JPS6228162B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyethylene, and more particularly to a method for highly active polymerization of polyethylene using a modified magnesium halide as a catalyst carrier. It is well known that magnesium halides are used as carrier raw materials for supporting transition metals in conventional high-activity polymerization catalysts for polyolefins.
It has been found that when a transition metal is directly supported on this, the amount supported is very small and the activity is not very high. Furthermore, various proposals have been made to overcome this drawback, such as pre-treatment before contact with transition metals, or the presence of various compounds during reaction with transition metals. For example, those made from magnesium halide electron donor adducts produced by coordinating an electron donor such as water, alcohol, or ester to magnesium halide (Japanese Patent Publication No. 46-34092, Japanese Patent Publication No. 34092,
48-19794), those in which a silicon compound is reacted with an adduct of a halogenated magnesium electron-donating compound (Japanese Patent Publication No. 1796-1983, JP-A-49-88983)
(No. 47-41676), those using activated anhydrous magnesium halides obtained by activation using a ball mill, etc. or by heating alcohol and water adducts (Japanese Patent Publication No. 47-41676), alcohol pretreatment of magnesium dihalides A method in which a substance is reacted with an organic metal of Groups 1 to 3 of the periodic table (Japanese Patent Application Laid-Open No. 119980/1982), and a method in which magnesium dihalide and aluminum chloride are co-precipitated from an alcohol solution (Japanese Patent Application Laid-Open No. 1130692/1972) Public bulletin) is known. However, the method of pre-treating with an electron donor to form an adduct requires a great deal of care and effort in adjusting the amount of addition and other treatments.
In addition, further processing of these materials increases the number of steps, and even if the amount of titanium supported increases, the activity may decrease or the bulk specific gravity of the resulting polyethylene may be low.All methods have advantages and disadvantages. ing. In the process of conducting detailed studies on highly active polymerization of ethylene using magnesium chloride, the present inventors decided to bring titanium halide onto the magnesium chloride after contacting it with a specific amount of a halogen-containing titanium compound and alcohol. As a result, they discovered the fact that the activity increases dramatically and the bulk specific gravity of polyethylene also increases, leading to the completion of the present invention.
That is, the present invention provides a method for producing polyethylene using a catalyst containing (A) a reaction product of a magnesium compound and a titanium halide and (B) an organoaluminum compound, in which 0.1 to 2% of magnesium chloride is used as the component (A). Production of polyethylene characterized by using a solid product obtained by causing a contact reaction with twice the molar amount of a halogen-containing tetravalent titanium compound and 0.1 times the molar amount or more of alcohol, and then reacting the produced solid substance with a titanium halide. The present invention provides a method. As the magnesium chloride used in the present invention, unactivated magnesium chloride such as commercially available anhydrous magnesium chloride is sufficient, but it is of course possible to use anhydrous magnesium chloride activated by a conventionally known method. Furthermore, a mixture with a known metal compound carrier that does not inhibit ethylene polymerization may be used. The component (A) in the catalyst used in the method of the present invention is adjusted as follows. That is, the magnesium chloride described above is usually first dispersed in an inert solvent. In this case, the amount of magnesium chloride dispersed is not particularly limited, but for convenience of operation, it is 50 to 500 g per solvent.
It is preferable that Subsequently, a halogen-containing tetravalent titanium compound and alcohol are added to this dispersion system and reacted at a predetermined temperature and time with stirring to modify the magnesium chloride. It is efficient to set the reaction temperature at this time to usually 0 to 150℃, especially 50 to 100℃, and the polymerization activity of the resulting catalyst is high, and the bulk specific gravity of polyethylene produced using this catalyst is also high. preferable. Although the reaction time depends on the reaction temperature, it is usually 5 minutes to 5 hours, preferably 0.5 to 3 hours.
