Method for Propylene Block Copolymer Production

Abstract

Propylene-based block copolymers are produced in a multi-stage continuous polymerization method while reducing gel formation without excessively increasing the number of reactors, and with high catalytic efficiency. [Solution] A method for producing a propylene-based block copolymer by performing multi-stage continuous polymerization including a first step and a second step in the presence of an olefin polymerization catalyst using a gas-phase fluidized bed polymerization reactor, wherein an insert nozzle 114 having one or more discharge ports is connected to the straight body of the gas-phase fluidized bed polymerization reactor in at least one of the first and second steps, the distance from the discharge port located at the tip of the nozzle to the inner wall of the cross-section A of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is within the range of 12% to 88% of the inner diameter of the cross-section for any distance from the discharge port to the inner wall at any position on the inner circumference of the cross-section, and a specific gel formation inhibitor is supplied from the insert nozzle into the retained powder inside the reactor.

Description

Technical Field

[0001] The present invention relates to a method for producing a propylene-based block copolymer.

Background Art

[0002] Crystalline polypropylene obtained by polymerizing propylene under a stereoregular catalyst is widely and commonly used because it is lightweight, has excellent rigidity and heat resistance among thermoplastic resins, and is also easy to recycle. On the other hand, in order to improve the impact resistance, which is a drawback of crystalline polypropylene, crystalline polypropylene is produced in the first-stage polymerization, and then in the subsequent second-stage polymerization, copolymerization of propylene and another α-olefin such as ethylene is carried out to produce an amorphous propylene·α-olefin copolymer, thereby obtaining a propylene-based block copolymer. This method is widely known. For the production of such propylene-based block copolymers, a multi-stage continuous polymerization method is most commonly adopted from the perspective of economy. However, in the multi-stage continuous polymerization method, since the residence time distribution of the catalyst occurs in each polymerization tank of each stage, a distribution occurs in the polymerization amount per catalyst particle, and this non-uniformity causes a problem of generating an appearance defect called gel in the product. In addition, as a characteristic of the propylene-based block copolymer, the intrinsic viscosity η of the propylene·α-olefin copolymer may be increased to improve melt tension, improve flow marks, and reduce surface gloss (matting). However, it is known that the problem of this gel particularly easily occurs in such polymers. As one of the countermeasures, a method of narrowing the residence time distribution by increasing the number of reactors for crystalline propylene polymerization, which is the first step, is known (for example, Patent Document 1).

[0003] Patent Document 2 describes a prediction that in a multi-stage continuous polymerization method of propylene-based block copolymers, small particles such as catalyst particles that pass through the first step with a short residence time, or catalyst particles that contain only a small amount of the first step product, undergo polymerization in the second step, resulting in the generation of particles containing a higher-than-average amount of the propylene-ethylene copolymer, which is difficult to disperse, and thus the main cause of gel formation. Furthermore, Patent Document 2 proposes a method for continuously producing a propylene-based block copolymer containing a propylene-α-olefin copolymer by gas-phase polymerization, in which a mixed reaction inhibitor containing a specific polyoxyalkylene compound and a specific alcohol compound in specific proportions is supplied to the reactor for the second step, propylene-ethylene copolymerization, as a mixed flow with liquefied propylene.According to this method, polymerization can be suppressed throughout the entire particle for small particles and only on the surface portion for large particles, and the catalytic activity of the large particles, which account for the majority of the catalytic activity, remains, thereby suppressing a decrease in catalytic activity while exhibiting an excellent gel formation suppression effect. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 62-149711 [Patent Document 2] Japanese Patent Publication No. 2022-014443 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] As mentioned above, propylene-based block copolymers containing propylene-α-olefin copolymers with high intrinsic viscosity have excellent properties and are used in industrial sheets and automotive components, but there have been concerns about product appearance defects due to gel formation. The method disclosed in Patent Document 1, which involves increasing the number of reactors in the first step, crystalline propylene polymerization, leads to increased plant construction costs and operational complexity due to an increase in plant operation management items, thus requiring further technological improvements. The manufacturing method disclosed in Patent Document 2, which involves supplying a mixed reaction inhibitor containing a specific polyoxyalkylene compound and a specific alcohol compound in specific proportions to the reactor of the second step, propylene-ethylene copolymerization, as a mixed stream with liquefied propylene, is not applicable to operations that do not use liquefied propylene due to reactor temperature control and other factors. Therefore, the development of a different method for supplying the reaction inhibitor has been desired.

[0006] In view of the problems of the prior art described above, the object of the present invention is to provide a method for producing a propylene-based block copolymer in a multi-stage continuous polymerization method while reducing the amount of gel without excessively increasing the number of reactors, and with high catalytic efficiency. [Means for solving the problem]

[0007] The inventors predicted that the main cause of gel formation is the copolymerization of α-olefins by small particles, such as catalyst particles that pass through the first step with a short residence time and catalyst particles containing a small amount of the first step product, with α-olefins in the second step, resulting in the generation of particles containing a higher-than-average amount of the propylene-α-olefin copolymer, which is difficult to disperse. Based on this prediction, the inventors diligently investigated the idea that gel formation in the intermediate product can be suppressed by selectively deactivating the catalytic activity of the catalyst particles present in the small particles by using a gel formation inhibitor that is concentrated at relatively shallow depths of the particles. As a result, in a method for continuously producing propylene-based block copolymers containing propylene-α-olefin copolymers, it was found that by supplying a specific gel formation inhibitor into the retained powder inside the reactor in a specific manner, the dispersibility of the gel formation inhibitor is improved, the gel formation inhibitor is uniformly dispersed in the retained powder without dripping onto the inner surface of the reactor, and exhibits an excellent gel formation suppression effect while suppressing a decrease in catalytic activity. Based on these findings, the inventors have completed the present invention.

[0008] In other words, the present invention provides a method for producing propylene-based block copolymers as described in [1] to [6] below. [1] A method for producing a propylene-based block copolymer by performing multi-step continuous polymerization including a first step and a second step in the presence of an olefin polymerization catalyst using a gas-phase fluidized bed polymerization reactor, In at least one of the first and second steps, an insert nozzle having at least one discharge port is connected to the straight body of the gas-phase fluidized bed polymerization reactor, and the distance from the discharge port located at the furthest tip of the insert nozzle to the inner wall of the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is within the range of 12% to 88% of the inner diameter of the cross-section, for any distance from the discharge port to the inner wall at any position on the inner circumference of the cross-section. A method for producing a propylene-based block copolymer, comprising supplying a gel formation inhibitor, which is a compound represented by the following general formula (1), from an insert nozzle into the retained powder inside the reactor. [General formula (1)] HO-[CH2-CH(CH3)-O] p -[CH2-CH2-O] q -[CH2-CH(CH3)-O] r -R 1 (In general formula (1), p, q, and r are each independent integers from 1 to 60, and R 1 (This represents a hydrogen atom or a hydrocarbon group with 1 to 25 carbon atoms.)

[0009] [2] The method for producing a propylene-based block copolymer according to [1], wherein the gel-forming inhibitor is supplied in a ratio of 0.001% to 0.1% by mass relative to the amount of propylene-based block copolymer produced. It is preferable. [3] A method for producing a propylene-based block copolymer according to [1] or [2], further comprising supplying a reaction inhibitor represented by the following general formula (2) into the retained powder inside the reactor. [General formula (2)] HO-R 2 (In general formula (2), R 2 (This represents a saturated hydrocarbon group with 1 to 10 carbon atoms.) [4] A method for producing a propylene-based block copolymer according to [3], wherein the amount of gel formation inhibitor supplied is 10 to 150 parts by mass per 100 parts by mass of reaction inhibitor. [5] A method for producing a propylene-based block copolymer according to any one of [1] to [4], wherein polymerization is carried out in the presence of a solid catalyst component containing magnesium, titanium, halogen and an electron-donating compound as an internal donor, and an olefin polymerization catalyst containing an organoaluminum compound. [6] A method for producing a propylene block copolymer according to any one of [1] to [5], comprising: producing a crystalline propylene polymer in a first step using one or more gas-phase fluidized bed polymerization reactors; and subsequently producing an amorphous propylene-α-olefin copolymer in the presence of the crystalline propylene polymer in a second step using one or more gas-phase polymerization reactors. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for producing propylene-based block copolymers in a multi-stage continuous gas-phase fluidized bed polymerization method while reducing gel formation without excessively increasing the number of reactors, and with high catalytic efficiency. [Brief explanation of the drawing]

[0011] [Figure 1]Figure 1 is a schematic diagram illustrating an example of the layout of a continuous vertical gas-phase fluidized bed polymerization reactor. [Figure 2] Figure 2 is a vertical cross-sectional view showing the insert nozzle 114 connected to the straight section of the first reactor 100 of the continuous vertical gas-phase fluidized bed polymerization reactor shown in Figure 1. [Figure 3] Figure 3 is a perspective view showing the insert nozzle 114 connected to the straight section of the first reactor 100 of the continuous vertical gas-phase fluidized bed polymerization reactor shown in Figure 1. [Figure 4] Figure 4 is a plan view of the cross-section A shown in Figures 2 and 3, viewed from directly above, illustrating an example of adjusting the position of the discharge port of the insert nozzle. [Figure 5] Figure 5 is a plan view of cross-section A seen from directly above, but it is a diagram used to explain from a different perspective than Figure 4, and it illustrates an example of adjusting the position of the discharge port of the insert nozzle. [Figure 6] Figure 6 is a plan view illustrating an example of adjusting the position of the insert nozzle's discharge port by considering the shortest diameter of the cross-sectional shape as the inner diameter, since the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is not perfectly circular. [Modes for carrying out the invention]

[0012] The present invention provides a method for producing a propylene-based block copolymer by performing multi-step continuous polymerization including a first step and a second step in the presence of an olefin polymerization catalyst using a gas-phase fluidized bed polymerization reactor, In at least one of the first and second steps, an insert nozzle having at least one discharge port is connected to the straight body of the gas-phase fluidized bed polymerization reactor, and the distance from the discharge port located at the furthest tip of the insert nozzle to the inner wall of the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is within the range of 12% to 88% of the inner diameter of the cross-section, for any distance from the discharge port to the inner wall at any position on the inner circumference of the cross-section. A gel formation inhibitor, which is a compound represented by the following general formula (1), is supplied from the insert nozzle into the retained powder inside the reactor. [General formula (1)] HO-[CH2-CH(CH3)-O] p -[CH2-CH2-O] q -[CH2-CH(CH3)-O] r -R 1 (In general formula (1), p, q, and r are each independently an integer of 1 to 60, and R 1 represents a hydrogen atom or a hydrocarbon group having 1 to 25 carbon atoms.)

[0013] The production method of the present invention can be carried out, for example, using the continuous vertical gas-phase fluidized bed polymerization reactor shown in FIG. 1. The continuous vertical gas-phase fluidized bed polymerization reactor shown in FIG. 1 includes a gas-phase fluidized bed polymerization reactor (first reactor 100) for carrying out the first step and a gas-phase fluidized bed polymerization reactor (second reactor 200) for carrying out the second step. An insert nozzle 114 is connected to the straight body part of the first reactor 100, and an insert nozzle 213 is connected to the straight body part of the second reactor 200. Details of the distance between the discharge port of the insert nozzle and the inner wall of the gas-phase fluidized bed polymerization reactor will be described later.

[0014] The production method of the propylene-based block copolymer of the present invention includes a first step and a second step as basic steps. In the first step, homopolymerization of propylene or copolymerization of propylene with at least one comonomer selected from the group consisting of ethylene and α-olefins having 4 to 8 carbon atoms is carried out using at least one gas-phase fluidized bed polymerization reactor to produce a crystalline propylene-based resin. Subsequently, in the second step, copolymerization of propylene with at least one comonomer selected from the group consisting of ethylene and α-olefins having 4 to 8 carbon atoms is carried out using at least one gas-phase polymerization reactor to continuously produce an amorphous propylene-α-olefin copolymer.

