Thermoplastic elastomer composition and use thereof

Abstract

To provide a thermoplastic elastomer composition having low hardness and being flexible, and exhibiting excellent scratch resistance.SOLUTION: The present invention pertains to a thermoplastic elastomer composition containing (A) to (D) below: (A) 100 pts.mass of a propylene polymer; (B) 50 to 300 pts.mass of an ethylene / α-olefin copolymer including units of ethylene and α-olefin having 3 to 20 carbon atoms; (C) 50 to 280 pts.mass of a softener; and (D) 90 to 400 pts.mass of a hydrogenated product of a block copolymer including at least one block mainly including a conjugated diene monomer unit and at least one block mainly including a vinyl aromatic monomer unit.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a thermoplastic elastomer composition and its uses.

Background Art

[0002] For interior skin materials such as automotive instrument panels and door trims, olefin-based thermoplastic elastomers may be used from the viewpoint of weight reduction of materials. To shape a sheet for an interior skin material made of an olefin-based thermoplastic elastomer into the shape of an instrument panel, door trim, etc., vacuum forming or injection molding is generally performed.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, there has been a demand for a material that is lower in hardness and softer than conventional thermoplastic elastomer compositions from the perspective of improving touch, while maintaining excellent scratch resistance. However, the thermoplastic elastomer compositions described in Patent Documents 1 and 2 are designed to have excellent scratch resistance at conventionally acceptable hardness levels, but their scratch resistance in the low hardness range that has been demanded in recent years is not sufficient, and further improvement is desired. An object of the present invention is to provide a thermoplastic elastomer composition that is low in hardness, soft, and excellent in scratch resistance.

Means for Solving the Problems

[0006] The present invention relates to a thermoplastic elastomer composition characterized by containing the following (A) to (D). (A) Polypropylene 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, (D) Hydrogenated product of a block copolymer having at least one block mainly composed of a conjugated diene monomer unit and at least one block mainly composed of a vinyl aromatic monomer unit: in the range of 90 to 400 parts by mass.

Effects of the Invention

[0007] The thermoplastic elastomer composition of the present invention is low in hardness, soft, and excellent in scratch resistance, and as a molded article, it is suitable for various known applications such as automotive parts, civil engineering and building materials, electrical and electronic parts, sanitary products, films and sheets, foams, artificial leather, etc., and can be particularly suitably used for automotive parts such as automotive interior parts and skin materials such as artificial leather.

Modes for Carrying Out the Invention

[0008] In this specification, the numerical range represented by using "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0009] <Propylene-based polymer (A)> The propylene-based polymer (A) [hereinafter may be 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 the structural unit derived from propylene among the structural units constituting the polymer is 50 mol% or more, and the content of the structural unit derived from propylene in component (A) is preferably 90 mol% or more.

[0010] Component (A) according to the present invention may be one kind or two or more kinds. Component (A) according to the present invention may be a propylene homopolymer or a copolymer of propylene and a comonomer other than propylene.

[0011] The structure of component (A) according to the present invention is not particularly limited. For example, the structural unit portion derived from propylene may have an isotactic structure, a syndiotactic structure, or an atactic structure, but an isotactic structure is preferable. In the case of the copolymer, it may be any of a random type [also referred to as random PP], a block type [also referred to as block PP: bPP], and a graft type.

[0012] The comonomer may be any other monomer copolymerizable with propylene, and α-olefins having 2 or 4 to 10 carbon atoms are preferable. Specifically, ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, etc. may be mentioned. Among these, ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene are preferable. The comonomer may be used alone or in combination of two or more.

[0013] From the viewpoint of flexibility and the like, the content of the structural unit derived from the comonomer in the copolymer is preferably 10 mol% or less. Component (A) according to the present invention may be synthesized by a conventionally known method or a commercially available product may be used. Examples of commercially available products include polypropylene from Sun Aroma Co., Ltd., Prime Polypro from Prime Polymer Co., Ltd., Novatec from Japan Polypropylene Corporation, SCG PP from SCG Plastics, etc.

[0014] Component (A) according to the present invention may be a crystalline polymer or an amorphous polymer. Here, crystallinity means that a melting point (Tm) is observed in differential scanning calorimetry (DSC).

[0015] When component (A) according to the present invention is a crystalline polymer, its melting point (in accordance with the measurement method of JIS K 7121) is preferably 100°C or higher, more preferably 120°C or higher, and preferably 180°C or lower, more preferably 170°C or lower from the viewpoints of heat resistance and the like.

[0016] The MFR of component (A) according to the present invention (in accordance with the measurement method of ASTM D 1238-65T, at 230°C and a load of 2.16 kg) is preferably 0.1 to 100 g / 10 min, more preferably 0.1 to 50 g / 10 min. When the MFR of component (A) according to the present invention is within the above range, a composition excellent in heat resistance, mechanical strength, fluidity, and moldability can be easily obtained.

[0017] <Ethylene·α-olefin copolymer (B)> 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 containing units derived from ethylene and units derived from an α-olefin having 3 to 20 carbon atoms.

[0018] The ethylene-α-olefin copolymer (B) according to the present invention [hereinafter, may be referred to as "component (B)"] can be obtained by copolymerizing at least ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of the α-olefin 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, 1-dodecene and the like. 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.

[0019] In the component (B) according to the present invention, the units derived from ethylene are usually in the range of 70 to 99 mol%, preferably 80 to 97 mol%, and the units derived from an α-olefin having 3 to 20 carbon atoms are in the range of 1 to 30 mol%, preferably 3 to 20 mol% [however, the total amount of the units derived from ethylene and the units derived from an α-olefin having 3 to 20 carbon atoms is 100 mol%]. The content ratio of the units derived from ethylene being within the above range is preferable for obtaining a thermoplastic elastomer composition excellent in mechanical strength.

