Note: Descriptions are shown in the official language in which they were submitted.
21 59932
Absorbent Sanitary Article
This invention relates to an absorbent sanitary
article. It is particularly concerned with pantiliners,
and will be so described, though it has application to
other sanitary articles, for example sanitary napkins,
incontinence products, and so forth.
Pantiliners on the market tend to be less than ideal
in terms of the comfort with which they are worn. One
reason for this is that they tend to bunch as a result of
the movements of the user's body. Not only does this
result in the user experiencing discomfort, but it also
means that the pantiliner absorbs less fluid than it
would otherwise absorb, as a result of the pantiliner
being in inadequate contact with the user.
It is an object of an aspect of the present
invention to provide a pantiliner which overcomes, or at
least reduces, the above problems, and which is suitable
for use in absorbing light fluid flows which may occur
between menstrual periods. Such fluid flows include both
vaginal discharge and urine. The construction of the
pantiliner is to be such that it is able to move with the
panty in which it is held, acting, so to speak, as an
extension of the panty itself.
An aspect of this invention is as follows:
A multi-layer, fluid-absorbent sanitary article for
use with a panty garment having an interior crotch area,
the article having means of attachment to said crotch
area, the article being flexible, and elastic in at least
one direction, the elasticity being such that in said at
least one direction the loading force required to extend
a sample of an elastic material used in a layer of the
article 1 inch in width to 1250 of an initial length is
not more than 4008, and the residual stretch after the
sample has been stretched three times to 125° of its
initial length and relaxed after each stretch is not more
than 150 of its initial length.
21 5 99 3 2
The said loading force is preferably not more than
250g, more preferably not more than 150g, and still
more preferably not more than 100g, and is preferably
at least 60g. The pad set is preferably not more than
120, and preferably not more than 8o.
Preferably, the liner has a flexibility, as
measured according to ASTM Standard D 1388-64, of not
more than 5000 mg. cm, preferably not more than 3000
mg.cm, though the flexibility value is preferably at
least 500 mg.cm. The pantiliner preferably has a
thickness under a pressure of 20g/cm2, of less than
2mm, and more preferably in the range of from 0.5 to
1.6 mm.
The pantiliner of the invention will normally be
generally elongate in shape, preferably having the
hourglass shape which has now become widely accepted
for such articles. The pantiliner may have elasticity
in only one direction, in which case that direction is
preferably transverse to the length of the pantiliner,
4'i ~ ~ 1
2159932
3
or it may have elasticity in both the transverse and
longitudinal directions.
There have been proposals in the prior art for
pantiliners and catamenial articles which have elastic
properties, and in this connection attention is directed
to W093/01785, US Patent 4166464, US Patent 4389211,
EP-A-160517 and EP-A-450541. None, however, discloses
the combination of properties which is set out above and
which renders the article of the present invention so
particularly suitable for its intended purpose.
The pantiliner of the present invention is
preferably intended to absorb, in use, up to about 2g of
fluid. For this level of discharge it is normally
constructed to have an absorbent capacity of at least
about 4 to 5 ml. This over- capacity is provided to take
into account the fact that the fluid absorbed may all
remain in the central region of the pantiliner, with the
outer regions thereof remaining completely or
substantially dry. This is likely to occur given the low
flow rates and flow volumes which are involved.
The pantiliner according to the invention is made
as a multilayer structure, at least one of these layers
being fluid- absorbent. Each layer is adhered to the
layer or layers immediately adjacent thereto. It has
been found that since the article does not have to
handle large fluid volumes it is unnecessary for the
fluid-absorbent layer or layers to be completely
enclosed between a topsheet and a backsheet, a
215993
- 4
construction which is often conventionally adopted to
prevent fluid leaking from the absorbent material
through the edges thereof. In the case of the article of
the present invention, fluid almost never reaches those
edges, and it is therefore of no consequence if those
edges are exposed to the outside.
Accordingly, it is possible for the pantiliner of
the present invention to consist of a plurality of
layers of identical or substantially identical size and
shape positioned in alignment with one another. This is
shown in Figure 1 of the accompanying drawings, which is
an exploded isometric view, and in which there is shown
a topsheet layer 1, adhesive 2, an absorbent core 3,
adhesive 4, a backsheet 5, and adhesive 6. The nature
and purpose of the various layers is discussed further
below. The use of such a structure means that it is
possible to produce a plurality of pantiliners by
cutting them from overlaid sheets of the materials
required, without the alignment problems which exist
where a topsheet and a backsheet have to be arranged to
form an envelope completely enclosing an absorbent core.
