GB1569995A - Catalyst components for polymerisation of olefins - Google Patents

Description

(54) CATALYST COMPONENTS FOR POLYMERISATION OF OLEFINS (71) We, SOCIETE CHIMIQUE DES CHARBONNAGES, a Societe anonyme organised under the laws of France, of Tour Aurore Cedex 5,92080 Paris la Defense, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The present invention relates to catalyst components for use in the polymerisation of a-olefins, to a method for the preparation of these catalyst components and to a method for the polymerisation of colefins from catalyst systems including these catalyst components.

The polymerisation of cokfins in the presence of a catalytic system comprising on the one hand, a solid composition of titanium trichloride TiCl3 and possibly syncrystallised aluminium chloride AlCl3 and on the other hand, an organo-aluminium activating compound is well known. The chemical formula and physical structure of the Tics3 - AIR13 composition are decisive factors for the performances of yield and stereo-specificity of the methods for the polymerisation of ar-olefins using such systems. Several methods for the physical and chemical treatment of the TiCi3 AIC13 compositions have thus been proposed for improving these performances. Thus, British Patent No. 1,087,314 describes grinding together, at a temperature less than 80 , the mixed titanium and aluminium chloride Tic3.

1/3 AlCl3 and a monoether present in an amount of 0.03 to 1 mole/mole TiCl3. On the other hand, British Patent No. 1,370,559 describes the treatment of the mixed chloride at a temperature of between 0 C and 80"C, with an ether added in an amount of 1 to 5 moles/mole TiCl3, followed by a reaction with titanium tetrachloride at a temperature of between -300C and +1350C and preferably between 40"C and 700C, a reaction which is advantageously carried out in the presence of an inert diluent, preferably an aliphatic hydrocarbon. This method makes it possible to increase the catalytic activity from 40% to 55S and to achieve stereospecificity, measured by the percentage of polymer insoluble in hexane.

of 95% to 96% for polypropylene. Finally, French Patent No. 2,151,113 describes the reaction at a temperature of between 30 and 100"C, necessarily in a hydrocarbon, of the ground mixed chloride with an ether present in an amount of 0.006 to 0.7 moles/mole TiC13. This method makes it possible to increase the catalytic activity from 40% to 702 and to achieve stereospecificity, measured by the amount of polymer insoluble in hexane of 97% to 99% for polypropylene.

These methods improve the yield and sterec speciticity of the methods for the polymerisation of colefins, but on the one hand, they involve an intricate and long-drawn treatment and on the other hand, they lead to polymers having an isotacticity, which is still insufficient for numerous applications. The object of the invention is therefore to purpose a simplified physico-chemical treatment of the TiCl3 AIR13 compositions used in catalytic systems for the polymerisation of or-olefins, whilst improving the yield and stereospecificity of this polymerisation.

According to the present invention there is provided a catalyst component of formula TiClS (AlCl3) x (E,TiCl4)y wherein xis from 0.08 to 0.19, E is an ether which forms complex (E,TiCl4) soluble at 550C in titanium tetrachloride or an aromatic hydrocarbon and y is from 0.003 to 0.03, the catalyst component having, in its X-ray diffraction spectrum, lines corresponding to planes of lattice distance 1.755 A, 2.665 A and 5.81 A and whereof the dimension of the crystallites along the axis of symmetry corresponding to the lattice distance 5.81 A is from 190 A to 260 A.

Preferably the ether E is diisoamyl ether or di-n-butyl ether.

The method of preparation of the catalyst components according to the invention comprises reacting the mixed titanium and aluminun chloride TiCl3 1/3 AlCl3 of A-crystalline form (according to the classification adopted by the Journal of Polymer Science - 51 - 403) preactivated by grinding and a complex of titanium tetrachloride and of an ether E as defined above, said complex being in solution in titanium tetrachloride or an aromatic hydrocarbon and the reaction temperature being between 55 C and 1300C, preferably, between 70" and 115"C.

The mixed chloride TiCl3, 1/3 AlCl3 of A crystalline form used in the method according to the invention is a product of disordered crystalline structure obtained in known manner by grinding. The conditions under which the mixed chloride is ground are not critical and do not affect the catalyst components of the invention.

