JPH06211926A - Solid catalyst component for production of ultrahigh-molecular-weight polyethylene - Google Patents

Abstract

PURPOSE:To provide a solid catalyst component which, when used for the polymerization of ethylene, acts very actively to give a high yield of an ultrahigh- molecular-weight polyethylene having a small particle diameter, a narrow particle size distribution and a high bulk density. CONSTITUTION:A homogeneous solution obtained by heat mixing diethoxymagnesium with tetrabutoxytitanium is brought into contact with silicon tetrachloride and an aromatic carboxylic acid diester in a temperature region from -20 deg.C to 10 deg.C in the presence of an inert organic solvent, and the temperature is then raised to effect a reaction at a temperature of 40 deg.C or higher and lower than the boiling point of the organic solvent, thus producing a finely divided solid composition. This composition is brought into contact with titanium tetrachloride in the presence of a sorbitan ester of a fatty acid, then mixed with an aromatic carboxylic acid diester, and treated in a temperature region from 40 to 130 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has an average molecular weight of about 2,000,000 or more and a particle size of 100 to 250 when subjected to ethylene polymerization.
The present invention relates to a solid catalyst component for producing ultra-high molecular weight polyethylene, which can obtain ultra-high molecular weight polyethylene with a small size of micron, narrow particle size distribution and high bulk density in high yield.

[0002]

2. Description of the Related Art Ultra high molecular weight polyethylene has impact resistance,
Since it has excellent wear resistance, chemical resistance, and self-lubricating properties, it is widely used for lining materials, various gears, packing, lining of ski plates, skating links, and the like. However, ultra-high-molecular-weight polyethylene is said to have poor moldability because it has a significantly higher viscosity than general-purpose polyethylene. In order to improve the molding processability, it is required to have properties such as a small particle size of polyethylene powder, a narrow particle size distribution and a high bulk density. In addition, it is said that the yield of the polymer per catalyst component is high. Normal catalytic performance is also essential.

It is known that in order to obtain such ultrahigh molecular weight polyethylene, it is necessary to select an appropriate solid catalyst component, an organoaluminum compound. In particular, many improvements have been made and proposed for solid catalyst components. The main component is magnesium halide or titanium halide as an essential component, and if necessary, is composed of an electron donating compound such as a silicon compound, but it is particularly commonly used among magnesium halides. Chlorine contained in the existing magnesium chloride adversely affects the produced polymer,
Since problems such as corrosion of the equipment used remain, it is required that the activity be high enough to ignore the effect of chlorine.
Or, there was an unsolved part, such as the need to keep the concentration of magnesium chloride itself low.

Therefore, in JP-A-2-70710, it is disclosed that magnesium chloride is not used as a starting material.
A solid catalyst component has been proposed which comprises an oxygen-containing inorganic compound of magnesium, an aluminum halide ether and a titanium compound as essential components.

According to the publication, it has excellent properties as a solid catalyst component used in the production of ultra high molecular weight polyethylene, but the polymer yield per catalyst component (catalytic activity) is low, and further improvement is required. It was what was desired.

The inventors of the present invention disclosed in Japanese Patent Laid-Open No. 3-24103 that diethoxymagnesium was treated with an aromatic dicarboxylic acid diester and titanium tetrachloride in the presence of an aliphatic dihalogenated hydrocarbon in two steps. We have proposed a solid catalyst component to be obtained and have succeeded in obtaining ultra-high molecular weight polyethylene with an average molecular weight of 2,000,000 or more in a high yield.

[0007]

However, the polyethylene obtained by using the above-mentioned solid catalyst component developed by the present inventors has a small average particle size, and the polymer yield per catalyst component (catalytic activity ) Also showed excellent properties, but it was not sufficient in terms of particle size distribution and bulk density, leaving room for further improvement. The present inventors have left a problem left over in the prior art, namely, a solid that can obtain ultrahigh molecular weight polyethylene with a small particle size, a narrow particle size distribution and a high bulk density in a high yield without using magnesium halide. As a result of extensive studies to develop a catalyst component, the present invention has been completed based on the finding that the target solid catalyst component can be obtained by forming the intermediate composition during preparation of the solid catalyst component into fine particles. Came to do.

