JP2016011396A - Thermoplastic elastomer composition, molded article and skin for instrument panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition that is excellent in flexibility and easily fracturable property in a wide range of temperature and when used as a skin for an instrument panel, enables the skin to easily deploy upon deploying an air bag, and to provide the skin for the instrument panel made of the thermoplastic elastomer composition.SOLUTION: The thermoplastic elastomer composition is provided which contains following a component (a), a component (b) and a component (c) and is obtained by a dynamic heat treatment of a thermoplastic elastomer composition containing the component (a) of 10 to 85 wt.%, the component (b) of 5 to 60 wt.% and the component (c) of 5 to 60 wt.% based on the total amount of the component (a), the component (b) and the component (c) in the presence of the following component (d). The component (a): an oil-extended ethylene α-olefin non-conjugated diene copolymer rubber, the component (b): a polypropylene resin, the component (c): a polyethylene produced by high pressure method and having a density of 0.910 to 0.940 g/cm, and the component (d): an organic peroxide.

Description

  The present invention relates to a thermoplastic elastomer composition. Specifically, the present invention relates to a thermoplastic elastomer composition excellent in flexibility and easily breakability, a molded body formed by molding the thermoplastic elastomer composition, and a skin for an instrument panel comprising the thermoplastic elastomer composition. About.

  Conventionally, automotive interior seats used for instrument panel skins are laminated with a polyvinyl chloride layer embossed with a leather surface and a foam layer, and optionally a resin base layer. The body has been used. However, in order to eliminate the need for environmental issues such as weight reduction, recyclability, and easy incineration of automobile parts, heat resistance, cold resistance, heat aging resistance, light resistance, odor, appearance cheapness, etc. Thermoplastic elastomer materials (hereinafter sometimes simply abbreviated as “TPO”) are in practical use.

  As an example of TPO that can be used for such an automobile interior skin, Patent Document 1 discloses an elastomer composition for a skin material containing an olefin copolymer rubber, an olefin copolymer, and crystalline paraffin. . Further, as TPO with improved tensile strength, Patent Document 2 discloses an elastomer comprising a peroxide-crosslinked olefin copolymer rubber, a peroxide-decomposable olefin-based plastic, and a peroxide-crosslinked olefin-based plastic. Yes. Furthermore, as TPO with improved oil resistance of the skin material, Patent Document 3 discloses an elastomer for skin material containing olefin copolymer rubber, polypropylene resin, mineral oil softener and high density polyethylene. .

Japanese Patent Laid-Open No. 6-1888 JP 7-33917 A JP 2003-12878 A

  According to the detailed study by the present inventors, in the skin using the conventional TPO as described in Patent Documents 1 to 3 above, the instrument is provided with an airbag mechanism because the material is not easily broken. When used for the panel skin, there is a problem that a process of cutting a laminate such as urethane of the foam layer is necessary and costly, and depending on the shape, the TPO skin tends to stretch, so that the airbag deployment is delayed. I found out there was a problem. In particular, the present inventors are equipped with an air bag mechanism in order to exhibit good air bag deployment performance in a wide temperature range from a low temperature (about −20 ° C.) to a high temperature (about 85 ° C.) in recent high demands. The instrument panel skin requires a thermoplastic elastomer that is easily breakable in the above temperature range. When conventional TPO is applied, even if easy breakability is obtained at low temperatures, it is easy at high temperatures. A problem has been found that the breakability may be insufficient.

  The present invention is intended to solve the above-described problems in the prior art, and is excellent in flexibility, easy breakability in a wide temperature range, and when used as a skin for an instrument panel. It is an object of the present invention to provide a thermoplastic elastomer composition that can be easily developed when the bag is deployed, and an instrument panel skin comprising the thermoplastic elastomer composition.

  As a result of intensive studies to solve the above problems, the present inventors have developed a thermoplastic elastomer composition containing specific amounts of oil-extended ethylene / α-olefin / conjugated diene copolymer rubber, polypropylene resin and specific polyethylene, respectively. The present inventors have found that a thermoplastic elastomer composition obtained by dynamic heat treatment in the presence of a peroxide can solve the above-mentioned problems, and has reached the present invention. That is, the gist of the present invention resides in the following [1] to [13].

[1] The following component (a), component (b) and component (c) are included, and component (a) is 10 to 85% by weight based on the total amount of component (a), component (b) and component (c). A thermoplastic elastomer composition obtained by dynamic heat treatment of a composition containing 5 to 60% by weight of component (b) and 5 to 60% by weight of component (c) in the presence of the following component (d).
Component (a): Oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber component (b): Polypropylene resin component (c): Density produced by high pressure method is 0.910 to 0.940 g / cm ³ polyethylene component (d): organic peroxide

[2] The thermoplastic elastomer according to [1], wherein in the component (a), the weight average molecular weight of the ethylene / α-olefin / non-conjugated diene copolymer rubber part is 300,000 or more and 1,000,000 or less. Composition.

[3] The following component (e) is included, and the content thereof is 1 to 200 parts by weight with respect to a total of 100 parts by weight of the components (a) to (c) of the thermoplastic elastomer composition. 2]. The thermoplastic elastomer composition described in 2].
Component (e): Non-oil-extended ethylene / α-olefin copolymer rubber

[4] The thermoplastic elastomer composition according to [3], which contains at least non-oil-extended ethylene / α-olefin / nonconjugated diene copolymer rubber as the component (e) of the thermoplastic elastomer composition.

[5] The thermoplastic elastomer composition according to [3] or [4], wherein the component (e) has a weight average molecular weight of 100,000 or more and less than 300,000.

[6] The thermoplastic elastomer composition according to any one of [3] to [5], wherein the weight ratio of the component (a) to the component (e) is 1: 0.3 to 1:10.

[7] The composition according to [1] to [6], comprising the following component (f) and having a content of 0.1 to 200 parts by weight with respect to a total of 100 parts by weight of the components (a) to (c): The thermoplastic elastomer composition according to any one of the above.
Component (f): Hydrocarbon softener

[8] The thermoplastic elastomer composition according to any one of [1] to [7], which is obtained by dynamic heat treatment in the presence of the following component (g).
Component (g): Crosslinking aid

[9] A molded article formed by molding the thermoplastic elastomer composition according to any one of [1] to [8].

