Polypropylene-based resin composition

Abstract

A polypropylene-based resin composition comprising a polypropylene-based resin (A) that includes a block polypropylene (A-1) composed of a continuous phase comprising a propylene polymer (A-1a) and a rubber phase comprising a copolymer (A-1b) of ethylene and propylene, an ethylene / α-olefin polymer (B) which is a polymer of ethylene and a C4-C10 α-olefin, an inorganic filler (C), and a stearate (D), wherein the block polypropylene (A-1) contains xylene solubles which have an intrinsic viscosity, as measured in 135°C tetrahydronaphthalene, of less than 4 dl / g.

Description

Polypropylene resin composition

[0001] The present invention relates to a polypropylene resin composition. This application claims priority to Japanese Patent Application No. 2024-148665, filed on August 30, 2024, the contents of which are incorporated herein by reference.

[0002] Polypropylene-based resin compositions containing polypropylene, ethylene-α-olefin copolymer, and inorganic filler are inexpensive and have excellent light weight, mechanical properties, and moldability, and are therefore widely used as molding materials for various molded articles. For example, the polypropylene-based resin compositions are used as molding materials for automobile exterior parts such as bumpers. Polypropylene-based resin compositions are sometimes required to produce molded articles with high rigidity and impact resistance. To meet this demand, polypropylene-based resin compositions containing block polypropylene, ethylene-α-olefin copolymer, and inorganic filler have been proposed (Patent Documents 1 to 5).

[0003] Japanese Patent Application Laid-Open No. 2000-178389 Japanese Patent Application Laid-Open No. 2001-181473 Japanese Patent Application Laid-Open No. 2008-239971 Japanese Patent Application Laid-Open No. 2008-545810 Japanese Patent Application Laid-Open No. 2015-113363

[0004] The present invention provides a polypropylene resin composition that can be used to form molded articles having excellent impact resistance at room temperature and at temperatures as low as -20°C (i.e., an excellent balance of physical properties) while maintaining high rigidity.

[0005] In order to achieve the above object, the present invention employs the following configuration: [1] A polypropylene-based resin composition containing a polypropylene-based resin (A) containing a block polypropylene (A-1) constituted by a continuous phase made of a propylene polymer (A-1a) and a rubber phase made of an ethylene-propylene copolymer (A-1b), an ethylene-α-olefin polymer (B) which is a polymer of ethylene and an α-olefin having 4 to 10 carbon atoms, an inorganic filler (C), and a stearate (D), wherein the block polypropylene (A-1) has a xylene-soluble portion having an intrinsic viscosity of less than 4 dl / g in tetrahydronaphthalene at 135°C, and the polypropylene-based resin (A) and the ethylene copolymer (A-1b) are copolymers of ethylene and propylene. a polypropylene-based resin composition in which, relative to 100 parts by mass of the total of the ethylene-α-olefin polymer (B) and the inorganic filler (C), the content of the polypropylene-based resin (A) is 20 to 80 parts by mass, the content of the ethylene-α-olefin polymer (B) is 10 to 40 parts by mass, the content of the inorganic filler (C) is 10 to 40 parts by mass, and the content of the stearate (D) is 0.17 to 2.0 parts by mass; and the total content of the polypropylene-based resin (A), the ethylene-α-olefin polymer (B), and the inorganic filler (C) relative to the total mass of the polypropylene-based resin composition is 90% by mass or more. [2] The polypropylene-based resin composition according to [1], wherein the polypropylene-based resin (A) further comprises a block polypropylene (A-2) composed of a continuous phase comprising a propylene polymer (A-2a) and a rubber phase comprising an ethylene-propylene copolymer (A-2b), and the block polypropylene (A-2) has an intrinsic viscosity of 4 to 11 dl / g in tetrahydronaphthalene at 135°C of a xylene-soluble portion. [3] The polypropylene-based resin composition according to [1] or [2], wherein the polypropylene-based resin (A) further comprises a propylene homopolymer (A-3), and the propylene homopolymer (A-3) has a melt flow rate of 2 to 2,000 g / 10 min measured under conditions of a temperature of 230°C and a load of 2.16 kg.[4] The polypropylene-based resin composition according to any one of [1] to [3], wherein the ethylene-α-olefin polymer (B) comprises an ethylene-α-olefin polymer (B-1) composed of ethylene and an α-olefin having 8 to 10 carbon atoms, and optionally an ethylene-α-olefin polymer (B-2) composed of ethylene and an α-olefin having 4 to 7 carbon atoms, and the content of the ethylene-α-olefin polymer (B-1) is 3 to 40 parts by mass and the content of the ethylene-α-olefin polymer (B-2) is 0 to 20 parts by mass relative to a total of 100 parts by mass of the polypropylene-based resin (A), the ethylene-α-olefin polymer (B), and the inorganic filler (C). [5] The polypropylene-based resin composition according to any one of [1] to [4], wherein the stearate (D) comprises magnesium stearate and calcium stearate, and the content of the magnesium stearate is 0.10 to 1.0 part by mass and the content of the calcium stearate is 0.07 to 1.0 part by mass relative to 100 parts by mass of the total of the polypropylene-based resin (A), the ethylene-α-olefin polymer (B), and the inorganic filler (C). [6] The polypropylene-based resin composition according to any one of [1] to [5], wherein the melt flow rate measured under conditions of a temperature of 230°C and a load of 2.16 kg is 35 g / 10 min or more.

[0006] The polypropylene resin composition of the present invention can form a molded article having excellent impact resistance at room temperature and at a low temperature of -20°C (i.e., an excellent balance of physical properties) while maintaining high rigidity.

[0007] <<Polypropylene-Based Resin Composition>> The polypropylene-based resin composition of the present embodiment contains a polypropylene-based resin (A) (hereinafter also referred to as component (A)), an ethylene-α-olefin polymer (B) (hereinafter also referred to as component (B)), which is a polymer of ethylene and an α-olefin having 4 to 10 carbon atoms, an inorganic filler (C) (hereinafter also referred to as component (C)), and a stearate (D) (hereinafter also referred to as component (D)).

[0008] The content of component (A) is 20 to 80 parts by mass relative to 100 parts by mass of the total of components (A), (B), and (C). The content of component (A) relative to 100 parts by mass of the total of components (A), (B), and (C) is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 55 parts by mass or more, and particularly preferably 60 parts by mass or more. Furthermore, the content is preferably 80 parts by mass or less, more preferably 75 parts by mass or less, even more preferably 70 parts by mass or less, and particularly preferably 65 parts by mass or less. That is, the content is preferably 40 to 80 parts by mass, more preferably 50 to 75 parts by mass, even more preferably 60 to 70 parts by mass, and particularly preferably 60 to 65 parts by mass. A content of component (A) of 20 parts by mass or more stabilizes production. A content of 80 parts by mass or less improves the balance of physical properties.

[0009] The content of component (B) is 10 to 40 parts by mass relative to a total of 100 parts by mass of components (A), (B), and (C). The content of component (B) relative to a total of 100 parts by mass of components (A), (B), and (C) is preferably 12 parts by mass or more, more preferably 14 parts by mass or more, and even more preferably 15 parts by mass or more. Furthermore, the content is preferably 30 parts by mass or less, more preferably 27 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less. That is, the content is preferably 12 to 30 parts by mass, more preferably 14 to 27 parts by mass, even more preferably 15 to 25 parts by mass, and particularly preferably 15 to 20 parts by mass. When the content of component (B) is 10 parts by mass or more, the Izod impact strength increases. When the content is 40 parts by mass or less, the rigidity improves.

[0010] The content of component (C) is 10 to 40 parts by mass relative to a total of 100 parts by mass of components (A), (B), and (C). The content of component (C) relative to a total of 100 parts by mass of components (A), (B), and (C) is preferably 12 parts by mass or more, more preferably 14 parts by mass or more, and even more preferably 15 parts by mass or more. It is also preferably 32 parts by mass or less, more preferably 27 parts by mass or less, and even more preferably 25 parts by mass or less. That is, 12 to 32 parts by mass is preferred, 14 to 27 parts by mass is more preferred, and 15 to 25 parts by mass is even more preferred. An even more preferred range is 18.5 to 22.5 parts by mass. When the content of component (C) is 10 parts by mass or more, desirable rigidity can be obtained. When it is 40 parts by mass or less, Izod impact strength is increased.

[0011] The content of component (D) is 0.17 to 2.0 parts by mass relative to 100 parts by mass of the total of components (A), (B), and (C). The content of component (D) relative to 100 parts by mass of the total of components (A), (B), and (C) is preferably 0.18 parts by mass or more, more preferably 0.19 parts by mass or more, and even more preferably 0.20 parts by mass or more. It is also preferably 1.5 parts by mass or less, more preferably 1.0 parts by mass or less, and even more preferably 0.5 parts by mass or less. That is, it is preferably 0.18 to 1.5 parts by mass, more preferably 0.19 to 1.0 parts by mass, and even more preferably 0.20 to 0.5 parts by mass. An even more preferred range is 0.40 to 0.50 parts by mass. By having the content of component (D) 0.17 parts by mass or more, a desirable balance of physical properties can be obtained while maintaining fluidity. By having the content 2.0 parts by mass or less, the balance of physical properties is improved.

[0012] The total content of components (A), (B), and (C) relative to the total mass of the polypropylene resin composition of this embodiment is 90% by mass or more, preferably 94% by mass or more, more preferably 96% by mass or more, and even more preferably 98% by mass or more. It is also preferably 99.8% by mass or less, more preferably 99.5% by mass or less, and even more preferably 99.4% by mass or less. That is, it is preferably 94 to 99.8 parts by mass, more preferably 96 to 99.5 parts by mass, and even more preferably 98 to 99.4 parts by mass.

[0013] <Polypropylene-Based Resin (A)> In this specification and claims, polypropylene-based resin (A) refers to a resin containing propylene-derived units as a main component. "Containing propylene-derived units as a main component" means that the proportion of propylene-derived units in all units constituting the resin is 50% by mass or more. The polypropylene-based resin (A) (hereinafter also referred to as component (A)) contained in the polypropylene-based resin composition of this embodiment contains a block polypropylene (A-1) (hereinafter also referred to as component (A-1)). Component (A) may further contain a block polypropylene (A-2) (hereinafter also referred to as component (A-2)). Component (A) may further contain a propylene homopolymer (A-3) (hereinafter also referred to as component (A-3)). The total mass of components (A-1), (A-2), and (A-3) relative to the total mass of component (A) is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass.

[0014] [Block Polypropylene (A-1)] The block polypropylene (A-1) (component (A-1)) is composed of a continuous phase made of a propylene polymer (A-1a) (hereinafter also referred to as component (A-1a)) and a rubber phase made of an ethylene-propylene copolymer (A-1b) (hereinafter also referred to as component (A-1b)). Component (A-1) is one embodiment of impact-resistant polypropylene polymers specified in JIS K6921-1.

