JPH06211927A - Solid catalyst component for production of polyethylene - Google Patents

Abstract

PURPOSE:To obtain catalyst component excellent in catalytic activity, reduced in fine dust content and useful for obtaining PE having a high bulk specific gravity by bringing diethoxymagnesium, tetrabutoxytitanium and an aromatic carboxylic acid ester into contact with each other under specified conditions, followed by specified treatment. CONSTITUTION:Diethoxymagnesium, tetrabutoxytitanium and an aromatic carboxylic acid ester (e.g. di-n-butyl phthalate) are brought into conatact with each other at 50-150 deg.C to form a homogeneous solution. The solution is brought into contact with AlCl3 and TiCl4 kept at 20 deg.C or lower and then reacted at 50-100 deg.C to give a solid product, which is washed with an inert hydrocarbon solvent (e.g. n-heptane), and then treated with TiCl4 at 40-130 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a solid catalyst used for polymerization in the production of general-purpose polyethylene widely used for various pipes, fuel tanks, containers, food packaging films and agricultural films and sheets. More specifically, the present invention relates to a solid catalyst component for producing polyethylene, which is capable of obtaining an ethylene polymer having a high catalytic activity, a small amount of fine powder, and a high bulk specific gravity.

[0002]

2. Description of the Related Art In recent years, solid catalyst components containing magnesium halide and titanium halide as essential constituents have been
Numerous proposals have been made for catalyst systems used in the production of polyethylene in combination with organoaluminum compounds. For example, Japanese Patent Publication No. 63-43407 and 63-
The solid catalyst component for polyethylene production disclosed in Japanese Patent Publication No. 49686 and Japanese Patent Publication No. 34484/1993 uses magnesium chloride as a magnesium compound and titanium halide as an active component as a main component. The polymer yield per component (hereinafter referred to as "catalytic activity") is improved. However, in these catalyst components, chlorine contained in magnesium chloride has various adverse effects on the produced polymer in the same manner as chlorine contained in titanium halides, and the effect of chlorine is practically negligible. There is a problem that the activity is required, or the concentration of magnesium chloride itself needs to be reduced.

On the other hand, a solid catalyst component having a composition in which a transition metal compound such as a titanium halogen compound is deposited or supported on a porous inorganic compound such as silica or alumina is disclosed in Japanese Patent Publication No.
It is disclosed in Japanese Laid-Open Patent Publication Nos. 1-26805 and 61-50964. The main purpose of these component systems is not to use magnesium chloride as a starting material, but also to obtain polyethylene with excellent particle characteristics. There is room for improvement.

[0004] In addition, in the production of polyethylene, it is a major issue to reduce the generation of fine powder polymer which causes phenomena such as plugging and dust explosion in the process operation. It is required to impart a function to the catalyst component to suppress the finely divided polymer. The present inventors have already developed a highly active solid catalyst component for producing polyethylene (JP-A-3-143906 and JP-A-3-157409), and have achieved excellent results, respectively. When contacting with organoaluminum, fine particles of 100 μm or less are generated,
Due to this, the above-mentioned problem that the bulk specific gravity of the produced polymer cannot be sufficiently increased has not been solved yet.

[0005]

In order to solve the problem of generation of fine powder during polymerization, a method of pre-contacting a solid catalyst component with an organoaluminum compound and ethylene (Japanese Patent Publication Nos. 1-53885 and 1-10532). However, if this method is applied, special equipment and equipment are required for pretreatment, and the operating process increases, resulting in cost increase. There is a shortcoming that is poor.

The present invention has been developed as a result of repeated research aimed at solving the problems of the prior art with respect to means for preparing a solid catalyst component, and its purpose is to maintain a high degree of catalytic activity. It is an object of the present invention to provide a solid catalyst component for producing polyethylene, which is capable of efficiently producing a polymer having a small amount of fine powder and a high bulk specific gravity.

[0007]

The solid catalyst component for producing polyethylene according to the present invention for achieving the above object comprises:
50 parts of (a) diethoxymagnesium, (b) tetrabutoxytitanium and (c) aromatic carboxylic acid ester
A uniform solution is formed by contacting in a temperature range of ˜150 ° C., and the uniform solution is contacted with (d) aluminum trichloride and (e) silicon tetrachloride kept at 20 ° C. or lower,
Then, the solid product obtained by reacting in a temperature range of 50 to 100 ° C. is washed with an inert hydrocarbon solvent,
Further, it is structurally characterized in that it is obtained by treating (f) titanium tetrachloride in a temperature range of 40 to 130 ° C.

