FI112242B - Increasing the activity of Ziegler-Natta olefin polymerisation catalysts - Google Patents

Abstract

A process for increasing the activity of a Ti-based Ziegler-Natta type catalyst during an olefin polymerisation reaction comprises using the catalyst in the presence of a halogenated hydrocarbon (I) in an amt. such that the mol ratio (I) to Ti in the catalyst is 0.001-0.2.

Description

! 112242

Use of a halogenated hydrocarbon compound to increase catalyst activity

The invention relates to the use of halogenated hydrocarbons as catalyst activators in the polymerization of olefin in the presence of Ziegler-Natta-type titanium based catalysts.

It is known to polymerize olefins, e.g. ethylene, in particular by the gasase polymerization process with the aid of a Ziegler-Nat-10 ta type catalyst and an organometallic cocatalyst. When the catalyst is very active, especially when used in the presence of a large amount of cocatalyst, the formation of polymer agglomerates can be observed, which can be considerable.

EP-A-0 529 977 discloses gas phase polymerization of ethylene with a Ziegler-Natta-type catalyst containing titanium in the presence of a halogenated hydrocarbon compound which makes it possible to substantially reduce the formation of ethane. Under the conditions used in the process of that patent application, no significant variation in average catalyst yield was observed.

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* '' Activity.

· - · The use of a halogenated hydrocarbon compound in a process which allows a significant increase in catalyst activity in olefin polymerization has now been discovered. (i P Practically no formation of polymer agglomerates was observed during the process although the catalyst was very active and was used in the presence of a relatively large amount of cocatalyst.

The invention thus relates to the use of a halogenated hydrocarbon compound to increase the catalytic activity in the continuous (co) polymerization of one or more olefins, which: is carried out on a Ziegler-Natta-type titanium-based catalyst: , tin containing essentially no other transition metals, ···, 35, and in the presence of an organometallic cocatalyst, the amount of halogenated hydrocarbon used is such that the molar ratio of the amount of halogenated hydrocarbon compound to the amount of polymer introduced in the polymerization medium is greater than 0.001 and less than 0.15.

In one aspect, the invention relates to a use characterized in that the molar ratio of the amount of halogenated hydrocarbon compound to the amount of titanium introduced into the polymerization medium is 0.01 to 0.1, i.e. greater than 0.01 and less than 0.1.

Figure 1 is a diagram illustrating a fluidized bed reactor in which the gas phase (co) polymerization of ethylene takes place according to Example 1 of the application. Figure 2 shows a plot of catalyst activity (in units of gram of (co) polymer produced per millimole of titanium per hour of reaction and 0.1 MPa of ethylene) as a function of the molar ratio of chloroform: titanium to 15 introduced into the polymerization medium during run A-F of the Example Example.

The process uses a halogenated hydrocarbon compound to increase the activity of a Ziegler-Natta-type titanium-based catalyst. The activity represents the amount of polymer produced under certain re-20 action conditions. For example, catalyst activity can be measured as the amount of polymer produced per mole of titanium per hour of reaction and? · ·: 0.1 MPa per ethylene pressure.

The halogenated hydrocarbon compound may be a chlorinated hydrocarbon or a brominated hydrocarbon. It may be a monohalogenated hydrocarbon, e.g. of the formula RX wherein R is an aralkyl or aryl group having from 1 to 10 carbon atoms, preferably from 1 to 4 carbons, preferably from 6 to 14 carbons, preferably from 6 to 10 carbons. and X is a halogen atom such as chlorine or bromine.

The halogenated hydrocarbon may also be a polyhalogenated hydrocarbon containing preferably 2 to 6, e.g. 2 to 4 halogen atoms such as chlorine or bromine, and 1 to 14, e.g. -4 • · · · ,,,! carbon atoms in one molecule. Preferably, it can also be a mono- or polyhalogenated saturated hydrocarbon, precursor to the halogenated hydrocarbon compounds previously mentioned, e.g., methylene chloride, chloroform, carbon tetrachloride, 112242 di, trichloro-1,1,1-ethane. or dichloro-1,2-ethane. Most often chloroform is used.

The halogenated hydrocarbon compound may be introduced into the polymerization medium as such or preferably diluted in a liquid hydrocarbon such as an alkane, e.g. iso-pentane, n-pentane, n-hexane or n-heptane.

It is highly preferred to use the halogenated hydrocarbon in the (co) polymerization reaction in an amount such that the molar ratio of halogenated hydrocarbon to titanium introduced into the polymerization medium is 0.001 to 0.15, preferably 0.01 to 0.1 or 0.03 to 0.1, and more particularly 0.03 to 0.095, e.g. 0.031 to 0.091. Using these amounts of halogenated hydrocarbons, a large increase in catalyst activity is unexpectedly observed. Usually it is at least 10%. In most cases, it can be greater than about 20% and even greater than about 100%. The increase in catalyst activity is particularly observed when the (co) polymerization reaction is continuous, especially in the gas phase polymerization process.

