JPH11236483A - Housing cover for air bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a housing cover for air bag without causing breakage and scattering at the time of inflating air bag, scarcely causing trouble such as a sink mark or warpage, excellent in rigidity feeling and heat distortion resistance and useful for protecting passengers. SOLUTION: This housing cover 1 for air bag is obtained by injection molding a thermoplastic elastomer composition prepared by compounding the following components (A) and (B) so that the sum total thereof is 100 wt.% and having >=550 MPa flexural modulus of elasticity and >=30 kJ/m<2> Izod impact strength. The shape of the housing cover 1 is composed of a cover body part, a mounting part for fixing thereof to a fixed member and a hinge part 1b and the respective parts are formed on the same plane. component (A): 55-75 wt.% of a propylene- ethylene block copolymer having <=15 g/10 min melt flow rate(MFR), <=8 wt.% ethylene content and >=0.980 isotactic pentad fraction in a propylene homopolymer part and component (B): 25-45 wt.% of an ethylene-propylene- nonconjugated diene copolymer rubber having <=3 g/10 min MFR.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to storage of an airbag for protecting an occupant by operating a high-speed moving body such as an automobile by sensing the impact or deformation of the body in the event of a collision or the like and inflating and deploying it. It is about the cover.

[0002]

2. Description of the Related Art An airbag system is a system for protecting a driver or a passenger when a high-speed moving body such as an automobile collides, and comprises an apparatus for sensing an impact at the time of a collision and an airbag apparatus. The airbag device comprises an airbag, an airbag operating device, and a cover for accommodating the airbag device. These devices include a steering wheel, an instrument panel in front of a passenger seat, front and side pillars, and side portions of a seat. And so on. Then, when a large impact is received due to a vehicle collision or the like, the airbag stored in the airbag case is inflated, the airbag storage cover is pushed open from the inside, and the airbag is deployed in the vehicle interior. Has become. As a storage cover for an airbag used in such a structure, urethane foam molding using a metal as a core material, or a modified polyphenylene oxide and a 6-
There is a polyurethane foam molded by using a hard plastic such as a polymer alloy with nylon and inserting a reinforcing material such as a 6-nylon net. However, when a polymer alloy of modified polyphenylene oxide and 6-nylon is used as the core material, the product weight can be reduced, but the deployment performance at low temperatures tends to decrease, and a net-like reinforcing material is inserted. Therefore, many complicated manufacturing steps are required.

As an attempt to solve these problems, Japanese Patent Laid-Open Publication No. Hei.
JP-A-202550, JP-A-2-171362,
JP-A-2-220946, JP-A-3-18925
As described in JP-A No. 2 (1994), it comprises a skin layer using a thermoplastic elastomer having a soft feeling, and a core layer using a hard thermoplastic elastomer having shape retention. A two-color injection-molded cover in which the manufacturing process is simplified and the productivity is improved.
No. 1364, JP-A-4-151348, JP-A-4-314648, and JP-A-5-38996. A proposal has been made to reduce the cost, which is a drawback of the storage cover. According to these proposals, it is possible to mold an airbag door to be placed in an airbag apparatus using a usual injection molding machine, and the molding cycle is shortened.

[0004]

However, in the latest occupant protection airbag devices, there are cases where the airbag device is installed at an opening in the front of a passenger seat of an instrument panel, or installed at a front or a side pillar. In this case, a member having a smaller difference in rigidity and appearance between adjacent members is required. The two-color injection-molded cover and the single-layer injection-molded cover have a thin portion (tear line) for easily opening the door when the airbag is deployed, so the rigidity is poor and the heat deformation resistance is sufficiently satisfactory. I couldn't do it. Further, in the airbag storage cover having the cover main body portion, the hinge portion branched from the rear surface side, and the mounting portion for fixing to the fixing member as shown in FIG. 5, although the feeling of rigidity is good, The branch part becomes thicker than other parts, and during injection molding, the cooling rate is slower than that of the cover body, so there is a difference in the crystallinity of the material, and also when removing the product. Tend to increase in temperature. As a result, there is a problem that the difference in shrinkage ratio becomes large and defects such as sink marks and warpage are likely to occur. As a method of solving this, there is a method of reducing the thickness of the branch portion as shown in FIG. 6, but it is not preferable because the strength of the hinge portion is weakened and the airbag is easily damaged when the airbag is deployed. On the other hand, in order to secure the rigidity of the product,
When the rigidity of the material used is improved, stress concentration tends to occur at the hinge portion, and there is a problem that the hinge portion is more easily broken.

