JP2001206183A - Air bag cover for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly safe air bag cover for a vehicle provided by single layer injection molding, with excellent rigid feeling and thermal deformation resistance, developable without being ruptured or dispersed at the time of inflation of an air bag. SOLUTION: This air bag cover for a vehicle is manufactured by forming a thermoplastic elastomer having the following components (A) and (B) mixed so that the total thereof becomes 100 wt.% and having such physical properties as a melt flow rate is 5 g/10 min. or more and a bending modulus of elasticity is 550 MPa or more and less than 800 MPa. Component (A) Olefinic resin: 55-80 wt.% Component (B) Copolymer rubber of ethylene and 6C α-olefin or higher: 20-45 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle airbag cover. More specifically, the present invention relates to a cover that is installed on a high-speed moving body such as an automobile and stores an airbag that protects an occupant by inflating and deploying by sensing the impact or deformation in the event of a collision or the like.

[0002]

2. Description of the Related Art An airbag system is a system for protecting a driver or a passenger in the event of a collision of an automobile or the like, and comprises a device for sensing a shock in the event of a collision and an airbag device. The airbag device comprises an airbag, an airbag actuating device, and a cover for accommodating the same. These devices include a steering wheel, an instrument panel in front of a passenger seat, a front pillar, a side pillar, a rear pillar, and a side portion of a seat. Installed in When a large impact is received due to a vehicle collision or the like, the airbag housed in the airbag case is inflated, the airbag cover is pushed open from the inside, and the airbag is deployed in the passenger compartment. I have.

[0003] The airbag cover used in such a structure is formed by urethane foam molding using a metal as a core material, or a polymer alloy of modified polyphenylene oxide and 6-nylon for the core material for the purpose of reducing the weight of the product. There is urethane foam molding using a hard plastic and inserting a reinforcing material such as a 6-nylon net. However, modified polyphenylene oxide and 6
-When a polymer alloy with nylon is used as the core material, the weight of the product can be reduced, but the deployment performance at low temperatures tends to be reduced. A process is required.

As an attempt to solve these problems, Japanese Patent Laid-Open No.
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, which are disadvantages of the two-color injection-molded cover by single-layer injection molding. Were proposed. With these proposals, it is possible to form an airbag cover in an airbag apparatus using a normal injection molding machine, and the molding cycle is shortened.

[0005]

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 side pillar.
In this case, a member having a smaller difference in rigidity and appearance from an adjacent member is required. The airbag cover formed by the two-color injection molding or the single-layer injection molding has a thin portion (tear line) for easily tearing the airbag cover when the airbag is deployed, so the rigidity is deteriorated and the heat-resistant deformation is generated. It was not satisfactory in terms of sex.

As a method for solving this problem, Japanese Patent Laid-Open No. 11-2
An airbag cover as described in 36483 is also proposed. This cover is composed of a cover main body, a mounting part for fixing the cover main body to the fixing member, and a hinge part arranged near the mounting part, and these parts are on the same plane. Although it has good rigidity, it uses a low-flow resin to increase the strength of the hinge part, so when molding a cover with a complicated structure or a long structure, the molding temperature must be increased. In addition, there is a problem that the molding cycle is long, productivity is low, and defects such as flow marks are liable to occur in the appearance of the product.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a vehicle air using a thermoplastic elastomer having specific physical properties in which specific components are blended in a specific ratio. The bag cover does not need to be reinforced by inserting a 6-nylon net or the like, and while being excellent in rigidity and heat-resistant deformation, it has high hinge strength and mounting strength, and the cover for storing the airbag is made of an instrument panel or an automobile. It can be attached to the car body itself or via parts such as metal inserts or metal inserts.It has excellent moldability and product appearance, and it has high safety that it deploys without breaking or scattering when the airbag inflates. The present invention has been completed.

