Patent application title: SMALL ANIMAL BEDDING MATERIAL
Eileene E. Keating (Kennesaw, GA, US)
GEORGIA-PACIFIC WOOD PRODUCTS LLC
IPC8 Class: AD21C300FI
Class name: Processes of chemical liberation, recovery or purification of natural cellulose or fibrous material gas, vapor or mist contact steam only
Publication date: 2012-01-05
Patent application number: 20120000620
A fibrous material for small animal bedding material and methods for
making the same. The fibrous material can be or include a plurality of
lignocellulosic fibers derived from wood-based materials. The wood-based
material can be a mixture of hardwoods and/or softwoods that are
processed into individual fibers having varying lengths to form a matrix
of fibers that is soft enough for small animal bedding, but rigid enough
to maintain nest or burrow shape integrity after being created by the
1. A method for making small animal bedding, comprising: preparing and
filtering an initial wood mixture; softening the initial wood mixture in
a steam digester to produce a softened material; defiberizing the
softened material in a refiner to produce a wood fiber; drying and
separating the wood fiber; and screening the wood fiber to remove
unwanted fibers to provide the small animal bedding, wherein the small
animal bedding comprises a matrix of individual fibers having varying
lengths that can maintain a shape of a nest or burrow after being created
by an animal.
2. The method of claim 1, wherein the initial wood mixture comprises a mixture of hardwood species and softwood species.
3. The method of claim 1, wherein the initial wood mixture comprises only hardwood species.
4. The method of claim 1, wherein the initial wood mixture comprises only softwood species.
5. The method of claim 1, wherein preparing the initial wood mixture comprises cutting up larger portions of wood material into a smaller size for defiberization.
6. The method of claim 1, wherein filtering the initial wood mixture comprises removing wood materials from the initial wood mixture that are too large or too small to process.
7. The method of claim 1, wherein defiberization results in fiber lengths ranging from about 0.1 inches to about 2.5 inches.
8. The method of claim 1, wherein the wood fiber is dried and separated in a flash tube dryer operating at a temperature range from about 20.degree. C. to about 260.degree. C.
9. The method of claim 1, wherein the wood fiber is dried to a moisture content of about 20% or less.
10. The method of claim 1, wherein the wood fiber is dried in an oven.
11. The method of claim 1, wherein screening the wood fiber comprises feeding the wood fiber into a mechanical screening device configured to pass the wood fiber through a series of screens adapted to filter and remove large and small fibers.
12. The method of claim 1, further comprising treating the wood fiber with a surfactant.
13. The method of claim 12, wherein the surfactant makes the wood fiber hydrophobic or hydrophilic.
14. The method of claim 1, further comprising treating the wood fiber with an additive.
15. The method of claim 14, wherein the additive is a colorant applied to the wood fiber.
16. The method of claim 14, wherein the additive is a starch applied to the wood fiber configured to enhance fiber strength.
17. A fibrous material for small animal bedding, comprising one or more lignocellulosic fibers having individual fiber lengths ranging from about 0.1 inches to about 2.5 inches, and being sufficiently rigid to maintain a shape and structural integrity of a nest or burrowing area created by an animal.
18. The small animal bedding of claim 17, wherein the lignocellulosic fiber material is derived from one or more wood-based materials.
19. The small animal bedding of claim 18, wherein the wood-based material comprises a mixture of one or more hardwoods and one or more softwoods.
20. The small animal bedding of claim 17, wherein a surfactant is applied to the lignocellulosic fiber material to make the lignocellulosic fiber material hydrophobic.
CROSS-REFERENCE TO RELATED APPLICATION
 This application claims priority to U.S. Patent Application No. 61/360,865, filed on Jul. 1, 2011, the entirety of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
 1. Field of the Invention
 Embodiments provided herein generally relate to fibrous materials made of wood. More particularly, the embodiments relate to fibrous bedding made from lignocellulosic materials that are soft enough to be used for animal bedding, yet rigid enough to maintain a nesting or burrow structure.
 2. Description of the Related Art
 Small nesting and burrowing animals, such as rabbits, hamsters, guinea pigs, mice, rats, ferrets, birds, etc., are typically housed in domestic cages as pets. Animal bedding is commonly placed in the cages to provide cushion, support, and/or warmth, which are essential to the comfort and well-being of the animal. Common animal bedding, however, is generally a coarse material, such as wood shavings, corn cob pieces, cellulosic granules and/or pieces, etc. Such bedding does not permit, let alone promote, the normal nesting and burrowing instincts of these types of animals.
