JPH03220208A - Production of polypropylene - Google Patents

Abstract

PURPOSE:To obtain a product of high rigidity by performing prepolymerization under specified conditions, adding a nucleator to the polymerization system, and polymerizing propylene in a process for polymerizing propylene in the presence of a catalyst containing a catalyst component prepared by impregnating a magnesium compound with a titanium compound. CONSTITUTION:A process for polymerizing propylene in the presence of a catalyst comprising a catalyst component (A) prepared by impregnating a magnesium compound with a titanium compound, at least one member (B) selected from among organometallic compounds having metals of groups Ia, IIa, IIb, IIIb and IVb of the periodic table and an electron donor (C), wherein at least 0.1g, per g of the component A, of ethylene and/or an alpha-olefin are polymerized, and 0.001-1 pt.wt., per 100 pts.wt. final polymer, nucleator is added to the polymerization system, and the polymerization of the propylene is continued to obtain a highly crystalline polypropylene.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for polymerizing propylene. For more information,
This is a method for producing highly crystalline polypropylene by using a specific nucleating agent in the polymerization system.

[Problems to be Solved by the Invention] Demand for crystalline polypropylene has increased significantly in recent years due to its excellent physical properties.

Coupled with this growth in demand, there have been significant advances in polypropylene manufacturing technology, and in terms of polymerization catalysts, a highly active catalyst with a titanium compound supported on a magnesium compound has been developed, compared to the conventional titanium trichloride type catalyst, and Also, more streamlined bulk polymerization methods and gas phase polymerization methods are being adopted.

However, for some applications, products according to known technology are not fully satisfactory. Adding a nucleating agent is widely used as a method of increasing the rigidity of products. The nucleating agent is blended into the polymer by mixing for the required time using a commonly used Henschel Mixer, Blender, Ribbon Blender, Banbury Mixer, 1 Two-Der Blender, etc., and then granulating it using a normal extruder. However, these methods pose problems such as variations in product physical properties due to poor dispersion of the nucleating agent, and the energy cost consumed in the compounding process is considerable.

In addition, a method has been proposed in which highly rigid polypropylene is produced by a so-called multi-stage polymerization method by devising a polymerization method. For example, JP-A-58-201806, JP-A-58-21
No. 9207, a method for producing a polymer in two stages of a high molecular weight portion and a low molecular weight portion, and JP-A No. 60-490
No. 08, JP-A-60-49009, JP-A-62-12
No. 4108 and JP-A-62-195007,
A method for producing polymers in three steps has been proposed.

However, in these proposals, the catalyst specifically disclosed is a titanium trichloride type catalyst that has been used for a long time, and since the polymerization activity is low, a so-called deashing process is installed to solve problems such as coloring of the product. Is there a need to avoid it?

In any of the methods described above, a nucleating agent is required to achieve even higher rigidity.

Therefore, uniform dispersion of the nucleating agent mentioned above becomes a problem.

[Means for Solving the Problems] As a result of intensive studies to solve the problems of the prior art, the present inventors have developed a highly active and highly stereoregular catalyst in which a titanium compound is supported on a magnesium compound. The present inventors have discovered that a product with high rigidity can be obtained by adding a nucleating agent after polymerizing ethylene and/or α-olefin when propylene is polymerized using this method, and have completed the present invention.

That is, the present invention uses (A) a catalyst component in which a titanium compound is supported on a magnesium compound, and (B) components in elements 1a, Ila, and Ilb of the periodic table.

In polymerizing propylene in the presence of a catalyst consisting of at least one organometallic compound of group mb and IVb metals and an electron-donating compound as component (C), the catalyst component (A
) at least 0.1 g of ethylene per gram; and/
Alternatively, after polymerizing the α-olefin, a nucleating agent is added to the polymerization system at a rate of 0.0 parts by weight per 100 parts by weight of the final polymer obtained.
01 to 1 part by weight, and then polymerization of propylene is continued.

In order to produce highly crystalline polypropylene, it is necessary to use a highly stereoregular catalyst. No. 314210, JP-A-63-317502,
Examples include JP-A-64-105 and JP-A-1-165608. Specific examples include the following catalysts.

(A) (i) at least one member selected from the group consisting of magnesium metal, an organic hydroxide compound, and an oxygen-containing organic compound of magnesium, (i i) an electron-donating compound, and (i i i) an oxygen-containing titanium compound; A homogeneous solution containing an organic compound is reacted with (iv) at least one aluminum halide compound, and the resulting solid product is further reacted with (v) an electron-donating compound and (vi) a titanium halide compound. Examples include the catalyst component (A) obtained by reacting the following.

