JP2006291396A - Base cloth for airbag, airbag and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an airbag having excellent inner pressure holding performance by suppressing the mesh opening of a seamed part in the expansion of the airbag. <P>SOLUTION: The base cloth for airbag is made of a woven synthetic fiber fabric having a rip-stop texture. A synthetic resin is attached to at least one surface of the woven fabric having rip-stop texture, the air permeability of the base cloth is essentially zero and the slippage resistance is 200-500 N. The base cloth for airbag is produced by applying a synthetic resin to a woven synthetic fiber fabric having a rip-stop texture by knife coating. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In order to reduce the damage to the occupant during deployment of the airbag, the present invention suppresses the opening of the airbag sewing portion and improves the internal pressure retention performance of the airbag by substantially reducing the air permeability of the base fabric. The present invention relates to an airbag base fabric excellent in flexibility of a base fabric and adhesion between a fabric and a resin, an airbag comprising the same, and a method of manufacturing the airbag.

  In recent years, various airbags have been developed and their effectiveness has been recognized and put into practical use in order to ensure the safety of passengers in the event of accidents in various modes of transportation, especially automobiles. Airbags that protect passengers from impacts at the time of a collision, that is, airbags for front seats (for driver seats and for passenger seats) have become more popular as standard equipment in ordinary passenger cars. On the other hand, a side bag with a built-in seat, and a curtain type side bag that descends onto the side window from the roof side of the vehicle (hereinafter referred to as a curtain bag) have been developed for collisions on the side of the car, that is, for a side collision. More and more cars are installed. These side bags, especially curtain bags, require high airtightness, and some are designed so that passengers are not released outside the vehicle when the vehicle rolls over. The internal pressure is maintained.

  In the airbag provided for such purposes, it is required to increase the airtightness of the base fabric constituting the airbag, and a coating agent excellent in heat resistance, wear resistance, flame retardancy, etc., for example, silicone Rubbers and resins such as rubber, polyurethane and chloroprene are used. In addition, when the occupant is protected by the airbag in the event of a collision, the anti-displacement property of the base fabric, especially at the sewn part where stress is concentrated, is improved so that the airtightness of the airbag is not lowered. Is required. Of these, the most frequently used structure is a coated base fabric with a silicone resin as thin as possible coated on a low-density base fabric with plain weave to reduce the mechanical properties, flexibility, and cost of the bag. It is. When the plain weave structure is used, the mechanical characteristics required for the airbag, particularly a strong structure is obtained. The low density base fabric is effective in terms of flexibility and price. Furthermore, the low coating of the silicone resin provides a structure excellent in airtightness and heat resistance of the airbag.

  For example, as such a structure, the invention described in Patent Document 1 is characterized in that a specific functional compound that improves anti-glare property is attached to at least one side of a woven fabric. A silicon compound is preferred. Various resins are described as binders. In this way, attempts have been made to improve the specific performance of the base fabric by attaching different materials to the woven fabric. In this proposal, adhesion of dissimilar materials to the woven fabric is improved, but the resistance to misalignment is improved, but the resin foam containing the inorganic silicon compound having a large particle size described in this patent penetrates the base fabric with a rotary screen device. However, there are problems that the flexibility of the bag is impaired and that the base fabric has air permeability.

The invention described in Patent Document 2 proposes an air bag base fabric excellent in flexibility that is free from fraying during cutting and sewing, in which a synthetic resin adheres to at least one surface of a ripstop fabric. In this proposal, by applying a woven fabric of a ripstop structure rich in flexibility, the flexibility as an airbag base fabric is good. However, as described in Examples etc., aqueous urethane resin foam dilution Since the liquid is coated with a rotary screen device and the base fabric is breathable, the airtightness of the air bag is inferior, and the air bag for a side collision such as the curtain bag described above cannot be used.
JP 2002-220780 A JP-A-11-293541

  Therefore, in view of the background of such a conventional airbag fabric, the object of the present invention is excellent by using a ripstop fabric and attaching a synthetic resin to the airbag fabric constituting the airbag. An object of the present invention is to provide a base fabric for an air bag having excellent internal pressure holding property that allows flexibility and air permeability to be substantially zero, and excellent adhesion to a resin, and a method for producing the same.

  Another object of the present invention is to provide an airbag that uses the above-described airbag fabric and has excellent internal pressure retention performance by suppressing the opening of the sewing portion when the airbag is deployed.

