Method for producing solid titanium catalyst component and method for producing propylene-based block copolymer

Abstract

To provide a method for producing a propylene-based block copolymer that enables production of a molded article with superior appearance, and a method for producing a solid titanium catalyst component suitable for the same.SOLUTION: A method for producing a solid titanium catalyst component (A) comprises a step (Y) of bringing a magnesium-containing compound (a), a titanium-containing compound (b), and an optional electron donor (c) into contact with each other, the method further comprising a step (Z) of subjecting one or both of the magnesium-containing compound (a) particles and the solid titanium catalyst component particles having a specific particle shape to a specific airflow treatment.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a solid titanium catalyst component and a method for producing a propylene-based block copolymer. [Background technology]

[0002] Propylene-based resins are used in a variety of fields, including daily necessities, kitchen utensils, packaging films, home appliances, machine parts, electrical parts, and automobile parts.

[0003] Depending on the application, propylene-based block copolymers may be used, which are obtained by the so-called block copolymerization method, in which a propylene-based polymer is produced using an olefin polymerization catalyst, followed by the subsequent production of one or more of a rubber component, an amorphous or low-crystalline ethylene-propylene copolymer (EPR), and an amorphous ethylene-α-olefin copolymer. Propylene-based block copolymers exhibit excellent properties, including both heat resistance (e.g., a high melting point) and impact resistance. It is generally considered preferable for flexible copolymer components, such as the rubber component, to have a relatively high molecular weight. The purpose of these is to impart functionality such as impact resistance.

[0004] Furthermore, the olefin polymerization catalyst for producing the above-mentioned propylene-based block copolymer is often an olefin polymerization catalyst containing a so-called large particle size solid titanium catalyst component obtained by reacting a magnesium compound such as an alkoxymagnesium having a relatively large particle size with a titanium compound such as titanium tetrachloride.

[0005] It is obvious that the higher the content of the rubber component in a propylene-based block copolymer, the higher the impact resistance. However, the rubber component tends to bleed out, which can reduce particle flowability. Many production methods have been disclosed to solve this problem (for example, Patent Documents 1 to 4).

[0006] On the other hand, propylene-based block copolymers are also known to be used as raw materials for high-performance propylene polymer compounds used, for example, as main raw materials for various injection-molded articles and for automotive exterior and interior materials. In recent years, there has been a trend toward demands for high performance in a variety of physical properties for these propylene polymer compounds. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-132870 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-356507 [Patent Document 3] International Publication No. 2018 / 066535 [Patent Document 4] International Publication No. 2022 / 091867 Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, molded articles using propylene-based block copolymers or high-performance propylene polymer compounds are also required to have improved performance, such as appearance. On the other hand, since olefin copolymers such as the rubber component are usually incompatible with propylene polymers, it is said that there is a tendency for problems with appearance to occur.

[0009] As mentioned above, the impact resistance of the propylene-based block copolymer tends to depend on the molecular weight of the copolymer component (sometimes called the rubber component) contained therein, so it is often designed to contain a high molecular weight copolymer component. On the other hand, high molecular weight copolymer components tend to have low melt fluidity. For this reason, a lower content of the high molecular weight copolymer component in the block copolymer tends to be advantageous for moldability.

[0010] The propylene-based block copolymer obtained by the block copolymerization is often obtained in the form of particles. The content of the high-molecular-weight olefin copolymer component in the particles may vary from particle to particle. In particular, it is said that propylene block copolymer particles produced by a continuous polymerization method may have a wide variation in the content of the copolymer component due to factors such as residence time distribution. On the other hand, from the viewpoint of the appearance of the molded product, a low content of the copolymer in the particles tends to be preferable.

[0011] According to the investigations of the present inventors, when a propylene-based block copolymer obtained using a conventional catalyst is molded into an injection-molded or extrusion-molded product, foreign matter such as white dots may be found scattered on the surface of the product. Analysis of the foreign matter generally reveals that it is often a high-molecular-weight olefin copolymer.

[0012] From these facts, the present inventors speculated that the white spots occurring in the molded product were caused by the generation of polymer particles containing a high content of the olefin copolymer component of the propylene-based block copolymer, which made it difficult for the olefin copolymer component to be dispersed in the molded product.

[0013] Therefore, an object of the present invention is to provide a method for producing a propylene-based block copolymer that can produce a molded article with excellent appearance, and a method for producing a solid titanium catalyst component suitable for that method. [Means for solving the problem]

[0014] Further investigations by the present inventors have revealed that the olefin polymerization catalyst particles used in the production of propylene-based block copolymers that cause the above-mentioned appearance problems, and the magnesium-containing compound particles used in preparing the olefin polymerization catalyst particles, may contain small particles or particles with irregular shapes.

[0015] In view of the above-mentioned problems, the present inventors have conducted studies and have surprisingly found that a solid titanium catalyst component obtained by a method comprising the step of subjecting either or both of the magnesium-containing compound particles and particles containing a solid titanium catalyst component to a specific gas flow treatment to obtain magnesium-containing compound particles or a solid titanium catalyst component having a somewhat large average particle size can be used to produce a propylene-based block copolymer that easily gives a molded product with excellent appearance. That is, the present invention can be characterized by the following requirements.

[0016] [1] A method for producing a solid titanium catalyst component (A), comprising a step (Y) of contacting a magnesium-containing compound (a), a titanium-containing compound (b), and an optional electron donor (c), A method for producing a solid titanium catalyst component (A), further comprising a step (Z) of subjecting either or both of the particles containing the magnesium-containing compound (a) used in the step (Y) and the particles containing the solid titanium catalyst component obtained in the step (Y) to an airflow treatment that satisfies the following requirements (i) and (ii): (i) the average particle size (APS-1) (D50) is 30 to 60 μm; the minimum particle size (D0) is 30% or more and 70% or less of the average particle size (APS-1) (D50), the particles having protrusions on their surfaces with a value ranging from 1 to 15% of the average particle diameter (APS-1) (D50) are subjected to an air flow treatment; (ii) The average particle size (APS-2) (D50) of the particles after the airflow treatment (i) is 1.03 to 1.2 times the average particle size (APS-1).

[0017] [2] A step (P1) of producing polymer particles having a propylene-derived structural unit content of 90 mol% or more by polymerizing olefins including propylene in the presence of an olefin polymerization catalyst comprising the solid titanium catalyst component (A) obtained by the production method of [1] above, an organometallic compound (B), and an electron donor (C) as an optional component; and a step (P2) of copolymerizing propylene with an olefin other than propylene in the presence of the polymer particles produced in the step (P1); A method for producing a propylene-based block copolymer comprising the steps of: [Effects of the Invention]

[0018] According to the present invention, in the method for producing the block copolymer, a "step of obtaining slightly larger magnesium-containing compound particles or solid titanium catalyst component by subjecting either or both of the magnesium-containing compound particles and the particles containing a solid titanium catalyst component to a specific airflow treatment" is included. This makes it possible to stably produce a propylene-based block copolymer that is less likely to form white spots or the like during injection molding or extrusion molding and has an excellent appearance. [Brief explanation of the drawings]

[0019] [Figure 1] Figure 1 is a top view of the slit die. [Figure 2] FIG. 2 is a side view of the slit die. [Figure 3] FIG. 3 is a cross-sectional view taken along line AB of the slit die. [Figure 4] FIG. 4 is a front view of the cooling roll and air nozzle. [Figure 5] FIG. 5 is a side view of the cooling roll and the air nozzle. DETAILED DESCRIPTION OF THE INVENTION

[0020] The method for producing the solid titanium catalyst component (A) according to the present invention comprises the steps of: The method is characterized by comprising a step (Y) (hereinafter also referred to as "contact step (Y)") of contacting a magnesium-containing compound (a), a titanium-containing compound (b), and an electron donor (c), a representative example of which is preferably a phthalic acid diester, with each other, and further comprising a step (Z) (hereinafter also referred to as "airflow treatment step (Z)") of subjecting either or both of particles containing the magnesium-containing compound (a) and particles containing the solid titanium catalyst component to a specific airflow treatment.

