JPH08217927A - Thermoplastic olefin elastomer composition for air bag cover material - Google Patents

Abstract

PURPOSE: To obtain a thermoplastic olefin elastomer compsn. for an air bag cover material which is scratch-resistant, has surface characteristics suitable for the installation in a car, and gives an air bag surely broken when operated without scattering fragments by compounding a specific thermoplastic olefin elastomer component with a leather powder, a wood flour, etc. CONSTITUTION: This compsn. is prepd. by compounding 100 pts.wt. thermoplastic olefin elastomer component comprising 30-40wt.% polypropylene resin (e.g. one comprising 10-50wt.% homopolypropylene and 90-50wt.% propylene-ethylene random copolymer), 10-20wt.% low-density polyethylene, 10-40wt.% ethylene- propylene-nonconjugated diene terpolymer, and 10-30wt.% ethylene-propylene copolymer rubber with 10-50 pts.wt. component selected from among a leather powder, a wood flour, and org. fibers. The compsn. has a high scratch resistance and a good feel to the touch, gives an air bag surely broken when operated without scattering fragments, and is flexible in a wide temp. range, enabling the sure operation of the air bag.

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 protect the driver or passengers in the passenger seat in a moment of collision in the event of a vehicle collision. It has excellent vibration-damping properties suitable for mounting in the car, excellent elongation at break at high temperature, and sufficient breaking resistance even without painting the surface, and surface characteristics (appearance and touch) suitable for mounting in the car. Etc.) having an olefinic thermoplastic elastomer composition.

[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 the air bag storage cover are that the gas pressure in the air bag at the time of collision will surely crush the air bag, that no fragments will cause damage to the occupant during the crush, It has an appearance characteristic suitable for being mounted on a vehicle, a damping characteristic for reducing the vibration transmitted from the vehicle body, and the like.

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 an area other than a portion of a material such as foamed polyurethane that is supposed to be broken, to form the entire cover (Japanese Patent Laid-Open Nos. 50-127336 and 5-56).
(No. 5-110643), 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), which comprises an olefin elastomer and a core layer of an elastomer or resin having a tensile strength higher than that of the surface layer material thereof (Japanese Patent Laid-Open No. 4-15145), a core layer of a polyurethane thermoplastic 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 K7201
3) consisting of an olefin-based and / or styrene-based thermoplastic elastomer of 5000 kg / cm ² or less (Japanese Patent Laid-Open No. 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 (JIS) consisting of (polypropylene) and additives (such as antioxidants)
For example, there is a thermoplastic elastomer injection molding (K6301) of 60 to 85 (JP-A-5-38996).

On the other hand, the airbag cover is provided at a relatively easily noticeable position such as the center of the steering wheel on the driver side of the vehicle and the dashboard upper surface on the passenger side. Therefore, in order to improve the surface strength and light resistance, the conventional coating is performed in consideration of the balance with other interior skin materials. The use of unpainted interior materials is increasing, and not only can the air bag cover be used without painting, it will not only improve physical properties such as appearance characteristics and scratch resistance, but it will also be used inside vehicles. It is required to develop a material that has a good tactile sensation when worn.

Therefore, an object of the present invention is to use a material basically composed of a single polyolefin composition which is easy to mold, so that the cover is surely destroyed during operation and fragments are not scattered. An object is to provide an olefin-based thermoplastic elastomer composition for wood. Another object of the present invention is to have sufficient surface strength without coating,
An object of the present invention is to provide an olefin-based thermoplastic elastomer composition for an air bag cover material, which is excellent in appearance characteristics such as color tone and texture, particularly in touch.

Another object of the present invention is that it has excellent vibration damping properties, has weather resistance that can be used in a wide range of temperature conditions from cold regions to tropical regions, improves elongation at break, and It is intended to provide an olefin-based thermoplastic elastomer composition for an air bag cover material, which is excellent in breaking strength. further,
Another object of the present invention is to provide an olefinic thermoplastic elastomer composition for an air bag cover material, which has excellent moldability, can efficiently produce an air bag material, and can be recycled after use.

[0012]

The present inventors have found that the surface strength (scratch resistance), color tone, and
In order to improve the appearance characteristics such as feeling, especially the touch, the inventors have made earnest studies on a polyolefin-based thermoplastic composition suitable for an air bag cover material. As a result, polypropylene resin, low-density polyethylene, ethylene-propylene-non-conjugated diene copolymer rubber, olefin-based thermoplastic elastomer composition component consisting of ethylene-propylene copolymer rubber, leather powder, wood The present invention has been completed by confirming that the above-mentioned problems can be solved by a composition in which ingredients such as powder and organic fiber for improving the texture are combined.

