Airbag with reinforced tether stitching

Abstract

Provided is an airbag such as a pedestrian airbag that has a comparatively large size so as to cover the entire vehicle width and that regulates an inflation thickness with a tether connecting opposing panels, the airbag thinning the panels and being lightweight and small capacity for storage, while suppressing breakage during airbag deployment at a sewn part between the panels and the tether. The present invention relates to an airbag having a bag body in which a pair of base fabric panels are sewn at the outer peripheral edge thereof, and a tether fabric that is sewn on the pair of base fabric panels inside the bag body so as to make it possible to regulate the distance between the pair of base fabric panels during inflation of the bag body, the airbag being characterized in that the base fabric panels and the tether fabric are sewn together with a reinforcing fabric on the outside of the bag body, and the reinforcing fabric and the base fabric panels are in a laminated form fixed by an adhesive layer having an adhesive agent. The airbag is preferably a pedestrian airbag.

Description

[Technical Field]

[0001] The present invention relates to an airbag used in an airbag device mounted on a vehicle. More specifically, the present invention relates to an airbag in which opposing base fabric panels are sewn together with a tether fabric to maintain a predetermined thickness of the airbag when inflated, and the sewn portions of the tether fabric are reinforced to prevent breakage. [Background technology]

[0002] An airbag system installed in a vehicle consists of an airbag module (device), a sensor, and an operation control device. The airbag module consists of an airbag container, an inflator gas generator, and an airbag cushion. Here, the airbag cushion is simply referred to as an airbag. Conventionally, airbags are configured such that the distance between opposing panels is determined by the tether connecting opposing panels when the thickness of the airbag at full inflation is determined. Patent Document 1 listed below discloses a pedestrian airbag in which the tether between opposing panels is relatively wide, and the tether supports the inflation and deployment structure of the airbag to widely cover the automobile hood cover (bonnet). However, Patent Document 1 does not specifically describe the type of stitching between the panel and the tether, much less the strength of the stitching. Furthermore, in the airbag described in Patent Document 1, the thickness of the airbag is restricted by the tether when gas inflates, so excessive force acts on the tether stitching, which may cause the bag to tear near the stitching.

[0003] The following Patent Document 2 proposes that in order to reinforce the base fabric near the seams, a reinforcing fabric is placed on the outer surface of the base fabric, and the reinforcing fabric is sewn to the base fabric with a seam (single stitching), while one end of a connecting fabric is sewn to both the reinforcing fabric and the base fabric with a seam (co-stitching) (see Figure 3 of the same document). However, although Patent Document 2 teaches that the stress generated at the joint stitching when the airbag is inflated is distributed between the reinforcing fabric and the base fabric, the reinforcing fabric is fixed to the base fabric by sewing, which causes problems due to the stitching being too steep.Furthermore, there is no mention whatsoever of the relationship between the strength of independently sewn seams and jointly sewn seams.

[0004] In the following Patent Document 3, in order to provide a pedestrian protection airbag in which the tether is less likely to break, it is proposed that when sewing the base fabric and the tether, the upper end of the tether is folded along the base fabric to form a horizontal folded portion and then sewn (see Figures 5 and 6 of the same document). However, Patent Document 3 does not describe sewing a reinforcing fabric to a base fabric when sewing a tether to the base fabric, or using an adhesive layer to fix the reinforcing fabric to the base fabric, and it does not teach adding a reinforcing fabric to bear the stress of the sewn area together with the base fabric and strengthen the sewn area. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-172170 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-148365 [Patent Document 3] Japanese Patent Application Publication No. 2019-34618 Summary of the Invention [Problem to be solved by the invention]

[0006] For example, pedestrian protection airbags must be large enough to cover the entire width of the vehicle and must be able to inflate rapidly to protect the human body. If gas is supplied from a single location, the cushion bag of the airbag will be subjected to a large load when it inflates, and depending on the shape and design, there is a risk that the bag may rupture. Furthermore, when attempts are made to make airbags lighter to further improve the energy efficiency of vehicles and to reduce storage volume by using thinner fabric panels for the airbag, conventional airbag configurations can cause the bag to rupture when inflated. Under these circumstances, the problem that the present invention aims to solve is to provide an airbag, for example, a pedestrian protection airbag, which is relatively large so as to cover the entire width of a vehicle and whose inflation thickness is regulated by a tether connecting opposing panels, by making the panels thinner, making the airbag lightweight and requiring a small storage capacity, while suppressing rupture at the seam between the panel and the tether when the airbag is deployed. [Means for solving the problem]

