Thermoplastic elastomer composition and molded article made from the same

Abstract

A thermoplastic elastomer composition that contains (A) 100 parts by mass of a polypropylene resin, (B) 40–80 parts by mass of an ethylene / α-olefin copolymer that includes ethylene units and C3–20 α-olefin units, (C) 80–200 parts by mass of a hydrogenated block copolymer that is a hydrogenate of a block copolymer that has at least one each of a block (c1) that is mainly conjugated diene monomer units and a block (c2) that is mainly vinyl aromatic monomer units, (D) 100–250 parts by mass of a softener that is no more than 29% a component (R) that has a relative molecular weight in terms of polystyrene of no more than 600 as measured by gel permeation chromatography (GPC), and (E) 5–20 parts by mass of a polyorganosiloxane. At least a portion of the thermoplastic elastomer composition is cross-linked.

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic elastomer composition and a molded article made from the same. [Background technology]

[0002] Olefin-based thermoplastic elastomers are lightweight, easily recyclable, and do not emit toxic gases when incinerated, and therefore, from the perspectives of energy conservation, resource conservation, and more recently, global environmental protection, their applications are expanding to automobile parts, industrial machinery parts, electrical and electronic parts, building materials, etc. Here, in the field of automobile parts, in addition to olefin-based polymers, thermoplastic elastomers containing hydrogenated products of block copolymers containing vinyl aromatic monomers such as styrene are also widely used.

[0003] For example, Patent Document 1 discloses a thermoplastic elastomer containing an ethylene-α-olefin copolymer, a hydrogenated product of a block copolymer having conjugated diene monomer units and vinyl aromatic monomer units, and an olefin resin.

[0004] It is known that a softener such as a mineral oil softener is blended into this thermoplastic elastomer in order to increase flexibility and rubber elasticity.Patent Document 2 discloses a thermoplastic elastomer obtained by crosslinking a composition containing a polypropylene resin, a hydrogenated product of a block copolymer having conjugated diene monomer units and vinyl aromatic monomer units, a softener, and polyorganosiloxane.

[0005] Patent Document 3 discloses that excellent fogging resistance and gloss can be obtained by using a mineral oil softener having a specific evaporation loss and kinematic viscosity in a fully or partially crosslinked olefin-based thermoplastic elastomer composition comprising a crystalline polyolefin, an olefin-based copolymer rubber, and a paraffin-based mineral oil softener.

[0006] Although Patent Documents 1 and 2 refer to the use of softeners, they do not disclose any effect that the type of softener used has on the physical properties of the thermoplastic elastomer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2010 / 067564 [Patent Document 2] WO2011 / 155571 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-294714 Summary of the Invention [Problem to be solved by the invention]

[0008] Various attempts have been made to reduce the fogging phenomenon in olefin-based thermoplastic elastomers containing softeners. However, in recent years, environmental considerations have necessitated the reduction of volatile organic compounds (VOCs), necessitating further reduction in volatile components and improvement in fogging resistance. Such reduction in volatile components and improvement in fogging resistance are particularly required for automotive interior materials. However, it is known that thermoplastic elastomers with improved fogging resistance often suffer from impaired moldability, and there is a need for thermoplastic elastomers that can achieve both fogging resistance and moldability.

[0009] Therefore, an object of the present invention is to provide a thermoplastic elastomer and a molded article thereof that have improved fogging properties while maintaining a certain level of moldability. [Means for solving the problem]

[0010] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a softener in a thermoplastic elastomer containing a softener that has a low content of components with low relative molecular weights in terms of polystyrene, and have thus completed the present invention.

[0011] That is, the present invention relates to the following [1] to

[10] .

[0012] [1] A thermoplastic elastomer composition comprising the following components (A) to (E), which is at least partially crosslinked:

[0013] (A) 100 parts by mass of polypropylene resin; (B) 40 to 80 parts by mass of an ethylene-α-olefin copolymer containing ethylene units and α-olefin units having 3 to 20 carbon atoms; (C) 80 to 200 parts by mass of a hydrogenated block copolymer which is a hydrogenated product of a block copolymer having at least one block (c1) mainly composed of conjugated diene monomer units and at least one block (c2) mainly composed of vinyl aromatic monomer units; (D) 100 to 250 parts by mass of a softener, in which the proportion (R) of components having a relative molecular weight of 600 or less in terms of polystyrene, as measured by gel permeation chromatography (GPC), is 29% or less; (E) Polyorganosiloxane: 5 to 20 parts by mass.

[0014] [2] The kinematic viscosity of the softener (D) at 40°C is 300mm 2 / s or less of the thermoplastic elastomer composition according to [1].

[0015] [3] The thermoplastic elastomer composition according to [1] or [2], wherein the ratio (R) is 25% or less.

[0016] [4] The thermoplastic elastomer composition according to any one of [1] to [3], wherein the softener (D) has an evaporation loss of 0.2% by mass or less at 200° C. and normal pressure for 1 hour.

[0017] [5] The thermoplastic elastomer composition according to any one of [1] to [4], which satisfies the following requirements (1) to (3):

[0018] (1) The melt flow rate (MFR, 230°C, 1.2 kg load) measured in accordance with ASTM D1238 is 30 to 100 g / 10 min.

[0019] (2) The surface hardness (Shore-A hardness, instantaneous value) measured in accordance with JIS K7215 is 60 to 100.

[0020] (3) The tensile elongation measured in accordance with JIS K6251 is 100% or more.

[0021] [6] The hydrogenated block copolymer (C) The thermoplastic elastomer composition according to any one of [1] to [5], comprising a hydrogenated block copolymer (C1) which is a hydrogenated product of a block copolymer having at least one block (c11) containing the conjugated diene monomer unit as a main component and further containing a vinyl aromatic monomer unit, and at least one block (c2) containing a vinyl aromatic monomer unit as a main component.

[0022] [7] [6] The thermoplastic elastomer composition according to [6], wherein the content of the hydrogenated block copolymer (C1) relative to 100 parts by mass of the polypropylene resin (A) is 50 parts by mass or more and less than 80 parts by mass.

[0023] [8] An injection-molded article comprising the thermoplastic elastomer composition according to any one of [1] to [7].

[0024] [9] [8] A film or sheet made of the injection-molded article according to [8].

[0025]

[10] [8] An automotive interior material comprising the injection-molded article according to the present invention. [Effects of the Invention]

[0026] According to the present invention, it is possible to provide an olefin-based thermoplastic elastomer and a molded article thereof which have improved fogging properties while maintaining a certain level of moldability. DETAILED DESCRIPTION OF THE INVENTION

[0027] Specific embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention.

[0028] In this specification, the expression "polymer" is used to encompass homopolymers and copolymers unless otherwise specified.

[0029] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0030] Furthermore, in this specification, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, it means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0031] [Thermoplastic elastomer composition] The thermoplastic elastomer composition according to the present invention contains the following components (A) to (E), which are at least partially crosslinked: (A) 100 parts by mass of polypropylene resin; (B) 40 to 80 parts by mass of an ethylene-α-olefin copolymer containing ethylene units and α-olefin units having 3 to 20 carbon atoms; (C) 80 to 200 parts by mass of a hydrogenated block copolymer which is a hydrogenated product of a block copolymer having at least one block (c1) mainly composed of conjugated diene monomer units and at least one block (c2) mainly composed of vinyl aromatic monomer units; (D) 100 to 250 parts by mass of a softener, in which the proportion (R) of components having a relative molecular weight of 600 or less in terms of polystyrene, as measured by gel permeation chromatography (GPC), is 29% or less; (E) Polyorganosiloxane: 5 to 20 parts by mass.

[0032] The thermoplastic elastomer composition according to the present invention will be described in detail below.

[0033] <Polypropylene resin (A)> The polypropylene-based resin (A) used in the present invention is a propylene homopolymer or a copolymer of propylene and an olefin other than propylene. In the present invention, the polypropylene-based resin (A) is preferably a polypropylene-based resin selected from at least one of a propylene homopolymer, a random copolymer of propylene and an α-olefin other than propylene, and a block copolymer of propylene and an α-olefin other than propylene.

[0034] The polypropylene resin (A) has a kinematic viscosity of 500,000 mm at 40°C. 2 It is preferable that the speed exceeds 500,000 mm / s. 2 / s" is a concept that includes cases where the fluidity is so low that the kinematic viscosity cannot be measured.

[0035] Suitable raw material olefins other than propylene for the polypropylene resin (A) include α-olefins preferably having 2 or 4 to 20 carbon atoms, specifically ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene. The polymerization mode may be random or block, as long as a resinous product is obtained. These polypropylene resins may be used alone or in combination of two or more.

[0036] The polypropylene resin (A) used in the present invention is preferably a propylene polymer having a propylene content of 40 mol % or more, more preferably a propylene polymer having a propylene content of 50 mol % or more.

[0037] Among these polypropylene-based resins, propylene homopolymers, propylene-ethylene block copolymers, propylene-ethylene random copolymers, propylene-ethylene-butene random copolymers, etc. are particularly preferred.

[0038] The polypropylene resin (A) used in the present invention has a melting point in the range of 80 to 170°C, preferably 120 to 170°C.

[0039] The polypropylene resin (A) used in the present invention preferably has an MFR (ASTM D1238-65T, 230° C., 2.16 kg load) in the range of usually 0.01 to 100 g / 10 min, particularly 0.05 to 50 g / 10 min.

