CS215015B2 - A process for the catalytic production of an ethylene copolymer - Google Patents

Abstract

The invention relates to a process for the catalytic production of an ethylene copolymer using a titanium-containing catalyst at a productivity of > 50,000 kg of polymer per 1 kg of titanium in a reactor at a pressure below 6.87 MPa in the gas phase, the polymer being produced in granular form and having a density of 910 to 940 kg/m3, inclusive, and a melt flow rate ratio of 22 to 32, inclusive. The process is characterized in that ethyl is copolymerized together with at least one C3 to C6 α-olefin at a temperature of 30 to 105 °C by contacting the monomer feed in the presence of 0 to 2.0 moles of hydrogen per mole of ethylene in a gas phase reaction zone with particles of a catalytic system comprising a precursor which is the reaction product of a magnesium halide, a certain titanium compound and an electron donor compound and which is impregnated in a porous support. The precursor is activated with an organoaluminum compound. The polymerization is preferably carried out in a fluidized bed. The copolymers obtained are suitable for the production of films. ;

Description

The invention relates to a method for catalytic production of ethylene copolymer using a titanium-containing catalyst at a productivity of > 50,000 kg of polymer per 1 kg of titanium in a reactor at a pressure below 6.87 MPa in the gas phase, the polymer being produced in granular form and having a density of from 910 to 940 kg/m ³ , inclusive, and a melt flow rate ratio of 22 to 32, inclusive.

The process is characterized in that ethyl is copolymerized together with at least one C3 to C6 α-olefin at a temperature of 30 to 105 °C by contacting the monomer feed in the presence of 0 to 2.0 moles of hydrogen per mole of ethylene in a gas phase reaction zone with particles of a catalytic system containing a precursor which is the reaction product of a magnesium halide, a certain titanium compound and an electron donor compound and which is impregnated in a porous support. The precursor is activated with an organoaluminum compound. The polymerization is preferably carried out in a fluidized bed. The copolymers obtained are suitable for the production of films. ;

The invention relates to a method for the catalytic production of an ethylene copolymer using highly active complex catalysts containing magnesium and titanium by a gas phase process to form ethylene copolymers with a density of from 9.1.0 kg/m ³ inclusive to 940 kg/m ³ inclusive with a melt flow rate ratio (defined below) in the range of from 22 inclusive to 32 inclusive.

Until recently, low-density polyethylene (i.e., with a density of 940 kg/ ^m3 or less) was produced industrially mostly by high-pressure (i.e., 103 MPa or higher) gas-phase homopolymerization of ethylene in stirred and long tube reactors, in the absence of solvents, and using radical initiators. More than 450,000 tons of low-density polyethylene are produced annually worldwide in this manner.

As recently disclosed in U.S. Patent No. 4,011,382 and Belgian Patent No. 839,380, it has been found that low-density polyethylene can be produced industrially at pressures below 6.87 MPa by gas-phase reaction in the absence of solvents using certain catalysts containing chromium and titanium (and optionally fluorine) and under specific operating conditions in a fluidized bed process.

However, the products produced by the processes described in the processes of U.S. Patent No. 4,011,382 and Belgian Patent No. 839,380 have a relatively wide molecular weight distribution Mw/Mn from 6 to 20 (inclusive), and as such, although they are well suited for numerous applications in the field of wire and cable insulation and hose production, they are not very suitable for injection molding. They are also not very widely used for film production, since films made from these resins have poor optical and mechanical properties.

In order to be useful in an industrial gas phase process, such as the fluidized bed process of U.S. Patent Nos. 3,709,853, 4,003,712 and 4,011,382, Canadian Patent No. 991,788 and Belgian Patent No. 839,380, the catalysts must have high activity, i.e., they must have a productivity of at least 50,000 and preferably at least 100,000 kg of polymer per kg of the main metal forming the catalyst, or higher. This is because such gas phase processes typically do not employ any procedures for removing catalyst residues. The catalyst residues in the polymer must therefore be small enough to be retained in the polymer without causing undesirable problems in the production of the resins, in the processing of the resins and/or in the application of the finished products to the end user. Where highly active catalysts are successfully used in such fluidized bed processes, the heavy metal content in the resin is on the order of 20 ppm of the main metal or less at a productivity of at least 50,000 or more, 10 ppm or less at a productivity of at least 100,000 or more, and 3 ppm or less at a productivity of 300,000 or more. Low catalyst residue content is also important where the catalyst contains chlorine-containing substances, such as titanium, magnesium and/or aluminum chlorides used in so-called Ziegler or Ziegler-Natta catalysts. High chlorine content in the molding resin can cause pitting and other corrosion of metal surfaces of molding equipment. Chlorine content of 200 ppm or more is unacceptable for industrial production.

U.S. Patent No. 3,989,881 discloses the use of a highly active catalyst in a slurry process for the production of ethylene polymers having a relatively narrow molecular weight distribution Mw/Mn, in the range of about 2.7 to 3.1. Attempts have been made to use catalysts similar to those described in U.S. Patent No. 3,989,881 in the production of polyethylene with a narrow molecular weight distribution by polymerizing ethylene alone or in conjunction with propylene in the gas phase in a fluidized bed process using equipment and conditions similar to those described in U.S. Patent No. 4,011,382 and Belgian Patent No. 839,380. However, these attempts have been unsuccessful. In order to avoid the use of solvents used in the slurry-type catalytic systems described in U.S. Patent No. 3,989,881, the titanium and magnesium-containing components were dried. However, the dried material was in the form of a viscous, resinous pyrophoric material which could not be easily fed into the reactor because it was not free-flowing. Even when this material was mixed with silica to improve mobility (fluidity) and fed into the reactor in this form, industrially acceptable results were not achieved. The catalyst productivity was low or the catalyst was pyrophoric and difficult to handle or the polymer product had a low bulk density, i.e. less than or equal to 97.3 kg/m ³ .

Polymers with such bulk density are not required from an industrial point of view because of their powdery nature. In case the polymer is to be stored or sold in granular form, a considerably larger space is required for the storage and transportation of such products. Even if the granular polymer is to be processed into pellets before transportation, processing such a large amount of low bulk density material in a pelletizing device requires a considerably longer processing time compared to the time for processing the same amount of high bulk density material in the same extruder.

U.S. Patent No. 4,124,532 discloses the polymerization of ethylene and propylene using highly active catalysts. These catalysts include complexes which may contain magnesium and titanium. The complexes are prepared by reacting a halide of the general formula MX2 (where M may be magnesium) with a compound of the general formula M'Y (where M' may be titanium and Y a halogen or organic radical) in an electron donor compound. These complexes are then isolated either by crystallization, evaporation of the solvent, or precipitation.

