JPH06104690B2 - Process for producing catalyst component for α-olefin polymerization - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a catalyst component for α-olefin polymerization. More specifically, the present invention relates to a method for producing a so-called carrier-type titanium-containing solid catalyst component having a high degree of stereoregular polymerization ability and activity for producing an α-olefin polymer having stereoregularity. The carrier-type titanium-containing solid catalyst component according to the present invention is further used in combination with an organoaluminum compound as a catalyst for polymerization of α-olefin.

Prior Art Regarding titanium-supported catalyst systems, it has long been known to add various electron-donating compounds to the catalyst system for the purpose of improving the stereoregularity of the polymer (J. Poly
mer Science, Polymer Letters, 3,855 (1965), in particular, many catalyst production methods have been proposed in which an electron-donating compound is contained in a titanium-supported solid catalyst component. Among electron-donating compounds such as esters, amines, ketones, and ethers, esters, particularly esters of polycarboxylic acids having a specific structure and esters of monocarboxylic acids having an alkyl group of a specific structure, are stereoregular. It has been shown to exert an excellent effect in obtaining a functional polymer (JP-A-54)
-94590, JP-A-57-63310, JP-A-57-63311,
And JP-A-58-145707.

It is also known that the performance of the catalyst is improved by combining these electron-donating compounds with a halogenating agent such as an interhalogen compound, a halogen or a metal halogen compound (JP-A-54-54). 3894, 54-31092).

SUMMARY OF THE INVENTION The present inventors previously disclosed in JP-A-60-130607,
It was clarified that an excellent solid catalyst component for α-olefin polymerization can be produced by using an electron-donating compound having a specific structure. The present inventors combined the same electron-donating compound and interhalogen compound or halogen used in the above-mentioned prior application to obtain the electron-donating compound and interhalogen compound or halogen shown in the above-mentioned known art. The present invention has been completed by finding that a titanium-containing solid catalyst component for stereoregular polymerization of α-olefin is obtained, which is superior to the combination thereof.

That is, the present invention comprises: Component (A): magnesium halide-containing solid, Component (B): (Where R is a C _1-12 hydrocarbon residue or A C _2-12 organic residue having a structural site represented by, R ¹ and R ² are each a C _1-12 alkyl group, aryl group, alkyl-substituted aryl group, or aryl-substituted alkyl group), Component (C): a tetravalent titanium halogen compound, and component (D): an interhalogen compound and / or halogen are brought into contact with each other to provide a process for producing a catalyst component for α-olefin polymerization. Is.

Effects of the Invention It is well known to use organic carboxylic acid monoesters as electron donating compounds to be incorporated into the solid titanium catalyst component, especially in the stereoregular polymerization of α-olefins with organoaluminum compounds and Si-O-. When a Ziegler-type catalyst is formed by combining a co-catalyst composed of a silicon compound having a C bond and a solid titanium catalyst component, the organic carboxylic acid monoester contained in the solid titanium catalyst component is an aromatic carboxylic acid ester (special (Kaisho 54-94590) and It is known that (at least one of R and R'is a saturated or unsaturated branched chain hydrocarbon residue having 3 to 20 carbon atoms) (JP-A-57-63310). is there.

When the compounds defined by the component (B) of the present invention are used in place of these known electron-donating compounds, a higher degree of α-olefin stereoregular polymerization can be achieved owing to the effect thereof alone ( JP-A-60-130607).

In the method of the present invention, titanium obtained by the method of the above-mentioned prior application by bringing the component (A), the component (B), the component (C) and the interhalogen compound and / or the halogen [component (D)] into contact with each other. It is possible to produce a titanium-containing catalyst component having an activity and stereoregular polymerization performance superior to those of the solid catalyst component.

DETAILED DESCRIPTION OF THE INVENTION The titanium-containing solid catalyst component of the present invention is produced by bringing the component (A), the component (B), the component (C) and the component (D) into contact with each other.

[Component (A)]

Component (A) is a magnesium halide-containing solid. As the halogen, fluorine, chlorine, bromine and iodine can be used, of which chlorine is preferable.