[0005]

Means for Solving the Problems The present inventor has conducted intensive studies to solve the above-mentioned problems, and as a result, has found that a thermoplastic elastomer having specific physical properties, in which specific components are blended in a specific ratio, is used. The airbag storage cover does not need to be reinforced by inserting a 6-nylon net or the like, and is excellent in rigidity and heat-resistant deformation. The airbag storage cover fixes the cover body and the cover body to the fixing member. And a hinge portion arranged near the mounting portion.These portions are formed so as to be on the same surface, so that the airbag can be deployed without breaking or scattering when inflated. It has been found that the present invention can be performed with high safety, and the present invention has been completed.

That is, the storage cover of the airbag of the present invention comprises the following components (A) and (B), and is blended so that the total thereof is 100% by weight. JIS-K7203) is 550 MPa or more, and Izod impact strength (JIS-K7110, -35)
C) is 30 KJ / m ² or more. The shape of the storage cover of the airbag formed by injection molding of the thermoplastic elastomer composition has a cover main body, an attachment portion for fixing the cover main body to a fixing member, and And a hinge portion disposed near the mounting portion, and these portions are formed on the same surface. Component (A): Melt flow rate (JIS-K6758, 230 ° C., 2.16 kg load) is 15 g / 10 min or less, ethylene content is 8 wt% or less, and isotactic pentad component of propylene homopolymer portion 55-75% by weight of propylene / ethylene block copolymer having a ratio of 0.980 or more Component (B): Melt flow rate (JIS-K6758, 230 ° C, 2.16 kg load) is 3 g / 10 min or less. Certain ethylene / propylene / non-conjugated diene copolymer rubber 25-45% by weight

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION [I] Thermoplastic Elastomer Composition for Airbag Storage Cover (1) Constituent Material The material constituting the thermoplastic elastomer composition for an airbag storage cover used for the airbag storage cover of the present invention. It is important to use the components (A) and (B) shown below. (A) Component (A): Propylene / ethylene block copolymer In the thermoplastic elastomer composition for an airbag storage cover, the propylene / ethylene block copolymer used as the component (A) includes a melt flow rate (MFR, JIS-K6758, 230 ° C, 2.16k
g load) is 15 g / 10 minutes or less, preferably 0.1 to 1
2 g / 10 min, particularly preferably 1 to 10 g / 10 min,
The ethylene content is 8% by weight or less, preferably 1 to 7% by weight, particularly preferably 2 to 6% by weight, and the isotactic pentad fraction is 0.980 or more, preferably 0.1% or more.
981 to 0.989, particularly preferably 0.985 to 0.95.
988. The isotactic pentad fraction referred to herein is an isotactic fraction in pentad units in a polypropylene molecular chain measured using ¹³ C-NMR. Further, the ethylene content is a value measured by an infrared spectrum analysis method or the like.

The production of the propylene / ethylene block copolymer is described in JP-A-56-100806 and JP-A-56-100806.
In the presence of a highly stereoregular catalyst disclosed in JP-A-120712, JP-A-58-104907, JP-A-57-63310 and JP-A-63-43915, a gas-phase fluidized-bed method is used.
It can be manufactured by applying a manufacturing process such as a solution method or a slurry method. If the melt flow rate (MFR) exceeds the above range, the Izod impact strength tends to decrease. When the ethylene content exceeds the above range, the flexural modulus and the heat deformation resistance tend to decrease. Further, those having an isotactic pentad fraction of the propylene homopolymer portion in the propylene / ethylene block copolymer of less than the above range are not suitable because of insufficient heat deformation resistance.

(B) Component (B): ethylene / propylene /
Non-conjugated diene copolymer rubber The ethylene / propylene / non-conjugated diene copolymer rubber used in the present invention includes a melt flow rate (MFR, JIS-K6758, 230 ° C, 2.16 k
g load) is 3 g / 10 minutes or less, preferably 0.1 to 2.
5 g / 10 min, particularly preferably 0.3 to 2.0 g / 10
Minutes. As an ethylene / propylene / non-conjugated diene copolymer rubber (EPDM), ethylene and propylene are combined with a non-conjugated diene such as 5-ethylidene norbornene, 5-methylnorbornene, 5-vinylnorbornene, dicyclopentadiene in the presence of hydrogen. A catalyst formed from a soluble vanadium compound and an organoaluminum compound, or, using a Kaminski type catalyst or the like, a gas-phase fluidized bed,
It can be obtained by applying a production process such as a solution method or a slurry method and copolymerizing continuously. Specific examples include ethylene-propylene-ethylidene norbornene copolymer rubber, ethylene-propylene-dicyclopentadiene copolymer rubber, and ethylene-propylene-1,4-hexadiene copolymer rubber.

