JPH0699508B2 - Method for producing polyethylene - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing polyethylene. More specifically, the present invention relates to a method for producing polyethylene by a more simplified process using a novel Ziegler-based catalyst.

Hereinafter, in the present invention, ethylene polymerization or polymer, in addition to homopolymerization or homopolymer of ethylene, shall include copolymerization or copolymer with other α-olefin copolymerizable with ethylene, A homopolymer of ethylene and a copolymer having an ethylene unit content of 50% by weight or more are collectively referred to as polyethylene.

[Prior Art] In recent years, a technology for producing polyethylene using a Ziegler-type supported catalyst has become widespread. This is mainly to improve the utilization efficiency of the catalyst, omit the catalyst removal step, and simplify the production process. Is based on what made it possible. However, the pursuit is being continued in order to further improve the utilization efficiency of the catalyst and enable a more economical polyethylene production method.

As the carrier of the Ziegler type supported catalyst, anhydrous magnesium chloride or its modified product, organomagnesium compounds such as Grignard reagent, organomagnesium compounds such as magnesium ethoxide, or compounds other than magnesium such as alumina and silica-alumina are already used. This is well known.

On the other hand, the present inventors have developed a compound having a complicated composition, which is essentially different from those carriers and is formed by a chemical reaction of a trivalent metal halide such as aluminum chloride and a divalent metal compound such as magnesium hydroxide. By using it as a carrier, we have developed a method that enhances the catalyst efficiency and makes it possible to omit the catalyst removal step. For example,
No. 57-42705 (hereinafter referred to as the above invention), in the presence of polysiloxane, a transition metal compound of Group 4a or 5a containing halogen (group A) in the above carrier and (B)
Group) a solid product prepared by simultaneously reacting at least two kinds of transition metal compounds selected from at least one kind of each group of transition metal compounds containing no halogen, and further using a solid polymer product. It was hoped that the rate would improve.

Therefore, as a result of various studies on the improvement of the above-mentioned invention, the present inventors have found that the type of compound to be present when the solid product (I) is reacted with the transition metal compound and the transition to the solid product (I). It was found that the polymer yield was remarkably improved by devising the reaction method of the metal compound, and it was proposed as Japanese Patent Application No. 59-160820 and Japanese Patent Application No. 59-267243 (both are collectively referred to as prior inventions). I applied.

The invention of the prior application aims at further increasing the polymer yield in the production of polyethylene having an excellent shape and a narrow molecular weight distribution, as compared with the conventional method.

The prior invention is a solid product obtained by reacting a trivalent metal halide with a divalent metal hydroxide, oxide, carbonate, a double salt containing these, or a hydrate of a divalent metal compound ( I) with an electron donating compound and a transition metal compound-supported final solid product obtained by reacting a transition metal compound of Group 4a or Group 5a of the periodic table with an organoaluminum compound, and ethylene is used. In the method for producing polyethylene by polymerizing a solid-state product (I), a halogen-containing transition metal compound of Group 4a or Group 5a (hereinafter halogen) is added to the solid product (I) in the presence of an electron-donating compound. A step (hereinafter referred to as step A) of reacting a contained transition metal compound, and (step B) in the presence of an electron-donating compound, a transition gold of Group 4a or Group 5a containing no halogen. A solid product (II) obtained through two steps of reacting a compound (hereinafter referred to as halogen-free transition metal compound) (hereinafter referred to as Step B) is used as a transition metal compound-supported final solid product. It is a method for producing polyethylene.

On the other hand, when ethylene is subjected to suspension polymerization in the presence of an inert solvent (hereinafter simply referred to as a solvent) using a Ziegler-type catalyst, polyethylene is separated from the slurry obtained by suspension polymerization, and the separated solvent part (Note A method for circulating the liquid residue) into the polymerization system is known from Japanese Patent Publication No. 33-8544. However, in the suspension polymerization method of ethylene by solvent circulation, even when a considerable amount of an organoaluminum compound is newly added in addition to the organoaluminum compound in the circulating solvent, the amount of the transition metal catalyst component per transition metal catalyst component is higher than that in the case of no solvent circulation. A significant decrease in the polyethylene yield (Note: so-called "polymerization activity") is unavoidable. On the other hand, by circulating the solvent in the suspension polymerization of ethylene, the consumption and recovery cost of the solvent will be drastically reduced and the production cost of polyethylene will be remarkably reduced unless other adverse results are brought about. Not only that, but the total benefit thereof is extremely large because a solvent recovery and purification device is not necessary or can be extremely simplified. The adoption of the vapor phase polymerization method of ethylene is one of the solutions. However, the gas phase polymerization method has a disadvantage in that a large amount of ethylene gas needs to be circulated for removing the polymerization heat and fluidizing.

The present inventors have continued to study a polymerization method which does not have the above-mentioned drawbacks associated with the adoption of the solvent circulation method.

As a result, it was found that, when carrying out suspension polymerization of ethylene using a catalyst in which the solid product used in the previous invention and an organoaluminum compound are combined, the polymerization activity is remarkably improved as compared with the case where the solvent is not circulated. The application was filed as Sho 57-14562 (hereinafter referred to as the "first invention").

According to the method of the above invention, the catalyst removal step can be omitted, and further, the consumption amount of solvent and the recovery cost can be significantly reduced. However, even in the method of the previous invention, a catalyst deactivation treatment step was required in order to suppress the deterioration tendency of the obtained product polyethylene during long-term use. Therefore, it is necessary to use a deactivator and a recovery device, and a more simplified manufacturing method has been desired.

