JPS646206B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a method for polymerizing ethylene. Many proposals have been made regarding the method of polymerizing ethylene in the presence of a catalyst obtained from a solid catalyst component in which a titanium compound or a vanadium compound is supported on a halogen-containing magnesium compound and an organoaluminium compound. The proposed method has the advantage that the yield of polyethylene per solid catalyst component is large and that it is possible to omit the operation of removing catalyst residue from the produced polyethylene. However, since the solid catalyst component used in the proposed method contains a large amount of halogen atoms, the halogen content of the catalyst residue remaining in the produced polyethylene is high, and as a result, halogens are absorbed during molding of the resulting polyethylene. Therefore, a problem arises in that molding equipment such as extruders and molds are corroded. An object of the present invention is to provide an ethylene polymerization method that does not require an operation for removing catalyst residues from the produced polyethylene, and in which the catalyst residue remaining in the produced polyethylene has a low halogen content. The object of the present invention is to: (a) co-pulverize a product of aluminum halide and silica with a tetrahydrogen compound represented by the formula Si(OR ¹ ) ₄ [] (wherein R ¹ represents an alkyl group having 1 to 8 carbon atoms); a Grignard represented by the formula R ² MgX ¹ [ ] (wherein R ² represents an alkyl group having 1 to 8 carbon atoms, and X ¹ represents a halogen atom) to the resulting reaction product mixture. c a solid catalyst component obtained by contacting the resulting solid with titanium ^tetrahalide or _vanadium ^{oxytrihalide ;} by polymerizing ethylene in the presence of a catalyst obtained from an organoaluminum compound represented by 2 to 6 alkyl groups, X ² is a halogen atom, and n is 2 or 3. It will be achieved. According to this invention, since the halogen content of the solid catalyst component is low and the polyethylene yield per solid catalyst component is extremely high, it is possible to omit the operation of removing catalyst residue from the produced polyethylene, and furthermore, during the molding of the produced polyethylene. An excellent effect is achieved in that the molding equipment is not corroded. FIG. 1 shows the ethylene polymerization method of the present invention and the preparation process of the solid catalyst component used in the polymerization. In this invention, the solid catalyst component is prepared using substantially anhydrous compounds under an inert gas atmosphere such as nitrogen, argon, etc. In this invention, silica is generally heated at 300 to 600°C.
It is used after being dehydrated by heating to a temperature in the range of . Specific examples of aluminum halides include aluminum chloride, aluminum bromide, and aluminum iodide, among which aluminum chloride is preferably used. The mixing ratio of aluminum halide and silica is preferably 1 to 5 parts by weight of silica per 1 part by weight of aluminum halide. Co-pulverization of aluminum halide and silica is usually carried out at a temperature in the range of 0 to 100°C, preferably 0 to 50°C, for usually 0.5 to 50 hours using a known grinding machine, such as a ball mill or a vibration mill. I can do it. Specific examples of the tetraalkoxysilane represented by the formula [] include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and tetrapentoxysilane. The amount of tetraalkoxysilane used is preferably 0.25 to 4 mol, particularly about 1 mol, per mol of aluminum halide in the co-pulverized product of aluminum halide and silica. The reaction between the co-pulverized product and the tetraalkoxysilane is usually carried out by combining both in an inert organic solvent at a temperature of -50 to 100
This is carried out by stirring for 0.1 to 2 hours at a temperature in the range of .degree. The reaction proceeds with exotherm,
The reaction product is obtained as an inert organic solvent slurry. The reaction product can be subjected to the reaction with the Grignard compound as the slurry without being isolated. Among the Grignard compounds represented by the formula [], alkylmagnesium chlorides in which X ¹ is a chlorine atom are preferably used, and specific examples thereof include methylmagnesium chloride, ethylmagnesium chloride, butylmagnesium chloride, hexylmagnesium chloride, etc. It will be done. The amount of Grignard compound used is preferably from 0.05 to 4 mol, especially about 2 mol, per mol of tetraalkoxysilane used to prepare 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 slurry of the reaction product in an inert organic solvent. Conveniently, this is done by addition, and also by addition in the reverse order. As the above-mentioned ether, it is preferable to use a compound represented by the formula R ⁴ -O-R ⁵ (wherein R ⁴ and R ⁵ each represent an alkyl group having 2 to 8 carbon atoms). 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. The solid thus obtained can also be contacted as a reaction product mixture with titanium tetrahalide or vanadium oxytrihalide, but before contacting with titanium tetrahalide or vanadium oxytrihalide, it is washed with an inert organic solvent. It is preferable. Specific examples of titanium tetrahalide include titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide, of which titanium tetrachloride is preferably used. Specific examples of vanadium oxytrihalide include vanadium oxytrichloride and vanadium oxytribromide, of which vanadium oxytrichloride is preferably used. The amount of titanium tetrahalide or vanadium oxytrihalide used is 0.05 mol or more per mol of Grignard compound used in preparing the solid,
