U.S. patent application number 10/920459 was filed with the patent office on 2005-04-14 for disposable absorbent article and process for making the same.
This patent application is currently assigned to UNI-CHARM CORPORATION. Invention is credited to Otsubo, Toshifumi, Sugito, Tomoko, Yamamoto, Hiroki.
Application Number | 20050080394 10/920459 |
Document ID | / |
Family ID | 34197128 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050080394 |
Kind Code |
A1 |
Otsubo, Toshifumi ; et
al. |
April 14, 2005 |
Disposable absorbent article and process for making the same
Abstract
A disposable absorbent article such as a disposable diaper
including fastener means by means of which front and rear waist
regions are releasably connected with each other improved so that
the fastener means are not affected by contraction of elastic
members arranged in these waist regions In this absorbent article,
a waist region and/or a waist region is or are divided into
elasticized intermediate zone provided with elastic means and
inelasticized transversely opposite side edge zones provided with
none of the elastic means and contiguous to transversely opposite
side edges of the intermediate zone. Fastener means are provided in
the transversely opposite side edge zones.
Inventors: |
Otsubo, Toshifumi;
(Kagawa-ken, JP) ; Yamamoto, Hiroki; (Kagawa-ken,
JP) ; Sugito, Tomoko; (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: |
34197128 |
Appl. No.: |
10/920459 |
Filed: |
August 18, 2004 |
Current U.S.
Class: |
604/385.27 |
Current CPC
Class: |
A61F 13/565 20130101;
A61F 13/49011 20130101; A61F 13/5655 20130101; A61F 2013/49028
20130101 |
Class at
Publication: |
604/385.27 |
International
Class: |
A61F 013/15; A61F
013/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 2003 |
JP |
2003-207952 |
Jun 1, 2004 |
JP |
2004-163419 |
Claims
What is claimed is:
1. A disposable absorbent article comprising: an absorbent chassis
having a first waist region; a second waist region, a crotch region
extending between these waist regions; leg region extending on
transversely opposite sides of said crotch region wherein; of said
first and second waist regions, at least said first waist region
being provided with first elastic means adapted to operate in a
waist-surrounding direction of a wearer; said leg regions being
provided second elastic means adapted to operate in a
leg-surrounding direction of the wearer; said first waist region
being provided along transversely opposite side edge portions
thereof with fastener means adapted to be releasably engaged one
with another and thereby to releasably connect said first and
second waist regions; and said first waist region having an
elasticized intermediate zone and inelasticized transversely
opposite side edge zones in which said fastener means are attached
to said first waist region.
2. The article as set forth by claim 1, wherein said fastener means
are attached to said first waist region in said transversely
opposite side edge zones through the intermediary of reinforcing
layers made of material provided separately of said first waist
region.
3. The article as set forth by claim 1, wherein said chassis
comprises a flexible and liquid-resistant base sheet having inner
and outer surfaces and semirigid absorbent panel fixed to said
inner surface.
4. The article as set forth by claim 3, wherein said base sheet
comprises a laminate sheet consisting of at least two sheets
intermittently bonded together and said first and second elastic
means are interposed between said two sheets.
5. The article as set forth by claim 1, wherein said first elastic
means are provided substantially over a whole area of said
intermediate zone.
6. The article as set forth by claim 1, wherein said first and
second elastic means comprise a plurality of thread- or strand-like
means having rubber elasticity.
7. The article as set forth by claim 1, wherein said fastener means
comprise mechanical fasteners or fasteners formed by adhesive
directly or indirectly applied on said chassis in desired regions
thereof.
8. The article as set forth by claim 1, wherein said fastener means
are continuously or intermittently provided on said first waist
region over a range defined between end portions opposed in a
vertical direction of said chassis.
9. The article as set forth by claim 1, wherein said first and
second elastic means comprise a plurality of elastic members and
longitudinally opposite ends of said elastic members are laid in
the vicinity of side edges of said fastener means and oriented so
as to cross these side edges.
10. The article as set forth by claim 1, wherein said article is an
open type diaper or a pull-on type diaper.
11. A process for making the article as set forth by claim 1,
comprising the steps of feeding a plurality of continuous elastic
members extending in parallel to and spaced from one another, onto
a continuous web destined to form individual base sheets
constituting said chassis so as to be fixed to a first zone of said
web corresponding to said intermediate zone and treating said
elastic members lying in second zones of said web corresponding to
said transversely opposite side edge zones to be inelasticized.
