Crosslinkable thermoplastic elastomer composition, crosslinked thermoplastic elastomer, and engine intake air duct using the same

Abstract

To provide a composition that satisfies the heat resistance, oil resistance, compression set properties and moldability required for engine intake ducts, and also has excellent oil permeation resistance.MEANS: There is provided a crosslinkable thermoplastic elastomer composition comprising: (a) 10 to 20 mass% of a propylene-based homopolymer; (b) 13 to 30 mass% of a block copolymer of a hard segment block composed of an aromatic vinyl unit and a soft segment block composed of a conjugated diene unit, or a hydrogenated product thereof; (c) 13 to 22 mass% of an ethylene-based copolymer rubber; and (d) 40 to 50 mass% of a non-aromatic rubber softener, wherein the total of the components (a), (b), (c), and (d) is 100 mass%, the hard segment block containing the aromatic vinyl compound of component (b) has a styrene unit and a styrene unit having a substituent and / or a vinylcyclohexene unit which may have a substituent, and the composition comprises 3 to 9 pts.mass of (e) a phenolic resin-based crosslinking agent based on 100 pts.mass of the total of components (b) and (c).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a crosslinkable thermoplastic elastomer composition, more specifically to a crosslinkable thermoplastic elastomer composition having excellent oil permeation resistance, a crosslinked thermoplastic elastomer obtained by dynamically crosslinking the composition, and an engine intake air duct made of the crosslinked thermoplastic elastomer. [Background technology]

[0002] Air intake ducts made of rubber or thermoplastic elastomer compositions are used in some of the air ducts that supply air to engines of automobiles, etc. In recent years, the use of thermoplastic elastomer air intake ducts has been desired from the viewpoints of material recyclability, weight reduction, and simplification of the molding cycle including the vulcanization process.

[0003] Incidentally, since air intake ducts used in automobiles and the like are located close to the engine intake port, they need to have resistance to engine oil, gasoline, combustion residues, etc. that leak from the engine, in addition to compression set and heat resistance. However, thermoplastic elastomers have low oil resistance, and engine oil can seep out onto the outer surface of the duct hose, and in some cases, they can swell, reducing rigidity and strength, so their applications are limited.

[0004] To address the above-mentioned problems, for example, Patent Document 1 describes improving oil resistance and the like by blending a copolymer in which nitrogen-containing vinyl polymer branch segments are grafted onto a propylene polymer backbone segment and a fatty acid amide with an olefin-based thermoplastic elastomer. Also, Patent Document 2 proposes a thermoplastic elastomer composed of polyester hard segments and aliphatic polycarbonate segments in order to improve the heat resistance of polyester-based thermoplastic elastomers.

[0005] Furthermore, Patent Document 3 proposes that by dynamically crosslinking a thermoplastic elastomer composition, it is possible to improve the mechanical strength and rubber elasticity while maintaining moldability. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-222449 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-150540 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-315619 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even in the engine intake ducts made of the thermoplastic elastomer compositions proposed in Patent Documents 1 and 2, etc., engine oil leaking from the engine side adheres to the inner surface of the intake duct and permeates to the outside of the intake duct, causing problems such as stickiness and poor appearance, and there is room for improvement in engine oil resistance, particularly oil permeation resistance. Similarly, the dynamically crosslinked thermoplastic elastomer composition described in Patent Document 3, etc., also does not have sufficient engine oil resistance, and there remains a problem in particular with respect to oil permeation resistance.

[0008] In view of the problems associated with conventional thermoplastic elastomer compositions, the present invention aims to provide a composition that satisfies the heat resistance, oil resistance, compression set properties and moldability required for engine intake ducts, and also has excellent oil permeation resistance. [Means for solving the problem]

[0009] As a result of intensive research aimed at solving the above problems, the present inventors have found that by adding a predetermined amount of a specific block copolymer rubber to an olefin-based thermoplastic elastomer comprising polypropylene and an ethylene-based copolymer rubber, it is possible to realize a crosslinkable thermoplastic elastomer composition that is excellent in oil resistance, particularly oil permeation resistance, while maintaining properties such as heat resistance and compression set. The present invention is based on this finding.