In order to provide the pantiliner with the
necessary elastic properties, it is necessary in the
case of a multilayer article for at least one of the
layers to be elastic, though all the layers must be
stretchable. It is found that the article as a whole has
the necessary elastic properties even if some, but not
all, of the layers are stretchable but not elastic.
~i~993~
_ s
In a further aspect thereof, the invention provides
an elastic, fluid-absorbent liner for use with a panty
garment, the liner having means of attachment to the
interior of the garment in the crotch area thereof, the
liner comprising a plurality of layers joined in
face-to-face relationship with one another by means of
at least one adhesive connection, the said adhesive
connection or one of said adhesive connections, being
provided by an elastic adhesive, whereby to provide, at
least in part, the elasticity of the liner.
In another aspect, the invention provides a
fluid-absorbent liner for use with a panty garment,
which comprises a layer of absorbent material exposed to
the exterior on one face thereof, and joined in
face-to-face relationship on its opposite face, by means
of an adhesive connection, with a backsheet of water-
impermeable material.
In yet another aspect, the invention provides an
elastic, fluid-absorbent sanitary article for use with a
panty garment, the article having means of attachment to
the interior of the garment in the crotch area thereof,
the article comprising a plurality of layers joined in
face-to-face relationship with one another by means of
at least one adhesive connection, the said adhesive
connection or one of said adhesive connections, being
provided by an elastic adhesive, whereby to provide, at
least in part, the elasticity of the article.
- 6
In still another aspect the invention provides a
fluid- absorbent sanitary article for use with a panty
garment, which comprises a layer of absorbent material
exposed to the exterior on one face thereof, and joined
in face-to-face relationship on its opposite face, by
means of an adhesive connection, with a backsheet of
water-impermeable material.
The invention also provides a fluid-absorbing
sanitary article, wherein the layers thereof, and the
connections therebetween, are such as to render it
permeable to water vapour and other gases.
Additionally, the invention provides a
fluid-absorbing sanitary article for use with a cotton
panty garment, the article having means for removably
attaching it to the interior of the panty garment in the
crotch area thereof, wherein the stress- strain
characteristics of the said article correspond to a
substantial extent to those of the said crotch area.
The following Table 1 sets out the function of the
layers in a multilayer construction which consists
successively, as considered from the body side of the
user outwards, of six layers.
TABLE 1
1. Topsheet Dry feeling/skin
friendly
2. Topsheet-to core adhesive Material adhesion
3. Absorbent core Absorbency
219932
4. Core-to-backsheet adhesive Material
adhesion/optionally air & vapour permeability
5. Backsheet Liquid impermeability
/optionally air & vapour permeability
6. Backsheet-to-panty adhesive Intimate panty
bonding
A description will now be given of examples of
materials which can be used for the above layers. It
should be noted at this point, however, that
constructions are possible which use fewer layers, or
more layers, than those just recited, and the materials
mentioned below may be suitable for the layers of such
constructions.
Topsheet
For a topsheet which is stretchable but not
elastic, one suitable material is a perforated or
apertured film which has been ring-rolled to provide it
with a degree of extensibility. One suitable film is
described in US Patent 4463045, and suitable processes
for ring-rolling such a film are described in US Patents
4107364, 4834741, 5143679, 5156793 and 5167897. Ring-
rolling has the effect of producing corrugations in the
topsheet, and the ring-rolled topsheet has an axis of
stretching which is perpendicular to the direction of
the fold lines. The fold lines can all run in a single
direction (i.e. parallel to one another), or in more
21 5 99 3 2
8
than one direction (for example in two mutually
parallel directions), and the sheet correspondingly has
one or more axes along which it can be stretched.
Another possible material which can be ring-rolled
to produce a stretchable topsheet is that described in
EP-A-207904.
For a topsheet which is to be elastic rather than
just stretchable, one possible material which can be
used is that described in our copending Italian Patent
Application IT 1,268,105. Further details of that
material are given below in relation to Product 3.
