JPH11166075A - Thermoplastic elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer having the same compression permanent set as those of vulcanized rubbers without deteriorating moldability and capable of being applied to various kinds of uses requiring wide coloration freedom and long period reliability. SOLUTION: This thermoplastic elastomer composition is obtained by dynamically thermally treating a mixture comprising (a) 100 pts.wt. of an unsaturated double bond-containing rubber, (b) 10-150 pts.wt. of an olefinic resin, (c) 0.1-30 pts.wt. of a silicone compound having two or more SiH groups in the molecule, (d) 0.0001-0.02 pt.wt. of a hydrosilylation platinic catalyst, (e) 0.05-2 pts.wt. of an organic peroxide, and (f) 10-300 pts.wt. of a paraffinic oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a thermoplastic elastomer composition produced by crosslinking a rubber component by a hydrosilylation reaction. More specifically, the present invention relates to a thermoplastic elastomer having excellent compression set and excellent long-term reliability such as weather resistance.

[0002]

2. Description of the Related Art In recent years, thermoplastic elastomers which do not require vulcanization and have the same excellent moldability as thermoplastic resins have been used in automobile parts, home electric parts, wire covering materials, medical parts, miscellaneous goods, Used in fields such as footwear. Examples of thermoplastic elastomers include JP-B-53-2
No. 1021 discloses a composition in which a monoolefin copolymer rubber and a polyolefin resin are partially crosslinked by melt-kneading using an organic peroxide as a rubber crosslinking aid. Such a thermoplastic elastomer cannot be used for a wide range of applications because the monoolefin copolymer rubber is partially crosslinked, and therefore has insufficient oil resistance and shape recovery at high temperatures. In addition, radicals generated from the organic peroxide used for crosslinking cause the polymer chain to be cut, resulting in a decrease in mechanical strength.

Further, Japanese Patent Publication No. 58-46138 discloses that in order to solve such a drawback, a heat-reactive alkylphenol resin is used as a crosslinking agent and only a monoolefin copolymer rubber is preferentially crosslinked. Are listed. That is, a thermoplastic elastomer in which EPDM rubber is selectively crosslinked with a phenolic crosslinking agent in a thermoplastic resin is described. The thermoplastic elastomer obtained by such a production method has improved oil resistance and shape recovery under high temperatures because the rubber component is completely crosslinked, but has poor light discoloration resistance due to the use of an alkylphenol resin, Automotive parts that require a high degree of freedom in toning,
Not suitable for applications such as home appliances. No. 4
803244 discloses that by using an organosiloxane compound as a cross-linking agent, a rubber having an unsaturated double bond can be selectively cross-linked in an olefin-based resin without decomposition of a polymer chain. The thermoplastic elastomer obtained by this method is excellent in light discoloration resistance and relatively excellent in shape recovery, but the shape recovery is not yet sufficient for use in vulcanized rubber substitutes such as weather strips. .

[0004]

SUMMARY OF THE INVENTION In view of the above, the present invention is required to have a compression set equal to that of vulcanized rubber, a wide degree of freedom in coloring, hygiene, and long-term reliability without impairing moldability. An object of the present invention is to provide a thermoplastic elastomer applicable to various applications.

[0005]

Means for Solving the Problems Achieving this difficult task of having a compression set comparable to that of a vulcanized rubber, and having a wide degree of freedom in coloring, sanitary properties, and long-term reliability without impairing moldability. As a result of conducting various investigations, a rubber containing unsaturated double bonds in a polyolefin resin was converted to a silicone-based compound having two or more SiH groups in the molecule using a platinum-based hydrosilylation catalyst and an organic peroxide as a catalyst. The present inventors have found that an elastomer having excellent compression set and long-term reliability can be obtained without impairing the moldability by dynamically crosslinking, and the present invention has been completed. That is, the present invention provides an unsaturated double bond-containing rubber (a), a polyolefin-based resin (b), a silicone-based compound having two or more SiH groups in a molecule (c), and a platinum-based hydrosilylation catalyst (d). And a thermoplastic elastomer composition obtained by dynamically heat-treating a mixture containing at least an organic peroxide (e).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Unsaturated Double Bond-Containing Rubber The unsaturated double bond-containing rubber (a) used in the present invention comprises:
In general, commercially available rubbers containing an unsaturated double bond in the main chain and / or the side chain are shown. Preferably, ethylene-
α-olefin-non-conjugated diene copolymer (a-1), vinyl aromatic compound-conjugated diene copolymer and its partially double hydrogenated unsaturated double bond copolymer (a-2), conjugated It is at least one member selected from diene copolymers, copolymers (a-3) partially hydrogenated with unsaturated double bonds thereof, and butyl rubber (a-4).

