JPH06306728A - Base cloth for air bag - Google Patents

Abstract

PURPOSE:To obtain a base cloth for air bag having low air-permeability and high flexibility and free from resin-coating layer on the surface by weaving a cloth with a specific polyester multifilament at or above a specific cover factor. CONSTITUTION:The objective base cloth is composed of an essentially nontwisted polyester multifilament yarn having a total denier of >=220 and <450de, single fiber denier of >=0.6 and <3de, a strength of >=8g/de, an elongation of >=12%, a dry-heat shrinkage of >=5.0 and <=12% at 150 deg.C and 30min, a maximum heat-shrinkage stress of >=0.20g/de and an interlocking number of >=20. A cloth having a cover factor K of >=20,000 is formed by using the multifilament yarn. The cover factor K is defined by the formula K= NWXDW<0.5>+NFXDF<0.5> [NW and NF are density (number/inch) and fineness (de) of warp; DW and DF are density and fineness of the weft]. A base cloth for air bag having a tensile strength of >=170kg/3.0cm, a tear strength of >=18kg/2.54cm, a flexibility of <=70mm (centilever) and an air permeability of <=1.0cm<3>/sec/cm<2> at a pressure drop of 1.27cm can be produced by this process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base fabric for airbags which is not coated with resin. More specifically, the present invention relates to a base fabric for an airbag that has both low air permeability and flexibility, and has less fluff and excellent processability.

[0002]

2. Description of the Related Art In recent years, airbags have become extremely popular as safety devices for protecting passengers of automobiles.

As a requirement for a base fabric for an air bag, first of all, it is necessary to have a low gas permeability and a mechanical strength sufficient to smoothly expand upon impact. Furthermore, it is also necessary that the human body, especially the face, should not be scratched when inflated when it is inflated, that it can be stored compactly, and that there is no dimensional change during installation on the vehicle body for a long period of time.

Typical air bag base fabrics currently being developed are single yarn fineness 4d to 7d and total fineness 400D to 100.
A base cloth made of 0D nylon yarn and a base cloth further coated with a resin such as chloroprene or silicone (hereinafter referred to as a coated product) are used.

Recently, however, the weight and compactness
Fabrics in which the surface of the fabric is not coated with resin have been proposed in consideration of costs.

However, in order to suppress the gas permeability without coating the resin, it is necessary to woven the cloth at a high density, and as a result of the increased basis weight, the flexibility of the cloth is hardly improved. .

On the other hand, in order to solve the above problems, that is, in order to maintain a sufficiently low air permeability and to increase the flexibility of the cloth, a method of making the single yarn fineness of the fibers constituting the cloth smaller is considered. Have been proposed in fact. For example, Japanese Unexamined Patent Publication No. 64-41438 proposes an air bag base fabric made of fibers having a single yarn fineness of 3 d or less, with an emphasis on foldability. Further, in Japanese Unexamined Patent Publication (Kokai) No. 4-2835, an uncoated airbag base fabric made of polyethylene terephthalate has a breathability of 0.5 cc / sec / cm ² or less, based on the features that it is lightweight and thin.
Burst strength above 0 psi, tensile strength of 300 lbs, 4
Woven fabrics having a trapezoidal piece tear strength of 0 pounds have been proposed. Further, in JP-A-4-214437, 4 dtex or less of polyethylene terephthalate,
An uncoated cloth having a total fineness of 250 to 400 dtex has been proposed.

However, if the single yarn fineness is reduced,
Generally, there arises a problem that fuzz and yarn breakage are likely to occur during spinning and weaving. Particularly in the field of airbags, from the viewpoint of cost, gluing and twisting are not performed during weaving, so the above problems cause a great deal of trouble.

If a single yarn breaks due to the rubbing of the yarn and the loom during weaving, the mechanical strength and air permeability of the final fabric may be impaired, which is not preferable. Total fineness 220D
As described above, weaving a filament having a fineness finer than that of a filament constituting a cloth for clothing at a high density until almost no gas permeates has been required for the first time in the advent of an airbag not coated with a resin. It is a thing. However, in the above publication,
Although a solution has been shown in terms of breathability, flexibility, compactness, etc., there is almost no mention of a solution to this fluff or yarn breakage.

