JP2003293241A - Base fabric for air bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-coat base fabric for air bags having low air permeability and a storage property without carrying out coating processing. <P>SOLUTION: In the non-coat base fabric, a flat cross section fiber having a flat cross section in which a flatness ratio (a/b) obtained from long axial length (a) and short axial length (b) of a single yarn is 1.5-8 is used and a cover factor is 1,600-2,400 and a relationship between total fineness D1 (dtex) of warp and a yarn width W1 (mm) of a woven fabric and a relationship between total fineness D2 (dtex) of weft and yarn width W2 (mm) of the woven fabric each satisfy the following formulas: D1/W1=770-1,000 and D2/W2=770-1,000. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a base fabric for a non-coated airbag. More specifically, by using a flat cross-section fiber in which the cross-sectional shape of a single yarn is a flat cross section, by controlling the total fineness of the warp and weft and the yarn width of the woven fabric, a base fabric for an airbag used without coating The present invention relates to a base fabric for an air bag that has low air permeability and excellent storability.

[0002]

2. Description of the Related Art In recent years, airbags have become indispensable as a device for ensuring the safety of passengers in a vehicle, and the rate of attachment to the vehicle is increasing.

Although demands for improving the reliability of airbags as a safety device have been further increased, other required performances for airbags include cost reduction, compactness of airbag devices, and bags at the time of collision. Since there are various problems such as a request to prevent facial scratches on the occupant during deployment, for the airbag base fabric that constitutes the airbag, and thus for the airbag yarn,
Higher quality improvement is required.

To date, many techniques have been disclosed for realizing an airbag having excellent foldability and a small storage volume without deteriorating the characteristics of the airbag.

For example, Japanese Patent Application Laid-Open No. 1-441438 describes improvement in storability by using fibers having a strength of 8.5 g / d or more and a single yarn fineness of 3 denier or less. However, the technique described in the above publication is a technique relating to a so-called coated base fabric in which an elastomer such as chloroprene rubber is applied to the surface of the base fabric, and the flexibility of the coated base fabric is improved, resulting in excellent foldability. The effect is to obtain a base fabric for airbags. However, the improvement in terms of air permeability and storability was insufficient when the non-coated base fabric was used.

Further, in Japanese Patent Laid-Open No. 4-201650, a single yarn fineness of 1.0 to 10 is obtained as a base fabric for an airbag which is lightweight, excellent in flexibility and storability and excellent in mechanical properties.
Disclosed is an airbag base fabric using a polyamide multifilament composed of a plurality of single yarns having a modified cross section of 12 denier and a single yarn deformation degree of 1.5 to 7.0. However, the technique described in the above publication is not sufficiently improved in terms of air permeability and storability when the non-coated base fabric is used.

On the other hand, Japanese Patent No. 3144307 discloses that low air permeability and storability are improved by defining the yarn width at the time of forming the base fabric. However, since it is premised on the use of untwisted yarn, it is insufficient in terms of process passability and quality. Further, improvement in low air permeability and storability is insufficient.

Further, Japanese Patent No. 3085811 discloses that the low air permeability of a non-coated base cloth is improved by a calendar treatment. However, improvement is insufficient in terms of low air permeability and storability.

[0009]

SUMMARY OF THE INVENTION The present invention has been achieved as a result of studying the solution of the above-mentioned problems in the prior art. Therefore, the object of the present invention is to
An object of the present invention is to provide an air bag base cloth that has low air permeability and excellent storability in the air bag base cloth that is used without being coated.

[0010]

In order to achieve the above object, the airbag base fabric of the present invention is a non-coated airbag base fabric, and has a long axis length (a) and a short axis length of a single yarn. (B)
Using a flat cross section fiber having a flat cross section with an oblateness (a / b) of 1.5 to 8 determined from
0 to 2,400, the total fineness D1 (dtex) of the warp, the yarn width W1 (mm) of the woven fabric, and the total fineness D2 (dtex) of the weft.
And the yarn width W2 (mm) of the fabric satisfy the following equations (1) and (2). D1 / W1 = 770-1000 ... (1) D2 / W2 = 770-1000 ... (2).