[0008]

That is, the present invention is
A homogeneous solution obtained by heat-mixing (a) diethoxymagnesium and (b) tetrabutoxytitanium was added with (c) silicon tetrachloride and (d) an aromatic carboxylic acid diester in the presence of an inert organic solvent. (E) Sorbitan fatty acid ester, which is a fine particulate solid composition produced by reacting in a temperature range of 40 ° C. or higher and the boiling point of the inert organic solvent or lower In the coexistence of (f) titanium tetrachloride, and then (d) aromatic carboxylic acid diester is added,
The present invention provides a solid catalyst component for the production of ultra-high molecular weight polyethylene, which is structurally characterized by being obtained by treatment in a temperature range of ° C.

As the (d) aromatic dicarboxylic acid diester (hereinafter sometimes simply referred to as (d) substance) used in the present invention, phthalic acid diesters are preferable, for example, dimethyl phthalate, diethyl phthalate,
Dipropyl phthalate, dibutyl phthalate, diisobutyl phthalate, diamyl phthalate, diisoamyl phthalate, ethyl butyl phthalate, ethyl isobutyl phthalate, ethyl propyl phthalate, isooctyl phthalate -G.

The sorbitan fatty acid ester (e) used in the present invention (hereinafter sometimes referred to simply as the substance (e)) is sorbitan monolaurate, sorbitan monostearate, sorbitan distearate, Examples thereof include sorbitan monooleate and sorbitan sesquioleate.

In the present invention, a uniform solution of (a) diethoxymagnesium (hereinafter sometimes simply referred to as (a) substance) and (b) tetrabutoxytitanium (hereinafter sometimes simply referred to as (b) substance) is obtained. , (A) substance and (b)
It is formed by mixing and contacting the substance with stirring in the temperature range of 50 to 150 ° C. for 10 minutes or longer, preferably 1 hour or longer. In this case, the ratio of the amount of the substance (a) and the amount of the substance (b) used are arbitrary, but usually 0.5 to 1 g of the substance (a) is used for the substance (b)
It is preferably used in the range of 2.0 g. Further, although the formed uniform solution has a high viscosity, it is desirable to use it after diluting it with an inert organic solvent such as hexane, heptane, toluene, xylene or the like in consideration of the ease of operation.

The homogeneous solution obtained as described above is sometimes referred to as (c) silicon tetrachloride (hereinafter simply referred to as (c) substance) in the presence of an inert organic solvent such as hexane, heptane, toluene and xylene. ) And (d) substances, and then reacting with each other to produce a finely divided solid composition having primary particles of usually 1 micron or less. In this case, the ratio of each substance used is not particularly limited, but usually 0.5 g to 50 ml of the substance (c) and 0.01 ml to 1.0 ml of the substance (d) per 1 g of the substance (a). The inert organic solvent coexisted at this time is optional, but usually 0.5 g per 1 g of the substance (a).
It is in the range of ~ 100 ml.

The contact of the homogeneous solution with the substances (c) and (d) is carried out in the presence of the inert organic solvent at -20
It is carried out by a method in which a uniform solution is gradually dropped into a mixed solution of the substance (c) and the substance (d) in a temperature range of -10 ° C. After the completion of dropwise addition of the homogeneous solution, the temperature is raised and the reaction is carried out in the temperature range of 40 ° C. or higher and the boiling point of the used inert organic solvent or lower, whereby a fine particle solid composition having primary particles of 1 micron or less is produced,
The reaction time is 10 minutes to 100 hours. At this time, when the contact temperature between the homogeneous solution and the substances (c) and (d) is 10 ° C or higher, or the reaction temperature after the contact is 40 ° C or lower,
It is difficult to obtain a finely divided solid composition with high uniformity, and as a result, a solid catalyst component sufficient to achieve the intended purpose cannot be prepared.