[0010] That is, the gist of the present invention is as follows. [1] (a) 10 to 20% by mass of a propylene homopolymer, (b) 13 to 30% by mass of a block copolymer or a hydrogenated product thereof having a hard segment block composed of an aromatic vinyl unit and a soft segment block composed of a conjugated diene unit, (c) 13 to 22 mass% of an ethylene copolymer rubber, (d) 40 to 50 mass% of a non-aromatic rubber softener, wherein the total of the components (a), (b), (c), and (d) is 100% by mass; The hard segment block containing the aromatic vinyl compound of component (b) has a styrene unit, a styrene unit having a substituent and / or a vinylcyclohexene unit which may have a substituent, For a total of 100 parts by mass of the components (b) and (c), (e) 3 to 9 parts by mass of a phenolic resin-based crosslinking agent, A crosslinkable thermoplastic elastomer composition comprising: [2] The crosslinkable thermoplastic elastomer composition according to [1], wherein the ratio of the components (b) and (c) is 35-65:65-35 on a mass basis. [3] The (b) block copolymer or its hydrogenated product, Styrene-methylstyrene-ethylene-propylene-styrene-methylstyrene, Styrene-vinylcyclohexene-ethylene-propylene-styrene-vinylcyclohexene, Styrene-methylstyrene-ethylene-ethylene-propylene-styrene-methylstyrene, Styrene-vinylcyclohexene-ethylene-ethylene-propylene-styrene-vinylcyclohexene, Styrene-methylstyrene-ethylene-butadiene-styrene-methylstyrene, and Styrene-vinylcyclohexene-ethylene-butadiene-styrene-vinylcyclohexene, The crosslinkable thermoplastic elastomer composition according to [1] or [2], wherein the crosslinkable thermoplastic elastomer composition is at least one selected from the group consisting of: [4] The crosslinkable thermoplastic elastomer composition according to any one of [1] to [3], wherein the (a) propylene homopolymer has an MFR of 0.1 to 3 g / 10 min, as measured in accordance with JIS K 7112 at 230°C and 21.18 N. [5] A crosslinked thermoplastic elastomer obtained by dynamically crosslinking the crosslinkable thermoplastic elastomer composition according to any one of [1] to [4]. [6] The thermoplastic elastomer crosslinked product according to [5], which is used for producing an engine intake air duct molding. [7] An engine intake air duct made of the crosslinked thermoplastic elastomer according to [5] or [6]. [Effects of the Invention]

[0011] According to the present invention, it is possible to realize a thermoplastic elastomer composition that satisfies the heat resistance, oil resistance, compression set properties and moldability required for engine intake ducts, and also has excellent oil permeation resistance. DETAILED DESCRIPTION OF THE INVENTION

[0012] The crosslinkable thermoplastic elastomer composition of the present invention contains, as essential components, (a) a propylene-based homopolymer, (b) a predetermined block copolymer or its hydrogenated product, (c) an ethylene-based copolymer rubber, (d) a non-aromatic rubber softener, and (e) a phenolic resin-based crosslinking agent. Each component constituting the crosslinkable thermoplastic elastomer composition of the present invention will be described below.

[0013] <(a) Propylene homopolymer> The propylene homopolymer of component (a) is a polymer composed only of propylene units, and because it is crystalline and has a high melting point, it can improve the heat resistance of the crosslinked product obtained by dynamically crosslinking the crosslinkable thermoplastic elastomer composition. It also retains engine oil in the crosslinked product, preventing its permeation.

[0014] The propylene homopolymer preferably has an MFR (melt mass flow rate) of 0.1 to 3.0 g / 10 min, more preferably 0.3 to 2.5 g / 10 min, as measured in accordance with JIS K7210-1999 at 230°C and 21.18 N. (a) When the MFR of the propylene homopolymer is within the above range, it is possible to achieve both moldability and engine oil permeation resistance at a higher level.

[0015] From the viewpoint of heat resistance, the melting point of the propylene homopolymer (a) is preferably 155°C or higher. There is no particular upper limit to the melting point, but since it is a polypropylene-based resin, the upper limit is usually about 167°C. Unless otherwise specified, the melting point refers to the peak-top melting point of the peak that appears on the highest temperature side in the second melting curve (i.e., the melting curve measured during the final heating process) measured using a DSC-type differential scanning calorimeter (e.g., Diamond from PerkinElmer Japan Co., Ltd.) using a program that involves holding at 230°C for 5 minutes, cooling to -10°C at 10°C / min, holding at -10°C for 5 minutes, and then heating to 230°C at 10°C / min.

[0016] The blending amount of component (a) propylene homopolymer is 10 to 20 mass%, preferably 12 to 19 mass%, relative to 100 mass% of the total of components (a), (b), (c), and (d). If it is less than 10 mass%, molding processability deteriorates, and if it exceeds 20 mass%, oil permeation resistance deteriorates.

[0017] <(b) Block copolymer of aromatic vinyl compound and conjugated diene compound> Component (b) is a block copolymer or a hydrogenated product thereof of a hard segment block composed of aromatic vinyl units and a soft segment block composed of conjugated diene units. The incorporation of such a block copolymer or a hydrogenated product thereof can improve oil resistance, particularly oil permeation resistance, without impairing molding processability. The reason for this is unclear, but is presumed to be as follows. That is, while thermoplastic elastomers composed of a propylene homopolymer and an ethylene copolymer rubber, such as EPDM, have insufficient oil retention, the incorporation of the above-mentioned specific block copolymer or a hydrogenated product thereof is thought to improve oil retention while maintaining heat resistance, compression set, and molding processability.

[0018] The block copolymer of aromatic vinyl units and conjugated diene units of component (b) is usually a block copolymer having one or more hard segment blocks X, preferably two or more from the viewpoint of mechanical properties, mainly composed of structural units derived from an aromatic vinyl compound, and one or more soft segment blocks Y mainly composed of structural units derived from a conjugated diene compound. Examples of such block copolymers include those having structures such as XY, XYX, YXYX, and XYXYX.

[0019] The hydrogenated block copolymer of component (b) can be obtained by adding hydrogen to the carbon-carbon double bonds in the block copolymer of aromatic vinyl units and conjugated diene units to convert them to carbon-carbon single bonds. The hydrogenation can be carried out by a known method, for example, by hydrogenation in an inert solvent using a hydrogenation catalyst.