Absorbent Core
For a core which is to be stretchable but not
elastic, one material which can be used is a
hydrophilic, stretchable non- woven material. One such
material is an apertured, spunlaced material having a
basis weight of 50 g/m2 and consisting of 70o rayon,
30o polyethylene terephthalate (PET).
Another stretchable, substantially non-elastic
material which can be used is a tissue paper consisting
of conventionally CD (cross direction) creped tissue.
For example, a wet laid tissue paper can be used that
has been mechanically CD creped and has a weight of
47g/m2. Such a creped tissue is available from
.,
°,~~ , ~.
.,
2159932
9
Aticarta, Rome, Italy. This material does have some
elasticity when dry. However, it loses this when wet,
and, furthermore the amount of elasticity is only
small. Accordingly, it is not suitable as the sole
elastic component in a construction according to the
invention, all the other components being non- elastic.
The construction must include at least one other
component which is significantly elastic, and which
retains that elasticity even when wet.
For an absorbent core which is elastic, various
materials can be used. One class of suitable cores
consists of cores which include materials which are
inherently elastic. For example, the core can be made
of a fluff mixed with a net of elastic hot melt
adhesive, or a spunlaced nonwoven with an undernet of
elastic hot melt. The term "net" refers to a 3-
dimensional structure made of interlocked fibres of
elastic hot melt adhesive mixed with cellulose fibres
during the formation of the core. The term "undernet"
refers to a situation where the elastic hot melt is
applied as a filament, e.g. in spiral pattern, on a
substrate such as a spunlaced nonwoven. Both types of
structures may be carried out with equipment known in
the art. Thus, "nets", of elastic hot melt fibres can
be made with melt blowing equipment, e.g. the Flexi-
MeltT"~ apparatus by Nordson Corporation, Georgia, USA,
and a "Spyro"T"~ type applicator such as the Nordson
Series 6000T"~ by Nordson Corporation may be used to make
"undernets".
_.
2159932
A second class of suitable cores consists of cores
which have been mechanically treated to make them
elastic. For example, the core can be a tissue which
has been creped in CD (cross direction) or MD (machine
direction), or an absorbing web in which a large number
of short slits have been formed.
Backsheet
This must be a hydrophobic material, since its
function is to prevent body fluids, which are largely
aqueous, reaching, and therefore soiling, the user's
clothes.
For a stretchable but non-elastic backsheet, one
material can be used is a hydrophobic, stretchable,
spun laced, non-woven material having a basis weight of
from about 30 to 40 g/m2, formed of polyethylene
terephthalate or polypropylene fibres. This material
is breathable, i.e. permeable to water vapour and other
gases.
For an elastic backsheet, one material which can
be used is an elastic film sold under the trade mark
EXX500 by Exxon Corporation. The material of this film
is formed from an elastomeric base composition
consisting of a styrene block copolymer. However, this
material is not breathable. Another material which can
be used for an elastic backsheet is a plastic film that
has been subjected to a process that provides it with
elastic-like properties without attaching elastic
strands to the film, and may
,....
21 5 99 3 2
m
for example comprise a formed film made in accordance
with US Patents 4342314 (Radel et al) and 4463045 (Ahr
et al).
Adhesive for topsheet/core and core/backsheet
These two adhesives may the same as one another,
though they may alternatively be different. A suitable
elastomeric adhesive, which is a hot melt adhesive, is
described in our copending Italian Application IT
1,268,104. Briefly, that application describes an
elastomeric hot melt adhesive composition comprising at
least one thermoplastic elastomer and at least one
tackifying resin, the thermoplastic elastomer(s) being
a styrene/butadiene/styrene (SBS) copolymer or a blend
of styrene/butadiene/styrene with
styrene/isoprene/styrene (SIS) in which SIS is present
in an amount equal to or less than 50o by weight of the
total block copolymer, the composition being
characterised in that:
(a) it is capable of bonding, when applied from the
molten state, plastic and/or cellulosic materials with
a 90° peel force not lower than 0.5 N/cm;
(b) it has a tensile strength retention after 50
cycles of at least 400;
(c) it has a viscosity of 120,000 cps or less at 180°C
and an applied shear of 80 sec-1.
