Absorbent articles having reduced outer cover dampness

Details Absorbent articles having reduced outer cover dampness Absorbent articles having reduced outer cover dampness

1997-12-19

2002-04-09

Weiss, John G. (Department: 3761)

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

C604S372000, C604S378000, C604S385010

Reexamination Certificate

active

06369292

ABSTRACT:

TECHNICAL FIELD
The present invention relates to absorbent articles. More particularly, the present invention relates to absorbent articles, such as personal care products, that have reduced outer cover dampness.
BACKGROUND OF THE INVENTION
Absorbent articles, such as infant diapers, adult incontinence garments, sanitary napkins, bedpads, panty liners, incontinent pads, and the like are well known in the art. These articles are inexpensive, often disposable, and yet capable of absorbing and retaining fluids and other bodily discharges. These absorbent articles typically have an outer cover having a liquid-impermeable plastic film, such as polypropylene and/or polyethylene, to prevent the retained discharge from leaking from the article and soiling items of clothing, bedding, furniture, and the like. However, until recently liquid-impermeable outer covers often employed a film which was impervious to water vapor as well as liquids. Because the outer cover was impermeable to both liquids and water vapor, the absorbent article often felt hot and clammy to the wearer even prior to absorbing any bodily discharge. Furthermore, this lack of permeability to water vapor often caused irritation of the skin and in some cases severe dermatological problems. For example, absorbent articles such as diapers may cause diaper rash on infants when worn for considerable periods of time. In addition to concerns over skin wellness, the liquid impermeable plastic films employed as outer covers often lacked the aesthetic and tactile qualities desired in personal care products such as disposable diapers.
In response to the problems described above, breathable cloth-like liquid-impermeable outer covers have been developed. Such structures, typically laminates of several different sheets, remain substantially impervious to liquids but are “breathable” in the sense that water vapor will pass through the outer cover. Breathable outer covers have become increasingly popular and more highly commercialized in absorbent personal care products, particularly in connection with disposable diapers. However, while providing a healthier and more comfortable product from the wearer's perspective, breathable liquid-impervious outer covers often suffer from an unwanted and unpleasant outer cover dampness. Continued use of an absorbent article after fluid has been discharged and absorbed by the article can, even after a short time, cause the outer cover to develop a wet or damp feel. However, this unpleasant wet feeling is not typically due to permeation of liquid through the liquid-impermeable cover or leakage from the article but is simply condensation of water vapor on the outer cover as a result of excess water vapor passing through the outer cover.
Thus, there exists a need for an absorbent article which allows sufficient water vapor permeation for absorbent articles to remain a healthy and comfortable product for the wearer but which does not allow excessive water vapor permeation after discharge of fluid into the article such that the outer cover develops a wet or damp feel.
SUMMARY OF THE INVENTION
The present invention addresses the difficulties and problems discussed above as well as problems experienced by those skilled in the art by providing an absorbent article comprising: (a) a breathable liquid-impervious outer cover; (b) a liquid pervious topsheet; (c) an absorbent body between the outer cover and topsheet; and (d) a hydrophobic barrier layer positioned between the breathable outer cover and the absorbent body. The hydrophobic barrier layer can comprise one or more layers of porous material having a supported hydrohead value at least 18 cm and a bulk of at least about 0.012 inches (0.03 cm) and further wherein the outer cover and barrier layer collectively have an inverted-WVTR of less than about 15,000 g/m
2
/day. Desirably the porous material has a hydrohead of at least 30 mbar and, still further, comprises a fibrous material such as a woven fabric or nonwoven web. In a further aspect, hydrophobic barrier layer can comprise a nonwoven web having a Frazier air permeability over 20 cubic feet per square foot per minute. The barrier layer may comprise, in one aspect, one or more nonwoven webs of meltblown fibers having a collective basis weight of over 16 g/m
2
(grams per square meter). In still a further aspect, the barrier layer can comprise a plurality of layers, including a layer of meltblown fibers, wherein the plurality of layers have a collective basis weight in excess of about 20 g/m
2
, desirably having a basis weight from about 25 g/m
2
to about 40 g/m
2
. In a further aspect, the hydrophobic barrier layer may comprise at least one spunbond layer and one meltblown layer.
In a further aspect, the absorbent article includes a hydrophobic barrier layer that extends under substantially the entire portion of the absorbent body. For example, the hydrophobic barrier layer can extend beyond outer edges of the absorbent body or only along the length of the central portion of the absorbent article. In a further aspect, the barrier layer may comprise at least in part a portion of a wrapsheet about the absorbent body. For example, the wrapsheet can comprise a hydrophobic barrier layer over a first side of the absorbent body adjacent the outer cover and a hydrophilic nonwoven layer over the opposed side of the absorbent body adjacent the topsheet. Alternatively, the wrapsheet can comprise a continuous sheet having a hydrophobic portion adjacent the liquid-impervious outer cover and a hydrophilic portion over the opposed side of said absorbent body and adjacent the topsheet such that the hydrophobic portion of the wrapsheet comprises at least part of the hydrophobic barrier layer.


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