[0021] The method for producing a propylene-based block copolymer according to the present invention comprises the steps of: (1) polymerizing olefins including propylene in the presence of an olefin polymerization catalyst containing the solid titanium catalyst component (A), an organometallic catalyst component (B), and an optional electron donor (C) to produce polymer particles having a propylene-derived structural unit content of 90 mol% or more; and (2) copolymerizing propylene with an olefin other than propylene in the presence of the polymer particles produced in the step (P1). This allows the production of a propylene-based block copolymer that can easily give molded articles with excellent appearance. Each requirement will be explained below in order.

[0022] [Method for producing solid titanium catalyst component (A)] The method for producing a solid titanium catalyst component (A) according to the present invention comprises a contacting step (Y) of contacting a magnesium-containing compound (a) such as an alkoxymagnesium compound with a titanium-containing compound (b) such as a liquid titanium compound and an electron donor (c) preferably such as a phthalic acid diester, and a gas stream treating step (Z) described below.

[0023] <Magnesium-containing compound (a)> The magnesium-containing compound (a) used in the present invention can be any known magnesium-containing compound (hereinafter, "magnesium-containing compound" may be referred to as "magnesium compound") used in the production of a solid titanium catalyst component, without any restrictions. For example, the magnesium compounds having an alkoxy group disclosed in Patent Documents 2 to 4 can be exemplified. Dialkoxymagnesium is preferred as such a magnesium compound having an alkoxy group. The magnesium-containing compound (a) can be used alone or in combination of two or more.

[0024] The dialkoxy magnesium may be at least one selected from diethoxy magnesium, dipropoxy magnesium, dibutoxy magnesium, dipentoxy magnesium, diisooctoxy magnesium, ethoxybutoxy magnesium, ethoxyisooctoxy magnesium, and the like, and diethoxy magnesium is preferred.

[0025] In addition to the above, examples include organic acid magnesium compounds such as magnesium stearate, and inorganic magnesium compounds such as magnesium oxide and magnesium halide salts.

[0026] Among these, alkoxy magnesium compounds are preferred, and particularly diethoxy magnesium compounds.

[0027] The magnesium-containing compound (a) preferably has a porous shape. When the magnesium-containing compound (a) has porosity, its pore size distribution can be measured by mercury intrusion porosimetry using a mercury intrusion porosimeter, for example.

[0028] The alkoxymagnesium compound can be obtained, for example, by contacting and reacting metallic magnesium with a corresponding alcohol and iodine under specific conditions, and alkoxymagnesium compounds having various pore shapes can be produced depending on the requirements of the conditions.

[0029] The secondary particles of the magnesium-containing compound (a) particles are in the form of granules or powder in a dry state, and are usually spherical in shape, but do not necessarily have to be perfectly spherical and may be ellipsoidal.

[0030] Specifically, the magnesium-containing compound (a) particles preferably have a ratio (l / w) of the major axis diameter l to the minor axis diameter w of the secondary particles of 3 or less, more preferably 1 to 2, and even more preferably 1 to 1.5.

[0031] The magnesium-containing compound (A) may contain an alcohol therein. For example, the magnesium-containing compound (A) preferably contains 0.1 to 1.5 parts by mass of alcohol, more preferably 0.2 to 1.2 parts by mass of alcohol, and even more preferably 0.4 to 1.0 part by mass of alcohol per 100 parts by mass of the magnesium-containing compound (a).

[0032] In the method for producing an olefin polymerization catalyst, the magnesium-containing compound (a) particles preferably have a bulk density of 0.1 to 0.6 g / ml, more preferably 0.2 to 0.5 g / ml, and even more preferably 0.25 to 0.40 g / ml.

[0033] The magnesium-containing compound (a) is a component that generally functions as a support for the solid titanium catalyst component, and is considered to have a significant effect on the shape of the solid titanium catalyst component (A) and the shape of the resulting propylene-based block copolymer.

[0034] The particles containing the magnesium-containing compound (a) as described above can be subjected to the airflow treatment described below. The magnesium-containing compound (a) particles before the airflow treatment are characterized by satisfying all of the following requirements. Details will be described later. The average particle size (APS-1) (median particle size D50) is 30 to 70 μm. The minimum particle size (D0) is 30% or more and 70% or less of the average particle size (APS-1) (D50). ·The surface has protrusions with a value ranging from 1 to 15% of the average particle diameter (APS-1) (D50). The above preferred ranges of values ​​will be described later.

[0035] <Titanium-containing compound (b)> The titanium-containing compound (b) used in the present invention is contacted with the magnesium-containing compound (a) to produce the solid titanium catalyst component (A). Any known liquid titanium compound that has been used to form a solid titanium catalyst component can be used as the titanium-containing compound (b) without any restrictions. More specifically, a preferred example of the titanium-containing compound (b) is a composition represented by the following formula (IV). The titanium-containing compound (b) may be used alone or in combination of two or more.

[0036] Ti(OR) g X 4-g (IV) In formula (IV), R is a hydrocarbon group, X is a halogen atom, and g is an integer that satisfies 0≦g≦4.

[0037] Examples of R in formula (IV) include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0038] Examples of titanium compounds represented by formula (IV) include titanium tetrahalides such as TiCl and TiBr; alkoxytitanium trihalides such as Ti(OCH)Cl, Ti(OCH)Cl, Ti(On-C4H)Cl, Ti(OCH)Br, and Ti(O-isoC4H)Br; alkoxytitanium dihalides such as Ti(OCH)Cl and Ti(OCH)Cl; alkoxytitanium monohalides such as Ti(OCH)Cl, Ti(On-C4H)Cl, and Ti(OCH)Br; and tetraalkoxytitanium tetrahalides such as Ti(OCH), Ti(OCH), Ti(OCH) and Ti(O-2-ethylhexyl). Of these, halogen-containing titanium compounds are preferred, titanium tetrahalides are more preferred, and titanium tetrachloride (TiCl) is even more preferred.

[0039] Among the above, it is believed that the halogen-containing titanium compound causes an exchange reaction between the alkoxy group of the alkoxymagnesium compound and the halogen, converting a part of the alkoxymagnesium compound into magnesium halide.

[0040] <Electron donor (c)> As the electron donor (c), any known electron donor disclosed for use in a solid titanium catalyst component can be used without limitation. Among them, phthalic acid diesters are preferred. R' in the ester group (-COOR') is preferably a hydrocarbon group having 3 to 20 carbon atoms. Multiple types of esters may be used in combination. The electron donor (c) may be used alone or in combination of two or more types.

[0041] Specific examples of the phthalic acid diester include di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, di-n-hexyl phthalate, diisohexyl phthalate, diheptyl phthalate, dioctyl phthalate, didecyl phthalate, didodecyl phthalate, ditetradecyl phthalate, dihexadecyl phthalate, dioctadecyl phthalate, dieicosyl phthalate, diphenyl phthalate, and dibenzyl phthalate.

[0042] Among the above-mentioned phthalic acid diesters, R' in the ester group (-COOR') is preferably a linear aliphatic hydrocarbon group, particularly a hydrocarbon group having 3 to 6 carbon atoms. The most preferred phthalic acid diester is di-n-butyl phthalate.

[0043] Examples of electron donors other than the phthalic acid diesters include aromatic carboxylic acid esters other than phthalic acid diesters, alicyclic carboxylic acid esters, and polyether compounds.

[0044] For example, alicyclic polycarboxylic acid esters and polyether compounds represented by the following formula (V) or (VI) are preferred.