[0020] In the component (B) according to the present invention, a monomer having an unsaturated bond can be copolymerized as necessary. Examples of the monomer having an unsaturated bond include conjugated diolefins such as butadiene and isoprene, non-conjugated diolefins such as 1,4-hexadiene; cyclic diene compounds such as dicyclopentadiene and norbornene derivatives; and acetylenes. Among these, from the viewpoint of flexibility, ethylidene norbornene (ENB) and dicyclopentadiene (DCP) are more preferred.

[0021] The component (B) according to the present invention usually has an MFR (ASTM D1238, load 2.16 kg, temperature 190 ° C) in the range of 0.1 to 20 g / 10 min, preferably 0.3 to 10 g / 10 min.

[0022] By setting the MFR within the above range, a thermoplastic elastomer composition with more excellent balance characteristics of fluidity and mechanical strength can be obtained. Component (B) according to the present invention usually has a density in the range of 0.8 to 0.9 g / cm 3 .

[0023] Component (B) according to the present invention can be produced, for example, using known polymerization catalysts such as Ziegler-Natta catalysts, vanadium-based catalysts, and metallocene catalysts. The polymerization method is not particularly limited, and it can be carried out by liquid-phase polymerization methods such as solution polymerization method, suspension polymerization method, bulk polymerization method, gas-phase polymerization method, or other known polymerization methods. Further, these copolymers are not limited as long as they exhibit the effects of the present invention and are also available as commercially available products. Examples of commercially available products include Engage 8842 [ethylene-1-octene copolymer] manufactured by Dow Chemical Company, Vistalon (registered trademark) manufactured by ExxonMobil Corporation, Esprene (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., Mitsui EPT (registered trademark), Toughmer P (registered trademark), Toughmer A (registered trademark) manufactured by Mitsui Chemicals, Inc., and the like.

[0024] <Softening agent (C)> The softening agent (C) [hereinafter, may be referred to as "component (C)" in some cases], which is one of the components of the thermoplastic elastomer composition of the present invention, is not particularly limited, but a plasticizer usually used for rubber can be used. From the viewpoint of compatibility with the above-mentioned propylene-based polymer (A) and ethylene-α-olefin copolymer (B), etc., a process oil composed of hydrocarbons such as paraffinic, naphthenic, and aromatic is preferable. Among these components (C), a process oil mainly composed of paraffinic hydrocarbons is preferable from the viewpoints of weather resistance and coloring property, and a process oil mainly composed of naphthenic hydrocarbons is preferable from the viewpoint of compatibility. From the viewpoint of heat and light stability, the content of aromatic hydrocarbons in the process oil is preferably 10% or less, more preferably 5% or less, and still more preferably 1% or less in terms of the carbon number ratio defined in ASTM D2140-97.

[0025] <Hydrogenated product of block copolymer (D)> The hydrogenated product (D) of the block copolymer, which is one of the components of the thermoplastic elastomer composition of the present invention (hereinafter, may be referred to as "component (D)" or "hydrogenated product (D)"), is a hydrogenated product of a block copolymer having at least one block mainly composed of a conjugated diene monomer unit and at least one block mainly composed of a vinyl aromatic monomer unit each.

[0026] Component (D) according to the present invention is obtained by hydrogenating (hereinafter, may be referred to as "hydrogenation") at least a part of the monomer units derived from the conjugated diene monomer. Here, the "vinyl aromatic monomer unit" means a structural unit of a polymer formed by polymerizing a vinyl aromatic compound as a monomer, and its structure is a molecular structure in which two carbons of a substituted ethylene group derived from a substituted vinyl group are bonding sites. Further, the "conjugated diene monomer unit" means a structural unit of a polymer formed by polymerizing a conjugated diene as a monomer, and its structure is a molecular structure in which two carbons of an olefin derived from the conjugated diene monomer are bonding sites.

[0027] In component (D) according to the present invention, "mainly composed of" means that in the copolymer block, the monomer units derived from the conjugated diene monomer (or vinyl aromatic monomer) are contained in the copolymer block in an amount of 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more. For example, a block mainly composed of a conjugated diene monomer unit means that the monomer units derived from the conjugated diene monomer are contained in the block in an amount of 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more.

[0028] In the component (D) according to the present invention, the vinyl aromatic monomer is not particularly limited, and examples thereof include vinyl aromatic compounds such as styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. These may be used alone or in combination of two or more. Among these, styrene is preferred from the viewpoint of economy.

[0029] In the component (D) according to the present invention, the conjugated diene monomer is a diolefin having a pair of conjugated double bonds, and examples thereof include 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 and the like. Among these, butadiene and isoprene are preferred from the viewpoint of economy. These may be used alone or in combination of two or more.

[0030] The arrangement of each block in the component (D) according to the present invention is not particularly limited, and an appropriate one can be adopted as appropriate. For example, when a polymer block composed of vinyl aromatic monomer units is represented by S and a polymer block composed of units in which at least a part of the conjugated diene monomer units is hydrogenated is represented by B, the hydrogenated product of this block copolymer is SB, S(BS) n1 (where n1 represents an integer of 1 to 3), S(BSB) n2 (where n2 represents an integer of 1 to 2), etc., linear block copolymers represented by, (SB) n3 X(where n3 represents an integer of 3 to 6. X represents a coupling agent residue such as silicon tetrachloride, tin tetrachloride, or a polyepoxy compound). Among these, linear block copolymers of the 2-type (diblock) of SB, the 3-type (triblock) of SBS, and the 4-type (tetrablock) of SBSB are preferred.

[0031] Here, the polymer block B may be a polymer block consisting only of conjugated diene monomer units, a polymer block mainly containing conjugated diene monomer units and containing vinyl aromatic monomer units (a polymer block in which conjugated diene monomer units and vinyl aromatic monomer units are copolymerized), and at least a part of the conjugated diene monomer units in any of the polymer blocks is hydrogenated.