In particular, it is preferably 0.1 to 20 mol. The solid and titanium tetrahalide or vanadium oxytrihalide can be brought into contact at a temperature in the range of 20 to 200°C, preferably 60 to 140°C, usually in the presence or absence of an inert organic solvent. preferable. There are no particular restrictions on contact time, but
Usually, it is 0.5 to 3 hours. The solid catalyst component is separated from the thus obtained mixture containing the solid catalyst component by filtration, decanting, etc., and washed with an inert organic solvent. The solid catalyst component contains 0.5 to 10% by weight of titanium or vanadium. Inert organic solvents used in each step of preparing the solid catalyst component include aliphatic hydrocarbons such as hexane and heptane, alicyclic hydrocarbons such as cyclohexane and cyclopentane, and aromatic hydrocarbons such as benzene, toluene and xylene. Examples include hydrogen and halides of these hydrocarbons. In this invention, the solid catalyst component and the formula []
Ethylene is polymerized in the presence of a catalyst obtained from an organoaluminum compound represented by: Specific examples of the organoaluminum compound represented by the formula [] include triethylaluminum, tributylaluminum, tripentylaluminum, diethylaluminum chloride, dibutylaluminum chloride, dihexylaluminum chloride, diethylaluminium bromide, diethylaluminium iodide, and the like. Among these organoaluminum compounds, when the solid catalyst component contains a titanium atom, it is preferable to use trialkylaluminum in which n is 3 in the formula [], and when the solid catalyst component contains a vanadium atom, it is preferable to use a trialkylaluminum in which n is 3. It is preferable to use a dialkyl aluminum halide in which n is 2 in []. The amount of organoaluminum compound used is usually 1 to 1000 mol per gram atom of titanium or vanadium in the solid catalyst component. The polymerization reaction of ethylene can be carried out in a liquid phase or a gas phase. When carrying out a polymerization reaction in a liquid phase, for example, aliphatic hydrocarbons such as hexane and heptane, alicyclic hydrocarbons such as cyclohexane and cyclopentane, and aromatic hydrocarbons such as benzene and toluene are used as the polymerization solvent. Ru. There are no particular restrictions on the catalyst concentration in the polymerization solvent, but in general, the solid catalyst component is 0.001 to 10 milligram atoms per polymerization solvent in terms of titanium or vanadium metal, and the organoaluminum compound is 0.001 to 10 milligram atoms per polymerization solvent. ~1000 mmol. In this invention, not only ethylene is polymerized alone, but also ethylene and α-
Olefins such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, etc. can be copolymerized. In this invention, the polymerization reaction is carried out in a state substantially free of moisture and oxygen, similar to the usual polymerization reaction of ethylene using a Ziegler type catalyst. The polymerization temperature is usually 30 to 100°C, and the polymerization pressure is usually 1 to 80 kg/cm ² . In this invention, the molecular weight of the ethylene polymer obtained can be easily adjusted by adding hydrogen or a halogenated hydrocarbon, such as chloroform or 1,2-dichloroethane, to the polymerization system. Next, examples will be shown. In the following description,
"Polymerization activity" is the polymer yield (g) per 0.5 hours of polymerization time per 1 g of solid catalyst component used in the polymerization reaction, and "MI" is the yield (g) of polymer per 1 g of solid catalyst component used in the polymerization reaction.
The melt flow index was measured at 190°C under a load of 2160g. In the Examples, all solid catalyst components were prepared in a dry nitrogen gas atmosphere. Example 1 (1) Preparation of solid catalyst component Silica gel sold by Fuji Davison (Grade-952, MS-IDGel) heat-treated at 550°C for 4 hours
8 g and 2.67 g of anhydrous aluminum chloride were co-milled in a ball mill at room temperature for 20 hours. 8g of this co-pulverized product (15g as aluminum chloride)
mmol) was added to 50 ml of toluene, then 15 mmol of tetraethoxysilane was added, and the mixture was reacted for 1 hour at 25° C. with stirring. After the reaction product mixture was cooled to -10° C., 25 ml of diisoamyl ether containing 30 mmol of n-butylmagnesium chloride was added dropwise to the reaction product mixture over 60 minutes while stirring. The temperature of the reaction system is -10 to 0
It was kept within the range of ℃. After the dropwise addition was completed, the reaction was continued for 1 hour at -10°C. The solid was separated and washed with toluene. The solid was suspended in 50 ml of toluene, 150 mmol of titanium tetrachloride was added to this suspension, and the mixture was stirred at 90° C. for 1 hour.
