JPH0830095B2 - Process for producing olefin polymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an olefin polymer. Specifically, a specific α-olefin is prepolymerized, and then an α-olefin such as propylene is subjected to main polymerization to obtain an α-olefin polymer having excellent transparency and rigidity, and having high stereoregularity and bulk density. It relates to a method of obtaining activity.

[Conventional technology]

Conventionally, using a titanium-containing solid catalyst component containing titanium trichloride or a magnesium compound as a carrier, α having 3 or more carbon atoms has been used.
It is well known to pre-polymerize an olefin at a relatively low temperature with a small amount of α-olefin prior to polymerizing the olefin.

[Problems to be solved by the invention]

In Japanese Examined Patent Publication No. S57-45244, bulk density and stereoregularity are obtained by prepolymerizing a catalyst composed of a titanium-containing solid catalyst component supported on a magnesium compound and an organoaluminum compound with a small amount of propylene, and then polymerizing propylene. A method for obtaining a propylene polymer having improved properties with high activity has been proposed. However, this method can hardly improve the transparency of the propylene polymer.

On the other hand, in Japanese Patent Publication No. 45-32430, a catalyst composed of titanium trichloride and an organoaluminum compound is used in a small amount.
A method of obtaining a propylene copolymer having good transparency by prepolymerizing with -methylbutene-1 and then copolymerizing propylene and an α-olefin having 4 or more carbon atoms such as hexene-1. In Japanese Patent Laid-Open No. 61-151204, too, a catalyst composed of titanium trichloride and an organoaluminum compound is prepolymerized with a small amount of 3-methylbutene-1 and then propylene is polymerized to have high rigidity, and many cracks are formed on the surface. A method of obtaining an existing propylene polymer powder is presented.

However, in these methods, while the physical properties of the propylene polymer are improved, titanium trichloride having low polymerization activity is used as a catalyst component, so a step of removing the catalyst residue after polymerization becomes essential, and it is industrially sufficient. It was hard to say that it was a satisfactory method.

Therefore, there is a demand for development of a method for producing a polymer which simultaneously has these various effects in polymerization using a solid catalyst component containing magnesium, titanium, halogen and an electron donating compound as essential components.

[Means for solving problems]

As a result of intensive studies to solve the problems of the prior art, the present inventors have found that a catalyst composed of a catalyst component containing magnesium, titanium, a halogen and an electron donating compound as an essential component and an organoaluminum compound is used. -Methylbutene-1, preferably propylene having excellent transparency and rigidity, and good stereoregularity and bulk density by prepolymerization with a mixture of 3-methylbutene-1 and another α-olefin having 3 to 20 carbon atoms. It has been found that a polymer can be obtained, and the present invention has been completed.

That is, the gist of the present invention is to provide a solid catalyst component (A) containing magnesium, titanium, a halogen and an electron-donating compound as essential components and a compound (B) represented by the general formula AlR ⁵ _j X _3-j.
(Wherein R ⁵ represents a hydrocarbon group having 1 to 20 carbon atoms, X represents a halogen, and j represents a number of 2 to 3) in the presence of 3-methylbutene-1, Alternatively, a mixture of 3-methylbutene-1 and an olefin having 3 or more carbon atoms is prepolymerized to obtain a prepolymerized component, and then an olefin having 3 or more carbon atoms is added in the presence of the prepolymerized component and, if necessary, an additional compound (B). A method for producing an olefin polymer is characterized by homopolymerization or copolymerization.

 Hereinafter, the present invention will be described in detail.

The solid catalyst component (A) in the present invention is contacted or reacted with at least a magnesium compound, a titanium compound and an electron donating compound, and if necessary, an auxiliary agent such as a silicon compound or a halogenating agent, temporarily or stepwise. The composite solid containing all conventionally known magnesium, titanium, halogen, and electron donating compounds obtained by the above is used. Specifically, (1) a method in which dialkoxy magnesium, a titanium compound and an electron donating compound are reacted in an arbitrary order, and then appropriately washed with liquid hydrocarbon (2) magnesium chloride, a titanium compound and an electron donating compound After contacting and reacting with each other in any order, and then appropriately washing with liquid hydrocarbon (3) reaction product of organomagnesium compound with water, alcohol, phenol or silanol, titanium compound and electron donating compound It is produced by a method such as a method of appropriately reacting with a liquid hydrocarbon after the reaction in the order of.

