Patent Application
20060149204
Disposable absorbent articles are common in today's society. For example, disposable diapers, disposable training pants, and disposable incontinence products are widespread in the marketplace.
However, currently known products suffer from a number of deficiencies. For example, many products include elastomeric components, such as waist elastics, leg elastics, tummy bands, and hip panels to improve the donning and fit attributes of the products. These products generally also include absorbent cores intended to absorb bodily fluids. It is desirable in most cases to construct such absorbent cores to have a relatively high absorbent capacity as well as to be relatively thin for discretion and comfort reasons. Often, these design considerations cause the absorbent cores to overlap or otherwise be in close proximity to the elastomeric components, hindering the ability of the elastomeric components to provide the intended benefits. For example, when absorbent cores are superposed over an elastomeric region of a product, the force required to elongate or retract that region of the product is generally increased. This can be particularly problematic in products constructed primarily of entirely of elastomeric materials intended to provide an “all-over” stretch.
Also, in certain applications, it is desirable to alert either the wearer or a caregiver that a garment has been wet. For example, it has been found beneficial to the toilet training process to alert children to the fact that they have had an accident. In other instances, it is desirable to notify a caregiver that wetting has occurred so that the wet garment can be removed, such as with a toilet-training child or with an incontinent person. Various mechanisms can be found in the prior art to provide the wearer and/or caregiver with such notification, but many are unsatisfactory. For example, audible wetness alarms are generally expensive and cumbersome. Water-soluble ink-printed graphics are often expensive, difficult to process, and prone to transfer to a wearer's skin, and generally must be placed in the crotch area of the diaper to ensure that they are wetted, making such graphics difficult to see by both the wearer and the caregiver.
Thus, there exists a variety of unmet needs in the disposable absorbent article art.
In response to the aforementioned unmet needs in the art, a new disposable absorbent article has been invented.
In one embodiment, the invention relates to a disposable absorbent article comprising a bodyside liner, an outer cover, and an absorbent core sandwiched between the liner and the outer cover, the absorbent core defining a longitudinal direction and a transverse direction, wherein the absorbent core exhibits planar growth of at least about 15% in at least one of the longitudinal and transverse directions at at least one measurement position when the absorbent core is tested in accordance with the Modified In-Product Planar Growth Test.
In another embodiment, the invention relates to a disposable absorbent comprising a chassis comprising a bodyside liner, an outer cover, and an absorbent core sandwiched between the liner and the outer cover, the absorbent core defining a longitudinal direction, a transverse direction, an absorbent core perimeter, and an absorbent core area. The absorbent core exhibits planar growth of at least 15% in at least one of the longitudinal and transverse directions at at least one measurement position when the absorbent core is tested in accordance with the Modified In-Product Planar Growth Test. The bodyside liner and the outer cover each extend beyond the absorbent core perimeter to define a chassis peripheral area. The bodyside liner and the outer cover are unconnected to each other within a portion of the chassis peripheral area to define an open area, and are connected to each other within at least a portion of the chassis peripheral area to define a sealed area. The open area is at least about 5% that of the absorbent core area.
In yet another embodiment, the invention relates to a disposable absorbent article comprising a chassis comprising a bodyside liner, an outer cover, and an absorbent core sandwiched between the liner and the outer cover, the absorbent core defining a longitudinal direction, a transverse direction, an absorbent core perimeter, and an absorbent core area. The absorbent core exhibits planar growth of at least 20% in at least one of the longitudinal and transverse directions at at least one measurement position when the absorbent core is tested in accordance with the Modified In-Product Planar Growth Test. The bodyside liner and the outer cover each extend beyond the absorbent core perimeter to define a chassis peripheral area. The bodyside liner and the outer cover are unconnected to each other within a portion of the chassis peripheral area to define an open area, and are connected to each other within at least a portion of the chassis peripheral area to define a sealed area. The open area is at most about 10% that of the absorbent core area.
Various aspects of the invention shall now be described in the context of a child's training pant, although it is understood that the principles of the invention have applicability to any variety of disposable absorbent articles, such as, for example, diapers, incontinence products, feminine hygiene products, disposable swimwear, and the like. As used herein, the phrase “absorbent article” refers to devices that absorb and contain body fluids, and more specifically, refers to devices that are placed against or near the skin to absorb and contain urine discharged from the body. The term “disposable” is used herein to describe absorbent articles that are not intended to be laundered or otherwise restored or reused as an absorbent article after being soiled.
