Airbag base fabric and airbag, and methods for manufacturing same

Abstract

The present invention provides: an airbag base fabric that constitutes an airbag cushion that is flexible, lightweight, highly packable, exhibits high energy efficiency during airbag inflation, and resists seam rupture even under high pressure; an airbag base fabric that constitutes an airbag cushion with strong abrasion resistance and low environmental impact; and a method for manufacturing the same. This airbag base fabric is an airbag base fabric in which a woven fabric composed of multifilament yarns serving as both the warp and weft is coated with a film on at least one side thereof, and is characterized in that the bias / parallel tensile strength ratio of the airbag base fabric is 0.2 to 0.6.

Description

Airbag fabric, airbag, and manufacturing method thereof

[0001] The present invention relates to an airbag base fabric constituting an airbag cushion used in an airbag device for mitigating impact on the human body in a collision accident such as a car, and a manufacturing method thereof.

[0002] The installation of airbag devices in vehicles such as automobiles as devices for absorbing impacts to the human body in vehicle collisions has been increasing. Airbag devices inflate with gas during a collision to absorb and mitigate impacts to the human body. In addition to driver's and passenger's seat airbags, various airbag devices, such as curtain airbags, side airbags, knee airbags, and rear airbags, have been put into practical use for protecting occupants. Furthermore, for pedestrian protection, airbag devices (pedestrian airbags) consisting of an airbag cushion that inflates outside the vehicle passenger compartment and far-side airbag devices consisting of an airbag cushion that restricts movement of an occupant seated in the opposite direction to the impact side in the event of a side collision on the far side of the vehicle seat have also been proposed.

[0003] The airbag cushions of these airbag devices are normally folded up and stored. When a sensor detects the impact of an accident and the airbag cushion deploys, the gas generated by the inflator pushes the folded airbag cushion open, breaking through the cover where it is stored and allowing the airbag cushion to pop out. When fully inflated, it will catch the human body.

[0004] In recent years, airbag systems have become larger in size to accommodate a wider range of collision conditions. Meanwhile, storage space has become increasingly limited to expand vehicle interior space, necessitating a more compact airbag storage size (storage capability). In particular, pedestrian airbags and far-side airbags, which have seen an increase in installation rates in recent years, tend to be larger due to the wide range of collision locations. However, they must be stored in locations with limited storage space, such as near the hood or inside the car seat. Examples of wide-ranging collision conditions include the aforementioned collision locations, as well as the need to mitigate impact during collisions for occupants of various body types and postures. Therefore, there is a demand for faster airbag deployment speeds and higher internal airbag pressure (internal pressure) to absorb collision energy. As airbag cushion sizes increase, the volume of the airbag inflation chamber (chamber) tends to increase. Therefore, in order to rapidly increase the internal pressure of a large-capacity airbag, increased inflator output (gas generation) is required. However, increasing inflator output is undesirable because it increases damage to the airbag cushion and increases weight and cost. Therefore, there is a demand for suppressing gas leakage when the airbag is inflated and deployed, for the airbag to inflate sufficiently even with limited inflator output, and for the airbag to maintain a high internal pressure, in other words, for improving the energy efficiency of airbag inflation.

[0005] Furthermore, in order to accommodate a wide range of collision conditions, the shape of the airbag needs to be more complex, which has led to an increase in the number of sewn parts and more complex stitching shapes, and there is a demand for airbags that can absorb high collision energy while maintaining compactness and that are less likely to tear at the sewn parts even under high internal pressure.In addition, as the storage space for airbags becomes smaller and the internal pressure of the airbag increases, the risk of abrasion damage to the cushion by the airbag device cover or vehicle interior parts, etc., has increased, and in recent years, the possibility of cuts on the cushion by glass fragments causing a decrease in the internal pressure of the airbag has also become a problem.

[0006] On the other hand, in recent years, there has been an increasing need to reduce the environmental impact of automotive parts, and there is a demand for airbag cushions that can reduce GHG emissions during manufacturing and that are easily recyclable at the time of disposal. Furthermore, from the perspective of the environmental impact of automobiles when they are driven and the driving distance associated with the shift to electric vehicles, there is an increasing demand for improved fuel economy (or electric power consumption), and there is a strong demand for lighter airbag cushions.

[0007] In order to suppress gas leakage from airbags, the surface of the fabric is usually covered with a coating material, and a silicone-coated base fabric in which the fabric is coated with silicone is commonly used. However, when silicone is coated, problems have arisen such as an increase in the basis weight of the base fabric, an increase in the weight of the airbag, high GHG emissions during production, and a process of separating the silicone from the fabric for recycling. If the amount of silicone coating is reduced, problems arise such as an increase in the amount of gas leakage from the fabric surface and a deterioration in the flammability of the fabric.

[0008] Patent Document 1 below proposes a film-laminated airbag fabric. Because a continuous film covers the woven fabric, there is less gas leakage from the surface of the fabric compared to a silicone-coated fabric, making it easier to increase the pressure inside the airbag (high energy efficiency in airbag inflation). However, compared to a silicone-coated fabric, the fabric is harder, which causes problems with poor airbag cushion storage. Furthermore, thinning the film to soften it can lead to poor adhesion and knead resistance, or if pinholes form due to the heat and pressure generated during thermal lamination, it may not be able to withstand the high pressure of the airbag and may burst.

[0009] Patent Document 2 below proposes an airbag fabric in which at least one side of a woven fabric is coated with a multilayer film having an adhesive layer, and the average value of the slip resistance of the fabric over the course of time is 350 N / 2.5 cm or more. Patent Document 3 also proposes an airbag fabric comprising a woven fabric and a resin layer containing a thermoplastic resin at least in part laminated thereon, and having a slip resistance of 300 N or more measured according to ASTM D 6479-02 (2003). By using a woven fabric with high slip resistance, the opening (mesh misalignment) of the base fabric and sewn parts under high pressure is suppressed, resulting in an airbag cushion with excellent airtightness and pressure resistance. However, the present inventors have recently discovered through their studies that even if the thickness of the film material is reduced to the extent that it can be formed into a film, the base fabric is hard due to the properties of the film material itself and the laminate, and the airbag cushion has poor storage properties.

[0010] Patent Document 4 below proposes an airbag woven / knitted fabric for insertion into an airbag cushion, comprising a woven / knitted fabric substrate at least partially coated or laminated thereto, the woven / knitted fabric substrate having a cover factor of approximately 1900 or less. That is, by providing a film (laminate) or coating on a loosely constructed woven / knitted fabric, which has not previously been used with silicone-coated fabrics, an airbag with extremely low air permeability can be obtained. Furthermore, because the woven / knitted fabric is loosely constructed, an airbag with superior storability can be obtained compared to airbags manufactured using airbag woven / knitted fabrics with a cover factor of 1900 or more can be obtained. However, the document does not describe whether the storability is superior to that of silicone-coated fabrics or how to improve the storability. Furthermore, the document does not describe any method for producing an airbag that can absorb high collision energy or is less likely to tear at the seams even under high internal pressure, or any method for preventing abrasion damage to the cushion caused by the airbag device cover or vehicle interior parts due to increased internal pressure of the airbag.

[0011] Patent Document 1: JP-A-2005-535488 International Publication No. 2021-157725 Japanese Patent Application Laid-Open No. 2008-150754 Patent Document 2: JP-A-2003-527254

[0012] In view of the above-described background technology, the problem to be solved by the present invention is to provide an airbag base fabric that constitutes an airbag cushion that is flexible, lightweight, and easy to store, has good energy efficiency in airbag inflation, and is resistant to seam tearing even under high pressure. Furthermore, it is an object of the present invention to provide an airbag base fabric that constitutes an airbag cushion that is resistant to cushion abrasion and has a low environmental impact.

[0013] In order to solve the above problems, the present inventors have conducted intensive research and experiments, and as a result, have unexpectedly found that the problem can be solved by an airbag fabric having the following characteristics. This has led to the completion of the present invention.

[0014] That is, the present invention is as follows. [1] An airbag fabric in which at least one side of a woven fabric, both of which warp and weft are made of multifilament yarns, is covered with a film, and the bias / parallel tensile strength ratio of the airbag fabric is 0.2 or more and 0.6 or less. [2] The airbag fabric according to [1] above, in which the cover factor (CF) of the woven fabric is 1700 or more and 2000 or less. [3] The high-pressure air permeability of the airbag fabric under a differential pressure of 100 kPa is 0.10 L / cm ２ [4] The airbag fabric according to any one of [1] to [3], wherein the total fineness of the yarns constituting the woven fabric is 200 dtex or more and 900 dtex or less. [5] The airbag fabric according to [4], wherein the single yarn fineness of the yarns constituting the woven fabric is 1 dtex or more and 7 dtex or less. [6] The airbag fabric according to any one of [1] to [5], wherein the thickness of the coating is 1 μm or more and 20 μm or less. [7] The airbag fabric has a basis weight of 100 g / m ２ More than 300g / m ２[8] The airbag fabric according to any one of [1] to [7], wherein the bias tensile strength of the airbag fabric is 300 N / 2 cm or more and 500 N / 2 cm or less. [9] The tear strength characteristic value (T value) of the airbag fabric in the warp and weft directions of the fabric is 1.6 N / (g / m ２ ) or more 5.0N / (g / m ２

[10] The airbag fabric according to any one of [1] to [8], wherein the breaking strength characteristic value (F value) of the airbag fabric in the warp and weft directions of the fabric is 8.0 N / (g / m ２ ) or more 20.0N / (g / m ２

[11] The airbag fabric according to any one of [1] to [9], wherein the slip resistance value (E value) of the airbag fabric in the warp and weft directions of the fabric is 1.0 N / (g / m ２ ) or more 10.0N / (g / m ２) or less.

[12] The airbag fabric according to any one of [1] to

[11] , wherein the bending resistance (S value) of the airbag fabric in the warp and weft directions of the woven fabric is 2.0 N or more and 9.0 N or less.

[13] The airbag fabric according to any one of [1] to

[12] , wherein the thickness of the coating is 1 μm or more and 20 μm or less, and the sum of the cut surface fiber meandering ratios in the warp and weft directions of the woven fabric is 5.0% or more and 12.0% or less.

[14] The airbag fabric according to any one of [1] to

[13] , wherein the cut surface fiber meandering ratios in the warp and weft directions of the woven fabric are 2.0% or more and 7.0% or less.

[15] The airbag fabric according to any one of [1] to

[14] , wherein the sum of the crimp rates in the warp and weft directions of the woven fabric is 5.0% or more and 12.0% or less.

[16] The airbag fabric according to

[15] , wherein the crimp rates in the warp and weft directions of the woven fabric are all 2.0% or more and 7.0% or less.

[17] The airbag fabric according to any one of [1] to

[16] , wherein the cover-single yarn contact ratios in the warp and weft directions of the woven fabric are all 20% or more and 40% or less.

[18] The tear strength characteristic value (T value) of the airbag fabric in the warp and weft directions of the woven fabric is 1.6 N / (g / m ２ ) or more 5.0N / (g / m ２

[19] The airbag fabric according to any one of [1] to

[18] , wherein the tear strength (T value) of the airbag fabric in both warp and weft directions of the woven fabric is 300 N or more and 800 N or less.

[20] An airbag comprising the airbag fabric according to any one of [1] to

[19] .

[21] A method for producing the airbag fabric according to any one of [1] to

[19] , comprising the following steps: a laminating step of adhering a film to at least one surface of the woven fabric while applying tension in the warp and / or weft directions of the woven fabric; and a heat treatment step of heating the obtained film-laminated woven fabric at a temperature of 150°C or more while applying tension in the warp and / or weft directions of the woven fabric.

[22] The method for producing an airbag fabric according to

[21] , wherein the ratio of the tear strength of the woven fabric laminated with the film after the heat treatment step to the tear strength of the woven fabric subjected to the lamination step is 100% or more and 500% or less in both warp and weft directions of the woven fabric.

[23] The method for producing an airbag fabric according to

[21] or

[22] , wherein the ratio of the slip resistance of the woven fabric laminated with the film after the heat treatment step to the slip resistance of the woven fabric subjected to the lamination step is 200% or more and 2000% or less in both warp and weft directions of the woven fabric.

[24] An airbag fabric in which at least one side of a woven fabric, the warp and weft of which are both made of multifilament yarns, is covered with a film, the cover factor (CF) of the woven fabric is 1700 to 2000, the thickness of the covering is 1 μm to 20 μm, and the sum of the cut surface fiber meandering rates in the warp and weft directions of the woven fabric is 5.0% to 12.0%.

