CA2107747C

CA2107747C - Disposable diapers

Info

Publication number: CA2107747C
Application number: CA002107747A
Authority: CA
Inventors: Tsutomu Kido
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 1992-10-15
Filing date: 1993-10-05
Publication date: 1998-07-21
Anticipated expiration: 2013-10-05
Also published as: JP2559053Y2; KR940009407U; TW418678U; KR200141299Y1; GB2271501A; JPH0634617U; ES2117082T3; CN2171340Y; AU672037B2; GB2271501B; EP0593082A1; AU4879493A; DE59308433D1; GB9321072D0; EP0593082B1; CA2107747A1

Abstract

A disposable diaper having a pair of projecting flaps inside longitudinally opposite ends of the diaper and projecting a certain distance in order to make a wearer feel comfortable. Elastic members are bonded, under tension in longitudinal direction of the diaper, to any one of portions of top- and backsheets extending beyond transversely opposite side edges of an absorbent core so that these elastic members lie within a necessary extent defined 30 mm or more inside the longitudinally opposite ends of the diaper with the intermediate section of these elastic members extending along a crotch zone.
The topsheet and/or the backsheet are folded along the respective elastic members toward the backside between longitudinally opposite ends, of the respective elastic members and the opposed inner sides of the folds are bonded together, respectively, to form the flaps adapted to rise on the topside of the diaper as it is put on a wearer.

Description

2 1 a 7 7 ~ rl DISPOSABLE DIAPERS

BACKGROUND OF THE INVENTION
This invention relates to disposable diapers.
It is well known to provide disposable diapers with side flaps extending between longitudinally opposite ends of such diapers and adapted to rise on the topside of such diapers as they are put on a wearer so that a quantity of body fluids may beeffectivelyprevented fromleaking throughlegopenings of such diapers. Such technique is disclosed, for example, by the specification of US Patent No. 4,704,116, according to which a liquid-permeable topsheet is partially folded so as to form sleeve-like flaps extending between the longitudinally opposite ends of a diaper and elastic members are bonded under tension longitudinally to these sleeve-like flaps so that these sleeve-like flaps may rise on the topside of the diaper as it is put on a wearer. Such a kind of techniqueiswell knownalso from JapanesePatent Application Disclosure Gazettes Nos. 1988-105102 and 1988-112703, in accordance with which there are separately prepared a pair of sleeve-likemembers eachhavinga lengthcorrespondingto the longitudinal dimension of a diaper and flaps are formed by bonding these sleeve-like members to the topsheet of the 2 i ~ 7 diaper. When the sleeve-like flaps or members are formed from a liquid-permeable sheet such as the topsheet, they are sometimes treated to obtain desired water-repellency to prevent body fluids from permeating therethrough.
Said flaps adapted to rise on the topside of the diaper as it is put on a wearer will be able to function in an expected manner so far as said flaps extend at least along the longitudinal dimension of a crotch zone. Nevertheless, the sleeve-likeflapsormembersaccordingtotheabove-mentioned prior arts fully extend between the longitudinally opposite ends, i.e., the opposite waist lines of the diaper and portionsof thesesleeve-like flapsormembers lying adjacent said opposite waist lines are collapsed and bonded to the topsheet. Such an arrangement is obviously disadvantageous in that the zones adjacent the front and rear waist lines become bulky and stiffy, causing the wearer to feel uncomfortable.
Accordingly, it is a principal object of the invention to solve the problem as has been mentioned above without a loss of a body fluid damming effect of flaps by folding portions oftop-and/orbacksheetsextendingoutwardfromtransversely opposite sides of an absorbent core of a diaper to form the flaps adapted to rise on the topside of the diaper as it is put on a wearer so that said flaps should not be beyond a necessary extent substantially corresponding to the longitudinal dimension of the crotch zone.