The fine particulate solid composition is washed with an inert organic solvent such as heptane, if necessary, and then, in the presence of the substance (e),
After contacting with (f) titanium tetrachloride (hereinafter sometimes referred to simply as "(f) substance"), the (d) substance is added to 40-130.
The solid catalyst component of the present invention is obtained by treating in the temperature range of ° C. The substance (e) can be arbitrarily selected to be used by adding it to the finely divided solid composition or used in advance in the substance (f). The usage ratio of each substance at this time is usually 0.01 to 1.0 ml for the substance (d) for 1 g of the substance (a),
The substance (e) is used in an amount of 0.01 to 0.5 g, and the substance (f) is used in an amount of 0.1 to 10 ml. The substance (f) may be used by diluting it with a hydrocarbon solvent such as hexane, heptane, decane, toluene, xylene or the like in the contact treatment, and repeated contact treatment with the substance (f) is not hindered.

The contact treatment temperature is in the range of 40 to 130 ° C.,
The contact treatment time is appropriately set within the range of 10 minutes to 100 hours. The solid catalyst component prepared as described above can be washed with an inert organic solvent such as heptane, and it can be used as it is after washing or after washing and drying, and then combined with an organoaluminum compound to produce ultrahigh molecular weight polyethylene. Form a polymerization catalyst for manufacturing.

[0016] Is a hydrocarbon group, and X is a halogen atom 1 ≦ n ≦ 3. )
And specifically include triethylaluminum, triisobutylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, and the like. It is also possible to use a mixture of two or more of these organoaluminum compounds.

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. Polymerization temperature is 0-15
The polymerization pressure is 0 to 100 kg / cm ² · G at 0 ° C. Further, upon polymerization, esters, ketones, amines, Si-O
It is also possible to add and use an electron donating compound such as a silicon compound having a -C bond.

[0018]

When ethylene is polymerized using the solid catalyst component of the present invention, the produced polyethylene has an average molecular weight of about 2,000,000 or more, a small average particle size, a high bulk density and a narrow particle size distribution. Moreover, it exhibits excellent catalytic activity, which proves that it acts as a solid catalyst component in the field in an extremely well-balanced manner.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 <Preparation of solid catalyst component> 100 g of diethoxymagnesium and 124 ml of tetrabutoxytitanium were charged into a round-bottomed flask having a capacity of 2 l, which was sufficiently replaced with nitrogen gas and equipped with a stirrer, and the mixture was stirred at 130 ° C for 6 hours. By carrying out the treatment, a homogeneous solution having a high viscosity was obtained. After cooling this to 90 ℃,
Toluene (800 ml) preheated to ℃ was added and stirred for 1 hour to obtain a colorless transparent uniform solution. This homogeneous solution
90 ml was taken, charged into a 500 ml round-bottomed flask equipped with a stirrer prepared separately, 0.5 ml of di-2-ethylhexyl phthalate kept at 0 ° C., 50 ml of silicon tetrachloride and n.
-While maintaining the temperature in the system at 0 ° C, the mixture was added dropwise to a mixed solution of 150 ml of heptane over 1 hour while stirring at 300 rpm. Then, the temperature was raised to 55 ° C. over 1 hour, and the reaction was performed for 1 hour to obtain a white fine particulate solid composition. Then, the stirring was stopped to remove the supernatant in the system, 40 ml of toluene was newly added, and 20 ml of titanium tetrachloride in which 0.5 g of sorbitan distearate was dissolved was added thereto. After that, 1.5 ml of di-n-butyl phthalate was added, and the temperature was raised to 110 ° C over 3 hours, and the temperature in the system was changed to 110 ° C.
The treatment was carried out for 2 hours while maintaining the temperature. Finally, at room temperature
-A solid catalyst component was obtained by washing 7 times with 100 ml of heptane. The titanium content in this solid catalyst component was 2.4% by weight.