The non-conjugated diene copolymer rubber is
Those having an ethylene content of 35 to 85% by weight, particularly 40 to 80% by weight, particularly 45 to 75% by weight are preferred. If the melt flow rate exceeds the above range,
The low-temperature Izod impact performance tends to decrease. Also, when the ethylene content exceeds the above range, the Izod impact performance tends to decrease,
If it is less than the above range, the tensile strength tends to decrease.

Additional Components The following components (C) to (D) can be added to the constituent material of the airbag storage cover of the present invention according to the purpose.

(C) Component (C): Ethylene homopolymer The ethylene homopolymer used in the present invention is blended for the purpose of adjusting the low-temperature Izod impact performance and the flexural modulus of the thermoplastic elastomer. Examples of the ethylene homopolymer include melt flow rates (MFR, JIS-K
6758, 230 ° C, 2.16 kg load) is 5 g / 10
Minutes or less, the density (JIS-7112) is 0.94 g / c
Those having m ³ or more are preferred. The ethylene homopolymer referred to herein is obtained by polymerizing ethylene alone in the presence of a transition metal catalyst, and there are no particular restrictions on the catalyst or polymerization method in the production of the ethylene homopolymer. Type catalysts, Phillips type catalysts and Kaminski type catalysts. Examples of the polymerization method include a slurry method and a gas phase fluidized bed method in the presence of these catalysts (for example, those described in JP-A-59-23011). Method or solution method).

(D) Component (D): Elastomer Having Block Structure of Styrene and Conjugated Diene The elastomer having a block structure of styrene and conjugated diene used in the present invention is a thermoplastic elastomer having a low-temperature Izod impact performance and a tensile breaking strength. It is blended for the purpose of adjusting the flexural modulus. As an elastomer having a block structure of styrene and a conjugated diene, a melt flow rate (MFR, JIS-K6758, 230
C., 2.16 kg load) is 20 g / 10 min or less, and the elastomer having a block structure of styrene and conjugated diene has a styrene block portion of 20 to 40% by weight, especially 2% by weight.
It is preferably from 5 to 35% by weight. Examples of the conjugated diene include those composed of butadiene, isoprene or a mixture thereof. Specifically, a styrene-butadiene block copolymer (hereinafter, simply abbreviated as “SBS”), styrene. Isoprene block copolymer (hereinafter simply abbreviated as “S-I-S”), styrene-butadiene-isoprene block copolymer (hereinafter simply abbreviated as “S-BI-S”), styrene A hydrogenated product of a butadiene copolymer (hereinafter simply referred to as “hydrogenated SB-
S ”. And styrene-ethylene-butadiene-styrene copolymer (hereinafter simply abbreviated as "SEBS").

Other Optional Components In addition to the above-mentioned additional components, optional components can be added according to various purposes within a range that does not significantly impair the effects of the present invention. Examples of the optional components include a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, various inorganic fillers, various thermoplastic elastomers other than those described above, a neutralizing agent, a nucleating agent, a lubricant, and an anti-fog. Agents, anti-blocking agents, slip agents, flame retardants, dispersants, antistatic agents, conductivity-imparting agents, metal deactivators, molecular weight regulators, antibacterial agents, fluorescent brighteners, pigments and pigment dispersants, etc. Additives can be mentioned.

