Thermoplastic elastomer composition and molded article formed therefrom

Abstract

The purpose of the present invention is to provide: a thermoplastic elastomer which has low viscosity and excellent flowability, is capable of reducing hue unevenness, and is capable of further reducing environmental burden when a biomass-derived softening agent is used; and a molded article. A thermoplastic elastomer composition containing: (A) 100 parts by mass of a polypropylene resin; (B) 40-80 parts by mass of an ethylene-alpha-olefin copolymer containing an ethylene unit and an alpha-olefin unit having 3-20 carbon atoms; (C) 80-200 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 a conjugated diene monomer unit and at least one block (c2) mainly composed of a vinyl aromatic monomer unit, (D) 20-150 parts by mass of a softening agent, the content of paraffin-based carbon atoms (% CP) of the softening agent as measured in accordance with ASTM D3238-85 or ASTM D2140 is from 80% to 100% (inclusive), and at least a portion of the thermoplastic elastomer composition is crosslinked.

Description

Technical Field

[0001] The present invention relates to a thermoplastic elastomer composition and a molded article formed therefrom. Background Art

[0002] Due to the increasing environmental awareness and the expected reduction in the reserves of fossil resources such as natural gas, the importance of bioplastics containing materials obtained from biomass-derived raw materials is increasing day by day.

[0003] Among plastic materials, thermoplastic elastomers are an industrially important polymer group and are used in various applications such as the automotive field, consumer products, packaging, pharmaceuticals, and the construction field. Therefore, even for materials containing thermoplastic elastomers, a reduction in environmental load is required.

[0004] For example, Patent Document 1 discloses a polymer composition containing a thermoplastic elastomer, rubber or bioplastic, and a plasticizer, which is a plant-based raw material, or a raw material product based on industrial plants, or a raw material product based on animal-derived fat sources.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-529688 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] For thermoplastic elastomer compositions, depending on their uses, molding methods, etc., low viscosity, excellent fluidity, and little hue unevenness are required. However, in Patent Document 1, it is not clear what conditions are required to make the composition have low viscosity, excellent fluidity, and reduced hue unevenness.

[0010] Therefore, an object of the present invention is to provide a thermoplastic elastomer and a molded article that have low viscosity, excellent fluidity, can reduce hue unevenness, and can further reduce the environmental load when using a biomass-derived softening agent.

[0011] Means for Solving the Problems

[0012] The present inventors conducted in-depth research to solve the above problems and found that a thermoplastic elastomer composition containing a polypropylene-based resin, an ethylene-α-olefin copolymer, a hydrogenated block copolymer, and a softening agent in specific blending ratios, and the softening agent being a softening agent that satisfies specific conditions, and a molded article containing the thermoplastic elastomer composition can solve the above problems, thereby completing the present invention.

[0013] That is, the present invention relates to the following [1] to

[15] .

[0014] [1] A thermoplastic elastomer composition, which contains the following components (A) to (D) and is at least partially crosslinked.

[0015] (A) 100 parts by mass of a polypropylene resin;

[0016] (B) 40 to 80 parts by mass of an ethylene-α-olefin copolymer, which contains ethylene units and α-olefin units having 3 to 20 carbon atoms;

[0017] (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 a conjugated diene monomer unit and at least one block (c2) mainly composed of a vinyl aromatic monomer unit;

[0018] (D) 20 to 250 parts by mass of a softening agent, the content (%) of paraffin-based carbon atoms measured according to ASTM D3238-85 or ASTM D2140 P is 80% or more and 100% or less.

[0019] [2] The thermoplastic elastomer composition according to [1], wherein the softening agent (D) contains a biomass-derived softening agent.

[0020] [3] The thermoplastic elastomer composition according to [1], wherein the softening agent (D) is a biomass-derived softening agent.

[0021] [4] The thermoplastic elastomer composition according to any one of [1] to [3], wherein the kinematic viscosity of the softening agent (D) at 40°C is 40 mm 2 / s or more and 150 mm 2 / s or less.

[0022] [5] The thermoplastic elastomer composition according to any one of [1] to [4], wherein the density of the softening agent (D) at 15°C is 865 kg / m 3 or less.

[0023] [6] The thermoplastic elastomer composition according to any one of [1] to [5], wherein the pour point of the softening agent (D) is -10°C or less.

[0024] [7] The thermoplastic elastomer composition according to any one of [1] to [5], wherein the polypropylene resin (A) is at least one selected from the group consisting 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.

[0025] [8] The thermoplastic elastomer composition according to any one of [1] to [7], wherein the aforementioned polypropylene-based resin (A) is composed only of an atactic polypropylene.

[0026] [9] The thermoplastic elastomer composition according to any one of [1] to [8], further comprising a lubricant.

[0027]

[10] The thermoplastic elastomer composition according to [9], wherein the aforementioned lubricant contains a polyorganosiloxane.

[0028]

[11] The thermoplastic elastomer composition according to any one of [1] to

[10] , further comprising a crosslinking agent.

[0029]

[12] The thermoplastic elastomer composition according to

[11] , wherein, relative to 100 parts by mass of the aforementioned polypropylene-based resin (A), 2 parts by mass or more of the aforementioned crosslinking agent is contained.

[0030]

[13] An injection molded article comprising the thermoplastic elastomer composition according to any one of [1] to

[12] .

[0031]

[14] A film or sheet formed from the injection molded article according to

[13] .

[0032]

[15] An automotive interior material formed from the injection molded article according to

[13] .

[0033] Advantages of the Invention

[0034] According to the present invention, it is possible to provide a thermoplastic elastomer composition and a molded article that have low viscosity and excellent fluidity, can reduce hue unevenness, and can further reduce the environmental load when using a softening agent derived from biomass. Detailed Description of the Invention

[0035] Hereinafter, the specific embodiments of the present invention will be described in detail, but the present invention is not limited to any of the following embodiments, and appropriate modifications can be made within the scope of the object of the present invention for implementation.

[0036] Here, in the present specification, the term "polymer" is used to include both homopolymers and copolymers unless otherwise specified.

[0037] In the present specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0038] In addition, in the present specification, when referring to the amount of each component in the composition, in the case where there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the multiple substances present in the composition.

[0039] [Thermoplastic elastomer composition]

[0040] The thermoplastic elastomer composition of the present invention contains the following components (A) to (D) and is at least partially crosslinked:

[0041] (A) 100 parts by mass of a polypropylene-based resin;

[0042] (B) 40 to 80 parts by mass of an ethylene-α-olefin copolymer containing an ethylene unit and an α-olefin unit having 3 to 20 carbon atoms;

[0043] (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 a conjugated diene monomer unit and at least one block (c2) mainly composed of a vinyl aromatic monomer unit;

[0044] (D) 20 to 250 parts by mass of a softening agent, the content of paraffinic carbon atoms (%) C P ) measured according to ASTM D3238-85 or ASTM D2140 is 80% or more and 100% or less.

[0045] Hereinafter, the thermoplastic elastomer composition of the present invention will be described in detail.

[0046] [Polypropylene-based resin (A)]

[0047] The polypropylene-based resin (A) used in the present invention is a homopolymer of propylene or a copolymer of propylene and an olefin other than propylene. In the present invention, the polypropylene-based resin (A) is preferably at least one polypropylene-based resin selected from the group consisting 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.

[0048] As a suitable raw material olefin other than propylene for the polypropylene-based resin (A), an α-olefin having 2 or 4 to 20 carbon atoms is preferred. Specifically, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene, etc. can be cited. When the polypropylene-based resin (A) is a copolymer of propylene and an olefin other than propylene, the polymerization method can be a random type or a block type as long as a resinous substance can be obtained. These polypropylene-based resins can be used alone or in combination of two or more.

[0049] The polypropylene-based resin (A) used in the present invention is preferably a polypropylene-based polymer having a propylene content of 40 mol% or more, and more preferably a polypropylene-based polymer having a propylene content of 50 mol% or more.

[0050] Among these polypropylene-based resins (A), propylene homopolymers, propylene-ethylene block copolymers, propylene-ethylene random copolymers, propylene-ethylene-butene random copolymers, etc. are more preferably used. In addition, from the viewpoint of heat resistance, the polypropylene-based resin (A) is particularly preferably composed only of a propylene homopolymer.

[0051] The melting point of the polypropylene-based resin (A) used in the present invention is usually 80 to 170 °C, preferably in the range of 120 to 170 °C.

[0052] The MFR (ASTM D1238-65T, 230 °C, 2.16 kg load) of the polypropylene-based resin (A) used in the present invention is usually 0.01 to 100 g / 10 minutes, preferably in the range of 0.05 to 50 g / 10 minutes.

[0053] Regarding the polypropylene-based resin (A) used in the present invention, as a stereostructure, an isotactic structure is preferred, but a syndiotactic structure, a structure formed by mixing these structures, or a structure containing a part of an atactic structure may also be used.

[0054] The polypropylene-based resin (A) used in the present invention is polymerized by various known polymerization methods.

[0055] In addition, the polypropylene-based resin (A) used in the present invention may be a polymer obtained by using only fossil fuel-derived olefins such as propylene from fossil fuels as raw materials, a polymer obtained by using only biomass-derived olefins such as propylene from biomass as raw materials, or a polymer obtained by using a mixture of fossil fuel-derived olefins and biomass-derived olefins as raw materials, or may also be a mixture of two or more of these polymers.

[0056] Here, fossil fuel refers to substances such as petroleum, coal, natural gas, and shale gas that have been fossilized by the accumulation and pressurization of the remains of animals and plants over hundreds of millions of years. Fossil fuel-derived olefins are olefins obtained from such fossil fuels. Since it has passed a sufficiently long time compared to the half-life of 5,730 years of 14 C isotope, no 14 C can be detected from fossil-derived carbon.

[0057] In addition, biomass refers to all renewable natural raw materials and their residues of plant origin or animal origin, including fungi, yeast, algae, and bacteria. Biomass-derived olefins are olefins obtained from such biomass. Biomass-derived carbon contains a certain amount of 14 C isotope as carbon (in a proportion of about 10 -12 %).

[0058] <Ethylene-α-olefin copolymer (B)>

[0059] 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.

[0060] Specific examples of the α-olefin include, for example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene. Among them, from the viewpoint of economy, α-olefins having 3 to 12 carbon atoms are preferred, and propylene, 1-butene, and 1-octene are more preferred.

[0061] The ethylene-α-olefin copolymer (B) may further contain monomer units having an unsaturated bond as needed. The monomer is not particularly limited, and from the viewpoint of economy, conjugated dienes such as butadiene and isoprene, non-conjugated dienes such as 1,4-hexadiene, cyclic diene compounds such as dicyclopentadiene and norbornene derivatives, and acetylenes are preferred, and among them, ethylidene norbornene (ENB) and dicyclopentadiene (DCP) are more preferred.

