KR20070097449A - Absorbent structure with aggregate clusters - Google Patents

Abstract

An absorbent structure has a macro absorbent structure with a plurality of aggregate clusters intermixed therein. The aggregate clusters have a periphery, an interior, and thermoplastic binder fibers. The thermoplastic binder fibers have thermoplastic binder fiber ends. The thermoplastic binder fiber ends are located at the periphery of the aggregate clusters. The interior of the aggregate clusters are substantially free of thermoplastic binder fiber ends. The macro absorbent structure and the aggregate clusters may also include thermoplastic binder fibers, staple fibers, superabsorbent particles and the like. A method of making absorbent structures includes a first absorbent structure, dividing the first absorbent structure to create aggregate clusters, providing a stream of the aggregate clusters, providing polymeric fibers, merging the aggregate cluster stream and polymeric fiber stream into a single product stream, and making a second absorbent structure. The method may further include staple fibers, superabsorbent particles, and the like.

Description

ABSORBENT STRUCTURE WITH AGGREGATE CLUSTERS

Disposable absorbent articles include a variety of applications including disposable diapers, training panties, disposable swimwear shorts, adult incontinence garments, feminine hygiene products, wound dressings, lactation pads, bed pads, wipes, bibs, wound dressings, surgical capes or drapes, etc. Used for example. Such disposable absorbent products are generally suitable for absorbing a number of substances, such as water and body exudates such as urine, menstrual discharge, blood, and the like.

Some disposable absorbent articles are formed of densified cellulose intermixed with superabsorbent particles. Others are formed from high integrity absorbent structures comprising high concentrations of superabsorbent particles intertwined or mixed with thermoplastic long fibers and / or cellulose fibers to improve wearability, comfort and / or performance. In general, absorbent structures, in particular high integrity structures, can be mechanically constrained or restricted so that the absorbent structure cannot be fully expanded in the presence of a liquid. In addition, high integrity absorbent structures can be costly due to the addition of thermoplastic fibers.

Therefore, there is a need for an absorbent structure, including a high integrity absorbent structure that can expand more fully in the presence of a liquid and is more efficient in terms of manufacturing cost.

Summary of the Invention

In light of the above-mentioned demands, the present invention provides an absorbent structure having aggregate clusters, and a method for producing an absorbent structure having aggregate clusters.

In various embodiments, the absorbent structure includes a macro absorbent structure. The macro absorbent structure includes a plurality of aggregate clusters intermixed within the macro absorbent structure. The aggregate cluster includes thermoplastic binder fibers having an outer edge and an interior and having thermoplastic binder fiber ends. The thermoplastic binder fiber end is located at the outer edge of the aggregate cluster. The interior of the aggregate cluster is substantially free of thermoplastic binder fiber ends. The macro absorbent structure includes thermoplastic binder long fibers and superabsorbent particles bound to the thermoplastic binder long fibers. In such embodiments, the aggregate cluster comprises superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster, staple fibers bound to the thermoplastic binder fibers in the aggregate cluster, or superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster. It can include both staple fibers.

In various other embodiments, the absorbent structure includes a macro absorbent structure. The macro absorbent structure includes a plurality of aggregate clusters intermixed within the macro absorbent structure. The aggregate cluster includes thermoplastic binder fibers having an outer edge and an interior and having thermoplastic binder fiber ends. The thermoplastic binder fiber end is located at the outer edge of the aggregate cluster. The interior of the aggregate cluster is substantially free of thermoplastic binder fiber ends. The macro absorbent structure includes thermoplastic binder long fibers and staple fibers bound to the thermoplastic binder long fibers. In such embodiments, the aggregate cluster comprises superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster, staple fibers bound to the thermoplastic binder fibers in the aggregate cluster, or superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster. It can include both staple fibers.

In other embodiments, the absorbent structure includes a macro absorbent structure. The macro absorbent structure includes a plurality of aggregate clusters intermixed within the macro absorbent structure. The aggregate cluster has a thermoplastic binder fiber having an outer edge and an inside and having thermoplastic binder fiber ends. The thermoplastic binder fiber end is located at the outer edge of the aggregate cluster. The interior of the aggregate cluster is substantially free of thermoplastic binder fiber ends. The macro absorbent structure includes thermoplastic binder long fibers, superabsorbent particles bound to the thermoplastic binder long fibers, and staple fibers bound to the thermoplastic binder long fibers. In these embodiments, the aggregate cluster comprises superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster, staple fibers bound to the thermoplastic binder fibers in the aggregate cluster, or superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster. It can include both staple fibers.

In other embodiments, the absorbent structure includes a macro absorbent structure. The macro absorbent structure includes a plurality of aggregate clusters intermixed within the macro absorbent structure. The aggregate cluster has a thermoplastic binder fiber having an outer edge and an inside and having thermoplastic binder fiber ends. The thermoplastic binder fiber end is located at the outer edge of the aggregate cluster. The interior of the aggregate cluster is substantially free of thermoplastic binder fiber ends. The macro absorbent structure includes staple fibers and superabsorbent particles intermixed with the staple fibers. In these embodiments, the aggregate cluster comprises superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster, staple fibers bound to the thermoplastic binder fibers in the aggregate cluster, or superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster. It can include both staple fibers.

In various embodiments, the aggregate cluster can have a maximum size of 0.5 mm to 20 mm and / or a weight percent of 20 to 50%. In various embodiments, the thermoplastic binder long fibers are elastic.

In one embodiment, the stabilized absorbent structure comprises 5-50% by weight of meltblown polyolefin binder fibers having an average fiber length greater than 1 cm. In addition, the stabilized absorbent structure comprises 1 to 50% by weight of cellulose fibers bound within the polyolefin binder fibers. The stabilized absorbent structure also includes 30 to 90 weight percent of superabsorbent particles bound in the polyolefin binder fibers. In addition, the stabilized absorbent structure comprises from 1 to 50% by weight of aggregate clusters. Each aggregate cluster has an outer edge and an inner one. The aggregate cluster comprises meltblown polyolefin binder fibers having meltblown polyolefin binder fiber ends. The aggregate cluster further includes cellulose fibers bound to the polyolefin binder fibers in the aggregate cluster. The aggregate cluster further includes superabsorbent particles bound to the polyolefin binder fibers in the aggregate cluster. The meltblown polyolefin binder fiber ends are located at the outer edge of the aggregate cluster. The interior of the aggregate cluster is substantially free of meltblown polyolefin binder fiber ends.

In another embodiment, the present invention provides a method of making a stabilized absorbent structure. Such a method includes providing a first absorbent structure. The first absorbent structure includes thermoplastic binder long fibers. The method further includes dividing the first absorbent structure into aggregate clusters. The aggregate cluster is provided as a stream of aggregate clusters. The method includes providing a stream of extrusion melted thermoplastic polymer fibers. The aggregate cluster stream and the polymer fiber stream are integrated into a single product stream. A single product stream is collected on the forming surface to produce a second stabilized absorbent structure comprising aggregate clusters. In various embodiments, a second stabilized absorbent structure comprising aggregate clusters can be used to create a disposable absorbent article.

In various embodiments, the method further comprises incorporating the stream of superabsorbent particles into an aggregate cluster stream, a polymer fiber stream, or a single product stream.

In various embodiments, the method further comprises integrating the stream of wood pulp fibers into an aggregate cluster stream, a polymer fiber stream, or a single product stream.

