Disposable absorbent garments

Abstract: Here is disclosed an arrangement of elastic means (4A-4D) surrounding respective leg-openings (14) of garments (L) such as disposable diaper, wherein the elastic means surrounding each of the leg-openings comprises a plurality of first elastic members and a plurality of second elastic members; the first elastic members (4A) are positioned substantially along a front half of the leg-opening while the second elastic members (4B) are positioned substantially along a rear half of the leg-opening; the first and second elastic members have their tensile stress gradually decreasing from their longitudinally inner ends (4A2,4B2) toward their longitudinally outer ends (4A1,4B1); and the first and second elastic members have their inter-member spacings gradually enlarged from their longitudinally inner ends toward their longitudinally outer ends.

Description: BACKGROUND OF THE INVENTION The present invention relates to disposable garments and more particularly to such garments such as diaper, incontinence pants and baby training pants. A garment as defined in the preamble of claim 1 is disclosed in EP-A-0048011. The garments of such type are usually provided around the respective leg-openings with the elastic means. In general, the elastic means are bonded, under stretching, to at least one of the topsheet and the backsheet with adhesive. With the particular garments, for example, a disposable diaper, undesirable leakage of excretions often occurs, regardless of the user's gender, at the opposite side of the crotch area defined between the opposite leg-openings due to location and orientation of the urinary organs. In view of a fact that, after put on the user, the diaper can move relative to the wearer's skin at the upper middle area of each leg-opening more easily than at said lower middle area, it is preferred also to decentralize the tensile stress of the elastic means at said upper middle area, allowing the diaper to contact with the wearer's skin over a relatively large area with a moderate fitness. In the EP 81 19861, publ. no. 0048011 there is disclosed a disposable garment where the elastic means are made of a single ribon, so that no decentralization can be achieved. In the WO 86/02530 the diaper comprises elastic means extending essentially perpendicularly to the waistband and being attached in the diaper material with a continuously varying tension. It is an object of the invention to provide the disposable garments including the elastic means surrounding each leg-opening which has a tensile stress gradually decentralized from adjacent the lower middle area toward adjacent the upper middle area of the leg-opening, and to provide a method for manufacturing such a garment. SUMMARY OF THE INVENTION The object set forth above is achieved, according to the invention, by disposable garments as has been described above, wherein the elastic means surrounding each of the leg-openings comprises a plurality of first elastic members and a plurality of second elastic members and the first and second elastic members have their inter-member spacings gradually enlarged from their longitudinally inner ends toward their longitudinally outer ends. In a preferred embodiment, the first and second elastic members surrounding each of the leg-openings are continuous to those surrounding the opposite leg-opening, respectively, and intermediate lengths of the respective continuous elastic members connecting the opposite leg-openings extend across the crotch area transversely thereof. In this manner the tensile stress of the first and second elastic members is transversely decentralized in the proximity of the upper middle area of each leg-opening, since the first and second elastic members comprise a plurality of members, respectively, and their inter-member spacings are gradually enlargend from their longitudinally inner ends toward their longitudinally outer ends. Furthermore, the invention allows the garments to contact with the wearer's skin at adjacent the lower middle area of each leg-opening under a higher fitness than at the upper middle area thereof, since the first and second elastic members have the tensile stress gradually decreasing from their longitudinally inner ends toward their longitudinally outer ends, i.e., gradually increasing from their longitudinally outer ends toward their longitudinally inner ends. By using such garments of the invention, leakage of excretions readily occuring through the lower middle area of each leg-opening which has conventionally been remarkable and almost inevitable can be now effectively alleviated, since the invention allows the elastic members to contact with the wearer's skin in the proximity of the lower middle area of each leg-opening under a relatively firm fitness. In addition, the upper area of each leg-opening most readily movable relative to the wearer's skin can be maintained in contact with the wearer's skin under a relatively weak tensile stress but over a large area, since the tensile stress of the elastic members is decentralized in the vicinity of the upper area of each leg-opening. