Thermoplastic elastomer composition for automotive interior member and molded article thereof

Abstract

The present invention provides a thermoplastic elastomer composition simultaneously endowed with excellent fluidity and chemical resistance for use in forming an automobile interior member. This thermoplastic elastomer composition for an automobile interior member contains component (A): a polyolefin, component (B): a hydrogenated block copolymer containing an aromatic vinyl compound unit and a conjugated diene compound unit and having a melt flow rate of 5 g / 10 min or more and 40 g / 10 min or less as measured at 190°C under a load of 2.16 kg with reference to JIS K7210-1 (2014 edition), component (C): a block copolymer and / or a hydrogenated product thereof having at least one block mainly composed of a conjugated diene compound unit and at least one block mainly composed of an aromatic vinyl compound unit, other than component (B), and component (D): a hydrocarbon-based softener for rubber.

Description

Thermoplastic elastomer composition for automobile interior components and molded article thereof

[0001] The present invention relates to a thermoplastic elastomer composition for automobile interior parts and a molded article thereof.

[0002] A thermoplastic elastomer is a material that softens and becomes fluid when heated and exhibits rubber elasticity when cooled. Specifically, during molding, it melts at the processing temperature, allowing it to be easily molded in the same way as well-known thermoplastic resins. However, after molding, at the temperatures at which it is actually used as various materials, it retains physical properties similar to those of crosslinked rubber. As such, thermoplastic elastomers have the same moldability as thermoplastic resins, as well as flexibility and unique rubber elasticity. Furthermore, they are recyclable, and therefore are widely used in a variety of applications, including automotive parts, including automotive interior skins, building components, medical components, electrical wire coatings, and miscellaneous goods.

[0003] In the production of automobile parts, styrene-based thermoplastic elastomers, which are excellent in weather resistance, heat resistance, impact resistance, etc., are used as thermoplastic elastomers, and development is being carried out to meet various market demands. For example, Patent Document 1 proposes a hydrogenated block copolymer composition containing 1% by mass to 95% by mass of a hydrogenated block copolymer containing specific vinyl aromatic compound monomer units and conjugated diene monomer units, and 5% by mass to 99% by mass of at least one olefin-based resin.

[0004] Japanese Patent Application Publication No. 2021-17562

[0005] In recent years, there has been a growing trend toward more luxurious and comfortable interior spaces in automobiles. As a result of this trend, automobile interior components, particularly automobile interior skins such as armrests and console pads, are becoming thinner due to increasing demands for easier molding and lighter parts.

[0006]

[0003] When a thermoplastic elastomer composition is molded, the composition is heated and melted to obtain fluidity, and the fluid molten composition is poured into a mold for molding. However, if the fluidity of the molten composition is insufficient, poor filling of the mold occurs. In thin-wall molding, the molten composition filled into the mold cavity begins to solidify the moment it comes into contact with the mold, making it difficult for the composition to flow into the cavity. Therefore, it is necessary to improve the fluidity of the thermoplastic elastomer composition to prevent poor filling.

[0007] Furthermore, when a molded product made of a thermoplastic elastomer composition comes into contact with another resin molded product, plasticizers contained in the other resin molded product may migrate to the molded product. For example, some protective cases for smartphones are made from resin compositions containing vinyl chloride. If the protective case comes into contact with an armrest or console pad for a long period of time, the plasticizers contained in the resin composition containing vinyl chloride may migrate to the interior skin made of the thermoplastic elastomer composition. As the interior skin becomes thinner, it becomes more susceptible to the effects of plasticizer migration due to its thinness, making it more susceptible to defects such as deformation.

[0008] Therefore, an object of the present invention is to provide a thermoplastic elastomer composition for use in forming automobile interior parts, which has both excellent flowability and chemical resistance.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that a thermoplastic elastomer composition comprising a polyolefin, a hydrogenated block copolymer having a melt flow rate of 5 to 40 g / 10 min and having a block containing aromatic vinyl compound units and conjugated diene compound units, a block copolymer other than the hydrogenated block copolymer and having at least one block mainly composed of conjugated diene compound units and at least one block mainly composed of aromatic vinyl compound units and / or a hydrogenated block copolymer thereof, and a hydrocarbon-based softener for rubber, can achieve both excellent fluidity and chemical resistance, thereby completing the present invention.

[0010] A first aspect of the present invention is a thermoplastic elastomer composition for automotive interior parts, comprising the following components (A), (B), (C), and (D): Component (A): a polyolefin; Component (B): a hydrogenated block copolymer having a block containing an aromatic vinyl compound unit and a conjugated diene compound unit, and having a melt flow rate of 5 g / 10 min to 40 g / 10 min, measured at 190°C under a load of 2.16 kgf in accordance with JIS K7210-1 (2014 edition); Component (C): a block copolymer other than component (B), having at least one block mainly composed of conjugated diene compound units and at least one block mainly composed of aromatic vinyl compound units, and / or a hydrogenated block copolymer thereof; and Component (D): a hydrocarbon-based softener for rubber.

[0011] A second aspect of the present invention is the thermoplastic elastomer composition for automobile interior parts of the first aspect, wherein the weight average molecular weight of the component (C) is 100,000 or more and 1,000,000 or less.

[0012] A third aspect of the present invention is the thermoplastic elastomer composition for automobile interior parts according to the first or second aspect, wherein the content of the component (B) is 5 to 70 parts by mass per 100 parts by mass of the total of the components (A), (B), (C), and (D).

[0013] A fourth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of the first to third aspects, wherein the content of the component (C) is 1 to 50 parts by mass per 100 parts by mass of the total of the components (A), (B), (C), and (D).

[0014] A fifth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of the first to fourth aspects, wherein the content of the component (A) is 3 to 49 parts by mass per 100 parts by mass of the total of the components (A), (B), (C), and (D).

[0015] A sixth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of the first to fifth aspects, wherein the content of the component (D) is 15 to 50 parts by mass per 100 parts by mass of the total of the components (A), (B), (C), and (D).

[0016] A seventh aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of Aspects 1 to 6, wherein the content of component (B) is 5 to 70 parts by mass and the content of component (C) is 1 to 50 parts by mass, relative to a total of 100 parts by mass of component (A), component (B), component (C), and component (D).

[0017] Aspect 8 of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of Aspects 1 to 7, wherein, when the total amount of the component (B) and the component (C) is 100 parts by mass, the ratio of component (B) / component (C) is 5 to 95 / 95 to 5 (mass ratio).

[0018] A ninth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of Aspects 1 to 8, wherein, when the total amount of the component (C) and the component (D) is 100 parts by mass, the ratio of component (C) / component (D) is 20 to 80 / 80 to 20 (mass ratio).

[0019] A tenth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior part according to any one of Aspects 1 to 9, wherein the component (B) has, in addition to the block containing an aromatic vinyl compound unit and a conjugated diene compound unit, a polymer block containing no conjugated diene compound unit and mainly containing an aromatic vinyl compound unit.

[0020] An eleventh aspect of the present invention is the thermoplastic elastomer composition for automobile interior parts according to any one of the first to tenth aspects, wherein the component (A) is polypropylene.

[0021] A twelfth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of Aspects 1 to 11, wherein the component (A) is an ethylene / α-olefin copolymer.

[0022] A thirteenth aspect of the present invention is the thermoplastic elastomer composition for automobile interior parts according to any one of Aspects 1 to 12, further comprising the following component (E), the content of which is 0.01 to 10 parts by mass per 100 parts by mass of the total of component (A), component (B), component (C), and component (D): Component (E): Crosslinking agent

[0023] A fourteenth aspect of the present invention is the thermoplastic elastomer composition for automobile interior parts of Aspect thirteen, further comprising the following component (F), the content of which is 0.05 to 3 parts by mass per 100 parts by mass of the total of component (A), component (B), component (C), and component (D): Component (F): Crosslinking aid.

[0024] A fifteenth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of Aspects 1 to 14, wherein the hardness measured using a Type A durometer with reference to JIS K6253 (2006 edition) is 30 or more and 95 or less.

