JPH0791335B2 - Method for producing polypropylene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing polypropylene. More specifically, it relates to a method for producing a high-rigidity polypropylene having extremely excellent transparency.

[Conventional technology and its problems]

The Applicant has previously proposed a method for producing a high-rigidity polypropylene using a catalyst obtained by combining a titanium trichloride composition obtained by a specific method with a specific usage ratio of an organoaluminum compound and a specific organosilicon compound. (Japanese Patent Application No. 63-121,523, Japanese Patent Application Nos. 63-123,673 and 63-1
36,821, hereinafter referred to as prior invention. According to the method of the invention of the prior application, it has become possible to produce polypropylene capable of obtaining a molded article having extremely high rigidity without adding any special additive.

However, although the polypropylene obtained by the method of the invention of the prior application has high rigidity as described above, it is semi-transparent, so the commercial value may be impaired in the field of use, and improvement in transparency is desired. It was rare.

On the other hand, as an attempt to improve the transparency of polypropylene and another attempt to improve the rigidity, a 3-
Multi-stage polymerization method in which a small amount of methylbutene-1,4,4-dimethylhexene-1,4,4-dimethylpentene-1 and allyltrimethylsilane is polymerized (JP-B-45-32,430, JP-A-62-275,109) JP-A-63-15,804 and JP-A-63-218,709) have been proposed. When the present inventors produced polypropylene according to the proposed method, propylene was obtained by any method. Not only the polymerization activity of is decreased, but also a lumpy polymer is generated,
It was a method that cannot be used in the industrial long-term continuous polymerization method. Further, the rigidity of the obtained polypropylene was lower than that of the polypropylene obtained by the method of the prior invention, which was insufficient. Further, when the polypropylene was processed into a film, a certain improvement in transparency was observed, but many voids were generated in the film, which impaired the commercial value.

As a similar technique, a method of polymerizing propylene using a catalyst component obtained by adding a polymer such as 3-methylbutene-1 during the production of a transition metal catalyst component for propylene polymerization (JP-A-63- 69,809 publication) has been proposed,
Since the proposed method requires a separate step for producing a polymer such as 3-methylbutene-1, it is not only industrially disadvantageous, but also has insufficient rigidity similar to that of the above-mentioned multistage polymerization technique,
There was a problem of void generation in the film.

The present inventors diligently studied a method for producing a high-rigidity polypropylene with improved transparency, which solves the problems of the prior invention and the prior art described above. As a result, a polypropylene is produced by a catalyst prepared by combining a titanium trichloride composition containing a specific branched chain olefin polymer and an organoaluminum compound by a specific method, and a specific amount of a specific organosilicon compound. In the case of, in addition to the polypropylene obtained by the method of the invention of the prior application to solve the problems in manufacturing and quality of the above-mentioned conventional technology, not only is it extremely transparent, but also in rigidity. I found that
The present invention has been completed.

As is clear from the above description, an object of the present invention is to provide a method for producing a high-rigidity polypropylene having extremely few voids and having extremely excellent transparency. Another object is to provide a high-rigidity polypropylene having remarkably excellent transparency and having extremely few voids.

[Means for Solving the Problems]

 The present invention has the following configurations.

(1) A solid product (II) obtained by reacting an organoaluminum compound (A ₁ ) or a reaction product (I) of an organoaluminum compound (A ₁ ) and an electron donor (B ₁ ) with titanium tetrachloride. ) Is (In the formula, R ¹ represents a silicon-containing chain hydrocarbon group having 1 to 3 carbon atoms, or silicon, and R ² , R ³ , and R ⁴ represent 1 to 3 carbon atoms which may contain silicon. 6 represents a chain hydrocarbon group up to 6, but any one of R ² , R ³ and R ⁴ may be hydrogen), and is polymerized with a branched olefin group represented by A titanium trichloride composition (III) obtained by the method of reacting (B ₂ ) with a halide of an element of Group III to VI of the periodic table, comprising the following formula: (In the formula, R ¹ represents a silicon-containing chain hydrocarbon group having 1 to 3 carbon atoms, or silicon, and R ² , R ³ , and R ⁴ represent 1 to 3 carbon atoms which may contain silicon. A branched chain olefin polymer having a repeating unit of up to 6 in which any one of R ² , R ³ and R ⁴ may be hydrogen. % To 99% by weight of a titanium trichloride composition (III), an organoaluminum compound (A ₂ ) and an organosilicon compound (S) having a Si—O—C bond and / or a mercapto group are combined to obtain the organosilicon compound. The molar ratio (S) / (III) of the compound (S) to the titanium trichloride composition (III) is 1.0 to 10.0, and the mole of the organoaluminum compound (A ₂ ) to the titanium trichloride composition (III). the ratio of using the _{(a 2) / (III)} = 0.1~200 and catalyst to polymerize propylene Method for producing a polypropylene, characterized in that.

(2) The general formula of the organoaluminum compound (A ₁ ) is
AlR ⁵ _p R ⁶ _{p ′} X _{3- (p + p ′)} (In the formula, R ⁵ and R ⁶ represent a hydrocarbon group such as an alkyl group, a cycloalkyl group, an aryl group or an alkoxy group, and X represents a halogen; p,
p'represents an arbitrary number of 0 <p + p'≤3. ) The method according to the item (1), wherein an organoaluminum compound represented by the formula (1) is used.

(3) The method according to (1) above, wherein a dialkylaluminum monohalide is used as the organoaluminum compound (A ₂ ).

(4) In place of the titanium trichloride composition (III), the titanium trichloride composition (III) is combined with an organoaluminum compound, and the catalyst component pre-activated with a small amount of α-olefin is used. The method according to item 1).

(5) Polypropylene melt flow rate (MFR) Absorbance ratio by infrared absorption spectroscopy (IR-τ: Absorbance ratio at infrared wave number 997 cm ^-1 and 973 cm ^-1 , A ₉₉₇ /
The method according to the above (1), wherein the relationship with A ₉₇₃ ) satisfies the formula IR−τ ≧ 0.0203 log MFR + 0.950.

