Styrenic thermoplastic elastomer composition and molded body of the same

Abstract

To provide a styrenic thermoplastic elastomer composition which has flexibility, and can suppress occurrence of cracks when making a composite with a hard resin.SOLUTION: A styrenic thermoplastic elastomer composition contains a component (A): polyolefin and a component (B): styrenic rubber, wherein when the styrenic thermoplastic elastomer composition is injection-molded under the conditions of an injection pressure of 50 MPa, a cylinder temperature of 220°C and a mold temperature of 40°C, and when a sheet with a thickness of 2 mm, a width of 120 mm and a length of 120 mm in which marking-off lines are processed so that a distance between the marking-off lines is 100 mm in actual size in a composition flow direction is obtained, a molding shrinkage ratio of the sheet is less than 10.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a styrene-based thermoplastic elastomer composition and a molded article thereof. [Background technology]

[0002] Thermoplastic elastomers are materials that soften and become fluid when heated and acquire rubber elasticity when cooled. Thermoplastic elastomers are excellent in moldability, flexibility, rubber elasticity, abrasion resistance, and hygiene. They are also recyclable, and are therefore used in a variety of applications, including grips and skins for automotive parts, construction parts, medical parts, and general merchandise. In particular, thermoplastic elastomer molded articles are often embedded in or fused to hard resins to create laminates, thereby imparting flexibility, rubber elasticity, and slip resistance to hard resins.

[0003] A typical example of such a thermoplastic elastomer is a styrene-based thermoplastic elastomer, and various types have been proposed so far.

[0004] For example, Patent Document 1 proposes a thermoplastic elastomer composition having an A hardness of 90 or less, which contains a styrene elastomer A having a styrene monomer unit content of 45 to 80% by mass and a polyolefin resin B having a weight average molecular weight of 1,000,000 to 7,000,000 in an amount of 5 to 50 parts by mass per 100 parts by mass of the styrene elastomer A, wherein the styrene elastomer A is a styrene copolymer or a hydrogenated product thereof having hard segments which are polymerized units of a styrene monomer and soft segments which are copolymerized units of the styrene monomer with at least one of an olefin and a conjugated diene.

[0005] Patent Document 2 proposes a thermoplastic elastomer composition comprising a propylene polymer as component (A), a block copolymer and / or a hydrogenated product thereof as component (B) having at least two polymer blocks P mainly composed of aromatic vinyl compound units and at least one polymer block Q mainly composed of conjugated diene compound units, and component (C) an aryl group-containing organopolysiloxane. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-83885 [Patent Document 2] International Publication No. 2021 / 153183 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, as product shapes have become larger and more complex, problems have been observed in which cracks occur in products when thermoplastic elastomer molded bodies are laminated on hard resins to form composite materials. Cracks often occur after heating, in particular. Patent Documents 1 and 2 do not take into consideration cracks that occur when thermoplastic elastomer molded bodies are combined with other materials, and there is room for improvement in this regard.

[0008] Therefore, an object of the present invention is to provide a styrene-based thermoplastic elastomer composition that is flexible and can suppress the occurrence of cracks when combined with a hard resin. [Means for solving the problem]

[0009] As a result of extensive research into solving the above-mentioned problems, the present inventors have discovered that when a styrene-based thermoplastic elastomer molded body is laminated to a hard resin, cracks occur in the product due to the difference in shrinkage between the two materials. They have also discovered that a styrene-based thermoplastic elastomer composition containing a polyolefin and a styrene-based rubber, which is injection-molded under conditions of an injection pressure of 50 MPa, a cylinder temperature of 220°C, and a mold temperature of 40°C to obtain a sheet of 2 mm thick x 120 mm wide x 120 mm long on which scribe lines are processed in the composition flow direction so that the distance between the scribe lines is 100 mm in the actual mold dimensions, has a molding shrinkage of less than 10, can suppress the occurrence of cracks when composited with a hard resin, thereby completing the present invention.

[0010] Aspect 1 of the present invention comprises the following components (A) and (B): Component (A): Polyolefin Component (B): Styrene rubber The styrene-based thermoplastic elastomer composition is injection-molded under conditions of an injection pressure of 50 MPa, a cylinder temperature of 220°C, and a mold temperature of 40°C to obtain a sheet having a thickness of 2 mm, a width of 120 mm, and a length of 120 mm, on which scribe lines are processed in the direction of composition flow, with the distance between the scribe lines being 100 mm according to the actual mold dimensions. When the sheet has a molding shrinkage rate of less than 10, as calculated according to the following formula (1): Mold shrinkage rate = (100 - distance between scribed lines (mm)) x 10 (1)

[0011] A second aspect of the present invention is the styrene-based thermoplastic elastomer composition of the first aspect, wherein the component (B) is the following component (B1): Component (B1): A hydrogenated block copolymer having a block containing an aromatic vinyl compound unit and a conjugated diene compound unit, the melt flow rate of which is 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).