[0015] In the present invention, an insert nozzle having at least one discharge port is connected to the straight body of a gas-phase fluidized bed polymerization reactor in at least one of the first and second steps, and the discharge port located at the very tip of the insert nozzle is positioned such that the distance from the discharge port to the inner wall of the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is within the range of 12% to 88% of the inner diameter of the cross-section, regardless of the distance from the discharge port to the inner wall at any position on the inner circumference of the cross-section. When the gel formation inhibitor is supplied into the retained powder inside the reactor through the insert nozzle described above, adhesion of the gel formation inhibitor to the wall surface is reduced, and the gel formation inhibitor is uniformly dispersed in the retained powder, thereby suppressing a decrease in catalytic activity while exhibiting an excellent gel formation suppression effect. Therefore, the method for producing propylene-based block copolymers of the present invention allows for the production of propylene-based block copolymers containing propylene-α-olefin copolymers in a multi-stage continuous polymerization method without excessively increasing the number of reactors in the first step, while reducing gel formation, and with high catalytic efficiency even without supplying the gel formation inhibitor as a mixed flow with liquefied propylene.

[0016] Furthermore, in the present invention, a compound represented by the specific formula (1) in the order of (poly)oxypropylene-(poly)oxyethylene-(poly)oxypropylene is used as a gel formation inhibitor. Because the compound in the order of (poly)oxypropylene-(poly)oxyethylene-(poly)oxypropylene has (poly)oxypropylene at both ends, it has high solubility in organic solvents and is easy to supply when used in a diluted state with an organic solvent. In addition, the compound in the order of (poly)oxypropylene-(poly)oxyethylene-(poly)oxypropylene is more soluble in hydrophobic hydrocarbon solvents compared to the compound in the order of (poly)oxyethylene-(poly)oxypropylene-(poly)oxyethylene. Therefore, by diluting the compound represented by formula (1) in a hydrocarbon solvent according to the gel formation inhibitory effect, the amount of gel formation inhibitor used can be reduced, and manufacturing costs can be suppressed.

[0017] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is just one example of an embodiment of the present invention, and the present invention is not limited to the following description unless it exceeds the gist of the invention. In this specification, the "~" symbol indicating a numerical range is used to mean that the numbers before and after it are included as the lower and upper limits, respectively.

[0018] I. Catalysts for Olefin Polymerization The catalyst for olefin polymerization used in the present invention is not particularly limited. For example, any catalyst capable of producing polypropylene polymers with excellent stereoregularity can be appropriately selected from among Ziegler catalysts and metallocene catalysts. Preferably, a so-called Ziegler catalyst is used, comprising component (A): a solid catalyst component containing magnesium, titanium, and halogen, and component (B): an organoaluminum compound.

[0019] 1. Component (A): Solid catalyst component The solid catalyst component used in the production of the polypropylene-based block copolymer of the present invention is not particularly limited in type, as long as it contains magnesium, titanium, and halogen; known catalysts can be used. Examples of solid catalyst components include magnesium chloride-supported Ziegler-Natta catalysts, which are formed by supporting titanium tetrachloride on a carrier such as magnesium chloride and reacting it with electron donors such as ethers or esters as internal donors (see, for example, Japanese Patent Publication Nos. 58-157808, 58-83006, 58-5310, and 61-218606). Examples of commercially available catalysts that can be used in the manufacturing method of the present invention include the THC catalyst JC type manufactured by Toho Titanium Co., Ltd. (described in "Structural Control, Composite Formation, and Molding Processing Technology of Polypropylene," p. 23, Japan Technical Information Association, 2016).

[0020] The solid catalyst component preferably contains an electron donor as an internal donor. In polymerization technology using Ziegler catalysts, it is generally believed that the functions of internal and external donors are different. Internal donors are donors used simultaneously when titanium compounds are supported on magnesium compounds to form active sites. They control the coordination site of titanium atoms and alter the electronic state of the coordinating titanium atoms. On the other hand, external donors alter the properties of already existing active sites. For example, by using an external donor on a prepared solid catalyst component, it is possible to change it into a highly stereospecific active site or poison an active site that generates amorphous components, thereby making it possible to produce a propylene polymer with higher stereoregularity and fewer amorphous components.

[0021] Examples of electron-donating compounds (internal donors) include oxygen-containing electron-donating compounds such as alcohols, phenols, ketones, aldehydes, carboxylic acids, esters of organic or inorganic acids, ethers, acid amides, and acid anhydrides; nitrogen-containing electron-donating compounds such as ammonia, amines, nitriles, and isocyanates; and sulfur-containing electron-donating compounds such as sulfonic acid esters. A specific example is the compound described in paragraph 0037 of Japanese Patent Publication No. 2010-70584. These electron-donating compounds can be used individually or in combination with other compounds.

[0022] Solid catalyst components can be prepared by contacting magnesium compounds, titanium compounds, halogen compounds, and optionally electron-donating compounds as internal donors. As one means of improving stereoregularity, free titanium species present in the catalyst may be sufficiently removed. For example, as described in Japanese Patent Publication No. 2013-28705 (Example 8), Japanese Patent Publication No. 2014-37521, and Japanese Patent Publication No. 2014-162905, in the manufacturing process of a magnesium chloride-supported catalyst, free titanium species that cause low stereoregularity in polypropylene components can be removed by repeatedly washing with a solvent, thereby achieving high stereoregularity. The solid catalyst component of the present invention may be further contacted with an organoaluminum compound, an alkoxysilane compound, a vinylsilane compound, etc., after the above-described contact treatment. The organoaluminum compound used in this contact treatment may be the same as or different from the organoaluminum compound (B) described later, which is used as a co-catalyst.

[0023] It is preferable to use solid catalyst components after prepolymerization treatment. Prepolymerization treatment refers to a process in which a small amount of polymer is pre-generated on the catalyst component. The prepolymerization treatment is preferably carried out in the presence of an organoaluminum compound. As the organoaluminum compound, the same organoaluminum compound as component (B) used as a co-catalyst can be used. The organoaluminum compound may be used alone or as a mixture of two or more. The amount of organoaluminum compound used is usually in the range of 0.1 to 40 moles, preferably 0.3 to 20 moles, of the organoaluminum compound per mole of titanium atoms.

[0024] In the prepolymerization treatment, it is preferable to use organosilicon compounds. Preferred organosilicon compounds include n-propylmethyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, t-butylethyldimethoxysilane, t-butyl-n-propyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylethyldimethoxysilane, dicyclopentyldimethoxysilane, di-i-propyldimethoxysilane, di-i-butyldimethoxysilane, i-propyli-butyldimethoxysilane, t-butyltriethoxysilane, bisdiethylaminodimethoxysilane, diethylaminotriethoxysilane, and bis(perhydroisoquinolino)dimethoxysilane. These may be used individually or as a mixture of two or more. The organosilicon compound may be used in an amount ranging from 0.01 to 10 moles per mole of organoaluminum compound.

[0025] Examples of monomers used in the prepolymerization treatment include ethylene, propylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 4-methyl-1-pentene, 3-methyl-1-pentene, styrene, α-methylstyrene, allylbenzene, chlorostyrene, 1,3-butadiene, isoprene, 1,3-pentadiene, 1,5-hexadiene, 2,6-octadiene, dicyclopentadiene, 1,3-cyclohexadiene, 1,9-decadiene, and divinylbenzene. These may be used individually or as mixtures of two or more.

[0026] The conditions for the prepolymerization treatment are preferably a polymerization temperature of 0 to 80°C, a polymerization time of 10 minutes to 48 hours, and a prepolymerization amount of 0.1 to 100 g, preferably 0.5 to 50 g, per gram of solid catalyst component. The prepolymerization treatment is generally preferably carried out under stirring, and an inert solvent may be present at that time. Inert solvents that can be used in the prepolymerization treatment include hexane, heptane, octane, decane, dodecane, liquid paraffin, and silicone oil. Molecular weight adjusting agents such as hydrogen can be used to adjust the molecular weight of the polymer produced during the prepolymerization treatment.

[0027] 2. Component (B): Organoaluminum compound Organoaluminum compounds are used as co-catalysts to activate the solid catalyst component. Examples of organoaluminum compounds include trialkylaluminum such as trimethylaluminum, triethylaluminum, and triisobutylaluminum; alkylaluminum halides such as diethylaluminum chloride and diisobutylaluminum chloride; alkylaluminum hydrides such as diethylaluminum hydride; alkylaluminum alkoxides such as diethylaluminum ethoxide; aluminumoxanes such as methylaluminoxane and tetrabutylaluminoxane; and complex organoaluminum compounds such as lithium aluminum tetraethyl. It is also possible to use a mixture of two or more of these compounds.

[0028] The amount of organoaluminum compound (B) used is preferably in the range of 1 to 5,000, and particularly preferably in the range of 10 to 500, in terms of its molar ratio (moles of organoaluminum compound / moles of titanium atoms in the solid catalyst component) to the titanium component constituting the solid catalyst component (A). When using a magnesium chloride-supported Ziegler-Natta catalyst as a catalyst, it is preferable to use the organoaluminum compound in a molar ratio (moles of organoaluminum compound / moles of magnesium atoms) within the range of 1 to 200 relative to the magnesium component constituting the catalyst for polymerization.

[0029] 3. Electron-donating compounds as external donors In the present invention, the catalyst for olefin polymerization may contain an electron-donating compound as an external donor as a component. In polymerization technology using Ziegler catalysts, as mentioned above, external donors alter the properties of already formed active sites. For example, by using an external donor on a prepared solid catalyst component, it is possible to change the active sites into highly stereospecific ones or poison active sites that generate amorphous components, thereby enabling the production of propylene polymers with higher stereoregularity and fewer amorphous components.

[0030] Examples of electron-donating compounds (external donors) include organosilicon compounds such as n-propylmethyldimethoxysilane, t-butylmethyldimethoxysilane, and t-butylmethyldiethoxysilane; compounds having at least two ether bonds, such as 2,2-diisopropyl-1,3-dimethoxypropane and 2,2-diisobutyl-1,3-dimethoxypropane; compounds having a C(=O)N bond in the molecule, such as tetramethylurea, 1,3-dimethyl-2-imidazolidinone, and 1-ethyl-2-pyrrolidinone; sulfite ester compounds such as dimethyl sulfite and diethyl sulfite; esters such as ethyl acetate, butyl benzoate, p-methyl tolulate, and dibutyl phthalate; ketones such as acetone and methyl isobutyl ketone; ethers such as diethyl ether; organic acids such as benzoic acid and propionic acid; and alcohols such as ethanol and butanol. One or more electron-donating compounds can be used.

[0031] The amount of electron-donating compound (external donor) used is preferably in the range of 0.01 to 10,000, and particularly preferably in the range of 0.5 to 500, in terms of its molar ratio to the titanium constituting the solid catalyst component (moles of electron-donating compound / moles of titanium atoms in the solid catalyst component).

[0032] II. Method for Propylene Block Copolymer Production 1. Polymerization process The present invention provides a method for producing a propylene-based block copolymer by performing multi-stage continuous polymerization, including a first step and a second step, in the presence of an olefin polymerization catalyst using a gas-phase fluidized bed polymerization reactor. The present invention provides a method for producing a propylene-based block copolymer, which involves, in the first step, using one or more gas-phase fluidized bed polymerization reactors, polymerizing propylene alone or copolymerizing propylene with a relatively small amount of comonomer to produce a crystalline propylene polymer in the presence of an olefin polymerization catalyst containing a solid catalyst component (A) and an organoaluminum compound (B); and in the subsequent second step, using one or more gas-phase polymerization reactors, copolymerizing propylene with a relatively large amount of comonomer in the presence of the crystalline propylene polymer containing the olefin polymerization catalyst obtained in the first step to produce an amorphous propylene-α-olefin copolymer.

[0033] In the present invention, the crystalline propylene polymer refers to a polymer that has stereoregularity and can form lamellae, and means a propylene homopolymer or a copolymer with a relatively low comonomer content that has propylene as its basic skeleton. As the comonomer, at least one selected from the group consisting of ethylene and linear or branched α-olefins having 4 to 8 carbon atoms can be used, and generally ethylene or 1-butene is preferred, with ethylene being particularly preferred. The crystalline propylene polymer is a propylene homopolymer or propylene-α-olefin copolymer having a comonomer content of preferably 0% to 10% by mass, more preferably 0% to 3% by mass, and even more preferably 0% to 0.3% by mass.