(2) Compounding ratio The above components (A) and (B) constituting the thermoplastic elastomer composition for an airbag storage cover according to the present invention.
Is determined by the melt flow rate of the component (A) (JI
S-K6758, 230 ° C, 2.16 kg load) is 15
g / 10 minutes or less, an ethylene content of 8% by weight or less, and a propylene / ethylene block copolymer having an isotactic pentad fraction of 0.98 or more in a propylene homopolymer portion of 55 to 75% by weight, preferably Is from 57 to 72% by weight, particularly preferably from 60 to 70% by weight,
Melt flow rate of component (B) (JIS-K675
Ethylene-propylene-non-conjugated diene copolymer rubber having a weight of 8, 230 ° C and a load of 2.16 kg) of 3 g / 10 minutes or less is 25 to 45% by weight, preferably 27 to 43% by weight,
Particularly preferably, the content is 30 to 40% by weight and the component (A)
And (B) are blended so that the total amount becomes 100 parts by weight. If the mixing ratio of each component is out of the above range, the following problem occurs. If the proportion of the component (A) is less than the above range, the rigidity and the heat deformation resistance are inferior, while if it exceeds the above range, the developing performance at low temperature is inferior. When the proportion of the component (B) is less than the above range, the low-temperature development performance is inferior. On the other hand, when the proportion exceeds the above range, the rigidity and the heat deformation resistance are poor.

(3) Production of Thermoplastic Elastomer Composition The thermoplastic elastomer composition is obtained by mixing the above components with a conventional extruder, Banbury mixer, roll, Brabender,
It is manufactured by kneading in a conventional manner using a kneader or the like, and among them, it is preferable to manufacture using an extruder, particularly a twin-screw extruder.

(4) Physical Properties of Thermoplastic Elastomer Composition The physical properties of the thermoplastic elastomer composition in the present invention are as follows:
The flexural modulus (JIS-K7203) is 550 MPa or more, and the Izod impact strength (JIS-K7110,-
(35 ° C.) is 30 KJ / m ² or more. If the flexural modulus is less than the above range, problems such as insufficient rigidity and heat-resistant deformation occur. On the other hand, if the Izod impact strength is less than the above range, problems such as poor scattering at low temperature development occur.

[II] Structure The storage cover of the occupant protection airbag of the present invention using the above-mentioned thermoplastic elastomer composition has the following structure. The average thickness of the cover body depends on the desired product rigidity, but is generally preferably in the range of 2 to 6 mm. As shown in FIG. 1, an airbag storage cover 1 according to the present invention includes a cover body (deployed portion) 1a
And a mounting portion 1c for fixing the cover main body 1 to a fixing member 2a such as the instrument panel 2; and a hinge portion 1b disposed near the mounting portion 1c. It has a structure formed on the same surface. Therefore, as shown in FIG. 3, the cover body 1a is pushed open from the inside by the inflation of the airbag 3 when the airbag device is operated, and the airbag 3 can be deployed. Note that the “structure in which these parts are formed on the same surface” here means, as shown in FIG. 1, that the cover main body and the cover main body 1 a are fixed to the fixing member 2.
a, and a hinge portion 1b disposed in the vicinity of the mounting portion 1c may be formed as a flat surface, a curved surface, or a refracting surface. It is important that the parts have the structure formed on the upper part), and these parts are formed on a single surface which is not branched so as not to be formed as two or more surfaces as shown in FIGS. It is formed in.

The overall thickness of the storage cover 1 of the airbag is determined by the cover body 1a, the mounting portion 1c, and the hinge portion 1b.
It is preferable to make the thickness of the sheet as uniform as possible in consideration of the prevention of stress concentration, warpage, and sink marks for each of the above.
Specifically, each of the plate thickness of the cover main body portion 1a and t (about 2~6mm as described above) hinge thickness t _1, the attachment portion thickness t ₂ is t _1: 0.6t~1. 0t t _2: it is preferably in the range of 0.8T～1.2T. More preferably, the plate thickness of the cover main body 1a is t: 3 to 5 mm. For example, when t = 4 mm, t ₁ : 2.4 to 4 mm t ₂ : 3.2 to 4.8 mm If t ₁ <0.6t, the unfolded hinge portion 1b
When t ₁ > 1.0 t, the hinge tends to be hard to open due to high rigidity. If t ₂ <0.8t, the mounting portion 1c tends to be easily damaged, and t ₂ >
When it is 1.2 t, the plate thickness becomes too thick with respect to t ₁ , and sink and warpage are easily generated due to a difference in shrinkage.