[0025] A sixteenth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of Aspects 1 to 15, wherein the melt flow rate, as measured with reference to JIS K7210-1, is 45 g / 10 min or more and 200 g / 10 min or less.

[0026] A seventeenth aspect of the present invention is the thermoplastic elastomer composition for an automobile interior member according to any one of Aspects 1 to 16, wherein the thermoplastic elastomer composition for an automobile interior member has a hardness of 35 or more and 87 or less as measured using a Type A durometer with reference to JIS K6253 (2006 edition), and a melt flow rate of 45 g / 10 min or more and 200 g / 10 min or less as measured with reference to JIS K7210-1.

[0027] Aspect 18 of the present invention is an automobile interior part comprising the thermoplastic elastomer composition for an automobile interior part according to any one of Aspects 1 to 17.

[0028] A nineteenth aspect of the present invention is an automobile interior skin comprising the thermoplastic elastomer composition for an automobile interior member according to any one of Aspects 1 to 17.

[0029] According to the present invention, a thermoplastic elastomer composition having flexibility and excellent flowability and chemical resistance can be provided. Therefore, it can be easily molded into thin-walled shapes and is suitable for forming automobile interior components. Among automobile interior components, it is particularly suitable for automobile interior skins.

[0030] The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following description and can be modified as desired without departing from the spirit of the present invention. In this specification, when a numerical value or physical property value is enclosed by "~", the value before and after the "~" is used to include the values ​​before and after the "~" and "~" in the specification. In addition, in this specification, "mass" is synonymous with "weight".

[0031] [Thermoplastic elastomer composition for automotive interior parts] The thermoplastic elastomer composition for automotive interior parts according to an embodiment of the present invention (hereinafter, may be referred to as the "thermoplastic elastomer composition of the present embodiment") contains the following components (A), (B), (C), and (D): Component (A): Polyolefin Component (B): A hydrogenated block copolymer having a block containing an aromatic vinyl compound unit and a conjugated diene compound unit, and having a melt flow rate of 5 g / 10 min to 40 g / 10 min as measured at 190°C under a load of 2.16 kgf in accordance with JIS K7210-1 (2014 edition) Component (C): A block copolymer other than the component (B) having at least one block mainly composed of conjugated diene compound units and at least one block mainly composed of aromatic vinyl compound units, and / or a hydrogenated block copolymer thereof Component (D): A hydrocarbon-based softener for rubber

[0032] Each component will be described below. In this specification, the term "mainly composed of" means that the content of the target monomer unit among the monomer units constituting the target polymer block is 50 mass % or more.

[0033] <Component (A)> The polyolefin of component (A) is not limited as long as it is a polymer containing 50% by mass or more of olefin units, and examples thereof include ethylene-based copolymers such as polypropylene, polyethylene, ethylene-α-olefin copolymer, poly-1-butene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylic acid ester copolymer. However, polypropylene is preferably used due to its excellent heat resistance and moldability. Furthermore, using polypropylene in combination with an ethylene-α-olefin copolymer can impart further flexibility. The thermoplastic elastomer composition of the present embodiment may contain only one type of polyolefin, such as polypropylene, as component (A), or may contain two or more types of polyolefins differing in the type, content, physical properties, etc. of the monomer units contained therein.

[0034] Polypropylene is a polyolefin having a propylene unit content of more than 50% by mass relative to all monomer units.

[0035] The type of polypropylene is not particularly limited, and any of propylene homopolymers, propylene random copolymers, propylene block copolymers, and the like can be used.

[0036] When the polypropylene is a propylene random copolymer, examples of the monomer copolymerized with propylene include ethylene, 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. When the polypropylene is a propylene block copolymer, examples include propylene block copolymers obtained by multi-stage polymerization, more specifically, propylene block copolymers obtained by polymerizing polypropylene in a first stage and polymerizing a propylene-ethylene copolymer in a second stage.

[0037] The content of propylene units in polypropylene is preferably 60% by mass or more, more preferably 75% by mass or more, and even more preferably 90% by mass or more. When the content of propylene units is equal to or more than the above lower limit, heat resistance and rigidity tend to be good. On the other hand, the upper limit of the content of propylene units in polypropylene is not particularly limited and is usually 100% by mass. The content of propylene units in polypropylene can be determined by infrared spectroscopy.

[0038] Methods for producing polypropylene include a slurry method using an inert solvent in the presence of a catalyst, a solution method, a gas-phase method substantially free of solvent, and a bulk polymerization method using the polymerization monomer as the solvent. For example, in the case of a slurry method, the polymerization can be carried out in an inert hydrocarbon or liquid monomer such as n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, cyclohexane, benzene, toluene, or xylene. The polymerization temperature is typically −80 to 150°C, preferably 40 to 120°C. The polymerization pressure is preferably 1 to 60 atmospheres. The molecular weight of the resulting polyolefin can be adjusted with hydrogen or other known molecular weight modifiers. The polymerization can be carried out in a continuous or batch reaction under commonly used conditions. Furthermore, the polymerization reaction can be carried out in a single stage or multiple stages.

[0039] Examples of the catalyst used include Ziegler catalysts and metallocene catalysts. Among these catalysts, metallocene catalysts are preferred. Examples of Ziegler catalysts include, but are not limited to, two-component catalysts consisting of a transition metal component, such as a titanium halide compound (e.g., titanium trichloride, titanium tetrachloride, or trichloroethoxytitanium), a contact product of the titanium halide compound with a magnesium compound (e.g., magnesium halide), and an organometallic component, such as an alkylaluminum compound or its halide, hydride, or alkoxide; and three-component catalysts in which an electron donor compound containing nitrogen, carbon, phosphorus, sulfur, oxygen, silicon, or the like is added to the above components. Examples of metallocene catalysts include, but are not limited to, a catalyst consisting of a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton (a so-called metallocene compound), a cocatalyst capable of reacting with the metallocene compound to activate it to a stable ionic state, and, if necessary, an organoaluminum compound. Any known catalyst can be used. The metallocene compound is preferably a bridged metallocene compound capable of stereoregular polymerization of propylene, more preferably a bridged metallocene compound capable of isoregular polymerization of propylene.

[0040] Commercially available polypropylene products can also be used. For example, commercially available polypropylene can be procured from the manufacturers listed below and can be selected appropriately. Commercially available polypropylene products include Novatec (registered trademark) PP from Japan Polypropylene Corporation, Prime Polypro (registered trademark) from Prime Polymer Co., Ltd., Sumitomo Noblen (registered trademark) from Sumitomo Chemical Co., Ltd., polypropylene block copolymer from SunAllomer Corporation, Moplen (registered trademark) from LyondellBasell, ExxonMobil PP from ExxonMobil, Formolene (registered trademark) from Formosa Plastics, Borealis PP from Borealis, SEETEC PP from LG Chemical, and A. Examples of such polypropylene include ASI POLYPROPYLENE from Schulman, INEOS PP from INEOS Olefins & Polymers, Braskem PP from Braskem, Samsung Total from SAMSUNG TOTAL PETROCHEMICALS, Sabic (registered trademark) PP from Sabic, TOTAL PETROCHEMICALS Polypropylene from TOTAL PETROCHEMICALS, and YUPLENE (registered trademark) from SK Corporation.

[0041] The ethylene / α-olefin copolymer, which is one of the components of the thermoplastic elastomer composition of the present invention, is preferably a copolymer containing ethylene units and α-olefin units having 3 to 20 carbon atoms. The ethylene / α-olefin copolymer can be obtained by copolymerizing at least ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene. Among these, from the viewpoint of imparting mechanical strength and flexibility, α-olefins having 3 to 12 carbon atoms are preferred, with propylene, 1-butene, and 1-octene being more preferred, and 1-octene being particularly preferred.

[0042] The ethylene unit content of the ethylene-α-olefin copolymer is preferably 50% by mass or more and 80% by mass or less, based on the total amount of the ethylene unit content and the α-olefin unit content. A higher ethylene unit content of the ethylene-α-olefin copolymer is preferable from the viewpoint of mechanical strength, and a lower ethylene unit content is preferable from the viewpoint of flexibility. The ethylene unit content of the ethylene-α-olefin copolymer is more preferably 55% by mass or more, and even more preferably 60% by mass or more. Furthermore, the ethylene unit content is more preferably 75% by mass or less. The ethylene unit content and the C3 to C20 α-olefin unit content in component (A) can each be determined by infrared spectroscopy.

