Airbag and method for manufacturing same

Abstract

[Problem] In order to reduce the leakage of inflation gas from a sewn portion of an airbag, the application of a coating material to the sewn portion has been carried out. There are techniques for applying a coating material from one side or from both sides, but there are problems in that when applying the coating material to the opposite side of the initially applied side, the initially applied coating material adheres to a base or flows away. [Solution] Such problems can be prevented by making the viscosity of a binder applied initially to a sewn portion on one side of a base fabric higher than the viscosity of a binder applied subsequently to the sewn portion on the opposite side of the base fabric.

Description

Airbag and its manufacturing method

[0001] The present invention relates to an airbag body and a method for manufacturing the same.

[0002] Following seatbelts as an automobile safety device, SRS airbags (seatbelt auxiliary airbags; hereafter referred to as airbags) became an optional feature in Japan in 1987. Initially, they were installed in the driver's seat. Over time, airbags became standard equipment in the driver's seat (steering wheel) and then in the passenger seat as well. When an automobile collision is detected by an acceleration sensor, airbags instantly inflate within 0.01 seconds. Once fully inflated and deployed, the gas is released and the airbag deflates. Through this series of actions, the airbag complements the seatbelt and reduces the impact of a collision between the driver and steering wheel, or the passenger seat occupant and dashboard. In addition to the airbags mentioned above, various types of airbags have been developed and put into practical use, including those that inflate between the side window and the head to reduce impact, those that inflate from the side of the seatback to the side or front of the occupant's body to protect the abdomen and chest, and pedestrian airbags that deploy over the hood of the vehicle in the event of a collision with a pedestrian to reduce the impact between the pedestrian and the hood.

[0003] When a vehicle collides with an obstacle ahead, the vehicle decelerates rapidly, but the occupants continue to move forward due to inertia. Therefore, even if the driver is wearing a seatbelt, there is a risk of their chest or head striking the steering wheel. This is why airbags are installed in steering wheels, as described above. After detecting a collision, the airbag fully inflates in approximately 0.03 seconds, supports the driver, absorbs energy, and then deflates. The entire process from airbag inflation to deflation after a vehicle collision is completed in approximately 0.2 seconds. If the airbag were to inflate too slowly, the driver would crash into the steering wheel. In order to ensure rapid inflation, in addition to the method of generating inflation gas, it is also important to ensure that the airbag is fully inflated during the inflation process by preventing more than a predetermined amount of inflation gas from leaking from unwanted locations. On the other hand, in the event of a side collision, there are side curtain airbags to prevent passengers (including the driver) from being injured or thrown out of the vehicle due to collision with the side window or the side of the passenger compartment, or contact with broken side window or the outside of the vehicle during a collision, and a center airbag installed between the driver's seat and the passenger seat to prevent the head from coming into contact with interior materials such as the door on the opposite side of the collision side (non-collision side).These are designed to remain inflated for a longer period of time than airbags in the steering wheel.

[0004] Patent Document 1 discloses a technology in which the bag body of an airbag is sewn together and a coating material is applied to the sewn area to prevent inflation gas from leaking from the sewn area, resulting in insufficient inflation or slow inflation.

[0005] Special table number 2016-533293

[0006] Patent Document 1 describes applying a coating material to a seam by either applying it to only one side and letting it reach the other side along the stitching hole, or by applying it to both sides to cover the seam. Since the viscosity of the coating agent when applying it to both sides is not specifically disclosed, it is believed that the same coating agent is used for the first and second sides. If a low-viscosity coating agent (the binder in this application) is used, problems may arise in that the coating material penetrates the other side when applied to the first side and adheres to the base supporting the bag, or the coating material that has adhered to the base may re-adhere to unexpected parts of the bag. Furthermore, whether the coating agent is applied to both sides or one side, depending on the viscosity of the coating agent, if the yarn is twisted, the coating agent may not penetrate between the fibers that make up the twisted yarn. As a result, the twist of the yarn tightens due to the large tension applied to the yarn during airbag inflation, creating a gap between the suture thread and the cross section of the base fabric where the suture thread passes through the stitching hole, potentially resulting in leakage of airbag inflation gas.

[0007] Therefore, the present invention is configured such that at least a portion of the fibers of the suture are bound with a binder, preventing the twist of the twisted thread from tightening even when the airbag is inflated. This is because the presence of a binder layer between the fibers prevents the fibers from shifting and narrowing the fiber spacing. This configuration prevents gaps from forming between the suture and the suture insertion cross section of the base fabric at the sewn hole. To prevent the binder from adhering to the base on the opposite side of the applied surface when applied to the sewn hole, the exposure rate of the suture from the binder in areas of the base fabric other than the sewn hole and the rate at which the suture is covered with the binder are specified. Furthermore, the area ratio of the suture cross section (the ratio of the binder cross-sectional area to the cross-sectional area of ​​the thread) is specified to determine the ratio of the binder between the fibers constituting the suture. Furthermore, by optimizing the viscosity range of the binder (corresponding to the "coating agent" in Patent Document 1) and applying it from both sides, the binder applied first is one with a higher viscosity than the binder applied to the opposite side, thereby preventing the low-viscosity binder from adhering to the support base when the binder is applied from the opposite side through the bag body and the seams of the bag body during the application operation.

[0008] Even in the case of one-sided application, by specifying the viscosity, the seam can be sealed efficiently, the flow of the binder onto the surface of the base fabric opposite the applied surface can be adjusted, and a predetermined rate of binder can be dispersed between the fibers that make up the suture thread. In the case of double-sided application, by using a binder with a lower viscosity than the binder initially applied as the binder applied to the other side, the binder can more easily penetrate between the fibers that make up the twisted yarn and be integrated with the binder initially applied, allowing for efficient sealing of the seam. Furthermore, the object is to provide a method for manufacturing an airbag body that can bind at least some of the fibers that make up the suture thread so that gaps are less likely to form between the suture thread and the cross section of the base fabric where the suture thread is inserted at the sewn hole as a result of the tightening of the ``twist'' of the fibers of the twisted suture thread.

[0009] In order to solve the above problems, the present invention provides the following: As a first invention, an airbag comprising a sheet-like first base fabric, a sheet-like second base fabric, and a sewing thread that sews together the first and second base fabrics, the sewing thread being made by twisting a plurality of fibers together to form a gas injection space with the first and second base fabrics, wherein the fibers of at least some of the sewing threads are bound together with a binder so that voids are less likely to form between the sewing thread and the base fabrics at the sewn hole as a result of the twist being tightened by the tension generated in the sewing thread.

[0010] As a second invention, based on the first invention, there is provided an airbag described above, in which at least a part of the suture thread is exposed from the binder in a portion other than the sewn hole on at least one or more of the first base fabric and the second base fabric.

[0011] As a third invention, based on either the first or second invention, there is provided an airbag in which, in a region of substantially the same width as the thickness of the suture thread along the sewing direction on the surface of one of the base fabrics on which a binder has been applied to the seam of the base fabric, the two-dimensional area ratio of the suture thread at least partially exposed from the binder is greater than 0% and not more than 30%.

[0012] As a fourth invention, based on any one of the first to third inventions, there is provided an airbag in which the two-dimensional area ratio of the portion covered with the binder (including both the suture thread and the base fabric) is 5% or more in an area of ​​approximately the same width as the suture thread (which may also include the suture thread from the opposite base fabric) along the sewing direction on the surface of one of the base fabrics on which the binder has not been applied to the seam portion of the base fabric.

[0013] As a fifth invention, there is provided an airbag based on any one of the first to fourth inventions, in which the suture thread on the base fabric side to which the binder is applied has a cross-sectional area of ​​the binder of 10% to 25% of the cross-sectional area of ​​the suture thread (55% to 100% of the cross-sectional area of ​​the portion of the suture thread other than the fiber).

[0014] As a sixth invention, there is provided an airbag based on any one of the first to fifth inventions, in which the suture thread on the side of the base fabric to which the binder has not been applied has a cross-sectional area of ​​the binder of 5% to 25% of the cross-sectional area of ​​the suture thread (35% to 100% of the cross-sectional area of ​​the portion of the suture thread other than the fiber).

[0015] As a seventh invention, based on the first invention, there is provided an airbag in which, when at least a portion of the seams of the first base fabric and / or the second base fabric are made of woven fabric, the fibers making up the woven fabric near the seams of the first base fabric and / or the second base fabric are bound with a binder so that the fibers making up the woven fabric at the seams of the first base fabric and / or the second base fabric are less likely to come undone.

[0016] As an eighth invention, there is provided an airbag based on either the first or seventh invention, in which the fibers near the seams of the first base fabric and / or the second base fabric are bound with a binder so as to make the fibers that make up the woven fabric less likely to unravel.

[0017] As a ninth invention, there is provided a method for manufacturing an airbag according to any one of the first, seventh, or eighth inventions, which includes a first base fabric penetration step of penetrating a first binder from the seam of the first base fabric into the sewing thread, and a second base fabric penetration step of penetrating a second binder from the seam of the second base fabric into the sewing thread.

[0018] As a tenth aspect of the present invention, there is provided a method for producing an airbag based on the ninth aspect of the present invention, in which the first binder and the second binder have different viscosities.

[0019] As an eleventh invention, there is provided a method for manufacturing an airbag based on either the ninth or tenth invention, in which a first binder and a second binder are applied on a flat table, and the binder applied first of the two binders has a higher viscosity than the binder applied later.

[0020] As a twelfth invention, there is provided a method for manufacturing an airbag based on any one of the ninth to eleventh inventions, in which a relatively high viscosity binder that is applied first is applied to the upper thread side that is bound to the lower thread on the surface of the base fabric by passing a single stitch of sewing thread through the base fabric.

[0021] As a thirteenth invention, there is provided a method for manufacturing an airbag according to the first invention, comprising: a binder penetration step of applying a binder to a stitched portion on the surface of either a first base fabric or a second base fabric, and allowing the binder to penetrate through stitched holes in the stitched portion to intersect with the fibers that make up the stitching thread within the stitched holes; and an opposite base fabric suture fiber binder penetration step of allowing the binder to penetrate through the stitched holes to at least some of the intersect with the fibers that make up the stitching thread exposed between the stitched holes on the surface of the base fabric opposite to the base fabric to which the binder has been applied (a different suture thread from the suture exposed between the stitched holes on the surface of the applied side base fabric).

[0022] As a fourteenth invention, there is provided a method for manufacturing an airbag based on the thirteenth invention, further comprising an inter-fabric bonding step in which a portion of the binder that has permeated through the sewn holes accumulates between the first and second base fabrics, bonding the first and second base fabrics together.

[0023] As a fifteenth aspect, there is provided a method for manufacturing an airbag based on any one of the ninth to twelfth aspects, wherein the difference in viscosity when the binder is applied is measured in Pascal seconds, and the viscosity range of the high-viscosity binder and the low-viscosity binder is 3.0 mPa s to 90 Pa s.

[0024] As a sixteenth invention, there is provided a method for manufacturing an airbag based on any one of the thirteenth and fourteenth inventions, wherein the difference in viscosity when the binder is applied is measured in Pascal seconds, and the viscosity range of the high-viscosity binder and the low-viscosity binder is 3.0 mPa s to 90 Pa s.

[0025] With the above-described configuration, the present invention is configured such that at least a portion of the fibers of the suture are bound together with a binder, preventing the twist of the twisted thread from tightening even when the airbag is inflated. This is because the binder layer between the fibers and the fibers are bonded together by the binder prevent the fibers from shifting and narrowing. This configuration also reduces the likelihood of gaps forming between the suture and the cross-section of the base fabric where the suture is inserted at the sewn hole. To prevent the binder from adhering to the base on the opposite side of the applied surface when applied to the sewn hole, the exposure rate of the suture from the binder and the coverage rate of the suture are specified in areas of the base fabric other than the sewn hole. Furthermore, the area ratio of the suture cross section (the ratio of the binder cross-sectional area to the cross-sectional area of ​​the thread) is specified for the binder ratio between the fibers constituting the suture. Furthermore, by optimizing the viscosity range of the binder (corresponding to the "coating agent" in Patent Document 1), when coating from both sides, a binder with a higher viscosity than the binder to be coated on the opposite side is used as the binder to be coated first, thereby preventing the low-viscosity binder from adhering to the support base when the binder is applied from the opposite side through the bag body and the seams of the bag body during the coating operation.

[0026] Even in the case of one-sided application, by specifying the viscosity, the seam can be sealed efficiently, the flow of the binder onto the surface of the base fabric opposite to the applied surface can be adjusted, and a predetermined rate of binder can be dispersed between the fibers that make up the suture thread. In the case of double-sided application, by using a binder with a lower viscosity than the binder initially applied as the binder applied to the other side, the binder can more easily penetrate between the fibers that make up the twisted yarn and become integrated with the binder initially applied, allowing for efficient sealing of the seam. Furthermore, as a result of the tightening of the "twist" of the fibers of the twisted suture thread, it is possible to provide a method for manufacturing an airbag body that can bind at least some of the fibers that make up the suture thread so that gaps are less likely to form between the suture thread and the cross section of the base fabric where the suture thread passes through at the sewn hole.

