Topsheet for body fluids absorbent article

Stock material or miscellaneous articles – Structurally defined web or sheet – Including aperture

Reexamination Certificate

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Details

C428S131000, C428S132000, C428S913000, C604S358000, C604S378000, C604S383000, C604S385010

Reexamination Certificate

active

06274218

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a topsheet for a body fluids absorbent article such as a disposable diaper, an incontinent pad, training pants, a sanitary napkin and the like.
Japanese Patent Application Disclosure Gazette (Kokai) No. Hei4-152945 discloses a topsheet for such purpose which is made of thermoplastic synthetic resin and a plurality of liquid-passages extending therethrough from its upper surface to its lower surface. Each of the liquid-passages has a higher density at its lower end than along its peripheral wall.
The known topsheet is based on a phenomenon that an amount of body fluids discharged on the topsheet rapidly transfer from a region of the topsheet having a relatively low fiber density toward a region of the topsheet having a relatively high fiber density. Specifically, through the liquid-passages of the topsheet, the body fluids transfers towards the lower ends of the respective liquid-passages having the relatively high density. These lower ends are usually kept in close contact with a liquid-absorbent core of the body fluids absorbent article and therefore the body fluids rapidly transfer from the lower ends into the absorbent core. The body fluids absorbent article using such a topsheet certainly allows the body fluids to be rapidly absorbed by the absorbent core without giving a wearer uncomfortable feeling of wetness. However, the wearer's body weight exerted on the liquid-absorbent core during use of the article causes the body fluids to flow back from the absorbent core toward the wearer's skin.
SUMMARY OF THE INVENTION
In view of the problem as has been described above, it is an object of the present invention to provide a topsheet improved so as to alleviate an uncomfortable feeling due to the back flow of the body fluids and at the same time to maintain the advantageous property achieved by the topsheet such that the body fluids can rapidly transfer to the liquid-absorbent core.
According to the present invention, there is provided a topsheet for body fluids absorbent article comprising: a sheet having an upper surface intended to be placed against a wearer's skin; a lower surface underlying the upper surface; a plurality of liquid-pervious apertures extending between the upper and lower surfaces; the topsheet having an upper part defined by a first fibrous layer and a lower part defined by a second fibrous layer having a density higher than that of the first fibrous layer; and around each of the apertures, the first and second fibrous layers being integrated together so that the topsheet has a density progressively increasing from the upper surface towards the lower surface and, at least in proximity of the lower surface, has a density further higher than in the second fibrous layer.
According to an embodiment of the present invention, a lower surface of the first fibrous layer and an upper surface of the second fibrous layer are intermittently bonded together by means of hot melt adhesive.
According to another embodiment of the present invention, the first fibrous layer and the second fibrous layer are hydrophilic and the second fibrous layer has a hydrophilicity higher than a hydrophilicity of the first fibrous layer.
According to still another embodiment of the present invention, the first fibrous layer is hydrophobic and the second fibrous layer is hydrophilic.
According to further another embodiment of the present invention, at least one of the first and second fibrous layers is formed by a nonwoven fabric.
According to yet another embodiment of the present invention, the first fibrous web has a basic weight of 10~30 g/m
2
and the second fibrous web has a basic weight of 10~100 g/m
2
and a density corresponding to at least 1.3 times of the first fibrous web.
The topsheet according to the present invention comprises the upper fibrous layer intended to be placed against a wearer's skin, the lower fibrous layer having a density higher than a density of the upper fibrous layer, and the apertures each having a density along its peripheral wall as well as in the proximity of thereof progressively increasing from the upper surface to the lower surface of the topsheet. Such feature advantageously facilitates the body fluids to transfer towards the absorbent core. Furthermore, it is difficult for the body fluids partially exuding from the absorbent core to transfer back towards the upper surface of the topsheet having a relatively low density. The upper surface of such topsheet can always remain dry and therefore can effectively alleviate an uncomfortable feeling of wetness from which a wearer of the conventional body fluids absorbent article has often suffered.


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