[0043] A monomer having an unsaturated bond can be copolymerized with the ethylene-α-olefin copolymer, if necessary. Preferred examples of the monomer having an unsaturated bond include conjugated diolefins such as butadiene and isoprene, non-conjugated diolefins such as 1,4-hexadiene, cyclic diene compounds such as dicyclopentadiene and norbornene derivatives, and acetylenes. Among these, ethylidene norbornene (ENB) and dicyclopentadiene (DCP) are more preferred from the viewpoint of imparting flexibility.

[0044] The ethylene / α-olefin copolymer can be produced using a known polymerization catalyst such as a Ziegler-Natta catalyst, a vanadium catalyst, a metallocene catalyst, etc. The polymerization method is not particularly limited, and can be a liquid phase polymerization method such as a solution polymerization method, a suspension polymerization method, or a bulk polymerization method, a gas phase polymerization method, or any other known polymerization method.

[0045] Ethylene-α-olefin copolymers are also available as commercially available products, such as ENGAGE (registered trademark), INFUSE (registered trademark), and NORDEL (registered trademark) manufactured by Dow Chemical, Vistalon (registered trademark) manufactured by Exxonmobil, EP Rubber manufactured by Eneos Materials, Keltan (registered trademark) and Keltan (registered trademark) Eco manufactured by Arlanxeo, KEP manufactured by Kumho Polychem, Esprene (registered trademark) manufactured by Sumitomo Chemical, and Mitsui EPT (registered trademark), Tafmer P (registered trademark), and Tafmer A (registered trademark) manufactured by Mitsui Chemicals, Inc.

[0046] The weight average molecular weight (Mw) of the polyolefin is preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 200,000 or more from the viewpoint of heat resistance, while the weight average molecular weight of the polyolefin is preferably 1,000,000 or less, more preferably 950,000 or less, and even more preferably 900,000 or less from the viewpoint of moldability.

[0047] Here, the weight average molecular weight (Mw) of polyolefin is the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (hereinafter sometimes abbreviated as "GPC") under the following conditions: (Measurement conditions) Instrument: HLC-8321 GPC / HT manufactured by Tosoh Corporation Column: TSKgel GMHHR-H(20)HT (3 columns) Carrier: 1,2,4-trichlorobenzene Measurement temperature: 140°C Flow rate: 1.0 mL / min Injection amount: 300 μL Concentration: 1 mg / mL Detector: Differential refractometry Molecular weight standard: Standard polystyrene

[0048] The melt flow rate (MFR, measurement temperature 230°C, measurement load 2.16 kgf) of the polyolefin is not particularly limited, but is preferably 0.05 to 2000 g / 10 min. When the melt flow rate (MFR) is within this range, the thermoplastic elastomer composition of this embodiment has excellent moldability, the appearance of automotive interior components formed from the thermoplastic elastomer composition of this embodiment is good, and the mechanical properties and heat resistance can be controlled within desired ranges. The melt flow rate (MFR) of the polyolefin is more preferably 0.1 g / 10 min or more, even more preferably 1 g / 10 min or more, and more preferably 500 g / 10 min or less, even more preferably 200 g / 10 min or less. The melt flow rate of the polyolefin is measured with reference to JIS K7210-1 (2014 edition) under conditions of a measurement temperature of 230°C and a measurement load of 2.16 kgf.

[0049] When an ethylene-α-olefin copolymer is used as the polyolefin, the melt flow rate (MFR) of the ethylene-α-olefin copolymer is preferably 0.1 to 20 g / 10 min, more preferably 0.3 to 10 g / 10 min. By setting the MFR within the above range, a thermoplastic elastomer composition having an excellent balance of fluidity and mechanical strength can be obtained. The melt flow rate (MFR) of the ethylene-α-olefin copolymer is measured in accordance with JIS K7210-1 under conditions of a measurement temperature of 190°C and a measurement load of 2.16 kg. The density of the ethylene-α-olefin copolymer is preferably 0.8 to 0.9 g / cm. ３ It is preferable that:

[0050] <Component (B)> Component (B) is a hydrogenated product of a block copolymer (hereinafter, sometimes referred to as a "first hydrogenated block copolymer") having a block containing an aromatic vinyl compound unit and a conjugated diene compound unit (hereinafter, sometimes referred to as a "block P"), and has a melt flow rate of 5 g / 10 min or more and 40 g / 10 min or less, measured at 190°C under a load of 2.16 kgf in accordance with JIS K7210-1 (2014 edition).

[0051] The hydrogenated product of the block copolymer having the block P (first hydrogenated block copolymer) is a block copolymer obtained by subjecting the block copolymer having the block P to a hydrogenation treatment, thereby hydrogenating some or all of the conjugated diene compound units in the block copolymer.

[0052] The first hydrogenated block copolymer of component (B) can improve the flowability and chemical resistance of the thermoplastic elastomer composition, thereby facilitating thin-wall molding from the thermoplastic elastomer composition and, when a molded article of the thermoplastic elastomer composition comes into contact with another resin molded article and liquid components such as plasticizers contained in the other resin molded article migrate to the molded article, the liquid components can be prevented from being absorbed into the molded article.

[0053] The aromatic vinyl compound constituting the aromatic vinyl compound unit is not particularly limited, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. Among these, from the viewpoints of availability and productivity, styrene, α-methylstyrene, and p-methylstyrene are preferably used. Styrene is more preferred. The aromatic vinyl compound unit contained in block P may contain only one type of aromatic vinyl compound unit, or may contain two or more types of aromatic vinyl compound units.

[0054] The conjugated diene compound constituting the conjugated diene compound unit is a diolefin having a pair of conjugated double bonds, and is not particularly limited, and examples thereof include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferably used from the viewpoint of productivity. 1,3-butadiene is more preferred. The conjugated diene compound unit contained in block P may be only one type of conjugated diene compound unit, or may contain two or more types of conjugated diene compound units.

[0055] Block P may contain a monomer unit other than an aromatic vinyl compound unit and a conjugated diene compound unit. Examples of compounds constituting the monomer units that may be contained in block P include acrylic acid derivatives and methacrylic acid derivatives. From the viewpoint of flexibility, block P is preferably composed of an aromatic vinyl compound unit and a conjugated diene compound unit.

[0056] The content of aromatic vinyl compound units in block P is preferably 30% by mass or more, more preferably 45% by mass or more, and is preferably 79% by mass or less, more preferably 70% by mass or less, i.e., the content of aromatic vinyl compound units in block P is preferably in the range of 30 to 79% by mass.

[0057] The content of the conjugated diene compound units in the block P is preferably 21% by mass or more, more preferably 30% by mass or more, and is preferably 70% by mass or less, more preferably 55% by mass or less, i.e., the content of the conjugated diene compound units in the block P is preferably in the range of 21 to 70% by mass.

[0058] The mass ratio of the aromatic vinyl compound units to the conjugated diene compound units in the block P is preferably in the range of 1:0.21 to 1:2.3, more preferably 1:0.25 to 1:1.8, where 1:0.21 is the aromatic vinyl compound unit and 1:2.3 is the conjugated diene compound unit.

[0059] The block P is the polymer block described above. The block copolymer may contain only one type of block P, and when the block copolymer contains a plurality of blocks P, the compound units thereof may be the same or different.

[0060] A block copolymer having a block P contains the above-described block P and a polymer block or monomer unit other than the block P. In particular, the block copolymer preferably contains a block P and a polymer block other than the block P. The bonding form of each block unit and / or monomer unit is not particularly limited, and the block copolymer having a block P may be linear, branched, radial, or the like.

[0061] Examples of polymer blocks other than block P include a polymer block containing no conjugated diene compound units and mainly composed of aromatic vinyl compound units (hereinafter, sometimes referred to as "block S").

