Note: Descriptions are shown in the official language in which they were submitted.
CA 02441935 2003-09-22
WO 02/076363 PCT/SE02/00574
1
A PANTY LINER
FIELD OF INVENTION
The present invention relates to panty liners that contain active additives,
such as
lactobacillus, and comprise a liquid-permeable top sheet which lies proximal
to the wearer
in use, a liquid-impermeable backing sheet which lies distal from the wearer
in use and
possibly an intermediate absorption layer and possibly also fastener means.
1 o BACKGROUND OF THE INVENTION
In recent times, various types of active additives have begun to be used in
absorbent
products, such as diapers, panty liners and the like. Examples of such
additives are
deodorants such as zeolites and silica described in WO 97/46188, WO 97/46190,
WO
97/46192, WO 97/46193, WO 97/46195 and WO 97/46196, for example. These
additives
are intended essentially to act in the product per se. Another example resides
in the
addition to diapers of softening additives, for example lotions, that are
intended to be
transferred from the product to the wearer's skin.
2o Active additives are intended to impart new or enhanced properties to the
absorbent
product in some respect. Lactic acid forming bacteria (lactobacillus)
(mentioned in SE
9703669-3, SE 9502588-8, WO 92/13577, SE 9801951-6, SE 9804390-4, WO 00/01206
and WO 00/01207, among others), are applied to that part of the absorbent
product which
lies proximal to the wearer in use and are intended to be transferred to the
wearer's genitals
as a supplement to the wearer's own lactobacillus. This is particularly of
value in situations
where the own lactobacillus flora is weakened. For example, females of a
fertile age
naturally have lactobacillus in their genitals as a defence against undesired
micro-
organisms.
Since lactic acid forming bacteria (lactobacillus) are living organisms, and
indeed must be
alive in order to carry out their desired functions, it is important that the
environment in
which it such bacteria are present does not have a negative influence on their
survival. This
has been found problematic with regard to the development of products that
include
lactobacillus as an active component. It has been found that the survival of
lactobacillus is
CA 02441935 2003-09-22
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negatively influene~, primexily in a high humidity environment at room
temperature. In
order to ensure that the lactobacillus have ~ healthy storage environraeat,
there has been
dwelaged a. packaging unit which is sufficiently impervious to prevent .the
ingress of
moisture during the storage period (WO o~~al2aT~. The graduct is also
subjected to a
drying stage immediately prior to packaging the pmdu~ct, so as to ensure that
the moisttue
content of the produce will be sufficiently lotw when the~ackage is sealed.
This additional
procress step u, hov~aever, complicated and experuive.~Cunsefuently, there is
a need for
anothea~produetion process or another lactobacillus-containing product tlsat
can provide for
the lactobacillus a good and dry eaviromnent that is affective in ensuring
healthy survival
of the bacteria during smrage.
The object of the present invention i3 to pratride an absorbent article,
priman'1.y a panty
liner, which enables the active additives to retain their activity prior to
use of the product,
wi~aut tequ~ing further treatment, s~uch_ as drying of the product to , a
greater or Iessa.
extent. ~ ~lse~j '~Pf12~5'~~ t d,~tc~.oscs. cz.r, weti~~-a.~4ov~.rw~ ~ ~
cvr~~r~'s~ ~ - .
_~c~cA~o~;ufi tXt~ ~ swti ~.~b K. ~a.c~t.,-~ -
._._t . . _ ~~_ ~ . Tie t~ cow~pr,~sc.s.
SInKM~IRY OF T'HE fNYEhITIO~N .urs~er -~-c v~~~:y.~ cbe'v~s,: ~a,~.Y or
pa'~ywsr ,.
'Ibis object is fulfilled with a panty liner that aantain9 active additives,
such as
zn Iactobaciilus, and that comprises a liquid permeable top sheet which lies
proximal to the
wearer in use, a liquid-impermeable backing sheet which lies distal from the
wearer in use,
optionally aisa~- an i~ermediate absorbent layer and optionally a fastener
means,
clharnsed, in that the peaty liner is produced chiefly fmm one or more law
hygroscopie
materials chosen from group of materials: ran-waver, wadding, tow, and other
synthetic
1 25 fibre materials, wherein the moiatum eont~eat of the panty liner is less
rhea ~.5°~a after
twenty-four horns at 2~.5°C is an humidity of 4~°Ia, preferably
less than 2.0°/a, and mare
pIefera~lly leSB thdll ~ .~°I'°.