[0045] R d (COOR e ) p ···(V) R d (OCOR e ) p (VI) In formula (V) and formula (VI), R d is an alicyclic hydrocarbon having 5 to 20 carbon atoms, and R e is a hydrocarbon group having 6 to 15 carbon atoms, and p is an integer of 2 or 3.

[0046] Examples of the alicyclic polycarboxylic acid ester represented by formula (V) include cyclohexyl-1,2-dihexanoate, cyclohexyl-1,2-dioctanoate, cyclohexyl-1,2-didecanoate, cyclohexyl-1,2-didodecanoate, cyclohexyl-1,2-diheptanoate, 3,6-dimethylcyclohexyl-1,2-dioctanate, 3,6-dimethylcyclohexyl-1,2-decenate, 3,6-dimethylcyclohexyl-1,2-dodecenate, 3-methyl-6-propylcyclohexyl-1,2-dioctanate, 3-methyl-6-propylcyclohexyl-1,2-didecenate, and 3-methyl-6-propylcyclohexyl-1,2-didodecenate.

[0047] Examples of the alicyclic polycarboxylic acid ester represented by formula (VI) include dioctyl 3,6-dimethylcyclohexane-1,2-dicarboxylate, didecyl 3,6-dimethylcyclohexane-1,2-dicarboxylate, dioctyl 3-methyl-6-ethylcyclohexane-1,2-dicarboxylate, didecyl 3-methyl-6-ethylcyclohexane-1,2-dicarboxylate, dioctyl 3-methyl-6-n-propylcyclohexane-1,2-dicarboxylate, didecyl 3-methyl-6-n-propylcyclohexane-1,2-dicarboxylate, and 3,6-diethylcyclohexane-1,2-dicarboxylate. and alicyclic polycarboxylic acid esters whose cyclic skeletons have no substituents other than carboxylic acid esters, such as di-n-hexyl cyclohexane-1,2-dicarboxylate, diheptyl cyclohexane-1,2-dicarboxylate, dioctyl cyclohexane-1,2-dicarboxylate, didecyl cyclohexane-1,2-dicarboxylate, and didodecyl cyclohexane-1,2-dicarboxylate.

[0048] The polyether compound is a compound having two or more ether bonds arranged on both sides via a plurality of carbon atoms. Examples of the polyether compound include 1,3-diethers such as 2-isopropyl-2-isobutyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, and 2,2-bis(cyclohexylmethyl)1,3-dimethoxypropane.

[0049] <Other ingredients> (Polar compounds with dipole moments between 0.50 and 4.00 Debye) In the method for producing a solid titanium catalyst component of the present invention, other compounds can also be used in combination. Among such compounds, preferred examples include polar compounds having a dipole moment of 0.50 to 4.00 Debye (hereinafter, sometimes simply referred to as "polar compounds"). As the polar compound, any known compound that has been used in the production of known solid titanium catalyst components can be used without limitation. The polar compounds can be used alone or in combination of two or more.

[0050] Specific examples of the polar compounds include halogen-containing aromatic hydrocarbons such as chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, trichlorobenzene, α,α,α-trichlorotoluene, o-chlorotoluene, 2,4-dichlorotoluene, benzyl chloride, and 2-chlorobenzyl chloride; halogen-containing aliphatic hydrocarbons such as 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chloropropane, 2-chloropropane, 1,2-dichloropropane, 1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane, 2-chloro-2-methylpropane, and 1-chloropentane; and halogen-containing silicon compounds such as diphenyldichlorosilane and methyltrichlorosilane. Among these, halogen-containing aromatic hydrocarbons are preferred. More preferred examples include o-dichlorobenzene and 2,4-dichlorotoluene.

[0051] In addition to these, examples of compounds having a dipole moment outside the above range include aromatic hydrocarbon compounds such as toluene and xylene.

[0052] In the present invention, the specific solid titanium catalyst component (A) produced using the polar compound tends to reduce the by-production of components with a high content of ethylene-derived structural units, as described below. The inventors believe that this performance is due to the fact that the polar compound strongly interacts with active species, particularly those with a strong electron-deficiency, i.e., high acidity, among the multiple titanium-based polymerization active species that may exist, thereby abstracting the titanium that forms the active species, or interacting with the alkoxymagnesium-based support surface where the exchange reaction with halogen proceeds excessively, resulting in increased ethylene polymerization activity, thereby reducing the polymerization reaction activity, thereby removing, deactivating, or suppressing active species that may be particularly susceptible to ethylene reaction. It is also speculated that the relatively electron-deficient alkoxymagnesium-based support surface may be the site where the halogen becomes relatively excessive due to the halogen exchange reaction with the halogen-containing titanium compound.

[0053] <Contact process (Y)> Preferred examples of the contact step (Y) in producing the solid titanium catalyst component (A) are given below.

[0054] The alkoxymagnesium compound and phthalate diester are suspended in an aromatic hydrocarbon medium, such as toluene, under an inert gas atmosphere. A liquid titanium compound is then added at a relatively low temperature, such as 0°C to room temperature, and the mixture is heated to approximately 100°C to react. The liquid phase is then removed by decantation or other methods, and the liquid titanium compound is re-added and resuspended for further reaction. This liquid phase removal and reaction with the liquid titanium compound can be repeated multiple times. A polar compound with a dipole moment of 0.50 to 4.00 Debye can be used in one or more of these steps. This "removal and resuspension step" is preferably carried out at a temperature between 80°C and 120°C, for example, to remove excess titanium compound and electron donors, such as phthalate diester, and to form stable polymerization active species. Furthermore, this "removal and resuspension step" can also be carried out using an aromatic hydrocarbon medium, such as toluene, or by washing with an aromatic hydrocarbon medium, such as toluene, after removal of the liquid phase.

[0055] The contact of the above-mentioned components is usually carried out at a temperature of −70° C. to +200° C., preferably −50° C. to +150° C., and more preferably −30° C. to +130° C. The amounts of the components used in preparing the solid titanium catalyst component (A) vary depending on the preparation method and cannot be generally defined. However, for example, the electron donor (c) can be used in an amount of 0.01 to 10 mol, preferably 0.1 to 5 mol, and the titanium-containing compound (b) can be used in an amount of 0.01 to 1000 mol, preferably 0.1 to 200 mol, per 1 mol of the magnesium-containing compound (a).

[0056] When the polar compound is used, it is usually used in an amount of 1 to 10,000 ml, preferably 5 to 5,000 ml, more preferably 10 to 1,000 ml per gram of the solid titanium catalyst component (A).

[0057] When a liquid titanium compound is used in combination with a polar compound, the polar compound is usually used in an amount of 0.1 to 50 ml, preferably 0.2 to 20 ml, and particularly preferably 0.3 to 10 ml per 100 ml of the liquid titanium compound.

[0058] The phthalic acid diester is used in an amount of usually 0.01 to 10 ml, preferably 0.02 to 5 ml, and particularly preferably 0.03 to 3 ml, per 100 ml of the polar compound.

[0059] The above method can also be carried out by other known methods such as the following (P-1) to (P-6). (P-1) A slurry of an alkoxymagnesium compound in an inert hydrocarbon solvent is contacted with a liquid titanium compound and a phthalic acid diester, and then the resulting mixture is contacted with the polar compound. (P-2) A slurry of an alkoxy magnesium compound is contacted with a liquid titanium compound and preferably one or more of the above-mentioned phthalic acid diesters in multiple batches, and the polar compound is introduced at any stage. (P-3) A slurry of an alkoxy magnesium compound is brought into contact with a liquid titanium compound, and the reaction is allowed to proceed. After that, a phthalic acid diester is introduced, and the liquid titanium compound is brought into contact with the polar compound in multiple batches. (P-4) A slurry of an alkoxy magnesium compound is brought into contact with a liquid titanium compound to allow the reaction to proceed, and then a phthalic acid diester is introduced. The liquid titanium compound, an electron donor such as a phthalic acid diester, and the polar compound are brought into contact with each other in multiple batches. (P-5) A slurry of an alkoxy magnesium compound is brought into contact with a liquid titanium compound, and the reaction is allowed to proceed. After that, a phthalic acid diester is introduced, and the liquid titanium compound is brought into contact with an aromatic hydrocarbon liquid in multiple batches. (P-6) A slurry of an alkoxy magnesium compound is brought into contact with a liquid titanium compound to allow the reaction to proceed, after which a phthalic acid diester is introduced, and the liquid titanium compound, an electron donor such as a phthalic acid diester, and an aromatic hydrocarbon liquid are brought into contact with each other in multiple batches.

