JPH0368887B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing propylene polymers (including copolymers) using a Ziegler-Natsuta type catalyst. More specifically, the present invention provides a titanium-containing solid catalyst component (component A) and an organoaluminum obtained by treating a solid composition containing magnesium, titanium, and a halogen as essential components with an organoaluminum compound and an electron donor, and then washing the composition. The present invention relates to a method for producing propylene polymers using a catalyst system consisting essentially of a compound (component B). Prior Art A method for polymerizing olefins using a solid composition in which a tetravalent titanium compound is supported or composited on a magnesium compound as a solid catalyst component of a Ziegler-Natsuta type catalyst is known. There are already many proposals regarding the manufacturing method. One of the characteristics of this supported catalyst component is that the olefin polymerization activity is extremely high. In the polymerization of α-orphine having 3 or more carbon atoms, the stereoregularity ( ) of the resulting polymer can be improved by incorporating a specific electron donor (for example, an aromatic carboxylic acid ester) into the supported catalyst component. It is publicly known. Although these supported catalyst components have a fairly high industrial potential in terms of polymerization activity, bulk density, etc., they are not sufficient for application to rationalized processes based on non-deashing and non-extraction. Ta. Furthermore, the supported catalyst component is uneconomical due to the large amount of organoaluminum compound that must be combined with it, the activity during polymerization decreases markedly over time, and the supported catalyst component lacks storage stability. However, there were problems such as the need for prepolymerization. As a solution to the above problem, JP-A-56-136806
and No. 57-74307. The method described in JP-A-56-136806 is intended to improve storage stability by treating a supported catalyst component with an organoaluminum compound and a small amount of olefin and then drying it. however,
In this proposal, since olefin is used as a treatment component, the volume of the treatment product is high, and the dried powder of the product has poor flowability, making it inconvenient to handle. Furthermore, when the amount of olefin used in the treatment is reduced, there is a drawback that the bulk density of the polymer decreases. On the other hand, the proposal in Japanese Patent Application Laid-open No. 57-74307 is
By treating the supported catalyst component with an organoaluminum compound in the absence of olefin, the aim is to omit prepolymerization, reduce the amount of organoaluminum compound used during main polymerization, improve activity, improve bulk density, etc. . In this method, although the above-mentioned effects can be enjoyed immediately after the treatment, there is a drawback that the activity decreases (in particular, the decrease in activity is significant) as time passes after the treatment. SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks in improving the performance (activity, bulk density) of supported catalyst components of Ziegler-Natsuta type catalysts, omitting prepolymerization, reducing the decline in polymerization activity over time, and stability over time after treatment. This goal is achieved by manufacturing supported catalyst components in a specific manner. Therefore, the method for producing a propylene polymer according to the present invention is a method of polymerizing propylene by bringing it into contact with a catalyst system basically consisting of a titanium-containing solid catalyst component (component A) and an organoaluminum compound (component B). This component A is characterized in that it is as follows. (1) Component A is a solid composition containing magnesium, titanium, and halogen as essential components, in the absence of an olefin, and an organoaluminum compound of the formula H _n R _o AlX _3-(n+o) and the following electron It must be treated with a donor compound and then washed with an inert solvent (in the above formula, R represents a hydrocarbon residue having 1 to 20 carbon atoms, X represents a halogen, m and n is 0≦m<3 and 0, respectively
<n≦3 and 2<m+n≦3); (a) Electron donor compound: a compound selected from carboxylic acid esters and phosphoric acid esters; (2) the above solid composition; The treatment with an organoaluminum compound and an electron donor compound is carried out under the following conditions. (a) Amount of organoaluminum compound/amount of solid composition = 0.1 to 50 (Al/Ti atomic ratio) (b) Amount of electron donor compound/amount of organoaluminum compound = 0.01 to 1.0 (mol/atomic ratio) Effects of the present invention The method provides many benefits, including: (B) Activity improvement (B) Improvement (C) Bulk density improvement (D) No deterioration in performance even after long-term storage after treatment (E) No need for prepolymerization (F) Reduction of activity decline over time during polymerization Many of these effects However, it is difficult to easily infer from the conventionally known facts that the supported catalyst component can be obtained by treating it in the coexistence of an organoaluminum compound and an electron donor compound and then washing it, and it is truly surprising. be. DETAILED DESCRIPTION OF THE INVENTION The titanium-containing catalyst component of the Ziegler-Natsuta type catalyst used in the process of the present invention is prepared by subjecting a specific solid composition to a specific treatment. Solid Composition This solid composition contains magnesium, titanium and halogen as essential components. Here, "consisting of essential components" means that in addition to these three components, other auxiliary components may be included as long as they do not interfere with achieving the objective of the present invention. Examples of such auxiliary ingredients are:
