Articles of manufacture comprising biodegradable absorbent materials

Abstract

The present invention provides multilayered absorbent articles of manufacture comprising one or more biodegradable absorbent layers that include without limitation a fluid-permeable top sheet; a first biodegradable absorbent layer having a superior surface in fluid communication with the fluid-permeable top sheet; a second biodegradable absorbent layer in fluid communication with and positioned inferior to the first biodegradable absorbent layer; an optional third biodegradable absorbent layer in fluid communication with and positioned inferior to the second biodegradable absorbent layer; and a barrier layer in fluid communication with and positioned inferior to the third biodegradable absorbent layer, and forming a bottom sheet having water-resistant properties; and the invention further provides methods of their manufacture.

Description

ARTICLES OF MANUFACTURE COMPRISING BIODEGRADABLE ABSORBENTMATERIALSRELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 743,979 filed December 17, 2024. The entire contents of the above-referenced application are incorporated by reference herein.FIELD OF THE INVENTION

[0002] This application relates to multilayered articles of manufacture comprising biodegradable absorbent materials.BACKGROUND

[0003] Absorbent materials are characterized by their ability to take up and retain fluids. Articles of manufacture formed from such materials exist in multiple markets. Absorbent materials used to remove and sequester undesirable liquids find applications (without limitation) in personal care products, pet care products, food packaging, health care and medical products, agricultural products, environmental cleanup, and industrial spill and waste management.

[0004] Conventional absorbent materials have been available for use in articles of manufacture for over fifty years. A key component of many conventional absorbent materials is the use of superabsorbent polymers (SAP), specialized crosslinked polymeric networks that can absorb many times their weight in liquid while themselves remaining intact in the presence of the liquid that they retain. SAPs were originally developed by the U.S. Department of Agriculture (USDA) as a soil amendment intended to improve water retention and water conservation for agricultural uses. It was discovered that early forms of SAPs were able to absorb over 400 times their weight in water, and that they tended to retain the liquid better than other types of absorbents. As private companies expanded upon the USDA research, they developed other types of SAP polymers, which were subsequently commercialized, not for agricultural purposes as the USDA originally envisioned, but for personal care items. The first products employing SAPs were disposable hygiene products for menstrual use and for adult incontinence. Use in baby diapers soon followed, and by the 1980s a myriad SAP -based products were available globally.Page l of 27

[0005] As currently produced, conventional absorbent articles of manufacture are made predominantly or entirely from synthetic materials such as SAPs, PP, PE, polyacrylates, and polyesters. SAPs in common use are typically formed synthetically from acrylate monomers. The acrylate monomers themselves are derived from petrochemical sources and are considered a non-renewable resource that is dependent on the petroleum industry, requiring significant energy input to create. Moreover, the processes required to form SAPs from the acrylate monomers are energy-intensive, entailing expense and imposing environmental burdens. Most importantly, however, SAPs are resistant to biodegradation. SAPs such as polyacrylates, polyethylene and polypropylene are non-renewable, non-biodegradable materials derived from petroleum. Products made from these materials, while offering convenient ways to deal with unwanted fluids and waste materials, impose significant burdens on the environment, mainly due to their resistance to decomposition. Synthetic plastic materials used to form conventional absorbent articles can also become fragmented into smaller, durable microplastic particles, which are known to enter waterways and land- based ecosystems, potentially affecting marine life, animal ecosystems, and human health.

[0006] One category of articles of manufacture employing synthetic absorbent materials comprises those absorbent products used for pet care. These products, used to absorb liquid waste, are typically formed as sheets or other flattened structures that can be positioned to receive and absorb urine during puppy training or from accidental elimination. They are shaped to be convenient and easy to position and dispose of; thus, they are designed to manage liquid waste effectively. The performance of these products depends on their use of materials with high absorbency, structural integrity, and leak resistance. Conventional absorbent materials such as SAPs, reinforced or combined with fluid-permeable and fluid barrier layers made from other conventional materials, commonly nondegradable and petroleum derived, provide these needed performance features.

[0007] Products manufactured for purposes like pet care can be layered to confine the liquid waste to a preselected region within the product, while permitting the influx of the liquid waste through an inner fluid-permeable layer in contact with the source of the fluid waste, and while preventing the extravasation of waste through an outer barrier layer. Materials used for each of the layers reflect the purpose of the layer itself.

[0008] The heart of a training pad product is the absorbent core. The absorbent core in a conventional product can contain combinations of SAPs for high absorbency, cellulosic materials (e.g., pulp) to provide some absorption and wicking and to stabilize the SAPswithin the core, and nonwoven synthetic materials (made from materials such as polypropylene and polyester) to maintain the structural integrity of the absorbent core and to aid in evenly distributing the liquid waste throughout the core region.

[0009] Barrier layers within and external to the absorbent core serve to prevent liquids from leaking out of the product. Such layers can be formed as thin flexible films that are relatively water impermeable, but that can be perforated or otherwise sufficiently porous to allow vapor transmission while blocking the passage of liquids. Barrier layers can combine synthetic coatings or films, and nonwoven supports to improve overall strength of the overall device and to resist tearing. The bottom sheet, facing the outside surface of the product, provides an important barrier, retaining liquids within the product’s overall structure. Thinner, more permeable barrier layers can be deployed within the product to slow the passage of liquids through the absorbent core and to decrease leakage.

[0010] In contrast to the bottom sheet, a top sheet on the surface of the product facing the source of the waste fluid, is shaped from materials that facilitate transmission of liquid from the point of discharge into the product’s absorbent core. Synthetic nonwoven fabrics, allow the passage of liquids through the top sheet while it remains dry to the touch.

[0011] Conventional materials used for pet care products such as training pads impose recognized burdens on the environment and can involve performance tradeoffs. SAPs, used for the absorbent core, are highly absorbent but non-biodegradable, as mentioned above. Cellulosic materials, often used in the absorbent core in addition to SAPs, are more amenable to biodegradability, but compared to SAPs have a lower absorption and liquid retention capacity. Thus, more of those materials is necessary if they are to replace the absorbency of SAPs, rendering the product thicker, more expensive, less comfortable to use, and more difficult to dispose of. Barrier layers made from polyethylene and similar polymers notably resist biodegradation, persisting in landfills and in the environment for centuries. Nonwoven materials that are made from polypropylene, polyester, and the like, are similarly not biodegradable, and they are recognized to contribute to microplastic pollution during manufacturing or disposal. The limitations of individual materials are compounded when they are all combined in a composite product such as a training pad. The mixed-material construction of these products, along with the waste they collect, makes them unable to be recycled, and the decomposition of the product becomes limited by the layer that takes the longest to degrade. Biodegradable alternatives have been developed for use in absorbent materials, with the goal of replacing the synthetic materials used conventionally. Althoughsubstitutes for conventional SAPs and synthetic polymers exist that are derived from natural sources, these substitutes tend not to provide the same high performance as the conventional synthetic materials.