[0015] Component (A-1) may be a mixed resin obtained by mixing components (A-1a) and (A-1b) as a result of polymerization, or a mixed resin obtained by mixing components (A-1a) and (A-1b) obtained separately by melt-kneading. A mixture (polymerization mixture) of components (A-1a) and (A-1b) as a result of polymerization is preferred, as it provides an excellent balance of rigidity, low-temperature impact resistance, and tensile properties (hereinafter also referred to as mechanical property balance) at a lower cost.

[0016] In the polymerization mixture, component (A-1a) and component (A-1b) can be mixed at the submicron level, and thus polypropylene resin compositions based on the polymerization mixture exhibit an excellent balance of mechanical properties. On the other hand, if a similar uniform mixture is achieved by simply melt-kneading separately obtained components (A-1a) and (A-1b) to obtain an excellent balance of mechanical properties, production costs will be high due to the need for additional steps such as storage, keeping, transport, weighing, mixing, and melt-kneading. This is also undesirable from the viewpoint of energy costs.

[0017] The reason why the polymerization mixture and the mechanical mixture may exhibit different physical properties is presumably due to differences in the dispersion states of component (A-1a) and component (A-1b), but no practical means is currently known for analyzing the dispersion state at the molecular level, including the state of the interface between component (A-1b) and component (A-1a). The production method of component (A-1) will be described in detail later.

[0018] The weight average molecular weight M, which is an index of the molecular weight distribution of component (A-1a) constituting component (A-1), ｗ and number average molecular weight M ｎ Ratio to (M ｗ / M ｎ ) is preferably 9 or less, more preferably 8 or less, and even more preferably less than 7. When it is in the above preferred range, the Izod impact strength increases. The lower limit of the above ratio is not particularly limited, and a rough guideline is, for example, 3 or more. That is, it is preferably 3 or more and 9 or less, more preferably 3 or more and 8 or less, and even more preferably 3 or more and less than 7. Here, the weight average molecular weight M ｗ and number average molecular weight M ｎ is a value measured by the method described in WO 2022 / 270629.

[0019] The content of ethylene-derived units in component (A-1a) is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, based on the total mass of component (A-1a). When the content of ethylene-derived units in component (A-1a) is equal to or less than the above-mentioned preferred upper limit, the rigidity of the molded article is increased. There is no particular lower limit for the content of ethylene-derived units in component (A-1a), and it may be 0% by mass.

[0020] That is, the component (A-1a) is preferably a polypropylene homopolymer consisting of only propylene-derived units, or a copolymer consisting of 99.5% by mass or more but less than 100% by mass of propylene-derived units and more than 0% by mass but not more than 0.5% by mass of ethylene-derived units. １３ It is measured by C-NMR method.

[0021] Component (A-1b) constituting component (A-1) is a copolymer having ethylene-derived units and propylene-derived units. The content of ethylene-derived units in component (A-1b) is preferably 20% by mass or more, more preferably 22% by mass or more, even more preferably 24% by mass or more, and particularly preferably 25% by mass or more, relative to the total mass of component (A-1b). It is also preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less. That is, it is preferably 20 to 50% by mass, more preferably 22 to 40% by mass, even more preferably 24 to 35% by mass, and particularly preferably 25 to 30% by mass.

[0022] When the content of ethylene-derived units in component (A-1b) is equal to or greater than the lower limit of the preferred range, the Izod impact strength increases. When the content is equal to or less than the upper limit of the preferred range, a desirable shrinkage percentage is obtained. The content of ethylene-derived units in component (A-1b) is １３ It is measured by C-NMR method.

[0023] Component (A-1) is preferably a component (A-1b) in which the ethylene-derived unit content is 20 to 40 mass% (hereinafter also referred to as component (A-11)). Component (A-1) may also contain a component (A-1b) in which the ethylene-derived unit content is not 20 to 40 mass% (hereinafter referred to as component (A-12)). The proportion of component (A-1) in component (A-1) is preferably 90 mass% or more, more preferably 95 mass% or more, and particularly preferably 100 mass%.

[0024] The content of component (A-1b) relative to the total mass of component (A-1) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. It is also preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less. That is, it is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, even more preferably 20 to 30% by mass, and particularly preferably 20 to 25% by mass.

[0025] When the content of component (A-1b) relative to the total mass of component (A-1) is at least the lower limit of the preferred range, the impact resistance of the molded article is enhanced. When the content is at most the upper limit of the preferred range, the risk of flow path clogging in production equipment due to deterioration of powder fluidity during production of component (A-1) is reduced, allowing for stable continuous production of component (A-1).

[0026] Depending on the content of component (A-1b), the content of component (A-1a) relative to the total mass of component (A-1) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 75% by mass or more. Also, it is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. That is, it is preferably 50 to 90% by mass, more preferably 60 to 85% by mass, even more preferably 70 to 80% by mass, and particularly preferably 75 to 80% by mass.

[0027] The xylene-soluble fraction of component (A-1) (the main component of which is component (A-1b)) has an intrinsic viscosity (hereinafter also referred to as XSIV) in tetrahydronaphthalene at 135°C of less than 4 dl / g, preferably 3.5 dl / g or less, more preferably 3.0 dl / g or less, and even more preferably 2.6 dl / g or less. Furthermore, the XSIV of component (A-1) is preferably 1.5 dl / g or more, more preferably 2.0 dl / g or more. That is, it is preferably 1.5 to 3.5 dl / g, more preferably 2.0 to 3.0 dl / g, and even more preferably 2.0 to 2.6 dl / g.

[0028] Here, XSIV is a value measured by the method described below. When the XSIV of component (A-1) is less than 4 dl / g, the dart impact strength is increased. When the XSIV of component (A-1) is equal to or greater than the lower limit of the above-mentioned preferred range, the Izod impact strength is increased.

[0029] The melt flow rate (hereinafter also referred to as MFR) of component (A-1) at a temperature of 230°C and a load of 2.16 kg is preferably 5 g / 10 min or more, more preferably 10 g / 10 min or more, even more preferably 20 g / 10 min or more, particularly preferably 40 g / 10 min or more, and most preferably 100 g / 10 min or more. It is also preferably 300 g / 10 min or less, more preferably 200 g / 10 min or less, and even more preferably 150 g / 10 min or less. That is, it is preferably 5 to 300 g / 10 min, more preferably 10 to 200 g / 10 min, even more preferably 20 to 150 g / 10 min, particularly preferably 40 to 150 g / 10 min, and most preferably 100 to 150 g / 10 min. Here, MFR is a value measured by the measurement method described below.

[0030] When the MFR of component (A-1) is at least the lower limit of the preferred range, the moldability is excellent. It is generally difficult to adjust the MFR to less than 0.1 g / 10 min during production. When the MFR is at most the upper limit of the range, the impact resistance is enhanced and the production stability of the resin is improved.

[0031] The content of component (A-1) relative to the total mass of component (A) is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, particularly preferably 24% by mass or more, and most preferably 30% by mass or more. It is also preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. That is, it is preferably 5 to 80% by mass, more preferably 15 to 70% by mass, even more preferably 20 to 60% by mass, particularly preferably 24 to 60% by mass, and most preferably 30 to 60% by mass. By having the content of component (A-1) at or above the lower limit of the above preferred range, the amount of component (B) added can be reduced while maintaining impact resistance, improving economic efficiency. By having the content of component (A-1) at or below the upper limit of the above preferred range, there is room for adding component (B), allowing for improved impact resistance.

[0032] [Block Polypropylene (A-2)] The block polypropylene (A-2) (component (A-2)) is composed of a continuous phase made of a propylene polymer (A-2a) (hereinafter also referred to as component (A-2a)) and a rubber phase made of an ethylene-propylene copolymer (A-2b) (hereinafter also referred to as component (A-2b)). Component (A-2) is one embodiment of impact-resistant polypropylene polymers specified in JIS K6921-1.

[0033] The preferred embodiments of component (A-2a) constituting component (A-2) are basically the same as the preferred embodiments of component (A-1a) above, but due to the different function required of component (A-2) from component (A-1), some of them differ from the preferred embodiments of component (A-1a), as described below. Also, component (A-2b) constituting component (A-2) is a copolymer having ethylene-derived units and propylene-derived units, and is basically the same as the preferred embodiments of component (A-1b) above, but due to the different function required of component (A-2) from component (A-1), some of them differ from the preferred embodiments of component (A-1b), as described below.

[0034] The weight average molecular weight M, which is an index of the molecular weight distribution of component (A-2a) constituting component (A-2), ｗ and number average molecular weight M ｎRatio to (M ｗ / M ｎ ) is preferably 6 to 20, more preferably 7 to 20, even more preferably 8 to 20, and particularly preferably 9 to 20. When Mw / Mn, an index of molecular weight distribution, is in this wide range of 6 to 20, improvement in die swell due to the high molecular weight component can be achieved while maintaining fluidity. When the die swell is large, the molten polymer quickly contacts the mold during molding, resulting in a good appearance.

[0035] The xylene-soluble portion of component (A-2) (main component is component (A-2b)) has an intrinsic viscosity (XSIV) in tetrahydronaphthalene at 135°C of 4 to 11 dl / g. Having an XSIV within this range increases die swell, resulting in a polypropylene-based resin composition with a good appearance during molding. The XSIV of component (A-2) is preferably 10 dl / g or less, more preferably 9 dl / g or less, and particularly preferably 8 dl / g or less. The XSIV of component (A-2) is preferably 5 dl / g or more, more preferably 5.5 dl / g or more, and even more preferably 6.5 dl / g or more. That is, 5 to 10 dl / g is preferred, 5.5 to 9 dl / g is more preferred, and 6.5 to 8 dl / g is even more preferred.

[0036] Other than the above, preferred aspects of component (A-2) are the same as those of component (A-1). When component (A) contains component (A-2) in addition to component (A-1), the content of component (A-2) relative to the total mass of component (A) is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, and most preferably 25% by mass or more. Also, it is preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, particularly preferably 40% by mass or less, and most preferably 30% by mass or less. That is, it is preferably 5 to 60% by mass, more preferably 10 to 55% by mass, even more preferably 15 to 50% by mass, particularly preferably 20 to 40% by mass, and most preferably 25 to 30% by mass. By having the content of component (A-2) equal to or greater than the lower limit of the above preferred range, defects in appearance are reduced. By ensuring that the content is equal to or less than the upper limit of the above preferred range, gel formation in the composition is reduced and dart impact strength is increased.