The complex used in the method according to the invention is a complex, preferably a 1:1 complex, formed between titanium tetrachloride TiCl4 and an ether, the ether being one which produces with the titanium tetrachloride a complex which is soluble at 55 0C in titanium tetrachloride or an aromatic hydrocarbon . The ether is preferably diisoamyl ether (D.LA.E.) or di-n-butyl ether (DNB.E.), and it has in fact been found that diethylether, diphenylether diisopropylether and methyltertbutylether are not so convenient for the working up of the process according to the invention. The molar ratio DIAE or DNBE (when either DIAE or TiCl4 TiC14 DNBE is used as the ether E) is preferably between 0.05 and 1, and the complex is used in solution either in titanium tetrachloride or in an aromatic hydrocarbon such as toluene.

It should be noted that the complexation reaction does not proceed to completion so that in the case where the molar ratio DIAE or TiCl4 DNBE is 1, T will be present in the product TiCl4 to act as solvent for the complex. Such a pro duct may be used without additional sovent.

The molar ratio DIAE or DNBE is preferably TiC13 TiCl3 between 0.05 and 8 and the molar ratio TiCll TiC14 is preferably between 0.1 and 3.

Contrary to the two-stage method of British Patent No. 1,370,559, in which the total duration of treatment, outside the intermediate operation of washing, is never less than 75 minutes the method according to the invention for preparing catalyst components offers the advantage that it may be effected in a time of 1 to 60 minutes and preferably in a time of between 2 and 15 minutes.

The invention makes it possible to provide catalyst components having a surface area greater by a factor 35 than the mixed titanium aluminium chloride. This is substantially highe than methods of the prior art. For example, this factor is equal to 2.5 in British Patent No.

1,370,559. This comparison of relative values I is most significant, since it is known that the absolute values of surface areas are strongly influenced by the nature of the reference cata lyst component and by the conditions of measurement. In addition the microporosity of catalyst components is multiplied by a factor of about 5 by the treatment according to the invention. This fact is particularly im portant in the initial phase of polymerisation where the polymer crystallising in the micro pores promotes the process of fracturing of the crystalline system, followed by the forma tion of new active sites.

The catalyst components of the invention are used jointly with an activating compound of formula AlRn X3 -n to polymerise aolefins.

In the formula A1Rn 3 -n -R is a hydrocarbon radical having 1 to 8 carbon atoms and chosen from alkyl, aryl, cycloalkyl, arylalkyl and alkylaryl radicals.

-X is a halogen atom or trialkyl-siloxy group -n is any number such that 0 < n < 3.

Trialkylaluminiums and monohalogenodi alkylaluminiums constitute effective activating compounds. The molar ratio of the activating compound to the catalyst component of the invention is in known manner preferably between 0.5 and 10 and may be determined depending on the aolefin to be polymerised and other operating conditions, using prior knowledge of the man skilled in the art.

The catalyst components of the invention and the activating compound constitute cala lytic systems suitable for the polymerisation of anlefins at pressures of between 1 and 2,500 atmospheres and at temperatures of between 0 and 350"C. The polymerisation method is effected with aolefins comprising 2 to 8 carbon atoms, such as ethylene, propy lene, 1-butene, 4-methylpentene, l-hexene and vincylcyclohexene. By extension, the method of polymerisation according to the invention may be used for the preparation of copolymers of two of these aolefins as well as with diolefins such as butadiene, isoprene, ethylidenenorbornene, dicyclopentadiene, 4-vinyl-cyclohexene. The choice of the conditions as regards temperature and pressure in each case is within the scope of a man skilled in the art: thus, the aforesaid aolefins may all be polymerised at a temperature of 0 to 1200C under 1 to 50 atmospheres and ethylene may also be polymerised at a tem perature of 120 to 3500C at a very high pressure of 300 to 2,500 atmospheres. In the latter case, the catalyst components of the invention may be advantageously ground with magnesium chloride before being activated with the orgonoaluminium compound and used in the polymerisation reaction.

The polymerisation method according to the invention may use any one of known techniques and may be continuous or discontinuous: eg. the solution method, suspension method in a diluent, or mass polymerisation in the liquid or gaseous phase may be used. For the polymerisation of ethylene at very high pressure, an autoclave or tubular reactor may be used. In known manner, the molecular weight of the polymer may be adjusted by maintaining a certain pressure of hydrogen in the reaction medium. The isotacticity of polymers obtained by means of the catalytic systems of the invention may be further increased by the introduction to the reaction medium of known additives such as furfural, 2-pyrrolealdehyde, 2-N-methylpyrrole aldehyde (British Patent No.