[0034] On the other hand, in the present invention, the amorphous propylene-α-olefin polymer refers to a component that is dissolved and extracted at a temperature lower than the temperature range in which the crystalline propylene polymer dissolves, in various methods for separating olefin polymers into different temperature ranges based on the temperature dependence of their solubility in a solvent, such as CFC-IR described later. In other words, it refers to a propylene copolymer with a relatively high comonomer content, and as the comonomer, at least one selected from the group consisting of ethylene and linear or branched α-olefins having 4 to 8 carbon atoms can be used, and generally ethylene or 1-butene is selected, with ethylene being more preferred. The comonomer content of the amorphous propylene-α-olefin polymer is preferably in the range of 10% to 90% by mass, and more preferably in the range of 20% to 80% by mass.

[0035] The polymerization method of the present invention employs a fluidized bed vapor phase polymerization method that substantially avoids the use of liquid solvents and keeps each monomer in a gaseous state, so that the olefin polymerization catalyst and monomers can efficiently come into contact and the production efficiency per catalyst is good. Continuous and batch polymerization methods are applicable. The number of polymerization reactors may be one or more for both the first and second steps. The first step is carried out in one or more gas-phase fluidized bed polymerization reactors, and the second step is carried out in one or more gas-phase fluidized bed polymerization reactors. If there are multiple polymerization reactors, they may be connected in series or in parallel.

[0036] The polymerization temperature is preferably 0°C to 90°C, more preferably 30°C to 85°C, and even more preferably 45°C to 80°C. The polymerization pressure is preferably 0.1 MPaG to 5 MPaG, more preferably 0.5 MPaG to 4 MPaG. Generally, selecting higher temperatures and pressures can increase the productivity per gram of catalyst. However, this also makes it difficult to eliminate localized heat generation, leading to the generation of fine powder due to the breakdown of growing particles, and the formation of aggregates and clumps due to fusion. Therefore, the above temperature and pressure ranges are chosen to balance the productivity per gram of catalyst with the elimination of localized heat generation. The residence time can be adjusted as needed to suit the configuration of the polymerization tank, and is generally set within the range of 30 minutes to 10 hours. A preferred residence time is within 4 hours, and more preferably within 3 hours. Generally, selecting a longer residence time can increase the productivity per gram of catalyst, but if the residence time is excessive, the rate of increase in productivity per gram of catalyst with respect to the increase in residence time decreases. Therefore, the residence time should be set within the above range, taking into consideration the productivity per gram of catalyst.

[0037] In the method for producing a propylene-based block copolymer of the present invention, it is preferable from the viewpoint of productivity to produce 10,000 g or more of crystalline propylene polymer per 1 g of the olefin polymerization catalyst in the first step, and more preferable to produce 15,000 g or more of crystalline propylene polymer per 1 g of the olefin polymerization catalyst.

[0038] 2. Gel formation inhibitors The gel formation inhibitor used in the present invention is a compound represented by the following general formula (1). [General formula (1)] HO-[CH2-CH(CH3)-O] p -[CH2-CH2-O] q -[CH2-CH(CH3)-O] r -R 1 (In general formula (1), p, q, and r are each independent integers from 1 to 60, and R 1 (This represents a hydrogen atom or a hydrocarbon group with 1 to 25 carbon atoms.)

[0039] The compound represented by general formula (1) is a compound having an alcoholic hydroxyl group, and therefore has a catalyst deactivating effect and functions as a gel formation inhibitor. By adding the compound represented by general formula (1) in the first or second step of a multi-stage continuous gas-phase fluidized bed polymerization method, gel formation is prevented. The compound represented by general formula (1) may be added in both the first and second steps. Here, ambient temperature is defined as the range of 0°C to 40°C, more precisely 25°C, and ambient pressure is defined as the range of 0.09 MPa to 0.11 MPa, more precisely 0.10 MPa.

[0040] In a multi-stage continuous gas-phase fluidized bed polymerization method for propylene-based block copolymers containing propylene-α-olefin copolymers, the intermediate product of the first step contains a mixture of small particles such as catalyst particles themselves that do not contain the product of the first step, polymer particles in a primary particle state where a small amount of the product of the first step is deposited on a single catalyst particle, and small particles such as small-diameter powder particles that have not undergone secondary particle formation, as well as large particles that have grown larger due to the secondary particle formation of polymer particles. Since the gel formation inhibitor easily penetrates the entirety of small particles, it is presumed that when the gel formation inhibitor is brought into contact with small particles, the catalytic activity of all or most of the catalyst particles contained in the small particles will be deactivated, and the polymerization ability of the small particles will be almost completely lost. On the other hand, since the gel formation inhibitor is ubiquitous at relatively shallow depths in large particles, it is presumed that when the gel formation inhibitor is brought into contact with large particles, only the catalyst particles located near the surface of the large particles will be deactivated, while the deactivation of catalyst particles located in deeper parts will be avoided, and the polymerization ability of the large particles will be maintained even after contact with the gel formation inhibitor. It is hypothesized that the above-mentioned gel formation inhibitor can adjust the penetration of powder particles, which are intermediate products of the polymerization reaction, by balancing hydrophobicity and hydrophilicity, as well as by the interaction of molecular sizes. Therefore, if a gel formation inhibitor is added to the intermediate product of the polymerization reaction in the second step, either before or early after the start of production of the propylene-α-olefin copolymer, the catalytic activity of the catalyst particles present in the small particles is selectively deactivated. This reduces the generation of powder particles containing a higher-than-average amount of the difficult-to-disperse propylene-α-olefin copolymer, thereby suppressing gel formation.

[0041] Furthermore, since the proportion of small particles present in the intermediate product of the first step is smaller than the proportion of large particles coexisting therein, the amount of catalytic activity possessed by the small particles in the intermediate product is smaller than the total amount of catalytic activity possessed by the intermediate product. Although some of the catalytic activity possessed by the intermediate product is lost when the gel formation inhibitor is applied to the intermediate product, the loss of catalytic activity caused by selectively deactivating the catalytic activity of the small particles is small. Therefore, the gel formation inhibitor described above can be used in a multi-stage continuous gas-phase fluidized bed polymerization method of a propylene-based block copolymer containing a propylene-α-olefin copolymer to produce the propylene-based block copolymer with high catalytic efficiency while reducing the amount of gel.

[0042] As described above, it is presumed that the gel formation inhibitor, in the multi-stage continuous gas-phase fluidized bed polymerization method of propylene-based block copolymers, is ubiquitous in large particles at relatively shallow depths within the intermediate product of the polymerization reaction, while penetrating the entire surface of small particles and selectively deactivating the catalytic activity of catalyst particles present within the small particles, thereby suppressing gel formation in the intermediate product. However, the present invention is not limited in any way by the validity of the presumed mechanism of action described above.

[0043] The compound represented by the general formula (1) has a structure in which (poly)oxypropylene-(poly)oxyethylene-(poly)oxypropylene is arranged in that order. The (poly)oxypropylene skeleton functions as a hydrophobic group within the molecule of the compound represented by the general formula (1), influencing its permeability to polypropylene particles and its surface potential as a surfactant, and improving its solubility or compatibility with reaction inhibitors consisting of alcohol compounds, which will be described later. On the other hand, the (poly)oxyethylene skeleton functions as a hydrophilic group within the molecule of the compound represented by the general formula (1), influencing its permeability to polypropylene particles and its surface potential as a surfactant. Therefore, by appropriately changing the size of the (poly)oxypropylene skeleton and the (poly)oxyethylene skeleton contained in the molecule of the compound represented by the general formula (1), and balancing the position, occupancy rate, and hydrophobicity or hydrophilicity of the hydrophobic or hydrophilic parts within the molecule, it is possible to produce low permeability to polypropylene particles and a surface potential resistance-reducing effect as a surfactant of the compound represented by the general formula (1), and furthermore, to improve solubility or compatibility with reaction inhibitors consisting of alcohol compounds.

[0044] The number of oxypropylene units constituting the (poly)oxypropylene skeleton, i.e., the signs p and r in general formula (1), are independently integers between 1 and 60, in order to provide an appropriate balance of hydrophilicity and hydrophobicity, which results in low permeability to polypropylene particles, a reduction in surface potential resistance as a surfactant, and improved solubility and compatibility with reaction inhibitors consisting of alcohol compounds. The hydrophobic (poly)oxypropylene skeleton is thought to provide dispersibility properties in hydrocarbon solvents and olefins. While p+r is 120 or less, for ease of handling during manufacturing, such as viscosity adjustment, p+r may be 100 or less, or even 80 or less. Furthermore, while p+r is 2 or more, for hydrophobic functionality, p+r may be 10 or more, 15 or more, or even 20 or more.

[0045] The number of oxyethylene units constituting the (poly)oxyethylene skeleton, i.e., the sign q in general formula (1), is an integer between 1 and 60, in order to provide an appropriate balance of hydrophilicity and hydrophobicity in order to produce low permeability to polypropylene particles and a reduction in surface potential resistance as a surfactant. From the standpoint of hydrophilicity, q may be 40 or less, 35 or less, 30 or less, or 25 or less.

[0046] Furthermore, in order to possess properties such as low permeability to polypropylene particles and reduced surface potential resistance as a surfactant, and to avoid handling problems during manufacturing, the range of p+q+r is 3≦p+q+r, may be 10≦p+q+r, or 15≦p+q+r. On the other hand, although p+q+r≦180, if p+q+r is too large, it may cause handling problems during manufacturing, such as becoming solid at room temperature or having high viscosity. Therefore, the range of p+q+r may be p+q+r≦120, may be p+q+r≦100, or may be p+q+r≦80.

[0047] R in the general formula (1) above 1 R represents a hydrogen atom or a hydrocarbon group having 1 to 25 carbon atoms. 1 The hydrocarbon group having 1 to 25 carbon atoms in R may be a hydrocarbon group having 5 to 20 carbon atoms, a saturated hydrocarbon group having 5 to 20 carbon atoms, a hydrocarbon group having 10 to 20 carbon atoms, or a saturated hydrocarbon group having 10 to 20 carbon atoms. 1 When hydrocarbon groups in this material fall within this range, they tend to function as hydrophobic groups, resulting in properties such as low permeability to polypropylene particles and reduced surface potential resistance as a surfactant. R in the general formula (1) above 1 This could be a hydrogen atom.

[0048] The compound represented by general formula (1) used in the gel formation inhibitor of the present invention may be a single component or a mixture of multiple components. The values ​​of p, q, and r may each be average values.

[0049] The number-average molecular weight of the compound represented by the general formula (1) used in the present invention may have a lower limit of 500 or more, 700 or more, 900 or more, 1200 or more, or 1500 or more, from the viewpoint of viscosity and affinity with the solvent. On the other hand, from the viewpoint of ease of supplying the compound represented by the general formula (1), the upper limit may be 8000 or less, 6000 or less, or 5000 or less. Any combination of the upper and lower limits can be adopted.

[0050] The compound represented by the general formula (1) used in the present invention can be any commercially available product that is appropriate to the description. Examples of commercially available products include those sold under trade names such as Pluronic (BASF) and Adeka Pluronic (ADEKA), and examples of structures such as 31R1, 25R1, 10R5, 10R8, 17R2, 17R4, 25R2, and 25R4.

[0051] The gel formation inhibitor, which is a compound represented by the following general formula (1), is supplied in a ratio of typically 0.001% to 0.1% by mass (10 ppm to 1000 ppm by mass), preferably 0.0015% to 0.07% by mass, and more preferably 0.0020% to 0.05% by mass, relative to the amount of propylene-based block copolymer produced after the first and second steps. By satisfying the above ratio, gel formation can be suppressed without reducing catalytic activity.

