JP2000170080A - Cloth for air bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain cloth for an air bag capable of readily acquiring the memory of crease and excellent in folding workability and housing property by applying a specific amount of coating agent to one side of a base fabric made of a synthetic fiber. SOLUTION: This cloth for air bag is obtained by applying a coating agent of a silicone rubber in an amount of <=20 g/m2, preferably 5-20 g/m2 expressed in terms of solid content to the one side of base fabric made of a synthetic fiber and having 1,700-2,100 cover factor, e.g. a plain weave obtained by driving polyamide 66 yarns having 420 denier fineness each in 44 numbers/inch as weft and warp. In the cloth for air bag, the thickness of the coated cloth is <=1.04 times based on the thickness of the base fabric and bending hysteresis measured by KES-FB-2 is >=0.55 gf.cm/cm based on average bending hysteresis in two directions mutually perpendicular in plane of the coated cloth, e.g. in warp direction and weft direction of woven fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag cloth which is a cloth constituting various airbags such as an airbag for a driver's seat and an airbag for a passenger's seat. More specifically, the present invention relates to an airbag cloth that tends to be folded.

[0002]

2. Description of the Related Art In general, an airbag is stored in a folded state in a storage portion provided in a central portion of a steering wheel of a vehicle or an instrument panel, and is provided at the time of a vehicle collision. In addition, the gas generated by the inflator is deployed and expanded into the vehicle compartment to receive the occupant.

As a cloth for an airbag for such an airbag, a woven cloth made of a synthetic fiber such as a polyamide fiber is generally used. Since it inflates and receives the occupant, the airbag cloth is required to have gas impermeability. Also, it is necessary to prevent the yarn constituting the cloth from the cutting terminal formed by the cutting during the production of the airbag from fraying. Furthermore, heat resistance and weather resistance are required for the airbag cloth. Therefore, conventionally, as an airbag cloth, a coated cloth obtained by coating a woven cloth with a silicone rubber coating agent has been used.

[0004] However, the silicone rubber coated cloth has a problem that it is hard to be folded due to the rubber elasticity of the coating layer, so that the workability of folding and storing the airbag in a case is low.

Accordingly, an object of the present invention is to provide an airbag cloth made of a silicone rubber-coated cloth which tends to be easily folded.

[0006]

Means for Solving the Problems The airbag fabric of the present invention is a coated fabric obtained by coating one surface of a synthetic fiber base fabric with a silicone rubber coating agent at a solid content of 20 g / m ² or less. The thickness of the base cloth is 1.
It is not more than 04 times, that is, 1.00 to 1.04 times.

According to the airbag cloth of the present invention, an extremely thin coating film is formed such that the coating amount is low and the thickness after coating is substantially the same as the thickness of the base cloth before coating. Therefore, the conventional coating cloth having a thick coating layer is easily folded, and is soft and inexpensive. Therefore, the folding workability of the airbag is excellent, and the packaging volume can be reduced.

Further, since it is a coated cloth, it has excellent gas impermeability and can prevent yarn fraying due to cutting. Further, since the coating agent is made of silicone rubber, it is superior in environmental resistance such as heat resistance as compared with the case where a chloroprene rubber coating agent is used.

[0009] In the airbag fabric of the present invention, the base fabric is preferably a woven fabric having a cover factor of 1,700 to 2,100. By coating the coating agent with a low basis weight based on such a relatively low-density base cloth, the thickness of the coated cloth is set to 1.
It can be set to 00 to 1.04 times. Further, the coating agent penetrates into the structure of the surface layer of the base fabric to improve the film strength, and the coating film is less likely to be broken when the airbag is inflated and deployed. Moreover, it is excellent in flexibility.

In the airbag fabric of the present invention, the KE
The bending hysteresis measured by S-FB-2 is preferably 0.55 gf · cm / cm or more as an average of bending in two directions perpendicular to each other in the plane of the coated cloth. Thereby, sufficient folding habit is ensured.

In particular, when the base fabric is a woven fabric composed of a warp and a weft, the bending hysteresis should be 0.55 gf · cm / cm or more on average in the bending in the warp direction and the bending in the weft direction. Is preferred.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, matters relating to the implementation of the present invention will be described in detail.