As the ethylene-α-olefin-non-conjugated diene copolymer rubber (a-1), various olefin rubbers composed of ethylene, α-olefin and non-conjugated diene can be used. α-olefin has 3 to 1 carbon atoms
5 is preferable, and propylene is particularly preferable from the viewpoint of easy availability. As the non-conjugated diene, dicyclopentadiene (DCPD), 5- (2-methyl-2-
Butenyl) -2-norbornene (MBN), 5-methylene-2-norbornene (MNB), 5-ethylidene-2
-Norbornene (ENB), methyltetrahydroindene (MTHI), and 1,4-hexadiene (HD) are preferably used. Among these, DCPD, ENB, and HD are preferable from the viewpoint of easy availability, and ENB is particularly preferable from the viewpoint of crosslinkability. Therefore, the ethylene-α-olefin-non-conjugated diene copolymer rubber used in the present invention is most preferably an ethylene-propylene-ethylidene norbornene copolymer.

The ethylene / α-olefin ratio of such a copolymer rubber is preferably 5% by weight in order to obtain preferable rubber elasticity.
0/50 to 90/10, more preferably 60/40 to
80/20. The Mooney viscosity [ML _{1 + 4} (125 ° C.)] of the rubber used in the present invention is 10 to 120, preferably 40 to 100. When the Mooney viscosity of the rubber is less than 10, the molecular weight of the crosslinked rubber tends to be small and the compression set tends to be large because the molecular weight is very small. On the other hand, if the Mooney viscosity is more than 120, the moldability is remarkably reduced, which is not preferable. In addition, such a rubber component is melt-kneaded in advance with paraffin oil (oil extension).
Those having an apparent Mooney viscosity adjusted to 120 or less are commercially available, and can be used. The iodine value of the rubber is an index of reactivity, and the larger the value, the higher the activity. The rubber type used in the present invention preferably has a high activity of 10 to 30, especially 15 to 30.

The vinyl aromatic compound-conjugated diene copolymer and the copolymer (a-2) in which the unsaturated double bond is partially hydrogenated include styrene-butadiene block copolymer and styrene-isoprene block. Copolymers, styrene-butadiene random copolymers, styrene-isoprene random copolymers, and partially hydrogenated compounds thereof are exemplified. The hydrogenation rate of the carbon-carbon double bond is
If it is 95% or more, it is difficult to sufficiently perform crosslinking. Examples of the conjugated diene copolymer and the copolymer (a-3) in which the unsaturated double bond is partially hydrogenated include polybutadiene, polyisoprene, and natural rubber.

Olefin Resin The olefin resin (b) used in the present invention includes:
Polyethylene, polypropylene and ethylene-α-olefin copolymer are suitable. As polyethylene, high density type (HDPE), medium density type (MDPE), low density type (LDPE), linear low density type (L-LDPE)
And the like. The MFR of the polyethylene is preferably 0.1 to 50 g / 10 min, more preferably 0.5 to 50 g / 10 min.
20 g / 10 min, most preferably 1 to 15 g / 10
min. MFR of polyethylene is 0.1g / 10
If it is smaller than min, the extrudability tends to deteriorate.

Examples of propylene include isotactic polypropylene and random or block copolymers of propylene and other small amounts of α-olefins, such as propylene-ethylene copolymers and propylene-1-hexene copolymers. Can be mentioned. In addition, poly 4-
Methyl-1-pentene, polybutene-1 and the like can also be used. MFR when using isotactic polypropylene or its copolymer is 0.1 to 50 g / 10
min, especially those in the range of 0.5 to 30 g / 10 min can be suitably used.

