U.S. patent application number 11/235538 was filed with the patent office on 2006-04-27 for underpants-type disposable diaper.
This patent application is currently assigned to UNI-CHARM CORPORATION. Invention is credited to Kyota Saito.
Application Number | 20060089615 11/235538 |
Document ID | / |
Family ID | 36142588 |
Filed Date | 2006-04-27 |
United States Patent
Application |
20060089615 |
Kind Code |
A1 |
Saito; Kyota |
April 27, 2006 |
Underpants-type disposable diaper
Abstract
An underpants-type disposable diaper is of a size and a water
absorption capacity suitable for infants 3 to 6 years old, and is
capable of preventing the protrusion of the groin portion of the
diaper in use so that leakage does not occur. The leakage can be
avoided by increasing the size and the water absorption capacity of
the diaper main body 110 to a level suitable for infants 3 to 6
year olds still using diaper and at the same time improving the
tracks of a plurality of elastic members 170 disposed along the
peripheral edges of leg holes 130 so as to reduce the elasticity in
the vertical direction of the crotch section and prevent the
protrusion of the groin when the diaper is worn.
Inventors: |
Saito; Kyota; (Kagawa-ken,
JP) |
Correspondence
Address: |
LOWE HAUPTMAN GILMAN AND BERNER, LLP
1700 DIAGONAL ROAD
SUITE 300 /310
ALEXANDRIA
VA
22314
US
|
Assignee: |
UNI-CHARM CORPORATION
Shikokuchuo-shi
JP
|
Family ID: |
36142588 |
Appl. No.: |
11/235538 |
Filed: |
September 27, 2005 |
Current U.S.
Class: |
604/385.27 |
Current CPC
Class: |
A61F 13/496 20130101;
A61F 13/49017 20130101 |
Class at
Publication: |
604/385.27 |
International
Class: |
A61F 13/15 20060101
A61F013/15 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2004 |
JP |
2004-289868 |
Claims
1. An underpants-type disposable diaper comprising an
underpants-formed diaper main body, wherein said diaper main body
comprises an underpants-formed outer cover having a waist opening
part to be fixed to a wearer's trunk, a pair of leg holes for the
wearer's legs to pass thorough, a front part to be positioned
ventral to the wearer, a back part to be positioned dorsal to the
wearer and a crotch part jointed to said front part and said back
part to be positioned between legs of the wearer, and a
substantially belt-like inner member joined to the inner side of
said outer cover, said inner member positioned between said leg
holes; said front part comprising an elastic member pulling said
inner member in the lateral direction of said diaper.
2. The underpants-type disposable diaper according to claim 1
wherein said elastic member is a linear elastic member extending
from one side edge of said front part to the center of said front
part along the peripheral edge of each of said leg holes forming a
horizontally elongated arc.
3. The underpants-type disposable diaper according to claim 2
wherein the ratio of the minimum dimension of said elastic member
from one end positioned near the side edge of said front part to
the other end thereof positioned near the center of said front part
in the lateral direction to the minimum dimension thereof in the
vertical direction is not less than 1.0 and not more than 3.0 in a
state that said elastic member is not expanded.
4. The underpants-type disposable diaper according to claim 2,
wherein a plurality of the elastic member are provided in both
sides of said front part; and the interval between the ends of the
elastic members positioned near the center of said front part is
not less than 7 mm and not more than 12 mm in a state prior to its
wearing.
5. The underpants-type disposable diaper according to claim 3,
wherein a plurality of the elastic member are provided in both
sides of said front part; and the interval between the ends of the
elastic members positioned near the center of said front part is
not less than 7 mm and not more than 12 mm in a state prior to its
wearing.
6. The underpants-type disposable diaper according to claim 2,
wherein the maximum dimension of said disposable diaper main body
in the vertical direction is not less than 225 mm and not more than
265 mm in a state prior to its wearing, and that in the lateral
direction is not less than 180 mm and not more than 215 mm in a
state prior to its wearing.
