JPS63225613A - Manufacture of propylene block copolymer - Google Patents

Abstract

PURPOSE:To produce the title copolymer with high reactor efficiency, by supplying a specific compound into a vapor phase polymerization reaction system of the latter step to effect the polymerization reaction thereby inhibiting production of low molecular weight polymers and not allowing them to adhere on the inner wall of a reactor or to agglomerate. CONSTITUTION:In the process of effecting polymerization of propyrene in the presence of a catalyst (e.g., one comprising TiCl3 and a dialkylaluminum chloride, etc.), and then effecting (co)polymerization of an alpha-olefin (e.g., ethylene, etc.) except propylene or propylene and other alpha-olefin under a vapor phase without deactivation of the catalyst, an alcohol (e.g., n-octanol, etc.) of the formula: ROH (wherein R is a 5-20C hydrocarbon group) is applied into a vapor phase polymerization system of the latter step. Thereby, without lowering the polymerization activity, production of low molecular weight polymers is inhibited and adhesion of them on the inner wall of reactor and agglomeration of them do not occur, and a good flow condition is attained, so that long-term operation which is stable in view of the process and the quality can be done, thereby the title copolymer is produced with high reactor efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a propylene-α-olefin block copolymer. More specifically, the propylene polymer obtained without deactivating the catalyst may adhere between polymer particles or on the inner wall of the reactor, or may clog pipes or solidify in silos or hoppers in later steps. Polymerize other α-olefins or polymerize propylene and other α-olefins in the gas phase without
- It relates to a method for copolymerizing α-olefin block copolymers with olefins and producing α-olefin block copolymers with high reactor volumetric efficiency.

[Conventional technology]

Regarding the polymerization of α-olefins such as ethylene and propylene, the performance of polymerization catalysts has improved significantly in recent years, and the yield of polymer per catalyst component has dramatically increased. was sufficiently small that the catalyst removal step could be omitted.

On the other hand, methods for polymerizing these α-olefins include a slurry polymerization method carried out in an inert hydrocarbon solvent, a bulk polymerization method carried out in a liquefied monomer such as liquefied propylene,
There is a gas phase polymerization method that is carried out in the gas phase, but since the gas phase polymerization method does not use a solvent, there is no need for solvent recovery or purification steps, monomer recovery, and drying of the polymer product. It has been attracting attention in recent years because of its ease of use.

In the field of propylene and other α-olefin block copolymers, propylene polymer is produced in the first stage, and in the second stage, other α-olefins are polymerized in the gas phase, or propylene and other α-olefins are copolymerized in the gas phase. A block copolymerization method is known. Compared to methods in which the subsequent polymerization is carried out in an inert hydrocarbon solvent or in liquid propylene, the gas phase block copolymerization method has economical reasons as mentioned above, as well as the possibility of product diversification. There are also some advantages.

However, in gas phase polymerization, the reaction rate is slow because the monomer concentration is relatively low, and catalysts with good particle properties are required to form a good fluidized bed. It has been pointed out that a catalyst with excellent properties is essential, and that it is accompanied by numerous difficulties such as problems in equipment for good flow and mixing, heat removal problems, and adhesion problems. In particular, adhesion inside the reactor is not only a major hindrance to long-term stable operation, but also a deterioration in quality.

[Problem that the invention seeks to solve]

The present inventors mainly conducted intensive studies on the causes and countermeasures for the phenomenon of adhesion and deterioration of powder properties within the propylene-α-olefin gas phase copolymerization reactor in the latter stage. As a result, in the gas phase polymerization reactor and its gas circulation system, low molecular weight polymers of ethylene and propylene are likely to be produced due to the action of the organoaluminum component used as a cocatalyst, and in some cases, oily substances may be formed. It has been found that these low molecular weight polymers are the cause of adhesion and agglomeration inside the reactor, deterioration of powder properties, etc.

[Means for solving problems]

Therefore, the present inventors investigated various methods for suppressing the formation of these low molecular weight polymers, and found that supplying a specific compound into the subsequent gas phase polymerization reaction system has no effect on the polymerization reaction. It has been discovered that the production of low molecular weight polymers can be suppressed, and deterioration of powder properties, adhesion inside the reactor, and agglomeration can be prevented without causing any problems, leading to the present invention.

