JPH0754238A - Uncoated fabric for air bag - Google Patents

Abstract

PURPOSE:To provide an uncoated base fabric for air bags, excellent in lightness and housing properties and softness and having low air permeability at a low cost. CONSTITUTION:This uncoated base fabric for air bags is composed of a woven fabric using polyamide fiber or polyester fiber having a hollow cross section at 5-50% percentage of hollowness of the fiber as a material and the characteristic of the base fabric is an air permeability thereof as low as <=0.5cc/cm<2>sec. The polyamide fiber having the hollow cross section as the material for the woven fabric is any one selected from nylon 6, nylon 66 and nylon 46 and the fiber having $<=500 denier size and <=4 denier single filament size is used. The polyester fiber having the hollow cross section as the material for the woven fabric is any one of polyethylene terephthalate or polyethylene naphthalate and the fiber having <=500 denier size and <=4 denier single filament size is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-coated base fabric for an air bag, and more particularly to a non-coated base fabric for an air bag which is excellent in lightness, flexibility and storability and has low air permeability. It is a thing.

[0002]

2. Description of the Related Art In recent years, an airbag has been rapidly installed as a vehicle occupant protection safety device.

Since an airbag is usually stored in a narrow space such as a steering wheel and an instrument panel, it is required to reduce the storage volume.

Therefore, the required performance of the airbag base cloth is that it has the best foldability and excellent storability as far as the mechanical properties are satisfied. Efforts have been made in the past to minimize the storage capacity of airbags.

For example, in rubber-coated base fabrics, the shift from polychloroprene to silicone-based rubbers is progressing. This is because the use of silicone-based rubbers makes it possible to reduce the coating amount of the rubber coat and to provide a flexible rubber-coated substrate. Because you can make a cloth.

Another performance requirement for the airbag base fabric is that the cost of the base fabric itself is low. That is, in order to ensure the safety of the occupants of a vehicle, it is desired to increase the mounting rate of airbags, but as one of the driving forces, it is desired to reduce the price of the entire airbag system. Of.

Therefore, further cost reduction of the air bag base cloth has been taken up as an issue, and development of an uncoated base cloth for an air bag, which has a high possibility of cost reduction, has been under way.

Further, the non-coated base fabric for airbags is advantageous in terms of flexibility, storability and light weight, and there is a strong demand for early establishment of technology as a next-generation airbag base fabric.

From this point of view, many proposals have been made regarding the base fabric for non-coated airbags, and a typical conventional technique is, for example, JP-A-3-137245.
JP-A-64-70247 and JP-A-3-70247.
The techniques described in Japanese Patent Laid-Open No. 134245 and the like are mentioned.

That is, in the technique described in Japanese Patent Laid-Open No. 122752/1989, in order to control gas permeability, which is an important characteristic as a base fabric for a non-coated airbag, the base fabric itself is a high-density fabric, and further, Disclosed is a base fabric for a non-coated airbag produced by applying shrinkage processing, heat-setting calendering processing, or the like.

In the technique disclosed in Japanese Patent Laid-Open No. 64-70247, the air permeability is 5 cc / cm by calendering a base fabric having a basis weight of 250 g / m ² or less.
Disclosed is a base fabric for a non-coated air bag of ² / sec or less.

Further, the technique described in Japanese Patent Application Laid-Open No. 3-134245 discloses a non-coated base fabric made of a woven fabric having a symmetrical structure subjected to calendering and having a fineness of 300 to 400 dtex and a high shrinkage yarn. .

The uncoated base fabric for airbags described in the above publications is lighter in weight, more flexible, and easier to store than the conventional coated base fabric for airbags coated with chloroprene rubber or silicone rubber. It has been shown that it has excellent properties and that it has practically sufficient mechanical properties and non-breathability.

However, the conventional non-coated base fabrics for low-air-permeability airbags described in the above publications are woven with a high-density fabric or have a relatively high-density fabric in order to achieve low air-permeability. Since it was manufactured by weaving, and then further shrinking or calendering it, it was not sufficiently satisfied with the required performance for cost reduction.

