U.S. patent application number 12/739594 was filed with the patent office on 2010-10-14 for method of producing an absorbent garment, and an absorbent garment produced according to the method.
This patent application is currently assigned to SCA Hygiene Products AB. Invention is credited to Elisabeth Lakso.
Application Number | 20100262110 12/739594 |
Document ID | / |
Family ID | 40638935 |
Filed Date | 2010-10-14 |
United States Patent
Application |
20100262110 |
Kind Code |
A1 |
Lakso; Elisabeth |
October 14, 2010 |
METHOD OF PRODUCING AN ABSORBENT GARMENT, AND AN ABSORBENT GARMENT
PRODUCED ACCORDING TO THE METHOD
Abstract
A method for continuously producing absorbent garments includes
forming a continuous multi-component production web; and cutting
individual garments from the production web. The production web is
formed by: a) feeding a first elastic web in a travelling
direction; b) stretching the first elastic web by 35-250% in the
travelling direction; c) intermittently laying down absorbent cores
in an intermediate zone extending in a travelling direction of the
production web; d) feeding a continuous web of liquid permeable
material in the travelling direction and covering the absorbent
cores with the continuous web of liquid permeable material; and e)
bonding the first elastic web to the continuous web of liquid
permeable material in a first lateral zone on a side of the
intermediate zone of the production web. In addition, an absorbent
garment has a continuous liquid permeable layer.
Inventors: |
Lakso; Elisabeth;
(Stenungsund, SE) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
SCA Hygiene Products AB
Goteborg
SE
|
Family ID: |
40638935 |
Appl. No.: |
12/739594 |
Filed: |
November 14, 2007 |
PCT Filed: |
November 14, 2007 |
PCT NO: |
PCT/SE07/01009 |
371 Date: |
April 23, 2010 |
Current U.S.
Class: |
604/385.3 ;
156/160; 156/269; 156/73.4 |
Current CPC
Class: |
Y10T 156/1084 20150115;
A61F 13/49011 20130101; A61F 13/15593 20130101; A61F 13/15699
20130101; A61F 13/4906 20130101; A61F 13/51305 20130101; A61F
13/51113 20130101; A61F 2013/153 20130101 |
Class at
Publication: |
604/385.3 ;
156/269; 156/73.4; 156/160 |
International
Class: |
A61F 13/15 20060101
A61F013/15; B32B 37/00 20060101 B32B037/00; B32B 37/06 20060101
B32B037/06 |
Claims
1. A method for continuously producing absorbent garments
comprising (i) forming a continuous multi-component production web,
the production web having an intermediate zone extending in a
travelling direction and a first lateral zone and a second lateral
zone on each side of the intermediate zone, each lateral zone
including an edge zone extending along an edge of the production
web; and (ii) cutting individual garments from the production web,
wherein the (i) comprises: a) intermittently laying down absorbent
cores in the intermediate zone of the production web; b) feeding a
continuous web of liquid permeable material in the travelling
direction and covering the absorbent cores with the continuous web
of liquid permeable material, the continuous web of liquid
permeable material having a width at least corresponding to the
width of the production web between the edge zones and having a
first side facing the absorbent cores and a second side facing away
from the absorbent cores; c) feeding a first elastic web in the
travelling direction; d) stretching the first elastic web by
35-250% in the travelling direction; e) bonding the first elastic
web to the continuous web of liquid permeable material in the first
lateral zone of the production web, the first elastic web being
bonded to the first or second side of the continuous web of liquid
permeable material before or after application of the continuous
web of liquid permeable material to the absorbent cores.
2. The method according to claim 1, wherein the (i) further
comprises: f) feeding a second elastic web in the travelling
direction; g) stretching the second elastic web by 35-250% in the
travelling direction; and h) bonding the second elastic web to the
continuous web of liquid permeable material in the second lateral
zone of the production web.
3. The method according to claim 2, wherein the first and second
elastic webs are bonded to the continuous web of liquid permeable
material with a gap between the first and second elastic webs in
the intermediate zone of the production web.
4. The method according to claim 1, wherein the continuous web of
liquid permeable material is a nonwoven web.
5. The method according to claim 2, wherein at least one of the
first and second elastic webs comprises an elastic film.
6. The method according to claim 2, wherein at least one of the
first and second elastic webs comprises an elastic nonwoven
material.
7. The method according to claim 2, wherein at least one of the
first and second elastic webs is a laminate of an elastic film and
a nonwoven layer and is bonded to the continuous web of liquid
permeable material with the elastic film facing the continuous web
of liquid permeable material.
8. The method according to claim 2, wherein at least one of the
first and second elastic webs comprises a stretch-activated elastic
laminate.
9. The method according to claim 2, wherein at least one of the
first and second elastic webs comprises a stretch-bonded elastic
laminate.
10. The method according to claim 1, wherein the cores are at least
partially covered with a liquid impermeable material on a surface
of the cores facing away from the continuous web of liquid
permeable material.
11. The method according to claim 10, wherein the cores are applied
and bonded to the liquid impermeable material before joining the
cores with the continuous web of liquid permeable material.
12. The method according to claim 11, wherein the cores are turned
and/or rotated after being bonded to the liquid impermeable
material and are brought into a facing relationship with the
continuous web of liquid permeable material and are applied to the
continuous web of liquid permeable material with the longitudinal
direction of the cores aligned with the cross-machine direction of
the production web.
13. The method according to claim 1, wherein a leg elastic member
is attached to the production web.
14. The method according to claim 1, wherein the production web is
provided with an elastic waist band along at least one edge of the
production web.
15. The method according to claim 14, wherein the elastic waist
band comprises a portion of the continuous web of liquid permeable
material.
16. The method according to claim 14, wherein the elastic waist
band is joined to the production web as a separate component.
17. The method according to claim 2, wherein at least one of the
first and second elastic webs is adhesively bonded to the
continuous web of liquid permeable material.
18. The method according to claim 2, wherein at least one of the
first and second elastic webs is thermally or ultrasonically bonded
to the continuous web of liquid permeable material.
19. The method according to claim 1, wherein the (i) further
comprises treating the continuous web of liquid permeable material
to provide a continuous web of liquid permeable material with areas
of different hydrophilicity or hydrophobicity.
20. The method according to claim 19, wherein the continuous web of
liquid permeable material comprises a hydrophobic polymeric
material and the continuous web of liquid permeable material is
subjected to a hydrophilicity treatment in a selected portion or
portions of the continuous web of liquid permeable material
coinciding with the absorbent cores in the production web.
21. The method according to claim 1, wherein the (i) further
comprises one or more of the following production steps: a)
applying raised barriers; b) cutting the production web to form leg
openings; c) folding the production web; d) applying fastening
elements to the production web; e) forming side joins in the folded
web, and f) separating individual pant-type absorbent garments from
the production web by cutting at the side joins.
22. An absorbent garment comprising a chassis structure comprising
a front panel having a front end edge and first and second side
edges, a back panel having a back end edge and first and second
side edges, a crotch panel being arranged between the front and
back panels, elasticated front and back waist panels being arranged
along the front and back end edges of the front and back panels,
and a core component being integrated with the chassis structure
and forming an integral part of the absorbent garment, the chassis
structure including a liquid permeable material having a garment
facing side and a user facing side and forming a liquid permeable
surface layer in the garment, wherein the liquid permeable material
extends continuously between the front end edge and the back end
edge and at least one of the front panel and the back panel
comprises an elastic web that has been bonded to the liquid
permeable material with the elastic web stretched by 35-250% in at
least one direction.
