Resin composition and molded article

Abstract

To provide a resin composition excellent in low-temperature impact resistance.SOLUTION: A resin composition comprising: polypropylene; and at least one selected from the group consisting of a styrene-ethylene-ethylene-propylene-styrene block copolymer and an ethylene - α - olefin copolymer having a melting point of 100 °C or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a resin composition and a molded article. [Background technology]

[0002] Patent Document 1 discloses a propylene-based resin composition and a molded article formed from the propylene-based resin composition. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-36390 Summary of the Invention [Problem to be solved by the invention]

[0004] However, molded articles of conventional resin compositions do not have sufficient low-temperature impact resistance, and therefore, there is a demand for resin compositions that are excellent in low-temperature impact resistance. The present disclosure has an object to provide a resin composition having excellent low-temperature impact resistance. The present disclosure can be realized in the following aspects. [Means for solving the problem]

[0005] [1] Polypropylene, one or more selected from the group consisting of styrene-ethylene-ethylene-propylene-styrene block copolymers and ethylene-α-olefin copolymers having a melting point of 100°C or less; A resin composition comprising: [Effects of the Invention]

[0006] According to the present disclosure, a resin composition having excellent low-temperature impact resistance can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0007] Here, a preferred example of the present disclosure will be described. [2] The resin composition according to [1], which contains one or more selected from the group consisting of carbon black, organic dyes, and inorganic pigments. [3] The resin composition according to [1], wherein the haze based on JIS K 7136 is 60% or more and 90% or less. [4] A molded article of the resin composition according to any one of [1] to [3].

[0008] The present disclosure will be described in detail below. 1. First embodiment The resin composition of the first embodiment contains polypropylene and one or more selected from the group consisting of a styrene-ethylene-ethylene-propylene-styrene block copolymer and an ethylene-α-olefin copolymer having a melting point of 100° C. or less. The resin composition preferably contains one or more selected from the group consisting of carbon black, an organic dye, and an inorganic pigment.

[0009] 1-1. Components of resin composition (1) Polypropylene The polypropylene is preferably one or more types selected from the group consisting of random polypropylene, block polypropylene, and homopolypropylene. Among these, from the viewpoint of flexibility and impact resistance, the polypropylene preferably includes block polypropylene. Only one type of polypropylene may be used, or two or more types may be used in combination.

[0010] The polypropylene content is preferably 50 parts by mass or more, more preferably 75 parts by mass or more, and even more preferably 85 parts by mass or more, relative to 100 parts by mass of the total resin raw materials (polypropylene, styrene-ethylene-ethylene-propylene-styrene block copolymer, and ethylene-α-olefin copolymer; the same applies hereinafter). The polypropylene content is preferably 97 parts by mass or less, more preferably 93 parts by mass or less, and even more preferably 90 parts by mass or less. From these viewpoints, the polypropylene content is preferably 50 parts by mass or more and 97 parts by mass or less, more preferably 75 parts by mass or more and 93 parts by mass or less, and even more preferably 85 parts by mass or more and 90 parts by mass or less.

[0011] Examples of random polypropylenes include propylene-ethylene random copolymers (for example, metallocene PP polymerized by a metallocene catalyst).

[0012] The melt flow rate of the random polypropylene (JIS K7210, 230°C, 2.16 kg) is not particularly limited. From the viewpoint of moldability, the melt flow rate of the random polypropylene is preferably 1 g / 10 min or more and 200 g / 10 min or less, more preferably 10 g / 10 min or more and 150 g / 10 min or less, and even more preferably 25 g / 10 min or more and 100 g / 10 min or less.

[0013] The content of the random polypropylene is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, when the total amount of the resin raw materials is 100 parts by mass, from the viewpoint of improving transparency. From the viewpoint of ensuring impact resistance, the content of the random polypropylene is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less. From these viewpoints, the content of the random polypropylene is preferably 20 parts by mass or more and 70 parts by mass or less, more preferably 30 parts by mass or more and 60 parts by mass or less, and even more preferably 40 parts by mass or more and 50 parts by mass or less.

