JPH0820687A - Olefinic thermoplastic elastomer composition for air bag covering material - Google Patents

Abstract

PURPOSE:To obtain the subject composition, containing a highly fluid polypropylene, polyethylene, a high-molecular weight ethylenic copolymer rubber and a mineral oil-based softener and capable of providing an air bag cover, surely broken in operation without scattering fragments. CONSTITUTION:This composition contains (A) 20-60wt.% polypropylene having 20-200g/10min melt flow rate (at 230 deg.C under 2.16kg load), (B) 5-30wt.% polyethylene (preferably a low-density polyethylene or a linear low-density polyethylene), (C) 75-10wt.% ethylenic copolymer rubber having >=50 Mooney viscosity (ML1+4, 100 deg.C) (e.g. an ethylene-propylene copolymer rubber) and (D) a mineral oil-based softener (preferably a petroleum-based softener) in an amount of 10-120 pts.wt. based on 100 pts.wt. total amount of the components (A), (B) and (C). Furthermore, the composition is preferably obtained by a method for previously kneading the components (C) with (D), preparing an oil extended composition, then blending the prepared composition with the components (A) and (B) and kneading the resultant mixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an olefinic thermoplastic elastomer composition for an air bag cover material mounted on a vehicle as a safety device. More specifically,
It is attached to the steering wheel and the instrument panel part to store the airbag that protects the driver or passenger in the passenger seat by inflating it in the event of a vehicle collision. The present invention relates to an olefin-based thermoplastic elastomer composition for an air bag cover material, which is free from damage pieces and is excellent in surface properties, vibration damping property, breaking strength, flexural modulus and low temperature physical properties suitable for mounting in a vehicle.

[0002]

2. Description of the Related Art An air bag system for protecting a driver or a passenger in a passenger seat in the event of a vehicle collision comprises a collision sensing device and an air bag device.
The latter air bag device is composed of an air bag, a device for generating gas for inflating the air bag, and a cover for housing them, and the cover is attached to a steering wheel in front of the driver or an instrument panel portion in front of the passenger seat.

When a sensing device is activated in a collision accident, gas is generated instantaneously from the gas generator, and the thin wall portion or the like provided in advance on the storage cover is destroyed by the pressure of the gas filling the inside of the air bag, and the passenger boarding. The airbag can be inflated and released over the entire surface of the person, restraining the occupant to the seat side, and preventing or reducing an injury accident due to a collision with a steering wheel or other control device, windshield, instrument panel, or the like.

The characteristics required for an air bag cover material are that it is instantaneously and reliably crushed by the gas pressure in the air bag at the time of a collision, that no fragments will injure the occupant during the crushing, It has the appearance characteristics suitable for being mounted on a vehicle, has damping properties that reduce the vibration transmitted from the vehicle body, and has low-temperature properties (strength etc.) that can withstand use in cold regions. .

Various structures and materials have been proposed for the air bag storage cover, but a reinforcing material is usually used for the purpose of preventing scattering of fragments during crushing. For example, there is one in which a reinforcing material such as a net is embedded in a portion other than a portion of a material such as polyurethane foam which is supposed to be broken to form the entire cover (Japanese Patent Laid-Open Nos. 50-127336 and 50-327336).
No. 55-110643), the manufacturing process for accurately embedding the reinforcing material in the entire cover except for the fractured part is complicated, resulting in low production efficiency and high cost.

Therefore, a two-layer type storage cover has been proposed which comprises a core layer (inner layer) capable of maintaining the strength and shape required for an air bag device, and a surface layer capable of giving a soft and soft feeling. For example, one comprising a core layer containing an olefinic rubber and a surface layer of a thermoplastic resin (Japanese Patent Application Laid-Open No. 2-22
No. 0946), which comprises a core layer of an olefin resin and a surface layer containing styrene rubber as a main component (JP-A-3-189252).
No. 4), an olefin elastomer and a core layer of an elastomer or resin having a tensile strength higher than that of the surface material thereof (JP-A-4-15145), a core layer of a thermoplastic polyurethane elastomer and a styrene or olefin thermoplastic For example, there is one having an elastomer surface layer (JP-A-5-286399).

