JPH06179711A - Solid catalyst component for producing polyethylene - Google Patents

Abstract

PURPOSE:To provide the solid catalyst component highly actively acting on the polymerization of ethylene, giving polyethylene reduced in fine powder and narrow in its particle distribution, and used for the production of the polyethylene. CONSTITUTION:The solid catalyst component is prepared by heating and mixing diethoxy magnesium, tetrabutoxy titanium, an aromatic carboxylate ester and polystyrene, bringing the formed homogeneous solution into contact with a silicon tetrachloride held at <=20 deg.C, reacting the compounds at 50-100 deg.C, washing the obtained solid product with an active hydrocarbon solvent, and further treating the solid product with titanium tetrachloride 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 has a high catalytic activity, a small amount of fine powder, and an ethylene polymer having a narrow particle size distribution.

[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. There is a demand for the catalyst component to have a function of suppressing finely divided polymers and narrowing the particle size distribution of the produced polymers. The present inventors have already developed a highly active solid catalyst component for producing polyethylene (JP-A-3-143906 and JP-A-3-157409).
Japanese Patent Publication No.), each of which has achieved excellent results.
The above-mentioned problem that fine powder having a particle size of μm or less is generated and the particle size distribution of the produced polymer cannot be narrowed sufficiently due to this is still unsolved.

[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 narrow particle size distribution.

[0007]

The solid catalyst component for producing polyethylene according to the present invention for achieving the above object comprises:
(A) diethoxymagnesium, (b) tetrabutoxytitanium, (c) aromatic carboxylic acid ester, and (d)
A uniform solution is formed by contacting polystyrene in a temperature range of 50 to 150 ° C., and the uniform solution is contacted with (e) silicon tetrachloride kept at 20 ° C. or lower, and then 50 to 50 ° C.
The solid product obtained by the reaction in the temperature range of 100 ° C. is washed with an inert hydrocarbon solvent, and then (f)
The structural feature is that it is obtained by treatment with titanium tetrachloride in the 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"], (c) aromatic A homogeneous solution of a carboxylic acid ester [hereinafter sometimes simply referred to as "(c) substance"] and (d) polystyrene [hereinafter sometimes simply referred to as "(d) substance"] can be prepared by stirring these substance components with stirring.
It is formed by mixing and contacting for 10 minutes or more, preferably for 1 hour or more in the temperature range of 150 ° C.

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, (c) substance 0.01 to 1.0 g, and (d) substance 0.01 to 0.5 g. Further, there is no particular restriction on the order of contacting each substance, but it is preferable to contact the substances (a) and (b) in advance to form a uniform solution, and then add the substances (c) and (d). It is preferable as an operation procedure. 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 (d) formed as described above
The homogeneous solution of the substance is then brought into contact with (e) silicon tetrachloride (hereinafter sometimes referred to simply as "(e) substance") kept at a temperature of 20 ° C. or lower, and reacted to produce a solid product. . The proportion of the substance (e) used is arbitrary, but usually 0.5 g of the substance (e) per 1 g of the substance (a).
Used in the range of ~ 50 ml. In addition, the substance (e) can be diluted with an inert hydrocarbon solvent such as hexane, heptane, toluene, xylene, etc., if necessary.

The contacting means is preferably a method of adding the homogeneous solution into the substance (e) which is kept at a temperature of 20 ° C. or lower. When contacting, fine solid particles are precipitated, but when the temperature of the substance (e) exceeds 20 ° C., the obtained polymer does not show a narrow particle size distribution, and the bulk specific gravity is remarkably lowered. The reaction after the precipitation operation is performed 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. Although the reaction is accompanied by heat generation, it is desirable that the operation at the time of contact is carried out gradually while suppressing a rapid reaction.

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. 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 process is washed with an inert organic solvent such as heptane, if necessary, and is then dried or dried to obtain the solid catalyst component for producing polyethylene of the present invention.

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, it exhibits a high polymerization activity, and the activity is stable and long-lasting. Further, even if the organoaluminum compound is directly contacted at a high temperature for polymerization, polyethylene having a small amount of fine powder and a narrow particle size distribution can be produced. Therefore, it is possible to effectively suppress the generation of the finely divided polymer without requiring any additional step means such as pretreatment with an organoaluminum compound and ethylene, and at the same time, adjust the particle size distribution of the produced polyethylene to a narrow range. Is possible.

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 cooling the solution to 90 ° C., 800 ml of toluene preheated to 90 ° C. was added, 50 ml of di-n-butyl phthalate and 2 g of polystyrene were added, and the mixture was stirred for 1 hour while maintaining the temperature of 90 ° C. This operation completely dissolves the polystyrene,
A colorless transparent homogeneous solution was obtained. Separately, in a 500 ml round bottom flask equipped with a stirrer, silicon tetrachloride 40
ml and n-heptane 100 ml were charged and cooled to 0 ° C. 90 ml of the above homogeneous solution was added dropwise thereto over 1 hour while maintaining 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 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 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. The titanium content in this solid catalyst component was 4.2% 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 195 g of polyethylene powder. At this time, the catalyst activity was 17100 g / g-cat. As the polymer yield per 1 g of the catalyst component in the polymerization time of 2 hours. The average particle size of the obtained polymer is 450 μm, and the breadth of the particle size distribution is SP
AN [(Dp90-Dp10) / Dp50, where Dp
The value was 0.6 when x is the polymer particle diameter at cumulative weight x wt%]. The fine powder having a particle size of 100 μm or less was 0 wt% and the bulk specific gravity was 0.37.

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 A solid catalyst component was prepared in the same manner as in Example 1 except that di-i-propyl 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 4 A solid was prepared in the same manner as in Example 1 except that ethyl benzoate was used instead of di-n-butyl phthalate and the temperature at which the homogeneous solution and silicon tetrachloride were contacted was set to -20 ° C. A catalyst component was prepared. Example 1 using this solid catalyst component
When an ethylene polymerization test was conducted in the same manner as in, the results shown in Table 1 were obtained.

Comparative Example 1 A solid catalyst component was prepared in the same manner as in Example 1 except that di-n-butyl phthalate and polystyrene were 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.

Comparative Example 2 A solid catalyst component was prepared in the same manner as in Example 1 except that the temperature at which the homogeneous solution was brought into contact with silicon tetrachloride was 35 ° C., and an ethylene polymerization test was conducted in the same manner as in Example 1. .
The obtained results are also shown in Table 1.

[0027]

[Table 1]

[0028]

Industrial Applicability As described above, when ethylene is polymerized using the solid catalyst component for producing polyethylene according to the present invention, sufficiently high catalytic activity is continuously exhibited, so that it deteriorates even in a long-term polymerization reaction. Stable catalytic performance is exhibited. Further, it becomes possible to obtain polyethylene having a small amount of fine powder and a narrow particle size distribution without the need for adding a step such as pretreatment with organic aluminum and ethylene. Furthermore, 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 bringing tetrabutoxytitanium, (c) aromatic carboxylic acid ester and (d) polystyrene into contact with each other in a temperature range of 50 to 150 ° C., and the uniform solution was kept at 20 ° C. or lower (e) four. The solid product obtained by contacting with silicon chloride 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 used at 40 to 130 ° C.
A solid catalyst component for producing polyethylene, which is obtained by treating in a temperature range of 1.