Here, the "magnesium halide-containing solid" means magnesium halide itself, magnesium halide modified by another electron donating compound other than the component (B), or a magnesium halide dissolving agent ( For example, a solid compound such as a solid product obtained by subjecting a hydrocarbon solution containing tetrabutyl titanate, an ether, a phosphoric acid ester) to a precipitation treatment by a known method (eg, addition of methylhydrogenpolysiloxane, titanium tetrachloride). It also includes.

[Component (B)]

The component (B) is an electron donating compound represented by the following formula.

Here, R is a hydrocarbon residue having 1 to 12 carbon atoms (C _1-12 ),
Or It is an organic residue having a structural part and having 2 to 12 carbon atoms (C _2-12 ). R is preferably a relatively short-chain unbranched hydrocarbon residue having 1 to 4 carbon atoms, and The carbons of are preferably unbranched carbon atoms. In addition, as this compound, a compound having no polar atom such as O, S and N in a portion other than the above-mentioned specific structure is generally used. R ¹ and R ² are each 1 to 1 carbon atoms
12 represents an alkyl group, an aryl group, an alkyl-substituted aryl group, or an aryl-substituted alkyl group. Among the compounds represented by the formula (B), particularly preferred are ethylene oxide or propylene oxide of a lower aliphatic monocarboxylic acid (R ¹ has about 1 to 12 carbon atoms) or benzoic acid (R ¹ is a phenyl group). Ethers of adducts (1 mol), especially lower (C _1-12 ) alkyl or phenyl or tolyl ethers.

Specific examples of such an electron donating compound include, for example, 2-methoxyethyl acetate (CH ₃ CO ₂ CH ₂ CH ₂
OCH ₃ ), 2-ethoxyethyl acetate (CH ₃ CO ₂ CH ₂ C
H ₂ OC ₂ H ₅ ), 2-butoxyethyl acetate (CH ₃ CO ₂ C
H ₂ CH ₂ OC ₄ H ₉ ), 3-methoxybutyl acetate (CH ₃ C
O ₂ (CH ₂ ) ₂ CH (OCH ₃ ) CH ₃ ), 2- (2-ethoxyethoxy) ethyl acetate (CH ₃ CO ₂ CH ₂ CH ₂ OCH ₂ CH ₂ OC
₂ H ₅ ), 2-p-triloxyethyl acetate (CH ₃ CO
₂ CH ₂ CH ₂ OC ₆ H ₄ (CH ₃ )), ethoxylmethyl acetate (CH ₃ CO ₂ CH ₂ OC ₂ H ₅ ), 3-ethoxypropyl acetate (CH ₃ CO ₃ CH ₂ CH ₂ CH ₂ OC) ₂ H ₅ ), 4-ethoxybutyl acetate (CH ₃ CO ₂ CH ₂ CH ₂ CH ₂ CH ₂ OC ₂ H ₅ ), n-butylcarbitol acetate (CH ₃ CO ₂ (CH ₂ CH ₂ O) ₂ C ₄ H ₉ ), 2
- butoxyethyl = propionate _{(CH 3 CH 2 CO 2 CH} 2 CH 2 O
C ₄ H ₉ ), 2-isobutoxyethyl propionate (CH
₃ CH ₂ CO ₂ CH ₂ CH ₂ OCH ₂ CH (CH ₃ ) ₂ ), 2-ethoxyethyl =
n- butyrate _{(C 4 H 9 CO 2 CH} 2 CH 2 OC 2 H 5), 2- ethoxyethyl = isobutyrate _{((CH 3) 2 CHCO 2} CH 2 CH 2 OC
₂ H ₅ ), 2-ethoxyethyl benzoate (C ₆ H ₅ CO ₂ CH
_{2 CH 2 OC 2 H 5)} , 2- isopropoxyethyl = benzoate _{(C 6 H 5 CO 2 CH} 2 CH 2 OCH (CH 3) 2), p- methoxybenzyl = acetate (CH ₃ CO ₂ CH ₂ -C ₆ H ₄ OCH ₃ ), 4′-ethoxyphenyl = 4-n-butylbenzoate (CH ₃ (CH ₂ ) ₃ C
_{6 H 4 CO 2 C 6 H} 4 OC 2 H 4), tetrahydrofurfuryl = n-butyrate _{(CH 3 (CH 2) 2} CO 2 CH 2 (C 4 H 7 O)) and the like. Of these, 2-ethoxyethyl acetate and 2-
Methoxyethyl acetate is preferred.