[0040] The polypropylene resin (A) used in the present invention preferably has an isotactic structure as a three-dimensional structure, but it may also have a syndiotactic structure, a mixture of these structures, or a partial atactic structure.

[0041] The polypropylene resin (A) used in the present invention is polymerized by various known polymerization methods.

[0042] <Ethylene-α-olefin copolymer (B)> The ethylene-α-olefin copolymer (B) used in the present invention contains ethylene units and α-olefin units having 3 to 20 carbon atoms. The ethylene-α-olefin copolymer (B) can be obtained, for example, by copolymerizing ethylene with an α-olefin having 3 to 20 carbon atoms.

[0043] The copolymer (B) has a kinematic viscosity of 500,000 mm at 40°C. 2 It is preferable that the speed exceeds 500,000 mm / s. 2 / s" is a concept that includes cases where the fluidity is so low that the kinematic viscosity cannot be measured.

[0044] Specific examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, etc. Among these, from the viewpoint of economic efficiency, α-olefins having 3 to 12 carbon atoms are preferred, and propylene, 1-butene, and 1-octene are particularly more preferred.

[0045] The ethylene-α-olefin copolymer (B) may further contain a monomer unit having an unsaturated bond, if necessary. While there are no particular limitations on such a monomer, from the viewpoint of economic efficiency, preferred are 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, with ethylidene norbornene (ENB) and dicyclopentadiene (DCP) being more preferred.

[0046] The Mooney viscosity (ML) of the ethylene-α-olefin copolymer (B) measured at 100°C is not particularly limited, but from the viewpoint of dispersibility in the thermoplastic elastomer composition of this embodiment, it is preferably 20 to 150, more preferably 50 to 120. The Mooney viscosity (ML) of the ethylene-α-olefin copolymer (B) is measured in accordance with ASTM D1646.

[0047] The ethylene-α-olefin copolymer (B) is preferably produced using a metallocene catalyst. There are no particular limitations on the metallocene catalyst, and examples include those consisting of a cyclopentadienyl derivative of a Group IV metal such as titanium or zirconium and a cocatalyst. Metallocene catalysts are not only highly active as polymerization catalysts, but also produce polymers with narrower molecular weight distributions than Ziegler catalysts, etc., and can achieve a more uniform distribution of the α-olefin monomers with 3 to 20 carbon atoms, which serve as comonomers in the copolymer.

[0048] The copolymerization ratio of the α-olefin in the ethylene-α-olefin copolymer (B) is not particularly limited, but is preferably 1 to 60 mass%, more preferably 10 to 50 mass%, and even more preferably 20 to 45 mass%. By setting the copolymerization ratio of the α-olefin within the above range, the mechanical strength such as tensile strength and flexibility of the molded article can be further improved.

[0049] The density of the ethylene-α-olefin copolymer (B) is not particularly limited, but is preferably 0.80 to 0.90 g / cm 3 It is preferable that the density is 0.85 to 0.89 g / cm 3 By setting the density of the ethylene-α-olefin copolymer (B) within the above range, the flexibility of the molded article is further improved.

[0050] The ethylene-α-olefin copolymer (B) preferably has long chain branches. Here, "long chain branches" refers to branches having 3 or more carbon atoms. The presence of long chain branches enables the production of molded articles with high strength and low density. The ethylene-α-olefin copolymer having long chain branches is not particularly limited, and known copolymers can be used, such as those described in U.S. Pat. No. 5,278,272.

[0051] The ethylene-α-olefin copolymer (B) preferably has a melting point peak in differential scanning calorimetry (DSC) in a temperature range above room temperature. When the ethylene-α-olefin copolymer (B) has a melting point peak in a temperature range above room temperature, it is possible to obtain a molded product that has excellent shape stability and handleability in the temperature range below the melting point and is less sticky.

[0052] The MFR (190°C, 2.16 kg load; according to ASTM D1238) of the ethylene-α-olefin copolymer (B) is not particularly limited, but is preferably 0.01 to 100 g / 10 min, more preferably 0.2 to 10 g / 10 min. By setting the MFR within the above range, a molded product having an excellent balance between molding flowability and mechanical strength can be obtained.

[0053] The content of the ethylene-α-olefin copolymer (B) is 40 to 80 parts by mass, preferably 50 to 70 parts by mass, per 100 parts by mass of the polypropylene resin (A) in terms of the balance between molding flowability and flexibility.

[0054] <Hydrogenated Block Copolymer (C)> The hydrogenated block copolymer (C) used in the present invention is a hydrogenated product of a block copolymer having at least one block (c1) (sometimes referred to herein as "block (c1)") mainly composed of conjugated diene monomer units and at least one block (c2) (sometimes referred to herein as "block (c2)") mainly composed of vinyl aromatic monomer units. Here, "vinyl aromatic monomer unit" refers to a structural unit of a polymer resulting from the polymerization of a vinyl aromatic compound monomer, and has a molecular structure in which two carbon atoms of a substituted ethylene group derived from a substituted vinyl group serve as bonding sites. Furthermore, "conjugated diene monomer unit" refers to a structural unit of a polymer resulting from the polymerization of a conjugated diene monomer, and has a molecular structure in which two carbon atoms of an olefin derived from the conjugated diene monomer serve as bonding sites. In the context of a block copolymer, "mainly composed of" means that the copolymer block contains 50% by mass or more, preferably 60% by mass or more, and more preferably 80% by mass or more of monomer units derived from a conjugated diene monomer (or a vinyl aromatic monomer). For example, a block mainly composed of conjugated diene monomer units means that the block contains 50% by mass or more, preferably 60% by mass or more, and more preferably 80% by mass or more of monomer units derived from a conjugated diene monomer. Similarly, a block mainly composed of vinyl aromatic monomer units means that the block contains 50% by mass or more, preferably 60% by mass or more, and more preferably 80% by mass or more of monomer units derived from a vinyl aromatic monomer.

[0055] Here, examples of the block (c1) mainly composed of conjugated diene monomer units include a polymer block (c10) composed of conjugated diene monomer units (sometimes referred to as "polymer block (c10)" in this specification), and a copolymer block (c11) mainly composed of conjugated diene monomer units and further containing vinyl aromatic monomer units (sometimes referred to as "copolymer block (c11)" in this specification).

[0056] Furthermore, examples of the block (c2) mainly composed of vinyl aromatic monomer units (hereinafter, sometimes referred to as "block (c2)") include a homopolymer block (c20) composed only of vinyl aromatic monomer units, and a copolymer block (c21) mainly composed of vinyl aromatic monomer units and further containing conjugated diene monomer units.

[0057] In the present embodiment, 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.

[0058] In this embodiment, the conjugated diene monomer is a diolefin having one 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, and 1,3-hexadiene. Among these, butadiene and isoprene are preferred from the viewpoint of economic efficiency. These may be used alone or in combination of two or more.

[0059] The arrangement of each block in the hydrogenated product of the block copolymer of this embodiment is not particularly limited, and any suitable arrangement may be adopted. For example, when a polymer block consisting of a vinyl aromatic monomer unit is represented by S and a polymer block consisting of a conjugated diene monomer unit and / or a partially hydrogenated unit thereof is represented by B, the hydrogenated product of this block copolymer has the arrangement of 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), or a linear block copolymer represented by (SB) n3Examples of suitable copolymers include copolymers represented by X (where n3 represents an integer of 3 to 6, and X represents a residue of a coupling agent such as silicon tetrachloride, tin tetrachloride, or a polyepoxy compound). Among these, preferred are linear block copolymers of SB type 2 (diblock), SBS type 3 (triblock), and SBSB type 4 (tetrablock).

[0060] The content of vinyl aromatic monomer units in the hydrogenated block copolymer (C) is 30 to 80% by mass, and from the viewpoint of heat resistance and dispersibility, it is preferably 40 to 80% by mass, and more preferably 50 to 70% by mass. By making the content of vinyl aromatic monomer units 30% by mass or more, mechanical properties can be further improved, and by making it 80% by mass or less, low-temperature properties can be further improved. The content of vinyl aromatic monomer units in the hydrogenated block copolymer (C) can be measured by nuclear magnetic resonance spectroscopy (NMR).

[0061] From the viewpoint of mechanical strength, the content of the vinyl aromatic monomer unit block in the hydrogenated block copolymer (C) is preferably 10% by mass or more, more preferably 10 to 40% by mass. Here, the content of the vinyl aromatic compound polymer block in the hydrogenated block copolymer (C) is defined by the following formula using the mass of the vinyl aromatic compound polymer block (excluding vinyl aromatic compound polymers having an average degree of polymerization of about 30 or less) obtained by a method of 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"):

[0062] Content of vinyl aromatic compound polymer block (mass%)=(mass of vinyl aromatic compound polymer block in copolymer before hydrogenation / mass of copolymer before hydrogenation)×100 When the hydrogenated block copolymer (C) contains a plurality of polymer blocks, the molecular weights, compositions, and other structures of the polymer blocks may be the same or different. For example, the hydrogenated block copolymer (C) may contain a hydrogenated copolymer block containing conjugated diene monomer units and vinyl aromatic monomer units, and a hydrogenated copolymer block mainly composed of conjugated diene monomer units. The boundaries and ends of the blocks do not necessarily need to be clearly distinguished. The distribution of the vinyl aromatic monomer units in each polymer block is not particularly limited, and may be uniform, tapered, stepped, convex, or concave. Furthermore, crystalline portions may be present in the polymer blocks.