[0032] The content of vinyl aromatic monomer units in the component (D) according to 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 viewpoints of heat resistance and dispersibility. By setting the content of vinyl aromatic monomer units to 30% by mass or more, the mechanical properties are further improved, and by setting it to 80% by mass or less, the low-temperature properties can be further improved.

[0033] The content of vinyl aromatic monomer units in the component (D) according to the present invention can be measured by nuclear magnetic resonance spectrum analysis (NMR). From the viewpoint of mechanical strength, the content of vinyl aromatic monomer unit blocks in the component (D) according to the present invention is preferably 10% by mass or more, and more preferably 10 to 40% by mass. Here, the content of vinyl aromatic compound polymer blocks in the component (D) is determined by the following formula using the mass of vinyl aromatic compound polymer blocks obtained by oxidatively decomposing the copolymer before hydrogenation with tert-butyl hydroperoxide using osmium tetroxide as a catalyst (the method described in I.M. Kolthoff, et al., J.Polym.Sci.1, 429(1946), hereinafter also referred to as the "osmium tetroxide decomposition method"). (Here, vinyl aromatic compound polymers having an average degree of polymerization of about 30 or less are excluded). Content of vinyl aromatic compound polymer block (% by mass) = (Mass of vinyl aromatic compound polymer block in copolymer before hydrogenation / Mass of copolymer before hydrogenation) × 100

[0034] When there are a plurality of polymer blocks in component (D) according to the present invention, the structures such as the molecular weight and composition of each may be the same or different. For example, in component (D), a hydrogenated copolymer block containing a conjugated diene monomer unit and a vinyl aromatic monomer unit, and a hydrogenated copolymer block mainly composed of a conjugated diene monomer unit may be present. The boundaries and ends of each block do not necessarily have to be clearly distinguished. The mode of distribution of the vinyl aromatic monomer units in each polymer block is not particularly limited, and they may be uniformly distributed, or may be distributed in a tapered shape, a stepped shape, a convex shape, or a concave shape. Further, a crystalline part may be present in the polymer block.

[0035] The mode of distribution of the vinyl units of the conjugated diene monomer units in each polymer block in component (D) according to the present invention is not particularly limited, and for example, the distribution may be biased. Examples of methods for controlling the distribution of vinyl units include adding a vinylating agent during polymerization and changing the polymerization temperature. Further, the distribution of the hydrogenation rate of the conjugated diene monomer units may be biased. The distribution of the hydrogenation rate can be controlled by methods such as changing the situation of the distribution of vinyl units, copolymerizing isoprene and butadiene, and then hydrogenating using a hydrogenation catalyst described later and utilizing the difference in the hydrogenation rates of isoprene units and butadiene units.

[0036] From the viewpoints of heat resistance, aging resistance, and weather resistance, in component (D) according to the present invention, preferably 75 mol% or more, more preferably 85 mol% or more, and still more preferably 97 mol% or more of the unsaturated bonds contained in the conjugated diene monomer units before hydrogenation are hydrogenated.

[0037] The hydrogenation catalyst used for hydrogenation is not particularly limited and is conventionally known (1) Supported heterogeneous hydrogenation catalysts in which metals such as Ni, Pt, Pd, and Ru are supported on carbon, silica, alumina, diatomaceous earth, etc., (2) So-called Ziegler-type hydrogenation catalysts using transition metal salts such as organic acid salts or acetylacetone salts of Ni, Co, Fe, Cr, etc. and reducing agents such as organic aluminum, (3) A homogeneous hydrogenation catalyst such as an organometallic complex such as an organometallic compound of Ti, Ru, Rh, Zr, etc. can be used.

[0038] As specific hydrogenation catalysts, the hydrogenation catalysts described in Japanese Patent Publication No. Sho 42-008704, Japanese Patent Publication No. Sho 43-006636, Japanese Patent Publication No. Sho 63-004841, Japanese Patent Publication No. Hei 01-037970, Japanese Patent Publication No. Hei 01-053851, Japanese Patent Publication No. Hei 02-009041, etc. can be used. Among these, preferred hydrogenation catalysts include reducing organometallic compounds such as titanocene compounds.

[0039] As the titanocene compound, for example, the compounds described in Japanese Patent Application Laid-Open No. Hei 08-109219 can be used. Specific examples include compounds having at least one or more ligands having a (substituted) cyclopentadienyl skeleton, indenyl skeleton, or fluorenyl skeleton such as bis(cyclopentadienyl)titanium dichloride and monopenta-methylcyclopentadienyltitanium trichloride.

[0040] Examples of the reducing organometallic compound include organoalkali metal compounds such as organolithium, organomagnesium compounds, organoaluminum compounds, organoboron compounds, organozinc compounds, etc.

[0041] The polymerization method of the block copolymer before hydrogenation in the component (D) according to the present invention is not particularly limited, and known methods can also be adopted. For example, the methods described in Japanese Patent Publication No. Sho 36-019286, Japanese Patent Publication No. Sho 43-017979, Japanese Patent Publication No. Sho 46-032415, Japanese Patent Publication No. Sho 49-036957, Japanese Patent Publication No. Sho 48-002423, Japanese Patent Publication No. Sho 48-004106, Japanese Patent Publication No. Sho 56-028925, Japanese Patent Application Laid-Open No. Sho 59-166518, Japanese Patent Application Laid-Open No. Sho 60-186577, etc. can be mentioned.

[0042] Optionally, component (D) may have a polar group. Examples of the polar group include a hydroxyl group, a carboxyl group, a carbonyl group, a thiocarbonyl group, an acid halide group, an acid anhydride group, a thiocarboxylic acid group, an aldehyde group, a thioaldehyde group, a carboxylic acid ester group, an amide group, a sulfonic acid group, a sulfonic acid ester group, a phosphoric acid group, a phosphoric acid ester group, an amino group, an imino group, a nitrile group, a pyridyl group, a quinoline group, an epoxy group, a thioepoxy group, a sulfide group, an isocyanate group, an isothiocyanate group, a silicon halide group, an alkoxysilicon group, a tin halide group, a boronic acid group, a boron-containing group, a boronate group, an alkoxytin group, a phenyltin group, etc.