SUMMARY OF THE INVENTION
The object set forth above is achieved, according to a broad aspect of the present invention, by a disposable diaper which comprises a liquid-permeable topsheet having two spaced apart end portions and two spaced apart lateral sides. A liquid-impermeable backsheet is provided and has two spaced apart end portions and two spaced apart lateral sides. An absorbent core is sandwiched between the topsheet and the backsheet. The absorbent core has two spaced apart sides that are generally parallel the lateral sides of the topsheet and the lateral side of the backsheet, at a spaced distance inwardly from the lateral sides of the topsheet and the backsheet. A front body portion, a rear body portion, and a crotch zone intermediate the front body portion and the rear body portion is also provided. Two spaced apart laterally extending first flaps are formed from the topsheet and the backsheet. The first flaps extend along the crotch zone and are located laterally outwardly with respect to each the side of the absorbent core and located generally parallel to the sides of the absorbent core. Elastic members are mounted under tension in each of the first flaps between the topsheet and the backsheet. Two spaced apart second flaps are also provided. Each second flap is located intermediate one of the sides of the absorbent core and the adjacent first flap. The second flap also extends upwardly in a generally upstanding position which is generally at a right angle to a horizontal plane of said absorbent core.
The second flap also extends along a length of the crotch zone and has spaced apart ends that terminate at spaced apart locations of the crotch zone. The second flap also ,~, ,~ .~, has an elongated bottom in the general shape of a bow and an elongated top edge that is substantially in a straight line. The second flap also has a height (H) which is greatest at its midpoint and which progressively and gradually decreases in height in both directions from the midpoint towards its spaced apart ends. Still further, the second flap has a second elastic member in a stretched condition extending along the elongated top edge, wherein the length of each second flap corresponds to the length of the crotch zone and wherein each second flap is composed of portions of the topsheet and backsheet that have been folded upwardly in a general closed U-shaped configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
The disposable diaper according to the invention will be readily understood more in details from the following description made by way of example in reference with the accompanying drawings, in which:

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2~7 ~ ~7 Fig. 1 is a perspective view of a disposable diaper constructed according to the invention;
Fig. 2 is a sectional view taken along a line A-A in Fig.
l; and Figs, 3A and 3B are views similar to Fig. 2 showing alternative embodiments of second flaps.

PREFERRED EMBODIMENTS OF THE INVENTION
Figs. 1 and 2 illustrate a disposable diaper 1 in a perspective view and in a sectional view taken along a line A-A in Fig. 1, and Fig. 1 particularly illustrates a state in which the diaper 1 is curved toward the topside due to contraction of elastic members 13, 18 as will be described later. The diaper 1 basically comprises a liquid-permeable topsheet 2, a liquid-impermeable backsheet 3, and an absorbent core 4 sandwiched between these sheets 2, 3. The portions of said top- and backsheets 2, 3 extending beyond transversely opposite side edges 5 of the absorbent core 4 form first flaps 6 horizontally extending around respective leg-openings and second flaps 7 lying inside the respective first flaps 6 and adapted to rise on the topside of the diaper 1. The diaper 1 is longitudinally composed of front and back bodies 10, 11, and a crotch zone 12 extending between these 2 1 ~ ~ ~ 4 7 front and rear bodies 10, 11. The first flaps 6 respectively contain said elastic members 13 having their intermediate sections extending along the longitudinal dimension for the crotch zone 12. The front and rear bodies 10, 11 are provided along their longitudinally opposite ends 15, 16 with elastic members 15A, 16A, respectively. These elastic members 13, 15A, 16A are interposed between the top- and backsheets 2, 3 and intermittently bonded under tension to one of these sheets. The second flaps 7 contain in their top edges 17 said elasticmembers18 intermittentlybondedunder tensionto the backside of the backsheet 3. The rear body 11 is provided on transversely opposite side edges with tape fasteners 20, respectively, each being bonded at one end thereof to the respective side edges.
In such an arrangement, the second flaps 7 are provided within a necessary extent defined 30mm or more inside the longitudinally opposite ends 15, 16 of the front and rear bodieslO, 11, andhavetheir intermediatesections extending along the longitudinal dimension of the crotch zone 12. Each of the second flaps 7 is defined by a top edge 17 linearly connecting longitudinally opposite ends 21, 22 thereof under contraction of the elastic member 18 and a bottom edge 19 connecting said ends 21, 22 in a curved line. Said ends 21, 2 ~ 7 22 substantially correspond to the points at which the ends 18A, 18B of the elastic member 18 are bonded to the backsheet 3. The top- and backsheets 2, 3 are folded along the elastic member 18 toward the backside so as to form a fold having said top edge 17, and inner surfaces of this fold, i.e., areas of the backsheet 3 opposed to each other are intermittently bonded together. The second flap 7 rises along said bottom edge 19 on the topside of the diaper as the elastic member 18 contracts and a distance between the top and bottom edges 17, 19 is a projecting height H of the second flap 7 in such a rising state.
To obtain these second flaps 7, the elastic members 18 are bonded under tension to the backside of the backsheet 3 having no slack and then the elastic members 18 are contracted by an appropriate amount so that the diaper 1 is slackened like a bow with the elastic members 18 forming strings. After such a slackening, the top- and backsheets 2, 3 are folded along the full lengths of the respective elastic members 18 extending between the opposite ends 18A, 18B
toward the backside by a width h (not shown) with the top edges defined by the respective elastic members 18 and the areas of the backsheet 3 opposed to each other are bonded together. Bonding the elastic members 18 to the backsheet 3 2:~7 7'~ 7 and bonding the areas of the backsheet 3 to each other are preferably made in an intermittent fashion in order to facilitate the elastic members 18 to contract easily. The width h of each fold corresponds to the height H of each second flap 7 and a location of the bottom edge 19 relative to the top edge 17 is determined in such a manner that the dimension h progressively increases from the minimum at the opposite ends 18A, 18B to the maximum at the middle of the crotch zone 12. In this way, the second flaps 7 can rise on the topside of the diaper 1 as the diaper 1 is slackened in a bow-shape and have their projecting heights gradually decreasing from the maximum at the middle of the crotch zone 12 longitudinally toward the front and rear bodies 10, 11, respectively.
Referring to (A) and (B) of Fig. 3, alternative embodiments of the second flaps 7 which are distinguished from that of Fig. 2 are illustrated in views similar to Fig.
2. Referring to (A), the elastic members 18 are interposed between the top- and backsheets 2, 3 and intermittently bonded to at least one of these sheets 2, 3. Referring to (B), on the other hand, the topsheet 2 is relatively narrow and terminates inside the respective second flaps 7, i.e., the second flaps 7 are formed only by the backsheet 3.

