U.S. patent application number 09/997690 was filed with the patent office on 2002-03-21 for disposable underpants and method of continuously producing the same.
This patent application is currently assigned to Toyo Keizai Kabushiki Kaisha. Invention is credited to Matsuura, Iwao, Uchimoto, Kenichi.
Application Number | 20020035355 09/997690 |
Document ID | / |
Family ID | 14208324 |
Filed Date | 2002-03-21 |
United States Patent
Application |
20020035355 |
Kind Code |
A1 |
Uchimoto, Kenichi ; et
al. |
March 21, 2002 |
Disposable underpants and method of continuously producing the
same
Abstract
Disposable underpants 1 according to the invention has an
improved sealability at the crotch of user by providing a fitting
elastic member 55 and has an absorbent core 7 having an improved
shape retention by providing a first nonwoven fabric 73 as an
intermediate layer inside the absorbent core 7 and adhering it to
the upper and lower layers thereof. Since the absorbent core needs
not be heated, inexpensive disposable underpants can be produced.
Further, according to an inventive production method, a step of
adhering elastic members to an outer sheet 2 and a step of
producing inner absorbent members 6 are separately performed, and
no heating treatment is performed in the absorbent core production
step. Accordingly, the disposable underpants can be produced at a
remarkably higher speed.
Inventors: |
Uchimoto, Kenichi;
(Kobe-shi, JP) ; Matsuura, Iwao; (Osaka-shi,
JP) |
Correspondence
Address: |
JORDAN AND HAMBURG LLP
122 East 42nd Street
New York
NY
10168
US
|
Assignee: |
Toyo Keizai Kabushiki
Kaisha
|
Family ID: |
14208324 |
Appl. No.: |
09/997690 |
Filed: |
November 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09997690 |
Nov 29, 2001 |
|
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09490289 |
Jan 20, 2000 |
|
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09490289 |
Jan 20, 2000 |
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PCT/JP98/02402 |
May 29, 1998 |
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Current U.S.
Class: |
604/385.29 ;
604/366; 604/368; 604/385.24; 604/385.27 |
Current CPC
Class: |
A61F 13/496 20130101;
A61F 13/15699 20130101 |
Class at
Publication: |
604/385.29 ;
604/385.24; 604/385.27; 604/366; 604/368 |
International
Class: |
A61F 013/15; A61F
013/20 |
Claims
What is claimed is:
1. Disposable underpants having one waist-opening and a pair of
leg-openings, having elastic members provided near the edges of the
waist- and leg-openings and having the opposite sides thereof
bonded, comprising: an outer sheet and an inner absorbent member,
wherein: the outer sheet is provided with a waist elastic member,
leg elastic members and a fitting elastic member provided between
the waist elastic member and the leg elastic members, the fitting
elastic member being comprised of a plurality of thread-like
elastic materials in parallel with the waist elastic member, the
inner absorbent member includes a permeable top sheet, an
impermeable back sheet and an absorbent core accommodated between
the top and back sheets, and the absorbent core includes an upper
layer made of a mixture of pulp fibers and super absorbent polymer
particles, an intermediate layer provided with a first nonwoven
fabric, and a lower layer made of a mixture of pulp fibers and
super absorbent polymer particles, the intermediate layers being
adhered to the upper and lower layers by an adhesive.
2. Disposable underpants according to claim 1, wherein the
absorbent core further includes a second nonwoven fabric located
below the lower layer thereof, and a tissue located above the upper
layer thereof, the second nonwoven fabric being adhered to the
lower layer and a portion of the second nonwoven fabric projecting
out from the outer periphery of the lower layer is turned up onto
the lower layer and adhered while being placed to the first
nonwoven fabric.
3. Disposable underpants according to claim 2, wherein the upper
layer of the absorbent core is formed larger than the lower layer
thereof, the upper layer is formed to have a substantially
sandglass-shape having narrowed portions at the left and right
sides of a middle portion with respect to its longitudinal
direction in its plan view while the lower layer is formed to have
a rectangular shape in its plan view, and the upper and lower
layers are laid such that a center line of the upper layer with
respect to its widthwise direction and that of the lower layer
correspond with each other.
4. Disposable underpants according to claim 2, wherein the first
nonwoven fabric of the intermediate layer of the adhesive unapplied
portion, and the adhesive applied portion forms an aggregate of a
multitude of lines.
5. Disposable underpants according to claim 2, wherein the outer
sheet includes an outermost nonwoven fabric and an inner nonwoven
fabric, and at least the leg elastic members and the fitting
elastic member are provided between these two nonwoven fabrics.