[0043] The vinyl bond content in the conjugated diene monomer unit in the block copolymer before hydrogenation in component (D) according to the present invention is preferably 5 mol% or more from the viewpoints of flexibility and scratch resistance, and preferably 70 mol% or less from the viewpoints of productivity, elongation at break, and scratch resistance. The vinyl bond content in the conjugated diene monomer unit is more preferably 10 to 50 mol%, still more preferably 10 to 30 mol%, and even more preferably 10 to 25 mol%.

[0044] Here, the vinyl bond content means the ratio of those incorporated by 1,2-bond and 3,4-bond among the bonding modes of 1,2-bond, 3,4-bond, and 1,4-bond of the conjugated diene before hydrogenation. The vinyl bond content can be measured by NMR.

[0045] The weight-average molecular weight of component (D) before crosslinking is not particularly limited, but from the viewpoint of scratch resistance, it is preferably 50,000 or more, and from the viewpoint of molding fluidity, it is preferably 400,000 or less, 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 by gel permeation chromatography (GPC; manufactured by Shimadzu Corporation, apparatus name "LC-10"), column: TSKgel GMHXL (4.6 mm ID × 30 cm, 2 pieces) using tetrahydrofuran (1.0 mL / min) as the solvent under the condition of an oven temperature of 40°C. The weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) are calculated as polystyrene-equivalent molecular weights.

[0046] From the viewpoint of abrasion resistance, the block mainly composed of the conjugated diene monomer unit of component (D) according to the present invention is preferably a copolymer block containing mainly the conjugated diene monomer unit and containing the vinyl aromatic monomer unit.

[0047] Component (D) according to the present invention is not particularly limited, and the above-mentioned conjugated diene monomer and vinyl aromatic monomer can be used. Among them, from the viewpoint of the balance between mechanical strength and impact resistance, preferred combinations include a block containing butadiene units and styrene units, a block containing isoprene units and styrene units, and the like.

[0048] Component (D) according to the present invention only needs to contain at least mainly the conjugated diene monomer unit, and the content of each monomer is not particularly limited. In particular, from the viewpoint of the balance between mechanical strength and impact resistance, the content of the vinyl aromatic monomer unit 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.

[0049] <Polyorganosiloxane (E)> One of the components that may be included in the thermoplastic elastomer composition of the present invention, polyorganosiloxane (E) [hereinafter, may be referred to as "component (E)"], is not particularly limited in structure, but from the viewpoints of abrasion resistance and touch feeling, it preferably has a linear, branched, or crosslinked polymer structure.

[0050] Component (E) according to the present invention is not particularly limited, and known ones can also be used. Preferred polyorganosiloxanes are polymers containing siloxane units having substituents such as alkyl groups, vinyl groups, and aryl groups. Among these, polyorganosiloxanes having an alkyl group are particularly preferred, and polyorganosiloxanes having a methyl group are more preferred.

[0051] Specific examples of the polyorganosiloxane having a methyl group include, for example, polydimethylsiloxane, polymethylphenylsiloxane, polymethylhydrogensiloxane, and the like. Among these, polydimethylsiloxane is preferred.

[0052] The kinematic viscosity of component (E) according to the present invention is not particularly limited, but from the viewpoints of abrasion resistance and scratch resistance, the kinematic viscosity (25 ° C) defined in JIS Z8803 is preferably 5000 centistokes (cSt) or more. Also, from the viewpoints that the dispersibility of component (E) in the obtained thermoplastic elastomer composition tends to improve, the appearance is excellent, and the quality stability during melt extrusion also tends to further improve, the kinematic viscosity of component (E) is preferably less than 3,000,000 cSt. The kinematic viscosity of component (E) is more preferably 10,000 cSt or more and less than 3,000,000 cSt, and even more preferably 50,000 cSt or more and less than 3,000,000 cSt.

[0053] <Thermoplastic Elastomer Composition> The thermoplastic elastomer composition of the present invention contains, with respect to 100 parts by mass of the propylene-based polymer (A), the ethylene-α-olefin copolymer (B) in an amount of 50 to 300 parts by mass, preferably 50 to 250 parts by mass, more preferably 50 to 200 parts by mass from the viewpoints of flexibility and scratch resistance; the softening agent (C) in an amount of 50 to 280 parts by mass, preferably 60 to 280 parts by mass, more preferably 80 to 280 parts by mass from the viewpoints of moldability and heat resistance; and the hydrogenated product (D) of the block copolymer in an amount of 90 to 400 parts by mass, preferably 95 to 350 parts by mass, more preferably 100 to 280 parts by mass from the viewpoints of moldability and scratch resistance.

[0054] Further, the thermoplastic elastomer composition of the present invention preferably contains, with respect to 100 parts by mass of the propylene-based polymer (A), the polyorganosiloxane (E) in an amount of 2 to 30 parts by mass, more preferably 2 to 25 parts by mass, still more preferably 2 to 20 parts by mass, in addition to the above components (B), (C) and (D).

[0055] When the blending amount of the polyorganosiloxane (E) is 2 parts by mass or more, the effect of improving scratch resistance is sufficiently exhibited, and when it is 30 parts by mass or less, the dispersibility in the thermoplastic elastomer composition is excellent. From the viewpoints of moldability and scratch resistance, the thermoplastic elastomer composition of the present invention preferably has a mass ratio (C / B) of the ethylene-α-olefin copolymer (B) to the softening agent (C) that exceeds 0 and is less than 3, more preferably 0.6 to 2.8, still more preferably 0.7 to 2.5.

