JPH06298827A - Production of polypropylene - Google Patents

Abstract

PURPOSE:To produce polypropylene excellent in stiffness, moldability, etc., by polymerizing propylene in the presence of a catalyst comprising a solid catalyst component, an organoaluminum compd., a specific methoxysilane compd., and a specific ethoxysilane compd. CONSTITUTION:A catalyst is prepd. by combining a solid catalyst component contg. at least Mg, Cl, an arom. carboxylic ester (e.g. ethyl benzoate), and Ti, an organoaluminum compd. (e.g. trimethylaluminum), a methoxysilane compd. of formula I, and an ethoxysilane compd. of formula II. In those formulae, R<1> and R<3> are each a branched alicyclic or arom. hydrocarbon group; R<2> and R<4> are each a 1-3C linear hydrocarbon group; 0<t<=2 and 0<=Ss<=2 provided 1<=ft<=2; and 0<x<=2 and 0<=y<2 provided 1<=x+y<=2. The catalyst is used to polymerize propylene to produce polypropylene.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a propylene polymer. More specifically, the present invention relates to a method for efficiently producing a propylene polymer having high rigidity and excellent moldability.

[0002]

2. Description of the Related Art A solid catalyst component containing Mg, Cl, an aromatic carboxylic acid ester, and Ti, and a catalyst system comprising an organoaluminum compound and an alkoxysilane are used.
It is known that a polymer having high stereoregularity can be produced at a high yield by polymerizing propylene, and many methods have been proposed. The polymers obtained by these methods generally have a narrow molecular weight distribution, are inferior in fluidity at the time of melting, and have a problem that the strength of an injection molded article cannot be sufficiently obtained although the stereoregularity is high. As a method for solving this problem, for example, a method is known in which a plurality of polymerization vessels are used and propylene polymers having different molecular weights are produced in the respective polymerization vessels to obtain a polymer having a wide molecular weight distribution.

However, when these methods are used, it is necessary to use a plurality of polymerization vessels, the operation is complicated and laborious, the improvement of the molecular weight distribution is not sufficient, and the crystallinity is deteriorated. There were problems such as.
On the other hand, when polymerizing using a single polymerizer, a method of obtaining a propylene polymer having a controlled molecular weight distribution by simultaneously adding a plurality of alkoxysilanes satisfying a specific condition to a Mg-containing carrier-supported system catalyst, etc. Known (JP-A-2
-70708, JP-A-3-7703, etc.).
These methods, although a propylene polymer having a wide molecular weight distribution can be obtained in a single polymerization vessel to a certain extent, when compared with the case of polymerizing with a catalyst system using alkoxysilane alone,
It could not be said to be sufficiently satisfactory in terms of catalytic activity and stereoregularity.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a propylene polymer having improved moldability by using a homopolymerizer without lowering catalytic activity and stereoregularity. Is.

[0005]

The present inventors have found that Mg, C
Polymerization using a methoxysilane compound having a specific hydrocarbon group and an ethoxysilane compound having a specific hydrocarbon group together with a solid catalyst component containing 1, 1, an aromatic carboxylic acid ester, and Ti and an organoaluminum compound. It was found that the above problems can be solved by doing so.

That is, the present invention provides a solid catalyst component containing at least Mg, Cl, an aromatic carboxylic acid ester, and Ti as the component (A) (B) an organoaluminum compound (C ₁ ) of the formula R ¹ _t R ² _s Si ( OCH ₃ ) _4-ts (wherein R ¹ is a branched chain hydrocarbon group, an alicyclic hydrocarbon group,
Or an aromatic hydrocarbon group, R ² represents a linear hydrocarbon group having 1 to 3 carbon atoms, and t is 0 <t ≦
2, s is in the range of 0 ≦ s <2, and 1 ≦ s + t ≦ 2
A methoxysilane compound represented by the formula (C ₂ ) R ³ _x R ⁴ _y Si (OC ₂ H ₅ ) _4-xy (wherein R ³ is a branched chain hydrocarbon group, alicyclic ring) Formula hydrocarbon group,
Or an aromatic hydrocarbon group, R ⁴ represents a linear hydrocarbon group having 1 to 3 carbon atoms, and x is 0 <x ≦.
2, y is in the range of 0 ≦ y <2, and 1 ≦ x + y ≦ 2
Of ethoxysilane compound represented by the formula (4) is used to polymerize propylene using a catalyst system comprising an ethoxysilane compound.

