work is being carried out to develop catalyst systems having a polymerisation activity which is such that removal of catalyst residues from the polymer is not necessary.In many instances, such high activity catalyst systems are based on transition metal compounds on a suitable support material. Supported catalyst materials can be obtained by a procedure which includes a ball-milling stage and the product obtained has a wide particle size distribution which in turn affects the particle form of the polymer obtained. There is now interest in obtaining polymers which have good particle form and particle size distribution and this in turn means that the initial catalyst system must also have good particle form and particle size distribution.

Accoding to the present invention there is provided a process for the production of a metal halide material which process comprises contacting, at a temperature of at least 1 50 C, a halide of a metal (M') with at least one metal (M2) which is more electro-positive than M1.

The formulae A to D in the accompanying formulae drawings represent compounds which may be used in accordance with the present invention.

The metal M' is typically a metal of Group IIB of the Periodic system and in particular is zinc or cadmium. The halide is preferably a chloride.

The metal M2 may be a transition metal of Group IVA, VA or VIA of the Periodic Table and hereinafter, for convenience, the term "transition metal" will be used to mean "transition metal of Group VA, VA or VIA of the Periodic Table". Alternatively, the metal M2 is other than a transition metal (as hereinbefore defined) and such alternative metals M2 may be non-transition metals, for example magnesium or aluminium, or transition metals of Groups VI IA, VIII and IB of the Periodic Table, for example manganese. More than one metal M2 may be used including mixtures of transition metals, mixtures of metals other than the transition metals, or mixtures of both transition and non-transition metals, for example titanium and vanadium, magnesium and aluminium or titanium and magnesium.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 Limited, London, in 1954.

The reaction between the halide of M1 and the metal M2 may be effected in the presence of an essentially inert material (hereinafter referred to simply as "inert material") such as an inorganic oxide or carbon.

Thus, as a preferred aspect of the present invention, there is provided a process which comprises forming a mixture, or reaction product, of a halide of M1 with an inert material and simultaneously or subsequently contacting the mixture or reaction product with a metal M2, the contacting with the metal M2 being effected at a temperature of at least 1 50 C.

If the inert material is an inorganic oxide, this is a solid material and is preferably an oxide of a metal (which term is used herein to include silicon), particularly a metal of Groups I to to IV of the Periodic Table. The inorganic oxide is preferably a material which is substantially inert to the halide of M' under the reaction conditions used. However, the inorganic oxide may have some reactive sites which are typically present in a hydroxylic surface which is free from adsorbed water. By "hydroxylic surface" is meant a surface having a plurality of -OH groups attached to the surface, the hydrogen atom of the -OH group being capable of acting as a proton source, that is, having an acidic function. An inorganic oxide having a hydroxylic surface is substantially inert in that the bulk of the inorganic oxide is chemically inert.Inorganic oxides which may be used in the process of the present invention include silica, alumina, magnesia and mixtures of two or more thereof for example magnesium trisilicate which may be represented as (MgO)2(- SiO2)3xH20 (x is a positive number). Particularly useful inorganic oxides are silica and alumina.

Alternatively, if the inert material is carbon, this may be any form of carbon such as, for example, carbon black, or graphite.

The temperature at which the metal M2 is contacted with the halide of M' will be dependent on the nature of both the reactants and the reaction products obtained. The temperature is typically at least 300"C and is preferably above melting point of the halide of M1. The temperature is also preferably above the melting point of the metal M1. It is particularly preferred that the temperature and pressure at which the contacting with the metal M2 is carried out are such as to give vaporisation of the metal M1.Typically, if the metal halide is a zinc or cadmium halide, contacting with the metal M2 can be effected at a temperature of at least 500"C, for example in the range 700 up to 900"C. It will be appreciated that the halide of M' may be mixed with the at least one metal M2, and the optional inert material at a low temperature which is conveniently ambient temperature (about 1 5'C up to 30'C) and the mixture then heated to the desired elevated temperature. The elevated temperature of at least 1 50"C is maintained for a sufficient length of time to permit reaction between the metal M2 and the halide of the metal M'.The reaction occurs with the formation of a halide of the at least one metal M2 whilst the halide of M1 is reduced either to a halide in which M' has a lower valency or to the metal M'. The period of contacting the halide of M' with the at least one metal M2 at the temperature of at least 1 50"C may be from one second up to 100 hours and is typically at least one minute up to 20 hours. Under the temperature conditions used, particularly when the temperature is at least 500"C, zinc and cadmium both have an appreciable vapour pressure and thus can be removed from the reaction mixture, particularly if the procedure is carried out at a reduced pressure.Alternatively, in order to agitate the reaction mixture, and also to assist in the removal of volatile reaction products, a stream of an inert gas such as nitrogen or argon gas may be passed through the reaction mixture.