[Object of the Invention] The present inventors have continued to earnestly study improvement of the above invention. As a result, surprisingly, when polyethylene is produced by suspension polymerization of ethylene using a catalyst in which the solid product (II) used in the prior invention is combined with an organoaluminum compound, stabilized polyethylene is produced. The present invention has been completed by knowing that the obtained special catalyst deactivation treatment step is unnecessary.

As is clear from the above description, an object of the present invention is to provide an improved method of the prior invention as well as an improved method of the previous invention, and specifically, polyethylene which does not require a catalyst deactivation treatment step. In order to provide the manufacturing method of. Another object is to provide a stabilized polyethylene that withstands long term use.

[Structure / Effect of Invention] The present invention has the following main structure (1) and embodiment structures (2) to (9).

(1) Solid product (I) obtained by reacting a trivalent metal halide with a divalent metal hydroxide, oxide, carbonate, double salt containing them, or a hydrate of a divalent metal compound
And electron donating compounds and groups 4a or 4
A method for producing polyethylene by polymerizing ethylene using a catalyst comprising a combination of a transition metal compound-supported final solid product obtained by reacting a transition metal compound of group 5a and an organoaluminum compound, the solid product (I) And (Step A) a step of reacting a halogen-containing Group 4a or Group 5a transition metal compound (hereinafter referred to as halogen-containing transition metal compound) in the presence of an electron-donating compound (hereinafter referred to as Step A); (Step B) of reacting a halogen-free transition metal compound of Group 4a or Group 5a (hereinafter referred to as halogen-free transition metal compound) in the presence of an electron-donating compound (hereinafter referred to as Step B) Using the fixed product (II) obtained through the two steps as the final solid product carrying a transition metal compound, continuous suspension polymerization in the presence of an inert solvent. A part of the obtained slurry containing polyethylene is continuously taken out and separated into a gaseous part, a solvent part and a polyethylene part outside the polymerization system, and the gaseous part and the solvent part are circulated to the polymerization system to form a polyethylene part. Is a method for producing polyethylene, wherein the polyethylene is directly sent to the granulation step through a drying step without going through the catalyst deactivation treatment step.

(2) As the electron-donating compound, a compound represented by the general formula ( _{1) wherein} R ₁ or R ² is the same or different residue capable of binding to silicon, and 3 ≦ n ≦ 10,000 is used. Method.

(3) As a final solid product bearing a transition metal compound, the solid product (I) is allowed to undergo the reaction of (Step A) and then the solid product (II) obtained through the reaction of (Step B). The manufacturing method as described in said (1) item which uses (1).

(4) A solid product (II) obtained as a final solid product carrying a transition metal compound by subjecting the solid product (I) to the reaction of (Step B) and then the reaction of (Step A). The manufacturing method as described in said (1) item which uses (1).

(5) The polyethylene concentration in the slurry is 50% by weight or less 5
The manufacturing method as described in the above item (1), characterized in that the content is maintained at not less than wt%.

(6) The production method according to the above item (1), wherein the slurry containing polyethylene is separated into a solvent portion and a wet cake by a centrifugal separation method, and the separated solvent portion is circulated in the polymerization system.

(7) The production method according to the above (1), wherein the wet cake is dried by air flow to separate into solvent vapor and dry powder, and the solvent in the separated solvent vapor is condensed and liquefied and circulated in the polymerization system.

(8) The production method according to the above item (1), wherein an organoaluminum compound, which is deficient in the organoaluminum compound in the solvent to be circulated, is newly supplied into the polymerization system.

(9) The production method according to the above (1), wherein hydrogen gas, which is insufficient for the hydrogen gas in the gas portion to be circulated, is newly supplied into the polymerization system.

The structure and effects of the present invention will be described below.

The trivalent metal halide used in the present invention includes aluminum trichloride (anhydrous) and iron trichloride (anhydrous).

Examples of the divalent metal compound include Mg (OH) ₂ and Ca (OH)
Hydroxides such as ₂ , Zn (OH) ₂ and Mn (OH) ₂ , MgO, CaO, Zn
O, MnO-like oxides, MgAl ₂ O ₄ , Mg ₂ SiO ₄ , Mg ₆ MnO ₆ divalent metal-containing complex oxides, MgCO ₃ , MnCO ₃ , CaCO ₃ carbonates, MgCl 2 ₂・ 6H ₂ O, SnCl ₂・ 2H ₂ O, MnCl ₂・ 4H ₂ O, KM
gCl ₃ · 6H ₂ O, a halide hydrate as NiCl ₂ · 6H ₂ O,
Hydrate of double salt containing oxide and halide such as 3MgO ・ MgCl ₂・ 4H ₂ O, double salt hydrate containing oxide of divalent metal such as 3MgO ・ 2SiO ₂・ 2H ₂ O , 3MgCO ₃・ Mg (OH) ₂・ 3H
Hydrates of double salts of carbonates and hydroxides such as ₂ O, and
An example is a hydrate of a hydroxide carbonate containing a divalent metal such as MG ₆ Al ₂ (OH) ₂ CO ₃ .4H ₂ O.

The solid product (I) is obtained by reacting a trivalent metal halide with a divalent metal compound. In order to carry out this reaction, both should be preliminarily used in a ball mill for 5 to 100 hours,
In the vibrating mill, it is preferable to perform mixing and pulverization for 1 to 10 hours, and after sufficiently mixing, heat reaction, but it is also possible to perform heat reaction while mixing and pulverizing. The ratio of the trivalent metal halide to the divalent metal compound is usually 0.01 to 20 and is preferably 0.05 to 10, as indicated by the atomic ratio of the divalent metal to the trivalent metal. The reaction temperature is generally 20 to 500 ° C, preferably 50 to 300 ° C. The reaction time is suitable for 30 minutes to 50 hours. When the reaction temperature is low, the reaction is carried out for a long time so that the unreacted trivalent metal halide does not remain, and the obtained solid product is converted into a solid product. (I).