1 shows a representative example of a schematic diagram of an exemplary absorbent article of the present invention.

2A shows a representative example of a cross-sectional view of a first alternative embodiment of the absorbent article of FIG. 1 taken along line 2-2.

2B shows a representative example of a cross-sectional view of a second alternative embodiment of the absorbent article of FIG. 1 taken along line 2-2.

3A shows an optical microscope image of an example macro absorbent structure comprising aggregate clusters according to the present invention.

FIG. 3B shows a scanning electron micrograph image of a portion of the example macro absorbent structure of FIG. 3A.

4 shows a scanning electron micrograph image of an exemplary aggregate cluster according to the present invention.

4A shows a scanning electron micrograph image of the cut thermoplastic binder fiber ends.

5 shows a scanning electron micrograph image of an exemplary aggregate cluster according to the present invention.

6A shows a representative example of an embodiment of the aggregate cluster according to the present invention.

6B shows a representative example of another embodiment of an aggregate cluster according to the present invention.

6C shows representative examples of further embodiments of aggregate clusters according to the present invention.

7 shows a partial side exploded view of a method and apparatus for producing an absorbent structure of the present invention.

In one embodiment, the absorbent structure according to the present invention is suitable for absorbing a number of liquids such as water, saline and synthetic urine and body fluids such as urine, menstrual secretions and blood, and are disposable absorbent products such as diapers, adult and young. Incontinence garments and pads, bed pads; Menstrual devices such as sanitary napkins, interlabial pads and tampons; And other disposable absorbent products, such as wipes, bibs, wound dressings, and surgical capes or drapes. For illustrative purposes, the absorbent structure of the present invention is intended to be used in disposable diapers. However, those skilled in the art will recognize many other uses that can be used for such structures.

Absorbent structures of the present invention generally include macro structures and micro structures. The microstructures comprise a plurality of aggregate clusters that form parts of the macrostructures. The macrostructure includes aggregate clusters and may further include one or more from staple fibers, thermoplastic long fibers, superabsorbent materials, and the like.

As used herein, the term "fiber" or "fibrous" refers to a particulate material having a ratio of length to diameter of such particulate material of greater than about 10. In contrast, "non-fibrous" or "non-fibrous" material refers to a particulate material having a ratio of length to diameter of such particulate material of about 10 or less.

As used herein, the term "virgin" refers to a material or fiber that is first introduced into a manufacturing process. The term "virgin" excludes "recycled" or "recycled" fibers or materials. As used herein, the terms "recycle" or "recycle" are those that have been previously introduced into a manufacturing process, separated for defects or other reasons, and reintroduced into a manufacturing process and / or a second manufacturing process. It refers to a fiber, particle, aggregate or material. The recycled material may be treated as an additional process prior to re-entry into the manufacturing process or the recycled material may be added to the manufacturing process under conditions that remove it.

As used herein, the term “wetability” refers to a fiber that represents a liquid (eg water, synthetic urine or 0.9 wt% saline aqueous solution) having an air contact angle of less than 90 °. As used herein, contact angles are described, for example, in Robert J. Good and Robert J. Stromberg, Ed., In "Surface and Colloid Science-Experimental Methods", Vol. 11, (Plenum Press, 1979). Wettable fibers are appropriate to refer to fibers that exhibit a 0.9 wt% aqueous saline solution with a temperature of about 0 ° C. to about 100 ° C. and suitably ambient conditions, such as about 23 ° C., with an air contact angle of less than 90 °.

As used herein, the term “staple fiber” refers to, for example, length or natural fiber cut from the filament produced. Such staple fibers are intended to act in the absorbent structure of the present invention as a temporary reservoir for liquid and as a conduit for liquid distribution.

The staple fibers used in the absorbent structure herein may suitably have a length of about 0.5 mm to about 20 mm, more preferably about 1 mm to about 15 mm. In certain embodiments, the staple fibers can be 3 mm to 6 mm long. In certain embodiments, the staple fiber can be 1 to 2 mm. Staple fibers of this size are characterized by helping to impart desirable bulk, liquid collection, liquid distribution and strength characteristics and / or desirable flexibility and elastic properties to the absorbent structure of the present invention.

Various staple fiber materials can be used in the absorbent structures described herein. Staple fibers useful in the present invention may be formed from natural or thermoplastic materials and may include cellulose fibers such as wood pulp fibers and modified cellulose fibers, textile fibers such as cotton or rayon and substantially nonabsorbent thermoplastic polymer fibers.

For reasons of availability and price, cellulose fibers are often preferred for use as staple fiber components of the absorbent structures of the present invention, for example wood pulp fibers. However, other cellulose fiber materials such as cotton fibers can be used as staple fibers.

Another preferred type of staple fiber useful herein includes substantially nonabsorbable, crimped thermoplastic polymer fibers. Each fiber of this type is almost non-absorbent in nature and on its own. Thus, such fibers must be produced from thermoplastic polymeric materials that do not substantially expand or form gels in the presence of liquids typically encountered in disposable absorbent products, such as urine or physiological secretions. Examples of suitable polymeric materials that can be used to make staple fibers include polyesters, polyolefins, polyacryl, polyamides, polystyrenes, and the like. In certain embodiments, staple fibers are produced from polyethylene, polypropylene or polyethylene terephthalate.

In addition, the staple fibers used in the present invention can be crimped so that the resulting absorbent structures have agglomeration resistance and predetermined elasticity during use in absorbent articles. The crimped staple fiber is one that has continuous wavy, curved or serrated features along its length. Fiber crimps of this type are described in detail in US Pat. No. 4,118,531 to Hauser, issued October 3, 1978, which is incorporated herein by reference.

Suitable wettable fibers may be formed essentially of wettable fibers or may be formed of essentially hydrophobic fibers that have undergone a surface treatment that makes the fibers hydrophilic. In the case of using the surface treated fibers, the surface treatment is preferably not easily changed. That is, the surface treatment preferably prevents the surface of the fiber from being washed away by the first liquid attack or contact. For the present application, the surface treatment in hydrophobic polymers is generally considered not to change easily when the liquid shows an air contact angle of less than 90 ° for three consecutive contact angle measurements while drying between each measurement. In other words, if the same fiber is subjected to three separate contact angle measurements, and all three contact angle measurements show the contact angle of the liquid in the air of less than 90 °, the surface treatment on the fiber is considered not to be easily changed. If the surface treatment is easily altered, the surface treatment tends to be washed away from the fiber during the first contact angle measurement, thereby exposing the hydrophobic surface of the underlying fiber, with subsequent contact angle measurements exceeding 90 °.

The wettable staple fibers are preferably present in the elastomeric absorbent structure of the invention as wettable staple fibers in an amount of 0 to about 80 weight percent, suitably about 1 to about 50 weight percent, more suitably about 10 to about 40 weight percent. Do. "% By weight" is based on the total weight of material present. For example, a 60 g mixture consisting of 10 g of substance X, 20 g of substance Y and 30 g of substance Z comprises 16.7% by weight of X, 33.3% by weight of Y and 50% by weight of Z.

