Hydrophobic components for disposable absorbent articles

Abstract

A disposable absorbent article, such as a diaper, having nonwoven hydrophobic leg cuffs, the disposable absorbent article having an inner layer comprising natural fibers derived from seasonally harvested flowers, fruits, seeds, or stems of plants, and a treatment applied to at least one surface of the inner layer to impart hydrophobic properties, the treatment comprising at least one compound selected from the group consisting of wax, urethane, silicone, fluorocarbon, and non-fluorochemical water repellent agents.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 374,576, filed September 5, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to hydrophobic topsheets / inner layers of liquid absorbent structures (absorbent articles) such as diapers, incontinence products, feminine hygiene products, and more particularly to disposable absorbent articles having hydrophobic topsheets / inner layers of liquid absorbent structures such as diapers, incontinence products, feminine hygiene products, and the like, which are promoted as more sustainable due to the use of natural fibers. [Background technology]

[0003] Articles used to absorb waste body fluids, such as urine, blood, and menstrual flow, are in widespread use throughout the world. These articles are commonly referred to as "absorbent articles." Typically, these articles come in the form of diapers and other similar products, such as feminine hygiene and incontinence products, and have become increasingly prevalent modern utilities and necessities.

[0004] Absorbent articles in the form of diapers generally come in two varieties: reusable cloth diapers and disposable diapers. Modern cloth diapers include liners, such as flushable liners, that retain waste material for disposal in a toilet or other similar device. Disposable diapers grew significantly in popularity in the mid-1980s with the introduction of superabsorbent polymers (SAPs), such as, but not limited to, TRO C, sodium polyacrylate, and polyacrylamide copolymers, into diapers, and an estimated 90% of parents in the United States now use disposable diapers.

[0005] A basic disposable diaper has the following components: (a) an inner layer or topsheet that serves as the first layer adjacent to the baby's skin and thus comes into contact with liquid and / or solid waste. This inner layer or topsheet is most often made from some type of petroleum-based plastic or plastic-treated material, although some environmentally conscious diaper companies use plant-based plastics (also known as bioplastics) or hydrophilic cotton blends to provide this layer; (b) an absorbent core that absorbs and retains liquids. Most absorbent cores are made from "fluff," which can be made from wood pulp fibers or corn- or wheat-based materials and can contain crystals and / or regular superabsorbent materials (SAPs) dispersed throughout the fluff, so that the fluff acts to distribute the liquid while the SAP absorbs and "traps" fluids within the core and away from the baby; and (c) a waterproof outer layer, or sometimes a semi-outer layer (e.g., film), that provides a waterproof coating / layer. This coating or layer is often made from some type of petroleum-based plastic or plastic-treated material, although some environmentally conscious diaper companies use plant-based plastics (also known as bioplastics) to provide this layer. (d) A film covering layer (backsheet) that provides a different feel than the waterproof coating / layer. Such film covering layers are often made from some type of petroleum-based plastic or plastic-treated material, like the film layer, although some environmentally conscious diaper companies use plant-based plastics (also known as bioplastics) and / or cellulosic nonwovens to provide this layer. This backsheet layer is typically used solely to provide a softer feel to the outer surface of the absorbent article than would be achieved with just the film layer, which is exposed as the outermost layer.

[0006] Topsheets are most commonly made from polyethylene or polypropylene woven, nonwoven, or porous formed film materials and are highly hydrophilic. Therefore, liquids are rapidly absorbed through the topsheet into the core and trapped within the fluff (SAP). These common plastics are synthetic and not susceptible to moisture recovery, eliminating the rewet issue. Backsheet materials typically include a flexible polyethylene sheet with a film barrier. The backsheet can be made of the same material as the topsheet, but in some cases, the inner surface of the backsheet also includes a film barrier (which functions as a liquid barrier to prevent leakage through the diaper), either as a separate component or with the film bonded to the inner layer of the backsheet. The outer surface of the backsheet is constructed of a soft-touch backsheet material (e.g., nonwoven polyethylene), thus concealing the film barrier within a conventional diaper construction.

[0007] The widespread use of disposable diapers has led to a large volume of use each year, resulting in massive waste disposal and a growing environmental problem. The majority of commercially available disposable diapers are primarily composed of unsustainably sourced polypropylene- and polyethylene-based plastics. Manufacturers of such products generally give little or no consideration to the environmental impact of their production on the planet. On a more positive note, some environmentally conscious plastic manufacturers have begun to incorporate recycling and / or biopolymers with additional processing, such as enzymes embedded in plastics to help bacteria begin to degrade the polymer matrix after disposal. Regardless of whether recycling or enzyme-containing biopolymers are used, these environmentally conscious processes still have negative or harmful effects on the environment due to pollutants released during the extrusion and / or manufacturing processes.

[0008] In fact, synthetic polymers are a major problem because they are often disposed of in landfills, where they will continue to slowly leach toxins into the soil over time for centuries to come. Most notably, the average disposable diaper can take 500 years to decompose and contains petroleum, plastic, fragrances, wood pulp, and dioxins.

[0009] In particular, the liquid-permeable facing and leak-proof backing materials in many, if not most, disposable diapers are not sustainable (i.e., meet the needs of the current generation without compromising the needs of future generations, ensuring a balance between economic growth, environmental protection, and social welfare). That said, we are seeing liquid absorbents made from fluff pulp being sourced more sustainably through more sustainable forest management practices. However, these new sustainability efforts, while a step in the right direction, take time. For example, it still takes an average of 5 to 20 years to grow harvestable Nordic spruce and pine trees for the pulpwood market.

