GB2090841A - A magnesium-containing Ziegler-Natta catalyst component - Google Patents

Abstract

It has been found that the conventional step of drying support materials to remove residual absorbed water before reaction with other catalyst components can be omitted for components based on diorganomagnesium compounds and transition metal compounds. Satisfactory olefin polymers are still obtained by this simplified and cheaper procedure, with enhanced bulk density for polyethylene in some cases. Organoaluminium compounds and polar additives may be included in the supported component.

Description

SPECIFICATION Catalyst component The present invention relates to a component of an olefin polymerisation catalyst, a process for the production thereof, polymerisation catalysts including the said component and an olefin polymerisation process using such catalysts.

Prior art descriptions of the preparation of so-called supported Ziegler-Natta catalysts, for example UK 916,132, UK 969,766, UK 1,484,254 and UK 1,552,700 often stress that it is essential to use a dry particulate support material, the drying of which is typically effected at a temperature in the range 1 200C to 10000 C, often under reduced pressure, for an extended period of time. We have now found that particulate support materials which have not been subjected to such a drying procedure, hereinafter referred to for convenience as "wet particulate support material", can be used to prepare supported Ziegler-Natta catalyst components. Thus it is possible to eliminate an often expensive heat treatment step in the preparation of supported Ziegler-Natta catalyst components.Furthermore, certain of such catalyst components when used to produce polymers of olefins, or mixtures thereof, surprisingly lead to polymers having a higher bulk density than polymers produced from catalysts based on dry supports.

Accordingly, one aspect of the present invention provides a Ziegler-Natta catalyst component which is the product of treating at least one particulate support material with at least (I) a component I which is, or derivable from, at least one organomagnesium compound of formula R'MgR2, in which R1 and R2, which may be the same or different, are hydrocarbyl groups, and (11) a component II which is at least one transition metal compound of Group IVA, VA or VIA of the Periodic Table, wherein (A) the at least one particulate support material is treated with either component I or component II; and (B) the product from stage A is treated with whichever of component I or II is not used in stage A, characterised in that the at least one particulate support material is at least one wet particulate support material as hereinbefore defined.

All references to the Periodic Table are to the version of the Periodic Table of the Elements printed inside the back cover of "Advanced Inorganic Chemistry" by F A Cotton and G Wilkinson, Third Edition, Interscience Publishers 1976.

In a first preferred embodiment of the present invention the at least one wet particulate support material is treated with (a) a component I which is at least one organomagnesium compound of formula R'MgR2, in which R1 and R2, which may be the same or different, are hydrocarbyl groups; (b) a component Ill which is at least one cleavage agent as hereinafter defined; and (c) a component II; with the proviso that the at least one wet particulate support material is treated with (i) component I, then component Ill, or (ii) component Ill then component (I), or (iii) a mixture, or at least a notional reaction product, of component I and component Ill, prior to being treated with component II. Preferably, the at least one wet particulate support material is treated with component I, then with component Ill and then with component II.

Wherein, in the first preferred embodiment of the present invention, the at least one wet particulate support material is treated with an organomagnesium compound which is at least notionally the product of reacting component I with component Ill, the organomagnesium compound is preferably a compound, or mixture of compounds, which can be represented by the formula RXMgY2-x in which Y is -OR3, -NP32, or --OCOR3, where R3 is a hydrocarbyl group and x has a value from 0.2 up to 1.8, preferably from 0.5 up to 1.5. R' and R3, which may be the same or different, are preferably lower alkyl groups.

By "cleavage agent" we mean a compound which is capable of reacting with the product of Stage A, where component I is used in stage A, to cleave at least a portion of the carbon-magnesium bonds in the product.

In a second preferred embodiment of the invention, component I comprises at least one organomagnesium compound R'MgR2 and at least one aluminium compound of formula R4nAIY3~n, wherein R4, each of which may be the same or different, is a hydrocarbyl or substituted hydrocarbyl group; n is 0, 1, 2, 3 or a fraction less than 3 and Y is a singly charged ligand.Preferably, component I is added to the at least one wet particulate support material before component II, particularly preferably the at least one aluminium compound R4nAIY3~n is added to the at least one wet particulate support material before the at least one organomagnesium R'MgR2 and more particularly preferably a component Ill which is at least one cleavage agent is added to the at least one wet particulate support material after it has been treated with the at least one aluminium compound Rn4AIY3~n and before it is treated with the at least one organomagnesium compound R'MgR2.However, we do not exclude the possibility (a) that the at least one organomagnesium compound R'MgR2 may be added to the at least one wet particulate support material before the at least one aluminium compound RnAIY3~n or that the at least one organomagnesium compound R'MgR2 and the at least one aluminium compound Rn4AIY5 n may be added together, as a mixture, complex or compound, to the at least one wet particulate support material or (b) that a component Ill, where it is used, may be added to the at least one wet particulate support material before or after component I and/or component II have been added to the at least one wet particulate support material.