[0012] There remains a need in the art therefore, for alternatives to conventional synthetic absorbent products that have comparable performance to synthetic materials but without having a deleterious effect on the environment. Advantageously, biodegradable absorbent materials offered as alternatives to conventional synthetic materials can replace partially or completely the synthetic materials used in mixed-material products such as pet-care training pads. Such alternatives for use in pet care products can desirably be derived from natural sources, using manufacturing processes that impose less stress on the environment. Furthermore, such alternatives are desirably biodegradable, so that they can be disposed of by natural decomposition within a manageable period of time. Also, it would be advantageous to use a natural and biodegradable superabsorbent polymer for these products that can be readily integrated into their existing manufacturing processes. A biodegradable replacement for SAPs that is compatible with manufacturing infrastructure would avoid incurring capital expenditures and would streamline the path to commercialization and disposal with less stress imposed on the environment, while providing the consumer with similar product performance as synthetic polymers.SUMMARY

[0013] Disclosed herein, in embodiments, are multilayered absorbent articles of manufacture comprising one or more biodegradable absorbent layers, comprising a fluid- permeable top sheet, a first biodegradable absorbent layer having a superior surface in fluid communication with the fluid-permeable top sheet, a second biodegradable absorbent layer in fluid communication with and positioned inferior to the first biodegradable absorbent layer, a third biodegradable absorbent layer in fluid communication with and positioned inferior to the second biodegradable absorbent layer, and a water-resistant barrier layer in fluid communication with and positioned inferior to the third biodegradable absorbent layer, and forming a bottom sheet having water-resistant properties. In embodiments, the fluid permeable top sheet is biodegradable. In embodiments, the fluid-permeable top sheet comprises skin-protective materials and can further comprise optional skin-protective additives. In embodiments, the superior surface of the first biodegradable absorbent layer is formed as a textured wicking and absorbing layer, which can be quilted, embossed, ortextured with tracks or grooves. In embodiments, the second biodegradable absorbent layer comprises an ultra-absorbent layer, which can possess wicking properties. In embodiments, the third biodegradable absorbent layer comprises a fibrous absorption-locking layer. In embodiments, wherein the first biodegradable absorbent layer and the third biodegradable absorbent are formed from the same formulation. In embodiments, there are two or more copies of the second biodegradable absorbent layer and / or the third biodegradable absorbent layer. In embodiments, one or more of the first biodegradable absorbent layer, the biodegradable absorbent layer, and the third biodegradable absorbent layer comprise up to about 20% by weight of activated carbon or activated charcoal. In embodiments, at least one layer selected from the group consisting of the first biodegradable absorbent layer, the second biodegradable absorbent layer, and the third biodegradable absorbent layer comprises fluff pulp pre-impregnated with biodegradable superabsorbent polymers, and in certain embodiments, the fluff pulp in the at least one layer is formed by processing the at least one layer in a hammermill. In selected embodiments the at least one layer in which the fluff pulp is formed by processing in the hammermill is the second biodegradable absorbent layer. In embodiments, the barrier layer exhibits grease resistance. In embodiments, the barrier layer is biodegradable.

[0014] Also disclosed herein are methods of manufacturing a multilayered absorbent article, comprising providing a fluid permeable top sheet that directs a fluid stream to contact a top biodegradable absorbent layer positioned beneath and in fluid communication with the fluid permeable top sheet; arranging one or more additional biodegradable absorbent layers beneath the top biodegradable absorbent layer and in contact with each other, wherein at least one of the one or more additional biodegradable absorbent layers is in contact with the top biodegradable absorbent layer; positioning a fluid-resistant barrier layer beneath the one or more additional biodegradable absorbent layers and in contact with at least one of the one or more additional biodegradable absorbent layers; and affixing the fluid permeable top sheet, the top biodegradable absorbent layer, the one or more additional biodegradable absorbent layers, and the bottom sheet to each other. In embodiments, each of the fluid permeable top sheet, the top biodegradable absorbent layer, the one or more additional biodegradable absorbent layers, and the bottom sheet are shaped as a flattened sheet structure.

[0015] Also disclosed herein, in embodiments, are multilayered absorbent articles of manufacture comprising an biodegradable absorbent core, wherein the biodegradableabsorbent core comprises a first biodegradable absorbent layer having a superior surface for absorbing fluid into the biodegradable absorbent core and an inferior surface for directing the fluid to the second biodegradable absorbent layer, a second biodegradable absorbent layer positioned inferior to the first biodegradable absorbent layer and structurally adapted for receiving fluid that passes through the first biodegradable absorbent layer, and a third biodegradable absorbent layer positioned inferior to the second biodegradable absorbent layer and structurally adapted for receiving fluid that passes through the second biodegradable absorbent layer. In embodiments, the biodegradable absorbent core comprises one or more additional biodegradable absorbent layers. In embodiments, the multilayered absorbent article of manufacture further comprises a fluid-permeable top sheet that directs a fluid stream into the biodegradable absorbent core and a bottom sheet comprising a barrier layer having water-resistant properties and positioned inferior to the biodegradable absorbent core. In embodiments, the barrier layer possesses grease-resistant properties. In embodiments, each of the fluid-permeable top sheet, the first biodegradable absorbent layer, the second biodegradable absorbent layer, the third biodegradable absorbent layer, and the bottom sheet is shaped as a flattened sheet structure.