The titanium trichloride composition (III) used in the present invention has the following formula: (In the formula, R ¹ has 1 to 3 carbon atoms which may contain silicon.
Represents a chain hydrocarbon group up to, or silicon, R ² , R ³ ,
R ⁴ represents a chain hydrocarbon group having 1 to 6 carbon atoms which may contain silicon, and any one of R ² , R ³ and R ⁴ may be hydrogen. 0.01% by weight of a branched chain olefin polymer comprising a repeating unit represented by the formula (hereinafter sometimes abbreviated as a specific branched chain olefin polymer).
This is a titanium trichloride composition (III) containing 99% by weight, and its production method will be described.

The titanium trichloride composition (III) is produced as follows. First, a reaction product (I) is obtained by reacting an organoaluminum compound (A ₁ ) with an electron donor (B ₁ ) and a solid product obtained by reacting this (I) with titanium tetrachloride. (II) or a solid product (II) obtained by reacting an organoaluminum compound (A ₁ ) with titanium tetrachloride
Is given by (In the formula, R ¹ represents a chain hydrocarbon group having 1 to 3 carbon atoms which may contain silicon, or silicon, and R ² , R ³ , R ⁴
Represents a chain hydrocarbon group having 1 to 6 carbon atoms which may contain silicon, and any one of R ² , R ³ and R ⁴ may be hydrogen. ) Branched chain olefins (hereinafter,
It may be abbreviated as a specific branched chain olefin. )
After the polymerization treatment in ( ₃ ), the electron donor (B ₂ ) and the electron acceptor are further reacted to obtain the titanium trichloride composition (III) used in the present invention.

In the present invention, "polymerizing" means contacting the solid product (II) with a specific branched chain olefin under a condition where the specific branched chain olefin can be polymerized to polymerize the specific branched chain olefin. By the polymerization treatment, the solid product (II) is in a state of being coated with the polymer.

The above-mentioned reaction between the organoaluminum compound (A ₁ ) and the electron donor (B ₁ ) is carried out in the solvent (D) at −20 ° C. to 200 ° C., preferably −10 ° C. to 100 ° C. for 30 seconds to 5 hours. . There is no limitation on the order of addition of the organoaluminum compound (A ₁ ), (B ₁ ), and (D), and the amount ratio used is from 0.1 mol of the electron donor (B ₁ ) to 1 mol of the organoaluminum compound (A ₁ ). 8 mol, preferably 1-4 mol, solvent 0.5 L-5 L, preferably
It is 0.5L-2L.

Thus, the reaction product (I) is obtained. The reaction product (I) can be used for the next reaction in a liquid state as it is after completion of the reaction (sometimes referred to as the reaction product liquid (I)) without separation.

The reaction product (I) is reacted with titanium tetrachloride or the solid product (II) obtained by reacting the organoaluminum compound (A ₁ ) with titanium tetrachloride is polymerized with a specific branched chain olefin. As a method, the reaction product (I),
Alternatively, a method of polymerizing the solid product (II) by adding a specific branched chain olefin at any stage of the reaction between the organoaluminum compound (A ₁ ) and titanium tetrachloride, the reaction product (I), or After completion of the reaction between the organoaluminum compound (A ₁ ) and titanium tetrachloride, a method of polymerizing the solid product (II) by adding a specific branched chain olefin, and the reaction product (I) or organoaluminum After completion of the reaction between the compound (A ₁ ) and titanium tetrachloride, the liquid portion is separated and removed by filtration or decantation, the obtained solid product (II) is suspended in a solvent, and the organoaluminum compound ( A ₁ ), there is a method of adding a specific branched chain olefin and conducting a polymerization treatment.

The reaction of the reaction product (I) or the organoaluminum compound (A ₁ ) with titanium tetrachloride may be carried out with or without addition of a specific branched chain olefin in any process of the reaction.
It is carried out at -10 ° C to 200 ° C, preferably 0 ° C to 100 ° C for 5 minutes to 10 hours.

Although it is preferable not to use a solvent, an aliphatic or aromatic hydrocarbon can be used. The mixing of (I) or the organoaluminum compound (A ₁ ), titanium tetrachloride and the solvent may be carried out in any order, and the addition of the specific branched chain olefin may be carried out at any stage.

The mixing of the total amount of (I) or the organoaluminum compound (A ₁ ), titanium tetrachloride, and the solvent is preferably completed within 5 hours, and the reaction is performed during the mixing. It is preferable to continue the reaction within 5 hours after mixing the whole amount.

The amount of each used in the reaction is 1 to 1 mol of titanium tetrachloride, the solvent is 0 to 3,000 ml, and the reaction product (I) or the organoaluminum compound (A ₁ ) is in the (I) or the (A ₁ ). The ratio of the number of Al atoms to the number of Ti atoms in titanium tetrachloride (Al / Ti) is 0.05 to 10, preferably 0.06 to 0.3.

The polymerization treatment with a specific branched chain olefin is carried out when the specific branched chain olefin is added at any stage of the reaction between the reaction product (I) or the organoaluminum compound (A ₁ ) and titanium tetrachloride. When a specific branched chain olefin is added after the reaction of (I) or the organoaluminum compound (A ₁ ) with titanium tetrachloride, the reaction temperature is 0 to 90 ° C. for 1 minute to 10 hours, and the reaction pressure is large. Atmospheric pressure ~ 10kgf /
0.01 g to 100 g of solid product (II) under the condition of cm ² G
Polymerization is carried out using 100 kg of the specific branched chain olefin so that the content of the specific branched chain olefin polymer in the final titanium trichloride composition (III) is 0.01% by weight to 99% by weight.

If the content of the specific branched chain olefin polymer is less than 0.01% by weight, the effect of improving transparency and crystallinity of the polypropylene produced using the titanium trichloride composition obtained is insufficient, and 99 When the content is more than weight%, the improvement effect is not remarkable and it is economically disadvantageous.

After the reaction of the reaction product (I) or the organoaluminum compound (A ₁ ) with titanium tetrachloride is completed, a polymerization treatment with a specific branched chain olefin is carried out, and then a liquid portion is separated and removed by filtration or decantation, and then obtained. When the obtained solid product (II) is suspended in a solvent, 100 ml to 5,000 ml of a solvent and 0.5 g to 5,000 g of an organoaluminum compound are added to 100 g of the solid product (II) at a reaction temperature of 0. ° C. 1 minute to 10 hours at to 90 ° C., the reaction pressure solid product under the conditions of atmospheric pressure ^{~10kgf / cm 2 G (II)} 100g per using a specific Edakusari olefins 0.01G～100kg, The content of the specific branched chain olefin polymer in the final titanium trichloride composition (III) is 0.0
Polymerization is carried out so as to be 1% by weight to 99% by weight.