 What is needed, therefore, is an improved animal bedding material that not only provides a soft nesting area for the animal, but also is rigid enough to maintain a nest or burrow structure.
SUMMARY OF THE INVENTION
 Fibrous materials for small animal bedding and methods for making the same are provided. The fibrous material can include a plurality of lignocellulosic fibers of varying lengths to form a fiber matrix configured to maintain a shape and structural integrity of a nest or burrowing area created by a small animal. The method from making the fibrous material can include preparing and filtering an initial wood mixture, softening the initial wood mixture in a steam digester to produce a softened material, and defiberizing the softened material in a refiner to produce a wood fiber. The method can also include drying and separating the wood fiber, and screening the wood fiber to remove unwanted fibers to provide the fibrous material.
BRIEF DESCRIPTION OF THE DRAWINGS
 So that the recited features of the present invention can be understood in detail, a more particular description of the invention may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
 FIG. 1 depicts a schematic flowchart of a method for making fibrous material for small animal bedding, according to one or more embodiments described.
 FIG. 2 depicts an illustrative system for making the fibrous material, according to one or more embodiments described.
 FIG. 3 depicts a graphical representation of softness versus rigidity of exemplary fibrous material, according to one or more embodiments described.
 A detailed description will now be provided. Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" or "disclosure" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" or "disclosure" will refer to subject matter recited in one or more, but not necessarily all, of the claims. Each of the inventions will now be described in greater detail below, including specific embodiments, versions and examples, but the inventions are not limited to these embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the inventions, when the information in this patent is combined with available information and technology.
 FIG. 1 depicts a schematic flowchart of a method 100 for making fibrous material for small animal bedding, and FIG. 2 depicts a schematic machinery flowchart used in making the fibrous material, according to one or more embodiments described. The fibrous material can include a plurality of fibers that form a fiber matrix that is soft enough for bedding, yet sufficiently rigid to maintain the shape and structural integrity of a nest or burrowing area for small animals after the small animal has created the nest or burrowing area. In an embodiment, the fibrous material can be made from a plurality of lignocellulosic fibers, i.e. fibers that are or include both cellulose and lignin, such as wood, straw, stalks, etc.). In one embodiment, the fibrous material can be derived primarily from wood-based materials, such as from hardwoods, softwoods, or combinations thereof. Acceptable hardwoods can include, but are not limited to, aspen, maple, birch, ash, combinations thereof, and the like. Acceptable softwoods can include, but are not limited to, red pine, fir, spruce, combinations thereof, and the like. It should be noted, however, any hardwood or softwood species can be used without departing from the scope of the disclosure. Other illustrative wood-based materials can include paper, cardboard, wood mulch, and the like.
 The wood-based material can be provided in a wide range of sizes and mediums. For example, in one or more embodiments, the wood-based material can include wood chips, shavings, boards, logs, panels, sawdust, or lumber rejects obtained as a by-product from a lumberyard or similar facility. The wood-based material can also be obtained from construction waste, such as scrap wood from residential home construction or scrap, waste, and trimmings from wood-working industrial facilities and yards. As can be appreciated, the wood-based materials can be obtained from other sources not specifically disclosed herein, without departing from the scope of the disclosure.
 In one or more embodiments, the wood-based material can be a mixture of one or more types of hardwoods and/or one or more types of softwoods, thereby providing an initial wood mixture. Some initial wood mixtures can have more hardwood than softwood, and vice versa. Other initial wood mixtures can have equal amounts of both. In other embodiments, the initial wood mixture can be or include all hardwood or all softwood. For example, suitable initial wood mixtures can contain one or more hardwoods in an amount ranging from a low of about 1 wt %, 5 wt %, or 10 wt % to a high of about 60 wt %, 75 wt %, or 90 wt %, based on the total weight of the wood mixture. The amount of hardwood can also range from about 5 wt % to about 90 wt %; or about 10 wt % to about 80 wt %; or about 25 wt % to about 65 wt %, based on the total weight of the wood mixture. Other illustrative wood mixtures can contain one or more softwoods in an amount ranging from a low of about 1 wt %, 5 wt %, or 10 wt % to a high of about 60 wt %, 75 wt %, or 90 wt %, based on the total weight of the initial wood mixture. The amount of softwood can also range from about 5 wt % to about 90 wt %; or about 10 wt % to about 80 wt %; or about 25 wt % to about 65 wt %, based on the total weight of the initial wood mixture.
