IE45018B1 - Catalyst, its production and use in polymerization of olefins - Google Patents

Abstract

For the preparation of the trichlorides of titanium and vanadium, a metal is vaporised in vacuo and the vapour thus obtained is reacted at low temperature with MCl4, M being Ti or V. The vaporisation of the metal takes place in a vacuum of between 10<-1> and 10<-6> mm Hg, and the reaction of the metallic vapours and MCl4 takes place at temperatures of between -80 and +20 DEG C in the presence of an inert diluent selected from saturated or unsaturated aliphatic hydrocarbons or from halogenated hydrocarbons. The metal to be vaporised is preferably selected from the group comprising Al, Mg, Cr, Mn, Fe, V and Ti. The trichlorides thus obtained and an organometallic aluminium compound are used in catalytic compositions for the polymerisation of alpha-olefins in high yield.

Description

This invention relates to co-catalysts for use in the polymerization of an α-olefin with itself or with a monomer copolymerizable therewith, to catalytic systems including such co-catalysts, and to the use of such catalytic systems in the polymerization of an α-olefin with itself or with a monomer copolymerizable therewith.

According to the invention, there is provided a process for preparing a co-catalyst for use in the polymerization of an a-olefin with itself or with a monomer copolymerizable therewith, which process comprises vaporising a metal and reacting the resulting vapour with a compound of titanium or of vanadium in the presence of a halogen donor, the reaction being carried out in an inert carbonaceous diluent.

It will be noted that the process of the invention is carried l out in the presence of a halogen donor. However, the use of a separate donor is not necessary when the compound of titanium or vanadium is itself a halogen donor.

The invention also provides a catalytic system for use in the polymerization of an α-olefin with itself or with a monomer copolymerizable therewith, the system comprising first and second co-catalysts, the first co-catalyst being a co-catalyst of the invention and the second co-catalyst being an organo-aluminium compound.

The invention .further provides a process for the polymerization of an α-olefin with itself or with a monomer copolymerizable therewith, wherein the polymerization is carried out in the presence of a catalytic system of the invention.

The organo-sluminium compound preferably has the general formula AIRnX3_n, wherein R is an alkyl or aryl group or a hydrogen atom, X is a halogen atom, and n_ is 1, 2 or 3. The metal vapour, preferably obtained by heating the metal concerned in a high vacuum, is preferably selected from Mg, Al, Ti, V, Cr, Mn, Fe and their alloys. The compounds of Ti or V may be, for example, inorganic or organic salts, complexes or compounds thereof, in which the metal has a valency higher than 3. The halogen donor can be organic or inorganic, and is capable of yielding halogen (mobile halogen) to the metal to be vaporised or to the titanium or vanadium compound under the working conditions which are used.

The reaction is carried out in an inert carbonaceous diluent, for example an aliphatic, aromatic or nixed compound, which is liquid under the working conditions.

The metal is vaporised, preferably in vacuo, by an appropriate heating system (e.g. by electric resistors, by electron beams, by induction, by high frequencies, by laser beams, by electric sparks or by a voltaic arc). The vapours emerging from the metal surface are quenched in the inert diluent, which contains the titanium or vanadium compound and the halogen donor.

The inert diluent may be cooled to a temperature which is low enough to limit its evaporation so as consequently to permit the maintenance of the degree of vacuum required for the vaporisation of the metal at the temperature attained by the heating system.

The catalyst system is capable of polymerizing and copolymerizing, with very good yields, ethylene and higher ο-olefins to form highdensity polyethylene and isotactic polypropylene, respectively, and is likewise capable of polymerizing butadiene to form 1,43 4S013 transpolybutadiene and isoprene to form 1,4-cispolyisoprene.

As regards ethylene, a few of the catalyst systems in question are capable of displaying an exceptional activity in the polymerization thereof. More particularly, when the co-catalyst is prepared from magnesium vapours and a titanium compound in the presence of a halogen donor, it has been surprisingly found that extremely high yields can be obtained when the atomic ratio of Mg to Ti is equal to or higher than 4 and when the atomic ratio of X to Mg is equal to or higher than 2, wherein X is the mobile halogen. These co-catalysts afford substantial advantages over known catalysts with respect to the yield of polymer.