[0027] Schematic plan view of a seam of an airbag according to embodiment 1 of the present invention. Schematic cross-section AA' of a seam of an airbag according to embodiment 1 of the present invention. Schematic plan view of a seam of embodiment 1 of the present invention when the airbag is inflated. Schematic cross-section of a seam of embodiment 1 of the present invention when the airbag is inflated. Schematic plan view of a seam of an airbag according to embodiment 2 of the present invention. Schematic cross-section 1 of a seam of an airbag according to embodiment 2 of the present invention. Schematic cross-section 2 of a seam of an airbag according to embodiment 2 of the present invention. Example of a flowchart of a manufacturing method according to embodiment 4 of the present invention. Airbag according to embodiment 5 of the present invention. Schematic plan view showing an example of the end of the first base fabric penetration step of the airbag of embodiment 5 of the present invention; Schematic cross-sectional view showing an example of the end of the first base fabric penetration step of the airbag of embodiment 5 of the present invention; Schematic cross-sectional view showing an example of the end of the second base fabric penetration step of the airbag of embodiment 5 of the present invention; Schematic plan view showing an example of the start of the second base fabric penetration step of the airbag of embodiment 6 of the present invention; Schematic cross-sectional view showing an example of the start of the second base fabric penetration step of the airbag of embodiment 6 of the present invention; Schematic cross-sectional view of the airbag according to the seventh embodiment of the present invention. Schematic cross-sectional view of the airbag according to the seventh embodiment of the present invention after the binder has penetrated. Schematic view of an example of the structure of the suture thread of the present invention. Schematic view of an example of the cross-sectional structure of the suture thread of the present invention. Graph showing the time change in pressure inside the airbag when inflated. Graph showing the relationship between the viscosity of the binder when applied and the gas retention inside the airbag. Schematic view showing the hardening of the binder according to the present invention. Schematic view showing an example of applying the binder to the suture thread of the present invention in advance. Schematic view showing an example of the dimensions of the binder according to the present invention after hardening. FIG. 12 is an explanatory diagram of a type of passenger vehicle airbag; FIG. 13 is a schematic plan view of a seam of a second embodiment of the present invention; FIG. 14 is a schematic longitudinal cross-sectional view of a seam of a second embodiment of the present invention; FIG. 15 is an SEM photograph of a surface near the seam on a base fabric surface where a binder has been applied to the seam; FIG. 16 is a SEM photograph of a surface near the seam on a side of the base fabric where no binder has been applied to the seam; FIG. 17 is a cross-sectional view of a sewn hole where a binder has been applied to one side from the base fabric side on the SEM photograph;

[0028] Hereinafter, embodiments of the present invention will be described. However, the present invention should not be limited to these embodiments and can be implemented in various forms without departing from the spirit of the present invention. Reference numerals in the description of the configuration of the present invention and in the diagrams illustrating the configuration in this specification are represented by four-digit numbers, with the first two digits representing the drawing number and the last two digits representing numbers uniquely assigned to each part. The reference numerals indicating each operational step in the diagram showing the process flow in Figure 7 are assigned in the order of processing, regardless of the above-mentioned method of assigning reference numerals.

[0029] <Airbag: Structure> An airbag is composed of an inflator (mostly an inflator that burns gunpowder) that generates gas to inflate the bag, an acceleration sensor for detecting a collision, a control circuit, the bag, and a rotating connector (driver's seat only). In this specification, the bag of an airbag will be referred to as an airbag in the narrow sense.

[0030] <Airbags: Types> Airbags are used in a variety of vehicles, but the most familiar airbags are those used in passenger cars. Figure 24 shows an example of an airbag installed in the interior of an automobile. Various airbags are installed in the interior of an automobile, including a driver's airbag (2420) stored in the steering wheel of the driver's seat to protect the driver's head and chest in a frontal collision; a passenger airbag (2421) stored in the dashboard on the passenger side to protect the passenger's head and chest in a frontal collision; a side curtain airbag (2422) attached to the top of the door opening and deployed to cover the window to protect the head and neck of the driver, passenger, or rear seat passengers in a side collision or rollover; a side airbag (2423) stored on the left and right sides of the seat to protect the chest and abdomen of the driver, passenger, or rear seat passengers in a side collision; and a knee airbag (2424) to protect the passenger's legs and reduce impact to the knees. A center airbag (2425) is placed between the driver's seat and the passenger seat. This airbag is designed to prevent the driver and passenger in the passenger seat from colliding with each other and to prevent the head from coming into contact with interior materials such as doors on the opposite side of the collision (non-collision side).

[0031] Among these, the driver's airbag (2420) and passenger's airbag (2421) have a large volume when inflated, and because passengers are likely to be hit by them in the event of an accident, if they remain inflated, the passengers will collide with the airbag and sustain damage. Therefore, the front-seat airbags must inflate, absorb the forward inertia of the passenger, and then immediately release the inflation gas and deflate, thus providing a gas release valve. Among the other airbags, the side curtain airbag (2423) inflates between the passenger and the window during a side collision. To prevent the passenger from being injured or thrown out of the vehicle due to contact with the window, broken window glass, or the exterior of the vehicle when the passenger sways sideways, it must remain inflated for several seconds (e.g., six seconds or more) longer than the driver's and passenger's airbags. The center airbag also deploys to protect passengers in a side collision and must remain inflated, though not for as long as the side curtain airbags. 24, a pedestrian protection airbag deployed on the hood is also an airbag that should remain inflated for a certain period of time without actively releasing the gas. Therefore, it is preferable that the inflation gas of these airbags is not easily released, and these airbags are suitable for applying the airbag or manufacturing method thereof of the present invention.

[0032] <Embodiment 1> <Outline of embodiment 1> Mainly claim 1

[0033] The airbag of this embodiment comprises a sheet-shaped first base fabric, a sheet-shaped second base fabric, and a sewing thread that sews the two together, and is configured such that at least some of the fibers of the sewing thread are bound together with a binder.

[0034] <Configuration of Embodiment 1> The configuration of this embodiment 1 will be described using Figures 1 and 2. Figure 1 is a schematic plan view of one stitched portion of an airbag (0100) observed from the normal direction of the base fabric surface. The stitching (0104) constituting the stitching portion and the binder (0105) covering the top and both side surfaces of the stitching (0104) are shown. The stitching (0104) appears discontinuous because the stitching (0104) on the observation side is pulled by the stitching (0104) on the back side, forming a stitched hole that is not visible from the surface of the base fabric on the observation side. Furthermore, the portion of the stitching (0104) indicated by a thick solid line in Figure 1 does not indicate that the stitching (0104) is directly exposed on the observation surface of the airbag (0100), but rather indicates the portion where the binder (0205) covers the top surface of the stitching (0204) as shown in Figure 2. If the binder is transparent, the suture can be visually observed at this portion.

[0035] <Embodiment 1: Outline of the Structure of the Seam: Plan View> Figure 1 is a schematic plan view of a seam where the base fabric of an airbag of Embodiment 1 is sewn together. The upper horizontal solid line in the figure indicates the end face of the airbag, and the left, right, and bottom wavy lines indicate that the portion continuing beyond that point has been omitted. Figures 3, 5, 8, 10, 12, 14, and 25, which will be used in the description of other embodiments described later, use a similar representation to Figure 1. Note that in the figures in this specification, the seam at the end of the airbag is shown as being located at the end, but is not limited to the end, and seam located inside the base fabric or in a portion between another seam and the end may also be covered by the present invention.

[0036] <Embodiment 1: Outline of the Structure of the Stitched Portion: Longitudinal Cross-Section> Figure 2 is a schematic longitudinal cross-sectional view of the stitched hole, near the stitched hole, along the stitching thread (0104) of the stitched portion indicated by A-A' in Figure 1. The area indicated by B in Figure 1 is the area where the stitching thread on the observation side of the airbag in Figure 1 is pulled by the stitching thread on the back side and becomes invisible, and the binder covers the stitching hole. In the following description, including Figure 1, only one stitching is illustrated, but the stitching of the airbag can also be configured with multiple stitching threads running parallel to one another. Furthermore, Figure 2 shows the binder (0205) completely covering the stitching thread (0204) on the surface of the base fabric, but at least a portion of the stitching thread may be exposed from the binder. Furthermore, the thickness of the binder (0205) on the surface of the upper first base fabric (0201) or the lower second base fabric (0202) shown in Figure 2 may be different.

[0037] Figure 2 is a schematic diagram of a longitudinal cross section along a seam of an airbag. The seam of the airbag is made up of a first base fabric (0201), a second base fabric (0202), fibers (0203) constituting the seam, a seam thread (0204) formed by bundling a plurality of fibers (0203), and a binder (0205). In order to distinguish between the upper and lower threads when sewing with a sewing machine, the seams are shown in white and light gray in Figure 2. In practice, the same color seam threads may be used, or the colors may be intentionally changed (the same applies below).

[0038] <Embodiment 1: First base fabric (0201), second base fabric (0202)> The "first base fabric" (0201) and the "second base fabric" (0202) are in the form of sheets, and the first base fabric (0201) and the second base fabric (0202) are sewn together to form a gas injection space, thereby forming a bag body.

[0039] The first base fabric "first base fabric" and the second base fabric "second base fabric" are each configured in a sheet-like shape. The base fabrics may be woven fabrics made by weaving threads, knitted fabrics, nonwoven fabrics, or sheets made by stretching synthetic resins into thin films, and can be selected appropriately depending on the desired performance.

[0040] <Embodiment 1: First Base Fabric / Second Base Fabric: Base Fabric Material> The airbag bag, formed by sewing together a first base fabric and a second base fabric, is inflated by gas generated by the combustion of explosives by an inflator. Therefore, the first and second base fabrics constituting the airbag must be made of a material that can withstand the sudden inflation caused by the instantaneous high-temperature and high-pressure gas, be strong enough to withstand the impact of a occupant coming into contact with them, and be as soft as possible, considering the need to support the occupant. If both base fabrics are woven, they may be made of known airbag fabrics, such as nylon, polyethylene terephthalate, or polyester. If the base fabric is woven, it may be coated with a silicone resin or urethane resin (usually applied to one side of each base fabric), or uncoated. The coated surface of the coated fabric may be configured to face either the outside or the inside of the bag. The combination of the coating resin (e.g., silicone resin or urethane resin) and the binder (described below) can be selected appropriately based on the adhesive strength between them.

[0041] The presence or absence of a coating on the fabric and the thread density of the fabric affect how the inflation gas escapes from the inflated airbag, so they can be selected appropriately depending on the type of airbag to be used and its required specifications. For driver's and passenger's seat airbags, which have large bags and large amounts of inflation gas and have vent holes for venting the gas after inflation, uncoated fabrics are used. For side curtain airbags, which have thin airbags without vent holes and must retain a small amount of gas for a relatively long time, coated fabrics are used. The first and second base fabrics may be coated or uncoated, or the fabric density may be different, or the fabric materials may be different. Selection can be made appropriately depending on the design of the airbag's inflation and deflation.

[0042] <Embodiment 1: First base fabric / second base fabric: base fabrics constituting the airbag> In the description herein, the first base fabric and the second base fabric are illustrated as being composed of one piece each, but each may be composed of multiple pieces (e.g., a long, narrow tape-like fabric is placed near the seam and then sewn together to reinforce it; approximately identical pieces of fabric are superimposed to form one side of the base fabric, etc.). Alternatively, one may be a single piece and the other may be composed of multiple pieces. The first base fabric or the second base fabric may each be a single, sheet-like base fabric, or may be formed by joining multiple sheet-like base fabrics together. When joined together, sheet-like base fabrics of different materials may be joined together instead of sheet-like base fabrics made of the same material. Furthermore, the airbag bag body may be configured to form a three-dimensional shape by sewing together base fabrics of different shapes, rather than by overlapping and sewing together first and second base fabrics of approximately the same shape. The airbag may be cylindrical in shape, consisting of a top, bottom, and sides, or may be shaped like a mushroom cap (hamburger bun) made by three-dimensionally sewing together fabrics of different shapes. The seam basically sews together two types of fabric, a first sheet-like base fabric and a second sheet-like base fabric, but the scope of the present invention also includes cases where more than two types of fabric sheets are sewn together due to the structural design of the airbag.

[0043] <Embodiment 1: Suture thread (0204)> The suture thread (0204) shown in Fig. 2 is formed by twisting and bundling a plurality of fibers (0203), and is used to sew together a first base fabric and a second base fabric. Furthermore, at least some of the fibers of the suture thread are bound together with a binder, which will be described later, so that the tension generated in the suture thread tightens the twist and prevents gaps from forming between the suture thread and the base fabrics at the sewn hole.

[0044] <Embodiment 1 Suture (0204): Structure> Figure 17 is a schematic diagram showing an example of the structure of a suture. The suture shown in the schematic diagram of Figure 17 is shown with the twist gradually loosening toward the top to make the structure easier to understand. The suture in the example of Figure 17 is a large-diameter twisted suture (1704) made by twisting three small-diameter twisted yarns, each of which is formed by twisting a monofilament fiber (1703) in an S twist in one direction, into a Z twist. S twist and Z twist are distinctions based on the twist direction of the yarn. When the twisted yarn is viewed from the side, if the fibers constituting the small-diameter twisted yarn (the small-diameter twisted yarn relative to the large-diameter twisted yarn) are twisted upward to the left, it is called an S twist, and if they are twisted upward to the right, it is called a Z twist. However, this twisting process is just one example, and any twisted process can be considered a suture as defined in the present invention. In the example shown in Figure 17, the binder (1705) shown in gray permeates the suture thread (1704) in various places, binding at least some of the monofilament fibers (1703) together with the binder, making them less likely to slip. In addition to the monofilament fibers (1703), the binder (1705) also binds at least some of the three small diameter twisted yarns formed by twisting monofilaments together, making them less likely to slip.