Disposable absorbent articles according to various embodiments of the invention are representatively illustrated in
In particular embodiments, the liquid impermeable outer cover 24 can be both liquid and vapor impermeable, or can be liquid impermeable and vapor permeable. The liquid impermeable outer cover 24 is desirably manufactured at least in part from a thin plastic film, although other flexible liquid impermeable materials can also be used. The liquid impermeable outer cover prevents waste material from wetting articles, such as bedsheets and clothing, as well as the wearer and caregiver. The liquid impermeable outer cover 24 can include other materials, such as cloth-like nonwoven materials well known in the art.
The liner 22 is desirably compliant, soft feeling, and non-irritating to the child's, skin. Further, the liner 22 can be less hydrophilic than the absorbent core, to present a relatively dry surface to the wearer and permit liquid to readily penetrate through its thickness. Alternatively, the liner can be more hydrophilic or can have essentially the same affinity for moisture as the absorbent core to present a relatively Wet surface to the wearer to increase the sensation of being wet. This wet sensation can be useful as a training aid.
As discussed above, the absorbent core 26 may be located between the outer cover 24 and the liner 22. The absorbent core 26 can be any structure which is generally compressible, conformable, non-irritating to the child's skin, and capable of absorbing and retaining liquids and certain body wastes, and may be manufactured in a wide variety of sizes and shapes, such as, for example, hourglass shaped (
The absorbent article 20 can also incorporate other materials or components designed primarily to receive, temporarily store, and/or transport liquid to different regions of the absorbent core, thereby maximizing the absorbent capacity of the absorbent core. One suitable additional component is commonly referred to as a surge layer (not shown) and comprises a material having a basis weight of about 20 to about 200 grams per square meter, and in particular embodiments comprises a through-air-bonded-carded web of a homogenous blend of 60 percent 3 denier type T-256 bicomponent fiber comprising a polyester core/polyethylene sheath and 40 percent 6 denier type T-295 polyester fiber, both commercially available from Kosa Corporation of Salisbury, N.C., U.S.A.
Absorbent articles in accordance with the present invention can have front side panels 40 and back side panels 42 disposed on each side of the absorbent core 26. The side panels 40 and 42 can be permanently attached along seams to one or more components in the central section of the article, such as the liner and/or outer cover, using attachment means known to those skilled in the art such as adhesive, thermal or ultrasonic bonding. Alternatively, the side panels can be formed as an integral portion of one or more components of the article 20, such as a generally wider portion of the outer cover and/or liner, as is representatively illustrated in
In particular embodiments, such as a child's training pant, the front side panels 40 are attached to the back side panels 42 to define a three-dimensional pant-like configuration (not shown). In such embodiments, the front and back side panels can be permanently attached together using bonding means known in the art, or can be releasably connected with one another such as by a fastening system. A refastenable pant can comprise front fastening components 44 and mating fastening components 46. The side panels 40 and 42 suitably, although not necessarily, comprise an elastic material.
Any of the materials or components mentioned above can be non-stretchable, stretchable, or elastomeric. The absorbent articles of the present invention can also include waist elastics 48, leg elastics (not shown), and/or containment flaps (not shown), all of which are well known in the art.
Examples of the various materials and components that are referenced above and that are suitable for use in conjunction with the present invention are disclosed in U.S. Pat. No. 6,645,190 issued to C. P. Olson et al., U.S. Pat. No. 6,761,711 issued to Fletcher et al., U.S. patent application Ser. No. 10/729,485 in the name of Wyngaard, U.S. patent application Ser. No. 10/690,424 in the name of LeMinh et al., and U.S. patent application Ser. No. 10/835,638 in the name of Sperl, the entireties of which are hereby incorporated by reference to the extent consistent herewith.
Methods of absorbent article assembly per se are well known in the art, and a detailed recitation of the specific technical aspects of such methods is not necessary for an understanding of the present invention. Processes suitable for the assembly of disposable training pants are disclosed in U.S. Pat. Nos. 6,652,167 and 6,514,187 issued to Coenen et al., each of which is hereby incorporated by reference to the extent consistent herewith.