[0062] Examples of the aromatic vinyl compound constituting the aromatic vinyl compound unit contained in block S include the aromatic vinyl compounds described above, and the same applies to preferred examples. The aromatic vinyl compound unit contained in block S may contain only one type of aromatic vinyl compound unit, or may contain two or more types of aromatic vinyl compound units.

[0063] The content of aromatic vinyl compound units in block S is 50% by mass or more, and from the viewpoint of thermal stability, it is more preferably 80% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass. That is, the content of aromatic vinyl compound units in block S is preferably in the range of 50 to 100% by mass.

[0064] Examples of the monomer units other than aromatic vinyl compound units contained in block S include monomer units derived from compounds such as acrylonitrile, methacrylic acid esters, etc. The monomer units other than aromatic vinyl compound units may be of one type only, or may contain two or more types.

[0065] Examples of the monomer units that may be contained in the block copolymer having the block P include monomer units derived from aromatic vinyl compounds and the like.

[0066] The content of block P in the first hydrogenated block copolymer is preferably in the range of 60 to 99% by mass. When the content of block P is 60% by mass or more, the chemical resistance of the thermoplastic elastomer composition can be improved and the effects of the present invention can be easily achieved. When the content of block P is 99% by mass or less, it is easy to achieve both mechanical strength and flexibility while suppressing bleed-out. The content of block P in the first hydrogenated block copolymer is more preferably 70% by mass or more, even more preferably 80% by mass or more, and more preferably 97% by mass or less, even more preferably 95% by mass or less.

[0067] The first hydrogenated block copolymer, component (B), is obtained by obtaining a block copolymer having block P and then hydrogenating the obtained block copolymer. Examples of methods for producing the first hydrogenated block copolymer include known polymerization methods. For example, batch polymerization, continuous polymerization, and the like can be used.

[0068] The hydrogenation rate of the first hydrogenated block copolymer is preferably 20% or more from the viewpoints of light resistance and chemical resistance. The hydrogenation rate is more preferably 50% or more, even more preferably 85% or more, and even more preferably 92% or more. Since a higher hydrogenation rate is preferable, there is no upper limit, and the hydrogenation rate is 100% or less.

[0069] The melt flow rate (MFR, measured at 190°C and under a load of 2.16 kgf) of the first hydrogenated block copolymer is 5 g / 10 min or more and 40 g / 10 min or less. A melt flow rate (MFR) of 5 g / 10 min or more improves the fluidity of the thermoplastic elastomer composition of this embodiment, facilitating the molding of thin-walled articles. A melt flow rate of 40 g / 10 min or less helps to prevent flash formation during molding of the thermoplastic elastomer composition of this embodiment. The melt flow rate of the first hydrogenated block copolymer is preferably 7 g / 10 min or more, more preferably 10 g / 10 min or more, and even more preferably 15 g / 10 min or more. It is also preferably 35 g / 10 min or less, more preferably 30 g / 10 min or less, and even more preferably 28 g / 10 min or less.

[0070] The melt flow rate (MFR) of the first hydrogenated block copolymer is measured under conditions of 190°C and a load of 2.16 kgf with reference to JIS K7210-1 (2014 edition).

[0071] Specific examples of the first hydrogenated block copolymer used in this embodiment include a hydrogenated product of a styrene-butadiene-styrene block copolymer and a hydrogenated product of a styrene-isoprene-styrene block copolymer.

[0072] The first hydrogenated block copolymer may be a commercially available product. Examples of commercially available first hydrogenated block copolymers include "S.O.E (registered trademark)" manufactured by Asahi Kasei Corporation.

[0073] The thermoplastic elastomer composition of the present embodiment may contain one type of first hydrogenated block copolymer alone, or two or more types thereof in combination.

[0074] <Component (C)> Component (C) is a block copolymer and / or a hydrogenated product thereof (hereinafter sometimes referred to as a "second (hydrogenated) block copolymer") having at least one block mainly composed of conjugated diene compound units (hereinafter sometimes referred to as a "block Q") and at least one block mainly composed of aromatic vinyl compound units (hereinafter sometimes referred to as a "block R"). However, component (C) does not include the first hydrogenated block copolymer, which is component (B). Component (C) has a high affinity for softeners such as oil, and by including component (C) in the thermoplastic elastomer composition of this embodiment, the flexibility of the thermoplastic elastomer composition can be increased.

[0075] Examples of the conjugated diene compound constituting block Q include the same conjugated diene compounds as those exemplified for component (B) above, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferably used from the viewpoint of productivity. 1,3-butadiene is more preferred. Block Q may be composed of one type of conjugated diene compound unit, or may be composed of two or more types of conjugated diene compound units.

[0076] Furthermore, the block Q may contain a monomer unit other than a conjugated diene compound unit. Examples of the monomer unit other than a conjugated diene compound unit include a monomer unit derived from a compound such as butylene, isobutylene, or 1,4-hexadiene. The block Q may contain only one type of monomer unit other than a conjugated diene compound unit, or may contain two or more types of monomer units other than a conjugated diene compound unit.

[0077] The content of the conjugated diene compound units in the block Q is 50% by mass or more, and from the viewpoint of flexibility, it is more preferably 80% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass. That is, the content of the conjugated diene compound units in the block Q is preferably in the range of 50 to 100% by mass.

[0078] Examples of aromatic vinyl compounds constituting block R include the same aromatic vinyl compounds as those exemplified for component (B) above, such as styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. Among these, from the viewpoints of availability and productivity, styrene, α-methylstyrene, and p-methylstyrene are preferably used. Styrene is more preferred. Block R may be composed of one type of aromatic vinyl compound unit, or may be composed of two or more types of aromatic vinyl compound units.

[0079] Furthermore, the block R may contain a monomer unit other than the vinyl aromatic compound unit. Examples of the monomer unit other than the vinyl aromatic compound unit include a monomer unit derived from a compound such as acrylonitrile or a methacrylic acid ester. The monomer unit other than the vinyl aromatic compound unit may be of one type only, or may contain two or more types.

[0080] The content of the vinyl aromatic compound units in the block R is 50% by mass or more, and from the viewpoint of thermal stability, it is more preferably 80% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass. That is, the content of the vinyl aromatic compound units in the block R is preferably in the range of 50 to 100% by mass.

[0081] The block copolymer having at least one block Q and one block R may be linear, branched, radial, or the like, but is preferably a block copolymer represented by the following formula (I) or formula (II): (QR) ｎ(I) R-(QR) ｎ (II) (In formula (I) and formula (II), Q represents a block Q, R represents a block R, and n represents an integer of 1 to 5.)

[0082] In the above formulas (I) and (II), when a plurality of blocks Q and a plurality of blocks R are present, the compound units thereof may be the same or different.

[0083] From the viewpoint of rubber elasticity of the composition, component (C) used in the present embodiment is more preferably a block copolymer represented by formula (II), further preferably a block copolymer represented by formula (II) in which n is 1 to 3, particularly preferably a block copolymer represented by formula (II) in which n is 1 to 2, and most preferably a block copolymer represented by formula (II) in which n is 1.

[0084] Component (C) contained in the thermoplastic elastomer composition of this embodiment may be a hydrogenated product of a block copolymer having at least one block Q and one block R. The hydrogenated product is preferably a hydrogenated product of a block copolymer represented by formula (I) or formula (II) above, more preferably a hydrogenated product of a block copolymer represented by formula (II), still more preferably a hydrogenated product of a block copolymer represented by formula (II) in which n is 1 to 3, particularly preferably a hydrogenated product of a block copolymer represented by formula (II) in which n is 1 to 2, and most preferably a hydrogenated product of a block copolymer represented by formula (II) in which n is 1.

[0085] The content of block Q in the second (hydrogenated) block copolymer, component (C), is preferably in the range of 30 to 95% by mass. A block Q content of 30% by mass or more can improve the flexibility of the composition while suppressing bleed-out, while a block Q content of 95% by mass or less can easily improve the mechanical strength. The content of block Q in the second (hydrogenated) block copolymer is more preferably 40% by mass or more, even more preferably 50% by mass or more, and more preferably 90% by mass or less, even more preferably 85% by mass or less.