[0010] Therefore, what is desired is a sustainable absorbent structure composed of natural materials derived from plant flowers, fruits, seeds, and stems, rather than pulp from fully mature trees or known SAPs. Such flower / fruit / seed / stem sustainable absorbent structures would have a soft and supple feel in both the innermost and outermost layers, as well as excellent absorbency and rewetting performance and excellent leak prevention. Furthermore, these flower / fruit / seed / stem structures would only require one growing season to harvest, rather than 15-20 years, and would perform similarly to standard plastic absorbent articles, regardless of biodegradation testing status.

[0011] Many absorbent articles are beginning to incorporate more natural fibers, such as cotton and bamboo, primarily in various blends. While such natural fibers are known for use in various layers, they are typically used in topsheets. These natural fibers are primarily cellulosic in nature and tend to absorb and retain liquid rather than rapidly transporting it to the core and trapping it away from the skin. Therefore, wearers of these natural fiber-based absorbent articles tend to remain wet, and rewet data indicates a much higher likelihood of rewet than those wearing absorbent articles containing standard synthetic fibers. Such topsheets need to be improved to perform more like plastics, both in terms of rewet and moisture transport to the core (also known as "strike through"). The goal is to achieve a top layer with rapid liquid penetration or a high liquid penetration rate and low rewet values.

[0012] Other absorbent articles, such as feminine hygiene and incontinence products, have a similar structure to the disposable diapers described above, for example, with a topsheet and core to contain moisture once it reaches them. There are currently no products on the market that meet the market need with an advanced topsheet containing natural fibers that does not retain liquid and leave the skin overly wet.

[0013] U.S. Patent 11,382,801 B2 ("the '801 patent") discloses a topsheet material having apertures defined within a specific angular range. However, absorbent articles formed with the apertured sheet material disclosed in the '801 patent, whose apertures have specific angles that form a conical shape, extrude moisture from the topsheet through pores (e.g., using cotton fibers) to the core, but do not overcome the drawback of using cotton, which expands and closes the pores in the fabric as it absorbs and retains liquid. The absorbent article of the '801 patent may be prevented from properly transporting liquid to the core, resulting in poor performance as an absorbent article and causing leakage and wetness at the apertures facing the wearer. Furthermore, such absorbent articles and topsheet materials (see, e.g., column 8, lines 39-63) are not formed using sustainable materials that exhibit rapid or fast liquid permeability and low rewet values.

[0014] WO 2017 / 015477 A1 discloses a bio-based and / or biodegradable disposable diaper. The diaper is composed of an inner layer of nonwoven fabric containing natural fibers, an outer layer of nonwoven fabric containing natural fibers and a hydrophobic treatment, and a core containing natural fibers or fibrous materials disposed between the inner and outer layers. However, the inner layer of nonwoven fabric, although made of 100% cellulose fibers, exhibits poor performance because it absorbs and retains up to 150 times its weight in liquid before transferring excess liquid to the core. This leaves the wearer's skin excessively wet, rather than transferring and trapping the majority of the liquid in the core. Furthermore, disposable biodegradable diapers perform poorly with respect to rewet when moisture migrates through the inner layer to the core and the wearer places even a small amount of weight on the structure. For example, when a baby sits down, liquid migrates back to the inner layer, which is held adjacent to the skin, resulting in poor performance and leakage.

[0015] Because performance-enhancing technologies can potentially result in poor tactile sensation, no systems and / or technologies have been introduced to address performance issues. In its teachings, tactile sensation concerns are not addressed to the wearer, but rather to the outermost layer of the garment. Furthermore, the disposable biodegradable diaper disclosed in WO 2017 / 015477 A1 contains loose fluff and a core of SAP, which causes loose fluff with too short a pile to become lint. This lint not only migrates through the diaper's topsheet and adheres to the baby's skin, but also is released into the air, where it can be inhaled and potentially cause lung damage. Furthermore, the presence of such loose fluff and SAP alone causes the SAP to settle at the lowest point of the diaper, resulting in large agglomerates of SAP particles in the center of the diaper. This results in a reduced level of maximum absorbency and discomfort for the baby, who experiences a diaper with a large drooping center.

[0016] WO2016 / 023016A1 discloses a bio-based and / or biodegradable disposable diaper. The diaper includes a bio-based and / or biodegradable outer sheet that is impermeable to aqueous media, a bio-based and / or biodegradable inner sheet that is permeable to aqueous media, an absorbent pad made of natural fibers and a bio-based superabsorbent, bio-based and / or biodegradable side sheets, fastening tabs, and an elastic waist strip. In particular, the outer sheet, inner sheet, side sheet, fastening tabs, and fastening mat are said to be made from a thermoplastic polymer selected from the group consisting of aliphatic polyesters, aromatic polyesters, cellulose fibers, nonwoven materials, and combinations thereof.

[0017] Another problem with certain thermoplastic polyesters and cellulosic fibers such as those disclosed in WO2016 / 023016A1 is that most, if not all, thermoplastics are not sustainable. Biodegradable treatments for natural fibers are not sustainable, even if they are biodegradable and configured to pass ASTM Test Method D5511-12, ASTM Test Method 5338.92, or ISO CD Test Method 14855, as the references teach. Furthermore, WO2016 / 023016A1 does not address the issues of natural fibers and their poor rewet performance, nor does it offer solutions to the high tendency of cellulosic materials to absorb and not efficiently transfer liquid to the core.

