JPS646212B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an industrially advantageous method for producing high quality propylene copolymers. More specifically, we aim to make propylene copolymers with an excellent balance of qualities required for propylene copolymer films, such as transparency, heat sealability, rigidity, cold resistance, slipperiness, and blocking properties, industrially and economically advantageous. Relating to a method of manufacturing. Isotactic polypropylene produced with stereoregular catalysts has excellent rigidity, strength, moldability, appearance of molded products, and heat resistance, and is therefore widely used in various molded products. Furthermore, polypropylene films are highly valued for their transparency and stiffness, and are widely used as various packaging materials. One of the drawbacks of polypropylene is that its impact strength is highly dependent on temperature, and its impact strength rapidly decreases from room temperature to 0°C, that is, it has poor cold resistance. Another drawback is that the heat-sealing temperature of the film and the shrinkage temperature of the stretched film are too high. For example, if you try to heat-seal a biaxially stretched film at a temperature that provides sufficient heat-sealing strength, heat shrinkage will occur. Heat sealing is virtually impossible because the appearance of the film is impaired. In order to improve these drawbacks of polypropylene, random copolymers such as propylene-ethylene, propylene-butene-1, propylene-ethylene-butene-1, etc., which are copolymerized with small amounts of α-olefins such as ethylene and butene-1, have been produced. It is used alone or blended with other resins or rubbers as a heat-sealing layer for biaxially oriented polypropylene films, shrink wrapping films, cold-resistant polypropylene films, etc. The method for producing these propylene copolymers is as follows:
Slurry polymerization (hereinafter referred to as solvent polymerization) using an inert solvent such as hexane or heptane is common, but in solvent polymerization, many worthless amorphous polymers are dissolved in the solvent, resulting in loss of monomers. This is not only economically disadvantageous, but also tends to cause problems in production, such as an increase in stirring power due to an increase in slurry viscosity and a decrease in heat transfer in the polymerization tank. This phenomenon becomes more serious as attempts are made to produce copolymers with high comonomer (ethylene, butene-1, etc.) contents that have excellent cold resistance and heat sealability. If the propylene copolymer is polymerized in the monomer itself or in an inert solvent with low solubility such as propane or butane (hereinafter referred to as bulk polymerization), less amorphous polymer will be dissolved in the solvent, making it economically viable. It is also advantageous in terms of operation, and the problems in the solvent polymerization method described above are significantly alleviated. Furthermore, as an advantage of the bulk polymerization method, the polymerization rate is generally higher than that of the solvent polymerization method, especially when the monomer itself is polymerized as a solvent, and it can be operated under conditions with good catalyst efficiency. It is possible to reduce the amount of residue, especially of solid catalyst components such as titanium trichloride. In addition, compared to general solvent polymerization methods that use hexane, heptane, etc. as solvents, bulk polymerization methods use easily vaporized monomers themselves, propane, butane, etc. as solvents, so only a simple step of reducing the pressure of the polymerization slurry is required. Therefore, it also has the great advantage that the copolymer can be separated from the solvent. However, if the polymerization slurry is directly depressurized to separate the solvent by vaporization, catalyst residues (mainly organic aluminum compounds) and amorphous polymers dissolved in the polymerization slurry remain on the surface of the powder copolymer, causing various problems. cause. First, a large amount of residual catalyst residue causes foaming, coloring, and corrosion of the copolymer, making it impossible to use it for high-quality applications. Secondly, the copolymer powder with the amorphous polymer remaining on the surface becomes very sticky, making subsequent handling difficult. Especially for copolymers with high copolymer content, the powders stick together and form blocks.
This can even cause situations such as pipe blockage. Third, since the entire amount of amorphous polymer produced in the polymerization tank is recovered together with the powder copolymer, quality problems originating from the amorphous polymer become noticeable.
That is, when it is made into a film, its slipperiness, blocking properties, and transparency deteriorate. In order to overcome the disadvantages of the bulk polymerization method while taking advantage of its advantages, a method has been proposed in which the polymer slurry produced by the bulk polymerization method is brought into contact with liquid phase propylene in a countercurrent washing tower in a countercurrent manner (in particular, 1977
−98588, etc.). Even if washing is performed with propane, butane, etc., the advantages of the bulk polymerization method are not lost. In other words, this method is economically and industrially advantageous compared to general solvent polymerization methods, and is also an excellent method that overcomes the drawbacks of simple bulk polymerization methods. Copolymers, especially copolymers with a relatively high ethylene content, have excellent heat sealability and cold resistance when made into films, but they have poor transparency, stiffness, slipperiness,
It has the disadvantage of insufficient blocking properties. On the other hand, the copolymer of propylene and α-olefin such as butene-1 produced by this method has excellent heat-sealing properties and stiffness, and has relatively good transparency, slipperiness, and blocking properties; The impact strength, that is, the cold resistance is poor. Conventionally, the ratio of titanium trichloride and organic aluminium compounds such as triethylaluminum and diethylaluminum chloride, which are commonly used in the industrial production of polypropylene, is 1:1 to 1.