In the (co) polymerization of one or more olefins, e.g., 2 to 8 carbon atoms, such as ethylene or ethylene, and at least one C 3 -C 6 -olefin, the olefin (s) is continuously introduced into a polymerization medium preferably at (co) ) lower than the melting point of the polymer, e.g. 30-120 ° C, preferably 50-110 ° C or 60-100 ° C, and a pressure of 0.1-5 MPa, preferably 0.5-4 MPa, e.g. 1-3 MPa. Also, the catalyst and the organometallic cocatalyst are introduced continuously or semi-continuously, i.e. intermittently, into the polymerization medium and the resulting polymer is removed from the polymerization medium continuously. image or semicontinuously, ie intermittently. If necessary, the Mole Controller may be continuously introduced into the polymerization medium. Preferably, the catalyst and the halogenated hydrocarbon compound can be used or introduced into the polymerization medium in a molar ratio of the amount of halogenated hydrocarbon compound to the amount of titanium introduced. 35 substantially constant in the above-mentioned region.

4, 112242

The polymerization medium may be a liquid hydrocarbon diluent which forms a suspension with the catalyst and the (co) polymer. It may be an alkane or a cycloalkane or a mixture of alkanes or cycloalkanes containing e.g. 3-10, preferably 4-8 carbon atoms, e.g. n-hexane. It may also be a gas phase containing one or more olefins, optionally mixed with hydrogen and an inert gas.

Preferably, the polymerization process is a continuous gas phase (co) polymerization of one or more to 10 larger olefins, e.g., 2 to 8 carbons, such as ethylene or ethylene, and at least one C 3-8 olefin. In this case, the polymerization medium comprises an olefin stream passing upward through a finely divided mixed (co) polymer mattress, and the (co) polymerization heat is removed by cooling the olefin stream, which is then circulated to the mixed mattress. The mixed mattress may be a whipped mattress, or preferably a fluidized bed, wherein the olefin stream is a fluidizing gas that holds the finely divided (co) polymer in a fluidized state. The olefin stream may comprise a mixture of one or more olefins, e.g., ethylene or ethylene, and at least one C3-8-olefin, a molecular weight regulator, e.g. hydrogen, and an inert gas such as nitrogen or always. at least one C 1-8 alkane, preferably at least one C 2-8 alkane.

t; · 2 In the invention, the halogenated hydrocarbon compound is preferably continuously introduced into a polymerization medium, e.g.

as a solution in a liquid hydrocarbon such as an alkane, a cycloalkane or a mixture thereof containing, for example, 3 to 10, preferably 4 to 8, carbon atoms, especially »| *.,! 30 if the (co) polymerization of the olefin (s) occurs continuously. The halogenated hydrocarbon compound may be used in an amount of 0.1 to 100%; * ·· preferably 1 to 50% by weight as a solution in a liquid substance or cycloalkane.

When the molar ratio of the amount of halogenated hydrocarbon is poly- »'!!! When the amount of titanium introduced into the fermentation medium is too high, it has been found that the catalyst activity is not significantly altered or even substantially reduced, especially during the continuous polymerization process. When the ratio is too low, no significant change in catalyst activity is observed compared to the process occurring in the absence of the halo-5-generated hydrocarbon compound.

Further, the halogenated hydrocarbon compound may also be used in an amount such that the molar ratio of the amount of halogenated hydrocarbon to the total amount of co-catalyst introduced into the polymerization medium is 0.001 to 0.5, preferably 0.005 to 0.25, and especially 0.005 to 0.15, e.g. 0.15. Preferably, the cocatalyst and the halogenated hydrocarbon compound can be used or introduced into the polymerization medium to maintain a substantially constant molar ratio of the amount of halogenated hydrocarbon to the amount of titanium introduced into the polymerization medium selected from the above range.

The polymerization catalyst is a titanium-based catalyst, which means that it contains essentially no other transition metals and, in particular, it does not contain substantially vanadium.

The catalyst may be one containing oleic acid. Titanium, halogen and magnesium, and optionally non-fusible oxide, e.g. silicon or aluminum, as its atoms. It may be prepared by a process comprising magnesium metal, at least one halogenated hydrocarbon and; Is at least one of the requisites between at least one tetravalent titanium compound, such as disclosed in FR-* · · Patent Nos. 2,099,331 and 2,116,698.

