Absorbent article having increased flexibility in use

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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Details

C604S370000, C604S372000, C604S374000, C604S385010, C604S385040, C604S385310, C604S387000

Reexamination Certificate

active

06284943

ABSTRACT:

FIELD OF INVENTION
The present invention relates generally to absorbent articles such as sanitary napkins, pantiliners, and incontinence pads. More particularly, the present invention relates to sanitary napkins which are relatively stiff during placement of the sanitary napkin in an undergarment and as the undergarment is pulled into position, but which exhibit high levels of flexibility and drape during wear.
BACKGROUND OF THE INVENTION
Absorbent articles such as sanitary napkins, pantiliners, and incontinence pads are devices that are typically worn in the crotch region of an undergarment. These devices are designed to absorb and retain liquid and other discharges from the human body and to prevent body and clothing soiling. Sanitary napkins are a type of absorbent article worn by women in a pair of panties that is normally positioned between the wearer's legs, adjacent to the perineal area of the body.
It has been found desirable to construct absorbent articles which are thin, extensible, soft, and highly drapable. Such an extensible, flexible absorbent article is disclosed in PCT Application Publication No. 95/20931, published Aug. 10, 1995. These high levels of flexibility and drape provide comfortable products with low wearing awareness. To more effectively handle such articles, however, higher stiffness and rigidity are often required to prevent the end of the article from folding over as the article is placed into the undergarment and as the undergarment is pulled into position. The apparent contradiction of providing an absorbent article which is both flexible and stiff can be overcome by recognizing that the needs for stiffness and flexibility are not required simultaneously, but are needs which are separated in time.
Many current absorbent articles, particularly those with airfelt absorbent cores are soft and flexible when first placed in an undergarment, but become more stiff when wet. Such flexible-then stiff characteristics are seen in absorbent articles with other types of cores as well. U.S. Pat. No. 5,374,260 issued to Lemay, et al. on Dec. 20, 1994 discloses a sanitary napkin with a peat moss core which is flexible, then more stiff when moisture is absorbed. It is also known in the art to apply resilient structures to absorbent articles to impart an overall resiliency to the article or portions of the article. U.S. Pat. No. 5,098,422 issued to Davis, et al. on Mar. 24, 1992 describes such a form-retaining sanitary napkin. This form retaining resiliency, however, remains throughout the life of the sanitary napkin.
A need, therefore, exists for a disposable absorbent article which is relatively stiff when handled and applied to an undergarment, but which becomes more flexible when worn. Such an absorbent article has the advantage of being easy to handle and apply to an undergarment without the article folding over or adhering to itself while also offering the greatest comfort and low wearing awareness during subsequent wear. It is therefore an object of the present invention to provide an absorbent article, such as a sanitary napkin, which is relatively stiff when handled and applied to an undergarment but which becomes more flexible when worn.
This and other objects of the present invention will be more readily apparent when considered in reference to the following description and when taken in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
The present invention provides an absorbent article, such as a sanitary napkin, pantiliner, or incontinence pad. More particularly, the present invention is directed to a sanitary napkin which is generally stiff when handled and applied to an undergarment, but which becomes more flexible when worn.
The sanitary napkin comprises a liquid pervious topsheet, a liquid impervious backsheet joined to the topsheet, and an absorbent core positioned between the topsheet and the backsheet. The sanitary napkin is also provided with a stiffening feature which imparts an initial stiffness to the sanitary napkin. The stiffening feature may comprise one or more stiffening members or the stiffening feature may be provided directly by the structure of one or more of the previously named elements (i.e., the topsheet, the backsheet, and the absorbent core).
The stiffening feature of the present invention provides the sanitary napkin with a degree of stiffness when it is handled and applied to an undergarment, but not when the napkin is worn. The sanitary napkin is preferably generally flexible when worn. In a particularly preferred embodiment, the sanitary napkin is also very thin, extensible, soft, and highly drapable when worn so that it is more cloth-like and less plastic like (like many current sanitary napkins). The main body portion of this preferred napkin extends with the wearer's undergarments and provides sustained coverage of a large portion of the wearer's panties.
In a preferred embodiment, the difference in stiffness between handling the sanitary napkin and wearing the sanitary napkin is accomplished through the use of brittle strips of material which shatter when subjected to the normal forces associated with wearing of the article (e.g. from wearer sitting or walking). These strips are preferably located between the backsheet and absorbent core.
In an alternate preferred embodiment the stiffening feature may comprise a tube shaped member constructed of a tissue layer wrapped in a polypropylene layer. The polypropylene layer is preferably melted into the tissue layer to provide the requisite initial stiffness. The tube structure collapses when the wearer sits down, thereby allowing the sanitary napkin to assume a generally flexible state.
In yet an additional preferred embodiment, the stiffening feature comprises zones of stiffness which occupy at least a portion of the sanitary napkin. The zones of stiffness may be stiffened locations on the topsheet, the backsheet, the core or some combination of these. The zones of stiffness may comprise a stiffened layer of material such as a tissue layer stiffened by melting a polypropylene layer into it. This stiffened layer is then bonded to the backsheet, topsheet, or absorbent core of the sanitary napkin. The increased stiffness provided by the zones of stiffness is lost once the sanitary napkin is subjected to the normal forces of wear, thereby allowing the sanitary napkin to assume a generally flexible state.
The sanitary napkin, can, and preferably does, also comprise various additional components and/or features. For example, the sanitary napkin preferably comprises a pair of side extensions that extend laterally outward from the main body portion of the napkin.


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