Wetlaid unitary stratified composite

Details Wetlaid unitary stratified composite Wetlaid unitary stratified composite

2000-07-21

2003-12-30

Ruhl, Dennis (Department: 3761)

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

C604S374000, C604S378000

Reexamination Certificate

active

06670522

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an absorbent composite and methods for making the same and, more particularly, to a unitary stratified composite having a first stratum and a second stratum integrally connected by a transition zone.
BACKGROUND OF THE INVENTION
Cellulose fibers derived from wood pulp are used in a variety of absorbent articles, for example, diapers, incontinence products, and feminine hygiene products. It is desirable for the absorbent articles to have a high absorbent capacity for liquid, as well as to have good dry and wet strength characteristics for durability in use and effective fluid management. In addition to absorbent capacity, the ability to rapidly absorb a liquid is a desirable characteristic of an absorbent article. For example, diapers and other hygienic products that do not contain a dedicated liquid acquisition component, suffer from liquid leakage and rewet (i.e., the feeling of dampness to touch after use). Hygienic products that contain only a high loft nonwoven acquisition layer suffer from a lack of fast temporary liquid storage capability and leakage. Hygienic products that contain cellulose-based acquisition layers suffer from rewet due to the temporary storage capability of the cellulose's fibers and lack of complete drainage. Further, cellulose-based acquisition materials have poor wet and dry integrity.
One solution to the problem of providing absorbent articles that possess the advantageous properties of high absorbent capacity, rapid liquid acquisition, reduced leakage, and superior rewet performance has been the production of absorbent articles that contain multiple layers. For example, the combination of one layer having rapid liquid acquisition characteristics with another layer having high absorbent capacity results in a product that offers the advantages of both strata. Some improvements in the performance of products that include multiple layers have been directed to the integration of the layers. Approaches to increased integration typically include methods of bonding one layer to the next. Increasing the commingling between, for example, a liquid acquisition layer and a liquid storage layer can increase fluid communication and the -rate -and drainage efficiency at which the acquisition layer releases liquid to the storage layer, thereby increasing the product's overall liquid containment capability.
Despite the advantages associated with multiply layered absorbent products, problems related to the effective layer-to-layer fluid communication of diverse materials, and the economic costs of producing, handling, and bonding individual component layers remain.
Accordingly, there exists a need for an integrated absorbent material that provides the dry feel and rapid liquid acquisition of a high-loft, nonwoven material, and rapid temporary storage capability and rapid liquid acquisition performance of cellulose fibers such as crosslinked cellulose pad. The present invention seeks to fulfill these needs and provides further related advantages.


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Anonymous, “Thermally Bonded Absorbent Structures Having Discrete, Stepped Density Zones in the Z-Dimension,”2244 Research Disclosure, No. 374, Emsworth, GB, Jun. 1995, pp. 387-390.

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