Low-density, substantially non-wicking layers for absorbent...

Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...

Reexamination Certificate

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C604S385300, C604S385230, C604S385250, C604S367000, C604S374000, C604S375000, C604S378000, C604S385010

Reexamination Certificate

active

06545195

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to an absorbent composition for absorbent articles such as diapers, incontinence products, training pants, sanitary napkins, and the like. In particular, the present invention is directed to absorbent articles, having unexpectedly superior absorbent properties, comprising a substantially non-wicking layer disposed between a substantially impermeable backsheet and a permeable topsheet, said substantially non-wicking layer comprising foam having a density of no greater than about 0.01 g/cc and a compressional rigidity at about 10% strain of at least about 4 kPa.
BACKGROUND OF THE INVENTION
Disposable absorbent articles typically include a moisture-impervious backing sheet, an absorbent pad, and a liner sheet that contacts the body of a person wearing the article. In addition, elasticized regions are provided around the edges of the article to secure the article about the waist and legs of a wearer. Diapers typically further comprise opposed front and rear waist portions defining a waist opening, a crotch portion disposed there between, and a pair of elastically contractible leg openings along the side edges of the crotch portion. Disposable diapers having elasticized margins for placement about the legs of a wearer are disclosed in U.S. Pat. No. 4,050,462 and U.S. Pat. No. 5,092,861. An absorbent article having elasticized side margins and waist band margins are shown in U.S. Pat. No. 4,300,562.
Despite previous advancements in the field of absorbent articles, persons of ordinary skill in the art continue their efforts to produce absorbent articles having better absorbency and that are thus are better able to contain urinary and fecal excretions. For instance, problems with prior diaper designs include inferior absorbency and leakage of urinary or fecal material from the article. Prolonged contact of liquid or semi-solid excreta with the skin of the wearer is also a continuing problem in the art. For example, the moisture vapor and heat generated by the bodily exuded trapped within a diaper may lead conditions adjacent to wearer's skin which promotes skin irritation, infection, and the like. Various approaches to improve the absorbency of absorbent articles have been attempted, including the incorporation of foams as acquisition layers in the absorbent articles.
For example, U.S. Pat. No. 5,147,345 to Young et al. discloses absorbent articles, such as diapers, for the management of incontinence. Such articles utilize in their absorbent cores a fluid acquisition/distribution component and a fluid storage/redistribution component maintained in fluid communication with the acquisition/distribution component. The fluid acquisition/distribution component can be any porous hydrophilic, e.g., fibrous or foam-based, material which will provide an initial Fluid Acquisition Rate of at least 2 mL of synthetic urine per second and will also preferably provide a 30-minute Vertical Wicking Height of at least 2 cm. The fluid storage/redistribution component comprises a hydrophilic, flexible, open-celled polymeric foam having a free absorbent capacity of at least about 12 mL of synthetic urine per gram of dry foam and an absorbent capacity under a 5.1 kPa confining pressure which is at least 5% of this free capacity. Preferred fluid acquisition/distribution component materials comprise chemically stiffened, twisted, curled cellulosic fibers. Preferred fluid storage/redistribution component materials comprise absorbent foams prepared by polymerizing a high internal phase emulsion (HIPE).
U.S. Pat. No. 5,318,554 to Young et al. discloses absorbent articles, such as diapers, for the management of incontinence. Such articles utilize in their absorbent cores an fluid acquisition/distribution component and a fluid storage/redistribution component maintained in fluid communication with the acquisition/distribution component. The fluid acquisition/distribution component can be any porous hydrophilic, e.g., fibrous or foam-based, material which will provide an initial Fluid Acquisition Rate of at least 2 mL of synthetic urine per second and will also preferably provide a 30-minute Vertical Wicking Height of at least 2 cm. The fluid storage/redistribution component comprises a hydrophilic, flexible, open-celled polymeric foam having a free absorbent capacity of at least about 12 mL of synthetic urine per gram of dry foam and an absorbent capacity under a 5.1 kPa confining pressure which is at least 5% of this free capacity. Preferred fluid acquisition/distribution component materials comprise chemically stiffened, twisted, curled cellulosic fibers. Preferred fluid storage/redistribution component materials comprise absorbent foams prepared by polymerizing a high internal phase emulsion (HIPE).
U.S. Pat. No. 5,268,224 to Des Marais et al. discloses absorbent foam materials suitable for use as or in the absorbent cores of absorbent articles, such as diapers which absorb and retain aqueous body fluids. Such foam materials comprise hydrophilic, flexible open-celled structures which are preferably prepared by polymerizing high internal phase (HIPE) water-in-oil emulsions. Such foam materials have a pore volume of from about 12 to 100 mL/g, and a capillary suction specific surface area of from about 0.5 to 5.0 m.sup.2/g. These materials also exhibit a resistance to compression deflection such that a confining pressure of 5.1 kPa produces after 15 minutes a strain of from about 5% to 95% compression when the material is saturated at 37 degrees Celsius to its free absorbent capacity with synthetic urine.
U.S. Pat. No. 5,331,015 to DesMarais et al. discloses absorbent foam materials suitable for use as or in the absorbent cores of absorbent articles, such as diapers which absorb and retain aqueous body fluids. Such foam materials comprise hydrophilic, flexible open-celled structures which are preferably prepared by polymerizing high internal phase (HIPE) water-in-oil emulsions. Such foam materials have a pore volume of from about 12 to 100 mL/g, and a capillary suction specific surface area of from about 0.5 to 5.0 m.sup.2/g. These materials also exhibit a resistance to compression deflection such that a confining pressure of 5.1 kPa produces after 15 minutes a strain of from about 5% to 95% compression when the material is saturated at 37 degrees Celsius to its free absorbent capacity with synthetic urine.
U.S. Pat. No. 5,851,648 to Stone et al. discloses absorbent foams materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).
U.S. Pat. No. 5,786,396 to Stone et al. discloses absorbent foams materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foams also give up this fluid efficiently to higher absorption pressure storage materials, including foam-based absorbent fluid storage components, without collapsing. These absorbent foams are made by polymerizing high internal phase emulsions (HIPEs).
U.S. Pat. No. 5,632,737 to Stone et al. discloses absorbent foams materials that are capable of acquiring and distributing aqueous fluids, especially discharged body fluids such as urine. These absorbent foams combine relatively high capillary absorption pressures and capacity-per-weight properties that allow them to acquire fluid, with or without the aid of gravity. These absorbent foam

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