The catalyst may comprise a granular support which is based, in particular, on non-melting oxide such as silicon and / or aluminum. Such a catalyst may be prepared by a process in which the granular support is contacted with (a) dialkylmagnesium and optionally trialkylaluminum, (b) a halogenated hydrocarbon, e.g., "Il 35 monohalogenated hydrocarbon, and (c) a tetravalent hydrocarbon. 112242. Such a method is disclosed in European Patent Application 453 088.

The catalyst may also contain a magnesium chloride support, and in particular a preactivated support such as that disclosed in, for example, European Patent Application 336,545. A catalyst of this type may be prepared by a process of contacting (a) an organometallic compound, a titanium reducing agent with a tetravalent titanium compound; and (c) lightly with one or more electron donor compounds. Such a method is disclosed in FR Patent Application 2,669,640.

The catalyst may be used in solid form as such or in the form of a prepolymer, especially when used in gas phase polymerization. The prepolymer is obtained by contacting the catalyst with one or more olefins containing, for example, 2 to 8 carbon atoms, such as ethylene or a mixture of ethylene and C3-8-olefin (s) in the presence of an organometallic cocatalyst. Generally, the resulting prepolymer contains from 0.1 to 200 g, preferably from 10 to 100 g, of polymer per mole of titanium.

: "The catalyst is used with an organometallic cocatalyst, which may be an organoaluminum, organomagnesium or, organosinctate T. In most cases, the organometallic; Then a mixture of these compounds.

In the invention, the organometallic cocatalyst can be used in a relatively large amount, and in particular so that the molar ratio of the total amount of organometallic cocatalyst to the amount of titanium introduced into the polymerization medium is 0.5-100, preferably 0.7-40, more particularly 1 , 2 - 20, e.g. 1,5 - ίο.

The organometallic cocatalyst can be introduced continuously 35 or half continuously, i.e. intermittently into the polymerization medium, in admixture with a catalyst such as a prepolymer or separately from the catalyst. In one particular process, a portion of the organometallic cocatalyst is introduced into the polymerization medium in admixture with the catalyst and another portion is provided separately from the catalyst. For example, it is possible to use a prepolymer containing an organometallic cocatalyst in an amount such that the molar ratio of organometallic cocatalyst to titanium is 0.5 to 5, preferably 1-4, and to separately add to the polymerization medium an organometallic cocatalyst in an amount of the titanium content is from 1 to 10.

The (co) polymerization reaction can be carried out in suspension in a liquid hydrocarbon. However, it is particularly advantageous to carry it out in the gas phase by known methods in a reactor comprising a mechanically whipped and / or fluidized bed, in particular with the equipment disclosed in FR patents 2 207 145 and 2 335 526.

In gas phase (co) polymerization, the olefin stream may contain hydrogen in an amount such that the molar ratio of hydrogen to the total amount of olefin (s) used is from 0.05 to 1.0, preferably from 0.15 to 0.5. However, this ratio may be higher than 1, especially in the manufacture of a (co) polymer having a high melting index: for example, a (co) polymer having a melt index MI 2, 16 (measured at 190 ° C of 2.16 kg fid * load) is greater than 50 g / 10 minutes.

The use according to the invention can be applied in a process capable of preparing ethylene (co) polymers optionally containing one or more alpha-olefins, e.g. containing from 3 to 8 carbon atoms, such as for example, 1-butene, 1-hexene, 4-methyl-1-pentene or 1-octene. The density of these (co) polymers may be from? 0.965 to 0.910. The invention is particularly advantageous in the preparation of ethylene and at least one alpha-olefin, e.g.

: C3-8 alpha-olefin copolymers having a density of 0.948-0.960 and a melt index MI2 of 16-25 g / 10 minutes. It's you- '!!! It is also possible to prepare well-proportioned * * 112242 ethylene copolymers having a density of 0.914-0.930 and a melt index MI2 of 16- 0.5 g / 10 minutes.

The titanium content of the (co) polymers obtained by the process is particularly low, it may be less than 15 ppm or even less than 5 ppm, and in most cases less than 5 ppm, e.g. 1-5 ppm. Furthermore, these (co) polymers surprisingly have a higher melt index compared to (co) polymers obtained under the same conditions but without the halogenated hydrocarbon compound. In particular, the melt index, measured at 190 ° C with a load of 2.16 kg, can double. The melt index may vary in harmony with the catalyst activity.