[Component (C)]

 The component (C) is a halogen compound of tetravalent titanium.

Chlorine is preferred as the halogen. A preferred titanium halogen compound has the general formula Ti (OR ') _n Cl _4-n (R' is C ₁ -C ₆
Of the hydrocarbon residues), n = 0 or 1. Specific examples thereof include titanium tetrachloride and titanium trichlorobutoxy.

[Component (D)]

The component (D) is an interhalogen compound and a halogen, and is defined by the general formula XY _n . (X = Y
In the case of X ₂ and XY, n = 1, 3, 5 or 7, X and Y are halogens).

Specifically, ClF, BrF, IF, BrCl, ICl, IBr, ClF ₃ , Br
F ₃ , IF ₃ , ICl ₃ (or I ₂ Cl ₆ ), ClF ₅ , BrF ₅ , IF ₅ , I
_{F 7 ,, Cl 2, Br 2} , and the like I _2. Of these interhalogen compounds or halogens, ICl, ICl ₃ , I ₂ , Cl ₂
Is preferred, and ICl and / or ICl ₃ is particularly preferred. It is also possible to use two or more of these in admixture.

[Quantity ratio]

The component ratios of the four components (A) to (D) are arbitrary and not critical as long as the effects of the present invention are recognized.

Generally, the component (B) has a molar ratio [component (B) / Mg] of the electron-donating compound component (B) to the magnesium halogen compound present in the component (A) of 0.001 to 6, preferably 0.001. Used at a rate of ~ 0.6.

Component (C) can be used in a wide range of proportions, but generally the amount of titanium atoms contained in the titanium-containing solid catalyst component produced by various methods is in the range of 0.5 to 15% by weight, preferably 0.5 to 10% by weight. It is preferable to adjust it to be within.

The component (D) can also be used in a wide range, but generally, the molar ratio of the component (D) to the magnesium halogen compound in the component (A) [component (D) / Mg] is 0.001 to 10, preferably 0.005. Used in the range of ~ 2.

[Preparation of titanium-containing solid catalyst component]

The titanium-containing solid catalyst component of the present invention comprises the constituent component (A),
It can be obtained by contacting the component (B), the component (C) and the component (D) all at once or stepwise or once or a plurality of times. The contact order and contact method of the four components are arbitrary. Some of the specific preparation methods are shown below.

i) MgX ₂ (magnesium halide) and component (B) are mixed and pulverized, and the obtained pulverized product is brought into contact with the mixture of component (C) and component (D) in a liquid phase.

ii) Component (A), component (B) and component (C) are mixed and pulverized, and the obtained pulverized product and component (D) are brought into contact with each other in a liquid phase in an inert solvent.

iii) MgX ₂ (magnesium halide) as alcohol,
A hydrocarbon solution containing MgX ₂ was prepared using a dissolving agent such as ether, alkoxide of titanium, or trialkyl phosphate, and the solution was brought into contact with a halogenating agent of titanium or silicon to precipitate a solid (a component (A ))), The precipitated solid is contacted with the component (B), the component (C) and the component (D) simultaneously or sequentially.

iv) Component (B) is added to the hydrocarbon solution containing MgX ₂ obtained in the method of iii), and this solution is contacted with a halogenating agent to precipitate a solid (component (A) and component (B)).
Contacted product), the precipitated solid and the component (C) are contacted in a liquid phase, and further contact-treated with a mixture of the component (C) and the component (D).

v) MgX ₂ is dissolved in a hydrocarbon solvent using butyl titanate, reacted with methylhydrogenpolysiloxane to precipitate a solid, and the precipitated solid containing MgX ₂ is brought into contact with the component (B), and further the component (B) is added. C) and component (D) are contacted sequentially or simultaneously or a plurality of times.

The feature of the present invention is that the electron-donating compound having a specific molecular structure, the interhalogen compound and / or the halogen are necessarily used in the production process of the titanium-containing solid catalyst component. As long as it is, the effect is exhibited even in the other various methods for preparing a titanium-containing solid catalyst component. Therefore, the method for producing the titanium-containing solid catalyst component of the present invention is not limited to the method exemplified above.

[Polymerization of α-olefin]

The titanium-containing solid catalyst component of the present invention can be used for the polymerization of α-olefin by combining it with an organoaluminum compound.