[0037] When component (A) contains component (A-2) and component (A-3) described below in addition to component (A-1), the content of component (A-2) relative to the total mass of component (A) is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, and most preferably 25% by mass or more. Also, it is preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, particularly preferably 45% by mass or less, particularly preferably 40% by mass or less, and most preferably 30% by mass or less. That is, it is preferably 5 to 60% by mass, more preferably 10 to 55% by mass, even more preferably 15 to 50% by mass, particularly preferably 15 to 45% by mass, particularly preferably 20 to 40% by mass, and most preferably 25 to 30% by mass. By having the content of component (A-2) at or above the lower limit of the above preferred range, defects in appearance are reduced. By ensuring that the content is equal to or less than the upper limit of the above preferred range, gel formation in the composition is reduced and dart impact strength is increased.

[0038] [Propylene Homopolymer (A-3)] The propylene homopolymer (A-3) (component (A-3)) is a homopolymer composed only of propylene-derived units.

[0039] The melt flow rate (MFR) of component (A-3) at a temperature of 230°C and a load of 2.16 kg is preferably 15 g / 10 min or more, more preferably 20 g / 10 min or more, and even more preferably 25 g / 10 min or more. It is also preferably 4000 g / 10 min or less, more preferably 3000 g / 10 min or less, and even more preferably 2000 g / 10 min or less. That is, it is preferably 15 to 4000 g / 10 min, more preferably 20 to 3000 g / 10 min, and even more preferably 25 to 2000 g / 10 min. Here, MFR is a value measured by the measurement method described below. When the MFR of component (A-3) is equal to or greater than the lower limit of the preferred range, excellent moldability and desirable morphology are obtained. When it is equal to or less than the upper limit of the range, Izod impact strength increases.

[0040] When component (A) contains component (A-3) in addition to component (A-1), the content of component (A-3) relative to the total mass of component (A) is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, particularly preferably 10% by mass or more, even more preferably 15% by mass or more, and most preferably 20% by mass or more. It is also preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, particularly preferably 55% by mass or less, and most preferably 50% by mass or less. That is, it is preferably 1 to 70% by mass, more preferably 2 to 65% by mass, even more preferably 3 to 60% by mass, particularly preferably 10 to 55% by mass, even particularly preferably 15 to 55% by mass, and most preferably 20 to 50% by mass. When the content of component (A-3) is at least the lower limit of the above-mentioned preferred range, it becomes easier to adjust the MFR of the composition and maintain its rigidity. When it is at most the upper limit of the above-mentioned preferred range, it becomes easier to maintain impact resistance.

[0041] When component (A) contains component (A-2) and component (A-3) in addition to component (A-1), the content of component (A-3) relative to the total mass of component (A) is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, particularly preferably 10% by mass or more, particularly preferably 15% by mass or more, and most preferably 20% by mass or more. Also, it is preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less, and particularly preferably 35% by mass or less. That is, it is preferably 1 to 50% by mass, more preferably 2 to 45% by mass, even more preferably 3 to 40% by mass, particularly preferably 10 to 35% by mass, particularly preferably 15 to 35% by mass, and most preferably 20 to 35% by mass. When the content of component (A-3) is at least the lower limit of the above-mentioned preferred range, it becomes easier to adjust the MFR of the composition and maintain its rigidity. When it is at most the upper limit of the above-mentioned preferred range, it becomes easier to maintain impact resistance.

[0042] <Ethylene-α-olefin polymer (B)> The ethylene-α-olefin polymer (B) (hereinafter also referred to as component (B)) contained in the polypropylene resin composition of this embodiment is a polymer of ethylene and an α-olefin having 4 to 10 carbon atoms. Component (B) preferably contains an ethylene-α-olefin polymer (B-1) (hereinafter also referred to as component (B-1)) made of ethylene and an α-olefin having 8 to 10 carbon atoms. Component (B) may also contain an ethylene-α-olefin polymer (B-2) (hereinafter also referred to as component (B-2)) made of ethylene and an α-olefin having 4 to 7 carbon atoms.

[0043] [Ethylene / α-olefin polymer (B-1)] Examples of the α-olefin having 8 to 10 carbon atoms that constitutes the ethylene / α-olefin polymer (B-1) (component (B-1)) include 1-octene and 1-decene. Of these, 1-octene is preferred.

[0044] The density of component (B-1) is 0.800 g / cm ３ More preferably, 0.820 g / cm ３ More preferably, 0.840 g / cm or more ３ More preferably, 0.850 g / cm ３ More preferably, the density is 0.885 g / cm or more. ３ Preferably, 0.880 g / cm or less ３ More preferably, 0.875 g / cm ３ More preferably, the density is 0.800 to 0.885 g / cm ３ is preferably 0.820 to 0.880 g / cm ３ More preferably, 0.840 to 0.875 g / cm ３ is more preferably 0.850 to 0.875 g / cm ３ When the density of component (B-1) is within the preferred range, the Izod impact strength increases while maintaining rigidity.

[0045] The MFR of component (B-1) at a temperature of 190°C and a load of 2.16 kg is preferably 0.2 g / 10 min or more, more preferably 0.3 g / 10 min or more, even more preferably 0.4 g / 10 min or more, and particularly preferably 0.5 g / 10 min or more. It is also preferably 60 g / 10 min or less, more preferably 20 g / 10 min or less, even more preferably 10 g / 10 min or less, particularly preferably 5.0 g / 10 min or less, and most preferably 1.0 g / 10 min or less. That is, it is preferably 0.2 to 60 g / 10 min, more preferably 0.3 to 20 g / 10 min, even more preferably 0.4 to 10 g / 10 min, particularly preferably 0.5 to 5.0 g / 10 min, and most preferably 0.5 to 1.0 g / 10 min. Here, the MFR is a value measured by the measurement method described below.

[0046] The content of component (B-1) relative to the total mass of component (B) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, particularly preferably 30% by mass or more, and most preferably 33% by mass or more. Here, the upper limit of the content of component (B-1) may be 100% by mass, but is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less. That is, 10 to 80% by mass is preferred, more preferably 20 to 60% by mass, even more preferably 25 to 40% by mass, particularly preferably 30 to 40% by mass, and most preferably 33 to 40% by mass. Impact resistance is improved when the content of component (B-1) is at or above the lower limit of the above preferred range. Izod impact strength, particularly at -20°C, is improved when the content is at or below the upper limit of the above preferred range.

[0047] The content of component (B-1) relative to 100 parts by mass of the total of component (A), component (B), and component (C) is preferably 3 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 5 parts by mass or more. It is also 40 parts by mass or less, preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, and most preferably 10 parts by mass or less. That is, 3 to 40 parts by mass is preferred, also preferably 3 to 30 parts by mass, more preferably 4 to 25 parts by mass, more preferably 5 to 20 parts by mass, particularly preferably 5 to 15 parts by mass, and most preferably 5 to 10 parts by mass. When the content of component (B-1) is at least the lower limit of the preferred range, the Izod impact strength increases. When it is 40 parts by mass or less, the rigidity improves. When it is at most the upper limit of the above preferred range, the Izod impact strength, particularly at -20°C, is improved.

[0048] [Ethylene / α-olefin polymer (B-2)] Examples of the α-olefin having 4 to 7 carbon atoms that constitutes the ethylene / α-olefin polymer (B-2) (component (B-2)) include 1-butene, 1-pentene, and 1-hexene. Of these, 1-butene is preferred.

[0049] The density of component (B-2) is 0.800 g / cm ３ More preferably, 0.820 g / cm ３ More preferably, 0.840 g / cm or more ３ More preferably, 0.850 g / cm ３ More preferably, the viscosity is 0.880 g / cm or more. ３ Preferably, 0.870 g / cm or less ３ More preferably, 0.865 g / cm ３ More preferably, the following is true: 0.800 to 0.880 g / cm ３ is preferably 0.820 to 0.870 g / cm ３ More preferably, 0.840 to 0.865 g / cm ３ is more preferably 0.850 to 0.865 g / cm ３ When the density of component (B-2) is within the preferred range, the Izod impact strength increases while maintaining rigidity.

[0050] The MFR of component (B-2) at a temperature of 190°C and a load of 2.16 kg is preferably 0.2 g / 10 min or more, more preferably 0.5 g / 10 min or more, and even more preferably 0.8 g / 10 min or more. It is also preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, and even more preferably 5 g / 10 min or less. That is, it is preferably 0.2 to 20 g / 10 min, more preferably 0.5 to 10 g / 10 min, and even more preferably 0.8 to 5 g / 10 min. Here, the MFR is a value measured by the measurement method described below.

[0051] The content of component (B-2) relative to the total mass of component (B) is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and particularly preferably 70% by mass or less. Here, the lower limit of the content of component (B-2) may be 0% by mass, but is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more. That is, 10 to 90% by mass is preferred, more preferably 30 to 80% by mass, even more preferably 50 to 75% by mass, and particularly preferably 60 to 70% by mass. When the content of component (B-2) is equal to or less than the upper limit of the above-mentioned preferred range, the morphology of the composition is improved. When the content is equal to or greater than the lower limit of the above-mentioned preferred range, the Izod impact strength, particularly at -20°C, is improved.

[0052] The content of component (B-2) relative to 100 parts by mass of the total of components (A), (B), and (C) is preferably 20 parts by mass or less, more preferably 17 parts by mass or less, and even more preferably 15 parts by mass or less. It is also preferably 3 parts by mass or more, more preferably 6 parts by mass or more, and even more preferably 10 parts by mass or more. That is, it is preferably 3 to 20 parts by mass, more preferably 6 to 17 parts by mass, and even more preferably 10 to 15 parts by mass. When the content of component (B-2) is equal to or less than the upper limit of the above-mentioned preferred range, there is room for improving the balance of physical properties by using a higher-performance polymer such as component (B-1). When the content is equal to or greater than the lower limit of the above-mentioned preferred range, the Izod impact strength, particularly at -20°C, is improved.

[0053] <Inorganic Filler (C)> Examples of the inorganic filler (C) (hereinafter also referred to as component (C)) contained in the polypropylene resin composition of the present embodiment include natural silicic acid or silicate salts such as talc, kaolinite, clay, pylophyllite, selinite, wollastonite, and mica; synthetic silicic acid or silicate salts such as hydrous calcium silicate, hydrous aluminum silicate, hydrous silicic acid, and silicic anhydride; carbonates such as precipitated calcium carbonate, heavy calcium carbonate, and magnesium carbonate; hydroxides such as aluminum hydroxide and magnesium hydroxide; and oxides such as zinc oxide and magnesium oxide.

[0054] Examples of component (C) in terms of shape include the following: powdery fillers such as synthetic silicic acids or silicates, such as hydrous calcium silicate, hydrous aluminum silicate, hydrous silicic acid, and anhydrous silicic acid; plate-like fillers such as talc, kaolinite, clay, and mica; whisker-like fillers such as basic magnesium sulfate whiskers, calcium titanate whiskers, aluminum borate whiskers, sepiolite, PMF (Processed Mineral Filler), xonotlite, potassium titanate, and ellestadite; balloon-like fillers such as glass balloons and fly ash balloons; and fibrous fillers such as glass fibers.

