JPH0356561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for the polymerization of ethylene, and in particular to a process for the high pressure polymerization of ethylene using a highly active Ziegler type catalyst. Several proposals have been made regarding high-pressure polymerization of ethylene using Ziegler-type catalysts. Japanese Patent Publication No. 48-6183 describes a catalyst obtained from a trivalent titanium compound and an organoaluminum compound.
- A method is disclosed in which ethylene is pretreated in contact with an olefin and then ethylene is polymerized at high pressure in the presence of the pretreated product. According to this method, the amount of polyethylene produced per trivalent titanium compound used is small. For example, according to Example 1 of the above publication, the amount of polyethylene produced per 1 g of titanium trichloride is as small as about 8,600 g, and from the polyethylene produced. An operation to remove catalyst residue is essential. In order to increase the yield of polyethylene per catalyst used, there is also known a method of high-pressure polymerization of ethylene using a catalyst obtained from a solid catalyst component in which a titanium compound is supported on a magnesium compound and an organoaluminum compound (in particular, Publication No. 56-99209, 56
-Refer to Publication No. 161406). According to this method, the amount of polyethylene produced per solid catalyst component is considerably larger than that of the proposed method. However, in order to omit the operation of removing catalyst residue from the produced polyethylene, it is necessary to further increase the polyethylene yield per solid catalyst component. The present invention provides a high-pressure polymerization process for ethylene that yields extremely high amounts of polyethylene per solid catalyst component. That is, the present invention provides (1) aluminum halide with the formula R ¹ _n Si(OR ² ) _4-n (wherein R ¹ represents an alkyl group or phenyl group having 1 to 8 carbon atoms, and R ² represents a carbon (2) The reaction product is reacted with a silicon compound represented by the formula R ³ MgX ¹ (in which R ³ represents an alkyl group having 1 to 8 carbon atoms, and X ¹ represents a halogen atom.) A support is prepared by reacting with a Grignard compound represented by A solid catalyst component (A) of the formula R ⁴ _o AlX ² _3-o (wherein R ⁴ represents an alkyl group having 1 to 6 carbon atoms, X ² represents a halogen atom, and n is 1.5 or more and 3 in the presence of a catalyst obtained from an organoaluminum compound ( ^B ) represented by This is a method for polymerizing ethylene, which is characterized by polymerizing a mixture of ethylene and α-olefin. According to the present invention, since polyethylene can be obtained in a significantly high yield per solid catalyst component, the operation of removing catalyst residues from the produced polyethylene can be omitted. Further, according to the present invention, a linear low-density ethylene copolymer can be obtained by copolymerizing not only a high-density ethylene homopolymer but also ethylene and an α-olefin having 3 or more carbon atoms. I can do it. In the present invention, the preparation of the solid catalyst component is carried out under an inert gas atmosphere such as nitrogen or argon.
