Thermoplastic elastomer composition

Abstract

To provide a thermoplastic elastomer composition with excellent gas barrier properties and heat resistance. [Solution] A thermoplastic elastomer composition comprising (A) an isobutylene-isoprene copolymer elastomer, (B) polypropylene, preferably polypropylene with a melting enthalpy of 50 J / g or more, and (C) a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound (excluding those containing a softening agent). (C) The hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound may have constituent units derived from β-farnesene. Furthermore, (D) petroleum resin or the like may be included. (E) Dynamic crosslinking may be performed using a phenolic resin crosslinking agent.

Description

[Technical Field]

[0001] This invention relates to thermoplastic elastomer compositions. [Background technology]

[0002] Conventionally, thermoplastic elastomer compositions obtained by melt-kneading a composition containing isobutylene-isoprene copolymer elastomer, polypropylene, and a rubber softener in the presence of a crosslinking agent such as a phenolic resin have been proposed as materials for sealing members such as medical plugs due to their excellent gas barrier properties. On the other hand, these thermoplastic elastomer compositions have the disadvantage that the rubber softener bleeds out when used at high temperatures for extended periods. Therefore, Patent Document 1 proposes using an olefin-based low-crystalline polymer instead of the rubber softener. However, the thermoplastic elastomer composition of Patent Document 1 contains a large amount of an olefin-based low-crystalline polymer that has the properties of a wax or hot-melt adhesive, resulting in insufficient heat resistance, and therefore, when used as a material for medical plugs, it has the disadvantage of not being able to be subjected to high-pressure steam sterilization. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2008-056824 [Patent Document 2] Japanese Patent Application Publication No. 11-080444 [Patent Document 3] Japanese Patent Publication No. 2007-231267 [Patent Document 4] Japanese Patent Publication No. 2021-172812 [Overview of the project] [Problems that the invention aims to solve]

[0004] The object of the present invention is to provide a thermoplastic elastomer composition that is excellent in gas barrier properties and heat resistance. [Means for solving the problem]

[0005] As a result of diligent research, the inventors have found that the above problem can be solved by a specific thermoplastic elastomer composition.

[0006] In other words, the embodiments of the present invention are as follows. [1]. A thermoplastic elastomer composition (excluding those containing a softening agent) comprising (A) 100 parts by mass of isobutylene-isoprene copolymer elastomer, (B) 5 to 60 parts by mass of polypropylene, and (C) 5 to 60 parts by mass of a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound. [2]. The thermoplastic elastomer composition according to item [1], wherein the melting enthalpy of component (B) polypropylene is 50 J / g or more. [3]. The thermoplastic elastomer composition according to item [1] or [2], wherein the above component (C) a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound comprises a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound having a structural unit derived from β-farnesene. [4]. Furthermore, the thermoplastic elastomer composition according to any one of items [1] to [3], further comprising (D) one or more selected from the group consisting of petroleum resins, terpene resins, and rosins, in an amount of 1 to 100 parts by mass per 100 parts by mass of the above component (A) isobutylene-isoprene copolymer elastomer. [5]. Furthermore, the thermoplastic elastomer composition according to any one of items [1] to [4], further comprising (E) a phenol resin crosslinking agent in an amount of 0.5 to 25 parts by mass per 100 parts by mass of the above component (A) isobutylene-isoprene copolymer elastomer. [6]. An article comprising a thermoplastic elastomer composition as described in any one of items [1] to [5]. [Effects of the Invention]

[0007] The thermoplastic elastomer composition of the present invention exhibits excellent gas barrier properties and heat resistance. The preferred thermoplastic elastomer composition of the present invention also exhibits good mechanical properties and flexibility. Therefore, the thermoplastic elastomer composition of the present invention can be suitably used as a material for sealing members such as plugs, gaskets, and packings used in various articles, such as medical plugs. Furthermore, in one embodiment, the thermoplastic elastomer composition of the present invention also exhibits excellent vibration damping characteristics, and can therefore be suitably used as vibration damping members and soundproofing members for automobiles, as well as for vibration damping members and soundproofing members for home appliances such as audio equipment, refrigerators, vacuum cleaners, and air conditioners. [Modes for carrying out the invention]

[0008] In this specification, the term "resin" is used to include resin mixtures containing two or more resins, as well as resin compositions containing components other than resins. The same applies to the term "elastomer."

[0009] In this specification, the term "film" is used interchangeably or interchangeably with the term "sheet." In this specification, the terms "film" and "sheet" are used for materials that can be industrially wound into rolls. The term "plate" is used for materials that cannot be industrially wound into rolls. In this specification, lamination of one layer with another includes both directly laminating those layers and laminating them with one or more other layers, such as an anchor coat, interposed between them.

[0010] In this specification, the term "or more" related to a numerical range is used to mean a certain numerical value or more than a certain numerical value. For example, "20% or more" means 20% or more than 20%. The term "or less" related to a numerical range is used to mean a certain numerical value or less than a certain numerical value. For example, "20% or less" means 20% or less than 20%. Also, the symbol "~" related to a numerical range is used to mean a certain numerical value, more than a certain numerical value and less than another certain numerical value, or another certain numerical value. Here, the other certain numerical value is a numerical value larger than the certain numerical value. For example, "10~90%" means 10%, more than 10% and less than 90%, or 90%. Further, the upper limit and the lower limit of a numerical range can be arbitrarily combined, and an arbitrarily combined embodiment should be construed. For example, from the description such as "usually 10% or more, preferably 20% or more. On the other hand, usually 40% or less, preferably 30% or less." or "usually 10~40%, preferably 20~30%" related to the numerical range of a certain characteristic, it should be construed that the numerical range of that certain characteristic is 10~40%, 20~30%, 10~30%, or 20~40% in one embodiment.

[0011] Except in the examples or unless otherwise specified, all numerical values used in this specification and the claims should be understood as being modified by the term "about". Without attempting to limit the application of the doctrine of equivalents to the claims, each numerical value should be construed in light of the significant figures and by applying ordinary rounding methods.

