Airbag manufacturing method with improved internal pressure retention performance

Abstract

Provided is a production method for an airbag that has high internal-pressure retaining performance, is low-cost, is highly producible, and is excellent in compactness. The production method according to the present invention is a manufacturing method for an airbag formed by stitching at least one pair of base fabric panels at the peripheral edges thereof. The production method includes: a fusion-bonding step for fusion-bonding the first surface layer to the inner surfaces of the base fabric panels by applying heat or ultrasonic waves from the outside of the pair of base fabric panels while applying a tensile force to a strip-shaped impermeable film type protection material that has been center-folded, comprises a laminated resin film including a first surface layer and a second surface layer, and is located between the inner surfaces of the respective base fabric panels, and while the strip-shaped impermeable film-type protection material is continuously inserted along the linear or curved peripheral edges of the pair of base fabric panels, and in this step, the second surface layer peels when the second surface layer is not fusion-bonded to itself by thermal fusion-bonding or ultrasonic fusion-bonding, or when a strong tensile force is applied to the pair of base fabric panels; and a stitching step for stitching the pair of base fabric panels in the vicinity of a bonding region before, after, or simultaneously with bonding. Said production method also executes, in two stages, the bonding of one of the base fabric panels, the protection material, and the other of the base fabric panels.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing an airbag used in an airbag system installed in a vehicle. More specifically, it relates to a method for manufacturing an airbag in which the outer edges of a pair of base fabric panels are sewn together, and which has improved internal pressure retention performance. [Background technology]

[0002] Traditionally, airbags used in vehicle airbag systems have involved creating a bag-like structure by sewing together the outer edges of a pair of base fabric panels, into which gas is instantaneously injected to inflate and deploy. However, since sewing is usually done using sewing machine thread, gas leakage between the pair of base fabric panels and through the holes of the sewing machine needle is unavoidable.

[0003] Today, various types of airbags are used depending on their location in the vehicle, including PAB (Passenger Airbag), DAB (Driver Airbag), SAB (Side Airbag), KAB (Knee Airbag), CAB (Curtain Airbag), and pedestrian airbags. Airbags absorb impact to the human body by retaining the injected gas. In particular, while DABs generally meet performance requirements if they can cope with instantaneous impact (first impact), CABs, for example, need to maintain their inflation state even during vehicle rotation (rollover) after the first impact, requiring the internal pressure of the airbag to be maintained at a constant level (e.g., 30 kPa) or higher for an extended period (e.g., 6 seconds) (i.e., internal pressure maintenance). Furthermore, pedestrian airbags require longer internal pressure maintenance compared to DABs, etc., because the timing of pedestrians running onto the hood and colliding with the vehicle body (e.g., the pillar) varies.

[0004] To meet the requirements for maintaining internal pressure, the following methods have been considered. One method involves bonding the outer edges of a pair of base fabric panels with adhesive instead of sewing. While this method can suppress gas leakage, the absence of sewing means that the adhesive may not withstand the strength required when the airbag deploys.

[0005] Another method involves manufacturing a pair of base fabric panels using OPW (One Piece Woven) and coating the outside of the base fabric. While this method offers airtightness and strength without the need for stitching and due to the coating, it has drawbacks: it is difficult to create complex shapes, the coating needs to be applied relatively thickly, which tends to increase the weight of the airbag, and it is also costly.

[0006] Another method involves bonding the outer edges of a pair of base fabric panels with silicone adhesive and then sewing the bonded area. While this method can suppress gas leakage and ensure strength, it has drawbacks such as low productivity and a thicker bonded area, which worsens the foldability and storage capacity of the airbag. Additionally, the weight of the silicone adhesive increases the weight of the airbag. As illustrated in Figure 2, in this method, the silicone adhesive stretches when the airbag deploys, preventing gas from accessing the seams. Generally, silicone adhesives are suitable for this application because they provide high bonding strength to the base fabric panel. However, they take half a day to about a day to cure, resulting in low productivity. Furthermore, for example, the folded thickness of a pair of base fabric panels is 2.2 mm in areas without adhesive (areas where internal pressure retention is not required), while the folded thickness in areas with adhesive and stitching is 5.2 mm, resulting in a lack of compactness (foldability and storage). In addition, silicone adhesives need to be separated from the airbag fabric during recycling, and their production generates relatively high levels of GHG (Green House Gas), making them unsuitable for environmentally friendly airbag manufacturing and disposal.

[0007] Patent Document 1 describes an airbag device having a protective cloth sewn along a seam, positioned away from the seam where opposing portions of a base fabric are sewn together, so as to cover the seam from the inside where gas from the inflator is introduced (see Figures 2 and 7 of the same document). Patent Document 1 discloses a protective material for the seam, but such a protective material is fixed to the base fabric by sewing, not by adhesive. The purpose of such a protective material is to prevent the seam from being directly exposed to and damaged by the high-pressure gas from the inflator, and to distribute tension to the seam of the protective material to prevent damage to the seam of the pair of base fabrics, and is not intended to maintain internal pressure in a state where the seam is not damaged.

[0008] Patent Document 2 discloses an airbag having a wall portion containing a laminate material, wherein the laminate material includes a backing layer having a breathable sheet-like structure made of a woven or knitted fabric, at least two co-extruded polymer films, a first polymer layer having a predetermined glass transition temperature on the side of the backing layer, and a second polymer layer having a predetermined storage modulus on the side opposite to the backing layer, and the wall portion is bonded so that the second polymer layer is bonded at the edge of the airbag, and a method for bonding the first polymer layer and the second polymer layer by applying different thermal energy to them. The object of the invention described in Patent Document 2 is to provide an airbag that can be produced at low cost, is easy to seal, and is highly reliable (see Fig. 1-3 in the same document). Patent Document 2 does not disclose any protective material for airbag sutures, and its manufacturing method is primarily aimed at increasing productivity, not at maintaining internal pressure.

[0009] Patent Document 3 below describes an airbag in which panels are joined at joints. Each panel has a woven fabric and a synthetic resin film adhered to the woven fabric via an adhesive. A hot-melt adhesive sheet is interposed between the panels, and the panels are joined by pressure heating. The synthetic resin film is disposed on the outside of the airbag. The object of the invention described in Patent Document 3 is to provide an airbag having high strength at the joint portion between panels, excellent durability, prevention of gas leakage, and good handling properties (see FIGS. 3 and 4). In the invention described in Patent Document 3, the strength of the joint portion between panels is increased by adhering the panels with a joint layer made of a hot-melt adhesive, the yarn density of the woven fabric is decreased, and the synthetic resin film is disposed outside the panel to avoid direct contact of the woven fabric with the inner surface of the vehicle body, thereby enhancing durability. Further, the hot-melt adhesive is impregnated into the sewing portion of the woven fabric to prevent gas leakage from the needle holes and yarn pulling out of the sewing. Patent Document 3 does not describe a method for preventing stress from being applied to the joint portion between panels when stress is applied to the outer peripheral adhesive surface of the airbag during airbag deployment, resulting in adhesive failure and gas leakage from the sewing holes. Moreover, there is no technical concept of adhering a protective material for sewing to the base fabric at a location separate from the sewing and maintaining the adhesion between the protective material and the base fabric to achieve internal pressure retention.

[0010] Thus, in view of the prior art level, an airbag having excellent internal pressure retention performance, low cost, high productivity, and excellent compactness during inflation and deployment, and a manufacturing method thereof have not yet been provided.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

[0012] Given the current state of prior art, the problem that the present invention aims to solve is to provide a highly productive method for manufacturing an airbag in which a pair of base fabric panels are sewn together at their outer edges to form a bag, wherein the outer surfaces of both ends of a folded, non-breathable protective material are bonded to the inner surface of each of the pair of base fabric panels in an adhesive region of a predetermined width along the seam, having a proximal end and a distal end extending from the vicinity of the seam towards the inside of the bag, thereby forming an airtight structure and maintaining this even when deployed, thereby improving internal pressure retention performance, while also providing a low-cost, highly productive, and compact airbag manufacturing method. [Means for solving the problem]

[0013] The inventors of this invention, after diligently studying and conducting numerous experiments in order to solve the aforementioned problems, unexpectedly discovered that the problems could be solved by using a non-permeable protective material having the structure defined below, and thus completed the present invention. In other words, the present invention is as follows:

[0014] [1] A method for manufacturing an airbag comprising at least one pair of base fabric panels sewn together at their outer edges, comprising the following steps: A welding process is performed in which a folded strip-shaped non-breathable film-like protective material, consisting of a single-layer resin film with a release liner sandwiched between the inner surfaces of a pair of base fabric panels, or a laminated resin film consisting of two or more layers including a first surface layer and a second surface layer, is sandwiched between the inner surfaces of each of the pair of base fabric panels while tension is applied, and heat or ultrasonic waves are applied from the outside of the pair of base fabric panels to weld the surface of the single-layer resin film or the first surface layer to the inner surface of the base fabric panel in an adhesive area of ​​a predetermined width; in this process, the surfaces of the single-layer resin film on the release liner side are not welded together due to the presence of the release liner, or the second surface layers of the laminated resin film are not welded together by heat welding or ultrasonic welding, or are welded together by heat welding or ultrasonic welding, but when tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the second surface layer peels off; The aforementioned melt Before wearing, melt A suturing step, performed after or simultaneously with the application, in the vicinity of the adhesive area, to sew the pair of base fabric panels together; The manufacturing method, including the above. [2] The method according to [1], wherein the folded strip-shaped non-breathable film-like protective material is fed out from a roll in which it has been wound in a folded state and sandwiched between a pair of base fabric panels. [3] A step of heating a part or all of the folded strip-shaped non-breathable film-like protective material before the welding step of welding the folded strip-shaped non-breathable film-like protective material; The method described in [1] or [2] above, including the method described in [1] or [2] above. [4] A step of cooling part or all of the folded strip-shaped non-breathable film-like protective material after a welding step in which the folded strip-shaped non-breathable film-like protective material is welded together; The method according to any one of the above [1] to [3], including the above. [5] A welding step in which the folded strip-shaped non-breathable film-like protective material is welded, wherein the pressing pressure of the hot plate and / or cooling plate is intermittently applied and released while heating and / or cooling a part or the whole of the folded strip-shaped non-breathable film-like protective material; The method described in any of the above [1] to [4], including the above. [6] The method according to any one of [1] to [5], wherein the melting point of the resin constituting the first surface layer of the folded non-permeable film-like protective material, a laminated resin film, is 50°C to 160°C lower than the melting point of the resin constituting the second surface layer. [7] In the multilayer film comprising a first surface layer and a second surface layer of a single-layer or laminated resin film, which is the folded non-breathable film-like protective material, the difference in SP values ​​between any adjacent layers is 2.0 [cal / cm²] 3 ) 1 / 2 The method according to any of the above [1] to [6], wherein the method is greater than or equal to [1]. [8] In the multilayer film comprising a first surface layer and a second surface layer of a single-layer or laminated resin film, which is the folded non-breathable film-like protective material, the difference in HSP values ​​between any adjacent layers is 1.0 [cal / cm²]. 3 ) 1 / 2 The method according to any of the above [1] to [7], wherein the method is greater than or equal to [1]. [9] The method according to any one of [1] to [8], wherein, when a tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the length between the distal ends along the folded non-breathable film-like protective material is greater than or equal to the length between the distal ends along the pair of base fabric panels.