[0062] The Mooney viscosity (ML) of the ethylene-α-olefin copolymer (B) measured at 100 °C is not particularly limited, and from the viewpoint of dispersibility in the thermoplastic elastomer composition of the present invention, it is preferably 20 to 150, more preferably 50 to 120. The Mooney viscosity (ML) of the ethylene-α-olefin copolymer (B) can be measured by ASTM D1646.

[0063] The ethylene-α-olefin copolymer (B) is preferably produced using a metallocene catalyst. The metallocene catalyst is not particularly limited, and examples thereof include catalysts composed of cyclopentadienyl derivatives of Group IV metals such as titanium and zirconium and cocatalysts. The metallocene catalyst not only has high activity as a polymerization catalyst, but also has a narrow molecular weight distribution of the obtained polymer compared with Ziegler catalysts and the like, and can make the distribution of α-olefin monomers having 3 to 20 carbon atoms as a comonomer in the copolymer more uniform.

[0064] In addition, the ethylene-α-olefin copolymer (B) used in the present invention may be a polymer obtained by using only olefins derived from fossil fuels such as ethylene and α-olefins derived from fossil fuels, a polymer obtained by using only olefins derived from biomass such as ethylene and α-olefins derived from biomass, or a polymer obtained by using a mixture of olefins derived from fossil fuels and olefins derived from biomass, or may also be a mixture of two or more of these polymers.

[0065] The copolymerization ratio of the α-olefin in the ethylene-α-olefin copolymer (B) is not particularly limited, preferably 1 to 60% by mass, more preferably 10 to 50% by mass, and still more preferably 20 to 45% by mass. By setting the copolymerization ratio of the α-olefin within the above range, the mechanical strength such as the tensile strength of the molded product and the flexibility are further improved.

[0066] The density of the ethylene-α-olefin copolymer (B) is not particularly limited, preferably 0.80 to 0.90 g / cm 3 , more preferably 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 product is further improved.

[0067] The ethylene-α-olefin copolymer (B) preferably has long branches. Here, the long branches refer to branches having 3 or more carbon atoms. By having long branches, a molded product with high strength and low density can be obtained. As the ethylene-α-olefin copolymer having long branches, there is no particular limitation, and known substances can be used. For example, substances described in U.S. Patent No. 5,278,272 can also be used.

[0068] The ethylene-α-olefin copolymer (B) preferably has a melting point peak in differential scanning calorimetry (DSC) in the temperature range above room temperature. By having a melting point peak in the temperature range above room temperature for the ethylene-α-olefin copolymer (B), a molded product with excellent morphological stability, processability, and less stickiness in the temperature range below the melting point can be produced.

[0069] The MFR (at 190 °C, 2.16 kg load; according to ASTM D1238) of the ethylene-α-olefin copolymer (B) is not particularly limited, preferably 0.01 to 100 g / 10 minutes, more preferably 0.2 to 10 g / 10 minutes. By setting the MFR within the above range, a molded product with excellent balance characteristics of molding fluidity and mechanical strength can be produced.

[0070] From the viewpoint of the balance of molding fluidity, hue unevenness, and flexibility, the content of the ethylene-α-olefin copolymer (B) is 40 to 80 parts by mass, preferably 50 to 70 parts by mass, based on 100 parts by mass of the aforementioned polypropylene resin (A).

[0071] <Hydrogenated block copolymer (C)>

[0072] The hydrogenated block copolymer (C) used in the present invention is a hydride of a block copolymer having at least one block (c1) mainly composed of conjugated diene monomer units (sometimes referred to as "block (c1)" in this specification) and at least one block (c2) mainly composed of vinyl aromatic monomer units (sometimes referred to as "block (c2)" in this specification). Herein, the "vinyl aromatic monomer unit" refers to a structural unit of a polymer produced by polymerizing a vinyl aromatic compound as a monomer, and its structure is a molecular structure in which two carbons of a substituted ethylidene derived from a substituted vinyl are bonding sites. In addition, the "conjugated diene monomer unit" refers to a structural unit of a polymer produced by polymerizing a conjugated diene as a monomer, and its structure is a molecular structure in which two carbons of an olefin of the conjugated diene monomer are bonding sites. "Mainly" in the block copolymer means that in the copolymer block, the monomer units derived from the conjugated diene monomer (or vinyl aromatic monomer) are contained in an amount of 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more. For example, a block mainly composed of conjugated diene monomer units means that in the block, the monomer units derived from the conjugated diene monomer are contained in an amount of 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more. Similarly, a block mainly composed of vinyl aromatic monomer units means that in the block, the monomer units derived from the vinyl aromatic monomer are contained in an amount of 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more.

[0073] Herein, as an example of the block (c1) mainly composed of conjugated diene monomer units, there can be mentioned: a homopolymer block (c10) composed only of conjugated diene monomer units (sometimes referred to as "polymer block (c10)" in this specification), and a copolymer block (c11) containing conjugated diene monomer units as the main component and also containing vinyl aromatic monomer units (sometimes referred to as "copolymer block (c11)" in this specification).

[0074] In addition, as an example of the block (c2) mainly composed of vinyl aromatic monomer units (hereinafter sometimes referred to as "block (c2)"), there can be mentioned: a homopolymer block (c20) composed only of vinyl aromatic monomer units, and a copolymer block (c21) containing vinyl aromatic monomer units as the main component and also containing conjugated diene monomer units.

[0075] 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. They can be used alone or in combination of two or more. Among them, styrene is preferred from the viewpoint of economy.

[0076] In the present embodiment, the conjugated diene monomer is a diene 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, 1,3-hexadiene, and the like. Among them, from the viewpoint of economy, butadiene and isoprene are preferred. They may be used alone or in combination of two or more.

[0077] In addition, the above-mentioned monomers as raw materials for the hydrogenated block copolymer (C2) may be any one of biomass-derived monomers, fossil fuel-derived monomers, or a mixture thereof.

[0078] The arrangement of each block in the hydride of the block copolymer of the present embodiment is not particularly limited, and a suitable arrangement can be appropriately adopted. For example, in the case where S represents a polymer block composed of vinyl aromatic monomer units and B represents a polymer block composed of conjugated diene monomer units and / or partially hydrogenated units thereof, examples of the hydride of the block copolymer include SB, S(BS) n1 (where n1 represents an integer of 1 to 3), S(BSB) n2 (where n2 represents an integer of 1 to 2), etc., linear block copolymers represented by (SB) n3 X (where n3 represents an integer of 3 to 6, and X represents a coupling agent residue such as silicon tetrachloride, tin tetrachloride, polyepoxide, etc.). Among them, linear block copolymers of type 2 (diblock) of SB, type 3 (triblock) of SBS, and type 4 (tetrablock) of SBSB are preferred.

[0079] The content of the vinyl aromatic monomer units in the hydrogenated block copolymer (C) is 30 to 80% by mass, and from the viewpoints of heat resistance and dispersibility, it is preferably 40 to 80% by mass, and more preferably 50 to 70% by mass. By setting the content of the vinyl aromatic monomer units to 30% by mass or more, the mechanical properties are further improved, and by setting it to 80% by mass or less, the low-temperature properties can be further improved. The content of the vinyl aromatic monomer units in the hydrogenated block copolymer (C) can be measured by nuclear magnetic resonance spectroscopy (NMR).

[0080] 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) can be obtained by the method of oxidatively decomposing the copolymer before hydrogenation using osmium tetroxide as a catalyst and tert-butyl hydroperoxide (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").), the mass of the vinyl aromatic compound polymer block (here, excluding vinyl aromatic compound polymers with an average degree of polymerization of about 30 or less) is defined by the following formula.

[0081] Content of vinyl aromatic compound polymer block (% by mass) = (mass of vinyl aromatic compound polymer block in copolymer before hydrogenation / mass of copolymer before hydrogenation) × 100

[0082] When there are multiple polymer blocks in the hydrogenated block copolymer (C), the molecular weights, compositions, and other structures of each can be the same or different. For example, in the hydrogenated block copolymer (C), there may be a hydrogenated copolymer block containing a conjugated diene monomer unit and a vinyl aromatic monomer unit, and a hydrogenated copolymer block mainly composed of a conjugated diene monomer unit. The boundaries and ends of each block do not necessarily need to be clearly distinguished. The distribution pattern of the vinyl aromatic monomer units in each polymer block is not particularly limited and can be uniformly distributed or distributed in a cone shape, step shape, convex shape, or concave shape. In addition, a crystalline part may also be present in the polymer block.

[0083] The distribution pattern of the vinyl units of the conjugated diene monomer units in each polymer block is not particularly limited. For example, the distribution may be biased. As a method for controlling the distribution of vinyl units, methods such as adding a vinylating agent during polymerization and changing the polymerization temperature can be cited. In addition, the distribution of the hydrogenation rate of the conjugated diene monomer units may be biased. The distribution of the hydrogenation rate can be controlled by methods such as changing the distribution state of vinyl units, copolymerizing isoprene and butadiene and then hydrogenating using the hydrogenation catalyst described later and utilizing the difference in the hydrogenation rates of isoprene units and butadiene units.

[0084] From the viewpoints of heat resistance, aging resistance, and weather resistance, in the hydrogenated block copolymer (C), among the unsaturated bonds contained in the conjugated diene monomer units before hydrogenation, it is preferred that 75 mol% or more, more preferably 85 mol% or more, and still more preferably 97 mol% or more are hydrogenated.

[0085] The hydrogenation catalyst used for hydrogenation is not particularly limited, and known (1) supported heterogeneous hydrogenation catalysts in which carbon, silica, alumina, diatomaceous earth, etc. are supported on metals such as Ni, Pt, Pd, Ru, etc.; (2) so-called Ziegler-type hydrogenation catalysts using transition metal salts such as organic acid salts or acetylacetonate salts of Ni, Co, Fe, Cr, etc. and reducing agents such as organoaluminum; (3) homogeneous hydrogenation catalysts such as organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, etc. As specific hydrogenation catalysts, the hydrogenation catalysts described in Japanese Patent Publication No. Sho 42-008704, Japanese Patent Publication No. Sho 43-006636, Japanese Patent Publication No. Sho 63-004841, Japanese Patent Publication No. Hei 01-037970, Japanese Patent Publication No. Hei 01-053851, Japanese Patent Publication No. Hei 02-009041, etc. can be used. Among them, as a preferred hydrogenation catalyst, a reducing organometallic compound such as a titanocene compound can be mentioned.

[0086] As the titanocene compound, for example, the compounds described in Japanese Patent Laid-Open No. Hei 08-109219 can be used. As specific examples, compounds having at least one ligand having a (substituted) cyclopentadienyl skeleton, indenyl skeleton or fluorenyl skeleton such as dicyclopentadienyl titanium dichloride and monopenta-methylcyclopentadienyl titanium trichloride can be mentioned.