There are electron donor compounds. The composition of this solid composition is arbitrary as long as the purpose of the present invention is achieved, but generally Ti0.1 to 10%
(Depends on weight. The same applies hereinafter), preferably 0.5 to 8%,
More preferably 1.0 to 6.0%, Mg 5 to 50%, preferably 10 to 40%, even more preferably 10 to 30%, halogen 10 to 80%, preferably 20 to 80%, even more preferably 30 to 75%, electron Donor (if used)
It is 1 to 30%, preferably 5 to 20%, and more preferably 7 to 15%. Furthermore, the Mg/Ti atomic ratio is 3~
200, preferably 5-100, particularly preferably 7-100
50, halogen/Ti atomic ratio is 10-100, preferably
15-80, electron donor (if used)/Ti (mol/atomic ratio) 0.05-2, preferably 0.1-1,
More preferably, it is 0.3 to 0.9. The halogen is preferably chlorine. Such a solid composition is essentially the same as the supported catalyst component as described above, and can be used as one produced by a conventionally known method. medium magnesium chloride, a certain dissolving agent,
For example, alcohols such as ethanol, butanol, and octanol, amines such as trimethylamine, triethylamine, and tributylamine, tetra-n-propyl titanate, and tetra-
After dissolving in titanates such as n-butyl titanate, phosphate esters such as tributyl phosphate, trihexyl phosphate, trioctyl phosphate, especially titanates, a halogen compound of titanium such as titanium halide, especially tetra Either by adding titanium chloride or (and) an electron donor compound (if used) (e.g. selected from the exemplified compounds listed below), or by precipitating the magnesium compound from the magnesium compound-containing solution before contacting it with the titanium halide. Preferably, the material is produced by precipitating the solid contained therein and then contacting it with a titanium halogen compound. The solid composition thus obtained may be further treated one or more times with a titanium halogen compound. Preferred examples of such solid compositions include:
JP-A No. 54-40293, No. 58-19307, No. 58-
Supported catalyst components manufactured by the methods disclosed in No. 32604, No. 58-32605, No. 58-117205, and No. 58-183708 can be mentioned. A particularly preferred solid composition for use in the present invention is
No. 40293, No. 58-32604, No. 58-32605, No. 58
-183708 This is a supported catalyst component manufactured by the method described in each publication. Modification Treatment of Solid Composition - Preparation of Component A The most characteristic feature of the present invention is that the solid composition is treated with an organoaluminum compound and an electron donor compound in the absence of an olefin;
and thorough washing with an inert solvent after treatment. The presence of olefins during processing should be avoided since their presence during processing will reduce the bulk density of the target olefin polymer. If an electron donor compound is not used during processing,
Since the catalyst performance (particularly activity) deteriorates significantly during storage after treatment, making it impractical, it is essential to use an electron donor compound at the time of treatment. Furthermore, in the present invention, cleaning after treatment is essential. Even without washing, some of the objects of the present invention can be achieved, but it cannot be said that the decrease in catalyst performance during storage is sufficiently reduced, and the improvement is small. Thorough washing improves storage stability as well. Details of the processing conditions are as follows. (a) Slurry concentration Solid compositions are usually processed while being dispersed in an inert solvent. In this case, the inert solvent is preferably one selected from those exemplified below as a cleaning solvent, and is preferably a solvent for the treating agent, that is, the organoaluminum compound and the electron donor compound. The slurry concentration of the solid composition to be treated is usually 10 to 50,000 mg/liter, preferably 20 to 50,000 mg/liter in terms of titanium atoms contained in the solid composition.
20000mg/liter, particularly preferably 50-10000
mg/liter. A concentration lower than 10 mg/liter is not preferable because the improvement in catalytic activity is small and the bulk density is lowered.
If the concentration is higher than 50,000 mg/liter, stirring becomes difficult and it becomes difficult to remove the reaction heat.
This is not preferred because it may cause adhesion to the reactor, making it difficult to obtain a solid catalyst component with homogeneous properties. (b) Organoaluminum compound The organoaluminum compound that can be used in the treatment of the present invention is represented by the general formula H _n R _o AlX _3-(n+o) . Here, R represents a hydrocarbon residue having 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms, particularly preferably 2 to 12 carbon atoms, X represents a halogen, preferably chlorine, and m and n each represent 0≦m. <3,0
It is a number that satisfies <n≦3 and 2<m+n≦3. Preferred examples of these organoaluminum compounds include triethylaluminum, triisobutylaluminum, triisoprenylaluminum, tridodecylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, a mixture of triethylaluminum and diethylaluminium chloride, triisobutylaluminum and diethyl Mention may be made of mixtures with aluminum chloride.
