Polymer components based on polypropylene and injection-molded products made from it.

Abstract

Provided are: a propylene polymer composition which has good thermal stability, and, when being molded, provides a molded article having good external appearance; and an injection-molded article comprising the propylene polymer composition and having good external appearance. The propylene polymer composition according to the present invention contains: a propylene polymer (A) which is one or more propylene polymers selected from the group consisting of a propylene homopolymer (A-1) and a heterophasic propylene polymer (A-2); and carbon black (D), wherein the contained amount of the carbon black (D) is 0.001-1.7 parts by weight with respect to a total of 100 parts by weight of the propylene polymer (A), the carbon black (D) has a primary particle size of 15-39 nm, and x defined in formula (1) is 1-430. The composition according to the present invention can further contain an ethylene -α- olefin copolymer (B). x = a × S (1) (in the formula, a represents the concentration of oxygen forming a double bond with carbon on the surface of the carbon black (unit: atom%), and S represents the nitrogen adsorption specific surface area of the carbon black (unit: m2 / g))

Description

Propylene-based polymer composition and injection molded article made therefrom The present invention relates to a propylene-based polymer composition and an injection molded article made therefrom. Propylene-based polymers are used in home appliance parts, automotive parts, etc. because they are excellent in rigidity, impact strength, etc. Propylene-based polymers used in products that require a high-class feeling and designability are usually colored by blending pigments. When coloring black, carbon black is often used as the pigment. In the injection molded article of the composition containing a propylene-based polymer and carbon black, streak-like color unevenness may occur, and the following composition is known for the purpose of improving this defect. Patent Document 1 describes a composition containing a polypropylene-based resin as a main component, talc, an ethylene-butene copolymer elastomer, a modified polypropylene, an erucic acid amide, and carbon black. JP 2013-209472 A However, the above composition does not have sufficient thermal stability. Under such circumstances, an object of the present invention is to provide a propylene-based polymer composition that has good thermal stability and gives a molded article with good appearance when molded, and an injection molded article made therefrom with good appearance. The present invention, in a first aspect, A propylene-based polymer composition containing a propylene-based polymer (A), which is one or more propylene-based polymers selected from the group consisting of a propylene homopolymer (A-1) and a heterophasic propylene-based polymer (A-2), and carbon black (D), With the total weight of the propylene-based polymer (A) being 100 parts by weight, The content of carbon black (D) is 0.001 part by weight or more and 1.7 parts by weight or less, The above carbon black (D) has a primary particle size of 15 nm or more and 39 nm or less, and relates to a propylene-based polymer composition in which x defined by the following formula (1) is 1 or more and 430 or less. x = a × S (1) (In the formula, a is the concentration (unit: atom%) of oxygen that is double-bonded to carbon on the carbon black surface, and S is the nitrogen adsorption specific surface area of the carbon black (unit: m ２ / g).) In one embodiment, the nitrogen adsorption specific surface area of the carbon black (D) is 60 m ２ / g or more and 360 m ２ / g or less, and the volatile component content is 1.1% by weight or more and 10% by weight or less. In one embodiment, the propylene-based polymer (A) includes a propylene homopolymer (A-1) and a heterophasic propylene-based polymer (A-2), and the heterophasic propylene-based polymer (A-2) includes a propylene homopolymer component (A-2-1) and a propylene-ethylene copolymer component (A-2-2) having an intrinsic viscosity of 2.0 dl / g or more and 10.0 dl / g or less. In one embodiment, the propylene-based polymer composition further contains an ethylene-α-olefin copolymer (B) selected from the group consisting of an ethylene-α-olefin copolymer (B-1) having monomer units derived from ethylene and monomer units derived from an α-olefin having 4 or more carbon atoms and an ethylene-propylene copolymer (B-2), With the total weight of the propylene-based polymer (A) and the ethylene-α-olefin copolymer (B) being 100 parts by weight, The content of the propylene-based polymer (A) is 86 parts by weight or more and 99 parts by weight or less, The content of the ethylene-α-olefin copolymer (B) is 1 part by weight or more and 14 parts by weight or less, The content of the carbon black (D) is 0.001 part by weight or more and 1.5 parts by weight or less, The content of the monomer units derived from ethylene contained in the ethylene-α-olefin copolymer (B-1) is 40% by weight or more and 99% by weight or less (provided that the total weight of the ethylene-α-olefin copolymer (B-1) is 100% by weight), The ethylene-propylene