[0087] As the reducing organometallic compound, for example, organoalkali metal compounds such as organolithium, organomagnesium compounds, organoaluminum compounds, organoboron compounds, organozinc compounds, etc. can be mentioned.

[0088] In the present embodiment, the polymerization method of the hydrogenated block copolymer (C) before hydrogenation is not particularly limited, and a known method can also be adopted. For example, the methods described in Japanese Patent Publication No. Sho 36-019286, Japanese Patent Publication No. Sho 43-017979, Japanese Patent Publication No. Sho 46-032415, Japanese Patent Publication No. Sho 49-036957, Japanese Patent Publication No. Sho 48-002423, Japanese Patent Publication No. Sho 48-004106, Japanese Patent Publication No. Sho 56-028925, Japanese Patent Laid-Open No. Sho 59-166518, Japanese Patent Laid-Open No. Sho 60-186577, etc. can be mentioned.

[0089] As needed, 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 acyl halide group, an acid anhydride group, a thiocarboxylic acid group, an aldehyde group, a thioaldehyde group, a carboxylic acid ester group, an amide group, a sulfonic acid group, a sulfonic acid ester group, a phosphoric acid group, a phosphoric acid ester group, an amino group, an imino group, a nitrile group, a pyridyl group, a quinolinyl group, an epoxy group, a thioepoxy group, a thioether group, an isocyanate group, an isothiocyanate group, a halogenated silyl group, an alkoxysilyl group, a halogenated stannyl group, a boric acid group, a boron-containing group, a borate group, an alkoxytin group, a phenyltin group, etc.

[0090] From the viewpoints of flexibility and scratch resistance, the vinyl bond content in the conjugated diene monomer unit in the copolymer before hydrogenation in the hydrogenated block copolymer (C) is preferably 5 mol% or more, and from the viewpoints of productivity, elongation at break, and scratch resistance, it is preferably 70 mol% or less. The vinyl bond content in the conjugated diene monomer unit is more preferably 10 to 50 mol%, further preferably 10 to 30 mol%, and still further preferably 10 to 25 mol%.

[0091] The vinyl bond content referred to herein means the ratio of the bonds incorporated in the form of 1,2-bonds and 3,4-bonds among the bonds incorporated in the conjugated diene before hydrogenation in the forms of 1,2-bonds, 3,4-bonds, and 1,4-bonds. The vinyl bond content can be measured by NMR.

[0092] The weight-average molecular weight of the hydrogenated block copolymer (C) before crosslinking is not particularly limited. From the viewpoint of scratch resistance, it is preferably 50,000 or more, and from the viewpoint of molding fluidity, it is preferably 400,000 or less, more preferably 50,000 to 300,000. The molecular weight distribution (Mw / Mn: weight-average molecular weight / number-average molecular weight) is not particularly limited. From the viewpoint of scratch resistance, a value close to 1 is preferred. The weight-average molecular weight and the number-average molecular weight can be determined by gel permeation chromatography (GPC; manufactured by Shimadzu Corporation, apparatus name "LC-10"), column: TSKgel GMHXL (4.6 mm ID × 30 cm, 2 pieces) in a solvent using tetrahydrofuran (1.0 mL / minute) under the condition of an oven temperature of 40°C. The weight-average molecular weight (Mw), the number-average molecular weight (Mn), and the molecular weight distribution (Mw / Mn) are calculated as polystyrene-equivalent molecular weights.

[0093] The content of the hydrogenated block copolymer (C) is 80 to 200 parts by mass with respect to 100 parts by mass of the aforementioned polypropylene-based resin (A). From the viewpoint of the balance between scratch resistance and flexibility, it is preferably 90 to 170 parts by mass. When the content of the hydrogenated block copolymer (C) is less than 80 parts by mass, the flexibility and scratch resistance are insufficient, and when it exceeds 200 parts by mass, the mechanical properties may sometimes be poor.

[0094] The hydrogenated block copolymer (C) preferably contains a hydrogenated block copolymer (C1), which is a hydrogenated product of a block copolymer having at least one copolymer block (c11) having at least one block (c1) mainly composed of the conjugated diene monomer unit and at least one block (c2) mainly composed of the vinyl aromatic monomer unit. The copolymer block (c11) is a copolymer block containing the conjugated diene monomer unit as the main component and also containing the vinyl aromatic monomer unit. In this case, the hydrogenated block copolymer (C) may be composed only of the aforementioned hydrogenated block copolymer (C1), or in addition to the aforementioned hydrogenated block copolymer (C1), it may further contain a hydrogenated block copolymer (C2), which is a hydrogenated product of a block copolymer composed of one or more polymer blocks (c10) formed by the conjugated diene monomer unit and one or more blocks (c2) mainly composed of the vinyl aromatic monomer unit.

[0095] The copolymer block (c11) mainly composed of the conjugated diene monomer unit and also containing the vinyl aromatic monomer unit is not particularly limited, and the above-mentioned conjugated diene monomer and vinyl aromatic monomer can be used. Among them, from the viewpoint of the balance between mechanical strength and impact resistance, as a preferred combination, there can be mentioned a block containing a butadiene unit and a styrene unit, a block containing an isoprene unit and a styrene unit, etc.

[0096] The copolymer block (c11) only needs to contain at least the conjugated diene monomer unit as the main component, and the content of each monomer is not particularly limited. Especially from the viewpoint of the balance between mechanical strength and impact resistance, the content of the vinyl aromatic monomer unit 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.

[0097] In addition, as the conjugated diene monomer constituting the polymer block (c10) formed by the conjugated diene monomer unit, the above-mentioned conjugated diene monomer can be used. Such a polymer block (c10) is typically a homopolymer block composed only of the conjugated diene monomer unit. As a preferred example, there can be mentioned a homopolymer block composed only of butadiene units, a homopolymer block composed only of isoprene units, etc. However, as long as the polymer block (c10) can exhibit the same effect as a homopolymer block composed only of the conjugated diene monomer unit, the presence of monomer units other than the conjugated diene monomer unit is not necessarily completely excluded. For example, it may also contain a trace amount of vinyl aromatic monomer units inevitably mixed in during the manufacturing process.

[0098] On the other hand, as described above, the block (c2) mainly composed of vinyl aromatic monomer units may be a homopolymer block (c20) composed only of vinyl aromatic monomer units, or may also be a copolymer block (c21) containing vinyl aromatic monomer units as the main component and further containing conjugated diene monomer units. Preferably, it is a homopolymer block (c20) composed only of vinyl aromatic monomer units.

[0099] Here, the aforementioned hydrogenated block copolymer (C1) can be obtained from the aforementioned vinyl aromatic monomer and the aforementioned conjugated diene monomer by the above method. For example, after obtaining a block copolymer through a process including (Process A1) and (Process A2), (Process A3) can be carried out to obtain:

[0100] (Process A1) A process of forming a block (c2) mainly composed of vinyl aromatic monomer units from a vinyl aromatic monomer;

[0101] (Process A2) A process of copolymerizing a conjugated diene monomer and a vinyl aromatic monomer with respect to the block (c2) obtained in the aforementioned Process A1;

[0102] (Process A3) A process of reacting the aforementioned block copolymer with hydrogen in the presence of the aforementioned hydrogenation catalyst.

[0103] On the other hand, for the aforementioned hydrogenated block copolymer (C2), it can also be obtained from the aforementioned vinyl aromatic monomer and the aforementioned conjugated diene monomer by the above method. For example, after obtaining a block copolymer through a process including (Process B1) and (Process B2), (Process B3) can be carried out to obtain:

[0104] (Process B1) A process of forming a block (c2) mainly composed of vinyl aromatic monomer units from a vinyl aromatic monomer;

[0105] (Process B2) A process of polymerizing a conjugated diene monomer with respect to the block (c2) obtained in the aforementioned Process A1;

[0106] (Process B3) A process of reacting the aforementioned block copolymer with hydrogen in the presence of the aforementioned hydrogenation catalyst.

[0107] In addition, as the hydrogenated block copolymer (C), it is preferable to use in combination at least two or more hydrogenated block copolymers including (C-1) a hydrogenated block copolymer having a vinyl aromatic monomer unit block content of 20% by mass or more and less than 50% by mass and (C-2) a hydrogenated block copolymer having a vinyl aromatic monomer unit block content of 50% by mass or more and 80% by mass or less. The (C-1) component with a small content of vinyl aromatic monomer units contributes to the low-temperature properties of the thermoplastic elastomer composition, and the (C-2) component with a large content of vinyl aromatic monomer units contributes to the morphological stabilization of the matrix and domains of the thermoplastic elastomer composition. From the viewpoints of low-temperature properties and mechanical properties, the mass ratio (C-1 / C-2) of the (C-1) component to the (C-2) component is preferably 90 / 10 to 60 / 40. For example, when the hydrogenated block copolymer (C) contains two or more of the aforementioned hydrogenated block copolymers (C2), it is preferable that one or more of the aforementioned hydrogenated block copolymers (C2) constitute the aforementioned (C-1) component, and one or more of the aforementioned hydrogenated block copolymers (C2) constitute the aforementioned (C-2) component. In addition, when the hydrogenated block copolymer (C) contains the aforementioned hydrogenated block copolymer (C1) and two or more of the aforementioned hydrogenated block copolymers (C2), it may be that the aforementioned hydrogenated block copolymer (C1) and one or more of the aforementioned hydrogenated block copolymers (C2) constitute the aforementioned (C-1) component, and one or more of the aforementioned hydrogenated block copolymers (C2) constitute the aforementioned (C-2) component.

[0108] <Softening agent (D)>

[0109] The content (%C P ) of alkane-based carbon atoms determined by ASTM D3238-85 or ASTM D2140 for the softening agent (D) used in the present invention is 80% or more and 100% or less. By using such a softening agent, the resulting thermoplastic elastomer composition has excellent fluidity, less hue unevenness, and excellent molding appearance.

[0110] From the viewpoint of more excellent fluidity and less hue unevenness of the resulting thermoplastic elastomer composition, the content (%C P ) is preferably 85% or more and 100% or less, more preferably 90% or more and 100% or less.

[0111] From the aforementioned viewpoints, the content (%C N ) of naphthene-based carbon atoms is preferably 0% or more and 20% or less, more preferably 0% or more and 10% or less, and further preferably 0% or more and 5% or less.

[0112] From the aforementioned viewpoints, the content (%C NA)Preferably not less than 0% and not more than 10%, more preferably not less than 0% and not more than 5%, and still more preferably not less than 0% and not more than 1%.

