Polypropylene resin composition and foam molded product

Abstract

An embodiment of the present invention relates to a polypropylene-based resin composition, or a foam molded body comprising the polypropylene-based resin composition. The polypropylene-based resin composition is a polypropylene-based resin composition (X) that: contains 20-80 parts by mass of an impact polypropylene (A) satisfying requirements (a-1) and (a-2), 10-40 parts by mass of an ethylene-based elastomer (B) satisfying requirements (b-1) and (b-2), and 10-40 parts by mass of an inorganic filler (C), the filler being talc; and satisfies requirement (x-1). (a-1) Has an MFR of 60-300 g / 10 min, measured at 230°C at a load of 2.16 kg in compliance with ASTM D-1238; (a-2) Contains a propylene-ethylene copolymer identified as a decane soluble at 23°C, the propylene-ethylene copolymer having an intrinsic viscosity [η] of 4.1-10 dl / g; (b-1) Has an MFR of 0.5-30 g / 10 min, measured at 190°C at a load of 2.16 kg in compliance with ASTM D-1238; (b-2) Has a density from 0.85 g / cm3 to 0.875 g / cm3; (x-1) Has a content of a polypropylene component, which has a molecular weight of 106.5 or greater, of less than 0.05 mass% with respect to 100 mass% of the propylene resin composition (X).

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a polypropylene-based resin composition or a foam-molded article containing a polypropylene-based resin composition. [Background technology]

[0002] Polypropylene resins are widely used in various fields, including daily necessities, housing, home appliances, and automobile parts, due to their excellent moldability, balance of physical properties, recyclability, and cost performance. In fields such as automobile interior and exterior parts, foamed molded articles of polypropylene and the like are sometimes used to reduce weight. As an example of a composition that can be used to produce such foamed molded articles, Patent Document 1 discloses a polypropylene-based resin composition for foaming, which contains 40 to 95 mass% of at least one propylene polymer (A) selected from the group consisting of propylene homopolymer (A-1) and propylene-ethylene copolymer (A-2), 5 to 60 mass% of an ethylene-α-olefin copolymer (B) (where the total of (A) and (B) is 100 mass%), and a β-crystal nucleating agent. It also discloses that the polypropylene-based resin composition for foaming can provide foamed molded articles with reduced occurrence of streaky appearance defects known as silver streaks.

[0003] Core-back molding is sometimes used to produce foam molded articles. Regarding polypropylene-based resin compositions that can be used in core-back molding, Patent Document 2 discloses a linear polypropylene-based resin composition containing a strain-hardening linear propylene-ethylene block copolymer, which is composed of a linear propylene polymer portion and a linear ethylene-propylene random copolymer portion and has specific physical properties and a specific composition, including a melt flow rate (MFR) exceeding 60 g / 10 min (MFR: 230°C, 2.16 kg load), and a blowing agent. Patent Document 2 also discloses that the use of such a linear polypropylene-based resin composition has the effect of making bubbles at the flow front less likely to break, preventing the occurrence of irregularities on the foam molded article surface and enabling the provision of injection foam molded articles with excellent surface appearance.

[0004] Patent Document 3 discloses a polypropylene resin composition (X) for foam molding, which comprises a polypropylene resin composition (A) having a sea-island structure containing a polypropylene resin as a sea component and a thermoplastic resin as island components, and a blowing agent (B). Patent Document 3 exemplifies the polypropylene resin composition (A) as a propylene-ethylene block copolymer having an MFR (230°C, 2.16 kg load) of 50 to 300 g / 10 min. Patent Document 3 also discloses that the polypropylene resin composition (A) is formed so that the sea component and island component components have a specific specific interfacial area, thereby making it difficult for turbulence and bubble entrainment to occur at the melt front (the leading edge of the resin flow) and suppressing the formation of dimples on the surface of injection-molded foam. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-255191 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-144133 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-196398 Summary of the Invention

[0006] After extensive research, the present inventors have found that the composition described in Patent Document 1 has problems such as low impact resistance and a tendency to develop dimples (indentations). Although the formation of dimples is suppressed in molded articles using the compositions described in Patent Documents 2 and 3, the composition described in Patent Document 2 requires a linear propylene-ethylene block copolymer polypropylene component, which is strain-hardening, while the composition described in Patent Document 3 requires the polypropylene resin composition (A) to be formed so that the sea component and island component have a specific or greater specific interfacial area. Therefore, the compositions described in Patent Documents 2 and 3 are not versatile and cannot be easily produced. Furthermore, the compositions described in Patent Documents 2 and 3 have relatively high flow resistance, which may make them unsuitable for molding parts with long flow lengths.

[0007] Since foamed bodies have lower impact resistance than non-foamed bodies, there is a need for a resin composition that can be used to produce molded bodies with excellent impact resistance. Furthermore, in order to stably produce foamed bodies, there is a need for a resin composition that can be easily produced and that can suppress appearance defects such as flow marks, incomplete foaming, and dimples.

[0008] Therefore, one embodiment of the present invention provides a polypropylene-based resin composition that is less likely to cause appearance defects such as dimples, insufficient foaming, and flow marks on the surface of the molded article, is usable for producing molded articles with excellent impact properties, and can be produced relatively easily. [Means for solving the problem]

[0009] A configuration example of the present invention is as follows. In this specification, the numerical range "A to B" indicates A or more and B or less.

