JPH0713107B2 - 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 highly crystalline propylene by a specific polymerization method.

[Conventional technology]

Polypropylene is a polymer with excellent rigidity, but since it has poor impact resistance, especially at low temperatures, it is possible to improve impact resistance by block copolymerization with other olefins such as ethylene. (For example, Japanese Patent Publication No.
1, JP-B-49-24593, JP-B-49-12589, etc.). However, block copolymerization improves impact resistance but decreases rigidity. Therefore, in order to improve the physical properties of polypropylene, it is extremely important to improve the physical properties of the 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, there is a method of improving the crystallinity of the polymer by adding a nucleating agent and improving the rigidity of the polymer. There is no effect unless a large amount of nucleating agent is added. Further, when a large amount of nucleating agent is added, uneven dispersion of the nucleating agent occurs, and when formed into a molded product, there is a problem that the physical properties vary or the nucleating agent bleeds and the appearance of the molded product becomes poor.

[Means for solving problems]

The present inventors have earnestly studied a method for solving the above problems and completed the present invention. That is, the present invention relates to 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, and pretreating the catalyst with trialkylvinylsilane or trialkylallylsilane. Then, the propylene is polymerized to produce a highly crystalline polypropylene.

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 organic aluminum. Compound Further, if necessary, a catalyst system comprising a stereoregularity improving agent such as an oxygen-containing organic compound, a carrier such as magnesium halide, or those treated with an electron-donating compound are those obtained by supporting titanium halide. And a catalyst system comprising an organoaluminum and a stereoregularity improver such as an oxygen-containing organic compound as required. (For example, various examples are described in the following literature. Ziegler-Natta Catalysts and Polym
erization by John Boor Jr (Academic Press), Journal
l of Mac-romolecular Science-Reviews in Maclomol
ecular Chemistry and Physics C24 (3) 355-385 (19
84) Same C25 (1) 57-97 (1985)) Here, oxygen-containing compounds such as ethers, esters, orthoesters and alkoxysilicon compounds can be preferably used as the stereoregularity improver or electron donating compound. As the donor compound, alcohol, aldehyde, water or the like can be further used.

As the organic aluminum compound, trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, 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 modifying titanium trichloride obtained by reducing titanium tetrachloride with aluminum or organoaluminum, by modifying it with ether or ester, or by co-milling magnesium chloride and organic compounds. Treated with titanium tetrachloride, or the reaction product of magnesium chloride and alcohol is dissolved in a hydrocarbon solvent and then treated with a precipitating agent such as titanium tetrachloride to make it insoluble in the hydrocarbon solvent. , A supported titanium halide obtained by a method of modifying with an electron-donating compound such as ether and then treating with titanium tetrachloride.

What is important in the present invention is that the catalyst is previously subjected to contact treatment with trialkylvinylsilane or trialkylallylsilane. In this case, the use ratio of the organoaluminum compound / transition metal catalyst component may be the same as that in the subsequent polymerization of propylene, or may be less than that, and the amount ratio is 0.5-1000. Is common. At that time, a stereoregularity improver may be present, and the preferable ratio thereof is 0.01-300. The contact treatment temperature and the contact treatment time are not particularly limited, but are generally the same as or lower than the temperature in the subsequent polymerization of propylene, preferably trialkylvinylsilane or trialkylallylsilane per transition metal catalyst component. Is 0.001 equivalent or more. The contact treatment is pentane, hexane, heptane,
It is carried out in an inert medium for a Ziegler-Natta catalyst such as octane, nonane, decane, benzene, toluene, xylene, ethylbenzene, or a mixture thereof, and if necessary, unreacted trialkylvinylsilane or trialkylallylsilane is removed and washed. It is also possible to add an organoaluminum compound and use it for the polymerization of propylene. The amount of trialkylvinylsilane or trialkylallylsilane 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. Further, when treated under the condition of reacting 200 equivalent times or more, the polypropylene obtained is not preferable because it has a problem that the surface is defective.

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. Normal temperature to 100
The polymerization is carried out at a pressure of -50 ° C and a pressure of 50 to 50 kg / cm ² gauge.

The present invention also relates to propylene homopolymerization as well as copolymerization with other alpha olefins such as ethylene in a small amount of up to several percent, or ethylene or other alpha olefins in the core of a polymer in the latter stage. It can also be applied to the production of so-called block copolymers in which copolymerization occupies ~ 95 W%.

In the present invention, the alkyl of trialkylvinylsilane and trialkylallylsilane is not particularly limited and various alkyl groups such as methyl group, ethyl group, propyl group, butyl group and pentyl group can be exemplified, and the three alkyl groups are the same. But it can be different.