In addition, the soluble polymer content of the (co) polymers obtained by the use of the invention may be less than 15 than that of the (co) polymers prepared without the halogenated hydrocarbon compound. This result is observed in particular in the preparation of (co) polymers by means of a catalyst consisting essentially of titanium, halogen and magnesium atoms and prepared, for example, by reaction of magnesium metal, halogenated hydrocarbon and at least one tetravalent titanium compound. The decrease in soluble polymer length may be greater than 20%. In the invention, the soluble polymer content of the (co) polymer is measured after keeping the (co) polymer in n-hexane at 50 ° C; 25 2 hours. This concentration is expressed as a percentage by weight.

Preferably also by use in accordance with the invention. The content of oligomers of (co) polymers obtained may be substantially lower compared to (co) polymers prepared without a halogenated hydrocarbon compound. In most cases, it was also found that the molecular weight distribution of the (co) polymers was reduced compared to the (co) polymers obtained without the halogenated hydrocarbon compound.

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The following examples illustrate the invention.

Example 1 a) Preparation of Catalyst 4.6 m 3 of n-hexane, 5.5 kg of iodine, 3 160 moles of magnesium 5 moles, 29 moles of isobutanol, 60 moles of titanium tetra-n-propoxide and 60 moles of n-butyl chloride were introduced. reactor fitted with a mechanical agitator system rotating at 150 rpm. The reactor was then heated to 85 ° C until the reaction started and then to 80 ° C. At this temperature, 400 mol of titanium tetrachloride, 340 mol of titanium tetra-n-propoxide, and then 4 700 mol of n-butyl chloride were introduced into the reactor at 240 minutes. The resulting mixture was kept stirred at 80 ° C for 2 hours. This gave the catalyst as a suspension in n-hexane.

B) Preparation of the prepolymer 500 l of n-hexane, 4 mol of tri-n-octylaluminium and an amount of a previously prepared catalyst containing 2.5 mol of titanium were introduced into a 1.5 m3 stainless steel reactor which was kept under nitrogen was a rotary mixer at 20,150 rpm and heated to 70 ° C. Hydrogen was then introduced to give a partial pressure of 0.1 MPa and ethylene at a constant flow rate of 15 kg / h for 6 hours 40 minutes. After this time, the reactor was degassed and its contents transferred to a mechanically stirred evaporator, where n-hexane * 'was removed with nitrogen recycling heated to 70 ° C.

MM

la. 100 kg of prepolymer containing 40 g of polyethylene per mole of titanium were obtained.

; · Ι · ι c) Preparation of Copolymer from Ethylene and 1-Hexene 30;

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; * The step was carried out in the gaseous phase polymerization reactor 1 shown in Fig. 1, consisting essentially of: a horizontal cylinder 75 cm in diameter and 6 m above which was a separation chamber 3 fitted to the lower part of the invention 4 and recycling line * '* 5, which connected the upper part of the separation chamber to the lower part of the reactor located under the fluidization screen 10 112242, the recycling line 5 being provided with heat exchanger 6, compressor 7 and ethylene 8, 1-hexene 9 and hydrogen 10 feed lines. The reactor also had a feed line for prepolymer 11 and a line 12 for removal of the copolymer.

The reactor contained a polymer mat made of a fluidized bed mattress of 2.5 m height, through which was passed a reaction gas mixture having an upward velocity of 45 cm / sec, an absolute pressure of 1.7 MPa and a temperature measured at 10 outlet of 80 ° C.

The reaction gas mixture comprised, by volume, 15% ethylene, 2.6% 1-hexene, 3.5% hydrogen and 78.9% nitrogen.

A previously prepared prepolymer was fed to the reactor at a rate of 650 g / h. It was fed separately with triethylaluminium at a rate of 40 mmol / h. Further, it was fed with chloroform at a rate of 0.7 mmol per hour. The molar ratio of chloroform to titanium introduced into the reactor was thus 0.043.

Under these conditions, the ethylene polymer of 0.918 density, 12 ppm titanium content, MI2, 1.3 g / 10 cm -1 · -1 minutes and containing approximately 10% by weight of 1-hexene was removed at a rate of 62 kg / h at 20 agglomerates. The catalyst activity was 310 g of polymer thi ·; per millimole of mole per hour of reaction and 0.1 MPa ethylene * * * * ·; · 25 (g / mM / h / 0.1 MPa).

Example 2 (Comparison) Preparation of a copolymer of ethylene and 1-hexene

The step was carried out exactly as in Example 1 ... (c) except that chloroform was not used during the co-polymerization reaction. Under these conditions, the catalyst activity was 240 g / mM / h / 0.1 MPa.

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Ib · Example 3 a) Preparation of the catalyst

The step was carried out exactly as in Example 1, except that 48 moles of dimethylformamide were added to the mixture obtained at the end of the preparation and stirred at 80 for 112242 ° C. The mixture thus obtained was then kept stirred at 80 ° C for 2 hours. At the end of this period, the mixture was cooled to 20 ° C and the catalyst was then suspended in n-hexane.