[0055] One type of component (C) may be used, or two or more types may be used in combination. To improve the dispersibility of component (C), component (C) may be surface-treated as needed. The inorganic filler used as component (C) is not limited, but a plate-like inorganic filler is preferred from the viewpoint of promoting the orientation of polypropylene crystals in the injection-molded article and thereby improving the balance of mechanical properties. Known plate-like inorganic fillers such as talc, kaolinite, clay, and mica can be used as the plate-like inorganic filler. Considering the affinity with polypropylene resins, ease of procurement as a raw material, and economic efficiency, talc and mica are preferred, and talc is more preferred.

[0056] The volume average particle diameter of component (C) is preferably 1 to 10 μm, more preferably 2 to 7 μm. When the volume average particle diameter is within this range, the balance of mechanical properties of the injection-molded article is improved. The volume average particle diameter can be measured as the 50% diameter in the cumulative volume fraction by laser diffraction (based on JIS R1629).

[0057] <Stearate (D)> The stearate (D) (component (D)) contained in the polypropylene resin composition of this embodiment is a metal salt of stearic acid, i.e., a metal soap. Metals constituting the salt include magnesium, calcium, zinc, and aluminum, which are metals other than alkali metals. As component (D), magnesium stearate and calcium stearate are preferred, and a combination of magnesium stearate and calcium stearate is particularly preferred.

[0058] When magnesium stearate and calcium stearate are used in combination, the content of magnesium stearate per 100 parts by mass of the total of components (A), (B), and (C) is preferably 0.10 parts by mass or more, more preferably 0.15 parts by mass or more, and even more preferably 0.20 parts by mass or more. Also, it is preferably 1.0 part by mass or less, more preferably 0.70 parts by mass or less, even more preferably 0.50 parts by mass or less, and particularly preferably 0.30 parts by mass or less. That is, it is preferably 0.10 to 1.0 part by mass, more preferably 0.15 to 0.70 parts by mass, even more preferably 0.15 to 0.50 parts by mass, particularly preferably 0.15 to 0.30 parts by mass, and most preferably 0.20 to 0.30 parts by mass. By having a magnesium stearate content of 0.10 parts by mass or more, Izod impact strength is increased. By having a magnesium stearate content of 1.0 part by mass or less, rigidity is improved.

[0059] Furthermore, when magnesium stearate and calcium stearate are used in combination, the content of calcium stearate relative to 100 parts by mass of the total of components (A), (B), and (C) is preferably 0.07 parts by mass or more, more preferably 0.09 parts by mass or more, and even more preferably 0.11 parts by mass or more. Furthermore, it is preferably 1.0 part by mass or less, more preferably 0.7 parts by mass or less, and even more preferably 0.5 parts by mass or less. A calcium stearate content of 0.07 parts by mass or more increases Izod impact strength. A calcium stearate content of 1.0 part by mass or less improves rigidity. Additionally, from the viewpoint of improving Izod impact strength at −20° C., the content is preferably 0.07 to 1.0 part by mass, more preferably 0.09 to 0.5 parts by mass, even more preferably 0.09 to 0.35 parts by mass, particularly preferably 0.09 to 0.25 parts by mass, and most preferably 0.11 to 0.25 parts by mass. From the same viewpoint, it is also preferable that the content of magnesium stearate is greater than the content of calcium stearate.

[0060] The content of component (D) is 0.17 to 2.0 parts by mass relative to 100 parts by mass of the total of components (A), (B), and (C). The content of component (D) relative to 100 parts by mass of the total of components (A), (B), and (C) is preferably 0.18 parts by mass or more, more preferably 0.24 parts by mass or more, and even more preferably 0.30 parts by mass or more. It is also preferably 1.5 parts by mass or less, more preferably 1.0 parts by mass or less, and even more preferably 0.60 parts by mass or less. That is, it is preferably 0.18 to 1.50 parts by mass, more preferably 0.24 to 1.00 parts by mass, even more preferably 0.24 to 0.60 parts by mass, and particularly preferably 0.30 to 0.60 parts by mass. When the content of component (D) is 0.17 parts by mass or more, the Izod impact strength increases. When it is 2.0 parts by mass or less, the rigidity improves.

[0061] <Other Components> The polypropylene resin composition of the present embodiment may contain, as optional components, synthetic resins or synthetic rubbers other than component (A) and component (B) or additives in addition to component (A), component (B), component (C), and component (D), as long as the effects of the present invention are not impaired.

[0062] Examples of the additives include antioxidants, hydrochloric acid absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, slip agents, antistatic agents, flame retardants, dispersants, copper inhibitors, neutralizing agents, plasticizers, foaming agents, bubble inhibitors, crosslinking agents, and peroxides. These additives may be used alone or in combination of two or more. The content may be a known amount.

[0063] <Physical Properties of the Overall Composition> The melt flow rate of the polypropylene resin composition of this embodiment, measured at a temperature of 230°C and a load of 2.16 kg, is preferably 35 g / 10 min or more, more preferably 36 g / 10 min or more, and even more preferably 37 g / 10 min or more. It is also preferably 80 g / 10 min or less, more preferably 60 g / 10 min or less, even more preferably 50 g / 10 min or less, and particularly preferably 45 g / 10 min. That is, it is preferably 35 to 80 g / 10 min, more preferably 36 to 60 g / 10 min, even more preferably 37 to 50 g / 10 min, and particularly preferably 37 to 45 g / 10 min. Here, the MFR is a value measured by the measurement method described below.

[0064] When the MFR of the entire composition is equal to or greater than the lower limit of the preferred range, the moldability is excellent. It is generally difficult to adjust the MFR to less than 0.1 g / 10 min when producing a molded article. When the MFR is equal to or less than the upper limit of the range, the impact resistance of the molded article is improved. The MFR of the entire composition can be adjusted by changing the MFR of the component (A), component (B), and / or component (C) used, or by changing the compounding ratio.

[0065] The density of the polypropylene resin composition of this embodiment is 1.2 g / cm ３ Preferably, 1.1 g / cm or less ３ More preferably, 1.07 g / cm or less ３ More preferably, the density is 1.00 g / cm or less. ３ That is, it is preferably 1.00 to 1.20 g / cm ３ is preferred, and 1.00 to 1.10 g / cm ３ More preferably, 1.00 to 1.07 g / cm ３Here, the density is a value measured under conditions of 23°C ± 2°C in accordance with JIS K6922-1:2018. The density of the polypropylene resin composition of the present embodiment can be adjusted by changing the amount of the inorganic filler (C).

[0066] <<Method for Producing Polypropylene-Based Resin Composition>> Examples of a method for producing the polypropylene-based resin composition of the present embodiment include a method of mixing a polypropylene-based resin (A) (component (A)), an ethylene-α-olefin polymer (B) (component (B)) which is a polymer of ethylene and an α-olefin having 4 to 10 carbon atoms, an inorganic filler (C) (component (C)), a stearate (D) (component (D)), and, if necessary, other components, followed by melt-kneading.

[0067] Examples of mixing methods include dry blending using a mixer such as a Henschel mixer, a tumbler, or a ribbon mixer. Examples of melt-kneading methods include mixing while melting using a mixer such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader, or a roll mill. The melting temperature during melt-kneading is preferably 160 to 350°C, and more preferably 170 to 260°C. After melt-kneading, the mixture may be further pelletized.

[0068] Component (C) may be dry-blended with pellets containing at least one of component (A) and component (B). The dry-blended component (C) is uniformly mixed with molten components (A) and (B) when molding the polypropylene resin composition.

[0069] A so-called masterbatch, which is prepared by melt-kneading a high concentration of component (C) with a resin component, may be added to at least one of component (A) and component (B) and melt-kneaded, or may be dry-blended with pellets containing at least one of component (A) and component (B). In this case, the proportions of the resin components contained in the masterbatch and the amount of the masterbatch added are adjusted so that the resin components contained in the masterbatch do not affect the physical properties of the polypropylene resin composition.

[0070] The content of the resin component contained in the masterbatch is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, relative to the total mass of the polypropylene-based resin composition of this embodiment. Within the above preferred range, the resin component contained in the masterbatch can be prevented from adversely affecting the physical properties of the polypropylene-based resin composition. The type of resin component is not limited, but an olefin-based resin is preferred in consideration of its affinity with the polypropylene-based resin and ethylene-α-olefin copolymer that constitute the composition.

[0071] The content of the masterbatch is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less, relative to 100 parts by mass of the total of component (A) and component (B). When the content is within the above preferred range, rigidity can be increased without impairing moldability or impact resistance.

[0072] <Method for producing polypropylene-based resin (A)> As described above, polypropylene-based resin (A) (component (A)) contains component (A-1) and, if necessary, further contains one or both of component (A-2) and component (A-3). When component (A) contains one or both of component (A-2) and component (A-3) in addition to component (A-1), component (A) is obtained by mixing these components, which have been produced separately, by melt-kneading.

[0073] [Production Method of Component (A-1)] The production method of component (A) will be described below, mainly using (A-1) as an example, but some description of the production methods of components (A-2) and (A-3) will also be included. Component (A-1) may be obtained by mixing separately obtained components (A-1a) and (A-1b) by melt-kneading, but it is preferable to obtain it as a mixed resin in which components (A-1a) and (A-1b) are mixed as a result of polymerization. Specifically, it can be obtained by polymerizing ethylene monomer and propylene monomer in the presence of component (A-1a). This method not only increases productivity but also improves the dispersibility of component (A-1b) in component (A-1a), thereby improving the balance of mechanical properties of molded articles obtained using this.

[0074] A multi-stage polymerization method is typically used to polymerize ethylene monomer and propylene monomer in the presence of component (A-1a). For example, component (A-1a) is obtained by polymerizing propylene monomer and, if necessary, a small amount of ethylene monomer in the first-stage polymerization reactor of a polymerization apparatus equipped with two-stage polymerization reactors. Next, the obtained component (A-1a) is supplied to a second-stage polymerization reactor, and ethylene monomer and propylene monomer are polymerized in this second-stage polymerization reactor, thereby obtaining component (A-1).

[0075] The polymerization conditions may be the same as known polymerization conditions. For example, a first-stage polymerization method may be a slurry polymerization method in which the propylene monomer is present in a liquid phase, and which has high monomer density and productivity. A second-stage polymerization method may be a gas-phase polymerization method, which generally facilitates the production of a copolymer having high solubility in a propylene polymer.