[25] An airbag fabric in which at least one side of a woven fabric, the warp and weft of which are both made of multifilament yarns, is covered with a film, the cover factor (CF) of the woven fabric is 1700 to 2000, and the cover-single yarn contact rate in the warp and weft directions of the woven fabric is 20% to 40%.

[26] An airbag fabric in which at least one side of a woven fabric, both of which are made of multifilament warp and weft yarns, is covered with a film, and the tear strength characteristic value (T value) of the airbag fabric in the warp and weft directions of the woven fabric is 1.6 N / (g / m). ２ ) or more 5.0N / (g / m ２ ) The airbag base fabric is as follows.

[0015] If an airbag cushion is produced from the airbag fabric according to the present invention, it will be a flexible, lightweight, and easy-to-store airbag cushion that is energy efficient in expanding the airbag and is less likely to tear at the seams even under high pressure. Furthermore, it will be an airbag cushion that is resistant to abrasion of the cushion and has a low environmental impact, and is particularly suitable for use in pedestrian airbags and far side airbags, which require good storage properties.

[0016] FIG. 1 is a plan view of an airbag used in Examples. FIG. 2 is a schematic diagram of measuring the thickness (mm) of two layers of an airbag fabric and the thickness (mm) of a bent portion. FIG. 3 is a schematic diagram of an airtightness measuring device for evaluating the internal pressure retention (%) of an airbag fabric under 100 kPa. FIG. 4 is a schematic diagram of an airtightness measuring device for evaluating the internal pressure retention (%) of an airbag fabric under 100 kPa. ２) and a schematic diagram of a burst test device for evaluating the burst tear length (mm). A graph showing the relationship between the internal pressure of an airbag and time in a burst test, illustrating a method for calculating the burst absorption momentum. Figure 5(A) shows a case where there is no rising point at which the pressure changes from negative to positive, and Figure 5(B) shows a case where there is a rising point at which the pressure changes from negative to positive. An explanatory diagram of a method for measuring the coating thickness (μm). Figure 6(A) shows a case where a vertical line intersects with the top single yarn, and Figure 6(B) shows a case where a vertical line passes between two single yarns. A schematic diagram illustrating the cutting position of an airbag fabric when measuring the cut surface fiber meandering ratio of the airbag fabric. The A-A' cross section is a cross section cut so that both the diameter yarn and the weft yarn are included in the cut surface, and the B-B' cross section is a cross section cut so that only the diameter yarn is included in the cut surface. Even for fibers with other weaves (such as twill), the cross sections cut according to the above definitions are defined as the A-A' cross section and the B-B' cross section. 10A and 10B are schematic diagrams illustrating the cut surface of an airbag fabric to show a method for measuring the cut surface fiber meandering rate (%) of the airbag fabric. 10B is a schematic diagram illustrating the cutting position of the airbag fabric when measuring the cover-single yarn contact rate of the airbag fabric. The A-A' cross section is a cross section cut so that both the diameter yarn and the weft yarn are included in the cut surface, and the B-B' cross section is a cross section cut so that only the diameter yarn is included in the cut surface. Even for fibers with other weaves (such as twill), the cross sections cut according to the above definitions are defined as the A-A' cross section and the B-B' cross section. 10A is a schematic diagram illustrating the cut surface of an airbag fabric to show a method for measuring the cover-single yarn contact rate (%) of the airbag fabric. 10A and 10B show different degrees of infiltration of the cover into the single yarn bundle.

[0017] The following describes in detail the embodiments of the present invention, but the present invention is not limited to these embodiments and examples, and can be modified as desired without departing from the spirit and scope of the present invention.

[0018] One embodiment of the present invention is an airbag fabric in which at least one side of a fabric composed of warp and weft yarns that are both multifilament yarns is covered with a film, and the bias / parallel tensile strength ratio of the airbag fabric is 0.2 or more and 0.6 or less. This is an airbag fabric.

[0019] The airbag fabric of this embodiment is an airbag fabric in which at least one side of a woven fabric, both warp and weft yarns of which are multifilament yarns, is coated with a resin film. It is preferable that the film is coated by lamination. The film covering the woven fabric is preferably a multilayer film composed of at least two layers, of which the layer that adheres to the woven fabric is called the "adhesive layer," and the layer exposed on the outermost surface of the film surface of the airbag fabric is called the "outer layer." From the viewpoint of recyclability, it is preferable to use a thermoplastic resin for each layer of the single-layer film or multilayer film.

[0020] The multilayer film may have a two-layer structure of adhesive layer / outer layer, in which an adhesive layer and an outer layer are laminated together, a three-layer structure of adhesive layer / intermediate layer / outer layer, or a five-layer structure of adhesive layer / glue layer / intermediate layer / glue layer / outer layer. Furthermore, the multilayer film may further include layers other than those described above. The multilayer film will now be described.

[0021] (Adhesive Layer) The adhesive layer is a layer that melts and softens when exposed to heat from a heating roll during thermal lamination, and adheres to the surface of the fabric. From the viewpoint of adhesiveness and flexibility, the adhesive layer preferably contains a resin having a melting point of 100 to 160°C (referred to herein as "resin A"). The adhesive layer may contain another resin (referred to herein as "resin B") in addition to the resin A. The resin A and the resin B may each be one type or multiple types. The adhesive layer may be composed of only resin A, or may further contain resin B and the additives described below.

[0022] The melting point of the resin A is preferably 100 to 160°C, more preferably 110 to 150°C, and even more preferably 120 to 140°C. By making the melting point 100°C or higher, the adhesive strength with the base fabric can be maintained even in a high-temperature usage environment, and the range of conditions (also known as the process window) such as temperature, pressure, and time during lamination can be widened, resulting in a multilayer film of stable quality. On the other hand, by making the melting point 160°C or lower, the temperature required during lamination is not too high, and heat damage to the fabric and film can be suppressed. The melting point can be measured by the method described in the Examples below.

[0023] When multiple types of resin A are used, the melting points of the resins constituting resin A may be the same or different. When multiple types of resin A are used and there are multiple melting peaks, the melting peak temperature on the higher temperature side of resin A is preferably 100 to 160°C, more preferably 110 to 150°C, and even more preferably 120 to 140°C.

[0024] As the resin A, a polyamide resin is preferred in that changes in properties such as flexibility and adhesiveness are small in response to changes in temperature and humidity in the usage environment. Among these, as the polyamide resin, polyamide copolymer (a-1), dimer acid polyamide (a-2), and thermoplastic polyamide elastomer (a-3) are preferred, and copolymer polyamide (a-1) is more preferred from the viewpoints of flexibility, adhesiveness, internal pressure retention at high pressure, and cost. Examples of the polyamide copolymer (a-1) include copolymer polyamides copolymerized using two or more monomer components known as monomer components constituting aliphatic polyamides (e.g., monomer components constituting polyamide 6, polyamide 66, polyamide 11, and polyamide 12), such as polyamide 6 / 66, polyamide 6 / 12, polyamide 6 / 11, polyamide 6 / 66 / 11, and polyamide 6 / 66 / 12. Examples of the dimer acid polyamide (a-2) include those made from a raw material obtained by dimerizing fatty acids of natural vegetable oils (unsaturated fatty acids having 18 carbon atoms (e.g., oleic acid, linoleic acid, etc.)). Examples of the thermoplastic polyamide elastomer (a-3) include thermoplastic polyamide elastomers (including dimer acid thermoplastic polyamide elastomers) containing a polyether in the soft segment (amorphous phase) and a polyamide component in the hard segment (crystalline phase). Among these, polyamide 6 / 12 is preferred from the viewpoints of particularly excellent flexibility, adhesiveness, and internal pressure retention at high pressure. The viscosity number of the polyamide resin used in the adhesive layer is 50 to 200 ml / g, more preferably 80 to 180 ml / g, and even more preferably 100 to 150 ml / g. A viscosity number of 50 ml / g or more prevents the molten resin from penetrating the woven fabric too much, thereby preventing the airbag fabric from becoming too hard. On the other hand, if the viscosity number is 200 ml / g or less, the adhesive layer penetrates into the single yarns in the surface layer of the woven fabric, and sufficient adhesiveness can be obtained by the anchoring effect. Note that the viscosity number is a value determined in accordance with ISO 307, and is the viscosity number when 0.5 mass % of a polyamide-based resin is dissolved in a 96% aqueous sulfuric acid solution.

[0025] The adhesive layer may contain the resin B in addition to the resin A. In this case, preferred examples of the resin B include acid-modified polyolefins, ionomers, and thermoplastic polyamide elastomers. From the viewpoint of flexibility and adhesiveness in low-temperature environments, the glass transition temperature is preferably 40°C or lower, more preferably 30°C or lower, and even more preferably 20°C or lower. The melting point is preferably in the range of 80 to 160°C. From the viewpoint of adhesiveness, the mass proportion of the resin B in the adhesive layer (100% by mass) is preferably 90% by mass or lower, more preferably 80% by mass or lower, and even more preferably 70% by mass or lower.

[0026] The adhesive layer may contain various additives, such as antiblocking agents, lubricants, crystal nucleating agents, flame retardants, antistatic agents, antioxidants, UV absorbers, light stabilizers, colorants, and fillers, as appropriate, to the extent that practical properties such as adhesiveness are not impaired. Among these, from the viewpoint of further improving the blocking resistance of the adhesive layer, it is preferable to contain an antiblocking agent, a crystal nucleating agent, and / or a lubricant, more preferably an antiblocking agent and / or a crystal nucleating agent, and even more preferably an antiblocking agent and a crystal nucleating agent. Examples of the antiblocking agent include organic particles such as crosslinked polystyrene, crosslinked acrylic (PMMA) resin, and fluorine (PTFE) particles, as well as inorganic particles such as silica particles, kaolin, and calcium carbonate. Examples of the crystal nucleating agent include talc, alumina, kaolin, and high-melting-point polyamides (e.g., polyamides with a melting point above 160°C). Examples of the lubricant include aliphatic amides and metal soaps.

[0027] From the viewpoints of adhesion and blocking resistance, the mass proportion of the resin A (e.g., copolymerized polyamide) relative to 100% by mass of the adhesive layer is preferably 10% by mass or more, more preferably 20% by mass to 100% by mass, and even more preferably 30% by mass to 100% by mass. From the viewpoints of adhesion and blocking resistance, the mass proportion of the additive in the adhesive layer (100% by mass) is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0028] (Outer Layer) The outer layer can be composed of a resin having a melting point higher than that of the adhesive layer, from the viewpoint of preventing sticking to the roll and pinholes by melting during thermal lamination. The melting point of the resin used in the outer layer is preferably 20°C or more higher than that of Resin A, more preferably 25°C or more higher, and even more preferably 30°C or more higher. The melting point of the resin used in the outer layer is determined based on the ease of fusion (sticking) to the heated roll used in the lamination process with the woven fabric. By using a resin with a melting point 20°C or more higher than that of Resin A, fusion to the heated roll is less likely to occur, and stable lamination can be achieved. Note that when multiple types of Resin A are contained in the adhesive layer and / or when multiple types of resins are contained in the outer layer, the melting point refers to the melting peak temperature at the highest temperature among the melting peak temperatures attributable to the multiple resins contained in the layer. Furthermore, since the outer layer becomes the outermost layer, particularly when laminated to a woven fabric, the flexibility of the outer layer affects the flexibility of the laminated base fabric. Therefore, polyamide-based resins and polyester-based resins are preferred from the viewpoint of obtaining an outer layer with excellent properties such as flexibility, resistance to stress generated when folded, airtightness, resistance to sewing needle punctures, strength, flame retardancy, and slipperiness. Examples of the polyamide-based resin include the polyamide copolymers (a-1, a-2, a-3) exemplified as resin A contained in the adhesive layer, and homopolymers such as polyamide 6, polyamide 66, polyamide 11, and polyamide 12. These may be used alone or in a blend of multiple types. Examples of the polyester-based resin include thermoplastic polyester elastomers, such as those using a polyether component in the soft segment (polyether-polyester type) and those using a polyester component in the soft segment (polyester-polyester type).

[0029] (Intermediate Layer) Examples of the intermediate layer include a layer made of a composition obtained by blending one or more of a polyolefin resin such as linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, or polypropylene, an acid-modified polyolefin resin, a polyolefin copolymer resin, a polyolefin thermoplastic elastomer, or an acid-modified polyolefin elastomer, and from the viewpoint of flexibility, it is preferable that the intermediate layer contains a polyolefin copolymer resin and / or a polyolefin thermoplastic elastomer.

[0030] (Glue Layer) The glue layer is a layer for bonding the layers of the multilayer film together, and examples thereof include a layer made of an acid-modified polyolefin resin having a polar functional group, such as acid-modified polyethylene or acid-modified polypropylene, and / or a polyolefin thermoplastic elastomer, and it is desirable to select the glue layer taking into consideration the requirements for heat resistance, etc., in the intended application. The glue layer may be a layer made of only one type of resin, or may be a layer containing multiple types of resins.