[0063] The distribution of vinyl units in the conjugated diene monomer units in each polymer block is not particularly limited, and for example, the distribution may be biased. Methods for controlling the distribution of vinyl units include adding a vinylating agent during polymerization and changing the polymerization temperature. Furthermore, the distribution of hydrogenation rates of the conjugated diene monomer units may be biased. The hydrogenation rate distribution can be controlled by changing the distribution of vinyl units, or by copolymerizing isoprene and butadiene and then hydrogenating them using a hydrogenation catalyst described below, thereby utilizing the difference in hydrogenation rate between the isoprene unit and the butadiene unit.

[0064] In the hydrogenated block copolymer (C), from the viewpoints of heat resistance, aging resistance, and weather resistance, preferably 75 mol % or more, more preferably 85 mol % or more, and even more preferably 97 mol % or more of the unsaturated bonds contained in the conjugated diene monomer units before hydrogenation are hydrogenated.

[0065] The hydrogenation catalyst used for hydrogenation is not particularly limited, and examples of the conventionally known homogeneous hydrogenation catalysts that can be used include (1) supported heterogeneous hydrogenation catalysts in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, or diatomaceous earth, (2) so-called Ziegler-type hydrogenation catalysts that use a transition metal salt such as an organic acid salt or an acetylacetone salt of Ni, Co, Fe, or Cr, etc., and a reducing agent such as an organoaluminum, and (3) so-called organometallic complexes of organometallic compounds such as Ti, Ru, Rh, or Zr. Specific examples of the hydrogenation catalysts that can be used include the hydrogenation catalysts described in JP-B Nos. 42-008704, 43-006636, 63-004841, 01-037970, 01-053851, and 02-009041. Among these, preferred hydrogenation catalysts include reducing organometallic compounds such as titanocene compounds.

[0066] As the titanocene compound, for example, compounds described in JP-A-08-109219 can be used, and specific examples include compounds having at least one ligand having a (substituted) cyclopentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton, such as biscyclopentadienyltitanium dichloride and monopentamethylcyclopentadienyltitanium trichloride.

[0067] Examples of the reducing organometallic compound include organic alkali metal compounds such as organolithium compounds, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.

[0068] In this embodiment, the polymerization method for the hydrogenated block copolymer (C) before hydrogenation is not particularly limited, and known methods can be used, such as those described in JP-B Nos. 36-019286, 43-017979, 46-032415, 49-036957, 48-002423, 48-004106, 56-028925, JP-A Nos. 59-166518, and 60-186577.

[0069] If necessary, the hydrogenated block copolymer (C) 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 sulfonate 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 alkoxy silicon group, a tin halide group, a boronic acid group, a boron-containing group, a boronate salt group, an alkoxy tin group, and a phenyl tin group.

[0070] The vinyl bond content in the conjugated diene monomer units of the pre-hydrogenated copolymer in the hydrogenated block copolymer (C) is preferably 5 mol% or more from the viewpoints of flexibility and scratch resistance, and is 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 units is more preferably 10 to 50 mol%, even more preferably 10 to 30 mol%, and even more preferably 10 to 25 mol%.

[0071] The vinyl bond content herein means the proportion of 1,2-bonds and 3,4-bonds among the 1,2-bonds, 3,4-bonds and 1,4-bonds incorporated in the conjugated diene before hydrogenation. The vinyl bond content can be measured by NMR.

[0072] The weight-average molecular weight of the hydrogenated block copolymer (C) before crosslinking is not particularly limited, but is preferably 50,000 or more from the viewpoint of scratch resistance, and preferably 400,000 or less from the viewpoint of molding flowability, and 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 is preferably close to 1 from the viewpoint of scratch resistance. The weight-average molecular weight and number-average molecular weight can be determined by gel permeation chromatography (GPC; Shimadzu Corporation, instrument name "LC-10") using tetrahydrofuran (1.0 mL / min) as a solvent at an oven temperature of 40°C, using TSKgel GMHXL columns (4.6 mm ID x 30 cm, two columns). The weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) are calculated as polystyrene-equivalent molecular weights.

[0073] The blending amount of the hydrogenated block copolymer (C) is 80 to 200 parts by mass, and preferably 90 to 170 parts by mass, relative to 100 parts by mass of the polypropylene resin (A). If the content of the hydrogenated block copolymer (C) is less than 80 parts by mass, flexibility and scratch resistance may be insufficient, whereas if it exceeds 200 parts by mass, mechanical properties may be poor.

[0074] The hydrogenated block copolymer (C) preferably contains, as the block (c1) mainly composed of conjugated diene monomer units, a hydrogenated block copolymer (C1) having at least one copolymer block (c11) mainly composed of conjugated diene monomer units and further containing vinyl aromatic monomer units, and at least one block (c2) mainly composed of vinyl aromatic monomer units. In this case, the hydrogenated block copolymer (C) may consist solely of the hydrogenated block copolymer (C1), or may further contain, in addition to the hydrogenated block copolymer (C1), a hydrogenated block copolymer (C2) consisting of one or more polymer blocks (c10) composed of conjugated diene monomer units and one or more blocks (c2) mainly composed of vinyl aromatic monomer units.

[0075] The copolymer block (c11) mainly containing conjugated diene monomer units and further containing vinyl aromatic monomer units is not particularly limited, and the above-mentioned conjugated diene monomers and vinyl aromatic monomers 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, and a block containing isoprene units and styrene units.

[0076] The copolymer block (c11) may contain at least conjugated diene monomer units as a main component, 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 vinyl aromatic monomer units in the copolymer block (c11) 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.

[0077] The conjugated diene monomers described above can be used as the conjugated diene monomer constituting the polymer block (c10) consisting of conjugated diene monomer units. Such a polymer block (c10) is typically a homopolymer block consisting only of conjugated diene monomer units, and preferred examples thereof include a homopolymer block consisting only of butadiene units and a homopolymer block consisting only of isoprene units. However, the polymer block (c10) does not necessarily exclude the presence of monomer units other than the conjugated diene monomer units, so long as it can exhibit the same effects as a homopolymer block consisting only of conjugated diene monomer units. For example, it may contain a trace amount of vinyl aromatic monomer units that may be inevitably mixed in during the production process.

[0078] On the other hand, the block (c2) mainly composed of vinyl aromatic monomer units may be, as described above, a homopolymer block (c20) composed only of vinyl aromatic monomer units, or may be a copolymer block (c21) mainly containing vinyl aromatic monomer units and further containing conjugated diene monomer units, and is preferably a homopolymer block (c20) composed only of vinyl aromatic monomer units.

[0079] Here, the hydrogenated block copolymer (C1) can be obtained from the vinyl aromatic monomer and the conjugated diene monomer by the above-mentioned method. For example, (Step A1) forming a block (c2) mainly composed of vinyl aromatic monomer units from a vinyl aromatic monomer; (Step A2) copolymerizing the block (c2) obtained in Step A1 with a conjugated diene monomer and a vinyl aromatic monomer; A block copolymer is obtained by a process comprising the steps of: (Step A3) A step of reacting the block copolymer with hydrogen in the presence of the hydrogenation catalyst It can be obtained by performing the following.

[0080] On the other hand, the hydrogenated block copolymer (C2) can also be obtained from the vinyl aromatic monomer and the conjugated diene monomer by the method described above. For example, (Step B1) forming a block (c2) mainly composed of vinyl aromatic monomer units from a vinyl aromatic monomer; (Step B2) The above step B1 a step of polymerizing a conjugated diene monomer with respect to the block (c2) obtained in the step (a); A block copolymer is obtained by the process comprising: (Step B3) A step of reacting the block copolymer with hydrogen in the presence of the hydrogenation catalyst It can be obtained by performing the following.

[0081] The hydrogenated block copolymer (C) preferably comprises a combination of at least two hydrogenated block copolymers: (C-1) a hydrogenated block copolymer having a vinyl aromatic monomer unit block content of 20% to less than 50% by mass, and (C-2) a hydrogenated block copolymer having a vinyl aromatic monomer unit block content of 50% to 80% by mass. The (C-1) component with a low vinyl aromatic monomer unit content contributes to the low-temperature properties of the thermoplastic elastomer composition, while the (C-2) component with a high vinyl aromatic monomer unit content contributes to stabilizing the matrix and domain morphology of the thermoplastic elastomer composition. The mass ratio (C-1 / C-2) of the (C-1) component to the (C-2) component is preferably 90 / 10 to 60 / 40 from the viewpoints of low-temperature properties and mechanical properties. For example, when the hydrogenated block copolymer (C) contains two or more hydrogenated block copolymers (C2), it is preferable that one or more of the hydrogenated block copolymers (C2) constitute the component (C-1), and one or more of the hydrogenated block copolymers (C2) constitute the component (C-2). Also, when the hydrogenated block copolymer (C) contains the hydrogenated block copolymer (C1) and two or more hydrogenated block copolymers (C2), the hydrogenated block copolymer (C1) and one or more of the hydrogenated block copolymers (C2) may constitute the component (C-1), and one or more of the hydrogenated block copolymers (C2) may constitute the component (C-2).

