Thermoplastic elastomer composition and molded article made thereof

Abstract

Provided are: a thermoplastic elastomer composition from which a molded body having excellent feel and transparency can be obtained; and a molded body formed therefrom. The thermoplastic elastomer composition comprises components (A) to (C) below.　Component (A) is a propylene-based polymer; component (B) is a block copolymer and / or a hydrogenated product thereof, the block copolymer having at least two polymerization blocks P mainly composed of an aromatic vinyl compound unit and at least one polymer block Q mainly composed of a conjugated diene compound unit; and compound (C) is organopolysiloxane containing an aryl group.

Description

[Technical field]

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

[0002] Thermoplastic elastomers soften and become fluid when heated, and have rubber elasticity when cooled. Thermoplastic elastomers have moldability similar to that of thermoplastic resins, as well as unique rubber elasticity and are recyclable. For these reasons, thermoplastic elastomers are widely used in automobile parts such as the skin of automobile interior materials, building parts, medical parts, electric wire coating materials, miscellaneous goods, etc.

[0003] Patent Document 1 discloses, as a thermoplastic elastomer composition for injection molding, a so-called styrene-based elastomer including a block copolymer consisting of at least one polymer block A mainly made of an aromatic vinyl compound and at least one polymer block B mainly made of a conjugated diene compound, a hydrogenated block copolymer obtained by hydrogenating the block copolymer, and a propylene-based block copolymer. Patent Document 1 also describes that the styrene-based elastomer can be used for automobile interior materials.

[0004] Patent Document 2 describes that by using a silicone oil having a viscosity (JIS Z8803, 25°C) of 100,000 centistokes (cSt) or more in a styrene-based or olefin-based rubber as a thermoplastic elastomer composition, it is possible to improve low-temperature impact resistance and surface scratch resistance while maintaining mechanical strength.

[0005] [Patent Document 1] JP 2006-83323 A [Patent Document 2] Japanese Patent Application Publication No. 08-176353

[0006] In recent years, there has been a demand for a sense of luxury and comfort in the interior space of an automobile. For this reason, there is a demand for good appearance and tactile feel for the surface of automobile interior materials, such as arm rests and console pads.

[0007] Furthermore, the number of automobile interior spaces with various designs is increasing, and from the viewpoint of design, materials are also required to have decorative properties. Generally, the decorative properties of thermoplastic resins depend on the transparency of the resin, and the higher the transparency, the better the decorative properties.

[0008] However, the molded articles using the thermoplastic elastomer compositions described in Patent Documents 1 and 2 had insufficient transparency. Summary of the Invention

[0009] An object of the present invention is to provide a thermoplastic elastomer composition which can give a molded article having excellent touch and transparency, and a molded article made of the same.

[0010] The present inventors have found that a molded article having excellent touch and transparency can be provided by blending a specific organopolysiloxane with a thermoplastic elastomer composition containing a propylene-based polymer and a block copolymer and / or a hydrogenated product thereof, the block copolymer having at least two polymer blocks P mainly composed of aromatic vinyl compound units and at least one polymer block Q mainly composed of conjugated diene compound units.

[0011] The present invention relates to the following items [1] to [5].

[0012] [1] A thermoplastic elastomer composition comprising the following components (A) to (C): Component (A) Propylene-based polymer Component (B) A block copolymer having at least two polymer blocks P mainly composed of aromatic vinyl compound units and at least one polymer block Q mainly composed of conjugated diene compound units, and / or a hydrogenated product thereof. Component (C): Aryl group-containing organopolysiloxane

[0013] [2] The thermoplastic elastomer composition according to [1], wherein the component (C) is an aralkyl group-containing organopolysiloxane.

[0014] [3] The thermoplastic elastomer composition according to [2], wherein the component (C) is an aralkyl group-containing organopolysiloxane containing a repeating unit represented by the following formula (1):

[0015] [ka]

[0016] R in formula (1) 1 R represents a hydrocarbon group having 1 to 18 carbon atoms. 2 represents an aralkyl group having 7 to 12 carbon atoms.

[0017] [4] R 1 The thermoplastic elastomer composition according to [3], wherein

[0018] [5] A molded article using the thermoplastic elastomer composition according to any one of [1] to [4].

[0019] The present invention also relates to the following <1> ~ <7> The gist of the paper is as follows.

[0020] <1> A thermoplastic elastomer composition comprising the following components (A) to (C): Component (A) Propylene-based polymer Component (B) A block copolymer having at least two polymer blocks P mainly composed of aromatic vinyl compound units and at least one polymer block Q mainly composed of conjugated diene compound units, and / or a hydrogenated product thereof. Component (C) An aralkyl-containing organopolysiloxane having a repeating unit represented by the following formula (1) in the molecule:

[0021] [ka]

[0022] R in formula (1) 1 R represents a hydrocarbon group having 1 to 18 carbon atoms. 2 represents an aralkyl group having 7 to 12 carbon atoms.

[0023] <2> The component (C) is an aralkyl group-containing organopolysiloxane having in its molecule a repeating unit represented by the formula (1) and a repeating unit represented by the following formula (2): <1> The thermoplastic elastomer composition according to claim 1.

[0024] [ka]

[0025] R in Equation (2) 3 and R 4 each independently represents an organic group having 1 to 18 carbon atoms.

[0026] <3> R 1 is a methyl group; <1> or <2> The thermoplastic elastomer composition according to claim 1.