The at least one wet particulate material used to prepare the catalyst components of the present invention comprises silica, alumina and mixtures thereof. Within the terms silica and alumina we include silica and alumina based materials containing small amounts of other suitable inorganic oxides, such as zinc oxide.

It is preferred that the at least one wet particulate support material comprises alumina since we have found that ethylene co-polymers prepared from catalyst components of the present invention which are based on alumina are more homogeneous than ethylene copolymers prepared from catalyst components of the present invention which are based on silica. The homogeneity of the aforesaid ethylene copolymers can be determined by solvent extraction and/or by dynamic mechanical analysis, e.g. using a du Pont dynamic mechanical analyser.

Typically, the at least one wet particulate support material, where it comprises alumina, contains 20 to 40 per cent by weight of water and, where it comprises silica, contains 5 to 10 per cent by weight of water.

In the at least one organomagnesium compound R'MgR2 used for the preparation of a catalyst component according to the present invention, the hydrocarbyl groups may be alkyl, aryl, cycloalkyl, aralkyl, alkadienyl or alkenyl. The number of carbon atoms in the hydrocarbyl groups is generally between 1 and 30, but this number is not critical. Examples of magnesium compounds particularly suitable for use in the preparation of a catalyst component of the present invention are diethyl magnesium, dipropyl magnesium, diisopropyl magnesium, dibutyl or disobutyl magnesium, butyl octyl magnesium, diamyl magnesium, dihexyl magnesium, diallyl magnesium and didecyl magnesium and didodecyi magnesium, dicycloalkyl magnesium with identical or different cyclo-alkyl groups containing 3 to 12 carbon atoms, preferably 5 or 6 carbon atoms.The magnesium may carry an alkyl and a cycloalkyl group. Diphenylmagnesium is the preferred aromatic compound although, e.g. ditolyl or dixylyl magnesium and magnesium aryls derived from compounds with two or more condensed or noncondensed aromatic nuclei can also be used. Preferably, a dialkyl magnesium is used wherein the alkyl groups are C,--C,, groups, particularly preferably dibutyl magnesium, which may be present as a mixture of dibutyl magnesiums, for example a mixture of di-n-butyl magnesium and di-isobutyl magnesium.

Where the component I comprises at least one aluminium compound of formula R4nAIY3~n and at least one organomagnesium compound, in the at least one aluminium compound of formula Rn4AIY3~n, R4 where present, is preferably alkyl having 1 to 4 carbon atoms, more preferably ethyl or isobutyl, and Y, where present, is preferably a halide, particularly preferably chloride or bromide, and more particularly preferably chloride.

Suitable aluminium compounds of formula Rn4AIY3~n include aluminium chloride, aluminium bromide, monoethyl aluminium dichloride, ethyl aluminium sesqui-chloride and diethyl aluminium chloride.

A component II, which is at least one transistion metal compound, may be any of the transistion metal compounds or mixtures thereof, known to be useful in forming Ziegler-Natta catalysts.

The transition metal of the at least one transistion metal compound is preferably titanium, vanadium, molybdenum, zirconium or chromium, especially titanium. Suitable compounds include halides, halo-oxides, alkoxides, haloalkoxides, and acetyl acetonates, especially chlorides and alkoxides.

The preferred transition metal compound is titanium tetrachloride.

Examples of compounds suitable for use as component Ill include inter alia oxygen, carbon dioxide, aldehydes, ketones, thioketones, esters, thioesters, halogen containing compounds and protic agents. Typically, protic agents are mineral acids, e.g. sulphuric acid, hydrogen halides, carboxylic acids, alcohols, thioalcohols, amines and acetylacetone.

Preferably the component Ill, where it is employed in the preparation of a catalyst component according to the present invention, is (a) an aliphatic alcohol containing from 1 to 6 carbon atoms, for example, methanol, ethanol, n-propanol, isopropanol and the butanols, more preferably n-butanol or (b) a gaseous protic agent, more preferably a hydrogen halide.