  The present invention employs the following means in order to solve such problems. That is, the airbag fabric of the present invention is an airbag fabric comprising a synthetic fiber fabric, the fabric being a ripstop fabric, and a synthetic resin on at least one side of the ripstop fabric. Is attached, the air permeability of the base fabric is substantially zero, and the sliding resistance is 200 to 500 N.

  One of the preferable aspects of the airbag fabric of the present invention is that the fineness of the ground yarn constituting the woven fabric of the ripstop structure of the airbag fabric is smaller than the fineness of the ripstop yarn.

  One of the preferable aspects of the airbag fabric of the present invention is that the synthetic resin of the airbag fabric has a film formed on the surface of the fabric, and the peel strength of the fabric is 20 to 100 N / cm.

  The airbag fabric of the present invention can be made into an airbag by sewing or the like.

  The method for producing a base fabric for an air bag according to the present invention is characterized in that a synthetic resin is applied to a synthetic fiber fabric having a ripstop structure by knife coating.

  According to the present invention, in order to reduce damage to the occupant during deployment of the airbag, the opening of the airbag sewing portion can be suppressed, and the air permeability of the base fabric can be made substantially zero. It is possible to provide a base fabric for an air bag having excellent internal pressure holding performance, flexibility of the base fabric, and excellent adhesion between the woven fabric and the resin. That is, according to the present invention, it is possible to further promote the occupant protection system using an airbag.

  In order to alleviate the above-mentioned problem, that is, damage to the occupant during deployment of the airbag, the present invention suppresses the opening of the airbag sewing portion and reduces the air permeability of the base fabric to substantially zero. As a result of intensive investigations on airbag fabrics for use in airbags with excellent retention performance, flexibility of the fabric, and excellent adhesion between fabric and resin, synthetic fabrics are ripstop fabrics. And a synthetic resin is attached to at least one side of the woven fabric of the ripstop structure, the air permeability of the base fabric is substantially zero, and the sliding resistance is 200 to 500 N It has been clarified that a base fabric for airbags solves such a problem at once.

  That is, as a condition, weaving a woven fabric in which the fineness of the ground yarn constituting the woven fabric of the ripstop structure is smaller than the fineness of the ripstop yarn in the weaving process, and at least one side of the woven fabric is a floating knife or roll-on in the finishing process. As a result of performing knife coating, a base fabric for an air bag satisfying such requirements was obtained, and it was successful in solving the above problems.

  As the woven fabric used in the present invention, nylon 6,6, nylon 6, nylon 12, nylon 4,6, and nylon 6 and nylon 6,6 copolymer nylon 6 and polyalkylene glycol, A synthetic fiber fabric composed of polyamide fiber or the like copolymerized with dicarboxylic acid or amine is preferably used. Among these, as the fiber material, nylon 6,6 and nylon 6 are particularly preferably used from the viewpoint of impact resistance, and nylon 6,6 is particularly preferably used from the viewpoint of heat resistance.

  Such fibers may contain various additives usually used for improving the productivity or properties in the production process and processing process of the raw yarn. For example, the fiber can contain a thermal stabilizer, an antioxidant, a light stabilizer, a smoothing agent, an antistatic agent, a plasticizer, a thickener, a pigment, a flame retardant, and the like.

  The fiber constituting the woven fabric used in the present invention is a multifilament, and the multifilament preferably has a total fineness within a range of 150 to 700 dtex from the mechanical characteristics and flexibility of the base fabric. Furthermore, from the viewpoint of flexibility, the total fineness is preferably in the range of 200 to 500 dtex. In addition, the multifilament used in the present invention is preferably in the range of 36 to 192, and the single fiber fineness is in the range of 3 to 8 dtex, from the viewpoint of flexibility by reducing the rigidity of the yarn. Is preferred.