Examples of the magnesium-containing compound include reactants made of magnesium metal and alcohols such as ethanol and n-butanol, or organic silanols, and oxygen-containing organic compounds of magnesium such as magnesium alkoxides.

Examples of electron-donating compounds include esters such as ethyl acetate, ethyl phthalate, and diisobutyl phthalate, ethers, ketones, and amides. Oxygen-containing organic compounds of titanium include titanium tetraethoxide and titanium tetra-n.
-butoxide, etc. Examples of the aluminum halide compound include ethyl aluminum cyclolide, isobutyl aluminum cyclolide, and the like. Examples of the titanium halide include titanium tetrachloride.

During polymerization, the amount of catalyst component (A) used is 0.001 to 2.5 mmol titanium atoms (IImo
It is preferred to use an amount corresponding to l).

As the organometallic compound of component (B),
At least one selected from organometallic compounds of group a, Ua, Ilb, mb and IVb metals, for example:
n-butyllithium, diethylmagnesium, triethylaluminum, streamy butylaluminum, diethylaluminium chloride, diisobutylaluminum chloride, etc. can be used.

As component (C), electron-donating compounds such as ethyl acetate, butyl propionate, ethyl benzoate, methyl toluate, trimethylmethoxysilane, diphenyldimethoxysilane, and di-butyldimethoxysilane can be used.

The organometallic compound of component (B) is 0 per reactor IL.
．． 02-50 ma+ol, preferably 0.2-5 ■
Use at a concentration of ol.

The electron-donating compound of component (C) is per reactor IL,
0.001-50+mol, preferably 0.01-5m
Use at a concentration of vol.

The manner in which the three components are fed into the polymerization vessel in the present invention is not particularly limited (for example, catalyst component (A), component (B), and component (C) are each fed separately into the polymerization vessel). A method in which catalyst component (A) and component (C) are brought into contact and then brought into contact with component (B) for polymerization. A method of polymerizing by bringing the catalyst component (A), component (B), and component (C) into contact with each other in advance can be employed.

The polymerization of propylene is carried out at a reaction temperature below the melting point of the polymer.
Any of gas phase polymerization, bulk polymerization, and slurry polymerization can be employed. Furthermore, multistage polymerization of two or more stages can also be carried out.

If the polymerization is carried out in the liquid phase, propylene itself may be used as the reaction medium, but it is also possible to use an inert solvent as the reaction medium. The inert solvent can be any commonly used in the art, especially alkanes and cycloalkanes having 4 to 20 carbon atoms.

For example, isobutane, pentane, hexane, cyclohexane, etc. are suitable.

The polymerization reaction conditions are not particularly limited as long as the reaction temperature is lower than the melting point of the polymer, but usually the reaction temperature is 20 to 110 ℃.
℃, pressure 2-50 kg/c sea G.

As the reactor used in the polymerization step, any reactor commonly used in the technical field can be used as appropriate.

For example, using a stirred tank reactor, a fluidized bed reactor, or a circulation reactor, the polymerization operation can be carried out in a continuous mode, a semi-batch mode, or a batch mode.

The nucleating agent used in the present invention is an aliphatic monocarboxylic acid (
Valeric acid, stearic acid, valmitic acid), aliphatic carboxylic acids (succinic acid, glutaric acid, adipic acid), aromatic monocarboxylic acids (benzoic acid, anthranilic acid, cinnamic acid,
acetylsalicylic acid) and aromatic dicarboxylic acids (phthalic acid, etc.), alkali metal salts, alkaline earth metal salts, aluminum salts, titanium salts, chromium salts, etc., and derivatives thereof. Specifically, sodium salt, calcium salt, aluminum salt of pt-butylbenzoic acid, aluminum-bis(pt-butylbenzoic acid) hydroxy, aluminum-bis(p-1 ruyl acid) hydroxy, and aluminum-bis(p-1 ruyl acid) hydroxy. (anisic acid) hydroxy, sodium cyclopentanecarboxylate, sodium glutarate, sodium cinnamate, and the like.

These nucleating agents can be used alone or in combination of two or more. The amount of the nucleating agent added is determined by the amount of the resulting polymer 1.
The range is 0.001 to 1 part by weight per 00 parts by weight. If the amount is less than 0.001 part by weight, the effect of improving the stiffness of the obtained polymer will be small, and if it exceeds 1 part by weight, the effective effect of improving the nucleating agent will be small.