 Referring to FIGS. 1 and 2, the initial wood mixture can be prepared and filtered for processing, as at 102. Because larger pieces of wood do not soften very well, the initial wood mixture can be prepared for processing by mechanically grinding or cutting up larger chunks or pieces of wood into smaller or more manageable sizes suitable for introduction into downstream machinery. For example, some of the wood-based materials can be large pieces of wood, such as boards, logs, panels, etc., that are too large to process since they will not fit into downstream machinery and therefore require size reduction before defiberization can be undertaken. Larger chunks of wood can tend to bunch up in machinery pipes airlocks or get caught on screws as they are moved through the process. Large pieces of wood can be reduced in size using one or more preparation stage machines 202 (FIG. 2) such as any one or more, chippers, shredders, grinders, hogging machines, or the like, thereby resulting in wood chips that can be easily placed into downstream machinery. In one or more embodiments, the length and width of a suitable wood chip can range from a low of about 0.1 in., about 0.5 in., or about 1 in., to a high of about 1.5 in., about 2 in., or about 2.5 in. The thickness of a suitable wood chip can range from a low of about 0.0625 in., about 0.1 in., or about 0.125 in., to a high of about 0.2 in., or about 0.25 in. As can be appreciated, however, varying sizes of wood chips can be used depending on the capabilities of the machinery and/or process.
 To filter the initial wood mixture, the initial wood mixture can be processed through one or more filtration machines 204 (FIG. 2), such as one or more shakers, sifters, and/or screens, adapted to remove or otherwise separate wood chips and other materials that are too large to effectively process. The rejected materials can be returned to the preparation stage machines 202 to be mechanically reduced in size, as described above, and then re-introduced into the filtration machines 204 for processing. For example, chip sizes measuring generally over about 2.5 in. length can be removed for re-processing.
 In one or more embodiments, the filtration can also be adapted to remove wood fines (e.g., fine sawdust and the like) from the initial wood mixture that are too small to process. As can be appreciated, wood fines may produce fiber lengths that are too small and therefore not amenable to making suitable fibrous bedding material. For example, the small fibers produced from wood fines may not be large enough to form fibrous matrices with other fibers and would not be able to maintain the shape or rigidity of a nest or burrow created by an animal. Moreover, small fibers produced from wood fines can potentially be inhaled by the animal and cause pulmonary problems. As can be appreciated, however, other embodiments can leave the wood fines in the mixture for processing and generation of the fibrous material, without departing from the scope of the disclosure. In at least one embodiment, however, fines to be removed can be any material that falls through a diamond roll filtration screen having gap of about roughly 0.0625 in.
 The filtered material can then be conveyed to one or more wood softening devices 206 (FIG. 2), such as a steam digester or the like, to undergo a softening process, as at 104. In at least one embodiment, the steam digester can be pressurized to operate at pressures ranging from about 100 psi to about 150 psi, from about 110 psi to about 140 psi, from about 120 psi to about 130 psi, or from about 125 psi to about 130 psi. In operation, the steam digester 206 can be configured to soften the filtered material so that the fibrous content of the wood can be subsequently torn apart and separated into individual fiber lengths. In an embodiment, the moisture content of the softened material can range from a low of about 30% or more, about 35% or more, about 40% or more or about 50% or more, to a high of about 55% or more, about 60% or more, about 65% or more, or about 70% or more. As used herein, the term "moisture content" refers to the amount of water in the fibrous material, based on total weight percent of the fiber and water.
 The softened material can then undergo defiberization to produce wood fibers, as at 106. Defiberization can also be undertaken using a dry material, without departing from the scope of the disclosure. The defiberization process can be undertaken using one or more pressurized refiners 208 (FIG. 2), such as a model 418 double disk refiner, available through Bauer Bros. Co. As can be appreciated by those skilled in the art, defiberization can result in the production of either coarse or fine wood fibers, depending on the specific refiner used. In an illustrative double disk refiner, the disks are opposing refiner plates having lateral protrusions that are used to break down clumps of fibers into individual fiber lengths. In one embodiment, the refiner plates can be Andritz Sprout-Bauer plates having a #36314 face pattern, however, other manufacturers and face patterns can also be employed to achieve the same end. In operation, a first refiner plate is mounted on a rotor for rotation while the other refiner plate can either be mounted on an adjacent stationary surface or moveable such that both plates move relative to one another. As the softened material passes between the opposing refiner plates, relative rotation between the opposing plates can serve to tear and/or separate the material into individual fiber lengths.