It has been found that by including thermoplastic binder fibers in the absorbent structure, the properties of the absorbent structure can be substantially improved compared to nearly identical absorbent structures that do not include thermoplastic binder fibers. As used herein, the term "thermoplastic binder fiber" is meant to describe a material that softens upon exposure to heat and substantially recovers to its initial state upon cooling to room temperature. By thermoplastic binder fibers in the softened state is meant to capture, constrain or entangle or conform to these fibers or particles adjacent to the thermoplastic binder fibers to stabilize the absorbent structure.

As used herein, the term "constraining" means that staple fibers and / or aggregate clusters and / or superabsorbent particles and / or other components are substantially moved or moved within or without the web structure. It refers to substantially immobilized staple fibers and / or aggregate clusters and / or superabsorbent particles such that they are not free. Such restraint can be achieved, for example, by intertwining the thermoplastic fibers of the web structure or by autogenous bonding, thermal deformation, capture. Thermoplastic binder fibers can be elastic or inelastic.

Thermoplastic binder fibers can be long or short fibers. As used herein, the term "long fiber" means a fiber that is greater than 6 mm. In certain embodiments, the long fibers can be greater than 1 cm, greater than 2.5 cm, greater than 50 cm, or greater than 100 cm. In certain embodiments, the thermoplastic binder long fibers can be substantially continuous filaments or fibers. As used herein, the term “substantially continuous” or “substantially continuously formed” includes spunbonded and meltblown fibers that are not cut from their initial length prior to being formed into a nonwoven web or fabric ( But not limited to) refers to a filament or fiber produced by extrusion from a spinneret. Substantially continuous filaments or fibers may be from about 15 cm to more than 1 m in length; It is formed to a length greater than the length of the nonwoven web or fabric. The definition of “substantially continuous filament or fiber” was not cut before being formed into a nonwoven web or fabric, but after forming the nonwoven web, article or fabric, for example, cutting the absorbent article into individual product units or clustering aggregates. It includes cut fibers as in the case of dividing. As used herein, the term "short fibers" generally means less than about 6 mm.

As used herein, the terms "elastic" and "elastomer" are generally used interchangeably to mean a material that is capable of restoring its initial form after deformation when the strain is removed. Specifically, as used herein, an elastic or elastomer is capable of stretching a stretched deflected length such that upon application of a biasing force the material is at least about 125% of its relaxed unbiased length, i.e., about 1.25 times, wherein the material is stretched, extended It is the nature of any material to allow at least 40% of its extension to be recovered upon relaxation of the force. An example hypothesis that satisfies this definition of elastomeric material is a 10 cm sample of material that can extend beyond 12.5 cm and recover to a length of 11.5 cm or less upon extension and relaxation to 12.5 cm. Many elastic materials can be stretched much larger than 25% of their relaxed length, and the plurality of elastic materials are restored to their initial relaxed length substantially upon stretching, stretching. The latter type of such materials is generally advantageous for the present invention.

The term "recovery" relates to contraction of the stretched material at the end of the biasing force after stretching of the material by the application of the biasing force. For example, when a material with a 10 cm relaxed unbiased length is stretched 50% by a length of 15 cm, the material is 50% elongated and has a stretched length that is 150% of its relaxed length. When this example stretched material is retracted, that is, restored to a length of 11 cm after relaxation of the strain and the stretching force, the material recovers 80% (4 cm) of its extension.

Examples of materials suitable for use in producing the thermoplastic elastomer binder fibers include diblock, triblock or multiblock elastomer copolymers such as olefin copolymers such as styrene-isoprene-styrene, styrene-butadiene-styrene, styrene-ethylene / butyl Styrene-styrene or styrene-ethylene / propylene-styrene, such as those obtained under the trade name KRATON elastomer resin from Shell Chemical Company; Polyurethanes such as those obtained under the trade name LYCRA from Invista Corporation, Wichita, Kansas, USA; Polyamides such as polyether block amides available under the tradename PEBAX polyether block amides from Ato Chemical Company; Polyesters such as E. children. Obtained under the tradename HYTREL polyester from DuPont de Nemua's Company; Or low molecular weight metallocene polyolefins such as those obtained under the trade name VISTAMAXX from ExxonMobil Chemical Company, Houston, Texas.

Many block copolymers can be used to produce thermoplastic elastomer binder fibers useful in the present invention. Such block copolymers generally comprise an elastomeric midblock portion and a thermoplastic endblock portion. Block copolymers and methods suitable for synthesizing the above are described in U.S. Pat.No. 5,645,542, issued July 8, 1997 to Anjur et al., And U.S. Pat.No. 6,362,389, issued March 26, 2002 to McDowall et al.), both of which are incorporated herein by reference.

Examples of materials suitable for use in producing inelastic thermoplastic binder fibers include polyolefins such as polypropylene and polyethylene, polyamides and polyesters such as polyethylene tetraphthalate and the like. Other suitable thermoplastic polymers are described in US Pat. No. 4,100,324, issued July 11, 1978, which is intended to be incorporated herein by reference.

Thermoplastic binder fibers may generally be formed from any thermoplastic composition capable of extruding into fibers. Thermoplastic binder fibers suitable for the present invention include meltblown fibers. Such meltblown fibers are typically very fine fibers produced by extruding a liquefied or molten fiber forming copolymer into a high velocity gaseous stream through an orifice in a die. The fibers are tapered by the gaseous stream and then solidified. For example, the resulting stream of solidified thermoplastic fibers can be collected as a cohesive fibrous mass entangled on a screen disposed in the gaseous stream. Such entangled fibrous mass is characterized in that the absorbent structure stabilized by the extreme entanglement of the fiber is produced. This entanglement imparts cohesion and strength to the resulting web structure. For example, the dry strength of such a structure, as measured by the tensile strength test described in Example 4 of US Publication No. 2004 / 0122394A1 (Fell et al.), Issued June 24, 2004, is 6 N /. 50 mm or more, wet strength is 2 N / 50 mm or more, and this document is intended to be cited herein as an incompatible document.

Such entanglement also selects the web structure to constrain or capture wettable staple fibers, aggregate clusters, superabsorbent particles, or other components during or after the formation of the web structure. Thermoplastic fibers are generally sufficiently intertwined, making it difficult, if not impossible, to remove one complete fiber from the mass of the fiber or track one fiber from start to finish.

The thermoplastic binder fibers used in the present invention may be circular in cross section, but may also be of other cross-sectional geometries, such as oval, rectangular, triangular, irregular or plural lobes. The thermoplastic binder fiber is suitably wettable. Thermoplastic binder fibers may first be produced by thermoplastic binder fibers and then subjected to hydrophilic surface treatment on the fibers to become lubricable.

Alternatively, the thermoplastic binder fibers can be made wettable by adding a hydrophilic component to the polymer prior to spinning. Generally, any polymer component that can be polymerized into a thermoplastic component that can be hydrophilized to make it wettable by hydrophilizing the resulting copolymer material, wherein the hydrophilic component does not substantially affect the properties of the resulting fiber Suitable for use on Examples of suitable hydrophilized polymer components for use in the present invention include, but are not limited to, polyethylene oxide or polyvinyl alcohol, as well as various commercially available hydrophilic surfactants.

Therefore, the thermoplastic binder fibers are preferably present in the absorbent structure of the present invention in an amount of about 1 to about 80% by weight, about 10 to about 50% by weight, and about 15 to about 30% by weight, and all weight% are absorbent structures. It is based on the total weight of. Thermoplastic binder fibers may generally be greater than about 1 cm, greater than about 10 cm, greater than about 50 cm, or may be substantially continuous. The thermoplastic binder fiber may have an average diameter of less than about 100 microns, may be less than about 50 microns, or may be about 30 microns.

