Airbag with enhanced internal pressure retention performance and its manufacturing method

Abstract

Provided are: an airbag that has high internal-pressure retention performance, has high productivity with low cost, is environmentally friendly, and has excellent compactness; and a method for manufacturing the same. The present invention provides an airbag having at least a pair of base fabric panels sewn at outer peripheral edges thereof. The airbag has an airtight structure in which outer surfaces at both ends of a belt-shaped half-folded air-impermeable film-like protective material are adhered, in a straight line or a curved line, to respective inner surfaces of the pair of base fabric panels in an adhesion region having a prescribed width and extending along the seam. The half-folded air-impermeable 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. The first surface layer is welded to the base fabric panels. The opposing portions of the second surface layer are not adhered to each other, or even if said portions are adhered to each other, when the tensile strength is applied to the pair of base fabric panels at the time of deployment of the airbag, the second surface layer is peeled off, whereby the airtight structure in the adhesion region is maintained.

Description

[Technical Field]

[0001] This invention relates to an airbag used in an airbag system installed in a vehicle. More specifically, it relates to an airbag in which the outer edges of a pair of base fabric panels are sewn together, and to an airbag with enhanced internal pressure retention performance, and to a method for manufacturing the same. [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 is to adhere the outer edges of a pair of base fabric panels solely with an adhesive instead of sewing. Although gas leakage can be suppressed with such a method, since there is no sewing, there is a risk that the adhesion may not withstand the strength during airbag deployment.

[0005] Another method is to manufacture a pair of base fabric panels using bag woven OPW (One Piece Woven) and coat them from the outside of the base fabric. With such a method, since there is no sewing and there is a coating, there is no problem with airtightness, and there is also no problem with strength. However, it is difficult to create a complex shape, it is necessary to apply the coating relatively thickly, which tends to increase the weight of the airbag, and there is also a problem of high cost.

[0006] Furthermore, another method is to adhere the outer edges of a pair of base fabric panels with a silicone adhesive and then sew the adhered parts. This method can suppress gas leakage and ensure strength, but there are problems such as low productivity, the adhered parts becoming thick, and the folding and storage properties of the airbag deteriorating. Also, due to the weight of the silicone adhesive, the weight of the airbag increases. As illustrated in FIG. 2, in this method, when the airbag is deployed, the silicone adhesive stretches and access of gas to the sewing part is avoided. Generally, silicone adhesives are suitable for such applications because they have high adhesion strength to the base fabric panel. However, it takes half a day to about one day for the adhesive to cure, resulting in low productivity. Also, for example, under certain conditions, the folding thickness of a pair of base fabric panels at a location where there is no adhesive (a location where internal pressure retention is not required) is 2.2 mm, while the folding thickness at a location with adhesive and sewing is 5.2 mm, lacking in compactness (folding and storage properties). Furthermore, silicone adhesives need to be separated from the airbag fabric during recycling, and the GHG (Green House Gas) emissions during production are also relatively high, so it cannot be said that it is environmentally friendly in the manufacture and disposal of airbags.

[0007] Patent Document 1 below describes an airbag device having a protective fabric sewn along a stitching portion so as to cover the stitching portion from the inside where gas from an inflater is introduced, at a position away from the stitching portion where opposing portions of a base fabric are stitched together in pairs (see FIGS. 2 and 7 of the same document). Patent Document 1 discloses a protective material for the stitching portion, but such a protective material is fixed by sewing rather than being adhered to the base fabric. The purpose of such a protective material is to prevent the stitching portion from being directly exposed to and damaged by the high-pressure gas from the inflater, and also to disperse the tension at the stitching portion of the protective material to prevent breakage of the stitching portion of the pair of base fabrics, and it is not for the purpose of maintaining the internal pressure in a state where the stitching portion does not break.

[0008] Patent Document 2 below describes an airbag having a wall portion including a laminate material, the laminate material including a backing layer having a breathable sheet-like structure made of a woven or knitted fabric, at least two layers of coextruded polymer films, a first polymer layer having a predetermined glass transition temperature on the backing layer side, and a second polymer layer having a predetermined storage modulus on the side opposite to the backing layer, an airbag in which the wall portions are joined such that the second polymer layer is joined at the edge of the airbag, and a manufacturing method of joining by applying different thermal energies to the first polymer layer and the second polymer layer are disclosed. The object of the invention described in Patent Document 2 is to provide an airbag that can be produced at low cost and is easy and reliable to seal (see FIGS. 1-3 of the same document). Patent Document 2 does not disclose a protective material for the airbag stitching portion, and its manufacturing method is mainly aimed at improving productivity and not at maintaining internal pressure.

[0009] Patent Document 3 describes an airbag in which panels are joined together at a joint, the panel having a woven fabric and a synthetic resin film bonded to the woven fabric via an adhesive, the panels being joined together by pressing and heating with a hot melt adhesive sheet interposed between them, and the synthetic resin film being placed on the outside of the airbag. The object of the invention described in Patent Document 3 is to provide an airbag that has high strength at the seams between the panels, excellent durability, prevents gas leaks, and is easy to handle (see Figures 3 and 4). In the invention described in Patent Document 3, the strength of the joint between panels is increased by bonding them together with a bonding layer made of hot melt adhesive, the thread density of the woven fabric is reduced, and a synthetic resin film is placed on the outside of the panel to avoid direct contact of the woven fabric with the inner surface of the vehicle body, thereby increasing durability. Furthermore, the hot melt adhesive is impregnated into the seams of the woven fabric to prevent gas leakage from needle holes and thread slippage in the seams. Patent Document 3 does not describe a method to prevent gas leaks from stitching holes when stress is applied to the outer adhesive surface of the airbag during airbag deployment, causing stress to be applied to the joints between panels, leading to adhesive failure. Furthermore, it does not describe a technical concept of adhering a protective material to the base fabric at a location separate from the stitching, and maintaining the adhesion between the protective material and the base fabric to maintain internal pressure.

