DE2352154B2 - Process for the low pressure polymerization of ethylene - Google Patents

Description

or

MgO-Al ₂ O ₃₁ SiO ₂ -Al ₂ O ₃

10

15th

25th

30th

MgO • SiO ₂ • Al ₂ O ₃

as a carrier whose internal porosity is above 03 cm ³ / g and whose specific surface area is above 100 mVg, which can optionally be halogenated and on which a magnesium compound is fixed

as well as in the presence of hydrogen as a molecular weight regulator,

characterized in that polymerization is carried out in the presence of catalysts, in the production of which a MagnesiuRihalogenid, a hydrated magnesium chloride or a magnesium phenoxide or alkoxide, the organic radicals of which have 1 to 6 carbon atoms, was used in such an amount as the magnesium compound that the amount of deposited on the porous support of magnesium compound is between 1 · ΙΟ- ³ and 5 ■ ΙΟ- ³ mg-atoms of magnesium per m ² of the specific surface area is of the porous support.

2. The method according to claim 1, characterized in that the magnesium compound on the porous carrier in the form of a mixture with an oxygen-containing, organic titanium compound of general formula

[TiO "(OR),] _ra ,

where R is an organic radical having 1 to 20 carbon atoms, χ and / are any numbers of x> 0 and y> 0 that take the valency of titanium into account, and m is an integer.

60

It is already known to use catalysts for the low pressure polymerization of olefins, the one Contain transition metal compound and an organometallic compound.

The transition metal compound is also known on oxide supports with a large pore volume, such as aluminum oxides (cf. laid out documents of the Belgian patent 7 68271) and halogenated aluminum oxides (see documents laid out in Belgian patent 7 73 227).

The catalysts obtained in this way are very active when compared with those at which the transition metal compound is used as such. They lead to polymers, which are characterized by a broad molecular weight distribution and are free from long-chain branches which makes them particularly suitable for further processing by blow molding.

However, these previously known catalysts have a significant disadvantage. You will namely mostly used in polymerization processes of olefins which, in the presence of a molecular weight regulator, which is almost exclusively hydrogen. It was also found that these systems catalyze the hydrogenation of olefins a non-negligible part of that to be polymerized Olefins are therefore converted into the corresponding, saturated hydrocarbon, whereby the economic viability of the process is jeopardized. On the other hand, these catalysts produce polymers with a very high average molecular weight To reduce this average molecular weight one therefore forced to increase the hydrogen concentration in the polymerization medium and / or the Carry out polymerization at a higher temperature. However, these two measures have the harmful one The result is that the degree of hydrogenation of the olefin to be polymerized is further increased.

In the process of DE-OS 2109 273, ethylene is polymerized in the presence of hydrogen and catalysts from organoaluminum compounds and a catalyst component which has been produced from porous aluminum oxide, on which ethylmagnesium chloride has been fixed, and titanium tetrachloride relatively low average molecular weight In the process of DE-AS 17 70 726, ethylene polymerization in the presence of hydrogen and catalysts made from an organoaluminum compound and a solid catalyst _{component based on aluminum oxide Mg (OH) 2} and TiCU also have very narrow polymers Molecular weight distribution suitable for injection molding processing. If the polymerization of hydrogen-containing ethylene mixtures according to DE-OS 21 37 872 is carried out in the presence of catalysts composed of organoaluminum compounds and a catalyst component composed of a magnesium chloride-aluminum oxide mixture and 3 TiCi ₃ · AlCl ₃ , polymers with a relatively low level for injection molding are also formed suitable molecular weight.

The invention now relates to a process for the low-pressure polymerization of ethylene or for Low pressure copolymerization of ethylene and olefins with 3 to 6 carbon atoms in the presence of Catalysts off

a) an aluminum trialkyl, aluminum hydride or alkylaluminum halide, the alkyl radicals of which are straight-chain or are branched and contain 1 to 20 carbon atoms, or a reaction product of said aluminum trialkyls or alkylaluminum hydrides with isoprene and

b) a solid catalyst complex, which by reaction of a halide, oxyhalide or

Alkoxyhalide one of the metals titanium, vanadium, zirconium or chromium with a porous Aluminum oxide or a porous complex oxide of the formula>

or

MgO · Al ₂ O ^ SiO ₂ · Ai ₂ O ₃
MgO - SiO ₂ · Al ₂ O ₃

as a carrier whose internal porosity is above 03 cmVg 'and whose specific surface area is above 100 mVg, which may be may be halogenated and on which a magnesium compound is fixed, was obtained as well as in the presence of hydrogen as a molecular weight regulator,

in which the disadvantages of the above-mentioned known processes are avoided and polymers with a broad molecular weight distribution and with a relatively high average molecular weight are obtained, which are suitable for extrusion and blow molding when polymerized in the presence of catalysts, when they are produced as a magnesium compound a magnesium halides, a hydrated magnesium chloride or a magnesium phenoxide or alkoxide, whose organic radicals having from 1 to 6 carbon atoms, was used in an amount such that the amount of the deposited on the porous support of magnesium compound is between 1 · ΙΟ- ³ and 5 x IO ³ mg atoms of magnesium per m ^{2 of} the specific surface area of the porous support

The internal porosity of the support oxides used to produce the catalysts used according to the invention, measured by the procedure known under the designation BET method - see S. Bru η auer, P. Em me tt and E. Tel ler in J. Am . Chem. Soc, Vol. 60 (1938), pp. 309-319 - is above 03 cmVg and preferably above 0.7 cm ³ / g. Excellent results are obtained with porous oxides whose internal porosity is above 1 cmVg.

The porous oxides used have a specific surface area above 100 mVg, more often in the order of 200 to 40OmVg. These specific surfaces are according to the above BET method described measured, the one described in British Standards BS 4359, Part 1 (1969) standardized method is applied.

The grain size of the porous oxides used does not affect the productivity of the catalyst. the end For reasons of easier handling, however, the use of particles is preferred, their medium Diameter is between 1 and 500 microns and preferably between 40 and 200 microns. the The morphology of the polymer and its flowability are, however, improved when using porous oxides regular particle shape and narrow grain size distribution. Excellent results will be obtained with porous oxides, the mean diameter of the particles of which is close to 100 microns and whose diameter distribution is narrow.

The exact chemical structure and the method of manufacture of the porous oxides used are not critical provided that they conform to the above.

The aluminum oxides can be produced by all known methods, examples are:

- by pyrolysis of aluminum oxide hydrates, aluminum hydroxides or aluminum salts at increased Temperature;

- by precipitation of soluble, dissolved in water Aluminum salts such as nitrate and chloride in the presence of an alkaline compound such as Ammonia and pyrolysis of the gel obtained in this way.