Where the component Ill, where it is employed in the preparation of a catalyst component according to the present invention, is a halogen containing compound the halogen containing compound is preferably a halogenating agent and particularly preferably a chlorinating agent. Suitable halogenating agents include hydrogen halides such as hydrogen chloride, silicon halides of the general formula: R5aSiXs4~a, (1); carboxylic acid halides of the general formula R6COX (ill); hydrocarbyl halides of the general formula R7Xb (111); phosphorus pentachloride, thionyl chloride, sulphuryl chloride, phosgene, nitrosyl chloride, halides of mineral acids, chloride, bromine, chlorinated polysiloxanes, hydrocarbyl aluminium halides, aluminium chloride, boron halides and ammonium hexafluorosilicate.In the general formulae (I), (II) and (Ill), R5 and R6, which may be the same or different, are hydrocarbyl groups, preferably alkyl groups containing 1 up to 4 carbon atoms or aryl, alkaryl or aralkyl groups containing 6 up to 1 5 carbon atoms; R7 is a hydrocarbyl residue, preferably an alkyl group containing 1 up to 5 carbon atoms; X is a halide; a is O or an integer from 1 up to 3; and b is an integer from 1 up to 10.

The silicon halides of general formula (I) include silicon tetrachloride, silicon tetrabromide and halosilanes such as trimethyl silicon monochloride, diethyl silicon dichloride and monobutyl silicon trichloride.

The carboxylic acid halides of general formula (II) include acetyl chloride, benzoyl chloride and pmethyl-benzoyl chloride.

The hydrocarbyl halides of general formula (III) include carbon tetrachloride, chloroform, ethyl chloride, ethylene dichloride and 1,1,1 -trichloroethane, Halides of mineral acids include boron trichloride and antimony pentachloride.

Hydrocarbyl aluminium halides include diethyl aluminium chloride and monoethyl aluminium dichloride.

The quantity of the halogenating agent, where one is used in the preparation of the catalyst component of the present invention, is conveniently sufficient to provide at least 0.1, and especially at least 1.0, halogen atom at every reactive site on the at least one wet particulate support material. The treatment can be effected at ambient temperature or at an elevated temperature of up to 100 C. The preferred temperature is dependent on the particular halogenating agent used, for example, using silicon tetrachloride, the temperature is preferably at least 600 C. The treatment is conveniently carried out by adding the halogenating agent to a stirred suspension of the at least one wet particulate support material or of the at least one wet particulate support material treated with the component I.Using a gaseous halogenating agent such as hydrogen chloride, the gas can be passed into the reaction medium until no further absorption is observed to occur. The treatment with the halogenating agent is conveniently effected for a time of at least 0.25 up to 10 hours, preferably from 1 up to 5 hours.

After treatment with the halogenating agent, the solid reaction product is conveniently separated from the reaction medium and washed several times.

It will be appreciated that when the at least one cleavage agent is added last, it may act as a "pacifying agent" i.e. it may temporarily decrease the activity of the catalyst component of the present invention so that it can be added to the monomer feed outside the polymerisation zone and activated when desired.

Magnesium containing Ziegler-Natta catalyst components which are so reactive that they cannot be mixed with an olefin containing stream prior to charging the said stream to a polymerisation zone are known. However, the pacified catalyst components of the present invention are often of sufficiently low polymerisation activity or are substantially completely inactive such that they can be added to the polymerisation zone in the presence of an olefin containing stream.

In the second preferred embodiment of the present invention the molar ratio of the at least one aluminium compound Rn4AIY3~n to the at least one organomagnesium compound R'MgR2 is preferably between 0.5 and 100, particularly preferably between 1.0 and 80 and more particularly preferably between 1.0 and 10.0.

The at least one wet particulate support material, the product of stage A, or the product of stage B may optionally be treated with a component IV which is at least one Lewis Base which is not capable of breaking magnesium-carbon or magnesium-hydrogen bonds, which has been proposed for use in a Ziegler polymerisation catalyst and which affects either the activity of stereo-specificity of such a system. Thus, the Lewis Base compound (other than a cleavage agent) may be an ether, a thioether, a sulphone, a sulphonamide, a fused ring compound containing a heterocyclic sulphur atom, an organosilicon compound such as a silane or siloxane, an amide such as formamide, urea and the substituted derivatives thereof such as tetramethylurea, thiourea, 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 Specification 803198, 809717,880998,896509, 920118,921954,933236, 940125,966025,969074, 971248, 1013363, 1017977, 1049723, 122010,150845,1208815, 1234657,1324173, 1359328, 1383207, 1423658,1423659, and 1423660.