[0010] Thus, in light of the current state of technology, an airbag that excels in maintaining internal pressure during inflation and deployment, and is also highly compact, and a method for manufacturing such an airbag, have not yet been provided. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] International Publication No. 2010 / 122852 [Patent Document 2] U.S. Patent Application Publication No. 2010 / 0320736 [Patent Document 3] Japanese Patent Publication No. 2018-177122 [Overview of the project] [Problems that the invention aims to solve]

[0012] Given the current state of prior art, the problem that the present invention aims to solve is to provide 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 strip-shaped non-permeable 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 that enhances internal pressure retention performance while also being compact, and a method for manufacturing the same. [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] In an airbag in which at least one pair of base fabric panels are sewn together at the outer edge, An airbag wherein the outer surfaces of both ends of a folded, non-breathable film-like protective material are bonded to the inner surface of each of the pair of base fabric panels in a predetermined width adhesive region along the suture, having 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 adhesive region being 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 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. [2] The airbag according to [1], 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. [3] The airbag according to [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 60°C to 160°C lower than the melting point of the resin constituting the second surface layer. [4] 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 values ​​between any adjacent layers is 2.0 [cal / cm 3 ) 1 / 2 An airbag as described in any of the above [1] to [3], which is greater than or equal to [1]. [5] 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 HSP value between any adjacent layers is 1.0 [cal / cm 3 ) 1 / 2 An airbag as described in any of the above [1] to [4], which is greater than or equal to [1]. [6] The airbag according to any one of [1] to [5], wherein the glass transition temperature (Tg) of the resin constituting the second surface layer is 0°C or higher. [7] When the airbag is deployed, when a tensile force is applied between the pair of base fabric panels, 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, according to any of [1] to [6] above. [8] The airbag according to any one of [1] to [7], wherein the thickness of the non-breathable protective material is 0.001 mm or more and 0.5 mm or less. [9] An airbag according to any of [1] to [8], wherein the tensile modulus of the folded strip-shaped non-breathable protective material is 100 to 800 MPa.

[10] The airbag according to any one of [1] to [9], wherein the adhesive strength in the adhesive region is 1 N / cm or more.

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

[10] , wherein the airbag has an R portion with a radius of curvature of 300 mm or less in the adhesive area.

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

[11] , wherein the airbag has an inverted R portion with a radius of curvature of 300 mm or less in the adhesive region.

[13] The airbag according to

[11] or

[12] , wherein the surface step of the R portion is 400 μm or less.

[14] An airbag according to any one of

[11] to

[13] , wherein the ratio (R portion / straight portion) of the surface step (peak-valley difference) of the R portion to the surface step (peak-valley difference) of the substantially straight portion excluding the R portion is 0.6 to 2.0.

[15] The airbag according to any one of

[11] to

[14] , wherein the adhesive strength in the R portion is 1 N / cm or more.

[16] An airbag according to any one of

[11] to

[15] , wherein the ratio of the adhesive strength in the R portion to the adhesive strength of the substantially straight portion excluding the R portion (R portion / substantially straight portion) is 0.5 to 2.5.

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

[16] , wherein the airbag includes an isolated seam forming a closed space.

[18] The airbag according to

[17] , wherein in the isolated sewing portion, there is a portion where the folded strip-shaped non-breathable protective material overlaps.

[19] The airbag according to

[18] , wherein there are areas where the folded strip-shaped non-breathable protective material overlaps, and the non-breathable protective material is not bonded to itself.

[20] 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 step of inserting a non-breathable film-like protective material, which is a folded strip or a shape conforming to the shape of the base fabric panel, made of a laminated resin film of a predetermined width and consisting of two or more layers including a first surface layer and a second surface layer, between the inner surfaces of each of the pair of base fabric panels along the outer edge of the pair of base fabric panels; A welding process in which heat or ultrasonic waves are applied from the outside of the pair of base fabric panels to weld the first surface layer to the inner surface of the base fabric panels, wherein the second surface layers are not welded to each other, or are welded to each other 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; A suturing step of sewing the pair of base fabric panels together in the vicinity of the resulting welded area before, after, or simultaneously with the aforementioned welding; The manufacturing method, including the above.

[21] The method according to

[20] , 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.

[22] 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 values ​​between any adjacent layers is 2.0 [cal / cm 3 ) 1 / 2 The method according to

[20] or

[21] , wherein the method is greater than or equal to

[20] .

[23] 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 HSP values ​​between any adjacent layers is 1.0 [cal / cm 3 ) 1 / 2 The method according to any of the above

[20] to

[22] , wherein the method is greater than or equal to

[20] .

[24] The method according to any one of

[20] to

[23] , wherein, when a tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the distance between the distal ends along the folded non-breathable film-like protective material is greater than or equal to the distance between the distal ends along the pair of base fabric panels. [Effects of the Invention]

[0015] The airbag and its manufacturing method according to the present invention are characterized in that, on the inner surface of each of at least one pair of base fabric panels, the outer surfaces of both ends of a strip-shaped non-breathable protective material are bonded to each of the inner surfaces of the 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, and when tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the adhesive region is substantially free from tensile force, thus maintaining an airtight structure. As a result, the airbag has high internal pressure retention performance and is also compact, and the manufacturing method for the airbag is highly productive. Therefore, the airbag and its manufacturing method according to the invention are suitably applicable to automotive airbags, CABs (Computer Airbags) where internal pressure retention performance is particularly required, and pedestrian airbags. [Brief explanation of the drawing]

[0016] [Figure 1] This is a plan view of an airbag in which a pair of base fabric panels 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 the airbag of this embodiment when the airbag is deployed. [Figure 4] This diagram illustrates a state in the airbag of this embodiment in which, 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 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 4(a) shows the first pattern, and Figure 4(b) shows the second pattern (loop outside, film folded and stored). [Figure 5] This diagram illustrates a state in which a strip-shaped, 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 strip-shaped, 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, 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 strip-shaped, non-breathable film-like protective material. [Figure 8] 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 9] This is an explanatory diagram of a method for producing a laminated (base) fabric by using a laminator to bond a multilayer film to a silicone rubber roll. [Figure 10] This is an explanatory diagram for the method of creating and bonding a non-breathable protective material by laminating two protective materials cut into the base fabric panel shape (horseshoe shape) shown in Figure 1. Two pieces of resin film, coated fabric, or laminated base fabric cut into the desired shape are used, and the outer layers of one end (inner edge side) of a multilayer film (for example, in the case of a multilayer film, peel off a part of the second surface layer and align the first surface layers) or the uncoated surfaces of the base fabric are overlapped, and they are bonded together along the inner edge by welding or adhesive so that the length from the outer edge is a predetermined length. [Figure 11] 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 12] This is an explanatory diagram of one method for adhering a folded film to an isolated seam in a closed space. [Figure 13] Figure 12 is an explanatory diagram of the sealing state according to method 1. [Figure 14] This diagram illustrates another method of adhering a folded film to an isolated seam in a closed space, and the resulting sealing state. [Figure 15]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 16] 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 17] This diagram illustrates the supply state of a folded film in a welding process in which a half-folded, strip-shaped, non-permeable 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 18] 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. One embodiment of the present invention is an airbag in which at least one pair of base fabric panels are sewn together at their outer edges, The airbag is such that, on the inner surface of each of the pair of base fabric panels, the outer surfaces of both ends of a folded, strip-shaped, 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.