The present invention will be described in detail below. Solid catalyst component (A) used in the present invention containing at least Mg, Cl, an aromatic carboxylic acid ester and Ti as components
Can be produced, for example, by reacting a magnesium compound, a titanium compound, a halogenating agent and an aromatic carboxylic acid ester in any order. Specific methods include a method in which activated magnesium halide, a titanium compound and an aromatic carboxylic acid ester are simultaneously or stepwise co-ground, or a magnesium compound in a uniform state is aromatic carboxylic acid ester or another electron donor. In the presence or absence of a body, a method of contacting a titanium compound with a precipitate obtained by causing a halogenating agent or a reducing agent to act in the presence of an aromatic carboxylic acid ester, etc. Available.

In the present invention, a particularly preferred solid catalyst composition
The method of producing the
Nesium component or hydrocarbyl oxymagnesium
A compound and a chlorosilane compound having an H-Si bond
Magnesium containing organic groups obtained by reacting
Um compounds, titanium compounds and aromatic carboxylic acid esters
It is a method of contacting with Ter.
60-11924, Japanese Patent Laid-Open No. 1-213311,
Japanese Patent Application Laid-Open No. 1-259003, Japanese Patent Application Laid-Open No. 2-28201,
Japanese Patent Application Laid-Open No. 2-138312, JP-A No. 2-138313,
Kaihei 4-23811, JP-A-4-216804
The method described in the report can be referred to. Of these catalyst components (A)
An example of the manufacturing method will be briefly described below. Hydrocarbon melt
Examples of the organic magnesium component soluble in the medium include compounds represented by the formula (M)_i(Mg)_j(R^Five)_p(R⁶)_q(OR⁷)_r (In the formula, M is group I, group II to group III of the periodic table.
Metal atom belonging to the group R ^Five, R⁶And R⁷Has 2 to 2 carbon atoms
20 hydrocarbon groups, i, j, p, q and r are
It is a number that satisfies the relationship. ) 0 ≦ i, 0 <j, 0 ≦ p, 0 ≦ q, 0 <r, ki + 2j
= P + q + r (where k is the valence of M) in the hydrocarbon solvent
Complexation of organomagnesium containing soluble alkoxy groups
You can use compound. Then has an H-Si bond
As the chlorosilane compound, HSiCl₃, HSi
Cl₂CH₃, HSiCl₂C₂H_Five, HSiCl₂n-
C₃H₇, HSiCl₂iso-C₃H₇, HSiCl₂
n-C_FourH₉, HSiCl₂C₆H_Five, HSiCl₂(4
-Cl- C₆H_Four), HSiCl₂CH = CH₂, SiC
l₂CH₂C₆H _Five, HSiCl₂(1-C_TenH₇), HS
iCl₂CH₂CH = CH₂, H₂SiClCH₃, H
₂SiClC₂H_Five, HSiCl (CH₃)₂ , HSiC
l (C₂H _Five)₂ , HSiClCH₃(iso-C₃H₇), HS
iClCH₃(C₆H_Five), HSiCl (C₆H_Five)₂ Etc.
Selected from these compounds and these compounds
Chlorosilane compound consisting of a mixture of
Yes, trichlorosilane, monomethyldichlorosilane,
Dimethylchlorosilane, ethyldichlorosilane, etc. are preferred.
, Especially trichlorosilane, monomethyldichlorsila
Is preferred.

