Thermoplastic elastomer composition and use thereof

Abstract

An object of the present application is to provide a thermoplastic elastomer composition which is low in hardness and soft, and excellent in scratch resistance. The present application relates to a thermoplastic elastomer composition characterized by containing (A) to (D) below. (A) propylene polymer: 100 parts by mass, (B) ethylene-α-olefin copolymer containing ethylene and α-olefin units having 3 to 20 carbon atoms: in the range of 50 to 300 parts by mass, (C) softening agent: in the range of 50 to 280 parts by mass, and (D) hydrogenated product of block copolymer having at least one block having conjugated diene monomer units as a main component and at least one block having vinyl aromatic monomer units as a main component, respectively: in the range of 90 to 400 parts by mass.

Description

Technical Field

[0001] This invention relates to thermoplastic elastomer compositions and their uses. Background Technology

[0002] For interior trim materials such as dashboards and door panels in automobiles, olefin-based thermoplastic elastomers are sometimes used to reduce material weight. When shaping interior trim materials formed from olefin-based thermoplastic elastomers into the shapes of dashboards and door panels, vacuum forming and injection molding are typically employed.

[0003] As olefin-based thermoplastic elastomers for injection molding, for example, International Publication No. 2010 / 067564 (Patent Document 1) discloses a composition containing a polypropylene resin, an olefin copolymer rubber, a hydrogenated block copolymer having vinyl aromatic monomer units, and a softener in a predetermined ratio, and International Publication No. 2011 / 155571 (Patent Document 2) discloses a thermoplastic elastomer composition containing a polypropylene resin, a softener, and a polyorganosiloxane in a predetermined ratio.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2010 / 067564

[0007] Patent Document 2: International Publication No. 2011 / 155571 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] In recent years, there has been a demand for materials that maintain excellent scratch resistance while being softer and less hard than conventional thermoplastic elastomer compositions, from the perspective of improving tactile feel. However, the thermoplastic elastomer compositions described in Patent Documents 1 and 2 were designed to have excellent scratch resistance at conventionally permissible hardness levels, but the scratch resistance required in the low hardness range in recent years is insufficient, and further improvements are desired.

[0010] The object of the present invention is to provide a thermoplastic elastomer composition that is low in hardness, soft, and has excellent scratch resistance.

[0011] Methods for solving problems

[0012] The present invention relates to a thermoplastic elastomer composition, characterized in that it comprises the following (A) to (D).

[0013] (A) Propylene polymer: 100 parts by weight

[0014] (B) Ethylene-α-olefin copolymers comprising ethylene and α-olefin units having 3 to 20 carbon atoms: 50 to 300 parts by mass.

[0015] (C) Softener: 50–280 parts by weight

[0016] (D) Hydrogenates of block copolymers having at least one block with a conjugated diene monomer unit as the main body and at least one block with a vinyl aromatic monomer unit as the main body: in the range of 90 to 400 parts by mass.

[0017] The effects of the invention

[0018] The thermoplastic elastomer composition of the present invention is low in hardness and soft, and has excellent scratch resistance. As a molded body, it is suitable for various known applications such as automotive parts, civil / building materials, electrical / electronic components, hygiene products, films / sheets, foams, and artificial leather. In particular, it is suitable for automotive parts such as interior automotive parts and surface materials such as artificial leather. Detailed Implementation

[0019] In this specification, the numerical range indicated by “~” refers to the range of values ​​recorded before and after “~” as the lower and upper limits.

[0020] <Propylene Polymer (A)>

[0021] The propylene-based polymer (A) (hereinafter sometimes referred to as "component (A)"), which is one of the components of the thermoplastic elastomer composition of the present invention, refers to a polymer in which the content of propylene-derived structural units constituting the polymer is 50 mol% or more, and the content of propylene-derived structural units in component (A) is preferably 90 mol% or more.

[0022] The component (A) involved in this invention may be one or more.

[0023] The component (A) involved in this invention can be a propylene homopolymer or a copolymer of propylene and comonomers other than propylene.

[0024] The structure of component (A) involved in this invention is not particularly limited. For example, the structural unit portion derived from propylene can be isotactic, syndiotactic, or atactic, preferably isotactic. Furthermore, in the case of the above copolymer, it can be any of atactic (also known as atactic PP), block (also known as bPP), or grafted.

[0025] As the aforementioned comonomer, any other monomer capable of copolymerizing with propylene is acceptable, preferably an α-olefin with 2 or 4 to 10 carbon atoms. Specifically, examples include ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene, among which ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene are preferred. One or more comonomers may be used.

[0026] Considering factors such as flexibility, the content of structural units derived from comonomers in the above copolymers is preferably less than 10 mol%.

[0027] The component (A) involved in this invention can be synthesized using conventionally known methods, or commercially available products can be used. Examples of commercially available products include polypropylene from SunAllomer Co., Ltd., Prime Polypro from Prime Polymer Co., Ltd., NOVATEC from Nippon Polypropylene Co., Ltd., and SCG PP from SCG Plastics Co., Ltd.

[0028] The component (A) involved in this invention can be a crystalline polymer, or it can be a non-crystalline polymer. Here, crystallinity refers to the melting point (Tm) observed in differential scanning calorimetry (DSC).

[0029] When the component (A) of the present invention is a crystalline polymer, its melting point (measured according to the method of JIS K 7121) is preferably 100°C or higher, more preferably 120°C or higher, more preferably 180°C or lower, and more preferably 170°C or lower, from the perspective of heat resistance and other aspects.

[0030] The MFR (measured according to ASTM D 1238-65T, 230°C, 2.16 kg load) of component (A) involved in this invention is preferably 0.1 to 100 g / 10 min, more preferably 0.1 to 50 g / 10 min.

[0031] If the MFR of component (A) involved in this invention is within the above range, a composition with excellent heat resistance, mechanical strength, flowability and molding processability can be easily obtained.

[0032] <Ethylene-α-olefin copolymer (B)>

[0033] The ethylene-α-olefin copolymer (B), which is one of the components of the thermoplastic elastomer composition of the present invention, is an ethylene-α-olefin copolymer comprising units derived from ethylene and units derived from α-olefins having 3 to 20 carbon atoms.