Furthermore, during these reactions, silicon compounds, halogen compounds, alcohols, or inert solids such as SiO ₂ , Al
₂ O ₃ , polypropylene, polyethylene, poly-3 methylbutene-1, poly-4 methylpentene-1, TiO ₂ , B
₂ O ₃ , CaCO ₃ or the like may be added.

The solid catalyst component (A) is preferably a compound represented by the general formula Mg
(OR ¹ ) _2-n X _n (wherein R ¹ represents an alkyl group, an aryl group or an aralkyl group, X represents halogen, and n represents 0 ≦ n ≦ 2), a general formula Ti (OR ² ) _m
X _4-m (In the formula, R ² represents an alkyl group, an aryl group or an aralkyl group, X represents halogen, and m represents 0 ≦ m ≦ 4.)
It is a composite solid containing magnesium, titanium, halogen and an electron donating compound obtained by reacting a titanium compound represented by and an electron donating compound.

As the magnesium compound represented by the general formula Mg (OR ¹ ) _2-n X _n , specifically, MgCl ₂ , Mg (OCH ₃ ) Cl, Mg (OC ₂ H ₅ )
Cl, Mg (OC ₃ H ₇ ) Cl, Mg (OC ₄ H ₉ ) Cl, Mg (OC ₆ H ₅ ) Cl, Mg (OC
_{H 3) 2, Mg (OC} 2 H 5) 2, Mg (OC 3 H 7) 2, Mg (OC 4 H 9) 2, Mg (OC
₆ H ₅ ) ₂ , Mg (OCH ₂ C ₆ H ₅ ) ₂ , Mg (OC ₂ H ₅ ) (OC ₄ H ₉ ), Mg (OC ₂ H ₅ ).
(OC ₆ H ₅ ), Mg (OC ₄ H ₉ ) (OC ₆ H ₅ ), Mg (OC ₆ H ₄ CH ₃ ) _{2 and the} like. These can also be mixed and used.
In addition, as other carrier raw materials, organomagnesium compounds, MgO, Mg (OH) ₂ , Mg (OH) Cl, Mg carbonate, Mg salts of organic acids, Mg silicates, Mg aluminates and the like can also be used.

Specific examples of the titanium compound represented by the general formula Ti (OR ² ) _m X _4-m include TiCl ₄ , TiBr ₄ , TiI ₄ , Ti (OCH ₃ ) Cl ₃ , and T.
i (OC ₂ H ₅ ) Cl ₃ , Ti (OC ₄ H ₉ ) Cl ₃ , Ti (OC ₆ H ₅ ) Cl ₃ , Ti (OCH ₃ ) _{2
Cl 2, Ti (OC 2 H} 5) 2 Cl 2, Ti (OC 4 H 9) 2 Cl 2, Ti (OC 6 H 5) 2 Cl 2,
_{Ti (OCH 3) 3 Cl,} Ti (OC 2 H 5) 3 Cl, Ti (OC 4 H 9) 3 Cl, Ti (OC 6 H 5)
₃ Cl, Ti (OCH ₃ ) ₄ , Ti (OC ₂ H ₅ ) ₄ , Ti (OC ₄ H ₉ ) ₄ , Ti (OC
₆ H ₅ ) ₄ , and the like. Further, in addition to this, it is represented by the general formula Ti (OR ³ ) _l X _3-l (wherein R ³ is an alkyl group, an aryl group or an aralkyl group, X is a halogen, and l is 0 ≦ l ≦ 3). A titanium compound can also be used. These may be mixed and used.

Examples of the electron donating compound generally include a phosphorus-containing compound, an oxygen-containing compound, a sulfur-containing compound, a nitrogen-containing compound, and the like. Of these, oxygen-containing compounds are preferred.

Examples of the oxygen-containing compound include ethers, esters, ketones, acid anhydrides and the like.

Preferably, ethyl acetate, methyl propionate, ethyl acrylate, ethyl oleate, ethyl stearate, ethyl phenyl acetate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, methyl toluate, ethyl toluate, Propyl toluate, butyl toluate, methyl ethyl benzoate, ethyl ethyl benzoate, ethyl xylene carboxylate, methyl anisate,
Esters of carboxylic acids such as ethyl anisate, methyl ethoxybenzoate, ethyl ethoxybenzoate, ethyl cinnamate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, dioctyl phthalate or γ-butyl. Examples thereof include cyclic esters such as lactones and acid anhydrides such as maleic anhydride and phthalic anhydride. Further, a silicon compound having a Si—OR ⁴ , Si—OCOR ⁴ or Si—NR ⁴ ₂ bond (in the formula, R ⁴ represents a hydrocarbon group having 1 to 20 carbon atoms) is also preferably used.