12. The process for making the article as set forth by claim 11,
said step of inelasticizing said elastic members lying in said
second zones further includes a step of fixing said elastic members
lying in said second zones to said second zone and then cutting
said elastic members lying on a boundary line between said second
zones adjacent to each other along said boundary line so as to
leave said elastic members lying in said second zones contract.
13. The process for making the article as set forth by claim 11,
said step of inelasticizing said elastic members lying in said
second zones further includes a step of fixing said elastic members
lying in said second zones to said second zones and then cutting
said elastic members lying in said second zones in such fixed
state.
14. The process for making the article as set forth by claim 11,
said step of inelasticizing said elastic members lying in said
second zones includes a step of fixing said elastic members lying
in said second zones to said second zones and then forming said
second zones with a plurality of slits extending through said base
sheet in said second zones.
15. The process for making the article as set forth by claim 11,
said step of fixing said elastic members to said second zones is
achieved by means of adhesive intermittently applied on said web.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a disposable absorbent
article used for absorption and containment of body wastes and to a
method of making the same. The invention particularly relates to a
disposable absorbent article such as an open or pull-on type diaper
for an infant or incontinent patient or training pants and a method
of making the same. Regarding the method, the invention
particularly to a method comprising the step of attaching
waist-surrounding elastic members to a base sheet functioning to
support an absorbent panel and to hold this in close contact with a
wearer's body.
[0002] WO 01/13843 A1 (hereinafter referred to as "Citation 1")
relating to an absorbent article such as a disposable diaper
discloses a structure comprising a plurality of elastic members
provided in a rear waist region of the article and fastener means
detachably connecting the rear waist region with a front waist
region of the article wherein the fastener means are fixed to the
rear waist region so as to overlap the elastic members.
[0003] Japanese Patent No. 3096152 (hereinafter referred to as
"Citation 2") relating to a disposable diaper discloses a structure
comprising front and rear waist regions previously connected to
each other so that the diaper may be selectively used as an open or
pull-on type diaper, elastic members attached to front and rear
waist regions, respectively, a pair of fastener means attached to
transversely opposite side edge portions of the front waist region,
respectively, another fastener means attached to the rear waist
region so as to cooperate with those on the front waist region and
a pair of tear off lines provided along the transversely opposite
side edge portions of the front waist region, respectively, so
that, if desired, the front waist region can be torn off from the
rear waist region.
[0004] In the case of the absorbent article disclosed in Citation
1, the fastener means are fixed to the rear waist region so as to
overlap the elastic members, so the fastener means are formed with
gathers as the elastic members contracts. Such gathers make it
difficult to bring the fastener means in a firm engagement with a
landing zone and an unstable engagement is accompanied with a
problem that the fastener means may be unintentionally disengaged
from the landing zone.
[0005] As one of measures to overcome such a problem, it may be
contemplated that none of the elastic members is distributed over
the part of the waist region to be provided with the fastener
means. While it is technically possible to provide the waist region
partially with the elastic members, such a measure is not suitable
for a mechanical apparatus driven at a high speed to mass produce
the article as described herein at a low cost. For this reason, in
generally, the elastic members are provided along a full length of
a waist-surrounding circumference and the fastener means are
attached to the waist region so as to overlap these elastic
members.
[0006] In the case of the diaper disclosed in Citation 2, the front
waist region is provided along its transversely opposite side edge
portions with a pair of tear off lines, respectively, along which
the front waist region are torn off from the rear waist region.
Assumed that these waist regions are forced by a nonwoven fabric
made of staple fibers or continuous filaments of synthetic resin as
this is usually the case and particularly such a nonwoven fabric
contains fibers or filaments oriented to cross the tear off
direction defined by the tear off lines, it is difficult to tear
the front waist region off from the rear waist region.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide a
disposable absorbent article adapted to solve the problem as has
been described above and a method of making the same.
[0008] It is another object of the present invention to provide a
disposable absorbent article including a fastener means adapted to
be free from the affection of elastic members even when these
elastic members contract and a method of making the same.
[0009] It is still another object of the present invention to
provide a disposable absorbent article having front and rear waist
regions previously connected with each other and adapted to be
easily torn off from one another, if desired, and a method of
making the same.
[0010] Regarding the objects of the present invention as have been
described just above, it should be understood that the invention
set forth by each of Claims can achieve at least one of the
above-mentioned objects but not all of the above-mentioned
objects.
