FR2583050A1 - PROCESS FOR THE POLYMERIZATION OF ETHYLENE - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR POLYMERIZING ETHYLENE. THIS PROCESS CONSISTS OF POLYMERIZING ETHYLENE OR A MIXTURE OF ETHYLENE AND AN A-OLEFINE HAVING AT LEAST 3ATOMS OF CARBON AT A TEMPERATURE NOT LESS THAN 125C UNDER A PRESSURE NOT LESS THAN 24.5 MPA IN THE PRESENCE OF A CATALYST OBTAINED FROM A SOLID CATALYTIC COMPONENT CONSISTING OF MAGNESIUM, HALOGEN, TITANIUM AND VANADIUM AS ESSENTIAL INGREDIENTS, IN WHICH THE ATOMIC RATIO OF VANADIUM TO TITANIUM IS 0.1 TO 1, AND AN ORGANIC COMPOUND OF ALUMINUM .

Description

The present invention relates to a process for polymerizing ethylene at high temperature and under high pressure
A process is known in which ethylene or a mixture of ethylene and a d-olefin is polymerized at an elevated temperature under high pressure, in the presence of a catalyst prepared from a solid catalytic component. containing magnesium, halogen and titanium as essential ingredients and an organic aluminum compound such as trialkylaluminum or dialkylaluminum chloride. Furthermore, a process is known in which vanadium is used as an essential ingredient in place of titanium in the aforementioned solid catalyst component.

 The polymers obtained by these methods have a narrow molecular weight distribution and are not preferred from the viewpoint of processability. The molecular weight distribution is considered to be broadened by modifying the polymerization process or the polymerization conditions. However, this modification is very difficult in the high temperature and high pressure polymerization process. In addition, when the solid catalytic component containing vanadium is used, the polymerization activity is much lower than the polymerization activity achieved by the solid catalytic component containing titanium.

 The main object of the present invention is to provide a process for the polymerization of ethylene, in which an ethylene polymer having a broad molecular weight distribution and good processability can be obtained with high productivity.

 According to the present invention, there is provided a process for the polymerization of ethylene, which consists in polymerizing ethylene or a mixture of ethylene and an ok-olefin having at least 3 carbon atoms at a temperature not lower at 1250C under a pressure of not less than 24.5 MPa (250 Kg / cm2) in the presence of a catalyst obtained from a solid catalytic component comprising magnesium, halogen, titanium and vanadium as essential ingredients, in which the atomic ratio of vanadium to titanium is in the range of 0.1 to 1, and an organic aluminum compound.

 The solid catalyst component used in the present invention is characterized as containing magnesium, halogen, titanium and vanadium as essential ingredients.

 The solid catalyst component can be obtained by placing a solid material containing magnesium in contact with a titanium compound and a vanadium compound.

 As examples of solid material containing magnesium, there may be mentioned a magnesium halide, a hydroxy-magnesium halide, magnesium oxide, dihydroxymagnesium, a dialkoxy-magnesium and a product obtained by treating magnesium hydroxide, a dialcoxymagnesium or a magnesium carboxylate with a halogenated compound. As another example, mention may be made of a product obtained by treating an organic magnesium compound such as an alkylmagnesium halide or a dialkylmagnesium, or its complex such as a dialkylmagnesium / trialkylmagnesium complex, with a lodified compound.

 Mention may be made, as halogenated compound, of an aluminum halide, a silicon halide, an alkoxysilane halide, an alkylsilane halide, an alkylaluminum halide, a tin halide, a titanium tetrahalide and a reaction product. an aluminum halide or a tin halide with an alkylsilane alcoholate or an arylsilane alcoholate.

 As titanium compound, there may be mentioned TiXm (ORl) 4 m where X represents a halogen atom, R1 represents an alkyl group having from 1 to 6 carbon atoms and m is a number from 0 to 4, and Rl TiX4- where R2 represents an alkyl group having from 4 to 7 carbon atoms, X represents a halogen atom and t is a number from 1 to 4.

 As vanadium compound, there may be mentioned a vanadium trihalide, a vanadium tetrahalide, a vanadium oxidihalide and a vanadium oxytrihalide.

 In the solid catalytic component obtained by placing the solid material containing magnesium in contact with the titanium compound and the vanadium compound, the titanium compound and the vanadium compound are used in amounts such that the atomic ratio of vanadium to titanium is 0.1 to 1, preferably 0.3 to O, S. If this atomic ratio is less than 0.1, the molecular weight distribution of the ethylene polymer obtained cannot be widened to the desired extent, and even if this atomic ratio exceeds 1, the molecular weight distribution of the polymer obtained cannot be further enlarged, but the polymerization activity of the catalyst is reduced.