6. Disposable underpants according to claim 5, wherein the waist
elastic member is provided between a turned portion formed by
turning the outermost nonwoven fabric onto the inner nonwoven
fabric at the waist-opening edge and the inner nonwoven fabric.
7. Disposable underpants according to claim 1, wherein the fitting
elastic member is provided more toward the waistopening edge than a
longitudinal end of the absorbent core of the inner absorbent
member, so that the fitting elastic member and the absorbent core
do not overlap.
8. Disposable underpants according to claim 1, wherein the fitting
elastic member partly overlaps the absorbent .core of the inner
absorbent member, a portion thereof located in the overlapping
portion being provided in non-stretched state so as not to
contract.
9. Disposable underpants according to claim 1, wherein the
stretching force of the fitting elastic member differs in the front
and rear parts of the disposable underpants.
10. Disposable underpants according to claim 1, wherein each leg
elastic member is made of a plurality of thread-like elastic
materials, that thread-like elastic materials are, at the front
part of the disposal underpants, comprised of left and right side
portions extending along the leg-opening edges of the front part of
disposable underpants and connecting portions connecting the
leading ends of the side portions, thereby forming substantially
U-shaped lines, while being, at the rear part of the disposable
underpants, likewise comprised of left and right side portions
extending along the leg-opening edges of rear part of the
disposable underpants and connecting portions connecting the
leading ends of the side portions, thereby forming substantially
u-shaped lines, and the connecting portions of the front and rear
lines do not intersect with each other at the crotch of the
disposable underpants.
11. Disposable underpants according to claim 10, wherein the
spacing between the respective thread-like elastic materials of
each leg elastic member is narrowest at intermediate positions
between the side ends of the side portions and the middle of the
connecting portions and gradually widens toward the side ends of
the side portions and toward the middle of the connecting
portions.
12. Disposable underpants according to claim 10, wherein the
stretching force of the thread-like elastic materials of the leg
elastic members are weakest at intermediate positions between the
side ends of the side portions and the middle of the connecting
portions and gradually becomes stronger toward the side ends of the
side portions and toward the middle of the connecting portions.
13. Disposable underpants according to claim 1, wherein the left
and right side ends of the impermeable back sheet of the inner
absorbent member are turned up onto the upper surface of the
permeable top sheet, and raised gathers made of a nonwoven fabric
and provided with a stretchable member are adhered onto the upper
surfaces of the turned portions.
14. Disposable underpants according to claim 1, wherein the left
and right sides of the disposable underpants are bonded by putting
the outer sheet together and applying heating to melt it.
15. A method for continuously producing disposable underpants
according to claim 1, comprises the steps of: adhering a waist
elastic member, leg elastic members and a fitting elastic members
to a continuous web of an outer sheet, producing an absorbent core
by adhering an upper layer made of a mixture of pulp fibers and
super absorbent polymer particles and an lower layer made of a
mixture of pulp fibers and super absorbent polymer particles to the
upper and lower surfaces of first nonwoven fabric of an
intermediate layer by an adhesive, producing inner absorbent
members using the absorbent core, forming a laminated assembly by
adhering the inner absorbent members at specified intervals onto
the continuous web of the outer sheet having the respective elastic
members adhered thereto, folding the laminated assembly in two with
the inner absorbent members faced inward, providing cut-away
portions for the leg-openings in the laminated assembly folded in
two, bonding the opposite sides on the laminated assembly folded in
two, and separating the laminated assembly having its opposite
sides adhered at specified intervals to form the individual
disposable underpants.
16. A method according to claim 15, wherein disposable underpants
having different sizes are produced in the same production line by
adjusting the bonding intervals on continuous laminated assembly
folded or intervals at which the opposite sides of the disposable
underpants are bonded.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to disposable underpants
having such a shape that a waist-opening and a pair of leg-openings
are provided and left and right sides are bonded in advance, and
including an absorbent core which has an excellent shape retention
and is easily producible, and a method for continuously producing
such disposable underpants.
[0002] Since disposable underpants commercially available at
present are produced under a condition that a user walks and makes
physical motions while wearing them, an absorbent core is required
to have a high shape retention.
[0003] Accordingly, in the prior art, a thermoplastic resin in the
form of fibers and particles is mixed as a shape retaining material
in addition to pulp fibers and super absorbent polymer. particles.