[10] The above melt A sewing step is performed after attachment, in which the pair of base fabric panels are sewn together near the adhesive area; The method of any one of the above [1] to [9], including the following:

[11] A method for manufacturing an airbag comprising at least one pair of base fabric panels sewn together at their outer edges, comprising the following steps: A welding process in which, while applying tension to a folded strip-shaped non-breathable film-like protective material consisting of two or more laminated resin films of a predetermined width, including a first surface layer and a second surface layer, is applied continuously from the underside of the base fabric panel, along the straight or curved outer edge of the base fabric panel, to weld the first surface layer to the upper surface of the base fabric panel; A welding process in which another base fabric panel is placed on top of the welded film-like protective material, and heat or ultrasonic waves are applied from the upper side of the overlapping base fabric panel to weld the first surface layer to the lower surface of the overlapping base fabric panel, wherein the second surface layers of the laminated resin film are not welded together by heat welding or ultrasonic welding, or are welded together by heat welding or ultrasonic welding, but when tensile force is applied to the base fabric panels during the deployment of the airbag, the second surface layer peels off; The aforementioned melt A sewing step is performed in which the base fabric panel is sewn together near the area of ​​welded joint after welding; The manufacturing method, including the above. [Effects of the Invention]

[0015] The method for manufacturing an airbag according to the present invention involves bonding the outer surfaces of both ends of a folded, non-breathable protective material to the inner surface of each of at least one pair of base fabric panels in an adhesive region of a predetermined width along the seam, with a proximal end and a distal end extending from near the seam towards the inside of the bag. When tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the adhesive region is substantially unaffected by the tensile force, thus maintaining an airtight structure. As a result, this method provides high internal pressure retention performance, low cost, high productivity, and excellent compactness, making it a highly productive method for manufacturing airbags. Therefore, the airbag and its manufacturing method according to the invention are suitably applicable to automotive airbags, particularly CABs and pedestrian airbags where internal pressure retention performance is especially required. [Brief explanation of the drawing]

[0016] [Figure 1] This is a plan view of an airbag in which a pair of base fabric panels, manufactured by the manufacturing method of this embodiment, are sewn together at their outer edges to form a bag. [Figure 2] This diagram illustrates the state of the airbag when it is sutured to the adhesive joint using silicone adhesive, at the location corresponding to cross-section AA in Figure 1. [Figure 3] This diagram illustrates the state of the non-breathable protective material in an airbag manufactured by the manufacturing method of this embodiment when the airbag is deployed. [Figure 4] This diagram illustrates a state in which, in an airbag manufactured by the manufacturing method of this embodiment, when a tensile force is applied between a pair of base fabric panels during the deployment of the airbag, the length between the distal ends along the folded non-permeable protective material is greater than or equal to the length between the distal ends along the pair of base fabric panels, thereby maintaining an airtight structure in the adhesive region. [Figure 5] This diagram illustrates a state in which a folded, non-breathable film-like protective material is a laminated resin film consisting of two or more layers, including a first surface layer and a second surface layer, and the first surface layer is welded to the base fabric panel, but the airtight structure in the bonded area is maintained because the second surface layers are not bonded to each other. [Figure 6] This diagram illustrates a state in which a folded, non-breathable film-like protective material is a laminated resin film of two or more layers, including a first surface layer and a second surface layer, and the first surface layer is welded to the base fabric panel, while the second surface layers are bonded together. However, when tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the second surface layers peel off, thereby maintaining an airtight structure in the bonded area. [Figure 7] This diagram illustrates the relationship between the resin constituting the first surface layer and the resin constituting the second surface layer of a laminated resin film, which is a non-breathable film-like protective material that is folded in half. [Figure 8] This is an explanatory diagram of an example of a manufacturing method for a folded, non-breathable film-like protective material (winding up a folded film). [Figure 9] This is an explanatory diagram showing the process of supplying a rolled-up, folded, non-breathable film-like protective material to the heat-sealing area. [Figure 10]This diagram illustrates the supply state of a folded film in a welding process in which a half-folded, strip-shaped, non-breathable film-like protective material, consisting of a single-layer resin film with a release liner of a predetermined width sandwiched between the inner surfaces of a pair of base fabric panels, or a laminated resin film consisting of two or more layers including a first surface layer and a second surface layer, is continuously sandwiched along the straight or curved outer edges of the pair of base fabric panels while tension is applied, and heat or ultrasonic waves are applied from the outside of the pair of base fabric panels to weld the surface of the single-layer resin film or the first surface layer to the inner surface of the base fabric panels. [Figure 11] This is an explanatory diagram of a method for winding a multilayer film, in a double-layered state, onto a 3-inch paper core using the inflation method with a multilayer circular die. [Figure 12] This is a schematic diagram of a jig (half-fold former) used for folding film in half. [Figure 13] This is an explanatory diagram of an example of an airbag (cushion) that includes an isolated seam in the center of a closed space. [Figure 14] This is an explanatory diagram of one method for adhering a folded film to an isolated seam in a closed space. [Figure 15] Figure 14 is an explanatory diagram of the sealing state by method 1. [Figure 16] This diagram illustrates another method of adhering a folded film to an isolated seam in a closed space, and the resulting sealing state. [Figure 17] This diagram illustrates the relationship between the layer structure of a folded film based on the difference in melting point (left) and the difference in interlayer SP value (right). [Modes for carrying out the invention]

[0017] Embodiments of the present invention will be described in detail below with reference to the drawings. Embodiments of the present invention relate to a method for manufacturing an airbag comprising at least one pair of base fabric panels sewn together at their outer edges, comprising the following steps: A welding process is performed in which a folded strip-shaped non-breathable film-like protective material, consisting of a single-layer resin film with a release liner sandwiched between the inner surfaces of a pair of base fabric panels, or a laminated resin film consisting of two or more layers including a first surface layer and a second surface layer, is sandwiched between the inner surfaces of each of the pair of base fabric panels while tension is applied, and heat or ultrasonic waves are applied from the outside of the pair of base fabric panels to weld the surface of the single-layer resin film or the first surface layer to the inner surface of the base fabric panel in an adhesive area of ​​a predetermined width; in this process, the surfaces of the single-layer resin film on the release liner side are not welded together due to the presence of the release liner, or the second surface layers of the laminated resin film are not welded together by heat welding or ultrasonic welding, or are welded together by heat welding or ultrasonic welding, but when tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the second surface layer peels off; A suturing step of sewing the pair of base fabric panels together near the bonded area before, after, or simultaneously with the aforementioned bonding; The manufacturing method includes the above.

[0018] [Base fabric panel (panel fabric, main panel)] There are no particular restrictions on the pair of base fabric panels; they can be plain weave fabrics of polyamide or polyester, which are commonly used as base fabrics for airbags. The fineness of the fibers constituting the base fabric used in this embodiment is preferably 150 to 900 dtex. A fineness of 150 dtex or more provides the strength required for an airbag, while a fineness of 900 dtex or less provides flexibility when used as a base fabric for an airbag. In this embodiment, it is preferable to use multifilaments for the fibers constituting the base fabric, and the single-fiber fineness is preferably 0.1 to 10 dtex. Within this range, a flexible airbag base fabric with a high deployment speed can be obtained. Furthermore, the weave density of the base fabric used in this embodiment is preferably 30 to 90 threads / inch in both the warp and weft directions, and the cover factor is preferably 1500 to 2500. Within this range, the base fabric for airbags is flexible and strong enough to withstand deployment. However, the cover factor is a value calculated by the following formula. CF = (Number of warp threads per 2.54 cm) × √(Total warp fineness (dtex)) + (Number of weft threads per 2.54 cm) × √(Total weft fineness (dtex))

[0019] The base fabric panel may be coated with resin on one or both sides, or laminated with a single-layer or multi-layer film, in order to reduce breathability. In this case, the resin used for the resin coating can be a silicone-based or polyurethane-based coating, or a thermal lamination method using a flame-retardant thermoplastic resin film. When coating with resin, the coating amount should be 5-50 g / m². 2 This is preferable. When laminating a film onto a base fabric, the thickness of the film is preferably 0.001 mm or more and 0.5 mm or less. Within this range, a base fabric that is flexible and has excellent airtightness can be obtained when used as a base fabric for airbags.

