U.S. patent application number 13/774240 was filed with the patent office on 2013-06-27 for pant-type absorbent article.
This patent application is currently assigned to SCA Hygiene Products AB. The applicant listed for this patent is SCA Hygiene Products AB. Invention is credited to Margareta WENNERBACK.
Application Number | 20130165895 13/774240 |
Document ID | / |
Family ID | 36941427 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130165895 |
Kind Code |
A1 |
WENNERBACK; Margareta |
June 27, 2013 |
PANT-TYPE ABSORBENT ARTICLE
Abstract
A pant-type absorbent article having an absorbent assembly
having an absorbent core and a chassis, wherein the front and back
portions are joined to each other along two opposite longitudinal
side edges to define a waist-opening and a pair of leg-openings, at
least one of the front and back portions has an elastic web
material, a crotch portion located between the front portion and
the back portion in the longitudinal direction of the article, the
front portion having a length in the longitudinal direction, the
back portion having a length in the longitudinal direction, and the
crotch portion having a length in the longitudinal direction, the
absorbent assembly overlapping a distance with both the front and
back portions, the article having a longitudinal and a transverse
direction, wherein the absorbent assembly overlaps no more than 20%
of the surface area of each of the front and back portions.
Inventors: |
WENNERBACK; Margareta;
(Molnlycke, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCA Hygiene Products AB; |
Goteborg |
|
SE |
|
|
Assignee: |
SCA Hygiene Products AB
Goteborg
SE
|
Family ID: |
36941427 |
Appl. No.: |
13/774240 |
Filed: |
February 22, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12695580 |
Jan 28, 2010 |
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13774240 |
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11843419 |
Aug 22, 2007 |
7785307 |
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12695580 |
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PCT/SE2005/000307 |
Mar 2, 2005 |
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11843419 |
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Current U.S.
Class: |
604/385.29 ;
604/385.3 |
Current CPC
Class: |
A61F 13/15203 20130101;
A61F 13/496 20130101 |
Class at
Publication: |
604/385.29 ;
604/385.3 |
International
Class: |
A61F 13/49 20060101
A61F013/49 |
Claims
1. A pant-type absorbent article comprising a longitudinal
direction, a transverse direction, a longitudinal centerline, and
an absorbent assembly comprising an absorbent core and a chassis,
said chassis comprising a front portion and a back portion, wherein
the front and back portions are joined to each other along two
opposite longitudinal side edges to define a waist-opening and a
pair of leg-openings, at least one of the front and back portions
comprises an elastic web material, the elastic web material
extending continuously from one longitudinal side edge of the front
portion or the back portion, across the longitudinal centerline,
and to the other longitudinal side edge, said article further
comprising a crotch portion located between the front portion and
the back portion in the longitudinal direction of the article, said
front portion having a length (b1) in the longitudinal direction,
said back portion having a length (b3) in the longitudinal
direction, and said crotch portion having a length (b2) in the
longitudinal direction, said absorbent assembly lying at least in
said crotch portion and overlapping a certain distance with both
the front and back portions, said article having a waist elastic
member on each of the front portion and the back portion and
extending from one longitudinal side edge of the front portion and
the back portion, respectively, across the longitudinal centerline,
and to the other longitudinal side edge of the front portion and
the back portion, respectively, and said article having a maximum
width (c) in the transverse direction and a maximum length (b) in
the longitudinal direction, wherein a ratio of the maximum width
(c) to the maximum length (b) of the article is between 90% and
110% as measured in an extended state of the article.
2. The pant-type absorbent article according to claim 1, wherein
the length (b2) of the crotch portion is between 10-40% of the
entire length of the article (b) as measured in an extended state
of the article.
3. The pant-type absorbent article according to claim 1, wherein,
both of the front and back portions comprise said elastic web
material.
4. The pant-type absorbent article according to claim 3, wherein
the crotch portion is substantially free from said elastic web
material and the length (b2) of the crotch portion is substantially
equal to the distance between panels of the elastic web material in
the front and back portion.
5. The pant-type absorbent article according to claim 1, wherein
the absorbent assembly comprises a liquid impervious backsheet
layer, a liquid pervious topsheet layer and the absorbent core
enclosed therebetween.
6. The pant-type absorbent article according to claim 1, wherein
the crotch portion comprises a crotch panel material underlying the
absorbent assembly on the garment facing side thereof.
7. The pant-type absorbent article according to claim 6, wherein
the crotch panel material comprises substantially inelastic web
material.
8. The pant-type absorbent article according to claim 7, wherein
the inelastic web material is a nonwoven material.
9. The pant-type absorbent article according to claim 1, wherein
the elastic web material is a laminate composed of first and second
layers of fibrous material and an elastic film layer located
between said first and second fibrous layers.