[0011] As used herein, the term "chassis" refers to a main body of
an absorbent article. Namely, the chassis is formed from a material
differing from the material for the main body in the conventional
disposable absorbent article and components such as tape-like tabs
attached to transversely opposite side edge portions of the main
body so as to extend outward from these side edge portions do not
correspond to the transversely opposite side edge portions of the
chassis according to the present invention. The fastener means do
not include a fastener means provided on such tabs.
[0012] As used herein, the term "elasticized" refers to a state
that elastic members have been provided in desired regions made of
a material having no rubber elasticity and thereby such regions
have been imparted with elastic contractility.
[0013] As used herein, the term "inelasticized" refers to a state
that the elastic members were provided in desired regions but
subsequent treatment has made these regions as if none of the
elastic members are present in these regions or refers to a state
that, even though the elastic member are present in those regions,
the elastic members in the relevant regions have been deprived of
contractility required for the article by subsequent treatment.
[0014] As used herein, the term "fastener means" refers to a means
having function substantially the same as those well known in the
name of Velcro (trademark) or Magic Tape (trademark). Specifically,
the term "fastener means" refers to the means comprising a hook
member consisting of a hook backing and a plurality of hook
elements extending upward from the hook backing and a loop member
consisting of a loop backing and a plurality of loop elements
projecting or standing out from the loop backing so that these hook
and loop members may be releasably engaged with each other. It
should be noted here that the material having a loop function such
as a fibrous nonwoven fabric constituting the article may be used
as the loop member. It is also possible to replace the hook member
and the loop member by an adhesive applied directly or indirectly
on the chassis as "fastener means".
[0015] As used herein, the term "first waist region" refers to one
of the front and rear waist regions of the article and the tern
"second waist region" refers to the other of the front and rear
waist regions.
[0016] One or more of the objects set forth above can be achieved,
according to the present invention, by an improvement in a
disposable absorbent article comprising: an absorbent chassis
having a first waist region; a second waist region; a crotch region
extending between these waist regions; leg region extending on
transversely opposite sides of the crotch region; of the first and
second waist regions, at least the first waist region being
provided with a first elastic means adapted to operate in a
waist-surrounding direction of a wearer; the leg regions being
provided with a second elastic means adapted to operate in a
leg-surrounding direction of the wearer; the first waist region
being provided along transversely opposite side edge portions
thereof with a fastener means adapted to releasably connect the
first to the second waist regions.
[0017] The improvement according to the present invention is in
that the first waist region has an elasticized intermediate zone
and inelasticized transversely opposite side edge zones in which
the fastener means are attached to the first waist region.
[0018] In the disposable absorbent article according to the present
invention, the first and/or second waist region(s) is or are
divided into the elasticized intermediate zone and inelasticized
transversely opposite side edge zones in which the fastener means
are provided. Such a unique arrangement is effective to protect the
fastener means from undulation due to contraction of the elastic
members laid to elasticize at least the waist regions and, in
consequence, proper engagement between the cooperating fastener
means is assured. In this way, there is no anxiety that the
fastener means might be affected or deteriorated by contraction of
the elastic members and unintentionally disengaged from each other
as has been described above in the paragraph regarding the prior
art.
[0019] Preferably, the fastener means are attached to the first
waist region in the transversely opposite side edge zones
preferably through the intermediary of reinforcing layers made of
material provided separately of the first waist region. The
reinforcing layers are effective to avoid undesirable deformation
and breakage of zones in the fastener means are located and to
stabilize mutual engagement of these fastener means.
[0020] Preferably, the chassis comprises a flexible and
liquid-resistant base sheet having inner and outer surfaces and a
semirigid absorbent panel fixed to the inner surface. Such an
arrangement is effective to enhance a good fit to the wearer s
body, to prevent body waste from leaking, to protect the wearer
from experiencing a feeling of discomfort due to stiffness of the
article and to prevent the chassis and the absorbent panel from
unintentionally moving relatively to each other.
[0021] Preferably, the base sheet comprises a laminate sheet
composed of at least two sheets intermittently bonded together and
the first and second elastic means are interposed between said two
sheets. Such an arrangement is effective to ensure a tensile and
tear strength required for the base sheet and to reliably fix the
elastic members to the base sheet.
[0022] Preferably, the first elastic means are provided
substantially over a whole area of the intermediate zone and the
first and second elastic means comprise a plurality of thread- or
strand-like means having rubber elasticity. Such an arrangement is
effective to hold the first and second waist regions around the
wearer's waist over a relatively wide range without giving the
wearer oppressive feeling.
