Disposable diaper having improved barrier leg cuffs

Abstract: A disposable diaper (1) comprising a pair of cuffs (10) longitudinally extending on the inner surface of said diaper (1) along transversely opposite sides thereof across front and rear sections (6,7) as well as a crotch section (8) longitudinally interposed between these two sections (6,7), wherein each cuff (10) comprises a substantially crescent-shaped elastic sheet and is bonded in its longitudinally stretched state to said inner surface along its longitudinally opposite ends (18) and an outer circular arc (19) defined between these ends (18).

Description: The present invention relates to a disposable diaper. Disposable diapers are well known, in which a pair of cuffs longitudinally extend on the inner surface of the diaper along transversely opposite sides thereof across front and rear sections as well as a crotch section and normally tend to be risen on said inner surface and in order to prevent body fluids from leaking laterally of the diaper. Fig. 4 of the attached drawings is a plan view showing such a known disposable diaper as partially broken away. The diaper 100 has a basic body 105 comprising a liquid-permeable topsheet 102, a liquid-impermeable backsheet 103 and a liquid-absorbent core 104 sandwiched between these two sheets 102, 103 so as to form a front section 106, a rear section 107 and a crotch section 108 interposed between these two sec tions 106, 107 longitudinally of the diaper 100. A pair of water-repellent or liquid-impermeable cuffs 110 longitudinally extend along transversely opposite sides of the basic body 105 across the front and rear sections 106, 107 as well as the crotch section 108 so that these cuffs 110 may bear against the wearer's crotch as the diaper 100 is worn. Additionally, the basic body 105 is provided with elastic members (first elastic members) 116 extending along transversely opposite side edges thereof and bonded in their stretched states to the inner surface of the backsheet 103 for fitting around the respective legs of the wearer. A pair of tape fasteners 113 outwardly extend from transversely opposite side edges of the rear section 107. Each of the cuffs 110 comprises a rectangular strip of sheet having a width W. The cuff 110 has an inner side edge 115 which is a free edge and to which an elastic member (second elastic member) 114 is bonded in its longitudinally stretched state, and an outer side edge 117 extending in parallel to the inner side edge 115. The outer side edge 117 and longitudinally opposite ends 118 of the cuff 110 are bonded, as indicated by oblique lines 120, to the inner surface of the diaper's basic body 105. With such diaper 100 being worn, the cuff 110 is biased under the contraction of the second elastic member 114 to be risen on the topsheet 102 and to form together with the topsheet 102 a pocket (not shown) opening inwardly of the diaper 100. The cuff 110 forms a barrier of the height W against excretion as the cuff 110 is risen substantially in the vertical direction in the crotch section 108. Such diaper 100 is disclosed, for example, in US Patent No. 4,695,278. Slip down of the diaper when worn may often cause a gap to be formed between the diaper and the wearer's crotch, possibly leading to excretion leakage. Certainly it will be possible to avoid such excretion leakage if the cuffs form sufficiently high barriers when they are risen. To achieve this with the above-mentioned known diaper 100, the width W may be dimensioned to be correspondingly large. However, such dimensioning would inevitably result in that the longitudinally opposite ends 118 of the cuffs 110 bonded to the inner surface of the diaper 100 along the waist line become so bulky that comfort to the wearer deteriorates and, in the proximity of the waist line, the relatively wide cuffs 110 disadvantageously cover the topsheet 102 even though the cuffs 110 are properly risen in the crotch section 108. Consequently, the effective area of the topsheet 102 for liquid permeation is unacceptably reduced and thus desired rapid liquid permeation becomes difficult. EP-A-0593082 also discloses a diaper having elasticized cuffs which are formed from the topsheet and backsheet in the region of the side flaps. The elasticised cuffs form an upstanding crescent shape when the diaper is curved inwardly, but they only extend across the crotch section of the diaper and do not also extend substantially across the front and rear sections thereof. It is an object of the invention to solve the above-mentioned problems associated with the cuffs of such known diapers. Accordingly, the invention consists in