[0113] The aforementioned %C P , %C N and %C A can be obtained by the measurement method according to ASTM D 3238-85 or ASTM D2140. %C P , %C N and %C A respectively refer to the percentage of the number of alkane carbon atoms, the percentage of the number of naphthene carbon atoms, and the percentage of the number of aromatic carbon atoms in the total number of carbon atoms obtained by the aforementioned measurement method.

[0114] ASTM D 3238-85 relates to the standard test method (Standard Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method) for the calculation of carbon distribution and structural group analysis based on the n-d-M method, and stipulates the ring analysis (Ring Analysis) based on the n-d-M method. The ring analysis based on this n-d-M method is a kind of structural group analysis used in the composition analysis of high-boiling petroleum fractions, and is a method for obtaining the following carbon distribution and ring content from the measured values of the refractive index n, density d, and average molecular weight M of the sample at 20 °C or 70 °C by calculation formulas or charts.

[0115] · Carbon distribution

[0116] Aromatic carbon %: %C A

[0117] Naphthene carbon %: %C N

[0118] Alkane carbon %: %C P

[0119] Ring structure carbon %: %C R =%C A +%C N

[0120] · Ring content

[0121] Number of aromatic rings: R A

[0122] Number of naphthene rings: R N

[0123] On the other hand, ASTM D2140 relates to the Standard Practice for Calculating Carbon-Type Composition of Insulating Oils of Petroleum Origin. In ASTM D2140, the carbon-type composition of the softener (D) can be calculated using viscosity, density, and refractive index, and the percentage of aromatic carbon (%C A ), percentage of naphthenic carbon (%C N ), and percentage of paraffinic carbon (%C P ) can be obtained through ring analysis. In the present invention, even if the percentage of aromatic carbon (%C A ), percentage of naphthenic carbon (%C N ), and percentage of paraffinic carbon (%C P ) obtained in ASTM D2140 are used to replace the percentage of aromatic carbon (%C A ), percentage of naphthenic carbon (%C N ), and percentage of paraffinic carbon (%C P ) obtained in ASTM D3238-85, there is no practical problem.

[0124] From the perspective of weight reduction of the molded body, the density of the aforementioned softener (D) at 15°C is preferably 890 kg / m 3 or less, more preferably 865 kg / m 3 or less, and even more preferably 850 kg / m 3 or less. In addition, the density of the aforementioned softener (D) at 15°C is preferably 800 kg / m 3 or more, and more preferably 820 kg / m 3 or more.

[0125] It should be noted that the aforementioned density of the softener (D) is specifically the value measured at a predetermined measurement temperature (e.g., 15°C) according to the measurement method of ASTM D 4052.

[0126] From the perspective of fluidity, the kinematic viscosity of the aforementioned softener (D) at 40°C is preferably 40 mm 2 / s or more and 300 mm 2 / s or less, more preferably 40 mm 2 / s or more and 200 mm 2 / s or less, and even more preferably 40 mm 2 / s or more and 150 mm 2 / s or less. In addition, the kinematic viscosity of the softening agent (D) is a value measured at its measurement temperature (for example, 40 °C) according to the measurement method of ISO3104.

[0127] From the aspect of flexibility under low-temperature conditions, the pour point of the aforementioned softening agent (D) is preferably -10 °C or lower, more preferably -15 °C or lower, and still more preferably -20 °C or lower. In addition, the pour point of the softening agent (D) is usually -50 °C or higher, preferably -40 °C or higher, and more preferably -30 °C or higher. It should be noted that the pour point of the softening agent (D) is a value measured according to ASTM D-6749.

[0128] In addition, from the aspect of reducing volatile components (for example, making the atomization characteristics good), the evaporation loss of the aforementioned softening agent (D) at 200 °C, normal pressure, and 1 hour is preferably 0.2% by mass or less, more preferably 0.15% by mass or less, and still more preferably 0.13% by mass or less. The evaporation loss at 200 °C, normal pressure, and 3 hours is preferably 1.2% by mass or less, more preferably 1.0% by mass or less, and still more preferably 0.8% by mass or less. The evaporation loss at 200 °C, normal pressure, and 5 hours is preferably 2.5% by mass or less, more preferably 2.0% by mass or less, and still more preferably 1.5% by mass or less. By using a softening agent with an evaporation loss of a certain amount or less as the softening agent (D), the content of volatile components in the thermoplastic elastomer composition of the present invention becomes less and is satisfactory. For example, it has good atomization characteristics.

[0129] It should be noted that the aforementioned evaporation loss of the softening agent (D) is specifically a value measured by the method described in "(5-2) Heating evaporation loss" in the following examples.

[0130] Any softening agent can be used as the aforementioned softening agent (D) as long as it satisfies the above properties. For example, it can be a refined mineral oil, a synthetic oil obtained by polymerizing an olefin-based monomer, a biomass-derived softening agent described later, or a mixture of two or more of them.

[0131] Among these, the aforementioned softening agent (D) preferably contains a biomass-derived softening agent, and more preferably contains only a biomass-derived softening agent. By using a biomass-derived softening agent, the obtained thermoplastic elastomer composition not only has excellent fluidity, less hue unevenness, and excellent molding appearance, but also can reliably reduce the environmental load. In addition, the biomass-derived softening agent has a lower density at 15 °C than refined mineral oil and synthetic oil (for example, the density of the softening agent (D) is 865 kg / m 3 or less), which is also advantageous from the viewpoint of lightening the weight of the molded body.

[0132] The aforementioned softening agent derived from biomass is a softening agent obtained from raw materials such as cultivated plants, natural plants, and other plants, as well as animal fat sources. The softening agent (D) may contain not only softening agents derived from biomass but also softening agents derived from fossil fuels. However, from the perspective of better reducing the environmental load, the softening agent (D) preferably contains softening agents derived from biomass and does not contain softening agents derived from fossil fuels. It should be noted that a softening agent derived from fossil fuels refers to a softening agent obtained through a manufacturing process including processing and other procedures from fossil fuels such as natural gas.

[0133] The softening agent derived from biomass obtained from plant or animal fat sources is an organic compound or a mixture of organic compounds obtained from such raw materials through a manufacturing process including, for example, extraction or processing.

[0134] In most cases, the softening agent derived from biomass contains various specific organic compounds contained in raw materials such as plants (e.g., sugarcane, rapeseed) and animal fat sources (e.g., butter), and further contains these organic compounds in a specific composition distribution. Therefore, generally speaking, it is difficult for the softening agent derived from biomass and the softening agent derived from fossil fuels to have the same chemical composition.

[0135] Preferred plants as raw materials for the softening agent derived from biomass include, for example, trees, sunflowers, rapeseed, rapeseed, corn, flaxseed, jojoba, peanuts, coconuts, thistles, castor, soybeans, palm, hemp, olives, sugarcane, beets, and other grains.

[0136] Preferred animal fat sources as raw materials for the softening agent derived from biomass include, for example, butter, lard, tallow, beef fat, herring, sardines, and other animal fats.

[0137] As raw materials for the softening agent derived from biomass, plants are preferred, and cultivated plants are more preferred.

[0138] As a preferred form of raw materials for the softening agent derived from biomass, vegetable oils obtained from the above-mentioned cultivated plants and other plants are preferred. Preferred vegetable oils include, for example, lignin oil, sunflower oil, rapeseed oil, rapeseed oil, corn oil, hempseed oil, olive oil, linseed oil, soybean oil, palm oil, jojoba oil, etc.

[0139] In addition, as raw materials for the softening agent derived from biomass, raw materials obtained from the above-mentioned cultivated plants and other plants that may contain starch, cellulose, or lignin are another preferred form. Among them, as such raw materials, there are raw materials obtained from sugarcane or beets, raw materials obtained from palm oil, raw materials obtained from sunflowers, raw materials obtained from rapeseed, etc.

[0140] As a softening agent derived from biomass, it is preferably a plant-derived softening agent classified into the following (α) to (γ).

[0141] (α) A softening agent containing a fatty acid ester represented by the following formula (α)

[0142] (β) A softening agent containing a triglyceride represented by the following formula (β)

[0143] (γ) A softening agent containing a dimer acid-based compound, i.e., a dimer acid ester, represented by the following formula (γ)

[0144] The biomass-derived softening agent (α) of the above classification (α) is a softening agent containing a fatty acid ester represented by the following formula (α).

[0145] [Chemical formula 1]

[0146]

[0147] In the above formula (α), R1 is a substituted or unsubstituted aryl group having 1 to 22 carbon atoms, preferably a substituted or unsubstituted phenyl group having 1 to 10 carbon atoms; a substituted or unsubstituted linear or branched alkyl group having 1 to 22 carbon atoms; or a substituted or unsubstituted linear or branched alkylene group having 1 to 3 double bonds, preferably 1 double bond, and having 1 to 22 carbon atoms.

[0148] R2 is a substituted or unsubstituted linear or branched saturated or unsaturated aliphatic hydrocarbon group having 1 to 21 carbon atoms, preferably a linear saturated or unsaturated aliphatic hydrocarbon group having 1 to 21 carbon atoms, more preferably a linear unsaturated aliphatic hydrocarbon group having 1 to 21 carbon atoms and having 1 to 3 double bonds, and further preferably a linear unsaturated aliphatic hydrocarbon group having 1 double bond and having 1 to 17 carbon atoms.

[0149] When the above R1 is an alkyl group, it is preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, stearyl, oleyl, and more preferably 2-ethylhexyl, decyl or oleyl.

[0150] In addition, when the above R1 is an alkylene group having 1 double bond, the double bond is preferably located at the 9th position of the alkylene group.

[0151] In addition, unless otherwise specified, the number of carbon atoms of the groups that become the above R1 and R2 is the total number of carbon atoms including the carbon atoms of the substituents and side chains.

[0152] As R1 of the fatty acid ester represented by the above formula (α), a substituted or unsubstituted linear or branched alkyl group having 1 to 22 carbon atoms is preferred, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, stearyl, oleyl are more preferred, and 2-ethylhexyl, oleyl, decyl are further preferred.

[0153] As R2 of the fatty acid ester represented by the above formula (α), a substituted or unsubstituted linear or branched saturated or unsaturated aliphatic hydrocarbon group having 1 to 21 carbon atoms is preferred, a linear saturated or unsaturated aliphatic hydrocarbon group having 1 to 21 carbon atoms is more preferred, a linear unsaturated aliphatic hydrocarbon group having 1 to 21 carbon atoms and having 1 to 3 double bonds is further preferred, and a linear unsaturated aliphatic hydrocarbon group having 1 to 17 carbon atoms and having 1 double bond is still further preferred.

[0154] As preferred compounds of the fatty acid ester represented by the above formula (α), for example, alkyl arachidonate, alkyl linoleate, alkyl linolenate, alkyl laurate, alkyl myristate, alkyl oleate, alkyl caprate, alkyl stearate, alkyl palmitate, alkyl octanoate, alkyl hexanoate, alkyl butyrate, alkyl behenate, etc. can be cited.