The multifilament constituting the woven fabric used in the present invention has a flat cross section, particularly the ratio of the major axis to the minor axis of the cross section, that is, the ratio between the major axis and the minor axis of the cross section, from the viewpoint of thinness and flexibility of the airbag fabric. The aspect ratio is preferably a flat cross-sectional shape in the range of 2 to 4. That is, when a multifilament whose single fiber has such a flat cross-sectional shape is used, the thickness of the airbag base fabric can be reduced and the storage property can be improved. Such a single fiber having a flat cross-sectional shape has an elliptical cross section, but may have a flat cross-sectional shape other than an elliptical shape as long as the aspect ratio of 2 to 4 is satisfied. For example, a left-right asymmetric type such as a rectangle, a rhombus, and a saddle shape may be used, as well as a left-right asymmetric type, or a combination thereof. Further, with the above as a basic mold, there may be a protrusion, a dent, or a partially hollow portion.
If the warp and weft constituting the fabric constituting the airbag base fabric are multifilaments in which the single fiber is a flat cross-sectional yarn, the flat cross-sectional yarn is a woven yarn constituting the airbag base fabric compared to the round cross-sectional yarn. However, it is preferable because it is easy to spread in the longitudinal direction under tension within a specific range, and depending on the spreading method, a special structure that satisfies the frictional resistance value between the fabrics within a specific range can be obtained.

  The multifilament used in the present invention may be a mixture of other types of multifilaments as long as the effects of the present invention are not hindered. In the woven fabric used in the present invention, the multifilament may be used for both the warp and the weft, and other types of yarns may be interwoven within a range not impeding the effects of the present invention.

The woven fabric structure must have a ripstop structure in view of flexibility and mechanical properties. Since the ripstop fabric has a higher degree of freedom in the woven structure than the plain fabric, the tear strength of the base fabric is increased and the flexibility of the base fabric is improved. Therefore, by improving the flexibility of the base fabric, the package volume is reduced in terms of bag storage, and the bag can be easily folded when stored in a package.
The fineness of the yarn constituting the ripstop fabric is preferably smaller than the lipstop yarn in order to achieve both the flexibility of the ripstop fabric and the adhesion between the fabric and the resin. That is, when applying the surface of the base fabric by knife coating, the knife is pressed against the surface of the base fabric, so that a certain amount of resin penetrates into the gaps between the fibers, thereby improving the adhesion between the fabric and the resin. By making the fineness of the ground yarn smaller than the fineness of the ripstop yarn as in the present invention, the lipstop yarn is pressed by a knife as compared with the ground yarn, so the penetration of the resin is increased and the base fabric has excellent adhesion It becomes. In the woven fabric having the ripstop structure, the warp and the weft may be a ripstop yarn, or one of the warp or the weft may be a ripstop yarn. Further, the weft driving at the intersection of the ripstop portions may be performed by inserting two same mouths or by inserting one same mouth. Usually, a woven fabric having a ripstop structure is formed by arranging two warps and wefts, but a woven fabric woven in the warp direction and the weft direction at intervals of 2 to 20 mm in terms of 470 dtex is preferable.

  The base fabric for an air bag of the present invention requires that at least one surface of the woven fabric is coated with a resin. By covering the fabric with resin, the air blocking property is provided, and when the airbag is deployed at the time of a vehicle collision, the bag is inflated for a certain period of time to further reduce the impact of the occupant. Furthermore, the fabric constituting the airbag fabric can be protected from the high-temperature nitrogen gas generated from the inflator.

  As the resin used in the present invention, a resin having heat resistance, cold resistance and flame retardancy is preferably used. Examples of such resins include silicone resins, polyamide resins, polyurethane resins, and fluororesins. Of these, silicone resins are particularly preferably used. As the silicone resin, dimethyl silicone, methyl vinyl silicone, methylphenyl silicone and fluoro silicone are preferably used. Further, the viscosity of the resin used in the present invention is preferably in the range of 5000 to 40000 cps from the viewpoints of maintaining the resin permeation state, adhesiveness between the woven fabric and the resin, and flexibility of the base fabric. For stable coating in the width direction of the base fabric by knife coating, it is more preferably in the range of 10,000 to 20,000 cps. If the resin viscosity is less than 5000 cps, a large amount of resin penetrates into the fabric, so that a large amount of resin is required to make the air permeability of the base fabric substantially zero, and the weight of the base fabric increases. May adversely affect the rapid deployment of On the other hand, if the resin viscosity is higher than 40000 cps, the resin is less likely to penetrate into the fabric, and the amount of coating increases, resulting in poor adhesion between the fabric and the resin.

  The resin is preferably a resin containing a flame retardant compound. As flame retardant compounds, halogen compounds such as bromine and chlorine, particularly halogenated cycloalkanes, platinum compounds, antimony oxides, copper oxides, titanium oxides, phosphorus compounds, thiourea compounds, carbon and cerium can be used. Of these, halogen compounds, platinum compounds, copper oxide, titanium oxide and carbon are more preferably used.