a disposable diaper comprising a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core sandwiched between these two sheets so as to form a front section, a rear section and a crotch section longitudinally interposed between these two sections, a pair of elasticized side flaps formed by portions of the topsheet and the backsheet extending outwardly of transversely opposite sides of said core, each of said side flaps having an outer side edge, and a pair of elasticized cuffs longitudinally extending on an inner surface of said diaper along transversely opposite sides thereof across the crotch section and normally tending to rise above said inner surface in a crescent shape; characterised in that each cuff is made of an elastic sheet configured substantially in said crescent shape, each cuff extends across the front and rear sections of said diaper as well as across said crotch section, and each cuff has a bonding zone extending outwardly along an arc-shaped outer edge of said cuff, is bonded in a longitudinally stretched state to a portion of said side flap between the side edge of said core and the outer side edge of said side flap at longitudinally opposite ends thereof and along said bonding zone, and covers at least a portion of the area of said side flap extending outwardly from said arc-shaped outer edge. With the disposable diaper arranged as described above, there is no apprehension that the diaper might become bulky around the waist line even when the cuffs are dimensioned to be relatively large, since the cuffs are shaped in crescents, respectively, each having the width progressively reduced toward its longitudinally opposite ends. The invention will now be described by way of example with reference to the accompanying drawings, wherein:- Fig. 1 is a perspective view showing an embodiment of a diaper according to the invention as partially broken away; Fig. 2 is a sectional view taken along a line X - X in Fig. 1; Fig. 3 is a perspective view showing part of a diaper as a variant of the diaper in Fig 1; and Fig. 4 is a plan view showing a known diaper as partially broken away. Referring to Figs. 1 and 2, a diaper 1 comprises a liquid-permeable topsheet 2, a liquid-impermeable backsheet 3 and a liquid-absorbent core 4 sandwiched between these two sheets 2, 3. The top- and backsheets 2, 3 outwardly extend from the periphery of the liquid-absorbent core 4 and are bonded together in these outwardly extending regions to form leg surrounding flaps 11A and a waist surrounding flap 11B. The diaper 1 is longitudinally composed of a front section 6, a rear section 7 and a crotch section 8 interposed between these two sections 6, 7. An elastic member (first elastic member) 12 is bonded in its stretched state to the inner surface of the backsheet 3 circumferentially along the waist surrounding flap 11B of the rear section 7, and a pair of tape fasteners 13 outwardly extend from transversely opposite side edges of the rear section 7, respectively. A pair of cuffs 10 longitudinally extend on the inner surface of the diaper 1 along transversely opposite sides of the diaper 1 across the front and rear sections 6, 7 as well as the crotch section 8 so that these cuffs 10 may bear against the wearer's crotch as the diaper 1 is worn. Each leg surrounding flap 11A is cut away to form a circular-arc-shaped notch outside the associated cuff 10 and an elastic member (second elastic member) 16 is bonded in its stretched state to the inner surface of the backsheet 3 in parallel to and inside the circular arc. Reference numeral 10A in Fig. 1 designates each cuff 10 shown in a plan view as before it is bonded to the inner surface of the diaper 1. The cuff 10A is made of a crescent-shaped strip of elastic sheet and preferably has its upper and lower ends 23 as viewed in Fig. l (i.e., longitudinally opposite ends with respect to the diaper 1) cut away and is bonded to the inner surface of the diaper 1 along a bonding margin 17 as indicated by oblique lines so as to obtain the cuff 10 adapted to be risen on its new ends 18 as well as an outer circular arc 19 defined between these new ends 18. It should be understood here that a linear distance between the ends 18 of the cuff 10A is dimensioned to be shorter than a linear distance between longitudinally opposite ends of the diaper 1 and the cuff 10A is bonded to the inner surface of the diaper so that the topsheet 2 may be curved in accordance with the outer circular arc 19 or the cuff 10A is bonded in its appropriately stretched state to the inner surface of the diaper 1 at the desired region. With the diaper 1 having such cuff 10, the cuff 10 is normally