1 Al 0,106), hydrazine and 1, l-dimethylhydra- zine (U.S. Patent No. 3,907,761), ethyl benzoate, hexamethylphosphorictriamide, cycloheptatriene and trimethylphosphine. If the polymerisation is to be effected in an autoclave then, in known manner, the catalyst may be pre-polymerised with an a-olefin in an a-olefin TICS3 ratio of 0.5 to 30 to prevent decantation in the injection circuits of the autoclave.

The above described catalyst systems give improved yields in the polymerisation reaction as compared to the yields obtained with conventional catalyst systems. The improvement in yield may reach 125% in the case of propylene, and generally the stage of eliminating the catalytic residues is unnecessary. The catalyst systems also make it possible to achieve a stereospecificity, measured by the precentage of polymer which is insoluble in heptane, which is 91 to 97% for polypropylene.

As explained above, the activity of the catalyst components of the present invention is only greater than that of commercial catalysts, but also greater than that of cqmmercial catalysts treated according to methods of the prior art. In order to compare the activity of catalyst systems used in different polymerisation processes and in particular in processes of varying duration carried out at different pressures, it is well known to express said activity (a) in grams of polymer per gram of TiCl3 contained in the catalytic system, per hour and per atmosphere. In the case of polypropylene, it has thus been found that a commercial catalyst having an activity of 58 achieved an activity of 89 when treated according to the method of British Patent No. 1,370, 559 and an activity of 120 when treated according to the method of the invention.

Finally, ageing of the catalyst components according to the invention is accompanied by a slight reduction in activity and by retention or improvement of the stereospecificity. This is in contrast to commercial catalysts which on ageing, show improved activity accompaniec by a sudden decrease of the stereospecificity which renders them unsuitable for producing numerous types of polymers.

The following examples serve to illustrate the invention. In the Examples, the dinoamy- lether or di-n-butylether may be replaced by any ether able to form with TiCl4 a complex soluble at 550C in titanium tetrachloride or an aromatic hydrocarbon.

EXAMPLE 1 A mixed titanium and aluminium chloride TiCl3 1/3 AICl3 of Acrystalline form sold by TOHO TITANIUM under the Trade Name TAC 191 is pre-activated by grinding and suspended in titanium tetrachloride in a Pyrex (Registered Trade Mark) glass container in the presence of dinoamyl ether (DIAE). The molar ratios of the constituents of the suspension are DIAE = 1 and DIAE = 0.15. The TiCl3 TICS4 titanium tetrachloride is used without special purification, whereas the ether has been dried using a molecular sieve and distilled over calcium hydride. The suspension is magneticall stirred and rapidly heated to the temperature T for a time of 15 minutes. At the end of the operation, the catalyst component is separated then washed three times at 200C by being placed in suspension in heptane at a concentration of 0.25 to 2 moles/litre and immediately activated by monochlorodiethylaluminium in a molar ratio 1:1, in order to stabilise its structure The heptane used has been de-gassed by bubbling nitrogen through the heptane, dried on a molecular sieve column and distilled over lithium aluminiumhydride, whereas the activator has not been subjected to special purification.

Dry and purified heptane, the catalyst system and propene purified over activated alumina and a molecular sieve are introduced successively into a 0.5 litre flask which is dry and has been purged by means of nitrogen until atmospheric pressure is reached at 60 C.

This pressure is kept constant during polymerisation by the introduction of gaseous propylene. After 1 hour of polymerisation, the contents of the flask are poured onto a Buchner filter without de-activation of the catalyst and without washing. The polypropylene powder retained by the filter is dried to give a constant weight by evaporation of the solvent. The soluble parts are recovered and dried to give a constant weight. The percentage of insoluble polymer is determined by taking into account the activating agent carried over with the soluble parts. In Table I, the catalytic activity a is expressed in grams of polypropylene per gram of TiCl3 , per hour and per atmosphere and the stereospeci ficityfis expressed as the percentage of polymer insoluble in heptane at 600 C.

Test 1 corresponds to the commercial reference product which has not undergone any treatment. Furthermore, the surface area measured by means of a PERKIN-ELMER 212 D adsorptometer calibrated according to BS standard 4359/1 is 69m2 /g for test 4 against only 21m2/g for test 1. The porosity, defined by the volume of micropores of diameter less than 200A and measured by means of a TABLEI

Test 1 2 3 4 5 6 7 8 T"C - 55 65 75 85 95 105 115 a 58 77 105 113 115 106 99 90 94.0 88.5 90.5 939 95.0 953 949 93.9 CARLO ERBA mercury porosimeter (CARLO ERBA is a Registered Trade Mark), is 0.115cm3/ g for test 4 against only 0.023cm /g for test 1.