copolymer (B-2) has an intrinsic viscosity of 0.1 dl / g or more and less than 2.0 dl / g. In a second aspect, the present invention relates to an injection molded article made of the propylene-based polymer composition. According to the present invention, it is possible to obtain a propylene-based polymer composition that has good thermal stability and gives a molded article having good appearance when molded, and an injection molded article made thereof having good appearance. As described above, in a first aspect, the present invention relates to a propylene-based polymer composition containing a propylene-based polymer (A), which is at least one propylene-based polymer selected from the group consisting of a propylene homopolymer (A-1) and a heterophasic propylene-based polymer (A-2), and carbon black (D). The above propylene-based polymer (A) is at least one propylene-based polymer selected from the group consisting of a propylene homopolymer (A-1) and a heterophasic propylene-based polymer (A-2). From the viewpoints of rigidity and impact resistance, the propylene-based polymer (A) is preferably a heterophasic propylene-based polymer (A-2) or a mixture of a heterophasic propylene-based polymer (A-2) and a propylene homopolymer (A-1). The above heterophasic propylene-based polymer (A-2) is a copolymer obtained by multi-stage polymerization and composed of a propylene homopolymer component (A-2-1) and a propylene-ethylene copolymer component (A-2-2). The propylene-ethylene copolymer component (A-2-2) is usually a propylene-ethylene random copolymer. From the viewpoints of rigidity, impact resistance, and moldability, the molecular weight distribution of the propylene homopolymer component (A-2-1) is preferably from 3 to 10, more preferably from 3.0 to 10.0, and still more preferably from 3.5 to 9.0. The molecular weight distribution is defined as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), i.e., Mw / Mn, and the number average molecular weight and the weight average molecular weight are measured by gel permeation chromatography (hereinafter referred to as GPC). From the viewpoint of rigidity, １３The isotactic pentad fraction of the propylene homopolymer component (A-2-1) measured by 13C-NMR is preferably 0.95 or more, more preferably 0.97 or more. The isotactic pentad fraction is measured by the method described in Macromolecules, Vol. 6, p. 925 (1973). The isotactic pentad fraction refers to the isotactic fraction in consecutive pentad units in the propylene polymer chain. １３ In the measurement by 13C-NMR spectrum, １３ among the total absorption peaks in the methyl carbon region of the 13C-NMR spectrum, the intensity fraction of the mmmm peak is taken as the isotactic pentad fraction. The peak assignment in the NMR spectrum is carried out based on the description in Macromolecules, Vol. 8, p. 687 (1975). From the viewpoint of moldability, the intrinsic viscosity (hereinafter sometimes referred to as [η]) of the propylene homopolymer component (A-2-1) measured in a tetralin solution at a temperature of 135 °C Ｐ is preferably 0.7 to 1.5 dl / g, more preferably 0.8 to 1.3 dl / g. From the viewpoints of moldability and appearance, the intrinsic viscosity (hereinafter sometimes referred to as [η]) of the propylene-ethylene copolymer component (A-2-2) measured in a tetralin solution at a temperature of 135 °C ＥＰ is preferably 2.0 dl / g or more and 10.0 dl / g or less, more preferably 2.1 dl / g or more and 8.0 dl / g or less, still more preferably 2.5 dl / g or more and 7.5 dl / g or less. From the viewpoint of impact resistance, the content [(C2') ＥＰ of the monomer unit derived from ethylene contained in the propylene-ethylene copolymer component (A-2-2) is preferably 21 to 99% by weight, more preferably 23 to 55% by weight, still more preferably 25 to 45% by weight (where the total weight of the propylene-ethylene copolymer component (A-2-2) is taken as 100% by weight). From the viewpoint of formability, the content of the propylene-ethylene copolymer component (A-2-2) contained in the heterophasic propylene-based polymer (A-2) is preferably 8 to 35% by weight (however, assuming the total weight of the heterophasic propylene-based polymer (A-2) is 100% by weight). From the viewpoints of rigidity, impact resistance, and formability, the molecular weight distribution of the propylene homopolymer (A-1) is preferably 3 to 10, more preferably 3.5 to 9.0. The definition and measurement method of the molecular weight distribution are the same as described above. From the viewpoint of rigidity, １３ The isotactic pentad fraction of the propylene homopolymer (A-1) measured by C-NMR is preferably 0.95 or more, more preferably 0.97 or more. The definition and determination method of the isotactic pentad fraction are the same as described above. From the viewpoint of formability, the intrinsic viscosity of the propylene homopolymer (A-1) measured in a tetralin solution at 135 °C (hereinafter sometimes referred to as [η]) is preferably 0.7 to 1.5 dl / g, more preferably 0.8 to 1.3 dl / g. The propylene-based polymer (A) can be produced by a method of polymerizing a monomer using a stereoregular olefin polymerization catalyst. As the catalyst, a