Stock material or miscellaneous articles – Structurally defined web or sheet – Including aperture
Reexamination Certificate
1997-04-11
2001-05-15
Cole, Elizabeth M. (Department: 1771)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including aperture
C428S137000, C428S138000, C428S195100
Reexamination Certificate
active
06231948
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a web which is suitable for use as a fluid transport mechanism. In particular, the web is designed to facilitate fluid transport in a preferential direction from one surface toward another surface and resist fluid transport in the opposite direction.
BACKGROUND OF THE INVENTION
It has long been known in the field of disposable absorbent articles that it is extremely desirable to construct absorptive devices, such as disposable diapers, sanitary napkins, incontinent briefs, bandages, wound dressings, and the like, presenting a dry surface feel to the user to improve wearing comfort and to minimize the potential for development of undesirable skin conditions due to the prolonged exposure to moisture absorbed within the article. Accordingly, it is generally desirable to promote rapid fluid transfer in a direction away from the wearer and into a retentive structure, while resisting fluid transfer in the reverse direction.
One viable prior art solution to the aforementioned problem has been to utilize a covering or topsheet on the exposed, wearer-contacting surface which comprises a web of formed, apertured thermoplastic film. Conuonly assigned U.S. Pat. No. 4,342,314, issued to Radel et al. on Aug. 3, 1982, the disclosure of which is hereby incorporated herein by reference, discloses a representative formed film of this variety. Such webs utilize capillary fluid transport to conduct fluid away from one surface (wearer-contacting) into and through the web via three-dimensional capillaries formed into the material, and then into the underlying absorbent structure. In order to address consumer concerns with regard to plastic-like appearance and feel, webs of this variety have been developed which include an interconnected structure of fiber-like appearance in the interest of generating a more cloth-like, aesthetically-pleasing appearance. In addition, apertured, formed thermoplastic film webs have been developed which further include microscopic surface texturing (microtexture) and/or microscopic apertures (microapertures) to further enhance the visual and tactile impression of such webs. Representative film webs of this variety are discloses in commonly assigned U.S. Pat. No. 4,463,045, issued to Ahr et al. on Jul. 31, 1984, and U.S. Pat. No. 4,629,643, issued Dec. 16, 1986 to Curro et al., the disclosures of which are hereby incorporated herein by reference.
Another viable prior art solution has been to utilize a fibrous material as a covering or topsheet on such articles, alone or as an overlay or laminate over other materials. A representative topsheet structure of this variety is disclosed in commonly assigned Published PCT Application WO 93/09741, published May 27, 1993 naming Aziz et al. as inventors, the disclosure of which is hereby incorporated herein by reference. Such fibrous materials may take the form of a woven or nonwoven web of a suitable fiber variety, and may or may not include discretely formed apertures in addition to the inherent porosity of the web itself. Webs of this variety also exhibit capillary fluid transport characteristics via the three-dimensional capillaries formed by inter-fiber spaces, likewise conducting fluid away from the wearer-contacting surface and into the underlying absorbent structure. Such webs exhibit an aesthetically-pleasing, cloth-like surface appearance and tactile impression due to the fibrous nature of the surface.
While capillary webs of the foregoing vareies are effective in transporting fluid, their effectiveness is limited in that such capillary structures can only move fluid once it reaches the capillary interior. Fluid which wets and remains on wearer contacting surfaces contributes to a “wet” tactile feeling or impression, and to the extent that such fluid may be colored or opaque also contributes to a “stained” visual impression. Surface textures naturally occurring in the material of the web or imparted thereto in formation further increase the likelihood that residual fluid will be trapped or retained on the wearer-contacting surface rather than entering capillary structures for transport away from the surface. Thus, surface topographies which contribute to desirable visual and tactile impressions when dry can also tend to retain residual fluid on the exposed surface and thus reduced desirability under in-use conditions.
Accordingly, it would be desirable to provide a web with enhanced effectiveness in transporting fluid away from one surface which is initially contacted by a fluid.
More particularly, it would be desirable to retain visual and tactile properties of webs having fibrous or otherwise textured surfaces while promoting more rapid and more complete fluid transport away from the wearer-contacting surface and into the interior of an associated absorbent article.
SUMMARY OF THE INVENTION
The present invention pertains, in a preferred embodiment, to a fluid-pervious web comprising a first or wearer-contacting surface and a second or garment-facing surface. The web is particularly well suited for use as a topsheet on a disposable absorbent article. The first and second surfaces are separated from one another by an intermediate portion. The first surface of the web provides a structure which exhibits a surface energy less than the surface energy of the intermediate portion. In a preferred embodiment the web exhibits a plurality of regions of comparatively low surface energy which define surface energy gradients where they interface with higher surface energy web surfaces.
More particularly, the present invention pertains to a fluid-pervious web having a plurality of small-scale surface energy gradients which are oriented and located so as to effectively transport fluid away from the first or wearer-contacting surface. The web essentially retains its visual, tactile, and physical properties of the substrate material while achieving the desired surface energy properties.
Fluid transport webs according to the present invention preferably include discontinuous, spaced regions defining small scale surface energy gradients on the first surface to aid in small scale fluid movement toward apertures or capillary entrances for transport away from the first surface. Such webs also preferably include small scale surface energy gradients normal to the first surface within a capillary structure to aid in moving fluid away from the first surface and into the capillaries for capillary fluid transport.
The present invention also pertains to absorbent articles which preferably include a topsheet, a backsheet secured to the topsheet, and an absorbent core positioned between the topsheet and the backsheet, wherein the topsheet exhibits surface energy gradients according to the present invention.
REFERENCES:
patent: 0 255 209 A2 (1988-02-01), None
Burchnall John B.
Haney A. Renee
Langdon Frederick M.
Lee Yann-Per
Ouellette William R.
Andes William Scott
Cole Elizabeth M.
Johnson Kevin C.
Milbrada Edward J.
The Procter & Gamble & Company
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