[0012] In this specification, for terms specifying shapes and geometric conditions, such as terms like parallel, orthogonal, and perpendicular, in addition to their strict meanings, states that are substantially the same should also be included.

[0013] In this specification, when describing "including a certain substance", in one embodiment, it shall be construed as including a certain substance, consisting of a certain substance, or consisting only of a certain substance. For example, from the description "Composition A includes substance a1 and substance a2", in one embodiment, it shall be construed that Composition A includes substance a1 and substance a2, Composition A consists of substance a1 and substance a2, or Composition A consists only of substance a1 and substance a2.

[0014] 1. Thermoplastic elastomer composition: The thermoplastic elastomer composition of the present invention includes (A) an isobutylene - isoprene copolymer elastomer, (B) polypropylene, and (C) a hydrogenated product of a block copolymer of an aromatic vinyl compound and a conjugated diene compound. The thermoplastic elastomer composition of the present invention does not contain a softening agent. In one preferred embodiment, the thermoplastic elastomer composition of the present invention may further include one or more selected from the group consisting of (D) petroleum resins, terpene resins, and rosins. In one preferred embodiment, the thermoplastic elastomer composition of the present invention may further include (E) a phenolic resin cross - linking agent. Hereinafter, each component will be described.

[0015] (A) Isobutylene / isoprene copolymer elastomer: The thermoplastic elastomer composition of the present invention includes (A) an isobutylene - isoprene copolymer elastomer. The (A) isobutylene - isoprene copolymer elastomer is a rubbery amorphous copolymer with a low degree of unsaturation, including a structural unit derived from isobutylene (2 - methylpropene) and a structural unit derived from isoprene (2 - methyl - 1,3 - butadiene). The (A) isobutylene - isoprene copolymer elastomer can be obtained, for example, by polymerizing isobutylene and a small amount of isoprene in methyl chloride using anhydrous aluminum chloride as a catalyst.

[0016] (A) The content of isoprene-derived structural units in the isobutylene-isoprene copolymer elastomer may be preferably 0.5 to 15 mol%, more preferably 0.8 to 5.0 mol%, from the viewpoint of controlling the crosslink density within an appropriate range and improving mechanical properties and moldability, with the total structural units being 100 mol%.

[0017] (A) In one embodiment, the isobutylene-isoprene copolymer elastomer may contain chlorinated isobutylene-isoprene copolymer elastomers and halogenated isobutylene-isoprene copolymer elastomers such as brominated isobutylene-isoprene copolymer elastomers. In this case, the amount of halogen element added may be 5.0% by mass or less, 4.0% by mass or less, 3.0% by mass or less, 0.1 to 2.5% by mass, or 0 to 5.0% by mass, based on 100% by mass of the isobutylene-isoprene copolymer elastomer in one embodiment.

[0018] (A) The isobutylene-isoprene copolymer elastomer may contain constituent units derived from other monomers other than isobutylene and isoprene, to the extent that it does not contradict the purpose of the present invention, such as aromatic divinyl compounds such as divinylbenzene, styrene, aromatic vinyl compounds such as p-methylstyrene, and conjugated dienes other than isoprene such as 1,3-butadiene. In this case, the content of constituent units derived from other monomers may be 3.0 mol% or less, 2.5 mol% or less, 2.0 mol% or less, 1.5 mol% or less, 1.0 mol% or less, 0.1 to 0.5 mol%, or 0 to 3.0 mol%, with the total constituent units being 100 mol%, in one embodiment.

[0019] (A) The isobutylene-isoprene copolymer elastomer may include a modified product obtained by reacting it with an unsaturated compound having a functional group such as a carboxyl group, an acid anhydride group, a hydrosilyl group, an amino group, and an epoxy group, to the extent that it does not contradict the purpose of the present invention. In this case, the amount of the unsaturated compound added may be 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, 0.1 to 1% by mass, or 0 to 20% by mass, based on 100% by mass of the isobutylene-isoprene copolymer elastomer in one embodiment.

[0020] (A) One or more of these can be used as the isobutylene-isoprene copolymer elastomer.

[0021] The amount of (A) isobutylene-isoprene copolymer elastomer blended may be, with the total components of the thermoplastic elastomer composition as 100% by mass, preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more, even more preferably 55% by mass or more, and most preferably 60% by mass or more, depending on the types of components other than the above component (A) isobutylene-isoprene copolymer elastomer. On the other hand, the amount of (A) isobutylene-isoprene copolymer elastomer blended may be, preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and even more preferably 75% by mass or less, from the viewpoint of moldability.

[0022] (B) Polypropylene: The thermoplastic elastomer composition of the present invention comprises (B) polypropylene. (B) polypropylene is a resin that mainly contains structural units derived from propylene and has high crystallinity. Here, "having high crystallinity" means that the enthalpy of fusion (the measurement method will be described later) is 50 J / g or more. Here, "mainly containing structural units derived from propylene" means that the content of structural units derived from propylene is high enough to exhibit the high crystallinity described above. In one embodiment, the content of structural units derived from propylene in (B) polypropylene may be 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 to 100 mol%, with the total structural units being 100 mol%.

[0023] (B) From the viewpoint of heat resistance, the enthalpy of melting of polypropylene is usually 50 J / g or more, preferably 60 J / g or more, more preferably 70 J / g or more, and even more preferably 80 J / g or more. On the other hand, from the viewpoint of flexibility, the enthalpy of melting of polypropylene is usually 120 J / g or less, preferably 115 J / g or less, and more preferably 110 J / g or less.

[0024] (B) From the viewpoint of heat resistance, the melting point of polypropylene is usually 140°C or higher, preferably 145°C or higher, more preferably 150°C or higher, even more preferably 155°C or higher, and even more preferably 160°C or higher. (B) From the viewpoint of heat resistance, a higher melting point is preferable for polypropylene. However, since it is polypropylene, the melting point will probably be around 167°C at most.