known stereoregular olefin polymerization catalyst can be used, for example, a Ziegler-Natta catalyst system, a metallocene catalyst system, a catalyst system combining them, etc. Examples of the polymerization method include a bulk polymerization method, a solution polymerization method, a slurry polymerization method, a gas phase polymerization method, or a polymerization method combining these polymerization methods arbitrarily. Preferably, it is a continuous gas phase polymerization method. The polymerization conditions such as the polymerization temperature, polymerization pressure, monomer concentration, catalyst input amount, and polymerization time can be appropriately determined according to the composition and structure of the target propylene-based polymer (A). The method for producing the heterophagic propylene-based polymer (A-2) preferably comprises a first step of homopolymerizing propylene in the presence of a stereoregular olefin polymerization catalyst to obtain a propylene homopolymer component (A-2-1), and a second step of copolymerizing ethylene and propylene in the presence of the propylene homopolymer component (A-2-1) subsequent to the first step to obtain a propylene-ethylene copolymer component (A-2-2). This multistage polymerization is also referred to as a polymerization polymer blend. In one embodiment, the propylene-based polymer composition of the present invention contains an ethylene-α-olefin copolymer (B) in addition to the propylene-based polymer (A). The ethylene-α-olefin copolymer (B) is one or more ethylene-α-olefin copolymers selected from the group consisting of an ethylene-α-olefin copolymer (B-1) having monomer units derived from ethylene and monomer units derived from an α-olefin having 4 or more carbon atoms, and an ethylene-propylene copolymer (B-2). Examples of the α-olefin having 4 or more carbon atoms in the ethylene-α-olefin copolymer (B-1) include butene-1, pentene-1, hexene-1, heptene-1, octene-1, and decene, and preferably, α-olefins having 4 or more and 8 or less carbon atoms such as butene-1, hexene-1, and octene-1. The α-olefin constituting the ethylene-α-olefin copolymer (B-1) may be one kind or two or more kinds. The ethylene-α-olefin copolymer (B-1) is preferably a random copolymer. Examples of the ethylene-α-olefin copolymer (B-1) include an ethylene-butene-1 copolymer, an ethylene-hexene-1 copolymer, and an ethylene-octene-1 copolymer, and preferably, an ethylene-octene-1 copolymer and an ethylene-butene-1 copolymer. The composition of the present invention may contain two or more of the ethylene-α-olefin copolymers (B-1). The content of the monomer unit derived from ethylene contained in the ethylene-α-olefin copolymer (B-1) is 40 to 99% by weight, preferably 50 to 90% by weight (however, the total weight of the ethylene-α-olefin copolymer (B-1) is taken as 100% by weight). The molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer (B-1) is preferably 2.7 or less. Also, the melt flow rate of the ethylene-α-olefin copolymer (B-1) (hereinafter sometimes abbreviated as MFR; measured according to JIS K6758 at a temperature of 190°C and a load of 2.16 kgf) is preferably 0.1 to 15 g / 10 min. From the viewpoint of mechanical properties, the molecular weight distribution of the ethylene-octene-1 copolymer used as the ethylene-α-olefin copolymer (B-1) is preferably 2.5 or less, more preferably 2.3 or less. From the viewpoint of impact resistance, the content of the monomer unit derived from octene-1 contained in the ethylene-octene-1 copolymer is preferably 15 to 45% by weight, more preferably 18 to 42% by weight (however, the total weight of the ethylene-octene-1 copolymer is taken as 100% by weight). From the viewpoints of moldability and impact resistance, the MFR of the ethylene-octene-1 copolymer (measured according to JIS K6758 at a temperature of 190°C and a load of 2.16 kgf) is preferably 0.5 to 15 g / 10 min, more preferably 1 to 13 g / 10 min. From the viewpoint of mechanical properties, the molecular weight distribution of the ethylene-butene-1 copolymer is preferably 2.7 or less, more preferably 2.5 or less. From the viewpoint of impact resistance, the content of the monomer unit derived from butene-1 contained in the ethylene-butene-1 copolymer is preferably 15 to 35% by weight, more preferably 17 to 33% by weight (however, the total weight of the ethylene-butene-1 copolymer is taken as 100% by weight). From the viewpoints of impact resistance and moldability, the MFR of the ethylene-butene-1 copolymer (measured at 190°C and a load of 2.16 kgf according to JIS K6758) is preferably 0.5 to 15 g / 10 min, more preferably 1 to 13 g / 10 min. From the viewpoint of mechanical properties, the molecular weight distribution of the ethylene-propylene copolymer (B-2) is preferably 2.7 or less, more preferably 2.5 or less. From the viewpoint of impact resistance, the content of the monomer unit derived from ethylene contained in the ethylene-propylene copolymer (B-2) is preferably 1 to 20% by weight, more preferably 2 to 20% by weight, and still more preferably 4 to 19% by weight (however, the total weight of the ethylene-propylene copolymer is taken as 100% by weight). Further, the intrinsic