B) Preparation of the prepolymer

The step was carried out exactly as in Example 1 except that 3 mol of tri-n-octylaluminium and the catalyst prepared above were used in an amount of 2.5 mol titanium.

C) Preparation of copolymer from ethylene and 1-butene

The step was carried out exactly as in Example 1 except that a gas phase polymerization reactor of 90 cm diameter, a fluid bed of 380 kg of polymer and a reaction mixture flow rate of 15 upwards at 37 cm / s, absolute pressure of 1.9 MPa, were used. 94 ° C and composition 7.4% ethylene, 2.3% 1-butene, 29.4% hydrogen and 20.9% nitrogen.

A previously prepared prepolymer was charged to the reactor at a rate of 1200 g / h. In addition, chloroform was continuously fed at doses such that the molar ratio of chloroform to titanium introduced into the reactor varied as shown in Table 1.

.,; * Table 1 _ 2 5 Ti residue; · Chloroform: copoly- Copoly- Catalyst: '· ** in titanium mer

Tissue molar ratio (ppm) 1 pe (kg / h) (g / mM / h / 0, IMPa) A (vert) 0 22 82 58 • »30 B 0.043 17 80 77 C 0.068 17 80 77 • · i ·· D 0.091 17 80 74 E (vert) 0.176 25 64 41 F (vert) 0.281 40 57 26 '• "I 35"' 'ppm: ppm.

, 112242 12

The analysis of the experiments in Table 1 shows that in the experiments B, C and D the catalyst activity was significantly increased (about + 30%) compared to the experiment A (control) which did not use chloroform. Catalyst activity decreased 5 dramatically in E (control) and F (control). Figure 2 shows a plot of catalyst activity (in g / mM / h / 0.1 MPa) as a function of the chloroform: titanium to molar ratio in Experiments A through F.

Example 4 10 a) Preparation of catalyst

The step was carried out exactly as in Example 3.

b) Preparation of the prepolymer

The step was carried out exactly as in Example 15, except that tri-n-octylaluminium was used in 4 mol.

(c) Production of polyethylene

The step was carried out exactly as in Example 3 except that a reaction gas mixture of 38.9% by volume ethylene, 42.8% hydrogen and 18.3% nitrogen was used.

| The reactor was fed with a pre-prepared pre-poly mer at a rate of 960 g / h. In addition, it was fed continuously with chloroform at doses such that the molar ratio of chloroform to titanium introduced into the reactor varied as shown in Table 2.

«Il · •» 13 1 12242

Table 2 Ti residue

Chloroform: copoly- Copoly- Catalyst-titanium monomer inactivity of the polymer 5 Experiment molar ratio (ppm) 1 speed (kg / h) (g / mM / h / 0, IMPa) G (vert) 0 15 86 78 H 0.031 11 100 126 I 0.052 10 120 143 J 0.085 9 128 154 10 xppm: parts per million by weight.

Analysis of the experiments shown in Table 2 shows that the catalyst activity in Experiments H, I and J increased significantly (from 61 to 97%) compared to Experiment G (ver-15 tailing), in which no chloroform was used.

Example 5 a) Preparation of a catalyst

The step was carried out exactly as in Example 1 (a).

B) Preparation of the prepolymer 500 l of n-hexane, 2.5 mol of tri-n-octylaluminium: · 'and an amount of the previously prepared catalyst containing 2.5 mol of titanium were introduced into 1.5 m3 of stainless steel. “A steel reactor maintained under a nitrogen atmosphere and having a rotary agitator at 150 rpm and heated to 70 ° C. Hydrogen was then introduced to give a partial pressure of 0.1 MPa and ethylene at a constant flow rate of 15 kg / h for 5 hours 50 minutes. This. after a period of time, the reactor was degassed and its contents transferred to a mechanically stirred evaporator in which ** · n-hexane was removed by a nitrogen cycle heated to 70 ° C. 87.5 kg of a prepolymer was obtained containing 35 g of polyethylene per mole of titanium.

(c) Preparation of copolymer from ethylene and 1-hexene

The step was carried out in a similar reactor as in Example 1 (c). The reactor contained a polymer matrix formed of a fluidized bed mattress of 2.5 m in height, passing a reaction gas mixture having an upward velocity of 45 cm / s, an absolute pressure of 1.7 MPa and a temperature measured at the outlet of the separation chamber at 80 ° C.

The reaction gas mixture comprised 37% by volume of ethylene, 7.0% of 1-hexene, 6.3% of hydrogen and 49.7% of nitrogen.