That is, the gist of the present invention is to provide the following component (A):
(B) is added so as to be 100% by weight, and a melt flow rate (JIS K6758, 230
C., 21.17 N load) is 5 g / 10 min or more, and the flexural modulus (JIS K7203) is 550 MPa or more and 800 M.
A vehicle airbag cover formed by molding a thermoplastic elastomer having physical properties of less than Pa. Component (A): 55 to 80% by weight of olefin resin Component (B): 20 to 45% by weight of a copolymer rubber of ethylene and an α-olefin having 6 or more carbon atoms.

Further, the vehicle airbag cover described above, wherein the thermoplastic elastomer has a tensile breaking strength to flexural modulus ratio of 0.03 to 0.07, and the thermoplastic elastomer has an Izod impact strength of 25 KJ /. m ² or more,
A vehicle airbag cover as described above. The vehicle airbag cover described above, wherein the Izod impact strength of the thermoplastic elastomer is 30 KJ / m ² or more, and the composition of the thermoplastic elastomer is as follows: Component (A): 55 to 75% by weight of an olefin-based resin; And the component (B): 25 to 45% by weight of a copolymer rubber of ethylene and an α-olefin having 6 or more carbon atoms, wherein the airbag cover for a vehicle according to the above is one aspect of the present invention. One.

[0010] Further, the vehicle airbag cover described above, wherein the component (A) and the component (B) each satisfy the following physical properties. Component (A): melt flow rate is 10 to 100 g / 1.
0 minute, a propylene / ethylene block copolymer having an ethylene content of 10% or less and a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) of 5 to 10, Component (B): melt flow rate Which is 10 g / 10 min or less and has a density of 0.88 g / cm ³ or less, is also an embodiment of the present invention.

[0011] In addition, component (A) and component (B)
100 parts by weight of the total of a vehicle air bag cover according to the above further comprising the following components (C), the component (C): density of 0.87 g / cm ³ or less of ethylene and carbon atoms of 4 or less Copolymer with α-olefin 1
-20 parts by weight, the total of the components (A) and (B) being 10
The vehicle airbag cover according to the above, further comprising the following component (D) based on 0 part by weight, Component (D): 1 to 20 parts by weight of a styrene-based elastomer,
The vehicle airbag cover described above, wherein the styrene elastomer of the component (D) is a hydrogenated aromatic vinyl-conjugated diene block copolymer rubber, and a front pillar, a side pillar of an automobile, And the vehicle airbag cover according to the above, which is installed on one of the rear pillar and the rear pillar. And the like are also one embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION [Composition for Vehicle Airbag Cover] (1) Constituent Materials The materials constituting the thermoplastic elastomer composition for an airbag cover of the present invention include the components (A) and Each specific component of (B) is used.

Component (A): Olefin resin The olefin resin used in the present invention includes:
For example, homopolymers of α-olefins having about 2 to 8 carbon atoms such as ethylene, propylene, 1-butene, etc .;
-Olefins and ethylene, propylene, 1-butene, 3
-Methyl-1-butene, 1-pentene, 4-methyl-1
-About 2 to 20 carbon atoms such as pentene, 1-hexene, 1-octene, 1-decene and other α-olefins, vinyl acetate, acrylic acid, methacrylic acid, acrylates, methacrylates, styrene, vinyl chloride And the like with a vinyl compound such as, specifically,
For example, ethylene homopolymer such as low / medium / high density polyethylene, ethylene-propylene copolymer, ethylene-1
-Butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer Polymers, ethylene resins such as ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, propylene homopolymer, propylene-ethylene copolymer, propylene- Ethylene-1-butene-
Examples thereof include propylene-based resins such as copolymers, and 1-butene-based resins such as 1-butene homopolymer, 1-buteneethylene copolymer, and 1-butene-propylene copolymer.

