Disposable absorbent article with elastized pleated longitudinal cuffs

Abstract: An absorbent article is provided with a pair of side flaps along transversely opposite side edges of the article. Each of these side flaps is formed on its upper surface with a plurality of pleats extending longitudinally of the side flap. Each of the pleats contains an elastically stretchable/contractile member extending along its distal edge so as to operate longitudinally of the pleat.

Description: This invention relates to disposable absorbent articles and more particularly to such articles such as disposable diapers, sanitary napkins or the like for absorption and containment of body exudates. Absorbent articles of such type are well known and generally comprises a liquid-permeable topsheet, a liquid-impermeable backsheet, a liquid-absorbent core disposed between these two sheets and a pair of elastically stretchable/contractile side flaps being contiguous to and extending along transversely opposite side edges of the core. Disposable diapers is also well known in which the paired side flaps comprise a first pair of elastically stretchable/contractile side flaps extending outward from transversely opposite side edges of the core and a second pair of elastically stretchable/contractile side flaps being contiguous to and extending along transversely opposite side edges of the core. Japanese Patent Application Disclosure (Kokai) No. Hei8-215239 discloses a disposable diaper having the first and second pairs of side flaps, each of the second side flaps being folded in zigzag to form a plurality of pleats between its proximal edge and its distal edge and these pleats contain elastically stretchable/contractile members extending along their apices, respectively. In the case of the well known disposable diaper disclosed in said Japanese Patent Application Disclosure (Kokai) No. Hei8-215239, the second pair of side flaps have the pleats adapted to come elastically in line-contact with the wearer's skin along the apices of the respective pleats. However, a region defined between the apex of the outermost pleat and the distal edge of the second side flap often elastically comes in surface-contact with the wearer's skin. Such surface-contact is certainly effective to prevent leakage of body exudates but may cause skin eruption over a large area. In addition, the pleats are relatively large and the sheet material for the second side flaps must be relatively large. Consequently, a manufacturing cost of diaper is correspondingly increased. Other examples of diapers employing raised side flaps are disclosed in WO 95/02381, WO 96/22755 and US 5,304,159. In view of the above problems, it is a primary object of the invention to provide a disposable absorbent article such as a disposable diaper having paired side flaps adapted to come in line-contact with the wearer's skin along a plurality of lines preferably under an elastic effect and being able more effectively to protect the wearer's skin from eruption than the side flaps of surface-contact fashion can. According to one aspect of the invention, there is provided a disposable absorbent article having a symmetric shape with respect to a longitudinal center line thereof and comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, a liquid-absorbent core disposed therebetween and elastically stretchable/contractile side flaps being continuous to and extending along transversely opposite side edges of the core, wherein the side flaps respectively have first proximal edges, first distal edges, upper surfaces intended to come in contact with the wearer's skin and lower surfaces indicated not to come in contact with the wearer's skin wherein the side flaps are formed on the upper surfaces with a plurality of pleats extending longitudinally of the side flaps and spaced one from another between the first proximal edges and the first distal edges; and the pleats respectively have second proximal edges sharing the upper surfaces as their base and second distal edges normally biased to rise up toward the wearer's skin. According to another aspect of the invention, there is provided disposable absorbent article having a symmetric shape with respect to a longitudinal center line thereof and comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, a liquid-absorbent core disposed therebetween, a pair of elastically stretchable/contractile side flaps extending outward from transversely opposite side edges of the core wherein each of the side flaps has a first proximal edge, a first distal edge, an upper surface intended to come in contact with the wearer's skin and a lower surface intended not to come in contact with the wearer's skin, each of the side flaps being formed on the upper