[0010] [1] 20 parts by mass or more and 80 parts by mass or less of impact polypropylene (A) that satisfies the following requirements (a-1) and (a-2); 10 parts by mass or more and 40 parts by mass or less of an ethylene-based elastomer (B) that satisfies the following requirements (b-1) and (b-2); containing 10 parts by mass or more and 40 parts by mass or less of an inorganic filler (C) which is talc (wherein the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is 100 parts by mass); A polypropylene resin composition (X) that satisfies the following requirement (x-1): (a-1) The MFR measured in accordance with ASTM D-1238 at 230°C under a load of 2.16 kg is 60 g / 10 min or more and 300 g / 10 min or less; (a-2) contains a propylene-ethylene copolymer identified as a decane-soluble portion at 23°C, and the intrinsic viscosity [η] of the propylene-ethylene copolymer measured in decalin at 135°C is 4.1 dl / g or more and 10 dl / g or less; (b-1) The MFR measured in accordance with ASTM D-1238 at 190°C under a load of 2.16 kg is 0.5 g / 10 min or more and 100 g / 10 min or less; (b-2) Density is 0.85 g / cm 3 More than 0.875g / cm 3 Below is; (x-1) A polypropylene resin composition (X) having a molecular weight of 10 6.5 The content of the above polypropylene components is less than 0.05% by mass.

[0011] [2] The polypropylene resin composition (X) according to [1], wherein the impact polypropylene (A) further satisfies at least one of the following requirements (a-1-1), (a-2-1), and (a-5): (a-1-1) The MFR measured in accordance with ASTM D-1238 at 230°C under a load of 2.16 kg is 77 g / 10 min or more and 200 g / 10 min or less; (a-2-1) The propylene-ethylene copolymer is identified as a decane-soluble portion at 23°C, and the intrinsic viscosity [η] of the propylene-ethylene copolymer measured in decalin at 135°C is 4.2 dl / g or more and 5.9 dl / g or less; (a-5) When the mass of the impact polypropylene (A) is taken as 100 mass%, the content of a propylene-ethylene copolymer, specified as a decane-soluble portion (Dsol) at 23°C, contained in the impact polypropylene (A) is 5 to 30 mass%.

[0012] [3] The polypropylene-based resin composition (X) according to [1] or [2], wherein the content of the propylene-ethylene copolymer in the polypropylene-based resin composition (X) is 5 parts by mass or more and 30 parts by mass or less (wherein the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is 100 parts by mass).

[0013] [4] The polypropylene resin composition (X) according to any one of [1] to [3], wherein the ethylene elastomer (B) is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms.

[0014] [5] The content of the impact polypropylene (A) is 25 parts by mass or more and 74 parts by mass or less, the content of the ethylene-based elastomer (B) is 10 parts by mass or more and 40 parts by mass or less, The polypropylene resin composition (X) according to any one of [1] to [4], wherein the content of the inorganic filler (C) is 16 parts by mass or more and 35 parts by mass or less (wherein the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is 100 parts by mass).

[0015] [6] A foam-molded article made of the polypropylene resin composition (X) according to any one of [1] to [5], which is molded using a foaming agent (D).

[0016] [7] An automobile interior / exterior part comprising the polypropylene resin composition (X) according to any one of [1] to [5].

[0017] [8] An arch molding comprising the polypropylene resin composition (X) according to any one of [1] to [5].

[0018] [9] A rocker molding comprising the polypropylene resin composition (X) according to any one of [1] to [5].

[0019]

[10] A method for producing a foamed molded article, comprising a step of foaming the polypropylene resin composition (X) according to any one of [1] to [5].

[0020]

[11] The method for producing a foamed molded article according to

[10] , which comprises injection foam molding or core-back injection molding. [Effects of the Invention]

[0021] According to one embodiment of the present invention, there is provided a polypropylene-based resin composition that is less likely to cause appearance defects such as dimples, insufficient foaming, and flow marks on the surface of a molded article, is usable for producing a molded article having excellent impact properties, and can be produced relatively easily. DETAILED DESCRIPTION OF THE INVENTION

[0022] <Polypropylene resin composition (X)> A polypropylene-based resin composition (X) according to one embodiment of the present invention (hereinafter also referred to as "resin composition (X)") contains an impact polypropylene (A) that satisfies predetermined requirements, an ethylene-based elastomer (B) that satisfies predetermined requirements, and may further contain an inorganic filler (C).

[0023] <Impact Polypropylene (A)> The impact polypropylene (A) used in the resin composition (X) satisfies the following requirements (a-1) and (a-2), and preferably further satisfies one or more of the following requirements (a-3) to (a-5):

[0024] [Requirement (a-1)] The melt flow rate (hereinafter also referred to as "MFR") measured in accordance with ASTM D-1238 at 230°C under a load of 2.16 kg is 60 to 300 g / 10 min, preferably 60 to 250 g / 10 min, more preferably 60 to 200 g / 10 min or less, still more preferably 70 to 180 g / 10 min, particularly preferably 77 to 160 g / 10 min, and especially preferably 90 to 155 g / 10 min. When the MFR of the impact polypropylene (A) is within the above range, the appearance of the molded article obtained from the resin composition (X) containing the impact polypropylene (A) is good, and the moldability and physical properties of the resin composition (X) are also good.

[0025] [Requirement (a-2)] The impact polypropylene (A) contains a propylene-ethylene copolymer specified as a decane-soluble fraction (Dsol) at 23°C, and the propylene-ethylene copolymer has an intrinsic viscosity (135°C, decalin) [η] of 4.1 to 10 dL / g, preferably 4.1 to 8.0 dL / g, more preferably 4.2 to 7.0 dL / g, and even more preferably 4.5 to 5.9 dL / g. When the intrinsic viscosity [η] of the propylene-ethylene copolymer is within the above range, the appearance of a molded article obtained from the resin composition (X) containing the impact polypropylene (A) is good, and the moldability of the resin composition (X) is also good.