[0018] WO2018020061A1 discloses a personal hygiene product using a cotton core with a plurality of microcapsules containing an active ingredient to be released onto the skin. However, it is undesirable to deposit the SAP or ingredients contained therein out of the core and onto the user's skin. Rather, it is desirable to keep the SAP in place within the core, keeping moisture away from the skin surface.

[0019] Furthermore, the inventors are not aware of any diaper product that actually comprises a sustainable nonwoven hydrophobic inner layer, including natural materials derived from plant flowers / fruits / seeds / stems, which are of course sustainable and also comprise multiple pores, and which inner layer exhibits low internal water absorbency and good rewet performance. Summary of the Invention

[0020] Thus, the present invention provides a sustainable absorbent structure made from natural materials derived from the flowers / fruits / seeds / stem of plants, overcoming the drawbacks of the prior art.

[0021] In one aspect, these sustainable absorbent structures of the present invention have a hydrophobic topsheet that provides superior absorbency by forcing liquid into the core rather than trapping it on the surface as with conventional cellulosic topsheet structures. The hydrophobic topsheets of the present invention also exhibit good, low rewet and excellent leak-proofing performance in addition to a soft and supple feel.

[0022] Additionally, using flower / fruit / seed / stem materials rather than tree-based fibers eliminates the need for materials that, while sustainable, can take 15-20 years to harvest. Meanwhile, flower / fruit / seed / stem materials can be achieved in a single growing season and, regardless of biodegradation testing status, have been shown to approach or surpass the performance of standard plastic absorbent articles while remaining sustainable.

[0023] The topsheet of the present invention, which comprises natural materials derived from plant flowers / fruits / seeds / stems, has a plurality of pores and hydrophobic properties that enhance its rewet performance without compromising the sustainability of the topsheet itself, thereby providing comfort to the wearer while exceeding the properties of standard, non-sustainable plastic topsheets.

[0024] In a preferred embodiment, the topsheet, in the form of a diaper, is composed entirely or substantially of a sustainable material that has a rewet of less than 40 grams and a breathability of faster than 8 seconds using standardized INDA test methods for single pass, rewet, and multiple pass. Such absorbent articles, including diapers, also have a soft feel on their inward-facing surface.

[0025] The topsheet of the present invention for use in disposable absorbent articles preferably comprises a substantially all-natural material derived from the flowers / fruits / seeds / stems of plants, is preferably hydrophobic, and preferably comprises a plurality of pores.

[0026] In a further preferred embodiment, the topsheet of the present invention for use in a disposable absorbent article comprises an inner layer of a nonwoven fabric comprising natural materials derived from the flowers / fruits / seeds / stems of plants, the inner layer of the nonwoven fabric being unbleached to maintain the hydrophobicity provided by the original lignin and / or treated with at least one compound selected from the group consisting of waxes, urethanes, silicones, fluorocarbons, and non-fluorochemical water repellents applied to at least one surface thereof.

[0027] In some cases, the treatment is applied to the inner layer at a solids loading of 0.0015% to 2.5% by weight. In particularly useful embodiments, the treatment is applied at a loading of about 1.55% by weight. In some embodiments, the hydrophobic treatment is applied only to the top surface of the inner layer. In another particular embodiment, the treatment is applied to the bottom and top surfaces of the inner layer.

[0028] In certain embodiments, no treatment is applied to the inner layer, which is composed of unbleached cellulose fibers mixed with synthetic fibers such as polyethylene, polypropylene, polyester, or other thermoplastic polymer matrix materials. In certain embodiments, the cellulose content is 10% or greater.

[0029] In certain preferred embodiments, the inner layer of the absorbent article is treated with a dendrimer wax. In some of these embodiments, the treatment is applied to the top surface of the inner layer. In some embodiments, the treatment is applied to the top and bottom surfaces of the inner layer.

[0030] In certain preferred embodiments of the absorbent article, the inner layer comprises a plurality of pores.

[0031] The absorbent article so constructed may be a diaper, nappy, absorbent underpants, training pants, adult incontinence product, pet incontinence product, feminine hygiene product, wound dressing, or breast pad.

[0032] The present invention also includes a sustainable diaper formed of an inner layer of nonwoven fabric comprising cotton treated with a hydrophobic agent selected from the group consisting of wax, urethane, silicone, fluorocarbon, and non-fluorochemical water repellent agents, and combinations thereof, an outer layer comprising cotton, and an absorbent core comprising cotton and polyacrylate high-absorbency particles disposed between the inner and outer layers.

[0033] In some cases, the diaper has a treatment consisting of dendrimer wax applied to the inner layer. In some such cases, the treatment is applied to the inner layer at a solids loading of 0.0015% to 2.5% by weight. In particularly useful embodiments, the dendrimer wax is applied at a loading of about 1.55% by weight. In some embodiments, the hydrophobic treatment is applied only to the top surface of the inner layer.

[0034] In some cases, the diaper has a treatment consisting of paraffin wax applied to the inner layer. In some such cases, the treatment is applied to the inner layer at a solids loading of 0.5% to 1.2% by weight. In particularly useful embodiments, the paraffin wax is applied at a loading of about 0.75% by weight. In some embodiments, the hydrophobic treatment is applied only to the top surface of the inner layer.