The raw yarn used is a flat cross-section fiber having a single yarn fineness of 2 to 7 dtex and a total fineness of 200 to.
It is preferable that the yarn density is 600 dtex, the yarn strength is 7 to 9 cN / dtex, and the yarn elongation is 17 to 27%. Further, the obtained base fabric can be expected to have a more excellent effect by being subjected to a calendar treatment.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The airbag yarn of the present invention and the airbag base fabric using the same are described in detail below. The ratio (a / b) of the major axis length (a) and the minor axis length (b) of the flat cross-section fiber used for the airbag base fabric of the present invention,
That is, the oblateness is 1.5 to 8, preferably 2 to 6.
Here, the flatness ratio represents the degree of deformation of the flat cross section yarn, and is obtained by the following method. That is, 200 fibers
The cross section is photographed at a magnification of two times, the lengths of the long axis (a) and the short axis (b) of the single yarn are measured on the photograph, and the flatness is calculated from the a / b. Flatness = a / b. When the oblateness ratio is less than 1.5, the effect of using the flat cross section yarn cannot be sufficiently obtained, while when it exceeds 8, the effects of low air permeability and storability, which are the effects of the flat cross section yarn, are reduced.

The flat cross section yarn is usually elliptical, but may have a shape other than elliptical as long as the oblateness of 1.5 to 8 is satisfied. For example, it may be a left-right symmetric type such as a rectangle, a rhombus, or a cocoon type, or may be a left-right asymmetric type, or a combination of these types. May be.

The airbag base fabric of the present invention is required to have a cover factor of 1,600 to 2,400, preferably 1,800 to 2,200.
Here, the cover factor means cover factor: total fineness D1 (dtex) of warp, weave density N1 (book / 2.54)
cm), total fineness of weft D2 (dtex), weaving density N2
It is calculated by the following formula using (number of pieces / 2.54 cm). Cover factor = (D1 x 0.9) ^1/2 x N1 + (D
If the 2 × 0.9) ^1/2 × N 2 cover faucet is larger than 2400, the thickness of the woven fabric becomes large and the storability deteriorates. If the cover factor is less than 1600, low air permeability, which is a characteristic required for airbags, cannot be maintained.

The total fineness of the warp is D1 (dtx), the yarn width of the woven fabric in the warp direction is W1 (mm), and the total fineness of the weft is D2 (dt).
x), when the yarn width of the fabric in the weft direction is W2 (mm), the following two equations, D1 / W1 = 770 to 1000, preferably 800 to 900, D2 / W2 = 770 to 100
It is necessary to weave so that 0, preferably 800 to 900 are simultaneously satisfied. Here, the yarn width of the woven fabric means that a photograph is taken at a magnification of 200 as shown in FIG. 3 and the yarn widths of the weft yarn and the warp yarn are measured from the photograph. In the given formula, when D1 / W1 is larger than 1000, the overlapping of the single yarns becomes dense and the storability is deteriorated. On the other hand, when it is smaller than 770, the overlapping of the single yarns becomes sparse, and the maintenance of low air permeability becomes insufficient. By designing the width of the woven fabric, it is possible to provide a base fabric having a significantly improved air permeability and storability as a base fabric for a non-coated airbag.

Polyamide, polyester, aramid, wholly aromatic polyester and the like can be used as the fiber material of the yarn for the airbag of the present invention, and polyamide is particularly preferably used. Among the polyamides, polyhexamethylene adipamide is particularly preferably used.

The raw yarn used in the airbag of the present invention has a total fineness of 200 to 600 dtex and a single yarn fineness of 2 to 7 dte.
x, yarn strength 7-9 cN / dtex, yarn elongation 17
It is preferably 27% from the viewpoint of maintaining the strength of the base fabric and maintaining low air permeability.

The airbag base fabric of the present invention is a non-coated base fabric that is used without being coated with an elastomer or the like, and a sufficient effect can be obtained.

The characteristics of the airbag base fabric of the present invention include:
It is not particularly limited as long as it satisfies the mechanical properties and bag storability required for an airbag, but has a tensile strength of 400 N / cm or more, a tear strength of 100 N or more, and a thickness of 0.30 mm or less. Those satisfying the conditions are preferable.

Next, the manufacturing method will be described. As the synthetic fibers having a flat cross section used in the present invention, fibers made of various polymers can be used as described above, but polyamide fibers are preferable in order to obtain fibers having high strength and high toughness. In particular, a highly viscous nylon 66 polymer having a sulfuric acid relative viscosity of 3.0 to 4.0 is preferably used.