[0014] Block polypropylene is a polymer with a sea-island structure in which an ethylene-based resin is dispersed in polypropylene. Block polypropylene is a type of propylene block copolymer in the broad sense. Block polypropylene is a polymer that contains, for example, approximately 10% by mass to 50% by mass of island phases of polyethylene components and / or ethylene-propylene copolymer components in a polypropylene sea phase, and is also called a heterophase copolymer. Unlike ethylene-propylene block copolymers in the narrow sense, homopolypropylene chains and polyethylene chains or ethylene-propylene copolymer chains are not necessarily chemically bonded. In general block polypropylene, polyethylene island phases are dispersed in a polypropylene sea phase while being covered with ethylene-propylene copolymer.

[0015] The heterophase copolymer described above can be produced, for example, by first polymerizing propylene homopolymer and then copolymerizing ethylene or the like. The sea-island structure can be controlled by adjusting the ratio of the ethylene component, the number of chains, and the molecular weight of the PP. Various products are commercially available, and any type of block polypropylene can be used in the present disclosure. Block polypropylenes generally have excellent flexibility and impact resistance. It is believed that the use of block polypropylene can contribute to improvements in flexibility, impact resistance, and the like, compared to the use of, for example, propylene homopolymer or narrowly defined ethylene-propylene block copolymer. Only one type of block polypropylene may be used, or two or more types may be used in combination.

[0016] The melt flow rate of the block polypropylene (based on JIS K7210, 230°C, 2.16 kg) is not particularly limited. From the viewpoint of moldability, the melt flow rate of the block polypropylene is preferably 1 g / 10 min or more and 200 g / 10 min or less, more preferably 10 g / 10 min or more and 150 g / 10 min or less, and even more preferably 25 g / 10 min or more and 100 g / 10 min or less.

[0017] The density of the block polypropylene is not particularly limited. The density of the block polypropylene is 0.89 g / cm 3 More than 0.92g / cm 3 The density can be measured as follows: The density is measured in accordance with JIS K7112.

[0018] The content of the block polypropylene is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, when the total amount of the resin raw materials is 100 parts by mass, from the viewpoint of improving impact resistance. From the viewpoint of ensuring transparency, the content of the block polypropylene is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less. From these viewpoints, the content of the block polypropylene is preferably 20 parts by mass or more and 70 parts by mass or less, more preferably 30 parts by mass or more and 60 parts by mass or less, and even more preferably 40 parts by mass or more and 50 parts by mass or less.

[0019] (2) Styrene-ethylene-ethylene-propylene-styrene block copolymer Styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS) is a thermoplastic elastomer, a hydrogenated block copolymer having block units of a polymer made of a styrene-based monomer and block units of a polymer made of a conjugated diene compound.

[0020] The melt flow rate of the styrene-ethylene-ethylene-propylene-styrene block copolymer (based on JIS K7210, 230°C, 2.16 kg) is not particularly limited. From the viewpoint of moldability, the melt flow rate of the styrene-ethylene-ethylene-propylene-styrene block copolymer is preferably 0.3 g / 10 min or more and 2.0 g / 10 min or less, more preferably 0.5 g / 10 min or more and 1.5 g / 10 min or less, and even more preferably 0.8 g / 10 min or more and 1.2 g / 10 min or less.

[0021] The content of the styrene-ethylene-ethylene-propylene-styrene block copolymer is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, from the viewpoint of improving impact resistance, when the total amount of the resin raw materials is 100 parts by mass. From the viewpoint of ensuring rigidity, the content of the styrene-ethylene-ethylene-propylene-styrene block copolymer is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 16 parts by mass or less. From these viewpoints, the content of the styrene-ethylene-ethylene-propylene-styrene block copolymer is preferably 2 parts by mass or more and 30 parts by mass or less, more preferably 5 parts by mass or more and 20 parts by mass or less, and even more preferably 7 parts by mass or more and 16 parts by mass or less.

[0022] (3) Ethylene-α-olefin copolymer The ethylene-α-olefin copolymer is, for example, a copolymer having structural units derived from ethylene and structural units derived from at least one α-olefin selected from α-olefins having 4 to 10 carbon atoms. The ethylene-α-olefin copolymer may be any of a random copolymer, a block copolymer, and a graft copolymer.

[0023] The melting point of the ethylene-α-olefin copolymer used in the resin composition of the first embodiment is 90°C or lower, preferably 80°C or lower, and more preferably 70°C or lower. The melting point of the ethylene-α-olefin copolymer is preferably 50°C or higher, more preferably 55°C or higher, and even more preferably 60°C or higher. Therefore, the melting point of the ethylene-α-olefin copolymer is 100°C or lower, preferably 50°C or higher and 90°C or lower, more preferably 55°C or higher and 80°C or lower, and even more preferably 60°C or higher and 70°C or lower.