[0060] In the above (P-4) and (P-6), a phthalate diester or other electron donor is used multiple times, and in such cases, a method including a step of using a different compound at least once may be preferable. This method is expected to exhibit the following effects. Generally, solid titanium catalyst components contain a variety of active species. When a single electron donor cannot form sufficiently high-performance active sites, the use of two or more electron donors may allow the formation of a larger number of high-performance active sites. In particular, when using different electron donors, it may be preferable to use different electron donors in different types of processes.

[0061] The magnesium content of this solid titanium catalyst component (A) is preferably 10 to 35 mass%, more preferably 12 mass%, even more preferably 14 mass%, and particularly preferably 15 mass%, while the upper limit is more preferably 33 mass%, even more preferably 31 mass%, and particularly preferably 30 mass%.

[0062] The titanium content is preferably 2.5 mass % or less, more preferably 0.1 to 2.2 mass %, even more preferably 0.2 to 2.0 mass %, particularly preferably 0.3 to 1.8 mass %, and most preferably 0.4 to 1.4 mass %.

[0063] The content of the electron donor is preferably 8 to 30% by mass. The electron donor / titanium (mass ratio) is preferably 7 or more, more preferably 7.5 to 35, even more preferably 8 to 30, and particularly preferably 8.5 to 25.

[0064] In most cases, the above polar compounds are hardly detected in the solid titanium catalyst component (A).

[0065] The solid titanium catalyst component thus obtained can be subjected to the airflow treatment described below to produce the solid titanium catalyst component (A). The particles before the airflow treatment are characterized by satisfying all of the following requirements, which will be described in detail later. The average particle size (APS-1) (D50) is 30 to 70 μm. The minimum particle size (D0) is 30% or more and 70% or less of the average particle size (APS-1) (D50). ·The surface has protrusions with a value ranging from 1 to 15% of the average particle diameter (APS-1) (D50). The above preferred ranges of values ​​will be described later.

[0066] <Airflow treatment process (Z)> The method for producing a solid titanium catalyst component (A) of the present invention is characterized by including, in addition to the contacting step (Y), an airflow treatment step (Z) for treating a solid component (specific particles) with an airflow. Preferably, the method includes a step of airflow treatment of particles containing the magnesium-containing compound (a) (hereinafter also referred to as "step (Z-1)") and a step of airflow treatment of particles containing the solid titanium catalyst component obtained by the method (hereinafter also referred to as "step (Z-2)"). Either step (Z-1) or step (Z-2) may be performed, or both steps (Z-1) and (Z-2) may be performed. Among the above, the method including step (Z-1) for airflow treatment of the magnesium-containing compound (a) is preferred.

[0067] In the present invention, the target solid titanium catalyst component (A) can be obtained by combining the contact step (Y) and the gas stream treatment step (Z).

[0068] In such gas flow treatment, the amount of inert gas supplied per gram of particles containing the magnesium-containing compound (a) or the solid titanium catalyst component is preferably 1 to 500 liters. The lower limit is more preferably 5 liters, even more preferably 8 liters, and particularly preferably 10 liters. On the other hand, the upper limit is more preferably 400 liters, even more preferably 300 liters, and particularly preferably 250 liters.

[0069] The gas supply time in the above-mentioned gas flow treatment is not particularly limited, but a preferred range is 1 second to 5 hours. A more preferred lower limit is 5 seconds, even more preferably 10 seconds, and particularly preferably 20 seconds. On the other hand, a more preferred upper limit is 4 hours, even more preferably 2 hours, and particularly preferably 2.5 hours. The gas flow treatment may be performed as a batch treatment, a continuous treatment, or a semi-continuous treatment, but a continuous treatment is preferred. In the case of a continuous treatment, the above-mentioned time can be considered to correspond to the residence time.

[0070] The particle density per unit volume during the gas flow treatment is preferably 0.001 to 0.3 kg / L. A more preferred lower limit is 0.003 kg / L, even more preferably 0.005 kg / L, and particularly preferably 0.007 kg / L. On the other hand, a more preferred upper limit is 0.2 kg / L, even more preferably 0.15 kg / L, and particularly preferably 0.1 kg / L. The above ranges are based on the batch method, but in the case of a continuous method, they can be considered as the supply rate per unit volume of the particles. Such a rate is preferably 0.001 to 0.3 kg / (liter min). A more preferred lower limit is 0.003 kg / (liter min), even more preferably 0.005 kg / (liter min), and particularly preferably 0.007 kg / (liter min). On the other hand, a more preferable upper limit is 0.2 kg / (liter·min), even more preferably 0.15 kg / (liter·min), and particularly preferably 0.1 kg / (liter·min).

[0071] The above-mentioned airflow treatment can also be carried out by forcibly moving particles containing the magnesium-containing compound (a) and the solid titanium catalyst component. In such a case, the preferred speed is 10 to 5,000 m / min. The more preferred lower limit is 50 m / min, even more preferably 80 m / min, and particularly preferably 100 m / min. On the other hand, the more preferred upper limit is 4,000 m / min, even more preferably 3,000 m / min, and particularly preferably 2,500 m / min.

[0072] Examples of methods for moving such particles include stirring with a rotary blade and supplying an inert gas while rotating the gas supply device itself.

[0073] The flow rate of the supply gas per unit area in the above-mentioned gas flow treatment is preferably 5 to 1000 liters / (min cm 2 ) is preferable. A more preferable lower limit is 10 liters / (min cm 2 ), and more preferably 15 liters / (min cm 2 ), and 20 liters / (min cm) is particularly preferred. 2 On the other hand, a more preferable upper limit is 800 liters / (min cm 2 ), and more preferably 600 liters / (min cm 2 ), and particularly preferably 500 liters / (min cm 2 )

[0074] The inert gas may be supplied from one direction or from multiple directions using multiple supply ports. Alternatively, the gas may be supplied while rotating the gas supply device, as described above. Two or more of the above methods may be used in combination. These methods, as well as known methods that utilize the shape of the device, can be used to control the generation of turbulence, vortexes, etc., and improve the efficiency of airflow treatment.

[0075] When the airflow treatment is performed under the above-mentioned preferable conditions, the small particles tend to be easily blown away by the fast airflow and thus easily separated from the large particles, and therefore it is possible to obtain large particles from which the fine particles originally contained in the particles containing the magnesium-containing compound (a) or the solid titanium catalyst component, as well as the "fine particles derived from the surface protrusions" described below, have been removed.

[0076] Under conditions exceeding the upper limit, collisions between particles occur too frequently, resulting in deformation or destruction of the particles, and in some cases the particles may be blown away, making it impossible to recover some of them. On the other hand, if the flow rate is lower than the above-mentioned range, it tends to be difficult to obtain the effects of the present invention described below.

[0077] The inert gas may be any known inert gas, including hydrocarbon gases such as nitrogen, methane, ethane, propane, etc., and rare gases such as helium, neon, argon, etc. Among these, nitrogen gas is preferred from the viewpoints of cost, effectiveness, availability, etc.

[0078] The airflow treatment step (Z) is characterized by satisfying the following requirements (i) and (ii): As described above, the particles used in the airflow treatment include the magnesium-containing compound (a) and a solid titanium catalyst component in the process of being produced.