[0056] The thermoplastic elastomer composition of the present invention preferably contains the following organic peroxide (F) [hereinafter, may be referred to as "component (F)"] as needed. The component (F) according to the present invention acts as a crosslinking initiator or the like for the components (A), (B) and (D) which are components of the thermoplastic elastomer composition of the present invention by dynamically heat-treating the thermoplastic elastomer composition of the present invention.

[0057] 〈Organic peroxide (F)〉 Specific examples of the organic peroxide (F) according to the present invention include peroxyketals such as 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)octane, n-butyl-4,4-bis(t-butylperoxy)butane, n-butyl-4,4-bis(t-butylperoxy)valerate; dialkyl peroxides such as di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, α,α'-bis(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3; diacyl peroxides such as acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-trioil peroxide; peroxy esters such as t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, cumylperoxyoctate; hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl peroxide, and the like.

[0058] Among these components (F), from the viewpoints of thermal decomposition temperature, crosslinking performance, etc., 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3 are preferred.

[0059] The component (F) according to the present invention may be used alone or in combination of two or more. When the thermoplastic elastomer composition of the present invention contains the component (F), its content is preferably 2 to 6 parts by mass, more preferably 2 to 4 parts by mass, from the viewpoint of molding fluidity, based on 100 parts by mass of the component (A). When the thermoplastic elastomer composition of the present invention contains the component (F), it is preferable to use the following crosslinking aids in combination.

[0060] 〈Crosslinking Aids〉 The crosslinking aids according to the present invention include various known crosslinking aids, specifically, monofunctional monomers and polyfunctional monomers. Such crosslinking aids can control the crosslinking reaction rate.

[0061] As the monofunctional monomer, for example, radically polymerizable vinyl monomers are preferred, and aromatic vinyl monomers, unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile, acrylic acid ester monomers, methacrylic acid ester monomers, acrylic acid monomers, methacrylic acid monomers, maleic anhydride monomers, N-substituted maleimide monomers, etc. may be mentioned.

[0062] Specific examples of monofunctional monomers include, for example, 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, N-cetylmaleimide, etc. Among these, from the viewpoints of ease of reaction and versatility, styrene, acrylonitrile, methacrylonitrile, methyl acrylate, maleic anhydride, N-methylmaleimide, etc. are preferred. These monofunctional monomers may be used alone or in combination of two or more.

[0063] The polyfunctional monomer is a monomer having a plurality of radically polymerizable functional groups as functional groups, and a monomer having a vinyl group is preferred. The number of functional groups of the polyfunctional monomer is preferably 2 or 3.

[0064] Specific examples of the polyfunctional monomer 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, diisopropenylbenzene, p-quinone dioxime, p,p'-dibenzoylquinone dioxime, phenylmaleimide, allyl methacrylate, N,N'-m-phenylene bismaleimide, diallyl phthalate, tetraallyloxyethane, 1,2-polybutadiene, etc. are preferred, and divinylbenzene and triallyl isocyanurate are more preferred. These polyfunctional monomers may be used alone or in combination of two or more. When the thermoplastic elastomer composition of the present invention contains a crosslinking aid, it is 1 to 100 parts by mass, preferably 1 to 50 parts by mass, based on 100 parts by mass of component (F).

[0065] <Manufacturing Method and Physical Properties of Thermoplastic Elastomer Composition> By dynamically crosslinking the thermoplastic elastomer composition of the present invention, at least a part of component (A), component (B), and component (D) contained in the thermoplastic elastomer composition is crosslinked. When performing dynamic crosslinking, it is preferable to perform dynamic heat treatment in the presence of the component (F) or in the presence of the component (F) and the crosslinking aid.

[0066] In the present invention, "performing dynamic heat treatment" means kneading in a molten state. Note that the composition before dynamic heat treatment of the thermoplastic elastomer composition of the present invention is also referred to as "Composition 1", and the composition obtained by dynamic heat treatment is also referred to as "Composition 2".

[0067] The dynamic heat treatment in the present invention is preferably performed in a non-open type apparatus and preferably in an inert gas atmosphere such as nitrogen or carbon dioxide gas. The temperature of the heat treatment is in the range from the melting point of component (A) to 300 °C, usually 150 to 270 °C, preferably 170 to 250 °C. The kneading time is usually 1 to 20 minutes, preferably 1 to 10 minutes. Also, the applied shear force is usually in the range of 10 to 50,000 s -1 , preferably 100 to 10,000 s -1 in terms of shear rate.

[0068] The Shore A hardness (10-second value) (in accordance with the measurement method of JIS K 6253) of Composition 2 is preferably 30 to 75, more preferably 40 to 73, and even more preferably 50 to 70.

[0069] When the Shore A hardness (10-second value) of Composition 2 is within the above range, a molded article having design properties such as touch feeling and high-class appearance and scratch resistance can be easily formed. Specifically, the Shore A hardness (10-second value) can be measured by the method described in the following examples.

[0070] The melt flow rate of Composition 2 (in accordance with the measurement method of JIS K 7210, at 230°C and a load of 1.2 kg) 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 from the viewpoint of achieving a composition with excellent moldability.

[0071] In addition to the above component (A) and the like, the thermoplastic elastomer composition of the present invention may be added with an inorganic filler, a plasticizer, and other additives. Examples of the inorganic filler include calcium carbonate, magnesium carbonate, silica, carbon black, glass fiber, titanium oxide, clay, mica, talc, magnesium hydroxide, aluminum hydroxide, and the like.