The ethylene-α-olefin copolymer is preferably an α-olefin having 3 to 15 carbon atoms. Specific α-olefins include propylene,
Butene-1, pentene-1, hexene-1, octene-
1,4-methylpentene-1,4-methylhexene-
1,4,4-dimethylpentene-1, nonene-1, decene-1, undecene-1, dodecene-1, 1-tridecene, 1-tetradecene, 1-pentadecene, etc., and particularly propylene, butene-1, Hexene-1 and octene-1 are preferred. That is, as the ethylene-α-olefin copolymer used in the present invention, ethylene-α-olefin copolymer
Preferred are a propylene copolymer, an ethylene-butene copolymer, an ethylene-hexene copolymer, and an ethylene-octene copolymer. The composition ratio of ethylene / α-olefin is 95
/ 5 to 50/50, preferably 90/10 to 70/30
Is more preferable. The MFR is 0.5 to 50
g / 10 min is preferable. These polyolefin resins may be used alone or in combination of two or more.

The compounding amount of the olefin resin (b) is 10 to 1 with respect to 100 parts by weight of the unsaturated double bond-containing rubber (a).
It is 50 parts by weight, preferably 15 to 100 parts by weight, most preferably 20 to 70 parts by weight. If the amount exceeds 150 parts by weight, the compression set of the obtained elastomer composition tends to deteriorate, while if the amount is less than 10 parts by weight, processability tends to deteriorate.

Silicone-Based Crosslinking Agent Having SiH Group The silicone-based compound (c) having two or more SiH groups in a molecule used in the present invention can selectively use an unsaturated double bond-containing rubber in an olefin resin. It is a crosslinking agent for crosslinking. The platinum-based hydrosilylation catalyst (d) and the organic peroxide (e) are cross-linking catalysts used for causing this cross-linking reaction to proceed at a practical rate. An elastomer which accelerates and has excellent compression set is obtained. Crosslinking with a silicone compound having two or more SiH groups in the molecule means that
The method uses a selective addition reaction (hydrosilylation) to an unsaturated double bond in a rubber component by an iH group. The crosslinking agent used here needs to have two or more SiH groups in one molecule in order to be added to two or more molecules of rubber.

Preferred examples of such a silicon-based crosslinking agent include the following organosiloxanes such as cyclic organohydrogensiloxane (I), linear organohydrogensiloxane (II) and tetrahedral organohydrogensiloxane (III). Examples include compounds having a structure and compounds derived therefrom. In order to increase the crosslink density of the rubber, it is preferable that the number of SiH groups in the silicon-based crosslinker is large. Among these silicon-based crosslinking agents, linear polyorganohydrogensiloxanes (II) having 5 or more SiH groups in the molecule are preferred, more preferably 10 or more, and most preferably 15 or more. further,
Preferred crosslinking agents include SiH such as the following II-
A linear organohydrogensiloxane composed only of a group-containing unit is exemplified.

[0016]

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[0017]

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[0018]

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[Wherein, R (R ′) is independently an alkyl group or an alkoxyl group having 1 to 24 carbon atoms; one or more selected from a phenyl group, an aryl group and an aryloxy group. A substituent, preferably a methyl group. n is 2 to 100, preferably 5 to 8
0 and m are integers of 1 to 100, and s is an integer of 0 to 2. R of each substituent may be the same or different. ]

In producing the elastomer, the amount of the silicone-based crosslinking agent is preferably 0.5 to 30 parts by weight, more preferably 1 to 30 parts by weight, per 100 parts by weight of the rubber component.
20 parts by weight. If the amount of the crosslinking agent is less than 0.5 part by weight, sufficient crosslinking may not be obtained, and the rubber properties of the elastomer may not be sufficient. On the other hand, when the compounding amount of the crosslinking agent is 3
If the amount is more than 0 parts by weight, the effect hardly increases and bleeding of the crosslinking agent may occur.

Platinum-based hydrosilylation catalyst The platinum-based hydrosilylation catalyst (d) is not particularly limited as long as it exhibits a catalytic action in the hydrosilylation reaction, but platinum vinylsiloxane complex (Karlstead catalyst) And a platinum compound such as chloroplatinic acid and a complex are preferred. Among them, a complex of platinum and a siloxane compound containing a vinyl group, such as a platinum / divinyltetramethyldisiloxane complex, is particularly preferred.