[0018] [Base fabric panel (panel fabric, main panel)] There is no particular limitation on the pair of base fabric panels, and they can be plain-woven fabrics of polyamide or polyester commonly used as the base fabric of airbags. The fineness of the fibers constituting the base fabric used in this embodiment is preferably 150 to 900 dtex. By having a fineness of 150 dtex or more, the strength as an airbag can be obtained, and by having a fineness of 900 dtex or less, a flexible base fabric for an airbag can be obtained. It is preferable to use multifilaments for the fibers constituting the base fabric used in this embodiment, and the fineness of the single filament of the fiber is preferably 0.1 to 10 dtex. Within this range, a flexible base fabric for an airbag with a high deployment speed can be obtained. Also, the weave density of the base fabric used in the present invention is preferably 30 to 90 threads / inch for both warp and weft, and the cover factor is preferably 1500 to 2500. Within this range, a flexible base fabric for an airbag with sufficient strength to withstand deployment can be obtained. However, the cover factor is a value calculated by the following formula. CF = (number of warp threads per 2.54 cm) × √(total fineness of warp (dtex)) + (number of weft threads per 2.54 cm) × √(total fineness of weft (dtex))

[0019] In order to reduce the air permeability, the base fabric panel is preferably one coated with resin on both sides or one side, or laminated with a single-layer or multi-layer film. At this time, as the resin used for the resin coating, methods such as silicone-based or polyurethane-based coatings, and thermal lamination using a flame-retardant thermoplastic resin film can be adopted. When coating with resin, the coating amount is preferably 5 to 50 g / m 2 When laminating a film to the base fabric, the thickness of the film is preferably 0.001 mm or more and 0.5 mm or less. Within this range, a flexible base fabric for an airbag with excellent airtightness can be obtained. 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.

[0020] [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 single-ply yarn, or a double-ply yarn made by twisting two or more single-ply fibers 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.

[0021] [A strip-shaped, 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.

[0022] In this embodiment of the airbag, instead of a silicone adhesive, a strip-shaped non-breathable film-like protective material is bonded to the inner surface of each of a pair of base fabric panels in a predetermined width 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 both outer surfaces of the strip-shaped non-breathable film-like protective material forming a straight or curved line. 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. 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. Such a feature structure may be used in the entire outer perimeter of the airbag or in a part of the airbag. Here, "a part" means, for example, 50% or more. When such a feature structure is used in a part of the airbag, silicone adhesive can be used, for example, in the seams of the airbag that may cause other gas leaks in order to obtain airtightness of the entire airbag. Furthermore, such a feature structure is applicable 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 shape of the seam lines between the pair of base fabric panels may be different, resulting in three-dimensional stitching.

[0023] 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 airbags composed only of two base fabric panels made by overlapping two base fabric panels of the same shape, as shown in Figures 1 and 15, 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.

[0024] 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.

[0025] Figure 3 illustrates the state of the folded, non-breathable film protective material when the airbag is deployed. As can be seen from Figure 3, the folded, non-breathable film protective material forms a loop shape toward the inside of the airbag, creating an airtight structure in the area where it is bonded to the base fabric panel, thus providing internal pressure retention.

[0026] In the airbag of this embodiment, when the airbag is deployed, the length between the distal ends along the folded film-like 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 suture during deployment, virtually 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 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 will be stretched by the tensile force applied during airbag deployment, and if the suture breaks first, virtually no force will be 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 film-like 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.

[0027] In this specification, the term "half-folded (film-like) non-permeable protective material" includes not only those that are folded in half when an airbag is contained, 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 folded in half, but also those that are folded multiple times, such as in an accordion shape, and those made by overlapping two strip-shaped (including curved) single-layer or multi-layer resin films and bonding or welding one end with adhesive (i.e., those made by a two-layer bonding method). Such a strip-shaped, half-folded, non-breathable protective material may be bonded to the base fabric in a straight or curved line along the seam, or two pieces of resin film cut into a desired shape may be used, and the outer layers of one end (inner edge side) of a multilayer film (for example, in the case of a PE (second surface layer)-PA6 / 12 (first surface layer) multilayer film, a part of the second surface layer may be peeled off and the first surface layers may be joined together) and welded along the inner edge, for example with a width of 5 mm, so that the length from the outer edge is a predetermined length, or bonded together with, for example, a cyanoacrylate-based instant adhesive (manufactured by Konishi Co., Ltd.), and allowed to dry completely (i.e., not in the form of a strip, but for example, by bonding two pieces of protective material cut into the shape of a base fabric panel (horseshoe shape) as shown in Figure 1) (see Figure 10). However, rather than manufacturing the protective material by laminating two pieces together, it is preferable to manufacture it by continuously supplying a strip of a single resin film folded in half and heat-welding it while applying tension, as shown in Figures 15-17.

[0028] 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.

[0029] When a resin film is used as a half-folded non-breathable protective material, by using a manufacturing method such as the one 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.

[0030] As long as the non-breathable film-like protective material is not damaged during airbag inflation and deployment, there are no particular restrictions, 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 film-like protective material and the base fabric panel, recyclability can be improved.

[0031] 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.

[0032] As shown in Figures 4(a) and (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 (not shown). 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 region 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, thereby forming an airtight structure in the adhesive region with the base fabric panels. 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. The adhesive properties can be improved by changing the material of the protective material and welding conditions.

[0033] In the airbag of this embodiment, the thickness of the non-breathable film-like protective material is preferably 0.001 mm or more and 0.5 mm or less, more preferably 0.001 mm or more and 0.1 mm or less, and even more preferably 0.005 mm or more and 0.05 mm or less, from the viewpoint of folding thickness.

[0034] In the airbag 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 due to the film peeling off from the base fabric panel due to the air pressure of the gas when the airbag deploys is greatly reduced.

[0035] 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 keeping the tensile breaking strength below 100 MPa, the rigidity is reduced, resulting in a film with good handling properties.

