JPH0713105B2 - 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 producing a highly crystalline polypropylene by a specific polymerization method.

Conventional technology Polypropylene is a polymer with excellent rigidity, but its impact resistance, especially at low temperatures, is inferior, so impact resistance can be improved by block copolymerization with other olefins such as ethylene. (For example, Japanese Patent Publication No. 44-20621,
Japanese Examined Japanese Patent Publication Sho 49-24593, Japanese Examined Patent Publication Sho 49-12589, etc. ) However, when block copolymerization is inevitably carried out, the rigidity becomes poor in proportion to the improvement in impact resistance. Therefore, improving the rigidity of polypropylene itself does not only improve the physical properties of polypropylene but also propylene. It is also extremely important in terms of improving the physical properties of the block copolymer.

Problems to be solved by the invention Since the rigidity of a crystalline polymer such as polypropylene correlates with the degree of crystallization of the polymer, adding a nucleating agent improves the crystallization temperature and crystallinity of the polymer to improve the rigidity of the polymer. Although it is often improved, if a relatively large amount of nucleating agent is not added, it is not effective, and if a large amount of nucleating agent is added, unevenness in the partial physical property balance of the molded product due to uneven distribution of the nucleating agent. As a result, there is a problem that the physical properties of the molded product become poor, or the nucleating agent bleeds and the appearance of the molded product becomes poor.

Means for Solving the Problems The present inventors have conducted extensive studies on a method for solving the above problems and completed the present invention. That is, the present invention relates to a method of polymerizing propylene using a catalyst comprising a transition metal catalyst component containing trivalent and / or tetravalent titanium halide and an organoaluminum compound, and previously converting the catalyst to 4,4-dimethylhexene-1. A method for producing a highly crystalline polypropylene, which comprises polymerizing propylene after the contact treatment.

In the present invention, the catalyst comprising the transition metal catalyst component and the organoaluminum compound is not particularly limited, and various known catalyst systems which give polypropylene having high stereoregularity can be used. Titanium halide is preferably used as the transition metal catalyst component. For example, titanium trichloride obtained by reducing titanium tetrachloride with metallic aluminum, hydrogen or organic aluminum, or those modified with an electron donating compound and an organic aluminum compound. Further, if necessary, a catalyst system comprising a stereoregularity improving agent such as an oxygen-containing organic compound, or a carrier such as magnesium halide or those obtained by treating them with an electron-donating compound and supporting titanium halide thereon. An example is a catalyst system comprising an organoaluminum compound and, if necessary, a stereoregularity improver such as an oxygen-containing compound. (For example, various examples are described in the following literature. Ziegler Natta Catalysts and Poly
merization by John Boor Jr (Academic Press), Journ
al of Macromolecular Science-Reviews in Macromole
cular Chemistry and Physics C24 (3) 355-385 (19
84) C25 (1) 57-97 (1985)). Here, oxygen-containing compounds such as ethers, esters, orthoesters, and alkoxysilicons can be preferably used as the stereoregularity improver or electron donor, and alcohols, aldehydes, water and the like can also be used as electron donors.

As the organoaluminum compound, tolualkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, and alkylaluminum dihalide can be used, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Examples of halides include chlorine, bromine and iodine.

Preferred titanium halides are aluminum, or titanium trichloride obtained by reducing titanium tetrachloride with organoaluminum, modified with ether or ester, or magnesium chloride and an organic compound co-ground. Those treated with titanium tetrachloride or the reaction product of magnesium chloride and alcohol are dissolved in a hydrocarbon solvent and then treated with a precipitating agent such as titanium tetrachloride to make them insoluble in the hydrocarbon solvent, and if necessary, ester, ether It is a halogen compound of supported titanium obtained by a method such as a modification treatment with an electron donating compound such as the above, followed by a treatment with titanium tetrachloride.

What is important in the present invention is to pre-contact the catalyst with 4,4-dimethylhexene-1. In this case, the use ratio of the organoaluminum compound / transition metal catalyst component may be the same as or less than that in the subsequent polymerization of propylene, and the amount ratio is 0.5 to 1000. Is common. Further, in that case, a stereoregularity improver can be present, and its preferable ratio is 0.
01 to 300.

The contact treatment temperature and the contact treatment time are not particularly limited, but generally, the temperature is the same as or lower than the temperature during the subsequent propylene polymerization, and the contact treatment time is several minutes to
It is generally several hours, preferably, the treatment is carried out under the condition that 4,4-dimethylhexene-1 is reacted in the amount of 0.001 equivalent to 200 equivalent times per transition metal catalyst component. This catalytic treatment is carried out in an inert medium such as butane, pentane, hexane, heptane, octane, nonane, decane, toluene, xylene, ethylbenzene or a mixture thereof for the Ziegler-Natta catalyst and, if necessary, unreacted 4,4. It is also possible to remove dimethylhexene-1 and wash it, and then add an organoaluminum compound and use it for the polymerization of propylene.

If the reaction amount of 4,4-dimethylhexene-1 is 0.001 equivalent or less per transition metal catalyst component, there is almost no effect, and if it is 200 equivalent times or more, problems such as poor surface when molded polypropylene obtained are preferable. Absent.

In the present invention, the polymerization of propylene can be carried out in the above-mentioned inert medium, or can be carried out by a bulk polymerization method using propylene itself as a liquid medium, or a gas phase polymerization method in which substantially no liquid medium exists, The polymerization temperature is usually from room temperature to 100 ° C. The polymerization pressure is usually from atmospheric pressure to 50 kg / cm ² · gauge.

