Thermoplastic elastomer composition

Abstract

A thermoplastic elastomer composition that is obtained by crosslinking a composition which contains an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A), a propylene-based polymer (B) having a melt flow rate (MFR (B)) of 5-25 g / 10 minutes as measured at 230°C under a load of 2.16 kg in accordance with JIS K7210-1, and an olefin resin (C) other than the propylene-based polymer (B), wherein: the content of the propylene-based polymer (B) is 20-100 parts by mass with respect to 100 parts by mass of the component (A); and the ratio (MFR (B) / MFR (C)) of the MFR (B) to the melt flow rate (MFR (C)) of the olefin resin (C) as measured at 230°C under a load of 2.16 kg in accordance with JIS K7210-1 is 5-500.

Description

Thermoplastic elastomer composition

[0001] The present invention relates to a thermoplastic elastomer composition.

[0002] Olefin-based thermoplastic elastomers are lightweight, easy to recycle, and do not generate toxic gases when incinerated. For these reasons, from the viewpoints of energy saving and resource saving, and in recent years, from the viewpoint of protecting the global environment, olefin-based thermoplastic elastomers are widely used especially as alternatives to vulcanized rubber in automotive parts, industrial machinery parts, electrical and electronic parts, building materials and the like.

[0003] As a novel dynamically crosslinked thermoplastic elastomer composition that has low hardness, excellent compression set, and good appearance when formed into a molded article, for example, Patent Document 1 discloses a dynamically crosslinked thermoplastic elastomer composition comprising the following components (A) to (D), wherein the content of component (A) is 70 to 90 parts by mass and the content of component (B) is 10 to 30 parts by mass based on 100 parts by mass of the total of component (A) and component (B), the content of component (C) is 0.05 to 20 parts by mass and the content of component (D) is 20 to 200 parts by mass relative to 100 parts by mass of the total of component (A) and component (B), and the durometer A hardness according to JIS K6253 is 60 or lower. Component (A): Ethylene / α-olefin / non-conjugated diene copolymer rubber Component (B): Modified polypropylene exhibiting strain hardening, having a melt flow rate of 0.1 to 250 g / 10 minutes (at 230°C, 21.2 N load, in accordance with JIS K7210) and a melt tension of 1.0 to 20 cN Component (C): Crosslinking agent Component (D): Softening agent for hydrocarbon-based rubbers

[0004] Further, as a novel thermoplastic elastomer composition excellent in mechanical strength and compression set, for example, Patent Document 2 discloses a dynamically crosslinked thermoplastic elastomer composition comprising the following component (A), component (B), component (C) and component (D). Component (A): Ethylene / α-olefin / non-conjugated diene copolymer rubber Component (B): Modified polypropylene exhibiting strain hardening Component (C): Crosslinking agent Component (D): Softening agent for hydrocarbon-based rubbers

[0005] Japanese Patent Publication No. 2019-44111 Japanese Patent Publication No. 2018-154707

[0006] The thermoplastic elastomer compositions described in Patent Documents 1 and 2 do not address the balance between appearance and foaming properties during foam molding, and further improvements are needed. The problem that one embodiment of the present invention aims to solve is to provide a thermoplastic elastomer composition that yields a foamed molded article that is highly foamable and has a good appearance even when foamed.

[0007] The means for solving the above problems include the following embodiments: <1> A rubber comprising an ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), a propylene polymer (B) having a melt flow rate (MFR(B)) of 5 to 25 g / 10 min measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1, and an olefin resin (C) other than the propylene polymer (B), wherein the content of the propylene polymer (B) is 20 to 100 parts by mass per 100 parts by mass of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), and the olefin resin (B) has a melt flow rate (MFR(C)) of 5 to 25 g / 10 min measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1. A thermoplastic elastomer composition obtained by crosslinking a composition in which the ratio of melt flow rates (MFR(B) / MFR(C)) measured at 230°C and a 2.16 kg load in accordance with K7210-1 is 5 to 500. <2> The thermoplastic elastomer composition according to <1>, wherein the melt flow rate (MFR(C)) of the olefin resin (C), measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1, is 0.01 g / 10 min or more and less than 5 g / 10 min. <3> The thermoplastic elastomer composition according to <1> or <2>, wherein the propylene polymer (B) is a polypropylene homopolymer or a propylene-ethylene copolymer. <4> The thermoplastic elastomer composition according to any one of <1> to <3>, wherein the intrinsic viscosity [η] of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), measured in decalin at 135°C, is 4 dl / g or more. <5> The thermoplastic elastomer composition according to any one of <1> to <4>, wherein the oil spreading amount per 100 parts by mass of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A) is 50 to 200 parts by mass. <6> The thermoplastic elastomer composition according to any one of <1> to <5>, further comprising a crosslinking agent (D), wherein the crosslinking agent (D) is a phenolic resin. <7> The thermoplastic elastomer composition according to any one of <1> to <6>, further comprising a crosslinking agent (D), wherein the crosslinking agent (D) is an organic peroxide.<8> The thermoplastic elastomer composition according to any one of <1> to <7>, wherein the composition further comprises a plasticizer (E). <9> The thermoplastic elastomer composition according to <8>, wherein the content of the plasticizer (E) is 50 to 300 parts by mass per 100 parts by mass of ethylene-α-olefin-non-conjugated polyene copolymer rubber (A). <10> The thermoplastic elastomer composition according to any one of <1> to <9>, wherein the content ratio of the olefin resin (C) to the total content of the propylene polymer (B) and the olefin resin (C) is 7 to 70% by mass. <11> A molded article formed using the thermoplastic elastomer composition according to any one of <1> to <10>. <12> The molded article according to <11>, wherein the foaming ratio of the foamed article is 1.5 times or more. <13> The molded article according to <11> or <12>, which is an automobile part. <14> A molded body according to any one of <11> to <13>, which is a sealing member for an automobile door.

[0008] According to one embodiment of the present invention, a thermoplastic elastomer composition is provided that yields a foamed molded article that exhibits excellent foaming properties and has a good appearance even when foamed.