It's time. The order in which the three components are brought into contact in this reaction is not particularly limited to this, and may be divided into two stages, such as first reacting magnesium chloride and a halogen-containing tetravalent titanium compound, and then adding alcohol to the reaction system. You may do so. The halogen _- containing tetravalent titanium compound used in the above reaction has the general formula: indicates an integer. ] Compounds represented by these are preferred. Examples of the halogen-containing tetravalent titanium compound include titanium tetrahalide,
Examples of the alkoxy titanium halide include TiCl ₄ , TiBr ₄ , CH ₃ OTiCl ₃ , (C ₂ H ₅ O) ₂ TiCl ₂ and the like. Among these, highly halogen-containing materials, especially titanium tetrachloride (TiCl ₄ ), are most preferred. The amount of the halogen-containing tetravalent titanium compound added is 0.1 to 2 times the molar amount of the above magnesium chloride. In this case, it is preferable to use an amount such that the amount of halogen atoms contained in the titanium compound is 0.5 times or more by mole relative to the amount of the magnesium compound. The amount of the above titanium compound added is based on magnesium chloride.
If the amount is less than 0.1 times the molar amount, the activity of the catalyst and the bulk specific gravity of the produced polymer will not be sufficiently improved. Furthermore, when a large amount of a halogen-containing tetravalent titanium compound is used, a large amount of titanium is supported in the modified product at this stage as in the past, and no improvement in polymerization activity is observed, rather the bulk specific gravity of the resulting polymer is low. This also results in waste of the reactant, so the amount used is not more than twice the molar amount, preferably not more than the equivalent molar amount, of magnesium chloride. On the other hand, the alcohol used in the above-mentioned reaction is a linear or side chain aliphatic or alicyclic alcohol, and a primary or secondary alcohol having 1 to 6 carbon atoms is particularly preferred. Specifically, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, amyl alcohol,
Examples include octanol. The amount of alcohol added is based on the above magnesium chloride.
The amount should be 0.1 times the molar amount or more, preferably 0.5 times the molar amount or more. There is no particular restriction on the upper limit of the amount to be added, but since using a large amount will result in waste of the titanium compound as described below, the amount is usually around the same amount as the halogen contained in the titanium compound. If the amount of alcohol used is lower than this lower limit, the desired improvement in polymerization activity or bulk specific gravity of the polymer cannot be sufficiently expected. Furthermore, the solvent used in the above reaction is not particularly limited as long as it is inert and does not react with the above-mentioned magnesium chloride, halogen-containing tetravalent titanium compound, and alcohol. Examples include solvents. Specifically, butane, pentane, hexane, heptane, cyclohexane, etc. are suitable. Although the reaction using a solvent as described above is a preferred embodiment of the present invention, it is also possible to carry out the reaction without a solvent. In this case, for example, a predetermined ratio of the magnesium chloride, halogen-containing tetravalent titanium compound, and alcohol may be mixed and reacted directly mechanically using a ball mill or the like. The modified magnesium chloride solid material thus obtained is used in the next reaction either in the reaction dispersion as it is or after washing and separating the modified solid. Note that the modified product may be further treated with an organoaluminum compound and used in the next reaction. Component (A) in the catalyst used in the method of the present invention is a solid product obtained by further reacting the above-mentioned modified magnesium chloride with a titanium halide. The titanium halides that can be used here include tetravalent, trivalent, and divalent halogen-containing titanium, specifically TiCl ₄ , TiBr ₄ , Ti(OR')Cl ₃ ,
Ti(OR′) ₂ Cl ₂ , Ti(OR′) ₃ Cl, TiCl ₃ , TiBr ₃ ,
Examples include TiCl ₂ (where R' represents an alkyl group), and those that do not contain a large amount of alkoxy groups are particularly preferred. The reaction between the modified magnesium chloride and the titanium halide is usually carried out in a hydrocarbon solvent, but it can also be carried out without a solvent, and any commonly employed contact method may be used. When carried out in a solvent,
A predetermined amount of titanium halide is added directly to the reaction solution for producing a modified product by the solvent method, or after the modified product is dispersed in an inert solvent again when a treatment such as washing and separation of the reaction solid is performed. The mixed dispersion thus obtained is heated to a temperature of 30 to 200 at normal pressure or under pressure.