Particularly suitable aluminum oxides are the activated aluminum oxides which have been produced by pyrolysis of aluminum oxide hydrates at elevated temperature (see the laid-out documents of Belgian patent 7 68 271). Excellent results are obtained with activated aluminum oxides which have an internal porosity above 1 cmVg and were produced from the α-monohydrate by heating to 700-80O ⁰ C for 4 to 24 hours.

Suitable complex oxides include sillimanite Al ₂ O ₃ ■ SiO ₂ and spinel MgO - Al2Q3

The synthetic complex oxides can be produced by known methods. For example, the working technique called mixed precipitation always gives satisfactory results. she consists therein, the soluble salts of aluminum and the other metals in solution in water in the quantities to resolve that the desired ratio for that complex oxide is achieved in the solution. As soluble Salts are usually the nitrates, chlorides and acetates. Then you give to the Dissolving progressively an alkaline substance such as ammonia or sodium bicarbonate in aqueous solution added. In this way, the formation of a solid precipitate is brought about, which after the pyrolysis finally becomes usable according to the invention complex oxides

Excellent results are obtained with complex oxides of aluminum and magnesium with an internal porosity above 1 cm ³ / g, which correspond to the general formula MgO · Al2O3.

All of the above-described porous oxides can advantageously be subjected to a halogenation treatment prior to the deposition of the magnesium halogen compound under the particular conditions described in the laid-out documents of Belgian patent 7 73 227. This halogenation treatment improves the productivity of the catalysts made from the porous oxides. It consists in subjecting the porous aluminum oxides to the action of a halogenating agent. The latter is preferably a fluorinating agent. Preferably one chooses it from solid and without residue ^; n volatile products from decomposable compounds, such as B. ammonium fluoride. This treatment can be carried out so that the halogenated aluminum oxides or aluminum oxide complexes obtained have a halogen / aluminum atomic ratio between 0.01 and 1. The best results are obtained when this ratio is between 0.06 and 0.30 and in particular between 0.10 and 0.15.

The porous aluminum oxides can prior to being brought into contact with the magnesium compound are advantageously subjected to a thermal treatment, especially when their manufacture has not been completed by pyrolysis. Such treatment is carried out at a temperature carried out between 100 and 1000 ° C, preferably between 300 and 800 ° C. In the case of porous oxides,

which are subjected to halogenation treatment such a thermal treatment can be combined with the halogenation treatment or follow it. It is therefore carried out under such conditions that porous oxides are obtained obtained, which have the previously specified halogen / aluminum atomic ratio. The pressure under which such treatment is carried out and the atmosphere in which one works are not critical. However, for the sake of simplicity, it is preferred to operate under atmospheric pressure and in an inert atmosphere. The duration of the thermal Treatment is also not critical and is generally between 1 and 24 hours.

The above-described porous aluminas must be treated with the magnesium compound in this way that a deposit of this compound is produced on the surface of the porous oxide.

As magnesium alkoxides, for. B. the methylate, the Ethylate, and the isopropylate usable.

Among the magnesium halides can be mentioned will:

- Commercially available magnesium halides, which commonly referred to as "anhydrous" but which are actually hydrated dihalides containing one mole or less of water per Contain molecule of dihalide; »Anhydrous, commercially available« magnesium dichlorides are a typical example of such compounds;

- hydrated magnesium dihalides, which one more contain as one molecule of water per molecule of the dihalide, e.g. B.

MgCl ₂ · _{6H 2} O, MgCl _{2 · 4H 2} O and MgCl ₂ · _{2H 2} O.

Of these, the dihalides are preferred, the best results can be obtained with the hydrated magnesium dichlorides. The use of two or several different compounds from the compounds given above is also in the Scope of the invention.

The amount of magnesium compound to be deposited on the porous alumina is an essential feature of the invention. Expressed in the weight of the magnesium, based on the surface of the porous oxide, it must be between 1 · 10 ^-3 and 5 · 10 ^-3 mg-atom of this metal per m ² specific surface (BET) of the porous oxide.

The results are within those given above Limit values optimal. However, it was observed that the optimum amount of the magnesium compound varies slightly depending on the kind of the compound

The best results are obtained with porous oxides, which have a specific surface area between 200 and 400m ² / g and on which have been deposited:

- 1 x Ο- £ ³ to 5 - 10- ³ mg-atoms Mg / m ² of the specific surface of a Magneshimphenoxids or alkoxide

- 2 - ΙΟ- ³ to 4 - ΙΟ- ³ mg atoms Mg / m ² on the specific surface of a magnesium halide.

The deposition of the magnesium compound on the surface of the porous alumina can occur after any known method. In particular, the required amount of

Magnesium compound deposited on the porous oxide:

- in the form of solids, e.g. B. in suspension in an inert diluent;

- in the form of steam or gas;

- in a liquid medium, be it in the form of a solution in water or in an organic solvent, which is able to dissolve the magnesium compound, be it in the presence of an oxygen-containing organic compound (M), as in the the following is defined in more detail.

The temperature at which the magnesium compound is deposited on the porous aluminum oxide is carried out is not critical. Preferred is carried out at a temperature below the decomposition temperature of the magnesium compound. in the If the magnesium compound is used in the form of a solution, one usually works in the vicinity of the Temperature which corresponds to the maximum solubility of the magnesium compound. The pressure is also not essential; generally one works in close to atmospheric pressure. It is preferred to use the magnesium compound in use liquid medium. It has surprisingly been found that when the Magnesium compound on the porous oxide after this method always part of this compound chemically in an irreversible manner on the porous Alumina remains bound This binding is practically quantitative, if the amount used of the magnesium compound, expressed by weight of this metal, less than 5 - 10- ³ mg-atom of Mg / m ² of specific surface area of the porous oxide is,

The magnesium compound can be used in a liquid medium by several methods, further details are described below. A first way of working is to use the Magnesi reconnection in the form of a solution in a solution To use agent, the water or an organic diluent capable of dissolving the magnesium compound is all common in the organic Chemistry applied diluents can be be turned. However, the alkanes are preferred and cycloalkanes whose molecule contains 4 to 20 carbon atoms, e.g. isobutane, n-pentane, Pentamethylpentane, η-hexane, n-heptane, cyclohexane, methylcyclohexane and the dodecanes. Also can

so you use alcohols whose molecule has 1 to 12 carbon atoms per hydroxyl radical such as Methanol, ethanol, butanol, decanol and cyclohexanol, likewise mixtures of the aforementioned alcohols, alkanes and cycloalkanes.