[0072] Examples of the plasticizer include polyethylene glycol, phthalic acid esters such as dioctyl phthalate (DOP), and the like. Examples of other additives include organic and inorganic pigments such as carbon black, titanium dioxide, or phthalocyanine black; heat stabilizers such as 2,6-di-t-butyl-4-methylphenol and n-octadecyl-3-(3,5'-di-t-butyl-4-hydroxyphenyl) propionate; antioxidants such as trisnonylphenyl phosphite and distearyl pentaerythritol diphosphite; ultraviolet absorbers such as 2-(2'-hydroxy-5'-methylphenyl) benzotriazole and 2,4-dihydroxybenzophenone; light stabilizers such as bis-[2,2,6,6-tetramethyl-4-piperidinyl] 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; antiblocking agents such as stearic acid amide and erucic acid amide; foaming agents such as sodium bicarbonate and N,N'-dinitrosopentamethylenetetramine; antistatic agents such as monoglyceryl palmitate and monoglyceryl stearate; antibacterial agents such as silver ion-supported zeolite and thiosulfite silver complex, and the like.

[0073] ≪Molded article≫ The molded article according to the present invention is not particularly limited as long as it contains the thermoplastic elastomer composition of the present invention, and is a molded article molded by any known molding method according to the application. Examples of the molding method include, for example, press molding, injection molding method, extrusion molding method, calender molding method, hollow molding method, vacuum molding method, and compression molding method. From the viewpoints of productivity and easy formation of a complex shape, it is preferably an injection molded article molded by the injection molding method.

[0074] The thermoplastic elastomer composition of the present invention has low hardness and flexibility, is excellent in scratch resistance, and is not particularly limited in use. For example, as a molded article, it is suitable for various known applications such as automotive parts, civil engineering and building materials, electrical and electronic parts, sanitary products, films and sheets, foams, artificial leather, etc., and can be particularly suitably used for automotive parts such as automotive interior parts and skin materials such as artificial leather.

[0075] <Automobile parts> Examples of automobile parts that can use the molded body according to the present invention include, for example, weather strips, ceiling materials, interior seats, bumper moldings, side moldings, air spoilers, air duct hoses, cup holders, side brake grips, shift knob covers, seat adjustment knobs, flapper door seals, wire harness grommets, rack and pinion boots, suspension cover boots, glass guides, inner belt line seals, roof guides, trunk lid seals, molded dead quarter window gaskets, corner moldings, glass encapsulations, hood seals, glass run channels, secondary seals, various packings, bumper parts, body panels, side shields, glass run channels, instrument panel skins, door skins, ceiling skins, weather strip materials, hoses, steering wheels, boots, wire harness covers, seat adjuster covers, etc. Among them, the thermoplastic elastomer composition of the present invention can improve the texture and touch, so it is particularly preferable.

[0076] <Civil engineering and building materials> Examples of civil engineering and building materials that can use the molded body according to the present invention include, for example, soil improvement sheets, water supply plates, civil engineering materials and building materials such as noise prevention walls, various gaskets and sheets for civil engineering and construction, water stop materials, joint materials, building window frames, etc. Among them, the thermoplastic elastomer composition of the present invention can improve the texture and touch, so it is particularly preferable.

[0077] <Electrical and electronic parts> Examples of electrical and electronic parts that can use the molded body according to the present invention include, for example, electrical and electronic parts such as wire coating materials, connectors, caps, plugs, etc. Among them, the thermoplastic elastomer composition of the present invention can improve the texture and touch, so it is particularly preferable.

[0078] <Daily necessities> Examples of the daily necessities that can use the molded article according to the present invention include sports goods such as sports shoe soles, ski boots, tennis rackets, bindings for ski boards, and bat grips, and miscellaneous goods such as pen grips, toothbrush grips, hairbrushes, fashion belts, various caps, and shoe insoles. Among them, the thermoplastic elastomer composition of the present invention is particularly preferable because it can improve the texture and touch.

[0079] 〈Film / Sheet〉 Examples of the film / sheet that can use the molded article according to the present invention include infusion bags, medical containers, interior and exterior automotive materials, beverage bottles, clothing cases, food packaging materials, food containers, retort containers, pipes, transparent substrates, and sealants. Among them, the thermoplastic elastomer composition of the present invention is particularly preferable because it can improve the texture and touch.

[0080] 〈Artificial Leather〉 Examples of the artificial leather that can use the molded article according to the present invention include chair covers, bags, school bags, sports shoes such as track and field shoes, marathon shoes, and running shoes, and clothing such as jumpers and coats, belts, sashes, ribbons, notebook covers, book covers, key holders, pen cases, wallets, business card holders, and calendar holders. Among them, the thermoplastic elastomer composition of the present invention is particularly preferable because it can improve the texture and touch of leather.

Examples

[0081] Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples at all. The test methods for the respective components of the raw materials used in the examples and comparative examples are as follows.

[0082] (1) Hydrogenation rate (%) The hydrogen addition rate was measured by nuclear magnetic resonance spectrum analysis (NMR). A nuclear magnetic resonance measuring apparatus (manufactured by JEOL, model name "JNM-LA400") was used as the measuring instrument, deuterated chloroform was used as the solvent, and tetramethylsilane (TMS) was used as the chemical shift standard. The measurement was carried out under the conditions of a sample concentration of 50 mg / mL, an observation frequency of 400 MHz, a pulse delay of 2.904 seconds, a scan number of 64 times, a pulse width of 45°, and a measurement temperature of 26°C.

[0083] (2) Contents of monomer units and bonding units The contents of vinyl aromatic monomer units, ethylene monomer units, butylene monomer units, 1,4-bonding units, 1,2-bonding units, and 3,4-bonding units of butadiene were measured by NMR. A nuclear magnetic resonance measuring apparatus (manufactured by JEOL, model name "JNM-LA400") was used as the measuring instrument, deuterated chloroform was used as the solvent, and tetramethylsilane (TMS) was used as the chemical shift standard. The measurement was carried out under the conditions of a sample concentration of 50 mg / mL, an observation frequency of 400 MHz, a pulse delay of 2.904 seconds, a scan number of 64 times, a pulse width of 45°, and a measurement temperature of 26°C.

