JPH11227550A - Air bag for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air bag for automobile having such sticking characteristics between base cloths as excellent in heat resistance and temperature stability and a practicable sticking strength in the air bag formed by connecting the peripheral edges of the base cloths to each other through the layer of an adhesive agent. SOLUTION: In an air bag for automobile formed by connecting the peripheral edge parts of base cloths to each other by sticking, the base cloths (woven cloth 13) are provided, on a coated surface side, with heat resisting coated layers 18 formed of a heat cure type silicone rubber coating, and an adhesive agent layer 14 formed of a heat cure type silicone rubber adhesive agent is provided between the heat resisting coated layers 18 and 18. Also it has a T separation preventing sticking strength (pulling speed: 100 mm/min) of 150 N/25 mm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag for an automobile in which the peripheral edges of a base fabric formed of a woven fabric are joined by bonding.

[0002]

2. Description of the Related Art An automobile is equipped with an airbag device for protecting an occupant. In the airbag device, the airbag is usually assembled with an inflator in an airbag case or the like.

[0003] The airbag has been formed into a bag shape by sewing together base fabrics having a heat-resistant coating layer formed on an inner surface. This heat-resistant coating layer is for protecting the base fabric from high-temperature inflation gas ejected from the inflator.

On the other hand, recently, some airbags are required to have an inflation characteristic capable of maintaining the internal pressure of the airbag at a predetermined level or more immediately after the operation of the inflator.

[0005] In the sewing airbag described above, leakage of inflation gas from the sewing site occurs, and it is difficult to satisfy the required characteristics. Therefore, the seam (usually on the inside)
However, the number of man-hours required for sewing and coating and hardening of the sealing material were increased, resulting in an increase in the number of manufacturing steps as a whole.

For this reason, the bonding between the base fabrics is bonded (joined).
It can be considered that Various techniques relating to an airbag manufactured by bonding the base fabrics to each other by heat welding have been proposed (JP-A-2-162134, 3-7).
337, 5-77342, 6-199198, 9-11
No. 9066).

[0007]

However, in the bonding by heat welding (thermal fusion), since a thermoplastic resin is usually used as an adhesive layer, heat resistance and temperature stabilization are required at a joint (joint) of an airbag. It is difficult to obtain sex.

For this reason, as described in JP-A-4-356248 (paragraph "0014"), a heat-curable silicone-based paint having excellent heat resistance and temperature stability is used, and heat is applied. It is conceivable to use a curable silicone adhesive.

However, as described in this publication, the materials (synthetic fibers) forming the base fabric are nylon (polyamide) and tetron (polyethylene terephthalate).
On the other hand, silicone represented by polydimethylsiloxane is a non-polar material, whereas the latter is usually difficult to adhere to the former. For example, in the solubility parameter (SP value: index of mutual wettability),
Nylon 66: 13.4, polyethylene terephthalate: 10.7, whereas polydimethylsiloxane: 7.3 to 7.6. The difference in SP value between the two, especially between nylon and silicone, is large ( "Adhesion Handbook (2nd edition)" edited by Japan Adhesion Association (Showa 55-11-1)
0) See p.618).

[0010] For this reason, it has been considered difficult to obtain a practical adhesive strength by forming the heat-resistant coating layer with a general-purpose silicone rubber-based paint and further bonding using a silicone rubber-based adhesive.

In view of the above, the present invention provides an automotive airbag in which the peripheral edges of a base fabric are bonded via an adhesive layer, and the adhesive properties between the base fabrics are excellent in heat resistance and temperature stability. It is another object of the present invention to provide an airbag for an automobile which exhibits practical adhesive strength.

[0012]

SUMMARY OF THE INVENTION An automobile airbag according to the present invention solves the above-mentioned problems by the following constitution.

