JPH0794489B2 - Polymerization method of propylene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for polymerizing propylene. Specifically, it relates to a method for polymerizing propylene by controlling the stereoregularity of the obtained polypropylene.

[Conventional technology]

It is well known about the method of polymerizing propylene using a catalyst composed of titanium trichloride and an organoaluminum compound, and in order to obtain polypropylene with high activity and high stereoregularity, titanium trichloride can be used in various electron donating properties. It is also well known to modify with a compound (see, for example, JP-A-4747).
-34478).

[Problems to be solved by the invention]

It is generally preferable to provide polypropylene with high activity and high stereoregularity, but in order to actually use polypropylene as a molding material, the stereoregularity of polypropylene must be a constant value. If the stereoregularity of is too high, there is a problem that it is fragile and cannot be put to practical use. Therefore, a propylene polymerization method in which the stereoregularity of the obtained polypropylene is controlled within a certain range is desired.

On the other hand, the combined use of trialkylaluminum and dialkylaluminum chloride can improve the activity of the titanium catalyst (for example, JP-B-37-11538), and trialkylaluminum and dialkylaluminum chloride can be prepared by bulk polymerization using propylene itself as a medium. When used together,
It is known that the physical properties of the obtained polymer can be improved (for example, JP-B-47-31702), but it is extremely difficult to bring the stereoregularity of the obtained polymer into a desired range,
When a component soluble in the polymerization medium is to be removed from the resulting polymer for the purpose of removing a propylene oligomer or a catalyst residue, there is a problem that the stereoregularity of the obtained propylene polymer cannot be controlled.

[Means for solving problems]

The present inventors conducted extensive studies on a method for solving the above problems, found that the above problems could be solved by adopting a specific method, and completed the present invention.

That is, the present invention is a method for polymerizing propylene using a catalyst comprising a titanium trichloride catalyst and an organoaluminum compound, wherein titanium trichloride modified with ether is used as the titanium trichloride catalyst, and dialkylaluminum chloride and triethyl are used as the organoaluminum compound. Using aluminum together, polymerizing propylene in the presence of a liquid medium,
Then, the propylene polymer dissolved in the liquid medium is removed, and the stereoregularity of polypropylene obtained by controlling the ratio of dialkylaluminum chloride and triethylaluminum in the range of 1 / 0.02 to 1 / 0.15 during polymerization is controlled. Is a method for producing a stereoregular polymer.

Various ether-modified titanium trichloride catalysts used in the present invention are already known, and they can be obtained on the market as olefin polymerization catalysts.
For example, a method of co-grinding with ether or further extraction with an inert hydrocarbon (Japanese Patent Publication Nos. 43-10065 and 42-3024).
Issue, Japanese Examined Sho 43-15620, Examined Sho 49-2021, Examined Sho 49-23
No. 591, Japanese Patent Publication No. 49-7074, Japanese Patent Publication No. 49-17873, etc.), a method of reducing titanium tetrachloride with organoaluminum in the presence or absence of ether, and further subjecting it to catalytic treatment with ether if necessary (JP JP-A-48-64170, JP-A-47-34478, JP-A-55-40757, JP-A-55-40758) and the like.

Specific examples of ethers include diethyl ether, dibutyl ether, diphenyl ether and the like.

Examples of the dialkyl aluminum chloride in the present invention include diethyl aluminum chloride, dimethyl aluminum chloride, dipropyl aluminum chloride, dibutyl aluminum chloride, dihexyl aluminum chloride and the like, diethyl aluminum chloride, dipropyl aluminum chloride,
Dibutyl aluminum chloride is preferably used. The use ratio of dialkylaluminum chloride to titanium trichloride catalyst is 1.0 mol times or more, preferably about 1.5 mol times to 30 mol times, and the ratio of dialkylaluminum chloride and triethylaluminum is 1 / 0.02 to 1 / 0.15. When it is 0.02 or less, the stereoregularity of the obtained polypropylene is undesirably not when triethylaluminum is not used, and when it is more than 0.15, the polymer of propylene dissolved in the liquid medium used for the polymerization is significantly increased, which is not preferable.

What is important in the present invention is to polymerize propylene in the presence of a liquid medium using the above catalyst and remove the polymer dissolved in the liquid medium after the polymerization reaction to obtain a stereoregular polymer of propylene. . Examples of liquid medium and liquid propylene itself include butane, pentane, hexane, heptane, nonane, decane, benzene, toluene, xylene, ethylbenzene, and mixtures thereof. Various methods can be adopted to separate the stereoregular polymer of propylene and the polymer dissolved in these media, and filtration, centrifugation, countercurrent washing and the like are common.

Polymerization of propylene is usually room temperature to 100 ° C, preferably 40 ° C to 8 ° C.
The polymerization is carried out at 0 ° C., and the polymerization pressure is generally atmospheric pressure to 50 kg / cm ² gauge.

Further, the separation from the polymer dissolved in the liquid medium is preferably carried out at the temperature used for the above-mentioned polymerization or at a lower temperature.

The method of the present invention can be preferably applied particularly when producing a propylene homopolymer, and can give a polymer having a desired stereoregularity in a high yield.

〔Example〕

 The present invention will be further described below with reference to examples.