It is also possible to use solvents which have a strong ability to form complexes, such as B. tetrahydrofuran. Use in the form of an aqueous solution is preferred for the magnesium dihalides

A particularly simple way of causing the deposition of the magnesium compound on the porous alumina according to this procedure consists in the oxide with the help of a volume the solution to treat so that the mixture the Properties of a powder retains this Volume contains an amount of magnesium compound which is at least equal to the amount that is chemically based on the oxide can be fixed or bound that the

Contact preferably at ambient temperature and with stirring for a period of time which generally varies between about 1 minute and 1 hour. The possibly Any excess present can be removed with the aid of a solvent for the magnesium compound. As such. Solvent, a solvent is preferably selected that corresponds to that for carrying out the impregnation or soaking of the porous alumina solvent used is identical.

After the magnesium compound has been deposited on the porous alumina by this procedure the solid thus obtained is generally subjected to an activation treatment, whereby the Removal of the solvent is easily possible. Such activation treatment is general essential if the solvent used was water.

It is preferably carried out at a temperature below the decomposition temperature of the magnesium compound, but this condition is by no means essential, and decomposition of the magnesium compound is harmless to the properties of the catalyst as long as the magnesium content of the porous Oxides remains within the limits given above. The other operating conditions of the activation treatments will depend on the Type of solvent used, and they are generally the same as those used Performs thermal treatment described above.

For certain insoluble in water or one of the above-mentioned organic diluents Magnesium compounds, it is also possible to use them in a liquid medium in accordance with a second mode of operation, in which they are mixed with an oxygen-containing, organic compound (M) of a metal Groups Ia, Hb, IHb, IVa, IVb, Va, Via, VIIa and VIII des Periodic table, optionally in the presence of a diluent, are mixed. Under this Definition of an oxygen-containing, organic compound (M) are to be understood as meaning all compounds in which an organic residue bound to the metal via oxygen is compounds that also binds Contain metal-oxygen as well as condensed compounds, which have bond sequences metal-oxygen-metal, can also be used, provided they also have at least one metal-oxygen-organic residue bond sequence per molecule a

The organic radicals bonded to the metal via the oxygen can be any radicals. They are preferably selected from the same radicals that were used in the composition of the oxygen-containing, organic magnesium compounds are possible, and preferably from hydrocarbon residues and particularly preferably from straight lines or branched alkyl radicals, cycloalkyl radicals, arylalkyl radicals, aryl radicals and alkylaryl radicals.

Ak metals of the groups mentioned above can z. B. are mentioned: lithium, sodium, potassium, zinc, Boron, aluminum, silicon, tin, titanium, zirconium, Vanadium, chromium, manganese, iron, cobalt and nickel, however, the use of oxygen-containing organic compounds of aluminum, silicon, Titanium, Zirconium, Vanadium and Chromium preferred The best results are obtained with oxygenated, obtained organic titanium compounds.

These oxygen-containing organic compounds (M) can be represented by the general formula

[MeOi (OR) J _n ,

are reproduced, in which (Me) is a metal from the above-mentioned groups, R is an organic radical as defined above, χ and / any numbers of x> 0 and y> 0, which are compatible with the valence of the metal (Me), and m are an integer. the

ίο Use of oxygen-containing, organic compounds (M), in which χ 0 < χ < 1 and m 1 < m <6, is preferred. As oxygen-containing organic compounds (M), which are intended to be brought into contact with the magnesium compound, can to be named:

- Alkoxides such as Li (OiC ₃ H ₇ ), Al (OiC ₃ Hr) ₃ , B (OiC ₃ H ₇ ) S, Si (OC ₂ Hs) ₄ , Ti (OiC ₃ H ₇ ) 4, Ti (OiC ₄ Hs ) ₄ , V (OiC ₃ Hr) ₄ and ZrfOiQH ^;

- phenoxides such as Ti (OC ₆ Hs) ₄ ;

- Oxyalkoxides such as VO (OiC ₃ H ₇ J ₃ ;

- condensed alkoxides such as Ti ₂ O (OiC ₃ H ₇ ) O;

- enolates such as titanium acetylacetonate

The use of oxygen-containing, organic compounds (M) which contain several different organic radicals is also possible. The same is true for the use of several different, oxygen-containing, organic compounds one and of the same metal and the use of several oxygen-containing, organic compounds of different metals.

The working conditions for the mixture of the magnesium compound with the oxygen-containing, orga niche connection (M) must depend on the physical state of each of these compounds can be selected such that a liquid Mixture or solution is formed, the / whose magnesium concentration is sufficient to achieve the desired Amount of magnesium to deposit on the surface of the porous alumina. When working in the absence of a diluent, the temperature and pressure conditions are chosen so that at least one of the compounds and preferably the oxygen-containing organic compound (M) is liquid Often such a compound, which is kept in the liquid state, can dissolve the magnesium compound. You can also use a second Use oxygen-containing organic compound (M) the one which is liquid and the magnesium compound able to dissolve.

However, it can happen that the oxygen-containing, organic compound (M) is heated up decomposed that the mixture of this compound and the Magnesium compound becomes solid by cooling or that none of these compounds are in the liquid State can set. In this case you can however, the deposition of the magnesium compound on the porous oxide in liquid medium takes place Use a diluent to accomplish, which is preferably from the aforementioned, organic diluents is selected and for at least partial dissolution of the oxygen-containing organic compound (M) or the product is capable of mixing with the magnesium compound

The use of such a diluent for this purpose is the preferred embodiment

the use of the magnesium compound according to this second procedure. It should be pointed out that this second procedure, and in particular the variant described above, can be applied quite generally to the majority of the water-soluble magnesium compounds and in particular to the dihalides of this metal. It has the essential advantage that in this case the level of activation mentioned in the description of the first mode of operation is suppressed. In preparing the deposit of the magnesium compound on the surface of the porous alumina according to this second embodiment or procedure, the amount of oxygen-containing organic compound (M), which is liquid or dissolved in the diluent, must at least ensure the dissolution of the required amount Magnesium compound is sufficient. In general, the respective amounts of these compounds to be used are such that the atomic ratio between the metal (Me) of the oxygen-containing organic compound and the magnesium is between 0.5 and 100 at-g / at-g and preferably between 0.5 and 2 at-g / at-g varies When using the variant of this second procedure, which consists in adding a diluent to the oxygen-containing organic compound (M) or to the mixture of this compound with the magnesium compound, it is preferred if the total concentration of the dissolved compound or the dissolved compounds is above 5% by weight and preferably above 20% by weight, based on the diluent. The other conditions for preparing the solution or the liquid mixture are not critical. For reasons of simplicity, working between 20 and 300 ^° C. and preferably between 50 and 200 ^° C. and at approximately atmospheric pressure is preferred. The liquid mixture or the solution can be homogenized by stirring.