The composition of the titanium-containing solid catalyst component is halogen /
Titanium (molar ratio) is 1 to 5000, electron donating compound / titanium (molar ratio) is 0.1 to 5, titanium / magnesium (molar ratio) is 0.01 to 1.0, and titanium content (% by weight) in the solid catalyst component is 0.01. -20, preferably halogen / titanium (molar ratio) 3-100, electron donating compound / titanium (molar ratio) 0.5-3, titanium / magnesium (molar ratio)
0.02 to 0.5, the titanium content (% by weight) in the solid catalyst component is
It is in the range of 0.1 to 10.

Examples of the compound (B) as a catalyst component used in the method of the present invention include compounds represented by the general formula AIR ⁵ _j X ₃ -j. In the above formula, R ⁵ represents a hydrocarbon group having 1 to 20 carbon atoms, particularly preferably an aliphatic hydrocarbon group. X is halogen and j is a number of 2-3. Specific examples of the organoaluminum compound include triethylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum monochloride and the like, but preferably trialkylaluminum is used.

The electron-donating compound (C) used as necessary is selected from the group of electron-donating compounds used in the production of the titanium-containing solid catalyst component (A), but is preferably an aromatic carboxylic acid ester. , A silicon compound containing a Si—O—C bond, a silicon compound containing an Al—O—Si—C bond, and the like.

In the prepolymerization, a catalyst comprising the solid catalyst component (A), the compound (B) represented by the general formula and optionally an electron donating compound (C), and usually an inert hydrocarbon or liquefied α
-In a solvent such as olefin, 3-methylbutene-1, or 3-methylbutene-1 and an α-olefin having 3 to 20 carbon atoms, preferably propylene, butene-1, hexene-
It is carried out by contacting a mixture with 1, octene-1, etc. If prepolymerization is carried out only with 3-methylbutene-1, the polymerization rate of 3-methylbutene-1 is very low, so that it is usually necessary to lengthen the prepolymerization time, and further the activity of propylene polymerization to be carried out subsequently. However, prepolymerization with a mixture of 3-methylbutene-1 and another α-olefin having 3 to 20 carbon atoms also requires a short prepolymerization time, and the subsequent propylene polymerization It is more preferable because the activity does not decrease so much.

As the composition of the mixture, 3-methylbutene-1 / other α-olefin (molar ratio) is 0.01 to 10,000, preferably
The range is 0.1 to 1000, more preferably 1 to 100. The prepolymerization temperature is usually 0 to 100 ° C., preferably 20 to 80 ° C., more preferably more than 50 ° C., and the prepolymerization amount is usually 0.01 to 100 g per 1 g of the solid catalyst component (A), total polymerization. The amount is selected from the range of 0.001 to 30% by weight. Outside of such a range, the effects of the present invention cannot be sufficiently obtained, which is not preferable.

The proportion of each component of the catalyst used during prepolymerization is not particularly limited, but usually the molar ratio of titanium in the catalyst component (A) to metal in the component (B) to electron donating compound of the component (C) is 1 : 0.1
˜10: 10 to 10, preferably 1: 0.5 to 3: 0 to 3.

After the prepolymerization, the polymer-containing solid catalyst component is washed with an inert hydrocarbon or is not washed to be used for the main polymerization of an olefin.

Examples of the olefin to be polymerized include ethylene, propylene, butene-1, 3-methylbutene-1, 4-methylpentene-1, and the like.
-Olefins, especially propylene. The polymerization can be suitably applied to not only homopolymerization but also generally known random or block copolymerization. For example, when applied to block copolymerization, the balance between rigidity and impact resistance is improved, which is particularly preferable.

The ratio of each component of the catalyst used is such that the molar ratio of titanium in the catalyst component (A) to the metal of the component (B) to the electron donating compound of the component (C) is 1: 3 to 500: 0 to 100, preferably 1. : 20 to 200: 3 to 50
Chosen to be.

The polymerization reaction is carried out in the presence or absence of a solvent such as an inert hydrocarbon such as butane, pentane, hexane, heptane or toluene, or a liquefied α-olefin. The temperature is 40 to 100 ° C., preferably 50 to 90 ° C., and the pressure is not particularly limited, but is usually selected from the range of atmospheric pressure to 100 atm.

It is also possible to allow hydrogen to be present as a molecular weight regulator in the polymerization system.

In addition, means commonly employed for homopolymerization and copolymerization of an α-olefin can be applied to the present invention.