The organoaluminum compound has the general formula AlR _n X _3-n (however,
R is a hydrocarbon residue having 1 to 12 carbon atoms, X is a halogen, and n is 0 <n ≦ 3).

Specific examples of such an organoaluminum compound include triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, triisohexylaluminum, trioctylaluminum. , Diethyl aluminum hydride, diisobutyl aluminum hydride, diethyl aluminum monochloride, ethyl aluminum sesquichloride and the like. Of course, these aluminum compounds
It is also possible to use together more than one species.

Among these, trialkylaluminum is preferable,
Triethylaluminum is particularly preferable.

When carrying out a polymerization reaction of α-olefin having 3 or more carbon atoms, a catalyst system comprising a titanium-containing solid catalyst component and an organoaluminum compound according to the present invention is used for the purpose of improving stereoregularity of a produced polymer. Up to this, many compounds which have been proposed for use in Ziegler polymerization catalysts and which have an effect on stereoregularity can be further added. Examples of the compound used for such a purpose include aromatic monocarboxylic acid esters, Examples thereof include an organosilicon compound having a bond and a nitrogen or oxygen heterocyclic compound having an alkyl substituent. Specifically, for example, ethyl benzoate, ethyl p-toluate, ethyl p-anisate, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, t-
Butylmethyldimethoxysilane, tetraethylsilicate, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethylpyran and the like.

The use ratio of the titanium-containing solid catalyst component and the organoaluminum compound can be varied over a wide range, but in general, it is 1 to 1000, preferably 10 to 500 (molar ratio) per titanium atom contained in the solid catalyst component. Organoaluminum compounds can be used.

The amount of the above-mentioned stereoregulation improver used for the purpose of improving the stereoregularity of the α-olefin polymer can be achieved even when the titanium-containing solid catalyst component of the present invention is used in a very small amount. However, it is usually used in a proportion of 0.001 to 1 mol, preferably 0.01 to 0.5 mol, per 1 mol of the organoaluminum compound.

The contact or mixing order and number of times of the titanium-containing solid catalyst component, the organoaluminum compound and the steric regulation improving agent are arbitrary.

Further, the titanium-containing solid catalyst component according to the present invention can be subjected to a preliminary contact treatment (so-called preliminary polymerization treatment) with a small amount of olefin in the presence of an organoaluminum compound prior to the polymerization of α-olefin. The olefins that can be used in the prepolymerization treatment may be the same α-olefin used in the polymerization or different α-olefins.

The olefins used for the polymerization include ethylene, propylene, 1-butene, 1-hexene, 4-methylpentene-
1, etc., and not only homopolymerization but also random copolymerization and block copolymerization of these can be performed. Regarding copolymerization, polyunsaturated compounds such as conjugated dienes and non-conjugated dienes can also be used as the copolymerization olefin.

As the polymerization method, a so-called slurry polymerization method in which an inert hydrocarbon such as hexane or heptane is used as a solvent, a liquid phase polymerization method in which a liquefied monomer is used as a solvent, or a gas phase polymerization method in which a monomer is present as a gas phase can be used. .

The polymerization temperature is generally about 20 to 150 ° C, preferably 40 to 100 ° C.
The polymerization pressure is about atmospheric pressure to about 100 atmospheres, preferably about atmospheric pressure to about 50 atmospheres. The molecular weight of the polymer is controlled mainly by a method using hydrogen.

Experimental Example Example 1 (Production of Titanium-Containing Solid Catalyst Component) 50 ml of dehydrated and deoxygenated n-heptane was introduced into a 300 ml flask which had been sufficiently purged with nitrogen, and then 0.1 mol of MgCl ₂ (magnesium chloride) and Ti (OBu). ) ₄ (Tetrabutoxytitanium) was introduced in an amount of 0.2 mol and reacted at 90 ° C. for 2 hours to prepare a hydrocarbon solution of MgCl ₂ . Then add 12 ml of methylhydrogen polysiloxane (20 cps) and add 4
When reacted at 0 ° C. for 3 hours, about 40 g of an off-white solid was deposited. When this precipitated solid was thoroughly washed with n-heptane and analyzed, it was found that the precipitated solid contained 12.1% by weight of MgCl ₂
Was included.