[0016] Further disclosed herein are methods of manufacturing multilayered absorbent articles as described above, comprising forming a biodegradable absorbent core by affixing the bottom of the first biodegradable absorbent layer to the top of the second biodegradable absorbent layer and affixing the bottom of the second biodegradable absorbent layer to the top of the third biodegradable absorbent layer; affixing the fluid-permeable top sheet to the top of the biodegradable absorbent core; and affixing the bottom sheet to the bottom of the biodegradable absorbent core. In embodiments, the methods of manufacture further comprise forming the multilayered absorbent article using a technique selected from the group consisting of wetlaying, casting, extrusion, injection, blowing, airlaying, drylaying, spinning, rolling, pressing, molding, pelletizing, and hammermilling. In embodiments, the methods of manufacture further comprise forming the article as a sheet or as a formed article. In embodiments, the methods of manufacture further comprise subsequently processing the sheet or formed article by one or more method steps selected from the group consisting of drying methods, coating methods, molding methods, milling methods, and printing methods. In certain embodiments wherein the article is formed as a sheet, the sheet is fed into a hammermill to create a superabsorbent fluff pulp that is incorporated into one or more biodegradable absorbent layers in the biodegradable absorbent core. In certainembodiments, the article is formed as a sheet by a process selected from the group consisting of extrusion, casting, and vacuum dewatering.

[0017] Additionally encompassed are multilayered absorbent articles of manufacture comprising one or more biodegradable absorbent layers, comprising a fluid-permeable top sheet, a first biodegradable absorbent layer having a superior surface in fluid communication with the fluid-permeable top sheet, a second biodegradable absorbent layer in contact with the first biodegradable absorbent layer, a third biodegradable absorbent layer in contact with the second biodegradable absorbent layer, and a barrier layer positioned inferior to the third biodegradable absorbent layer forming a bottom sheet. In embodiments, the fluid permeable top sheet is biodegradable. In embodiments, a superior surface of the first biodegradable absorbent layer is textured. In embodiments, wherein the first biodegradable absorbent layer and the third biodegradable absorbent are formed from the same formulation. In embodiments, there are two or more copies of the second biodegradable absorbent layer and the third biodegradable absorbent layer. In embodiments, the barrier layer exhibits water resistance. In embodiments, the barrier layer is biodegradable.BRIEF DESCRIPTION OF THE FIGURES

[0018] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

[0019] FIG. 1 depicts schematically a cross-section of a multilayered article of manufacture consistent with the principles of the invention.

[0020] FIG. 2 is a photograph showing the layers of a multilayered article of manufacture consistent with the principles of the invention.DETAILED DESCRIPTION

[0021] Absorbent products in the prior art used for pet care and other purposes have been formed with only a single absorbing layer. With only a single absorbing layer however, the only variable available for tuning is the absorption capacity of the layer itself. The single absorbent sheet may have to be made thicker to provide sufficient absorption, which makes the sheet harder to manipulate during the manufacturing process.

[0022] Advantageously, the article of manufacture disclosed herein can employ multiple sheets in its design. These multiple sheets can be made thinner and stacked to obtain the desired absorbency, in contrast to a single thick absorbent sheet layer. The basic design of a training pad in accordance with the principles of the invention is a multilayered structure having one or more biodegradable layers forming a biodegradable absorbent core, enclosed by a fluid-permeable top layer and a bottom barrier layer. The top layer and the bottom layer can be made of biodegradable materials as disclosed herein, resulting in a fully biodegradable product. In embodiments, the product can comprise a biodegradable absorbent core and be adapted for combination with a conventional top sheet and / or bottom sheet. This biodegradable core can include fluff pulp that has been pre-impregnated with biodegradable superabsorbent polymers, a sheet or mass of biodegradable superabsorbent polymers, or a composite sheet or mass of biodegradable polymers and biodegradable ingredients such as natural fillers. These natural fillers can comprise natural inorganic fillers, polysaccharides and derivatives thereof, such as (without limitation) starch or cellulose, e.g., cellulose in the form of pulp fibers.

[0023] Layering the components of the biodegradable core offers more flexibility for customizing the absorption that it provides. In embodiments, the biodegradable core of the training pad as disclosed herein can comprise a plurality of fibrous absorbent sheets, which can be made from the same or different materials. The presence of multiple sheets allows them to be varied and tailored in thickness and in composition to meet the particular needs of the product. In embodiments, an ultrawicking absorption sheet or a spray-dried powder layer can be provided as an additional layer in the biodegradable core. Biodegradable absorbent materials can be formed as particles, fibers, or beads and airlaid into a cellulosic matrix such as fluff pulp. Other fibrous materials can be similarly used to suspend, structure, or otherwise support embedded particles of biodegradable superabsorbent materials.

[0024] As described herein, each of the multiple sheets has a top (superior) and bottom (inferior) surface. The top surface and the bottom surface of a sheet can have the same or similar properties, or different properties in accordance with its function. The fluid waste is deposited on the superior surface of the top sheet and then passes through the multiple layers as described above in more detail.

[0025] The top layer or top sheet is fluid permeable, and is in contact with the source of the fluid waste. The fluid encounters the top surface of this top sheet layer and passes through this top layer to encounter the biodegradable core. Advantageously, this top layer can bemore hydrophobic than the first absorbent layer to drive the fluid into the absorbent layers, but not so hydrophobic that it prevents fluid traversal through the layer at the desired rate. The fluid waste then passes through some or all of the biodegradable core layers as described below. Any fluid waste that passes through the biodegradable core layers without being completely absorbed then encounters the bottom layer. The bottom layer provides a barrier to prevent the leakage of fluid that is incompletely absorbed and retained in the biodegradable core layers, and that therefore passes through or extravasates from the biodegradable core. The bottom layer is water-resistant and may have additional oil-resistant properties.

[0026] The layered structure of an exemplary absorbent article (here, a training pad) manufactured in accordance with the principles of the invention is depicted in cross-section in FIG. 1. FIG. 1 shows schematically a multilayered pet care training pad 100. This Figure shows a fluid deposit 114 directed at the top layer 102 of the pad 100. This layer 102 may come in contact with the skin surface of the animal, so can comprise skin-protective materials, for example can be made in whole or in part of a skin-protective material that is gentle on delicate structures, or can form its superior surface from such skin-protective materials. This top layer 102 can include optional skin-protective additives to protect the skin further. The top layer 102 is permeable to fluid rather than absorptive, and serves to direct the fluid 114 into the absorbent core 106.

