JPH04201648A - Air bag - Google Patents

Abstract

PURPOSE:To reduce the shock for a driver's face by laminating a not-yet- extended film having a breakage elongation of 300% or more and a thickness of 100mu or less, and a biaxial oriented film having a breakage elongation of 150% or less and a thickness of 100mu or less. CONSTITUTION:An air bag 15 formed by laminating a not-yet-extended film having a breakage elongation of 300% or more and a thickness of 100mu or less and a biaxial oriented film having a breakage elongation of 150% or less and a thickness of 100mu or less. Since the shock applied to a face by the air bag is little, the air bag having the little rate of danger that the collision with a vehicle structure article due to the repulsion by the air bag is generated and a driver is wounded can be supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in an airbag that is inflated in the event of a collision of a vehicle, such as an automobile, to absorb the impact and protect a seated occupant.

[Background Art] In recent years, the practical use of airbags for ensuring the safety of occupants in automobiles has rapidly increased.

In the event of a car crash, an airbag sensor receives the shock of the collision and generates high-temperature, high-pressure gas.This high-temperature, high-pressure gas momentarily inflates the airbag, causing damage to the occupants, especially the occupants during the collision. It is intended to protect the face.

Conventionally, airbags are made of plain fabric using 4oo to 1ooo denier nylon 6 or nylon 6.6 filament yarn, and in order to improve the properties such as heat resistance, flame retardance, and air barrier properties of the plain fabric, They were made by coating the laminated base fabric with an elastomer such as synthetic rubber or natural rubber such as chloroprene or chlorosulfonated olefin, and then cutting and sewing the laminated base fabric.

Until the airbag is activated, it is stored in a narrow space such as the steering wheel or instrument panel, and its storage volume is small. Therefore, the base fabric is soft, light, and thin. It is said to be more desirable. However, conventional airbags are coated with and laminated with elastomer to a certain degree of thickness in order to improve the airbag properties, making them thick, heavy, and hard to the touch, making them difficult to fold and difficult to store.・
The storage capacity is large, and when the gas expands instantaneously due to high temperature and high pressure gas, the collision force against the human body, especially the face, is strong, and when it collides with the airbag, it receives repulsion and may collide with the vehicle structure again, resulting in injury. There was also.

To solve this problem, Japanese Patent Application Laid-Open No. 1-317847 discloses a method in which a plurality of perforated plastic films are laminated so that the positions of the holes in each film are shifted, and a laminating agent is filled in the holes. An airbag sheet made of a laminated sheet has been proposed.

Furthermore, Japanese Patent Laid-Open No. 2-31965 proposes an airbag device made of an aromatic polyamide film.

[Problems to be Solved by the Invention] The former sheet can have a smaller storage volume than conventional airbags by being thinner and lighter; Since a plurality of films are filled with adhesive and laminated, the adhesive is exposed from the film, resulting in significantly poor workability during manufacturing. Furthermore, if we were to laminate perforated plastic films so that the positions of the holes in each film would be shifted, it would be necessary to laminate about 10 films, which would result in an extremely complicated process and high cost. However, if a large number of films are bonded together using an adhesive, the result is a hard sheet, which has the drawback of being likely to end up with a large impact force.

In addition, airbags using aromatic polyamide films used in the latter airbag devices are preferable in terms of heat resistance, small size, and weight reduction, but tear strength is extremely low, and the film If there were minute scratches, it would be extremely easy to tear and would lack reliability as an airbag. Films generally have higher tensile strength per unit thickness than cloth, but their tear strength is lower, so regular films cannot provide the mechanical strength required for airbags. was there.

In view of the drawbacks of conventional airbags, an object of the present invention is to maintain mechanical and thermal properties as an airbag,
The purpose is to provide an airbag that is lightweight, has a soft texture in the basement, is easy to store, is easy to process, is inexpensive, and is small in impact, especially to the face, when the airbag is momentarily inflated. .

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration.

That is, the airbag of the present invention includes an unstretched film with a breaking elongation of 300% or more and a thickness of 100 μm or less, and a breaking elongation of 1
It is characterized by laminating biaxially stretched films with a thickness of 50% or less and a thickness of 100μ or less.

[Function] The material of the film used in the present invention is not particularly limited, and includes polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polycarbonate, nylon 6, aromatic polyamide, polyimide, polyurethane,
polyphenylene sulfide, tetrafluoroethylene,
Ethylene trifluoride and the like can be used.