[0082] Furthermore, the content of the hydrogenated block copolymer (C1) relative to 100 parts by mass of the polypropylene resin (A) is preferably 50 parts by mass or more and less than 80 parts by mass, and more preferably 60 to 75 parts by mass.

[0083] <Softener (D)> The softener (D) used in the present invention has a proportion (R) of components having a polystyrene-equivalent relative molecular weight of 600 or less, as measured by gel permeation chromatography (GPC), of 29% or less. Here, the proportion (R) is preferably 27% or less, more preferably 25% or less, and even more preferably 23% or less. When the proportion (R) is a certain amount or less, it is preferable because good fogging properties can be obtained, such as reducing fogging, particularly at high temperatures.

[0084] The softener (D) used in the present invention preferably has a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 100 to 2000, more preferably 300 to 1500, and even more preferably 500 to 1000. The softener (D) used in the present invention preferably has a molecular weight distribution (Mw / Mn) measured by gel permeation chromatography (GPC) of 0.5 to 5.0, more preferably 0.5 to 3.0, and even more preferably 0.5 to 2.0. Having the Mw and Mw / Mn within the above ranges is preferred in terms of obtaining good fogging properties.

[0085] The softener (D) typically has an evaporation loss of 0.3% by mass or less at 200°C and atmospheric pressure for 1 hour, and from the viewpoint of fogging properties, it is preferably 0.2% by mass or less, more preferably 0.15% by mass or less, and even more preferably 0.13% by mass or less. The evaporation loss of 200°C and atmospheric pressure for 3 hours is preferably 1.2% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.8% by mass or less. The evaporation loss of 200°C and atmospheric pressure for 5 hours is preferably 2.5% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less. In this specification, the evaporation loss is sometimes referred to as the "heat evaporation loss."

[0086] Furthermore, in terms of fogging properties, the softener (D) preferably has an amount of fogging compounds (FOG) measured in accordance with VDA278 (sometimes referred to as "FOG value" in this specification) of 1000 μg / g or less, more preferably 500 μg / g or less, and even more preferably 250 μg / g or less.

[0087] The kinematic viscosity of the softener (D) at 40°C is often 500,000 mm 2 / s or less, and from the viewpoint of compatibility with polypropylene resins and moldability, it is preferably 400 mm 2 / s or less, preferably 300 mm 2 / s or less, more preferably 200 mm 2 / s or less. D ) at 40 ° C. is preferably 40 mm 2 / s or more, preferably 50 mm 2 / s or more.

[0088] The softener (D) can be any oil that satisfies the above-mentioned properties, and may be, for example, a refined mineral oil, a synthetic oil obtained by polymerizing an olefin monomer, or a mixture of a refined mineral oil and a synthetic oil. The softener (D) may also be a non-bio-oil obtained from fossil raw materials, or a bio-oil obtained from animal or plant raw materials.

[0089] The refined mineral oil may be any known refined mineral oil, and among these, those containing paraffin as a main component are preferred. The flash point of such refined mineral oils is usually 240°C to 300°C. An example of such a refined mineral oil is disclosed in JP 2000-302919 A. Preferably, the residual oil obtained by atmospheric distillation of paraffin-based crude oil is subjected to a conventional vacuum distillation operation to obtain an effluent oil, which is then dewaxed by solvent extraction or hydrotreating, hydrofinished, and further subjected to vacuum distillation to remove light fractions.

[0090] The synthetic oil is preferably a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms, and may contain a small amount of polyene as needed. The α-olefin used may be one type or two or more types. Among these copolymers, an ethylene-propylene copolymer is particularly preferred. The ethylene content of the synthetic oil used in the present invention is preferably in the range of 50 to 80 mol%, more preferably in the range of 60 to 75 mol%, and particularly preferably in the range of 65 to 75 mol%.

[0091] The synthetic oil used in the present invention may be produced by any known method, but is preferably produced using a metallocene catalyst, which makes it easier to obtain a synthetic oil with a narrow molecular weight distribution and an olefin-based thermoplastic elastomer with excellent fogging properties.

[0092] The blending amount of the softener (D) is 100 to 250 parts by mass, preferably 100 to 150 parts by mass, per 100 parts by mass of the polypropylene resin (A), from the viewpoint of ensuring good flexibility and processability while suppressing oil bleeding.

[0093] <Polyorganosiloxane (E)> The thermoplastic elastomer composition of the present invention contains a polyorganosiloxane (E). The structure of the polyorganosiloxane (E) is not particularly limited, but from the viewpoints of abrasion resistance and feel, it is preferable that the polyorganosiloxane (E) has a linear, branched, or crosslinked polymer structure.

[0094] The polyorganosiloxane used as polyorganosiloxane (E) is not particularly limited, and can be known.Preferred polyorganosiloxane is a polymer containing siloxane units having substituents such as alkyl group, vinyl group, aryl group, etc., and among these, particularly, the polyorganosiloxane having alkyl group is preferred, and the polyorganosiloxane having methyl group is more preferred.

[0095] Specific examples of polyorganosiloxanes having a methyl group include polydimethylsiloxane, polymethylphenylsiloxane, polymethylhydrogensiloxane, etc. Among these, polydimethylsiloxane is preferred.

[0096] The kinematic viscosity of the polyorganosiloxane (E) is not particularly limited, but from the viewpoint of abrasion resistance, the kinematic viscosity (25°C) specified in JIS Z8803 is 5,000 centistokes (cSt) or more (i.e., 5,000 mm 2 In addition, from the viewpoint that the dispersibility of the polyorganosiloxane (E) in the thermoplastic elastomer composition of the present embodiment tends to be improved, the appearance is excellent, and the quality stability during melt extrusion also tends to be further improved, the kinematic viscosity of the polyorganosiloxane (E) is preferably less than 100,000 cSt (i.e., 100,000 mm 2 The kinematic viscosity of the polyorganosiloxane (E) is preferably 10,000 cSt or more and less than 100,000 cSt (i.e., 10,000 mm 2 / s or more 100,000mm 2 / s), and more preferably 50,000 cSt or more but less than 100,000 cSt (i.e., 50,000 mm 2 / s or more 100,000mm 2 / s).

[0097] The amount of polyorganosiloxane (E) to be blended is 5 to 20 parts by mass, preferably 8 to 15 parts by mass, per 100 parts by mass of the polypropylene resin (A), from the viewpoint of suppressing bleeding during molding and ensuring good abrasion resistance.

[0098] <Configuration of Thermoplastic Elastomer Composition> The thermoplastic elastomer composition of the present invention contains the polypropylene resin (A), the ethylene-α-olefin copolymer (B), the hydrogenated block copolymer (C), the softener (D), and the polyorganosiloxane (E), and is at least partially crosslinked.

[0099] The thermoplastic elastomer composition of the present invention preferably satisfies the following requirements (1) to (3): Requirement (1): The thermoplastic elastomer composition of the present invention preferably has a melt flow rate (MFR, 230°C, 1.2 kg load) measured in accordance with ASTM D1238 of 30 to 100 g / 10 min, more preferably 50 to 90 g / 10 min.

[0100] Requirement (2): The thermoplastic elastomer composition of the present invention preferably has a surface hardness (Shore-A hardness, instantaneous value) measured in accordance with JIS K7215 of 60 to 100, more preferably 60 to 80. The surface hardness can be measured by the method described in the examples below.

[0101] Requirement (3): The thermoplastic elastomer composition of the present invention preferably has a tensile elongation of 100% or more, more preferably 200% or more, as measured in accordance with JIS K 6251. The upper limit of the tensile elongation is not particularly limited as long as it does not impair the effects of the present invention, but is, for example, 600%.

[0102] A thermoplastic elastomer composition that satisfies the above requirements (1) to (3) is easy to process by injection molding and other methods, has a good feel to the touch, and has high durability.

[0103] Furthermore, the thermoplastic elastomer composition of the present invention preferably satisfies the following requirement (4) in addition to the requirements (1) to (3): Requirement (4): From the viewpoints of moldability, durability, and touch, the thermoplastic elastomer composition of the present invention preferably has a melt flow rate (MFR, 230°C, 2.16 kg load) measured in accordance with ASTM D1238 of 100 to 350 g / 10 min, more preferably 150 to 300 g / 10 min.

[0104] A thermoplastic elastomer composition that satisfies the above requirements (1) to (3), and desirably satisfies the above requirements (1) to (4), can be produced as follows.

[0105] Regarding the requirements (1) and (4), the MFR of the thermoplastic elastomer composition can be adjusted by changing the amount of organic peroxide added when mixing the thermoplastic elastomer and polypropylene resin as raw materials in an extruder. For example, the MFR of the resulting thermoplastic elastomer composition tends to increase as the amount of organic peroxide added increases.

[0106] Regarding the requirement (2), the surface hardness of the thermoplastic elastomer composition can be adjusted by changing the composition of the thermoplastic elastomer composition. For example, the surface hardness of the resulting thermoplastic elastomer composition tends to increase as the amount of softener added decreases.

[0107] Regarding the requirement (3), the tensile elongation of the thermoplastic elastomer composition can be adjusted by changing the composition of the thermoplastic elastomer composition. For example, the tensile elongation of the resulting thermoplastic elastomer composition tends to increase as the ratio of the hydrogenated block copolymer (C) to the polypropylene resin (A) increases.

[0108] In this way, by appropriately adjusting the amount of organic peroxide and the composition of the thermoplastic elastomer composition, it is possible to obtain a thermoplastic elastomer composition that satisfies the above (1) to (4).