[0045] Figure 18 is a schematic diagram showing a cross section of the dd' portion in Figure 17. The small circles represent monofilament fibers (1803). The small diameter twisted yarns are divided into three groups of multiple fibers (42 fibers each) surrounded by circular dotted lines, and the circular dotted lines surrounding the three small diameter twisted yarns represent the large diameter twisted yarn suture (1804). The fibers (1803) and the small diameter twisted yarns are at least partially bound together by a binder (1805). Note that Figure 2 does not show the binder (0205) penetrating between at least some of the fibers (0203) of the suture (0204). Unless otherwise specified, this is not shown in the figures in this specification, but it is assumed that the binder penetrates between at least some of the fibers that make up the suture, binding them together and preventing slippage.

[0046] <Embodiment 1: Effect of Binder on Suture Thread (0204)> The binder (1705) between the fibers (1703) applies tension to the suture thread (1704) during sewing, as well as tension during airbag inflation, which tends to tighten the twist. However, the binder secures the fibers (1703) and / or small-diameter twisted yarns together, preventing slippage. This prevents the distance between adjacent fibers (1703) or adjacent small-diameter twisted yarns from shrinking, preventing the diameter of the suture thread from becoming thinner. This will be explained using the table in Figure 21. In Figure 21, the left column shows suture thread without binder penetration, and the right column shows suture thread in which binder has penetrated at least some of the fibers that make up the suture thread. The top row shows the state of the suture thread before tension is applied during airbag inflation, and the bottom row shows the state after tension is applied during airbag inflation. The left column of each column is a simplified outline of the outer shape of the suture thread, intended to indicate the change in diameter. The right side of each column shows a cross-sectional view of a portion of the fibers that make up the suture thread. The distance between the fibers that make up the suture thread and the diameter of the suture thread before tension is applied when the airbag is inflated are approximately the same whether or not the binder is permeated. The cross section of the twisted fibers is elliptical because the binder crosses the fibers diagonally. In suture threads that have been permeated with the binder, at least some of the fibers are bonded together by the binder.

[0047] When tension is applied during airbag inflation, the suture thread in the lower left column, which is not permeated with binder, experiences tension, causing the fibers to shift, narrowing the gaps between the fibers. The angle of the fibers crossing the cross section may shift toward a vertical direction, causing the shape to change from an ellipse to a circle. These effects reduce the diameter of the suture thread. When tension during airbag inflation is applied to the suture thread in the lower right column, which is at least partially permeated with binder, the fibers bound by the binder are less likely to shift, and the distance between the fibers does not change, so the cross section of the fibers crossing the cross section remains roughly the same ellipse as before tension was applied. These effects ensure that the thickness of the suture thread remains roughly the same as before tension was applied. Therefore, no gaps are created between the suture thread and the base fabric at the sewn holes, preventing leakage of inflation gas when the airbag is inflated. Without the binder, as shown in the lower left column of Figure 21 (no binder, suture thread after tension application) the diameter of the suture thread (1704) would narrow when tension is applied during airbag inflation, creating a gap between the suture thread and the cross section of the base fabric where the suture thread passes through the sewn hole, allowing inflation gas to leak when the airbag inflates. By allowing a binder to permeate between at least some of the fibers of the suture thread, it is possible to prevent such gas leakage when the airbag inflates.

[0048] <Embodiment 1 Suture thread (0204): Material> The fiber (0203) can be a fiber that constitutes a known thread for sewing airbags, such as polyamide fiber, polyester fiber, biopolyester fiber, etc. In particular, biopolyester fiber is expected to be increasingly adopted in response to the growing consumer awareness of environmental issues and interest in the SDGs in recent years.

[0049] <Embodiment 1 Suture (0204): Thickness, Fineness> The fiber diameter can be selected appropriately depending on the specifications required for the thread constituting the suture portion. If the fiber diameter is large, the number of fibers constituting the suture will be small, resulting in a thread with high rigidity and difficulty in sewing. Examples of suture specifications include a single-fiber fineness of 10 dtex or less and a total fineness of 200 to 3100 dtex, more preferably 900 to 1800 dtex (130 to 210 fibers), and these can be selected appropriately. Rather than constructing a suture from a single fiber, such as nylon fishing line, a bundle of multiple thin fibers is preferable because it is more flexible, easier to handle during sewing, and less likely to break if damaged. If a single fiber is damaged, the damage will widen due to tension or other factors, causing the thread to break. However, if the suture is constructed from multiple fibers, it is supported by the undamaged fibers and less likely to break.

[0050] An example of a suture thread is one in which approximately 20 to 50 nylon monofilaments with a diameter of 0.02 to 0.04 mm are twisted together to form three small-diameter twisted yarns with a diameter of approximately 0.1 to 0.3 mm, which are then twisted together to form a single large-diameter twisted yarn (diameter approximately 0.5 mm), i.e., a suture thread (approximately 1000 dtex). However, the number of small-diameter twisted yarns is not limited to three, and multiple small-diameter twisted yarns are preferred. The number of small-diameter twisted yarns is preferably approximately 2 to 7. Alternatively, a single yarn may be formed by twisting together 130 to 210 monofilaments without creating a small-diameter twisted yarn. However, in this case, a binder with a lower viscosity is required to penetrate to the center of the suture thread. In this case, a binder with a viscosity of approximately 0.05 Pa·s to 2.0 Pa·s is suitable.

[0051] <Embodiment 1: Sewing Thread (0204): Seam> When sewing using a sewing machine, two types of thread are used: an upper thread and a lower thread. However, different threads of different materials and strengths may be used depending on the purpose. When the seam is asymmetrical in cross section, as shown in FIG. 15 , it is preferable to make the shear strength of the thread on the side that receives tension during the airbag inflation process higher than that of the other seam. In the case of the stitching style shown in FIG. 15 , the seam (1504a) on the side that is pulled into the seam receives higher tension during the airbag inflation process, so it is preferable to make the shear strength of that seam (1504a) higher than that of the other seam (1504b). To distinguish between the first and second backing fabrics and between the upper and lower threads, it is preferable to use different colors for the upper and lower threads, such as blue and red. While only straight stitching is shown in the figures in this specification, other stitching methods may also be used.

[0052] <Embodiment 1: Sewing thread (0204): Seams: Multiple rows> Although the present specification illustrates and describes a single row of stitches, multiple rows of stitches may be used (the same applies to other embodiments). When sewing using sewing thread, a single row of stitches may be used, but multiple rows of stitches are preferable because they are more likely to withstand the force applied when the airbag inflates. When two rows of stitches are used, the force applied to the seams when the airbag inflates is mostly received by the seams on the inside of the airbag, reducing the force applied to the seams on the outside and reducing leakage of inflation gas. The number of stitches may be three or more rows, more than two. When sewing a base fabric with more rows of stitches than the number of needles of a sewing machine, multiple stitches may be used. A sewing machine equipped with multiple needles corresponding to the number of rows of stitches may be used to sew the base fabric at one time. Increasing the number of rows increases the manufacturing cost, the weight of the airbag itself (the seam allowance, which is the area of ​​the seam and the adhesive applied to the seam), and other side effects such as difficulty in folding. The number of seams that minimizes side effects while maintaining strength is three or less, with two rows being preferable.

[0053] When there are multiple rows of stitching, the distance between the rows of stitching (the distance between the center lines of the stitching) is 1 mm or more and 10 mm or less, preferably 7 mm or less, and more preferably 5 mm or less.

[0054] <Embodiment 1 Suture (0204): Penetration of Binder> Before being used to sew a base fabric, at least some of the fibers of the suture may be bound together with a binder, as described below. As shown in Figure 22, during the manufacture of the suture, before winding it onto a reel (2210) or the like, the binder (2205) is intermittently applied to the suture (2204) from a discharge nozzle (2211) in a length equivalent to 1 mm, followed by a 0.5 mm gap without application, and then repeatedly applied to the suture to allow the binder to penetrate between the fibers. The suture is then heated with an infrared lamp heater (2212) or the like to provide suitable hardening and drying conditions for the binder, and the suture is wound up, thereby producing a suture in which the binder has already penetrated between at least some of the fibers. Alternatively, when sewing a base fabric using a sewing machine or the like, the binder may be permeated into the suture just before it is unwound and passed through the base fabric. However, since sewing the first and second base fabrics together applies sewing tension (tension generated between the suture threads and tension based on the pressure applied by the base fabrics) to the free suture thread, it is preferable to bind them with a binder after the sewing tension has been applied. Since it takes a certain amount of time for these tensions to become constant after sewing, it is preferable to apply the binder after the tensions have become constant. The time required for the tensions to become constant is at least one second and approximately five minutes. This time length varies depending on the type of suture thread and the material of the base fabric.

[0055] <Embodiment 1: Binder (0205)> The binder (0205) binds at least some of the fibers (0203) of the suture thread (0204) together so that the tension generated in the suture thread (0204) tightens the twist, thereby preventing gaps from forming between the suture thread and the base fabric at the sewn hole.

[0056] <Embodiment 1: Binder: Material and Properties> The material of the binder (0205) can be selected from resins such as silicone resin, polyvinyl chloride resin, urethane resin, polyurethane resin, or other elastomers. When the airbag is stored in a predetermined position inside the vehicle, such as the steering wheel, seat, pillar, or upper part of the side window, the stitched portion to which the binder is applied is also folded, so the binder must be a material that remains flexible even after drying. The hardness after curing, measured using a durometer type E or A specified in JIS K6253-3, is preferably between 0 and 30. A more preferred range is 5 to 20, and preferably between 5 and 15.

[0057] If the first and / or second base fabrics are coated fabrics, a binder made of the same material as the coating material on the surface of the base fabrics is desirable because it is expected to increase adhesive strength. For example, in a base fabric coated with silicone rubber, the silicone rubber itself can be made flame-retardant by blending a known flame retardant into the silicone rubber. Therefore, when using a base fabric configured in this way, it is preferable to use the same silicone rubber-based resin as the binder. Furthermore, if the coating agent for the base fabric is a urethane resin, it is preferable to use a urethane resin-based binder as well, and if a polyvinyl chloride resin is used as the coating agent, it is preferable to use a polyvinyl chloride resin as the binder.

[0058] In order for the binder to penetrate the fibers of the suture and bond the fibers together, it must have good adhesion to the fibers. Nylon fibers are more difficult to bond with adhesives than polyester fibers. When using sutures made of nylon fibers, a binder that can bond nylon must be selected, such as a silicone resin or urethane resin. The binder must be selected based on the type of material that makes up the suture and / or base fabric (e.g., fiber, base fabric coating material, film base fabric material, etc.).

[0059] <Embodiment 1: Application of Binder after Sewing> Examples of methods for penetrating the binder (0205) between the fibers of the suture thread include applying the binder to the seam using a dispenser or syringe, silkscreen printing, inkjet printing, or brush application after sewing the first base fabric (0201) and the second base fabric (0202) together with the suture thread (0204). Examples of methods for applying the binder include applying it to the seam from the first base fabric side, drying it, and then applying it to the seam from the opposite second base fabric side. Alternatively, there is a one-sided application method in which the binder is applied to the seam only from the first base fabric side. The binder penetrates between the fibers of the suture thread exposed on the surface of the base fabric. Furthermore, in the seam, the binder penetrates through the holes in the seam, along the suture thread (0204), and between the fibers (0203) that make up the suture thread (0204). As a result, by binding at least a portion of the fibers (0203) constituting the suture thread (0204) with the binder (0205), the fibers (0203) are less likely to shift or separate. As the binder penetrates between the fibers in this way, the binder (0205) also fills the gaps between the base fabric and the suture thread (0204) at the sewn portion. As explained above in the effect of the binder in the explanation of the suture thread, even when tension is applied when the airbag is inflated, the diameter of the suture thread (0204) does not become narrower, and it is possible to prevent gaps from forming between the suture thread and the base fabric at the sewn hole.

[0060] In the present embodiment, Figs. 1 and 2 show an example in which the binder (0205) is applied to the sutured portion by the method described above, but as described in the explanation of the suture thread, it is also possible to use a suture thread (0204) that has been previously impregnated with the binder (0205) for suturing, and not apply the binder to the sutured portion after suturing.

[0061] <Embodiment 1: Binder: Seam during Airbag Inflation> The seam during airbag inflation will be described using Figures 3 and 4 . Figure 4 is a cross-sectional view of the seam of the airbag, and Figure 3 is a plan view of the seam of the airbag showing the C-C' portion of the cross-sectional view in Figure 4 . As shown in Figure 4 , the airbag is sandwiched between a first base fabric (0401) and a second base fabric (0402), and the space enclosed by the seam of the seam (0404) is inflated with gas. At the seam, the first base fabric (0401) and the second base fabric (0402) inside the seam tend to move away from each other as indicated by the arrows in Figure 4 , creating tension that stretches the seam (0404) sewing the two base fabrics together. When a force that stretches the seam is applied, the twist of the thread tends to tighten, and the diameter of the thread tends to shrink. If the stitching is made by simply sewing the base fabric with a stitching thread that does not have at least some of the fibers bound together with a binder, the stitching hole that was almost completely filled with the stitching thread before inflation will be stretched and tightened by the tension when the airbag inflates, causing the diameter of the stitching thread to shrink, creating a gap between the base fabric and the stitching thread at the stitching hole, allowing the inflation gas to leak.