[0027] <4> R 3 and R 4 are each independently an alkyl group having 1 to 3 carbon atoms; <3> The thermoplastic elastomer composition according to claim 1.

[0028] <5> R 3 and R 4 is a methyl group; <4> The thermoplastic elastomer composition according to claim 1.

[0029] <6> The aromatic vinyl compound unit of the component (B) is a styrene unit, and the conjugated diene compound unit is a butadiene unit. <1> ~ <5> 2. The thermoplastic elastomer composition according to claim 1 .

[0030] <7> <1> ~ <6> 2. A molded article using the thermoplastic elastomer composition according to claim 1 . Effect of the Invention

[0031] According to the present invention, it is possible to provide a thermoplastic elastomer composition which can give a molded article having excellent touch and transparency, and a molded article made of the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments. The present invention is not limited to the following description, and can be modified in any manner without departing from the gist of the present invention. In this specification, when "~" is used with a numerical value or a physical property value enclosed therein, the values ​​before and after the "~" are included in the expression.

[0033] [Thermoplastic elastomer composition] The thermoplastic elastomer composition of the present invention is characterized by containing the following components (A) to (C), and may further contain the following component (D). Component (A) Propylene-based polymer Component (B) A block copolymer having at least two polymer blocks P mainly composed of aromatic vinyl compound units and at least one polymer block Q mainly composed of conjugated diene compound units, and / or a hydrogenated product thereof (hereinafter sometimes referred to as "(hydrogenated) block copolymer"). Component (C): Aryl group-containing organopolysiloxane Component (D) Hydrocarbon-based rubber softener

[0034] <Mechanism> The thermoplastic elastomer composition of the present invention exhibits the effect of being able to obtain a molded article having excellent touch and transparency.

[0035] Although the details of why the thermoplastic elastomer composition of the present invention exhibits such effects are not clear, it is presumed as follows.

[0036] Generally, a thermoplastic elastomer composition comprising a propylene-based polymer of component (A) and a (hydrogenated) block copolymer of component (B) has a structure, from a microscopic point of view, in which a plurality of islands of component (B) exist in a sea of ​​component (A), that is, a so-called sea-island structure. The presence of component (C) in such an island-sea structure of components (A) and (B) tends to facilitate fine dispersion of component (B) in the sea of ​​component (A), which is believed to increase the amount of dispersed particles of component (B) with a dispersion diameter smaller than the wavelength of visible light, thereby improving the transparency of the elastomer composition of the present invention.

[0037] In addition, the aryl group contained in component (C) interacts with the aromatic group of the aromatic vinyl compound unit contained in component (B), which makes component (C) more likely to be localized around component (B). This makes it easier for component (C) to be present in large amounts at the interface between components (A) and (B). As a result, it is presumed that light scattering at the interface between components (A) and (B) is suppressed, improving transparency.

[0038] <Component (A)> The propylene polymer of component (A) used in the present invention (hereinafter may be referred to as "propylene polymer (A)") may contain 50% by mass or more of propylene units in the monomer units constituting the propylene polymer (A). From the viewpoints of heat resistance, rigidity, crystallinity, chemical resistance, etc., the content of propylene units in the propylene polymer (A) is preferably 60% by mass or more, more preferably 75% by mass or more, and even more preferably 90% by mass or more. There is no particular upper limit for the content of propylene units, and it may be 100% by mass.

[0039] The content of the propylene unit in component (A) and each of the structural units of the other copolymerization components described below can be determined by infrared spectroscopy.

[0040] The type of the propylene polymer (A) is not particularly limited, and specific examples thereof include a propylene homopolymer and a propylene-ethylene copolymer (e.g., a propylene-ethylene random copolymer, a propylene-ethylene block copolymer). Any of these can be used as the propylene polymer (A).

[0041] The melt flow rate (JIS K7210, 230°C, 21.2N load) of the propylene polymer (A) is not particularly limited, but is usually 0.05 to 200g / 10min, preferably 0.05 to 100g / 10min, and more preferably 0.1 to 80g / 10min. By controlling the melt flow rate within the above range, excellent moldability and good appearance of the obtained molded product can be obtained, and mechanical properties, particularly tensile breaking strength, can be controlled within a desired range.

[0042] The catalyst used in producing the propylene polymer (A) is not particularly limited, but for example, a polymerization method using a stereoregular catalyst is preferred. Examples of the stereoregular catalyst include, but are not limited to, Ziegler catalysts and metallocene catalysts. Among these catalysts, metallocene catalysts are preferred.

[0043] Examples of Ziegler catalysts include, but are not limited to, two-component catalysts consisting of a transition metal component, such as a titanium halide compound such as titanium trichloride, titanium tetrachloride, or trichloroethoxytitanium, or a contact product of the titanium halide compound with a magnesium compound such as a magnesium halide, and an organometallic component, such as an alkylaluminum compound or its halide, hydride, or alkoxide; and three-component catalysts in which an electron donor compound containing nitrogen, carbon, phosphorus, sulfur, oxygen, silicon, or the like is further added to the above components.

[0044] The metallocene catalyst is not limited to the following, but may be, for example, a catalyst consisting of a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton (so-called metallocene compound), a cocatalyst capable of activating the metallocene compound to a stable ionic state by reacting with the metallocene compound, and, if necessary, an organoaluminum compound, and any known catalyst can be used. The metallocene compound is preferably a bridged metallocene compound capable of stereoregular polymerization of propylene, and more preferably a bridged metallocene compound capable of isoregular polymerization of propylene.