23. The absorbent garment according to claim 22, wherein the liquid
permeable material forms part of one or both of the elasticated
front and back waist panels.
24. The absorbent garment according to claim 22, wherein an elastic
web has been bonded to each of the front panel and the back panel
the garment having a gap between the elastic webs in the crotch
panel.
25. The absorbent garment according to claim 22, wherein the first
and second side edges of the front panel are joined by edge joins
to the corresponding first and second side edges of the back
panel.
26. The absorbent garment according to claim 22, wherein the
elastic waist panels comprise elastic elements that are attached to
the liquid-permeable material.
27. The absorbent garment according to claim 26, wherein the
elastic elements are attached to the outer garment-facing side of
the liquid-permeable material.
28. The absorbent garment according to claim 26, wherein the
elastic elements are attached to the user-facing side of the
liquid-permeable material.
29. The absorbent garment according to claim 26, wherein the
liquid-permeable material is folded over to cover the elastic
elements and is secured in the folded over configuration.
30. The absorbent garment according to claim 22, wherein the
elastic waist panels comprise a portion of the at least one elastic
web.
31. The absorbent garment according to claim 22, wherein the liquid
permeable material is treated to render it more hydrophilic or less
hydrophobic in an area of the liquid permeable material that covers
the absorbent core than in an area of the liquid permeable material
that is located outside of the absorbent core.
Description
TECHNICAL FIELD
[0001] The invention relates to a method for continuously producing
absorbent garments, the method comprising forming a continuous
multi-component production web and cutting individual garments from
the production web. The invention also concerns an absorbent
garment that may be produced according to the method.
BACKGROUND ART
[0002] Absorbent garments, particularly disposable pant-type
absorbent garments include a pant-shaped chassis structure and an
absorbent core component permanently integrated with the chassis. A
major objective when designing pant garments is to make them
resemble ordinary underwear as closely as possible. For this
reason, the garment chassis usually comprises a material that is
elastically stretchable, at least in the areas intended to be
applied over the wearer's hips. In addition, absorbent garments
such as pant diapers, sanitary pants and incontinence pants are
designed to fit comfortably and snugly about the wearer and it is
desired that they have a minimum of seams and joins that could
cause discomfort such as chafing.
[0003] Further, absorbent pant-type garments should be capable of
being pulled up and down over the hips of the wearer in the manner
of a pair of underpants to allow the wearer or caregiver to easily
remove a soiled garment and to replace it with a new clean garment.
A particular problem with pant-type garments is that seams and
joins running in a direction parallel to the waist edge of the
garment may rupture when the user or a care-giver is pulling on the
garment. In order to avoid this problem, it has to be ascertained
that joins between different parts of the disposable pant-type
garment are sufficiently strong to withstand the forces arising
during normal use. However, strong seals and joins are commonly
obtained by increasing the bonding area and/or by using more binder
materials or severe binding conditions, resulting in stiffer and
more uncomfortable joins.
[0004] A further requirement of particular importance for
disposable garments is that the garment can be produced by an
economically efficient process, involving as few process steps and
components as possible.
[0005] Hence, there exists a continuing need for an improved
process of making a pant-type absorbent garment having a chassis
including one or more elastically stretchable components.
[0006] Accordingly, an object of the invention is to provide a
simple and economic method for producing an absorbent garment such
as an elastically stretchable pant-type garment.
DISCLOSURE OF INVENTION
[0007] In accordance with the invention, there is provided method
for continuously producing absorbent garments comprising forming a
continuous multi-component production web, the production web
having an intermediate zone extending in a travelling direction and
a first and a second lateral zone on each side of the intermediate
zone each lateral zone including an edge zone extending along an
edge of the production web; and cutting individual garments from
the production web.
[0008] The method for forming the production web comprises the
steps of: [0009] a) feeding a first elastic web in the travelling
direction; [0010] b) stretching the first elastic web by 35-250% in
the travelling direction; [0011] c) intermittently laying down
absorbent cores in the intermediate zone of the production web;
[0012] c) feeding a continuous web of liquid permeable material in
the travelling direction and covering the absorbent cores with the
continuous web of liquid permeable material, the continuous web of
liquid permeable material having a width at least corresponding to
the width of the production web between the edge zones; [0013] e)
bonding the first elastic web to the continuous web of liquid
permeable material in the first lateral zone of the production web,
the first elastic web being applied to the production web before or
after application of the continuous web of liquid permeable
material.
[0014] The method steps may be carried out in any order as long as
the continuous web of liquid permeable material forms an inner
liquid permeable surface in the assembled absorbent garment.
[0015] The method according to the invention offers a highly
economical and efficient way of producing disposable absorbent
garments. The finished garments in accordance with the invention
have a tailored appearance with a soft continuous inner
body-contacting layer and an outer surface that may be a nonwoven
or elastic film layer, as desired. The method makes it possible to
use a minimum of material layers and components that have to be
joined to each other thus reducing production times as well as
production costs.
[0016] The term absorbent garment as used herein, refers to all
kinds of absorbent hygienic garments that are worn as a pair of
underpants and that have a waist opening and two leg openings.
Garments according to the invention include pant-diapers and
open-type diapers for all kinds of users as well as absorbent
hygienic panties for feminine protection and incontinence.
[0017] In this context, an elastic material is defined as a
material having a permanent elongation after relaxation of less
than 10% after the material has been subjected to an elongation of
30% in the elasticity test specified hereinafter.
[0018] A non-elastic material is a material that does not fall
within the definition of an elastic material. Accordingly, a
non-elastic material as used herein is a material that may be
stretchable or non-stretchable. In the case of a stretchable
material, the material has a permanent elongation after stretching
and relaxation of more than 10% after having been subjected to an
elongation of 30% as determined according to the elasticity
test.
[0019] The elastic web may be adhesively bonded to the continuous
web of liquid permeable material or may be thermally or
ultrasonically bonded to the continuous web of liquid permeable
material.
[0020] Thermal or ultrasonical bonding can be in the form of
individual bond elements such as spot bonds or line bonds or can be
in the form of a continuous bond pattern. By selecting a bond
pattern of sparsely distributed spot bonds, it is possible to
achieve a higher flexibility in the resulting laminate than with a
pattern of bonds occupying a large proportion of the interface
between the bonded layers.
[0021] The method according to the invention may further include
the steps of: [0022] f) feeding a second elastic web in the
travelling direction; [0023] g) stretching the second elastic web
by 35-250% in the travelling direction; and [0024] h) laminating
the second elastic web to the continuous web of liquid permeable
material in the second lateral zone of the production web.
[0025] The elastic web or webs may be elastic film, elastic
nonwoven or an elastic laminate comprising at least one elastic
film and/or elastic nonwoven material. The elastic webs may form
elastic waist panels and elastic front and back panels in the
finished pant-type absorbent garment. In one embodiment of the
invention, the elastic web is a laminate of an elastic film and a
nonwoven layer and the elastic web is bonded to the continuous web
of liquid permeable material with the elastic film facing the
continuous web of liquid permeable material.
