JPS6360766B2 - - Google Patents

Description

[Detailed description of the invention]

[] BACKGROUND OF THE INVENTION The present invention relates to a method for homopolymerizing and copolymerizing ethylene at a high temperature of 125°C or higher and under a high pressure of over 200 kg/cm ² using an extremely highly active Ziegler type catalyst. There are two methods for polymerizing ethylene that are used on a large scale industrially. The first method is to process ethylene at high temperature and pressure.
For example, polymerization is carried out at a temperature of 125° C. or higher and 500 kg/cm ² or higher, typically 140-300° C. and 1000-3000 kg/cm ² or higher. Polymerization is carried out in the presence of a polymerization initiator consisting of a compound capable of generating free radicals, typically peroxide or oxygen or a combination thereof. This method is generally referred to as the "high pressure method" and is characterized by the production of branched polyethylene. The second method involves producing ethylene at relatively low temperatures and pressures, such as below 250°C and below 200 kg/ ^cm2 .
Usually, polymerization is carried out under conditions of 50 to 90°C and 30 kg/cm ² or less. A typical catalyst used in this method is an organometallic complex compound also called a "Ziegler type catalyst." The term "Ziegler-type catalyst" is used for a catalyst consisting of a combination of a compound of a transition metal of groups a to a of the periodic table and an organometallic compound of a metal of group - of the periodic table. The widely used Ziegler-type catalysts are based on a combination of a titanium compound, such as titanium tetrachloride or titanium trichloride, and an aluminum compound, such as triethylaluminum or diethylaluminum chloride. Products made using the Ziegler process, or low pressure process, are linear polyethylene with virtually no branching, and have a melting point of over 130℃, compared to the typical high pressure process polyethylene, which has a melting point in the range of 105 to 120℃. have. Furthermore, the specific gravity of low-pressure polyethylene is generally higher than that of high-pressure polyethylene, typically less than 0.935 for high-pressure polyethylene, whereas the specific gravity of low-pressure polyethylene is typically greater than 0.95, usually about 0.96. . By the way, a third method has been proposed, although it has not been generalized as a large-scale industrial manufacturing method for polyethylene. For example, British Patent No. 828828 discloses that olefins, ^particularly ethylene, are reacted with Ziegler-type catalysts (i.e. organometallic compounds a, a or A method has been proposed in which olefin is polymerized by adding 25 to 500 ppm by weight of a chain compound catalyst with a compound other than the oxide of a group metal. Since then, many improved techniques have been proposed for this method of polymerizing ethylene using ionic polymerization catalysts such as Ziegler catalysts under high temperature and high pressure, but all of them are fully satisfactory in the following two points. It was difficult to say the least. The first point is that the catalyst activity is not high enough.
For this reason, the amount of catalyst residue in the produced olefin polymer is large, and therefore, if the catalyst decomposition and purification steps are omitted, the product polymer will be a colored product with a strong odor that is susceptible to thermal and oxidative deterioration. In particular, the ionic polymerization method under high pressure and high temperature often uses polyethylene production equipment using high-pressure radical polymerization, but if catalytic decomposition and purification steps are required, large-scale equipment modifications are required. Improving catalyst activity is an important point in commercializing this technology from the viewpoint of a significant increase in polymer production costs. Furthermore, in the ionic polymerization method under high pressure and high temperature, it is necessary to supply the catalyst to the reactor using a high-pressure pump. In addition, the solid catalyst concentration in the catalyst dispersion is also limited. Therefore, from the viewpoint of reducing the amount of solvent used and downsizing the high-pressure pump, it is preferable that the catalyst activity is sufficiently high. Furthermore, since catalytic activity generally decreases when ethylene and α-olefin are copolymerized, an even more highly active catalyst is required for copolymerization. A second problem is that the melt flow index (abbreviated as MFR) of polymers produced by ionic polymerization at high temperatures cannot be reduced to a sufficiently low region. This places an upper limit on the polymerization reaction temperature in relation to the targeted MFR of the polymer, which in turn limits the polymer yield. Polymerization is usually carried out in the presence of one or more chain transfer agents (e.g. hydrogen), but at high temperatures the chain transfer reaction increases due to factors other than the action of the chain transfer agent, and the supply of chain transfer agents can be stopped. However, the MFR of the polymer does not decrease sufficiently. Therefore, in industrializing this technology, the development of a catalyst with good controllability of MFR in a sufficiently high temperature range has been an extremely important issue. [] Summary of the Invention The present invention aims to provide a solution to the above two points, and attempts to achieve this aim by using a transition metal catalyst produced in a specific manner. Therefore, the method of polymerizing ethylene according to the invention requires pressures exceeding 200 Kg/cm ² and at least 125 kg/cm 2 .