[0109] The thermoplastic elastomer composition of the present invention may consist solely of the polypropylene resin (A), the ethylene-α-olefin copolymer (B), the hydrogenated block copolymer (C), the softener (D), and the polyorganosiloxane (E), as long as they are at least partially crosslinked. However, the thermoplastic elastomer composition of the present invention may contain, in addition to the polypropylene resin (A), the ethylene-α-olefin copolymer (B), the hydrogenated block copolymer (C), the softener (D), and the polyorganosiloxane (E), other components (hereinafter referred to as "other components") that do not fall under the category of the polypropylene resin (A), the ethylene-α-olefin copolymer (B), the hydrogenated block copolymer (C), the softener (D), or the polyorganosiloxane (E).

[0110] Here, the crosslinking is usually carried out in the presence of a crosslinking agent. Therefore, in one preferred embodiment of the present invention, the thermoplastic elastomer composition of the present invention further contains a crosslinking agent described below. In this case, it may further contain a crosslinking aid described below. The crosslinking agent and the crosslinking aid will be explained below in the sections "Crosslinking Agent" and "Crosslinking Aid," respectively.

[0111] The thermoplastic elastomer composition of the present invention may contain, as necessary, components other than the polypropylene resin (A), the ethylene-α-olefin copolymer (B), the hydrogenated block copolymer (C), the softener (D), the polyorganosiloxane (E), the optional crosslinking agent, and the optional crosslinking aid, such as inorganic fillers, plasticizers, and other additives, within the scope of the present invention.

[0112] Examples of inorganic fillers include calcium carbonate, magnesium carbonate, silica, carbon black, glass fiber, titanium oxide, clay, mica, talc, magnesium hydroxide, and aluminum hydroxide.

[0113] Examples of the plasticizer include polyethylene glycol and phthalate esters such as dioctyl phthalate (DOP).

[0114] Other additives include organic and inorganic pigments such as carbon black, titanium oxide, and 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; bis-[2,2,6,6-tetramethyl-4-piperidinyl]sebacate, tetrakis(isopropyl alcohol); Examples of suitable anti-bacterial agents include light stabilizers such as (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 palmitic acid monoglyceride and stearic acid monoglyceride; and antibacterial agents such as silver ion-supported zeolite and silver thiosulfite complex.

[0115] Crosslinking agent The thermoplastic elastomer composition of the present invention may further contain a crosslinking agent in addition to the components (A) to (E). Examples of such crosslinking agents include commonly used crosslinking agents such as organic peroxides, phenolic resins, sulfur, hydrosilicone compounds, amino resins, quinones or their derivatives, amine compounds, azo compounds, epoxy compounds, isocyanates, and thermosetting elastomers. In the present invention, the crosslinking agent is preferably an organic peroxide. This organic peroxide acts as a crosslinking initiator for the ethylene-α-olefin copolymer (B) and the polyorganosiloxane (E) during crosslinking and also promotes the decomposition reaction of the polypropylene resin (A). As a result, the flowability and moldability of the thermoplastic elastomer composition can be further improved. Even when manufacturing parts with large surface areas and complex shapes, the composition conforms well to molds and can fill the mold more completely without gaps.

[0116] Specific examples of the organic peroxide include 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 Peroxyketals such as (t-butylperoxy)valerate; 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, and other dialkyl peroxides; acetyl peroxide, isobutyryl peroxide diacyl peroxides such as octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and m-trioyl peroxide; t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate, and di-t-butyl peroxide peroxyesters such as t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, and cumylperoxyoctate; and hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, and 1,1,3,3-tetramethylbutyl peroxide.

[0117] Among the above compounds, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3 are preferred from the viewpoints of thermal decomposition temperature, crosslinking performance, etc. In one preferred embodiment of the present invention, the crosslinking agent is 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane.

[0118] The amount of such organic peroxide is preferably 2 to 6 parts by mass, more preferably 2 to 4 parts by mass, based on 100 parts by mass of the polypropylene resin (A) from the viewpoint of molding flowability.

[0119] Crosslinking aid In the present invention, a crosslinking aid can be blended in the crosslinking treatment using the organic peroxide. That is, when the thermoplastic elastomer composition of the present invention contains the organic peroxide as the crosslinking agent, the thermoplastic elastomer composition may further contain a crosslinking aid. The crosslinking aid that can be used in the present invention is preferably a monofunctional monomer or a polyfunctional monomer, since it can control the crosslinking reaction rate.

[0120] As the monofunctional monomer, for example, a radically polymerizable vinyl monomer is preferable, and examples thereof include an aromatic vinyl monomer, an unsaturated nitrile monomer such as acrylonitrile or methacrylonitrile, an acrylic acid ester monomer, a methacrylic acid ester monomer, an acrylic acid monomer, a methacrylic acid monomer, a maleic anhydride monomer, and an N-substituted maleimide monomer.

[0121] 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 viewpoints of reactivity and versatility. These monofunctional monomers may be used alone or in combination of two or more.

[0122] The polyfunctional monomer is a monomer having a plurality of radically polymerizable functional groups as functional groups, and is preferably a monomer having a vinyl group. The number of functional groups in the polyfunctional monomer is preferably two or three.

[0123] Specific examples of polyfunctional 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, diisopropenylbenzene, p-quinone dioxime, p,p'-dibenzoylquinone dioxime, phenylmaleimide, allyl methacrylate, N,N'-m-phenylene bismaleimide, diallyl phthalate, tetraallyloxyethane, and 1,2-polybutadiene, with divinylbenzene and triallyl isocyanurate being more preferred. These polyfunctional monomers may be used alone or in combination of two or more.

[0124] The crosslinking aid as described above is preferably used in an amount of 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass, per 100 parts by mass of the polypropylene resin (A) from the viewpoint of molding flowability.

[0125] <Method of producing thermoplastic elastomer composition> The thermoplastic elastomer composition of the present invention can be obtained by crosslinking a mixture containing the polypropylene resin (A), the ethylene-α-olefin copolymer (B), the hydrogenated block copolymer (C), the softener (D), and the polyorganosiloxane (E). The method for crosslinking is not particularly limited and may be a known method. The crosslinking is preferably carried out in the presence of the crosslinking agent. The conditions for the crosslinking reaction are not particularly limited, and suitable conditions can be selected as appropriate depending on the desired physical properties of the thermoplastic elastomer composition of the present embodiment.

[0126] The thermoplastic elastomer composition of this embodiment can be produced using a common method, such as a Banbury mixer, kneader, single-screw extruder, or twin-screw extruder, which are used in the production of conventional elastomer compositions. Among these, a twin-screw extruder is preferred from the viewpoint of efficiently achieving dynamic crosslinking of the thermoplastic elastomer. When using a twin-screw extruder, for example, the polypropylene resin (A), the polyorganosiloxane (E), the crosslinking agent, etc. can be added and uniformly and finely dispersed, and then other components can be further added to cause a crosslinking reaction of the composition, thereby allowing the thermoplastic elastomer composition to be produced continuously, making it more suitable.

[0127] The thermoplastic elastomer composition may also be produced via the following processing steps. Specifically, the polypropylene resin (A), the ethylene-α-olefin copolymer (B), and the polyorganosiloxane (E) are thoroughly mixed and then charged into the hopper of an extruder. In this case, the crosslinking agent may be added to the extruder together with the polypropylene resin (A), the ethylene-α-olefin copolymer (B), and the polyorganosiloxane (E) from the beginning, or a portion of the crosslinking agent may be added midway through the extruder. Furthermore, a portion of the polypropylene resin (A), the ethylene-α-olefin copolymer (B), and the polyorganosiloxane (E) may also be added midway through the extruder. The hydrogenated block copolymer (C) may also be added midway through the extruder, or it may be added separately at the beginning and midway through the extruder. In this case, the crosslinking agent and the hydrogenated block copolymer (C) may also be premixed and then added. The softener (D) can also be added from the beginning, added in portions at the beginning and during the process, or added only during the process. The method for adding the softener (D) may be a method of adding a masterbatch containing the softener (D) at a high concentration in advance using any thermoplastic resin or elastomer.

[0128] In either case, the addition results in a mixture containing the polypropylene resin (A), the ethylene-α-olefin copolymer (B), the hydrogenated block copolymer (C), the softener (D), and the polyorganosiloxane (E).

[0129] Next, the mixture is kneaded in the presence of the crosslinking agent and the like. In a preferred and typical embodiment of the present invention, the kneading is carried out in a molten state under heating in an extruder. When heated, melted, and kneaded in the extruder, the ethylene-α-olefin copolymer (B) and the polyorganosiloxane (E) undergo a crosslinking reaction with the crosslinking agent, and at the same time, the crosslinking agent promotes the decomposition reaction of the polypropylene resin (A), thereby improving molding fluidity. Furthermore, the hydrogenated block copolymer (C) and the like are added and melt-kneaded. After sufficient crosslinking reaction, kneading, and dispersion, pellets of the thermoplastic elastomer composition can be obtained by removing the mixture from the extruder.

[0130] During this kneading process, the mixture may be crosslinked by dynamic crosslinking. Specifically, the dynamic crosslinking is carried out by kneading the mixture in a molten state in the presence of a crosslinking agent, and applying shear force to the mixture to crosslink and decompose the polypropylene resin (A), the ethylene-α-olefin copolymer (B), the hydrogenated block copolymer (C), and the polyorganosiloxane (E). A thermoplastic elastomer composition can also be obtained by dynamic crosslinking. This dynamic crosslinking is preferably carried out using a twin-screw extruder.