[0052] The gel formation inhibitor is supplied in a molar ratio of preferably 0.001 to 0.3, more preferably 0.003 to 0.2, and even more preferably 0.005 to 0.1 relative to the organoaluminum compound (B) supplied in the first step. By satisfying the above ratios, there is an advantage in that gel formation can be suppressed without reducing catalytic activity.

[0053] 3. Reaction inhibitors In the present invention, in addition to the gel formation inhibitor, a reaction inhibitor represented by the following general formula (2) may also be supplied to the powder held inside the gas-phase fluidized bed polymerization reactor.

[0054] [General formula (2)] HO-R 2 (In general formula (2), R 2 (This represents a saturated hydrocarbon group with 1 to 10 carbon atoms.) In the reaction inhibitor represented by the general formula (2) above, R 2 R is a saturated hydrocarbon group having 1 to 10 carbon atoms. 2 This is more preferably a saturated hydrocarbon group having 2 to 8 carbon atoms, and even more preferably a saturated hydrocarbon group having 2 to 3 carbon atoms. R 2 If the carbon number exceeds 10, drying and removal becomes difficult, potentially causing problems such as odor in the final product. The most suitable alcohol compound is ethanol, which has two carbon atoms. Caution is necessary regarding the potential harmful effects on the human body of methanol, which has one carbon atom.

[0055] While the above-mentioned reaction inhibitor is not essential in this invention, when it is difficult to sufficiently suppress the reaction of particles in the reactor using only the gel formation inhibitor, supplying the reaction inhibitor to the reactor in combination with the gel formation inhibitor makes it possible to more strongly suppress the reaction on small particles without excessively suppressing the reaction on large particles, thereby avoiding the wasteful use of the gel formation inhibitor.

[0056] The reaction inhibitor should be used in such a way that the amount of gel formation inhibitor supplied is 10 to 150 parts by mass per 100 parts by mass of the reaction inhibitor. The amount of gel formation inhibitor supplied per 100 parts by mass of the reaction inhibitor may be 140 parts by mass or less, and even more 130 parts by mass or less. By combining the gel formation inhibitor and the reaction inhibitor in the appropriate ratio described above, the reaction inhibitor can prevent / inhibit self-aggregation of micelles and other structures due to hydrophobic interactions with the gel formation inhibitor. This allows the supplied gel formation inhibitor to exist more efficiently on the surface of the polypropylene particles, thus presumably resulting in an excellent gel-inhibiting effect. However, the present invention is not limited in any way by the validity of the presumed mechanism of action described above.

[0057] Furthermore, the reaction inhibitor may be present in a ratio of 0.3 to 5 molars, 0.6 to 4 molars, or 0.9 to 3 molars relative to the organoaluminum compound (B) supplied in the first step.

[0058] 4. Supply of gel formation inhibitor The gel formation inhibitor is supplied to the retained powder inside the reactor from an insert nozzle connected to the gas-phase fluidized bed polymerization reactor in at least one of the first or second steps, either diluted with an organic solvent such as hexane based on its viscosity and supply capacity, or supplied alone. By supplying the gel formation inhibitor into the retained powder inside the reactor through an insert nozzle that protrudes from the inner wall of the reactor into the internal space, the gel formation inhibitor is uniformly dispersed in the retained powder, thus providing an excellent gel formation suppression effect. In the present invention, the gel formation inhibitor is supplied into the reactor from an insert nozzle, eliminating the need to supply the gel formation inhibitor into the reactor as a mixed flow with liquefied propylene. Therefore, the manufacturing method of the present invention can be applied to a gas-phase fluidized bed polymerization reactor, which is a polymerization reactor that does not use liquefied propylene.

[0059] In order to uniformly disperse the gel formation inhibitor into the retained powder inside the reactor, it is desirable that most, ideally all, of the gel formation inhibitor discharged from the tip of the insert nozzle into the gas-phase fluidized bed polymerization reactor be scattered through the space inside the reactor without adhering to the inner wall of the reactor, and reach the retained powder on the fluidized bed directly. For these reasons, the arrangement of insert nozzles inside the reactor requires that there be sufficient distance between the inner wall of the reactor and the discharge port at the tip of the nozzle, thereby preventing the gel formation inhibitor from adhering to the inner wall of the reactor due to dripping from the nozzle tip.

[0060] To meet the above requirements, the present invention connects an insert nozzle having at least one discharge port to the straight body of a gas-phase fluidized bed polymerization reactor, and positions the discharge port located at the furthest tip of the insert nozzle such that the distance from the discharge port to the inner wall of the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is within the range of 12% to 88%, preferably 15% to 85%, and more preferably 18% to 82%, of the inner diameter of the cross-section, regardless of the distance from the discharge port to any other location on the inner circumference of the cross-section. Furthermore, if the insert nozzle has two or more discharge ports, it is preferable to position all of the discharge ports so that the distance from the discharge port to the inner wall of the reactor cross-section at the location of the discharge port falls within the above range across the entire inner circumference of the cross-section. By meeting the above conditions, the dispersibility of the gel formation inhibitor within the reactor is improved, and the gel formation inhibitor is uniformly dispersed in the retained powder without dripping onto the walls, thereby suppressing a decrease in catalytic activity and achieving an excellent gel formation suppression effect.

[0061] Here, "cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port" refers to the cross-section obtained by cutting the straight section of the gas-phase fluidized bed polymerization reactor in a direction perpendicular to the longitudinal central axis of the internal space of the gas-phase fluidized bed polymerization reactor, passing through the location of the insert nozzle's discharge port. If the insert nozzle has two or more discharge ports, a corresponding cross-section is specified for each discharge port. Furthermore, "the inner diameter of the cross-section of a gas-phase fluidized bed polymerization reactor" refers to the inner circumference diameter drawn by the boundary line between the inner wall visible in the cross-section of the gas-phase fluidized bed polymerization reactor and the internal space of the reactor. Furthermore, the "straight section of the reactor" refers to the part of the reactor body consisting of straight sides, or more precisely, the section of the reactor body that maintains a constant shape and internal diameter continuously along its longitudinal axis. The internal shape of this section is cylindrical with a constant diameter. Typically, the internal space of the straight section of a gas-phase fluidized bed polymerization reactor has a cylindrical shape, and its cross-section is perfectly circular.

[0062] Figure 2 is a cross-sectional view showing the insert nozzle 114 connected to the straight section of the first reactor 100 of the continuous vertical gas-phase fluidized bed polymerization reactor shown in Figure 1. Figure 3 is a perspective view corresponding to the cross-sectional view in Figure 2. In Figures 2 and 3, the straight body of the first reactor 100 is cylindrical, and the insert nozzle 114 is inserted into the cylindrical straight body at an angle such that the nozzle tip is upward relative to the direction of gravity. In Figure 3, the solid line portion of the insert nozzle 114 indicates that it is outside the first reactor 100, while the dotted line portion of the first reactor indicates that it protrudes into the internal space of the reactor. The insert nozzle 114 has one discharge port at its tip. In this case, the straight body of the first reactor 100 is cut in a direction perpendicular to the longitudinal central axis X of the internal space of the first reactor 100, and at a height that passes through point P0, where the discharge port of the insert nozzle 114 is located, thereby obtaining a cross-section A of the first reactor 100 at the location of the discharge port.

[0063] Figure 4 is a plan view of the cross-section A shown in Figures 2 and 3, viewed from directly above, illustrating an example of adjusting the position of the discharge port of the insert nozzle. Since the straight section of the first reactor 100 has a cylindrical shape, the shape of the cross section A is a perfect circle. In the cross section A, the inner wall of the first reactor 100 is represented by a line that delineates the inner circumference of the cross section A, the inner diameter of the cross section A is represented by R, and the intersection point of the longitudinal central axis X of the internal space of the first reactor 100 and the cross section A is represented by Y, and this intersection point Y is also the center point of the cross section A. Point P0 represents a candidate position for the discharge port provided at the tip of the insert nozzle 114. Point P1 represents the position that is the shortest distance from point P0, the location of the discharge port, to the inner circumference of cross-section A, and point P2 represents the position that is the longest distance from point P0, the location of the discharge port, to the inner circumference of cross-section A. Points P1 and P2 lie on the same straight line passing through the center point Y of cross-section A. Points P3 and P4 are arbitrary points on the inner circumference of cross-section A other than points P1 and P2. As a hypothetical example 1 based on Figure 4, if the shortest distance from the outlet to the inner circumference of cross-section A, i.e., the distance from point P0 to point P1, is set to 15% of the length of the inner diameter R of cross-section A, then the longest distance from point P0, the outlet, to the inner circumference of cross-section A, i.e., the distance from point P0 to point P2, will be 85% of the length of the inner diameter R of cross-section A. Also, the distance from point P0 to point P3, and the distance from point P0 to point P4, will both be greater than 15% but less than 85% of the inner diameter R of cross-section A. In this hypothetical example 1, the distance from the outlet of the insert nozzle to the inner wall at any position on the inner circumference of cross-section A of the reactor is also adjusted to be within the range of 12% to 88% of the length of the inner diameter R. As a hypothetical example 2 based on Figure 4, if the shortest distance from the outlet position to the inner circumference of cross-section A, i.e., the distance from point P0 to point P1, is set to 10% of the length of the inner diameter R of cross-section A, then the longest distance from point P0, which is the outlet position, to the inner circumference of cross-section A, i.e., the distance from point P0 to point P2, will be 90% of the length of the inner diameter R of cross-section A. In this hypothetical example 2, the outlet of the insert nozzle is not positioned within the range permitted in the present invention.

[0064] Figure 5 is a plan view of cross-section A shown in Figures 2 and 3, viewed from directly above. It is a diagram used to explain from a different perspective than Figure 4, illustrating an example of adjusting the position of the discharge port of the insert nozzle. In Figure 5, the statement, "The distance from point P0, which is the location of the discharge port at the tip of the insert nozzle 114, to the inner circumference of the cross-section A representing the inner wall of the first reactor 100 is adjusted so that the distance to any position on the inner circumference is within the range of 12% to 88% of the inner diameter of the cross-section A," can also be rephrased as, "The position of point P0, where the discharge port at the tip of the insert nozzle 114 is located, is adjusted to be inside or on the circumference of a concentric circle C, which has a center aligned with the center of the cross-section A and a circumference that is recessed by a width w corresponding to 12% of the inner diameter R of the cross-section A toward the center point Y from the inner circumference of the cross-section A," or, "The position of point P0, where the discharge port at the tip of the insert nozzle 114 is located, is adjusted to be inside or on the circumference of a concentric circle C, which has a center aligned with the center of the cross-section A and a radius r corresponding to 38% of the inner diameter R of the cross-section A." Here, the length of the radius r of the concentric circle C (a length corresponding to 38% of the inner diameter R of the cross section A) is obtained by subtracting the setback width w of the concentric circle from the inner circumference of the cross section A (a length corresponding to 12% of the inner diameter R of the cross section A) from the radius of the cross section A (a length corresponding to 50% of the inner diameter R of the cross section A). If the shape of the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is a perfect circle, as shown in cross-section A in Figures 2 and 3, the location of the discharge port provided at the tip of the insert nozzle 114 can be identified by rephrasing it as described above.