It is characterized in that ethylene or ethylene and at least one other α-olefin are brought into contact with a catalyst consisting of a combination of components A and B as described below at a temperature of °C. Component A (1) General formula R ¹ _3-n AlX ¹ _n (where R ¹ is a carbon number of 1 to 10
hydrocarbon residue, X ¹ is halogen or hydrogen,
m is a number of 0≦m≦2) and the compound represented by the formula R ² _3-o Al(OR ³ ) _o (where R ²
and R ³ is a hydrocarbon residue having 1 to 10 carbon atoms, n
is a number of 1≦n≦2)
a mixture of organoaluminum compounds consisting of 75 to 1 mol %, or (2) general formula R ¹ _3-n AlX ¹ _n (where R ¹ is a carbon number of 1 to 10
hydrocarbon residue, X ¹ is halogen or hydrogen,
m is a number of 0≦m≦2) and 10 to 90 mol% of the compound represented by the formula (Here, R ⁴ to ^{R 8} are each a saturated hydrocarbon group having 1 to 10 carbon atoms, but R ⁸ is a halogen atom or It can also be a group represented by R ⁹ to ^{R 11} are each a saturated hydrocarbon group having 1 to 10 carbon atoms. ) A mixture of an organoaluminum compound and an alkylsiloxalane derivative, consisting of 90 to 10 mol% of the compound represented by: Component B: A solid product obtained by contacting a titanium compound with a trivalent or tetravalent titanium valence and magnesium dihalide (however, the magnesium dihalide has a surface area that decreases before or after contact with the titanium compound). at least 5 m ² /g). EFFECTS According to the present invention, the homopolymerization of ethylene and the copolymerization of ethylene with at least one other α-olefin can be carried out using this particular Ziegler type catalyst at pressures exceeding 200 Kg/cm ² and temperatures of at least 125°C. If you do this, you will get significant results in the following two ways. The first point is that both the amount of polymer produced per transition metal and the amount of polymer produced per carrier are high, so the resulting polymer is less susceptible to thermal and oxygen degradation and is less susceptible to color and odor. It will be very good. The second point is that a polymer with a sufficiently low MFR can be obtained under polymerization temperature conditions that provide an industrially high polymer yield. The reason for this is not necessarily clear, but as component A, a mixture of two specific organoaluminum compounds at a specific ratio,
Alternatively, it can be obtained by using a mixture of a specific organoaluminum compound and an alkylsiloxalane derivative in a specific ratio. Even if the above mixture is used in a region that does not meet the specific mixing ratio of the present invention, it will not affect the catalyst activity or polymer MFR control.
In either case, a fully satisfactory result cannot be obtained. [] Detailed description of the invention 1 Catalyst used The catalyst used in the present invention consists of a combination of component A and component B below. This catalyst belongs to the category of "Ziegler type catalyst" and has component A
can also be considered as a cocatalyst for component B, which is a transition metal component. 1 Component A Cocatalyst component A used in the present invention
is a mixture of organoaluminum compounds defined in (1) or (2) below. (1) General formula R ¹ _3-n AlX ¹ _n (where R ¹ is carbon number 1~
10, preferably 1 to 6, hydrocarbon residues, X ¹
is hydrogen or halogen, preferably chlorine, and m is a number of 0≦m≦2) 25 to 99 mol%, preferably 30 to 95 mol%
and the formula R ² _3-o Al(OR ³ ) _o (where R ² and R ³ and a hydrocarbon residue having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and n is a number of 1≦n≦2) A mixture of organoaluminum compounds comprising 75 to 1 mol%, preferably 70 to 5 mol% of a compound represented by (2) General formula R ¹ _3-n AlX ¹ _n (where R ¹ is carbon number 1~
10, preferably 1 to 6, hydrocarbon residues, X ¹
is hydrogen or halogen, preferably chlorine, and m is a number of 0≦m≦2) 10 to 90 mol%, preferably 15 to 80 mol%
and expression (Here, R ⁴ to R ⁸ each have 1 to 10 carbon atoms,