It has been found that uade~c normal conditions such a panty liner will not
absorb moistum
3a to as extent that will have a negative c$ect on the healthy Survival of the
lactobacillus
during storage. The paslty Iiner may also include a superabsorbent for
absorbing fluid that
must, a~ necessity, be taken-up, such as menstruation fluid, this amount
Gorrespanding to
2-4 g fluid is narm8l cases. Thus, tht superabsarbent material, which is
applied in the care
of the pnaduett will take=up the fluid that must be taken-up nn older far the
product to fulfil
AMENDED SHEET
r . . _ _ .__ ._.Y... .~ _ ... r _ c _ . .ncr~ n rvr~
CA 02441935 2003-09-22
WO 02/076363 PCT/SE02/00574
3
its function in use. Although the remaining synthetic tow or wadding material
has no
appreciable hygroscopic capacity, it has a highly effective dry content at
room temperature,
which provides the lactobacillus with a dry environment during storage.
Paper based materials of different kinds are normally used in typical products
of this kind.
For example, pulp fibres, among other things, are most often used in the core
of the article,
because besides being hydrophilic, such fibres absorb moisture and liquid
effectively and
are inexpensive. By avoiding the use of paper fibres, as in the case of the
present invention,
there is achieved a lower moisture content in the product and therefore a
higher survival
1 o rate of the lactobacillus. A sufficiently effective absorption capacity is
obtained in the
product with the use of superabsorbents that have the capacity of absorbing
anticipated
volumes of liquid discharged in use, i.e. a typical volume of about 0-4 ml. In
this case, the
liquid take-up is concentrated at the core and the remainder of the panty
liner is made of
material that does not tend to absorb moisture.
The superabsorbent material used may have the form of small SAP grains, large
SAP
grains, or SAF (superabsorbent fibres). The absorbency of the article with
respect to body
fluids will therewith be sufficient without having the capacity to take-up an
unnecessarily
large amount of atmospheric moisture.
According to one embodiment, the product contains no superabsorbent, which is
functional
in those cases where no fluid is expected to be absorbed in use. This
particularly applies to
those cases in which it is only desired to transfer the lactobacillus to the
wearer in use.
The product may conveniently be provided with a breathable backing sheet, so
that less
perspiration will be produced when wearing the product, and so that the
product will not
take-up an unnecessarily large amount of moisture.
DETAILED DESCRIPTION OF THE INVENTION
By low hygroscopic material is meant material that is able to take-up
atmospheric moisture
in an amount sufficiently low to maintain a substantially dry environment
under normal
storage conditions, for example material such as tow, wadding and other
synthetic fibre
materials.
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By tow is meant here a synthetic material consisting of long polypropylene
fibres that have
been bonded by transversal welds so as to hold the material together.
Wadding is a synthetic high loft material which, for instance, is needled by
thin air, resin
bonded, thermobonded, or bonded by carded or combed fibres. Wadding is
available
commercially from, e.g., Libertex.
The inventive panty liner is comprised of a liquid-permeable top sheet, a
liquid-
impermeable backing sheet, and optionally an intermediate absorbent body. The
active
additives, preferably lactobacilli are applied in the close proximity of the
top sheet. In
order to ensure that the lactobacilli will survive and retain their activity
until the product is
used, it is important in accordance with the inventive concept that the
material from which
the panty liner is made will attract as little moisture as possible. Trials
have shown that a
moisture content of 2.5 weight-% is an upper limit value beneath which
survival of the
is lactobacilli is good. Consequently, an inventive panty liner is made of
material which will
absorb less moisture than said upper limit under tested conditions (see
Example 1), such as
wadding and tow, for instance.
Superabsorbent (SAP) is preferably used in order to satisfy those absorption
requirements
that can arise in use. When a superabsorbent is used, it may also be
beneficial to apply a
dispersion layer beneath the top sheet, in order to ensure that the liquid
delivered by the
wearer is led to the superabsorbent material.
In one embodiment, the low hygroscopic material is tow.