[10] The molded article according to [9], which is formed by injection molding.

[11] The molded product according to [9], which is formed by extrusion molding.

[12] A skin for an instrument panel comprising the thermoplastic elastomer composition according to any one of [1] to [8].

[13] The instrument panel skin according to [12], comprising an airbag mechanism.

  The thermoplastic elastomer of the present invention is excellent in flexibility and easy breakability in a wide temperature range from a low temperature region to a high temperature region. For this reason, the molded body formed by molding the thermoplastic elastomer composition of the present invention, in particular, the instrument panel skin made of the thermoplastic elastomer composition of the present invention is easily deployed in a wide temperature range when the airbag is deployed. Therefore, there is an advantage of excellent safety.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, in this invention, when expressing by putting a numerical value or a physical-property value before and behind using "-", it shall use as what includes the value before and behind.

[Thermoplastic elastomer composition]
The thermoplastic elastomer composition of the present invention comprises the following component (a), component (b) and component (c), with respect to the total amount of component (a), component (b) and component (c), a) obtained by dynamic heat treatment of a composition containing 10 to 85% by weight, component (b) 5 to 60% by weight, and component (c) 5 to 60% by weight in the presence of the following component (d). is there.
Component (a): Oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber component (b): Polypropylene resin component (c): Density produced by high pressure method is 0.910 to 0.940 g / cm ³ polyethylene component (d): organic peroxide

  The thermoplastic elastomer composition of the present invention has an effect of being easily breakable in a wide temperature range from a low temperature region (about −20 ° C.) to a high temperature region (about 85 ° C.). In the thermoplastic elastomer composition of the present invention, the combination of the component (a) and the component (c) makes the low temperature region easy to break, and the component (c) also makes the high temperature region easy to break. It is thought to become.

[Component (a): Oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber]
The component (a) oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber used in the present invention is a mixture of an ethylene / α-olefin / non-conjugated diene copolymer rubber and a hydrocarbon rubber softener. The thermoplastic elastomer composition of the present invention has an ethylene / α-olefin / non-conjugated diene copolymer rubber and hydrocarbon before mixing the component (a) with the component (b) and / or the component (c). It means a mixture with a rubber softener. Hereinafter, the ethylene / α-olefin / non-conjugated diene copolymer rubber part and the hydrocarbon rubber softener part in the oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber of component (a) will be described. .

The α-olefin unit in the ethylene / α-olefin / non-conjugated diene copolymer rubber part of component (a) includes propylene unit, 1-butene unit, 3-methyl-1-butene unit, 1-pentene unit, 4 -Methyl-1-pentene unit, 1-hexene unit, 4-methyl-1-hexene unit, 1-heptene unit, 1-octene unit, 1-decene unit and the like. Among these, the α-olefin unit mentioned above as the propylene unit, 1-butene unit, 1-hexene unit or more may be contained alone or in combination of two or more.

  Non-conjugated diene units in the ethylene / α-olefin / non-conjugated diene copolymer rubber part of component (a) include dicyclopentadiene units, 1,4-hexadiene units, cyclooctadiene units, methylene norbornene units, and ethylidene norbornene. Examples thereof include vinylidene norbornene units. Among these, an ethylidene norbornene unit and / or vinylidene norbornene unit is preferable because an appropriate cross-linked structure can be given to the ethylene / α-olefin / non-conjugated diene copolymer rubber. The non-conjugated diene units listed above may be included alone or in combination of two or more.

  The ethylene unit content in the ethylene / α-olefin / non-conjugated diene copolymer rubber part is preferably 50% by weight or more, more preferably based on the total amount of the monomer units constituting the component (a). Is 55% by weight or more, on the other hand, preferably 90% by weight or less, more preferably 80% by weight or less. It is preferable for the ethylene unit content to be in the above range in order to provide appropriate flexibility.

  The content of the α-olefin unit in the ethylene / α-olefin / non-conjugated diene copolymer rubber part is preferably 10% by weight or more based on the total amount of the monomer units constituting the component (a). More preferably 20% by weight or more, while preferably 45% by weight or less, more preferably 35% by weight or less. It is preferable that the content of the α-olefin unit is in the above range in order to provide appropriate flexibility.

  Furthermore, the content of the non-conjugated diene unit in the ethylene / α-olefin / non-conjugated diene copolymer rubber part is preferably 1% by weight or more based on the total amount of the monomer units constituting the component (a). Yes, preferably 3% by weight or more, while preferably 10% by weight or less, preferably 8% by weight or less. When the content of the non-conjugated diene unit is not less than the above lower limit, it is preferable from the viewpoint of increasing the degree of crosslinking of the thermoplastic elastomer, and when it is not more than the above upper limit, it is preferable from the viewpoint of moldability.

  The content of each structural unit in the ethylene / α-olefin copolymer rubber part can be determined by infrared spectroscopy.

  The weight average molecular weight in terms of polypropylene by gel permeation chromatography method (GPC method) of the ethylene / α-olefin / non-conjugated diene copolymer rubber part in component (a) is preferably 300,000 or more, More preferably, it is 350,000 or more, More preferably, it is 400,000 or more. The weight average molecular weight of component (a) is preferably 1,000,000 or less, more preferably 900,000 or less, and still more preferably 800,000 or less. The weight average molecular weight of the component (a) is preferably from the viewpoint of appearance when it is less than the above upper limit value, and it is preferable from the viewpoint of preventing bleeding out of the hydrocarbon rubber softener when it is at least the above lower limit value.

The measurement conditions of the GPC method for the ethylene / α-olefin / non-conjugated diene copolymer rubber portion in component (a) are as follows.
Equipment: Waters 150C
Column: Shodex AD806MS × 3 (8.0 mm inner diameter × 300 mm length)
Detector: IR (dispersion type, 3.42 μm)
Solvent: ODCB
Temperature: 140 ° C
Flow rate: 1.0 mL / min Injection volume: 200 μL
Concentration: 10 mg / mL
Calibration sample: Polydisperse standard polyethylene Calibration method: Polypropylene conversion using Mark-Houwink equation

  Examples of the hydrocarbon rubber softener part include mineral oil softeners and synthetic resin softeners. Mineral oil softeners are preferred from the viewpoint of affinity with other components. The mineral oil softener is generally a mixture of aromatic hydrocarbons, naphthenic hydrocarbons and paraffinic hydrocarbons, and paraffinic oils in which 50% or more of all carbon atoms are paraffinic hydrocarbons. Those having 30 to 45% of all carbon atoms are called naphthenic oils, and those having 35% or more of all carbon atoms being aromatic hydrocarbons are called aromatic oils. Among these, it is preferable to use paraffinic oil as the softener part for hydrocarbon rubber of component (a). The hydrocarbon rubber softener part may be used alone or in combination of two or more.