Next, the reaction between the organomagnesium component soluble in a hydrocarbon solvent and the chlorosilane compound will be described. In the reaction, a chlorosilane compound is previously added to an inert reaction medium, for example, n-hexane, an aliphatic hydrocarbon such as n-heptane, an aromatic hydrocarbon such as benzene, toluene and xylene, an alicyclic carbon such as cyclohexane and methylcyclohexane. It is preferable to use hydrogen after diluting it with chlorinated hydrocarbon such as 1,2-dichloroethane, o-dichlorobenzene, dichloromethane, or a mixed medium thereof.

The reaction temperature is not particularly limited, but it is preferably in the range of 40 ° C. or higher and lower than the boiling point of the reaction medium in order to accelerate the reaction. The composition of the solid component obtained by the above reaction and the structure thereof vary depending on the type of the starting materials and the reaction conditions, but from the result of the composition analysis, about 0.1 to 1.5 mmol of Mg per 1 g of the solid component is obtained. It is presumed to be an organic group-containing magnesium compound having a -C bond or having about 0.1 to 1.5 mmol of Mg-C bond and about 0.5 to 3.0 mmol of alkoxy group.

Titanium compounds that can be used to produce the solid catalyst component include, for example, titanium tetrachloride, titanium tetrabromide,
Examples thereof include titanium tetraiodide, ethoxytitanium trichloride, propoxytitanium trichloride, butoxytitanium trichloride, dibutoxytitanium dichloride, tributoxytitanium chloride, and the like, with titanium tetrachloride being particularly preferred. Examples of aromatic carboxylic acid esters include, for example, esters of monocarboxylic acids such as benzoic acid, P-toluic acid and P-anisic acid such as methyl, ethyl, propyl and butyl, and dimethyl phthalate, diethyl and di-n. -Propyl,
Examples thereof include dicarboxylic acid diesters such as diiso-propyl, din-butyl, diiso-butyl, din-heptyl, di2-ethylhexyl and dioctyl. Further, these aromatic carboxylic acid esters may be used alone or in combination.

As the method for preparing the solid catalyst component (A) in the present invention, the method described in the above-mentioned patent publication can be used. For example, (I) the solid component, titanium compound and aromatic carboxylic acid ester are used. Method of contacting at the same time,
(II) First, a method in which any two are brought into contact with each other, and then the remaining components are brought into contact with each other, and (III) the solid component, the titanium compound, and the aromatic carboxylic acid ester are simultaneously brought into contact with each other, and further brought into contact with the titanium compound. Methods etc. can be used. Further, as the contacting means, any means such as contacting in liquid phase or gas phase, contacting in combination with contact in liquid phase or gas phase and pulverization may be used.

The composition of the obtained solid catalyst component and its structure vary depending on the kind of the starting materials and the contact conditions, but from the composition analysis value, the ratio of titanium in the solid catalyst of about 1 to 10% by weight is obtained. It is a solid catalyst having a surface area of 50 to 300 m ² / g. Examples of the organoaluminum compound (B) used in the present invention include trialkylaluminums such as trimethylaluminum, triethylaluminum, triisobutylaluminum and trihexylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, alkylaluminum halides such as ethylaluminum sesquichloride, Furthermore,
Alkyl aluminum alkoxides such as diethyl aluminum ethoxide, diethyl aluminum butoxide, and diethyl aluminum phenoxide can be used, and a mixture thereof can also be used.

The formula R ¹ _t R ² _s Si (OCH ₃ ) _4-ts used in the present invention (wherein R ¹ , R ² , s, and t are as described above).
Examples of the methoxysilane compound (C ₁ ) represented by are phenyltrimethoxysilane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, diisopropyldimethoxysilane, isobutyltrimethoxysilane, diisobutyldimethoxysilane, isobutylisopropyldimethoxysilane, ditert- Butyldimethoxysilane, tert-butylmethyldimethoxysilane, tert-butylethyldimethoxysilane, tert-butyl n-propyldimethoxysilane, cyclohexyltrimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylisopropyldimethoxysilane, dicyclopentyldimethoxysilane, etc. Particularly preferred is dimethoxysilane.