The at least one metal M2 is preferably added to the halide of M1 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 metal M2 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.

For convenience hereafter, the product obtained by contacting the halide of M' with the metal M2 will be referred to simply as the "reaction product". The reaction product is, or includes, a halide of the at least one metal M2. Some metals M2 form halides which are volatile at relatively low temperatures, for example aluminium chloride sublimes at 183'C under atmospheric pressure. Hence, if the metal M2 is, or includes, a metal, such as aluminium, which forms a volatile halide, it will be necessary to make allowance for this in effecting the process of the present invention. Thus, for example, if M2 is aluminium, it may be desirable to effect the reaction in a pressure resistant apparatus under a pressure which is greater than the vapour pressure of aluminium chloride at the reaction temperature.Alternatively, the reaction mixture may include a material which is effective to reduce the vapour pressure of the volatile halide, for example by the formation of a mixed melt with the volatile halide. When M2 is aluminium, a suitable material for this purpose is sodium chloride since mixtures of sodium chloride and aluminium chloride, for example those in which the atomic ratio of sodium to aluminium is in the range from about 1:3 to about 1:1, form homogeneous molten phases of low volatility at temperatures of up to about 500"C.

Thus, as a further aspect of the present invention there is provided a process which comprises contacting, at a temperature of at least 1 50 C, a halide of M' with at least one metal M2, where M2 forms a volatile halide, the process being effected in the presence of a halide of a metal (M3), wherein the halide of M3 is inert under the reaction conditions but is capable of forming a homogeneous molten phase with the volatile halide of the metal M2.

The reaction product obtained by the process of the present invention is a halide of the at least one metal M2 and may also include the halide of the metal M1 if this is used in an excess amount. The reaction product may also include other materials such as the optional inert material, or additionally or alternatively a halide of the metal M3 which is present during the reaction as an inert medium and which may act as a solvent, or complexant, for the halide of the metal M2.

The proportions of the halide of M' and the metal M2 which are used are preferably such that complete reaction of the metal M2 occurs, which will depend on the valency of M1 in the halide of M' and the valency of M2 in the reaction product. In general, it is necessary to use at least one mole of the halide of M' for each mole of the metal M2. Preferably, for each mole of the metal M2, there are used from one up to five moles of the halide of M'. However, with some of the halides of M', for example cadmium chloride, it is desirable to ensure that none of the metal M1 remains in the final product and with such halides of M', we prefer to use an excess of the metal M2. However, the presence of materials such as cadmium chloride in the reaction produce may be desirable if the reaction product is used in a further reaction in which the excess cadmium chloride reacts whereby the product of the further reaction does not contain any cadmium or cadmium chloride.

Thus, by the process of the present invention there may be obtained a product which is a magnesium halide, a titanium halide or a vanadium halide, or a mixture of two of more thereof, or a mixture or one or more thereof with a halide of M' and/or a halide of a metal M3 which is inert under the reaction conditions. The reaction product may also include an inert material which is an inorganic oxide such as silica or alumina or which is carbon and which inert material may act as a support for the metal halide or metal halide mixture. The reaction product may include a transition metal halide and, as described in more detail hereafter, such a reaction product may be used as a component of a polymerisation catalyst system.Alternatively, the reaction product may be further reacted with a compound of a transition metal whereby at least some of the transition metal compound is adsorbed on the surface of the reaction product, and the transition metal containing product thus obtained may then be used as a component of a polymerisation catalyst. Alternatively, a product containing a transition metal may be obtained by the process of copending British Patent Application No. 8109404, as described in more detail hereafter.

If an inert material is present when the halide of M1 is reacted with the at least one metal M2, all r+ the materials may be mixed together and reacted in a single step, or the inert material may be mixed, or reacted, with one of the reagents which is the halide of M' or the metal M2, and the material thus obtained is then contacted with the other reagent. If pre-mixing or pre-reaction is effected, it is preferred that the inert material is mixed or reacted with the halide of M' and the material thus obtained is then contacted with the at least one metal M2.