[0009] The present invention will be described in detail below. The explanation of the constituent elements described below may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification and in the claims, "parts by mass" refers to parts by mass on a solid content basis, excluding solvents. Also, a numerical range represented by "~" means a numerical range with the numbers before and after "~" as the lower and upper limits, respectively. In this specification, units described either before or after "~" indicating a numerical range mean the same unit unless otherwise specified. Also, in this specification, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the multiple substances present in the composition. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, unless otherwise specified, each component in a composition, or each constituent unit in a polymer, may be included alone or in combination of two or more types. In the present invention, polymer means both homopolymers and copolymers unless otherwise specified. Furthermore, the various monomers in this invention may be derived from fossil raw materials, from biological sources such as biomass, or from mixtures thereof.

[0010] [Thermoplastic Elastomer Composition] The thermoplastic elastomer composition according to the present invention comprises an ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), a propylene polymer (B) having a melt flow rate (MFR(B)) of 5 to 25 g / 10 min measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1, and an olefin resin (C) other than the propylene polymer (B), wherein the content of the propylene polymer (B) is 20 to 100 parts by mass per 100 parts by mass of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), and the JIS The thermoplastic elastomer composition is obtained by crosslinking a composition (hereinafter sometimes referred to as "uncrosslinked composition") in which the ratio (MFR(B) / MFR(C)) of the melt flow rate (MFR(B)) measured at 230°C and a 2.16 kg load in accordance with K7210-1 is 5 to 500. The thermoplastic elastomer composition having the above configuration yields a foamed molded article with excellent foaming properties and a good appearance even when foamed. The reason for this is not clear, but the following mechanism is suspected. The thermoplastic elastomer composition uses two polymers with different fluidities, and the (MFR(B) / MFR(C)) ratio is within a specific range, thereby maintaining high foaming properties and preventing foam collapse during foaming. When the thermoplastic elastomer composition according to the present invention is foamed, the propylene polymer (B) becomes the main foaming phase. On the other hand, when a composition with a single resin phase is used for foaming, there is a tendency for foam collapse to occur as foaming progresses. In this invention, by including an olefin resin (C) with a higher molecular weight and viscosity than the propylene polymer (B) in the composition together with the propylene polymer (B), it is hypothesized that when the composition is foam-molded, the olefin resin (C) acts as a protective barrier for the bubbles during bubble growth, preventing bubble bursting. Furthermore, in this invention, by setting the MFR ratio of the propylene polymer (B) to the olefin resin (C) (MFR(B) / MFR(C)) in the range of 5 to 500, it is possible to achieve both foaming properties and bubble maintenance.

[0011] (Uncrosslinked Composition) The uncrosslinked composition comprises an ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), a propylene polymer (B) having a melt flow rate (MFR(B)) of 5 to 25 g / 10 min measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1, and an olefin resin (C) other than the propylene polymer (B). The components contained in the uncrosslinked composition will be described in detail below.

[0012] [Ethylene-α-olefin-non-conjugated polyene copolymer (A)] In the uncrosslinked composition, the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A) (hereinafter sometimes simply referred to as "polymer rubber (A)") may be at least partially crosslinked, or it may be an uncrosslinked copolymer rubber (A). From the viewpoint of ease of manufacturing the thermoplastic elastomer composition, it is preferable that the copolymer rubber (A) is uncrosslinked.

[0013] Examples of α-olefins constituting the copolymer rubber (A) include α-olefins having 3 to 20 carbon atoms. Specifically, examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene. Among these, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene are preferred as α-olefins having 3 to 20 carbon atoms, with propylene being particularly preferred. α-olefins may be used individually or in combination of two or more types.

[0014] Examples of non-conjugated polyenes constituting the copolymer rubber (A) include chain-like non-conjugated dienes such as 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 7-methyl-1,6-octadiene, 8-methyl-4-ethylidene-1,7-nonadiene, and 4-ethylidene-1,7-undecadiene; Examples include methyltetrahydroindene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 5-vinyl-2-norbornene, 5-isopropenyl-2-norbornene, 5-isobutenyl-2-norbornene, cyclopentadiene, norbornadiene, and other cyclic non-conjugated dienes; and trienes such as 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, and 4-ethylidene-8-methyl-1,7-nanodiene. Non-conjugated polyenes may be used individually or in combination of two or more. Among these non-conjugated polyenes, non-conjugated dienes are preferred, and 5-ethylidene-2-norbornene (ENB) or 5-vinyl-2-norbornene (VNB) are more preferred.

[0015] The copolymer rubber (A) contains ethylene-derived structural units, preferably 50 to 90% by mass, more preferably 50 to 85% by mass, even more preferably 50 to 75% by mass, and particularly preferably 50 to 70% by mass, based on 100% by mass of the total structural units derived from ethylene, α-olefins, and non-conjugated polyenes. The content of α-olefin-derived structural units is preferably 9.5 to 49.5% by mass, more preferably 14.5 to 49.5% by mass, and even more preferably 24.5 to 49.5% by mass, based on 100% by mass of the total structural units derived from ethylene, α-olefins, and non-conjugated polyenes. The content of constituent units derived from non-conjugated polyene (C) is preferably 0.07 to 10% by mass, more preferably 0.1 to 8.0% by mass, and even more preferably 0.5 to 5.0% by mass, based on 100% by mass of the total of constituent units derived from ethylene, α-olefin, and non-conjugated polyene. The content (by mass%) of constituent units derived from ethylene, α-olefin, and non-conjugated polyene in copolymer rubber (A) is: １３ This is determined by C-NMR.

[0016] The copolymer rubber (A) has an intrinsic viscosity [η] measured in decalin at 135°C, preferably 4 dl / g or more, more preferably in the range of 4 to 10 dl / g, even more preferably in the range of 4 to 8 dl / g, and particularly preferably in the range of 4 to 6 dl / g.

[0017] The copolymer rubber (A) may be a so-called oil-expandable rubber, which is manufactured by blending a softener, preferably a mineral oil-based softener, with it. There are no particular restrictions on the mineral oil-based softener used for oil expansion, and examples include conventionally known mineral oil-based softeners, such as paraffinic process oils. The amount of oil expansion (i.e., the content of mineral oil-based softener contained in the copolymer rubber (A)) per 100 parts by mass of copolymer rubber (A) is preferably 50 parts by mass or more, more preferably 50 to 200 parts by mass, even more preferably 60 to 180 parts by mass, particularly preferably 65 to 160 parts by mass, and most preferably 70 to 130 parts by mass. An oil expansion amount of 50 parts by mass or more is advantageous when performing foam molding because it reduces the content of plasticizer (E) in the uncrosslinked composition and suppresses the decrease in viscosity of the propylene polymer (B) which becomes the foam phase. The oil-expandable rubber may be prepared by mixing a softener and copolymer rubber (A), or it may be a commercially available product. The oil spreadability is determined by extracting copolymer rubber (A) with acetone or methyl ethyl ketone, concentrating the filtrate, and measuring the amount of softener contained in copolymer rubber (A). If a catalog value for oil spreadability is available, the catalog value may be used.

