US Patent No.: 8,287,511 B2
Inventor(s): Koichiro Mitsui, Kagawa-ken, Japan; Hironao Minato, Kagawa-ken, Japan); and Yasushi Sayama, Kagawa-ken, Japan.
Company: Uni-Charm Corporation, Ehime, Japan.
Filed: 5/26/04
Issued: 10/16/12

A disposable diaper, comprising: a front waist region, a rear waist region and a crotch region extending in a longitudinal direction of said diaper between said front and rear waist regions; a body fluid absorbent core extending over said crotch region and into said front and rear waist regions, said absorbent core having opposite front and rear ends located in the front and rear waist regions, respectively; front side flaps defining transversely opposite side edges of said front waist region, respectively; rear side flaps defining transversely opposite side edges of said rear waist region, respectively; a front waist elastic contractibly attached to the front waist region along a front end edge thereof; a rear waist elastic contractibly attached to the rear waist region along a rear end edge thereof; and a pair of fasteners for releasably connecting said front and rear waist regions with each other, said fasteners being attached to the rear side flaps, respectively; wherein each of said front side flaps comprises: a first fibrous nonwoven fabric adapted to face away from a wearer when the diaper is worn on the wearer; and a second fibrous nonwoven fabric laminated on said first fibrous nonwoven fabric and being adapted to face toward and directly contact the wearer when the diaper is worn on the wearer, wherein said first fibrous nonwoven fabric has a kinetic friction coefficient higher than a kinetic friction coefficient of said second fibrous nonwoven fabric, and wherein the kinetic friction coefficient of said first fibrous nonwoven fabric is in a range of 1.05 to 2.11 as measured in a transverse direction of said diaper and the kinetic friction coefficient of said second fibrous nonwoven fabric is in a range of 0.35 to 0.60 as measured in the transverse direction; wherein each of said rear side flaps is formed from a stretchy sheet which is elastically stretchable in both the longitudinal direction and the transverse direction or at least in the transverse direction; wherein, when the fasteners releasably engage the front waist region to attach the front and rear waist regions together when the diaper is worn on the wearer, the stretchy sheet of each of the rear side flaps overlaps and directly contacts the first fibrous nonwoven fabric of the respective front side flap; wherein said waist elastics have a tensile stress, as measured in the transverse direction, lower than a tensile stress of said rear side flaps, as measured in the transverse direction; and wherein each of said front side flaps further comprises a plurality of heat-sealing spots which are distributed substantially at regular intervals and at which said first and second fibrous nonwoven fabrics are bonded together to define a composite non-woven fabric.