In various embodiments, the absorbent structure can include a superabsorbent material, such as a hydrogel forming polymer material. The incorporation of the hydrogel forming polymer material into the absorbent structure allows for the use of less wettable staple fibers, which generally have a higher liquid absorbency based on g per gram than the wettable staple fibers. . In addition, the hydrogel forming polymer material is generally less pressure sensitive than wettable staple fibers. Thus, the use of hydrogel forming polymeric materials generally enables the manufacture and use of smaller, thinner disposable absorbent articles. Thus, the absorbent structure of the present invention may optionally include a hydrogel forming polymer material in macrostructures, microstructures, or both.

As used herein, “hydrogel forming polymer material” means to refer to a high absorbent material commonly referred to as a superabsorbent material. Such high absorbent materials generally contain a predetermined amount of liquid, such as synthetic urine, 0.9% aqueous saline solution or body fluid, such as menstrual discharge, urine or blood, about 10 times the weight of the superabsorbent material under conditions where superabsorbent material is used. As mentioned above, it can absorb suitably up to about 20 to about 100 times. Examples of typical conditions include temperatures of about 0 ° C. to about 100 ° C. and suitably ambient conditions such as about 23 ° C. and relative humidity of about 30 to about 60% and the like. Upon absorption of the liquid, the superabsorbent material typically swells and forms a hydrogel.

The hydrogel forming polymer material may be formed from polyacrylate hydrogel polymers, as well as organic hydrogel materials, which may include natural materials such as agar, pectin and guar gum. Suitable hydrogels are described in US Pat. No. 5,645,542 to Anjur et al., Issued July 8, 1997, which is incorporated herein by reference in its entirety. Suitable hydrogel forming materials also include FAVOR SXM-880 provided by Degusa Superupzobers, Greensboro, North Carolina, USA, and HYSORB 8800AD provided by BASF, Charlotte, North Carolina.

Suitably, the hydrogel forming polymer material has a maximum cross-sectional diameter of about 50 μm to about 1,000 in the unexpanded state as measured by sieve analysis by the American Society for Testing and Materials (ASTM) Test Method D-1921. In the form of particles which are preferably from about 100 μm to about 800 μm. Particles of the hydrogel-forming polymeric material included within the aforementioned ranges may be solid particles, porous particles or may be aggregated particles comprising a plurality of smaller particles aggregated into particles included within the aforementioned size ranges. It should be understood that.

The hydrogel forming polymer material may additionally or alternatively include a "coated" superabsorbent as described in US Pat. No. 6,387,749 (Reeves et al.), Issued May 14, 2002, which documents Reference is made herein to the contrary literatures.

The hydrogel forming polymer material is in an amount of about 0 to 90% by weight, suitably in an amount of about 20 to about 85% by weight, more suitably about 30 to about 80% by weight, based on the total weight of the absorbent structure. It is advantageous to be present in the absorbent structure in the content of.

It has been found that by including aggregate clusters in the absorbent structure, the properties of the absorbent structure can be maintained or improved at lower yields of manufacturing costs compared to nearly identical absorbent structures that do not include aggregate clusters. While suitable for a wide range of absorbent articles, the absorbent structures of the present invention are intended to be described with disposable diapers for purposes of illustration.

Referring to FIG. 1, a disposable diaper is shown generally at 26. The diaper 26 includes a top sheet 28, a back sheet 30, and an absorbent structure 10 disposed between the top sheet 28 and the back sheet 30. 2A and 2B show cross-sections of another example disposable diaper of FIG. 1 taken along line 2-2. The disposable diaper 26 of FIG. 2A includes a macroabsorbent structure 10 that includes a long or substantially continuous thermoplastic binder fiber 12, staple fibers 14, superabsorbent particles 16, and aggregate clusters 18. To illustrate. In various embodiments, the macro absorbent structure may comprise thermoplastic binder long fibers, superabsorbent particles, and aggregate clusters, but do not include staple fibers outside of the aggregate clusters. In various embodiments, the macro absorbent structure may comprise long or substantially continuous thermoplastic binder fibers, staple fibers, aggregate clusters, but do not include superabsorbent particles outside of the aggregate clusters. In various embodiments, the macro absorbent structure may comprise long or substantially continuous thermoplastic binder fibers and aggregate clusters, but do not include superabsorbent particles or staple fibers outside of the aggregate clusters.

Disposable diaper 26 in FIG. 2B shows another exemplary macro absorbent structure 10 that includes staple fibers 14, superabsorbent particles 16, and aggregate clusters 18. In various embodiments, the macro absorbent structure may comprise only staple fibers and aggregate clusters in the macro absorbent structure.

As used herein, the term “aggregate cluster” is a collection of units into masses, generally having a maximum size of generally less than 2 cm, forming discontinuous portions of the macro absorbent structure, having an outer margin and an interior. The interior of the aggregate cluster contains superabsorbent particles, staple fibers, or both, which are substantially free of thermoplastic binder fiber ends and are bound to thermoplastic binder fibers, while being held together by thermoplastic binder fibers having thermoplastic binder fiber ends at the outer edges. And to a structure that does not require additional bonding, crosslinking polymerization, adhesion or linking agents to maintain the structure.

In various embodiments, aggregate clusters may further include crosslinked polymerization, adhesives, linking agents, and the like, but such additional elements need not maintain the physical structure of the aggregate clusters.

As used herein, the term "end" or "ends" refers to the extreme or distal portion of a fiber. The fibers may comprise natural ends, such as present in cellulose fibers, cotton fibers, and the like, or the fibers may have ends mechanically formed by, for example, cutting, grinding, crushing, pinching, nipping, and the like.

As used herein, the term "external edge" refers to the outer boundary or surface of a body, such as an aggregate cluster. As used herein, the term "inner" refers to a volume partitioned by an outer edge.

As used herein, the term "substantially free of ends" means having up to five thermoplastic binder fiber ends visible inside the aggregate cluster. One way of determining whether substantially no end is present in the thermoplastic binder fibers inside the aggregate cluster is to use scanning electron microscopy (SEM) or equivalent equipment. A suitable SEM is model JSM-840, available from Zeol USA Inc., Peabody, Massachusetts.

3A is an optical micrograph generated using the brand name NIKON Digital Camera Model 8700. The image generally uses light transmitted through a portion of the macro absorbent structure shown at 10. The image is generated at 4 magnifications. Darker areas are aggregate clusters, generally indicated by arrows. Two aggregate clusters were distinguished as (1) and (2).

3B shows an image from an SEM of a portion of the macro absorbent structure of FIG. 3A. The aggregate clusters 1 and 2 located in the macro absorbent structure 10 are generally indicated by dashed lines for illustration.

4 shows an image from the SEM of an exemplary aggregate cluster according to the invention, shown generally at 18. The aggregate cluster 18 has an outer edge 62 and an interior. The aggregate cluster 18 is manually removed from the absorbent structure including the aggregate cluster 18 for inspection to minimize any disruption to the aggregate cluster structure. The outer edge 62 can be irradiated at various magnifications to look at the thermoplastic binder fiber ends 60. For example, the thermoplastic binder fiber end 60 may be shown at 150 times magnification in FIG. 4A.