[0023] Preferably, the fastener means comprise a mechanical
fasteners or adhesive fastener directly or indirectly applied on
the chassis in desired regions thereof and are continuously or
intermittently provided on the first waist region over a range
defined between end portions opposed in a vertical direction of the
chassis. Such an arrangement is effective, particularly when the
article has a structure by which the first and second waist regions
are detachably connected with each other, to ensure that a tensile
force with which the wearer's parent or care personnel pulls the
first and/or second waist region(s) with the transversely opposite
side edge portions thereof held in the hands can be transmitted to
a generally whole area of the waist region(s), to facilitate the
wearer s parent or care personnel to put the article on the
wearer's body, to assure a wide area of engagement and thereby to
improve a strength of engagement.
[0024] Preferably, the first and second elastic means comprise a
plurality of elastic members and longitudinally opposite ends of
the elastic members are laid in the vicinity of side edges of the
fastener means and oriented so as to cross these side edges. Such
an arrangement allows the first and second elastic members to be
operatively associated or to cooperate with each other.
Specifically, a contraction stress of the first elastic members are
operatively associated with a contraction stress of the second
elastic members. In other words, if the waist regions are
elastically pressed against the wearer's waist at an appropriate
pressure, the leg regions also will be elastically pressed against
the wearer, s legs at an appropriate pressure. Even when a pressure
at which the article is elastically pressed against the wearer's
body must be adjusted, it will be unnecessary to adjust the
pressure at which the waist regions should be pressed against the
wearer's waist and the pressure at which the leg region should be
pressed against the wearer's legs.
[0025] The article is an open type diaper or a pull-on type
diaper.
[0026] Preferably, a process for making the article comprises the
steps of feeding a plurality of continuous elastic members
extending in parallel to and spaced from one another, onto a
continuous web destined to form individual base sheets constituting
the chassis so as to be fixed to a first zone of the web
corresponding to the intermediate zone and treating the elastic
members lying in second zones of the web corresponding to the
transversely opposite side edge zones to be inelasticized Such an
arrangement facilitates the objects of the invention to be
achieved.
[0027] Preferably, the step of inelasticizing the elastic members
lying in the second zones further includes a step of fixing the
elastic members lying in the second zones to the second zone and
then cutting the elastic members lying on a boundary line between
the second zones adjacent to each other along the boundary line so
as to cause the elastic members lying in the second zones to snap
back. Such an arrangement is effective to prevent any trace of the
treatment from being left in the second zone.
[0028] Preferably, the step of inelasticizing the elastic members
lying in the second zones further includes a step of fixing the
elastic members lying in the second zones to the second zones and
then cutting the elastic members lying in the second zones in such
fixed state. Such an arrangement is effective to prevent any trace
of the treatment such as slits from being left in the second
zone.
[0029] Preferably, the step of inelasticizing the elastic members
lying in the second zones includes a step of fixing the elastic
members lying in the second zones to the second zones and then
forming the second zones with a plurality of slits extending
through the base sheet in the second zones. Such an arrangement
allows the slits along which the first and second waist regions to
be torn off from each other for conversion of the pull-on type
article to the open-type article to be simultaneously formed.
[0030] Preferably, the step of fixing the elastic members to the
second zones is achieved by means of adhesive intermittently
applied on the web. Such an arrangement effective to ensure
flexibility as well as breathability of the base sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a perspective view showing a disposable diaper
according to a first embodiment of the invention having front and
rear waist regions connected to each other;
[0032] FIG. 2 is a perspective view showing the diaper of FIG. 1
having the front and rear waist regions disconnected from each
other;
[0033] FIG. 3 is a sectional view showing the diaper of FIG. 1 as
taken along a transverse center line bisecting a longitudinal
dimension of the diaper;
[0034] FIG. 4 is a sectional view taken along the line IV-IV in
FIG. 2;
[0035] FIG. 5 is a perspective view showing a disposable diaper
according to a second embodiment of the invention having front and
rear waist regions disconnected from each other;
[0036] FIG. 6 is a plan view partially illustrating a process for
making the diapers according to the first and second embodiments of
the invention;
[0037] FIG. 7 is a perspective view showing a disposable diaper
according to a third embodiment of the invention having front and
rear waist regions connected to each other;
[0038] FIG. 8 is a perspective view showing the diaper of FIG. 7
