JP3209334B2 - Non-coated airbag fabric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fabric for an airbag, which is one of safety devices for automobiles, and more particularly, to a compact and low air permeability while maintaining necessary mechanical properties. An object of the present invention is to provide a nonwoven fabric for a non-coated airbag, which is possible and economical.

[0002]

2. Description of the Related Art In recent years, airbags, which are rapidly increasing in their mounting rate as one of automobile safety parts, detect high impact and high-pressure gas from an inflator in the event of an automobile collision. The gas is used to rapidly deploy the airbag to prevent and protect the driver or passenger's body, especially the head, from jumping out in the direction of the collision and colliding with the steering wheel, windshield, door glass, etc. Conventionally, airbags have a coating base fabric coated with synthetic rubber such as chloroprene, chlorsulfonated olefin, silicone, etc., because they have high heat resistance, air barrier properties (low air permeability), and high flame retardancy. Had been used.

However, these coated base fabrics have a high base fabric weight and are not satisfactory in flexibility.
Since the production cost is high and it is not recyclable,
There were many problems in using it as a base fabric for airbags.

[0004] Although the above-mentioned disadvantages have been considerably improved in silicone-coated base fabrics still used in some cases, they are still not satisfactory.

Therefore, recently, non-coated airbags using a non-coated airbag base fabric which is not coated have become mainstream, and the following proposals have been made to reduce the weight, provide good storage properties, and reduce air permeability. Has been made.

1) A method of obtaining a lightweight, low-permeability base fabric by shrinking or calendering after weaving a high-density woven fabric (Japanese Patent Laid-Open No. 1-127552). 2) A method capable of obtaining a light-weight, low-permeability base cloth of 0.5 cc / cm2 / s or less at a differential pressure of 124 Pa by performing double-sided calendering (JP-A-4-2835). 3) A method of subjecting a woven fabric to a chemical shrinkage treatment to swell the threads constituting the fabric to obtain a low-permeability base fabric (Japanese Patent Application Laid-Open No. 6-41844). 4) Thermoplastic synthetic fiber A having single yarn fineness of 1.5d to 7.0d
And a method of mixing 0.2 d to 1.5 d of thermoplastic synthetic fiber B (JP-A-8-325888).

However, with the demand for lighter and more compact vehicles, even non-coated airbags are required to be lighter and more compact. However, they have a low weight, are excellent in compactness, and have low air permeability. Producing an economical airbag fabric is, for example, even if the air permeability is low under a low differential pressure condition, the air permeability becomes high as a result of a change in pore size at a high differential pressure.
This cannot be achieved by the conventional methods 1) to 4).

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fabric for an airbag which is low in weight, excellent in compactness, low in air permeability and excellent in economy.

[0009]

Means for Solving the Problems The present inventors have found that by controlling the pore distribution PD of pores formed by the fibers constituting the woven fabric, a woven fabric for a non-coated airbag having a low basis weight and a low air permeability can be obtained. We have found and completed the present invention.

The present invention has the following configuration in order to solve the problems that cannot be achieved by the above-mentioned conventional method.
That is, the airbag fabric of the present invention is made of a thermoplastic fiber fabric, and in the pores formed by the constituent fibers, the pore size distribution of pores, that is, the pore distribution is set to 2.0 or less, and the difference of 20 kPa is obtained. Air permeability is 2.5 L / cm2 by pressure
/ Min or less.

The pore distribution is defined by the following equation (Equation 2).

PD = (FDmax−FDmin) / FDave Here, FDmax: maximum pore size (μm) FDmin: minimum pore size (μm) FDave: average flow pore size (μm)

Specifically, the airbag woven fabric of the present invention is characterized in that the thickness of a single fiber and the woven density with respect to the shrinkage ratio and the thickness of a multifilament of a fabric composed of thermoplastic fibers are adjusted, and It is to control the pore distribution by heating and performing appropriate shrinkage processing. The weaving density is preferably adjusted by adjusting the density of the greige and the shrinkage ratio of the weaving machine under weaving conditions. The pore distribution is
More preferably, it is 1.9 or less, and the air permeability is 1.9.
It is more preferable that the number is 4 or less as a fabric for a non-coated airbag.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoplastic fiber used in the present invention must have a raw yarn boiling water shrinkage of 5 to 15%. If the raw yarn boiling water shrinkage is less than 5%, the desired low air permeability cannot be obtained, and if it is more than 15%, the thickness of the woven fabric after shrinkage becomes large and the compactness is impaired, which is not preferable. The value of the raw yarn boiling water shrinkage is preferably about 5 to 15%, and more preferably 8 to 12%.