[0013] The airbag fabric of the present invention is provided with a silicone rubber coating on one side of a synthetic fiber base fabric such that the thickness after coating is 1.04 times or less the thickness of the base fabric before coating. It can be obtained by coating the agent with a solid content of 20 g / m ² or less. Specifically, as described in detail below, using a relatively low-density base fabric, a silicone rubber coating agent is applied to one surface of the base fabric in terms of solid content of 5 to 5%.
It can be obtained by coating with a low basis weight of 20 g / m ² .

Examples of the base fabric include woven fabrics such as polyamide fibers such as polyamide 6 and polyamide 66, polyester fibers such as polyethylene terephthalate, and aramid fibers. It is particularly preferable to use plain woven fabrics of polyamide fibers. .

The base cloth has a cover factor of 1,7.
It is preferable to use a woven fabric having a size of 00 to 2,100.
If it is less than 1,700, it is difficult to secure sufficient strength as an airbag, and if it exceeds 2,100, the rigidity of the base fabric becomes large and the flexibility is inferior.

Here, the cover factor is defined by the following equation (1). In the formula, "warp density" is the number of wefts per inch, and "weft density" is the number of wefts per inch.

Warp density × √ (number of denier of warp) + Weft density × √ (number of denier of weft) (1) The fineness of the synthetic fibers constituting the woven fabric is 120 to 63
The denier can be 0 denier, and in this case, the number of background shots is determined according to the fineness so as to satisfy the numerical range of the cover factor.

More specifically, the base fabric is preferably a plain woven fabric of polyamide 66 having a fineness of 420 denier, and the number of punches is preferably 46 / inch.

As the coating agent, an alkenyl group-containing organopolysiloxane such as dimethylpolysiloxane having a dimethylvinylsiloxy group at both ends is mainly used.
Pulverized silica as a reinforcing filler, and an addition reaction vulcanization type silicone rubber coating agent obtained by further blending a curing agent such as an organohydrogenpolysiloxane or a platinum compound are preferable. If necessary, an adhesion improver such as an epoxy group-containing organosilicon compound and a flame retardant aid such as carbon black may be added to the coating agent.
Further, an organic solvent such as toluene may be added so as to easily coat the thin film. In this case, it is preferable to add an organic solvent so that the viscosity at 25 ° C. of the coating agent is 10,000 to 50,000 cs.

The coating agent is applied on one side of the base cloth in an amount of 20 g / m ² or less, preferably 5 to 20 g / m ^{2 in} terms of solid content.
m ² to coat.

By coating the above-mentioned relatively low-density woven fabric with a silicone rubber coating agent with such a low basis weight, as shown in FIG. 1, the unevenness of the woven fabric remains on the coated surface. To the extent, the coating film is formed along the irregularities of the woven fabric, and the thickness after coating becomes substantially the same as the thickness of the woven fabric before coating. That is, the thickness of the coated cloth is 1.00 to 1.04 times the thickness of the base cloth.

Thus, a soft and inexpensive airbag cloth can be obtained. Also, the bending hysteresis by KES-FB-2 becomes 0.55 gf · cm / cm or more,
Therefore, a folding habit is easily formed, and therefore, the work of folding the airbag and the work of storing it in the case become easy. Also, the packaging volume of the airbag is reduced.

The reason why the coating agent is coated on only one side of the base cloth is that the airbag cloth becomes hard when the base cloth is coated on both sides or when the base cloth is immersed in the coating agent. This is because the flexibility is poor.

Here, KES-FB-2 relates to a bending characteristic in a KES (Kawabata Evaluation System) which is a system for measuring basic mechanical characteristics and surface characteristics of a cloth in a low load range. The measurement is performed by the following method. That is, a sample (the length of the sample is, for example, 10 cm) is held by chucks at intervals of 1 cm, and one of the chucks is moved to obtain a curvature K = −2.5 to + 2.5c.
A pure bending having a constant velocity curvature is performed within the range of m ^-1 , and a bending moment M (gf · cm / cm) per unit length of the sample is measured, and the curvature K is 0.5 to 1.5 and −. 0.5 to -1.
Hysteresis width 2 of bending moment M in the range of 5
Find the average value of HB. This is measured by bending the sample in two orthogonal directions, for example, both in the warp direction and in the weft direction, and the average of both is calculated.