7. The underpants-type disposable diaper according to claim 3,
wherein the maximum dimension of said disposable diaper main body
in the vertical direction is not less than 225 mm and not more than
265 mm in a state prior to its wearing, and that in the lateral
direction is not less than 180 mm and not more than 215 mm in a
state prior to its wearing.
8. The underpants-type disposable diaper according to claim 4,
wherein the maximum dimension of said disposable diaper main body
in the vertical direction is not less than 225 mm and not more than
265 mm in a state prior to its wearing, and that in the lateral
direction is not less than 180 mm and not more than 215 mm in a
state prior to its wearing.
9. The underpants-type disposable diaper according to claim 5,
wherein the maximum dimension of said disposable diaper main body
in the vertical direction is not less than 225 mm and not more than
265 mm in a state prior to its wearing, and that in the lateral
direction is not less than 180 mm and not more than 215 mm in a
state prior to its wearing.
10. The underpants-type disposable diaper according to claim 1,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700
g.
11. The underpants-type disposable diaper according to claim 2,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700
g.
12. The underpants-type disposable diaper according to claim 3,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700
g.
13. The underpants-type disposable diaper according to claim 4,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700
g.
14. The underpants-type disposable diaper according to claim 5,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700
g.
15. The underpants-type disposable diaper according to claim 6,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700
g.
16. The underpants-type disposable diaper according to claim 7,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700
g.
17. The underpants-type disposable diaper according to claim 8,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700
g.
18. The underpants-type disposable diaper according to claim 9,
wherein the water absorption capacity of said absorbent body is not
less than 800 g and not more than 1000 g, and the water-holding
capacity thereof is not less than 500 g and not more than 700 g.
Description
CROSS REFERENCE TO THE RELATED APPLICATION
[0001] Priority is claimed on Japanese Patent Application No.
2004-289868, filed Oct. 1, 2004, the content of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a leak-resistant
underpants-type disposable diaper, and specifically relates to an
underpants-type disposable diaper having a size and an absorption
capacity usable for infants of 3 to 6 years old who are still in
diapers, and capable of preventing a groin portion of the diaper
from outwardly protruding in use.
RELATED ART
[0003] Recently, the quality of disposable diaper has been
dramatically improved so that most infants wear disposable diapers.
There are two types of disposable diapers. One is a type which
opens up and has attachment tapes (tape-type), and the other is a
type underpants-shaped type (underpants-type). The tape-type
disposable diaper is to be fixed to the body with tape at two
positions around the waist, and it is intended for relatively young
babies a few months old. On the other hand, the underpants-type
diaper is integrally formed like a pair of underwear pants, can be
put on an infant while standing, and is intended for infants of 1
to 3 years old.
[0004] In general, infants are said to be out of diapers at around
the age of 2, and it is recommended to start toilet training at
this age. However, according to a recent survey in Japan, the age
at which diaper use was discontinued in the daytime was 21.4 months
old on average in 1960, but 30.5 months old on average in 2000, a
delay of approximately up to 9 months. Thus, the discontinuation of
diaper use has been delayed in recent years such that older infants
use disposable diapers. Accordingly, there has been is a steady
increase in the demand for the underpants-type disposable diaper
because the underpants-type diaper of a large size adaptable to
older infants, who have not been regarded as wearers of disposable
diapers, has been demanded.
[0005] In this respect, in the conventional underpants-type diaper,
there has been a problem in preventing fluid leakage due to the
groin portion protruding in use, and the invention disclosed in
Japanese patent number 2571282 (patent reference 1) has been cited
as one tackling this problem. According to the invention described
in this patent reference 1, an elastic member (hereinafter referred
to as "central elastic member") is provided so that the central
elastic member extends from the vicinity of a leg hole to the
vicinity of the other leg hole passing across a section of the
diaper positioned below the groin (hereinafter referred to as
"under groin section"). In other words, in the central elastic
member, both ends thereof are provided around a pair of leg holes
is disposed diagonally across the under groin section thereof such
that the under groin section can be lifted so as to closely adhere
to its corresponding part of the body. Furthermore, both ends of
the central elastic member are continuous with other elastic
members (hereinafter referred to as "side elastic members")
disposed along each of the leg holes. Therefore, the close contact
between the diaper and the body can be maintained even when the
wearer moves such as in walking, because the central elastic member
can expand and contract in conjunction with the tension and
shrinkage of these both side elastic members, However, in the
invention according to the patent reference 1, vertical movement of
the groin portion cannot be prevented, so that the problem that the
groin portion protrudes in use cannot be sufficiently avoided.