viscosity of the ethylene-propylene copolymer (B-2) is 0.1 dl / g or more and less than 2.0 dl / g, preferably 1.0 dl / g or more, preferably 1.9 dl / g or less, more preferably 1.8 dl / g or less, and still more preferably 1.5 dl / g or less. The above intrinsic viscosity is measured in a tetralin solution at a temperature of 135°C. From the viewpoints of impact resistance and moldability, the MFR of the ethylene-propylene copolymer (B-2) (measured according to JIS K6758 at a temperature of 190°C and a load of 2.16 kgf) is preferably 0.1 to 15 g / 10 min, more preferably 1.0 to 13 g / 10 min. Examples of the method for producing the ethylene-α-olefin copolymer (B) include a method of copolymerizing ethylene and at least one α-olefin using an olefin polymerization catalyst. As the catalyst, a known olefin polymerization catalyst can be used, and examples thereof include a catalyst system composed of a vanadium compound and an organoaluminum compound, a Ziegler-Natta catalyst system, and a metallocene catalyst system. Examples of the polymerization method include a solution polymerization method, a slurry polymerization method, a high-pressure ionic polymerization method, and a gas-phase polymerization method. When the composition of the present invention contains a propylene-based polymer (A) and an ethylene-α-olefin copolymer (B), from the viewpoint of the balance between rigidity and impact resistance, the content of the ethylene-α-olefin copolymer (B) contained in the composition of the present invention is 1 to 14 parts by weight, preferably 3 to 13 parts by weight, and more preferably 5 to 13 parts by weight, based on 100 parts by weight of the total weight of the propylene-based polymer (A) and the ethylene-α-olefin copolymer (B). The composition of the present invention may contain an inorganic filler (C). As the inorganic filler (C), those capable of improving rigidity are preferable, and examples thereof include calcium carbonate, barium sulfate, mica, crystalline calcium silicate, talc, magnesium sulfate fiber, and mixtures thereof. Preferably, it is talc, magnesium sulfate fiber, or a mixture thereof. From the viewpoints of rigidity and heat resistance, talc is preferably a pulverized product of magnesium hydrosilicate. The crystal structure of talc is a pyrophyllite-type three-layer structure, and talc is a stack of this structure. In particular, flat plate-like talc pulverized to about the unit layer of crystals is preferable. From the viewpoint of mechanical properties such as rigidity and impact resistance, the average particle size of talc is preferably 3 μm or less. Here, the average particle size of talc means the 50% equivalent particle size D obtained from the integral distribution curve measured by the undersize method by suspending talc in a dispersion medium (water or alcohol) using a centrifugal sedimentation type particle size distribution measuring device. ５０ is meant. In order to improve the interfacial adhesion with the propylene-based polymer (A) or improve the dispersibility, the surface of talc may be treated with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a higher fatty acid ester, a higher fatty acid amide, a higher fatty acid salt, or a surfactant. From the viewpoint of mechanical properties such as rigidity and impact resistance, the average fiber length of magnesium sulfate fiber is preferably 5 to 50 μm, more preferably 10 to 30 μm. From the viewpoint of mechanical properties such as rigidity and impact resistance, the average fiber diameter of magnesium sulfate fiber is preferably 0.3 to 2 μm, more preferably 0.5 to 1 μm. From the viewpoint of rigidity, the content of the inorganic filler (C) contained in the composition of the present invention is preferably 3 parts by weight or more, more preferably 6 parts by weight or more, and still more preferably 19 parts by weight or more (however, the total weight of the propylene-based polymer (A) is 100 parts by weight). From the viewpoints of impact strength and appearance, the content of the inorganic filler (C) contained in the composition is preferably 44 parts by weight or less. Further, when the composition of the present invention contains an ethylene-α-olefin copolymer (B), the content of the inorganic filler (C) contained in the composition is preferably 3 parts by weight or more, more preferably 6 parts by weight or more, and still more preferably 19 parts by weight or more (however, the total weight of the propylene-based polymer (A) and the ethylene-α-olefin copolymer (B) is 100 parts by weight). From the viewpoints of impact strength and appearance, the content of the inorganic filler (C) contained in the composition is preferably 38 parts by weight or less. The pH of the carbon black (D) is preferably 2 to 8. The pH of the carbon black is measured according to the method described in JIS K6221-1982. As the carbon black (D), commercially available carbon black can be appropriately selected and used. The primary particle diameter of the carbon black (D) is 15 nm or more and 39 nm or less, preferably 16 nm or more and 25 nm or less, and more preferably 16 nm or more and 24 nm or less. In this specification, the primary particle diameter of