In order to highly disperse these platinum-based hydrosilylation catalysts in a material, a method in which a composition alone or a solution dissolved in a liquid is kneaded in a resin in advance and used as a masterbatch, or supported on a solid component such as an inorganic filler. It is preferable to use the method. As the resin to be kneaded, an olefin resin is preferable, and particularly, polyethylene, polypropylene, and an ethylene-α-olefin copolymer are preferable. As the solid component to be supported, a carrier having an adsorption ability is used, for example, calcium carbonate, carbon black, talc, mica, barium sulfate, natural silicic acid, synthetic silicic acid (white carbon), and inorganic fillers such as titanium oxide. Of these, it is preferable to use synthetic silicic acid. Known methods may be used for preparing the catalyst supported on these carriers.

The platinum-based hydrosilylation catalyst is preferably used in an amount of 0.0001 to 0.02 parts by weight, more preferably 0.0005 to 0.02 parts by weight, based on 100 parts by weight of the rubber component.
1 part by weight. If the amount is less than 0.0001 part by weight, the reaction rate becomes slow and the time required for sufficient crosslinking becomes long. On the other hand, if the amount exceeds 0.02 parts by weight, the effect is hardly increased, and the cost is likely to increase because the platinum-based catalyst is expensive.

[0024] The combined use of an organic peroxide with an organic peroxide a platinum-based hydrosilylation catalyst, compression set of the resulting thermoplastic elastomer is improved. Further, the amount of expensive platinum-based hydrosilylation catalyst can be reduced without impairing rubber properties such as compression set. Examples of the organic peroxide (e) include dicumyl peroxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, di-t-butyl peroxide, t-butylcumyl peroxide, Benzoyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butylperoxypiparate, t-butylperoxy-2-ethylexanoate and the like can be used. . The amount of the organic peroxide is 0.1 to 100 parts by weight of the rubber component.
It is 0.5 to 2 parts by weight, preferably 0.1 to 1 part by weight.
If the amount is less than 0.05 part by weight, the effect of using the organic peroxide will not be exhibited, and if it exceeds 2 parts by weight, there may be a case where the moldability and the mechanical properties decrease.

Paraffinic oil In the present invention, a paraffinic oil may be added as necessary for the purpose of adjusting the hardness of the obtained composition and giving flexibility. As the paraffin oil used,
Kinetic viscosity at 37.8 ° C is 20 to 500 cs.
t, pour point is -10 to -15 ° C and flash point is 170 to
Those exhibiting 300 ° C. are preferred. The preferred blending amount of the paraffinic oil is 10 to 300 parts by weight, more preferably 20 to 1 part by weight, per 100 parts by weight of the rubber component.
50 parts by weight. If the amount is more than 300 parts by weight, the softener tends to bleed out, the final product may be tacky, and the mechanical properties tend to deteriorate.

Other additives In the elastomer of the present invention, if necessary,
You may mix | blend an inorganic filler. This inorganic filler not only has the advantage of reducing the product cost as a bulking agent, but also has the advantage of giving a positive effect on quality improvement (heat-resistant shape retention, flame retardancy, etc.). Such inorganic fillers include, for example, calcium carbonate, carbon black,
Talc, magnesium hydroxide, mica, barium sulfate,
There are natural silicic acid, synthetic silicic acid (white carbon), titanium oxide and the like, and as the carbon black, channel black, furnace black and the like can be used. Of these inorganic fillers, talc and calcium carbonate are economically advantageous and preferred.

Further, various additives can be added as required. Examples of additives include nucleating agents, outer lubricants, inner lubricants, hindered amine light stabilizers, hindered phenolic antioxidants, coloring agents, flame retardants, silicone oils (organosiloxane, silane coupling agents, etc.) ) Can be used. Further, other thermoplastic resins such as polyester, polyamide, and thermoplastic polyurethane and various compatibilizers can be blended.