Preferred Lewis Base compounds are esters which may be represented by the general formula: R3COOR9 (lav) wherein R8 is a hydrocarbyl group which may be substituted by one or more halogen atoms and/or hydrocarbyloxy groups; and R9 is a hydrocarbyl group which may be substituted by one or more halogen atoms.

The groups R8 and R9 may be the same or different. The group R8 is conveniently an alkyl or aryl group, for example a methyl, ethyl, phenyl or tolyl group. The group R9 is preferably an alkyl group containing up to 6 carbon atoms, for example an ethyl or a butyl group. It is particularly preferred that R9 is an aryl group and R9 is an alkyl group.

A Lewis Base compound, where one is used in the preparation of a catalyst component of the present invention, may be added to the at least one wet particulate support material treated with the component I and optionally with the at least one cleavage agent. This is conveniently effected by adding the Lewis Base compound to a suspension, in an inert liquid medium such as an inert liquid hydrocarbon or halohydrocarbon, of the at least one wet particulate support material treated with the component I and optionally with the cleavage agent. The quantity of Lewis Base used is conveniently in an amount of up to 1 mole of Lewis Base compound for each gramme atom of metal of component I which is present on the at least one wet particulate support material.Preferred quantities of the Lewis Base are from 0.1 to 0.8 mole for each gramme atom of metal of component I and especially at least 0.5 up to 0.8 mole for each gramme atom of metal of component I.

The addition of the at least one Lewis Base compound to the at least one wet particulate support material may be effected at temperatures of from OOC to 1 000C and is very conveniently carried out at ambient temperature, that is from about 1 50C up to about 300C. After adding the at least one Lewis Base compound to the at least one wet particulate support material the materials are conveniently allowed to remain in contact for 0.1 up to 70 hours, especially 1 up to 20 hours.

After the Lewis Base compound and the at least one wet particulate support material have remained in contact for the desired period of time, the product thus formed is conveniently separated from the reaction medium and washed with an inert liquid.

A further aspect of the present invention provides an olefin polymerisation catalyst which comprises: (a) a catalyst component as hereinbefore defined and (b) an activator which is an organometallic compound of metals of Groups I to IV of the Periodic Table.

Preferably the activator is an organometallic derivative of a metal of Groups IA, IIA, IIB, IIIB or iVB of the Periodic Table, particularly preferably the metal is aluminium and more particularly preferably the activator is a trialkyl aluminium, dihaloalkyl aluminium or halodialkyl aluminium. It will be appreciated that sufficient of the said activator is employed to transform the metal atoms of the transistion metal compound known to be useful in forming Ziegler-Natta catalysts to an active state.

The catalyst component of the present invention may be treated with the aforesaid activator by methods known in the art, for example, they may be reacted totally outside or inside the polymerisation vessel in which the catalyst is to be used or activation may be effected partially outside the polymerisation vessel and completed inside the said polymerisation vessel.

A further aspect of the present invention provides a process for the polymerisation or copolymerisation of an olefinically unsaturated monomer which process comprises contacting, under polymerisation conditions, at least one olefin monomer with a catalyst in accordance with the present invention.

The term "olefinically unsaturated monomer" is intended to include mono-olefins such as ethylene, propylene and 4-methylpentene-1.

The catalysts of the present invention may also be used to initiate the copolymerisation of two or more olefinically unsaturated monomers. For example, ethylene may be copolymerised with a small amount of propylene, butene, hexene or decene, butadiene or styrene.

Polymerisation processes according to the present invention may be carried out by techniques generally used for polymerisation processes of the type using Ziegler catalysts.

The choice of conditions of pressure and temperature will vary with factors such as the nature of the monomer and catalyst and whether liquid, e.g. bulk or diluent, or gas phase polymerisation is used.

For example, when ethylene is polymerised, pressures from sub-atmospheric to several thousand atmospheres may be used. Low pressure (say from 0.1 to 30 atmospheres) and intermediate pressure (say from 30 to 300 atmospheres) polymerisation may be carried out using conventional equipment; but very high pressure polymerisation must be performed using suitable specialised reactors and pumping equipment. However, since, generally speaking, the higher the pressure the higher the activity, the use of such techniques may be justified.If very high pressures are used, it is preferred that conditions are such that the ethylene feed and polyethylene produced are maintained in a single fluid phase, i.e. the pressure should exceed 500 Kg/cm2, preferably 1000 to 3000 Kg/cm2 and the temperature should be greater than 1 250C, say 140--3000C. This type of process is usually operated in a continuous manner.