[0018] The content of copolymer rubber (A) is preferably 40 to 90 parts by mass, more preferably 50 to 80 parts by mass, and even more preferably 60 to 70 parts by mass, based on 100 parts by mass of the total amount of copolymer rubber (A), propylene polymer (B) described later, and olefin polymer (C) described later. When the content of copolymer rubber (A) is within the above range, excellent heat resistance is achieved, and surface roughness of the resulting foamed molded article can be suppressed. Copolymer rubber (A) may be used alone or in combination of two or more types.

[0019] There are no particular restrictions on the method for producing the copolymer rubber (A), and conventionally known methods can be used. Furthermore, commercially available copolymer rubber (A) may also be used.

[0020] [Propylene-based polymer (B)] A propylene-based polymer (B) (hereinafter also simply referred to as "propylene-based polymer (B)") having a melt flow rate (MFR(B)) of 5 to 25 g / 10 min measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1 is not particularly limited as long as the above MFR(B) is 5 to 25 g / 10 min. It may be a propylene homopolymer or a high molecular weight solid product obtained by polymerizing propylene with at least one α-olefin other than propylene by a high-pressure or low-pressure method (i.e., a copolymer of propylene and an α-olefin other than propylene). The propylene-based polymer (B) may be a random copolymer or a block copolymer.

[0021] Examples of α-olefins other than propylene include α-olefins having 2 or 4 to 20 carbon atoms. Examples of α-olefins having 2 or 4 to 20 carbon atoms include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene. These propylene-based polymers may be used individually or in combination of two or more types.

[0022] The propylene polymer (B) is preferably a propylene polymer having a content of 40 mol% or more of structural units derived from propylene, and more preferably a propylene polymer having a content of 50 mol% or more of structural units derived from propylene.

[0023] The propylene polymer (B) is preferably a propylene homopolymer or a copolymer of propylene and an α-olefin having 2 or 4 to 20 carbon atoms, more preferably a propylene homopolymer, a propylene-ethylene copolymer, or a propylene-ethylene-butene copolymer, and even more preferably a propylene-ethylene block copolymer, a propylene-ethylene random copolymer, or a propylene-ethylene-butene random copolymer. The stereostructure of the propylene polymer (B) may be an isotactic structure, a syndiotactic structure, a mixture of these structures, or may include a partially atactic structure.

[0024] The propylene polymer (B) has a melt flow rate (MFR(B)) of 5 to 25 g / 10 min, preferably 5 to 20 g / 10 min, and more preferably 7 to 17 g / 10 min, as measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1. When the melt flow rate (MFR(B)) of the propylene polymer (B) is within the above range, bubbles grow easily during foaming and bubble bursting can be suppressed, resulting in excellent foaming properties. The melt flow rate (MFR(B)) of the propylene polymer (B) can be adjusted to the range of 5 to 25 g / 10 min by adjusting the molecular weight and distribution of the propylene polymer (B).

[0025] The melting point of the propylene polymer (B) is typically in the range of 80 to 200°C, preferably 120 to 170°C, and more preferably 145 to 165°C.

[0026] There are no particular restrictions on the method for producing the propylene polymer (B), and various known polymerization methods can be used. Furthermore, commercially available propylene polymers (B) may also be used.

[0027] The content of the propylene polymer (B) is 20 to 100 parts by mass, preferably 25 to 60 parts by mass, more preferably 25 to 50 parts by mass, and most preferably 30 to 45 parts by mass, per 100 parts by mass of the copolymer rubber (A) described above. A content of 20 to 100 parts by mass of propylene polymer (B) per 100 parts by mass of copolymer rubber (A) is preferable because it provides a good balance between hardness and foaming properties. The propylene polymer (B) may be used alone or in combination of two or more types.

[0028] [Olefin resin (C)] The olefin resin (C) is a resin other than the propylene polymer (B). There are no particular restrictions on the olefin resin (C) as long as it is a resin other than the propylene polymer (B). For example, it may be a homopolymer of α-olefins, or an α-olefin copolymer composed of two or more types of α-olefins. Examples of α-olefins include α-olefins having 2 to 20 carbon atoms. Examples of α-olefins having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene, etc. The olefin resin (C) may be a random copolymer or a block copolymer. The olefin resin (C) is preferably an α-olefin homopolymer, more preferably an α-olefin homopolymer having 2 to 5 carbon atoms, and even more preferably a high-density polyethylene and propylene homopolymer.

[0029] The olefin resin (C) preferably has a melt flow rate (MFR(C)) of 0.01 g / 10 min or more and less than 5 g / 10 min, more preferably 0.01 to 4 g / 10 min, and even more preferably 0.03 to 3 g / 10 min, measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1. When the melt flow rate (MFR(C)) of the olefin resin (C) is within the above range, bubbles grow easily during foaming, and bubble bursting is suppressed, resulting in excellent foaming properties and a good appearance for the resulting foamed molded article.

[0030] There are no particular restrictions on the method for producing the olefin resin (C), and various known polymerization methods can be used. Commercially available olefin resins (C) may also be used.

[0031] The content of the olefin resin (C) is preferably 3 to 30 parts by mass, more preferably 4 to 20 parts by mass, even more preferably 4 to 15 parts by mass, and particularly preferably 4 to 10 parts by mass, per 100 parts by mass of the copolymer rubber (A). When the content of the propylene polymer (C) is within the above range, the foaming properties are excellent, and the appearance of the resulting foamed molded article is good. The olefin resin (C) may be used alone or in combination of two or more types.

[0032] The content ratio of the olefin resin (C) to the total content of the propylene polymer (B) and the olefin resin (C) is preferably 7 to 70% by mass, more preferably 10 to 60% by mass, and even more preferably 15 to 45% by mass. When the content ratio of the olefin resin (C) is within the above range, it is easier for the olefin resin (C) to retain bubbles, improving foaming properties and suppressing surface roughness during foam molding.