Preferably 1 to 6 saturated hydrocarbon groups or hydrogen, but R ⁸ is a halogen atom or It can also be a group represented by R ⁹ to ^{R 11} are each a saturated hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, or hydrogen. ) A mixture of an organoaluminum compound and an alkylsiloxalane derivative, comprising 90 to 10 mol%, preferably 85 to 15 mol%, of a compound represented by: Specific examples of the organoaluminum compound represented by the above general formula R ¹ _3-n AlX ¹ _n include (a) trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum; Trialkylaluminum such as aluminum, (b) Alkylaluminum halides such as diethylaluminum monochloride, diisopropylaluminum monochloride, diisobutylaluminum monochloride, ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum monobromide, diisopropylaluminum monobromide, ( c) Dialkyl aluminum hydrides such as diethyl aluminum hydride and diisobutyl aluminum hydride. Among these organoaluminum compounds, dialkylaluminum monochloride, particularly diethylaluminium monochloride, is most suitable. Specific examples of organoaluminum compounds represented by the general formula R ² _3-o Al(OR ³ ) _o include dimethylaluminum ethoxide, diethylaluminum ethoxide, diethylaluminium propoxide, diethylaluminum butoxide, diethylaluminum phenoxide, Examples include ethylaluminum diethoxide. Among these, dialkylaluminum alkoxides, particularly diethylaluminum ethoxide, diethylaluminium propoxide, and the like are preferred. Also general formula (Here, R ⁴ to ^{R 8} each have 1 to 10 carbon atoms,
Preferably 1 to 6 saturated hydrocarbon groups or hydrogen, R ⁸ is a halogen atom or It can also be a group represented by R ⁹ to ^{R 11} are each a saturated hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, or hydrogen. ) The main manufacturing methods and specific examples of the compound represented by are as follows. (b) Reaction between trialkylsilanol and trialkylaluminium, e.g. Specific examples of siloxalane obtained by this production method are as follows.

[Table] (b) Reaction between cyclic siloxane and trialkylaluminum, e.g. Specific examples of siloxalane obtained by this production method are as follows. Octamethylcyclotetrasiloxane 1 mole +
4 moles of triethylaluminum → dimethylethyldiethylsiloxalane In the above reaction, if 2 moles of triethylaluminum is used for 1 mole of octamethylcyclotetrasiloxane, the Si/Al ratio is approximately equal to 2, and the siloxalane as shown in the following formula is obtained. is obtained. Si/Al of such alkylsiloxalane
The atomic ratio of is preferably 1 to 3. (c) Reaction between polysiloxane (silicon oil type) and trialkylaluminum, e.g. Specific examples of siloxalane obtained by this production method are as follows. When a polysiloxane is used as a starting material for synthesizing an alkylsiloxalane in this way, the alkylsiloxalane can take the form of a polymer. In this case as well, the atomic ratio of Si/Al is 1
~3 is preferred. Particularly preferred compounds among these alkylsiloxalane include methylethylhydrodiethylsiloxalane, dimethylethyldiethylsiloxalane, trimethyldimethylsiloxalane, trimethyldiethylsiloxalane, trimethyldipropylsiloxalane, triethyldimethylsiloxalane, and triethyldiethylsiloxalane. Examples include saran and triethyldipropylsiloxalane. 2 Component B Component B is a solid product obtained by contacting a titanium compound whose titanium valence is trivalent or tetravalent with magnesium dihalide. However, the dihalogenated magnesium compound has a surface area of at least 5 m ² /g before or after contact with the titanium compound. (1) Titanium compounds whose titanium has a trivalent valence Specific examples of titanium compounds whose titanium has a trivalent valence are titanium trihalides, preferably TiCl ₃ ,
It can also be a product obtained by reacting TiCl ₃ with an alcohol or other compound. TiCl ₃ can be produced by various methods, and one example is as follows. (a) TiCl ₄ is reduced with hydrogen at a temperature of 600℃ or higher. (b) Reducing TiCl ₄ with aluminum. (c) Reducing TiCl ₄ with an organoaluminium compound. (2) Titanium compounds in which titanium has a tetravalent valence Examples of titanium compounds in which titanium has a tetravalent valence include the following compounds. ( ^a ) General formula Ti(OR ¹² ₎ ^{4 -} _p
Preferably represents chlorine or bromine, p is 0≦
(indicating a number of p≦4). Specific examples include TiCl ₄ , TiBr ₄ , Ti
(OC ₂ H ₅ ) ₄ , Ti(O-iC ₃ H ₇ ) ₄ , Ti(O-