[0065] In the present invention, the shape of the "cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port" is not particularly limited and may be a rotationally symmetrical shape such as a perfect circle or an ellipse, or an irregular shape. If the cross-section of the straight body portion defining the inner diameter is not a perfect circle, the shortest diameter of the cross-sectional shape shall be taken as the inner diameter. From the viewpoint of ensuring design flexibility that allows for a wide area to be secured where the discharge port at the tip of the insert nozzle can be positioned, the cross-sectional shape of the reactor is preferably approximately circular, and particularly preferably circular. Figure 6 is a plan view illustrating an example of adjusting the position of the insert nozzle's discharge port by considering the shortest diameter of the cross-sectional shape as the inner diameter, since the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is not perfectly circular. In Figure 6, the cross-section A of the reactor has an elliptical shape with a minor axis of R1 and a major axis of R2, and the inner wall of the reactor is represented by a line that defines the inner circumference of cross-section A. In the example in Figure 6, the ratio of the length of the minor axis R1 to the length of the major axis R2 (R1:R2) is set to 1:1.5. The intersection point of the longitudinal central axis X of the reactor's internal space and cross-section A is represented by Y, and this intersection point Y is also the center point of cross-section A (the intersection point of the minor axis R1 and the major axis R2). Points P1a and P1b are the intersections of the minor axis (the axis that defines the minor axis R1) and the inner circumference of the ellipse. The distance from the center point Y of cross-section A to points P1a and P1b is the minor axis, and therefore corresponds to 50% of the length of the minor axis R1. On the other hand, points P2a and P2b are the intersections of the major axis (the axis that defines the major axis R2) and the inner circumference of the ellipse. The distance from the center point Y of cross-section A to points P2a and P2b is the major axis, and therefore corresponds to 50% of the length of the major axis R2. Points P0a, P0b, and P0c indicate candidate positions for the discharge port located at the tip of the insert nozzle. Point P0a is at the same position as the center point Y of the cross section A, point P0b is at a position shifted from the center point Y of the cross section A along the major axis in the direction of point P2b by a distance equivalent to 13% of the length of the minor axis R1, and point P0c is at a position shifted from the center point Y of the cross section A along the major axis in the direction of point P2b by a distance equivalent to 50% of the length of the minor axis R1.

[0066] As a hypothetical example 1 based on Figure 6, when the discharge port at the tip of the insert nozzle is positioned at point P0a (center point Y), the shortest distance from the discharge port to the inner circumference of cross-section A, i.e., the distance from point P0a to points P1a and P1b, is equal to the minor radius, so it is 50% of the length of the minor axis R1. On the other hand, the longest distance from the discharge port to the inner circumference of cross-section A, i.e., the distance from point P0a to points P2a and P2b, is equal to the major radius, and the ratio of the lengths of the minor axis R1 to the major axis R2 (R1:R2) is 1:1.5, so it is 75% of the length of the minor axis R1. In this hypothetical example 1, the distance from the discharge port of the insert nozzle to the inner wall at any position on the inner circumference of cross-section A of the reactor is adjusted to be within the range of 12% to 88% of the length of the minor axis R1, which is considered the inner diameter. As a hypothetical example 2 based on Figure 6, when the discharge port at the tip of the insert nozzle is located at point P0b, the shortest distance from the discharge port to the inner circumference of cross-section A is slightly shorter than the minor radius, which is approximately 50% of the length of the minor axis R1, and falls within the range of 12% to 88%. On the other hand, the longest distance from the discharge port to the inner circumference of cross-section A is the sum of the distance from the center point Y of cross-section A to point P0b (13% of the length of the minor axis R1) and the distance from the center point Y of cross-section A to point P2a, i.e., the major axis (75% of the length of the minor axis R1), and is therefore 88% of the length of the minor axis R1. In this hypothetical example 2 as well, the distance from the discharge port of the insert nozzle to the inner wall at any position on the inner circumference of cross-section A of the reactor is also adjusted to fall within the range of 12% to 88% of the length of the minor axis R1, which is considered the inner diameter. In hypothetical example 3 based on Figure 6, when the discharge port at the tip of the insert nozzle is positioned at point P0c, the shortest distance from the discharge port to the inner circumference of cross-section A is the distance from the center point Y of cross-section A to point P2b, i.e., the semi-major axis (75% of the length of the minor axis R1), minus the distance from the center point Y of cross-section A to point P0c (50% of the length of the minor axis R1). This is approximately 25% of the length of the minor axis R1, which falls within the range of 12% to 88%. However, in hypothetical example 3, the longest distance from the discharge port to the inner circumference of cross-section A is the sum of the distance from the center point Y of cross-section A to point P0c (50% of the length of the minor axis R1) and the distance from the center point Y of cross-section A to point P2a (75% of the length of the minor axis R1). This is 125% of the length of the minor axis R1, exceeding the upper limit of 88%. Therefore, unlike hypothetical examples 1 and 2, in hypothetical example 3, the discharge port of the insert nozzle is not positioned within the range permitted in the present invention.

[0067] According to hypothetical examples 1 to 3 in Figure 6, if the cross-section A of the reactor has an elliptical shape and the ratio of the lengths of the minor axis R1 to the major axis R2 (R1:R2) is set to 1:1.5, then even if the discharge port at the tip of the insert nozzle is positioned slightly offset from the center point Y of the cross-section A of the reactor (the intersection of the minor axis R1 and the major axis R2), it can be understood that the distance from the discharge port of the insert nozzle to the inner wall on the inner circumference of the cross-section A of the reactor can be within the range of 12% to 88% of the length of the minor axis R1, which is considered the inner diameter. Therefore, in this case, there is design freedom to select the position of the discharge port at the tip of the insert nozzle within a certain range. If the elliptical shape of the reactor cross-section A shown in Figure 6 becomes flatter, and the ratio of the lengths of the minor axis R1 to the major axis R2 (R1:R2) becomes 1:1.76, then the distance from the center point Y of the cross-section A to points P2a and P2b, i.e., the major axis, becomes 88% of the length of the minor axis R1. Only if the discharge port of the tip of the insert nozzle is positioned at the center point Y of the reactor cross-section A (the intersection of the minor axis R1 and the major axis R2), can the distance from the discharge port of the insert nozzle to the inner wall on the inner circumference of the reactor cross-section A be within the range of 12% to 88% of the length of the minor axis R1, which is considered the inner diameter. Furthermore, as the elliptical shape of the reactor cross-section A shown in Figure 6 becomes even more flattened, and the ratio of the lengths of the minor axis R1 to the major axis R2 (R1:R2) exceeds 1:1.76, it becomes impossible to keep the distance from the discharge port of the insert nozzle to the inner wall located on the inner circumference of the reactor cross-section A within the range of 12% to 88% of the length of the minor axis R1, which is considered the inner diameter. As described above, if the cross-sectional shape of the straight section of the gas-phase fluidized bed polymerization reactor is extremely far from a perfect circle, it becomes impossible to set the distance from the discharge port of the insert nozzle to the inner wall located on the inner circumference of the reactor's cross-section A within the range of 12% to 88% of the length of the minor axis R1, which is considered the inner diameter. However, typically, the internal space of the straight section of a gas-phase fluidized bed polymerization reactor has a cylindrical shape with a perfect circle in cross-section, taking into consideration the strength of the reactor and the uniformity of the polymerization reaction. Furthermore, even if the cross-section of the reactor is not a perfect circle, the internal space of the straight section of the reactor is designed to have a cylindrical shape with a cross-section that approximates a perfect circle. Therefore, if the reactor to which the insert nozzle is attached has a shape that is generally expected, the distance from the discharge port at the tip of the insert nozzle to the inner wall of the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port can be adjusted within a range of 12% to 88% of the length of the inner diameter or the minor axis considered to be the inner diameter of the cross-section, and no particular difficulty arises in making such adjustment.

[0068] To further address the requirement of maintaining a sufficient distance between the reactor inner wall and the nozzle tip discharge port, thereby preventing the gel formation inhibitor from adhering to the reactor inner wall due to dripping from the nozzle tip, it is preferable to set the horizontal angle (perpendicular to the direction of gravity) of the insert nozzle to an angle as close to a right angle as possible with respect to the inner wall of the gas-phase fluidized bed polymerization reactor. Specifically, the horizontal angle between the portion of the insert nozzle protruding into the reactor internal space and the inner wall of the gas-phase fluidized bed polymerization reactor is preferably 45 to 90 degrees, more preferably 60 to 90 degrees, even more preferably 75 to 90 degrees, and ideally 90 degrees. Furthermore, the vertical angle of the insert nozzle (parallel to the direction of gravity) may be set perpendicular to the inner wall of the gas-phase fluidized bed polymerization reactor, or it may be tilted at an appropriate angle so that the nozzle tip points upward or downward, in order to adjust the diffusion state of the gel formation inhibitor discharged from the insert nozzle. Here, the nozzle angle refers to the angle formed between the tangent plane that contacts the inner wall of the gas-phase fluidized bed polymerization reactor at the connection point between the gas-phase fluidized bed polymerization reactor and the insert nozzle, and the longitudinal axis of the portion of the insert nozzle that protrudes into the gas-phase fluidized bed polymerization reactor.

[0069] The gel formation inhibitor may be supplied to one or both of the reactors in the first and second steps, but it is preferable to supply it to at least the reactor in the second step, as this allows for a higher maintenance of catalytic activity.

[0070] When the gel formation inhibitor is supplied in a diluted state with an organic solvent due to its viscosity and supply capacity, it is preferable to appropriately select and use an inert hydrocarbon solvent as the organic solvent. As the hydrocarbon solvent, saturated aliphatic or aromatic hydrocarbons such as hexane, heptane, pentane, cyclohexane, benzene, and toluene can be used individually or in mixtures.

[0071] Furthermore, when diluting with an organic solvent, the concentration of the gel formation inhibitor in the organic solvent can be appropriately selected according to the viscosity of the solution at the temperature and the amount added. The concentration of the gel formation inhibitor may be 0.1 g to 100 g or 1 g to 50 g per liter of organic solvent.

[0072] 5. Supply of reaction inhibitors When supplying a reaction inhibitor, the gel formation inhibitor and the reaction inhibitor can be pre-mixed to form a mixed reaction inhibitor, which can then be supplied to the gel formation inhibitor supply line and delivered into the retained powder inside the reactor through an insert nozzle. Alternatively, the gel formation inhibitor and the reaction inhibitor can be supplied separately to the gel formation inhibitor supply line, where they can be mixed to form a mixed reaction inhibitor, which can then be delivered into the retained powder inside the reactor through an insert nozzle. The reaction inhibitor can also be supplied into the reactor from a gas supply line of a gas circulation system separate from the gel formation inhibitor supply line, or any combination of these supply routes may be used. From the standpoint of dispersibility, the reaction inhibitor may be supplied into the reactor from a gas supply line of a gas circulation system, separate from the gel formation inhibitor supply line.

[0073] 6. Propylene-based block copolymers produced The propylene-based block copolymer produced by the present invention allows for control of the melt flow rate (MFR) of the crystalline propylene polymer by using a molecular weight modifier such as hydrogen during the polymerization process in the propylene homopolymerization or copolymerization of propylene with other α-olefins produced in the first step. The MFR of the crystalline propylene polymer is set according to the molding method and application, but the MFR value (unit: g / 10 min) measured under measurement conditions of 230°C and a 2.16 kg load is usually 0.1 or higher, preferably 0.5 or higher, more preferably 1 or higher, and usually 1000 or lower, preferably 600 or lower, and more preferably 400 or lower. If the MFR is too low, the fluidity of the polymer decreases significantly, making molding difficult, and if it is too high, a decrease in tensile properties occurs.

[0074] In the second step, the intrinsic viscosity [η] of the amorphous propylene-α-olefin copolymer can be controlled by using a molecular weight modifier such as hydrogen during the polymerization process. From the standpoint of improving melt tension, flow marks, and product appearance by suppressing the number of gels, the intrinsic viscosity [η] of the amorphous propylene-α-olefin copolymer is preferably in the range of 3dL / g to 12dL / g, and more preferably in the range of 4dL / g to 11dL / g. Furthermore, from the standpoint of improving impact resistance and improving the product appearance by suppressing the number of gels, the α-olefin content in the amorphous propylene-α-olefin copolymer is preferably in the range of 10% to 90% by mass, and more preferably in the range of 20% to 80% by mass. If the α-olefin content is lower than this range, the amorphous nature is lost, which may impair the impact resistance of the product and is therefore undesirable. If the α-olefin content is higher than this range, the degree of compatibility with crystalline propylene decreases, which increases the number of gels and may impair the product appearance and is therefore undesirable.