20 g (MgCl ₂ = 2.42 g) was sampled from this precipitated solid, diluted with 80 ml of n-heptane, and 0.37 ml of 2-ethoxyethyl acetate (CH ₃ CO ₂ CH ₂ CH ₂ OC ₂ H ₅ /Mg=0.11 mol) was added. Ratio) and diluted with 50 ml of n-heptane TiCl ₄ 1.0 ml
Is added and reacted at room temperature for 1 hour. After the reaction is complete, the product is washed with n-heptane. Next, 1.7 ml of TiCl ₄ is added and reacted at 50 ° C. for 1 hour. The product is washed with n-heptane. Next, 25 ml of TiCl ₄ is added and reacted at 70 ° C. for 1 hour. The product is washed with n-heptane to obtain a titanium-containing solid component.

To the obtained titanium-containing solid component, 0.1 g of ICl ₃ and 50 ml of 1,2-dichloroethane are dissolved and added, and the mixture is heated at 80 ° C. for 1 hour. After standing still and removing the supernatant, 25 ml of TiCl ₄ is added and reacted at 80 ° C. for 2 hours. After leaving it to stand and removing the supernatant, TiCl ₄
Is added to the mixture and treated at 80 ° C for 2 hours. After completion of the reaction, the solid was washed with decantation (n-heptane 200 m
l times 5 times) to obtain the target titanium-containing solid catalyst slurry. When a part of this slurry was sampled and n-heptane was evaporated to dryness and analyzed, it was found that 3.09% by weight of titanium was contained in the solid.

(Polymerization of Propylene) (a) Polymerization-1 An autoclave equipped with a stirrer having an internal volume of 1 liter was used, and 500 ml of dried and degassed n-heptane, 107 mg of diphenyldimethoxysilane and 250 of triethylaluminum.
0.5 mg (Si / Al = 0.2 mol ratio) and 0.5 mg in terms of Ti atom from the above titanium-containing solid catalyst component slurry were introduced in this order under a propylene atmosphere, and 150 ml of hydrogen was added to initiate polymerization. Polymerization is carried out at a propylene pressure of 7 kg / cm ² G, 70 ° C / 3
It was done under the condition of time. After the completion of the polymerization, residual monomers were purged, the polymer slurry was separated, and the amount of each polymer produced was determined by drying the powder polymer and concentrating the liquid.

Stereoregularity of this powder polymer (hereinafter referred to as product II)
Was determined by a boiling n-heptane extraction test. Also, all
II (ratio of boiling n-heptane-insoluble polymer amount to total produced polymer amount) is total II = powder polymer amount x product II
It was determined by the relational expression: / (amount of powder polymer + amount of liquid concentrated polymer). These results are shown in Table-1.

(B) Polymerization-2 For polymerization-2, propylene polymerization conditions are 7 kg / cm ² G, 70 ° C / 8
It was carried out under exactly the same conditions as Polymerization-1 except that the time was changed to 0.3 mg of the titanium-containing solid catalyst component slurry in terms of Ti atom. These results are shown in Table-1.

(C) Polymerization-3 Polymerization-3 is te instead of diphenyldimethoxysilane.
rt-Butylmethyldimethoxysilane 72.8 mg (Si / Al = 0.2
Polymerization-1 was carried out under exactly the same conditions except for the molar ratio). These results are shown in Table-1.

Example 2 A titanium-containing solid component obtained by the same method as in Example 1 was added.
The procedure of contact treatment with 25 ml of TiCl ₄ at 80 ° C. for 2 hours was repeated twice, the supernatant was removed, and the solid was washed with heptane by decantation, and then 50 ml of 1,2-dichloroethane.
And ICl 0.4 g were added, and contact treatment with the component (D) was performed under the condition of 75 ° C. for 1 hour. After completion of the reaction, the solid was washed by decantation to obtain the target titanium-containing solid catalyst component slurry. (Ti content 3.44% by weight) Using the obtained titanium-containing solid catalyst component, propylene was polymerized by the method of Polymerization-1 in Example 1. The results are shown below.