As the olefin resin used in the present invention, a propylene resin is preferable, and a propylene / ethylene block copolymer is particularly preferable. In that case, the ethylene content is preferably 1 to 10%, more preferably 2 to 8%. The melt flow rate is 10 to 100 g / 10 min (JIS K675).
8, 230 ° C., 21.17 N load), preferably 15 to
Those having a weight of 80 g / 10 minutes are preferred. Further, the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 5 to 10
Is preferred.

When the ethylene content is higher than the above range, the flexural modulus and the heat deformation resistance tend to decrease. When the melt flow rate is less than 10 g / 10 min, the moldability and product appearance tend to be inferior. When the melt flow rate exceeds 100 g / 10 min, the tensile fracture strength (JIS K7113, No. 2 dumbbell) and Izod impact strength (JIS K7110, −30 ° C.) tend to decrease. When the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) is less than 5, flow marks tend to be easily generated during injection molding, and when it exceeds 10, the flexural modulus and tensile strength tend to decrease. Becomes

Component (B): Copolymer rubber of ethylene and α-olefin having 6 or more carbon atoms. Ethylene and α having 6 or more carbon atoms used in the present invention.
-As a copolymer rubber with olefin, a catalyst formed from a soluble vanadium compound and an organoaluminum compound in the presence of hydrogen and ethylene and an α-olefin having 6 to 12 carbon atoms, or a Kaminski type catalyst or the like. Those which are used and are continuously copolymerized are preferred. Examples of the α-olefin of the copolymer rubber of ethylene and an α-olefin having 6 or more carbon atoms include 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and the like. Among them, 1-hexene and 1-octene are preferred.

The copolymer rubber of ethylene and an α-olefin having 6 or more carbon atoms has a melt flow rate (JI
SK6758, 230 ° C, 21.17N load) is 10
g / 10 minutes or less, more preferably 5 g / 10 minutes or less. In addition, the density (JIS K711
2) is 0.88 g / cm ³ or less, more preferably 0.1 g / cm ³ or less.
It is preferably 875 g / cm ³ or less.

If the melt flow rate exceeds the above range, the tensile strength (JIS K7113, No. 2 dumbbell) of the blend of the component (A) and the component (B) tends to decrease, and the air bag This may cause a problem in airbag cover deployment performance during operation. When the one having a density exceeding the above range is used, the Izod impact strength (JIS K7) of the blend of component (A) and component (B) is used.
110, -30 ° C).

(2) Additional Components The following components can be added to the constituent material of the cover for storing an airbag of the present invention according to the purpose. Component (C): Copolymer of ethylene and α-olefin having 4 or less carbon atoms The compound is blended for the purpose of adjusting the low-temperature Izod impact performance and flexural modulus of the thermoplastic elastomer. As the copolymer of ethylene and the α-olefin having 4 or less carbon atoms as the component (C), a rubber of a copolymer of ethylene and an α-olefin having 4 or less carbon atoms, a rubber having ethylene and a carbon atom having 4 or less carbon atoms. Copolymers of 4 or less α-olefins and non-conjugated dienes can be exemplified.

The α-olefin of the component (C) includes propylene and 1-butene. Examples of the conjugated diene component of the copolymer of ethylene, an α-olefin having 4 or less carbon atoms and a non-conjugated diene include 5-ethylidene norbornene, 5-methylnorbornene, 5-vinylnorbornene, and dicyclopentadiene. . Specific examples include an ethylene / propylene copolymer, an ethylene / butene copolymer, and an ethylene / propylene / non-conjugated diene copolymer. The ethylene and α- having 4 or less carbon atoms
The copolymer with an olefin has a density (JIS K711).
It is preferable that 2) is 0.87 g / cm ³ or less.
If the density exceeds the above range, the effect of improving the low-temperature Izod impact performance tends to decrease.