[0007] That is, the original explanation is as follows: [1] An airbag having a bag body in which a pair of base fabric panels are sewn together at their outer peripheries, and a tether cloth sewn to the pair of base fabric panels inside the bag body so as to regulate the distance between the pair of base fabric panels when the bag body is inflated, The base fabric panel and the tether fabric are sewn together with a reinforcing fabric on the outside of the bag body, The airbag is characterized in that the reinforcing fabric and the base fabric panel are in a laminated form, fixed together with an adhesive layer of an adhesive. [2] The airbag according to [1], wherein the adhesive layer between the reinforcing fabric and the base fabric panel is a single layer or an intermittent pattern layer. [3] The airbag according to [2], wherein the adhesive coverage area ratio in the adhesive layer between the reinforcing fabric and the base fabric panel is 3% or more and 100% or less. [4] The airbag according to [2] or [3], wherein at least a portion of the intermittent pattern layer of the adhesive layer has a dotted pattern or a striped pattern. [5] The airbag according to any one of [1] to [3], wherein the adhesive of the adhesive layer is a tacky resin, a hot melt resin, or a curable resin. [6] The airbag according to any one of [1] to [5], wherein the adhesive layer is missing at the seam where the base fabric panel, the tether fabric, and the reinforcing fabric are sewn together. [7] The airbag according to any one of [1] to [6], wherein the reinforcing fabric and the base fabric panel are both plain weave fabrics, and the reinforcing fabric is biased and fixed to the base fabric panel in the warp and weft directions. [8] The airbag according to any one of [1] to [7], wherein the reinforcing fabric is sewn to the base fabric panel via the adhesive outside the seam allowance of the tether fabric with a seam strength lower than the seam strength between the reinforcing fabric, the base fabric panel, and the tether fabric. [9] The airbag described in [8], wherein the lower stitching strength than the stitching strength between the reinforcing fabric, the base fabric panel, and the tether fabric is due to the strength of the stitching thread, the fineness of the stitching thread, or a reduced number of stitches used in stitching.

[10] The airbag according to any one of [1] to [9], wherein the weave fineness of the reinforcing fabric {the value obtained by multiplying the weave fineness (dtex) by the weave density (counts / 2.54 cm) and adding the results in the warp and weft directions} is 1.1 times or more and 1.6 times or less the weave fineness of the base fabric panel.

[11] The airbag according to any one of [1] to

[10] , wherein the weave fineness of the tether fabric {the value obtained by multiplying the weave fineness (dtex) by the weave density (counts / 2.54 cm) and adding the results in the warp and weft directions} is 1.1 times or more and 1.6 times or less the weave fineness of the base fabric panel.

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

[11] , wherein the base fabric panel and the tether fabric are sewn together together with a reinforcing fabric fixed to the base fabric panel with adhesive on the outside of the bag body, and a tether reinforcing fabric arranged outside the seam allowance of the tether fabric on the inside of the bag body.

[13] The airbag according to

[12] , wherein the seam of the tether cloth and the tether reinforcing cloth are fixed with an adhesive.

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

[13] , wherein the seam allowance of the tether cloth is folded back and sewn.

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

[14] , wherein the fineness of the yarn constituting the base fabric panel is 200 dtex or more and 400 dtex or less.

[16] The airbag according to any one of [1] to

[15] , wherein the airbag is a pedestrian protection airbag. [Effects of the Invention]

[0008] According to the airbag of the present invention, for example, in an airbag such as a pedestrian protection airbag, which is relatively large so as to cover the entire width of a vehicle and in which the inflation thickness is regulated by a tether connecting opposing panels, it is possible to provide an airbag in which the panels are made thin, making the airbag lightweight and requiring a small storage capacity, while suppressing rupture at the seam between the panel and the tether when the airbag is deployed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of aspect 1 of an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of aspect 2 of an embodiment of the present invention. [Figure 3] FIG. 1 is a cross-sectional view of aspect 3 of an embodiment of the present invention. [Figure 4] FIG. 1 is a cross-sectional view of aspect 4 of an embodiment of the present invention. [Figure 5] FIG. 1 is a cross-sectional view of aspect 5 of an embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view of aspect 6 of an embodiment of the present invention. [Figure 7] FIG. 10 is a cross-sectional view of aspect 7 of an embodiment of the present invention. [Figure 8] FIG. 10 is a cross-sectional view of aspect 8 of an embodiment of the present invention. [Figure 9] FIG. 2 is an explanatory diagram showing an outline of the sample shape (before sewing) in the examples and comparative examples. [Figure 10] FIG. 1 is an explanatory diagram showing an outline of the sample shape (after sewing) in Examples and Comparative Examples. [Figure 11] FIG. 2 is an explanatory diagram showing an outline of a method for measuring stitching strength in Examples and Comparative Examples. [Figure 12] FIG. 10 is an explanatory diagram showing an outline of the sample shape (after sewing) in Comparative Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail. One embodiment of the present invention is an airbag having a bag body in which a pair of base fabric panels are sewn together at the outer periphery of an inflation chamber in the bag body, and a tether cloth sewn to the pair of base fabric panels inside the bag body so as to regulate the distance between the pair of base fabric panels when the bag body is inflated, wherein the base fabric panels and the tether cloth are sewn together with a reinforcing fabric on the outside of the bag body, and the reinforcing fabric and the base fabric panels are in a laminated form fixed together with an adhesive layer.

