GB2035338A - Transition metal catalyst composition for use in olefine polymerisation - Google Patents

Abstract

A compound of a transition metal of Group IVA or VA of the Periodic Table, which compound contains at least one eta <6>-arene, is contacted with a magnesium salt of a mono- or di- carboxylic acid and optionally with a Lewis base and/or halogen compound. The transition metal compound can be a compound such as a titanium dichloride- aluminium chloride-arene complex compound. The magnesium salt may be magnesium acetate, magnesium trifluoroacetate, magnesium benzoate or magnesium oxalate. The product is used for the polymerisation of olefines, preferably in the presence of an organo- metallic compound such as an organo- aluminium compound.

Description

SPECIFICATION Production of transition metal composition The present invention relates to the treatment of compounds of transistion metals and to the use of the treated compounds as components of catalysts for the polymerisation of ethylenically unsaturated hydrocarbon monomers.

According to the present invention a compound of a transition metal of Group IVA or VA of the Periodic Table, which compound contains at least one -.arene group, is contacted with at least one magnesium salt of a moncarboxylic acid or of a dicarboxylic acid.

For convenience hereafter, a magnesium salt of a monocarboxylic acid or of a dicarboxylic acid will be referred to simply as "a magnesium salt".

The proportions of the materials which are used may be varied considerably and a molar excess of either material, especially the magnesium salt, may be used, for example from 0.01 up to 100, especially from 0.1 up to 1.0, moles of the transition metal compound for each mole of the magnesium salt.

The transition metal is preferably a metal of Group IVA and is particularly titanium. The transition metal compound may contain only the 6-arene group, or may also contain other groupings such as halogen atoms, and the compounds may be in the form of a complex with other compounds. In the transition metal compound the valency of the metal may be zero or any valency wherein the transition metal is able to form a stable compound containing at least one rj6-arene group. Useful effects have been obtained using, as the transition metal compound, a titanium dichloride-aluminium chloride-arene complex compound where the arene group is any suitable arene, for example benzene, toluene or durene (1 ,2,4,5-tetramethylbenzene).

Alternatively, the transition metal compound may be titanium (0) ditoluene. The term "arene" as used herein is used to mean a compound containing a six-member hydrocarbyl ring which ring contans a completely delocalised double-bond system. It will be appreciated that the term arene as used includes not only benzene, toluene and durene, but also xylene, hexamethylbenzene and substituted derivates thereof such as chlorobenzene.

The magnesium salt is conveniently an an hydros salt, for exaple a material represented by the formula (A) or the formula (B) in the accompanying formula drawings wherein R is a hydrogen atom, a hydrocarbyl or a halohydrocarbyl group; and n isO, or an integer of from 1 up to 6.

The group R may be an alkyl group, for example an alkyl group containing 1 up to 6 carbon atoms, an aryl group such as phenyl or a mixed alkyl-aryl group such as a tolyl or benzyl group. The group R may contain one or more halogen atoms as in the trifuluoromethyl group. The value of n is conveniently zero. The magnesium salt is conveniently magnesium acetate, magnesium trifluoroacetate, magnesium benzoate or magnesium oxalate.

The magnesium salts may be prepared by the reaction of a solution, in a hydrocarbon medium, of a magnesium hydrocarbyl compound, for example magnesium dibutyl, with the appropriate carboxylic acid.

Alternatively, magnesium carbonate may be reacted with the appropriate carboxylic acid in an aqueous medium, for which the magnesium salt formed is recovered by crystallisation or evaporation to dryness, if desired followed by heating under reduced pressure to isolate the anhydrous salt. If desired the magnesium salt may be recrystallised from a non-aqueous medium, for example methanol or may be heated to a temperature of at least 100,0 under a reduced pressure typically less than 2 mm of mercury.

The magnesium salt is typically a solid particulate compound which preferably has a high surface area and it will be appreciated that some magnesium salts inherently have such a high surface area whereas with other compounds it is necessary to grind, or otherwise comminute, the solid compound in order to achieve a satisfactory high surface area. It is preferred that the surface area of such solid compounds is at least 1 m2/g and it is particularly preferred that the area is at least 10 m2/g and especially 30 m2/g.

The contacting of the magnesium salt with the transition metal compound may be effected in the presence of a halogen-containing compound which may be either an organic or inorganic halogenating compound.

Alternatively, the magnesium salt is contacted with the transition metal compound and the product obtained is then contacted with a halogen-containing compound which may be either an organic or inorganic halogenating compound. Suitable halogen-containing compounds of this type include hydrogen chloride, titanium tetrachloride, toluoyl chloride, silicon tetrachloride, carbon tetrachloride, carbon tetrabromide, chlorine, bromine, aluminium chloride and ammonium hexafluorosilicate. The amount of the halogencontaining compound which is used is preferably at least 0.10 mole per g atom of transition metal which is present in the transition metal compound, and is very preferably at least 0.5 mole per g atom of the transition metal compound.Very conveniently a molar excess of the halogen-containing compound is used and any excess of the halogen-containing compound which remains after completion of the treatment may be removed using any suitable technique such as filtration and/orwashing with an inert liquid. The contacting with the halogen-containing compound is conveniently effected at a temperature of from 0 C to 1 50 C, typically from 25 c up to 80"C, for a time of from 5 minutes up to 24 hours, typically 0.5 up to 2 hours.