 Usually, the titanium content of the solid catalyst component is from 1 to 6% by weight and the vanadium content of the solid catalyst component is from 0.5 to 4% by weight.

 As a process for bringing the magnesium-containing solid matter into contact with the titanium compound and the vanadium compound, there may be mentioned, for example (1) a process in which the three components are co-sprayed, (2) a process in which the compound of titanium and the vanadium compound are added simultaneously or separately to a suspension in an inert organic solvent of the solid matter containing magnesium to effect contact, and (3) a process in which homogeneous solutions of the three components are brought contact to precipitate the solid catalytic component by the coprecipitation technique.

 The co-spraying process (1) can be carried out using a known sprayer such as a ball mill, a rocker mill or a column type mill. The control coupling temperature is generally from 0 to 1500C. The duration of co-spraying depends on the type of sprayer used and the quantity introduced into the sprayer, and it cannot be defined in a simple manner. However, co-spraying is generally carried out for 1 to 100 hours.

 In the contacting methods (1) and (2), the contact temperature is generally from 10 to 1500 ° C., and the contact time is usually from 1 to 120 minutes. The solid-catalyst components obtained according to the two processes (2) and (3) are collected by filtration and washed with an inert organic solvent, then they are suspended in an inert organic solvent, if necessary, and used for the reaction of polymerization.

The organic aluminum compound used in the present invention is a compound represented by the following formula R3nAlXs-n
in which R3 represents a hydrocarbon group
boné having from 1 to 8 carbon atoms, X represents
feels a halogen atom and n is a number
greater than 0 but not greater than 3.

 As specific examples of the organic aluminum compound, mention may be made of trimethylaluminium, triethylaluminium, trtisobutylaluminium, trihexylaluminium, dimethylaluminium chloride, diethylaluminium chloride, dibu tylaluminium chloride, dihexylaluminium chloride, chloride of diphenylaluminum, ethylaluminum sesquichloride, - butylaluminum sesquichloride, diethylaluminum bromide and diethylaluminum iodide.

 The amount of organic aluminum compound used is generally from 1 to 1000 moles per atom of titanium of the solid catalytic component.

 In the present invention, the organic aluminum compound can be modified by reaction with an organic carboxylic acid or a hydroxysilicon compound, if necessary. If such a modified organic aluminum compound is used, the polymerization activity of the catalyst is improved.

 As specific examples of the organic carboxylic acid, mention may be made of acetic acid, propionic acid, butyric acid, 2 ethylhexanoic acid, adipic acid, l, 10-didecanolic acid, dodecanoic acid, stearic acid and benzolic acid. As specific examples of a hydroxysilicon compound, mention may be made of methyldiphenylsilanol, triphenylsilanol, dimethylsilane diol and diphenylsilane diol. It is preferable that the modifier compound is used in an amount of 0.05 to 0.5 mole per gram atom of aluminum of the organic aluminum compound.

 In the present invention, ethylene or a mixture of ethylene and an o (-olefin having at least 3 carbon atoms) is polymerized to obtain a homopolymer or copolymer of ethylene. As particular examples of o (-olefin having at least 3 carbon atoms, mention may be made of propylene, butene-1, 4-methylpentene and octene-1.

The polymerization pressure is not less than 24.5 MPa and preferably it is from 49 to 295 MPa, and the polymerization temperature is not less than 1250C and preferably it is 150
at 3500C. The average residence time of the monomer in the polymerization system is from 2 to 600 seconds
and preferably from 10 to 150 seconds.

As a polymerization device,
use either a tubular reactor or a car
clave.

The molecular weight of polyethylene for
me can be easily adjusted by the addition of an agent
molecular weight control, such as hydro-
gene, to the polymerization system.

The present invention will be described above.
nant with reference to examples and comparative examples
following tifs. In these examples, the activity of poly
merisation indicates the quantity (kg) of the polymer of é
thylene produced per gram of titanium of the ca component
solid catalyst used for the polymer reaction
rization and IF denotes the melting index of the polymer
re of ethylene, as measured at 1900C under a load
2.16 kg according to ASTM D-1238. Q denotes the
ratio between the weight average molecular weight and
the number average molecular weight of the polymer of e
thylene, as determined by gel permeation in
using dichlorobenzene as solvent.

EXAMPLE 1
(1) Preparation of the solid catalytic component
40 liters of a suspension are added to
toluene containing 15 moles of aluminum chloride
anhydrous, 15 moles of methyltriethoxysilane, and we ef
carry out the reaction at i80C for 2 hours. We wear
then the temperature at 300C and we still perform
the reaction for 2 hours. The mixture is cooled
reaction up to -120C and we add to it
2.5 hour period, 18 liters of ether solution
diisopropyl containing 30 moles of n chloride
butylmagnesium. The temperature of the reaction mixture is brought to
30 ° C. and the reaction is carried out for 2.5 hours.