[0011] In the prior art, for example, a reinforcing fabric for panel reinforcement is sewn (sewing) to a (base fabric) panel, and a tether is sewn to the reinforced portion (see Figure 2 of Patent Document 2). In contrast, in the present embodiment, a reinforcing fabric for panel reinforcement is attached and fixed to the base fabric panel with adhesive (from the outside of the base fabric panel), and a tether (cloth) is sewn to the reinforced portion (see Figure 1). By attaching a reinforcing fabric for panel reinforcement to the panel and sewing a tether to the reinforced portion, it is possible to avoid an increase in the amount of stitching around the reinforced portion or dense stitching, improving the workability of the reinforcing fabric attachment process, making it easier to fold and store. Furthermore, it is not hindered by rough stitching, and the reinforcing effect is actually enhanced. In the present embodiment, by eliminating the area of ​​reinforcing fabric required as a seam allowance in the prior art when using reinforcing fabric, it is possible to reduce the amount of reinforcing fabric used.

[0012] For example, in the case of a pedestrian protection airbag, when it inflates and deploys, the gas pressure applies tension to the base fabric panel and tether fabric. As the airbag expands from its folded state, rupturing the airbag case cover (container) and deploying, there is a risk of the bag tearing before it is fully inflated and ready to protect pedestrians. The tear occurs at the seam where the tether fabric is attached. In particular, when the fabric of the panel is made thinner to reduce weight, the tether fabric attachment point can become the starting point of the tear, causing damage to the base fabric panel. In this embodiment, when sewing the tether cloth to the base fabric panel, the reinforcing cloth is attached to the outside of the base fabric panel (fixed with adhesive) and then sewn together. Therefore, even if the fabric of the base fabric panel is made thinner to reduce weight, the reinforcing portion consisting of the base fabric panel and the reinforcing cloth absorbs the stress concentration at the seam, preventing the bag from rupturing. The airbag as a whole is lightweight, while preventing gas pressure rupture, achieving a high ultimate pressure and fulfilling its function of protecting the human body. In addition, the process of attaching the reinforcing cloth to the base fabric panel by attaching it is easy to work with. Since there are fewer stitches, the airbag is easier to fold and store, deployment is not hindered by the stitches, and the reinforcing effect is actually enhanced by the unity of the base fabric panel and the reinforcing cloth. The reinforcing fabric should be located on the opposite side of the base fabric panel where the tether fabric is sewn. In other words, the reinforcing fabric should be located on the outermost side of the airbag so that it can support the stress concentration at the seams due to gas pressure.

[0013] The adhesive that constitutes the adhesive layer used to attach and fix the reinforcing fabric to the base fabric panel is not particularly limited, but various adhesive resins and adhesive resins (pressure-sensitive adhesives) can be used. When assembling the airbag, applying an adhesive resin or adhesive resin to the reinforcing fabric and then attaching and fixing the panel and reinforcing fabric also makes the assembly process easier. If adhesive resin is used, bonding the base fabric panel and reinforcing fabric is easy, as it only requires pressing the two together. Adhesive resins are resins that are adhesive at room temperature (around 20°C), and examples include acrylic adhesives, urethane adhesives, and silicone adhesives. The main raw material for acrylic adhesives is butyl acrylate, but other adhesives include ethyl acrylate and 2-hexyl acrylate.

[0014] The adhesive resin may be a hot-melt resin that is solid at room temperature and has thermal melting properties, or a curable resin that hardens when heated. The hot melt resin may be a thermoplastic resin having a melting point of 80 to 200° C. Examples of the hot melt resin include polyamide, polyurethane, polyester, polypropylene, polyethylene, and modified ethylene vinyl acetate copolymer. Among the curable resins, examples of the thermally crosslinkable resin include those in which an epoxy-based crosslinking agent is added to acrylic or polyurethane, and those containing N-methylolacrylamide are particularly preferred.

[0015] The adhesive (laminating resin) may be applied in a thin layer to the base fabric panel and / or the reinforcing fabric. The adhesive layer may be a substantially uniform single layer (coverage area ratio 100%) or a layer with an intermittent pattern. The intermittent pattern may be, for example, a dotted pattern or a striped pattern. When the adhesive layer has an intermittent pattern, the coverage area ratio of the intermittent pattern of the adhesive layer to the reinforcing fabric may be 3% or more and 100% or less. In particular, to obtain the effect of reinforcing the sewn parts, a coverage area ratio of 5% or more is preferable, while from the perspective of ease of folding and flexibility of the sewn parts, a coverage area ratio of 60% or less is preferable.

[0016] The intermittent pattern layer is preferably arranged in the form of dots (points). The dot diameter can be, for example, 100 μm or more and 1500 μm or less. The number of dots can be, for example, 9 dots / (25.4×25.4 mm). 2 )) or more 2500(pcs / (25.4×25.4mm) 2)) or less. By applying the adhesive in a dot pattern, the adhesive joints are less likely to harden and do not interfere with the foldability of the airbag. The bonding resin may also be applied in a line (striped) pattern. In this case, for example, lines 0.5 mm to 3 mm wide may be provided at intervals of 0.5 mm to 3 mm. By applying the adhesive in a striped pattern, the adhesive joints are less likely to harden and do not interfere with the foldability of the airbag. In particular, if the line direction matches the folding line, the airbag can be folded flexibly. In particular, by applying the adhesive in a manner that avoids the areas where the tether fabric, base fabric panel, and reinforcing fabric are sewn together, it is possible to avoid deterioration of workability due to soiling of the sewing machine needle during the sewing process (see Figure 2).