That is, in weaving a high-density fabric,
In particular, when a fine fiber, for example, a fiber having a denier of 420 denier or less is used in order to obtain an uncoated base fabric that is excellent in lightness, flexibility and storability, weaving efficiency is significantly reduced. It was difficult to obtain the merit of lowering the price that was expected in the above, and this point was a bottleneck in the development of non-coated base cloth.

On the other hand, when a low-permeability base cloth is obtained by applying shrinkage processing or calendering, a new step is added to the base cloth manufacturing process, so that the equipment and the increase in the work amount are low. It was an obstacle to pricing.

[0017]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the above-mentioned conventional techniques.

Therefore, an object of the present invention is to provide a low-priced air bag base cloth which is excellent in lightness, flexibility and storability and has low air permeability.

The inventors of the present invention have conducted extensive studies in order to achieve the above object. As a result, even a non-coated base fabric for an airbag made of a high-density woven fabric using fine fiber has a specific fiber as a raw material. The inventors have found that by selecting a fiber having a hollow cross section, a non-coated base fabric having the above-mentioned performance can be obtained at a low price without lowering the weaving efficiency, and have reached the present invention.

[0020]

That is, the non-coated base fabric for an air bag of the present invention is a non-air bag fabric made of a woven fabric made of polyamide fiber or polyester fiber having a hollow cross section with a hollow ratio of 5 to 50%. A base fabric having an air flow rate of 0.5 cc / cm ² / sec
It is characterized by the following low air permeability.

In the non-coated base fabric for an airbag of the present invention, the polyamide fiber having a hollow cross section as a woven material is any one selected from nylon 6, nylon 66 and nylon 46 and has a fineness of 500 denier. It is characterized in that the single yarn fineness is 4 denier or less.

Further, in the non-coated base fabric for an air bag of the present invention, the polyester fiber having a hollow cross section as a woven material is either polyethylene terephthalate or polyethylene naphthalate and has a fineness of 5
It is characterized in that the fineness is 100 denier or less and the single yarn fineness is 4 denier or less.

The non-coated base fabric for airbag of the present invention is
It has excellent properties such as light weight, flexibility and storability and low air permeability, and the material fiber of the woven fabric constituting the base fabric has a hollowness of 5 to 50%, preferably 15%.
It is characterized by being composed of polyamide fibers or polyester fibers having a hollow cross section of -40%.

The term "hollowness" as used in the present invention means a value in which the ratio of the hollow area to the area surrounded by the outer periphery of the fiber cross section is expressed as a percentage.

In the airbag non-coated base fabric of the present invention, by using the hollow cross-section fiber as the fabric material, excellent lightness, flexibility and storability are substantially maintained and the fabric density is remarkably increased. And low air permeability equivalent to that of conventional high-density fabrics, eg 0.5 cc / cm ²
It is possible to achieve a low air flow rate of less than / sec.

Generally, a cover factor (K) is used as a measure of the fabric density, and this cover factor (K) is obtained from the product of the fabric constituent density and the square root of the fineness of the fiber yarn by the following formula. K = Nw × Dw ^1/2 + NF × DF ^1/2 where Nw: warp density (threads / inch) Dw: warp denier NF: weft density (threads / inch) DF: weft denier The above cover factor (K) is It means the volume occupancy of the fiber in the woven fabric, but it actually changes depending on the density of the fiber. That is, even if the fineness is the same, if the density of the fiber is low, the volume occupancy rate becomes high.
When used as a non-coated base fabric for an airbag, low air permeability is easily obtained. The fiber density varies depending on the material, but can be greatly changed even if the same material is used and the hollow cross-section fiber characterized by the present invention is adopted.

In the present invention, the hollow cross-section fiber used as the material fiber of the woven fabric has a hollowness of 5 to 50%, preferably 15 to 40%.

When the hollow ratio of the hollow cross-section fiber is less than 5%, the apparent density of the fiber does not increase, and the desired effect cannot be sufficiently obtained. On the other hand, when the hollow ratio exceeds 50%, the desired improvement effect is sufficient, but the mechanical properties of the airbag base fabric are somewhat inferior, which may cause a problem in practical use.

