CA2180631C

CA2180631C - Disposable absorbent pants type undergarment

Info

Publication number: CA2180631C
Application number: CA002180631A
Authority: CA
Inventors: Toshifumi Otsubo; Hiroyuki Soga
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 1995-07-14
Filing date: 1996-07-05
Publication date: 2000-08-01
Anticipated expiration: 2016-07-05
Also published as: EP0753292B1; AU712652B2; AU712652C; US5916206A; KR970005251A; DE69627248T2; AU5615196A; EP0753292A3; DE69627248D1; CA2180631A1; EP0753292A2; TW338942U

Abstract

In a diaper as one embodiment of a disposable absorbent undergarment according to the invention, the diaper is provided around a front region thereof with a plurality of elastic elements. The number of the elastic elements arranged in an area defined by respective vertical widths of 10mm above and below a front edge of an absorbent core disposed between a topsheet and a backsheet is greater than that of the elastic elements in the remaining area of the front region. An elongation stress of the elastic elements in the area mentioned firstly is lower than that of the elastic elements in the area mentioned lastly.

Description

DISPOSABLE ABSORBENT PANTS TYPE UNDERGARMENT
Field of the Invention The present invention relates to pants type disposable absorbent undergarments such as pants type disposable diapers for babies, incontinent pants, training pants for babies and the like.
Background of the Invention io In conventional pants type absorbent undergarments, a waist-opening and a pair of leg-openings are usually provided with respective elastic members to impart the respective opening edges with a desired stretchability in the circumferential direction. The elastic ~5 elements associated with the waist-opening are usually arranged over a fairly large region defined between an edge of the waist-opening and a crotch region extending between the waist-opening and leg-openings.
These elements exert a pressure upon a portion of the undergarment overlying a liquid-absorbent core to thereby bring an inner side of this 2 o portion tightly against the wearer's body. Such an undergarment is disclosed, for example, in Japanese Laid-Open Patent Application Nos.
Hei4-166150 and Hei4-289201.
Summary of the Invention Attempts to bring the desired portion of the undergarment overlying the liquid-absorbent core tightly against the wearer's body and thereby to avoid leakage of body fluids disadvantageously causes the elastic elements to compress the wearer's waist over a wide range.

3 o This can make an undergarment uncomfortable to wear.
A

~~80631 .2.
Surprisingly, it has been found that leakage of body fluids can be effectively avoided by bringing only a local area overlying the longitudinally opposite edges of the core rather than the entire portion overlying the core closely against the wearer's body and thus the uncomfortable feeling referred to above can be alleviated.
Accordingly, a principal feature of the invention is the provision of a disposable pants type absorbent undergarment having elastic elements associated with the waist. The elastic elements are ~o arranged in a region adjacent each of longitudinally opposite edges of the core with a relatively high density so that a fit of said region to the wearer's skin may be at least partially improved.
According to the invention, there is provided a disposable 15 pants type absorbent undergarment comprising a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core disposed therebetween. The undergarment having a front region, a rear region and a crotch region extending therebetween. A plurality of elastic elements extending around a waist portion and around a pair of 2 0 leg-openings, respectively of the undergarment. In accordance with the invention, the core longitudinally extends longitudinally into the front and rear regions and has front and rear edges spaced apart from each of the waist-opening edges of the front and rear regions, respectively.
The elastic elements associated with the front region are arranged 25 between the front edge of the core and the waist-opening edge of the front region and between the front edge of the core and the crotch region. The number of the elastic elements arranged in a first area defined by respective vertical widths of lOmm above and below the ~~80631 front edge of the core being greater than that of the elastic elements arranged in a second area of the front region excluding the first area and, an elongation stress of each of the elastic elements in the first area is lower than that of the elastic elements in the second area.
According to the present invention, there is also provided a disposable absorbent undergarment wherein the elastic elements associated with the rear region are arranged between the rear edge of the core and the waist-opening edge of the rear region and between the rear edge of the core 1 o and the crotch region. The number of elastic elements arranged in a third area defined by respective vertical widths of 1 Omm above and below the rear edge of the core is greater than that of the elastic elements arranged in a fourth area of the rear region excluding the third area, and an elongation stress of each of the elastic elements in the third area is lower than that of the elastic elements in the fourth area.
With the disposable absorbent undergarment constructed as described above, the portion of the undergarment overlying the area defined by the front edge of the core and adjacent thereto has a comfortable fit to the 2 o wearer's body without exerting a relatively high pressure, since the elastic elements associated with the front region are arranged in this area with a relatively high density, but with a relatively lower elongation stress.