[0035] In certain embodiments, the diaper has a rewet of less than 40 grams and a breathability of faster than 8 seconds using INDA's standardized test methods for single pass, rewet, and multiple pass. Generally, breathability and rewet performance have an inverse relationship: when breathability is fast, rewet is high, and vice versa.

[0036] Table 1 below shows multiple pass data generated using INDA's standardized test method, comparing dendrimer-treated topsheets in diapers with commercially available plastic diapers. Performance is considered acceptable if multiple passes are less than 6 seconds. [Table 1]

[0037] Table 2 below shows single-pass data generated using INDA's standardized test method, comparing dendrimer-treated topsheets in diapers with commercially available plastic diapers. A single-pass time of less than 6 seconds is considered acceptable performance. [Table 2]

[0038] Table 3 below shows rewet data generated using INDA's standardized test method, comparing dendrimer-treated topsheets in diapers with commercially available plastic diapers. Performance is considered acceptable if rewet is less than 0.25 grams. [Table 3]

[0039] Table 4 below shows multiple fluid pass data generated using INDA's standardized test method, comparing the dendrimer-treated topsheet fabric alone to an untreated 100% cotton fabric. [Table 4]

[0040] Table 5 below shows single fluid pass data generated using INDA's standardized test method, comparing the dendrimer-treated topsheet fabric alone to untreated 100% cotton. [Table 5] Table 6 below shows rewet data generated using INDA's standardized test method, comparing the dendrimer-treated topsheet fabric alone with an untreated 100% cotton fabric. [Table 6]

[0041] These and other objects of the present invention, as well as the specific features and advantages of the present invention, will become more apparent upon consideration of the following drawings and the accompanying detailed description. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1 is a perspective view of a preferred absorbent article in the form of a diaper made in accordance with the present invention.

[0043] [Figure 2] FIG. 2 is a cross-sectional view of the diaper according to the first embodiment.

[0044] [Figure 3] FIG. 3 is a cross-sectional view of a diaper according to a second embodiment.

[0045] [Figure 4] FIG. 4 is a cross-sectional view of a diaper according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0046] The following definitions and methods are provided to better define the present invention and to guide those of ordinary skill in the art in the practice of the present invention. Unless otherwise specified, terms are to be understood according to conventional usage by those of ordinary skill in the relevant art.

[0047] As used herein, the terms "top," "bottom," "above," "below," "over," "under," "above," "beneath," "on top," "underneath," "up," "down," "upper," "lower," "front," "rear," "back," "forward," and "backward" refer to the objects referred to when in the orientation shown in the drawings, although this orientation is not required for the purposes of the invention.

[0048] Growing season means a period of 12 months or less.

[0049] Seasonal harvesting means that the flowers, fruits, seeds, stems and trunks are removed from the plant or soil within 12 months of emergence.

[0050] As used herein, the term "nonwoven" fabric or web means a web having an intertwined configuration of individual fibers or yarns, but not in a manner identifiable as a knitted or woven fabric. Nonwoven fabrics or webs can be formed by a variety of processes, including, but not limited to, meltblowing, spunbonding, spunlacing, and bonded carded web processes.

[0051] As used herein, the term "spunbond fibers" refers to small-diameter fibers of polymeric material that have been mechanically and / or inductively stretched. Spunbond fibers are typically formed by extruding molten thermoplastic material as filaments through multiple fine capillaries in a spinneret, where the diameter of the extruded filaments rapidly decreases. Examples of spunbond fibers and methods for their production are described, by way of example only, in U.S. Pat. No. 4,340,563 to Appel et al., U.S. Pat. No. 5,382,400 to Pike et al., and U.S. Pat. No. 5,795,926 to Pike et al., the entire contents of which are incorporated herein by reference. Spunbond fibers are typically non-tacky and continuous when deposited on a collecting surface.

[0052] As used herein, "spunlaced fibers" refers to fibers produced by a process involving the cohesion and entanglement of basic fibers with one another, typically by intermixing the fibers using multiple jets of pressurized water passed through a moving fleece or fabric. By way of example, methods for producing spunlaced nonwoven fabrics are described in U.S. Patent Nos. 3,214,819, 3,485,706, and 3,508,308, the entire contents of which are incorporated herein by reference.

[0053] As used herein, the term "meltblown fiber" generally refers to fibers of polymeric material formed by extruding molten thermoplastic material as molten threads or filaments through multiple die capillaries into converging, high-velocity air streams, which attenuate the molten thermoplastic filaments. The meltblown fibers can then be carried by the high-velocity gas streams and deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Meltblowing processes are disclosed, by way of example only, in U.S. Patent No. 5,271,883 to Timmons et al., U.S. Patent No. 5,160,746 to Dodge et al., U.S. Patent No. 4,526,733 to Lau, U.S. Patent No. 5,652,048 to Haynes et al., and U.S. Patent No. 5,366,793 to Fitts et al., the entire contents of which are incorporated herein by reference. Meltblown fibers generally have an average diameter of less than about 10 micrometers and, unlike spunbond fibers, are typically tacky when deposited onto a collecting surface, resulting in them bonding to each other during the deposition process.

[0054] The term "disposable" is used herein to describe absorbent articles that are not intended to be laundered or restored or reused as absorbent articles. These articles are intended to be discarded after a single use, preferably in an environmentally friendly manner.