  In the component (a), the content ratio of the ethylene / α-olefin / non-conjugated diene copolymer rubber part and the hydrocarbon rubber softener part is [the ethylene / α-olefin / non-conjugated diene copolymer rubber part]. Weight] / [Weight of hydrocarbon-based rubber softener part] is usually 100/10 or more, preferably 100/20 or more, and usually 100/150 or less, preferably 100/120 or less. It is.

  The Mooney viscosity ML (1 + 4) (125 ° C.) of the component (a) is usually 20 to 100 or less, preferably 30 to 90.

  As a method (oil extension method) for producing the component (a) oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber, a known method can be used. As an oil spreading method, for example, using a mixing roll or a Banbury mixer, a method in which an ethylene / α-olefin / non-conjugated diene copolymer rubber part and a mineral oil-based rubber softener part are mechanically kneaded and oil-extended. , A method of adding a predetermined amount of a softening agent for a mineral oil-based rubber to an ethylene / α-olefin / non-conjugated diene copolymer rubber, and then removing the solvent by a method such as steam stripping, crumb-like ethylene / α -A method in which a mixture of an olefin / non-conjugated diene copolymer rubber part and a mineral oil-based rubber softener part is impregnated by stirring with a Henschel mixer or the like.

  The oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber of component (a) can be obtained as a commercial product. For example, a corresponding product can be selected and used from JSR EPR manufactured by JSR, Mitsui EPT manufactured by Mitsui Chemicals, Espren (registered trademark) manufactured by Sumitomo Chemical, Keltan (registered trademark) manufactured by LANXESS, and the like.

[Component (b): Polypropylene resin]
The polypropylene resin of component (b) used in the present invention is a polyolefin resin having a propylene unit content of more than 50% by weight based on all monomer units. In the thermoplastic elastomer composition of the present invention, component (b) contributes to moldability.

  The type of the polypropylene resin of component (b) is not particularly limited, and any of a propylene homopolymer, a propylene random copolymer, a propylene block copolymer, and the like can be used. One of these may be used, or two or more may be used in combination.

  When component (b) is a propylene random copolymer, the monomers copolymerized with propylene include ethylene, 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene, 1- Examples include hexene, 4-methyl-1-pentene, 1-octene and the like. In addition, when component (b) is a propylene block copolymer, a propylene block copolymer obtained by polymerization in multiple stages can be mentioned. More specifically, polypropylene is polymerized in the first stage, and second Examples thereof include a propylene block copolymer obtained by polymerizing a propylene / ethylene copolymer in a stage.

  The content of propylene units in the polypropylene resin of component (b) is preferably 60% by weight or more, more preferably 75% by weight or more, and further preferably 90% by weight or more. When the content of the propylene unit is not less than the above lower limit value, heat resistance and rigidity tend to be good. On the other hand, the upper limit is not particularly limited, and is usually 100% by weight. In addition, content of the propylene unit of polypropylene resin can be calculated | required by an infrared spectroscopy.

  The melt flow rate (MFR) at 230 ° C. and a load of 21.2 N of the component (b) is usually 0.05 g / 10 min or more, preferably 0.1 g / 10 min or more, more preferably from the viewpoint of fluidity. Is 0.5 g / 10 min or more. On the other hand, the MFR of the component (b) is usually 100 g / 10 min or less, and from the viewpoint of moldability, it is preferably 70 g / 10 min or less, more preferably 50 g / 10 min or less, and particularly easy breakage. From the viewpoint of properties, it is more preferably 30 g / 10 min or less, particularly preferably 10 g / 10 min or less.

  As a method for producing the propylene-based resin as the component (b), a known polymerization method using a known olefin polymerization catalyst is used. For example, a multistage polymerization method using a Ziegler-Natta catalyst can be mentioned. As this multistage polymerization method, a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method, and the like can be used, and these may be produced by combining two or more thereof.

  In addition, as the component (b) propylene resin, a commercially available product can be used. Commercially available polypropylene resins can be procured from the manufacturers listed below and can be appropriately selected. Available commercial products include Prime Polymer's Prime Polypro (registered trademark), Sumitomo Chemical Sumitomo Noblen (registered trademark), Sun Allomer's polypropylene block copolymer, Nippon Polypro's Novatec (registered trademark) PP, LyondellBasel Moplen (R), ExxonMobil's ExxonMobil PP, Formosa Plastics' Formolene (R), Borealis's Borealis PP, LG Chemical's SEETEC PP, A. Schulman's ASI POLYPROPYLENE, INEOS Olefins & Polymers, Inc. of INEOS PP, Braskem's Braskem PP, SAMSUNG TOTAL PETROCHEMICALS's Sumsung Total, Sabic's Sabic (registered trademark) PP, TOTAL PETROCHEMICALS company of TOTAL PETROCHEMICALS Polypropylene, SK Corporation of YUPLENE ( Registered trademark).

[Component (c): Polyethylene produced by a high pressure method and having a density of 0.910 to 0.940 g / cm ³ ]
The polyethylene of component (c) used in the present invention is a polyethylene having a density of 0.910 to 0.940 g / cm ³ produced by a high pressure method, which is a method of radical polymerization of ethylene at a high temperature and a high pressure. This is called density polyethylene (LDPE). By using such a low-density polyethylene in combination with component (a) as component (c), the thermoplastic elastomer composition of the present invention has remarkably good breakability.

  In addition, what is generally called linear low density polyethylene (LLDPE) corresponds to the above range in density, but is not obtained by the high pressure method, and is distinguished from component (c) in the present invention. It is. When the component (c) is used as in the present invention, the easy breakability in the high temperature region is remarkably improved as compared with the case where the linear low density polyethylene is used without using the component (c).