nC ₄ H ₉ ) ₄ , Ti(OC ₆ H ₅ ) ₄ , Ti(O-nC ₄ H ₉ )Cl ₃ , Ti(O
-nC ₄ H ₉ ) ₂ Cl ₂ , Ti(O-nC ₄ H ₉ ) ₃ Cl, Ti(O-
iC ₃ H ₇ ) ₃ Cl, Ti(O-iC ₃ H ₇ ) ₂ Cl ₂ , Ti(O-iC ₃ H ₇ )Cl ₃ , Ti(OC ₆ H ₅ )Cl ₃ , Ti(OC ₆ H ₅ ) ₂ Cl ₂ etc. (b) General formula (Here, R ¹³ to R ¹⁶ each have a carbon number of 1 to
10, preferably 1 to 6, representing a saturated hydrocarbon group, where q is a number up to 20). (c) A titanium halogen compound represented by the formula Ti( ^{OR 17} ₎ ⁴ _- ^r Halogens are preferred, especially chlorine and bromine;
(r represents a number of 2≦r<4, preferably 2≦r≦3) and an alcohol compound. The number of moles of the alcohol compound added is about 1×10 ^-3 to 6, preferably about 0.5 to 2 moles, per mole of the titanium halogen compound. Here, the term "alcohol compound" includes monohydric to tetrahydric alcohols having about 1 to 20 carbon atoms, phenols, and silanol compounds. This complex is composed of a titanium halogen compound represented by the above formula and an alcohol compound, and is not necessarily limited to a complex obtained by the reaction of both compounds. Therefore, for example, it can also be produced by reacting titanium tetraalkoxide with a halogenated hydrocarbon or a halogen compound. For example, Ti(O—nC ₄ H ₉ ) ₂ Cl ₂ ·nC ₄ H ₉ OH can be synthesized using the following formula. Ti(O-nC ₄ H ₉ ) ₄ +2HCl→Ti(O-nC ₄ H ₉ ) ₂ Cl ₂・
nC ₄ H ₉ OH + nC ₄ H ₉ OH A specific example of this complex is Ti(OC ₂ H ₅ ) ₂ Cl・
C ₂ H ₅ OH, Ti(OC ₂ H ₅ ) ₂ Cl ₂・3C ₂ H ₅ OH, Ti(OC ₂ H ₅ ) ₂ Cl ₂・C ₄ H ₉ OH, Ti(OC ₂ H ₅ ) ₃ Cl・
C ₂ H ₅ OH, Ti (OC ₂ H ₅ ) ₃ Cl・CH ₃ OH, Ti (O—iC ₃ H ₇ ) ₂ Cl ₂・iC ₃ H ₇ OH, Ti (O—
nC ₄ H ₉ ) Cl ₂・C ₂ H ₅ OH, Ti(O-nC ₄ H ₉ ) ₂ Cl ₂・
nC ₄ H ₉ OH, Ti(O- nC ₄ H ₉ ) ₃ Cl・2nC ₄ H ₉ OH, Ti(O-
nC ₄ H ₉ ) ₂ Cl ₂・4C ₄ H ₉ OH, Ti (O―nC ₆ H ₁₃ ) ₂ Cl ₂・
C ₈ H ₅ OH, Ti(OC ₂ H ₅ ) ₂ Cl ₂・C ₆ H ₅ OH, Ti(OC ₂ H ₅ ) ₃ Cl・
Examples include C ₆ H ₁₃ OH, Ti(OC ₂ H ₅ ) ₂ Br ₂・C ₂ H ₅ OH, Ti(OC ₂ H ₅ ) ₂ Cl ₂・(CH ₃ ) ₃ SiOH, and the like. Preferred specific examples of these include Ti(OC ₂ H ₅ ) ₂ Cl ₂・C ₂ H ₅ OH, Ti(O-
nC ₄ H ₉ ) ₂ Cl ₂・C ₂ H ₅ OH, Ti (O-nC ₄ H ₉ ) ₂ Cl ₂・
Examples include C ₄ H ₉ OH. (3) Magnesium dihalide The magnesium dihalide to be brought into contact with the above titanium compound to form component B is as follows:
Examples include MgF ₂ , MgCl ₂ , MgBr ₂ and MgI ₂ . Among these, _MgCl2 is preferred. In the present invention, it is necessary that the dihalogenated magnesium be "activated". That is, the magnesium dihalide must have a surface area of 5 m ² /g or more, preferably 10 m ² /g or more, and more preferably 15 m ² /g or more before and/or after contact with the titanium compound. . A specific example of "activated" magnesium dihalide is one whose surface area is 5 m ² /g or more before contact with the titanium compound, for example, by pulverizing magnesium dihalide or dissolving it in an organic solvent such as alcohol or ether. It was obtained by evaporating the solvent from the solution and precipitating it. Another specific example of activated magnesium dihalide is one in which the magnesium dihalide is pulverized during or after contact with a titanium compound to have a surface area of 5 m ² /g or more (magnesium dihalide has a surface area of 5 m 2 /g or more). (The surface area may be 5 m ² /g or more before contact with the material). When the surface area of magnesium dihalide is pulverized after contact with a titanium compound, the surface area of magnesium dihalide can be measured on a product after the supported titanium compound has been sufficiently washed away. The surface area of B) can be used instead. The magnesium dihalide may be modified by contacting it with an electron donor, such as an alcohol, provided it meets the surface area requirements. (4) Contact method Catalyst component B of the present invention can be produced by the method shown below. One preferred method consists in mixing and grinding the aforementioned titanium compound and magnesium dihalide to a surface area of at least 5 m ² /g. Preferably, the surface area is greater than or equal to 10 m ² /g, most preferably greater than or equal to 15 m ² /g. In order to achieve such a state, the pulverization method, pulverization conditions, pulverization time, etc. may be appropriately selected and pulverized. As the crushing device, a ball mill, a vibration mill, a rod mill, an impact mill, and various other devices can be used. With these pulverizers, the pulverization time required to obtain the desired catalyst depends on a combination of various conditions such as ball filling rate, pulverized sample filling rate, ball diameter, rotation speed or vibration frequency, and pulverization temperature. They vary, but an example is: internal volume 0.46 liters, ball diameter 16 mm, ball volume/