In addition to, or as an alternative to, the contacting with the halogen-containing compound, the contacting of the magnesium salt and the transition metal compound may be effected in the presence of an organic Lewis Base compound. Alternatively, the magnesium salt is contacted with the transition metal compound, in the presence of absence of the halogen-containing compound, and the product obtained is then contacted with an organic Lewis Base compound, in the presence or absence of the halogen-containing compound. The contacting with the organic Lewis Base compound is conveniently effected at a temperature in the range from 0 C up to 1 00'C, typically from 20"C up to 60"C, for a time of from one to 50 hours, typically 5 up to 20 hours.The organic Lewis Base compound can be any Lewis Base compound which is effective to alter the activity and/or stereo-specificity of a Ziegler catalyst system. A wide range of organic Lewis Base compounds have been proposed for use as components of Ziegler catalyst systems, and any such compounds may be used. Thus, the organic Lewis Base compound may be an ether; an ester; a ketone; an alcohol; a sulphur-containing analogue of ethers, esters, ketones and alcohols; a sulphone; a sulphonamide; a fused ring compound containing a heterocyclic sulphur atom; an organo-silicon compound; an amide; urea or thiourea; an amine, which term is used to include alkanolamines, cyclic amines and diamines; or an organo-phosphorus compound such as an organo-phosphine, an organo-phosphine oxide, an organo-phosphite or an organo-phosphate.The use of organic Lewis Base compounds is disclosed inter alia in British Patent Specifications 803, 717,880 998,896 998,896509,920118,921 954,933236,940 125, 966025,969074,971 248, 1 013363, 1 017977, 1 049723, 1122010, 150 845,1 1 815,1 234657,1 324 173, 1 359 328, 1 383 207, 1 423 658, 1 423 659 and 1 423 660 and Belgian Patent Specification 693 551. Suitable sulphones, sulphonamides, and fused ring compounds containing a heterocyclic sulphur atom are disclosed in published German Patent application 2 600 552.If an organic Lewis Base compound is included in the system, the proportion of the organic Lewis Base compound is preferably at least 0.1 mole per g atom of the transition metal which is present in the transition metal compound and very preferably not more than 5 moles of the organic Lewis Base compound per g atom of transition metal.

The contacting of the transition metal compound with the magnesium salt is conveniently effected by contacting the magnesium salt with a solution of the transition metal compound in a hydrocarbon or other inert diluent. The contacting may be effected by stirring a suspension or solution of the magnesium salt in a suitable inert diluent with a solution of the transition metal compound, or may be effected by griding the magnesium salt in then presence of the transition metal compound, which may be in the solid form or in solution in a suitable inert liquid.However, it will be appreciated that if the magnesium salt is a solid particulate material, such a solid material may be subjected to a grinding step either before or after it has been contacted with the transition metal compound, and it is not necessary to effect grinding of such a solid material in the presence of the transition metal compound.

The contacting of the transition metal compound with the magnesium salt may be effected at any suitable temperature but, since some of the transition metal compounds are thermally unstable, when using such compounds it is preferred to use temperatures of ambient temperature or below. Thus, depending on the transition metal compound, the temperature of contacting may be as low as -100 C, for example -78 C, although using the titanium dichloride-aluminium chloride-arene complex compounds, temperatures in the range ambient up to 100"C are typically used.A convenient temperature for the contacting is in the range 0 C up to 80"C. The solvent used for the dissolution of the transition metal compound may be any suitable inert liquid in which the compound is stable and is conveniently an aromatic liquid since many of the transition metal compounds have a greater solubility in such diluents.

If the magnesium salt is a solid particulate material which is subjected to a grinding step, this can be effected in any known manner for example in a rotating ball mill or in a vibrating ball mill. The time of grinding will be dependent on a number of factors including the nature of the material to be ground, the particular size desired in the ground product and the intensity of the grinding. In general a time of from 1 hour up to 100 hours is sufficient to effect the requisite comminution of the solid material. The milling can be effected at any desired temperature such as 0,C up to 40on, conveniently at ambient temperature, but it will, be appreciated that a lower temperature may be used if the grinding is being effected in the presence of a thermally unstable transition metal compound.

Although some of the transition metal compounds are thermally unstable and have to be stored at a low temperature, some products of contacting the transition metal compound with the magnesium salt have an improved stability and can be stored at ambient temperature without appreciable deterioration. Thus, if the product of contacting the transition metal compound with the magnesium salt is a solid particulate material, this product may be stored as a dry solid or as a suspension in a suitable inert liquid.