[0020] As illustrated in Figure 1, the airbag according to this embodiment may be formed by sewing together a pair of base fabric panels at their outer edges to create a bag. In Figure 1, reference numeral 2 indicates the seam (sewing) portion of the main panel, and reference numeral 4' indicates the position of the inner edge (top of the loop) of the half-folded non-breathable protective material, described below, located on the back side of the front base fabric panel. As shown in Figure 1, an inner tube (reference numeral 23), usually made in a cylindrical shape from a base panel of the same material, can be inserted into the opening, and when the airbag inflates and deploys, gas is instantaneously injected into the airbag from inside the inner tube.

[0021] [suture] The sutures are not particularly limited as long as they do not break when the airbag inflates and deploys, but preferably, they are machine-stitched with multifilament fiber sutures made of the same material as the base fabric panel. As mentioned above, in order to maintain internal pressure, it is required that no breakage occurs at the sutures when the airbag deploys and that there is substantially no gas leakage. The sewing thread may be a single strand of unplyed yarn, or a double-ply yarn made by twisting two or more strands of unplyed yarn together, and the total fineness of the resulting twisted fibers is preferably 700 to 2000 dtex. Furthermore, various suturing methods such as lockstitch and chain stitch can be used. A stitch count (stitch pitch) of 30 to 60 stitches per 10 cm is preferable.

[0022] [Half-folded, non-breathable film-like protective material] Figure 2 shows an enlarged view of the area corresponding to cross-section AA in Figure 1, illustrating the state of the airbag when sutured to a joint using silicone adhesive in the conventional technology, in order to prevent gas leakage at the suture. When using silicone adhesive, the silicone adhesive deforms and stretches during deployment, sealing the gas and improving internal pressure retention. However, the thickness of the silicone adhesive after curing increases the thickness of the airbag after folding (when stored), worsening its storage capacity. Furthermore, the long curing time of half a day to about a day reduces the productivity of the airbag.

[0023] The manufacturing method of this embodiment allows for the production of airbags with high productivity, in which, instead of using a silicone adhesive, the outer surfaces of both ends of a folded strip-shaped film-like non-breathable protective material are bonded to the inner surface of each of a pair of base fabric panels in a predetermined width bonding area along the suture, with a proximal end and a distal end extending from the vicinity of the suture towards the inside of the bag, with the ends of the material being either straight or curved, and the folded non-breathable film-like protective material is a laminated resin film of two or more layers including a first surface layer and a second surface layer, and the first surface layer is welded to the base fabric panel, but the second surface layers are either not bonded to each other, or they are bonded but the second surface layers peel off when tensile force is applied to the pair of base fabric panels during the deployment of the airbag. When an airbag is deployed, if tensile force is applied between a pair of base fabric panels, it is preferable that the length between the distal ends along the folded non-breathable film-like protective material is greater than or equal to the length between the distal ends along the pair of base fabric panels.

[0024] The manufacturing method of this embodiment can be used for the entire outer periphery of the airbag or for a portion of the airbag. Here, "a portion" means, for example, 50% or more. When using the manufacturing method for a portion of the airbag, in order to obtain airtightness for the entire airbag, a method can be selected in which silicone adhesive is used in the seams of other parts of the airbag that may cause gas leaks. Furthermore, a structure with these characteristics can be applied near the seams of any two (a pair) of base fabric panels in an airbag composed of at least two or more base fabric panels. The pair of base fabric panels do not necessarily have to be the same shape; as long as the airtightness of the adhesive area is not impaired, the sewing lines between the pair of base fabric panels may have different shapes in a three-dimensional stitching.

[0025] In this specification, the term "airbag comprising at least one pair of base fabric panels sewn together at their outer edges" refers to an airbag in which base fabric panels are sewn together to form an inflatable chamber, and in which two or more base fabric panels are sewn together at the outer edge of the chamber. Therefore, it is not limited to an airbag composed only of two base fabric panels made by overlapping two base fabric panels of the same shape, as shown in Figures 1 and 13, and is not limited to the number of base fabric panels constituting the airbag or the overall structure of the airbag, as long as it has a portion where two or more base fabric panels are joined together at the outer edge of the chamber. Here, the base fabric panels to be sewn together are at least one pair, that is, at least two panels, and these sewn base fabric panels may be made of the same fabric or different fabrics. For example, this broadly includes a single symmetrical base fabric panel folded along a line of symmetry and the overlapping parts sewn together, a single strip-shaped base fabric panel rolled into a tube and the overlapping parts sewn together, and a structure in which three or more base fabric panels are sewn together, that is, as long as it has a partial structure in which the sewn parts of the base fabric panels are covered with a non-breathable protective material.

[0026] In this specification, the term "non-permeable" refers to the surface properties of a protective material that suppress airflow to an extent that does not significantly impair the airtightness of the airbag. When a differential pressure of 500 Pa is applied to the front and back of the protective material, the amount of gas passing through the surface is 0.5 L / dm³. 2 It is preferably less than or equal to / min, and 0.1 L / dm 2 Less than / min is more preferable, and 0.05 L / dm 2 A value of / min or less is even more preferable.

[0027] Figure 3 illustrates the state of the half-folded non-breathable protective material when the airbag is deployed. As can be seen from Figure 3, the half-folded non-breathable protective material takes on a loop shape toward the inside of the airbag, forming an airtight structure in the area where it is bonded to the base fabric panel, thus providing internal pressure retention. In the airbag manufactured by the manufacturing method of this embodiment, preferably, when the airbag is deployed, the length between the distal ends along the folded non-breathable protective material is greater than or equal to the length between the distal ends along a pair of base fabric panels, thereby maintaining an airtight structure in the adhesive region. That is, as shown in Figures 4(a) and (b), because the loop-shaped protective material has sufficient length, when the airbag is pulled horizontally from the seam during deployment, substantially no force is applied to the adhesive region between the protective material and the base fabric panel, and there is no peeling or breakage in the adhesive region, thus maintaining airtightness. Furthermore, if the non-breathable film-like protective material has high extensibility, even if the length of the loop of the protective material before airbag deployment (when the airbag is contained) is approximately the same as or shorter than the adhesive distance along the base fabric panel, the non-breathable protective material is stretched by the tensile force applied during airbag deployment, and if the seam breaks first, substantially no force is applied to the adhesive region, resulting in a similar outcome. The state when the airbag deploys can be simulated and confirmed, for example, by using the following method. First, remove the contained airbag, cut a portion of the protective material and base fabric panel, spread a pair of base fabric panels 180° as shown in the deployed state in Figures 4(a) and (b), and when each base fabric panel is grasped and pulled in a direction parallel to the base fabric panel, check whether the suture breaks before the protective material. At this time, care should be taken to position the suture so that it is approximately perpendicular to the direction of tension. As mentioned above, Figure 4(a) is the first pattern, and Figure 4(b) is the second pattern (loop outside, film folded and stored), and in either pattern, when the airbag deploys, the length between the distal ends along the folded non-breathable protective material is greater than or equal to the length between the distal ends along the pair of base fabric panels, thereby maintaining an airtight structure in the adhesive area.

[0028] In this specification, the term "half-folded non-breathable film-like protective material" includes not only materials that are folded in half when an airbag is housed, as shown in the upper part of Figures 4(a) and (b), that is, a single strip-shaped single-layer or multi-layer resin film or laminate base fabric folded in half, but also materials that are folded multiple times, such as in an accordion shape, or materials made by overlapping two strip-shaped (including curved) single-layer or multi-layer resin films or laminate base fabrics and bonding or welding one end together with adhesive (i.e., made by a two-layer bonding method). However, from the viewpoint of improving productivity, it is preferable to manufacture the protective material by continuously supplying half-folded strip-shaped films, etc., and heat-welding them, as shown in Figures 8-10 and 12, rather than by a two-layer bonding method.

[0029] This strip-shaped, half-folded, non-breathable film-like protective material is adhered to the base fabric in a straight or curved manner along the seam. In the manufacturing method of this embodiment, a strip-shaped, half-folded, non-breathable film-like protective material can be made by using two pieces of resin film cut into a desired shape, and welding the outer layers of one end (inner edge side) of a multilayer film together (for example, in the case of a PE (second surface layer) - PA6 / 12 (first surface layer) multilayer film, peeling off a part of the second surface layer and joining the first surface layers together) along the inner edge so that the length from the outer edge is a predetermined length, for example, with a width of 5 mm, or by bonding them together with a cyanoacrylate-based instant adhesive (manufactured by Konishi Co., Ltd.), and allowing it to dry thoroughly (i.e., instead of a strip shape, by bonding two pieces of protective material cut into a base fabric panel shape (horseshoe shape) as shown in Figure 1), but it is preferable to manufacture the protective material by continuously supplying a strip-shaped piece of resin film that has been folded in half, as shown in Figures 8 to 10, and heat welding it while applying tension, rather than manufacturing it by bonding two pieces together. This is because, while the two-piece lamination method requires cutting the resin film along the sewing shape of the airbag, using a half-folded strip of resin film maximizes the efficiency of film utilization and increases productivity because there is no process of bonding the films together. Furthermore, since actual airbags deploy instantly from a folded state, a portion of the airbag may be exposed to a very high inflator gas flow rate during the initial stages of deployment. However, by using a single piece of resin film, the need for bonding between resin films is eliminated, preventing the bonded portion from being exposed to the gas flow rate and being damaged. Moreover, because there is no need to bond the resin films together, there is less change in the thickness and hardness of the loop-shaped resin film between the distal ends along the half-folded strip of resin film. Even when exposed to a high gas flow rate during airbag deployment, stress concentration at the bonding interface between the resin films and other points of change in thickness and hardness is prevented, thus preventing the loop-shaped structure from being damaged.In addition, by using a single sheet of resin film, it is possible to prevent the film from becoming stiff due to adhesion between the films, compared to the method of laminating two sheets together. Furthermore, by eliminating the need for adhesive between the films, the airbag can be made lighter and its storage capacity can be improved.