Hereinafter, a method of causing the solid product (I), which is one embodiment of the present invention, to undergo the reaction of (step A) and then to perform the reaction of (step B) will be described.

The obtained solid product (I) is then first reacted with a halogen-containing transition metal compound in the presence of an electron-donating compound (step A).

As the electron donating compound, a compound represented by the general formula (Wherein R ₁ or R ² is the same or different residue capable of bonding to silicon, and 3 ≦ n ≦ 10,000), or a polysiloxane represented by the general formula ▲ R ¹ _m ▼ Si (OR ² ) _4- m (in the formula
R ¹ is a C _{1 to} C ₂₀ hydrocarbon group, a hydrogen atom or a halogen atom, and R ² is a C _{1 to} C ₂₀ hydrocarbon group,
Further, 0 ≦ m <4. And an oxygen-containing organic compound selected from ethers, esters, aldehydes, ketones, and carboxylic acids.

Commonly used polysiloxanes include octamethyltrisiloxane CH ₃ [Si (CH ₃ ) ₂ O] ₂ Si (CH ₃ ) ₃ and diphenyloctamethyltetrasiloxane (CH ₃ ) ₃ SiO [Si (C
H ₃ ) (C ₆ H ₅ ) O] ₂ Si (CH ₃ ) ₃ and other chain-like lower polymers,
Octaethylcyclotetrasiloxane [Si (C ₂ H ₅ ) ₂ O]
₄ , hexaphenylcyclotrisiloxane [Si (C ₆ H ₅ )
₂ O] ₃ , cyclic polymer such as dimethyl polysiloxane [Si
(CH _{3) 2} -O] n, methyl ethyl polysiloxane [Si (C
H ₃ ) (C ₂ H ₅ ) O] n, methylphenylpolysiloxane [Si
Chain polymer such as (CH ₃ ) (C ₆ H ₅ ) O] n, methyl hydrogen polysiloxane [SiH (CH ₃ ) O] n, phenyl hydrogen polysiloxane [SiH (C ₆ H ₅ ) O] n, etc. In addition to the chain alkyl hydrogen siloxane polymer and the chain aryl hydrogen siloxane polymer of chloromethyl polysiloxane [SiCl (C
H ₃ ) O] n, methylethoxypolysiloxane [Si (CH ₃ )
(C ₂ H ₅ O) O] n, chloromethoxypolysiloxane [SiCl
(CH ₃ O) O] n, methylacetoxypolysiloxane [Si
Examples thereof include chain polysiloxanes such as (CH ₃ ) (CH ₃ CO ₂ ) O] n. The polysiloxane to be used is preferably liquid and has a viscosity (25 ° C.) of 10 to 10,000 centistokes, preferably 10 to 1,000 centistokes.

As the alkoxy group-containing organosilicon compound used in the present invention, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, ethyltriethoxysilane, diethyldiethoxysilane, methyltriethoxysilane, tetrapropoxysilane, Tetra-n-butoxysilane, tetraoctoxysilane, pentyltriethoxysilane, n-octyltriethoxysilane, n-octadecyltriethoxysilane, trimethoxysilane, triethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane,
Examples thereof include trimethoxychlorosilane, dimethoxydichlorosilane and triethoxychlorosilane.

Furthermore, as the oxygen-containing organic compound, di-n-butyl ether, di (isoamyl) ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diphenyl ether, anisole, an ether such as tetrahydrofuran, ethyl acetate, butyl acetate,
Esters such as methyl propionate, methyl benzoate, ethyl benzoate, methyl toluate, ethyl toluate, methyl anisate and ethyl anisate, butyraldehyde, propionaldehyde, benzaldehyde and other aldehydes, methyl ethyl ketone, diethyl ketone, acetylacetone, acetophenone , Ketones such as benzophenone, and carboxylic acids such as acetic acid, propionic acid, and benzoic acid.

These electron-donating compounds may be used alone or in combination of two or more.

As the halogen-containing transition metal compound used in the present invention, titanium, vanadium halide, oxyhalide,
Alkoxy halides, compounds such as acetoxy halides, for example, titanium tetrachloride, titanium tetrabromide, trichloromonoisopropoxytitanium, dichlorodiisopropoxytitanium, monochlorotriisopropoxytitanium,
Examples thereof include trichloromonobutoxytitanium, dichlorodiptoxytitanium, trichloromonoethoxytitanium, vanadium tetrachloride and vanadium oxytrichloride, with titanium tetrachloride being most preferred.

The solid product (I), the electron-donating compound, and the halogen-containing transition metal compound may be mixed in any order under an inert gas such as a nitrogen atmosphere, but the mixture of the electron-donating compound and the transition metal compound may be solid. It is preferred to add the product (I). Mixing is -50 ° C to + 50 ° C, preferably -20 ° C to + 30 ° C. At that time, the presence or absence of a solvent is not limited.

The mixing ratio of the solid product (I), the electron donating compound, and the halogen-containing transition metal compound is 10 to 10,000 g, preferably 20 to 10,000 g, based on 100 g of the solid product (I).
1,000g, 10-10,000g for halogen-containing transition metal compounds,
Preferably 20 to 1,000 g, and an electron donating compound
Halogen-containing transition metal compound is 10 to 1,000 per 100 g
g, preferably 20-500 g. The reaction conditions are 40 ° C. to 300 ° C., preferably 50 ° C. to 200 ° C. for 10 minutes to 20 hours, preferably 10 minutes to 10 hours with stirring.