[0012] A third aspect of the present invention is the styrene-based thermoplastic elastomer composition according to the second aspect, which is the styrene-based thermoplastic elastomer composition of the first or second aspect, further comprising the following component (B2) as the component (B): Component (B2): A block copolymer and / or a hydrogenated product thereof that does not contain the component (B1) and has at least one block mainly composed of conjugated diene compound units and at least one block mainly composed of aromatic vinyl compound units.

[0013] A fourth aspect of the present invention is the styrene-based thermoplastic elastomer composition of any one of the first to third aspects, wherein the weight average molecular weight of the component (B2) is 100,000 or more and 1,000,000 or less.

[0014] A fifth aspect of the present invention is a styrene-based thermoplastic elastomer composition according to any one of the first to fourth aspects, further comprising the following component (C): Component (C): Hydrocarbon-based rubber softener

[0015] A sixth aspect of the present invention is the styrene-based thermoplastic elastomer composition of the fifth aspect, wherein the content of the component (B1) is 5 to 70 parts by mass per 100 parts by mass of the total of the components (A) to (C).

[0016] A seventh aspect of the present invention is a styrene-based thermoplastic elastomer composition according to the fifth or sixth aspect, wherein, when the total amount of the component (B2) and the component (C) is 100 parts by mass, the mass ratio of the component (B2) / the component (C) is 20 to 80 / 80 to 20.

[0017] Aspect 8 of the present invention is a styrene-based thermoplastic elastomer composition according to any one of Aspects 1 to 7, wherein the hardness measured using a Type A durometer in accordance with JIS K6253 (2006 edition) is 10 or more and 95 or less.

[0018] A ninth aspect of the present invention is a molded article made of the styrene-based thermoplastic elastomer composition of any one of the first to eighth aspects.

[0019] A tenth aspect of the present invention is a molded article comprising a layer made of the styrene-based thermoplastic elastomer composition according to any one of the first to eighth aspects and a layer made of a polyolefin or a polyamide. [Effects of the Invention]

[0020] The styrene-based thermoplastic elastomer composition of the present invention has excellent flexibility and low shrinkage, and therefore can suppress the occurrence of cracks when combined with a hard resin. DETAILED DESCRIPTION OF THE INVENTION

[0021] 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 "~"

[0022] [Thermoplastic elastomer composition] The styrene-based thermoplastic elastomer composition of the present invention (hereinafter sometimes referred to as "the thermoplastic elastomer composition of the present invention") contains a polyolefin as component (A) and a styrene-based rubber as component (B), and is injection-molded under conditions of an injection pressure of 50 MPa, a cylinder temperature of 220°C, and a mold temperature of 40°C to obtain a sheet (hereinafter sometimes referred to as "evaluation sheet") having a thickness of 2 mm, a width of 120 mm, and a length of 120 mm, on which scribe lines are processed in the composition flow direction so that the distance between the scribe lines is 100 mm in the actual mold dimensions. The molding shrinkage of the sheet calculated according to the following formula (1) is less than 10: Mold shrinkage rate = (100 - distance between scribed lines (mm)) x 10 (1)

[0023] 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 mol % or more.

[0024] <Component (A)> Examples of the polyolefin of component (A) include polypropylene, polyethylene, poly-1-butene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, and other ethylene copolymers, with polypropylene being preferred due to its excellent heat resistance, moldability, etc.

[0025] Polypropylene is a polyolefin in which the content of propylene units relative to all monomer units is more than 50% by mass.

[0026] 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.

[0027] 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, such as those obtained by polymerizing polypropylene in the first stage and a propylene-ethylene copolymer in the second stage.

[0028] 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, there is no particular upper limit for the content of propylene units in polypropylene, and it is usually 100% by mass. The content of propylene units in polypropylene can be determined by infrared spectroscopy.

[0029] From the viewpoint of heat resistance, 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, while from the viewpoint of moldability, 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.

[0030] Here, the weight average molecular weight (Mw) of the polyolefin is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (hereinafter sometimes abbreviated as "GPC") under the following conditions. (Measurement conditions) Equipment: Tosoh HLC-8321 GPC / HT Column: TSKgel GMHHR-H(20)HT (3 columns) Carrier: 1,2,4-trichlorobenzene Measurement temperature: 140℃ Flow rate: 1.0mL / min Injection volume: 300μL Concentration: 1mg / mL Detector: Differential refraction Molecular weight standard: Standard polystyrene

[0031] 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 the present invention has excellent moldability, the resulting automobile interior parts have good appearance, and the mechanical properties, particularly the tensile breaking strength, can be controlled within a desired range. 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.

[0032] The melt flow rate of polyolefins is measured in accordance with JIS K7210-1 (2014 edition) under conditions of a measurement temperature of 230°C and a measurement load of 2.16 kgf.