Component (D): Styrene-based elastomer The styrene-based elastomer is blended for the purpose of adjusting the low-temperature Izod impact strength, tensile breaking strength, and scratch resistance of the product surface. Examples of the styrene-based elastomer include a copolymer of an aromatic vinyl compound and a conjugated diene compound and a copolymer of ethylene and an aromatic vinyl compound. Above all,
Hydrogenated aromatic vinyl-conjugated diene block copolymer rubber composed of at least two polymer blocks composed of an aromatic vinyl compound and at least one polymer block composed of a conjugated diene compound, at least one aromatic compound A hydrogenated product of a polymer block composed of an aromatic vinyl compound and a polymer block composed of at least one conjugated diene compound or a block copolymer rubber composed of an aromatic vinyl compound-conjugated diene compound random copolymer block, and at least one Block copolymer consisting of a polymer block composed of two aromatic vinyl compounds, an aromatic vinyl compound-conjugated diene compound random copolymer block, and an aromatic vinyl compound-conjugated diene compound tapered copolymer block in which the aromatic vinyl compound is gradually increased. Hydrogenated polymer rubber, preferably Of these at least two aromatic vinyl composed of an aromatic polymer block comprising a vinyl compound and at least one polymer block comprising a conjugated diene compound - hydrogenated product of conjugated diene block copolymer rubber are particularly preferred.

The hydrogenated aromatic vinyl-conjugated diene block copolymer preferably has a styrene block content of 20 to 40% by weight, particularly 25 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 referred to as SB-
S), styrene-isoprene block copolymer (hereinafter, referred to as
Simply SIS), styrene-butadiene-isoprene block copolymer (hereinafter simply S-BI-S), hydrogenated styrene-butadiene copolymer (hereinafter simply hydrogenated SBS) Styrene, ethylene, butadiene,
Styrene copolymer (SEBS) and the like.

(3) Other optional components In addition to the above-mentioned additional components, optional components that can be blended according to various purposes within a range that does not significantly impair the effects of the present invention include colorants, oxidants, and the like. Inhibitors, heat stabilizers, light stabilizers, ultraviolet absorbers, various inorganic fillers, various thermoplastic elastomers other than those described above, neutralizing agents, lubricants, antifogging agents, antiblocking agents, slip agents, flame retardants, dispersants, Examples of the additive include various additives such as an antistatic agent, a conductivity imparting agent, a metal deactivator, a molecular weight regulator, a bactericide, and a fluorescent whitening agent. In particular, it is desirable to add an inorganic filler, and talc is desirable because of its shape (scale shape). The used amount is about 3 to 15 parts by weight with respect to 100 parts by weight of the resin, and the talc particle size is preferably 1 to 6 μm in terms of impact performance.

(4) Blending Ratio The blending ratio of each component constituting the thermoplastic elastomer composition for an airbag storage cover of the present invention is such that the olefin resin of the component (A) is 55 to 80% by weight, preferably 55 to 80% by weight.
75% by weight, and the copolymer of ethylene of component (B) and an α-olefin having 6 or more carbon atoms has a rubber content of 20 to
The content is 45% by weight, preferably 25 to 45% by weight. When the mixing ratio of each component is out of the above range, the following problems occur.

If the compounding ratio of the component (A) is less than 55% by weight, rigidity and heat deformation resistance are inferior. If it exceeds 80% by weight, after cooling in a cooling bath at -35 ° C for 30 minutes or more, It is inferior in deployment performance when mounting work is performed within minutes and a deployment test is performed. If the blending ratio of the component (B) is less than 20% by weight, the low-temperature development performance is inferior, and if it exceeds 45% by weight, the rigidity and the heat deformation resistance are inferior.

The proportion of the additional component (C) and / or component (D) is 1 to 20 parts by weight, preferably 100 parts by weight, per 100 parts by weight of the total of components (A) and (B). It is 3 to 18 parts by weight.

If the compounding ratio of the component (C) exceeds 20 parts by weight, the rigidity and heat deformation resistance are poor, and the tensile strength at break tends to be low. If the compounding ratio of the component (D) exceeds 20 parts by weight, rigidity and heat deformation resistance are inferior, and moldability is inferior and product appearance tends to deteriorate.