A very simple way of depositing the magnesium compound on the porous alumina to arrive according to this second embodiment is to first find a solution to the Mixture of magnesium compound and oxygen-containing organic compound (M) in the diluent to produce and the porous oxide with a fixed volume of this solution after the Description of the first embodiment mentioned method to deal with. You can also use the porous The oxide is suspended in this solution, the contact between the oxide and the solution under the Maintaining the above-mentioned conditions, the excess of the solution e.g. by filtration or Remove decanting and recover the solid obtained in this way, which then as such in the continuation of the Preparation of the catalyst complexes (b) is used.

As one of the essential characteristics of the porous aluminum oxides, which are used for the production of the catalyst complexes (b) If their surface content is magnesium, the chemical must be used Reactions, the mechanism of which is not yet known, are not taken into account, which between the Magnesium compound and the oxygen-containing organic compound (M) in the preparation of the molten mixture or the solution, with the aid of which the deposition of the magnesium compound occurs on the porous oxide.

The last step in the preparation of the solid catalyst complexes (b) consists in the porous alumina, on which the magnesium compound is deposited - which is hereinafter referred to as "solid" is referred to -, with one of the mentioned compounds of titanium, zirconium, vanadium or chromium to implement. When the solid is produced with the help of an oxygen-containing organic compound (M) whose metal (Me) is one of these metals,

ίο a transition metal compound is preferably selected, the metal of which is identical to the metal (Me). The best results are obtained with titanium compounds.
When using halogenated compounds, the use of brominated and chlorinated compounds is like

TiCl ₄ , TiBr ₄ , VCl ₄ , VOCl ₃ , VOBr ₃ ,
CrO ₂ Cl ₂ , Ti (OC ₂ Hs) ₃ Cl, Ti (OiC ₃ H ₇ J ₃ Cl,
Ti (OC ₂ Hs) ₂ Cl ₂ , Ti (OiC ₃ H ₇ ) Cl ₃ and ZrOCl ₂

When using compounds containing alkoxide radicals, these are preferably selected from compounds whose straight-chain or branched alkoxide radicals each have 1 to 20 carbon atoms and particularly preferably 1 to 10 carbon atoms each, such as Ti (OiC ₃ H ₇ ) ₃ CL

The use of several different transition metal compounds is also possible.
The transition metal compound is preferably selected such that it is used in the form of vapor or gas, optionally diluted with an inert gas, in liquid form or in the form of a solution. The solvents used are generally the diluents customarily used in the low-pressure polymerization of olefins. However, it is preferred to bring the solid directly into contact with a large amount of the pure transition metal compound kept in a liquid state, for example by simply putting it in suspension.

The reaction can also be brought about by mixing the solid with the transition metal compound, if this is liquid under the reaction conditions, it washes, or by washing the solid with successive, fresh batches of the transition metal compound in a continuously operating extraction apparatus from Soxhlet-oejer Kumayawa-Ty? in Contact is brought. This latter working technique is particularly recommended when the Solid according to the preferred variant of the above

so described, second embodiment or mode of operation has been made

The temperature at which the reaction is carried out is not critical. In general, work is carried out between 0 and 30O ⁰ C. When working at atmospheric pressure, the temperature is selected between the ambient temperature and the normal boiling temperature of the transition metal compound. Therefore, work is preferably carried out between 20 and 140 ° C.
Contact with the transition metal compound is maintained for a sufficient period of time for the transition metal compound to be chemically bonded or fixed to the solid. In general, such a bond or fixation is achieved after 30 minutes to 1 hour

After the reaction, the catalyst complex obtained can (b) Washed with the same transition metal compound that was used for the reaction

became. In general, it is then washed with the aid of an inert hydrocarbon solvent, such as B. isobutane, n-pentane, η-hexane, cyclohexane and the dodecanes, to the chemically not on the Remove carrier-fixed excess of transition metal compound. When performing the elemental analysis of the catalyst complex (b) treated in this way, a transition metal content is measured which is in the is generally above 10 g / kg and very often above 15 g / kg and has a magnesium content, which is equal to or slightly below the magnesium content of the solid that was used to prepare the catalyst complex (b).

The catalytic systems according to the invention further comprise an organometallic compound Metal of groups Ia, Ha, Hb, IHb and IVb des Periodic table such as organometallic compounds of lithium, magnesium, zinc, aluminum or tin. The best results are obtained with organoaluminum compounds.

As aluminum trialkyls whose alkyl chains contain 1 to 20 carbon atoms and are straight-chain or are branched, trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tri-n-butyl aluminum and tri-n-decylaluminum can be used. The use of trialkylaluminum compounds, their Alkyl chains contain 1 to 10 carbon atoms and are straight-chain or branched is preferred

It is also possible to use alkylaluminum hydrides whose alkyl radicals also have 1 to 20 carbon atoms such as diisobutyl aluminum hydride. Also suitable are aluminum alkyl halides in which the Alkyl radicals also contain 1 to 20 carbon atoms, such as ethyl aluminum sesquichloride, diethyl aluminum chloride and diisobutyl aluminum chloride.

Finally, one can also use organoaluminum compounds obtained by that trialkylaluminum compounds or dialkylaluminum hydrides whose radicals have 1 to 20 carbon atoms have been allowed to react with isoprene ("isoprenylaluminum compounds").

As comonomers are propylene, butene- (l), 4-methylpentene- (l) and witch- (l) useful.

The process according to the invention is particularly good for the production of ethylene homopolymers and copolymers which contain at least 90 mol% and preferably 95 mol% ethylene are suitable

The polymerization can be carried out in solution or in suspension by any known technique carried out in a hydrocarbon solvent or diluent or in the gas phase will. Solvents or solvents are used in the solution or in suspension procedures Diluents analogous to those used to wash the catalyst complex (b): these are preferably alkanes or cycloalkanes such as butane, pentane, hexane, heptane, cyclohexane, methylcyclohexane or their mixtures. You can also use the Polymerization in the monomer or one of the Monomers that are kept in the liquid state, carry out.