the carbon black means the average value of the diameters (the longest diameter in the case of non-spherical particles) of the carbon black primary particles existing independently and / or the carbon black primary particles constituting the carbon black aggregates. The diameter of the carbon black primary particles is determined by observation with an electron microscope (for example, a transmission electron microscope). The nitrogen adsorption specific surface area of the carbon black (D) is 60 m ２ / g or more and 360 m ２ / g or less, preferably 92 m ２ / g or more and 260 m ２ / g or less, more preferably 110 m ２ / g or more and 260 m ２is 1 g or less. The nitrogen adsorption specific surface area of the carbon black in this specification is the total specific surface area calculated including the area of the pore walls of the carbon black, and is determined based on JIS K6217. The volatile content of the carbon black is 1.1% by weight or more and 10% by weight or less, preferably 1.5% by weight or more and 8% by weight or less, more preferably 1.5% by weight or more and 5% by weight or less. The volatile component of the carbon black in this specification is a component generated when the carbon black is placed in a crucible and heated at 950 °C for 7 minutes, and the surface functional groups of the carbon black are desorbed, and is CO, CO ２ , H ２ 2O, etc. The amount of the volatile component is calculated by substituting the weights of the carbon black before and after the heating into the following formula. Amount of volatile component (%) = 100 × (weight of carbon black before heating − weight of carbon black after heating) / weight of carbon black before heating In the above carbon black (D), x defined by the following formula (1) is 1 or more and 430 or less, preferably 20 or more and 430 or less, more preferably 43 or more and 101 or less, still more preferably 57 or more and 101 or less. The unit of x is (m ２ 2·atom% / g). x = a × S (1) (In the formula, a is the concentration of oxygen double-bonded to carbon on the carbon black surface (unit: atom%), and S is the nitrogen adsorption specific surface area of the carbon black (unit: m ２ 2 / g).) x defined by formula (1) represents the amount of oxygen double-bonded to carbon on the carbon black surface per unit weight of the carbon black. The oxygen concentration a is determined by the following method. Regarding carbon black, X-ray photoelectron spectroscopy (hereinafter referred to as XPS) is used to measure the XPS spectra derived from the C1s, O1s, and S2p electron orbits. For the measurement of the XPS spectrum, for example, AXIS ULTRA DLD manufactured by KRATOS ANALYTICAL is used, and for the analysis, for example, Vision Processing is used. As the X-ray source, AlKα rays (1486.6 eV) are used, and the degree of vacuum inside the apparatus is 10 -９ in the order of torr. The concentration of oxygen atoms on the surface of carbon black (hereinafter referred to as surface oxygen concentration) is the ratio of the number of oxygen atoms on the surface of carbon black to the total of the number of oxygen atoms, carbon atoms, and sulfur atoms on the surface, and is determined by the following method. Specifically, the peak areas of the C1s, O1s, and S2p spectra are obtained, and for C1s, a relative sensitivity coefficient of 0.278, for O1s, 0.780, and for S2p, 0.668 are used, and it is obtained from the following formula. Surface oxygen concentration (atom%) = 100×(c / 0.780) / (b / 0.278 + c / 0.780 + d / 0.668) (In the formula, b is the total area of all peaks of the C1s spectrum, c is the total area of all peaks of the O1s spectrum, and d is the total area of all peaks of the S2p spectrum.) Next, the peak of the O1s spectrum is separated into four components: a peak derived from oxygen double-bonded to carbon (peak top at about 531.0 eV), a peak derived from oxygen single-bonded to carbon having an sp3 orbital (peak top at about 533.0 eV), a peak derived from oxygen single-bonded to carbon having an sp2 orbital (peak top at about 535.0 eV), and a satellite peak due to the process accompanied by π-π ＊ transition (peak top at about 537.5 eV) by peak fitting using a Gaussian function. Let a be the product of the ratio of the area of the peak derived from oxygen double-bonded to carbon to c and the surface oxygen concentration (unit: atom%). Note that the chemical shift values of the oxygen peaks in each structure are referred to the literature (J.M. PENA et al, Journal of Materials Science, 36(2001)2885). The content of the carbon black (D) contained in the composition of the present invention is 0.001 parts by weight or more and 1.7 parts by weight or less, preferably 0.005 parts by weight or more and 1.3 parts by weight or less, more preferably 0.005 parts by weight or more and 0.9 parts by weight or less, based on 100 parts by weight of the propylene-based polymer (A). When the composition contains the propylene-based polymer (A) and the ethylene-α-olefin copolymer (B), the content of the carbon black (D) is 0.001 parts by weight or more and 1.5 parts by weight or less, preferably 0.005 parts by weight or more and 1.1 parts by weight or less, more preferably 0.005 parts by weight or