On the other hand, in Japanese Laid-Open Patent Publication No. 3-279441, a thick yarn woven fabric is used in which a plurality of warp yarn beams are aligned and tension is applied during weaving, and the weaving density is high and the number of yarns is large. Although a method of weaving a wide woven fabric made of warp threads has been proposed, this method does not attempt to reduce fluff and yarn breakage.

Further, as a proposal for reducing fluff and yarn breakage at the raw yarn stage, for example, Japanese Patent Laid-Open No. 4-1
As disclosed in Japanese Patent No. 94048, an improvement method by controlling the atmosphere under the spinneret at the time of spinning has been proposed. According to this method, the atmosphere under the spinneret is surely controlled to improve the uniformity of the yarn. Although it can be increased, it cannot reduce single yarn breakage during weaving, and the problem is that as the single yarn becomes thinner, single yarn breakage occurs during weaving even if there is no fluff during winding. Was left.

Moreover, the above-mentioned Japanese Patent Laid-Open No. 4-194048 does not describe fluff and pinholes in the base cloth, and there is nothing to do with the decrease in the physical properties of the necessary characteristics such as cloth strength and gas permeability due to the above causes. The reality is that no attention is paid.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems in the prior art, and to provide a non-coated base fabric for an air bag with not only mechanical properties but also low gas permeability. (EN) Provided is a base fabric for an airbag, which has excellent flexibility, has less fluff and yarn breakage during weaving, and has no defects.

[0014]

In order to achieve the above-mentioned object, the airbag base fabric of the present invention is an airbag base fabric whose surface is not coated with resin, and has a total fineness of 220D.
Or more and less than 450 D, single yarn fineness of 0.6 d or more and less than 3 d, strength of 8.0 g / d or more, elongation of 12.0% or more, entanglement degree of 20
The above-mentioned substantially non-twisted multifilament is used, and the cover factor K represented by the following formula of the fabric is 2
It is characterized by being 000 or more. K = N _W × D _W ^0.5 + N _F × D _F ^0.5 where N _W : warp yarn density (books / inch), D _W : warp yarn fineness (denier), N _F : weft yarn density (books / inch), _DF : Weft yarn fineness (denier).

The air bag base fabric of the present invention comprises 15
Dry heat shrinkage at 0 ° C for 30 minutes is 5.0% or more 1
A multifilament having a maximum value of heat shrinkage stress of 2.0% or less and 0.20 g / d or more is used.

The airbag base fabric of the present invention is characterized in that the polymer constituting the multifilament is polyester.

Further, the airbag base fabric of the present invention is characterized by having the following mechanical properties and flexibility. Tensile strength ≧ 170 kg / 3.0 cm Tear strength ≧ 18 kg / 2.54 cm Flexibility (cantilever method) ≦ 70 mm Gas permeation amount at pressure drop of 1.27 cm ≦ 1.0
cm ³ / sec / cm ²

[0018]

The present invention will be described in detail below.

The greatest feature of the present invention is that, as a multifilament that constitutes the base fabric of an airbag, filaments having a specific range of strength, elongation, total fineness and single yarn fineness are highly entangled. . As a result, the performance required for an air bag base fabric, such as breathability, lightness, and flexibility, is satisfied, and fluff and yarn breakage during weaving can be significantly reduced. It is possible to produce a fabric of stable quality without holes.

The airbag base fabric of the present invention is required to have a cover factor K of 2000 or more in terms of lightness and flexibility, with respect to the base fabric used without being coated with resin. If the cover factor K is less than 2000, the air permeability is high, and a satisfactory expansion cannot be achieved.
The mechanical strength of the cloth becomes weak.