[0045] Examples of the method for producing the propylene-based polymer (A) include a slurry method using an inert solvent in the presence of the catalyst, a solution method, a gas phase method substantially without a solvent, and a bulk polymerization method using a polymerization monomer as a solvent. For example, in the case of a slurry method, the polymerization can be carried out in an inert hydrocarbon or liquid monomer such as n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, cyclohexane, benzene, toluene, or xylene. The polymerization temperature is usually -80 to 150°C, preferably 40 to 120°C. The polymerization pressure is preferably 1 to 60 atm. The molecular weight of the resulting propylene-based polymer (A) can be adjusted with hydrogen or other known molecular weight regulators. The polymerization is carried out by a continuous or batch reaction, and the conditions may be those usually used. The polymerization reaction may be carried out in one stage or multiple stages.

[0046] The propylene polymer (A) may be a commercially available product, such as polypropylene block copolymer manufactured by Sunallomer Corporation, and Novatec (registered trademark) PP and WAYMAX (registered trademark) manufactured by Japan Polypropylene Corporation.

[0047] The propylene-based polymer (A) may be used alone or in combination of two or more kinds having different copolymerization compositions, physical properties, and the like.

[0048] <Ingredient (B)> The component (B) used in the present invention is a (hydrogenated) block copolymer having at least two polymer blocks P (hereinafter sometimes simply referred to as "block P") mainly composed of aromatic vinyl compound units and at least one polymer block Q (hereinafter sometimes simply referred to as "block Q") mainly composed of conjugated diene compound units.

[0049] Here, the term "mainly composed of" means that the target monomer unit is contained in the target polymer block in an amount of 50 mol % or more.

[0050] The aromatic vinyl compound constituting the block P is not particularly limited, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. Among these, from the viewpoints of availability and productivity, styrene, α-methylstyrene, and p-methylstyrene are preferably used. Styrene is more preferred.

[0051] The block P may be composed of one type of aromatic vinyl compound unit or two or more types of aromatic vinyl compound units. The block P may contain a monomer unit other than the vinyl aromatic compound unit.

[0052] The conjugated diene compound constituting the block Q is a diolefin having a pair of conjugated double bonds. Examples of the conjugated diene compound include, but are not limited to, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferably used from the viewpoint of productivity. More preferably, 1,3-butadiene is used.

[0053] The block Q may be composed of one type of conjugated diene compound unit or may be composed of two or more types of conjugated diene compound units. The block Q may contain a monomer unit other than the conjugated diene compound unit.

[0054] The block polymer having at least two blocks P and at least one block Q may be linear, branched, radial, or the like.

[0055] The block polymer is preferably a block copolymer represented by the following formula (I) or (II). P-(QP)m (I) (PQ)n (II) In the formula, P represents a block P. Q represents a block Q. m represents an integer of 1 to 5. n represents an integer of 1 to 5. When a plurality of blocks P and a plurality of blocks Q are present, the compound units thereof may be the same or different.

[0056] From the viewpoint of rubber elasticity of the composition, component (B) is preferably a block copolymer represented by formula (I), more preferably a block copolymer represented by formula (I) in which m is 3 or less, still more preferably a block copolymer represented by formula (I) in which m is 2 or less, and particularly preferably a block copolymer represented by formula (I) in which m is 1.

[0057] Component (B) may be a hydrogenated product of a block copolymer having a block P and a block Q. In this case, it is preferably a hydrogenated product of a block copolymer represented by formula (I), more preferably a hydrogenated product of a block copolymer represented by formula (I) in which m is 3 or less, even more preferably a hydrogenated product of a block copolymer represented by formula (I) in which m is 2 or less, and particularly preferably a hydrogenated product of a block copolymer represented by formula (I) in which m is 1.

[0058] The content of block P in the block copolymer of component (B) is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. The content of block P in the block copolymer of component (B) is preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, and particularly preferably 40% by mass or less. Within the above range, the higher the proportion of block P, the better the mechanical strength, and the lower the proportion, the better the flexibility and the less prone to bleeding out. By setting the proportion within the above range, it becomes easier to achieve both mechanical strength and flexibility while suppressing bleeding out.

[0059] The proportion of block Q in the block copolymer of component (B) is preferably high from the standpoints of flexibility and resistance to bleed-out of the thermoplastic elastomer composition, and is preferably low from the standpoint of mechanical strength. The content of block Q in the block copolymer of component (B) is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more. The content of block Q in the block copolymer of component (B) is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and particularly preferably 80% by mass or less. Within the above range, the higher the proportion of block Q, the more excellent the flexibility and the less likely the bleed-out will be, whereas the lower the proportion, the more excellent the mechanical strength. By setting the proportion within the above range, it becomes easier to achieve both mechanical strength and flexibility while suppressing bleed-out.

[0060] The weight average molecular weight (Mw) of the (hydrogenated) block copolymer of component (B) is preferably 10,000 or more, more preferably 30,000 or more, and is preferably 800,000 or less, more preferably 650,000 or less, and even more preferably 500,000 or less. In terms of heat resistance and mechanical strength, the (hydrogenated) block copolymer of component (B) is preferably large within the above range, and is preferably small within the above range in terms of molded appearance, fluidity, and moldability. By setting the Mw of the (hydrogenated) block copolymer of component (B) within the above range, a thermoplastic elastomer composition having excellent heat resistance, mechanical strength, molded appearance, fluidity, and moldability can be obtained.