surfaces with plural pleats extending longitudinally of the side flaps and spaced one from another between the first proximal edge and the first distal edge; and each of the pleats has a second proximal edge sharing the upper surface of the side flap as a base thereof and a second distal edge normally biased to rise up toward the wearer's skin. Embodiments of the invention are described below with reference to the accompanying drawings, in which: Fig. 1 is a plan view depicting a partly cutaway disposable absorbent article according to the invention implemented in the form of disposable diaper; and Fig. 2 is a perspective view schematically depicting the diaper in a transverse sectional view. Details of a disposable absorbent article according to the invention will be more fully understood from the description of the disposable diaper as a specific embodiment of the invention given hereunder with reference to the accompanying drawings. Referring to Figs. 1 and 2, a article comprises a liquid-permeable topsheet 1, a liquid-impermeable backsheet 2, a semi-rigid hourglass-shaped liquid-absorbent core 3 disposed between these two sheets 1, 2, a first pair of side flaps 4 each having a high flexibility, and a second pair of side flaps 5 each having a high flexibility and extending between a first proximal edge 5a and a second distal edge 5b. Regarding its configuration, the article is symmetric with respect to a longitudinal center line 20 and composed of front and rear waist regions 6, 7 and a crotch region 8. Each of the first side flaps 4 comprises respective portions 1a, 2a of the topsheet 1 and the backsheet 2 extending outward beyond the associated side edge of the core 3 and a proximal edge 5a of the associated second side flap 5 bonded to the outermost edge of the portion 2a. Portions of the topsheet 1 and the backsheet 2 extending outward beyond peripheral edges of the core 3 are bonded together by means of hot melt adhesive or heat-sealing means (not shown) and define along their transversely opposite side edges a pair of inwardly curved edges 9 intended to surround of the wearer's legs. Portions of the topsheet 1 and the backsheet 2 extending outward beyond longitudinally opposite ends of the core 3 contain therebetween elastically stretchable/ contractile members 10 which extending transversely of the waist regions 7. Portions of the topsheet 1 and the backsheet 2 extending outward beyond transversely opposite side edges of the core 3 contain therebetween elastically stretchable/contractile members 11 which extend along the inwardly curved edges 9. These elastically stretchable/ contractile members 10, 11 are secured under appropriate tensions to the foresaid portions by means of hot melt adhesive (not shown). Each of the second side flaps 5 has an upper surface 5c intended to face the wearer's skin and a lower surface 5d intended to be not in contact with the wearer's skin. On the upper surface 5c of the second flap 5, a plurality of pleats 12 are formed which extend longitudinally of the second side flap 5 and spaced one from another. Each of these pleats 12 has a second proximal edge 12a having the upper surface 5c as its base with the other pleats 12 and a second distal edge 12b normally biased to rise up toward the wearer's skin. The second distal edges 12b of the respective pleats 12 contain elastically stretchable/contractile members 13 extending therein longitudinally of these second distal edges 12b and secured thereto under appropriate tension by means of hot melt adhesive (not shown). While the respective members 13 may have substantially the same stretch stress, it is also possible to adjust so that the stretch stress gradually increases or decreases from the first distal edge 5b to the first proximal edge 5a of the second side flap 5 or so that the stretch stress in the vicinity of the first distal edge 5b is higher or lower than the stretch stress in the vicinity of the first proximal edge 5a. The respective pleats 12 have substantially the same height as measured from their second proximal edges 12a to their second distal edges 12b and a distance between each pair of adjacent second proximal edges 12a is preferably dimensioned to be larger than the height in order to ensure that the respective distal edges 12b should not overlap one another when the respective pleats 12 are collapsed. The height is preferably 2 ∼ 15 mm. While the proximal edges 12a of the respective pleats 12 are illustrated as being in closed state, they may also be in opened state. The respective second side flaps 5 are oriented from the first proximal edges 5a toward the longitudinal center line 20 with their first distal edges 5b lying more close to the longitudinal center line 20 than the first