[0131] [Molded body] The molded article according to the present invention includes the thermoplastic elastomer composition. The molded article may be in the form of a film or a sheet. Examples of uses of the molded article include automotive interior materials.

[0132] Such a molded article according to the present invention can be obtained by molding the thermoplastic elastomer composition using various molding methods. Examples of such molding methods include injection molding, extrusion molding, vacuum molding, pressure molding, blow molding, calendar molding, and foam molding. For example, a molded article such as a skin material can be obtained by filling a mold with the thermoplastic elastomer composition melted by heating, solidifying it, and then demolding it.

[0133] The thermoplastic elastomer composition of the present embodiment is preferably formed into an injection-molded article (injection-molded product). When formed into an injection-molded article, productivity is excellent. The shape of the injection-molded article is not particularly limited, but from the viewpoint of use as a skin material, it is preferably a film or sheet.

[0134] The injection-molded article can be used for various components, but is particularly preferred for use as an instrument panel or other automotive interior material, from the viewpoint that thin-walled molded articles with complex shapes can be injection-molded with good reproducibility. Among automotive interior materials, instrument panels typically have complex shapes that are not only thin and have a large surface area, but also have a grain pattern on the surface, partial openings, flat and curved portions, three-dimensional structures, and thick and thin portions. According to this embodiment, an injection-molded article with a thin wall and a large surface area can be obtained, making it suitable for use as an instrument panel or a component thereof.

[0135] The shape and configuration of the automotive interior material are not particularly limited, and can be appropriately selected depending on the application, etc. One preferred example is a laminate comprising a layer containing the automotive interior material of this embodiment (hereinafter sometimes referred to as a "skin material layer") and a layer containing a core material (hereinafter sometimes referred to as a "core material layer") laminated on the layer containing the automotive interior material. By using a laminate that combines not only a skin material layer but also a core material layer, even complex three-dimensional shapes can be mass-produced stably, thereby improving production efficiency and reducing costs.

[0136] The core material is not particularly limited and may be any known material, such as polypropylene, acrylonitrile-butadiene-styrene (ABS) resin, polycarbonate / acrylonitrile-butadiene-styrene alloy (PC / ABS alloy), acrylonitrile-styrene copolymer, modified polyphenylene oxide, or resins containing fillers such as talc or glass fiber mixed into them as needed to improve strength. Among these, preferred are those containing at least one selected from the group consisting of polypropylene, acrylonitrile-butadiene-styrene (ABS) resin, polycarbonate / acrylonitrile-butadiene-styrene alloy (PC / ABS alloy), and polyphenylene ether. Furthermore, polypropylene is more preferred from the standpoint of lightweight properties.

[0137] The layer structure of the laminate of this embodiment is not particularly limited, and may be a two-layer or more structure including at least a skin layer and a core layer. In this embodiment, the skin layer and the core layer do not necessarily need to be in contact with each other, and another layer may be present between the skin layer and the core layer.

[0138] The thickness of the skin layer is not particularly limited, but is preferably 0.5 to 2.0 mm, and more preferably 0.8 to 1.5 mm. A skin layer thickness of 0.5 mm or more can provide better appearance, chemical resistance, and abrasion resistance, while a skin layer thickness of 2.0 mm or less can provide better cost performance and tactile feel. While it has been difficult to efficiently produce such a thin skin layer using conventional techniques, the use of the thermoplastic elastomer composition of the present embodiment makes it possible to easily produce such a thin skin layer.

[0139] The thickness of the core layer is not particularly limited, but is preferably 2.0 to 4.5 mm, and more preferably 2.5 to 3.5 mm. By making the core layer thickness 2.0 mm or more, it is possible to achieve even better rigidity, heat resistance, and moldability, and by making it 4.5 mm or less, it is possible to achieve even better economy and lightness.

[0140] Furthermore, the laminate of the present embodiment preferably further comprises a layer containing a foam material between the skin layer and the core layer, and the foam material has a density of 100 to 250 kg / m 3 It is more preferable that the foam contains a thermosetting urethane foam having a density of 100 kg / m 3 By setting the density of the foam material at 250 kg / m or more, it is possible to make it difficult for indentations to be made during handling during production or removal, and to improve handling properties. 3 By setting the density of the foam material to 120 to 180 kg / m or less, it is possible to impart appropriate flexibility to the laminate. 3 It is more preferable that:

[0141] The type of thermosetting urethane foam is not particularly limited, but semi-rigid thermosetting urethane foam is preferred. Semi-rigid thermosetting urethane foam refers to urethane foam with an open cell structure of 90% or more.

[0142] The method for producing the laminate is not particularly limited, and known methods can be used, such as a method in which the skin material, core material, and foam material are molded separately, and then these members are laminated using a chloroprene-based adhesive or the like to form a layer structure, or a method in which the core material is molded in advance, and then the core material is placed in a mold and molded integrally with the molding of the skin material (integral molding), and the core material and the two members are laminated to form a layer structure.

[0143] The above-mentioned layer structure makes it possible to obtain a laminate having a uniform thickness, good grain reproducibility, and a skin material with a good feel and appearance, while also enabling stable mass production of even complex three-dimensional shapes. Furthermore, by using a layer structure of three or more layers including the above-mentioned foam material, it is possible to obtain a laminate that further utilizes the soft feel of the skin material.

[0144] The laminate can be suitably used as an automotive interior material, particularly for thin-walled, large-surface-area instrument panels, door panels, glove box lids, and the like, which have been difficult to produce by injection molding in the past, and is particularly suitable for instrument panels.

[0145] The instrument panel of this embodiment provides the same effects as those described in the embodiments of the automotive skin material and laminate. Furthermore, the skin material has good elongation properties at low temperatures, making it easier to ensure the low-temperature deployment performance of the passenger airbag. It also makes it possible to maintain and improve design freedom, for example, by making the skin material seamless in the airbag installation area. [Example]

[0146] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, various physical properties were measured as follows.

[0147] [Measurement method] (1) Melt flow rate (MFR) The melt flow rate (MFR) was measured in accordance with ASTM D1238 under conditions of a heating temperature of 230°C and a load of 1.2 kg. If necessary, the measurement was also performed under conditions of a heating temperature of 230°C and a load of 2.16 kg.

[0148] (2) Surface hardness (Shore-A hardness) The surface hardness was measured as Shore-A hardness (also called "JIS-A hardness"). Here, the Shore-A hardness was measured by stacking four 2 mm thick sheets as samples and evaluating them in an A type atmosphere at 23°C in accordance with JIS K7215. The hardness at the moment when the probe of the hardness tester was lowered onto the sample (instantaneous value) and the hardness 10 seconds after the probe was lowered were measured as surface hardness (after 10 seconds).

[0149] (3) Mechanical properties (tensile strength and tensile elongation) According to JIS K6251, the tensile strength (MPa) and tensile elongation (%) were evaluated in an atmosphere of 23°C.

[0150] (4) Fogging The fogging property was measured in accordance with VDA278 by integrating peaks detected higher than the baseline and calculating the FOG value (μg / g).

[0151] (5) Physical properties of hydrogenated block copolymer (C) and the corresponding unhydrogenated copolymer (5-1) Hydrogenation rate The hydrogenation rate of the hydrogenated block copolymer (C) was measured by nuclear magnetic resonance spectroscopy (NMR). A nuclear magnetic resonance spectrometer (JEOL, model 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. Measurements were performed under the following conditions: sample concentration 50 mg / mL, observation frequency 400 MHz, pulse delay 2.904 seconds, scan count 64, pulse width 45°C, and measurement temperature 26°C.

[0152] (5-2) Content of Monomer Units and Bonding Units The contents of vinyl aromatic monomer units, ethylene monomer units, butylene monomer units, and 1,4-bond units, 1,2-bond units, and 3,4-bond units of butadiene contained in the hydrogenated block copolymer (C) and the corresponding unhydrogenated copolymer were measured by NMR. A nuclear magnetic resonance spectrometer (JEOL, model 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. Measurements were performed under the following conditions: sample concentration 50 mg / mL, observation frequency 400 MHz, pulse delay 2.904 seconds, scan count 64, pulse width 45°C, and measurement temperature 26°C.

[0153] The mass fraction (mass%) of each structural unit contained in the ethylene-α-olefin copolymer (B) is 13Specifically, the C-NMR of copolymer (A-1) was measured using an ECX400P nuclear magnetic resonance spectrometer (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 accumulation number of 8000. 13 Calculated from the C-NMR spectrum.

[0154] (5-3) Styrene polymer block content (Os value) The styrene polymer block content was measured using the corresponding unhydrogenated copolymer by the method described in I.M. Kolthoff, et al., J. Polym. Sci. 1, 429 (1946) (osmium tetroxide decomposition method). A 0.1 g / 125 mL tertiary butanol solution of osmic acid was used to decompose the unhydrogenated copolymer. The styrene polymer block content was calculated using the following formula. The styrene polymer block content obtained here is referred to as the "Os value."