[0086] The proportion of block R in the second (hydrogenated) block copolymer is preferably in the range of 5 to 70% by mass. When the proportion of block R is 5% by mass or more, mechanical strength can be improved, and when it is 70% by mass or less, it is easy to achieve both suppression of bleed-out and flexibility. The proportion of block R in the second (hydrogenated) block copolymer is more preferably 10% by mass or more, even more preferably 15% by mass or more, and more preferably 60% by mass or less, even more preferably 50% by mass or less. Note that when the aromatic vinyl compound constituting block R in the second (hydrogenated) block copolymer is a styrene unit, the above-mentioned proportion of block R can be expressed as the styrene unit content.

[0087] The second (hydrogenated) block copolymer can be produced by a known polymerization method, such as batch polymerization or continuous polymerization.

[0088] The weight-average molecular weight (Mw) of the second (hydrogenated) block copolymer, component (C), is preferably 10,000 or more and 1,000,000 or less. When the second (hydrogenated) block copolymer has an Mw of 10,000 or more, heat resistance and mechanical strength can be improved, while when the Mw is 1,000,000 or less, the flowability of the thermoplastic elastomer composition of this embodiment can be improved, resulting in a good molded appearance. The weight-average molecular weight (Mw) of the second (hydrogenated) block copolymer is more preferably 30,000 or more, even more preferably 40,000 or more, and more preferably 800,000 or less, even more preferably 650,000 or less.

[0089] The weight average molecular weight (Mw) of the second (hydrogenated) block copolymer is a weight average molecular weight in terms of polystyrene measured by a GPC method under the following conditions: (Measurement conditions) Instrument: "150C ALC / GPC" manufactured by Japan Millipore Column: Three "AD80M / S" columns manufactured by Showa Denko Detector: Infrared spectrophotometer "MIRANIA" manufactured by FOXBORO Wavelength: 3.42 μm Solvent: o-dichlorobenzene Measurement temperature: 140° C. Flow rate: 1 cm ３ / min Injection volume: 200 microliters Concentration: 2 mg / cm ３ 0.2% by mass of 2,6-di-t-butyl-p-phenol was added as an antioxidant.

[0090] Specific examples of the second (hydrogenated) block copolymer used in this embodiment include a styrene-butadiene-styrene block copolymer and a hydrogenated product thereof, and a styrene-isoprene / butadiene-styrene block copolymer and a hydrogenated product thereof.

[0091] The second (hydrogenated) block copolymer may be a commercially available product, such as Kraton (registered trademark) G manufactured by Kraton Polymers, Septon (registered trademark) manufactured by Kuraray Co., Ltd., Tuftec (registered trademark) and S.O.E. (registered trademark) manufactured by Asahi Kasei Corporation, or TAIPOL (registered trademark) manufactured by TSRC.

[0092] The thermoplastic elastomer composition of the present embodiment may contain one type of second (hydrogenated) block copolymer alone, or two or more types may be used in combination.

[0093] <Component (D)> The hydrocarbon-based softener for rubber of component (D) is effective in improving the flexibility and flowability of the thermoplastic elastomer composition of this embodiment.

[0094] As the hydrocarbon-based softener for rubber, mineral oil-based softeners and synthetic resin-based softeners are preferred because they have a high affinity with component (C), and mineral oil-based softeners are more preferred.

[0095] Mineral oil-based softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons. Those in which 50% or more of the total carbon atoms are derived from paraffinic hydrocarbons are called paraffinic oils, those in which approximately 30-45% of the total carbon atoms are derived from naphthenic hydrocarbons are called naphthenic oils, and those in which 35% or more of the total carbon atoms are derived from aromatic hydrocarbons are called aromatic oils. The hydrocarbon-based softener for rubber used as component (D) may be any one of the above-mentioned softeners or a mixture of multiple types. Of these, paraffinic oils are preferred because of their good color. Examples of synthetic resin-based softeners include polybutene and low-molecular-weight polybutadiene.

[0096] The kinematic viscosity at 40°C of the hydrocarbon-based rubber softener (see JIS K2283) is preferably low in terms of improving the fluidity of the thermoplastic elastomer composition of this embodiment, but is preferably high in terms of preventing fogging and the like. Specifically, the kinematic viscosity is preferably 20 centistokes (cSt) or more, and more preferably 50 centistokes or more. On the other hand, the kinematic viscosity is preferably 800 centistokes or less, and more preferably 600 centistokes or less.

[0097] Hydrocarbon-based rubber softeners are commercially available, such as the "Nippon Oil Polybutene (registered trademark) HV" series manufactured by JX Nippon Oil & Energy Corporation and the "Diana (registered trademark) Process Oil PW" series manufactured by Idemitsu Kosan Co., Ltd., from which an appropriate product can be selected and used.

[0098] The hydrocarbon-based rubber softener of component (D) may be used alone or in any combination and ratio of two or more kinds.

[0099] <Component (E)> The thermoplastic elastomer composition of the present embodiment can be made into a crosslinked thermoplastic elastomer composition by including component (E): a crosslinking agent. Examples of component (E) include organic peroxides, phenolic resins, and other crosslinking agents.

[0100] Specific examples of organic peroxides include di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane and other dialkyl peroxides; t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisopropyl carbonate, 2,5-di Examples of the peroxides include peroxy esters such as methyl-2,5-di(benzoylperoxy)hexane and 2,5-dimethyl-2,5-di(benzoylperoxy)hexyne-3; hydroperoxides such as acetyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide and 2,4-dichlorobenzoyl peroxide; diacyl peroxides such as di-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide and dibenzoyl peroxide; and ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide.

[0101] Specific examples of the phenol resin include non-halogen phenol resins such as alkylphenol formaldehyde, and halogen phenol resins such as brominated alkylphenol formaldehyde.

[0102] <Component (F)> When the thermoplastic elastomer composition of the present embodiment contains component (E): a crosslinking agent, it preferably contains component (F): a crosslinking aid.

[0103] Examples of crosslinking aids include crosslinking aids for organic peroxides such as sulfur, p-quinone dioxime, p-dinitrosobenzene, and 1,3-diphenylguanidine; crosslinking aids for phenolic resins such as stannous chloride anhydride, stannous chloride dihydrate, ferric chloride, chlorinated paraffin, chlorinated polyethylene, chlorosulfonated polyethylene, iron oxide, titanium oxide, magnesium oxide, silicon dioxide, and zinc oxide; polyfunctional vinyl compounds such as divinylbenzene, triallyl cyanurate, triallyl isocyanurate, and diallyl phthalate; and polyfunctional (meth)acrylate compounds such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and allyl (meth)acrylate. In this specification, "(meth)acrylate" is a general term for acrylate or methacrylate.

[0104] <Bundling Proportions> In the thermoplastic elastomer composition of this embodiment, the content of component (A) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the total of components (A) to (D). It is also preferably 49 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less. That is, the content of component (A) is preferably in the range of 3 to 49 parts by mass relative to 100 parts by mass of the total of components (A) to (D). By including the polyolefin component (A) in the above range in the thermoplastic elastomer composition of this embodiment, the effects of adding other components can be fully obtained, while the effects of improving heat resistance and mechanical properties provided by component (A) can be fully obtained.

[0105] The amount of component (B) 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 the total of components (A) to (D), and is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 55 parts by mass or less. That is, per 100 parts by mass of the total of components (A) to (D), the content of component (B) is preferably in the range of 5 to 70 parts by mass. By including the hydrogenated block copolymer of component (B) in the above range, the effects of blending the other components can be fully obtained, and the effect of improving flowability and chemical resistance provided by component (B) can be fully obtained.

[0106] The amount of component (C) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, and particularly preferably 10 parts by mass or more, per 100 parts by mass of the total of components (A) to (D), and is preferably 50 parts by mass or less, more preferably 48 parts by mass or less, and even more preferably 45 parts by mass or less. That is, per 100 parts by mass of the total of components (A) to (D), the content of component (C) is preferably in the range of 1 to 50 parts by mass. By including the (hydrogenated) block copolymer of component (C) in the above range, the effects of blending the other components can be fully obtained, and the effects of improving flexibility, good touch, and scratch resistance provided by component (C) can be fully obtained.