[0026] An elastic material that has previously been used to form
elastic panels in absorbent garments such as pant-type diapers is a
laminate comprising an elastic film sandwiched between two layers
of non-elastic nonwoven. In order to render the laminate
elastically stretchable, it is subjected to an activation
treatment. A three-layer, activated laminate is disclosed in
International Patent Application No. WO 03/047488. The activated
laminate is produced by incrementally stretching an elastic film
layer between two non-elastic cloth-like layers. Incremental
stretching is carried out by passing the laminate between
intermeshing gear rollers. Activation of elastic laminates by
incremental stretching is also disclosed in U.S. Pat. Nos.
5,143,679, 5,156,793 5,167,897, 5,422,172, 5,592,690, 5,634,216 and
5,861,074. The non-elastic cloth-like layers are fully or partially
broken or torn during the activation process so that the elasticity
of the laminate after activation is determined mainly by the
elasticity of the elastic film layer. In the three-layer laminate
in WO 03/047488, the non-elastic layers are completely broken so
that the elasticity of the activated laminate is substantially the
same as the elasticity of the elastic film layer.
[0027] The disclosed laminates have excellent comfort properties
and are soft, breathable and elastic. Unfortunately, the activation
process reduces the tensile strength and puncture resistance of the
material so that when used as a chassis component in a disposable
pant garment, the material is easily torn when exposed to the
forces arising when putting on or taking off the pant garment. In
order to increase the tensional strength of an activated laminate
and to overcome the tearing problem, it has been proposed in
PCT/SE2006/000563 to bond a stretch-activated two-layer laminate
comprising a nonwoven layer and an elastic film layer to a second
reinforcing nonwoven layer while the two-layer laminate is in a
stretched state.
[0028] For the purpose of the invention, it is also possible to use
stretch-bonded elastic laminates comprising an elastic film or
nonwoven web that has been bonded to at least one non-elastic layer
with the elastic layer being stretched in at least one direction
during the bonding step.
[0029] Another type of elastic laminates that could be used in the
method according to the invention is "neck bonded" laminates, which
are laminates in which an elastic material is bonded to a
non-elastic material while the non-elastic material is extended
under conditions reducing its width. A neck bonded laminate is a
composite material having at least two layers in which one layer is
a necked, non-elastic layer and the other layer is an elastic
layer.
[0030] The elastic film used for producing the elastic laminates
may be of any suitable elastic polymer, natural or synthetic. One
example of an elastic film that has proven to provide good
elasticity and breathability is an apertured three-layer
elastomeric film with the composition
polyethylene-styrene/ethylene/butadiene/styrene-polyethylene
(PE-SEBS-PE).
[0031] The elastic web or webs used in the process in accordance
with the invention may be composed of a layer of fibrous material
and an elastic layer. The fibrous layer is preferably chosen so
that it provides a soft and cloth-like feel and appearance to the
laminate. Examples of suitable materials are meltblown webs,
spunbond materials, and creped nonwovens. Creped nonwovens
generally have greater extensibility and flexibility than
non-creped nonwovens. By using a creped nonwoven, the laminate will
be more conformable and extensible than is possible with a
non-creped nonwoven.
[0032] The basis weight of the nonwoven web used in the elastic
laminate is suitably from 10-80 g/m.sup.2 and preferably from 10-30
g/m.sup.2. Examples of suitable polymers used in the fibrous
material are polyesters, polyethylene, polypropylene and other
polyolefin homopolymers and copolymers. Natural fibres, for example
cotton, may also be used as long as they provide the desired
properties. A mixture of polymers can contribute to a higher
flexibility of the nonwoven layer and give the nonwoven material a
higher elongation at maximum load. A mixture of polyethylene and
polypropylene polymers has proven to provide good results in this
respect. However, nonwovens having different fibre mixtures may
also be used.
[0033] The elastic layer is preferably an apertured elastic film.
The elastic layer may have a basis weight of between 10 and 120
g/m.sup.2, preferably between 15 and 60 g/m.sup.2. The elastic
layer may be of any suitable elastic polymer, natural or synthetic.
Some examples of useful materials for the elastic layer are low
crystallinity polyethylenes, metallocene-catalyzed low
crystallinity polyethylenes, ethylene vinyl acetate copolymers
(EVA), polyurethane, polyisoprene, butadiene-styrene copolymers,
styrene block copolymers, such as styrene/isoprene/styrene (SIS),
styrene/butadiene/styrene (SBS), or
styrene/ethylene-butadiene/styrene block copolymer. Blends of these
polymers may also be used as well as other modifying elastomeric or
non-elastomeric materials. One example of a suitable elastic film
is an apertured three-layer elastomeric film with the composition
polyethylene-styrene/ethylene/butadiene/styrene-polyethylene
(PE-SEBS-PE).
[0034] In accordance with the invention, the continuous web of
liquid permeable material constitutes a reinforcement layer for the
elastic web. Hence, it is possible to use an elastic two-layer
laminate or an elastic film layer to elasticise the absorbent
garment instead of the prior art three-layer laminates. An elastic
two-layer laminate may be manufactured and activated according to
either of the methods disclosed in WO 03/047488 or EP 0 715 351 by
applying the nonwoven web to one side of the film. The nonwoven web
and the film may be extrusion bonded or may be bonded by adhesive.
The laminate is incrementally stretched to activate the elasticity
of the film layer. Incremental stretching can be made to a point
below the elongation at peak load of the nonwoven web to retain
some strength in the nonwoven web. Alternatively, the stretching
may be carried out so that the nonwoven is completely torn, as
disclosed in WO 03/047488.
[0035] When laminating a two-layer stretch-activated laminate to
the continuous web of liquid permeable material, the two-layer
laminate is preferably bonded to the continuous web of liquid
permeable material with the film side of the laminate facing the
continuous web of liquid permeable material. Thereby, a three-layer
laminate is created having a smooth face on the surface where the
two-layer laminate is arranged and a somewhat gathered, puckered
face on the opposing surface, where the continuous web of liquid
permeable material is arranged. In this manner, an absorbent
garment having a smooth surface in contact with any clothing worn
over the absorbent garment is obtained. The smooth surface of the
laminate is aesthetically pleasing and will be less conspicuous
when the absorbent article is worn under thin or tight-fitting
garments.
[0036] Before laminating the elastic web to the continuous web of
liquid permeable material, the elastic web is stretched, preferably
in the travelling direction, or machine direction, MD by 35-250% of
its initial, non-stretched extension and is held in the stretched
state during the lamination step. By choosing and controlling the
amount of stretch, it is possible to obtain a selected elasticity
in the end product. The elastic web is preferably stretched by
35-180% of its non-stretched extension, more preferably by 50-150%
of its non-stretched extension and most preferably by 70-120% of
its non-stretched extension during lamination with the continuous
web of liquid permeable material.
[0037] The amount of stretching of the elastic web is specified as
a percentage of the initial, non-stretched extension of the
laminate in the direction of stretch. Accordingly, a laminate
having a first, non-stretched length of 1 m and being stretched by
50% has a second, stretched length of 1.5 m.
[0038] The elastic web can be adhesively bonded to the continuous
web of liquid permeable material. Alternatively, the elastic web
can be thermally or ultrasonically bonded to the continuous web of
liquid permeable material. Thermal or ultrasonical bonding can be
in the form of discreet bonds such as spot bonds or line bonds. By
selecting a bond pattern of sparsely distributed spot bonds, it is
possible to obtain a material having higher flexibility and
conformability than with a bond pattern occupying a large
proportion of the interface between the bonded layers.
