Abstract: An improved joining structure for a waterproof fabric composed of a base fabric with a soft (elastomeric) resin film adhered thereon is provided. The joining structure is formed in a welt seam in which a hot-melt resin adhesive layer is interposed as a part of intermediate layers of the structure. The joining structure has properties of (1) bond strength .gtoreq.25 kg/25 cm width, (2) bending stiffness .ltoreq.20 gf.multidot.cm.sup.2 /cm and (3) water resistance after rubbing 1,000 times according to Scott shape method .gtoreq.800 mm H.sub.2 O.The joining structure can be formed by a method including joining the waterproof fabrics to form a welt seam with a hot melt resin layer put between and following that applying a high-frequency welding to the welt seam portion at a condition with an insulating elastic sheet interposed between the welt seam portion and electrode means to cause the hot-melt resin to be melted.

Abstract: A hollow weave air bag, a configuration of a boundary line between a hollow portion (6) and a peripheral portion (4) of a single layer weave bonding band of which is a curve obtained by that an optional point on an equation L=R(1+P/2.times.cos 4.theta.) draws by changing an angle .theta., wherein:L stands for a length of a straight line between a center (c) of a hollow portion (6) and the boundary line (7);.theta. stands for an angle (radian) formed between a warp axis of a woven fabric and a straight line connecting an optional point (A) on the boundary line to a center (C) of the hollow portion (6);R stands for a mean value of a radius of a circumscribed circle and a radius of a inscribed circle;P stands for a ratio of a difference between the radius of the circumscribed circle and the radius of the inscribed circle against the mean radius R;O<P.ltoreq.0.