The filaments constituting the airbag base fabric of the present invention are required to have a high degree of entanglement, and the degree of entanglement is required to be 20 or more, more preferably 25 or more, still more preferably 30 or more. is there. When the degree of entanglement is less than 20, in the case of the filament of the present invention, since the single yarn is thin as described later, fluff and yarn breakage during weaving occur,
This is not preferable because it leads to defects such as a reduction in ventilation amount due to fluff in the cloth and a decrease in mechanical properties such as tensile strength.

Although yarns having a high degree of entanglement have been heretofore known, there has never been an idea that the degree of entanglement is particularly important in a yarn having a fine single yarn fineness of less than 3d as described later. Is. Especially in the field of airbags, weaving without twisting without twisting,
In the case of fineness, high entanglement becomes more important because yarn breakage and fluffing easily occur.

In the present invention, substantially twist-free means that a twisting step is not particularly performed as a step,
Twisting of the degree of untwisting that occurs during thread removal from a bobbin or cheese is considered to be substantially untwisted. Specifically, a twist of 10 T / m or less is considered to be substantially non-twisted.

The filaments constituting the airbag base fabric of the present invention have a total fineness of 220D or more and 450D or more.
It is necessary to be less than 1, more preferably 270D or more and less than 400D, single yarn fineness of 0.6d or more and less than 3d, and more preferably 0.8d or more and less than 2.2d. If the total fineness is 450 D or more when the density is high enough to maintain a sufficiently low air permeability without coating with a resin, the thickness of the fabric becomes thick, and flexibility and lightness are impaired, which is not preferable. . On the other hand, if the total fineness is 220 D or less, the mechanical strength of the cloth is weak no matter how high the density is woven, and the cloth is ruptured during expansion, which is not preferable. On the other hand, if the single yarn fineness is thicker than 3d, the flexibility is not improved so much even if the total fineness is suppressed, and if it is as thin as 0.6d or less, stable spinning is difficult with ordinary direct spinning, and sufficient entanglement occurs. It is not preferable because it cannot be applied.

Further, the filament constituting the airbag base fabric of the present invention has a strength of 8.0 g / d or more, preferably 8.5 to 10.5 g / d, and an elongation of 12.0% or more, more preferably. Is 14.0% or more of multifilament. In the above-mentioned fineness constitution, in order to satisfy the mechanical properties required as the airbag base fabric, particularly the impact strength, the tear strength and the burst strength, the above-mentioned strength / elongation property is necessary. It is not preferable because the mechanical properties are not satisfied.

Furthermore, the filament constituting the airbag base fabric of the present invention has a dry heat shrinkage ratio of not less than 5.0% and not more than 12.0% at 150 ° C. for 30 minutes and a maximum value of heat shrinkage stress of 0. It is more preferably at least 30 g / d. When the maximum value of dry heat shrinkage or heat shrinkage stress is in the above range, when scouring, heat setting or calendering is performed after fabric production, the fabric is slightly shrunk without impairing the flexibility of the fabric, and the air permeability is improved. It will be lower.

Next, a method for producing the multifilament used for the airbag base fabric according to the present invention will be described below.

As the filaments constituting the airbag base fabric in the present invention, polyesters such as polyethylene terephthalate and polybutylene terephthalate,
Nylon 6, Nylon 66, Nylon 46, Nylon 1
Known polymers such as polyamides such as 2 can be used.

Then, as described above, the single yarn fineness is 0.6.
Among them, polyesters typified by polyethylene terephthalate are more preferably used in the point that a fine fiber yarn having a length of d or more and less than 3d can be easily produced, and in terms of dimensional stability due to low hygroscopicity.

It should be noted that the polymer to be used may contain a copolymerization component for the purpose of enhancing the spinnability, etc. within a range that does not impair the properties thereof. For example, in the case of polyethylene terephthalate, copolymerization of 5-sodium sulfoisophthalic acid at a ratio of 10 mol% or less may be mentioned for the purpose of enhancing the spinnability and flexibility, but the invention is not limited thereto.