21G7 7~7 Besides the second flaps 7 may be formed by any one of the top- and backsheets 2, 3. While the opposed areas of the backsheet3 areillustrated ascloselycontactingeachother, these opposed areas may be gradually spaced from each other toward the bottom edges 19 due to the intermittent bonding.
Referring to Fig. 1, portions of the top- and backsheets 2, 3 which extend outward beyond the periphery of the absorbent core 4 are water-tightly bonded to each other around the absorbent core 4. The topsheet 3 may be made of nonwoven fabric or porous plastic film, the backsheet 3 may be made of plastic film and the absorbent core 4 may be of fluff pulp, a mixture of fluff pulp and superabsorbant polymer, or the like. Attaching and bonding in making the diaper 1 may be achieved by utilizing adhesive such as hot melt type adhesive, sticky glue, heat sealing technique, or the like.
According to the invention, a diaper is provided with flaps longitudinally limited within a necessary extent so that theirintermediatesections extendalong the crotchzone and adapted to rise on the topside of the diaper as it is put on a wearer so that these flaps have the maximum heights at the middle of the crotch zone in which a quantity of excreted body fluids is apt to gather. Such an arrangement solves the 2~07 j l7 problem that the portions of the diaper lying adjacent the waist line become bulky and stiffy, causing a wearer to feel uncomfortable, without loss of a body fluids damming effect.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A disposable diaper comprising:
(A) a liquid-permeable topsheet having two spaced apart end portions and two spaced apart lateral sides, (B) a liquid-impermeable backsheet having two spaced apart end portions and two spaced apart lateral sides, (C) an absorbent core sandwiched between said topsheet and said backsheet, said absorbent core having two spaced apart sides that are generally parallel said lateral sides of said topsheet and said lateral sides of said backsheet at a spaced distance inwardly from said lateral sides of said topsheet and said backsheet, (D) a front body portion, a rear body portion and a crotch zone intermediate said front body portion and said rear body portion, (E) two spaced apart laterally extending first flaps formed from said topsheet and said backsheet, said first flaps extending along said crotch zone and being located lateral outwardly with respect to each said side of said absorbent core and being located generally parallel to said sides of said absorbent core, (F) elastic members mounted under tension in each of said first flaps between said topsheet and said backsheet, (G) two spaced apart second flaps, each second flap:
(a) being located intermediate one of said side of said absorbent core and the adjacent first flap, (b) extending upwardly in a generally upstanding position which is generally at a right angle to a horizontal plane of said absorbent core, (c) extending along a length of said crotch zone, (d) having spaced apart ends that terminate at spaced apart locations of said crotch zone, (e) having an elongated bottom in the general shape of a bow and an elongated top edge that is substantially in a straight line, (f) having a height (H) which is greatest at its midpoint and which progressively and gradually decreases in height in both directions from said midpoint towards its spaced apart ends, and (g) a second elastic member in a stretched condition extending along said elongated top edge, wherein the length of each second flap corresponds to the length of said crotch zone, and wherein each second flap is composed of portions of said topsheet and backsheet that have been folded upwardly in a generally closed U-shaped configuration.