[0155] Among these fatty acid esters, 2-ethylhexyl oleate, 2-ethylhexyl stearate, decyl oleate, decyl stearate, oleyl oleate, oleyl stearate are preferred.

[0156] The above fatty acid esters can be used alone or in the form of a mixture of two or more.

[0157] The biomass-derived softener (β) of the above classification (β) is a softener containing a triglyceride represented by the following formula (β). Triglyceride refers to an ester of glycerol in which all the hydroxyl groups of a fatty acid having 3 hydroxyl groups are esterified.

[0158] [Chemical formula 2]

[0159]

[0160] In the above formula (β), R3, R4 and R5 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 22 carbon atoms; or a substituted or unsubstituted linear or branched alkylene group having 1 to 3 double bonds, preferably 1 double bond, and having 1 to 22 carbon atoms.

[0161] As R3, R4 and R5 of the triglyceride represented by the above formula (β), it is preferred that they are all the same. One preferred form of R3, R4 and R5 of the triglyceride represented by the above formula (β) is oleyl, and another preferred form is an organic group having 17 carbon atoms represented by the following formula (β1).

[0162] [Chemical formula 3]

[0163]

[0164] The biomass-derived softener (γ) of the above classification (γ) is a softener containing a dimer acid-based compound shown by the following formula (γ), i.e., a dimer acid ester. This dimer acid ester is usually a reaction product of dimer acid and a linear or branched saturated alcohol having 1 to 22 carbon atoms or an unsaturated alcohol having 1 to 3 carbon-carbon double bonds.

[0165] [Chemical formula 4]

[0166]

[0167] In the above formula (γ), n is an integer of 1 or more, preferably an integer of 1 to 40, more preferably an integer of 1 to 30, and R6 and R7 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 22 carbon atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, stearyl, oleyl.

[0168] The dimer acid ester is an ester of an unsaturated fatty acid dimer. The dimer fatty acid is obtained by dimerization of each fatty acid. This ester can be obtained by the reaction of the above dimer acid and an alcohol. As the aforementioned alcohol used as a raw material for the dimer acid ester, methanol, 2-ethylhexanol, tridecanol, and oleyl alcohol are preferred.

[0169] When using the aforementioned biomass-derived softeners (α) to (γ) as the biomass-derived softener, one kind can be used alone as this softener, or a mixture of two or more kinds can be used as this softener.

[0170] From the viewpoints of suppressing the bleeding of the softener and achieving both good fluidity and reduced hue unevenness, the content of the softener (D) is 20 to 250 parts by mass, preferably 50 to 200 parts by mass, relative to 100 parts by mass of the aforementioned polypropylene-based resin (A).

[0171] <Composition of the thermoplastic elastomer composition>

[0172] The thermoplastic elastomer composition of the present invention contains the aforementioned polypropylene-based resin (A), the aforementioned ethylene-α-olefin copolymer (B), the aforementioned hydrogenated block copolymer (C), and the aforementioned softener (D), and at least a part thereof is crosslinked.

[0173] The thermoplastic elastomer composition of the present invention preferably satisfies the following requirements (1) to (3):

[0174] Requirement (1):

[0175] The melt flow rate (MFR, 230 °C, 1.2 kg load) of the thermoplastic elastomer composition of the present invention as measured according to ASTM D1238 is preferably 20 to 100 g / 10 minutes, more preferably 50 to 90 g / 10 minutes.

[0176] Requirement (2):

[0177] The surface hardness (Shore A hardness, instantaneous value) of the thermoplastic elastomer composition of the present invention as measured according to JIS K7215 is preferably 60 to 100, more preferably 60 to 80. Herein, the aforementioned surface hardness can be measured by the method described in the following examples.

[0178] Requirement (3):

[0179] The tensile elongation of the thermoplastic elastomer composition of the present invention as measured according to JIS K6251 is preferably 100% or more, more preferably 200% or more. The upper limit of the tensile elongation is not particularly limited as long as the effects of the present invention are not impaired, and is, for example, 600%.

[0180] The thermoplastic elastomer composition satisfying the aforementioned requirements (1) to (3) has the following properties: it is easy to perform molding processing typified by injection molding, has a good touch feeling, and has high durability.

[0181] In addition, the thermoplastic elastomer composition of the present invention preferably further satisfies the following requirement (4) in addition to satisfying the aforementioned requirements (1) to (3):

[0182] Requirement (4):

[0183] From the viewpoints of moldability, durability, and touch feeling, the viscosity of the thermoplastic elastomer composition of the present invention at a frequency of 1.216×10 measured at 230 °C, L = 30 mm, 3 1 / s according to JIS K7199 is preferably 10 to 25 Pa·s, more preferably 10 to 20 Pa·s.

[0184] The thermoplastic elastomer composition satisfying the aforementioned requirements (1) to (3), preferably satisfying the aforementioned requirements (1) to (4), can be produced as follows.

[0185] Regarding the aforementioned requirements (1) and (4), the MFR and viscosity of the thermoplastic elastomer composition can be adjusted, for example, by changing the addition amount of an organic peroxide, which is a crosslinking agent added when mixing a thermoplastic elastomer and a polypropylene-based resin as raw materials in an extruder. For example, there is a tendency that the MFR of the obtained thermoplastic elastomer composition becomes larger as the addition amount of the organic peroxide increases.

[0186] In addition, regarding the aforementioned 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 smaller the addition amount of the softening agent (D), the greater the surface hardness of the obtained thermoplastic elastomer composition tends to be.

[0187] In addition, regarding the aforementioned requirement (3), the tensile elongation at break of the thermoplastic elastomer composition can be adjusted by changing the composition of the thermoplastic elastomer composition. For example, the greater the proportion of the aforementioned hydrogenated block copolymer (C) relative to the aforementioned polypropylene-based resin (A), the greater the tensile elongation at break of the obtained thermoplastic elastomer composition tends to be.

[0188] In this way, by appropriately adjusting the addition amounts of the respective components contained in the thermoplastic elastomer composition and the composition of the thermoplastic elastomer composition, a thermoplastic elastomer composition satisfying the above (1) to (4) can be obtained.

[0189] The thermoplastic elastomer composition of the present invention may be composed only of the aforementioned polypropylene-based resin (A), the aforementioned ethylene-α-olefin copolymer (B), the aforementioned hydrogenated block copolymer (C), and the aforementioned softening agent (D) as long as at least a part thereof is crosslinked. In addition, the thermoplastic elastomer composition of the present invention may further contain other components (hereinafter referred to as "other components") that do not belong to these components (A) to (D) in addition to the aforementioned polypropylene-based resin (A), the aforementioned ethylene-α-olefin copolymer (B), the aforementioned hydrogenated block copolymer (C), and the aforementioned softening agent (D).

[0190] Crosslinking of the thermoplastic elastomer composition of the present invention is usually carried out in the presence of a crosslinking agent. Therefore, in a preferred embodiment of the thermoplastic elastomer composition of the present invention, the thermoplastic elastomer composition further contains a crosslinking agent described later. At this time, the thermoplastic elastomer composition may further contain a crosslinking aid described later.

[0191] <Crosslinking agent>

[0192] As described above, the thermoplastic elastomer composition of the present invention may further contain a crosslinking agent. Examples of the aforementioned crosslinking agent include commonly used crosslinking agents such as organic peroxides, phenolic resins, sulfur, hydrogenated organosilicon compounds, amino resins, quinones or their derivatives, amine compounds, azo compounds, epoxy compounds, isocyanates, and thermosetting elastomers. Among them, the crosslinking agent is preferably an organic peroxide. This organic peroxide can promote the decomposition reaction of the aforementioned polypropylene-based resin (A) during crosslinking. As a result, the fluidity and moldability of the thermoplastic elastomer composition can be further improved, and even when manufacturing a part with a large surface area and a complex shape, the followability to a mold or the like is good, and the composition can be filled into the mold more completely without gaps.

[0193] Specific examples of the aforementioned organic peroxides include: 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, 1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-hexylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)cyclododecane, 1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)octane, n-butyl-4,4-bis(tert-butylperoxy)butane, n-butyl-4,4-bis(tert-butylperoxy)valerate and other ketone peroxides; di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, α,α'-bis(tert-butylperoxy)m-isopropylbenzene, α,α'-bis(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hex-3-yne and other dialkyl peroxides; acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-trioyl peroxide and other diacyl peroxides; tert-butyl peracetate, tert-butyl perisobutyrate, tert-butyl per-2-ethylhexanoate, tert-butyl perlaurate, tert-butyl perbenzoate, di-tert-butyl m-phthalate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, tert-butyl permaleate, tert-butyl perisopropyl carbonate, cumyl octanoate peroxide and other peroxide esters; tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl peroxide and other hydroperoxides, etc.

[0194] Among the above-mentioned organic peroxides, from the viewpoints of thermal decomposition temperature and crosslinking performance, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hex-3-yne are preferred. In a preferred embodiment of the present invention, the aforementioned crosslinking agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0195] When the thermoplastic elastomer composition of the present invention contains a crosslinking agent, from the viewpoint of molding fluidity, preferably 2 parts by mass or more, more preferably 6 parts by mass or less, and still more preferably 4 parts by mass or less are contained relative to 100 parts by mass of the aforementioned propylene-based resin (A).

[0196] When an organic peroxide is contained as a crosslinking agent in the thermoplastic elastomer composition of the present invention, from the viewpoint of molding fluidity, the 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 aforementioned polypropylene-based resin (A).

[0197] <Crosslinking aid>

[0198] In the present invention, a crosslinking aid can be incorporated when crosslinking treatment is carried out using the above-mentioned organic peroxide. That is, when the thermoplastic elastomer composition of the present invention contains the aforementioned organic peroxide as the aforementioned crosslinking agent, the thermoplastic elastomer composition can further contain a crosslinking aid. For the crosslinking aid that can be used in the present invention, from the aspect of being able to control the crosslinking reaction rate, a monofunctional monomer or a polyfunctional monomer is preferred.

[0199] As the above-mentioned monofunctional monomer, for example, a radically polymerizable vinyl-based monomer is preferred, and examples include aromatic vinyl monomers, unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile, acrylate monomers, methacrylate monomers, acrylic acid monomers, methacrylic acid monomers, maleic anhydride monomers, N-substituted maleimide monomers, etc.

[0200] Specific examples of the monofunctional monomer include, for example: styrene, methylstyrene, chloromethylstyrene, hydroxystyrene, tert-butoxystyrene, acetoxystyrene, chlorostyrene, acrylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, maleic anhydride, methylmaleic anhydride, 1,2-dimethylmaleic anhydride, ethylmaleic anhydride, phenylmaleic anhydride, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-laurylmaleimide, N-cetylmaleimide, etc. Among them, from the viewpoints of ease of reaction and versatility, styrene, acrylonitrile, methacrylonitrile, methyl acrylate, maleic anhydride, N-methylmaleimide, etc. are preferred. These monofunctional monomers can be used alone or in combination of two or more.