[III] Molding The method of manufacturing the occupant protection airbag storage cover 1 is a normal injection molding method or, if necessary, a gas injection molding method, an injection compression molding method, a short shot foam molding. Various molding methods such as a molding method can be used. As the injection molding conditions, generally, a molding temperature of 100 to 300 ° C., preferably 150 to 280 ° C., an injection pressure of 5 to 100 MPa, preferably 10 to 80 MPa, 20 to 80 MPa ℃,
Preferably, molding is performed at a mold temperature of 20 to 60 ° C. The storage cover 1 of the occupant protection airbag is, as shown in FIG.
Although it may be used as a single-layer injection-molded product, a structure having a skin layer 7 and, if necessary, a synthetic resin foam layer 8,
And the synthetic resin foam layer 8, and the skin layer 7 and the synthetic resin foam layer 8 are provided with a cover 1 for an occupant protection airbag and an instrument panel 2 to which the cover 1 is attached.
A structure as shown in FIG.
As a molding method in this case, the cover layer 1 of the occupant protection airbag and the cover 1 are attached after forming the skin layer 7 by powder slush molding or vacuum molding of soft polyvinyl chloride or a thermoplastic elastomer. A method of injecting a synthetic resin foam material such as urethane between the instrument panel 2 or the like and the skin layer 7 or from a skin layer 7 of soft polyvinyl chloride or an olefin thermoplastic elastomer and a foam layer 8 of a polyolefin resin. After forming the resulting composite sheet by vacuum forming or the like, a method of adhering to the storage cover 1 of the occupant protection airbag and the instrument panel 2 to which the cover is attached, or the like can be used.

[IV] Applications The airbag storage cover 1 thus obtained is:
In the event of a collision or the like, a high-speed moving body such as an automobile operates by sensing the impact or deformation of the high-speed moving body, and inflates and deploys an airbag storage cover 1 of an airbag system for protecting an occupant.
Used as

[0022]

The present invention will be specifically described with reference to the following examples and comparative examples. [I] Raw Materials Raw materials used in Examples and Comparative Examples are shown in Tables 1 to 4.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[II] Evaluation Methods Various evaluations in Examples and Comparative Examples were performed by the following methods. However, the measurement samples in the following (2) to (4) were measured using an in-line screw type injection molding machine (Injection molding machine manufactured by Nippon Steel Works Co., Ltd .; N100B).
Injection pressure 50MPa, injection temperature 220 ° C, mold temperature 40
The peak molded at ° C was used. Further, the measurement sample in the following (5) was used for storing an occupant protection airbag storage cover molded at a temperature of 220 ° C. using an in-line screw type injection molding machine (Injection molding machine IS220 manufactured by Toshiba Machine Co., Ltd.). Was fixed to an instrument panel for evaluation. At this time, in Examples 1 to 5 and Comparative Examples 1 to 5, the storage cover 1 of the occupant protection airbag injection-molded into the shape shown in FIG. 1 was fixed to the instrument panel 2 as shown in FIG. In the sixth embodiment, an occupant protection airbag storage cover 1 injection-molded into the shape shown in FIG.
As shown in FIG. 6, the occupant protection airbag was fixed to the instrument panel 2 and the injection bag was injection-molded into a shape in which the mounting portion 1c was branched in a direction substantially perpendicular to the surface of the cover body as shown in FIG. The storage cover 10 was fixed to the instrument panel 2 as shown in FIG.

(1) Melt flow rate (g / 10 minutes) A temperature of 230 ° C. and a load of 2. according to JIS-K6758.
Measured at 16 kg. (2) Flexural modulus (MPa) Measured at a span of 64 mm and a bending speed of 2 mm / min according to JIS-K7203. (3) Izod impact strength (KJ / m ² ) Measured at −35 ° C. using a notched test piece according to JIS-K7110. (4) Heat Deformation Resistance A bending creep test jig based on JIS-K7116 was used to measure the bending elastic modulus evaluation test piece in the width direction (10 mm) parallel to the load. A sample having a deformation amount of 4 mm or less when a load of 2.2 MPa was applied in a 110 ° C. atmosphere was regarded as having good heat deformation resistance. (5) Deployment test The airbag device and the storage cover for the occupant protection airbag are fixed to the instrument panel, and left in a thermostatic chamber at the deployment test temperature (-40 ° C, 80 ° C) for 1 hour.
A deployment test was performed. The cover cracks and scatters, or breaks into a sharp shape and cannot be deployed normally,
The case where the attachment part was torn off, the hinge part was broken, or the deformation at the time of deployment was large, and the case where normal deployment was performed without any of the above-mentioned problems was regarded as good.