[0013] In an airbag for an automobile in which the peripheral portions of a base fabric formed of a woven fabric are joined by bonding, the mode of bonding is such that the base fabric is formed of a silicone rubber-based paint on the surface to be adhered. And a T-peel adhesive strength (tensile speed: 100 mm / min) of 150 N / 25 mm or more with an adhesive layer formed of a silicone rubber-based adhesive between the heat-resistant coating layers. There is a feature.

It is desirable to form a silicone rubber-based paint into the woven fabric to form the heat-resistant coating layer. The heat-resistant coating layer is diluted with a solvent while applying a tensile force of 48 N / m or more to the woven fabric. The silicone rubber-based paint can be easily formed by knife coating.

Further, in the airbag having the above-mentioned structure, the woven fabric is formed of polyamide-based fibers, and the silicone rubber-based paint is obtained by blending a general-purpose silicone rubber with a silane coupling agent and an organic peroxide, Further, a configuration in which the silicone rubber-based adhesive is at least based on a silicone rubber based on a vinyl group / polar functional group-introduced silicone rubber is further used, and the silane coupling agent is epoxy silane; It is desirable that the polar functional group of the functionalized silicone rubber be an epoxy group.

[0016]

Next, an embodiment of the present invention will be described with reference to the drawings.

(1) Here, as shown in FIG. 1, an adhesive layer 14 is formed on the peripheral edge and the center of an unfolded base cloth 12 formed of a woven cloth, and a head as shown in FIG. The case where the protection airbag B is manufactured will be described as an example. The present invention is applicable to a case where a plurality of base cloths (the former is usually two sheets and the latter is usually three sheets) are bonded and bonded to each other, as in the case of other airbags for steering wheels and passenger seats. Can of course be applied.

In the following description, a blending unit is a weight unit unless otherwise specified.

In the airbag of the present embodiment, a peripheral portion of a base cloth 12 made of a woven cloth is connected via an adhesive layer 14. Naturally, the air blowing port forming part 16 of the base cloth 12 is excluded.
At this time, the width of the adhesive layer 14 is usually set to 10 to 20 mm.

At this time, the joining may be performed either without the reinforcing cloth as shown in FIG. 3 or with the reinforcing cloth 15 as shown in FIG. At the time of inflation, the peeling action mainly acts on the adhesive layer 14 in the case of FIG. 3, and the shearing action mainly acts on the adhesive layer 14 in the case of FIG.

The woven fabric used as the base fabric 12 is made of polyamide (aliphatic polyamide, aromatic polyamide, alicyclic polyamide), polyester (ex. Polyethylene terephthalate), polyvinyl alcohol (vinylon), or the like. The one using a polar synthetic fiber which is easy to obtain heat resistance and strength is used. Of these, aliphatic polyamide fibers typified by nylon 6 and nylon 66 are desirable because of the balance between price and physical properties.

The form of the woven fabric 13 satisfies the predetermined strength required for the airbag, and when the silicone heat-resistant coating layer 18 described later is formed,
It suffices that the surface 8 has a rough surface that can penetrate the woven fabric (see FIG. 5).

For example, in the case of nylon 66, for example, the thickness of the thread is 420 d, the number of shots is 49 threads / 25.4 mm,
And plain weave.

(2) The base fabric 12 has a heat-resistant coating layer 18 formed of a heat-curable silicone rubber-based paint on the surface to be adhered (the inner surface). This silicone rubber-based paint has a predetermined heat resistance and a T peel adhesion strength of 150 N / 25 mm or more (pulling speed 100 mm / min, below) when the base fabric 12 is adhered through the adhesive layer 14. the same)
Are not particularly limited. The above-mentioned adhesive strength can be easily achieved by forming a heat-resistant coating layer 18 by infiltrating a silicone rubber-based paint into the cloth of the woven fabric 13 (see FIG. 5).

In order to obtain the above-mentioned T-peel strength, the silicone rubber-based paint is preferably one based on a peroxide-cured rubber compound obtained by blending a silane coupling agent with a general-purpose silicone rubber. An auxiliary material such as carbon black may be compounded in the rubber compound.