The product of contacting the transition metal compound with the magnesium salt can be used, either alone or together with other compounds such as the organic compound of a non-transition metal of Groups IA and IIA or of aluminium, to polymerise ethylenically unsaturated hydrocarbon monomers.

Thus, as a further aspect of the present invention there is provided a catalyst suitable for the polymerisation of ethylenically unsaturated hydrocarbon monomers, which catalyst contains a transition metal component which is the product of contacting a transition metal compound of a metal of Group IVA or VA of the Periodic Table,which compound contains at least one 6-arene, with at least one magnesium salt (as hereinbefore defined).

The catalyst may be a single component catalyst system which consists solely of the transition metal-containing component prepared in the manner hereinbefore described, but the catalyst may include, as a second component, at least one organo-metallic compound of aluminium or of a non-transition metal of Group IIA of the Periodic Table or a complex of an organo-metallic compound of a non-transition metal of Group IA or IIA of the Periodic Table and an organo-aluminium compound.

The second component of the catalyst system can be a Grignard reagent which is substantially ether free or a compound of the type Mg(C4H9)2. Alternatively, the second component can be a complex of an organo-metallic compound of a non-transition metal of Group IA or IIA with an organo-aluminium compound, for example Mg[Al(C2H5)4]2 or lithium aluminium tetraalkyl. It is preferred that the second component is an organo-aluminium compound such as a bis(dialkyl aluminium oxy)alkane, a bis(dialkyl auminium)oxide, an aluminium hydrocarbyl sulphate, an aluminium hydrocarbyloxyhydrocarbyl or particularly an aluminium trihydrocarbyl or dihydrocarbyl aluminium halide or hydride. We particularly prefer to use either an aluminium trialkyl such as aluminium triethyl or an aluminium dialkyl halide such as diethyl aluminium chloride.We particularly prefer that the second component is a halogen-free material for example an aluminium trialkyl.

In addition to the first and second components, the catalyst may also contain other components, for example organic Lewis Base compounds. The organic Lewis Base compound may be the same as, or different from, the organic Lewis Base compound with which the magnesium salt and the transition metal compound are optionally treated. Thus, the organic Lewis Base compound which may be used as a possible third component of the catalyst may be any Lewis Base compound of the type previously described. The optional Lewis Base compound may be incorporated into the catalyst system as a complex with the organo-metallic component of the catalyst. Suitable complexes of the organic Lewis Base compound and the organo-metallic compound include complexes of aluminium trialkyl with esters and in particular with aromatic esters such as ethyl benzoate or ethyl anisate.

In addition to, or instead of, the organic Lewis Base compound, the catalyst may also contain a substituted or unsubstituted polyene. The polyene may be an acyclic polyene such as 3-methylheptatriene-1 ,4,6 or a cyclic polyene such as cyclooctatriene, cyclooctatetraene or cycloheptatriene or may be a derivative of such cyclic polyens, for exaple the alkyl- or alkoxy-substituted polyenes, tropylium salts or complexes, tropolone or tropone.

The proportions of the catalyst components can be varied quite widely depending on the particular materials used and the absolute concentrations of the components. The proportions will also be dependent on the monomer which is to be polymerised. However, if the catalyst system includes components in addition to the transition metal component, then these may be present in the conventional proportions for Ziegler catalyst systems. More specifically, for each gramme atom of the transition metal which is present in the product of contacting the transition metal compound with the magnesium salt, there should be present at least 0.05 and preferably at least 1 mole of the organo-metallic compound which is the second component of the catalyst.However, in general it is preferred to use larger quantities of the organo-metallic component and the proportion of this compound may be as high as 100 moles for each gramme atom of the transition metal compound. However, in general we prefer to use smaller proportions of the organo-metallic compounds, for example not more than 25, and particularly not more than 10 moles, of the second component for each gramme atom of the transition metal. If a Lewis Base component is also present in the catalyst system, the number of moles of the Lewis Base compound should not be greater than the number of moles of the organo-metallic compound which is the second component of the catalyst. If the catalyst includes a polyene, then the molar proportion of the polyene is preferably less than the molar proportion of the second component.Preferably for each mole of the second component there is present from 0.05 up to 0.5 particularly from 0.1 up to 0.2 mole of the polyene.

The catalyst of the present invention can be used to polymerise ethylenically unsaturated hydrocarbon monomers by contacting at least one such monomer with a catalyst of the type hereinbefore described.

More specifically there is provided a process for the production of a hydrocarbon polymer wherein at least one ethylenically unsaturated hydrocarbon monomer is contacted with a polymerisation catalyst of the type hereinbefore described.