The solid was contacted with titanium tetrachloride. The solid catalyst component was separated at the same temperature and washed with toluene and then with n-hexane. The titanium content in the solid catalyst component thus obtained was 2.99% by weight, and the chlorine content was 25.6%.
It was in weight%. (2) Polymerization After installing a glass ampoule containing a suspension of the solid catalyst component in n-hexane (1.31 mg as the solid catalyst component) into an autoclave with an internal volume of 500 ml and equipped with a stirrer, the air inside the autoclave was replaced with nitrogen. Replaced. 250 ml of hexane containing 0.55 mmol of triethylaluminum was introduced into the autoclave, and the autoclave contents were heated to 70°C. Then, ethylene was introduced until the pressure reached 10 Kg/cm ² (gauge pressure, the same applies hereinafter). Stirring of the autoclave was started, the glass ampoule was broken, and polymerization was started. During the polymerization, ethylene was continuously supplied and a pressure of 10 Kg/cm ² was maintained. The polymerization reaction was carried out for 30 minutes, unreacted ethylene was discharged, the contents of the autoclave were taken out, the polymer was separated, and it was dried under reduced pressure at 60° C. for 10 hours to obtain 47.1 g of white polyethylene. The polymerization activity was 36,000. Reference Example A catalyst was prepared in the same manner as in Example 1, except that only 15 mmol of anhydrous aluminum chloride was used instead of the co-pulverized product of silica and anhydrous aluminum chloride. The titanium content in the obtained solid catalyst component was 4.85
The chlorine content was 54.4% by weight. Solid catalyst component 4.11mg, triethylaluminum
The polymerization operation was carried out in the same manner as in Example 1, except that 1.1 mmol was used, and 92.5 g of polymer was obtained. The polymerization activity was 22,500. Examples 2 to 4 Hydrogen was introduced until the pressure reached 1 Kg/cm ² and then ethylene was introduced until the total pressure reached 11 Kg/cm ² (hydrogen partial pressure 1 Kg/cm ² , ethylene partial pressure 10 Kg/cm ² ). The same procedure as in Example 1 was carried out except that the polymerization temperature was changed. The results are shown in Table 1.

[Table] Example 5 The same procedure as in Example 2 was carried out except that the hydrogen pressure was 2 Kg/cm ² (hydrogen partial pressure 2 Kg/cm ² , ethylene partial pressure 10 Kg/cm ² ). The polymerization activity was 23700, and the MI was 0.03 g/10 min. Examples 6 and 7 The same procedure as Example 2 was carried out except that the amount of triethylaluminum used was changed. The results are shown in Table 2.

[Table] Example 8 Solid 1 prepared in the same manner as in Example 1
Take g, wash with n-hexane, and add n-hexane.
40 ml of vanadium oxychloride, 4 mmol of vanadium oxytrichloride was added to this suspension, the solid and vanadium oxychloride were brought into contact with each other at 70°C for 2 hours under stirring, and then thoroughly washed with n-hexane. Example 1
A solid catalyst component was prepared in the same manner as described above. The vanadium content in this solid catalyst component was 2.44% by weight, and the chlorine content was 25.3% by weight. Using 4.8 mg of solid catalyst component and 1 mmol of diethylaluminium monochloride, the ethylene pressure was set at 15
A polymerization reaction was carried out in the same manner as in Example 1 except that the amount was changed to Kg/cm ² , and 51.6 g of a white polymer was obtained. The polymerization activity was 10,800.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the ethylene polymerization method of the present invention.

Claims (1)

[Claims] 1a Tetraalkoxy represented by the formula Si(OR ¹ ) ₄ (wherein R ¹ represents an alkyl group having 1 to 8 carbon atoms) in a co-pulverized product of aluminum halide and silica. A Grignard compound represented by the formula R ² MgX ¹ (wherein R ² represents an alkyl group having 1 to 8 carbon atoms and X ¹ represents a halogen atom) is added to the resulting reaction product. c a solid catalyst component obtained by contacting the resulting solid with titanium tetrahalide or vanadium oxytrihalide, and d a formula R ³ nAlX ² ₃ -n (wherein R ³ has 2 to 6 carbon atoms is an alkyl group, X ² is a halogen atom, and n is 2 or 3. Polymerization method.