[0030] By using a resin film as a half-folded non-breathable protective material, and employing the manufacturing method described later, which involves continuously supplying the material and applying tension while heat-welding, even a single sheet of non-breathable protective material can be welded without wrinkles, including curved sections (including R sections and reverse R sections), resulting in an airbag with excellent airtightness.

[0031] As for the non-breathable film-like protective material, there are no particular restrictions as long as it is not damaged when the airbag inflates and deploys, and single-layer or multi-layer resin films can be used. From the viewpoint of reducing the weight and compactness (foldability, storage) of the airbag, it is preferable to use a single-layer or multi-layer resin film as the non-breathable protective material. When using a single-layer or multi-layer resin film as the non-breathable film-like protective material, the adhesive strength can be increased and the internal pressure retention of the airbag can be improved by bonding it to a base fabric panel laminated with the same type of single-layer or multi-layer resin film. Furthermore, by using the same type of single-layer or multi-layer resin film (and substrate) for the non-breathable protective material and the base fabric panel, recyclability can be improved.

[0032] In this specification, the term "adhesion" includes bonding with adhesives and welding by ultrasound or heat. As described in the section on the method of manufacturing an airbag below, if the material of the base fabric panel and the material of the outer layer of the half-folded non-breathable protective material are of the same type, the base fabric panel and the protective material can be bonded by welding using heat or ultrasound to form an adhesive area that will not peel off even when the airbag is deployed and will maintain airtightness. Welding without the use of adhesives is preferred from the viewpoint of thickness after folding, productivity, and recycling.

[0033] As shown in Figures 4(a) and 4(b), the term "adhesion region (5, 5')" has a proximal end (6, 6') and a distal end (7, 7') relative to the suture (2). As shown in Figure 4(a), the proximal end (6, 6') may be located inside the airbag from the suture (2) or outside the airbag. In the latter case, the adhesion region will extend to the seam allowance. Furthermore, as shown in Figure 4(b), the loop structure of the non-breathable protective material folded in half in the adhesive area may be positioned so that it faces the outer edge of the airbag (outside the airbag). This is because, in the airbag deployed state, the folded non-breathable protective material takes on a loop shape toward the inside of the airbag, and the length between the distal ends along the folded non-breathable protective material is greater than the length between the distal ends along the pair of base fabric panels, allowing an airtight structure to be formed in the adhesive area with the base fabric panels, similar to the case in Figure 4(a). However, when sewing the outer edge of the airbag after bonding the protective material, it is preferable to position the loop structure of the non-breathable protective material so that it faces the inside of the airbag in order to avoid damaging the part of the protective material that contributes to maintaining internal pressure with the sewing. The "adhesive area" only needs to be bonded in such a way that it does not break or peel off when the airbag inflates and deploys, and maintains airtightness and internal pressure retention.

[0034] In the airbags manufactured by the manufacturing method of this embodiment, the thickness of the non-breathable film-like protective material is preferably 0.001 mm to 0.5 mm, and more preferably 0.001 mm to 0.1 mm, from the viewpoint of folding thickness.

[0035] In the airbags manufactured by the manufacturing method of this embodiment, the adhesive strength (peel strength) in the adhesive region between the base fabric panel and the non-breathable film-like protective material is preferably 1 N / cm or more, and more preferably 3 N / cm or more, from the viewpoint of airtightness. If the adhesive strength is 3 N / cm or more, the occurrence of leaks caused by the film peeling off from the panel base fabric due to the air pressure of the gas when the airbag deploys is greatly reduced.

[0036] The tensile modulus of the folded strip-shaped non-breathable protective material is preferably 100 to 800 MPa in both the MD (mechanical direction) and TD (transverse direction), more preferably 150 to 600 MPa, and even more preferably 200 to 500 MPa. However, the tensile modulus of the film referred to here is the measurement result when the strip-shaped non-breathable film-like protective material is unfolded from its folded state and pulled. When the strip-shaped non-breathable film-like protective material is deformed to conform to a curved outer edge by applying tension, having the above-mentioned tensile modulus (flexibility) makes it easy to form a curved structure that conforms to the curved parts (including R parts and reverse R parts) that are normally used in the main fabric of airbags. By setting the tensile modulus to 100 to 800 MPa, the appropriate flexibility results in a film with good handling properties (a balance between ease of deformation in curved parts and handling of the film). Furthermore, regarding the durability required for the film, the tensile breaking strength of the film is preferably 10 to 100 MPa for both MD and TD, more preferably 15 to 80 MPa, and even more preferably 20 to 60 MPa, from the viewpoint of durability. By setting the tensile breaking strength to 100 MPa or less, the rigidity is reduced, resulting in a film with good handling properties. Moreover, when deforming a strip-shaped non-permeable, breathable film-like protective material to follow a curved outer edge by applying tension, it is preferable to use a thermoplastic resin film because the film can be easily stretched by applying heat.

[0037] In this embodiment, the airbag may have, in the adhesive region, an R-shaped section with a radius of curvature of 300 mm or less, and / or an inverted R-shaped section with a radius of curvature of 300 mm or less, as shown in Figures 1 and 13. Here, the R section refers to the part of the stitching line along the outer edge of the base fabric panel that has a curved shape that is convex on the side opposite to the airbag inflation chamber. For example, this corresponds to area X in Figure 1. On the other hand, the reverse R section refers to the part of the stitching line along the outer edge of the base fabric panel that has a curved shape that is convex on the side opposite to the airbag inflation chamber. For example, this corresponds to area Y in Figure 1. In curved stitching sections including such R sections and reverse R sections, wrinkles are more likely to occur when bonding the non-breathable protective material along the stitching line compared to straight stitching sections, and tension is more likely to be applied to the stitching section when the airbag is deployed. The degree of wrinkle formation when bonding the non-breathable protective material can be confirmed by measuring the difference in height (peak-valley difference) between the wrinkled part and the normal part. The difference in height (peak-valley difference) between the wrinkled part and the normal part of such R sections is preferably 400 μm or less, more preferably 300 μm or less, even more preferably 200 μm or less, and most preferably 100 μm or less. By keeping the surface step difference (peak-valley difference) of the R section to 400 μm or less, the difference in height between the wrinkled and normal sections can be reduced, preventing stress concentration, suppressing gas leakage from the adhesive joint, and resulting in an airbag with excellent storage capabilities. Furthermore, the ratio (R portion / straight portion) of the difference in height (peak-valley difference) between the wrinkled portion of the R portion and the normal portion, and the ratio of the difference in height (peak-valley difference) between the wrinkled portion of the substantially straight portion excluding the R portion, is preferably 0.6 to 2.0, and more preferably 0.8 to 1.5.

[0038] Furthermore, the step height of the wrinkles was measured using a surface roughness measuring instrument (SURFTEST EXTREME SV-3000CNC) manufactured by Mitutoyo Corporation. The wrinkled area and the surrounding normal area were measured in three-dimensional mode according to the following measurement conditions. Using the arbitrary cross-section extraction function in the obtained three-dimensional image, a cross-section was extracted that included the largest step height. A baseline was drawn connecting the start and end points of the wrinkled area (step height) in the extracted cross-section (2D), and the maximum height from this baseline was determined. (Surface roughness measurement conditions) • Measurement length: 10mm ·Measurement width: 5mm ·Measurement speed: 5mm / sec • Sampling pitch: 1 μm • Sampling interval: 50 μm · Stylus: radius = 10 μm (Code No. 12AAB415) (Image processing) · Implement trend correction only for "plane"

[0039] As shown in FIGS. 5 to 7, when a single-layer resin film is used as the protective material during the heat welding of the base fabric panel and the protective material by heating, if a release paper is inserted inside the loop, it is possible to adhere a protective material with a sufficient loop length that can maintain the airtightness of the adhesion area. There is no particular limitation on the material of the release paper, and paper, cloth, film, etc. can be used as long as it can prevent the adhesion of single-layer resin films to each other. Compared with the above configuration, when using a multilayer resin film as the semi-folded strip-shaped protective material, without using a release paper, and the second surface layers inside the loop are either not adhered or are adhered by heat welding or ultrasonic welding, but when tensile strength is applied to the pair of base fabric panels during the deployment of the airbag, it is more advantageous to configure the second surface layer to peel off. This is because the steps of inserting and / or removing the release paper are unnecessary, the consideration of the material and physical properties of the release paper and its handling are unnecessary, and the adjustment of tension is facilitated, thus improving the productivity of the airbag. Also, with such a configuration, even when it is difficult to take out the release paper for sewing in a curved or circular shape due to the sewing shape of the airbag, the release paper does not remain in the airbag, so it does not cause an increase in the weight of the airbag or deterioration of the storage property, and it is possible to avoid the release paper affecting the deployment speed and deployment behavior of the airbag.

[0040] Such a configuration is, for example, such that the melting point of the resin constituting the first surface layer of the laminated resin film, which is a semi-folded airtight film-shaped protective material, is 50°C to 160°C, preferably 60°C to 160°C lower than the melting point of the resin constituting the second surface layer, so that the second surface layers inside the loop are not welded to each other, or the difference in the SP values of the resin constituting the first surface layer, the resin constituting the second surface layer, and the resin constituting other layers of the laminated resin film, which is a semi-folded airtight film-shaped protective material, is 2.0 [cal / cm 3 )1 / 2 The above difference can be achieved by causing delamination between any of the layers, or by causing the second surface layer to peel off from an adjacent layer.

[0041] In other words, in a multilayer film including a first surface layer and a second surface layer of a laminated resin film which is a folded non-breathable film-like protective material, the difference in SP value between any adjacent layers is 2.0 [cal / cm²]. 3 ) 1 / 2 Preferably, it should be 2.5 [cal / cm³] or more. 3 ) 1 / 2 ] or more, and more preferably 3.0 [cal / cm²] 3 ) 1 / 2 ] or more, and more preferably 4.0 [cal / cm³] 3 ) 1 / 2 That's all.