As the general-purpose silicone rubber, dimethyl silicone rubber, methyl phenyl silicone rubber, methyl vinyl silicone, etc. used for heat curing (heat vulcanization) can be preferably used. From a viewpoint, a silicone rubber in which a vinyl group is introduced, and further, a phenyl group is introduced is desirable in view of low-temperature characteristics.

[0027] The silane coupling agent is blended in order to ensure adhesion to the woven fabric which is a polar material. The amount of the silane coupling agent is usually 0.5 to 5 parts, preferably 1 to 3 parts, per 100 parts of silicone rubber.
The silane coupling agent improves the wettability of the silicone rubber-based coating material, which is a non-polar material, with respect to the woven fabric 13 made of the polar material forming the base fabric 12 by the action of a surfactant, and at the time of heating. In the above, when the woven fabric is a polyamide, it is presumed that a chemical bond is formed by performing a dehydration reaction or the like with the active hydrogen of the amide bond, thereby contributing to an increase in adhesiveness.

As the silane coupling agent, epoxy silane, amino silane, mercapto silane and the like are optional. Of these, epoxysilane is preferred because of its high reactivity.

The organic peroxide is used to vulcanize the silicone rubber to provide a predetermined heat resistance and strength, and to cooperate with the silane coupling agent to secure the adhesiveness to the woven fabric. It is blended in order to give the effect of partial cross-linking with the silicone rubber-based adhesive layer. The amount of the organic peroxide is usually 0.5 to 5 parts, preferably 1 to 3 parts, per 100 parts of the silicone rubber. As organic peroxides, benzoyl peroxide (BPO), subs-2,4-dichlorobenzoyl peroxide (2,4DC
B), dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP) and the like can be suitably used. Of these, 2,4DCB is particularly preferred because it is activated at a lower temperature than other organic peroxides and contributes to the adhesive action.

The silicone rubber-based coating composition has a suitable viscosity with a non-polar organic solvent (usually SP value of 9 or less), for example (toluene: SP value: 8.90), and a viscosity of 20,000 to 2
It is adjusted to 5000 cP (20 to 25 Pa · s) and used.

The coating method may be dip coating or the like, but a knife coat as shown in FIG. 6 is desirably used to ensure penetration into the eyes of the woven fabric. It is desirable to do it. The tension is mainly applied by the pulling speed of the winding roller 20 and the tension rollers 22 and 24. The application amount is mainly adjusted by adjusting the angle of the doctor knife 26. In addition, 28 is a feeding roller, and 29 is a drying oven.

The tension at this time depends on the viscosity of the paint, but is usually applied by applying a tension of 48 N / m or more. If it is less than this, it may be difficult to obtain a predetermined adhesive strength.

The coating amount of the paint is 3% in solid content.
0 to 100 g / cm ² , preferably 40 to 60 g / m ²
And If the amount is too small, it is difficult to obtain heat resistance of the base cloth, and if it is too large, it becomes difficult to obtain a predetermined adhesive strength.

(3) As the silicone rubber-based adhesive, a T peel adhesion strength of 150 N / 25 mm or more (pulling speed 100 mm / min, the same applies hereinafter) in cooperation with the heat-resistant coating layer.
Are not particularly limited.

As the silicone rubber-based adhesive, a silicone rubber-based coating film after heat curing (vulcanization) together with a vinyl group having polymerizability (the silane coupling agent and the organic peroxide remain). It is preferable to use a material in which a polar functional group such as a glycidyl group (epoxy group), a carboxyl group, an amino group, or a hydroxyl group, which exhibits an adhesive action (wetting and / or reactivity), is appropriately introduced. .

More specifically, a one-part heat-curable silicone adhesive manufactured and sold by Shin-Etsu Chemical Co., Ltd. under the trade name "KE1820" can be mentioned.