When pulverizing is performed under the conditions of a bottle volume of 0.2 and a rotational speed of 90 rpm, more than 1 hour is required. If necessary, pulverization can be carried out either wet or dry. Another method for producing component B is to produce the magnesium dihalide itself under the above-mentioned grinding conditions to a surface area of at least 5 m ² /g, and then to contact it with the titanium compound by stirring in the presence of an inert diluent. be. After the contact, further wet or dry pulverization may be performed. The amount of the titanium compound used in the production of the supported catalyst may be arbitrary as long as the effects of the present invention are observed, but generally the weight percentage of titanium relative to the solid catalyst component B to be produced is
Amounts in the range 0.1-10, especially 0.5-10 are preferred. The temperature at which the titanium compound and the magnesium dihalide are brought into contact is preferably −20°C.
-200°C, more preferably 0-150°C. 3 Usage ratio of component A and component B There is no particular restriction on the usage ratio of component A and component B, but the Al/Ti atomic ratio is preferably in the range of 1 to 1000, more preferably 1 to 100. range. 4. Preparation of Catalyst Component A and B described above may be combined within or outside the polymerization zone. Since solid component A or component A and component B are injected into the high-pressure polymerization zone using a high-pressure pump, these must be in the form of liquid or fine particles or a slurry thereof, and therefore the particle size must be approximately 10 μm or less. , preferably about 1 to 5 μm. If desired, component B prepared as described above may be further treated with an electron donor, such as an alcohol compound (examples are as described above). 2 Polymerization of Ethylene 1 Polymerization Apparatus The polymerization method of the present invention can be carried out as a batch operation, but it is more preferable to carry out the polymerization in a continuous manner. As the polymerization apparatus, an apparatus commonly used in high-pressure radical polymerization of ethylene can be used. Specifically, there is a continuous stirring tank reactor or a continuous tubular reactor. The polymerization can be carried out as a single zone process using these single reactors, but it can also be carried out using many reactors in series, possibly in series with a condenser, or
Alternatively, a single reactor can be used, the interior of which is effectively divided into several zones for a multi-zone process. In a multi-zone process, monomers are added to each reactor or reaction zone in such a way that the reaction conditions in each zone are different to control the properties of the polymer obtained in each reactor or reaction zone. It is common to adjust the composition, catalyst concentration, and molecular weight modifier concentration. When multiple reactors are connected in series, in addition to the combination of two or more tank reactors or two or more tubular reactors, one or more tank reactors and one or more pipe reactors are used. Combinations with type reactors can also be used. The polymer produced in one or more reactors can be separated from unreacted monomers and treated as in conventional high-pressure processes without removing catalyst residues. can. Removal of catalyst residue is
In the conventional method using Ziegler catalysts at low pressure,