20 (see page 26 of "Polypropylene Resin" published by Nikkan Kogyo Shimbun). This can be found in various publications (e.g. L. Reich and Interscience Publishers).
Polymerization by A. Schindler
Organometallic Compounds Chapter D
Kinetics of Ziegler by T. Keii published by Kodansha
Natta Polymerization Chapter 4.2, etc. and their cited references) or JP-A-47-34478, the Al/Ti molar ratio of the catalyst component is 1.
The smaller the catalyst activity and the stereoregularity (n
-represented by the amount of heptane-insoluble parts and the degree of crystallinity), and when the Al/Ti molar ratio exceeds about 10, the catalytic activity and stereoregularity decrease. In the production of propylene, ethylene, and α-olefin copolymers, for example, in the specification of JP-A-49-35487, the B/A molar ratio of the titanium compound (A) and the organoaluminum compound (B) is There is a description that it is about 0.5 to 20, preferably 1 to 10, and it was common knowledge to practice within the same range. However, in order to produce a high quality propylene copolymer, which is the object of the present invention, conventional methods have had many problems as already mentioned. As a result of various studies to solve the above-mentioned drawbacks of the bulk polymerization method, the present inventors used a specific Ziegler-Natsuta catalyst in a range of component ratios unimaginable based on conventional knowledge, and in a specific solvent. By copolymerizing propylene, ethylene, and butene-1, and washing the polymer slurry in a countercurrent manner with a specific solvent, heat sealability and cold resistance are achieved without sacrificing the economic and industrial advantages of the bulk polymerization method. The present inventors have discovered that a propylene copolymer can be obtained that highly satisfies various physical properties required when it is made into a film, such as transparency, slipperiness, and blocking property, leading to the present invention. That is, the present invention consists of (a) titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound and further activated, and (b) an organoaluminum compound, and the molar ratio of (a) and (b) is (b)/ Using a catalyst system with (a) between 20 and 100 and a solubility parameter of 7.0
(cal/cc) The polymerization slurry extracted by copolymerizing propylene, ethylene, and butene-1 in a liquid phase medium of ^1/2 or less was introduced into the upper part of the countercurrent washing tower, and the solubility parameter was supplied from the lower part. is 7.0
(cal/cc) The ethylene content is ^1/2 or less and is cleaned by contacting with a liquid phase medium in countercurrent.
This is a method for producing an ethylene, propylene, butene-1 copolymer having a propylene content of 80 to 99 weight% and a butene-1 content of 0.5 to 15 weight%. The titanium compound used as the catalyst component (a) in the present invention is β-type titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound.
It is characterized by using a catalyst that is used as a starting material for producing an activated titanium compound and is highly activated by treatment with a complexing agent, treatment with an organoaluminum compound, treatment with titanium tetrachloride, or a combination thereof. This catalyst can be prepared by simply heating β-type titanium trichloride using known methods such as heat treatment (for example,
The activity is at least three times higher than that obtained by the method described in Publication No. 20501). More specifically, for example, the method discovered by the present inventors (Japanese Unexamined Patent Publication No. 74595/1983, Japanese Patent Application No. 51/1983)
108276) can be used. In addition, when carrying out the present invention, Japanese Patent Application Laid-Open No. 47-34478
A highly active catalyst obtained by the method described in the above publication, that is, by treating β-type titanium trichloride with a complexing agent such as ether and then treating it with titanium tetrachloride, can also be used satisfactorily in this method. Catalysts other than those essential to the present invention, such as currently commercially available titanium tetrachloride, are reduced with metallic aluminum and activated by pulverization (for example, titanium trichloride AA manufactured by Stouffer).