The gist of the present invention is to polymerize propylene or propylene and a small amount of other α-olefins in the presence of a catalyst to obtain a propylene polymer, and then to polymerize propylene and other α-olefins or other α-olefins in the gas phase. In the method for producing a propylene block copolymer copolymerized or polymerized with,
Production of a propylene block copolymer characterized by supplying an alcohol represented by the general formula Roll (in the formula, R represents a hydrocarbon group having from j to -0 carbon atoms) to the gas phase polymerization system in the subsequent stage. It's a method.

The present invention will be sequentially explained below.

In the present invention, the polymerization catalyst used includes a titanium-containing solid catalyst component and an organoaluminum compound, but is not particularly limited, and any known catalyst can be used.

As the titanium-containing solid catalyst component, known carrier-supported catalyst components containing solid magnesium compounds, titanium compound components, and nitrogen components can also be used, but preferably titanium trichloride is the main component. . As the material containing titanium trichloride as a main component, conventionally known titanium trichloride can be used. For example, titanium trichloride is activated by ball milling, titanium trichloride is extracted with a solvent, β-type titanium trichloride is treated with a complexing agent such as an ether, and further treated with titanium tetrachloride to form At Content T1
The atomic ratio to 0. /! Titanium trichloride:
In the presence of ethers, titanium tetrachloride is treated with an organoaluminum compound to form a liquid, which is further heated to form a solid with an At content of O0/! as an atomic ratio to T1. The following titanium trichloride can be mentioned.

Among these titanium trichlorides, particularly preferred is one whose aluminum content is o in the atomic ratio of aluminum to titanium.
, i z or less, preferably 0. / or less, more preferably 0.0 J or less, and contains a complexing agent. The content of the complexing agent is 0.007 in molar ratio of the complexing agent to titanium trichloride in the solid titanium trichloride-based catalyst complex.
The ratio is preferably 0.0/or more. Specifically, titanium trichloride, AtR1pX3-p (wherein R1 is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, 0 in molar ratio to aluminum halide and titanium trichloride, where p is a number of 0≦p≦2.
．． 00 complexing agent or more, such as those of the formula TiC6
3.(htRlpxs-p)a.(0)t (wherein, R
1 is a hydrocarbon group having carbon number/-20 or a halogen atom, p is a number of O≦p≦2, C is a complexing agent, a is a number of o, i z or less and t is 0.00
/ is a number greater than or equal to ).
Of course, T i Ot3 component, AIR” pX3-p
In addition to component C and complexing agent, a small amount of iodine, titanium trichloride in which part or all of the chlorine has been replaced with iodine or bromine, inorganic solids for carriers such as MgC22 and MgO, polyethylene, polypropylene, etc. It may also contain olefin polymer powder or the like. Complexing agent C
Examples include ethers, thioethers, ketones, carboxylic acid esters, amines, carboxylic acid amides, polysiloxanes, and among these, ethers and thioethers are particularly preferred. As an ether or thioether, the general formula RN 0-RNI or R"-S-R'"
' (In the formula, R" and R# represent a hydrocarbon group having a carbon number of 1 or less.) AtR" p
Examples of Xa-p include htat3, AtRIC12, and the like.

Further, it is particularly preferable that the solid titanium trichloride-based catalyst complex has an X-ray diffraction pattern having a halo of maximum intensity at a position corresponding to the strongest peak position of α-type titanium chloride (near 2θ=3220). Furthermore, it is preferable that the solid titanium trichloride-based catalyst complex is not subjected to thermal history at a temperature exceeding 130° C. during production. Furthermore, the pore radius measured using the mercury porosimeter method is 1 in 20! Cumulative pore volume between 00A and 0.02cd/f or more, especially 0, OJ ad/
t~0. / j d/ f, which is characterized by a pore volume with an extremely fine pore diameter, is particularly preferred since it is not necessary to remove non-quality polymers.

However, such a solid titanium trichloride-based catalyst complex can be produced by: (a) Precipitating titanium tetrachloride from a liquid containing liquefied titanium trichloride in the presence of an ether or thioether at a temperature of 110° C. or lower. Solid titanium trichloride obtained by reducing titanium trichloride with an organoaluminum compound or metal aluminum can be easily produced by a method such as treatment with a complexing agent and treatment with a halogen compound.