The polymerization pressure is generally between atmospheric pressure and 100 kg / cm ² , preferably 50 kg / cm ² . The temperature is generally chosen between 20 and 200 ° C. and preferably between 60 and 120 ° C. The polymerization can be carried out continuously or batchwise.

The organoaluminum compound (a) and the catalyst complex (b) can separately to the Polymerization medium are added. They can also be kept at a temperature between -40 and 80 ° C before introducing them into the polymerization reaction vessel Furthermore, bring in contact for a period of time which can range up to 2 hours they can be brought into contact with one another in several stages, or part of the organoaluminum

ίο Add compound (a) before the reaction or else add several different organoaluminum compounds (a).

The total amount of the organoaluminum compound (a) used is not critical. It is generally between 0.02 and 50 mmol / dm ³ of solvent, diluent or volume of the reaction vessel, and preferably between 0.2 and 5 mmol / dm ³ . The amount of catalyst complex (b) used is determined as a function of the transition metal content of the complex. In general, it is selected such that the concentration is between 0.001 and 2.5 and preferably between 0.01 and 0.25 mat-g of the metal per dm ^{3 of} the solvent, diluent or the volume of the reaction vessel

The ratio of the amounts of organoaluminum compound (a) and catalyst complex (b) is also not critical. In general, it is selected so that the ratio of organoaluminum compound /

Transition metal, expressed in moles / g-atom, above of 1 and preferably above 10

The average molecular weight and in particular the melt index of the process according to the invention Polymers produced is by adding hydrogen and optionally one or more other molecular weight regulators, such as zinc or cadmium diethyl, alcohols or carbon dioxide, to the Polymerization medium regulated

The specific weight of the according to the invention Process produced homopolymers can also by adding an alkoxide Metal of groups IVa and Va of the periodic table to the polymerization medium are regulated in this way it is possible to produce polyethylene with specific weights between those of the after a high-pressure process produced polyethylenes and those of classic polyethylenes higher Density lie.

Among those especially for such a scheme

Suitable alkoxides are those of titanium and vanadium, each of which has 1 to 20 carbon atoms contain, particularly effective. These include:

Ti (OCH ₃ K Ti (OC ₂ Hs) ₄ , Ti [OCH2CH (CH3) 2] 4,
TXOCHVdTXOC)

The inventive method enables the production of ethylene polymers with productivities which are comparable or also very often superior to those with previously known catalysts were achieved in which the transition metal compound is based on an activated alumina or halogenate alumina is fixed so exceeds the productivity, expressed in grams of polyethylene per gram of the catalyst complex (b), during homopolymerization of ethylene regularly 1000 and it can even exceed 2000 in the case of catalyst complexes that made of porous oxides that have a

have received prior upgrading treatment. There also the transition metal content of the catalyst complexes (b) is very tight, the concentration is on disruptive catalyst residues when using the polymers are negligible. Therefore, the Polymers cannot be further purified. This way it becomes the most difficult to perform and most costly work process for the final preparation of the polymers avoided.

In addition, the catalyst complexes (b) used according to the invention have a number of completely surprising properties on:

First of all, they enable the production of polymers with melt indices, measured below normal load according to the ASTM D1238-57 T standard, with - compared to the state of the art - a lot less high concentrations of hydrogen as a regulator or modifier, which is particularly advantageous is, since so the hydrogenation of the monomer or monomers to be polymerized is reduced, what the yield of the process is improved

Furthermore, they enable the production of polymers with a factor U _m which is very much higher than that of polymers obtained in the presence of known catalysts.

The factor U _w is calculated using the following formula:

30th

- M _{w is} the weight average molecular weight, defined by the ratio

35

ΣΝ, Μ,

is where M is the number of molecules with one Molecular weight M / represents;

Afζ is the mean molecular weight "z" defined by the ratio

M ₁ =

Σ N ₁ JW?

where M and M, - the meaning given above own.

The ratio of M _x ZMW is by gel permeation chromatography of a solution of 1 g / kg of the values of the fractionation of the polymer in 1,2,4-trichlorobenzene at 130 ⁰ C determined

Table I.

A high factor U _w is representative of a broad molecular weight distribution in the zone of very high molecular weights.

It is therefore possible with the catalysts of the invention, under particularly advantageous polymerization conditions, to prepare polymers with very low melt indices and a very high factor U _{m as defined above.} The combination of these properties enables the production of polymers which are particularly easy to use in shaping processing methods by extrusion or blow molding.In particular, the deformed objects have no surface defects and the phenomenon of deformation cracking, usually referred to as "melt cracking", does not occur even at very high extrusion speeds .

Examples 1 to 8
and comparative experiment A

A - Preparation of the catalyst complexes

An alumina monohydrate of the α-type (boehmite) is kept under a nitrogen atmosphere for 5 hours at 700 ° C. An activated alumina is obtained whose pore volume is 1.1 cm ³ / g and whose specific surface area is 360 mVg.

Fixed amounts of this activated alumina are treated at ambient temperature (25 ° C) with fixed volumes of aqueous solutions of increasing concentrations of hydrated magnesium chloride.The hydrated magnesium chloride used is a commercially available product that _{corresponds to the formula MgCb · 4H 2} O. The treatment is carried out in this way that the reaction mixture retains its powdery properties. The solids obtained are then kept under a nitrogen atmosphere ^{at 250 ° C. for 16 hours.} Then 5 g of each of the solids obtained are ^{suspended in 25 cm 3 of} TiCU, and the mixture is brought to 120 ° C. for 30 minutes with vigorous stirring. The solid reaction product is separated off and washed with hexane until the chlorine ions disappear in The washing liquid is then dried under a stream of dry nitrogen. The special conditions of each of these preparations, the analyzes of each catalyst complex and the magnesium content of each solid are summarized in Table I. used.

example 1

Used amount of activated
Aluminum oxide (g)

Applied volume of the solution of

MgCl ₂ -4 H ₂ O (ml)

Concentration of the MgCl ₂ 4H ₂ O solution (g / l)

Amount of magnesium used

(g / kg of aluminum oxide)

Mg content of the solid obtained
(mg atoms / m ² ) *)

14th 13th 14th 12th 12th 28 26th 28 24 24 36 54 72 90 108 10 15th 20th 25th 30th MO " ³ 1.6 x 10 ^-3 2-HT ³ 3 · 10 ' ³ 3.3

continuation

example

Ti content of the catalyst complex (mg / g) 18 18 18 19 18

a-Content of the catalyst complex (mg / g) 80 89 96 101 111

Mg content of the catalyst complex (mg / g) 8.7 14 17 25 28

Table I (continued)

Example 6 Comparative Experiment A

Amount of activated aluminum oxide used (g)

Applied volume of solution 40 of MgCl ₂ -4H ₂ O (ml)

Concentration of the MgCl ₂ · 4 H ₂ O solution (g / l) 126

Amount of magnesium used 35 (g / kg of aluminum oxide)

Mg content of the solid obtained 3.3

(mg atoms / m ² ) *)

Ti content of the catalyst complex (mg / g) 22

Cl content of the catalyst complex (mg / g) 123

Mg content of the catalyst complex (mg / g) 28

20th 40

144
40

3.5 · 10

22nd

130

30th

-3

25th
50

180
50

4.4 10

149

1-3

17th
78

*) Content, expressed per m ^{2 of} the specific surface of the aluminum oxide before the treatment at 250 ^° C.