The pre-mixing or reaction of the halide of the metal M1 and the optional inert material may be effected under conditions similar to those used for the contacting with the metal M2. Thus, the solid halide of M1 may be mixed with the inert material and the mixture then heated to an elevated temperature which is preferably in excess of the melting of M1. In general, the temperature to which the mixture is heated is not substantially in excess of the melting point of the halide of M1 and when using zinc or cadmium chloride is conveniently in the range 300"C up to 500"C. The elevated temperature is maintained for a sufficient time to allow adsorption of the halide of M' onto the inert material, for example a time of from 30 seconds up to 10 hours, particularly from one minute up to an hour.The metal M2 may then be added to the material thus obtained and the continuing procedure is then as hereinbefore described.

Alternatively, since the halides of M' are generally soluble in water, an aqueous solution of the halide of M1 may be contacted with the inert material and the mixture stirred for a time sufficient to allow adsorption of at least some of the halide of M' from the solution onto the surface of the inert material. The inert material with the adsorbed halide of M1 is then separated from the aqueous medium and dried, preferably at a temperature of at least 1 00 C and especially at least 300"C, for a time sufficient to remove most, if not all, of the water.The time required for drying the solid is dependent on the temperature of drying and is typically from 0. 1 up to 20 hours, for example, from 1 up to 5 hours at 300"C. Adequate drying may be assisted by the use of- reduced pressure or by passing a stream of a dry inert gas through the solid. The product thus obtained may then be contacted with the metal M2 in the manner hereinbefore described.

If the aqueous solution of the halide of M1 which is contacted with the inert material is a zinc chloride solution, hydrated zinc chloride is adsorbed on the inert material and, on heating, this forms an hydros zinc chloride. This behaviour is different from the behaviour of many hydrated metal halides, which, on heating, tend to form oxy-halides, hydroxy-halides or other oxygencontaining materials.

The reaction product may be subjected to subsequent treatments, which are typically effected to incorporate ions of a transition metal into the reaction product. In one such subsequent treatment, the reaction product is contacted with a transition metal compound. The contacting with the transition metal compound may be effected by any suitable technique. Thus, the reaction product, which may contain a transition metal halide, may be contacted with a solution of a transition metal compound in an inert solvent, for example a hydrocarbon solvent such as heptane or hexane. Alternatively, if the transition metal compound is a liquid, the reaction product may be contacted with the liquid transition metal compound.The transition metal compound used for this subsequent treatment is preferably a halogen-containing material, particularly a chlorine-containing material, for example, titanium tetrachloride, vanadium tetrachloride, vanadyl trichloride (VOCI3) or the complex material titanium dichloride-aluminium chloride-arene. The contacting with the transition metal compound may be effected at ambient temperature but with some transition metal compounds, for example titanium tetrachloride, it is preferred that the contacting is effected at an elevated temperature, particularly in excess of 80"C up to the boiling temperature of the liquid medium.

The subsequent treatment with the transition metal compound may, alternatively, be effected by milling the reaction product in the presence of a transition metal compound. Alternatively, a gas stream containing vapours of the transition metal compound may be passed through the reaction product.

In a yet further alternative subsequent treatment, the reaction product may be subjected to a process in accordance with copending British Patent Application 8109404. In accordance with Application 8109404, 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 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 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 maganese; 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.The metal halide MX2 is a magnesium and/or manganese halide and it will be appreciated that, in accordance with the present invention, the metal M2 may be magnesium or manganese.

Furthermore, in accordance with Application 8109404, the melt can also include a material which is capable of oxidising the at least one transition metal to form transition metal ions. This additional material may be zinc chloride or cadmium chloride, either of which may be used, in excess, as the halide of M' in accordance with the present invention.

If the reaction product is, or includes, a transition metal halide, the subsequent treatment may be effected using a transition metal compound which is the same as, or different from, the transition metal halide which is present in the reaction product.