〔Example〕

Next, the present invention will be described more specifically by way of examples, but the present invention is not limited by these examples without departing from the gist thereof.

In the examples, the catalyst efficiency (shown as CE) is the amount of polymer produced (g) per 1 g of the solid catalyst component (A), and the polymerization activity (shown as K) is α-olefin pressure of 1 kg / hour. It is the polymer production amount (g) per 1 g of the solid catalyst component (A) per cm ² . The isotactic index (denoted as II) is the residual amount (% by weight) after extraction with boiling n-heptane for 6 hours in a modified Soxhlet extractor. Bulk density (shown as ρB. Unit is g / cc)
It was measured according to JIS-K-6721. Melt flow index (shown as MFI) was measured according to ASTM-D-1238.

The transparency was evaluated by the clarity of the scenery behind the film as seen through the 1 mm thick pressed film press-molded at 270 ° C., 50 cm away from the eyes. Here, the one that looks clear is marked with ◯, and the one that looks blurry is marked with ∆. The rigidity is the first yield strength YS (kg / cm ² ) and the flexural modulus (kg / cm ² ).
The first yield strength YS was determined by a tensile test of a dumbbell piece punched from a 1.0 mm-thick press sheet according to ASTM D638-72, and the flexural modulus was measured according to ASTM D-790-66.

Example 1 (A) Production of solid catalyst component In a 500 ml flask equipped with a stirrer and a thermometer, 5 g of commercially available Mg (OC ₂ H ₅ ) ₂ was collected under a purified N ₂ seal and Ti (OC ₄ H ₉ ) ₄ 7.4. g and tetraethoxysilane 4.6g were added, and the temperature was raised with stirring.
The reaction was carried out at 130 ° C for 1 hour. Thereafter, the temperature was lowered to 100 ° C., and a toluene solution of 8.2 g of phenol was added dropwise. After dropping, raise the temperature
The reaction was carried out at 130 ° C for 1 hour to obtain a slurry solid reaction product of a yellow solid.

After adding 87 ml of purified toluene thereto, the mixture was cooled to −20 ° C., and at −20 ° C., 25 g of TiCl ₄ was added. After the addition, the temperature was gradually raised, and after the temperature was raised to 80 ° C., 1.3 g of ethyl benzoate was added and the temperature was maintained for 1 hour. Thereafter, the solid was washed with purified toluene to obtain a solid product.

Next, 82 g of TiCl _{4 and} 1.3 g of ethyl benzoate were added, and the temperature was 80 ° C.
For 1 hour. Thereafter, the solid was washed four times with 200 ml of purified toluene at room temperature to obtain 4.8 g of a solid catalyst component (A). The Ti content in this solid was 2.8% by weight.

(B) Prepolymerization 0.58 mmol of triethylaluminum was added at room temperature under an argon seal to the induction stirring autoclave 1 thoroughly purged with purified argon, and 315 g of liquid 3-methylbutene-1 and 7 g of liquid propylene were charged. Then, the temperature was raised to 55 ° C., 1 g of the solid catalyst component (A) obtained in Example 1 (A) was added, and prepolymerization was carried out for 20 minutes. Then, it was washed three times with 200 ml of purified normal hexane at room temperature to obtain a prepolymerization catalyst component.

The prepolymerization catalyst component contained 30 g of the polymer per 1 g of the solid catalyst component (A).

(C) Polymerization of propylene To a 2 liter induction-stirring autoclave sufficiently replaced with purified argon, 1.0 mmol of triethylaluminum and 0.3 mmol of methyl paramethylbenzoate were added at room temperature under a blanket of argon, and H ₂ was added at 1.0 kg / cm ₃ at room temperature. ^In addition to ² , the liquid propylene 700g was charged. Next, the temperature was raised to 70 ° C., 15 mg of the prepolymerization catalyst component obtained in (B) above was added as a solid catalyst component (A), and polymerization was carried out at 70 ° C. for 1 hour.

After that, excess propylene was purged to obtain 290 g of powder polypropylene. The catalyst efficiency CE is 19,300 g-pp / g-Cat,
The polymerization activity K was 650. ΡB of the obtained polymer is 0.4
It was 7 g / cc, II was 97.2%, and MFI was 3.0. The transparency of this product was evaluated as ○, and the first yield strength YS was 380 kg /
cm ² , and the flexural modulus was 18,100 kg / cm ² . Various measurement results are summarized in Table-1.

