JPH0471924B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a process for the homopolymerization and copolymerization of ethylene at pressures of at least 300 Kg/cm ² and temperatures of at least 130° C. using extremely active Ziegler-type catalysts. There are two industrial methods for producing ethylene polymers: The first method is to polymerize ethylene by a free radical mechanism using a catalyst that generates active free radicals under polymerization conditions.
This method uses ethylene at high temperature and high pressure, typically at 140
Polymerization is carried out at ~300°C and 1000-3000 Kg/ ^cm2 or higher. Catalysts typically consist of peroxides or oxygen or combinations thereof. The second method uses a Ziegeller type catalyst at relatively low temperatures and pressures, e.g. below 250°C and below 200 kg/ ^cm2 , typically at 50-90°C and 30°C.
This is a method of ionic polymerization under conditions of Kg/cm ² or less. Ziegler type catalysts are generally classified as a to a in the periodic table.
It is composed of a group A transition metal compound and an organometallic compound such as alkyl aluminum. The first method is commonly referred to as the "high pressure method" and produces polyethylene with branches with a density of 0.935 or less, while the second method is referred to as the "low pressure method" and produces branched polyethylene with a density of 0.95 to 0.96. Polyethylene with almost no properties is produced. By the way, in addition to the first and second methods, a third method has been proposed. This is a method in which ethylene is homopolymerized or copolymerized under high pressure using an ionic polymerization catalyst such as a Ziegler type catalyst. For example, U.S. Patent No. 3,929,754 discloses that (a) at least one of titanium trichloride and titanium alkoxide;
(b) A method has been proposed in which ethylene is polymerized using a Ziegler type catalyst consisting of an alkylaluminum compound or an alkenylaluminum compound at a pressure of 1000 atmospheres or higher and a temperature of 220 to 270°C for a residence time of 150 seconds or less. The catalytic activity at this time is insufficient, with the maximum amount of polymer produced per gram of titanium atom being just under 44,000 g. Since then, many examples of high-temperature, high-pressure polymerization of ethylene using Ziegler-type catalysts have been proposed, but none of these can be said to be satisfactory in terms of catalytic activity. Particularly with metal catalysts such as Ziegler catalysts, catalyst residues in the polymer adversely affect quality. If the activity is low, there will be a large amount of catalyst residue in the polymer, which may cause coloring and deterioration of the polymer, and therefore, large-scale equipment such as a catalyst removal process or a polymer purification process will be required. Further, when a halogenated titanium compound is used as a catalyst, it is required to have high activity from the viewpoint of preventing corrosion of equipment and equipment. In order to improve these points, the present inventors conducted extensive research and found that a pressure of at least 300 Kg/cm ² , preferably 350 to 3500 Kg/cm ² , and a pressure of at least 130 Kg/cm 2
homopolymerization of ethylene or ethylene and at least one α
-We have discovered a Ziegler catalyst that is extremely active and useful in copolymerization with olefins, and have arrived at the present invention. The polyethylene obtained according to the present invention has excellent quality and can be used for film or molding. It can also be used as a blend with so-called low-pressure polyethylene, EVA, ethylene (meth)acrylic acid ester, etc. (1) Catalyst The catalyst used in the present invention is the following component A.
and component B. Component A An organoaluminum compound and/or an alkylsiloxalane derivative, among which organoaluminum compounds are particularly often used. For example, trialkylaluminum such as triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, etc., diethylaluminum chloride, di-n-propylaluminum chloride, di-n-butylaluminum chloride. , dialkylaluminum monohalides such as di-n-hexylaluminum chloride, etc.