[0024] Specific examples of the α-olefin having 4 to 10 carbon atoms used in the ethylene-α-olefin copolymer include one or more selected from the group consisting of 1-butene, 1-octene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-decene, and α-olefins having a cyclic structure. 1-Butene is preferred as the α-olefin.

[0025] Specific examples of the ethylene-α-olefin copolymer include ethylene-1-butene copolymer (EBR), ethylene-1-octene copolymer, ethylene-1-hexene copolymer, ethylene-1-decene copolymer, ethylene-(3-methyl-1-butene) copolymer, and copolymers of ethylene and an α-olefin having a cyclic structure.

[0026] The melt flow rate of the ethylene-α-olefin copolymer (according to ASTM D1238, 230°C, 2.16 kg) is not particularly limited. From the viewpoint of moldability, the melt flow rate of the ethylene-α-olefin copolymer is preferably 1.0 g / 10 min to 3.0 g / 10 min, more preferably 1.5 g / 10 min to 3.0 g / 10 min, and even more preferably 2.0 g / 10 min to 2.5 g / 10 min.

[0027] The density of the ethylene-α-olefin copolymer is not particularly limited. The density of the ethylene-α-olefin copolymer is 0.85 g / cm 3 More than 0.90g / cm 3 The density can be measured as follows: The density is measured in accordance with ASTM D1505.

[0028] The content of the ethylene-α-olefin copolymer is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, from the viewpoint of improving impact resistance, when the total amount of the resin raw materials is 100 parts by mass. From the viewpoint of ensuring rigidity, the content of the ethylene-α-olefin copolymer is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 16 parts by mass or less. From these viewpoints, the content of the ethylene-α-olefin copolymer is preferably 2 parts by mass or more and 30 parts by mass or less, more preferably 5 parts by mass or more and 20 parts by mass or less, and even more preferably 7 parts by mass or more and 16 parts by mass or less.

[0029] (4) Total content of styrene-ethylene-ethylene-propylene-styrene block copolymer and ethylene-α-olefin copolymer The total content of the styrene-ethylene-ethylene-propylene-styrene block copolymer and the ethylene-α-olefin copolymer is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, from the viewpoint of improving impact resistance, when the total amount of the resin raw materials is 100 parts by mass. From the viewpoint of ensuring rigidity, the total content of the styrene-ethylene-ethylene-propylene-styrene block copolymer and the ethylene-α-olefin copolymer is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. From these viewpoints, the total content of the styrene-ethylene-ethylene-propylene-styrene block copolymer and the ethylene-α-olefin copolymer is preferably 3 parts by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more and 30 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less.

[0030] (5) Black colorant The black colorant may be either a black pigment or a black dye, and preferably includes carbon black and / or an organic dye.

[0031] The type of carbon black is not particularly limited, and the carbon black may be, for example, one or more types selected from the group consisting of furnace black, ketjen black, and acetylene black.

[0032] The average particle size of carbon black is preferably 3 nm or more, more preferably 5 nm or more, and even more preferably 8 nm or more, from the viewpoint of facilitating mixing in the resin composition. The average particle size of carbon black is preferably 40 nm or less, more preferably 30 nm or less, and even more preferably 20 nm or less, from the viewpoint of imparting a jet black feel to the resin composition. From these viewpoints, the average particle size of carbon black is preferably 3 nm or more and 40 nm or less, more preferably 5 nm or more and 30 nm or less, and even more preferably 8 nm or more and 20 nm or less.

[0033] The carbon black content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.8 parts by mass or more, from the viewpoint of imparting a jet-black appearance to the resin composition, when the total amount of the resin raw materials is 100 parts by mass. From the viewpoint of maintaining moldability, the carbon black content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 2 parts by mass or less. From these viewpoints, the carbon black content is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.5 parts by mass or more and 5 parts by mass or less, and even more preferably 0.8 parts by mass or more and 2 parts by mass or less.

[0034] (6) Inorganic pigments The inorganic pigment has a function of imparting a metallic color tone to the resin composition, and examples of the inorganic pigment include metallic pigments, spherical aluminum pigments, mica powder, and metal-coated inorganic polyhedral particles.