In the airbag fabric according to the present invention, the amount of the resin attached is preferably in the range of 5 to 40 g / m ² from the viewpoint of occupant restraint and flexibility. If the adhesion amount is less than 5 g / m ² , the resin covering the surface of the fabric cannot be uniformly applied, the air permeability of the base fabric is increased, and there is a possibility that the internal pressure sufficient to restrain the passenger at the time of collision cannot be maintained. On the other hand, when the adhesion amount is larger than 40 g / m ² , the volume of the bag obtained by folding the airbag base fabric increases, and it may not be possible to store the bag in a limited space that is simply built in the airbag cover. The amount of adhesion is particularly preferably in the range of 10 to 30 g / m ² from the balance between passenger restraint and storage. In the present invention, it is important to attach the resin to the fabric by knife coating. That is, it is preferable to perform knife coating on the fabric under a pressure of 5 to 20 N / cm. If the pressure is less than 5 N / cm, the resin cannot penetrate into the woven fabric of the ripstop structure, resulting in poor adhesion. In addition, the surface of the fabric to be coated under a pressure higher than 20 N / cm is rubbed with a knife to reduce the base fabric strength, and the resin penetrates more than necessary into the fabric, so that the base fabric permeability is substantially reduced. In order to achieve zero, the amount of resin increases and the weight of the base fabric increases, which may adversely affect the high-speed deployment of the airbag. Therefore, as described above, the use of a resin having a specific viscosity for the fabric of the ripstop structure of the present invention has a very great effect on the adhesion between the fabric and the resin and the flexibility of the base fabric.

  In the airbag fabric of the present invention, it is preferable that the sliding resistance of the fabric is in the range of 200 to 500 N in order to suppress the opening of the sewing portion in the bag deployment at the time of collision and to improve the internal pressure holding performance. . If the slip resistance is less than 200 N, it cannot withstand a high calorie type inflator that has been introduced recently. Specifically, for example, even if it can withstand a 190 kPa inflator for a driver's seat, in a high calorie type inflator such as 230 kPa, the perforation of the outer periphery sewing portion constituting the airbag becomes remarkable, and the bag internal pressure is increased. Not only will this cause a decrease, but hot air may leak from the holes in the sewing area, causing occupant damage. On the other hand, if it is larger than 500 N, it is necessary to make the base fabric rigid, which causes a problem in terms of flexibility. Here, the sliding resistance was measured by ASTM D6479.

  The base fabric for airbags of the present invention preferably has a thickness in the range of 0.2 to 0.4 mm. If the thickness of the base fabric is in such a range, the balance between the base fabric strength and the storage property is balanced. I can take it. The thickness of the base fabric is more preferably in the range of 0.2 to 0.3 mm.

  The base fabric for an airbag of the present invention preferably has a peel strength of the base fabric in the range of 40 to 100N. In order to make the peel strength within the above range, it is necessary to infiltrate the resin to be attached to the inside of the fabric, and it is preferable to apply a floating knife or roll-on knife coating to the fabric of a ripstop structure having a high degree of freedom of yarn. . Further, it is more preferable that the fineness of the ground yarn and the lip yarn is configured as described above so that the resin can easily enter the fabric.

  The air bag base fabric of the present invention preferably has an air permeability of less than 0.1 in order to restrain an occupant during a collision. Furthermore, it is preferable that the air permeability is substantially zero in that the base fabric is inflated for a certain period of time with respect to the vehicle rollover due to a side collision or the like.

  In the method for producing a base fabric for an air bag of the present invention, it is necessary to apply a synthetic resin to a synthetic fiber fabric having a ripstop structure by a floating knife or roll-on knife coating. By applying such a manufacturing method, the synthetic resin can be infiltrated into the fabric without impairing the flexibility of the fabric of the ripstop structure. An excellent airbag fabric can be manufactured. In addition, as the heat treatment, it is preferable to apply a heat treatment under the condition of 50 to 200 ° C. after applying the synthetic resin in order to prevent deterioration of the base fabric, and it is more preferable to perform the heat treatment under a temperature condition of 100 to 180 ° C. Moreover, you may perform a two-step process as needed. The synthetic resin can be applied to the woven fabric either after the raw machine, after scouring, after drying, or after heat setting.