[0036] The airbag of this embodiment may have, in the adhesive area, 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 11. Here, an R-shaped section is a part of the stitching line along the outer edge of the base fabric panel that has a curved shape that is convex toward the side of the airbag's inflation chamber. For example, this corresponds to part X in Figure 1. On the other hand, an inverted R-shaped section is a part of the stitching line along the outer edge of the base fabric panel that has a curved shape that is convex toward the side of the airbag's inflation chamber. For example, this corresponds to part Y in Figure 1. In curved stitching sections including such R-shaped sections and inverted R-shaped 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 section and the normal section. The difference in height (peak-valley difference) between the wrinkled portion and the normal portion of the R-shaped section 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 having a surface height difference (peak-valley difference) of 400 μm or less in the R-shaped section, the difference in height between the wrinkled portion and the normal portion can be reduced to prevent stress concentration, suppress gas leakage from the adhesive portion, and result in an airbag with excellent storage capacity. 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.

[0037] 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) • Trend correction is performed only on the "flat" plane.

[0038] Furthermore, the adhesive strength (peel strength) in the adhesive region between the base fabric panel and the non-breathable protective material in the R section is preferably 1 N / cm or more, more preferably 2 N / cm or more, and even more preferably 3 N / cm or more. If the adhesive strength is 3 N / cm or more, the occurrence of leaks due to the film peeling off from the panel base fabric due to the gas pressure when the airbag deploys is significantly reduced. However, the adhesive strength (peel strength) in the adhesive region between the base fabric panel and the non-breathable protective material in the R section referred to here is calculated by taking two points on the sewing curve section (R section) with a shortest distance of 30 mm, and cutting the airbag into a 100 x 30 strip perpendicular to the line segment connecting the two points, as described in the measurement method for the adhesive strength (peel strength) (N / cm) between the protective material and the panel fabric in the R section later, and measuring the tensile strength of the test piece, and refers to a sample taken from an R section with a radius of curvature of 300 mm or less. Furthermore, the ratio of the adhesive strength in the R portion to the adhesive strength of the substantially straight portion excluding the R portion (R portion / substantially straight portion) is preferably 0.5 to 2.5, more preferably 0.7 to 2.0, and even more preferably 0.8 to 1.5. By setting the ratio of adhesive strength within the above range, there are no parts with extremely low adhesive strength throughout the airbag, which significantly reduces the occurrence of leaks caused by the film peeling off from the panel base fabric due to the gas pressure when the airbag deploys.

[0039] [Airbag manufacturing method] Another embodiment of this invention is a method for manufacturing an airbag in which a pair of base fabric panels are sewn together at their outer edges to form a bag, comprising the following steps: A step of inserting a non-breathable film-like protective material, which is a folded strip or a shape conforming to the shape of the base fabric panel, made of a laminated resin film of a predetermined width and consisting of two or more layers including a first surface layer and a second surface layer, between the inner surfaces of each of the pair of base fabric panels along the outer edge of the pair of base fabric panels; A welding process in which heat or ultrasonic waves are applied from the outside of the pair of base fabric panels to weld the first surface layer to the inner surface of the base fabric panels, wherein the second surface layers are not welded to each other, or are welded to each other 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; A suturing step of sewing the pair of base fabric panels together in the vicinity of the resulting welded area before, after, or simultaneously with the aforementioned welding; The manufacturing method may include the above.

[0040] As shown in Figures 5-7, when a single-layer resin film is used as the protective material for heat welding of the base fabric panel and the protective material by heating, inserting release paper inside the loop makes it possible to bond a protective material with a loop length sufficient to maintain airtightness in the bonded area. However, if a multilayer resin film is used as the strip-shaped protective material, and release paper is not used, the second surface layers on the inside of the loop are either not bonded to each other, or are welded by heat welding or ultrasonic welding, but the second surface layers are configured to peel off when tensile force is applied to the pair of base fabric panels during the deployment of the airbag. This configuration also improves the productivity of the airbag. Furthermore, with this configuration, even if it is difficult to remove the release paper from curved or circular shaped stitching of the airbag, the release paper does not remain inside the airbag, thus preventing an increase in the weight of the airbag or deterioration of its storage capacity, and also avoiding the release paper affecting the deployment speed and behavior of the airbag. Such a configuration, for example, ensures that the melting point of the resin constituting the first surface layer of the folded, non-breathable film-like protective laminated resin film 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 do not fuse together, or the SP values ​​of the resin constituting the first surface layer, the resin constituting the second surface layer, and the resin constituting the other layers of the folded, non-breathable film-like protective laminated resin film are set to 2.0 [cal / cm²] between adjacent layers. 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 the 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 describes such a configuration with reference to Figure 18. For example, the melting point of PA6 / 12 is 128°C, the melting point of TPEE is 216°C, the melting point of PA6 / 66 is 194°C, the melting point of PA12 elastomer is 176°C, the melting point of PO (acid-modified polyethylene) is 120°C, and the melting point of 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, and 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.

[0043] Here, the 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 adhesive strength with the base fabric panel can be increased, and fusion between the second surfaces can be made less likely. Furthermore, by setting the melting point difference to 160°C or lower, when producing a film by, for example, inflation molding, the flow unevenness and melt tension are properly maintained, thereby improving the stability of the 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.

[0044] 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 ].

[0045] For example, in the right-hand diagram of Figure 18 (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 structure consists of four layers, including an intermediate layer (acid-modified PE) and a high-melting-point layer (PA6 / 66). Here, not only is the difference in SP value between the high-melting-point layer (PA6 / 66) and the release layer (PE) important, but the difference in SP value between any adjacent layer constituting the first surface layer (adhesive layer (PA6 / 12), X layer (for example, intermediate layer (acid-modified PE), and high-melting-point layer (PA6 / 66)) 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.

[0046] 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.

[0047] 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. The SP values ​​of various resins are listed, for example, in "Various Standards and Usage Guide: 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 the SP value.

[0048] 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 making the value greater than 2.0 (cal / cm²). 3 ) 1 / 2) or more is more preferable, and 3.0 (cal / cm³) 3 ) 1 / 2 The above is even more preferable. 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).

[0049] 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.

[0050] Using the manufacturing method described above, an airbag can be formed in which at least one pair of base fabric panels are sewn together at their outer edges. On the inner surface of each of the pair of base fabric panels, the outer surfaces of both ends of a folded, non-breathable 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. The folded, non-breathable protective material is a laminated resin film consisting of two or more layers, including a first surface layer and a second surface layer. 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 when tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the second surface layers release tension, enabling the airbag to be provided with high productivity.