biased under the contraction of itself to be risen so that the diaper 1 is curved with its inner surface being concaved and with an inner circular arc 15 of the cuff 10 serving as a free edge bearing against the wearer's crotch. The cuff 10 configured substantially in crescent-shape allows the height of the risen cuff 10 to be maximized in the crotch section 8 and progressively reduced toward the front and rear sections 6, 7, leaving the negligibly small bonding margins at the longitudinally opposite ends 11B of the diaper 1. Such cuff 10 assures comfort to the wearer, since it does not make the diaper 1 bulky in the proximity of the longitudinally opposite ends 11B of the diaper 1. Referring to Fig. 3, while the cuff 10 is configured substantially in a crescent-shape, the bonding margin 17 along which the cuff 10 is bonded to the inner surface of the diaper 1 is dimensioned to be sufficiently large to cover the leg surrounding flap 11A as well as wings 22 of the front and rear sections 6, 7 and to define a substantially same outline as that of the diaper 1. Such a configuration of the cuff 10 is preferable when there is an apprehension that the bonding margin 17 of the cuff 10 bonded to the topsheet 2, in the embodiment of Fig. 1 might make a difference in thickness undesirable for comfort to the wearer or that body fluids diffused in the plane of the topsheet 2 might ooze out on the surfaces of the leg surrounding flap 11A and the wings 22. For the invention, the cuff 10 may be made of an elastic sheet material such as an elastic nonwoven fabric of composite fibers or melt blown fibers or an elastic plastic film, for example, an elastomeric film. Such sheet material is preferably water-repellent, liquid-impermeable or air-permeable but liquid-impermeable. The top- and backsheets 2, 3 and the other members may be made of materials usually employed in this technical field and, for bonding of these members, adhesive such as hot melt adhesive, gluing agent and welding technique may be employed. With the disposable diaper of the invention, the configuration of the cuff substantially in crescent-shape allows the height of the risen cuff to be relatively high without the apprehension that the longitudinally opposite ends of the diaper might be made bulky due to such dimensioning and thus significantly improve the comfort to the wearer compared to the prior art.

Claims: A disposable diaper (1) comprising a liquid-permeable topsheet (2), a liquid-impermeable backsheet (3) and a liquid-absorbent core (4) sandwiched between these two sheets (2,3) so as to form a front section (6), a rear section (7) and a crotch section (8) longitudinally interposed between these two sections (6,7), a pair of elasticized side flaps (11A) formed by portions of the topsheet (2) and the backsheet (3) extending outwardly of transversely opposite sides of said core (4), each of said side flaps (11A) having an outer side edge, and a pair of elasticized cuffs (10) longitudinally extending on an inner surface of said diaper (1) along transversely opposite sides thereof across the crotch section (8) and normally tending to rise above said inner surface in a crescent shape; characterised in that each cuff (10) is made of an elastic sheet configured substantially in said crescent shape, each cuff (10) extends across the front and rear sections (6,7) of said diaper (1) as well as across said crotch section (8), and each cuff (10) has a bonding zone (17) extending outwardly along an arc-shaped outer edge (19) of said cuff (10), is bonded in a longitudinally stretched state to a portion of said side flap (11A) between the side edge of said core (4) and the outer side edge of said side flap (11A) at longitudinally opposite ends (18) thereof and along said bonding zone (17), and covers at least a portion of the area of said side flap (11A) extending outwardly from said arc-shaped outer edge (19). A disposable diaper (1) according to Claim 1, wherein each side flap (11A) is elasticized with an elastic member (16) disposed longitudinally adjacent an outer side edge of said side flap (11A), and said cuffs (10) are disposed inwardly from said elastic members (16). A disposable diaper according to claim 1 or 2, wherein the bonding zone (17) substantially covers the area of each side flap (11A) extending outwardly from said arc-shaped outer edge (19) of each cuff (10).

Inventors: HIROTOMO MUKAI, MASAMITSU YAMAMOTO, TAKAMITSU IGAUE, YOSHIHISA FUJIOKA, HIROTOMO, MUKAI, MASAMITSU, YAMAMOTO, TAKAMITSU, IGAUE, YOSHIHISA, FUJIOKA
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 1995
Main classification: A61F13
IPC codes: A61F13, A61F5