The reaction is stirred and reacted at a temperature of 10 minutes to 5 hours, preferably 0.5 to 3 hours at a temperature of 50 to 150 degrees Celsius. On the other hand, in the case of a solventless reaction, mechanical mixing using a ball mill or the like may be performed at the above temperature and time. The proportion of titanium halide added in the above reaction is usually at least the equivalent molar amount, preferably in excess, relative to the amount of magnesium chloride used. Specifically 1
~20 times the molar amount, preferably 2 to 15 times the molar amount, and in particular, when using the modified product pretreatment solution as it is and unreacted alcohol and free titanium compounds are present in the solution, it is in large excess with respect to these. Specifically, it is preferable to use as a guideline approximately 5 times or more the molar amount of the halogen-containing titanium compound originally used. If the amount of titanium halide used is small, the resulting polyethylene will not have sufficient bulk specific gravity or polymerization activity. After carrying out the above reaction, solid components are separated and washed from the reaction product. At this time, the number of carbon atoms for cleaning is 5 or more.
10 inert hydrocarbon solvents such as pentane, hexane, cyclohexane, heptane, etc. The washed solid product is further dispersed in an inert hydrocarbon solvent in an inert gas at an appropriate concentration and used as a catalyst component. Note that the solid product after washing may be further treated with organoaluminum and then made into a dispersion as described above. In this case, the polymerization activity of the catalyst and the bulk specific gravity of the polyethylene to be polymerized are further increased. The organoaluminum compound that can be used in this case may be the same as the organoaluminum compound as the catalyst component (B) described later, or may be different. It is sufficient that the amount used is approximately equal to or more than the amount of supported titanium. The method of the present invention uses a reaction product of the above-mentioned modified magnesium chloride and the above-mentioned titanium halide.
This is carried out using a catalyst consisting of both components (A) and (B), with component (A) and organoaluminum compound as component (B).
In polymerizing ethylene, a dispersion of component (A) and an organic aluminum compound as component (B) are added as catalysts to the reaction system, and then ethylene is introduced into the system. The polymerization method and conditions are not particularly limited, and any of solution polymerization, suspension polymerization, gas phase polymerization, etc. is possible, and both continuous polymerization and discontinuous polymerization are possible. For example, in the case of solution polymerization or suspension polymerization, the amount of catalyst components added is usually 0.001 to 5 mmol of component (A), while the amount of component (B) added is 10 to 500 mmol per component (A). (molar ratio), preferably 20 to 300 (molar ratio). In addition, the ethylene pressure in the reaction system is usually normal pressure to 100Kg/cm ² , preferably 2
~20Kg/ ^cm2 , reaction temperature is usually 50~180℃,
Preferably the temperature is 60-100℃, and the reaction time is usually 0.5-5.
time, preferably 1 to 3 hours. Molecular weight adjustment during polymerization can be carried out by known means, such as hydrogen. The organoaluminum compound which is the component (B) of the catalyst used in the method of the present invention has the general formula
R″mAlCl _3-n [In the formula, R″ represents an alkyl group having 1 to 8 carbon atoms, and m represents 1 to 3. ] are preferred; representative examples include trialkylaluminum compounds such as trimethylaluminum, triethylaluminum, triisopropylaluminium, triisobutylaluminum, trioctylaluminum, diethylaluminum monochloride, diisopropylaluminum monochloride, diisobutyl Examples include dialkyl aluminum monohalides such as aluminum monochloride and dioctyl aluminum monochloride. The types of polyethylene that can be polymerized by the method of the present invention include not only ethylene homopolymers but also copolymers of ethylene and small amounts of α-olefins such as propylene, butene-1, hexene-1, and the like. Note that the catalyst used in the method of the present invention may further contain an organic metal such as organic zinc. According to the method of the present invention as described above, although its actual nature is unknown, an effective carrier is formed by a complex reaction among the halogen-containing tetravalent titanium compound, alcohol, and magnesium chloride in the modification step, Furthermore, as a result of the effective support of titanium on the modified product, high polymerization activity is exhibited, and polyethylene with a high bulk specific gravity can be obtained. Therefore, by the method of the present invention, high-density polyethylene of high quality and high bulk specific gravity can be produced extremely efficiently and economically. Next, the method of the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of normal heptane, 5.3 mmol of TiCl ₄ and 21 mmol of ethanol were added, and the temperature was raised to 80 mmol.