[0042] The following explanation of this configuration will be given with reference to Figure 17. For example, the melting point of PA6 / 12 is 128°C, TPEE is 216°C, PA6 / 66 is 194°C, PA12 elastomer is 176°C, PO (acid-modified polyethylene) is 120°C, and PE (LDPE) is 110°C. Therefore, by using TPEE (second surface layer)-PA6 / 12 (first surface layer) multilayer film, TPEE-PO-PA6 / 12 multilayer film, or PA6 / 66-PO-PA6 / 12 multilayer film as protective materials, the difference between the melting point of the resin constituting the first surface layer and the melting point of the resin constituting the second surface layer can be made to 50°C or more. Here, a preferred range for the melting point difference is 50°C to 160°C, more preferably 60°C to 160°C, and even more preferably 80°C to 160°C. By setting the melting point difference to 50°C or higher, the range of bonding temperatures in which adhesion strength with the base fabric panel can be increased and fusion between the second surfaces can be made less likely can be widened, thereby improving production stability. Furthermore, by setting the melting point difference to 160°C or lower, for example, when producing a film by inflation molding, the flow unevenness and melt tension are properly maintained, thus improving the stability of film formation. Furthermore, the melting point of the resin constituting the protective material is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher. By setting the melting point to 90°C or higher, sufficient adhesive strength can be maintained even when the temperature inside the vehicle becomes high.

[0043] Also, for example, the SP value of PE is 8.1 [cal / cm³] 3 ) 1 / 2 ], the SP value of PA6 / 66 is 13.6 [cal / cm³] 3 ) 1 / 2 ], the SP value of PA6 / 12 is 13.6 [cal / cm³] 3 ) 1 / 2 ], the SP value of PET is 10.7 [cal / cm³] 3 ) 1 / 2 Therefore, if PE (second surface layer) - PA6 / 66 (release layer side of the first surface layer, which is a multilayer film) or PE (second surface layer, release layer) - PET (first surface layer) is used as a protective material, the difference from the SP value of the PA base fabric or PET base fabric will be 2.0 [cal / cm²]. 3 ) 1 / 2 It can be made to be more than ].

[0044] For example, in the right-hand diagram of Figure 17 (SP value difference), the first surface layer (base fabric panel side) is composed of an adhesive layer (PA6 / 12), while the second surface layer (inside the loop) is composed of a release layer (PE). It can be considered that the layer consists of four layers, including an intermediate layer (acid-modified PE) and a high-melting-point layer (PA6 / 66). Here, not only is there a difference in SP value between the high-melting-point layer (PA6 / 66) and the release layer (PE), but the difference in SP value between any adjacent layers of the adhesive layer (PA6 / 12), X layer (e.g., intermediate layer (acid-modified PE)), and high-melting-point layer (PA6 / 66) that make up the first surface layer is 2.0 [cal / cm²]. 3 ) 1 / 2 It should be noted that even if the level is above this, the aforementioned peeling effect will still be achieved.

[0045] The configuration based on the SP value difference described above is preferable to the configuration based on the melting point difference described above. This is because the fusion (processing) temperature can be raised above the melting point of the film, which can lead to stronger adhesion between the base fabric panel and the film, and can also improve productivity by increasing the processing speed.

[0046] Furthermore, the SP value (Hildebrand solubility parameter) is a physical property value defined as the square root of the cohesive energy density, and since it indicates the dissolution behavior of the solvent, the inventors of this application used combinations with large differences in SP values ​​as an indicator for selecting the release layer. In addition, the SP values ​​of various resins are listed, for example, in "Various Standards and Guide to Usage: Plastic Material Testing Methods, Comparisons, Evaluations, and Results" by the Industrial Technology Center, p. 32 (2nd edition, May 10, 2011), and "Practical Polymer Science for Engineers" by Kodansha, 89.8.1, is cited as a reference for the calculation method of SP values.

[0047] In addition to the aforementioned SP value, Hansen's solubility parameter (HSP) is also a commonly used parameter for SP values. Although HSP values ​​are also shown in the examples, the difference in HSP values ​​is 1.0 (cal / cm³). 3 ) 1 / 2 The aforementioned peeling effect is achieved by doing so. Here, HSP is a predicted value obtained by Winmostar (V9.3.0) from CrossAbility Co., Ltd., and is calculated using the dispersion term (δD), polarization term (δP), and hydrogen bonding term (δH) between certain substances. In the case of copolymer compositions, the HSP is calculated by calculating the HSP of each homopolymer and summing the values ​​obtained by multiplying them by the composition ratio (volume ratio).

[0048] Furthermore, in order to avoid tacking in high-temperature environments and to ensure internal pressure retention after aging, the glass transition temperature (Tg) of the second surface layer (inside the loop) is preferably 0°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher. On the other hand, from the viewpoint of flexibility, the upper limit of the glass transition temperature is 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower.

[0049] Using the manufacturing method described above, in an airbag in which a pair of base fabric panels are sewn together at their outer edges to form a bag, On the inner surface of each of the pair of base fabric panels, the outer surfaces of both ends of a folded, non-breathable film-like protective material are bonded in a straight or curved manner in an adhesive region of a predetermined width along the suture, having a proximal end and a distal end extending from the vicinity of the suture towards the inside of the bag, and the folded, non-breathable film-like protective material is a laminated resin film of two or more layers including a first surface layer and a second surface layer, and the first surface layer is welded to the base fabric panel, but the second surface layers are not bonded to each other, or are bonded but the second surface layers peel off when tensile force is applied to the pair of base fabric panels during the deployment of the airbag, thereby enabling the provision of an airbag with high productivity.

[0050] In the manufacturing method of this embodiment, for ease of welding the film into a curved shape (R-processability), the tensile modulus of the film is preferably 100 to 800 MPa in both the MD (machine direction) and TD (transverse direction), more preferably 150 to 600 MPa, and even more preferably 200 to 500 MPa. However, the tensile modulus of the film referred to here is the measurement result when a strip-shaped non-permeable, breathable film-like protective material is unfolded from a folded state and pulled. When the strip-shaped non-permeable, breathable film-like protective material is deformed to follow a curved outer edge by applying tension, having the above-mentioned tensile modulus (flexibility) makes it easier to form a curved structure that follows the curved part normally used in the main fabric of an airbag. By setting the tensile modulus to 100 to 800 MPa, the appropriate flexibility results in a film with good handling properties (balance between ease of deformation in curved parts and handling of the film). Furthermore, regarding the durability required for the film, the tensile breaking strength of the film is preferably 10 to 100 MPa for both MD and TD, more preferably 15 to 80 MPa, and even more preferably 20 to 60 MPa, from the viewpoint of durability. By setting the tensile breaking strength to 100 MPa or less, the rigidity is reduced, resulting in a film with good handling properties. Moreover, when deforming a strip-shaped non-permeable, breathable film-like protective material to follow a curved outer edge by applying tension, it is preferable to use a thermoplastic resin film because the film can be easily stretched by applying heat.

[0051] In the manufacturing method of this embodiment, methods for sandwiching a strip-shaped non-breathable film-like protective material along the straight or curved outer edge of a pair of base fabric panels include, as illustrated in Figures 8 to 10, preparing a roll from which a half-folded film has been wound and feeding the strip-shaped non-breathable film-like protective material from this wound roll to the welding location by heat welding or ultrasonic welding; preparing a roll from which the half-folded strip-shaped non-breathable film-like protective material has been wound in an unfolded state and feeding the strip-shaped non-breathable film-like protective material from this wound roll to the welding location by heat welding or ultrasonic welding after folding it in the process; and folding a strip-shaped non-breathable film-like protective material that has been pre-cut to the length of the straight or curved outer edge of a pair of base fabric panels in half and feeding it to the welding location by heat welding or ultrasonic welding. However, the first method is preferred. By winding a pre-folded film onto a roll, the pleats in the folded portion can be firmly secured. Furthermore, by continuously feeding the film from the roll, the folded portion of the film is less likely to shift, and the curling of the folded film is suppressed (because the film structure is symmetrical from top to bottom), which can lead to further benefits such as reduced wrinkle formation (improved quality).

[0052] In this manufacturing method, the method of applying tension to the aforementioned folded film (tape) is not particularly limited, but for example, as shown in Figure 17, a method can be used in which the tape is held down with one hand and the base fabric with the other hand, and the tension applied to the tape is adjusted to conform to the shape of the outer edge of the airbag. Alternatively, a roll of folded film may be prepared in advance, and a tension control mechanism may be provided in the process of feeding the strip-shaped non-breathable film protective material from the roll to the welding location by heat welding or ultrasonic welding.

[0053] Furthermore, as shown in Figure 10, for example, the base fabric can be sandwiched between upper and lower conveyor belts at the welding point, and heat can be applied while the base fabric is being transported by the conveyor belts and sandwiched between upper and lower heating plates, allowing for continuous welding. Near the welding point, the tape (sandwiched between the base fabric) is heated, and the tension applied causes the tape to stretch to conform to the shape of the outer edge of the airbag, enabling the non-permeable, breathable film-like protective material to be bonded without wrinkles, even to curved sections including R-shaped and reverse R-shaped sections. In addition, preheating part or all of the non-permeable, breathable film-like protective material using a heating plate or hot air before heat welding or ultrasonic welding makes it easier to stretch the tape to conform to the shape of the outer edge of the airbag. As shown in Figure 10, a cooling section using a cooling plate may be provided immediately after welding. Providing a cooling section improves the adhesion of the non-permeable, breathable film-like protective material. Furthermore, intermittently applying and releasing pressure on the hot plate and cooling plate can improve the welding workability of curved sections.

[0054] However, the method of bonding the aforementioned folded film (tape) by applying tension to it and continuously sandwiching it along the straight or curved outer edges of the pair of base fabric panels, while applying heat or ultrasonic waves from the outside of the pair of base fabric panels, can easily cause misalignment of the base fabrics because the upper and lower base fabrics are bonded continuously and simultaneously. In addition, the workability of inserting the tape by tucking it under the upper base fabric may be poor in the final stages of bonding or depending on the sewing shape of the airbag, where space may be limited.