SUMMARY OF THE INVENTION
[0006] The present invention has been made in view of the
above-described problems and aims to provide an underpants-type
disposable diaper usable for infants 3 to 6 years old who are still
in diapers, and capable of preventing the groin portion from
protruding while it is worn so as to provide a leak-resistant
underpants-type diaper.
[0007] The present inventor has actively researched to solve the
aforementioned problems. As a result, the inventor found that the
groin portion can be prevented from protruding in use by careful
arrangement of a plurality of elastic members disposed along the
peripheral edges of the leg holes, thereby reducing the vertical
movement of the groin portion even when the size and the absorption
capacity of the diaper main body are increased to a level usable
for infants of 3 to 6 years old who are still in diapers, and the
inventor has achieved the present invention. More specifically, the
present invention provides the following.
(1) An underpants-type disposable diaper including an
underpants-formed diaper main body,
[0008] the diaper main body including an underpants-formed outer
cover having a waist opening part to be fixed to a wearer's trunk,
a pair of leg holes for the wearer's legs to pass thorough, a front
part to be positioned ventral to the wearer, a back part to be
positioned dorsal to the wearer and a crotch part jointed to the
front part and the back part to be positioned between legs of the
wearer, and a substantially belt-like inner member joined to the
inner side of the outer cover, the inner member positioned between
the leg holes; and
[0009] the front part has an elastic member pulling the inner
member in the lateral direction of the diaper.
[0010] In the underpants-type disposable diaper according to (1),
the arrangement of a plurality of elastic members disposed along
the peripheral edges of the leg holes is devised so as to prevent
the protrusion of the groin portion of the diaper in use.
Specifically, an elastic member pulling the inner member in the
horizontal direction is provided in the front part.
[0011] (2) The underpants-type disposable diaper according to (1)
in which the elastic member is a linear elastic member extending
from one side edge of the front part to the center of the front
part along the peripheral edge of each of the leg holes forming a
horizontally elongated arc.
[0012] According to the present invention, the elastic members are
provided in the front part and the back part and each of the
elastic members extends from the top front of a leg hole to the
bottom rear of the leg hole to form a semicircular arc. The elastic
member provided in the front part extends from the side edge of the
front part toward the center of the front part forming a
horizontally elongated arc, one end of which is positioned on the
side edge of the front part and the other end (hereinafter referred
to as "top point") is positioned near the top front of the leg
hole.
[0013] (3) The underpants-type disposable diaper according to (2)
in which the ratio of the minimum dimension of the elastic member
from one end positioned near the side edge of the front part to the
other end thereof positioned near the center of the front part in
the lateral direction to the minimum dimension thereof in the
vertical direction is not less than 1.0 and not more than 3.0 in a
state that the elastic member is not expanded.
[0014] More specifically, the ratio of the minimum dimension of the
elastic member from one end positioned at the side edge of the
front part to the top point thereof in the lateral direction to the
minimum dimension thereof in the vertical direction is not less
than 1.0 and not more than 3.0 in a state prior to its wearing,
that is to say the elastic member is not expanded. This
underpants-type disposable diaper is designed so that ratios of
these dimensions become larger compared to those in the
conventional products which are approximately 0.5 to 0.8. That is,
in this underpants-type disposable diaper, compared to the
conventional products, the dimension of the elastic members in the
vertical direction is small and the elastic member is horizontally
elongated so as to reduce the elasticity in the vertical direction
of the groin portion by pulling the groin portion in the lateral
direction. Therefore, according to this underpants-type disposable
diaper, the protrusion of the groin portion in use can be prevented
so as to avoid fluid leakage.
