Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
1999-05-26
2003-02-18
Ruhl, Dennis (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
Reexamination Certificate
active
06521813
ABSTRACT:
TECHNICAL FIELD
The invention pertains to a liquid acquisition layer for an absorbent article such as a sanitary napkin, an incontinence protector, a diaper, a panty-liner, a bed protector or the like, which exhibits a carrier layer against which individual fibres, detached from each other and each exhibiting two fibre ends, are attached with one fibre end against the carrier layer with an attachment angle &agr; between the carrier layer and each individual fibre. The invention also relates to an absorbent article provided with the liquid acquisition layer.
BACKGROUND OF THE INVENTION
Great demands are made on both softness and dryness of liquid acquisition layers for absorbent articles of the herein intended type, which are intended to be in contact with the body of the user during use.
However, it has proved to be difficult to achieve a liquid acquisition layer having a soft and textile-like surface which at the same time remains dry during use.
One problem, when using nonwoven materials or other similar textile materials as liquid acquisition layers for absorbent articles, is that the fibre structure of the material absorbs liquid when the cover layer is wetted. A certain quantity of the liquid is not conducted downwards to the underlying absorbent structure, but remains instead in the liquid receiving cover layer. Since the liquid receiving cover layer is in contact directly against the body, such articles are perceived as being wet and uncomfortable to wear already after an initial wetting. Furthermore, the wet surface which is in direct contact with the skin results in an increased risk of skin irritation and infections.
The main reason for part of the liquid remaining in textile cover layers is that such textile materials usually consist of an irregularly shaped fibre structure with fibres or fibre filaments directed along the plane of the material. This implies that excreted body fluid, by means of the capillary action of the fibres, is distributed along the fibre structure in the direction of the plane of the material. Also liquid which is not absorbed by the fibre capillaries is conducted along the fibre structure in the plane of the material and is collected in voids between the fibres, where the liquid remains without being able to be further distributed to materials on the inside. These factors result in a certain amount of the liquid remaining in the cover layer and create a wet surface closest to the user.
Another problem with the present nonwoven materials, having fibres primarily directed along the material plane, is that the possibility to control the wetting course, by utilizing different types of fibres exhibiting differences in properties such as for example wettability, is limited. Furthermore, the possibility to control the wetting course is limited where the location of the fibres and their design are concerned.
Particularly with regard to the sanitary napkins and panty-liners of today, which should be discreet to wear during use, another problem is that such articles, in order to obtain a liquid absorbent structure and at the same time maintain a dry surface closest to the user, are built up from a number of layers exhibiting essentially different properties. This implies that such articles are rather voluminous and therefore often are perceived as being uncomfortable and indiscreet. A further disadvantage with having a number of layers is that the material consumption for these disposable articles is high, which results in a high manufacturing cost and a high usage of raw material.
From U.S. Pat. No. 3,967,623 it is known to use a liquid-pervious cover layer consisting of a perforated plastic layer as a carrier material, on which fibres treated with wetting agent are applied in order to create a soft and fluffy surface. The individual fibres are oriented so that they are directed upwards towards the user during use and are approximately 5 mm long. Since the fibres are directed upwards towards the user, a soft and fluffy surface is created. However, the problem that the liquid transfer from the fibres to the absorbent body on the inside is poor remains to be solved, which results in the surface closest to the user remaining wet after the initial wetting.
BE 09300552 relates to a cover layer for an absorbent article, which cover layer consists of a plastic film, which at least on one side is covered with fibres which are not fused together and which are attached at an angle towards the plastic film. In order to obtain such a structure the fibres may, for example by means of flocking, be attached with one of their fibre ends against a melted fibre fixation layer on the plastic film. The plastic film can be perforated so that the material becomes liquid-pervious. The fibres are between 0.3 and 2.5 mm long and the thickness may vary depending on how soft the layer should be. Different fibres may be used, such as for example viscose, cotton, polyethylene, polypropylene, polyester, and polyamide. The risk of the liquid spreading in the material plane, and consequently along the surface of the cover layer, is minimal with this previously known cover layer. Furthermore, the cover layer exhibits a soft surface closest to the user. However, the problem of achieving a dry surface remains with this previously known cover material, when the layer is used as a liquid-pervious surface material on an absorbent article.
SUMMARY OF THE INVENTION
The problems with achieving a liquid acquisition surface, for, for example, liquid-pervious cover layers intended for absorbent articles or for liquid acquisition articles, such as for example a panty-liner, which liquid acquisition surface is soft and exhibits a dry surface also after wetting, have been substantially eliminated by the present invention.
Accordingly, a soft, skin-friendly and textile-like liquid acquisition layer for an absorbent article has been achieved by means of the invention, which layer has an ability to conduct the liquid downwards in the structure and, by means of this, to maintain a dry surface closest to the user.
A liquid acquisition layer according to the invention exhibits a carrier layer against which separate fibres, detached from each other and each exhibiting two fibre ends, are attached with one fibre end against the carrier layer with an attachment angle &agr; between the carrier layer and each individual fibre. The liquid acquisition layer is primarily characterized in that the individual fibres comprise at least a first fibre type and a second fibre type. Since the fibres are not bonded together into a nonwoven fabric but instead are oriented so that an angle arises between the fibre and an underlying carrier material, accordingly, increased possibilities are obtained to design a cover layer which utilizes the properties of different fibres, for example the liquid-conducting ability of different fibres.
According to a preferred embodiment, the fibres of the first fibre type are longer than the fibres of the second fibre type. Thereby, the fibres of the first fibre type are suitably 0.3-1.5 mm long, while the fibres of the second fibre type are 1.5-5 mm long. The fibre length is dependent on the other properties of the fibres, such as for example their liquid absorption ability. Furthermore, the fibre length is dependent on which type of absorbent article the liquid acquisition layer is intended for, since urine and menstrual fluid are different from each other, among other things with regard to viscosity and surface energy. This implies that the length of the fibres must be adapted to these conditions in order to achieve an optimum liquid acquisition layer with regard to dryness and softness.
According to one embodiment, the longer fibres are more hydrophobic than the shorter fibres. Since the longer fibres which are located closer to the skin of the user during use are more hydrophobic than the shorter fibres, a distance is created between the skin and the shorter liquid-absorbing fibres. Accordingly, the more hydrophillic fibres are constituted by fibres which exhibit a lower contact ang
Ruhl Dennis
SCA Hygiene Products AB
Truong Linh
Young & Thompson
LandOfFree
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