The design of the hollow ratio of the hollow cross-section fiber used in the non-coated base fabric for airbag of the present invention is as follows, for example.

In contrast to the conventional high-density woven fabric obtained by using 420 denier polyamide fiber with a warp and weft density of 55 × 55 yarns / inch, a hollow cross-section polyamide fiber having a hollow ratio of 20% was used. Weft density is 46 × 4
By making the woven fabric of 6 yarns / inch, both of them have almost the same low air permeability.

Alternatively, a low breathability woven fabric equivalent to the above can be obtained by using 315 denier hollow cross-section polyamide fiber having a hollowness of 33% and a warp and weft density of 55 × 55 yarns / inch. .

Therefore, when such a woven fabric is used as an uncoated base fabric for an airbag, it is excellent in lightness, flexibility and storability as well as having low air permeability, and has mechanical properties equal to or higher than those of the conventional rubber coated base fabric. It is possible to achieve practically sufficient performance.

The cross-section of the hollow cross-section fiber used in the present invention is generally a circle or a shape close to a circle in both the outer peripheral shape and the hollow part. However, the mechanical properties and hollowness of the non-coated base fabric for an air bag of the present invention are Various shapes can be selected as long as the ratio is satisfied. For example, it can be selected from the cross-sectional shapes described in Textile Engineering [II], Textile Engineering [II], Fiber Manufacturing / Structure and Physical Properties, page 6 edited by The Japan Textile Society.

The hollow section polyamide fiber used in the non-coated base fabric for an air bag of the present invention is any one selected from nylon 66, nylon 6 and nylon 46.

As the hollow cross-section polyamide fiber, it is usually preferable to use a fiber composed of a single polymer, but it may contain 10% by weight or less of a copolymerization component. In particular, in the case of nylon 46 fiber, it is difficult to make a yarn with a homopolymer as it is because of its high melting point and high crystallinity. Therefore, a copolymerized polyamide fiber containing about 5% by weight of a copolymerization component, for example, ε-caprolactam is rather preferable. preferable.

The hollow-section polyester fiber used in the non-coated base fabric for an airbag of the present invention is either polyethylene terephthalate or polybrylene terephthalate, which contains a homopolymer or 10% by weight or less of a copolymerization component. It may be any of the polymers.

The hollow cross-section fiber according to the present invention has the mechanical properties of the base cloth, that is, the strength of the base cloth capable of withstanding the instantaneous expansion of gas, particularly impact strength, burst strength, tear strength, etc., and the expanded airbag. It is necessary to use a polymer having a high degree of polymerization in order to satisfy the energy for absorbing the impact when the vehicle hits the occupant. Specifically, in the case of polyamide fiber, the relative viscosity of sulfuric acid (ηr) must be 3.0 or more, and in the case of polyester fiber, the intrinsic viscosity ([η]) must be 0.8 or more.

Further, the hollow cross-section fiber according to the present invention is subjected to heat history during the fiber manufacturing process and the base cloth manufacturing process, and deterioration during storage and use as a product, for example, thermal oxidation deterioration in the case of polyamide fiber. It is preferable to add an antioxidant for the purpose of preventing oxidative deterioration such as photooxidative deterioration, and to reduce the carboxyl terminal group concentration in the case of polyester fiber for the purpose of preventing hydrolysis.

As an antioxidant for polyamide, copper iodide,
Inorganic and organic acid copper salts such as copper bromide, copper chloride, copper acetate, copper pyrophosphate, and copper stearate are used as copper in an amount of 10 to 10.
Add 300 ppm, preferably 20-150 ppm,
Alkali metal halides such as potassium iodide, potassium bromide, potassium chloride, sodium iodide, sodium bromide, sodium chloride, lithium iodide, lithium bromide, lithium chloride, or earth metal halides, or quaternary It is desirable to contain an ammonium halide salt or the like together in an amount of 0.05 to 0.5% by weight. Furthermore, if necessary, an organic or inorganic phosphorus compound may be contained as phosphorus in an amount of 10 to 500 ppm.