As used herein, “superabsorbent polymer,” “superabsorbent material,” “superabsorbent materials” and the like are intended to refer to a water-swellable, water-insoluble organic or inorganic material capable, under the most favorable conditions, of absorbing at least about 10 times its weight and, desirably, at least about 15 times its weight in an aqueous solution containing 0.9 weight percent of sodium chloride. Such materials include, but are not limited to, hydrogel-forming polymers that are alkali metal salts of: poly(acrylic acid); poly(methacrylic acid); copolymers of acrylic and methacrylic acid with acrylamide, vinyl alcohol, acrylic esters, vinyl pyrrolidone, vinyl sulfonic acids, vinyl acetate, vinyl morpholinone and vinyl ethers; hydrolyzed acrylonitrile grafted starch; acrylic acid grafted starch; maleic anhydride copolymers with ethylene, isobutylene, styrene, and vinyl ethers; polysaccharides such as carboxymethyl starch, carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose; poly(acrylamides); poly(vinyl pyrrolidone); poly(vinyl morpholinone); poly(vinyl pyridine); and copolymers and mixtures of any of the above and the like. The hydrogel-forming polymers are suitably lightly cross-linked to render them substantially water-insoluble. Cross-linking may be achieved by irradiation or by covalent, ionic, van der Waals, or hydrogen bonding interactions, for example. A suitable superabsorbent material is a lightly cross-linked hydrocolloid. Specifically, a more suitable superabsorbent material is a partially neutralized polyacrylate salt. Superabsorbent materials useful in the present invention are generally available from various commercial vendors, such as, for example, the Dow Chemical Company, Midland, Mich., U.S.A., Stockhausen Inc., Greensboro, N.C., or the BASF Corporation, Portsmouth, Va., U.S.A.
Suitably, the superabsorbent material is in the form of particles which, in the unswollen state, have maximum diameters ranging between about 50 and about 1,000 microns; suitably, between about 100 and about 800 microns; more suitably, between about 200 and about 650 microns; and most suitably, between about 300 and about 600 microns, as determined by sieve analysis according to American Society for Testing Materials Test Method D-1921. It is understood that the particles of superabsorbent material may include solid particles, porous particles, or may be agglomerated particles including many smaller particles agglomerated into particles falling within the described size ranges.
As representatively illustrated in
The absorbent core 26 of the present invention can exhibit planar growth when exposed to fluid. “Planar growth” as used herein refers to a lengthening,(in the longitudinal direction 50) or a widening (in the transverse direction 52) of the absorbent core 26 when wetted, or both, as opposed to a thickening. For example, as representatively illustrated in
In particular embodiments, the absorbent core 26 can expand at least about 5%, more particularly at least about 10%, more particularly at least about 15%, more particularly at least about 20%, more particularly at least about 25%, more particularly at least about 30%, more particularly at least about 35%, more particularly at least about 40%, more particularly at least about 45%, and still more particularly at least about 50% in the longitudinal direction 50. Furthermore, in particular embodiments, the absorbent core 26 can expand at least about 5%, more particularly at least about 10%, more particularly at least about 15%, more particularly at least about 20%, more particularly at least about 25%, more particularly at least about 30%, more particularly at least about 35%, more particularly at least about 40%, more particularly at least about 45%, and still more particularly at least about 50% in the transverse direction 52. For example, in the embodiment illustrated in
In particular embodiments, the bodyside liner 22 and the outer cover 24 are substantially unconnected to each other within a portion of the chassis peripheral area 29 to define an open area 31. The open area 31 can accommodate the planar growth of the absorbent core 26. Such a design can be desirable for a number of reasons. For example, to improve the fit and/or donning attributes of various absorbent articles, it can be desirable to design absorbent articles with stretchable or elastomeric components, such as the liner 22, outer cover 24, side panels 40/42, or to provide elasticity to the product via such means as waist elastics 48 or leg elastics (not shown). Placing an absorbent core near or over such stretchable or elastomeric components can hinder the ability of the elastomeric components to enhance product fit or donning as intended. In other words, the ability of the stretchable or elastomeric components to easily stretch can be stymied by the absorbent core, even if the absorbent core possesses some amount of extensibility. The present invention can in certain embodiments provide an absorbent article having an absorbent core that is relatively small in length and/or width in its initial dry state, and that will not assume an expanded length and/or width until it begins to soak up fluid. In this way, the fit and donning functions of the stretchable/elastomeric garment are maximized initially, and only impacted, if at all, near the end of the useful life of the product (i.e., after is has been partially or completely wet or soiled).