More specifically, if such an absorbent core is heated, this
thermoplastic material is melted to adhere to the pulp fibers and
the super absorbent particles. Thus, the pulp fibers are adhered to
each other or adhered to the super absorbent polymer particles
after a heating treatment, thereby improving the shape retention of
the absorbent core. Further, the soft and bulky absorbent core can
be effectively maintained thin by the mixing of the thermoplastic
resin and the heating adhesion treatment.
[0004] However, if the thermoplastic resin fibers, particles, etc.
are not uniformly dispersed, i.e. concentrate in several locations
without being uniformly dispersed in the absorbent core, this
causes such a problem that portions of the absorbent core where the
thermoplastic resin is concentrated hinder the dispersion and
permeation of urine and/or prevent the super absorbent polymer
particles from swelling upon absorbing water, thereby reducing an
absorbing speed of liquid bodily wastes.
[0005] In order to produce the above absorbent core, an oven for
heating an absorbent core obtained by laminating fibers needs to be
prepared. A circulating hot blast oven is generally used as such an
oven, However, it is difficult for the hot blast to reach the
inside of the absorbent core obtained by laminating fibers to a
thickness of about 10 mm, and the absorbent core has to be passed
through the oven over an extended time in order to heat it until
the inside thereof reaches a melting temperature of the
thermoplastic resin. In order to extend the passing time in the
oven, the oven itself may be enlarged. However, this results in a
large-scale facility and is disadvantageous in terms of production
cost. As a result, the passing speed of the absorbent core in the
oven has to be slowed, which stands as a hindrance to an
improvement in production efficiency.
[0006] On the other hand, the conventional disposable underpants
are made of nonwoven fabric and others, also elastic members in the
form of threads or strips (made of natural rubber, polyurethane,
polyolefin elastomer, etc.) are provided near and around the
waist-opening and the pair of leg-openings. Even if stretchable
gathers are formed only around these openings , the disposable
underpants cannot be worn while ensuring a sufficient sealability.
Particularly, the disposable underpants provided with a bulky
absorbent core does not fit a user at the lower abdomen and the
buttocks and bulges out there. For example, if a person having a
light problem of incontinence wears a usual garment (trousers or
skirt) over disposable underpants, the disposable underpants cause
his or her waist line to bulge out, which is not a preferable
appearance. In view of the user's psychology, it is naturally
demanded to improve the disposable underpants to have such a shape
with which nobody would notice that the user is wearing them.
However, if a small absorbent pad is used so that nobody would
notice, a urine leak may occur. Even if no urine leak actually
occurs, users have refrained from going out due to an anxiety that
they might have a urine leak.
[0007] A first object of the present invention is to produce
disposable underpants provided with an absorbent member which is so
constructed as to have a good shape retention without mixing
thermoplastic resin fibers and particles into pulp fibers and
heating them. A second object of the present invention is to
provide disposable underpants which fit a user sufficiently and is
unlikely to let other people notice that the user is wearing
them.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to disposable underpants
having one waist-opening and a pair of leg-opening, having elastic
members provided near the edges of the waist-and leg-openings and
having the opposite sides thereof banded, comprising an outer sheet
and an inner absorbent member, wherein:
[0009] the outer sheet is provided with a waist elastic member, leg
elastic members and a fitting elastic member provided between
the,waist-elastic member and the leg elastic members, the fitting
elastic member being comprised of a plurality of thread-like
elastic materials in parallel with the waist elastic member,
[0010] the inner absorbent member includes a permeable top sheet,
an impermeable back sheet and an absorbent core accommodated
between the top and back sheets, and
[0011] the absorbent core includes an upper layer made of a mixture
of pulp fibers and super absorbent polymer particles, an
intermediate layer provided with a first nonwoven fabric, and a
lower layer made of a mixture of pulp fibers and super absorbent
polymer particles, the intermediate layers being adhered to the
upper and lower layers by an adhesive.