[0020] The hydrogenation ratio of the hydrogenated product of a block copolymer of aromatic vinyl units and conjugated diene units (i.e., the ratio of the number of carbon-carbon single bonds generated by hydrogenation to the number of carbon-carbon double bonds in the block copolymer before hydrogenation) is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more, from the viewpoint of improving heat resistance. The hydrogenation ratio mentioned above means the value measured by 1H-NMR, unless otherwise specified.

[0021] The aromatic vinyl units constituting the hard segment blocks are polymerizable monomer units having a polymerizable carbon-carbon double bond and an aromatic ring, and are copolymers of styrene units and substituted styrene units and / or optionally substituted vinylcyclohexene units. Examples of substituted styrene units include methylstyrene, ethylstyrene, t-butylstyrene, α-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, and alkylstyrenes in which at least one alkyl group having 1 to 8 carbon atoms is bonded to the benzene ring. Among these, alkylstyrenes in which at least one alkyl group having 1 to 8 carbon atoms is bonded to the benzene ring are preferred. The substituted styrene units do not include styrene. One or more of these compounds can be used as the benzene skeleton-containing compound.

[0022] Examples of alkylstyrenes in which at least one alkyl group having 1 to 8 carbon atoms is bonded to a benzene ring include alkylstyrenes such as o-alkylstyrene, m-alkylstyrene, p-alkylstyrene, 2,4-dialkylstyrene, 3,5-dialkylstyrene, and 2,4,6-trialkylstyrene, as well as halogenated alkylstyrenes in which one or more hydrogen atoms of the alkyl group in these alkylstyrenes have been substituted with halogen atoms. More specifically, for example, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-diethylstyrene, 3,5-diethylstyrene, 2,4,6-triethylstyrene, o-propylstyrene, m-propylstyrene, p-propylstyrene, 2,4-dipropylstyrene, 3,5-dipropylstyrene, 2,4,6-tripropylstyrene, 2-methyl-4-ethylstyrene, 3-methyl-5-ethylstyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene, 2,4-bis(chloromethyl)styrene, 3,5-bis(chloromethyl)styrene, 2,4,6-tri(chloromethyl)styrene, o-dichloromethylstyrene, m-dichloromethylstyrene, and p-dichloromethylstyrene. Among these, p-methylstyrene is particularly preferred from the viewpoint of crosslinkability.

[0023] Examples of the vinylcyclohexene unit which may have a substituent include cyclohexene, methylcyclohexene, ethylcyclohexene, t-butylcyclohexene, vinylcyclohexene, and alkylcyclohexene in which at least one alkyl group having 1 to 8 carbon atoms is bonded to the cyclohexene ring. Among these, ethylcyclohexene and vinylcyclohexene are preferred from the viewpoint of crosslinkability. As the vinylcyclohexene unit which may have a substituent, one or more of these can be used.

[0024] The aromatic vinyl compound is a copolymer consisting of a styrene unit and one or more of the above-mentioned substituted styrene units and / or vinylcyclohexene units which may have a substituent. From the viewpoint of moldability and oil permeation resistance, the hard segment of component (b) preferably consists of a styrene unit and one or more substituted styrene units.

[0025] In the hard segment block X, the proportion of the styrene units having the above substituents and / or vinylcyclohexene units which may have a substituent is preferably 1% by mass or more, more preferably 50% by mass or more, and may even be 100% by mass, from the viewpoint of crosslinkability.

[0026] The conjugated diene unit constituting the soft segment block of component (b) is a polymerizable monomer having a structure in which two carbon-carbon double bonds are bonded by one carbon-carbon single bond. Examples of conjugated diene compounds include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and chloroprene (2-chloro-1,3-butadiene). Among these, 1,3-butadiene and isoprene are preferred. One or more of these can be used as the conjugated diene unit constituting the soft segment block.

[0027] The proportion of aromatic vinyl units in the block copolymer or hydrogenated product thereof of a hard segment block composed of aromatic vinyl units and a soft segment block composed of conjugated diene units is not particularly limited, but from the viewpoints of mechanical strength, cold resistance, heat resistance, and flexibility, it is preferably 5 to 50 mass % and more preferably 20 to 40 mass % relative to the total mass of component (b).

[0028] The hard segment block X of component (b) preferably consists solely of the aromatic vinyl units described above, but may also contain monomer units other than the aromatic vinyl units described above, such as a copolymer block of the aromatic vinyl compound and the conjugated diene unit. When the hard segment block X contains the conjugated diene unit, the proportion of the aromatic vinyl unit in the hard segment block is not particularly limited, but from the viewpoint of heat resistance, it is usually preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. In addition, the distribution of the conjugated diene unit in the hard segment block X is not particularly limited. When the block copolymer of component (b) contains two or more hard segment blocks X, they may have the same structure or different structures.

[0029] The soft segment block Y of component (b) preferably consists solely of the conjugated diene units described above, but may also contain monomer units other than the conjugated diene units. For example, the soft segment block Y may be a copolymer block of the aromatic vinyl compound and the conjugated diene units described above. When the soft segment block Y contains the aromatic vinyl units, the proportion of the conjugated diene units in the soft segment block is not particularly limited. However, from the viewpoint of heat resistance, it is usually preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. The distribution of the aromatic vinyl units in the soft segment block Y is not particularly limited. The bonding mode between the conjugated diene units and the aromatic vinyl units is also not particularly limited. When the block copolymer of component (b) contains two or more soft segment blocks Y, they may have the same structure or different structures.