[0201] 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 of the polyfunctional monomer is preferably 2 or 3.

[0202] As specific examples of the polyfunctional monomer, 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-benzoquinone dioxime, p,p'-dibenzoylquinone dioxime, phenyl maleimide, allyl methacrylate, N,N'-m-phenylene bismaleimide, diallyl phthalate, tetraallyloxyethane, 1,2-polybutadiene, etc. are preferred, and divinylbenzene and triallyl isocyanurate are more preferred. These polyfunctional monomers can be used alone or in combination of two or more.

[0203] From the viewpoint of molding fluidity, the above crosslinking aids are preferably used in an amount of preferably 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass, based on 100 parts by mass of the aforementioned polypropylene resin (A).

[0204] Within the scope not impairing the object of the present invention, the thermoplastic elastomer composition of the present invention may contain, in addition to the crosslinking agent and the crosslinking aid, for example, lubricants (such as polyorganosiloxanes), inorganic fillers, plasticizers, and other additives as the above other components.

[0205] <Lubricant>

[0206] The thermoplastic elastomer composition of the present invention may contain a lubricant. As the lubricant, for example, polyorganosiloxanes, fluororesins, fatty acid metal salts, aliphatic amides, etc. can be cited. Among these lubricants, polyorganosiloxanes are preferred from the viewpoint of abrasion resistance.

[0207] <Polyorganosiloxane>

[0208] As a lubricant of the thermoplastic elastomer composition of the present invention, containing polyorganosiloxane is a preferred embodiment. As the structure of the polyorganosiloxane, there is no particular limitation, and a polymer structure of a linear, branched or crosslinked structure is preferably adopted from the viewpoints of abrasion resistance and touch feeling.

[0209] The polyorganosiloxane is not particularly limited, and known substances can also be used. As the preferred polyorganosiloxane, it is a polymer containing siloxane units having substituents such as alkyl, vinyl, aryl, etc., and among them, polyorganosiloxane having an alkyl group is particularly preferred, and polyorganosiloxane having a methyl group is more preferred.

[0210] As specific examples of the polyorganosiloxane having a methyl group, for example, polydimethylsiloxane, polymethylphenylsiloxane, polymethylhydrosiloxane, etc. can be cited. Among them, polydimethylsiloxane is preferred.

[0211] The kinematic viscosity of the polyorganosiloxane is not particularly limited. From the viewpoint of abrasion resistance, the kinematic viscosity (25 °C) specified in JIS Z8803 is preferably 5000 centistokes (cSt) or more. Further, from the viewpoints that the dispersibility of the polyorganosiloxane in the thermoplastic elastomer composition 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 is preferably less than 2 million cSt. The kinematic viscosity of the polyorganosiloxane is more preferably 10,000 cSt or more and less than 2 million cSt, and still more preferably 50,000 cSt or more and less than 2 million cSt.

[0212] In addition, the polyorganosiloxane may be added to the thermoplastic elastomer composition in the form of a masterbatch obtained by mixing the polyorganosiloxane and the thermoplastic resin.

[0213] From the viewpoints of suppressing bleeding during molding and ensuring good abrasion resistance, the addition amount of the polyorganosiloxane is usually 5 to 20 parts by mass, preferably 8 to 15 parts by mass, based on 100 parts by mass of the aforementioned polypropylene resin (A).

[0214] Examples of the inorganic filler include calcium carbonate, magnesium carbonate, silica, carbon black, glass fiber, titanium oxide, clay, mica, talc, magnesium hydroxide, aluminum hydroxide, etc.

[0215] Examples of the plasticizer include polyethylene glycol, phthalic acid esters such as dioctyl phthalate (DOP), etc.

[0216] Examples of other additives include: organic / inorganic pigments such as carbon black, titanium oxide or phthalocyanine black; heat stabilizers such as 2,6-di-tert-butyl-4-methylphenol, n-octadecyl 3-(3,5'-di-tert-butyl-4-hydroxyphenyl) propionate; antioxidants such as tris(nonylphenyl) phosphite, distearyl pentaerythritol diphosphite; ultraviolet absorbers such as 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, 2,4-dihydroxybenzophenone; light stabilizers such as bis-[2,2,6,6-tetramethyl-4-piperidyl] sebacate, tetra(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate; flame retardants such as ammonium polyphosphate, tributyl phosphate and magnesium hydroxide; silicone oils such as dimethyl silicone oil, methylphenyl silicone oil; anti-blocking agents such as stearic acid amide, erucic acid amide; blowing agents such as sodium bicarbonate, N,N'-dinitrosopentamethylenetetramine; antistatic agents such as monoglyceryl palmitate, monoglyceryl stearate; antibacterial agents such as silver ion-supported zeolite, silver thiosulfite complex, etc.

[0217] <Method for producing thermoplastic elastomer composition>

[0218] The thermoplastic elastomer composition of the present invention can be obtained by crosslinking a mixture containing the aforementioned polypropylene-based resin (A), the aforementioned ethylene-α-olefin copolymer (B), the aforementioned hydrogenated block copolymer (C), and the aforementioned softener (D). The method for performing the aforementioned crosslinking is not particularly limited and can be a known method. Here, the aforementioned crosslinking is preferably performed in the presence of the aforementioned crosslinking agent. The conditions for the crosslinking reaction are not particularly limited, and appropriate conditions can be suitably adopted according to the desired physical properties of the thermoplastic elastomer composition of the present invention and the like.

[0219] The thermoplastic elastomer composition of the present invention can be manufactured by a usual method using a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, etc. that are used in the manufacture of ordinary elastomer compositions. Among them, from the viewpoint of effectively achieving the dynamic crosslinking of the thermoplastic elastomer, a method of manufacturing using a twin-screw extruder is preferred. In the case of using a twin-screw extruder, for example, by adding the aforementioned polypropylene-based resin (A) and the aforementioned crosslinking agent, etc., to make them uniformly and finely dispersed, and further adding other components, the crosslinking reaction of the composition can occur, and the thermoplastic elastomer composition can be continuously manufactured.

[0220] In addition, in the manufacture of the above-mentioned thermoplastic elastomer composition, it is also preferably manufactured via the following processing steps. That is, the aforementioned polypropylene-based resin (A), the aforementioned ethylene-α-olefin copolymer (B), and the aforementioned polyorganosiloxane added as needed are fully mixed and put into the hopper of the extruder. At this time, the aforementioned crosslinking agent can be added to the extruder from the beginning together with the aforementioned polypropylene-based resin (A) and the aforementioned ethylene-α-olefin copolymer (B), or a part of the aforementioned crosslinking agent can be added from the middle of the extruder. Furthermore, a part of the aforementioned polypropylene-based resin (A) and the aforementioned ethylene-α-olefin copolymer (B), etc. can also be added from the middle of the extruder. In addition, the aforementioned hydrogenated block copolymer (C) can be added from the middle of the extruder or can be divided into adding at the beginning and in the middle. At this time, the aforementioned crosslinking agent can also be premixed with the aforementioned hydrogenated block copolymer (C) and added. The addition method of the aforementioned softener (D) can be any of adding at the beginning, dividing into adding at the beginning and in the middle, and only adding in the middle. The addition method of the aforementioned softener (D) can be a method of adding a masterbatch containing the aforementioned softener (D) at a high concentration in advance using any thermoplastic resin or elastomer.

[0221] When heated and melted and kneaded in the extruder, the aforementioned polypropylene-based resin (A) is further promoted to decompose by the aforementioned crosslinking agent, and has the effect of improving the molding fluidity. Furthermore, by adding the aforementioned hydrogenated block copolymer (C), etc. and performing melt kneading, after sufficient crosslinking reaction, kneading / dispersion, it is taken out from the extruder, and thus pellets of the thermoplastic elastomer composition can be obtained.

[0222] Molded article

[0223] The molded article obtained in the present invention contains the thermoplastic elastomer composition of the present invention described above. The aforementioned molded article may be a film or a sheet. As the use of the aforementioned molded article, interior materials for automobiles can be cited.

[0224] Such a molded article can be obtained by molding the aforementioned thermoplastic elastomer composition using various molding methods. Examples of the aforementioned molding methods include injection molding, extrusion molding, vacuum molding, pressure-air molding, blow molding, calendering, foam molding, etc. For example, by filling the above-mentioned thermoplastic elastomer composition heated and melted into a mold for molding, demolding is performed after cooling and solidifying, whereby a molded article (molded product) such as a skin material can be obtained.

[0225] The thermoplastic elastomer composition of the present invention is preferably made into an injection molded article (injection molded product). When made into an injection molded article, the productivity is excellent. The shape of the injection molded article is not particularly limited, and from the viewpoint of its use as a skin material, a film or a sheet is preferred.

[0226] The above injection molded article can be used for various members. In particular, from the viewpoint of being able to inject-mold a thin-walled molded article (thin-walled molded product) with a complex shape with good reproducibility, it is preferably used as an interior material for automobiles such as an instrument panel. Among interior materials for automobiles, an instrument panel usually has a complex shape as follows: not only thin-walled but also having a large surface area, and having a texture pattern on the surface, or having an opening in a part, or having not only a flat part but also a curved part, or being a three-dimensional structure, or having not only a thin-walled part but also a thick-walled part. According to the present embodiment, a thin-walled and large-surface-area injection molded article can be produced, so it is suitable as an instrument panel or its member.

[0227] The shape and constitution of the interior material for automobiles are not particularly limited, and can be appropriately made into a suitable constitution according to the use, etc. As a preferred example, a laminate having a layer containing the interior material for automobiles of the present embodiment (hereinafter sometimes referred to as "skin material layer") and a layer containing a core material laminated on the layer containing the aforementioned interior material for automobiles (hereinafter sometimes referred to as "core material layer") can be cited. By providing a laminate having not only a skin material layer but also a core material layer, even a three-dimensional complex shape can be stably mass-produced, so that an improvement in production efficiency and a reduction in cost can be achieved.

[0228] The material used as the core material is not particularly limited, and known materials can be used. Examples include polypropylene, acrylonitrile-butadiene-styrene (ABS) resin, polycarbonate / acrylonitrile-butadiene-styrene alloy (PC / ABS alloy), acrylonitrile-styrene copolymer, modified polyphenylene ether, etc. Resins with improved strength can be obtained by mixing fillers such as talc and glass fiber into them as needed. Among them, it is preferable to contain 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, from the perspective of light weight, polypropylene is more preferable.