The polymerization is carried out using these catalytic complexes and an alkylaluminum compound.

However, U.S. Patent No. 4,124,532 does not disclose any special technique or methods of catalyst preparation to achieve the desired results in the process of the invention described in these references. The use of the catalysts described in U.S. Patent No. 4,124,532 without these special methods would not result in an industrial fluidized bed process suitable for the production of polyethylene on an industrial scale. Furthermore, the gas phase examples do not describe a practical copolymerization process suitable for the production of the special low density copolymers having the preferred morphology of the invention described in these references.

U.S. Patents Nos. 3,922,322 and 4,035,560 describe the use of several catalysts containing titanium and magnesium for the production of granular ethylene polymers by a gas phase fluidized bed process at pressures below 6.87 MPa. However, the use of these catalysts in these processes has significant disadvantages. The use of the catalyst according to U.S. Patent No. 3,922,322 results, as shown in the exemplary embodiment of this patent, in polymers with a very high content of catalyst residues, i.e. a residue of about 100 ppm Ti and more than about 300 ppm Cl. In addition, as shown in the exemplary embodiment of U.S. Patent No. 3,922,322, the catalyst is used in the form of a prepolymer and very large volumes of the catalyst composition must be fed into the reactor. The preparation and use of this catalyst therefore require the use of relatively large equipment for the production, storage and transport of this catalyst.

Also, using the catalysts of U.S. Patent No. 4,035,5610, polymers containing high amounts of catalyst residues are obtained, and the catalyst compositions used are, as is evident from the types and amounts of reducing agents used in these catalysts, pyrophoric.

US Patent Application No. 892,325, filed March 31, 1978 (authors: FJ Karol et al., title: Preparation of Ethylene Copolymers in a Fluidized Bed), states that ethylene copolymers with a density of 910 to 960 kg/m ³ , with a melt flow rate ratio (defined below) of 22 to 32, inclusive, and with a low content of catalyst residues can be produced in granular form at relatively high productivity by polymerizing the monomer or monomers in a gas phase process using a specific highly active complex catalyst containing magnesium and titanium, which is mixed with an inert carrier. The granular polymers thus produced have excellent physical properties that allow their widespread use as molding resins. However, these polymers have several disadvantages. First, because the catalyst contains a carrier that is not removed from the polymer before it is molded, polymers containing some of these carriers are not very suitable for the production of clear films. The carrier particles can impair the properties of clear films made from these polymers. Second, these polymers, especially those polymers that have a lower density, have a relatively low bulk density. Processing these polymers therefore requires the use of larger volumes for transportation and storage than is the case with pelletized products to which the processing industry is accustomed. This leads to the need for greater capital investment in the equipment needed to handle and store these low bulk density granular materials. In addition, the dosing of low bulk density granular materials into molding and extrusion equipment requires a longer dosing time than is the case for dosing the same weight of pelletized material, since a larger volume of granular material must be processed. Third, the polymer particles formed during fluidized bed polymerization have an irregular shape and are somewhat difficult to levitate. The resulting product also contains a relatively high number of dusty particles, i.e. particles with a size of 150 or less.

It has now been unexpectedly found that ethylene copolymers with a wide density range from 910 to 940 kg/ ^m3 and with a melt flow rate ratio of 22 to 32, inclusive, which have a relatively low catalyst residue content and a relatively high bulk density and which provide films with good clarity, can be produced at high productivity, suitable for industrial production, by copolymerizing ethylene with one or more C3 to C6 olefins in the gas phase in the presence of a highly active catalyst comprising a magnesium-titanium complex, as described below, prepared under specific activation conditions with an organoaluminum compound, by impregnating a porous inert* support.

The object of the invention is therefore to develop a method for producing ethylene copolymers with a density of about 910 to about 940 kg/ ^m3 , with a melt flow rate ratio of about 22 to 32 inclusive, with a relatively low content of catalyst residues and a bulk density of 303 to 503 kg/ ^m3 , which would provide films with good properties, by a gas phase process at low pressure with relatively high productivity.

Another object of the invention is to prepare granular ethylene copolymers whose particles have a rounded shape and are more easily suspended in a fluidized bed and which contain a relatively small amount of fine dust-like particles.

The method according to the invention can be used to obtain new

215013 ethylene copolymers suitable for numerous applications.

The attached figure shows a fluidized bed reaction system for a gas phase process in which the catalytic system of the invention can be used.

The process according to the invention can produce copolymers containing ethylene as the main molar fraction (50%) and as a minor molar fraction (g: 10%) one or more C3 to C6 α-olefins, which should not contain any branches on any of their carbon atoms that are closer to the main chain of the copolymers than the fourth carbon atom. In the case of using one C5 to C6 α-olefin, copolymers are obtained, in the case of using more C3 to C6 α-olefins, ter- or tetrapolymers, etc. are obtained. As such α-olefins, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1heptene and 1-octene can be mentioned. Preferred α-olefins are propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene.

The copolymers have a melt flow ratio of from 22 to 32, preferably from 25 to 30, inclusive. The melt flow ratio is another way of characterizing the molecular weight distribution of a polymer. A melt flow ratio (MFR) value of 22 to 32 (inclusive) corresponds to a Mw/Mn value in the range of about 2.7 to 4.1, and an MFR value of 25 to 30 (inclusive) corresponds to a Mw/Mn ratio of about 2.8 to 3.6.

The copolymers have a density of about 910 to 940, preferably 917 to 935 kg/m ³ , inclusive. The density of the copolymers can be controlled, for a given melt flow index, primarily by the amount of Cs to Ce comonomer to be copolymerized with the ethylene. In the absence of comonomer, ethylene would homopolymerize with the catalyst of the invention to form homopolymers with a density of about 0.96. The addition of increasing amounts of comonomer to the polymers results in a gradual decrease in the density of the copolymers. Under the same reaction conditions, the amount of each of the different C3 to C8 comonomers required to achieve the same result varies from monomer to monomer.

To achieve the same results, i.e. the same density at a certain melt flow index, increasing molar amounts of comonomers are required in the series C3 > Cd > C5 > C6 >

> C7 > C8.