[0079] (i) the average particle size (APS-1) (corresponding to D50 of the median particle distribution) is 30 to 70 μm; the minimum particle size (APS-0) (corresponding to D0 in the median particle size distribution) is 30% or more and 70% or less of the average particle size (APS-1), The particles having protrusions on their surfaces with a value ranging from 1 to 15% of the average particle diameter (APS-1) are subjected to an air flow treatment. (ii) The average particle size (APS-2) after the airflow treatment (i) (corresponding to D50 of the median particle distribution) is 1.03 to 1.2 times the average particle size (APS-1).

[0080] The lower limit of the APS-1 is preferably 35 μm, more preferably 38 μm, and even more preferably 40 μm, while the upper limit is preferably 65 μm, more preferably 62 μm, and even more preferably 60 μm.

[0081] The lower limit of the ratio of APS-0 to (APS-1) is preferably 35%, more preferably 38%, and even more preferably 40%, while the upper limit is preferably 65%, more preferably 62%, and even more preferably 60%.

[0082] The lower limit of the width of the protrusions on the particle surface is preferably 2%, more preferably 3%, and even more preferably 4% of (ASP-1), while the upper limit is preferably 14%, more preferably 13%.

[0083] By carrying out the airflow treatment of the present invention, the particles subjected to the airflow treatment tend to become slightly larger than those before the treatment. The lower limit of the particle size ratio is preferably 1.04 times, more preferably 1.05 times. Meanwhile, the upper limit is preferably 1.17 times, more preferably 1.15 times.

[0084] The particle size and particle size distribution can be determined by a method using a laser diffraction / scattering particle size distribution analyzer manufactured by Beckman Coulter.

[0085] Within the above range, the solid titanium catalyst component (A) obtained by the method of the present invention is likely to be a solid titanium catalyst component advantageous for producing a propylene-based block copolymer suitable for producing a melt-molded product having excellent appearance, as will be described later.

[0086] The method for producing a solid titanium catalyst component (A) of the present invention is characterized by including the above-mentioned gas stream treatment step (Z). Surprisingly, by including this step, when a propylene-based block copolymer produced using the solid titanium catalyst component is subjected to injection molding or extrusion molding, foreign matter such as white spots is unlikely to be observed, and molded articles with excellent appearance tend to be obtained. The reason for this effect is not clear at present, but the present inventors believe that it includes the following factors.

[0087] As described above, in the method for obtaining a solid titanium catalyst component by contacting a magnesium-containing compound (a), a titanium-containing compound (b), and an optional electron donor (c), the solid titanium catalyst component particles may have irregular shapes, such as protrusions on the surface. Furthermore, when a propylene-based block copolymer obtained using a solid titanium catalyst component containing particles of such shapes (especially obtained by a continuous polymerization method) is used, the molded product tends to have white spots.

[0088] The following are thought to be the factors that explain this trend: The protrusions and irregularly shaped particles described above may fall off during the process of preparing the solid titanium catalyst component or during the propylene polymerization process (the process of producing a crystalline propylene polymer) described below, resulting in the generation of fine powder, or the particles may break down and become smaller in diameter. Finely divided or small-sized catalyst particles and propylene polymer particles tend to short-pass the propylene polymerization process and may be easily charged with static electricity during the process. The particles that have been short-passed are likely to remain for a long time in the olefin copolymerization stage, which corresponds to the latter stage of propylene-based block copolymerization, due to factors such as small diameter and electrostatic charge. Therefore, the polymer particles obtained from such catalyst particles will have a relatively large copolymer component, and will become propylene-based block copolymer particles with a large olefin copolymer portion, which is generally a high molecular weight substance. When such a propylene-based block copolymer is used in melt molding, the high molecular weight olefin copolymer portion is less likely to disperse than other particle portions, and is more likely to form white spots.

[0089] The most fundamental method for solving the above problems is to reduce the number of particles with protrusions on the surface and distorted particles.

[0090] The airflow treatment of the present invention is - Collisions between particles caused by the airflow remove surface protrusions; The shaved particles (from surface protrusions) are easily blown away and removed by the airflow; - Collisions between particles caused by the airflow destroy distorted particles (which are considered to be inherently unstable); The broken particles are also removed by the airflow; It is possible that the catalyst particles that cause the white spots are removed due to factors such as the above. Therefore, the propylene-based block copolymer obtained by using the solid titanium catalyst component obtained by the method of the present invention may be used to obtain a molded product with excellent appearance by melt molding or the like.

[0091] Furthermore, the use of the method for producing a solid titanium catalyst component including the gas stream treatment step (Z) of the present invention will also lead to a reduction in fouling and the like, regardless of whether the method is a batch polymerization method or a continuous polymerization method.

[0092] [Method for producing propylene-based block copolymer] The propylene-based block copolymer can be produced through a first polymerization step in which propylene and optionally other α-olefins are polymerized in the presence of an olefin polymerization catalyst containing the solid titanium catalyst component (A) and the organometallic catalyst component (B) to produce a crystalline propylene-based (co)polymer, and a second polymerization step in which ethylene, propylene, and, if necessary, a component containing a polymerizable double bond, such as an olefin having 4 to 20 carbon atoms or a diene, are copolymerized in the presence of the crystalline propylene-based (co)polymer produced in the first polymerization step to produce an olefin rubber component, an amorphous or low-crystalline ethylene-propylene copolymer (EPR), and an amorphous ethylene-α-olefin copolymer.

[0093] in particular, the solid titanium catalyst component (A); an organometallic compound (B); Optionally, an electron donor (C) a step (P1) of polymerizing an olefin including propylene in the presence of an olefin polymerization catalyst containing the above to produce polymer particles having a content of propylene-derived structural units of 90 mol % or more; a step (P2) of copolymerizing propylene with an olefin other than propylene in the presence of the polymer particles produced in the step (P1); The present invention is characterized by comprising:

[0094] The lower limit of the content of structural units derived from propylene in the polymer particles produced in the first step (P1) is preferably 93 mol%, more preferably 95 mol%, and even more preferably 97 mol%, and the upper limit is, of course, 100 mol%.

[0095] The solid titanium catalyst component (A) may be used alone or in combination of two or more kinds, and the organometallic catalyst component (B) may be used alone or in combination of two or more kinds.

[0096] The first polymerization step (P1) and the second polymerization step (P2) may be carried out by any of liquid phase polymerization methods including bulk polymerization, solution polymerization, and suspension polymerization, as well as gas phase polymerization. Also, either a batch polymerization method or a continuous polymerization method can be employed. Preferably, a polymerization method including gas phase polymerization is used, and more preferably, a continuous polymerization method is used.

[0097] The organometallic catalyst component (B) may be an organometallic compound containing at least one element selected from the group consisting of Group 1 elements, Group 2 elements, and Group 13 elements of the periodic table.

[0098] Examples of the organometallic catalyst component (B) include compounds containing a Group 13 element such as organoaluminum compounds, alkylated complexes of Group 1 elements with aluminum, and organometallic compounds containing Group 2 elements.

[0099] Preferred are organoaluminum compounds, specifically trialkylaluminum compounds such as triethylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, and trioctylaluminum, with triethylaluminum being particularly preferred.

[0100] The olefin polymerization catalyst can also be used in combination with an electron donor (C). Examples of the electron donor (C) include organosilicon compounds represented by formula (VII), silane compounds represented by formula (VIII), and compounds represented by formula (IX). The electron donor (C) can be used alone or in combination of two or more.

[0101] R n Si(OR') 4-n (VII) Si(ORa )3(NR b R c ) ···(VIII) RNSi(OR a )3···(IX)

[0102] In formula (VII), R and R’ are hydrocarbon groups, and n is an integer where 0 < n < 4. In formula (VIII), R a is a hydrocarbon group having 1 to 6 carbon atoms, R b is a hydrocarbon group having 1 to 12 carbon atoms or hydrogen, and R c is a hydrocarbon group having 1 to 12 carbon atoms.