The preferred amount added is 0.005 to 0.5 parts by weight.

As for the method of adding the nucleating agent, the nucleating agent may be added to the polymerization system as it is, or the nucleating agent may be suspended or dissolved in an inert organic solvent and then added.

The nucleating agent can be added at any time as long as 0.1 g of polymer is produced per 1 g of catalyst component (A), but it is preferable to add it by the time 80% of the final polymer is produced. . Therefore, per gram of catalyst component (A).
It is preferable to add it at an appropriate stage after prepolymerizing 1 g to 100 g of the polymer and before starting the final polymerization stage in multistage polymerization. Moreover, when producing 0.1 g to 100 g of polymer per 1 g of catalyst component (A), prepolymerization well known in the art can be employed.

In this case, when adjusting the catalyst component (A), (1) to (v
In addition to each component i), it is preferred to use a surfactant. The surfactants used include anionic surfactants, cationic surfactants, nonionic surfactants,
Examples include amphoteric surfactants and fluorosurfactants. Among them, nonionic surfactants are most preferred. For example, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, sorbitan monolaurate,
Examples include sorbitan distearate.

The monomers used in the prepolymerization are ethylene, - of the formula R-CH-CI (2, where R is a straight-chain or branched substituted compound having from 1 to 10 carbon atoms, in particular from 1 to 8 gJ).・Representing an unsubstituted alkyl group) α-olefins include propylene, butene-1,4-methylpentene-1, octene-1, etc.If two or more of these monomers are used, Good too.

As a method of multistage polymerization, Japanese Patent Application No. 1-145285,
Patent application No. 1-196552 can be mentioned. For example, in the step of polymerizing a high molecular weight component, the intrinsic viscosity [η]H is 1.5 to 5.5, preferably 2.0 or more, 5
．． Production ratio R of polypropylene of 0 or less, 4 is 20 to 8
0% by weight, preferably 30 to 70% by weight, and in the step of polymerizing low molecular weight components, the intrinsic viscosity [η
．． The production ratio RL of polypropylene of 4 to 2.5, preferably 0.6 to 2.0 is 20 to 80% by weight, preferably 3
0 to 70% by weight. Intrinsic viscosity of the final polymer [η
is between the intrinsic viscosity and polymerization ratio of each component in the two steps selected from the above range ([77] HXR)! + [
77] L XRt, )/100- [η] w
(1), and further satisfies the relationship 1≦([η]H−[η]L)/RH≦10(2), and the xylene soluble content and the limiting viscosity [η] is X ≦-0,3X [η]+3.0... (3)
This is a multi-stage polymerization method that satisfies the following. At this time, the order of production of each polypropylene produced in two steps is arbitrary, but it is preferable to carry out the polymerization using two or more polymerization vessels arranged in series.

Alternatively, in the step of polymerizing the high molecular weight component, the production ratio R3 of polypropylene having an intrinsic viscosity [η]3 of 3 or more, preferably 3.5 or more and 8 or less is 10 to 50% by weight,
Preferably it is 15 to 40% by weight, and in the step of polymerizing the intermediate molecular weight component, the production ratio R of polypropylene having an intrinsic viscosity [η]2 of 1 to 3, preferably 1.3 to 2.7.
2 is set at 10 to 70% by weight, preferably 15 to 50% by weight, and in the step of polymerizing the low molecular weight component, the intrinsic viscosity [η] is set at 0.2 to 1.0, preferably 0.4 to 0.9
The production ratio R1 of polypropylene is 10 to 80% by weight,
Preferably it is 20 to 60% by weight. The intrinsic viscosity [η] of the final polymer is determined by the relationship between the intrinsic viscosity of each component in the three steps selected from the above range and the polymerization ratio ([η] , xR, + [77] 2 XR2+ [7
7] 3 XR3)/100- [η] w
The relationship (4) is satisfied, the intrinsic viscosity [η] is I~4, and the xylene soluble content X of polypropylene obtained in each of the three steps and the intrinsic viscosity [η] are Y η]+3.0...This is a multi-stage polymerization method that satisfies (5). At this time, although the order of production of each polypropylene produced in three steps is arbitrary, it is preferable to polymerize using three or more polymerization vessels arranged in series.