The polymer is melted, filtered and then spun through the pores of the die. The spun yarn is cooled and solidified, then an oil agent is applied thereto, and the spun yarn is wound and taken up by a take-up roller which rotates at a predetermined rotation speed. Then, the yarn is continuously wound as it is and wound around a Nelson roller which rotates at high speed, to perform drawing. In order to obtain a fiber having higher strength, it is preferable to perform multi-stage drawing of two or more stages. Further, it is preferable to set the final drawing roller temperature at 200 ° C. or higher and subject it to a heat treatment for drawing, and then subject it to a relaxation treatment and wind it up in order to obtain fibers having appropriate shrinkage properties. Along with the improvement of the yarn production efficiency, the winding speed is 2500 to 4500 m / min and the simultaneous drawing of 4 to 8 yarns is carried out by the direct spinning and drawing method.

Next, the raw yarn obtained by the above method is warped and woven. Further, when the base fabric obtained after weaving is calendered, the effect is great.

Generally, an efficient water jet loom is used for weaving, but a rapier room or an air jet loom can be used. As the condition for weaving, the tension when wefting is 0.5 to 1.0 cN / d
It is preferable to use tex. Thus, the airbag base fabric of the present invention is obtained.

The air bag base fabric of the present invention thus obtained has low air permeability and excellent storability.

Furthermore, it can be applied to applications other than airbags which require flexibility and low air permeability.

[0026]

EXAMPLES The present invention will be specifically described with reference to the following examples.

The definitions and measuring methods of the physical properties used in the text of the specification and the examples are as follows.

(1) Fineness: Measured according to JIS L-1013.

(2) Strength and elongation: JIS L-1013
The test length was 25 cm and the pulling speed was 30 cm / min.

(3) Flatness: Degree of deformation of a flat cross section yarn, which was determined by the following method.

The cross section of the obtained fiber was photographed at 200 times, the lengths of the long axis (a) and the short axis (b) of the single yarn were measured, and the flatness was calculated from the a / b. did. The average value of the measurements of 10 single yarns is used. (FIGS. 1 and 2) Flatness = a / b.

(4) Cover factor: Total fineness D of warp yarn
1 (dtex), weaving density N1 (pieces / 2.54 cm), total fineness of weft D2 (dtex), weaving density N2 (pieces / 2.5
4 cm) and calculated by the following formula. Cover factor = (D1 x 0.9) ^1/2 x N1 + (D
2 x 0.9) ^1/2 x N2.

(5) Tensile strength of base cloth: JIS L109
6 (method 6.12.1A).

(6) Tear strength of base cloth: JIS L109
6 (6.15.2A-2 method), and the average value in the warp direction and the weft direction was obtained.

(7) Aeration rate: JIS L1096 (6.
27.1A method).

(8) Ventilation amount after folding: After the folding treatment described in the text, the air permeability is determined according to JIS L1096.
It measured according to (6.27.1A method).

(9) Yarn width of woven fabric: A photograph was taken at a magnification of 200 as shown in FIG. 3, and the yarn widths of the weft yarn and the warp yarn were measured from the photograph.

(10) Thickness: JIS L1096 (6.
It measured according to 5).

(11) Bag storability: An air bag (I) having a capacity of 60 liters, as shown in FIG.
First, fold it into a bellows from left and right in the direction (II) four times to make it 150 mm, and then fold this folded product (II
I) is folded into a bellows from the top to the bottom in the direction of (II) four times, and a load (VI) of 4000 g is applied to the folded bag (V) as shown in FIG. 5 to determine the thickness of the bag at that time. The measurement was carried out, and the relative ratio when the thickness of the non-coated base fabric using the 470 dtex circular cross-section yarn of Comparative Example 1 was set to 100 was determined.

[Examples 1 to 6 and Comparative Examples 1 to 7] Nylon 66 chips having 98% sulfuric acid relative viscosity 3.7 at 25 ° C were melt-spun at 295 ° C using an extruder type spinning machine. As the spinneret, spinnerets having different flatness, shape, and number of holes are used, and a yarn is spun out from a spin pack having the spinneret, and the spin-spinning process shown in Tables 1 and 2 is performed.
0 dtex yarn was spun. The results of measuring the physical properties are shown in Tables 1 and 2.

