KR960002431B1 - A pad for use in an air bag device - Google Patents

Abstract

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Description

Pad for Airbag Unit

1 is a partial longitudinal sectional view of a state in which a pad showing an example of the present invention is attached to an airbag apparatus.

2 is an enlarged cross-sectional view of part II of FIG. 1;

3 is a plan view of the pad of FIG.

* Explanation of symbols for main parts of the drawings

11: airbag device 13: pad body

15: air bag 17: upper wall of the pad body

19: groove portion for development 21: circumferential wall portion of the pad body

t: Residual thickness of the unfolding groove part α : Inner opening angle of the unfolding groove part

[Industrial use]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pad covering an upper surface of an airbag device mounted on a steering wheel of an automobile or an instrument panel in front of a passenger seat, and in particular, an airbag device which is a monolayer molded body of a thermoplastic elastomer (hereinafter referred to as TPE) that can be produced with high productivity. It relates to a pad.

[Prior art]

Conventional airbag device pads are usually manufactured as follows.

The pad is usually manufactured by using a polyurethane material for reaction injection molding (RIM) in a foaming prescription and by injection molding by embedding a net insert. The net insert is for reinforcing the pad upper wall during airbag operation.

However, in the case of the manufacturing method, since the net insert is used, the set work is necessary and the number of production processes is increased. ② Polyurethane material used for RIM molding is thermosetting, so there is a problem that the material cannot be recycled.

For example, for example, Japanese Patent Application Laid-Open No. 3-189252 discloses a skin layer formed of a soft first resin material (styrene-based TPE) and a second resin material (olefin resin) that is harder than the first resin material. The pad in which the core layer which is formed is integrally formed is proposed.

[Problems to Solve Invention]

However, in the case of the pad having the above structure, the core layer is formed separately, and the core layer needs to be insert-molded after the skin layer as the insert, so that the number of manufacturing steps increases and the mold structure for insert molding also becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide a pad for an airbag device, in which the core layer is not molded separately and there is no need for insert molding, the number of manufacturing steps can be greatly reduced, and the injection molding mold is simplified. It is done.

[Means for solving the problem]

The pad for airbag apparatus which concerns on this invention can solve the said subject by the following structures.

A pad covering the upper surface of the airbag apparatus, the pad body being continuously provided with a groove for deployment that breaks when the airbag is inflated to allow the upper wall to be deployed, wherein the pad body has a low tensile strength T _B (-35 ° C.). ): Styrene-based TPE or polyester-based TPE of 200 to 500 kgf / cm 2 (19.6 to 49 MPa), which is formed into a single layer so that the average thickness of the upper wall is 2.5 to 6 mm; It is characterized by being 1.5 mm.

EXAMPLE

Next, the Example of this invention is described based on drawing.

A. First, the basic configuration will be described.

That is, as a pad covering the upper surface of the airbag device 11, the pad main body 13 is continuously broken when the airbag 15 is inflated so that the upper wall portion 17 can be deployed. It is a composition. The overall continuous shape of the groove 19 for development is not particularly limited, but is generally H-shaped, as shown in FIG.

B. In the above configuration, the present application has the following characteristic configuration.

⑴ The first characteristic condition is styrene-based TPE or polyester-based TPE of low tensile strength T _B (-35 ° C): 200-500 kgf / cm 2 (19.6-49 MPa), and the average thickness of the upper wall is 2.5-6 mm. It is single layer molding.

If the low temperature tensile strength is less than the numerical range, the groove 19 may be broken by the allowable external force in a normal state, and if it exceeds the numerical range, the groove may not be broken smoothly when the airbag is inflated. have.

If the average thickness of the upper wall portion is less than 2.5 mm, the shape retaining ability is not sufficient. If the average thickness exceeds 6 mm, the weight increases, which is not preferable. In addition, the average thickness of the circumferential wall portion 21 is 2.5 to 6 mm in consideration of the shape holding ability, and at the same time, as shown in FIG. 1, the inner surface of the outer circumferential portion of the upper wall portion 17 and the outer circumference of the circumferential wall portion 21. It is preferable to form the plurality of reinforcing ribs 23 therebetween.

The reason why the styrene-based TPE or the polyester-based TPE is used as the TPE is because they are excellent in low temperature impact resistance and good in thermal expansion test results.

(Iii) As the styrene-based TPE, any one of the soft segment may be SBS-based polybutadiene, SIS-based polystyrene, SEBS-based polyolefin, or the like. Of these, SEBS is preferred because it does not have a double bond between molecules and is excellent in weather resistance, abrasion resistance, heat resistance, and the like. Specifically, toughtech (made by Asahi Chemical Co., Ltd.) etc. can be used.

(Ii) As the polyester-based TPE, (1) hard segments are made of polyester such as polybutylene telephthalate, and soft segments are made of polytetramethylene glycol ether (PTMG), PTMEGT (condensation product of PTMG and telephthalic acid), respectively. Polyester polyether type made of polyether, (2) Polyester polyester type which makes hard segment the same polyester as the above, and makes soft segment into aliphatic polyester, such as polycarbrolactone, can be used. Specifically, a romoth (made by General Electric), a hydrel (made by Dupont), etc. can be used.

(2) The second characteristic state is that the remaining thickness t of the groove part 19 for development is set to 0.3 to 1.5 mm (preferably 0.5 to 1.0 mm).