[0084] The mass fraction (mass %) of each constituent unit contained in component (B) was 13 determined from the measurement value by C-NMR. Specifically, using an ECX400P type nuclear magnetic resonance apparatus (manufactured by JEOL Ltd.), under the conditions of a measurement temperature of 120°C, a measurement solvent of orthodichlorobenzene / deuterated benzene = 4 / 1 (volume ratio), and an integration number of 8000 times, for the copolymer (B-1) 13 calculated from the C-NMR spectrum.

[0085] (3) Styrene polymer block content (Os value) The styrene polymer block content was measured by the method (osmium tetroxide decomposition method) described in I.M. Kolthoff, et al., J. Polym. Sci. 1, 429 (1946) using the copolymer before hydrogenation. For the decomposition of the copolymer before hydrogenation, a 0.1 g / 125 mL tert-butanol solution of osmium acid was used. The styrene polymer block content was calculated by the following formula. The styrene polymer block content obtained here is referred to as the "Os value". Styrene polymer block content (Os value; mass%) =[(mass of styrene polymer block in the copolymer before hydrogenation) / (mass of the copolymer before hydrogenation)] × 100

[0086] (4) Peak temperature of loss tangent (tanδ) It was determined by measuring the viscoelastic spectrum using a viscoelastic measurement and analysis device (ARES, manufactured by Ta Instruments). The measurement was carried out under the conditions of a strain of 0.1% and a frequency of 1 Hz.

[0087] In the examples and comparative examples, the following polymers were used. [Propylene-based polymer (A)] As the propylene-based polymer (A-1), a propylene homopolymer (homo-PP) (trade name Sun Allomer (registered trademark) PL400A, manufactured by Sun Allomer Co., Ltd.) with a melt flow rate (MFR) of 2.0 g / 10 min under the conditions of 230 °C and a load of 2.16 kg was used.

[0088] [Ethylene·α-olefin copolymer (B)] As the ethylene·α-olefin copolymer (B-1), an ethylene·1-octene copolymer (manufactured by Dow Chemical Company, trade name "Engage 8842") was used. The ethylene content of the copolymer is 55 mass%, the octene content is 45 mass%, and the MFR measured under the conditions of a temperature of 190 °C and a load of 2.16 kg is 1.0 g / 10 min.

[0089] [Softening agent (C)] As the softening agent (C-1), a paraffin oil (manufactured by Idemitsu Kosan Co., Ltd., trade name "Diana Process Oil PW-100") was used.

[0090] [Hydrogenated product (D) of block copolymer] As the hydrogenated product (D) of the block copolymer, a hydrogenated product of the block copolymer produced by the method shown below was used.

[0091] [Production of hydrogenated product (D-1) of block copolymer] (1) Preparation of hydrogenation catalyst The hydrogenation catalyst used for the hydrogenation reaction of the block copolymer was prepared by the following method. 1 L of dried and purified cyclohexane was charged into a reaction vessel purged with nitrogen, 100 mmol of bis(cyclopentadienyl)titanium dichloride was added, and while stirring sufficiently, an n-hexane solution containing 200 mmol of trimethylaluminum was added, and the mixture was reacted at room temperature for about 3 days.

[0092] (2) Production of hydrogenated product of block copolymer Batch polymerization was carried out using a stirred apparatus with an internal volume of 10 L and a jacketed tank reactor. First, 6.4 L of cyclohexane and 75 g of styrene were added, TMEDA was added in advance so as to be 0.25 times the molar number of Li of n-butyllithium, and 10 mmol was added as the molar number of Li of the n-butyllithium initiator, and polymerization was carried out at an initial temperature of 65 °C. After the polymerization was completed, a cyclohexane solution (monomer concentration: 22% by mass) containing 470 g of butadiene and 380 g of styrene was continuously fed to the reactor at a constant rate over 60 minutes. After the polymerization was completed, a cyclohexane solution (monomer concentration: 22% by mass) containing 75 g of styrene was added over 10 minutes to obtain a copolymer (D-1').

[0093] The styrene content in the obtained copolymer (D-1') was 53% by mass, the styrene polymer block content was 15% by mass, the styrene content in the copolymer block (i.e., the copolymer block containing a conjugated diene monomer unit and a vinyl aromatic monomer unit) was 45% by mass, the butadiene content was 55% by mass, and the vinyl bond content was 23%.

[0094] To the obtained copolymer (D-1'), 100 ppm of the above hydrogenation catalyst in terms of titanium per 100 parts by mass of the polymer was added, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 75°C. To the obtained polymer solution, 0.3 part by mass of octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate as a stabilizer was added per 100 parts by mass of the hydrogenated product of the block copolymer to obtain a hydrogenated product (D-1) of the block copolymer.

[0095] The weight average molecular weight of the obtained hydrogenated product (D-1) of the block copolymer was 160,000, and the hydrogenation rate in the double bond of butadiene contained in the hydrogenated product (D-1) of the block copolymer was 99%. Also, one of the tanδ peaks obtained by viscoelasticity measurement was present at -15°C.

[0096] 〔Polyorganosiloxane (E)〕 As the polyorganosiloxane (E-1), a masterbatch composed of 50% by mass of dimethylsiloxane and 50% by mass of polypropylene (manufactured by DuPont - Toray Specialty Materials Co., Ltd., trade name "MB50 - 001") was used.

[0097] 〔Organic peroxide (F)〕 As the organic peroxide (F), a mixture of the following organic peroxide and the following crosslinking coagent was used. Organic peroxide: 2,5 - dimethyl - 2,5 - bis(t - butylperoxy)hexane (manufactured by NOF Corporation, trade name "Perhexa 25B") 100 parts by mass Crosslinking coagent: Divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.; hereinafter referred to as "DVB") 15 parts by mass

[0098] <Example 1> <Production of composition> As the extruder, a twin-screw extruder (30 mm φ, L / D = 74; manufactured by Kobe Steel, Ltd., "KTX-30") having an oil inlet at the center of the barrel was used. As the screw, a two-strand screw having kneading parts before and after the inlet was used. After the raw materials other than the softening agent described in Table 1 were batch-mixed at the composition ratio (mass part ratio) shown in Table 1, they were introduced into a twin-screw extruder (cylinder temperature 200 ° C) with a metering feeder, and then, the softening agent in the amount shown in Table 1 was injected by a pump from the inlet at the center of the extruder, and melt extrusion was performed to obtain a thermoplastic elastomer composition.