The quantity of the transition metal compound used in any subsequent treatment will be dependent on the reaction conditions used, the transition metal compound being used and the quantity, and type, of any transition metal which is present in the reaction product. The quantity of the transition metal compound is preferably sufficient to ensure the presence of at least 0.01 millimole of transition metal for each gramme of the reaction product, and preferably the final product contains from 0.1 up to 2.0 millimole of transition metal per gramme. In the subsequent treatment, an excess quantity of the transition metal compound can be used and the excess may be removed subsequently. The period of reaction is preferably sufficient to ensure that adequate reaction has occurred between the transition metal compound and the reaction product.Typically the reaction time is from 1 minute up to 100 hours depending on the procedure used. If a milling step is used for the subsequent treatment, the milling time will be dependent on the intensity of milling and in general will be from 6 up to 40 hours. However, if the subsequent treatment is effected using a liquid medium containing the transition metal compound, the time for this treatment can be from 5 minutes up to 6 hours. If the procedure of Application 8109404 is used, the reaction time may be from one second up to 100 hours and is typically at least one minute up to 20 hours.

The reaction product may also be subjected to a subsequent treatment with a Lewis Base compound. The treatment with the Lewis Base compound may be effected before, after, or at the same time as, any subsequent treatment which is effected with a transition metal compound The Lewis Base compound is preferably an organic Lewis Base compound and is, in particular, an organic Lewis Base compound which has been proposed for use in an olefine polymerisation catalyst system and which effects either the activity or stereospecificity of such a system. The treatment with the Lewis Base compound may be effected by grinding the reaction product in the presence of the Lewis Base compound. Alternatively, the reaction product may be treated with a solution of the Lewis Base compound or, if the Lewis Base compound is a liquid, with the neat Lewis Base compound.

The reaction product may be reacted simultaneously with a Lewis Base compound and a transition metal compound. This reaction may be effected by adding the Lewis Base compound and the transition metal compound separately to the reaction product and contacting the three materials under reaction conditions for the desired period of time. Alternatively, the Lewis Base compound and the transition metal compound may be'pre-mixed and the mixture added to the reaction product. The Lewis Base compound and the transition metal compound may react under the conditions of the pre-mixing and this reaction may result in a complex such as an equimolar complex of titanium tetrachloride and ethyl benzoate. The procedure used for effecting simultaneous reaction with the Lewis Base compound and the transition metal compound is similar to the procedure used for effecting reaction with only the Lewis Base compound. The subsequent treatment with the Lewis Base compound may be effected at ambient temperature or at an elevated temperature which is typically up to 1 OO"C. The reaction time may be from 1 minute up to 100 hours depending on the reaction used. If a milling step is used, the milling time will depend on the intensity of the milling and in general will be from 6 up to 40 hours. If the subsequent treatment with the Lewis Base compound is effected using a liquid medium containing the Lewis Base compound, the time for this treatment can be from 5 minutes up to 6 hours.

The amount of the Lewis Base compound which is reacted with the reaction product may be from 0.01 up to 5 millimoles of Lewis Base compound.for each gramme of the reaction product and is preferably from 0.1 up to 1.0 millimole of Lewis Base for each gramme of the reaction product.

The product obtained by the process of the present invention may be used as, or for the production of, a component of a catalyst system suitable for the polymerisation of unsaturated monomers, in particular ethylenically unsaturated hydrocarbon monomers. Since the properties nf such catalyst systems can be deleteriously effected by the presence of oxygen-containing materials, it is preferred that all stages in the process of the present invention are effected with under vacuum or in an atmosphere of an inert gas such as, for example, nitrogen or argon, which inert gas is substantially free of oxygen and oxygen-containing materials such as water vapour.

If the reaction product of the halide of M1 and the metal M2 includes a transition metal compound and/or the reaction product has been subjected to a subsequent compound, this material can be used as one component of a catalyst system for the polymerisation of ethylenically unsaturated hydrocarbon monomers.

Thus, according to a further aspect of the present invention there is provided a polymerisation catalyst comprising 1) a transition metal material which is either a) the product obtained by contacting a halide of a metal (M1) with a metal M2 which is more electro-positive than M1 at a temperature of at least 1 50 C wherein the metal M2 is, or includes, a transition metal of Group IVA, VA or VIA of the Periodic Table; or b) the product obtained by contacting a halide of a metal M', with a metal M2 which is more electro-positive than M' at a temperature of at least 300"C, wherein the metal M2 is other than a transition metal of Group IVA, VA or VIA of the Periodic Table, and thereafter treating the product of such reaction to incorporate into the reaction product ions of a transition metal of Group IVA, 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 also contain an inert material and/or a Lewis Base compound as hereinbefore described. It should be appreciated that component 1 a) may be a reaction product which has been subjected to a subsequent treatment to incorporate ions of a transition metal compound as hereinbefore described.