[0015] (4) The underpants-type disposable diaper according to (2)
or (3)
[0016] in which a plurality of the elastic member are provided in
both sides of the front part; and
[0017] the interval between the ends of the elastic members
positioned near the center of the front part is not less than 7 mm
and not more than 12 mm in a state prior to its wearing.
[0018] In the underpants-type disposable diaper according to (4),
the interval between the elastic members at the top points thereof
is not less than 7 mm and not more than 12 mm. Thus, in this
underpants-type disposable diaper, the interval between the elastic
members is designed to be wider compared to that of a conventional
underpants-type disposable diaper which is about 5 mm. This
underpants-type disposable diaper has been designed so as to avoid
so-called rubber band traces which are apt to be formed due to the
careful arrangement of a plurality of elastic members disposed
along the peripheral edges of the leg holes, increasing the
elasticity in the direction around the waist (in the lateral
direction) and at the same time to reduce the elasticity of the
groin portion in the vertical direction thereof. That is, this
underpants-type disposable diaper is able to prevent the rubber
band traces from being left on its wearing by widening the interval
between the elastic members so as to disperse the pressure exerted
on the section around the waist.
[0019] (5) The underpants-type disposable diaper according to any
one of (2) to (4) in which the maximum dimension of the diaper main
body in the vertical direction is not less than 225 mm and not more
than 265 mm in a state prior to its wearing, while the maximum
dimension thereof in the lateral direction is not less than 180 mm
and not more than 215 mm in a state prior to its wearing.
[0020] In the underpants-type disposable diaper according to (5),
the maximum dimension of the diaper main body in the vertical
direction prior to its wearing is not less than 225 mm and not more
than 265 mm while the maximum dimension thereof in the lateral
direction is not less than 180 mm and not more than 215 mm. Even in
the largest-type among the conventional products, the maximum
dimension of the diaper main body in the vertical direction is
about 215 mm and that in the lateral direction is about 175 mm.
Accordingly, this underpants-type disposable diaper is as large as
not has been observed with the conventional products, and can be
worn even by infants of 3 to 6 years old who have not been regarded
as wearers of diapers.
[0021] Furthermore, in the underpants-type disposable diaper of
such large size, the protrusion of the groin portion is apt to
become more prominent while the diaper is worn. In response, the
underpants-type disposable diaper according to (5) is able to
become more effective in preventing the protrusion of the groin
portion in its use by the arrangement of a plurality of elastic
members disposed along the peripheral edges of the leg holes so as
to reduce the expansion and contraction of the groin portion in the
vertical direction.
[0022] (6) The underpants-type disposable diaper according to any
one of (1) to (5) in which the water absorption capacity of the
absorbing body is not less than 800 g and not more than 1000 g,
while the water-holding capacity thereof is not less than 500 g and
not more than 700 g.
[0023] The absorbent body used in the underpants-type disposable
diaper according to (6) has a larger water absorption capacity and
a larger water-holding capacity than the conventional product.
Specifically, in contrast to the water absorption capacity of the
largest-sized conventional product which was about 660 g per
diaper, the water absorption capacity of the absorbent of the
underpants-type disposable diaper according to the present
invention is not less than 800 g and not more than 1000 g per
diaper. Furthermore, in contrast to the water-holding capacity of
absorbent body of the largest-sized conventional product which is
about 450 g per diaper, the water-holding capacity of the absorbent
body of the underpants-type disposable diaper according to the
present invention is not less than 500 g and not more than 700 g
per diaper. Accordingly, the underpants-type disposable diaper of
the present invention is provided with a very large water
absorption capacity so as to be sufficiently usable in infants of 3
to 6 years old whose volume of urinary excretion is high.
[0024] Further, in an underpants-type disposable diaper provided
with such large water absorption capacity, the protrusion of the
groin portion around the crotch is apt to become more remarkable in
its use. Therefore, similarly as the underpants-type disposable
diaper according to (5), that according to (6) can be more
effective in preventing the protrusion of the groin portion in its
use by devising the arrangement of a plurality of elastic members
disposed along the peripheral edges of the leg holes so as to
reduce the extension and contraction of the diaper in the vertical
direction of the groin portion.