[0099] <Manufacture of injection molded article> As the injection molding machine, "M150CL-DM" manufactured by Meiki Seisakusho Co., Ltd. was used. The molding conditions were carried out at a resin temperature of 220 ° C and a mold temperature of 40 ° C. Using a flat mold having a size of 15 cm in length × 9 cm in width and subjected to skin texture processing (average arithmetic roughness Ra = 20 μm), injection molding of the thermoplastic elastomer composition obtained above was performed to prepare an injection molded article sample. The physical properties of the obtained thermoplastic elastomer composition and injection molded article sample were evaluated by the following methods. The results are shown in Table 1.

[0100] (1) MFR (g / 10 min) The melt flow rate of the thermoplastic elastomer composition obtained above was measured under the conditions of 230 ° C and a load of 1.2 kg in accordance with JIS K7120. In addition, samples for which MFR measurement could not be performed because MFR was too high or too low were regarded as unmeasurable.

[0101] (2) Shore A hardness measurement A press sheet having a thickness of 2 mm was prepared from the thermoplastic elastomer composition obtained above, and a laminated sheet having a thickness of 6 mm obtained by stacking three of these press sheets was used as a measurement sample. The measurement sample obtained above was measured with a Shore A hardness tester in accordance with JIS K6253. After the pressure plate was brought into contact with the test piece, the value read 10 seconds later was taken as the Shore A hardness (10-second value).

[0102] (3) Scratch resistance For the injection molded body samples obtained above, a pencil-type scratch hardness tester (manufactured by Erichsen, 318 / 318S No.2) was used, and 10 scratches were made in each of the vertical and horizontal directions with a load of 10 N. The scratches in the central grid portion were visually observed and evaluated. The evaluation was carried out according to the following criteria. A: Almost no appearance change due to scratches is observed. B: Slight appearance change due to scratches is observed. C: Appearance change due to scratches is observed. D: Marked appearance change due to scratches is observed.

[0103] (4) Flexibility (hardness and softness feeling) For the flexibility (hardness and softness feeling) of the injection molded product samples obtained above, the hardness and softness feeling when pressing the surface with a finger was evaluated according to the following criteria. The evaluation of flexibility (hardness and softness feeling) was carried out by 3 people, and the evaluation results were unanimous. A: Good (with a soft feeling. The deformation of the surface can be clearly felt when pressing with a finger.) B: Slightly poor (slightly hard. Slight deformation of the surface can be felt when pressing with a finger.) C: Poor (with a hard feeling. No deformation of the surface can be felt when pressing with a finger.)

[0104] <Examples 2 to 4, Comparative Examples 1 to 6> Samples were prepared and evaluated in the same manner as in Example 1, except that the raw materials used were changed to the formulations described in Table 1. The results are shown in Table 1. Note that in Comparative Example 4, since the MFR was too low, an injection molded body could not be obtained. Therefore, the evaluation of scratch resistance and flexibility using the injection molded body samples could not be carried out.

[0105]

Table 1

[0106] <Evaluation Results> As shown in Table 1, it can be seen that the injection molded articles obtained from the thermoplastic elastomer compositions of Examples 1 to 4 are excellent in fluidity, flexibility, and scratch resistance while having low hardness.

[0107] On the other hand, in Comparative Examples 1, 2, 5, and 6, molded articles with good scratch resistance could not be obtained. In Comparative Example 3, the hardness was high, and a molded article with good flexibility satisfying the required performance could not be obtained. In Comparative Example 4, since the MFR was too low, an injection molded article could not be obtained.

[0108] [1] A thermoplastic elastomer composition characterized by containing the following (A) to (D); (A) Polypropylene 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, (D) Hydrogenated product of a block copolymer having at least one block mainly composed of a conjugated diene monomer unit and at least one block mainly composed of a vinyl aromatic monomer unit: in the range of 90 to 400 parts by mass. [2] The thermoplastic elastomer composition according to [1] above, containing polyorganosiloxane in the range of 2 to 30 parts by mass. [3] The thermoplastic elastomer composition according to [1] or [2] above, wherein the mass ratio (C / B) of (B) to (C) exceeds 0 and is less than 3. [4] The thermoplastic elastomer composition according to any one of [1] to [3] above, wherein the block mainly composed of a conjugated diene monomer unit in (D) is a copolymer block mainly composed of a conjugated diene monomer unit and containing a vinyl aromatic monomer unit. [5] The thermoplastic elastomer composition according to any one of [1] to [4] above, which is dynamically heat-treated. [6] The thermoplastic elastomer composition according to any one of [1] to [5] above, wherein at least a part of (B) is crosslinked. [7] An injection molded article comprising the thermoplastic elastomer composition according to any one of [1] to [6] above. [8] An automotive interior part made of the injection molded article according to [7] above.

Claims

【Claim 1】 A thermoplastic elastomer composition comprising the following (A) to (D); (A) A propylene-based polymer: 100 parts by mass, (B) An ethylene / α-olefin copolymer containing ethylene and an α-olefin unit having 3 to 20 carbon atoms: in the range of 50 to 300 parts by mass, (C) A softening agent: in the range of 50 to 280 parts by mass, (D) A hydrogenated product of a block copolymer having at least one block mainly composed of a conjugated diene monomer unit and at least one block mainly composed of a vinyl aromatic monomer unit: in the range of 90 to 400 parts by mass.

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