[0062] In the present invention, as shown in Figure 4, at least some of the fibers of the suture thread (0404) in the stitched hole portion of the stitched portion are bound together by the binder (0405) permeating between them. As shown in Figure 17, the binder (1705) permeates and binds the fibers (1703) that make up the suture thread (1704) or between the small-diameter twisted yarns made up of multiple twisted fibers. This fixes the fibers, preventing the distance between the fibers or the small-diameter twisted yarns from shrinking, preventing the twist from tightening and narrowing the diameter of the suture thread. This reduces the likelihood of voids forming between the suture thread and the cross section of the base fabric where the suture thread is inserted in the stitched hole. Because voids are less likely to form in the stitched hole, leakage of inflation gas from the stitched hole is reduced. The suture thread is also less likely to stretch. Furthermore, by covering the entire stitched portion with the binder (0405) from both surfaces of the base fabric, as in the examples of Figures 3 and 4, the stitched portion is further strengthened, reducing gas leakage from the stitched hole.

[0063] <Embodiment 1: Binder: Application Area> As shown in Figure 23, when applying the binder (2305) along the seam, the width (d1), the distance (d2) from the seam to the inner application edge, the distance (d3) from the seam to the application edge on the outer edge of the base fabric, and the distance (d4) between the application edge on the edge of the base fabric and the edge of the base fabric are preferably as follows. Note that the following applies to a single line of seams. Since the binder is generally applied to the seam along the entire seam, it tends to spread almost symmetrically around the seam. If the base fabric is wavy or uneven due to the stitching, this may result in unevenness. Therefore, if d1 is narrow, d2 and d3 tend to be small, and if d1 is large, d2 and d3 tend to be large. d1 is in the range of 3 to 30 mm, more preferably 5 to 20 mm, and most preferably 7 to 15 mm. d2 is in the range of 2 to 15 mm, more preferably 3 to 10 mm, and most preferably 4 to 8 mm. d3 is 1 to 15 mm, more preferably 2 to 10 mm, and most preferably 3 to 7 mm. d4 is 0 to 14 mm, preferably 5 to 13 mm, and even more preferably 8 to 12 mm. The seam closest to the edge of the base fabric is more preferably positioned 5 to 20 mm, preferably 10 to 15 mm, from the edge of the base fabric.

[0064] When there are multiple rows of seams, the binder may be applied to each seam (there may be gaps between the seams), or the binder may be applied to cover all of the rows of seams. When there are multiple rows of seams, d3 and d4 in Figure 23 are the distances to the seams closest to the edge of the base fabric, d2 is the distance to the seam farthest from the edge of the base fabric, and d1 is calculated as d1 = (the sum of the spacing between the rows of seams) + d2 + d3.

[0065] These dimensions may be taken at the maximum or minimum position of the binder end face, or at the average position of the wavy end face. If the width of the application area is too narrow, the stitching thread will not be sufficiently fixed to the base fabric, and when the airbag inflates, the gap between the stitching thread and the base fabric will narrow the stitching hole spacing, increasing the possibility of the stitched base fabrics separating and creating a gas leakage path. If the application width is too wide, the elasticity of the binder after curing may hinder the airbag from being folded and stored in the specified space. Furthermore, if the base fabric during the airbag sewing and binder application stages is made slightly larger (e.g., about 10 to 20 mm) than the final outer shape, and then re-cut to the final outer shape after the binder is applied and dried, this can prevent the binder from spreading too much after application and before drying, spilling from the edge of the base fabric and adhering to the applicator table, or the binder adhering to the table from re-adhering to unwanted locations during the application of the airbag itself or subsequent airbag application operations.

[0066] Furthermore, depending on the flatness of the bag body during application, the binder (2305) may slide across the bag surface immediately after application and spread into a horn-like shape, as shown in the lower right of Figure 23 . These horns occur and form randomly and intermittently. Their formation improves the adhesive strength between the binder and the base fabric after curing, thereby increasing the strength of the fabric constituting the base fabric near the seam. Increasing the overall application width of the binder itself raises concerns that the elasticity of the binder may impair the flexibility of the airbag bag body. Therefore, rather than widening the overall width, it is desirable to achieve a balance between strength and flexibility by providing horn-like portions. Intentional formation of horn-like portions can be achieved by locally increasing or decreasing the amount of binder dispensed, increasing or decreasing the thread tension (tension) during sewing to create ripples in the bag body after sewing, raising the edge of the base fabric during application, or creating a wavy shape on the application table surface.

[0067] <Effects of Embodiment 1> In the present invention, by allowing the binder to penetrate between at least some of the fibers that make up the suture in the sewn hole, the twist of the suture is tightened when the airbag inflates, preventing the generation of gaps between the sewn hole and the cross section of the base fabric through which the suture is inserted, thereby preventing leakage of inflation gas and achieving the desired inflation of the airbag.

[0068] <Embodiment 2> <Outline of embodiment 2> Mainly claim 2

[0069] In the airbag of embodiment 2, which is based on embodiment 1, at least a portion of the suture thread is exposed from the binder in a portion other than the sewn hole portion on at least one or more of the first base fabric or the second base fabric.

[0070] <Configuration of Embodiment 2> The suture of Embodiment 2, which is based on Embodiment 1, will be described using Figures 25 and 26. Figure 25 is a plan view of the seam as seen from the first backing fabric side, and Figure 26 is a cross-sectional view of the portion corresponding to A-A' in Figure 25, showing the cross section centered on the stitched hole portion indicated by B in Figure 25. Part B in Figure 25 (the portion where the stitched thread is interrupted) is the stitched hole portion, where the stitched thread on the first backing fabric side is pulled into the stitched hole by the stitched thread on the second backing fabric side and is therefore no longer visible from the first backing fabric side.

[0071] In Figure 25, binder (2505) is applied along the suture thread (2504) visible on the surface of the first backing fabric. If the amount of binder applied is insufficient to cover the suture thread, at least a portion of the suture thread (the portion indicated by (2608) in the figure) will be exposed from the binder, as shown in Figures 25 and 26. At the sewn hole, the thread on each backing fabric side is pulled into the hole by the thread on the opposite side, as shown in Figure 26. Therefore, the suture thread pulled into the sewn hole and the suture thread near the sewn hole are covered with binder. Figure 26 shows a case where there is a large amount of binder on the first backing fabric (2601) and a small amount of binder on the second backing fabric (2602). The binder is applied in an amount that minimizes seepage of the binder to the opposite side from the applied side. If the amount of application is such that at least a portion of the suture thread on the base fabric opposite the application side is exposed, when the bag body is placed on a table and the binder is applied, the possibility of the binder penetrating through the suture threads and stitching holes in the stitched part of the base fabric and adhering to the surface of the table can be reduced before the application of the applied surface is completed.

[0072] In addition to the amount of binder applied, when applying on one side, the binder must penetrate through the stitching holes and into the fibers that make up the suture on the opposite side, so a binder is selected that is not so viscous that it completely covers the suture on the applied side of the base fabric, nor is it so viscous that it covers the suture on the surface of the base fabric opposite to the applied side. The viscosity range of the binder when applying on both sides will be described later in embodiment 15. The viscosity range of the binder when applying on one side will be described later in embodiment 16.

[0073] Effect of Second Embodiment In the airbag of the second embodiment, when the binder is applied on a table, if the amount of application is such that at least a part of the suture thread on the base fabric side opposite to the application side is exposed, it is possible to reduce the possibility that the binder will penetrate the suture thread or stitching holes in the stitched portion of the base fabric and adhere to the surface of the table before the application of the surface to which the binder is applied is completed.

[0074] <Embodiment 3> <Outline of embodiment 3> Mainly claim 3

[0075] The airbag of embodiment 3, which is based on either embodiment 1 or embodiment 2, is configured so that in an area of ​​approximately the same width as the thickness of the suture thread along the sewing direction on the surface of one of the base fabrics on which the binder is applied to the seam of the base fabric, the two-dimensional area ratio of the suture thread at least partially exposed from the binder is greater than 0% and not more than 30%.

[0076] <Configuration of Embodiment 3> Figure 27 is a surface SEM photograph of the vicinity of the suture thread on the surface of a base fabric with a binder applied to the stitched portion. In the photograph of Figure 27, the white portion adhering to the suture thread and the fibers constituting the woven fabric of the base fabric is the binder. In the SEM photographs of Figure 27 and Figures 28 to 30 used in the explanation of the embodiment described below, the specifications of the suture thread on the base fabric side where the binder was applied are the same as those of the suture thread on the side where the binder was not applied. Nylon fibers are used, and a thread is used in which three small-diameter twisted yarns are further twisted together.

[0077] <Embodiment 3: Exposed Area Ratio of Suture from Binder> The area ratio of the white portion of the binder was determined within a region of approximately the same width as the thickness of the suture in the surface SEM photograph. The area ratio was determined by placing a rectangular frame (white frame in Figure 27) with a width approximately the same as the width of the suture and a length similar to the pitch of the suture on the image of the suture, and subtracting the area (number of pixels) of the binder within the frame from the area (number of pixels) of the frame, and dividing the result by the area (number of pixels) of the frame. In the example shown in Figure 27, the area ratio of the binder was 25.6%.

[0078] When the binder is applied only to one side of the base fabric, the two-dimensional area ratio of the suture thread at least partially exposed from the binder on the applied base fabric is greater than 0% and less than 30%. To prevent gas leakage from the seams when the airbag inflates, at least a portion of the fibers constituting the suture thread must be bound by the binder. Therefore, the area ratio must be less than 100%. Furthermore, if the amount of binder applied is such that more than 30% of the suture thread is exposed, the binder will not easily penetrate between the fibers of the suture thread on the opposite side of the base fabric, so the area ratio must be 30% or less. Note that if the area of ​​the suture thread exposed from the binder on the surface of the base fabric on which the binder is applied is 0%, this means that the suture thread is completely covered by the binder.

[0079] <Effects of Third Embodiment> In the airbag of the third embodiment, by specifying the two-dimensional area ratio range of the suture thread exposed from the binder on the base fabric on one side of which the binder is applied, it is possible to obtain an airbag in which the binder has penetrated into the spaces between the fibers of the suture thread on the base fabric on the side opposite to the side on which the binder is applied.

[0080] <Outline of Embodiment 4> The airbag of Embodiment 4, which is based on any one of Embodiments 1 to 3, is configured so that in an area of ​​approximately the same width as the suture thread (which may also include the suture thread from the opposite base fabric) along the stitching direction on the surface of one of the base fabrics on which no binder has been applied to the stitching portion, the two-dimensional area ratio of the portion covered with the binder (including both the suture thread and the base fabric) is 5% or more.

[0081] <Configuration of Embodiment 4> Figure 28 is a surface SEM photograph of the area around the suture on the surface of the base fabric on which no binder was applied to the stitched portion. In the photograph of Figure 28, the white area adhering to the suture and the fibers constituting the woven fabric of the base fabric is the binder. In the stitched hole shown in Figure 28, the suture from the base fabric on the opposite side is seen pulled out.

[0082] <Embodiment 4: Area ratio of the area of ​​the suture covered with the binder> The area ratio of the white portion of the binder was determined within a region of approximately the same width as the thickness of the suture (including the suture from the reverse base fabric) in the surface SEM photograph. Therefore, the area (number of pixels) of the binder attached to the surface of the base fabric near the suture is also included. The area ratio was determined by placing a rectangular frame (white frame in Figure 28) with a width approximately the same as the width of the suture, including the suture from the reverse base fabric, and a length similar to the pitch of the stitching, on the image of the suture, and dividing the area (number of pixels) of the binder within the frame by the area (number of pixels) of the frame. In the example shown in Figure 28, the area ratio of the binder was 11.7%.

[0083] When the binder is applied from only one side, the two-dimensional area ratio of the suture thread covered with the binder on the base fabric opposite to the base fabric coated with the binder (the base fabric not coated with the binder) is 5% or more. If the amount of penetration of the binder is such that the area ratio covered with the binder is less than 5%, there is a problem that the binder does not penetrate easily between the fibers of the suture thread on the side of the base fabric that was not coated with the binder. If penetration is poor, the binder may not be able to completely bind the fibers constituting the suture thread on the surface side of the base fabric opposite to the coated base fabric, and the twist may become tighter due to the tension when the airbag is inflated.

[0084] The upper limit of the area ratio covered by the binder is less than 100%. This is necessary to prevent the binder from penetrating the stitched holes and sutures and adhering to the surface of the table on which the bag is placed during application until the application is completed. The upper limit is preferably 80% or less, more preferably 70% or less.

[0085] <Effects of Embodiment 4> In the airbag of Embodiment 4, by specifying the two-dimensional area ratio range of the suture thread covered with the binder on the base fabric on the side where the binder is not applied, it is possible to obtain an airbag in which the binder has penetrated into the spaces between the fibers of the suture thread on the base fabric on the side where the binder is not applied.

[0086] <Outline of Embodiment 5> The airbag of Embodiment 5, which is based on any one of Embodiments 1 to 4, is configured so that the suture thread on the base fabric side on which the binder is applied has a cross-sectional area of ​​the binder that is 10% to 25% of the cross-sectional area of ​​the suture thread (55% to 100% of the cross-sectional area of ​​the portion other than the fiber in the cross-sectional area of ​​the suture thread).

[0087] <Configuration of Embodiment 5> Figure 29 is a cross-sectional SEM photograph of a sewn hole with a binder applied to one side from the upper base fabric side. The suture thread on the upper base fabric is pulled through the sewn hole to the lower base fabric side by the suture thread on the lower base fabric. In the photograph of Figure 29, the white areas adhering between the suture threads and between the base fabrics are the binder.