[0034] The ethylene-α-olefin copolymer (B) (hereinafter sometimes referred to as "component (B)") of the present invention 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 flexibility, α-olefins having 3 to 12 carbon atoms are preferred, propylene, 1-butene, and 1-octene are more preferred, and 1-octene is even more preferred.

[0035] In component (B) of the present invention, the ethylene-derived units are typically in the range of 70 to 99 mol%, preferably in the range of 80 to 97 mol%, and the α-olefin-derived units having 3 to 20 carbon atoms are in the range of 1 to 30 mol%, preferably in the range of 3 to 20 mol% [wherein the total amount of the ethylene-derived units and the α-olefin-derived units having 3 to 20 carbon atoms is set to 100 mol%]. Maintaining the content of the ethylene-derived units within the above ranges is preferred for obtaining a thermoplastic elastomer composition with excellent mechanical strength.

[0036] The component (B) of this invention enables copolymerization of monomers having unsaturated bonds as needed. Preferred monomers having unsaturated bonds include, for example, conjugated dienes such as butadiene and isoprene; non-conjugated dienes such as 1,4-hexadiene; cyclic diene compounds such as dicyclopentadiene and norbornene derivatives; and acetylene compounds. Among these, from the viewpoint of flexibility, ethylidene norbornene (ENB) and dicyclopentadiene (DCP) are more preferred.

[0037] The MFR (ASTM D1238 load 2.16 kg, temperature 190 °C) of component (B) involved in this invention is generally in the range of 0.1 to 20 g / 10 min, preferably in the range of 0.3 to 10 g / 10 min.

[0038] By becoming an MFR within the aforementioned range, it is possible to produce thermoplastic elastomer compositions with a superior balance between flowability and mechanical strength.

[0039] The density of component (B) involved in this invention is typically between 0.8 and 0.9 g / cm³. 3 Within the range.

[0040] The component (B) involved in this invention can be manufactured, for example, using known polymerization catalysts such as Ziegler-Natta catalysts, vanadium-based catalysts, and metallocene catalysts. As for the polymerization method, there is no particular limitation; liquid-phase polymerization methods such as solution polymerization, suspension polymerization, and bulk polymerization, gas-phase polymerization, and other known polymerization methods can be used. Furthermore, these copolymers are not limited as long as they achieve the effects of this invention, and can be obtained in the form of commercially available products. Examples of commercially available products include, for example, ENGAGE 8842 (ethylene-1-octene copolymer) manufactured by Dow Corning, Vistalon (registered trademark) manufactured by ExxonMobil, Esprene (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., Mitsui EPT (registered trademark), Tafmer P (registered trademark), and Tafmer A (registered trademark) manufactured by Mitsui Chemicals Co., Ltd.

[0041] <Softener (C)>

[0042] The softener (C) [hereinafter, sometimes referred to as "component (C)"], which is one of the components of the thermoplastic elastomer composition of the present invention, is not particularly limited, and plasticizers commonly used in rubber can be used. From the viewpoint of compatibility with the above-mentioned propylene polymer (A) and ethylene-α-olefin copolymer (B), process oils formed from paraffinic, cycloalkanes, aromatic, and other hydrocarbons are preferred. Among these components (C), from the viewpoint of weather resistance and colorability, process oils with paraffinic hydrocarbons as the main component are preferred, and from the viewpoint of compatibility, process oils with cycloalkanes as the main component are preferred. From the viewpoint of thermal and light stability, the content of aromatic hydrocarbons in the process oil, based on the carbon number ratio specified in ASTM D2140-97, is preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less.

[0043] <Hydrides (D) of Block Copolymers>

[0044] The block copolymer hydride (D) [hereinafter sometimes referred to as "component (D)" or "hydride (D)"] that is one of the components of the thermoplastic elastomer composition of the present invention is a hydride of a block copolymer having at least one block with a conjugated diene monomer unit as the main body and at least one block with a vinyl aromatic monomer unit as the main body.

[0045] The component (D) involved in this invention is derived from at least a portion of the monomer units of a conjugated diene monomer by hydrogenation (hereinafter, sometimes referred to as "hydrogenation").

[0046] Here, "vinyl aromatic monomer unit" refers to the structural unit of a polymer resulting from the polymerization of vinyl aromatic compounds as monomers, whose structure originates from the molecular structure where the two carbons of the substituted vinyl group form the bonding site. Similarly, "conjugated diene monomer unit" refers to the structural unit of a polymer resulting from the polymerization of conjugated dienes as monomers, whose structure originates from the molecular structure where the two carbons of the olefin in the conjugated diene monomer form the bonding site.

[0047] In the component (D) of this invention, "as the main body" means that in a copolymer block, the copolymer block contains 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more of a monomer unit derived from a conjugated diene monomer (or a vinyl aromatic monomer). For example, a block in which a conjugated diene monomer unit is the main body means that the block contains 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more of a monomer unit derived from a conjugated diene monomer.

[0048] The vinyl aromatic monomers in component (D) of this invention are not particularly limited, and examples include, for instance, styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, and other vinyl aromatic compounds. They can be used alone or in combination of two or more. From an economic point of view, styrene is preferred among these.

[0049] The conjugated diene monomer in component (D) of this invention is a diene having one pair of conjugated double bonds, such as 1,3-butadiene (butadiene), 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, etc. From an economic point of view, butadiene and isoprene are preferred. They can be used alone or in combination of two or more.

[0050] The configuration of each block in component (D) of the present invention is not particularly limited, and suitable configurations can be appropriately adopted. For example, when S represents a polymer block formed from a vinyl aromatic monomer unit and B represents a polymer block formed from a unit in which at least a portion of the conjugated diene monomer unit has been hydrogenated, examples of hydrogenated block copolymers include SB and S(BS). n1 (Here, n1 represents an integer from 1 to 3.) S(BSB) n2 (Here, n2 represents an integer from 1 to 2.) Linear block copolymers, (SB) etc., are shown. n3X (where n3 represents an integer from 3 to 6. X represents coupling agent residues such as silicon tetrachloride, tin tetrachloride, and polyepoxide compounds.) are copolymers. Among these, linear block copolymers of SB type 2 (diblock), SBS type 3 (triblock), and SBSB type 4 (tetrablock) are preferred.