This is a very expensive and time consuming process. The unreacted monomer mixture is mixed with an additional amount of the same monomer, repressurized and recycled to the reactor. The additional amount of monomer added as described above is of a composition that returns the composition of the mixture to that of the original feed, and generally this additional amount of monomer is added to the polymer separated from the polymerization vessel. It has a composition roughly equivalent to that of the coalescence. The catalyst is, for example, injected as a finely divided dispersion in a suitable inert liquid directly into the reactor using a high-pressure pump. Suitable inert liquids include:
Examples include white spirits, hydrocarbon oils, pentane, hexane, cyclohexane, heptane, toluene, higher branched chain saturated aliphatic hydrocarbons, and mixtures of these liquids. The dispersion is preferably kept under a nitrogen blanket to avoid contact with water and air before introducing it into the reactor. Ethylene and other monomers must also be substantially free of water and oxygen. As mentioned above, the resulting polymer can be processed without removing the catalyst. This is because the catalyst used in the present invention has a very high activity, and therefore a high conversion rate of monomer to polymer can be achieved using an extremely small proportion of catalyst. 2. Monomers and comonomers and resulting polymers The polymerization carried out using the catalyst system of the present invention is homopolymerization of ethylene or ethylene and the general formula R
- copolymerization with at least one other α-olefin represented by CH=CH ₂ . In the case of homopolymerization of ethylene, the resulting polymer has a specific gravity of 0.95
High density polyethylene in the range of ~0.97 is typical. General formula R-CH=CH ₂ (where R has 1 to 12 carbon atoms
is a hydrocarbon residue. ) Specific examples of comonomers represented by are propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, 4-methylpentene-
1, decene-1, etc. These α-olefins can be copolymerized in the resulting copolymer in an amount of up to 30% by weight, preferably from 3 to 20% by weight.
Copolymerization of ethylene and these α-olefins yields polymers with a wide range of specific gravities.
The specific gravity of the resulting polymer is controlled by the type of comonomer, the feed composition of the comonomer, and the like. Specifically, a polymer having a desired density within the range of about 0.890 to 0.955, preferably about 0.89 to 0.94 can be obtained. The method of the present invention is particularly suitable for producing the above-mentioned copolymers, and can provide medium to low density ethylene copolymers in high yields. These copolymers not only have a density different from that of conventional low-pressure processed high-density polyethylene, but also have different properties from conventional high-pressure processed low-density polyethylene, namely, they have substantially no long chain branching and molecular weight. It has a narrow distribution (Q value) of 3 to 5, and is a polymer excellent in mechanical strength, especially tensile strength, and environmental destructive stress. 3 Polymerization conditions (1) Polymerization pressure The polymerization pressure employed in the present invention is 200
The pressure exceeds Kg/ ^cm2 , preferably 300~
4000Kg/cm ² , more preferably 500 to 3000Kg/cm ² ,
is within the range of (2) Polymerization temperature The polymerization temperature is at least 125°C, preferably in the range of 150 to 350°C, more preferably
It is within the range of 200-320°C. Although not essential, under the combination of polymerization pressure and temperature employed, the polymerization reaction mixture may form a single fluid phase or may separate into two phases. (3) Reactor feed gas composition The reactor feed gas composition employed in the present invention includes 5 to 100% by weight of ethylene, 0 to 95% by weight of at least one α-olefinic comonomer, and as a molecular weight regulator. Usually, the hydrogen content is in the range of 0 to 20 mol%. (4) Residence Time The average residence time in the reactor is related to the duration of activity of the catalyst under the reaction conditions employed. The half-life of the catalyst used is influenced by temperature among other reaction conditions, and as the lifetime of the catalyst increases, it is preferable to increase the residence time of the monomer in the reactor. The average residence time employed in the present invention is in the range of 2 to 600 seconds, preferably 10 to 150 seconds.