A wide range of temperatures may be used, but in general low and intermediate pressure ethylene polymerisations are carried out at temperatures in the range 50-1 600 C.

When the process of the present invention is used to polymerise propylene, it is preferred to operate under conditions commonly used for the polymerisation of propylene. However, polymerisation of propylene under other conditions, e.g. high pressure, is not excluded.

It is also within the scope of the present invention to use the catalysts thereof to initiate the copolymerisation of ethylene and propylene together and/or with other olefinically unsaturated monomers.

The polymerisation process of the present invention may be carried out in the liquid or gaseous phase (i.e. in the essential absence of a liquid medium) and preferably in the gaseous phase. Where polymerisation is effected in the liquid phase, and the monomer is not liquid under the polyermisation conditions, the monomer may be dissolved in a suitable solvent. Examples of suitable solvents are aliphatic or aromatic hydrocarbons; for instance butane, pentane, hexane, heptane, octane, decane, benzene, toluene and mixtures thereof.

Polymerisation may be effected either in a batch manner or on a continuous basis, and the catalyst components of the present invention and the activator therefor may be introduced into the polymerisation vessel separately or the catalyst component and activator may be mixed together before being introduced into the polymerisation reactor.

Preferably, however, the polymerisation process of the present invention is effected as a continuous gas phase process such as a fluid bed process. A fluid bed reactor for use in the process of the present invention typically comprises a reaction zone and a so-cailed velocity reduction zone. The reaction zone comprises a bed of growing polymer particles, formed polymer particles and a minor amount of catalyst particles fluidised by the continuous flow of the gaseous monomer, and gaseous diluent to remove heat of polymerisation from the reaction zone. A suitable rate of gas flow may be readily determined by simpie experiment.Make up of the gaseous monomer to the circulating gas stream is at a rate equal to the rate at which particulate polymer product and gas is withdrawn from the reactor and the composition of the gas passing through the reactor is adjusted to maintain an essentially steady state gaseous composition within the reaction zone. The gas leaving the reaction zone is passed to the velocity reduction zone where entrained particles are removed. Finer entrained particles and dust may be removed in a cyclone and/or fine filter. The said gas is compressed in a compressor and passed through a heat exchanger wherein it is stripped of the heat of polymerisation and then returned to the reaction zone.

Chain transfer agents may be used in the polymerisation process according to the present invention, and when ethylene is polymerised their use is normally desirable as the polyethylene produced is of very high molecular weight. Hydrogen may be conveniently used in accordance with usual practice. However, some solvents may act as chain transfer agents.

The process of the present invention is preferably effected under an atmosphere free of oxygen, for example under an atmosphere of an inert gas, e.g. nitrogen, or of the monomer to be polymerised. It is also preferred to effect the process using apparatus and solvents which have been carefully freed from impurities, such as oxygen, water and other substances which would otherwise react with the initiators.

Various aspects of the present invention will now be described with reference to the following Examples which are illustrative of the invention. In the Examples, all operations are effected under an atmosphere of nitrogen unless otherwise indicated. All the glass apparatus was dried in an air oven at 1 200C for at least one hour and purged with nitrogen before use. Hexane and heptane were purified by passage through reduced R3-1 1 copper catalyst (ex. BASF) and 5A molecular sieve and finally by sparging with pure nitrogen immediately before use. Ethylene was purified by passage through R3--1 1 copper catalyst and 5A molecular sieve. Hydrogen was purified by passage through a catalytic deoxygenation unit and 5A molecular sieve.

A. Treatment of alumina A sample of alumina (Ketjen Grade B obtainable from Akzo Chemie of Amsterdam, Holland) was air-classified to 20-120 y and was fluidised with nitrogen for 1 2 hours at room temperature to remove air.

B. Treatment ofalumina A sample of the alumina used in treatment (A) -was evacuated three times to 0.1 mm Hg under nitrogen.

C. Treatment of silica A sample of silica (Davidson 952 grade from W R Grace and Company of Maryland, USA) was subjected to the conditions of Treatment (A).

D. Treatment of silica A slurry of 14.5 gms of a sample of the silica used in treatment (C) in 200 mls of heptane was cooled to -200C and sparged with nitrogen for 1 hour.

Examples 1-5 General Procedure for the Preparation of catalyst Components A slurry of one of the wet particulate support materials recovered from one of the treatments (A)-(C) in 100 mls of heptane, or the slurry recovered from treatment (D), was cooled to -200C and a molar solution of an aluminium compound in heptane was added. The reaction mixture was stirred, the supernatant liquid was decanted and the residual solid was washed four times with 100 ml portions of heptane.