Further, in order to satisfy the above physical properties,
Usually, a polymer having a high degree of polymerization is used. In the case of polyethylene terephthalate, the intrinsic viscosity is 0.8 or more, and in the case of polyamide such as nylon 66, the relative viscosity of sulfuric acid is 2.8.
The above polymers are preferable.

The above polymer is spun from the spinneret by the usual melt spinning method. At this time, in order to prevent the polymer from deteriorating due to heat, the shorter the residence time of the polymer in the spinning machine is, the more preferable it is, usually 10 minutes or less, preferably 1 to 5 minutes or less. The spinning temperature is in the range of 285 ° C to 315 ° C, the length of 10 to 100 cm immediately below the spinneret, and 200 ° C.
A heating cylinder whose temperature is controlled to ˜350 ° C. is used, and the discharge yarn is passed through the heating cylinder. The length and temperature conditions of the heating cylinder can be optimized depending on the fineness of the obtained yarn and the number of filaments. The heating cylinder is necessary for delaying the solidification of the molten polymer and developing high strength.

In order to prevent thermal deterioration at high temperature,
It does not matter at all if the atmosphere in the heating cylinder is sealed with a high temperature inert gas as needed.

The spun yarn is passed through the above-mentioned high temperature atmosphere, cooled and solidified with cold air, and then an oil agent is applied thereto,
It is taken up by a take-up roll that controls the spinning speed.

The unstretched yarn taken up by the take-up roll is usually continuously stretched, but it is also possible to wind it once and then stretch it in another step. The spinning speed is usually 200
The stretching is carried out at 0 m / min or less, and the stretching is carried out by a conventional thermal stretching. Stretching is preferably performed in another stage or more in two or more stages, and the stretch ratio varies depending on the birefringence of the unstretched yarn, the stretching temperature, the stretching ratio distribution in multistage stretching, and the like.
It is 6.0 times, preferably 2.0 to 5.5 times.

Next, the drawn yarn is heat-fixed, and the dry heat shrinkage ratio and the maximum value of the heat-shrinkage stress in the present invention are set to desired values by changing the tension and temperature at the time of heat setting. You can

Further, the running yarn can be entangled in the drawing process and the heat setting process. For the entanglement, a known method such as air entanglement can be adopted. For example, in the case of air entanglement, the desired entanglement degree can be achieved by appropriately changing the air pressure according to the fineness and tension of the yarn to be used.

By the above method, a multifilament having a total fineness of 220 D or more and less than 450 D, a single yarn fineness of 0.6 d or more and less than 3 d, a strength of 8.0 g / d or more, an elongation of 12.0% or more, and an entanglement degree of 20 or more is obtained. To be Furthermore, by controlling the tension and temperature in heat setting,
Dry heat shrinkage of the multifilament is 5.0% or more 1
The maximum value of the heat shrinkage stress can be set to 2.0% or less and to 0.20 g / d or more.

In order to produce a base fabric for an airbag using the above-mentioned filaments, the obtained filaments can be used as they are for warp yarns and weft yarns and weaved by a usual method. At this time, there is no particular need for twisting or sizing. The texture is not limited to plain weave, diagonal weave, etc., but plain weave is preferable because of ease of production. As described above, the weave density is such that the cover factor is 2000 or more,
It may be set according to the filament fineness, and an isotropic woven fabric is preferable from the viewpoint of overall characteristics as a base fabric for an airbag.

The obtained air bag base cloth has a tensile strength of 170 kg / 3 cm or more, a tear strength of 18 kg / 2.54 cm or more, a cantilever method softness evaluation of 70 mm or less, and a pressure drop of 1.27 cm. The gas permeation amount in (1) is 1.0 cm ³ / sec / cm ² or less, and low air permeability and flexibility are combined, and there is little fluff, and an air bag base fabric excellent in process passability is obtained.

A base cloth satisfying such conditions is
The burst strength is also 45 kg / cm ² or more.