[0026] [Requirement (a-3)] The impact polypropylene (A) preferably contains a propylene homopolymer specified as the decane insoluble fraction (Dinsol) at 23°C, and the MFR (230°C, 2.16 kg load) of the propylene homopolymer is preferably 200 to 800 g / 10 min, more preferably 250 to 600 g / 10 min, and even more preferably 310 to 550 g / 10 min. When the MFR of the propylene homopolymer is within the above range, the appearance of the molded article becomes good. The method for measuring the MFR of the propylene homopolymer is as described in the Examples below.

[0027] [Requirement (a-4)] For 100% by mass of impact polypropylene (A), the molecular weight of the impact polypropylene (A) is 10 6.5 The amount of the polypropylene component is preferably less than 0.05% by mass, more preferably less than 0.03% by mass, even more preferably less than 0.02% by mass, and particularly preferably less than 0.01% by mass. 6.5 The above polypropylene components may not be contained. Impact polypropylene (A) contains a molecular weight of 10 6.5 When the amount of the polypropylene component is within the above range, the occurrence of dimples can be effectively suppressed in the foamed molded article obtained from the resin composition (X) containing the impact polypropylene (A). 6.5 The amount of the polypropylene component can be adjusted, for example, by the type of catalyst used in producing the impact polypropylene (A). 6.5 The method for measuring the amount of the polypropylene component is as described in the Examples below.

[0028] [Requirement (a-5)] The content of the propylene-ethylene copolymer, specified as the decane-soluble fraction (Dsol) at 23°C contained in the impact polypropylene (A), is not particularly limited as long as it can be adjusted so that the content of the propylene-ethylene copolymer in the resin composition (X) falls within the range described below. Taking the mass of the impact polypropylene (A) as 100 mass%, the content is preferably 5 to 35 mass%, more preferably 9 to 30 mass%, and even more preferably 12 to 25 mass%. However, the sum of the decane-soluble fraction (Dsol) and the decane-insoluble fraction (Dinsol) is taken as 100 mass%. When the amount of the propylene-ethylene copolymer contained in the impact polypropylene (A) falls within the above range, the content of the propylene-ethylene copolymer in the resin composition (X) can be easily adjusted to the desired range.

[0029] The content of the impact polypropylene (A) in the resin composition (X) is 20 to 80 parts by mass (where the total amount of the impact polypropylene (A), ethylene-based elastomer (B), and inorganic filler (C) is 100 parts by mass), preferably 25 to 78 parts by mass, more preferably 30 to 78 parts by mass, even more preferably 40 to 76 parts by mass, particularly preferably 40 to 74 parts by mass, and especially preferably 45 to 68 parts by mass. When the content of the impact polypropylene (A) is within the above range, the appearance and physical properties of a molded article obtained from the resin composition (X) are good, and the moldability of the resin composition (X) is good.

[0030] The impact polypropylene (A) may be used singly or in combination of two or more. When two or more types are used, it is preferable that each of the impact polypropylenes (A) used satisfies the above requirements (a-1) to (a-2). When two or more types are used, the total amount of the impact polypropylenes (A) used is adjusted to satisfy the above content range.

[0031] The impact polypropylene (A) may contain at least one biomass-derived monomer. The biomass-derived monomer contained in the impact polypropylene (A) may be a biomass-derived α-olefin, such as biomass-derived ethylene or biomass-derived propylene. The same type of monomer constituting the polymer contained in the impact polypropylene (A) may contain only biomass-derived monomers, or may contain both biomass-derived monomers and fossil fuel-derived monomers. Note that biomass-derived α-olefins such as biomass-derived ethylene and biomass-derived propylene can be obtained by known methods. Here, the biomass-derived monomer is a monomer made from any renewable natural raw material or residue thereof, such as plant-derived or animal-derived raw material, including fungi, yeast, algae, and bacteria, and when the total carbon contained in the monomer is taken as 1, the following is obtained: 14 C isotope 10 -12In addition, biomass-derived monomers have a biomass carbon concentration (pMC, percent modern carbon) of about 100 (pMC) as measured in accordance with ASTM D 6866.

[0032] It is preferable that the impact polypropylene (A) contains a biomass-derived monomer from the viewpoint of reducing the environmental load. If the polymer production conditions such as the polymerization catalyst and polymerization temperature are the same, even if the raw material olefin contains a biomass-derived olefin, 14 C isotope is 10 of the total carbon -12 The molecular structure, other than the proportion of biomass-derived monomers, is the same as that of impact polypropylene (A) made from fossil fuel-derived monomers. Therefore, the performance of impact polypropylene (A) containing biomass-derived monomers is the same as that of impact polypropylene (A) made from fossil fuel-derived monomers.

[0033] The impact polypropylene (A) may contain a chemically recycled monomer. The monomer constituting the polymer may be a chemically recycled α-olefin, such as chemically recycled ethylene or chemically recycled propylene. The same type of monomers constituting the polymer contained in the impact polypropylene (A) may consist solely of chemically recycled monomers, or may contain chemically recycled monomers together with fossil fuel-derived monomers and / or biomass-derived monomers. Chemically recycled monomers can be obtained by conventional methods. It is preferable for the impact polypropylene (A) of the present invention to contain chemically recycled monomers from the perspective of reducing environmental impact (mainly waste reduction). Even if the raw material monomers contain chemically recycled monomers, the chemically recycled monomers are monomers obtained by depolymerizing or pyrolyzing polymers such as waste plastics back into monomer units such as propylene, or monomers produced using such monomers as raw materials. Therefore, if the polymer production conditions, such as the polymerization catalyst, polymerization process, and polymerization temperature, are equivalent, the molecular structure will be equivalent to that of impact polypropylene made from fossil fuel-derived monomers. Therefore, the performance is also expected to be unchanged.