(A) diethoxymagnesium [hereinafter sometimes simply referred to as "(a) substance"], (b) tetrabutoxytitanium [hereinafter sometimes simply referred to as "(b) substance"] and (c) aromatic A homogeneous solution of a carboxylic acid ester [hereinafter sometimes simply referred to as "(c) substance"] is mixed and contacted with these substance components in a temperature range of 50 to 150 ° C for 10 minutes or more, preferably 1 hour or more while stirring. To be formed.

At this time, the substance (c) used is
For example, aromatic carboxylic acid monoesters such as methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl benzoate, methyl toluate, ethyl toluate, and further dimethyl phthalate, diethyl phthalate, dipropyl phthalate. , Dibutylphthalate, diisobutylphthalate, diamylphthalate, diisoamylphthalate, ethylbutylphthalate, ethylisobutylphthalate, ethylpropylphthalate,
Aromatic dicarboxylic acid diesters such as isooctyl phthalate may be mentioned.

The amount ratio of each substance to be mixed is arbitrary, but usually 0.5 g of (b) substance to 1 g of (a) substance.
˜2.0 g, and (c) substance 0.01 to 1.0 g. In addition, the order of contact of each substance is not particularly limited, but usually (a) substance and (b) substance are contacted in advance to form a homogeneous solution, and then (c) substance is added, or (b) substance is added. A preferable procedure is the operation of bringing the substance (a) into contact with the substance (c) and then adding the substance (a). Since the formed homogeneous solution has a high viscosity, it can be diluted with an inert organic solvent such as hexane, heptane, toluene, xylene or the like in consideration of easiness of operation.

(A) to (c) formed as described above
A homogeneous solution of the substance is then kept at a temperature of 20 ° C. or lower (d) aluminum trichloride [hereinafter sometimes simply referred to as “(d) substance”] and (e) silicon tetrachloride [hereinafter simply referred to as “(e)”. Sometimes called "substance"],
Then, the temperature is raised to react to produce a solid product. The use ratio of the substance (d) and the substance (e) is arbitrary, but normally, the amount of the substance (d) is 0.
05-2.0 g, substance (e) is used in the range of 0.5-50 ml. Further, if necessary, the substances (d) to (e) can be diluted with an inert hydrocarbon solvent such as hexane, heptane, toluene, xylene, etc. before use.

The means of contact is a method of adding the above-mentioned homogeneous solution into the substances (d) and (e) which are maintained at a temperature of 20 ° C. or lower. At this time, the substances (d) and (e) It is necessary to add gradually while taking care to avoid a rapid reaction with the homogeneous solution. By this contact, fine solid particles are precipitated, but the (d) substance and (e)
When the temperature of the substance exceeds 20 ° C., the resulting polymer has a large amount of fine powder, and the bulk specific gravity is remarkably reduced. Therefore, it is indispensable to give sufficient consideration to maintain the above temperature range until the contact treatment is completed. The reaction after the deposition operation accompanying such contact is carried out in the temperature range of 50 to 100 ° C. If the reaction temperature is less than 50 ° C., the reaction does not proceed sufficiently, and if it exceeds 100 ° C., the evaporation of the solvent becomes remarkable, so that the reaction is difficult to control.

After the completion of the reaction, the obtained solid product was washed with an inert hydrocarbon solvent, and 40 (f) titanium tetrachloride (hereinafter sometimes referred to simply as "(f) substance") was used.
Process in the temperature range of ~ 130 ° C. If the treatment temperature is lower than 40 ° C., the performance of the solid catalyst component is not sufficiently imparted, and 13
When the temperature exceeds 0 ° C, the evaporation of the solvent becomes remarkable and the substance used is decomposed, which makes it difficult to control the contact treatment operation. The treatment time is appropriately determined within the range of 10 minutes to 100 hours, but is preferably set within the range of 30 minutes to 5 hours. The amount of the substance (f) used is not particularly limited, but is usually 1 ml or more, preferably 5 ml or more per 1 g of the substance (a). In addition, the substance (f) may be diluted with an inert hydrocarbon solvent such as hexane, heptane, toluene, xylene, etc., if necessary.