- ~~80831 Brief Description of the Drawing Fig. 1 is a partially broken away perspective view showing a pants type diaper according to the invention; and, Fig. 2 is a sectional view taken along a line II-II in Fig. 1.
Detailed Description of the Preferred Embodiment of the Invention 1 o Referring to Fig. 1, a diaper comprises a liquid-permeable topsheet 2, a liquid-impermeable backsheet 3 and a liquid-absorbent core 4 disposed between these two sheets 2, 3 and further comprises a front region 5, a rear region 6 and a crotch region 7 extending between these two regions 5, 6 as viewed longitudinally of the diaper 1. The topsheet 2 and backsheet 3 are bonded together at their portions extending outward beyond a peripheral edge of the core 4 and the front and rear regions 5, 6 have their inner surfaces opposed to each other bonded together along their transversely opposite edges at intermittently provided adhesive spots 10 to define a waist-opening 1 l and a pair of leg-openings 12 and thereby to configure the diaper 1 as a 2 o whole in the form of a pants (or briefs)-shape. In the diaper 1, the core extends longitudinally over the crotch region 7 into the front and rear regions 5, 6, and has a front edge 4A, a rear edge 4B and transversely opposite edges 4C. The diaper 1 is provided around at least the front region 5 with a first elastic member 15 and around each leg-opening with a second elastic member 2 5 16. The first and second elastic members 15, 16 are secured in a stretched condition to an inner surface of at least one of the topsheet 2 and backsheet _ ~18~s3 ~
3 so that a number of gathers are formed around the waist and the legs as these elastic members 15, 16 contract. The second elastic member 16 comprises a group 17A of elastic elements 16a.
Referring to Fig. 2, the core 4 has a thickness which is substantially uniform over the front region 5 but, over an area of at least 1 Omm wide adjacent the front edge 4A, is progressively reduced toward the front edge 4A. Such locally reduced thickness may be obtained either by reducing the core material progressively toward the front edge 4A or by 1 o compressing the core material in the front edge area. The portions of the topsheet 2 and backsheet 3 extending outward beyond the front edge 4A are bonded together by means of hot melt adhesive (not shown) to form a waist-opening edge 22. The rear region 6 is also constructed in a manner substan-dally similar to that shown in Fig. 2.
Referring again to Figs. l and 2, the first elastic member 15 comprises a group 17B3 of elastic elements 15a extending along the opening edge 22, a group 17B1 of elastic elements 15b extending adjacent the front edge 4A of the core 4 and a group 17B2 of elastic elements 15c extending 2 o below the group 17B1 of elastic elements 15b. Each elastic element 15a of group 17B3 is 0.5 to 3mm wide, 0.05 to 1.5mm thick. The average density of elastic elements 15a in group 17B3 is less than two point three (2.3)per 1 Omm unit of vertical width. Each elastic element 15b of the group 17B1 is 0.1 to 1.5mm wide and 0.05 to 1.5mm thick. The average density of elastic elements 15b in region 17B1 above and below the front edge 4A is two point five (2.5) per l Omm unit of vertical width. Each elastic element 15c of the group 17B2 _~..~_w__._._._ _ _~...

_6_ 218 Q6 3 1 is 0.1 to 5mm wide and 0.05 to 1.5mm thick. The average density of elastic elements 15c in the group 1782 is two (2.0) per l Omm unit of vertical width.
The elastic elements 15b, 15c of the groups 1781 and 1782 intersecting the core 4 are bonded to the backsheet 3 so that they may be distributed on an s outer surface of the core 4. The elastic elements 15a, 15b, 15c of the groups 1783, 1781 and 1782 are secured to the backsheet 3 with a 50% elongation stress per 150mm of 5 to 50g and an elongation ratio of 1.1 to 2.5. The second elastic member 16 comprises a group 17A of elastic elements 16a.
The elongation stress of each of the elastic elements 15b of the group 1781 1 o is lower than that of each of the elastic elements 15a, 15c of the groups 1783, 1782.
With the diaper 1 constructed as described above, the core 4 closely fits the wearer's skin at the front edge 4A and an area adjacent 15 thereto, since the elastic elements 15b of the group 178, are densely arranged above and below the front edge 4A of the core 4. Consequently, even if a portion of discharged body fluids flows on an upper surface of the topsheet 2 without being absorbed by the core 4, such flow will be unable to pass through the area adjacent the front edge 4A and is therefore reliably 2 o prevented from leaking outward. In the diaper l, the elastic elements 15a of the group 1783 extend transversely across the front and rear regions 5, 6 so that they are continuous from the front region 5 to the rear region 6.
Furthermore, an area defined by the group 178, including the elastic elements 15b will not exert a greater pressure against the center zone of the wearer's 2 s abdomen compared with the groups 1783, 1782 including the elastic elements 15a, 15c, since the elongation stress of each of the elastic elements 15b of the _.