[0107] For a total of 100 parts by mass of components (A) to (D), the amount of component (D) is preferably 15 parts by mass or more, more preferably 18 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 48 parts by mass or less, and even more preferably 45 parts by mass or less. That is, for a total of 100 parts by mass of components (A) to (D), the content of component (D) is preferably in the range of 15 to 50 parts by mass. By including the hydrocarbon-based softener for rubber of component (D) in the above range, the compounding effects of the other components can be fully obtained, and the flexibility and flow-improving effects of component (C) can be fully obtained.

[0108] In the thermoplastic elastomer composition of the present embodiment, the content of component (B) is 5 to 70 parts by mass and the content of component (C) is 1 to 50 parts by mass relative to 100 parts by mass of the total of components (A) to (D), and therefore, the flowability and chemical resistance can be preferably improved while the blending effects of the other components are sufficiently obtained.

[0109] In the thermoplastic elastomer composition of this embodiment, when the total amount of components (B) and (C) is 100 parts by mass, the mass ratio of component (B) / component (C) is preferably 5 to 95 / 95 to 5, more preferably 10 to 90 / 90 to 10, and even more preferably 15 to 85 / 85 to 15. When the content ratio of components (B) to (C) is within the above range, both flexibility and chemical resistance can be achieved.

[0110] Furthermore, in the thermoplastic elastomer composition of this embodiment, when the total amount of components (C) and (D) is 100 parts by mass, the mass ratio of component (C) / component (D) is preferably 20 to 80 / 80 to 20, more preferably 22 to 78 / 78 to 22, and even more preferably 25 to 75 / 75 to 25. When the content ratio of components (C) to (D) is within the above range, the flexibility of the thermoplastic elastomer composition of this embodiment is increased, thereby improving moldability.

[0111] When the thermoplastic elastomer composition of this embodiment contains the cross-linking agent of component (E), the content of component (E) is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the total of components (A), (B), (C), and (D), in order to sufficiently proceed with the cross-linking reaction, while from the viewpoint of controlling the cross-linking reaction, the content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less. That is, the content of component (E) is preferably in the range of 0.01 to 10 parts by mass, relative to 100 parts by mass of the total of components (A) to (D).

[0112] When the thermoplastic elastomer composition of the present embodiment contains the cross-linking aid of component (F), the content of component (F) is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, per 100 parts by mass of the total of components (A), (B), (C), and (D) from the viewpoint of obtaining the effect of using the cross-linking aid, while from the viewpoint of cost, the content is preferably 3 parts by mass or less, more preferably 2 parts by mass or less. That is, the content of component (F) is preferably in the range of 0.05 to 3 parts by mass, per 100 parts by mass of the total of components (A) to (D).

[0113] <Other Components> The thermoplastic elastomer composition of the present embodiment may contain other components (sometimes simply referred to as "other components" in this specification) in addition to components (A) to (F), as necessary, to the extent that the object of the present invention is not impaired. Examples of other components include polymers and elastomers other than components (A) to (C) (sometimes collectively referred to as "other polymers" in this specification), and various additives.

[0114] Examples of other polymers that may be contained in the thermoplastic elastomer composition of this embodiment include polymers such as polyesters, polyamides, styrene polymers (excluding those corresponding to component (B) or component (C) above), acrylic polymers, polycarbonates, polyphenylene ethers, and polyvinyl chloride; styrene elastomers other than component (B) and component (C); polyamide elastomers such as polyamide-polyol copolymers; polyvinyl chloride elastomers and polybutadiene elastomers; hydrogenated products thereof; those modified with acid anhydrides or the like to introduce polar functional groups; and those obtained by grafting, randomly, and / or block copolymerizing other monomers. The other resins listed above may be used alone or in combination of two or more.

[0115] Furthermore, examples of additives that may be contained in the thermoplastic elastomer composition of the present embodiment include molding processing aids such as antioxidants, crystal nucleating agents, and lubricants, ultraviolet absorbers, light stabilizers, hydrolysis resistance improvers, colorants such as pigments and dyes, antistatic agents, conductive agents, reinforcing agents, fillers, plasticizers, mold release agents, and foaming agents.

[0116] It is effective to blend silicone as a lubricant in the thermoplastic elastomer composition of this embodiment. Silicone is a component that imparts abrasion resistance to the thermoplastic elastomer composition and prevents the stickiness that is characteristic of elastomers.

[0117] There are no particular limitations on the type of substituent bonded to the siloxane main chain in the molecular structure of the silicone, but among these, dimethyl silicone (dimethyl polysiloxane), methyl phenyl silicone, or alkyl-modified silicone is preferably used.

[0118] The kinematic viscosity of the silicone (measured at 25°C according to JIS Z8803) is usually 1 centistoke (cSt) or more, preferably 5 centistokes or more, and more preferably 10 centistokes or more, with no particular upper limit. The higher the kinematic viscosity of the silicone, the greater the effect of improving abrasion resistance and scratch resistance, and the lower the kinematic viscosity, the greater the effect of improving stickiness.

[0119] When the thermoplastic elastomer composition of the present invention contains a lubricant such as silicone oil, the content thereof is preferably 0.1 to 15 parts by mass, and more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the total of components (A), (B), (C), and (D). A silicone content of 0.1 part by mass or more is preferred from the viewpoint of improving abrasion resistance, scratch resistance, and stickiness resistance, while a silicone content of 15 parts by mass or less is preferred from the viewpoints of mechanical strength, suppression of bleed-out, etc.

[0120] As the lubricant, in addition to the above-mentioned silicone oil, for example, fatty acid amides, fatty acid metal salts, etc. can be used.

[0121] The other lubricant is preferably contained in an amount ranging from 0.01 to 10 parts by mass per 100 parts by mass of the total of components (A) to (D). If this content is 0.01 part by mass or more, releasability and abrasion resistance can be improved, and if it is 10 parts by mass or less, the stickiness characteristic of lubricants can be suppressed. The content of the other lubricant is more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of the total of components (A) to (D).

[0122] Examples of antioxidants (heat stabilizers) that can be blended include hydroxylamine-based antioxidants, dithiocarbamate-based antioxidants, hindered phenol-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants.

[0123] The hydroxylamine-based antioxidant is preferably an N,N-dialkylhydroxylamine, which is represented by the general formula R ａ R ｂ NOH (in the formula, R ａ and R ｂ and each independently represent alkyl. ａ or R ｂ is a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, or a heptadecyl group. Particularly preferred dialkylhydroxylamines are N,N-dioctadecylhydroxylamine and N,N-dihexadecylhydroxylamine, or a mixture thereof, and examples of commercially available products include "Irganox (registered trademark) 1010" manufactured by BASF.

[0124] As the dithiocarbamate antioxidant, metal salts of dialkyldithiocarbamic acid are preferred, among which nickel dialkyldithiocarbamate is preferred, and nickel dibutyldithiocarbamate is particularly preferred because of its great effect in improving heat aging resistance.

[0125] Known hindered phenol antioxidants can be used, and it is preferable to use those having a molecular weight of 500 or more, such as tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane.

[0126] The sulfur-based antioxidants are compounds containing sulfur, such as thioethers, dithioacid salts, mercaptobenzimidazoles, thiocarbanilides, and thiodipropionate compounds. However, they do not include compounds equivalent to the dithiocarbamate antioxidants. Among these, thiodipropionate compounds are particularly preferred.

[0127] Examples of phosphorus-based antioxidants include phosphorus-containing compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid derivatives, phenylphosphonic acid, polyphosphonates, dialkyl pentaerythritol diphosphites, and dialkyl bisphenol A diphosphites.

[0128] These antioxidants may be used alone or in combination of two or more.