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing an embodiment of the garments constructed in accordance with the teaching of the invention; Fig. 2 is an exploded perspective view of the garments; and Fig. 3 is a plan view showing by way of example a manner in which elastic means is arranged. PREFERRED EMBODIMENT OF THE INVENTION The other features and advantages of the invention will be readily understood from the following description made in reference with the accompanying drawings. Referring first to Fig. 1, a diaper of pants type 1 is shown in a perspective view. As shown, the diaper 1 has leg-openings 2 and a waist-opening 3, both being provided with elastic means 4, 5, respectively. Referring to Fig. 2, the same diaper 1 is shown in an exploded perspective view. As illustrated, the diaper 1 comprises a water-permeable topsheet 6 being stretchable both in length and width, a water-permeable backsheet 7 being also stretchable both in length and width, a mat- or sheet-like water-absorbent core 8, and the elastic means 4, 5 surrounding the leg-openings 2 and the waist-opening 3, respectively. Front and rear sections 10, 11 of the top-and backsheets 6, 7 define between the front and rear sections 10, 11 a crotch area 12 having opposite side edges formed with identical notched edges 13, 14, respectively, so as to define the respective leg-openings 2. The backsheet 7 may include water-impermeable plastic film (not shown) being stretchable both in length and width and bonded to the inner side of the backsheet 7 with adhesive intermittently applied thereto. Such arrangement will perfectly prevent excretions from passing through the backsheet 7. Where the film is bonded at least along its outer peripheral area to the topsheet 6 with intermittently placed spots of adhesive, the top- and backsheets 6, 7 as components of the diaper 1 will be improved not only in elasticity but also in tensile stress and thereby a fitness characteristic of the diaper 1 on the wearer's body will be further improved. The elastic means 4 associated with the leg-openings comprises a plurality of first elastic members 4A and a plurality of second elastic members 4B. The first and second elastic members 4A, 4B extend in parallel to each other along their intermediate lengths 4A2, 4B2 and intersect each other substantially at middle points along the respective notched edges 13, 14, then extensions 4A1, 4B, diverge from the respective intersections 4C so as to extend along the respective notched edges 13, 14. The divergent extensions 4A1, 4B1 are bonded to the inner surface(s) of the back- and/or topsheet(s) with adhesive 17 but the intermediate parallel lengths 4A2, 4B2 are positioned in substantially in a central area of the core across the crotch area 12 without being bonded to any of the back- and topsheets. A plurality of the first elastic members 4A and a plurality of the second elastic members 4B are so arranged to have their inter-member spacings along the respective divergent extensions 4A1, 4B1 gradually enlarged from their longitudinally inner ends 4C (said respective intersections) toward their longitudinally outer ends 4D, i.e., gradually reduced from their longitudinally outer ends 4D toward their longitudinally inner ends 4C (said respective intersections). The first and second elastic members 4A, 4B are so arranged that the respective divergent extensions 4A1, 4B1, have the tensile stress gradually decreasing from their longitudinally inner ends (said respective intersections) 4C corresponding to bottoms of the respective leg-openings toward their longitudinally outer ends 4D corresponding to tops of the respective legopenings, i.e., gradually increasing from their longitudinally outer ends 4D toward their longitudinally inner ends 4C. Fig. 3 is a plan view illustrating by way of example the manner in which the first and second elastic members 4A,4B are arranged as has been described above. Adhesive is applied onto the backsheet 7 at given intervals longitudinally thereof so as to surround successive ellipses and thereby to define adhesive areas 17' while the backsheet 7 is moved longitudinally thereof