[0033] The content ratio of the propylene polymer (B) to the total content of the propylene polymer (B) and the olefin resin (C) is preferably 30 to 90% by mass, more preferably 40 to 90% by mass, and even more preferably 50 to 90% by mass.

[0034] <(MFR(B) / MFR(C))> The ratio (MFR(B) / MFR(C)) of the melt flow rate (MFR(C)) of the olefin resin (C), measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1, to the melt flow rate (MFR(B)) of the propylene polymer (B), measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1, is 5 to 500, preferably 10 to 400, more preferably 10 to 350, and even more preferably 15 to 250. When the (MFR(B) / MFR(C)) ratio is between 5 and 500, the propylene polymer (B) contains olefin resin (C) which has a lower MFR and higher molecular weight than the propylene polymer (B). The polymer chains of component (C) act as walls during bubble growth in foam molding, suppressing bubble breakage and improving the foaming ratio, resulting in excellent foaming properties. In addition, the appearance of the resulting foamed molded article is good.

[0035] [Crosslinking agent (D)] The uncrosslinked composition preferably further contains a crosslinking agent (D). The crosslinking agent (D) is preferably a phenolic resin or an organic peroxide.

[0036] <<Phenolic Resins>> Examples of phenolic resins include those produced by the condensation of substituted or unsubstituted phenols with an aldehyde, preferably formaldehyde, or by the condensation of difunctional phenol dialcohols. Substituted phenols are preferably alkyl-substituted compounds having 1 to 10 carbon atoms. Halogenated phenolic resins can also be suitably used as phenolic resins.

[0037] For phenolic resins, refer to the descriptions in U.S. Patents No. 3,287,440, No. 3,709,840, and No. 4,311,628.

[0038] As the phenolic resin, commercially available phenolic resins can be appropriately selected and used. Examples of commercially available phenolic resins that can be used include Tackyrol 201 (alkylphenol formaldehyde resin, manufactured by Taoka Chemical Industry Co., Ltd.), Tackyrol 250-I (brominated alkylphenol formaldehyde resin with a bromination rate of 4%, manufactured by Taoka Chemical Industry Co., Ltd.), Tackyrol 250-III (brominated alkylphenol formaldehyde resin, manufactured by Taoka Chemical Industry Co., Ltd.), PR-4507 (manufactured by Gun-ei Chemical Industry Co., Ltd.), Vulkaresat 510E (manufactured by Hoechst), Vulkaresat 532E (manufactured by Hoechst), Vulkaresen E (manufactured by Hoechst), Vulkaresen 105E (manufactured by Hoechst), Vulkaresen 130E (manufactured by Hoechst), and Vulkaresol 315E (manufactured by Hoechst), Amberol ST 137X (manufactured by Rohm & Haas), Sumilight Resin PR-22193 (manufactured by Sumitomo Durez Co., Ltd.), Symphorm-C-100 (manufactured by Anchor Chem.), Symphorm-C-1001 (manufactured by Anchor Chem.), Tamanol 531 (manufactured by Arakawa Chemical Corporation), Schenectady SP1059 (manufactured by Schenectady Chem.), Schenectady SP1045 (manufactured by Schenectady Chem.), CRR-0803 (manufactured by U.C.C.), Schenectady Examples include SP-1055F (manufactured by Schenectady Chem.), Schenectady SP-1056 (manufactured by Schenectady Chem.), CRM-0803 (manufactured by Showa Union Synthetic Co., Ltd.), and Vulkadur A (manufactured by Bayer). Among these, brominated alkylphenol formaldehyde resin is preferred as the phenolic resin.

[0039] Phenolic resins are typically used with activators. Examples of activators include halogen donors such as stannous chloride, ferric chloride, chlorinated paraffin, chlorinated polyethylene, and chlorosulfonated polyethylene, and acid acceptors such as iron oxide, titanium oxide, magnesium oxide, silicon dioxide, and zinc oxide. If the phenolic resin is halogenated, a halogen donor may not be necessary.

[0040] The phenolic resin content is preferably 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 1 to 8 parts by mass, per 100 parts by mass of copolymer rubber (A). When the phenolic resin content is within the above range, a composition with excellent moldability is obtained, and the resulting molded article has high strength, excellent oil resistance, and sufficient heat resistance and mechanical properties. The phenolic resin may be used alone or in combination of two or more types.

[0041] The amount of halogen donor added is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of copolymer rubber (A). The amount of acid acceptor added is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, per 100 parts by mass of copolymer rubber (A).

[0042] <<Organic Peroxides>> Organic peroxides can be aromatic or aliphatic, and may be a single peroxide or a mixture of two or more peroxides. Specifically, dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyn-3, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane; t-butylperoxybenzoate, t-butylperoxybenzoate Examples include peroxyesters such as xyisopropyl monocarbonate, n-butyl-4,4-bis(t-butylperoxy)valerate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexyn-3; and diacyl peroxides such as diacetyl peroxide, lauroyl peroxide, dibenzoyl peroxide, p-chlorobenzoyl peroxide, and 2,4-dichlorobenzoyl peroxide. Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane or 1,3-bis(t-butylperoxyisopropyl)benzene are particularly preferred as organic peroxides.

[0043] Organic peroxides are preferably those with a half-life temperature of 140°C to 230°C. Organic peroxides that satisfy this condition include dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyn-3, 1,3-bis(t-butylperoxyisopropyl)benzene, and 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane; t-butylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, n-butyl-4,4-bis(t-butylperoxy)valerate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexyn-3.

[0044] The content of the organic peroxide in the uncrosslinked composition is preferably 0.5 to 1.5 parts by mass, more preferably 0.7 to 1.4 parts by mass, and still more preferably 0.9 to 1.3 parts by mass, relative to 100 parts by mass of the copolymer rubber (A). The organic peroxide may be used alone, or two or more kinds thereof may be used in combination.

[0045] From the viewpoint of homogenizing the crosslinking reaction, the uncrosslinked composition may further contain a crosslinking aid together with the organic peroxide. Specific examples of the crosslinking aid include divinyl compounds such as divinylbenzene; oxime compounds such as p-quinone dioxime and p,p'-dibenzoylquinone dioxime; nitroso compounds such as N-methyl-N-4-dinitrosoaniline and nitrosobenzene; maleimide compounds such as trimethylolpropane-N,N'-m-phenylene dimaleimide; and also sulfur, diphenylguanidine, triallyl cyanurate and the like. Other examples of the crosslinking aid include polyfunctional methacrylate monomers such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate and allyl methacrylate; and polyfunctional vinyl monomers such as vinyl butyrate and vinyl stearate. Among these, divinyl compounds such as divinylbenzene are preferable as the crosslinking aid.