Upon mixing the solid product (I), the electron-donating compound, the halogen-containing transition metal compound, and their reaction,
It is not always necessary to use a solvent, but since it is preferable to carry out a uniform reaction, any or all of the above components may be dissolved or dispersed in the solvent in advance. The total amount of solvent used is about the total amount of the above three components.
10 times (weight) or less is sufficient.

Solvents used include hexane, heptane, octane,
Aliphatic hydrocarbons such as decane, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene, halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene and trichlorobenzene, carbon tetrachloride,
Chloroform, dichloroethane, trichloroethylene,
Examples thereof include halogenated hydrocarbons such as tetrachloroethylene and carbon tetrabromide.

After the reaction of the above-mentioned (Step A), the supernatant liquid is removed, and after washing with a solvent such as normal hexane, the reaction proceeds to the next reaction of the (Step B). In addition, after the reaction of the (A step), the reaction may be performed in the slurry state as it is to the next reaction of the (B step).

The solid product (II) is the above-mentioned (step A), that is, the reaction of the solid product (I), the electron-donating compound, and the halogen-containing transition metal compound, and further, the step (B) is an electron-donating compound. In the presence of a halogen-free transition metal compound.

As the electron-donating compound, the above-mentioned electron-donating compound is used, but it does not have to be the same as that used in the reaction of (Step A). In addition, when the reaction is carried out in the slurry state as it is after the reaction in the step (A) and the reaction in the next step (the step B) is carried out, an unreacted electron-donating compound is present, and therefore an electron-donating compound is newly added. Although not particularly necessary, an electron donating compound may be newly added if desired.

Examples of the halogen-free transition metal compound include titanium and vanadium alkoxides, for example, tetraethyl orthotitanate (tetraethoxytitanium), tetraisopropyl orthotitanate (tetraisopropoxytitanium), tetra n-butyl orthotitanate (tetra n- Other polytitanate esters, such as tetraalkyl orthotitanate (tetraalkoxytitanium) such as butoxytitanium), vanadyl triethylate, vanadyl triisopropylate, vanadyl tricholate such as vanadyl tri-n-butyrate, and the like can be used. This is the general formula RO
It can be represented by [Ti (OR) ₂ -O] mR, m is an integer of 2 or more, preferably 2 to 10, R is an alkyl group, an aryl group, or an aralkyl group, and all R are the same kind. It does not have to be a base and may be mixed. The carbon number of R is preferably 1-10, but is not particularly limited. Specifically, methyl polytitanate, ethyl polytitanate,
Polyisopropyl titanate, n-butyl polytitanate,
Examples include poly-n-hexyl titanate. In the above general formula, part of the alkoxy group may be a hydroxyl group.

A solid product, an electron-donating compound, which is a reaction product in the previous step,
The amount of the halogen-free transition metal compound used is 10 to 100,000 with respect to 100 g of the original solid product (I).
00 g, preferably 10 to 1,000 g, the halogen-free transition metal compound is 10 to 5,000 g, preferably 15 to 1,000 g,
Further, the amount of the halogen-free transition metal compound is 10 to 1,000 g, preferably 20 to 500 g, relative to 100 g of the electron donating compound.

The reaction conditions are 40 ° C to 300 ° C with stirring, preferably 50
The reaction is carried out at ℃ to 200 ℃ for 10 minutes to 20 hours, preferably 10 minutes to 10 hours.

It is not always necessary to use a solvent for the reaction, but it may be used for uniform reaction.

The amount of the solvent used is not more than about 10 times (weight) the solid product (I).

As the solvent to be used, the same solvent as that usable in the above (Step A) is used, but it is not necessary to be the same as the solvent used in the (Step A).

After the above reaction, separation is carried out according to a conventional method, using a solvent such as an aliphatic hydrocarbon or an aromatic hydrocarbon, at room temperature, preferably at 50 ° C. or higher, unreacted transition metal compound and electron donating compound The washing is repeated until no detection is performed, and the product is dried to obtain a solid product (II).

As for the reaction sequence of the above-mentioned halogen-containing or non-transition metal compound with respect to the solid product (I), either may be performed first. That is, as described above (step A), after (step B)
May be performed, or (A step) may be performed after (B step).

The catalyst of the production method according to the present invention is the solid product (II)
And an organoaluminum compound in combination. As the organic aluminum compound, triethylaluminum, triisobutylaluminum, trialkylaluminum such as trihexylaluminum, dialkylaluminum monohalide such as diethylaluminum monochloride, ethylaluminum sesquichloride, etc.,
In addition, there are alkoxyalkyl aluminums such as monoethoxy diethyl aluminum and diethoxy monoethyl aluminum.

The catalyst thus obtained is used for producing polyethylene. Examples of the α-olefin for copolymerization of ethylene include linear monoolefins such as propylene, butene-1, and hexene-1, branched monoolefins such as 4-methyl-pentene-1, and diolefins such as butadiene. To be

The polymerization reaction is usually carried out in a hydrocarbon solvent such as hexane, heptane, octane or decane. Polymerization temperature is 30 ℃
~ 150 ℃, preferably 50 ~ 120 ℃, polymerization pressure is normal pressure ~ 50kg
/ cm ² , preferably 3-40 kg / cm ² . During polymerization, an appropriate amount of hydrogen can be added to the polymerization system to control the molecular weight.

In the process of the present invention, a portion of the slurry in the polymerization system is continuously withdrawn in order to circulate the inert solvent and unreacted ethylene, hydrogen and the organoaluminum compound.
The taken-out slurry is separated into a gas portion, a solvent portion and a polyethylene portion, and the gas portion and the solvent portion are circulated to the polymerization system. On the other hand, the polyethylene part is dried in the drying step and then directly sent to the granulation step without a special catalyst deactivation treatment step to obtain polyethylene pellets.
Hereinafter, the manufacturing method of the present invention will be described with reference to the drawings.