That is, the present invention provides the following olefinic thermoplastic elastomer composition for an air bag cover material. (1) (a) Polypropylene resin 30 to 40% by weight
And (b) 10 to 20% by weight of low-density polyethylene,
100 parts by weight of olefinic thermoplastic elastomer composition component containing (c) 10 to 40% by weight of ethylene-propylene-non-conjugated diene copolymer rubber and (d) 10 to 30% by weight of ethylene-propylene copolymer rubber 10 to 50 parts by weight of (e) at least one component selected from leather powder, wood powder, and organic fiber is blended with 10 parts by weight of the olefinic thermoplastic elastomer composition for an air bag cover material. (2) The olefin for an air bag cover material as described in 1 above, wherein the polypropylene resin (a) comprises (a1) 10 to 50% by weight of homopolypropylene and (a2) 50 to 90% by weight of propylene-ethylene random copolymer. -Based thermoplastic elastomer composition.

(3) The homopolypropylene of the component (a1) has a melt flow rate (230 ° C., 2.16 kg load) of 50.
~ 150 g / 10 minutes, the propylene ethylene random copolymer of the component (a2) has a melt flow rate (23
0 ℃, 2.16kg load) 20-120g / 10 minutes,
The low density polyethylene as the component (b) has a melt flow rate (230 ° C., 2.16 kg load) of 20 to 100 g / 10 minutes, and the ethylene-propylene-non-conjugated diene copolymer rubber as the component (c) has a Mooney viscosity (ML). _{1 + 4} , 100 ℃) 3
0 to 150, and the ethylene-propylene copolymer rubber as the component (d) has a melt flow rate (230 ° C., 2.16 kg).
(Load) 5 to 30 g / 10 minutes, The olefinic thermoplastic elastomer composition for an air bag cover material according to 2 above. Hereinafter, the olefin-based thermoplastic elastomer composition for an air bag cover material of the present invention will be described.

[0015]

[Components of Composition] Specific components will be described below. (A) Polypropylene-based resin The polypropylene-based resin of the component (a) used in the present invention is a polymer of propylene, and a homopolymer of propylene as well as a copolymer with ethylene can be used.
Among these, a mixture of homopolypropylene (a1) and propylene-ethylene random copolymer (a2) is preferable.

(A1) Homopolypropylene The homopolypropylene of the component (a1) is a homopolymer of polypropylene. Those having high crystallinity are preferable, and specifically those having a boiling n-heptane insoluble component of 90% by weight or more are preferable. Homopolypropylene melt flow rate (MFR, 230 ° C, 2.16kg load) is 50-150
g / 10 minutes is preferable, and 60-100 g / 10 minutes is more preferable. If the MFR is less than 50 g / 10 minutes, the fluidity is low, so the moldability is poor, it is difficult to form a skin layer in the resin, the scratch resistance becomes insufficient, and 150 g / 10
If it exceeds minutes, the impact resistance at room temperature is poor.

(A2) Propylene-ethylene random copolymer (a2) The propylene-ethylene random copolymer of component (a2) means crystalline propylene obtained by randomly copolymerizing propylene and ethylene in the presence of a stereoregular polymerization catalyst. -Ethylene copolymer having an ethylene content of 2.0 to 4.5% by weight, preferably 2.5 to 3.5% by weight, and a melt flow rate (MFR) (230 ° C, 2.16 kg load) of 20 to 120 g.
/ 10 minutes, preferably 25 to 70 g / 10 minutes. If the MFR is less than 20 g / 10 minutes, the flowability is low and moldability is poor, and if it exceeds 120 g / 10 minutes, the impact resistance at room temperature is poor.

(B) Low Density Polyethylene The low density polyethylene of the component (b) has a density of 0.910-0.
It is a polymer of ethylene of 945 g / cm ³ and has MFR (230
C., 2.16 kg load) is 20 to 100 g / 10 minutes, preferably 25 to 80 g / 10 minutes. MFR is 50g
If it is less than / 10 minutes, the fluidity is low and the moldability is poor.
If it exceeds 100 g / 10 minutes, the impact resistance at room temperature is poor.
Linear low density polyethylene (LLDPE) can also be used as the low density polyethylene.