The catalyst components produced in Tests 2-8 are all covered by the formula TiCl3 (AIC13) x (DIAE, TiCl4 )y where x and y are defined above. Additionally the catalyst components of Tests 2 - 8 all have in their X-ray diffraction spectra lines corresponding to planes of lattice distance 1 .755A, 2.665A and 5.81A and the dimension of the crystallites along the axis of symmetry corresponding to the lattice distance 5.8 A is from 1 90A to 260A. More specifically the structure determined by means of the X-ray diffraction spectrum of the catalyst components tests 5 and 6 is compared below with that of the reference product (test 1). The characteristic lines of this spectrum correspond to planes of lattice distance 5.81 A and 1.755 A and make it possible to calculate by the Scherrer formula thesdimensions of crystallites along the hexagonal axis of symmetry (c) and in the direction at right-angles to this axis (a) (Journal of Catalysis - 28 - 351). The results of these measurements are given in Table II.

TABLE II

Test | 1 | 5 | 6 c(A) 308 210 228 a(A) 412 520 490 EXAMPLE 2 The mixed titanium and aluminium chloride TAC 191 is treated according to the same sequence of operations as in tests 2 to 8 and the polymerisation test of propylene is also carried out under identical conditions. Nevertheless, the molar ratios DIAE and DIAE and TiC13 TiCl4 the durations t have been modified and are given in Table III.

The catalyst components produced in Tests 9 - 14 are all covered by the formula TiCl3 (AICl3)x (DIAE, TiC14) where x and y are as defined above. Additionally the catalyst components of Tests 9 - 14 all have in their X-ray diffraction specra lines corresponding to planes of lattice distance 1.755 A, 2.665 A an 5.81 A and the dimension of the crystallites along the axis of symmetry corresponding to the lattice distance 5.81 A is from 190 A to 260 A.

EXAMPLE 3 The mixed titanium and aluminum chloride TAC 191 is treated under the conditions of test 6 but replacing the diisoamyl ether by di-n-butyl ether (DNBE). The catalyst component produced falls within the formula Tics3 (MCl3)x (DNBE, TiC14)y where x and y are as defined above. The X-ray diffraction spectrum of the catalyst component has lines corresponding to planes of lattice distance 1.755 A, 2.665 A and 5.81 A,andthedimen- sion of the crystallites along the axis of symmetry corresponding to the lattice distance 5.81 A is from 190 A to 260A. The polymerisation test of propylene is carried out as in Tests 2 to 8. A catalytic activity a of 85 and a stereospecificity {,of91.1 are obtained.

EXAMPLE 4 The titanium and aluminum chloride TAC 191 is pre-actuated by grinding and suspended in the presence of diisoamyl ether in a mixture of titanium tetrachloride and toluene, the ratio of volume TiCl4 being equal to 0.7.

toluene Toluene is used which has been de-gassed by bubbling nitrogen through the toluene, dried on a molecular sieve column and distilled over lithium aluminiumhydride. The treatment is then carried out at 850C under the conditions of tests 2 to 8, with the exception of the heating time which is increased to 60 minutes.

The catalyst component obtained is covered by the formula TiCl3 (AICl3)x (DIAE, TiC14)y where x andy are as defined above.

The catalyst component has in its X-ray diffraction spectrum lines corresponding to planes of lattice distance 1.755 A, 2.665 A and 5.81 A, and the dimensions of the crystallites along the axis of symmetry corresponding to the lattice distance 5.81 A is from 190 A to 260 A.

At the end of the polymerisation test of propylene, carried out as in the preceding examples, a catalytic activity a of 120 and a stereospecificity6 > of 92.0 are found.