The above methods (a) and (b) have already been adopted in the
T! / issue, 75-f Hiromu! λ issue, same evening 3-2≠l issue, same day issue 11-4003, same day hiro If-10170 issue, same day KoeJit issue, JP-A-13-/1989, issue 2726, same day j
2-ta/7ri number, same j! -//1a626, same j
J-JJjt No., J-Ko uOJ'/-1 No., J-JJjt No.
3g Octopus No. 05, same J Tarlλ 05, same J Tar IJt
It is publicly known in JO issue etc. Furthermore, in addition to the methods (a) and (b), as described in Japanese Patent Publication No. 14cm27171, K, titanium tetrachloride can be reduced to solid titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound. The molar ratio is 0. ! A product prepared by adding the ether compound of -1, heating to 10-120°C, and then separating the solid may also be used.

The organoaluminum compound used as a cocatalyst for the above titanium-containing solid catalyst component has the general formula atRmxs
-m (wherein, R3 is a hydrocarbon group having carbon number/-20,
) represents 10 gen, m is 3≧m)/, represents the number of j). When the titanium-containing solid catalyst component is a carrier-supported catalyst component containing a solid magnesium compound, it is preferred to use a mixture of AtR: or AZR: and AtR:X. On the other hand, when the titanium-containing solid catalyst component is mainly composed of titanium trichloride, AtR
:X is used, but it is generally preferable to use diethylaluminum chloride, di-n-propyl aluminum chloride, diethylaluminium chloride, di-n-octyl chloride.

The titanium trichloride and organoaluminum compound shown above generally have a molar ratio of organoaluminum compound/titanium trichloride of 1 to 30. Preferably, it is used in the range from ko to is.

In the present invention, the above-mentioned catalyst may be used as it is, but it is preferable to pre-polymerize a small amount of olefin onto the catalyst made of titanium trichloride and an organoaluminum compound as a pretreatment.

In the above method, titanium trichloride and an organoaluminum compound are added to an inert solvent such as hexane, heptane, etc., and an olefin such as propylene, ethylene, butene-1, or a mixture thereof is supplied thereto for polymerization. This pretreatment is generally referred to as prepolymerization, and any known polymerization conditions may be employed.

The polymerization temperature is 30 to 70°C, and the higher the polymerization rate per unit weight of titanium trichloride, the better; however, from an equipment or economic point of view, it is less than 0. l~1oot-polymer/t-
It is generally in the range of TiO43. Furthermore, a molecular weight regulator such as hydrogen may be added during prepolymerization. Furthermore, it is preferable that the prepolymerization is carried out uniformly in a batch manner. This prepolymerization is effective in improving polymer properties such as bulk density.

An additive for improving stereoregularity may be used as a third component in the catalyst made of tita trichloride/and organoaluminum compound described above. For this purpose N, OlP
Various compounds including or 81 and hydrocarbon compounds are used.

Further, an electron donating compound may be used as the third component. Such electron-donating compounds include compounds containing one or more electron-donating atoms or groups, such as alcohols, ethers, polyethers, alkylene oxides, furans, amines, trialkylphosphines, triarylphosphines, and pyridines. , quinolines, phosphoric acid esters, phosphoric acid amides, phosphine oxides, trialkyl phosphites, triarylphosphites, ketones, carboxylic acid esters, carboxylic acid amides, and the like.

Among these, preferred are ethyl benzoate, methyl benzoate, phenyl acetate, carbonic acid esters such as methyl methacrylate, glycine esters such as dimethylchrysine ethyl ester, dimethyl glycine/phenyl ester, triphenyl phosphatate, trinonylphenyl phosphate, etc. Examples include triarylphosphites such as phite.

Furthermore, aromatic hydrocarbons such as benzene, toluene, and xylene may also be used as the third component.

The amount of the third component added is generally 0,000/-wj, preferably 0.00/-/ in molar ratio to titanium trichloride.
is within the range of

The polymerization method in the main polymerization of propylene carried out in the first stage can be carried out by known slurry polymerization, slurry polymerization in a liquefied monomer, gas phase polymerization, or the like. These polymerization methods may be either batchwise or continuous, and the reaction conditions are /-100 atm, preferably under a pressure of J--<xo atm, SO to 0°C.
, preferably in the range of 10-♂O<0>C. In slurry polymerization, inert hydrocarbon solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, etc. used in normal olefin polymerization are used as the polymerization medium. Preferably, normal hexane, normal heptane, cyclohexane, benzene, and toluene are used. Moreover, propylene itself can also be used as a medium. As a method for controlling the molecular weight of the produced polymer, a known molecular weight controlling agent such as hydrogen or diethylzinc may be appropriately added to the polymerization reaction.