[0030] Examples of the component (b) block copolymer include a styrene-methylstyrene (and / or vinylcyclohexene)-butadiene-styrene-methylstyrene (and / or vinylcyclohexene) block copolymer, a styrene-methylstyrene (and / or vinylcyclohexene)-isoprene-styrene-methylstyrene (and / or vinylcyclohexene) block copolymer, and the like, in which the hard segment block has a styrene unit and a styrene unit having a substituent and / or a vinylcyclohexene unit which may have a substituent.

[0031] Furthermore, examples of hydrogenated block copolymers of component (b) include copolymers in which the soft segment block has a styrene unit and a styrene unit having a substituent and / or a vinylcyclohexene unit which may have a substituent, such as a styrene-methylstyrene (and / or vinylcyclohexene)-ethylene-butene block copolymer, a styrene-methylstyrene (and / or vinylcyclohexene)-ethylene-propylene block copolymer, a styrene-methylstyrene (and / or vinylcyclohexene)-ethylene-butene-styrene-methylstyrene (and / or vinylcyclohexene) block copolymer, a styrene-methylstyrene (and / or vinylcyclohexene)-ethylene-propylene-styrene-methylstyrene (and / or vinylcyclohexene) block copolymer, and a styrene-methylstyrene (and / or vinylcyclohexene)-ethylene-ethylene-propylene-styrene-methylstyrene (and / or vinylcyclohexene) block copolymer.

[0032] Among these, from the viewpoint of abrasion resistance when crosslinked, styrene-methylstyrene (and / or vinylcyclohexene)-ethylene-propylene-styrene-methylstyrene (and / or vinylcyclohexene) block copolymers, styrene-methylstyrene (and / or vinylcyclohexene)-ethylene-ethylene-propylene-styrene-methylstyrene (and / or vinylcyclohexene) block copolymers, and styrene-methylstyrene (and / or vinylcyclohexene)-ethylene-butadiene-styrene-methylstyrene (and / or vinylcyclohexene) block copolymers are preferred, and styrene-methylstyrene-ethylene-propylene-styrene-methylstyrene block copolymers and styrene-methylstyrene-ethylene-ethylene-propylene-styrene-methylstyrene block copolymers are particularly preferred.

[0033] The mass average molecular weight (Mw) of the block copolymer of component (b) is preferably 150,000 to 500,000. From the viewpoint of obtaining a molded article (crosslinked article) with good oil permeation resistance, the lower limit of Mw is preferably 150,000 or more, more preferably 180,000 or more, and even more preferably 200,000 or more. On the other hand, from the viewpoint of processability during molded article production, the upper limit of Mw is preferably 500,000 or less, more preferably 450,000 or less, and even more preferably 400,000 or less. Unless otherwise specified, the mass average molecular weight (Mw) refers to a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0034] The blending amount of the block copolymer or hydrogenated product thereof of component (b) is 13 to 30% by mass, preferably 14 to 22% by mass, and more preferably 16 to 20% by mass, relative to 100% by mass of the total of components (a), (b), (c), and (d). If the blending amount of component (b) is less than 13% by mass, the crosslink density is low and oil permeation resistance deteriorates, whereas if it exceeds 30% by mass, oil resistance and moldability deteriorate.

[0035] <(c) Ethylene copolymer rubber> The component (c) ethylene copolymer rubber is a copolymer rubber mainly composed of ethylene and an α-olefin. The component (c) imparts flexibility to the crosslinked product of the thermoplastic elastomer composition and contributes to improving the compression set (reducing the compression set).

[0036] Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 2-methyl-1-propene, 2-methyl-1-butene, 3-methyl-1-butene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 3-methyl-1-pentene, and 4-methyl-1-pentene. Among these, α-olefins having 3 to 10 carbon atoms are preferred. As the α-olefin, one of these or a mixture of two or more thereof can be used.

[0037] The component (c) ethylene copolymer rubber may contain, in addition to ethylene and an α-olefin, structural units derived from a monomer copolymerizable with these.

[0038] Examples of copolymerizable monomers include non-conjugated diene monomers. Examples of the non-conjugated diene monomers include 5-ethylidene-2-norbornene (ENB), 1,4-hexadiene, 5-methylene-2-norbornene (MNB), 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, 1,3-cyclopentadiene, 1,4-cyclohexadiene, tetrahydroindene, methyltetrahydroindene, dicyclopentadiene, 5-isopropylidene-2-norbornene, 5-vinyl-norbornene, dicyclooctadiene, methylenenorbornene, ethylidenenorbornene, norbornadiene, 1,2-butadiene, and 1,4-pentadiene. The copolymerizable monomers may be used alone or in combination.