TABLE III

Test rc DIAE DIAE timing a TiCl3 TiCI4 9 95 0.5 0.075 15 92 92.6 10 95 3 0.45 15 97 93.7 11 95 1 1 15 108 93.8 12 95 0.075 0.15 15 110 93.8 13 95 1 0.15 6 92 95.0 14 100 1 1 2 1-16 94.1 EXAMPLE 5 The catalyst component prepared under the conditions of test 5 of Example 1 is used jointly with an activating agent of formula Al(C8 Hl 7 )3 to polymerise ethylene at a temperature of 260'C and at a pressure of 1500 atmospheres. The activating agent is used in an atomic ratio Al equal to 3 and the residence Ti time in the stirred autoclave reactor is 34 seconds. Under these conditions, the catalytic yield is 2.7 kg polymer per milliatom of titanium. The polyethylene thus obtained has a density of 0.940glcm3, a melt index (measured according to ASTM 1238-62T standard) of 0.5 and a weight average molecular weight of 96000. The amount of l-butene measured in the re-cycling circuits is 2.4% by weight.

EXAMPLE 6 The catalyst component prepared under the conditions of Test 5 of Example 1 is ground for two hours with magnesium chloride then used jointly with the tri-n-octylaluminium activating agent to Polymerise ethylene at a temperature of 260 C and at a pressure of 1200 atmospheres in an autoclave reactor provided with agitation means. The activating agent is used in a quantity such that the atomic ratio A1 is equal to 3. Under these conditions, Ti the catalytic yield is 5.5 kg polymer per atom of titanium. The polyethylene obtained has a density of 0.962glcm" and a weight average molecular weight of 93,000. The amount of l-butene measured in the re-cycling circuits is 2.2% by weight.

EXAMPLE 7 Catalyst components according to Tests 1, 5 and 6 of Example 1 are used jointly with the monochlorodiethylaluminium activating agent to polymerise 1 -butene at 600C in solution in methylcyclohexane, the pressure of the 1butene being equal to 0.75 atmospheres and the total pressure being 1.075 atmospheres.

Table IV gives the results of the catalytic activity a in grams of polybut-l-ene per gram of TiCl3, per hour and per atmosphere, the isotacticity measured by the amount of polymer insoluble in boiling diethyl ether.

It should be noted that in the Table the Tests 15, 16 and 17, correspond respectively to the use of the catalyst components of Tests 1, 5 and 6 of Example 1. The Table also reitarates the preparation temperature T of the catalyst components prepared in Tests 5 and 6.

TABLE IV

Test T C a 15 8 83.7 94.8 16 85 112.7 97.0 17 95 117 97.7 EXAMPLE 8 The mixed titanium and aluminium chloride TAC 191 is treated with di-n-butyl ether and TiCl4 according to the sequence of operations of Example 1 at a temperature of 85 C, with the exception of the washing operation, which is carried out at 200C by placing the latter in suspension in a non-inert diluent such as toluene. The molar ratios DNBE and TiCl3 DNBE are varied as shown in Table V, gives TiC14 the results of polymerisation of l-butene in solution carried out according to the conditions of Example 7. Test 15 constitutes a comparison reference with which the results in Table V may be compared.

The catalyst component obtained in this Example is covered by the formula TiC13 (AIC13)x (DIAE, TiCl4)y where x andy are as defined above. Additlonally the catalyst component has in its X-ray diffraction spectrum lines corresponding to planes of lattice distance 1.755 A, 2.665 A and 5.81 A and the dimension of the crystallites along the axis of symmetry corresponding to the lattice distance 5.81 A is from 190 A to 260 A.

TABLE V

Test DNBE DNBE a TiCI3 TiCl4 18 1 0.15 81 DNBE 19 1 1 109 97.2 19 1 1 109 97.2 EXAMPLE 9 The catalyst component prepared under the conditions of Test 5 of Example 1 is used jointly with the monochlorodiethylaluminium activator for mass-polymerising l-butene. 40 litres of monomer are introduced into a 50 litre reactor provided with agitation means comprising a helical band and purged by means of nitrogen, and the monomer is heated to the chosen polymerisation temperature. The 1butene used comprises 100 ppm 1,3-butadiene and, after drying by means of a molecular screen and filtration on glass wool, 6 ppm water. A solution comprising 10 millimoles/ litre of activating agent in methylcyclohexane under hydrogen is introduced into the reactor, then hydrogen is introduced up to the desired partial pressure and finally a suspension of the catalyst element of the invention in methylcylohexane, under nitrogen. After the end of polymerisation, the solution of polybutene in unpolymerised l-butene is sent to the washing reactor, where it is firstly put into contact with 250 ml isopropanol for 30 minutes, then washed twice with 20 litres of water at 600C for 30 minutes. A solution of a mixture of an anti-oxidising and a stabilising agent is then introduced with stirring. The polybutene solution is sent to a 30 litre reactor where the l-butene evaporates and the polymer crystaffises.

