Elastic member and disposable wearing article including elastic member

An underpants-type disposable wearing article comprising:

• an outer member that is formed in an integrated state from a front body to a back body or that is formed separately for the front body and the back body,
• an inner member attached to an intermediate portion in the inside of the outer member in a width direction and formed by interposing an absorbent body between a liquid pervious top sheet and a liquid impervious sheet to extend to both front and back sides of a crotch portion,
• side seal portions in which both side portions of the outer member in the front body and both side portions of the outer member in the back body are bonded to each other, and
• a waist opening and a pair of right and left leg openings,
• wherein the outer member comprises an elastic film being a thermoplastic resin film having elasticity in itself and interposed between a first sheet layer having air permeability and a second sheet layer having air permeability,
• wherein the first sheet layer and the second sheet layer comprise an elastic sheet stretchable structure bonded through joint holes penetrating the elastic film at a plurality of sheet joined portions arranged at intervals,
• wherein the elastic sheet stretchable structure extends beyond end portions of the inner member in a front-back direction but does not extend up to waist end portions,
• wherein the outer member in at least one of the front body and the back body is provided with elongated waist portion elastic members over a range in the width direction corresponding to a space between the side seal portions in the waist end portions so that a stretchable direction thereof corresponds to the width direction,
• wherein the elastic sheet stretchable structure is allowed to be stretched and contracted in a stretchable direction by a stretching force of the elastic film,
• the joined portions are arranged at intervals along an alignment direction intersecting the stretchable direction to form at least a first joined portion row, a second joined portion row, and a third joined portion row, wherein shapes of the joined portions in a natural length state are elongated in the alignment direction,
• the third joined portion row is formed between the first joined portion row and the second joined portion row in the stretchable direction,
• an interval in the alignment direction between the joined portions of at least a part of the third joined portion row is longer than intervals in the alignment direction between the joined portions of the first joined portion row and the second joined portion row,
• the joined portions of the third joined portion row form an intersection row with joined portions of the first joined portion row and/or joined portions of the second joined portion row adjacent to each other,
• the intersection row extends across the first joined portion row, the second joined portion row, and the third joined portion row along a direction intersecting the alignment direction, and
• a plurality of contraction wrinkles in the first sheet layer and the second sheet layer are formed due to the stretching force of the elastic film, wherein each of the plurality of contraction wrinkles is positioned between adjacent joined portions of the third joined portion row in the alignment direction and between joined portions of the first joined portion row and the second joined portion row in the direction intersecting the alignment direction.