  As a loom used in the weaving process, a water jet room, an air jet room, a rapier room, or the like is used. In particular, in order to increase productivity, a water jet loom that is relatively easy to weave at high speed is preferably used.

  Further, the airbag fabric of the present invention can be used for a driver's seat, a passenger seat, a rear seat, a side airbag, and the like. In particular, it is preferably used as a side bag with a built-in seat for side collision, which requires a higher internal pressure holding performance, and a curtain type side bag that descends from the roof side of the vehicle onto the side window.

  The features of the airbag base fabric and airbag according to the present invention are to reduce damage to the occupant during deployment of the airbag, thereby suppressing the opening of the airbag sewing portion and substantially reducing the air permeability of the base fabric. Therefore, the air bag has excellent internal pressure holding performance, flexibility of the base fabric, and excellent adhesion between the fabric and the resin.

  Next, the present invention will be described in more detail with reference to examples. In addition, various evaluation in an Example was performed in accordance with the following method.

  Thickness: The thickness was measured based on JIS K6328-00.

Fabric weight: The fabric weight was measured based on JIS K6328-00.
Tensile strength: Based on JIS K6328-00 (5.3. 5), the breaking strength when the fabric width was 3 cm, the tension gripping interval was 15 cm, and the tensile speed was 200 mm / min was measured.

  Breaking elongation: The breaking elongation was measured based on JIS K6328-00 (5.3.5).

  Tear strength: Tear strength was measured based on JIS K6328-00 (5.3.6).

  Sliding resistance: Based on ASTM D6479-2002, the maximum strength was measured when a 50 mm × 300 mm fabric sample was pulled at a pulling distance of 200 mm and a pulling speed of 200 mm / min.

  Peel strength: in accordance with JIS K6328-00 (5.3.7), pasted with an adhesive (SE960 made by Toray Dow Corning Silicone) so that the total thickness is 2 mm, then left at 20 ° C. × 65% for 3 days The peel strength when a 2 cm wide sample was pulled at a speed of 50 mm / min was measured.

  Combustibility: Combustion rate was measured by FMVSS302.

  Air permeability of base fabric: Fluid (air) was adjusted to a pressure of 19.6 kPa and flowed, and the flow rate of air passing at that time was measured.

  Bending softness: Bending softness was measured based on JIS L1096-00 (6.19.1).

Example 1
Total fineness 350 dtex, 72 filaments, strength 8.5 cN / dtex, elongation 23.5%, filament yarn made of non-twisted nylon 6.6 fibers as the ground yarn, total fineness 470 dtex, 72 filaments, strength 8.6 cN / Using filament yarn made of non-twisted nylon 6/6 fiber with dtex, elongation of 24.0% as ripstop yarn, wetting the ripstop portion into the same mouth in the water jet loom, warp yarn And a weft density of 59 yarns / 2.54 cm, and a ripstop texture with a ripstop spacing of 1.5 cm. Next, a solventless silicone resin solution having a viscosity of 12 Pa · s (12,000 cP) was coated on the woven fabric with a floating knife coater, followed by vulcanization at a temperature of 190 ° C. for 2 minutes to adhere the resin. An airbag base fabric having an amount of 30 g / m ² was obtained. The characteristics of the airbag fabric thus obtained are shown in Table 1. This airbag fabric was excellent in anti-missing property (sliding resistance) and adhesiveness (peeling strength), and was excellent in flexibility and airtightness with zero air permeability.

(Comparative Example 1)
Filament yarn made of nylon 6/6 fiber with untwisted nylon 6.6 fiber is used for ground yarn and ripstop yarn with total fineness 350dtex, 72 filaments, strength 8.5cN / dtex, elongation 23.5%, in water jet loom, A woven fabric having a ripstop structure in which the weft-driving of the ripstop portion was put into the same two mouths, the weft density of the warp and the weft was 59 / 2.54 cm, and the lipstop interval was 1.5 cm. Next, after coating the woven fabric with a water-based silicone resin solution using a rotary screen device, the fabric is vulcanized at a temperature of 160 ° C. for 2 minutes, and the amount of the resin adhered becomes 30 g / m ^2. I got a cloth. The characteristics of the airbag fabric thus obtained are shown in Table 1. This base fabric for airbags had no problem with respect to flexibility and airtightness, but was inferior in anti-alignment and adhesiveness.