FIG. 5 shows an SEM image of the exemplary aggregate cluster shown generally at 18 by the present invention manipulated using a small probe to expose the interior 64. The interior 64 can be irradiated at various magnifications to confirm that there is substantially no thermoplastic binder fiber end in the interior 64.

As an alternative to SEM images, three-dimensional visualization and measurement techniques, such as microcomputer tomography, can be used to nondestructively view structures. The instrument is suitably the SkyScan-1072 available from Skyscan, Artsella, Belgium. The software is suitably Voxblast (TM) 3D visualization and measurement software available from Vatech, Fairfield, Iowa.

Exemplary aggregate clusters 18 according to the present invention are shown representatively in FIGS. 6A, 6B and 6C. In FIG. 6A, one or more thermoplastic binder fibers 20 may confine or capture one or more staple fibers 22 and one or more superabsorbent particles 24 to form aggregate clusters 18. The aggregate cluster 18 generally has an outer edge 62 and an interior 64, shown for purposes of illustration using dashed lines. The thermoplastic binder fiber 20 has a thermoplastic binder fiber end 60 formed when the aggregate cluster 18 is divided from the stabilized absorbent structure. The thermoplastic binder fiber end 60 is located at the outer edge 62 of the aggregate cluster 18, while the interior 64 of the aggregate cluster 18 is substantially free of the thermoplastic binder fiber end 60. Conversely, staple fibers 22 may be cut, crushed or broken during formation of aggregate clusters 18 to form staple fiber ends 66, while interior 64 of aggregate clusters 18 are generally thermoplastic binder fibers. Unlike the end 60, it includes a number of staple fiber ends 66.

6B shows another example of aggregate cluster 18. In FIG. 6B, the aggregate cluster 18 comprises thermoplastic binder fibers 20 and staple fibers 22 constrained or trapped within the thermoplastic binder fibers 20. The thermoplastic binder fiber 20 has a thermoplastic binder fiber end 60 at the outer edge 62 of the aggregate cluster 18. The interior 64 of the aggregate cluster 18 is substantially free of thermoplastic binder fiber ends 60. Staple fibers 22 have staple fiber ends 66 at both the inner 64 and outer edge 62 of the aggregate cluster 18.

6C shows another example of aggregate cluster 18. In FIG. 6C, aggregate cluster 18 includes thermoplastic binder fibers 20 and superabsorbent particles 24 constrained or entrapped in the thermoplastic binder fibers 20. The thermoplastic binder fiber 20 has a thermoplastic binder fiber end 60 at the outer edge 62 of the aggregate cluster 18. The interior 64 of the aggregate cluster 18 is substantially free of thermoplastic binder fiber ends 60. Superabsorbent particles 24 may be at least partially located at the outer edge 62 of the aggregate cluster 18, the interior 64 of the aggregate cluster 18, or both.

Typically, aggregate clusters are formed by dividing a stabilized absorbent structure comprising substantially continuous thermoplastic binder fibers into discrete units of various sizes. Splitting a stabilized absorbent structure can be accomplished by grinding, grinding, cutting, dissociating, shocking, breaking, or otherwise breaking down from the stabilized absorbent composite. Stabilized absorbent composites used to produce aggregate clusters may be stabilized absorbent composites specifically produced to produce aggregate clusters, or may be waste materials, trimming materials or recycled products.

Once the aggregate cluster is created, it is put into the absorbent manufacturing process along with the virgin material to form the macro absorbent structure of the absorbent article. The aggregate clusters described herein maintain a structure similar to the macrocomposite structures in which aggregate clusters are formed, due to the inherently high integrity of the source absorbent material. The high integrity of the source absorbent material is at least in part due to the long or substantially continuously formed thermoplastic binder fibers that constrain, capture or entangle other components. Aggregate clusters have been found to retain most of the fluid handling performance of the initial absorbent material in which they are divided. While not wishing to be bound by any single logic, aggregate clusters are stabilized absorbent structures and various macro absorbent structures that can improve the absorbent capacity of the entire absorbent assembly, in particular due to the increased gap space created by the aggregate clusters. It has been found to produce discontinuities in the continuous fibrous structure of. This gap space can result in less restrictive expansion of the superabsorbent material outside and around the aggregate cluster. In other words, the superabsorbent material, which may be hindered by the macro absorbent structure, may be moved and expanded to an area opened by the cluster of aggregates. In addition, the use of aggregate clusters in the absorbent structure can be saved when using recycled products or trimming waste produced in the production of stabilized absorbent composites as source material.

The aggregate cluster may be divided into discrete units of various sizes. In various embodiments, the aggregate clusters may have a maximum size of less than 20 mm, less than 10 mm or less than 5 mm. In certain embodiments, the aggregate clusters may have a maximum size of 0.5 mm to 5 mm.

The absorbent structure can be in the form of a composite comprising a single integrally formed layer or multiple layers. If the absorbent structure comprises a plurality of layers, the layers are preferably in liquid communication with each other so that the liquid present in the single layer can be flowed or transported to another layer. For example, the layers can be separated by cellulose tissue wrap sheets, such as those known to those skilled in the art.

In addition, the absorbent structures of the present invention can be used or combined with other absorbent structures, and the absorbent structures of the present invention are used as separate layers or as individual zones or sites within larger composite absorbent structures. The absorbent structures of the present invention may be combined with other absorbent structures by methods known to those skilled in the art, such as by using adhesives or simply stacking various structures together, or for example holding tissue tissue sheets and composite structures together. Can be combined.

The hydrogel forming polymeric material may generally be distributed in individual layers in a uniform manner or may be present in the fibrous layer as a layer or other non-uniform distribution. Likewise, aggregate clusters may be distributed in individual layers in a general uniform manner or may be present in the fibrous layer as layers or other non-uniform distributions.

The absorbent structure of the present invention may suitably have a basis weight of about 50 g / m 2 to about 2,000 g / m 2 or about 200 g / m 2 to about 1,500 g / m 2 or about 300 g / m 2 to about 1,000 g / M 2. For example, pantyliners require a lower basis weight (about 100 g / m 2) than diapers (about 700 g / m 2).

The absorbent structure of the present invention suitably has a density from about 0.03 g / dL to about 0.5 g / dL or from about 0.05 g / dL to about 0.45 g / dL or from about 0.08 g / dL to about 0.4 g / dL. In certain embodiments, the density may be between 0.12 g / dl and 0.32 g / dl.

In certain embodiments, the macro absorbent structure may comprise long or substantially continuous thermoplastic binder fibers, wettable staple fibers, superabsorbent particles, a plurality of aggregate clusters or combinations thereof. Aggregate clusters may include thermoplastic binder fibers, staple fibers, superabsorbent particles, and combinations thereof. The thermoplastic binder fibers in the aggregate cluster may have thermoplastic binder fiber ends located on the outer edge of the aggregate cluster, but there may be substantially no thermoplastic binder fiber ends inside the aggregate cluster. In various embodiments, the wettable staple fibers of the macro absorbent structure and / or aggregate clusters can be selected from the group consisting of cellulose fibers, woven fibers, and thermoplastic polymer fibers. In certain embodiments, the wettable staple fibers of the macro absorbent structure and / or aggregate clusters can be wood pulp fibers.

