JP2003183945A - High-density ground fabric for air bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-density woven fabric for an air bag, having excellent impact resistance, low air-permeability, and storing performance by decreasing a difference of bending resistance between the longitudinal and transverse directions, without problems on quality of the ground fabric, such as ground fabric strength and burst pressure. <P>SOLUTION: This high-density woven fabric for the air bag is woven by using synthetic fiber filament yarns as the warp and/or the weft, wherein the warp or the weft has a flat cross section. A flatness of the warp is greater than that of the weft, and therefore a ratio of the flatness of the warp to that of the weft is not less than 1.3. Further, the ground fabric is coated with a resin, so that the low air-permeability of the fabric is achieved. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density fabric for shock absorbing airbags for ensuring safety. More specifically, the purpose is to reduce the rigidity of the woven base fabric in the longitudinal / latitude directions to improve the storability and at the same time reduce the air permeability. The present invention relates to a high-density woven fabric for airbags that absorbs more of the above and reduces bruise on the face.

[0002]

2. Description of the Related Art In recent years, an airbag system has been widely used from the viewpoint of ensuring safety of passengers in an automobile.
The sensor of the vehicle catches the airbag due to collision or impact such as accident, and the airbag is rapidly deployed by the high temperature and high pressure gas from the gas generator to restrain the occupant and reduce the shock of the occupant. In order to remove the gas generated in the airbag, it is common to use a method of providing pores on the opposite face side or reducing the weave density, but it is also used for airbag base fabric. By reducing the thickness (fineness) of the thread, the bending resistance of the base cloth is reduced, and a base cloth that is gentle on the face has been developed. In the weaving process of such a base fabric, the flying tension (unwinding tension) of the weft is higher than the weaving tension of the warp, and therefore the weave of the weft that expands the base fabric structure is smaller than that of the warp. . Further, when the weft yarn is disentangled and the yarn characteristics are examined, the weft yarn has a larger modulus and the crimp ratio is smaller than the warp yarn. As a result,
The flexibility of the base cloth varies greatly in the width (weft) direction and the length (warp) direction.

Japanese Unexamined Patent Publication (Kokai) No. 9-78391 discloses to provide a high-density woven fabric for airbags which has a low bending resistance and is excellent in impact resistance and low air permeability. It is not described that the difference in bending resistance between the two is reduced to further improve the storability.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to improve the above-mentioned problems of the prior art so that there are no problems with the quality of the base cloth such as strength of the base cloth, burst pressure, etc. (EN) It is intended to provide a high-density woven fabric for an airbag, which has a small difference in stiffness and softness, and is excellent in impact resistance, low air permeability, and storability.

[0005]

Means for solving the above problems, that is, a high-density fabric for airbags of the present invention is a high-density fabric composed of warp yarns and weft yarns made of synthetic filament yarns, Characterized in that the warp and weft are flat in cross section, the warp's flatness is greater than the weft's flatness, and the ratio of the warp's flatness to the weft's flatness: warp / weft is 1.3 or more Is. Further, this base cloth is coated with a resin to further improve low air permeability.

In the high-density woven fabric of the present invention, the fineness of the warp and the weft is preferably 155 to 550 dtex. In addition, the warp and weft strengths are 5.7 CN / dtex.
The above is preferable. Further, it is preferable that the synthetic filament yarn is made of polyamide fiber.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The synthetic filament yarn referred to in the present invention is a yarn made of a thermoplastic resin, and may be any yarn as long as there is no problem in the quality of the base fabric (base fabric strength, burst pressure, etc.) when it is formed into an airbag. Examples thereof include threads made of nylon 6, nylon 66, nylon 12, nylon 46, polyamide such as a copolymer of nylon 6 and nylon 66, and polyester. These yarns may contain an antioxidant in order to improve thermal stability.
Further, it may contain a thickener, a lubricant and the like for improving productivity.