having the front and rear waist regions partially disconnected from
each other; and
[0039] FIG. 9 is a sectional view taken along the line IX-IX in
FIG. 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] A disposable diaper illustrated in FIGS. 1 through 3 as a
specific embodiment of the disposable absorbent article according
to the invention has an absorbent chassis 10 comprising a front
waist region 12, a rear waist region 13, a crotch region 14
extending between these waist regions 12, 13, and a pair of leg
regions 14a defined by transversely opposite side edge portions of
the crotch region 14. The chassis 10 comprises a base sheet 17 and
an absorbent structure 18. The base sheet 17 has inner and outer
surfaces 15, 16 and exhibits a relatively high flexibility and
liquid-resistance and the absorbent structure 18 extends over the
crotch region 14 further into the front and rear waist regions 12,
13. The chassis 10 further comprises a plurality of elastic members
19 arranged in the front and rear waist regions 12, 13 as first
elastic members, a plurality of elastic members 20 provided in the
crotch region 14 along the respective leg regions 14a as second
elastic members, and fastener means 21, 22 attached to the outer
surface 15 of the base sheet along the transversely opposite side
edge portions of the front waist region 12 and attached to the
inner surface 15 of the base sheet 17 along the transversely
opposite side edge portions of the rear waist region 13,
respectively, so that the fastener means 21, 22 may be releasably
engaged with each other. In each of the front and rear waist
regions 12, 13, an elasticized intermediate zone 23 containing the
elastic members 19 arranged therein and inelasticized transversely
opposite side edge zones 24 containing none of the elastic members
19 arranged therein are respectively defined (See FIG. 4). In the
case of such diaper according to the invention basically arranged
in this manner, the front and rear waist regions may be connected
with each other by mutual engagement of the fastener means 21, 22
when the diaper is put on a wearer's body. While the invention has
been described above on the basis of the open type diaper as a
specific embodiment, the structural features of this embodiment are
applicable to a pull-on type diaper as will be described later as a
third embodiment of the invention.
[0041] The base sheet 17 is formed from a laminate composed of two
hydrophobic fibrous nonwoven fabric sheets 25, 26 intermittently
bonded together and curving inward in the crotch region 14 so as to
have its width reduced. Thus the base sheet 17 as a whole has an
hourglass-like planar shape. The nonwoven fabric sheets 25, 26 may
be treated with repellent conventionally used for component
materials constituting the article of the type as described herein
if it is desired to enhance a liquid-resistant effect. These
nonwoven fabric sheets 25, 26 may be selected from those obtained
by the methods of well known art for making various fibrous
nonwoven fabric sheets and the component fibers of these nonwoven
fabric sheets 25, 26 also may be selected from those conventionally
used as the component fibers for the article of this type.
[0042] The elastic members 19, 20 are fixedly interposed between
the nonwoven fabric sheets 25, 26 of the base sheet 17 and extend
in a transverse direction. Though not illustrated, fixation of the
elastic members 19, 20 is preferably achieved by hot melt adhesive
intermittently applied in a spiral pattern, dotted pattern, or
linear or curved stripe-pattern. Material for these elastic members
19, 20 may be natural or synthetic material so far as the material
has a rubber elasticity.
[0043] The elastic members 19 are arranged over almost whole area
defined between the vicinity of respective upper edges of the front
and rear waist regions 12, 13 and the vicinity of respective upper
edges of the crotch region 14 as viewed in FIGS. 1 and 2. The
elastic members 19a extending along an upper edge portion of a
waist-hole are spaced apart one from another by a relatively small
dimension and the elastic members 19b laid below the elastic
members 19a are spaced apart one from another by a relatively large
dimension. Alternatively, it is also possible to arrange both the
elastic members 19a and the elastic members 19b so as to be spaced
apart one from another by a uniform dimension, though no shown.
While a tensile stresses of these elastic members 19a, 19b may be
appropriately set zone by each of zones in which these elastic
members 19a, 19b are arranged, depending on a particular purpose
for which the article is used, these tensile stresses are set, in
general, so that the elastic members 19a arranged in the vicinity
of the waist-hole present a relatively high tensile stress and the
elastic members 19b arranged in the remaining zone present a
relatively low tensile stress. This is for the reason that the
elastic members 19a should function to hold the article on the
wearer's body while the elastic members 19b should function as an
auxiliary means to ensure a good fit of the article around the
wearer's body. To ensure such functions, these elastic members are
fixed preferably at least longitudinally opposite end portions
thereof to the base sheet 17. In this way, the base sheet 17 is not
formed with gathers as these elastic members contract and an
external appearance is protected from being disordered.