[0076] The polymerization temperature throughout the first and second stages is preferably 50 to 90°C, more preferably 60 to 90°C, and even more preferably 70 to 90°C. When the polymerization temperature is equal to or higher than the lower limit of the above range, the productivity and the stereoregularity of the obtained component (A-1a) are better. The polymerization pressure for the first stage, which is carried out in a liquid phase, is preferably 5 to 60 bar (2.5 to 6.0 MPa), more preferably 33 to 45 bar (3.3 to 4.5 MPa). For the second stage, which is carried out in a gas phase, it is preferably 5 to 30 bar (0.5 to 3.0 MPa), more preferably 8 to 30 bar (0.8 to 3.0 MPa).

[0077] The polymerization is usually carried out using a catalyst. During the polymerization, hydrogen may be added, if necessary, to adjust the molecular weight. By adjusting the molecular weight of component (A-1a) or component (A-1b), the MFR of component (A-1) and, ultimately, the MFR of the polypropylene resin composition can be adjusted. Prior to the polymerization in the first-stage polymerization reactor, prepolymerization of propylene monomer may be carried out in order to form polymer chains on the solid catalyst component, which will serve as a foothold for the subsequent main polymerization. The prepolymerization is usually carried out at 40°C or lower, preferably 30°C or lower, and more preferably 20°C or lower.

[0078] As the catalyst, a known olefin polymerization catalyst can be used. Examples of the catalyst used in the first stage to obtain component (A-1a) by polymerizing propylene monomer and, if necessary, a small amount of ethylene monomer include a stereospecific Ziegler-Natta catalyst and a metallocene catalyst.

[0079] As the catalyst used in polymerizing ethylene monomers and propylene monomers in the presence of component (A-1a), a stereospecific Ziegler-Natta catalyst is preferred, and a catalyst containing the following components (A), (B), and (C) (hereinafter also referred to as catalyst (X)) is particularly preferred.

[0080] (a) A solid catalyst containing magnesium, titanium, a halogen, and a phthalate compound as an electron donor compound as essential components. (b) An organoaluminum compound. (c) An organosilicon compound as an external electron donor compound.

[0081] Component (A-1) is preferably obtained by polymerizing ethylene monomer and propylene monomer using catalyst (X) in the presence of component (A-1a). By using catalyst (X), component (A-1) with excellent physical properties can be easily obtained. The molecular weight and stereoregularity distributions of the resulting propylene polymer vary depending on the catalyst used (particularly the electron donor compound of component (A)). These differences affect crystallization behavior, but the details of this relationship have not been clarified. To clarify this, it is necessary to analyze both the molecular weight distribution and stereoregularity distribution as molecular structures. However, the crystallization process is complicated because components with different molecular weights and stereoregularities interact with each other, making it even more difficult to interpret the effects of molecular weight and stereoregularity distribution on crystallization behavior. Furthermore, because actual molding is performed in a flowing state of the molten resin, it is not easy to grasp this phenomenon even with advanced analytical techniques. Therefore, it is virtually impossible to numerically identify the differences in crystallization behavior due to the molecular weight and stereoregularity distributions in polypropylene-based resin compositions obtained using a specific catalyst. The molecular weight distribution and stereoregularity distribution change due to the type of catalyst as described above, as well as thermal deterioration during melt kneading and peroxide treatment.

[0082] Component (A) is prepared using, for example, a titanium compound, a magnesium compound, and an electron donor compound. The titanium compound used in component (A) is a compound represented by the general formula: Ti(OR) ｇ X ４－ｇ (R is a hydrocarbon group, X is a halogen, 0≦g≦4) is preferred. Examples of the hydrocarbon group include methyl, ethyl, propyl, and butyl, and examples of the halogen include Cl and Br.

[0083] More specifically, titanium compounds include TiCl ４ , TiBr ４ , TiI ４ Titanium tetrahalides such as Ti(OCH ３ ) Cl ３ , Ti(OC ２ H ５ ) Cl ３ , Ti(O ｎ -C ４ H ９ ) Cl ３ , Ti(OC ２ H ５ )Br ３ , Ti(O-isoC ４ H ９ )Br ３ Alkoxy titanium trihalides such as Ti(OCH ３ ) ２ Cl ２ , Ti(OC ２ H ５ ) ２ Cl ２ , Ti(O ｎ -C ４ H ９ ) ２ Cl ２ , Ti(OC ２ H ５ ) ２ Br ２ Alkoxy titanium dihalides such as Ti(OCH ３ ) ３ Cl, Ti(OC ２ H ５ ) ３ Cl, Ti(O ｎ -C ４ H ９ ) ３Cl, Ti(OC ２ H ５ ) ３ Monohalogenated trialkoxy titanium compounds such as Br; Ti(OCH ３ ) ４ , Ti(OC ２ H ５ ) ４ , Ti(O ｎ -C ４ H ９ ) ４ These titanium compounds may be used alone or in combination of two or more. Among the titanium compounds, halogen-containing titanium compounds are preferred, titanium tetrahalides are more preferred, and titanium tetrachloride (TiCl) is particularly preferred. ４ )

[0084] Examples of the magnesium compound used in component (A) include magnesium compounds having a magnesium-carbon bond or a magnesium-hydrogen bond, such as dimethylmagnesium, diethylmagnesium, dipropylmagnesium, dibutylmagnesium, diamylmagnesium, dihexylmagnesium, didecylmagnesium, ethylmagnesium chloride, propylmagnesium chloride, butylmagnesium chloride, hexylmagnesium chloride, amylmagnesium chloride, butylethoxymagnesium, ethylbutylmagnesium, butylmagnesium hydride, etc. These magnesium compounds can also be used in the form of a complex compound with, for example, organoaluminum or the like, and may be in either liquid or solid form. Further preferred magnesium compounds include magnesium halides such as magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride; alkoxymagnesium halides such as methoxymagnesium chloride, ethoxymagnesium chloride, isopropoxymagnesium chloride, butoxymagnesium chloride, and octoxymagnesium chloride; allyloxymagnesium halides such as phenoxymagnesium chloride and methylphenoxymagnesium chloride; alkoxymagnesiums such as ethoxymagnesium, isopropoxymagnesium, butoxymagnesium, n-octoxymagnesium, and 2-ethylhexoxymagnesium; dialkoxymagnesiums such as dimethoxymagnesium, diethoxymagnesium, dipropoxymagnesium, dibutoxymagnesium, and ethoxymethoxymagnesium; and allyloxymagnesiums such as ethoxypropoxymagnesium, butoxyethoxymagnesium, phenoxymagnesium, and dimethylphenoxymagnesium. These magnesium compounds may be used alone or in combination of two or more.

[0085] When the electron donor compound used in component (A) is used for the polymerization of component (A-1), it preferably contains a phthalate compound as an essential component. When catalyst (X) containing a phthalate compound as an electron donor is used, M of component (A-1a) ｗ / M ｎGenerally, when an ethylene-α-olefin copolymer is polymerized using a Ziegler-Natta catalyst, components with different ethylene-derived unit contents are produced (so-called composition distribution exists), but it is thought that when catalyst (X) containing a phthalate compound as an electron donor is used, components with a particularly high ethylene-derived unit content, which is effective for impact resistance at low temperatures, compared to the average value of the copolymer, are easily produced.

[0086] Examples of phthalate compounds include monoethyl phthalate, dimethyl phthalate, methyl ethyl phthalate, monoisobutyl phthalate, mono-normal butyl phthalate, diethyl phthalate, ethyl isobutyl phthalate, ethyl-normal butyl phthalate, di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, di-n-heptyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, dineopentyl phthalate, didecyl phthalate, benzyl butyl phthalate, and diphenyl phthalate. Of these, diisobutyl phthalate is particularly preferred.

[0087] Examples of the electron donor compound in the solid catalyst other than the phthalate-based compound include succinate-based compounds and diether-based compounds. The succinate-based compound may be an ester of succinic acid or an ester of a substituted succinic acid having a substituent such as an alkyl group at the 1st or 2nd position of succinic acid. Specific examples include diethyl succinate, dibutyl succinate, diethyl methyl succinate, diethyl diisopropyl succinate, and diallyl ethyl succinate.

[0088] When the electron donor compound used in component (A) is used for the polymerization of component (A-2), it preferably contains a succinate compound as an essential component. When a catalyst (X) containing a succinate compound as an electron donor is used, M of component (A-2a) ｗ / M ｎ A polypropylene resin having a viscosity within the above range can be easily obtained.

[0089] Examples of diether compounds include 2-(2-ethylhexyl)-1,3-dimethoxypropane, 2-isopropyl-1,3-dimethoxypropane, 2-butyl-1,3-dimethoxypropane, 2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-1,3-dimethoxypropane, 2-phenyl-1,3-dimethoxypropane, 2-tert-butyl-1,3-dimethoxypropane, 2-cumyl-1,3-dimethoxypropane, 2-(2-phenylethyl)-1,3-dimethoxypropane, and 2-(2-cyclohexylethyl) -1,3-dimethoxypropane, 2-(p-chlorophenyl)-1,3-dimethoxypropane, 2-(diphenylmethyl)-1,3-dimethoxypropane, 2-(1-naphthyl)-1,3-dimethoxypropane, 2-(p-fluorophenyl)-1,3-dimethoxypropane, 2-(1-decahydronaphthyl)-1,3-dimethoxypropane, 2-(p-tert-butylphenyl)-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-dimethoxypropane, 2,2-dipropyl- 1,3-dimethoxypropane, 2,2-dibutyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-diethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, 2,2-dipropyl-1,3-diethoxypropane, 2,2-dibutyl-1,3-diethoxypropane, 2-methyl-2-ethyl-1,3-dimethoxypropane, 2-methyl-2-propyl-1,3-dimethoxypropane, 2-propyl-2-pentyl-1,3-diethoxypropane, 2-methyl-2-benzyl-1,3-dimethoxypropane, 2-methyl -2-phenyl-1,3-dimethoxypropane, 2-methyl-2-cyclohexyl-1,3-dimethoxypropane, 2-methyl-2-methylcyclohexyl-1,3-dimethoxypropane, 2,2-bis(p-chlorophenyl)-1,3-dimethoxypropane, 2,2-bis(2-phenylethyl)-1,3-dimethoxypropane, 2,2-bis(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-methyl-2-isobutyl-1,3-dimethoxypropane, 2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane, 2,2-bis(2-ethylhexyl)-1,3-dimethoxypropane, 2,2-bis(p-methylphenyl)-1,3-dimethoxypropane, 2-methyl-2-isopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 2,2-dibenzyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-diethoxypropane Examples of 1,3-diethers include 2,2-diisobutyl-1,3-dibutoxypropane, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2,2-di-sec-butyl-1,3-dimethoxypropane, 2,2-di-tert-butyl-1,3-dimethoxypropane, 2,2-dineopentyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2-phenyl-2-benzyl-1,3-dimethoxypropane, and 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane.