FIG. 1 is a flowchart of a manufacturing apparatus according to a manufacturing method showing an embodiment of the present invention. First, the continuous suspension polymerization of ethylene in the presence of the inert solvent according to the present invention is carried out as follows. A solid product (II) diluted with a solvent, an organoaluminum compound diluted with a solvent, a replenishing solvent, hydrogen, ethylene from a pipe 1 to a polymerization vessel 7 having a stirrer and a jacket for removing heat of polymerization reaction. And a predetermined amount of α-olefin other than ethylene (in case of copolymerization). The temperature is maintained at the polymerization temperature,
By maintaining a given polymerization pressure and hydrogen partial pressure,
Concentration of slurry in container (polyethylene part / total slurry)
Gradually rises, but the slurry concentration in the container is reduced to 50% by the next slurry withdrawal and new supply of solvent and ethylene.
It is maintained at not more than 5% by weight, preferably 5 to 50% by weight. The most preferred concentration is 25-45% by weight. If it is less than 5% by weight, the production capacity is remarkably reduced, and if it exceeds 50% by weight, it is difficult to control the operation, and the quality tends to vary.

A part of the slurry containing polyethylene in the polymerization vessel 7 which has reached the predetermined slurry concentration is continuously taken out to the flash drum 9 by the control valve 8 installed in the extraction pipe. Gaseous portions, namely ethylene and hydrogen, are separated from the slurry depressurized in the drum, and these are returned to the polymerization vessel 7 by an ethylene and hydrogen circulation pipe 10 (the blower required for the pipe 10 is not shown). is there). The residence time and concentration of the slurry treated in the flash drum are not limited, but are usually 5 minutes to 1 hour and 20 ° C to 70 ° C.

The slurry separated from ethylene and hydrogen is pumped
It is sent to the next centrifuge 12 through an extraction pipe having 11, where the solvent portion and the polyethylene portion (wet cake) are continuously supplied.
Is separated into In addition to the solvent, the solvent portion contains most of the organoaluminum compound used for the polymerization and a small amount of a soluble low molecular weight polymer (note, so-called polyethylene wax). This portion is circulated to the polymerization vessel 7 by the pump 14 through the whole pipe 13, but a part or the whole thereof may be withdrawn from the pipe 15 depending on the operation need. The separated wet cake, on the other hand, consists mostly of polyethylene, with a small amount of solvent, respectively very small amounts of solid product (II), an organoaluminum compound and a soluble low molecular weight polymer. This part is dried by bringing the wet cake into contact with the heated nitrogen gas in the airflow drying pipe 17 by an airflow drying device consisting of an inert gas heater 23 directly connected to the centrifuge 12 and pipes 24, 17 and 19. , A cyclone 18 directly connected to the device separates dry polyethylene powder (Note, dry powder) and solvent vapor (Note, diluted with nitrogen). The dry polyethylene powder (including the note, the solid product (II), the organoaluminum compound and the soluble molecular polymer) collected by the cyclone 18 is passed through the powder tank 25 and without any catalyst deactivation treatment step. Granulated by the granulator 28. Further, known additives can be added from the pipes 26 and 27, if necessary.
The obtained polyethylene pellets are sent to a pellet tank 29 and then sent to a packing process through a pipe 30.

On the other hand, the solvent vapor is countercurrently cooled through a pipe 19 with a solvent previously cooled by a scrubber 20 (Note, 21 is a solvent cooler) to condense and separate the solvent in the solvent vapor, and the separated nitrogen gas is not removed again. It is sent to the active gas heater 23.

The solvent and the organoaluminum compound in the solvent separated and collected by the centrifugal separator 12 in the above method are 60 to 90% by weight of the portion contained in the slurry extracted through the valve 8 described above, respectively. The solvent collected at 20 is likewise 30 to 5% by weight. Therefore, the solvent and the organoaluminum compound, which are insufficient in the polymerization system only by circulation, are continuously supplied to the polymerization vessel 7 from the pipes 3 and 2. On the other hand, the solid product (II), which is the main catalyst component, is entirely carried away to the polyethylene product by one-time use, so that the required total amount must be constantly supplied from the pipe 1 described above.

The main effect of the present invention is to obtain a polyethylene having extremely high stability that does not require a catalyst deactivation treatment step as compared with the prior art.

The stability is shown by the tensile strength and elongation (according to JIS K6760-1977) after being left for 14 days in an oven at 110 ° C. in an air atmosphere, but the polyethylene by the method of the present invention has no tensile strength at all. It has not dropped. Also, the growth
It retains 150% or more, and can withstand a use environment sufficiently (Examples 1 to 5).

In comparison, a method using a final solid product (Comparative Example 1) according to the method of the previous invention or a final solid product lacking the necessary components used in the solid product (II) of the present invention as a catalyst (comparative) The polyethylenes according to Examples 2-9) have markedly reduced tensile strength and elongation.

Another effect of the present invention is that, firstly, the polymerization activity is extremely high,
The extremely high polymer yield makes the catalyst removal step unnecessary.

Secondly, the solvent recovery cost can be greatly reduced.

Since the recovery solvent according to the present invention does not contain any harmful substance that lowers the polymerization activity of the catalyst or hinders the polymerization of ethylene in the polymerization vessel, there is no limitation on the circulation ratio of the recovery solvent. Therefore, the amount of used solvent to be purified and recovered is extremely small, and the solvent recovery cost can be greatly reduced.

Thirdly, the high bulk specific gravity of polyethylene powder, which is an effect peculiar to the catalyst used in the present invention, can be maintained.
The third effect is a very important effect because it enables a long-term and stable continuous operation due to a high slurry concentration in the polymerization vessel.