[0061] Here, Mw is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (hereinafter sometimes abbreviated as "GPC") under the following conditions. (Measurement conditions) Equipment: "150C ALC / GPC" manufactured by Nihon Millipore Column: Showa Denko "AD80M / S" x 3 Detector: FOXBORO infrared spectrophotometer "MIRANIA" Wavelength: 3.42μm Solvent: o-dichlorobenzene Temperature: 140℃ Flow rate: 1cm 3 / min Injection volume: 200 microliters Concentration: 2mg / cm 3 0.2% by mass of 2,6-di-t-butyl-p-phenol was added as an antioxidant.

[0062] Preferred examples of the component (B) include styrene-butadiene-styrene block copolymers and hydrogenated products thereof, and styrene-isoprene / butadiene-styrene block copolymers and hydrogenated products thereof.

[0063] Commercially available products may also be used as component (B). Specific examples of commercially available products include "Kraton (registered trademark) G" manufactured by Kraton Polymers, "Septon (registered trademark)" manufactured by Kuraray Co., Ltd., "Tuftec (registered trademark)" and "SOE (registered trademark)" manufactured by Asahi Kasei Corporation, and "TAIPOL (registered trademark)" manufactured by TSRC.

[0064] The (hydrogenated) block copolymer of component (B) may be used alone or in combination of two or more kinds.

[0065] <Ingredient (C)> The aryl group of the aryl group-containing organopolysiloxane of component (C) used in the present invention is a broad aryl group including heteroaryl groups, and examples thereof include phenyl, naphthyl, tolyl, xylyl, pyridyl, pyrimidinyl, and thienyl groups.In addition, the aryl group-containing organopolysiloxane may have an aryl group, and the aryl group may be contained in the aryl group-containing organopolysiloxane via a linking group such as an alkylene group.An example of such a group containing an aryl group is an aralkyl group.That is, the aryl group-containing organopolysiloxane may be an aralkyl group-containing organopolysiloxane.

[0066] By using such an aryl group-containing organopolysiloxane together with component (A) and component (B), it is possible to improve the tactile feel while maintaining the transparency of the thermoplastic elastomer composition of the present invention.

[0067] The aryl group-containing organopolysiloxane is more preferably an aryl group-containing organopolysiloxane having a repeating unit represented by the following formula (1A) in the molecule.

[0068] [ka]

[0069] In the above formula (1A), R 11 and R 12are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, provided that R 11 and R 12 At least one of R is an aryl group or a group containing an aryl group. 11 and R 12 may both be aryl groups or groups containing an aryl group. R 11 Preferred examples of the group include R 1 and R 2 Similarly, R 12 Preferred examples of the group include R 1 and R 2 Examples include:

[0070] Among these, the aryl group-containing organopolysiloxane is preferably an aralkyl group-containing organopolysiloxane, because it is more excellent in maintaining transparency and improving the tactile feel, and as the aralkyl group-containing organopolysiloxane, an aralkyl group-containing organopolysiloxane having a repeating unit represented by the following formula (1) in the molecule is more preferable.

[0071] [ka]

[0072] R in formula (1) 1 R represents a hydrocarbon group having 1 to 18 carbon atoms. 2 represents an aralkyl group having 7 to 12 carbon atoms.

[0073] In formula (1), R 1 R is a hydrocarbon group having 1 to 18 carbon atoms, and examples of such alkyl groups include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. 1 is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

[0074] R 2is an aralkyl group having 7 to 12 carbon atoms, and examples of such phenylalkyl groups include a benzyl group, a phenylethyl group, a phenylpropyl group, and a 2-phenylpropyl group. From the viewpoints of maintaining transparency and improving the touch, R 2 is preferably a 2-phenylpropyl group.

[0075] The aralkyl group-containing organopolysiloxane of component (C) is preferably an aralkyl group-containing organopolysiloxane having, in the molecule, a repeating unit represented by the above formula (1) and a repeating unit represented by the following formula (2):

[0076] [ka]

[0077] R in Equation (2) 3 and R 4 each independently represents an organic group having 1 to 18 carbon atoms.

[0078] In formula (2), R 3 ,R 4 Examples of the organic group having 1 to 18 carbon atoms include an alkyl group, an aryl group, an alkenyl group, an alkoxy group, and an epoxy group. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a cyclohexyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group, a tetradecyl group, a phenyl group, a methoxy group, and an ethoxy group. From the viewpoint of industrial availability, R 3 ,R 4 is preferably an alkyl group, more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group.

[0079] The aryl group content of the aryl group-containing organopolysiloxane of component (C) is preferably 1 to 60 mol %, more preferably 5 to 55 mol %, and even more preferably 5 to 50 mol %, of all organic groups bonded to silicon atoms. When the aryl group content is within the above range, it becomes easier to obtain a thermoplastic elastomer composition with excellent transparency.

[0080] Similarly, the content of aralkyl groups in the aralkyl group-containing organopolysiloxane of component (C) is preferably 1 to 60 mol %, more preferably 5 to 55 mol %, and even more preferably 5 to 50 mol %, of all organic groups bonded to silicon atoms. When the content of aralkyl groups is within the above range, it becomes easier to obtain a thermoplastic elastomer composition with excellent transparency.