Interestingly, it is the fixation or binding of the magnesium on the surface of the aluminum oxide practically quantitative, taking into account the amount of magnesium used.

B - Polymerization experiments

Two series of polymerization experiments were carried out with the catalyst complexes described above carried out under the following common conditions:

A certain amount (see Tables II and III) of the catalyst complex in 500 ml of hexane in 45 a 1500 ml stainless steel autoclave equipped with a paddle stirrer in suspension convicted. 100 mg of triisobutylaluminum were added to this. The temperature rose to 85 ° C brought and introduced ethylene and hydrogen under the partial pressures given below. the

Table II *)

The polymerization was carried out for 1 hour while maintaining a constant ethylene pressure continuous addition of ethylene carried out. After blowing off the autoclave, the values in the tables II and III specified amounts of polyethylene obtained.

The first series of polymerization experiments (Examples 1 to 8 and Comparative Experiment A) was carried out under identical partial pressures of ethylene and hydrogen carried out. The results of these trials are compiled in Table II.

The second series of polymerization experiments (Examples 9-16 and Comparative Experiment B) was carried out with same series of catalyst complexes under different partial pressures of ethylene and hydrogen carried out, the ratio of these partial pressures was selected within the limits that one Polymer obtained whose melt index was between about 0.15 and about 0.20. The results of this Experiments are listed in Table III.

Catalyst complex prepared in example
12 3 4 5 6

Comparative experiment A

Weight of the used
Complex (mg)

Weight gained
Polyethylene (PÄ), (g)

Catalytic productivity
(g PA / g catalyst complex)

Specific activity

(g PÄ / hXgTiXkg / cm ² C ₂ H ₄ )

Melt index (MI)
(g / 10 min) ***)

150 125 125 100 75 50 41 37 75

78 89 89 97 63 70 70 78 51

500 700 700 950 850 1400 1700 2100 680

2900 3900 3900 5100 4600 6400 7700 10 GOO 3990

* ♦) **) **) Q _{04 Oj06 0) 26} o, 28 0.53 **)

continuation

Catalyst complex prepared in Example 1 2 3 4

COMPARISON A

Melt index below a strong 0.27 2.14 3.2 4.36 5.44 15.95 13.67 23.2 Load (HLMT) (g / 10 min) ****) Ratio HLMI / MI - - - 109 91 61 49 44

*) Partial pressures of ethylene (10 kg / cm ² ) and hydrogen (4 kg / cm ² ), which were the same in all tests. **) Not measurable.

***) Measured under normal load, 2.16kg according to the ASTM 1238-57T standard. ****) Measured under heavy load, 21.6 kg according to ASTM 1238-57 T.

0.65

Table II clearly shows that the specific Activity and the catalytic productivity of the catalysts used according to the invention below identical polymerization conditions are better than those of catalysts of the prior art based on activated aluminum oxide (comparative experiment A was carried out with a catalyst complex carried out, which was prepared in the same manner as the catalyst complexes of Examples 1-8

Table ΙΠ

was, however, without treating the activated aluminum oxide with magnesium chloride) as soon as the magnesium content of the solid ^{exceeds 2 · 10 -3} mg atom / m ² on specific surface the magnesium content of the catalyst complexes increased.

example 10 11 12th 13th 2 3 4th 5 14th 15th 16 Comparison 9 Catalyst complex, prepared according to the example 159 157 105 108 attempt B 1 6th 7th 8th Comparison 250 10 10 10 10 50 39 36 attempt A Weight of the used 210 Catalyst complex (mg) 8th 10 10 S. 5 10 10 10 Partial pressure of ethylene 8th (kg / cm ² ) (1) 15th 1 1 0.8 0.5 3 3 2 Partial pressure of hydrogen 88 83 110 111 IS (kg / cm ² ) (2) 1.9 0.3 0.3 0.2 Ratio (2) / (l) 67 550 550 700 1000 94 78 98 1.9 Weight of the gained 96 Polyethylene (g) 270 0.15 0.20 0.18 0.20 1900 2000 2700 Catalytic productivity 14.42 18.67 16.27 12.01 720 (g PA / g catalyst complex) 0.10 0.28 0.25 0.14 Melt index (g / 10 min) (3) 9.02 96 94 90 60 10.93 9.28 8.22 0.17 Melt index under strong 13th 21 28 26th 14.8 Load (g / 10 min) (4) 90 61 62 59 Ratio (4) / (3) 15th 16 11 13th 87 Factor U _w 11

The experiments compiled in Table III show that, according to the invention, the production of Polyethylene is possible melt indices, which are in the same order of magnitude as the melt indices of polyethylenes produced with the aid of catalysts of the prior art, but with a lot less molecular weight regulator (hydrogen) is used and the catalytic Productivity is increased.

The F i g. 1 of the drawing shows that the catalyst complexes obtained from solids, the magnesium content of which varies ^{from about 1 · 10 -3 to 5 · ΙΟ -3} mg / atoms / m ² on specific surface, the lowering of the ratio of the partial pressures of hydrogen and Enable ethylene by a factor of about 10, with polyethylenes with comparable melting indices being obtained. Also show the Examples 9 to 16 and FIGS. 2 of the drawing that with the same change in the magnesium content, the U _w factor of the polyethylene obtained is always higher than the U _w factor of polyethylene, which was obtained in the presence of the catalyst complex according to Comparative Experiment A, and that an optimum for the magnesium content of the solids is present , which corresponds to a maximum of the values for the factor U _n.

Examples 17 and 18 and comparative experiment C

A - Preparation of the catalyst complexes

Mix aluminum oxide monohydrate of the -type (boehmite) with about 4% by weight of NH4F Mixture to a temperature of 700 ° C and maintains this

Temperature for 1 hour The upright so .erhaltene fluorinated alumina is subjected to a thermal treatment which is carried out at 700 ⁰ C for 5 hours under a nitrogen atmosphere. Its specific surface is 250 mVg and its pore volume is 1 cm ³ / g.