Example 2 (B) Prepolymerization In (B) of Example 1, the amount of propylene charged was changed.
Prepolymerization was carried out in the same manner as in (B) of Example 1 except that the prepolymerization time was changed to 3 g and the prepolymerization time was changed to 40 minutes.

The obtained prepolymerization catalyst component contained 25 g of the polymer per 1 g of the solid catalyst component (A).

(C) Polymerization of propylene When propylene was polymerized in the same manner as in (C) of Example 1 except that the prepolymerization catalyst component obtained in Example 2 (B) was used, the catalyst efficiency CE = 18,000 g. −pp / g−Ca
t, polymerization activity K = 600, II = 97.0%, ρB = 0.46g / cc, MF
I = 3.4.

 The various measurement results are shown in Table 1.

Example 3 (B) Prepolymerization Prepolymerization was carried out in the same manner as in (B) of Example 1 except that the temperature and time of prepolymerization in Example 1 (B) were changed to 25 ° C. and 1 hour, respectively. I did. The obtained prepolymerization catalyst component contained 21 g of polymer per 1 g of solid catalyst component (A).

(C) Polymerization of Propylene Polymerization of propylene was carried out in the same manner as in (C) of Example 1 except that the prepolymerization catalyst component obtained in Example 3 (B) was used, and the catalyst efficiency CE = 17,400 g. −pp / g−Ca
t, polymerization activity K = 580, II = 97.0%, ρB = 0.46g / cc, MF
I was 3.2.

 The various measurement results are shown in Table 1.

Example 4 (B) Prepolymerization Prepolymerization was carried out in the same manner as in (B) of Example 1 except that the prepolymerization time was changed to 3 minutes in (B) of Example 1. The obtained prepolymerization catalyst component was 1 g of solid catalyst component (A).
It contained 5 g of polymer per unit.

(C) Polymerization of propylene When propylene was polymerized in the same manner as in (C) of Example 1 except that the prepolymerization catalyst component obtained in Example 4 (B) was used, the catalyst efficiency CE = 16,200 g- pp / g-Cat, polymerization activity K = 540, II = 96.8%, ρB = 0.45 g / cc, MFI = 4.
Was 2.

 The various measurement results are shown in Table 1.

Example 5 In (B) of Example 1, 3
Prepolymerization was carried out in the same manner as in (B) of Example 1 except that only methylbutene-1 was used and the prepolymerization time was 1 hour. The obtained prepolymerization catalyst component was 1 g of solid catalyst component (A).
It contained 20 g of polymer per unit.

(C) Polymerization of propylene When propylene was polymerized in the same manner as in (C) of Example 1 except that the prepolymerization catalyst component obtained in Example 5 (B) was used, the catalyst efficiency CE = 12,600 g- pp / g-Cat, polymerization activity K = 420, II = 96.5%, ρB = 0.46g / cc, MFI = 3.
Was eight.

 The various measurement results are shown in Table 1.

Example 6 (A) Production of solid catalyst component In the same manner as in Example 1, 4.8 g of commercially available MgCl ₂ was collected, and 25 ml of purified normal decane and 2-ethylhexanol 2 were collected.
3.5 ml was added, the temperature was raised with stirring and the reaction was carried out at 130 ° C. for 2 hours. Thereafter, 1.1 g of phthalic anhydride was added at the same temperature, and after the addition, the mixture was reacted at 130 ° C. for 1 hour to obtain a uniform solution.

I had Thereafter, the solid was washed with purified toluene to obtain a solid product.

This solution was added dropwise to 345 g of TiCl ₄ cooled to −20 ° C. over 1 hour. After the dropping, the temperature was gradually raised, and after 4 hours, the temperature was raised to 110 ° C. Diisobutyl phthalate at 110 ℃
2.8 g was added and reacted at the same temperature for 2 hours.

Then, this was hot-filtered to collect the solid part, and TiCl ₄ 3
After suspending in 45 g, the temperature was raised to 110 ° C and the reaction was carried out at 110 ° C for 2 hours. Thereafter, the product was washed twice with 200 ml of hot normal decane and further washed 5 times with 200 ml of purified normal hexane at room temperature to obtain 3.5 g of the solid catalyst component (A).

 The Ti content of this product was 3.2% by weight.

(B) Prepolymerization Using the solid catalyst component obtained in Example 6 (A), prepolymerization was carried out in the same manner as in Example 1 (B) to obtain a prepolymerized catalyst component. This prepolymerization catalyst component is 1 g of solid catalyst component (A)
It contained 20 g of polymer.