It is dried in a ventilated oven at 55 C, then ground and granulated.

The melt index of the polymer obtained is measured according to the ASTM 1238-62T standard and its isotacticity is measured by the amount of insoluble polymer in boiling diethyl ether. The dynamometric properties under traction are determined according to ISO 527 standard with sheets moulded at 180"C by compression and left for 8 days.

The results of tests 20 to 26, in which the partial hydrogen pressure PH2 expressed in atmospheres and the polymerisation temperature T1 are varied, are given in Table VI. The flow strength RR are expressed in kg/cm2, , the elongation on breaking threshold SF and the breaking AR and the isotacticity 6are expressed as a percentage, the melt index IF in g110 mins, the catalytic activity a in grams of l- in the concentrations given in Table IX in order to polymerise l-butene under the conditions of Example 7. An additive, whose nature and concentration are also given, is also added to the reaction medium.

TABLE VII

Test OC PH2 a IF 6 SF RR AR 27 60 0.2 975 1.6 95.8 157 221 175 28 60 0.7 1014 9 87.8 128 208 223 29 60 0.7 1256 4.9 97.6 207 285 251 TABLE VIII

Test Tt C C a SF RUB AT 30 50 0.1 945 99.2 - - - 31 60 0.3 1920 97.1 212 400 320 32 80 0.1 2260 97.0 - - - TABLE IX

Al(C2 Hs )3 M(C2 H5 )2 Cl Additive Test m-mole/l m-mole/l Name m-mole/l a 6t a 33 2.45 11.75 furfural 0.3 148.6 94.9 34 5 0 cyclohe ptatriene 5 190 88.6 35 5 0 Ethyl Benzoate 1.5 311 85.1 36 Ethyl Benzoate 0.6 668 80.6 EXAMPLE 14 The random copolymerisation of l-butene and ethylene is carried out at 600C under the operating conditions of Example 9. Table X gives the molar proportion of ethylene is the monomer mixture, as well as the partial hydrogen pressure and the results obtained such as the activity, isotacticity and breaking strength of the resultant copolymer. Test 37 and 38 use the catalyst components prepared in Tests 1 and 5 respectively.

TABLEX

Test %C2 H4 PH2 &alpha; # RR 37 0.78 0.8 1040 94 4 7 313 38 0.93 0.7 1450 98.2 384 EXAMPLE 15 0.1 millimole furfural per litre of mixture of monomers is added to a 4 litre autoclave reactor having mechanical agitation means, heated to 60 C and containing a quantity b of liquid 1 butene and a quantity p of liquid propene. Then, polymerisation takes place at 600C for 1 hour, under a partial hydrogen pressure of 0.5 bar and by means of a catalytic system comprising 10 millimoles/litre monochlorodiethylaluminium activating agent and 1 millimole/litre of the catalyst component prepared under the conditions of Test 5 of Example 1. The copolymer obtained is deactivated by isopropyl alcohol, then washed with water at 75 C, dried and weighed. The catalytic activity a is thus measured in g/gTiCI3/ hour, the isotacticity # determined by dissolution in boiling diethyl ether, the melt index according to ASTM 1238-62T standard and the molar percentage P of propene units in the copolymer by infrared spectrometry. These results are given in Table XI.

EXAMPLE 16 In a 4 litre autoclave reactor, provided with mechanical agitation means, heated to 650C and containing 1.4 litre l-butene, 0.7 litre propene and 0.7 litre methylcyclohexane, polymerisation is carried out for 2 hours under a partial hydrogen pressure of 0.5 bar and by means of a catalyst system comprising 10 millimoles/litre monochlorodiethylaluminium activating agent and 0.2 millimoles/litre of the catalyst component prepared under the conditions of Test 5 of Example 1. The copolymer obtained is de-activated by isopropanel, washed with water at 75 C, dried and weighed. Its main properties, determined as previously, are as follows: a =990g/gTiCl3/hr < = 39% MI = 67 P = 55% TABLE XI

Test b(Kg) p(Kg) cu a MJ. P% 39 3.85 0.08 1 170 99.5 22 1.5 40 3.91 0.175 1 210 98.5 2A 5.6 41 3.21 0.31 1110 96A 39 17.7 WHAT WE CLAIM IS: 1. A catalyst component of formula TiCl3 (AICl3)x (E, TiCI4) wherein xis from 0.08 to 0.19, E is an ether which forms complex (E, TiC14) soluble at 55 C in titanium tetrachloride or an aromatic hydrocarbon and y is from 0.003 to 0.03, the catalyst component having, in its X-ray diffraction spectrum, lines corresponding to planes of lattice distance 1.755 A, 2.665 A and 5.81 A and whereof the dimension of the crystallites along the axis of symmetry corresponding to the lattice distance 5.81 A is from 190Ato 260 A.