[0031] (Film) The thickness of the coating of the airbag fabric of this embodiment can be 1 μm or more and 30 μm or less, preferably 2 to 20 μm, more preferably 3 to 17 μm, even more preferably 4 to 15 μm, and even more preferably 5 to 13 μm. The coating thickness here does not refer to the thickness of the film itself before being laminated to the airbag fabric, but rather to the thickness of the coating portion when coated on the airbag fabric. These ranges are determined by the balance between strength and flexibility, and a film (coating material) with a coating thickness of 1 μm or more can obtain the mechanical properties necessary for an airbag and reduce ventilation from the surface of the fabric. On the other hand, by making the coating thickness 20 μm or less, flexibility is improved, contributing to the compactness of the airbag. By covering a flat airbag fabric with a film so that the thickness of the covering is within the above range, when stress is applied to the fabric during airbag deployment, the stress is propagated by the film (covering material) and the yarns of the fabric move appropriately, effectively dispersing the stress and maintaining the expanded state without breaking. Therefore, more energy can be absorbed during a vehicle collision. That is, energy efficiency can be improved.

[0032] The basis weight of the film (covering material) covering the airbag fabric of this embodiment is 5 g / m ２ 35g / m or more ２ It can be less than 5 to 30 g / m ２ and more preferably 5 to 25 g / m ２ and particularly preferably 5 to 15 g / m ２ The film weight is 5 g / m ２ On the other hand, if the basis weight of the film is 35 g / m or more, good adhesion to the woven fabric and high internal pressure retention can be obtained. ２If the mass fraction of the film is 15% or less, it is possible to prevent the film from penetrating too far into the woven fabric, which would cause the base fabric to become hard or reduce its tear strength. The basis weight of the film is preferably 15% or less, more preferably 10% or less, and even more preferably 7% or less, of the basis weight of the airbag base fabric (composite of film and woven fabric). By setting the mass fraction of the film to 15% or less, it is possible to obtain an airbag cushion material that has high resin strength when remelted and is highly recyclable. On the other hand, if the mass fraction of the film is 2% or more, it is possible to obtain good adhesion to the woven fabric and high internal pressure retention.

[0033] From the viewpoint of recyclability, the film coated on the airbag fabric of this embodiment preferably contains the same type of resin as the woven fabric. When the woven fabric is polyamide, it is preferable that the film contains a polyamide resin in its layer structure, and the ratio of the total basis weight of the one or more polyamide resin layers constituting the film to the basis weight of the film is more preferably 30% or more, even more preferably 50% or more, even more preferably 70% or more, and particularly preferably 100%. When the woven fabric is polyester, it is preferable that the film contains a polyester resin in its layer structure, and the ratio of the total basis weight of the one or more polyester resin layers constituting the film to the basis weight of the film is more preferably 30% or more, even more preferably 50% or more, even more preferably 70% or more, and particularly preferably 100%. By making the film contain the same type of resin as the woven fabric, the compatibility when remelted is high, so the resin strength can be increased, and a highly recyclable airbag cushion material can be obtained.

[0034] (Airbag fabric) The total fineness of the fibers constituting the airbag fabric is preferably 200 dtex or more and 900 dtex or less, more preferably 250 dtex to 750 dtex, and even more preferably 300 dtex to 500 dtex. If the fineness is 200 dtex or more, the strength of the base fabric will not be insufficient, and on the other hand, if the fineness is 900 dtex or less, the deployment speed will not be slowed. In addition, the lower the total fineness, the lower the hardness and basis weight of the base fabric can be kept.

[0035] The single yarn fineness of the fibers constituting the airbag base fabric is preferably 1.0 dtex or more and 7.0 dtex or less, more preferably 2.0 to 4.0 dtex. If it is 1.0 dtex or more, the filament will not be damaged by the sewing needle when sewn, the strength of the sewn portion (the boundary between the inflatable portion and the non-inflatable portion) will not decrease, and destruction will not occur during deployment. On the other hand, if it is 7.0 dtex or less, the air permeability will increase and the deployment speed will not slow down. In addition, the smaller the single yarn fineness, the lower the hardness of the base fabric can be kept. Furthermore, the smaller the single yarn fineness, the less crimp there is in the woven fabric, the flatter the surface, and the better the adhesion to the film. In addition, single yarns having cross-sectional shapes such as flat, triangular, and polygonal such as pentagonal can also be used to flatten the woven fabric. On the other hand, by making the cross-sectional shape of the single yarn approximately circular, the gaps between the single yarns are less likely to vary, the degree of penetration of the resin component of the film into the woven fabric is more likely to be stable, and the tear strength of the base fabric can be increased as well as the scrubbing properties of the base fabric can be improved. The aspect ratio of the cross section of the single yarn (the ratio of the cross-sectional lengths of the major axis and the minor axis) is preferably 1.5 or less, more preferably 1.2 or less, and even more preferably 1.1 or less.

[0036] The cover factor (CF) of the airbag fabric of this embodiment can be 1700 or more and 2000 or less. By setting the cover factor to 2000 or less, the storability required for an airbag can be obtained. The cover factor (CF) is expressed by the following formula: CF = √{(d) × (1.14 / D)} × (2 × W) (where d is the warp and weft average total fineness (dtex) of the constituent yarns, and D is the density of the constituent yarns (g / cm ３), and W is the warp and weft average weave density (counts / inch (2.54 cm)).}. The cover factor of an airbag fabric refers to the cover factor of the woven fabric that constitutes the fabric. A more preferred range of the cover factor is 1700 to 1950, even more preferably 1750 to 1900, and even more preferably 1800 to 1850. If the cover factor is 1700 or higher, the fabric strength and airtightness required for an airbag can be obtained. Furthermore, by setting the cover factor to 1700 or higher, weaving and lamination can be performed without destroying the warp and weft weave structure.

[0037] The weave fineness (WF) of the airbag fabric of this embodiment is preferably 30,000 or more and 50,000 or less, and more preferably 35,000 to 45,000. By setting the weave fineness to 30,000 or more, the fabric strength and airtightness required for an airbag can be obtained. On the other hand, by setting the weave fineness to 50,000 or less, the airbag can be made compact and lightweight. The weave fineness (WF) is expressed by the following formula: WF = {(d) × (1.14 / D)} × (2 × W) {where d is the warp and weft average total fineness (dtex) of the constituent yarns, and D is the density of the constituent yarns (g / cm ３ ), and W is the warp and weft average weave density (counts / inch (2.54 cm)).} The weave fineness of the airbag fabric refers to the weave fineness of the woven fabric constituting the fabric. The ratio of the warp and weft weave densities of the airbag fabric of this embodiment is preferably 0.8 to 1.2, more preferably 0.9 to 1.1, and even more preferably 0.95 to 1.05. By aligning the weave densities of the warp and weft, a woven fabric with good warp and weft balance can be obtained, and physical properties such as tensile strength, tear strength, and bias tensile strength can be prevented from decreasing drastically.

[0038] In order to improve the flatness of the woven fabric surface, it is important to reduce the meandering of the yarns in the thickness direction of the woven fabric on the side that is adhered to the film, in other words, to maintain high linearity of the fibers that make up the woven fabric. The degree of meandering of the yarns in the thickness direction of the woven fabric is expressed as the cut surface fiber meandering rate of the airbag base fabric.

[0039] The cut surface fiber meandering rate (%) at the film adhesive surface of the airbag fabric of this embodiment can be 2.0% to 7.0% in both the warp and weft directions, preferably 2.5% to 6.0%, and more preferably 3.0% to 5.0%. When the cut surface fiber meandering rate of the fabric is 7.0% or less, the bending of the fibers constituting the woven fabric becomes gentler, the flatness of the woven fabric surface is improved, and the adhesion between the film and the woven fabric can be improved. Furthermore, if the cut surface fiber meandering rate of the fabric is 2.0% or more, the warp and weft base fabric structure can be maintained even if a load is applied to the base fabric when the airbag is inflated, and the tensile strength and sewing strength of the base fabric can be prevented from being drastically reduced due to local changes in the weave density.

[0040] Furthermore, the sum of the cut surface fiber meandering ratios at the film adhesive surface in the warp and weft directions of the base fabric can be 5.0% or more and 12.0% or less, preferably 6.0% to 11.0%, and more preferably 7.0% to 10.0%. By setting the sum of the cut surface fiber meandering ratios in the warp and weft directions of the base fabric within the above range, it is possible to achieve both the tensile strength and slippage resistance of the base fabric and the adhesion between the film and the woven fabric. To improve the flatness of the base fabric, the cut surface fiber meandering ratio of the base fabric can be reduced by adjusting the weaving tension during woven fabric production, the calendaring of the base fabric surface, the film lamination process, and the warp and weft tension during the post-processing (heat setting) process. In woven fabrics with a cover factor of 2000 or less, there are many voids between the fibers constituting the woven fabric, and the degree of freedom of the yarn is high, so the fibers are prone to meandering in the thickness direction of the woven fabric due to the heat during the lamination process and the post-processing (heat setting) process. By maintaining a constant tension in this process, structural changes due to thermal shrinkage of the woven fabric can be suppressed, and the fiber meandering rate at the cut surface can be reduced. In order to effectively reduce the fiber meandering rate at the cut surface, it is preferable to use a processing method that includes both a process of flattening the entire structure of the base fabric, such as by applying processing tension during woven fabric production, and a process of flattening the surface of the base fabric, such as by calendering the surface of the base fabric.

[0041] The crimp rate (%) of the airbag fabric of this embodiment is preferably 2.0% to 7.0% in both the warp and weft directions, more preferably 2.5% to 6.5%, and even more preferably 3.0% to 5.0%. By adjusting the processing tension or the like to ensure that the crimp rate of the fabric falls within this range, it becomes easier to keep the cut surface fiber meandering rate at the film adhesive surface of the fabric within a preferred range.

[0042] The sum of the crimp rates in the warp and weft directions of the base fabric is preferably 5.0% or more and 12.0% or less, more preferably 6.0% to 10.0%, and even more preferably 7.0% to 9.0%. By setting the sum of the crimp rates in the warp and weft directions of the base fabric within the above range, it becomes easier to keep the sum of the cut surface fiber meandering rates at the film bonding surface in the warp and weft directions of the base fabric within a preferred range. The crimp rate can be reduced by adjusting the weaving tension during fabric production, the warp and weft tension during the film lamination process, and the post-processing (heat setting) process.

[0043] The degree of penetration of the resin component of the film into the woven fabric of the airbag fabric of this embodiment can be expressed as the coating-single yarn contact rate (%). The coating-single yarn contact rate can be calculated using the following formula: (Coating-single yarn contact rate (%)) = (Number of single yarns in contact with the coating) / (Number of single yarns of the fiber constituting the woven fabric). Here, the number of single yarns in contact with the coating refers to the number of single yarns that are in contact with the resin component of the film among the single yarns of the fiber constituting the woven fabric in the cross-sectional structure of the woven fabric, and refers to, for example, the number of black single yarns in FIG. 4. The coating-single yarn contact rate (%) of the airbag fabric of this embodiment can be 20% or more and 40% or less. A coating-single yarn contact rate of 20% or more can improve the adhesion between the film and the woven fabric, increase the tear strength of the fabric, and improve the scrubbing properties of the fabric. Even when a rubbing force is applied to the base fabric, minute peeling does not occur between the film and the woven fabric, and the film in areas with insufficient adhesion does not break due to being unable to withstand the rubbing force, thereby reducing the deterioration of breathability after rubbing. This prevents the film from peeling or being perforated when the airbag base fabric of this embodiment is sewn to a bag body or when inverted and stored after sewing. On the other hand, by setting the coating-single yarn contact rate to 40% or less, the resin component of the film does not penetrate too much into the woven fabric, allowing the fiber threads constituting the base fabric to have freedom to move slightly, resulting in high tear strength. In addition, the flexibility of the base fabric can be increased. Furthermore, even when a rubbing force is applied to the base fabric, localized force is unlikely to be applied to the resin component of the film, preventing damage to the film and reducing the deterioration of breathability after rubbing. The coating-single yarn contact rate of the base fabric is preferably 22% to 38%, more preferably 24% to 36%, even more preferably 25% to 35%, and particularly preferably 26% to 34%. The coating-single yarn contact rate of the airbag base fabric can be adjusted not only by the basis weight of the covering material (film), but also by changing the degree of penetration of the resin component of the film into the fabric, for example, by changing the flatness of the fabric, the single yarn diameter of the raw yarn constituting the fabric, and the processing method of the base fabric.