The airbag base fabric of the present invention may be subjected to scouring, heat setting, and calendering on one or both sides by a known method, if necessary, within a range that does not impair the characteristics of the present invention. It doesn't matter. Rather, in the base fabric of the present invention, when the raw yarns constituting the base fabric have a predetermined dry pickup and heat shrinkage stress, by drying after scouring, heat setting or calendering as described above, The cloth shrinks to the extent that it does not become hard, and the breathability is further suppressed, which is preferable.

[0043]

EXAMPLES The present invention will be described in detail below with reference to Examples, but the physical properties in the text or Examples were measured as follows.

(1) Intrinsic viscosity IV: Using an Ostwald viscometer, to 100 ml of orthochlorophenol,
The relative viscosity ηr of the solution in which 3 g of the sample was dissolved was measured at 25 ° C., and IV was calculated by the following approximate expression. IV = 0.0242 ηr + 0.2634 where ηr = (t × d) / (t ₀ × d ₀ ), t: drop time of solution (sec), t ₀ : drop time of orthochlorphenol (sec), d: Solution density (g / cc), d ₀ : Orthochlorophenol density (g / cc)

(2) Degree of entanglement: JISL-1013 (19)
92).

(3) Thickness: Measured according to JIS-L-1096.

(4) Aeration rate: JIS-L-1096 (A
Method) and the amount of passing air is cc / cm ² / sec
Indicated by.

(5) Bending resistance: JIS-L-1096 (4
5 ° cantilever method).

(6) Tensile strength of base cloth: JIS-K-
According to 6328 (strip method), measurement was performed with a sample width of 3 cm. The results are shown as the average value of the value in the fabric vertical direction and the value in the horizontal direction.

(7) Tear strength: JIS-K-632
The sample width was measured at 2.54 cm according to 8 (Travezoid method). The results are shown as the average value of the value in the fabric vertical direction and the value in the horizontal direction.

(8) Bursting strength: JIS-L-1018A
It is a value measured according to the method (Mullen method).

(9) Dry heat shrinkage ratio: JIS-L-1013
It measured according to the B method. The processing condition was 150 ° C. for 30 minutes.

(10) Heat shrinkage stress: 1/2 of the fineness of the sample
The sample was fixed with an initial load of 0 applied, and the stress generated while the sample was heated was measured using a heating furnace. The maximum value of the measured stress was taken as the value. Sample length is 25 cm, temperature rise is 1
It was performed at 10 ° C / min up to 50 ° C, and at 10 ° C / min for 150 years or more.

Example 1 A polyethylene terephthalate chip having IV = 1.0 was spun by a conventional melt spinning method using a spinneret having 144 holes. At this time, the spinning temperature was 300 ° C., a heating cylinder having a length of 300 mm and a temperature of 300 ° C. was used immediately below the spinneret, and the spinning speed was 500 m / min. The spun yarn is continuously drawn and heat-treated at a temperature of 210 ° C. by a factor of 5.4 without being wound up, and then subjected to a relaxation treatment at a relaxation rate of 3.0% while being air-entangled, and a drawn yarn of 420D and 144 filaments. Got The physical properties of the obtained filament are
Single yarn fineness is 2.92d, strength 8.8g / d, elongation 1
The degree of confounding was 4.2% and 30.

Next, the above filaments are used for warp yarns and weft yarns, and weave density warp 55 yarns / inch, weft 52 yarns /
A plain weave was produced.

Example 2 The same as Example 1 except that a spinneret having 90 holes was used and the total discharge amount was changed so that the single yarn fineness of the drawn yarn obtained was 2.9 denier, which was almost the same as in Example 1. And total fineness 2
A 50D, 90 filament drawn yarn was obtained. The physical properties of the obtained filament were a single yarn fineness of 2.78 d, a strength of 9.0 g / d, an elongation of 14.0%, and an entanglement degree of 36.

Next, the above filaments are used for warp yarns and weft yarns, and weave density warp 70 yarns / inch, weft 66 yarns /
A plain weave was produced.