[0012] Further, a method for continuously producing disposable
underpants comprises the steps of:
[0013] adhering waist elastic members, leg elastic members and
fitting elastic members to a continuous web of an outer sheet,
[0014] producing absorbent cores by adhering upper layers made of a
Mixture of pulp fibers and super absorbent polymer particles and
lower layers made of a mixture of pulp fibers and super absorbent
polymer particles to the upper and lower surfaces of first nonwoven
fabric of intermediate layers by an adhesive,
[0015] producing inner absorbent members using the absorbent
cores,
[0016] forming a laminated assembly by adhering the inner absorbent
members at specified intervals onto the continuous web of the outer
sheet having the respective elastic members adhered thereto,
[0017] folding the laminated assembly in two with the inner
absorbent members faced inward,
[0018] providing cut-away portions for the leg-openings in the
laminated assembly folded in two,
[0019] bonding the opposite sides of the laminated assembly folded
in two, and
[0020] separating the laminated assembly having its opposite sides
adhered at specified intervals to form the individual disposable
underpants.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a front view of disposable underpants according to
the invention,
[0022] FIG. 2 is a developed plan view partly in section of the
disposable underpants of FIG. 1, FIG. 3 is a section showing an
embodiment of an inner absorbent member,
[0023] FIGS. 4(a) to 4(c) are plan views showing applied states of
adhesive,
[0024] FIG. 5 is a plan view of an absorbent core,
[0025] FIG. 6 is a section of the disposable underpants along their
longitudinal direction,
[0026] FIG. 7 is a front view showing another embodiment of the
invention,
[0027] FIG. 8 is a plan view showing how leg elastic members are
provided,
[0028] FIG. 9 is a perspective view showing a production method
according to the invention, and
[0029] FIG. 10 is a plan view showing the production method
according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE
INVENTION
[0030] One embodiment of disposable underpants according to the
invention is described in detail with reference to FIGS. 1 to 8.
Disposable underpants 1 are shaped by an outer sheet 2 to have a
waist-opening 3 at the top and a pair of leg-openings 4,4 as shown
in FIG. 1. Front and rear parts of the disposable underpants 1 are
bonded by left and right joint portions 5. In vicinity of the
waist-opening 3 and the leg-openings 4,4, a plurality of
thread-shaped elastic members (polyurethane, polyolefin elastomer,
rubber, etc.) are provided as a waist elastic members 53 and leg
elastic members 54. These elastic members 53, 54 form waist
stretchable gathers and leg stretchable gathers. Between the waist
elastic member 53 and the leg elastic members 54, a plurality of
thread-like elastic materials are provided as a fitting elastic
member 55 in parallel to the waist elastic members 53 over the
entire circumference of the disposable underpants 1. By the
presence of the fitting elastic member 55, the disposable
underpants 1 can fit the lower abdomen and buttocks of the user
with an improved sealability.
[0031] Inside the disposable underpants 1 is mounted an inner
absorbent member 6. An absorbent core 7 is contained inside the
inner absorbent member 6 for absorbing bodily wastes of the user
such as urine and loose stool. The positions of the fitting elastic
member 55 and the absorbent core 7 are preferably adjusted so that
a bottom end 55e of the fitting elastic member 55 is located more
toward a waist-opening end 3e than a longitudinal end 7e of the
absorbent care 7. If the fitting elastic member 55 and the
absorbent core 7 overlap, the stretching force of the fitting
elastic member 55 may be hindered since the absorbent core 7 is
relatively hard. Further, by limiting the position of the bulky
absorbent core 7 to the one below the crotch which is necessary to
absorb bodily wastes, the thickness of the disposable underpants I
at the lower abdomen and the buttocks which tend to bulge out after
the disposable underpants 1 are worn can be reduced. As a result,
the disposable underpants 1 can be made unnoticeable.
[0032] FIG. 2 is a development of the disposable underpants 1 of
FIG. 1. The disposable underpants 1 are substantially comprised of
the outer sheet 2 and the inner absorbent member 6. The inner
absorbent member 6 is bonded in the middle of the outer sheet 2,
and joint margins 5a, 5a at the opposite sides of a section B of
the outer sheet 2 corresponding to the rear side of the disposable
underpants 1 and joint margins 5b, 5b at the opposite sides of a
section F of the outer sheet 2 corresponding to the front side of
the disposable underpants 1 are put together and joined, thereby
obtaining the disposable underpants 1 having a shape as shown in
FIG. 1. The outer sheet 2 is comprised of an outermost nonwoven
fabric 21 and an inner nonwoven fabric 22. In an example of FIG. 2,
the outermost nonwoven fabric 21 of the outer sheet 2 extends
longer than the inner nonwoven fabric 22 at the waist-opening end
3e, and this projecting portion is turned down onto the inner
nonwoven fabric 21, thereby forming a turned portion 21a. The waist
elastic member 53 in its stretched state is intermittently adhered
between the turned portion 21a and the inner nonwoven fabric 22.
The fitting elastic member 55 and the leg elastic members 54 are
provided between the outmost nonwoven fabric 21 and the inner
nonwoven fabric 22. It should be noted that the waist elastic
member 53 may be provided between the outermost nonwoven fabric 21
and the inner nonwoven fabric 22. In such a case, the turned
portion 21a may or may not be provided.