[0039] A major advantage of the method according to the invention
is that it is possible to use a single layer of elastic material
such as an elastic film or a two-layer film/nonwoven laminate and
still obtain a sufficiently strong elastic panel in the finished
absorbent garment. When a two-layer film/nonwoven laminate is used
and placed with the nonwoven layer on the outside of the absorbent
garment, the overall appearance of the garment will be that of a
textile panty with soft and comfortable inner and outer surfaces.
The elimination of a layer of material in the garment constitutes a
considerable material saving and a corresponding saving of
production costs.
[0040] The method according to the invention preferably comprises
applying a liquid impermeable material on one surface of each
absorbent core.
[0041] The absorbent core may be bonded to a web of liquid
impermeable material, the liquid impermeable web then being cut
between the cores into core components comprising an absorbent core
and a liquid impermeable barrier layer. Alternatively, the cores
are bonded to the web of liquid impermeable material which is
subsequently introduced into the production web, without cutting
individual core components from the web.
[0042] The core components are transferred to the production web
and applied to the production web with the liquid impermeable
barrier layer facing down on the production web. Depending on how
the cores are oriented during bonding to the web of liquid
impermeable material, the core components may have to be turned
over and/or rotated so that they are incorporated in the production
web with the liquid impermeable barrier layers facing away from the
continuous web of liquid permeable material and with the cores
applied with the longitudinal direction of the cores in the
cross-machine direction of the production web. The liquid
impermeable barrier layer should have a width that is smaller than
the width of the continuous web of liquid permeable material.
Accordingly, the liquid impermeable barrier layer should not extend
all the way to the edges of the production web and should
preferably have the same or only slightly greater extension in the
cross-machine direction, CD, of the production web than the cores.
The CD extension of the liquid impermeable barrier layer may
preferably not be more than 4 cm greater than the CD extension of
the cores.
[0043] Alternatively, the liquid impermeable material may be joined
to the production web before the absorbent cores joined to the
production web.
[0044] The core components may include further elements such as a
supplementary topsheet material which may be a fluid acquisition
material, liquid transport members, elastic members,
shape-stabilizing members, shaping elements or the like. The
components included in the core components can be connected to one
another in a conventional manner, for example by adhesive bonding,
ultrasonic welding or thermowelding.
[0045] The method according to the invention may further include
attaching one or more leg elastic members to the production web.
The leg elastic members may be applied to the continuous web of
liquid permeable material. A further option is to apply the leg
elastic members to a separate carrier material that is then
incorporated into the production web.
[0046] Leg elastic may be applied in any known manner and using any
known and commonly used elastic materials. One example of a
suitable method of arranging leg elastics is disclosed in WO
2004/078083. When the leg elastic is applied so that it extends
across the cores, it may be advantageous to deactivate parts of the
elastic member or members extending over the cores. Deactivation
may be accomplished in any known manner such as by treating the
elastic members with chemicals or heat or by simply cutting the
elastic members.
[0047] The method according to the invention preferably also
includes arranging an elastic waist band along at least one of the
edges of the production web. A waist band can be formed by
attaching discrete or continuous elastic elements along at least
one edge of the continuous web of liquid permeable material and
optionally covering the elastic elements with a nonwoven web which
may be a folded-over portion of the continuous web of liquid
permeable material or a separate nonwoven strip.
[0048] An elastic waist band can alternatively be joined to the
production web as a separate component that has been prefabricated
or that is manufactured in line with the production web.
[0049] The elastic waist band is preferably continuously joined to
or arranged on the production web and may comprise an elastic band
of any suitable kind of material such as elastic laminates, elastic
foam strips, elastic nonwovens, non-elastic materials that have
been elasticised with elastic threads or strings, etc. A commonly
used elastic waist band is made by attaching elastic elements such
as threads, bands or strings in a pre-tensioned state between two
layers of nonwoven, non-elastic material. All commonly used elastic
materials including natural or synthetic rubber, elastic foam, etc.
can be employed. A waist band of this type may include two separate
layers of nonwoven or may comprise a single layer of nonwoven
material that is folded into a two-layer structure.
[0050] Preferably, the elastic waist band includes a portion of the
continuous web of liquid permeable material. An advantage of using
the continuous web of liquid permeable material when forming the
waist band is that the number of stiff and uncomfortable seams and
joins can be reduced, giving the garment a soft and tailored
appearance and feel. It is particularly preferred to arrange the
waist band so that the inner surface of the hygienic garment is
smooth without any potentially chafing irregularities.
[0051] The elastic waist band may include one or more components of
the production web such as the first continuous web of liquid
permeable material. In these embodiments, the elastic waist band
may include an edge portion of an elastic or non-elastic part of
the production web. In a particularly preferred embodiment, the
elastic waist band is formed by attaching elastic elements to an
edge portion of the first continuous web of liquid permeable
material web and subsequently folding the continuous web of liquid
permeable material to cover the elastic elements. It is also
possible to attach elastic elements to an edge portion of the
production web and leave the elastic elements non-covered, or
covered by a separate web. If the elastic waist band incorporates
an elastic web arranged at an edge portion of the first continuous
web of liquid permeable material, the elastic web may be folded to
create an edge portion having higher elastic retraction force than
the non-folded portion of the part of the production web including
only a single elastic web. The folded elastic web may be
supplemented by additional elastic elements, if desired.
[0052] The method according to the invention may further include
any conventional pant-forming production steps such as one or more
of the following: [0053] a) applying raised barriers; [0054] b)
cutting the production web to form leg openings; [0055] c) folding
the production web; [0056] d) applying fastening elements to the
production web; [0057] e) forming side joins in the folded web, and
[0058] f) separating individual pant-type absorbent garments from
the production web by cutting at the side joins.
[0059] Raised barriers are commonly used in diapers and similar
absorbent garments and. The barriers are attached to the inner
surface of the absorbent garment and are often made of hydrophobic
nonwoven material. The raised barriers are often elasticated in
order to hold the barriers in the raised position.
[0060] As an alternative to the formation of side joins, the method
may include attaching fastening elements to the production web or
to the separated individual absorbent garments.
[0061] The invention also offers an absorbent garment comprising a
chassis structure comprising a front panel having a front end edge
and first and second side edges, a back panel having a back end
edge and first and second side edges and a crotch panel being
arranged between the front and back panels and elasticated front
and back waist panels being arranged along the front and back end
edges of the front and back panels, and a core component being
integrated with the chassis structure and forming an integral part
of the absorbent garment, the chassis structure including a liquid
permeable material having a garment facing side and a user facing
side and forming a liquid permeable surface layer in the garment.
The liquid-permeable material extends continuously between the
front end edge and the back end edge and at least one of the front
panel and the back panel comprises an elastic web that has been
bonded to the liquid permeable material with the elastic web
stretched by 35-250% in at least one direction.
[0062] The elastic web in the front and back panels preferably
extends from the waist edges all the way to the leg openings of the
garment.
[0063] According to an embodiment of the invention, the liquid
permeable material forms part of one or both of the elasticated
front and back waist panels.