[0055] The terms "personal product," "absorbent product," and "absorbent article" are used interchangeably herein and are intended to include products or articles used to absorb excreted body fluids or other bodily wastes, including diapers, nappies, absorbent underpants, training pants, adult incontinence products, pet incontinence products, feminine hygiene products, wound dressings, and breast pads. It should be understood that this list is not exhaustive and that the teachings of the present invention may be implemented with other types of products intended to absorb liquids.

[0056] The phrase "foam structure" is intended to include products or articles made by a process in which oily chemicals are mixed and reacted to change from a liquid to a solid state. "Foam" can be injected into a mold or formed into large block structures. Foam is a flexible and porous substance made from natural or synthetic compounds containing a variety of ingredients, which, after forming, results in a product that is 80-85% air and 15% solids.

[0057] 1 and 2 illustrate an absorbent article (personal product) 100 according to one exemplary embodiment, specifically, the absorbent article 100 in the form of a disposable diaper for infants (babies). The illustrated diaper 100 is merely an exemplary embodiment, and it should be understood that the teachings of the present invention may be practiced with infant training pants / diapers and other similar absorbent products, as well as other absorbent products whether or not mentioned herein. FIGS. 1 and 5 are perspective views of different embodiments of the diaper 100, and FIG. 2 is a cross-sectional view of the diaper 100.

[0058] The diaper 100 is generally formed of an inner layer (topsheet) 200, an inner acquisition / distribution layer and / or absorbent core 300, a film layer 407, and an outer shell or cover (backsheet) 400 as shown.

[0059] In some examples, side panels, also known as leg cuffs 500 (see FIG. 1 ), are also provided, which are configured to effectively prevent leakage at the sides of the diaper 100, thereby keeping the skin dry and protected. In some embodiments, the leg cuffs 500 can be configured as a pair with not only (outer) leg cuffs 500 but also inner standing cuffs or gathers 501. As shown in FIG. 1 , the leg cuffs 500 or gathers 501 (not shown) are typically formed in the center of the diaper 100.

[0060] In one exemplary embodiment, each leg cuff 500 is formed from a nonwoven material containing fibers derived from the flowers, fruits, seeds, or stems of plants. In the diaper of FIG. 1, each leg cuff 500 is preferably formed from a hydrophobically treated nonwoven cotton structure with a spandex inlay to provide the desired elasticity. If the diaper 100 includes a defined elastic waistband, this too can be formed from a nonwoven material containing fibers derived from the flowers, fruits, seeds, or stems of plants, such as a cotton structure with a spandex inlay to provide elasticity.

[0061] It should be understood that the elastic structures can be formed from other materials, such as spandex or other synthetics. As described herein, elastic structures are used in the leg cuffs and can also be used in the side panels and tape structures. Moreover, many gasket cuffs use spandex to provide a seal against the infant's legs.

[0062] In a preferred embodiment, the leg cuffs 500 are constructed from hydrophobically treated cotton and spandex. Flaps 504 having fasteners 506 are provided to hold the diaper 100 in a substantially sealed relationship to the wearer's body. Fasteners include biocompatible adhesive coatings, such as pressure-sensitive adhesives, and dissolvable adhesive films, such as those derived from acrylates, silicones, polyurethanes, natural rubbers, hydrocolloids, and hydrogels. Rubber-based adhesives are tough, moisture-resistant, and weather-resistant. inner layer

[0063] As previously mentioned, the inner layer 200 plays a critical role in the construction of the diaper because it is the layer adjacent to the most sensitive areas of the baby's body, sometimes for hours at a time, and the quality and construction of the inner layer 200 layer also determines the level of absorbency, rewet, breathability, and comfort (softness) for the baby.

[0064] According to the present invention, the inner layer 200 is formed from natural materials (e.g., 100% organic cotton or coconut) derived from the flowers, fruits, seeds, or stems of plants. More specifically, the inner layer 200 comprises a nonwoven fabric (material) formed from natural fibers derived from the flowers, fruits, seeds, or stems of plants.

[0065] Any number of different natural fibers derived from the flowers / fruits / seeds / stem of plants can be used to form the nonwoven inner layer 200, provided they are suitable for the intended use described herein. Exemplary natural fibers derived from flowers / fruits / seeds / stem include, but are not limited to, cotton, linen, coconut, flax, bamboo, and the like.

[0066] Cotton is the most widely used natural fiber, highly absorbent, easy to care for, and comfortable for babies. Cotton is almost pure cellulose, soft to the touch, and has excellent breathability. Like many materials, cotton is available commercially in organic form, which is generally understood to mean that the cotton is grown without the use of fertilizers or synthetic pesticides such as insecticides.

[0067] Bamboo is a sustainable crop that provides a readily available source of natural fiber. Bamboo has a fast growth cycle, so when it is harvested it can be quickly replaced with a new crop. Bamboo does not typically require fertilizer or pesticides to grow. Bamboo is suitable for diapers because it is soft and becomes highly absorbent when processed.

[0068] Linen is a sustainable crop. Like bamboo, linen's rapid growth cycle allows it to be quickly replaced by a new crop at harvest. In terms of moisture absorption, linen can hold 20% of its weight in water before feeling wet, and requires about one-fifth the pesticides and fertilizers required to grow cotton. Linen produces long fibers that produce little to no lint, are static-free, repel insects, are non-allergenic, and are fairly stain-resistant. Linen fibers also have antibacterial properties.