It is done. Further, it is desirable that the raw material for preparing the solid catalyst component is substantially anhydrous. Specific examples of aluminum halide in the present invention include aluminum chloride, aluminum bromide, and aluminum iodide, among which aluminum chloride is preferably used. Specific examples of silicon compounds include tetramethoxysilane, tetraethoxysilane, and tetra-n-
Propoxysilane, Tetra-n-butoxysilane, Tetra-isopentoxysilane, Tetra-n
-hexoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltri-n
-butoxysilane, methyltriisopentoxysilane, methyltri-n-hexoxysilane, methyltriisooctoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltriisopentoxysilane, n-butyltriethoxysilane, isobutyl Triethoxysilane, isopentyltriethoxysilane, isopentyltri-n-butoxysilane, dimethyldiethoxysilane, dimethyldi-n-butoxysilane,
Dimethyldiisopentoxysilane, diethyldiethoxysilane, diethyldiisopentoxysilane, di-n-butyldiethoxysilane, diisobutyldiisopentoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylisobutoxysilane, triethyliso Propoxysilane, tri-n-propylethoxysilane,
Tri-n-butylethoxysilane, triisopentylethoxysilane, phenyltriethoxysilane, phenyltriisobutoxysilane, phenyltriisopentoxysilane, diphenyldiethoxysilane, diphenyldiisopentoxysilane,
Examples include diphenyldioctoxysilane, triphenylmethoxysilane, triphenylethoxysilane, and triphenylisopentoxysilane. The proportion of aluminum halide used in the reaction is preferably 0.1 to 10 mol, particularly 0.3 to 2 mol, per mol of silicon compound. The reaction between aluminum halide and a silicon compound is usually carried out by combining both compounds in an inert organic solvent with -
This is carried out by stirring for 0.1 to 2 hours at a temperature in the range of 50 to 100°C. The reaction proceeds with exotherm, and the reaction product is obtained as a solution in an inert organic solvent. The reaction product is subjected to the reaction with the Grignard compound as the above solution. Among Grignard compounds, alkylmagnesium chlorides in which X ¹ is a chlorine atom are preferably used, and specific examples include methylmagnesium chloride, ethylmagnesium chloride,
Examples include n-butylmagnesium chloride and n-hexylmagnesium chloride. The amount of Grignard compound used is preferably 0.05 to 4 mol, especially 1 to 3 mol, per mol of aluminum halide used for the preparation of the reaction product. There is no particular restriction on the method of reacting the reaction product with the Grignard compound, but an ether solution of the Grignard compound or a mixed solvent solution of ether and an aromatic hydrocarbon is gradually added to the solution of the reaction product in an inert organic solvent. Conveniently this is done by addition or addition in the reverse order. The above ether is
A compound represented by the formula R ⁵ -O-R ⁶ (wherein R ⁵ and R ⁶ represent an alkyl group having 2 to 8 carbon atoms) is preferably used, and specific examples thereof include diethyl ether, diisopropyl Examples include ether, di-n-butyl ether, diisoamyl ether, and the like. The reaction temperature is usually -50 to 100℃, preferably -20℃
~25℃. There is no particular restriction on the reaction time, but it is usually 5 minutes or more. As the reaction progresses, a white carrier precipitates out. Although the carrier thus obtained can be used as a reaction mixture for the next treatment, it is preferable to separate the carrier in advance and wash it with an inert organic solvent before using it for the next treatment. Specific examples of titanium tetrahalide include titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide, of which titanium tetrachloride is preferably used. The amount of titanium tetrahalide used is per mole of Grignard compound used in preparing the carrier.
Usually, it is 1 to 100 moles. The solid catalyst component thus obtained is separated from the reaction mixture and washed with an inert organic solvent. The titanium content of the solid catalyst component is
It is 0.5-10% by weight. Among organoaluminum compounds, compounds in which X ² is a chlorine atom are preferably used, and specific examples thereof include dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, dihexylaluminum chloride, methylaluminum sesquichloride,
Examples include ethylaluminum sesquichloride, butylaluminum sesquichloride, and hexylaluminum sesquichloride. Particularly preferred organoaluminum compounds are diethylaluminum chloride and dibutylaluminum chloride. The amount of organoaluminum compound used is per gram atom of titanium in the solid catalyst component,
It is usually 1 to 1000 moles. Specific examples of inert organic solvents used in each step of preparing the solid catalyst component include n-hexane, n-
Examples include aliphatic hydrocarbons such as heptane, aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated products thereof. In the present invention, ethylene or a mixture of ethylene and an α-olefin having 3 or more carbon atoms is polymerized in the presence of a catalyst obtained from a solid catalyst component and an organoaluminum compound to produce an ethylene homopolymer or an ethylene copolymer. Get union. Specific examples of α-olefins having 3 or more carbon atoms include propylene, butene-1,4-methylpentene-1, octene-1, and the like. Polymerization pressure is 200Kg/ ^cm2 or more, preferably 500~
It is 3000Kg/ ^cm2 . The polymerization temperature is 125°C or higher, preferably 150-350°C. The average residence time of the monomer in the polymerization system is 2 to 600 seconds, preferably 10 to 150 seconds.