The coating method of the coating agent can be performed using various known coating machines such as a knife coater and a comma coater. Further, in order to cure and cure the coating agent, the coating agent may be subjected to heat treatment under an appropriate temperature condition after coating. The coated cloth thus obtained is cut into a predetermined shape and sewn so that the coated surface is on the inner surface side of the airbag, and an airbag is manufactured.

In the airbag cloth of the present invention, JI
Adhesion strength measured according to SK6328.5.3.7 is 1 kgf / cm or more, and JIS L109
6.6.19.1 It is preferred that the bristles measured by the A method be 80 mm or less in both the warp direction and the weft direction. Such adhesion strength and bending resistance can be achieved by coating the above-mentioned relatively low-density woven polyamide fabric with a silicone rubber coating material at a low basis weight.

[0027]

EXAMPLES Next, the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 As shown in Table 1, as a base cloth, a plain woven cloth made of 420 denier polyamide 66 and having a driving count of 46 pieces / inch each (cover factor = 188)
5, thickness = 0.280 mm), and a coating agent of silicone rubber was coated on one surface of the base fabric at a solid content of 15 g / m ² with a knife coater. Here, the coating agent was composed of 23 parts by weight of dimethylpolysiloxane blocked with dimethylvinylsiloxy groups at both ends, fumed silica 7
Parts by weight, 1 part by weight of organohydrogenpolysiloxane, 0.5 part by weight of a platinum-based compound, 1 part by weight of an epoxy group-containing organosilicon compound, 0.5 part by weight of carbon black,
And 70 parts by weight of toluene and an addition reaction vulcanization type silicone rubber coating agent. After coating, the coating was dried in a dryer at 180 ° C. for 7 minutes to obtain an airbag cloth.

[0029]

[Table 1]

Regarding the obtained airbag cloth, the thickness,
The bending resistance, adhesion strength, bending hysteresis, folding habit, and packaging volume were measured. Each measuring method is as follows.

Bending resistance: JIS L1096.69.1.1 Method A Adhesion strength: JIS K6328.5.3.7 Bending hysteresis: Both bending in the warp direction and bending in the weft direction are performed according to KES-FB-2. It measured and averaged. The length of the sample was 10 cm. Folding property: 760 in diameter by cutting airbag cloth
mm circular cloths were obtained, and their peripheral portions were sewn together to form a driver's seat airbag. This airbag,
Fold it into the specified shape, vertical x width is 120mm x 150
mm, and an initial load of 3 kg was applied for 1 hour, and then the state of dispersion when the load was released was visually confirmed. In the table, ○ indicates that the degree of variation is small and the folding habit is good, and X indicates that the degree of variation is large and the folding habit is poor. Packaging volume: The driver's seat airbag was folded into left and right bellows and up and down bellows, and the volume of the folded airbag was measured. In the table, the folding volume of the airbag when the airbag cloth of Comparative Example 1 described later is used is 1
It was shown as an index as 00.

Examples 2 and 3 Using the same base cloth and coating agent as in Example 1, in Example 2, 8 g / m ² of the coating agent was applied to the base cloth, and in Example 3, the coating agent was applied to the base cloth. 19 g / m ² were coated to obtain airbag fabrics of Examples 2 and 3.

[0033]Comparative Examples 1-4 Comparison using the same base cloth and coating agent as in Example 1.
In Example 1, a coating agent was applied to the base cloth at 40 g / m.², Comparison
In Example 2, the base cloth was coated with 25 g / m2 of a coating agent. ², Comparison
In Example 3, a coating agent was applied to the base cloth at 21 g / m 2.²Each
Then, the fabrics for airbags of Comparative Examples 1 to 3 were obtained.

Comparative Example 4 was made of polyamide 66 having 420 denier, and the number of shots was 54
Plain woven fabric per book / inch (cover factor = 223)
1, thickness = 0.322 mm) was used as an airbag cloth without being coated with a coating agent.