Component 1) of the catalyst is a solid material and preferably has a fine particle size for example particles having a maximum dimension of less than one millimetre, particularly between 5 and 400 microns and especially from 10 up to 100 microns. If component 1) includes an inert material, it is preferred that the amount of the halide of M1 used in the preparation of component 1) is such that the product of the inert halide of M' and the inert material is a freeflowing solid, and similarly the amount of M2 which is also reacted with the halide of M' and the inert material preferably should be such that the product obtained is a free-flowing solid.To obtain a free-flowing solid when using an inert material, the amount of the halide of the metal M' desirably should not exceed the amount required to cover the surface of the inert material, and this will be dependent on the specific surface area of the inert material. It is preferred to use inert materials having a high specific surface area, which is typically from 100 m2 up to 1000 m2 per gramme of the inert material. Hence, a free-flowing powder of a halide of M' supported on an inert material can be obtained in which the halide of M1 forms more than 50% by weight of the inert material supported material. Thus, depending on the specific surface area of the inert material, a free-flowing powder may be obtained which contains up to 20 millimoles of the halide of M1 for each gramme of the inert material.The amount of the at least one metal M2 desirably does not exceed the amount required to cover the surface of the inert material and preferably the amount of M2 does not significantly exceed that which will completely react with the halide of M' if a free-flowing is to be obtained. Thus, it is preferred that the amount of the at least one metal M2 is not more than two moles of M2 for each mole of the halide of M' and especially is not more than 1.1 moles for each mole of the halide of M1.

If an excess quantity of the halide of M1 and/or the at least one metal M2 is used with the inert material, this may result in the formation, as a solid mass, of the material which is used as component 1) of the catalyst. Similarly, if the halide of M' and the at least one metal M2 are reacted in the absence of an inert material, a solid mass may be obtained although, if the reaction is effected at a temperature below the melting temperature of the reaction product, a satisfactory particle-form may be obtained as the direct product of reaction. If a solid mass is obtained as the reaction product then, in order to use such a product as component 1) of the catalyst, it is desirable for this solid mass to be broken down into small particles. The solid mass can be broken down into small particles by a grinding technique for example using a rotating or vibrating ball mill.The ease of breaking down the solid mass into small particles may be increased by using a reaction mixture under conditions to form a molten product which contains two different metal ions and quench the molten material, for example of the halide of M2 with an excess of the halide of M1, to form a solid mass having a fine crystallite structure. If the reaction product is obtained as a molten material, this molten material may be subjected to a melt spraying technique to obtain a particulate solid product without having to carry out a grinding stage. Using such a melt spraying technique, the particle size of the solid product may be controlled by suitable adjustment of the melt spraying conditions.If the reaction product is a solid mass and is broken down by a grinding technique, this may be combined with a subsequent treatment with transition metal compound and/or a Lewis Base compound using procedures similar to hose hereinbefore described.

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 R1, which may be the same or different, is a hydrocarbon radical; each X1, 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 carbon 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 aluminium 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 and is particularly 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 Lewis Base compound. The Lewis Base compound is preferably an organic Lewis Base compound of the type which can be used in the production of component 1) of the catalyst 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 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 organo-phosphine, 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 803 198, 809 717, 880 998, 896509, 920 1 18, 921 954, 933 236, 940 125, 966 025, 969 074, 971 248, 1 013 363, 1 017 977, 1049723, 1122010, 1150845, 1208815, 1234657, 1324173, 1359328, 1383207, 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 prefered that one, but not both, of the groups R3 and R4 includes an acryl group. The group R3 is conveniently an optionally substituted alkyl or aryl group, for example a methyl, ethyl, or especially a phenyl, tolyl, 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 (4-methyl benzoic acid) are particularly preferred as the Lewis Base component of the catalyst system.

In addition to, or instead of, the Lewis Base compounds, the 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 der ndent on the type of materials used and the absolute concentrations of the components but if 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) for 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 component 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 preferably 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 olefine 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.

The catalyst in accordance with the present invention is of the type generally referred to as Ziegler-Natta type catalysts. As is well known, Ziegler-Natta type catalysts are susceptible to the presence of impurities in the polymerisation system. 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 asthose described in British Patent Specifications 1111 493; 1 226 659 and 1383611.