These organoaluminum compounds may be used alone or in combination of two or more. Particularly preferred examples among these are triethylaluminum and triisobutylaluminum. (c) Al/Ti ratio When a solid composition is treated with an organoaluminum compound and an electron donor compound, the ratio of the organoaluminum compound to titanium contained in the solid composition (Al/Ti atomic ratio) is 0.1 to 50, preferably
0.3-20, particularly preferably 0.5-10. If this ratio is too small, sufficient effects cannot be obtained.
Moreover, if this ratio exceeds the above range, it is not only uneconomical but also undesirable, since there may be a decrease in activity, particularly. (d) Electron donor compound The electron donor compound that can be used in the treatment of the present invention is a compound selected from carboxylic acid esters and phosphoric acid esters. Diethyl carbonate, ethyl formate, ethyl acetate, butyl butyrate, ethyl acrylate, ethyl methacrylate,
Ethyl crotonate, ethyl cyclohexanecarboxylate, methyl benzoate, ethyl benzoate, butyl benzoate, phenyl benzoate, benzyl benzoate, methyl toluate, ethyl toluate, amyl toluate, methyl anisate, ethyl anisate, phthal Carboxylic acid esters having 2 to 20 carbon atoms, such as dimethyl acid, diethyl phthalate, ethyl naphthoate, and γ-butyrolactone;
triethyl phosphate, tributyl phosphate, triphenyl phosphate, diethyl phenylphosphonate,
Phosphate esters such as diphenyl ethylphosphonate and ethyl diphenylphosphinate are preferred, and among these examples, carboxylic esters are particularly preferred. Among the carboxylic esters, aromatic carboxylic esters are most preferred. Suitable examples of aromatic carboxylic acid esters include lower alkyl esters such as benzoic acid, lower alkyl-substituted benzoic acid, and lower alkoxy group-substituted benzoic acid. Here, lower means one having 1 to 5 carbon atoms. Examples of suitable aromatic carboxylic acid esters include methyl benzoate, ethyl benzoate, butyl benzoate, methyl toluate, ethyl toluate, methyl anisate, ethyl anisate, and the like. (e) Electron donor compound/Al ratio The amount of the electron donor compound used in the treatment of the present invention is such that the electron donor/organoaluminum compound ratio (mol/Al atomic ratio) is 0.01 to 1.0, preferably 0.05 to 0.8. , particularly preferably from 0.1 to 0.7. If the amount of the electron donor compound used is too small, the storage stability after treatment will be poor, and if it is too large, the activity will be reduced. (F) Inert Solvent As mentioned above, in the process of the present invention, the solid composition is used in the form of a slurry in an inert solvent. Although the organoaluminum compound and the electron donor compound can be used without being diluted, they are usually used after being diluted with an inert solvent. At this time, the slurry concentration after treatment (before cleaning) is
The amount should be 1 to 50,000 mg/liter in terms of titanium atoms (as described above). The inert solvent used in this treatment is a solvent that does not adversely affect the polymerization performance of the supported catalyst component, and is usually a hydrocarbon. For example, hexane, heptane, decane, kerosene, benzene,
Toluene, xylene, etc. are preferably used, and among them, hexane, heptane, and toluene are preferably used. (g) Order of contact There is no particular restriction on the order of contact of each component during treatment. Specifically, for example, (a) a method of adding an organoaluminum compound and then an electron donor compound to a slurry of a solid composition; (b) a method of adding an electron donor compound to a solid composition slurry and then adding an organoaluminum compound; (c) a method in which a mixture of an organoaluminum compound and an electron donor compound is brought into contact with each other in advance is added to the solid composition slurry, and the method (c) is preferably used. In the case of (c), the effect of the present invention may be weakened due to a secondary reaction between the organoaluminum compound and the electron donor compound, so the next solid composition should be prepared as soon as possible after contact between the two. It is preferable to use it in contact with. (H) Treatment temperature and time The treatment temperature and time are usually -50 to 150°C for about 1 second to about 10 hours, preferably -10 to 100°C for about 5 seconds to about 5 hours, particularly preferably -5 to about 10 hours. 80℃
It takes about 1 minute to about 1 hour. (li) Cleaning In the present invention, cleaning after treatment is essential. As the cleaning solvent, the same type of inert solvent as used in the above-mentioned treatment is used, and among them, saturated aliphatic hydrocarbons such as hexane and heptane are preferred. It is desirable that the washing be carried out until substantially no titanium and aluminum are detected in the washing liquid. For example, when the solid composition used for treatment weighs 1 g, it is washed with 100 ml of heptane about 3 to 10 times. By this washing, the storage stability and catalytic performance of the produced solid catalyst component (A) are further improved compared to those without washing. The reason for this is not clear, but it is thought that it is because unnecessary organoaluminum compounds and electron donor compounds are washed away, and trace amounts of soluble or extremely small titanium components are also removed. Polymerization of propylene (a) Organoaluminum compound In the present invention, the solid catalyst component is combined with an organoaluminum compound and subjected to the polymerization of propylene. As the organic aluminum compound, those represented by the following formula are preferable. ^{R 1 a} _{Al ( OR} ^{2 )} b may also be used.X is fluorine, chlorine, bromine,