- ~~$os3 ~
group 17B1 is lower than that of each of the elastic elements 15a, 15c of the groups 17B3, 17B2. The diaper 1 will therefore be more comfortable to wear.
While the elastic elements 1 Sb, 1 Sc of the groups 17B1, 17B2 are preferably arranged both on the front region 5 and on the rear region 6, it is also possible without departing from the scope of the invention to arrange them on only one of these front and rear regions, for example, depending on the wearer's particular body form.
The elastic elements 1 Sb of the group 17B1 may be replaced by one or more relatively wide ribbon-like elastic members) to improve a fit of the core at its front edge 4A and the area therearound to the wearer's skin.
However, such replacement would be disadvantageous in that a desired air-permeation between the interior and exterior of diaper 1 will be significantly impeded.
In order to implement the invention, a nonwoven fabric or perforated plastic film may be used for the topsheet 2 and a plastic film such as polyethylene may be used for the backsheet 3. Fluff pulp alone or a mixture of fluff pulp and superabsorptive polymer powder may be molded by 2 o any well known technique into a shape required for the core 4. A material having a rubber-like elasticity such as rubber or a plastic elastomer may be used for the first and second elastic members 15, 16.
With the undergarment of the invention, the undergarment 2 5 reliably fits the wearer's body as described above and can prevent body fluids from leaking beyond the front edge without causing the wearer to be - ~~8A631 uncomfortable. Furthermore, progressive reduction of thickness of the core adjacent the front and/or rear edges(s) is effective to reduce a difference in level generated between the core and the wearer's skin and thereby to improve a wearing appearance. Even if such progressive decrease in the core s thickness is obtained by compressing the core material, the densely arranged elastic elements allow such progressively thinned area to fit the wearer's body.

Claims

1. A disposable absorbent pants type undergarment pants type comprising a liquid-permeable topsheet, a liquid-impermeable backsheet joined to the topsheet and a liquid-absorbent core disposed therebetween, said undergarment having a front region, a rear region and a crotch region extending therebetween, and a plurality of elastic elements extending around said front and rear regions and around a pair of leg-openings, respectively, wherein the improvement comprises:

said core extending longitudinally into said front and rear regions and having front and rear edges spaced apart from a waist-opening edge of each of said front and rear regions, respectively;

said elastic elements associated with said front region being arranged between the front edge of said core and the waist-opening edge of said front region and between the front edge of said core and said crotch region, the number of said elastic elements arranged in a first area defined by respective vertical widths of 10mm above and below the front edge of said core being greater than that of said elastic elements arranged in a second area of said front region excluding said first area, an elongation stress of each of said elastic elements in said first area being lower than that of said elastic elements in said second area.

2. The undergarment according to claim 1, wherein, in an area of said core at least 10mm inward from the front edge of said core, said core has a thickness progressively reduced toward said front edge.

3. The undergarment according to claim 1, wherein said elastic elements associated with said rear region are arranged between the rear edge of said core and the waist-opening edge of said rear region and between the rear edge of said core and said crotch region, the number of said elastic elements arranged in a third area defined by respective vertical widths of 10mm above and below the rear edge of said core is greater than that of said elastic elements arranged in a fourth area of said rear region excluding said third area, and an elongation stress of each of said elastic elements in said third area is lower than that of said elastic elements in said fourth area.

4. An absorbent undergarment comprising:
(a) a liquid-permeable topsheet extending between a waist opening edge and a crotch region;
(b) a liquid-impermeable backsheet disposed outwardly from said topsheet;
(c) a liquid-absorbent core disposed between said topsheet and said backsheet said core extending downwardly from a top edge below said waist opening; and, (d) a plurality of generally transverse elastic elements arranged outwardly from said core between said crotch region and said waist opening edge to bias said core inwardly against a wearer's body;
wherein said elastic elements are arranged more densely in a first strip extending 10mm above and below said top edge of said core than in a second strip at least 10mm wide extending below and adjacent said first strip and wherein said elastic elements in said first strip have an elongation stress lower than an elongation stress of said elastic elements in said second strip.

5. The absorbent undergarment of claim 4 wherein said core is tapered in thickness toward said top edge.