JP2001032145A - Woven fabric for uncoated air bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a woven fabric for an uncoated air bag having characteristics of a low air permeability under a low pressure at the time of starting development, high air permeation performances under a high pressure (>=40 kPa) in the latter period of the development and excellent in economical efficiency. SOLUTION: This woven fabric comprises thermoplastic filaments and has 0.1-0.6 air permeation deformation index PI of the thermoplastic filaments represented by the formula and <=1.0 L/cm2/min air permeability of the woven fabric under 20 kPa differential pressure. The air permeation deformation index PI is represented by PI=M(3)×(Den×ρ/f)1/2 [M(3) is the value (g/d) of tensile resistance at the time of 3% elongation of the filaments constituting the woven fabric; Den is the denier (d) of the filaments constituting the woven fabric; f is the number of single filaments (filaments) of a multifilament yarn constituting the woven fabric; ρ is the density (g/cm3) of the thermoplastic filaments].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric for non-coated airbags, which is one of the safety devices for automobiles.
An object of the present invention is to provide a fabric for an airbag, which can be made compact, has low air permeability, and has high air permeability at a high pressure (40 kpa or more).

[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. This gas causes the airbag to rapidly deploy and jump out in the direction in which the driver or passenger's body collides, especially preventing and protecting the head from 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).

[0007]

Since airbags need to be rapidly deployed in the event of a collision to protect the driver and passengers, low air permeability is required for non-coated airbag fabrics. In the latter period, it is required that the ventilation performance be high in order to prevent the abrasion of the face that occurs during deployment.

However, the conventional methods described in 1) to 4) above cannot provide a woven fabric satisfying such performance.

The present invention provides a nonwoven fabric for a non-coated airbag which has a low air permeability, a high air permeability under the condition of a high differential pressure (40 kpa or more) in the later stage of deployment, and is economically excellent. To provide.

[0010]

The present invention has the following structure in order to solve the problems which cannot be achieved by the above-mentioned conventional method. That is, the woven fabric for an airbag of the present invention is a woven fabric composed of thermoplastic fibers, and the ventilation deformation index PI of the thermoplastic fibers is 0.1 to 0.6,
And the air permeability of the woven fabric at a differential pressure of 20 kPa is 1.0 (L
/ Cm2 / min) or less.

The ventilation deformation index PI is expressed by the following equation (Equation 2).

[0012]

## EQU2 ## PI = M (3) × (Den × ρ / f) ^1/2 M (3): Tensile resistance value (g / d) at 3% elongation of the fabric constituting the fabric. Den: The denier (d) of the weave constituting the fabric. f: Number of single filaments of the multifilament constituting the woven fabric (pieces) ρ: Density of thermoplastic fiber (g / cm3).

A feature of the nonwoven fabric for non-coated airbags of the present invention is that the yarn formed by weaving a fabric obtained by weaving using a thermoplastic fiber and performing shrinkage treatment has a ventilation deformation index of a warp yarn and a weft yarn. Both are adjusted to 0.1 to 0.6.

The ventilation deformation index PI of the present invention is obtained by converting the ratio between the tensile resistance value of a single fiber and the surface area of the single fiber at the time of minute (3% elongation) deformation of the fiber into an index by the above equation (Equation 2). . That is, by adjusting the balance between the fiber diameter used for the woven fabric and the elastic modulus of the fiber that applies pressure to the fiber, a non-coated airbag fabric having desired properties can be obtained. If the ventilation deformation index is smaller than 0.1, 20
At the time of the differential pressure of kPa or less, the deformation of the fiber increases, and the air permeability increases from the time of the relatively low differential pressure. Also, when the air permeability deformation index exceeds 0.6, the air permeability at the time of the differential pressure of 50 kPa increases. It cannot be increased, which is not preferable.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION It is necessary that the thermoplastic fiber used as the raw yarn used in the present invention has a boiling water shrinkage of 5 to 15%. If the boiling water shrinkage of the yarn 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 boiling water shrinkage of the yarn is 5 to 15%.
Degree, but more preferably 8 to
It is 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 shrinkage 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 ventilation deformation index of the constituent fibers of the woven fabric to 0.1 to 0.6.