Formula R ³ _x R ⁴ _y Si (OC ₂ H ₅ ) _4-xy (wherein R ³ , R ⁴ , x, and y are as described above)
Examples of the ethoxysilane compound (C ₂ ) represented by are phenyltriethoxysilane, diphenyldiethoxysilane, phenylmethyldiethoxysilane, diisopropyldiethoxysilane, isobutyltriethoxysilane, diisobutyldiethoxysilane, isobutylisopropyldiethoxy. Silane, di-tert-butyldiethoxysilane, tert-butylmethyldiethoxysilane, tert-butylethyldiethoxysilane, tert-butyl n-propyldiethoxysilane cyclohexyltriethoxysilane,
Examples thereof include cyclohexylmethyldiethoxysilane and cyclohexylisopropyldiethoxysilane, with diethoxysilane being particularly preferred.

When (C ₁ ) and (C ₂ ) used for the polymerization are selected from the above, (A), (B), (C ₁ ),
And the melt index (MFI; load at 230 ° C. of 230 ° C.) of the propylene polymer obtained when propylene is polymerized using a catalyst system consisting of (C ₂ ).
Of the amount of the molten resin discharged for 10 minutes when adding the) to the melt index of the propylene polymer obtained by polymerizing only (A), (B) and (C ₁ ) under the same polymerization conditions. , 1 to 4.5 are preferably selected. When this ratio is out of the above range, it is difficult to obtain a propylene polymer having an excellent balance between moldability and rigidity as in the present invention.

The catalyst components (A), (B) in the present invention,
The use ratio of (C ₁ ) and (C ₂ ) is 1 to 3000 mmol, preferably 5 to 1000, in terms of aluminum atom in (B), relative to 1 g of the solid catalyst component (A).
The amount of (C ₁ ) and (C ₂ ) used is in the range of 0.01 to 1,000 mmol, preferably 0.05, in terms of the total amount converted to silicon atoms in (C ₁ ) and (C ₂ ).
It is preferably used in the range of up to 100 mmol.
The mixing ratio of the (C ₁₎ and _{(C 2), (C 1} ) usage M1: molar ratio of the amount M2 of (C _2), 0.
A range of 9: 1 to 0.1: 1 is preferred. When the used molar ratio of (C ₁ ) to (C ₂ ) exceeds 0.9,
A sufficient effect of improving the moldability cannot be obtained.

These catalyst components (A), (B), (C ₁ )
All of (C ₂ ) may be used in contact with each other at the time of polymerization, or may be used by contacting with any one of the three before polymerization and then contacting with the other one. It may be in an inert gas atmosphere or an olefin atmosphere. Further, in order to control the molecular weight of the polymer, it is possible to add hydrogen, halogenated hydrocarbon or an organometallic compound which easily causes chain transfer.

The polymerization method applicable to the present invention is not particularly limited, but it is preferable to use polymerization in a liquid monomer and gas phase polymerization. In suspension polymerization, a catalyst is introduced into a reactor together with a polymerization solvent such as hexane and an aliphatic hydrocarbon such as heptane, and propylene is injected under an inert gas atmosphere at a pressure of 1 to ²⁰ Kg / cm ² at room temperature to 150 ° C. The polymerization can be carried out at the temperature of. In the polymerization in liquid monomer, propylene can be polymerized in liquid propylene in the presence of a catalyst at a temperature of room temperature to 90 ° C. and a pressure of 10 to 45 Kg / cm ² .