21 5 99 3 2
12
To adhere the topsheet to the core, the adhesive
is applied in discrete areas only, so that the fluid
entering the pantiliner through the topsheet is able to
pass into the core. For example, the adhesive may be
applied in lines at a rate of 0.06g/linear m. Other
patterns in which the adhesive can be applied include
free-window coating (i.e. coating only part of the
surface, so as to leave at least one adhesive-free
zone, or window, spaced from the outer edge of the
topsheet and core), and full coating with a low enough
basis weight (maximum 15 g/mz) that liquid still gets
through to the core.
To adhere the core to the backsheet, a continuous
layer of adhesive may be applied if desired, for
example at a rate of 20g/m2, though it may be applied
only in discrete areas, if that is preferred, for
example for reasons of economy.
Backsheet-to-panty adhesive
An adhesive used for this purpose is referred to
for short as a PFA (panty fastening adhesive). One
suitable PFA is that supplied under the trade name
SAVARE LA 203 by Savare of Milan, Italy. This adhesive
is based on an SEBS (styrene-ethylene- butylene-
styrene) copolymer and has a softening point of 65°C
according to the method of ASTM E28-67.
The PFA is preferably applied in a pattern as
defined in our copending Italian Patent Application
1 ii'...
13 21 5 99 3 2
IT 1,268,620. Briefly, those applications describe
adhesive patterns in which the adhesive is applied to
at least one surface region adjacent the periphery of
the article, and patterns in which the adhesive is
stretchable and may be applied over the whole, or at
least a major part of the surface of the article.
A number of embodiments of pantiliner according to
the invention are described below. Before doing so,
however, a description will be given of the way in
which certain relevant parameters are measured. These
are stretch, elasticity, wet through, flexibility and
thickness. Details will also be given of the synthetic
urine used in some of the tests.
r .,~, a ~a
The details of this test are set out later in this
specification.
Elasticity/Pad set
The details of this test are set out later in this
specification.
Wet throuah
2159932
14
This test measures the amount of liquid (synthetic
urine) which will pass through a product which is
permeable to air and water vapour, but substantially
impermeable to liquid, under certain conditions. The
test is carried out as follows:
(a) Place the product on a sheet of blotting paper
(220 g/mz), add 2 ml of the liquid in the centre of the
product at a flow rate of approximately 1 ml/lOsec, and
leave for 2 minutes.
(b) Place on the product a 3000 g weight having a
lower surface 100 x 50 mm, whereby to exert on the
product a pressure of 60 g/cm2 over the liquid
acquisition zone thereof.
(c) Keep the weight on the product for 15 seconds.
(d) Remove the weight.
(e) Ascertain whether any liquid has been absorbed by
the blotting paper.
(f) Repeat operations (b) to (e) nine times with a 15
second pause after each cycle.
Flexibility
This is measured by the test laid down in ASTM
Standard D 1388-64 for measuring the stiffness of
fabrics. For full details reference should be made to
that Standard. In brief, however, what is done is to
cause a strip of the material being tested to project
over an edge of a platform, until the tip of the test
specimen
W fi r
2599
is depressed under its own wight to the point where the
line joining the tip to the edge of the platform makes
an angle with the horizontal of 41.5°. The length of the
projecting portion is taken as the overhang length 0,
and the bending length c is calculated as O/2. The
flexural rigidity G is then calculated from this as:
G=Wxc3 mg. cm
This formula assumes that the weight is W in mg/cm2.
Thickness
The thickness of the pantiliners is measured under
a pressure of 20 g/cm2 (0.2845 psi).
Synthetic urine
The synthetic urine used was a solution in
distilled water of the following salts (in weight
Urea 2$, sodium chloride 0.9~, magnesium sulfate
(heptahydrate) 0.11, calcium chloride 0.06.
Details will now be given of a number of
embodiments of the invention. In so doing, the
nomenclature of Table 1 above will be used to identify
the various layers of the products. It will, however,
be noted that in Product 10 there are two adjacent
absorbent core layers, of the same materials as one
another but in different basis weights, which together
give the desired total basis weight (120 g/m2) for the
core.