[II] Examples and Comparative Examples Examples 1 to 6 and Comparative Examples 1 to 6 The raw materials shown in Tables 1 to 4 were used and blended in the composition shown in Tables 5 to 6 (here, The amounts of component (C) and component (D) are based on a total of 100 parts by weight of component (A) and component (B), respectively.) Components (A) and (B) of the composition shown in Tables 5 and 6
Of a phenolic antioxidant (trade name "Irganox 101" manufactured by Ciba-Geigy) with respect to 100 parts by weight of
0 ") 0.1 parts by weight, L / D = 33, cylinder diameter 45 mm twin screw extruder (Ikegai PCM45)
The mixture was melt-kneaded at a temperature of 00 ° C. to obtain pellets. The pellets were injection molded as described above and evaluated as described above. Tables 5 and 6 show the results of these evaluations.

[0030]

[Table 5]

[0031]

[Table 6]

[0032]

The occupant protection airbag storage cover according to the present invention is less likely to cause sink marks, warpage and the like, does not break or scatter when the airbag is inflated, and has excellent rigidity and heat-resistant deformation. An airbag cover for protecting the occupants installed in the instrument panel, front and side pillars, etc. can be obtained. In the event of a collision with a high-speed moving object such as an automobile, the impact or deformation is sensed and the inflation is expanded. It is useful as a cover (lid) of an airbag device that performs the above.

[Brief description of the drawings]

FIG. 1 is a perspective view of a storage cover of an occupant protection airbag according to an embodiment of the present invention.

FIG. 2 is a perspective view of an instrument panel to which a storage cover of the occupant protection airbag of the present invention of FIG. 1 is attached.

FIG. 3 is a view showing A of the instrument panel of FIG. 2 with a storage cover of the occupant protection airbag of the present invention attached thereto.
FIG. 4 is a cross-sectional view taken along a line A.

FIG. 4 is a sectional structural view of an instrument panel in which a storage cover for an occupant protection airbag of the present invention is attached, and a skin layer and a synthetic resin foam layer are formed thereon.

FIG. 5 is a perspective view of a storage cover of a conventional occupant protection airbag in which a hinge portion and a mounting portion to a fixing member are branched on a back surface side of a cover main body.

FIG. 6 is a perspective view of a storage cover of the conventional occupant protection airbag of FIG. 5 in which a hinge portion is thinned.

7 is a sectional structural view of an instrument panel to which a storage cover for a conventional occupant protection airbag in which a hinge portion in FIG. 6 is thinned is attached.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Airbag storage cover (on the same surface as hinge portion) 1a Cover body portion (deployed portion) 1b Hinge portion 1c Attachment portion 1d Nail engaging portion 2 Instrument panel 2a Instrument panel attachment portion 3 Airbag 4 Inflator 5 Air Bag / module case 5a Module case fixing auxiliary member 6 Reinforcement 7 Soft polyvinyl chloride layer (skin layer) 8 Polyurethane foam layer (synthetic resin foam layer) 9 Branch part 10 Airbag storage cover (with branch hinge part) 11 Airbag storage cover (with thinner branch hinge) 12 Hinge thinner

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 23:00 B29L 31:30 (72) Inventor Yoshinori Nishiya 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Yokkaichi Business Inside

Claims (1)

[Claims] 1. A composition comprising the following components (A) and (B):
The blending is performed so that the total is 100% by weight, and the physical property value thereof is 550 M in flexural modulus (JIS-K7203).
Pa or more, Izod impact strength (JIS-K7110,
The shape of the storage cover of the airbag formed by injection molding a thermoplastic elastomer composition having a temperature of -35 ° C. or more of 30 KJ / m ² or more has a cover main body and a mounting portion for fixing the cover main body to a fixing member. And a hinge portion disposed near the mounting portion, wherein the respective portions are formed on the same surface. Component (A): Melt flow rate (JIS-K6758, 230 ° C., 2.16 kg load) is 15 g / 10 min or less, ethylene content is 8 wt% or less, and isotactic pentad component of propylene homopolymer portion 55-75% by weight of propylene / ethylene block copolymer having a ratio of 0.980 or more Component (B): Melt flow rate (JIS-K6758, 230 ° C, 2.16 kg load) is 3 g / 10 min or less. Certain ethylene / propylene / non-conjugated diene copolymer rubber 25-45% by weight