The heat treatment temperature for performing the shrinkage treatment in the present invention is not particularly limited, and is usually 100 to 100.
Performed at 200 ° C. Preferably, treatment at 160 ° C. or lower is suitable for obtaining low air permeability. The apparatus for performing the shrinking treatment is not particularly limited, such as a heat setter, a boiling water bath, or the like.
Use a device capable of about 5%. In the present invention, it is necessary to adjust the distribution of pore sizes made of the fibers constituting the woven fabric, and therefore, it is particularly preferable to use equipment capable of coping with such adjustment. By controlling the heat treatment temperature and limiting the overfeed rate, the pore size can be adjusted and made uniform, and a nonwoven fabric for a non-coated airbag having a low basis weight and a low air permeability can be manufactured.

The pore distribution value of the present invention is a numerical value indicating the distribution of pores made of the fibers constituting the fabric. As shown in (Equation 2), the difference between the maximum pore size and the minimum pore size is calculated as the average flow rate. It is a value obtained by dividing by the pore diameter at the time (average flow pore size). The pore distribution value PD of the present invention is:
It is necessary to be 0 or less, preferably 1.5 or less, and more preferably 1.3 or less. If the pore distribution value is larger than 2.0, a fabric with low air permeability cannot be obtained, which is not preferable.

The weaving method is not particularly limited, but plain weaving is preferable in consideration of the uniformity of the properties of the base fabric. The weaving machines used for weaving include an air jet room, a rapier room, and a water jet room. It is exemplified and not particularly limited.

The thermoplastic fibers constituting the airbag in the present invention include nylon-6, nylon-6,6, and nylon-6.
Examples thereof include aliphatic polyamide fibers such as nylon-4, 6, and nylon-12, and polyester fibers such as polyethylene terephthalate and polybutylene terephthalate.
There is no particular limitation. However, considering economics and impact resistance, nylon-6,6, nylon-4,6,
The use of polyamide fibers such as nylon-6 is particularly preferred. In addition, there is no problem even if these synthetic fibers contain or are provided with various additives in order to improve the processability in the raw yarn manufacturing process and the post-processing process. Examples of such additives include antioxidants, heat stabilizers, leveling agents, antistatic agents, flame retardants, and the like.

The total fineness and single yarn fineness of the used yarn are preferably 100 to 700 d and the single yarn fineness is 8 d or less, more preferably the total fineness of the used yarn is 150 to 420 d. The single yarn fineness 4d is preferably as follows.

When the total fineness is less than 100 d, the tensile strength and tear strength of the fabric are insufficient, and when it is more than 700 d, the flexibility of the fabric is impaired, which is disadvantageous for the storage property, and the size of the airbag is reduced. Inability to respond to requests.

If the single-fiber fineness exceeds 8 d, this also impairs the flexibility of the woven fabric, which is disadvantageous for storage.

In the present invention, the air permeability is 20 kPa differential pressure.
In this case, it is 2.5 L / cm2 / min or less, preferably 1.5 L / cm2 / min or less, and more preferably 1.0 L / cm2 / min or less. If the air permeability is larger than 2.5 L / cm2 / min, the expandability of a non-coated airbag is not preferable.

The raw yarn is preferably substantially non-twisted or sweet-twisted, and more preferably non-twisted. This is because, when attempting to obtain a low-permeability woven fabric using a low single-filament yarn, twisting impairs the spread of the single yarn, making it difficult to reduce the air permeability.

The difference in the weaving shrinkage ratio between the warp and the weft of the woven fabric of the present invention is preferably 4% or less. When it is more than 4%, the maximum pore size in the pore distribution becomes large and it is often difficult to obtain a woven fabric with low air permeability. The weave shrinkage ratio of the present invention is preferably 2 to 6% in order to reduce the pore distribution. Preferred, but not limiting.

[0024]

Next, the present invention will be described in more detail by way of examples. The physical properties in the examples were measured by the following methods. Basis weight: JIS L1096 6.4.2 Weave density: JIS L1096 6.6 Air permeability: Measured by an air flow meter manufactured by OEM System Co., Ltd. Bend softness: JIS L1096 6.19.1. Method A (4
5 ° cantilever method) Boiling water shrinkage: JIS L1013 Hot water shrinkage B method 1
00 ° C Pore size (FDmax, FDmin, FDave):
COULTER ELECTRONICS LIMIT
Measured using ED COULTER POROMETER.