The density of the component (c) is 0.940 g / cm ³ or less. When the density is larger than this value, the flexibility of the resulting thermoplastic elastomer composition is lowered, and particularly from room temperature (23 ° C.) to high temperature. It becomes difficult to break in the region. From the viewpoint of these with better ones, the density of component (c), preferably at 0.935 g / cm ³ or less, more preferably 0.930 g / cm ³ or less. On the other hand, the lower limit of the density of the component (c) is 0.910 g / cm ³ . The density of the component (c) is a value measured based on JIS K7112.

  The melt flow rate (MFR) of component (c) is preferably 0.05 g / 10 min or more, preferably 0.1 g / 10 min or more, more preferably 0.5 g / 10 min or more, Usually, it is 100 g / 10 minutes or less, Preferably it is 50 g / 10 minutes or less, More preferably, it is 20 g / 10 minutes or less, More preferably, it is 10 g / 10 minutes or less. It is preferable for the melt flow rate of the component (c) to be equal to or higher than the lower limit because the fluidity of the thermoplastic elastomer composition is good and the appearance tends to be good. On the other hand, it is preferable from the viewpoint of moldability of the thermoplastic elastomer composition that the melt flow rate of the component (c) is not more than the above upper limit. The thermoplastic elastomer composition of component (c) can be measured under the conditions of a measurement temperature of 190 ° C. and a load of 21.2 N based on JIS K7210.

  The polyethylene of component (c) can be obtained as a commercial product. Examples of the commercially available products include Novatec PE manufactured by Nippon Polyethylene Co., Ltd., Sumikasen manufactured by Sumitomo Chemical Co., Ltd., UBE polyethylene manufactured by Ube Maruzen Polyethylene Co., Ltd., and the like.

[Component (d): Organic peroxide]
In the thermoplastic elastomer composition of the present invention, the organic peroxide of component (d) acts as a crosslinking agent in the dynamic heat treatment.

  As the organic peroxide of component (d), any of aromatic organic peroxides and aliphatic organic peroxides can be used. Specifically, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl -2,5-di (t-butylperoxy) hexyne-3, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-di (t-butylperoxy) -3,3,5 -Dialkyl peroxides such as trimethylcyclohexane; t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2 Peroxyesters such as, 5-di (benzoylperoxy) hexyne-3; acetyl peroxide, lauroyl peroxide, benzoy Peroxide, p- chlorobenzoyl peroxide, hydroperoxide, and the like, such as 2,4-dichlorobenzoyl peroxide and the like. Among these, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane is preferable. In addition, the organic peroxide of the component (d) mentioned above may be used alone or in combination of two or more.

[Component (e): Non-oil-extended ethylene / α-olefin copolymer rubber]
The thermoplastic elastomer composition of the present invention preferably contains the following component (e). The non-oil-extended ethylene / α-olefin copolymer rubber of the component (e) that can be used in the present invention is a copolymer rubber containing an ethylene unit and an α-olefin unit, and the component (e) is used. Thus, the easy breakability can be further improved.
Component (e): Non-oil-extended ethylene / α-olefin copolymer rubber

  As the α-olefin unit in the component (e), propylene unit, 1-butene unit, 2-methylpropylene unit, 1-pentene unit, 3-methyl-1-butene unit, 1-hexene unit, 4-methyl-1 -A pentene unit, 1-octene unit, etc. can be illustrated. Among these, an α-olefin unit is preferably an α-olefin unit having 3 to 10 carbon atoms, and more preferably a propylene unit, a 1-butene unit, a 1-hexene unit, or a 1-octene unit. The α-olefin unit may contain only one type or two or more types.

  The component (e) non-oil-extended ethylene / α-olefin copolymer rubber is not only an ethylene unit and an α-olefin unit, but also other monomer such as a monomer unit based on a non-conjugated diene (non-conjugated diene unit). It may preferably have a body unit, and particularly preferably contains a non-oil-extended ethylene / α-olefin copolymer rubber having a non-conjugated diene unit. Examples of non-conjugated diene units include 1,4-hexadiene units, 1,6-octadiene units, 2-methyl-1,5-hexadiene units, 6-methyl-1,5-heptadiene units, and 7-methyl-1 , 6-octadiene units and the like chain non-conjugated diene units; cyclohexadiene units, dicyclopentadiene units, methyltetrahydroindene units, 5-vinylnorbornene units, 5-ethylidene-2-norbornene units, 5-methylene-2- And cyclic non-conjugated diene units such as a norbornene unit, a 5-isopropylidene-2-norbornene unit, and a 6-chloromethyl-5-isopropylenyl-2-norbornene unit. Among these, it is preferable that a 5-ethylidene-2-norbornene unit and a dicyclopentadiene unit are included.

  In the non-oil-extended ethylene / α-olefin copolymer rubber of component (e), the content of ethylene units is preferably 50% by weight or more based on the total amount of monomer units constituting component (e). , More preferably 55% by weight or more, while preferably 90% by weight or less, more preferably 80% by weight or less. It is preferable that the content of the ethylene unit is in the above range because moderate flexibility is provided.

  In the non-oil-extended ethylene / α-olefin copolymer rubber of component (e), the content of α-olefin units is preferably 10% by weight with respect to the total amount of monomer units constituting component (e). Or more, more preferably 20% by weight or more, while preferably 50% by weight or less, more preferably 40% by weight or less. It is preferable that the content of the α-olefin unit is in the above range in order to provide appropriate flexibility.

  In the non-oil-extended ethylene / α-olefin copolymer rubber of the component (e), the content of the non-conjugated diene unit is usually 10% by weight with respect to the total amount of the monomer units constituting the component (e). Or less, preferably 5% by weight or less.

  The content of each constituent unit of the non-oil-extended ethylene / α-olefin copolymer rubber can be determined by infrared spectroscopy.

Specific examples of the component (e) ethylene / α-olefin copolymer rubber include ethylene / propylene copolymer rubber, ethylene / 1-butene copolymer rubber, ethylene / 1-hexene copolymer rubber, Ethylene / 1-octene copolymer rubber, ethylene / propylene / 1-butene copolymer rubber, ethylene / propylene / 1-hexene copolymer rubber, ethylene / propylene / 1-octene copolymer rubber, ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber, ethylene / propylene / dicyclopentadiene copolymer rubber, ethylene / propylene / 1,4-hexadiene copolymer rubber, ethylene / propylene / 5-
An example is vinyl-2-norbornene copolymer rubber. These may be used alone or in combination of two or more. Among these, ethylene / propylene copolymer rubber, ethylene / 1-butene copolymer rubber, ethylene / 1-octene copolymer rubber, ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber are preferable, Ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber is particularly preferred.