For example, the activity (in terms of kilograms of polymer per gram of titanium produced in one hour in an atmosphere of ethylene under the conditions set forth in the Examples below) can be extremely high, i.e. of the order of magnitude of 230 kilograms. The co-catalyst can be prepared from raw materials which are particularly simple and which can be standardized, and thus'gives rise to co-catalysts having an activity which is both homogeneous and reproducible. The preparation of the co-catalyst is both simple and quick. The co-catalyst can be employed as prepared, in conjunction with the other co-catalyst, by a slurry polymerization, without separation, filtration or elution. More particularly, all of the transition metal reacted is usually converted to an active co-catalyst. The co-catalyst can be employed, after having been dispersed on an inert support (which can even be the polyolefin as such), in the polymerization of ethylene in the gaseous state, without any hydrocarbonaceous dispersant being present. Adjustment of the molecular weight of the polymer with hydrogen over a wide range, e.g. a range such that the Melt Flow Index (hereinafter abbreviated to MFI) of the polymer is from 0,1 to 15, does not normally involve loss of yield of polymer with respect to the transition metal. 3 01 S In an embodiment of the invention, the metal vapour is condensed in MCI4 (M being either Ti or V), diluted in an inert carbonaceous diluent, the latter being kept at a low temperature. The principle advantage of such a procedure is that it can be applied generally, that is to say that the vapour of any metal can be used, irrespective of whether or not it is a transition metal. In addition, there is the advantage that there is obtained products which have had a controlled thermal history and thus have differentiated physical properties, and consequently different catalytic activities, many metals being controllably and simultaneously co-vaporisable. The products thus obtained can be used as catalysts for the polymerization and copolymerization of olefins, using organo-aluminium compounds as co-catalysts.

According to an embodiment of the invention,the trichlorides of titanium or of vanadium are obtained by reacting MC'I^ with a vaporised metal, preferably selected from Al, Mg. Cr, Kn, Fe, V and Ti. The vaporisation is generally carried out in a very high vacuum, preferably -3 -fi from 10 Torr to 10 0 Torr, at a temperature which depends upon the metal which is used, and is usually from 800°C to 2500°C, as disclosed by P.L. Timms, Angew, Chem., 14, 273 (1975). The metal vapour is generally reacted with MCl^ at a temperature in the range of from -80°C to +20°C, preferably from -60°C to -20°C. The reaction with MC14 is carried out in an inert carbonaceous diluent such as an aliphatic or aromatic, saturated or unsaturated hydrocarbon or a halogenated hydrocarbon, e.g. chlorohexane or f’uorobenzene. The choice of solvent or solvent mixture depends upon the conditions of use (e.g. temperature of solidification and vaporisation under the pressure used). 43018 It has been found, moreover,, that if in the above-mentioned preparation, a high ratio of Mg to Ti is adopted and the reaction is carried out in the presence of a halogen donor, it is possible to obtain a co-catalyst which, together with an organo-aluminium compound, provides outstandingly good results in the polymerization of a-olefins, particularly ethylene, as such or in admixture with one or more of its higher homologues. More particularly, such a co-catalyst is obtained by vaporising magnesium or an alloy thereof, then condensing it in an, inert carbonaceous diluent which contains the titanium compound and the halogen donor.

The vaporisation of the magnesium is preferably carried out in vacuo, e.g. at a pressure of from TO^ Torr to 104 Torr, and at a temperature dependent upon the pressure used, e.g. from 500°C to 1200°C.

The metallic vapours may be condensed in a solution, kept stirred, of the titanium compound and the halogen donor in the inert diluent, at a temperature higher than the freezing point and lower than the boiling point of the solution.

As outlined above, preferred co-catalysts of the invention have a high ratio of Mg to Ti, especially a ratio equal to or higher than 4. The use is necessary of a halogen donor selected from organic and inorganic halogenated compounds. The halogen donor may be employed in an excess amount with respect to the magnesium. It is preferred that the ratio of the halogen donor to the magnesium be equal to or higher than 2. The condensation of the magnesium vapour is carried out in an inert carbonaceous diluent, e.g. an aliphatic or aromatic hydrocarbon. * 3 01 a The titanium compound is preferably a compound of tetravalent titanium and preferably soluble in the selected diluent. The halogen donor may be an organic or inorganic halide, alkyl arid aryl halides being preferred.

At the end of the reaction, a very fine slurry is obtained, which can be used as such in the polymerization. Thus, the polymerization • reaction may be carried out in the presence of a catalyst system comprising the suspension in the form in which it is obtained and an organoaiuminium compound, in a hydrocarbonaeeous solvent, which can be the same as that employed in the above described preparation.

The temperature of polymerization is generally from 20°C to 2Q0°C, preferably from 50°C to 200¾, and ths pressure is generally from 1 to 20 atmospheres. As an alternative, when it is desired to carry out the polymerization in the gaseous state, the co-catalysts can be dispersed in a low-boiling solvent, so that the latter can easily be removed. The co-catalysts can also be dispersed on an inert solid support, e.g. the polymer itself. The polymerization in the gaseous phase is generally carried out at a temperature of from room temperature to a temperature below the melting point of the polymer being produced. In the particular case of the polymerization of ethylene, the temperature range which is preferred is from 40¾ to SO°C. The pressure is preferably from 1 to 60 atmospheres. Hydrogen can be employed as a regulator of the molecular weight.

The invention will now be illustrated by the following Examples, &G0l3 EXAMPLE 1 This Example describes the preparation of 3TTC13.A1C13.