[0033] Examples of methods for producing polyolefins 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 a polymerization monomer as a 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 using hydrogen or other known molecular weight modifiers. The polymerization can be carried out by a continuous or batch reaction under commonly used conditions. Furthermore, the polymerization reaction can be carried out in one stage or multiple stages.

[0034] Examples of the catalyst used include Ziegler catalysts and metallocene catalysts, and among these catalysts, metallocene catalysts are preferred.

[0035] 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 such as titanium trichloride, titanium tetrachloride, or trichloroethoxytitanium, and an organometallic component, such as an alkylaluminum compound or its halide, hydride, or alkoxide, and a three-component catalyst obtained by adding an electron-donating compound containing nitrogen, carbon, phosphorus, sulfur, oxygen, silicon, or the like to any of the above components.

[0036] The metallocene catalyst is not limited to the following, but may be, for example, a catalyst comprising a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton (a so-called metallocene compound), a co-catalyst capable of activating the metallocene compound to a stable ionic state by reacting with the metallocene compound, and, if necessary, an organoaluminum compound, and any known catalyst can be used. The metallocene compound is preferably a bridged metallocene compound capable of stereoregular polymerization of propylene, and more preferably a bridged metallocene compound capable of isoregular polymerization of propylene.

[0037] The polyolefin of component (A) may be a commercially available product. For example, commercially available polypropylene may be procured from the manufacturers listed below and may be selected appropriately. Commercially available polypropylene products include Novatec® PP from Japan Polypropylene Corporation, Prime Polypro® from Prime Polymer Co., Ltd., Sumitomo Noblen® from Sumitomo Chemical Co., Ltd., polypropylene block copolymer from SunAllomer Corporation, Moplen® from LyondellBasell Corporation, ExxonMobil PP from ExxonMobil Corporation, Formolene® from Formosa Plastics, Borealis PP from Borealis, Seetec PP from LG Chemical, ASI POLYPROPYLENE from A. Schulman, INEOS PP from INEOS Olefins & Polymers, Braskem PP from Braskem, Samsung Total from SAMSUNG TOTAL PETROCHEMICALS, Sabic® PP from Sabic, TOTAL PETROCHEMICALS Polypropylene from TOTAL PETROCHEMICALS, and YUPLENE® from SK Corporation.

[0038] The thermoplastic elastomer composition of the present invention may contain only one type of polyolefin such as polypropylene as component (A), or may contain two or more types of polyolefins that differ in the type, content, physical properties, etc. of the monomer units contained therein.

[0039] <Ingredient (B)> The styrene rubber of component (B) refers to a block copolymer of an aromatic vinyl compound and a conjugated diene compound, which has a styrene structure in the main chain. Examples of styrene-based rubbers include styrene-butadiene rubber (SBR), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene copolymer rubber (HSBR), styrene-ethylene-styrene block copolymer (SES), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS), etc. The thermoplastic elastomer composition of the present invention may contain one type of styrene-based rubber as component (B) alone, or two or more types may be used in combination.

[0040] The thermoplastic elastomer composition of the present invention preferably contains, as component (B), a hydrogenated product of a block copolymer having a block containing aromatic vinyl compound units and conjugated diene compound units (hereinafter, sometimes referred to as "block P"), which 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) (hereinafter, sometimes referred to as "component (B1)"). By including component (B1) in the thermoplastic elastomer composition of the present invention, the styrene-based rubber is more likely to be oriented in the composition, and the molding shrinkage of the evaluation sheet formed from the thermoplastic elastomer composition can be adjusted to be smaller.

[0041] 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, styrene, α-methylstyrene, and p-methylstyrene are preferably used from the viewpoints of availability and productivity. Styrene is more preferred. The aromatic vinyl compound units contained in the block P may be only one type of aromatic vinyl compound unit, or may contain two or more types of aromatic vinyl compound units.

[0042] 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, but 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 units contained in the block P may be only one type of conjugated diene compound unit, or may contain two or more types of conjugated diene compound units.

[0043] Block P may contain monomer units other than aromatic vinyl compound units and conjugated diene compound units. 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 aromatic vinyl compound units and conjugated diene compound units.

[0044] 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.

[0045] The content of conjugated diene compound units in 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 conjugated diene compound units in block P is preferably in the range of 21 to 70% by mass.

[0046] The mass ratio of aromatic vinyl compound units to conjugated diene compound units in block P is preferably in the range of 1:0.21 to 1:2.3, more preferably 1:0.25 to 1:1.8.

[0047] The hydrogenated product of the block copolymer having the block P, which is the component (B1), is a block copolymer in which the conjugated diene compound units in the block copolymer have been partially or entirely hydrogenated by subjecting the block copolymer having the block P to a hydrogenation treatment.

[0048] A block copolymer having block P contains the above-described block P and polymer blocks and monomer units other than block P. The block copolymer having block P may be linear, branched, radial, or the like.