at a given velocity. Simultaneously, a plurality of the first continuous elastic members 4A and a plurality of the second continuous elastic members 4B, both being stretched at a given elongation percentage, are inserted into the corresponding number of first and second traverses (not shown) which are, in turn, activated so that the first and second elastic members 4A, 4B are bonded to the backsheet 7 along the adhesive areas 17', describing curves substantially corresponding to sine curves. These curves are symmetric with respect to a longitudinally centre line of the backsheet 7. The first and second elastic members 4A, 4B travel from a starting point Pl to a turning point P2, then from the turning point P2 to the new starting point Pl, respectively, by a width W for each cycle. Their elongation percentage increases during travel from the starting point P₁ to the turning point P₂ and consequently their tensile stress also increases, since the first and second elastic members 4A, 4B under stretching with a given elongation percentage having been linearly traveling longitudinally of the backsheet 7 are forcibly deflected by said traverses transversely of the backsheet 7, resisting against such deflection, and, in consequence, the first and second elastic members 4A, 4B are stretched in the course of traveling from the starting point P₁ to the turning point P₂, respectively. It will be understood that said elongation percentage depends upon the velocity at which the first and second elastic members 4A, 4B are fed longitudinally of the backsheet 7 as well as the velocity at which said traverses move transversely of the backsheet 7. Meanwhile, spacings of component elastic members in each plurality of elastic members 4A, 4B are reduced as each plurality of elastic members 4A, 4B having been linearly traveling longitudinally of the backsheet 7 is forcibly deflected by the associated traverse transversely of the backsheet 7 from the starting point P₁ to the turning point P₂. It will be understood here again that a degree of such inter-member spacing reduction depends upon the velocity at which the first and second elastic members 4A, 4B as well as the backsheet 7 travel. The lengths (the intermediate parallel length 4A₂, 4B₂ in Fig. 2) of the first and second elastic members 4A, 4B extending between each pair of intersections 4C and being closely adjacent to each other are loosened to be brought further close together since the area of the backsheet 7 corresponding to these intermediate parallel lengths 4A₂, 4B₂ carries no adhesive. However, these intermediate parallel lengths also may be bonded to the backsheet 7 with adhesive, if desired, by applying adhesive onto said area of the backsheet 7 or the first and second elastic members 4A, 4B may be entirely coated with adhesive. In the latter case, obviously no adhesive will be applied onto the backsheet 7 at all. The elastic means 5 surrounding the waist-opening is bonded to inner surface(s) of the top- and/or backsheet(s) with adhesive along a waist line 16. Though not shown, the core 8 is bonded, on its top side and/or bottom side, to the topsheet 6 and/or the backsheet 7 with spots of adhesive intermittently placed thereon. A laminar structure formed in this manner may be folded in two along its longitudinally centre line and then opposite free edges thereof may be joined together by means of heat seal to provide the individual diaper 1 as shown by Fig. 1. Such diaper 1 may be obtained by employing the method for making disposable briefs as disclosed in Japanese Patent Application No. 1989-167224 (EP-A-0405575) filed in the name of the same applicant as of the present application. However, it should be understood that the present invention is not limited to the form of pants or briefs. Specifically, it is possible within the scope of the invention that, instead of folding said laminar structure along its longitudinally centre line in two followed by joining the opposite free edges together by means of heat seal, the rear section 11 of said laminar structure is provided at opposite sides with suitable fastener means such as strips of pressure tape by which the waist line 16 of the laminar structure (garments) is fixedly completed as in the case of so-called open type diaper. It is also possible even to omit the core 8, depending upon the type of garments. The topsheet 6 and the backsheet 7 may be of water-permeable nonwoven fabric being stretchable both in length and width, the core 8 may be of fluffy pulp mixed with hightly water-absorbent polymer particles, and the elastic members may be of natural or synthetic rubber or the like.