The solid catalyst component prepared by the above-mentioned process is washed with an inert organic solvent such as heptane, if necessary, and the solid catalyst component for producing polyethylene of the present invention is obtained by directly or drying.

The solid catalyst component for producing polyethylene according to the present invention is used as a practical polymerization catalyst in combination with an organoaluminum compound. The organoaluminum compound used at this time is represented by the general formula R _n AlX _3-n (wherein R is a hydrocarbon group and X is a halogen atom 1 ≦ n ≦ 3). Specific examples include triethylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride and the like, and one kind or a mixture of two or more kinds is used.

The amount of the organoaluminum compound used in forming the polymerization catalyst is in the range of 1 to 1000 in terms of molar ratio per mole of titanium atom in the solid catalyst component. The polymerization temperature is set to 0 to 150 ° C., and the polymerization pressure is set to 0 to 100 kg / cm ² · G. At this time, hydrogen can be used as an auxiliary as a molecular weight modifier, and an olefin having 3 or more carbon atoms can be used as a comonomer for polymerization. If necessary, an electron-donating compound such as an ester, a ketone, an amine, and a silicon compound having a Si—O—C bond can be added and used.

[0017]

When ethylene is polymerized using the solid catalyst component of the present invention, a high catalytic activity is exhibited, and the activity is stably maintained for a long time. Further, even if the polyethylene is directly contacted with an organoaluminum compound at a high temperature for polymerization, polyethylene having a small amount of fine powder and a high bulk specific gravity can be produced.

In addition, by using the solid catalyst component of the present invention, excellent effects such as the effect of chlorine on the produced polymer is small and polyethylene having a uniform molecular weight distribution with little intervening low molecular weight polymer can be obtained are exhibited. It

[0019]

EXAMPLES The present invention will be described in more detail below by comparing Examples and Comparative Examples.

Example 1 Preparation of solid catalyst component: 100 g of diethoxymagnesium and 124 ml of tetrabutoxytitanium were placed in a round bottom flask (capacity 2 l) equipped with a stirrer whose inside was sufficiently replaced with nitrogen gas.
Was charged and treated at 130 ° C. for 6 hours with stirring to obtain a highly viscous homogeneous solution. After the solution was cooled to 90 ° C, 800 ml of toluene preheated to 90 ° C was added, and further 50 ml of di-n-butyl phthalate was added to 90 ° C.
The mixture was stirred for 1 hour while maintaining the temperature. By this operation, each substance added was completely dissolved, and a colorless transparent uniform solution was obtained. Separately, a 500 ml round bottom flask equipped with a stirrer was charged with 5 g of aluminum trichloride, 20 ml of silicon tetrachloride and 50 ml of n-heptane and cooled to 0 ° C. 45 ml of the above homogeneous solution was added dropwise thereto over 1 hour while maintaining the temperature in the system at 0 ° C. Then 1
The temperature was raised to 55 ° C. over time, and the reaction was carried out for 1 hour to obtain a solid product. The solid product obtained was washed 5 times with 200 ml of n-heptane at 40 ° C., the supernatant liquid was removed, and then 40 ml of toluene and 20 ml of titanium tetrachloride were charged to obtain 100.
It was treated at a temperature of ° C for 2 hours. Finally, it was washed 7 times with 100 ml of 40 ° C. n-heptane to obtain about 10 g of a solid catalyst component. The titanium content in this solid catalyst component was 1.5% by weight.

Ethylene polymerization; 700 ml of n-heptane was charged into an autoclave (stainless steel) with a stirrer having an inner volume of 1500 ml, which was completely replaced with nitrogen gas, and triethylaluminum 1.00 mm while keeping it under a nitrogen gas atmosphere.
Charged ol. Then, after raising the temperature to 90 ° C., 0.01 mmol of the solid catalyst component as titanium atom was charged, hydrogen was charged so that the pressure in the system became 3 kg / cm ² · G, and the total pressure of ethylene was changed. ² while feeding so that it becomes 7 kg / cm ² · G
Polymerization was carried out for a period of time. The obtained slurry polymer was filtered and dried under reduced pressure to obtain 322 g of polyethylene powder. At this time, the catalyst activity was 12200 g / g-cat. As the polymer yield per 1 g of the catalyst component in the polymerization time of 2 hours. The bulk specific gravity of the obtained polymer was 0.41 g / cm ³ , and the fine powder of 100 μm or less was 0.5 wt%.