[0044] The elastic members 19, 20 respectively have longitudinally
opposite end portions 19c, 20a preferably laid in the vicinity of
the inner side edges of the respective fastener means 21, 22 and
oriented so as to cross these side edges. The elastic members 19,
20 arranged in this manner are operatively associated or cooperate
with each other through the intermediary of the fastener means 21,
22. Specifically, the contraction stress of the elastic members 19
is operatively associated with the contraction stress of the
elastic members 20. Thus if the front and rear waist regions 12, 13
are elastically pressed against the wearer's waist with an
appropriate fit, the leg regions of the diaper will be also
elastically pressed against the wearer's legs correspondingly with
an appropriate fit.
[0045] The fastener means 21, 22 function substantially in the same
manner as those of well known under the trademark "Velcro" or
"Magic Tape". One of the fastener means 21, 22 comprises a hook
member consisting of a hook-backing and a plurality of hooks
protruding from one surface of the hook backing and the other of
the fastener means 21, 22 adapted to be engaged with this hook
member comprises a loop member consisting of a loop backing and a
plurality of loops protruding or rising up out from one surface of
the look backing. These fastener means 21, 22 are made of material
having a stiffness higher than the base sheet 17. These fastener
means 21, 22 may be replaced by pressure-sensitive adhesive applied
directly or indirectly and continuously or intermittently on the
chassis 10. As used herein the term "applied indirectly on the
chassis" means that an appropriate backing is coated with adhesive
and this backing is bonded to the chassis 10 to form a fastener.
The fastener means comprising the loop member may be eliminated so
far as the fibrous nonwoven fabric or the reticular fabric
constituting the article can function as the loop member. The
fastener means 21, 22 may be fixed to the front and rear waist
regions 12, 13 along the transversely opposite side edge zones
thereof using hot melt adhesive and/or welding technique. Though
not illustrated, such fixation is preferably made through the
intermediary of a reinforcing layer 45 as will be described later
with respect to a third embodiment of the invention.
[0046] The pressure-sensitive adhesive may be selected from those
conventionally used in the technical field of this invention, for
example, natural rubber-based adhesive or synthetic rubber-based
adhesive such as acryl-based, silicone-based, or urethane-based
adhesive. It is also possible to use, as the pressure-sensitive
adhesive, natural latex mixed with one or more selected from the
group consisting of SBR emulsion, IR emulsion, acrylic polymer,
vinyl acetate, and ethylene/vinyl acetate copolymer in a given
proportion. A coating thickness of the adhesive is in a range of
approximately 5 to 100 .mu.m, preferably in a range of
approximately 10 to 60 .mu.m.
[0047] In view of desired advantageous effect as will be described,
the fastener means 21, 22 preferably have tape-like shapes and
continuously extend in a longitudinal direction of the chassis 10
over ranges substantially defined between longitudinally opposite
ends of the front and rear waist regions 12, 13, respectively.
Specifically, when the rear waist region 13 or the front waist
region 21 are stretched by the wearer's parent or care personnel
with the transversely opposite side edge portions of this waist
region held by the hands in order to put the article on the
wearer's body, a tensile force for such stretching can be exerted
on practically whole area of this waist region. Consequently, there
occurs no anxiety that this waist region might be evenly or
unevenly formed with gathers and prevented from coming in close and
neat contact with the wearer's body. In addition, an area of
engagement as wide as possible can be ensured and thereby an
engagement strength can be enhanced. Furthermore, the fastener
means 21, 22 have a stiffness sufficient to maintain the shapes of
the front and rear waist regions 12, 13. Therefore the fastener
means 21, 22 can be easily put in mutual engagement and
disengagement. Though not illustrated, an alternative arrangement
is also possible according to which the fastener means 21, 22
intermittently extend in the longitudinal direction of the article
or a plurality of the fastener means 21, 22 extend in parallel one
to another along each of the transversely opposite side edges so
far as the effect as has been described a just above is
achieved.
[0048] Depending on a particular size of the diaper, each of the
fastener means 21, 22 in the illustrated embodiment may have a
width dimension in a range of about 2 mm to about 30 mm and a
length dimension in a range of about 50 mm to about 200 mm,
preferably a width dimension in a range of about 5 mm to about 20
mm and a length dimension in a range of about 50 mm to about 150
mm. Such dimensioning is effective to assure a sufficient peeling
and shearing strength required for the fastener means 21, 22
particularly when these fastener means comprise the adhesive
applied directly or indirectly on the chassis 10.