The melt flow index of polymers is a reflection of their molecular weight. Polymers with relatively high molecular weight have relatively low melt flow index. Ultra-high molecular weight ethylene polymers have a melt flow index at higher loads (HLMI) of about 0.0 and very high molecular weight polymers have a melt flow index of about 0.0 to about 1.0 g/10 min. Such high molecular weight polymers are difficult to mold in conventional injection molding machines, and sometimes even impossible. The copolymers produced by the process of the invention, on the other hand, are easily molded in such equipment. They have a melt flow index at normal loads (MI) in the range of from 0.0 to about 100, preferably in the range of from about 0.5 to 80, and a melt flow index at higher loads (HLMI) of from about 11 to about 2000. The melt flow index of the polymers produced by the process of the invention is dependent on a combination of the reaction temperature during polymerization, the density of the copolymer, and the hydrogen/monomer ratio in the reaction system. The melt flow index increases with increasing polymerization temperature and/or decreasing polymer density and/or increasing hydrogen/monomer ratio. In addition to hydrogen, other chain transfer agents, such as dialkylzinc compounds, can also be used to further increase the melt flow index of copolymers.

The copolymers produced by the process according to the invention contain á 1 and usually š 0.1 to

0.3 C=C double bonds per 1000 carbon atoms and have a content of n-hexane extractable components (at 50°C) of less than about 3% and preferably less than about 2% by weight.

The copolymers produced by the process according to the invention contain as catalyst residues on the order of 0 to 20 ppm Ti inclusive at a productivity of 50,000* or higher, 0 to 10 ppm Ti inclusive at a productivity of 100,000 or higher and 0 to 3 ppm inclusive at a productivity of 300,000 or higher. As for Cl, Br or I residues, the content of these elements in the copolymers depends on their content in the catalyst precursor. From the value of the ratio of the amount of titanium κ to chlorine, bromine or iodine in the original precursor, the content of chlorine, bromine or iodine residues can be calculated on the basis of the known productivity value, based on the titanium residue itself.

For many copolymers produced using only chlorine-containing catalyst components (Cl/Tl = 7), residual chlorine content can be calculated to range from 0 to 140 ppm inclusive at a productivity of 50,000 or more, from 0 to 70 ppm inclusive at a productivity of 100,000 or more, and from 0 to 20 ppm inclusive at a productivity of 300,000 or more. The copolymers are readily produced at productivity of up to about 500,000 by the process of the invention.

The copolymers produced by the process of the invention are granular materials having a mean particle size on the order of about 0.127 to about 1.78 mm and preferably about 0.5 to about 1 millimeter. The particle size is important for easy fluidization of the polymer particles in a fluidized bed reactor, as discussed below. The copolymers produced by the process of the invention have a bulk density of about 308 to about 503 kg/m ³ .

The copolymers produced by the process according to the invention are suitable not only for film production but also for other shaping applications.

For the production of films, those copolymers according to the invention are preferably used which have a density of about 9.12 to 940, preferably 9.16 to 928 kg/m ³ , inclusive, a molecular weight distribution of 2.7∼Mw/Mn∼3.6, preferably 2.8∼Mw/Mn∼3.1, and a standard melt flow index (MFI) of 0.5∼MFI∼5.0, preferably about 0.7∼MFI∼4.0. The films have a thickness of from 0. to 0.25 mm, preferably up to 0.12 mm and most preferably up to 0.025 mm.

Copolymers produced according to the invention suitable for injection molding into flexible articles, such as household articles, preferably have a density of from 920 to 540, preferably from 925 to 930 kg/ ^m3 , inclusive, a molecular weight distribution range of 2.7 to 3.6, preferably 2.8 to 3.1, and a MFI value of 2 to 100, preferably about 8 to 80.

The compounds used for preparing the highly active catalyst used according to the invention include at least one titanium compound, at least one magnesium compound, at least one electron donor compound, at least one activating compound and at least one porous inert substance as a support.

The titanium compound has a structure corresponding to the general formula

Ti(OR) _and X _b where represents

R Ci to Cn aliphatic or aromatic hydrocarbon radical or radical of the general formula

COR* where

R* represents a C1 to C14 aliphatic or aromatic hydrocarbon radical,

X is chlorine, bromine, iodine or a mixture thereof, a is a number 0, 1 or 2, b is a number from 1 to 4 inclusive, the sum of a + b having the value 3 or 4.

The titanium compound can be used singly or in mixtures and include compounds of the formulas

TiCb,

TiCii,

Ti(OCH3)Cl ₃ ,

TifOCeHsjCb,

Ti(OCOCH3)Cl ₃ and TifOCOCeHájCb.

The magnesium compound has a structure corresponding to the general formula

MgX ₂ where

X represents chlorine, bromine, iodine or a mixture thereof.

These magnesium compounds can be used singly or in combination and include compounds of the formulae MgCl, MgBr and Mgh. Of the magnesium compounds, anhydrous magnesium chloride is particularly preferred.

In the preparation of the catalysts used in the process according to the invention, about 0.5 to 56, preferably about 1 to 10, moles of magnesium compound are used per 1 mole of titanium compound.

Titanium compounds and magnesium compounds are advantageously used in a form that facilitates their dissolution in the electron donor compound, as set forth below,

An electron donor compound is an organic compound that is liquid at 26 °C and in which a titanium compound and a magnesium compound are soluble. Electron donor compounds are known either by this name or by the name of a Lewis base.

The term electron donor compounds refers to compounds such as alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers and aliphatic ketones. Of these electron donor compounds, alkyl esters of C1 to C4 saturated aliphatic carboxylic acids, _C2 to C5 and preferably C5 to C4 aliphatic ethers, C5 to C4 cyclic ethers and preferably C6 cyclic mono- or diethers, C5 to C6 and preferably C6 to C1 aliphatic ketones are preferred. The most preferred of these electron donor compounds are methyl formate, ethyl acetate, butyl acetate, ethyl ether, hexyl ether, tetrahydrofuran, dolan, acetone and methyl isobutyl ketone.

The electron donor compounds can be used individually or in mixtures.

About 2 to 85, and preferably about 3 to 10, moles of electron donor compound are used per mole of titanium.

The activating compound has a structure corresponding to the general formula

Al(R“j _c X' _d H _e where

X' represents chlorine or a group of the general formula OR"' and each of the symbols

R" and R'", which may be the same or different, represent a Ci to Cm saturated hydrocarbon radical; d represents a number from 0 to 1.5 e represents a number 1 or 0, with the sum of c + d + e being 3.

The activating compounds can be used individually or in combinations and are exemplified by the following compounds:

A1(C2H5)3,

A1(CzH5)2C1,

Al(i-C4Hg)3,

Al2(C2H5)3Cl3,

Al(i-CiH9)2H,

A1(CsH13)3,

A1(CsH17)3,

A1(C2H5]2H and

A1(C12H5)2(OC, ₂ H5).

In activating the catalysts used according to the invention, about 10 to 400 and preferably about 10 to 100 moles of activating compound are used per 1 mole of titanium compound.