The ethylenically unsaturated hydrocarbon monomer may be a mono-olefine and may be any which is capable of being polymerised using a Ziegler catalyst system. Thus, monomers which can be polymeised by the process of the present invention may be mono-alpha-olefines containing up to 18 carbon atoms, for example butene-1 and 4-methylpentene-1 and particularly ethylene and propylene. If desired the olefines, particularly ethylene and propylene, may be copolymerised together, for example using a sequential polymerisation technique such as is described in British Patent Specifications 970 478, 970 479 and 1 014944.

The monomer may, alternatively, be a diene or polyene such as, for example, butadiene.

The type of catalyst for the polymerisation will be dependent on monomer being polymerised. If ethylene or a mixture containing ethylene is to be polymerised, the catalyst can consist solely of the product of contacting the transition metal compound with the magnesium salt. However, it is preferred, particularly if the monomer to be polymerised is propylene or a higher olefine, that is one containing 4 or more carbon atoms, that the catalyst system includes a second component which is an organo-metallic compound of aluminium or of a non-transition metal of Group IIA of the Periodic Table, our a complex of a non-transition metal of Group IA or IIA of the Periodic Table and an organo-aluminium compound. For the polymerisation of propylene and higher olefines, the catalyst system may also include an organic Lewis Base compound.

We have found that the process of the present invention can be used to obtain a high yield of a polymer relative to the amount of the catalyst used.

It is preferred to use monomers (and diluents when required) which have a high degree of purity, for example a monomer containing 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 1111 493, 1 226 659 and 1 383 611.

Polymerisation can be carried out in 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 escess liquid monomer or in the gaseous phase.

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 all the catalyst components may be mixed together before being introduced into the polymerisation reactor.

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, it is conveniently used in an amount of from 0.01 up to 5.0%, particularly from 0.10 up to 2.0%, molar relative to the monomer. The amount of chain transfer agent will be dependent on the polymerisation conditions, especially the temperature, which is typically in the range from 1 5"C up to 1 00'C.

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 were effected under an atmosphere of nitrogen unless otherwise indicated.

A) Preparation of titanium dichioride-aluminium chloride-benzene complex 51 grammes of aluminium powder (BDH fine powder) and 80 grammes of anydrous aluminium chloride were introduced into a two-litre, three-necked flask and the mixture of solids was heated at 130"C for 0.5 hour. The mixture was then allowed to cool. 500 ml of benzene was added and then 33.3 grammes of titanium tetrachloride was added with stirring. The mixture was refluxed for 20 hours and then allowed to cool. The cool solution was filtered into one litre of an isoparaffin fraction having a boiling temperature range of 97"C to 103"C (hereafter this fraction will be identified simply as "heptane"), and this mixture was cooled to -1 0"C and maintained at this temperature for 24 hours.The supernatant liquid was decanted from the purple solid which had been formed. The solid was washed four times using one litre of heptane for each wash, and then was dried under reduced pressure (1 mm of mercury) at ambient temperature. The solid was then dissolved in toluene at ambient temperature to give a solution of concentration 0.098 M.

B) Preparation of titanium dichloride-aluminium chloride-benzene complex The initial stages were as described in Preparation A) but the preparation was terminated after refluxing for 20 hours, cooling and filtering. The solid was not isolated from the filtrate, the product was used as a solution in benzene, which was diluted with further benzene before being used. Analysis of the solution showed itto contain titanium and aluminium in an atomic ratio of 1 to 2.

C) Preparation oftitanium dichloride-aluminium chloride-benzene complex The procedure described in Preparation A) was repeated with the exception that the solid product was not dissolved in toluene as the last step but was stored in the dark as the solid product.

D) Preparation of anhydrous magnesium acetate Dibutyl magnesium (obtained from the Lithium Corporation of America) was used as a 0.63 M solution in an isoparaffin fraction, essentially all of which had a boiling temperature in the range I 170C to 135"C. cm3 of this solution was diluted with 100 cm3 of dry heptane. The solution was vigorously stirred and to the stirred solution a solution of glacial acetic acid (7.21 cm3) in heptane (300 cm3) was added dropwise from a funnel over a period of 0.75 hours. A white precipitate formed. At the end of the addition, the reaction mixture was stirred for a further 0.5 hour and was then filtered. The solid residue was washed once with heptane (100 cm3) and was then suspended in heptane (100 cm3).

E) Preparation of anhydrous magnesium benzoate Benzoic acid (122 g) was added to stirred distilled water (300 cm3) and the mixture heated to reflux temperature in air to give a clear solution. Magnesium carbonate was added in powder form to give a slight excess and thus causing the formation of a light suspension. A small additional quantity of benzoic acid was then added dropwise to the mixture until the suspension just dissolved. The solution was cooled and the crystalline precipitate that formed was filtered off and air-dried at ambient temperature and pressure by sucking air through the filtrate. To remove excess benzoic acid, the precipitate was then washed six times using 200 cm3 of diethyl ether for each wash. 20 g portions of the solid were dissolved in refluxing methanol, and recrystallised from the cooled solution. The recrystallised solid was washed three times with 100 cm3 of diethyl ether for each wash and pumped dry at ambient temperature and pressure. The dry solid was heated at 140"C for 6 hours at a pressure of 0.1 mm of mercury, and the product was stored in a sealed vessel under nitrogen until used.