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 of 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 is preferably 4d or less.

If the total fineness is less than 100 d, the tensile strength and tear strength of the fabric are insufficient, and if it exceeds 700 d, the flexibility of the woven fabric is impaired, which is disadvantageous for storage, and the airbag is compact. It is difficult to respond to the demands.

[0021] Even when the single-fiber fineness exceeds 8d, the flexibility of the woven fabric is impaired, which is disadvantageous for storability.

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 greater than 2.5 L / cm2 / min, the expandability of a non-coated airbag will be insufficient.

The yarn is preferably substantially non-twisted or sweet-twisted, and more preferably, untwisted yarn is used. This is because, when trying to obtain a low-permeability woven fabric using a low single-filament yarn, if twist is added, the expansion of the single yarn is hindered, and it is difficult to reduce the air permeability.

[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 a permeation meter manufactured by OEM System Co., Ltd. Boiling water shrinkage: JIS L1013 Hot water shrinkage B method 1
00 ° C 3% tensile resistance: Initial load 0.0 using a tensile tester
A tensile test was conducted at 1 g / d to measure the strength at 3% elongation. Aeration performance value: The differential pressure was 10, 20,
The air permeability at 40 and 50 kPa is measured, and the air permeability value a / b (APEA / b) is calculated by the equation (Equation 3). The larger the air permeability value, the higher the air permeability.

[0025]

APEa / b = log (Pa / Pb) / log
(A / b). Pa: air permeability measured at a (kPa) (L / cm2 /
min). Pb: air permeability measured at b (kPa) (L / cm2 /
min). APEa / b: aeration performance value between a and bkPa (a>
b).

Example 1 Non-twisted 420d / 72 warp
f (single yarn fineness: 5.8d), a raw yarn having a boiling water shrinkage of 9.5%, and a non-twisted 420d / 72f (single yarn fineness: 5.8)
d), using a raw yarn having a boiling water shrinkage of 9.5%, weaving with plain weave, shrinking with boiling water, drying and finishing at 140 ° C, and making the greige 6.0% vertical and 5.5 wide. % Shrinkage was set to obtain a non-coated airbag fabric having a warp density of 55 lines / in and a weft density of 55 lines / in. Table 1 shows the physical property evaluation results of the non-coated airbag fabric.

Example 2 Non-twisted 420d / 72 warp
f (single yarn fineness: 5.8 d), the original yarn and the weft having a boiling water shrinkage ratio of 10.0% are untwisted 420d / 72f, and the boiling water shrinkage ratio is 6.
After weaving with plain weave using 0% of the original yarn, shrinking with boiling water, drying and finishing at 130 ° C, the greige is shrunk to 5.5% in length and 4.0% in width, and densified. 54 / i
n, a woven fabric for a non-coated airbag having a weft density of 54 strands / in was obtained. Table 1 shows the physical property evaluation results of the non-coated airbag fabric.

Example 3 Non-twisted 315d / 72 in warp
f (single yarn fineness 4.4d), one kind of raw yarn having a boiling water shrinkage of 10.5%, and a weft yarn of 315d / 72f (single yarn fineness 4.4d) with no twist, and a boiling water shrinkage of 10.5%. Using raw yarn,
After weaving with plain weave, after shrinking with warm water of 90 ° C, 140
5. Dry set finish at ℃, the greige is 7.5% horizontal
Shrinks by 5% and has a density of 63 lines / h1 and a weft density of 62 lines / in
Was obtained. Table 1 shows the physical property evaluation results of the non-coated airbag fabric.

(Comparative Example 1) Non-twisted 420d / 72 in warp
f (single yarn fineness: 5.8d), using one kind of untwisted 420d / 72f and one type of weft with a boiling water shrinkage of 6% and a plain weave using a loom. After weaving, shrink with boiling water, dry finish at 150 ° C, shrink the greige paper by 6% each in the vertical and horizontal directions, 55 densities / in, 55 degrees weft density /
in of non-coated airbag fabric was obtained. Table 1 shows the physical property evaluation results of the non-coated airbag fabric.