〔Example〕

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

Example 1 A vibration mill equipped with four grinding pots with an inner volume of 4 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 co-ground product was placed in a flask No. 5, titanium tetrachloride (1.5) and toluene (1.5) were added, and the mixture was stirred at 100 ° C. for 30 minutes. Then, the supernatant is removed, titanium tetrachloride 1.5 and toluene 1.5 are added in the same manner, the mixture is stirred at 100 ° C. for 30 minutes, the supernatant is removed, and the solid content is further washed with n-heptane of 4 times, which is repeated 10 times. When a part of the obtained slurry of the solid catalyst was sampled and the titanium content was analyzed, it was 1.9 wt%.

40 ml of toluene under a nitrogen atmosphere in a flask with an internal volume of 200 ml,
20 mg of the above solid catalyst, diethylaluminum chloride.
128 ml, methyl P-toluate 0.06 ml, triethylaluminum 0.03 ml, trimethylvinylsilane 0.4 ml were added 4
After stirring for 30 minutes at 0 ° C, triethylaluminum 0.0
Added 5 ml. Put this catalyst slurry in an autoclave with an internal volume of 5 and add 1.8 kg of propylene and 3.3 NL of hydrogen.
The polymerization reaction was carried out at 0 ° C for 2 hours. After the polymerization reaction, unreacted propylene was purged and the polymer was taken out at 80 ° C and 60 mmHg.
It was dried for 12 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 the extraction residual ratio when extracted with a Soxhlet extractor for 6 hours in boiling n-heptane (hereinafter II and (Abbreviated), then add a phenolic stabilizer at a 10/1000 weight ratio and calcium stearate at a 15/1000 weight ratio, granulate, and measure the melt flow index to make an injection sheet with a thickness of 1 mm, and bend rigidity Was measured.

Melt flow index [MI] ASTM D1238 (230 ° C) Flexural rigidity ASTM D747-63 (20 ° C) The values in () are the measurement temperature and the melting point and temperature can be increased or decreased at 10 ° C / min using a differential thermal analyzer. The results obtained by measuring the crystallization temperature as the maximum peak temperature are shown in Table 1. A model experiment was conducted without polymerizing propylene, and the amount of trimethylvinylsilane polymerized with respect to the transition metal catalyst component was measured and found to be 1.3 equivalents per transition metal catalyst component. The measurement results are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that the contact treatment with trimethylvinylsilane was not carried out.
Obtained. The physical properties are shown in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that trimethylallylsilane was used instead of trimethylvinylsilane, and the degree of polymerization of trimethylallylsilane was 0.8 equivalent per transition metal catalyst component, and 474 g of polypropylene was obtained. The other measurement results are shown in Table 1.

Example 3 Commercially available highly active titanium trichloride (TA manufactured by Toho Titanium Co., Ltd.)
CS-21) was used as the transition metal catalyst component. Toluene 5
In 0 ml, 100 mg of the above titanium trichloride, 1.0 ml of diethylaluminum chloride, and 0.5 ml of ethyldimethylvinylsilane.
Contact treatment was carried out at 40 ° C. for 1 hour. Then add the slurry to an internal volume of 5
Put in an autoclave, propylene 1.8kg, hydrogen 4.4
Add NL and polymerize at 75 ° C for 4 hours to obtain polypropylene.
I got 940g. Propylene oxide 10
After treating at 100 ° C. for 1 hour in the presence of ml, the physical properties were measured as in Example 1. From the model experiment, the polymerization amount of ethyldimethylvinylsilane was 0.7 equivalent. The other measurement results are shown in Table 1.

Comparative Example 2 The same as Example 3 except that ethyldimethylvinylsilane was not used. 955 g of polypropylene Obtained. The physical properties are shown in Table 1.

Comparative Example 3 The same as Example 1 except that the amount of trimethylvinylsilane used was 0.5 mg. The polymerization amount of trimethylvinylsilane was less than 0.001 g, and 475 g of polypropylene was obtained. The physical properties are shown in Table 1.

〔effect〕

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

[Brief description of drawings]

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

Claims (3)

[Claims] 1. In 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, the catalyst is previously trialkylvinylsilane or trialkylallylsilane. A method for producing a highly crystalline polypropylene, which comprises polymerizing propylene after treatment. 2. The method according to claim 1, wherein trialkylvinylsilane or trialkylallylsilane is used in an amount of 0.01 equivalent times or more with respect to the transition metal catalyst component containing trivalent and / or tetravalent titanium halide. 3. A contact treatment under the condition that a trialkylvinylsilane or a trialkylallylsilane is reacted 0.001 equivalent times or more and 200 equivalent times or more with respect to a transition metal catalyst component containing trivalent and / or tetravalent titanium halide. The method according to claim 1.