[0090] Further specific examples of the 1,3-diether compounds include the following: 1,1-bis(methoxymethyl)-cyclopentadiene; 1,1-bis(methoxymethyl)-2,3,4,5-tetramethylcyclopentadiene; 1,1-bis(methoxymethyl)-2,3,4,5-tetraphenylcyclopentadiene; 1,1-bis(methoxymethyl)-2,3,4,5-tetrafluorocyclopentadiene; 1,1-bis(methoxymethyl)-3,4-dicyclopentylcyclopentadiene; 1,1-bis(methoxymethyl)indene; 1,1-bis(methoxymethyl)-2,3-dimethylindene; 1,1 -Bis(methoxymethyl)-4,5,6,7-tetrahydroindene; 1,1-bis(methoxymethyl)-2,3,6,7-tetrafluoroindene; 1,1-bis(methoxymethyl)-4,7-dimethylindene; 1,1-bis(methoxymethyl)-3,6-dimethylindene; 1,1-bis(methoxymethyl)-4-phenylindene; 1,1-bis(methoxymethyl)-4-phenyl-2-methylindene; 1,1-bis(methoxymethyl)-4-cyclohexylindene; 1,1-bis(methoxymethyl)-7-(3,3, 1,1-bis(methoxymethyl)-7-trimethylsilyl indene; 1,1-bis(methoxymethyl)-7-trifluoromethyl indene; 1,1-bis(methoxymethyl)-4,7-dimethyl-4,5,6,7-tetrahydro indene; 1,1-bis(methoxymethyl)-7-methyl indene; 1,1-bis(methoxymethyl)-7-cyclopentylindene; 1,1-bis(methoxymethyl)-7-isopropyl indene; 1,1-bis(methoxymethyl)-7-cyclohexylindene ; 1,1-bis(methoxymethyl)-7-tert-butylindene; 1,1-bis(methoxymethyl)-7-tert-butyl-2-methylindene; 1,1-bis(methoxymethyl)-7-phenylindene; 1,1-bis(methoxymethyl)-2-phenylindene; 1,1-bis(methoxymethyl)-1H-benzindene; 1,1-bis(methoxymethyl)-1H-2-methylbenzindene; 9,9-bis(methoxymethyl)fluorene; 9,9-bis(methoxymethyl)-2,3,6,7-tetramethylfluorene;9,9-bis(methoxymethyl)-2,3,4,5,6,7-hexafluorofluorene; 9,9-bis(methoxymethyl)-2,3-benzofluorene; 9,9-bis(methoxymethyl)-2,3,6,7-dibenzofluorene; 9,9-bis(methoxymethyl)-2,7-diisopropylfluorene; 9,9-bis(methoxymethyl)-1,8-dichlorofluorene; 9,9-bis(methoxymethyl)-2,7-dicyclopentylfluorene; 9,9-bis(methoxymethyl)-1,8-difluorofluorene; 9,9-bis(methoxymethyl)-1,2,3,4-tetrahydrofluorene; 9,9-bis(methoxymethyl)-1,2,3,4,5,6,7,8-octahydrofluorene; 9,9-bis(methoxymethyl)-4-tert-butylfluorene.

[0091] The electron donor compound used in component (A) preferably contains a diether compound as an essential component, particularly when used to polymerize component (A-3) having a high MFR. By using catalyst (X) containing a diether compound as an electron donor, a polypropylene resin having an MFR of component (A-3) within the above range can be easily obtained.

[0092] Examples of halogen atoms constituting component (a) include fluorine, chlorine, bromine, iodine, and mixtures thereof, with chlorine being particularly preferred.

[0093] Examples of the organoaluminum compound of component (a) include trialkylaluminums such as triethylaluminum and tributylaluminum, trialkenylaluminums such as triisoprenylaluminum, dialkylaluminum alkoxides such as diethylaluminum ethoxide and dibutylaluminum butoxide, alkylaluminum sesquialkoxides such as ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide, R １ ２．５ Al (OR ２ ) ０．５ (R １ , R ２are hydrocarbon groups which may be different or the same. Examples of the alkylaluminum include partially alkoxylated alkylaluminums having an average composition represented by the formula (I), dialkylaluminum halides such as diethylaluminum chloride, dibutylaluminum chloride, and diethylaluminum bromide, alkylaluminum sesquihalides such as ethylaluminum sesquichloride, butylaluminum sesquichloride, and ethylaluminum sesquibromide, partially halogenated alkylaluminums such as alkylaluminum dihalides such as ethylaluminum dichloride, propylaluminum dichloride, and butylaluminum dibromide, partially hydrogenated alkylaluminums such as dialkylaluminum hydrides such as diethylaluminum hydride and dibutylaluminum hydride, and alkylaluminum dihydrides such as ethylaluminum dihydride and propylaluminum dihydride, and partially alkoxylated and halogenated alkylaluminums such as ethylaluminum ethoxychloride, butylaluminum butoxychloride, and ethylaluminum ethoxybromide. One type of the component (A) may be used alone, or two or more types may be used in combination.

[0094] As the external electron donor compound of component (c), an organosilicon compound is used. Preferred organosilicon compounds include, for example, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, t-amylmethyldiethoxysilane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, diphenyldiethoxysilane, bis-o-tolyldimethoxysilane, bis-m-tolyldimethoxysilane, bis-p-tolyldimethoxysilane, and bis-p-tolyldimethoxysilane. Ethoxysilane, bisethylphenyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, phenyltrimethoxysilane, γ-chloropropyltrimethoxysilane, methyltriethoxysilane, biphenyltrimethoxysilane, Nyltriethoxysilane, t-butyltriethoxysilane, thexyltrimethoxysilane, n-butyltriethoxysilane, iso-butyltriethoxysilane, phenyltriethoxysilane, γ-aminopropyltriethoxysilane, chlorotriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, 2-norbornanetrimethoxysilane, 2-norbornanetriethoxysilane, 2-norbornanemethyldimethoxysilane, ketone ethyl acrylate, butyl silicate, trimethylphenoxysilane, methyltriallyloxysilane, vinyltris(β-methoxyethoxysilane), vinyltriacetoxysilane, dimethyltetraethoxydisiloxane, methyl(3,3,3-trifluoro-n-propyl)dimethoxysilane, cyclohexylethyldimethoxysilane, cyclopentyl-t-butoxydimethoxysilane, diisobutyldimethoxysilane, isobutylisopropyldimethoxysilane, n-propyltrimethoxysilane, di-n-propyldimethoxysilane,t-Butylethyldimethoxysilane, t-butylpropyldimethoxysilane, t-butyl-t-butoxydimethoxysilane, isobutyltrimethoxysilane, cyclohexylisobutyldimethoxysilane, di-sec-butyldimethoxysilane, isobutylmethyldimethoxysilane, bis(decahydroisoquinolin-2-yl)dimethoxysilane, diethylaminotriethoxysilane, dicyclopentyl-bis(ethylamino)silane, tetraethoxysilane, tetramethoxysilane, isobutyltriethoxysilane Examples of such silane include tert-butyltrimethoxysilane, i-butyltrimethoxysilane, i-butylsec-butyldimethoxysilane, ethyl(perhydroisoquinolin-2-yl)dimethoxysilane, tri(isopropenyloxy)phenylsilane, i-butyl-i-propyldimethoxysilane, cyclohexyl-i-butyldimethoxysilane, cyclopentyl-i-butyldimethoxysilane, cyclopentylisopropyldimethoxysilane, phenyltriethoxysilane, and p-tolylmethyldimethoxysilane. Among these, ethyltriethoxysilane, n-propyltriethoxysilane, n-propyltrimethoxysilane, t-butyltriethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, t-butylethyldimethoxysilane, t-butylpropyldimethoxysilane, t-butylt-butoxydimethoxysilane, t-butyltrimethoxysilane, i-butyltrimethoxysilane, isobutylmethyldimethoxysilane, i-butylsec-butyldimethoxysilane, ethyl(perhydroisoquinolin-2-yl)dimethoxysilane, bis(decahydroisoquinoline- 2-yl)dimethoxysilane, tri(isopropenyloxy)phenylsilane, thexyltrimethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, vinyltributoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, i-butyl i-propyldimethoxysilane, cyclopentyl t-butoxydimethoxysilane, dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyl i-butyldimethoxysilane, cyclopentyl i-butyldimethoxysilane,Preferred examples of the component (c) include cyclopentylisopropyldimethoxysilane, di-sec-butyldimethoxysilane, diethylaminotriethoxysilane, tetraethoxysilane, tetramethoxysilane, isobutyltriethoxysilane, phenylmethyldimethoxysilane, phenyltriethoxysilane, bis-p-tolyldimethoxysilane, p-tolylmethyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylethyldimethoxysilane, 2-norbornanetriethoxysilane, 2-norbornanemethyldimethoxysilane, diphenyldiethoxysilane, methyl(3,3,3-trifluoro-n-propyl)dimethoxysilane, and ethyl silicate. One type of the component (c) may be used alone, or two or more types may be used in combination.

[0095] The organosilicon compound plays an important role in adjusting the amount of xylene insoluble matter. When other catalyst components are the same, the amount of xylene insoluble matter depends on the type and amount of the organosilicon compound and the polymerization temperature. Even when an appropriate organosilicon compound is used, the amount of the organosilicon compound drops significantly when the amount of the organosilicon compound falls below a certain value, except for diether catalysts. Therefore, when the polymerization temperature is 75°C, the lower limit of the molar ratio of the organosilicon compound to the organoaluminum compound (organosilicon compound / organoaluminum) is preferably 0.015, more preferably 0.018. The upper limit of this ratio is preferably 0.30, more preferably 0.20, and even more preferably 0.10.

[0096] When a phthalate compound is used as the internal electron donor compound, increasing the polymerization temperature increases the amount of xylene-insoluble matter, thereby lowering the lower and upper limits of the preferred molar ratio of the organosilicon compound to the organoaluminum compound (organosilicon compound / organoaluminum). Specifically, when polymerizing at 80°C using a phthalate compound, the lower limit of the molar ratio is preferably 0.010, more preferably 0.015, and even more preferably 0.018. The upper limit of the molar ratio is preferably 0.20, more preferably 0.14, and even more preferably 0.08.

[0097] As the catalyst (X), a catalyst in which component (A) is a trialkylaluminum such as triethylaluminum or triisobutylaluminum, and component (C) is an organosilicon compound such as dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane or diisopropyldimethoxysilane is preferred.

[0098] The method for obtaining the polymerization mixture by multistage polymerization is not limited to the above method, and component (A-1a) may be polymerized in a plurality of polymerization reactors, or component (A-1b) may be polymerized in a plurality of polymerization reactors. Examples of methods for obtaining the polymerization mixture include a method using a polymerization reactor having a gradient in monomer concentration or polymerization conditions. In such a polymerization reactor, for example, one having at least two polymerization zones joined together can be used, and monomers can be polymerized by gas phase polymerization.