[0027] The absorbent core 106 depicted in the Figure comprises three absorbent layers: a quilted or textured top wi eking and absorbing layer 104, an ultra-absorbent layer having moisture-locking behavior, optionally possessing wi eking properties 108, and an optional additional fibrous absorption-locking layer 110. In embodiments, the textured top absorbing layer 104 has a textured surface that features textural elements to expand the surface area for absorption, for example tracks or grooves that facilitate the ingress of the fluid, that enhance wi eking and liquid spread across the surface, and / or that resist liquid runoff by directing the liquid with its texture. In embodiments, the fibrous absorption-locking layer 110 can be formed from the same formulation as the textured top absorbing layer 104, with or without the textural elements. In embodiments, the middle-most layer 108 is less wi eking than the top and lower fibrous layers 104 and 110. Suitable formulations for each of these layers are described below in more detail. As shown in this Figure, the fluid 114 passes through the top layer 102 and into and potentially through the absorbent core 106, but is prevented from egress by the bottom barrier layer 112, which possesses water-resistant and optionallygrease-resistant properties. All of the layers shown in FIG. 1 are desirably made of biodegradable materials. However, it is understood that the top layer 102 or the bottom layer 112 can be replaced by conventional materials if this is more advantageous economically, albeit with a loss of complete biodegradability.

[0028] The layers of training pad shown schematically in FIG. 1 are depicted in the photograph of FIG. 2. As shown in FIG. 2, the training pad 200 comprises five layers. The top layer 202 is permeable to fluid, allowing the fluid (not shown) to penetrate the pad 200 and become absorbed in the layers of the absorbent core. These layers, as shown in FIG. 2, are the same as those represented schematically in FIG. 1 : the quilted or textured top absorbing and / or wicking layer 204, the ultra-absorbent layer 208, and the absorptionlocking layer 210. A bottom barrier layer 212 possesses water-resistant and optionally grease-resistant properties.

[0029] While the Figures above show three layers forming the absorbent core, it is understood that the absorbent core can comprise fewer or more layers than those shown, and that the layers can be arranged in the depicted arrangement or in any other arrangement, based on the desired absorbent properties and product handling properties. For example, and without limitation, the ultra-absorbing layer 108 / 208 and the fibrous absorbent and wicking layer 110 / 210 can be added to the construction multiple times for increased absorption capacity. This would yield a multilayered structure having the following layers:• Nonwoven top layer• Quilted fibrous wicking absorbing layer• Ultra absorbing / gelling layer• Fibrous (optionally quilted) absorbing layer• Ultra absorbing / gelling layer• Fibrous absorbing layer• Bottom layer

[0030] In a preferred embodiment, the quilted / textured top layer 104 / 204 remains closest to the fluid-permeable top layer 102 / 202, while the lower absorbent layers 108 / 208 and 110 / 210 are disposed beneath it. Other arrangements can be readily envisioned by skilled artisans using no more than routine experimentation.

[0031] Formulations for the various absorbent layers shown in the foregoing figures are presented below.

[0032] Formulations for materials forming the fibrous absorbing layers (textured and nontextured) can include, without limitation, the following ingredients at the noted ranges (unless otherwise designated, all percentages are by weight). Filler polysaccharide such asstarch, modified starch, alginates, or cellulose such as pulp such as bagasse, eucalyptus, bamboo, hemp, sisal, kenaf, cotton, cotton linters, softwood, hardwood, jute, reed, abaca, straw, and the like can be included at about 40% to about 95% by weight. Hydroxyethyl cellulose can be included at about 1 to about 50% by weight. Sodium carboxymethylcellulose can be included at about 0 to about 50% by weight. Hydroxypropyl methylcellulose can be included at about 0% to about 12.5% by weight. Xanthan gum can be included at about 0% to about 15% by weight. Particulate filler such as without limitation, wood flour, saw dust, and natural inorganic fillers such as calcium carbonate, bentonite, montmorillonite, kaolin, and the like can be loaded at about 0% to about 60% by weight. Activated carbon / charcoal for odor absorption can be added at about 0% to about 20% by weight. Microfibrillated and / or nanofibrillated cellulose can be added at about 0% to about 20% by weight. Capryl glucoside can be added at about 0.5 to about 25% by weight. Glycerol can be added at about 0.1 to about 15% by weight. Citric acid utilized to link the cellulose polymers can optionally be added at about 0% to about 20% by weight. Animal attractants can also be added.

[0033] In embodiments, formulations such as those listed below can be prepared:• Formulation 1Filler pulp (e.g., bagasse, eucalyptus, or the like): 7.5g HEC (hydroxyethyl cellulose) (1.3M Mw): 0.686g HPMC (hydroxypropyl methylcellulose) (120,000 Mw): 0.172g Capryl Glucoside: 0.572gSoftwood kraft pulp (4% solid suspension in water): 0.386 (dry weight)Valida L nanofibrillated cellulose (NFC) / microfibrillated cellulose (MFC) (3% solid suspension in water): 0.1g (dry weight) Saw dust (optional): 0.042g Glycerol: 0.042g• Formulation 2Filler pulp (used bagasse, eucalyptus, or the like): 15g HEC (1.3M Mw): 0.686g HPMC (120,000 Mw): 0.172g Capryl Glucoside: 0.572gSoftwood kraft pulp (4% solid suspension in water): 0.386 (dry weight)Valida L NFC / MFC (3% solid suspension in water): 0.1g (dry weight) Saw dust (optional): 0.042g Glycerol: 0.042g• Formulation 3Filler pulp (e.g., bagasse, eucalyptus, or the like): 6gHEC (hydroxyethyl cellulose) (1.3M Mw): 0.686gHPMC (hydroxypropyl methylcellulose) (120,000 Mw): 0.172gCapryl Glucoside: 0.572gSoftwood kraft pulp (4% solid suspension in water): 0.386 (dry weight)Valida L nanofibrillated cellulose (NFC) / microfibrillated cellulose(MFC) (3% solid suspension in water): 0.1g (dry weight)Saw dust (optional): 0.042gGlycerol: 0.042g• Formulation 4Filler pulp (e.g., bagasse, eucalyptus, or the like): 5gHEC (hydroxyethyl cellulose) (1.3M Mw): 0.686gHPMC (hydroxypropyl methylcellulose) (120,000 Mw): 0.172gCapryl Glucoside: 0.286gSoftwood kraft pulp (4% solid suspension in water): 0.386 (dry weight)Valida L nanofibrillated cellulose (NFC) / microfibrillated cellulose(MFC) (3% solid suspension in water): 0.1g (dry weight)Saw dust (optional): 0.042gGlycerol: 0.042g• Formulation 5Filler pulp (e.g., bagasse, eucalyptus, or the like): 6gHEC (hydroxyethyl cellulose) (1.3M Mw): 0.686gNaCMC (sodium carboxymethyl cellulose): 0.172gCapryl Glucoside: 0.572gSoftwood kraft pulp (4% solid suspension in water): 0.386 (dry weight)Valida L nanofibrillated cellulose (NFC) / microfibrillated cellulose(MFC) (3% solid suspension in water): 0.1g (dry weight)Saw dust (optional): 0.042gGlycerol: 0.042g• Formulation 6Filler pulp (e.g., bagasse, eucalyptus, or the like): 6gHEC (hydroxyethyl cellulose) (1.3M Mw): 0.172gNaCMC (sodium carboxymethyl cellulose): 0.686gCapryl Glucoside: 0.572gSoftwood kraft pulp (4% solid suspension in water): 0.386 (dry weight)Valida L nanofibrillated cellulose (NFC) / microfibrillated cellulose (MFC) (3% solid suspension in water): 0.1g (dry weight) Saw dust (optional): 0.042g Glycerol: 0.042g• Formulation 7Filler pulp (e.g. bagasse, eucalyptus, or the like): 7.5g HEC (1.3M Mw): 0.686g HPMC (120,000 Mw): 0.172g Xanthan gum: 0.05g Capryl Glucoside: 0.572gFluff pulp (4% solid suspension in water): 0.386 (dry weight) Valida L NFC / MFC (3% solid suspension in water): 0.1g (dry weight) Glycerol: 0.042g Saw dust (optional): 0.042g