[0033] Nonwoven fabrics made of cellulose, rayon, acetate,
polyethylene, polypropylene, nylon, polyester, acrylic fiber, etc.
(hereinafter, nonwoven fabrics are referred to as these nonwoven
fabrics) can be preferably used for the outermost nonwoven fabric
21 and the inner nonwoven fabric 22 and others. Nonwoven fabrics to
which a water repellent treatment is applied may be used. A
hot-melt adhesive can be conveniently used to adhere the respective
elastic members to the respective nonwoven fabrics.
[0034] The inner absorbent member 6 is comprised of an impermeable
back sheet 61 located at the outermost in this member 6, the
absorbent core 7 and a permeable top sheet 62 to fit a user's skin.
The impermeable back sheet 61 may be caused to project at the left
and right sides of the absorbent core 7, and the projecting
portions may be turned onto the upper surface of the top sheet 62
as indicated by a hatched portion 61a in FIG. 2. This prevents
urine from leaking through the opposite sides of the absorbent core
7.
[0035] FIG. 3 is a section showing a preferable embodiment of the
inner absorbent member 6 along its widthwise direction. The
absorbent core 7 in the inner absorbent member 6 essentially
consists of an upper layer 71, a lower layer 72 and an intermediate
layer 73 including a first nonwoven fabric. The upper and lower
layers 71, 72 are made of a mixture of pulp fibers and super
absorbent polymer particles. The content of the super absorbent
polymer particles is preferably about 10 to 65% by weight of the
entire weight of the absorbing material (a total of the upper and
lower layers) in order to rapidly absorb bodily wastes.
[0036] In the example of FIG. 3, a second nonwoven fabric 75 is
provided below the lower layer 72 and above the impermeable back
sheet 61, and a tissue 74 is provided above the upper layer 71 and
below the top sheet 62. The tissue 74 and the upper layer 71; the
upper layer 71 and the first nonwoven fabric 73; the first nonwoven
fabric 73 and the lower layer 72; and the lower layer 72 and the
second nonwoven fabric 75 are bonded to each other by a hot-melt
adhesive or the like, respectively, thereby forming the absorbent
core 7 as a whole.
[0037] The upper layer 71 and the first nonwoven fabric 73, and the
first nonwoven fabric 73 and the lower layer 72 are bonded by
applying the hot-melt adhesive to the first nonwoven fabric 73. It
is preferable to bond them before the hot-melt adhesive solidifies.
This is because the upper and lower layers 71 and 72 are bonded by
the hot-melt adhesive permeated along the thickness direction of
the first nonwoven fabric 73. Since the upper and lower layers
71,72 are firmly bonded to each other via the first nonwoven fabric
73 in the inventive absorbent core 7, the first nonwoven fabric
acts as a core member, thereby giving the absorbent core 7 an
excellent shape retention. Further 7 since the hot-melt adhesive
permeates through the upper or lower layer to bond the pulp fibers
to each other and the pulp fibers and the super absorbent polymer
particles, this is also effective in improving the shape retention.
Accordingly, if the inventive absorbent core constructed as above
is used, it is not necessary to mix thermoplastic resin fibers into
the absorbent core and to heat the absorbent core.
[0038] Further, by turning the side portions of the second nonwoven
fabric 75 projecting from the lower layer 72 onto the lower layer
72 or by bending the tissue 74 at the opposite sides of the upper
layer 71 and bonding the bent portions, the shape retention of the
absorbent core 7 can be further improved. Since the tissue 74 and
the second nonwoven fabric 75 can be used as a material for
wrapping the upper and lower layers in a production line for the
upper and lower layers 71, 72, they are useful in preventing the
pulp fibers and the super absorbent polymer particles from being
dispersed into a working environment in the production line.
[0039] When the upper layer 71, the lower layer 72, the first
nonwoven fabric 73 as an intermediate layer, the tissue 74, and the
second nonwoven fabric 75 are bonded by the hot-melt adhesive, it
is necessary to provide unapplied portions of the hot-melt adhesive
so as not to hinder the absorption of bodily wastes such as urine
and loose stool by the absorbent core 7. Particularly, unless the
unapplied portions are provided in the first nonwoven fabric 73, it
is not preferable since the bodily wastes do not permeates through
the lower layer 72. In order to provide the unapplied portions, the
hot-melt adhesive may be applied such that the applied portions
form an aggregate of lines such as spirals, a net or irregular
lines as shown in FIGS. 4(a), 4(b) and 4(c). It is easy to apply
the melted hot-melt adhesive in such a manner as to form an
aggregate of lines by applying it by the nozzle coating method,
spray coating method, or the like. It should be noted that the
hot-melt adhesive may he applied in strips or dots.