seconds, more preferably within the range of 10 seconds to 120 seconds. (5) Others From the viewpoint of polymerization temperature and pressure, the polymerization method according to the present invention belongs to the category of high-pressure polymerization of ethylene. Therefore, the polymerization method according to the present invention is carried out substantially without using a liquid dispersion medium, except for a small amount of liquid medium introduced as a dispersion medium for the catalyst or for other purposes. Therefore, in the method of the present invention, it is only necessary to separate unreacted monomers from the polymer after polymerization, and separation of the liquid medium from the polymer and purification of the liquid medium are not necessary. According to the method of the present invention, the amount of catalyst residue in the produced polymer is extremely small, so there is no need to decompose or purify the catalyst, and the produced polymer is separated from unreacted monomers in a separator. After that, it becomes a product. This product may be used as is, or may be subjected to various post-treatment steps such as those already used for products obtained by high-pressure radical polymerization. 3 Experimental Examples 1 Production of catalyst components A stainless steel pot with an internal volume of 460 ml and an inner diameter of 95 mmφ was filled with 43 stainless steel balls of 16 mmφ, and anhydrous water having a surface area of 1 m ² /g was filled with 3.76 g of TiCl ₄ . 20 g of MgCl ₂ was sealed under N ₂ atmosphere and ground in a rotating ball mill for 6 hours. The rotation speed was 90r.pm. The Ti content of the ground product is 4.0 wt%;
The surface area was 50 m ² /g. The obtained solid catalyst component was designated as (a). Preparation of catalyst dispersion: Pour 300 milliliters of thoroughly degassed n-hexane into a 1-liter flask that has been sufficiently purged with nitrogen, then add 15.0 g of the solid component (a) described above.
Furthermore, diethylaluminum chloride and diethylaluminium ethoxide were added in a molar ratio of 3:1 for preactivation, so that the Al/Ti atomic ratio was 16. Next, sufficiently degassed and purified hexene-1 was added to adjust the hexene-1/Ti molar ratio to 20, and the mixture was stirred for 2 hours to obtain a fine catalyst suspension. This catalyst suspension was placed in a catalyst preparation tank with a stirrer that was purged with dry nitrogen, and then thoroughly degassed and purified.
- Add hexane to 25 liters to make the concentration of solid components 0.6 g/liter. catalyze this
(a) -1. High-pressure polymerization of ethylene Ethylene and butene-1 were copolymerized under the reaction conditions shown in Table 1 in a stirred autoclave-type continuous reactor with an internal volume of 1.5 liters. As the catalyst, the above-mentioned (a)-1 was used. In order to control the molecular weight of the resulting polymer, hydrogen was added as a chain transfer agent at the beginning of the polymerization. After reaching the target polymerization conditions, hydrogen supply was stopped and the lower limit of MFR of the polymer was confirmed. Ethylene, butene-1 and hydrogen were thoroughly degassed and purified before use. As a result of the polymerization, 13,800 g of polymer was obtained per 1 g of solid catalyst component. In other words, the catalyst yield (g・
PE/g・solid catalyst component)=13,800, and the yield per 1 g of Ti (g・PE/g・Ti)=345000. The MFR of the obtained polymer could be reduced to 0.05 (g/10 min). Examples 2 and 3 and Comparative Examples 1 and 2 Catalyst dispersion was carried out in the same manner as in Example 1, except that the composition of the mixture of organoaluminum compounds used in the preparation of the catalyst dispersion in Example 1 was changed as shown below. Solutions (a)-2 to (a)-5 were prepared.

[Table] Using the obtained catalyst dispersions (a)-2 to (a)-5,
Table 1 shows the results of copolymerization of ethylene and butene-1 in the same manner as in Example 1. As is clear from Table 1, when an alkyl aluminum alkoxide is used in combination as an organoaluminum compound, it has a great effect on lowering the MFR of the polymer.
If used in combination with 75 mol% or more, the catalytic activity will decrease significantly. Examples 4 to 6 and Comparative Examples 3 and 4 Catalysts were prepared in the same manner as in Example 1, except that the mixture of organoaluminum compounds used in the preparation of the catalyst dispersion in Example 1 and its composition were changed as shown below. Dispersions (a)-6 to (a)-10 were prepared.