[0025] In this specification, (B) the melting point and enthalpy of melting of polypropylene shall be calculated from the DSC second melting curve (the melting curve measured during the final heating process) measured using a differential scanning calorimetry (DSC) device in accordance with JIS K7121-1987, with a program that involves holding at 230°C for 5 minutes, cooling to -50°C at 10°C / min, holding at -50°C for 5 minutes, and heating to 230°C at 10°C / min. In this case, the melting point is the peak top temperature of the melting peak appearing in the above second melting curve. If two or more melting peaks are observed, the peak top temperature of the melting peak with the largest peak top height shall be taken as the melting point. Note that the melting peak appearing in the DSC second melting curve of crystalline polypropylene usually has a long, gradual tail on the low-temperature side; and that the baseline should be drawn so that the straight line extending the high-temperature baseline towards the low-temperature side coincides with the straight line extending the low-temperature baseline towards the high-temperature side, as shown in Figure 1 of JIS K7121-1987, 9. How to Read DTA or DSC Curves.

[0026] (B) The melt mass flow rate, measured in accordance with JIS K7210-1:2014 for polypropylene at 230°C and 21.18N, may be preferably 0.1 to 100 g / 10 min, more preferably 1 to 60 g / 10 min, and even more preferably 2 to 40 g / 10 min, from the viewpoint of moldability.

[0027] (B) Examples of polypropylenes that can be used as polypropylene and have the above-mentioned properties include propylene homopolymers and isotactic polypropylenes such as copolymers (including block copolymers and random copolymers) of propylene with one or more other α-olefins (e.g., ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene).

[0028] (B) One or more of these types of polypropylene may be used.

[0029] (B) The amount of polypropylene added is usually 5 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of (A) isobutylene-isoprene copolymer elastomer, from the viewpoint of heat resistance and moldability. On the other hand, the amount of polypropylene added is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, from the viewpoint of flexibility.

[0030] (C) Hydrogenated block copolymers of aromatic vinyl compounds and conjugated diene compounds: The thermoplastic elastomer composition of the present invention comprises (C) a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound. The hydrogenated block copolymer of (C) an aromatic vinyl compound and a conjugated diene compound contributes to improved flexibility and moldability.

[0031] (C) A hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound is a substance obtained by adding hydrogen to a block polymer containing one or more aromatic vinyl compound polymer segments (c1) and one or more conjugated diene compound polymer segments (c2), thereby converting some or all of the carbon-carbon double bonds in the block polymer into carbon-carbon single bonds. (C) Examples of hydrogenated block copolymers of an aromatic vinyl compound and a conjugated diene compound include those having segment structures such as (c1)-(c2), (c1)-(c2)-(c1), (c2)-(c1)-(c2), (c1)-(c2)-(c1)-(c2), and (c1)-(c2)-(c1)-(c2)-(c1).

[0032] The above aromatic vinyl compounds are polymerizable monomers having polymerizable carbon-carbon double bonds and aromatic rings. Examples of the above aromatic vinyl compounds include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, and p-tertiary butylstyrene. The above aromatic vinyl compounds may preferably contain styrene. One or more of these aromatic vinyl compounds can be used.

[0033] The above-mentioned conjugated diene compound is a polymerizable monomer having a structure in which two carbon-carbon double bonds are connected by one carbon-carbon single bond. Examples of the above-mentioned conjugated diene compounds include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, 7-methyl-3-methyleneocta-1,6-diene (β-myrcene), 3,7,11-trimethyl-1,3,6,10-dodecatetraene (α-farnesene), 7,11-dimethyl-3-methylene-1,6,10-dodecatriene (β-farnesene), and chloroprene (2-chloro-1,3-butadiene). The above-mentioned conjugated diene compound may preferably contain one or more selected from the group consisting of 1,3-butadiene, isoprene, β-myrcene, α-farnesene, and β-farnesene. One or more of these can be used as the above-mentioned conjugated diene compound.

[0034] (c1) The aromatic vinyl compound polymer segment is a polymer segment that mainly contains constituent units derived from the above aromatic vinyl compound. Here, "mainly contains" means that the content of constituent units derived from the above aromatic vinyl compound is more than 50% by mass and 100% by mass or less. From the viewpoint of heat resistance, the content of constituent units derived from the above aromatic vinyl compound may be preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and most preferably 99 to 100% by mass.

[0035] (c1) Examples of aromatic vinyl compound polymer segments include the homopolymer segment of the above aromatic vinyl compound and the copolymer segment of the above aromatic vinyl compound and the above conjugated diene compound. (c1) When there are two or more aromatic vinyl compound polymer segments, they may have the same structure or they may have different structures.

[0036] (c2) The conjugated diene compound polymer segment is a polymer segment that mainly contains structural units derived from the above conjugated diene compound. Here, "mainly contains" means that the content of structural units derived from the above conjugated diene compound is 50 to 100% by mass. From the viewpoint of flexibility, the content of structural units derived from the above conjugated diene compound may be preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and most preferably 99 to 100% by mass.

[0037] (c2) Examples of conjugated diene compound polymer segments include the homopolymer segment of the above conjugated diene compound and the copolymer segment of the above conjugated diene compound and the above aromatic vinyl compound. (c2) When there are two or more conjugated diene compound polymer segments, they may have the same structure or they may have different structures.

[0038] (C) The hydrogenation ratio of the hydrogenated product of the block copolymer of an aromatic vinyl compound and a conjugated diene compound (the ratio of the number of carbon-carbon single bonds formed by hydrogenation to the number of carbon-carbon double bonds in the block copolymer of an aromatic vinyl compound and a conjugated diene compound before hydrogenation) is usually 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and most preferably 90 to 100 mol% from the viewpoint of heat resistance.

[0039] (C) The content of the structural unit derived from the above aromatic vinyl compound in the hydrogenated product of the block copolymer of an aromatic vinyl compound and a conjugated diene compound is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, and still more preferably 15 to 40% by mass from the viewpoints of flexibility and heat resistance.