[0040] The upper layer 71 of the absorbent core 7 is narrowed at
the left and right sides in the middle with respect to its
longitudinal direction to form narrow parts 47,47 so that it has a
substantially sandglass-like shape as shown in FIG. 5. These narrow
parts 47, 47 are adapted so as not to hinder the stretchability of
the leg elastic members 54,54 (see FIG. 1) of the leg-openings
(identified by 4 in FIG. 1). Although the lower layer 72 may have
the same shape as the upper layer 71, it preferably has a
rectangular shape whose width is slightly smaller than that of the
upper layer 71. Since the bodily wastes are mostly absorbed by the
upper layer 71, the lower layer 72 may be provided as an auxiliary
absorbing member in the case that a large amount of urine needs to
be absorbed. Thus, the lower layer 72 can be made smaller than the
upper layer 71. The smaller lower layer 72 reduces the bulging-out
of the disposable underpants at the crotch, which makes the
disposable underpants unnoticeable in appearance after being worn
and prevents the stretchability of the leg gathers from being
hindered. Since the human legs are normally thicker at the thighs
near the crotch than at the crotch, the absorbent core is less
likely to be worn or twisted due to the user's movements (rubbing
of the thighs against each other) to have an improved shape
retention if the lower layer 72 is made smaller.
[0041] The absorbent core 7 constructed as above is suitably bonded
between the impermeable back sheet 61 and the permeable top sheet
62 as shown in FIG. 3. Of course, the top sheet 62 and the tissue
74 (the upper layer 71 when no tissue is provided) are so bonded as
not to hinder the water permeability. The bottom end of raised
gathers 81 may be bonded to the upper surface of the turned portion
61a which is a portion of the back sheet 61 turned onto the upper
surface of the top sheet 62. By providing thread-shaped elastic
members 82 at the leading ends of the raised gathers 81, the raised
gathers 81 rise against the user's skin, with the result that the
flow of the urine can be effectively stopped.
[0042] FIG. 6 is a section of the disposable underpants along the
longitudinal direction showing a preferable embodiment near the
waist-opening. The outermost nonwoven fabric 21 is turned toward
the inner nonwoven fabric 22 at the waistopening edge, thereby
forming the turned portion 21a as also shown in FIG. 2. The waist
elastic member 53 is provided between the turned portion 21a and
the inner nonwoven fabric 22. The fitting elastic member 55 is
provided between the outermost nonwoven fabric 21 and the inner
nonwoven fabric 22 such that its bottom end 55e is located more
toward the waist-opening end (upper side in FIG. 6) than the
longitudinal end 7e of the absorbent core 7 in the inner absorbent
member 6. In the example of FIG. 6, a separate nonwoven fabric 23
is provided from below the turned portion 21a to the upper end of
the inner absorbent member 6. This nonwoven fabric 23 is provided
if necessary. If the nonwoven fabric 23 made of water repellent
fibers is used or a water repellent treatment is applied to make
the nonwoven fabric water impermeable, the penetration of the urine
into portions of the disposable underpants outside the inner
absorbent member 6 can be prevented.
[0043] In all of the above examples, the positions of the fitting
elastic member 55 and the absorbent core 7 in the absorbent member
6 are adjusted such that the bottom end 55e of the fitting elastic
member 55 is located more toward the waist-opening end than the
longitudinal end 7e of the absorbent core 7, i.e. the fitting
elastic member 55 and the absorbent core 7 do not overlap. However,
the fitting elastic member 55 and the absorbent core 7 may
overlap.
[0044] For example, FIG. 7 shows an example of disposable
underpants in which the inner absorbent member 6 and the absorbent
core 7 are longer than those of FIG. 1. The same elements as those
shown in FIG. 1 are not shown in FIG. 7 There is an overlapping
area (hatched area X) of the fitting elastic member 55 (thread-like
fitting elastic materials in the order of ten are provided between
the upper end 55ue and the bottom end 55e, but are not shown in
FIG. 7) and the absorbent core 7. Since the absorbent core 7 is
harder than the nonwoven fabric, the action of the stretchability
of the fitting elastic materials on the area X does not improve the
sealability of the disposable underpants, but may causes the
absorbent core 7 to be worn out. However, it is complicated to cut
only the fitting elastic materials overlapping with the absorbent
core 7 during the production. Therefore, it is preferable to bond
the fitting elastic member 55 to the outer sheet 2 without being
stretched in the area X. By adopting this method, the fitting
elastic member 55 can be continuously provided without being cut in
the production line and there is no bad influence on the absorbent
core 7 when the disposable underpants are worn.