[0017] When the laminating resin is arranged in a dotted or striped pattern, the area covered by the resin is 3% to 90% of the area of ​​the reinforcing fabric, preferably 5% to 60%. The amount of the laminating resin is 5 (g / m 2 ) or more 35 (g / m 2 ) or less, and preferably 10 (g / m 2 ) or more 30(g / m 2 ) is as follows. The laminating resin can be applied to the base fabric panel and / or reinforcing fabric by gravure coating or screen coating, or by transferring the laminating resin onto the base fabric panel and / or reinforcing fabric using a release paper. When the reinforcing fabric is attached to the base fabric panel in an intermittent pattern such as a dot or stripe pattern, or by partial bonding in which only specific locations are bonded, the folding process is improved. Furthermore, by using a thermoplastic material to attach the reinforcing fabric to the panel and fixing it to the panel at a relatively low temperature before sewing, the airbag sewing can be completed without impairing the physical properties of the panel. Furthermore, by attaching the reinforcing fabric in an intermittent pattern such as a dot pattern, the integral portion of the panel and the reinforcing fabric remains flexible, preventing impairing foldability. If the attachment and fixing portion is positioned to avoid the sewing line, the adhesive does not soil the sewing needle, and there is no fluctuation in sewing needle resistance, resulting in a stable sewing process. Interference with folding and storage is avoided, and rough stitching reduces the obstruction to deployment.

[0018] When bonding a base fabric panel and a reinforcing fabric, if both the reinforcing fabric and the base fabric panel are plain weave fabrics, the reinforcing fabric can be fixed to the base fabric panel in a biased manner in the warp and weft directions (not shown). "Biased" means that the warp threads of the reinforcing fabric and the warp or weft threads of the base fabric panel are not parallel, but are tilted at approximately 45 degrees. This allows the reinforcing fabric and the base fabric panel to mutually absorb the force applied to the seam when the airbag deploys, increasing the strength of the co-stitched seam.

[0019] When bonding a base fabric panel and a reinforcing fabric together, both the base fabric panel and the reinforcing fabric can be single-sided coated fabrics, but it is preferable to bond the uncoated surfaces together to ensure flexibility and adhesive strength at the bonded area (not shown).

[0020] As mentioned above, if a reinforcing fabric is attached to the base fabric panel for reinforcement and a tether is sewn together with the reinforced area, the workability of the process of attaching the reinforcing fabric improves, the bag becomes easier to fold and store, and the obstacles to deployment caused by rough stitching are eliminated, and the reinforcing effect is actually enhanced. On the other hand, minimal stitching (sewing) may be performed to secure the reinforcing fabric (see Figure 3). Alternatively, a reinforcing fabric may be attached to a base fabric panel for reinforcement, followed by sewing the periphery of the reinforcing fabric and then co-sewing a tether to the reinforced portion for finishing. This is because sewing the reinforcing fabric to the panel mostly around its periphery can stabilize the sewing process. The stitching of the reinforcing fabric to the base fabric panel at this periphery is different from the co-sewing that sews the reinforcing fabric and the tether fabric together, and is preferably weaker than this. The stitching strength at this periphery, which is lower than the co-sewing strength between the reinforcing fabric, the base fabric panel, and the tether fabric, can be achieved by using a stronger stitch, a smaller fineness of the stitching, or a smaller number of stitches. Sewing the reinforcing fabric to the base fabric panel at this periphery prevents the co-sewing from becoming the starting point for airbag destruction by breaking the stitching when force is applied during deployment. Furthermore, such stitching at the outer periphery allows for easy folding and storage, and reduces the interference with airbag deployment caused by rough stitching. By sewing roughly the periphery of the reinforcing fabric to the base fabric panel, the process up to the sewing stage becomes more stable. The stitching between the reinforcing fabric and the base fabric panel at the periphery is performed with a weaker stitch than the stitching between the reinforcing fabric, the base fabric panel, and the tether fabric. This allows the thread to break in the former first, preventing the airbag from breaking in the latter. This also prevents interference with folding and storage, and reduces the risk of deployment being hindered by rough stitching.