10. The pant-type absorbent article according to claim 9, wherein
said elastic layer is a film layer that is breathable.
11. The pant-type absorbent article according to claim 10, wherein
said elastic laminate has a Water Vapour Transmission Rate
according to ASTM E96-00 Procedure D of at least 1500 g/m2 24
h.
12. The pant-type absorbent article as claimed in claim 9, wherein
said laminate elastic web material comprises first and second
fibrous layers of spunbond material, each having a basis weight of
between 10 and 35 g/m2 and the elastic layer is a breathable
elastic film layer having a basis weight between 20 and 80 g/m2,
said elastic laminate having a Water Vapour Transmission Rate
according to ASTM E96-00 Procedure D of at least 1500 g/m2 24
h.
13. The pant-type absorbent article according to claim 1, wherein
the elastic web material has a basis weight of no more than 100
g/m2.
14. The pant-type absorbent article according to claim 1, wherein
said elastic web material has an elasticity in the transverse
direction of the article of at least 30%, when measured according
to the elasticity test specified in the description.
15. The pant-type absorbent article according to claim 1, wherein
the elastic web material has an elasticity in the longitudinal
direction of the article of at least 20% when measured according to
the elasticity test specified in the description.
16. The pant-type absorbent article according to claim 1, wherein
the absorbent assembly overlaps more than 0% and no more than 20%
of the surface area of each of the front and back portions, so that
the absorbent assembly overlaps more than 0% and no more than 20%
of the surface area of the elastic layer, as measured in an
extended state of the article.
17. The pant-type absorbent article according to claim 1, wherein
the length (b2) of the crotch portion is between 25-35% of the
entire length of the article (b) as measured in an extended state
of the article.
18. The pant-type absorbent article according to claim 1, wherein
the pant-type absorbent article comprises a longitudinal
centerline, and the elastic web material extends continuously from
one longitudinal side edge of the front portion or the back
portion, across the longitudinal centerline, and to the other
longitudinal side edge.
19. The pant-type absorbent article according to claim 1, wherein
the entirety of at least one of the front and back portions
comprises an elastic web material.
20. The pant-type absorbent article according to claim 1, wherein
substantially all of at least one of the front and back portions is
formed of an elastic web material that comprises an elastic layer
located between first and second fibrous layers such that the
elastic web material exhibits at least 30% elasticity in the
transverse direction, and the article further comprises a leg
elastic.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 12/695,580, filed on Jan. 28, 2010 which is a
divisional of U.S. patent application Ser. No. 11/843,419, filed on
Aug. 22, 2007, which is a continuation of International Application
No. PCT/SE2005/000307, filed on Mar. 2, 2005, and which designates
the U.S. The entire contents of the prior applications are
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention refers to a pant-type absorbent
article such as a pant diaper, a sanitary pant or incontinence
garment, said article comprising an elastic web material.
BACKGROUND
[0003] Absorbent articles having defined core regions and chassis
regions are supposed to have a comfortable fit about the wearer.
For pant articles like pant diapers, sanitary pants and
incontinence pants it is also desirable that the articles are
capable of being pulled up and down over the hips of the wearer to
allow the wearer or caregiver to easily put on and remove the
article when it has been soiled. It is known to make such absorbent
pants with elasticized stretchable side portions and waist portion,
usually comprising elastic members, such as elastic threads,
contractably affixed between the backsheet and the topsheet.
[0004] It is further known to make portions of the chassis of
absorbent articles of an elastic material, such as stretch-bonded
laminates. Such laminates may include a layer of meltblown
elastomeric fibers which have been stretched and sandwiched between
outer layers of spunbonded webs.
[0005] U.S. Pat. No. 6,552,245 discloses an extensible outer cover
for an absorbent article which provides a certain permanent
deformation when subjected to a tensile force. The extensible outer
cover comprises a necked laminate in the form of one layer of a
necked non-elastic film and one layer of an elastic film. The films
may be breathable.
[0006] WO 03/047488 discloses an elastic laminate comprising an
elastic film which on opposite sides is bonded to first and second
non-elastic fibrous layers. The laminate is made by bonding the
non-elastic fibrous layers to the elastic film layer and
subsequently stretching the composite material, causing the
non-elastic materials to break. The elastic film material may be of
a breathable material. The laminate may be incorporated in an
absorbent article.
[0007] US 2004/0243086 discloses a disposable pant-like
undergarment having stretchable front and back portions, for
example made of an elastic laminate. An absorbent assembly is
secured to the front and back portions.
[0008] Further examples of absorbent articles which in part are
made of elastic laminates are found in U.S. Pat. No. 6,476,289 and
JP 10043235.