[0035] Metallic pigments are flat pigments such as aluminum foils or glass flakes coated with a metal. Spherical aluminum pigments are used to improve the appearance of welds. Mica powder is a pearlescent metallic pigment. Metal-coated inorganic polyhedral particles are inorganic polyhedral particles such as copper powder, brass powder, or glass coated with a metal by plating or sputtering to obtain a bronze color tone.

[0036] Examples of the inorganic polyhedral particles include glass, crushed thin glass films, and metals. Examples of metals include Ni, Al, Ag, Cu, Cr, Zn, Sn, Pb, Co, Fe, Mo, Mn, W, Au, Ti, Sb, Si, Pt, and Mg. At least one metal selected from these metals, or compounds thereof such as alloys, oxides, nitrides, and sulfides, or mixtures thereof, can be used.

[0037] As described above, inorganic pigments are metals or metal compounds themselves, or metals or metal compounds attached to glass, mica, or the like by plating, vapor deposition, or other methods. Inorganic pigments also include those coated with organic substances such as fatty acids to protect the metal surface, or with titanium oxide, silica, or the like. Since the color tone of the resulting metallic resin molded product varies depending on the inorganic pigment used, the inorganic pigment is appropriately selected and used depending on the desired color tone. Furthermore, the desired color tone can be achieved by combining an inorganic pigment with an existing colorant typically blended into resins and adjusting the type and amount of each.

[0038] The content of the inorganic pigment is not particularly limited. When the total amount of the resin raw materials is 100 parts by mass, the content of the inorganic pigment is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less, from the viewpoint of suppressing deterioration of physical properties and molding defects of molded articles using the resin composition. The content of the inorganic pigment is preferably 0.05 parts by mass or more, more preferably 0.08 parts by mass or more, and even more preferably 0.1 parts by mass or more, from the viewpoint of obtaining a sufficient color tone due to the inorganic pigment. From these viewpoints, the content of the inorganic pigment is preferably 0.05 parts by mass or more and 5.0 parts by mass or less, more preferably 0.08 parts by mass or more and 4.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 3.0 parts by mass or less.

[0039] Inorganic pigments are usually present in the form of fine powder, and from the viewpoints of preventing dust explosions, improving the working environment, etc., inorganic pigments may be used in the form of a so-called masterbatch in which the inorganic pigment is pre-kneaded with a styrene-based resin or the like, as needed. There are no particular restrictions on the amount of inorganic pigment contained in the masterbatch, but it is, for example, 10% by weight or more and 90% by weight or less.

[0040] (7) Dispersant The resin composition preferably contains a dispersant. Examples of dispersants that can be used include polyethylene wax, ester wax, and fatty acid metal soaps. The number-average molecular weight of the polyethylene wax is preferably 300 or more and 8000 or less, and more preferably 1000 or more and 5000 or less. Low-molecular-weight polyethylene and its derivatives can be used as the polyethylene wax. If the number-average molecular weight of the polyethylene wax is less than 300, the pigment dispersibility is excellent, but the processability tends to be reduced. On the other hand, if the number-average molecular weight of the polyethylene wax exceeds 8000, the processability tends to be reduced. Examples of fatty acid metal soaps include zinc stearate, calcium stearate, lithium stearate, magnesium stearate, and sodium palmitate.

[0041] The content of the dispersant is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, when the total amount of the resin raw materials is 100 parts by mass. The content of the dispersant is preferably 1.0 part by mass or less, more preferably 0.8 parts by mass or less, and even more preferably 0.5 parts by mass or less. Therefore, the content of the dispersant is preferably 0.1 part by mass or more and 1.0 part by mass or less, more preferably 0.05 parts by mass or more and 0.8 parts by mass or less, and even more preferably 0.1 part by mass or more and 0.5 parts by mass or less.

[0042] (8) Antioxidants The resin composition preferably contains an antioxidant, such as a hindered phenol-based antioxidant, a phosphorus-based antioxidant, a hindered amine-based antioxidant, or a sulfur-based antioxidant, and among these, hindered phenol-based antioxidants and phosphorus-based antioxidants are preferred.

[0043] Examples of hindered phenol antioxidants include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and the like. 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 4-methyl-2,6-di-t-butylphenol, triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, C7-C9 side chain alkyl ester, 2,4-bis[(octylthio)methyl]-o-cresol, 2,4-bis[(dodecylthio)methyl]-6-methylphenol, 3,9-bis[1,1-dimethyl-2-[(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, and the like. Among these, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] is preferred.