Example 2 A solid catalyst component was prepared in the same manner as in Example 1 except that di-i-octyl phthalate was used instead of di-n-butyl phthalate. An ethylene polymerization test was conducted in the same manner as in Example 1 using this solid catalyst component.
The results shown in are obtained.

Example 3 100 g of diethoxymagnesium was placed in a round bottom flask (capacity: 2 l) equipped with a stirrer whose interior was sufficiently replaced with nitrogen gas.
And 124 ml of tetrabutoxy titanium were charged and treated at 130 ° C. for 6 hours with stirring to obtain a highly viscous homogeneous solution.
After cooling the solution to 90 ° C., 800 ml of toluene preheated to 90 ° C. was added, and ethyl benzoate 50 was added.
ml was added and the mixture was stirred for 1 hour while maintaining the temperature of 90 ° C. By this operation, each substance was completely dissolved and a colorless transparent uniform solution was obtained. A 45 ml round bottom flask with a stirrer (500 ml) was prepared by separating 45 ml of the obtained homogeneous solution.
Then, add 2 g of aluminum trichloride into it, and add 9
After treating at 0 ° C for 1 hour, the mixture was cooled to 0 ° C. Then n
100 ml of heptane was charged, and 40 ml of silicon tetrachloride was charged while keeping the temperature in the system at 0 ° C. Then, the temperature was raised to 55 ° C. over 1 hour, and the reaction was performed for 1 hour to obtain a solid product. The solid product obtained was treated with n-heptane 2 at 40 ° C.
After washing 5 times with 00 ml and removing the supernatant liquid, 40 ml of toluene and 20 ml of titanium tetrachloride were charged and the temperature was 100 ° C.
At a temperature of 2 hours. Finally, it was washed 7 times with 100 ml of 40 ° C. n-heptane to obtain about 10 g of a solid catalyst component. An ethylene polymerization test was conducted in the same manner as in Example 1 using this solid catalyst component, and the results shown in Table 1 were obtained together.

Comparative Example 1 A solid catalyst component was prepared in the same manner as in Example 1 except that di-n-butyl phthalate was not used, and an ethylene polymerization test was conducted in the same manner as in Example 1. The obtained results are also shown in Table 1.

[0025]

[Table 1]

[0026]

As described above, when ethylene polymerization is carried out using the solid catalyst component for producing polyethylene according to the present invention, a sufficiently high catalytic activity is continuously exhibited and deterioration is caused even in a long-term polymerization reaction. A small amount of stable catalytic performance is exhibited. Further, it becomes possible to obtain polyethylene having a small amount of fine powder and a high bulk specific gravity without the need for adding a step such as pretreatment with organic aluminum and ethylene. Furthermore, not only per unit catalyst component,
Since the catalytic activity per unit weight of the transition metal component is also extremely high, the effect of chlorine on the produced polymer can be reduced to the extent that no deashing step is required.

In addition, since the polyethylene obtained by using the solid catalyst component of the present invention has a narrow molecular weight distribution, there is an advantage that the production of a low molecular weight polymer which is a problem in process operation can be suppressed as much as possible. Also, there is little loss of the raw material magnesium compound in the catalyst preparation step,
In addition to being able to use industrially inexpensive raw materials, since the fluidity of the catalyst particles is good, the sedimentation rate during the washing operation is fast, and it is possible to efficiently carry out powder transportation after drying. There are handling and economic benefits.

[Brief description of drawings]

FIG. 1 is a flow chart showing steps for preparing a solid catalyst component in the present invention.

Claims (1)

[Claims] 1. (a) Diethoxymagnesium, (b)
A uniform solution was formed by contacting tetrabutoxy titanium and (c) an aromatic carboxylic acid ester in a temperature range of 50 to 150 ° C., and the uniform solution was kept at 20 ° C. or lower (d) aluminum trichloride and ( e) The solid product obtained by contacting with silicon tetrachloride and then reacting in the temperature range of 50 to 100 ° C. is washed with an inert hydrocarbon solvent, and then (f) titanium tetrachloride is added to 40
A solid catalyst component for producing polyethylene, which is obtained by treating in a temperature range of 130 ° C.