[0088] <Embodiment 5: Area ratio of binder in cross section of suture thread> The area ratio of the binder was determined relative to the cross-sectional area of ​​the suture thread on the upper base fabric (hereinafter referred to as upper thread) shown in Figure 29. It was determined as the ratio of the area of ​​the binder within the cross-sectional area of ​​a diameter of 500 µm of the upper thread (2904a) and the suture thread on the lower base fabric (hereinafter referred to as lower thread (2904b)) shown in Figure 29. The cross-sectional area of ​​the binder is 10% to 25% of the cross-sectional area of ​​the upper thread (2904a), which is a suture thread on a base fabric to which the binder is applied (55% to 100% of the cross-sectional area of ​​the portion other than the fiber in the cross-sectional area of ​​the suture thread (upper thread)). 29, the total cross-sectional area (number of pixels) of the binder relative to the total cross-sectional area (number of pixels) of the fibers constituting the upper thread (2904a) was 15.7%, and the cross-sectional area (number of pixels) of the portion other than the fibers in the cross-sectional area of ​​the upper thread (2904a) was 65%. Below the lower limit of the range, the binder is insufficient to bond the fibers together, and above that, the binder spreads from the applied side of the base fabric through the stitching holes and suture thread to the surface of the opposite side of the base fabric where the binder was not applied, and there is a possibility that the binder will adhere to the base that comes into contact with the surface of the lower base fabric.

[0089] <Effects of Embodiment 5> In the airbag of embodiment 5, by specifying the ratio of the cross-sectional area of ​​the binder to the cross-sectional area of ​​the suture thread, it is possible to obtain an airbag that is sufficient to bind the fibers that make up the suture thread and that does not allow the binder to seep widely onto the base fabric on the opposite side to the side where it is applied, thereby preventing the binder from adhering to the base.

[0090] <Outline of Sixth Embodiment> The airbag of Sixth Embodiment, which is based on any one of the first to fifth embodiments, is configured such that the suture thread on the side of the base fabric to which the binder has not been applied has a cross-sectional area of ​​the binder of 5% to 25% of the cross-sectional area of ​​the suture thread (35% to 100% of the cross-sectional area of ​​the portion other than the fiber in the cross-sectional area of ​​the suture thread).

[0091] <Configuration of Embodiment 6> Figure 29 is a cross-sectional SEM photograph of a sewn hole with a binder applied to one side from the upper base fabric side. The suture thread on the lower base fabric passes through the inside of the sewn hole and is pulled out to the lower base fabric side. In the photograph of Figure 29, the white areas adhering between the suture threads and between the base fabrics are the binder.

[0092] <Embodiment 5: Area Ratio of Binder in Cross Section of Suture> The area ratio of the binder area to the cross-sectional area of ​​the suture (hereinafter referred to as bobbin thread) on the lower base fabric shown in Figure 29 was calculated. This was calculated as the area ratio of the binder area within the cross-sectional area of ​​the upper thread (2904a) and bobbin thread (2904b) with a diameter of 500 μm shown in Figure 29. The total cross-sectional area of ​​the binder is 5% to 25% of the total cross-sectional area of ​​the bobbin thread, which is the suture on the base fabric to which the binder is applied (35% to 100% of the cross-sectional area of ​​the portion other than the fiber in the cross-sectional area of ​​the suture). In the example of Figure 29, the area (number of pixels) of the binder was 10.6% of the cross-sectional area (number of pixels) of the bobbin thread (2904b), and 44% of the cross-sectional area (number of pixels) of the portion other than the fiber in the cross-sectional area of ​​the bobbin thread (2904b). If the amount is below the lower limit of the above range, it will be insufficient to bond the fibers together, and if the amount is above the lower limit, the binder will adhere widely onto the uncoated side of the base fabric, and there is a possibility that the binder will adhere to the base that comes into contact with the uncoated side of the base fabric (lower base fabric).

[0093] <Effects of Sixth Embodiment> According to the airbag of the sixth embodiment, by specifying the ratio of the cross-sectional area of ​​the binder to the cross-sectional area of ​​the suture thread, it is possible to ensure that the binder is sufficient to bind the fibers that make up the suture thread and does not seep widely onto the base fabric on the opposite side to the side where it is applied, thereby preventing the binder from adhering to the base.

[0094] <Embodiment 7> <Outline of embodiment 7> Mainly claim 7

[0095] In embodiment 7, which is based on embodiment 1, when at least a portion of the seam of the first base fabric and / or the second base fabric is made of woven fabric, the fibers constituting the woven fabric near the seam are configured to be bound by a binder.

[0096] <Configuration of Embodiment 7> The stitching portion of Embodiment 7, which is based on Embodiment 1, will be described using Figures 5, 6a, and 6b. Figures 6a and 6b are cross-sectional schematic views of the stitched hole portion, and Figure 5 is a plan view schematic view showing the position CC' of the cross section of the stitched hole in Figure 6. Differences from Embodiment 1 will be described.

[0097] <Embodiment 7: First base fabric (0601), second base fabric (0602)> When at least a portion of the seam of the first base fabric and / or the second base fabric is made of a woven fabric, the fibers constituting the woven fabric of the seam of the first base fabric (0601) and the second base fabric (0602) near the seam are bound by a binder so as to be less likely to come undone.

[0098] The case where at least a portion of the seam of the first and / or second base fabric is made of woven fabric may mean that both base fabrics are entirely made of woven fabric, or that at least a portion of the seam in a nonwoven fabric is made of woven fabric, or that at least a portion of the seam in a single resin film is made of woven fabric. Even if at least a portion of the seam of both base fabrics is not made of woven fabric but is made of nonwoven fabric or knitted fabric, by binding the constituent fibers with a binder, it is possible to obtain the same effect that the binder makes it difficult for the fibers near the seam to unravel.

[0099] <Embodiment 7: Penetration of binder into woven fabric constituting the base fabric> Figures 6a and 6b show an example in which, after sewing together a first base fabric (0601) and a second base fabric (0602), a binder (0605) is applied to the vicinity of the stitching, including the suture thread (0604), and penetrates between at least some of the fibers (0603) of the suture thread (0604) and between the fibers (fibers not shown) constituting the woven fabric near the stitching, covering the stitching with the binder, and sealing the stitching holes in the stitching with the binder. Figure 6a is a cross-sectional view of the case where the binder has completely penetrated into the woven fabric constituting the base fabric, and Figure 6b is a cross-sectional view of the case where the binder has penetrated halfway into the woven fabric constituting the base fabric. In Figure 6a, the binder has completely penetrated into the base fabric, and the two base fabrics are integrated in the area where the binder has been applied, forming a strong structure. Even if the binder completely penetrates the woven fabric that makes up the base fabric, as shown in Figure 6a, if a base fabric with a coating agent pre-applied to the inside surface is used, the coating agent acts as a stopper for the binder, preventing the woven fabric that makes up the opposite side of the base fabric from being bonded to the binder. This leaves the first and second base fabrics joined only by the stitching thread and the binder at the sewn holes, resulting in an airbag that is more flexible and easier to bend than if the base fabrics were bonded together. The airbag can be stored more compactly. Depending on the specifications of the airbag, it is possible to choose whether to bond the base fabric at the seams to increase strength or to leave it unbonded for flexibility.

[0100] Alternatively, before sewing, a binder may be applied in a line to the intended sewing locations of each base fabric, allowing the binder to penetrate into the base fabric, and then the binder may be allowed to penetrate between at least some of the fibers, and the fabric may be sewn together using the resulting suture thread (0604).

[0101] In addition to the above method, other possible methods include applying a binder to the first base fabric and / or the second base fabric near the intended stitching portion before sewing, binding the fibers constituting the woven fabric that constitutes at least a part of the stitching portion of the base fabric with the binder, and then sewing the base fabric in this state, and then applying a binder (which may be made of a different material from the binder applied to the base fabric) to the stitching portion again, or applying a binder (which may be made of a different material from the binder that has been permeated between the fibers of the suture thread) to the vicinity of the stitching portion that has been sewn using a suture thread that has had the binder sufficiently permeated between the fibers in advance, and allowing the binder to permeate the fibers that make up the woven fabric near the stitching portion.

[0102] <Effects of Embodiment 7> According to the airbag of embodiment 7, the binder binds the fibers together so that the fibers constituting the woven fabric of the first base fabric and / or the second base fabric near the seams are less likely to unravel, thereby making it possible to better prevent leakage of airbag inflation gas from the seams.

[0103] <Embodiment 8> Mainly Claim 8 <Outline of Embodiment 8> In Embodiment 8, which is based on either Embodiment 1 or Embodiment 7, the binder used for the suture thread and the binder used for the first backing fabric and / or the second backing fabric are configured to be the same binder. <Configuration of Embodiment 8> In the airbag of Embodiment 8, which is based on either Embodiment 1 or Embodiment 7, the binder used for the suture thread and the binder used for the first backing fabric and / or the second backing fabric are configured to be the same binder. The configuration of Embodiment 8 will be explained using Figure 6, which was used to explain Embodiment 7.

[0104] <Embodiment 8: Binder (0605)> The binder (0605) is configured so that the binder used for the suture thread and the binder used for the first base fabric and / or the second base fabric are the same binder.

[0105] <Embodiment 8 Binder: Same Material> A binder (0605) is impregnated into the first base fabric (0601) and / or the second base fabric (0602) so that the fibers in the vicinity of the stitching portion are less likely to come undone. If a binder (0605) of the same material system as the binder (0605) impregnated between the fibers (0603) of the suture thread (0604) is used, the adhesion between the suture thread and the base fabrics will be better than if a binder of a different material system is used.

[0106] <Embodiment 8: Effect of Using the Same Binder Material> Using the same binder material between the corresponding suture thread and base fabric improves adhesion between the binder used in the suture thread and the binder used in the base fabric, preventing the binders that permeate each material from peeling or shifting due to the forces acting during airbag inflation. This prevents inflation gas leakage during airbag inflation due to misalignment between the suture thread (0604) and the base fabric at the seam, additional tension on the suture, and the stress on the woven fabric that constitutes the base fabric near the seam, which can cause fibers to unravel or misalign the warp and weft threads that make up the fabric, creating gaps in the base fabric. Reducing inflation gas leakage makes it easier to achieve the target reaction force characteristics (the force exerted by the airbag on the occupant) when designed, contributing to the airbag's intended purpose of protecting the occupant in an accident.

[0107] <Embodiment 8 Binder: Application Method> For example, after sewing, the binder can be applied from the first base fabric (0601) side so that it penetrates into the suture thread (0604) and the fibers constituting the woven fabric of the base fabric near the stitched portion, and after drying, the binder can be turned inside out and applied in the same way from the second base fabric (0602) side, thereby simultaneously applying both the suture thread (0604) and the base fabric. The order of application to the first base fabric (0601) side and the second base fabric (0602) side may be reversed. Different binders can also be used for the first base fabric (0601) side and the second base fabric (0602) side.

[0108] In addition, the first and second woven base fabrics may each be coated in advance with a resin to be used as a binder, the fibers that make up the base fabrics may be bound with the binder, and after sewing, the same resin as that used to coat the base fabrics may be applied as a binder.

[0109] <Embodiment 8: Binder: Pre-permeation into Suture Thread> As described in embodiment 1 using FIG. 22 , the suture thread can be pre-permeated with a binder before stitching. In this case, different binders (e.g., different viscosities) can be used for the upper and lower threads to permeate at least some of the inter-fiber spaces between the threads. After sewing the first and second base fabrics together using such an upper and lower thread, the same binder as that permeated into the fibers of the upper thread can be applied to the upper thread side, where the upper thread is visible except for the stitching holes, to permeate the inter-fiber spaces between the fibers that make up the base fabric. Similarly, the binder that permeated into the inter-fiber spaces between the fibers of the lower thread can be applied to the lower thread side to permeate the inter-fiber spaces between the fibers that make up the base fabric on the lower thread side. When different binders are used for the upper and lower thread sides, it is recommended to select materials that are primarily made of the same material, or to select binders that have good adhesive compatibility between the two binders.

[0110] Effect of Embodiment 8 According to the airbag of embodiment 8, the binder that has permeated between the fibers of the suture thread is the same as the binder that has permeated between the fibers that make up the base fabric. This improves the adhesion between the suture thread and the base fabric, reduces shifting of the stitched portion when the airbag is inflated, and reduces leakage of inflation gas.

[0111] <Embodiment 9> Mainly Claim 9 <Outline of Embodiment 9> Embodiment 9 is a manufacturing method for an airbag according to any one of Embodiments 1, 7, and 8, which includes a first base fabric impregnation step of impregnating a binder into a sewing thread from a seam of a first base fabric, and a second base fabric impregnation step of impregnating a second binder into a sewing thread from a seam of a second base fabric. A manufacturing method using double-sided application will be described.

[0112] <Ninth Embodiment Manufacturing Method> The manufacturing method of an airbag of the ninth embodiment will be described with reference to the flowchart shown in Fig. 7, the cross-sectional schematic diagram of the sewn hole portion C-C' after the first base fabric penetration step shown in Fig. 9, Fig. 8 showing the position C-C' of the cross section in Fig. 9, the cross-sectional diagram of the sewn hole portion after the second base fabric penetration step shown in Fig. 11, and Fig. 10 showing the position C-C' of the cross section in Fig. 11. The manufacturing method of the airbag of the ninth embodiment includes a second base fabric preparation step (S0701), a first base fabric preparation step (S0702), a sewing step (S0703), a first base fabric penetration step (S0704), and a second base fabric penetration step (S0705).