If the remaining thickness is less than 0.3 mm, the groove portion 19 may be broken by the allowable external force in the state. If the thickness exceeds 1.5 mm, the groove portion 19 may not be broken smoothly when the airbag is expanded.

In addition, it is preferable at this time to make an inner side opening angle ( alpha ) into 30-90 degrees. If the inward opening angle is less than 30 °, grooves are likely to occur on the pad surface, and if it exceeds 90 °, the groove portion may not be broken smoothly during airbag operation. In addition, since the outer opening angle of the unfolding groove 19 has little influence on the unfolding action of the upper wall 17, the groove shape and the unwinding angle can be arbitrarily selected.

In addition, the site | part which becomes the hinge site | part H at the time of an upper wall part deployment is made into thickness thinner than the average thickness of the upper wall part 17 normally 2-4 mm so that a deployment part may develop easily at the time of airbag inflation.

C. The method for producing the pad is not particularly limited, but is performed as follows, for example.

In the molding die, the polystyrene-based TPE or polyester-based TPE compound is molded by injection molding as a molding material. In addition, the molded article is finished by applying a weather-resistant paint on its surface as necessary.

D. This pad is assembled by fixing the rivet 29 to the inflator 25 to which the airbag 15 arranged above the boss of the steering wheel (not shown) is attached. .

Effects of the Invention

The pad for the airbag device of the present invention is a TPE material as described above, and is a single type of TPE (styrene-based or polyester-based) having a low temperature tensile strength in a predetermined range, and at the same time, specifying the remaining thickness of the groove part for development, thereby monolayering the TPE material. Even when molded, as shown in the test example described later, no problem occurs in development performance during pad expansion.

Therefore, the pad for the airbag apparatus of this invention does not need to insert-mold and shape | mold the core layer separately conventionally. Therefore, the number of manufacturing steps is greatly reduced and the mold structure at the time of molding is simplified.

In addition, although Japanese Patent Laid-Open No. 2-171364 discloses the technical idea of single-layer molding of a pad for an airbag device with TPE, a specific kind of material having a material characteristic (low temperature tensile strength) of TPE in a specific range as in the present invention is disclosed. The idea of maintaining the development performance of the development part at the time of pad expansion by combining the configuration limited by the configuration and the configuration with the remaining thickness of the groove part for development is not specified or suggested at all.

[Test Example]

Hereinafter, the test example performed in order to confirm the effect of this invention is demonstrated.

The pad of each Example and the comparative example was shape | molded using the material shown in Table 1. Both TPE used for the comparative example is a urethane system, the comparative example 1 is a product made by "the Japan ink chemical industry", and the comparative example 2 is the "Eratran company of Japan."

Moreover, the trial specification of a pad is as follows.

Type A… Upper wall portion area: 300 cm 2, upper wall portion average thickness: 5 mm, groove portion remaining thickness for development: 1.0 mm, groove inner side opening angle for development: 60 °, type B. Upper wall area: 270 cm 2, upper wall average thickness: 4.5 mm, groove portion remaining thickness for development: 0.5 mm, groove inner side opening angle for development: 50 °

Then, the pads were mounted in an airbag apparatus similar to that in which the pads were mounted on the actual vehicle, and the expansion test was performed at each temperature of the display.

Then, visually observe the developed state of the pad and smoothly deploy the pad. 0, cracks in part of pad… Δ, pads scattered. ×, it was. Although the result was shown, although each Example has no problem in pad development property in all items in 85 degreeC atmosphere and -35 degreeC atmosphere, it turns out that there exists a problem in each comparison in -35 degreeC atmosphere.

Table 1 also records the physical property data of each material used for reference. Each physical property data is obtained by preparing test pieces.

The test method for each physical property data was performed based on ① tensile strength (T _B ): ASTM D638, ② tensile extension (E _B ): ASTM D638, ③ Izod impact strength: ASTM D256.

TABLE 1

*) Commercially Modified Material

Claims (2)

A pad covering the upper surface of the airbag device 11, wherein the pad body 13 is broken when the airbag is inflated, and is provided on a pad for an airbag device that is continuously provided with a groove portion 19 for deploying the upper wall portion 17. The pad body 13 is a styrene-based thermoplastic elastomer having a low tensile strength T _B (-35 ° C.) of 200 to 500 kgf / cm 2 (19.6 to 49 MPa), and the average thickness of the upper wall part 17 is 2.5 to It is molded so as to be 6mm, the remaining thickness of the groove portion 19 for deployment is 0.3 to 1.5mm pad for airbag apparatus, characterized in that. A pad covering the upper surface of the airbag device 11, wherein the pad body 13 is broken when the airbag is inflated, and is provided on a pad for an airbag device that is continuously provided with a groove portion 19 for deploying the upper wall portion 17. The pad body 13 is a polyester-based thermoplastic elastomer having a low tensile strength T _B (-35 ° C.) of 200 to 500 kgf / cm 2 (19.6 to 49 MPa), and the average thickness of the upper wall part 17 is 2.5. Single layer molding is performed so that it becomes-6 mm, and the remaining thickness of the said groove part 19 for deployment is 0.3-1.5 mm, The pad for airbag apparatus characterized by the above-mentioned.