In another embodiment, the low hygroscopic material is wadding.
In another embodiment, the top sheet and the wadding are joined together by
punctiform
bonds or by linear bonds that form a pattern. This is achieved by welding or
by applying a
3o high pressure at points, along short lines (dashes) or in some other
pattern, wherewith the
width of the points or lines in the pattern is about 1-7 mm. This results in a
combination of
larger and smaller capillaries that promote liquid absorption and
transportation of liquid to
lower layers.
CA 02441935 2003-09-22
WO 02/076363 PCT/SE02/00574
In a further embodiment, the low hygroscopic material is thick non-woven, for
example
carded, spun-bonded, or a white or brown non-woven, "Evolon" having splittable
fibres,
with a weight per unit area of 80-140 g/m2, available from Freudenburg, or
microfibres.
5 The superabsorbent material used in the inventive panty liner may have the
form of SAP
grains, e.g. Hysorb C 7100 from BASF, acid SAP, or SAF fibres. The
superabsorbent
material is applied in an amount in which it is able to absorb 0-6 g liquid,
preferably 2-4 g
liquid. This requires an addition of 0.1-0.5 g superabsorbent.
In one embodiment, the panty liner contains no superabsorbent.
When conditioning the inventive panty liner over a period of twenty-four hours
and at a
temperature of 22.5°C and a humidity of 46%, the panty liner will have
a moisture content
that is lower than 2.5%, preferably lower than 2.0%, and most preferably lower
than 1.0%.
By active additive is meant a substance, an agent or a composition that is
applied to the
absorbent article during its manufacture and that is intended to change or
improve the
function of the article in some way or another. Examples of active additives
are
deodorisers such as zeolite and silica, softeners, such as lotions,
lactobacillus for inhibiting
2o the cultivation of other micro-organisms, and acids, such as lactic acid
and citric acid, acid
SAP, and partially neutralised SAP which is intended to lower the pH and
thereby inhibit
bacterial growth. The active additive may, for instance, be a micro-organism.
According to
one preferred embodiment of the invention, the active additive is an acid-
producing micro-
organism. According to a more preferred embodiment of the invention, the
active additive
is a lactobacillus and more preferably a lactobacillus of the strain
Lactobacillus plantarum
LB 931 (deposition No. (DSM): 11918).
When the active moisture-sensitive additive is lactobacillus, the additive can
be applied in
the form of a freeze-dried powder containing lactobacilli, or in the form of a
suspension
that contains lactobacilli. In this regard, it us suitable to keep the water
content as low as
possible or the concentration of lactobacilli as high as possible in the
suspension, so as to
avoid the addition of unnecessary water that must be later dried off.
Lactobacilli will
preferably be applied in an appropriate quantity of 104-101', preferably 106-
10'°
CFU/product (CFU: Colony Forming Unit).
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The liquid-permeable top sheet is comprised of a soft skin-friendly material.
The top sheet
may be comprised of a layer of different types of non-woven fibre material, or
most
beneficially of tow or wadding. Other materials that can be used are
perforated plastic
films, plastic nets, stitched, crocheted or woven textiles, and combinations
and laminates of
these types of materials. The plastic may be a thermoplastic, for instance
polyethylene
(PE). The non-woven material may consist of synthetic fibres, such as
polyethylene (PE),
polypropylene (PP), polyurethane (PU), a polyester, nylon or regenerated
cellulose, or a
mixture of different fibres. All materials that are used for liquid-permeable
top sheets in
the production of absorbent articles, such as sanitary napkins, panty liners
or incontinence
t 0 guards, can be used for the liquid-permeable top sheet of the inventive
article, and it will
be understood that the aforesaid materials have only been given by way of
example,
provided that they have effective acquisition properties.
The liquid-impermeable backing sheet consists of a flexible material,
preferably a thin film
of polyethylene (PE), polypropylene (PP) or a polyester, although it may
alternatively
consist of a laminate of liquid-permeable material, such as non-woven, wadding
or tow,
and a liquid-impermeable material. All materials used in liquid-impervious
backing sheets
for absorbent articles may be used. The backing sheet may, beneficially, be
air-permeable.