In one embodiment, the macro absorbent structure may comprise 5 to 50 weight percent meltblown polyolefin binder fibers having an average fiber length greater than 1 cm. The macro absorbent structure may further comprise 0-50% by weight of cellulose fiber bound or entrapped in the polyolefin binder fiber. The macro absorbent structure may further comprise 30 to 90 weight percent of superabsorbent particles bound or entrapped in the polyolefin binder fiber. The macro absorbent structure may further comprise 1 to 50% by weight of aggregate clusters. The aggregate cluster may comprise meltblown polyolefin binder fibers having meltblown binder fiber ends located on the outer edge of the aggregate cluster, although there may be substantially no meltblown binder fiber ends inside the aggregate cluster. In other embodiments, the aggregate cluster may comprise meltblown polyolefin binder fibers having a fiber length greater than 5 mm.

Fiber length can be measured by known optical imaging techniques, including scanning electron micrographs or other methods. This may apply to macro absorbent structures or aggregate clusters. Inspection of the interior of the aggregate cluster may require the destruction of the structure by manipulating the aggregate cluster with a small probe. Alternatively, as described above, three-dimensional visualization and measurement techniques such as microcomputer tomography can be used to non-destructively see the structure.

In one embodiment, the macro absorbent structure may comprise 5 to 50 weight percent of meltblown polyolefin binder fibers having an average fiber length greater than 1 cm. The macro absorbent structure may further comprise 0-50% by weight of cellulose fiber bound or entrapped in the polyolefin binder fiber. The macro absorbent structure may further comprise 30 to 90 weight percent of superabsorbent particles bound or entrapped in the polyolefin binder fiber. The macro absorbent structure may further comprise 1 to 50% by weight of aggregate clusters. The aggregate cluster may comprise continuously formed meltblown polyolefin binder fibers. Aggregate clusters may be produced by dividing a stabilized absorbent structure formed partially by continuous meltblown binder fibers. The method of dividing the stabilized absorbent material, the source absorbent material, produces a polyolefin binder fiber end located at the outer edge of the aggregate cluster.

In addition, in various embodiments, the aggregate cluster may further comprise cellulose fibers constrained or captured in the meltblown polyolefin binder long fibers in the aggregate cluster. The aggregate cluster may further comprise superabsorbent particles constrained or trapped in the meltblown polyolefin binder fibers in the aggregate cluster.

In another embodiment, the macro absorbent structure may comprise 10 to 40 weight percent of meltblown polyolefin binder fibers having an average fiber length greater than 1 cm. The macro absorbent structure may further comprise 40 to 80 weight percent of cellulose fibers bound or entrapped in the polyolefin binder fibers. The macro absorbent structure may further comprise 0-20% by weight of superabsorbent particles bound or entrapped in the polyolefin binder fiber. The macro absorbent structure may further comprise 1 to 50% by weight of aggregate clusters. The aggregate cluster may comprise meltblown polyolefin binder fibers having a fiber length greater than 1 cm or greater than 5 mm. The meltblown polyolefin binder fibers of the aggregate cluster may include meltblown polyolefin binder fiber ends located on the outer edge of the aggregate cluster. The interior of the aggregate cluster is substantially free of meltblown polyolefin binder fiber ends. In addition, the aggregate cluster may include cellulose fibers bound or entrapped in the polyolefin binder fibers in the aggregate cluster. The aggregate cluster may further comprise superabsorbent particles bound or trapped by the polyolefin binder fibers in the aggregate cluster.

In another embodiment, the macro absorbent structure can include thermoplastic binder short fibers, wettable staple fibers, superabsorbent particles, and a plurality of aggregate clusters. The aggregate cluster may comprise wettable staple fibers and thermoplastic binder fibers that bind or capture the superabsorbent particles. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, while the interior of the aggregate cluster is substantially free of the thermoplastic binder fiber end.

In another embodiment, the macro absorbent structure can include wettable staple fibers, superabsorbent particles, and a plurality of aggregate clusters. Aggregate clusters may comprise cellulose fibers and thermoplastic binder fibers that bind or capture the superabsorbent particles. The thermoplastic binder fibers in the aggregate cluster include thermoplastic binder fiber ends located on the outer edge of the aggregate cluster, while the interior of the aggregate cluster is substantially free of thermoplastic binder fiber ends.

In another embodiment, the macro absorbent structure may comprise long or substantially continuous thermoplastic binder fibers, wettable staple fibers, superabsorbent particles, and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and wettable staple fibers bound or entrapped in the thermoplastic binder fibers. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, while the interior of the aggregate cluster is substantially free of the thermoplastic binder fiber end.

In another embodiment, the macro absorbent structure can include substantially continuous thermoplastic binder fibers, superabsorbent particles, and a plurality of aggregate clusters that confine or capture the wettable staple fibers. The aggregate cluster may comprise thermoplastic binder fibers and superabsorbent particles constrained or entrapped in the thermoplastic binder fibers. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, while the interior of the aggregate cluster is substantially free of the thermoplastic binder fiber end.

In another embodiment, the macro absorbent structure can include wettable staple fibers, superabsorbent particles, and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and wettable staple fibers constrained or trapped within the thermoplastic binder fibers. The thermoplastic binder fiber of the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure can include thermoplastic binder short fibers, wettable staple fibers, superabsorbent particles, and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and cellulose fibers constrained or entrapped in the thermoplastic binder fibers. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure can include wettable staple fibers, superabsorbent particles, and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and superabsorbent particles constrained or entrapped in the thermoplastic binder fibers. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure can include thermoplastic binder short fibers, wettable staple fibers, superabsorbent particles, and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and superabsorbent particles constrained or entrapped in the thermoplastic binder fibers. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure can include substantially continuous thermoplastic binder fibers, superabsorbent particles, and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and superabsorbent particles constrained or entrapped in the thermoplastic binder fibers. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure can include substantially continuous thermoplastic binder fibers, wettable staple fibers, and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and wettable staple fibers constrained or trapped within the thermoplastic binder fibers. The thermoplastic binder fiber of the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure can include substantially continuous thermoplastic binder fibers and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and wettable staple fibers constrained or trapped within the thermoplastic binder fibers. The thermoplastic binder fiber of the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure can include substantially continuous thermoplastic binder fibers and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers and superabsorbent particles constrained or entrapped in the thermoplastic binder fibers. The thermoplastic binder fiber of the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure can include substantially continuous thermoplastic binder fibers and a plurality of aggregate clusters. The aggregate cluster may comprise thermoplastic binder fibers, wettable staple fibers constrained or entrapped in the thermoplastic binder fibers, and superabsorbent particles constrained or entrapped in the thermoplastic binder fibers. The thermoplastic binder fiber of the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure includes thermoplastic binder short fibers, wettable staple fibers and a plurality of aggregate clusters. The aggregate clusters comprise thermoplastic binder fibers. The aggregate cluster further includes superabsorbent particles constrained or trapped in the thermoplastic binder fibers, staple fibers constrained or trapped in the thermoplastic binder fibers or both. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure includes thermoplastic binder short fibers, superabsorbent particles, and a plurality of aggregate clusters. The aggregate clusters comprise thermoplastic binder fibers. The aggregate cluster further includes superabsorbent particles constrained or trapped in the thermoplastic binder fibers, staple fibers constrained or trapped in the thermoplastic binder fibers or both. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure includes thermoplastic binder short fibers and a plurality of aggregate clusters. The aggregate clusters comprise thermoplastic binder fibers. Aggregate clusters include superabsorbent particles constrained or entrapped in thermoplastic binder fibers, staple fibers constrained or entrapped in thermoplastic binder fibers or both. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In another embodiment, the macro absorbent structure may comprise wettable staple fibers and a plurality of aggregate clusters. The aggregate clusters comprise thermoplastic binder fibers. The aggregate cluster further includes superabsorbent particles constrained or trapped in the thermoplastic binder fibers, staple fibers constrained or trapped in the thermoplastic binder fibers or both. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