[0229] The layer structure of the laminate of the present embodiment is not particularly limited, as long as it has a structure of two or more layers including at least a skin material layer and a core material layer. In the present embodiment, the skin material layer and the core material layer do not have to be in contact, and other layers may exist between the skin material layer and the core material layer.

[0230] The thickness of the skin material layer is not particularly limited, preferably 0.5 to 2.0 mm, more preferably 0.8 to 1.5 mm. By setting the thickness of the skin material layer to 0.5 mm or more, the appearance, chemical resistance, and abrasion resistance can be made more excellent. By setting it to 2.0 mm or less, the economy and touch can also be made more excellent. In the prior art, it is difficult to efficiently manufacture such a thin-walled skin material layer, but by using the thermoplastic elastomer composition of the present embodiment, such a thin-walled skin material layer can also be easily manufactured.

[0231] The thickness of the core material layer is not particularly limited, preferably 2.0 to 4.5 mm, more preferably 2.5 to 3.5 mm. By setting the thickness of the core material layer to 2.0 mm or more, the rigidity, heat resistance, and moldability can be made more excellent. By setting it to 4.5 mm or less, the economy and light weight can also be made more excellent.

[0232] Furthermore, the laminate of the present embodiment preferably further includes a layer containing a foaming material between the skin material layer and the core material layer. The foaming material more preferably contains a thermosetting polyurethane foam with a density of 100 to 250 kg / m 3 ³. By setting the density of the foaming material to 100 kg / m 3 ³ or more, indentations are less likely to occur during manufacturing and handling during removal, and the operability can be made more excellent. By setting the density of the foaming material to 250 kg / m 3 ³ or less, an appropriate softness can be imparted to the laminate. From this perspective, the density of the foaming material is further preferably 120 to 180 kg / m 3 ³.

[0233] The type of the thermosetting polyurethane foam is not particularly limited, and a semi-rigid thermosetting polyurethane foam is preferred. The semi-rigid thermosetting polyurethane foam refers to a polyurethane foam having an open-cell structure of 90% or more.

[0234] The method for manufacturing the laminate is not particularly limited, and a known method can also be adopted. For example, the following methods can be cited: a method of forming a skin material, a core material, and a foaming material separately, and then laminating the above components using an adhesive such as a chloroprene-based adhesive to form a laminated structure; a method of forming a core material in advance, disposing the core material in a mold, and integrally molding it with the molding of the skin material (integral molding) to laminate the core material and two components to form a laminated structure.

[0235] By adopting the above laminated structure, a skin material with uniform plate thickness, good texture reproducibility, good touch, and good appearance can be obtained, and a three-dimensional complex-shaped laminate can also be stably mass-produced. Furthermore, by adopting a laminated structure of three or more layers including the above foaming material, a laminate that further effectively utilizes the soft touch of the skin material can be obtained.

[0236] In automotive interior components, the above laminate can be suitably used as instrument panels, door panels, glove box lids, etc. with thin walls and large surface areas that are difficult to manufacture by injection molding in the past, and is particularly suitable for use as an instrument panel.

[0237] The instrument panel according to the present embodiment can achieve the effects described in the embodiments of the automotive skin material and the laminate. In addition, since the skin material has good elongation characteristics at low temperatures, it is easier to ensure the deployment performance of the co-pilot airbag at low temperatures, etc. For example, it is also possible to maintain and improve the design freedom such as making the skin material of the airbag deployment part seamless.

[0238] Examples

[0239] Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. It should be noted that the physical properties in the examples are measured as follows.

[0240] [Measurement method]

[0241] (1) Shear viscosity

[0242] The shear viscosity (Pa·sec) is measured according to JIS K7199 at 230 °C, L = 30 mm, under the following conditions.

[0243] (2) Surface hardness (Shore A hardness)

[0244] As the surface hardness, the Shore A hardness (also referred to as "JIS-A hardness") was measured. Here, regarding the measurement of the Shore A hardness, four 2-mm thick sheets as samples were stacked, and evaluation was carried out in a 23°C atmosphere according to JIS K7215 using Type A. The hardness at the instant when the probe of the hardness tester was lowered onto the sample was taken as the surface hardness (instantaneous value), and the hardness 10 seconds after the lowering was taken as the surface hardness (after 10 s) for measurement.

[0245] (3) Appearance evaluation

[0246] The molded product with patterns obtained by injection molding was left standing in a Geer oven at 120°C for 500 hours, and the appearance of the patterned surface 1 hour after removal was evaluated. The evaluation criteria are as follows.

[0247] 3 ··· No hue unevenness was observed.

[0248] 2 ··· Hue unevenness was confirmed in a part of the molded product.

[0249] 1 ··· Hue unevenness was confirmed in the whole molded product.

[0250] (4) Physical properties of the hydrogenated block copolymer (C) and the corresponding pre-hydrogenated copolymer

[0251] (4-1) Hydrogenation rate

[0252] The hydrogenation rate of the hydrogenated block copolymer (C) was measured by nuclear magnetic resonance spectroscopy (NMR). A nuclear magnetic resonance measuring device (manufactured by JEOL Ltd., device name "JNM-LA400") was used as the measuring equipment, deuterated chloroform was used as the solvent, and tetramethylsilane (TMS) was used as the chemical shift reference. The measurement was carried out under the conditions of a sample concentration of 50 mg / mL, an observation frequency of 400 MHz, a pulse delay of 2.904 seconds, a scan number of 64 times, a pulse width of 45°, and a measurement temperature of 26°C.

[0253] (4-2) Contents of monomer units and bonding units

[0254] The contents of vinyl aromatic monomer units, ethylene monomer units, butene monomer units, 1,4-bonded units, 1,2-bonded units, and 3,4-bonded units of butadiene contained in the hydrogenated block copolymer (C) and the corresponding pre-hydrogenated copolymer were measured by NMR. A nuclear magnetic resonance measuring device (manufactured by JEOL Ltd., device name "JNM-LA400") was used as the measuring equipment, deuterated chloroform was used as the solvent, and tetramethylsilane (TMS) was used as the chemical shift reference. The measurement was carried out under the conditions of a sample concentration of 50 mg / mL, an observation frequency of 400 MHz, a pulse delay of 2.904 seconds, a scan number of 64 times, a pulse width of 45°, and a measurement temperature of 26°C.

[0255] The mass fraction (mass %) of each structural unit contained in the ethylene-α-olefin copolymer (B) is determined based on 13 the measured values of C-NMR. Specifically, using an ECX400P type nuclear magnetic resonance apparatus (manufactured by JEOL Ltd.), at a measurement temperature of 120 °C, a measurement solvent of ortho-dichlorobenzene / deuterated benzene = 4 / 1 (volume ratio), and a cumulative number of times of 8000 times, it is calculated from the 13 C-NMR spectrum of the copolymer (A-1).

[0256] (4-3) Styrene polymer block content (Os value)

[0257] Regarding the styrene polymer block content, the corresponding pre-hydrogenated copolymer is used, and the method described by I.M. Kolthoff et al., J. Polym. Sci. 1, 429 (1946) (osmium tetroxide decomposition method) is used for measurement. For the decomposition of the pre-hydrogenated copolymer, a 0.1 g / 125 mL tert-butanol solution of osmium acid is used. The styrene polymer block content is calculated by the following formula. The styrene polymer block content obtained here is referred to as the "Os value".

[0258] Styrene polymer block content (Os value; mass %)

[0259] = [(mass of styrene polymer block in the pre-hydrogenated copolymer) / (mass of the pre-hydrogenated copolymer)] × 100

[0260] (4-4) Molecular weight distribution

[0261] For the hydrogenated block copolymer (C), gel permeation chromatography (GPC) measurement is carried out under the following conditions to obtain the polystyrene-equivalent weight-average molecular weight Mw, number-average molecular weight Mn, and Mw / Mn.

[0262] Measuring model: manufactured by Shimadzu Corporation, LC-10

[0263] Column: TSKgel GMHXL (4.6 mm ID × 30 cm) 2 columns

[0264] Solvent: tetrahydrofuran

[0265] Temperature: oven temperature 40 °C

[0266] Concentration: 0.1%

[0267] Flow rate: 1.0 mL / minute

[0268] Detector: differential refractometer (RI)

[0269] Column correction: Monodisperse polystyrene (manufactured by Tosoh Corporation); #3 std set

[0270] Molecular weight conversion: Polystyrene conversion / Standard conversion method

[0271] (4 - 5) Loss tangent (tanδ peak temperature)

[0272] The loss tangent (tanδ peak temperature) is obtained by measuring the viscoelastic spectrum using a viscoelasticity measurement and analysis device (ARES, manufactured by TA Instruments). The measurement is carried out under the conditions of a strain of 0.1% and a frequency of 1 Hz.

[0273] In the examples and comparative examples, the following polymers were used.

[0274] (5) Physical properties of the softener

[0275] (5 - 1) Kinematic viscosity

[0276] The kinematic viscosity of the softener is measured at 40 °C and 100 °C respectively according to the measurement method of ISO3104.

[0277] (5 - 2) Heating evaporation loss

[0278] Weigh the softener as a sample and measure the weight (mass) before heating (W0). Then, heat this softener using an oven (Gill type oven: manufactured by Toyo Seiki Seisakusho Co., Ltd., ACR - 60), and measure the weight (mass) after cooling at room temperature for 1 hour (W1). Calculate the difference (W0 - W1) between the weight (mass) before heating (W0) and the weight after the aforementioned heating (W1) respectively, and take the percentage of the aforementioned difference (W0 - W1) relative to the weight (mass) before heating (W0) as the heating evaporation loss. In addition, the aforementioned heating is carried out under the conditions of "200 °C × 1 hour, in air".

[0279] (5 - 3) Pour point

[0280] The pour point of the softener is measured according to ASTM D - 6749.

[0281] (5 - 4) Hydrocarbon structure

[0282] For the softener, measure the content of naphthenic carbon atoms (%C N )(proportion of naphthenic carbon atoms), the content of paraffinic carbon atoms (%C P )(proportion of paraffinic carbon atoms), and the content of aromatic carbon atoms (%C A )(proportion of aromatic carbon atoms) according to ASTM D2140.

[0283] It should be noted that in the following Examples and Comparative Examples, the proportions of naphthenic carbon atoms, paraffinic carbon atoms, and aromatic carbon atoms were determined in accordance with ASTM D2140. However, they can also be determined in accordance with ASTM D3238 - 85 instead.

[0284] (5 - 5) Number - average molecular weight, weight - average molecular weight, molecular weight distribution

[0285] For the softener, gel permeation chromatography (GPC) was carried out under the following conditions to obtain the relative molecular weight (polystyrene - equivalent molecular weight) and its weight fraction (dW / dlogM) at each elution time, prepare a molecular weight distribution curve, and obtain the weight - average molecular weight Mw, number - average molecular weight Mn, and Mw / Mn in terms of polystyrene conversion.

