JPH0420001B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for polymerizing ethylene. In particular, the present invention relates to a method of adding a novel deactivator to the polymerization reaction mixture to deactivate the catalyst in the high temperature, high pressure polymerization of ethylene using a Ziegler type catalyst. A method is known in which ethylene is polymerized at high temperature and pressure in the presence of a Ziegler type catalyst obtained from a titanium compound and an organoaluminium compound. For example, JP-A-46-5640 and JP-B-48-6183 describe a method of polymerizing ethylene at high temperature and pressure in the presence of a catalyst obtained from a titanium halide and an organoaluminum compound. Also,
JP-A-52-103485 and JP-A No. 56-18607 disclose a method of polymerizing ethylene at high temperature and high pressure in the presence of a catalyst obtained from a titanium compound supported on a magnesium compound and an organoaluminium compound. ing. In the industrial high-temperature, high-pressure polymerization method of ethylene, ethylene is polymerized using a tubular reactor or a tank reactor, and then the polymerization reaction mixture is introduced into a separator maintained at a lower pressure than the reactor to produce the product. A process is employed in which unreacted ethylene is separated from the polymer and recycled to the reactor. When the above-mentioned known high-temperature, high-pressure polymerization method for ethylene is carried out industrially, residual active catalyst is brought into the separator, resulting in the formation of unintended polymer in the separator, and in some cases. Consequently, a problem arises in that the above-mentioned catalyst is entrained in the circulating ethylene, and the ethylene polymerizes in the circulation line, clogging the line. Therefore, in high-temperature, high-pressure polymerization of ethylene using a Ziegler type catalyst, it is extremely important to deactivate the catalyst in the polymerization reaction mixture at the end of the polymerization reaction. Regarding the method of inactivating the Ziegler type catalyst used in the high-temperature, high-pressure polymerization of ethylene, only the method described in JP-A-51-111282 has been proposed. According to the method described in the above publication, the Ziegler type catalyst in the polymerization reaction mixture is deactivated by adding an alkali metal salt or alkaline earth metal salt of a fatty acid, typified by calcium stearate, as a deactivator at the end of the polymerization reaction. It is then inactivated. In the present invention, ethylene or a mixture of ethylene and an α-olefin having 3 or more carbon atoms is heated at a pressure of 200 kg/cm ² or more and a temperature of 125°C or more in the presence of a catalyst obtained from a transition metal derivative and an organoaluminum compound. This is an ethylene polymerization method characterized by using an aluminum salt of a carboxylic acid as a deactivator when polymerizing with ethylene and adding a deactivator to the polymerization reaction mixture to deactivate the catalyst. Since the deactivator used in the present invention efficiently deactivates the catalyst in the polymerization reaction mixture, it is possible to prevent undesirable ethylene polymerization after the aforementioned polymerization reaction step. Furthermore, the deactivator used in the present invention does not mix with the ethylene that is circulated from the separator to the polymerization reactor, so it does not inhibit the ethylene polymerization reaction. The transition metal derivative in the present invention includes halogen-containing compounds of titanium, vanadium, zirconium, and chromium. Among these, halogen-containing titanium compounds are preferably used. Specific examples of halogen-containing titanium compounds include titanium trihalide, solid solutions of titanium trihalide and aluminum halide, and supported titanium compounds containing magnesium, halogen, and titanium as essential components. In addition to the above-mentioned essential components, this supported titanium compound may also contain halides, oxides, and alkoxides of calcium, aluminum, silicon, tin, zinc, etc., and may further contain electron donors such as carboxylic acid esters,
It can also contain ethers, ketones, and amines. Supported titanium compounds can be prepared by methods known per se. For example, a method of co-pulverizing magnesium chloride with a titanium halide in the presence or absence of an electron donor, a method of co-pulverizing a reaction product of an organomagnesium compound with an alkyl aluminum halide, an alkoxy aluminum halide, an alkyl silane halide or an alkoxy silane halide. Method of reacting with titanium halide, JP-A-56-55405 and JP-A-57-57, filed by the present applicant
Publication No. 83510, Publication No. 57-115408, Publication No. 57-
Publication No. 141408, Publication No. 57-145105, Publication No. 58-2305
Publication No. 149507, specification of patent application No. 149507, No. 56-
It can be prepared according to the method described in No. 158075. The organoaluminum compound has the formula R ¹ _n AlX _3- m (wherein R ¹ represents an alkyl group having 1 to 8 carbon atoms,
X represents a halogen atom, and m is 1.5 to 3. ) Compounds represented by these formulas are preferably used. Specific examples include triethylaluminum, tributylaluminum, trioctylaluminum, diethylaluminum chloride, dibutylaluminum chloride, dihexylaluminum chloride, diethylaluminum bromide, diethylaluminum iodide, ethylaluminum sesquichloride, butylaluminum sesquichloride, hexylaluminum sesquichloride. Examples include chloride, ethylaluminum sesquibromide, and ethylaluminum sesquiiodide. Among these, dialkyl aluminum halides are preferably used from the viewpoint of increasing polymerization activity. The amount of organoaluminum compound used is per gram atom of titanium in the titanium compound.
