Keita Mizobuchi, Ehime, Japan; Nobuyuki Okada, Ehime, Japan; Ryoichi Ochi, Ehime, Japan; and Terumasa Kamioka, Ehime, Japan.
Assigned to Daio Paper Corporation, Ehime, Japan.

Filed: 1/17/13
Issued: 2/20/18

An underpants-type disposable diaper, in which a front body part and a back body part are each weld-jointed together on both sides to form side seal sections, thereby forming a waist opening and a right-left pair of leg openings, wherein: at least an outer surface of the side seal section is formed of a nonwoven fabric; the side seal section is formed in a dot pattern in which a plurality of rows of dot-shaped welded parts, disposed with intervals in a vertical direction, are disposed in a transverse direction, and non-welded parts, disposed all over in the transverse direction, are disposed on both sides of each welded part in the vertical direction; the side seal section is set to have a non-densely welded region closer to the waist opening than a densely welded region the non-densely welded region being vertically separated from the densely welded region; and each welded part in the densely welded region is at least partly larger in area than each welded part in the non-densely welded region; the side seal section has a polypropylene region where only nonwoven fabrics of polypropylene or a copolymer thereof are laminated and a non-polypropylene region; the non-polypropylene region having first, second and third regions, the first region being immediately below the polypropylene region, the second region being immediately below the first region and the third region being immediately below the second region; the first region having a first number of nonwoven fabrics laminated, the second region having a second number, which is smaller than the first number, of nonwoven fabrics laminated, and the third region having a third number, smaller than the second number, of non-woven fabrics laminated; whereby the front body part is more easily separated from the back body at the waist opening.