(C) Ethylene-propylene-non-conjugated die
Copolymer rubber ethylene-propylene-non-conjugated diene copolymer rubber (E
PDM) is an amorphous random elastic copolymer containing ethylene and propylene as main components and a non-conjugated diene component. 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 cyclic dienes such as 1,4-cyclohexadiene, cyclooctadiene and dicyclopentadiene, for example, 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-methallyl -5-norbornene and 2-isopropenyl-5-
Examples thereof include alkenyl norbornene such as norbornene. Among the above rubbers, EPDM using dichloropentadiene as the non-conjugated diene is preferable from the viewpoint of providing a composition excellent in heat resistance, tensile properties and impact resilience.

The proportion of comonomer composing EPDM is
Ethylene content is 50-80% by weight, preferably 65-
75% 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 30 to 150, preferably 70 to
120. With a low molecular weight EPDM having a Mooney viscosity of less than 30, sufficient breaking strength at high temperature cannot be obtained.
Further, when it exceeds 150, the moldability is deteriorated.

(D) Ethylene-Propylene Copolymer Rubber The ethylene-propylene copolymer rubber (EPR) used in the present invention is an amorphous random elastic copolymer of ethylene as a main component and propylene, Those having a number average molecular weight (Mn) of 20,000 or more are preferable. MFR (23
It is 10 to 30 g / 10 min, preferably 15 to 25 g / 10 min at 0 ° C. and 2.16 kg load). MFR is 10
If it is less than g / 10 minutes, the fluidity is low and moldability is poor, and if it exceeds 30 g / 10 minutes, the releasability is lowered and the low temperature properties are also lowered. The EPR preferably has an ethylene content of 50 to 90% by weight and a propylene content of 10 to 50% by weight, and further has an ethylene content of 70 to 80% by weight and a propylene content of 20 to 30%. It is more preferably the one by weight. In the present invention, by using two or more kinds of rubber, it is possible to maintain the mechanical strength and good elastic modulus at high temperature, and improve the appearance and scratch resistance.

(E) Touch Improving Component In the present invention, a material selected from leather powder, wood flour and organic fibers is added to the resin component of the olefinic thermoplastic elastomer composition as a component for improving the touch feeling. As the leather powder, powder of natural leather or synthetic leather can be used. The size of the powder is 10-150μ in diameter
m, preferably 20 to 80 μm. By blending the leather powder, it is possible to obtain the texture and feel similar to the raw leather component.

The wood powder has a size of 10 to 150 μm, preferably 20 to 80, as in the case of leather powder.
The one with μm can be used. As the organic fiber, both natural cellulose fiber and chemical fiber can be used.

As the natural cellulose fiber, wood fiber,
Seed hair fibers, bast fibers, vein fibers and the like can be mentioned. As the wood fiber, fibers (wood pulp) obtained from wood such as conifers and hardwoods and classified into mechanical pulp, semi-chemical pulp, chemical pulp and the like depending on the production method can be used. Those which are treated with a surface treatment agent (such as a silane coupling agent) and reinforced can also be used. The fiber length is preferably 1 to 20 mm, more preferably 2 to 10 mm, and the fiber width is preferably 10 to 50 μm. For example, in softwood kraft pulp, the fiber length is 3 m.
Those having a fiber width of around m and a fiber width of around 40 μm are preferably used. The shorter the fiber length, the easier it is to blend with the resin component.

The seed hair fibers include cotton (liton, fuzz, linter, etc.), the bast fibers include flax, hemp, jute, ramie, kozo, etc., and the vein fibers include Manila hemp, sisal hemp, etc. Can also be used. Examples of the chemical fiber include polyester fiber such as polyethylene terephthalate fiber and polyamide fiber such as nylon, and any of them can be used.

The fiber length of the organic fiber is 2 to 15 mm,
Furthermore, 5-10 mm is preferable. For example, a cotton linter having a fiber length of about 10 mm and a fiber width of about 20 μm is preferably used. Similar to the wood fibers, the shorter the fiber length, the better the blending with the resin component. The above-mentioned tactile-feel improving components are usually used alone, but two or more types can be used in combination.

(F) Other Components In the present invention, other components can be blended in addition to the above components, if desired. For example, by adding carbon black, good weatherability can be obtained at the same time as coloring. Also, calcium carbonate, talc, kaolin,
By adding a filler such as mica or glass 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.

