Panty liner

Details Panty liner Panty liner

2002-03-22

2004-03-23

Lo, Weilun (Department: 3761)

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

C604S367000

Reexamination Certificate

active

06710219

ABSTRACT:

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.
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.
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 negatively influenced primarily in a high humidity environment at room temperature. In order to ensure that the lactobacillus have a healthy storage environment, there has been developed a packaging unit which is sufficiently impervious to prevent the ingress of moisture during the storage period (WO 00/01207). The product is also subjected to a drying stage immediately prior to packaging the product, so as to ensure that the moisture content of the product will be sufficiently low when the package is sealed. This additional process step is, however, complicated and expensive. Consequently, there is a need for another production process or another lactobacillus-containing product that can provide for the lactobacillus a good and dry environment that is effective in ensuring healthy survival of the bacteria during storage.
The object of the present invention is to provide an absorbent article, primarily a panty liner, which enables the active additives to retain their activity prior to use of the product, without requiring further treatment, such as drying of the product to a greater or lesser extent.
SUMMARY OF THE INVENTION
This object is fulfilled with a panty liner that contains active additives, such as lactobacillus, 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 also an intermediate absorbent layer and optionally a fastener means, characterised in that the panty liner is produced chiefly from one or more low hygroscopic materials chosen from group of materials: non-woven, wadding, tow, and other synthetic fibre materials, wherein the moisture content of the panty liner is less than 2.5% after twenty-four hours at 22.5° C. in an humidity of 46%, preferably less than 2.0%, and more preferably less than 1.0%.
It has been found that under normal conditions such a panty liner will not absorb moisture to an extent that will have a negative effect on the healthy survival of the lactobacillus during storage. The panty liner may also include a superabsorbent for absorbing fluid that must, of necessity, be taken-up, such as menstruation fluid, this amount corresponding to 2-4 g fluid in normal cases. Thus, the superabsorbent material, which is applied in the core of the product, will take-up the fluid that must be taken-up in order for the product to fulfil 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 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.
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 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 sup

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