[0021] The reinforcing fabric is intended to compensate for the lack of strength of the base fabric panel (woven fabric), and preferably compensates for the thickness of the base fabric (woven fabric) (see Figure 4). The weave fineness (dtex / 2.54 cm) of the reinforcing fabric is preferably 0.65 to 1.6 times the weave fineness of the base fabric panel, more preferably 0.9 to 1.6 times, and even more preferably 1.1 to 1.6 times. If the weave fineness (dtex / 2.54 cm) of the reinforcing fabric is 1.6 times or less the weave fineness of the base fabric panel, packability and weight reduction are not impaired. Here, the weave fineness is the value obtained by multiplying the fineness (dtex) by the weave density (counts / 2.54 cm) of the woven fabric constituting the base fabric panel or tether cloth, and adding the result in the warp and weft directions. A higher weave fineness results in a thicker fabric and a larger weight per unit area. By making the weave fineness of the reinforcing fabric larger than that of the base fabric panel (by 1.1 times or more), it is possible to effectively prevent the base fabric panel from being destroyed at the seams. When the base fabric panel is inflated by gas, the thickness of the airbag is restricted by the tether fabric, so a large force acts on the seams of the tether fabric. However, when force acts on the base fabric panel via the sewing thread, the reinforcing fabric helps to withstand the force.

[0022] In particular, when the base fabric panel is made thinner by reducing the fineness of its constituent yarns, the portion that bears the force of airbag inflation and deployment is mainly the reinforcing fabric, rather than the base fabric panel, and the seams can withstand breakage. From the viewpoints of mechanical properties and packability, the fineness of the constituent yarns of the thinned base fabric panel is preferably 200 dtex or more and 400 dtex or less, and more preferably 200 dtex or more and 300 dtex or less.

[0023] The tensile breaking strength (N / cm) of the reinforcing fabric is preferably 0.9 times or more, more preferably 1.1 times or more, that of the panel. If it is 1.6 times or less, it is easily available as a woven fabric (not shown).

[0024] As shown in Figure 5, the weave fineness of the tether fabric (dtex / 2.54 cm) is preferably larger than the weave fineness of the base fabric panel, preferably 1.1 times or more, more preferably 1.2 times or more, and even more preferably 1.4 times or more. On the other hand, if the weave fineness of the tether fabric (dtex / 2.54 cm) is 1.6 times or less than the weave fineness of the base fabric panel, packability and weight reduction are not impaired.

[0025] As shown in Fig. 6, when the tether cloth is sewn to the panel, it is also preferable to sew a tether reinforcing cloth together. The weave fineness (dtex / 2.54 cm) of the tether reinforcing cloth is preferably larger than that of the base cloth panel. The tether reinforcing cloth is preferably attached so as to cover the seam allowance of the tether cloth from above. In this case, as shown in Fig. 7, the tether cloth and the tether reinforcing cloth can be fixed with an adhesive, similar to the above-mentioned reinforcing cloth and base cloth panel.

[0026] As shown in FIG. 8, it is also preferable to fold the tether fabric and sew it to the base fabric panel, since this strengthens the seam.

[0027] This embodiment is an airbag configured using a tether that restricts the thickness of a base fabric panel, and is particularly preferably an airbag for protecting pedestrians. [Example]

[0028] The present invention will be specifically described below with reference to examples and comparative examples. First, the materials used in the examples and comparative examples, and the methods for measuring physical properties will be described.

[0029] [Base fabric panel] The fabric used was a plain weave fabric woven using nylon 66 multifilament fibers as warp and weft yarns and coated with silicone resin. The total fineness of the yarns constituting the base fabric used was 235 dtex, the number of filaments was 72, the weave density of the base fabric panel was 72 threads / inch (2.54 cm), the weave fineness was 33,840 (dtex / 2.54 cm), and the amount of silicone resin coated was 17 g / m. 2 It was.

[0030] [Tether cloth] The fabric used was a plain weave fabric woven using nylon 66 multifilament fibers as the warp and weft, coated with silicone resin. The total fineness of the weaving yarns constituting the base fabric used was 470 dtex, the number of filaments was 136, the weave density of the tether fabric was 49 threads / inch (2.54 cm), and the weave fineness was 46,060 (dtex / 2.54 cm). The amount of silicone resin coated was 25 g / m 2 It was.

[0031] [Reinforcing fabric] The fabric used was a plain weave fabric woven using nylon 66 multifilament fibers as warp and weft yarns and coated with silicone resin. The total fineness of the yarns constituting the base fabric was 235 dtex, the number of filaments was 72, the weave density of the reinforcing fabric was 72 threads / inch, the weave fineness was 33,840 (dtex / 2.54 cm), and the amount of silicone resin coated was 17 g / m. 2 It was.

[0032] [Heat-melting film] CoPA1 (glass transition temperature Tg = 47 ° C, melting point Tm = 128 ° C) described in International Patent Application No. 2020 / 032032 was used as the adhesive (laminating resin) constituting the adhesive layer, and a 20 μm thick film was formed using this to form the adhesive layer.

[0033] [Adhesive] An acrylic adhesive described in JP 2008-254269 A was used as the adhesive (adhesive resin) and an intermittent pattern layer was formed on the reinforcing fabric as an adhesive layer using a gravure roll coater. The intermittent pattern layer had a dot pattern with a dot thickness of 30 μm, a dot diameter of 100 μm, a dot spacing of 150 μm, and an adhesive (coated) area ratio of 25%. Alternatively, the intermittent pattern layer had a stripe pattern with a stripe width of 2.0 mm, a stripe spacing of 0.8 mm, a stripe thickness of 40 μm, and an adhesive (coated) area ratio of 40%.