[0046] The content of the crosslinking aid is preferably 0.05 to 1.5 parts by mass, more preferably 0.1 to 1 part by mass, relative to 100 parts by mass of the copolymer rubber (A). The crosslinking aid may be used alone, or two or more kinds thereof may be used in combination.

[0047] [Plasticizer (E)] From the viewpoint of softening the resulting thermoplastic elastomer composition, increasing flexibility and elasticity, and improving the processability and fluidity of the uncrosslinked composition, the uncrosslinked composition may further contain a plasticizer (E). There are no particular limitations on the plasticizer (E), and examples include plasticizers generally used in rubbers. Examples of the plasticizer (E) include mineral oil hydrocarbons such as paraffin-based, naphthene-based, and aromatic-based hydrocarbons; low-molecular-weight hydrocarbons such as polybutene-based and polybutadiene-based hydrocarbons; and glycerin. Among these, mineral oil hydrocarbons are preferable as the plasticizer (E). Generally, mineral oil hydrocarbons include mixtures of aromatic hydrocarbons, naphthene-based hydrocarbons, and paraffin-based hydrocarbons. Those in which the proportion of carbons derived from aromatic hydrocarbons relative to the total carbon content is 35% by mass or more are called aromatic oils, those in which the proportion of carbons derived from naphthene-based hydrocarbons is 30 to 45% by mass are called naphthene oils, and those in which the proportion of carbons derived from paraffin-based hydrocarbons is 50% by mass or more are called paraffin oils. Among these, paraffin oil is preferable as the plasticizer (E). As the plasticizer (E), an oil-extended rubber obtained by preliminarily mixing (oil-extending) the copolymer rubber (A) with a plasticizer may be used as the plasticizer (E). Further, the plasticizer (E) may be used when preparing the uncrosslinked composition, or may be added post-hoc when dynamically heat-treating each component contained in the uncrosslinked composition.

[0048] The content of the plasticizer (E) is preferably 50 to 300 parts by mass, more preferably 100 to 280 parts by mass, and still more preferably 150 to 250 parts by mass, per 100 parts by mass of the copolymer rubber (A). The plasticizer (E) may be used alone or in combination of two or more kinds thereof.

[0049] [Other Components] The uncrosslinked composition may contain components other than the copolymer rubber (A), propylene polymer (B), olefin resin (C), phenol resin or organic peroxide crosslinking agent (D), and crosslinking aid (hereinafter also referred to as "other components"). Examples of other components include conventionally known resins other than copolymer rubber (A), propylene polymer (B), and olefin resin (C) (for example, peroxide non-crosslinked rubber-like substances). Peroxide non-crosslinked rubber-like substances refer to hydrocarbon-based rubber-like substances that do not crosslink and do not experience a decrease in fluidity even when mixed with a peroxide and kneaded under heating, such as butyl rubber, polyisobutylene, atactic polypropylene, and propylene-α-olefin copolymer rubber with a propylene content of 50 mol% or more. The content of the peroxide non-crosslinked rubber-like substance is usually 25 parts by mass or less, preferably 20 parts by mass or less, and more preferably 1 to 15 parts by mass per 100 parts by mass of copolymer rubber (A).

[0050] Other components include, for example, conventionally known inorganic fillers, reinforcing materials, heat stabilizers (processing heat stabilizers), anti-aging agents, weather stabilizers, antistatic agents, nucleating agents, colorants, and lubricants. The total amount of inorganic fillers, reinforcing materials, heat stabilizers (processing heat stabilizers), anti-aging agents, weather stabilizers, antistatic agents, nucleating agents, colorants, and lubricants is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less, per 100 parts by mass of copolymer rubber (A).

[0051] Examples of the lubricant include higher fatty acid amides, metal soaps, waxes, silicone oils, and fluorinated polymers. Among these, higher fatty acid amides, silicone oils, and fluorinated polymers are preferred.

[0052] Examples of higher fatty acid amides include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behemic acid amide; unsaturated fatty acid amides such as erucic acid amide, oleic acid amide, brassic acid amide, and elaidic acid amide; and bis-fatty acid amides such as methylenebisstearate amide, methylenebisoleic acid amide, ethylenebisstearate amide, and ethylenebisoleic acid amide.

[0053] Examples of silicone oils include dimethyl silicone oil, phenylmethyl silicone oil, alkyl silicone oil, fluorosilicone oil, tetramethyltetraphenyltrisiloxane, and modified silicone oil.

[0054] Examples of fluorine-based polymers include polytetrafluoroethylene and vinylidene fluoride copolymers.

[0055] Examples of the inorganic fillers include calcium carbonate, calcium silicate, clay, kaolin, talc, silica, diatomaceous earth, mica powder, asbestos, alumina, barium sulfate, aluminum sulfate, calcium sulfate, basic magnesium carbonate, molybdenum disulfide, graphite, glass fiber, glass spheres, shirasu balloons, basic magnesium sulfate whiskers, calcium titanate whiskers, aluminum borate whiskers, and the like.

[0056] [Thermoplastic Elastomer Composition] The thermoplastic elastomer composition is obtained by crosslinking the above-mentioned uncrosslinked composition, preferably by dynamically crosslinking the uncrosslinked composition. That is, the thermoplastic elastomer composition is a crosslinked product. There are no particular restrictions on the shape of the thermoplastic elastomer composition, and it can be set as appropriate depending on the purpose. Examples of shapes of the thermoplastic elastomer composition include cylindrical, spherical, and ellipsoidal shapes. The thermoplastic elastomer composition may also be pellets obtained by melting composition raw materials such as polyene copolymer (A) to form strands and cutting the strands into granular shapes.

