Disposable diaper

Abstract: A disposable diaper (1) has a pair of hooked fastener components (15) serving to connect front and rear waist regions (6,7) of the diaper in a separable manner. The hooked fastener components (6,7) are bonded to transversely opposite sides, respectively, of the front or rear waist regions (6,7) and are covered with soft sheets (18), respectively, except in a middle zone thereof and an inner zone of the hooked fastener components (15) extending laterally towards a middle line of the diaper, such that the wearer's skin is prevented from being irritated by the hooked fastener.

Description: The present invention relates to a disposable diaper having front and rear waist regions adapted to be separably connected to each other in its actual use. In disposable diapers, it is known to provide a pair of fastening zones on transversely opposite side edges of front or rear waist regions of the diaper so that these fastening zones may be peelably fastened to the other waist region in actual use of the diaper. It is also a commonly used technique to form such fastening zones by using a hooked fastener component or a looped fastener component constituting together a. surface fastener which is known under the trademark of Velcro. In such a diaper, the components of the surface fastener generally present a rigidity higher than the other parts of the diaper such as the topsheet and backsheet and this high rigidity sometimes irritates the baby's skin. In addition, the surface fastener component must be firmly bonded to the topsheet or backsheet in consideration of the fact that the surface fastener component of high rigidity bonded to the relatively soft topsheet or backsheet is repeatedly fastened to and peeled off from the outer surface of the diaper and a peeling force is generated on the interface between the soft sheet and the surface fastener component as the latter is peeled off from the outer surface of the diaper. However, such firm bonding increases the rigidity of the surface fastener component, and irritation of the baby's skin due to the relatively sharp peripheral edge of the fastener component can become serious. GB-A-2284742 discloses, in one embodiment shown in Figure 7, a disposable diaper having a tape fastening tab comprising a substrate member with a hooked fastener component on the attaching surface thereof. The outer end of the substrate member is folded inwardly to cover an outer region of the hooked fastener component and thereby form a finger tab 70. EP-A-0563457 discloses an adhesive/mechanical fastener system for a disposable diaper, in which a mechanical fastening member is attached to a tape tab fastener and an additional piece of material extends over part of the mechanical fastening member so as to provide additional attachment of the mechanical fastening member to the tape tab fastener. It is therefore a principal object of the invention to provide an improved disposable diaper which allows both the peeling force acting on the peripheral edge of the surface fastener component and the skin irritation due to the peripheral edge to be alleviated. Accordingly, the present invention consists in a disposable diaper comprising a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core diposed between the two sheets, wherein said diaper has a front waist region, a rear waist region and a crotch region extending between the front and rear waist regions, a pair of extensions each having an outer side edge and an inner side edge and extending outward from transversely opposite sides of said rear waist region, a pair of hooked fastener components attached to an inner surface of said pair of extensions and having a plurality of hook elements, a pair of looped fastener components attached to an outer surface of said front waist region and having a plurality of loop elements adapted to be separably interlocked with said hook elements of said hooked fastener components, and said hook elements positioned along at least a laterally outer edge of the peripheral edges of each of said hooked fastener components being covered; characterised in that:- (a) said covered hook elements are covered by a protective sheet which is softer than said hooked fastener components; (b) the outer side edge of each extension extends outwardly beyond said laterally outer edge of said hooked fastener component attached thereto; and (c) said outer side edge is also covered by said protective sheet to define a tab to be held by the user's fingers. The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which:- Fig.1 is a plan view, partially broken away, showing an embodiment of the inventive diaper; Fig.2 is a sectional view taken along a line II-II in Fig. 1; Fig 3. is a fragmentary plan view showing an alternative embodiment of the inventive diaper; and Fig. 4 is a sectional view taken along a line IV-IV in Fig. 3. A diaper 1 shown by Fig. 1 in a plan view as partially broken away comprises a liquid-permeable topsheet 2, a liquid-impermeable backsheet 3 and a liquid-absorbent core 4 disposed between these two sheets 2, 3. The diaper has a front waist region 6, a rear waist region 7 and a crotch region 8 extending between these two waist regions 6, 7. The front and rear waist regions 6, 7 are provided along their transversely opposite sides with front wings 11 and rear wings 12, respectively. The topsheet 2 and backsheet 3 are put one upon another over their portions extending outward beyond a peripheral edge of the core 4 and inner surfaces of these portions are water-tightly bonded together. The crotch region 8 is provided adjacent its transversely opposite side edges with elastic members 13 adapted to surround the baby's legs and the rear waist region 7 is provided adjacent its longitudinal end with an elastic member 14 extending along the waist line. These members 13, 14 are disposed between the topsheet 2 and backsheet 3 and secured in an elastically contractible condition to the inner surface of at least one of these two sheets 2, 3. A hooked fastener component 15 having a plurality of hook elements, one component of the surface fastener commonly known under the trademark of Velcro, is integrally bonded to the inner surface of each rear wing 12 and a part of this hooked fastener component 15 extending laterally to an outer side edge 12A of the wing 12 has its inner surface covered with a protective sheet 18. A looped fastener component 16 having a plurality of loop elements, the other component of the surface fastener, is integrally bonded on its lower side to the outer surface of the front waist region and wing 6, 11. Fig. 2 is a sectional view taken along a line II-II in Fig. 1. As shown, an inner side edge 12B of each rear wing 12 is bonded to a side edge of the outer surface of the backsheet 3 and only a portion of the hooked fastener component 15 defined by a width A is exposed. The component 15 can be interlocked with the associated looped fastener component 16 on the front waist region 6 over a portion defined by the width A, but can not be interlocked with the component 16 over its outer portion defined by a width B and covered with the protective sheet 18. The hooked fastener component 15 once interlocked with the associated looped fastener component 16 may be pulled in the direction as indicated by an arrow P with the outer side edge 12A of the rear wing 12 being held by the user's fingers to peel off the portion defined by the width A starting from its right side, as indicated by the imaginary lines. In this state, the so-called peeling force is practically ineffective between the rear wing 12 and an outer edge 20 of the hooked fastener component 15, so the outer edge 20 is not easily peeled off from the rear wing 12. The outer edge 20 is covered with the protective sheet 18 and therefore does not irritate the wearer's skin. Figs. 3 and 4 are respectively a fragmentary plan view showing an alternative embodiment of the inventive diaper and a sectional view taken along a line IV-IV in Fig. 3. According to this embodiment of diaper 1, the hooked fastener component 15 of square shape has its peripheral edge entirely covered with the sheet 18 and is thus even less likely to irritate the wearer's skin than in the previously described embodiment with reference to Figs. 1 and 2. As the protective sheet 18 is used to alleviate skin irritation due to the hooked fastener component 15, it is preferred to employ, as this protective sheet 18, nonwoven fabric or plastic film which is less rigid than the component 15 and agreeable to the touch. The sheet 18 is bonded to the inner surface of the rear wing 12 adjacent the peripheral edge of the component 15 and, if desired, the sheet 18 may be also bonded to the upper surface of the component 15. To implement the inventive diaper 1, the front and rear wings 11, 12 may be formed by liquid-permeable or liquid impermeable nonwoven fabric or plastic film. Alternatively, the topsheet 2 and/or the backsheet 3 may be laterally further extended to form the front and rear wings 11, 12. Bonding of the respective components or members may be achieved by use of adhesive, e.g. , of hot melt type or by utilizing a heat-seal technique so far as the components or members to be bonded are of a heat-sealable nature. It should be understood that no specific manner of such bonding is illustrated. While the looped fastener component 16 on the front waist region 6 is relatively soft and therefore not covered with the protective sheet 18 in the illustrated embodiment, the component 16 also may be covered with the protective sheet 18 similarly to the component 15, if it is desired. The inventive disposable diaper effectively avoids an apprehension that the relatively sharp peripheral edge of the surface fastener components connecting the front and rear waist regions of the diaper in actual use might irritate the wearer's skin by covering the peripheral edge of the surface fastener components with the soft protective sheet. Such covering with the protective sheet is effective also to prevent the surface fastener components from being unintentionally peeled off from the diaper.