The reaction was carried out at ℃ for 1 hour. Then, 45 mmol of TiCl ₄ was added, and the mixture was reacted under reflux (98° C.) for 3 hours. After cooling, the supernatant liquid was removed by decanting.
Another 100 ml of n-heptane was added, and the washing operation of stirring, standing still, and removing the supernatant liquid was repeated three times. Finally, 200 ml of normal heptane was added to obtain a dispersion of the catalyst solid component (A). The amount of titanium supported was determined by a colorimetric method and was 37 mgTi/g-carrier. (2) Polymerization of ethylene Thoroughly dry the autoclave from step 1, and add a slurry of 400 ml of n-hexane, 2.0 mmol of triethylaluminum, and the above catalyst solid component (A) under an argon stream to 0.01 titanium atoms.
A millimole equivalent amount was introduced and the temperature was raised to 80°C. Next, polymerization was carried out at 80° C. for 1 hour while continuously supplying ethylene at a hydrogen pressure of 3 kg/cm ² and an ethylene pressure of 5 kg/cm ² . Remove unreacted gases and separate the polymer,
After drying, 126 g of white polyethylene was obtained. Polymerization activity is per gram of titanium atom per hour.
263Kg, the melt index of polyethylene is 3.30 (190℃, 2.16Kg load), and the bulk specific gravity is
It was 0.28. Comparative Example 1 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of n-heptane, and 21 mmol of ethanol was added to this.
After adding mmol of the mixture, the temperature was raised and the reaction was carried out at 80°C for 1 hour. Then add 45 mmol of TiCl ₄ at 98 °C.
The mixture was allowed to react for 3 hours. A solid catalyst component was produced in the same manner as in Example 1 (1). The amount of titanium supported at this time was 172 mg-/Ti/g-support. (2) Ethylene polymerization The same procedure as in Example 1 (2) was carried out except that the solid catalyst component produced in (1) above was used. Polymerization of ethylene was carried out. As a result, 45 g of polyethylene was obtained. The polymerization activity is 94 kg per gram of titanium atom per hour, the melt index of polyethylene is 3.8 (190℃, 2.16 kg load), and the bulk specific gravity is
It was 0.19. Comparative Example 2 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of n-heptane, 45 mmol of TiCl ₄ and 10.5 mmol of ethanol were added, and the temperature was raised.
The reaction was carried out at 98°C for 3 hours. The following is Example 1
A solid catalyst component was produced in the same manner as in (1). The amount of titanium supported at this time was 90 mg-Ti/g-support. (2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component produced in the above (1) was used in an amount equivalent to 0.02 mmol of titanium atoms. As a result, 23 g of polyethylene was obtained. The polymerization activity is 24 kg per gram of titanium atom per hour, the melt index of polyethylene is 0.53 (190℃, 2.16 kg load), and the bulk specific gravity is
It was 0.20. Comparative Example 3 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of normal heptane, 5.3 mmol of SiCl ₄ and 21 mmol of ethanol were added, and the temperature was raised to 80 mmol.