A previously prepared prepolymer was fed to the reactor at a rate of 350 g / h. It was fed separately with triethylaluminum at a rate of 20 mmol / h. Further, it was fed with chloroform at a rate of 0.5 mmol per hour. The molar ratio of chloroform to titanium introduced into the reactor was thus 0.05.

Under these conditions, an ethylene polymer free of agglomerate having a density of 0.9175, a titanium content of 6 ppm, a melt index of M1, 0.8 g / 10 for 20 minutes and containing approximately 10% by weight of 1-hexene was removed at 80 kg / h. The catalyst activity was 450 g of polymer thi; Per millimole of mole per hour of reaction and 0.1 MPa ethylene pressure (g / mM / h / 0.1 MPa).

Example 6 (Reference) *. ** 2 5 Preparation of Copolymer from Ethylene and 1-Hexene · 'The step was carried out exactly as in Example 5 (c) except that chloroform was not used during the copolymerization reaction. Under these conditions, the catalyst activity was 240 g / mM / h / 0.1 MPa. The resulting polymer had a index index of M122.16 of 0.55 g / 10 minutes and a soluble material content of 2.9%.

i »• '·. Example 7 • · ·: a) Preparation of a catalyst

The fluidized beds in the reactor and the silicon microspheres, which 'II! 35 Joseph Crosfield and Sons (United Kingdom) sells under the trade name ··· '"ES 70" r, was subjected to heat treatment at 870-112242 for 15 hours at 15 ° C under nitrogen. At the end of this period, the silicon powder thus obtained was cooled to ambient temperature (20 ° C) and kept under a nitrogen atmosphere.

In a 240 L stainless steel reactor with a stirrer rotating at 5 rpm 166 rpm, 20 kg of previously prepared silicon powder and n-hexane were introduced at ambient temperature to give 110 l of slurry followed by 50 mol of 16 mol of hexamethyldisilazane. The suspension thus obtained was kept under stirring for 4 hours to 10 hours at 80 ° C. It contained a solid which was washed five times with 130 l of 50 ° C n-hexane each.

30 mol of dibutylmagnesium were then introduced into the reactor at 50 ° C for 2 hours. The suspension thus obtained was kept stirred at 50 ° C for 1 hour. It contained 15 solids containing 1.5 mmol magnesium per 1 g.

A reactor containing the solid product in a n-hexane suspension heated at 50 ° C was charged with 60 mol of tertiary butyl chloride over 2 hours. At the end of this period, the 20 suspensions thus obtained were stirred for 1 hour at 50 ° C. It contained a solid product which was washed three times with • 1 · 130 N at 50 ° C n-hexane.

To the reactor kept at 50 ° C was introduced 6 mol of tri -: · ethyl orthoacetate. The suspension thus obtained was kept under stirring for 1 hour at 50 ° C.

12 mol of trimethylaluminum was then introduced into the reactor at 50 ° C. The suspension thus obtained was kept for 2 hours at 80 ° C.

... To the reactor cooled to 50 ° C was introduced 3 mol of titanium tetra-n-butoxide and 3 mol of titanium tetrachloride. The suspension thus obtained was kept under stirring for 2 hours at 80 ° C, then cooled at 20 ° C. It is-”*; contained a crystalline catalyst which was washed five times each. 130 l of n-hexane at 20 ° C. The catalyst contained 1 g * »35 silicon, 1.5 mmol magnesium, 3 mmol chlorine and 0.3 mmol thi ···”.

16 11224 / b) Preparation of prepolymer 450 l of n-hexane, 15 g of antistatic composition "ASA 3" r sold by Shell (The Netherlands) containing 0.55% by weight of chromium and calcium, previously prepared catalyst-5, containing 2 mol of titanium and 8 mol of tri-n-octylaluminium was introduced into a 1 m3 stainless steel reactor equipped with a stirrer rotating at 140 rpm. Hydrogen was introduced into the catalyst suspension heated to 70 ° C to give a partial pressure of 10 MPa and ethylene at a constant flow rate of 15 kg / h for 5 hours 20 minutes. At the end of this period, the thus obtained prepolymer suspension was transferred to a mechanically stirred evaporator, in which the n-hexane was removed by nitrogen recycling heated to 70 ° C. 80 kg of prepoly-15 mer having an average diameter of 90 microns and a solid density of 0.45 g / cm 3 were obtained.

c) Preparation of a copolymer from ethylene and 1-hexene

The step was carried out in a similar reactor as in Example 1 except using the prepolymer prepared above and a reaction gas mixture consisting of 30% by volume ethylene, 4.2% 1-hexene, 6% hydrogen and *, 59.8% nitrogen.