Seconds. As the polymerization apparatus, a tubular reactor or a tank reactor can be used. The solid catalyst component and the organoaluminum compound can be supplied to the polymerization system individually or in a premixed manner. The molecular weight of the polyethylene produced can be easily controlled by adding a molecular weight regulator, such as hydrogen, to the polymerization system. Next, examples will be shown. In the examples, "polymerization activity" means polyethylene yield (g) per gram of solid catalyst component used, and "MI" means ASTM
Melt index of polyethylene measured at 190° C. under a load of 2.16 Kg according to D 1238. Example 1 (1) Preparation of solid catalyst component Toluene slurry of 1.0 kg of aluminum chloride
15, at about 20 °C, methyltoluethoxysilane
Drop 1.3Kg of toluene solution 5 over 50 minutes,
The temperature was then raised to 30°C and maintained at the same temperature for 2.5 hours. The reaction mixture was cooled to -10°C, and a solution of 1.57 kg of n-butylmagnesium chloride in diisoamyl ether 10 was added dropwise to the reaction mixture over 1.7 hours, and then the temperature was raised to 25°C and maintained at the same temperature for 1 hour. The precipitated carrier was separated and washed with toluene. Titanium tetrachloride in toluene suspension of carrier 15
8.3 was added and the two were brought into contact at 90°C for 1 hour. The obtained solid catalyst component was separated and washed with toluene. The titanium content of the solid catalyst component is
It was 5.2% by weight. (2) Polymerization In a reaction tube with a total length of about 400 m, 60% by weight of ethylene,
By continuously supplying a monomer consisting of 40% by weight of 1-butene and 0.2 mol% of hydrogen to the monomer, ethylene and 1-butene were added under a pressure of 2000 kg/ ^cm2 .
Copolymerized with butene. Solid catalyst component and diethylaluminium chloride at 56 g/hour and 38 g/hour, respectively.
was fed continuously from an injection point located at the inlet of the reaction tube. The temperature inside the reaction tube was maintained at 105°C at the inlet and 200°C at the maximum temperature. The flow rate and average residence time of the monomer in the reaction tube were 10 m/sec and about 40 seconds, respectively. The above continuous operation was carried out for 3 hours. MI3.2,
An ethylene/1-butene copolymer with a density of 0.922 g/cm ³ was obtained with a polymerization activity of 24,000. Examples 2 and 3 Example 1 was repeated except that 1.52 Kg of tetraethoxysilane (Example 2) or 1.75 Kg of phenyltriethoxysilane (Example 3) was used instead of methyltriethoxysilane. The results are shown in Table 1. 【table】

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the ethylene polymerization method of the present invention and the preparation process of a solid catalyst component used in the polymerization.

Claims (1)

[Claims] 1 (1) Aluminum halide is represented by the formula R ¹ _n Si(OR ² ) _4-n (wherein R ¹ represents an alkyl group or phenyl group having 1 to 8 carbon atoms, and R ² is represents an alkyl group having 1 to 8 carbon atoms, and m is 0, 1, ² or ³ . ³ represents an alkyl group having 1 to 8 carbon atoms, and X ¹ represents a halogen atom.) A support is prepared by reacting with a Grignard compound represented by The obtained solid catalyst component (A) has the formula R ⁴ _o AlX ² _3-o (wherein R ⁴ represents an alkyl group having 1 to 6 carbon atoms, X ² represents a halogen atom, and n is 1.5 or more and ethylene or ethylene and an organoaluminum compound (B) having a carbon number of less than 3, under a pressure of 200 kg/cm ² or more and at a temperature of 125°C or more. A method for polymerizing ethylene, which comprises polymerizing a mixture with the above α-olefin.