[0155] Styrene polymer block content (Os value; mass%) = [(mass of the styrene polymer block in the copolymer before hydrogenation) / (mass of the copolymer before hydrogenation)] × 100 (5-4) Molecular weight distribution The hydrogenated block copolymer (C) was subjected to gel permeation chromatography (GPC) measurement under the following conditions to determine the polystyrene-equivalent weight average molecular weight Mw, number average molecular weight Mn, and Mw / Mn.

[0156] Measuring model: Shimadzu Corporation Made , LC-10 Column: TSKgel GMHXL (4.6 mm ID x 30 cm) x 2 Solvent: tetrahydrofuran Temperature: Oven temperature 40℃ Concentration: 0.1% Flow rate: 1.0mL / min Detector: Differential refractometer (RI) Column calibration: Monodisperse polystyrene (Tosoh Corporation); #3 standard set Molecular weight conversion: Polystyrene conversion / standard conversion method (5-5) Loss tangent (tanδ peak temperature) The loss tangent (tan δ peak temperature) was determined by measuring the viscoelastic spectrum using a viscoelasticity measurement analyzer (ARES, manufactured by Ta Instruments) under conditions of a strain of 0.1% and a frequency of 1 Hz.

[0157] In the examples and comparative examples, the following polymers were used.

[0158] (6) Physical properties of softener (6-1)Kinematic viscosity The kinematic viscosity of the softener was measured at 40°C and 100°C in accordance with the measurement method of ISO3104.

[0159] (6-2) Loss on heating and evaporation The softener sample was weighed and its weight (mass) (W0) before heating was measured. The softener was then heated in an oven (Gear Oven ACR-60, manufactured by Toyo Seiki Seisakusho) and allowed to cool at room temperature for 1 hour, after which its weight (mass) (W1) was measured. The difference (W0-W1) between the weight (mass) before heating (W0) and the weight (mass) after heating (W1) was calculated, and the percentage of this difference (W0-W1) relative to the weight (mass) before heating (W0) was taken as the loss on evaporation due to heating.

[0160] The heating was carried out under three conditions: "200°C x 1 hour in air," "200°C x 3 hours in air," and "200°C x 5 hours in air," and the loss on evaporation due to heating under each condition was determined.

[0161] (6-3) Molecular weight distribution The softener was subjected to gel permeation chromatography (GPC) measurement under the following conditions, and the relative molecular weight (molecular weight in polystyrene equivalent) and its weight fraction (dW / dlogM) at each elution time were determined. A molecular weight distribution curve was then created, and the polystyrene-equivalent weight average molecular weight Mw, number average molecular weight Mn, and Mw / Mn were determined.

[0162] Measurement model: Tosoh Gel Permeation Chromatograph HLC-8321 GPC Column: 2x TSKgel GMH6-HT + 2x TSKgel GMH6-HTL (Both 7.5 mm ID x 30 cm, Tosoh Corporation) Solvent: o-dichlorobenzene; ODCB (containing 0.025% BHT) Column temperature: 140℃ Concentration: 0.1% Flow rate: 1.0mL / min Detector: Differential refractometer (RI) Column calibration: Monodisperse polystyrene (Tosoh Corporation); #3 standard set Molecular weight conversion: Polystyrene conversion / standard conversion method Furthermore, from the molecular weight distribution curve obtained by the GPC measurement, the proportion (R) of components contained in the softener having a relative molecular weight of 600 or less in terms of polystyrene was calculated using the following formula (1).

[0163] R(%)=Im / It×100 Equation (1) It: total peak area of ​​the entire molecular weight distribution Im: Total peak area of ​​polystyrene-equivalent relative molecular weights of 600 or less [Raw materials] In the examples and comparative examples, the following components were used to form the compositions.

[0164] <(A) Polypropylene resin> As component (A), a homopolymer type polypropylene (melt flow rate (MFR) at 230°C and a load of 2.16 kg: 0.5 g / 10 min; weight average molecular weight: 6.6 × 10) manufactured by SunAllomer Co., Ltd. was used. 5 ) (hereinafter referred to as "A-1") was used.

[0165] <(B) Ethylene-α-olefin copolymer> The component (B) used was a copolymer of ethylene and 1-octene (manufactured by The Dow Chemical Company under the trade name "Engage 8842"). The ethylene content of this copolymer was 55% by mass, and the 1-octene content was 45% by mass (hereinafter referred to as "B-1"). <(C) Hydrogenated Block Copolymer> As the hydrogenated block copolymer (C) (hereinafter referred to as component (C)), the following hydrogenated products (C1) and (C2) were used.

[0166] (C1) A hydrogenated copolymer having a copolymer block mainly containing conjugated diene monomer units and further containing vinyl aromatic monomer units, and a vinyl aromatic monomer unit block. Production of hydrogenated products (C1-1) As the hydrogenated copolymer (C1) having a copolymer block mainly containing conjugated diene monomer units and further containing vinyl aromatic monomer units, and a vinyl aromatic monomer unit block, a hydrogenated copolymer (C1-1) (hereinafter referred to as "hydrogenated copolymer (C1-1)") having a copolymer block mainly containing conjugated diene monomer units and further containing vinyl aromatic monomer units, and a vinyl aromatic monomer unit block was prepared as follows.

[0167] (1) Preparation of hydrogenation catalyst The hydrogenation catalyst used in the hydrogenation reaction of the block copolymer was prepared by the following method.

[0168] A nitrogen-substituted reaction vessel was charged with 1 L of dried and purified cyclohexane, and 100 mmol of bis(cyclopentadienyl)titanium dichloride was added. With thorough stirring, an n-hexane solution containing 200 mmol of trimethylaluminum was added, and the mixture was allowed to react at room temperature for approximately 3 days.

[0169] (2) Production of block copolymers Batch polymerization was carried out using a 10 L tank reactor equipped with a stirrer and a jacket. First, 6.4 L of cyclohexane and 75 g of styrene were added. TMEDA was added in advance so that the molar ratio was 0.25 times the number of moles of Li in n-butyllithium. The n-butyllithium initiator was then added so that the number of moles of Li was 10 mmol. A first polymerization reaction was carried out at an initial temperature of 65 °C. After the first polymerization reaction was completed, a cyclohexane solution containing 470 g of butadiene and 380 g of styrene (monomer concentration: 22% by mass) was continuously fed into the reactor at a constant rate over 60 minutes to carry out a second polymerization reaction. After the second polymerization reaction was completed, a cyclohexane solution containing 75 g of styrene (monomer concentration: 22% by mass) was added over 10 minutes to carry out a third polymerization reaction. The third polymerization reaction was then terminated by adding methanol to obtain a copolymer. The styrene content in the obtained copolymer was 53% by mass, the styrene polymer block content in the copolymer was 15% by mass, the styrene content in the copolymer block (i.e., the copolymer block containing conjugated diene monomer units and vinyl aromatic monomer units) was 45% by mass, and the vinyl bond content was 23%.

[0170] The resulting copolymer (block copolymer) was subsequently subjected to the hydrogenation reaction described below in (3).

[0171] (3) Production of hydrogenated block copolymers The hydrogenation catalyst obtained in (1) was added to the block copolymer obtained in (2) in an amount of 100 ppm in terms of titanium per 100 parts by mass of the block copolymer, and the block copolymer was hydrogenated at a hydrogen pressure of 0.7 MPa and a temperature of 75° C. To the polymer solution containing the hydrogenated block copolymer obtained in the hydrogenation reaction, 0.3 parts by mass of octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added as a stabilizer per 100 parts by mass of the hydrogenated block copolymer.

[0172] The weight-average molecular weight of the resulting hydrogenated block copolymer (C1-1) was 160,000, and the hydrogenation rate of the butadiene double bonds contained in the hydrogenated block copolymer (C1-1) was 99%. Furthermore, one of the tan δ peaks obtained by viscoelasticity measurement was present at -15°C.

[0173] (C2) Hydrogenated copolymer having a polymer block consisting of a conjugated diene monomer unit and a vinyl aromatic monomer unit block As the hydrogenated product (C2) of a copolymer having a polymer block composed of conjugated diene monomer units and a vinyl aromatic monomer unit block, hydrogenated products (C2-1) and (C2-2) of a copolymer having a polymer block composed of conjugated diene monomer units and a vinyl aromatic monomer unit block (hereinafter referred to as "hydrogenated product (C2-1)" and "hydrogenated product (C2-2)", respectively) were prepared as follows.

[0174] Production of hydrogenated products (C2-1) (1) Production of block copolymers Batch polymerization was carried out using a 10 L tank reactor equipped with a stirrer and a jacket. First, 6.4 L of cyclohexane and 325 g of styrene were added. TMEDA was added in an amount equivalent to 0.40 times the number of moles of Li in n-butyllithium, and then further added to the reactor in an amount equivalent to 20 mmol of Li in the n-butyllithium initiator. A first polymerization reaction was then carried out at an initial temperature of 65°C. After the first polymerization reaction was completed, a cyclohexane solution containing 350 g of butadiene (monomer concentration: 22% by mass) was continuously fed into the reactor at a constant rate over 60 minutes to carry out a second polymerization reaction. After the second polymerization reaction was completed, a cyclohexane solution containing 325 g of styrene (monomer concentration: 22% by mass) was added over 10 minutes to carry out a third polymerization reaction. The third polymerization reaction was then terminated by the addition of methanol to obtain a copolymer. The resulting copolymer had a styrene polymer block content of 65% by mass and a vinyl bond content of 40%.