As shown in Table 1, the thicknesses of the airbag fabrics of Examples 1 to 3 were substantially the same as the thickness of the base fabric before coating, that is, the thickness of the coated fabric relative to the base fabric thickness (a) before coating. The thickness ratio (b) / (a), which is the thickness (b), was 1.00, 1.00, and 1.03, respectively, and had an extremely thin coating film. For this reason, the bending hysteresis was as large as 0.55 gf · cm / cm or more, the folding habit was easily formed, and the created airbag was easily folded. Further, the packaging volume of the airbag was small due to the small thickness. Further, the bending resistance was 80 mm or less in both processes, and the flexibility was excellent. Also, the adhesive strength was excellent. In addition, since it is a coated cloth, the gas permeability is 0 and the gas permeability is excellent,
There was no thread fraying caused by cutting when making the airbag.

On the other hand, in the airbag fabrics of Comparative Examples 1 and 2, the thickness ratio (b) / (a) was 1.08, respectively.
1.05, and because the coat was thicker,
The bending hysteresis was as small as 0.41 and 0.48, respectively. For this reason, it is difficult to have a folding habit, and it is difficult to fold the created airbag. Further, the packaging volume of the airbag was larger than that of Example 1.

The airbag fabric of Comparative Example 3 had a relatively small thickness ratio (b) / (a) of 1.04, but the basis weight of the coating agent was more than 20 g / m ^2. Has a bending hysteresis of 0.53 gf · cm / cm
Therefore, the folding habit was not sufficient. Further, the packaging volume of the airbag was larger than that of Example 1.

Although the airbag fabric of Comparative Example 4 had a large bending hysteresis of 0.99 and was easily folded, the thickness of the airbag fabric was high because the fiber density was increased to reduce the air permeability. As a result, the packaging volume of the airbag was larger than that of Example 1, and the flexibility was poor. Further, since the airbag fabric of Comparative Example 4 is a non-coated fabric, it is inferior in gas non-permeability,
Moreover, yarn fraying due to cutting was apt to occur.

[0039]

As described above, in the airbag fabric of the present invention, the coating amount is low and the thickness after coating is substantially the same as the thickness of the base cloth before coating. Since a thin coating film is formed, a conventional coating cloth having a thick coating layer is easily folded and is soft and inexpensive. Therefore, the workability of folding and storing the airbag in the case is excellent, and the packaging volume can be reduced.

Further, since it is a coated cloth, it has excellent gas impermeability and can prevent the yarn from being frayed by cutting. Further, since the coating agent is made of silicone rubber, it has excellent heat resistance and weather resistance.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of an airbag cloth according to an embodiment of the present invention.

Continued on the front page F term (reference) 3D054 AA02 AA03 AA13 AA14 CC26 CC27 CC45 FF01 FF02 FF03 FF17 FF18 FF20 4L033 AA08 AB04 AB05 AC15 BA96 CA59 CA68 CA70 DA06 4L048 AA24 AB07 BA01 BA02 CA15 DA25

Claims (6)

[Claims] 1. A coated cloth comprising a base cloth made of synthetic fiber and a silicone rubber coating agent coated on one side at a solid content of 20 g / m ² or less, wherein the thickness of the base cloth is 1. A cloth for an airbag, which is not more than 04 times. 2. A coated cloth comprising a synthetic fiber base cloth coated on one side with a silicone rubber coating agent at a solid content of 20 g / m ² or less, wherein the thickness of the base cloth is 1. An airbag cloth with excellent folding habit of not more than 04 times. 3. The method according to claim 1, wherein the base cloth has a cover factor of 1,700.
The airbag fabric according to claim 1, wherein the fabric is a woven fabric of ~ 2,100. 4. The base fabric is made of polyamide 66 having a fineness of 420 deniers.
The airbag fabric according to claim 3, wherein the fabric is an inch woven fabric. 5. The bending hysteresis of the coated cloth measured by KES-FB-2 is 0.55 gf · c on average of bending in two directions perpendicular to each other in the plane of the coated cloth.
The airbag fabric according to claim 1, wherein the airbag fabric has a m / cm or more. 6. The base fabric is a woven fabric, and the bending hysteresis of the coated fabric measured by KES-FB-2 is 0.55 gf · cm on average of the bending in the warp direction and the bending in the weft direction of the woven fabric. 2 / cm or more.