[0044] Examples of phosphorus-based antioxidants include tris(2-ethylhexyl) phosphite, tris(dipropylene glycol) phosphite, triphenyl phosphite, tristearyl phosphite, and bis(tridecyl)pentaerythritol diphosphite.

[0045] The content of the antioxidant is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.08 parts by mass or more, when the total amount of the resin raw materials is 100 parts by mass. The content of the antioxidant is preferably 0.20 parts by mass or less, more preferably 0.15 parts by mass or less, and even more preferably 0.12 parts by mass or less. Therefore, the content of the antioxidant is preferably 0.01 parts by mass or more and 0.20 parts by mass or less, more preferably 0.05 parts by mass or more and 0.15 parts by mass or less, and even more preferably 0.08 parts by mass or more and 0.12 parts by mass or less.

[0046] (9) Weatherproofing agent The resin composition preferably contains a weathering agent. A weathering agent is an additive for suppressing deterioration of the resin composition due to outdoor natural environments such as sunlight, temperature, humidity, and rain. Examples of weathering agents include ultraviolet absorbers for absorbing ultraviolet rays and light stabilizers for stabilizing radicals generated by ultraviolet rays. The resin composition of the present disclosure may contain any one of these weathering agents, or may contain two or more of them.

[0047] As the weatherproofing agent, for example, a NOR type hindered amine compound is preferably used. A light stabilizer containing a NOR type hindered amine compound as the main component is, for example, a mixture of a high molecular weight hindered amine light stabilizer and a sterically hindered hindered amine light stabilizer, and a low basicity weatherproofing stabilizer system can be preferably used. Note that the NOR type hindered amine compound is a hindered amine compound in which the H of the imino group (>NH) of the piperidine ring is substituted with an alkoxyl group (-OR).

[0048] The content of the weather resistant agent is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.08 parts by mass or more, when the total amount of the resin raw materials is 100 parts by mass. The content of the weather resistant agent is preferably 1.00 parts by mass or less, more preferably 0.75 parts by mass or less, and even more preferably 0.50 parts by mass or less. Therefore, the content of the weather resistant agent is preferably 0.01 parts by mass or more and 1.00 parts by mass or less, more preferably 0.05 parts by mass or more and 0.75 parts by mass or less, and even more preferably 0.08 parts by mass or more and 0.50 parts by mass or less.

[0049] (10) Other ingredients The resin composition may contain a release agent, a filler, a processing aid, a lubricant, a pigment other than carbon black, a function-imparting agent (for example, a flame retardant), and the like, as needed.

[0050] (11) Melt flow rate of resin composition From the viewpoint of moldability, the melt flow rate of the resin composition (according to JIS K 7210, 230°C, 2.16 kg) is preferably 5 g / 10 min or more and 35 g / 10 min or less, more preferably 10 g / 10 min or more and 30 g / 10 min or less, and even more preferably 15 g / 10 min or more and 25 g / 10 min or less.

[0051] (12) Haze of Resin Composition The haze of the resin composition according to JIS K 7136 is preferably 60% to 90%, more preferably 65% ​​to 85%, and even more preferably 70% to 80%. The test piece of the resin composition used to measure the haze is a small square plate type D (60 mm x 60 mm x 2 mm thick) as specified in JIS K 7139:2009. The haze is measured using a test device (manufactured by Nippon Denshoku Industries Co., Ltd., product name: NDH8000). The haze is measured, for example, on a resin composition that does not contain carbon black, organic dyes, or inorganic pigments.

[0052] 1-2.Method for producing resin composition The resin composition of the first embodiment is produced, for example, by melt-kneading a mixture of the above components. Alternatively, the resin composition may be produced, for example, by dissolving the above components in a solvent. The melt-kneading means is not particularly limited, and examples thereof include a twin-screw extruder, a Henschel mixer, a Banbury mixer, a single-screw extruder, a multi-screw extruder, and a co-kneader.

[0053] 1-3. Molded body The resin composition of the first embodiment can be used as a molding material for various molded articles. The resin composition of the first embodiment can be formed into molded articles with excellent low-temperature impact resistance, and is therefore suitable for, for example, automobile interior and exterior components. Examples of automobile interior components include pillars, instrument panels, door trims, and console boxes. Examples of automobile exterior components include spoilers, bumpers, fenders, door panels, and trunk lids. The resin composition of the first embodiment can also be used for the exterior of home appliances.