[Effects of the Invention] By using the method of the present invention, polypropylene having excellent rigidity and good workability can be obtained. That is, by using a catalyst component formed by supporting a titanium compound on a magnesium compound and adding a nucleating agent after polymerizing at least 0.1 g of ethylene and/or α-olefin per 1 g of the catalyst component, the nucleating agent is added. Dispersibility is improved and highly rigid polypropylene can be easily obtained. Furthermore, it is also possible to omit the blending step compared to conventional methods.

The present invention is not limited in any way by these examples.

The properties of the polymers in Examples, Reference Examples, and Comparative Examples were measured by the following methods.

MI: Melt index according to ASTM D-1238 condition E Intrinsic viscosity [η]: Measured in orthodichlorobenzene at 140°C, but the intrinsic viscosity [η and viscosity average molecular weight M
There is the following formula between v.

-40,725 [η] =1.88X10 xMv Flexural modulus:
Flexural modulus according to J I 5K7203.

Add 4g of two samples of xylene soluble content (X) to 200ml of xylene.
After dissolving in the solution, leave it in a constant temperature bath at 25°C for 1 hour. The precipitated polypropylene is filtered and the filtrate is collected. After most of the xylene in the filtrate has been evaporated, the filtrate is further vacuum dried to recover the xylene-soluble content, which is calculated as a percentage of the weight of the original sample.

[Example] The present invention will be illustrated below with reference to Example 1. (a) [Preparation of catalyst component' (A)] In a 2 L autoclave equipped with a stirring device, 12 g of metallic magnesium powder (0 , 49 mol), and to this add 0.6 g of iodine and 334.3 mol of 2-ethylhexanol.
g (2,6 mol) and titanium tetrabutoxide 168. 0 g (0,49 Ilol).

Diisobutyl phthalate 27.6g (0,099mol
) was added thereto, and decane IL was added thereto, then the temperature was raised to 90° C., and the mixture was stirred for 1 hour under a nitrogen blanket while excluding generated hydrogen gas. Subsequently, the temperature was raised to 140°C and the reaction was carried out for 1 hour to form a homogeneous solution containing magnesium and titanium (M
g-Ti solution) was obtained.

Mg in Mg-Ti solution in a flask with an internal volume of 500 ml.
After adding 0.048 mol in terms of conversion and rapidly cooling to -20°C, a solution prepared by diluting 14.9 g of i-butylaluminum dichloride to 50% with decane was added over 2 hours. After everything was added and the temperature was raised to room temperature, a slurry containing a white solid product was obtained. After the slurry containing the white solid product thus obtained was heated to 60° C., 11000 pp of sorbitan distearate was added. Then diisobutyl phthalate3. 3g (0,012mol
), then the entire amount of a solution prepared by diluting 47 ml of titanium tetrachloride with 47 ml of 1,2-dichloroethane was added, and the mixture was reacted for 4 hours. At this time, no aggregation of the solid product was observed. Stirring was further performed at 70°C for 1 hour.

The solid part was collected by filtering the product and again
47ml of titanium tetrachloride and 47ml of 1,2-dichloroethane
1 and stirred at 70°C for 1 hour.

Hexane was added to the product and the product was thoroughly washed until no titanium compound released was detected.

In this way, a slurry of catalyst component (A) suspended in hexane was obtained. The supernatant liquid was removed and dried under a nitrogen atmosphere, and elemental analysis revealed that Ti was 3.0% by weight.

Reference Example 2 (a) Prepolymerization of Catalyst Component (A) Catalyst Component (A) obtained by the method of Reference Example 1 above by purging the interior of a stainless steel electromagnetic stirring autoclave with an internal volume of 5 L with sufficient nitrogen 52 g+ Organometallic compounds (
B) as triethylaluminum 326 v+aol
, 81.4 mmol of diphenyldimethoxysilane as an electron-donating compound (C) was sequentially added, and 3 L of hexane was added. Thereafter, sorbitan distearate was added to the total content at 1400 pptn. After adjusting the autoclave internal pressure to 0-1 kg/cJG and internal temperature to 20°C, stirring was started, and while maintaining the temperature at 20°C, 52 g of propylene was supplied over 20 minutes, followed by stirring for 30 minutes. Subsequently, solid components were separated by filtration and thoroughly washed with hexane to obtain a slurry of prepolymerized catalyst components suspended in hexane. After removing the supernatant and drying under a nitrogen atmosphere, the yield was 104 g. Therefore, 1 g of propylene was polymerized per 1 g of catalyst component (A).