In the present invention, an unstretched film and a biaxially oriented film made of these materials are laminated via an adhesive. Either film may be placed on the front side, but the unstretched film side is placed on the face side. This arrangement is preferable because it can further reduce the impact on the face when the airbag is inflated. From this point of view, it is preferable that the biaxially stretched film has high tensile strength and thermal properties. Group polyamides and the like are preferably used.

On the other hand, the unstretched film preferably has high impact strength and tear strength and is soft, and polyethylene terephthalate, nylon 6, etc. are preferable.

The thickness of the film in the present invention is 100 μm or less for both the unstretched film and the biaxially stretched film.

When the thickness of the film exceeds 100 μm, the film becomes heavy, thick, and has a hard texture, so the storage volume as an airbag becomes large, and the impact force on the face when the airbag is inflated becomes large.

In addition, regarding the elongation of the film, the required characteristics are different between a biaxially stretched film and an unstretched film.

It is necessary that the elongation at break is 300% or more for an unstretched film and 150% or less for a biaxially stretched film.

That is, since the unstretched film is basically arranged on the surface side, it has high impact strength and tear strength, and is preferably soft, so if the elongation at break is less than 300%, the impact strength, The tear strength is low and the texture is hard, resulting in a large impact force on the face when the airbag is inflated.

On the other hand, since the biaxially stretched film is basically placed on the inner surface, it is preferable to use one with high tensile strength and thermal properties, so if the elongation at break exceeds 150%, it depends on the material of the film. , the tensile strength is low, and the airbag becomes extremely stretchable, and the volume is not determined when the airbag is inflated, so the time required for the airbag to inflate changes, resulting in a serious defect as an airbag. do not have.

The present invention makes use of the characteristics such as the softness of an unstretched film alone and the mechanical properties of a biaxially stretched film alone, and in particular, by laminating films with different elongations, the tear strength is significantly increased. It is based on new knowledge that improves performance. In order to improve the tear strength, it is preferable that the elongation at break of the laminated films differ by 150% or more.

The two types of films of the present invention exhibit excellent effects when simply laminated (non-adhered), but even more excellent effects are obtained when they are partially or fully adhered.

That is, when laminated in an unadhered state, a biaxially stretched film functions in terms of mechanical conditions, and an unstretched film functions in terms of contact characteristics to the face. In that case,
When both are independent, that is, not bonded, each can move freely, and even if the unstretched film comes into contact with the face, it acts as a shock absorber against the impact of the inner biaxially oriented film, and also acts as a shock absorber against friction. It is characterized by its ability to easily follow the movement of the face even when the face is moved.

In addition, when both are partially bonded, excellent functions similar to those in the case where they are not bonded are exhibited, and the mechanical properties are significantly improved, although not as much as in the case where they are fully bonded.

The above explanation mainly concerns the lamination arrangement of an unstretched film and a biaxially stretched film in which the former is laminated on the outside. Alternatively, a three-layer laminated structure may be used.

The adhesive used in the present invention depends on the material, softness, and peeling strength of the film used, but for example, polyurethane-based, polyester-based, or polycarbonate-based adhesives can be used.

The amount of adhesive applied varies depending on the adhesive structure, but
In any case, it is preferable to use as little as possible as long as the necessary peeling strength can be obtained from the viewpoints of thinning, weight, and texture of the airbag.

[Example] Next, the present invention will be further explained by examples.

In addition, the physical property values in Examples were measured by the following method.

(1) Weight per unit area of JIS L-1096 was measured.

■ Thickness Measured according to JIS l-1096.

(3) Bending resistance Measured by JIS L-1096 (45° cantilever method).

(4) Tear strength Measured according to JIS L-1096 (single tongue method).

(5) Impact resistance to the human body Cut and sew the softened and crimped fabric to a radius of 34°5cm.
A circular airbag is made, and a hole with a radius of 4 ann is drilled as an inflator attachment part. Next, as shown in FIG. 1, an ultra-thin rubber balloon is placed inside the airbag and inflated with air until the internal pressure reaches 0.2 kg/cut. Next, a 500g lead pendulum attached to the end of a 1m long string was allowed to hang down naturally, and the pendulum was set so that it came into close contact with the center of the airbag.
The pendulum is then pulled away from the airbag to a 45° position and released from there to collide with the airbag. Measure the angle at which the pendulum returns due to the airbag's repulsion.

This return angle was evaluated as the degree of impact.