On the other hand, in the gas phase polymerization, the contact between propylene and the catalyst is satisfactory under the condition that propylene is a gas and in the absence of a solvent at a pressure of 1 to 50 Kg / cm ² and at a temperature of room temperature to 120 ° C. Polymerization can be carried out by taking measures such as mixing using a fluidized bed, a moving bed or a stirrer. For example, when using a gas phase polymerization apparatus having a stirring fluidized bed, various types can be used, but it is particularly preferable to have a helical stirring blade with a Froude number of 1 to 3 at the center. By supplying a propylene alone or propylene and hydrogen continuously or intermittently to the polymerization zone and supplying each component of the catalyst to the polymerization zone. A gas phase polymerization apparatus having a basic constitution that polymerization is initiated and the obtained polymer is continuously or intermittently taken out of the polymerization zone can be used.

The polymerization conditions are, for example, 40 to 9
At a temperature of 5 ° C. and a pressure of 10 to 35 Kg / cm ² (gauge pressure), propylene alone or propylene and hydrogen are continuously or intermittently supplied to the polymerization zone to remove the heat of polymerization generated by the polymerization and to perform the polymerization. The unreacted propylene is withdrawn from the polymerization zone, liquefied and fed again to the polymerization zone in liquid form, and the obtained polymer is continuously or intermittently discharged from the polymerization zone. A method is used in which the polymerization is continued by the method consisting of taking out.

A method of this kind is described in US Pat.
Reference may be made to the methods and examples thereof described in 330645, 4442271, and GB 1032945. According to the invention, the proportion of 1,2,4-trichlorobenzene insoluble matter at 120 ° C. is 25% by weight or more, preferably 30%.
A polypropylene is obtained which is more than weight%.

1, 2 at 120 ° C. used in the present invention
4-Trichlorobenzene insoluble matter is measured by Polymer
Preprints Am. Chem. Soc. 18, 182 (1977), but more specifically the following method is used. That is, a predetermined amount of a propylene polymer and an antioxidant were heated and dissolved in 1,2,4-trichlorobenzene, and this solution was packed in a stainless steel column filled with sea sand and maintained at a temperature of 160 ° C. The column temperature is lowered to 30 ° C. to precipitate the polymer and fully crystallize it. The column is heated to 120 ° C., and a sufficient amount of 1,2,4-trichlorobenzene so that the total amount of soluble components at this temperature is eluted is continuously flown. After that, the temperature was further raised to 160 ° C., and similarly a sufficient amount of 1,2,4-trichlorobenzene was flown, and at 120 ° C., it was insoluble and 160 ° C.
And collect the soluble part. This 1,2,4-trichlorobenzene solution recovers the polymer by adding a large amount of methanol. The weight percentage of the recovered propylene polymer initially used was 1 at 120 ° C.
The content is insoluble in 2,4-trichlorobenzene.

The MFI of the propylene polymer obtained according to the present invention is in the range of 5 to 200, especially 8 to 150. The polymer obtained in the present invention is a variety of phenolic stabilizers, organic phosphite stabilizers, aluminum benzoate nucleating agents, sorbitol nucleating agents, sodium phosphate salt nucleating agents and higher fatty acid metal salts. Additives, nucleating agents and the like can be blended and used for various moldings.

[0025]

EXAMPLES The present invention will be described below with reference to examples. Each measured value used in the examples is measured according to the method described below. <MFI> ASTM D-1238 <Boiling heptane extraction residue> This means the percentage of the extraction residue after the obtained polymer is extracted with boiling n-heptane for 6 hours, relative to the weight of the polymer before extraction.

<Spiral Flow Length> P-EPQ (manufactured by Sand Co.) was added to the obtained polymer powder as an additive.
What was added with 05 wt% and 0.1 wt% of calcium stearate and granulated at a temperature of 230 ° C. using a twin-screw extruder was measured under the following conditions. Measurement conditions Injection molding machine IS-150EN Molding temperature 230 ° C. Injection pressure 1400 kg / cm ² Mold 2.5φ semi-circular mold <Flexural modulus> Injection molded under the same conditions as above, left at 23 ° C. for 72 hours. After that, ASTM D-790
It was evaluated according to.