Although propylene alone may be polymerized in the first stage of the present invention, propylene and a small amount of other α-olefin may be used in combination. Other α-olefins are ethylene, butene-11≠
α-olefins such as methylpentene/etc., and the amount thereof is so small that the product does not lose its properties as a propylene polymer, for example, 10% by weight or less based on propylene.

The propylene polymer obtained by the first-stage polymerization is transferred to the second-stage gas phase polymerization vessel without deactivating the catalyst contained therein, with or without removing a portion of the reaction medium.

That is, when the polymer is obtained by a solvent polymerization method, inert hydrocarbons and unreacted monomers are removed using a centrifuge, a liquid cyclone, or the like. In addition, when liquid propylene itself is used as a medium, in addition to similar known solid-liquid separation means,
It can also be directly sent to a gas phase polymerization vessel.

The most important technical feature of the present invention is that an alcohol represented by the general formula ROH (wherein R represents a hydrocarbon group having from j to 20 carbon atoms) is added to the gas phase polymerization system in the latter stage. By adding it, the formation of low molecular weight polymers of α-olefin monomers such as ethylene and propylene is suppressed, and as a result, adhesion inside the reactor, clumping phenomenon, and deterioration of powder properties are prevented, and good flow is achieved. The point is that layer formation and stable operation can be achieved.

Alcohols used in the present invention include n-pentanol, n-hexanol, n-octatool, copentanol, 3-pentanol, tert-7yl alcohol, coethylhexanol, 3-penten-/-ol. Examples include aliphatic alcohols such as cyclohexanol, alicyclic alcohols such as cyclooctatool, and aromatic alcohols such as benzyl alcohol, phenethyl alcohol, and p-methylpenzyl alcohol.

Further, although these alcohols are different from the electron-donating compounds used in the propylene polymerization in the previous step, they may be the same. That is, if it has excellent polymerization properties (polymerization activity, stereoregularity, etc.) in the propylene polymerization system in the first stage, it is added to the first stage as a third component, and also added to the second stage gas phase polymerization system. be able to.

The alcohol can be added directly to the gas phase reactor, or it can be diluted and dissolved in an inert hydrocarbon solvent or liquid propylene, or it can be added as a gas mixture with an α-olefin or propylene itself. It can also be supplied directly or after being dissolved and diluted in an inert hydrocarbon solvent such as liquid propylene.

The amount of alcohol used varies depending on the amount of organoaluminum compound present in the subsequent gas phase polymerization system, but usually the organoaluminum compound is added to the amount of organoaluminum compound supplied in the first step or to the subsequent gas phase polymerization system. Cases (for example, Tokuko Sho!!-7≠6≠ issue, Tokuko Sho 13-30
No. 424, J4-11/7/J, etc.) has an alcohol/organoaluminum molar ratio of 0.
000 /~/, preferably 0.00 /~Q,! It is. If the amount added is too large, the polymerization activity in gas phase polymerization will decrease, which is not preferable. On the other hand, if it is too small, the effect of suppressing the formation of low molecular weight polymers will not be sufficiently exhibited.

In addition, there is also a method of newly adding an inert hydrocarbon to the gas phase polymerization system in the latter stage (for example, Japanese Patent Application Laid-Open No. 17-31-05), and a method of adding a silicone compound (for example, Japanese Patent Application No. 1983-1983).
7J@? In No. 4), the method of the present invention can be used in combination and is effective, so it can be applied.

In the present invention, the α-olefin to be polymerized or copolymerized in the gas phase is an α-olefin having 2 to 1 carbon atoms, preferably ethylene or a mixture of ethylene-propylene.

The conditions for gas phase polymerization are usually JO-100°C, l~! Cape 0/
aA, the polymerization ratio of the subsequent α-olefin block copolymerization portion to the total polymer is 3~! Polymerization or copolymerization is carried out so that the amount is 0% by weight, preferably 10 to 30% by weight. When using an ethylene-propylene mixed gas, which is a more preferred embodiment, the composition of the gas is such that propylene is 10 to 10 molar, preferably 20 to 10 molar, based on the sum of ethylene and propylene.

The production method of the present invention basically consists of a first step of polymerizing propylene or propylene and a small amount of other α-olefin to obtain a propylene polymer, and a gas phase of other α-olefin or propylene and other α-olefin. and a second stage for polymerization.

However, in the present invention, the subsequent gas phase polymerization of α-olefin can be carried out in multiple stages, and the polymerization temperature, hydrogen concentration, monomer composition, and reaction amount ratio can also be changed in each reactor.