[0064] An elastic web may have been bonded to each of the front
panel and the back panel, the garment having a gap between the
elastic webs in the crotch panel (58).
[0065] The absorbent garment may be a pant-type garment having the
first and second side edges of the front panel being joined by edge
joins to the corresponding first and second side edges of the back
panel.
[0066] The elastic waist panels of the absorbent garment according
to the invention may comprise elastic elements that are attached to
the liquid-permeable material either on the outer garment-facing
side of the liquid-permeable material or on the inner, user-facing
side of the liquid-permeable material. The liquid-permeable
material may be folded over to cover the elastic elements and may
be secured in the folded over configuration by adhesive,
thermobonding or ultrasonic welding. The elastic waist panels may
comprise a portion of the at least one elastic web.
[0067] In accordance with the invention, the absorbent garment has
a reinforcing member which is the continuous inner liquid-permeable
surface layer or topsheet. The continuous inner surface layer is
preferably a non-elastic material and preferably comprises a layer
of nonwoven material. Useful materials include meltspun, meltblown
and carded nonwovens. The materials may be thermobonded,
hydroentangled, needled, thru-air bonded, or bonded with a bonding
agent, as desired. The use of a continuous inner layer in the
garment reduces the risk of breaking seams and joins between other
components in the garment and of tearing materials that have low
tensile strength such as stretch-activated elastic segments when
putting on the garment. Moreover, seams and joins between
components that are bridged by the continuous material can be made
less strong, thus reducing welding times in the production process.
Further, when less severe bonding conditions and less overlap
between materials have to be used, the seams and joins can be made
softer and less stiff than in conventional absorbent garments,
implying that conformability and comfort of the garment is improved
without risking that the garment will break or fall apart during
production and handling.
[0068] A smooth and continuous inner surface is also beneficial in
that it enhances wearer comfort and reduces the risk of chafing and
skin irritation. However, it is within the scope of the invention
to place one or both of the elastic webs on the inside of the
absorbent garment.
[0069] The garment may be a pant-type garment having the first and
second side edges of the front panel joined by edge joins to the
corresponding first and second side edges of the back panel.
Alternatively, the garment may be of the open type which is
provided with fastening elements that are used to fasten together
the front and back panels of the garment when it is being put on a
user.
[0070] The elastic waist panels may comprise elastic elements that
are attached to the liquid-permeable material. The elastic elements
may be attached to the garment-facing side of the liquid-permeable
material or to the user-facing side of the liquid-permeable
material. The liquid-permeable material may be folded over to cover
the elastic elements or the elastic elements may be uncovered or
covered by a separate material.
[0071] Further, the elastic waist panels may comprise a portion of
the at least one elastic web.
BRIEF DESCRIPTION OF THE DRAWINGS
[0072] The invention will in the following be described in greater
detail with reference to the appended drawings, wherein
[0073] FIG. 1 shows schematically a method for producing pant-type
absorbent garments in accordance with the invention;
[0074] FIG. 2 shows schematically the production of core
components;
[0075] FIG. 3 shows a cross section through a production web
according to a first embodiment of the invention;
[0076] FIG. 4 shows a cross section through a production web
according to a second embodiment of the invention;
[0077] FIG. 5 shows a pant-type diaper in accordance with the
invention in a flat state, and
[0078] FIG. 6 shows the diaper in FIG. 5 with closed side
joins.
DETAILED DESCRIPTION OF THE INVENTION
[0079] FIG. 1 shows a method for continuously producing absorbent
garments, in particular pant-type diapers, although open-type
diapers may be formed by the same general method. The method
involves forming a continuous multi-component production web and
cutting individual diapers from the production web.
[0080] In FIG. 1, a diaper chassis structure is formed from a
compound production web 22, comprising a continuous base web 23 of
liquid-permeable material and first and second elastic webs 24,25
and first and second waist elastic elements 30,31. The elastic webs
24,25 may be elastic films, elastic nonwoven webs or elastic
laminates, as previously disclosed.
[0081] The production web 22 has an intermediate zone 2 extending
in a travelling direction, the machine direction, MD and a first
and a second lateral zone 3,4 on each side of the intermediate zone
2 each lateral zone including an edge zone 6,7 extending along an
edge 8,9 of the production web 22. The edge zones are the parts of
the lateral zones 3,4 closest to the side edges 8,9 of the
production web 22.
[0082] The production web 22 is shown to have the different zones
2,3,4 symmetrically distributed in the cross machine direction CD
with the intermediate zone 2 centrally located between the lateral
zones 3,4 and the lateral zones 3,4 having equal widths. However,
for other embodiments of the invention, the intermediate zone may
be offset towards one of the side edges 8,9 of the continuous base
web 23 implying that the lateral zones 3,4 have different
widths.
[0083] As shown in FIG. 1, first and second elastic webs 24,25 are
fed between two rollers 26,27 in the MD. The elastic webs 24,25 are
stretched at least in the machine direction (MD) by 35-250% of
their initial, non-stretched extension. As shown in FIG. 1,
stretching may be carried out by passing the webs between a pair of
rollers 26,27 driven at different speeds. By controlling the amount
of stretch, a predetermined elasticity can be obtained in the
finished garment chassis. The elastic webs 24,25 are preferably
stretched by 35-180% of their non-stretched extension, more
preferably by 50-150% of their non-stretched extension and most
preferably by 70-120% of their non-stretched extension. The elastic
webs 24,25 need not be stretched to the same extent if different
elasticity is desired in different portions of the chassis
structure. It is also possible to use different types of elastic
materials in the elastic webs 24,25.
[0084] The degree of stretching of the elastic webs 24,25 during
the formation of the production web 22 is a major means of
controlling the elasticity in the portions of the production web 22
where the elastic webs 24,25 are attached.
[0085] The stretched elastic webs 24,25 are shown to be laminated
to the continuous base web 23 in the lateral zones 3,4 of the
production web after absorbent cores 33 have been laid down on the
elastic webs 24,25 in the intermediate zone of the production web.
Alternatively, the elastic webs 24,25 may be bonded to the
continuous base web 23 after the base web has been applied over the
absorbent cores 33 or the elastic webs 24,25 may be attached to the
continuous base web 23 before the continuous base web 23 is applied
over the absorbent cores 33. Accordingly, the elastic webs 24,25
may be applied to either side of the continuous base web 23.
Lamination may be carried out by means of any suitable lamination
process such as by using a binder, by thermo-bonding, ultra-sonic
welding, etc.
[0086] In the embodiment shown in FIG. 1, the continuous base web
23 is fed in the MD and is applied over the absorbent cores 33. The
continuous base web 23 has a width at corresponding to the width of
the production web 22. In alternative embodiments, where a waist
band is added to the production web 22, the continuous base web 23
may have a width corresponding to the width of the production web
22 between the edge zones 6,7.
[0087] It is preferred to use a nonwoven material having
thermoplastic properties for the continuous base web 23 as a web
containing thermoplastic material can be joined to other components
by thermo-welding and ultrasonic welding techniques. The nonwoven
layer can also be used to form side joins with good tensile
strength. The side joins are preferably breakable side joins, i.e.
welds that may be peeled or torn apart when the garment is removed
after use.