[0027]

Example 1 (I) Synthesis of Organomagnesium Component Containing Alkoxy Group Composition formula AlMg ₆ (C ₂ H ₅ ) ₃ (n-C ₄ H ₉ ) ₁₂ synthesized in advance from triethylaluminum and dibutylmagnesium
An n-heptane solution containing 250 mmol (based on magnesium) of the organomagnesium complex component shown in was placed in a 1-liter flask sufficiently replaced with nitrogen, and n-butyl was added from a dropping funnel while cooling and stirring in an ice bath. Alcohol 22.8 cc (250 mmol) was slowly added dropwise over 1 hour to react, and further reacted at room temperature for 1 hour with stirring. A relatively viscous colorless and transparent solution was obtained, which was analyzed to find that the solution contained n-butoxy groups of 0.
It contained 96 mol, and had a magnesium concentration of 1.0 mol / liter.

(II) Synthesis of Magnesium-Containing Solid by Reaction with Chlorosilane Compound Trichlorosilane was added as a 1 mol / liter n-heptane solution to a 1-liter flask sufficiently replaced with nitrogen.
The amount of 00 mmol was charged, the temperature was maintained at 65 ° C. with stirring, the total amount of the n-heptane solution of the above-mentioned organomagnesium component containing an alkoxy group was added over 1 hour, and the mixture was further reacted at 65 ° C. for 1 hour with stirring. The white solid formed is filtered off, washed thoroughly with n-hexane and dried to give a white solid 2
9.5 g was obtained. As a result of analyzing this solid substance, solid 1
In g, Mg 7.45 mmol, CL 14.2 mmol,
It contained a butoxy group of 2.32 mmol and had a specific surface area of 193 m ² / g as measured by the BET method.

(III) Synthesis of Solid Catalyst Component Titanium tetrachloride (2) was placed in a 500 cc flask containing 10 g of the solid component obtained in (II) and sufficiently replaced with nitrogen.
0 cc and 200 cc of toluene were added, and further 2.0 cc (7.5 mmol) of di-n-butyl phthalate was added and contacted at room temperature for 1 hour with stirring. After contact, remove the supernatant,
Further, 80 cc of titanium tetrachloride was added and the temperature was raised, and the mixture was further contacted at a temperature of 120 ° C. for 3 hours. After the reaction was completed, the solid was separated by hot filtration, and 200 cc of toluene heated to 100 ° C.
With n-hexane and then washed with n-hexane to obtain a solid catalyst component. When a part of this was taken and analyzed, the Ti content in the solid catalyst component was 1.5% by weight.

[Polymerization] Using a reactor equipped with a stirrer having an internal volume of 200 L, which has a stirring bed made of 50 kg of finely powdered polypropylene, and under stirring at a Froude number of 2.2, a polymerization temperature of 90 ° C. and a polymerization pressure of 32 kg / Polymerization was initiated by continuously feeding the solid catalyst component, triethylaluminum, diisopropyldimethoxysilane and diphenyldiethoxysilane while propylene and hydrogen were continuously fed so as to be maintained under the condition of cm ² . At that time, the polymer production rate was controlled to 20 kg / hr and the hydrogen concentration in the gas phase was controlled to 0.1 mol%. The feed ratio of each catalyst component is as follows:
The molar ratio of triethylaluminum to the amount is 1:40
0, the molar ratio of ethylaluminum to Si in the alkoxysilane is 1:10, and the molar ratio of diisopropyldimethoxysilane and diphenyldiethoxysilane is 0.
Polymerization was carried out under the condition of 8: 1.

Solid catalyst component 1 g The yield of the obtained propylene polymer was 35.2 Kg, the boiling n-heptane extraction residual ratio of the obtained propylene polymer was 98.5%, and the MFI was 16.5. 1,2,4-at 120 ° C
The trichlorobenzene insoluble content was 31.4% by weight.
The results of measuring the spiral flow length and the bending elastic modulus are shown in Table 3.