[0055] Therefore, instead of the tension application and clamping method described above, a two-step method may be adopted in which, instead of sandwiching the tape between a pair of base fabric panels, the tape is adhered to one side of the first base fabric (Step 1), and then the second base fabric is placed on top of the tape and pressed down (Step 2).

[0056] [2Step method] A welding process in which, while applying tension to a folded strip-shaped non-breathable film-like protective material consisting of two or more laminated resin films of a predetermined width, including a first surface layer and a second surface layer, is applied continuously from the underside of the base fabric panel, along the straight or curved outer edge of the base fabric panel, to weld the first surface layer to the upper surface of the base fabric panel; A welding process in which another base fabric panel is placed on top of the welded film-like protective material, and heat or ultrasonic waves are applied from the upper side of the overlapping base fabric panel to weld the first surface layer to the lower surface of the overlapping base fabric panel, wherein the second surface layers of the laminated resin film are not welded together by heat welding or ultrasonic welding, or are welded together by heat welding or ultrasonic welding, but when tensile force is applied to the base fabric panels during the deployment of the airbag, the second surface layer peels off; A suturing step is performed in which the base fabric panel is sewn together near the area of ​​adhesion obtained; The manufacturing method, including the above.

[0057] In the 2-step method, instead of sandwiching the tape between a pair of base fabric panels, the tape is first fed onto one base fabric panel while tension is applied, and the tape is welded onto the first base fabric by heating from below, thereby fixing the tape onto one base fabric panel without wrinkles (step 1). Then, the second base fabric is placed on top of the tape and pressed together by heating by heat welding or ultrasonic welding (step 2). As a result, the simultaneous operation of the upper and lower base fabrics described above is unnecessary, and only one base fabric needs to be operated. Also, since the tape is not sandwiched between the base fabrics, the situation where the space becomes narrow at the final stage of bonding does not occur.

[0058] In this manufacturing method, the method of applying tension to the tape is not particularly limited. Similar to the tension application and clamping method described above, a method can be used in which the tape is held down with one hand and the base fabric with the other, and the tension applied to the tape is adjusted to conform to the shape of the outer edge of the airbag. Alternatively, a roll of half-folded film may be prepared in advance, and a tension control mechanism may be provided in the process of feeding the strip-shaped non-breathable film protective material from this roll to the welding location by heat welding or ultrasonic welding. This manufacturing method has the advantage that, since the tape is not sandwiched between the base fabrics, it is easy to perform the operation of continuously welding while automatically inserting the tape into the heating plate of the welding machine (belt heat press machine). By automatically inserting the tape into the heating section, the occurrence of processing defects due to misalignment of the tape caused by manual work is reduced. Furthermore, when automatically inserting tape into a belt heat press machine, tension can be indirectly applied to the tape by changing the direction when feeding the base fabric, causing the tape to stretch near the welding point to conform to the shape of the outer edge of the airbag. In this manufacturing method, similar to the tension application and clamping methods described above, part or all of the tape can be preheated, a cooling section can be provided, and the pressure of the heating plate and cooling plate can be intermittently applied / released. For example, when preheating the tape, the tape can be welded onto the first base fabric using a heating plate from below the belt heat press machine, while the tape can be assisted in stretching the R-shaped and reverse R-shaped sections by heating with an upper heating plate.

[0059] In this manufacturing method, the method for placing a second base fabric on top of the aforementioned tape and heating it by heat welding or ultrasonic welding is not particularly limited. It may be done continuously using a belt heat press machine as in the first step, or it may be done all at once using a heat press machine that can heat the welded parts simultaneously. However, from the viewpoint of productivity, it is preferable to use a heat press machine that can heat the welded parts simultaneously. In this manufacturing method, since the welded parts are heated twice, a secondary effect can be expected in that the processing speed can be improved by making the first step a temporary fix.

[0060] [Method for manufacturing an airbag including an isolated seam in a closed space] In order to ensure the retention of internal airbag pressure in an isolated sewn section of a closed space, as shown in Figure 13, using tension application and clamping methods, it is necessary to manufacture the folded strip of film so that neither the beginning nor the end ends are open. Therefore, the following two methods can be employed. One method, as shown in Figure 14, involves cutting a folded strip of film to a predetermined length with some leeway, and sealing both ends in advance (a) (for example, by peeling off the inner LDPE film and then heat-sealing it for a sufficient amount of time). Then, leaving one end intact, the film is sandwiched between the base fabric and bonding (heat welding) is started (b), and finally the other end is overlapped and the two ends are bonded together (c), after which it is sewn (d). The sealed state after sewing is shown in Figure 14. The second method, as shown in Figure 15, involves not pre-sealing both ends of a folded strip of film, but instead inserting end 1 into the base fabric, crossing the dotted line that will become the sewing area to the right (see left end of Figure 15), and starting the bonding (heat welding) process. Finally, the other end is overlapped, similarly crossing the dotted line that will become the sewing area to the right, bonding the two ends together, and then sewing. As shown in the right end of Figure 15, it can be seen that the airbag is sealed by the bonded area in both the A-A' section and the C-C' section. As illustrated in Figures 15 and 16, there may be areas where the folded strip-shaped non-breathable protective material is overlapped and bonded to the inner surface of each of the pair of base fabric panels, and where the ends of the non-breathable protective material are sealed. Here, "overlapping and bonded" of the non-breathable protective material means that multiple pieces of the non-breathable protective material are placed on top of each other, the non-breathable protective material closest to each of the pair of base fabric panels is bonded to each other. For example, as shown in Figures 15 and 16, the non-breathable protective material can be overlapped and bonded to the same sewing area, or, in a sewing shape with a branching point, a folded strip-shaped non-breathable protective material placed near one sewing line and a folded strip-shaped non-breathable protective material placed near the other sewing line can be partially overlapped and bonded near the sewing branching point. In either case, the multiple non-breathable protective materials form a loop-like structure bonded together to the inner surface of each of the base fabric panels, and when tensile force is applied between the pair of base fabric panels, the length between the distal ends along the folded non-breathable protective material can be greater than or equal to the length between the distal ends along the pair of base fabric panels. "The end portions of the non-breathable protective material are sealed" means that the end portions of the multiple non-breathable protective materials are not open to the inflation chamber of the airbag. Here, the method of sealing the end portions of the non-breathable protective material is not particularly limited and may be bonded with adhesive, heat-welded, ultrasonically welded, or folded. In addition, as shown in Figure 16, a structure can be adopted in which the end portions are exposed to the outside of the inflation chamber. This manufacturing method can be used when welding a folded, non-breathable protective material to the vicinity of a sewn shape with branching points or a bent sewn shape, or when the airbag size is large and the process needs to be divided for ease of handling, etc., as a way to intentionally create a joint section of a folded, non-breathable protective material. Furthermore, it can be widely applied to methods such as a two-step method or a two-piece bonding method, regardless of whether tension is applied or the clamping method is used. [Examples]

[0061] The present invention will be specifically described below with reference to examples and comparative examples. First, we will explain the materials used in the examples and comparative examples, the methods for measuring their physical properties, etc.

[0062] [(Si) coated (base) fabric] As the Si-coated fabric used for the base fabric panel and / or protective material, a plain weave fabric woven using nylon 66 multifilament fibers for both warp and weft was used, with silicone resin coated on one side. The total fineness of the yarns constituting the base fabric was 470 dtex, the number of filaments was 136, the weave density of the coated fabric was 49 threads / inch (2.54 cm), and the amount of silicone resin coating was 25 g / m 2 That was the case.

[0063] (Film production method) The protective film was prepared as follows. As illustrated in Figure 11, a multilayer circular die was used to wind a desired multilayer film in a double-layered state onto a 3-inch paper tube by the inflation method. At this time, the inner surface 3b of the tubular film became the adhesive layer and the outer surface 3a became the outer layer during film formation. The film formation conditions were as follows. Die temperature setting: 210℃ Circular Dye: Lip outer diameter = 95mm, Lip clearance = 3mm Blow-up ratio: 1.1 times Air ring temperature: 22℃ Film surface temperature immediately before pinch roll: 32℃ Distance between circular die and pinch roll: 2.4m Pickup speed: 12m / min

[0064] (Raw materials for film) (Resin A) PE:LDPE (manufactured by Asahi Kasei): Product name "Suntech LD F1920" (MFR=2.0, Tm=110℃, SP value=8.1 (cal / cm) 3 ) 1 / 2 HSP value = 18.0 (cal / cm³) 3 )1 / 2 ) (Resin B) PA6 / 12: Product name "Ube Nylon 7128B" (manufactured by Ube Industries) Mido 6 / 12 copolymer (Tg=47℃, Tm=128℃, SP value=13.6 (cal / cm) 3 ) 1 / 2 HSP value = 20.7 (cal / cm³) 3 ) 1 / 2 ) (Resin C) PA6 / 66: Product name "Ube Nylon NAV503X10" (manufactured by Ube Industries, Ltd.) Polyamide 6 / 66 copolymer (Tg=43℃, Tm=194℃, SP value=13.6 (cal / cm²) 3 ) 1 / 2 HSP value = 22.8 (cal / cm³) 3 ) 1 / 2 ) (Resin D) m-PE: Product name "Admer NF528" (manufactured by Mitsui Chemicals) Acid-modified polyethylene (Tm=120℃) (Resin E) PO Elastomer: Product name "Engage EG8100" (Dow Chemical, Made in Japan) (Tm=60℃, Melt Index=1.0g / 10min (190℃ / 2.16kg))

[0065] The film configurations used in Examples 1 to 8 are shown in Table 1 below.