The substances used as supports are solid porous substances in the form of particles which are inert to the other components of the catalytic composition and to the other active components of the reaction system. These supports include inorganic substances such as silica and/or alumina. The supports are used in the form of dry powders which have an average particle size of about 10 to 250, preferably about 50 to 150 µm. These substances are also porous and have a specific surface area of at least 3 and preferably at least 50 m ² /g. The activity of the catalyst or productivity is also improved when the silica has pores of dimensions of at least 7 nm and preferably at least 10 nm and larger. The support should be dry, i.e. it should not contain absorbed water. Drying of the support is carried out by heating to a temperature of at least 600 degrees Celsius. Alternatively, the support can be dried at a temperature of at least 200°C and then treated with 1 to 8% by weight of one or more of the aluminum alkyl compounds described above. This modification of the support with the aluminum alkyl compounds provides a catalyst system with increased activity and, using such a catalyst system, the resulting polymer particles also have improved morphology.

The catalyst used in the process according to the invention is prepared by first preparing a precursor from a titanium compound, a magnesium compound and an electron donor compound in the manner described below, then impregnating the carrier with this precursor and then treating the precursor impregnated in the carrier with an activating compound, in one or more stages, as described below.

The precursor is prepared by dissolving the titanium compound and the magnesium compound in the electron donor compound at a temperature from about 20°C to about the boiling point of the electron donor compound. The titanium compound may be added to the electron donor compound before, after, or simultaneously with the addition of the magnesium compound. Dissolution of the titanium compound and the magnesium compound may be aided by stirring and, in some cases, by heating the two compounds in the electron donor compound to reflux. After dissolution of the titanium compound and the magnesium compound, the precursor may be isolated by crystallization or precipitation with a C5 to C5 aliphatic or aromatic hydrocarbon such as hexane, isopentane, or benzene.

The crystallized or precipitated precursor can be isolated in the form of fine, freely moving particles with a mean size of about 10 to 100 µm and a bulk density of about 202 to about 535 kg/m ³ .

The precursor prepared in this way has a composition corresponding to the general formula

Mg _m Tit(OR) _n X _p [ED] _q where represents

ED electron donor compound, m number from 0.5 to 56, preferably from 1.5 to inclusive limits, n number 0, 1 or 2, p number from 2 to 116, preferably from 6 to 14, inclusive limits, q number from 2 to 85, preferably from 4 to 11, inclusive limits,

R is a Ci to C1 aliphatic or aromatic hydrocarbon radical or a radical of the general formula COR', where R' represents a 'Ci to C1 aliphatic or aromatic hydrocarbon radical and

X chlorine, bromine or iodine or a mixture thereof.

The index for elemental titanium (Ti) means the Arabic numeral one.

The precursor is then impregnated into the carrier in a weight ratio corresponding to about 0.033 to 1, and preferably 0.1 to 0.33, parts of precursor per 1 part of carrier.

The impregnation of the dried (activated) carrier with the precursor can be carried out by dissolving the precursor in an electron donor compound and then mixing the resulting solution with the carrier. When the carrier is impregnated with the precursor, the solvent is evaporated by drying at a temperature not exceeding 70 °C.

The carrier can also be impregnated with the precursor by adding it to a solution of the raw materials used for the preparation of the precursor in the electron donor compound. In this case, the precursor is not isolated from the solution. The excess electron donor compound is then removed by drying or by washing and drying at a temperature not exceeding 70 °C.

In order to be used in the process according to the invention, the precursor must be fully or partially activated, i.e. it must be treated with a sufficient amount of an activating compound to convert the titanium atoms contained in the precursor into an active state.

In preparing a useful catalyst, it is necessary to carry out the activation in such a way that at least the last activation step takes place in the absence of solvent, so that the fully active catalyst does not have to be dried to remove the solvent. Two procedures have been developed to achieve this goal.

According to the first method, the precursor is fully activated outside the reactor in the absence of solvent by dry mixing the impregnated precursor with the activating compound. In this dry mixing, the activating compound is used in an impregnated state in a carrier. In this method, a fully activated precursor is prepared without the need to heat the catalyst system above 50 °C before feeding it into the polymerization reactor.

According to a second preferred process, the precursor is partially activated in a polymerization reactor with an amount of activating compound to obtain a partially activated precursor in which the molar ratio of activator to titanium is up to about 10:1 and preferably about 4 to 8:1. This partial activation is preferably carried out in a hydrocarbon solvent suspension. The resulting product is then dried to remove the solvent at a temperature of 20 to 80°C, preferably ⁵⁰ to 70°C. The resulting product is in the form of a freely mobile particulate material and can be easily introduced into the polymerization reactor. The partially activated impregnated precursor can be introduced into the polymerization reactor, where the activation is completed with an additional activator, which may be the same or a different compound.

The additional activating compound and the partially activated impregnated precursor are preferably introduced into the reactor via separate lines. The additional activating compound may be injected into the reactor in the form of a solution in a hydrocarbon solvent such as isopentane, hexane or mineral oil. This solution typically contains about 2 to 30% by weight of the activating compound. The additional activating compound is added to the reactor in such an amount that, together with the amount of activating compound and titanium compound introduced in the form of the partially activated impregnated precursor, a total molar ratio of Al/Ti of 10 to 400, and preferably about 15 to 60, is achieved in the reactor. The additional amount of activating compound introduced into the reactor reacts with the partially activated impregnated precursor and completes the activation of the titanium compound directly in the reactor.

In a continuous gas phase process, such as the fluidized bed process described below, individual portions of the partially or fully activated precursor impregnated in the carrier are continuously fed into the reactor during the polymerization, optionally with the simultaneous introduction of separate portions of the activating compound required to complete the activation of the partially activated precursor, thus replacing the active sites of the catalyst that were consumed during the reaction.

The polymerization is carried out by contacting a stream of monomers in the gas phase, for example by the fluidized bed process described below, in the substantial absence of catalytic poisons such as moisture, oxygen, carbon monoxide, carbon dioxide and acetylene, with a catalytically effective amount of a fully activated precursor (catalyst) impregnated on a support, at a pressure and temperature sufficient to initiate the polymerization.

In order to achieve the desired density range of the copolymers, it is necessary to copolymerize with ethylene a sufficient amount of comonomers having a carbon chain of 3 or more carbon atoms such that the content of C3 to C1 comonomers in the copolymer is 1.0 to 15 mol. %. The amount of comonomer required to achieve this result depends on the particular comonomer or comonomers used.