more and 0.8 parts by weight or less, based on 100 parts by weight of the total weight of the propylene-based polymer (A) and the ethylene-α-olefin copolymer (B). The composition of the present invention may contain a pigment dispersant (E). As the pigment dispersant (E), lithium stearate, magnesium stearate, zinc stearate, and polyethylene wax are preferable, lithium stearate and zinc stearate are more preferable, and lithium stearate is further preferable. The pigment dispersant (E) contained in the composition may be one kind or two or more kinds. The content of the pigment dispersant (E) contained in the composition is preferably 0.1 to 3.3 parts by weight, more preferably 0.2 to 1.2 parts by weight, and further preferably 0.2 to 0.9 parts by weight, based on 100 parts by weight of the propylene-based polymer (A). When the composition contains the propylene-based polymer (A) and the ethylene-α-olefin copolymer (B), the content of the pigment dispersant (E) is preferably 0.1 to 2.8 parts by weight, more preferably 0.2 to 1.0 parts by weight, and further preferably 0.2 to 0.8 parts by weight, based on 100 parts by weight of the total weight of the propylene-based polymer (A) and the ethylene-α-olefin copolymer (B). The method for producing the propylene-based polymer composition of the present invention includes a method of kneading a propylene-based polymer (A), carbon black (D), and, if necessary, an ethylene-α-olefin copolymer (B), an inorganic filler (C), a pigment dispersant (E), etc. using a kneader. Examples of the kneader include a single-screw extruder, a twin-screw extruder, a Banbury mixer, a hot roll, etc. The propylene-based polymer (A), carbon black (D), and, if necessary, the ethylene-α-olefin copolymer (B), inorganic filler (C), pigment dispersant (E), etc. may be simultaneously supplied to the kneader and kneaded, or may be supplied separately and kneaded. The kneading temperature is usually 170 to 250°C, preferably 190 to 230°C. The kneading time is usually 1 to 20 minutes, preferably 3 to 15 minutes. In the propylene-based polymer composition of the present invention, additives may be further blended as necessary in addition to the above components (A) to (E). Examples of such additives include antioxidants, ultraviolet absorbers, lubricants, pigments other than carbon black, antistatic agents, copper poisoning preventives, flame retardants, neutralizing agents, foaming agents, plasticizers, nucleating agents, anti-foaming agents, crosslinking agents, etc. The injection molded article of the present invention is an injection molded article made of the propylene-based polymer composition of the present invention, and is produced by injection molding the propylene-based polymer composition of the present invention. A known injection molding method can be applied to the injection molding. The injection molded article of the present invention is preferably an injection molded article for automobiles, and this is incorporated into an automobile as an automobile member. Examples of the automobile member composed of the injection molded article of the present invention include a door trim, a back door trim, a pillar, a glove box, a column cover, a bumper, a side mold, an instrument panel, a console, etc. Hereinafter, the present invention will be described by way of examples and comparative examples, but the present invention is not limited to these examples. The components used in the examples and comparative examples are shown below. (1) Propylene-based polymer (A) Heterophasic propylene-based polymer Using the polymerization catalyst prepared by the method described in Example 1 of JP-A-2004-182981, a heterophasic propylene-based polymer containing 77 parts by weight of the following (a) propylene homopolymer component and 23 parts by weight of (b) ethylene-propylene random copolymer component was produced by a liquid phase-gas phase polymerization method. (a) Propylene homopolymer component: Molecular weight distribution 6.6 Isotactic pentad fraction 0.98 Intrinsic viscosity 1.2 dl / g (b) Ethylene-propylene random copolymer: Intrinsic viscosity 3.7 dl / g Content of monomer units derived from ethylene 30% by weight (2) Ethylene-α-olefin copolymer (B) Manufactured by DuPont Dow Elastomers, Engage EG8200 Ethylene-octene-1 copolymer Content of monomer units derived from ethylene 61.7% by weight (content of monomer units derived from octene-1 38.3% by weight) (3) Inorganic filler (C) Talc manufactured by Hayashi Kasei Co., Ltd. (equivalent particle size D ５０ = 2.9 μm) (4) Carbon black (D) Six types of carbon blacks D1 to D6 were used. The physical properties (pH, primary particle size, nitrogen adsorption surface area, volatile component content) of these carbon blacks, a in the above formula (1), and x defined by the above formula (1) are shown in Table 1 below. (5) Pigment dispersant (E) Lithium stearate The measurement methods of the physical properties of the polymer compositions used in the examples and comparative examples are shown below. (1) Thermal stability (1-1) Evaluation method A gear oven life test was carried out using test pieces punched out from a press-formed body manufactured by the method described below. The