In embodiments comprising substantially continuous thermoplastic binder fibers in the macro absorbent structure and thermoplastic binder fibers in the aggregate cluster, the substantially continuous thermoplastic binder fibers of the macro absorbent structure have a composition substantially the same as the thermoplastic binder fibers of the aggregate cluster. Can be. In addition, in embodiments comprising staple fibers in the macro absorbent structure and the aggregate cluster, the staple fibers of the macro absorbent structure can have a composition that is nearly identical to the staple fibers of the aggregate cluster. Likewise, in embodiments comprising superabsorbent particles and aggregate clusters of the macroabsorbent structure, the superabsorbent particles of the macroabsorbent structure may have a composition substantially the same as the superabsorbent particles of the aggregate cluster.

In embodiments comprising substantially continuous thermoplastic binder fibers in the macro absorbent structure and thermoplastic binder fibers in the aggregate cluster, the substantially continuous thermoplastic binder fibers of the macro absorbent structure have a different composition than the thermoplastic binder fibers of the aggregate cluster. Can be. In addition, in embodiments comprising staple fibers and aggregate clusters in the macro absorbent structure, the staple fibers of the macro absorbent structure may have a different composition than the staple fibers of the aggregate clusters. Likewise, in embodiments comprising superabsorbent particles and aggregate clusters in the macro absorbent structure, the superabsorbent particles of the macro absorbent structure may have a different composition than the superabsorbent particles of the aggregate cluster. In certain embodiments, the macro absorbent structure and / or aggregate cluster may comprise one or more additional types of staple fibers.

The absorbent structure of the present invention may include other components that do not adversely affect any absorption of the absorbent structure. Examples of exemplary materials that can be used as additional ingredients include processability, liquid handling and physical or visual / tactile properties of pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, particulates, binder fibers, and absorbents of the components. Materials and / or various components added to improve the appearance may be used, but the present invention is not limited thereto.

1, disposable diaper 26 is illustrated by one embodiment of the present invention. Disposable diaper 26 includes a back sheet 30, a top sheet 28, and an absorbent structure 10 disposed between the back sheet 30 and the top sheet 28. The absorbent structure 10 is an absorbent structure according to the present invention.

Those skilled in the art will know various materials suitable for use as the top sheet and the back sheet. Examples of suitable materials for use as the top sheet include liquid permeable materials having a basis weight of about 15 to about 25 g / m 2, such as spunbonded polypropylene or polyethylene. Examples of materials suitable for use as the back sheet include impermeable materials such as polyolefin films, as well as vapor permeable materials such as microporous polyolefin films. Laminates, including woven nonwovens, are also known in the art and are suitable for use as back sheets in the present invention.

In addition, those skilled in the art will appreciate that additional components may be optionally added depending on the intended use of the diaper. For example, the diaper may include a receiving flap, leg elastics, waist elastics, fasteners, lotions and treatments, wave control layers, tissue layers, spacer layers, pit panels, and the like. These parts and others are described in Uitenbroek et al., Issued Jan. 27, 2004, which is incorporated herein by reference.

In another embodiment, the present invention is directed to a method of making an absorbent structure having wettable staple fibers, thermoplastic fibers, at least one of superabsorbent particles, aggregate clusters, and the like. The absorbent structure is in the form of a fibrous matrix. The fibrous matrix can be air-laid to form the fibrous matrix through a spunbond or meltblown process, a carding process wet-laid process, or through substantially any other means known to those skilled in the art.

Methods of incorporating wettable staple fibers and / or hydrogel forming polymeric materials into the fibrous matrix are known to those skilled in the art. Suitable methods include airlaying the fibers of the fibrous matrix and the wettable staple fibers and / or hydrogel forming polymer materials simultaneously, or forming the fibers and the wettable staple fibers and / or the hydrogel forming polymer materials of the fibrous matrix. Concurrently wetlaying to incorporate the wettable staple fibers and / or hydrogel forming polymeric material into the matrix. Alternatively, after formation of the fibrous matrix, the wettable staple fibers and / or the hydrogel forming polymeric material can be applied to the fibrous matrix. Another method involves disposing a hydrogel forming polymer material between two sheets of at least one of the two sheets of material that are fibrous and water-permeable. The hydrogel forming polymeric material may generally be uniformly disposed between two sheets of material, or may be disposed in discrete pockets formed of two sheets. The wettable staple fibers are generally preferably uniformly distributed in the fibrous matrix. However, the wettable staple fibers may be unevenly distributed to achieve the desired liquid absorbency.

Methods of making stabilized absorbent structures include providing a stream comprising substantially continuous extrusion melted polymer binder fibers, such as polyolefins; Providing a stream comprising individualized staple fibers, such as wood pulp fibers; And providing a stream comprising a plurality of aggregate clusters. At least one of the streams may be integrated into a single product stream prior to collecting the contents of the stream on the forming surface to produce a stabilized absorbent structure. In various embodiments, such a method can include a carrier sheet for collecting the product stream. In various embodiments, the stabilized absorbent structure may comprise a complete mixture of wood pulp fibers and aggregate clusters incorporated by physical entrapment and mechanical entanglement in a substantially continuous polymeric binder fiber. In various embodiments, the method may further comprise a stream comprising superabsorbent particles. In certain embodiments, the superabsorbent stream and the pulp fiber stream are combined into a single stream prior to combining with the stream comprising substantially continuous extrusion melted polymer binder fibers.

The stream comprising the aggregate clusters can be introduced into the absorbent manufacturing process via air transport at several locations. A vacuum position (negative pressure) is preferred for proper mixing.

Referring to FIG. 7, a method of introducing a plurality of aggregate clusters generally involves air transporting the aggregate cluster 18 to the fiber dissociation device 32 at the feed position 34. Fiber dissociation device 32 is a commercially available device that separates each staple fiber 14, such as cellulose pulp sheet, from source sheet 36. Among them, the fiber dissociation device is a paper converting machine company in Green Bay, Wisconsin, and a cut paper in Sheboygan Pearl, Wisconsin, USA. Available from Joa Inc. and Kamas Industries Ave, Bellinge, Sweden.

The advantage of introducing the aggregate cluster 18 stream into the fiber dissociation device 32 at the input position 34 is to uniformly mix the aggregate cluster 18 with the virgin staple fibers 14. In addition, this dosing method can provide a uniform basis weight and low weight changeability in the absorbent structure 10. Adding the aggregate cluster 18 to the fiber dissociation device 32 adds significant fiber dissociation device impact energy to the superabsorbent in the aggregate cluster 18. As a result, the use of such a structure allows certain variations of the fluid handling properties of the superabsorbent to occur.