[0051] Furthermore, the airbag of this embodiment can also be manufactured (provided) with high productivity using the following manufacturing method. [Tension application, clamping method] 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 two or more laminated resin films of a predetermined width, 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 panels, wherein the second surface layers of the laminated resin films 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; A suturing step of stitching the pair of base fabric panels together near the area of ​​the resulting weld, before, after, or simultaneously with the aforementioned bonding; The manufacturing method, including the above.

[0052] In the above manufacturing method, for ease of welding the film into a curved shape (R-processability, reverse 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 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 film has appropriate flexibility, resulting 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.

[0053] In the above manufacturing method, 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 15 to 17, preparing a roll from which a half-folded film has been wound in advance 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 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 it has been folded in the process; and cutting the strip-shaped non-breathable film-like protective material in advance to the length of the straight or curved outer edge of a pair of base fabric panels, folding it 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 fixed. Furthermore, by continuously feeding the film from the roll, the folded portion of the film is less likely to shift, and the warping of the folded film is suppressed (because the film structure becomes symmetrical from top to bottom), which can lead to further benefits such as reduced wrinkle formation (improved quality).

[0054] 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. Furthermore, as shown in Figure 17, for example, the base fabric can be sandwiched between upper and lower conveyor belts at the welding point, and continuous welding can be performed by applying heat while the base fabric is transported by the conveyor belts and sandwiched between upper and lower heating plates. 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, allowing 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 welding by 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 17, a cooling section using a cooling plate may be provided immediately after welding. Providing a cooling section improves the adhesion of the non-air-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.

[0055] 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.

[0056] 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).

[0057] [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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] [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 11, using tension application and clamping methods, it is necessary to manufacture the folded strip of film so that neither the beginning nor the end is open. Therefore, the following two methods can be employed. One method, as shown in Figure 12, 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 13. The second method, as shown in Figure 14, 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 14), 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 14, 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 13 and 14, in the isolated sewing section, there are areas where the folded, non-breathable protective material overlaps, but in these overlapping areas, there may be regions where the non-breathable protective material is not bonded to itself. This structure can be used as a method for intentionally providing a joint section of a folded, non-breathable protective material when welding a half-folded, non-breathable protective material near a sewing shape with branching points or a bent sewing shape, or when the airbag size is large and the process is divided for ease of work, etc. Furthermore, it can be widely applied to methods such as the 2-step method or the 2-piece bonding method, regardless of whether tension is applied or the clamping method is used. [Examples]

[0062] 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.

[0063] [Laminated base fabric multilayer film] The film is a three-layer multilayer film consisting of an adhesive layer, an intermediate layer, and an outer layer. PA6 / 12 was used for the adhesive layer, m-PE for the intermediate layer, and PA6 / 66 for the outer layer. The film was extruded from a multilayer circular die and obtained by inflation to obtain a three-layer film with a thickness of 20 μm. The side to be laminated to the plain weave base fabric was the side with the adhesive layer.

[0064] [Laminated PA base fabric (LamiPA)] As the laminated PA base fabric used for the base fabric panel, a plain weave fabric woven using nylon 66 multifilament fibers for both the warp and weft was used. The multilayer film and the base fabric were layered together and bonded using a laminator (see Figure 9) so that the multilayer film was in contact with the silicone rubber roll. The lamination conditions at this time were as follows: Temperature: 160℃ Roll speed: 0.3 m / min Linear pressure: 2.3kg / cm. The resulting base fabric had a total fineness of 470 dtex, 136 filaments, and a weave density of 49 threads / inch (2.54 cm).

[0065] [(Si) coated (base) fabric, unlaminated PA or PET base fabric used in the examples] As the Si-coated fabric used as the base fabric panel and / or protective material, a plain weave fabric woven using nylon 66 or polyester multifilament fibers for the 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.

[0066] [Production of the film itself] [How to make the film] The protective film was prepared as follows. As illustrated in Figure 8, 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 1b of the tubular film was formed as the adhesive layer, and the outer surface 1a as the outer layer. The film formation conditions were as follows. Die temperature setting: 210℃ (230℃ for multilayer films using resin E) Circular Dye: Lip outer diameter = 95mm, Lip clearance = 3mm Blow-up ratio: 1.1 times Air ring temperature: 22℃ Distance between circular die and pinch roll: 2.4m Pickup speed: 12m / min

[0067] [Film raw materials] (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) Polya Mido 6 / 12 copolymer (Tg=47℃, Tm=128℃, SP value=13.6 (cal / cm²) 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) PET: Polyethylene terephthalate film 38μm "Product name: Lumirror #38 S10 (Toray Industries, Inc.)" (SP value = 10.7 (cal / cm) 3 ) 1 / 2 ), HSP value = 21.8 (cal / cm³) 3 ) 1 / 2 ) (Resin E) PO: Product name "Admer NF528" (manufactured by Mitsui Chemicals) Acid-modified polyethylene (Tm=120℃) (Resin F) PA6: Product name "Ube Nylon 1022B" (manufactured by Ube Industries) Polyamide 6 (Tg=44℃, Tm=221℃, SP value=12.7 (cal / cm) 3 ) 1 / 2 HSP value = 22.2 (cal / cm³) 3 ) 1 / 2 ) (Resin G) TPEE-1: Thermoplastic polyether ester elastomer, product name "Hytrel 7277" (manufactured by Toray DuPont Co., Ltd.) (Tg=14℃, Tm=216℃, Melt Index =1.5 (240℃)) (Resin H) PA12 Elastomer: Product name "UBESTA XPA 9063F1" (manufactured by Ube Industries) Thermoplastic polyamide elastomer (Tg=22℃, Tm=176℃) (Resin I) TPEE-2: Thermoplastic polyether elastomer. Product name: "Tifablock A1700N" (manufactured by Mitsubishi Chemical) (Tg=-46℃, Tm=153℃) (Resin J) TPEE-3: Thermoplastic polyester elastomer, product name "Hytrel 5577" (manufactured by Toray DuPont Co., Ltd.) (Tg=-20℃, Tm=208℃)

[0068] The film configurations used in Examples 1-11 and Comparative Examples 1-6 are shown in Tables 1 and 2 below.