··· Previously prepared prepolymer was fed to the reactor at a rate of 160 g / h. It was fed separately with triethylaluminum at a rate of 22.6 mmol / h. Further "V. ' it was fed with chloroform at such a rate that the molar ratio of chloroform to titanium introduced into the reactor was thus 0.08.

Under these conditions, at a rate of 85 kg / h, the ethylene polymer free of agglomerate having a density of 0.917, a melt index M112 of 1.0 g / 10 minutes and an average diameter of 920 microns were removed. The catalyst activity was 1,160 g of polymer * per mole of titanium per hour of reaction and 0.1 * · *! 35 MPa at ethylene pressure (g / mM / h / 0.1 MPa).

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Example 8 (Comparison)

Preparation of copolymer from ethylene and 1-hexene

The step was carried out exactly as in Example 7 except that chloroform was not used. Under these conditions, the catalyst activity was 8200 g / mM / h / 0.1 MPa. The copolymer had a density of 0.919, a melt index MI2 of 1.6 g / 10 minutes and an average diameter of 790 microns.

Example 9 (a) Preparation of Magnesium Chloride Support 10.1 L (40 mol) of diisamoyl ether (DIAE) was introduced at ambient temperature (20 ° C) and under nitrogen atmosphere into a 300 L stainless steel reactor with 150 rpm rotary mixer containing 80 mole of dibutylmagnesium as a solution in 133 l of n-15 hexane. The reactor was maintained at 30 ° C. 19.3 L (176 mol) of tert-butyl chloride was introduced therein in 12 hours. The mixture was then stirred for 2 hours at 30 ° C. The resulting solid was washed 7 times, each with 130 liters of 30 ° C n-hexane. This gave 80 mol of magnesium chloride as spherical 20 particles having an average diameter of 26 microns, a particle size distribution of Dm / Dn 1.5 and a DIAE / Mg molar ratio of "0.103 and a Cl / Mg molar ratio of 2.17.

! ' b) Preparation of the catalyst, 110 L of n-hexane containing 70 mol of previously prepared magnesium chloride was introduced under a nitrogen atmosphere into a 300 ··· l stainless steel reactor equipped with a 160 rpm rotary stirring system. The reactor was heated to 70 ° C for 1 hour. The solid thus obtained was washed twice each time with 130 l of 70 ° C n-hexane, and then twice, each time with 13 0 l 25 ° C n-hexane. At a reaction temperature of 25 ° C, 18.9 L of n-hexane containing 35 mol of ethanol and 7 mol of triethyl orthoacetate were introduced. The reactor was then kept stirred at 25 ° C for 1 hour. Spending this time - '!!! The resulting solid product was washed 4 times, each time with 25130 L of 25 ° C n-hexane, and the volume of the suspension was then returned to 110 L by removing a portion of the n-hexane. The reactor was then heated to 50 ° C and 80 l of n-hexane containing 70 mol of triethylaluminium were introduced over an hour. After stirring continuously for 5 hours and at 50 ° C, the resulting solid product was washed 3 times with 130 l of 50 ° C n-hexane, and 6 times with 130 l of 25 ° C each time. hexane and the suspension volume was brought back to 100 L by removing some of the n-hexane. 32 L of n-hexane containing a mixture of 10 mol of titanium tetrachloride and 7 mol of titanium tetra-n-propoxide was then introduced into the reactor for 1 hour. The reactor was then kept stirred at 80 ° C for 1 hour. After this time, the resulting solid was washed twice with 130 l of 80 ° C n-hexane each, then twice with 130 l of 50 ° C n-hexane each time, and 5 times with 130 l of 25 ° C n-hexane. respectively. A catalyst was then obtained which had the following properties: - titanium / magnesium molar ratio 0.019 - aluminum / magnesium molar ratio 0.007 20 - trivalent titanium / magnesium molar ratio 0.45 - chlorine / magnesium molar ratio 2.25: * - DIAE / magnesium molar ratio 0 c) Preparation of a prepolymer in a 1 m 3 stainless steel reactor with *: * 2 5 jacket and stirrer rotating at 14 0 rpm, 450 l of n-hexane, 15 g of anti-; '. static composition "ASA-3" R sold by Shell (The Netherlands) containing 0.55% by weight of chromium and calcium, a previously prepared catalyst in an amount corresponding to 3 mol of titanium 30 and finally 4.8 mol of tri- -oktyylialumiinia. The catalyst suspension thus prepared was heated to 70 ° C and then hydrogen was introduced thereto to give a partial pressure of 0.1 MPa and a mixture of 70% by volume of ethylene and 30% by volume within 6 hours. hydrogen at a constant speed of 20 kg / h. Prepolymer * !!! At the end of 35 digestion reactions, the resulting prepolymer suspension was cooled to 60 ° C. 120 kg of a prepolymer, 19124242 having excellent dry flow properties, a weight average diameter of 80 micrometers and a solid density of 0.49 g / ml were recovered.