Fixed amounts of this fluorinated alumina are treated with aqueous solutions of MgCl ₂ · 4 H2O in the same way as for the preparation of the catalyst complexes of Examples 1 to 8. The solids obtained are then kept for 16 hours at 250 ° C under a nitrogen atmosphere. Finally, they are treated with TiCl in the same manner as in Examples 1 to 8 except that the treatment temperature is 130 ⁰ C and the reaction product is subjected to five extractions with boiling TiCl.

Table IV

B - Polymerization experiments
The washed and dried products are used as catalyst complexes in polymerization experiments which were carried out under the same conditions that are detailed in paragraph B of Examples 1 to 8. The particular conditions for the preparation of these catalyst complexes, the results of their analysis, the particular conditions and results of the polymerization and the properties of the polyethylenes obtained are summarized in Table IV, which also shows the results obtained with a comparative complex which is described in in the same way as the catalyst complexes described above, but omitting the treatment step of the fluorinated aluminum oxide with magnesium chloride (Comparative Experiment C).

Special conditions Example 17 Example 18

Comparative experiment C

Amount of magnesium used (g Mg / kg fluorinated aluminum oxide) Mg content (mg atoms of the solid obtained / m ² ) (before the treatment at 250 ° C.

Ti content of the catalyst complex (mg / g) F content of the catalyst complex (mg / g) Cl content of the catalyst complex (mg / g) Mg content of the catalyst complex (mg / g) Weight of the catalyst complex used (mg) Amount of used Triisobutylaluminum (mg) partial pressure of ethylene (1) (kg / cm ² ) partial pressure of hydrogen (2) (kg / cm ² ) ratio (2) / (l)

Weight of polyethylene recovered (PÄ) (g) Catalytic productivity (g PÄ / g catalyst complex) Melt index (g / 10 min) (3)

Melt index under heavy load (g / 10 min) (4) Ratio (4) / (3)

Factor U _w

From Table IV it can again be seen that there is an optimum for the magnesium content of the solids with the aid of which the catalyst complexes are prepared according to the process of the invention, which corresponds to a maximum of the catalytic productivity and the production of a polyethylene at a much lower ratio of Partial pressures of hydrogen and ethylene made possible, which has a comparable melt index and a higher factor U _w compared to polyethylene, which was obtained in the presence of the comparative catalytic complex according to comparative experiment C.

Example 19

A complex oxide of the general formula MgO ■ Al2O3 (spinel) was subjected to a study carried out under a stream of dry nitrogen at 900 ⁰ C for 5 hours thermal treatment. A complex oxide was obtained which was distinguished by a specific surface area of 290 m ² / g and an internal porosity of 1.5 cm ³ / g. This

15th 25th - 2.3 10 " ³ 3.7 ΙΟ- ³ - 13th 14th 7.7 23 22nd 35 61 87 24 14th 23 -. 107 51 140 100 100 200 10 10 8th 10 5 15th 1 0.5 1.9 80 99 103 750 2000 736 0.10 0.11 0.23 7.98 10.15 11.5 80 92 50 12th 13th 10

complex oxide was made with an aqueous solution of MgCb · 4 H2O in the same manner as in the Examples 1 to 8 treated, the amount of magnesium used being 15 g of magnesium / kg of complex oxide was the same. The magnesium content of the solid obtained, which is only a fixation of the Magnesium chloride is, therefore, betmg 4.6 · ΙΟ- ³ mg atoms Mg / m ² on a specific surface. After an activation treatment carried out at 250 ° C. for 16 hours and after the reaction with TiCU, which was carried out as indicated in Examples 2 to 8, the catalyst obtained contains complex per g 19 mg titanium and 111 mg chlorine. One carried out with 41 mg of this complex under the same conditions specified in paragraph B of Examples 1 to 8 and under partial pressures of ethylene and hydrogen of 10 and 2 kg / cm ^2, respectively The polymerization test yielded 68 g of polyethylene, its melt index 0.16 g / 10 min and its melt index under heavy load was 8.07 g / 10 min. The catalytic productivity was 1650 g PA / g catalytic

torkomplex, and the specific activity 8700 g PA / h g Ti χ kg / cm ² C ₂ IU- The factor U _{w of} the polyethylene was 6.

Comparative experiment D

For comparison, it should be stated that under the conditions given in Example 19 with 60 mg of a catalyst complex, which was prepared in the same way, but without treatment of the complex oxide with a magnesium halogen compound (Τι content = 13 mg / g), ι ο was, the polymerization test carried out made it possible to obtain 25 g of polyethylene with an immeasurable melt index and a melt index under heavy load of 0.61 g / 10 min. The catalytic activity and the specific activity are 420 g PA / g catalyst complex and 3200 g PA / h χ g Ti kg / cm ² C ₂ H ₄ .

Example 20

20th

For the preparation of the catalyst complex used in this experiment 12.4 g of magnesium ethylate Mg were added (OC ₂ Hs) ₂ to 17 g of titanium tetrabutylate Ti (OC ₄ H ₉ J _4, and the mixture was stirred for 6 hours at 130 ⁰ C envärmt was an almost complete dissolution of the Magnesiumäthylats observed in the mixture was the atomic ratio Ti / Mg O ^ at-g / at-g ± 10% error as a result of impurities, containing the compounds used. prepared to the thus and accommodating at 90 ⁰ C. 60 cm ^{3 of} hexane were added to the cooled mixture, and the whole was stirred at this temperature for 1 hour. The solution thus obtained was brought to a volume of 120 cm ^{3 by adding hexane}

18.5 cm ^{3 of} this solution, ie a volume containing about 0.4 g of magnesium, was gradually introduced into 100 cm ^{3 of} a suspension containing 21 g of a fluorinated alumina prepared according to paragraph A of Examples 17 and 18 that so formed mixture 15 minutes at ambient temperature overnight, then decanting the supernatant liquid was allowed and then removed the analysis showed a content of on the so obtained solid, fixed or bound magnesium of 22 ■ ΙΟ- ³ mat-g / m ² of specific surface area. The solid obtained in this way was first ^{transferred into suspension in 140 cm 3 of} TiCl ₄ with stirring for 2 hours at ambient temperature, then after removal of the first TiCU charge in the same volume of TiCl ₄ for 30 minutes at 120 ° C. Finally, the catalyst complex obtained was separated off, washed with hexane until chlorine ions disappeared in the washing liquid and dried under a stream of dry nitrogen. It contained 18 g of titanium. 21 g fluorine, 65 g chlorine and 14 g magnesium per kg. A polymerization test carried out under the same conditions as the first series of polymerization tests (Examples 1 to 8) with 55 mg of the catalyst complex made it possible to produce 117 g of polyethylene, its melt index 0.14 g / 10 min and its melt index under heavy loads 11.03 g / 10 mm. Their ratio was therefore about 79, and the U _w factor of the polyethylene was 11. The catalytic productivity was 2100 g PA / g catalyst complex and the specific activity 11700 g PA / h g Ti χ kg / cm ² C ₂ H ₄ .