Hereinafter, the present invention will be described with reference to examples. The meanings of the terms used in Examples and Comparative Examples are as follows.

BD: Bulk specific gravity (Unit: g / ml) MI: Melt index According to ASTM D-1238 (Unit:
g / 10 minutes) Tensile strength: According to JIS K6760-1977 (unit: kgf / cm ² ) Elongation: According to JIS K6760-1977 (unit:%) Example 1 (1) Production of solid product (I) Magnesium hydroxide 5.0 kg and 12 kg of aluminum trichloride (anhydrous) were mixed and pulverized in advance in a vibration mill having a capacity of 60 for 2 hours at room temperature, and then the content was transferred to a calcining reactor having a capacity of 30 and reacted at 150 ° C. for 5 hours. Then, the cooled reaction product was transferred to a vibration mill again and finely pulverized to obtain a solid product (I) 15
I got kg.

(2) Production of solid product (II) In a reactor equipped with a stirrer having a capacity of 100, toluene 20 was added under stirring.
, Chain dimethylpolysiloxane (viscosity 100 centistokes) 10 kg, and titanium tetrachloride 9.0 kg were added and mixed at room temperature, and then solid product (I) 10 kg was added, followed by heating to 80 ° C. and reacting for 3 hours. . Then the supernatant was removed. Toluene 20 in the remaining solid product, chain dimethylpolysiloxane 3k
After adding g (viscosity 100 centistokes) and 3 kg of tetra-n-butyl orthotitanate, reaction was carried out at 80 ° C. for 2 hours. After the reaction was completed, the reaction mixture was filtered with a filter device,
The solid product remaining after filtration was washed and filtered repeatedly with hexane 80 until no unreacted titanium compound and unreacted polysiloxane were detected in the washing solution.

The solid product after washing was then dried under reduced pressure to obtain a solid product (II). The content of titanium atoms in 1 g of the solid product (II) was 63 mg.

The above operations (1) and (2) were all performed in a nitrogen gas atmosphere containing no water. The same applies to the following examples and comparative examples.

(3) Production of polyethylene Homopolymerization of ethylene was performed using the continuous polymerization apparatus shown in FIG.

Solid product (II) from the pipe 1 to the polymerization vessel 7 with an internal volume of 100
N-hexane slurry containing 0.06 g / hr, n-hexane solvent containing 0.20 g / hr of triethylaluminum from the pipe 2, and n-hexane and scrubber 20 separated by a centrifuge 12 as a circulating solvent. The n-hexane condensed and recovered in (15.0 kg / hr in total, via pump 14 and pipe 16 together with pipes 13 and 22, respectively) is circulated to the polymerization vessel 7,
Purified n-hexane 3 kg / hr was similarly supplied from the pipes 1, 2 and 3 so that the supply amount of n-hexane was 18 kg / hr. Also, adjust the amount of hydrogen supplied so that the melt index of the polyethylene powder finally obtained by supplying 10 kg / hr of ethylene from the pipe 5 and hydrogen from the pipe 4 (Note, hydrogen and ethylene pipe 10 Circulation)
While conducting the polymerization, the polymerization temperature was 85 ° C. and the total pressure was 15 kg / cm ² for 72 hours.

The polymerized slurry that reached a certain concentration in the polymerizer 7 was continuously withdrawn to the flash drum 9 by the control valve 8. The unreacted ethylene and hydrogen separated in the flash drum 9 were circulated to the polymerization vessel 7 as described above. The polyethylene slurry from the flash drum 9 was introduced into the centrifuge 12 by the pump 11 and separated into the wet cake portion and the n-hexane portion. The wet cake was brought into contact with heated nitrogen gas at about 100 ° C., air-dried in a pipe 17, and dried polyethylene powder was obtained by a cyclone 18 at 9.9 kg / hr and sent to a powder tank 25. Ep is 8250, BD is
It was 0.47. On the other hand, the n-hexane portion separated by the centrifuge 12 and the n-hexane recovered by the scrubber 20.
As described above, 15 kg / hr of hexane is circulated to the polymerization vessel 7,
The rest was sent to the solvent recovery and refining process through pipe 15.

For the powder discharged from the powder tank 25, from the pipes 26 and 27, 2,6-di-tertiary-butyl-para-cresol 5 g / h
r and calcium stearate (10 g / hr) were mixed, respectively, and then sent to a granulator 28 having an inner diameter of 65 mm for granulation.

The pellet tank 29 contains 9.9k of granulated polyethylene.
Obtained at g / hr. The resulting polyethylene pellets have MI
It was 5.0. Further, the pellets were sent from the pipe 30 to the packing process to obtain the final product.

(4) Stability confirmation test From the polyethylene pellets obtained in (3) to JIS K6760
Test pieces were prepared according to -1977. The tensile strength and elongation of the prepared test piece were measured and found to be 320k each.
The value was gf / cm ² , 360%. Next, a test piece prepared in the same manner was left for 14 days in an open atmosphere under an air atmosphere kept at 110 ° C. When the tensile strength and the elongation of the test piece left to stand were measured, they were 331 kgf / cm ² and 210%, respectively.
The results are shown in the table.

Comparative Example 1 (1) Production of Solid Product (I) A solid product (I) was obtained in the same manner as in (1) of Example 1.

(2) Manufacture of final solid product A solid product (II) was manufactured according to the method of the previous invention (JP-A-57-42705).

That is, to a reactor with a stirrer having a capacity of 100, toluene 20, chain dimethylpolysiloxane (viscosity 100 centistokes) 10 kg, titanium tetrachloride 10 kg and tetra-n-butyl orthotitanate 3 kg are added with stirring at room temperature. Then, after adding 10 kg of the solid product (I) obtained in (1), 80 ° C
The temperature was raised to 3, and the reaction was performed for 3 hours. The reaction mixture was filtered with a filter, and the solid product remaining in the filter was washed with hexane 80 and washed and filtered repeatedly. The solid product after washing was then dried under reduced pressure to obtain a final solid product. The content of titanium atoms in 1 g of the final solid product was 55 mg.