[0054] Examples of methods for molding the resin composition into a molded article include injection molding, extrusion molding, blow molding, heat press molding, calendar molding, coating molding, cast molding, vacuum molding, and transfer molding.

[0055] 1-4. Physical properties of molded products (1) Tensile test The tensile strength, breaking strain, and elastic modulus of the molded product in a tensile test (JIS K 7161) are preferably within the following ranges: The tensile test is performed using a dumbbell-shaped tensile test piece type A1 specified in JIS K 7139:2009.

[0056] (1-1) Tensile strength The tensile strength of the molded article based on a tensile test is preferably 10.0 MPa or more, more preferably 15.0 MPa or more, and even more preferably 20.0 MPa or more. The upper limit of the tensile strength is not particularly limited, and is, for example, 50.0 MPa or less.

[0057] (1-2) Fracture strain The fracture strain of the molded article based on a tensile test is preferably 100% or more, more preferably 150% or more, and even more preferably 200% or more. The upper limit of the fracture strain is not particularly limited, and is, for example, 500% or less.

[0058] (1-3) Elastic modulus The elastic modulus of the molded article based on a tensile test is preferably 900 MPa or more, more preferably 950 MPa or more, and even more preferably 1000 MPa or more. The upper limit of the elastic modulus is not particularly limited, and is, for example, 1400 MPa or less.

[0059] (2) Heat deflection temperature (HDT) The deflection temperature under load of the molded article (based on JIS K 7191) is preferably 50° C. or higher, preferably 60° C. or higher, and more preferably 70° C. or higher. There are no particular limitations on the upper limit of the deflection temperature under load, and it is, for example, 100° C. Here, the deflection temperature under load is measured by cutting a test piece (length 80 mm, width 10 mm, thickness 4 mm) from the molded article and using a heat destation tester under the condition of applying a bending stress of 0.45 MPa to the test piece.

[0060] (3) Charpy impact strength The Charpy impact strength (JIS K 7111 compliant) of the molded product at 23°C is 4.0 kJ / m 2 More than 6.0 kJ / m is preferable. 2 More preferably, 8.0 kJ / m or more 2 The upper limit of the Charpy impact strength is not particularly limited, and is, for example, 10.0 kJ / m 2 The Charpy impact strength is measured using a Charpy impact tester (IT manufactured by Toyo Seiki Seisakusho Co., Ltd.).

[0061] The Charpy impact strength of the molded product at -30°C (JIS K 7111 standard) is 1.0 kJ / m 2 More than 1.5kJ / m is preferable. 2 More preferably, 2.0 kJ / m or more 2The upper limit of the Charpy impact strength is not particularly limited, and is, for example, 6.0 kJ / m 2 is.

[0062] (4) Lightness (L* value) The lightness (L* value) of the molded article in the L*a*b* color system according to JIS Z 8781-4 is preferably 3.0 to 5.5, more preferably 3.3 to 5.0, and even more preferably 3.5 to 4.8. The lightness (L* value) is measured using an L*a*b* color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name: SD7000) using a D65 light source as the observation light source, a viewing angle of 10°, and the specular exclusion (SCE) method. The lightness (L* value) is measured, for example, on a molded article containing one or more selected from the group consisting of carbon black, organic dyes, and inorganic pigments.

[0063] 1-5. Effects of the First Embodiment The resin composition and molded article of the first embodiment are excellent in low-temperature impact resistance. Generally, resins containing transparent / semi-transparent polypropylene have poor low-temperature impact resistance. However, the resin composition of the first embodiment contains one or more selected from the group consisting of styrene-ethylene-ethylene-propylene-styrene block copolymers and ethylene-α-olefin copolymers having a melting point of 100°C or less, thereby improving low-temperature impact resistance. The resin composition and molded article of the first embodiment can be widely used as automobile interior and exterior parts. The resin composition and molded article of the first embodiment contain one or more selected from the group consisting of carbon black, organic dyes, and inorganic pigments, which eliminates the need for painting, makes them easy to recycle, and is environmentally friendly from the perspective of being carbon neutral. In the resin composition and molded article of the first embodiment, when one or more selected from the group consisting of carbon black, organic dyes, and inorganic pigments are contained, the effect of these coloring materials in keeping the brightness (L value) low and the effect of the resin's high transparency (low haze value) in suppressing light scattering combine to enhance the jet black appearance. [Example]

[0064] The present invention will be explained in more detail below with reference to examples. 1. Preparation of resin composition and molded body Resin compositions and molded articles of Examples and Comparative Examples were prepared using the blending ratios shown in Tables 1-3. Details of the raw materials for the resin compositions in Tables 1-3 are shown in Table 4. Comparative Examples 1-4 employ the constitution of a conventionally known resin composition.