test pieces were placed in a gear oven at 160 °C, taken out every day, bent with fingers, and checked for cracks. When cracks occurred in the test pieces due to bending, the GOL test of the sample was terminated at that point, and the total time the test pieces had been in the oven until this point was defined as the gear oven life (hereinafter referred to as GOL; unit: hours). The longer the GOL, the better the thermal stability of the sample. (1-2) Manufacture of press-formed body The press-formed body for the above thermal stability evaluation was manufactured according to the following method. The composition was heated at 230 °C for 5 minutes under normal pressure using a hot press machine, then pressurized at 230 °C for 5 minutes at 3 MPa, and further cooled at room temperature for 5 minutes at 5 MPa to obtain a press-formed body which was a press sheet with a thickness of 1 mm. This sheet was punched out with a punching blade to obtain disk-shaped test pieces with a diameter of 25 mm and a thickness of 1 mm. (2) Appearance The appearance of a flat plate with a length of 100 mm × width of 150 mm × thickness of 3 mm molded by the following injection molding was visually observed and evaluated according to the following criteria. Good: When streak-like color unevenness is not noticeable in the molded body, it is judged that the appearance is good and indicated by the symbol ○ in the following table. Bad: When streak-like color unevenness is noticeable in the molded body, it is judged that the appearance is bad and indicated by the symbol × in the following table. Also, if necessary, the specular glossiness, which is one of the appearance indexes, was measured. The measurement was carried out at a measurement angle of 60 degrees using a specular glossiness meter at the center of the disk-shaped test piece manufactured in the same manner as the method described in (1-2) above. The larger the value of the specular glossiness, the better the surface of the molded body is colored with gloss and the better the surface finish. [Manufacture of injection molded body] The injection molded body for the above appearance evaluation was manufactured according to the following method. After thoroughly drying the composition in a hot air dryer, injection molding was carried out using a Toshiba Machine SH100C injection molding machine at a molding temperature of 220°C, a mold cooling temperature of 50°C, an injection time of 10 seconds, and a cooling time of 20 seconds to obtain an injection molded article with dimensions of 100 mm in length × 150 mm in width × 3 mm in thickness. [Example 1] [Production of Propylene-Based Polymer Composition] The propylene-based polymer composition was produced according to the following method. 88 parts by weight of a propylene-based polymer (A), 12 parts by weight of an ethylene-α-olefin copolymer (B), 27 parts by weight of an inorganic filler (C), 0.5 part by weight of carbon black (D1), and 0.4 part by weight of a pigment dispersant (E) were preliminarily mixed uniformly in a tumbler and then kneaded and extruded using an extruder to produce a composition. The evaluation results of the composition are shown in Table 2. [Examples 2 - 3, Comparative Examples 1 - 3] A composition was produced in the same manner as in Example 1 except that the carbon black was changed to that described in Table 2. The evaluation results of the composition are shown in Table 2. [Comparative Examples 5 - 6] A composition was produced in the same manner as in Example 1 except that each of the propylene-based polymer (A) and the ethylene-α-olefin copolymer (B) was changed as described in Table 3. The evaluation results of the composition are shown in Table 3. Examples 1 - 3 are propylene-based polymer compositions that satisfy the requirements of the present invention, have good thermal stability, and can give molded articles with good appearance when molded. In contrast, the carbon black contained in the composition described in Comparative Example 1 did not satisfy the requirements of the present invention regarding the primary particle diameter, nitrogen adsorption specific surface area, volatile component content, and x defined by formula (1), and the thermal stability of the composition was poor. The carbon black contained in the composition described in Comparative Example 2 did not satisfy the requirements of the present invention regarding the volatile component content and x defined by formula (1), and the thermal stability of the composition was poor. The carbon black contained in the composition described in Comparative Example 3 did not satisfy the requirements of the present invention regarding the primary particle diameter, nitrogen adsorption specific surface area, and volatile component content, and the appearance of the molded body made of the composition was poor. The amounts of the ethylene-α-olefin copolymer contained in the compositions described in Examples 5 and 6 did not satisfy the requirement of the preferred embodiment of the present invention, "the content of the ethylene-α-olefin copolymer (B) is 1 part by weight or more and 14 parts by weight or less", and the specular glossiness was lower than that of Example 1.