[0129] When the thermoplastic elastomer composition of this embodiment contains an antioxidant, the content of the antioxidant is preferably 0.01 to 5 parts by mass per 100 parts by mass of the total of components (A) to (D). A content of 0.01 part by mass or more is preferred from the viewpoint of improving heat degradation resistance, while a content of 5 parts by mass or less is preferred from the viewpoint of preventing problems such as bleeding and from the viewpoint of the mechanical strength of the composition. The content of the antioxidant is more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the total of components (A) to (D).

[0130] <Method for Producing Thermoplastic Elastomer Composition> The method for producing the thermoplastic elastomer composition of the present embodiment is not particularly limited, and the composition can be produced, for example, by dry-blending components (A) to (D) and, if necessary, components (E), (F), or other components, followed by melt-kneading in accordance with a conventional method.

[0131] The mixing device used in this process is not particularly limited, but examples thereof include kneading devices such as a Banbury mixer, a Labo Plastomill, a single-screw extruder, and a twin-screw extruder. Among these, production by a melt mixing method using an extruder is preferred from the viewpoints of productivity and good kneading properties. The melt temperature during kneading can be set as appropriate, but is usually in the range of 130 to 300°C, and preferably in the range of 150 to 250°C.

[0132] [Physical Properties of Thermoplastic Elastomer Composition] <Duro Hardness A> The thermoplastic elastomer composition of this embodiment preferably has a hardness (Duro Hardness A) of 30 or more and 95 or less, as measured using a Type A durometer in accordance with JIS K6253 (2006 edition). When the Duro Hardness A is 30 or more, it is easy to well control the mechanical strength and heat resistance, and when it is 95 or less, it is easy to have flexibility. The Duro Hardness A of the thermoplastic elastomer composition is more preferably 35 or more, even more preferably 40 or more, and more preferably 92 or less, even more preferably 90 or less, and particularly preferably 87 or less.

[0133] <Melt Flow Rate> The thermoplastic elastomer composition of this embodiment preferably has a melt flow rate (MFR, measured at 230°C and under a load of 2.16 kgf) of 45 g / 10 min or more and 200 g / 10 min or less, as measured in accordance with JIS K7210-1. A melt flow rate (MFR) of 45 g / 10 min or more provides excellent fluidity, thereby preventing mold filling defects and facilitating thin-wall molding. A melt flow rate (MFR) of 200 g / 10 min or less provides excellent fluidity and also helps to prevent flash formation during molding. The melt flow rate (MFR) of the thermoplastic elastomer composition is more preferably 50 g / 10 min or more, even more preferably 55 g / 10 min or more, and more preferably 190 g / 10 min or less, even more preferably 170 g / 10 min or less, and particularly preferably 150 g / 10 min or less.

[0134] The thermoplastic elastomer composition of the present embodiment has a hardness of 35 or more and 87 or less as measured using a Type A durometer in accordance with JIS K6253 (2006 edition), and a melt flow rate of 45 g / 10 min or more and 200 g / 10 min or less as measured in accordance with JIS K7210-1. This allows for both flexibility and flowability, making the composition suitable for thin-wall molding, and enabling the molded article to have the soft feel required for automobile interior components.

[0135] [Automobile Interior Members] The thermoplastic elastomer composition of the present embodiment is suitable for automobile interior members, and is particularly suitable for automobile interior skins. The automobile interior members and automobile interior skins according to the embodiments of the present invention contain the thermoplastic elastomer composition of the present embodiment and are produced, for example, by molding the thermoplastic elastomer composition of the present embodiment. The thermoplastic elastomer composition of the present embodiment can be molded using various molding methods, such as ordinary injection molding and extrusion molding.

[0136] The molding conditions for injection molding the thermoplastic elastomer composition of this embodiment are as follows: The molding temperature is preferably 160 to 250°C, more preferably 170 to 230°C. The injection pressure is preferably 5 to 100 MPa, more preferably 10 to 80 MPa. The mold temperature is preferably 10 to 80°C, more preferably 20 to 60°C.

[0137] An injection-molded article obtained by injection molding the thermoplastic elastomer composition of this embodiment can also be heat-fused to an olefin-based hard resin such as a propylene resin to form a composite molded article, which can be used as an automobile interior member or an automobile interior skin.

[0138] Specific embodiments of the present invention will be described in more detail below using examples, but the present invention is not limited to the following examples as long as the gist of the invention is not exceeded. Note that the values ​​of various production conditions and evaluation results in the following examples represent preferred upper or lower limit values ​​in the embodiments of the present invention, and preferred ranges may be defined by a combination of the above-mentioned upper or lower limit values ​​and the values ​​in the following examples or values ​​between the examples.

[0139] In the following examples and comparative examples, the raw materials used in the preparation of the thermoplastic elastomer compositions and the evaluation methods of the obtained thermoplastic elastomer compositions are as follows.

[0140] [Raw Materials Used] <Component (A)> A-1: ​​"Novatec (registered trademark) PP SA04M" manufactured by Japan Polypropylene Corporation (propylene homopolymer, MFR (JIS K7210-1, 230°C, 2.16 kgf load): 40 g / 10 min) A-2: "ENGAGE (registered trademark) 8842" manufactured by The Dow Chemical Company (ethylene-1-octene copolymer, MFR (JIS K7210-1, 190°C, 2.16 kgf load): 1.0 g / 10 min)

[0141] <Component (B)> B-1: "S.O.E. (registered trademark)-SS S1614" manufactured by Asahi Kasei Corporation (a hydrogenated copolymer of styrene and butadiene having blocks containing styrene units and butadiene units, MFR (JIS K7210-1, 190°C, 2.16 kgf load): 20 g / 10 min)

[0142] <Component (C)> C-1: Kraton (registered trademark) G1633EU manufactured by Kraton Corporation (hydrogenated styrene-butadiene-styrene block copolymer, weight average molecular weight: 443,000, styrene unit content: 30% by mass) C-2: Kraton (registered trademark) G1652MU manufactured by Kraton Corporation (hydrogenated styrene-butadiene-styrene block copolymer, weight average molecular weight: 68,500, styrene unit content: 29% by mass)

[0143] <Component (D)> D-1: "Diana Process Oil PW90" manufactured by Idemitsu Kosan Co., Ltd. (paraffinic oil, kinematic viscosity (40°C): 90 cSt)

[0144] <Component (X): Alternative to Component (B) or Component (C)> X-1: "S.O.E. (registered trademark)-SS S1605" manufactured by Asahi Kasei Corporation (a hydrogenated copolymer of styrene and butadiene having blocks containing styrene units and butadiene units, MFR (JIS K7210, 190°C, 2.16 kgf load): 0.8 g / 10 min)

[0145] <Component (E)> E-1: "Trigonox (registered trademark) 101-40C" manufactured by Kayaku Nouryon Co., Ltd. (a mixture of 40% by mass of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 60% by mass of calcium carbonate)

[0146] <Component (F)> F-1: "DVB-570" manufactured by Nippon Steel Chemical Co., Ltd. (a mixture of 55% by mass of divinylbenzene and 45% by mass of ethylvinylbenzene) F-2: "Taiku" manufactured by Shinryo Corporation (triallyl isocyanurate)

[0147] <Component (G)> G-1: "MB50-001" manufactured by Dow Corning Toray Co., Ltd. (dimethylpolysiloxane masterbatch, dimethylpolysiloxane content: 50% by mass, kinematic viscosity (see JIS Z8803, measured at 25°C): 1,000,000 cSt or more)

[0148] [Evaluation Method] The thermoplastic elastomer compositions in the following Examples and Comparative Examples were evaluated as follows. In the measurement of (2) below, each thermoplastic elastomer composition was injection molded using an in-line screw-type injection molding machine ("IS130" manufactured by Toshiba Machine Co., Ltd.) under conditions of an injection pressure of 50 MPa, a cylinder temperature of 220°C, and a mold temperature of 40°C, to obtain an injection sheet having a thickness of 2 mm, a width of 120 mm, and a length of 120 mm, on which scribe lines were processed in the composition flow direction so that the distance between the scribe lines was 100 mm in the actual mold dimensions, and this injection sheet was evaluated. In the measurement of (3) below, each thermoplastic elastomer composition was injection molded using an in-line screw type injection molding machine ("SE180" manufactured by Sumitomo Heavy Industries, Ltd.) under conditions of an injection pressure of 50 MPa, a cylinder temperature of 220°C, and a mold temperature of 40°C to obtain an injection sheet having a thickness of 1.5 mm, a width of 100 mm, and a length of 350 mm, and this injection sheet was evaluated.