[0113] The second base fabric preparation step (S0701) involves preparing a sheet-like second base fabric, the first base fabric preparation step (S0702) involves preparing a sheet-like first base fabric, the sewing step (S0703) involves sewing the first and second base fabrics together to form a gas injection space, the first base fabric permeation step (S0704) involves permeating a first binder from the seam of the first base fabric into the sewing thread, and the second base fabric permeation step (S0705) involves permeating a second binder from the seam of the second base fabric into the sewing thread. If the permeation step of applying the binder is performed multiple times, such as by dividing the permeation step into separate applications or applying multiple layers, the process may be repeated after the second base fabric permeation step (S0705) to return to the step before the first base fabric permeation step (S0704). This is a method for manufacturing an airbag that involves a series of processes.

[0114] <Embodiment 9: First Base Fabric Preparation Step / Second Base Fabric Preparation Step> The second base fabric preparation step (S0701) is a step of preparing a sheet-like second base fabric for sewing to the first base fabric. "Preparing" refers to manufacturing the sheet-like second base fabric itself, cutting it to a size that can be handled by sewing manufacturing equipment, cutting it to an outer dimension that is the same as or slightly larger than the outer dimension of the product, or setting it in a predetermined location on the sewing manufacturing equipment (e.g., the loader section of the equipment, the starting position on the sewing table) for sewing. If the base fabric in the airbag product form is a coated fabric, the preparation process may include coating the second base fabric alone with a silicone resin or urethane resin before sewing (including before cutting). The "preparation" may also include starting the sewing equipment and setting the sewing thread. The first base fabric preparation step (S0702) is similar in content to the second base fabric preparation step (S0701). The order of the first and second fabric steps may also be reversed.

[0115] For the sake of explanation, in the following examples, the base fabric that is first permeated with the binder is referred to as the first base fabric. The second base fabric is placed on the table of the sewing device, and then the first base fabric is placed on top of the second base fabric (first base fabric preparation step / second base fabric preparation step). For fabrics with a front and back (e.g., fabric with one side coated), the base fabric is placed assuming that the side that will be on the outside when the product is completed is the one that will be on the outside. This is because there may be a process in which the bag is turned inside out after sewing into a bag. In that case, the side that will be on the inside of the completed bag is placed so that it will be on the outside when sewing. If the bag is not turned inside out after sewing, the side that will be on the outside of the bag is placed so that it will be on the outside when sewing.

[0116] When an airbag bag body is produced using a base fabric other than the first and second base fabrics, a step of preparing the corresponding base fabric is added. For example, when sewing multiple base fabrics together to produce a three-dimensional airbag bag body, base fabrics of different shapes are prepared and sewn together, so that the appropriate base fabric preparation step and sewing step are added and repeated depending on the type of base fabric. In the explanation of the present embodiment 9, an airbag made of two base fabrics, a first base fabric and a second base fabric, of approximately the same shape is used as an example.

[0117] <Embodiment 9: Sewing Step> The sewing step (S0703) is a process of sewing the first and second base fabrics together using a sewing thread in a predetermined stitching pattern. Sewing is generally performed using a sewing device such as a sewing machine, with an upper thread and a lower thread. In the case of multiple stitches (e.g., two rows), moving two needles of the sewing machine up and down simultaneously to create two parallel stitches makes it easier to maintain a constant distance between the stitches, allowing for stronger two-row stitching in a single stitching session. Note that multiple stitches may be sewn in one or more small rows rather than all at once.

[0118] <Embodiment 9: First Backing Fabric Infiltration Step> In the first backing fabric infiltration step (S0704), the first binder is infiltrated into the sewing thread from the seam of the first backing fabric. Whether the second backing fabric infiltration step or the first backing fabric infiltration step is performed first can be determined appropriately for each product.

[0119] After the suturing step (S0703), the sewn bag is moved from the suturing device to the table of the application device and set in a predetermined position. This setting operation may be included at the end of the suturing step. It is efficient to install the application device in an area that does not interfere with the suturing operation of the table of the suturing device and the table adjacent to it, and to move the bag by sliding it on the table.

[0120] The first binder is applied to the seam of the first base fabric and allowed to penetrate into the suture thread. As shown in the cross-sectional schematic diagram of the sewn hole in Figure 9, the first binder (0906) advances from the surface of the first base fabric located above toward the surface of the second base fabric (0902) directly above the base, penetrating into the fibers constituting the woven fabric of the first base fabric around the seam. It is preferable to select a material that dries quickly so that the first binder (0906) (or the resin constituting the first binder (0906) is polymerized, etc.) before reaching the surface of the second base fabric. The position of the sewn hole in Figure 9 is C-C' as shown in Figure 8. After the surface of the first binder has dried and is no longer sticky to the touch, the airbag with the first and second base fabrics sewn together is turned upside down so that the second base fabric (0902) is on top and the first base fabric (0901) is directly above the base. The operation of repeatedly turning the airbag after the first binder has been permeated from the first backing fabric side may be carried out at the beginning of the second backing fabric permeation step.

[0121] <Embodiment 9: Method of Applying Binder> When applying the binder in the first base fabric permeation step and the second base fabric permeation step described below, a dispenser or syringe that dispenses the binder may be used, a printing method such as silk screen printing may be used, an inkjet method may be used, or application may be by brush painting.

[0122] <Embodiment 9: Second Base Fabric Penetration Step> The second base fabric penetration step (S0705) follows the first base fabric penetration step and involves penetrating the second binder into the stitching thread at the seam of the second base fabric. This will be explained using Figure 11, which is a cross-sectional schematic diagram of the seam CC' in Figure 10. The second binder (1107) applied from the surface side of the second base fabric (1102) near the seam penetrates the stitching thread and also penetrates into the fibers that make up the woven fabric of the second base fabric at the seam. The penetrated second binder (1107) comes into contact with the previously applied first binder (1106) and becomes integrated.

[0123] <Embodiment 9: Second Backing Fabric Penetration Step: Application Table> In the second backing fabric penetration step, the binder application table may be provided with a notch or recess to allow the mounds of the first binder on the first backing fabric that have already been applied and dried to escape (e.g., Figures 9, 11, and 13). The height of the mounds after drying may be uneven. If the second backing fabric penetration step is performed using a dispenser that dispenses the second binder at a predetermined constant height, the distance between the second backing fabric and the dispenser may vary, resulting in a wide or narrow discharge width. This can be reduced by allowing the mounds of the first binder on the table to escape as described above. The binder application dispenser is provided with a sensor that measures the distance between the dispenser tip and the backing fabric surface. If the measured distance is controlled to be constant (including within a certain range), or if the measured distance is not affected by the mounds of the first binder, the application table does not need to have a notch or recess.

[0124] <Embodiment 9: Second Backing Fabric Penetration Step: Example of Alternative Application Method> Before the second binder is impregnated in the second backing fabric permeation step, the airbag, into which the first binder has been impregnated from the seams on the first backing fabric side, is turned upside down. However, if an opening can be provided on the base near the seams of the second backing fabric on the base side, and the second binder can be impregnated from the seams on the second backing fabric side through the opening using a dispenser or the like from below the base, the bag body does not need to be turned upside down. In this case, the directions in which the binder is applied for permeation differ between the first backing fabric permeation step and the second backing fabric permeation step.

[0125] If the first and / or second base fabrics are coated fabrics, it is preferable to use a binder made of the same type of material as the resin coated on each base fabric from the seam of each base fabric and allow it to penetrate into the suture. By selecting a binder material that matches the coating material of the coated fabric, it is expected that the adhesion of the base fabric edge facing the sewing hole through which the suture passes will be increased.

[0126] When different materials are used for the first binder and the second binder, including when the same type of material has a different viscosity, it is advisable to change the colors (e.g., red and blue) so that they can be easily distinguished visually. It is also advisable to change the colors of the first and second base fabrics or to change the colors of the suture threads (upper thread and bobbin thread during sewing) used on each base fabric so that they can be easily distinguished during the manufacturing process.

[0127] If the airbag has a three-dimensional sewn shape, it may not be possible to apply the binder to all the seams in one stroke and allow it to penetrate. In this case, an appropriate penetration step can be added.

[0128] <Effect of Double-Sided Application of Binder> The inventors measured the change in internal airbag pressure over time when the airbag was inflated in the following cases: a single-sided application of binder (dotted line); an application of binder to both the backing fabric and the opposite backing fabric (solid line); and an application of no binder to the seam (thin solid line). In Figure 19, the horizontal axis represents time (ms), with the inflator activation time at 0, and the vertical axis represents the internal airbag pressure (the upward direction of the vertical axis indicates the highest internal airbag pressure). During the "inflation time" shown in Figure 19, the airbag inflates as gas is released from the inflator, increasing the internal airbag pressure. After the airbag is fully inflated and the internal airbag pressure reaches its maximum, the inflation gas gradually escapes more slowly than in the case without binder application, causing the internal airbag pressure to decrease. When comparing two specifications where the only difference was the application surface conditions (one-sided application and two-sided application) after a certain time (restraint time) had elapsed since the airbag's maximum internal pressure (roughly 110 ms after the start of inflation (0 ms) required to protect the human body in a collision), the two-sided application maintained a slightly higher pressure than the one-sided application. By applying the binder to the seams on both sides, it was possible to reduce the leakage of inflation gas from the stitching holes.

[0129] Effect of Embodiment 9 According to the airbag manufacturing method of Embodiment 9, the first binder and the second binder are allowed to penetrate into the suture thread, thereby preventing the twist of the fibers of the suture thread from tightening and creating a gap between the suture thread and the base fabric at the sewn hole portion, thereby providing a manufacturing method for an airbag that is less likely to let out inflation gas.

[0130] <Embodiment 10> Mainly Claim 10 <Outline of Embodiment 10> Embodiment 10 is a method for producing an airbag based on embodiment 9, in which the first binder and the second binder have different viscosities.

[0131] <Embodiment 10: Reason for increasing the viscosity of the binder that is applied first> After the first binder is applied from the seam of the first base fabric to the seam thread, the fabric is turned over and the second binder is applied from the seam of the second base fabric to the seam thread. It is preferable that the viscosity of the first binder be higher than the viscosity of the second binder applied later. In the example shown in Figure 9, the first binder applied first from the upper first base fabric side penetrates the sewn hole, but only penetrates halfway through the thickness of the first base fabric. If the viscosity of the first binder that is applied first is lower, it may penetrate further to the surface of the second base fabric than in the example shown in Figure 9, and may reach the surface of the base and adhere to the base.

[0132] If the base on which the base fabrics are placed has holes, the first and second binders can be applied to the suture threads at the sewn portion after sewing the first and second base fabrics together, as opposed to the above example. For example, if the base for applying the binder has holes near the sewn portion and is configured to allow the binder to be applied from both above and below using a dispenser or the like, assuming the second base fabric is the base, the second binder applied to the suture threads from the second base fabric side should have a higher viscosity than the first binder applied to the suture threads from the upper first base fabric. This is because the binder is applied to the second base fabric from below, and therefore tends to drip away from the fabric (i.e., toward the dispenser or other application device). In this case, the second binder is applied and applied before the first binder is applied to the upper first base fabric. This is because if the first binder is applied from the top side first, there is a possibility that the first binder will reach the surface side of the second base fabric before the second binder is applied.

[0133] In particular, in the case of a material system in which the solvent inside the binder evaporates or otherwise escapes during hardening, even if binders of different viscosities are used, this is preferable because the first binder and the second binder have the same composition after hardening. When the viscosities of the first binder and the second binder are different, the area where the applied binder with a lower viscosity penetrates (in the direction along the plane of the base fabric and in the thickness direction of the base fabric) tends to spread more than the area where the applied binder with a higher viscosity spreads (see Figures 9 and 11).

[0134] Effect of Tenth Embodiment According to the method for manufacturing an airbag of the tenth embodiment, by making the viscosities of the first binder and the second binder different, it is possible to obtain a method for manufacturing an airbag that is easy to manufacture while maintaining the same inflation gas leakage characteristics as in the ninth embodiment.

[0135] <Embodiment 11> Mainly Claim 11 <Outline of Embodiment 11> Embodiment 11 is a method for manufacturing an airbag based on either embodiment 9 or embodiment 10, in which the viscosity of the first binder and the second binder is higher than that of the binder that is applied first.

[0136] <Embodiment 11: Viscosity of the Binder Applied First> When an airbag bag, consisting of a first base fabric and a second base fabric sewn together, is placed on a flat table, a binder is first applied from above the table, for example, and the binder is allowed to penetrate the stitching at the seams. If the binder penetrates through the seams and reaches the surface of the table, the binder will adhere to the surface of the table. If the next bag is placed on the table before the binder attached to the surface of the table has sufficiently dried, the binder attached to the surface of the table may be transferred to an unexpected location on the surface of the bag. This may result in a poor appearance of the bag, or may cause problems when folding the bag for storage if a lump of binder remains on the surface. Alternatively, even if the binder attached to the surface of the table is not transferred to another bag, it may remain attached to the surface of the table and harden, forming a convex portion. This may cause the surface of the base fabric above the convex portion to rise during binder application and come into contact with the application tool. Therefore, it is undesirable for the binder to adhere to the surface of the table.