In either case, the broken portion is thinned or a groove or slit is provided in the outer layer or in the inner layer in order to surely perform the breaking during operation. Since it is manufactured by integral molding, a reinforcing material is embedded. It has the advantages of higher production efficiency, better crushability, better appearance and feel, and easier strength adjustment. However, since it is necessary to perform two-layer molding of the core layer and the surface layer by using two or more kinds of materials, there is still a problem in productivity, and since the physical properties of both layers are different, there is a problem during or during molding. There is also a problem that deformation and cracks may occur due to use for a period of time.

Therefore, in recent years, a single-layer type cover that does not use a reinforcing material has also been proposed. For example, it is made of various thermoplastic elastomers such as polyester-based, polyolefin-based, polyurethane-based, polyamide-based, etc., and forms a thin portion along the portion of the surface portion that should be broken when the airbag is operated, and the thin portion of the surface portion The thickness of the cover is changed so that the portion close to the wall is thin and the outer peripheral portion is thick (JP-A-4-151348).
Hardness (JIS K6301) 70 or more, flexural modulus (JIS K720
3) consisting of olefin-based and / or styrene-based thermoplastic elastomer having a weight of 5000 kg / cm ² or less (JP-A-4-31
4648), and hydrogenated styrene-conjugated diene polymer (SEBS), rubber plasticizer (paraffinic oil) and olefinic resin having a fragile structure (slit, groove, thin portion, etc.) to be broken. JIS A hardness (JI) consisting of (polypropylene) and additives (such as antioxidants)
There is an injection-molded article (Japanese Patent Laid-Open No. 5-38996) of a thermoplastic elastomer having S K6301) of 60 to 85.

Among these compositions, those using a styrene thermoplastic elastomer (styrene-butadiene block copolymer hydrogenated product, SEBS) have insufficient impact strength at low temperatures. Further, SEBS easily forms a microphase-separated structure, and the styrene component tends to have a rod-shaped lamella structure. Therefore, it is considered that the orientation of the styrene lamella becomes unbalanced in the longitudinal direction and the lateral direction during the injection molding, the mechanical properties are likely to be different, and uniform fracture is unlikely to occur. Further, in the composition using this SEBS, the mechanical loss tangent (tan δ), which is an index of vibration damping property,
The dispersion peak of does not exist near room temperature, and the vibration damping property is insufficient. Further, JP-A-4-314648 discloses a cover using a non-crosslinking type ethylene propylene rubber-polypropylene-polyethylene-based olefinic thermoplastic resin composition having a density of 0.9. Not enough.

Therefore, an object of the present invention is to use an olefin for an air bag cover material, which basically uses a material of a polyolefin composition which is easy to mold, so that the cover is surely destroyed during operation and the fragments are not scattered. To provide a thermoplastic elastomer composition. Further, another object of the present invention is excellent in surface properties such as appearance, texture, vibration damping and touch (flexibility), and weather resistance that can be used in a wide range of temperature conditions from cold regions to tropical regions. And to provide an olefin-based thermoplastic elastomer composition for an air bag cover material, which has excellent breaking strength, flexural modulus and low-temperature physical properties. Furthermore, another object of the present invention is to
An object of the present invention is to provide an olefin-based thermoplastic elastomer composition having excellent moldability, capable of efficiently producing an air bag cover material, and recyclable after use.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on an olefin-based thermoplastic elastomer composition for an air bag cover material, which comprises a polyolefin and an olefin-based elastomer. The composition composed of a polymer rubber has excellent mechanical properties, particularly breaking strength, flexural modulus and low temperature physical properties, and has a small orientation during molding, which enables uniform fracture cleavage, and vibration damping properties. It was found that the dispersion peak of the mechanical loss tangent (tan δ), which is an index of, exists near room temperature and the vibration damping property is good. Furthermore, polypropylene with high fluidity and ethylene copolymer rubber with high molecular weight are used. And a thermoplastic elastomer composition in which a mineral oil-based softening agent is added and blended, By using a composition obtained by kneading an ethylene-based copolymer rubber with a mineral oil-based softening agent in advance and kneading it with polypropylene and polyethylene, it was confirmed that the aforementioned problems could be solved and the present invention was completed. It was

[0012]