For example, in the embodiment of
The absorbent core 26 defines an absorbent core area 32, which is the area within the absorbent core perimeter 27 in its initial dry state. In particular embodiments, the absorbent article according to the present invention can include an open area 31 that is at least about 5%, more particularly at least about 10%, more particularly at least about 15%, more particularly at least about 20%, more particularly at least about 25%, more particularly at least about 30%, more particularly at least about 35%, more particularly at least about 40%, still more particularly at least about 50%, still more particularly at least about 60%, and still more particularly at least about 75% that of the absorbent core area 32. In particular embodiments, the more the absorbent core 26 is expected to expand upon wetting, the larger should be the open area relative to the size of the absorbent core area 26. “Area” as used herein when referring to a portion of a product refers to the particular area in question as measured when the product is in a laid-flat condition, uncontracted by any elastic components within the article.
Referring to
The graphic is desirably positioned such that when the absorbent core 26 experiences planar growth, at least a portion of the graphic 60 becomes concealed. For example, as representatively illustrated in
In a particular embodiment, the graphic can depict an absorption capacity “meter,” as representatively illustrated in
The graphic 60 can in particular embodiments be placed anywhere in the product as long as it becomes concealed following some amount of planar growth by the absorbent core 26. For example, as described above, the graphic 60 can be disposed on a layer of the outer cover 26 such that it will be concealed upon planar growth of the absorbent core 26 when viewed from the body-facing side of the garment 20. Alternatively, the graphic 60 can be disposed on the liner 22 such that it will be concealed upon planer growth of the absorbent core 26 when viewed from the garment-facing surface of the garment 20, such as when viewed through a transparent or translucent portion of the outer cover 24. In yet another alternative, representatively illustrated in
In other embodiments, it is desirable that the absorbent article 20 include little or no open area 31 within the chassis peripheral area 29. The dearth of open area 31 can restrict the planar growth of the absorbent core 26. Such a design can be desirable for a number of reasons. For example, if the chassis peripheral area 29 contains little or no room to accommodate the absorbent core's planar growth, the absorbent core can buckle, bunch up, bulge, or otherwise result in deformation of the absorbent article 20. In particular embodiments, such as in a child's training pant, such deformations can signal to the wearer that he or she has wet the garment due to the discomfort caused by the bulging pant. Furthermore, the deformation can result in a visible change to the appearance of the product, signaling to a caregiver that the garment has been wet and should be changed.
In particular embodiments, the deformation can provide a leakage-barrier function within the article. For example, as representatively illustrated in
Accordingly, in particular embodiments, the absorbent article according to the present invention can include an open area 31 that is at most about 50%, more particularly at most about 40%, more particularly at most about 30%, more particularly at most about 20%, more particularly at most about 15%, more particularly at most about 10%, more particularly at most about 5%, more particularly at most about 2%, and yet more particularly about 0% that of the absorbent core area 32. In particular embodiments, the more deformation and/or buckling that is desired in the product upon wetting, the smaller should be the open area relative to the amount of anticipated planar growth of the absorbent core 26.
Without wishing the following theory to limit the scope of the invention, it is believed that certain of the presently disclosed embodiments of disposable absorbent articles having absorbent cores according the present invention derive their planar growth characteristics from various unique combinations of superabsorbent material, elastomeric binder material, and other absorbent core materials. However, it is the inventors' intention that the claims set forth the scope of the invention, and that the presence or absence of particular absorbent core components are not intended to define the boundaries of the invention. Examples of constructions of absorbent cores that can provide the requisite planar growth characteristics include those disclosed in U.S. patent applications Ser. No. 10/699,193 in the name of Sawyer et al., Ser. No. 10/739,385 in the name of Zhang et al., Ser. No. 10/883,174 in the name of Zhang et al, and Ser. No. 10/955,430 in the name of Sperl et al., all assigned to Kimberly-Clark Worldwide, Inc., the contents of which are hereby incorporated by reference to the extent consistent herewith. A process suitable for constructing particular embodiments of such stretchable absorbent pads is described in U.S. Pat. No. 6,362,389 to McDowall et al. and assigned to Kimberly-Clark Worldwide, Inc., the content of which is hereby incorporated by reference to the extent consistent herewith. Moreover, it is believed that, with respect to one or more of the just-listed exemplary processes (such as the process disclosed in U.S. Pat. No. 6,362,389), the amount of longitudinal and/or transverse planar growth exhibited by absorbent cores can in particular embodiments be increased by the use of relatively high polymer melt temperatures, relatively low polymer throughput rates as compared to the speed of the absorbent core forming conveyor or drum, relatively high pressure of the air used to blow the binder polymer onto the forming surface, and the use of substantially integral, homogenous absorbent core structures (as opposed to absorbent cores comprised of multiple layers).