Example 1 Unstretched film, elongation at break 420%, thickness 50%
A polyethylene terephthalate film having a breaking elongation of 110% and a thickness of 50 μm was prepared as a biaxially stretched film and a polyethylene terephthalate film having a breaking elongation of 110%, respectively, and these films were laminated using a polyurethane adhesive. The evaluation results of various physical properties are shown in Table 1.

A bag was formed using two of the above-mentioned laminated films with the unstretched film layer facing outside, and an opening for attaching an inflator was formed in the center of one of the bags to obtain an airbag.

The impact resistance of this airbag to the human body was measured and shown in Table 1.

Example 2 Unstretched film, elongation at break 510%, thickness 60μ
A polyethylene terephthalate film with a breaking elongation of 110% and a thickness of 50 μm was prepared as a polyurethane film and a biaxially stretched film, respectively, and laminated with a polyurethane adhesive to form an airbag in the same manner as in Example 1. Various physical properties and impact resistance to the human body were evaluated, and the results are shown in Table 1.

Comparative Example 1 An unstretched film made of polyethylene terephthalate with a breaking elongation of 450% and a thickness of 70 μm was produced. Table 1 shows the evaluation results of various physical properties and the evaluation results of the airbag formed with this film.

Comparative Example 2 A biaxially stretched film made of polyethylene terephthalate with a breaking elongation of 120% and a thickness of 60 μm was produced. Table 1 shows the evaluation results of various physical properties and the evaluation of the airbag formed with this film.

Comparative Example 3 Unstretched film, elongation at break 450%, thickness 125
A polyethylene terephthalate film having a breaking elongation of 115% and a thickness of 125 μm was prepared as a biaxially stretched film and laminated with a polyurethane adhesive. Table 1 shows various physical properties and evaluation results of the airbag formed with this laminated film.

Comparative Example 4 Unstretched film, elongation at break 420%, thickness 50μ
A polyethylene terephthalate film having a breaking elongation of 170% and a thickness of 50 μm was prepared as a biaxially stretched film and laminated with a polyurethane adhesive. Table 1 shows various physical properties and evaluation results of the airbag made of this laminated film.

Comparative Example 5 840 denier, 136 filament nylon 6.6
A plain weave with a warp yarn density and a weft yarn density of 25 yarns/inch was obtained using the same method, followed by scouring, drying, and intermediate setting in a conventional manner. Next, 99g/nf of chloroprene rubber was applied,
An airbag was formed using the obtained coated fabric. Table 1 shows various physical properties and evaluation results of the airbag.

As is clear from Table 1, Examples 1 to 2 are lighter, thinner, and have a softer texture than Comparative Examples 1 to 5.
Moreover, the impact resistance on the human body was small, making it extremely desirable as an airbag.

Examples 3 to 4 The same unstretched film and biaxially stretched film as in Example 1 were prepared, and polyurethane adhesive was used to adjust the pore size to −mmφ.
A laminated film was obtained by partially adhering the parts using an intermittent coater with a pitch of 5 mm.

An airbag was made using this laminated film in the same manner as in Example 1 (Example 3).

On the other hand, as Example 4, an airbag was produced by simply laminating the two types of films described above without adhering them together, and the rest was carried out in the same manner as in Example 1 (Example 4).

The impact resistance of these airbags to the human body was measured and the results are shown in Table 2.

As is clear from Table 2, the airbags of Examples 3 and 4 were both thin, soft, and had excellent storage properties, and had low impact resistance to the human body.

Table 2 [Effects of the Invention] Since the airbag of the present invention has a small impact on the face, it is possible to provide an airbag with a low risk of injury caused by collision with a vehicle structure due to repulsion from the airbag 1. can. Further, the airbag of the present invention is lightweight, has a thin surface, has a soft texture, and has excellent storage properties, so that steering wheels and instrument panels can be made smaller. Furthermore, the airbag of the present invention is less expensive to manufacture than conventional airbags, and can promote widespread use of personnel protection systems using airbags.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a method for measuring the impact resistance of an airbag according to the present invention. Patent applicant Toshi Co., Ltd.

Claims (5)

[Claims] (1) An airbag characterized by laminating an unstretched film with a breaking elongation of 300% or more and a thickness of 100 μm or less, and a biaxially stretched film with a breaking elongation of 150% or less and a thickness of 100 μm or less. (2) The airbag according to claim (1), wherein both films are laminated in a non-adhesive state. (3) The airbag according to claim (1), wherein both films are laminated via an adhesive. (4) The airbag according to claim (3), wherein an adhesive is partially applied. (5) Claim (1) characterized in that the unstretched film is made of polyethylene terephthalate or nylon 6.
Airbags listed.