It is usually 1 to 1000 moles. Specific examples of α-olefins having 3 or more carbon atoms that can be copolymerized with ethylene include propylene, butene-1,4-methylpentene-1, and octene-1. 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 titanium compound and the organoaluminum compound can be supplied to the polymerization system individually or as a mixture in advance. Moreover, both can be pretreated with ethylene or an α-olefin having 3 or more carbon atoms in the presence or absence of an inert organic solvent, and then supplied to the polymerization system. The molecular weight of the polyethylene produced can be easily controlled by adding a molecular weight regulator, such as hydrogen, to the polymerization system. The aluminum salt of carboxylic acid has the formula ( ^R2COO )nAl(OH) _3- n (wherein ^R2 represents an alkyl group having 7 to 20 carbon atoms,
n is 1, 2 or 3. ) is used. Specific examples include aluminum monolaurate, aluminum monopalmitate, aluminum monostearate, aluminum dipalmitate, aluminum distearate, and aluminum tristearate. The amount of the deactivator to be used may be sufficient to deactivate the catalyst in the polymerization reaction mixture, but per mole of organoaluminum compound supplied to the polymerization system,
0.2 to 10 gram equivalents, especially 0.5 to 5 gram equivalents of the carboxyl group or ester group in the deactivator
Gram equivalents are preferred. There are no particular restrictions on the method of adding the quencher;
It can be added to the polymerization reaction mixture in a molten state or suspended or dissolved in an inert organic solvent. Specific examples of inert organic solvents include white spirit, hydrocarbon oil, pentane, hexane, heptane, and cyclohexane. Preferably, the quencher is added to the polymerization reaction mixture near the outlet of the reactor. Taking a tubular reactor as an example, it is preferable to add the deactivator to the polymerization reaction mixture in the vicinity of the pressure reducing valve provided between the reactor and the separator. Next, examples will be shown. Example 1 (1) Preparation of titanium compound Toluene slurry 15 of aluminum chloride 1.0Kg
at approximately 20°C, methyltriethoxysilane 1.3
Kg of toluene solution 5 was added dropwise over 50 minutes, then
The temperature was 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.
The temperature was then raised to 25°C and maintained at the same temperature for 1 hour.
The precipitated carrier was separated and washed with toluene. Titanium tetrachloride 8.3 in toluene suspension of carrier 15
was added and the two were brought into contact at 90°C for 1 hour. The obtained supported titanium compound was separated and washed with toluene. The titanium content of the supported titanium compound is 5.2
It was in weight%. (2) Polymerization In a reaction tube with a total length of about 400 m, 60% by weight of ethylene,
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 copolymerized under a pressure of 2000 Kg/cm ² . The supported titanium compound and diethylaluminium chloride were fed continuously at a rate of 56 g/h and 38 g/h, respectively, from an injection point provided at the inlet of the reaction tube. Additionally, aluminum stearate was continuously fed at a rate of 110 g/hour from an injection point located 350 m from the inlet of the reactor. The temperature inside the reaction tube was maintained at 150°C at the inlet and 250°C at the maximum temperature. The flow rate of monomer in the reaction tube is
The speed was set to 10m/sec. The polymerization reaction mixture was introduced into a separator, and unreacted monomers separated from the produced polymer were circulated and fed to the reactor. The above continuous operation was carried out for 3 hours. It was observed that the temperature inside the reaction tube decreased considerably after the injection point of the quencher. The yield of ethylene/butene-1 copolymer per gram of titanium compound fed was 24,200 grams. The density of the resulting copolymer was 0.921 g/cm ³ . Also,
No change in copolymer yield over time was observed. In the following examples, in order to clarify the effect of the quenching agent used in the present invention, the quenching agent is added from an injection point immediately after the injection point of the titanium compound and the organoaluminum compound. Except for this, the procedure was carried out in the same manner as in Example 1, and ethylene and butene-1 were copolymerized. The yield of the produced copolymer was compared with that of Example 1. Calculated according to the formula. Inactivation rate (%) = 1 - Yield of Examples 2-3/Yield of Example 1 x 100 Examples 2-3 A predetermined amount of the deactivator listed in Table 1 was added to the reaction tube as described above. Example 1 was repeated, except that The results are shown in Table 1. In Examples 1 to 3, aluminum monostearate was used after free stearic acid mixed as an impurity was purified and removed. 【table】

Claims (1)

[Claims] 1 Ethylene or ethylene and α- having 3 or more carbon atoms
A mixture with olefin is polymerized in the presence of a catalyst obtained from a transition metal derivative and an organoaluminum compound at a pressure of 200 kg/cm ² or more and a temperature of 125° C. or more, and a deactivator is added to the polymerization reaction mixture. A method for polymerizing ethylene, characterized in that an aluminum salt of carboxylic acid is used as a deactivator when deactivating a catalyst.