In the case of polyester fiber, especially polyethylene terephthalate fiber, the carboxyl end group concentration is 30 eq / 10 ⁶ or less for the purpose of preventing hydrolysis.
It is preferably 20 eq / 10 ⁶ or less. Polyethylene terephthalate fibers with few carboxyl end groups are used for low temperature polymerization, epoxy compounds,
It can be obtained by a method of adding a carbodiimide compound, an oxazoline compound or the like as a terminal blocking agent in the spinning step.

The polyamide or polyester fiber having a hollow cross section according to the present invention has a fineness of 500.
Denier or less and single yarn fineness of 4 denier or less.

The fineness is preferably as small as possible from the viewpoints of lightness, flexibility and storability, and is selected within a range that satisfies the mechanical properties of the non-coated base fabric for airbag. A preferred fineness range is 420 to 210 denier.

Here, when the fineness is less than 210 denier, the mechanical properties of the obtained base fabric are inferior, while when the fineness exceeds 500 denier, the effect intended by the present invention cannot be sufficiently obtained. This is because it may not be possible to efficiently weave with a high-speed WJL suitable for weaving the non-coated base fabric for an airbag of the invention, which is not preferable.

The fineness of the single yarn is more effective in terms of flexibility and storability of the base fabric, so the finer the fineness is, the more preferable the fineness is 4 denier or less, usually 0.5 to 4 denier. And

Here, if the single yarn fineness exceeds 4 denier, the difference in intended improvement effect tends to be small compared with the conventional base fabric, which is not preferable.

The hollow cross-section fiber of the present invention characterized by the above and the non-coated base fabric for an air bag obtained by using the hollow cross-section fiber have the following excellent physical properties.

“Physical properties of raw yarn” (1) Tensile strength (T) T ≧ 8.0 g / d (Measuring method: JIS L1017) (2) Elongation (E) E ≧ 18% (Measuring method: JIS L1017) ( 3) Dry heat shrinkage (ΔSD) ΔSD ≦ 12% (Measurement method: JIS L1017) (4) Boiling water shrinkage (ΔSW) ΔSW ≦ 10% (Measurement method: JIS L1017) “Physical properties of base fabric” (1) Tensile strength Strength (S) S ≧ 160 kg / 3 cm (Measurement method: JIS K6328 5.3.5, strip method) (2) Elongation at break (E) 15 ≧ E ≧ 35% (Measurement method: JIS K6328 5.3.5) , Strip method) (3) Tear strength (TS) TS ≧ 15 kg (Measurement method: JIS K6328 5.3.6, Murren method) (4) Air flow rate (P) P ≦ 0.5 cc / cm ² / sec (measurement Method: JIS L1096 6.27A method (5) Softness (SF) SF ≦ 50 mm (measurement method: JIS L1096 450 cantilever method).

The characteristics (1) to (5) of the non-coated base cloth for an air bag of the present invention are substantially the same as those disclosed as the conventional improved non-coated base cloth for an air bag. .

Among the above characteristics, the air permeation amount (P) is at a sufficient level when the non-coated base fabric for airbag is used as a substantially non-permeable base fabric.

Further, in the case of the non-coated base fabric for an air bag using the hollow cross-section fiber of the present invention, the ventilation amount can be controlled by the fabric design such as the fineness of the fiber, the hollow ratio and the fabric density, and in some cases, further It is also possible to combine shrinkage processing and calendar processing after weaving.

The non-coated base fabric for an air bag of the present invention is characterized by being lighter than the conventional base fabric while having the above-mentioned base fabric characteristics. That is, when the fiber material and the fabric density are the same, the weight reduction corresponding to the hollow ratio of the hollow cross-section fiber is achieved.

Next, a method for manufacturing the non-coated base fabric for an air bag of the present invention will be outlined.

The raw material yarn used for producing the base fabric for a non-coated airbag of the present invention is a polyamide selected from nylon 6, nylon 66 and nylon 46, or a polyester selected from polyethylene terephthalate and polyethylene naphthalate. It is produced by spinning and drawing.