[0049] The block P is the polymer block described above, but the block P may contain only one type of block, and when a block copolymer contains multiple blocks P, the compound units thereof may be the same or different.

[0050] Examples of polymer blocks other than block P include polymer blocks mainly composed of aromatic vinyl compound units.

[0051] The monomer unit may be, for example, an aromatic vinyl compound.

[0052] The content of block P in component (B1) is preferably in the range of 60 to 99% by mass. When the content of block P is 60% by mass or more, the molding shrinkage of the thermoplastic elastomer composition can be reduced, making it easier to achieve the effects of the present invention. When the content of block P is 99% by mass or less, it is easier to achieve both mechanical strength and flexibility while suppressing bleed-out. The content of block P in component (B1) 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.

[0053] The hydrogenation rate of component (B1) is preferably 20% or more from the viewpoint 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 it is 100% or less.

[0054] The melt flow rate (MFR, measured at 190°C and under a load of 2.16 kgf) of component (B1) 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 the present invention, allowing for a small mold shrinkage rate. A MFR of 40 g / 10 min or less helps to prevent flash formation during molding of the thermoplastic elastomer composition of the present invention. The melt flow rate of component (B1) is preferably 7 g / 10 min or more, more preferably 10 g / 10 min or more, even more preferably 15 g / 10 min or more, and is preferably 35 g / 10 min or less, more preferably 30 g / 10 min or less, even more preferably 28 g / 10 min or less.

[0055] The melt flow rate (MFR) of component (B1) is measured in accordance with JIS K7210-1 (2014 edition) under conditions of 190°C and a load of 2.16 kgf.

[0056] The component (B1) can be produced by known polymerization methods, such as batch polymerization and continuous polymerization.

[0057] Component (B1) may be a commercially available product. Examples of commercially available component (B1) include "SOE (registered trademark)" manufactured by Asahi Kasei Corporation.

[0058] The thermoplastic elastomer composition of the present invention preferably does not contain component (B1) and contains, as component (B), a block copolymer having at least one block mainly composed of conjugated diene compound units (hereinafter sometimes referred to as "block Q") and at least one block mainly composed of aromatic vinyl compound units (hereinafter sometimes referred to as "block R") and / or a hydrogenated product thereof (hereinafter sometimes referred to as "component (B2)"). Component (B2) has a high affinity with softeners such as oil, and by including component (B2) in the thermoplastic elastomer composition of the present invention, the flexibility of the thermoplastic elastomer composition can be increased. Furthermore, by using component (B1) and component (B2) in combination, the molding shrinkage of the thermoplastic elastomer composition can be easily reduced and the flexibility of the composition can be increased.

[0059] Examples of the conjugated diene compound constituting the block Q include the same conjugated diene compounds as those exemplified for the above component (B1), 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 preferred 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 two or more types of conjugated diene compound units, and may also contain monomer units other than conjugated diene compound units.

[0060] Examples of aromatic vinyl compounds constituting the block R include the same aromatic vinyl compounds as those exemplified for the above component (B1), such as styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. Among these, styrene, α-methylstyrene, and p-methylstyrene are preferred from the viewpoints of availability and productivity. Styrene is more preferred. The block R may be composed of one type of aromatic vinyl compound unit or two or more types of aromatic vinyl compound units, and may also contain monomer units other than vinyl aromatic compound units.

[0061] 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 the formula, Q represents a block Q, R represents a block R, and n represents an integer of 1 to 5.)

[0062] 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.

[0063] From the viewpoint of rubber elasticity of the composition, component (B2) used in the present invention 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.

[0064] Component (B2) used in the present invention 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 block copolymer represented by formula (I) or (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) where n is 1 to 3, particularly preferably a hydrogenated product of a block copolymer represented by formula (II) where n is 1 to 2, and most preferably a hydrogenated product of a block copolymer represented by formula (II) where n is 1.

[0065] The content of block Q in component (B2) is preferably in the range of 30 to 95% by mass. When the content of block Q is 30% by mass or more, the flexibility of the composition can be improved while suppressing bleed-out, and when it is 95% by mass or less, it is easy to achieve both mechanical strength and flexibility. The content of block Q in component (B2) 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.

[0066] The proportion of R blocks in component (B2) is preferably in the range of 5 to 70% by mass. When the content of R blocks 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 flexibility and suppression of bleed-out. The content of the R block in component (B2) 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. When the aromatic vinyl compound constituting the block R in the component (B2) is a styrene unit, the content of the block R can be expressed as the styrene unit content.

[0067] The weight average molecular weight (Mw) of component (B2) is preferably 10,000 or more and 1,000,000 or less. When component (B2) has an Mw of 10,000 or more, the heat resistance and mechanical strength can be improved, and when it is 1,000,000 or less, the flowability of the thermoplastic elastomer composition of the present invention can be improved, resulting in a good molded appearance. The weight average molecular weight (Mw) of component (B2) 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.