219932
16
All the embodiments were hourglass in shape and had
a length of 153 mm, a maximum width of 67 mm and a
minimum width of 51 mm with all layers being of the same
size and shape, except in the case of Product 10. The
structures of Product 2 is shown in exploded isometric
view in Figure 1 of the accompanying drawings. In the
case of Product 10, the Absorbent Core (1) was smaller
in plan than the pad, having a length of 143 mm, a
maximum width of 57 mm and a minimum width of 41 mm, but
Absorbent Core (2) was the same size as the pad. The
construction of Product 10 is shown in Figure 2a, which
is a plan view, and Figure 2b, which is a cross-section
taken on line A-A in Figure 2a. In this construction,
both absorbent corers are hourglass in shape. A layer
of continuous adhesive bonds the two together, and may
also be sufficient to bond the composite core to the
topsheet, though an optional discontinuous thin adhesive
layer may be provided between Absorbent Core (1) and the
topsheet. Absorbent Core (2) is bonded to the backsheet
by lines of adhesive.
T~~~7~~-L 1
Topsheet: None
Topsheet/core adhesive: None
Absorbent core: Hydrophilic, spunlaced,
nonwoven material;
50g/m2, 70~ rayon, 30~ PET
(stretchable)
21.5993
__ m
Core/backsheet adhesive: Hot-melt, elastomeric glue(1),
20 g/m2
(elastic)
Backsheet: Hydrophobic, spunlaced,
nonwoven material;
30g/m2, 100$ PET
(stretchable)
PFA: Holt-melt Savare LA 203, 24
g/m2
Footnote (1): glue according to the patent application
identified above under the heading "Adhesive for
topsheet/core and core/backsheet".
As will be seen, Product 1 has no topsheet, and
accordingly the term "absorbent core" is to be
understood in this context as meaning simply an
absorbent member, and is not to be understood as
carrying an implication that the member concerned is
sandwiched between other members. Despite the absence of
a topsheet, the product appears to be acceptable to
users, in view of the relatively low volume of fluid
which the product is to handle. The absence of a
topsheet has the result, which can be seen from the
results which are set out below, of making the product
highly flexible.
Topsheet: Ring-rolled, apertured or
perforated film
21 5 99 3 2
1g
(stretchable)
Topsheet/core adhesive: Hot-Melt glue lines, Savare PM
17, 0.06 g/liner m.
(stretchable)
Absorbent core: Hydrophilic, spunlaced,
nonwoven material; 50 g/m2, 70$ Rayon 30~ PET
(stretchable)
Core/backsheet adhesive: Hot-Melt, elastomeric glue (1);
20 g/m2
(elastic)
-- Backsheet: Hydrophobic, spunlaced,
nonwoven material; 30 g/m2, 100$ PET
(stretchable)
PFA: Hot-Melt Savare LA203, 24 g/m2
Topsheet: Hydrophilic Elastic Perforated
Coverstock, 62 g/m2 (2)
(elastic)
Topsheet/core adhesive: Hot-Melt coated glue, Savare PM
17 , ~ 5 g/m2
(stretchable)
Absorbent Core: Creped tissue, 47 g/m2
(stretchable)
Core/backsheet adhesive: Hot-Melt, coated glue, Savare
PM 17, 20 g/m2
(stretchable)
Backsheet: Elastic film, EXX 500T"~ 38 g/m2 (3)
(3)
~:B.
19 21 5 99 3 2
(elastic)
PFA: Hot-Melt Savare LA203, 24 g/m2
Footnote (2): The material used was as described in
our copending Italian Patent Application IT 1,268,105.
Briefly, that describes a covering structure for
covering an absorbent body of an absorbent sanitary
article, the said structure having perforations which
extend therethrough and being elastic in at least one
direction, the structure comprising:
(a) an upper layer intended to face outwardly of the
absorbent body and comprising a non-woven fibrous
material;
(b) an intermediate layer comprising an elastic film;
and
(c) a lower layer intended to face inwardly towards
the absorbent body and comprising a non-woven fibrous
material; the upper and lower layers being connected
to the intermediate layer substantially only around the
perimeters of the perforations.
Footnote (3): EXX500T"~ is available from Exxon
Corporation.