[0051] Here, polymer block B can be a polymer block formed solely of conjugated diene monomer units, or it can be a polymer block containing conjugated diene monomer units as the main body and vinyl aromatic monomer units (obtained by copolymerization of conjugated diene monomer units and vinyl aromatic monomer units). In either polymer block, at least a portion of the conjugated diene monomer units are hydrogenated.

[0052] The content of vinyl aromatic monomer units in component (D) of the present invention is 30 to 80% by mass, preferably 40 to 80% by mass, and more preferably 50 to 70% by mass, from the viewpoint of heat resistance and dispersibility. By making the content of vinyl aromatic monomer units 30% by mass or more, the mechanical properties are further improved, and by making the content of vinyl aromatic monomer units 80% by mass or less, the low-temperature properties can be further improved.

[0053] The content of vinyl aromatic monomer units in component (D) of the present invention can be determined by nuclear magnetic resonance spectroscopy (NMR).

[0054] From the viewpoint of mechanical strength, the content of vinyl aromatic monomer unit blocks in component (D) of the present invention is preferably 10% by mass or more, more preferably 10 to 40% by mass. Here, the content of vinyl aromatic compound polymer blocks in component (D) is defined by the mass of vinyl aromatic compound polymer blocks obtained by the following method (excluding vinyl aromatic compound polymers with an average degree of polymerization of about 30 or less), which is defined by the following formula, wherein the method is a method of oxidative decomposition of the unhydrogenated copolymer by using osmium tetroxide as a catalyst with tert-butyl hydrogen peroxide (the method described in I.M. Kolthoff, et al., J. Polym. Sci. 1, 429 (1946), hereinafter also referred to as "osmium tetroxide decomposition method").

[0055] Content of vinyl aromatic polymer blocks (mass %) = (Mass of vinyl aromatic polymer blocks in the copolymer before hydrogenation / Mass of the copolymer before hydrogenation) × 100

[0056] When multiple polymer blocks are present in component (D) of the present invention, their molecular weights, compositions, and other structures may be the same or different. For example, component (D) may contain hydrogenated copolymer blocks comprising conjugated diene monomer units and vinyl aromatic monomer units, as well as hydrogenated copolymer blocks with conjugated diene monomer units as the main component. The boundaries and ends of each block do not need to be clearly defined. The distribution of vinyl aromatic monomer units in each polymer block is not particularly limited; they may be uniformly distributed, or distributed in a conical, stepped, convex, or concave shape. Furthermore, crystalline portions may also be present in the polymer blocks.

[0057] The distribution of vinyl units in the conjugated diene monomer units of each polymer block in component (D) of the present invention is not particularly limited; for example, the distribution may be uneven. Methods for controlling the distribution of vinyl units include adding a vinylizing agent during polymerization and varying the polymerization temperature. Furthermore, the distribution of hydrogenation rates of the conjugated diene monomer units may also be uneven. The distribution of hydrogenation rates can be controlled by changing the distribution of vinyl units; by copolymerizing isoprene and butadiene and then hydrogenating using a hydrogenation catalyst described later; or by utilizing the difference in hydrogenation rates between isoprene and butadiene units.

[0058] In the component (D) of the present invention, from the viewpoint of heat resistance, aging resistance and weather resistance, the unsaturated bonds contained in the conjugated diene monomer unit before hydrogenation are preferably 75 mol% or more, more preferably 85 mol% or more, and even more preferably 97 mol% or more hydrogenated.

[0059] There are no particular limitations on the hydrogenation catalyst used; the following conventionally known catalysts can be used:

[0060] (1) Supported heterogeneous hydrogenation catalysts obtained by supporting metals such as Ni, Pt, Pd, and Ru on carbon, silicon dioxide, alumina, diatomaceous earth, etc.

[0061] (2) So-called Ziegler-type hydrogenation catalysts that use organic acid salts of Ni, Co, Fe, Cr, etc., or transition metal salts such as acetylacetone salts and reducing agents such as organoaluminum.

[0062] (3) Organometallic compounds such as Ti, Ru, Rh, Zr and so on, are homogeneous hydrogenation catalysts.

[0063] As specific hydrogenation catalysts, those described in Japanese Patent Publication Nos. 42-008704, 43-006636, 63-004841, 01-037970, 01-053851, and 02-009041 can be used. Among these, reducing organometallic compounds such as titanium cadmium compounds are preferred hydrogenation catalysts.

[0064] As a titanium decene compound, compounds such as those described in Japanese Patent Application Publication No. 08-109219 can be used. Specific examples include compounds having at least one ligand having a (substituted) cyclopentadienyl skeleton, an indene skeleton, or a fluorene skeleton, such as dicyclopentadienyl titanium dichloride and monopentamethylcyclopentadienyl titanium trichloride.

[0065] Examples of reducing organometallic compounds include organolithium compounds, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.

[0066] The polymerization method for the pre-hydrogenated block copolymer in component (D) of the present invention is not particularly limited, and known methods can also be used. Examples of methods described in Japanese Patent Publication Nos. 36-019286, 43-017979, 46-032415, 49-036957, 48-002423, 48-004106, 56-028925, 59-166518, and 60-186577 are cited.

[0067] As needed, component (D) may have polar groups. Examples of polar groups include, for instance, hydroxyl, carboxyl, carbonyl, thiocarbonyl, acyl halide, acid anhydride, thiocarboxylic acid, aldehyde, thioaldehyde, carboxylic acid ester, amide, sulfonic acid, sulfonate, phosphoric acid, phosphate ester, amino, imino, nitrile, pyridinyl, quinolinyl, epoxy, thioepoxy, thioether, isocyanate, isothiocyanate, silicon halide, alkoxysilyl, tin halide, borate, boron-containing groups, borate, alkoxytin, phenyltin, etc.

[0068] From the viewpoint of softness and scratch resistance, the vinyl bond content in the conjugated diene monomer unit of the pre-hydrogenated block copolymer in component (D) of the present invention is preferably 5 mol% or more, and from the viewpoint of productivity, elongation at break, and scratch resistance, it is preferably 70 mol% or less. The vinyl bond content in the conjugated diene monomer unit is more preferably 10 to 50 mol%, more preferably 10 to 30 mol%, and even more preferably 10 to 25 mol%.