[0034] In embodiments, formulations for materials forming an ultra-absorbing layer can include, without limitation, the following ingredients at the noted ranges (unless otherwise designated, all percentages are by weight). Filler polysaccharides such as starches, modified starches, alginates, or celluloses (such as pulp such as bagasse, eucalyptus, bamboo, hemp, sisal, kenaf, cotton, cotton linters, softwood, hardwood, jute, reed, abaca, straw, and the like) can be included at about 0% to about 80% by weight. Hydroxyethyl cellulose can be included at about 5 to about 99% by weight. Sodium carboxymethylcellulose can be included at about 0% to about 90% by weight. Hydroxypropyl methylcellulose can be included at about 0% to about 25% by weight. Methylcellulose can be included at about 0% to about 50% by weight. Xanthan gum can be included at about 0% to about 25% by weight. Particulate fillers such as, without limitation, wood flour, saw dust, and natural inorganic fillers such as calcium carbonate, bentonite, montmorillonite, kaolin, and the like can be loaded at about 0% to about 60% by weight. Activated carbon / charcoal for odor absorption can be added at about 0% to about 20% by weight. Microfibrillated cellulose and / or nanofibrillated cellulose can be added at about 0% to about 50% by weight. Capryl glucoside can be added at about 0.5 to about 25% by weight. Glycerol can be added at about 0.1 to about 15% by weight. Citric acid utilized to link the cellulose polymers can optionally be added at about 0% to about 20% by weight. Animal attractants can also be added.

[0035] In embodiments, formulations such as those listed below can be prepared:• Formulation 8HEC (1.3M Mw): 0.686gHPMC (120,000 Mw): 0.172gCapryl Glucoside: 0.572gSoftwood kraft pulp (4% solid suspension in water): 0.386 (dry weight)Valida L NFC / MFC (3% solid suspension in water): 0.1g (dry weight)Saw dust (optional): 0.042gGlycerol: 0.042g• Formulation 9HEC (1.3M Mw): 0.686gHPMC (120,000 Mw): 0.172gCapryl Glucoside: 0.572gValida L NFC / MFC (3% solid suspension in water): 0.1g (dry weight)Glycerol: 0.042g• Formulation 10HEC (1.3M Mw): 0.686gHPMC (120,000 Mw): 0.172gCapryl Glucoside: 0.572gGlycerol: 0.042g• Formulation 11HEC (1.3M Mw): 0.686gHPMC (120,000 Mw): 0.172gCapryl Glucoside: 0.286gGlycerol: 0.042g• Formulation 12HEC (1.3M Mw): 0.686gNaCMC: 0.172gCapryl Glucoside: 0.1gGlycerol: 0.042g• Formulation 13HEC (1.3M Mw): 0.172gNaCMC: 0.686gCapryl Glucoside: 0.1gGlycerol: 0.042g• Formulation 14HEC (1.3M Mw): 3g NaCMC: 1g Citric Acid: 0.2gGlycerol: 0.1g• Formulation 15HEC (1.3M Mw): 1gNaCMC: 3g Citric Acid: 0.2g Glycerol: 0.1g• Formulation 16HEC (1.3M Mw): 0.686g HPMC (120,000 Mw): 0.172g Xanthan gum: 0.05g Capryl Glucoside: 0.572g Fluff pulp (4% solid suspension in water): 0.386 (dry weight) Valida L NFC / MFC (3% solid suspension in water): 0.1g (dry weight) Glycerol: 0.042g Saw dust (optional): 0.042g

[0036] In embodiments, formulations for materials forming the bottom layer can include, without limitation, the following ingredients at the noted ranges (unless otherwise designated, all percentages are by weight). Cellulose derivates such as (but without limitation) cellulose acetate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose acetate propionate, hydroxypropyl methylcellulose acetate succinate, cellulose nitrate, ethyl cellulose, sodium carboxymethyl cellulose, carboxymethyl cellulose, cellulose salts, methyl cellulose, hydroxypropyl methylcellulose, and hydroxypropyl cellulose, chitosan, alginates, and starches can be added at about 5 to about 99% by weight, or in lower amounts such as about 5 to about 98% by weight, about 5 to about 97% by weight, about 5 to about 96% by weight, about 5 to about 95% by weight, about 5 to about 94% by weight, about 5 to about 93% by weight, about 5 to about 92% by weight, about 5 to about 91% by weight, and about 5 to about 90% by weight. Nanofibrillated and / or microfibrillated cellulose can be added at about 5 to about 99% by weight, or in lower amounts such as about 5 to about 98% by weight, about 5 to about 97% by weight, about 5 to about 96% by weight, about 5 to about 95% by weight, about 5 to about 94% by weight, about 5 to about 93% by weight, about 5 toabout 92% by weight, about 5 to about 91% by weight, and about 5 to about 90% by weight . Natural crosslinking agents such as citric acid, succinic acid, tartaric acid, maleic acid, glutamic acid, glycolic acid, tannic acid, epigallocatechin gallate, genipin, vanillin, urea, polycarboxylic acids, polyphenols, and the like can be added at about 0% to about 25% by weight. Natural waxes such as beeswax and the like, gum rosin, rosin derivates, the acids that comprise gum rosin such as abietic acid, pimaric acid, palustric acid, dehydroabietic acid, and all derivatives thereof can be added at about 2.5 to about 99% by weight. Plasticizers such as, but without limitation, polyols such as glycerol, xylitol, sorbitol, mannitol, maltitol, and the like, acetyl triethyl citrate, triethyl citrate, tributyl citrate, acetyl tributyl citrate, and the like, polyethylene glycol (PEG), polyethylene oxide (PEO), fatty acids such as oleic, stearic, dimer acids and the like can be added at about 0.1 to about 25% by weight.