The following table lists several different comonomers that can be used for copolymerization with ethylene to produce polymers having a density in the desired range at any given melt flow index. The table shows both the amount of comonomer required in the copolymer to achieve these properties and the required relative molar concentration of the comonomer relative to ethylene in the recycled monomer gas stream under reaction equilibrium conditions in the reactor.

mol. % required in the gas stream propylene 1-butene 1-pentene 1-hexene 1-octene

3.0 to 10 2.5 to 7.0 2.0 to 6.0 1.0 to 5.0 0.8 to 4.5

0.2 to 0.9 0.2 to 0.7 0.15 to 0.45 0.12 to 0.4 0.10 to 0.35

A fluidized bed reaction system that can be used in carrying out the process of the invention is illustrated in Figure 1. Reactor 10 consists of a reaction zone 12 and a rate-reducing zone 14.

The reaction zone 12 contains a bed of growing polymer particles, formed by polymer particles and a minor amount of catalyst fluidized by a continuous flow of polymerizable and modifying gaseous components formed by make-up gas and gas recycled to the reaction zone. In order to maintain the fluidized bed in a fluidized state, the mass flow rate of the gas through the bed must be greater than the minimum flow rate required for fluidization. Preferably, a mass flow rate of the gas through the bed of about

1.5 to about 10X higher, preferably about 3 to 6X higher, than the minimum gas mass flow rate required for fluidization (Gmf). The designation Gmf for the minimum gas mass flow rate required to achieve fluidization was proposed by C. Y. Wen and Y. H. Yu, "Mechanics of Fluidization", Chemical Engineering Progress Symposium Series, vol. 62, pp. 100-111 (1966).

It is important that the bed always contains particles to prevent the formation of "hot spots" and to trap and distribute the powdered catalyst in the reaction zone. At start-up, polymer particles are usually introduced into the reaction zone as a starting material before the gas flow is introduced. These particles may be identical to the polymer being produced or they may be different. If they are different, they are withdrawn with the polymer particles as the leading product. Finally, the fluidized bed expels the starting bed.

The partially or fully activated precursor (catalyst) used in the fluidized bed is preferably stored in a standby tank 32 under an atmosphere of an inert gas, such as nitrogen or argon.

Fluidization is achieved by high velocity of the gaseous recycle introduced into and through the bed, which is typically on the order of about 50 times higher than the velocity of the make-up gas. A fluidized bed usually appears as a dense mass of moving particles flowing in a free vortex created by the passage of the gas through the bed. The pressure drop across the bed is equal to or slightly greater than the weight of the bed divided by the cross-section of the bed, and is therefore dependent on the reactor geometry.

The make-up gas is introduced into the bed at the same rate as the rate of withdrawal of the polymer product particles. The composition of the make-up gas is determined by means of an analyzer 16 located above the bed. The gas analyzer determines the composition of the gas being recycled, and the make-up gas composition is adjusted accordingly to maintain a substantially steady state composition of the gas mixture in the reaction zone.

To ensure complete fluidization, recycle gas and optionally also a portion of the make-up gas are introduced into the reactor via an inlet 18 below the bed. A gas distribution plate 20 is located above the inlet 18 to assist in fluidizing the bed.

The portion of the gas stream that does not react in the bed forms the recycle gas, which is removed from the polymerization zone preferably by passing it through a zone 14 located above the bed, in which the velocity is reduced and the entrained particles fall back into the bed. Particle separation may be aided by the inclusion of a cyclone 22, which may either be part of the velocity reducing zone 14 or may be external to this zone. If necessary, the recycle gas may be passed through a filter 24, which is adapted to separate small particles at high flow rates and thus prevent dust from accumulating on the heat transfer surfaces and on the compressor blades.

The recycle gas is then compressed in compressor 25 and passed through heat exchanger 26, where it is stripped of the heat of reaction before being returned to the bed. By constantly removing the heat of reaction, there is no noticeable temperature gradient at the top of the bed. A temperature gradient exists in the lower 152 to 304 mm of the bed, between the temperature of the entering gas and the temperature of the rest of the bed. It has been observed that the bed almost immediately adjusts the temperature of the recycle gas above this 152 to 304 mm zone of the bed to the temperature of the bed, so that under steady-state conditions the temperature of the bed is essentially constant. The recycle gas is introduced into the bottom of the reactor through inlet 18 and into the fluidized bed through distributor plate 20. Compressor 25 may also be located downstream of heat exchanger 26 in the direction of flow.

The distributor plate 20 plays an important role in the operation of the reactor. The fluidized bed contains both the growing and formed polymer particles and the catalyst particles. Since the polymer particles are hot and may be active, their settling must be prevented, since if any quiescent mass were to form, the active catalyst contained in these particles could cause the reaction to continue and the particles would melt due to the heat generated. It is therefore important that the dispersed recycle gas is passed through the bed at a rate sufficient to fluidize the particles at the bottom of the bed. The bottom of the bed is formed by a distribution plate 20, and this plate may be a screen, a slotted plate, a perforated plate, a plate with caps (analogous to the trays of a distillation column), etc. All parts of the plate may be stationary, or the plate may be of the moving type, such as the plate described in U.S. Patent No. 3,298,792. Whatever the structural arrangement of the plate, the plate must disperse the recycle gas among the particles at the bottom of the bed and maintain the particles of the bed in a fluidized state. The function of the plate is also to support the quiescent bed of resin particles when the reactor is not in operation. The moving parts of the plate may be used to displace polymer particles trapped on or in the plate.

Hydrogen can be used as a chain transfer agent in the polymerization of the invention. The hydrogen/ethylene molar ratio that can be used is in the range of about 0 to about 2.0 moles of hydrogen per mole of monomer in the gas stream.

Any gas that is inert to the catalysts and reactants may also be present in the gas stream. The activating compound is preferably added to the gas recycle system at its hottest point. Therefore, the activator is preferably introduced into the recycle line downstream of the heat exchanger, such as from reservoir 27 via line 27A.

As molecular weight control agents, i.e. as chain transfer agents, compounds of the general formula can be used together with the catalysts according to the invention in addition to hydrogen.

Zn(R _a )(R _b ) where

R _a and R _b are the same or different C 1 to C 14 'aliphatic or aromatic hydrocarbon radicals.

This results in a further increase in the melt flow index values of the produced copolymers. The gas stream fed into the reactor

1 5 0 15 may be added about 0 to 50 and preferably about 20 to 30 moles of zinc compound (calculated as Zn) per mole of titanium compound (calculated as Ti). The zinc compound may be introduced into the reactor preferably in the form of a dilute solution (at a concentration of 2 to 10% by weight) in a hydrocarbon solvent or in absorbed form in a solid diluent such as silica, in an amount of about 10 to 50% by weight. These substances tend to be pyrophoric. The zinc compound may be introduced into the recycle gas stream from a dispenser adjacent to the dispenser 27.