[0099] Specifically, in the presence of a catalyst, a monomer is supplied to a polymerization zone consisting of a riser pipe and polymerized, and another monomer is supplied to a downcomer pipe connected to the riser pipe and polymerized, and the polymerization product is recovered while circulating between the riser pipe and the downcomer pipe. This method includes a means for completely or partially preventing the gas mixture present in the riser pipe from entering the downcomer pipe. Furthermore, a gas and / or liquid mixture having a composition different from that of the gas mixture present in the riser pipe is introduced into the downcomer pipe. For example, the method described in JP-A-2002-520426 can be used for this polymerization method.

[0100] The xylene-soluble portion of component (A-1) has an intrinsic viscosity (XSIV) of less than 4 dL / g in tetrahydronaphthalene at 135° C. In order to make the XSIV less than 4 dL / g, the hydrogen concentration in the copolymerization can be adjusted to 0.7 mol% or more.

[0101] [Production method of component (A-2)] The xylene-soluble fraction of component (A-2) has an intrinsic viscosity (XSIV) in tetrahydronaphthalene at 135°C of 4 to 11 dL / g. To achieve an XSIV of 4 to 11 dL / g, the hydrogen concentration in the copolymerization may be adjusted to a range of 1 mol ppm or more and less than 0.7 mol%. Component (A-2) can be obtained in the same manner as in the production method of component (A-1), except that polymerization is performed using an appropriate catalyst system, such as the catalyst (X) containing the above-mentioned succinate compound as an electron donor.

[0102] [Method for producing component (A-3)] Component (A-3) can be produced in the same manner as the first-stage polymerization method in the method for producing component (A-1) described above, except that only propylene monomer is polymerized. The MFR of component (A-3) is 2 to 2000 g / 10 min. In order to achieve an MFR of 2 to 2000 g / 10 min, polymerization can be carried out using an appropriate catalyst system, such as the catalyst (X) containing the above-mentioned diether compound as an electron donor, depending on the target MFR, and the hydrogen concentration conditions can be adjusted appropriately depending on the catalyst system.

[0103] Examples and comparative examples are shown below, but the present invention is not limited to the following examples.

[0104] <<Method for Producing Block Polypropylene>> The components (A-1) and (A-2) used in each example were produced by the following method.

[0105] <Production of Component (A-1)> [Production of Catalyst (X)] MgCl ２ TiCl on top ４ and diisobutyl phthalate as an internal donor were supported on the solid catalyst, which was prepared by the method described in lines 21 to 36 of paragraph 0032 of JP-A No. 2004-27218. Specifically, the method was carried out as follows.

[0106] Under a nitrogen atmosphere, 56.8 g of anhydrous magnesium chloride was completely dissolved in 100 g of absolute ethanol, 500 mL of Vaseline oil "CP15N" manufactured by Idemitsu Kosan Co., Ltd., and 500 mL of silicone oil "KF96" manufactured by Shin-Etsu Silicone Co., Ltd., at 120°C. This solution was stirred at 120°C and 5,000 rpm for 2 minutes using a TK Homomixer manufactured by Tokushu Kika Kogyo Co., Ltd. While maintaining stirring, the solution was poured into 2 L of anhydrous heptane, ensuring that the temperature did not exceed 0°C. The resulting white solid was thoroughly washed with anhydrous heptane, vacuum-dried at room temperature, and further partially deethanolized under a nitrogen stream to obtain MgCl. ２ ・1.2C ２ H ５ 30 g of spherical solid of OH was obtained.

[0107] 30 g of the spherical solid was suspended in 200 mL of anhydrous heptane. While stirring at 0°C, 500 mL of titanium tetrachloride was added dropwise over 1 hour. Next, heating was initiated, and once the temperature reached 40°C, 4.96 g of diisobutyl phthalate was added, and the mixture was heated to 100°C over approximately 1 hour. After reacting at 100°C for 2 hours, the solid was collected by hot filtration. 500 mL of titanium tetrachloride was then added to the reaction mixture, stirred, and then reacted at 120°C for 1 hour. After the reaction was completed, the solid was collected again by hot filtration and washed seven times with 1.0 L of hexane at 60°C and three times with 1.0 L of hexane at room temperature to obtain a solid catalyst. The titanium content of the resulting solid catalyst component was measured and found to be 2.36% by mass.

[0108] Next, the solid catalyst was contacted with triethylaluminum (TEAL) as an organoaluminum compound and dicyclopentyldimethoxysilane (DCPMS) as an external electron donor compound at 12°C for 24 minutes in amounts such that the mass ratio of TEAL to the solid catalyst was 20 and the mass ratio of TEAL / DCPMS was 10 (equivalent to the molar ratio of organosilicon compound / organoaluminum described above of 0.05), thereby obtaining catalyst (X).

[0109] [Production of Component (A-1-1)] The catalyst (X) obtained above was prepolymerized by maintaining it in a suspended state in liquid propylene at 20°C for 5 minutes. The obtained prepolymer was introduced into the first-stage polymerization reactor of a polymerization apparatus equipped with two-stage polymerization reactors connected in series, and propylene was supplied to produce a propylene homopolymer. Subsequently, propylene homopolymer, propylene, and ethylene were supplied to the second-stage polymerization reactor to produce an ethylene-propylene copolymer. During the polymerization, the temperature and pressure were adjusted, and hydrogen was used as a molecular weight modifier.

[0110] The ethylene-derived unit content in the rubber phase was adjusted by changing the ratio of ethylene to the total of ethylene and propylene in the second reactor. The XSIV was adjusted by changing the hydrogen concentration in the second reactor. The MFR was adjusted by changing the hydrogen concentration in the first reactor.

[0111] The polymerization temperature and the ratio of reactants in the first-stage reactor were 80°C and 1.049 mol% for the polymerization temperature and hydrogen concentration, respectively, and in the second-stage reactor were 80°C, 3.167 mol%, and 0.456 mol% for the polymerization temperature, hydrogen concentration, and ratio of ethylene to the total of ethylene and propylene, respectively. The polymerization times in the first and second stages were adjusted so that the ratio of ethylene-propylene copolymer (rubber phase) was 26% by mass. By the above method, the target component (A-1-1) was obtained.

[0112] The resulting component (A-1-1) is a polymerization mixture of component (A-1a), a propylene polymer constituting the continuous phase, and component (A-1b), an ethylene-propylene copolymer constituting the rubber phase, and is the aforementioned component (A-1). For component (A-1-1), the total ethylene content of the block polypropylene, the ethylene-derived unit content in the continuous phase, the ethylene-derived unit content in the rubber phase, XSIV (intrinsic viscosity of the xylene-soluble fraction in tetrahydronaphthalene at 135°C), and MFR (230°C, 2.16 kg) were measured using the methods described below, and the results are shown in Table 1.

[0113] [Production of Component (A-1-2)] Component (A-1-2) was produced in the same manner as in the case of Component (A-1-1), except that the hydrogen concentration in the first-stage reactor, the hydrogen concentration in the second-stage reactor, the ratio of ethylene to the total of ethylene and propylene, and the first-stage and second-stage polymerization times were adjusted so that the total ethylene amount of the block polypropylene, the ethylene-derived unit content in the continuous phase, the ethylene-derived unit content in the rubber phase, the proportion of the rubber phase, XSIV, and MFR were as shown in Table 1.

[0114] <Preparation of Component (A-2)> [Preparation of Catalyst (X)] A solid catalyst component was prepared according to the preparation method described in the examples of JP 2011-500907 A. Specifically, the solid catalyst component was prepared as follows: In a 500 mL four-neck round-bottom flask purged with nitrogen, 250 mL of TiCl ４ was introduced at 0° C. While stirring, 10.0 g of finely divided MgCl ２ ・1.8C ２ H ５ OH, and 9.1 mmol of diethyl-2,3-(diisopropyl)succinate were added. ２ ・1.8C ２ H ５ OH was prepared according to the method described in Example 2 of U.S. Pat. No. 4,399,054, except that the rotation speed was 3,000 rpm instead of 10,000 rpm. The temperature of the contents was raised to 100°C and held for 120 minutes. Stirring was then stopped, the solid product was allowed to settle, and the supernatant liquid was siphoned off. The following procedure was then repeated twice: 250 mL of fresh TiCl was added. ４ The mixture was reacted at 120°C for 60 minutes, and the supernatant was siphoned off. The solid was washed six times with anhydrous hexane (6 x 100 mL) at 60°C.

[0115] The solid catalyst was contacted with triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) at room temperature for 5 minutes in amounts such that the weight ratio of TEAL to the solid catalyst was 18 and the weight ratio of TEAL / DCPMS was 10, to obtain catalyst (X).

[0116] [Production of Component (A-2-1)] The catalyst (X) obtained above was suspended in liquid propylene and maintained at 20°C for 5 minutes to carry out prepolymerization. Using the resulting prepolymer, (A-2-1) in Table 1 was produced in the same manner as for (A-1-1). In the first-stage reactor, the polymerization temperature and hydrogen concentration were 80°C and 0.829 mol%, respectively. In the second-stage reactor, the polymerization temperature, hydrogen concentration, and proportion of ethylene to the total of ethylene and propylene were 80°C, 0.008 mol%, and 0.245 mol ratio, respectively. The residence polymerization time distributions in the first and second stages were adjusted so that the proportion of ethylene-propylene copolymer (rubber phase) was 30% by mass.

[0117] [Production of Component (A-2-2)] Component (A-2-2) was produced in the same manner as in the production of Component (A-2-1), except that the hydrogen concentration in the first-stage reactor, the hydrogen concentration in the second-stage reactor, the ratio of ethylene to the total of ethylene and propylene, and the first-stage and second-stage polymerization times were adjusted so that the total ethylene amount of the block polypropylene, the ethylene-derived unit content in the continuous phase, the ethylene-derived unit content in the rubber phase, the proportion of the rubber phase, XSIV, and MFR were as shown in Table 1.

[0118] Other Polymers The following commercially available products were used as components (A-3), (B-1) and (B-2) in the examples.

[0119] Component (A-3-1): PWH00N, propylene homopolymer, manufactured by SunAllomer Co., Ltd. Component (A-3-2): PMB02A, propylene homopolymer, manufactured by SunAllomer Co., Ltd. Component (A-3-3): PM900A, propylene homopolymer, manufactured by SunAllomer Co., Ltd.

[0120] Component (B-1-1): Engage (registered trademark) XLT8677, manufactured by The Dow Chemical Company, a copolymer of ethylene and 1-octene, with a density of 0.870 g / cm ３ Component (B-1-2): Engage 8842, manufactured by The Dow Chemical Company, a copolymer of ethylene and 1-octene, with a density of 0.857 g / cm ３ Component (B-2-1): Engage 7467, manufactured by The Dow Chemical Company, a copolymer of ethylene and 1-butene, with a density of 0.862 g / cm ３ .