[0068] The weight average molecular weight (Mw) of the component (B2) is a weight average molecular weight measured by GPC under the following conditions in terms of polystyrene. (Measurement conditions) Equipment: 150C ALC / GPC manufactured by Nihon Millipore Column: Showa Denko "AD80M / S" x 3 Detector: FOXBORO infrared spectrophotometer "MIRANIA" Wavelength: 3.42μm Solvent: o-dichlorobenzene Measurement temperature: 140℃ Flow rate: 1cm 3 / min Injection volume: 200 microliters Concentration: 2mg / cm 3 0.2% by mass of 2,6-di-t-butyl-p-phenol added as an antioxidant

[0069] The component (B2) can be produced by known polymerization methods, such as batch polymerization and continuous polymerization.

[0070] Component (B2) can be a commercially available product. Examples of available component (B2) include "Kraton (registered trademark) G" manufactured by Kraton Polymers, "Septon (registered trademark)" manufactured by Kuraray Co., Ltd., "Tuftec (registered trademark)" and "SOE (registered trademark)" manufactured by Asahi Kasei Corporation, and "TAIPOL (registered trademark)" manufactured by TSRC.

[0071] <Ingredient (C)> The thermoplastic elastomer composition of the present invention preferably further contains a hydrocarbon-based rubber softener as component (C), which is effective in improving the flexibility and flowability of the thermoplastic elastomer composition of the present invention.

[0072] Examples of hydrocarbon-based rubber softeners include mineral oil-based softeners and synthetic resin-based softeners, with mineral oil-based softeners being more preferred. These softeners have a high affinity for component (B2) when component (B) contains component (B2), and therefore can improve the flexibility of the thermoplastic elastomer composition of the present invention.

[0073] Mineral oil-based softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons. Those in which 50% or more of the carbon atoms are derived from paraffinic hydrocarbons are called paraffinic oils, those in which 30-45% of the carbon atoms are derived from naphthenic hydrocarbons are called naphthenic oils, and those in which 35% or more of the carbon atoms are derived from aromatic hydrocarbons are called aromatic oils. The hydrocarbon-based rubber softener used as component (C) may be any one of the above-mentioned softeners or a mixture of multiple types. Among these, paraffinic oils are preferred because of their good color. Examples of synthetic resin-based softeners include polybutene and low-molecular-weight polybutadiene.

[0074] The kinematic viscosity at 40°C (according to JIS K2283) of the hydrocarbon-based rubber softener is preferably low in terms of improving the fluidity of the thermoplastic elastomer composition of the present invention, but is preferably high in terms of preventing fogging and the like. Specifically, it is preferably 20 centistokes (cSt) or more, more preferably 50 centistokes or more. On the other hand, it is preferably 800 centistokes or less, and more preferably 600 centistokes or less.

[0075] 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.

[0076] The hydrocarbon-based rubber softener of component (C) may be used alone or as a mixture of two or more kinds in any combination and ratio.

[0077] <Mixing ratio> In the thermoplastic elastomer composition of the present invention, the content ratios of components (A), (B), and (C) are preferably 3 to 49 parts by mass of component (A), 5 to 90 parts by mass of component (B), and 0 to 50 parts by mass of component (C), relative to a total of 100 parts by mass of these components. By including the polyolefin of component (A) in the above range in the thermoplastic elastomer composition of the present invention, the effects of improving heat resistance and mechanical properties of component (A) can be fully obtained while the effects of blending other components can be fully obtained. Furthermore, by including the styrene-based rubber of component (B) within the above range, the effects of compounding the other components can be fully obtained, and the effects of improving flexibility, good touch, and scratch resistance due to component (B) can also be fully obtained. Furthermore, when the hydrocarbon-based rubber softener of component (C) is contained, by including it within the above range, the effect of improving flexibility and flowability of component (C) can be fully obtained while the compounding effects of the other components are fully obtained.

[0078] For a total of 100 parts by mass of components (A) to (C), the amount of component (A) is more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less. Furthermore, relative to 100 parts by mass of the total of components (A) to (C), component (B) is more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less. Furthermore, relative to 100 parts by mass of the total of components (A) to (C), component (C) is more preferably 15 parts by mass or more, even more preferably 18 parts by mass or more, and particularly preferably 20 parts by mass or more, and is more preferably 48 parts by mass or less, even more preferably 45 parts by mass or less.

[0079] In the present invention, when component (B1) is contained as component (B), the content of component (B1) is preferably 5 to 70 parts by mass per 100 parts by mass of the total of components (A) to (C). When the thermoplastic elastomer composition of the present invention contains the component (B1) in the above range, the molding shrinkage of the thermoplastic elastomer composition is easily reduced. For a total of 100 parts by mass of components (A) to (C), the amount of component (B1) is more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and more preferably 65 parts by mass or less, even more preferably 55 parts by mass or less.