  The weight average molecular weight in terms of polypropylene by the gel permeation chromatography method (GPC method) of component (e) is preferably less than 300,000, more preferably less than 280,000, still more preferably 250, Less than 000. The weight average molecular weight of component (e) is preferably 100,000 or more, more preferably 120,000 or more, and further preferably 150,000 or more. When the weight average molecular weight of the component (e) is less than the above upper limit value, it is preferable from the viewpoint of suppressing generation of foreign matters and improving the appearance, and when it is equal to or more than the above lower limit value, it is preferable from the viewpoint of the design properties of the extruded product .

The measurement conditions of the GPC method of component (e) are as follows.
Equipment: Waters 150C
Column: Shodex AD806MS × 3 (8.0 mm inner diameter × 300 mm length)
Detector: IR (dispersion type, 3.42 μm)
Solvent: ODCB
Temperature: 140 ° C
Flow rate: 1.0 mL / min Injection volume: 200 μL
Concentration: 10 mg / mL
Calibration sample: Polydisperse standard polyethylene Calibration method: Polypropylene conversion using Mark-Houwink equation

  The Mooney viscosity ML (1 + 4) (125 ° C.) of the component (e) is usually 10 to 100 or less, preferably 15 to 95.

  As a method for producing the component (e) ethylene / α-olefin copolymer rubber, a known polymerization method using a known olefin polymerization catalyst is used. For example, a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method and the like using a Ziegler-Natta catalyst, a complex catalyst such as a metallocene complex or a nonmetallocene complex, and the like can be mentioned.

  Commercially available ethylene / α-olefin copolymer rubber of component (e) can also be used. For example, JSR EPR manufactured by JSR, Mitsui EPT manufactured by Mitsui Chemicals, Espren (registered trademark) manufactured by Sumitomo Chemical Co., Keltan (registered trademark) manufactured by LANXESS, Engage (registered trademark) manufactured by Dow, Tuffer manufactured by Mitsui Chemical (Trademarks) etc. can be selected and used.

[Component (f): Softener for hydrocarbon rubber]
The thermoplastic elastomer composition of the present invention softens the obtained thermoplastic elastomer composition, increases flexibility and elasticity, and improves the workability and fluidity of the obtained thermoplastic elastomer composition by the following components ( It is preferable to include f).
Component (f): Hydrocarbon softener

Hydrocarbon rubber softeners include mineral oil softeners and synthetic resin softeners, and mineral oil softeners are preferred from the standpoint of affinity with other components. Mineral oil softeners are generally a mixture of aromatic hydrocarbons, naphthenic hydrocarbons and paraffinic hydrocarbons, with paraffinic oils in which 50% or more of all carbon atoms are paraffinic hydrocarbons, Those in which 30 to 45% of all carbon atoms are naphthenic hydrocarbons are called naphthenic oils, and those in which 35% or more of all carbon atoms are aromatic hydrocarbons are called aromatic oils. Among these, it is preferable to use paraffinic oil for the thermoplastic elastomer composition of the present invention. The component (f), the hydrocarbon rubber softener, may be used alone or in combination of two or more.

  The kinematic viscosity at 40 ° C. of the softener for hydrocarbon rubber is preferably 20 centistokes or more, more preferably 50 centistokes or more, and on the other hand, it is preferably 800 centistokes or less. Preferably it is 600 centistokes or less. In addition, the flash point (COC method) of the hydrocarbon rubber softener is preferably 200 ° C. or higher, and more preferably 250 ° C. or higher.

[Component (g): Crosslinking aid]
When producing the thermoplastic elastomer composition of the present invention, it is preferable to perform dynamic heat treatment in the presence of the following component (g) together with the component (d).
Component (g): Crosslinking aid

  Examples of the crosslinking aid for component (g) include peroxide aids such as sulfur, p-quinonedioxime, p-dinitrosobenzene, 1,3-diphenylguanidine; divinylbenzene, triallyl cyanurate, Polyfunctional vinyl compounds such as triallyl isocyanurate and diallyl phthalate; ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) Examples include polyfunctional (meth) acrylate compounds such as acrylate. These may be used alone or in combination of two or more.

[Combination ratio]
The blending ratio of the raw materials of the thermoplastic elastomer composition of the present invention will be described below. The thermoplastic elastomer composition of the present invention is obtained by dynamic heat treatment of a composition containing components (a) to (c) in the presence of component (d). The blending ratio means the preparation amount before performing the dynamic heat treatment.

  The content of component (a) is 10% by weight or more, preferably 15% by weight or more, from the viewpoint of flexibility, with respect to the total amount of component (a), component (b) and component (c), More preferably, it is 20% by weight. Further, from the viewpoint of moldability, it is 85% by weight or less, preferably 80% by weight or less, and more preferably 75% by weight or less.

  The content of the component (b) is 5% by weight or more, preferably 7% by weight or more with respect to the total amount of the component (a), the component (b) and the component (c) from the viewpoint of moldability. More preferably, it is 10% by weight. On the other hand, from the viewpoint of flexibility, it is 60% by weight or less, preferably 50% by weight or less, and more preferably 45% by weight or less.

  The content of component (c) is 5% by weight or more, preferably 7% by weight or more, from the viewpoint of easy breakability, with respect to the total amount of component (a), component (b) and component (c). More preferably, it is 10% by weight or more. On the other hand, from the viewpoint of flexibility, it is 60% by weight or less, preferably 50 parts by weight or less, and more preferably 45% by weight or less.

The amount of component (d) used is preferably 0.05 parts by weight or more in order to allow the crosslinking reaction to proceed sufficiently with respect to 100 parts by weight of component (a), component (b) and component (c) in total. More preferably, it is 0.1 weight part or more, More preferably, it is 0.3 weight part or more. On the other hand, from the viewpoint of controlling the crosslinking reaction, it is preferably 5.0 parts by weight or less, more preferably 4.0 parts by weight or less, and still more preferably 3.0 parts by weight or less.