Example 1 Non-twisted 420d / 14 warp
4f (single yarn fineness 2.9d), boiling water shrinkage = 9.5%, and non-twisted 420d / 144f (single yarn fineness 2.9d), boiling water shrinkage = 9.5% are used for the weft. After weaving a plain woven material in a water jet loom, the overfeed rate is adjusted with boiling water, shrinkage processing is performed, and then drying set finishing is performed at 140 ° C. to adjust the pore distribution value to 1.0, and to perform non-coating. A fabric for an airbag was obtained.
Table 1 shows the physical property evaluation results of this non-coated airbag fabric.

Example 2 Non-twisted 315 d / 10 warp
8f (single yarn fineness 2.9d) boiling water shrinkage ratio = 9.5% is used, and the weft is untwisted 315d / 108f (single yarn fineness 2.9).
d) After weaving a plain weave in a water jet loom using a boiling water shrinkage rate of 9.5%, the overfeed rate is adjusted with boiling water, shrinkage processing is performed, and then drying set finishing is performed at 130 ° C. to obtain pores. The distribution value was adjusted to 1.2 to obtain a non-coated airbag fabric. Table 1 shows the physical property evaluation results of this non-coated airbag fabric.

Example 3 Non-twisted 315d / 72 warp
f (single yarn fineness: 4.4d) Boiling water shrinkage ratio = 10.5%, and 315d / 72f (single yarn fineness: 4.4
d), after weaving a plain woven material in a water jet loom using a boiling water shrinkage ratio of 10.5%, shrinking processing is performed by adjusting the overfeed ratio with boiling water, and then dry set at 140 ° C. to finish the pores. The distribution value was adjusted to 1.8 to obtain a non-coated airbag fabric. Table 1 shows the physical property evaluation results of this non-coated airbag fabric.

(Comparative Example 1) Non-twisted 315d / 14 to warp
Using 4f (single yarn fineness 19d) boiling water shrinkage = 9.5%, the weft has no twist, 420d / 144f (single yarn fineness 2.9).
d), after weaving a plain woven material in a water jet loom using a boiling water shrinkage rate of 9.5%, the overfeed rate is adjusted with boiling water, shrinkage processing is performed, and then drying set finishing is performed at 160 ° C. to obtain pores. The distribution value was adjusted to 2.1 to obtain a non-coated airbag fabric. Table 1 shows the physical property evaluation results of this non-coated airbag fabric.

(Comparative Example 2) Non-twisted 315d / 72 warp
f (single yarn fineness 4.4d), using a boiling water shrinkage rate of 10.5%, and weft-free twisting 315d / 72f (single yarn fineness 4.4)
d), after weaving a plain woven material in a water jet loom using a boiling water shrinkage ratio of 10.5, the overfeed ratio is adjusted with boiling water, shrinkage processing is performed, and then drying set finishing is performed at 180 ° C. to obtain pore distribution. The value was adjusted to 2.4 to obtain a non-coated airbag fabric. Table 1 shows the physical property evaluation results of this non-coated airbag fabric.

(Comparative Example 3) Non-twisted 315 d / 10 warp
Using 8f (single yarn fineness 2.9d) boiling water shrinkage = 9.5%, non-twisted 315d / 108f on weft, boiling water shrinkage =
After weaving a plain woven material in a water jet loom using 9.5%, the overfeed rate is adjusted with boiling water, shrinkage processing is performed, and then dry set finishing is performed at 170 ° C. to obtain a pore distribution value of 2.2. Thus, a fabric for a non-coated airbag was obtained. Table 1 shows the physical property evaluation results of this non-coated airbag fabric.

[0031]

[Table 1] As is clear from Table 1, the fabric of the present invention has a low basis weight,
It can be seen that the fabric has low air permeability.

[0032]

According to the present invention, there is provided an economically excellent airbag fabric which is flexible and has low air permeability while maintaining the mechanical properties required for an airbag fabric and has a low weight per unit area. can do.

Claims (3)

(57) [Claims] 1. A woven fabric formed of thermoplastic fibers, wherein a pore distribution value (PD) of the pores formed by the thermoplastic fibers is 2.0 or less. And air permeability at a differential pressure of 20 kPa is 2.5 (L / cm
2 / min) or less. PD = (FDmax−FDmin) / FDave FDmax: Maximum pore size (μm) FDmin: Minimum pore size (μm) FDave: Average flow pore size (μm) 2. The woven fabric for a non-coated airbag according to claim 1, wherein the difference in the weaving shrinkage ratio between the warp and the weft is 4% or less. 3. The woven fabric for a non-coated airbag according to claim 1, wherein the thermoplastic fiber is a polyamide fiber.