Dry hydrogen chloride gas was passed, for 5 minutes through a slurry of the residual solid in 100 mls of heptane, followed by nitrogen sparging. The supernatant liquid was decanted and the solid was dried under vacuum.

A 0.62 molar solution of dibutyl magnesium in Isopar E was added to a slurry of the solid in 100 mls of heptane and the reaction mixture was stirred for 1 5 minutes. A 1 molar solution of titanium tetrachloride in heptane was added to the reaction mixture and stirred at room temperature and then at 800C for 30 minutes. The reaction mixture was allowed to cool and dry hydrogen chloride gas passed therethrough for 1 minute followed by nitrogen sparging for 1 5 minutes. The catalyst component was filtered off and dried.

Further details of the preparation, including the quantities of reagents used, and the analysis of the catalyst components prepared are given in Table 1.

Examples 6 and 7 A slurry of 7.0 g of the wet particulate support material from treatment (A) in 50 mls of heptane was cooled to -200C and 113 mls of a 0.62 molar solution of dibutyl magnesium in Isopar E was added. The reaction mixture was stirred at ambient temperature for 1 5 minutes and then heated. The supernatant liquid was decanted off and the residual solid was washed four times with heptane.

TABLE 1

Treatment with Treatment with TiCl4 Catalyst Component Aluminium Compound Vol. of dibutyl Vol. of Time at 1gm catalyst component Solution of HCl N2 magnesium TiCl4 ambient contains (milliatoms) Ex. Type of Support Al Compound Reaction treatment sparging solution solution temp.

No. (wt. in gms) (Vol in mis) Conditions (mins) (mins) (mis) (mis) (mins) Tl Mg Al Cl -20 C/30 mins 1 A iBu3Al then 5 30 100 12.5 15 0.77 1.46 a 7.09 (13.6) (136) 60 C/1 hour -20 C/30 mins 2 B iBu3Al then 5 30 43.4 15 15 1.01 1.82 a 8.02 (11.1) (109) 60 C/1 hour 1.5 hrs up to 3 D Et2AlCl ambient 2 30 46.7 14.5 15 0.51 1.35 2.29 6.77 (14.5) (100) temperature 20 C/1 hour 4 B Et2AlCl then 5 15 36.8 11-4 90 0.79 1.67 a 7.90 (7.5) (45) 90 C/2 hour 20 C/1 hour 5 D iBu3Al then 5 15 48 15 60 0.38 1.10 2.28 3.48 (14.5) (80) 65 C/1 hour a: not determined TABLE 2

Treatment Catalyst Slurry of Support Treatment with MgBu2 Treatment with BuOH with TiCl4 Component 1 gm catalyst component Volume of contained Type of Volume of Volume of Volume of Heptane in Volume Time at (milliatoms) Example Support Heptane MgBu2 soln Time BuOH Slurry Time of TiCl4 80 C No. (wt in gms) (mis) (mis) Temp (hrs) (mis) (mis) (mins) (mis) (hrs) Ti Mg Cl 6 A 50 113.0 Reflux 3 2 50 15 50 1 0.73 5.48 4.47 (7) 7 C 100 132.8 60 C 2 3 80 60 80 2 1.33 1.71 6.35 (13.7) CT1 a 100 135.5 20 C 15 6.25 100 5 80 2 0.96 2.99 5.86 (19.2) CT2 b 100 75.5 20 C 15 4.6 100 10 80 2 0.87 1.41 5.10 (15.6) CT: Comparative Experiment.

a: Ketjen Grade B alumina azeotroped at 180 C in hydrocarbon solvent having a boling range of about 170 C - 190 C.

b: Ketjen Grade B alumina dried at 500 C for 2 hours.

N-butanol was added to a slurry of the residual solid in heptane. The reaction mixture was stirred for 1 5 minutes, filtered, washed twice with 50 mls portions of heptane and the solid was dried under vacuum.

Titanium tetrachloride was added to the solid and the mixture was heated at 800 C. The excess titanium tetrachloride was removed by filtration and the residual solid was washed with heptane at 700C until chlorine could not be detected in the washings. The solid was then dried under vacuum to afford a catalyst component according to the present invention. Further details of the catalyst components and of the preparation thereof are given in Table 2.

In comparative experiments dried alumina was used as the particulate support material. Details of the comparative experiments are given in Table 2.