[0081] The kinetic viscosity (25°C) of the aryl group-containing organopolysiloxane of component (C) used in the present invention is preferably 1 cSt or more, more preferably 5 cSt or more, and even more preferably 10 cSt or more. The upper limit of the kinetic viscosity (25°C) of the aryl group-containing organopolysiloxane is not particularly limited, but is preferably 1.5 million cSt or less, more preferably 1 million cSt or less, and even more preferably 500,000 cSt or less. The higher the kinetic viscosity within the above range, the greater the effect of improving abrasion resistance. On the other hand, the lower the kinetic viscosity within the above range, the better the transparency tends to be, and the greater the effect of improving stickiness and the better the touch. By setting it within the above range, the desired abrasion resistance, transparency, and stickiness improvement effect can be obtained.

[0082] Commercially available products may also be used as component (C). Specific examples of commercially available products include "KF-410" and "X22-1877" manufactured by Shin-Etsu Chemical Co., Ltd., "Wacker (registered trademark) TN" ​​manufactured by Wacker Asahi Kasei Silicone Co., Ltd., and "XIAMETER (registered trademark) OFX-0203, 0230" and "DOWSIL (registered trademark) SH 510, 550, 710" manufactured by Dow-Toray Co., Ltd.

[0083] The aryl group-containing organopolysiloxane of component (C) may be used alone or in combination of two or more different types.

[0084] <Ingredient (D)> The thermoplastic elastomer composition of the present invention may contain a hydrocarbon-based rubber softener as component (D). The inclusion of a hydrocarbon-based rubber softener is effective in improving the flexibility and flowability of the thermoplastic elastomer composition of the present invention.

[0085] As the hydrocarbon-based rubber softener, mineral oil-based softeners and synthetic resin-based softeners are preferred because of their high affinity for component (B), and mineral oil-based softeners are more preferred.

[0086] Mineral oil-based softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons. Oils in which 50% or more of the total carbon atoms are derived from paraffinic hydrocarbons are called paraffinic oils, oils in which 30 to 45% of the total carbon atoms are derived from naphthenic hydrocarbons are called naphthenic oils, and oils in which 35% or more of the total carbon atoms are derived from aromatic hydrocarbons are called aromatic oils.

[0087] The hydrocarbon rubber softener used as component (D) may be any one of the above-mentioned various softeners, or two or more of them may be used in combination. Of these, paraffin-based oils are preferred because they have a good hue.

[0088] Examples of synthetic resin-based softeners include polybutene and low molecular weight polybutadiene.

[0089] The kinematic viscosity of the hydrocarbon rubber softener at 40°C measured by a method conforming to JIS K2283 is preferably 20 cSt or more, more preferably 50 cSt or more, and is preferably 800 cSt or less, more preferably 600 cSt or less. Within the above range, the kinetic viscosity of the hydrocarbon-based rubber softener is preferably low in terms of improving the fluidity of the thermoplastic elastomer composition of the present invention, and is preferably high in terms of preventing fogging, etc. By setting the kinetic viscosity within the above range, the fluidity of the thermoplastic elastomer composition of the present invention can be improved while preventing the occurrence of fogging, etc.

[0090] <Mixing ratio> In the thermoplastic elastomer composition of the present invention, the content ratios of component (A) and component (B) relative to the total of 100 mass% are preferably 1 to 99 mass% for component (A) and 99 to 1 mass% for component (B), more preferably 5 to 95 mass% for component (A) and 95 to 5 mass% for component (B), even more preferably 10 to 90 mass% for component (A) and 90 to 10 mass% for component (B), and particularly preferably 25 to 80 mass% for component (A) and 75 to 20 mass% for component (B).

[0091] In the thermoplastic elastomer composition of the present invention, the content of component (C) is preferably 0.01 to 20 parts by mass, more preferably 0.05 to 20 parts by mass, even more preferably 0.1 to 15 parts by mass, particularly preferably 0.1 to 12 parts by mass, and even more preferably 0.5 to 12 parts by mass, per 100 parts by mass of the total of components (A) and (B).

[0092] When the thermoplastic elastomer composition of the present invention contains component (D), the content of component (D) is preferably 0 to 100 parts by mass, more preferably 0 to 90 parts by mass, even more preferably 0 to 85 parts by mass, and particularly preferably 0 to 80 parts by mass, per 100 parts by mass of component (B).

[0093] When the thermoplastic elastomer composition of the present invention contains the propylene-based polymer of component (A) in the above range, the thermoplastic elastomer composition can fully obtain the effects of improving heat resistance and mechanical properties provided by component (A) while fully obtaining the effects of blending the other components.

[0094] When the thermoplastic elastomer composition of the present invention contains the (hydrogenated) block copolymer of component (B) in the above range, the thermoplastic elastomer composition can obtain sufficient heat resistance and oil resistance due to component (B) while fully obtaining the blending effects of the other components.

[0095] By including the aryl group-containing organopolysiloxane of component (C) in the above-mentioned range, the thermoplastic elastomer composition of the present invention can obtain a sufficient effect of improving the tactile feel while maintaining transparency and fully obtaining the blending effects of the other components.

[0096] By containing the hydrocarbon rubber softener of component (D) in the above range, the thermoplastic elastomer composition of the present invention can fully obtain the effect of improving flexibility and flowability provided by component (D) while fully obtaining the blending effects of the other components.