[0009] International applications PCT/SE2004/001004,
PCT/SE2004/001005 and PCT/SE2004/001415 refer to absorbent articles
comprising an outer coversheet in the form of an elastic laminate
having improved properties such as cloth-like feel and
appearance.
[0010] To obtain good fit, improved comfort and security against
leakage, it is important that absorbent articles have dimensions
which match the relative dimensions of the wearer. The relative
dimensions of the article are also important, so that the
components or regions of the article are not excessively large or
small relative to each other. The overall dimensions of the article
and relative dimensions of its components may also be adjusted so
as to obtain an article with a more pant-like appearance. Elastic
materials may be used to improve fit, but these are often
expensive, so a need exists for articles which are elastic in those
parts where elasticity is important, yet may comprise (cheaper)
inelastic material in those parts where elasticity is less
important. The correct choice of elastic and inelastic materials
must be made for the different components or regions of the
article, thus balancing the interests of economy and good fit of
the article.
[0011] Furthermore, the elastic properties of the elastic web
materials used in the construction of the article must be preserved
wherever possible.
[0012] There is still need for improvement of the properties of
absorbent articles comprising an elastic web material, such as an
elastic laminate, particularly their fit and appearance. The
comfort and soft feel of absorbent articles of the above-mentioned
type is also important. Furthermore, improvements in manufacturing
methods allow manufacturing costs to be kept to a minimum, which is
important for disposable articles, as they are discarded after a
single use.
OBJECT AND SUMMARY
[0013] An object of the present disclosure is to provide a
pant-type absorbent article which avoids the problems associated
with known articles of this type. This is achieved by a pant-type
absorbent article (such as a pant diaper, a sanitary pant or
incontinence pant) said article having an absorbent assembly
comprising an absorbent core, and a chassis. The chassis comprises
a front portion and a back portion, which are joined to each other
along two opposite longitudinal side edges to define a
waist-opening and a pair of leg-openings. At least one of the front
and back portions comprises an elastic web material. The article
further comprises a crotch portion located between the front
portion and the back portion in the longitudinal direction of the
article. The front portion has a length (b1) in the longitudinal
direction, the back portion has a length (b3) in the longitudinal
direction, and the crotch portion has a length (b2) in the
longitudinal direction. The absorbent assembly lies at least in
said crotch portion and overlaps a certain distance with both the
front and back portions, and the article has a longitudinal (y) and
a transverse direction (x).
[0014] According to one embodiment of the disclosure, the absorbent
assembly overlaps no more than 20%, preferably no more than 10%, of
the surface area of each of the front and back portions, as
measured in an extended state of the article. The term "extended
state" will be described more fully below.
[0015] In this way, the pant-type absorbent article provides good
fit, improved comfort and security against leakage, as the article
adapts to the shape of the wearer's body more easily. Using a
combination of portions in particular parts of the article allows
specification of the components more easily, and selection of those
which are most suitable in a given portion.
[0016] In another embodiment of the disclosure, the article has a
front half defined by the edges of the article and a transverse
centre line of the article, and a rear half defined by the edges of
the article and a transverse centre line of the article. The
surface area of the front half is between 80% and 90% of the
surface area of the rear half, as measured in an extended state of
the article.
[0017] In a further embodiment, the article has a maximum width (c)
in the transverse direction and a maximum length (b) in the
longitudinal direction. The ratio of the maximum width (c) to the
maximum length (b) of the article is between 80% and 120%,
preferably between 90% and 110%, as measured in an extended state
of the article. Furthermore, the ratio of the length (b1) of the
front portion to the width (c) of the article may be between 25%
and 35%, preferably between 28 and 32%, as measured in an extended
state of the article. The ratio of the length (b3) of the back
portion to the width (c) of the article may be between 38% and 52%,
as measured in an extended state of the article.
[0018] The length (b2) of the crotch portion is between 10-40%,
preferably between 20-40%, most preferably between 25-35% of the
entire length of the article (b) as measured in an extended state
of the article.
[0019] In one embodiment both of the front and back portions
comprise said elastic web material.
[0020] According to one aspect of the disclosure the crotch portion
is substantially free from said elastic web material and that the
length of the crotch portion is substantially equal to the distance
between panels of the elastic web material in the front and back
portion.
[0021] Preferably, the absorbent assembly comprises a liquid
impervious backsheet layer, a liquid pervious topsheet layer and an
absorbent core enclosed therebetween.
[0022] In one embodiment, the crotch portion comprises crotch panel
material, which is preferably a substantially inelastic web
material, and which underlies the absorbent assembly on the
garment-facing side thereof. Preferably, the inelastic web material
is a nonwoven material.
[0023] According to one embodiment, the elastic web material is a
laminate composed of first and second layers of fibrous material
and an elastic film layer located between said first and second
fibrous layers. In a further embodiment, the elastic film layer is
breathable.