[0066] (Tensile elongation of film at break) The tensile elongation at break of the film was measured in accordance with ASTM D-882. The measurements were performed in an atmosphere of 23°C and 50% RH. The tensile elongation at break in the MD and TD directions was measured using an Autograph AG-IS (Shimadzu Corporation). The width of the sample film was 10 mm, the distance between chucks was 50 mm, and the tensile speed was 50 mm / min (strain rate = 100% / min). The tensile elongation at break was measured for samples cut from the film in the MD or TD direction to a length of 150 mm and a width of 10 mm. However, the tensile elongation at break of the film is the measurement result when a strip-shaped non-permeable, breathable film-like protective material is unfolded and pulled from a half-folded state. If the length of the measurement sample is short and the distance between chucks cannot be met, the distance between chucks may be narrowed. In this case, a tensile speed at which the strain rate becomes 100% / min should be selected.

[0067] (Melting point of the film (Tm)) The film, prepared by the inflation method according to the aforementioned "Film Production Method," was measured in accordance with JIS K 7121.

[0068] (Glass transition temperature (Tg) of the second surface layer of the film) The film, prepared by the inflation method according to the aforementioned "Film Production Method," was measured in accordance with JIS K 7244-2. Normal force: -0.3N • Swing angle: 0.1% • Frequency: 1Hz • Heating rate: 1.5℃ / min

[0069] The obtained film was cut along the MD direction to form strips 40 mm wide, which were then wound into rolls.

[0070] [Sewing thread] Gunze Corporation's airbag sewing thread (total fineness 1880 dtex, nylon 66 multifilament fiber 940 dtex 2-ply) was used for both the upper and lower threads.

[0071] [sewing machine] JUKI Corporation's LU-2210W-7 was used for sewing each component of the airbag.

[0072] [Heat welding] For welding the protective material to the main panel, a continuous-feed type small hot plate device LHP-PP1 (welding machine (belt heat press)) manufactured by Quinlight Electronics Precision Co., Ltd. was used. The upper heater temperature was set to 230°C, the lower heater temperature to 190°C, and the feed speed to 0.3 m / min, and the device was applied to sandwich the main panel from above and below. As shown in Figure 10, by using this device, efficient heat conduction is possible through the upper and lower heating and cooling plates, and by controlling the temperature, it is possible to form a bond with sufficient strength while applying heat to the bonding area while avoiding melting damage to the panel base fabric.

[0073] [Thermal welding (2step)] First, the upper heater temperature of the belt heat press machine was set to 100°C, the lower heater temperature to 230°C, and the feed speed to 1.0 m / min. Using a Ryobi hot air gun (HAG-1551), the entire film was heated to 100°C on one main panel, and the tape was fed while tension was applied. The tape was then welded onto the first base fabric by heating from below (step 1). After that, the second base fabric was placed on top of the tape, and using a hot plate jig with a shape matching the bonding area from step 1, it was pressed together for 3 seconds at a bonding temperature of 190°C (step 2).

[0074] [Half-fold former (tape bending jig)] The tape was folded in half just before welding using the tape bending jig shown in Figure 12. Because the edges of the film folded in half through the half-fold former may be misaligned, it was necessary to manually align the misaligned ends after it came out of the half-fold former.

[0075] [Preparation of a strip-shaped, half-folded film (heat tensile method)] In Examples 1 to 8, the 40 mm wide strip of film was processed into a 20 mm wide half-folded film using the half-folding device shown in Figure 8, and then wound onto a roll.

[0076] [Preparation of a strip-shaped, half-folded film (room temperature fixing method)] In Comparative Example 1, the pre-folded coated fabric or laminated base fabric was wound onto a roll, and a portion equal to the length of the airbag's outer edge stitching was cut and used.

[0077] [Fabrication of the main (base fabric) panel] As the main panel of the airbag's inflatable section, two pieces of base fabric cut to the shape shown in Figure 1 were layered together with the uncoated sides facing inward. After inserting and welding the protective material described later, the outer perimeter was sewn using the aforementioned sewing machine with the aforementioned sewing thread at a rate of 50 stitches per 10 cm, resulting in a seam allowance of 10 mm. Three backstitches were added at the beginning and end of the sewing.

[0078] [Inner tube fabrication] As an inner tube to be inserted inside the air inlet of the airbag, two pieces of the Si-coated fabric, cut to the shape shown in Figure 1, were used. The coated sides were placed on top of each other with the coated sides facing inward, and both ends were sewn together with the sewing machine using the sewing thread at a rate of 50 stitches per 10 cm, with a seam allowance of 10 mm. Three backstitches were made at the beginning and end of the sewing.

[0079] (1) Percentage of internal pressure retention after 6 seconds (%) An inner tube was inserted through the mounting opening of the main panel, which was sewn according to the specifications described below, and the positional relationship between the main panel and the inner tube was adjusted to create an evaluation airbag. The airbag was placed in a 0.22-liter tank filled with room-temperature helium to achieve an internal pressure of 8800 kPa. A metal pipe (inner diameter 21.3 mm) was connected to the front of the tank, and a solenoid valve attached near the front of the tank was opened and closed instantaneously. Subsequently, the change in the internal pressure of the airbag over time was measured using a pressure sensor (PGMC-A-1MPa manufactured by Kyowa Electric Industry Co., Ltd.) attached near the connection point between the pipe and the airbag. The internal pressure of the airbag 6 seconds after the solenoid valve opened was recorded by dividing it by the maximum internal pressure of the airbag after the solenoid valve opened. The test was performed once for each of the three airbags, and the average of the three measurement results was calculated as the internal pressure retention rate after 6 seconds, expressed as a percentage.

[0080] (2) Thickness after folding (mm) The straight seam section (section B in Figure 1) of the main panel, sewn according to the specifications described below, was cut to create a 60mm x 30mm sample piece for thickness evaluation. A 30mm x 30mm folded sample was created by folding the cut sample piece in half perpendicular to the straight seam. Using a Mitutoyo digital caliper (ABS Digimatic Caliper CD-20APX), the caliper's measuring part was used to clamp 10mm from the fold to the seam of the folded section and pressed with a force of 300gf, and the value was recorded. The test was performed once on each of the three airbags, and the average of the three measurement results was taken as the thickness after folding.

[0081] (3) Film modulus (MPa) in the MD and TD directions The tensile modulus of the film was measured using an Autograph AG-IS (Shimadzu Corporation) in an atmosphere of 23°C and 50% RH. Following the method described in ASTM-D-882, the tensile modulus was determined from the stress when a sample of the film, cut in the MD or TD direction, was displaced from 0.05% to 0.25% under conditions of a tensile speed of 5 mm / min (strain rate = 5% / min) and a chuck distance of 100 mm. However, the tensile modulus of the film referred to here is the measurement result obtained when a strip-shaped non-permeable, breathable film-like protective material was unfolded from a folded state and pulled. If the length of the measurement sample is short and the above chuck distance cannot be met, the chuck distance may be narrowed. In this case, a tensile speed that results in a strain rate of 5% / min should be selected.

[0082] (4) Evaluation of handling during R section machining When manufacturing airbags according to the specifications described below, the workers performing the bonding work were asked to evaluate the ease of deformation in curved sections and the handling of the film (presence or absence of film misalignment or curling, and whether the film was soft and difficult to handle) for each specification on a four-point scale (A: very easy, B: easy, C: somewhat difficult, D: difficult, E: impossible). A total of five workers provided evaluations, and the most frequent response was used as the evaluation result for handling during R section processing.

[0083] (5) Manufacturing time per bag The time required from the process of cutting sample pieces from the sample fabric to producing three bags sewn according to the specifications described below was divided by 3 to determine the production time per bag, and this was expressed as an index with Example 1 set as the baseline of 100. However, the process of producing the protective material was carried out and prepared in advance.

[0084] [Examples 1-8, Comparative Example 1] In Examples 1, 2, 4, 7, 8, and Comparative Example 1, the protective material used was a multilayer film consisting of an adhesive layer, an intermediate layer, resin layer 1, and resin layer 2. PA6 / 12 was used for the adhesive layer, POm-PE for the intermediate layer, PA6 / 66 polymer for resin layer 1, and PE (LDPE) for resin layer 2. These were extruded from a multilayer circular die and produced by inflation to create four types of four-layer films with a thickness of 30 μm. By changing the layer ratio of each resin layer, films with different film moduli in the MD direction and TD direction were obtained. In Example 3, the protective material used was a multilayer film consisting of "adhesive layer / resin layer 1 / intermediate layer / resin layer 1 / resin layer 2 / resin layer 3". PA6 / 12 was used for the adhesive layer, PO for resin layer 1, PO elastomer for the intermediate layer, PA6 / 66 polymer for resin layer 2, and PE (LDPE) for resin layer 3. These materials were extruded from a multilayer circular die and produced a 30 μm thick, 6-layer film of 5 types by the inflation method. In Examples 5 and 6, the protective material used was a multilayer film consisting of an adhesive layer, an intermediate layer, and a resin layer 1. The adhesive layer was made of PA6 / 66 polymer, the intermediate layer of POm-PE, and the resin layer 1 of PA6 / 66 polymer. These materials were extruded from a multilayer circular die and produced a 30 μm thick, 2-type, 3-layer film by inflation. Table 1 below describes the physical properties of the multilayer films obtained and the evaluation results of airbag test pieces using them as protective materials.

[0085] [Table 1]

[0086] In Example 1, a multilayer resin film with four layers of four different types was used as the non-permeable film-like protective material. The elastic modulus of this film in the MD direction was 245 MPa, and the elastic modulus in the TD direction was 250 MPa. In the fabrication of the airbag, a method was used in which a strip-shaped non-permeable film-like protective material was sandwiched along the straight or curved outer edge of a pair of base fabric panels. This method involved preparing a roll from which a half-folded film had been wound, and then feeding the strip-shaped non-permeable film-like protective material from this roll to the heat-sealing location. This method provided good handling during R-section processing, and the resulting airbag exhibited high internal airbag pressure retention and good compactness.