proximal edges 5a. Each of the second side flaps 5 is bonded at longitudinally opposite ends 5e thereof to an upper surface of the topsheet 1 by means of hot melt adhesive or heat-sealing (not shown) with the first distal edge 5b lying on the upper surface of the topsheet 1 in its region overlying the core 3. With such arrangement, first channels 14 adapted to receive body exudates are defined between lower surfaces 5d of the respective second side flaps 5 and the topsheet 1. It is also possible to orient the respective second side flaps 5 inversely with respect to the foresaid orientation, i.e., outwardly of the diaper. In this case, the lower surfaces 5d of the respective second side flaps 5 will face the wearer's skin and the respective pleats 12 will be formed on this surface 5d. The respective pleats 12 will be oriented toward the longitudinal center line 20 so that the second distal edges 12b are more adjacent to the longitudinal center line 20 than the second proximal edges 12a. with such arrangement, second channels 15 adapted to receive body exudates are defined between the upper surfaces 5c and each of pleats 12 although these second channels 15 are smaller than the first channels 14. Even if body exudates discharged on the upper surface of the topsheet 1 between the second pair of side flaps 5 laterally flows, such body exudates are first prevented by the second pair of side flaps 5 from further flowing sideways. Should body exudates overcome such blocking effect and flow on the upper surfaces of the second pair of side flaps 5, such body exudates will be blocked by the plural pleats 12 in multi-stage mode. Accordingly, there is practically no apprehension that body exudates might overflow the second pair of side flaps 5 to the first pair of side flaps 4. Even if a flow of body exudates reach the first pair of side flaps 4 (though there is substantially no possibility), body exudates will be eventually prevented by these first side flaps 4 from leaking outward. As will be apparent from this, it is preferable to provide the first pair of side flaps 4 but not essential to the invention. While the figures depict the diaper of open type in which the front and rear waist regions have their respective transversely opposite side edges 16 left not bonded together, the invention is applicable also to the diaper of shorts or pull-on type in which the side edges are bonded together. Components of the diaper may be made of the materials conventionally employed for components of the disposable absorbent articles such as diapers and sanitary napkins. For example, a hydrophobic or hydrophilic fibrous nonwoven fabric may be employed as material of the topsheet 1 and a moisture-permeable plastic film or such plastic film having its outer surface laminated with a hydrophobic fibrous nonwoven fabric may be employed as material of the backsheet 2. A mixture of fluff pulp and polymer particles of high water absorptivity appropriately compressed may be employed as material for the core 3. The second pair of side flaps 5 may be made of a hydrophobic fibrous nonwoven fabric. The second pair of side flaps 5 are preferably water repellent finished by the well known process to give them a desired waterproof. As will be understood from the foregoing description, the first pair of side flaps 4 are liquid-impermeable and the second pair of side flaps 5 are liquid-resistant. The term "liquid-resistant" used herein should be understood to mean that these side flaps 5 are liquid-permeable under a predetermined or higher pressure but substantially impervious or hardly pervious to body exudates such as urine so long as the diaper is normally worn. The first pair of side flaps 4 may be formed by sheet material other than the topsheet 1 and the backsheet 2 and bonded to the transversely opposite side edges of the core 3 so far as such sheet material is liquid-impermeable. The disposable absorbent article according to the invention includes the side flaps formed with a plurality of pleats adapted to come in line-contact with the wearer's skin along the lines defined by the plurality of pleats preferably under an elastic effect. Therefore, the side flaps according to the invention can prevent leakage of body exudates as effectively as or more effectively than the diaper having the side flaps of surface contact type and can avoid eruption possibly appearing on the wearer's skin more effectively than the side flaps of surface contact type can. The side flaps according to the invention have the plural pleats of which the height may be relatively small and can be formed from correspondingly narrow sheet material. Consequently, an increase in manufacturing cost of the article due to formation of the pleats can be alleviated.