[0040] (C) The polystyrene-reduced mass average molecular weight (Mw) determined from the differential molecular weight distribution curve (hereinafter sometimes abbreviated as "GPC curve") measured by gel permeation chromatography (hereinafter sometimes abbreviated as "GPC") of the hydrogenated product of the block copolymer of an aromatic vinyl compound and a conjugated diene compound is preferably 1.5×10 4 or more, more preferably 4.5×10 4 or more, and still more preferably 1.5×10 5 or more from the viewpoint of tensile properties. On the other hand, the mass average molecular weight (Mw) is preferably 1.5×10 6 or less, more preferably 1.2×10 6 or less from the viewpoint of moldability.

[0041] (C) The polystyrene-reduced number average molecular weight (Mn) determined from the GPC curve of the hydrogenated product of the block copolymer of an aromatic vinyl compound and a conjugated diene compound is preferably 1.0×10 4 or more, more preferably 3.0×10 4 or more, and still more preferably 1.0×10 5 or more from the viewpoint of tensile properties. On the other hand, the number average molecular weight (Mn) is preferably 1.0×10 6More preferably, it may be 8.0×10 5 or less.

[0042] (C) The GPC measurement of the hydrogenated product of the block copolymer of an aromatic vinyl compound and a conjugated diene compound can be carried out using a high-performance liquid chromatography system "HLC-8320 (trade name)" of Tosoh Corporation (a system including a degasser, a liquid delivery pump, an autosampler, a column oven, and a RI (differential refractive index) detector) as a system, and using two "KF-806L (trade name)" GPC columns, one "KF-802 (trade name)", and one "KF-801 (trade name)" from Shodex Corporation, a total of four columns, connected in series in the order of KF-806L, KF-806L, KF-802, and KF-801 from the upstream side. It can be carried out under the conditions of using tetrahydrofuran (without stabilizer) as the mobile phase, a column temperature of 40°C, a flow rate of 1.0 mL / min, a sample concentration of 1 mg / mL, and a sample injection volume of 100 μL. The elution volume at each retention volume can be determined from the detection amount of the RI detector assuming that there is no molecular weight dependence on the refractive index of the measurement sample. The calibration curve from each retention volume to the polystyrene-equivalent molecular weight can be created using standard polystyrene. At this time, it should be noted that the standard polystyrene to be used should be appropriately selected so that the retention volume of the measurement sample is interpolated into the plot of the calibration curve. For the theory and practice of GPC, reference can be made to reference books such as "Size Exclusion Chromatography High-Performance Liquid Chromatography of Polymers, author: Sadao Mori, first edition, first printing, December 10, 1991" by Kyoritsu Shuppan Co., Ltd., and "Synthetic Polymer Chromatography, editors: Hajime Ohtani, Tatsuya Takasaki (the upper part of '崎' is '立'), first edition, first printing, July 25, 2013" by Ohmsha, Ltd.

[0043] (C) Examples of hydrogenated block copolymers of aromatic vinyl compounds and conjugated diene compounds include styrene-ethylene-butene block copolymer (SEB), styrene-ethylene-propylene block copolymer (SEP), styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer block (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-butadiene-butylene-styrene copolymer (partially hydrogenated styrene-butadiene-styrene copolymer: SBBS), partially hydrogenated styrene-isoprene-styrene copolymer, partially hydrogenated styrene-isoprene-butadiene-styrene copolymer, and hydrogenated styrene-β-farnesene block copolymer.

[0044] (C) In one embodiment, the hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound may include a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound having a constituent unit derived from β-farnesene, such as the hydrogenated styrene-β-farnesene block copolymer. Since β-farnesene is obtained by fermenting sugar from sugarcane, the environmental burden can be reduced. Furthermore, having a constituent unit derived from β-farnesene can increase flexibility.

[0045] (C) One or more of these can be used as hydrogenators for block copolymers of aromatic vinyl compounds and conjugated diene compounds.

[0046] (C) The amount of hydrogenated material added to the block copolymer of the aromatic vinyl compound and the conjugated diene compound may be 5 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of the isobutylene-isoprene copolymer elastomer (A), from the viewpoint of flexibility and moldability. On the other hand, the amount of hydrogenated material added to the block copolymer of the aromatic vinyl compound and the conjugated diene compound (C) may be 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, from the viewpoint of heat resistance.

[0047] (D) Petroleum resin, etc.: In one preferred embodiment, the thermoplastic elastomer composition of the present invention may further contain one or more selected from the group consisting of (D) petroleum resins, terpene resins, and rosins (hereinafter sometimes abbreviated as "(D) petroleum resin, etc."). By including (D) petroleum resin, etc., the vibration damping characteristics of the thermoplastic elastomer composition of the present invention can be improved.

[0048] The above-mentioned petroleum resin is an unsaturated hydrocarbon compound produced by the decomposition of naphtha, etc., and is a polymer of an unsaturated hydrocarbon compound with a large number of carbon atoms (usually around 4 to 20 carbon atoms) (including derivatives such as hydrogenated polymers of the polymer). The above-mentioned unsaturated hydrocarbon compound used as a monomer for the above-mentioned petroleum resin is typically an aliphatic unsaturated hydrocarbon compound, and / or an aromatic unsaturated hydrocarbon compound.

[0049] Examples of the above aliphatic unsaturated hydrocarbon compounds include 1-butene, 2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene, 1-heptene, 2-heptene, 3-heptene, 1,3-pentadiene, cyclopentadiene (cyclopenta-1,3-diene), methylcyclopentadiene, ethylcyclopentadiene, 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), and dicyclopentadiene (tricyclo[5.2.1.02,6]deca-3,8-diene). One or more of these aliphatic unsaturated hydrocarbon compounds can be used.

[0050] Examples of the above aromatic unsaturated hydrocarbon compounds include styrene, α-methylstyrene, β-methylstyrene, 4-methylstyrene, vinylxylene, indene, methylindene, and ethylindene. One or more of these aromatic unsaturated hydrocarbon compounds can be used.