[0028]

[Blending ratio of each component] The mixing ratio of each component is (a) polypropylene resin 30 to 40% by weight, (b) low density polyethylene 10 to 20% by weight, and (c) ethylene-propylene-non-conjugated diene. The copolymer rubber is 10 to 40% by weight, and the (d) ethylene-propylene copolymer rubber is 10 to 10% by weight.
It is 30% by weight. The polypropylene resin as the component (a) includes 10 to 50% by weight of (a1) homopolypropylene and (a2) 50 to 50 ethylene-propylene random copolymer.
Those containing 90% by weight are preferred.

If the amount of the component (a) is less than 30% by weight, the thermoplastic elastomer obtained will not have high temperature strength, and the moldability,
The surface property also deteriorates, and if it exceeds 40% by weight, low temperature impact resistance,
Elongation decreases. If the content of the component (b) is less than 10% by weight, the effect of improving the physical properties does not appear, and if it exceeds 20% by weight, the releasability is lowered and the high temperature strength is also lowered. When the content of the component (c) is less than 10% by weight, high temperature strength cannot be obtained, the elongation becomes insufficient and the elastic modulus becomes high, which is not preferable, and when it exceeds 40% by weight, the moldability is deteriorated. When the content of the component (d) is less than 10% by weight, the mechanical strength and the appearance are not sufficiently improved, and when it exceeds 30% by weight, the releasability and low temperature impact resistance are deteriorated and the mechanical strength at high temperature is also decreased. . As the rubber component, the total amount of the components (c) and (d) is most preferably 40 to 50% by weight.

The blending amount of the tactile feel improving component of the component (e) varies depending on the type of the component and the purpose of installing the cover material, etc., but generally, the olefinic thermoplastic elastomer composition of the above components (a) to (d). 10 to 50 parts by weight, preferably 20 to 40 parts by weight, based on 100 parts by weight of the total amount of If the amount of the component (e) is less than 10 parts by weight, the effect of the addition is not recognized, and if it exceeds 50 parts by weight, not only the properties suitable for the air bag cover material (breaking strength, etc.) are impaired, but also the tactile feeling improving component is removed from the surface. It will fall off, which is not preferable. .

[0031]

[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. be able to. Specifically, a method using a twin-screw extruder and a strand cutter,
Or after kneading with a kneader or Banbury mixer,
It can be produced by a method using a feeder ruder, a single screw extruder, a hot cutter, or the like.

The olefinic thermoplastic elastomer composition of the present invention used as an air bag cover material is
Breaking elongation at 85 ℃ (JIS K6301, 500mm / min) is 4
50% or more, breaking strength at 85 ℃ (JIS K6301) is 40k
It is preferably g / cm ² or more, the hardness is 80 or more as JIS A hardness (JIS K6301), and the bending elastic modulus (JIS K720
It is particularly preferable that 3) is 500 to 4500 kg / cm ² .

As a 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, a commonly used method may be used. 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.

[0034]

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: (a1) Homopolypropylene (HPP): MFR (230 ° C., 2.16 kg load) 80 g / 10 minutes. (A2) Propylene-ethylene random copolymer (RPP): MFR (230 ° C., 2.16 kg
Load) 30 g / 10 minutes, ethylene content 3.1% by weight. (B) Low-density polyethylene: (b1) Low-density polyethylene (LDPE): MFR (230 ° C, 2.16 kg load) 65
g / 10 minutes, density 0.915 g / cm ³ . (B2) Linear low density polyethylene (LLDPE): MFR (230 ° C, 2.16kg)
Load) 50 g / 10 minutes, density 0.926 g / cm ³ . (C) Ethylene-propylene-non-conjugated diene copolymer (EPDM): propylene content 28% by weight, iodine value 1
5, MFR (230 ℃, 2.16kg load) 0.5g / 10
Min., Mooney viscosity (ML _{1 + 4} , 100 ° C.) 88. (D) Ethylene-propylene copolymer rubber (EPR):
Propylene content 22% by weight, MFR (230 ° C, 2.16 kg
Load) 17 g / 10 minutes. (E) Texture improving material: (e1) Leather powder (average diameter 50μ
m), (e2) wood flour (average diameter 40 μm), (e3) cotton linter: fiber length 7 mm, fiber width 30 μm.

Example 1 The respective components in the proportions shown in Table 1 were melt-kneaded in a twin screw extruder at a resin temperature of 220 ° C. and cut with a strand cutter to obtain an olefinic thermoplastic elastomer composition. This composition was molded into a sheet to prepare a sample for measuring physical properties, and the physical properties (MFR,
JIS A hardness, breaking strength, breaking elongation, flexural modulus, scratch resistance and touch) were measured. Table 1 shows the measurement results together with the blending ratio of each component.