Production Method The unsaturated double bond-containing rubber (a) of the present invention, a polyolefin resin (b), a silicone compound having two or more SiH groups in its molecule (c), a platinum hydrosilylation catalyst ( As a method of mixing d) and the organic peroxide (e) and performing a heat treatment dynamically, any of the known methods used in the production of ordinary resin compositions and rubber compositions can be employed. The dynamic heat treatment is basically a mechanical melt-kneading method, and a single-screw extruder, a twin-screw extruder, a Banbury mixer, various kneaders, a Brabender, or the like can be used for such a treatment. It is a screw extruder. The order of addition of each component in the dynamic heat treatment is not particularly limited,
For example, an addition method may be adopted in which components other than the catalyst are melt-kneaded in advance, and further a platinum-based hydrosilylation catalyst or a catalyst component of an organic peroxide is added and melt-kneaded.

The thermoplastic elastomer composition of the present invention, which can be appropriately selected from a melt kneading temperature of 160 ° C. to 300 ° C. and a shear rate of 100 to 5000 / sec, can be prepared by using a known thermoplastic resin molding machine. It can be shaped into a desired shape. Such molding includes injection molding, extrusion molding,
It can be performed by various methods such as calender molding and blow molding. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0030]

EXAMPLES The components blended in the following Examples and Comparative Examples are as follows. <Component a-1: EPDM> Ethylene-propylene-ethylidene norbornene copolymer rubber Keltan K712 manufactured by Idemitsu DSM Corporation [propylene content:
40% by weight, Mooney viscosity ML _{1 + 4} (125 ° C): 6
3, Iodine value: 16] <Component a-2: Hydrogenated SIS> Hydrogenated styrene-isoprene-styrene block copolymer Hybler 7125 manufactured by Kuraray Co., Ltd. [styrene content 20
%]

<Component b (1): HDPE> High-density polyethylene JALEX HD5050 manufactured by Japan Polyolefin Co., Ltd. [MFR (190 ° C.) = 5.0 g / 10 min] <Component b (2): PP> Polypropylene Sumitomo Chemical Industrial Co., Ltd. W501 [MFR (230 ° C.) = 3.1 g / 10 min] <Component b (3): POE> Ethylene-octene copolymer (polyolefin elastomer) Engage EG8200 manufactured by Dow Chemical Japan Co., Ltd.

<Component c (1): Silicone containing SiH> Polyorganohydrogensiloxane Nippon Unicar Co., Ltd.

[0033]

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<Component c (2): Silicone containing SiH> Polyorganohydrogensiloxane Nippon Unicar Co., Ltd.

[0035]

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<Component d (1): Platinum Catalyst MB> Platinum / Tetramethyldisiloxane Complex Polyethylene Masterbatch 5 g of a platinum / vinylsiloxane complex (platinum content 2 wt%) dissolved in polydimethylsiloxane was mixed with high-density polyethylene (specific gravity). 0.95) by melt-kneading in 95 g. (Platinum content in catalyst masterbatch: 0.
<Component d (2): supported platinum catalyst> 3% by weight of Aerosil chloroplatinic acid hexahydrate (manufactured by Yasuda Pharmaceutical Co., Ltd.) supporting chloroplatinic acid 2-
A propanol solution was prepared, and 10 g of this solution was added to colloidal silica (Aerosil 200 manufactured by Nippon Aerosil) 10
It was prepared by supporting it in 0 g. (Platinum content in the supported catalyst: 0.1 wt%) <Component d (3): rhodium complex MB> Polyethylene master batch of bis-cyclooctadiene rhodium salt 1 g of bis-cyclooctadiene rhodium salt was added to low-density polyethylene (specific gravity 0). .923) by melt-kneading in 500 g.

