Disposable absorbent article

Abstract: A disposable absorbent article (1) comprises a strip (10) of soft, stretchable and liquid-resistant sheet material bonded to a topsheet (2) of said article (1) on its upper surface along one (11) of transversely opposite sides of said strip (10). Then a portion of said strip (10) extending outward from said article (1) is folded along its transversely intermediate line (13) back onto a backsheet (3), and the other side (14) of said strip (10) opposed to said one side (11) bonded to said topsheet (2) is bonded to said backsheet (3).

Description: The present invention relates to disposable absorbent articles such as menstruation pads, diapers, training pants, incontinent pants and pads. There are well known disposable absorbent articles comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, a liquid-absorbent core disposed between these two sheets and a pair of side flaps extending outward beyond transversely opposite side edges of the absorbent core, respectively. The top-and backsheets are made of sheet materials, for example, a nonwoven fabric and/or a plastic film. These top-and backsheets are bonded to each other in their areas extending outward beyond the transversely opposite side edges of the absorbent core to form the side flaps. The side flaps not only provide a zone over which the top- and backsheets are bonded to each other but also fit around the wearer's legs to prevent body fluids from sideways leaking. In the case of a menstruation pad, they cover the shorts (pants) worn by the wearer of the pad along transversely opposite side edges of its crotch zone and thereby protect the side edges of the shorts against being smeared with menstrual discharge. However, the side flaps and the outer edges thereof formed in the manner as described above are nothing but the portions of the top- and backsheets bonded together and their cut ends, respectively. Accordingly, even if both the top- and backsheets themselves are of soft materials, once they have been bonded together, the side flaps formed by these soft sheets may have a relatively high rigidity and give the wearer's soft skin particularly over the crotch zone and therearound an uncomfortable feeling. Specifically, the outer edges of the respective side flaps defined by the cut ends of the top- and backsheets bonded together may unbearably irritate the wearer's skin like sharp edges. In EP-A-0534488, an absorbent article, such as a sanitary napkin, comprises a liquid-permeable topsheet, a liquid-impermeable backsheet and an absorbent core disposed therebetween. The top- and backsheets are attached to each other along the longitudinal sides of the core to form side flaps, and a strip of soft material, which may be elastic and liquid-resistant, is looped over the outer edges of the top- and backsheets so as to form a compliant cuff which bears against the wearer's body in a comfortable manner. An elastic member placed in tension so as to impart an arcuate shape to the article may be placed inside a cavity formed by the cuff. It is a principal object of the invention to provide a disposable absorbent article having improved side flaps with respect to the side flaps of the afore-mentioned known disposable articles. Accordingly, the present invention consists in a disposable article as defined in claim 1. With the absorbent article as described above, each side flap comprises the soft, stretchable and liquid-resistant strip folded back along the transversely intermediate line of the strip's portion outwardly extending beyond the topsheet with the fold defining the outer side edge of the side flap, so there is no apprehension that the outer side edge might irritate the wearer's skin. The side flaps are bonded with a longitudinal tension to the article in order to assure that the article may be appropriately curved and put closely against the wearer's skin over the crotch as well as therearound under the effect of the side flaps' contraction occurring as the article is worn. The invention will now be described by way of example with reference to the accompanying drawings, in which:- Fig. 1 is a plan view showing a menstruation pad as a disposable absorbent article in accordance with one embodiment of the invention; and Fig. 2 is a sectional view taken along a line Y - Y in Fig.1. Referring to the Figs., a menstruation pad 1 comprises a longitudinally long basic body 5 including a liquid-permeable topsheet 2, a liquid-impermeable backsheet 3 and a liquid-absorbent core 4 disposed between these two sheets 2, 3, and a pair of side flaps 6 on both sides of the basic body 5. The top- and backsheets 2, 3 are water-tightly bonded to each other in their end portions extending outward beyond longitudinally opposite ends 4A of the core 4, on one hand, and bonded, in the proximity of transversely opposite side edges 4B of the core 4, to longitudinal long strips 10 of a soft, stretchable and liquid-resistant sheet material, respectively which are destined to form the side flaps 6, on the other hand. The top- and backsheets 2, 3 extend outward slightly beyond the transversely opposite side edges of the liquid-absorbent core 4 to form relatively narrow side flaps 20 and thereon the strips 10 are bonded to the top- and backsheets 2, 3 along longitudinal welding lines 21, respectively, to form the side flaps 6 extending outward from the respective welding lines 21 as well as side flaps 22 extending inward from the respective welding lines 21 to above the core 4 so that the respective side flaps 22 may cooperate with the topsheet 2 to form pockets 26 which are openable inwardly of the pad 1. Referring to Fig. 1, in areas of each strip 10 shaded by oblique lines 25, each strip 10 has its mutually opposed inner surfaces bonded to each other and to the upper surface of the topsheet 2 or to the lower surface of the backsheet 3. So far as the first side flaps 6 are concerned, the mutually opposed inner surfaces of each strip 10 may be bonded to each other or left in freely overlying relationship. They may be bonded to each other along a line 21 parallel to the core side edge 4B spaced inward from an outer side edge 13 of each side flap 6 so that they may define a tunnel 24 having a pump action to flow air therethrough when the tunnel is pushed against the wearer's skin. The strips 10 are bonded with a longitudinal tension to the basic body 5 in order to assure that the side flaps 22 tend to rise on the topsheet 2 under the effect of their elastic contraction as the pad 1 is worn. As a result, the pockets 26 are opened as shown by Fig.2. The strip 10 are of stretchable material such as a stretchable nonwoven fabric obtained by crimping composite fibers, a melt-blown nonwoven fabric made from stretchable fibers, or a stretchable sheet of elastomer or rubber. When fibrous materials are employed, their fineness are preferably less than 5 deniers and more preferably less than 2 deniers. The strip 10 preferably has a weight per unit area less than 100 g/m 2 and more preferably less than 50 g/m 2 to obtain desired softness as well as stretchability. It is required for such strip 10 to have an ability of limiting or preventing the body fluids from soaking in the direction of its thickness or spreading therethrough in its planar direction, i.e., a water-proofness. The strip 10 may be subjected to a water repellent finish or the like, if desired. Bonding between the mutually opposed inner surfaces of the strip 10 as well as between the strip 10 and the top- and backsheets 2, 3 should be of water-impervious nature and, to achieve this, it is preferable to provide at least the welding lines in the form of longitudinally continuous lines. It should be understood that the welding lines can be effectively employed only when the top- and backsheets 2, 3 as well as the strip 10 are of fusible nature, so these welding lines may be replaced by corresponding lines of hot melt adhesive or the like, if necessary. To avoid leakage of the body fluids possibly occurring along the longitudinally opposite ends of each side flap 6, the strips 10 should be bonded to the backsheet 3. In this manner, the body fluids may spread through the topsheet 2 in its planar direction but never spread over the upper surfaces of the respective strips 10. As will be apparent from the foregoing description, each side flap (more strictly, each first side flap) comprises the soft, stretchable and liquid-resistant strip folded back along its transversely intermediate line with the fold defining the outer edge of this side flap, so there is no apprehension that the outer edge might irritate the wearer's skin. Such side flap can be effectively employed also for the other various wearing articles or garments including disposable diapers, training pants, incontinent pants and absorbent pads. The other important feature of the invention is that the side flaps are formed by bonding said strips with a longitudinal tension to the basic body which facilitates the pad as well as the garment to be maintained in close contact with the wearer's crotch, since they are appropriately curved under the effect of the side flaps' contraction occurring as the pad or other garment is worn.