[0057] [Method for Producing Thermoplastic Elastomer Composition] There are no particular limitations on the method for producing the thermoplastic elastomer composition. For example, the copolymer rubber (A), the propylene polymer (B), the olefin resin (C), and optionally the softener (E) may be mixed, and then the crosslinking agent (D) may be added to the mixture to obtain an uncrosslinked composition which is then dynamically heat-treated. Alternatively, the copolymer rubber (A), the propylene polymer (B), the olefin resin (C), the crosslinking agent (D), and optionally the softener (E) may be mixed together to obtain an uncrosslinked composition which is then dynamically heat-treated. In this specification, "dynamically heat-treated" means melt-kneading the uncrosslinked composition under shear force. By the dynamic heat treatment described above, a thermoplastic elastomer composition is obtained in which at least a portion of the copolymer rubber (A) is crosslinked. The method for supplying components such as the copolymer rubber (A) to the kneading apparatus can be appropriately set depending on the apparatus used.

[0058] The kneading equipment used for dynamic heat treatment is not particularly limited as long as it can apply a high shear force. Examples of kneading equipment capable of applying a high shear force include mixing rolls, intensive mixers (e.g., Banbury mixers, Brabender mixers, kneaders, etc.), and single-screw or twin-screw extruders. Among these, dynamic heat treatment is preferably performed using a twin-screw extruder.

[0059] Dynamic heat treatment is preferably carried out in a closed-type apparatus, and more preferably in an inert gas atmosphere such as nitrogen or carbon dioxide.

[0060] The resin temperature during kneading in the dynamic heat treatment is preferably between the melting temperature of the olefin resin (C) and 250°C, more preferably 240°C or lower, and even more preferably 230°C or lower. The set temperatures for the extruder cylinder are, for example, preferably 50 to 150°C at the beginning of the cylinder, 150 to 250°C at the end, and 180 to 250°C for the die.

[0061] The thermoplastic elastomer composition preferably has a Type A hardness (instantaneous value) of 30 or higher, more preferably 40 to 98, even more preferably 50 to 80, and particularly preferably 55 to 70, in accordance with JIS K6253.

[0062] [Foaming agent] The thermoplastic elastomer composition may further contain a foaming agent. Examples of foaming agents include inorganic or organic pyrolysis-type foaming agents (chemical foaming agents), carbon dioxide, nitrogen, and mixtures of carbon dioxide and nitrogen. Examples of inorganic pyrolysis-type foaming agents include inorganic carbonates such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, and ammonium carbonate, and nitrites such as ammonium nitrite.

[0063] Examples of organic pyrolysis-type blowing agents include nitroso compounds such as N,N'-dimethyl-N,N'-dinitrosotelephthalamide and N,N'-dinitrosopentamethylenetetramine; azo compounds such as azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene, and barium azodicarboxylate; sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, p,p'-oxybis(benzenesulfonyl hydrazide), and diphenylsulfon-3,3'-disulfonyl hydrazide; azide compounds such as calcium azide, 4,4'-diphenyldisulfonyl azide, and p-toluenesulfonyl azide; and thermally expandable microcapsules (for example, product name: ADVANCEL EM, manufactured by Sekisui Chemical Co., Ltd.).

[0064] When using carbon dioxide or nitrogen, the composition used for foam molding is melted in a resin plasticizing cylinder at 100 to 300°C, forming a molten, foamed thermoplastic elastomer composition in which the composition used for foam molding and the carbon dioxide or nitrogen are in a miscible state.

[0065] The foaming agent content is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the thermoplastic elastomer composition.

[0066] Furthermore, the thermoplastic elastomer composition may contain a foaming agent as needed. The foaming agent content is usually 0.01 to 10 parts by mass, preferably 0.02 to 5 parts by mass, per 100 parts by mass of the thermoplastic elastomer composition. The foaming agent may be used alone or in combination of two or more types.

[0067] Examples of foaming agents include metal compounds such as zinc, calcium, lead, iron, and barium; higher fatty acids such as stearic acid and their metal salts; and fine inorganic particles such as talc, barium sulfate, and silica. Specifically, examples include mixtures of polycarboxylic acids such as citric acid, oxalic acid, fumaric acid, phthalic acid, malic acid, tartaric acid, cyclohexane-1,2-dicarboxylic acid, camphoric acid, ethylenediaminetetraacetic acid, triethylenetetraminehexaacetic acid, and nitrilotriacetic acid with inorganic carbonate compounds such as sodium bicarbonate, sodium aluminum bicarbonate, and potassium bicarbonate, as well as intermediates produced by these reactions, such as salts of polycarboxylic acids like sodium dihydrogen citrate and potassium oxalate.

[0068] If the thermoplastic elastomer composition contains a foaming agent, a foamed molded article can be obtained using the thermoplastic elastomer composition (preferably by extrusion molding).

[0069] There are no particular restrictions on the order in which the foaming agent and the foaming aid described later are added. For example, they may be dry-blended with the thermoplastic elastomer composition before molding (preferably extrusion molding), or the foaming agent and / or foaming aid may be allowed to decompose during molding (preferably extrusion molding), or they may be melt-blended with the pellets of the thermoplastic elastomer composition beforehand and then added.

[0070] The foaming ratio of the foamed molded article is preferably 1.5 times or more, and more preferably 2.0 times or more. The upper limit of the foaming ratio of the foamed molded article is not particularly limited, and is, for example, 30 times or less.

[0071] [Method for molding foamed molded articles] There are no particular limitations on the method for obtaining foamed molded articles using thermoplastic elastomer compositions, and known general processing methods (molding methods) for rubber compounding can be used. Specifically, these are as follows, but are not limited to the following conditions. As a method for molding foamed molded articles, for example, a foaming agent and, if necessary, a foaming aid can be added to the thermoplastic elastomer composition obtained by the above-mentioned method for producing thermoplastic elastomer compositions, and the article can be molded into a desired shape using various molding methods such as an extrusion molding machine, calender roll, press, injection molding machine, or transfer molding machine.

[0072] The foamed molded body can be suitably used in applications such as high-foaming sealants, automotive sealants, civil engineering and construction sealants, and various industrial sealants. It is particularly suitable for weatherstrip sponge materials (preferably with a foaming ratio of 1.3 to 4.0 times), and also for high-foaming sponge materials used in sponges, dam rubber, etc. (preferably with a foaming ratio exceeding 3.0 times and not exceeding 30 times).

[0073] [Molded Article] The molded article according to the present invention is formed using the thermoplastic elastomer composition described above. From the viewpoint of obtaining a foamed molded article with a good appearance even when foamed, it is also a preferred embodiment that the molded article is a foamed molded article.