  The content of the component (e) is preferably 1 part by weight or more, more preferably 10 parts by weight from the viewpoint of flexibility with respect to 100 parts by weight of the total of the components (a), (b) and (c). Part or more, more preferably 20 parts by weight or more, and particularly preferably 30 parts by weight or more. On the other hand, from the viewpoint of moldability, it is preferably 200 parts by weight or less, more preferably 150 parts by weight or less, still more preferably 120 parts by weight or less, and particularly preferably 100 parts by weight or less.

  The content of component (f) is preferably 1 part by weight or more, more preferably 10 parts by weight or more, and still more preferably 20 parts per 100 parts by weight in total of component (a), component (b) and component (c). Part by weight or more, particularly preferably 30 parts by weight or more, on the other hand, preferably 200 parts by weight or less, more preferably 150 parts by weight or less, still more preferably 120 parts by weight or less, particularly preferably 100 parts by weight or less. When the content of the component (f) is not less than the above lower limit value, flexibility and molding processability tend to be good, and when it is not more than the above upper limit value, it tends to be easy to mold.

  The amount of component (g) used is usually in the range of 0.01 to 4.0 parts by weight, preferably 0 with respect to 100 parts by weight in total of component (a), component (b) and component (c). 0.05 to 3.0 parts by weight. When it is at least the above lower limit value, the effect of using the crosslinking aid is obtained, and it is preferably at most the upper limit value in terms of cost.

  The weight ratio of component (a) to component (e) ([weight of component (a)]: [weight of component (e)]) of the thermoplastic elastomer composition is preferably 1: 0.3 to 1:10. More preferably, it is 1: 0.4-1: 8, More preferably, it is 1: 0.5-1: 5, Most preferably, it is 1: 0.7-1: 4. When the weight ratio is in the above range, it tends to be particularly excellent in breakability.

[Other ingredients]
In the olefinic thermoplastic elastomer composition of the present invention, in addition to the components (a) to (g), other components can be blended depending on the purpose within a range not impairing the effects of the present invention.

  Examples of other components include fillers, antioxidants, heat stabilizers, light stabilizers, UV absorbers, neutralizers, lubricants, antifogging agents, antiblocking agents, slip agents, dispersants, colorants, Various additives such as a flame retardant, an antistatic agent, a conductivity imparting agent, a metal deactivator, a molecular weight adjusting agent, an antibacterial agent, an antifungal material, and a fluorescent brightening agent, components (a) to (c) and components ( Examples include thermoplastic resins other than e), elastomers other than components (a) to (c) and component (e), and the like. Any of these may be used alone or in combination.

  Examples of the filler include glass fiber, hollow glass sphere, carbon fiber, talc, calcium carbonate, mica, potassium titanate fiber, silica, metal soap, titanium dioxide, and carbon black. When using a filler, it is normally used in 0.1-50 weight part with respect to a total of 100 weight part of component (a)-(c).

  Antioxidants include phenolic antioxidants, phosphite antioxidants, thioether antioxidants, and the like. When using antioxidant, it is normally used in 0.01-3.0 weight part with respect to a total of 100 weight part of component (a)-(c).

Examples of thermoplastic resins other than components (a) to (c) and component (e) include polyphenylene ether resins; polyamide resins such as nylon 6 and nylon 66; polyester resins such as polyethylene terephthalate and polybutylene terephthalate. Polyoxymethylene resins such as polyoxymethylene homopolymers and polyoxymethylene copolymers; polymethylmethacrylate resins and polyolefin resins (but those other than components (a) to (c) and component (e)) Etc.). Examples of the elastomers other than the components (a) to (c) and the component (e) include styrene elastomers such as styrene / butadiene copolymer rubber and styrene / isoprene copolymer rubber; polyester elastomers; Can be mentioned.

[Method for producing thermoplastic elastomer composition]
The thermoplastic elastomer composition of the present invention is obtained by subjecting a composition containing a predetermined amount of component (a), component (b) and component (c) to dynamic heat treatment in the presence of component (d). .

  In the present invention, “dynamic heat treatment” means kneading in a molten state or a semi-molten state. This dynamic heat treatment is preferably carried out by melt kneading. As a mixing and kneading apparatus therefor, for example, a non-open Banbury mixer, a mixing roll, a kneader, a twin screw extruder, or the like is used. Among these, it is preferable to use a twin screw extruder. As a preferable aspect of the manufacturing method using this twin-screw extruder, each component is supplied to the raw material supply port (hopper) of the twin-screw extruder which has a some raw material supply port, and dynamic heat processing is performed.

  The temperature at which the dynamic heat treatment is performed is usually 80 to 300 ° C, preferably 100 to 250 ° C. Moreover, the time which performs dynamic heat processing is 0.1 to 30 minutes normally.

In the case where the thermoplastic elastomer composition of the present invention is subjected to dynamic heat treatment by a twin screw extruder, the barrel radius R (mm), screw rotation speed N (rpm) and discharge amount Q (kg / hour) of the twin screw extruder. ) Is preferably extruded while maintaining the relationship of the following formula, and more preferably extruded while maintaining the relationship of the following formula (2).
2.6 <NQ / R ³ <22.6 (1)
3.0 <NQ / R ³ <20.0 (2)

  It is efficient for the thermoplastic elastomer composition that the relationship among the barrel radius R (mm), screw rotation speed N (rpm) and discharge rate Q (kg / hour) of the twin screw extruder is larger than the lower limit value. It is preferable for manufacturing. On the other hand, it is preferable that the relationship is smaller than the above upper limit value because it suppresses heat generation due to shearing and makes it difficult for foreign matters that cause poor appearance to occur.

[Physical properties]
The thermoplastic elastomer composition of the present invention is excellent in flexibility and excellent in breakability in a wide temperature range from low temperature to high temperature.

  In the present invention, the value of tear strength at break measured by the method shown in the examples below is used as an index of easy breakability. Since it is preferable to have excellent breakability while maintaining the strength, the value of tear strength at break is preferably less than 25.0 MPa at -25 ° C, more preferably less than 20.0 MPa, More preferably, it is less than 15.0 MPa, while 5.0 Ma or more is preferred. Further, at 23 ° C., it is preferably less than 5.5 MPa, more preferably less than 5.0 MPa, still more preferably less than 4.5 MPa, and on the other hand, it is preferably 2.0 Ma or more. Furthermore, at 85 ° C., it is preferably less than 2.7 MPa, more preferably less than 2.4 MPa, still more preferably less than 2.1 MPa, and on the other hand, it is preferably 0.5 Ma or more.