and a halogen atom or hydrogen atom selected from iodine. a, b and c are each 0
(It is a positive number satisfying <a≦3, 0≦b<3, 0≦c<3, and a+b+c=3) This organoaluminum compound is a compound with a group metal of the periodic table or a group metal compound. , or in the form of a reaction product of these with water, alcohol, primary or secondary amine, sulfuric acid, hydrogen sulfide, aluminum halide, etc., but it can be used as the organoaluminum compound itself represented by the above formula. It is preferable. Specific examples of the organoaluminum compound represented by the above formula are as follows. (a) Trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-i-propylaluminum, tri-n-butylaluminum, tri-i-butylaluminum, tri-sec-butylaluminum, trihexylaluminum, trioctyl Aluminum, trihydrocarbylaluminum such as triisoprenylaluminum, (b) diethylaluminum chloride, di-n-propylaluminum chloride, di-n-butylaluminum chloride, di-i-butylaluminum chloride, di-sec-butylaluminum chloride , dihydrocarbyl aluminum halides such as diethyl aluminum bromide, (c) dihydrocarbyl aluminum hydrides such as diethyl aluminum hydride and dibutyl aluminum hydride, (d) hydrocarbyl aluminum sesquihalides such as ethyl aluminum sesquichloride and butyl aluminum sesquichloride, (e) Hydrocarbyl aluminum dihalides such as ethyl aluminum dichloride, propyl aluminum dichloride, butyl aluminum dichloride, dihydrocarbyl aluminum alkoxides or aryoxides such as (h)diethyl aluminum ethoxide, diethylaluminum (2,6-di-tert-butyl) phenoxide, etc. These may be used alone or in combination of two or more. Examples of periodic table group or group metal compounds that may be used in combination with the organoaluminum compound represented by the above formula include organic alkali metal compounds such as ethyllithium, butyllithium, and phenyllithium, and diethylmagnesium. , organic alkaline earth metal compounds such as ethylbutylmagnesium and butylmagnesium chloride, and organic compounds of group b metals such as diethylzinc and dibutylcadmium. Among the organoaluminum compounds represented by the above formula, trihydrocarbylaluminum, dihydrocarbylaluminum hydride,
Hydrocarbyl aluminum halides or mixtures thereof are preferably used. The amount of organoaluminum compound used is usually 1 to 1 gram atom of titanium in the solid catalyst component.
1000 mol, preferably 5 to 800 mol, particularly preferably 10 to 500 mol. Organoaluminum compounds can also be used in the form of adducts or reactants with electron donor compounds. In this case, the electron donor may be used by forming an adduct or reactant with the organoaluminum compound in advance, or it may be added individually to the polymerization vessel and the adduct or reactant may be formed in the polymerization vessel. . Examples of the electron donor compound include those used in the treatment of the present invention. Among these, use of aromatic carboxylic acid esters is particularly preferred in order to obtain high-quality polyα-olefins. The amount of the electron donor compound to be used is generally 0.01 to 1 mol, preferably 0.05 to 0.8 mol, and more preferably 0.08 to 0.6 mol, per 1 mol of the organoaluminum compound. (b) Polymerization of propylene In the present invention, a method for polymerizing propylene,
There are no particular limitations on the conditions and the method for controlling the molecular weight of polypropylene, and conventionally known methods and conditions can be used. These include gas phase methods in which the monomers are kept in a substantially gaseous phase without using a liquid medium, slurry and solution methods in which the monomers are kept in a liquid medium and the monomers are kept in a liquid other than water. Any liquid phase bulk method that does not substantially use a medium can be used. The polymerization conditions are also the usual conditions used for polymerization using a Ziegler-Natsuta catalyst. That is, 0~
300℃, preferably 20-250℃, especially 50-200℃
At normal pressure ~ 500Kg/cm ² , preferably 2 ~ 100Kg/cm 2
Polymerization can be carried out under a pressure of cm ² . In the present invention, a high-strength propylene polymer can be obtained in high yield, and there is little decrease in activity and molecular weight when controlling the molecular weight with _H2 . Furthermore, in the method according to the present invention, the particle size and particle size distribution of the produced polymer are good, and handling is extremely easy. EXPERIMENTAL EXAMPLE In order to further specifically illustrate the present invention, an experimental example will be given and explained below. In this experimental example, CY (Ti) is 1 g of titanium atom.