That is, the present invention provides the following olefinic thermoplastic elastomer composition for an air bag cover material. 1) (a) Melt flow rate (230 ° C., 2.16 kg load) 20 to 200 g / 10 min polypropylene 20 to 6
0% by weight, (b) polyethylene 5 to 30% by weight,
(C) 75 to 10% by weight of an ethylene-based copolymer rubber having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 50 or more, and 100 parts by weight of the components (a), (b) and (c) in total. (D) An olefinic thermoplastic elastomer composition for an air bag cover material, which comprises 10 to 120 parts by weight of a mineral oil softening agent. 2) The olefin-based thermoplastic elastomer composition for an air bag cover material as described in 1 above, wherein (b) polyethylene is low-density polyethylene. 3) The olefin-based thermoplastic elastomer composition for an air bag cover material as described in 1 above, wherein the polyethylene (b) is a linear low-density polyethylene.

4) The ethylene copolymer rubber as the component (c) and the mineral oil softener as the component (d) are blended as an oil-extended composition in which both components are kneaded in advance. An olefin-based thermoplastic elastomer composition for an air bag cover material. 5) The olefinic thermoplastic elastomer composition for an air bag cover material as described in 1 to 4 above, which has a JIS A hardness (JIS K6301) of 80 or more and a flexural modulus (JIS K7203) of 500 to 2500 kg / cm ² .

[0014]

[Composition Components] The olefinic thermoplastic elastomer composition for air bag cover materials of the present invention will be described below. The olefinic thermoplastic elastomer composition for an air bag cover material of the present invention contains (a) polypropylene, (b) polyethylene, (c) ethylene copolymer rubber, and (d) mineral oil softener. .

The polypropylene as the component (a) is an isotactic polypropylene or a random or block copolymer of polypropylene and an α-olefin such as ethylene, butene-1, hexene-1, and the polypropylene constitutes a crystal part. To do. Melt flow rate (MFR) (230 ℃, 2.16kg load) is 20g / 1
It is 0 minutes or more, and preferably 20 to 200 g / 10 minutes. If the MFR of less than 20 g / 10 minutes is used, the moldability is deteriorated.

The polyethylene as the component (b) is a polymer of ethylene and has a melt flow rate (230 ° C., 2.16 kg load) of 0.05 g / 10 minutes or more and a density of 0.91 to 0.97 g / cm ³ and has a high density. Any of polyethylene, low density polyethylene, linear low density polyethylene and the like can be used. By adding polyethylene, breaking strength and flexural modulus are improved. Among these polyethylenes, low density polyethylene and linear low density polyethylene are particularly preferable.

The ethylene-based copolymer rubber as the component (c) used in the present invention is an amorphous random elastic copolymer containing ethylene as a main component. For example, ethylene-propylene copolymer rubber (EPR). ), Ethylene-1-butene copolymer rubber (EBR), and ethylene-propylene-non-conjugated diene copolymer rubber (EPDM).

Here, the non-conjugated diene monomer of EPDM is a non-conjugated diene having 5 to 20 carbon atoms, for example, 1,4
-Pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene and 1,4-octadiene, and, for example, 1,4-cyclohexadiene, cyclooctadiene, dicyclopentadiene, etc. A cyclic diene such as 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-methallyl-5-norbornene and 2-isopropenyl-
Examples thereof include alkenyl norbornene such as 5-norbornene. Among the above rubbers, EPR, EBR and EP
DM is preferred, and EPDM using ethylidene norbornene as the non-conjugated diene is particularly preferred from the viewpoint of providing a composition having excellent heat resistance, tensile properties and impact resilience.

The proportion of comonomer composing EPDM is
Ethylene content is 50-80% by weight, preferably 55-
70% by weight, propylene content is 20 to 50% by weight, preferably 25 to 40% by weight, diene compound content is 1 to
It is 20% by weight, preferably 2 to 10% by weight. The iodine value is preferably 3 to 70. Also, the Mooney viscosity (ML
_{1 + 4} , 100 ° C.) is 50 or more, preferably 100 or more. A low molecular weight EPDM having a Mooney viscosity of less than 50 is not preferable because the embracing property of oil (mineral oil-based softening agent) is deteriorated.