The method of applying the silicone rubber-based adhesive is not particularly limited. For example, the application is performed by nozzle application using an air gun. The coating amount of the silicone rubber-based adhesive is usually 500 to 600 g / m ² in terms of solid content.
And

[0038]

EXAMPLES Examples performed to confirm the effects of the present invention will be described below together with comparative examples.

(1) Preparation of the base cloth The woven cloth was a plain weave (49 to 25.4 mm in number of shots) using nylon 66 thread (420 d) (thickness: 320 to 330 μm).

A heat-vulcanizable silicone rubber-based coating material (methyl vinyl polysiloxane rubber: 100 parts, glycidoxypropyltrimethoxysilane: 5 parts, 2,4 DCB: 3 parts) is added to the above-mentioned 2 m wide band-shaped woven fabric. A quantity of 100 parts was diluted with 200 parts of a hydrocarbon solvent (toluene) and the viscosity was 22 Pa.
・ Adjust to s and apply the tensile force shown in Table 1, respectively.
Knife coating was performed so that the coating amount was 50 g / m ^2, and then drying was performed at 160 ± 5 ° C for 2 minutes.

(2) Peeling Strength Test The coated base fabric was cut into a size of 200 mm long × 100 mm wide, and the surface was wiped with toluene and left at room temperature for 1 hour to prepare a base fabric 30 for lamination. Using the base fabric 30 for lamination, a test piece (adhesive laminate) 31 for a peel test was prepared as follows (see FIG. 7).

Incidentally, an iron pressing plate 32 (200 mm × 200 mm × 1.0 mm) for preparing the adhesive laminate 31 was prepared.
t) and a release sheet 33 made of a fluororesin sheet
(200 mm × 200 mm × 0.05 mmt), and a pair of first spacers 34 each of 1.0 mmt made of iron, and
0.5 mmt second and third spacers 35 and 36 were prepared.

The release sheet 33 is placed on the pressing plate 32.
, And the base fabric 30 for lamination is placed on the heat-resistant coating layer. Then, as shown in the figure, the first spacer 34 is placed on both ends of the press contact plate 32 and the second spacer 35 is placed on one end of the base fabric 30 for lamination, and the third spacer 35 is placed 150 mm from the second spacer 35. Place 36.

Heat-curable silicone rubber adhesive A
("KE1820" manufactured by Shin-Etsu Chemical Co., Ltd.) is applied in an H-shape by about 9 g, and the above-mentioned laminating base fabric 30 is placed thereon with the heat-resistant coating layer facing down. Here, a laminate unit for press is prepared.

The lamination unit for press is mounted on a press 3
7 for 1 minute (press pressure: 10 kgf (98N),
Thereafter, the stacking unit for press is removed from the press machine 37 and heated in a thermostat at 150 ° C. × 60 min.

The pressing plate 32 is removed from the pressing lamination unit, and is left to cool at room temperature with the release sheet 33 remaining. Thereafter, the release sheet 33 is removed, and 25
The test piece 38 (4 pieces each) is prepared by cutting to a width of mm.

Each of the test pieces prepared above was subjected to a T peel strength test (tensile speed 100 mm /
min) and tensile shear strength (tensile speed 100 mm / min)
Was measured.

Comparative Example 2 is the same as Example 1
The peel test was performed on an adhesive laminate having a configuration in which the heat-resistant coating layer and the adhesive layer did not come into contact with each other on the opposite side of the laminating base fabric used in Example 1.

(3) Inflation test In the same manner as in the peel strength test, the peripheral cross-section was as shown in FIG.
Alternatively, an inflation test was performed on the airbag of the embodiment shown in FIG. 2 manufactured by bonding and bonding in the embodiment shown in FIG. 4 by the following method.

The inflator 40 was placed in the diffuser can 41, the airbag B was mounted, and the mounting opening was fastened with metal fittings to examine the presence or absence of peeling when the inflator exploded (see FIG. 2).