In the present invention, the equipment used for the subsequent gas phase polymerization is not particularly limited, and known equipment such as a fluidized bed, a stirred tank, a fluidized bed with a stirring device, a moving bed, etc. is preferably used, and the polymerization is carried out continuously or batchwise. .

After the completion of gas phase polymerization, the polymer taken out continuously or batchwise is subjected to inactivation treatment or deashing treatment with alkylene/oxide, alcohol, water, etc., and removal of amorphous polymer with a solvent, as necessary. You may also do the following.

The method of the present invention is characterized by the addition of an alcohol represented by the general formula ROH (in the formula, R represents a hydrocarbon group with a carbon number from ! to λO) to the gas phase polymerization system in the latter stage, resulting in adhesion,
The production of low molecular weight α-olefin polymers that cause sticking is suppressed, good powder properties are obtained, adhesion to vessel walls and clumping phenomena are eliminated, and good fluidity is achieved.
This method enables long-term stable operation in terms of process and quality, and has almost no effect on polymerization behavior such as the activity of gas phase polymerization.

〔Example〕

The present invention will be described below with reference to Examples, but the present invention is not limited thereto unless it exceeds the gist thereof.

In the following Examples and Comparative Examples, bulk density and n-hexane extraction residue were measured by the following methods.

(1) Bulk density J-Tech 13-672/(2) n-hexane extraction residue Amount remaining after extraction with boiling n-hexane for 3 hours using an improved Soxhlet extractor ('weight S>).

Example 1 (A) In a solid titanium trichloride preparation chamber 11, purified toluene j,/jt was placed in a 10 t autoclave which was sufficiently purged with nitrogen, and while stirring, n-butyl ether 41/l (5 mol), 2 μl of titanium chloride (1 mol) and diethylaluminum chloride J I 6 t (J, 4° C. mol) were added to obtain a brown homogeneous solution.

Next, the temperature was raised to 0°C, and after 30 minutes, precipitation of purple fine granular solids was observed, but the temperature remained unchanged for 2 hours≠O
Hold ℃.

Next, 5 ozt of titanium tetrachloride was added, and the temperature was raised to 2°C. After being maintained at t° C. for about 1 hour, the granular purple solid was separated and washed with n-hexane to obtain about 100 ml of solid titanium trichloride.

(B) Production of titanium trichloride containing propylene polymer (
Pretreatment) Place the gn-
Hexane! Add L and diethyl aluminum chloride 19? And the solid titanium trichloride obtained in (A) above is
Cj! After charging 2jO2 in Step 3, the temperature was maintained at 4!0°C, and a contact treatment was carried out by blowing propylene gas 2609 into the gas phase for about 60 minutes while stirring.

The solid components were then allowed to settle, and the supernatant liquid was removed by decantation and washed several times with n-hexane to obtain solid titanium trichloride containing a propylene polymer.

(C) Production of propylene-ethylene block copolymer Two reaction tanks with a stirrer with a capacity of 10001%≠001 are connected in series, and one stirred fluidized tank type gas phase polymerization tank with a capacity of 1 soot is connected in series. connected in series, the first and second
In the second reaction tank, homopolymerization of propylene was carried out in liquefied propylene, and in the third reaction tank, copolymerization of propylene and ethylene was carried out by gas phase polymerization.

The first reaction tank contains liquefied propylene, the psychocatalyst component μ obtained in (B) above, Ot/hr, cocatalyst diethylaluminum chloride/o r/hr, and methyl methacrylate 0. j29/hr and hydrogen 0.0 as a molecular weight regulator. /! kg/hr was continuously supplied. The polymerization temperature was 70°C in the first tank and 47°C in the second tank, and the slurry was continuously extracted from the first tank and supplied to the second tank. The average residence time was 11.0 hours in total for the first tank and the first type.

The polymer slurry from the first type was continuously supplied to the third tank, and gas phase polymerization was carried out while maintaining the temperature at 60° C. and the pressure at / j KG. The composition of ethylene and propylene in the gas phase is propylene/(propylene in ethylene) = 4jmolti,
H2/(propylene in ethylene) =/j Moltiny adjusted. In addition, 0.1% of n-octatool was added to the circulating gas of this gas phase polymerization system. It was supplied at r f/hr. The average residence time in this gas phase reactor is 2 to 3 hours, and the polymerized powder continuously extracted from the third tank is separated from unreacted gas and then treated with propylene oxide vapor to form a powdered polymer. Good at combining at a rate of ≠j kf/hr.