[0051] Examples of the terpene resins mentioned above include polymers of terpenes (hydrocarbons with isoprene as a constituent unit), copolymers of terpenes and phenols, and copolymers of terpenes and monomers copolymerizable with terpenes, such as copolymers of terpenes and styrenes.

[0052] Examples of the above-mentioned rosins include gum rosin, wood rosin, and tall oil rosin, as well as hydrogenated rosin and rosin derivatives such as rosin esters (esters of rosin and polyhydric alcohols).

[0053] (D) Petroleum resins, etc. are preferably hydrogenated from the viewpoint of miscibility with (A) isobutylene-isoprene copolymer elastomer, (B) polypropylene, and (C) propylene-based flexible polyolefin. The hydrogenation rate of (D) petroleum resins, etc. (the ratio of the number of carbon-carbon single bonds converted by hydrogenation to the number of carbon-carbon double bonds in (D) petroleum resins, etc. before hydrogenation) is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 to 100 mol%. The above hydrogenation can be carried out by known methods, for example, by treatment with a hydrogenation catalyst in an inert solvent.

[0054] (D) From the viewpoint of heat resistance, the softening point of petroleum resin, etc. may be preferably 90°C or higher, more preferably 100°C or higher, even more preferably 110°C or higher, even more preferably 120°C or higher, and most preferably 130°C or higher. On the other hand, from the viewpoint of moldability, the softening point of petroleum resin, etc. may be preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. Here, the softening point is measured according to JIS K2207-1996 6.4 Softening point test method (ring and ball method).

[0055] (D) One or more of these types of petroleum resins may be used.

[0056] (D) The amount of petroleum resin etc. is not particularly limited as it is an optional component. If vibration damping characteristics are more important than gas barrier properties, heat resistance, and flexibility, a large amount of (D) petroleum resin etc. may be added. The amount of (D) petroleum resin etc. is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of (A) isobutylene-isoprene copolymer elastomer. On the other hand, the amount of (D) petroleum resin etc. is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less, from the viewpoint of gas barrier properties, heat resistance, and flexibility.

[0057] (E) Phenolic resin crosslinking agent: In one preferred embodiment, the thermoplastic elastomer composition of the present invention may further contain (E) a phenolic resin crosslinking agent. By including (E) the phenolic resin crosslinking agent, (A) the isobutylene-isoprene copolymer elastomer can be crosslinked to improve heat resistance and compression set resistance.

[0058] (E) Phenolic resin crosslinking agents can be obtained by condensing a bifunctional phenol dialcohol compound, or by condensing a phenol or alkyl-substituted phenol with an aldehyde compound, preferably formaldehyde, in an alkaline medium.

[0059] (E) Examples of phenolic resin crosslinking agents include condensates of bifunctional phenol dialcohol compounds such as dimethylolalkylphenol resin, condensates of halogenated bifunctional phenol dialcohol compounds such as halogenated dimethylolalkylphenol resin, condensates of phenol and aldehyde compounds such as phenol formaldehyde resin, halogenated products of said condensates, condensates of alkyl-substituted phenol and aldehyde compounds such as alkylphenol formaldehyde resin, and halogenated alkylphenol formaldehyde resin.

[0060] The above-mentioned dimethylolalkylphenol resin is a condensate of a dimethylolphenol compound having a hydrocarbon group at the p position, preferably a hydrocarbon group having 1 to 15 carbon atoms, more preferably a saturated hydrocarbon group having 1 to 15 carbon atoms, and even more preferably a saturated hydrocarbon group having 1 to 10 carbon atoms.

[0061] The above-mentioned halogenated dimethylolalkylphenol resin is a resin having a structure in which at least one of the terminal alcoholic hydroxyl groups of the above-mentioned dimethylolalkylphenol resin is halogenated with a halogen element such as bromine.

[0062] The alkylphenol formaldehyde resin described above is a condensate of formaldehyde and an alkyl-substituted phenol having a hydrocarbon group at the o, m, or p position, preferably at the p position, preferably a hydrocarbon group having 1 to 15 carbon atoms, more preferably a saturated hydrocarbon group having 1 to 15 carbon atoms, and even more preferably a saturated hydrocarbon group having 1 to 10 carbon atoms.

[0063] The above-mentioned halogenated alkylphenol formaldehyde resin is a resin having a structure in which at least one of the terminal alcoholic hydroxyl groups of the alkylphenol formaldehyde resin is halogenated with a halogen element such as bromine.

[0064] (E) One or more of these can be used as the phenolic resin crosslinking agent.

[0065] (E) The amount of phenolic resin crosslinking agent is optional and is not particularly limited as long as it does not contradict the purpose of the present invention. The amount of (E) phenolic resin crosslinking agent is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, even more preferably 2.0 parts by mass or more, and even more preferably 3.0 parts by mass or more, per 100 parts by mass of (A) isobutylene-isoprene copolymer elastomer, from the viewpoint of reliably obtaining its effect. On the other hand, the amount of (E) phenolic resin crosslinking agent is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 12 parts by mass or less, and most preferably 9 parts by mass or less, from the viewpoint of moldability.

[0066] (F) Crosslinking accelerator: (E) When a phenolic resin crosslinking agent is used, the thermoplastic elastomer composition of the present invention may further contain (F) at least one or more crosslinking promoters selected from the group consisting of zinc oxide, magnesium oxide, and stannous chloride in one preferred embodiment. (E) The crosslinking function of the phenolic resin crosslinking agent can be expressed more effectively.

[0067] (F) The amount of the crosslinking accelerator is an optional component and is not particularly limited as long as it does not contradict the purpose of the present invention. (F) The amount of the crosslinking accelerator is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of (A) isobutylene-isoprene copolymer elastomer, from the viewpoint of reliably obtaining its effect. On the other hand, (F) the amount of the crosslinking accelerator is preferably 6 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 2 parts by mass or less, from the viewpoint of moldability.