<Component e: Organic peroxide> Dicumyl peroxide <Other components: Paraffin oil> Diana Process Oil PW-380 manufactured by Idemitsu Kosan Co., Ltd.
[Paraffinic process oil, kinematic viscosity: 381.6c
st (40 ° C), 30.1 (100 ° C), average molecular weight 7
46]

Examples 1 to 12 Of the components described in Examples of Tables 1 and 2, all components except for components d and e were melt-kneaded at about 190 ° C. for 20 minutes using a kneader. Roll sheet. This roll sheet was cooled to room temperature, pelletized with a sheet pelletizer, and a thermoplastic resin composition to be subjected to dynamic crosslinking was obtained. Table 1 shows the pellets.
The described components d and e are added, and the mixture is kneaded using a twin-screw kneader at a shearing rate of 800 / sec so as to sufficiently plasticize according to the base resin (resin temperature 180 to 250 ° C). A thermoplastic elastomer composition was obtained. Injection molding was performed using this composition, and various physical properties were evaluated. The moldability was evaluated by extrusion molding.

<< Comparative Examples 1 to 6 >> In Comparative Example 1, the crosslinking was carried out by using only the organic peroxide (e) for the crosslinking of the rubber component. In Comparative Example 2, an organic peroxide was not used, and Example 1 was used using a silicone-based crosslinking agent and a rhodium catalyst described in US Pat. No. 4,803,244.
The same was done. In Comparative Example 3, an alkyl phenol resin [SP104 from Schenectady Chemicals] was used for crosslinking the rubber component.
5] and 5 parts by weight of a crosslinking assistant [stannic chloride] in the same manner as in Example 1. In Comparative Examples 4 and 5,
It carried out like Example 2 and 3 without using an organic peroxide. The evaluation items of each of the obtained elastomers are shown below.

Evaluation (1) Hardness (JIS K6301 A type) (2) Compression set CS [%] (JIS K6301, 2
(5% compression 70 ° C. × 22 HR) (3) Weathering and discoloration resistance test Using a sunshine weather meter, 88 ° C. × 10
(4) Formability (C using a screw of L / D = 20 using a φ50 mm extruder and a die of 100 mm × t0.5)
/R=3.0, kneading temperature 200 ° C., rotation speed 100 rpm
, A tape of 150 × 500 mm was prepared, and the surface was visually observed. × was observed when 10 or more spots having a diameter of 100 μm or more were observed, and Δ △ was observed when 2 to 9 spots were observed.
In the case where only less than three spots were observed, it was marked as “○”. As is clear from Table 1 below, the elastomer composition of the present invention can realize excellent compression set without impairing moldability and weathering resistance.

[0041]

Industrial Applicability The thermoplastic elastomer of the present invention has excellent compression set similar to vulcanized rubber and excellent weather discoloration resistance without impairing moldability, so that it has a wide degree of freedom in coloring. And various applications that require long-term reliability.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 83/05 C08L 83/05 (72) Inventor Atsushi Sugisaki 2-5-8 Higashishinagawa, Shinagawa-ku, Tokyo Sumitomo Bakelite Co., Ltd.

Claims (3)

[Claims] 1. An unsaturated double bond-containing rubber (a), an olefin resin (b), a silicone compound having two or more SiH groups in a molecule (c), a platinum hydrosilylation catalyst (d), A thermoplastic elastomer composition obtained by dynamically heat-treating a mixture containing at least an organic peroxide (e). 2. A silicone compound (c) having 10 to 150 parts by weight of an olefin resin (b) and 100% by weight of an unsaturated double bond-containing rubber (a) and two or more SiH groups in a molecule. 0.1 to 30 parts, platinum-based hydrosilylation catalyst (d) 0.0001 to 0.02 parts by weight, organic peroxide (e) 0.05 to 2 parts by weight, and paraffinic oil (f) 10 to 10 parts A thermoplastic elastomer composition obtained by dynamically heat-treating a mixture consisting of 300 parts by weight. 3. An unsaturated double bond-containing rubber (a) is an ethylene-α-olefin-nonconjugated diene copolymer (a-
1), a vinyl aromatic compound-conjugated diene copolymer and a copolymer obtained by partially hydrogenating the unsaturated double bond thereof (a-
2), a conjugated diene copolymer and a copolymer (a-3) in which the unsaturated double bond is partially hydrogenated, butyl rubber (a-
4) wherein the olefin resin (b) is polyethylene, polypropylene, ethylene-α
3. The thermoplastic elastomer according to claim 1, wherein the silicone compound (c) which is at least one selected from olefin copolymers and has two or more SiH groups in the molecule is a polyorganohydrogensiloxane. 4. Composition.