[0097] <Other ingredients> The thermoplastic elastomer composition of the present invention may contain other components (sometimes simply referred to as "other components" in this specification) in addition to the components (A) to (D) as necessary, provided that the object of the present invention is not impaired. Examples of other components include resins and elastomers other than the components (A) and (B) (sometimes collectively referred to as "other resins" in this specification) and various additives.

[0098] Examples of other resins that may be contained in the thermoplastic elastomer composition of the present invention include polyolefin resins (excluding those corresponding to the above-mentioned component (A)), polyester resins, polyamide resins, styrene resins (excluding those corresponding to the above-mentioned component (B)), acrylic resins, polycarbonate resins, polyphenylene ethers, polyvinyl chloride resins, and other resins; olefin-based elastomers such as ethylene-propylene copolymer rubber (EPM), ethylene-propylene-non-conjugated diene copolymer rubber (EPDM), ethylene-butene copolymer rubber (EBM), and ethylene-propylene-butene copolymer rubber; polyamide-based elastomers such as polyamide-polyol copolymers; polyvinyl chloride-based elastomers and polybutadiene-based elastomers; hydrogenated products thereof, or products modified with acid anhydrides or the like to introduce polar functional groups; and products obtained by grafting, randomly, and / or block copolymerizing other monomers; and the like. The above-mentioned other resins may be used alone or in combination of two or more types.

[0099] Examples of additives that may be contained in the thermoplastic elastomer composition of the present invention include molding processing aids such as antioxidants, crystal nucleating agents, lubricants, etc., ultraviolet absorbers, light stabilizers such as hindered amine compounds, hydrolysis resistance improvers, colorants such as pigments and dyes, antistatic agents, conductive agents, reinforcing agents, fillers, plasticizers (excluding those corresponding to the above-mentioned component (D)), release agents, and foaming agents.

[0100] It is effective to use a polysiloxane other than component (C) as a lubricant in the thermoplastic elastomer composition of the present invention. The polysiloxane is a component that imparts wear resistance to the thermoplastic elastomer composition and prevents stickiness specific to elastomers. The type of substituent bonded to the siloxane main chain in the molecular structure of the polysiloxane is not particularly limited, but dimethylpolysiloxane (dimethyl silicone) is preferably used. The kinetic viscosity (25°C) of the polysiloxane is preferably 1 cSt or more, more preferably 5 cSt or more, and even more preferably 10 cSt or more, with no particular upper limit. The higher the kinetic viscosity of the polysiloxane, the higher the effect of improving wear resistance, and the lower the viscosity, the higher the effect of improving stickiness.

[0101] Here, the kinematic viscosity is a kinematic viscosity at 25° C. measured using an Ubbelohde viscometer in accordance with ASTM D445-46T (or JIS Z8803).

[0102] When the thermoplastic elastomer composition of the present invention contains a lubricant such as polysiloxane, the content thereof is preferably 0.1 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the total of components (A) and (B). A content of 0.1 part by mass or more is preferable from the viewpoint of improving abrasion resistance and stickiness resistance, and a content of 15 parts by mass or less is preferable from the viewpoints of mechanical strength, mold contamination, etc.

[0103] The thermoplastic elastomer composition of the present invention may contain, as an antioxidant (heat stabilizer), a hydroxylamine-based antioxidant, a dithiocarbamate-based antioxidant, a hindered phenol-based antioxidant, a sulfur-based antioxidant, a phosphorus-based antioxidant, or the like.

[0104] As the hydroxylamine-based antioxidant, N,N-dialkylhydroxylamines are preferred, and are represented by the formula R a R b NOH (in the formula, R a and R b Each independently represents an alkyl group. a or R b is a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, or a heptadecyl group. Particularly preferred dialkylhydroxylamines are N,N-dioctadecylhydroxylamines, N,N-dihexadecylhydroxylamines, or mixtures thereof. Commercially available products include "Irganox (registered trademark) 1010" manufactured by BASF.

[0105] As the dithiocarbamate-based antioxidant, metal salts of dialkyldithiocarbamic acid are preferred, among which nickel dialkyldithiocarbamate is preferred, and nickel dibutyldithiocarbamate is particularly preferred because of its large effect of improving heat aging resistance.

[0106] Known hindered phenol-based antioxidants can be used, and those having a molecular weight of 500 or more, such as tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, are preferred.

[0107] The sulfur-based antioxidants are compounds containing sulfur, such as thioethers, dithioacid salts, mercaptobenzimidazoles, thiocarbanilides, and thiodipropionate compounds. However, they do not include compounds equivalent to the dithiocarbamate antioxidants. Among these, thiodipropionate compounds are particularly preferred.

[0108] Examples of phosphorus-based antioxidants include phosphorus-containing compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid derivatives, phenylphosphonic acid, polyphosphonates, dialkyl pentaerythritol diphosphites, and dialkyl bisphenol A diphosphites.

[0109] The antioxidants may be used alone or in combination of two or more.

[0110] When the thermoplastic elastomer composition of the present invention contains an antioxidant, the content of the antioxidant is preferably 0.01 to 5 parts by mass per 100 parts by mass of the total of components (A) and (B). A content of 0.01 parts by mass or more is preferable from the viewpoint of improving the heat deterioration resistance, and a content of 5 parts by mass or less is preferable from the viewpoint of preventing problems such as bleeding and the mechanical strength of the composition.