[0149] (1) Melt flow rate (MFR) Measured in accordance with JIS K7210-1 under conditions of a temperature of 230° C. and a load of 2.16 kgf.

[0150] (2) Hardness Using a Type A Durometer (Duro Hardness A) With reference to JIS K6253 (Duro-A) (2006 edition), the hardness after 15 seconds was measured using a Type A durometer.

[0151] (3) Chemical Resistance A sheet molded from polyvinyl chloride (PVC, "Sunplaine FE50MB" manufactured by Mitsubishi Chemical Corporation) was cut to a size of 35 mm x 35 mm and placed on an injection sheet prepared by injection molding each thermoplastic elastomer composition to obtain a test specimen. The test specimen was left standing in a thermostatic chamber at 80°C for 20 hours, and the degree of deformation of the injection sheet made of the thermoplastic elastomer composition was visually confirmed and evaluated according to the following criteria. The less deformation, the better the chemical resistance. The higher the evaluation score, the better the evaluation, and a score of 2 or higher indicates practical use. <Evaluation Criteria> 5: No deformation at all (does not move when pressed with a finger). 4: No deformation observed visually, slight deformation when pressed with a finger. 3: Almost no deformation is visible from the top view of the test specimen, but when viewed from the side, part of the contact surface with the PVC sheet is deformed. 2: Only the contact surface with the PVC sheet is deformed. 1: Not only the contact surface with the PVC sheet but also the surrounding area is deformed. 0: The deformation is so great that the bulged part does not touch the bottom when pressed with a finger.

[0152] Example 1 1.5 parts by mass of component (G-1) (the amount of dimethylpolysiloxane in component (G-1) (actual amount: 50%)) and 0.1 parts by mass of an antioxidant ("Songnox (registered trademark) 1076" manufactured by Songwon Co.) were mixed with a total of 100 parts by mass of 20 parts by mass of component (A-1), 50 parts by mass of component (B-1), 10 parts by mass of component (C-1), and 20 parts by mass of component (D-1). The resulting mixture was melt-kneaded in a twin-screw kneader (cylinder temperature: 180°C to 220°C) to produce pellets of a thermoplastic elastomer composition. The resulting thermoplastic elastomer composition was evaluated according to the above criteria (1) to (3). The evaluation results are shown in Table 1.

[0153] [Examples 2 to 11 and Comparative Examples 1 to 3] Pellets of thermoplastic elastomer compositions were obtained in the same manner as in Example 1, except that the raw material blending amounts were as shown in Table 1. The obtained thermoplastic elastomer compositions were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0154]

[0155] As can be seen from Table 1, the compositions of Examples 1 to 11 had high fluidity and excellent chemical resistance, and both fluidity and chemical resistance were satisfactory. Furthermore, the molded articles (sheets) had flexibility. In contrast, the composition of Comparative Example 1 had low fluidity, Comparative Example 2 had insufficient fluidity and chemical resistance, and Comparative Example 3 had poor chemical resistance. None of the compositions achieved both fluidity and chemical resistance.

[0156] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2024-014060) filed on February 1, 2024, the contents of which are incorporated herein by reference.

[0157] Automobile interior members and automobile interior skins obtained from the thermoplastic elastomer composition of the present invention are excellent in tactile feel, scratch resistance, light resistance, and heat resistance, and are used to enhance the luxury and comfort of automobile interior spaces, and are also suitable for eliminating the need for painting from the viewpoints of reducing environmental load and process steps.

Claims

1. A thermoplastic elastomer composition for automotive interior parts, comprising the following components (A), (B), (C), and (D): Component (A): a polyolefin; Component (B): a hydrogenated block copolymer having a block containing an aromatic vinyl compound unit and a conjugated diene compound unit, and having a melt flow rate of 5 g / 10 min to 40 g / 10 min, measured at 190°C under a load of 2.16 kgf in accordance with JIS K7210-1 (2014 edition); Component (C): a block copolymer other than component (B), having at least one block mainly composed of conjugated diene compound units and at least one block mainly composed of aromatic vinyl compound units, and / or a hydrogenated block copolymer thereof; Component (D): a hydrocarbon-based softener for rubber.

2. The thermoplastic elastomer composition for automobile interior parts according to claim 1, wherein the weight average molecular weight of said component (C) is 100,000 or more and 1,000,000 or less.

3. The thermoplastic elastomer composition for automotive interior parts according to claim 1, wherein the content of component (B) is 5 to 70 parts by mass per 100 parts by mass of the total of components (A), (B), (C), and (D).

4. The thermoplastic elastomer composition for automobile interior parts according to claim 1, wherein the content of component (C) is 1 to 50 parts by mass per 100 parts by mass of the total of components (A), (B), (C), and (D).

5. The thermoplastic elastomer composition for automotive interior parts according to claim 1, wherein the content of component (A) is 3 to 49 parts by mass per 100 parts by mass of the total of components (A), (B), (C), and (D).

6. The thermoplastic elastomer composition for automobile interior parts according to claim 1, wherein the content of component (D) is 15 to 50 parts by mass per 100 parts by mass of the total of components (A), (B), (C), and (D).

7. The thermoplastic elastomer composition for automobile interior parts according to claim 1, wherein the content of component (B) is 5 to 70 parts by mass and the content of component (C) is 1 to 50 parts by mass, relative to a total of 100 parts by mass of components (A), (B), (C), and (D).

8. The thermoplastic elastomer composition for automotive interior parts according to claim 1, wherein the ratio of component (B) / component (C) is 5 to 95 / 95 to 5 (mass ratio) when the total of component (B) and component (C) is 100 parts by mass.

9. The thermoplastic elastomer composition for automotive interior parts according to claim 1, wherein the ratio of component (C) / component (D) is 20 to 80 / 80 to 20 (mass ratio) when the total of component (C) and component (D) is 100 parts by mass.

10. A thermoplastic elastomer composition for automotive interior parts according to claim 1, wherein component (B) has, in addition to the block containing aromatic vinyl compound units and conjugated diene compound units, a polymer block containing no conjugated diene compound units but mainly composed of aromatic vinyl compound units.

11. The thermoplastic elastomer composition for automobile interior parts according to claim 1, which contains polypropylene as component (A).

12. The thermoplastic elastomer composition for automobile interior parts according to claim 11, which contains an ethylene-α-olefin copolymer as component (A).

13. The thermoplastic elastomer composition for automotive interior parts according to claim 1, comprising the following component (E), the content of which is 0.01 to 10 parts by mass per 100 parts by mass of the total of components (A), (B), (C), and (D): Component (E): Crosslinking agent 14. The thermoplastic elastomer composition for automobile interior parts according to claim 13, which contains the following component (F), and the content thereof is 0.05 to 3 parts by mass per 100 parts by mass of the total of component (A), component (B), component (C), and component (D): Component (F): crosslinking coagent 15. A thermoplastic elastomer composition for automotive interior parts according to claim 1, having a hardness of 30 or more and 95 or less as measured using a Type A durometer in accordance with JIS K6253 (2006 edition).

16. The thermoplastic elastomer composition for automobile interior parts according to claim 1, which has a melt flow rate of 45 g / 10 min or more and 200 g / 10 min or less, measured in accordance with JIS K7210-1.

17. The thermoplastic elastomer composition for automotive interior parts according to claim 1, which has a hardness of 35 or more and 87 or less as measured using a Type A durometer in accordance with JIS K6253 (2006 edition), and a melt flow rate of 45 g / 10 min or more and 200 g / 10 min or less as measured in accordance with JIS K7210-1.

18. An automobile interior part comprising the thermoplastic elastomer composition for automobile interior parts according to any one of claims 1 to 17.

19. An automobile interior skin comprising the thermoplastic elastomer composition for automobile interior parts according to any one of claims 1 to 17.

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