Alternatively, the aggregate cluster 18 may be introduced into the molding process after the fiber dissociation apparatus is discharged, and in the conduit duct 38, the fiber dissociation apparatus 32 is connected to the forming surface 40 shown at the feeding position 44. Let's do it. Examples of such conduit ducts include forming chambers generally made of polycarbonate, or duct tubing with electroplated helical or seamless deformation.

Many forming systems use fans 42 or other devices to generate kinetic energy for transporting staple fibers 14 to the forming surface 40. Certain molding systems place the kinetic energy device on the side of the forming surface 40 opposite the fiber dissociation device 32. Other molding systems place the kinetic energy device between the fiber dissociation device 32 and the forming surface 40. In this case, the vacuum generated by the kinetic energy device (suction unit) is a preferred position for introducing the aggregate cluster 18 into the manufacturing process. While the vacuum helps to integrate the flow of the aggregate cluster 18, the kinetic energy device assists in mixing the aggregate cluster 18 with the virgin staple fibers 14. Examples of kinetic energy devices include blower extractors, blowers and fans available from the New York Blower Company in Laport, Idaho, USA and Fox Valves, Dover, NJ.

A molding system that air transports the superabsorbent particles 16 into the molding process provides another location for introducing the aggregate cluster 18 into the process. Venturi extractor 50 may be used to apply a vacuum to draw superabsorbent 16 into delivery pipe 46. This vacuum source provides an opportunity for introducing the aggregate cluster 18 into the superabsorbent delivery system at the input location 48. The venturi extractor helps to integrate the flow of the air transported aggregate cluster 18, while the venturi extractor 50 helps to mix the aggregate cluster 18 with the virgin superabsorbent 16.

In general, in order to minimize any degradation of the fluid handling properties of the superabsorbent 24 in the aggregate cluster 18, the air transport speed of the aggregate cluster 18 into the forming process must be kept to a minimum. In order to prevent the aggregate cluster 18 from settling out of the air flow (salutation), a speed of at least 3,500 ft / min must be maintained. Thus, aggregate cluster 18 may be 3,000 to 6,000 ft / min (914.4 m / min to 1,828.8 m / min), 3,000 to 5,000 ft / min (914.4 m / min to 1,524 m / min) or 3,500 to 4,000 ft / min Air transport at a rate of (1,066.8 m / min to 1,219.2 m / min) is suitable. A method and apparatus suitable for delivering particulate material to an air stream is disclosed in U. S. Patent No. 6,461, 086 (Milanowski et al.), Issued Oct. 8, 2002, which is incorporated herein by reference. I would like to.

In another embodiment, the present invention includes a method of making an absorbent structure comprising producing a plurality of first absorbent articles in a first production line. The first absorbent article has a macrostructure comprising thermoplastic binder fibers that are substantially continuous. The macro absorbent structure may further comprise superabsorbent particles, staple fibers, aggregate clusters or combinations thereof bound or entrapped in the substantially continuous thermoplastic binder fibers of the macro absorbent structure.

The first absorbent article from the first production line can then be pulverized, crushed, cut, dissociated, shocked, or poreized or dividedly treated to produce aggregate clusters having an outer edge and an interior. The aggregate cluster comprises thermoplastic binder fibers and may include superabsorbent particles, staple fibers or both bound or trapped by the thermoplastic binder fibers in the aggregate cluster. The thermoplastic binder fiber in the aggregate cluster has a thermoplastic binder fiber end located at the outer edge of the aggregate cluster, but substantially no thermoplastic binder fiber end is present inside the aggregate cluster.

The aggregate cluster is then combined with the virgin material in a second production line to produce one or more second absorbent articles. The second absorbent article may further include, but is not limited to, thermoplastic fibers, long fibers, staple fibers, superabsorbent particles, and combinations thereof.

In various embodiments, the second production line can be the same as the first production line. Thus, at least a portion of the first absorbent article may be pore treated to form aggregate clusters, which aggregate clusters may produce more first absorbent articles further comprising aggregate clusters. In other embodiments, the second production line may produce the absorbent article by air forming, wet lay, or other absorbent article forming process known to those skilled in the art.

It is understood that the details of the absorbent core of the present invention presented for purposes of illustration should not be regarded as limiting the scope of the present invention. Those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without departing substantially from the novel teachings and advantages of the present invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims appended hereto and all equivalents thereto. It will also be appreciated that many embodiments do not achieve all of the advantages of certain embodiments, particularly preferred embodiments, and the absence of certain advantages is necessarily to mean that such embodiments are outside the scope of the present invention. It should not be interpreted.

Claims (13)

An absorbent structure comprising a macro absorbent structure, the macro absorbent structure comprising a plurality of aggregate clusters intermixed within the macro absorbent structure, the aggregate clusters comprising thermoplastic binder fibers having an outer edge and an interior and having thermoplastic binder fiber ends. Wherein the thermoplastic binder fiber ends are disposed at the outer edge of the aggregate cluster, and wherein the interior of the aggregate cluster has little thermoplastic binder fiber ends. The absorbent structure of claim 1, wherein the macro absorbent structure further comprises staple fibers and superabsorbent particles intermixed with the staple fibers. The absorbent structure of claim 1, wherein the macro absorbent structure further comprises a thermoplastic binder long fiber, and wherein the aggregate cluster is constrained to the thermoplastic binder long fiber. The absorbent structure of claim 1, wherein the macro absorbent structure further comprises thermoplastic binder long fibers and superabsorbent particles bound to the thermoplastic binder long fibers. The absorbent structure of claim 1, wherein the macro absorbent structure further comprises thermoplastic binder long fibers and staple fibers constrained to the thermoplastic binder long fibers. The absorbent structure of claim 1, wherein the macro absorbent structure further comprises thermoplastic binder long fibers, superabsorbent particles constrained in the thermoplastic binder long fibers, and staple fibers constrained in the thermoplastic binder long fibers. The absorbent structure of claim 1, wherein the aggregate cluster further comprises superabsorbent particles bound to the thermoplastic binder fibers in the aggregate cluster. The absorbent structure of claim 1, wherein the aggregate cluster further comprises staple fibers constrained to thermoplastic binder fibers in the aggregate cluster. The method of claim 1 wherein the macro absorbent structure is a. 5-50% by weight meltblown elastomeric polyolefin binder fibers having an average fiber length of more than 1 cm; b. 1 to 50% by weight of cellulose fibers bound to the elastomeric polyolefin binder fibers; c. 30 to 90 weight percent of superabsorbent particles constrained or trapped in the polyolefin binder fiber; And d. An absorbent structure comprising from 1 to 50% by weight of aggregate clusters comprising meltblown polyolefin binder fibers, cellulose fibers bound to the polyolefin binder fibers in the aggregate cluster, and superabsorbent particles bound within the polyolefin binder fibers. a. Providing a first absorbent structure comprising a thermoplastic binder long fiber; b. Dividing the first absorbent structure to produce an aggregate cluster; c. Providing a stream of aggregate clusters; d. Providing a stream of extrusion melted polymer fibers; e. Integrating the aggregate cluster stream and the polymer fiber stream into a single product stream; And f. Collecting a single product stream on the forming surface to produce a second absorbent structure. The method of claim 10 further comprising incorporating a stream of superabsorbent particles in the aggregate cluster stream, polymer fiber stream, or single product stream. The method of claim 10 further comprising integrating the stream of wood pulp fibers in the aggregate cluster stream, polymer fiber stream, or single product stream. Disposable absorbent article produced by the method of claim 10.

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