[0103] In formula (IX), R a is a hydrocarbon group having 1 to 6 carbon atoms, and RN is a cyclic amino group such as a perhydroquinolino group, a perhydroisoquinolino group, a 1,2,3,4-tetrahydroquinolino group, a 1,2,3,4-tetrahydroisoquinolino group, and an octamethyleneimino group.

[0104] Examples of the organosilicon compound represented by formula (VII) include diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, t-amylmethyldiethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, phenyltriethoxysilane, cyclohexyltrimethoxysilane, cyclopentyltrimethoxysilane, 2-methylcyclopentyltrimethoxysilane, cyclopentyltriethoxysilane, dicyclopentyldimethoxysilane, dicyclopentyldiethoxysilane, tricyclopentylmethoxysilane, dicyclopentylmethylmethoxysilane, dicyclopentylethylmethoxysilane, cyclopentyldimethylethoxysilane, and the like.

[0105] Examples of the silane compound represented by formula (VIII) include dimethylaminotriethoxysilane, diethylaminotrimethoxysilane, diethylaminotri-n-propoxysilane, di-n-propylaminotriethoxysilane, methyl-n-propylaminotriethoxysilane, t-butylaminotriethoxysilane, ethyl-n-propylaminotriethoxysilane, ethyl-iso-propylaminotriethoxysilane, and methylethylaminotriethoxysilane.

[0106] Examples of the compound represented by formula (IX) include (perhydroquinolino)triethoxysilane, (perhydroisoquinolino)triethoxysilane, (1,2,3,4-tetrahydroquinolino)triethoxysilane, (1,2,3,4-tetrahydroisoquinolino)triethoxysilane, and octamethyleneiminotriethoxysilane.

[0107] The temperature at which component (A) and component (B) are contacted to form the olefin polymerization catalyst is preferably −30° C. or higher and 150° C. or lower, more preferably −25° C. or higher and 130° C. or lower, and even more preferably −25° C. or higher and 120° C. or lower.

[0108] The amount of the solid titanium catalyst component (A) used in the first polymerization step and the second polymerization step can be 0.0001 mmol or more and 0.5 mmol or less, and preferably 0.005 mmol or more and 0.1 mmol or less, in terms of titanium atom per liter of polymerization volume.

[0109] The amount of the organometallic catalyst component (B) used in the first and second polymerization steps can be 1 mole or more and 2000 moles or less, and preferably 5 moles or more and 500 moles or less, per mole of titanium atom in the polymerization system.

[0110] The amount of the electron donor (C) used as needed in the first polymerization step and the second polymerization step can be 0.001 mol or more and 50 mol or less, preferably 0.01 mol or more and 30 mol or less, and more preferably 0.05 mol or more and 20 mol or less, per 1 mol of the organometallic catalyst component (B) in the polymerization system.

[0111] The polymerization temperature in the first polymerization step and the second polymerization step can be 20°C or higher and 200°C or lower, preferably 30°C or higher and 100°C or lower, and more preferably 50°C or higher and 90°C or lower.

[0112] The pressure (gauge pressure) in the first polymerization step and the second polymerization step can be set to normal pressure to 9.8 MPa or less, and is preferably 0.20 MPa or more and 4.9 MPa or less.

[0113] In the first and second polymerization steps, polymerization may be carried out in the presence of hydrogen in order to reduce the molecular weight of the resulting polymer and adjust the melt flow rate (MFR) and the intrinsic viscosity [η] of the Dsol component described below to within desired ranges.

[0114] In the second polymerization step, for example, propylene, which is the raw material for the rubber component, and one or more α-olefins selected from ethylene and α-olefins having 4 to 20 carbon atoms may be polymerized with the crystalline propylene (co)polymer obtained in the first polymerization step. For example, when the rubber component is a propylene-ethylene copolymer rubber, the ethylene / (ethylene+propylene) gas ratio is preferably 5 mol% to 80 mol%, more preferably 10 mol% to 70 mol%, and even more preferably 15 mol% to 60 mol%.

[0115] Note that, prior to the first polymerization step and the second polymerization step, prepolymerization may be carried out at a higher catalyst concentration. The prepolymerization is preferably carried out at a temperature lower than the polymerization temperature, specifically, for example, in the range of 0 to 50°C.

[0116] [Propylene block copolymer] The propylene-based block copolymer can be obtained, for example, by polymerizing an olefin containing ethylene and propylene in the presence of a crystalline propylene-based polymer to produce a rubber component, an amorphous or low-crystalline ethylene-propylene copolymer (EPR), an amorphous ethylene-α-olefin copolymer, or the like.

[0117] The propylene-based block copolymer is usually in the form of powder or pellets, and more preferably in the form of propylene-based block copolymer particles formed during polymerization, which will be described later.

[0118] The propylene-based block copolymer is not particularly limited as long as it is a block copolymer containing structural units derived from propylene. However, from the viewpoints of having a good balance of rigidity, impact resistance, and moldability and being able to easily obtain molded articles with good appearance, it is preferable that the propylene-based block copolymer is a copolymer containing a rubber component, and more preferable that the propylene-based block copolymer is a copolymer having a component soluble in n-decane at 23°C (hereinafter also referred to as the "Dsol component") and a component sparingly soluble in n-decane at 23°C (hereinafter also referred to as the "Dinsol component").

[0119] The Dsol component refers to the component that is dissolved in the n-decane solution after the propylene-based block copolymer is heated and dissolved in n-decane at 150°C for 2 hours and then cooled to 23°C. The other components in the propylene-based block copolymer are Dinsol components.

[0120] The Dsol component may be a component in which the rubber component is the main component, and is preferably a component in which the main component is a copolymer rubber component of propylene and one or more α-olefins selected from ethylene and α-olefins having a carbon number of 4 to 20. More specifically, the proportion of the rubber component in the Dsol component is preferably more than 50% by mass, and 80% to 100% by mass, and more preferably 90% to 100% by mass.

[0121] Examples of the α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. The α-olefin to be copolymerized is preferably an α-olefin selected from ethylene or an α-olefin having 4 to 10 carbon atoms, and more preferably an α-olefin selected from ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene.

[0122] The content of structural units derived from one or more α-olefins selected from ethylene and α-olefins having 4 to 20 carbon atoms contained in the Dsol component is higher than the content of structural units derived from ethylene or α-olefins having 4 to 20 carbon atoms contained in the crystalline propylene-based (co)polymer component described below or the decane-insoluble component (Dinsol component), and is usually 25 mol % or more of the copolymer rubber.

[0123] In particular, since a Dsol component containing ethylene units tends to have a low glass transition temperature, it is preferable that the Dsol component contains a large amount of ethylene units.

[0124] The lower limit of the ethylene unit content in the Dsol component is preferably 30 mol%, more preferably 36.0 mol%, and even more preferably 40 mol%, while the upper limit is preferably 70 mol%, more preferably 65 mol%, and even more preferably 60 mol%.

[0125] When the content of ethylene units becomes relatively high, the glass transition temperature of the rubber component decreases and the crystallinity also decreases, so the rubber component becomes flexible and has excellent impact resistance.

[0126] From the viewpoint of easily obtaining a molded article having a well-balanced excellent rigidity and impact resistance, the content of the Dsol component in the propylene-based block copolymer is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 50% by mass or less, even more preferably 25% by mass or more and 50% by mass or less, and particularly preferably 30% by mass or more and 40% by mass or less, relative to 100% by mass of the total of the Dsol component and the Dinsol component.

[0127] The intrinsic viscosity [η] of the Dsol component is preferably 1.5 dL / g or more and 10.0 dL / g or less, and more preferably 2.0 dL / g or more and 7.0 dL / g or less, from the viewpoints that a composition having a good balance of impact resistance, high fluidity, and high melt elasticity can be easily obtained, and that a molded article having a good appearance can be easily obtained.