The fluidized bed reactor must operate at a temperature below the sintering temperature of the polymer particles. In order to prevent sintering of the particles, it is necessary that the operating temperature is below the sintering temperature. In the production of ethylene copolymers by the process according to the invention, it is preferable to operate at a temperature of about 30 to about 105 °C, most preferably at a temperature of 75 to 95 °C. Temperatures of about 75 to 95 °C are used to produce products with a density of about 910 to 920 * kg / /m ³ and temperatures of about 80 to 100 °C are used to produce products with a density of about >920 to 940 ^: kg / m ³ .

The fluidized bed reactor operates at pressures up to about 6.87 MPa, preferably at pressures from about 1.0*3 to 2.40 MPa, and when operating at higher pressures in this range, heat transfer is facilitated because the increase in pressure results in an increase in the unit volume heat capacity of the gas.

The partially or fully activated precursor is injected into the bed at a rate equal to the rate at which it is consumed through a feed 30 located above the distributor plate 20. An important feature of the invention is that the catalyst is injected at a location above the distributor plate. Since the catalysts used in the invention are highly active, injection into the space below the distributor plate could result in the initiation of polymerization at that location, which could ultimately lead to clogging of the distributor plate. Injecting the catalyst into the fluidized bed, on the other hand, helps to distribute the catalyst in the bed and prevents the formation of areas of high catalyst concentration that could lead to hot spots.

A gas that is inert to the catalyst, such as nitrogen or argon, is used to introduce the partially or fully reduced precursor and any activating compound or transfer agent that is not in the gaseous state into the bed.

The productivity of the bed is controlled by the catalyst injection rate. The productivity of the bed can be increased simply by increasing the catalyst injection rate and decreased by decreasing it.

Since any change in the catalyst injection rate results in a change in the rate of heat development of the reaction, the temperature of the recycle gas entering the reactor is adjusted up or down to accommodate the changes in the rate of heat development. This ensures that the bed temperature is maintained at a substantially constant level. Both the fluidized bed and the recycle gas cooling system must, of course, be equipped with appropriate instruments for detecting changes in the bed temperature and the cooling system so that the operator can make appropriate adjustments to the recycle gas temperature.

Under certain combinations of operating conditions, the fluidized bed is maintained at substantially the same height by withdrawing a portion of the bed as product at the same rate as the rate of formation of polymer product particles. Since the rate of heat evolution is directly proportional to the rate of formation of the product, the rate of formation of polymer particles at constant gas velocity is determined by measuring the rise in gas temperature across the reactor (i.e., the temperature difference between the temperature of the entering gas and the temperature of the leaving gas).

The polymer product particles are preferably withdrawn continuously through line 34 or near the distributor plate 20. The particles are withdrawn in suspension with a portion of the gas stream being vented before the particles settle to prevent further polymerization and caking before the particles reach the zone where they are collected. The suspension gas, as previously mentioned, can also be used to transfer the product from one reactor to another.

The polymer product particles are conveniently and preferably withdrawn by means of two sequentially operating, timed valves 36 and 38, between which a separation zone 40 is provided. When valve 38 is closed, valve 36 is opened, allowing the gas/product mixture to pass into zone 40. Valve 38 is then opened to transfer the product to an outer isolation zone. Valve 38 is then closed and remains closed until the next product withdrawal.

Finally, the fluidized bed reactor is equipped with a suitable venting system that allows venting during start-up and shut-down. The reactor does not require the use of any stirring devices and/or wall scraping devices.

The highly efficient supported catalyst system used in the invention provides a fluidized bed product with a mean particle size of about 0.25 to 1.78 mm, preferably between about 0.45 and 0.90 mm, with unusually small amounts of supported catalyst residue in the polymer. The polymer particles are relatively easily suspended in the fluidized bed process. The polymer product contains relatively small amounts of dust particles (less than 150 μm), i.e. less than 4% by weight.

The feed stream of gaseous monomer, optionally with inert gaseous diluents, is introduced into the reactor at a rate to achieve a space-time yield of about 32.4 to about 162.2 kg/h/m ³ of bed volume.

The term "raw resin or polymer" herein refers to the polymer in granular form as obtained from the polymerization reactor.

The following examples serve to further illustrate the invention, but do not limit the scope of the invention in any way.

The properties of the polymers produced in the examples are determined by the following test methods:

Density

A test plate is fabricated and annealed at 100°C for 1 hour to approach the equilibrium crystallinity state. Density measurements are then performed in a density gradient column.

Melt flow index (MI)

ASTM D-1238-Condition E measurement is performed at 190 °C, results in g per 10 minutes.

Flow rate (High Load Melt Flow Index) (HLMI)

ASTM-D-1238-Condition F measurement is performed using ten times the load than when measuring melt flow index

The ratio of the speeds _{of the y} and _{y axes} , _t of the flow = -—— -;flow index -melt

Productivity

A sample of the resin product is ashed and the ash percentage is determined by weight, since the ash is essentially composed of catalyst. The productivity is therefore given in kg of polymer produced per kg of total catalyst consumed. The amounts of titanium, magnesium and chlorine in the ash are determined by elemental analysis.

Bulk (volumetric) weight

The resin is poured into a 100 ml graduated cylinder using a funnel with a stem diameter of 9.5 mm up to the 100 ml nozzle. The cylinder is not shaken during filling. The difference in weight is determined by weighing.

Molecular weight distribution (Mw/ /Mn)

It is determined by gel chromatography on Styrogel with a pore size sequence of ΙΟ ⁶ , 10 ⁴ , 103 , 10 ² , 6 nm. Perchloroethylene is used as a solvent at 117 °C. Detection is performed by infrared radiation at 3.45 μm. Evaluation of the foil

The film sample is observed with the naked eye to determine the size and distribution of gel particles or other foreign particles compared to a standard film sample. The appearance of the film is thus compared to the standard samples and rated with an appropriate grade on a scale from -100 (very poor film) to +100 (excellent film).

n-Hexane extractables (FDA-Test used for polyethylene films intended to come into contact with food). A film sample with a thickness of 38.1 μm and an area of 1290 ^cm2 is cut into strips measuring 2.54 X 15.24 cm and weighed to the nearest 0.1 mg. The strips are placed in a container and extracted with 300 ml of n-hexane at a temperature of 50+1 °C for 2 hours. The extract is then decanted into a balanced culture dish. After drying the extract in a vacuum desiccator, the culture dish is weighed to the nearest 0.1 milligram. The amount of extract converted to the original weight of the sample is then reported as the mass fraction of n-hexane extractables.