(Comparative Example 2)
The woven fabric obtained in Example 1 was subjected to a scouring set treatment to obtain a non-coated base fabric. The characteristics of the airbag fabric thus obtained are shown in Table 1. This airbag base fabric had no problem with respect to flexibility and anti-disengagement, but was inferior in airtightness and adhesiveness.

(Example 2)
Total fineness 350 dtex, 72 filaments, strength 8.5 cN / dtex, elongation 23.5%, filament yarn made of non-twisted nylon 6.6 fibers as the ground yarn, total fineness 470 dtex, 72 filaments, strength 8.6 cN / Using filament yarn made of non-twisted nylon 6/6 fiber with dtex, elongation of 24.0% as ripstop yarn, wetting the ripstop portion into the same mouth in the water jet loom, warp yarn And a weft density of 53 yarns / 2.54 cm, and a ripstop texture with a lipstop interval of 2 cm was obtained. Next, a solventless silicone resin solution having a viscosity of 11 Pa · s (11,000 cP) was coated on the woven fabric with a floating knife coater, followed by vulcanization treatment at 190 ° C. for 2 minutes to adhere the resin. An airbag base fabric having an amount of 25 g / m ² was obtained. The characteristics of the airbag fabric thus obtained are shown in Table 1. This airbag fabric was excellent in anti-missing property (sliding resistance) and adhesiveness (peeling strength), and was excellent in flexibility and airtightness with zero air permeability.

(Comparative Example 3)
In the woven fabric obtained in Example 2, a water-based polyester urethane resin was adjusted to a solid content of 25% by weight and an anionic foaming agent of 1.5% by weight. After coating with a rotary screen coater, a heat treatment was performed at a temperature of 130 ° C. for 2 minutes to obtain a base fabric for an air bag having a resin adhesion amount of 18 g / m ² . The characteristics of the airbag fabric thus obtained are shown in Table 1. This base fabric for airbags had no problem with respect to flexibility, adhesiveness, and misalignment, but was inferior in airtightness.

(Comparative Example 4)
Using filament yarns consisting of nylon 6/6 fibers with a total fineness of 350 dtex, 72 filaments, strength of 8.5 cN / dtex, elongation of 23.5%, untwisted nylon, weft and weft weave density Both obtained 53 / 2.54 cm plain texture fabric. Next, after coating the woven fabric with a water-based silicone resin solution using a rotary screen device, the fabric is vulcanized for 2 minutes at a temperature of 190 ° C., and the amount of the resin adhered becomes 29 g / m ^2. Got. The characteristics of the airbag fabric thus obtained are shown in Table 1. This airbag fabric was excellent in anti-missing property (sliding resistance) and adhesiveness (peeling strength), and was excellent in flexibility and airtightness with zero air permeability. The characteristics of the airbag fabric thus obtained are shown in Table 1. This base fabric for airbags had no problem with respect to flexibility, adhesiveness, and airtightness, but was inferior in anti- misalignment.

The features of the airbag base fabric and airbag according to the present invention are to reduce damage to the occupant during deployment of the airbag, thereby suppressing the opening of the airbag sewing portion and substantially reducing the air permeability of the base fabric. As a result, the air bag has excellent internal pressure retention performance, flexibility of the base fabric, and excellent adhesion between the fabric and the resin. Therefore, the airbag fabric of the present invention can be suitably used for driver seats, passenger seats, rear seats, side airbags, and the like.

Claims (5)

  A base fabric for an airbag made of a synthetic fiber fabric, wherein the fabric is a fabric of a ripstop structure, and a synthetic resin is attached to at least one surface of the fabric of the ripstop structure, and the air permeability of the base fabric Is substantially zero, and the slip resistance is 200 to 500 N.   The base fabric for an air bag according to claim 1, wherein the fineness of the ground yarn constituting the fabric of the ripstop structure is smaller than the fineness of the ripstop yarn.   The base fabric for an air bag according to claim 1 or 2, wherein the synthetic resin has a film formed on the surface of the fabric, and the peel strength of the base fabric is 40 to 100 N / cm.   The airbag using the base fabric for airbags in any one of Claims 1-3.   A method for producing a base fabric for an airbag, comprising applying a synthetic resin to a synthetic fiber fabric having a ripstop structure by knife coating.