Alkylaluminum dihalides such as ethylaluminum dichloride, n-propylaluminum dichloride, n-butylaluminum dichloride, n-hexylaluminum dichloride, ethylaluminum sesquichloride, n-
Alkylaluminum sesquichlorides such as propylaluminum sesquichloride, n-pyrylaluminum sesquichloride, and n-hexylaluminum sesquichloride are mentioned. These organoaluminum compounds may be used alone or in combination of two or more. Moreover, alkylsiloxalane derivatives can also be used as other activators. The alkylsiloxalane derivative is represented by the following formula. Here, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ are carbon numbers, 1 to 10
Although it is a saturated hydrocarbon group containing

[Formula] (R ₆ , R ₇ and R ₈ are saturated hydrocarbon groups containing 1 to 10 carbon atoms) may be used. Specific examples of the alkylsiloxalane derivatives include trimethyldimethylsiloxalane, trimethyldiethylsiloxalane, trimethyldi-n-propylsiloxalane, trimethyldi-n-butylsiloxalane, and trimethyldioctylsiloxalane. Component B A solid catalyst compound obtained by contacting the compound (a) and compound (b) shown below (a) A solid product obtained by reacting an organomagnesium compound with the halogen-containing compound () shown below. It is a thing. As the organomagnesium compound used here, any type of organomagnesium compound produced by the reaction of an organic halide and metal magnesium can be used. In particular, Grignard compounds of the general formula RMgX and general formula R ₂
Dialkylmagnesium compounds represented by Mg are preferred. Specifically, compounds in which R represents an alkyl group or an aryl group having 1 to 20 carbon atoms, such as ethylmagnesium chloride, ethylmagnesium chromide, n-propylmagnesium chloride, n-butylmagnesium chloride, tert-butylmagnesium chloride, Examples include halogenated alkylmagnesium compounds such as enylmagnesium chloride. Specific examples of the dialkylmagnesium represented by the general formula R ₂ Mg include diethylmagnesium, dipropylmagnesium, dibutylmagnesium, diphenylmagnesium, dibenzylmagnesium, and the like. These organomagnesium compounds are synthesized in the presence of an ethereal solvent such as ethyl ether, propyl ether, butyl ether, or a hydrocarbon solvent such as hexane, heptane, cyclohexane, benzene, or toluene. () General formula RaSiX _4-a (R represents an alkyl group, aryl group, or alkenyl group having 1 to 20 carbon atoms, and X represents a halogen atom. Also, a is a number expressed as 0≦a<4.) Halogenated silicon compound represented by: The greater the number of halogen atoms in the halogenated silicon compound used here, the better the results, and among them, silicon tetrachloride is most suitable. Other specific compounds include silicon tetrabromide, methylsilyl trichloride, dimethylsilyl dichloride, trimethylsilyl chloride,
Examples include ethylsilyl trichloride, diethylsilyl dichloride, triethylsilyl chloride, propylsilyl tribromide, dipropylsilyl dibromide, tripropylsilyl bromide, butylsilyl trichloride, dibutylsilyl dichloride, tributylsilyl chloride, vinylsilyl trichloride, etc. . The synthesis of the catalyst below is all carried out under an inert gas atmosphere such as nitrogen or argon. The reaction between the organomagnesium compound and () is 0 in a solvent.
Preferably it is carried out at a temperature of -100°C, preferably 0-60°C. The solvents used are aliphatic hydrocarbons such as pentane, hexane, heptane and octane, aromatic hydrocarbons such as benzene, toluene and xylene, alicyclic hydrocarbons such as cyclohexane and cyclopentane, ethyl ether, butyl ether and amyl ether. , ether compounds such as tetrahydrofurandioxane, etc., and it is particularly preferable to carry out the reaction in an ether solvent. The reaction ratio of the organomagnesium compound and the silicon halide compound is carried out in a molar ratio of 0.1 to 10.0, preferably 0.5 to 2.0. Compound (b) Halogenated titanium compound having a Ti--N bond This titanium compound is characterized in that a titanium atom is bonded to a nitrogen atom of an amino group. Therefore, it is synthesized by catalytically reacting a halogenated titanium compound and an amine compound. Note that the amine compound used here needs to contain one or more hydrogen atoms. The halogenated titanium compound is preferably titanium tetrahalide, and specific examples include titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide. Specific examples of the amine compound include methylamine, dimethylamine, ethylamine, diethylamine, ethylenediamine, aniline, diphenylamine, toluidine, and naphthylamine. The synthesis of compound (b) is preferably carried out in a solvent at a temperature of room temperature to 150°C. The reaction ratio of the halogenated titanium compound and the amine compound is 0.1 to 0.1 in molar ratio.