[0034] <Ethylene-based elastomer (B)> The ethylene-based elastomer (B) used in the resin composition (X) satisfies the following requirements (b-1) and (b-2), and preferably further satisfies the following requirement (b-3).

[0035] [Requirement (b-1)] The MFR measured in accordance with ASTM D-1238 at 190°C under a load of 2.16 kg is 0.5 to 30 g / 10 min, preferably 0.9 to 30 g / 10 min, and more preferably 10 to 30 g / 10 min. If the MFR of the ethylene-based elastomer (B) exceeds 30 g / 10 min, the impact resistance tends to decrease. If the MFR of the ethylene-based elastomer (B) is within the above range, the moldability of the resin composition (X) containing the ethylene-based elastomer (B) is good, and the appearance and impact resistance of the molded article obtained from the resin composition (X) are good.

[0036] [Requirement (b-2)] The density of the ethylene elastomer (B) is 0.85 to 0.875 g / cm 3 and preferably 0.85 to 0.874 g / cm3 , more preferably 0.855 to 0.873 g / cm 3 The density is 0.85g / cm 3 If it is less than 0.875 g / cm, the foaming moldability may be poor. 3 If the density of the ethylene elastomer (B) is in the above range, the moldability and impact resistance of the resulting molded article will be good.

[0037] [Requirement (b-3)] The ethylene-based elastomer (B) is preferably a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms. Specific examples of the α-olefin having 3 to 10 carbon atoms copolymerizable with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, and 1-decene. Two or more of these α-olefins may be used in combination. Of these, 1-butene and 1-octene are particularly preferred because they result in good impact resistance of the resulting molded article.

[0038] The content of the ethylene-based elastomer (B) in the resin composition (X) is 10 to 40 parts by mass (where the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is 100 parts by mass), preferably 10 to 35 parts by mass, more preferably 10 to 30 parts by mass, and even more preferably 16 to 30 parts by mass. When the content of the ethylene-based elastomer (B) is within the above range, the moldability of the resin composition (X) is good, and the appearance and impact resistance of a molded article obtained from the resin composition (X) are good.

[0039] The ethylene-based elastomer (B) may be used alone or in combination of two or more. When two or more types are used, it is preferable that each of the ethylene-based elastomers (B) used satisfies the above requirements (b-1) and (b-2). When two or more types are used, the total amount of the ethylene-based elastomers (B) used is adjusted to satisfy the above content range.

[0040] <Inorganic filler (C)> Examples of inorganic fillers (C) that can be used in one embodiment of the present invention include, but are not limited to, heavy calcium carbonate, light calcium carbonate, talc, Wollastonite, Mos-Hige®, carbon fiber, glass fiber, magnesium carbonate, mica, kaolin, calcium sulfate, barium sulfate, titanium white, white carbon, carbon black; metal oxides such as aluminum oxide, magnesium oxide, silicon oxide, and zinc oxide; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; metal nitrides such as boron nitride and aluminum nitride; metal oxynitrides such as aluminum oxynitride; metal carbides such as silicon carbide; metals or metal alloys such as gold, silver, copper, and aluminum; natural graphite, artificial graphite, and expanded graphite. These fillers can be used alone or in combination. Among these, talc is most preferred. The shape of the talc is not particularly limited, but talc having a D50 (μm) of usually 0.5 to 20 μm, preferably 1.0 to 15 μm in the number-based particle size distribution measured by a laser diffraction scattering method is suitably used.

[0041] The content of the inorganic filler (C) in the resin composition (X) is 10 to 40 parts by mass (where the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is 100 parts by mass), preferably 12 to 35 parts by mass, more preferably 14 to 30 parts by mass, and even more preferably 16 to 25 parts by mass. When the content of the inorganic filler (C) is within the above range, the molded article formed from the resin composition (X) has a good balance between the flexural modulus and impact resistance.

[0042] <Other ingredients> The resin composition (X) may contain various additives as needed, provided that the object of the present invention is not impaired. Specific examples of the additives include nucleating agents, antioxidants, hydrochloric acid absorbers, heat stabilizers, weather stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, flame retardants, pigments, dyes, dispersants, copper inhibitors, neutralizing agents, plasticizers, crosslinking agents, flow improvers (e.g., peroxides), weld strength improvers, natural oils, synthetic oils, and waxes.

[0043] <Resin composition (X)> The resin composition (X) satisfies the following requirement (x-1), and preferably further satisfies the following requirement (x-2).

[0044] [Requirements (x-1)] The molecular weight of the resin composition (X) is 10 6.5 The amount of the polypropylene component is less than 0.05% by mass, preferably less than 0.03% by mass, and more preferably less than 0.01% by mass. 6.5 The above polypropylene components may not be contained. The molecular weight of the resin composition (X) is 10 6.5 When the amount of the polypropylene component is within the above range, the occurrence of dimples in the foamed molded article obtained from the resin composition (X) can be effectively suppressed. 6.5 The amount of the polypropylene component is, for example, 6.5 This can be adjusted by using impact polypropylene (A) having a low content of polypropylene components. 6.5 The method for measuring the amount of the polypropylene component is as described in the Examples below.

[0045] [Requirements (x-2)] The content of the propylene-ethylene copolymer in the resin composition (X), specified as the decane-soluble portion (Dsol) at 23°C, is preferably 1 to 30 parts by mass (where the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is taken as 100 parts by mass), more preferably 3 to 30 parts by mass, and even more preferably 5 to 30 parts by mass. The content of the propylene-ethylene copolymer is a value obtained by the method described in the Examples. When the content of the propylene-ethylene copolymer is within the above range, the resin composition (X) has excellent moldability, and molded articles obtained from the resin composition (X) have good appearance and impact resistance.