[0128] The above [η] can be the value of ηsp / C when the concentration (C) is extrapolated to 0 in the equation showing the relationship between concentration and specific viscosity, obtained by dissolving 20 mg of propylene-based block copolymer in 15 ml of decalin, measuring the specific viscosity ηsp in an oil bath at 135°C, diluting the decalin solution by adding 5 ml of decalin solvent, and then measuring the specific viscosity ηsp three more times.

[0129] The Dinsol component is a component mainly composed of a crystalline propylene-based (co)polymer component. More specifically, the content of the crystalline propylene-based (co)polymer component in the Dinsol component is more than 50% by mass, preferably 80% to 100% by mass, and more preferably 90% to 100% by mass.

[0130] The crystalline propylene (co)polymer component is a crystalline propylene homopolymer or a copolymer of propylene and one or more α-olefins selected from ethylene and α-olefins having a carbon number of 4 to 20. The proportion of structural units derived from the α-olefin is preferably 1.5 mol % or less, where the total structural units derived from all olefins in the crystalline propylene (co)polymer component is 100 mol %.

[0131] The content of the Dinsol component in the propylene-based block copolymer is preferably 50% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, even more preferably 50% by mass or more and 75% by mass or less, and particularly preferably 60% by mass or more and 70% by mass or less, relative to 100% by mass of the total of the Dsol component and the Dinsol component, from the viewpoint of easily obtaining a molded product having an excellent balance of rigidity and impact resistance.

[0132] Examples of the α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. The α-olefin to be copolymerized is preferably an α-olefin selected from ethylene or an α-olefin having 4 to 10 carbon atoms, and more preferably an α-olefin selected from ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene.

[0133] The melt flow rate (MFR) of the propylene-based block copolymer, measured at 230°C under a load of 2.16 kg according to a method in accordance with ASTM D1238, can be 5 g / 10 min or more and 300 g / 10 min or less, and preferably 5 g / 10 min or more and 200 g / 10 min or less.

[0134] Propylene-based block copolymers having an MFR in the above range have excellent fluidity, and therefore can be used to obtain compositions that can be easily injection-molded. Furthermore, these compositions can be easily used to obtain molded articles that have excellent impact resistance and are suitable for use in automobile parts, etc.

[0135] The content of the propylene-based block copolymer relative to the total mass of the composition is preferably 58% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 90% by mass or less, from the viewpoint that a molded product having an excellent balance between rigidity and impact resistance can be easily obtained.

[0136] The composition may contain other components such as a resin other than the propylene-based block copolymer, a light stabilizer, a heat stabilizer, a weathering stabilizer, an antioxidant, an antioxidant, a fatty acid metal salt, a softener, a dispersant, a filler, a colorant, a pigment, an antistatic agent, a slip agent, an antiblocking agent, an antifogging agent, a lubricant, a natural oil, a synthetic oil, or a wax.

[0137] The composition can also be used as a compound with a resin other than the propylene-based block copolymer or a rubber component. Suitable polymers for use as the rubber component include known elastomers such as ethylene / propylene copolymer, ethylene / butene copolymer, ethylene / octene copolymer, ethylene / propylene / diene terpolymer, ethylene / butene / diene terpolymer, styrene-based thermoplastic elastomer, butadiene rubber, isoprene rubber, and butyl rubber.

[0138] Examples of the additives such as stabilizers include hindered amines, hindered phenols, and phosphorus-based stabilizers, and examples of the fillers include glass fiber, carbon fiber, talc, and mica.

[0139] The propylene-based block copolymer obtained by the production method according to the present invention can be molded into various molded articles by known molding methods, such as injection molding, (T-die) extrusion molding, inflation molding, blow molding, vacuum molding, stamping molding, rotational molding, and roll molding.

[0140] Suitable examples of such molded articles include exterior materials (bumpers, back doors, etc.) and interior materials (instrument panel materials, etc.) for automobiles, which can take advantage of the high rigidity, heat resistance, and impact resistance of the molded articles. [Example]

[0141] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the descriptions in the examples.

[0142] The various analytical methods are as follows: (1) Melt flow rate (MFR) The melt flow rate (MFR) was measured in accordance with ASTM D1238E standard at a measurement temperature of 230°C and a load of 2.16 kg. (2) Bulk density (BD) The bulk density (BD) was measured according to the JIS K-6721 standard.

[0143] (3) Decane soluble content (Dsol), ethylene unit content In a glass measuring vessel, add approximately 3 grams (10 -4The mass was measured to the nearest gram. This mass was represented as b (grams) in the formula below. ), 500 ml of decane, and a small amount of a heat stabilizer that was soluble in decane and had a boiling point that was substantially distilled off during vacuum drying, as described below, were added. The mixture was heated to 150°C over 2 hours while stirring with a stirrer under a nitrogen atmosphere to dissolve the propylene polymer, and then maintained at 150°C for 2 hours, followed by gradual cooling to 23°C over 8 hours. The resulting liquid containing a precipitate of the propylene polymer was filtered under reduced pressure using a 25G-4 glass filter manufactured by Tokyo Glass Instruments Co., Ltd. 100 ml of the filtrate was collected and dried under reduced pressure to obtain a portion of the decane-soluble component, and the mass of this was reduced to 10 -4 The mass was measured to the unit of grams (this mass is represented as a (grams) in the formula below). After this operation, the content of the decane-soluble component was determined by the formula below. Decane soluble component content = 100×(500×a) / (100×b)

[0144] The content of ethylene-derived units was measured using the decane-soluble component obtained by the above-mentioned vacuum drying at 125 MHz. 13 Measurement was performed using C NMR (Bruker Biospin, AVANCE IIIcryo-500 instrument), and the ethylene-derived units and propylene-derived units were identified by the usual method, and the units were identified from their absorption intensity ratio.

[0145] (4) Intrinsic viscosity ([η]: [dl / g]) Measurement was performed at 135 ° C using decalin solvent. Approximately 20 mg of sample was dissolved in 15 ml of decalin, and the specific viscosity ηsp was measured in an oil bath at 135 ° C. 5 ml of decalin solvent was added to this decalin solution to dilute it, and the specific viscosity ηsp was measured in the same manner. This dilution procedure was repeated two more times, and the value of ηsp / C when the concentration (C) was extrapolated to 0 was determined as the limiting viscosity.

[0146] (5) Measurement of particle size and particle size distribution of catalyst-related particles Measurements were carried out in the usual manner using a Beckman Coulter laser diffraction / scattering particle size distribution analyzer.

[0147] (6) Surface shape of catalyst particles Photographs of the catalyst particle surface were taken at 1000x magnification using a Hitachi High-Tech TM4000plus electron microscope, and if there were protrusions on the surface, the width of any (5) or more protrusions on the particles was measured and the average value was calculated.

[0148] (7) Film evaluation (7-1) Pellets preparation method 100 parts by mass of the propylene-based block copolymer obtained in the Examples and Comparative Examples described below were mixed with 0.1 parts by mass of antioxidant IRGANOX 1010 (BASF Japan Ltd.), 0.1 parts by mass of heat stabilizer IRGAFOS 168 (BASF Japan Ltd.), and 0.1 parts by mass of neutralizer calcium stearate, and then melt-kneaded in a small single-screw extruder (screw diameter 20 mmφ) manufactured by Toyo Seiki Seisaku-sho, Ltd. at a cylinder temperature of 190°C and a screw rotation speed of 65 rpm to prepare pelletized polypropylene resin.

[0149] (7-2) Film molding method The film was produced using a small film forming device equipped with a slit die attached to a capillary rheometer as shown in Figures 1 to 5, and with a cooling roll 4, an air nozzle 5, and a take-up roll installed near the slit die. Specifically, the process is as follows.