Example 1 The inside of a fJ5L stainless steel electromagnetic stirring autoclave was sufficiently purged with nitrogen, and 878 mmol of triethylaluminum Q was added as component (B).

0.43 diphenyldimethoxysilane as component (C)
8 + mol and the prepolymerized catalyst component obtained in Reference Example 2 as the catalyst component (A) in an amount of 0.012 mmol in terms of Ti.
aluminum-bis(p-t-butylbenzoic acid) hydroxy (hereinafter referred to as
0.53 g of ABBH) was added. Adjust the autoclave internal pressure to 0.1 kg/cd G, and add 0.1 kg of hydrogen.
/c- added and started stirring (600 rpm), then 80
℃ and added 2.5 L of propylene. Propylene was polymerized at the same temperature for 90 minutes. After the polymerization reaction was completed, stirring was stopped, unreacted propylene in the system was released, and the resulting polymer was recovered. As a result, the produced polymer was 11 Log. Activity per catalyst component (A) is 55500g/
Corresponds to g. When 700 ppm of Irganox B-220 (manufactured by Ciba Geigy) was added to the polymer and granulated using a 25 mm extruder, the MFR was 2.6 g/10 minutes.

Moreover, the xylene soluble content of the polymer was 1.3%.

Examples 2 to 3, Comparison 91J1.2 Same as Example 1 except that the prepolymerized catalyst component obtained in Reference Example 2 was used and the amount of ABBH suspended in hexane was changed as shown in Table 1. Polymerization was carried out in the same manner. In comparative example 1,
The prepolymerization catalyst component was the catalyst component (A) obtained in Reference Example 1.
Polymerization was carried out in the same manner as in Example 1 except that the following was changed. Comparative example 2
Then, polymerization was carried out in the same manner as in Example 1 except that ABBH was not added. The results are shown in Table-1.

Example 4 The interior of a stainless steel electromagnetic stirring autoclave with an internal volume of 5 L was sufficiently purged with nitrogen, and 1.82 mn+o1. of triethylaluminum was added as the catalyst component (B). Ingredient (C)
0.91 mwol of diphenyldimethoxysilane and the catalyst component (A) obtained in Reference Example 1 were 0.91 mwol in terms of Ti.
026-mol were added sequentially. Adjust the autoclave internal pressure to 0-1 kg/cd G and stir (600
rpm), 0.03 kg/cd of hydrogen was added, the temperature was raised to 80°C, and 265 L of propylene was added. 3 at the same temperature
Propylene was polymerized for 0 minutes. After depressurizing, 0.53 g of ABBH suspended in hexane was added, the internal pressure of the autoclave was adjusted to 0.1 kg/cd G, 4.0 kg/cd of hydrogen was added, the temperature was raised to 80°C, and propylene was heated to 2.0 kg/cd.
5L was added, and propylene was polymerized at the same temperature for 11 minutes.

After the polymerization reaction was completed, stirring was stopped, unreacted propylene in the system was simultaneously discharged, and the produced polymer was recovered. the result,
The amount of produced polymer was 1110 g. The activity per catalyst component (A) was equivalent to 26,400 g/g, and the xylene soluble content of the polymer was 1.5%. When the polymer was granulated using a 25 mm extruder in the same manner as in Example 1, 99 g of VFRl was obtained.
/10 minutes, and the intrinsic viscosity [η] was 1.84. Also,
Estimating from the polymerization conditions, the intrinsic viscosity [η] of the polymer obtained in the first stage is 3. The intrinsic viscosity [η] of the polymer obtained in the second stage is 0.7, and the intrinsic viscosity [η] of the polymer obtained in the second stage is 0.7. Since the limiting viscosity [η] is 1.84, the production ratio between the first stage and the second stage is estimated to be 50,150. The results are shown in Table-1.

Example 5 A two-stage polymerization of propylene was carried out in the same manner as in Example 4. However, the amount of ABBH added was changed to 2.12 g. As a result, the second stage polymerization time was 35 minutes, and the produced polymer was 116
0 g, and the xylene soluble content of the polymer was 1.5%. The activity per catalyst component (A) corresponds to 29,700 g/g. When the polymer was granulated using a 25 mm extruder in the same manner as in Example 1, MFRl, 4 g/10 min, and intrinsic viscosity [
η] was 1.96. The generation ratio between the first and second stages is estimated to be 55/45. The results are shown in Table-1.

Example 6 A two-stage polymerization of propylene was carried out in the same manner as in Example 4. However, sodium benzoate (N
ABA) was added.