[0044] The basis weight of the airbag fabric of this embodiment is 100 g / m ２ More than 300g / m ２Preferably, 120 g / m or less ２ ~220g / m ２ More preferably, 140 g / m ２ ~210g / m ２ More preferably, 150 g / m ２ ~190g / m ２ It is more preferable that the weight of the base fabric is 100 g / m ２ If the thickness is more than 300 g / m, the mechanical strength and heat resistance of the base fabric are unlikely to be insufficient. ２ If it is below this value, the weight of the airbag will not be too heavy.

[0045] The thickness of the airbag fabric of this embodiment is preferably 0.20 mm or more and 0.30 mm or less, more preferably 0.20 mm to 0.28 mm, and even more preferably 0.20 to 0.25 mm. By setting the thickness of the fabric within the above range, it is possible to achieve both the mechanical strength and heat resistance of the fabric and the storage ability of the airbag.

[0046] The tensile strength (3 cm) of the airbag fabric of this embodiment is preferably 1000 N or more in both the warp and weft directions, more preferably 1500 N or more, and even more preferably 2000 N or more. If the tensile strength of the fabric is 1000 N or more, it can withstand the load during instantaneous inflation of the airbag. The upper limit of the tensile strength is not particularly limited, and may be, for example, 3000 N or less.

[0047] In addition, the tensile strength characteristic value F (N / (g / m ２ )) values ​​are 8.0 N / (g / m ２ ) or more, and 8.5 N / (g / m ２ ) or more, and 8.7 N / (g / m ２ ) or more, and more preferably 9.0 N / (g / m ２ Generally, there is a trade-off between increasing the tensile strength of a base fabric and decreasing the basis weight. ２) or more, it is possible to achieve both resistance to the load at the time of instantaneous inflation of the airbag and weight reduction of the base fabric. In order to increase the tensile strength characteristic value F, it is important to use a film with a small basis weight and to ensure that the warp and weft yarns constituting the base fabric are uniformly aligned without meandering or oblique. The upper limit of the tensile strength characteristic value F is not particularly limited, and is, for example, 20 N / (g / m ２ ) or less is sufficient.

[0048] The tear strength of the airbag fabric of this embodiment is preferably 250 N or more in both the warp and weft directions, more preferably 300 N or more, even more preferably 350 N or more, and even more preferably 400 N. When the tear strength of the fabric is 250 N or more, even if a local stress concentration occurs inside the cushion due to the complex cushion shape or sewing shape when the inside of the cushion is inflated, the fiber threads constituting the fabric can move slightly (yarn shift). This allows the stress to be effectively dispersed and the inflated state to be maintained without breakage. Therefore, more energy can be absorbed during a vehicle collision. That is, energy efficiency can be improved. In addition, even if the cushion is damaged by abrasion damage caused by the airbag device cover or vehicle interior parts, scratches are made in the cushion due to cuts caused by glass fragments, or pinholes are formed in the airbag base fabric due to inflator residue, etc., tears originating from these points are less likely to spread, and an extreme drop in the pressure inside the cushion can be prevented. There is no particular upper limit to the tear strength, and it may be, for example, 800 N or less.

[0049] The energy efficiency of an airbag during deployment can be evaluated by the base fabric's ability to maintain an internal pressure of 100 kPa and the burst absorption momentum. Here, the burst absorption momentum is the integral value (meaning the area of ​​the shaded area in Figure 8(A)) from the rise of the pressure curve to the point of bursting when gas is instantaneously released into the airbag connected to a burst test device such as that shown in Figure 7. ２The high internal pressure retention of the base fabric under 100 kPa means that there is very little gas leakage from the surface of the base fabric. In addition, a high burst absorption momentum indicates the potential to absorb the impulse during an actual occupant collision. When the pressure inside the airbag increases, the higher the tear strength of the base fabric, the easier it is to disperse stress against localized stress concentrations, making it less likely that stress concentrations that lead to bursting will occur, thereby increasing the burst absorption momentum. Note that Figure 8(B) shows the case where there is a rise point at the point where the pressure changes from negative to positive.

[0050] The tear strength characteristic value (T value) of the airbag fabric of this embodiment, which is the value obtained by dividing the tear strength by the basis weight of the fabric, is 1.6 N / (g / m ２ ) or more 5.0N / (g / m ２ ) or less. The lower limit of the tear strength characteristic value T is preferably 1.7 or more for both the warp and weft directions, more preferably 1.8 or more, even more preferably 1.9 or more, and particularly preferably 2.0 or more. The upper limit of the tear strength characteristic value T may be 5.0 or less for both the warp and weft directions. Generally, there is a trade-off between increasing the tear strength of a base fabric and reducing the basis weight. However, by setting the tear strength characteristic value T to 1.6 or more, it is possible to achieve both resistance to local stress concentration inside the cushion during instantaneous inflation of the airbag and weight reduction of the base fabric. In order to increase the tear strength characteristic value T, it is extremely important to adjust the degree to which the fibers constituting the base fabric restrict each other's movement while ensuring that the warp and weft yarns constituting the base fabric are uniformly aligned without meandering or oblique in the warp and weft directions. In other words, it is necessary to provide a restraining force sufficient to maintain the warp and weft base fabric structure itself without collapsing, while allowing the fiber threads that make up the base fabric to move slightly, and to efficiently disperse (propagate) stress when local stress is applied to the threads.

[0051] It is generally known that woven fabrics with a low cover factor (CF) have a tendency for the warp and weft fibers constituting the fabric to be separated (the yarns are coarse), and therefore exhibit high tear strength. However, the airbag fabric of this embodiment has a cover factor reduced to a level that makes it difficult to use with conventional silicone-coated fabrics. In an uncoated or silicone-coated fabric, the fibers constituting the fabric have a low mutual restraint force, so that even when a load is applied to the fabric during airbag inflation, the warp and weft fabric structure cannot be maintained, resulting in reduced tear strength. After extensive research and repeated experiments, the inventors of the present application unexpectedly discovered that even in woven fabrics with a cover factor of 2000 or less, by appropriately bonding the fabric and the film together without the warp and weft yarns constituting the fabric meandering or oblique in the warp and weft directions, the freedom of movement of the yarns can be reduced to a degree that allows the fibers constituting the fabric to maintain the warp and weft fabric structure, and when local stress is applied to the yarns, stress can be efficiently dispersed (propagated). The present invention was completed based on this unexpected discovery.

[0052] Furthermore, in conventional silicone-coated base fabrics, the higher the crimp rate of the woven fabric, the more slack (so-called "play") there is in the yarn length of the warp and weft fibers constituting the base fabric as they meander in the thickness direction of the fabric, making yarn shift more likely to occur and increasing the tear strength. However, for base fabrics obtained by bonding a film to a woven fabric with a cover factor of 2000 or less, rather than increasing the crimp rate of the woven fabric, the inventors of the present application unexpectedly discovered through extensive research and repeated experiments that by reducing the crimp rate of the woven fabric rather than increasing the crimp rate of the woven fabric, the bending of the fibers constituting the woven fabric becomes gentler, the flatness of the woven fabric surface is improved, and the adhesion between the film and the woven fabric is improved, thereby suppressing the freedom of movement of the yarns to an extent that the fibers constituting the base fabric can maintain the warp and weft fabric structure, efficiently propagating the local stress generated at the tear area to nearby yarns and increasing the tear strength of the base fabric. This has led to the completion of the present invention.

[0053] Furthermore, it has been found that the tear strength of the base fabric can be further increased by adjusting the thickness of the coating of the airbag fabric. As described above, the thickness of the coating of the airbag fabric of this embodiment can be 1 μm or more and 30 μm or less, preferably 2 to 20 μm, more preferably 3 to 17 μm, even more preferably 4 to 15 μm, and even more preferably 5 to 13 μm. In the airbag fabric of this embodiment, the tear strength can be increased by making the coating thickness 1 μm or more. Furthermore, by making the coating thickness 20 μm or less, when the film is coated on the woven fabric and bonded by lamination or the like, the resin component of the film does not penetrate too much into the woven fabric, allowing the fiber threads constituting the base fabric to move slightly, thereby improving the tear strength. Furthermore, if the coating thickness is 1 μm or more, it is possible to achieve a state in which the warp and weft base fabric structure itself is not destroyed. That is, the crimp rate of the woven fabric is reduced, and a film (coating material) of a predetermined basis weight and thickness is adhered to the woven fabric having a flat surface, and the resin component of the film does not penetrate too much into the woven fabric, but is adhered to the surface of the woven fabric to the extent that it does not destroy the base fabric structure itself (there is little resin derived from the film between the fibers constituting the woven fabric, but the interaction between the film and each single yarn is strong). By realizing this state, an airbag base fabric having excellent tear strength can be obtained. In addition, by using the manufacturing method of the airbag base fabric described later, it is possible to reduce the crimp rate and obtain a fabric with significantly higher flatness by using a fabric with a cover factor of 2000 or less, compared to a fabric with a cover factor of over 2000.

[0054] In the airbag fabric of this embodiment, the bias / parallel strength ratio can be 0.20 or more and 0.60 or less. The bias / parallel strength ratio can be calculated from the following formula: (Bias / parallel strength ratio) = {(bias direction tensile strength at 2 cm width) / 2} / (parallel direction tensile strength) Here, the bias direction tensile strength at 2 cm width is the strength when a fabric is cut to a size of 2 cm wide and 25 cm long, biased (45 °) relative to the warp and weft direction of the fabric, and the tensile strength is measured with a tensile tester, and the parallel direction tensile strength indicates the average tensile strength (N / cm) per 1 cm width in the warp and weft direction of the fabric. Increasing the bias direction tensile strength at 2 cm width improves the adhesion between the film and the fabric and makes it easier to propagate stress generated in the yarns constituting the fabric to nearby yarns. By setting the bias / parallel strength ratio to 0.20 or more, the tear strength of the fabric can be increased and the scrubability of the fabric can be improved. On the other hand, by setting the bias / parallel strength ratio to 0.60 or less, the resin component of the film does not penetrate too much into the woven fabric, allowing the fiber threads constituting the base fabric to have a degree of freedom for slight movement, resulting in high tear strength. Furthermore, the flexibility of the base fabric can be improved. That is, by setting the bias / parallel tensile strength ratio to 0.20 or more and 0.60 or less, the resin component of the film does not penetrate too much into the woven fabric, but is adhered to the surface of the woven fabric to a degree that does not destroy the base fabric structure itself (a state in which there is little resin derived from the film between the fibers constituting the woven fabric, but the interaction between the film and each single yarn is strong). The bias / parallel tensile strength ratio is preferably 0.22 or more and 0.55 or less, more preferably 0.25 or more and 0.50 or less, even more preferably 0.27 or more and 0.45 or less, and particularly preferably 0.30 or more and 0.40 or less. The bias direction tensile strength at a 2 cm width is preferably 200 N to 700 N, more preferably 250 N to 600 N, and even more preferably 300 N to 500 N. By setting the bias direction tensile strength at a 2 cm width within this range, it is possible to realize a degree of freedom in the yarns of the woven fabric in a state where the tear strength of the base fabric is high.

[0055] The slip resistance (N) of the airbag fabric of this embodiment is preferably 400N or more and 2000N or less in both the warp and weft directions, more preferably 500N or more and 1500N or less, even more preferably 600N or more and 1200N or less, and even more preferably 700N or more and 1000N or less. If the slip resistance of the base fabric is 400N or more, the fibers constituting the base fabric restrain each other's movement, and even if a load is applied to the base fabric when the airbag is inflated, the warp and weft base fabric structure can be maintained, and the tensile strength and sewing strength of the base fabric can be prevented from being drastically reduced due to local changes in the weave density. In addition, the opening of the base fabric when a load is applied to the sewing thread can be reduced, and gas leakage from the sewn parts under high pressure is suppressed, resulting in an airbag with good energy efficiency during airbag inflation. On the other hand, if the slip resistance of the base fabric is 2000 N or less, the fibers constituting the base fabric are not extremely constrained to each other, and can have the freedom to move while maintaining the warp and weft base fabric structure, so the base fabric becomes flexible and the storage capacity of the airbag is improved. The slip resistance of the airbag base fabric is measured using a 5 cm wide sample piece, but if the slip resistance value is too high to measure, the value measured using a 2.5 cm wide sample piece may be doubled to obtain the measured value of slip resistance.