[0069] (Tensile modulus of film) 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 when a strip-shaped non-permeable, breathable film-like protective material is unfolded from a half-folded state and pulled. If the length of the measurement sample is short and the aforementioned 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.

[0070] (Tensile elongation of the 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, if the length of the sample taken for measurement is short and the distance between chucks cannot be met, the distance between chucks may be narrowed. In this case, a tensile speed that results in a strain rate of 100% / min should be selected.

[0071] (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. (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

[0072] [Silicone adhesive] For bonding the protective material to the main panel at the seams, we used TCS 7770XL / C adhesive manufactured by Elchem ​​Japan Co., Ltd. The cartridges were Mixpack cartridges with a capacity of 200cc:200cc. These were loaded into a manual gun DM400-01 manufactured by Tomita Engineering Co., Ltd., and dispensed using a static mixer MC13-12.

[0073] [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.

[0074] [sewing machine] JUKI Corporation's LU-2210W-7 was used for sewing each component of the airbag.

[0075] [Thermal welding 1] For welding the protective material to the main panel, a continuous-feed type small hot plate device LHP-PP1 (welding machine (belt heat compression machine)) 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 17, 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.

[0076] [Thermal welding 2] For welding the protective material to the main panel, a continuous feed type small heating plate device LHP-PP1 manufactured by Quinlight Electronics Co., Ltd. was used. The upper heater temperature was set to 160°C, the lower heater temperature to 140°C, and the feed speed to 0.1 m / min, and the device was applied to sandwich the main panel from above and below.

[0077] [Ultrasonic welding] Ultrasonic welding of the protective material and the main panel was performed using a small ultrasonic welding machine "AUH30CW" manufactured by Suzuki Motor Corporation (horn: tip Φ3.8-Φ7.5×L(41)mm).

[0078] [Preparation of protective material] Two pieces of film cut to the shape shown in Figure 10 were used for each condition. The outer layers of the films were overlapped so that they faced inward, and the two pieces were bonded together along the inner edge with a cyanoacrylate-based instant adhesive (manufactured by Konishi) with a width of 5 mm, so that the length from the outer edge was the predetermined length, and then allowed to dry completely. Furthermore, for the PE-PA film, a 10mm wide PE layer was peeled off from the inner edge of the film, and the PA resins were bonded together. The PE-PET film was created by peeling off a 10mm wide PE layer from the inner edge of the film and bonding the PET resins together.

[0079] [Fabrication of the main (base fabric) panel] Two pieces of base fabric, cut to the shape shown in Figure 1, were layered together to form the main inflatable section (bag-like) of the airbag. After inserting the protective material described later, and / or applying or welding adhesive, the outer perimeter was sewn with the aforementioned sewing thread using the aforementioned sewing machine at a rate of 50 stitches per 10 cm, with a seam allowance of 10 mm. Three backstitches were added at the beginning and end of the sewing.

[0080] [Inner tube fabrication] Two pieces of the Si-coated fabric, cut to the shape shown in Figure 1, were used as inner tubes to be inserted inside the gas inlet of the airbag. The coated surfaces were placed on top of each other with the coated surfaces facing inward, and both ends were sewn together using the sewing machine with the sewing thread at a rate of 50 stitches per 10 cm, leaving a seam allowance of 10 mm. Three backstitches were made at the beginning and end of the sewing.

[0081] (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. Furthermore, after aging the main panels sewn according to the specifications described below for 400 hours in an environment of 105°C, the change in internal pressure of the airbags over time was measured. The test was performed once for each of the three airbags, and the average of the results of the three measurements was calculated as the internal pressure retention rate 6 seconds after aging, expressed as a percentage.

[0082] (2) Thickness of the seam after folding (mm) The straight seam 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, and the value was recorded when pressed with a force of 300gf. 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.

[0083] (3) Tackiness after aging 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. A 30mm x 30mm folded sample was created by folding the cut sample piece in half perpendicular to the straight seam. A weight of 300g and 30mm x 30mm was placed on it, and it was left to stand (age) for 400 hours in an environment of 105℃. After that, the seam line was pulled out from the unfolded sample to create an evaluation sample piece. When a pair of base fabric panels were grasped and pulled perpendicular to the seam line, those that maintained the loop structure were designated as "A", and those in which the film tore or the adhesive surface between the film and the base fabric panel peeled off were designated as "B".

[0084] [Examples 1-3] Unlaminated PA base fabric was used as the main panel. The protective material used was a two-layer multilayer film consisting of an adhesive layer and an outer layer. As illustrated in Figure 8, PA6 / 12 was used for the adhesive layer and PE (LDPE) for the outer layer. These were extruded from a multilayer circular die and obtained by inflation to produce two-layer films with thicknesses of 20, 30, and 40 μm. As the bag-shaped inflation section (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked with the uncoated sides facing inward, and the protective material was inserted inside. The protective material and the main panel were welded together using the heat welding method 1. The outer periphery was sewn with sewing thread according to the method for manufacturing the main (base fabric) panel described above. The evaluation results of the airbag using this film are shown in Table 1 below.

[0085] [Example 4] The airbag was fabricated in the same manner as in Example 2, except that ultrasonic welding was performed instead of heat welding 1. The evaluation results of the obtained airbag are shown in Table 1 below.

[0086] [Example 5] Unlaminated PET base fabric was used as the main panel. The protective material used was a two-layer multilayer film consisting of an adhesive layer and an outer layer, with PE (LDPE) used for the outer layer and PET for the adhesive layer. A single-layer film with a thickness of 7 μm was obtained by extruding PE (LDPE) from a multilayer circular die and using the inflation method. A two-layer multilayer film consisting of two types was prepared by heat laminating the aforementioned 7 μm PE single-layer film onto a commercially available 38 μm PET film (Toray Industries, Inc., Lumirror #38-S10). As the bag-shaped inflation section (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked with the uncoated sides facing inward, and the protective material was inserted in between. The protective material and the main panel were welded together using ultrasonic welding. The outer perimeter was sewn with sewing thread using the method described above for preparing the main (base fabric) panel. The evaluation results of the airbag using this film are shown in Table 1 below.