[0088] Core components 32 are produced in a separate process as
shown in FIG. 2 and are intermittently laid down on the production
web 22 as shown in FIG. 1. The core components 32 are placed in the
intermediate zone 2 of the production web 22 with portions of the
core components 32 extending into each lateral zone 3,4. If
desired, the core components 32 may be bonded to the continuous
base web 23 and/or to the elastic webs 24,25 with adhesive or by
any other conventionally employed bonding method.
[0089] The core components 32 may be produced as shown in FIG. 2,
the process including feeding a web 34 of liquid impermeable
material and laying down and bonding absorbent cores 33 to the web
of liquid impermeable material 34. Individual core components 32
are formed by severing the web 34 of liquid impermeable material
between the absorbent cores 33 at a cutting station 29. The cutting
station 29 is shown as a cutting wheel, but may be any kind of
cutting apparatus. It is also conceivable to cut the liquid
impermeable web into a shape corresponding to the shape of the
absorbent core 33 or into any other suitable shape.
[0090] Before joining the core components 32 to the production web
22, the core components 32 are oriented so that the liquid
impermeable barrier material is facing away from the continuous web
of liquid permeable material 23 in the production web 22. Moreover,
the core components 32 are rotated to bring the longitudinal
direction of the cores 33 into alignment with the cross machine
direction, CD of the production web 22.
[0091] The core components in FIG. 2 may, of course, comprise
additional elements as conventional in the art. Accordingly, the
core components may comprise elastic elements, one or more
absorbent members, liquid handling structures, shape retaining
elements, etc. It is to be understood that the construction of the
core component 32 and the absorbent core 33 is by no means limiting
to the invention. Hence, any commonly employed core concepts and
materials may be used in the process according to the invention. In
addition, the core may have any suitable shape and size, as
required by the intended use that the garment is designed for.
[0092] Waist elastic elements 30,31 are attached along the edges
8,9 of the continuous base web 23 in the edge zones 6,7 of the
production web 22 and the elastic elements 30,31 are then covered
by folding the continuous base web 23 over the elastic elements
30,31 to form a waist band along each edge of the production web
22. In the process in FIG. 1, the elastic elements 30,31 are
attached on the side of the continuous base web 23 that will be a
garment-facing side in the absorbent garment and the continuous
base web 23 is then folded over on the garment-facing side of the
continuous base web 23 and bonded in the folded-over configuration
to the continuous base web 23 or to the elastic webs 24,25. In this
manner the side of the continuous base web 23 that will be a
body-facing side in the absorbent garment, can be made smooth and
without discontinuities. However, according to other embodiments of
the invention, the waist elastic elements may be placed on the
bodyfacing side of the continuous base web 23 and may be covered by
a portion of the continuous base web 23 that is folded over towards
the bodyfacing side of the continuous base web 23 to produce a,
seamless garment-facing surface at the waist border of the
garment.
[0093] In the process in FIG. 1, the continuous base web 23 has a
width that is equal to the width of the production web 22. This is
a preferred arrangement since the continuous base web 23 will then
be a carrier web for all components in the production web 22.
Moreover, the continuous base web 23 may be used to form a soft,
comfortable and seam-free inner surface of an absorbent garment
produced from the production web as shown in FIG. 3. An absence of
seams on the inner surface is beneficial in that it reduces the
risk of skin irritation. In any case, by minimising the number of
seams and joins in the absorbent garment, the garment becomes more
flexible and conformable than prior art garments. The continuous
base web 23 will also be a reinforcing member, reducing the risk of
breaking seams and joins between other components in the garment
and of tearing materials that have low tensile strength such as
stretch-activated elastic laminates.
[0094] The elastic webs 24,25 in FIG. 1 are laminated to the
continuous base web 23 in the lateral zones 3,4 of the production
web 22 but cover only a small portion of the edge zones 6,7. This
means that the waist bands in the FIG. 1 embodiment will be formed
mainly from the folded portions of the continuous base web 23 and
the elastic elements 30,31 inside the folds. Waist elastic may
alternatively be formed by applying the elastic webs 24,25 all the
way to one or both edges 8,9 of the production web 22 and folding
the edge portions of the production web 22 to form a waist band
comprising two layers of the elastic web 24,25 and optionally one
or two layers of the continuous base web 23. The waist band may
further be supplemented with additional elastic elements. A further
option is to create a waist band at one or both edges of the
production web 22 by attaching elastic elements to the web and
optionally covering the elastic elements with a separate nonwoven
strip. The elastic elements 30,31 in FIG. 1 are shown as continuous
threads. However, the elastic elements may be any type of elastic
material that is used for elasticating absorbent garments such as
elastic bands and tapes comprising elastic nonwoven, laminates,
film, net, foam, etc. The waist elastic does not have to be
continuous as in FIG. 1 but can be applied in the form of discrete
pieces of material attached intermittently along one or both edges
of the production web 22.
[0095] The production web may also comprise leg elastics applied to
one or more of the continuous base web 23, the core components, the
elastic webs 24,25 or a separate carrier member. The leg elastics
can be any conventionally used elastic elements such as one or more
elastic threads, bands, etc. One suitable way of arranging leg
elastic on a production web is disclosed in WO 2004/078083.
[0096] When the production web 22 has been assembled, a portion 44
is cut out from the production web 22 between the core components
32 to create leg openings 45. The cut-out portions extend in the CD
over the intermediate zone and into each lateral zone. In this
manner, the elastic webs 24, 25 extend all the way to the leg
openings in the finished garment 21. The production web and the
integrated core components 32 are then folded centrally in the
machine direction MD and the web halves are joined in side seams 46
between the core components. Finally, individual pant diapers 21
are cut from the production web.
[0097] Side joins are often arranged in a pant-type garment to
connect the garment's front portion to the rear portion and to form
a pant having a waist opening and leg openings. Usually, the side
joins are intended to be arranged at the user's hips during use of
the absorbent pants, but it is also known to arrange side joins
more to the front of the garment. Side joins that are placed at the
front of the garment may be made after severing individual garments
from the production web. The side joins are preferably designed so
that they can withstand the tensile forces which arise when the
garment is being put on and is being worn, but such that they can
be torn apart or opened in a controlled manner when the absorbent
pants are taken off or to check if the garment needs changing. In
the latter instance, the side joins are preferably reclosable
joins, as known in the art.
[0098] Moreover, if the garment is an open-type diaper of the kind
that is fastened together into a pant-shape when the diaper is put
on a user, the process does not involve forming side seams.
Instead, the process will normally include arranging fastening
elements on the production web or on the garments after they have
been cut from the web. Commonly used fastening elements for
open-type diapers are mating hook-and-loop fasteners or adhesive
fasteners.
[0099] FIG. 3 is a section through the production web 22 taken in
the cross machine direction, CD, before folding of the web and
cutting it into individual absorbent garments. Accordingly, FIG. 3
shows a longitudinal section through an absorbent garment that may
be a pant diaper or a sanitary panty that has not yet been folded
and provided with side seams or may be an open-type diaper.
[0100] When seen as components in an absorbent garment, the
continuous base web 23 forms a liquid permeable topsheet 78 and
front and back elastic waist bands 61. The elastic webs 24,25 that
are laminated to the continuous base web 23 form front and back
panels 56,57 of a chassis structure that also includes a crotch
panel 58 formed from the liquid barrier layer 34 of the core
component 32. FIG. 2 does not show all the different elements of
the core component. The liquid barrier layer 34 may be covered by
an outer crotch nonwoven that is not shown in FIG. 3 or 4. The
outer crotch nonwoven should be chosen to be a non-elastic material
to ensure that the crotch portion of the garment according to the
invention is generally non-elastic.