There was used a rotary flask at the centre of which was arranged a spirally wound tungsten filament connected to a source of electrical power. Under the flask, a cooling bath was positioned. In the top portion of the apparatus there were a nitrogen inlet and an outlet for reducing the pressure in the flask.

Within the spirally wound tungsten filament there were placed 150 mg of pure aluminium in flake form. The flask was charged under nitrogen with 250 ml of anhydrous decane containing TiCl^ in an amount of 30% of the amount of decane. The rotary flask was cooled by the bath, which was at -40°C, and then the pressure was reduced by a diffusion pump to 10“^ Torr, Once these conditions had been attained, the filament was heated until the metal vaporised. The vaporised metal immediately reacted with the TiCl^, giving a very fine dark-brown precipitate. On completion of the vaporisation, the flask was brought to ambient pressure and temperature by feeding in nitrogen. The suspension was then kept at 150°C for three hours. Upon filtration and drying, a violet product was obtained. Its analysis was as Follows: ATCl3.3TiCl3 Ti: A155 Cl% Calcd. 24.12 4.52 71.36 Found 24.01 4.90 69.80 EXAMPLE 2 The same apparatus and procedure of Example 1 were used. The reactants used were 190 mg of pure metallic magnesium in wire form and 250 ml of octane containing 2% of TiCl^. Upon cooling to -60°C 430lQ and attaining a vacuum of 10“4 Torr, the vaporisation of the metal was started. It took five minutes. A fine brown-violet precipitate formed. The flask was restored to ambient pressure and temperature. The suspension was kept at 125°C for 4 hours, whereafter the suspension was filtered and the violet precipitate was washed with n-heptane until the TiCl4 had been completely removed. The solid product was dried in vacuo. The. dried product (2 g) was analysed: MgCl2.TiCl3 Calcd. Ti% 23.76 5.94 Cl% 70.28 Pound 22.97 5.8 57.1 The two samples, i.e. the untreated one and the treated one, have a gamma structure, according to '/-ray analysis.

EXAMPLE 3 The same apparatus and the same procedure as in Example 2 were used, except that the n-octane contained 142 of TiCl4.

A brown-violet product was obtained. The product was filtered, washed with η-heptane until the TiCla was completely removed, reslurried in n-heptaoe and analysed. The analysis gave the empirical formula H9Til:84C18.1.

EXAMPLE 4 The same apparatus and procedure as in Example 1 was used. The reactants were 0.240 g of metallic magnesium in wire form and 300 ml of n-octane containing 0.07% of TiCl4 and 12% of n-chlorohexane. After cooling to -60°C, a vacuum of 104 Torr was applied, and the magnesium was vaporised in 7 minutes. A solid, pale- brown product formed. The 43018 product was filtered off, washed with n-heptane and kept at 100°C in n-heptane for two hours. Analysis gave the empirical formula Mg3.1TllC17.8· EXAMPLE 5 The same apparatus and procedure as described in Example 1 v/ere used. The reactants used were 0.180 g of metallic manganese in flake form and 250 ml of octane containing 2% of TiC1A. Upon cooling to -60°C, a vacuum of IO’4 Torr was applied. The vaporisation of the metal was started. This was completed in 3 minutes. A brown-violet precipitate was formed. The flask was brought back to ambient temperature and pressure. The suspension was filtered, and the product was washed with n-hexane until the TiCJ had been completely removed, dried in vacuo, and analysed. The results of the analysis are: 2TiCT3.MnCl2 Tig Cig Mng Calcd. 22,0 65.30 12.63 Found 22.0 63.4 14.4 EXAMPLE 6 The same apparatus and procedure as disclosed in Example 1 were used. The reactants were 0.25 g of metallic iron shavings and 250 ml of anhydrous n-octane containing 5% of TiCJ. Upon cooling to -50°C, -3 a vacuum of 10 Torr v/as applied and the vaporisation of the metal v/as started. This took 5 minutes. A solid red-brown product was formed. This product was collected on a filter, washed v/ith anhydrous hexane and dried under vacuum. There were obtained 1.87 g of a product which had the following analysis: FeCl2.2TiCl3 TO Fe% CU Calcd. 21.99 12.81 65.19 Found 21.73 12.70 66.90 EXAMPLE Ί The same apparatus and procedure as disclosed in Example 1 were used. The reactants were 0.125 g of magnesium wire and 250 ml of n-octane containing 3 ml of VCl^. Upon cooling to -60°C5 a vacuum of 10 Torr was applied and vaporisation of the metal was started. This took 5 minutes. A solid dark-brown product was formed. This product was washed with n-heptane to remove VC14 and rsslurried in n-heptane. Analysis gave the empirical formula tigV., ,C13 3θ.