[0024] In one aspect of the disclosure the elastic laminate has a
Water Vapour Transmission Rate according to ASTM E96-00 Procedure D
of at least 1500 g/m.sup.2 24 h, preferably at least 3000 g/m.sup.2
24 h.
[0025] According to one embodiment, said elastic laminate comprises
first and second fibrous layers of spunbond material, each having a
basis weight of between 10 and 35 g/m.sup.2, preferably between 12
and 30 g/m.sup.2, more preferably between 10 and 25 g/m.sup.2, and
a breathable elastic film layer having a basis weight between 20
and 80 g/m.sup.2, preferably between 20 and 60 g/m.sup.2, said
elastic laminate having a Water Vapour Transmission Rate according
to ASTM E96-00 Procedure D of at least 1500 g/m.sup.2 24 h,
preferably at least 3000 g/m.sup.2 24 h.
[0026] According to a further embodiment, said elastic web material
has an elasticity in the transverse direction of the article of at
least 30%, preferably at least 50%, more preferably at least 70%,
when measured according to the elasticity test specified
herein.
[0027] In one aspect of the disclosure the elastic web material has
a basis weight of no more than 100 g/m.sup.2, preferably no more
than 90 g/m.sup.2.
BRIEF DESCRIPTION OF DRAWINGS
[0028] Embodiments of the invention will be described in the
following in greater detail by way of example and with reference to
the accompanying drawings, in which:
[0029] FIG. 1 shows a perspective view of a pant diaper according
to an embodiment of the present invention.
[0030] FIG. 2 shows is a plan view of the pant diaper in its flat,
fully-extended state prior to formation as seen from the
body-facing side.
[0031] FIG. 3 is a corresponding plan view from the opposite,
garment-facing side of the pant diaper.
[0032] FIG. 4 is a cross section according to the line VI-VI in
FIG. 3.
[0033] FIG. 5 is a cross section through an elastic laminate
according to the line VII-VII in FIG. 3.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0034] Absorbent article
[0035] The term "absorbent article" refers to products that are
placed against the skin of the wearer to absorb and contain body
exudates, like urine, faeces and menstrual fluid. The invention
mainly refers to disposable absorbent articles, which means
articles that are not intended to be laundered or otherwise
restored or reused as an absorbent article after use. The invention
refers to "pant-type absorbent articles", having a core region and
a chassis region surrounding the core region. Examples of such
pant-type absorbent articles are pant diapers, sanitary pants and
incontinence pants.
[0036] The drawings show an embodiment of a pant diaper 1 for an
infant or an incontinent adult. Said pant diaper typically
comprises an absorbent core 2 located in the absorbent assembly 3
of the article. The diaper further comprises a chassis 4. The
chassis comprises a front portion 5, a back portion 6. The article
may comprise an elastic waist band 17.
[0037] The article has a longitudinal direction y and a transverse
direction x. The absorbent assembly 3 comprises a liquid pervious
topsheet 20 and a liquid impervious backsheet 19. The absorbent
core 2 is enclosed between the topsheet 20 and the backsheet 19
(FIG. 4).
[0038] Topsheet
[0039] The liquid pervious topsheet 20 can consist of a nonwoven
material, e g spunbond, meltblown, carded, hydroentangled, wetlaid
etc. Suitable nonwoven materials can be composed of natural fibers,
such as woodpulp or cotton fibres, manmade fibres, such as
polyester, polyethylene, polypropylene, viscose etc. or from a
mixture of natural and manmade fibres. The topsheet material may
further be composed of tow fibres, which may be bonded to each
other in a bonding pattern, as e.g. disclosed in EP-A-1 035 818.
Further examples of topsheet materials are porous foams, apertured
plastic films etc. The materials suited as topsheet materials
should be soft and non-irritating to the skin and intended to be
readily penetrated by body fluid, e.g. urine or menstrual fluid.
The topsheet may be different in different parts of the absorbent
article.
[0040] Backsheet
[0041] The liquid impervious backsheet 19 comprised in the
absorbent assembly 3 on the garment-facing side of the absorbent
core 2 is of a liquid impervious material, such as a thin plastic
film, e.g. a polyethylene or polypropylene film, a nonwoven
material coated with a liquid impervious material, a hydrophobic
nonwoven material which resists liquid penetration or a laminate
comprising plastic films and nonwoven materials. The backsheet 19
may be breathable so as to allow vapour to escape from the
absorbent core, while still preventing liquids from passing
therethrough. Examples of breathable backsheet materials are porous
polymeric films, nonwoven laminates from spunbond and meltblown
layers, laminates from porous polymeric films and nonwovens. The
backsheet 9 is preferably inelastic.