[0074] The thermoplastic elastomer composition, which is a crosslinked body obtained in this way, and the molded articles formed using this composition have excellent surface appearance and can be used for automotive interior and exterior materials such as flooring, ceiling materials, instrument panels, door trims, and interior seats, as well as leisure seats, gaskets, waterproof sheets, bags, notebook covers, diary covers, belts, etc. In particular, the thermoplastic elastomer composition and the molded articles formed using this composition are ideal as automotive interior surface materials, such as surface materials for automotive instrument panels and automotive door trims. Among these, the molded articles can be suitably used as automotive parts or sealing members for automotive doors.

[0075] Next, the present invention will be described in detail based on examples, but the present invention is not limited to these examples. Various physical properties were measured by the following methods.

[0076] [Shore A Hardness] Using a 100t electric automatic press (manufactured by Shoji Co., Ltd.), the obtained thermoplastic elastomer composition pellets were press-molded at 230°C for 6 minutes, and then cooled and pressed at room temperature for 5 minutes to produce a 3 mm thick press sheet. Using this sheet, a Type A measuring instrument was used in accordance with JIS K6253, and the scale was read immediately after contact with the indenter.

[0077] [Melt Flow Rate (MFR)] The MFR of the (co)polymers used in the following examples and comparative examples was measured at 230°C and a 2.16 kg load, in accordance with JIS K7210-1.

[0078] [Intrinsic Viscosity] The intrinsic viscosity [η] of ethylene-α-olefin-non-conjugated polyene copolymer (A) was measured at 135°C using decalin solvent.

[0079] [Oil Spreading Volume] The oil spreading volume was determined by extracting copolymer rubber (A), described later, with acetone or methyl ethyl ketone, and concentrating the filtrate to measure the amount of softener contained in copolymer rubber (A).

[0080] <Ethylene-α-olefin-non-conjugated polyene copolymer (A)> ・EPDM-1: Product name "5469C", manufactured by ARLANXEO, ethylene content = 58% by mass, 5-ethylidene-2-norbornene (ENB) content = 4.5% by mass, intrinsic viscosity [η] = 5.7 dl / g, oil spread = 100 (PHR: Per hundred rubber) ・EPDM-2: Product name "V3666", manufactured by ExxonMobil, ethylene content = 64% by mass, 5-ethylidene-2-norbornene (ENB) content = 4.5% by mass, intrinsic viscosity [η] = 4.5 dl / g, oil spread = 75 (PHR) ・EPDM-3: Product name "X-3042E", manufactured by Mitsui Chemicals, Inc., ethylene content = 66% by mass , 5-ethylidene-2-norbornene (ENB) content = 4.7% by mass, intrinsic viscosity [η] = 4.0 dl / g, oil spread rate = 120 (PHR) Note that the above PHR indicates the oil content ratio per 100 parts by mass of non-oil-spread rubber. For example, in EPDM-1, "oil spread rate = 100 (PHR: Per hundred rubber)" means that the mineral oil-based softener contained in copolymer (A) is 100 parts by mass per 100 parts by mass of copolymer (A).

[0081] <Propylene-based polymers (B)> ・PP-1: Homopolypropylene (Product name: P701J, manufactured by SCG Chemicals, MFR (230℃, 2.16 kg load): 12 g / 10 min) ・PP-2: Block polypropylene (propylene-ethylene block copolymer) (Product name: J707G, manufactured by Prime Polymer Co., Ltd., MFR (230℃, 2.16 kg load): 30 g / 10 min) ・PP-3: Homopolypropylene (Product name: S119, manufactured by Prime Polymer Co., Ltd., MFR (230℃, 2.16 kg load): 60 g / 10 min) ・PP-4: Homopolypropylene (Product name: J106G, manufactured by Prime Polymer Co., Ltd., MFR (230℃, 2.16 kg load): 15 g / 10 min) PP-5: Homopolypropylene (Product name: P607F, manufactured by SCG Chemicals, MFR (230°C, 2.16 kg load): 7 g / 10 min)

[0082] <Olefin Resin (C)> ・PP-6: Homopolypropylene (Product name: E111G, manufactured by Prime Polymer Co., Ltd., MFR (230℃, 2.16kg load): 0.5g / 10min) ・PP-7: Homopolypropylene (Product name: E200GP, manufactured by Prime Polymer Co., Ltd., MFR (230℃, 2.16kg load): 2g / 10min) ・PE-1: High-density polyethylene (Product name: 7700M, manufactured by Prime Polymer Co., Ltd., MFR (230℃, 2.16kg load): 0.05g / 10min)

[0083] <Crosslinking agent (D)> ・Phenolic resin: Brominated alkylphenol formaldehyde resin (Model number: SP-1055F, manufactured by SI Group) ・Organic peroxide: 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane (Perhexa 25B, manufactured by NOF Corporation)

[0084] <Crosslinking aids> ・Zinc oxide (two types of zinc oxide, manufactured by Hakusui Tech Co., Ltd.) ・Divinylbenzene (product name "DVB-810", manufactured by Nippon Steel Chemical Co., Ltd.)

[0085] <Plasticizer (E)> - Paraffin-based process oil (product name "Diana Process Oil PW-100", manufactured by Idemitsu Kosan Co., Ltd.)

[0086] [Example 1] <Method for preparing a thermoplastic elastomer composition> 200 parts by mass of EPDM-1 as an ethylene-α-olefin-non-conjugated polyene copolymer (A) (uncrosslinked copolymer rubber (A)) (containing 100 parts by mass of ethylene-propylene-ENB copolymer rubber), 39.6 parts by mass of PP-1 as a propylene polymer (B), 4.4 parts by mass of PP-5 as an olefin resin (C), 170 parts by mass of paraffinic process oil as a plasticizer (E), 5 parts by mass of phenolic resin as a crosslinking agent (D), and 0.5 parts by mass of zinc oxide as a crosslinking aid were put into an extruder (model KTX-30, manufactured by Kobe Steel, Ltd.) and extruded and kneaded under the following conditions to dynamically crosslink the uncrosslinked composition and produce pellets of a crosslinked thermoplastic elastomer composition. The Shore A hardness of the obtained thermoplastic elastomer composition pellets was measured according to the measurement method described above. The results are shown in Table 1. <Extrusion Conditions> ・Cylinder temperature: C1: 50°C, C2: 50°C, C3: 100°C, C4: 150°C, C5: 150°C, C6: 180°C, C7: 180°C, C8-C14: 200°C ・Die temperature: 200°C ・Screw rotation speed: 400 rpm ・Extrusion rate: 80 kg / h

