Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Nonwoven fabric – Including strand or fiber material which is stated to have...
Reexamination Certificate
1998-11-13
2003-07-08
Juska, Cheryl A. (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Nonwoven fabric
Including strand or fiber material which is stated to have...
C442S361000, C442S362000, C442S400000, C442S401000, C442S417000
Reexamination Certificate
active
06589892
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to nonwoven web composites of improved cohecency which exhibit a combination of excellent durability, absorbency, and/or other desirable properties. More specifically, the invention is directed to nonwoven web composites containing a bicomponent filament matrix having adhesive properties, and a third component selected from fibers and particles contained within the matrix.
BACKGROUND OF THE INVENTION
Bicomponent nonwoven filaments are known in the art generally as thermoplastic filaments which employ at least two different polymers combined together in a heterogeneous fashion. Instead of being homogeneously blended, two polymers may, for instance, be combined in a side-by-side configuration, so that a first side of a filament is composed of a first polymer “A” and a second side of the filament is composed of a second polymer “B.” Alternatively, the polymers may be combined in a sheath-core configuration, so that an outer sheath layer of a filament is composed of a first polymer “A,” and the inner core is composed of a second polymer “B.” Alternatively, the polymers may be combined in an islands-in-the-sea configuration in which one or more islands of a first polymer “A” appear in a sea of a second polymer “B.” Other heterogeneous configurations are also possible.
Bicomponent filaments offer a combination of desired properties. For instance, certain polypropylene resins yield filaments which are strong but not particularly soft. Certain polyethylene resins yield filaments which are soft but not particularly strong. By combining both resins together in the form of bicomponent nonwoven filaments, a hybrid combination of strength and softness can be achieved.
Bicomponent filaments have been disclosed in combination with carbon particles, zeolites, ion exchange resins, carbon filters, sterilizing fibers, and/or gas adsorbing fibers for use in specialized filters. U.S. Pat. No. 5,670,044, issued to Ogata et al., discloses the use of bicomponent meltblown filaments in these combinations, for use in cylindrical filters. In that case, the bicomponent filaments contain high and low melting polymers. The filaments of the filter are stacked and bonded together by melting only the lower melting component.
Pulp fibers have been employed in certain absorbent applications to enhance the absorbency. U.S. Pat. No. 4,530,353, issued to Lauritzen, discloses pulp fibers in combination with staple length bicomponent fibers used in the manufacture of absorbent bandages. In that case, the fibers also contain high and low melting polymers. The staple length fibers are bonded together by melting only the lower melting component.
In applications where a third component selected from fibers and/or particles is combined with a bicomponent filament web, the bicomponent filaments act as a matrix which ensnares, entraps, and contains the third component. In some of these applications (for instance, absorbent applications where the third component is an absorbent), there is a need or desire to increase the amount of the third component in order to maximize the properties that it contributes to the nonwoven web composite. There is also a need or desire to improve the containment properties of the bicomponent filament matrix at all levels of third component loading.
SUMMARY OF THE INVENTION
The present invention is directed to an improved nonwoven web composite including a matrix of bicomponent thermoplastic filaments and a third component selected from fibers, particles, and combinations thereof contained within the filaments. The nonwoven web composite exhibits improved containment of the third component, permitting higher loading of the third component as well as improved durability at all loading levels. The present invention is also directed to an absorbent article, including a personal care absorbent article, which utilizes the improved nonwoven web composite of the invention.
The bicomponent thermoplastic filaments contain at least first and second thermoplastic polymer components, arranged in distinct segments or zones across the width of the filament. At least one of the thermoplastic polymers possesses adhesive properties with respect to the third component, or is modified to possess adhesive properties with respect to the third component. The adhesive properties may be imparted by either a) employing an adhesive polymer for at least one of the distinct thermoplastic polymer segments in the bicomponent filaments, which segment is exposed at the filament surface, b) modifying a non-adhesive polymer by blending it with an adhesive polymer and employing the blend for one of the distinct polymer segments in the bicomponent filaments, which segment is exposed at the filament surface, or c) surface-modifying the bicomponent filaments or a segment thereof by spraying, dipping, or otherwise applying an adhesive material effective to bond the bicomponent filaments to the third component.
With the foregoing in mind, it is a feature and advantage of the invention to provide a nonwoven web composite containing a filament matrix and a loaded component (fibers and/or particles) within the matrix, having improved durability and stability due to adhesion between the filament matrix and loaded component.
It is also a feature and advantage of the invention to provide an absorbent nonwoven web composite capable of containing high loadings of absorbent fibers and/or particles, due to adhesion between the absorbent material and the nonwoven thermoplastic filament matrix which contains it.
It is also a feature and advantage of the invention to provide an absorbent article having improved absorption and durability, due to better continence of absorbent fibers and/or particles within a nonwoven filament matrix, and a higher loading capacity for the absorbent fibers and/or particles.
DEFINITIONS
The term “nonwoven fabric or web” means a web having a structure of individual fibers or threads which are interlaid, but not in a regular or identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, air laying processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91.)
The term “microfibers” means small diameter fibers having an average diameter not greater than about 75 microns, for example, having an average diameter of from about 1 micron to about 50 microns, or more particularly, having an average diameter of from about 1 micron to about 30 microns. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9000 meters of a fiber. For a fiber having circular cross-section, denier may be calculated as fiber diameter in microns squared, multiplied by the density in grams/cc, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, the diameter of a polypropylene fiber given as 15 microns may be converted to denier by squaring, multiplying the result by 0.89 g/cc and multiplying by 0.00707. Thus, a 15 micron polypropylene fiber has a denier of about 1.42 (15
2
×0.89×0.00707=1.415). Outside the United States the unit of measurement is more commonly the “tex,” which is defined as the grams per kilometer of fiber. Tex may be calculated as denier/9.
The term “spunbonded fibers” refers to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine capillaries of a spinnerette having a circular or other configuration, with the diameter of the extruded filaments then being rapidly reduced as by, for example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat.
Clark Darryl Franklin
Creagan Christopher Cosgrove
Duellman Justin Max
Haynes Bryan David
Marmon Samuel Edward
Juska Cheryl A.
Kimberly--Clark Worldwide, Inc.
Pauley Petersen Kinne & Erickson
Pratt Christopher C.
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