[0286] Measuring model: manufactured by (Tosoh) Corporation, (gel permeation chromatograph HLC - 8321GPC)

[0287] Column: (2×TSKgel GMH6 - HT+2×TSKgel GMH6 - HTL (both 7.5mm I.D.×30cm, manufactured by Tosoh Corporation))

[0288] Solvent: o - dichlorobenzene; ODCB (containing 0.025% BHT)

[0289] Column temperature: 140 °C

[0290] Concentration: 0.1%

[0291] Flow rate: 1.0 mL / minute

[0292] Detector: differential refractometer (RI)

[0293] Column calibration: monodisperse polystyrene (manufactured by Tosoh Corporation); #3std set

[0294] Molecular weight conversion: polystyrene conversion / standard conversion method

[0295] [Raw materials]

[0296] In the Examples and Comparative Examples, the following components were used as the components constituting the composition.

[0297] <(A) Polypropylene - based resin>

[0298] As component (A), a homopolymer - type polypropylene manufactured by SunAllomer was used (melt flow rate (MFR) under the conditions of 230 °C and 2.16 kg load: 0.5 g / 10 minutes; weight - average molecular weight is 6.6×10 5 )(hereinafter referred to as "A - 1").

[0299] <(B) Ethylene-α-olefin copolymer>

[0300] As the component (B), a copolymer of ethylene and 1-octene (manufactured by Dow Chemical Company, trade name “ENGAGE8842”) is used. The content of ethylene in this copolymer is 55% by mass, and the content of 1-octene is 45% by mass. (Hereinafter, referred to as “B-1”).

[0301] <(C) Hydrogenated block copolymer>

[0302] As the hydrogenated block copolymer (C) (referred to as component (C)), the following hydrides (C1) and (C2) are used.

[0303] (C1) A hydride of a copolymer having a copolymer block and a vinyl aromatic monomer unit block, wherein the copolymer block contains a conjugated diene monomer unit as a main component and also contains a vinyl aromatic monomer unit.

[0304] Production of hydride (C1-1)

[0305] As the hydride (C1) of a copolymer having a copolymer block containing a conjugated diene monomer unit as a main component and also containing a vinyl aromatic monomer unit, and a vinyl aromatic monomer unit block, it is prepared as follows: A hydride (C1-1) of a copolymer having a copolymer block containing a conjugated diene monomer unit as a main component and also containing a vinyl aromatic monomer unit, and a vinyl aromatic monomer unit block (hereinafter referred to as “hydride (C1-1)”).

[0306] (1) Preparation of hydrogenation catalyst

[0307] The hydrogenation catalyst used in the hydrogenation reaction of the block copolymer is prepared by the following method.

[0308] 1 L of dried and refined cyclohexane is added to a reaction vessel after purging with nitrogen, 100 mmol of bis(cyclopentadienyl)titanium dichloride is added, and a hexane solution containing 200 mmol of trimethylaluminum is added while stirring thoroughly, and the reaction is carried out at room temperature for about 3 days.

[0309] (2) Production of block copolymer

[0310] Batch polymerization was carried out using a stirring device with an internal volume of 10 L and a jacketed tank reactor. First, 6.4 L of cyclohexane and 75 g of styrene were added. TMEDA was pre-added to be 0.25 times the molar amount of Li in n-butyllithium, and the n-butyllithium initiator was added in such a way that the molar amount of Li became 10 mmol. The first polymerization reaction was carried out at an initial temperature of 65 °C. After the completion of the first polymerization reaction, a cyclohexane solution containing 470 g of butadiene and 380 g of styrene (monomer concentration 22% by mass) was continuously supplied to the reactor at a constant rate over 60 minutes to carry out the second polymerization reaction. After the completion of the second polymerization reaction, a cyclohexane solution containing 75 g of styrene (monomer concentration 22% by mass) was further added over 10 minutes to carry out the third polymerization reaction. Then, methanol was added to terminate the third polymerization reaction, thereby obtaining 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%.

[0311] Next, the obtained copolymer (block copolymer) was subjected to the hydrogenation reaction described in (3) below.

[0312] (3) Production of hydride of block copolymer

[0313] To the block copolymer obtained in (2) above, the hydrogenation catalyst obtained in (1) above was added at 100 ppm in terms of titanium based on 100 parts by mass of the block copolymer, and the hydrogenation reaction of the block copolymer was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 75 °C. To the polymer solution containing the hydride of the block copolymer obtained in the above hydrogenation reaction, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was added at 0.3 parts by mass based on 100 parts by mass of the hydride of the block copolymer as a stabilizer.

[0314] The weight-average molecular weight of the obtained hydride of the block copolymer (C1-1) was 160,000, and the hydrogenation rate of the double bonds of butadiene contained in the hydride of the block copolymer (C1-1) was 99%. In addition, one of the tanδ peaks obtained by viscoelasticity measurement was present at -15 °C.

[0315] <(D) Softener, etc.>

[0316] As the softener (D) (referred to as component (D)), a paraffinic oil having the physical properties described in Table 1 below (hereinafter referred to as "D-1") was used.

[0317] In addition, as other softeners that do not belong to component (D) (hereinafter referred to as "component (D')"), paraffinic oils are used; D'-1 (manufactured by Idemitsu Kosan Co., Ltd., trade name "Diana Process Oil PW-100") and paraffinic oil; D'-2 (manufactured by Hansen & Rosenthal, trade name "Pionier 2275").

[0318] The physical properties of the aforementioned D-1, D'-1, and D'-2 are shown in Table 1 below.

[0319] [Table 1]

[0320]

[0321] <(E) Polyorganosiloxane>

[0322] 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)) (hereinafter referred to as "E-1") is used.

[0323] <Crosslinking agent and crosslinking aid>

[0324] Regarding the crosslinking agent, it is used in the form of a crosslinking agent mixture by mixing with the following crosslinking aid and the following softener. Here, as this crosslinking agent, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (manufactured by NOF Corporation, trade name "PERHEXA 25B") is used.

[0325] In addition, the crosslinking aid (polyfunctional monomer) and softener incorporated in the aforementioned crosslinking agent are as follows. Here, the amounts of the following crosslinking aid and softener are based on 100 parts by mass of the aforementioned crosslinking agent.

[0326] Crosslinking aid 1 (triallyl isocyanurate (manufactured by Nippon Kayaku Co., Ltd.; hereinafter referred to as "TAIC")) 35 parts by mass.

[0327] Crosslinking aid 2 (divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.; hereinafter referred to as "DVB")) 17 parts by mass.

[0328] Softener (manufactured by Idemitsu Kosan Co., Ltd., trade name "Diana Process Oil PW-100") 143 parts by mass

[0329] [Example 1 and Comparative Example 1]

[0330] As the extruder, a twin-screw extruder having an oil inlet at the central part of the barrel is used ( L / D = 47; manufactured by Toshiba Machine Co., Ltd., "TEM58SS"). As the screw, a double-threaded screw having a kneading section before and after the injection port is used.

[0331] After mixing the raw materials other than the softeners (component (D) and other softeners (component (D'))) described in Table 2 below in the composition ratios (parts by mass) described in Table 2 below, they are introduced into a twin-screw extruder (barrel temperature: 200 °C) using a metering feeder. Then, a predetermined amount of softener is injected from the injection port located at the central part of the twin-screw extruder using a pump, and melt extrusion is performed to obtain a thermoplastic elastomer composition. This thermoplastic elastomer composition is used as a sample for evaluation in the physical property evaluation of the aforementioned "(1) Shear viscosity".

[0332] Using a hot press (manufactured by Toho Press Mfg. Co., Ltd., "T-50"), the obtained thermoplastic elastomer composition is compression-molded at 200 °C to produce a 2-mm-thick sheet. The obtained 2-mm-thick sheet is used as a sample for evaluation in the physical property evaluation of the aforementioned "(2) Surface hardness (Shore A hardness)".

[0333] Next, using an injection molding machine "manufactured by Meiki Seisakusho Co., Ltd.; M150CL-DM", injection molding is performed on the obtained thermoplastic elastomer under the conditions of a resin temperature of 250 °C and a mold temperature of 40 °C. At this time, a flat mold with a size of 15 cm in length × 9 cm in width × 1 mm in thickness and having a grained finish is used to obtain a molded product having a roughness with an average arithmetic roughness Ra = 20 μm. The obtained molded product is used as a sample for evaluation in the evaluation of "(3) Molding appearance".

[0334] The results of the raw material formulation and the physical property evaluation are shown in Table 2 below.

[0335] [Table 2]

[0336]

Claims

1. A thermoplastic elastomer composition, which contains the following components (A) to (D) and is at least partially crosslinked, (A) 100 parts by mass of a polypropylene resin; (B) 40 to 80 parts by mass of an ethylene-α-olefin copolymer, which contains 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 a conjugated diene monomer unit and at least one block (c2) mainly composed of a vinyl aromatic monomer unit; (D) 20 to 250 parts by mass of a softening agent, the content of alkane-based carbon atoms measured according to ASTM D3238-85 or ASTM D2140, i.e., %C P is 80% or more and 100% or less.

2. The thermoplastic elastomer composition according to claim 1, wherein The softening agent (D) contains a biomass-derived softening agent.

3. The thermoplastic elastomer composition according to claim 1, wherein The softening agent (D) is a biomass-derived softening agent.

4. The thermoplastic elastomer composition according to claim 1, wherein The kinematic viscosity of the softening agent (D) at 40 °C is 40 mm 2 / s or more and 150 mm 2 / s or less.

5. The thermoplastic elastomer composition according to claim 1, wherein, The softening agent (D) has a density of 865 kg / m at 15 °C 3 as follows.

6. The thermoplastic elastomer composition according to claim 1, wherein The softening agent (D) has a pour point of -10°C or lower.

7. The thermoplastic elastomer composition according to claim 1, wherein The polypropylene resin (A) is at least one selected from the group consisting 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.

8. The thermoplastic elastomer composition according to claim 1, wherein, The polypropylene resin (A) consists only of a propylene homopolymer.

9. The thermoplastic elastomer composition according to claim 1, which further contains a lubricant.

10. The thermoplastic elastomer composition according to claim 9, wherein, The lubricant contains a polyorganosiloxane.

11. The thermoplastic elastomer composition according to claim 1, which further contains a crosslinking agent.

12. The thermoplastic elastomer composition according to claim 11, wherein, The crosslinking agent is contained in an amount of 2 parts by mass or more with respect to 100 parts by mass of the propylene resin (A).

13. An injection molded article, which contains the thermoplastic elastomer composition according to any one of claims 1 to 12.

14. A film or sheet, which is formed from the injection molded article according to claim 13.

15. An automotive interior material, which is formed from the injection molded article according to claim 13.

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