2. A catalyst component according to Claim 1 wherein E is diisoamyl ether or di-n-butyl ether.

3. Method for the preparation of a catalyst component as claimed in Claim 1 wherein a mixed titanium and aluminium chloride TiCl3 1/3 Air13 of A crystalline form which has been pre-activated by grinding is reacted with a complex of titanium tetrachloride and an ether E as defined in Claim 1, said complex being in solution in titanium tetrachloride or in an aromatic hydrocarbon and the reaction temperature being from 55 to 1300C.

4. Method according to Claim 3 wherein the reaction temperature is from 70 to 1 150C.

5. Method according to Claim 3 or 4, wherein the time of reaction is from 1 to 60 minutes.

6. Method according to any one of Claims 3 to 5 wherein the ether is diisoamyl ether (DIAE) or di-n-butylether (DNBE).

7. Method according to Claim 6 wherein the molar ratio DIAE or DNBE is from TiCl4 TiCl4 0.05 to 1.

8. Method according to Claim 7 wherein the molar ratio DIAE or DNBE is from TiCl3 TiCl3 0.05 to 8.

9. Method according to any one of Claims 3 to 8, wherein the reaction is followed by a washing operation comprising placing the catalyst component in suspension in an aromatic hydrocarbon, and subsequently removing the hydrocarbon.

10. A catalyst system for polymerising a-olefins having 2 to 8 carbon atoms comprising a catalyst component as claimed in Claim 1 or 2 activated by at least one activating compound of formula AlRnX3 -n wherein: -R is a hydrocarbon radical having 1 to 8 carbon atoms and chosen from alkyl, aryl, cycloalkyl, arylalkyl and alkylaryl radicals; -X is a halogen atom or trialkyl-siloxy group; -n is any number such that 0 < n < 3.

11. A method of polymerising or copolymerising a-olefins containing 2 to 8 carbon atoms comprising effecting said polymerisation or copolymerisation at a temperature between 0 and 120"C and at a pressure between 1 and 50 atmospheres by means of a catalyst system as claimed in Claim 10.

12. Method according to Claim 11 wherein the a-olefin is mass-polymerised in the liquid phase under pressurised hydrogen.

13. Method according to Claim 11 wherein the polymerisation takes place in suspension in a diluent.

14. A method of polymerising ethylene comprising effecting the polymerisation at a temperature between 120 and 3500C and a pressure between 300 and 2,500 atmospheres by means of a catalyst system as claimed in

Claims (1)

1. Claim 10.

   15. Method according to Claim 14 wherein the ethylene is mass-polymerised in the gaseous phase.

   16. Method according to Claim 14 or 15 wherein the catalyst system used is one in which the catalyst element was ground with magnesium chloride prior to its activation.

   17. Method according to any one of Claims 11 to 16 wherein the polymerisation medium comprises an additive chosen from furfural, hydrazine, l,l-dimethyl-hydrazine, 2-pyrrole aldehyde, 2.N-methylpyrrole-aldehyde, cycloheptatriene, ethyl benzoate, hexamethylphosphorictriamide and trimethylphosphine.

   18. Method according to any one of Claims 11 to 17 wherein the activating compound is monochlorodiethylaluminium.

   19. Method according to any one of Claims 11 to 17 wherein the activating compound is a trialkylaluminium.

   20. A catalyst component as claimed in Claim 1 substantially as hereinbefore described with reference to any one of the Examples.

   21. A method as claimed in Claim 3 for the preparation of a catalyst component substantially as hereinbefore described with reference to any one of the Examples.

   22. A catalyst system as claimed in Claim 10 substantially as hereinbefore described in any one of the Examples.

   23. A method as claimed in Claim 11 or Claim 14 for the polymerisation of olefins substantially as hereinbefore described with reference to any one of the Examples.

   24. A polyolefin when produced by the method of any one of Claims 11 to 19 or Claim 23.