Examples 2 to 5, Comparative Examples 1 to 3 Using the respective 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. The results are shown in Table 1 together with the blending ratio of each component.

[0038]

[Table 1]

The methods for measuring the physical properties shown in Table 1 are as follows. (1) MFR (g / 10min): Measured at 230 ° C and 2.16kg load. (2) JIS A hardness: Measured according to JIS K6301. (3) Breaking strength (kg / cm ² ): Measured according to JIS K6301. (4) Elongation at break (%): Measured according to JIS K6301. (5) Flexural modulus (kg / cm ² ): Measured according to JIS K7203.

(6) Scratch resistance: A flat plate sample prepared from the composition was rubbed with a nail and visually evaluated according to the following criteria. ⊚: No whitening and almost no streaks can be confirmed. ◯: Whitening does not occur, and thin lines remain, but it is not recognized when observed at different angles. X: Clear streaks are formed, and streaks are observed even when observed at different angles.

(7) Tactile sensation: A sample of a flat plate prepared from the composition was evaluated by the tentacle and visual inspection according to the following criteria. ⊚: Soft, supple, moderately rough, and completely smooth on the surface. ◯: Soft and supple, with a moderately rough feeling, but with a weak and slippery surface. X: A material that is hard and difficult to bend, and has a slippery surface, or that a tactile-feel improving component is found to be removed from the resin flat plate surface.

As is clear from Table 1, the compositions of the present invention (Examples 1 to 5) are excellent in touch and scratch resistance, and also have good breaking strength, breaking elongation, flexural modulus and JIS A hardness. It can be seen that the physical properties are well balanced as compared with Comparative Examples 1 to 3.

[0043]

The olefinic thermoplastic elastomer composition for an air bag cover material of the present invention comprises (a) a polypropylene resin, (b) low density polyethylene, and (c).
Ethylene-propylene-non-conjugated diene copolymer rubber,
(D) In the olefinic thermoplastic elastomer composition component containing ethylene-propylene copolymer rubber,
(E) An olefinic thermoplastic elastomer composition for an air bag cover material, which comprises at least one component selected from leather powder, wood powder and organic fibers. The composition for an air bag cover material of the present invention, when used as an air bag cover, has sufficient scratch resistance without coating the surface, and surface characteristics (appearance) suitable for mounting in a vehicle, particularly excellent in touch, It is surely destroyed during operation, and fragments do not scatter without using auxiliary materials such as nets,
It operates reliably in a wide temperature range, maintains flexibility, and has excellent moldability.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 89/06 LSF C08L 89/06 LSF 97/02 LSW 97/02 LSW

Claims (3)

[Claims] 1. (a) Polypropylene resin 30 to 40
% By weight, and (b) 10-20% by weight of low density polyethylene.
And (c) 10 to 40% by weight of ethylene-propylene-non-conjugated diene copolymer rubber, and (d) 10 to 30% by weight of ethylene-propylene copolymer rubber, an olefinic thermoplastic elastomer composition component An olefinic thermoplastic elastomer composition for an air bag cover material, which comprises 10 to 50 parts by weight of (e) at least one component selected from leather powder, wood powder and organic fibers, relative to 100 parts by weight. 2. The polypropylene resin (a) is (a)
1) 10 to 50% by weight of homopolypropylene and (a2) 50 to 90% by weight of propylene-ethylene random copolymer
An olefinic thermoplastic elastomer composition for an air bag cover material according to claim 1, which comprises: 3. The homopolypropylene of component (a1) has a melt flow rate (230 ° C., 2.16 kg load) of 50 to 15
0 g / 10 minutes, the propylene ethylene random copolymer of the component (a2) melt flow rate (230 ℃,
2.16 kg load) 20 to 120 g / 10 minutes, the low density polyethylene of the component (b) has a melt flow rate (230
℃, 2.16kg load) 20-100g / 10 minutes,
The ethylene-propylene-non-conjugated diene copolymer rubber as the component (c) has a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 30 to
The olefin-based heat for an air bag cover material according to claim 2, wherein the ethylene-propylene copolymer rubber as the component (d) has a melt flow rate (230 ° C, 2.16 kg load) of 5 to 30 g / 10 minutes. Plastic elastomer composition.