[0069] It should also be understood that the inner layer 200 may be formed as a mixture of two or more of the natural materials mentioned above.

[0070] It should also be understood that the inner layer 200 may be formed as a blend of any of the natural materials mentioned above with a thermoplastic polymer such as polyethylene, polypropylene, polyester, or the like.

[0071] Most cotton-based personal / absorbent products are preferably constructed with layers formed using spunbond or spunlace fibers.

[0072] The inner layer 200 can be either hydrophobically treated on one side and hydrophilically treated on the other side, or hydrophobically treated on only one side or both sides. More specifically, the nonwoven material forming the inner layer 200 can be surface treated using a treatment composition that imparts either hydrophilic or hydrophobic properties. Any number of different surface treatments can be used to increase the hydrophilicity imparted to the nonwoven. For example, chemicals such as surfactants, wetting agents, and rewetting agents can increase the hydrophilicity of a material, turning an otherwise hydrophobic fabric into a hydrophilic fabric. With respect to fibers, natural fibers tend to be hydrophilic, especially if natural oils have been removed from them. The surface treatment can be carried out using any number of suitable techniques; more specifically, common treatments include immersing the nonwoven in a treatment bath, coating or spraying the nonwoven with a treatment composition, and printing the nonwoven with a treatment composition.

[0073] When a nonwoven web is formed from a hydrophobic material or exhibits hydrophobic properties, it is often desirable to modify the surface of the nonwoven web using a hydrophilic surfactant to enhance the web's wettability. To achieve this goal, an external hydrophilic surfactant is typically applied to the surface of the nonwoven web. An internal hydrophilic surfactant is typically mixed with the material (e.g., cellulose fibers) used to form the nonwoven web and then transferred to the surface after the nonwoven web is formed. External and internal hydrophilic surfactants can be characterized by their durability and wettability.

[0074] The durability of a surfactant generally refers to its ability to withstand stresses, such as repeated washing cycles of a nonwoven fabric, without being removed from the fabric or losing effectiveness. The wetting ability of a surfactant generally refers to its ability to transform a hydrophobic nonwoven web into a fabric that readily absorbs and distributes aqueous fluids. Surfactants that cause an originally hydrophobic nonwoven web to absorb fluids relatively quickly and with high fluid uptake are referred to as high wetting surfactants. Surfactants that cause a nonwoven web to absorb aqueous fluids relatively slowly and with low fluid uptake are referred to as low wetting surfactants.

[0075] The surface treatment of the topsheet layer is configured to increase the hydrophobicity of the nonwoven by increasing the surface tension of the nonwoven, increasing the contact angle with liquids, and making the topsheet completely fluid-repellent when liquids are introduced to the topsheet independently of the overall structure of the diaper.

[0076] 1, which is also applicable to other embodiments, the inner layer 200 includes a plurality of openings or pores 202, such as those found in a gauze-like material. These openings (pores 202) readily allow fluid to pass through to the inner acquisition / distribution layer and / or absorbent core 300 (FIG. 2), preventing liquid from being retained on the surface of the nonwoven inner layer 200 that contacts the skin.

[0077] The nonwoven inner layer 200 can be formed by any number of suitable processes, including, but not limited to, hydroentanglement, carding, air-laying, heat treatment, or other suitable processes. Holes, dot matrices, or perforations can be formed during the nonwoven formation process or can be applied to the nonwoven after formation. Any number of means can be used to create these openings (e.g., pores 200) in a preformed nonwoven, including, but not limited to, air jet formation during extrusion or molding, laser formation, or passing the sheet through a roller mill with microspikes suitable for forming holes in the sheet. Additionally, porous sheets can be formed by incorporating microparticles of a water-soluble material into the sheet and then passing the sheet through a water bath after formation. The water dissolves the microparticles, creating the pores. In a particularly preferred embodiment, the pores are structurally constructed during the formation of the cotton sheet.

[0078] The openings or pores 220 in the inner nonwoven layer 200 can be any shape that allows the passage of liquid, and are preferably oval or circular. The openings typically have a diameter of about 0.07 cm to about 0.40 cm. The pores 202 in the inner nonwoven layer 200 preferably have a diameter of 0.18 cm to 0.23 cm.

[0079] Furthermore, the plurality of pores 202 and the hydrophobic nonwoven topsheet 200 together create a system that improves rewet performance, keeping liquids near the diaper core 300 and preventing wetness from passing through the diaper back to the skin. Thus, the surface treatment of the topsheet 200 is configured to enhance the hydrophobicity of the nonwoven by increasing its surface tension, increasing its contact angle with liquids, and making it more fluid-repellent. This tension is at a level where the plurality of pores alone will retain water droplets and not allow water to pass through the pores due to the high surface tension and contact angle without superior high-wetting surfactants located on the interior surface of the topsheet itself or underneath the topsheet structure, either in the ADL layer, core wrap, or core itself.

[0080] Figure 2 shows a surface treatment 205 applied to the top, i.e., skin-contacting, surface of the nonwoven inner layer 200. Figures 3 and 4 both present another embodiment showing a surface treatment 206 applied to the bottom, i.e., the surface closer to the respective core 300, of the nonwoven inner layer 200. In the embodiment of Figure 4, surface treatments 205, 206 are applied to both the top and bottom surfaces of the inner layer 200.

