Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
2001-03-06
2004-04-06
Lo, Weilun (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
Reexamination Certificate
active
06717029
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to absorbent articles, and to methods for preparing the same. In particular, the absorbent articles include cores characterized by a Distribution Index or Distribution Index profile to provide improved absorbency, improved cost efficiency and/or other superior characteristics.
BACKGROUND OF THE INVENTION
Traditionally, disposable absorbent garments such as infant diapers and training pants, adult incontinence products, and other such products are constructed with a moisture-impervious outer backing sheet, a moisture-pervious body contacting inner lining sheet, and a moisture-absorbent core sandwiched between the liner and backing sheets.
Much effort has been expended to develop cost-effective absorbent cores that display optimal liquid absorbency and retention. In many applications, it is desirable to form an absorbent article having a zoned absorbency profile where different predetermined regions have different basis weights of fibers per unit area, and, therefore, different absorbencies. Such variation in basis weight across a fibrous article can, for example, enhance the efficiency of the fibrous article in end usage as disposable diapers and sanitary napkins.
For example, U.S. Pat. No. 4,685,915 to Hasse et al. discloses a disposable diaper wherein a central portion of its absorbent core has a higher density and higher basis weight per unit area than longitudinally placed end portions of the absorbent core. The disclosed absorbent cores may comprise a mixture of hydrophilic fibers and discrete particles of a highly absorbent material such as, for example, hydrogel material. The absorbent cores are described as having a central portion that is preferably substantially uniformly dense and of uniform basis weight throughout its extent, and where the ratio of the average density of the central portion to the average density of each of the end portions is about 2 to 1 or greater, and more preferably, 2.5 to 1 or greater.
U.S. Pat. No. 5,849,002 to Carlos et al. discloses a disposable diaper in which the absorbent core material is distributed in such a way that three zones are made inside of it, one of liquid reception, a zone of distribution-storage, and finally an anti-leakage zone. The reception zone is described as being placed where generally the user discharges urine while using the diaper. This zone is described as being less dense and has a lower specific gravity than the distribution-storage zone that fully surrounds it, in such a way that when liquid flows into the reception zone it is immediately absorbed and flows towards the distribution-storage zone, which will distribute the liquid to every zone of the diaper and where it will then remain until the diaper is disposed.
U.S. Pat. No. 5,817,079 to Bergquist et al. discloses absorbent products having discrete areas of dry fibrous materials such as fluid-repellent materials that are precisely placed in various plains within the product so as to provide barriers to bodily fluid leakage from the product. A preferred embodiment is described as having hydrophilic fibers placed around the parameter of a central absorbent area of an absorbent product to discourage and/or prevent side or end leakage from the product.
U.S. Pat. No. 5,098,423 to Pieniak et al. discloses a disposable diaper that is particularly configured for improved fit and comfort, as well as to provide enhanced absorptive capacity and leakage-resistant characteristics. The disposable diaper is described as having improved fit and comfort that is achieved by providing the diaper with a relatively thin, narrow absorbent panel, with the panel configured to provide desirably high absorbency efficiency for enhanced performance characteristics. The diaper is described as having an absorbent panel that is configured to exhibit sufficient and inherent absorbency to provide an impact zone with an absorbent efficiency index of at least 1.5. This absorbency efficiency index is determined by ascertaining the absorptive characteristics of a diaper's absorbent panel as it relates to the bulk of the panel. The absorbency efficiency index relates to the relationship between the diaper bulk and absorptive capacity. This index is described as being determined by dividing the urine volume at the 90
th
percentile level in the impact zone (of a mid-size diaper) by the volume of the impact zone absorptive medium. The impact zone is defined as the 6 inches of panel located at the second and third fifths of the panel length, as measured from the front of the diaper.
U.S. Pat. No. 4,997,428 to Linnebur et al. discloses a hygienic disposable article used as diaper, which possesses an absorbent body enhanced with expandable material. The article is described as having expandable material that is to be applied along the direction of the longitudinal access of the diaper, in decreasing quantity outward from the crotch area in such a way that the concentration of the expandable material in the crotch area is 8% to 40% of the weight of the absorbent body, while in the area of the waist it is 1% to 7% thereof. The disposable article is described as achieving an optimal distribution of the absorbent components of the diaper in accordance with the distribution pattern of the fluid excreted from the wearer.
In the general practice of forming fibrous materials as absorbent articles, including absorbent cores, it has become a practice to utilize a fibrous sheet of cellulosic fiber's, or other suitable fibers, which is fiberized in a conventional fiberizer or other device to form discrete fibers. The discrete fibers which then are entrained in an air stream or airflow and directed to a forming surface whereon the fibers are deposited to form a pad of fluff, i.e. a non-woven mat of randomly arrayed fibers containing substantial interstitial void space and being highly compressible in character.
The forming surface utilized in such system typically is constructed as a wire or screen grid and typically employs pneumatic flow means such as a vacuum suction apparatus to define a differential pressure zone on the forming surface and impose a pressure differential thereon. The air in the air entrained fiber stream is passed through the openings or perforations in the screened grid of the forming surface. The use of vacuum suction to draw the air entrained fiber stream to the forming surface, with the passage of the air component through the forming surface, is highly efficient and lends itself to high speed commercial operations.
In the prior practice of forming laid fibrous articles, various means have been provided in the art for providing the fibrous article with gradiations or variations in basis weight across the surface thereof. Various means, have been proposed for producing gradiations of basis weight.
For example, U.S. Pat. No. 4,388,056 to Lee et al. (“the '056 patent”) discloses an apparatus for continuously forming an air-laid fibrous web, comprising a laydown drum having a circumferentially segmented annular-shaped plenum comprising a multiplicity of circumferentially placed transverse plenum segments, and a partially masked foraminous laydown surface having oppositely contoured, cyclically undulating side edges defining cyclically circumferentially placed relatively wide masked and relatively narrow masked transverse areas of the surface, which together define the radially outward facing boundary of the plenum. Constant differential pressure means are employed for drawing air through the foraminous laydown surface and the plenum from an air-entrained-fiber deposition chute as the drum is rotated. The specific improvement described in the '056 patent comprises stationary adjustable air flow modulating means (shutter plates) disposed adjacent the radially inwardly disposed boundary of an arcuate portion of the plenum circumferentially spanning a plurality of the transverse plenum segments. In such manner, the pressure across the relatively widely masked transverse sections of the laydown surface can be adjusted witho
Hunton & Williams LLP
Kidwell Michele
Lo Weilun
Paragon Trade Brands, Inc.
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