Claims: A disposable absorbent article having a symmetric shape with respect to a longitudinal center line (20) thereof and comprising a liquid-permeable topsheet (4), a liquid-impermeable backsheet (2), a liquid-absorbent core (3) disposed therebetween and elastically stretchable/contractile side flaps (5) being contiguous to and extending along transversely opposite side edges of said core (3), each of said side flaps (5) having a first proximal edge (5a) , a first distal edge (5b), an upper surface (5c) intended to come in contact with the wearer's skin and a lower surface (5d) intended not to come in contact with the wearer's skin, and each of said side flaps being formed on said upper surface (5c) with a pleat (12) extending longitudinally of said side flaps (5) said article being characterized in that : said pleat (12) comprises a plurality of pleats (12) (12) spaced apart one from another between said first proximal edge (5a) and said first distal edge (5b); and each of said pleats (12) (12) has a second proximal edge (12a) sharing said upper surfaces (5c) as a base thereof and a second distal edge (12b) normally biased to rise up toward the wearer's skin. The article according to Claim 1, wherein each of said pleats (12) has an elastically stretchable/contractile member (13) operating along said second distal edge (12b). The article according to Claim 1, wherein each of said pleats (12) is substantially similar one to another so far as a height from said second proximal edge (12a) to said second distal edge (12b) is concerned and a distance between each pair of adjacent second proximal edges (12b) is larger than said height. The article according to Claim 1, wherein each of said side flaps (5) is arranged so that said first distal edge (5b) lies more close to said longitudinal center line (20) than said first proximal edge (5a). The article according to Claim 1, wherein a first channel (14) is defined between said lower surface (5d) of each. of said side flaps (5) and said topsheet (1). The article according to Claim 1, wherein second channels (15) smaller than said first channels (14) are defined between said upper surface (5c) of each of said side flaps (5) and said respective pleats (12). The article according to Claim 1, wherein said side flaps (5) are moisture-permeable and liquid-resistant. A disposable absorbent article having a symmetric shape with respect to a longitudinal center line (20) thereof and comprising a liquid-permeable topsheet (1), a liquid-impermeable backsheet (2), a liquid-absorbent core (3) disposed therebetween, a first pair of elastically stretchable/contractile side flaps (4) extending outward from transversely opposite side edges of said core (3) and a second pair of elastically stretchable/contractile side flaps (5) being contiguous to and extending along transversely opposite side edges of said core (3), each of said second pair of side flaps (5) having a first proximal edge (5a), a first free edge (5b), an upper surface (5c) intended to come in contact with the wearer's skin and a lower surface (5d) intended not to come in contact with the wearer's skin, each of said second pair of side flaps (5) being formed on said upper surface (5c) with a pleat (12) extending longitudinally of said second side flap (5), characterized in that : said pleat (12) comprises a plurality of pleats (12) spaced apart one from another between said first proximal edge (5a) and said first distal edge (5b); and each of said pleats (12) has a second proximal edge (12a) sharing said upper surface (5c) as a base thereof and a second distal edge (12b) normally biased to rise up toward the wearer's skin. The article according to Claim 8, wherein each of said pleats (12) has a elastically stretchable/contractile member operating along said second free edges (12b). The article according to Claim 8, wherein each of said pleats (12) is substantially similar one to another so far as a height from said second proximal edge (12a) to said second distal edge (12b) is concerned and a distance between each pair of adjacent second proximal edges (12b) is larger than said height. The article according to Claim 8, wherein each of said side flaps (15) is arranged so that said first distal edge (5b) lies more close to said longitudinal center line than said first proximal edges (5a). The article according to Claim 8, wherein a first channel (14) is defined between said lower surface (5d) of each of said second pair of side flaps (5) and said topsheet (1). The article according to Claim 8, wherein second channels (15) smaller than said first channels (14) are defined between said upper surface (5c) of each of said second pair of side flaps (5) and said pleats (12), respectively. The article according to Claim 8, wherein said first pair of side flaps (4) are liquid-impermeable. The article according to Claim 8, wherein said second pair of side flaps (5) are moisture-permeable and liquid-resistant. The article according to Claim 8, wherein each of said first pair of side flaps (4) comprises at least a part of said backsheet (2) and a part of each of said second pair of side flaps (5) bonded to an upper surface of said part.

Inventors: KUMASAKA YOSHINORI, KUMASAKA, YOSHINORI, Kumasaka, Yoshinori, c/o Research &amp; Dev. Div.
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 1998
Main classification: A61F13
IPC codes: A61F13, A61F5