The greatest feature of the present invention is that the single yarn cross section of the warp yarn and the weft yarn constituting the high density woven fabric is not an ordinary round cross section but a deformed cross section having a specific flatness.
Furthermore, the warp and weft are flat in cross section, the warp's flatness is larger than the weft's flatness, and the ratio of the warp's flatness to the weft's flatness: warp / weft is 1.3 or more. To do. Further, this base cloth is coated with a resin to further improve low air permeability.

When a modified cross-section yarn having a flatness of a certain level or more (hereinafter, simply referred to as a flat yarn) is used, when a woven fabric is formed, the long diameter of the single yarn cross-section is arranged parallel to the plane of the woven fabric. Become. When the base fabric is formed by changing the flatness of the warp and the weft as in the present invention, the major axes of the warp and weft yarn cross sections are arranged in parallel, and a base fabric that is even thinner than the conventional one can be obtained. It maintains the mechanical properties of. Surprisingly, the gap per unit surface area is reduced in the thickness direction of the fabric, and the ventilation rate is suppressed as compared with the case where the circular cross section of the same fineness is used and the weave density is equal. . In addition, if it is attempted to design the ventilation amount to be equal, it is possible to reduce the total fineness, and it is possible to obtain a thin and lightweight base fabric.

The flatness of the single yarn cross section in the present invention is defined by the ratio of the major axis to the minor axis when the single thread cross sectional shape is approximated to an ellipse. The cross section does not need to be strictly elliptical, and may have a projection or a depression in a part within a range that does not affect the flatness of the whole. Even in such a case, the flatness may be calculated by approximating an ellipse that does not impair the overall outer shape.

In order to obtain the effect of the present invention, the flatness of the warp is 3.5 or less, more preferably 2.5 or less, and the flatness of the weft is 3.0 or less, more preferably 2.
It must be 0 or less. At the same time, the ratio of the flatness of the warp to the flatness of the weft: warp / weft is 1.3 or more. This ratio is 1.
If it is less than 3, even if it is a flat cross section, the single yarn cross section tends to be randomly positioned when it is made into a woven fabric, and the voids in the fabric thickness direction become large. In addition, the probability that the major axis and the minor axis are oriented in the same direction is reduced. Therefore, the effect of reducing the ventilation amount and reducing the weight of the present invention cannot be obtained.

Further, when the flatness ratio of the warp yarn and the weft yarn is 1.3 or more as in the present invention, the flexibility is further maintained and the bending resistance is increased. Even more surprisingly, the bending resistances in the warp and weft directions are almost the same, and the difference is 10% or less in the ratio of warp / latitude, and the storability is further improved.

FIG. 1 shows an example of a typical modified cross section in the present invention. Of course, these are representative examples, and the present invention is not limited thereto. In FIG. 1, a is the major axis, b is the minor axis, and the flatness is calculated by a / b.

The resin to be applied to the high density woven fabric of the present invention is 1 to 70 g / m ^2, preferably 1 to 30 without diluting the addition type silicone rubber coating agent with a solvent.
It is formed by applying a coating amount of g / m ² . As long as it is made of a base cloth made of filament yarn having a modified cross section with a fineness of 150 to 500 d, it can be a thin, lightweight, easy to fold, and excellent in storability. Also, since the surface area is increased by making the filament yarn a modified cross section, the coating amount is also 1 to 30 g /
Gas leakage can be prevented with a thin coating film of m ² . Therefore, the weight can be reduced as compared with the conventional coat type. The surface smoothness is excellent, and the airbag can be made more compact.

Further, in the present invention, the addition type silicone rubber coating agent is preferable as the coating agent, and heat vulcanizing silicone rubber, room temperature vulcanizing silicone rubber, water-soluble emulsion silicone rubber and the like are also effective. Conventionally known chloroprene-based coating agents and urethane-based coating agents may be used, but silicone-based coating agents are preferable, and silicone-based coating materials are particularly preferable in the case of base fabric made of flat yarn. Due to the surface tension, the speed of bleeding over the entire base fabric after application is high.

The coating agent preferably has a viscosity of 1 to 200 Pa.s, preferably 1 to 1
A viscosity of 00 Pa · s is good. By coating with a knife coater, the coating amount is preferably 1 to 30 g / m ² and thin,
In addition, a uniform coating film can be easily formed.