[0039] Specific examples of the component (c) ethylene copolymer rubber include ethylene-propylene copolymer rubber, ethylene-propylene-non-conjugated diene copolymer rubber, ethylene-1-butene copolymer rubber, ethylene-1-butene-non-conjugated diene copolymer rubber, ethylene-1-octene copolymer rubber, ethylene-1-octene-non-conjugated diene copolymer rubber, ethylene-propylene-1-butene copolymer rubber, and ethylene-propylene-1-octene copolymer rubber. Among these, ethylene-propylene-non-conjugated diene copolymer rubber (EPDM) is preferred from the viewpoint of flexibility. As the component (c) ethylene copolymer rubber, one or a mixture of two or more of these can be used.

[0040] Oil-extended EPDM can also be used as component (c) ethylene copolymer rubber. The amount of oil extension relative to the EPDM is about 30 to 120% by weight. For oil extension, the following component (d) is preferably used.

[0041] The content of ethylene-derived structural units in the component (c) ethylene copolymer rubber varies depending on the type of α-olefin copolymerized with ethylene and the molecular structure (whether it is linear or has long-chain branches, etc.), but is preferably 50 to 90 mass%, more preferably 60 to 85 mass%.

[0042] The Mooney viscosity ML1+4 of the component (c) ethylene copolymer rubber measured at 125°C in accordance with ASTM D-1646 is not particularly limited, but from the viewpoint of compression set, it is preferably 10 or more, more preferably 20 or more. On the other hand, from the viewpoint of molding processability, it is preferably 180 or less, more preferably 150 or less.

[0043] The density of the component (c) ethylene copolymer rubber measured in accordance with JIS K 7112:1999 is preferably 850 to 900 kg / m 3 , more preferably 855 to 890 kg / m 3 is.

[0044] The amount of component (c) ethylene copolymer rubber is 13 to 22% by mass, preferably 16 to 20% by mass, based on 100% by mass of the total of components (a), (b), (c), and (d). If the amount of component (c) is less than 13% by mass, compression set deteriorates, and if it exceeds 22% by mass, oil permeation resistance deteriorates. When oil-extended EPDM is used as component (c) ethylene copolymer rubber, the amount of EPDM alone is used. When the oil-extended oil is component (d) a non-aromatic rubber softener, the amount of component (d) described below is used.

[0045] The blending ratio of the above components (b) and (c) is preferably 35-65:65-35 by mass, more preferably 40-60:60-40, and even more preferably 50:50. The closer the blending ratio of components (b) and (c) is to 1, the better the oil permeation resistance and molding processability.

[0046] <(d) Non-aromatic rubber softeners> The non-aromatic rubber softener of component (d) functions to improve molding processability and flexibility. (d) Non-aromatic rubber softener is a non-aromatic mineral oil (hydrocarbon compound derived from petroleum, etc.) or synthetic oil (synthetic hydrocarbon compound), and is usually liquid, gel-like, or gum-like at room temperature. Here, "non-aromatic" means that for mineral oils, they are not classified as aromatic in the classification below (the number of aromatic carbon atoms is less than 30%). For synthetic oils, this means that aromatic monomers are not used.

[0047] Mineral oils used as rubber softeners are mixtures of one or more of paraffin chains, naphthenic rings, and aromatic rings. They are classified as follows: those with 30 to 45% naphthenic ring carbon atoms are called naphthenic, those with 30% or more aromatic carbon atoms are called aromatic, and those that are neither naphthenic nor aromatic and have paraffin chain carbon atoms that account for 50% or more of the total carbon atoms are called paraffinic.

[0048] Examples of non-aromatic rubber softeners (component (d)) include paraffinic mineral oils such as linear saturated hydrocarbons, branched saturated hydrocarbons, and their derivatives; naphthenic mineral oils; and synthetic oils such as hydrogenated polyisobutylene, polyisobutylene, and polybutene. Commercially available examples include the isoparaffinic hydrocarbon oil "NA Solvent" (trade name) from Nippon Oil & Fats Corporation, the n-paraffinic process oils "Diana Process Oil PW-100" and "Diana Process Oil PW-380" (trade name) from Idemitsu Kosan Co., Ltd., the synthetic isoparaffinic hydrocarbon "IP-Solvent 2835" (trade name) from Idemitsu Petrochemical Co., Ltd., and the n-paraffinic process oil "Neothiosol" (trade name) from Sanko Chemical Industry Co., Ltd. Among these, paraffinic mineral oils are preferred from the standpoint of compatibility, with paraffinic mineral oils with a low aromatic carbon number being more preferred. Furthermore, from the standpoint of ease of handling, those that are liquid at room temperature are preferred. As the non-aromatic rubber softener of component (d), one or more of these can be used.

[0049] From the viewpoints of heat resistance and handleability, the (d) non-aromatic rubber softener preferably has a dynamic viscosity at 37.8°C measured in accordance with JIS K 2283:2000 of 20 to 1000 cSt. From the viewpoint of handleability, the pour point measured in accordance with JIS K 2269:1987 is preferably -25 to -10°C. Furthermore, from the viewpoint of safety, the flash point (COC) measured in accordance with JIS K 2265:2007 is preferably 170 to 300°C.

[0050] The amount of (d) non-aromatic rubber softener is 40 to 50% by mass, and more preferably 43 to 47% by mass, based on 100% by mass of the total of the above components (a), (b), (c), and (d). If the amount of component (d) is less than 40% by mass, the composition will be hard, lacking flexibility, and poor moldability, while if it exceeds 50% by mass, it will be unable to retain oil, reducing oil permeation resistance and making bleeding more likely to occur.