Examples 8-20 General Polymerisation Procedure A one US gallon stainless steel pressure vessel was prepared by heating it to 1 000C and evacuating with an efficient vacuum pump. The vessel was then cooled to 600C and 2 litres of purified hexane added. The vessel was then sparged at reaction pressure with about 200 litres of pure ethylene over a period of 30 minutes to remove any residual moisture and oxygen, after which it was vented. 6 mls of a molar solution of aluminium trioctyl in heptane as activator and then the catalyst component as a slurry was injected against a stream of ethylene.The vessel was then sealed and pressurised with hydrogen to a pressure of 1.76 kg/cm2 absolute (except for Example 1 7 where the hydrogen pressure was 3.16 kg/cm2 absolute) and then with ethylene to a reaction pressure of 11.57 kg/cm-2 absolute.

Where an ethylene/butent-1 copolymer was prepared 200 mls of butene-1 was added from a Klinger gauge during pressurisation. When full reaction pressure was reached the vessel was stirred at 1000 rpm and polymerisation commenced. Reaction was allowed to continue for a desired period of time at 800 C, during which time ethylene was added as required to maintain the reaction pressure. Afterwards, the reactor was vented and cooled.

Where the product was a copolymer the reaction slurry was removed from the autoclave and to this was added 1 litre of deionised water and 0.02 wt/vol of sodium di(2-ethylhexyl) sulphosuccinate (Aerosol OT) calculated on polymer slurry, i.e. diluent, as a wetting agent. Steam at 1 000C was then passed into the stirred vessel at about 25 g per minute and the mixture distilled at a temperature of about 600 C, distillation being continued until no more organic material separated from the distillate.

The polymer product, which was granular in form, was then filtered from the aqueous slurry remaining in the distillation vessel, washed with water and dried under vacuum at approximately 600 C.

Where an ethylene homopolymer was prepared, the product was recovered by direct filtration of the reaction slurry at room temperature followed by drying at 600C.

Further details of the polymerisation procedure including the type of activator and amount of catalyst component used, and of the polymeric products are set out in Table 3 and 4.

The methyl content of the polymeric products, i.e. methyl groups which are at ends of molecules and those which are at ends of side branches, are measured using a mathematical comparison, by computer, of the absorbance curve from 1310--1430 cm-' with two standard polyethylenes of known methyl count.

Melt flow index (MFI) was determined as described in ASTM D1238.

Flow ratio (FR) was determined as in ASTM D1238--70, Procedure A, being the ratio of the MFI measured using a 21.6 kg weight with that measured using a 2.1 6 kg weight both measurements being carried out at 1 900C.

Density was measured as described in ASTM D1928--70, Procedure A, using a density gradient column at 23"C and includes a correction for the presence of catalyst residues.

Powder bulk density was determined by pouring the powder via a 0.95 cms diameter funnel into a 100 ml graduated cylinder to the 100 ml line without shaking them.

TABLE 3

Reaction Product Catalyst Component Conditions Powder Hydrogen Melt Bulk Ex. Prepared Amount Pressure Time Yield Me content/ flow Flow Density Density No. in Example (m.Atoms Ti) (Kg/cmȃ) (hrs) Type (g) 1000 O atoms Index Ratio (g/c.c.) (g/cc) 8 1 0.05 1.76 2 Copolymer 215 14 1.12 38.3 0.9318 a 9 1 0.05 1.76 2 Homopolymer 194 b 0.045 58 a 304 10 2 0.05 1.76 2 Copolymer 291 22.5 4.9 35 0.9272 a 11 6 0.1 1.76 2 Copolymer 316 20 5.9 36 0.973 372 12 3 0.02 1.76 4 Homopolymer 437 b 0.12 45 a 291 13 3 0.05 1.76 2 Copolymer 267 29 10.6 a a a 14 4 0.05 1.76 2 Copolymer 301 15 1.6 40 0.9324 a 15 5 0.05 1.76 2 Copolymer 326 29 12.6 a 0.9199 a a: not determined b: not applicable TABLE 4

Product Catalyst Component Powder Reaction Conversion Me content / Melt Bulk Example Prepared in Amount Time Yield (gms polymer/ 1000 C flow Flow Density Density Number Example (m. atoms Ti) (hrs) Type (g) gm catalyst) atoms Index Ratio (g/cc) (g/cc) 16 6 .02 4 Homopolymer 102 3,723 b 0.05 51 a 427 17 6 .04 1 Copolymer 37 67,5 10 1.45 88 a a 18 7 .05 2 Copolymer 249 6,622 22 2.06 48 .9268 a 19 7 .02 4 Homopolymer 27.4 18,267 b 0.11 58 a a 20 6 .04 4 Homopolymer 143 2,610 b 0.56 41 a 412 CT3 CT1 .02 2 Homopolymer 107 6,000 b 0.32 39 .9459 442 CT4 CT2 .04 2 Homopolymer 241 4,720 b 0.61 40 .9324 420 a: Not determined b: Not applicable CT: Comparative experiment Powder bulk density (g/l) = (Wt of cylinder with powder - Wt of empty cylinder) x 10.