[0080] Furthermore, in the present invention, when component (C) is contained and component (B2) is contained as component (B), the mass ratio of component (B2) / component (C) is preferably 20 to 80 / 80 to 20, where the total of components (B2) and (C) is 100 parts by mass. When the content ratio of component (B2) to component (C) is within the above range, the flexibility of the thermoplastic elastomer composition of the present invention is increased, and therefore the moldability is improved. The content ratio of component (B2) to component (C) is more preferably 22-78 / 78-22, and even more preferably 25-75 / 75-25.

[0081] <Other ingredients> The thermoplastic elastomer composition of the present invention may contain other components (sometimes simply referred to herein as "other components") in addition to the above-described components (A) to (C) as necessary, provided that the object of the present invention is not impaired. Examples of other components include resins and elastomers other than components (A) and (B) (sometimes collectively referred to herein as "other resins"), and various additives.

[0082] Other resins that may be contained in the thermoplastic elastomer composition of the present invention include polyolefin resins (excluding those corresponding to component (A) above), polyester resins, polyamide resins, styrene resins (excluding those corresponding to component (B) above), acrylic resins, polycarbonate resins, polyphenylene ethers, polyvinyl chloride resins, and other resins; olefin elastomers such as ethylene-propylene copolymer rubber (EPM), ethylene-propylene-non-conjugated diene copolymer rubber (EPDM), ethylene-butene copolymer rubber (EBM), and ethylene-propylene-butene copolymer rubber; polyamide elastomers such as polyamide-polyol copolymers; polyvinyl chloride elastomers and polybutadiene elastomers; their hydrogenated products; products modified with acid anhydrides or the like to introduce polar functional groups; and products obtained by grafting, randomly, and / or block copolymerizing other monomers. The above-listed other resins may be used alone or in combination of two or more.

[0083] Furthermore, examples of additives that may be contained in the thermoplastic elastomer composition of the present invention 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.

[0084] 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.

[0085] 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 Each independently represents alkyl. In the formula, preferred R 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.

[0086] As the dithiocarbamate-based 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] These antioxidants may be used alone or in combination of two or more.

[0091] When the thermoplastic elastomer composition of the present invention 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 (C). 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 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 (C).

[0092] Examples of the lubricant include fatty acid amides, fatty acid metal salts, and organopolysiloxanes.

[0093] When the thermoplastic elastomer composition of the present invention contains a lubricant, the content of the lubricant is preferably 0.01 to 10 parts by mass per 100 parts by mass of the total of components (A) to (C). A content of 0.01 part by mass or more can improve mold releasability and abrasion resistance, while a content of 10 parts by mass or less can suppress the stickiness characteristic of lubricants. The content of the 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 (C).

[0094] Fillers are broadly classified into organic fillers and inorganic fillers. Examples of organic fillers include naturally occurring polymers such as starch, cellulose fine particles, wood flour, soybean pulp, rice husks, and bran, as well as modified versions of these. Examples of inorganic fillers include talc, calcium carbonate, kaolin clay, calcium oxide, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloons, carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fibers, metal whiskers, ceramic whiskers, potassium titanate, boron nitride, graphite, carbon fibers, glass fibers, mica, metal soap, and titanium dioxide.

[0095] It is preferable to use a filler having an aspect ratio of 5 or more, since this makes it easier to adjust the molding shrinkage rate of the thermoplastic elastomer composition.

[0096] When the thermoplastic elastomer composition of the present invention contains a filler, the content of the filler is preferably in the range of 1 to 40 parts by mass per 100 parts by mass of the total of components (A) to (C).

[0097] <Method of producing thermoplastic elastomer composition> The method for producing the thermoplastic elastomer composition of the present invention is not particularly limited, and the composition can be produced, for example, by dry-blending components (A) to (C) and other components used as needed, followed by melt-kneading in accordance with a conventional method.

[0098] 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.

[0099] [Physical properties of thermoplastic elastomer composition] <Molding shrinkage rate> The thermoplastic elastomer composition of the present invention is injection molded under conditions of an injection pressure of 50 MPa, a cylinder temperature of 220°C, and a mold temperature of 40°C to obtain a sheet (evaluation sheet) having a thickness of 2 mm, a width of 120 mm, and a length of 120 mm, on which scribe lines are processed in the composition flow direction so that the distance between the scribe lines is 100 mm in the actual mold dimensions.The mold shrinkage of the sheet calculated according to the following formula (1) is less than 10: Mold shrinkage rate = (100 - distance between scribed lines (mm)) x 10 (1)

[0100] Through investigations by the present inventors, it has been found that in order to suppress the occurrence of cracks when a thermoplastic elastomer molded article is composited with a hard resin, it is sufficient to use a styrene-based thermoplastic elastomer composition containing polyolefin and styrene-based rubber, and to use a thermoplastic elastomer composition such that the molding shrinkage of an evaluation sheet formed from the composition is less than 10. The molding shrinkage can be adjusted, for example, by using a component (B) that has high fluidity or by having blocks with a specific structure, thereby strengthening the orientation of the rubber in the styrene-based thermoplastic elastomer composition.