[0137] Therefore, the binder applied first must have a viscosity that does not penetrate between the fibers that make up the suture thread in the sewn hole and into the gaps between the suture thread and the base fabric (including penetration into the woven fabric that makes up at least the vicinity of the seam of the base fabric), reaching the surface of the bag on the opposite side of the applied side by the time the initial application of the binder is completed. Conversely, the binder applied later must reach the point where the previously applied binder has penetrated into the gaps between the fibers that make up the suture thread in the sewn hole and between the suture thread and the cross section of the base fabric where the suture thread is inserted in the sewn hole, in order to achieve a sufficient binding effect. Therefore, it is preferable that the viscosity of the binder applied later be lower than that of the binder applied first. Furthermore, it is preferable that the first and second binders be made of the same material but with different viscosities, as this improves adhesion between the two.

[0138] Because the previously applied binder seals the sutures and stitched holes on the side closest to the base fabric to which the binder was applied, the binder applied later can be a resin with a lower viscosity than the binder used for single-sided application. Therefore, in principle, the next binder application is performed after the relatively high-viscosity binder applied earlier has reached a state sufficient to prevent the next binder from reaching the base surface. The time required to reach this state is determined appropriately based on the size of the airbag and the sewing method of the suture (e.g., the number of stitches, such as one or two, or the length of the stitches). Furthermore, to shorten the application time, low-viscosity binders may be applied using a method such as spray application, which applies a certain amount of application pressure (higher than natural dripping) to the binder during application.

[0139] <Embodiment 11: Benefits of High Viscosity of Binder Applied First> A binder with a high viscosity of the same material system generally has a higher viscosity than a binder with a low viscosity because it contains less solvent. If the amount of solvent is small, the time it takes for the solvent to evaporate after application and the binder to dry (at least the surface is dry and hardened to the extent that it does not adhere to other surfaces) is shorter than that of a binder with a low viscosity. If the drying time of the high-viscosity binder applied first is shorter than that of the low-viscosity binder applied later, this is advantageous when repeatedly applying the binder to both sides of the bag. In particular, a high-viscosity binder applied first has the effect of shortening the time it takes for the surface of the binder to dry and become non-sticky to the touch after application, and the effect of shortening the drying time until the surface is at least non-sticky to the touch, even when a drying process using an infrared heater or hot air is performed after application.

[0140] Conversely, even when the binder is applied from below through the hole in the base as in the modified example described in embodiment 10, it is better for the binder on the bottom to have a higher viscosity, and therefore it is better to apply it first. As described above, if the viscosity of the binder on the bottom is low, it is likely to drip from the tip of the dispenser toward the dispenser body below, and if the viscosity of the binder on the top is low and it is applied first, the binder applied from above may permeate the area where the binder on the bottom should be applied, and it may not be possible to apply the binder on the bottom properly.

[0141] <Effects of Eleventh Embodiment> According to the airbag manufacturing method of the eleventh embodiment, by making the viscosity of the binder that is applied first higher than the viscosity of the binder that is applied later, it is possible to provide a manufacturing method of an airbag that can apply the binder well.

[0142] <Embodiment 12> Mainly Claim 12 <Outline of Embodiment 12> Embodiment 12 is a method for manufacturing an airbag based on any one of embodiments 9 to 11, in which a relatively viscous binder that is applied first is applied to the upper thread side that is bound to the lower thread on the surface of the base fabric by passing a single stitch of suture thread through the base fabric.

[0143] <Embodiment 12: Method of Applying Binder> The binder may be transferred to an application device separate from the sewing device after sewing and then applied, or it may be manufactured using a dual-purpose machine equipped with an application tool or device so that the binder is applied to the sewn portion while the bag is still placed on the table of the sewing device. To accommodate a variety of airbags with a variety of stitching methods using a single application device, for example, it is not possible to provide holes (or cutouts) in the table that correspond to the stitching patterns, so the bag is placed on a flat table and applied. In this case, the application is started from the upper base fabric side that is visible on the table, and after the upper side is applied and dried, the bag is turned over and applied to the other side.

[0144] An airbag of Example 12 will be described using Figures 14-16. Figure 14 shows a schematic plan view of the sewn portion as seen from the upper thread (1404a) side. Figure 15 shows a schematic vertical cross-sectional view of the portion indicated by A-A' in Figure 14. Figure 16 shows a schematic cross-sectional view of the portion indicated by C-C' in Figure 14. When sewing the airbag of Example 7, as shown in the schematic vertical cross-sectional view of Figure 15, the upper thread (1504a) penetrates the first base fabric (1501) and the second base fabric (1502) and is pulled out and fixed to the surface of the second base fabric (1502) on the lower thread (1504b) side (in the description of Example 12, the first base fabric is the upper thread (1504a) side, but the reverse is also possible). The airbag of Example 12 is manufactured by a manufacturing method in which the base fabric (e.g., the first base fabric (1501)) that was positioned upper on the sewing table during sewing is first coated. As shown in FIG. 16, the upper thread (1604a) is pulled out to the vicinity of the surface of the lower base fabric (1602) and passes through the two base fabrics.

[0145] Therefore, when the first binder (1606) is applied to the suture thread (upper thread) (1604a) of the seam from the upper thread (1604a) side and allowed to penetrate between the fibers, it is more likely to penetrate through the hole in the seam toward the second base fabric (1602) than when the upper thread and lower thread are near the boundary between the first and second base fabrics as in Figure 9. By using a binder with a higher viscosity than the second binder (1607) to be applied next as the first binder, it does not penetrate to the surface of the base fabric on the lower thread (1604b) side, but it is more likely to penetrate into the fibers of the upper thread because there is only the upper thread in the hole in the seam than when it is penetrated into a seam where the lower thread is not strong (normal, or the upper thread is strong. Examples of normal cases: Figures 2 and 4).

[0146] In the description of this embodiment, the thread indicated by the symbol 1504a in FIG. 15 is the upper thread, and the thread indicated by the symbol 1504b is the lower thread. However, the configuration may also be such that 1504a is the lower thread and 1504b is the upper thread, and the binder with a relatively high viscosity is applied first from the lower thread side of 1504a.

[0147] <Effects of Embodiment 12> According to the airbag manufacturing method of Embodiment 12, even if a binder with a high viscosity is used as the binder that is applied first, it can be sufficiently permeated into the suture thread on the applied side.

[0148] <Embodiment 13> <Outline of Embodiment 13> Embodiment 13 is a method for manufacturing an airbag according to Embodiment 1, which comprises applying a binder to stitched portions on the surface of either the first base fabric or the second base fabric, allowing the binder to penetrate through the stitched holes and into spaces between the fibers that hold the stitching thread in the stitched holes, and allowing the binder to penetrate into at least some of the spaces between the fibers that make up the stitching thread exposed between the stitched holes on the surface of the base fabric opposite to the side where the binder was applied.

[0149] <Manufacturing Method of Embodiment 13> The manufacturing method of the airbag of Embodiment 13 will be described using the flowchart shown in Fig. 30, the schematic plan view of the seam of the base fabric on the side where the binder is applied shown in Fig. 25 (in this embodiment 13, an example in which the binder is applied to the first base fabric side will be described), and the schematic vertical cross-sectional view of the seam shown in Fig. 26. The manufacturing method of the airbag of Embodiment 13 comprises a binder permeation step (S3001) and a binder permeation step (S3002) of the reverse base fabric side suture thread fiber.

[0150] The binder penetration step (S3001) involves applying a binder to the stitched portion on the surface of either the first or second backing fabric, and then penetrating the binder through the stitched holes in the stitched portion to the fibers constituting the suture within the stitched holes. The reverse backing fabric suture fiber binder penetration step (S3002) involves penetrating the binder through the stitched holes to at least some of the fibers constituting the suture (different from the suture exposed between the stitched holes on the application-side backing fabric surface) exposed between the stitched holes on the backing fabric surface opposite the backing fabric to which the binder was applied. If the binder application penetration step is performed multiple times, such as by dividing the application or applying multiple layers, the process may be repeated after the reverse backing fabric suture fiber binder penetration step (S3002) to the step before the binder penetration step (S3001), as shown in FIG. This is a method for manufacturing an airbag that involves a series of processes.

[0151] <Embodiment 13: Binder penetration step (S3001)> In the "binder penetration step" (S3001), a binder is applied to the stitched portion on the surface of either the first or second base fabric from the surface side of the base fabric. This is a step in which the applied binder penetrates through the stitched hole in the stitched portion and into the spaces between the fibers that make up the suture thread within the stitched hole. When the binder penetrates into the spaces between the fibers that make up the suture thread, the binder penetrates between the fibers and bonds at least some of the fibers together, as shown in the schematic diagrams of Figures 17 and 18 or the cross-sectional SEM photograph of Figure 29.

[0152] The binder that has penetrated into the sewn hole penetrates through the gaps between the cross sections of the first and second base fabrics at the sewn hole and the suture thread, or through the fibers of the suture thread, and penetrates to the surface of the base fabric on the opposite side to the applied base fabric (if applied from the surface of the first base fabric, to the surface of the second base fabric on the opposite side).

[0153] <Embodiment 13: Reverse base fabric side suture fiber binder penetration step (S3002)> In the "reverse base fabric side suture fiber binder penetration step" (S3002), the binder that has penetrated through the sewn hole to the surface of the base fabric opposite to the base fabric to which the binder has been applied (the second base fabric in this embodiment 13) exits the sewn hole to the surface side of the second base fabric, and penetrates through the surface of the second base fabric to at least some of the spaces between the fibers that make up the suture connecting the sewn holes. The penetration of the binder between the fibers that make up the suture occurs when the binder moves through the tiny gaps between the fibers by capillary action.

[0154] In the above example, the application of the binder is described only from the first base fabric side, but it is also possible to apply the binder from the first base fabric side, and after hardening after the reverse base fabric side suture thread fiber binder penetration step, to further apply the binder from the second base fabric side.

[0155] As in the present embodiment 13, the binder penetrates into at least some of the spaces between the fibers constituting the suture between the sewn holes on the surface of the base fabric opposite to the side to which it is applied, thereby binding not only the fibers constituting the suture on the surface of the base fabric opposite to the side to which it is applied, but also at least some of the fibers constituting the suture on the side opposite to the side to which it is applied. As a result, the tension generated in the suture tightens the twist, making it less likely that gaps will form between the suture and the base fabric at the sewn holes in the sewn portions.

[0156] In the airbag manufacturing method of embodiment 13, when the binder is applied from only one side, the lower limit of the viscosity of the applied binder is preferably higher than the viscosity of the binder applied later when applying from both sides. In the case of application from both sides, the sutures and sewn holes close to the base fabric side to which the binder was applied first are bound by the binder that was applied first and hardened, making them less susceptible to penetration, and the binder applied later is stopped by the binder that was applied earlier. In the case of application from only one side, the applied binder is not stopped, so the lower limit of the viscosity is set high to prevent excessive penetration into the base fabric side opposite the side to which the binder was applied.

[0157] Effect of Embodiment 13 In the airbag manufacturing method of Embodiment 13, even when one-side application is used instead of two-side application, the fibers constituting the suture between the sewn holes on the surface of the base fabric opposite the side where the binder is applied can be bound together with the binder. As a result, it is possible to make it less likely that gaps will form between the suture and the cross section of the base fabric where the suture passes through the sewn holes in the sewn portions.

[0158] <Embodiment 14> <Outline of Embodiment 14> Based on the airbag manufacturing method of Embodiment 13, the method further includes an inter-base fabric bonding step in which a portion of the binder that has permeated through the sewn hole accumulates between the first base fabric and the second base fabric, bonding the first base fabric and the second base fabric together.

[0159] <Manufacturing Method of Embodiment 14> A manufacturing method for an airbag of this embodiment 14, which is based on the manufacturing method of embodiment 13, will be described with reference to Fig. 31. As shown in Fig. 31, in addition to the steps of the manufacturing method of embodiment 13, a step of bonding base fabrics together (S3103) is further included. The steps other than the step of bonding base fabrics together (S3103) are the same as those of embodiment 13, and therefore description thereof will be omitted.

[0160] <Embodiment 14: Inter-Base Fabric Bonding Step (S3103)> The "inter-base fabric bonding step" (S3103) is configured to apply a binder to the seam on the surface of either the first or second base fabric, and a portion of the binder that penetrates through the stitching holes in the seam accumulates between the first and second base fabrics, bonding the first and second base fabrics together. In the binder penetration step (S3101) and the reverse-base fabric suture fiber binder penetration step (S3102), the binder penetrates at least some of the spaces between the stitching holes and the fibers that make up the suture. As the binder hardens, the binder that has accumulated between the first and second base fabrics also hardens to bond the first and second base fabrics together near the stitching holes. If the binder is a thermosetting resin, the binder hardens by heating and maintaining a predetermined temperature after penetration. If the binder is a photocurable resin, it is cured by irradiating it with a predetermined wavelength of light for a predetermined cumulative amount of light, or by other methods and conditions suited to the resin that constitutes the binder.

[0161] Figure 32 is a cross-sectional schematic diagram of a stitched hole along the direction of the stitching in embodiment 14. In the example of Figure 32, a binder is applied to the stitched portion on the surface of the first base fabric (3201). The binder (3205) penetrates through the stitched hole and the stitching thread to the surface side of the second base fabric (3202). The binder also spreads from the stitched hole and accumulates between the first base fabric (3201) and the second base fabric (3202). When the binder (3205) hardens, the first base fabric and the second base fabric are bonded together.

[0162] Figure 29 is a cross-sectional SEM photograph of an airbag manufactured by the manufacturing method of the present invention, taken across the direction of the seams. In this example, unlike the schematic diagram of Figure 32, the upper seam (2904a) in Figure 29 is pulled by the lower seam (2904b) and drawn toward the second base fabric (2902). The photograph also shows that the binder has accumulated between the first base fabric (2901) and the second base fabric (2902), bonding the two base fabrics together near the seam holes.

