JPH0784485B2 - New polymerization method of propylene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel 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 impact resistance, especially impact resistance at low temperature is poor, impact resistance is improved by block copolymerizing with other olefins such as ethylene. (For example, Japanese Patent Publication No. 44-2062)
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, according to the present invention, in a method for polymerizing propylene using a catalyst composed of a transition metal catalyst component containing trivalent and / or tetravalent titanium halide and an organoaluminum compound, the catalyst is previously subjected to contact treatment with t-butylstyrene. A method for producing a highly crystalline polypropylene, which comprises polymerizing propylene.

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 improver 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 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), Journ
al of Macromolecular Science-Reviews in Maclomole
cular Chemistry and Physics C24 (3) 355-385 (198
4) Same C25 (1) 57-97 (1985)) As the stereoregularity improver or electron-donating compound, an oxygen-containing compound such as an ether, ester, orthoester or alkoxysilicon compound can be preferably used. 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 catalytic treatment with t-butylstyrene. At this time, the use ratio of the organoaluminum compound / transition metal catalyst component may be the same as the ratio in the subsequent polymerization of propylene, or may be a smaller amount, and the amount ratio is 0.5-1000. Is common. It is also possible to allow a stereoregularity improver to be present at that time, and the preferable ratio thereof is 0.01-
300. There is no particular limitation on the contact treatment temperature and the contact treatment time, but it is generally the same as or lower than the temperature in the subsequent polymerization of propylene, and preferably 0.001 equivalent of t-butylstyrene per transition metal catalyst component. It is to treat under the conditions that the above reaction occurs. The contact treatment is pentane, hexane, heptane, octane, nonane,
It is carried out in an inert medium such as decane, benzene, toluene, xylene, ethylbenzene, or a mixture thereof for the Ziegler-Natta catalyst, and unreacted t
It is also possible to remove and wash butylstyrene, and then add an organoaluminum compound and use it for the polymerization of propylene. The amount of t-butylstyrene used is preferably 0.01 equivalent times or more per transition metal catalyst component. If it is 0.01 equivalent times or less, 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, t-butylstyrene may be any of para-, meta-, and ortho-forms, preferably para-form.

〔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, except for the supernatant, titanium tetrachloride is similarly used.
1.5 and toluene 1.5 were added, the mixture was stirred at 100 ° C. for 30 minutes, the supernatant was removed, and the solid was washed with n-heptane (4) repeatedly 10 times. One part of the obtained solid catalyst slurry was sampled. The titanium content was analyzed and found to be 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, and para-t-butylstyrene 0.4 ml were added, and the mixture was stirred at 40 ° C for 30 minutes and then triethylaluminum.
0.05 ml was added. 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 75 ° C for 2 hours. After the polymerization reaction, unreacted propylene was purged and the polymer was taken out at 80 ° C, 60 mmHg
And dried for 12 hours. Intrinsic viscosity (hereinafter abbreviated as η) measured with a tetralin solution at 135 ° C with 475 g of powder obtained
And the ratio of the extraction residual ratio when extracted with a Soxhlet extractor with boiling n-heptane for 6 hours (abbreviated as II below)
Then measure the phenolic stabilizer in a 10/1000 weight ratio,
Further, calcium stearate was added in a weight ratio of 15/1000, and the mixture was granulated, the melt flow index was measured, and an injection sheet having a thickness of 1 mm was prepared, and the bending 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. When the polymerization amount of para-t-butylstyrene with respect to the transition metal catalyst component was measured using a model experiment without propylene polymerization, it was found to be 1.3 equivalents relative to the transition metal catalyst component. The measurement results are shown in Table 1.

Comparative Example 1 Polypropylene was obtained in the same manner as in Example 1 except that the contact treatment with para-t-butylstyrene was not performed.
5g was obtained. The physical properties are shown in Table 1.

Example 2 The amount of para-t-butylstyrene was adjusted to 1 ml, the slurry was washed after the reaction, and 0.128 ml of diethylaluminum chloride, 0.06 ml of methyl P-toluate and 0.08 ml of triethylaluminum were added to the insoluble matter, and the autoclave was charged. The same procedure as in Example 1 was carried out except for the addition. The amount of polymerization per transition metal catalyst component was 2.1 equivalents, and 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
40 ml of the above titanium trichloride (100 mg), diethylaluminum chloride (1.0 ml) and para-t-butylstyrene (0.5 ml) in 0 ml.
Contact treatment was carried out at 0 ° C. for 1 hour. Then add the slurry to an internal volume of 5
Put in autoclave, propylene 1.8kg, hydrogen 4.4NL
Was added to carry out a polymerization reaction at 75 ° C. for 4 hours, then 10 ml of propylene oxide was added and treated at 100 ° C. for 30 minutes to obtain 920 g of polypropylene. A model experiment was conducted to measure the polymerization amount of para-t-butylstyrene with respect to the transition metal catalyst component, and it was 0.9 equivalent per pair of transition metal catalyst component. The measurement results are shown in Table 1.

Comparative Example 2 Example 3 except that no para-t-butylstyrene was used.
In the same manner as described above, 955 g of polypropylene was obtained. The physical properties are shown in Table 1.

Comparative Example 3 The procedure of Example 1 was repeated except that the amount of para-t-butylstyrene used was 0.5 mg. The polymerization amount of para-t-butylstyrene 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 catalyst according to the present invention.

Claims (3)

[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 contact-treated with t-butylstyrene. A method for producing highly crystalline polypropylene, which comprises polymerizing propylene afterwards. 2. The method according to claim 1, wherein t-butylstyrene 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 t-butylstyrene is reacted 0.001 equivalent times to 200 equivalent times with respect to a transition metal catalyst component containing trivalent and / or tetravalent titanium halide. The method according to claim 1.