In the melt spinning step, the polymer is melt-spun through a spinneret for hollow cross-section fibers, but a spinneret designed to obtain a circular or nearly circular cross-sectional shape at both the outer circumference and the hollow portion is usually used.

Next, the spun yarn is cooled and solidified, and then an oil agent is applied. Normally, the amount of oil attached to the fiber is 0.3-
It is 1.5% by weight, usually 0.5 to 1.0% by weight.

The yarn provided with the above oil agent is preferably continuously sent to the drawing step and drawn and heat-treated. For the stretching, a multi-stage hot stretching method with two or more stages is usually adopted.

The drawn yarn is heat set and wound up, but immediately before winding up, the yarn is interlaced to bundle the filaments together. The interlacing is performed by spraying a high-pressure fluid such as high-pressure air or steam from the outer circumference of the yarn through a nozzle.

A part of the raw yarn produced by the above method is sent to the warping step and rewound into a warping beam for warp,
A part of the yarn is prepared as weft and woven with WJL.

The non-coated base fabric for an airbag of the present invention is
A low-breathable woven fabric with an air flow rate of less than 0.5 CC / cm ² / sec is used, but it is not necessary to use an exceptionally high-density woven fabric. That is, the density of the non-coated base fabric for an air bag of the present invention can be reduced by the hollow ratio, compared to the high fabric density conventionally required to obtain a fabric having a low air permeability.

Weaving by WJL can be efficiently performed at a weft driving speed of about 1000 m / min or more, preferably 1200 m / min or more.

The weaving machine woven as described above is sent to the heat setting step as it is without heat treatment, and heat set.

Further, in order to control the air permeability of the non-coated airbag base fabric, or to control the feel and the flexibility, calendering may be performed on one side or both sides of the raw fabric.

The base fabric for airbags of the present invention produced by the above method has the above-mentioned base fabric characteristics, and is particularly lightweight and weaving cost in comparison with conventional non-coated base fabrics for airbags. Is advantageous.

The non-coated base fabric for an air bag of the present invention having the above characteristics can be used for both the driver's seat and the passenger's seat.

Next, one embodiment of the present invention will be specifically described with reference to the following examples.

[0066]

【Example】

[Examples 1 to 5] Relative viscosity of sulfuric acid (sample concentration 1% by weight, 2
(5 ° C) is 3.5, and phosphorus is 100 pp as an antioxidant.
m, 80 ppm of copper and 0.1% by weight of potassium iodide
The contained nylon 66 chips were melted by an extruder type spinning machine. The molten polymer was filtered in a spin pack and spun through the spinneret pores. As the die, a die having 144 holes with which circular hollow cross-section fibers were obtained on both the outer circumference and the hollow portion was used.

The spun yarn passed through a slow cooling zone immediately below the spinneret and was then cooled and solidified with cold air.

Then, an oil agent diluted to 20% by weight with a higher hydrocarbon having a carbon number of C13 was applied to the above yarn, and the yarn was taken up by a take-up roll at a speed of 900 m / min. The undiluted oil solution was applied while stretching 5% of the yarn between the rolls.

The oil agent was applied to the raw yarn in an amount of about 1% by weight, about 0.2% by weight before the take-up roll, and the rest between the take-up roll and the yarn feeding roll.

Next, the yarn is sent to the drawing process and continuously
After the stepwise stretching, a relaxation heat treatment was performed. In this case, the take-up roll is not heated, the yarn feeding roll is 60 ° C., the first
The stretching roll temperature is 120 ° C., and the second stretching roll temperature is 24.
The relaxing roll temperature after stretching was 0 ° C. and 120 ° C.

The stretching ratio was 3.56 for the first step and 1.25 for the second step, and the relaxation rate in the relaxation heat treatment was 8%.

The drawn and heat-treated yarn is interlaced immediately before winding and the number of entanglements is about 40 per 1 m.
I wound it up so that it would be a good result.