(3) Production of polyethylene Polyethylene was produced in the same manner as in (3) of Example 1 except that the final solid product obtained in (2) was used instead of the solid product (II).

(4) Stability confirmation test The polyethylene pellets obtained in (3) were tested in the same manner as in Example 1- (4). The results are shown in the table together with the polymerization results.

Comparative Example 2 In (2) of Example 1, after the reaction with the solid product (I), the chain dimethylpolysiloxane, and the halogen-containing transition metal compound, when further reacting with the halogen-free transition metal compound, A final solid product was obtained in the same manner as in (2) of Example 1 except that the chain dimethyl polysiloxane was not used. Using this final solid product, the following is Comparative Example 1
It carried out similarly to. The results are shown in the table.

Comparative Example 3 (2) of Example 1 except that chain dimethyl polysiloxane was not used in the reaction of the solid product (I) with the halogen-containing transition metal compound in (2) of Example 1. The final solid product was obtained in the same manner as. Using this final solid product, the same procedure as in Comparative Example 1 was repeated. The results are shown in the table.

Comparative Example 4 A final solid product was prepared in the same manner as in Example 1 (2) except that tetra-n-butyl orthotitanate was not used.

Using this final solid product, the same procedure as in Comparative Example 1 was performed.

Comparative Example 5 A final solid product was prepared in the same manner as in Example 1 (2) except that titanium tetrachloride was not used.

Using this final solid product, the same procedure as in Comparative Example 1 was performed.

Comparative Example 6 A final solid product was prepared in the same manner except that 9 kg of ethyl polytitanate was used instead of titanium tetrachloride in (2) of Example 1.

Using this final solid product, the same procedure as in Comparative Example 1 was performed.

Comparative Example 7 A final solid product was prepared in the same manner as in Example 1 (2) except that 9 kg of silicon tetrachloride was used instead of titanium tetrachloride.

Using this final solid product, the same procedure as in Comparative Example 1 was performed.

Comparative Example 8 A final solid product was prepared in the same manner as in Example 1 (2) except that 3 kg of titanium tetrachloride was used instead of tetra-n-butyl orthotitanate.

Using this final solid product, the same procedure as in Comparative Example 1 was performed.

Comparative Example 9 3 kg of aluminum tri-n-butoxide was used instead of tetra-n-butyl orthotitanate in (2) of Example 1.
The final solid product was prepared in a similar manner except using

Using this final solid product, the same procedure as in Comparative Example 1 was performed.

Example 2 (1) Production of solid product (I) 5.0 kg of magnesium oxide and aluminum trichloride (anhydrous) 1
After 1 kg was mixed and pulverized in a vibrating mill having a capacity of 60 at room temperature for 3 hours in advance, the contents were transferred to a calcining reactor having a capacity of 60 and reacted at 200 ° C. for 2 hours. Then, the cooled reaction product was transferred to a vibration mill again and finely pulverized to obtain a solid product (I) 14
I got kg.

(2) Production of solid product (II) In a reactor equipped with a stirrer having a capacity of 100, toluene 20 was added under stirring.
, Tetraethoxysilane 7kg and titanium tetrachloride 13.0k
g and mixed at room temperature, followed by solid product (I) 1
After adding 0 kg, the temperature was raised to 90 ° C. and the reaction was carried out for 3 hours. Next, without removing the supernatant, 2 kg of tetraethoxysilane and 4 kg of tetra-n-butyl orthotitanate were added, and the mixture was reacted at 90 ° C. for 2 hours. After the reaction was completed, the reaction mixture was filtered with a filtration device, and the solid product remaining after filtration was washed and filtered repeatedly with hexane 80 until no unreacted titanium compound was detected in the washing liquid. The solid product after washing was then dried under reduced pressure to obtain a solid product (II). The content of titanium atoms in 1 g of the solid product (II) was 55 mg.

(3) Polyethylene was produced in the same manner as in Example 1 except that the solid product (II) obtained in (2) above was used.

(4) Using the polyethylene pellets obtained in (3) above, a stability confirmation test was performed in the same manner as in Example 1 below. The results are shown in the table.

Example 3 (1) Production of solid product (I) Hydromagnesite (3MgCO ₃ .Mg (OH) ₂ .3H ₂ O) 6.0k
g and ferric trichloride (anhydrous) 9.0 kg in advance in a vibration mill with a capacity of 60 for 2 hours at room temperature, and then crush the contents.
The mixture was transferred to a baking reactor of 60 and reacted at 300 ° C. for 1 hour.

Then, the cooled reaction product was transferred again to the vibration mill and finely pulverized to obtain 13 kg of a solid product (I).

(2) Production of solid product (II) In a reactor equipped with a stirrer and having a capacity of 200, toluene 20 was added under stirring.
, 7 kg of anisole and n-butyl polytitanate (3
4 kg of the monomer) was added and mixed at room temperature, and subsequently 10 kg of the above solid product (I) was added, then the temperature was raised to 80 ° C. and the reaction was carried out for 3 hours.

Next, 10 kg of titanium tetrachloride was added without removing the supernatant (that is, in the state where unreacted anisole was present), and the reaction was carried out at 80 ° C. for 1 hour.

After the reaction was completed, the reaction mixture was filtered with a filtration device, and the solid product remaining after filtration was washed and filtered repeatedly with hexane 80 until no unreacted titanium compound was detected in the washing liquid. The solid product after washing was then dried under reduced pressure to obtain a solid product (II). The content of titanium atoms in 1 g of the solid product (II) was 32 mg.