 The wood fibers from the defiberization process can be conveyed to one or more dryers 210 (FIG. 2) to dry and separate the fibers into respective individual fiber lengths, as at 108. In an embodiment, the separated individual fiber lengths can generally match the length of the original wood chip size. For example, the resulting fibers can include lengths ranging from a low of about 0.1 in., about 0.5 in., or about 1 in., to a high of about 1.5 in., about 2 in., or about 2.5 in. In an embodiment, the fibrous material can be dried to a moisture content of about 70% or less, about 60% or less, about 50% or less, about 40% or less, about 30% or less, about 20% or less, or about 10% or less.
 In one or more embodiments, the coarse or fine wood fibers can be dried in a flash tube dryer that uses hot air to pneumatically convey and dry the wood fibers simultaneously by generating a high-efficiency cyclone near its outlet. The cyclone generated within the flash tube dryer can serve to separate the fibrous material into individual fibers. As can be appreciated, the temperature and time duration in the flash tube dryer can vary depending on the desired moisture content of the fibrous material. For example, the flash tube dryer can be maintained at temperatures ranging from a low of about 20° C., 30° C., or 40° C., to a high of about 240° C., 250° C., or 260° C., and the fibers can be blown within the flash tube dryer for a time ranging from a low of about 2 seconds, 5 seconds, 10 seconds, or 1 minute, to a high of about 10 minutes, 30 minutes, or 1 hour or more. In at least one specific embodiment, the wood fibers can be blown through the flash tube dryer for about 2 seconds to about 5 seconds at inlet temperatures ranging from about 175° C. to about 205° C. or more and outlet temperatures of about 65° C. to about 95° C. or more, to obtain a moisture content of about 15% to about 20%.
 In other embodiments, the wood fibers can be dried by spreading the fibers on a series drying mats or conveyors, and subsequently subjecting the mats/conveyors to increased temperatures in a kiln, oven, or the like. While in the kiln/oven, the wood fiber can be heated to temperatures ranging from about 50° C. or more, about 100° C. or more, about 150° C. or more, about 200° C. or more, or about 250° C. or more. The wood fibers can remain in the kiln/oven for a predetermined time ranging from a low of about 5 minutes, 10 minutes, 20 minutes, or 30 minutes, to high of about 1 hour, about 2 hours, or about 3 hours. In one or more embodiments, the fibrous material can be heated for a period of minutes, hours, or days. The resulting moisture content of the fiber can be manipulated by adjusting both the time and temperature in the kiln/oven. Subsequently, the individual fibers can be separated in this embodiment by mechanically shaking and/or pulsating the dried fibrous material.
 In addition to removing moisture from the fibrous material, heating the material can also serve to sterilize it. The heat applied to the fibrous material can kill or otherwise neutralize bacteria, fungus, viruses, microbes, or the like that may be on, in, or about the material. Furthermore, heating the fibrous material can also reduce harmful, naturally-occurring aromaticity common in cedar products, and also neutralize abeitic acids in pines which has been shown to be an allergen to animals.
 The dried and separated fibers can be screened to remove unwanted fibers, as at 110. Following separation, appropriately-sized fibers can be packaged for storage, shipping, or sale to consumers. In one or more embodiments, the dried fibers can be fed into one or more mechanical screening devices 212 (FIG. 2), or similar mechanisms, configured to pass the dried fibers over a series of screens disposed at varying levels adapted to filter or otherwise remove fibers that are too large and fibers that are too small for small animal bedding. Larger fibers may not be amenable to forming adequate fiber matrices required to create small animal nests or burrows, or they may be prove excessively bulky for the comfort of the animal. Furthermore, as explained above, aspiration of small fibers can be detrimental to the pulmonary health of small animals. Therefore, removal of such small and large fibers can prove advantageous.