[0037] In embodiments, formulations such as those listed below can be prepared:• Formulation 17CAB (70,000 Mw): 40g Rosin: 15gAcetyl tri ethyl citrate (TEA): 6g• Formulation 18CAB (70,000 Mw):40g Rosin: 15g tri ethyl citrate (TEC): 6g Acetone 300g• Formulation 19Microfibrillated and / or nanofibrillated cellulose: 10gNaCMC: 1gRosin: 5gGlycerol: 0.5g• Formulation 20Microfibrillated and / or nanofibrillated cellulose: 10gNaCMC: 1gRosin: 5gGlycerol: 0.5gCitric acid: 0.1g

[0038] Absorbent articles consistent with the principles of the invention can be manufactured as follows.

[0039] The various layers are formed first. Forming the fluid-permeable nonwoven sheet is known in the art as typical nonwoven wet laid manufacturing process. Forming the fibrous sheet and absorbing sheets involved the following steps: a) Dry mixed the following as powders HEC and HPMC, optionally including xanthan gum. b) Measured 100g of hot water (80°C) and added surfactant (capryl glucoside) and plasticizer (glycerol). c) Added dry mixed powders to the liquid from Step (b), and allowed them to mix until the solution cools below 40°C and powders are fully solubilized. Optionally added saw dust and mix. d) Added 0.1g (dry weight) of 3% Valida NFC (3.33g of 3% NFC). e) Then added 0.386g (dry weight) of 4% pulp (9.65g). When producing a fibrous sheet, 7.5g (dry weight) of filler pulp was added. In one example, 37.5g of 20% solid bagasse was added for this purpose. f) The solution was allowed to mix until well combined and then was aerated. For aeration an IKA T25 overhead homogenizer was used. In one example, the solution was homogenized for ~5 minutes at 10,000-15,000 rpm. g) A number of methods can be used for shaping the solution as prepared above into desirable final forms for the final absorbent produce. The finalized solution can be cast out using a doctor blade, slot, slit, or manifold die, or using other methods known in the art. The final solution can also be spray dried into beads / particulates. The final solution can also be pastillated or molded. If more water is used at the beginning of the process, so that the final solids content of the formulation is around 0.5%, then the formulation can be vacuum dewatered and further dried following typical procedures of paper manufacturing processes. The resultant dried sheet can be used as is or fed into a hammermill to make a fluff pulp to be used as an absorbent layer.

[0040] In another example, forming the barrier layer involved the following steps: a) Solvent Cast: 300g of acetone was used as the starting solvent, to which was added 6g of TEA. 15g of gum rosin was then added, and was mixed in until solubilized. 40g of cellulose acetate butyrate (CAB) was then added, and wasmixed in until solubilized. Sheets were then cast out at a desired thickness (0.1mm-5mm). b) For sheet extrusion, CAB, rosin, and TEA were fed into the extruder at a ratio of 40: 15:6, and extruded through a slit die to produce sheets.

[0041] Forming the final absorbent product was performed as follows: a) Two fully dried fibrous absorbing sheets, one gelling / ab sorbing sheet, and one barrier layer were collected. b) A bio-based adhesive was produced: 5g of methyl cellulose was solubilized in 95g of water and 1.67g (dry weight) of 3% NFC was added. c) Separately 6.67g of rosin was solubilized in 66.7g of ethanol. The two solutions were combined and mixed until homogeneous. d) The resulting formulation was used as a glue on the edges of each layer to adhere them together. e) The final product was hot pressed to quickly fuse the layers and dry the glue. f) Synthetic or biobased glues / binders known in the art can also be used to adhere the layers. The base / barrier layer can also be folded around the edges of the pad and hot pressed to seal the pad without the addition of an adhesive.

[0042] Techniques for forming the formulations described above into articles of manufacture can also include wetlaying, casting, extrusion, injection, blowing, airlaying, drylaying, spinning, rolling, pressing, molding, pelletizing, hammermilling, or combinations thereof, and any other methods familiar to those of skill in the art. In one embodiment, sheets can be formed by techniques such as extrusion, for example by mixing the precursor material in a homogenizer or an extruder, and feeding the formulation into a slot die. The sheet form factor is especially suitable for petcare purposes such as training pads. The resulting sheets or articles can be further processed: for example, they may undergo drying methods (convection, microwave, steel belt), coating methods (spray-on, roll-on, lamination,) molding methods (i.e. thermoforming, pressing, perforation, shaping, forming), milling methods (hammermilling), printing methods, and the like. In embodiments, the fibrous absorbent sheets are fed into a hammermill to create a superabsorbent fluff pulp that is incorporated into one or more biodegradable absorbent layers in the biodegradable absorbent core.

[0043] In certain embodiments the formulations described above can be further processed to mimic the size, shape, density, and / or absorption characteristics of superabsorbentpolymer (SAP) beads such as sodium polyacrylate beads, providing a replacement for SAPs in current manufacturing equipment, such as the specialized diaper air laying machines. In embodiments, for example, the formulation can be sized in sizes that are similar to SAP beads used in absorbent products like diapers, having a size range from about 0.1 to about 10 mm, for example, about 100 to about 900 micrometers, which can be foamed or not foamed. Such biobased beads can be used with conventional equipment used to form certain types of petcare products, including training pads.