The mineral oil-based softening agent as the component (d) weakens the intermolecular action force of the rubber during roll processing of the rubber, facilitates the processing, assists dispersion of carbon black, white carbon, etc. Improves flowability and flexibility of plastic elastomers. As a specific example, paraffinic,
Examples include naphthene-based and aromatic petroleum-based softening agents, polymerized high-boiling strong aromatic oils, liquid paraffin, and white oil. Among these, petroleum-based softeners are preferable. By blending the component (d), not only the moldability is improved, but also the texture, feel, flexibility and low-temperature physical properties of the air bag storage cover are improved.

It is preferable to add a fatty acid type lubricant (e) to these components in order to improve the releasability during processing and molding. Specific examples of the fatty acid-based lubricant include stearic acid amide, erucic acid amide, oleic acid amide, methylene bis stearamide, ethylene bis stearamide, and mixtures or inclusions thereof. It can be selected depending on the conditions. Among these, erucic acid amide is particularly preferable.

In the present invention, in addition to the above components, other components can be blended if desired. For example, by adding carbon black, good weatherability can be obtained at the same time as coloring. Further, by adding a filler such as calcium carbonate, talc, kaolin, mica, glass fiber or synthetic fiber, it is possible to improve dimensional stability during molding, releasability and the like. Furthermore, ultraviolet absorbers, processing aids, heat stabilizers, light stabilizers, flame retardants, antistatic agents, nucleating agents, and the like, which are used in the field of molding resin compositions, are appropriately added in the usual proportions. can do.

[0023]

[Blending ratio of each component] The mixing ratio of each component is (a)
The proportion of polypropylene, (b) polyethylene, and (c) ethylene-based copolymer rubber is such that the component (a) is 20 to 60% by weight, preferably 30 to 50% by weight, and the component (b) is 5 to 5.
30% by weight, preferably 5 to 25% by weight of component (c)
Is 75 to 10% by weight, preferably 65 to 25% by weight. The amount of the mineral oil-based softening agent (d) is 10 to 100 parts by weight of the total of the components (a), (b) and (c).
It is 120 parts by weight.

When the content of the component (a) is less than 20% by weight, the thermoplastic elastomer obtained has a low fluidity, so that the moldability is deteriorated, and when it exceeds 60% by weight, the mechanical strength becomes too high and the cover is expected to break. Since it is necessary to reduce the thickness of the part, the molding process becomes difficult, and the appearance becomes plastic-like due to the occurrence of luster, and the touch feel deteriorates. When the content of the component (b) is less than 5% by weight, the effect of improving the physical properties does not appear and 3
If it exceeds 0% by weight, mechanical properties such as flexural modulus will increase, and it will be difficult to break the cover when the air bag is inflated when the air bag is expanded. If the content of the component (c) is less than 10% by weight, the mechanical strength will be too high and the physical properties such as impact strength at low temperature will be deteriorated, and if it exceeds 75% by weight, the fluidity will be low and the moldability will be deteriorated.

The amount of component (d) (mineral oil-based softening agent) is 1
If it is less than 0 parts by weight, the effect of the compounding will not be exhibited, and if it exceeds 120 parts by weight, the molded product is deformed, bleeding out occurs after molding, and the weather resistance is deteriorated, which is not preferable.

The component (e) (fatty acid-based lubricant) is 0.2 to 2.0 parts by weight with respect to 100 parts by weight of the components (a), (b) and (c) in total, and the compounding amount is If it is less than 0.2 parts by weight, the effect of the compounding will not be exhibited, and if it exceeds 2.0 parts by weight, bleed-out will occur and the releasability will be deteriorated.

[0027]

[Production Method of Composition] The olefinic thermoplastic elastomer composition for air bag cover material of the present invention is produced by blending and kneading the respective components in the above proportions and other additives as appropriate. However, by devising the operation procedure of compounding and kneading, the production process can be simplified and a composition having more preferable physical properties can be obtained. That is, the kneading can be usually carried out by blending all at once, but in the present invention, (c) the ethylene copolymer rubber and (d) the mineral oil-based softening agent are previously kneaded to form an oil-extended composition. It is preferable to prepare, blend this oil-extended composition with (a) polypropylene and (b) polyethylene, and knead.