[0042] Elastic web material
[0043] At least one of the front and back portions 5 and 6 of the
chassis 4 comprises an elastic web material 10. Preferably both
portions 5 and 6 comprise elastic web material 10. The elasticity
in the x-direction of the elastic web material 10 should be at
least 30%, preferably at least 50%, more preferably at least 70%,
as measured by the elasticity test specified herein.
[0044] Preferably the elastic web material 10 is also elastic in
the y-direction of the article. However the elasticity in the
y-direction is preferably lower than in the x-direction. The
elasticity in the y-direction should be at least 20%.
[0045] In the embodiment shown and described herein, the elastic
web material is an elastic laminate 10 composed of first and second
outer layers of fibrous material 11 and 12 and a middle elastic
film layer 13 located between said fibrous layers (see FIG. 5).
However it is understood that other types of elastic web materials
may be used, such as elastic nonwoven materials, nonwoven materials
which are per se inelastic, but which have been elastified by means
of elastic threads etc. The elastic web materials may comprise one
layer or two or more layers that have been laminated.
[0046] In the elastic laminate shown and described herein, it is
preferred that the outer fibrous layers 11 and 12 are chosen so
that they, in combination with the inner elastic film layer 13,
give the material high resistance to puncture. They also provide a
soft and cloth-like feel to the laminate. Examples of suitable
materials are carded webs and spunbond materials. The basis weight
of the fibrous material layers should be between 10 and 35
g/m.sup.2, preferably between 12 and 30 g/m.sup.2, more preferably
between 15 and 25 g/m.sup.2. Examples of suitable polymers used in
the fibrous materials are polyethylene, polyesters, polypropylene
and other polyolefin homopolymers and copolymers. Natural fibres,
for example cotton, may also be used as long as they provide the
required properties. A mixture of polymers can contribute to a
higher flexibility of the nonwoven layer, and through this, give
the nonwoven material a higher elongation at maximum load. A
mixture of polyethylene and polypropylene polymers has proved to
provide good results in this respect. A mixture of fibers of
different polymers is also possible.
[0047] The middle layer 13 is according to one embodiment of the
invention an apertured elastic film having a basis weight between
20 and 80 g/m.sup.2, preferably between 20 and 60 g/m.sup.2. The
film may be of any suitable elastic polymer, natural or synthetic.
Some examples of suitable materials for the elastic film are low
crystallinity polyethylenes, metallocene-catalyzed low
crystallinity polyethylene, 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 film is an
apertured three-layer elastomeric film of PE-SEBS-PE.
[0048] The total basis weight of the laminate is preferably 100
g/m.sup.2 or less, more preferably no more than 90 g/m.sup.2.
[0049] The elastic laminate 10 may be manufactured according to the
method disclosed in WO 03/047488, wherein one spunbond layer 11 is
applied to the film 13 in a tacky state and will thus bond to the
film layer, while the other spunbond layer 12 is adhesively
laminated to the film layer 13, using for example a pressure
sensitive hot melt adhesive. Alternatively the laminate is
manufactured according to a modified version of this known method,
wherein the modification involves that the laminate is
incrementally stretched (through intermeshing gears, IMG), to a
point below the elongation at peak load of at least one of the
non-elastic nonwoven layers to retain some strength for at least
one of the nonwoven layers. The other layer may also be stretched
to a point below its elongation at peak load, or to a point at
which it will tear during stretching.
[0050] The method disclosed in WO 03/047488 involves stretching of
the laminate above the point of failure of the fibrous material, so
that the non-elastic layers break completely. Therefore, as
described in WO 03/047488, the elongation of the laminate is not
limited by the stretch modulus of the non-elastic material.
[0051] In a preferred embodiment at least one, preferably both
fibrous layers, which are bound to the elastic film, are (in
contrast to the method described in WO 03/047488) not completely
torn upon manufacture of a laminate according to the present
invention. Selection of fibrous materials which have an elongation
at maximum load greater than the elasticity of the elastic laminate
allows the elastic film to stretch without being hindered by the
fibrous layers. Such a selection also ensures that the fibrous
layers contribute to the puncture resistance of the laminate, as
they are not completely torn or broken during manufacture.
Preferably both fibrous layers or at least one of the fibrous
layers have an elongation at maximum load that is at least 10%
higher than the elasticity of the laminate. This is described in
more detail in PCT/SE2004/001005, which is incorporated herein by
reference.
[0052] The opacity of a material layer is the characteristic
ability of the material layer to visually hide from view an
underlying object or pattern. The opacity is measured in %, wherein
100% opacity means that nothing can be seen through the material
layer and 0% means that the material layer is completely
transparent. The opacity is measured by the Opacity Test described
below, which is based on luminous-reflectance-factor data.
