Mina Takaishi, Tochigi, Japan.
Assigned to Daio Paper Corporation, Ehime, Japan.

Filed: 5/24/19
Issued: 1/28/25

An underpants-type disposable diaper comprising: an integral outer body extending over a front body and a back body or an outer body separately provided to the front body and the back body; side seal portions obtained by bonding both side portions of the outer body in the front body and both side portions of the outer body in the back body, respectively; a waist opening and a pair of right and left leg openings; a front lower torso region of the outer body in the front body, determined as a front-back direction region having the side seal portions; a back lower torso region of the outer body in the back body, determined as a front-back direction region having the side seal portions; an inner body attached to an intermediate portion in a width direction of the outer body, the inner body extending from the front lower torso region to the back lower torso region; an absorber contained in the inner body, the absorber extending from the front lower torso region to the back lower torso region; a stretchable region contracted in the width direction on a waist side of a back end portion of the absorber in the back lower torso region, the stretchable region extending forward up to a position to overlap the inner body; and a barrier sheet that extends from forward of to backward of a back end of the absorber and extends from both side edges in the width direction of the absorber outward in the width direction, wherein the barrier sheet has a free part not bonded to a member on a back surface side and a fixed part bonded to the member on the back surface side, the free part is located at least in a middle in the width direction of a part of the barrier sheet that overlaps the absorber and is continuous from a front edge to a middle in a front-back direction of the barrier sheet, a back end of the inner body is positioned backward of the back end of the absorber, and a back end of the free part is positioned between the back end of the inner body and the back end of the absorber, the fixed part extends backward from the back end of the free part, the fixed part further surrounds both sides in the width direction of the free part, and a width direction inner edge of a part of the fixed part that is located on both sides in the width direction of the free part is on an outer side of a side edge of the inner body in the width direction and adjacent to the side edge of the inner body or is located on the inner body, a pocket-shaped dorsal side barrier having an inlet opening on a crotch side is formed with the free part of the barrier sheet being raised while a part of the absorber that overlaps the free part of the barrier sheet being curved to bulge outward to prevent back leakage from the underpants-type disposable diaper, a torsion hardness of a predetermined part including the back end portion of the absorber is 0.18 to 0.32 N·cm/cm.