Claims: A disposable absorbent article comprising a liquid-permeable topsheet (2), a liquid-impermeable backsheet (3), a liquid-absorbent core (4) disposed between these two sheets (2,3), and a pair of first side flaps (6) extending along transversely opposite side edges (4B) of said core (4), wherein said top- and backsheets (2,3) extend outward beyond said transversely opposite side edges (4B) of said core (4) to form side flaps (20), and each of said first side flaps (6) is formed by bonding a strip (10) of soft, stretchable and liquid-resistant sheet material to said topsheet (2) of said side flap (20) on its upper surface along one of transversely opposite sides of said strip (10), folding a portion of said strip (10) extending outward from the associated side edge (4B) of said core (4) along a transversely intermediate line of said portion back onto said backsheet (3), and bonding the other side of said strip (10) to said backsheet (3) of the side flap (20), and a second side flap (22) extends inward from an inner side edge of each of said first side flaps (6), which are bonded to said topsheet (2), to above said core (4) and thereby defines a pocket (26) in cooperation with said topsheet (2) wherein said bonding of said strips (10) to the article is performed with a tension along the transversely opposite side edges (4B) of said core (4); characterized in that : - (a) said side flaps (20) are narrow; (b) the one side of each said strip (10) is bonded to the upper surface of said topsheet (2) of the narrow side flap (20) at a position in the proximity of the associated side edge (4B) of said core (4) and the other side of each said strip (10) is bonded to the lower surface of said backsheet (3) of the narrow side flap (20) at a position in the proximity of the associated side edge (4B) of said core (4); and (c) the inner surface of each second side flap (22) contacts the associated side edge (4B) of said core (4) with said topsheet (2) disposed therebetween. A disposable absorbent article according to Claim 1, wherein mutually opposed inner surfaces of each said side flap (6) extending outward from said core (4) are bonded to each other along a longitudinal welding line (21), apart inward from an outer side edge (13) of said side flap (6) and thereby define a tunnel (24) having a pump function to communicate air therethrough between said welding line (21) and said outer side edge (13).

Inventors: MIZUTANI SATOSHI, MIZUTANI, SATOSHI
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 1995
Main classification: A61F13
IPC codes: A61F13, A61F5