When using superabsorbents, it is normally necessary to include in the
absorbent article a
dispersion layer for leading the liquid to be absorbed from the top surface of
the article to
the superabsorbent polymers. These polymers are normally comprised of paper
fibres
(cellulose fluff), which is hydrophilic and has capillarity. According to the
invention, the
dispersion layer is conveniently comprised of synthetic fibre wadding, which
is not
hydrophilic and therefore does not absorb liquid to the same extent as
cellulose fluff. Such
a dispersion layer also includes capillaries for dispersing the liquid that is
absorbed.
Wadding includes relatively large capillaries or pores and when these
capillaries or pores
are, e.g., welded to a surface material, there are created smaller
capillaries/pores that have
a greater liquid retention capacity. The presence of a dispersion layer
reduces the risk of
3o discharged fluid running to and over the edge of the panty liner and
therewith discolouring
the panties or other garments of the wearer. It can be suitable to include a
liquid acquisition
layer (dispersion layer), even when the top sheet itself has good liquid
acquisition
properties.
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With respect to packaging of the inventive panty liner, reference is made to
packages and
packaging methods disclosed in WO 00/01207.
The panty liner has a length of 60-260 mm. The absorption body has a widest
width of 30
80 mm, preferably about 70 mm, and a smallest width at its rear end of 5-20
mm,
preferably about 10 mm.
The panty liner is produced conventionally, for example in length-wise
production in a
one-path or four-path continuous production line.
to
A number of devices can be used to fasten the panty liner to the wearer's
panties, such as
tabs, flaps (wings), adhesive strings or friction surfaces. The panty liner
will preferably
include flaps or wings that can be folded around the edge of the wearer's
panties and
therewith fold the liner in place. The flaps, or wings, may be provided with
adhesive
strings that are covered with release paper in their packaged state, such
release paper
consisting of silicone-coated paper that functions to protect the adhesive
strings against
contaminating substances, such as dust, dirt and the like, and also prevents
said strings
from drying-out prior to use. Alternatively, it is conceivable to replace the
adhesive strings
with friction coatings or the like in the region of the absorbent body.
Moreover, solely one
flap may be provided with adhesive strings, although it is then necessary for
the flaps to be
dimensioned so that they will mutually overlap subsequent to being folded-in
against the
underside of the wearer's panties, or after having been folded around the
edges of the
panties. Fastener devices other than adhesive may be used to fasten the panty
liner to the
wearer's panties, e.g. hook devices of the touch-and-close fastener type
capable of co
acting with the textile material from which the panties are made.
Although the invention is primarily concerned with a panty liner, it will be
understood that
the inventive concept also includes other absorbent articles in which active
additives are
used.
The invention will now be described by way of an example, although it will be
understood
that the example ahs no limiting effect on the scope of the invention.
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Example 1
The moisture uptake of a number of material combinations was examined by
conditioning
the tested material samples over a period of twenty-four hours and at a
temperature of
22.5°C and a humidity of 46% (Table 1). Two independent tests were
carried out with each
material sample. The commercially available product "Grace" (also called
Libresse Air)
was used as a reference. This product includes polypropylene non-woven surface
material,
140 grams of thermo-bonded LDA (Low Density Air-laid), and a breathable
backing sheet
of microporous polyethylene. The tests showed that all of the materials chosen
exhibited
values beneath 2.5% moisture content (with respect to weight), with the
exception of the
chosen reference material.
Sample Sample content
Moisture content
~ 5 1 NW * * + tow material with 1 g large SAP grain 0.65%; 0.76%
2 NW** + tow material with 1 g small SAP grains 1.10%; 1.00%
3 NW** + tow material with SAF 2.42%; 2.18%
4 NW** + tow 0.70%; 1.43%
5 NW* + surface material with wadding 2.39%; 1.04%
6 Brown Evolon (thick non-woven) 2.34%; 2.42%
7 Reference* - Libresse Air 3.78%; 3.72%
*NW is carded material Terpol (26g/m2) from Tenotex.
**NW is spun-bonded 20g/m2 from BBA NW.
Table 1. Moisture take-up test. Conditioning of the samples over twenty-four
hours at
22.5°C and 46% humidity. All panty liners in the table have a PE
backing sheet. The
percentage values are in weight-%.