[0087] [Example 6] Laminated PA base fabric was used as the main panel. The protective material used was a multilayer film with four layers of four types, consisting of an adhesive layer, intermediate layer 1, intermediate layer 2, and outer layer. As illustrated in Figure 8, PA6 / 12 was used for the adhesive layer, PO for intermediate layer 1, PA6 / 66 for intermediate layer 2, and PE (LDPE) for the outer layer. The film was extruded from a multilayer circular die and an inflation method was used to obtain a 30 μm thick, four-layer film of four types. As the bag-shaped inflation section (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked with the laminated side facing inward, and the protective material was inserted inside. The protective material and the main panel were welded together using the heat welding method 1. The outer periphery was sewn with sewing thread according to the method for manufacturing the main (base fabric) panel described above. The evaluation results of the airbag using this film are shown in Table 1 below.

[0088] [Example 7] The main panel used was made of laminated PA base fabric. The protective material used was a three-layer multilayer film consisting of an adhesive layer, an intermediate layer, and an outer layer. Here, PA6 / 12 was used for the adhesive layer, PO for the intermediate layer, and PA6 for the outer layer. It was extruded from a multilayer circular die and an inflation method was used to obtain a three-layer film with a thickness of 20 μm. As the bag-shaped inflation part (main panel) of the airbag, the base fabric was cut into the shape shown in Figure 1, and two pieces were stacked with the laminated side facing inward, with the protective material inserted in between. The protective material and the main panel were welded together using the heat welding method 1. The outer edge was sewn with sewing thread using the method for making the main (base fabric) panel described above. The evaluation results of the airbag using this film are shown in Table 2 below.

[0089] [Example 8] The main panel used was made of unlaminated PA base fabric. The protective material used was a two-layer multilayer film consisting of an adhesive layer and an outer layer. Here, PA6 / 12 was used for the adhesive layer and TPEE-1 for the outer layer. It was extruded from a multilayer circular die and an inflation method was used to obtain a two-layer film with a thickness of 20 μm. As the bag-shaped inflation part (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked with the uncoated side facing inward, and the protective material was inserted in between. The protective material and the main panel were welded together using the heat welding method 1. The outer edge was sewn with sewing thread using the method described above for making the main (base fabric) panel. The evaluation results of the airbag using this film are shown in Table 2 below.

[0090] [Example 9] The main panel used was made of laminated PA base fabric. The protective material used was a three-layer multilayer film consisting of an adhesive layer, an intermediate layer, and an outer layer. PA6 / 12 was used for the adhesive layer, PO for the intermediate layer, and TPEE-1 for the outer layer. The film was extruded from a multilayer circular die and subjected to inflation to obtain a three-layer film with a thickness of 30 μm. As the bag-shaped inflation section (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked with the laminated side facing inward, and the protective material was inserted in between. The protective material and the main panel were welded together using the heat welding method 1. The outer perimeter was sewn with sewing thread using the method described above for manufacturing the main (base fabric) panel. The evaluation results of the airbag using this film are shown in Table 2 below.

[0091] [Example 10] The main panel used was made of laminated PA base fabric. The protective material used was a three-layer multilayer film consisting of an adhesive layer, an intermediate layer, and an outer layer. PA6 / 12 was used for the adhesive layer, PO for the intermediate layer, and PA6 / 66 for the outer layer. The film was extruded from a multilayer circular die and subjected to inflation to obtain a three-layer film with a thickness of 30 μm. As the bag-shaped inflation section (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked together, and the protective material was inserted in between. The protective material and the main panel were welded together using the heat welding method 2. The outer perimeter was sewn with sewing thread using the method described above for manufacturing the main (base fabric) panel. The evaluation results of the airbag using this film are shown in Table 2 below.

[0092] [Example 11] The main panel used was made of unlaminated PET base fabric. The protective material used was a two-layer multilayer film consisting of an adhesive layer and an outer layer. Here, TPEE-2 was used for the adhesive layer and TPEE-3 for the outer layer. The film was extruded from a multilayer circular die and an inflation method was used to obtain a two-layer film with a thickness of 20 μm. As the bag-shaped inflation part (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked with the uncoated sides facing inward, and the protective material was inserted in between. The protective material and the main panel were welded together using the heat welding method 1. The outer periphery was sewn with sewing thread using the method described above for making the main (base fabric) panel. The evaluation results of the airbag using this film are shown in Table 2 below.

[0093] [Comparative Example 1] The main panel used was made of unlaminated PA base fabric. The protective material used was a single-layer film, extruded from a multilayer circular die using PA6 / 12 and obtained a single-layer film with a thickness of 30 μm by inflation method. As the bag-shaped inflation part (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked together, with the uncoated side facing inward and the protective material inserted inside. The protective material and the main panel were welded together using the heat welding method 1. The outer edge was sewn with sewing thread using the method described above for making the main (base fabric) panel. The evaluation results of the airbag using this film are shown in Table 1 below.

[0094] [Comparative Example 2] The main panel used was made of unlaminated PA base fabric. The protective material used was a two-layer multilayer film consisting of an adhesive layer and an outer layer. PA6 / 66 was used for the adhesive layer and PA6 for the outer layer. The film was extruded from a multilayer circular die and an inflation method was used to obtain a 30 μm thick multilayer film. As the bag-shaped inflation section (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked together, with the uncoated side facing inward and the protective material inserted inside. The protective material and the main panel were welded together using ultrasonic welding. The outer perimeter was sewn with sewing thread using the method described above for making the main (base fabric) panel. The evaluation results of the airbag using this film are shown in Table 1 below.

[0095] [Comparative Example 3] The main panel used was made of unlaminated PA base fabric. For the airbag's inflatable bag (main panel), two pieces of base fabric, cut to the shape shown in Figure 1, were layered with the coated side facing inward. No protective material was inserted. The outer perimeter was then sewn with sewing thread. The evaluation results of this airbag are shown in Table 1 below.

[0096] [Comparative Example 4] The main panel used was made of unlaminated PA base fabric. For the airbag's inflatable bag (main panel), the base fabric was cut into the shape shown in Figure 1. Silicone adhesive was applied to the seams, and two pieces were layered with the coated side facing inward. No protective material was inserted. The outer perimeter was then sewn with sewing thread. The evaluation results of this airbag are shown in Table 1 below.

[0097] [Comparative Example 5] The main panel used was made of laminated PA base fabric. The protective material used was a three-layer multilayer film consisting of an adhesive layer, an intermediate layer, and an outer layer. PA6 / 12 was used for the adhesive layer, PO for the intermediate layer, and PA12 elastomer for the outer layer. The film was extruded from a multilayer circular die and subjected to inflation to obtain a 40 μm thick three-layer film. As the bag-shaped inflation section (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked with the uncoated sides facing inward, and the protective material was inserted inside. The protective material and the main panel were welded together using the heat welding method 2. The outer perimeter was sewn with sewing thread using the method described above for manufacturing the main (base fabric) panel. The evaluation results of the airbag using this film are shown in Table 2 below.