The raw yarn obtained by the above method is 420D-1
With 44 fil, the strength was 9.2 g / d, the elongation was 21%, and the boiling water shrinkage was 6.0%.

A part of this yarn was used as a warp beam. A part of the weft was woven using WJL manufactured by Tsuda Koma Co., Ltd. at a weft driving speed of 1000 m / min. The warp and weft densities were variously changed as shown in Table 1 to obtain raw fabrics having different fabric densities.

The greige machine was heat-set as it was at 180 ° C. without going through the refining step to obtain a non-coated base cloth for airbag. (Example 1) Further, the fineness and the single yarn fineness of the raw yarn, the kind of the raw material polymer (polyethylene terephthalate [PET] ... Example 5), the yarn making conditions, the weaving conditions and the like were changed as shown in Table 1 to 4 A variety of non-coated base fabrics for airbags were obtained.
(Examples 2 to 5) The performance of each of the obtained non-coated base fabrics for airbags was evaluated as a base fabric for airbags, and the results are also shown in Table 1.

[0076]

[Table 1] [Comparative Example 1] In the same yarn making method as in Example 1, only the spinneret 72
Using holes, weaving and weaving were carried out to obtain an uncoated base fabric for airbags. The performance evaluation of the obtained non-coated base fabric for airbag as a base fabric for airbag is shown in Table 2.
It was shown to.

[Comparative Examples 2 to 5] Spinning and weaving were carried out in the same manner as in the above Examples except that the hollow spinneret used in Examples 1 to 5 was changed to a normal circular cross section spinneret (solid spinneret). ,
As shown in Table 2, four types of non-coated base fabrics for airbags having different fabric densities were obtained.

The performance of the obtained non-coated base fabric for airbag was evaluated as an airbag base fabric, and the results are also shown in Table 2.

[0079]

[Table 2] As is clear from the magnifications in Tables 1 and 2, the non-coated base fabrics for air bags made of the hollow cross-section fibers obtained in Examples 1 to 5 of the present invention have low air permeability even when the fabric density is relatively low. It can be seen that it has been achieved, the mechanical properties are at a practical level, and because it is lightweight and flexible, it has excellent storability.

On the other hand, in the case of the conventional non-hollow circular cross-section fibers (solid fibers) (Comparative Examples 2 to 5), high density weaving or calendering was applied to obtain low air permeability. Therefore, it is necessary to increase the cost as compared with the present invention.

[0081]

EFFECT OF THE INVENTION The non-coated base fabric for air bags using the hollow cross-section fiber of the present invention is excellent in lightness, flexibility and storability, and is remarkably superior to the conventional non-coated base fabric for air bags. It is lightweight.

Further, the non-coated base fabric for airbags of the present invention has a sufficiently low fabric density unlike the conventional non-coated base fabrics for airbags, or does not require a shrinking process and a calendering process in combination to obtain a sufficiently low fabric density. Since air permeability is achieved, it has an advantage that it can be obtained at a low base cloth manufacturing cost.

The non-coated base fabric for airbag of the present invention is
Since it is advantageous in terms of both the above performance and manufacturing cost,
It can greatly contribute to the improvement of the air bag installation rate, which is desired for protecting passengers of a vehicle.

Claims (3)

[Claims] 1. A non-coated base fabric for an airbag, which is made of a woven fabric made of polyamide fiber or polyester fiber having a hollow cross section with a hollow ratio of 5 to 50%, and the ventilation amount of the base fabric is 0.5 cc / A non-coated base fabric for an air bag, which has a low ventilation of cm ² / sec or less. 2. The polyamide fiber having a hollow cross section is any one selected from nylon 6, nylon 66 and nylon 46, and has a fineness of 500 denier or less and a single yarn fineness of 4 denier or less. The non-coated base fabric for an airbag according to claim 1. 3. A polyester fiber having a hollow cross section,
The non-coated base fabric for an airbag according to claim 1, which is either polyethylene terephthalate or polyethylene naphthalate and has a fineness of 500 denier or less and a single yarn fineness of 4 denier or less.