The present invention also includes not only propylene homopolymerization but also copolymerization with other α-olefins such as ethylene in a small amount of up to several% or ethylene in the latter stage or copolymerization with other α-olefins in the latter stage or ethylene in the latter stage. Or other α-
It can also be applied to the production of so-called block copolymers in which copolymerization is performed such that the olefin accounts for 20 to 95 wt% of the polymer in the part.

Effects By carrying out the method of the present invention, a highly crystalline polypropylene can be easily produced, which is extremely industrially significant.

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

Example 1 A vibration mill equipped with four grinding pots having an inner volume of 4 and containing 9 kg of steel balls having a diameter of 12 mm is prepared. 300 g of magnesium chloride and tetraethoxysilane in a nitrogen atmosphere in each pot.
60 ml and α-α-α-trichlorotoluene 45 ml were added and pulverized for 40 hours.

300 g of the above co-ground product was placed in a flask of 5 and titanium tetrachloride was added.
1.5 and toluene 1.5 were added and the mixture was stirred at 100 ° C. for 30 minutes. Then, leave it standing and remove the supernatant liquid in the same manner as in titanium tetrachloride 1.5.
Toluene 1.5 was added, the mixture was stirred at 100 ° C. for 30 minutes, the supernatant was removed, and the solid content was washed with n-heptane of 4 again 10 times. One part of the obtained solid catalyst slurry was sampled. Analysis of titanium content
It was 1.9% by weight.

ii) Polymerization reaction In a flask with an internal volume of 200 ml, under a nitrogen atmosphere, toluene 40 ml, the above solid catalyst 20 mg, diethylaluminum chloride 0.12
Add 8 ml, methyl p-toluate 0.06 ml, triethylaluminum 0.03 ml, and 1,4-dimethylhexene-1 1 ml.
After stirring treatment at 40 ° C for 30 minutes, triethylaluminum 0.
Added 05 ml. This catalyst slurry was put into an autoclave with an internal volume of 5 and 1.8 kg of propylene and 3.3 Nl of hydrogen were added.
The polymerization reaction was carried out at 0 ° C for 2 hours. After the polymerization reaction, the unreacted propylene was purged and the polymer was taken out at 80 ° C and 60 mmHg.
Dried for hours. 480 g of powder was obtained and the intrinsic viscosity (hereinafter abbreviated as η) measured with a tetralin solution at 135 ° C. and the ratio of extraction residual ratio when extracted with a Soxhlet extractor for 6 hours in boiling n-heptane (abbreviated as II below) Then, a phenolic stabilizer was added at a weight ratio of 10/10000 and calcium stearate was added at a weight ratio of 15/10000, and the mixture was granulated, the melt flow index was measured, and an injection sheet having a thickness of 1 mm was prepared to measure the flexural rigidity.

Melt flow index ASTM D1238 (230 ° C) Flexural rigidity ASTM D747-63 (20 ° C) (): Measurement temperature.

The results obtained by measuring the melting point and the crystallization temperature as the maximum peak temperatures by raising or lowering the temperature at 10 ° C / min using a differential thermal analyzer are shown in the table. A model experiment was carried out without polymerizing propylene, and the amount of 1,4-dimethylhexene-1 polymerized with respect to the transition metal catalyst component was measured.

Comparative Example 1 The same as Example 1 except that the contact treatment with 4,4-dimethylhexene-1 was not carried out. 475 g of polypropylene was obtained.

Example 2 The same as Example 1 except that the contact treatment with 4,4-dimethylhexene-1 was carried out in the presence of 0.08 ml of triethylaluminum. 1.9 equivalents of 4,4-dimethylhexene-1 were polymerized per transition metal catalyst component, and the amount of polypropylene obtained was 470 g. The results are shown in the table.

Example 3 Commercially available highly active titanium trichloride was used as a transition metal catalyst component (TAC-S-21 manufactured by Toho Titanium Co., Ltd.). Highly active titanium trichloride 100 mg diethylaluminum chloride 1.0 ml, 4,4-dimethylhexene-1 in 50 ml toluene.
0.8g was contact-treated at 40 ° C for 1 hour. Then put this slurry in an autoclave with an internal volume of 5 and propylene 1.8K
g and 4.4 Nl of hydrogen were added and a polymerization reaction was carried out at 75 ° C. for 4 hours to obtain 940 g of propylene. This polypropylene was autoclaved in the presence of propylene oxide at 100 ° C for 1 hour.
After the time treatment, granulation was performed in the same manner as in Example 1 and the physical properties were measured. The results are shown in the table. The polymerization amount of 4,4-dimethylhexene-1 was 0.4 equivalent per titanium trichloride catalyst component.

Comparative Example 2 Same as Example 3 except that 4,4-dimethylhexene-1 was not used. The results are shown in the table.

Comparative Example 3 The procedure of Example 1 was repeated except that the amount of 4,4-dimethylhexene-1 used was 0.5 mg. The results are shown in the table. At this time, the polymerization amount of 4,4-dimethylhexene-1 per titanium trichloride catalyst component was less than 0.001, and the results are shown in the table.

[Brief description of drawings]

FIG. 1 is a flow chart of the Ziegler catalyst according to the present invention.

Claims (2)

[Claims] 1. A method for polymerizing propylene using a catalyst comprising a transition metal catalyst component containing trivalent and / or tetravalent titanium halide and an organoaluminum compound, wherein the catalyst is previously 4,4-dimethylhexene-1. A method for producing a highly crystalline polypropylene, which comprises polymerizing propylene after contacting with propylene. 2. A patent for the catalytic treatment under the condition that 4,4-dimethylhexene-1 is reacted 0.001 equivalent times or more and 200 equivalent times or less per transition metal catalyst component containing trivalent and / or tetravalent titanium halide. The method according to claim 1.