[0121]

[0122] <<Measurement Method>> The measured values ​​in Table 1 were determined by the following methods.

[0123] <Total Ethylene Content of Block Polypropylene> Component (A-1) or component (A-2), which is a block polypropylene, was dissolved as a sample in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene. The dissolved sample was analyzed using an AVANCE III HD400 (manufactured by Bruker). １３ C resonance frequency 100 MHz) under the conditions of measurement temperature 120 °C, flip angle 45 degrees, pulse interval 7 seconds, sample rotation speed 20 Hz, and cumulative number 5000. １３ Using the obtained C-NMR spectrum, the total ethylene content (mass%) of component (A-1) and component (A-2) was determined by the method described in Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 15, 1150-1152 (1982).

[0124] <Content of Ethylene-Derived Units in Continuous Phase> The content of ethylene-derived units was determined in the same manner as for the total ethylene amount of block polypropylene, except that component (A-1a) or component (A-2a), which is the continuous phase, was used as the sample. The total ethylene amount (% by mass) in the method for measuring the total ethylene amount of block polypropylene corresponds to the content of ethylene-derived units (% by mass) in the continuous phase. The sample was taken from the first-stage polymerization reactor before the rubber phase was polymerized.

[0125] <Content of Ethylene-Derived Units in Rubber Phase> When the content of ethylene-derived units in the continuous phase was zero, the spectrum obtained above was used to calculate the content of ethylene-derived units (mass%) in the rubber phase in the same manner as for the total ethylene amount of block polypropylene, except that the integrated intensity T'ββ calculated by the following formula was used instead of the integrated intensity of Tββ calculated when measuring the total ethylene amount of block polypropylene by the method described in the above document: T'ββ=0.98×Sαγ×A / (1−0.98×A), where A=Sαγ / (Sαγ+Sαδ), and is calculated from Sαγ and Sαδ described in the above document.

[0126] <Proportion of Rubber Phase in Block Polypropylene> When the ethylene-derived unit content in the continuous phase is zero, the proportion of component (A-1b) in component (A-1) or the proportion of component (A-2b) in component (A-2) can be calculated by the following formula: Component (A-1b) / Component (A-1) (unit: mass %)=Total ethylene amount in component (A-1) / (Ethylene-derived unit content in component (A-1b) / 100) Component (A-2b) / Component (A-2) (unit: mass %)=Total ethylene amount in component (A-2) / (Ethylene-derived unit content in component (A-2b) / 100

[0127] <XSIV of Block Polypropylene> 2.5 g of the block polypropylene component (A-1) or component (A-2) was used as a sample. The sample was placed in a flask containing 250 mL of o-xylene (solvent). Using a hot plate and a reflux condenser, the mixture was stirred for 30 minutes at 135°C while purging with nitrogen, until complete dissolution was achieved. The mixture was then cooled to 25°C for 1 hour. The resulting solution was filtered using filter paper. After filtration, 100 mL of the filtrate was collected and transferred to an aluminum cup or the like. The filtrate was evaporated to dryness at 140°C while purging with nitrogen, and allowed to stand at room temperature for 30 minutes to obtain a xylene-soluble fraction. The intrinsic viscosity (XSIV) was measured in tetrahydronaphthalene at 135°C using an automatic capillary viscosity measuring device (SS-780-H1, manufactured by Shibayama Scientific Instruments Manufacturing Co., Ltd.).

[0128] <MFR> As described below, MFR was measured in accordance with JIS K7210-1 and JIS K6921-2 at a temperature of 230°C and a load of 2.16 kg. For powder materials (A-1-2 and A-3-1), 0.05 g of H-BHT manufactured by Honshu Chemical Industry Co., Ltd. was added to 5 g of the sample, and the mixture was homogenized by dry blending before measurement.

[0129] Examples and Comparative Examples: Components (A-1), (A-2), (A-3), (B-1), (B-2), (C), and (D) were blended in the formulations shown in Tables 2 and 3 with 0.1 parts by mass of BASF B225 (an antioxidant) and 0.3 parts by mass of ADEKA Adekastab LA502XP (a weathering agent) (total: 0.4 parts by mass), as shown in Tables 2 and 3, and the blend was stirred and mixed for 1 minute using a Henschel mixer. The mixture was melt-kneaded and extruded at a cylinder temperature of 200°C using a co-rotating twin-screw extruder TEX-30α manufactured by JSW Corporation. The strands were cooled in water and then cut using a pelletizer to obtain pellets of a polypropylene resin composition.

[0130] The following commercially available products were used as components (C) and (D) in Tables 2 and 3. Talc: HTP05L manufactured by Imifabi, volume average particle size 5 μm. MgSt: magnesium stearate manufactured by NOF Corporation. CaSt: calcium stearate manufactured by NOF Corporation.

[0131] The MFR of the obtained polypropylene resin composition, and the flexural modulus, Izod impact strength, and shrinkage of the injection-molded article were measured or evaluated by the following methods. The measurement and evaluation results are shown in Tables 2 and 3.

[0132] <MFR Fully Automatic> Measurement was carried out in accordance with JIS K6921-2 under conditions of a temperature of 230°C and a load of 2.16 kg.

[0133] <Density> Measured in accordance with JIS K 7112.

[0134] <Flexural Modulus> Using an injection molding machine (Fanuc 2000i, manufactured by Fanuc Corporation), test specimens for measurement, each having a width of 10.0 mm, a thickness of 4.0 mm, and a length of 80 mm, were molded under the following conditions: cylinder temperature of 200°C, mold temperature of 40°C, average injection speed of 200 mm / sec, and cooling time of 20 seconds. Using the test specimens for measurement, the flexural modulus was measured in accordance with JIS K6921-2 under the conditions of a temperature of 23°C, a span of 64 mm, and a bending speed of 2.0 mm / min. The higher the flexural modulus value, the more excellent the rigidity.

[0135] <Izod impact strength> Using the same test pieces as those used to measure the flexural modulus, the Izod impact strength was measured in accordance with JIS K6921-2 under the temperature conditions of 23° C. and −20° C. The higher the Izod impact strength value, the more excellent the impact resistance.

[0136] <Shrinkage Rate> A flat plate was injection molded into a mold having a thickness of 3 mm, a width of 140 mm, and a length of 300 mm under constant molding conditions and filling rate. The differences between the actual dimensions of the plate and the cavity dimensions were determined in the machine direction (MD) and the transverse direction (TD), and the ratios to the respective actual dimensions were expressed as percentages. The average values ​​in the MD and TD were taken as the shrinkage rate of the composition.

[0137]

[0138]

[0139] As shown in Tables 2 and 3, the polypropylene resin compositions of Examples 1 to 8, which contained a polypropylene resin (A) containing block polypropylene (A-1), an ethylene-α-olefin polymer (B) which is a polymer of ethylene and an α-olefin having 4 to 10 carbon atoms, and an inorganic filler (C), as well as a specific range of amounts of stearate (D), maintained a high flexural modulus (rigidity) while also exhibiting high Izod impact strength (impact resistance) at 23°C and -20°C, providing an excellent balance (physical property balance) between rigidity and impact resistance (at room temperature and low temperatures). The polypropylene resin composition of Comparative Example 1, which did not contain stearate (D), had low Izod impact strength at room temperature and also low MFR (fluidity). Of the polypropylene resin compositions of Comparative Examples 2 to 5, which contained a low amount of stearate (D), the compositions of Comparative Examples 2 and 3 had low Izod impact strength at room temperature, and the compositions of Comparative Examples 4 and 5 had low flexural modulus relative to their Izod impact strength.

Claims

1. A polypropylene resin composition comprising: a polypropylene resin (A) containing a block polypropylene (A-1) composed of a continuous phase made of a propylene polymer (A-1a) and a rubber phase made of an ethylene-propylene copolymer (A-1b); an ethylene-α-olefin polymer (B) which is a polymer of ethylene and an α-olefin having 4 to 10 carbon atoms; an inorganic filler (C); and a stearate (D), wherein the block polypropylene (A-1) has a xylene-soluble portion having an intrinsic viscosity of less than 4 dl / g in tetrahydronaphthalene at 135°C; a content of the polypropylene-based resin (A) of 20 to 80 parts by mass, a content of the ethylene-α-olefin polymer (B) of 10 to 40 parts by mass, a content of the inorganic filler (C) of 10 to 40 parts by mass, and a content of the stearate (D) of 0.17 to 2.0 parts by mass, relative to a total of 100 parts by mass of the polypropylene-based resin (A), the ethylene-α-olefin polymer (B), and the inorganic filler (C); and a total content of the polypropylene-based resin (A), the ethylene-α-olefin polymer (B), and the inorganic filler (C) of 90% by mass or more relative to the total mass of the polypropylene-based resin composition.

2. The polypropylene resin composition according to claim 1, wherein the polypropylene resin (A) further comprises a block polypropylene (A-2) composed of a continuous phase made of a propylene polymer (A-2a) and a rubber phase made of an ethylene-propylene copolymer (A-2b), and the xylene-soluble portion of the block polypropylene (A-2) has an intrinsic viscosity of 4 to 11 dl / g in tetrahydronaphthalene at 135°C.

3. The polypropylene resin composition according to claim 1 or 2, wherein the polypropylene resin (A) further contains a propylene homopolymer (A-3), and the propylene homopolymer (A-3) has a melt flow rate of 2 to 2,000 g / 10 min measured under conditions of a temperature of 230°C and a load of 2.16 kg.

4. The polypropylene-based resin composition according to claim 1 or 2, wherein the ethylene-α-olefin polymer (B) comprises an ethylene-α-olefin polymer (B-1) consisting of ethylene and an α-olefin having 8 to 10 carbon atoms, and optionally an ethylene-α-olefin polymer (B-2) consisting of ethylene and an α-olefin having 4 to 7 carbon atoms, and the content of the ethylene-α-olefin polymer (B-1) is 3 to 40 parts by mass and the content of the ethylene-α-olefin polymer (B-2) is 0 to 20 parts by mass per 100 parts by mass of the total of the polypropylene-based resin (A), the ethylene-α-olefin polymer (B), and the inorganic filler (C).

5. The polypropylene-based resin composition according to claim 1 or 2, wherein the stearate (D) comprises magnesium stearate and calcium stearate, and the content of the magnesium stearate is 0.10 to 1.0 part by mass and the content of the calcium stearate is 0.07 to 1.0 part by mass relative to a total of 100 parts by mass of the polypropylene-based resin (A), the ethylene-α-olefin polymer (B), and the inorganic filler (C).

6. The polypropylene resin composition according to claim 1 or 2, which has a melt flow rate of 35 g / 10 min or more measured at a temperature of 230° C. under a load of 2.16 kg.

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