[0051] <(e) Phenolic resin-based crosslinking agent> (e) The phenolic resin-based crosslinking agent functions to crosslink the components (b) together, the components (c) together, and the components (b) and (c).

[0052] Phenolic resin crosslinkers, also known as resole resins, are produced by condensing alkyl-substituted or unsubstituted phenols with aldehydes, preferably formaldehyde, in an alkaline medium, or by condensing difunctional phenol dialcohols. The alkyl substituents in alkyl-substituted phenols typically have 1 to about 10 carbon atoms. Dimethylolphenols or phenolic resins substituted with alkyl groups having 1 to about 10 carbon atoms at the para-position are preferred. These phenolic crosslinkers are typically thermosetting resins and are referred to as phenolic resin crosslinkers or phenolic resins. Specific examples of crosslinking thermoplastic vulcanizates with phenolic resins are described in U.S. Pat. Nos. 4,311,628, 2,972,600, and 3,287,440, and these techniques can also be used in the present invention.

[0053] A preferred phenolic resin-based crosslinking agent is, for example, a compound represented by general formula (I).

[0054] [ka]

[0055] In the formula, Q is a divalent group selected from the group consisting of -CH2- and CH2-O-CH2-, preferably -CH2-; m is 0 or a natural number from 1 to 20, preferably 0 or a natural number from 1 to 10, more preferably 0 or a natural number from 1 to 5; R is an organic group, preferably an organic group having 1 to 20 carbon atoms, more preferably an organic group having 4 to 12 carbon atoms, and the organic group is preferably an alkyl group.

[0056] Among phenolic resins, alkylphenol formaldehyde resins and methylolated alkylphenol resins are preferred. Brominated phenolic resins in which the terminal hydroxyl groups are brominated, such as brominated alkylphenol resins, are also preferred. Alkylphenol formaldehyde resins are particularly preferred.

[0057] Commercially available examples of phenolic resin-based crosslinking agents include Tackirol 201, 202 (alkylphenol formaldehyde resins, manufactured by Taoka Chemical Co., Ltd.), Tackirol 250-I (brominated alkylphenol formaldehyde resin with a bromination rate of 4%, manufactured by Taoka Chemical Co., Ltd.), Tackirol 250-III (brominated alkylphenol formaldehyde resin, manufactured by Taoka Chemical Co., Ltd.), PR-4507 (manufactured by Gunei 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), Vulkaresol 315E (manufactured by Hoechst), and Amberol ST. 137X (manufactured by Rohm & Haas), Sumilite Resin PR-22193 (manufactured by Sumitomo Durez Co., Ltd.), Symphorm-C-100 (manufactured by Anchor Chem.), Symphorm-C-1001 (manufactured by Anchor Chem.), Tamanor 531 (manufactured by Arakawa Chemical Co., Ltd.), Schenectady SP1059 (manufactured by Schenectady Chem.), Schenectady SP1045 (manufactured by Schenectady Chem.), CRR-0803 (manufactured by UCC), Schenectady SP1055 (manufactured by Schenectady Chem.), Schenectady SP1056 (manufactured by Schenectady Chem.), CRM-0803 (manufactured by Showa Union Synthetic Co., Ltd.), Vulkadur A (manufactured by Bayer), among which Tackirol 201 (alkylphenol formaldehyde resin) can be preferably used.

[0058] The blending amount of (e) phenolic resin-based crosslinking agent is 3 to 9 parts by mass, preferably 4 to 8 parts by mass, per 100 parts by mass of the total of components (b) and (c). If the blending amount of component (e) is less than 3 parts by mass, the crosslinking efficiency decreases, and compression set and oil permeation resistance deteriorate. Blending an amount exceeding 9 parts by mass is meaningless because crosslinking does not proceed.

[0059] (e) The phenolic resin-based crosslinking agent can also be used in advance as a masterbatch. Forming it into a masterbatch is useful in terms of workability, dispersibility, etc. The binder component of the masterbatch can be selected arbitrarily as long as it does not affect the present invention, but it is preferable to use, for example, a polypropylene-based polymer or a styrene-based block copolymer of the same type as the compounding ingredients of the composition of the present invention.

[0060] <Other ingredients> The crosslinkable thermoplastic elastomer composition of the present invention may further contain heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents, antiblocking agents, sealability improvers, release agents such as stearic acid and silicone oil, lubricants such as polyethylene wax, colorants, pigments, inorganic fillers (alumina, talc, calcium carbonate, mica, vulcanite, clay), foaming agents (organic and inorganic), flame retardants (metal hydrates, red phosphorus, ammonium polyphosphate, antimony, silicone), and the like, as long as they do not affect the present invention.

[0061] The crosslinkable thermoplastic elastomer composition of the present invention can be produced by adding the above components (a) to (e) and, if necessary, other components, simultaneously or in any order, and mixing them. As mentioned above, component (e) can also be used in the form of a masterbatch in advance.