Particular embodiments according to the present invention shall be described by way of the Examples which follow below.
In-Product Planar Growth Test
The following In-Product Planar Growth Test can be used to examine the planar growth characteristics of an absorbent article.
The following Modified In-Product Planar Growth Test can likewise be used to examine the planar growth characteristics of an absorbent article. After performing the steps identified above for the In-Product Planar Growth Test, perform the following additional steps:
Prototype training pant chassis containing various components were assembled and tested to examine the impact of various absorbent core configurations on absorbent core planar growth. Each of the prototype chassis included an absorbent core sandwiched between a liquid-permeable liner material and a liquid-impermeable outer cover material. For each chassis, the liner was a 0.3 ounce per square yard (10 grams per square meter) polypropylene spunbond material, neck-stretched 35% to yield a resultant basis weight of 0.4 ounce per square yard, and treated with 0.35% by weight wetting agent; such a material is available from Kimberly-Clark Corporation, Dallas, Tex., U.S.A. For each chassis, the outer cover comprised a stretchable, elastomeric 32 grams per square meter liquid-impermeable film laminated to a 20 grams per square meter extensible polypropylene spunbond. The liner and the outer cover shared the same rectangular dimensions and had a length approximately 2.5 inches longer than the centerline length of the absorbent core 26, and a width approximately 2.5 inches wider that the width of the absorbent core 26 at its widest point.
The chassis of Examples 1-10 contained absorbent cores constituting a substantially homogeneous mixture of approximately 75% superabsorbent material, 10% cellulosic pulp, and 15% polymeric binder, where percentage amounts are by weight. The absorbent core of Example 11 constituted a substantially homogeneous mixture of approximately 63% superabsorbent material and 37% cellulosic pulp. With respect to the cellulosic pulp, codes 1-10 employed Rayonier Sulfatate HJ, available from Rayonier, Jesup, Ga., U.S.A, and code 11 employed NB 480, available from the Weyerhauser Co., Federal Way, Wash., U.S.A.
The Table below lists the superabsorbent polymers and polymeric binders that were used within each prototype. The superabsorbent polymer designated FAVOR SXM 9394 is available from Stockhausen, Inc., Greensboro, N.C., U.S.A. The superabsorbent polymer designated E1231-99 is available from the BASF Corporation, Portsmouth, Va., U.S.A. The polymeric binder designated Kraton G 2755 is available from Kraton Inc., Houston, Tex., U.S.A. The polymeric binders designated Vistamaxx® PLTD 1723 and Vistamaxx® 2210 are available from ExxonMobil Chemical Company, Houston, Tex., U.S.A. Each absorbent core had a thickness of approximately 1.5 millimeters (measured under a pressure of approximately 0.05 pounds per square inch), and defined a generally hourglass shape as representatively illustrated in
The absorbent core was attached to the center of the outer cover via one strip of 6 millimeter wide two-sided adhesive tape centered in the transverse direction 52 on the absorbent and extending the entire length of the chassis. The sealed area 30 of the chassis peripheral area was made by affixing the liner to the outer cover with 12 millimeter wide two-sided adhesive tape adjacent to the perimeters of the liner and outer cover materials. A strip of 6 millimeter wide two-sided adhesive tape was placed between the liner and outer cover, 35 millimeters transversely inward from each side edge of the chassis; these two strips of tape extended the entire length of the chassis and extended over and were affixed to regions of the hourglass-shaped absorbent core that extended within 35 millimeters of the side edges of the chassis.
The planar growth attributes of each code were measured using the Modified In-Product Planar Growth Test described below, with the exceptions that (1) the longitudinal growth of the core was measured only at the centerline position (as opposed to three transverse positions as specified in the Test), and (2) the transverse growth of the core was measured only at a single position 30 millimeters from the front end of the absorbent core (as opposed to three longitudinal positions as specified in the Test).
Having described particular embodiments of the invention in detail, it will be readily apparent that various changes and modifications can be made without departing from the spirit of the invention. All of such changes and modifications are contemplated as being within the scope of the invention as defined by the appended claims and any equivalents thereto.