[0069] The vinyl bond content referred to here is the proportion of the unhydrogenated conjugated diene incorporated in the mixture via 1,2-, 3,4-, and 1,4-bond arrangements, and via 1,2- and 3,4-bond arrangements. The vinyl bond content can be determined by NMR.

[0070] The weight-average molecular weight of the component (D) prior to crosslinking is not particularly limited, but from the viewpoint of scratch resistance, it is preferably 50,000 or higher, and from the viewpoint of molding flowability, it is preferably 400,000 or lower, more preferably 50,000 to 300,000. The molecular weight distribution (Mw / Mn: weight-average molecular weight / number-average molecular weight) is not particularly limited, but from the viewpoint of scratch resistance, it is preferably a value close to 1. The weight-average molecular weight and number-average molecular weight can be determined using tetrahydrofuran (1.0 mL / min) as a solvent at an oven temperature of 40°C using gel permeation chromatography (GPC; manufactured by Shimadzu Corporation, instrument name "LC-10"), column: TSKgelGMHXL (4.6 mm ID × 30 cm, 2 columns). The weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) are calculated as the equivalent molecular weight of polystyrene.

[0071] From the viewpoint of abrasion resistance, the block of component (D) of the present invention, which is mainly composed of the above-mentioned conjugated diene monomer unit, preferably includes a copolymer block that is mainly composed of a conjugated diene monomer unit and contains a vinyl aromatic monomer unit.

[0072] The component (D) involved in this invention is not particularly limited, and the aforementioned conjugated diene monomers and vinyl aromatic monomers can be used. Among these, from the viewpoint of balancing mechanical strength and impact resistance, preferred combinations include blocks containing butadiene units and styrene units, blocks containing isoprene units and styrene units, etc.

[0073] The component (D) involved in this invention need only be a component that contains at least a conjugated diene monomer unit as the main component, and the content of each monomer is not particularly limited. In particular, from the viewpoint of balancing mechanical strength and impact resistance, the content of vinyl aromatic monomer units in the copolymer block is preferably 10% by mass or more and less than 50% by mass, more preferably 20% by mass or more and less than 50% by mass.

[0074] <Polyorganosiloxane (E)>

[0075] The structure of the polyorganosiloxane (E) [hereinafter sometimes referred to as "component (E)"], which may be included as one of the components in the thermoplastic elastomer composition of the present invention, is not particularly limited, but from the viewpoint of abrasion resistance and feel, a linear, branched, or cross-linked polymer structure is preferred.

[0076] The component (E) involved in this invention is not particularly limited, and known components can also be used. Preferred polyorganosiloxanes are polymers containing siloxane units having substituents such as alkyl, vinyl, and aryl groups. Among these, polyorganosiloxanes having alkyl groups are particularly preferred, and polyorganosiloxanes having methyl groups are more preferred.

[0077] Specific examples of polyorganosiloxanes containing methyl groups include, for example, polydimethylsiloxane, polymethylphenylsiloxane, and polymethylhydrosiloxane. Among these, polydimethylsiloxane is preferred.

[0078] The kinematic viscosity of component (E) involved in this invention is not particularly limited, but from the viewpoint of abrasion resistance and scratch resistance, the kinematic viscosity (25°C) specified in JIS Z8803 is preferably 5000 centistokes (cSt) or higher. Furthermore, from the viewpoint of improving the dispersibility of component (E) in the resulting thermoplastic elastomer composition, resulting in excellent appearance and further improved quality stability during melt extrusion, the kinematic viscosity of component (E) is preferably less than 3 million cSt. More preferably, the kinematic viscosity of component (E) is 10,000 cSt or higher and less than 3 million cSt, and even more preferably 50,000 cSt or higher and less than 3 million cSt.

[0079] <Thermoplastic Elastomer Compositions>

[0080] The thermoplastic elastomer composition of the present invention comprises the above-mentioned propylene polymer (A), and, relative to 100 parts by weight of the propylene polymer (A), comprises the above-mentioned ethylene-α-olefin copolymer (B) in a range of 50 to 300 parts by weight, preferably 50 to 250 parts by weight, and more preferably 50 to 200 parts by weight, from the viewpoint of softness and scratch resistance; and, in a range of 50 to 280 parts by weight, preferably 60 to 280 parts by weight, and more preferably 80 to 280 parts by weight, from the viewpoint of moldability and heat resistance, comprises the above-mentioned softener (C); and, in a range of 90 to 400 parts by weight, preferably 95 to 350 parts by weight, and more preferably 100 to 280 parts by weight, the hydrogenated block copolymer (D) comprises.

[0081] Furthermore, in the thermoplastic elastomer composition of the present invention, in addition to the above-described components (B), (C), and (D), the above-described polyorganosiloxane (E) is preferably included in the range of 2 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 2 to 20 parts by mass relative to 100 parts by mass of the propylene polymer (A).

[0082] If the amount of polyorganosiloxane (E) is 2 parts by mass or more, the improvement effect on scratch resistance is sufficiently manifested; if it is 30 parts by mass or less, the dispersibility in the thermoplastic elastomer composition is excellent. In the thermoplastic elastomer composition of the present invention, from the viewpoint of moldability and scratch resistance, the mass ratio (C / B) of ethylene-α-olefin copolymer (B) to softener (C) is preferably greater than 0 and less than 3, more preferably 0.6 to 2.8, and even more preferably 0.7 to 2.5.

[0083] The thermoplastic elastomer compositions of the present invention preferably contain, as needed, the following organic peroxide (F) [hereinafter, sometimes referred to as "component (F)"].

[0084] The component (F) involved in this invention functions as a crosslinking initiator for components (A), (B), and (D) of the thermoplastic elastomer composition of this invention by subjecting the thermoplastic elastomer composition of this invention to dynamic heat treatment.