[0044] Without being bound by theory, it is envisioned that the fibers of any size (including without limitation microfibrillated and / or nanofibrillated cellulose) or fillers of any size selected for strengthening purposes can, as ingredients in the absorbent materials described herein, reinforce such materials by filling in pores or gaps within their substrate matrices, thus distributing mechanical loads more effectively and providing additional load-bearing points, thereby increasing the strength of the overall composite. Fibers, such as short stiff fibers like microfibrillated and / or nanofibrillated cellulose or cotton linters, long thicker fibers such softwood pulp, or kinked / spring like fibers and structures can also be selected for strengthening an absorbent material by creating or lending structure (and therefore strength) to a pre-existing matrix that has been produced in a foamed or porous material. Besides adding strength to such a material, fillers and fibers can also absorb and dissipate energy from impacts, making a layer or an article of manufacture less prone to fracture and fragmentation, and / or stronger when wetted. Thus, the incorporation of fibers or fillers as performance-improving additives can provide sufficient strength to a foamed or porous or otherwise low-density material to allow such a material to be useful for absorbency.

[0045] Surfactants can act to lower wetting time and as foaming agents to help encourage a lower density structure, especially when subjected to high shear mixing and aeration. Examples of surfactants and plasticizers include, without limitation, glucosides (capryl , hexyl, lauryl, decyl, coco, and the like), alkyl polyglucosides like GLUCOPON®, polysorbate, polyethylene glycol, polypropylene glycol, PEG / PPG coblock polymers and the like, triglycerin, polyols (glycerol, xylitol, mannitol, sorbitol, maltitol, and the like), polyoxyethylene sorbitans (monopalmitate, monostearate, monooleate, and the like), cocamides (monoethanolamine and diethanolamine), sulfates (sodium coco, sodium dodecyl, sodium lauryl, sodium laureth, sodium octyl, ammonium lauryl, ammonium laureth), sodium lauroyl sarcosinate, sodium caprylyl sulfonate, sodium cocoyl isethionate, Cl 0-16 Pareth, and the like.

[0046] As an example of an arrangement using foaming technology, a low density, foamed absorbent composite material having a matrix comprising a mixture of softwood and hardwood pulp, cellulose nano and / or microfibers, can be prepared from water-swellable polymeric materials, such as, without limitation, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose, methylcellulose, alginates, carrageenan, gums, water-swellable polysaccharides, and / or any combination thereof. In embodiments, nanoscale fibers such as cellulose nanofibers and cellulose microfibers and nanoscale fillers, such as nanocellulose elements, lignin, mineral powders, nanoclays such as montmorillonite and nano-sized silica, are performance-improving additives that can add significant reinforcement to the foamed bioabsorbent formulations, and improve the strength thereof, due to the high surface area and aspect ratio of these nanoscale materials.EXAMPLES

[0047] Example 1

[0048] Two mixtures (Mixture 1 and Mixture 2) were prepared, molded and baked to form samples for testing. The preparation of the two mixtures, described below, was the same until the step (2 and 4) where the bagasse was added. Mixture 1 had a bagasse fiber loading of 88% (on dry weight basis), and an absorbing polymer loading of 5%, while Mixture 2 had a bagasse fiber loading of 79% (on dry weight basis) and an absorbing polymer loading of 9%. As described below, an absorbing solution (2g dry weight mixture of HEC, HPMC, softwood kraft, saw dust, NFC, capryl glucoside, and glycerol in 98g of water) was prepared and combined with 15g (dry weight) of bagasse in Mixture 1. The same absorbing solution was prepared again and combined with 7.5g (dry weight) of bagasse in Mixture 2. Both Mixtures had the same amount of the absorbing solution and its components; the only difference between the two mixtures was the quantity of bagasse fiber added. The samples produced from each of the mixtures prepared according to the methods of this Example were then evaluated for absorption and density, the results of which are set forth in Table 1 below.

[0049] For both Mixtures (Mixture 1 and Mixture 2), Step 1 was carried out as follows to prepare the absorbing solution:• 98g of water was heated to 70°C, and 0.572g of capryl glucoside, and 0.042g of glycerol were added to the hot water while mixing. Then, 0.686g of HEC (1,300,00 Mw) and 0.172g of HPMC (120,000 Mw) were dry-mixed andadded to this hot aqueous solution. Once the solution cooled and the absorbing polymers were well solubilized, 3.33g of 3% Valida L NFC (0.1g dry weight) was added and mixed until well incorporated (no clumps). Then 9.65g of 4% softwood kraft pulp (0.386g dry weight) was added, followed by 0.042g of sawdust. This combination yielded an absorbing solution containing 2 g (dry weight) of the additives (capryl glucoside, glycerol, HEC, HPMC, NFC, softwood kraft pulp, and sawdust) per 100 g of the solution. This absorbing solution was then combined with bagasse to prepare Mixture 1 and Mixture 2.

[0050] To produce samples from Mixture 1, Steps 2 and 3 were performed:• Step 2: 50g of a 30% solids bagasse formulation (i.e., a formulation of 30% bagasse solids and 70% water, with 50g of the formulation yielding 15g dry weight bagasse) was mixed with 100 g of the absorbing solution that was prepared in Step 1, using a T25 overhead IKA homogenizer at ~15,000rpm. This yielded Mixture 1.• Step 3: Mixture 1 was then spread into silicone molds, and baked at 85°C in the oven until dry.

[0051] To produce samples from Mixture 2, Step 1 was repeated, and then Steps 4 and 5 were performed.• Step 4: 25g of the 30% solids bagasse formulation described above (yielding 7.5g dry weight bagasse) was mixed with the 100g of the absorbing solution that was prepared in Step 1, using a T25 overhead IKA homogenizer at ~15,000rpm. This yielded Mixture 2.• Step 5: Mixture 2 was then spread into silicone molds, and baked at 85°C in the oven until dry.• Step 6: Mixture 2 was also cast into sheets at a wet thickness of 6mm using a doctor blade. These sheets were dried at 85°C on a sheet pan and later fed into a W6H Schutte Hammermill, to create a fluff pulp impregnated with biodegradable superabsorbent polymers.