[0101] FIG. 4 shows a longitudinal section through an absorbent
garment similar to that in FIG. 3 but with the elastic webs 24,25
arranged on the inside or topsheet 78 side of the continuous base
web 23. The elastic webs 24,25 are also shown to extend into the
elastic waist bands 61 and form part of the waist bands 61. The
elastic webs 24,25 are folded in the edge portions 6,7 of the
production web 22 to create the elasticated waist bands 61.
[0102] The elastic webs 24,25 are shown in FIGS. 3 and 4 to extend
in over the absorbent core 33 of the core component 32. However, in
an alternative embodiment, the elastic webs 24,25 may be applied to
the continuous base web 23 without overlap with the absorbent core
33. Preferably, the elastic webs 24,25 extend all the way to the
leg opening cut-outs 45 so that the front and back panels of the
finished absorbent garment 21 extend all the way to the leg
openings. Similarly, the elastic webs 24,25 may extend all the way
to into the elastic waist bands 61 and even be folded together with
the continuous base web 23 in the waist bands 61. However, there is
preferably a gap between the elastic webs 24,25 in the crotch panel
58. This means that the edges of the elastic webs 24,25 that are
farthest away from the edges 8,9 of the production web are located
at distance from each other. The crotch panel 58 is located in a
part of the absorbent article that will normally be generally
non-elastic due to the absorbent core being non-elastic.
[0103] The process according to the invention may in a conventional
manner include the application of further elements such as
elasticised or non-elasticised barriers, lotion, odour control
agents, shaping elements, stabilising elements, etc.
[0104] Particularly, the process may include treating the
continuous base web 23 so that it is provided with areas of
different hydrophilicity or hydrophobicity. Hydrophobic polymeric
materials are commonly used in topsheets for absorbent articles. In
order to improve liquid permeability, the materials are treated
with surfactants or by modification of the surface of the materials
to render them more hydrophilic. Preferably, a portion of the
continuous base web that covers the absorbent cores is treated to
render it more hydrophilic or less hydrophobic than portions of the
base web 23 that are located outside of the absorbent cores.
Accordingly, the more hydrophobic portions of the base web may be
used to form the elastic waist band and those parts of the back and
front panels that are not coincident with the cores. A simple way
of accomplishing differential hydrophilicity in the continuous base
web 23 is to treat an area of the base web 23 extending in the MD
and having a width that is equal to the length of the absorbent
cores. Alternatively, the treatment may be carried out
intermittently, so that the parts of the continuous base web 23
located between the absorbent cores in the MD are left
untreated.
[0105] It is alternatively possible to use a hydrophilic base web
23 and treat the portions that should be less hydrophilic or more
hydrophobic with a hydrophobicity enhancing agent.
[0106] The pant diaper 55 shown in FIGS. 5 and 6 is designed to
enclose the lower part of a wearer's trunk in the manner of
conventional underwear. In FIG. 5, the diaper 55 is shown from the
inside, i.e. from the side facing the wearer when the garment is
worn and in FIG. 6, the diaper is shown from the outside, or the
garment-facing side, which is the side that is facing away from the
wearer when the diaper is worn. In FIG. 5 the diaper is shown in a
flat state with all elastic elements in a stretched-out state and
in FIG. 6 the diaper is shown as it appears when it is worn, with
partially contracted elastic elements and with closed side
seams.
[0107] The diaper has a front panel 56, a back panel 57 and a
crotch panel 58 extending between the front and back panels 56,57
and having a relatively narrow width as compared to the front and
back panels 56,57. The front and back panels 56,57 are arranged to
cover the wearer's hips and to extend over the belly and the back
of the wearer to encircle the lower part of the wearer's trunk.
[0108] The diaper 55 further comprises a core region 59 extending
from the crotch panel 58 into the front panel 56 and the back panel
57. The front and back panels 56,57 form part of a diaper chassis.
The chassis 60 comprises the front panel 56, the back panel 57 the
crotch panel 58 and an elastic waist band 61 arranged at the front
and back panels 56,57. Each of the front and back panels 56,57 has
a waist edge 62 a crotch edge 63 and a pair of side edges 64.
[0109] The term "panel" is used herein to denote a delimited part
of the diaper chassis having defined boundaries while the terms
"region" and "portion" are used to denote a more approximate
location of a particular feature of the diaper in the chassis or to
describe the intended positioning of a particular part of the
diaper in relation to a user's body. A panel may be formed from
separate materials or may be completely or partially formed from
materials that also extend into one or more contiguous panels. A
region or portion may have an extension fully or partially covering
one or more panels. The chassis is defined as the part of the
pant-type absorbent garment supporting the absorbent component and
comprises inner and outer covering layers, elastic elements,
etc.
[0110] When components are joined, attached or secured to each
other, they are originally separate parts that have been bonded by
any suitable means such as adhesively, by stitching or by
ultrasonic welding or thermo-welding. The term joined is also
intended to include separable (openable) joins, such as separable
side joins and reclosable joins such as hook-and loop joins,
reclosable tape joins, snap fasteners, etc. Components that have
been arranged on each other need not be bonded, although as used
herein, the term "arranged" is intended to also include bonded
configurations.
[0111] The front and back panels 56,57 have been joined to each
other along their side edges 64 by thermobonding, ultrasonic
welding, glue strings or the like to form side seams 65, as shown
in FIG. 6. The elastic waist band 61 consists of a front waist
panel 61a and a back waist panel 61b, extending from the front
panel 56 and the back panel 57, respectively. The front and back
waist panels 61a, 61b are also joined to each other along the side
seams 65. By joining the front and back panels 56, 57 and the waist
panels 61a, 61b, along the side seams 65, the pant diaper 55 is
provided with a waist opening 66 and a pair of leg openings 67.
[0112] FIG. 5 shows the diaper 55 in a flat state with any elastic
components that are attached to the chassis 60 under tensional
stress drawn out to the fully extended dimensions of the chassis
60. FIG. 6 shows the pant diaper 55 as it appears when the side
seams 65 have been formed and the tensioned elastic elements have
been allowed to relax and gather the chassis material to form
elasticized leg openings 67 and an elasticized waist opening
66.
[0113] In accordance with the invention, the front and back panels
56,57 include an elastic material 68 that has been laminated to a
non-elastic nonwoven layer arranged on the inside of the diaper.
The front and back panels 56,57 are preferably elastically
stretchable at least in the direction of the waist edges 62 but may
also be elastically stretchable perpendicular to the waist edges
62, in the direction of the side edges 64. The elastic material 68
and the front and back panels 56,57 extend from the waist edges 62
all the way to the leg openings 67.
[0114] The crotch panel 58 is the part of the chassis that is
located between the front and back panels 56, 57 in the
longitudinal direction of the diaper 55. The crotch panel comprises
a nonwoven crotch material 69 that has been joined to the front and
back panels 56,57 at crotch seams 70. Hence, the crotch material 69
which is a non-elastic material, such as a non-elastic nonwoven
material overlaps slightly with the elastic front and back panels
56,57. The crotch material 69 is joined along its transverse edges
71,72 to the front and back panels 56,57 at the overlapping
portions. The joining can be made in any suitable way such as by
ultrasonic welding, adhesively or similar.