(5) Production of Thermoplastic Elastomer Composition The thermoplastic elastomer composition is prepared by uniformly mixing the above components with a Henschel mixer, a ribbon blender, a V-type blender, a screw blender, or the like, and then using a conventional extruder or Banbury. Mixer, roll, brabender,
It is produced by kneading in a conventional manner using a kneader or the like, but is preferably produced using an extruder, particularly a twin-screw extruder.
At that time, the following crosslinking agent or crosslinking auxiliary agent may be blended and dynamically heat-treated to partially crosslink.
The degree of crosslinking is preferably about 10 to 40%. The degree of crosslinking is expressed by the ratio of the residue (residual residue) extracted by immersing a 100 g sample in xylene at 144 ° C. for 20 hours with respect to the original sample weight.

Crosslinking agent: As the crosslinking agent for partially crosslinking, it is preferable to use an organic peroxide.
2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexyne, 1,3-bis (t −
Butylperoxyisopropyl) benzene, 1,1-di (t-butylperoxy) -3,5,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (benzoylperoxy) -3-hexyne, Dimicle peroxide and the like can be mentioned. The amount of addition is about 0.01 to 1 part by weight.

Crosslinking aid: N, N 'is used as a crosslinking aid used for partial crosslinking with the above organic peroxide.
-Functionalities such as m-phenylene bismaleimide, toluylene bismaleimide, P-quinone dioxime, nitrobenzene, diphenylguanidine, trimethylolpropane, divinylbenzene, ethylene glycol dimethacrylate, polyethylene glycol methacrylate, trimethylolpropane trimethacrylate, allyl methacrylate, etc. Compounds and the like. The addition amount is 0.0
It is about 1 to 1 part by weight.

(6) Physical Properties of Thermoplastic Elastomer Composition The physical properties of the thermoplastic elastomer composition used as a raw material of the above-mentioned vehicle airbag cover are as specified in JIS K67.
Melt flow rate at 230 ° C. and a load of 21.17 N according to No. 58 is 5 g / 10 min or more, JIS K7203
Is 550 MPa or more and less than 800 MPa. Furthermore, the tensile fracture strength (JISK7113,
No. 2 dumbbell) and the flexural modulus of 0.03-0.0
7. The -30 ° C Izod impact strength according to JIS K7110 is 25 KJ / m ² or more, more preferably 30 KJ / m ^2.
Those having the above physical properties are preferable.

When the melt flow rate is less than the above range, the productivity is poor, and a product defect such as a flow mark or a short shot tends to occur, resulting in a poor product appearance. If the flexural modulus is less than the above range, the rigidity and heat deformation resistance are inferior. If the flexural modulus exceeds the above range, the Izod impact strength tends to decrease.

Further, when the ratio between the tensile fracture strength and the flexural modulus is less than the above range, the strength is reduced due to the concentration of stress on the hinge portion and the mounting portion due to the deformation at the time of development, so that cracks and breakage are likely to occur. Deployment performance tends to decrease. On the other hand, if it exceeds the above range, the tensile elongation at break tends to decrease, and during deployment, stress concentration on the hinge portion and the mounting portion becomes difficult to be alleviated, cracking, breakage, etc. tend to occur, and the deployment performance tends to decrease. . In addition, if the Izod impact strength is less than the above range, the tolerance of fracture energy in a portion where stress concentration is likely to occur, such as a mounting portion or a portion having a hinge structure, becomes low during a low-temperature deployment test. In this case, breakage tends to occur in the portion, and low-temperature deployability tends to decrease.