[0025] According to the present invention, an underpants-type
disposable diaper can be provided which has a size and a water
absorption capacity usable for infants of 3 to 6 years old who are
still using diapers, and is capable of preventing the protrusion of
the groin portion in use so as to be resistant leakage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a perspective view of an underpants-type
disposable diaper according to an embodiment of the present
invention.
[0027] FIG. 2 is a plan view of the underpants-type disposable
diaper according to an embodiment.
[0028] FIG. 3 is an exploded plan view of the underpants-type
disposable diaper according to an embodiment whose side flap is
opened to separate a front part and a back part.
[0029] FIG. 4 is the underpants-type disposable diaper according to
an embodiment viewed from the flank side of a wearer in a state
soon after the diaper is worn.
[0030] FIG. 5 is the underpants-type disposable diaper according to
an embodiment in its use viewed from the flank side of a
wearer.
[0031] FIG. 6 is a perspective view of a conventional
underpants-type disposable diaper.
[0032] FIG. 7 is a plan view of the conventional underpants-type
disposable diaper.
[0033] FIG. 8 is an exploded plan view of the conventional
underpants-type disposable diaper whose side flap is opened to
separate a front part and a back part
[0034] FIG. 9 is the conventional underpants-type disposable diaper
viewed from the flank side of a wearer in a state soon after the
diaper is worn.
[0035] FIG. 10 is the state of the conventional underpants-type
disposable diaper in its use viewed from the flank side of a
wearer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] In the following, the preferred embodiments of the present
invention will be described with reference to the drawings.
[0037] Whole Constitution of Underpants-Type Disposable Diaper
[0038] FIG. 1 is a perspective view and FIG. 2 is a plan view of an
underpants-type disposable diaper 100 according to an embodiment of
the present invention. FIG. 3 is an exploded plan view of the
underpants-type disposable diaper 100 according to this embodiment
in which the side flap 190 is opened to separate a front part 101
and a back part 102. Furthermore, as a reference, a perspective
view of a conventional underpants-type disposable diaper 300 is
shown in FIG. 6, a plan view thereof in FIG. 7, and an exploded
plan view thereof when the side flap 390 is opened) to separate a
front part 301 and a back part 302 in FIG. 8. The underpants-type
disposable diaper 100 according to this embodiment is wearable by
infants of 3 to 6 years old, and is provided with an underpants
formed diaper main body 110. The maximum dimension of the diaper
main body 110 before it is worn is not less than 225 mm and not
more than 265 mm in the vertical direction, and is not less than
180 mm and not more than 215 mm in the lateral direction.
Diaper Main Body
[0039] The diaper main body 110 includes an underpants formed outer
cover 140 having a waist opening part 120 to be fixed to the trunk
of a wearer and a pair of leg holes to be fixed to the legs of the
wearer, and a substantially belt-like inner member 150 joined to
the inner side of the outer cover 140, the inner member 150 extends
from the ventral side (front side) to the dorsal side (back side)
of the diaper main body 110 passing through between the leg holes
130. The outer cover 140 is formed by assembling a front part 101
to be positioned ventral to the wearer, a back part 102 to be
positioned to dorsal to the wearer and a crotch part 103 which is
joined to one edge of the front part 101 and one edge of the back
part 102 and positioned between the legs of the wearer. In order to
assemble the outer cover 140 and the inner member 150, heat
sealing, ultrasonic sealing, hot-melt adhesives, and the like can
be used. In addition, the diaper main body 110 is provided with a
plurality of elastic members 170 extending in curves along the
peripheral edges of each of the leg holes 130 toward the back part
102 from the front part 101 through the top side of the leg hole
130.
[0040] The diaper main body 110 is provided with the elastic cords
107 which are elastic at parts of the front part 101 and can be the
back part 102 thereof, and put on a wearer in a state where these
elastic cords 107 are pulled so as to closely adhere to the
wearer's body. The diaper main body 110 is also provided with a
plurality of waist bands 109 which are formed of elastic material
extending along the waist opening part 120. The waist bands 109 are
substantially parallel to the edge of the waist opening part 120.
