Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
2002-02-14
2004-02-03
Lo, Weilun (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S372000, C604S382000, C604S381000
Reexamination Certificate
active
06685686
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an absorbent article such as a diaper, an incontinence guard, a pantyliner, or a sanitary napkin comprising a liquid-pervious topsheet, a liquid-impermeable backsheet and an absorbent body enclosed therebetween, wherein said topsheet and absorbent body either directly or via at least one intermediate layer are joined by means of a first adhesive.
BACKGROUND OF THE INVENTION
An absorbent article, such as a diaper, an incontinence guard or a sanitary napkin, normally comprises a liquid-pervious topsheet, a liquid-impermeable backsheet, and an absorbent body enclosed therebetween. Typically, the topsheet is glued to the backsheet by means of a hydrophobic adhesive.
In order to achieve a surface facing towards the user, which has an improved liquid-absorption, different treatments have been proposed for enabling the topsheet to let liquid pass through more rapidly to the underlying absorbent body. Nonwoven materials, which often are utilised as topsheets are, as a rule, substantially hydrophobic. These materials can be treated, for example, with surfactants in order to render the material more hydrophilic. However, after wetting of the material, the surfactant is washed away and the topsheet becomes hydrophobic once again. Thereby, the liquid transport through the material is deteriorated.
EP 0 822 794 discloses a method for achieving a three-dimensional structure having ridges and valleys on an article which consists of a liquid-impermeable backsheet, an absorbent core, and a liquid-impermeable topsheet. The topsheet with the underlying absorbent body are provided with a pattern by means of embossed rolls and which create a pattern comprising said ridges and valleys. This topology is intended to guide the liquid down into the absorbent core. In a second rolling treatment, a penetrating agent is applied in order to neutralize the hydrophobic fibres in the topsheet and create contact, in the form of hydrophilic flow lines, with the hydrophilic fibres in the absorbent body.
However, a prerequisite for a good transport of liquid from the topsheet to the absorbent body is that said layer really is in contact with the absorbent body, either directly or via an underlying liquid transfer layer. An air gap may be created between the topsheet and the absorbent body or, alternatively, there may be air between the three different layers constituted of the topsheet, the underlying liquid transfer layer and the absorbent body, something that considerably impairs the liquid aqcuisition into the absorbent body. In order to ensure that the absorbent body really contacts and remains in contact with the topsheet, the topsheet and the absorbent body can be joined by means of an adhesive. For this purpose, either a hydrophobic or a hydrophilic adhesive can be utilised.
SE 503 798 discloses an absorbent article where the topsheet is glued to the absorbent body by means of a hydrophilic adhesive in order to achieve a surface, which more easily lets liquid through. However, the surface may be perceived as somewhat moist by the wearer during usage.
WO 98/42290 discloses an article, which exhibits a three-dimensional structure having slightly raised flat regions, and recessed regions. Across the raised regions, a hydrophobic material has been applied on top of the topsheet, which causes the liquid to pass down into the recessed regions. This product, however, has the disadvantage that the hydrophobic material has to be applied on the topsheet, something that requires an additional step in the production of absorbent articles when the choice of material and equipment is concerned.
Accordingly, there is a need for a product which provides a rapid liquid acquisition and which the user perceives as having a dry surface.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a product which has good liquid absorption ability, and which still exhibits a dry surface facing towards the user. This object is achieved by means of using a second adhesive, which is more hydrophobic than said first adhesive, for joining said topsheet and absorbent body, either directly or via at least one intermediate layer. The liquid which is to be absorbed is guided from the more hydrophobic regions created in this way, which repel an aqueous solution, to the comparatively more hydrophilic regions, where the liquid is directed further down to and is absorbed into the absorbent body.
Preferably, the first and the second adhesive are arranged in patterns, wherein the pattern of the first adhesive, at least to a substantial extent, does not coincide with the pattern of the second adhesive, but is displaced in relation to this.
According to another aspect of the invention, the adhesively joined portion of the topsheet, alternatively together with at least one intermediate layer, which overlaps the absorbent body, can be formed into a three-dimensional structure. This results in a product, which preferably has raised hydrophobic regions and recessed hydrophilic regions. The liquid that is to be absorbed is guided down onto the hydrophilic recessed regions where the liquid will be absorbed into the underlying absorbent body, whereas the hydrophobic raised regions will contain less liquid. Consequently, those raised regions that are in closest contact with the skin of the user will be perceived as more dry.
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patent: 0 970 710 (2000-01-01), None
patent: 1 022 007 (2000-01-01), None
patent: 0 822 794 (2000-07-01), None
patent: 1 065 047 (2001-01-01), None
patent: 503 798 (1996-04-01), None
patent: 96/33679 (1996-10-01), None
patent: 98/42290 (1998-10-01), None
patent: WO 2/34188 (2002-05-01), None
Hermansson Kent
Roxendal Sofia
Lo Weilun
SCA Hygiene Products AB
Stephens Jacqueline
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