Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
1999-09-30
2001-07-10
Lewis, Aaron J. (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S385030, C604S385230, C604S385010, C604S387000
Reexamination Certificate
active
06258997
ABSTRACT:
TECHNICAL FIELD
The invention pertains to a liquid pervious cover layer for an absorbent article such as a diaper, an incontinence protector, a sanitary napkin or the like, which exhibits a liquid-pervious carrier layer having a first surface and a second surface, wherein the first surface of the carrier layer exhibits a multitude of individually arranged fibres, each fibre exhibiting a first fibre end and a second fibre end, and being attached with one fibre end against the first surface of the carrier layer. The invention also relates to an absorbent article provided with the cover layer and to a method for manufacturing of the cover layer.
TECHNICAL BACKGROUND
High demands on both softness and dryness are made on liquid-pervious cover layers for absorbent articles of this type, which are intended to bear on the body of the user during use.
However, it has proved to be difficult to achieve a liquid-pervious cover layer with 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-pervious cover layers for absorbent articles, is that the fibre structure of the material absorbs liquid when the cover layer is wetted. A certain amount of the liquid is not conducted downwards to the underlying absorbent structure, but remains in the liquid-pervious cover layer instead. Since the liquid-pervious cover layer bears on the body of the user during use, 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 during use, leads to an increased risk of skin irritations and infections.
The most important reason for some of the liquid remaining in the fibre structure is that textile materials usually consist of an irregular fibre structure with fibres or fibre filaments oriented in 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 material plane. Also liquid which is not absorbed into the fibre capillaries is conducted along the fibre structure in the direction of the material plane, and is collected in cavities between the fibres in which the liquid is retained without being able to spread further to underlying material. These factors result in a certain amount of liquid remaining in the cover layer and causing a wet surface closest to the user.
Another problem with the nonwoven materials of today, having fibres substantially oriented in parallel with the material plane, is that the possibility to control the wetting course by means of utilizing the properties of the fibres, such as for example the wettability of different fibres, is limited. Furthermore, the possibility to control the wetting course is limited when it comes to the location of the fibres and their design.
It is previously known from U.S. Pat. No. 3,967,623 to use a liquid-pervious cover layer, consisting of a perforated plastic layer, as a carrier material onto 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 remains that the liquid transfer from the fibres to the underlying absorbent body inside is poor, which results in the surface closest to the user remaining wet after 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 by fibres which are attached at an angle to 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 fused fibre fixation layer on the plastic film. The plastic film may be perforated so that the material becomes liquid-pervious. The fibres are 0.3 to 2.5 mm long and the thickness may be varied with regard to 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 plane of the material and thereby 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. With this previously known cover layer, however, the problem of achieving a dry surface, when the layer is used as a liquid-pervious surface material on an absorbent article, still remains.
SUMMARY OF THE INVENTION
By means of the present invention, the problems with achieving a liquid-pervious cover layer for absorbent articles, which is soft and exhibits a dry surface also after wetting, has essentially been eliminated.
Accordingly, by means of the invention, a soft, skin-friendly and textile-like cover layer for an absorbent article has been achieved, which layer has the ability to conduct liquid downwards to an underlying absorbent structure and to thereby maintain a dry surface closest to the user.
A liquid-pervious cover layer according to the invention is primarily distinguished by that the carrier layer exhibits a plurality of regions which are substantially free from fibres and which each occupies a surface such that a circle having a diameter of 3 to 15 mm and preferably having a diameter of 3 to 10 mm can be accommodated within each fibre-free region.
The fibre-free regions of the cover layer allow liquid to pass between the hydrophobic fibres, through the liquid pervious cover layer. At the same time, the hydrophobic fibres provide a soft, skin-friendly surface, isolating absorbed liquid from the user's skin when the cover layer is being used as a liquid-pervious topsheet on an absorbent article.
A cover layer in accordance with the invention has been found to perform particularly well when the hydrophobic fibres are 0.3-2.5 mm long and preferably 0.3-1.5 mm long.
The fibres can be arranged in a wide variety of different surface patterns such as squares, bands, stars, flowers, dots, rings, etc. Mixed patterns and patterns having varying fibre densities can also be used. When the fibres are arranged in stripes or band-shaped regions, the distance between two neighboring fibre-covered regions should be in the order of 3-15 mm and preferably 3-10 mm.
In order to achieve the desired liquid-permeability, it has been shown that the total area of the fibre-free regions should occupy at least 25% of the surface of the carrier layer. However, the fibre-free regions should not occupy more than 60% and preferably not more than 50% of the surface.
The advantage with such a cover layer is that the hydrophobic surface of the individual fibres creates a dry barrier between the liquid-pervious carrier layer and the user. This implies that the risk that the surface bearing most closely on the user is perceived as wet after wetting is reduced.
According to the invention, the individual fibres are attached only to delimited regions of the total area of the carrier layer, while other regions of the surface of the carrier layer thus are left free from individual fibres. For instance, the individual fibres can be attached in a row pattern along the longitudinal direction of the article. The advantage with such a pattern is that the liquid is distributed from the wetting point in a direction towards the end portions of the article, whereas liquid spreading in the lateral direction is counteracted. Thereby, the risk of the region around the wetting point being saturated with liquid, with leakage in a lateral direction as a consequence, is reduced. A further advantage, with liquid distribution from the wetting point of the article to the end portions of the article, is that the liquid distribution in an underlying absorbent structure becomes more uniform. This results in a better utilization
Johansson Anette
Ljungqvist Nils
Lewis Aaron J.
SCA Hygiene Products AB
Shanoski Paul
Young & Thompson
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