[0046] <Method for producing resin composition (X)> The resin composition (X) can be produced by melt-kneading the impact polypropylene (A), the ethylene-based elastomer (B), the inorganic filler (C), and, if necessary, the other additives, using a conventionally known mixing device such as a kneader.

[0047] <Foam molded body> A foam-molded article according to one embodiment of the present invention is produced using resin composition (X). That is, a foam-molded article according to one embodiment of the present invention is obtained by adding a blowing agent (D) to resin composition (X) and molding the mixture.

[0048] The foaming agent (D) used in producing the foamed molded article according to one embodiment of the present invention is not particularly limited, and any known chemical foaming agent or physical foaming agent can be used. The amount of foaming agent (D) added is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 8 parts by mass, per 100 parts by mass of resin composition (X).

[0049] The chemical foaming agent may be an inorganic compound or an organic compound, and two or more types may be used. Inorganic compounds used as chemical foaming agents include bicarbonates such as sodium bicarbonate. Organic compounds used as chemical foaming agents include polycarboxylic acids such as citric acid and azo compounds such as azodicarbonamide (ADCA). Examples of physical foaming agents include inert gases such as nitrogen and carbon dioxide, and volatile organic compounds. Among these, it is preferable to use carbon dioxide or nitrogen in a supercritical state, or a mixture thereof. Two or more types of physical foaming agents may be used in combination, or a chemical foaming agent and a physical foaming agent may be used in combination.

[0050] When a physical foaming agent is used, it is preferable to bring the physical foaming agent to a supercritical state and mix it with the molten resin composition (X). The physical foaming agent in the supercritical state has high solubility in resin and can be uniformly diffused into the molten polypropylene resin composition in a short time, thereby making it possible to obtain a foamed molded article with a high expansion ratio and a uniform foam cell structure. The step of mixing the physical foaming agent with the molten polypropylene resin composition includes a step of injecting the physical foaming agent into the nozzle or cylinder of an injection molding machine.

[0051] Specific examples of the method for foam molding the resin composition (X) include known methods such as injection foam molding, press foam molding, extrusion foam molding, and stampable foam molding.

[0052] The foam molded article according to one embodiment of the present invention can also be made into a decorated foam molded article by laminating a skin material onto the surface of the foam molded article by insert molding, adhesion or other methods.

[0053] The mold used for injection foam molding is preferably composed of, for example, a fixed mold and a movable mold, which are preferably in a clamped state when the resin composition (X) is injected and filled. The volume of the cavity can be increased by retracting the movable mold (core-back) to expand the cavity. The volume of the cavity is preferably increased after an appropriate time has elapsed since injection and filling. The core movement speed during core-back can be determined appropriately depending on the thickness of the molded article, the type of resin, the type of foaming agent, the mold temperature, and the resin temperature.

[0054] The temperature of the resin composition (X) and the mold temperature when the resin composition (X) is injection molded will vary depending on conditions such as the thickness of the molded article to be produced, but temperatures typically used for molding polypropylene resins can be applied. Specifically, for example, the temperature of the resin composition (X) when injected is typically 180 to 250°C, preferably 200 to 220°C. The surface temperatures of the fixed mold and the movable mold are typically 10 to 100°C, preferably 30 to 80°C.

[0055] In the foam-molded article obtained by foam-molding resin composition (X), the balance between the viscosity of the polypropylene component and the viscosity of the ethylene-based elastomer is adjusted, so that the surface of the molded article formed from resin composition (X) is less susceptible to appearance defects such as dimples, incomplete foaming, and flow marks. Furthermore, when resin composition (X) is filled into a cavity, pressure changes at the flow front of resin composition (X) (the leading edge of the flow of molten resin composition (X)) are small, so pulsation and meandering of the flow front are less likely to occur. Therefore, it is presumed that the generation of bubbles due to pressure changes and differences in the orientation of the ethylene-based elastomer are reduced, making dimples and incomplete foaming less likely to occur, and flow marks are less likely to occur.

[0056] Molded articles produced from resin composition (X) can be suitably used for various applications, such as automobile interior and exterior parts, substitutes for cardboard, electrical appliances, building materials, etc. Examples of automobile interior and exterior parts include arch moldings, rocker moldings, side sill protectors, and back doors, with arch moldings and rocker moldings being preferred. [Example]

[0057] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0058] <Ingredients> The raw materials used in the following examples and comparative examples are as follows.

[0059] [Impact Polypropylene (A)] Impact Polypropylene (A-1): MFR (230°C, 2.16 kg load) = 97 g / 10 min, percentage of decane solubles at room temperature = 14.3 mass%, intrinsic viscosity [η] of decane solubles at room temperature = 5.0 dl / g Impact Polypropylene (A-2): MFR (230°C, 2.16 kg load) = 144 g / 10 min, percentage of decane solubles at room temperature = 13.4 mass%, intrinsic viscosity [η] of decane solubles at room temperature = 4.8 dl / g Impact Polypropylene (A-3): MFR (230°C, 2.16 kg load) = 128 g / 10 min, percentage of decane solubles at room temperature = 14.3 mass%, intrinsic viscosity [η] of decane solubles at room temperature = 5.0 dl / g Impact Polypropylene (A-4): MFR (230°C, 2.16 kg load) = 79 g / 10 min, percentage of decane solubles at room temperature = 12.9 mass%, intrinsic viscosity [η] of decane solubles at room temperature = 4.4 dl / g In both the impact polypropylene (A) and the impact polypropylene (CA) described below, the room temperature decane soluble portion is the decane soluble portion at 23°C.