Polymer yield (Kg/g-Ti) obtained from CY
(SC) is the polymer yield obtained from 1 g of solid catalyst component (Kg/g-SC), (A) is the proportion (%) of the residue in the powdered polymer after extraction with boiling n-heptane for 6 hours, T- is the total polymer (the sum of easily soluble polymer recovered from the solvent and powdered polymer)
BD is the bulk density of the polymer (g/
ml) and MI respectively represent the melt viscosity index (g/10 min) of the polymer measured according to ASTM D-1238. Example of manufacturing a solid component 1 5 g of commercially available anhydrous magnesium chloride was mixed with 25 g of toluene.
ml of slurry, 37.4 g of tetra-n-butyl titanate was added thereto, and the mixture was heated at 90°C for 2 hours to obtain a homogeneous solution containing magnesium. A solution prepared by adding 1.5 g of ethyl benzoate to this solution and a solution prepared by dissolving 20.9 g of titanium tetrachloride in 25 ml of toluene were heated to 35 ml of toluene and vigorously stirred at 20°C.
ml simultaneously over 1 hour. A solid precipitates out as the mixture is added dropwise. After the dropwise addition was completed, the mixture was aged at 20°C for 1 hour, and then left to stand and 2/3 of the supernatant was removed. Next, 80 ml of toluene and 69 g of titanium tetrachloride were added in this order to the remaining slurry, and the mixture was stirred at 80°C for 2 hours. The supernatant was removed by decantation and washed twice with 100 ml of toluene. 69 g of titanium tetrachloride was added to the thus obtained slurry, heated at 80° C. for 2 hours, and the washing operation was repeated twice, followed by washing 10 times with 100 ml of heptane to obtain a solid composition.
This solid composition contains 4.14% Ti (wt%), 17.6% Mg, 10.4% ethyl benzoate, and chlorine.
65.7% were included. Example 1 (a) Preparation of solid catalyst component A 114 mg of triethylaluminum and 49.2 mg of ethyl p-toluate were added in this order to 50 ml of heptane at 0°C, stirred for 5 minutes, heated to 20°C, and prepared as described above. Add 40 ml of the solid composition slurry prepared in Production Example 1 (containing 48 mg of titanium), stir at 20°C for 10 minutes, leave to stand, remove the supernatant by decantation, and wash with 100 ml of heptane five times. ,
Solid catalyst component A was obtained. This solid catalyst component contained 4.07% titanium. (b) Polymerization of propylene In a 1 liter autoclave under a propylene atmosphere at 20°C, 500 ml of heptane, 95.4 mg of triethyl aluminum, 51.7 mg of ethyl aluminum sesquichloride, 41.1 mg of ethyl p-toluate,
Then, add in this order an amount equivalent to 0.4 mg of the above solid catalyst component A in terms of titanium atoms, charge hydrogen gas in an amount equivalent to 180 ml in standard conditions, and pressurize propylene gas to make the total pressure 1
After prepolymerization was carried out at 20°C for 15 minutes while maintaining the pressure at 7 kg/cm ² , the temperature was raised to 70°C, propylene was press-injected, and main polymerization was carried out for 2 hours while maintaining the total pressure at 7 kg/cm ² .