As a method for applying the resin liquid to the surface of the obtained base cloth, there are gravure coating and printing with a resin having the above-mentioned characteristics, and dipping is a method for applying the resin even to the inside of the cloth. However, the means is not limited, but it is determined so that the fabric laminated or provided with the resin has an air permeability of 1.2 cm ³ / sec / cm ² or less.

The fineness of the warp and the weft constituting the high-density fabric of the present invention is substantially equal to each other, and the fineness of the single yarn constituting the weft is smaller than the fineness of the single yarn constituting the warp. Here, the fact that the fineness of the warp and the weft is “substantially equal to each other” means that the fineness of one of the warp and the weft is in the range of −3% to + 3% with reference to the fineness of the other. As described above, by making the finenesses of the warp threads and the weft threads substantially equal to each other, variations in air permeability and strength of the base cloth are reduced, and the quality of the base cloth is stabilized. Further, by making the fineness of the single yarn forming the weft smaller than that of the single yarn forming the warp, the difference in the bending resistance between the width direction and the length direction of the base fabric is reduced, and the effect of lowering air permeability is obtained. By making the above-mentioned cross-section different and applying a resin, it is possible to further reduce the air permeability. Generally, the fineness of the single yarn constituting the weft is 1.1 dte with respect to the fineness of the single yarn constituting the warp.
When the difference is at least x, the effect on the bending resistance and breathability of the base cloth is produced, but if the difference is 1.1 dtex or less, bending resistance cannot be expected. It is preferable that there is a difference of 2.2 dtex or more.

In the present invention, the fineness of the warp and the weft is 1
It is preferably set to 55 to 550 dtex. Fineness is 1
When it is less than 55 dtex, the weight of the base fabric is reduced, but the burst pressure (burst pressure) at the time of deployment becomes low, which causes a problem in ensuring the safety of passengers, which is not preferable. On the other hand, if it exceeds 550 dtex, the strength of the base cloth is improved, but the cost performance is deteriorated due to the lightweight and compactness of the airbag, the higher functionality, and the increase in the basis weight of the base cloth, which is not preferable. More preferable warp and weft fineness is 2
It is 75-495 dtex.

In the present invention, the strength of the warp and the weft is preferably 5.7 CN / dtex or more. Strength is 5.
If it is less than 7 CN / dtex, the burst pressure (burst pressure) at the time of deployment becomes low, which causes a problem in ensuring the safety of the occupant, which is not preferable.

Further, in the present invention, when the polyamide fiber is adopted as the synthetic filament yarn, the following characteristics are brought out as compared with the polyester, which is preferable. That is,
1. Large amount of heat retention 2. High strength and elongation of raw yarn and excellent drawability (good post-processability and base fabric quality) 3.
Low specific gravity (light weight and compactness), and 4. low modulus (softening). However, conventional polyester fibers were also relatively disadvantageous in terms of thermal properties, but in the future, the development of low-temperature inflators will allow them to be installed as airbags.

When polyamide fibers are used, it is preferable to use those which satisfy the following characteristics, in order to achieve the object of the present invention. That is: Relative viscosity: ≧ 2.
5, fineness: ≧ 155 dtex, strength: ≧ 5.7 CN / d
tex, breaking elongation: ≤30%, hot water shrinkage: ≥5%, and by setting the strength of the polyamide fiber to 5.7 CN / dtex or more, the strength of the base fabric can be improved. Then, in order to obtain a yarn having a yarn strength of 5.7 CN / dtex, a relative viscosity of 2.5 or more is required. A more preferable strength is 6.5 CN / dtex or more, and a more preferable relative viscosity is 3.0 or more. The fineness of the polyamide fiber is preferably 155 dtex or more, more preferably 275 dtex or more. When it is 155 dtex or less, the burst pressure (burst pressure) at the time of deployment when formed into an airbag becomes low, which causes a problem from the viewpoint of safety, which is not preferable. Further, the cutting elongation is preferably 30% or less from the viewpoint of improving the strength of the base fabric, and more preferably 25% or less. The hot water shrinkage is preferably 5% or more from the viewpoint of lowering the air permeability of the base fabric, and more preferably 8.0% or more.