[Molding] As a method of manufacturing a vehicle airbag cover, various molding methods can be applied. Usually, an injection molding method or, if necessary, a gas injection molding method or an injection compression molding method is used. It is preferable to use a molding method such as a short shot foam molding method. As the molding conditions when using injection molding, generally, a molding temperature of 100 to 300 ° C., preferably 150 to 280 ° C., 5 to 100 MPa,
Preferably an injection pressure of 10 to 80 Mpa, 20 to 80
C., preferably at a mold temperature of 20-60.degree.

The vehicle airbag cover of the present invention may be used as a single-layer injection-molded product, but it may have a structure having a skin layer and, if necessary, a synthetic resin foam layer, or a soft PVC or olefin-based heat-resistant material. Examples include a method in which a composite sheet comprising a skin layer of a plastic elastomer and a foamed layer of a polyolefin-based resin is shaped by vacuum molding or the like, and then adhered to a vehicle airbag cover.

[Use] The vehicle airbag cover thus obtained is operated by sensing the impact or deformation of a high-speed moving body such as an automobile in the event of a collision or the like, and the vehicle is inflated and deployed. Used as an airbag storage cover for an airbag system. In particular, it is suitable for a cover that is attached to a thin frame portion such as a front pillar, a side pillar, a rear pillar, or the like, and that operates to open without opening the cover during operation.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to explain the vehicle airbag cover of the present invention in more detail, an experimental example will be specifically described below. [1] Raw materials In the examples and comparative examples, the following raw materials were used.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[2] Evaluation method Various evaluations in these examples and comparative examples were performed by the following methods. However, the measurement samples in (2) to (5) were obtained by using an in-line screw type injection molding machine (injection molding machine manufactured by Nippon Steel Works Co., Ltd .; N100B) at an injection pressure of 50 MPa, an injection temperature of 220 ° C., and a mold temperature. A piece molded at 40 ° C. was used. The measurement sample in the following (6) is an in-line screw type injection molding machine (Injection molding machine IS22 manufactured by Toshiba Machine Co., Ltd.).
0), a model product of a vehicle airbag molded at a temperature of 220 ° C. was used.

(1) Melt flow rate (g / 10 min) Temperature 230 ° C., load 2 according to JIS-K-6758
1.Measured at 17N. (2) Flexural modulus (MPa) Measured at a span of 64 mm and a bending speed of 2 mm / min according to JIS-K-7203. (3) Tensile fracture strength (MPa) According to JIS-K-7113, length 120 mm, width 8
JIS 2 punched from a 0 mm, 2 mm thick sheet
Using a No. dumbbell, the measurement was performed at a tensile speed of 50 mm / min. (4) Izod impact strength (KJ / m ² ) Measured at −30 ° C. using a notched specimen in accordance with JIS-K-7110.

(5) Heat Deformation Resistance Using a bending creep test jig in accordance with JIS-K-7116, the width direction of the test piece for bending elastic modulus evaluation (10 mm
Width) parallel to the load. Those having a deformation amount of 4 mm or less when a load of 2.2 MPa was applied in an atmosphere of 110 ° C. were regarded as having good heat deformation resistance. (6) Formability A model product of a vehicle airbag which was short shot at a molding temperature of 220 ° C. was regarded as defective. (7) Product defect The appearance of the model product of the molded vehicle airbag has sink marks.
If a flow mark was remarkably generated, it was determined to be defective.

[3] Experimental Examples Examples 1 to 16 and Comparative Examples 1 to 2 The raw materials shown in Tables 1 to 4 were used and blended in the composition shown in Tables 5 to 8 (parts by weight). 0.1 parts by weight of a phenolic antioxidant (trade name “Irganox 1010”) was added to 100 parts by weight of the total amount of the composition shown in 7, and a biaxial with L / D = 33 and a cylinder diameter of 45 mm The extruder (PCM45 made by Ikegai) was set at a temperature of 200 ° C. and melt-kneaded to obtain pellets. In Example 10, in addition to the above additives, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexane, 2,5
-Dimethyl-2,5-di (t-butylperoxy) -3
-0.1 part by weight of hexine ("Kayahexa AD" manufactured by Kayaku Akzo) and 0.2 part by weight of trimethylolpropane trimethacrylate ("acrylic ester TMP" manufactured by Mitsubishi Rayon Co.) as a crosslinking aid were added. Pellets were obtained in the same manner. The pellets were injection molded as described above and evaluated as described above. Tables 5 to 8 show these evaluation results.