EXAMPLE S The same apparatus and procedure as disclosed in Example 1 were used. The reactants were 1 g of meta!lie chromium in lump form and 250 ml of n-heptane containing ID ml of TiCl^. Upcn cooling to -80°C, a vacuum of about IO'4 Torr was applied and vaporisation of the metal was started. This took 20 minutes to be completed. A solid greenish product was formed. This product was filtered off and washed with heptane to remove TiCl^, and reslurried in heptane. Analysis gave: CrCl3.3TiCl3 TO Crf. CU Calcd. 23.19 8.37 68.44 Found 23.40 8.20 67.60 . . . - ?./' \ r -..

. ' A 5-litre autoclave was charged with 2 litres of anhydrous n-heptane containing the co-catalyst prepared according to Example 3 in a concentration of 0.03 miHigramatoms of titanium and --. 4 miHigramatoms of Al(iso-Bu)g. The mixture was brought to 85°C.

Then, hydrogen and'ethylene were introduced, each to a partial pressure of 5 kg/cm2. .- Polymerization was carried out for four hours while maintaining the total pressure constant by the addition of ethylene. On completion of the polymerization, the slurry was centrifuged, and the polymer was dried in vacuo at 50°C for four hours and then weighed.

There was obtained a white-polymer in an amount of 400 g, equivalent to a yield of 6,440 g of polymer per gram of titanium per hour and per atmosphere of ethylene. The polymer had an MFI of 0.60.

EXAMPLE 10 The procedure was the same as in Example 9, using the co-catalyst described in Example 1 in a concentration of 0.06 miHigramatoms per _ litre of titanium and, as the other co-catalyst, Al(iso-Bu)g in a concentration of 4 nnHigramatcms per litre. Hydrogen and ethylene were o introduced, each to a partial pressure of 5 kg/cm . Polymerization . was carried out for 4 hours under a pressure kept constant by introducing ethylene; There were obtained 120 g of a white polymer, which corresponds to a specific yield of 1,030 g of polymer per gram of titanium per hour and per atmosphere of ethylene. The polymer had an MFIg ig of I.E and an MFIgj g/MFig ratio of 49.4. 45033 EXAMPLE 11 A 2-litre autoclave was charged with 1 litre of anhydrous and deaerated n-hexane containing 20.8 mg of a co-catalyst according to Example 6 (equivalent to 0.0941 milligramatoms of titanium) and 4 milligramatoms of Al(iso-Eu)3. Hydrogen and ethylene were introduced, each to a partial pressure of 20 kg/cm2. The temperature was raised to S5°C and the pressure was maintained constant by the continuous introduction of ethylene. ' After 2 hours of polymerization, the reactants were cooled, the autoclave was vented and the polymer was centrifuged, dried under vacuum at 50°C and weighed. There were obtained 320 g of a polymer having an MEI, of 0.12 and an MFIgi g/MFI? ratio of 44.7. The yield was 1,750 g per gram of titanium per hour and per atmosphere of ethylene.

EXAMPLE 12 Tne procedure was the same as in Example 9, using the co-catalyst described in Example 5 in a concentration of 0.10 milligramatoms of titanium per litre. As the other co-catalyst there was used Al(iso-Bu)3 in a concentration of 4 milligramatoms per litre.

Hydrogen and ethylene were introduced into the autoclave, each to a partial pressure of 5 kg/cnfv Polymerization was carried out for 3 hours. There were obtained 390 g of a polymer having an MFIg of 0.35 and an MFI2^ g/MFIg ratio of 35. The yield was 2,700 g per gram of titanium per hour and per atmosphere of ethylene.

EXAMPLE 13 The procedure was the same as in Example 9, using the co-catalyst described in Example 8 in a concentration of 0.026 milligramatoms of titanium per litre and 2 milligramatoms of Al(iso-Bu)3 per litre. 45»i8 .Hydrogen and ethylene were introduced into the autoclave, the former to a partial pressure of 5 kg/cm and the Tatter to a partial pressure of 5.5 kg/cm2. The temperature was raised to 85°C and the pressure maintained constant by the continuous introduction of ethylene. After two hours of polymerization, the reactants were cooled, the autoclave was vented and the polymer was filtered off, dried in vacuo at 50°C and weighed. ' There were obtained 108 g of a polymer having an .

MFI of Ο.Π. The yield was 3,900 g of polymer per gram of titanium per hour and par atmosphere of ethylene.

Table ! tabulates the specific activities as obtained in the polymerization of ethylene using the co-catalysts prepared according to Examples 2, 3, 5, 6 and 8 and the polymerization procedures according to Examples 10, 9, 12, 11 and 13.