The solvent is preferably an aliphatic hydrocarbon, and the organoaluminum compound was used for obtaining the reaction product (I) or used for the reaction with titanium tetrachloride directly without reacting with the electron donor (B ₁ ). It may be the same as or different from the one.

After completion of the reaction, the liquid portion is separated and removed by filtration or decantation, and after further repeating washing with a solvent, the obtained solid product subjected to polymerization treatment (hereinafter referred to as solid product (II-A) (May be said) may be used in the next step while being suspended in the solvent, and may be dried and taken out as a solid to be used.

The solid product (II-A) is then reacted with an electron donor (B ₁ ) and an electron acceptor (F). This reaction can be carried out without using a solvent, but using an aliphatic hydrocarbon gives preferable results.

The amount used is 100 g of solid product (II-A),
(B ₂ ) 0.1 g to 1,000 g, preferably 0.5 g to 200 g, (F) 0.
1g-1,000g, preferably 0.2g-500g, solvent 0-3,000m
l, preferably 100-1,000 ml.

As a reaction method, a solid product (II-A) is reacted with an electron donor (B ₂ ) and an electron acceptor (F) at the same time, and after (II-A) is reacted with (F), ( a method of reacting B _2), was reacted with (B ₂₎ to (II-a),
There are a method of reacting (F) and a method of reacting (B ₂ ) with (F) and then reacting with (II-A), but any method may be used.

The reaction conditions are 40 ° C. to 20 ° C. in the above method.
It is desirable to carry out the reaction at 0 ° C., preferably 50 ° C. to 100 ° C. for 30 seconds to 5 hours, and in the method of (II-A) and (B ₂ ) the reaction is performed at 0 ° C. to 50 ° C. for 1 minute to 3 hours. After the reaction, (F) is reacted under the same conditions as described above.

In the other method, (B ₂ ) and (F) are heated at 10 ℃ to 100 ℃.
After reacting for 30 minutes to 2 hours, cool to 40 ° C or lower (II
After the addition of -A), the reaction is carried out under the same conditions as above.

After the reaction of the solid products (II-A), (B ₂ ) and (F) is completed, the liquid portion is separated and removed by filtration or decantation, and then the washing with a solvent is repeated to obtain the specific product used in the present invention. 0.001% by weight of branched chain olefin polymer to 99
A titanium trichloride composition (III) is obtained which contains wt%.

The organoaluminum compound (A ₁ ) used for producing the titanium trichloride composition (III) used in the present invention has a general formula:
AlR ⁵ _p R ⁶ _{p ′} X _{3- (p + p ′)} (In the formula, R ⁵ and R ⁶ represent a hydrocarbon group such as an alkyl group, a cycloalkyl group, an aryl group or an alkoxy group, and X represents a halogen; p,
p'represents an arbitrary number of 0 <p + p'≤3. ) Is used.

Specific examples thereof include trimethyl aluminum, triethyl aluminum, tri n-propyl aluminum and tri n-
Butyl aluminum, tri i-butyl aluminum, tri
Tri-alkyl aluminums such as n-hexyl aluminum, tri i-hexyl aluminum, tri 2-methylpentyl aluminum, tri n-octyl aluminum, and tri n-decyl aluminum, diethyl aluminum monochloride, di n-propyl aluminum monochloride, di
Dialkyl aluminum monohalides such as i-butyl aluminum monochloride, diethyl aluminum monofluoride, diethyl aluminum monobromide, diethyl aluminum monoiodide, etc., dialkyl aluminum hydrides such as diethyl aluminum hydride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride Alkyl aluminum sesquihalides such as, aluminum aluminum dichloride, monoalkyl aluminum dihalides such as i-butyl aluminum dichloride, and the like. In addition, alkoxyalkyl aluminums such as monoethoxydiethylaluminum and diethoxymonoethylaluminum are used. You can also Two or more kinds of these organoaluminum compounds may be mixed and used.

As the electron donor used in the present invention, various ones shown below are shown. As (B ₁ ) and (B ₂ ), ethers are mainly used, and other electron donors are shared with ethers. Is preferred. What is used as an electron donor is an organic compound having any atom of oxygen, nitrogen, sulfur and phosphorus, that is, ethers, alcohols, esters, aldehydes, fatty acids, ketones, nitriles,
Amines, amides, urea or thioureas, isocyanates, azo compounds, phosphines, phosphites,
Examples include phosphinites, hydrogen sulfide or thioethers, and thioalcohols. Specific examples include diethyl ether, di-n-propyl ether, di-n-butyl ether,
Diisoamyl ether, di n-pentyl ether, di n-hexyl ether, di i-hexyl ether, di n-octyl ether, di i-octyl ether, di n-dodecyl ether, diphenyl ether, ethylene glycol monoethyl ether, tetrahydrofuran, etc. Ethers, methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, phenol,
Alcohols such as cresol, xylenol, ethylphenol, naphthol, or phenols, methyl methacrylate, ethyl acetate, butyl formate, amyl acetate,
Vinyl butyrate, vinyl acetate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl benzoate, benzoic acid
2-ethylhexyl, methyl toluate, ethyl toluate, 2-ethylhexyl toluate, methyl anisate, ethyl anisate, propyl anisate, ethyl cinnamate, methyl naphthoate, ethyl naphthoate, propyl naphthoate, butyl naphthoate , 2-ethylhexyl naphthoate,
Esters such as ethyl phenylacetate, aldehydes such as acetaldehyde and benzaldehyde, formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, succinic acid, fatty acids such as acrylic acid and maleic acid, aromatic acids such as benzoic acid, methyl ethyl ketone, Methyl isobutyl ketone, ketones such as benzophenone, nitriles such as acetonitrile, methylamine, diethylamine, tributylamine, triethanolamine, β (N, N-dimethylamino) ethanol, pyridine, quinoline, α-picoline,
Amine such as 2,4,6-trimethylpyridine, N, N, N ′, N′-tetramethylethylenediamine, aniline, dimethylaniline, formamide, hexamethylphosphoric triamide, N, N, N ′, N ′, N ″ -pentamethyl-N′-β-dimethylaminomethylphosphoric triamide, octamethylpyrophosphoramide and other amides, N, N, N′-N′-tetramethylurea and other ureas, phenyl isocyanate, toluyl Isocyanates such as isocyanate, azo compounds such as azobenzene, ethylphosphine, triethylphosphine, tri-n-butylphosphine, tri-n-octylphosphine, triphenylphosphine, phosphines such as triphenylphosphine oxide, dimethylphosphite, di-n- Octyl phosphite, triethyl phosphite, tri-n-butyl phosphite , Phosphites such as triphenylphosphite, ethyldiethylphosphinite, ethylbutylphosphinite, phosphinites such as phenyldiphenylphosphinite, diethylthioether, diphenylthioether, methylphenylthioether, ethylene sulfide, propylene sulfide And the like, and thioalcohols such as ethylthioalcohol, n-propylthioalcohol, thiophenol, etc. These electron donors can also be used as a mixture. Each of the electron donor (B ₁ ) and the solid product (II-A) (B ₂ ) for obtaining the compound may be the same or different.