[0081] It should also be understood that the surface treatment applied to the inner layer 200 can be configured as a finish that renders one side hydrophobic and the other side pristine, a finish that renders one side hydrophobic and the other hydrophilic, or a finish that renders both sides of the inner layer hydrophobic.

[0082] In some embodiments, the treatment may include Finish RPW dendrimer wax dispersion, ethoxylated alcohol-containing Nylwick (or Nylwck) modified water-dispersible polyester, Aquatek Uno sulfonated nylon, Block S sulfonated nylon, WSR XF non-fluorinated water repellent, NF-21 fluorinated (C6) surfactant, HCO16, and / or Ethox 2191. A particularly preferred form is provided as Finish Nylwck by Phoenix Chemical Company. In certain preferred embodiments, the treatment may include Permaseal WSR-XF C6 fluorocarbon and / or Flexiwet NF non-fluorocarbon silicone water repellent.

[0083] In certain embodiments, the hydrophobic treatment includes a dendrimer wax. In some of these embodiments, the treatment includes a RPW. Dendrimer waxes that can be used in the present invention are available in liquid form and can be applied to nonwoven materials by many techniques known to those skilled in the art. An advantage of wax-based treatments is that, as opposed to fluorocarbons, waxes have a reduced environmental impact.

[0084] In one embodiment, the treatment is applied to natural fibers at 0.0015% to 2.5% solids. In some embodiments, the treatment is applied at 0.005% to 0.75% solids. In some of these embodiments, the treatment is applied at about 0.25% by weight. In particularly preferred embodiments, the treatment is applied to the fabric at 0.005% to 0.35% by weight. It is important to apply at least 0.0015% by weight of the hydrophobic treatment to the outer layer. It is believed that the use of low levels of such ingredients in the described ranges allows the treated fabric to retain hydrophilic properties, as opposed to the water resistance and repellency imparted to fabrics by higher concentrations of such chemicals.

[0085] In some particularly preferred embodiments, the present invention involves applying about 1.55% by weight of a finished RPW dendrimer wax to a nonwoven cotton or cotton-elastomer blend. It is particularly effective to apply a treatment containing dendrimer wax or dendrimer wax emulsion to the inner (top) surface of the outer sheet.

[0086] As used herein, the terms "percent," "%," "percent solids," and "wt. %" all refer to the weight percent of the indicated ingredient or content in the product or composition in which it is present, after drying and without dilution, unless otherwise dictated by the context in which the term is used. When the treatment is applied to fabric, percent, "%," "percent solids," and "wt. %" refer to the amount applied to the fabric when dry, unless otherwise specified.

[0087] Processing solutions and suspensions comprise various weight percentages of processing compositions in water unless another solvent / diluent is indicated.

[0088] An external hydrophobic agent is applied to the surface of the nonwoven web. An internal hydrophobic agent is mixed with the materials used to form the nonwoven web and then migrates to the surface after the nonwoven web is formed. External and internal hydrophobic agents can be characterized in the same manner as the hydrophilic agents described above with respect to their durability and wettability.

[0089] Also shown in Figure 2 is a surface treatment 205 applied to the upper, i.e., skin-adjacent, surface of the nonwoven topsheet 200. In the embodiment of Figure 3, a surface treatment 206 applied to the lower, i.e., the surface closer to the core 300, surface of the topsheet 200 is shown as a key feature, and in the embodiment of Figure 4, surface treatments 205, 206 applied to both the upper and lower surfaces of the topsheet 200 are shown as a key feature.

[0090] As mentioned above, a surface treatment can be applied to the inner layer 200 to impart hydrophobic properties.

[0091] Thus, the inner layer 200 is a soft, comfortable, hydrophobic layer made from sustainable materials derived from plant flowers / fruits / seeds / stems that prevents moisture return and transfers liquid to the core where it is retained rather than being held adjacent to the surface of the absorbent article. Leg cuffs

[0092] As mentioned above, diaper embodiments may include a pair of leg cuffs 500 configured to effectively prevent leakage at the sides of the diaper 100. The leg cuffs keep the baby's skin dry and protected. Leg cuffs have traditionally been made of hydrophobic plastic materials such as polyethylene, polypropylene, or polyester. Like the other components, leg cuff 500 can be made from sustainable materials derived from plant flowers, fruits, seeds, or stems. Any number of sustainable materials, including those described herein, can be used to form leg cuff 500. For example, leg cuff 500 can be made from cotton (nonwoven) or other coconut materials.

[0093] Each leg cuff 500 has an associated elastic element to ensure a better fit around the leg and prevent leakage. The elastic element may or may not be made from sustainable materials derived from plant flowers, fruits, seeds, or stems. As with conventional diapers, the elastic element extends along the length of the leg cuff 500, forming a cuff gather 501 at the center of the cuff 500, as shown in FIG. 1.

[0094] It should also be appreciated that the surface treatment applied to the leg cuff layer 500 may comprise a finish that renders the sides of the leg cuff 500 hydrophobic, which would otherwise cause the leg cuff to retain moisture and not be able to transport liquid to the core and trap it away from the skin.