[0085] <Organic peroxides (F)>

[0086] Specific examples of the organic peroxides (F) involved in this invention include 1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-hexylperoxide)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-hexylperoxide)cyclohexane, 1,1-bis(tert-butylperoxide)cyclododecane, 1,1-bis(tert-butylperoxide)cyclohexane, 2,2-bis(tert-butylperoxide)octane, and n-butyl... Peroxy ketals such as butyl-4,4-bis(tert-butylperoxide)butane and n-butyl-4,4-bis(tert-butylperoxide)valerate; di-tert-butylperoxide, dicumyl peroxide, tert-butylcumyl peroxide, α,α'-bis(tert-butylperoxide-m-isopropyl)benzene, α,α'-bis(tert-butylperoxide)diisopropylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, etc. Dialkyl peroxides such as hexyne-3; peroxydiacyl peroxides such as acetyl peroxide, isobutyryl peroxide, octyl peroxide, decyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and m-toluyl peroxide; tert-butyl peracetate, tert-butyl perisobutyrate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl perlaurate, and benzoyl peroxide. Peroxide esters include tert-butyl phthalate, di-tert-butyl isophthalate peroxide, 2,5-dimethyl-2,5-di(benzoyl peroxide)hexane, tert-butyl maleic acid peroxide, tert-butyl isopropyl carbonate peroxide, cumyl peroxy octanoate, etc.; and hydrogen peroxides such as tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl peroxide, etc.

[0087] Among these components (F), from the viewpoint of thermal decomposition temperature and crosslinking performance, 1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane, di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, and 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexyn-3 are preferred.

[0088] The component (F) involved in this invention can be a single type or two or more types used together.

[0089] In the case where the thermoplastic elastomer composition of the present invention contains component (F), from the viewpoint of molding flowability, its content is preferably 2 to 6 parts by mass relative to 100 parts by mass of component (A), more preferably 2 to 4 parts by mass.

[0090] In the case where the thermoplastic elastomer composition of the present invention contains component (F), it is preferable to use the following crosslinking aid.

[0091] <Crosslinking aids>

[0092] The crosslinking aids involved in this invention include various known crosslinking aids, specifically monofunctional monomers and polyfunctional monomers. Such crosslinking aids can control the rate of the crosslinking reaction.

[0093] Examples of monofunctional monomers, preferably free radical polymerizable vinyl monomers, include aromatic vinyl monomers, unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile, acrylate monomers, methacrylate monomers, acrylic monomers, methacrylic acid monomers, maleic anhydride monomers, and N-substituted maleimide monomers.

[0094] Specific examples of monofunctional monomers include styrene, methylstyrene, chloromethylstyrene, hydroxystyrene, tert-butoxystyrene, acetoxystyrene, chlorostyrene, acrylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, maleic anhydride, methylmaleic anhydride, 1,2-dimethylmaleic anhydride, ethylmaleic anhydride, phenylmaleic anhydride, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-laurylmaleimide, and N-cetylmaleimide. Among these, styrene, acrylonitrile, methacrylonitrile, methyl acrylate, maleic anhydride, and N-methylmaleimide are preferred from the viewpoint of reactivity and versatility. These monofunctional monomers can be used individually or in combination of two or more.

[0095] A multifunctional monomer is a monomer having multiple free radical polymerizable functional groups as functional groups, preferably a monomer having vinyl groups. The number of functional groups in a multifunctional monomer is preferably two or three.

[0096] Specific examples of multifunctional monomers include divinylbenzene, triallyl isocyanurate, triallyl cyanurate, diacetone diacrylamide, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diisopropylbenzene, p-quinone dioxime, p,p'-dibenzoylquinone dioxime, phenylmaleimide, allyl methacrylate, N,N'-m-phenylene bismaleimide, diallyl phthalate, tetraallyloxyethane, 1,2-polybutadiene, etc., and more preferably divinylbenzene and triallyl isocyanurate. These multifunctional monomers can be used alone or in combination of two or more.

[0097] When the thermoplastic elastomer composition of the present invention contains a crosslinking aid, the amount is 1 to 100 parts by weight, preferably 1 to 50 parts by weight, relative to 100 parts by weight of component (F).

[0098] <Preparation method and physical properties of thermoplastic elastomer compositions>

[0099] By dynamically crosslinking the thermoplastic elastomer composition of the present invention, at least a portion of components (A), (B), and (D) contained in the thermoplastic elastomer composition are crosslinked. When performing dynamic crosslinking, it is preferable to perform dynamic heat treatment in the presence of component (F), or in the presence of component (F) and the crosslinking aid.

[0100] In this invention, "performing dynamic heat treatment" refers to mixing in a molten state.

[0101] Furthermore, for the thermoplastic elastomer compositions of the present invention, the composition before dynamic heat treatment is also referred to as "Composition 1", and the composition obtained after dynamic heat treatment is also referred to as "Composition 2".

[0102] The dynamic heat treatment in this invention is preferably carried out in a non-open apparatus, and more preferably in an inert gas atmosphere such as nitrogen or carbon dioxide. The heat treatment temperature is in the range of the melting point of component (A) to 300°C, typically 150–270°C, and preferably 170–250°C. The mixing time is typically 1–20 minutes, preferably 1–10 minutes. Furthermore, the applied shear force, if expressed as shear rate, is typically between 10 and 50,000 s. -1 Preferably 100 to 10,000 s -1 Within the range.

[0103] The Shore A hardness (10-second value) of composition 2 (measured according to JIS K 6253) is preferably 30 to 75, more preferably 40 to 73, and even more preferably 50 to 70.

[0104] If the Shore A hardness (10-second value) of composition 2 is within the above range, it is easy to form a molded body with a tactile feel, a high-end appearance, and scratch resistance.

[0105] Specifically, the Shore A hardness (10-second value) described above can be determined using the method described in the following examples.

[0106] From the perspective of making a composition with excellent formability, the melt flow rate of composition 2 (measured according to JIS K7210 method, 230°C, 1.2kg load) is preferably 0.1 to 100 g / 10 min, more preferably 5 to 90 g / 10 min, and even more preferably 10 to 80 g / 10 min.

[0107] In addition to the above-mentioned component (A), inorganic fillers, plasticizers, and other additives may be added to the thermoplastic elastomer composition of the present invention.