[0065] In Table 1-3, the blending ratios represent blending ratios (parts by mass) when the total of the resin raw materials (polypropylene, styrene-ethylene-butylene-styrene block copolymer, linear low-density polyethylene (L-LDPE), styrene-ethylene-ethylene-propylene-styrene block copolymer, and ethylene-α-olefin copolymer) is taken as 100 parts by mass.

[0066] In Tables 1-3, "random polypropylene" is metallocene PP polymerized with a metallocene catalyst, and has a melt flow rate (JIS K7210 compliant, 230°C, 2.16 kg) of 30 g / 10 min.

[0067] In the formulations in Table 1-3, "styrene rubber (SEBS)" is a styrene-ethylene / butylene-styrene block copolymer, and "styrene rubber (SEEPS)" is a styrene-ethylene-ethylene-propylene-styrene block copolymer. Olefin rubber (EBR) is an ethylene-α-olefin copolymer (ethylene-1-butene copolymer) with a melting point of 66°C. Linear low-density polyethylene (L-LDPE) has a melting point of 120°C and a melt flow rate (JIS K7210 compliant, 190°C, 2.16 kg) of 1.2 g / 10 min.

[0068] In the formulations of Tables 1-3, the "phenolic antioxidant" includes pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], the "phosphorus antioxidant" includes tris(2-ethylhexyl)phosphite, and the "weather resistance agent" includes a NOR-type hindered amine compound.

[0069] In Table 1-3, the average particle size of "jet black carbon black" is 8 nm. In Table 1-3, "MFR of resin composition" is the MFR (a numerical value indicating the melt flow rate) of the entire resin composition (a mixture of the above resin raw materials, jet black carbon black, zinc stearate, phenolic antioxidant, phosphorus-based antioxidant, and weathering agent).

[0070] [Table 1]

[0071] [Table 2]

[0072] [Table 3]

[0073] [Table 4]

[0074] 1-2. Preparation of resin compositions and molded articles in examples and comparative examples The raw materials (the resin raw materials, jet black carbon black, zinc stearate, a phenolic antioxidant, a phosphorus-based antioxidant, and a weathering agent) were mixed and melt-kneaded using a twin-screw extruder at a discharge rate of 30 kg / h, a rotation speed of 400 rpm, and 180°C to obtain a pellet-shaped resin composition. The obtained resin composition was injection-molded at 200°C to obtain a molded product.

[0075] 2. Evaluation Method 2-1. Melt flow rate of resin composition The melt flow rate of the resin composition was measured in accordance with JIS K 7210 at a heating temperature of 230° C. and a load of 2.16 kg.

[0076] 2-2. Haze The haze of the resin composition was measured in accordance with JIS K 7136. The test piece of the resin composition used for measuring the haze was a small square plate type D (60 mm × 60 mm × 2 mm thick) as specified in JIS K 7139:2009. The haze was measured using a test device (manufactured by Nippon Denshoku Industries Co., Ltd., product name: NDH8000). The haze measurement was performed on a resin composition that did not contain jet black carbon black (a composition containing the above resin raw materials, zinc stearate, a phenolic antioxidant, a phosphorus-based antioxidant, and a weathering agent).

[0077] 2-3.Tensile test The tensile test of the molded body was carried out based on JIS K 7161 to measure the tensile strength, breaking strain, and elastic modulus. The tensile test was carried out using a dumbbell-shaped tensile test piece type A1 specified in JIS K 7139:2009.

[0078] 2-3-1.Tensile strength The tensile strength of the molded body was measured in accordance with JIS K 7161 by a tensile test.

[0079] 2-3-2.Fracture strain The fracture strain of the molded body was measured in accordance with JIS K 7161 in a tensile test.

[0080] 2-3-3. Elastic modulus The elastic modulus of the molded body was measured in accordance with JIS K 7161 based on a tensile test.