TABLE 1 .-- Catalyst Cata- lyst Polymer- ization Specific activity (g polymer/g of Ti/ hr/atm. of ethylene) mfi2J (g/io min) MFI, MFI, 3TiCl3.AlCl3 1 10 1,030 0.62 ; 49 2TiCl3.MgCl2 3 9 6,440 0.60 36 2TiCl3.MnCl2 5 12 2,700 0.35 35 2TiCl3.FeCl2 6 n 1,750 0.12 35 3TiCl3.CrCl3 8 13 3,900 o.n 47 EXAMPLE 14 A 100 ml two-necked flask which had been purged with an inert gas was charged in an inert atmosphere with 30 ml of anhydrous n-hexane and then with the co-catalyst according to Example 3 in an amount of 0.1 nrillimol of titanium, 0.1 millimol of Al(iso-JHgJj and subsequently with 7 g of anhydrous isoprene twice distilled over LiH, The mixture contained in the flask was stirred for two hours at a temperature of 20°C ana then poured into 300 ml of methyl alcohol containing 1% of an antioxidant. The coagulated polymer was dried under vacuum at room temperature overnight. The yield of solia polymer was 6.3 g, corresponding io 90% of the monomer, NMR analysis showed the predominant pressure of a structure of the 1,4-cis type.

EXAMPLE 15 A 2G0 ml lemonade bottle, whish had previously been purged with an inert gas, was charged in an inert atmosphere with 90 ml of anhydrous n-hexane and then with the co-catalyst according to Example 7 in an amount of 0.5 millimol of V and 1 milltol of A'lEJ. The bottle was stoppered with a neoprene plug and with a perforated crown cap so that a hypodermic needle can be introduced. At this stage, by means of a hypodermic needle directly welded to a metal bottle which contained butadiene, there were introduced 14 g of butadiene in liquid form. The lemonade bottle was placed in a rotary bath thermostatically maintained at a temperature of 20°C for 1£ hours. On completion, the lemonade bottle was opened and its contents were discharged into 500 ml of methanol containing 1 of ionol. The coagulated polymer was dried in vacuo for 16 hours. The yield of solid polymer was 1.8 g, corresponding to 13% of the monomer. IR examination showed a structure which was essentially 1,4-trans.

EXAMPLE 16 -A 2-1 lire autoclave was charged with one litre of anhydrous and deaerated n-hexane containing 340 rag of the co-catalyst according to Example 8, corresponding to 1.66 mi Hi grama toms of titanium, and 7 milligramatcms of AlEt3, per litre. Propylene was introduced to a pressure of 8 kg/cm^. The temperature was raised to 65°C and the pressure was;kept constant by feeding in propylene, over a period of 6 hours. Upon cooling the autoclave, the polymer was collected on a filter and dried in vacuo at 50°C. There were obtained 135 g of a polymer having a crystallinity (RX) of 42% and a residue of 85% after extraction with hexane. 430 2 8 EXAMPLE 17 Preparation of the catalyst The same apparatus as described in Example '1 was used. The tungsten spiral was charged with 800 mg of magnesium needles. The 500 ml flask was charged under nitrogen with 130 ml of anhydrous and deaerated n-heptane. 20 ml of 1-chlorohexane (145 millimol) and 0.15 ml of TiCl4 (1.35 millimol). The flask was cooled to -70°C, a 10‘3 Torr vacuum was applied, and the spiral was heated so as to vaporise the metal. A very fine grey-brown precipitate was formed. On completion of the vaporisation (about 15 minutes) nitrogen was introduced into the apparatus and the flask was brought back to ambient temperature whilst stirring was continued. Analysis of the slurry showed that it had a Mg:Ti molar ratio of 24 and a Cl:Ti molar ratio of 45.

Polymerization A 5-litre autoclave having an anchor-stirrer was charged with 2 litres of anhydrous and deaerated n-heptane, 4 miliimols of Al(iso-Bu)3 and a quantity of the above co-catalyst corresponding to 0.01 milligramatoms of elemental titanium. The temperature was raised to 85°C and hydrogen to a partial pressure of 5 kg/cm2 and ethylene to a partial pressure of 3.5 kg/cm2 were introduced. Ethylene was continuously fed in so as to keep the total pressure constant over a period of one hour. There were obtained 350 g of polyethylene having an MFI of 9.8 g/ΊΟ min and a density of 0.9690 g/cm . The specific activity was 200,000 g of polymer per gram of titanium per hour and per atmosphere of ethylene. : example 18 ; The method of Example 17 was repeated, using bromohexane instead of chlorohexane. A slurry was obtained, having a Mg:fi ratio of 16.5 and a (Br + GT): Ti ratio of 33.

, In the polymerization of ethylene, under the conditions of - Example 17, there were obtained 165 g of a polymer having an MEI of 4.18 g/10 min, corresponding to a specific activity of 98,000 g per gram of titanium per hour and per atmosphere of ethylene.

EXAMPLE 19 Using the. procedure of Example 17 and the same reactants, there were prepared several co-catalysts having different Mg to Ti ratios, the activities of which in the polymerization of ethylene, carried out under the conditions of Example 17, are tabulated in Table 2.