[0032]

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that cyclohexylmethyldimethoxysilane and phenyltriethoxysilane were used as the alkoxysilane compound used in Example 1 and the mixing ratio of both was changed to 1: 1. Solid catalyst component 1 g The amount of propylene polymer produced was 30.3 Kg, the boiling n-heptane extraction residual rate of the obtained propylene polymer was 97.8%, and the MFI
Of 1,2,4-trichlorobenzene insoluble matter at 8.5 and 120 ° C was 21.9% by weight. The other results are shown in Table 4.

[0033]

Examples 2 to 6 Table 1 shows the alkoxysilane compounds used.
Alternatively, a propylene polymer was obtained in the same manner as in Example 1 except that the combination and the molar ratio shown in Table 2 were changed. The MFI of the obtained polymer was 30.0, 15.6,
It was 24.7, 19.6 and 23.4. The other results are shown in Table 3 or Table 4.

[0034]

Comparative Example 2 A propylene polymer was obtained in the same manner as in Example 1 except that the alkoxysilane compounds used were changed to the combinations and the molar ratios shown in Table 2. The results of evaluating the obtained polymer are shown in Table 4.

[0035]

Reference Example 1 Using the solid catalyst component obtained in Example 1,
Polymerization of propylene was carried out under the same polymerization conditions as in Example 1 except that methoxysilane and ethoxysilane used in Examples 1 to 5 and Comparative Examples 1 and 2 were used alone. The MFI of the resulting propylene polymer is shown in Table 5.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

[0040]

[Table 5]

[0041]

EFFECTS OF THE INVENTION According to the present invention, even when the polymerization is carried out by using only the homopolymerization tank, propylene excellent in the balance between rigidity and moldability with high efficiency without lowering the catalytic activity and stereoregularity. A polymer can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing an example of a method for producing a propylene polymer according to the present invention.

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[Procedure amendment]

[Submission date] May 14, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

[0038]

[Table 3]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

[0039]

[Table 4]

Claims (3)

[Claims] 1. At least Mg and C as the component (A)
(B) Organoaluminum compound (C ₁ ) Formula R ¹ _t R ² _s Si (OCH ₃ ) _4-ts (wherein R ¹ is a branched chain carbonization) Hydrogen group, alicyclic hydrocarbon group,
Or an aromatic hydrocarbon group, R ² represents a linear hydrocarbon group having 1 to 3 carbon atoms, and t is 0 <t ≦
2, s is in the range of 0 ≦ s <2, and 1 ≦ s + t ≦ 2
A methoxysilane compound represented by the formula (C ₂ ) R ³ _x R ⁴ _y Si (OC ₂ H ₅ ) _4-xy (wherein R ³ is a branched chain hydrocarbon group, alicyclic ring) Formula hydrocarbon group,
Or an aromatic hydrocarbon group, R ⁴ represents a linear hydrocarbon group having 1 to 3 carbon atoms, and x is 0 <x ≦.
2, y is in the range of 0 ≦ y <2, and 1 ≦ x + y ≦ 2
Of the ethoxysilane compound represented by the formula (1) is used to polymerize propylene using a catalyst system comprising an ethoxysilane compound. 2. The solid catalyst component (A) is a reaction product of (a) a hydrocarbon-soluble organomagnesium component and a chlorosilane compound having an H—Si bond, (b) an aromatic carboxylic acid ester, and (c) titanium. The method for producing polypropylene according to claim 1, which is a solid catalyst component containing at least Mg, Cl, an aromatic carboxylic acid ester, and Ti obtained by mutual contact with a compound. 3. The method for producing polypropylene according to claim 1, wherein the molar ratio of the amount of the methoxysilane compound (C ₁ ) to the amount of the ethoxysilane compound (C ₂ ) used is in the range of 0.1 to 0.9. .