The elastic cords 107 are provided on both sides of the front part
101 and the back part 102 extending substantially straight in the
lateral direction of the diaper main body 110 to be parallel to the
waist bands 109. The elastic cords 107 and the waist bands 109 are
disposed among a plurality of sheets constituting the outer cover
140, and joined in an extended state between the two sandwiching
sheets by hot-melting. Furthermore, the side flaps 190 are provided
on both sides of the diaper main body 110, each of the side flaps
190 is formed by joining one side edge of the front part 101 and
one side edge of the back part 102. Each of the side flaps 190 has
a fastening tape 195 to be used when the diaper 100 is worn, and
designs or the like may be indicated on the front part 101 and the
back part 102.
Outer Cover
[0041] The outer cover 140 has at least one sheet forming the
outward form of the diaper main body 110. As these sheets, to
ensure liquid containment, softness and comfortableness to the skin
and breathability, non-woven fabric sheets such as span-bond
non-woven fabrics, through-air non-woven fabrics composed of fibers
of polyethylene, polypropylene, polyethylene terephthalate or the
like, span-lace non-woven fabric, and composite sheets formed with
an elastic and extensible non-woven fabric containing elastomer and
copolymer and an elastic film may be used. Furthermore, a
water-impermeable plastic film or a multi-ply sheet of these films
can be also used. In this case, the breathability and moisture
permeability of the plastic films can be ensured by extending them
after mixing with fillers.
[0042] As the non-woven fabrics, non-woven fabrics formed with
sheath-core-type composite fibers formed from fibers of polyolefin,
polyester, polyamide and such, or a side-by-side-type composite
fiber can be used. The method for manufacturing a non-woven fabric
is not restricted, and span-bond, point-bond, through-air bond,
chemical bond, melt-blown, span-lace and needle-punch methods can
be used for example. In this case, the fiber diameter of a fiber
used for a non-woven fabric is preferably 0.1 .mu.m to 50 .mu.m,
more preferably 5 .mu.m to 30 .mu.m. The specific weight per unit
area of non-woven fabrics is preferably 2 g/m.sup.2 to 100
g/m.sup.2, more preferably 7 g/m.sup.2 to 20 g/m.sup.2.
[0043] Furthermore, the outer cover 140 of the present embodiment
has a liquid-impermeable back sheet. The back sheet prevents
excretions once absorbed into an absorbent core from leaking to the
outside. As the back sheet, a water-repellent non-woven fabric,
moisture-permeable plastic film having minute pores or laminates
thereof can be used. It is possible to reduce the stuffy feeling
and dissipate the uncomfortable feeling when fixing a diaper by
using moisture-permeable materials as the back sheet. As a material
used for a moisture-permeable sheet, a membranous sheet-like film
made of synthetic plastic and a breathable film obtained by filling
up a synthetic plastic with a filler and subjecting it to a
stretching treatment, a composite laminate formed of a paper and a
non-woven fabric, a breathable blocking sheet with a 10% to 30%
aperture ratio obtained by arranging capillaries having a pore
diameter in the range of 0.1 mm to 0.6 mm opposing toward the
absorbing body side or the like can be used. A thermoforming film
embossed to confer a fabric-like outward appearance thereon is
preferable.
Inner Member
[0044] The inner member 150 has an absorbent body 180 composed of
an absorbent core and a liquid-permeable surface side sheet. The
water absorption capacity and the water-holding capacity of the
absorbing body 180 per diaper are 900 g and 600 g respectively,
such that it has a more excellent absorption capacity than
conventional products.
[0045] As a surface side sheet, a material which is not irritating
to the skin is preferable, and liquid-permeable sheets such as
hydrophilic non-woven fabric and porous plastic are used. Non-woven
fabrics cited herein are those manufactured by the span-bond,
span-lace, needle-punch, melt-blown, thermal bond, chemical bond,
air-through methods, etc. As a non-woven fabric, the one similar to
that for the outer cover 140 can be used. Furthermore, rayon,
acetate, cotton, pulp or synthetic resin is used alone or as a
composite fibrous sheet by combining them so as to form a
core-sheath structure.