F) Preparation of anhydrous magnesium trifluoroacetate Aslurry of magnesium carbonate (84.3 g) and distilled water (500 cm3) was added slowly to a stirred solution of trifluoroacetic acid (155 cm3) in distilled water (100 cm3) in air at ambient temperature. The time of addition was 45 minutes. A clear yellowish solution formed and, since this was slightly acid, a small amount of MgCO3 was added in powder form until the solution was neutral. The solution was then filtered and evaporated to dryness to give a glassy solid which was broken up and ground with a mortar and pestle in air. A portion of this product was heated under vacuum (0.2 mm of mercury) at 11 5"C for 3 hours. The heated product was then ground up again in air and reheated under vacuum (0.2 mm of mercury) at 1200C for 1 hour. The product was stored in a sealed vessel under nitrogen until used.

Example 1 Hydrated magnesium acetate [(CH3C02)2Mg.4H20 - 'Analar' grade obtained from BDH Chemicals Limited, Poole, England] was heated at 120"C for 16 hours in a vacuum oven at a pressure of 0.2 mm of mercury to gtve anhydrous magnesium acetate which was stored in a sealed vessel under nitrogen until used. 50 cm3 of the toluene solution obtained in Preparation A) was added dropwise over a period of 5 minutes to the anhydrous magnesium acetate (1.72 g) stirred in a Schlenk tube under an atmosphere of nitrogen. The resulting mixture was stirred for a further 0.5 hour and then heated, with stirring, at 70"C for 5 minutes. The supernatant liquid was then decanted and the residue was washed three times with dry degassed heptane (70 cm3). The solid residue was suspended in heptane (80 cm3).A 5 cm3 portion of the suspension was added to an excess of 3 N sulphuric acid and the titanium content of this was determined by titration with 0.05 N ceric sulphate solution, using a 2% (wt/vol) solution of diphenylamine in concentrated sulphuric acid as indicator. The remaining 75 cm3 of the suspension were used as a polymerisation catalyst.

Example 2 The same procedure as that described in Example 1 was employed except that the amount of anhydrous magnesium acetate was 6.3 g and the titanium compound was 46 cm3 of a 0.385 M solution obtained by diluting the product of Preparation B). The solid obtained was washed three times with dry toluene (100 cm3 for each wash) and suspended in 80 cm3 of heptane. Titration of the final stirred suspension gave a concentration of 0.095 milligramme atoms of titanium/cm3.

Example 3 The same procedure as that described in Example 2 was employed except that 4.75 g of magnesium acetate and 75 cm3 of a 0.18 M solution obtained from the Preparation B) solution were used. The resulting suspension was stirred at ambient temperature (20-25"C) for 30 minutes, and then at 60"C for 30 minutes before filtering and washing. Titration of the final stirred suspension gave a concentration of 0.105 milligramme atoms of titanium/cm3.

Example 4 The same procedure as that described in Example 2 was employed except that 6.8 g of anhydrous magnesium acetate and 50 cm3 of a 0.36 M solution obtained from the Preparation B) solution were used.

The suspension of the solid in heptane was left to stand for four days. Analysis of the stirred suspension showed it to contain 0.15 milligramme atoms of titanium/cm3.

Comparative Example A 2.0 cm3 of titanium tetrachloride was added to a stirred suspension of an hydrous magnesium acetate (8.4 g) in toluene (100 cm3) and the resulting suspension was stirred at ambient temperature for 45 minutes.

The mixture was then stirred and heated at 60"C for 15 minutes. After cooling, the residue was collected by filtration and washed three times with dry toluene (80 cm3 for each wash). The solid ws then suspended in beptane (80 cm3). By analysis, the suspension was found to contain 0.056 milligrame atoms of titanium/cm3.

Example 5 The same procedure as that described in Example 2 was employed except that 6.0 g of anhydrous magnesium acetate and 110.8cm3 of a 0.152 M solution obtained from the Preparation B) solution were used. The resulting mixutre was stirred first at ambient temperature for 0.5 hour and then at 70"C for 1 hour before filtration and washing. By analysis, the final stirred suspension contained 0.0435 milligramme atoms of titanium/cm3.

Example 6 The same procedure as that described in Example 2 was employed except that 9.38 g of magnesium acetate and 132 cm3 of a 0.208 M solution obtained from the preparation B) solution were used. The resulting suspension was stirred at ambient temperature for 0.5 hour and then at 70"C for 0.5 hour before filtration and washing. Titration of the final stirred suspension gave a concentration of 0.045 milligram atoms of titanium/cm3.