20.0, preferably in the range of 0.3 to 5.0. Examples of the solvent used include aliphatic hydrocarbons such as pentane, hexane, heptane, and octane, aromatic hydrocarbons such as benzene, toluene, xylene, and monochlorobenzene, and alicyclic hydrocarbons such as cyclohexane and cyclopentane. Compound (a) obtained by the above method is thoroughly washed with a solvent, dried, and then subjected to a contact reaction with compound (b).
The reaction may be carried out by directly kneading the two, or in an inert solvent such as an aliphatic hydrocarbon, an aromatic hydrocarbon, or an alicyclic hydrocarbon. After separating the reaction product from unreacted components and solvent,
Thoroughly wash and dry and use as a solid catalyst. (2) High-pressure polymerization of ethylene Polymerization can be carried out either batchwise or continuously, but continuous mode is more preferable. A continuous stirring tank reactor or a continuous tube reactor is used as the reactor. The polymerization can be carried out in a single reaction zone, but it can also be carried out in one reactor divided into several reactor zones or in a plurality of reactors connected in series or in parallel.
When a plurality of reactors are used, any combination of tank-tank type or tank-tube type may be used. In the method of polymerization using multiple reaction zones or multiple reactors, it is also possible to produce polymers with different properties by changing the temperature, pressure, and gas composition for each reaction zone. The catalyst is fed to the reactor as a finely divided dispersion in a suitable inert solvent using a high pressure pump. In polymerization under high temperature and high pressure as in the present invention, since the catalyst is injected into the high pressure part of the pump, the particle size must be small and the catalyst must have good dispersibility in the solvent. The following methods are generally used to refine the catalyst particles. That is, (a) grinding with a ball mill. (b) compounds obtained by the reaction of tetravalent titanium compounds with organoaluminum compounds and unbranched α-containing at least 6 carbon atoms in the presence of organoaluminum compounds as described in British Patent No. 979123; Prepolymerize the olefin. However, the catalyst of the present invention
Since the particle size can be controlled by changing the synthesis conditions, the operations described in (a) and (b) can be omitted. Suitable inert solvents include, for example, white spirit, hydrocarbon oils, pentane, hexane,
Mention may be made of heptane, octane, toluene, higher branched chain saturated aliphatic hydrocarbons and mixtures thereof. It is necessary to handle the catalyst dispersion under an inert gas atmosphere such as nitrogen or argon so that it does not come into contact with water or air. The catalyst may be prepared by injecting a dispersion of component (A) and component (B) into the reactor, or by injecting a dispersion of component (A) and component (B) into the reactor.
It is also possible to inject (A) and component (B) independently from separate injection tubes and mix them within the reactor. Furthermore, in the multiple reaction zone system, it may be injected all at once into the first reaction zone, or may be injected into other reaction zones dividedly. The Al/Ti atomic ratio of component (A) and component (B) during polymerization is 1 to 500, preferably 1 to 200. Furthermore, the catalyst of the present invention can not only perform homopolymerization of ethylene but also copolymerization of ethylene and other α-olefins. Specific α-olefins include propylene, butene-1, and hexene-1.
1, octene-1, 4-methyl-pentene-1, etc., and by copolymerizing with these α-olefins, polymers with a wide range of densities can be obtained. Hereinafter, the present invention will be embodied in Examples, but the present invention is not limited to the Examples. Example 1 (1) Synthesis of catalyst (A) Synthesis of organomagnesium compound 500 equipped with a stirrer, reflux condenser, and dropping funnel
Put 14 g of magnesium turnings for Grignard reagent into a ml flask, and after purging the flask with argon, charge 250 ml of di-n-butyl ether, and charge 72 ml of n-butyl chloride (1.2 molar ratio to magnesium) into the dropping funnel. Start the reaction by dropping into a flask at 50 °C.