Claims: A disposable diaper comprising a liquid-permeable topsheet (2), a liquid-impermeable backsheet (3) and a liquid-absorbent core (4) disposed between the two sheets (2,3), wherein said diaper has a front waist region (6), a rear waist region (7) and a crotch region (8) extending between the front and rear waist regions (6,7), a pair of extensions (12) each having an outer side edge (12A) and an inner side edge (12B) and extending outward from transversely opposite sides of said rear waist region (7), a pair of hooked fastener components (15) attached to an inner surface of said pair of extensions (12) and having a plurality of hook elements, a pair of looped fastener components (16) attached to an outer surface of said front waist region (6) and having a plurality of loop elements adapted to be separably interlocked with said hook elements of said hooked fastener components (15), and said hook elements positioned along at least a laterally outer edge of peripheral edges of each of said hooked fastener components (15) being covered; characterised in that :- (a) said covered hook elements are covered by a protective sheet (18) which is softer than said hooked fastener components (15); (b) the outer side edge (12A) of each extension (12) extends outwardly beyond said laterally outer edge of said hooked fastener component (15) attached thereto; and (c) said outer side edge (12A) is also covered by said protective sheet (18) to define a tab to be held by the user's fingers. A disposable diaper according to Claim 1, wherein said hook elements positioned along said peripheral edges of each of said hooked fastener components (15) are covered with said protective sheet (18).

Inventors: MISHINA YOSHITAKA, SAYAMA YASUSHI, MISHINA, YOSHITAKA, SAYAMA, YASUSHI
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 1996
Main classification: A61F13
IPC codes: A44B18, A61F13, A61F5