[0081] 2-4. Heat deflection temperature (HDT) The deflection temperature under load of the molded body was measured in accordance with JIS K 7191. The deflection temperature under load was measured by cutting a test piece (length 80 mm, width 10 mm, thickness 4 mm) from the molded body and using a heat destation tester under the conditions of a bending stress of 0.45 MPa applied to the test piece and a standard deflection of 0.34 mm.

[0082] 2-5. Charpy impact strength The Charpy impact strength of the molded body at 23° C. and −30° C. was measured in accordance with JIS K 7111. The Charpy impact strength was measured using a Charpy impact tester (IT manufactured by Toyo Seiki Seisaku-sho, Ltd.).

[0083] 2-6. Lightness (L* value) The lightness (L* value) of the molded product based on the L*a*b* color system was measured in accordance with JIS Z 8781-4. The lightness (L* value) was measured using an L*a*b* color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name: SD7000) with a D65 light source and a viewing angle of 10° using the specular exclusion (SCE) method. The lightness (L* value) was measured for a resin composition containing jet black carbon black (a composition containing the above resin raw material, zinc stearate, a phenolic antioxidant, a phosphorus-based antioxidant, and a weathering agent).

[0084] 3.Results The evaluation results are shown in Table 1-3. Comparative Example 1 contains only random polypropylene as a resin raw material, while Comparative Example 2 contains block polypropylene in addition to random polypropylene as a resin raw material. Therefore, the Charpy impact strength value at 23°C of the molded body of Comparative Example 2 is greater than that of Comparative Example 1.

[0085] In Comparative Example 3 and Examples 1 and 2, in addition to random polypropylene and block polypropylene, the resin raw materials contain styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), and ethylene-1-butene copolymer (EBR), respectively. Therefore, the Charpy impact strength values ​​of the molded articles at 23°C in Comparative Example 3 and Examples 1 and 2 are greater than those in Comparative Example 2.

[0086] Example 1 contains a styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS) as a resin raw material, and Example 2 contains an ethylene-1-butene copolymer (EBR) as a resin raw material, so the Charpy impact strength of the molded body at -30°C is higher than that of Comparative Example 3.

[0087] Like Example 2, Example 3 does not contain a styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS) but contains an ethylene-1-butene copolymer (EBR) as a resin raw material. Examples 4-7 gradually increase the content of styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS) compared to Example 3. In Examples 3-7, the Charpy impact strength values ​​of the molded articles at 23°C and -30°C increase as the content of styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS) increases.

[0088] Like Example 3, Example 8 does not contain a styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS) as a resin raw material, but does contain an ethylene-1-butene copolymer (EBR). Similarly to Examples 3-7, Examples 8-11 also show that the Charpy impact strength values ​​of the molded articles at 23°C and -30°C increase with an increase in the content of styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS). Furthermore, Examples 8-11 have an ethylene-1-butene copolymer (EBR) content that is 2.5 parts by mass greater than that of Examples 3-6. Therefore, the Charpy impact strength values ​​of the molded articles at 23°C and -30°C increase in Examples 8-11 compared to that of Examples 3-6.

[0089] Example 12 does not contain ethylene-1-butene copolymer (EBR) as a resin raw material, but contains styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS). Example 12 has a higher content of styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS) than the Comparative Example and other Examples, and the Charpy impact strength values ​​of the molded body at 23°C and -30°C are significantly higher than those of the Comparative Example and other Examples.

[0090] Examples 1-3 contain at least one of a styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS) and an ethylene-1-butene copolymer (EBR) as the resin raw material, but have tensile strength, fracture strain, elastic modulus, and deflection temperature under load that are comparable to those of Comparative Examples 1-4.

[0091] 4. Effects of the Example According to the above examples, low-temperature impact resistance could be imparted to the polypropylene-based resin composition while maintaining transparency / semi-transparency.

[0092] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible.

Claims

1. Polypropylene and one or more members selected from the group consisting of styrene-ethylene-ethylene-propylene-styrene block copolymers and ethylene-α-olefin copolymers having a melting point of 100°C or less; A resin composition comprising:

2. The resin composition according to claim 1, further comprising at least one selected from the group consisting of carbon black, organic dyes, and inorganic pigments.

3. 2. The resin composition according to claim 1, wherein the haze according to JIS K 7136 is 60% or more and 90% or less.

4. A molded article made from the resin composition according to any one of claims 1 to 3.

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