[0062] The melt-kneading method is not particularly limited, and commonly known methods can be used. For example, a single-screw extruder, twin-screw extruder, roll, Banbury mixer, or various kneaders can be used. For example, the above operation can be carried out continuously by using a twin-screw extruder, Banbury mixer, pressure kneader, or the like with an appropriate L / D ratio. Here, the melt-kneading temperature is preferably 160 to 200°C, and the kneading time is preferably 5 to 30 minutes to allow crosslinking to proceed sufficiently. More preferably, it is 10 to 20 minutes.

[0063] Specific applications include engine intake air ducts, as well as automotive parts such as lighting gaskets, 3D Exchange Blow Clean air ducts, Fooloseal hinge covers, belly pans (Robotech Extrusion Gaskets), cup holders, handbrake grips, shift knob covers, seat adjustment knobs, IP skins, flapper door seals, wire harness grommets, rack and pinion boots, suspension cover boots (strut cover boots), glass guides, inner belt line seals, roof guides, trunk lid seals, molded quarter window gaskets, corner moldings, glass encapsulation (Robotech Extrusion), hood seals, glass encapsulation (injection molding), glass run channels, and secondary seals. In addition, as industrial parts, curtain wall gaskets for high-rise buildings, window frame seals, adhesion to metals / reinforced fibers, parking deck seals, expansion joints, earthquake expansion joints, residential window and door seals (e.g., co-extrusion), residential door seals, handrail coverings, walking mats (sheets, foot rubber, washing machine drain hoses (two-color molding with PP, etc.), washing machine lid seals, air conditioner motor mounts, drain pipe seals (two-color molding with PP, etc.), riser tubes (PVC, etc.), caster wheels, printer rolls, duct hoses, wire & Examples of applications include cables, syringe syringe gaskets, etc. Furthermore, the material can be suitably used in daily necessities and parts such as speaker surrounds, hairbrush grips, razor grips, cosmetic grips and feet, toothbrush grips, daily necessities brush grips, broom bristles, kitchen utensil grips, measuring spoon grips, pruning shears grips, heat-resistant glass container lids, gardening tool grips, scissors grips, stapler grips, computer mice, golf bag parts, wall plastering trowel grips, chainsaw grips, screwdriver grips, hammer grips, electric drill grips, sander grips, alarm clocks, etc. [Example]

[0064] Next, the embodiments of the present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0065] In this specification, the manufacturing methods, evaluation methods and raw materials of the test specimens used in the examples and comparative examples are as follows.

[0066] <Evaluation method> (1) Oil permeability resistance Each pellet, described below, was injection molded into a sheet measuring 130 mm long, 130 mm wide, and 5 mm thick, with a 30 mm long, 30 mm wide, and 2 mm deep depression in the approximate center. 1.5 g of engine oil (Nissan SN Strong Save X, 0W-20, manufactured by Nissan Motor Co., Ltd.) was dripped into the depression of the resulting sheet to fill the depression with engine oil. The sheet with the oil-filled depression was placed in a thermostatic chamber at 120°C. After 72 hours, a paper cloth (Kimwipe, manufactured by Nippon Paper Crecia Co., Ltd.) was pressed against the reverse side of the depression. The surface of the paper cloth pressed against the pressed side was observed to evaluate the engine oil permeability. The evaluation criteria were as follows: ○: No oil transfer is observed on the surface of the paper cloth ×: Oil transfer is observed on the surface of the paper cloth The evaluation results are shown in Tables 1 and 2.

[0067] (2) Oil resistance (volume swelling rate) Using each of the pellets described below, a 2 mm thick injection sheet was prepared in accordance with JIS K 6258 and used as a test specimen. The obtained test specimen was immersed in engine oil (Nissan SN Strong Save X, 0W-20, manufactured by Nissan Motor Co., Ltd.) at 120°C for 168 hours, and then the volume swelling ratio was measured. The measurement results are shown in Tables 1 and 2. The preferred volume swelling ratio is 62% or less.

[0068] (3) Heat resistance (100% modulus at 120°C tensile test) Using each of the pellets described below, a 2 mm thick injection sheet in the shape of a No. 3 dumbbell was prepared in accordance with JIS K 6258 (tensile test) and used as a test specimen. The obtained test specimen was left to stand in a thermostatic chamber at 120°C for 1 minute, and then the 100% modulus was measured at 500 mm / min using a tensile tester (Strograph TF-50F, manufactured by Toyo Seiki Seisaku-sho, Ltd.). The measurement results are shown in Tables 1 and 2. The preferred range of 100% modulus is 1.1 to 1.5 MPa.

[0069] (4) Compression set Using each pellet described below, a cylindrical press sheet having a thickness of 6.3 mm was prepared in accordance with JIS K 6262 and used as a test specimen. The obtained test specimen was given a compressive strain equivalent to 25% of the thickness and held at 120°C for 22 hours, after which the strain was released and the compression set rate (%) was measured after 1 hour. The measurement results are shown in Tables 1 and 2. The preferred range of compression set is less than 34%.

[0070] (5)Hardness Using each of the pellets described below, a 6.3 mm thick cylindrical press sheet conforming to JIS K 6253 was prepared as a test specimen. The obtained test specimen was measured for durometer hardness, type A (Shore A), using a durometer (Auto Durometer P-2 model, manufactured by Kobunshi Keiki Co., Ltd.). The measurement results are shown in Tables 1 and 2. The preferred hardness range is 67 to 73.