[0053] Opacity of the laminate can be obtained by the incorporation
of opacifying fillers into the laminate, particularly into the
elastic film. Such pigments can be organic or inorganic dyes,
colouring agents, or whitening agents. Inorganic materials such as
titanium dioxide, inorganic carbonates, synthetic carbonates, talc,
nepheline syenite, magnesium hydroxide, aluminium trihydrate
siatomaceous earth, mica, natural or synthetic silicas, calcinated
clays and mixtures thereof are all examples of preferred opacifying
fillers.
[0054] The filler is preferably added as a master batch at the
extrusion of the film. One example of an appropriate concentration
is about 5% filler by weight of the film.
[0055] It is further preferred that the elastic laminate 10 has a
breathability (Water Vapour Transmission Rate) according to ASTM
E96-00 Procedure D of at least 1500 g/m.sup.2 24 h, preferably at
least 3000 g/m.sup.2 24 h.
[0056] The open area of the elastic film layer is preferably at
least 5%, more preferably at least 8%. The open area is measured by
image analysis methods and is defined as the sum of the hole area
divided by the total area of the film sample.
[0057] Absorbent core
[0058] The "absorbent core" is the absorbent structure disposed in
the absorbent assembly of the absorbent article. The absorbent core
2 can be of any conventional kind. Examples of commonly occurring
absorbent materials are cellulosic fluff pulp, tissue layers,
highly absorbent polymers (so called superabsorbents), absorbent
foam materials, absorbent nonwoven materials or the like. It is
common to combine cellulosic fluff pulp with superabsorbent
polymers in an absorbent core. Superabsorbent polymers are
water-swellable, water-insoluble organic or inorganic materials
capable of absorbing at least about 20 times its weight and in an
aqueous solution containing 0.9 weight percent of sodium chloride.
Organic materials suitable for use as a superabsorbent material can
include natural materials such as polysaccharides, polypeptides and
the like, as well as synthetic materials such as synthetic hydrogel
polymers. Such hydrogel polymers include, for example, alkali metal
salts of polyacrylic acids, polyacrylamides, polyvinyl alcohol,
polyacrylates, polyacrylamides, polyvinyl pyridines, and the like.
Other suitable polymers include hydrolyzed acrylonitrile grafted
starch, acrylic acid grafted starch, and isobutylene maleic
anhydride copolymers and mixtures thereof. The hydrogel polymers
are preferably lightly crosslinked to render the material
substantially water insoluble. Preferred superabsorbent materials
are further surface crosslinked so that the outer surface or shell
of the superabsorbent particle, fiber, flake, sphere, etc.
possesses a higher crosslink density than the inner portion of the
superabsorbent. The superabsorbent materials may be in any form
suitable for use in absorbent composites including particles,
fibers, flakes, spheres, and the like.
[0059] A high absorption capacity is provided by the use of high
amounts of superabsorbent material. For an absorbent core
comprising a matrix of hydrophilic fibers, such as cellulosic
fibers, and superabsorbent material, the proportion of
superabsorbent material is preferably between 10 and 90% by weight,
more preferably between 30 and 70% by weight.
[0060] It is conventional in absorbent articles to have absorbent
cores comprising layers of different properties with respect to
liquid receiving capacity, liquid distribution capacity and storage
capacity. The thin absorbent bodies, which are common in for
example baby diapers and incontinence guards, often comprise a
compressed mixed or layered structure of cellulosic fluff pulp and
superabsorbent polymers. The size and absorbent capacity of the
absorbent core may be varied to be suited for different uses such
as for infants or for adult incontinent persons.
[0061] The absorbent core may further include an acquisition
distribution layer placed on top of the primary absorbent body and
which is adapted to quickly receive and temporarily store
discharged liquid before it is absorbed by the primary absorbent
core. Such acquisition distribution layers are well known in the
art and may be composed of porous fibrous waddings or foam
materials.
[0062] Pant diaper
[0063] The pant diaper disclosed in FIG. 1 is intended to enclose
the lower part of the wearer's trunk like a pair of underwear. It
comprises an absorbent assembly 3 and a chassis 4. The chassis 4
comprises a front portion 5 and a back portion 6. The front 5 and
back portions 6 are joined to each other along two opposite
longitudinal side edges by ultrasonic welds, glue strings or the
like to define a waist-opening and a pair of leg-openings of the
pant diaper.
[0064] At least one and preferably both of the front and back
portions 5,6 comprises an elastic web material 10 as described
above. The absorbent assembly 3 lies at least in said crotch
portion 7 and overlaps a certain distance with both the front and
back portions 5; 6, and the article has a longitudinal (y) and a
transverse direction (x).
[0065] The article 4 further comprises a crotch portion 7 located
between the front portion 5 and the back portion 6 in the
longitudinal direction of the article. The front portion 5 has a
length b1 in the longitudinal direction, the back portion 6 has a
length b3 in the longitudinal direction, and the crotch portion 7
has a length b2 in the longitudinal direction.