[0087] In Example 2, the process was the same as in Example 1, except that the elastic modulus of the film in the MD direction was 200 MPa and the elastic modulus in the TD direction was 200 MPa. With this method, handling during R-section processing was very good, and the resulting airbag had a high internal pressure retention rate and good compactness.

[0088] In Example 3, the process was the same as in Example 1, except that the elastic modulus of the film in the MD direction was 300 MPa and the elastic modulus in the TD direction was 290 MPa. In this method, the film was somewhat stiff and difficult to deform, resulting in slightly worse handling performance during R-section processing. However, the resulting airbag had a high internal airbag pressure retention rate and good compactness.

[0089] In Example 4, the process was the same as in Example 1, except that the elastic modulus of the film in the MD direction was 150 MPa and the elastic modulus in the TD direction was 125 MPa. With this method, the film was soft and sometimes difficult to handle, resulting in slightly worse handling performance during R-section processing. However, the resulting airbag had a high internal airbag pressure retention rate and good compactness.

[0090] In Example 5, a multilayer resin film with two types and three layers was used as the non-permeable film-like protective material. When manufacturing the airbag, a method was used to sandwich a strip-shaped non-permeable, non-permeable, breathable film-like protective material along the straight or curved outer edge of a pair of base fabric panels. A roll of half-folded film was prepared in advance, and a 20 mm wide PE film (50 μm thick) was inserted as release paper inside the fold of the half-folded film. The strip-shaped non-permeable film-like protective material was then fed from this rolled-up roll to the heat-sealed welding location. With this method, handling was sometimes difficult due to the displacement of the release paper, and handling performance during R-section processing was slightly worse. However, the resulting airbag had a high airbag internal pressure retention rate and good compactness.

[0091] In Example 6, the same film as in Example 5 was used, but a roll of unfolded strip-shaped film was prepared in advance. The strip-shaped non-breathable film protective material was then folded in half using a half-fold former during the process of feeding it from the roll to the heat-sealing location. A 20mm wide PE film (50μm thick) was then sandwiched inside the fold of the half-folded film as a release liner before feeding it to the heat-sealing location. This method was prone to misalignment of the release liner and film, making it difficult to handle and worsening handling performance during R-section processing. However, the resulting airbag had a high internal airbag pressure retention rate and good compactness.

[0092] In Example 7, the same film as in Example 1 was used, but a roll of unfolded strip-shaped film was prepared in advance. The strip-shaped non-breathable film protective material was then folded in half using a half-fold former during the process of feeding it from this roll to the heat-sealing location before being fed to the location. With this method, the film was prone to shifting and curling, making it difficult to handle, and the handling performance during R-section processing was slightly worse. However, the resulting airbag had a high internal airbag pressure retention rate and good compactness.

[0093] In Example 8, the same film as in Example 1 was used, but when manufacturing the airbag, instead of sandwiching a strip-shaped non-permeable, breathable film-like protective material along the straight or curved outer edge of a pair of base fabric panels, a tape was fed onto a single main panel while applying tension, and the tape was welded onto the first base fabric by heating from below (step 1). Then, a second base fabric was placed on top of the tape and pressed down (step 2). This method resulted in good handling during R-section processing, a short manufacturing time per bag, and the resulting airbags had a high airbag internal pressure retention rate and good compactness.

[0094] In Comparative Example 1, the same film as in Example 1 was used, but when manufacturing the airbag, the film-like protective material was sandwiched between two panel cloths so that it formed a loop on the inside of the airbag. After sewing the panel cloths together, the protective material and the laminated surface of the panel cloth were heat-sealed on the inside of the seam. During bonding, the protective material was fixed by sewing, so no tension was applied to the protective material during bonding. With this method, the film was prone to shifting and wrinkling, making it difficult to handle, and the handling performance during R-section processing was poor. In addition, the manufacturing time per bag was long, and the resulting airbags had a low airbag internal pressure retention rate and poor compactness. [Industrial applicability]

[0095] The method for manufacturing an airbag according to the present invention involves bonding the outer surfaces of both ends of a folded, non-breathable protective material to the inner surface of each of at least one pair of base fabric panels in an adhesive region of a predetermined width along the suture, having a proximal end and a distal end extending from near the suture towards the inside of the bag. This method provides a highly productive method for manufacturing airbags that offer high internal pressure retention, low cost, high productivity, and excellent compactness. Therefore, the method for manufacturing airbags according to the invention is suitably applicable to automotive airbags, CABs (Computer Airbags) where internal pressure retention performance is particularly required, and pedestrian airbags. [Explanation of Symbols]

[0096] 1. Base fabric panel (panel fabric, main panel) 1' Base fabric panel (panel fabric, main panel) 2 Suture (sewing) part 2' Isolated suture (sewing) part 3. Silicone adhesive 4. Non-breathable (film-like) protective material 4' Inner edge of non-breathable (film-like) protective material 4" half-folded strip-shaped non-breathable (film-like) protective material 5 Adhesion area 5' adhesive area 6. Proximal end of the bonding area 6' Proximal end of the adhesive region 7. Distal end of the adhesive area 7' Distal end of the adhesive area 8. End (sealing) portion of non-breathable (film-like) protective material 8' End (sealing) portion of non-breathable (film-like) protective material 10. Bag-shaped airbag with sutured outer edges AA cross section 11 Multilayer film 11a Multilayer film (outer layer) 11b Multilayer film (adhesive layer) 12 multilayer dies 13 Air Ring 14. Deflator (Free Roll) 15. First pinch drive roll 16 Guide Roll (Free Roll) 17 Second pinch drive roll 18 Touch Roll (Free Roll) 19. Winding drive roll 20 Nylon 66 base fabric 21. Pressure Roll (Silicone Rubber Lining) 22. Heated Roll (Chrome Plated) 23 Inner Tubes 24. Inner tube stitching

Claims

1. A method for manufacturing an airbag comprising at least one pair of base fabric panels sewn together at their outer edges, comprising the following steps: A welding process is performed in which a folded strip-shaped non-breathable film-like protective material, consisting of a single-layer resin film with a release liner sandwiched between the inner surfaces of a pair of base fabric panels, or a laminated resin film consisting of two or more layers including a first surface layer and a second surface layer, is sandwiched between the inner surfaces of each of the pair of base fabric panels while tension is applied, and heat or ultrasonic waves are applied from the outside of the pair of base fabric panels to weld the surface of the single-layer resin film or the first surface layer to the inner surface of the base fabric panel in an adhesive area of ​​a predetermined width. Here, the surfaces of the single-layer resin film on the release liner side are not welded together due to the presence of the release liner, or the second surface layers of the laminated resin film are not welded together by heat welding or ultrasonic welding, or are welded together by heat welding or ultrasonic welding, but when tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the second surface layer peels off; A suturing step of sewing the pair of base fabric panels together near the bonded area before, after, or simultaneously with the welding; The manufacturing method, including the above.

2. The method according to claim 1, wherein the folded strip-shaped non-breathable film-like protective material is fed out from a roll in which it has been wound in a folded state and sandwiched between a pair of base fabric panels.

3. A step of heating part or all of the folded, non-breathable film-like protective material before the welding step of welding the folded, non-breathable film-like protective material; The method according to claim 1 or 2, including the method described in claim 1 or 2.

4. A step of cooling part or all of the folded, non-breathable film-like protective material after a welding step in which the folded, non-breathable film-like protective material is welded together; The method according to claim 1 or 2, including the method described in claim 1 or 2.

5. In a welding process for welding the aforementioned folded strip-shaped non-breathable film-like protective material, a step is to heat and / or cool a part or all of the folded strip-shaped non-breathable film-like protective material while intermittently applying and releasing pressure from a hot plate and / or a cooling plate; The method according to claim 1 or 2, including the method described in claim 1 or 2.

6. The method according to claim 1 or 2, wherein the melting point of the resin constituting the first surface layer of the folded, non-breathable film-like protective material, a laminated resin film, is 50°C to 160°C lower than the melting point of the resin constituting the second surface layer.

7. In the aforementioned folded non-breathable film-like protective material, a multilayer film including a first surface layer and a second surface layer of a single-layer or laminated resin film, the difference in SP values ​​between any adjacent layers is 2.0 [cal / cm²]. ３ ) １／２ The method according to claim 1 or 2, wherein the method is as described above.

8. In the aforementioned folded non-breathable film-like protective material, a multilayer film including a first surface layer and a second surface layer of a single-layer or laminated resin film, the difference in HSP value between any adjacent layers is 1.0 [cal / cm²]. ３ ) １／２ The method according to claim 1 or 2, wherein the method is as described above.

9. The method according to claim 1 or 2, wherein, when a tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the length between the distal ends along the folded non-breathable film-like protective material is greater than or equal to the length between the distal ends along the pair of base fabric panels.

10. A sewing step is performed in which the pair of base fabric panels are sewn together near the bonded area after the welding; The method according to claim 1 or 2, including the method described in claim 1 or 2.

11. A method for manufacturing an airbag comprising at least one pair of base fabric panels sewn together at their outer edges, comprising the following steps: A welding process in which, while applying tension to a folded strip-shaped non-breathable film-like protective material consisting of two or more laminated resin films including a first surface layer and a second surface layer, with a predetermined width, heat or ultrasonic waves are applied continuously from the underside of the base fabric panel, along the straight or curved outer edge of the base fabric panel, to weld the first surface layer to the upper surface of the base fabric panel; A welding process in which another base fabric panel is placed on top of the welded film-like protective material, and heat or ultrasonic waves are applied from the upper side of the overlapping base fabric panel to weld the first surface layer to the lower surface of the overlapping base fabric panel, wherein the second surface layers of the laminated resin film are not welded together by heat welding or ultrasonic welding, or are welded together by heat welding or ultrasonic welding, but when tensile force is applied to the base fabric panels during the deployment of the airbag, the second surface layer peels off; A sewing step is performed in which the base fabric panel is sewn together near the area of ​​the welded region after the welding; The manufacturing method, including the above.

Images