The autoclave was opened and the solid polymer was separated by filtration, while the liquid was concentrated to recover the soluble polymer. The results are shown in Table 1. Example 2 Using the solid catalyst component A obtained in Example 1, propylene polymerization was repeated according to the method of Example 1 without prepolymerization. The results are shown in Table 1. Comparative Example 1 Polymerization of propylene was carried out according to the method of Example 1, using the solid composition prepared in Preparation Example 1 instead of solid catalyst component A without carrying out the treatment according to the invention. The results are shown in Table 1. Comparative Example 2 Example 2 was repeated using the solid composition prepared in Preparation Example 1 instead of solid catalyst component A without treatment according to the invention. The results are shown in Table 1. Example 3 Example 1 was repeated except that the propylene polymerization was changed to 6 hours. The results are shown in Table 1. Comparative Example 3 Example 3 was repeated using the solid composition prepared in Preparation Example 1 instead of solid catalyst component A without the treatment according to the invention. The results are shown in Table 1. Example 4 After storing the slurry of solid catalyst component A prepared in Example 1 at room temperature for 40 days, propylene polymerization was carried out by the method of Example 1. The results are shown in Table 1. Comparative Example 4 The solid composition was treated in the same manner as in Example 1, except that ethyl p-toluate was not used.
After storing the slurry at room temperature for 40 days, propylene polymerization was carried out by the method of Example 1. The results are shown in Table 1. Comparative Example 5 Example 1 was repeated except that the solid composition was not washed with heptane but was carried out in the same manner. The results are shown in Table 1. Comparative Example 6 Example 1 was repeated in the same manner except that in the treatment of the solid composition of Example 1, 0.4 ml of the solid composition slurry, 1.14 mg of triethylaluminum, and 1.64 mg of ethyl p-toluate were used ( Ti concentration during treatment: 9.6 mg/liter). Table 1 shows the results.
Shown below. Example 5 114 mg of triethyl aluminum was added to 198 mg of triisobutyl aluminum, and ethyl p-toluate was added to 198 mg of triisobutyl aluminum.
Example 1 was repeated by substituting 49.2 mg of ethyl benzoate with 45.1 mg of ethyl benzoate. The results are shown in Table 1. Note that the Ti content of the solid catalyst component A obtained by the modification treatment was 4.09%. Example 6 The amount of p-ethyl toluate used during modification treatment
Example 1 was repeated using 82.1 mg. The results are shown in Table 1. The Ti content of solid catalyst component A was 4.05%. Comparative Example 7 Example 1 was repeated with 500 mg of propylene present during the modification treatment. The results are shown in Table 1.

[Table] Analysis of Results A comparison between Example 1 and Comparative Example 1 shows that activity, T- and BD are significantly improved by the modification treatment of the present invention. A comparison between Example 2 and Comparative Example 2 shows that by the modification treatment of the present invention, the catalyst can be sufficiently put to practical use without prepolymerization. A comparison between Example 3 and Comparative Example 3 shows that the persistence of polymerization activity is improved by the modification treatment of the present invention. A comparison between Example 4 and Comparative Example 4 shows that unless an electron donor compound is present during the treatment, the catalyst performance (activity, T-, BD) after the modification treatment deteriorates significantly over time, making it impossible to put it to practical use. I understand that. Comparative Examples 5 and 6 show that the effects of the present invention cannot be achieved unless washing is performed after the modification treatment, and unless the Ti concentration during the modification treatment is 10 mg/liter or more. Comparative Example 7 shows that the effects of the present invention cannot be achieved if olefin coexists during the modification treatment.

[Brief explanation of drawings]

FIG. 1 is intended to assist in understanding the technical content of the present invention regarding Ziegler catalysts.

Claims (1)

[Claims] 1. A method in which propylene is brought into contact with a catalyst system basically consisting of a titanium-containing solid catalyst component (component A) and an organoaluminum compound (component B) for polymerization, in which component A is as follows: A method for producing a propylene polymer, characterized in that: (1) Component A is a solid composition containing magnesium, titanium, and halogen as essential components, in the absence of an olefin, and an organoaluminum compound of the formula H _n R _o AlX _3-(n+o) and the following electron It must be treated with a donor compound and then washed with an inert solvent (in the above formula, R represents a hydrocarbon residue having 1 to 20 carbon atoms, X represents a halogen, m and n is 0≦m<3 and 0, respectively
<n≦3 and 2<m+n≦3); (a) Electron donor compound: a compound selected from carboxylic acid esters and phosphoric acid esters; (2) the above solid composition; The treatment with an organoaluminum compound and an electron donor compound is carried out under the following conditions. (a) Amount of organoaluminum compound/amount of solid composition = 0.1 to 50 (Al/Ti atomic ratio) (b) Amount of electron donor compound/amount of organoaluminum compound = 0.01 to 1.0 (mol/atomic ratio).