(C) Polymerization of Propylene In Example 1 (C), the prepolymerization catalyst component obtained in Example 6 (B) was used, and 0.05 mmol of phenyltriethoxysilane was used instead of methyl paramethylbenzoate. Polymerization of propylene was carried out in the same manner as in Example 1 (C) except that the powder was used and H ₂ was changed to 0.3 kg / cm ² to obtain 230 g of powder polypropylene. Catalytic efficiency CE is 15,300g-p
p / g-Cat, polymerization activity K is 510, ρB is 0.45 g / cc, I
I was 97.5% and MFI was 10.5. The transparency of this product was evaluated as ◯, the first yield strength YS was 372 kg / cm ² , and the flexural modulus was 17,200 kg / cm ² .

Comparative Example 1 (B) Prepolymerization 18 ml of normal hexane at room temperature under N ₂ seal in an induction-stirring type glass autoclave 1 fully substituted with purified N ₂ .
1.2 mmol of triethylaluminum was added, and the solid catalyst component (A) obtained in (A) of Example 1 was further added at room temperature.
1 g was added. Then, the temperature was maintained at 25 ° C., and propylene gas was passed for 3 minutes to carry out prepolymerization. After the completion of the prepolymerization, 120 ml of normal hexane was added, and the whole amount was transferred to a 200 ml flask sufficiently replaced with purified N ₂ and used for the main polymerization. The prepolymerization catalyst component thus obtained contained 10 g of polypropylene per 1 g of the solid catalyst component (A).

(C) Polymerization of propylene When propylene was polymerized in the same manner as in (C) of Example 1 except that the prepolymerization catalyst component obtained in Comparative Example 1 (B) was used, the catalyst efficiency CE = 19,800 g- pp / g-Cat, polymerization activity K = 660, II = 97.2%, ρB = 0.47 g / cc MFI = 4.2
Met.

 The various measurement results are shown in Table 1.

The transparency of this product is evaluated as △ because it looks fuzzy, the first yield strength YS is 330 kg / cm ² , and the flexural modulus is 1.
It was 5,100 kg / cm ² .

From the above results, 3-methylbutene-1 or 3-
It was revealed that a polymer having excellent transparency and rigidity can be obtained by the main polymerization using a prepolymerization catalyst component prepolymerized with a mixture of methylbutene-1 and propylene.

[Effects of the Invention] According to the method of the present invention, not only a propylene polymer having excellent transparency and rigidity and a high bulk density can be obtained, but also the polymerization activity and stereoregularity are high, so that a catalyst residue after polymerization or The step of removing the amorphous polymer is unnecessary, which is industrially advantageous.

[Brief description of drawings]

FIG. 1 is a flow chart for facilitating the understanding of the technical content of the present invention regarding a Ziegler catalyst.

Claims (7)

[Claims] 1. A solid catalyst component (A) containing magnesium, titanium, halogen and an electron-donating compound as essential components and a compound (B) represented by the general formula AlR ⁵ _j X _3-j (wherein R ⁵ Is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen, and j is 2
In the presence of a catalyst consisting of
3-methylbutene-1, or 3-methylbutene-1
And a olefin having 3 or more carbon atoms are prepolymerized to obtain a prepolymerized component, and then, the olefin having 3 or more carbon atoms is homopolymerized or copolymerized in the presence of the prepolymerized component and, if necessary, an additional compound (B). A method for producing an olefin polymer, comprising: 2. A process according to claim 1, characterized in that a mixture of 3-methylbutene-1 and propylene is prepolymerized. 3. The method according to claim 1, wherein the electron donating compound (C) is present together with the compound (B). 4. A process according to claim 1, characterized in that the prepolymerization temperature is above 50.degree. 5. The method according to claim 1, wherein the amount of polymerization in the prepolymerization is 0.01 to 100 g per 1 g of the solid catalyst component (A). 6. The method according to claim 1, wherein the polymerization amount of the prepolymerization is 0.001 to 30% by weight based on the total polymerization amount. 7. The solid catalyst component (A) has the general formula Mg (OR ¹ ) _2-n
A magnesium compound represented by X _n (wherein R ¹ represents an alkyl group, an aryl group or an aralkyl group, X is a halogen, and n is 0 ≦ n ≦ 2), a general formula Ti (OR ² ) _m X _4-m (wherein R ² represents an alkyl group, an aryl group or an aralkyl group, X represents a halogen, and m represents 0 ≦ m ≦ 4), and a titanium compound and an electron donating compound are reacted. A method according to claim 1, characterized in that it is obtained.