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 partial 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 532445. Polymerisation in gas phase can be effected using any technique suitable for effecting a 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. Pre-mixing of all the catalyst components can be effected in the presence of a monomer and such pre-mixing will result in at least some polymerisation of this 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 ethylne 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 1 0O'C, preferably from 50"C up to 90"C, when the polymerisation pressure does not exceed about 50 kg/cm2.

Polymerisation can be effected at any pressure which has been previously proposed for effecting the polymerisation of ethylenically unsaturated hydrocarbon 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. The particle form of component 1) may be determined by the particle form of any inert material which is used in the production of component 1). Alternatively, by appropriate treatment of the metal halide product obtained, the particle form of the transition metal component of the catalyst system may be adjusted and, in particular, an appropriate particle form, such as an essentially spherical form, may be achieved.

Various aspects of the present invention will now be described with reference to the following Examples which are illustrative of different aspects 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 oven at 1 20'C for at least one hour and purged with nitrogen before use.

EXAMPLE 1 Five grammes of silica powder (Davison 952 grade from W R Grace and Company of Maryland, USA) were placed in a large silica ampoule and the ampoule was evacuated on a vacuum line to about 10-2 torr. The ampoule was then heated to red heat (about 800'C) with a gas torch and maintained at that temperature for a sufficient time (about two minutes) for all of the moisture to be expelled. When cool, the closed tube was transferred to a dry-box under nitrogen and loaded with 7.1 grammes of zinc chloride (BDH "Analar" grade). The tube was again evacuated and the contents heated with a gas torch to about 350'C and maintained at that temperature for a time of between 5 and 10 minutes, until a free-flowing, zinc chloride coated power was obtained. The closed tube was allowed to cool and was transferred once more to the drybox and 1.3 grammes (a slight excess) of magnesium metal turnings (Fisons Grignard grade) were added under nitrogen. The tube was evacuated once more and the neck sealed by fusion using a gas-torch. The sealed tube was placed in a vertical furnace at 800-850"C for 1 6 hours. When cool, the tube was opened in a dry-box under nitrogen, giving a white to grey, free-flowing powder.

Zinc metal produced in the reaction collected as shot on top of the silica powder and for the most part this was removed easily using tweezers.

EXAMPLE 2 A. Preparation of titanium dichloride-aluminium chloride-toluene complex 24 g of aluminium powder (BDH fine powder) and 32.4 g of aluminium chloride were introduced into a two litre flask. The mixture of solids was stirred and heated to a temperature of 1 3r"C, which temperature was maintained for two hours. The mixture was then cooled, and nr e ditre of toluene was added. The flask contents were stirred and heated to reflux temperature.

24.2 9 of titanium tetrachloride in 100 cm3 of toluene were added dropwise over a period of 30 minutes. Heating was continued, at reflux temperature,for a further eight hours and the mixture was then cooled to 0 C and maintained at that temperature for two hours. The mixture was then filtered to yield a solution which was 0.08 molar with respect to titanium.

B. Preparation of catalyst component 5 9 of the product of Example 1 was suspended in 100 cm3 of toluene and the mixture was stirred without heating. A quantity of the solution obtained in stage A was added in a sufficient quantity to provide 0.1 75 millimole of titanium for each gramme of the product of Example 1.

The mixture was stirred for 20 minutes without heating and was then allowed to settle. The dark colouration of the titanium dichloride complex was-discharged from the liquid and appeared on the solid.

EXAMPLE 3 A polymerisation flask equipped with efficient stirrer and a water jacket was dried carefully and 1 litre of an aliphatic hydrocarbon fraction consisting essentially of pentamethyl-heptane isomers and having a boiling point range of about 170-185 C (hereafter "the aliphatic hydrocarbon") was introduced. The aliphatic hydrocarbon was evacuated at 60"C, purged with nitrogen and evacuated, which treatment effectively reduced the water and oxygen contents of the diluent to below 10 ppm by weight.

The aliphatic hydrocarbon was then saturated to one atmosphere pressure with purified ethylene containing less than 1 ppm by weight of oxygen and less than 1 ppm by weight of water. 10 millimoles of triethyl aluminium was introduced into the polymerisation flask. After half an hour, a sufficient quantity of the suspension obtained in stage B of Example 2 was added to provide 0.1 millimole of.titanium. The pressure in the polymerisation flask was maintained at one atmosphere by supply of the purified ethylene. After a period of one hour from the introduction of the titanium-containing suspension, the run was terminated with 5 cm3 of isopropanol. The solid was filtered, washed once with a hexane fraction and dried in a vacuum over at 80"C for an hour. The polymer yield was 20.9 grammes.