[0034] [Sutures] Gunze Ltd.'s sewing thread for airbags (total fineness 1880 dtex, nylon 66 multifilament fiber 940 dtex two-ply twist) was used for the upper and lower threads.

[0035] [sewing machine] The tether fabric and the base fabric panel were sewn together using a JUKI LU-2210W-7 sewing machine.

[0036] [Preparation of test specimens] As shown in the <Sample Shape> in Figure 9, the tether base fabric and the base fabric panel were each cut into strips along the grain of the base fabric, with a warp of 320 mm and a weft of 500 mm. The reinforcing fabric (also called a patch) was cut along the grain of the base fabric, with a warp of 300 mm and a weft of 30 mm. First, the reinforcing fabric was placed on the base fabric panel with the uncoated side facing each other, and they were glued or sewn together within the range of the fixing points (4b). Then, as shown in the <Sample Shape (After Tether Sewing)> in Figure 9, the three layers were layered together in the order of tether fabric → panel base fabric → reinforcing fabric, and sewn together. The co-sewing was performed by using the sewing machine with the same sewing thread to sew a straight line stitch (4a: tether sewing) at 50 stitches / 10 cm over a 270 mm central area in the width direction, with a seam allowance of 15 mm for the tether fabric. Three backstitches were added at the beginning and end of the stitching. Next, as shown in the <Sample shape (after sewing of the tether overlapping portion)> in Figure 10, in order to evaluate the mechanical properties of the sewn portion, the longitudinal ends of the base fabric panels were overlapped, the rectangular shape was formed into a loop, and the overlapping portion was sewn with three rows of straight line stitches (7a: sewing of the overlapping portion of the base fabric panel) in the base fabric warp direction at 35 stitches / 10 cm. The loop length was 320 mm around. The end of the tether fabric farthest from the straight seam (4a) was folded back, and the tether fabrics were sewn together midway between the straight seam (4a) and the folded part with three rows of straight stitches (7b: sewing the overlapping part of the tether fabric) in the warp direction of the base fabric at a stitch count of 35 stitches per 10 cm. The length from the folded part to the straight seam (4a) was 200 mm. Finally, it was confirmed that the overlapping parts of the base fabric panels and the tether fabrics were not tilted, and that the straight seams (4a) and the stitching of the overlapping parts (7a, 7b) were aligned in the warp direction of the base fabric. It was also confirmed that these were not misaligned to prevent uneven stress on the stitching during measurement, which would result in measurement errors.

[0037] (1) Measurement of sewing strength (N / cm) As shown in Figure 11 (<Jig Configuration>), a jig was attached to an A&D Tensilon universal material testing machine. The jig, which holds the test specimen by passing it through the loops of the base fabric panel and tether fabric, was attached to the Tensilon universal material testing machine. As shown in Figure 11 (<Sample Mounting Condition>), when the test specimen was attached to the machine and viewed from the side (the direction from which the thickness of the test specimen could be confirmed), the tether fabric was adjusted so that it was perpendicular to the base fabric panel (forming a T-shape). The stroke (the distance from the straight seam (4a: tether seam) to the point where the lower part of the tether fabric is fixed to the jig (the folded part)) was adjusted to 200–400 mm. Measurements were performed at a pulling speed of 300 mm / min. The maximum strength at break was calculated as the seam strength (N), and this value was divided by the length of the straight seam to calculate the seam strength (N / cm).

[0038] (2) Measurement of the thickness (mm) of the folded tether The base fabric panel and tether fabric of the test specimen prepared as described above were cut to fit the size of the protective fabric, resulting in a 300 mm x 30 mm sample. The cut sample was folded in half perpendicular to the straight seam (4a), and then folded in half again perpendicular to the fold to create a quartered sample. The folded portion of the sample was placed under a 150 mm x 15 mm plate, and a load of 1 kg was applied to the plate and the sample for 30 seconds. The sample thickness at the four corners of the plate was then measured with a vernier caliper, and the average of the four measurements was used as the bending thickness of the seam.

[0039] (3) Flatness after pressing into quarters A load of 5 kg in total was applied to the sample, prepared in the same manner as in the measurement of the thickness (mm) of the folded tether portion, for 30 seconds. After that, it was checked whether any marks other than the folds remained on the base fabric of the sample.

[0040] (4) Reinforcement fabric utilization rate (N / cm 2 ) The stitching strength (N) of the test specimen was calculated by dividing the area (cm 2 ) and the reinforcing fabric utilization rate (N / cm 2 ) was decided.

[0041] (5) Sewing time The sewing time was measured from the time required to cut sample pieces from the sample fabric to the time required to sew the evaluation samples. The time required for three workers to finish three test pieces for each sewing strength evaluation was measured. The average of the results was taken as the sewing time and expressed as an index with Comparative Example 3 as the reference of 100. However, in Examples 1 to 4, the heat-melt film of the reinforcing fabric was prepared by cutting it into the required shape in advance. In addition, in Examples 5 and 6, the adhesive of the reinforcing fabric was prepared by cutting a base fabric, on which the required pattern had been applied in advance using a coater, into the required shape.