[0108] Examples of inorganic fillers include calcium carbonate, magnesium carbonate, silicon dioxide, carbon black, glass fiber, titanium dioxide, clay, mica, talc, magnesium hydroxide, and aluminum hydroxide.

[0109] Examples of plasticizers include polyethylene glycol, dioctyl phthalate (DOP), and other phthalates.

[0110] Other additives include, for example, organic / inorganic pigments such as carbon black, titanium dioxide, or phthalocyanine black; heat stabilizers such as 2,6-di-tert-butyl-4-methylphenol and n-octadecyl-3-(3,5'-di-tert-butyl-4-hydroxyphenyl)propionate; antioxidants such as trinonylphenyl phosphite and distearate pentaerythritol diphosphite; ultraviolet absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2,4-dihydroxybenzophenone; and bis-[2,2,6,6-tetramethyl-4-piperazine]. Light stabilizers such as [pyridyl] sebacate and tetrakis(2,2,6,6-tetramethyl-4-piperidinyl)-1,2,3,4-butanetetracarboxylate; flame retardants such as ammonium polyphosphate, trioctyl phosphate, and magnesium hydroxide; silicone oils such as dimethyl silicone oil and methylphenyl silicone oil; anti-blocking agents such as stearamide and erucamide; foaming agents such as sodium bicarbonate and N,N'-dinitrospentamethylenetetramine; antistatic agents such as glyceryl palmitate and glyceryl stearate; and antibacterial agents such as silver ion-supported zeolite and silver thiosulfate coordination compounds.

[0111] Molded Body

[0112] The molded articles involved in this invention are not particularly limited in that they contain the thermoplastic elastomer composition of this invention, and, depending on the application, can be molded articles obtained using any known molding method. Examples of molding methods include, for instance, compression molding, injection molding, extrusion molding, calendering, blow molding, vacuum molding, and compression molding. From the viewpoint of productivity and the ability to easily form complex shapes, injection molded articles obtained using injection molding are preferred.

[0113] The thermoplastic elastomer composition of the present invention has low hardness and is soft, and has excellent scratch resistance. Its application is not particularly limited. For example, as a molded body, it is suitable for various known applications such as automotive parts, civil / building materials, electrical / electronic parts, hygiene products, films / sheets, foams, and artificial leather. In particular, it is suitable for automotive parts such as automotive interior parts and surface materials such as artificial leather.

[0114] <Automotive Parts>

[0115] As automotive parts in which the molded articles of the present invention can be used, examples include weatherstripping, headliner materials, interior trim pieces, bumper trim strips, side trim strips, air spoilers, air duct hoses, cup holders, side brake levers, shift knob covers, seat adjustment knobs, door seals, wiring harness loops, rack and pinion boots, suspension cover boots, glass guides, inner waistline seals, roof guides, trunk lid seals, molded triangular window gaskets, corner trim strips, glass encapsulation, hood seals, glass guide channels, secondary seals, various gaskets, bumper components, body panels, side panels, glass guide channels, dashboard skins, door skins, headliner skins, weatherstripping materials, hoses, steering wheels, dust covers, wiring harness covers, seat adjuster covers, etc., among which the thermoplastic elastomer composition of the present invention can improve the feel and texture, and is therefore particularly preferred.

[0116] <Civil Engineering / Building Materials>

[0117] As the molded body of the present invention can be used in civil / building materials, such as foundation improvement sheets, water supply boards, noise reduction walls and other civil materials, building materials, various gaskets and sheets for civil / building, water-stopping materials, joint materials, window frames for buildings, etc., of which the thermoplastic elastomer composition of the present invention can improve the texture and feel, and is therefore particularly preferred.

[0118] <Electrical / Electronic Components>

[0119] As electrical / electronic components that can use the molded body of the present invention, examples include wire sheathing materials, connectors, caps, plugs, and other electrical / electronic components. The thermoplastic elastomer composition of the present invention is particularly preferred because it can improve the texture and feel.

[0120] <Household Items>

[0121] Examples of everyday items that can use the molded bodies involved in this invention include sports shoes soles, ski boots, tennis rackets, ski fasteners, baseball bat handles and other sporting goods, pen grips, toothbrush handles, comb brushes, fashion belts, various hats, shoe insoles and other miscellaneous items. The thermoplastic elastomer composition of this invention is particularly preferred because it can improve the texture and feel.

[0122] <Membranes / Sheets>

[0123] As a film / sheet that can be used with the molded body of the present invention, it can be used for, for example, infusion bags, medical containers, automotive interior and exterior materials, beverage bottles, clothing boxes, food packaging materials, food containers, cooking containers, tubes, transparent substrates, sealing materials, etc., and is particularly preferred because the thermoplastic elastomer composition of the present invention can improve the texture and feel.

[0124] <Artificial Leather>

[0125] As artificial leather that can be used in the molded articles of the present invention, it can be used for, for example, chair covers, bags, backpacks, athletic shoes, marathon shoes, running shoes and other sports shoes, clothing such as jackets and coats, belts, straps, ribbons, notebook covers, book covers, keychains, pencil cases, wallets, business card holders, monthly pass holders, etc., and is therefore particularly preferred because the thermoplastic elastomer composition of the present invention can improve the texture and feel of leather.

[0126] Example

[0127] The present invention will be further described in detail below based on embodiments, but the present invention is not limited to these embodiments in any way.

[0128] The test methods for each component of the raw materials used in the examples and comparative examples are as follows.

[0129] (1) Hydrogenation rate (%)

[0130] Hydrogenation rate was determined by nuclear magnetic resonance (NMR) spectroscopy. An NMR spectrometer (JEOL, JNM-LA400) was used as the measuring instrument, deuterated chloroform as the solvent, and tetramethylsilane (TMS) as the chemical shift reference. The determination was performed under the following conditions: sample concentration of 50 mg / mL, observation frequency of 400 MHz, pulse delay of 2.904 seconds, 64 scans, pulse width of 45°, and measurement temperature of 26 °C.