(3) Polyethylene was produced in the same manner as in Example 1 except that the solid product (II) obtained in (2) above was used.

(4) Using the polyethylene pellets obtained in (3) above, a stability confirmation test was performed in the same manner as in Example 1 below. The results are shown in the table.

Example 4 (1) Production of solid product (I) Hydrotalcite (Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O) 6 kg and aluminum trichloride (anhydrous) 9 kg in a vibration mill having a capacity of 60 After mixing and pulverizing for 2 hours, the contents were transferred to a calcination reactor having a capacity of 60 and reacted at 120 ° C. for 4 hours. After cooling, the cooled reaction product was transferred again to the vibration mill and finely ground to obtain 14 kg of a solid product (I).

(2) In (2) of Example 1, using the above solid product (I), 10 kg of octaethylcyclotetrasiloxane (viscosity 10 centistokes) was used twice instead of dimethylpolysiloxane, a total of 20 kg, and ortho A solid product (II) was prepared in the same manner except that 3 kg of vanadyl tributyrate was used instead of tetra-n-butyl titanate.

(3) Polyethylene was produced in the same manner as in (3) of Example 1 except that this solid product (II) was used.

(4) Using the polyethylene pellets obtained in (3) above, a stability confirmation test was performed in the same manner as in Example 1 below. The results are shown in the table.

Example 5 The solid product (II) obtained in Example 1 was used to polymerize ethylene-propylene.

In (3) of Example 1, propylene 3% (volume%)
An ethylene-propylene copolymer was produced in the same manner as in Example 1 except that the contained ethylene was introduced, and the obtained pellets were subjected to a stability confirmation test. The results are shown in the table.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram of a continuous polyethylene production apparatus used in the present invention. In the figure, 1 to 6 are supply pipes for various reaction materials, 7 is a polymerizer, 9 is a flash drum, 10 is an ethylene and hydrogen circulation pipe, 12 is a centrifugal separator, 16 is a solvent circulation pipe, and 17 is wet cake airflow drying. A pipe, 18 is a cyclone, 19 is a solvent recovery pipe, 20 is a scrubber, 25 is a powder tank, 26 and 27 are additive supply pipes, 28 is a granulator, 29 is a pellet tank, and 30 is a polyethylene pellet acquisition pipe. FIG. 2 is a flow chart for explaining the manufacturing process of the catalyst according to the present invention.

Claims (9)

[Claims] 1. A solid product (I) obtained by reacting a trivalent Al or Fe halide with Mg hydroxide, oxide, carbonate, or a double salt containing these, and an electron donating compound. Also, ethylene is polymerized to produce polyethylene by using a catalyst in which a transition metal compound-supported final solid product obtained by reacting a transition metal compound of group 4a or group 5a of the periodic table is combined with an organoaluminum compound. In the process, the solid product (I) is (step A) polysiloxane, represented by the general formula ▲ R ¹ _m ▼ Si (OR ² ).
A step of reacting a compound represented by the general formula TiX ₄ (X is a halogen) (hereinafter referred to as a halogen-containing Ti compound) in the presence of one or more electron-donating compounds selected from _4- m or ether (hereinafter referred to as Step A) And (Step B) polysiloxane, general formula ▲ R ¹ _m ▼ Si (OR ² ).
_{In the} presence of one or more electron-donating compounds selected from _4- m or ether, the general formula Ti (OR) ₄ , RO [Ti (OR)
₂ O] mR or VO (OR) ₃ (in the above, R is alkyl), a step of reacting one or more compounds (hereinafter referred to as halogen-free transition metal compound) (hereinafter referred to as Step B) Using the obtained solid product (II) as the final solid product bearing a transition metal compound, continuous suspension polymerization is carried out in the presence of an inert solvent, and a part of the obtained slurry containing polyethylene is continuously taken. Separated into a gaseous part, a solvent part and polyethylene outside the polymerization system, and circulating the gaseous part and a solvent part in the polymerization system, the polyethylene part is directly subjected to a drying step without undergoing a catalyst deactivation treatment step. A method for producing polyethylene, characterized by being sent to a granulation step. 2. An electron donating compound represented by the general formula: (Wherein R ₁ or R ² is the same or different residue capable of bonding to silicon, and 3 ≦ n ≦ 10,000), and the polysiloxane represented by the formula (1) is used. The manufacturing method described. 3. A solid product obtained by subjecting a solid product (I) to a reaction of (step A) and then a reaction of (step B) as a final solid product carrying a transition metal compound. The manufacturing method according to claim (1), which uses (II). 4. A solid product obtained by subjecting a solid product (I) to a reaction of (step B) and then a reaction of (step A) as a final solid product carrying a transition metal compound. The manufacturing method according to claim (1), which uses (II). 5. The polyethylene concentration in the slurry is 50% by weight.
The manufacturing method according to claim (1), characterized in that the content is maintained at 5% by weight or more. 6. The production method according to claim 1, wherein a slurry containing polyethylene is separated into a solvent portion and a wet cake by a centrifugal separation method, and the separated solvent portion is circulated in a polymerization system. 7. The method according to claim 1, wherein the wet cake is air-flow dried to separate into solvent vapor and dry powder, and the solvent in the separated solvent vapor is condensed and liquefied and circulated in the polymerization system. The manufacturing method described. 8. The production method according to claim 1, wherein a portion of the organoaluminum compound that is insufficient in the solvent to be circulated is newly supplied into the polymerization system. 9. The production method according to claim 1, wherein a hydrogen gas, which is insufficient for the hydrogen gas in the gas portion to be circulated, is newly supplied into the polymerization system.