The effects of the present invention cannot be achieved with conventionally known catalysts prepared by reducing titanium tetrachloride or titanium tetrachloride with an organoaluminum compound and heat-treating it. Specific examples of the organoaluminum compound used as the catalyst component (b) in the present invention include trialkylaluminum, alkylaluminum halide, alkylaluminum hydride, alkylaluminum alkoxide, alkylaluminum, alkoxyhalide, etc. Alkylaluminum halide is preferred. Preferred compounds among these are dimethylaluminum chloride, diethylaluminium chloride, diisobutylaluminum chloride, diethylaluminium bromide, diethylaluminium iodide, ethylaluminum sesquiclide, mixture of triethylaluminum and diethylaluminium, and mixture of triethylaluminum and aluminum chloride. etc., and diethylaluminum chloride is particularly preferred. In the present invention, the molar ratio of catalyst components (a) and (b) (b)/
(a) is important, 20-100, preferably 30-70
If a catalyst is not used within this range, neither the worthless amorphous polymer that dissolves in the polymerization medium nor the low molecular weight amorphous polymer contained in the copolymer will be reduced, and the effects of the present invention will be achieved. What cannot be done is as shown later in Examples and Comparative Examples. In the present invention, the catalyst essentially contains the two components in the above-mentioned specific ratio, but may further contain a known electron-donating compound as a third component. Such third components are generally compounds containing oxygen, nitrogen, sulfur, or phosphorus atoms, but aromatic compounds are also well known. Specific examples include ethyl acetate, methyl methacrylate,
Saturated or unsaturated aliphatic, alicyclic, and aromatic esters such as ethyl benzoate and ε-caprolactone, ethers such as dibutyl ether and tetrahydrofuran, organic sulfur-containing compounds such as butyl thioether and thiophenol, and triethylamine. Amines, organic phosphorus compounds such as tri-n-butylphosphine, triphenylphosphite, tri-n-butylphosphite, tri-n-butylphosphate, hexamethylphosphoramide, benzene, toluene, azulene, etc. These include aromatic compounds. Two or more of these may be used simultaneously. The ratio of the electron-donating compound to the above-mentioned two catalyst components varies depending on the type of electron-donating compound, so it should be determined by balancing the allowable degree of reduction in catalyst activity with the amount of atactic polymer generated. Although there are appropriate ranges for each, the molar ratio relative to the catalyst component (a) is generally about 0.01 to 100. The method of charging a catalyst consisting of catalyst components (a), (b) or (a), (b) and an electron-donating compound into a polymerization vessel is as follows:
These may be added separately, or a possible combination of two or three components may be mixed and added. The composition of the copolymer to which the method of the present invention is applied is:
The content of propylene is 80-99% by weight, the content of ethylene is 0.5-5% by weight, and the content of butene-1 is
The content of propylene is preferably 86-98% by weight, the content of ethylene is 1-4% by weight, and the content of butene-1 is 1-10% by weight.
If the content of propylene is higher than this, the heat sealability and cold resistance of the film will be insufficient, and the effects of the present invention will not be significant. On the other hand, if the propylene content is smaller than this, it will be difficult to manufacture and the stiffness, transparency, slipperiness and blocking properties will deteriorate. The ratio of ethylene content to butene-1 content in the copolymer is 1:30 to 10:1, preferably 1:10 to
The ratio is 4:1. Ethylene content greater than this ratio results in lower stiffness, transparency, slipperiness, and
On the other hand, if the butene-1 content is higher than this ratio, the propylene-butene-1 content is poor.
1 copolymers, they have poor cold resistance. The ratio of each monomer supplied to the polymerization system is determined so as to obtain a copolymer with the desired composition, taking into account the monomer reactivity ratio determined by the manufacturing conditions (temperature, pressure, type of polymerization medium, catalyst, etc.) choose. The liquid phase medium used in the polymerization system and the liquid phase medium supplied from the bottom of the countercurrent washing tower have a solubility parameter δ (according to the JHHildebrand definition) of 7.0.