  The thermoplastic elastomer composition of the present invention has a melt flow rate (MFR) at a temperature of 230 ° C. and a measurement load of 49 N in accordance with JIS K7210. It is preferable that If the MFR of the thermoplastic elastomer composition is 0.5 g / 10 min or more, the fluidity tends to be good, and if it is 200 g / 10 or less, it is preferable because burrs and the like during molding can be easily suppressed. From the viewpoint of fluidity, it is preferably 1.0 g / 10 min or more, more preferably 5.0 g / 10 min or more, and even more preferably 10 g / 10 min or more. From the viewpoint of suppressing the MFR, the MFR of the thermoplastic elastomer composition is more preferably 150 g / 10 min or less, still more preferably 120 g / 10 min or less.

  The thermoplastic elastomer composition of the present invention preferably has a hardness duro A value of 50 to 95, more preferably 55 to 90. The method for measuring the hardness duro A is shown in the examples below.

[Molded products / uses]
The thermoplastic elastomer composition of the present invention can be formed into a molded body by various molding methods such as injection molding, extrusion molding, hollow molding, compression molding, etc., which are usually used for thermoplastic elastomer compositions. Of these, injection molding and extrusion molding are preferred. Moreover, it can also be set as the molded object which performed secondary processing, such as lamination molding and thermoforming, after performing these shaping | molding.

  Since the thermoplastic elastomer composition of the present invention has the above-mentioned effects, it is suitable as a skin for an instrument panel and particularly suitable as a skin for an instrument panel provided with an airbag mechanism. The use of the thermoplastic elastomer composition of the present invention is not limited to the skin for instrument panels, but other automotive parts (weather strips, ceiling materials, interior sheets, bumper moldings, side moldings, air spoilers, air ducts). Hoses, various packings, etc.), civil engineering / building materials parts (water-stopping materials, joint materials, window frames, etc.), sports equipment (golf clubs, tennis racket grips, etc.), industrial parts (hose tubes, gaskets, etc.), Use in a wide range of fields such as home appliance parts (hose, packing, etc.), medical parts (medical containers, gaskets, packing, etc.), food parts (containers, packing, etc.), medical equipment parts, electric wires, sundries, etc. Can do.

  EXAMPLES Hereinafter, although the content of this invention is demonstrated more concretely using an Example, this invention is not limited by a following example, unless the summary is exceeded. The values of various production conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiment of the present invention, and preferred ranges are the upper limit or lower limit values described above, and It may be a range defined by a combination of values of the examples or values between the examples.

<Raw materials>
The raw materials used in the following examples and comparative examples are as follows.

[Component (a)]
(A-1): Oil-extended ethylene / propylene / ethylidene norbornene copolymer rubber (Mooney viscosity ML (1 + 4) (125 ° C.): 65, ethylene content: 66 wt%, ethylidene norbornene content: 4.5 wt% ), Polypropylene (PP) equivalent weight average molecular weight: 647,000, containing 100 parts by weight of a paraffinic rubber softener per 100 parts by weight of ethylene / propylene / ethylidene norbornene copolymer rubber. )

[Component (b)]
(B-1): Polypropylene (MFR: 1.9 g / 10 min (measurement conditions: 230 ° C., load 21.2 N)) FY6H manufactured by Nippon Polypro Co., Ltd.
(B-2): Polypropylene (MFR: 40 g / 10 min (measurement conditions: 230 ° C., load 21.2 N)) / SA04M manufactured by Nippon Polypro Co., Ltd.

[Component (c)]
(C-1): Low density polyethylene (MFR: 2 g / 10 min, measurement conditions: 190 ° C., load 21.2 N, density: 0.919 g / cm ³ , obtained by high pressure method) / Japan LF405 manufactured by Polyethylene Corporation
(C-1) (for comparative example): high density polyethylene (MFR: 0.35 g / 10 min, measurement conditions: 190 ° C., load 21.2 N, density: 0.953 g / cm ³ ) / manufactured by Nippon Polyethylene HB330
(C-2) (for comparative example): Linear low density polyethylene (MFR: 1 g / 10 min, measurement conditions: 190 ° C., load 21.2 N, density: 0.921 g / cm ³⁾ , obtained by a gas phase method / Saudi Petrochemicals FC18NJ

[Component (d)]
(D-1): A mixture of 40% by weight of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 60% by weight of calcium carbonate / Kayahexa AD40C manufactured by Kayaku Akzo Corporation

[Component (e)]
(E-1): Ethylene / propylene / ethylidene norbornene copolymer rubber (Mooney viscosity ML (1 + 4) (125 ° C.): 57, ethylene content: 66 wt%, ethylidene norbornene content: 4.5 wt%), polypropylene (PP) weight average molecular weight: 223,000. )

[Component (f)]
(F-1): Paraffinic rubber softener (kinematic viscosity at 40 ° C .: 95.54 cSt (centistokes), pour point: −15 ° C., flash point: 272 ° C.) / PW90 manufactured by Idemitsu Kosan Co., Ltd.

[Ingredient (g)]
(G-1): Mixture of 60% by weight divinylbenzene and 40% ethylvinylbenzene

<Evaluation method>
Evaluation methods of thermoplastic elastomer compositions in the following examples and comparative examples are as follows.

(1) Melt flow rate (MFR)
Measurement was performed at a measurement temperature of 230 ° C. and a measurement load of 49 N by a method based on the standard of JIS K7210.

(2) Hardness duro A
In-line screw type injection molding machine (“IS130” manufactured by Toshiba Machine Co., Ltd.) is injection-molded under the conditions of injection pressure 50 MPa, cylinder temperature 220 ° C., mold temperature 40 ° C., 120 mm wide, 80 mm long, 2 mm thick sheet Got. Using this, the hardness was measured according to JIS K6253 (JIS-A).