 As can be appreciated, the process of removing unwanted or unusable fibers can be undertaken via a variety of screening devices 212 and/or methods, and should not be considered limited to those disclosed herein. For example, fiber screening can also be undertaken using pneumatic or centrifugal separators to achieve the same end.
 In one embodiment, the larger separated fibers can be optionally recycled back into the beginning of the process cycle to undergo re-processing and/or size reduction, as at 111. In other embodiments, the larger and smaller separated fibers can be used in other applications or products. For example, rejected fibers can be used as fuel for boilers or other similar devices. Moreover, rejected fibers can be used in products such as, but not limited to, plaster, tile adhesives, grouting for gypsum plasterboard, glue, reinforcing compounds for thermal insulation systems, joint and other fillers, emulsion paints, abrasives, meat smoking agents, structure reinforcers and fillers, paper, paperboard, fiberboard, plastics, such as thermoplastics and duroplastics, detergents, and brake pads, or the like.
 In one or more embodiments, an additive and/or surfactant can be added to the fibrous material, as at 112. For example, the fibrous material can be treated with an appropriate additive or surfactant to modify properties of the fibers such as, but not limited to, color, strength, hydrophilicity, hydrophobicity, odor masking/absorbing characteristics, or combinations thereof In some embodiments, the surfactant can be non-ionic, cationic, anionic, or amphoteric. In one or more embodiments, the surfactant can be substantially free of polyoxyethylene groups. In one or more embodiments, the surfactant can be or include halogen-capped (e.g., chlorine capped) surfactants, linear alcohol based surfactants, or alkoxylated (e.g., ethoxylated or propoxylated) alcohol surfactants. In at least one specific embodiment, the surfactant can be or include branched alcohol ethyoxylates, for example decyl alcohol ethoxylates having a Hydrophile/Lipophile Balance ("HLB") value ranging from a low of about 7, about 9, or about 11 to a high of about 13, about 14, or about 15. Illustrative and commercially available surfactants can include, but are not limited to the RhodaSurf® DA series of non-ionic surfactants available from Rhodia, which are described as branched isodecyl alcohol ethoxylates. For example, the surfactant can be or include RhodaSurf DA-639, which is a 90% solution of RhodaSurf DA-630, which has been described as having 6 moles of ethoxylation and an HLB of 12.5. Other illustrative and commercially available surfactants can include, but are not limited to, Surfonic® surfactants available from Huntsman, Marlipal® and Alonic surfactants available from Sasol, Desonic surfactants available from Crompton, Trycol® surfactants available from Cognis, Iconol surfactants available from BASF, and Genapol® surfactants available from Clariant.
 Illustrative additives can include, but are not limited to, defoamers, antifoamers, dispersants, lubricants, crosslinkers, antislipping agents, waxes, wax emulsions, resins, thickeners, fire retardants, and insolubilizers. Other illustrative additives can include colorants configured to alter the color of the fibrous material, or starches to enhance the stability of the burrow or nest of a small animal. As can be appreciated, the fibrous material can be treated with any number of additives or surfactants, and should not be limited to those specifically disclosed herein.
 The addition or application of additives/surfactants to the fibrous material can be undertaken at various points throughout the methods disclosed herein. For example, treatment with additives/surfactants can be done before drying and separating the wood fibers. Alternatively, this can be done after drying and separation, but before screening the dried and separated fibers. This can also be done after screening the fibrous material, but before packaging for transport or sale.
 Referring to FIG. 3, depicted is a graphical representation that generally quantifies acceptable fibrous material, according to at least one embodiment. As indicated previously, the resulting fibrous material can be soft enough for bedding, yet sufficiently rigid to maintain the shape and structural integrity of a nest or burrowing area for small animals after the small animal has created the nest or burrowing area. According to FIG. 3, the fibers testing within the area indicated by 302 can exhibit the ideal combination of softness and rigidity. As can readily be seen, fibrous material that is more soft than rigid, more long than short, and more thin than thick is generally favored. However, such characteristics can be altered or adjusted to suit varying applications including preferences of varying animals, without departing from the scope of the disclosure.
 Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges from any lower limit to any upper limit are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are "about" or "approximately" the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.
 Various terms have been defined above. To the extent a term used in a claim is not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure is not inconsistent with this application and for all jurisdictions in which such incorporation is permitted.
 While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
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