The reaction was carried out at ℃ for 1 hour. Next, 45 mmol of TiCl ₄ was added and reacted at 98° C. for 3 hours. A solid catalyst component was produced in the same manner as in Example 1 (1). The amount of titanium supported at this time was 35mg-Ti/g
- It was a carrier. (2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component produced in the above (1) was used in an amount equivalent to 0.02 mmol of titanium atoms. As a result, 107 g of polyethylene was obtained. The polymerization activity was 112 kg per gram of titanium atom per hour, the polyethylene melt index was 2.5 (190°C, 2.16 kg load), and the bulk specific gravity was 0.26. Comparative Example 4 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of n-heptane, 5.3 mmol of VCl ₄ and 21 mmol of ethanol were added thereto, the temperature was raised, and the reaction was carried out at 80° C. for 1 hour. then
45 mmol of TiCl ₄ was added and reacted at 98°C for 3 hours. Thereafter, a washing operation was performed in the same manner as in Example 1 (1) to produce a solid catalyst component. The amount of titanium supported at this time was 115 mg-Ti/g-support. (2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component produced in the above (1) was used in an amount equivalent to 0.02 mmol of titanium atoms. As a result, 8 g of polyethylene was obtained. The polymerization activity was 8 kg per gram of titanium atom per hour. Comparative Example 5 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of n-heptane, 5.3 mmol of tetraisopropoxytitanium (Ti(i-PrO) ₄ ) was added, and the temperature was raised to 80°C for 1 hour. The reaction was carried out. Next, 45 mmol of TiCl ₄ was added and reacted at 98° C. for 3 hours. The following washing operation was carried out in the same manner as in Example 1 (1) to produce a solid catalyst component. The amount of titanium supported at this time was 122 mg-Ti/g-support. (2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component prepared in (1) above was used in an amount equivalent to 0.02 mmol of titanium atoms. As a result, 40 g of polyethylene was obtained. The polymerization activity is 42 kg per gram of titanium atom per hour, the melt index of polyethylene is 0.74 (190℃, 2.16 kg load), and the bulk specific gravity is
It was 0.15. Examples 2 to 5 A solid catalyst component was produced and ethylene was polymerized in the same manner as in Example 1, except that the amounts of TiCl ₄ and ethanol used in the magnesium chloride modification step were changed. The results are shown in Table 1.

[Table] Example 6 (1) Production of catalyst 10.5 mmol of anhydrous magnesium chloride was suspended in 50 ml of n-heptane, 5.3 mmol of TiCl ₄ and 21 mmol of ethanol were added, and the temperature was raised to 80 mmol.
The reaction was carried out at ℃ for 1 hour. Then, cool to room temperature, remove the supernatant, and add 100 ml of n-heptane.
The dispersion was washed once with water, and 50 ml of n-heptane was added thereto to prepare a dispersion. 45 mmol of TiCl ₄ was added to this dispersion and reacted at 98° C. for 3 hours. A solid catalyst component was produced in the same manner as in Example 1 (1). The amount of titanium supported at this time was 25mg-Ti/g
- It was a carrier. (2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component produced in (1) above was used. As a result, 99 g of polyethylene was obtained. The polymerization activity was 206 kg per gram of titanium atom per hour, the polyethylene melt index was 1.66 (190°C, 2.16 kg load), and the bulk specific gravity was 0.27. Examples 7 and 8 The production of a solid catalyst component and the polymerization of ethylene were carried out in the same manner as in Example 1, except that isopropanol or n-butanol was used in place of ethanol. The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1. A method for producing polyethylene using a catalyst containing (A) a reaction product of a magnesium compound and a titanium halide and (B) an organoaluminum compound, wherein magnesium chloride is used as the component (A). of
It is characterized by using a solid product obtained by causing a contact reaction with a halogen-containing tetravalent titanium compound in an amount of 0.1 to 2 times the mole and an alcohol in an amount of 0.1 times the mole or more, and then reacting the generated solid substance with a titanium halide. Method of manufacturing polyethylene. 2 The halogen-containing tetravalent titanium compound has the general formula
XnTi(OR) _4-o [In the formula, X is a halogen atom, R is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 4. ] The method according to claim 1, wherein the compound is a compound represented by: 3. The method according to claim 1, wherein the halogen-containing tetravalent titanium compound is titanium tetrachloride.