Example 1 30 g of titanium trichloride (TAC-140 manufactured by Toho Titanium Co., Ltd.) obtained by reducing titanium tetrachloride with aluminum and 1 ml of titanium tetrachloride were co-ground for 10 hours, and then 2 ml of diethyl ether and 6 ml of ethyl benzoate were added. In addition, the mixture was further pulverized for 40 hours. The operation of extracting the co-ground product with toluene (100 ml per 10 g of the co-ground product) at 80 ° C. for 30 minutes was repeated 3 times to obtain a titanium trichloride catalyst.

Polymerization was carried out using 300 mg of the above titanium trichloride in an autoclave with an internal volume of 3 l using n-heptane as a liquid medium. At this time, the use ratio of organoaluminum (triethylaluminum + diethylaluminum chloride) to titanium trichloride was kept constant at 3 mol times, and polymerization was carried out while changing the ratio of triethylaluminum and diethylaluminum chloride. Polymerization was carried out by first charging 400 Nl of hydrogen at 70 ° C at once, and continuing the polymerization reaction for 5 hours while adding propylene so that the total polymerization pressure became 5 kg / cm ² -gauge, then adding 100 ml of isopropyl alcohol to lose the catalyst. After activating, it was filtered at 50 ° C. to obtain polypropylene powder. On the other hand, the solvent was removed from the filtrate by evaporation to obtain a polymer dissolved in a liquid medium. The polypropylene powder was extracted with boiling n-heptane for 6 hours using a Soxhlet extractor, and the boiling n-heptane extraction residual rate, which is a measure of stereoregularity. In addition, the limit number in a 135 ° C. tetralin solution was measured.

Fig. 2 shows the relationship between the ratio of triethylaluminum and diethylaluminum chloride and the boiling n-heptane extraction residual ratio of the resulting polypropylene powder and the yield of polypropylene powder ((polypropylene powder / (polypropylene powder + soluble polymer) x 100 as (Calculation) and the intrinsic viscosity number and the activity of producing polypropylene powder per titanium trichloride catalyst, it is understood that the yield of polypropylene powder is significantly reduced when the ratio of triethylaluminum to diethylaluminum chloride exceeds 0.15.

Comparative Example 1 The same as Example 1 except that the titanium trichloride catalyst (TAC-140) obtained by reducing titanium tetrachloride with aluminum was used as it was. As shown in FIG. 3, the use of triethylaluminum reduces the yield of polypropylene powder.

Example 2 i) Synthesis of titanium trichloride catalyst 600 ml of n-hexane and 150 ml of titanium tetrachloride in 173 ml with stirring.
Diethylaluminum chloride (1) was diluted with 450 ml of n-hexane and added over 4 hours while maintaining the temperature at 0 ° C. Then, the mixed solution was removed to 70 ° C. for 1 hour, the mixture was further stirred at 70 ° C. for 1 hour, and the mixture was allowed to stand and separated, and the supernatant was removed to wash the solid content with n-hexane. Then, the solid content was dispersed in 1720 ml of n-hexane, 256 ml of diisoamyl ether was added, and the mixture was stirred at 30 ° C. for 1 hour and then separated by leaving to stand to remove the supernatant. After stirring for 2 hours, the mixture was allowed to stand, separated, and the supernatant was removed to wash the solid content with n-hexane. By doing so, a titanium trichloride catalyst was obtained. (According to JP-A-47-34478) Using 100 ml of the above catalyst, an autoclave having an internal volume of 5 l was used to polymerize propylene by a bulk polymerization method using propylene itself as a medium. However, 2.7Nl of hydrogen was initially charged at the same time, and the temperature was 3 at 70 ℃.
After polymerization for 100 hours, 100 ml of isopropyl alcohol was added, and after deactivation, unreacted propylene was taken out through a filter, 1 kg of propylene was further added, and after stirring, the same was taken out. The soluble polymer was separated from the extracted propylene. FIG. 4 shows the results when the ratio of triethylaluminum and diethylaluminum chloride was changed by using 10 mol times triethylaluminum and diethylaluminum chloride per titanium trichloride catalyst.

〔The invention's effect〕

As shown in Example 1, the stereoregularity of the polypropylene obtained by carrying out the method of the present invention can be controlled without changing the yield of polypropylene powder, which is extremely valuable industrially.

[Brief description of drawings]

FIG. 1 is a flow chart diagram to aid in understanding the method of the present invention. 2 and 4 are graphs showing the relationship between the ratio of triethylaluminum to diethylaluminum chloride and the stereoregularity of the obtained polypropylene powder when the method of the present invention is carried out, and FIG. Shows the case.

Claims (1)

[Claims] 1. A method for polymerizing propylene using a catalyst comprising a titanium trichloride catalyst and an organic aluminum compound, wherein titanium trichloride modified with ether is used as the titanium trichloride catalyst, and dialkylaluminum chloride and triethyl are used as the organic aluminum compound. Using together with aluminum, polymerizing propylene in the presence of a liquid medium, then removing the polymer of propylene dissolved in the liquid medium,
Moreover, a method for producing a stereoregular polymer of propylene which controls the stereoregularity of polypropylene obtained by changing the ratio of dialkylaluminum chloride and triethylaluminum in the range of 1 / 0.02 to 1 / 0.15 upon polymerization.