[0163] The binder that permeates through the sewn holes and accumulates between the first and second base fabrics near the seams bonds the two base fabrics together, making it less likely that a gap will form between the first and second base fabrics when the airbag is inflated by gas injection, and less likely that inflation gas will leak through that gap. Furthermore, by bonding the two base fabrics together near the sewn holes, including the stitching at the sewn holes, it is possible to prevent the stitching from moving at the sewn holes when the airbag is inflated. This prevents the stitching from moving and creating a gap between the first and second base fabrics.

[0164] The manufacturing method of this embodiment 14 can be applied to the airbag of embodiment 1 so that a portion of the binder that has penetrated through the sewn holes accumulates between the first and second base fabrics, bonding the first and second base fabrics together.

[0165] Effect of Embodiment 14 By using the airbag manufacturing method of Embodiment 14, the first base fabric and the second base fabric are bonded together, which reduces the likelihood of gaps forming between the first base fabric and the second base fabric when the airbag is inflated by gas injection, making it less likely that inflation gas will leak through those gaps. Furthermore, by bonding the two base fabrics together near the sewn holes, including the stitching at the sewn holes, it is possible to prevent the stitching from moving at the sewn holes when the airbag is inflated. This prevents the stitching from moving, which would otherwise cause gaps to form between the first base fabric and the second base fabric.

[0166] <Embodiment 15> Mainly Claim 15 <Outline of Embodiment 15> Embodiment 15 is a manufacturing method for an airbag based on any one of Embodiments 9 to 12, in which the viscosity of the binder when applied is measured in Pascal-seconds, and the viscosity of the high-viscosity binder and the viscosity of the low-viscosity binder range from 3.0 mPa·s to 90 Pa·s.

[0167] <Embodiment 15: Viscosity of Binder> The viscosities of the first binder and the second binder are measured in Pascal seconds, with the viscosity range of the high-viscosity binder and the low-viscosity binder ranging from 3.0 mPa·s to 90 Pa·s. Figure 20 shows the relationship between binder viscosity and airbag gas retention. The horizontal axis represents binder viscosity, and the vertical axis represents airbag gas retention. These are test results in which materials of the same viscosity were applied to both sides of the airbag seam. Binders with viscosities between 0 and less than 3.0 mPa·s and exceeding 90 Pa·s are difficult to manufacture when dispensed using a commonly used pneumatic dispenser. Binders with viscosities of 0 to less than 3.0 mPa·s have too low a viscosity, making it difficult to control the amount dispensed using air pressure, and they tend to spread over the surface of the base fabric and easily leak to the back of the base fabric. Binders with viscosities exceeding 90 Pa·s are too viscous to be extruded using air pressure, making them difficult to dispense. A viscosity in the range of 3.0 mPa·s to 90 Pa·s provides good manufacturability.

[0168] <Embodiment 15: Viscosity of Binder: Experimental Results> As described in Embodiment 4, the inventors of the present application investigated the conditions under which the internal pressure of an airbag after inflation is less likely to decrease. They found that applying a binder to the seam reduces the decrease in internal pressure of the airbag, and that applying the binder to both sides of the seam reduces the decrease in internal pressure more than applying it to one side. Next, they conducted an experiment by varying the viscosity of the binder applied to both sides, and found that a higher viscosity binder applied first was more preferable. Specifically, the viscosity should be on the low side of the above-mentioned viscosity range. Preferably, the viscosity H of the first-applied binder is in the range of 1.0 to 20 Pa·s, and the viscosity L of the second-applied binder is in the range of 1.0 mPa·s to 1.0 Pa·s (provided that H>L). More preferably, the viscosity of the first-applied binder is in the range of 1.5 to 4.0 Pa·s, and the viscosity of the second-applied binder is in the range of 100 to 600 mPa·s. When the binder had a viscosity higher than 90 Pa s, the pressure inside the airbag decreased quickly. It is speculated that this was because the binder with a high viscosity became harder than binders within the preferred range after drying and hardening, which made it easier for cracks to form in the binder at the sewn holes when the airbag was inflated, causing the inflation gas to leak through these cracks.

[0169] Effect of Embodiment 15 In the method for producing an airbag according to Embodiment 15, by setting the binder viscosity within the above range, the method can be one that provides good application properties during production and facilitates production.

[0170] <Embodiment 16> Mainly Claim 16 <Outline of Embodiment 16> Embodiment 16 is a manufacturing method for an airbag based on any one of Embodiments 13 to 14, in which the viscosity of the binder when applied is in Pascal-seconds and falls within the range of 3.0 mPa·s to 90 Pa·s.

[0171] <Embodiment 16: Viscosity of Binder> The viscosity of the binder is measured in Pascal-seconds, with the viscosity range of high-viscosity binders and low-viscosity binders being 3.0 mPa·s to 90 Pa·s. Figure 19 shows the internal airbag pressure (vertical axis) versus time (horizontal axis: ms) when the airbag is inflated. The figure shows test results for three airbags with different binder coating specifications: double-sided coating (thick solid line), single-sided coating (thick dotted line), and no binder coating (thin solid line). The maximum internal airbag pressure was split evenly between the cases with and without binder coating. During the restraint time after the airbag is fully inflated, the double-sided coating maintained the internal airbag pressure better than the single-sided coating. However, the difference is small, and considering the difference in manufacturing costs between double-sided and single-sided coating, the airbag can be designed to accommodate this difference.

[0172] If a binder with a low viscosity range, such as less than 3.0 mPa·s, is used to apply to the base fabric of a bag body that has not been coated with a binder, the applied binder will penetrate from the application side surface of the base fabric placed on the table of the application device through the stitched holes or sutures before the binder is completely applied to the base fabric, and the binder will reach the surface of the table. If the binder reaches the surface of the table and adheres to it, it may re-adhere to unwanted areas on the surface of another base fabric to be coated next, causing problems. If the binder adheres to the stitched holes or on the surface of the base fabric that contacts the surface of the table, it may hinder the penetration of the applied binder. Therefore, binders with a viscosity range of less than 3.0 mPa·s are not used, and binders with a viscosity of 3.0 mPa·s to 90 Pa·s are used.

[0173] When the binder is applied to one side, the viscosity of the binder is preferably 3.0 mPa·s to 15 Pa·s, more preferably 3.0 mPa·s to 10 Pa·s, within the above range. The most preferred viscosity is 3.0 mPa·s to 3.0 Pa·s. Within this range, even when the binder is applied to only one side, it can penetrate at least some of the fibers constituting the suture thread exposed between the stitching holes on the surface of the base fabric opposite to the coated base fabric.

[0174] Effect of Sixteenth Embodiment In the sixteenth embodiment, by using a binder having a viscosity of 3.0 m to 90 Pa·s as the binder, the coating property during production is good, and a production method that is easy to produce can be achieved.

[0175] <Effects> The present invention is configured such that at least a portion of the fibers of the suture thread in the sewn hole are bound with a binder, thereby making it less likely that gaps will form between the suture thread and the cross section of the base fabric where the suture thread passes through at the sewn hole when the twist of the suture thread tightens during airbag inflation. This is because the presence of a binder layer between the fibers makes it less likely that the spacing between the fibers will narrow. In this way, when a binder is applied to a seam configured to make it less likely that gaps will form between the suture thread and the base fabric in the sewn hole, the percentage of the suture exposed from the binder in areas on the base fabric other than the sewn hole and the percentage of the suture thread covered with the binder are specified to prevent the binder from adhering to the base on the opposite side to the surface where it is applied. The area ratio of the cross section of the suture thread (ratio of the cross-sectional area of ​​the binder to the cross-sectional area of ​​the thread) is specified for the ratio of the binder between the fibers that make up the suture thread.In addition, to optimize the viscosity of the binder, the binder (corresponding to the "coating agent" in Patent Document 1) is not applied from just one side, but is applied from both sides, and the binder applied first is configured to have a higher viscosity than the binder applied on the opposite side.This makes it possible to prevent the binder from adhering to the support base through the bag body and the seams of the bag body during operation.

[0176] By specifying the viscosity when applying on one side, the seam can be sealed efficiently, the flow of the binder onto the surface of the base fabric opposite to the applied surface can be adjusted, and a predetermined rate of binder can be dispersed between the fibers that make up the suture thread.When applying on both sides, by using a binder with a lower viscosity than the binder initially applied as the binder applied to the other side later, the binder can more easily penetrate between the fibers that make up the twisted yarn and become integrated with the binder initially applied, allowing for efficient sealing of the seam.Furthermore, as a result of the tightening of the "twist" of the fibers of the twisted suture thread, it is possible to provide a method for manufacturing an airbag body that can bind at least some of the fibers that make up the suture thread so that gaps are less likely to form between the suture thread and the cross section of the base fabric where the suture thread passes through at the sewn hole.

[0177] First base fabric...0201 Second base fabric...0202 Fiber...0203 Suture thread...0204 Binder...0205

Claims

1. An airbag comprising a sheet-like first base fabric, a sheet-like second base fabric, and a sewing thread which is formed by twisting and bundling a number of fibers together to form a gas injection space between the first base fabric and the second base fabric and sewing the two together to form a seam, wherein at least some of the fibers of the sewing thread are bound together with a binder so that voids are unlikely to form between the sewing thread and the base fabrics at the sewn hole of the seam as a result of the tension generated in the sewing thread tightening the twist.

2. The airbag according to claim 1, wherein at least a portion of said sewing thread is exposed from said binder in at least a portion of either the first base fabric or the second base fabric other than the sewn holes.

3. The airbag as described in claim 2, wherein in an area of ​​approximately the same width as the thickness of the sewing thread along the sewing direction on the surface of one of the base fabrics on which the binder is applied to the seam of one of the base fabrics, the two-dimensional area ratio of the sewing thread at least partially exposed from the binder is greater than 0% and less than 30%.

4. An airbag as described in claim 2, wherein in an area of ​​approximately the same width as the suture thread (which may include the suture thread from the opposite base fabric) along the sewing direction on the surface of one of the base fabrics on which no binder has been applied to the seam of the other base fabric, the two-dimensional area ratio of the portion covered with the binder (including both the suture thread and the base fabric) is 5% or more.

5. An airbag as claimed in claim 1 or claim 2, wherein the sewing thread on the base fabric side to which the binder is applied comprises a cross-sectional area of ​​the binder of 10% to 25% of the cross-sectional area of ​​the sewing thread (55% to 100% of the cross-sectional area of ​​the portion of the sewing thread other than the fibers).

6. An airbag as claimed in claim 1 or claim 2, wherein the sewing thread on the side of the base fabric to which no binder has been applied comprises a cross-sectional area of ​​the binder of 5% to 25% of the cross-sectional area of ​​the sewing thread (35% to 100% of the cross-sectional area of ​​the portion of the sewing thread other than the fibers).

7. An airbag as claimed in claim 1, wherein when at least a portion of the seams of the first base fabric and / or the second base fabric are made of a woven fabric, the fibers constituting the woven fabric in the vicinity of the seams of the first base fabric and / or the second base fabric are bound with a binder so as to make the fibers constituting the woven fabric at the seams of the first base fabric and / or the second base fabric less likely to come undone.

8. The airbag according to claim 7, wherein the adhesive used for the stitching thread and the adhesive used for the first base fabric and / or the second base fabric are the same adhesive.

9. A method for manufacturing an airbag as claimed in claim 1, comprising: a first base fabric permeation step of permeating a first binder from the seam of a first base fabric into the sewing thread; and a second base fabric permeation step of permeating a second binder from the seam of a second base fabric into the sewing thread.

10. The method for manufacturing an airbag according to claim 9, wherein the first binder and the second binder have different viscosities.

11. The method for manufacturing an airbag as described in claim 10, wherein the first binder and the second binder are applied on a flat table, and the first of the two binders to be applied has a higher viscosity than the second binder to be applied.

12. The method for manufacturing an airbag according to claim 11, wherein the relatively highly viscous binder is applied first to the upper thread side which is bound to the lower thread on the surface of the base fabric by a single thread of sewing applied to the base fabric.

13. A method for manufacturing an airbag as described in claim 1, comprising: a binder penetration step of applying a binder to a stitched portion on the surface of either a first base fabric or a second base fabric, and penetrating the binder from a stitched hole in the stitched portion between the fibers constituting the stitching thread in the stitched hole; and an opposite base fabric suture fiber binder penetration step of penetrating the binder from the stitched hole into at least some of the spaces between the fibers constituting the stitching thread exposed between the stitched holes on the surface of the base fabric opposite to the base fabric to which the binder is applied (a different suture thread from the suture exposed between the stitched holes on the surface of the applied base fabric).

14. The method for manufacturing an airbag as claimed in claim 13, further comprising a step of bonding the first and second base fabrics together, wherein a portion of the binder that has seeped through the sewn holes accumulates between the first and second base fabrics to bond the first and second base fabrics together.

15. A method for manufacturing an airbag according to any one of claims 9 to 12, wherein the viscosity of the binder when applied is in Pascal-second units, and the viscosity range of the high-viscosity binder and the low-viscosity binder is 3.0 mPa·s to 90 Pa·s.

16. The method for manufacturing an airbag according to claim 13 or 14, wherein the viscosity of the binder when applied is in the range of 3.0 mPa·s to 90 Pa·s in Pascal seconds.

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