[0098] [Comparative Example 6] The main panel used was made of laminated PA base fabric. A protective material was welded to the laminated surface. The protective material used was a single-layer film, and a single-layer film with a thickness of 40 μm was obtained by extruding PA6 / 12 from a multilayer circular die and using the inflation method. As the bag-shaped inflation part (main panel) of the airbag, two pieces of base fabric cut to the shape shown in Figure 1 were stacked with the uncoated side facing inward, and the protective material was inserted in between. The protective material and the main panel were welded using the heat welding method 2. The outer edge was sewn with sewing thread using the method for making the main (base fabric) panel described above. The evaluation results of the airbag using this film are shown in Table 2 below.

[0099] [Table 1]

[0100] [Table 2]

[0101] In Examples 1 to 11, a laminated resin film was used as the folded, non-breathable film-like protective material, and the difference between the SP value of the resin constituting the first surface layer and the SP value of the resin constituting the second surface layer was set to 2.0 [cal / cm²].3 ) 1 / 2 By setting the temperature to 50°C or higher, or by setting the melting point difference to 50°C or higher, as shown in Figure 6, the second surface layer peeled off when the airbag deployed, and there was no welding of the loops, resulting in a high airbag internal pressure retention rate, and because silicone adhesive was not used in the seams, compactness was also good.

[0102] In Comparative Example 1, a single-layer film was used, which caused the loops to fuse together, resulting in a deterioration of the airbag's internal pressure retention rate. In Comparative Example 2, the difference in SP values ​​was less than 2.0, causing the loops to weld together and worsening the airbag's internal pressure retention rate. In Comparative Example 3, the airbag's internal pressure retention rate deteriorated because a folded, non-breathable film-like protective material was not used. In Comparative Example 4, a silicone adhesive was used instead of a folded, non-breathable film-like protective material, resulting in a deterioration of compactness. In Comparative Example 5, although a multilayer film was used, the melting point difference was less than 50°C, causing the loops to fuse together and resulting in poor airbag internal pressure retention. In Comparative Example 6, a single-layer film was used, which caused the loops to fuse together, resulting in a deterioration of the airbag's internal pressure retention rate. [Industrial applicability]

[0103] The airbag and its manufacturing method according to the present invention are characterized in that the outer surfaces of both ends of a folded, non-breathable protective material are bonded 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, thereby providing an airbag with high internal pressure retention performance and excellent compactness, as well as a highly productive manufacturing method for the airbag. 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. [Explanation of symbols]

[0104] 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. In an airbag in which at least one pair of base fabric panels are sewn together at their outer edges, An airbag wherein the outer surfaces of both ends of a folded strip-shaped non-breathable film-like protective material are bonded to the inner surface of each of the pair of base fabric panels in a predetermined width adhesive region along the suture, having 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 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 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.

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

3. The airbag according to claim 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 60°C to 160°C lower than the melting point of the resin constituting the second surface layer.

4. 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 The airbag according to claim 1, which is as described above.

5. 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 HSP value between any adjacent layers is 1.0 [cal / cm²]. ３ ) １／２ The airbag according to claim 1, which is as described above.

6. The airbag according to claim 2 or 3, wherein the glass transition temperature (Tg) of the resin constituting the second surface layer is 0°C or higher.

7. The airbag according to claim 1, 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.

8. The airbag according to claim 1, wherein the thickness of the non-breathable protective material is 0.001 mm or more and 0.5 mm or less.

9. The airbag according to claim 1, wherein the tensile modulus of the folded, non-breathable strip-shaped protective material is 100 to 800 MPa.

10. The airbag according to claim 1, wherein the adhesive strength in the adhesive region is 1 N / cm or more.

11. The airbag according to claim 1, wherein the airbag has an R portion with a radius of curvature of 300 mm or less in the adhesive region.

12. The airbag according to claim 1, wherein the airbag has an inverted R portion with a radius of curvature of 300 mm or less in the adhesive region.

13. The airbag according to claim 11, wherein the surface step of the R portion is 400 μm or less.

14. The airbag according to claim 11, wherein the ratio (R portion / straight portion) of the surface step (peak-valley difference) of the R portion to the surface step (peak-valley difference) of the substantially straight portion excluding the R portion is 0.6 to 2.

0.

15. The airbag according to claim 11, wherein the adhesive strength in the R portion is 1 N / cm or more.

16. The airbag according to claim 11, wherein the ratio of the adhesive strength in the R portion to the adhesive strength of the substantially straight portion excluding the R portion (R portion / substantially straight portion) is 0.5 to 2.

5.

17. The airbag according to claim 1, wherein the airbag includes an isolated sewn portion forming a closed space.

18. The airbag according to claim 17, wherein in the isolated sewing portion, there is a portion where the folded strip-shaped non-breathable protective material overlaps.

19. The airbag according to claim 18, wherein, at the point where the folded strip-shaped non-breathable protective material overlaps, there exists a region where the non-breathable protective material is not bonded to itself.

20. 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 step of inserting a non-breathable film-like protective material, which is a folded strip or a shape conforming to the shape of the base fabric panel, made of a laminated resin film of a predetermined width and consisting of two or more layers including a first surface layer and a second surface layer, between the inner surfaces of each of the pair of base fabric panels along the outer edge of the pair of base fabric panels; A welding process in which heat or ultrasonic waves are applied from the outside of the pair of base fabric panels to weld the first surface layer to the inner surface of the base fabric panels, wherein the second surface layers are not welded to each other, or are welded to each other 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; A suturing step of sewing the pair of base fabric panels together in the vicinity of the resulting welded area before, after, or simultaneously with the aforementioned welding; The manufacturing method, including the above.

21. The method according to claim 20, 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.

22. 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 The method according to claim 20, which is as described above.

23. 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 HSP value between any adjacent layers is 1.0 [cal / cm²]. ３ ) １／２ The method according to claim 20, which is as described above.

24. The method according to claim 20, wherein, when a tensile force is applied between the pair of base fabric panels during the deployment of the airbag, the distance between the distal ends along the folded non-breathable film-like protective material is greater than or equal to the distance between the distal ends along the pair of base fabric panels.

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