[0056] The slip resistance (N) of the airbag fabric of this embodiment is divided by the basis weight of the fabric, which is the slip resistance characteristic value (E) (N / (g / m ２ The lower limit of the slippage resistance characteristic value (E) (N / (g / m ２The upper limit of the tear strength characteristic value T is preferably 20 or less, more preferably 6.0 or less, and even more preferably 5.0 or less for both the warp and weft directions. Generally, increasing the slippage resistance of a base fabric and reducing its basis weight are in a trade-off relationship. However, by setting the slippage resistance characteristic value E to 1.0 or more, it is possible to suppress the opening of seams (suppressing gas leakage) due to the local stress concentration inside the cushion during instantaneous inflation of the airbag, while also achieving a lightweight base fabric. In fabrics with extremely low cover factors (CF of 2000 or less), the warp and weft fibers constituting the fabric are spaced apart, allowing the threads to move freely within the fabric. This results in weak binding between the fibers, and the slippage resistance is significantly low when the fabric is uncoated or when it is coated with a silicone coating. However, by adhering the film to the base fabric in a state where the warp and weft yarns constituting the base fabric are uniformly aligned without meandering or tilting in the warp and weft directions and the flatness of the fabric surface is improved, the degree of freedom of movement of the fibers constituting the base fabric can be reduced, and the slippage resistance of the base fabric can be increased. This effect increases the stronger the adhesion between the film and the base fabric and the more the resin component of the film penetrates into the fabric.

[0057] The bending resistance (N) of the airbag fabric of this embodiment is preferably 15N or less in both the warp and weft directions, more preferably 12N or less, even more preferably 10N or less, and even more preferably 9N or less. When the bending resistance of the fabric is 15N or less, the thickness and bending rigidity when folding the airbag cushion are reduced, improving the storability of the airbag. The storability of the airbag can be evaluated by the ratio of the thickness of the two layers of the airbag fabric to the thickness of the bent portion. The lower limit of the bending resistance is not particularly limited, but may be 3N or more when manufacturing from a material having strength suitable for an airbag.

[0058] In addition, the bending resistance characteristic value S, defined as the bending resistance of the airbag fabric of this embodiment divided by the tensile strength of the fabric multiplied by 1000, is preferably 9.0 or less in both the warp and weft directions, more preferably 6.0 or less, and even more preferably 5.0 or less. The lower limit of the bending resistance characteristic value S is not particularly limited, and may be, for example, 2.0 or more. Generally, there is a trade-off between reducing the bending resistance of the fabric and increasing the tensile strength. However, by setting the bending resistance characteristic value S to 9.0 or less, it is possible to achieve both resistance to the load at the time of instantaneous inflation of the airbag and the storability of the airbag. In order to increase the value of the bending resistance characteristic value S, it is preferable to use a film with a small basis weight. Furthermore, by making the warp and weft yarns constituting the fabric uniformly aligned without meandering or oblique orientation, it is important to bring the tensile strength of the fabric closer to the value obtained by multiplying the tensile strength of the raw yarns of the constituent fibers by the number of fibers contained in the fabric (increasing the strength utilization rate).

[0059] The high-pressure air permeability (differential pressure 100 kPa) of the airbag fabric of this embodiment is 0.10 L / cm ２ / sec or less is preferable, and 0.03 L / cm ２ / sec or less is more preferable, and 0.01 L / cm ２ / sec or less is more preferable, and 0.001 L / cm ２ / sec or less is even more preferable. The high-pressure air permeability value of the base fabric is 0.10 L / cm ２ By keeping the airbag inflation time to 1 / sec or less, gas leakage during inflation and deployment of the airbag can be suppressed, and the energy efficiency during inflation of the airbag can be improved.

[0060] The sewing strength (N) of the airbag base fabric of this embodiment is preferably 600N to 2000N in both the warp and weft directions, more preferably 800N to 1500N, and even more preferably 1000N to 1200N. If the sewing strength of the base fabric is 600N or more, it can withstand the stress applied to the sewn portion during the instantaneous inflation of the airbag. There is no particular upper limit to the sewing strength, and it may be, for example, 3000N or less. In order to increase the sewing strength, it is important that the warp and weft yarns constituting the base fabric are uniformly aligned without meandering or oblique orientation, and that the film is uniformly bonded.

[0061] The scrub resistance (crunch resistance) of the airbag fabric of this embodiment is expressed in terms of the number of scrubs it can withstand. The scrub resistance of the airbag fabric of this embodiment is preferably 600 strokes (times) or more, more preferably 1000 strokes or more, even more preferably 1500 strokes or more, and even more preferably 2000 strokes or more. By making the scrub resistance 600 strokes or more, friction between the fabrics when the folded airbag is inflated and deployed, or contact with the airbag cover or vehicle interior material, etc., can occur, preventing a peeling phenomenon in which the film peels off and the internal pressure of the airbag from decreasing. In order to improve scrub resistance, not only is the adhesion between the film and the woven fabric good, but the flexibility of the film itself and the film thickness are uniform and not partially thinned due to local penetration of the film into the woven fabric. It is important that the stress of the rubbing does not concentrate at the interface between the film and the woven fabric.

[0062] (Method for manufacturing airbag fabric) The method for manufacturing the airbag fabric of this embodiment is not particularly limited, but the properties of the airbag fabric can be improved as follows. Another embodiment of the present invention can be a method for manufacturing the airbag fabric, comprising the following steps: a laminating step of adhering a film to at least one side of a woven fabric while applying tension in the warp and / or weft directions of the woven fabric; and a heat treatment step of heating the woven fabric laminated with the obtained film at a temperature of 150 ° C. or higher while applying tension in the warp and / or weft directions of the woven fabric. In such a manufacturing method, it is preferable that the ratio of the tear strength of the woven fabric laminated with the film after the heat treatment process to the tear strength of the woven fabric subjected to the laminating process is 100% or more and 500% or less in both warp and weft directions of the woven fabric, and it is also preferable that the ratio of the slippage resistance of the woven fabric laminated with the film after the heat treatment process to the slippage resistance of the woven fabric subjected to the laminating process is 200% or more and 2000% or less in both warp and weft directions of the woven fabric.

[0063] The hot water dimensional change rate of the raw yarn used in the airbag fabric of this embodiment is preferably 5% or more and 10% or less. By setting the hot water dimensional change rate of the raw yarn to 5% or more, the crimp rate can be reduced by heating while applying tension in the post-processing process. On the other hand, by setting the hot water dimensional change rate of the raw yarn to 10% or less, the dimensional stability of the woven fabric after processing can be improved. The hot water dimensional change rate of the raw yarn is more preferably 6% or more, and even more preferably 7% or more.

[0064] The raw yarns used in the airbag fabric of this embodiment are preferably entangled by interlacing in a range of 5 to 50 yarns / m. By setting the entanglement to 5 yarns / m or more, the generation of fuzz during weaving can be suppressed. Furthermore, by setting the entanglement to 50 yarns / m or less, in a woven fabric with a small cover factor, the single yarns are separated on the surface of the woven fabric, improving the flatness of the woven fabric and improving the adhesion of the film. The entanglement is more preferably 40 yarns / m or less, even more preferably 30 yarns / m or less, and even more preferably 20 yarns / m or less. Furthermore, it is preferable that there are more areas where some single yarns are entangled but the remaining single yarns are not entangled (weak entanglement) than areas where all single yarns are entangled (strong entanglement). By doing so, the generation of fuzz during weaving can be suppressed while improving the flatness of the woven fabric.

[0065] For the production of the airbag fabric of this embodiment, for example, a loom such as a water jet loom, an air jet loom, a rapier loom, a projectile loom, or a multi-phase loom can be used, but is not limited to these. Using a water jet loom is preferable because it can remove oil adhering to the raw yarn and improve adhesion to the film. When weaving, it is preferable to use a full-face temple or a ring temple. In addition, extra yarns may be used at both ends of the fabric to correct slack in the fabric.

[0066] The warp tension when weaving the airbag fabric of this embodiment is preferably 0.25 cN / dtex or more and 0.50 cN / dtex or less, more preferably 0.25 cN / dtex to 0.40 cN / dtex, and even more preferably 0.25 cN / dtex to 0.35 cN / dtex. In the gray machine after weaving, the crimp rate in the warp direction is usually high. By setting the warp tension to 0.25 cN / dtex or more, the crimp rate in the vertical direction can be reduced, improving the flatness of the airbag fabric. Furthermore, by setting the warp tension to 0.50 cN / dtex or less, the generation of warp fuzz due to friction with the reed and heald (harness) can be suppressed.

[0067] The winding tension when weaving the airbag fabric of this embodiment is preferably 0.4 to 2.0 times the warp tension, more preferably 0.6 to 1.8 times, even more preferably 0.8 to 1.6 times, and even more preferably 1.0 to 1.6 times. In a woven structure with a cover factor of 2000 or less, the degree of freedom of the fibers constituting the woven fabric is high, so by setting the winding tension during weaving to 0.4 times or more the warp tension, the woven structure can be prevented from loosening after weaving and the crimp rate in the warp and weft directions can be prevented from changing. On the other hand, by setting the winding tension during weaving to 2.0 times or less the warp tension, the woven structure can be stabilized.

[0068] In the airbag fabric of this embodiment, the oil agent and the like attached to the woven fabric in the scouring process after weaving can be refined using a scouring agent to improve adhesion to the film. In the scouring process, it is preferable to perform scouring while applying tension in the warp direction to prevent the woven structure from loosening and the crimp rate from increasing in the warp and weft directions.

[0069] In the airbag fabric of this embodiment, the woven fabric can be covered with a film by laminating it. However, before covering the woven fabric with the film, the woven fabric surface can be flattened to reduce the cross-sectional fiber meandering rate at the film adhesion surface. By adhering a film to a woven fabric with a flat surface, the contact area between the film and the woven fabric increases, thereby achieving sufficient adhesion without applying excessive heat or pressure during thermal lamination and suppressing the occurrence of pinholes. Since the occurrence of pinholes can be suppressed, thin films can be easily applied, and an airbag fabric with excellent flexibility can be obtained. Furthermore, since the woven fabric is flat, heat and pressure can be applied uniformly to the film during thermal lamination, so the resin component of the film does not penetrate deep into the woven fabric, such as between the woven yarns, and fill therein, resulting in a flexible airbag fabric with good scrub resistance. Furthermore, since the contact area between the fibers constituting the fabric and the film is likely to increase, adhesion to the woven fabric is improved even with a thin film, and the freedom of movement of the fiber threads constituting the fabric can be reduced. The method of flattening the woven fabric before covering with a laminate is not limited, but calendering is preferred for its simplicity. The calendering temperature is preferably 100°C or higher and 220°C or lower. If the temperature is 100°C or higher, the woven fabric structure after calendering can be maintained, and if the temperature is 220°C or lower, the woven fabric will not undergo thermal degradation. The calendering line pressure is preferably 0.5 kN / cm or higher and 15 kN / cm or lower. If the pressure is 0.5 kN / cm or higher, the woven fabric structure after calendering can be flattened, improving adhesion to the film. On the other hand, if the calendering pressure is 15 kN / cm or lower, the woven fabric will become paper-like and will not become hard. Calendering is preferably performed on one side of the woven fabric, i.e., the side to be laminated. By calendering one side of the woven fabric, the flatness required for adhesion to the film can be maintained, while the woven fabric will not become paper-like and hard.

[0070] When covering the airbag fabric of this embodiment with a film by lamination, it is important to apply tension to the woven fabric. In a woven fabric structure with a small cover factor, the fibers constituting the woven fabric have a high degree of freedom, so by applying tension to the woven fabric while performing thermocompression bonding, the warp and weft yarns constituting the base fabric can be prevented from moving and meandering or obliquely due to the heat and pressure of the lamination process. In addition, by applying tension to the woven fabric, the low crimp rate of the woven fabric can be maintained or further reduced even if thermal shrinkage of the fibers occurs. Examples of lamination methods include a roll-type thermal lamination method in which a film and a woven fabric are superimposed and continuously laminated in a roll-to-roll manner using a heated roll, a belt-type thermal lamination method in which a film and a woven fabric are superimposed and then fed between a pair of heated belts and heat-laminated while being pressurized, a vacuum lamination method in which lamination is performed under reduced pressure, and a lamination method using a heat press. However, the roll-type thermal lamination method is preferred, as it is easy to apply tension in the warp direction of the woven fabric. The rolls may be a pair, or multiple rolls may be passed continuously. The tension in the warp direction when laminating the airbag base fabric of this embodiment is preferably 0.05 cN / dtex or more and 0.20 cN / dtex or less, more preferably 0.06 cN / dtex to 0.18 cN / dtex, and even more preferably 0.07 cN / dtex to 0.15 cN / dtex. Heating conditions during thermal lamination are preferably within a temperature range of from the melting point of the resin contained in the adhesive layer (preferably the resin contained in the adhesive layer in the largest amount) to the melting point + 40°C, and are preferably within a temperature range of from the melting point - 40°C to the melting point of the resin contained in the outer layer (preferably the resin contained in the outer layer in the largest amount). By doing so, a portion of the film is adhered to the fabric in a solid state, so that, compared to coating in a liquid state, deterioration in breathability under high pressure due to unevenness in the thickness of the coating or deterioration in breathability after crumpling are less likely to occur. Furthermore, pressure conditions during thermal lamination include roll type: 1 to 30 N / cm, belt type, and heat press type: 1 to 20 N / cm. ２ More preferably, the roll type is 10 to 20 N / cm, and the belt type and heat press type are 5 to 20 N / cm. ２When the heating conditions and pressure conditions are within the above ranges, the adhesive strength between the film and the base fabric is exhibited, and the occurrence of pinholes in the film during lamination can be suppressed.