[0066] The article is thus divided into three portions (front
portion, crotch portion and back portion) in its longitudinal
direction, as shown in FIG. 2. The front portion is defined by the
waist edge of the article, the longitudinal side edges of the
article, part of the leg openings of the article and a transverse
line which is located at the point at which the angle of the edge
of the leg opening changes most abruptly (i.e. the point at which
the rate of change of the angle of the edge of the leg opening with
respect to the transverse direction is highest). The back portion
is defined in a similar manner: by the waist edge of the article,
the longitudinal side edges of the article, part of the leg
openings of the article and a transverse line which is located at
the point on the edge of the leg opening at which the angle of the
edge changes most abruptly (i.e. the point at which the rate of
change of the angle of the edge of the leg opening with respect to
the transverse direction is highest). The crotch portion is defined
on the longitudinal edges by the edges of the leg openings of the
article and on the transverse edges by the two transverse lines
described above.
[0067] It is important that the elastic web material of the
front/rear portions is allowed to flex and stretch when the article
is in use. If non-elastic layers are joined to this elastic web
material, its flexibility and extensibility is reduced. According
to embodiments of the invention, the absorbent assembly 3 overlaps
no more than 20%, preferably no more than 10%, of the surface area
of each of the front and back portions, as measured in an extended
state of the article.
[0068] The "extended state" of the article is herein defined as a
state in which the article has been extended in all four directions
to such an extent that all the elastic materials contained therein,
such as the elastic web material, the waist elastics, the leg
elastics, are extended to such an extent that they will not gather
any part of the product, but the entire products is completely
flat. The article is extended only to such an extent that this flat
condition is reached.
[0069] In another embodiment of the invention, the article has a
front half 14 defined by the edges of the article and a transverse
centre line 16 of the article, and a rear half 15 defined by the
edges of the article and a transverse centre line 16 of the
article. The surface area of the front half 14 is between 80% and
90% of the surface area of the rear half 15, as measured in an
extended state of the article. This provides a more pant-like shape
of the absorbent article.
[0070] In a further embodiment, the article has a maximum width (c)
in the transverse direction and a maximum length (b) in the
longitudinal direction, and the ratio of the maximum width (c) to
the maximum length (b) of the article is between 80% and 120%,
preferably between 90% and 110% as measured in an extended state of
the article. According to a preferred embodiment, the ratio of the
length (b1) of the front portion to the width (c) of the article
(b1/c) is between 25% and 35%, preferably between 28% and 32%, as
measured in an extended state of the article. Additionally, the
ratio of the length (b3) of the back portion to the width (c) of
the article (b3/c) is between 38% and 52%, as measured in an
extended state of the article. Articles conforming to these
measurements provide a more pant-like shape of the absorbent
article and a more secure fit.
[0071] To provide good fit and security against leakage, the length
(b2) of the crotch portion 7 should be between 10-40%, preferably
between 20-40%, most preferably between 25-35% of the entire length
of the article (b) as measured in an extended state of the
article.
[0072] The crotch portion 7 may comprise crotch panel material 21
which underlies the absorbent assembly on the garment-facing side
thereof.
[0073] According to one embodiment of the invention, the crotch
panel material 21 comprises substantially inelastic web material
18, although elastic materials may also be used. Suitably, the
inelastic web material 18 is a nonwoven material. The substantially
inelastic web material 18 is arranged in the crotch portion of the
article and may be joined to the elastic web material 10 at or
close to the borderline between the crotch portion 7 and the front
and back portions 5 and 6 respectively such that it is located
between these portions in a longitudinal direction of the article.
Although it may overlap with the front and back portions 5, 6
sufficiently to be joined to these portions, the inelastic web
material 18 does not significantly overlap with front or back
portions 5,6 over the majority of its surface.
[0074] In one embodiment of the invention both of the front and
back portions comprise the elastic web material 10, while the
crotch portion 7 is substantially free from the elastic web
material, wherein the length (b2) of the crotch portion 7 is
substantially equal to the distance between panels of the elastic
web material 10 in the front and back portions 5 and 6. However the
borderline between the front and back portions 5 and 6 and the
crotch portion 7 may or may not coincide with the joints between
the different panel materials 10 and 21. Thus joints between
different panel materials may extend over any of the front, back or
crotch portions.
[0075] The inelastic web material 18 of the crotch portion 7 may be
joined to the elastic web material 10 of the front and/or back
portions 5,6 while this is held in a selectively stretched
condition, so that gathers are present in the inelastic web
material 18 in the front and back crotch portion seams 8,9. The
gathers act to draw the pant-type absorbent article to the required
shape, thus providing a good fit, and also providing the article
with an appearance which is more pant-like.