[0075] Furthermore, from the viewpoint of suppressing gel formation, when the propylene-based block copolymer is considered to be 100% by mass, it is preferable that the propylene-α-olefin copolymer is 10% to 65% by mass and the crystalline propylene resin is 35% to 90% by mass, more preferably that the propylene-α-olefin copolymer is 12% to 62% by mass and the crystalline propylene resin is 38% to 88% by mass, and even more preferably that the propylene-α-olefin copolymer is 14% to 59% by mass and the crystalline propylene resin is 41% to 86% by mass. Furthermore, to improve the product appearance, when the propylene-based block copolymer is used as an injection-molded sheet with a thickness of 2 mm, the number of gels with a major axis of 300 μm or larger should be 500 per cm. 2 Preferably, the following: 300 pieces / cm 2 The following is more preferable: A method for forming the propylene-based block copolymer into an injection-molded sheet with a thickness of 2 mm can be, for example, the method described in the examples below. [Examples]

[0076] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. The methods for measuring each physical property value in the present invention are shown below. [Measurement of various physical properties] (1) MFR The propylene polymers obtained in the examples were evaluated under conditions compliant with JIS K7210 (230°C, 2.16 kg load).

[0077] (2) Method for analyzing propylene-based block copolymers The ratio of the propylene-ethylene copolymer portion (Wc), ethylene content (Gv), and intrinsic viscosity (η) in the propylene-based block copolymer were measured according to the method described in paragraphs 0082 to 0086 of Patent Document 2 (Japanese Patent Application Publication No. 2022-014443), using the following apparatus and conditions.

[0078] (2-1) Analytical equipment to be used (i) Cross sorting device Dia Instruments CFC T-100 (abbreviated as CFC) (ii) Fourier transform infrared absorption spectroscopy FT-IR, PerkinElmer 1760X The fixed-wavelength infrared spectrophotometer that was attached as the detector for the CFC was removed and replaced with an FT-IR, which was then used as the detector. The transfer line from the outlet of the solution eluted from the CFC to the FT-IR was 1 m long and maintained at 140°C throughout the measurement. The flow cell attached to the FT-IR had an optical path length of 1 mm and an optical path width of 5 mmφ and was also maintained at 140°C throughout the measurement. (iii) Gel permeation chromatography (GPC) For the GPC column in the post-CFC stage, three Showa Denko AD806MS columns are used, connected in series.

[0079] (2-2) Measurement conditions for CFCs (i) Solvent: Orthodichlorobenzene (ODCB) (ii) Sample concentration: 4 mg / mL (iii) Injection volume: 0.4mL (iv) Crystallization: Cool the temperature from 140°C to 40°C over approximately 40 minutes. (v) Separation method: During temperature-induced elution fractionation, the fractionation temperatures are set to 40, 100, and 140°C, resulting in a total of three fractions. The elution ratios (in mass%) of the components that elute below 40°C (Fraction 1), those that elute between 40 and 100°C (Fraction 2), and those that elute between 100 and 140°C (Fraction 3) are defined as W40, W100, and W140, respectively. W40 + W100 + W140 = 100. Each of the separated fractions is then automatically transported to the FT-IR analyzer. (vi) Solvent flow rate during elution: 1 mL / min

[0080] (2-3) FT-IR measurement conditions After the elution of the sample solution from the GPC following the CFC is initiated, FT-IR measurements are performed under the following conditions, and GPC-IR data is collected for each of the fractions 1 to 3 described above. (i) Detector: MCT (ii) Resolution: 8cm -1 (iii) Measurement interval: 0.2 minutes (12 seconds) (iv) Number of cumulative measurements per measurement: 15

[0081] (2-4) Post-processing and analysis of measurement results The amount of eluted components and molecular weight distribution at each temperature were obtained by FT-IR at 2945 cm². -1 The absorbance is used as a chromatogram to determine the elution amount. The elution amount is normalized so that the sum of the elution amounts of each component equals 100%. The conversion from retention capacity to molecular weight is performed using a calibration curve prepared in advance using standard polystyrene. The standard polystyrene used is the following brand, manufactured by Tosoh Corporation. F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000. Calibration curves are created by injecting 0.4 mL of solutions, each containing 0.5 mg / mL of BHT, into an ODCB (containing 0.5 mg / mL of BHT). The calibration curves are approximated using a cubic equation obtained by the least squares method. For conversion to molecular weight, a general calibration curve is used, referring to "Size Exclusion Chromatography" by Sadao Mori (Kyoritsu Shuppan). The viscosity formula used is [η] = K × M α The following values ​​are used for ).

[0082] (i) When creating a calibration curve using standard polystyrene K=0.000138, α=0.70 (ii) When measuring samples of propylene-based block copolymers K=0.000103, α=0.78 The ethylene content distribution of each eluted component (distribution of ethylene content along the molecular weight axis) is obtained by FT-IR at 2956 cm². -1 Absorbance and 2927cm² -1 Using the ratio of absorbance, polyethylene, polypropylene and 13 The ethylene content is determined by converting it to mass %) using a calibration curve prepared in advance with ethylene-propylene rubber (EPR) and mixtures thereof, whose ethylene content is known by 13C-NMR measurement or the like.

[0083] (2-5) Ratio of the propylene-ethylene random copolymer portion (Wc) In the present invention, the ratio (Wc) of the propylene-ethylene random copolymer portion in the propylene-based block copolymer is theoretically defined by the following formula (I) and can be determined by the following procedure. Wc (mass%)=W 40 ×A 40 / B 40 +W 100 ×A 100 / B 100 …(I) In equation (I), W40 , W 100 This represents the elution rate (unit: mass%) in each of the above-mentioned fractions, and A 40 , A 100 is, W 40 , W 100 This is the actual average ethylene content (unit: mass%) in each corresponding fraction, and B 40 B 100 This represents the ethylene content (unit: mass%) of the propylene-ethylene random copolymer portion contained in each fraction. For the meaning of formula (I), please refer to paragraph 0083 of Patent Document 2 (Japanese Patent Publication No. 2022-014443). 40 , A 100 B 40 B 100 For the significance of this, please refer to paragraphs 0084-0085 of Patent Document 2, and for the significance of setting the above three types of separation temperatures, please refer to paragraph 0086 of Patent Document 2.

[0084] (i) The average ethylene content corresponding to fractions 1 and 2 obtained by CFC measurement is A 40 , A 100 (All units are in mass percent). The method for calculating the average ethylene content will be described later. (ii) The ethylene content corresponding to the peak position in the differential molecular weight distribution curve of fraction 1 is B 40 (The unit is mass%). For fraction 2, in this invention, B 100 Let's set it to =100. (iii) For the reasons stated above, the ratio (Wc) of the propylene-ethylene random copolymer portion is determined according to the following formula. Wc (mass%)=W 40 ×A 40 / B 40 +W 100 ×A 100 / 100 …(II) Here, B 40 And the average ethylene content A of each fraction 1 and 2 obtained by CFC measurement 40 , A 100 This can be found as follows: The ethylene content corresponding to the peak position of the differential molecular weight distribution curve is B 40 This is the result. In addition, the sum of the products of the mass percentage of each data point and the ethylene content of each data point, which are captured as data points during measurement, is the average ethylene content A of fraction 1. 40 This is the result. Average ethylene content A of fraction 2. 100 We can find the same result.

[0085] (2-6) Ethylene content of the propylene-ethylene random copolymer portion The ethylene content of the propylene-ethylene random copolymer portion in the propylene-based block copolymer of the present invention can be determined using the values ​​described above and the following formula. Ethylene content (mass%) of the propylene-ethylene random copolymer portion = (W 40 ×A 40 +W 100 ×A 100 ) / Wc However, Wc is the ratio (mass%) of the propylene-ethylene random copolymer portion determined earlier.

[0086] (2-7) Measurement of intrinsic viscosity The intrinsic viscosity [η]p of the crystalline propylene polymer portion and the propylene-ethylene random copolymer portion in the propylene-based block copolymer of the present invention is measured at a temperature of 135°C using an Ubbelohde viscometer with decalin as the solvent. First, after the polymerization of the crystalline propylene polymer is complete, a portion is sampled from the polymerization tank and its intrinsic viscosity [η]p is measured. Next, after polymerization of the crystalline propylene polymer, the intrinsic viscosity [η]F of the final polymer (F) obtained by polymerization of the propylene-ethylene random copolymer is measured. [η]c is determined from the following relationship. [η]F=(100-Wc) / 100×[η]p+Wc / 100×[η]c

[0087] (3) Method for evaluating gels 100 parts by mass of propylene block copolymer granules were dry-blended with 0.5 parts of blue pigment. This mixture was then molded using a Niigata Iron Works NN30-H4000 injection molding machine with a clamping pressure of 30 tons and a mold with a 2 mm wide film gate at a molding temperature of 240°C and a primary injection pressure of 55 kgf / cm². 2 , Secondary pressure=45kgf / cm 2 A 50mm square x 0.05mm thick injection-molded sheet is formed using this method. For each of the 10 molded sheets, the size of the gel is measured and the number of gels is counted. Of all the counted gels, those with a major axis of 50 μm or more are considered "total gels" and their number is converted to a number per square centimeter. Here, the major axis refers to the longest length of the straight line connecting two points on the outer circumference of the observed gel. Gels with a major axis of 300 μm or more are classified as "large gels" and evaluated by converting the number of gels per square centimeter.

[0088] (4) Qualitative method for compounds represented by general formula (1) in propylene-based block copolymers 5.0 g of a propylene block copolymer sample is mixed with 70 ml of acetonitrile, and the components are ultrasonically extracted at 30°C for 1 hour. The acetonitrile solution is filtered through filter paper (ADVANTEC 5C filter paper), and the filtrate is collected. The acetonitrile is removed by evaporating and vacuum drying (25°C for 1 hour). Then, 1.0 ml of orthodichlorobenzene / deuterated bromide benzene = 2 / 1 (volume ratio) is added to the dried filtrate to prepare a solution. This solution is placed in an NMR sample tube, and NMR measurement is performed. 1 The presence or absence of a peak representing the polyoxyethylene structure, detected at 3.8–3.2 ppm in the 1H-NMR spectrum, is used to confirm the presence or absence of the compound represented by general formula (1). Furthermore, to determine whether or not the gel formation inhibitor supplied from the insert nozzle dripped, powder adhering to the wall surface around the insert nozzle after manufacturing was collected and subjected to the same NMR analysis as described above. As a result, using the peak intensity derived from the polyoxyethylene structure detected from powder impregnated with 300 ppm of the compounds represented by general formula (1), namely Pluronic® 31R1 and Pluronic® 17R2 (gel formation inhibitors), in 100 g of the propylene-based block copolymer manufactured in Comparative Example 1, samples showing a peak intensity 50 times or more at a similar mass ppm impregnation amount were judged to have excessive dripping of the gel formation inhibitor. <Equipment> JNM-ECS400 FT NMR manufactured by JEOL RESONANCE <probe>: 5mm FG / TH Auto-Tune Probe <Measurement temperature> Room temperature < 1 H-NMR measurement: Pre-saturation elimination of solvent, flip angle = 45°, spin on, flip angle = 45°, pulse interval = 9.8 seconds, number of integrations = 256 times

[0089] [Examples of catalyst manufacturing] (1) Preparation of solid catalyst components for propylene polymerization Preparation of Solid Components: A 10 L autoclave equipped with a stirring device was thoroughly purged with nitrogen, and 2 L of purified toluene was introduced. 200 g of Mg(OEt)2 and 1 L of TiCl4 were added at room temperature. The temperature was raised to 90°C, and 40 ml of di-n-butyl phthalate and 10 ml of diethyl phthalate were introduced. The temperature was then raised to 110°C, and the reaction was carried out for 3 hours. The reaction product was thoroughly washed with purified toluene. Next, purified toluene was introduced to adjust the total volume to 2 L. 1 L of TiCl4 was added at room temperature, and the temperature was raised to 110°C, and the reaction was carried out for 2 hours. The reaction product was thoroughly washed with purified toluene. Next, purified toluene was introduced to adjust the total volume to 2 L. 1 L of TiCl4 was added at room temperature, and the temperature was raised to 110°C, and the reaction was carried out for 2 hours. The reaction product was thoroughly washed with purified toluene. Furthermore, toluene was replaced with n-heptane using purified n-heptane to obtain a slurry of solid components. A portion of this slurry was sampled, dried, and analyzed, and the Ti content of the solid components was found to be 1.7% by mass. Next, a 20 L autoclave equipped with a stirring device was thoroughly purged with nitrogen, and 100 g (0.036 mol Ti) of the above solid component slurry was introduced as the solid component. Purified n-heptane was introduced to adjust the concentration of the solid component to 25 g / L. 50 ml of SiCl4 was added, and the reaction was carried out at 90°C for 1 hour. After thoroughly washing the reaction product with purified n-heptane, purified n-heptane was introduced to adjust the liquid level to 4 L. 25 ml of [CH2=CH]2-SiMe2, 18 ml of (i-Pr)2Si(OMe)2, and 40 g (0.35 mol) of dilution of triethylaluminum in n-heptane were added, and the reaction was carried out at 40°C for 2 hours. The reaction product was thoroughly washed with purified n-heptane. When a portion of the obtained slurry was sampled, dried, and analyzed, the solid components contained 1.2 mass% Ti and 6.7 mass% (i-Pr)2Si(OMe)2.