The high-density fabric for airbags of the present invention is a coated base fabric, and generally has a warp and weft density of 40 or more per inch, a basis weight of 1 to 70 g / m ² , and a thickness of 0.15. ~0.40mm, breathable is 1.2cm ³ / se
It is c / cm ² or less. Breathability is preferably 1.2 cm ³ / sec / cm with a ventilation rate of 1.27 cm pressure drop of the fabric
² or less, more preferably 0.7 cm ³ / sec / cm ² or less. Here, the ventilation amount of the cloth is JIS-L.
It is the value measured according to the 1096-6.27A method. That is, the amount of air passing through the test piece under a pressure of 1.27 cm of water was determined. The air flow rate is 1.
When it exceeds ² cm ³ / sec / cm ² , it is not preferable because the highly reliable instantaneous deployability as an airbag base fabric is reduced.

The high-density woven fabric for airbags of the present invention can be used as a high-density woven fabric of a transparent cloth and a non-permeable cloth.

EXAMPLES Next, the present invention will be described more specifically by way of examples.
The performance evaluations of the yarns and the woven fabrics in the examples were performed as follows.

(Aeration amount) JIS-L1096-6.27
It measured according to the A method.

(Yarn Strength) JIS L1017 (7-5)
Was carried out according to.

(Woven density) JIS L1096 (6.6)
Was carried out according to.

(Tensile Strength and Tensile Elongation) JIS L1
096 6.12-1A method.

(Bending flexibility) JIS L1096 6.19.
It was performed according to the 1A method (45 ° cantilever method).

(Basis weight) It was carried out according to JIS L1096 6.4.2.

[Example 1] A polyamide (NY-66) chip having a relative viscosity of 3.0 was spun by a melt spinning method using a flat yarn nozzle having 120 nozzle holes and 72 nozzles, respectively. The spinning temperature is 290 ° C, and a heating cylinder is provided just under the nozzle to obtain a low birefringence yarn (280 ° C),
An oil agent was applied by a roller, and the oil was guided to the first roller at a spinning speed of 600 m / min, stretched and wound. Further, in order to improve the post-processing passability, the degree of entanglement by air is applied before winding, and 321 dtex / 120 f and 321 dtex /
Each of the 72f yarns was produced. The yarn characteristic obtained is 3
About 21dtex / 120f, yarn strength is 7.4CN
/ Dtex, cutting elongation 20%, entanglement degree 18 / m, flatness 1.4, and for 321 dtex / 72f,
The yarn strength was 7.5 CN / dtex, the breaking elongation was 20%, the degree of entanglement was 25 pcs / m, and the flatness was 1.5. The above-mentioned 321 dtex / 72f yarn is used as a warp, and 321 dte is used as a weft yarn.
Each of the x / 120f yarns was used and weaved with a plain weave in a water jet loom with a weft density of 46 yarns / inch and a warp density of 46 yarns / inch, and scouring was carried out. 15 g / m ² of silicone resin was applied to this base cloth.

[Comparative Example 1] The same condition treatment as in Example 1 was carried out except that silicon was not applied.

Example 2 A polyamide (NY-66) chip having a relative viscosity of 3.0 was spun by a melt spinning method using flat yarn nozzles having 36 and 72 nozzle holes. The spinning temperature is 290 ° C., a heating cylinder is provided just below the nozzle to obtain a low birefringence yarn (280 ° C.), an oil agent is applied by a roller, the spinning speed is 600 m / min, the yarn is drawn to the first roller and drawn and wound. I took it. Further, in order to improve the post-processability, the degree of entanglement by air is given before winding, and 231 dtex / 36f and 231 dtex / 7 are provided.
Each of the 2f yarns was produced. The yarn characteristic obtained is 23
For 1 dtex / 36f, yarn strength is 7.4CN / d
tex, cutting elongation 20%, entanglement degree 18 pcs / m, flatness 1.4, and 231 dtex / 36f, yarn strength 7.5CN / dtex, cutting elongation 20%, entanglement degree 2
It was 5 pcs / m and the flatness was 1.5. 2 as the warp
31dtex / 36f yarn, 231dtex as weft yarn
/ 72f yarns were respectively used and weaved in plain weave in a water jet loom with a weft density of 46 yarns / inch and a warp density of 46 yarns / inch, and scouring was carried out. Silicone resin was applied to the base cloth at 25 g / m ² .