The electron acceptor (F) used in the present invention is represented by the periodic table III to V.
It is represented by halides of Group I elements. Specific examples include anhydrous aluminum chloride, silicon tetrachloride, stannous chloride, stannic chloride, titanium tetrachloride, zirconium tetrachloride, phosphorus trichloride, phosphorus pentachloride, vanadium tetrachloride, antimony pentachloride and the like. These can also be used as a mixture. Most preferred is titanium tetrachloride.

The following solvents are used. Examples of the aliphatic hydrocarbon include n-pentane, n-hexane, n-heptane, n-octane, i-octane and the like, and carbon tetrachloride, chloroform instead of or together with the aliphatic hydrocarbon. It is also possible to use halogenated carbon hydrogen such as dichloroethane, trichloroethylene, and tetrachloroethylene.

As an aromatic compound, an aromatic hydrocarbon such as naphthalene,
And its derivatives, mesitylene, durene, ethylbenzene, isopropylbenzene, 2-ethylnaphthalene,
Alkyl-substituted compounds such as 1-phenylnaphthalene, halides such as monochlorobenzene, chlorotoluene, chlorxylene, chloroethylbenzene, dichlorobenzene and bromobenzene are shown.

Specific branched chain olefins used in the polymerization treatment have the following formula: (In the formula, R ¹ has 1 to 3 carbon atoms which may contain silicon.
Represents a chain hydrocarbon group up to, or silicon, R ² , R ³ ,
R ⁴ represents a chain hydrocarbon group having 1 to 6 carbon atoms which may contain silicon, and any one of R ² , R ³ and R ⁴ may be hydrogen. ) Is a branched chain olefin. Specific examples thereof include vinyltrimethylsilane, vinyltriethylsilane, vinyltrin-butylsilane, allyltrimethylsilane, allylethyldimethylsilane,
Alkenylsilanes such as allyldiethylmethylsilane, allyltriethylsilane, allyltri-n-propylsilane, 3-butenyltrimethylsilane, and 3-butenyltriethylsilane, and diamines such as dimethyldiallylsilane, ethylmethyldiallylsilane, and diethyldiallylsilane. Examples thereof include allylsilanes, and one or more kinds of these specific branched chain olefins are used.

The titanium trichloride composition (III) and the organoaluminum compound (A ₂ ) obtained as described above, and the organosilicon compound (S) having a Si—OC bond and / or a mercapto group (hereinafter, organosilicon compound ( S) may be abbreviated.) In a predetermined amount described later,
The catalyst used in the present invention, or more preferably, the catalyst is used as a catalyst pre-activated by reacting α-olefin.

The polymerization mode of propylene polymerization using the above catalyst is not limited, and it can be suitably carried out not only in liquid phase polymerization such as slurry polymerization and bulk polymerization but also in gas phase polymerization. A catalyst obtained by combining a titanium trichloride composition (III) with an organoaluminum compound (A ₂ ) and an organosilicon compound (S) is sufficiently effective for slurry polymerization or bulk polymerization, but is used for gas phase polymerization. In this case, a titanium trichloride composition (III) is replaced with a titanium trichloride composition (III) and an organoaluminum compound, and this is reacted with an α-olefin to be preactivated to obtain a higher activity. It is desirable to use a catalyst component. When performing gas phase polymerization following slurry polymerization or bulk polymerization, even if the catalyst initially used is the former, it is the same as the latter catalyst because the reaction of propylene has already been carried out during gas phase polymerization. And an excellent effect can be obtained.

Pre-activation is based on 1 g of titanium trichloride composition (III),
Organoaluminum compound 0.005 g to 500 g, solvent 0 to 50 l,
Hydrogen 0 to 1,000 ml, and α-olefin 0.01 g to 5,000
g, preferably 0.05g to 3,000g, 1 at 0 ° C to 100 ° C
Reaction with α-olefin for minutes to 20 hours, 0.01 g to 2,000 g, preferably 0.05 g per 1 g of titanium trichloride composition (III)
It is desirable to polymerize ~ 200 g of α-olefin.

The reaction of α-olefin for preactivation is n-pentane,
It can be performed in an aliphatic or aromatic hydrocarbon solvent such as n-hexane, n-heptane, or toluene, or in a liquefied α-olefin such as liquefied propylene or liquefied butene-1 without using a solvent. -The olefin can be reacted in the gas phase, or can be preliminarily allowed to coexist with the α-olefin polymer and hydrogen. It is also possible to add the organosilicon compound (S) in advance in the preliminary activation.

Examples of the α-olefin used for preactivating include ethylene, propylene, butene-1, pentene-
1, straight-chain monoolefins such as 1, hexene-1, heptene-1, octene-1, etc., branched chain monoolefins such as 4-methyl-pentene-1, 2-methyl-pentene-1, etc. .Alpha.-olefins are used. Also,
As the organoaluminum compound, those similar to the above-mentioned (A ₁ ) can be used, but preferably a dialkylaluminum monohalide similar to the below-mentioned (A ₂ ) is used.