[0090] (2) Preparation of prepolymerization catalyst for propylene polymerization Using 100 g (0.019 mol Ti) of the solid component obtained above, prepolymerization was carried out according to the following procedure. Purified n-heptane was introduced into the slurry to adjust the concentration of the solid component to 20 g / L. After cooling the slurry to 10°C, 15 g (0.132 mol) of a dilution of triethylaluminum in n-heptane was added as triethylaluminum, and 280 g of propylene was supplied over 4 hours. After the supply of propylene was completed, the reaction was continued for another 30 minutes. Next, the gas phase was thoroughly replaced with nitrogen, and the reaction product was thoroughly washed with purified n-heptane. The obtained slurry was removed from the autoclave and vacuum dried to obtain a solid catalyst component. Analysis of this solid catalyst component revealed that it contained 2.0 g of polypropylene per 1 g of solid component, and the portion of this solid catalyst component excluding polypropylene contained 1.2 mass% Ti and 6.4 mass% (i-Pr)2Si(OMe)2.

[0091] (Example 1) Figure 1 is a schematic diagram illustrating an example of the layout of a continuous vertical gas-phase reactor. The procedure performed will be explained with reference to Figure 1. Polymerization was carried out using a continuous reactor consisting of two fluidized bed reactors, each with a total internal volume of 2000 L and a perfectly circular cross-sectional shape of the straight body, connected together. In reactor 100, the polymerization temperature was 65°C, the propylene partial pressure was 1.8 MPa (absolute pressure), and hydrogen was supplied as a molecular weight control agent at a hydrogen / propylene molar ratio of 0.097. Gas propylene was continuously supplied from pipe 106 and hydrogen from pipe 108. At the same time, the catalyst from the catalyst production example was supplied from pipe 101 at a rate of 0.85 g / hr to achieve a polymerization rate of 16.7 kg / hr for the propylene polymer, and a 7% by mass n-hexane diluted solution of triethylaluminum was continuously supplied from pipe 110 at a rate of 100 mmol / hr. The production efficiency of crystalline PP per gram of catalyst was 20,000 g / g. The gel formation inhibitor, polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1, manufactured by BASF, number average molecular weight approximately 3100, p+r=48, q=9), was supplied to the powder held in the first reactor from an insert nozzle 114 having a single discharge port at its tip, using a 10 g / L n-hexane diluted solution, so that the polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer was present at a concentration of 49 ppm relative to the total amount of propylene-based block copolymer powder produced. The insert nozzle 114 was inserted and fixed perpendicularly to the inner wall of the reactor, and the shortest distance from the tip outlet to the inner wall of the reactor's cross-section at the location of the outlet was 20% of the inner diameter of the cross-section. Furthermore, since the cross-sectional shape was a perfect circle and the shortest distance from the tip outlet to the inner wall of the reactor's cross-section was 20%, the longest distance from the tip outlet to the inner wall of the reactor's cross-section was calculated to be 80% of the inner diameter of the cross-section. From these calculation results, it was confirmed that the distance from the tip outlet to the inner wall of the reactor's cross-section was between 20% and 80% of the inner diameter of the cross-section throughout the entire inner circumference of the cross-section. The polypropylene polymer powder polymerized in the first reactor was continuously withdrawn from the powder discharge case 111 at a rate of 16.7 kg / hr so ​​as to maintain a powder volume of 45 kg in the reactor, and then continuously transferred to the second reactor 200 through the resin transfer case 201.

[0092] In the second reactor 200, the polymerization temperature was set to 70°C and the monomer pressure to 1.57 MPa (propylene + ethylene). To achieve a molar ratio of ethylene / propylene of propylene and ethylene, and a molar ratio of hydrogen / propylene of 0.0037, gaseous propylene was continuously supplied from pipe 206, gaseous ethylene from pipe 207, and hydrogen from pipe 208. In addition, ethanol, which acts as a reaction inhibitor, was supplied from pipe 209 using a 20 g / L n-hexane dilution solution, in a ratio of 16 parts by mass of gel formation inhibitor supplied to the first reactor for every 100 parts by mass of ethanol. The propylene-based block copolymer powder polymerized in the second reactor was continuously withdrawn from pipe 210 at a rate of 20.8 kg / hr to maintain a powder volume of 50 kg in the reactor, and the reaction was stopped by supplying moisture-containing nitrogen gas to produce propylene-based block copolymer-1. The production efficiency of propylene-based block copolymer per gram of catalyst was 24,500 g / g.

[0093] Analysis of the obtained propylene-based block copolymer revealed that MFR = 35 g / 10 min, the ratio of the propylene-ethylene copolymer portion (Wc) = 21% by mass, and the ethylene content of the propylene-ethylene copolymer portion = 41% by mass. 1 A peak originating from polyoxyethylene chains was observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, after manufacturing, the powder adhering to the wall surface around the insert nozzle was collected and subjected to the same NMR analysis as described above. The results showed that, compared to 100g of the propylene-based block copolymer manufactured in Comparative Example 1, the peak intensity was 8.6 times higher at the same mass ppm impregnation amount compared to the peak intensity derived from the polyoxyethylene structure detected from the powder impregnated with the gel formation inhibitor polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1). Therefore, it was determined that there was no leakage of the gel formation inhibitor.

[0094] (Example 2) The procedure performed will be explained with reference to Figure 1. Polymerization was carried out using a continuous reactor consisting of two fluidized bed reactors with an internal volume of 2000 L connected together. In reactor 100, the polymerization temperature was 65°C, the propylene partial pressure was 1.8 MPa (absolute pressure), and hydrogen was supplied as a molecular weight control agent at a hydrogen / propylene molar ratio of 0.097. Gas propylene was continuously supplied from pipe 106 and hydrogen from pipe 108. At the same time, the catalyst from the catalyst production example was supplied from pipe 101 at a rate of 0.75 g / hr so ​​that the polymerization rate of the propylene polymer was 16.7 kg / hr, and a 7 mass% n-hexane diluted solution of triethylaluminum was continuously supplied from pipe 110 at a rate of 100 mmol / hr. The production efficiency of crystalline PP per gram of catalyst was 22,300 g / g. The polypropylene polymer powder polymerized in the first reactor was continuously withdrawn from the powder discharge case 111 at a rate of 16.7 kg / hr so ​​that the amount of powder in the reactor was 45 kg, and then continuously transferred to the second reactor 200 through the resin transfer case 201.

[0095] In reactor 200, the polymerization temperature was set to 70°C and the monomer pressure to 1.57 MPa (propylene + ethylene). To ensure that the molar ratio of propylene to ethylene (ethylene / propylene) was 0.57 and the molar ratio of hydrogen to propylene (hydrogen / propylene) as a molecular weight control agent was 0.0037, the raw materials were continuously supplied: gaseous propylene from pipe 206, gaseous ethylene from pipe 207, and hydrogen from pipe 208. The gel formation inhibitor, polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1), was supplied to the powder held in the first reactor from an insert nozzle 213 having a single discharge port at its tip, using a 30 g / L n-hexane diluted solution, so that the concentration of polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1) was 296 ppm relative to the total amount of propylene-based block copolymer powder produced. The insert nozzle 213 was inserted and fixed perpendicularly to the inner wall of the reactor, and the shortest distance from the tip outlet to the inner wall of the reactor's cross-section at the location of the outlet was 20% of the inner diameter of the cross-section. Furthermore, since the cross-sectional shape was a perfect circle and the shortest distance from the tip outlet to the inner wall of the reactor's cross-section was 20%, the longest distance from the tip outlet to the inner wall of the reactor's cross-section was calculated to be 80% of the inner diameter of the cross-section. From these calculation results, it was confirmed that the distance from the tip outlet to the inner wall of the reactor's cross-section was between 20% and 80% of the inner diameter of the cross-section throughout the entire inner circumference of the cross-section. Furthermore, the reaction inhibitor, ethanol, was supplied from piping 209 using a 20 g / L n-hexane dilution solution, in a ratio of 120 parts by mass of gel formation inhibitor supplied to the first reactor for every 100 parts by mass of ethanol. The propylene-based block copolymer powder polymerized in the second reactor was continuously withdrawn from pipe 210 at a rate of 20.6 kg / hr to maintain a powder volume of 50 kg in the reactor, and the reaction was stopped by supplying moisture-containing nitrogen gas to produce propylene-based block copolymer-2. The production efficiency of propylene-based block copolymer per gram of catalyst was 27,500 g / g.

[0096] Analysis of the obtained propylene-based block copolymer revealed that MFR = 36 g / 10 min, the ratio of the propylene-ethylene copolymer portion (Wc) = 21% by mass, and the ethylene content of the propylene-ethylene copolymer portion = 41% by mass. 1 A peak originating from polyoxyethylene chains was observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, after manufacturing, the powder adhering to the wall surface around the insert nozzle was collected and subjected to the same NMR analysis as described above. The results showed that, compared to 100g of the propylene-based block copolymer manufactured in Comparative Example 1, the peak intensity was 10.7 times higher at the same mass ppm impregnation amount compared to the peak intensity derived from the polyoxyethylene structure detected from the powder impregnated with the gel formation inhibitor polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1). Therefore, it was determined that there was no leakage of the gel formation inhibitor.

[0097] (Example 3) In Example 2, propylene-based block copolymer-3 was produced in the same manner as in Example 2, except that the shortest distance from the discharge port at the nozzle tip of the insert nozzle 213 connected to the reactor in the second step to the inner wall of the reactor cross-section at the location of the discharge port was set to 50% of the inner diameter of the cross-section. Since the cross-sectional shape is a perfect circle and the shortest distance from the tip outlet to the inner wall of the reactor's cross-section is 50%, the longest distance from the tip outlet to the inner wall of the reactor's cross-section was calculated to be 50% of the inner diameter of the cross-section. From this calculation result, it was confirmed that the distance from the tip outlet to the inner wall of the reactor's cross-section is 50% of the inner diameter of the cross-section throughout the entire inner circumference of the cross-section. Analysis of the obtained propylene-based block copolymer revealed that the acetonitrile extract 1 A peak originating from polyoxyethylene chains was observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, after manufacturing, the powder adhering to the wall surface around the insert nozzle was collected and subjected to the same NMR analysis as described above. The results showed that, compared to 100g of the propylene-based block copolymer manufactured in Comparative Example 1, the peak intensity was 7.5 times higher at the same mass ppm impregnation amount compared to the peak intensity derived from the polyoxyethylene structure detected from the powder impregnated with the gel formation inhibitor polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1). Therefore, it was determined that there was no leakage of the gel formation inhibitor.

[0098] (Example 4) In Example 2, the gel formation inhibitor supplied to the second reactor was changed to a polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 17R2, manufactured by BASF, number average molecular weight approximately 2200, p+r=30, q=17), and the propylene-based block copolymer-4 was produced in the same manner as in Example 2, except that it was used as a 30 g / L n-hexane diluted solution. Analysis of the obtained propylene-based block copolymer revealed that the acetonitrile extract 1 A peak originating from polyoxyethylene chains was observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, after manufacturing, the powder adhering to the wall surface around the insert nozzle was collected and subjected to the same NMR analysis as described above. The results showed that, compared to 100g of the propylene-based block copolymer manufactured in Comparative Example 1, the peak intensity was 12.8 times higher at the same mass ppm impregnation amount compared to the peak intensity derived from the polyoxyethylene structure detected from the powder impregnated with the gel formation inhibitor polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 17R2). Therefore, it was determined that there was no leakage of the gel formation inhibitor.