Drr,r7iini-- /I
Topsheet: Hydrophilic Elastic Perforated
Coverstock, 62 g/m2 (2)
(elastic)
E
21599 3~
20
Topsheet/core adhesive: Hot-Melt coated glue, Savare PM
17, 5 g/m2
(stretchable)
Absorbent Core: Hydrophilic, spunlaced,
nonwoven material, 50 g/m2, 70$ Rayon 30$ PET
(stretchable)
Core/backsheet adhesive: Hot-Melt, elastomeric glue (1),
20 g/m2
(elastic)
Backsheet: Hydrophobic, spunlaced,
nonwoven material; 40 g/m2, 100$ PET
(stretchable)
PFA: Hot-Melt Savar~ LA203, 24 g/m2
Topsheet: Hydrophilic Elastic Perforated
Coverstock, 62 g/m2 ( 2 )
(elastic)
Topsheet/core adhesive: Hot-Melt coated glue, Savar~ PM
17, 5 g/m2
(stretchable)
Absorbent Core: Hydrophilic, spunlaced,
nonwoven material, 50 g/m2, 70$ Rayon 30$ PP
(polypropylene)
(stretchable)
Core/backsheet adhesive: Hot-Melt coated glue, Savare PM
17, 20 g/m2
(stretchable)
2I~993~
21
Backsheet: Elastic film, EXX 500 38 g/m2
(3)
(elastic)
PFA: Hot-Melt Savare LA203, 24 g/m2
Topsheet: Hydrophilic, spunlaced,
nonwoven material, 30 g/m2, 70$
Rayon 30$ PET
(stretchable)
Topsheet/core adhesive: Hot-Melt coated glue, Savare PM
17, 5 g/m2
(stretchable)
Absorbent Core: Creped tissue, 47 g/m2
(stretchable)
Core/backsheet adhesive: Hot-Melt, elastomeric glue (1),
20 g/m2
(elastic)
Backsheet: Hydrophobic, spunlaced,
nonwoven material, 40 g/m2, PET
(stretchable)
PFA: Hot-Melt Savar~ LA203, 24 g/m2
Topsheet: Ring-rolled, apertured or
perforated film
(stretchable)
Topsheet/core adhesive: Hot-Melt coated glue, Savare PM
17, 10 g/m2
(stretchable)
22
Absorbent Core: Hydrophilic, spunlaced,
nonwoven material, 70 g/m2, 70$ Rayon 30$ PP
(stretchable)
Core/backsheet adhesive: Hot-Melt, elastomeric glue (1),
20 g/m2
(elastic)
Backsheet: Hydrophobic, spunlaced,
nonwoven material, 40 g/m2, 100$ PP
(stretchable)
PFA: Hot-Melt Savare LA203, 24 g/m2
,.__,___~
Topsheet: Hydrophilic Elastic Perforated
Coverstock, 62 g/m2 (2)
(elastic)
Topsheet/core adhesive: Hot-Melt coated glue, Savare PM
17, lOg/m2
(stretchable)
Absorbent Core: Hydrophilic, spunlaced,
nonwoven material, 70g/m2, 70$ Rayon 30$ PP
(stretchable)
Core/backsheet adhesive: Hot-Melt, elastomeric glue (1),
20g/m2
(elastic)
Backsheet: Hydrophobic, spunlaced,
nonwoven material, 40g/m2, 100$ PP
(stretchable)
PFA: Hot-Melt Savar~ LA203, 24g/m2
n-_ ~L_ _L
2j599~
23
Topsheet: None
Topsheet/core adhesive: None
Absorbent Core: Hydrophilic, spunlaced,
nonwoven material, 70g/m2, 70~ Rayon 30~ PP
(stretchable)
Core/backsheet adhesive: Hot-Melt, elastomeric glue (1),
20g/m2
(elastic)
Backsheet: Hydrophobic, spunlaced,
nonwoven material, 40g/m2, 100$ PP
(stretchable)
PFA: Hot-Melt Savar~ LA203, 24g/m2
Like Product 1, this has no topsheet, and the same
comments apply as regards this fact as are set our above
in relation to Product 1.