[0115] The planar extension of the core region 59 is defined by a
liquid-impervious barrier sheet 76 arranged between an absorbent
core 77 and the chassis 60. The liquid-impervious barrier sheet 76
is shown to have a rectangular shape and the absorbent core 77 is
hour-glass shaped. However, both the barrier sheet 76 and the
absorbent core 77 may have alternative shapes.
[0116] As an alternative to the embodiment shown in FIGS. 5 and 6,
it is possible to dispense with the nonwoven crotch material. In
such an embodiment, the liquid-impervious barrier sheet 76 forms
the crotch panel of the chassis.
[0117] A liquid permeable topsheet 78 is arranged over the core 77
and the liquid-impervious barrier sheet 76. The topsheet 78 forms a
continuous inner surface of the diaper chassis 60 and consists of a
layer of nonwoven material or a liquid permeable laminate
comprising a nonwoven layer. As previously discussed, in
embodiments where the elastic webs 24,25 are bonded to the inner
surface of the continuous liquid permeable layer, the inner surface
of the diaper chassis 60 comprises the elastic webs 24,25 arranged
in the front and back panels 56,57.
[0118] The liquid-impervious barrier sheet 76 can consist of a
liquid-impermeable plastic film, a nonwoven sheet which has been
coated with a liquid barrier material, or some other flexible
material sheet which has the ability to withstand liquid
penetration. However, it can be advantageous if the
liquid-impervious barrier sheet 76 is breathable, i.e. permits the
passage of water vapour through the sheet 76.
[0119] The absorption core 77 comprises absorbent material, such as
cellulose fluff pulp, tissue, absorbent foam, etc. It is also
possible for the absorption core to contain superabsorbents, i.e.
polymer materials which are able to absorb body fluid corresponding
to many times their own weight and form a hydrogel. Superabsorbents
are usually provided in the form of particles, but fibres, flakes,
granules and films are also available. Moreover, the absorption
core 77 can comprise non-absorbent components such as stiffening
elements, shaping elements, binders, etc. Various types of
liquid-receiving porous structures such as fibre wads, open-cell
foam or the like can also be included in the core.
[0120] The absorption core 77 may be produced separately and
included in a core component 32 that is subsequently integrated in
the diaper chassis as shown in FIGS. 1 and 2. The various
components included in the core component can be connected to one
another in a conventional manner, for example by adhesive bonding,
ultrasonic welding or thermowelding. The core component comprises
at least an absorbent core having a barrier layer applied as a
carrier layer on one surface of the core. Preferably, a liquid
permeable layer such as a liquid acquisition layer is applied to
the opposite side of the core. Further components such as elastic
members, shape-stabilizing members, shaping elements or the like
may also be included.
[0121] In the diaper shown in FIGS. 5 and 6, the elastic waist band
61 is formed from extensions of the continuous inner nonwoven
topsheet material at the waist edges 62. The nonwoven material has
been elasticized by one or more elongate elastic members 73, such
as elastic threads or bands. The elastic members 73 have been
attached to an edge portion of the nonwoven topsheet 78 material
whereafter the topsheet material has been folded to cover the
elastic members 73 and has been secured in the folded configuration
in a waist band join 74. The elastic members 73 may be secured on
the side of the nonwoven topsheet material 78 that forms the inner
surface of the diaper 55 or on the opposite side. Preferably, the
elastic members 73 are arranged on the surface that is opposite to
the inner surface of the diaper so that the folded-over portion of
the nonwoven material if folded towards the outside of the diaper
55 leaving a smooth, continuous surface without any seams or edges
on the inside of the diaper. It is alternatively possible to attach
elastic elements to an edge portion of the topsheet material 78 and
leave the elastic elements non-covered, or covered by a separate
web. Further, the elastic waist band 61 may incorporate portions of
the elastic webs arranged at the front and back panels 55,66. The
elastic webs may be folded to create an edge portion having higher
elastic retraction force than a single-layer elastic web. The
folded elastic web may be supplemented by additional elastic
elements, if desired.
[0122] The elastic members 73 are arranged in the waist band 61 in
a tensioned state such that they contract and gather the nonwoven
material in the waist band 61 when they are allowed to relax, as
shown in FIG. 6.
[0123] In an alternative, less preferred embodiment, the elastic
waist band 61 can be a component that is prefabricated and joined
to the outside or the inside of the front and back panels 56,57
respectively. The waist band join 74 between the waist band 61 and
the front and back panels 56,57 can be made in any suitable way
such as by means of ultrasonic welding, heat welding, or
adhesively.
[0124] Elastic members 75 are also arranged along the edges of the
leg openings 67 and form leg elastic. The elastic members 75 at the
leg openings can be any kind of conventional elastic elements such
as elastic threads, bands, foam strips, or similar.
[0125] The core region 59 extends into the front and back panels
56,57 so that the elastic web 68 in these panels overlap with the
liquid-impervious barrier sheet 76 in the outer parts of the core
region 59 as seen in FIG. 5. The elastic web 68 is arranged on the
garment-facing side of the liquid-impervious barrier sheet 76.
[0126] The continuous inner nonwoven topsheet material has
preferably been treated so that the portions of the material
covering the absorbent core are more hydrophilic than portions of
the topsheet material being located outside the intended
fluid-receiving area of the article.
[0127] The elastic web 68 in the front and back panels 56,57
preferably comprises a nonwoven web that is arranged on the outside
of the diaper to create a textile outer garment-facing surface of
the diaper. Alternatively, the elastic web may consist of or
include an elastic film that forms an outer surface of the
diaper.
Elasticity Test
[0128] The method measures how an elastic material behaves at
cycles of repeated load and unload. The sample is stretched to a
predetermined elongation and a cyclic movement between 0 and said
predetermined elongation is performed. Desired load and unload
forces are recorded. The permanent, i.e. remaining, elongation of
the relaxed material is measured.
[0129] A tensile tester, Lloyd LRX, able to perform cyclic
movements and equipped with a printer/plotter or software
presentation is used. The sample is prepared by cutting it to a
width of 25 mm and a length that is preferably 20 mm longer than
the distance between the clamps in the tensile tester.
[0130] The tensile tester is calibrated according to the apparatus
instructions. The parameters needed for the test (load and unload
forces) are adjusted to:
TABLE-US-00001 Crosshead speed: 500 mm/min Clamp distance: 50 mm
Preload: 0.05 N
[0131] The sample is placed in the clamps according to the marks
and it is made sure that the sample I centred and fastened
perpendicularly in the clamps. The tensile tester is started and
three cycles between 0 and the predetermined elongation equal to
the highest defined 1.sup.st load are performed. Before the last
cycle, the sample is relaxed for 1 minute, then the permanent
elongation is measured by stretching the sample until a force of
0.1 N is detected and the elongation is read.
[0132] An elastic material is defined as a material having a
permanent elongation after relaxation of less than 10% after the
material has been subjected to an elongation of 30% in the test
above. An elongation of 30% means an elongation to a length that is
30% longer than the initial length of the sample.
[0133] A non-elastic material has a permanent elongation after
relaxation of more than 10% after having been subjected to an
elongation of 30%.
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