The reaction was continued at this temperature for 2 hours to obtain a di-n-butyl ether solution of n-butylmagnesium chloride. Thereafter, the reaction solution was cooled to room temperature, and unreacted magnesium was separated. The concentration of this n-butylmagnesium chloride solution was 1.52 mol/mol. (B) Synthesis of solid product Silicon tetrachloride is added to the n-butylmagnesium chloride solution synthesized in (A) above through a dropping funnel.
The reaction was started by dropping a solution prepared by diluting 55 ml with 120 ml of toluene (molar ratio of magnesium to silicon: 1:1) into a flask at 20°C. 20
The mixture was added dropwise at ℃ for 3 hours to form a white precipitate. After further reacting at this temperature for 1 hour, the mixture was allowed to stand, and the supernatant was separated, washed with n-heptane, and dried under reduced pressure to obtain 68 g of a solid product. (C) Synthesis of titanium compound After purging a 200 ml flask equipped with a stirrer and a thermometer with argon, 30 ml of titanium tetrachloride, 80 ml of monochlorobenzene and 23.2 g of phenylamine were charged and the temperature was raised to 120°C. The reaction proceeded with the generation of hydrogen chloride gas. After maintaining this temperature for 1 hour, a brown liquid titanium compound was obtained. (D) Synthesis of solid catalyst 5 g of the solid product obtained in (B) above was charged into the liquid containing the titanium compound obtained in (C) above, and a contact reaction was carried out at 110°C for 1 hour with stirring. . After the reaction was completed, the mixture was allowed to stand still and the supernatant liquid was extracted at 100°C. Then n
- 50 ml of heptane was added, stirred at 80°C for 5 minutes, allowed to stand, and the supernatant liquid was extracted. This operation was repeated 5 times for washing. Thereafter, it was dried under reduced pressure to obtain 3.6 g of a solid catalyst. (2) Polymerization 500 ml of dehydrated n-hexane was placed in a flask with a stirrer that had been sufficiently replaced with N2, and then 2.5 g of the solid catalyst synthesized in (D) and 20 _g of triethylaluminum were added.
mmol was added to obtain a catalyst dispersion. Pour this dispersion into an autoclave equipped with a stirrer using a pump.
Ethylene was polymerized under the conditions shown in Table-1. Hydrogen was used to control the molecular weight of the resulting polymer. Note that sufficiently purified hydrogen and ethylene were used. As a result of the polymerization, 421,000 g of polymer was produced per 1 g of titanium. Examples 2 and 3 Catalyst preparation and polymerization were carried out in the same manner as in Example 1. The results are shown in Table 1.

【table】 [Brief explanation of drawings]

FIG. 1 is a flowchart to aid understanding of the present invention. This chart is a representative example of the embodiment of the present invention, and the present invention is not limited thereto.

Claims (1)

[Claims] 1. Polymerization of ethylene or copolymerization of ethylene with at least one α-olefin using a catalyst consisting of the following components A and B at a pressure of at least 300 Kg/cm ² and a temperature of at least 130°C. A method for producing an ethylene polymer, characterized in that: Component A Organoaluminum compound and/or alkylsiloxalane derivative. Component B A solid catalyst obtained by subjecting compound (a) and compound (b) shown below to a catalytic reaction. Compound (a) A solid product obtained by reacting an organomagnesium compound with the following halogen-containing compound (). () A halogenated silicon compound represented by the general formula R _a SiX _4-a where R is an alkyl group having 1 to 20 carbon atoms,
An aryl group or an alkenyl group, and X represents a halogen atom. Further, a is a number expressed as 0≦a<4. Compound (b) Halogenated titanium compound 2 having a Ti--N bond The method according to claim 1, wherein the compound (b) is a halogenated titanium compound having a bond with an amino group.