[0060] [Impact polypropylene (CA) used in the comparative example] Impact Polypropylene (CA-1): MFR (230°C, 2.16 kg load) = 129 g / 10 min, percentage of decane solubles at room temperature = 14.4 mass%, intrinsic viscosity [η] of decane solubles at room temperature = 2.7 dl / g Impact Polypropylene (CA-2): MFR (230°C, 2.16 kg load) = 107 g / 10 min, percentage of decane solubles at room temperature = 15.9 mass%, intrinsic viscosity [η] of decane solubles at room temperature = 3.3 dl / g Impact Polypropylene (CA-3): MFR (230°C, 2.16 kg load) = 56 g / 10 min, percentage of decane solubles at room temperature = 12.2 mass%, intrinsic viscosity [η] of decane solubles at room temperature = 4.9 dl / g

[0061] [Ethylene-based elastomer (B)] Ethylene-based elastomer (B-1): Ethylene-1-octene copolymer (EOR), manufactured by The Dow Chemical Company, ENGAGE® 8137, MFR (190°C, 2.16 kg load) = 13 g / 10 min, density = 0.864 g / cm 3 Ethylene-based elastomer (B-2): Ethylene-1-octene copolymer (EOR), manufactured by The Dow Chemical Company, ENGAGE® 8100, MFR (190°C, 2.16 kg load) = 1.0 g / 10 min, density = 0.870 g / cm 3 Ethylene-based elastomer (B-3): Ethylene-1-octene copolymer (EOR), manufactured by The Dow Chemical Company, ENGAGE® 8407, MFR (190°C, 2.16 kg load) = 30 g / 10 min, density = 0.870 g / cm 3

[0062] [Ethylene-based elastomer (CB) used in comparative examples] Ethylene-based elastomer (CB-1): Ethylene-1-butene copolymer (EBR), LG Chem LF675, MFR (190°C, 2.16 kg load) = 14 g / 10 min, density = 0.877 g / cm 3 Ethylene-based elastomer (CB-2): Ethylene-1-butene copolymer (EBR), Toughmer (registered trademark) A-35050S manufactured by Mitsui Chemicals, Inc., MFR (190°C, 2.16 kg load) = 35 g / 10 min, density = 0.863 g / cm 3 Ethylene-based elastomer (CB-3): Ethylene-1-butene copolymer (EBR), Toughmer (registered trademark) A-35070S manufactured by Mitsui Chemicals, Inc., MFR (190°C, 2.16 kg load) = 35 g / 10 min, density = 0.870 g / cm 3

[0063] [Inorganic filler (C)] "Inorganic filler (C-1)": Talc (manufactured by Asada Flour Milling Co., Ltd., product name JM-209, D50 (laser diffraction) in particle size distribution based on number of particles: 4 to 5 μm

[0064] [Blowing agent (D)] "Masterbatch of organic blowing agent (D-1)": Masterbatch containing 10-20% by mass of ADCA (azodicarbonamide), manufactured by Eiwa Kasei Co., Ltd., Polythrene EE206

[0065] [Additives] Nucleating agent: Phosphate ester metal salt nucleating agent, manufactured by ADEKA Corporation, ADK STAB NA-11 (sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate)

[0066] The composition and physical properties of each component used in the examples and comparative examples were measured by the following methods.

[0067] <Content of n-decane solubles at 23°C> A glass measuring vessel was charged with 2.0000 g of impact polypropylene (A-1), 500 ml of decane, and a small amount of a decane-soluble heat stabilizer. Under a nitrogen atmosphere, the mixture was heated to 150°C over 2 hours while stirring with a stirrer to dissolve the impact polypropylene (A-1). The mixture was then held at 150°C for 2 hours and then slowly cooled to 23°C over 8 hours. After slowly cooling, the sample was filtered under reduced pressure through a glass filter. 100 ml of the filtrate was collected and dried under reduced pressure to obtain a portion of the decane-soluble fraction, which was then weighed. The proportion of the n-decane-soluble fraction (Dsol) was determined using the following formula: In the following formula, a is the mass of the decane-soluble component obtained by the vacuum drying process, and b is the mass of the impact polypropylene (A-1) placed in the measuring vessel. Ratio of n-decane solubles (Dsol) (mass%) =(500×a) / (100×b)×100 Furthermore, the amount of propylene-ethylene copolymer in the composition containing impact polypropylene (A-1) was calculated as the product of the amount of impact polypropylene (A-1) and the proportion of n-decane solubles. For the other impact polypropylenes, the proportion of n-decane solubles at 23°C was determined in the same manner as for impact polypropylene (A-1), and the obtained values ​​were used to calculate the content (parts by mass) of propylene-ethylene copolymer in each composition of the Examples and Comparative Examples.

[0068] <Intrinsic viscosity [η]> The intrinsic viscosity [η] of propylene-ethylene copolymers, identified as the n-decane soluble fraction (Dsol), was measured in decalin at 135°C according to a conventional method. Specifically, approximately 20 mg of the decane soluble fraction obtained by the vacuum drying process used to determine the n-decane soluble fraction at 23°C was dissolved in 15 ml of decalin, and the specific viscosity [ηsp] was measured in an oil bath at 135°C. This decalin solution was diluted with 5 ml of decalin solvent, and the specific viscosity [ηsp] was then measured in the same manner. This dilution procedure was repeated two more times, and the value of [ηsp] / [C] when the concentration (C) was extrapolated to 0 was used to calculate the intrinsic viscosity [η]. [η]=lim(ηsp / C) (C→0)

[0069] <Melt flow rate (MFR)> The MFR of the impact polypropylenes (A-1) to (A-4) and the impact polypropylenes (CA-1) to (CA-3) was measured in accordance with ASTM D-1238 at 230°C and a load of 2.16 kg. The MFR of the ethylene-based elastomers (B-1) to (B-3) and the ethylene-based elastomers (CB-1) to (CB-3) was measured in accordance with ASTM D-1238 under conditions of 190°C and a load of 2.16 kg.