In comparative experiments, catalyst components derived from dried alumina were used. Details of the polymerisation procedures and of the polymeric products thereof are given in Table 4.

From Table 4 it can be seen that a catalyst component of the present invention has the advantage that when used for the production of polyethylene it can give, at low conversion, polyethylene of bulk density similar to that of a polyethylene produced, at high conversion, by using a catalyst component based on a dried support.

Claims (13)

1. A Ziegler-Natta catalyst component which is the product of treating at least one particulate support material with at least (I) a component I which is at least one organomagnesium compound of formula R'MgR2, in which R' and R2, which may be the same or different, are hydrocarbyl groups, (II) a component II which is at least one transition metal compound of Group IVA, VA or VIA of the Periodic Table, wherein (A) the at least one particulate support material is treated with either component I or component II; and (B) the product from stage A is treated with whichever of component I or II is not used in stage A, characterised in that the at least on particulate support material is at least one wet particulate support material as hereinbefore defined.

2. A Ziegler-Natta catalyst component as claimed in claim 1 wherein the at least one wet particulate support material is treated with a component Ill which is at least one cleavage agent as hereinbefore defined with the proviso that the at least one wet particulate support material is treated with (i) component I, then component Ill, or (ii) component Ill then component I or (iii) a mixture, or at least a notional reaction product, of component I and component Ill, prior to being treated with component II.

3. A Ziegler-Natta catalyst component as claimed in claim 2 wherein the at least one wet particulate support material is treated with component I, then with component Ill and then with component II.

4. A Ziegler-Natta catalyst component as claimed in claim 2 wherein the at least one wet particulate support material is treated with an organomagnesium compound which is at least notionally the product of reacting component I with component Ill which organomagnesium compound is a compound or mixture of compounds which can be represented by the formula RxMgY2~x in which Y is -OR3, -NP32, or --OCOR3, where R3 is a hydrocarbyl group and x has a value from 0M2 up to 1.8.

5. A Ziegler-Natta catalyst component as claimed in claim 1 wherein component I comprises at least one organomagnesium compound R'MgR2 and at least one aluminium compound of formula R4nAiY3~n, wherein R4, each of which may be the same or different, is a hydrocarbyl or substituted hydrocarbyl group; n is 0, 1, 2, 3 or a fraction less than 3 and Y is a singly charged ligand.

6. A Ziegler-Natta catalyst component as claimed in claim 5 wherein the at least one wet particulate support material is treated with component I and then component II.

7. AZiegler-Natta catalyst component as claimed in claim 6 wherein the at least one aluminium compound R4nAIY3~n is added to the at least one wet particulate support material before the at least one organomagnesium compound R'MgR2.

8. A Ziegler-Natta catalyst component as claimed in claim 7 wherein a component Ill as defined in claim 2 is added to the at least one wet particulate support material after it has been treated with the at least one aluminium compound R4AIY3~n and before it is treated with the at least one organomagnesium compound R'MgR2.

9. A Ziegler-Natta catalyst component as claimed in any one of the preceding claims wherein the at least one wet particulate support material comprises alumina.

10. A Ziegler-Natta catalyst component as claimed in any one of the preceding claims wherein component II comprises a titanium halide.

11. A Ziegler-Natta catalyst component as claimed in any one of claims 2 to 5 and 8 wherein component Ill comprises an aliphatic alcohol containing 1 to 6 carbon atoms or a gaseous protic agent.

12. A Ziegler-Natta catalyst comprising a Ziegler-Natta catalyst component as claimed in any one of claims 1 to 11 and an activator for a Ziegler-Natta catalyst component which activator is an organometallic compound of a metal of Groups I to iV of the Periodic Table.

13. A process for the polymel-isation or copolymerisation of an olefinically unsaturated monomer which process comprises contacting, under polymerisation conditions, at least one olefin monomer with a catalyst as claimed in claim 12.