To 30 liters of the suspension in toluene containing 4.9 kg of the precipitated support is added, 150 moles of titanium tetrachloride and 0.79 mole of trichlorooxyvanadium, and the reaction is carried out at 90dC for 30 minutes. The reaction solid is collected by filtration at 900C and washed with toluene. A mineral oil is added to the catalytic component thus obtained to obtain a suspension having a solid content of 12.3 g / l. Ti contents and
V of the solid catalytic component are respectively 3.53% by weight and 2.14% by weight.

(2) Polymerization
In a reaction tube with a total length of 400 m, a mixture of monomers comprising 55% by weight of ethylene and 45% by weight of butene-1 and hydrogen in an amount of 0 is continuously introduced. 45% by volume, based on the mixture of monomers, so that the ethylene is copolymerized with butene-1 under a pressure of 196 Mpa.

 The suspension of solid catalytic component and a solution in mineral oil of diethylaluminum chloride (concentration I 1 molefl) are introduced continuously at the rate of 10 l / h and 12 l / h, respectively, into the tube. reaction from a pour point located at the entrance of the tube.

In the reaction tube, the inlet temperature is 1400C and the maximum temperature is 2500C. The flow rate of the monomer mixture in the reaction tube is adjusted to 10 m / s. A suspension in mineral oil of zinc stearate (concentration = 0.45 mol / l) is poured as a stop-reaction agent at a rate of -10 l / h from a point of pouring located at the outlet of the tube. The above continuous operation is carried out for 3 hours to give an ethylene / butene-1 copolymer.

 The values of IF, of density, of polymerization activity and of Q of the copolymer are indicated in Table 1.

EXAMPLE 2
A solid catalyst component is prepared in the same manner as in Example 1, with the difference that 150 moles of trichlorobutoxytitane are used in place of titanium tetrachloride. The Ti and V contents of the solid catalytic component are 4.05% by weight and 1.58% by weight respectively.

 The ethylene is copolymerized with butene1 using the solid catalytic component thus obtained in the same manner as described in Example 1.

The results obtained are shown in Table 1.

EXAMPLE 3
(1) Preparation of the solid catalytic component
1.9 kg of commercial anhydrous magnesium chloride and 342 g of ethyl benzoate are co-pulverized in a shaking ball mill. The product of the co-spray is incorporated into 30 liters of toluene to form a suspension. 15 liters of titanium tetrachloride are then added to the suspension and the reaction is carried out at 900C for 1 hour. The solids are collected by filtration and incorporated into 30 liters of toluene to form a suspension. 0.1 liter of trichlorooxyvanadium is then added to the suspension and the reaction is carried out at 90 ° C. for 1 hour. At the end of the reaction, the solid catalytic component is collected by filtration, washed and put into the form of a suspension in mineral oil (concentration = 15.3 g / l).

The contents of Ti and V components of the solid catalytic component are 3.60% by weight and 2.05% by weight respectively.

(2) Polymerization
The operations of Example 1 are repeated in the same manner with the difference that the suspension of solid catalyst component thus obtained is introduced at the rate of 8 liters / h, so as to carry out the copolymerization of ethylene with butene-1 . The results obtained are shown in Table I.

EXAMPLE 4
(1) Preparation of the solid catalytic component
To a suspension in n-heptane containing 3.1 kg of magnesium 2-ethylhexanoate (concentration 200 g / l), a solution in heptane of 2.4 kg of diethylaluminum chloride (concentration 7 0.5 is added). mole / l), and the reaction is carried out at room temperature to precipitate a support. The support is collected by filtration and washed, then 15 moles of titanium tetrachloride and 0.85 moles of trichloro-oxyvanadium are added to a suspension of the support in n-heptane and the reaction is continued at 900C for 1 hour. At the end of the reaction, the solid catalytic component is collected by filtration, washed and incorporated into the mineral oil to form a suspension (concentration = 12.5 g / l). The Ti and V contents of the solid catalytic component are 3.40% by weight and 2.25% by weight, respectively.

(2) Polymerization
The ethylene is copolymerized with butene-1 in the same manner as described in Example 1, with the difference that the solid catalyst component thus obtained is introduced at the rate of 12 liters / h. The results obtained are shown in Table 1.

EXAMPLE 5
(1) Preparation of the solid catalytic component
In a suspension in n-heptane containing 2.5 kg of diethoxymagnesium (concentration 0.25 kg / l), 4.5 kg of silicon tetrachloride is dropped, so that the two components react with each other. At the end of the reaction, the support formed is collected by filtration and washed. 15 liters of titanium tetrachloride and 0.1 liters of trichloro-oxyvanadium are then added to a suspension in n-heptane containing 2.1 kg of the support, and the reaction is carried out at 900C for 1 hour. reaction, the solid catalytic component formed is collected by filtration, washed and incorporated into mineral oil to form a suspension (concentration = 15.5 g / i). The Ti and V contents of the solid catalyst component are 3.65% by weight and 2.51% by weight, respectively.