As a result, the second stage polymerization time was 35 minutes, and the produced polymer was 1
090g, 1, and the xylene soluble content of the polymer is 1.59
It was 6. Activity per catalyst component (A) is 26,700
Corresponds to g/g. As in Example 1, the polymer was 25 mm thick.
When granulated using an extruder, the MFR was 3.2 g/10 min, and the intrinsic viscosity [η] was 1.96. The generation ratio between the first and second stages is estimated to be 55/45. The results are shown in Table-1.

Example 7 In the same manner as in Example 4, 1.0% triethylaluminum was placed in an autoclave. 32m*o1. Polymerization was started by sequentially adding 0.657 mIIol of diphenyldimethoxysilane and the catalyst component (A) obtained in Reference Example 1 at 0.0188 ssol in terms of Ti. In the first stage, propylene was polymerized at 80°C for 20 minutes. After depressurizing, add 0.53g of ABBH suspended in hexane to bring the internal pressure of the autoclave to 0.
,,adjust to 1 kg/cd G, hydrogen to 0.5k
g/c-, heat to 80°C, add 2.5L of propylene,
Propylene was polymerized at the same temperature for 18 minutes. After depressurizing, the autoclave internal pressure was adjusted to 0.1 kg/c+&G, hydrogen was added at 4.0 kg/c-, the temperature was raised to 80°C, 2.5 L of propylene was added, and propylene was polymerized at the same temperature for 11 minutes. After the polymerization reaction was completed, stirring was stopped, unreacted propylene in the system was simultaneously discharged, and the produced polymer was recovered. As a result, the amount of produced polymer was 1180 g, and the xylene soluble content of the polymer was 1.6%. The activity per catalyst component (A) corresponds to 28200 g/g. When the heavy body was granulated using a 25 mm extruder in the same manner as in Example 1, the MFR was 3.5 g/10 min, and the intrinsic viscosity [η] was 1.79.
Met. Also, estimated from the polymerization conditions, the intrinsic viscosity [η] of the polymer obtained in the first stage is 4. The intrinsic viscosity [η] of the polymer obtained in the second stage is 265. The intrinsic viscosity [η] of the obtained polymer is 0.7, and the production ratios of the first, second, and third stages are estimated to be 15/45/40.

The results are shown in Table-1.

Example 8 A three-stage polymerization of propylene was carried out in the same manner as in Example 4. Then, ABB) was added after the second stage polymerization was completed. As a result, the amount of produced polymer was 1070 g, and the xylene soluble content of the polymer was 1.5%. When the polymer was granulated using a 25 mm extruder in the same manner as in Example 1, the MFR was 3.1 g.
/10 minutes, the intrinsic viscosity [η] is 1.82, and the first stage is
The generation ratio of the second and third stages is estimated to be 15/45/40. The results are shown in Table-1.

Comparative Example 2.3 In Comparative Example 2, polymerization was carried out in the same manner as in Example 1 except that ABBH was not added. In Comparative Example 3, two-stage polymerization of propylene was carried out in the same manner as in Example 4, but ABBH was not added before the start of the second-stage polymerization. 700 ppm of Irganox B-220 was added to the polymer obtained in Comparative Example 2.3.
, ABBH was added in an amount of 500 ppm, and the polymer was granulated using a 25 mm extruder in the same manner as in Example 1. In Comparative Example 2, MFRl was 5 g/10 min, and in Comparative Example 3, MFRl
, 4 g/10 minutes, and the intrinsic viscosity [η] was 1.97.

The generation ratio between the first and second stages of Comparative Example 3 is estimated to be 55/45. The results are shown in Table 1, and are shown in Example 1,
The flexural modulus is lower than 4.

Claims (1)

[Claims] (1) (A) Catalyst component formed by supporting a titanium compound on a magnesium compound (B) As a component, Ia, IIa, IIb, and II of the periodic table are used.
In polymerizing propylene in the presence of a catalyst consisting of at least one organometallic compound of group Ib and IVb metals and an electron-donating compound as component (C), the catalyst component (A
) at least 0.1 g of ethylene per gram; and/
Alternatively, after polymerizing the α-olefin, a nucleating agent is added to the polymerization system at a rate of 0.0 parts by weight per 100 parts by weight of the final polymer obtained.
1. A method for producing highly crystalline polypropylene, which comprises adding propylene in an amount of 0.01 to 1 part by weight, and then continuing polymerization of propylene.