[0087] <Preparation of Foamed Molded Articles> Two parts by mass of a foaming agent (manufactured by Eiwa Chemical Industries, Ltd., brand name: Polyslene EE405F) were added to 100 parts by mass of the thermoplastic elastomer composition pellets obtained above. Using a 50 mm single-screw extruder (manufactured by Japan Steel Works Ltd., model number: P50-32ABV), a strand-shaped (mm) die was used to extrude under the conditions C1 / C2 / C3 / C4 / C5 / D1 = 160 / 160 / 170 / 180 / 180 / 180 (°C), and the material was taken up at 3.5 m / min to produce foamed molded articles (strands). The obtained foamed molded articles (strands) were evaluated as follows.

[0088] -Evaluation- [Foaming Properties] The density of the obtained thermoplastic elastomer composition and the density of the foamed molded article (strand) were measured using a water displacement densimeter in accordance with JIS K 7112. The foaming ratio was determined by dividing the density of the thermoplastic elastomer composition by the density of the foamed molded article (strand). If the foaming ratio is 1.4 times or higher, the foaming is good and can be said to be excellent. If the foaming ratio is less than 1.4 times, the foaming is judged to be poor.

[0089] [Surface Roughness (Appearance) of Foamed Molded Products] Five 10 cm foamed molded products (strands) were prepared, and the strand surface was visually inspected to measure the number of burst bubbles. The arithmetic mean of the number of burst bubbles was calculated and evaluated according to the following evaluation criteria. If the average number of burst bubbles on the strand surface is less than 5, the appearance can be considered good. -Evaluation Criteria- ○: The average number of burst bubbles on the strand surface was less than 5. ×: The average number of burst bubbles on the strand surface was 5 or more.

[0090] [Examples 2-13 and Comparative Examples 1-8] Thermoplastic elastomer composition pellets were prepared in the same manner as in Example 1, except that the raw materials were prepared to have the compositions shown in Table 1 or Table 2. The Shore A hardness of the obtained thermoplastic elastomer composition pellets was determined according to the measurement method described above. Furthermore, foamed molded articles were prepared using the obtained thermoplastic elastomer composition pellets in the same manner as in Example 1, and the foaming ratio and the surface roughness of the foamed molded articles were evaluated. The results are shown in Table 1 or Table 2.

[0091] In Tables 1 and 2, the values ​​in the "Uncrosslinked Copolymer Rubber (A)" column represent the value obtained by subtracting the oil-expanding amount from the oil-expanding ethylene-α-olefin-non-conjugated polyene copolymer (A). For example, "100.0" in the EPDM-1 column represents the value obtained by subtracting 100 parts by mass of oil-expanding amount from 200 parts by mass of oil-expanding ethylene-propylene-5-ethylidene-2-norbornene (ENB) copolymer rubber (i.e., the content of ethylene-propylene-ENB copolymer rubber).

[0092]

[0093]

[0094] In Tables 1 and 2, "-" indicates that the corresponding component is not present. Also, in Tables 1 and 2, the content ratio of propylene polymer (B) refers to the content ratio of olefin resin (B) relative to the total content of propylene polymer (B) and olefin resin (C), and the content ratio of olefin resin (C) refers to the content ratio of olefin resin (C) relative to the total content of propylene polymer (B) and olefin resin (C). Compared to the thermoplastic elastomer compositions of Comparative Examples 1 to 8, the thermoplastic elastomer compositions of Examples 1 to 13 exhibit superior foaming properties, and the appearance of the foamed molded articles obtained even when foamed is good.

Claims

1. The material comprises an ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), a propylene polymer (B) having a melt flow rate (MFR(B)) of 5 to 25 g / 10 min measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1, and an olefin resin (C) other than the propylene polymer (B), wherein the content of the propylene polymer (B) is 20 to 100 parts by mass per 100 parts by mass of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), and the olefin resin (B) has a melt flow rate (MFR(C)) of 5 to 25 g / 10 min measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1. A thermoplastic elastomer composition obtained by crosslinking a composition having a melt flow rate (MFR(B)) ratio (MFR(B) / MFR(C)) of 5 to 500, measured at 230°C and a 2.16 kg load in accordance with K7210-1.

2. The thermoplastic elastomer composition according to claim 1, wherein the melt flow rate (MFR(C)) of the olefin resin (C), measured at 230°C and a 2.16 kg load in accordance with JIS K7210-1, is 0.01 g / 10 min or more and less than 5 g / 10 min.

3. The thermoplastic elastomer composition according to claim 1, wherein the propylene polymer (B) is a polypropylene homopolymer or a propylene-ethylene copolymer.

4. The thermoplastic elastomer composition according to claim 1, wherein the intrinsic viscosity [η] of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), as measured in decalin at 135°C, is 4 dl / g or more.

5. The thermoplastic elastomer composition according to claim 1, wherein the amount of oil spreading per 100 parts by mass of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A) is 50 to 200 parts by mass.

6. The thermoplastic elastomer composition according to claim 1, wherein the composition further comprises a crosslinking agent (D), and the crosslinking agent (D) is a phenolic resin.

7. The thermoplastic elastomer composition according to claim 1, further comprising a crosslinking agent (D), wherein the crosslinking agent (D) is an organic peroxide.

8. The thermoplastic elastomer composition according to claim 1, further comprising a plasticizer (E).

9. The thermoplastic elastomer composition according to claim 8, wherein the content of the plasticizer (E) is 50 to 300 parts by mass per 100 parts by mass of ethylene-α-olefin-non-conjugated polyene copolymer rubber (A).

10. The thermoplastic elastomer composition according to claim 1, wherein the content ratio of the olefin resin (C) to the total content of the propylene polymer (B) and the olefin resin (C) is 7 to 70% by mass.

11. A molded article formed using the thermoplastic elastomer composition described in any one of claims 1 to 10.

12. The molded article according to claim 11, wherein the foaming ratio of the foamed molded article is 1.5 times or more.

13. The molded article according to claim 11, which is an automobile part.

14. The molded body according to claim 11, which is a sealing member for an automobile door.

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