After completion of the pre-activation reaction, the catalyst prepared by adding a predetermined amount of the organosilicon compound (S) to the pre-activation catalyst component slurry can be used as it is for the polymerization of propylene, or the coexisting solvent, The α-olefin and the organoaluminum compound in the reaction are removed by filtration or decantation, and dried powder or a suspension is prepared by adding a solvent to the powder and the organoaluminum compound (A ₂ ) and A method of using as a catalyst in combination with an organosilicon compound (S), a method of providing for the polymerization of propylene, a coexisting solvent, and unreacted α-olefin are evaporated and removed by distillation under reduced pressure, or an inert gas flow, etc. and a state of being suspended by adding a solvent to the body or powder granules, add the organoaluminum compound (a ₂₎ as required to the ones, further organosilicon By combining the compound (S) as a catalyst, it is also possible to use in the polymerization of propylene.

Regarding the amounts of the titanium trichloride composition (III), the organoaluminum compound (A ₂ ) and the organosilicon compound (S) used during the polymerization of propylene, the organosilicon compound (S) and the titanium trichloride are used. The molar ratio (S) / (III) of the composition (III) is 1.0 to 10.0, or the molar ratio (A ₂ ) / (III) of the organoaluminum compound (A ₂ ) and the titanium trichloride composition (III). Is 0.1 to 200, preferably 0.1 to 100.

When the addition amount of the organosilicon compound (S) is small, the crystallinity is insufficiently improved, so that the rigidity is not high, and when the addition amount is too large, the polymerization activity decreases, which is not practical. The number of moles of the titanium trichloride composition (III) is substantially included in (III).
Ti gram means the number of atoms.

As the organoaluminum compound (A ₂ ) to be combined with the titanium trichloride composition (III) during the polymerization of propylene, a dialkylaluminum monohalide represented by the general formula of AlR ⁷ R ⁸ X is preferable. In the formula, R ⁷ and R ⁸ represent a hydrocarbon group such as an alkyl group, a cycloalkyl group, an aryl group, an alkaryl group or an alkoxy group, and X represents halogen. Specific examples thereof include diethylaluminum monochloride, di-n-propylaluminum monochloride, di-i-butylaluminum monochloride, di-n-butylaluminum monochloride, diethylaluminum monoiodide, diethylaluminum monobromide and the like.

Organosilicon compound (S) having Si-OC bond and / or mercapto group which is another component constituting the catalyst
As specific examples that can be used as, methyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane, trimethylmethoxysilane, triphenylmethoxy. Silane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, propyltriethoxysilane, allyltriethoxysilane, pentyltriethoxysilane, phenyltriethoxysilane, n-octyltriethoxysilane, n- Octadecyltriethoxysilane, 6-triethoxysilyl-2-norbornene, dimethyldiethoxysilane, diethyldiethoxysilane,
Diphenyldiethoxysilane, trimethylethoxysilane, triethylethoxysilane, triphenylethoxysilane, allyloxytrimethylsilane, methyltri i-
Propoxysilane, dimethyldi-propoxysilane, trimethyli-propoxysilane, tetra-n-butoxysilane, methyltri-n-butoxysilane, tetra (2-ethylbutoxy) silane, methyltriphenoxysilane, dimethyldiphenoxysilane, trimethylphenoxysilane,
Trimethoxysilane, triethoxysilane, triethoxychlorosilane, tri i-propoxychlorosilane, tri
n-butoxycyclolosilane, tetraacetoxysilane,
Methyltriacetoxysilane, ethyltriacetoxysilane, vinyltriacetoxysilane, methyldiacetoxysilane, diacetoxymethylvinylsilane, dimethyldiacetoxysilane, methylphenyldiacetoxysilane, diphenyldiacetoxysilane, trimethylacetoxysilane, triethylacetoxysilane, phenyl Organosilicon compounds having Si-OC bond such as dimethylacetoxysilane, triphenylacetoxysilane, bis (trimethylsilyl) adibate, trimethylsilylbenzoate, triethylsilylbenzoate, mercaptomethyltrimethylsilane, 2-mercaptoethyltrimethylsilane, 3-mercaptopropyl Trimethylsilane, 4-
Mercapto-n-butyltrimethylsilane, mercaptomethyltriethylsilane, 2-mercaptoethyltriethylsilane, 3-mercaptopropyltriethylsilane, 1-mercaptoethyltrimethylsilane, 3-mercaptopropyldimethylphenylsilane, 4-mercaptopropylethyltylphenylsilane , 4-mercaptobutyldiethylphenylsilane, an organosilicon compound having a mercapto group such as -mercaptopropylmethyldiphenylsilane, mercaptomethyltrimethoxysilane, mercaptomethyldimethylmethoxysilane, mercaptomethyldimethoxysilane, mercaptomethyltriethoxysilane,
Mercaptomethyldiethoxymethylsilane, mercaptomethyldimethylethoxysilane, 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, dimethoxy-3-mercaptopropylmethylsilane, dimethoxy-3-methcaptopropylmethylsilane,
3-mercaptopropyltriethoxysilane, diethoxy-3-mercaptopropylmethylsilane, mercaptomethyldimethyl-2-phenylethoxysilane, 2-mercaptoethoxytrimethylsilane, 3-mercaptopropoxytrimethylsilane, etc.Si-OC bond and mercapto group Organosilicon compounds and 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-aminopropyldimethylethoxysilane, 3-aminophenoxydimethylvinylsilane, 4-aminophenoxydimethyl Vinylsilane, 2-aminoethylaminomethyltrimethoxysilane,
Si-OC bond such as 3- (2-aminoethylaminopropyl) dimethoxymethylsilane, 2-aminoethylaminomethylbenzyloxydimethylsilane, 3- [2- (2-aminoethylaminoethylamino) propyl] trimethoxysilane And an organic silicon compound having an amino group.

The catalyst thus obtained for use in the present invention is used for the polymerization of propylene. As the polymerization method for polymerizing propylene, as described above, the polymerization of propylene is carried out in a hydrocarbon solvent such as n-hexane, n-heptane, n-octane, benzene or toluene, or slurry polymerization, or in liquefied propylene. It can be carried out by bulk polymerization and gas phase polymerization.