[0071] (6) MFR Using each pellet described below, measurements were carried out under conditions of 230°C and 10 kg in accordance with JIS K 7112. The measurement results are shown in Tables 1 and 2. The preferred MFR range is 14-60.

[0072] (7) Molding processability Each pellet described below was injection molded using a mold for automobile engine air ducts, and moldability was evaluated. The evaluation criteria were as follows: ○: A molded product with a good shape can be obtained ×: Even when the molding conditions were adjusted, cracks, sink marks, or flow marks occurred in the molded product, and a molded product with a good shape could not be obtained. The evaluation results are shown in Tables 1 and 2.

[0073] <Materials used> Component (a) (a-1) SunAllomer VX200N Polypropylene homopolymer, MFR: 0.5g / 10min, Melting point: 164℃ (a-2) SunAllomer PB222A Polypropylene random copolymer, MFR: 0.75g / 10min, Melting point: 146℃ (a-3) SunAllomer VB370A Polypropylene block copolymer, MFR: 1.3g / 10min, Melting point: 162℃

[0074] Ingredient (b) (b-1) Kuraray Septon V9461 SEEPS, an aromatic vinyl compound copolymer of styrene and p-methylstyrene, mass average molecular weight: 300,000 (b-2) Tuftec N510 manufactured by Asahi Kasei Chemicals Corporation SEBS, an aromatic vinyl compound copolymer of styrene, 4-ethylcyclohexene, and 4-vinylcyclohexene, with a mass average molecular weight of 260,000 (b-3) Kuraray Septon 4077 SEPS, hydrogenation rate: 90% or more, mass average molecular weight: 320,000

[0075] Ingredient (c) (c-1) Nordel IP4760P manufactured by Dow Chemical Company EPDM, ethylene-derived structural unit content: 67%, Mooney viscosity: 60, density: 0.88 kg / m 3 (c-2) Mitsui Chemicals 3072EPM, EPDM with an oil extension rate of 40 phr, extended component: paraffin oil, content of ethylene-derived structural units: 64%, Mooney viscosity: 51, density: 0.87 kg / m 3

[0076] Ingredient (d) (d-1) Idemitsu Kosan PW-100 Paraffin oil

[0077] Ingredient (e) (e-1) Taoka Chemical Co., Ltd. Takkiroll 202 Alkylphenol formaldehyde resin

[0078] The above-mentioned raw materials were mixed according to the composition shown in Table 1, melt-kneaded using a twin-screw extruder (TEX28, manufactured by The Japan Steel Works, Ltd.), and pelletized. The obtained pellets were used to prepare various test pieces as described above, and each evaluation was performed. The evaluation results are shown in Table 1. The blending amount (numerical value) of each component in the table represents parts by mass. In addition, in Table 1, the blending amount of 3072 EPM as component (c) in Example 7 does not include paraffin oil, which is an oil-extending component, and the amount of this oil-extending paraffin oil is expressed as the total blending amount of paraffin as component (d).

[0079] [Table 1]

[0080] [Table 2]

Claims

1. A crosslinkable thermoplastic elastomer composition before dynamic crosslinking of a thermoplastic elastomer crosslinked product used in the production of an engine intake air duct molding, comprising: (a) 10 to 20% by mass of a propylene homopolymer, (b) 13 to 30% by mass of a block copolymer or a hydrogenated product thereof, the block copolymer comprising a hard segment block mainly composed of structural units derived from an aromatic vinyl compound and a soft segment block mainly composed of structural units derived from a conjugated diene compound, (c) 13 to 22 mass% of an ethylene copolymer rubber, (d) 40 to 50% by mass of a non-aromatic rubber softener, wherein the total of the components (a), (b), (c), and (d) is 100% by mass; The hard segment block containing the aromatic vinyl compound of component (b) has a styrene unit, a styrene unit having a substituent and / or a vinylcyclohexene unit which may have a substituent, For a total of 100 parts by mass of the components (b) and (c), (e) 3 to 9 parts by mass of a phenolic resin-based crosslinking agent, A crosslinkable thermoplastic elastomer composition comprising:

2. 2. The crosslinkable thermoplastic elastomer composition according to claim 1, wherein the ratio of components (b) to (c) is 35 to 65:65 to 35 on a mass basis.

3. The (b) block copolymer or its hydrogenated product is Styrene-methylstyrene-ethylene-propylene-styrene-methylstyrene, styrene-vinylcyclohexene-ethylene-propylene-styrene-vinylcyclohexene, Styrene-methylstyrene-ethylene-ethylene-propylene-styrene-methylstyrene, styrene-vinylcyclohexene-ethylene-ethylene-propylene-styrene-vinylcyclohexene, Styrene-methylstyrene-ethylene-butadiene-styrene-methylstyrene, and styrene-vinylcyclohexene-ethylene-butadiene-styrene-vinylcyclohexene, The crosslinkable thermoplastic elastomer composition according to claim 1 or 2, wherein the crosslinkable thermoplastic elastomer composition is at least one selected from the group consisting of:

4. The crosslinkable thermoplastic elastomer composition according to any one of claims 1 to 3, wherein the (a) propylene homopolymer has an MFR of 0.1 to 3 g / 10 min, as measured in accordance with JIS K 7112 under conditions of 230°C and 21.18 N.

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