[0068] The thermoplastic elastomer composition of the present invention does not contain a softening agent. In other words, any thermoplastic elastomer composition containing a softening agent is excluded from the thermoplastic elastomer composition of the present invention. Therefore, the thermoplastic elastomer composition of the present invention fundamentally solves the problem of softening agents bleeding out due to high temperature and prolonged use.

[0069] In this specification, the term "softener" is used to include not only substances used to soften rubber, but also substances used to soften polyvinyl chloride, polyurethane, and other materials (commonly called "plasticizers"). Known substances used to soften rubber include mineral oils (hydrocarbon compounds derived from petroleum, etc.) such as paraffin oil, naphthenic oil, and aromatic oil, as well as synthetic oils (synthetic hydrocarbon compounds) such as hydrogenated polyisobutylene, polyisobutylene, and polybutene. Known substances used to soften polyvinyl chloride, polyurethane, and other materials include esters of polycarboxylic acids such as di(2-ethylhexyl) phthalate and saturated aliphatic alcohols, polyester plasticizers of polycarboxylic acids and polyols, epoxidized oils such as epoxidized soybean oil, higher alcohols such as oleyl alcohol and stearyl alcohol, phosphate esters, and sulfonic acid esters.

[0070] Here, "does not contain" a softening agent means that it does not contain a significant amount that functions as a softening agent. In the art of thermoplastic elastomer compositions, a significant amount that functions as a softening agent is usually 1 part by mass or more per 100 parts by mass of elastomer. Therefore, "does not contain a softening agent" can also be rephrased as the amount of softening agent blended being usually less than 1 part by mass, preferably 0.1 parts by mass or less, more preferably 0.01 parts by mass or less, and even more preferably 0 to 0.001 parts by mass, per 100 parts by mass of (A) isobutylene-isoprene copolymer.

[0071] The thermoplastic elastomer composition of the present invention may optionally contain any components other than the above components (A) to (F), to the extent that it does not contradict the purpose of the present invention.

[0072] Examples of the above optional components include (A) isobutylene-isoprene copolymer elastomers, (B) polypropylene, (C) hydrogenated block copolymers of aromatic vinyl compounds and conjugated diene compounds, and (D) other thermoplastic resins or thermoplastic elastomers other than petroleum resins, (E) phenolic resin crosslinking agents, and (F) other crosslinking agents or crosslinking accelerators other than crosslinking accelerators, as well as fillers, additives, colorants, and flame retardants.

[0073] Examples of the above-mentioned other thermoplastic resins or thermoplastic elastomers include (B) ethylene-α-olefin-non-conjugated polyene copolymer elastomers, polyethylene, (C) propylene polymers other than polypropylene, and copolymers of aromatic vinyl compounds and conjugated diene compounds other than hydrogenated block copolymers of aromatic vinyl compounds and conjugated diene compounds.

[0074] Examples of the above-mentioned other crosslinking agents or crosslinking accelerators include silicone resin crosslinking agents such as methylhydrogen polysiloxane and alkylmethylpolysiloxane; sulfur compounds, maleimide resin crosslinking agents, and organic peroxides such as 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0075] Examples of the above-mentioned fillers include inorganic fillers such as talc, calcium carbonate, silica (silicon dioxide), mica, clay, hydrotalcite, and zeolite; and organic fillers such as cross-linked acrylic resin particles.

[0076] Examples of the above additives include weathering agents such as anti-aging agents, light stabilizers, and ultraviolet absorbers; antioxidants such as hindered phenol antioxidants, phosphite antioxidants, thioether antioxidants, and amine antioxidants; lubricants such as acid amides, fatty acids, fatty acid esters, fatty acid metal salts, waxes such as polyethylene wax, modified waxes such as modified polyethylene wax, silicone oil, and modified silicone oil; nucleating agents such as aromatic metal phosphate salts and gelols; antistatic agents such as glycerin fatty acid esters; and hydrolysis inhibitors, mold release agents, processing aids, and anti-contamination agents.

[0077] Examples of the above-mentioned colorants include inorganic colorants such as titanium dioxide (titania), red iron oxide (ferric oxide), ultramarine (ultramarine blue), and carbon black; and organic colorants such as aniline black, quinacridone red, isoindolinone yellow, and phthalocyanine blue.

[0078] Examples of the above-mentioned flame retardants include antimony-based flame retardants, halogen-based flame retardants, metal hydroxides, zinc-based flame retardants, organophosphate ester-based flame retardants, and nitrogen-containing compound-based flame retardants.

[0079] As the optional components mentioned above, one or more of these may be used.

[0080] When using the above optional components, the amount of such components is not particularly limited, as they are optional components, as long as it does not contradict the purpose of the present invention. When using the above optional components, the amount of such components may be 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, 3 parts by mass or less, 1 part by mass or less, 0 to 0.5 parts by mass, or approximately 0.01 to 50 parts by mass, per 100 parts by mass of (A) isobutylene-isoprene copolymer elastomer, in one embodiment.

[0081] In one embodiment, the thermoplastic elastomer composition of the present invention may not contain any one or more of the above-mentioned optional components.

[0082] In this specification, "not containing any of the above optional components" means that the component is not intentionally included. In the art of thermoplastic elastomer compositions, when an optional component is intentionally included, it is usually added in an amount of 0.01 parts by mass or more per 100 parts by mass of elastomer. Therefore, "not containing any of the above optional components" can also be rephrased as the content of the component being less than 0.01 parts by mass, preferably 0.001 parts by mass or less, and more preferably 0 to 0.0001 parts by mass, per 100 parts by mass of (A) isobutylene-isoprene copolymer elastomer.

[0083] 2. Manufacturing method: The thermoplastic elastomer composition of the present invention can be obtained by using any melt kneader to simultaneously or in any order introduce components (A) to (C) and any optional components to be used, and melt kneading, preferably at a resin temperature of 180 to 240°C. The kneading time is preferably 1 minute or more, more preferably 3 to 20 minutes, and even more preferably 5 to 10 minutes.