[0099] (Comparative Example 1) In Example 2, propylene-based block copolymer-C1 was produced in the same manner as in Example 2, except that the gel formation inhibitor was not supplied to the second reactor. Analysis of the obtained propylene-based block copolymer revealed that the acetonitrile extract 1 No peaks originating from polyoxyethylene chains were observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, when powder adhering to the wall surface around the insert nozzle was collected after manufacturing and subjected to the same NMR analysis as described above, no peaks originating from the polyoxyethylene structure were observed.

[0100] (Comparative Example 2) In Example 1, propylene-based block copolymer-C2 was produced in the same manner as in Example 1, except that the shortest distance from the discharge port at the nozzle tip of the insert nozzle 114 connected to the reactor in the first step to the inner wall of the reactor cross-section at the location of the discharge port was set to 10% of the inner diameter of the cross-section. Analysis of the obtained propylene-based block copolymer revealed that the acetonitrile extract 1 A peak originating from polyoxyethylene chains was observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, after manufacturing, the powder adhering to the wall surface around the insert nozzle was collected and subjected to the same NMR analysis as described above. The results showed that, compared to 100g of the propylene-based block copolymer manufactured in Comparative Example 1, the peak intensity was 51.4 times higher at the same mass ppm impregnation amount compared to the peak intensity derived from the polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1) detected from the powder impregnated with the same mass ppm impregnation amount. Therefore, it was determined that there was leakage of the gel formation inhibitor.

[0101] (Comparative Example 3) In Example 2, propylene-based block copolymer-C3 was produced in the same manner as in Example 2, except that the shortest distance from the discharge port at the nozzle tip of the insert nozzle 213 connected to the reactor in the second step to the inner wall of the reactor cross-section at the location of the discharge port was set to 0% of the inner diameter of the cross-section. Analysis of the obtained propylene-based block copolymer revealed that the acetonitrile extract 1 A peak originating from polyoxyethylene chains was observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, after manufacturing, the powder adhering to the wall surface around the insert nozzle was collected and subjected to the same NMR analysis as described above. The results showed that, compared to 100g of the propylene-based block copolymer manufactured in Comparative Example 1, the peak intensity was 128.4 times higher at the same mass ppm impregnation amount compared to the peak intensity derived from the polyoxyethylene structure detected from the powder impregnated with the gel formation inhibitor polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1). Therefore, it was determined that there was leakage of the gel formation inhibitor.

[0102] (Comparative Example 4) In Example 2, propylene-based block copolymer-C4 was produced in the same manner as in Example 2, except that the shortest distance from the discharge port at the nozzle tip of the insert nozzle 213 connected to the reactor in the second step to the inner wall of the reactor cross-section at the location of the discharge port was set to 10% of the inner diameter of the cross-section. Analysis of the obtained propylene-based block copolymer revealed that the acetonitrile extract 1 A peak originating from polyoxyethylene chains was observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, after manufacturing, the powder adhering to the wall surface around the insert nozzle was collected and subjected to the same NMR analysis as described above. The results showed that, compared to 100g of the propylene-based block copolymer manufactured in Comparative Example 1, the peak intensity was 64.2 times higher at the same mass ppm impregnation amount compared to the peak intensity derived from the polyoxyethylene structure detected from the powder impregnated with the gel formation inhibitor polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 31R1). Therefore, it was determined that there was leakage of the gel formation inhibitor.

[0103] (Comparative Example 5) In Example 4, propylene-based block copolymer-C5 was produced in the same manner as in Example 4, except that the shortest distance from the discharge port at the nozzle tip of the insert nozzle 213 connected to the reactor in the second step to the inner wall of the reactor cross-section at the location of the discharge port was set to 10% of the inner diameter of the cross-section. Analysis of the obtained propylene-based block copolymer revealed that the acetonitrile extract 1 A peak originating from polyoxyethylene chains was observed in the 1H-NMR spectrum at 3.8–3.2 ppm. Furthermore, after manufacturing, powder adhering to the wall surface around the insert nozzle was collected and subjected to the same NMR analysis as described above. The results showed that, compared to 100g of the propylene-based block copolymer manufactured in Comparative Example 1, the peak intensity was 77.0 times higher at the same mass ppm impregnation amount compared to the peak intensity derived from the polyoxyethylene structure detected from the powder impregnated with the gel formation inhibitor polyoxypropylene-polyoxyethylene-polyoxypropylene copolymer (Pluronic® 17R2). Therefore, it was determined that there was leakage of the gel formation inhibitor.

[0104] [Granulation process] For each of the propylene-based block polymers obtained in the above examples and comparative examples, add 0.1 parts by mass of 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (manufactured by Japan Scitec Industries Co., Ltd., trade name: Cyanox 1790) and 0.09 parts by mass of tris(2,4-di-t-butylphenyl) phosphite (manufactured by Ciba-Geigy, trade name: Irgaphos 168) as antioxidants to 100 parts by mass of each propylene-based block polymer obtained in the above examples and comparative examples. 0.05 parts by mass of 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (manufactured by ADEKA Corporation, trade name: Adekastab PEP-36), 0.09 parts by mass of N,N-bis(octadecyl)hydroxylamine (manufactured by Ciba-Geigy, trade name: Ilgastab FS042), and 0.03 parts by mass of calcium stearate as a neutralizing agent were added and mixed and blended for 5 minutes in a super mixer (manufactured by Kawada Seisakusho). Using the obtained blend, granules of a propylene-based block copolymer were obtained by underwater cut granulation under the following apparatus and conditions. Mixing extruder: 110mm inner diameter, single-screw extruder Die: TiC, φ2.5mm, 20 holes, heat channel type Cutter blade: TiC, 4 blades, 50° scoop angle Granulation processing rate: 200 kg / hr Screen pack filter: None

[0105] The polymerization and evaluation results are shown in Tables 1 and 2. In the tables, "mr" represents the molar ratio.

[0106] [Table 1]

[0107] [Table 2]

[0108] The results from Comparative Examples 1 and 2-5 show that even with similar amounts of reaction inhibitors, the absence of a gel formation inhibitor results in a lower gel deactivation effect and a very large amount of large gels. To reduce gel formation without a gel formation inhibitor, one could consider supplying an even larger amount of reaction inhibitor, but this would significantly reduce the production efficiency in the second reactor, making it impossible to reach the target propylene-ethylene copolymer content and therefore impractical. Furthermore, considering the results of Example 2 and Comparative Example 4, and the results of Example 4 and Comparative Example 5, it is considered that even if the molecular weight of the gel formation inhibitor is different, a similar polyethylene glycol structure can be expected to provide a gel deactivation effect. Furthermore, the results from Comparative Examples 2-5 show that, despite supplying a sufficient amount of gel formation inhibitor relative to the production rate, there was more gel and a large amount of dripping of the gel formation inhibitor compared to Examples 1-4. It is thought that the gel formation inhibitor was not fully effective due to poor dispersion of the powder in the reactor. In contrast, Examples 1 to 4 demonstrate that the gel formation inhibitor is fed into the retained powder inside the reactor from an insert nozzle connected to the gas-phase fluidized bed polymerization reactor in the first or second step, and since the insert nozzle has an insert length of 12% to 88% of the inner diameter of the straight section of the gas-phase fluidized bed polymerization reactor, the gel formation inhibitor is uniformly dispersed in the retained powder without dripping onto the wall surface. This shows that propylene-ethylene copolymers can be produced in a multi-stage continuous polymerization method with high catalytic efficiency while reducing gel formation without excessively increasing the number of reactors. [Explanation of Symbols]

[0109] 100 Reactor No. 1 101 Catalyst component supply piping 102 Gas Dispersion Plate 103 Cycle gas extraction piping 104-cycle gas compressor 105 Cycle Gas Cooler 106 Gas propylene supply piping 107 Gas ethylene supply piping 108 Hydrogen supply piping 109 External electron donor supply piping 110 Organic aluminum supply piping 111 Powder Discharge Case 112 Gel formation inhibitor supply piping 113 Valve 114 Insert Nozzle 200 Reactor No. 2 201 Resin Transfer Case 202 Gas Dispersion Plate 203 Cycle gas extraction piping 204-cycle gas compressor 205 Cycle Gas Cooler 206 Gas propylene supply piping 207 Gas ethylene supply piping 208 Hydrogen supply piping 209 Reaction inhibitor supply piping 210 Polymer extraction piping 211 Gel formation inhibitor supply piping 212 Valves 213 Insert Nozzle X Longitudinal axis A Cross-section of the reactor at the location of the discharge port. Y is the intersection of the longitudinal central axis X and the cross-section A. R Inner diameter of cross-section A Point P0 is the location where the discharge port of the insert nozzle is located. Points P1, P2, P3, and P4 are points located on the inner circumference of cross-section A. C Concentric circles w The recession width of the inner circumference of the concentric circles r Radius of concentric circles R1 is the minor axis of the cross-section A. R2 Major axis of cross-section A Points P0a, P0b, and P0c are the locations where the discharge port of the insert nozzle is located. Points P1a, P1b, P2a, and P2b are points located on the inner circumference of cross-section A.< / probe>

Claims

1. A method for producing a propylene-based block copolymer, comprising a multi-step continuous polymerization including a first step and a second step, using a gas-phase fluidized bed polymerization reactor in the presence of an olefin polymerization catalyst, In at least one of the first and second steps, an insert nozzle having at least one discharge port is connected to the straight body of the gas-phase fluidized bed polymerization reactor, and the distance from the discharge port located at the furthest tip of the insert nozzle to the inner wall of the cross-section of the gas-phase fluidized bed polymerization reactor at the location of the discharge port is within the range of 12% to 88% of the inner diameter of the cross-section, for any distance from the discharge port to the inner wall at any position on the inner circumference of the cross-section. A method for producing a propylene-based block copolymer, comprising supplying a gel formation inhibitor, which is a compound represented by the following general formula (1), from an insert nozzle into the retained powder inside the reactor. [General formula (1)] HO-[CH] ２ -CH(CH ３ )-O] ｐ -[CH ２ -CH ２ -O] ｑ -[CH ２ -CH(CH ３ )-O] ｒ -R １ (In general formula (1), p, q, and r are each independent integers from 1 to 60, and R １ (This represents a hydrogen atom or a hydrocarbon group having 1 to 25 carbon atoms.)

2. The method for producing a propylene-based block copolymer according to claim 1, wherein the gel formation inhibitor is supplied in a ratio of 0.001% by mass to 0.1% by mass relative to the amount of propylene-based block copolymer produced.

3. Furthermore, the method for producing a propylene-based block copolymer according to claim 1 or 2, wherein a reaction inhibitor represented by the following general formula (2) is supplied to the retained powder inside the reactor. [General formula (2)] HO-R ２ (In general formula (2), R ２ (This represents a saturated hydrocarbon group with 1 to 10 carbon atoms.)

4. A method for producing a propylene-based block copolymer according to claim 3, wherein the amount of gel formation inhibitor supplied is 10 to 150 parts by mass per 100 parts by mass of reaction inhibitor.

5. A method for producing a propylene-based block copolymer according to claim 1 or 2, wherein polymerization is carried out in the presence of a solid catalyst component containing magnesium, titanium, halogen, and an electron-donating compound as an internal donor, and an olefin polymerization catalyst containing an organoaluminum compound.

6. A method for producing a propylene-based block copolymer according to claim 1 or 2, comprising: producing a crystalline propylene-based polymer in a first step using one or more gas-phase fluidized bed polymerization reactors; and subsequently producing an amorphous propylene-α-olefin-based copolymer in the presence of the crystalline propylene-based polymer in a second step using one or more gas-phase polymerization reactors.

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