Example 7 Into a Megapact Vibration Mill (manufactured by Pilamec, Gloucestershire, England) of internal diameter 3.8 cm and length 56 cm were introduced 110 stainless steel balls of 12.7 mm diameter and 1700 stainless steel balls of 6.35 mm diameter. The mill was sealed, evacuated to 0.2 mm mercury and purged with nitrogen to give a nitrogen atmosphere in the mill. 27.1 g of the solid product of Preparation C) and 21.0 g of anhydrous magnesium acetate (21.0 g) were mixed together in a reaction vessel by shaking under nitrogen and the mixture was introduced into the mill under nitrogen. Water at ambient temperature (20"C) was circulated through the jacket of the mill. Milling was effected for a period of 16 hours using a frequency of 2800 oscillations per minute and an amplitude of 2 mm.At the end of 16 hours, heptane (200 cm3) was introduced into the mill under nitrogen and the mill was emptied whilst vibrating with a nitrogen stream passing through it. From the stirred suspension obtained, a sample was analysed for titanium by the hydrogen peroxide method and gave a concentration of 0.040 milligramme atoms of titanium/cm3; Example 8 A 10 cm3 sample of the stirred suspension of the product of Example 7 was filtered and the filtrate was washed three times with toluene using 100 cm3 for each wash, and then suspended in 80 cm3 of heptane. A sample of this stirred suspension was found to contain 0.028 milligramme atoms oftitanium/cm3.

Example 9 The same procedure as that described in Example 2 was used except that 57.5 cm3 of a 0.26 M solution obtained from the Preparation B) solution and 5.31 g of an hydros magnesium acetate were used, the mixture was stirred at ambient temperature (20-25"C) for 1 hour and at 70"C for 1 hour. This solid, after washing with toluene, was suspended in 40 cm3 of heptane and the mixture was stirred.3.76 of or ethyl benzoate (70% molar based on the magnesium present in the solid) was added and the mixture stirred overnight (about 16 hours). The mixture was filtered and the residue obtained was washed three times with heptane using 100 cm3 for each wash. To the washed, solid residue was added 40 cm3 of titanium tetrachloride and the resulting mixture was stirred at 80"C for 2 hours.The mixture was then filtered, the residue was washed three times with 80 cm3 of heptane for each wash and finally suspended in 100 cm3 of heptane. Analysis of a sample of the suspension showed itto contain 0.144 milligramme atoms of titanium/cm3.

Example 10 The procedure of Example 2 was repeated using 75.7 cm3 of a 0.26 M solution obtained from the Preparation B) solution and 6.98 g of anhydrous magnesium acetate. The mixture was stirred at ambient temperature (20-25"C) for 0.5 hour and at 70"C for 0.5 hour. After washing with toluene, the solid was suspended in 80 cm3 of heptane, the mixture was stired and treated, for 0.5 hour, with hydrogen chloride gas at a rate sufficient to keep the liquid saturated with hydrogen chloride at ambient temperature (20-25"C). The mixture was then filtered and the residue was washed once with toluene (50 cm3) and twice with heptane using 50 cm3 for each wash and then suspended in 80 cm3 of heptane. Analysis of the stirred suspension gave 0.916 milligramme atoms of titanium/cm3.

Example ii A portion of the magnesium acetate suspension of Preparation D), containing 28.4 mM of magnesium acetate, was filtered and the solid residue was suspended in 50 cm3 of benzene. The resulting suspension was vigorously stirred and then treated dropwise with 84.1 cm3 of a 0.21 M solution obtained from the solution of Preparation B) added over a period of 15 minutes. A dark precipitate rapidly formed and the mixture was stirred for 0.5 hour at ambient temperature (20-25"C) and was then filtered. The filtrate obtained was slightly red-coloured showing that the Solution B) had been used in slight excess. The solid residue was washed three times with toluene using 100 cm3 for each wash and was then suspended in 80 cm3 of heptane.

Analysis of a sample of the suspension showed it to contain 1.51 milligramme atoms oftitanium/cm3.

Example 12 9.32 g of magnesium benzoate product of Preparation E) was treated at ambient temperature with 98.0 cm3 of a 0.23 M solution obtained from the solution of Preparation B). The mixture was stirred at ambient temperature (20-25"C) for 30 minutes and then filtered. The solid residue obtained was washed twice with toluene using 100 cm3 for each wash and then suspended in 100 cm3 of heptane. 1 cm3 of this suspension contained 0.143 milligramme atoms of titanium.

Example 13 75 cm3 of a 0.18 M solution obtained from the solution of Preparation B) was added to 8.45 g of the magnesium trifluoroacetate product of Preparation F). The resulting mixture was stirred at ambient temperature for 30 minutes and then at 65"C for 45 minutes. The solution decolorised to pale orange and a gummy solid formed. The liquid phase was decanted and the gum was washed three times with toluene using 100 cm3 for each wash. The solid was stirred with a glass rod and the resulting powder was suspended in 70 cm3 of heptane. The suspension was found to have a concentration of 0.160 milligramme atoms of titanium/cm3.