[0070] The MFR of the propylene homopolymer contained in the impact polypropylenes (A-1) to (A-4) and the impact polypropylenes (CA-1) to (CA-3) was measured after separating the propylene homopolymer from the impact polypropylene by the following separation process. The MFR of the propylene homopolymer was measured in accordance with ASTM D-1238 at 230°C under a load of 2.16 kg.

[0071] (Propylene homopolymer separation treatment) A glass measuring vessel was charged with 2.0000 g of impact polypropylene (A-1), 500 ml of decane, and a small amount of a heat-resistant stabilizer soluble in decane. The mixture was heated to 150°C over 2 hours under a nitrogen atmosphere while stirring with a stirrer to dissolve the impact polypropylene (A). The mixture was then maintained at 150°C for 2 hours and then filtered under reduced pressure through a glass filter. The residue remaining on the glass filter was taken as the n-decane-insoluble portion (Dinsol), i.e., the propylene homopolymer in the impact polypropylene (A-1). For the impact polypropylenes (A-2) to (A-4) and the impact polypropylenes (CA-1) to (CA-3), the propylene homopolymer was separated by the same treatment as for the impact polypropylene (A-1).

[0072] [Example 1] <Preparation of Resin Composition (X1)> 61 parts by weight of impact polypropylene (A-1), 18.5 parts by weight of ethylene-based elastomer (B-1), and 20.5 parts by weight of inorganic filler (C-1) were mixed to obtain a resin composition (X1). The resin composition (X1) was then granulated to obtain pellets of the resin composition (X1).

[0073] <Measurement of the content of high molecular weight polypropylene components> Molecular weight of resin composition (X1) 10 6.5 The content of the above polypropylene components was determined by measuring the molecular weight distribution of the measurement sample by gel permeation chromatography (GPC) under the following measurement conditions, and then subtracting 10% from the integrated molecular weight distribution value. 6.5 The amount of the component consisting of homopolypropylene having the above molecular weight was calculated. ·GPC measurement device Column: TOSO GMHHR-H(S)HT (2 pieces) Detector: RI detector for liquid chromatography WATERS 150C Measurement conditions Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145℃ Flow rate: 1.0ml / min Sample concentration: 5mg / 10ml Injection volume: 300μl Calibration curve: Universal Calibration Analysis program: HT-GPC (Ver. 1.0)

[0074] <Impact resistance evaluation> Pellets of the resin composition (X1) were molded to prepare a non-foamed molded body, and test specimens (with notches) were prepared from the obtained non-foamed molded body in accordance with ISO 179. The obtained test specimens were subjected to a Charpy impact test at 23°C in accordance with ISO 179. Furthermore, the obtained Charpy impact values ​​were evaluated according to the following impact resistance evaluation criteria.

[0075] (Impact resistance evaluation standard) ○: Charpy impact value is 30 kJ / m 2 exceed ×: Charpy impact value is 30 kJ / m 2 below

[0076] <Injection foam molding> Two parts by mass of a masterbatch of an organic blowing agent (D-1) was blended with 100 parts by mass of pellets of the resin composition (X1). The values ​​in the column for organic blowing agent (D-1) in Table 1 below are the amounts of the organic blowing agent (D-1) calculated assuming that the masterbatch of the organic blowing agent (D-1) contains 20% by mass of ADCA. After thoroughly mixing the pellets and the masterbatch of the organic blowing agent (D-1), injection foam molding was carried out using an injection molding machine (J350ADS-460H model (clamping force 3440 kN) manufactured by The Japan Steel Works, Ltd.) under the following conditions:

[0077] <Injection foam molding conditions> ·Molds Cavity size: length 350mm, width 100mm, thickness 2.0mm Gate: Side gate thickness 1mm, width 6mm Cylinder temperature setting: Eight thermocouple temperatures are set to 190°C, 190°C, 205°C, 205°C, 190°C, 180°C, 160°C, and 50°C, starting from the nozzle head side. Mold surface temperature: 40℃ Injection speed: 80mm / s Foam molding conditions Injection mold cavity clearance: 2.0 mm Mold clearance after foaming process: 3.0 mm Core back setting time: 0.05 seconds Core back delay time after resin filling: 0 seconds

[0078] <Appearance evaluation of injection molded products> [Flow mark evaluation] The core-back surface of the foamed molded article obtained by the injection foam molding method was visually inspected for the presence of flow marks (continuous changes in gloss). The inspection results were evaluated according to the following criteria. (Flow mark evaluation criteria) ◯: No flow marks were observed between the gate position and a position 100 mm from the gate. ×: Flow marks occurred between the gate position and a position 100 mm from the gate.

[0079] [Dimple evaluation] The presence or absence of dimples was visually confirmed between the gate position and a position 100 mm from the gate, and the confirmation results were evaluated according to the following evaluation criteria. (Dimple evaluation criteria) ◯: No visually visible dimples were generated between the gate position and a position 100 mm from the gate. ×: Visually visible dimples are present between the gate position and a position 100 mm from the gate.

[0080] [Evaluation of foaming defects] The molded product was visually inspected for foaming defects (large dents) at a position 100 mm from the end. The results are shown in Table 1. (Evaluation criteria for foaming defects) ○: No depression of 10 mm or more has occurred between the end of the molded product and a position 100 mm from the end ×: A depression of 10 mm or more has occurred between the end of the molded product and a position 100 mm from the end.