If one compares the results of this experiment with those of the comparative experiment C, it turns out again that it is possible in the presence of the catalyst complexes used according to the invention, a polyethylene with a comparable melt index and a higher factor U _w at a much lower ratio of the partial pressures of hydrogen and To obtain ethylene.

Example 21

To prepare the catalyst complex used in this experiment, the hydrated magnesium chloride used in Examples 1 to 8 was first heated to 185 ° C. until the monohydrate was obtained 6 hours heated with stirring to 13O ⁰ C. Almost complete dissolution of the magnesium chloride was found. The atomic ratio of Ti / Mg 2at-g / at-g in the mixture was ± 10% as a result of impurities contained in the compounds used. ^{300 cm 3 of} hexane were added to the cooled mixture, and the whole was ^{heated to 90 °} C. for 1 hour with stirring. The soluble fraction of the cooled mixture was recovered; it was analyzed to contain 6.5 g Mg / l

20 g of a fluorinated aluminum oxide prepared according to paragraph A of Examples 17 and 18 were suspended in 100 cm ^{3 of} hexane and then ^{treated with 56 cm 3 of} the soluble fraction of the mixture described above 21 was described. The solid obtained contained 2.5 · ³ mg atoms of Mg / m ² on a specific surface. The catalyst complex contained 24 g titanium, 23 g fluorine and 73 g chlorine as well as 11 g magnesium per kg. A polymerization experiment carried out under the same conditions as in Example 21 with 52 mg of the catalyst complex made it possible to produce 69 g of polyethylene with a melt index (1) of 0.18 g / 10 min and a melt index under heavy loads (2) of 10.67 g / 10 min and a factor U _w of 19. The ratio (2) / (l) is therefore approximately equal to 59. The catalytic productivity is 1350 g PA / g catalyst complex and the specific activity is 5600 g PA / h χ g Ti χ kg / cm ² C ₂ H ₄ .

Example 22

12 g of an activated aluminum oxide prepared as in paragraph A of Examples 1 to 8 was ^{treated with 24 cm 3 of} a solution which contained 18 g / l magnesium methylate Mg (OCHs) ₂ in methanol. The treatment was carried out in such a way that the reaction mixture was powdery Typical retained The resulting solid was dried in vacuo at 50 ⁰ C for 1 hour His magnesium content amount 1.1 - ³ ΙΟ- mat-g / m ² of specific surface area. This solid was then _{treated with TiCl 4} , as described in paragraph A of Examples 1 to 8. The catalyst complex obtained contained, according to the analysis, 20 g of titanium, 90 g of chlorine and 9.7 g of magnesium per kg.

One under the general conditions mentioned in paragraph B of Examples 1 to 8, but with 102 mg of the catalyst complex and under partial pressures of ethylene and hydrogen of 10 kg / cm ² and 6 kg / cm ^{2, respectively}

A polymerization test carried out enabled the production of 71 g of polyethylene with a melt index (1) of 0.19 g / 10 min, a melt index under heavy load (2) of 12.65 g / 10 min and a factor U _w of 16. The ratio (2) / (l) is therefore about 67. The catalytic productivity is 700 g PA / g catalyst complex and the specific activity is 3500 g PA / h g Ti χ kg / cm ² C ₂ H ₄ .

Example 23

This example concerns the copolymerization of ethylene with propylene and butene- (l).

A catalyst complex was prepared according to the procedure of Examples 1 to 8A, but using as activated alumina a fluorinated alumina was used, as in Examples 17 and 18, is described.

The catalyst complex obtained in this way contained 17 g of titanium, 81 g of chlorine, 23 g of fluorine and 20 g of magnesium per kg. The content of the obtained solid of magnesium prior to the treatment at 250 ° C was 3.5 χ ^10-3 mg atoms / m ^2.

There were two attempts to copolymerize ethylene with propylene on the one hand and n-butene- (l) on the other hand carried out under the following conditions:

- 1.5 1 stainless steel autoclave,

- diluent: 0.5 1 hexane,

- temperature: E5 ° C,

- Duration: 1 hour,

- Activator: 100 mg triisobutyl aluminum,

- Ethylene partial pressure: 10 kg / cm ² .

The particular conditions for these experiments and the results obtained are given in Table V. compiled:

Table V

Comonomer

Propylene n-butene- (l)

Amount of imported 60 530 10 Comonomers (mmol) Amount of used 76 56 Catalyst complex (mg) Hydrogen partial pressure 4th 2 (kg / cm ² ) 15th Hourly production 67 36 of copolymer (g) Practical activity (g Co- 880 640 polymer / hXg catalyst 20th complex X kg / cm ² C ₂ H ₄ ) Specific activity (g Co- ' 5150 3770 polymer / hXg Ti X kg / cm ² C ₂ H ₄ ) Melt index (MI) of the er 0.50 0.36 25th holding copolymer (g / 10 min) Melt index under strong 29.4 16.62 Load (HLMI) of the er holding copolymer 30th (g / 10 min) HLMI / MI ratio 59 46 Specific weight of the 0.957 0.934 obtained copolymer 35 (kg / dm ³ )

For this purpose 2 sheets of drawings

Claims (1)

Patent claims: 1. Process for the low pressure polymerization of ethylene or for the low pressure copolymerization of Ethylene and olefins with 3 to 6 carbon atoms in the presence of catalysts a) an aluminum trialkyl, alkyl aluminum hydride or alkyl aluminum halide, the alkyl radicals of which are straight-chain or branched and 1 contain up to 20 carbon atoms, or a reaction product of the aluminum trialkyls mentioned or alkyl aluminum hydrides with isoprene and b) a solid catalyst complex, which by reaction of a halide oxyhalide or alkoxyhalide of one of the metals titanium, vanadium, zirconium or chromium with a porous aluminum oxide or a porous _2Q complex oxide of the formula