Comparative Example 2 The same processing conditions as in Example 2 were used except that the flatness was changed.

Example 3 A polyamide (NY-66) chip having a relative viscosity of 3.0 was spun by a melt spinning method using flat nozzles having 120 nozzle holes and 68 nozzles, respectively. The spinning temperature is 290 ° C, and a heating cylinder is installed just below the nozzle to obtain a low birefringence yarn (280
C.), an oil agent was applied by a roller, the fiber was guided to the first roller at a spinning speed of 600 m / min, and stretched and wound. Also, in order to improve the post-processing passability, the degree of entanglement by air is given before winding, and 462 dtex / 120 f, and 462 dt
The ex / 68f yarns were produced. The obtained yarn characteristics are such that, for 462 dtex / 120f, the yarn strength is 7.
4CN / dtex, cutting elongation 20%, entanglement degree 18 /
m, flatness 1.4, 462 dtex / 68f, yarn strength 7.4CN / dtex, cutting elongation 20.
%, The degree of confounding was 25 / m, and the flatness was 1.5. 462 dtex / 68f yarn as warp, 4 as weft
62dtex / 120f yarns were respectively used, weaving was carried out in plain weave in a water jet loom with a weft density of 46 yarns / inch and a warp density of 46 yarns / inch, and scouring was carried out. 20 g / m ² of silicone resin was applied to this base cloth.

[Comparative Example 3] Except that the flatness ratio is changed,
It processed on the same conditions as Example 3. The results are shown in Table 1.

[0038]

[Table 1]

From Table 1, it can be seen from Example 1 and Comparative Example 1 that the high density woven fabrics have a small difference in warp / latitude bending resistance when the flatness ratio: warp / latitude is 1.3 or more. It turns out that it is excellent in storability. In Example 2 and Comparative Example 2 as well, if the warp / weft single yarn fineness difference and the flatness ratio: warp / weft of 1.3 or more, the difference in warp / weft bending resistance is small, and storage It can be seen that it has excellent properties. Furthermore, the difference in flatness between Example 3 and Comparative Example 3 appears as the difference in bending resistance.

[0040]

As described above, the high-density fabric of the present invention has
It has low bending resistance and excellent air quality, such as low air permeability, and is very suitable as a high-density fabric for airbags.

[Brief description of drawings]

FIG. 1 Example of cross section of weft and warp

[Explanation of symbols]

a major axis b Short diameter

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Claims (7)

[Claims] 1. A high-density fabric coated with a resin, which is composed of synthetic warp yarns and weft yarns, wherein the warp yarns and the weft yarns are flat yarns, and the flatness of the warp yarns is larger than that of the weft yarns. A high-density fabric for airbags that has excellent storage capacity. 2. The high-density woven fabric for an airbag according to claim 1, wherein the ratio of the flatness of the warp to the flatness of the weft: warp / weft is 1.3 or more. 3. The high-density woven fabric for airbag according to claim 1, wherein the ratio of warp / weft bending resistance is 10% or less. 4. The high-density fabric for airbag according to claim 1, wherein the coating amount of the resin is 1 to 70 g / m ² . 5. The fineness of the warp and weft yarns is 155 to 550.
The high-density fabric for airbag according to any one of claims 1 to 4, which is dtex. 6. The strength of the warp and the weft is 5.7 CN / dte.
The high-density fabric for airbags according to any one of claims 1 to 5, which is x or more. 7. The high-density fabric for an airbag according to claim 1, wherein the synthetic filament yarn is made of polyamide fiber.