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

[Table 7]

[0048]

[Table 8]

Examples 17 to 43 Tables 10 and 11 show the evaluation results obtained by blending the inorganic fillers shown in Table 9 with the compositions of Examples 1 to 16.

[0050]

[Table 9]

[0051]

[Table 10]

[0052]

According to the present invention, there is provided a vehicle airbag cover to be installed in an instrument panel, front and side pillars, etc., which does not break or scatter when the airbag is inflated, and has excellent rigidity and heat-resistant deformation. Since it can be obtained, it is useful as a cover (lid) of an airbag device that senses the collision and deformation in the event of a collision of an automobile or the like and inflates.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // (C08L 23/00 (C08L 23/00 23:08 23:08 25:04 25:04 53:02) 53: 02)

Claims (10)

[Claims] 1. The total of the following components (A) and (B) is 100
A vehicle airbag cover formed by molding a thermoplastic elastomer having physical properties of a melt flow rate of 5 g / 10 min or more and a flexural modulus of 550 MPa to less than 800 MPa. Component (A): 55 to 80% by weight of an olefin resin, Component (B): 20 to 45% by weight of a copolymer rubber of ethylene and an α-olefin having 6 or more carbon atoms 2. The thermoplastic elastomer according to claim 1, wherein the ratio between the tensile fracture strength and the flexural modulus of the thermoplastic elastomer is 0.03 to 0.07.
2. The vehicle airbag cover according to claim 1. 3. Izod impact of thermoplastic elastomer
Strength is 25KJ / m ^TwoThe above is described in claim 1 or 2.
Vehicle airbag cover. 4. Izod impact of thermoplastic elastomer
Strength is 30KJ / m ^TwoThe power according to claim 3, which is the above.
Airbag cover for goods. 5. The composition of a thermoplastic elastomer comprising: component (A): 55 to 75% by weight of an olefin resin; and component (B): a copolymer rubber of ethylene and an α-olefin having 6 or more carbon atoms. The vehicle airbag cover according to any one of claims 1 to 4, which is 25 to 45% by weight. 6. The vehicle airbag cover according to claim 1, wherein the component (A) and the component (B) satisfy the following physical properties. Component (A): melt flow rate is 10 to 100 g / 1.
0 minute, a propylene / ethylene block copolymer having an ethylene content of 10% or less and a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) of 5 to 10, Component (B): melt flow rate Is a copolymer of ethylene and an α-olefin having 6 or more carbon atoms having a density of 0.88 g / cm ³ or less. 7. A total of 10 of component (A) and component (B)
2. The composition according to claim 1, further comprising the following component (C) based on 0 parts by weight.
7. The vehicle airbag cover according to any one of claims 6 to 6. Component (C): Copolymer 1 of ethylene having a density of 0.87 g / cm ³ or less and α-olefin having 4 or less carbon atoms
~ 20 parts by weight 8. A total of 10 of component (A) and component (B)
2. The composition according to claim 1, further comprising the following component (D) based on 0 parts by weight.
8. The vehicle airbag cover according to any one of claims 7 to 7. Component (D): 1 to 20 parts by weight of a styrene elastomer 9. The vehicle airbag cover according to claim 8, wherein the styrene elastomer of the component (D) is a hydrogenated product of an aromatic vinyl-conjugated diene block copolymer rubber. 10. The vehicle according to claim 1, which is installed on one of a front pillar, a side pillar, and a rear pillar of the automobile.
10. The vehicle airbag cover according to any one of claims 9 to 9.