Example 14 Magnesium oxalate Mg(04C2).2H20 (supplied by BDH Chemicals Limited, Poole, England) was dried in a vacuum oven at a pressure of 0.2 mm of mercury at 125"C for 16 hours and stored in a sealed vessel under nitrogen until used. 5.85 g of the dried solid was treated, under nitrogen, with 115 cm3 of a 0.18 M solution obtained from the solution of Preparation B). The mixture was stirred at ambient temperature (20-25"C) for 1 hour and at 90"C for 30 minutes. During this time the supernatant solution became an intense yellow colour After cooling, the mixture was filtered and the residue obtained was washed seven times with toluene using 80 cm3 for each wash.The washings changed in colour from deep yellow for the first to pale yellow for the last one. 80 cm3 of heptane was then added to the solid residue and analysis of a sample of the suspension, found 0.0683 milligramme atoms of titanium/cm3.

Example 15 A sample of magnesium oxalate heated as in Example 14 was then further heated under vacuum (0.2 mm of mercury) at 230C for 36 hours and stored in a sealed vessel under nitrogen until used. 5.60 g of the product obtained was treated, under nitrogen, with 111 cm3 of a 0.18 M solution obtained from the solution od Preparation B) and the mixture was stirred at ambient temperature for 1 hour and then at 70"C for 1.5 hours. After cooling, supernatant solution, which was still purple in colour, was decanted and the residue was washed six times with toluene using 80 cm3 for each wash.The washings changed in colour from orange-red in the first to very pale yellow in the last wash. 80 cm3 of heptane was then added to the residue and analysis of the resulting suspension showed it to contain 0.0290 milligramme atoms of titanium/cm3.

Example 16 Magnesium oxalate Mg(04C2).2H20 (from BDH Chemicals Limited) was placed in an open-ended glass tube under a nitrogen stream and the tube was heated in a furnace at 300"C for 3.5 hours. After cooling, 5.48 g of the heated solid was treated, under nitrogen, with 108 cm3 of a 0.18 M solution obtained from the solution of Preparation B) and the resulting mixture was stirred at ambient temperature (20-25"C) for 1 hour and then at 70"C for 1.5 hours. The mixture was allowed to cool and was filtered. The solid was washed four times with toluene using 80 cm3 for each wash; the final washing being colourless. The residue was then suspended in 80 cm3 of heptane and analysis of the suspension found 0.0236 milligramme atoms of titanium/cm3.

Examples 17 to 35 Some of the products of Examples 1 to 16 were used to polymerise propylene. 500 ml of dry heptane which was contained in a one-litre flask and in which was dissolved 10 millimoles of an organo-aluminium compound was saturated with propylene at atmospheric pressure and 60on. The contents of the flask were stirred and the product of one of Examples 1 to 16 was added in a quantity sufficient to provide the amount of titanium compound indicated in Table 1. In all the Examples, unless otherwise stated, the product of one of Examples 1 to 16 was allowed to stand overnight (about 16 hours) after being prepared and before being used in the polymerisation process.

The pressure and temperature were maintained at atmospheric pressure and 60"C respectively and the amount of propylene being fed into the flask was monitored. After a period of time as indicated in Table 1, the supply of monomer was stopped and polymerisation was terminated by the addition of about 30 ml of isopropanol. The heptane insoluble polymer was separated off by filtration and, when the monomer was propylene, the heptane soluble polymer was isolated by evaporation of the solvent. The polymers (soluble and insoluble) were dried at 120"C under nitrogen at a pressure of 0.1 mm of mercury.

Further details of the procedure used, and the results obtained, are set out in Table 1.

Ti compt Organo Al EA Time Yield Activity Wt% Ex Type Amount Type (mM) (hr) (e) (f) Insol (a) (mM) (c) (d) (g) (b) 17 1 2.0 TEA NIL 2.4 37.3 7.7 70 18 2 2.0 TEA NIL 2.2 67.5 15.3 68 19 3 2.0 TEA NIL 2.0 89.9 22.5 65 20 4 2.0 TEA NIL 1.5 42.1 13.7 61 21 7 1.1 TEA NIL 2.0 34.7 15.8 49 22 8 1.4 TEA NIL 2.0 25.8 9.2 48 23 2 2.0 TEA 3.7 2.0 6.0 1.5 ND 24 2* 2.0 TEA 0.5 2.2 21.9 4.8 65 25 2* 2.0 TEA 1.0 2.3 29.9 6.5 70 26 9 2.9 TEA NIL 2.0 27.3 4.7 69 27 9 2.8 TEA 3.7 2.0 16.5 2.9 71 28 10 2.4 TEA NIL 2.0 101.7 21.4 55 29 12 2.0 TEA NIL 2.1 82.7 20.0 34 30 12 2.0 DEAC NIL 3.7 18.1 2.4 18 31 13 2.0 TEA NIL 2.0 54.0 13.5 52 32 13** 2.0 TEA NIL 2.0 53.0 13.3 57 33 14 2.0 TEA NIL 2.0 8.6 2.15 57 34 15 2.0 TEA NIL 2.0 23.2 5.8 65 35 16 1.0 TEA NIL 2.0 9.6 4.8 65 Notes to Table 1 (a) The number indicates the Example in which the preparation is described.