[0101] When the molding shrinkage rate of the evaluation sheet is less than 10, the shrinkage is low, and when the thermoplastic elastomer composition of the present invention is used and laminated on a hard resin or the like to form a composite, the occurrence of cracks can be suppressed. The molding shrinkage of the evaluation sheet is preferably 9 or less, and the lower limit is not particularly limited since the smaller the molding shrinkage, the better.

[0102] <Duro hardness A> The thermoplastic elastomer composition of the present invention preferably has a hardness (duronium hardness A) measured using a type A durometer in accordance with JIS K6253 (2006 edition) of 10 or more and 95 or less. When the duronium hardness A is 10 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 durometer hardness A of the thermoplastic elastomer composition is more preferably 20 or more, even more preferably 30 or more, and more preferably 92 or less, even more preferably 90 or less.

[0103] <Melt flow rate> Furthermore, the thermoplastic elastomer composition of the present invention preferably has a melt flow rate (MFR, measurement temperature 230°C, measurement load 2.16 kgf) of 1 g / 10 min or more. A melt flow rate (MFR) of 1 g / 10 min or more suppresses insufficient filling into a mold and facilitates thin-wall molding. The melt flow rate (MFR) of the thermoplastic elastomer composition is more preferably 5 g / 10 min or more, and even more preferably 10 g / 10 min or more. From the viewpoint of fluidity, a higher melt flow rate (MFR) is preferable, and there is no particular upper limit, but a melt flow rate (MFR) of 200 g / 10 min or less is preferable because, in addition to fluidity, it is easy to suppress the occurrence of flash during molding.

[0104] [Molded body] The molded article of the present invention is produced by molding the thermoplastic elastomer composition of the present invention. The thermoplastic elastomer composition of the present invention can be molded using various molding methods such as conventional injection molding and extrusion molding.

[0105] The molding conditions for injection molding the thermoplastic elastomer composition of the present invention are as follows. The molding temperature is preferably 160 to 250°C, more preferably 170 to 220°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.

[0106] The molded article of the present invention can be a composite molded article having a layer made of the thermoplastic elastomer composition of the present invention and a layer made of a polyolefin or polyamide. A composite molded article obtained by injection-molding the thermoplastic elastomer composition of the present invention and heat-fusing it to a polyolefin- or polyamide-based hard resin can be suitably used, for example, as an automobile interior component. [Example]

[0107] 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.

[0108] 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.

[0109] [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: SunAllomer "PWH00N" (propylene homopolymer, MFR (JIS K7210-1, 230°C, 2.16 kgf load): 1800 g / 10 min)

[0110] <Ingredient (B)> B-1: "SOE-SS (registered trademark) L614" 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) (corresponding to component (B1)) B-2: Kraton® G1633EU manufactured by Kraton Polymers (hydrogenated styrene-butadiene-styrene block copolymer, weight average molecular weight: 443,000, styrene unit content: 30% by mass) (corresponding to component (B2)) B-3: "SOE-SS (registered trademark) S1605" manufactured by Asahi Kasei Corporation (hydrogenated copolymer of styrene and butadiene having blocks containing styrene units and butadiene units, MFR (JIS K7210-1, 190°C, 2.16 kgf load): 0.8 g / 10 min)

[0111] <Ingredient (C)> C-1: Idemitsu Kosan's "Diana Process Oil PW90" (paraffinic oil, kinematic viscosity (40°C): 90 cSt)

[0112] <Other additives> D-1: "MB50-001" manufactured by Toray Dow Corning Co., Ltd. (dimethylpolysiloxane masterbatch, dimethylpolysiloxane content: 50% by mass, viscosity (JIS Z8803, 25°C): 1,000,000 cSt or more)

[0113] [Evaluation method] The thermoplastic elastomer compositions in the following examples and comparative examples were evaluated as follows. In the measurements of (1) and (3) below, each thermoplastic elastomer composition was injection molded using an inline 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 (2) 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.

[0114] (1) Hardness using a Type A durometer (Duro hardness A) In accordance with JIS K6253 (Duro-A) (2006 edition), the hardness was measured after 15 seconds using a type A durometer.

[0115] (2) Molding appearance (flow marks) The degree of flow marks was visually evaluated according to the following criteria. The fewer flow marks there were in the injection-molded product (sheet), the better the molded appearance was judged to be. A rating of 2 points means that the product can be used for practical purposes. <Evaluation criteria> 0 points: Flow marks are visible on the entire surface of the molded product. 1 point: Flow marks are visible in some parts of the molded product. 2 points: No flow marks are visible.