[0071] The airbag fabric of this embodiment can be subjected to a heat setting process (post-heat treatment) after covering the woven fabric with a film. In this process, the applied thermal energy allows the resin component of the film to penetrate between the fibers of the woven fabric, thereby increasing the adhesion between the base fabric and the film. Examples of post-heat treatment methods include a method in which the base fabric is continuously brought into contact with a heated roll, and a method in which the base fabric is continuously heat-treated without contact using hot air or an infrared heater. In the post-heat treatment, it is preferable to heat the base fabric while fixing or applying tension in the warp and / or weft directions. For example, the base fabric can be fixed using a pin tenter or continuously heat-treated while applying tension to the base fabric. By applying fixation or tension in the warp and weft directions, the flatness of the base fabric can be further improved, and the warp and weft yarns constituting the base fabric can be uniformly aligned without meandering or oblique orientation. Furthermore, when the fabric structure changes due to fiber shrinkage caused by thermal energy, the resin component of the film can be prevented from penetrating between the fibers of the fabric more than necessary, which would cause the base fabric to become hard or the tear strength to decrease, which is preferable.

[0072] The warp tension applied to the base fabric during the heat treatment step is preferably 0.05 cN / dtex to 0.30 cN / dtex, more preferably 0.08 cN / dtex to 0.25 cN / dtex, and even more preferably 0.10 cN / dtex to 0.20 cN / dtex. By applying a warp tension of 0.05 cN / dtex or more during the heat treatment step, the crimp rate in the warp direction can be reduced. On the other hand, by setting the tension to 0.30 cN / dtex or less, dimensional change after processing can be reduced. Furthermore, during pinning, the crimp rate in the weft direction can be reduced by not performing width setting or by performing width setting. The width setting rate is preferably 0% to 5%, and more preferably 0.1% to 3%. The heating conditions during the heat treatment step are preferably 150° C. or higher, or within a temperature range from the melting point of the resin contained in the adhesive layer (preferably the resin contained in the adhesive layer in the largest amount) to the melting point + 40° C. After the heat treatment step, it is preferable not to reduce the tension of the base fabric until the temperature of the base fabric drops to or below the glass transition temperature of the fibers constituting the woven fabric.

[0073] By performing the above-mentioned surface flattening treatment and base fabric tension control, etc., it is possible to reduce the crimp rate and obtain a fabric with significantly higher flatness when using a fabric with a cover factor of 2000 or less, compared to a fabric with a cover factor of over 2000. In a fabric with an extremely low cover factor (a cover factor of 2000 or less), the weft and warp fibers constituting the fabric are spaced apart, allowing for a high degree of freedom of movement of the yarns within the fabric, making it easy to reduce the crimp rate. However, if the tension during processing is relaxed, the weft and warp crimp rate is likely to change. By maintaining a certain level of tension or higher in each process from the weaving process to the heat treatment process, it is possible to prevent the weft and warp crimp rate from increasing.

[0074] In the airbag fabric of this embodiment, the tear strength of the fabric can be 100% or more and 500% or less in the warp and weft directions of the fabric relative to the tear strength of the fabric (base fabric) before it is coated with the covering material. By lowering the tear strength of the base fabric and increasing the tear strength by coating with the covering material, it is possible to achieve both slip resistance and scrub resistance of the base fabric while maintaining a base fabric that is easy to transmit stress. A more preferable range of the ratio of the tear strength of the fabric (base fabric) before it is coated with the covering material to the tear strength of the airbag fabric after it is coated with the covering material is 120% or more and 500% or less, and an even more preferable range is 140% or more and 500% or less.

[0075] In the airbag fabric of this embodiment, the slip resistance of the base fabric can be 200% or more and 2000% or less in both warp and weft directions relative to the slip resistance of the woven fabric (base fabric) before it is coated with the covering material. By reducing the slip resistance before coating with the covering material, tension is applied to the base fabric in the base fabric processing process, making it easier to uniformize the woven structure and flatten the woven surface. Furthermore, by increasing the slip resistance by coating with the covering material, it is possible to achieve both slip resistance and the tear strength and scrub resistance of the base fabric. A more preferred range of the ratio of the slip resistance of the woven fabric (base fabric) before it is coated with the covering material to the slip resistance of the airbag fabric after it is coated with the covering material is 300% or more and 2000% or less, and an even more preferred range is 400% or more and 2000% or less. The slip resistance of the woven fabric (base fabric) before being coated with the covering material is preferably 500 N or less, more preferably 200 N or less, and even more preferably 100 N or less. From the viewpoint of handling during processing, the slip resistance of the woven fabric (base fabric) before being coated with the covering material is preferably 20 N or more.

[0076] (Airbag) The airbag fabric of this embodiment can be used as an airbag. By using the airbag fabric in the inflation portion (chamber) of the airbag, it is possible to create an airbag cushion that is flexible, lightweight, and easy to store, has good energy efficiency in airbag inflation, and is less likely to tear at the seams even under high pressure. When the airbag fabric is used in the inflation portion of the airbag, a covering material may be disposed inside the bag body of the airbag (the side filled with gas), or a covering material can be disposed on the outside of the bag body. By disposing a covering material inside the bag body of the airbag, the woven fabric can be protected from high-temperature gas generated from the inflator. By disposing a covering material on the outside of the bag body of the airbag, the base fabric can be protected from abrasion when it comes into contact with vehicle interior materials, etc. when the airbag is deployed. Furthermore, the base fabric constituting the airbag preferably has a mass ratio of a base fabric using a film as a covering material to a base fabric using a silicone coating of 7:3 or more, more preferably 8:2 or more, and it is particularly preferable that no silicone-coated base fabric is used. By reducing the proportion of silicone-coated base fabric, it is possible to improve recyclability and create an airbag cushion with less environmental impact.

[0077] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0078] (1) Constituent Yarn Fineness The apparent fineness of 50 yarns taken out of each warp and weft direction from the airbag fabric was measured according to Appendix H of JIS L 1096:2020. This was done five times, and the average value was taken as the fineness (dtex) of the constituent yarn. When it is difficult to take out all the filaments contained in one yarn (multifilament) from the airbag fabric, the fineness of the constituent yarn can also be determined by the following method. The cross section of the airbag fabric was observed with a scanning electron microscope (VE-9800 manufactured by KEYENCE), the total cross-sectional area of ​​all filaments contained in one yarn (multifilament) was calculated, and the average value of 10 measurements was taken as A (cm ２ Next, the density D (g / cm 3 ) of the yarn taken out from the airbag fabric is３ ) was measured, and (fineness) = D × A × 10 ７ was requested as follows.

[0079] (2) Density The density of the yarn taken out from the airbag fabric was determined by the density measurement method (density gradient tube method) according to JIS L 1093.

[0080] (3) Number of Single Yarns The cross section of the airbag fabric was observed with a scanning electron microscope (VE-9800 manufactured by KEYENCE), the number of filaments in 10 warp and weft weave yarns was counted, and the most frequent number of filaments among the 10 was taken as the number of single yarns.

[0081] (4) Single Yarn Fineness The single yarn fineness (dtex) was calculated by dividing the constituent yarn fineness by the number of filaments.

[0082] (5) Weave density (threads / inch (2.54 cm)) Measured according to JIS L1096:2020 8.6.1b) B method in accordance with Appendix FA.

[0083] (6) Weave Fineness (WF) The weave fineness (WF) of the airbag fabric is calculated by the following formula: WF = {(d) × (1.14 / D)} × (2 × W) (where d is the warp and weft average total fineness (dtex) of the constituent yarns, and D is the density of the constituent yarns (g / cm ３ ) and W is the warp and weft average weave density (counts / inch (2.54 cm)).

[0084] (7) Cover Factor (CF) The cover factor (CF) of an airbag fabric is calculated by the following formula: CF = √{(d) × (1.14 / D)} × (2 × W) (where d is the warp and weft average total fineness (dtex) of the constituent yarns, and D is the density (g / cm ３ ) and W is the warp and weft average weave density (counts / inch (2.54 cm)).

[0085] (8) Crimp rate (%) and sum of warp and weft crimp rates were measured in accordance with the method for measuring the weave shrinkage rate of yarn taken out of fabric (Method B) described in JIS L 1096:2020. However, the load when measuring the length of a straight stretched yarn was 9.3 mN / tex. The warp and weft crimp rates were added together to determine the sum of the crimp rates (%).

[0086] (9) Cut Surface Fiber Serpentine Ratio (%) and Sum of Weft and Warp The A-A' cross section of the airbag fabric shown in FIG. 7 was observed using a scanning electron microscope (VE-9800 manufactured by KEYENCE), and a cross-sectional image such as that shown in FIG. 8 was obtained with the film adhesive surface facing up. An arc passing through three points, the left end (a), the bottom end (b), and the right end (a'), of the cross section of one yarn (aggregate of multifilaments) on the film adhesive surface side, was drawn, and the length of the arc was P and the length of the straight line segment a-a' was Q. The value of P / Q was recorded, and the average value of the P / Q values ​​at 20 different locations was used as the cut surface fiber serpentine ratio for each warp and weft. Note that the cut surface fiber serpentine ratio (%) = {(P / Q) - 1} × 100. The sum (%) of the cut surface fiber serpentine ratios (%) was calculated by adding the warp and weft cut surface fiber serpentine ratios (%).

[0087] (10) Coating Thickness (μm) A 1 cm x 1 cm sample was taken from the airbag base fabric. For example, two 1 mm thick polypropylene sheets (size: 5 mm x 10 mm) coated with EVA adhesive were prepared. The sample was sandwiched between the two polypropylene sheets with the EVA adhesive side facing inward to form a single integrated unit. A 5 μm to 10 μm thick A-A' cross section (section) was taken using a microtome, and an enlarged image was taken using a scanning electron microscope (SEM) so that the fiber bundle could fit in a single image. Next, the horizontal distance between both ends of the fiber bundle in the enlarged image was measured, the midpoint of the fiber bundle was determined, and a vertical line was drawn at the midpoint. Regarding the coating thickness of the film, when the vertical line intersected with the uppermost single yarn (see Figure 6(A)), the thickness of the film was measured based on the top end of the single yarn, and this was used as the coating thickness. Furthermore, when a vertical line passes between two single yarns (see FIG. 6B), the coating thickness (t1 and t2) was measured from the upper ends of the left and right single yarns, and the average value was used as the coating thickness. That is, the coating thickness was calculated as (t) = (t1 + t2) / 2. The coating thickness was measured for 20 fiber bundles (10 locations on each of the warp and weft cross sections), and the average value was used as the coating thickness (μm) of the airbag base fabric.

[0088] (11) Coating-single yarn contact rate (%) The A-A' cross section of the airbag fabric shown in FIG. 9 was observed using a scanning electron microscope (VE-9800 manufactured by KEYENCE), and a cross-sectional image such as that shown in FIG. 10 was obtained with the film adhesive surface facing up. The number of single yarns in contact with the resin component of the film in a single yarn (multifilament aggregate) on the film adhesive surface side of the cross-sectional image was recorded. When the average value of the values ​​at 20 different locations (10 locations each in the warp and weft cross sections) was taken as the number of single yarns in contact with the coating, the coating-single yarn contact rate was calculated using the following formula: (Coating-single yarn contact rate (%)) = (Number of single yarns in contact with the coating) / (Number of single yarns of fibers constituting the woven fabric) × 100. Note that in FIGS. 10(A) and 10(B), the number of single yarns of the fibers constituting the woven fabric is shown as 30, but this is for illustrative purposes only. In Examples 1 to 10 described below, the number of single yarns was 105 to 144. In Figure 10(A), there are 15 single yarns in contact with the coating shown in black, so the coating-single yarn contact rate is 50%, while in Figure 10(B), there are 23 single yarns in contact with the coating, so the coating-single yarn contact rate is 23 / 30 x 100 = 77%.

