Sadanao Manabe, Tokyo, Japan; Tomotsugu Matsui, Ehime, Japan; Akinori Fukae, Tokyo, Japan; and Kosuke Murai, Ehime, Japan.
Assigned to Daio Paper Corporation, Ehime, Japan.

Filed: 10/16/15
Issued: 3/31/20

An underpants-type disposable diaper, comprising: an outer body that forms individually or integrally a front body and a back body; an inner body that has an absorber and is attached to an inner surface of the outer body extending from the front body to the back body through a crotch portion; and leg gathers, having standing parts configured to extend toward the legs of a wearer in a standing state, that extend along both sides of an absorption surface of the inner body of the absorption surface in a width direction, the outer body being joined together at both side edges at the front body and the back body to form a waist opening and a pair of right and left leg openings, wherein the leg gathers have: an inside nonwoven fabric layer constituting an inner surface in the width direction in the standing state; an outside nonwoven fabric layer constituting an outer surface in the width direction in the standing state; elastically stretchable gather members that are provided along a front-back direction between the inside nonwoven fabric layer and the outside nonwoven fabric layer at least forward end portions of the leg gathers in intermediate portions of the leg gathers in the front-back direction; and a liquid impervious film that is sandwiched between the inside nonwoven fabric layer and the outside nonwoven fabric layer in an area ranging from a base end-side to a forward end-side thereof, wherein parts of the leg gathers that are provided with the liquid impervious film and that is closer to the base end-side than the forward end-side constitute nonwoven fabric absent parts where the inside nonwoven fabric layer does not exist and the liquid impervious film is exposed through the entire leg gathers in the front-back direction, the underpants-type disposable diaper further comprises: a liquid pervious top sheet provided on a front surface side of the absorber and on the inner surface of the standing parts of the leg gathers, the liquid pervious top sheet being formed of nonwoven fabric extending to the base end-side of the standing parts of the leg gathers beyond both sides of the absorber in the width direction, extended parts of the liquid pervious top sheet extending via the base end of the standing parts of the leg gathers and forming a part of the inner surface of the standing parts of the leg gathers, a gather sheet provided on a back surface side of the inner body, the gather sheet being formed of nonwoven fabric extending beyond the liquid pervious top sheet on both sides of the absorber in the width direction, wherein both end portions of the gather sheet in the width direction are folded to form folded portions, and forward ends of the folded portions are separated from the extended parts of the liquid pervious top sheet, the liquid impervious film is provided at least from a portion between the folded portions of the gather sheet to a portion between the liquid pervious top sheet and the gather sheet, and the outside nonwoven fabric layer is formed by a portion of the gather sheet other than the folded portion, the inside nonwoven fabric layer is formed by the folded portions of the gather sheet and the extended parts of the liquid pervious top sheet, and the nonwoven fabric absent parts are formed as a separated area between the folded portions of the gather sheet and the extended parts of the liquid pervious top sheet.