[0131] (2) Content of monomer units and bonding units

[0132] The contents of vinyl aromatic monomer units, ethylene monomer units, butene monomer units, and 1,4-, 1,2-, and 3,4-bond units of butadiene were determined by NMR. An NMR spectrometer (JEOL, JNM-LA400) was used as the measuring instrument, deuterated chloroform as the solvent, and tetramethylsilane (TMS) as the chemical shift reference. The determination was performed under the following conditions: sample concentration of 50 mg / mL, observation frequency of 400 MHz, pulse delay of 2.904 seconds, 64 scans, pulse width of 45°, and measurement temperature of 26 °C.

[0133] The mass fraction (mass%) of each structural unit contained in component (B) is determined by utilizing... 13 The value was determined by C-NMR measurements. Specifically, an ECX400P nuclear magnetic resonance spectrometer (manufactured by NEC Electronics Co., Ltd.) was used, under the following conditions: measurement temperature: 120°C, measurement solvent: o-dichlorobenzene / deuterated benzene = 4 / 1 (volume ratio), and cumulative measurements: 8000. The value was determined from the C-NMR values ​​of copolymer (B-1). 13 The C-NMR spectrum was calculated.

[0134] (3) Styrene polymer block content (Os value)

[0135] The styrene polymer block content was determined using the unhydrogenated copolymer and by the method described in IMKolthoff, et al., J. Polym. Sci. 1, 429 (1946) (osmium tetroxide decomposition method). For the decomposition of the unhydrogenated copolymer, a 0.1 g / 125 mL solution of osmium tetroxide was used. The styrene polymer block content was calculated using the following formula. The styrene polymer block content obtained at this point is referred to as the "Os value".

[0136] Styrene polymer block content (Os value; % by mass)

[0137] = [(mass of styrene polymer blocks in the copolymer before hydrogenation) / (mass of the copolymer before hydrogenation)] × 100

[0138] (4) Peak temperature of loss tangent (tanδ)

[0139] The results were obtained by measuring the viscoelastic spectrum using a viscoelasticity measuring and analytical apparatus (ARES, Ta Instruments). The measurements were performed under conditions of 0.1% strain and 1 Hz frequency.

[0140] The following polymers were used in the examples and comparative examples.

[0141] [Propylene polymer (A)]

[0142] As a propylene-based polymer (A-1), a propylene homopolymer (polypropylene PP) with a melt flow rate (MFR) of 2.0 g / 10 min under the conditions of 230°C and 2.16 kg load (manufactured by SunAllomer, a registered trademark) was used.

[0143] [Ethylene-α-olefin copolymer (B)]

[0144] As an ethylene-α-olefin copolymer (B-1), an ethylene-1-octene copolymer (manufactured by Dow Corning, trade name "ENGAGE 8842") was used. The copolymer had an ethylene content of 55% by mass and an octene content of 45% by mass, and the MFR was 1.0 g / 10 min, measured at a temperature of 190°C and a load of 2.16 kg.

[0145] [Softener (C)]

[0146] As a softener (C-1), a paraffin-based oil (manufactured by Idemitsu Kosan Co., Ltd., trade name "Diana ProcessOil PW-100") was used.

[0147] [Hydride of block copolymer (D)]

[0148] As the hydride (D) of the block copolymer, the hydride of the block copolymer manufactured by the method shown below was used.

[0149] [Preparation of hydride (D-1) of block copolymer]

[0150] (1) Preparation of hydrogenation catalyst

[0151] The hydrogenation catalyst used in the hydrogenation reaction of the block copolymer was prepared by the following method. In a reaction vessel purged with nitrogen, 1 L of dried and purified cyclohexane was added, along with 100 mmol of bis(cyclopentadienyl)titanium dichloride. While stirring thoroughly, a solution of n-hexane containing 200 mmol of trimethylaluminum was added, and the reaction was carried out at room temperature for about 3 days.

[0152] (2) Manufacturing of hydrides of block copolymers

[0153] Batch polymerization was performed using a 10L tank reactor equipped with a stirrer and jacket. First, 6.4L of cyclohexane and 75g of styrene were added. TMEDA was added pre-initially at 0.25 molar amounts of Li as the initiator for n-butyllithium, and Li was added as a 10 mmol amount. Polymerization was carried out at an initial temperature of 65°C. After polymerization, a cyclohexane solution (monomer concentration 22% by mass) containing 470g of butadiene and 380g of styrene was continuously fed into the reactor at a constant rate over 60 minutes. After polymerization, a cyclohexane solution (monomer concentration 22% by mass) containing 75g of styrene was added over 10 minutes to obtain the copolymer (D-1').

[0154] The obtained copolymer (D-1') has a styrene content of 53% by mass, a styrene polymer block content of 15% by mass, and a styrene content of 45% by mass, a butadiene content of 55% by mass, and a vinyl bond content of 23% in the copolymer block (i.e., the copolymer block containing conjugated diene monomer units and vinyl aromatic monomer units).

[0155] The aforementioned hydrogenation catalyst was added at 100 ppm per 100 parts by mass of polymer titanium to the obtained copolymer (D-1'), and hydrogenation was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 75 °C. Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was added as a stabilizer to the resulting polymer solution, yielding the hydride of the block copolymer (D-1).

[0156] The obtained hydride of the block copolymer (D-1) has a weight-average molecular weight of 160,000, and the hydrogenation rate of the double bonds in the butadiene contained in the hydride of the block copolymer (D-1) is 99%. In addition, one of the tanδ peaks obtained by viscoelasticity determination exists at -15℃.

[0157] [Polyorganosiloxane (E)]

[0158] As a polyorganosiloxane (E-1), a masterbatch consisting of 50% by mass of dimethylsiloxane and 50% by mass of polypropylene (manufactured by DuPont Toray Specialty Materials, trade name "MB50-001") was used.

[0159] [Organic peroxides (F)]

[0160] As an organic peroxide (F), a mixture of the following organic peroxide and the following crosslinking aid was used.

[0161] Organic peroxide: 100 parts by weight of 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane (manufactured by Nippon Oil & Fat Co., Ltd., trade name "PERHEXA 25B").