When the ethylene copolymer rubber and the mineral oil-based softening agent are blended as separate components, equipment such as a tank for storing the mineral oil-based softening agent, a pump, and a preheating device are required. When using, it is possible to shorten the kneading time of the composition and (about 2 / when compared as a separate component)
Can be kneaded in 3 hours. ), The dispersibility of the ethylene-based copolymer rubber and the mineral oil-based softening agent can be enhanced, and not only the physical properties are improved, but also the productivity and the cost can be reduced. Specifically, for example, after kneading the ethylene copolymer rubber and the mineral oil softener with a kneader, or E in advance.
Oil-extended E containing PDM and mineral oil-based softener in a prescribed ratio
After the PDM is prepared, components such as polypropylene can be produced by a method using a twin-screw extruder and a hot cutter, or by kneading with a kneader or a Banbury mixer and then using a feeder ruder, a single-screw extruder and a hot cutter.

The olefinic thermoplastic elastomer composition of the present invention used as an air bag cover material is
Those having a JIS A hardness (JIS K6301) of 80 or more and a flexural modulus (JIS K7203) of 500 to 2500 kg / cm ² are particularly preferable. If the hardness is low, deformation is likely to occur and the shape retention is poor, and if the flexural modulus is high, it is difficult to break the cover when the airbag is inflated.

The method for molding the olefinic thermoplastic elastomer composition for an air bag cover material of the present invention into a cover for accommodating an air bag may be a commonly used method, for example, a breakage portion when the air bag is operated. The thin portion is molded by a general molding method such as injection molding using a mold whose inner surface becomes a recess having an H shape, for example.

[0031]

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following description. In addition, in each of Examples and Comparative Examples, the following materials were used as the resin raw material and the additive.

(A) Polypropylene (PP): MFR
(230 ℃, 2.16 load) 80g / 10min. (B) Polyethylene (PE): (1) High density polyethylene (HDPE): MFR (230
℃, 2.16 load) 30g / 10min, density 0.955g / c
m ³ , (2) Low density polyethylene (LDPE): MFR (230
℃, 2.16 load) 65g / 10min, density 0.915g / c
m ³ , (3) Linear low density polyethylene (LLDPE): MFR
(230 ℃, 2.16 load) 50g / 10min, density 0.926g
/ Cm ³ . (C) Ethylene-propylene-non-conjugated diene copolymer (EPDM): propylene content 28% by weight, iodine value 1
5, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 320. (D) Mineral oil softener (oil): paraffinic mineral oil (P
W-380, manufactured by Idemitsu Co., Ltd. (E) Fatty acid-based lubricant (lubricant): Fatty acid amide-based lubricant (Sractol WB-16, manufactured by Schill and Seilacher). (F) Styrene-butadiene block copolymer hydrogenated product (SEBS): styrene content 30% by weight, MFR (2
30 ° C, 2.16 load) 10g / 10 minutes.

Example 1 (c) EPDM and (d) oil in the proportions shown in Table 1 were kneaded in advance with a kneader at a melting temperature of 200 ° C. for 20 minutes to obtain an oil-extended EPDM, and other components were added. The components were added, and the mixture was melt-kneaded at a resin temperature of 220 ° C. with a twin-screw extruder and cut with a hot cutter to obtain an olefinic thermoplastic elastomer composition. This composition is molded to prepare a sample for measuring physical properties, and physical properties (MFR, JIS A hardness, breaking strength, tear strength, Izod impact strength, flexural modulus, vibration damping property, which serve as an index of an air bag cover material, Moldability) was measured. Table 1 shows the measurement results together with the blending ratio of each component.

Examples 2 to 4 and Comparative Examples 1 to 3 Using the components in the proportions shown in Table 1, the same procedure as in Example 1 was carried out to obtain an olefinic thermoplastic elastomer composition for an air bag cover material. It was A sample for measuring physical properties was prepared from this composition, and each physical property was measured. Table 1 shows the measurement results together with the blending ratio of each component.

[0035]

[Table 1]

The measurement and evaluation methods of each physical property shown in Table 1 are as follows. (1) MFR (g / 10 minutes): Measured at 230 ° C and 2.16 kg load. (2) JIS A hardness: Measured according to JIS K6301. (3) Breaking strength (kg / cm ² ): Measured according to JIS K6301. (4) Tear strength (kg / cm): Measured according to JIS K6301. (5) Izod impact strength (kg · cm / cm ² ): JIS
It was measured (−50 ° C.) with K7110 (with notch) and observed for breakage. NB: not destroyed, x: destroyed. (6) Flexural modulus (kg / cm ² ): Measured according to JIS K7203.