<Polymerization> A stainless steel autoclave equipped with a stirrer and having an inner volume of 1500 ml, which is completely replaced with ethylene gas.
Charge 700 ml of n-heptane into the flask and add 0.70 of triethylaluminum while keeping it in an ethylene gas atmosphere at 20 ° C.
Charged mmol. Next, after the temperature was raised to 70 ° C., 0.0052 mmol of the solid catalyst component was charged as titanium atom, and the pressure in the system was adjusted to
Polymerization was carried out for 3 hours while feeding ethylene so that the pressure was 4 kg / cm ² · G. The obtained polymer was separated by filtration and dried under reduced pressure to obtain 313 g of polyethylene powder. The catalyst activity was 30,200 g / g-cat. In terms of polymer yield per 1 g of catalyst component after 3 hours of polymerization. The polymer obtained has a bulk density of 0.42 g / cm ³ and an integrated weight of 5
The average particle size, expressed as 0%, was 160 microns. Spread of particle size distribution (SPAN) is (Dp90-Dp10) / Dp50
(Here, Dpx represents a particle size at an integrated weight of X%.)
, SPAN = 0.5. The average molecular weight of this polymer determined from the intrinsic viscosity in decalin (135 ° C) was 3.5 million.

Example 2 Di-2-2 used in forming a mixed solution with silicon tetrachloride
An experiment was conducted in the same manner as in Example 1 except that di-n-butyl phthalate was used instead of ethylhexyl phthalate. The results obtained are shown in the table. It is as shown in 1.

Example 3 An experiment was conducted in the same manner as in Example 1 except that 0.5 g of sorbitan distearate was replaced with 0.3 g of sorbitan sesquioleate. The results obtained are shown in the table. It is as shown in 1.

[0023]

When ethylene is polymerized using the solid catalyst component obtained by the present invention, the average molecular weight is 20%.
Ultra high molecular weight polyethylene of more than 0,000 can be obtained in high yield. In addition to that, a characteristic effect of the present invention is that the average particle size is as small as 100 to 200 microns, the particle size distribution is narrow, and a highly active solid catalyst capable of obtaining a high bulk density ultra high molecular weight polyethylene. To provide the ingredients. In addition, since the particle size distribution is not significantly affected by changes in stirring conditions during catalyst preparation,
It also has advantages such as easy scale-up and less loss of the raw material magnesium compound, so that the solid catalyst component can be produced at a relatively low cost.

[Brief description of drawings]

FIG. 1 is a flowchart showing the steps for preparing a solid catalyst component according to the present invention.

[Table 1] Table. 1 Note 1) Note 2) Example No. Ti content Catalytic activity Bulk density Average particle size SPAN Average molecular weight (wt%) (g-PE / g-cat.) (G / ml) (micron) 2 2.9 31,000 0.39 150 0.4 2.8 million 3 2.8 33,400 0.40 140 0.5 3 million Note 1) SPAN = (Dp90-Dp10) / Dp50 Note 2) Calculated value from the intrinsic viscosity in decalin (135 ° C)

Claims (1)

[Claims] 1. A homogeneous solution obtained by heating and mixing (a) diethoxymagnesium and (b) tetrabutoxytitanium in the presence of an inert organic solvent, (c) silicon tetrachloride and (d) aromatic Contact with the carboxylic acid diester in the temperature range of -20 to 10 ° C and then raise the temperature to 40
A fine particulate solid composition produced by reacting at a temperature of not less than ℃ and not more than the boiling point of the inert organic solvent is contacted with (f) titanium tetrachloride in the presence of (e) sorbitan fatty acid ester, and then (d) aroma A solid catalyst component for producing ultra-high molecular weight polyethylene, which is obtained by adding a dicarboxylic acid carboxylic acid diester and treating it in a temperature range of 40 to 130 ° C.