[0049] As will be best seen in FIG. 3, the absorbent structure 18
comprises a liquid-absorbent core 28, a flexible and
liquid-pervious upper sheet 29 covering a top surface of the core
28-and a flexible and liquid-resistant lower sheet 30 covering a
bottom surface of the core 28. The upper and lower sheets 29, 30
respectively have portions 31, 32 extending outward beyond a
peripheral edge of the core 28 and bonded together. The absorbent
structure 18 is provided along its transversely opposite side edges
with a pair of flaps 33 having a relatively high flexibility,
contractility and liquid-resistance. Each of the flaps 33 has a
proximal edge portion 34 fixed between the base sheet 17 and the
portion 31, a distal edge portion 35 and longitudinally opposite
end portions 36 which are folded inward and bonded in such a folded
state to the upper sheet 29. Each of the flaps 33 further has an
elastic member 37 attached in a stretched state to the distal edge
portion 35 so that the elastic member 37 may function as an elastic
spacer means to space apart the flap 33 upward from the upper sheet
29 thereby forming a channel 38 adapted to receive body waste.
[0050] The core 28 comprises a mixture of fluff pulp and
water-insoluble polymer particles having an absorption capacity
corresponding to at least 20 times of its own weight, both
components being well known in the art and appropriately
compressed. Compared to the upper and lower sheets 29, 30 having a
high flexibility, the core 28 is relatively stiff, i.e., semirigid.
Though not illustrated, a general entirety of the core 28 is
preferably wrapped with a liquid-absorbent/diffusible sheet such as
tissue paper not only to achieve convenience for production of the
article but also to prevent the core 28 from getting out of its
initial shape and to prevent the polymer particles from falling
off.
[0051] The upper and lower sheets 29, 30 are formed from nonwoven
sheets. Such nonwoven sheets may be selected from those obtained by
various methods of well known art for making a fibrous nonwoven
fabric and conventionally used as the component material for the
article of the type described herein.
[0052] To simplify the description of a second embodiment, the
components and portions corresponding to those in the first
embodiment will be denoted by the same reference numeral as those
used to illustrate the first embodiment and the arrangements
similar to those in the first embodiment will be omitted wherever
possible.
[0053] FIG. 5 shows the second embodiment distringuished from the
first embodiment only with respect to the transversely opposite
side edge portions of the rear waist region 13. More specifically,
ear flaps 13A made of separately prepared material are connected to
the transversely opposite side edge portions of the rear waist
region 13 so as to form a part of the chassis 10 according to the
second embodiment while ear portions on the transversely opposite
side edge portions of the rear waist region 13 are integrally
formed by the chassis 10 according to the first embodiment. The ear
flaps 13A are formed from a sheet material such as a fibrous
nonwoven fabric having a tensile strength at least equal to the
tensile strength of the base sheet 17 and preferably having a
stiffness higher than the stiffness of the respective sheet
materials constituting the base sheet 17. The respective ear flaps
13A are connected to the chassis 10 along seaming lines 39 by
heat-sealing or sonic-sealing proximal edge portions of the
respective ear flaps 13A and the respective side edge portions of
the chassis 10 with each other. The ear flaps 13A are provided on
the inner surfaces thereof with the fastener means 22.
[0054] FIG. 6 schematically illustrates a method for attaching the
elastic members 19 to one of the front and rear waist regions 12,
13. Referring to FIG. 6, a continuous web 117 includes regions
corresponding to a series of the front waist regions 12 or the rear
waist regions 13 but remaining regions corresponding to a series of
the other waist regions, the absorbent structure 18 and the
leg-surrounding elastic members 20 are not illustrated.
[0055] According to this method, a plurality of continuous elastic
members 119 spaced apart one from another and extending in parallel
one with another, all being stretched at a given ratio are fed onto
the continuous web 117 destined to define the base sheets 17. First
zones 123 of the web 117 destined to define the intermediate zones
23 are coated with hot melt adhesive (not shown) while second zones
124 destined to define the transversely opposite side edge zones 24
are not coated with the adhesive. The elastic members 119 are
bonded to the first zones 123 by means of the adhesive coated
thereon. In the respective second zones 124, mechanical fasteners
are attached to the web 117 or pressure-sensitive adhesive is
directly or indirectly applied on the chassis 10 to form the
fasteners. Along a boundary line 150 between each pair of the
adjacent second zones 124, the web 117 is cut together with the
elastic members 119. Thereupon, as will be seen on the left side of
the diagram, each group of the elastic members 119 laid in the
respective second zones 124 automatically contract or snap
back.
[0056] For high speed mass production of the article, the step of
cutting is preferably carried out after the individual components
have assembled in the form of the continuous web comprising the
individual articles arranged side by side.