[0045] Independent of whether the fitting elastic member be changed
between the front and rear sides of the disposable underpants. In
the case of large-size disposable underpants frequently used by
people having large buttocks, sealability can be ensured even if
the stretching force of the rear side is made weaker than that of
the front side, so that the buttocks are not forcibly tightened.
Further, since most of the lean people have small buttocks, it is
preferable to substantially equally set the stretching forces of
the front and rear sides in small-size disposable underpants.
Furthermore, the fitting elastic member may be provided in
different positions(upper and lower portions) at the front and rear
sides of the disposable underpants.
[0046] FIG. 8 is a diagram showing how the leg elastic members 54,
54 according to the invention are provided. In the front part F of
the disposable underpants, the leg elastic member 54 is comprised
of left and right side portions 54a, 54c extending along the edges
of the leg-openings 4, 4, and a connecting portion 54b connecting
the leading ends of the side portions 54a, 54c, and forms a
substantially U-shaped line. The same applies to the rear part B of
the disposable underpants. As shown in FIG. 8, the connecting
portions 54b of the front and rear lines of the leg elastic members
54 do not intersect with each other at the crotch of the disposable
underpants. If they intersect at the crotch, the inner absorbent
member 6 is squeezed outward of the disposable underpants by the
stretching forces of the leg elastic members 54, 54, resulting in a
poor appearance. The positions of the front and rear U-shaped lines
of the connecting portions 54b where they are opposed to each other
may be displaced to either the front or rear part of the disposable
underpants.
[0047] The spacing between the respective thread-like elastic
materials forming the leg elastic members 54 is narrowest in
intermediate portions (S.sub.2) between the side ends of the side
portions 54a (or 54c) and the middle portion of the connecting
portions 54b and gradually widens toward the side ends (S.sub.1) of
the side portions and toward the middle portion (S.sub.3) of the
connecting portions 54b. Further, the thread-like elastic materials
are preferably provided such that their stretching forces are
weakest in the intermediate portions between the side ends of the
side portions 54a (or 54c) and the middle portion of the connecting
portions 54b and gradually become stronger toward the side ends
(S.sub.1) of the side portions and toward the middle portion
(S.sub.3) of the connecting portions 54b. By this construction, the
crotch of the disposable underpants can closely fit the user and
does not give any pain to the user by pressing his/or groin.
[0048] The disposable underpants according to the invention are
formed into the shape as shown in FIG. 1 by bonding the joint
margins 5a, 5b at the opposite sides of the front and rear parts in
the development of FIG. 2. At this time, the joint construction at
the opposite sides of the disposable underpants is such that the
outer sheet 2 in which be laminated three sheets: the outermost
nonwoven fabric 21, the inner nonwoven fabric 22 and the turned
portion 21a, are laid one over another are put together in a
portion where the turned portion 21a of the outermost nonwoven
fabric 21 is present, whereas the outer sheets 2 comprised of two
sheets: the outermost nonwoven fabric 21 and the inner nonwoven
fabric 22, are put together in a portion where the turned portion
21a is absent (i.e. the crotch side).
[0049] Further, in the disposable underpants constructed as shown
in FIG. 6, since the nonwoven fabric 23 is laid in addition to the
turned portion 21a in some portion of the outer sheet, the outer
sheet comprised of these is bonded. The joint margins at the
opposite sides of the disposable underpants can be easily bonded
using a heat sealer or an ultrasonic welding machine. If the
bonding force is insufficient, an other thermoplastic film,
nonwoven fabric, adhesive net, adhesive or the like may be added
between any arbitrary layers to improve the bonding force.
[0050] As is clear from FIG. 1, most of the inventive disposable
underpants is formed only by the outer sheet made of nonwoven
fabrics, and the impermeable sheet (as 61 in FIG.1) which causes
sweatiness is present only where the inner absorbent member is
provided. Therefore, the inventive disposable underpants have an
excellent breathability.
[0051] Hereinafter, a method for producing the inventive disposable
underpants is described with reference to FIGS. 9 and 10. According
to the inventive method, the waist elastic member, the leg elastic
members and the fitting elastic member are first provided on the
continuous web of the outer sheet. In FIG. 9, continuous elastic
strands 153, 154 and 155 of the waist elastic member (53) the leg
elastic members (54, 54) and the fitting elastic member (55) are
applied to a continuous web 121 of the outer-nonwoven fabric (21).