(7) Moldability: The moldability was evaluated according to the following criteria by the viscosity measured at a high-speed shearing at 220 ° C. (measured by a capillary rheometer (manufactured by Toyo Seiki Seisaku-sho, Ltd. at a shearing rate of 1000 / sec)). ⊚: 900 poise or less, ◯: 900 poise to 1200 poise or less, Δ: 1200 poise to 1500 poise or less, ×: 1500 poise or more.

(8) Damping property: With a solid viscoelasticity measuring device,
1 Hertz (H) every 5 ° C in the range of -150 ° C to 200 ° C
The constant frequency of z) was applied to the composition, the storage elastic modulus and the loss elastic modulus at each temperature were measured, and the dispersion loss obtained by the mechanical loss tangent (tan δ) and the temperature was calculated according to the following criteria. . ◯: A dispersion curve of tan δ is in the temperature range of −5 to 30 ° C., ×: Dispersion curve of tan δ is outside the temperature range of −5 to 30 ° C.

As is clear from Table 1, the polyethylenes added (Examples 1 to 4) have improved breaking strength.
Low temperature physical properties (Izod impact strength: -50 ° C) and flexural modulus also show good values, especially polyethylene is LDP.
By using E (Example 3) and LLDPE (Example 4), the tear strength is low and the breaking strength is further improved.
Polyethylene not added (Comparative Example 1), one exceeding the range of the present invention (Comparative Example 3) and SEB as a rubber component
It can be seen that, as compared with the one using S (Comparative Example 2), it shows well-balanced and good physical properties.

[0040]

The olefinic thermoplastic elastomer composition for air bag cover material of the present invention has a melt flow rate (230 ° C., 2.16 kg load) of 20 to 200 g / 10.
A composition obtained by mixing and kneading a high-fluidity polypropylene, polyethylene, a high-molecular-weight ethylene copolymer having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 50 or more, and a mineral oil-based softening agent. The composition for an air bag cover material of the present invention uses only an olefinic thermoplastic resin composition, and the air bag cover created by this is reliably destroyed during operation, and an auxiliary material such as a net is used. Even if it is not used, fragments will not scatter, operate reliably in a wide temperature range, maintain flexibility, excellent surface property and moldability,
No brittleness is observed even at a low temperature of 50 ° C, and the temperature adaptability is excellent. Further, in addition to being superior in vibration damping in a temperature range (10 to 25 ° C.) in which the frequency of use is high, the olefin resin composition is used as compared with a conventional styrene thermoplastic elastomer (SEBS etc.). Therefore, it can be efficiently produced and can be recycled after use.

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Claims (5)

[Claims] 1. A melt flow rate (230 ° C.,
2.16 kg load) 20 to 200 g / 10 min polypropylene 20 to 60% by weight, (b) polyethylene 5 to 30% by weight, (c) Mooney viscosity (ML _{1 + 4} , 100 ° C.) 50
75 to 10% by weight of the above ethylene-based copolymer rubber and 10 to 120 parts by weight of (d) a mineral oil-based softening agent based on 100 parts by weight of the components (a), (b) and (c) in total. An olefinic thermoplastic elastomer composition for an air bag cover material. 2. The olefinic thermoplastic elastomer composition for an air bag cover material according to claim 1, wherein the polyethylene (b) is low density polyethylene. 3. The olefinic thermoplastic elastomer composition for an air bag cover material according to claim 1, wherein the polyethylene (b) is a linear low density polyethylene. 4. The ethylene-based copolymer rubber as the component (c) and the mineral oil-based softener as the component (d) are blended as an oil-extended composition in which both components are kneaded in advance. An olefinic thermoplastic elastomer composition for an air bag cover material according to the above item. 5. A JIS A hardness (JIS K6301) of 80 or more and a flexural modulus (JIS K7203) of 500 to 2500 kg /
The olefin-based thermoplastic elastomer composition for an air bag cover material according to any one of claims 1 to 4, which has a cm ² size.