Regarding the crystallinity of the polymer capable of exerting the effect of the present invention for the polypropylene obtained by the above-mentioned various polymerization modes, the melt flow rate (MF of polypropylene)
R) and the absorbance ratio by infrared absorption spectroscopy (IR-τ;
Absorbance ratio at infrared wavenumbers 997 cm ^-1 and 973 cm ^-1 , A ₉₉₇
The relationship with / A ₉₇₃ ) is characterized by satisfying the formula of IR−τ ≧ 0.0203log MFR + 0.950. The higher the crystallinity of polypropylene, the higher the IR-π, and the higher the MFR, the IR-π.
Tends to be higher. Practically, the MFR is practically 0.05 to 200, preferably 0.1 to 100. Polymerization temperature is usually 20 to 10
The temperature is 0 ° C, preferably 40 to 85 ° C. If the temperature is too low, the polymerization activity becomes low, which is not practical, and if the temperature is high, it becomes difficult to increase the crystallinity. The polymerization pressure is normal pressure to 50 kg / cm ² G and is usually carried out for about 30 minutes to 15 hours.
At the time of polymerization, the addition of an appropriate amount of hydrogen for controlling the molecular weight is the same as the conventional polymerization method.

Thus, the polypropylene obtained by the method of the present invention is a high-rigidity polypropylene having remarkably high transparency, and is used for various molded articles by the known techniques such as injection molding, vacuum molding, extrusion molding and blow molding. It

[Action]

Although the detailed mechanism of the high-rigidity polypropylene obtained by the method of the present invention is unknown, the high-rigidity polypropylene production performance possessed by the catalyst comprising a predetermined amount of a combination of the catalyst components used in the present invention provides high rigidity. Show. In addition, by dispersing and containing a specific branched chain olefin polymer having a high stereoregularity, the specific branch chain olefin polymer exhibits a nucleating action during melt molding, thereby preventing crystallization of polypropylene. As a result of accelerating, the transparency and crystallinity of the whole polypropylene are increased, and the dispersion state of the specific branched olefin polymer is extremely good as a result of the introduction method of the present invention, so that the occurrence of voids is extremely small. I have to.

Furthermore, since the specific branched chain olefin polymer introduced by the method of the present invention is a stereoregular high molecular weight polymer as described above, it does not bleed to the surface.

〔Example〕

Hereinafter, the present invention will be described with reference to examples. The definitions of terms used in Examples and Comparative Examples and the measuring methods are as follows.

(1) TY: Polymerization activity, polymer yield per 1 gram atom of titanium (unit: kg / gram atom) (2) MFR: Melt flow rate JIS K7210 Conditions 14 in Table 1
(Unit: g / 10 minutes) (3) IR-τ: Temperature 200 ° C, pressure 20 using a press molding machine
A sample was formed into a film by preheating for 1 minute and pressurization for 1 minute under the condition of 0 kg / cm ² G, and then immediately cooled with water at 20 ° C. to obtain a film of about 40 μm. Then, the film was put in an annealing tube, sucked in a vacuum, and annealed in an oil bath at 135 ° C. for 1 hour. 3 from the film after annealing
Cut out a small piece of film, using each of these small films as a measurement sample, the absorbance ratio between ₉₉₇ cm ⁻¹ and 973 cm ⁻¹ , (A ₉₉₇ / A ₉₇₃ ) was measured, and the average value was taken as the IR-τ value. To do. This IR- [tau] measurement was performed with a Perkin Elmer 783 type infrared spectrophotometer.

(4) Internal haze: The haze inside the film excluding the effect of the surface, using a press machine at a temperature of 200 ° C and a pressure of 200 kg.
After making polypropylene film of 150μ thickness under the condition of / cm ² G and applying liquid paraffin on both sides of the film,
The haze was measured according to JIS K7105. (Unit:%) (5) Crystallization temperature: Measured with a differential scanning calorimeter at a descending rate of 10 ° C / min. (Unit: ° C) (6) Rigidity: Tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'] based on 100 parts by weight of polypropylene
Hydroxyphenyl) propionate] methane (0.1 parts by weight) and calcium stearate (0.1 parts by weight) were mixed, and the mixture was granulated using an extruder having a screw diameter of 40 mm. Then, the granulated product is made into a JIS type test piece at a molten resin temperature of 230 ° C. and a mold temperature of 50 ° C. with an injection molding machine, and the test piece is left for 72 hours in a room at a humidity of 50% and a room temperature of 23 ° C. Was measured by the following method.

(A) Flexural modulus: JIS K7203 compliant (Unit: kgf / cm ² ) (B) Tensile strength: JIS K7113 compliant (Unit: kgf / cm ² ) (C) Rockwell hardness (R scale): JIS K7202 Compliant (d) Heat distortion temperature (HDT): Compliant with JIS K7202 (Unit:
(7) Void: Polypropylene was granulated in the same manner as in the previous section, and the granules obtained were extruded at a molten resin temperature of 250 ° C using a T-die type film forming machine, and then cooled with a 20 ° C cooling roll. Thickness 1mm
Created a sheet of. The sheet was heated with hot air at 150 ° C. for 70 seconds and stretched 7 times in the machine and transverse directions using a biaxial stretching machine to obtain a biaxially stretched film having a thickness of 20 μm. The film was observed with an optical microscope, and the number of voids having a diameter of 10 μm or more was measured, and less than 20 per 1 cm ² was indicated by ◯, 20 or more and less than 50 by Δ, and 50 or more by x.

Example 1 (1) Preparation of titanium trichloride composition (III) n-hexane 6 l, diethylaluminum monochloride (DEAC) 5.0 mol, diisoamyl ether 12.0 mol 25
Mix for 1 minute at ℃ and react for 5 minutes at the same temperature to obtain reaction product (I) (diisoamyl ether / DEAC molar ratio 2.4)
Got

Put 40 mol of titanium tetrachloride in a reactor purged with nitrogen and
It is heated to ℃, and the total amount of the above reaction product liquid (I) is added to
After dripping in minutes, keep at the same temperature for 60 minutes, raise to 80 ° C and react for 1 hour, cool to room temperature, remove the supernatant, add 20 liters of n-hexane, and decant to obtain the supernatant. The operation except for was repeated 4 times to obtain a solid product (II).

The whole amount of (II) was suspended in 30 l of n-hexane, 400 g of diethylaluminum monochloride was added, 6.3 kg of allyltrimethylsilane was added at 40 ° C., and a polymerization treatment was performed at 40 ° C. for 2 hours. After treatment, raise the temperature to 50 ° C and remove the supernatant liquid.
The operation of adding 30 liters of hexane and removing the supernatant by decantation was repeated 4 times to obtain a solid product (II-A) subjected to polymerization treatment.