[0175] The resulting copolymer (block copolymer) was subsequently subjected to the hydrogenation reaction described below in (2).

[0176] (2) Production of hydrogenated block copolymers To the block copolymer obtained in (1) above, the hydrogenation catalyst obtained in (1) of "Production of Hydrogenated Product (C1-1)" was added in an amount of 100 ppm in terms of titanium per 100 parts by mass of the block copolymer. The block copolymer was then hydrogenated at a hydrogen pressure of 0.7 MPa and a temperature of 75°C. To the polymer solution containing the hydrogenated block copolymer obtained in the hydrogenation reaction, 0.3 parts by mass of octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added as a stabilizer per 100 parts by mass of the hydrogenated block copolymer.

[0177] The weight average molecular weight of the obtained hydrogenated block copolymer (C2-1) was 50,000, and the hydrogenation rate of the butadiene double bonds contained in the hydrogenated block copolymer (C2-1) was 99%.

[0178] Production of hydrogenated products (C2-2) (1) Production of block copolymers Batch polymerization was carried out using a 10 L tank reactor equipped with a stirrer and a jacket. First, 6.4 L of dried and purified cyclohexane and 175 g of styrene were added. Tetramethylethylenediamine (TMEDA) was added in advance so that the molar ratio was 0.30 times the number of moles of Li in the n-butyllithium initiator, resulting in 11 mmol of Li in the n-butyllithium initiator. Then, a first polymerization reaction was carried out at an initial temperature of 65°C. After the first polymerization reaction was completed, a cyclohexane solution containing 650 g of butadiene (monomer concentration: 22% by mass) was continuously fed into the reactor at a constant rate over 60 minutes to carry out a second polymerization reaction. After the second polymerization reaction was completed, a cyclohexane solution containing 175 g of styrene (monomer concentration: 22% by mass) was further added over 10 minutes to carry out a third polymerization reaction. The third polymerization reaction was then terminated by adding methanol to obtain a copolymer. The resulting copolymer had a styrene polymer block content of 35% by mass and a vinyl bond content of 36%.

[0179] The resulting copolymer (block copolymer) was subsequently subjected to the hydrogenation reaction described below in (2).

[0180] (2) Production of hydrogenated block copolymers To the block copolymer obtained in (1) above, the hydrogenation catalyst obtained in (1) of "Production of Hydrogenated Product (C1-1)" was added so as to give 100 ppm titanium equivalent per 100 parts by mass of the block copolymer, and the block copolymer was hydrogenated at a hydrogen pressure of 0.7 MPa and a temperature of 75°C to obtain a reaction solution. To the obtained reaction solution, 0.3 parts by mass of octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was added as a stabilizer per 100 parts by mass of the hydrogenated block copolymer.

[0181] The weight average molecular weight of the obtained hydrogenated block copolymer (C2-2) was 150,000, and the hydrogenation rate of the butadiene double bonds contained in the hydrogenated block copolymer (C2-2) was 99%.

[0182] <(D) Softeners, etc.> As the softener (D) (hereinafter referred to as component (D)), a paraffinic oil (hereinafter referred to as "D-1") having the physical properties shown in Table 1 below was used. For reference, the following softeners related to D are listed: Out Manufactured by Mitsukosan Co., Ltd., product name "Diana Process Oil PW-380 」 Table 1 also shows the physical properties of the softener (hereinafter referred to as "D-2") prepared according to Example 1 of JP-A No. 2001-294714 (hereinafter referred to as "D-3").

[0183] In addition, a paraffinic oil (manufactured by Idemitsu Kosan Co., Ltd., trade name "Diana Process Oil PW-100") (hereinafter referred to as "D'-1") was used as a softener other than component (D) (hereinafter referred to as "component (D')"). For reference, the physical properties of softener (D'-2) (manufactured by Idemitsu Kosan Co., Ltd., trade name "Diana Process Oil PW-90") (hereinafter referred to as "D'-2"), which is a softener related to the above-mentioned D', are also shown in Table 1.

[0184] The physical properties of D-1 and D'-1 are shown in Table 1 below, along with the physical properties of D-2, D-3 and D'-2.

[0185] [Table 1] <(E) Polyorganosiloxane> As the polyorganosiloxane (E) (referred to as component (E)), dimethylsiloxane (manufactured by Toray Dow Corning Co., Ltd., trade name "SH200"; kinematic viscosity 60,000 centistokes (cSt) (i.e., 60,000 mm 2 / s)) (hereinafter referred to as "E-1") was used.

[0186] <Crosslinking agents and crosslinking aids> The crosslinking agent was mixed with the following crosslinking coagent and the following softener and used in the form of a crosslinking agent mixture.

[0187] Here, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (manufactured by NOF Corporation, trade name "Perhexa 25B") was used as the crosslinking agent.

[0188] The crosslinking aid (polyfunctional monomer) and softener blended with the crosslinking agent are as follows: Here, the amounts of the crosslinking aid and softener are based on 100 parts by mass of the crosslinking agent.

[0189] Crosslinking aid 1 (triallyl isocyanurate (manufactured by Nippon Kasei Co., Ltd.; hereinafter referred to as "TAIC")) 35 parts by mass Crosslinking aid 2 (divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.; hereinafter referred to as "DVB")) 17 parts by mass 143 parts by weight of softener (manufactured by Idemitsu Kosan Co., Ltd., product name "Diana Process Oil PW-100") [Example 1 and Comparative Example 1] The extruder used was a twin-screw extruder (40 mmφ, L / D=47; manufactured by Toshiba Machine Co., Ltd., "TEM58SS") with an oil inlet in the center of the barrel. The screw used was a two-start screw with kneading sections before and after the inlet.

[0190] The raw materials listed in Table 2 below, except for the softener (component (D) and other softeners (component (D'))), were mixed together in the composition ratios (parts by mass) listed in Table 2 below, and then introduced into a twin-screw extruder (cylinder temperature 200°C) using a constant volume feeder. Subsequently, a predetermined amount of softener was injected using a pump through an injection port located in the center of the twin-screw extruder, and melt extrusion was carried out to obtain a thermoplastic elastomer composition. This thermoplastic elastomer composition was used as an evaluation sample in the physical property evaluations of "(1) Melt Flow Rate (MFR)" and "(4) Fogging Resistance" described above.

[0191] The obtained thermoplastic elastomer composition was compression molded at 200°C using a heated press ("T-50" manufactured by Toho Press Manufacturing Co., Ltd.) to produce a 2 mm thick sheet. The obtained 2 mm thick sheet was used as an evaluation sample for the physical property evaluation of "(2) Surface hardness (Shore-A hardness)" and "(3) Mechanical properties (tensile strength and tensile elongation)".

[0192] The raw material composition and the results of the physical property evaluation are shown in Table 2 below.

[0193] [Table 2]

Claims

1. A thermoplastic elastomer composition comprising the following components (A) to (E), which is at least partially crosslinked: (A) 100 parts by mass of polypropylene resin; (B) 40 to 80 parts by mass of an ethylene / α-olefin copolymer containing ethylene units and α-olefin units having 3 to 20 carbon atoms; (C) 80 to 200 parts by mass of a hydrogenated block copolymer which is a hydrogenated product of a block copolymer having at least one block (c1) mainly composed of conjugated diene monomer units and at least one block (c2) mainly composed of vinyl aromatic monomer units; (D) 100 to 250 parts by mass of a softener, in which the proportion (R) of components having a relative molecular weight of 600 or less in terms of polystyrene, as measured by gel permeation chromatography (GPC), is 23% or less; (E) Polyorganosiloxane: 5 to 20 parts by mass.

2. The kinematic viscosity of the softener (D) at 40°C is 300 mm 2 The thermoplastic elastomer composition according to claim 1, wherein the viscosity is 1 / s or less.

3. 3. The thermoplastic elastomer composition according to claim 1 or 2, wherein the softener (D) has an amount of aerosol compounds measured in accordance with VDA278 of 1000 μg / g or less.

4. The thermoplastic elastomer composition according to claim 1 or 2, wherein the softener (D) has an evaporation loss of 0.2 mass% or less at 200°C and atmospheric pressure for 1 hour.

5. The thermoplastic elastomer composition according to claim 1 or 2, which satisfies the following requirements (1) to (3): (1) The melt flow rate (MFR, 230°C, 1.2 kg load) measured in accordance with ASTM D1238 is 30 to 100 g / 10 min. (2) The surface hardness (Shore-A hardness, instantaneous value) measured in accordance with JIS K7215 is 60 to 100. (3) The tensile elongation measured in accordance with JIS K6251 is 100% or more.

6. The hydrogenated block copolymer (C) 3. The thermoplastic elastomer composition according to claim 1, comprising a hydrogenated block copolymer (C1) that is a hydrogenated product of a block copolymer having at least one block (c11) that mainly contains conjugated diene monomer units and further contains vinyl aromatic monomer units, and at least one block (c2) that mainly contains vinyl aromatic monomer units.

7. 7. The thermoplastic elastomer composition according to claim 6, wherein the content of the hydrogenated block copolymer (C1) relative to 100 parts by mass of the polypropylene resin (A) is 50 parts by mass or more and less than 80 parts by mass.

8. An injection-molded article comprising the thermoplastic elastomer composition according to claim 1 or 2.

9. A film or sheet comprising the injection-molded article according to claim 8.

10. An automobile interior material comprising the injection molded article according to claim 8.

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