- - TABLE 2 Mg Ti Specific activity' (grams of polymer per gram of titanium per hour and per atmosphere of ethylene) MFI (g/min) Apparent density (specific gravity) (g/em3) MFI21 «Tl 5,0 47,000 ( 16.0 - 0.25 22 9.0 57,000 6.8 0.23 34 13.4 90,000 11.4 , 0.22 35 16.5 95,000 11.3 0.24 28 22.7 125,000 10.3 0.22 36 25.0 200,000 9.8 0.24 23 35.0 280,000 10.1 0.20 35 EXAMPLE 20 «5013 The procedure of Example 17 was repeated, using 1,100 mg (46 milligramatoms) of magnesium, 0.2 ml (0.68 millimol) of TiClgiO-iso-CjHyJg and 20 ml (142 millimol) of CgH^-Br in 200 ml n-octane.

Analysis of the suspension obtained gave the following results: Mg:Ti ratio = 48; (Br + Cl) : Ti ratio = 83.5 In the polymerization of ethylene under the conditions of Example 17, there were obtained 265 g of a polymer having an MFI of 8.5 g/10 min. The specific activity was 157,000 g of polymer per gram of titanium per hour and per atmosphere of ethylene.

EXAMPLE 21 The procedure of Example 17 was repeated using 1,050 mg (43 milligramatoms) of magnesium, 15 ml (110 milligramatoms) of CgH^Cl and 0.2 ml (0.67 milligramatoms) of TifO-iso-CjHy) in 170 ml of n-octane.

The pressure used was 0.05 mmHg and the temperature used was -50°C.

On completion of the vaporisation of the magnesium, the flask was filled with nitrogen and allowed to stand overnight. Analysis of the suspension gave the following results: Mg:Ti ratio - 52; Ci:Ti ratio - SO.

Polymerization of ethylene was carried out under the conditions described in Example 17. There were obtained 125 g of a polymer having an MFI of 6.7 g/10 min, and a specific activity of 75,000 g of polymer per gram of titanium per hour ar.d per atmosphere of ethylene.

EXAMPLE 22 An apparatus similar to that described in Example 1 was used. In the tungsten filament there were arranged 1.096 g of pure metallic magnesium wire. The one-litre flask was charged with 130 cc of anhydrous ligroin containing 1 millimol of TiCl4 together with 66.7 miliimols of SnCl^. The magnesium was completely vaporised in 40 minutes under 4*018 a vacuum of 0.09 Torr, by keeping the flask in rotation at -60°C to -70°C. The flask was restored to the ambient temperature and stirring was continued for approximately one hour. During this time, the slurry changed colour from dark brown to greyish white. Filtration was carried out on a porous G3 diaphragm» The solid material was washed with anhydrous heptane and reslurried in heptane.

Analysis of the slurry gave the following results: -Ti = 5.77 millimols per litre; Mg = 181 millimoles per litre; 5n = 170 millimols per litre; Cl = 731 miTlimols per litre.

EXAMPLE 23 An apparatus similar to that described in Example 1 was used. In the tungsten filament there was arranged KO g of pure magnesium wire. The flask was charged, in the order given, with 130 ml of anhydrous toluene and 1 millimol of TiCl^, which imparts a yellow hue to the solvent. Then, there were added, dropwise at -78°C, 2 millimols of di-ethyTphthalate.

The solution changed colour from yellow to light green. There were then added 66.7 millimol of anhydrous SnCl^, which imparts a yellow-orange hue to the solution. An orange oily substance settled on the flask bottom.

The magnesium was vaporised in 40 min at 0.05 Torr and at -78°C, while maintaining the flask in rotation. The flask was brought back to ambient temperature and pressure and kept stirred for about one hour. During this time the slurry changed colour from dark brown to yellow. The slurry was collected on a filter, and the solid material was washed with anhydrous heptane and reslurried in heptane.

Analysis of the slurry gave the following results: Ti = 7.74 millimols per litre; Mg = 235 millimols per litre; Sn = 190 millimols per litre; Cl = 897 millimols per litre. . 43013 EXAMPLE 24 An apparatus similar to that described in Example 1 was used. In the tungsten filament there were placed 809.5 mg of pure magnesium wire. The flask was charged with 100 ml of anhydrous toluene and one nrillimol of TiCl^, which gave the solvent a. yellow colour. Then, there were added at room temperature and with stirring 2 millimols of di ethyl phthalate.

The colour of the solution changed to light green. There were further added 43.3 millimols of SnClg, which imparted a yellow-orange hue to the solution. An oily substance was deposited on the flask bottom. The magnesium was evaporated in 40 minutes under a vacuum of 0.07 Torr while maintaining the flask in rotation at -78°C. The flask was brought back to ambient pressure and temperature and stirring was continued for about 2 hours at room temperature. The slurry changed colour from dark brown to light grey during this period of time. Filtration, washing with anhydrous heptane and reslurrying in heptane were carried out.

EXAMPLE 25 An apparatus similar lo that described in Example 1 was used. 970 mg of pure magnesium wire were placed on the tungsten. To the flask, containing 100 ml of anhydrous heptane and 1 millimol of TiCl^, there were added at room temperature and with stirring 60 nt,illimols of distilled SbClg. The solution remained clear. By vaporising the magnesium, the suspension became yellow-brown. Then there was formed a white powder which gradually darkened to become grey and eventually black. Filtration, washing with anhydrous heptane and reslurrying in heptane were carried out.