Unsaturated

The measurement is carried out using an infrared spectrophotometer (Perkin Elmer Model 21). Extrusions of 0.635 mm thick are made from the resin and serve as test specimens. The absorbance is measured at 10.35 /m in the case of trans-vinylidene unsaturation, at

I. 1.0 /grain in the case of terminal vinyl unsaturation and at 11.25 μΐη in the case of vinylidene unsaturation in the side chains. The absorbance per 1 mm of the thickness of the molding is directly proportional to the product of the unsaturation concentration and the absorbency. The absorbency values are taken from the literature (R. J. de Kock et al.,

J. Polymer Science. Part B, 2, 339 (1964)).

Example I

Preparation of impregnated precursor

In a 12 L flask equipped with a mechanical stirrer, 41.8 g (0.439 mol) of anhydrous magnesium chloride and 2.5 L of tetrahydrofuran (THF) are placed. To this mixture, 27.7 g (0.184 mol) of titanium tetrachloride are added dropwise over 1/2 hour. It may be necessary to heat the mixture to 60 °C for about 1/2 hour to completely dissolve the substance.

The precursor can be isolated from solution by crystallization or precipitation and then analyzed for magnesium and titanium content, since some amount of magnesium and/or titanium compound may be lost during the isolation of the precursor. The empirical formulas used herein to characterize the composition of the precursor are derived assuming that the magnesium and titanium still exist in the form of compounds that were originally added to the electron donor compound. The amount of electron donor compound is determined chromatographically.

To the above solution, 500 grams of porous silica, dried at a temperature of up to 800 °C and optionally treated with 4 to 8% by weight of triethylaluminum, are added and the mixture is stirred for 1/4 hour. The mixture is dried by blowing nitrogen at 60 °C for about 3 to 5 hours. A dry, free-moving powder is obtained, which has the same particle size as the silica particles used. The absorbed precursor has a composition corresponding to the formula

TlMg _M Cl ₁₀ (THF) ₆₍₇

P ř 1 k 1 a d I b

Preparation of impregnated precursor from pre-prepared precursor

In a 12 L flask equipped with a mechanical stirrer, 140 g of the precursor are dissolved in

2.5 L of dry THF. The solution may be heated to 60°C to facilitate dissolution. 500 g of porous silica are added and the mixture is stirred for 1/4 hour. The mixture is then dried by purging with a stream of nitrogen at a temperature not exceeding 60°C for about 3 to 5 hours. A dry, free-flowing powder is obtained which has a particle size similar to that of the silica particles.

They applied

Activation procedure

The required weight of the impregnated precursor and the activating compound is placed in a mixing drum, together with a sufficient amount of an anhydrous aliphatic hydrocarbon diluent, such as isopentane, to form a suspension.

The activating compound and the precursor are used in such amounts as to obtain a partially activated precursor having an Al/Ti ratio greater than 0 but less than or equal to 10. The preferred ratio is 4 to 8:1.

The suspension is stirred thoroughly at room temperature and atmospheric pressure for 1/4 to 1/2 hour. The resulting suspension is dried with a stream of dry, inert gas, such as nitrogen or argon, at atmospheric pressure and at a temperature of 65+10°C, to remove the hydrocarbon diluent. This usually takes about 3 to 5 hours. The resulting catalyst is in the form of a partially activated precursor impregnated in the pores of the silica. The substance is in the form of a freely moving powdery material. The particles correspond in size and shape to the particles of silica. The product is not pyrophoric if the alkylaluminum content is not more than 10% by weight. It is kept under dry inert gas, such as nitrogen or argon, until it is used. It is ready for introduction into the polymerization reactor, where complete activation is then carried out.

When additional activating compound is introduced into the polymerization reactor to complete the activation of the precursor, it is fed into the reactor in the form of a dilute solution in a hydrocarbon solvent, such as isopentane. These dilute solutions contain from about 5 to about 30% by volume of the activating compound.

The activating compound is introduced into the polymerization reactor in such an amount that the Al/Ti ratio in the reactor is maintained at a value of from 10 to 400:1, preferably from 15 to 60:1.

: 1.

Examples 1 to 6

In each of these 6 examples, ethylene is copolymerized with 1-butene

Examples 1 to 3 used the catalyst prepared as described above. The silica-impregnated catalyst system used in Examples 1 and 2 contained 14.5% by weight of precursor and the silica-impregnated catalyst system used in Example 3 contained 20.0% by weight of precursor. The silica used as the catalyst support in Example 2 was treated with triethylaluminum before being used to prepare the supported catalyst.

The catalysts used in Examples 4 to 6 were prepared by methods that are not within the scope of the invention and are for comparison purposes. The catalyst of Example 4 is prepared by physically mixing 7.5% by weight of the unimpregnated precursor prepared in Example Ia with 92.5% by weight of polyethylene powder. The polyethylene powder is a high-pressure copolymer of ethylene with a low density (below 940 kg/ ^m3 ) having an average particle size of about 50 to 150 µm. The catalyst used in Examples 5 and 6 is prepared by physically mixing 20% by weight of the unimpregnated precursor prepared in Example Ia and 80% by weight of silica having a specific surface area of 300 ^m2 /g and an average particle size of 70 µm. In each of Examples 1 to 6, the precursor is partially activated with triethylaluminum to obtain an alumina-precursor system with an Al/Ti molar ratio of 5+1. The completion of the activation of the precursor in the polymerization reactor is carried out with a 5% (w/w) solution of triethylaluminum in isopentane to obtain a fully activated catalyst in the reactor with an Al/Ti molar ratio of 25 to 30.

Each of the reactions is carried out in a fluidized bed reaction system for 1 hour after reaching equilibrium at 85°C and 2.00 MPa at a gas velocity of about three to six times the Gmf and a space-time yield of 71.3 to 10'2.2 kilograms/m ² /'h. The reaction system described above is used, as shown in the figure. Its lower part is 3.05 m high and its inner diameter is 0.343 m. The upper part is 4.83 m high and its inner diameter is 0.597 m.

Table I shows the 1-butene-ethylene molar ratio, the H2/ethylene molar ratio and the yield per unit time and space (kg/h/ ^m3 bed space) in each example, various properties of the polymers produced and various properties of film samples produced from these polymers.

Compared to granular copolymers made according to U.S. Patent Application No. 892,235 filed March 31, 1978 (F. J.

Karol et al., Preparation of Ethylene Copolymers in a Fluidized Bed Reactor), the copolymers of the invention in the raw powder state at a given density and melt flow index have a smaller mean particle size, a narrower molecular weight distribution, are easier to fluidize, have a higher bulk density, and are easily pneumatically transported. Films made from copolymers made by the method of the invention have significantly better properties than films made from copolymers made according to the cited patent application.