With the total amount of this solid product suspended in 9 l of n-hexane, 3.5 kg of titanium tetrachloride was added at room temperature over about 10 minutes,
After reacting at 0 ° C for 30 minutes, 1.6 kg of diisoamyl ether was further added, and the mixture was reacted at 80 ° C for 1 hour. After the reaction was completed, the operation of removing the supernatant was repeated 5 times and then dried under reduced pressure to obtain a titanium trichloride composition (III). The content of allyltrimethylsilane polymer in the obtained titanium trichloride composition (III) was 50.0% by weight, and the titanium content was 12.6% by weight.

(2) Preparation of pre-activated catalyst component After replacing a stainless steel reactor with an inclined blade with an internal volume of 150 l with nitrogen gas, 100 l of n-hexane, 114 g of diethylaluminum monochloride 114, titanium trichloride composition obtained in (1) After adding 1.8 kg of the compound (III) at room temperature and supplying 1.8 Nm ^{3 of} ethylene at 30 ° C. for 2 hours to cause a reaction (1 g of the titanium trichloride composition (III) reacts with 1.0 g of ethylene), Unreacted ethylene was removed, washed with n-hexane and then dried to obtain a preactivated catalyst component.

(3) Polymerization of Propylene n-Hexane was added to the pre-activated catalyst component obtained in (2) above in a polymerization vessel equipped with a two-stage turbine blade with an internal volume of 200 l and equipped with a stirrer, and 4.0 wt% n-hexane suspension After being made into a liquid, the suspension had a molar ratio of 12.5 mg atom / hr in terms of titanium atom, and diethyl aluminum monochloride and 3-aminopropyltriethoxysilane were used so that the molar ratio was 4.0 and 2.5, respectively, with respect to the titanium atom. N-Hexane was continuously supplied at 21 kg / hr from the same pipe or another pipe. Furthermore, hydrogen was supplied so that the concentration in the gas phase of the polymerization vessel was maintained at 2.3% by volume, and propylene was supplied so that the total pressure was maintained at 10 kg / cm ² G, and continuous polymerization of propylene was continuously performed for 120 hours. I went.

During the polymerization period, the slurry retention level in the polymerization vessel was 75
The slurry was continuously withdrawn from the polymerization vessel to a flash tank having an internal volume of 50 l so as to have a volume%. Depressurized in the flash tank to remove unreacted propylene and hydrogen, while methanol was supplied at 1 kg / hr at 70 ° C.
Was contact-treated. Subsequently, after neutralizing with an aqueous solution of sodium hydroxide, the polymer is washed with water, separated and dried, and then MF
A product polypropylene of R2.0 was obtained at 10 kg / hr.

Comparative Example 1 (1) In the same manner as in (1) of Example 1, except that the solid product (II) was replaced with the solid product (II-A) without the polymerization treatment with allyltrimethylsilane. A titanium trichloride composition was obtained.

(2) In the same manner as in (2) of Example 1, except that the titanium trichloride composition (III) obtained in (1) above was used instead of the titanium trichloride composition (III), The preparation was done.

(3) In (3) of Example 1, the pre-activated catalyst component obtained in (2) above is used as the pre-activated catalyst component, and each catalyst component is maintained so that the total pressure is maintained at 10 kg / cm ² G. Polypropylene was obtained in the same manner except that was charged into the polymerization vessel.

Examples 2 and 3 In (3) of Example 1, the hydrogen concentration in the gas phase of the polymerization vessel was changed to 3.5% by volume (Example 2) and 8.7% by volume (Example 3), and the total pressure was changed. Polypropylene was obtained in the same manner as in Example 1 except that each catalyst component was supplied to the polymerization vessel so as to maintain 10 kg / cm ² G.

Comparative Examples 2 and 3 In (3) of Comparative Example 1, the hydrogen concentration in the gas phase of the polymerization vessel was changed to 3.5% by volume (Comparative Example 2) and 8.7% by volume (Comparative Example 3), and the total pressure was changed. Polypropylene was obtained in the same manner as in Comparative Example 1 except that each catalyst component was supplied to the polymerization vessel so as to keep 10 kg / cm ² G.

Comparative Example 4 (1) A titanium trichloride composition was obtained in the same manner as in Comparative Example 1 (1).

(2) To the reactor used in (2) of Example 1, 100 l of n-hexane, 300 g of diethylaluminum monochloride, and 180 g of the titanium trichloride composition obtained in (1) above were added at room temperature, and then allyl was added. Trimethylsilane (5.2 kg) was added and reacted at 40 ° C for 2 hours (1.0 g per 1 g of titanium trichloride composition)
reaction). After completion of the reaction, it was washed with n-hexane, filtered and dried to obtain a catalyst component preactivated with allyltrimethylsilane.

(3) Polymerization of propylene was carried out in the same manner as in (3) of Example 1 except that the catalyst component pre-activated with allyltrimethylsilane obtained in (2) above was used as the pre-activated catalyst component. , The generated bulk polymer,
Since the slurry withdrawal pipe was blocked, the production had to be stopped 18 hours after the start of the polymerization.

Comparative Example 5 (1) Titanium trichloride composition obtained in the same manner as in (1) of Comparative Example 1 when the reaction product liquid (I) was reacted with titanium tetrachloride in (1) of Comparative Example 1. Allyltrimethylsilane obtained by polymerizing allyltrimethylsilane (4.3 kg) in 100 l of n-hexane at 60 ° C for 2 hours using 500 g of the product and 120 g of diethylaluminum monochloride as a catalyst, washing with methanol and drying. Silane polymer
1.9 kg was ground in a vibration mill with a capacity of 10 l for 5 hours at room temperature.
A titanium trichloride composition containing 50% by weight of an allyltrimethylsilane polymer was obtained in the same manner except that it was suspended in titanium tetrachloride.

(2) A preactivated catalyst component was obtained in the same manner as in (2) of Example 1 except that the titanium trichloride composition obtained in (1) above was used in place of the titanium trichloride composition (III). .

(3) In (3) of Example 1, the pre-activated catalyst component obtained in (2) above is used as the pre-activated catalyst component, and each catalyst component is maintained so that the total pressure is maintained at 10 kg / cm ² G. Polypropylene was obtained in the same manner except that was charged into the polymerization vessel.