[0095] In some embodiments, the treatment may include Finish RPW dendrimer wax dispersion, ethoxylated alcohol-containing Nylwick (or Nylwck) modified water-dispersible polyester, Aquatek Uno sulfonated nylon, Block S sulfonated nylon, WSR XF non-fluorinated water repellent, NF-21 fluorinated (C6) surfactant, HCO16, and / or Ethox 2191. A particularly preferred form is provided as Finish Nylwck by Phoenix Chemical Company. In certain preferred embodiments, the treatment may include Permaseal WSR-XF C6 fluorocarbon and / or Flexiwet NF non-fluorocarbon silicone water repellent.

[0096] In certain embodiments, the hydrophobic treatment includes a dendrimer wax. In some of these embodiments, the treatment includes a RPW. The dendrimer waxes typically used in the present invention are available in liquid form and can be applied to nonwoven materials by many techniques known to those skilled in the art. One advantage of wax-based treatments is that the use of waxes rather than fluorocarbons reduces the environmental impact compared to fluorocarbons.

[0097] The hydrophobic treatment is applied to the natural fibers at a solids content of 0.018% to 4.75%. In some embodiments, a treatment of 0.03% to 2.85% solids is applied. In some of these embodiments, the treatment is about 0.5% by weight. In particularly preferred embodiments, the treatment is applied to the fabric at 0.02% to 3.5% by weight. It is important to apply at least a 0.018% by weight loading of the hydrophobic treatment to the leg cuff material. It has been found that the use of low levels of such ingredients allows the treated fabric to retain its hydrophilic properties, as opposed to the water resistance and repellency imparted to the fabric by high concentrations of such chemicals.

[0098] In some particularly preferred embodiments, the present invention involves applying about 2.95% by weight of a finished RPW dendrimer wax to a nonwoven cotton or cotton-elastomer blend. It is particularly useful to apply a treatment containing dendrimer wax or dendrimer wax emulsion to the inner (top) surface of the outer sheet.

[0099] Processing solutions and suspensions comprise various weight percentages of processing compositions in water unless another solvent / diluent is indicated.

[0100] External hydrophobic agents are typically applied to the surface of the nonwoven web. Internal hydrophobic agents may be mixed with the materials used to form the nonwoven web and then migrate to the surface after the nonwoven web is formed. External and internal hydrophobic agents can be characterized in the same manner as the hydrophobic agents described above with respect to their durability and wettability.

[0101] In certain preferred embodiments, the hydrophobic surface treatment includes a wax, a non-fluorocarbon water repellent, or a combination thereof. An example of a wax that can be used to treat the leg cuff layer is Finish RPW, available from Phoenix Chemical. An example of a non-fluorocarbon water repellent that can be used to hydrophobically treat the leg cuff layer is WSRXF, available from Phoenix Chemical.

[0102] It is to be understood that the foregoing is illustrative, not limiting, and that obvious modifications may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, reference should be made primarily to the appended claims, rather than the foregoing specification, to determine the scope of the invention.

Claims

1. A disposable absorbent article having an inner layer, wherein the inner layer is Natural fibers derived from the flowers, fruits, seeds, or stems of plants harvested during a single growing season, A treatment applied to at least one surface of the inner layer, with a solid content of 2.5% by weight or less, comprising a treatment containing at least one compound selected from the group consisting of wax, urethane, silicone, fluorocarbon, and non-fluorochemical water repellents, The at least one surface has a plurality of pores, Absorbent material.

2. The absorbent article according to claim 1, wherein the absorbent article is selected from the group consisting of diapers, diapers, absorbent underpants, training pants, adult incontinence products, pet incontinence products, women's hygiene products, wound dressings, and breast pads.

3. The absorbent article according to claim 1, wherein the treatment of the inner layer comprises a dendrimer wax or dendrimer wax emulsion applied to the inner layer.

4. The absorbent article according to claim 1, wherein the treatment of the inner layer comprises paraffin wax or paraffin wax emulsion applied to the inner layer.

5. The absorbent article according to claim 1, wherein the treatment of the inner layer is applied only to the upper surface of the inner layer.

6. The absorbent article according to claim 1, wherein the treatment of the inner layer is applied to the upper and lower surfaces of the inner layer.

7. The absorbent article according to claim 1, wherein the treatment of the inner layer is applied to the upper surface of the inner layer, and a hydrophilic treatment is applied to the lower surface of the inner layer.

8. The absorbent article according to claim 1, wherein the treatment is applied to the inner layer by adding 0.0015% to 1.55% by weight.

9. The absorbent article according to claim 1, further comprising a hydrophobic leg cuff.

10. A hydrophobic leg cuff containing natural fibers derived from the flowers, fruits, seeds, or stems of plants harvested during a single growing season, 4. A water-repellent treatment applied to at least one surface of the leg cuff with a solid content of 4.75% by weight or less, comprising at least one compound selected from the group consisting of wax, urethane, silicone, fluorocarbon, and non-fluorochemical water repellents. The absorbent article according to claim 1, further comprising the following:

11. The absorbent article according to claim 10, wherein the water-repellent treatment is applied to the leg cuff in an amount of 0.018% to 3.5% by weight.

12. The absorbent article according to claim 10, wherein the water-repellent treatment of the leg cuff comprises a dendrimer wax or dendrimer wax emulsion applied to any surface of the leg cuff.

13. The absorbent article according to claim 10, wherein the water-repellent treatment of the leg cuff comprises paraffin wax or paraffin wax emulsion applied to any surface of the leg cuff.

14. The absorbent article according to any one of claims 1 to 13, wherein the absorbent article is a disposable diaper.

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