Analysis of the slurry gave the following results: Ti = 4.60 millimols per litres Mg = 226 millimols per litre; Sb = 95 millimols per litre; Cl = 1,058 millimols per litre. 4¾°18 EXAMPLE 26 An apparatus similar to that described in Example 1 was used. There were placed on the tungsten filament 831.8 mg of pure magnesium wire.

To the flask, containing 100 ml of anhydrous n-heptane, there were added, at room temperature and with stirring, 51.3 millimols of distilled PQCJ and 1 millimol of TiCJ, ' A yellow precipitate formed. The magnesium was vaporised while keeping the flask at -78°C. The suspension changed colour to yellow-brown. The flask was brought back to ambient temperature and pressure and stirring was continued for 2 hours at room temperature. The suspension became pale yellow. Filtration, washing with n-heptane and reslurrying in n-heptane were carried out.

Analysis of the slurry gave the following results: Ti = 9.62 millimols per litre; Mg = 126 millimols per litre; P = 390 millimoles per Titre; Cl = 655 millimols per litre.

. EXAMPLE 27 Ethylene polymerization tests using the catalyst mixtures prepared according to Examples 22 to 26 were carried out according to Example 17 with a polymerization time of 2 hours, a pressure of hydrogen of 2 5 kg/cm and a pressure of ethylene of 5 kg/cm . The results obtained are tabulated in Table 3.

TABLE 3 Catalyst (Example No.) Specific activity (grams of polymer per gram of Ti per hour and per atmosphere pf ethylene) mfi2i (g/ΙΟ min) mfi21 «^1 Apparent specific gravity (g/cnl3) 22 34,700 5.00 36 0.30 23 32,500 5.70 31 not determ. 24 13,000 2.90 32 h il 25 34,000 6.98 27 0.20 26 8,300 4.32 31 not determ. 4··5β1β EXAMPLE 28 A two-necked flask, purged with nitrogen, was charged with 10 g of powdered polyethylene, 50 ml of anhydrous and deaerated n-hexane and 1.5 milligramatoms of Al(iso-Bu)3Upon homogenization, the mixture was allowed to stand for two hours, whereafter there were added, under a nitrogen stream, 0.0075 milligramatoms of the co-catalyst prepared as disclosed in Example 17 together with 1.5 milligramatoms of Al(iso-Bu)3. The hexane was completely distilled off in vacuo at 60°C. The material thus prepared was charged under nitrogen into a well dried 1-litre autoclave which had been deaerated and kept under a nitrogen atmosphere. The autoclave was evacuated to remove nitrogen, whereafter ethylene was fed in until reaching a gauge pressure of 1.5 kg/cm2. The temperature was raised to 80°C. During polymerization, ethylene was fed in so as to keep constant the gauge pressure of 1.5 kg/cm . The absorption of ethylene was checked by a rotameter. Polymerization was discontinued after 5 hours. During this period of time the absorption remained constant. There were obtained 84 g of polyethylene, corresponding to a specific activity of 16,500 g of polymer per gram of titanium per hour and per atmosphere of ethylene.

EXAMPLE 29 The procedure disclosed in Example 28 was repeated, using 2 kg/cm2 of hydrogen as a molecular weight adjuster. After three hours of polymerization, there were obtained 56 g of a polymer having an MFI of 2.1 g/10 min.

EXAMPLE 30 Copolymerization of ethylene with butene-1 was carried out, using the catalyst disclosed in Example 17 and also the procedure, polymerization conditions and concentrations of catalyst as described in Example 17. The introduction of butene-1 was carried out concurrently with that of ethylene, the quantity of butene-1. introduced being equal to 5% of that of ethylene, the gases being metered with calibrated fluxmeters. After one hour of polymerization, there were obtained 290 g of a copolymer having an MFI of10 g/10 min and an apparent specific gravity of 0.9580 g/cm? The speeific activity was 170,000.g of copolymer_per gram of titanium per hour and per atmosphere of ethylene.

; EXAMPLE 31 Copolymerization of ethylene with hexene-1 was effected using the catalyst described in Example 17 under the same conditions and concentrations as disclosed in Example 17. The procedure was as follows. An autoclave was charged with 1.8 litres of n-heptane containing 8 g of anhydrous and deaerated hexene-1. The temperature was thermostatically maintained et 85cC. The-catalyst system was 4 miliimols of Al(iso-Bu)3 and the co-catalyst of Example 17 in an amount of 0.01 miliimols of titanium, diluted with 200 ml of n-heptane. The autoclave was charged with hydrogen to a partial pressure 2 of 5 kg/cm and ethylene- to a partial pressure of 3.5 kg/cm . During the feeding of ethylene, which was carried out continuously for the entire poly20 merization time (1 hour) to keep constant the total pressure, there were also fed in 8 g of hexene-1 diluted in 100 ml of n-heptane, by a metering pump. After one hour of polymerization- the gases were vented off, the copolymer was collected on a' filter and dried. There were obtained 230 g of a copolymer having an MFI of 8.5 g/10 min and an apparent specific gravity of 0.9576 g/cm . The specific activity was 136,000 g of copolymer per gram of titanium per hour and per atmosphere of ethylene.