In this step, a hot-melt adhesive is sprayed onto the continues web
121 of the outermost nonwoven fabric (21) and/or the continuous
elastic strands 153 to 155 of the respective elastic members (53 to
55), the continues elastic strands 153 to 155 are adhered to
specified positions of the continues web 121 while being stretched,
a continuous web 122 of the inner nonwoven fabric (22) is placed on
the continuous web 121 having the continuous elastic strands 153 to
155 adhered thereto, and these continuous members 121, 153 to 155,
and 122 are pressed by rollers 10, 10 to adhere to each other. In
order to provide the leg elastic members (54, 54) in U-shaped line
as shown in FIG. 8, support guides (not shown in FIG.6 for the
continuous elastic strands 154 are vertically moved in a direction
normal to a running direction while the continuous web 121 is
running, so that the continuous elastic strands 154 are adhered in
a continuous sinusoidal curve. When the individual
disposable-underpants are separated, the leg elastic members 54, 54
form U-shaped lines. By this step, a continuous web 12 of the outer
sheet (2) in which the respective elastic members are provided is
formed.
[0052] It should be noted that a step of providing the turned
portions 21a of the outermost nonwoven fabric 21 and a step of
providing the another nonwoven fabric 23 can be added.
[0053] Subsequently, the inner absorbent members 6 produced in a
separate step are adhered to the outer sheet continuous web 12.
These inner absorbent members 6 are produced by a step of producing
the absorbent core by adhering the upper and lower layers made of a
mixture of the pulp fibers and the super absorbent polymer
particles to the upper and lower surfaces of the first nonwoven
fabric as the intermediate layer, a step of placing the top sheet
on the absorbent core after the absorbent core is placed on the
back sheet and rolling up the opposite sides of back sheet in such
a manner as to wrap the absorbent core and adhering them to the top
sheet, and, if desired, a step of adhering the members of the
raised gathers. Of course, a step of adhering the tissues (74) and
the second nonwoven fabric (75) shown in FIG. 3 can be added in the
step of producing the absorbent core.
[0054] After the inner absorbent members 6 are adhered to the outer
sheet continuous web 12 at specified intervals, a step of folding
the continuous web 12 in two with the inner absorbent members 6
faced inward, a step of bonding the opposite sides of disposable
underpants P.sub.1, P.sub.1 along bonding lines AL,AL a step of
cutting along cutting lines CL.sub.2 to provide cut-away portions
for the leg-openings, and a step of cutting along cutting lines
CL.sub.1 to separate the individual disposable underpants P.sub.1,
P.sub.2 are successively performed. It does not matter which of the
second and the third ones of the above four steps are performed
prior to the other. Alternatively, the third step may be provided
before the first step.
[0055] Since the absorbent cores need not be heated according to
the inventive production method, the inner absorbent members can be
manufactured at a high speed. Further, the disposable underpants
can be continuously manufactured at a high speed since the
respective elastic members are applied in the same direction as the
running direction of the continuous web of outer sheet and the
folding step and the bonding step do not hinder the running of the
continues web of outer sheet.
[0056] Further, according to the inventive production method, it is
not necessary to prepare a producing apparatus for each size. For
example, if disposable underpants P.sub.1 having a large waist size
W.sub.1 and disposable underpants P.sub.2 having a small waist size
W.sub.2 are produced in the same production line as shown in FIG.
10, it is sufficient to change the positions of the cutting lines
CL.sub.1,CL.sub.3 and the bonding lines AL in FIG. 9. More
specifically, as seen from FIGS. 9 and 10, a waist-opening length
(2.times.W.sub.1) of the disposable underpants P.sub.1 is
determined by the cutting lines CL.sub.1 indicated by phantom line
and the bonding lines AL (solid line) provided inside the cutting
lines CL.sub.1, CL.sub.1. Further, the leg-opening length is
2.times.L.sub.1. The disposable underpants P.sub.2 having a smaller
waist width W.sub.2 than W.sub.1 can be easily produced by using
the cutting lines CL.sub.3,CL.sub.3 (indicated by dotted line)
instead of the cutting lines CL.sub.1, CL.sub.1, and defining the
bonding lines AL.sub.2, AL.sub.2 inside the cutting lines CL.sub.3,
CL.sub.3. Since the leg-opening length (2.times.L.sub.2) of the
disposable underpants P.sub.2 are smaller than that of the
disposable underpants P.sub.1, there can be provided disposable
underpants adapted to the actual situation where people having a
slender waist generally have slender legs.
* * * * *