EXAMPLE 4 The procedure of Example 1 was repeated with the exception that 2.8 grammes of cadmium chloride (BDH technical grade--referred to as "dried") were used in place of the zinc chloride, and 0.9 grammes of titanium foil (an excess) were used instead of the magnesium turnings. A black free-flowing powder was obtained. Cadmium metal collected as shot on top of the silica powder and was removed as in Example 1.

EXAMPLE 5 The procedure of Example 1 was repeated using 6 grammes of silica, 7.4 grammes of zinc chloride and a mixture of 1.3 grammes of titanium foil and 0.7 grammes of magnesium turnings. A black free-flowing powder was obtained.

EXAMPLE 6 20.5 grammes of zinc chloride were added to a silica ampoule which was evacuated on a vacuum line to about 10-2 torr. The ampoule was heated until the zinc chloride had melted.

This process removed trapped air from the zinc chloride. The ampoule was cooled and the zinc chloride solidified to a glass-like mass having a volume greater than that of the molten zinc chloride. The ampoule, when cool, was closed and transferred to a glove box under nitrogen.

Four grammes of magnesium metal turnings were added. The ampoule was returned to the vacuum line, evacuated and the neck sealed by fusion. The sealed tube was placed in a vertical furnace at a temperature of between 450-550"C. When molten the ZnCl2 was greatly reduced in volume. However, due to some initial reaction having occurred, the magnesium turnings were held in their original position by a thin layer of magnesium chloride. As a consequence, further reaction was largely that of zinc chloride vapour on magnesium metal. The reaction was considered to have come to completion when no liquid zinc chloride was seen in the base of the ampoule (about 72 hours). On cooling some zinc chloride liquid condensed and collected in the base of the ampoule and this was discarded.An excess of magnesium metal was used and some of this was found at the top of the magnesium chloride plug. The displaced zinc metal formed little pellets like shot throughout the magnesium chloride plug. The product was a fine powder, white to grey in colour.

EXAMPLE 7 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) was 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 g 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 fo 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 g 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 transferred to a nitrogen filled vessel.

EXAMPLE 8 The procedure of Example 7 was repeated with the exception that, in stage A), 28.1 g 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 B) of Examples 7 and 8 is in accordance with the procedure of copending British Patent Application No. 8109404.

EXAMPLES 9 AND 10 The products of Exaples 7 and 8 were each ballmilled in the following manner.

Into a stainless steel mill of length 1 5.2 cm and diameter 7.9 cm, and fitted internally with four metal strips, were introduced 200 stainless steel balls of 1 2.7 mm diameter and 200 stainless steel balls of 1 2.7 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 either Example 7 or Example 8 was roughly crushed under nitrogen and this roughly crushed material was introduced into the mill. The mill was rotated at 120 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 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.

An aliquot of each suspension was used to polymerise ethylene as described in Example 3 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 11 7'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)t where n has a value of from 16 to 18.

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

Table Catalyst Amount Activity (mM) (9 polymer/mM Ti/hr) Example Type (a) (b) (c) 9 7 0.156 (67* (43** 10 8 0.144 125" Notes to Table (a) The product of Examples 7 and 8 respectively.

(b) Millimoles of total transition metal.

(c)" after 12 minutes polymerisation ** after one hours polymerisation.

EXAMPLE 11 Magnesium Chloride Supported on Graphite A silica ampoule was dried in an oven and transferred to a glove box where 5 9 of graphite (BDH "synthetic" grade) were added and the ampoule closed. The ampoule was transferred to the vacuum line and evacuated. The contents were heated gently to red heat using a gas torch and allowed to cool under vacuum. The cooled ampoule was closed, transferred to the glove box and 0.7 9 of anhydrous zinc chloride (BDH "Analar" grade) were added. The ampoule was then closed, transferred to the vacuum line, evacuated and gently heated with a gas torch until a free flowing powder of coated graphite was produced. The cooled tube was closed and transferred to the glove box. To this ampoule were added 0.3 9 of magnesium metal (BDH Grignard grade).