215993
24
Product 10
Topsheet: Ring-rolled, apertured or
perforated film
(stretchable)
Topsheet/core adhesive: Hot-Melt coated glue, Savare PM
17, lOg/m2
(stretchable)
Absorbent Core (1): Hydrophilic, spunlaced,
nonwoven material, 70g/m2, 70$ Rayon 30$ PP
(stretchable)
Absorbent Core (2): Hydrophilic, spunlaced,
nonwoven material, 50g/m2, 70~ Rayon 30$ PET
(stretchable)
Core/backsheet adhesive: Hot-Melt, elastomeric glue (1);
20g/m2
(elastic)
Backsheet: Hydrophobic, spunlaced,
nonwoven material, 40g/m2, 100$ PP
(stretchable)
PFA: Hot-Melt Savare LA203, 24g/m2
Load and pad set tests
The elastic behaviour of some of the embodiments
described above (Products 1, 2 4, 7, 8 9), a
conventional pantiliner sold by Johnson & Johnson as
"Carefree Normal", and a cotton panty in which the
product of the invention might be used, were
investigated in a test described below. In this test, a
sample of each product was subjected to three hysteresis
21 5 99 3 2
cycles by means of a tensile tester designed to apply
to each sample a load which, in each cycle, gradually
increases and then gradually decreases.
Each product is first conditioned, by keeping it
for at least 12 hours in a room at a temperature of 23°
~ 2° C and a relative humidity of 50 ~ 20. A strip one
inch (2.54 cm) wide was then cut from the product the
length of the strip being either parallel to the length
of the product (if it is desired to measure MD elastic
behaviour) or perpendicular to the length of the
product (if it is desired to measure CD elastic
behaviour). In the test of which the results are given
below it was CD elastic behaviour which was measured.
The sample is laid unrestrained on a table. The
length of the part of the sample which will be tested
is marked on the sample itself. The distance between
the clamps of the tensile tester is set to the same
length that has been previously marked on the specimen.
Each sample is clamped in the tensile tester in such a
way as to enable the tester to apply a load lengthwise
of the strip and to avoid slacks or tensions. The load
cell must record increase as soon as the test starts.
The following steps were then carried out:
1. Increase the load gradually from zero up to a
value at which the length of that part of the sample
which is under load is 1250 of its initial length,
continuously recording the load and corresponding
length as this is being done.
,:
s , ; ..:
'~~ ~'~, ~l , ~',. ..
2159932
26
2. Decrease the load gradually until the distance
between the clamp returns to its starting point,
continuously recording the load and corresponding length
as this is being done.
3. Hold the sample for 30 seconds.
4. Repeat steps 1 to 3 two further times.
The results obtained are set out in Table 2 below,
except for the Carefree Normal sample, which had too
little elasticity for it to be capable of undergoing the
test, for each of the three hysteresis cycles. In each
case, the table records the peak load, i . a . the load in
g/inch required to achieve 25~ elongation, the
percentage set, i.e. the percentage amount by which the
length of the sample exceeded its original length at the
end of the each cycle at a load of 0.05 N/inch. A
value of 0.05 N, rather than zero is chosen, to avoid
possible reading problems with the computer software via
which measurements are made. The table also records the
energy dissipated in the course of the cycle. This last
value, measured in 10-3J, is determined from the area
within the hysteresis cycle.
Some of the results of Table 2, together with other
properties of the samples, are set out in Table 3.
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27
A number of points emerge from Table 2 and 3.
Firstly, it will be seen that all the Products tested
had a low value of pad set, (not more than 12$ after
three cycles, even in the worst case, and 6$ in the best
case), indicating that the Products will not lose their
elasticity in use. Secondly, Products 1, 2, 7 and 9 are
seen to be particularly advantageous in that the loads
required to reach 25~ are low, and are comparable to
those required in the case of the cotton panty.
Consequently, during use the pantiliner and panty will
stretch to substantially the same extent as one another
in response to any given force, and the pantiliner will
therefore behave, for practical purposes, as though it
were part of the panty itself.
Figures 3 to 9 are hysteresis cycles which show the
elastic behaviour of the products referred to in Table
2. As can be seen, the amount of hysteresis is not
great in the case of any of those according to the
invention, indicating that the products will retain
their elastic properties to a substantial extent during
repeated stretching and relaxation. Figure 3 is a
hysteresis cycle for the cotton panty. This can be seen
to be broadly similar to Figures 4 to 9. There is no
such cycle for the comparative article "Carefree
Normal", since this is almost completely inelastic.