(2) Polymerization
Ethylene is copolymerized with butene-1 in the same manner as described in Example 1, with the difference that the solid catalyst component thus obtained is introduced at the rate of 7.5 l / h. The results obtained are shown in Table 1.

EXAMPLE 6
Ethylene is copolymerized with butene-1 in the same manner as described in Example 1, except that triethyl aluminum chloride is used in place of diethyl aluminum chloride.

The results obtained are shown in Table 1.

TABLE 1
Example Activity of IF Density QN Polymerization
1,880 19.6 0.918 8.35
2,630 17.9 0.915 5.98
3,680 18.8 0.916 8.10
4,710 20.4 0.918 8.08
5,700 20.3 0.920 7.93
6,830 19.5 0.913 8.20
COMPARATIVE EXAMPLE 1
The operations of 1V Example 1 are repeated in the same way, except that trichloro-oxyvanadium is not used to prepare the solid catalytic component. The Ti content of the solid catalyst component is 5.02% by weight.

 The polymerization activity is 850, the IF is 18.0, the density is 0.913 and Q is 4.16.

COMPARATIVE EXAMPLE 2
The operations of Example 1 are repeated in the same way, the difference being that no titanium tetrachloride is used to prepare the solid catalytic component. The V content of the solid catalyst component is 2.82% by weight.

 The polymerization activity is 470, the IF is 19.4, the density is 0.919 and Q is 3.99.

Claims (13)

 1. Process for the polymerization of ethylene, characterized in that it consists in polymerizing ethylene or a mixture of ethylene with a fine i -ol6- having at least 3 carbon atoms at a temperature not lower than 1250C under a pressure not lower than 24.5 MPa in the presence of a catalyst obtained naked from a solid catalytic component comprising magnesium, halogen, titanium and vanadium as essential ingredients, in which the atomic ratio of vanadium to titanium is in the range of 0.1 to 1, and an organic aluminum compound.  2. Method according to claim 1 charac terized in that the solid catalytic component is obtained by placing a solid material containing magnesium in contact with a titanium compound and a vanadium compound.  3. Method according to claim 2, characterized in that the titanium compound is represented by the formula TiXm (OR) 4-m  where X represents a halogen atom, R1 represents  has an alkyl group having 1 to 6 atoms  of carbon and m is a number from O to 4, or by  the formula  Rl TiX4-l  where R represents an alkyl group having from 4 to  7 carbon atoms, X represents a halogen  and t is a number from 1 to 4.  4. Method according to claim 2, characterized in that the vanadium compound is chosen from a vanadium trihalide, a vanadium tetrahalide, a vanadium oxidihalide and a vanadium oxytrihalide.  5. Method according to any one of claims 1 to 4, characterized in that the atomic ratio of vanadium to titanium is in the range of 0.3 to 0.8.  6. Method according to any one of claims i to 5, characterized in that the solid catalytic component contains from 1 to 6% by weight of titanium and from 0.5 to 4 8 by weight of vanadium.  7. Method according to any one of claims from 2 to 6, characterized in that the solid material containing magnesium is placed in contact with the titanium compound and the vanadium compound by copulverizing these three components.  8. Method according to any one of claims 2 to 6, characterized in that the solid material containing magnesium is placed in contact with the titanium compound and the vanadium compound by simultaneous or separate addition of the titanium compound and the compound of vanadium in a suspension in an inert organic solvent of the solid matter containing magnesium.  9. Method according to any one of claims 2 to 6, characterized in that the solid material containing magnesium is placed in contact with the titanium compound and the vanadium compound by bringing homogeneous solutions of these three components into contact to make precipitate the solid catalytic component.  10. Method according to any one of claims 1 to 9, characterized in that the organic aluminum compound is represented by the following formula  R nAlX3-n  in which R3 represents a hydrocarbon group  boné having from 1 to 8 carbon atoms, X re  has a halogen atom and n is a number  greater than 0 but not greater than 3.  11. Method according to any one of claims 1 to 10, characterized in that the amount of organic aluminum compound is from 1 to 1000 moles per gram atom of titanium of the solid catalytic component.  12. Method according to claim 10 or 11, characterized in that the organic aluminum compound used is modified by reacting the organic aluminum compound with from 0.05 to 0.5 mole, per aluminum atom of the compound organic aluminum, an organic carboxylic acid or a hydroxysilicon compound.  13. Method according to any one of claims l to 12, characterized in that the polymerization is carried out at a temperature of 150 to 3500C under a pressure of 49 to 295 MPa.