Activity: 32.8 × 10 ⁴ (gpp / gTi) 11,300 (gpp / g solid catalyst) Attack production rate: 0.73% Product II: 97.8% Total II: 96.9% MFR: 4.2 BD: 0.45 Examples 3 to 6 Titanium-containing solid catalyst In the production of the components, the titanium-containing solid catalyst was prepared under the same conditions and method as in Example 1, except that the type and treatment amount of the interhalogen compound or halogen defined in component (D) were changed as shown in Table 2. The ingredients were manufactured.

Polymerization of propylene was carried out in the same manner as Polymerization-1 of Example 1 except that each of the titanium-containing solid catalyst components obtained above was used. The results are shown in Table-2.

Example 7 In producing the titanium-containing solid catalyst component, 0.1 g of ICl and 25 ml of TiCl ₄ were added to the titanium-containing solid component obtained in Example 1 and the mixture was treated at 80 ° C. for 2 hours. After removing the supernatant, TiCl
KoTsuta 2 hours at 80 ° C. by the addition of ₄ 25 ml. After completion of the reaction, the solid was washed by decantation (200 ml of n-heptane 5 times) to obtain a target titanium-containing solid catalyst component slurry.

Polymerization of propylene was carried out under the conditions of Polymerization-1. The results are also shown in Table-2.

Comparative Example 1 In the production of a titanium-containing solid catalyst component, the same condition and method as in Example 2 were used without using the metal halide compound of Group VB and / or VIB of the periodic table defined by the component (D). A solid catalyst component was produced.

Polymerization of propylene was carried out in the same manner as Polymerization-1 except that the obtained solid catalyst component was used. The results are also shown in the table −
Note in 3.

Comparative Example 2 In the production of a titanium-containing solid catalyst component, 0.40 ml of known ethylbenzoate (C ₆ H ₅ CO ₂ C ₂ H ₅ /Mg=0.11 mol) was used instead of the electron-donating compound defined as the component (B). A solid catalyst component was manufactured under the same conditions and method as in Comparative Example 1 except that the ratio was added.

Polymerization of propylene was carried out in the same manner as Polymerization-1 except that the obtained solid catalyst component was used. The results are shown in Table-3.

Comparative Example 3 In the production of a titanium-containing solid catalyst component, 0.40 ml of known ethylbenzoate (C ₆ H ₅ CO ₂ C ₂ H ₅ /Mg=0.11 mol) was used instead of the electron-donating compound defined as the component (B). A solid catalyst component was produced under the same conditions and method as in Example 2 except that the ratio was added.

Polymerization of propylene was carried out in the same manner as Polymerization-1 except that the obtained solid catalyst component was used. The results are shown in Table-3.

Example 8 (Production of Titanium-Containing Solid Catalyst Component and Preliminary Polymerization Treatment Catalyst Thereof) A titanium-containing solid catalyst component was produced according to the method and conditions of Example 1 and prepolymerization treatment was carried out. In the pre-polymerization treatment, a heptane slurry was prepared using 3 g of titanium-containing solid catalyst component (titanium content 3.09% by weight) (30 g solid catalyst / l slurry), and 0.44 g of triethylaluminum (Al /
After Ti (molar ratio) = 2) was added, 6 g of propylene was introduced and contacted for 20 minutes.

Using the obtained prepolymerized catalyst of the present invention, propylene polymerization was carried out in the same manner as Polymerization-1 of Reference Example 1 by introducing each catalyst component under the temperature condition of 70 ° C.

The results obtained are shown below.

Activity: 38.8 × 10 ⁴ (gpp / gTi) 12,000 (gpp / g solid catalyst) Attack production rate: 0.45 (%) Product II: 98.9 (%) Total II: 98.5 (%) MFR: 1.4 (g / 10 min) BD: 0.47 (g / cc)

[Brief description of drawings]

FIG. 1 is intended to help the understanding of the technical content of the present invention regarding the Ziegler catalyst.

Claims (1)

[Claims] 1. Component (A): magnesium halide-containing solid, component (B): (Where R is a C _1-12 hydrocarbon residue or A C _2-12 organic residue having a structural site represented by, R ¹ and R ² are each a C _1-12 alkyl group, aryl group, alkyl-substituted aryl group, or aryl-substituted alkyl group), Component (C): a tetravalent titanium halogen compound, and component (D): an interhalogen compound and / or halogen are brought into contact with each other, and a method for producing a catalyst component for α-olefin polymerization.