[0111] The hindered amine light stabilizer is a compound containing a hindered piperidine structure, and known compounds can be used. Commercially available hindered amine light stabilizers include the "Tinuvin (registered trademark)" series manufactured by BASF. The hindered amine light stabilizer may be used alone or in combination of two or more kinds.

[0112] When the thermoplastic elastomer composition of the present invention contains a hindered amine-based light stabilizer, the content thereof is preferably 0.005 to 2 parts by mass, more preferably 0.01 to 0.5 parts by mass, per 100 parts by mass of the total of components (A) and (B). When the content is within the above range, the weather resistance is sufficient and bleeding to the surface of the molded article is unlikely to occur, which is preferable.

[0113] The total content of the additives such as the antioxidants in the thermoplastic elastomer composition of the present invention is preferably 2 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the total of component (A) and component (B).

[0114] <Method of producing thermoplastic elastomer composition> The method for producing the thermoplastic elastomer composition of the present invention is not particularly limited, and the composition can be produced, for example, in a conventional manner by dry blending component (A), component (B), and component (C) with component (D) and other components added as necessary, and then melt-kneading the mixture. The mixing device used in this case is not particularly limited, and examples thereof include kneading devices such as a Banbury mixer, a Labo Plastomill, a single screw extruder, a twin screw extruder, etc. Among these, the melt mixing method using an extruder is preferred from the viewpoints of productivity and good kneading properties. The melting temperature during kneading can be appropriately set, but is usually in the range of 130 to 300°C, preferably 150 to 250°C.

[0115] <Application> The thermoplastic elastomer composition of the present invention may be used in any applications, but is particularly useful as a molding material for automobile parts, building parts, medical parts, electric wire covering materials, miscellaneous goods, and the like.

[0116] [Molded body] The thermoplastic elastomer composition of the present invention can be molded into various molded articles. The thermoplastic elastomer composition of the present invention can be molded using various molding methods such as conventional injection molding and extrusion molding. Specific examples of the molded article of the present invention obtained by molding the thermoplastic elastomer composition of the present invention include injection molded articles and extrusion molded articles.

[0117] The molding conditions for injection molding the thermoplastic elastomer composition of the present invention are as follows. The molding temperature is usually 160 to 250°C, and preferably 170 to 220°C. The injection pressure is usually 5 to 100 MPa, and preferably 10 to 80 MPa. The mold temperature is usually 10 to 80°C, and preferably 20 to 60°C.

[0118] The injection molded article obtained by injection molding the thermoplastic elastomer composition of the present invention can also be used as a composite molded article by heat fusing it with an olefin-based hard resin such as a propylene resin.

[0119] The molded article of the present invention is useful as automobile parts, building parts, medical parts, electric wire coating materials, miscellaneous goods, etc., and is particularly useful as the surface of automobile interior materials, such as armrests and console pads, because of its excellent transparency, appearance and feel. EXAMPLES

[0120] The specific embodiments of the present invention will be described in more detail below using examples. The present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. The values ​​of various manufacturing conditions and evaluation results in the following examples are meant as preferred upper or lower limit values ​​in the embodiments of the present invention, and a preferred range may be a range defined by a combination of the above-mentioned upper or lower limit value and the values ​​of the following examples or values ​​between the examples.

[0121] In the following Examples and Comparative Examples, the raw materials used in the preparation of the thermoplastic elastomer compositions and the methods for evaluating the obtained thermoplastic elastomer compositions are as follows.

[0122] [Raw materials used] <Component (A)> A-1: "Novatec (registered trademark) PP BC06C" manufactured by Japan Polypropylene Corporation Propylene-Ethylene Block Copolymer Propylene unit content: 91% by mass MFR (JIS K7210, 230℃, 21.2N load): 60g / 10 minutes

[0123] <Ingredient (B)> B-1: “TAIPOL (registered trademark) 6159” manufactured by TSRC Hydrogenated styrene-butadiene-styrene block copolymer Weight average molecular weight: 400,000 Styrene unit content: 30% by mass B-2: Asahi Kasei Corporation "SOE-SS (registered trademark) S1605" Hydrogenated styrene-butadiene-styrene block copolymer Weight average molecular weight: 200,000 Styrene unit content: 60% by mass

[0124] <Ingredient (C)> C-1: Shin-Etsu Chemical Co., Ltd. "KF-410" An aralkyl group-containing organopolysiloxane having a repeating unit represented by the formula (1) and a repeating unit represented by the formula (2): R in formula (1) 1 : Methyl group R in formula (1) 2 : 2-phenylpropyl group R in Equation (2) 3 ,R 4 : Methyl group Aralkyl group content: 39 mol% Kinematic viscosity (25℃): 900cSt

[0125] <Ingredient (D)> D-1: Idemitsu Kosan's "Diana Process Oil PW90" Paraffin oil Kinematic viscosity (40℃): 90cSt

[0126] <Component (X)> X-1: Toray Dow Corning "BY27-001" Dimethylpolysiloxane Masterbatch Dimethylpolysiloxane content: 50% by mass X-2: Shin-Etsu Chemical Co., Ltd. "KF96-1000cs" Dimethylpolysiloxane Kinematic viscosity (25℃): 1000cSt

[0127] <Other additives> E-1: BASF "Irganox (registered trademark) 1010" Hindered phenol antioxidants