[0150] The slit die was attached under the barrel of a capillary rheometer (Capillograph 1B, manufactured by Toyo Seiki Seisaku-sho, Ltd.) via an adapter joined to a clamping nozzle 1 and a joint part 2. A thermocouple for temperature measurement was attached to the slit die, and the capillary rheometer and the slit die were kept at the same temperature by using a plate heater in combination.

[0151] The sample (pellets) was fed into a capillary rheometer and melted. The sample was then extruded through a slit die into a film shape, and the film-like molten resin was solidified using a cooling roll and an air nozzle. The film was then collected using a take-up roll. The pellets used were 14 to 16 g, the barrel temperature was 190 to 200°C, the melting process time was 6 minutes, and the piston speed was 50 mm / min. The melted sample was extruded under these conditions.

[0152] The cooling roll 4 and air nozzle 5 were installed below the slit die and fixed so that the distance between the lower end of the slit die and the upper end of the cooling roll 4 was 10 mm. The air nozzle was 26 cm long and had 1 mm diameter air outlet holes at 5.5 mm intervals. The cooling air flow rate was 50 L / min. The cooled film was taken up by a take-up roll. The take-up speed was set to 1.0 to 1.4 m / min.

[0153] [Comparative Example 1] <Preparation of solid catalyst component (X-1)> (1) First step Using a 400 mL reactor equipped with a stirrer, 15 g of diethoxymagnesium (average particle size (APS-1) 45.0 μm, minimum particle size (APS-1(D0)) 22.7 μm ((APS-1(D0) / APS-1(D50): 50.4%), surface protrusion width 3 μm ((6.7% of APS(50)), 131.1 mmol)) was suspended in 120 mL of toluene under a nitrogen atmosphere, and then cooled to 10°C. While maintaining the temperature in the system at 10°C, 30 mL (273.6 mmol) of titanium tetrachloride was added dropwise to this suspension over 60 minutes. The temperature was then raised to 90°C, and 4.0 mL (15.1 mmol) of di-n-butyl phthalate was added. The temperature was further raised to 115°C, and the reaction was carried out with stirring for 2 hours while maintaining the temperature. The resulting reaction liquid was then allowed to stand, and the supernatant was removed to obtain a slurry-like reaction product.

[0154] To the above slurry-like reaction product, 150 mL of toluene at 90°C was added, stirred, allowed to stand, and then washed by removing the supernatant liquid three times to obtain a reaction product containing a slurry-like solid component (1).

[0155] (2) Second step To the reaction product containing the above-mentioned slurry-like solid component (1), 50 mL of toluene and 30 mL (273.6 mmol) of titanium tetrachloride were added, and the mixture was heated to 115°C and reacted with stirring for 2 hours. The resulting reaction liquid was then allowed to stand, and the supernatant was removed to obtain a slurry-like reaction product.

[0156] To the above slurry-like reaction product, 150 mL of toluene at 90°C was added, stirred, allowed to stand, and then washed by removing the supernatant liquid three times to obtain a reaction product containing a slurry-like solid component (2).

[0157] (3) The third step To the reaction product containing the above-mentioned slurry-like solid component (2), 250 mL of paraxylene, 7.3 mL (66.6 mmol) of titanium tetrachloride, and 1.0 mL (3.7 mmol) of diisobutyl phthalate were added, and the mixture was heated to 130°C and reacted with stirring for 1 hour. The resulting reaction liquid was then allowed to stand, and the supernatant was removed to obtain a slurry-like reaction product.

[0158] To the above slurry-like reaction product, 150 mL of decane at 100°C was added, followed by stirring and standing. After that, the supernatant was removed and the process was repeated four times for washing, thereby obtaining a reaction product (solid catalyst component (X-1)) containing a slurry-like solid component (3).

[0159] The resulting solid catalyst component (X-1) had a magnesium atom content of 21 mass %, a titanium atom content of 1.4 mass %, and a total content of phthalic acid diesters of 12.2 mass %.

[0160] <Preparation of propylene-based block copolymer for film evaluation> 500 g of propylene and 16 nL of hydrogen were added to a 2 L polymerization reactor equipped with a stirrer at room temperature. Then, 1.3 mmol of triethylaluminum, 0.27 mmol of diethylaminotriethoxysilane, and 0.004 mmol of the solid catalyst component (X-1) (titanium atom equivalent) were added. The mixture was quickly heated to 65 °C and polymerized at 65 °C for 30 minutes. Then, 0.2 mmol of triethylaluminum and 0.77 μmol of titanocene dichloride were added, and the pressure was released after 30 seconds. After depressurization, the gas ratio was adjusted to ethylene / (ethylene + propylene) = 43 mol%, and gas-phase polymerization was carried out at a total pressure of 0.4 MPa. Polymerization continued until the decane-soluble component content (Dsol) reached 10-11%. After completion of the reaction, the reaction was quenched with a small amount of ethanol, and the ethylene / propylene mixed gas was purged. The resulting white particles were then dried under reduced pressure at room temperature overnight to obtain sample (BP-1). The results are shown in Table 1. A large number of white spots were observed in the film formed using this polymer.

[0161] [Example 1] The diethoxymagnesium used in Comparative Example 1 was treated using a Labocruseal N-01 (treatment inner diameter: 0.19 m, treatment volume: approximately 4 L) manufactured by Seishin Enterprise Co., Ltd. 3.5 kg of the diethoxymagnesium particles described in Comparative Example 1 were continuously fed into and extracted from the apparatus over a period of 1 hour. Airflow treatment was carried out under conditions of a nitrogen flow rate of 1000 L / min, a gas outlet rotation speed of 1000 rpm, and a rotation diameter of 0.14 m, yielding airflow-treated diethoxymagnesium in 88% yield. No surface protrusions were observed under an electron microscope. The average particle diameter (APS-2(D50)) of the airflow-treated diethoxymagnesium was 48.1 μm (APS-2(D50) / APS-1(D50): 1.07).

[0162] A solid titanium catalyst component was prepared and polymerization was carried out in the same manner as in Comparative Example 1, except that the gas-flow-treated diethoxymagnesium was used, to obtain a propylene-based block copolymer. The results are shown in Table 1. Furthermore, almost no white spots were observed in the film formed using this polymer.

[0163] [Table 1] [Explanation of symbols]

[0164] A, B: Symbols indicating the direction of the cross section of the slit die. 1: Tightening nozzle 2: Joint part 3: Thermocouple insertion point for temperature measurement 4: Cooling roll 5: Air nozzle

Claims

1. a magnesium-containing compound (a); a titanium-containing compound (b); Optional Electron Donor (c) A method for producing a solid titanium catalyst component (A), comprising a step (Y) of contacting A method for producing a solid titanium catalyst component (A), further comprising a step (Z) of subjecting either or both of the particles containing the magnesium-containing compound (a) used in the step (Y) and the particles containing the solid titanium catalyst component obtained in the step (Y) to an airflow treatment that satisfies the following requirements (i) and (ii): (i) the average particle size (APS-1) (D50) is 30 to 70 μm; the minimum particle size (D0) is 30% or more and 70% or less of the average particle size (APS-1) (D50), The particles having protrusions on their surfaces with a value ranging from 1 to 15% of the average particle diameter (APS-1) (D50) are subjected to an air flow treatment; (ii) The average particle size (APS-2) (D50) of the particles after the airflow treatment (i) is 1.03 to 1.2 times the average particle size (APS-1).

2. A solid titanium catalyst component (A) obtained by the production method of claim 1; an organometallic compound (B); Optionally, an electron donor (C) a step (P1) of polymerizing an olefin including propylene in the presence of an olefin polymerization catalyst containing the above-mentioned olefin to produce polymer particles having a content of structural units derived from propylene of 90 mol % or more; a step (P2) of copolymerizing propylene with an olefin other than propylene in the presence of the polymer particles produced in the step (P1); A method for producing a propylene-based block copolymer comprising the steps of:

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