[0042] [Examples 1 to 6, Comparative Examples 1 to 6] Test pieces were prepared having the reinforcing fabric and its fixing method and location shown in Table 1. The fixing locations shown in Table 1 indicate the positions of sewing and / or bonding performed in the range of fixing location (4b) in Figure 9 for each Example or Comparative Example, with the solid line indicating the outer edge of the reinforcing fabric, the gray hatching indicating the bonding area, and the dashed line indicating the sewing location. In Examples 1 to 4 and Comparative Example 6, the reinforcing fabric was placed on top of the base fabric panel, offset by 100 mm in the weft direction, with the uncoated surfaces facing each other. A hot-melt film was inserted between the panels and heat-pressed at 190°C for 5 seconds to bond the base fabric panel and the reinforcing fabric. The positions where the hot-melt film was inserted are indicated by gray hatching in the fixing positions in Table 1. In Examples 2 to 4, partial bonding was performed on a portion of the inside periphery of the reinforcing fabric. The base fabric panel with the reinforcing fabric bonded to it was placed on top of the tether fabric, offset by 100 mm in the weft direction, and the panels were arranged so that the ends of the tether fabric and the reinforcing fabric were aligned, resulting in a three-layer stack in the order of tether fabric → base fabric panel → reinforcing fabric.

[0043] In Examples 5 and 6, the reinforcing fabric with adhesive attached was attached to the uncoated surface of the base fabric panel. The adhesive attachment position is indicated by gray hatching at the fixing point in Table 1. The base fabric panel with the reinforcing fabric attached was placed on top of the tether fabric, offset by 100 mm in the weft direction, and arranged so that the ends of the tether fabric and the reinforcing fabric were aligned, resulting in a three-layer stack in the order of tether fabric → base fabric panel → reinforcing fabric.

[0044] In Comparative Example 1, no reinforcing fabric was used, and two layers were sewn together in the order of tether fabric and base fabric panel. In Comparative Example 2, no adhesive was used, and three layers were sewn together in the order of tether fabric, base fabric panel, and reinforcing fabric. In Comparative Example 3, the reinforcing fabric size was 320 mm x 50 mm, and no adhesive was used. The base fabric panel and reinforcing fabric were sewn together along the outer edge of the reinforcing fabric with a seam allowance of 10 mm. Three layers were then layered in the order of tether fabric → base fabric panel → reinforcing fabric, and the tether fabric was sewn together with a seam allowance of 25 mm. In Comparative Example 4, no adhesive was used, and sewing was performed to secure the base fabric panel and reinforcing fabric along the outer edge of the reinforcing fabric with a seam allowance of 3 mm, and then the three layers were sewn together in the order of tether fabric → base fabric panel → reinforcing fabric. In Comparative Example 5, no adhesive was used, and sewing was performed to secure the base fabric panel and reinforcing fabric along the outer edge of the reinforcing fabric with a seam allowance of 10 mm, and then the three layers were sewn together in the order of tether fabric → base fabric panel → reinforcing fabric. In Comparative Example 6, as shown in Figure 12, the tether cloth size was 270 mm warp x 500 mm weft, and instead of sewing to fasten the base fabric panel and reinforcing cloth, a 270 mm long slit (4c) was made in the base fabric panel and the tether cloth was inserted into the slit. The length of the tether cloth inserted into the slit was 15 mm, and the end of the tether cloth inserted into the base fabric panel was positioned so that it was in close contact with one half of the base fabric panel without folding, and the reinforcing cloth was then layered on top of it with the uncoated sides facing each other and bonded together, resulting in a three-layer stack in the order of tether cloth → base fabric panel → reinforcing cloth.

[0045] The above-mentioned sewing strength (N / cm), thickness of the tether part folded in four (mm), flatness after pressing in four, and reinforcing fabric utilization rate (N / cm 2 The results are shown in Table 1 below.

[0046] [Table 1] [Industrial Applicability]

[0047] The airbag according to the present invention can be used in, for example, pedestrian airbags, which are relatively large and cover the entire width of a vehicle, and in which the inflation thickness is restricted by tethers connecting opposing panels, by making the panels thinner, resulting in a lightweight airbag with a small storage volume, while suppressing rupture at the seams between the panels and the tethers when the airbag is deployed. Therefore, the airbag according to the present invention can be widely used in airbag devices for vehicles, including aircraft, ships, and automobiles. [Explanation of symbols]

[0048] 1 Tether Cloth 2 base fabric panels 3 Reinforcement fabric 4. Adhesive (between the reinforcing fabric and the base fabric panel) 5. Suturing (co-stitching) 5' stitching (auxiliary stitching, between reinforcement fabric and base fabric panel) 6 Tether reinforcement fabric 7 Adhesive (between tether reinforcement fabric and base fabric panel) 4a Tether stitching (see Figures 9-12) 4b Fixing points of base fabric panel and reinforcing fabric (see Figures 9-11) 4c Cutout of base fabric panel (insertion point for tether fabric, see Figure 12) 7a Sewing overlapping parts of base fabric panels (see Figures 9-12) 7b Sewing the overlapping part of the tether fabric (see Figures 9 to 12) 8 strokes (see Figure 11)