(3) Tensile strength at the time of cutting: Laboplast mill (“4C150” manufactured by Toyo Seiki Co., Ltd.) An extruded sheet having a thickness of 0.5 mm was prepared under conditions of 180 ° C., punched with a test piece-shaped dumbbell, and used for measurement. . JIS
Reference was made to K6251 (JIS-3 dumbbell, tensile speed 500 mm / min), and measurement was carried out in a thermostatic bath at −20 ° C., 23 ° C., and 85 ° C. The tensile strength at the time of cutting was judged to be better as the value was smaller, and was evaluated according to the following criteria.
(-25 ° C)
A: 5.0 MPa or more and less than 15.0 MPa ○: 15.0 MPa or more and less than 20.0 MPa Δ: 20.0 MPa or more and less than 25.0 MPa X: 25.0 MPa or more or less than 5.0 MPa (23 ° C.)
A: 2.0 MPa or more and less than 4.5 MPa ○: 4.5 MPa or more and less than 5.0 MPa Δ: 5.0 MPa or more and less than 5.5 MPa x: 5.5 MPa or more or less than 2.0 MPa (85 ° C.)
A: 0.5 MPa or more and less than 2.1 MPa ○: 2.1 MPa or more and less than 2.4 MPa Δ: 2.4 MPa or more and less than 2.7 MPa x: 2.7 MPa or more or less than 0.5 MPa

<Example / comparative example>
[Example 1]
Component (a-1) 39% by weight, Component (b-1) 37% by weight, Component (d-1) 0.7 parts by weight, Component (e-1) 66 parts by weight, (g-1) 0.7 Part by weight, 1.2 parts by weight of Irganox (registered trademark) 1010 as an antioxidant and 5 parts by weight of calcium carbonate as a filler were blended in a Henschel mixer for 1 minute. Using the same-direction twin screw extruder (Nippon Steel Works “TEX30”, L / D = 46, number of cylinder blocks: 12), each raw material component is supplied from the supply port, and a total of 20 kg / h is discharged, and the upstream part The temperature of the downstream portion was raised in the range of 110 to 180 ° C., melted and kneaded, and pelletized to produce a thermoplastic elastomer composition. The evaluation results are shown in Table-1.

[Examples 2 to 8 and Comparative Examples 1 to 4]
Except having changed the compounding composition as shown in Table 1, it implemented like Example 1 and obtained the pellet of the thermoplastic elastomer composition. About the obtained thermoplastic elastomer composition, the result of having implemented evaluation similar to Example 1 is shown in Table-1.

[Evaluation results]
As shown in Table 1, it can be seen that Examples 1 to 7 are excellent in easy breakability in each temperature region of −20 ° C., 23 ° C., and 85 ° C. On the other hand, Comparative Examples 1 and 2 are examples in which high-density polyethylene (HEPE) or linear low-density polyethylene (LLEPE) is used in place of the component (c) of the present invention, but breakability at 23 ° C and 85 ° C. Was bad. Comparative Example 3 was an example in which component (c) was not used, and Comparative Example 4 was an example in which component (a) was not used, but the ruptureability was poor in each temperature range. .

  The thermoplastic elastomer composition of the present invention is excellent in flexibility and excellent in breakability in a wide temperature range from low temperature to high temperature. For this reason, it is suitable as a skin for an instrument panel, and particularly suitable as a skin for an instrument panel provided with an airbag mechanism. The use of the thermoplastic elastomer composition of the present invention is not limited to the skin for instrument panels, but other automotive parts (weather strips, ceiling materials, interior sheets, bumper moldings, side moldings, air spoilers, air ducts). Hoses, various packings, etc.), civil engineering / building materials parts (water-stopping materials, joint materials, window frames, etc.), sports equipment (golf clubs, tennis racket grips, etc.), industrial parts (hose tubes, gaskets, etc.), Use in a wide range of fields such as home appliance parts (hose, packing, etc.), medical parts (medical containers, gaskets, packing, etc.), food parts (containers, packing, etc.), medical equipment parts, electric wires, sundries, etc. Can do.

Claims (13)

The following component (a), component (b) and component (c) are included, and component (a) is 10 to 85% by weight with respect to the total amount of component (a), component (b) and component (c), component ( b) A thermoplastic elastomer composition obtained by dynamically heat-treating a composition containing 5 to 60% by weight and component (c) 5 to 60% by weight in the presence of the following component (d).
Component (a): Oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber component (b): Polypropylene resin component (c): Density produced by high pressure method is 0.910 to 0.940 g / cm ³ polyethylene component (d): organic peroxide   The thermoplastic elastomer composition according to claim 1, wherein in the component (a), the weight average molecular weight of the ethylene / α-olefin / non-conjugated diene copolymer rubber part is 300,000 or more and 1,000,000 or less. The following component (e) is included, and the content thereof is 1 to 200 parts by weight with respect to a total of 100 parts by weight of the components (a) to (c) of the thermoplastic elastomer composition. Thermoplastic elastomer composition.
Component (e): Non-oil-extended ethylene / α-olefin copolymer rubber   The thermoplastic elastomer composition according to claim 3, comprising at least non-oil-extended ethylene / α-olefin / non-conjugated diene copolymer rubber as component (e) of the thermoplastic elastomer composition.   The thermoplastic elastomer composition according to claim 3 or 4, wherein the component (e) has a weight average molecular weight of 100,000 or more and less than 300,000.   The thermoplastic elastomer composition according to any one of claims 3 to 5, wherein a weight ratio of the component (a) to the component (e) is 1: 0.3 to 1:10. The composition according to any one of claims 1 to 6, comprising the following component (f) and having a content of 0.1 to 200 parts by weight with respect to a total of 100 parts by weight of the components (a) to (c). The thermoplastic elastomer composition as described.
Component (f): Hydrocarbon softener The thermoplastic elastomer composition according to any one of claims 1 to 7, obtained by dynamic heat treatment in the presence of the following component (g).
Component (g): Crosslinking aid   The molded object formed by shape | molding the thermoplastic elastomer composition of any one of Claims 1 thru | or 8.   The molded product according to claim 9, which is formed by injection molding.   The molded product according to claim 9, which is formed by extrusion molding.   A skin for an instrumental panel comprising the thermoplastic elastomer composition according to any one of claims 1 to 8.   The skin for an instrumental panel according to claim 12, comprising an airbag mechanism.