[0089] (12) Weight (g / m ２ ) Basis weight (g / m2) of airbag fabric (including covering material) ２ ) was determined from the mass per unit area measured in accordance with 8.3.2 of JIS L 1096:2010. The basis weight of the base fabric was measured by taking a sample of the base fabric before covering with the covering material.

[0090] (13) Thickness (mm) Five 100 mm x 100 mm samples were taken, and the thickness (mm) of the airbag base fabric was measured according to the thickness B method described in JIS L 1096:2020. The applied pressure was 1 kPa, and a presser foot with a diameter of 10.5 mm was used. The thickness of each sample was measured, and the average value was calculated.

[0091] (14) Tensile strength (3 cm), bias tensile strength (2 cm), bias / parallel tensile strength ratio The tensile strength of the airbag base fabric was measured according to the method described in JIS L 1096:2020 (Method A (Labeled Strip Method)), and the tensile strength at a base fabric width of 3 cm was recorded as the tensile strength (3 cm). The tensile strength (N / cm) per 1 cm width is obtained by dividing the tensile strength (3 cm) value by 3. (Bias / parallel strength ratio) The fabric was cut with scissors to a size of 2 cm wide and 20 cm long so that it was bias (45 °) relative to the warp and weft direction of the fabric, and the tensile strength was measured with a tensile tester. The chuck distance was 10 cm and the tensile speed was 20 cm / min. Test conditions other than those described above were in accordance with the method described in JIS L 1096:2020 (Method A (Cut Strip Method)). The average of five measurements was taken as the bias direction tensile strength over a 2 cm width, and the bias / parallel strength ratio was calculated using the following formula: (Bias / parallel strength ratio) = {(bias direction tensile strength over a 2 cm width) / 2} / (parallel direction tensile strength) Here, the parallel direction tensile strength refers to the average value (N / cm) of the tensile strength per 1 cm width in the warp and weft directions of the fabric.

[0092] (15) Tear strength (N) The tear strength of the airbag base fabric was measured in accordance with the tear strength A-1 method (single tongue method) described in JIS L 1096:2020. In the obtained S-S curve, the average value of the first to third highest peak values ​​(TOP3 value) among all peak values ​​excluding the peak value with the shortest tensile distance was recorded as the tear strength of the airbag base fabric. The tear strength of the base fabric was measured by collecting the base fabric in a state before coating with the covering material.

[0093] (16) Slip resistance (N) According to ASTM D6479, measurements were made five times in each warp and weft direction, and the average of the ten measurements was taken as the slip resistance (N). The slip resistance of the airbag fabric is measured using a 5 cm wide sample piece. However, if the slip resistance value is too high to measure, the value measured using a 2.5 cm wide sample piece may be doubled to be used as the measured value of slip resistance. The slip resistance of the base fabric was measured by taking a sample of the base fabric before it was covered with the covering material.

[0094] (17) Bending Resistance The bending resistance (N) of the airbag base fabric was measured according to the method described in ASTM D6479.

[0095] (18) High-pressure air permeability (L / cm ２ The base fabric was held in a φ100 mm jig, pressure was applied to one side of the base fabric, and the differential pressure between the two sides of the base fabric was adjusted to 100 kPa, and the air flow rate passing through at that time was measured with a laminar flow tube type flowmeter. Measurements were taken at five random locations within the same sample and the average value was calculated.

[0096] (19) Sewing strength (N) The sewing strength of the airbag base fabric was measured according to the seam strength A-1 method (grab method / horizontal seam method) described in JIS L 1093: 2011. For the sewing thread, Gunze airbag sewing thread (total fineness 1400 dtex, nylon 66 multifilament fiber 700 dtex 2-ply twist) was used as the upper thread and lower thread, and sewn together with a lock stitch so that the number of stitches per 10 cm was 50.

[0097] (20) Scrub (number of times) Using a scrub tester (manufactured by Imoto Machinery Co., Ltd.), the test was performed five times in both the longitudinal and longitudinal directions at an initial load of 10 N in accordance with ISO 5981, and the average value was recorded as the number of scrubs (number of times). If the number of tests at which the laminate began to peel from the base fabric was less than 2000 times, the number was recorded, and if there was no peeling even after more than 2000 times, the number was recorded as 2000.

[0098] (21) Tensile strength characteristic value (F) (N / (g / m ２ The tensile strength (3 cm) of (14) above is divided by the basis weight of (12) above to obtain the tensile strength characteristic value (F) (N / (g / m ２ ))

[0099] (22) Tear strength characteristic value (T) (N / (g / m ２ The tear strength (15) above is divided by the basis weight (12) above to obtain the tear strength characteristic value (T) (N / (g / m ２ ))

[0100] (23) Slip resistance characteristic value (E) (N / (g / m ２ The value obtained by dividing the slippage resistance (N) in (16) above by the basis weight in (12) above is the slippage resistance characteristic value (E) (N / (g / m ２))

[0101] (24) Bending Resistance Characteristic Value (S) (-) The bending resistance in (17) above was divided by the tensile strength (3 cm) in (14) above and multiplied by 1000 to obtain the bending resistance characteristic value (S).

[0102] (25) Ratio of the thickness of two layers of airbag fabric to the thickness of the bent portion (bent portion thickness / two-layer thickness) The thickness (mm) of two layers of airbag fabric was measured according to JIS L1019 using a thickness meter (FFA-10 manufactured by Ozaki Seisakusho). Next, the airbag fabric was cut to a width of 5 cm and a length of 10 cm to create a sample piece. The sample piece was folded once in the lengthwise direction so that the film side or silicone side was on the inside, and the fold of the sample piece was sandwiched under a 3 cm x 6 cm metal plate. A weight was placed on the metal plate for 30 seconds so that the total weight together with the metal plate was 10 kg. Then, using the same thickness meter, the probe was set so that the bent portion was on the center line of the probe of the thickness meter as shown in FIG. 2, and the value after 1 minute had stabilised was measured. The value was calculated by dividing the thickness (mm) of the bent portion by the thickness (mm) of the two layers of fabric. This measurement was carried out five times in each of the warp and weft directions, and the average value was taken as the ratio of the thickness of the two layers of base fabric to the thickness of the bent portion.

[0103] (26) Internal pressure retention under 100 kPa (%) A sample (laminated base fabric) cut to a diameter of 135 mm was set in the upper opening of the airtightness measurement device shown in Figure 3, and the internal pressure retention rate was determined 10 seconds after air was supplied to an internal pressure of 100 kPa. A new sample was prepared for the measurement, and the measurement was repeated three times to determine the average value. The main specifications and measurement conditions of the airtightness measurement device were as follows: (Airtightness measurement device) Diameter of upper opening (a): Approximately 101 mm (the inner diameter of the O-ring was used as the opening) Surface area of ​​upper opening (b): 80 cm ２ ・Volume of pressure vessel (c): 881 cm ３ ・Volume of volume-adjusting aluminum round bar (d): 572 cm ３ Actual volume (cd): 309 cm ３(Control device) Flow meter: Flow Master DR-10 (manufactured by SB Environment Co., Ltd.) (Measurement conditions) Upper flange fixing bolt tightening torque: 5 N-m Air supply pressure: 0.5 MPa Air supply rate: 2 L / min Internal pressure measurement interval: 1 sec (Measurement sample) Size: diameter 130 mm Installation direction: set so that the coating material faces the outer surface of the pressure vessel

[0104] (27) Burst pressure (kPa), burst absorption momentum (N·sec / m ２ Two pieces of fabric cut into the shape shown in Figure 1 were stacked with the film or coated side facing inward, and the outer periphery was sewn with a single row lock stitch (50 stitches / 10 cm pitch) using sewing thread (Gunze nylon 66, 1400 dtex) with a 10 mm seam allowance. Using the same sewing conditions, a circular stitch with a diameter of 45 mm was sewn in the center to obtain an airbag for evaluation. The fabricated airbag for evaluation was connected to a burst test device as shown in Figure 7, and a pressure port (Kyowa Electronics) was attached to the airbag to measure the internal pressure. Nitrogen gas was charged into a tank (30.05 L capacity) in the device until it reached 1.0 MPa, and gas was instantly released into the airbag by opening the solenoid valve. A graph (Figure 5) of the internal pressure over time until the airbag burst was obtained. The maximum pressure shown on the graph was recorded as the pressure at the time of burst (burst pressure). The integral value from the rise of the pressure curve in the graph to the time of burst (meaning the area of ​​the shaded area in FIG. 5) is the burst absorption momentum (N·sec / m ２ ) was recorded. Here, if there is a portion where the pressure curve of the graph becomes negative pressure (see Figure 5 (B)), the point where the pressure changes from negative pressure to positive pressure was taken as the rising point. Of the tears (continuous ruptures on the surface of the base fabric) observed on the surface of the evaluation airbag after the burst test, the longest was recorded as the burst tear length. However, for each evaluation value, the average value of three tests was taken as the evaluation result.

[0105] (28) Rate of change in air permeability before and after rubbing Ten test pieces in accordance with ISO 5981 were prepared in both the warp and weft directions. Half of the test pieces were used to perform a test in accordance with ISO 5981 using a scrub tester (manufactured by Imoto Seisakusho) with an initial load of 1 kgf, and the samples were taken out when the number of tests reached 100. By the above operation, five samples after rubbing and five samples before rubbing that were not rubbing were obtained in both the warp and weft directions. Next, in accordance with JIS L1096 (2010). 8.26.1A Frazier type method, the air permeability (cc / cm) of the samples obtained by the above operation at a differential pressure of 125 Pa was measured using a Frazier type tester (FX-3300 LabAir IV). ２ / sec) was measured. The measurement range was 5 cm ２ The average values ​​of the results for the five samples after rubbing and before rubbing were taken as the air permeability after rubbing and before rubbing, respectively, and the rate of change in air permeability before and after rubbing was calculated for each process using the following formula: (rate of change in air permeability before and after rubbing) = (air permeability after rubbing) / (air permeability before rubbing).

[0106] (29) Melting Point (Tm) of Film Raw Material A sheet having a thickness of 150 μm was prepared using a press molding machine “P2-30T-400” manufactured by Toyo Seiki Seisakusho, Ltd., and the melting peak temperature obtained at a temperature increase rate of 10° C. / min using DSC was taken as the melting point (in accordance with JIS 7121).

[0107] (30) Glass Transition Temperature (Tg) of Film Raw Material A 0.9 mm thick sheet was produced using a press molding machine "P2-30T-400" manufactured by Toyo Seiki Seisakusho, and the loss tangent tanδ was measured using a dynamic viscoelasticity measuring device ("MCR301" manufactured by Anton Paar) in accordance with JIS 7244-2, and the peak temperature of the loss tangent tanδ was taken as the glass transition temperature. - Measurement mode: Torsion (Measurement attachment: SRF10) - Sample: Thickness = 0.9 mm, Width = 10 mm, Measurement span = 38 mm - Normal force: -0.3 N - Oscillation angle: 0.1% - Frequency: 1 Hz - Heating rate: 1.5°C / min

[0108] [Example 1] (Multilayer film) A three-kind, three-layer multilayer film having a layer structure (volume %) of "adhesive layer (20%) / / intermediate layer (60%) / / outer layer (20%)" was used. The adhesive layer was made of a polyamide 6 / 12 copolymer [trade name "Ube Nylon 7128B" (manufactured by Ube Industries, Ltd.), Tg = 47°C, Tm = 128°C], the intermediate layer was made of an acid-modified polyolefin composition [trade name "Admer NF587" (manufactured by Mitsui Chemicals, Ltd.), Tg = -24°C, Tm = 121°C], and the outer layer was made of a polyamide 6 / 66 copolymer [trade name "Ube Nylon 5033B" (manufactured by Ube Industries, Ltd.), Tg = 17°C, Tm = 197°C]. The film was extruded by inflation molding to a basis weight of 10 g / m. ２ A multilayer film of the above formula was obtained. (Fabric) A plain weave fabric was woven using a water jet loom using nylon 66 yarn with a fineness of 490 dtex and 136 single yarns, followed by scouring and drying. The warp tension during weaving was 0.3 cN / dtex. (Calendaring, Laminating) Using a heater roll and a resin roll, one side of the fabric was subjected to a flattening treatment by calendaring at a temperature of 135°C and a linear pressure of 2.0 kN / cm. Subsequently, the multilayer film was laminated on the flattened fabric side and bonded by lamination. The lamination conditions were as follows: Temperature: 160°C Roll speed: 15m / min Linear pressure: 0.5kN / cm Warp tension during lamination: 0.1cN / dtex (Post-heating) Subsequently, the obtained base fabric was subjected to a post-heating treatment at a temperature of 190°C for 3 minutes using a pin tenter. The tentering ratio when introduced into the pin tenter was 0%, and the warp tension was 0.15cN / dtex. The physical properties of the obtained airbag base fabric are shown in Table 1 below.

