JPH0713104B2 - 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 poor, so impact resistance can be improved by block copolymerization with other olefins such as ethylene. However, for example, when block copolymerization is performed, impact resistance is inevitably improved and rigidity becomes poor correspondingly. Therefore, improving the rigidity of polypropylene itself is extremely important not only for improving the physical properties of polypropylene but also for improving the physical properties of propylene block copolymer.

Problems to be Solved by the Invention Since the rigidity of crystalline polymers 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. It is often improved, but it is not effective unless a relatively large amount of nucleating agent is added, and when a large amount of nucleating agent is added, the physical property balance of the molded product becomes poor due to uneven dispersion of the nucleating agent, There is a problem that the 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-mentioned problems and completed the present invention. That is, in the present invention, in the method of polymerizing propylene using a catalyst comprising a transition metal catalyst component containing trivalent and / or tetravalent titanium halide and an organoaluminum compound, the catalyst is previously changed to 4,4-dimethylpentene-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 halides are preferably used as the transition metal catalyst component. For example, titanium tetrachloride obtained by reducing titanium tetrachloride with metallic aluminum, hydrogen or organic aluminum, or those modified with an electron donating compound and organic Aluminum compound and, if necessary, a catalyst system comprising a stereoregularity improving agent such as an oxygen-containing organic compound, a carrier such as magnesium halide, or a product obtained by treating them with an electron-donating compound and carrying titanium halide. Illustrative is a catalyst system comprising an organoaluminum compound and optionally a stereoregularity improver such as an oxygen-containing compound. (For example, various examples are described in the following documents.

Ziegler Natta catalysts and Polymerization by John
Boon Jr (Academic Press), Journal of Macromolecul
ar Science-Reviews in Macromoleculer Chemistry an
d Physics C24 (3) 355-385 (1984) 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 those obtained by reducing titanium tetrachloride obtained by reducing titanium tetrachloride with aluminum or organoaluminum, modified with ether or ester, or those obtained by co-grinding magnesium chloride and an organic compound. What was treated with titanium tetrachloride or the reaction product of magnesium chloride and alcohol was dissolved in a hydrocarbon solvent and then treated with a precipitating agent such as titanium tetrachloride to make it insoluble in the hydrocarbon solvent, and if necessary, ester, ether, etc. Is a halogen compound of supported titanium obtained by a method such as a modification treatment with an electron-donating compound, and then treatment with titanium tetrachloride.

What is important in the present invention is to pre-treat the catalyst with 4,4-dimethylpentene-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. At that time, a stereoregularity improver can be present, and its preferable ratio is 0.01
~ 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 in the subsequent propylene polymerization, and the contact treatment time is several minutes to several hours. Is generally used, and preferably, the treatment is carried out under the condition that at least 0.001 equivalent of 4,4-dimethylpentene-1 reacts with the transition metal catalyst component. This catalytic treatment is carried out in an inert medium for the Ziegler-Natta catalyst such as pentane, hexane, heptane, octane, nonane, decane, benzene, toluene, xylene, ethylbenzene, or a mixture thereof, and optionally unreacted 4,4 It is also possible to remove dimethylpentane-1 and wash it, and then add an organoaluminum compound and use it for the polymerization of propylene.

The amount of 4,4-dimethylpentene-1 used is preferably 0.01 equivalent times or more per transition metal catalyst component. If it is less than 0.01 equivalent, there is almost no effect. In addition, when treated under the condition of reacting 200 equivalents or more, it is not preferable because the polypropylene obtained has problems such as a defective surface.

In the present invention, the polymerization of propylene may be carried out in the above-mentioned inert medium, or by a bulk polymerization method using propylene itself as a liquid medium, or a gas phase polymerization method in the absence of a substantially liquid inert medium. The polymerization temperature can be room temperature to 10
The polymerization pressure at 0 ° C. is normal 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 up to a few%, or in the latter stage, ethylene or, if necessary, other α-olefins is added to the polymer in the polymer. It can also be applied to the production of so-called block copolymers in which copolymerization is performed so as to account for 20 to 95 wt% of the coalescence.

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 magnesium chloride and tetraethoxysilane in a nitrogen atmosphere in each pot
60 ml and 45 ml of α, α, α-trichlorotoluene were added and crushed 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 Toluene 1.5 was added and stirred at 100 ° C. for 30 minutes. Then, after allowing to stand, the supernatant liquid is removed and similarly titanium tetrachloride 1.5 and toluene 1.5 are added, and the mixture is stirred at 100 ° C. for 30 minutes. Then, the supernatant liquid is removed, and the solid content is further washed with n-heptane of 4. When a part of the solid catalyst slurry obtained by repeating 10 times was sampled and the titanium content was analyzed, 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
8ml Methyl p-toluate 0.06ml, triethylaluminum 0.03ml, 4,4-dimethylpentene-1 0.2g were added and stirred at 40 ° C for 30 minutes, then triethylaluminum.
0.05 ml was added. This catalyst slurry is put into an autoclave with an internal volume of 5 and 1.8 Kg of prolene and 3.3 Nl of hydrogen are added and the temperature is 75 ° C
The polymerization reaction was carried out for 2 hours. After the polymerization reaction, propylene in the end reaction was purged and the polymer taken out was dried at 80 ° C. and 60 mmHg for 12 hours. 470 g of powder was obtained, the intrinsic viscosity (hereinafter abbreviated as η) measured with a tetralin solution at 135 ° C., and the ratio of the extraction residual ratio when extracted with a Soxhlet extractor for 6 hours in boiling n-heptane (hereinafter II and Abbreviated), 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 a bending rigidity was measured by making an injection sheet with a thickness of 1 mm. .

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 crystallization temperature as the maximum peak temperature 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 polymerization amount of 4,4-dimethylpentene-1 with respect to the transition metal catalyst component was measured and found to be 1.3 equivalents relative to the transition metal catalyst component.

Comparative Example 1 The same as Example 1 except that the contact treatment with 4,4-dimethylpentene-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-dimethylpentene-1 was carried out in the presence of 0.08 ml of triethylaluminum. 1.8 equivalents of 4,4-dimethylpentene-1 were polymerized per a pair of transition metal catalyst components, 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.). 100 mg of the above highly active titanium trichloride in 50 ml of toluene 1.0 ml of diethylaluminum chloride, 4,4-dimethylpentene-
10.3 g was contact-treated at 40 ° C. for 1 hour. This slurry was then placed in an autoclave with an internal volume of 5 and propylene 1.
When 8 kg of 4.4 Nl of hydrogen was added and the polymerization reaction was carried out at 75 ° C for 4 hours, 960 g of propylene was obtained. 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. Also, the polymerization amount of 4,4-dimethylpentene-1 per 0.4 parts of titanium trichloride catalyst component was 0.4 equivalent.

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

Comparative Example 3 The same results as in Example 1 except that the amount of 4,4-dimethylpentene-1 used was 0.5 mg are shown in the table. At this time, the polymerization amount of 4,4-dimethylpentene-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 showing the catalytic treatment of a transition metal catalyst and an organoaluminum compound with 4,4-dimethylpentene-1.

Claims (3)

[Claims] 1. In 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, the catalyst is previously 4,4-dimethylpentene-1. A method for producing a highly crystalline polypropylene, which comprises polymerizing propylene after contacting with propylene. 2. The use of 0.01-fold or more of 4,4-dimethylpentene-1 with respect to the transition metal catalyst component containing trivalent and / or tetravalent titanium halide.
Method described in section. 3. A patent for carrying out a contact treatment under the condition of reacting 4,4-dimethylpentene-1 with 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.