(cal/cc) ^1/2 or less. Specific examples of such liquid phase media include n-propane, n-butane, isobutane, isopentane, propylene, 1-butene, 2-cis and trans-butene, isobutylene, etc., and mixtures thereof. Also, even if a mixture of these and a small amount of a solvent with a large δ such as hexane, heptane, or toluene is used, the δ of the mixture
It can be used if it is less than 7.0 (cal/cc) ^1/2 . The liquid phase medium used in the polymerization system and the liquid phase medium supplied from the lower part of the countercurrent washing tower may be the same or different in type or mixture composition. The liquid phase medium used is preferably the monomer itself, essentially free of inert solvents, ie propylene and/or butene-1. Molecular weight adjustment can be carried out using various molecular weight modifiers, but the use of hydrogen is common. The polymerization conditions in the present invention include the characteristics of the polymerization system (for example, polymerization rate, polymerization time, residence time, etc.) and the characteristics of the obtained copolymer (composition, melt viscosity, Refers to conditions that are appropriately selected by comparing the pressure, temperature, catalyst system, concentration of molecular weight regulators, stabilizers, etc. of the polymerization system, as well as stirring conditions, cooling and heating conditions, etc. after comparing the cold xylene soluble parts, etc. . The polymerization temperature is 30-100°C, preferably 40-80°C. The average residence time or polymerization time in the polymerization vessel is arbitrary, but in order to avoid complicated post-treatment steps, it should be given so that 8000 parts by weight or more of copolymer is produced per 1 part by weight of catalyst component (a). It is desirable to choose the polymerization time or average residence time under other polymerization conditions. FIG. 1 illustrates an example of the steps of the method of the present invention. The method of the present invention will be explained below with reference to FIG. Into the polymerization tank, liquid phase propylene, ethylene, and butene-1 were passed through lines, respectively.
A molecular weight regulator such as hydrogen is fed through a line, and a catalyst is fed through a line. When using inert solvents such as propane and butane,
It is fed through a separate line or as a mixture with liquid propylene. The polymerization reaction is carried out at a temperature of 30 to 100℃, preferably 40 to 80℃.
C. and proceed under pressure capable of keeping the monomer mixture, or the mixture of monomers and an inert solvent such as propane, butane, in liquid form. The produced polymerization slurry is extracted batchwise, preferably continuously, from the polymerization tank through a valve and supplied to the upper part of a countercurrent washing tower (hereinafter abbreviated as upper feed). A liquid phase medium containing no polymers soluble in the polymerization slurry (mainly amorphous polymers) and having a δ of 7.0 (cal/cc) ^1/2 or less is supplied to the washing tower from the lower part through a line (hereinafter referred to as the lower part). (abbreviated as feed). The polymer soluble in the polymerization slurry and the catalyst remaining in the polymerization slurry are selectively discharged through an upper overflow line and introduced into an amorphous polymer recovery system. The polymerization slurry comes into contact with the liquid phase medium from the lower feed in the washing tower in a countercurrent manner, and the polymer insoluble in the polymerization slurry is selectively extracted from the lower line, reducing the level (or concentration) of the slurry accumulated at the bottom of the tower. ) The pressure is reduced to near normal pressure by a valve connected to the regulator LC and enters the flash tank. Monomers that are volatile at normal pressure are vaporized in a flash tank and discharged from the line to be sent to the refining process. On the other hand, the polymer separated in the flash tank is sent to a hopper or granulator through a valve, either as it is or, if necessary, after a post-processing operation such as a catalyst decomposition step. The functions of the countercurrent washing tower in the method of the present invention are, firstly, to separate the liquid medium in the upper feed and extract it from the overflow line at the top of the tower together with the lower feed liquid that has risen from the bottom of the tower; The insoluble polymer in the upper feed liquid is washed with the lower feed liquid and is discharged from the bottom of the column along with a portion of the lower feed liquid. As the structure of the countercurrent washing tower, the structure shown in Japanese Patent Application Laid-Open No. 139886/1986 is preferably used in order to satisfy the above-mentioned conditions. In order to explain the method of the present invention more clearly, comparative examples and examples are described below, but the present invention is not limited only by these examples.
Note that the characteristic values in the following examples were measured by the following method. (1) Melt index (MI) Based on JIS K6758. (2) Heat sealing temperature A sample with a width of 25 mm obtained by pressing films together using a heat sealer at a specified temperature for 2 seconds under a load of 2 kg/cm ² was peeled at a peeling speed of 200 mm/min and a peeling angle of 180°. The peel resistance obtained by doing this is 300
The temperature when g/25 mm was taken as the heat sealing temperature. (3) Transparency (haze) Based on ASTM D1003. (4) Opening properties (blocking) Blocking test pieces were measured by blocking at 60° C. for 3 hours under a load of 40 g/cm ² using a blocking tester manufactured by Shimadzu Corporation. (5) Stiffness Based on ASTM D747. (6) Cold resistance At 0°C, a 40mmφ test piece was fixed horizontally, and darts of various weights (the impact surface was a hemisphere with a radius of 1/2 inch) were dropped naturally from a certain height onto the center of the specimen. The kinetic energy of the dart when 50% of the test piece breaks was determined from measurements of a large number of test pieces, and the value obtained by dividing that energy by the thickness of the test piece was used as a measure of low-temperature impact strength, that is, cold resistance. Haze, heat-sealing temperature, blocking, and cold resistance are determined by pelletizing a powder copolymer containing antioxidants, anti-blocking agents, and lubricants using a granulator, and forming a film with a thickness of 30 microns using a T-die molding machine. Measurements were made on the film. Example 1 (1) Preparation of catalyst 1 Preparation method (preparation of reduction product) After purging a 200mm reaction vessel with argon, 40% of dry hexane and 10% of titanium tetrachloride were added, and the solution was kept at -5°C and dried. A solution consisting of 30% hexane and 23.2% ethylaluminum sesquichloride was added dropwise under conditions such that the temperature of the reaction system was maintained at -3°C or lower. Stirring was then continued at the same temperature for 2 hours. After the reaction, the resulting reduction product was separated into solid and liquid at 0°C and washed twice with 40% hexane.