Next, the yarns obtained by the respective methods are
Warping was performed at a speed of 200 m / min, and the weaving density was changed in a water jet loom (ZW303) manufactured by Tsudakoma, and the weaving was performed at a rotation speed of 800 rpm. Subsequently, each of the fabrics obtained above was treated with 0.5 g / l of sodium alkylbenzene sulfonate and 0.5 g / l of soda ash.
After soaking in a 80 ° C hot water bath containing 1 for 3 minutes, 130
It was dried at 0 ° C for 3 minutes and then heat-heat set at 180 ° C for 1 minute. Thus, a base cloth was obtained. The results of measuring the characteristics are shown in Tables 1 and 2.

Thereafter, two circular base cloths having a diameter of 725 mm were cut from each of the base cloths by a punching method, and a circular reinforcing base cloth of 200 mm in diameter made of the same base cloth was formed in the center of one of the circular base cloths. 3 sheets are laminated and the diameter is 110mm, 145mm, 175
470 dte of nylon 66 fiber for both upper and lower threads on mm line
Sewing was performed by lock stitching with a sewing thread composed of x / 1 × 3, and a hole having a diameter of 90 mm was provided to serve as an inflator attachment port. Furthermore, 255 from the center in the bias direction
A circular reinforcing base cloth of 75 mm in diameter made of the same base cloth is reciprocally placed at the position of mm, and the upper and lower threads are lined with 50 mm and 60 mm in diameter, and the upper and lower threads are 470 dtex / 1 × of nylon 66 fiber.
A sewing machine stitched with a sewing thread composed of 3 was sewn by a lock stitch, and two vent holes provided with holes having a diameter of 40 mm were provided.

Next, the reinforcing base fabric side of this circular base fabric is placed outside, and the other circular base fabric is overlapped with the warp axis shifted by 45 degrees, and the upper and lower yarns are nylon 6 on the circumference of diameters 700 mm and 710 mm. A sewing machine composed of 1400 dtex / 1 of 6 fibers was sewn with a double chain stitch, and then the bag was turned over to produce an airbag having a capacity of 60 liters. The results of measuring the characteristics are shown in Tables 1 and 2.

[Example 7] A base fabric obtained by spinning and weaving in the same manner as in Example 1 was heat-set, and then one-side calendering was performed with a heating roller having a surface temperature of 140 ° C and a pressure of 50 tons / 160 cm width. I went. After calendering, an airbag was manufactured in the same manner as in Example 1. The results of measuring the characteristics are shown in Tables 1 and 2.

[0045]

[Table 1]

[0046]

[Table 2]

From the results shown in Tables 1 and 2, the airbag base fabrics shown in the examples of the present invention are superior to the conventional airbag base fabrics in terms of storability and low air permeability. I understand.

[0048]

As described above, according to the present invention,
As a base fabric for an air bag that is used without being coated, it is possible to obtain a base fabric for an air bag having low air permeability and excellent storability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of a flat cross-section fiber.

FIG. 2 is a cross-sectional view of another example of a flat cross-section fiber.

FIG. 3 is a plan view of an example of a base cloth.

FIG. 4 is an explanatory flowchart showing a folding method of an airbag for a storability test.

FIG. 5 is an explanatory front view showing a method of applying a load after folding the airbag in the storability test.

[Explanation of symbols]

a Length of long axis of flat cross section yarn b Short axis length of flat cross section yarn W fabric thread width I airbag II Folding direction III, IV, V folded airbag VI load VII thickness

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Claims (4)

[Claims] 1. A base fabric for an uncoated airbag, which has a flatness (a) determined from a major axis length (a) and a minor axis length (b) of a single yarn.
/ B) A flat cross-section fiber having a flat cross section of 1.5 to 8 is used, the cover factor is 1,600 to 2,400, the total fineness D1 (dtex) of the warp and the yarn width W1 (m
m) and the total fineness D2 (dtex) of the weft and the yarn width W2 (mm) of the weft woven fabric satisfy the following formulas (1) and (2). D1 / W1 = 770-1000 (1) D2 / W2 = 770-1000 (2) 2. A flat yarn having a single yarn fineness of 2 to 7 dte.
x, total fineness of 200 to 600 dtex, raw yarn strength of 7 to
The base fabric for an air bag according to claim 1, wherein the base yarn for the airbag is 9 cN / dtex and the yarn elongation is 17 to 27%. 3. The airbag base fabric according to claim 1, wherein the flat cross-section fiber is polyamide. 4. The method according to claims 1 to 3, which has been subjected to a calendar processing.
The airbag base fabric according to any one of 1.