Claims

Revised on 21 / 04 / 2026.

1. A polypropylene-based polymer composition consisting of a polypropylene-based polymer (A), of which at least one polypropylene-based polymer is selected from a group consisting of polypropylene homopolymer (A-1) and polypropylene-based polymer mixed phase (A-2), and carbon black (D), where the amount of carbon black (D) is 0.001 parts by weight or more and 1.7 parts by weight or less relative to the total amount of the polymer. A propylene-based nitrogen (A) particle size of 100 parts by weight, primary particle size of carbon black (D) is 15 nm or greater and 39 nm or less, and x, which is defined by the following formula (1), is 20 or greater and 430 or less: x=axS(1), where, a is the concentration (unit: % by atom) of oxygen double bonded to carbon on the surface of the carbon black, and S is the specific surface area for nitrogen adsorption (unit: m² / g) of the carbon black. Page 1 of Number 2, Claim 1.A polypropylene-based polymer composition consisting of a polypropylene-based polymer (A) as at least one polypropylene-based polymer selected from a group of polypropylene homopolymer (A-1) and polypropylene-based polymer mixed phase (A-2), and carbon black (D), where the amount of carbon black (D) is 0.001 p / g or more and 1.7 p / g or less, with a total weight of polypropylene-based polymer (A) of 100 p / g, the primary particle size of the carbon black described above (D) is 15 nm or more and 39 nm or less, and x, which is defined by the following formula (1), is 1 or more and 430 or less: x=aXS(1)(where a is the concentration (unit: % by atom) of oxygen double-bonded to carbon on the surface of the carbon black, and S is the specific surface area for nitrogen adsorption (unit: m² / g) of the carbon black).

3. Propylene-based polymer compositions under Reputation 1 or 2 where the propylene-based polymer (A) includes propylene homopolymer (A-1) and a mixed-phase propylene-based polymer (A-2), and the mixed-phase propylene-based polymer described above (A-2) consists of a propylene homopolymer (A-2-1) and a propylene-ethylene copolymer (A-2-2) with an intrinsic viscosity of 2.0 deciliters / gram or more and 10.0 deciliters / gram or less. 4.A polypropylene-based polymer composition under one of the claims 1 through 3 that also includes ethylene-(formula)-olefin copolymer (B) as at least one ethylene-(formula)-olefin copolymer which is selected from a group consisting of ethylene-(formula)-olefin copolymer (B-1) with monomer units derived from ethylene and monomer units derived from (formula)-olefin with 4 or more carbon atoms and ethylene-propylene copolymer (B-2), page 2 of On page 2, the amount of propylene-based polymer (A) is 86 parts by weight or more and 99 parts by weight or less, and the amount of ethylene-(formula)-olefin copolymer (B) is 1 part by weight or more and 14 parts by weight or less, with the total weight of propylene-based polymer (A) and ethylene-(formula)-olefin copolymer (B) being 100 parts by weight, the amount of carbon black (D) is 0.001 parts by weight or more and 1.

5. By weight or less, the amount of ethylene-derived monomer units contained in the ethylene-(formula)-olefin copolymer described above (B-1) is 40% by weight or more and 99% by weight or less (provided that the total weight of the ethylene-(formula)-olefin copolymer (B-1) is 100% by weight), and the ethylene-propylene copolymer (B-2) described above has an intrinsic viscosity of 0.1 dL / g or more and less than 2.0 dL / g.

5. Injection molded products containing a propylene-based polymer composition according to any of the claims 1 through 4;