16Kg of reduction product was obtained. 2. Preparation method The reduction product obtained in the preparation method was slurried in n-decalin, and the slurry was heat-treated at 140° C. for 2 hours at a slurry concentration of 0.2 g/cc. After the reaction, the supernatant was extracted and washed twice with 40 ml of hexane to obtain a titanium trichloride composition (A). 3 Preparation method Titanium trichloride composition prepared according to the preparation method
(A) 11Kg was slurried in toluene 55% to form a titanium trichloride composition (A)/,/diisocyamyl ether=
Iodine and isoamyl ether were added at a molar ratio of 1/0.1/1.0, and the mixture was reacted at 80°C for 1 hour to obtain a titanium trichloride solid catalyst (B). (2) Production of ethylene-propylene-butene-1 copolymer In a 30 m ³ polymerization tank, add 900 kg/hr of liquid propylene, 11 kg/hr of ethylene, 180 kg/hr of butene, and 40 g (0.26 mol) of the above solid catalyst (B). /hr, diethylaluminium chloride (DEAC) 1100g (9.1mol)/hr, methyl methacrylate 40g (0.40mol)/hr are continuously supplied in the presence of hydrogen, the inside of the tank is kept at 60℃, and ethylene, propylene The copolymerization reaction of and butene-1 was carried out in a flow system. The polymerization slurry was continuously extracted from the bottom of the polymerization tank so that the liquid level in the tank was kept constant, and was supplied to the top of the countercurrent multistage contact washing tower shown in FIG. Isobutanol (1 kg/hr) was fed as a deactivator from the center of the washing tower. On the other hand, purified liquid phase propylene maintained at 50 to 52°C was continuously supplied from the bottom of the column at a flow rate of 1100 kg/hr, and the inside of the column was stirred at a very slow speed of 12 rpm. A level meter measures the insoluble copolymer deposited at the bottom of the tower.
The water was continuously extracted from the run to the flash tank through a pressure reducing valve linked to the LC. Thus, 450 kg/hr of powder copolymer was obtained. On the other hand, liquid phase monomers containing substances soluble in liquid phase monomers such as the reaction product of the catalyst and isobutanol and soluble amorphous polymers were discharged from the top of the column and introduced into the atactic polymer recovery equipment. .
In this way, 7.3 kg/hr of amorphous polymer was recovered, but the loss of the finely divided solid copolymer contained therein was less than 1%. The recovery ratio of atactic polymer (AP recovery ratio) to the total copolymer produced is
It is 1.6%. The countercurrent cleaning tower used here had a tower diameter of 600 mmφ.
It has a tower height of 8200 mm and a 10-stage conical rotating plate. The total ash content in the powder copolymer recovered in the flash tank after the washing process was 50 ppm.
TiO ₂ was very small at 34 ppm, Al ₂ O ₃ was very small at 10 ppm, and the amount of volatile components was also very small at 20 ppm. The obtained powder copolymer was a clean white powder that did not cause problems such as foaming and corrosion during granulation and film formation. The composition and properties of this copolymer are shown in Table 1. Example 2 and Comparative Example 1 The same procedure as Example 1 was carried out except that the amount of DEAC supplied was changed. The results are shown in Table 1. DEAC／
It can be seen that when the TiCl ₃ (molar ratio) is less than 20, the recovered AP ratio increases and the properties of the copolymer, particularly the blocking properties, are significantly deteriorated. Comparative Examples 2 and 3 In place of the solid catalyst (B) prepared in (1) of Example 1, 160 g of titanium trichloride AA manufactured by Toho Titanium Co., Ltd.