[0128] [Evaluation of Thermoplastic Elastomer Composition] <Tactile sensation> The injection-molded articles (350 mm × 100 mm × 2 mm) made from the pellets of the thermoplastic elastomer compositions obtained in the Examples and Comparative Examples were examined for tactile sensation when touched with three fingers of a human hand, and were evaluated according to the following criteria. The feel of the injection molded article is preferably such that no bleeding occurs on the surface and the article does not stick to the hands, and more preferably has a smooth feel. A: It is smooth and does not feel sticky on the hands. B: It is slightly dry and does not feel sticky on the hands. C: Sticky or dry but feels sticky on hands

[0129] <Transparency: Total light transmittance> For injection molded articles (350 mm × 100 mm × 2 mm) prepared from the pellets of the thermoplastic elastomer compositions obtained in the Examples and Comparative Examples, the total light transmittance (unit: %) in the thickness direction was measured using a NDH-2000 type haze meter manufactured by Nippon Denshoku Industries Co., Ltd.

[0130] [Examples 1 to 4, Comparative Examples 1 to 8] The raw materials were mixed according to the composition shown in Table 1, and the resulting mixture was melt-kneaded (cylinder temperature 180°C to 200°C) using a twin-screw kneader to produce pellets of a thermoplastic elastomer composition. The resulting thermoplastic elastomer composition was injected and filled at an injection speed of 40 mm / sec into a sheet-shaped mold of length 350 mm x width 100 mm x thickness 2 mm using an electric injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd.) with a clamping force of 180t, a cylinder temperature of 200°C, and a mold temperature of 40°C. After filling was completed, the molded injection product was cooled for 30 seconds and then removed. The obtained injection molded product was evaluated for touch and transparency, and the results are shown in Table 1.

[0131] [Table 1]

[0132] [Evaluation Results] The following can be said from Table 1:

[0133] Comparative Examples 1, 3 and 6 do not contain polysiloxane and have poor feel. Comparative Example 2 contained dimethylpolysiloxane and had an excellent feel, but had poor transparency compared to Comparative Example 1.

[0134] Example 1 contains a propylene polymer as component (A), a hydrogenated block copolymer as component (B), and an aryl group-containing organopolysiloxane as component (C), and therefore has an excellent feel and is also excellent in transparency compared to Comparative Example 2, which contains dimethylpolysiloxane. The transparency of Example 1 is almost the same as that of Comparative Example 1, which does not contain polysiloxane.

[0135] Comparative Examples 4, 5 and 8 contained dimethylpolysiloxane and had an excellent feel to the touch, but had poor transparency compared to Comparative Example 3.

[0136] Example 2 contains a propylene polymer as component (A), a hydrogenated block copolymer as component (B), and an aryl group-containing organopolysiloxane as component (C), and therefore has an excellent feel and is also excellent in transparency compared to Comparative Examples 4 and 5, which contain dimethylpolysiloxane. The transparency of Example 2 is almost the same as that of Comparative Example 3, which does not contain polysiloxane.

[0137] Comparative Example 7 contained dimethylpolysiloxane and had an excellent feel, but had poor transparency compared to Comparative Example 6.

[0138] Example 3 contains a propylene polymer as component (A), a hydrogenated block copolymer as component (B), and an aryl group-containing organopolysiloxane as component (C), and therefore has an excellent touch and is also excellent in transparency compared to Comparative Example 7, which contains dimethylpolysiloxane. The transparency of Example 3 is even improved compared to Comparative Example 6, which does not contain polysiloxane.

[0139] Example 4 contains a propylene-based polymer as component (A), a hydrogenated block copolymer as component (B), and an aryl group-containing organopolysiloxane as component (C), and therefore has an excellent feel to the touch and is also excellent in transparency as compared with Comparative Examples 4, 5, and 8 which contain only dimethylpolysiloxane.

[0140] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2020-013855 filed on January 30, 2020, and Japanese Patent Application No. 2020-172653 filed on October 13, 2020, both of which are incorporated by reference in their entireties. [Industrial Applicability]

[0141] Molded articles obtained from the thermoplastic elastomer composition of the present invention have excellent transparency and feel, and are therefore suitable for use in automobile parts such as automobile interior materials, building parts, medical parts, electric wire coating materials, miscellaneous goods, and the like.

Claims

1. A thermoplastic elastomer composition comprising the following components (A) to (C): Component (A) Propylene-based polymer Component (B) A block copolymer having at least two polymer blocks P mainly composed of aromatic vinyl compound units and at least one polymer block Q mainly composed of conjugated diene compound units, and / or a hydrogenated product thereof. Component (C): Aryl Group-Containing Organopolysiloxane

2. 2. The thermoplastic elastomer composition according to claim 1, wherein said component (C) is an aralkyl group-containing organopolysiloxane.

3. 3. The thermoplastic elastomer composition according to claim 2, wherein the component (C) is an aralkyl group-containing organopolysiloxane containing a repeating unit represented by the following formula (1): 【Chemistry 1】 R in formula (1) １ R represents a hydrocarbon group having 1 to 18 carbon atoms. ２ represents an aralkyl group having 7 to 12 carbon atoms.

4. The R １ The thermoplastic elastomer composition according to claim 3 , wherein is a methyl group.

5. A molded article using the thermoplastic elastomer composition according to any one of claims 1 to 4.

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