[Table] Using the obtained catalyst dispersions (a)-6 to (a)-10,
Table 1 shows the results of copolymerization of ethylene and butene-1 in the same manner as in Example 1. As is clear from the table, when an organoaluminum compound and an alkylsiloxalane derivative are mixed and used in the ratio specified in the present invention, it is highly effective not only in significantly improving the catalytic activity but also in reducing the MFR of the obtained polymer. do. Example 7 Manufacture of catalyst component The catalyst component of Example 1 was manufactured in the same manner as in Example 1 except that Ti(OC ₄ H ₉ ) ₄ was used instead of TiCl ₄ , and the Ti content was 4.0. A solid catalyst component (b) was prepared having a surface area in weight percent of 50 m ² /g. Preparation of catalyst dispersion: Pour 300 milliliters of thoroughly degassed n-hexane into a 1-liter flask that has been sufficiently purged with nitrogen, then add 15.0 g of the solid component (b) from the previous procedure.
Furthermore, a mixture of diethylaluminum chloride and trimethyldiethylsiloxalane at a molar ratio of 3:1 was added for preactivation to increase the Al/Ti atomic ratio.
It was set at 16. Next, thoroughly degassed and purified hexene.
1 was added to adjust the molar ratio of hexene-1/Ti to 20, and the mixture was stirred for 2 hours to obtain a fine catalyst suspension. This catalyst suspension was placed in a catalyst preparation tank with a stirrer purged with dry nitrogen, and then thoroughly degassed and purified.
- Add hexane to 25 liters to give a solid concentration of 0.6 g/liter. catalyze this
(b) -1. High-pressure polymerization of ethylene High-pressure polymerization of ethylene was carried out in exactly the same manner as in Example 1, except that catalyst dispersion (b)-1 was used. The polymerization results are as shown in Table 1.1g of solid catalyst component
28800 g of polymer was obtained per batch. In other words, yield to catalyst (g・PE/g・solid catalyst component)=28800
So, yield per 1g of Ti (g・PE/g・Ti)=
It was 720,000. The MFR of the obtained polymer is 0.03
(g/10 minutes) or less. Example 8 Catalyst dispersion liquid (c)-1 was prepared in the same manner as in Example 7 except that the titanium compound was changed to TiCl ₃ in the production of the catalyst component in Example 7, and a co-polymer of ethylene and butene-1 was prepared. Polymerization was carried out. Table 1 shows the reaction conditions and polymerization results adopted. Examples 9 to 14 Same apparatus and catalyst dispersion as in Example 1 ((a)--
1) was used to carry out copolymerization of ethylene and other α-olefins. Table 2 shows the reaction conditions and polymerization results adopted. Examples 15 to 17 Same equipment and catalyst dispersion as in Example 4 ((a)--
6) was used to carry out copolymerization of ethylene and other α-olefins. Table 2 shows the reaction conditions and polymerization results adopted.

【table】

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a flowchart to help understand the technical contents of the present invention regarding Ziegler catalysts.

Claims (1)

[Claims] 1. Pressure exceeding 200 Kg/cm ² and at least 125
A process for polymerizing ethylene, characterized in that ethylene or ethylene and at least one other α-olefin are brought into contact with a catalyst consisting of a combination of components A and B as described below at a temperature of °C. Component A (1) General formula R ¹ _3-n AlX ¹ _n (where R ¹ is a carbon number of 1 to 10
hydrocarbon residue, X ¹ is halogen or hydrogen,
m is a number of 0≦m≦2) and the compound represented by the formula R ² _3-o Al(OR ³ ) _o (where R ²
and R ³ is a hydrocarbon residue having 1 to 10 carbon atoms, n
is a number of 1≦n≦2)
a mixture of organoaluminum compounds consisting of 75 to 1 mol %, or (2) general formula R ¹ _3-n AlX ¹ _n (where R ¹ is a carbon number of 1 to 10
hydrocarbon residue, X ¹ is halogen or hydrogen,
m is a number of 0≦m≦2) and 10 to 90 mol% of the compound represented by the formula (Here, R ⁴ to ^{R 8} are each a saturated hydrocarbon group having 1 to 10 carbon atoms or hydrogen, but R ⁸ is a halogen atom or It can also be a group represented by R ⁹ to ^{R 11} are each a saturated hydrocarbon group having 1 to 10 carbon atoms or hydrogen. ) A mixture of an organoaluminum compound and an alkylsiloxalane derivative, consisting of 90 to 10 mol% of the compound represented by: Component B: A solid product obtained by contacting a titanium compound in which titanium has a trivalent or tetravalent valence with magnesium dihalide (however, this magnesium dihalide has a surface area that decreases before or after contact with the titanium compound). is at least 5 m ² /g).