Example 1 was carried out in the same manner as in Example 1, except that hr was supplied and the amount of DEAC supplied was changed. The AP recovery rate increased significantly, and the loss of fine solid copolymer contained therein also increased to 3-4%. The ash content in the obtained powder copolymer is

[Table] It was a yellow colored powder. The composition and properties of the obtained copolymer are shown in Table 1, and the transparency, rigidity, heat sealability, and blocking properties were deteriorated, and the blocking property was particularly poor, and the product was poor in commercial value. Also the first
From the table, this catalyst has a DEAC/TiCl ₃ (molar ratio) of 20
It can be seen that even if the value is set to 100, the effect of the present invention is not observed, but rather becomes worse. Examples 3 and 4 and Comparative Examples 4 and 5 (1) Preparation of catalyst 1 Preparation method (preparation of β-type titanium trichloride) After replacing the reactor with argon, 40% of dry hexane and 10% of titanium tetrachloride were charged. The solution was kept at -5°C. Then, a solution consisting of 30% of dry hexane and 11.6% of diethylaluminum chloride was added dropwise under such conditions that the temperature of the reaction system was maintained at -3°C or lower. After the dropwise addition was completed, stirring was continued for another 30 minutes, then the temperature was raised to 70°C, and stirring was continued for an additional hour. The mixture was then allowed to stand to separate the β-type titanium trichloride into solid and liquid, and was further washed three times with 40 kg of hexane to obtain 15 kg of a reduced product. The titanium trichloride contains 4.60% by weight Al. 2 Preparation method (Preparation of Lewis base treated solid) β-type titanium trichloride obtained by the above preparation method was
The mixture was suspended in dry hexane, then diisoamyl ether was added in a molar ratio of 1.2 to β-type titanium trichloride, and the mixture was stirred at 40°C for 1 hour. After the reaction was completed, the supernatant was taken out, washed three times with 40 g of hexane, and dried. 3 Preparation method 10 kg of the Lewis base treated solid prepared according to the above preparation method was mixed with 30 kg of dry heptane and titanium tetrachloride.
20 and treated at 70°C for 2 hours. After the reaction, the supernatant liquid was extracted, washed three times with 30% hexane, and dried to obtain a titanium trichloride solid catalyst (C). (2) Production of ethylene, propylene, butene-1 copolymer Proceed as in Example 1 except that solid catalyst (C) was used instead of solid catalyst (B) and the target copolymer composition was changed. Ta. The results are shown in Table 1. Propylene/ethylene copolymers have low rigidity and poor blocking properties. On the other hand, propylene-butene-1 copolymer has extremely poor cold resistance. Compared to these copolymers, the copolymer prepared by the method of the present invention satisfies the required physical properties to a high degree.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a simple process diagram showing an embodiment of the method of the present invention. . . . Polymerization tank, . . . Countercurrent washing tower. FIG. 2 is a flowchart to help understand the present invention.

Claims (1)

[Scope of Claims] 1 (a) titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound and further activating it; and (b) an organoaluminum compound, the molar ratio of (a) and (b) being ( Using a catalyst system with b)/(a) between 20 and 100 and a solubility parameter of 7.0
(cal/cc) In a liquid phase medium of ^1/2 or less, propylene,
Copolymerizing ethylene and butene-1,
The extracted polymerization slurry is introduced into the upper part of the countercurrent washing tower, and the solubility parameter supplied from the lower part is
7.0 (cal/cc) ^1/2 or less of the ethylene content, which is characterized by being washed by contacting with a liquid phase medium in countercurrent.
A method for producing an ethylene-propylene-butene-1 copolymer having a propylene content of 80-99 weight% and a butene-1 content of 0.5 to 15 weight%. 2. The method according to claim 1, wherein the catalyst component (b) is an alkyl aluminum halide. 3. The method according to claim 1, wherein the molar ratio (b)/(a) of catalyst components (a) and (b) is from 30 to 70. 4. A patent claim in which the ethylene content of the ethylene-propylene-butene-1 copolymer is 1 to 4% by weight, the propylene content is 86 to 98% by weight, and the butene-1 content is 1 to 10% by weight. The method described in item 1. 5. The method of claim 1, wherein the liquid phase medium is a liquid phase monomer substantially free of inert solvents. 6. The method according to claim 1, wherein 8000 parts by weight or more of the copolymer is produced per 1 part by weight of the catalyst component (a).