Claims (18)

1. A process for preparing a co-catalyst for use in the polymerization of an α-olefin with itself or with a monomer copolymerizable therewith, which process comprises vaporising a metal and reacting the resulting vapour with a compound of titanium or of vanadium in the presence of a halogen donor, the reaction being carried out in an inert carbonaceous diluent.

2. A process according to claim 1, wherein the metal vapour is reacted with a trivalent titanium compound, a tetravalent titanium compound or an organo-titanium compound.

3. A process according to claim 2, wherein the metal vapour is reacted with TiCl^.

4. A process according to claim 1, wherein the metal vapour is reacted with VC 1^.

5. A process according to any of claims 1 to 4, wherein the metal which is vaporised is magnesium, a magnesium-containing alloy, aluminium, chromium, manganese, iron, vanadium or titanium.

6. A process according to any of claims 1 to 5, wherein the compound of titanium or vanadium also acts as the halogen donor.

7. A process according to any of claims 1 to 6, wherein the halogen donor is an organic or inorganic halide.

8. A process according to any of claims 1 to 7, wherein the vaporisation of the metal is carried out at a pressure of from IO' 6 Torr to 760 Torr.

9. A process according to claim 8, wherein the vaporisation of the -β -1 metal is carried out at a pressure of from 10 to 10 Torr.

10. A process according to any of claims 1 to 9, wherein the vaporisation of the metal is carried out at a temperature of from 300 to 1200°C.

11. A process according to any of claims 1 to 10, wherein the , reaction is carried out-at a temperature of from -80 to 20°C.

12. - A process according to claim IT, wherein the reaction is carried out at a temperature of from -60 to -20°C. 5

13. A process according to any of claims 1 to 12, wherein the inert carbonaceous diluent is selected from aliphatic saturated hydrocarbons, aliphatic unsaturated hydrocarbons, aromatic hydrocarbons and halogenated hydrocarbons.

14. A process according to any of claims 1 to 13, wherein the initial 10 atomic ratio of halogen donor to the metal is 2:1 or more.

15. A co-catalyst for use in the polymerization of an α-olefin with itself or with a monomer copolymerizable therewith, when prepared by a process according to any of claims I to 14.

16. A catalytic’ system for use in the polymerization of an a-olefin 15 with itself br with a monomer copolymerizable therewith, th.e system comprising first and second co-catalysts, the first co-catalyst being a co-catalyst as claimed in claim 15 and the second co-catalyst being an organo-alumini urn compound.

17. A catalytic system according to claim 16, wherein the organo20 aluminium compound has the formula AIRnXg-n, wherein R is a hydrogen atom or hydrocarbon, radical, X is a halogen atom, and £ is 1, 2 or 3. T8. A process for the polymerization of an α-olefin with itself or with a monomer copolymerizable therewith, wherein the polymerization is carried out in the presence of a catalytic system according to claim 16 or 17 25 19. A process according to claim 18, wherein the polymerization is effected at a temperature in the range of from 20°C to 200°C. 20. A process according to claim 18 or 19, wherein ethylene is polymerized with itself or with a monomer co-polymerizable therewith, and wherein the polymerization is effected at a partial pressure of ethylene in the range of from 1 to 20 atmospheres. 21. A process according to any of claims 18 to 20, wherein the % polymerization is carried out in the presence of an inert diluent. 22. A process according to claim 21, wherein the inert diluent is a hydrocarbon or halogenated hydrocarbon. 23. A process according to any of claims 18 to 20, wherein the a-olefin and, if used, the monomer copolymerizable therewith are fed to the catalytic system in the gaseous phase and polymerized in the absence of solvent. 24. A process according to claim 23, wherein the catalytic system is dispersed on an inert support. 25. A process according to claim 23 or 24, wherein the polymerization is carried out under a pressure in the range of from 1 to 60 atmospheres. 26. A process according to claim 23, 24 or 25, wherein the polymerization is carried out at a temperature in the range from room temperature to a temperature below the melting point of the polymer being produced. ' I 27. A process according to claim 1, substantially as described in any of the foregoing Examples 1 to 8 and 17 to 26. 28. A catalytic system according to claim 16, substantially as described in any of the foregoing Examples 9 to 21 and 27 to 31. 29. A process according to claim 18, substantially as described in any of the foregoing Examples 9 to 21 and 27 to 31. 31. A co-catalyst when'prepared by a process according to claim 27. 31. A polymer when prepared by a process according to any of claims

18. To 26 and 29.