Comparative Example 2 Non-twisted 315d / 72f (single yarn fineness 4.4d) warp;
After weaving in a plain weave using a raw yarn having a boiling water shrinkage of 10.5%, non-twisting 315d / 72f and a boiling water shrinkage of 10.5 as the weft, and shrinking with boiling water, the resulting yarn is subjected to shrinkage. After drying and setting at ℃, the greige fabric was shrunk by 10.0% for each length and width to obtain a fabric for non-coated airbag having a density of 63 yarns / in and a weft density of 62 yarns / in. Table 1 shows the physical property evaluation results of the non-coated airbag fabric.

Comparative Example 3 Non-twisted 315d / 72f (single yarn fineness 4.4d) warp;
Using a raw yarn with a boiling water shrinkage of 9.5%, and a non-twisted 3
After weaving with a plain weave using 15d / 72f and a boiling water shrinkage rate of 9.5%, it is subjected to boiling water shrinkage processing, set at 150 ° C. and dried, and the greige is shrunk by 6.0% in length and 3.2% in width. Thus, a woven fabric for a non-coated airbag having a warp density of 63 strands / in and a weft density of 62 strands / in was obtained. Table 1 shows the physical property evaluation results of the non-coated airbag fabric.

Comparative Example 4 Non-twisted 4205d / 72f warp (single yarn fineness 5.8)
d) Using a raw yarn having a boiling water shrinkage of 6.0%, weaving a plain weave using a non-twisted 420d / 72f and a boiling water shrinkage of 6.0% as the weft, and then subjecting the yarn to plain water weaving, followed by boiling water shrinkage processing. , Dry set finish at 150 ° C, 5.2% for the greige, 2.6% for each horizontal
The fabric was shrunk to obtain a fabric for a non-coated airbag having a warp density of 63 wires / in and a weft density of 62 wires / in. Table 1 shows the physical property evaluation results of the non-coated airbag fabric.

[0033]

[Table 1] As is clear from the results in Table 1, the woven fabric for a non-coated airbag of the present invention is a woven fabric with low air permeability,
0/40: the ventilation performance value in the section where the differential pressure is 50 kPa and 40 kPa) is as high as 1.4 or more, indicating that the ventilation performance at high pressure is better than that of the comparative example.

[0034]

According to the present invention, an economically superior non-coated non-coated airbag which retains the required mechanical properties as a non-coated airbag fabric, has a low air permeability, and has good air permeability at high pressures. A fabric for an airbag can be provided.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D054 CC26 CC27 CC45 FF18 FF20 4L048 AA24 AA34 AA42 AA50 AA51 AB07 AB13 BA01 BA02 CA11 CA15 DA25 EB05

Claims (3)

[Claims] 1. A woven fabric composed of thermoplastic fibers, wherein the thermoplastic fiber has a ventilation deformation index PI represented by the formula (Equation 1) of 0.1 to 0.6, and the woven fabric Air permeability at a differential pressure of 20 kPa is 1.0 (L / cm2 / mi)
n) A low-permeability non-coated airbag fabric characterized by the following. ## EQU1 ## PI = M (3) × (Den × ρ / f) ^1/2 M (3): Tensile resistance value at 3% elongation of the fabric constituting the fabric (g / d) Den: Fabric Denier of constituent textiles (d) f: Number of single filaments of multifilaments constituting textile (number) ρ: Density of thermoplastic fiber (g / cm3) 2. The thermoplastic fiber has a boiling water shrinkage of 5-1.
The woven fabric for a low-permeability non-coated airbag according to claim 1, wherein the woven fabric has a ventilation deformation index adjusted by shrinkage treatment after weaving. 3. The nonwoven fabric for a low-permeability non-coated airbag according to claim 1, wherein the thermoplastic fiber is a polyamide fiber.