[0046] As an absorbent core one in which a fibrillated pulp and a
super absorbent polymer are jointly employed is preferably used. In
addition, absorbent cores in which cellulosic fibers, thermoplastic
resin, super absorbent polymer, thermal bonding fibers and such are
mixed and heat-treated are preferably used. The absorbent core can
be formed by laminating the material mentioned above. In the case
of an absorbent core having a plurality of layers, the super
absorbent polymer may be disposed at any one of the upper, middle
and lower layers, and it may be mixed with pulp to be disposed at
any one of the upper, middle and lower layers. A super absorbent
polymer is preferably the one capable of absorbing and retaining a
liquid more than twenty times its own weight and having a property
to become gelled. Examples of such super absorbent polymer are
starch-acrylate (salt) graft copolymer, hydrolyzates of
starch-acrylonitrile copolymer, cross-linked products of sodium
carboxymethyl cellulose, acrylate (salt) polymer, etc.
Elastic Member
[0047] The plural elastic members 170 are disposed along each of
the peripheral edges of the leg holes 130 so as to extend in curves
from the front part 101 to the back part 102 through the top side
of the leg holes 130. The elastic members are provided in both the
front part 101 and the back part 102, and each of the elastic
member 170 extends from the top front of the leg hole 130 to the
bottom rear of the leg hole 130 to form a substantially
semicircular arc viewed from the side of the diaper 100 as shown in
FIG. 4. The arrangements of the elastic members 170 provided in
both sides of the front part 101 are devised in the present
invention. Specifically, the elastic membersl70 are provided in the
front part 101 so that they extend from the side edge of the front
part 101 toward the center of the front part 101 forming into
horizontally elongated arc as shown in FIG. 2. One end of the
elastic member 170 of the front part 101 is positioned near the
side edge of the front part 101, and the other end (top point) of
the elastic member 170 of the front part 101 is positioned near the
joint portion joining the front part 101 and the crotch part
103.
[0048] More specifically, each of the elastic members 170 are
provided at an area in which the ratio of the minimum dimension in
the lateral direction from one end positioned at the side of the
front part 101 to the top point of the elastic member 170 to the
minimum dimension in the vertical direction is not less than 1.0
and not more than 3.0 in a state prior to wearing the diaper. That
is, in FIG. 2, a plan view of the underpants-type disposable diaper
100 according to this embodiment, the value X/Y, which is the ratio
of the minimum dimension X in the lateral direction from the end
part of the front part 101 to the top point of the elastic member
170 to the minimum dimension Y in the vertical direction is within
the range of not less than 1.0 and not more than 3.0.
[0049] In contrast to this, in a conventional underpants-type
disposable diaper 300 as shown in FIG. 7, an elastic member 370
extends from the bottom front of a leg hole 330 toward the bottom
rear of the leg hole forming into substantially circular arc as
shown in FIG. 9. In particular, an elastic member (upper elastic
member) 370u positioned mainly in a front part 301 and an elastic
member (lower elastic member) 370b positioned mainly in a crotch
part 303 are provided on the front side of the diaper 300. Each of
the upper elastic members 370u extends from the upper groin portion
positioned above the groin portion to the side of the front part
301, while each of the lower elastic members 370b extends from the
lower groin portion positioned around the groin portion to the
front part 301, and the top point of the upper elastic member 370u
crosses one end of the lower elastic member 370b near the end of
the front part 301. The value of the ratio X'/Y', the minimum
dimension X' in the lateral direction to the minimum dimension Y'
in the vertical direction from the crossing point of these elastic
members to the other end of the upper elastic member 370u is in the
range of 0.5 to 0.8. Thus, as is obvious from comparison of FIGS. 2
and 6, in the underpants-type disposable diaper 100 according to
this embodiment, the elastic member 170 in the vertical direction
is smaller in dimension than the conventional underpants-type
disposable diaper 300 so that the elasticity thereof in the
vertical direction above the groin portion is reduced.