Claims: Disposable garment (1) having a topsheet (6), a backsheet (7) and elastic means (4) provided along leg-openings (2) defined at opposite sides of a crotch area (12) connecting front and rear sections (10, 11) of the top- and backsheets, characterized in that the elastic means (4) surrounding each of the leg-openings (2) comprises a plurality of first elastic members (4A) and a plurality of second elastic members (4B): the first elastic members (4A) are positioned substantially along a front half of said leg-opening while the second elastic members are positioned substantially along a rear half of the leg-opening so that the first and second elastic members intersect (4C) each other at their longitudinally inner regions located adjacent a lower middle area of the leg-opening; and the first and second elastic members (4A, 4B) have their inter-member spacings gradually enlarged from the longitudinally inner regions (4C) toward their longitudinally outer ends (4D). Disposable garment as claimed in Claim (1), wherein the first and second elastic members (4A, 4B) have their tensile stress gradually decreasing from their longitudinally inner regions (4C) toward their longitudinally outer ends (4D). Disposable garment as claimed in Claim 1 or 2, wherein the first and second elastic members (4A, 4B) surrounding each of the leg-openings (2) are continuous to those surrounding the opposite leg-opening, respectively, and intermediate lengths of the respective continuous elastic members connecting the opposite leg-openings extend across said crotch area (12). Method for manufacturing a disposable garment (1) as recited in Claim 1, characterized by the steps: applying adhesive onto the backsheet at given intervalls longitudinally thereof so as to surround successive ellipses, while the backsheet (7) is moved longitudinally at a given velocity, simultaneously, a plurality of the first continous elastic members (4A) and a plurality of the second continuous elastic members (4B), both being stretched at a given elongation percentage, being inserted into the corresponding number of first and second traverses which are, in turn, activated so that the first and second elastic members (4A, 4B) are bonded to the backsheet (7) along the adhesive areas (17'), describing curves substantially corresponding to sine curves, so that the first and second elastic members travel from a starting point (P₁) to a turning point (P₂), then from the turning point (P₂) to the new starting point (P₁), respectively, by a width (W) for each cycle, whereas their elongation, percentage being increased during traveling from point (P₁) to turning point (P₂) and wherein spacings of component elastic members in each plurality of elastic members (4A, 4B) being reduced as each plurality of elastic members (4A, 4B) having been linearly traveling longitudinally of the backsheet (7) being forcibly deflected by the associated traverse transversely of the backsheet (7) from the starting point (P₁) to the turning point (P₂). Method as recited in claim 4 wherein the first and second elastic members (4A, 4B) under stretching with a given elongation percentage having been linearly traveling longitudinally of the backsheet (7) are forcibly deflected by said traverses transversely of the backsheet (7), resisting against such deflection, and, in consequence, stretched in the course of traveling from the starting point (P₁) to the turning point (P₂), respectively. Method as recited in claim 4 and 5 wherein the elongation percentage depends upon the velocity at which the first and second elastic members (4A, 4B) are fed longitudinally of the backsheet (7) as well as the velocity at which said traverses move transversely of the backsheet. Method as recited in the aforegoing method claims, wherein the degree of such inter-member spacing reduction depends upon the velocity at which the first and second elastic members as well as the backsheet (7) travel. Method as recited in the aforegoing method claims, wherein the intermediate lengths (4A₂, 4B₂) of the first and second elastic members (4A, 4B) extending between each pair of intersections (4C) and being closely adjacent to each other are loosened to be brought further close together since the area of the backsheet (7) corresponding to these intermediate parallel lengths (4A₂, 4B₂) carries no adhesive. Method as recited in the aforegoing method claims, wherein the intermediate parallel lengths (4A₂, 4B₂) are bonded to the backsheet (7) with adhesive, by applying adhesive onto said area of the backsheet (7) or the first and second elastic members (4A, 4B) may be entirely coated with adhesive.

Inventors: MATSURA YOSHINORI, NOMURA HIRONORI, OHNISHI HIROFUMI, SASAKI TOHRU, MATSURA, YOSHINORI, NOMURA, HIRONORI, OHNISHI, HIROFUMI, SASAKI, TOHRU
Applicants: UNI CHARM CORP, UNI-CHARM CORPORATION
Application year: 1990
Main classification: A61F13
IPC codes: A61F5, A61F13, A41B9