d) Copolymerization of Ethylene and 1-Hexene 5 100 kg of anhydrous polyethylene powder were introduced under a nitrogen atmosphere into a 75 cm diameter reactor containing a 75 cm thick fluidized bed as a polymer charge from the previous reaction. Then, a gas mixture heated to 80 ° C containing hydrogen, ethylene, 1-hexene and nitrogen was introduced and transported upwards at a rate of 44 cm / sec. The partial pressures of the components of this mixture were: hydrogen 0.072 MPa ethylene 0.425 MPa 1-hexene 0.064 MPa 15 nitrogen 1.140 MPa

The prepolymer obtained above was then introduced into this reactor at 120 g / h and triethylaluminum at 22 mmol / h. Chloroform was continuously introduced at a rate of 0.24 mmol per hour. As a result, the molar ratio of chloroform to titanium introduced into the re-20 actor was 0.08. The catalyst activity was 1070 g / mM / h / 0.1 MPa and when the polymerization conditions were stabilized, at 70 kg / h 'a copolymer powder was obtained which had the following characteristics: - solid density: 0.37 g / cm 3 - melt index MI2, i6: 0.9 g / 10 minutes j1 - flow parameter n: 1.5 - density: 0.918 - weight average diameter: 700 microns - fines content less than 125 microns * 30 nia: 0.1% by weight - titanium content: 2 ppm • '· · molecular weight distribution width: 3.9 i * 20 1 12242

Example 10

Copolymerization of ethylene and 1-hexene

The step was carried out exactly as in Example 9 (d) except that chloroform was not used during the copolymerization reaction. Under these conditions, the catalyst activity was 720 g / mM / h / 0.1 MPa.

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Claims (11)

112242 21 Use of a halogenated hydrocarbon compound to increase the catalyst activity in the continuous (co) polymerization of one or more olefins, in the presence of a Ziegler-Natta-type titanium-based catalyst which does not contain substantially any other transition metals, and wherein: the amount of halogenated hydrocarbon used is such that the molar ratio of the amount of halogenated hydrocarbon compound to titanium introduced into the polymerization medium is greater than 0.001 and less than 0.15. Use according to claim 1, characterized in that the molar ratio of the amount of halogenated hydrocarbon compound 15 to the amount of titanium introduced into the polymerization medium is greater than 0.01 and less than 0.1. Use according to claim 1 or 2, characterized in that the molar ratio of the amount of halogenated hydrocarbon compound to the amount of titanium introduced into the polymerization medium is greater than 0.03 and less than 0.095. Use according to any one of claims 1 to 3, characterized in that the halogenated hydrocarbon compound is continuously introduced into the polymerization medium. Use according to any one of claims 1 to 4, characterized in that the (co) polymerization is carried out in the gas phase. • tl » Use according to any one of claims 1 to 5, characterized in that the halogenated hydrocarbon ... is provided in an amount such that the molar ratio of the amount of halogenated hydrocarbon compound to the amount of titanium produced in the polymerization medium is in the range 0.031 to 0.091. Use according to any one of claims 1 to 6, characterized in that the organometallic cocatalyst. is introduced in an amount such that the molar ratio of the amount of halogenated hydrocarbon to the amount of organometallic cocatalyst introduced into the polymerization medium is from 0.001 to 0.5. 22 11224k Use according to any one of claims 1 to 7, characterized in that the halogenated hydrocarbon compound is a mono- or polyhalogenated saturated hydrocarbon. Use according to claim 8, characterized in that the halogenated hydrocarbon is selected from methylene chloride, chloroform, carbon tetrachloride, trichloro-1,1,1-ethane and dichloro-1,2-ethane. Use according to any one of claims 1 to 9, characterized in that the catalyst contains substantially atoms of titanium, halogen and magnesium and optionally non-fusible oxide. Use according to any one of claims 1 to 10, characterized in that the catalyst is prepared by a process comprising: (1) contacting (a) a dialkylmagnesium metal reaction between a magnesium metal, a halogenated hydrocarbon and at least one tetravalent titanium compound; and optionally contacting a trialkylaluminum, (b) a halogenated hydrocarbon, and (c) a tetravalent titanium compound, (3) or a magnesium chloride support, (a) an organometallic compound suitable for reducing the titanium compound, and (a). b) with a tetravalent titanium compound. I I I 23 1 12242