*The product of Example 2 was alowed to stand for 5 days at ambient temperature before being used.

**The product of Example 12 was allowed to stand for 3 days at ambient temperature before being used.

(b) The amount is expressed in terms of the titanium content of the product, as determined by analysis.

(c) TEA is triethyl aluminimu DEAC is diethyl aluminium chloride.

(d) EA is ethyl anisate. In the Examples in which ethyl anisate was present, the triethyl aluminium, in 40 cm3 of n-heptane, was mixed with the ethyl anisate at ambient temperature and the mixture was then added to the polymerisation vessel.

(e) Yield of total (soluble and insoluble) polymer in grammes.

(f) Activity is expressed as g of polymer per milligramme atom of titanium for each atmosphere of pressure and hour of polymerisation, as averaged over the polymerisation time.

(g) (Wt of Insoluble polymer) x 100 (Wt of Soluble polymer + Wt of Insoluble polymer) Examples 36 and 37 The procedure of Examples 17 to 35 was repeated using ethylene as the monomer and the products of Example 6 or Example 11 as the titanium component. The proportion of heptane insoluble polymer formed was not determined. The organo-aluminium compound was triethyl aluminium in all cases. Ethyl anisate was not present in the catalyst system. For comparative purposes, polymerisation was also effected with the product of Comparative Example A and also using a solution (0.098 M) of the product of Preparation A). The results are given in Table 2.

TABLE 2 Ex Ti compt or Time Yield Activity Comp Type Amount (hr) (e) (f) Ex (a)(h) 36 6 0.81 2.0 113 42.2 37 11 3.01 1.0 60 19.9 B B A 2.0 1.4 30 10.7 C PA 2.0 4.0 ND 0.1 Notes to Table 2 Notes (a), (e) and (f) are as defined in Notes to Table 1.

(h) A is the product of Comparative Example A PA is the product of Preparation A) and the polymerisation was effected using toluene as the diluent.

Example 36 The procedure of Examples 17 to 35 was repeated using the product of Example 5 and an elevated pressure. Two litres of heptane were placed in a five-litre stainless steel vessel and 10 millimoles of triethylaluminium was added. Propylene was added to saturate the heptane at atmospheric pressure (1 Kg/cm2 absolute pressure). Sufficient of the product of Example 5 was added to provide 2.0 millimoles of the titanium compound. Propylene was then added to raise the monomer pressure to 100 psi (6.8 Kg/cm2 absolute pressure) and the temperature was controlled at 77"C. After 2 hours the catalyst was destroyed with isopropanol (100 cm3) and the suspension of soluble and insoluble polymer was isolated and recovered as described in Examples 16 to 34. The yield of polymer was 696.3 g, which corresponded to an activity (as defined in Note (f) of Table 1) of 25.6. The proportion of heptane insoluble polymer was 46% by weight.

Claims (10)

1. A process comprising contacting a compound of a transition metal of Group IVA or VA of the Periodic Table, which compound contains at least 6-arene group, with at least one magnesium salt of a monocarboxylic acid or of a dicarboxylic acid.

2. A process as claimed in claim 1 wherein from 0.1 up to 1.0 mole of the transition metal compound is contacted with each mole of the magnesium salt.

3. A process as claimed in claim 1 or claim 2 wherein the transition metal compound is a titanium dichloride-aluminium chloride-arene complex compound.

4. A process as claimed in any one of claims 1 to 3 wherein the magnesium salt is magnesium acetate, magnesium trifluoroacetate, magnesium benzoate or magnesium oxalate.

5. The process of any one of claims 1 to 4 wherein a halogen-containing compound is also present.

6. The process of any one of claims 1 to 5 wherein an organic Lewis Base compound is also present.

7. The process of any one of claims 1 to 6 wherein the contacting is effected by grinding.

8. An olefin polymerisation catalyst comprising a transition metal component which is the product of the process of any one of claims 1 to 7 and an organo-metallic compound of aluminium, or of a non-transition metal of Group IIA of the Periodic Table or a complex of an organo-metallic compound of a non-transition metal of Group IA or IIA of the Periodic Table and an organo-aluminium compound.

9. A catalyst as claimed in claim 8 wherein the organo-metallic compound of aluminium is an aluminium trialkyl and the catalyst also includes an aromatic ester.

10. A process for the production of a hydrocarbon polymer wherein at least one ethylenically unsaturated hydrocarbon monomer is contacted with a transition metal component which is the product of any one of claims 1 to 7 or with an olefin polymerisation catalyst as claimed in claim 8 or claim 9.