[0057] In this embodiment, to simplify the description, the
components and portions corresponding to those in the first
embodiment will be denoted by the same reference numeral as those
used to illustrate the first embodiment and the arrangements
similar to those in the first embodiment will be omitted wherever
possible.
[0058] As will be apparent from FIGS. 7 through 8, the front and
rear waist regions 12, 13 of the absorbent chassis 10 and the side
edge portions of the respective ear flaps 40 are overlapped and
connected together by seam lines 41 extending along these side edge
portions, whereupon a pull-on type diaper is formed with a
waist-hole 42 and a pair of leg-holes 43.
[0059] In the front waist region 12, the elastic members 19 extend
beyond the intermediate zone 23 to the transversely opposite side
edge zones 24 and these extensions of the elastic members 19 are
cut into small segments in the longitudinal direction thereof
through the base sheet 17 by a plurality of rows of slits 44 each
extending intermittently in the vertical direction of the article
and arranged in parallel one to another in the transverse direction
of the article. In consequence, these segments of the elastic
members in the transversely opposite side edge zones 24 have no
more contractility. In general, the step of cutting the elastic
members 19 is mechanically achieved in a mechanical using a sharp
cutter. Alternatively, the step of such cutting may be carried out
using ultrasonic waves emitted from an ultrasonic wave apparatus
comprising an anvil and a horn The ultrasonic wave treatment allows
the elastic members to be cut or deteriorated without cutting the
base sheet 17. An equivalent effect may be obtained by coating the
target regions of the base sheet 17 with hot melt adhesive and
hardening the adhesive to make these target regions stiff.
[0060] The slits 44 function not only to deprive the elastic
members 19 of contractility thereof but also to facilitate the
front waist region 12 to be torn off from the rear waist region 13.
Particularly in order to facilitate the front waist region 12 to be
torn off from the rear waist region 13, at least the row of slits
44a adjacent the seam line 41 preferably extends from the upper
edge to the lower edge of the front waist region 12. Each of the
reinforcing layers 45 has a sufficiently large contour size to
cover a generally inner half of the side edge zone 24 on the outer
surface of the front waist region 12 and the side edge portion of
the intermediate zone 24. The fastener means 21 are permanently
bonded to these reinforcing layers 45 in the vicinity of the
transversely opposite side edge zones 24 of the front waist region
12.
[0061] The ear flaps 40 are formed from a sheet material such as a
fibrous nonwoven fabric having a tensile strength at least equal to
the tensile strength of the base sheet 17 and preferably having a
stiffness higher than the stiffness of the respective sheet
materials constituting the base sheet 17. Unlike the embodiment as
illustrated, it is also possible to form these ear flaps 40
integrally with the rear waist region 13 from the same material as
that of the rear waist region 13.
[0062] The reinforcing layer 45 may be formed by bonding a sheet
material having an appropriate strength and stiffness such as a
fibrous nonwoven sheet or plastic film to the base sheet 17 using
hot melt adhesive or welding technique such as heat- or
sonic-sealing. Alternatively, the base sheet 17 may be coated with
hot melt adhesive and this hot melt adhesive may be hardened to
form the reinforcing layer 45. In the latter case, hot melt
adhesive is preferably applied on the inner surface of the nonwoven
sheet 25 constituting the base sheet 17. These reinforcing layers
45 reinforce at least partially the regions in which the fastener
means 21 are laid as well as the regions in which the slits 44 are
formed and thereby effectively prevent the fastener means from
being deformed and prevent the slit-formed regions from being
broken. In this way, these reinforcing layers 45 stabilize the
engagement between the fastener means 21, 22.
[0063] While the process for making the article according to the
third embodiment of the invention including the step of depriving
the elastic members 19 of contractility in the transversely
opposite side edge zones 24 is not illustrated, the process for
making the article according to the first embodiment of the
invention may be utilized except the formation of the slits 44 and
attachment of the reinforcing layers 45. The process for making the
third embodiment will be readily understood from the description
given hereinabove of the article, so description of the process for
making the third embodiment is eliminated here.
[0064] The article according to this embodiment can be easily
converted to the open type diaper, if desired, merely by tearing
the front waist region 12 off from the rear waist region 13 along
the slits 44a serving as tear off guide.
[0065] Deprivation of the elastic members 19 of contractility by
the slits 44 as well as the formation of the reinforcing layers 45
may be adopted in the first and second embodiments. Furthermore,
the features of the first, second and third embodiments may be
appropriately combined to obtain an alternative embodiment not
illustrated.
* * * * *