[0116] (3) Mold shrinkage rate The distance (unit: mm) between the marking lines of the obtained injection sheet was measured, and the molding shrinkage was calculated according to the following formula (1). Mold shrinkage rate = (100 - distance between scribed lines (mm)) x 10 (1)

[0117] [Example 1] A total of 100 parts by mass of 15 parts by mass of component (A-1), 9 parts by mass of component (A-2), 35 parts by mass of component (B-1), 10.3 parts by mass of component (B-2), and 30.7 parts by mass of component (C-1) were mixed with 1.5 parts by mass of component (D-1) (the amount of dimethylpolysiloxane in component (D-1) (actual amount 50%)) and 0.1 parts by mass of an antioxidant ("Songnox (registered trademark) 1076" manufactured by Songwon Co., Ltd.), and 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 thermoplastic elastomer composition thus obtained was subjected to the evaluations (1) to (3) above. The evaluation results are shown in Table 1.

[0118] [Comparative Example 1] Pellets of a thermoplastic elastomer composition were obtained in the same manner as in Example 1, except that the raw material blending amounts shown in Table 1 were used. The obtained thermoplastic elastomer composition was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0119] [Table 1]

[0120] As can be seen from Table 1, the molding shrinkage of Example 1 when injection-molded is less than 10, and when it is combined with another hard resin, the difference in molding shrinkage between the two is small, so that the occurrence of cracks in the product can be suppressed. Example 1 was also found to be excellent in molded appearance, flowability, and flexibility. [Industrial Applicability]

[0121] Various members obtained from the styrene-based thermoplastic elastomer composition of the present invention are excellent in touch, scratch resistance, light resistance, and heat resistance, and when used in automobile interior members, they are used to enhance the luxury and comfort of automobile interior spaces, and further, are suitably used to eliminate the need for painting from the viewpoints of reducing environmental load and process steps.

Claims

1. Contains the following components (A) and (B): Component (A): Polyolefin Component (B): Styrene-based rubber A styrene-based thermoplastic elastomer composition, wherein a sheet having a thickness of 2 mm, a width of 120 mm, and a length of 120 mm is obtained by injection molding a styrene-based thermoplastic elastomer composition under conditions of an injection pressure of 50 MPa, a cylinder temperature of 220°C, and a mold temperature of 40°C, and on which scribe lines are processed in the composition flow direction so that the distance between the scribe lines is 100 mm in the actual mold dimensions, the molding shrinkage of the sheet calculated according to the following formula (1) is less than 10: Mold shrinkage rate = (100 - distance between marking lines (mm)) × 10 (1)

2. The styrenic thermoplastic elastomer composition according to claim 1, wherein the component (B) is the following component (B1): Component (B1): A hydrogenated block copolymer having a block containing an aromatic vinyl compound unit and a conjugated diene compound unit, the melt flow rate of which is 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).

3. The styrenic thermoplastic elastomer composition according to claim 2, further comprising the following component (B2) as the component (B): Component (B2): A block copolymer and / or a hydrogenated product thereof that does not contain the component (B1) and has at least one block mainly composed of conjugated diene compound units and at least one block mainly composed of aromatic vinyl compound units.

4. The styrene-based thermoplastic elastomer composition according to claim 3, wherein the weight average molecular weight of the component (B2) is 100,000 or more and 1,000,000 or less.

5. The styrenic thermoplastic elastomer composition according to claim 1, further comprising the following component (C): Component (C): Hydrocarbon-based rubber softener

6. The styrenic thermoplastic elastomer composition according to claim 5, wherein the component (B) contains the following component (B1), and the content of the component (B1) is 5 to 70 parts by mass per 100 parts by mass of the total of the components (A) to (C): Component (B1): A hydrogenated block copolymer having a block containing an aromatic vinyl compound unit and a conjugated diene compound unit, the melt flow rate of which is 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).

7. 6. The styrenic thermoplastic elastomer composition according to claim 5, wherein the component (B) contains the following components (B1) and (B2), and when the total of the components (B2) and (C) is taken as 100 parts by mass, the mass ratio of component (B2) / component (C) is 20 to 80 / 80 to 20: Component (B1): A hydrogenated block copolymer having a block containing an aromatic vinyl compound unit and a conjugated diene compound unit, the melt flow rate of which is 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). Component (B2): A block copolymer and / or a hydrogenated product thereof that does not contain the component (B1) and has at least one block mainly composed of conjugated diene compound units and at least one block mainly composed of aromatic vinyl compound units.

8. 2. The styrene-based thermoplastic elastomer composition according to claim 1, having a hardness of 10 or more and 95 or less as measured using a type A durometer in accordance with JIS K6253 (2006 edition).

9. A molded article made of the styrene-based thermoplastic elastomer composition according to any one of claims 1 to 8.

10. A molded article comprising a layer made of the styrene-based thermoplastic elastomer composition according to any one of claims 1 to 8 and a layer made of a polyolefin or a polyamide.

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