The ampoule was closed, transferred to the vacuum line, evacuated and sealed by fusion.

The sealed ampoule was transferred to a vertical furnace and heated at between 800"C jand 850"C for 16 hours. When cooled the ampoule was transferred to the glove box and cracked open. The contents were transferred to a nitrogen filled vessel.

EXAMPLE 12 The product of Example 11 was treated with titanium tetrachloride in the following manner.

The product was placed in a one dm3 flask having a heating jacket, a stirrer and a sinter base.

50 cm3 of undiluted titanium tetrachloride were added, the mixture was stirred and heated to 80"C. The mixture was stirred at 80"C for two hours and was then filtered. The solid was washed by adding 200 cm3 of a heptane fraction at ambient temperature, stirring for ten minutes without heating and then filtering. The washing procedure was repeated four times. The washed solid was then suspended in 200 cm3 of a heptane fraction.

EXAMPLE 13 The product of Example 1 2 was used as described in the the polymerisation stage of Examples 9 and 10 to effect the polymerisation of ethylene in the presence of hexene-1.

The amount of catalyst used was sufficient to provide 0.0084 mM of titanium. The average activity over a period of one hour was 1 78 9 of polymer for each nM of titanium per hour.

Claims (1)

1. A process for the production of a metal halide material comprises contacting, at a temperature of at least 150"C, a halide of a metal (M1) with at least one metal (M2) which is more electropositive than M1.

2. A process as claimed in claim 1 wherein the halide of M1 is a zinc or cadmium halide.

3. A process as claimd in claim 1 or claim 2 whrein the at least one metal M2 is selected from magnesium, aluminium, titanium and vanadium.

4. A process as claimed in any one of claims 1 to 3 wherein an essentially inert material is present.

5. A process as claimed in claim 4 wherein the essentially inert material is an inorganic oxide or carbon.

6. A process as claimed in claim 5 wherein the essentially inert material is silica, alumina, magnesia, or mixtures of two or more thereof or graphite.

7. A process as claimed in any one of claims 4 to 6 wherein the halide of M1 is pre-mixed, or reacted, with the essentially inert material at an elevated temperature, the metal M2 is added to the material obtained and contacting of the metal M2 and the mixture, or reaction product of the essentially inert material and the halide of M1 is effected at a temperature of at least 1 50 C.

8. A process aS claimed in any one of claims 1 to 7 wherein the temperature is above the melting point of the halide of M1.

9. A process as claimed in any one of claims 1 to 8 wherein the metal M2 is, or includes, aluminium and sodium chloride is also present in an amount sufficient to form a homogeneous molten phase with the aluminium chloride formed.

10. A process as claimed in any one of claims atom 9 wherein the product of contacting the halide of M1 with the metal M2 is subjected to a subsequent treatment with at least one further reagent which is a transition metal compound or a Lewis Base compound.

11. A process as claimed in claim 10 wherein the transition metal compound is titanium tetrachloride, vanadium tetrachloride, vanadyl trichloride or a titanium dichloride-aluminium chloride-arene complex comprising 1) a transition metal material which is either a) the product obtained by contacting a halide of a metal (M1) with a metal M2 which is more electro-positive than M1 at a temperature of at least 1 50 C wherein the metal M2 is, or includes, a transition metal of Group IVA, VA or VIA of the Periodic Table; or b) the product obtained by contacting a halide of a metal M1, with a metal M2 which is more electro-positive than M1 at a temperature of at least 300"C, wherein the metal M2 is other than a transition metal of Group IVA, VA or VIA of the Periodic Table, and thereafter treating the product of such reaction to incorporate into the reaction product ions of a 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.

1 3. A catalyst as claimed in claim 1 2 wherein component 1) is a transition metal material obtained by the process of any one of claims 1 to 11.

14. A catalyst as claimed in either claim 1 2 or claim 1 3 which also contains a Lewis Base compound and/or a polyene.

1 5. A polymerisation process which comprises contacting, under polymerisaton conditions, at least one ethylenically unsaturated hydrocarbon monomer with a polymerisation catalyst as claimed in any one of claims 1 2 to 14.

1 6. A process as claimed in claim 1 5 wherein the at least one ethylenically unsaturated hydrocarbon monomer is one of the formula CH2=CHR5 wherein R5 is a hydrogen atom or a hydrocarbon radical.