[0109] [Example 2] The coating material has a basis weight of 20 g / m ２ An airbag base fabric was produced in the same manner as in Example 1, except that the airbag base fabric was changed to the above. The physical properties of the obtained airbag base fabric are shown in Table 1 below.

[0110] [Example 3] An airbag base fabric was produced in the same manner as in Example 1, except that the constituent yarn fineness was 350 dtex, the single yarn fineness was 2.6 dtex, and the weave density was changed. The physical properties of the obtained airbag base fabric are shown in Table 1 below.

[0111] [Example 4] An airbag base fabric was produced in the same manner as in Example 1, except that the constituent yarn fineness was 700 dtex, the number of single yarns was 105, the single yarn fineness was 6.7 dtex, and the weave density was changed. The physical properties of the obtained airbag base fabric are shown in Table 1 below.

[0112] [Example 5] The coating material has a basis weight of 5 g / m ２ An airbag base fabric was produced in the same manner as in Example 1, except that the airbag base fabric was changed to the above. The physical properties of the obtained airbag base fabric are shown in Table 1 below.

[0113] [Example 6] The coating material has a basis weight of 30 g / m ２ An airbag base fabric was produced in the same manner as in Example 1, except that the airbag base fabric was changed to the above. The physical properties of the obtained airbag base fabric are shown in Table 2 below.

[0114] [Example 7] An airbag base fabric was produced in the same manner as in Example 1, except that the warp tension during weaving was changed to 0.2 cN / dtex and the warp tension during lamination was changed to 0 cN / dtex. The physical properties of the obtained airbag base fabric are shown in Table 2 below.

[0115] [Example 8] In the post-heating (heat setting), an airbag base fabric was produced in the same manner as in Example 1, except that a pin tenter was not used and the warp tension was changed to 0 cN / dtex. The physical properties of the obtained airbag base fabric are shown in Table 2 below.

[0116] [Example 9] An airbag base fabric was produced in the same manner as in Example 1, except that the warp tension during weaving was 0.2 cN / dtex, flattening treatment by calendaring was not performed, and the warp tension during lamination was changed to 0.05 cN / dtex. The physical properties of the obtained airbag base fabric are shown in Table 2 below.

[0117] [Example 10] An airbag fabric was produced in the same manner as in Example 1, except that a PET raw yarn having a fineness of 550 dtex and a number of single yarns of 144 was used. The physical properties of the obtained airbag fabric are shown in Table 2 below.

[0118] [Reference Example] An airbag base fabric was produced in the same manner as in Example 1, except that the number of single yarns was changed to 216, the single yarn fineness was changed to 2.3 dtex, and the CF was changed by adjusting the weave density. The physical properties of the obtained airbag base fabric are shown in Table 2 below.

[0119] [Comparative Example 1] The number of single yarns was 72, the single yarn fineness was 6.8 dtex, and the basis weight of the covering material was 40 g / m ２ An airbag base fabric was produced in the same manner as in Example 1, except that the airbag base fabric was changed to the above. The physical properties of the obtained airbag base fabric are shown in Table 3 below.

[0120] [Comparative Example 2] The warp tension during weaving was 0.2 cN / dtex, the warp tension during lamination was 0 cN / dtex, and a pin tenter was not used in post-heating (heat setting), the warp tension was 0 cN / dtex, and the basis weight of the covering agent was 20 g / m ２ An airbag base fabric was produced in the same manner as in Example 1, except that the airbag base fabric was changed to the above. The physical properties of the obtained airbag base fabric are shown in Table 3 below.

[0121] [Comparative Example 3] An airbag base fabric was produced in the same manner as in Example 1, except that the flattening treatment by calendaring was not performed, the warp tension during lamination was 0.05 cN / dtex, and post-heating (heat setting) was not performed. The physical properties of the obtained airbag base fabric are shown in Table 3 below.

[0122] [Comparative Example 4] The warp tension during lamination was 0.15 cN / dtex, the film was changed to silicone, and the basis weight of the coating material was 25 g / m ２ An airbag base fabric was produced in the same manner as in Example 1, except that the airbag base fabric was changed to the above. The physical properties of the obtained airbag base fabric are shown in Table 3 below.

[0123] [Comparative Example 5] An airbag base fabric was produced in the same manner as in Example 1, except that the constituent yarn fineness was changed to 350 dtex, the single yarn fineness was changed to 2.6 dtex, and the CF was changed by adjusting the weave density. The physical properties of the obtained airbag base fabric are shown in Table 3 below.

[0124] [Comparative Example 6] The constituent yarn fineness was changed to 350 dtex, the single yarn fineness was changed to 2.6 dtex, the CF was changed by adjusting the weave density, the film was changed to silicone, and the basis weight of the coating agent was changed to 20 g / m ２An airbag base fabric was produced in the same manner as in Example 1, except that the airbag base fabric was changed to the above. The physical properties of the obtained airbag base fabric are shown in Table 3 below.

[0125]

[0126]

[0127]

[0128] If an airbag cushion is produced from the airbag fabric according to the present invention, it will be a flexible, lightweight, and easy-to-store airbag cushion that is energy efficient in expanding the airbag and is less likely to tear at the seams even under high pressure. Furthermore, it will be an airbag cushion that is resistant to abrasion of the cushion and has a low environmental impact, and is particularly suitable for use in pedestrian airbags and far side airbags, which require good storage properties.

[0129] DESCRIPTION OF SYMBOLS 1 Airbag base fabric 2 Covering (film) 3 Cross section of warp or weft yarns constituting woven fabric 4 Measuring element 5 Measuring base 6 Base fabric 7 Bending portion of base fabric 8 Hexagon socket head cap screw (M6) 9 Washer 10 Upper silicone packing (1.0 mm thick, inner diameter 116 mm, outer diameter 150 mm, hardness A50°) 11 Sample (diameter 130 mm) 12 Lower silicone packing (1.0 mm thick, inner diameter 116 mm, outer diameter 150 mm, hardness A50°) 13 O-ring (wire diameter 5.7 mm, inner diameter 104.6 mm, outer diameter 136 mm, material NBR, hardness A70°) 14 Volume adjustment aluminum rod 15 Pressure sensor 16 Flow rate sensor 17 Digital flow rate regulator 18 Data logger 19 PC 20 Burst test device 21 Nitrogen cylinder 22 Pressure valve 23 Pressure tank 24 Solenoid valve 25 Fixing band 26 Gas outlet 27 Circular stitching 28 Airbag cushion 29 PC 30 Data logger 31 Pressure detection unit 32 Air tube 33 Pressure port mounting unit 34 Peripheral stitching A-A' Cross section cut so that the cut surface includes both the diameter yarns and the weft yarns B-B' Cross section cut so that the cut surface includes only the diameter yarns a Left end of the cross section of one yarn (aggregate of multifilaments) on the film adhesive surface b Lower end of the same a' Right end of the same P Length of the arc passing through the three points a, b, and a' Q Length of the straight line segment a-a'

Claims

1. An airbag fabric in which at least one side of a woven fabric, both of which have warp and weft yarns made of multifilament yarns, is covered with a film, and the bias / parallel tensile strength ratio of the airbag fabric is 0.2 or more and 0.6 or less.

2. The airbag fabric according to claim 1, wherein the cover factor (CF) of the woven fabric is 1700 or more and 2000 or less.

3. The high-pressure air permeability of the airbag fabric under a differential pressure of 100 kPa is 0.10 L / cm ２ The airbag fabric according to claim 1, wherein the airbag fabric has a stretchability of 1 / 2 s or less.

4. The airbag fabric according to claim 1, wherein the total fineness of the yarns constituting the woven fabric is 200 dtex or more and 900 dtex or less.

5. The airbag fabric according to claim 4, wherein the single yarn fineness of the yarn constituting the woven fabric is 1 dtex or more and 7 dtex or less.

6. The airbag fabric according to claim 1, wherein the thickness of the coating is 1 μm or more and 20 μm or less.

7. The weight of the airbag fabric is 100 g / m ２ More than 300g / m ２ The airbag fabric according to claim 1, wherein:

8. The airbag fabric according to claim 1, wherein the bias tensile strength of the airbag fabric is 300 N / 2 cm or more and 500 N / 2 cm or less.

9. The tear strength characteristic value (T value) of the airbag fabric in the warp and weft directions of the fabric is 1.6 N / (g / m ２ ) or more 5.0N / (g / m ２ 2. The airbag fabric according to claim 1, wherein the thickness is 100 mm or less.

10. The breaking strength characteristic value (F value) of the airbag fabric in the warp and weft directions of the fabric is 8.0 N / (g / m ２ ) or more 20.0N / (g / m ２ 2. The airbag fabric according to claim 1, wherein the thickness is 100 mm or less.

11. The slip resistance value (E value) of the airbag fabric in the warp and weft directions of the fabric is 1.0 N / (g / m ２ ) or more 10.0N / (g / m ２ 2. The airbag fabric according to claim 1, wherein the thickness is 100 mm or less.

12. The airbag fabric according to claim 1, wherein the stiffness characteristic values ​​(S values) of the airbag fabric in both warp and weft directions of the fabric are 2.0 N or more and 9.0 N or less.

13. An airbag fabric as described in claim 1, wherein the thickness of the coating is 1 μm or more and 20 μm or less, and the sum of the cut surface fiber meandering rates in the warp and weft directions of the fabric is 5.0% or more and 12.0% or less.

14. The airbag fabric according to claim 1, wherein the fiber meandering rate of the cut surface in the warp and weft directions of the fabric is 2.0% or more and 7.0% or less.

15. The airbag fabric according to claim 1, wherein the sum of the crimp rates in the warp and weft directions of the fabric is 5.0% or more and 12.0% or less.

16. The airbag fabric according to claim 15, wherein the crimp rate in both warp and weft directions of the fabric is 2.0% or more and 7.0% or less.

17. The airbag fabric according to claim 1, wherein the coating-single yarn contact ratio in both warp and weft directions of the fabric is 20% or more and 40% or less.

18. The tear strength characteristic value (T value) of the airbag fabric in the warp and weft directions of the fabric is 1.6 N / (g / m ２ ) or more 5.0N / (g / m ２ 2. The airbag fabric according to claim 1, wherein the thickness is 100 mm or less.

19. The airbag fabric according to claim 1, wherein the tear strength (T value) of the airbag fabric in both warp and weft directions of the fabric is 300N or more and 800N or less.

20. An airbag comprising the airbag fabric according to any one of claims 1 to 19.

21. A method for producing an airbag fabric according to any one of claims 1 to 19, comprising the following steps: a laminating step of adhering a film to at least one surface of a woven fabric while applying tension to the fabric in the warp and / or weft directions; and a heat treatment step of heating the resulting film-laminated woven fabric at a temperature of 150°C or higher while applying tension to the fabric in the warp and / or weft directions.

22. A method for manufacturing an airbag fabric as described in claim 21, wherein the ratio of the tear strength of the woven fabric laminated with the film after the heat treatment process to the tear strength of the woven fabric subjected to the lamination process is 100% or more and 500% or less in both the warp and weft directions of the woven fabric.

23. A method for manufacturing an airbag fabric as described in claim 21 or 22, wherein the ratio of the slippage resistance of the woven fabric laminated with the film after the heat treatment process to the slippage resistance of the woven fabric subjected to the lamination process is 200% or more and 2000% or less in both the warp and weft directions of the woven fabric.

24. An airbag fabric in which at least one side of a woven fabric, both of which have warp and weft threads made of multifilament yarns, is covered with a film, the cover factor (CF) of the woven fabric being 1700 or more and 2000 or less, the thickness of the covering being 1 μm or more and 20 μm or less, and the sum of the fiber meandering rates of the cut surface in the warp and weft directions of the woven fabric being 5.0% or more and 12.0% or less.

25. An airbag fabric in which at least one side of a woven fabric, both of which have warp and weft yarns made of multifilament yarns, is covered with a film, the cover factor (CF) of the woven fabric being 1700 or more and 2000 or less, and the cover-single yarn contact ratio in both the warp and weft directions of the woven fabric being 20% ​​or more and 40% or less.

26. An airbag fabric in which at least one side of a woven fabric, both of which warp and weft are made of multifilament yarns, is covered with a film, and the tear strength characteristic value (T value) of the airbag fabric in both the warp and weft directions of the woven fabric is 1.6 N / (g / m ２ ) or more 5.0N / (g / m ２ ) The airbag base fabric is as follows.

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