Example 3 Spinning was performed under the same conditions as in Example 2 except that a spinneret having 288 holes was used to obtain a drawn yarn having a total fineness of 260D and 288 filaments. The physical properties of the obtained filament are single yarn fineness 0.90d, strength 8.5g / d,
The elongation was 13.5% and the degree of confounding was 38.

Then, as in Example 2, the above filaments were used for warp yarns and weft yarns, and weave density 70 warp /
A plain weave of 66 inches and 16 inches wide was prepared.

Comparative Example 1 In Example 1, a spinneret having 72 holes was used and spinning was performed so that the total fineness was 144D. The physical properties of the obtained filament are a single yarn fineness of 2.00 d and a strength of 9.
It was 0 g / d, the elongation was 14.1%, and the degree of entanglement was 28.

Next, the above filaments are used for warp yarns and weft yarns, and weave density warp 86 yarns / inch, weft 85 yarns /
A plain weave was produced.

Comparative Example 2 In Example 1, a spinneret with 180 holes was used and spinning was carried out so that the total fineness was 500D. The physical properties of the obtained filament were a single yarn fineness of 2.78 d, a strength of 8.7 g / d, an elongation of 14.1% and an entanglement degree of 28.

Next, the above filaments are used for warp yarns and weft yarns, and weave density warp 50 / inch, width 49 /
A plain weave was produced.

Comparative Example 3 Spinning was carried out under the same conditions as in Example 1, except that the spinneret with 100 holes was used. The physical properties of the obtained filament were a single yarn fineness of 4.20 d, a strength of 8.6 g / d, an elongation of 13.8% and an entanglement degree of 24.

Next, the above filaments were used for warp yarns and weft yarns, and in the same manner as in Example 1, 55 woven density warp /
A plain weave of 52 inches per inch / inch was prepared.

Comparative Example 4 For the purpose of finally obtaining a multifilament having a total fineness of 300 D, a single yarn fineness of 0.52 d and a filament number of 566 by mixing two fibers, the number of holes is 28 in Example 1.
Using the spinneret of No. 8, spinning was performed so that the total fineness was 150D. However, at this time, single yarn breakage frequently occurred due to yarn fluctuation in the heating cylinder, and winding was difficult.

Comparative Example 5 Spinning was carried out by changing the intrinsic viscosity of the polymer used in Example 1 to 0.6. At this time, the total draw ratio was 4.0 times. The physical properties of the obtained filament are
The single yarn fineness was 2.92 d, the strength was 5.0 g / d, the elongation was 9.8%, and the entanglement degree was 30.

Then, the above filaments were used for warp yarns and weft yarns, and in the same manner as in Example 1, 55 woven density warp /
A plain weave of 52 inches per inch / inch was prepared.

Comparative Example 6 Winding was carried out in Example 1 without using the confounding nozzle. The physical properties of the obtained filament were a single yarn fineness of 2.92 d, a strength of 8.8 g / d, an elongation of 14.2% and an entanglement degree of 10.

Then, the above filaments were used for warp yarns and weft yarns, and in the same manner as in Example 1, weave density warp 55 yarns /
A plain weave of 52 inches per inch / inch was prepared.

Comparative Example 7 A plain weave was prepared by weaving the plain weave in Example 1 such that the weaving density was 44 warps / inch, 42 wefts / inch.

The physical properties of the raw yarns of Examples 1 to 3 and Comparative Examples 1 to 7 are shown in Table 1, and the fabric properties and the process passability during weaving are shown in Table 2.

[0073]

[Table 1]

[0074]

[Table 2]

As is clear from Tables 1 and 2, the samples in this example are excellent in gas permeability, impact resistance, compactness, and process passability, and are well-balanced as an airbag base fabric. You can see that it is getting better.