[0162] Crosslinking aid: Divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.; hereinafter referred to as "DVB") 15 parts by weight

[0163] <Example 1>

[0164] <Preparation of the Composition>

[0165] As the extruder, a twin-screw extruder (30mmφ, L / D=74; Kobe Steel, "KTX-30") with an oil injection port in the center of the barrel was used. Two screws with mixing sections before and after the injection port were used. The raw materials, excluding the softener listed in Table 1, were mixed at the composition ratios (parts by mass) shown in Table 1 and fed into the twin-screw extruder (barrel temperature 200°C) using a metering feeder. Then, the softener amount shown in Table 1 was injected through the injection port located in the center of the extruder using a pump, and melt extrusion was performed to obtain a thermoplastic elastomer composition.

[0166] <Manufacturing of Injection Molded Parts>

[0167] The injection molding machine used was the "M150CL-DM" manufactured by Meiki Seisakusho Co., Ltd. Molding conditions were set at a resin temperature of 220°C and a mold temperature of 40°C. Using a flat mold measuring 15cm x 9cm with a leather-textured finish (average arithmetic roughness Ra = 20μm), the thermoplastic elastomer composition obtained above was injection molded to produce injection-molded samples.

[0168] The physical properties of the obtained thermoplastic elastomer compositions and injection-molded samples were evaluated using the following methods. The results are shown in Table 1.

[0169] (1) MFR (g / 10 minutes)

[0170] The melt flow rate of the thermoplastic elastomer composition obtained above was measured according to JIS K7120 under conditions of 230°C and 1.2 kg load.

[0171] In addition, samples whose MFR cannot be measured due to being too high or too low are designated as unmeasurable.

[0172] (2) Shore A hardness test

[0173] A 2 mm thick pressed sheet was made from the thermoplastic elastomer composition obtained above, and a 6 mm thick laminate obtained by overlapping 3 of the pressed sheets was used as the test sample.

[0174] The test samples obtained above were tested using a Shore A hardness tester according to JIS K6253. After the pressure plate was brought into contact with the test piece, the value read after 10 seconds was set as the Shore A hardness (10-second value).

[0175] (3) Scratch resistance

[0176] For the injection-molded samples obtained above, a pen-type scratch hardness tester (Eriksen, 318 / 318S No. 2) was used to make 10 scratches each in the longitudinal and transverse directions under a load of 10 N. The scratches in the central grid area were visually observed and evaluated. The evaluation was performed according to the following criteria.

[0177] A: It is almost impossible to detect any change in appearance caused by the scratches.

[0178] B: I have made some slight observation of the changes in appearance caused by the scratches.

[0179] C: The appearance change caused by the scratches has been confirmed.

[0180] D: The appearance changes significantly due to scratches.

[0181] (4) Softness (softness / firmness)

[0182] Regarding softness (softness / hardness), the softness / hardness of the injection-molded samples obtained above was evaluated by pressing the surface with a finger according to the following criteria. The softness / hardness evaluation was conducted by three people, and the results were unanimous.

[0183] A: Good (It has a soft feel. The surface deforms clearly when pressed with a finger.)

[0184] B: Slightly undesirable (slightly hard. A slight deformation can be felt on the surface when pressed with a finger.)

[0185] C: Poor (It has a hard texture. No deformation can be felt on the surface when pressed with a finger.)

[0186] <Examples 2-4, Comparative Examples 1-6>

[0187] The raw materials used were changed to the formulations listed in Table 1. Otherwise, the samples were prepared and evaluated using the same method as in Example 1. The results are shown in Table 1.

[0188] Furthermore, in Comparative Example 4, due to an excessively low MFR, no injection-molded part could be obtained. Therefore, the evaluation of scratch resistance and softness using this injection-molded part sample could not be performed.

[0189] [Table 1]

[0190]

[0191] <Evaluation Results>

[0192] As shown in Table 1, it can be seen that the injection molded parts obtained from the thermoplastic elastomer compositions of Examples 1 to 4 not only have low hardness, but also excellent flowability, softness and scratch resistance.

[0193] On the other hand, in Comparative Examples 1, 2, 5, and 6, molded articles with good scratch resistance were not obtained. In Comparative Example 3, the hardness was too high, and a molded article with good softness that met the required performance was not obtained. In Comparative Example 4, due to the excessively low MFR, an injection molded article could not be obtained.

Claims

1. A thermoplastic elastomer composition, characterized in that, Includes the following (A) to (D), (A) Propylene polymer: 100 parts by weight (B) An ethylene-α-olefin copolymer comprising ethylene-derived units and α-olefin-derived units having 3 to 20 carbon atoms, wherein the ethylene-derived units comprise more than 80 mol% and less than 99 mol% of the ethylene-derived units: ranging from 122 to 200 parts by mass, wherein the total mass of the ethylene-derived units and the α-olefin-derived units having 3 to 20 carbon atoms is 100 mol%. (C) Softener: 50–280 parts by weight (D) Hydrogenates of block copolymers having at least one block with a conjugated diene monomer unit as the main body and at least one block with a vinyl aromatic monomer unit as the main body: in the range of 90 to 400 parts by mass.

2. The thermoplastic elastomer composition according to claim 1, comprising (E) polyorganosiloxane in the range of 2 to 30 parts by weight.

3. The thermoplastic elastomer composition according to claim 1 or 2, wherein the mass ratio of (C) to (B), i.e., (C) / (B), is greater than 0 and less than 3.

4. The thermoplastic elastomer composition according to claim 1 or 2, wherein the mass ratio of (C) to (B), i.e., (C) / (B), is 0.6 to 1.

86.

5. The thermoplastic elastomer composition according to claim 1 or 2, wherein the block of (D) with conjugated diene monomer units as the main body is a copolymer block containing conjugated diene monomer units as the main body and containing vinyl aromatic monomer units.

6. The thermoplastic elastomer composition according to claim 1 or 2, wherein it is formed by dynamic heat treatment.

7. The thermoplastic elastomer composition according to claim 6, wherein the melt flow rate of the composition at 230°C and 1.2 kg load is 0.1 to 30 g / 10 minutes.

8. The thermoplastic elastomer composition according to claim 1 or 2, wherein at least a portion of (B) is crosslinked.

9. An injection-molded article comprising the thermoplastic elastomer composition according to any one of claims 1 to 8.

10. An automotive interior component comprising the injection-molded body of claim 9.

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