This operation was continued for 30 days, and the entire system was able to operate stably, and when the reactor was opened after the operation, no deposits or lumps were observed inside the reactor, and there was no oily residue like that observed in the comparative example. No product formation was observed.

The average weight ratio of homopolymerization and copolymerization of the polymers obtained during this period was 11//! Met. Also, the bulk density of the powder is O
0≠! ? The residual amount of / after n-hexane extraction was 27.6%.

Comparative Example 1 Continuous operation for one day was carried out in the same manner as in Example 1, except that n-octatool was not supplied to the gas phase polymerization system.

During this period, the formation of oily substances was observed at the bottom of the gas-phase reactor distribution plate, and the pressure loss of the distribution plate tended to increase over time. In addition, the bulk density of the obtained polymer powder was also
J I -0,170t/CX,.

The residual amount of n-hexane extracted was 6%, which was low.

Furthermore, when the reactor was opened after the operation was completed, sticky substances and sensitive particles were found to be attached to the upper part of the reactor free board, and formation of lumps was observed around the shaft of the stirring blade and part of the stator. Ta. Furthermore, deposits were also formed on the dispersion plate.

〔Effect of the invention〕

According to the present invention, the production of low molecular weight polymers is suppressed without reducing polymerization activity, and adhesion to the inner wall of the reactor and clumping phenomena are eliminated to achieve a good fluidity state, which improves quality from a process perspective. It also enables long-term stable operation.

Applicant Mitsubishi Chemical Industries, Ltd. Agent Patent Attorney Hase - (and 7 others) Procedural amendment (spontaneous) October 7, 1988, Day 2 Name of the invention Process for producing propylene block copolymer 3 Amendment Applicant (196) Mitsubishi Chemical Industries, Ltd. 4 Agents〒1
00 115-2 Marunouchi 2-chome, Chiyoda-ku, Tokyo 5 Subject of amendment
Contents of the amendment in Column 6 of the “Detailed Description of the Invention” of the specification (Re) “Dinormaoctyl chloride” in the second line of page 12 of the specification is corrected to “dinormaoctylaluminum chloride” .

(21, page 13, line I - page 1, hiro page, line 2: “...
Various compounds including 81 etc. and hydrocarbon compounds are used. Further, an electron donating compound may be used as the third component. "Like this..."
Various electron-donating compounds and hydrocarbon compounds including 81 and the like are used. Like this...correct it as J.

(3) On page 1 μ, line 10-//, the phrase “...carboxylic acid ester, carboxylic acid amide...” was replaced with “
...Carboxylic acid ester, carboxylic acid amide..."
I am corrected.

(4) In the same page 1ψ, line 16, [...triphenylphosphato,] is replaced with "triphenylphosphite."
I am corrected.

(5) On page 26, line 7 of the same, “...adhesive substances and powder particles”
The statement has been corrected to read "...sticky substances and fine particles."

that's all

Claims (6)

[Claims] (1) A method in which propylene is polymerized in the presence of a catalyst, and then an α-olefin other than propylene, or propylene and another α-olefin are polymerized or copolymerized in a gas phase without deactivating the catalyst, A method for producing a propylene block copolymer, which comprises supplying an alcohol represented by the general formula ROH (in the formula, R represents a hydrocarbon group having 5 to 20 carbon atoms) to the subsequent gas phase polymerization system. . (2) The method according to claim 1, wherein the polymerization catalyst comprises titanium trichloride and dialkyl aluminum chloride. (3) The polymerization catalyst is characterized in that the aluminum content is 0.15 or less in terms of the atomic ratio of aluminum to titanium, and is composed of a solid titanium trichloride-based catalyst complex containing a complexing agent and an organoaluminum compound. A method according to claim 1. (4) The polymerization catalyst is a solid titanium trichloride-based catalyst complex, and the pore radius measured by the mercury porosimeter method is 20 Å to 50 Å.
The method for producing a block copolymer according to claim 1, which uses a block copolymer having a cumulative pore volume of 0.02 cm^3/g or more between 0 Å. (5) Claims in which the polymerization catalyst is a solid titanium trichloride-based catalyst complex, which is precipitated at a temperature of 150°C or less from a liquid containing titanium trichloride liquefied in the presence of an ether or thioether. A method for producing a block copolymer according to item 1. (6) The polymerization catalyst is a solid titanium trichloride-based catalyst complex, and the solid titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound or metal aluminum is treated with a complexing agent and a halogen compound. 1. A method for producing a block copolymer according to claim 1.