On the other hand, in Comparative Example 1, the total fineness of the raw yarn is too low, and the tensile strength and tear strength of the cloth are weakened. In Comparative Examples 2 and 3, the total fineness of the raw yarn is too high, or the single yarn fineness of the raw yarn is high, so that the flexibility of the fabric is impaired. In Comparative Example 4, the single yarn fineness of the raw yarn was too low, and fluff and yarn breakage occurred frequently, making it impossible to produce a satisfactory fabric. In Comparative Example 5, the tensile strength of the fabric is low because the strength and elongation of the raw yarn is low. Comparative Example 6
Since there is almost no entanglement, it can be seen that the process passability is extremely poor when weaving the fabric, and that there are many fluffs on the surface of the fabric. Further, in Comparative Example 7, since the cover factor at the time of manufacturing the cloth was low, the amount of gas permeation was remarkably large, and the performance was insufficient for an airbag.

Examples 4 to 6 Under the spinning conditions of Example 1, the temperature and the relaxation rate during drawing and heat treatment were changed, and the raw yarns having the maximum values of dry heat shrinkage and heat shrinkage stress as shown in Table 3 were obtained. Got
A fabric was produced in the same manner as in Example 1 using these raw yarns.

Then, the cloth was subjected to a usual scouring treatment to remove the oily agent, and then subjected to a relaxation heat treatment at 160 ° C. The gas permeability of the fabric after the relaxation heat treatment is also shown in Table 3.
Shown in.

[0079]

[Table 3]

As can be seen from Table 3, when the dry yarn shrinkage ratio shown in the present invention is 5.0% or more and 12.0% or less and the maximum value of the heat shrinkage stress is 0.20 g / d or more is used. In addition, when the fabric is heat-treated, the entire fabric is appropriately contracted, and the amount of gas permeation is further suppressed, which is more preferable as the airbag base fabric.

On the other hand, when the dry heat shrinkage was higher than 12.0%, the heat treatment gave a higher density and suppressed the permeability, but the flexibility of the cloth was slightly impaired. Further, when the dry heat shrinkage was less than 5.0% and the heat shrinkage stress was less than 0.20 g / d, the effect of the heat treatment applied to the fabric was hardly seen.

[0082]

EFFECTS OF THE INVENTION The airbag fabric according to the present invention not coated with resin has a total fineness of 220 D or more and less than 450 D, a single yarn fineness of 0.6 d or more and less than 3 d, and a strength of 8.0 g / d.
As described above, a multifilament having an elongation of 12.0% or more and an entanglement degree of 20 or more is used, and the cover factor F of the cloth is 2 or less.
When it is 000 or more, it has both low air permeability and flexibility, and has little fluff and excellent process passability.

Claims (4)

[Claims] 1. A base fabric for an airbag, the surface of which is not coated with a resin, having a total fineness of 220 D or more and less than 450 D, a single yarn fineness of 0.6 d or more and less than 3 d, a strength of 8.0 g / d or more, and an elongation of 12.0% or more. A base fabric for an airbag, characterized in that a substantially untwisted multifilament having an entanglement degree of 20 or more is used, and a cover factor K represented by the following formula of the fabric is 2000 or more. K = N _W × D _W ^0.5 + N _F × D _F ^0.5 where N _W : warp yarn density (books / inch), D _W : warp yarn fineness (denier), N _F : weft yarn density (books / inch), _DF : Weft yarn fineness (denier). 2. A multifilament having a dry heat shrinkage ratio of 5.0% or more and 12.0% or less at 150 ° C. for 30 minutes and a maximum value of heat shrinkage stress of 0.20 g / d or more is used. The base fabric for an airbag according to claim 1. 3. The airbag base fabric according to claim 1, wherein the polymer forming the multifilament is polyester. 4. The airbag base fabric according to claim 1, which has the following mechanical properties and flexibility. Tensile strength ≧ 170 kg / 3.0 cm Tear strength ≧ 18 kg / 2.54 cm Flexibility (cantilever method) ≦ 70 mm Gas permeation amount at pressure drop of 1.27 cm ≦ 1.0
cm ³ / sec / cm ²