[0052] The resulting molded dry final absorbing articles were both relatively low density as compared to other absorbent products. However, the formulation with the lower bagasse fiber content was more easily mixed and aerated using the homogenizer, had the lower average density (-0.055 g / cc as opposed to 0.095 g / cc), and had the higher average (weightnormalized) absorption multiplier (~15 times its weight in water as opposed to ~11 times its weight in water). The absorption multiplier was calculated using the following equation:Water Absorption Multiplier = (Final weight - Initial weight) / Initial weightUsing these parameters, the samples produced according to the methods of this Example were 5 evaluated for absorption and density. The results are set forth in Table 1 below.TABLE 1

[0002] While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various5 changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. All United States patents and published or unpublished United States patent applications cited herein are incorporated by reference. All published foreign patents and patent applications cited herein are hereby incorporated by reference. All other published references, documents, manuscripts and scientific literature 0 cited herein are hereby incorporated by reference. The relevant teachings of all patents, published applications, and references cited herein are incorporated by reference in their entirety.

Claims

CLAIMS1. A multilayered absorbent article of manufacture comprising one or more biodegradable absorbent layers, comprising: a fluid-permeable top sheet; a first biodegradable absorbent layer having a superior surface in fluid communication with the fluid-permeable top sheet; a second biodegradable absorbent layer in fluid communication with and positioned inferior to the first biodegradable absorbent layer; an optional third biodegradable absorbent layer in fluid communication with and positioned inferior to the second biodegradable absorbent layer; and a water-resistant barrier layer in fluid communication with and positioned inferior to the third biodegradable absorbent layer, and forming a bottom sheet having water-resistant properties.

2. The multilayered absorbent article of claim 1, wherein the fluid-permeable top sheet is biodegradable.

3. The multilayered absorbent article of claim 1, wherein the fluid-permeable top sheet comprises skin-protective materials.

4. The multilayered absorbent article of claim 3, wherein the fluid-permeable top sheet further comprises optional skin-protective additives.

5. The multilayered absorbent article of claim 1, wherein the fluid-permeable top sheet is more hydrophobic than the first biodegradable absorbent layer.

6. The multilayered absorbent article of claim 1, wherein the first biodegradable absorbent layer is formed as a textured wicking and absorbing layer.

7. The multilayered absorbent article of claim 1, wherein the superior surface of the textured wicking and absorbing layer is quilted, embossed, or is textured with tracks or grooves.

8. The multilayered absorbent article of claim 1, wherein the second biodegradable absorbent layer comprises an ultra-absorbent layer.

9. The multilayered absorbent article of claim 8, wherein the ultra-absorbent layer possesses wicking properties.

10. The multilayered absorbent article of claim I, wherein the third biodegradable absorbent layer comprises a fibrous absorption-locking layer.

11. The multilayered absorbent article of claim 1, wherein the barrier layer possesses greaseresistant properties.

12. The multilayered absorbent article of claim 1, wherein the barrier layer is biodegradable.

13. The multilayered absorbent article of claim 1, wherein the first biodegradable absorbent layer and the third biodegradable absorbent are formed from the same formulation.

14. The multilayered absorbent article of claim 1, wherein one or more of the first biodegradable absorbent layer, the biodegradable absorbent layer, and the third biodegradable absorbent layer comprise up to about 20% by weight of activated carbon or activated charcoal.

15. The multilayered absorbent article of claim 1, wherein at least one layer selected from the group consisting of the first biodegradable absorbent layer, the second biodegradable absorbent layer, and the third biodegradable absorbent layer comprises fluff pulp preimpregnated with biodegradable superabsorbent polymers.

16. The multilayered absorbent article of claim 15, wherein the fluff pulp in the at least one layer is formed by processing the at least one layer in a hammermill.

17. The multilayered absorbent article of claim 16, wherein the at least one layer is the second biodegradable absorbent layer.

18. The multilayered absorbent article of claim 1, wherein the first biodegradable absorbent layer and the third biodegradable absorbent layer are formed from the same formulation.

19. The multilayered absorbent article of claim 1, comprising at least two copies of at least one of the second biodegradable layer and third biodegradable absorbent layer.

20. A multilayered article of manufacture, comprising a biodegradable absorbent core, wherein the biodegradable absorbent core comprises: a first biodegradable absorbent layer having a superior surface for absorbing fluid into the biodegradable absorbent core and an inferior surface for directing the fluid to the second biodegradable absorbent layer; a second biodegradable absorbent layer positioned inferior to the first biodegradable absorbent layer and structurally adapted for receiving fluid that passes through the first biodegradable absorbent layer; and a third biodegradable absorbent layer positioned inferior to the second biodegradable absorbent layer and structurally adapted for receiving fluid that passes through the second biodegradable absorbent layer.

21. The multilayered absorbent article of manufacture of claim 20, wherein the biodegradable absorbent core comprises one or more additional biodegradable absorbent layers.

22. The multilayered absorbent article of manufacture of claim 20, further comprising a fluid- permeable top sheet that directs a fluid stream into the biodegradable absorbent core, and a bottom sheet comprising a barrier layer having water-resistant properties and positioned inferior to the biodegradable absorbent core.

23. The multilayered absorbent article of manufacture of claim 22, wherein the barrier layer possesses grease-resistant properties.

24. The multilayered absorbent article of claim 22, wherein each of the fluid-permeable top sheet, the first biodegradable absorbent layer, the second biodegradable absorbent layer, the third biodegradable absorbent layer, and the bottom sheet is shaped as a flattened sheet structure.

25. A method of manufacturing the multilayered absorbent article of claim 22, comprising: forming a biodegradable absorbent core by affixing the bottom of the first biodegradable absorbent layer to the top of the second biodegradable absorbent layer and affixing the bottom of the second biodegradable absorbent layer to the top of the third biodegradable absorbent layer; affixing the fluid-permeable top sheet to the top of the biodegradable absorbent core; and affixing the bottom sheet to the bottom of the biodegradable absorbent core.

26. The method of claim 25, further comprising forming the multilayered absorbent article using a technique selected from the group consisting of wetlaying, casting, extrusion, injection, blowing, airlaying, drylaying, spinning, rolling, pressing, molding, pelletizing, and hammermilling.

27. The method of claim 25, further comprising forming the article as a sheet or as a formed article.

28. The method of claim 27, further comprising subsequently processing the sheet or formed article by one or more method steps selected from the group consisting of drying methods coating methods, molding methods, milling methods, and printing methods.

29. The method of claim 27, wherein the article is formed as a sheet, and wherein the sheet is fed into a hammermill to create a superabsorbent fluff pulp that is incorporated into one or more biodegradable absorbent layers in the biodegradable absorbent core.

30. The method of claim 27, wherein the article is formed as a sheet by a process selected from the group consisting of extrusion, casting, and vacuum dewatering.

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