(4) Test Results / Evaluation The results are shown in Table 1. The examples of the present invention are remarkably superior in peel strength as compared with Comparative Examples 1 and 2, and even in the inflation test, It can be seen that peeling did not occur and that it had a sufficient practical adhesive strength.

[0052]

[Table 1]

[0053]

The operation and effect of the present invention are as follows.
The base fabric is provided with a heat-resistant coating layer formed of a silicone rubber-based paint on the surface to be adhered, and a configuration in which an adhesive layer formed of a silicone rubber-based adhesive is interposed between the heat-resistant coating layers, and
T peel adhesion strength of 150N / 25mm or more (pulling speed 1
With the configuration shown in the figure, the adhesive properties between the base fabrics are excellent in heat resistance and temperature stability, and show practical adhesive strength.

The adhesive strength can be easily obtained between the joining of the base fabrics by forming the heat-resistant coating layer by injecting the silicone rubber-based coating material into the woven fabric and forming the heat-resistant coating layer. More preferably, the penetration of the silicone rubber-based paint into the woven cloth is performed by knife coating while applying a tensile force of 48 N / m or more to the woven cloth.

In the above construction, the woven fabric is formed of polyamide fibers, and the silicone rubber-based paint is a solvent-based paint obtained by adding a silane coupling agent and an organic peroxide to general-purpose silicone rubber. And the silicone rubber of the silicone rubber-based adhesive has a vinyl group /
This can be more easily achieved by the constitution of the polar functional group-introduced silicone rubber.

[Brief description of the drawings]

FIG. 1 is a development view of a base fabric used for manufacturing a head airbag which is an example of an airbag to which the present invention is applied.

FIG. 2 is a partial cross-sectional view of a head airbag manufactured using the base fabric of FIG. 1;

FIG. 3 is a cross-sectional view showing one joining mode of the base fabrics of the airbag.

FIG. 4 is a cross-sectional view showing another bonding state of the base fabrics.

FIG. 5 is a model diagram showing a bonding mode of a woven fabric / heat-resistant coating layer / adhesive layer.

FIG. 6 is a flowchart in the case of forming a heat-resistant coating layer on a base fabric of the present invention by knife coating.

FIG. 7 is a flowchart showing a method of preparing a test piece in a test example of the present invention.

[Explanation of symbols]

 12 base cloth 13 woven cloth 14 adhesive layer 17 heat-resistant coating layer

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Akira Mabuchi 1 Ochiai Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyota Gosei Co., Ltd. In company

Claims (5)

[Claims] 1. An automobile airbag in which peripheral edges of a base fabric formed of a woven fabric are bonded by bonding, wherein the bonding is performed by a heat-curable silicone rubber-based silicone rubber base fabric on the surface to be adhered. A heat-resistant coating layer formed of a paint is provided, and an adhesive layer formed of a heat-curable silicone rubber-based adhesive is interposed between the heat-resistant coating layers, and 150
T / peel adhesion strength of N / 25mm or more (pulling speed 100mm
/ Min). 2. The airbag for an automobile according to claim 1, wherein the heat-resistant coating layer is formed by penetrating a silicone rubber-based paint into the cloth of the woven fabric. 3. The heat-resistant coating layer is formed by knife-coating the silicone rubber-based paint diluted with a solvent while applying a tensile force of 48 N / m or more to the woven fabric. Item 4. An airbag for a vehicle according to Item 2. 4. The woven fabric is formed of polyamide-based fibers, and the silicone rubber-based coating is a solvent-based coating obtained by adding a silane coupling agent and an organic peroxide to general-purpose silicone rubber. The automotive airbag according to any one of claims 1 to 3, wherein the silicone rubber of the silicone rubber-based adhesive is at least a vinyl group / polar functional group-introduced silicone rubber. 5. The automotive airbag according to claim 4, wherein the silane coupling agent is epoxy silane, and the polar functional group of the vinyl group / polar functional group-introduced silicone rubber is an epoxy group.