Table I

Example 2 1 3 4. 5 •6 Working conditions molar ratio C4/C2 0.448 0.472 0.402 0.462 0.423 0.4011 molar ratio H2/C2 0.193 0.215 0.535 0.204 0.207 0.394 yield based on a unit of time and space (kg/h/m ³ bed space) 87.5 102.2 84.3 71.3 85.9 — Polymer properties Melt flow index (g/10 min) 1.8 2.2 17.8 2.3 1.3 15.7 Melt flow rate ratio 25.3 25.1 23.7 25.5 25.3 25.0 Density (kg/ ^m3 ) 923.8 920.8 927.8 924 923 928 Ti (ppm) 5—6 5—6 7—9 2—3 2—3 1 % ash 0.042 0.049 0.059 — 0.034 0.034 Film Features Gloss (O/o) 159 141 — — _ — Turbidity (θ/ο) 9.7 13.6 — .— — — Extractables content hexane (%) 0.17 0.41 — — — —- Film Rating + 30 + 25 _ + 40 —60 — Granulate properties Density (kg/m ³ ) 339 313 404 235 259 271 At _mf (m/s) 0.14 •0.19 0.08 0.40 0.20 —. U, _11X (m/s) 0.26 0.37 0.21 0.64 0.34 — Sieve analysis (% by weight) Sieve size — 8 mesh 1.4 1.8 0.0· 7.7 17.4 1.3 12 mesh 4.4 8.7 0.4 28.5 14.4 2.5 20 mesh 27.7 38.7 13.4 42.9 28.4 11.4 40 mesh 40.2 37.1 47.9. 15.9 19.0 41.9 60 mesh 16.7 11.0 25.3 4.0 9.1 25.4 100 mesh 7.0 2.2 9.4 0.6 8.1 14.7 bowl 2.6 0.6 3.6 0.2 3.4 2.8 Mean particle size (mm) 0.822 0.95 0.559 1,488 1,377 0.584 Examples 7 to 10 with gained infused precursor with molar

In each of these examples, ethylene is copolymerized with 1-butene.

In these examples, the catalyst precursor impregnated into silica is prepared as described above. The catalyst system impregnated into silica contains 20.0% by weight of the precursor. The silica support used to prepare the catalysts in these examples is treated with triethylaluminum prior to precursor impregnation. In each of these examples, the precursor is partially activated with the aluminum compound shown in Table II as described above, such that the Al/Ti ratio shown in Table II.

The activation of the precursor in the polymerization reactor is completed with a 5% (w/w) solution of triethylaluminum in isopentane to obtain a fully activated catalyst in the reactor with an Al/Ti molar ratio of 25 to 30.

The polymerization reactions are carried out in the same manner as in Examples 1 to 6.

Table II shows the values of the molar ratio of Al/Ti in the preparation of the precursor, the molar ratio of 1-butene/ethylene, H2//ethylene, the yield, relative to space and time [kg/h/ ^m3 ] in each example, and the various properties of the polymers obtained.

Table II

Example 2 7 8 9 10 Precursor activation Activating compound ¹ TEAL TIBAL TIBAL TNHEXAL TNOCTAL Molar ratio Al/Ti 4.5 6.7 4.5 6.6 7.5 Working conditions Molar ratio C4/C2 0.448 0.375 0.369 0.375 0.368 Molar ratio H2/C2 0.193 0.2166 0.247 0.266 0.249 Yield related to space and time [kg/h/rn ³ bed space] 87.5 94.0 81.1 85.9 126.5 Polymer properties Melt flow index [g/10 min] 1.8 2.8 1.1 2.9 2.2 Melt flow rate ratio 25.3 29.9 25.5 28.4 26.4 Density [kg/ ^m3 ] 923.8 920 928 921 923 Ti [ppm] 5—6 3—5 2-4 3—5 2—4 % ash 0.042 0.037 0.030 0.036 0.023 Granulate properties Density [kg/m ³ ] 339 415 319 425 344 mean particle size [mm] 0.823 11,240 1,252 1,176 1,367

^X TEAL = triethylaluminium Examples whose parameters are given

TIBAL — tri-isobutylaluminium in Table II, show that copolymers with high bulk density, low TNHEXAL = tri-n-hexylaluminium content

TNOCTAL = tri-n-octylaluminium with catalytic residues and good properties can be prepared using catalysts according to the invention, which were prepared using two different activating compounds.

Claims (3)

SUBJECT Process for the catalytic production of an ethylene copolymer using a catalyst containing titanium at a productivity of 50,000 kg polymer per kg of titanium in a reactor at a pressure below 6.87 mPa in a gas phase, the polymer being formed in granular form and having a density of 910-940 kg / m ³ , including limit values, and a melt flow rate ratio of 22 to 32, including limit values, characterized in that the ethylene is copolymerized with at least one C 5 to C 8 alpha-olefin at a temperature of 30 to 105 ° C by monomer the batch contacts in the presence of 0 to 2.0 moles of hydrogen per mole of ethylene in the reaction zone and in the gas phase with particles of a catalyst system consisting of a precursor of the general formula Mg _m Ti (OR) _n X _p [ED] _q where represents ED electron donor compound, m number from 0.5 to 56 including limit values, n number 0, 1 or 2, p number from 2 to 116 including limit values, q number from 2 to 85 including limit values, R 1 to C w is an aliphatic or aromatic hydrocarbon radical or a radical of formula COR ‘, where R‘ represents a C 1 to C 14 aliphatic or aromatic hydrocarbon radical, X chlorine, bromine or iodine, or a mixture thereof, which is impregnated into a porous support and is initially partially activated outside the reactor by not more than 10 moles of activating compound per mole of titanium contained in the precursor and then fully activated either outside the reactor> 10 to 400 moles of activating compound mole of titanium in the precursor, wherein complete activation is effected to form a solid dry catalyst system prior to feeding the system to the polymerization reactor, without the need to heat it to above 50 ° C during those activation stages that are carried out with a quantity of activation. of the compound above 10 moles, or fully activated in the reactor> 10 to 400 moles of activating compound per mole of titanium contained in the precursor, the activating compound being a compound of the general formula Al (R ') _c X _d ' H _e where X ‘represents chlorine or a group of the formula OR" ‘and each symbol R "and R" ', which are the same or different, represent a C 1 -C 10 saturated hydrocarbon radical, d is a number from 0 to 1.5, e is a number of 1 or 0, the sum of c + d + e being 3 , and the electron donor compound is a liquid organic compound in which the precursor is soluble, selected from the group consisting of alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers and aliphatic ketones. 2. A process according to claim 1, wherein the process is carried out in a fluidized bed. 3. The process of claim 1 wherein the precursor is partially activated with no more than 10 moles of activating compound outside the reactor and then fully activated within the reactor with an amount of activating compound such that an Al / Ti molar ratio is achieved in the reactor.