Comparative Example 6 4 L of n-hexane and titanium tetrachloride were placed in a reactor purged with nitrogen.
After adding 10 mol and keeping it at 0 ° C., 4 l of an n-hexane solution containing 8 mol of diethylaluminum monochloride was added dropwise thereto, the temperature was raised to 40 ° C., and the reaction was further performed for 1 hour. Then, after adding 6.3 kg of allyltrimethylsilane, a polymerization treatment was carried out at the same temperature for 2 hours. After the polymerization treatment, the supernatant liquid was removed, 5 l of n-hexane was added, and the operation of removing by decantation was repeated 3 times, and the obtained solid product subjected to the polymerization treatment was suspended in 9 l of n-hexane. . Subsequently, 3.5 kg of titanium tetrachloride
Was added at room temperature and reacted at 90 ° C. for 1 hour. After completion of the reaction, it was washed with n-hexane to obtain a titanium trichloride composition. Propylene was polymerized in the same manner as in Comparative Example 1 except that the titanium trichloride composition was used to obtain polypropylene.

Comparative Example 7 Comparative Example 1 except that the catalyst component, 3-aminopropyltriethoxysilane, was not used in (3) of Example 1.
Polypropylene was obtained in the same manner as in.

Comparative Example 8 and Examples 4 and 5 In (1) of Example 1, dimethyldiallylsilane was used instead of allyltrimethylsilane, and the amount of each was changed to 0.2 g, 800 g, and 32 kg to carry out polymerization treatment. Also, in (3), phenyltriethoxysilane is supplied to the polymerization reactor in place of 3-aminopropyltriethoxysilane so that the molar ratio to titanium atoms in the titanium trichloride composition (III) is 2.0. A polypropylene was obtained in the same manner as in Example 1 except for the above.

Comparative Examples 9 to 11 and Examples 6 and 7 In Example 1 (1), 2.7 kg of 3-methylbutene-1 was used instead of allyltrimethylsilane.
Further, in (3), dimethoxy-3-mercaptopropylmethylsilane was used instead of 3-aminopropyltriethoxysilane, and the molar ratio to the titanium trichloride composition (III) was changed as shown in the table. ,
Polypropylene was obtained in the same manner as in Example 1.

The catalyst systems of Examples 1 to 5 and Comparative Examples 1 to 8 below, polymerization results, and evaluation results are shown in the table below.

[Effects of the Invention] The main effects of the present invention are that the occurrence of voids is extremely small, without causing problems in production such as formation of a lump polymer,
That is, polypropylene having extremely high transparency and rigidity can be obtained.

As is apparent from the above-mentioned examples, the internal haze of the film produced by using the polypropylene obtained by the method of the present invention is the titanium trichloride composition obtained without the polymerization treatment with the specific branched chain olefins. Compared with the case of using the polypropylene obtained by using, it is about 1/7 to 1/4, and has extremely high transparency. (See Examples 1 to 5 and Comparative Examples 1 to 3 and 7) Further, the crystallization temperature is increased by about 8 ° C to 9 ° C as compared with the polypropylene obtained by the method of the prior invention, and the crystallinity is remarkably high. As a result, the bending elastic modulus is further improved. (Refer to Examples 1 to 5 and Comparative Examples 1 to 3) Further, it is clear that the number of generated voids is significantly smaller than that of polypropylene introduced with a specific branched chain olefin polymer by a method other than the present invention. is there.
(See Examples 1 to 5 and Comparative Examples 4 and 5)

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram (flow chart) for explaining the method of the present invention.

Claims (5)

[Claims] 1. A solid product obtained by reacting titanium tetrachloride with an organoaluminum compound (A ₁ ) or a reaction product (I) of an organoaluminum compound (A ₁ ) and an electron donor (B ₁ ). (II) is given by (In the formula, R ¹ represents a silicon-containing chain hydrocarbon group having 1 to 3 carbon atoms, or silicon, and R ² , R ³ , and R ⁴ represent 1 to 3 carbon atoms which may contain silicon. 6 represents a chain hydrocarbon group up to 6, but any one of R ² , R ³ and R ⁴ may be hydrogen), and is polymerized with a branched olefin group represented by A titanium trichloride composition (III) obtained by the method of reacting (B ₂ ) with a halide of an element of Group III to VI of the periodic table, comprising the following formula: (In the formula, R ¹ represents a silicon-containing chain hydrocarbon group having 1 to 3 carbon atoms, or silicon, and R ² , R ³ , and R ⁴ represent 1 to 3 carbon atoms which may contain silicon. A branched chain olefin polymer having a repeating unit of up to 6 in which any one of R ² , R ³ and R ⁴ may be hydrogen. % To 99% by weight of a titanium trichloride composition (III), an organoaluminum compound (A ₂ ) and an organosilicon compound (S) having a Si—O—C bond and / or a mercapto group are combined to obtain the organosilicon compound. The molar ratio of the compound (S) to the titanium trichloride composition (III) is (S) / (III) = 1.0 to 10.0, and the organoaluminum compound (A ₂ ) and the titanium trichloride composition (III) are the molar ratio _{(a 2) / (III)} = propylene polymerization of using 0.1 to 200 and the catalyst Method for producing a polypropylene characterized by Rukoto. 2. An organoaluminum compound (A ₁ ) having a general formula of AlR ⁵ _p R ⁶ _{p ′} X _{3- (p + p ′ )} (wherein R ⁵ and R ⁶ are an alkyl group, a cycloalkyl group, A hydrocarbon group such as an aryl group or an alkoxy group, X represents halogen, and p,
p'represents an arbitrary number of 0 <p + p'≤3. The method according to claim 1, wherein an organoaluminum compound represented by the formula (1) is used. 3. The method according to claim 1, wherein a dialkylaluminum monohalide is used as the organoaluminum compound (A ₂ ). 4. A patent using a catalyst component preliminarily activated with a small amount of α-olefin in combination with the titanium trichloride composition (III) instead of the titanium trichloride composition (III). The method according to claim 1. 5. The melt flow rate of polypropylene (MF
R) and the absorbance ratio by infrared absorption spectroscopy (IR-
τ: Absorbance ratio at infrared wave numbers 997 cm ^-1 and 973 cm ^-1 ,
The method according to claim 1, wherein the relationship with A ₉₉₇ / A ₉₇₃ ) satisfies the formula IR−τ ≧ 0.0203 log MFR + 0.950.