[0081] [Examples 2 to 4, Comparative Examples 1 to 6] Resin compositions used in the Examples and Comparative Examples were prepared using the types and amounts of raw materials shown in Tables 1 and 2, and the resulting resin compositions were used in place of resin composition (X1) to produce samples for impact resistance evaluation and foam molded articles. Impact resistance evaluation and foam molded article evaluation were performed in the same manner as in Example 1. The obtained results are shown in Tables 1 and 2.

[0082] [Table 1]

[0083] [Table 2]

[0084] As shown in Table 1, the foamed molded articles obtained in all of Examples 1 to 4 had excellent impact resistance. Furthermore, no flow marks or dimples were observed on the surface of the foamed molded articles, and no depressions of 10 mm or larger occurred. This result is presumably due to the fact that in Examples 1 to 4, the polypropylene component and the ethylene-based elastomer component contained in the resin composition (X) used for molding had a good viscosity balance, which reduced pressure changes at the flow front (the leading edge of the flow of the molten resin composition (X)) and prevented pulsation and meandering of the flow front. In other words, when resin composition (X) was used, the pressure changes at the flow front were small, which presumably prevented the generation of bubbles due to pressure changes. Furthermore, the good viscosity balance between the polypropylene component and the ethylene-based elastomer component in resin composition (X) resulted in a relatively small difference in orientation of the ethylene-based elastomer at the flow front, which presumably prevented the generation of dimples, poor foaming, and flow marks. Furthermore, it is speculated that the resin composition (X) has a favorable viscosity ratio between the polypropylene component and the ethylene-based elastomer component, which results in good dispersion of the ethylene-based elastomer, and as a result, the foamed molded article obtained from the resin composition (X) has excellent impact resistance.

[0085] On the other hand, Comparative Examples 1 and 2 had poor impact resistance and flow mark evaluation results due to the low intrinsic viscosity of the propylene-ethylene copolymer component contained in the impact polypropylene. Comparative Example 3 had poor impact resistance due to the high density of the ethylene-based elastomer (CB-1) and poor dispersibility of the ethylene-based elastomer (CB-1). Comparative Examples 4 and 5 had poor impact resistance and also suffered from poor foaming due to the high MFR of the ethylene-based elastomer. Comparative Example 6 had a low MFR of the impact polypropylene, which tended to cause disruption of the flow front, resulting in the formation of dimples on the surface of the molded product and poor foaming.

Claims

1. 20 parts by mass or more and 80 parts by mass or less of impact polypropylene (A) satisfying the following requirements (a-1) and (a-2); 10 parts by mass or more and 40 parts by mass or less of an ethylene-based elastomer (B) that satisfies the following requirements (b-1) and (b-2); containing 10 parts by mass or more and 40 parts by mass or less of an inorganic filler (C) which is talc (where the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is 100 parts by mass); A foamed molded article obtained by molding a polypropylene resin composition (X) that satisfies the following requirement (x-1) using a foaming agent (D). (a-1) The MFR measured in accordance with ASTM D-1238 at 230°C under a load of 2.16 kg is 60 g / 10 min or more and 300 g / 10 min or less; (a-2) contains a propylene-ethylene copolymer specified as a decane-soluble portion at 23°C, and the intrinsic viscosity [η] of the propylene-ethylene copolymer measured in decalin at 135°C is 4.1 dl / g or more and 10 dl / g or less; (b-1) The MFR measured in accordance with ASTM D-1238 at 190°C under a load of 2.16 kg is 0.5 g / 10 min or more and 30 g / 10 min or less; (b-2) Density is 0.85 g / cm 3 Above, 0.875g / cm 3 The following is true: (x-1) A polypropylene resin having a molecular weight of 10 6.5 The content of the above polypropylene component is less than 0.05% by mass.

2. The foam-molded article according to claim 1, wherein the impact polypropylene (A) further satisfies at least one of the following requirements (a-1-1), (a-2-1) and (a-5): (a-1-1) The MFR measured in accordance with ASTM D-1238 at 230°C under a load of 2.16 kg is 77 g / 10 min or more and 200 g / 10 min or less; (a-2-1) The propylene-ethylene copolymer is specified as a decane-soluble portion at 23°C, and the intrinsic viscosity [η] of the propylene-ethylene copolymer measured in decalin at 135°C is 4.2 dl / g or more and 5.9 dl / g or less; (a-5) When the mass of the impact polypropylene (A) is taken as 100 mass%, the content of a propylene-ethylene copolymer contained in the impact polypropylene (A), which is specified as a decane-soluble fraction (Dsol) at 23°C, is 5 to 30 mass%.

3. 2. The foam molded article according to claim 1, wherein the content of the propylene-ethylene copolymer in the polypropylene-based resin composition (X) is 5 parts by mass or more and 30 parts by mass or less (wherein the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is 100 parts by mass).

4. 2. The foam-molded article according to claim 1, wherein the ethylene-based elastomer (B) is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms.

5. The content of the impact polypropylene (A) is 25 parts by mass or more and 74 parts by mass or less, the content of the ethylene-based elastomer (B) is 10 parts by mass or more and 40 parts by mass or less, 2. The foamed molded article according to claim 1, wherein the content of the inorganic filler (C) is 16 parts by mass or more and 35 parts by mass or less (wherein the total amount of the impact polypropylene (A), the ethylene-based elastomer (B), and the inorganic filler (C) is 100 parts by mass).

6. An automobile interior or exterior part comprising the foam molded article according to any one of claims 1 to 5.

7. An arch molding comprising the foam molded article according to any one of claims 1 to 5.

8. A rocker molding comprising the foam molded article according to any one of claims 1 to 5.

9. A method for producing a foamed molded article according to claim 1, comprising a step of foaming the polypropylene resin composition (X).

10. The method for producing a foamed molded article according to claim 9, wherein injection foam molding or core-back injection molding is carried out.

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