[0084] Examples of the above-mentioned melting and mixing machines include batch mixers such as pressure kneaders and mixers; extrusion mixers such as single-screw extruders, co-rotating twin-screw extruders, and opposite-rotating twin-screw extruders; and calender roll mixers. These may be used in any combination.

[0085] The resulting thermoplastic elastomer composition can be pelletized by any method and then molded into any article by any molding method. Pelletization can be carried out by methods such as hot cutting, strand cutting, and underwater cutting.

[0086] Alternatively, the obtained thermoplastic elastomer composition may be used directly for molding (without going through the pelletizing process).

[0087] 3. Goods: The articles of the present invention include the thermoplastic elastomer composition of the present invention. The articles of the present invention can be obtained by using the thermoplastic elastomer composition of the present invention and molding it into a desired shape by any molding method. Examples of such molding methods include injection molding, extrusion molding, blow molding, press molding, compression molding, and methods combining two or more of these.

[0088] Examples of articles of the present invention include medical articles such as syringes and medical containers, food packaging articles such as beverage containers, printer articles such as ink cartridges and toner cartridges, sealing members such as stoppers, gaskets and packings used in these articles, vibration damping members and soundproofing members for automobiles, and vibration damping members and soundproofing members for home appliances such as audio equipment, refrigerators, vacuum cleaners and air conditioners. [Examples]

[0089] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0090] Measurement method The following tests (a) to (g) were performed after conditioning the test specimens for at least 16 hours in an environment of 23±2℃ and 50±10% humidity, and then under the same temperature and humidity conditions unless otherwise specified.

[0091] (i) Durometer hardness (Type A): In accordance with JIS K6253-2012, a 6.3 mm thick press sheet made using a thermoplastic elastomer composition was used as a test specimen, and the 15-second value of the durometer hardness (Type A) was measured. In the table, durometer hardness (Type A) is indicated as "Hardness A".

[0092] (b) Tensile properties: In accordance with JIS K6251:2017, a thermoplastic elastomer composition was used, and an injection molding machine with a clamping pressure of 120 tons was used. Under the following conditions, the molding temperature was 220°C, the mold temperature was 30°C, the injection speed was 55 mm / sec, the injection pressure was 140 MPa, the holding pressure was 40 MPa, the injection time was 5 seconds, and the cooling time was 20 seconds. A dumbbell-shaped No. 3 test specimen was punched out from a sheet measuring 130 mm in length, 130 mm in width, and 2 mm in thickness. Tensile tests were performed at a test speed of 500 mm / min, and the tensile fracture stress (unit: MPa), 100% strain tensile stress (unit: MPa), and tensile fracture strain (unit: %) were calculated from the obtained stress-strain curve. In the table, the 100% strain tensile stress is indicated as "100% modulus".

[0093] (h) Compression set: In accordance with JIS K6262-2003, test specimens were punched out from a 6.3 mm thick press sheet made using a thermoplastic elastomer composition, and the compression set (in %) was measured under the conditions of 25% compression deformation, a temperature of 120°C, and 22 hours.

[0094] (ii) Gas barrier properties: Using the GTR-20XART (product name) differential pressure type permeability measuring device from GTR Tech Co., Ltd., and following the device's instruction manual and JIS K7126-1:2006 Plastics - Films and Sheets - Gas Permeability Test Method Part 1: Differential Pressure Method, a thermoplastic elastomer composition was used, and an injection molding machine with a clamping pressure of 120 tons was used to injection mold the material under the following conditions: molding temperature 220°C, mold temperature 30°C, injection speed 55 mm / sec, injection pressure 140 MPa, holding pressure 40 MPa, injection time 5 seconds, and cooling time 20 seconds. A sheet measuring 130 mm in length, 130 mm in width, and 2 mm in thickness was punched out as a sample, and the oxygen permeability (unit: cm) was measured under test conditions of 40°C and 90% relative humidity. 3 / (m 2 (day·atm), and moisture permeability (unit: g / (m) 2 The following measurements were taken: The amount of oxygen permeating was measured according to Annex 2 (gas chromatography method) of the above JIS standard. The oxygen partial pressure on the high-pressure side (supply side) was set to 71.02 cmHg (94.69 kPa).

[0095] Raw materials used (A) Isobutylene / isoprene copolymer elastomer (A-1) Butyl rubber "Butyl 268 (product name)" from Nippon Butyl Co., Ltd.

[0096] (B) Polypropylene: (B-1) Propylene homopolymer "PM900A (product name)" manufactured by Sun Allomer Co., Ltd., melt mass flow rate (temperature 230℃, load 21.18N) 30g / 10min, melting point 163℃, enthalpy of fusion 106J / g. (B-2) BC3HF (trade name), a block copolymer of propylene and ethylene from Nippon Polypropylene Co., Ltd., melt mass flow rate (temperature 230℃, load 21.18N) 8.5g / 10min, melting point 164℃, enthalpy of fusion 88J / g.

[0097] (C) Hydrogenated block copolymers of aromatic vinyl compounds and conjugated diene compounds: (C-1) Kuraray Co., Ltd.'s hydrogenated block copolymer of styrene and isoprene (styrene-ethylene-propylene-styrene copolymer) "Septon 2002 (product name)", containing 30% by mass of constituent units derived from styrene. (C-2) Asahi Kasei Corporation's hydrogenated block copolymer of styrene and 1,3-butadiene (styrene-ethylene-butene-styrene copolymer) "ToughTec P1083 (product name)", styrene-derived constituent unit content 20% by mass. (C-3) Kuraray Co., Ltd.'s hydrogenated styrene-β-farnesene block copolymer "Septon BIO SF904 (product name)" contains 21% by mass of constituent units derived from styrene.

[0098] (C'-1) Evonik's amorphous polyolefin "VESTOPLAST708 (trade name)", melt mass flow rate (230℃, 21.18N) is unmeasurable (significantly exceeding 100g / 10min), melting point 81℃, enthalpy of fusion 9J / g.