[0076] In another embodiment, no separate crotch panel material 21
is provided, but the elastic web material 10 also underlies the
absorbent assembly 3 in the crotch portion of the article.
Alternatively, the absorbent assembly 3 alone bridges the front and
back portions 5 and 6.
[0077] The absorbent assembly 3 according to an embodiment of the
invention comprises a liquid impervious backsheet layer 19, a
liquid pervious topsheet layer 20 and an absorbent core 2 enclosed
therebetween, all of which components are described above. The
absorbent assembly 3 may be joined to the elastic web material 10
of the front and/or back portions 5, 6 while this is held in a
selectively stretched condition, so that gathers are present in the
absorbent assembly 3 at those points where it is joined to the
front and back portions 5, 6.
[0078] The pant-type absorbent article according to an embodiment
of the invention may comprise an elastic waist band 17 comprising
elastic members secured to the front and back portion. In an
alternative embodiment only one of the front 5 and back portions 6
have an elastic waist band 17 secured thereto. The elastic waist
band portions 17 which are secured to the front portion 5 and the
back portion 6, respectively, may also be joined to each other
along said side seams.
[0079] No additional elasticized side portions joining the front
and back portions 5 and 6 are needed when using the elastic web
material 10. If desired, additional elasticized side portions may
of course be provided, especially in cases where the elastic web
material 10 is arranged only in parts of the front and/or back
portions.
[0080] As stated above the elastic web material 10 has an opacity
of at least 40%, preferably at least 50% and more preferably at
least 60%. The opacity of the elastic web material provides a
cloth-like appearance to the article, which is of particular
importance when the article is a pant diaper. Especially in this
case, where the elastic web material forms the sole component in
considerable surface area regions of the pant diaper, such as large
areas of the front and back portions, and the absorbent core covers
only relatively small areas, 30% or less, of the article, the
appearance of the elastic web material is of great importance for
the overall appearance of the article. Thus by making the elastic
web material opaque with an opacity of at least 40%, the pant
diaper will appear more cloth-like and more like "normal"
underwear, than if the elastic web material would have a higher
degree of transparency. The opacity is measured by the Opacity Test
disclosed in PCT/SE2004/001415.
[0081] It is further desired that the elastic web material has a
puncture resistance of at least 15N as measured according to ASTM
Designation D3763-02. Preferably, the elastic web material of the
present invention has a puncture resistance of at least 20N, and
more preferably at least 30N.
[0082] The elastic web material should preferably have a softness
according to Kawabata of at least 20, preferably at least 30 and
most preferably at least 40. It is further desired that it has a
formability according to Kawabata of no more than 50, preferably no
more than 30, more preferably no more than 20 and most preferably
no more than 10. It is also desired that the elastic web material
has a drapability according to Kawabata of no more than 40. The
softness, formability and drapability according to kawabata are
measured according to the test methods given in
PCT/SE2004/001004.
[0083] Elasticity test
[0084] The method measures how an elastic material behaves at
repeated load and unload cycles. 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.
[0085] 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.
[0086] The tensile tester is calibrated according to the apparatus
instructions. The parameters needed for the test (load and unload
forces) are adjusted to:
[0087] Crosshead speed: 500 mm/min Clamp distance: 50 mm Preload:
0.05 N
[0088] The sample is placed in the clamps according to the marks
and it is made sure that the sample is 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 1st load, are performed. Before the last cycle,
the sample is relaxed for 1 minute, and the permanent elongation is
measured by stretching the sample until a force of 0.1 N is
detected and the elongation is read.
[0089] The permanent elongation after relaxation should be less
than 10% and is measured by the method above. Thus an elasticity of
30% is defined as that the laminate should have a permanent
relaxation after elongation of less than 10% after being exerted to
an elongation of 30% in the tensile tester above. An elongation of
30% means an elongation to a length that is 30% longer than the
initial length of the sample.
[0090] Dimensions
[0091] Some embodiments of the inventive articles have the
following dimensions and relative dimensions:
TABLE-US-00001 Crotch portion Product Back Front Crotch length
width (c)/ portion portion portion (b2)/ product length (b3)/
length (b1)/ length product length product product (b2)/product
length Product (b); % width (c); % width (c); % width (c); % (b); %
1 92 47 29 24 26 2 92 50 32 18 20 3 108 39 30 31 29
Overlap of absorbent assembly on front/back portions
TABLE-US-00002 Product % Overlap, back % Overlap, back 1 15 5 2 12
12
[0092] It is understood that although the invention has been
described with reference to preferred embodiments, several
modifications are possible within the scope of the claims and
equivalents thereof. The invention therefore intends to cover any
variations or equivalents which are within known or customary
practice within the technical field to which it belongs.
* * * * *