Claims

1. An airbag having a bag body in which a pair of base fabric panels are sewn together at their outer peripheries, and a tether cloth sewn to the pair of base fabric panels inside the bag body so as to regulate the distance between the pair of base fabric panels when the bag body is inflated, The base fabric panel and the tether fabric are sewn together with a reinforcing fabric on the outside of the bag body, The airbag is characterized in that the reinforcing fabric and the base fabric panel are in a laminated form fixed with an adhesive layer, and the adhesive layer is missing at the seam where the base fabric panel, the tether fabric, and the reinforcing fabric are sewn together.

2. 2. The airbag of claim 1, wherein the adhesive layer between the reinforcing fabric and the base fabric panel is a single layer or an intermittent patterned layer.

3. 3. The airbag according to claim 2, wherein a coverage area ratio of the adhesive in the adhesive layer between the reinforcing fabric and the base fabric panel is 3% or more and 100% or less.

4. 4. The airbag according to claim 2, wherein at least a portion of the intermittent pattern layer of the adhesive layer has a dotted pattern or a striped pattern.

5. 3. The airbag according to claim 1, wherein the adhesive of the adhesive layer is a tacky resin, a hot melt resin, or a curable resin.

6. 3. The airbag according to claim 1, wherein the reinforcing fabric and the base fabric panel are both plain weave fabrics, and the reinforcing fabric is biased and fixed to the base fabric panel in the warp and weft directions.

7. 3. The airbag according to claim 1, wherein the reinforcing fabric is sewn to the base fabric panel via the adhesive outside the seam allowance of the tether fabric with a seam strength lower than a seam strength between the reinforcing fabric, the base fabric panel, and the tether fabric.

8. 8. The airbag according to claim 7, wherein the lower seam strength than the seam strength between the reinforcing fabric, the base fabric panel, and the tether fabric is achieved by reducing the strength of the seam thread, the fineness of the seam thread, or the number of stitches used in the seam.

9. 3. The airbag according to claim 1, wherein the weave fineness of the reinforcing fabric (the value obtained by multiplying the weave fineness (dtex) by the weave density (counts / 2.54 cm) and adding the results in the warp and weft directions) is 1.1 to 1.6 times the weave fineness of the base fabric panel.

10. 3. The airbag according to claim 1, wherein the weave fineness of the tether fabric (the value obtained by multiplying the weave fineness (dtex) by the weave density (counts / 2.54 cm) and adding the results in the warp and weft directions) is 1.1 to 1.6 times the weave fineness of the base fabric panel.

11. 3. The airbag according to claim 1, wherein the base fabric panel and the tether fabric are sewn together together with a reinforcing fabric fixed to the base fabric panel by adhesive on the outside of the bag body, and a tether reinforcing fabric disposed on the outside of the seam allowance of the tether fabric on the inside of the bag body.

12. The airbag according to claim 11, wherein the seam of the tether fabric and the tether reinforcing fabric are fixed together with an adhesive.

13. 3. The airbag according to claim 1, wherein the seam margin of the tether cloth is folded back and sewn.

14. 3. The airbag according to claim 1, wherein the fineness of the yarn constituting the base fabric panel is 200 dtex or more and 400 dtex or less.

15. 3. The airbag according to claim 1, wherein the airbag is a pedestrian protection airbag.

16. An airbag having a bag body in which a pair of base fabric panels are sewn together at their outer peripheries, and a tether cloth sewn to the pair of base fabric panels inside the bag body so as to regulate the distance between the pair of base fabric panels when the bag body is inflated, The base fabric panel and the tether fabric are sewn together with a reinforcing fabric on the outside of the bag body, the reinforcing fabric and the base fabric panel are in a laminated form, fixed together with an adhesive layer of an adhesive, and the weave fineness of the reinforcing fabric (the value obtained by multiplying the fineness (dtex) by the weave density (counts / 2.54 cm) and adding the results in the warp and weft directions) is 1.1 to 1.6 times the weave fineness of the base fabric panel.

17. An airbag having a bag body in which a pair of base fabric panels are sewn together at their outer peripheries, and a tether cloth sewn to the pair of base fabric panels inside the bag body so as to regulate the distance between the pair of base fabric panels when the bag body is inflated, The base fabric panel and the tether fabric are sewn together with a reinforcing fabric on the outside of the bag body, the reinforcing fabric and the base fabric panel are in a laminated configuration, fixed together with an adhesive layer of an adhesive, and the weave fineness of the tether fabric (the value obtained by multiplying the fineness (dtex) by the weave density (counts / 2.54 cm) and adding the results in the warp and weft directions) is 1.1 to 1.6 times the weave fineness of the base fabric panel.

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