[0050] As the elastic members 170, various materials such as rubber
strings, flat rubber belts and rubber ribbon made of natural
rubber, synthetic rubber and polyurethane, heat-shrinkage
materials, and water-absorbent shrinkage fibers can be used, but
are not particularly limited as long as they are sufficiently
elastic. In this case, the intervals between the elastic members
170 at the top points thereof are not less than 7 mm and not more
than 12 mm in a state prior to wearing the diaper, such that they
are designed to be wider compared to the conventional products.
Water Absorption Capacity and Water-Holding Capacity
[0051] The "water absorption capacity" in the present invention
refers to the maximum amount of water absorbable with the absorbent
body, specifically to the amount of water maintainable therein when
a 10 kg load is applied thereto. The "water-holding capacity" in
this invention refers to the maximum amount of the absorbed water
maintainable by the absorbent body, specifically to the amount of
water maintainable therein when the absorbent body is dehydrated
after centrifugation at 75 G. The water absorption capacity and
water-holding capacity per diaper can be obtained by the following
measuring methods.
[0052] First, a physiological saline (0.9% NaCl solution), an
acrylic plate (320 mm.times.545 mm in the standard dimension, 3
mm.about.5 mm in thickness, 400 g to 600 g in weight), two weights
each of 5 kg weights, a dehydrator (75 G) and a wire net (standard
wire net: 5 mm in pore diameter, 5 mm in distance between pores)
are prepared as the tools and reagent to be used.
[0053] Next, samples of the object to be measured were collected.
Specifically, after a piece of diaper was weighed, waist bands
forming waist gathers (WG), elastic members forming leg gathers
(LG) and elastic cords forming lateral side gather (LSG) were cut
to flatten the diaper. When cutting the diaper, it is necessary to
be cautious so as not to cut into the absorbent body. In this case,
the number of samples to be prepared was fixed at 5 (n=5).
[0054] As a first procedure, the absorbent body of a diaper was
immersed faced downward into about 20 litters of a physiological
saline while pressing the diaper down with the hand. The
physiological saline can be used for measuring up to 6 pieces of
diaper, but is required to be replaced with a fresh one for
measuring more than 6 pieces of samples due to the resulting
concentration changes. After the diaper was immersed, it was left
as it was for 30 minutes. After a lapse of 30 minutes, the diaper
was taken out, mounted on a wire net with the absorbent body facing
downward, and covered with the acrylic plate. Furthermore, two 5 kg
weights were mounted on the acrylic plate so as to apply a 10 kg
load in total, and the diaper was left with the loaded state for 20
minutes. After 20 minutes, the diaper was weighed, and the water
absorption capacity was obtained from the difference between the
weight after the application of the weight load and the initial
weight of the diaper.
[0055] Next, the diapers (up to 3 pieces) treated as described
above to measure the water absorption capacity were placed in a
dehydrator with the absorbent bodies facing outward such that
diapers were arranged not lying on one another and were dehydrated
by centrifugation at 75 G for 90 second. After the dehydration, the
diapers were weighed, and the water-holding capacity was obtained
from the difference between the weight after the dehydration and
the initial weight of the diaper.
Protrusion of the Groin Portion while the Diaper is Worn
[0056] The states of the underpants-type disposable diaper 100
according to this embodiment viewed from the side of a wearer soon
after it is put on (hereinafter referred to as "beginning of use")
and after for a prolonged period (hereinafter referred to as "in
use") are shown in FIGS. 4 and 5. Similarly, the states of the
conventional underpants-type disposable diaper 300 viewed from the
side of a wearer at the beginning of use and in use are shown in
FIGS. 9 and 10. As is obvious from these figures, in the
conventional underpants-type disposable diaper 300, it can be
clearly confirmed that the section around the groin B is protruded
after the diaper has absorbed fluid. In contrast, in the
underpants-type disposable diaper 100 according to this embodiment,
not much difference in its state has been observed even after it
has absorbed fluid, such that it can be confirmed that the
protrusion of the section around the groin A is prevented.
* * * * *