[0099] (D) Petroleum resin, etc.: (D-1) Idemitsu Kosan Co., Ltd.'s petroleum resin "iMarb P-140 (trade name)," a hydrogenated copolymer of dicyclopentadiene and aromatic unsaturated hydrocarbon compounds. Softening point: 140°C. (D-2) YS Polystar T145 (product name), a terpene phenol resin from Yasuhara Chemical Co., Ltd. Softening point: 145°C.

[0100] (E) Phenolic resin crosslinking agent: (E-1) Taoka Chemical Industry Co., Ltd.'s alkylphenol formaldehyde resin (CAS number 26678-93-3) is the active ingredient in the phenol resin crosslinking agent "Tackirol 202 (product name)," with an active ingredient content of over 90% by mass. The table shows the amount used for "Tackirol 202 (product name)."

[0101] (F) Crosslinking accelerator: (F-1) Anhydrous stannous chloride. CAS number 7772-99-8. (F-2) Two types of zinc oxide as specified in JIS K1410-1995.

[0102] Example 1 A mixture consisting of 100 parts by mass of component (A-1), 26 parts by mass of component (B-1), 23 parts by mass of component (C-1), 6 parts by mass of component (E-1), 0.36 parts by mass of component (F-1), and 0.54 parts by mass of component (F-2) was melt-kneaded using a 20L capacity pressurized kneader under the conditions of a resin temperature of 200°C at discharge and a kneading time of 5 to 10 minutes to obtain a thermoplastic elastomer composition. Tests (a) to (d) above were performed. The results are shown in Table 1.

[0103] Examples 2-12 A thermoplastic elastomer composition was obtained in the same manner as in Example 1, except that the formulation was changed as shown in Table 1 or 2. Tests (a) to (d) described above were performed. The results are shown in Table 1 or 2.

[0104] [Table 1]

[0105] [Table 2]

[0106] The thermoplastic elastomer composition of the present invention was found to have excellent gas barrier properties. Furthermore, the excellent compression set measured at a temperature of 120°C indicated that it also has excellent heat resistance (making it suitable for high-pressure steam sterilization). The preferred thermoplastic elastomer composition of the present invention was also found to have good mechanical properties and flexibility. Therefore, it was considered that the thermoplastic elastomer composition of the present invention can be suitably used as a material for sealing members such as stoppers, gaskets, and packings used in various articles, such as medical stoppers.

[0107] (e) Loss tangent tanδ (an indicator of vibration damping characteristics) For Examples 1, 11, and 12, (e) the loss tangent tanδ was also measured. Using a dynamic viscoelasticity analyzer, a sample measuring 25 mm in length and 10 mm in width, taken from a 1 mm thick press sheet made of a thermoplastic elastomer composition, was set with a chuck distance of 5 mm. The sample was held in tensile mode at a frequency of 1 Hz and at a temperature of -80°C for 1 minute, and then heated to 80°C at a heating rate of 4°C / min. A temperature-loss tangent curve was obtained under these temperature program conditions. Next, the peak top temperature of the loss tangent and its value were calculated from the obtained temperature-loss tangent curve. The same measurement was performed for a frequency of 10 Hz.

[0108] The results for Example 1 were -45°C and 0.49 for the peak-top temperature of the loss tangent at a frequency of 1 Hz, and -32°C and 0.51 for the peak-top temperature of the loss tangent at a frequency of 10 Hz.

[0109] The results for Example 11 were -36°C and 0.43 for the peak-top temperature of the loss tangent at a frequency of 1 Hz, and -24°C and 0.46 for the peak-top temperature of the loss tangent at a frequency of 10 Hz.

[0110] The results for Example 12 were -37°C and 0.44 for the peak-top temperature of the loss tangent at a frequency of 1 Hz, and -25°C and 0.47 for the peak-top temperature of the loss tangent at a frequency of 10 Hz.

[0111] These results show that the thermoplastic elastomer composition of the present invention also has good vibration damping characteristics. Furthermore, it was found that the vibration damping characteristics can be improved by using (D) petroleum resin, etc. Therefore, it was concluded that the thermoplastic elastomer composition of the present invention can be suitably used as vibration damping members and soundproofing members for automobiles, as well as vibration damping members and soundproofing members for home appliances such as audio equipment, refrigerators, vacuum cleaners, and air conditioners. [Brief explanation of the drawing]

[0112] [Figure 1]This is the temperature-loss tangent curve of the thermoplastic elastomer composition of Example 11, measured at a frequency of 1 Hz. [Figure 2] This is the temperature-loss tangent curve of the thermoplastic elastomer composition of Example 11, measured at a frequency of 10 Hz.

Claims

1. (A) Isobutylene / isoprene copolymer elastomer 100 parts by mass, (B) Polypropylene 5 to 60 parts by mass, and (C) Hydrogenated block copolymer of aromatic vinyl compound and conjugated diene compound: 5 to 60 parts by mass including, Thermoplastic elastomer compositions (excluding those containing softening agents).

2. The thermoplastic elastomer composition according to claim 1, wherein the melting enthalpy of component (B) polypropylene is 50 J / g or more.

3. The thermoplastic elastomer composition according to claim 1, wherein the above component (C) hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound comprises a hydrogenated block copolymer of an aromatic vinyl compound and a conjugated diene compound having a structural unit derived from β-farnesene.

4. Furthermore, the thermoplastic elastomer composition according to claim 1, comprising (D) one or more selected from the group consisting of petroleum resins, terpene resins, and rosins, in an amount of 1 to 100 parts by mass per 100 parts by mass of the above component (A) isobutylene / isoprene copolymer elastomer.

5. Furthermore, the thermoplastic elastomer composition according to claim 1, further comprising (E) a phenol resin crosslinking agent in an amount of 0.5 to 25 parts by mass per 100 parts by mass of the above component (A) isobutylene / isoprene copolymer elastomer.

6. An article comprising the thermoplastic elastomer composition according to any one of claims 1 to 5.

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