Animal husbandry – Material for absorbing moisture from waste product
Reexamination Certificate
1999-09-29
2001-04-24
Price, Thomas (Department: 3643)
Animal husbandry
Material for absorbing moisture from waste product
Reexamination Certificate
active
06220206
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a biodegradable, nondusting cat litter and a method of making such cat litter. In particular, the present invention relates to a cat litter made from at least one starch-containing byproduct of a grain milling process.
DESCRIPTION OF THE PRIOR ART
It is well known that materials known as cat litter are used as a sorbent for household pet waste, both solid and liquid. Traditionally, cat litter has been made from clay, because clay absorbs some moisture, is inexpensive, and can be easily disposed of in a trash can. Clay also clumps when wet, which makes it easier for a pet owner to selectively remove the used cat litter from the litter box. The clay clumps, however, have a relatively low cohesiveness, resulting in a tendency to crumble after drying, and to break up when removed from the litter box, thereby defeating the purpose of clumping. This is problematic because disposal of the waste is made difficult, and the likelihood of waste products remaining in the litter box is increased. This in turn increases the likelihood of foul odors emanating from the litter box as a result of the remaining waste.
Dusting is an additional problem associated with clay-based cat litters as the clay based litter typically has an amount of dust that the cat often tracks throughout a household. It is known that cat owners most frequently complain about dusting problems. Dust is created during the production process as a result of drying the clay particles and then milling the particles. The milling process causes the formation of fines or small particles, which become an integral part of the litter matrix. As such, the dust typically collects in the packaging containing the litter. This dust is then released when the package is opened by a consumer. Once the litter is poured into a litter box, further dust dissipation typically occurs when the cat walks through the litter, as a majority of the dust particles will have collected in the litter box, and as such are available for dispersion into the air. There is also a tendency for the dust to stick to the cat's fur, which can cause the soiling of furniture contacted by the cat. Further, dusting can be dangerous to the cat, as the cat can contract tuberculosis from breathing the dust. Therefore, clay litters are untidy, potentially unhealthy, and unsanitary.
Another problem associated with clay litter is that it has comparatively poor absorption capacity. This in turn allows the animal urine to pool and collect on the bottom of the litter box, which then releases ammonia. Other undesired odors result because of bacteria growth in the pooled urine.
Clay litters are also not readily biodegradable, and therefore cannot be disposed of through a sewer or septic system because the litter will typically clog the system. In turn, because clay litters are not readily biodegradable, the litter must be disposed of in a landfill, which raises environmental concerns.
In an attempt to overcome some of the problems associated with clay-based litters, alternative cat litters have been developed that are made from fibrous or cellulosic materials such as wastepaper, sawdust, or plant hulls. These materials are biodegradable and therefore provide a cat litter which is more conducive to being disposed of through a sewer or septic system; however, because cellulosic materials characteristically swell to excess when wetted, they still are likely to cause blockage of a sewer or septic system if disposed of in this manner. This again means that the litter will most likely be disposed of in a landfill. As such, an environmentally friendly cat litter is desired.
Fibrous litters also have some of the same problems as clay litters, such as dusting, poor absorption capacity, and the absence of an ability to naturally neutralize urine or eliminate odors associated with animal urine. These types of cat litter have dusting problems because the cellulosic or fibrous materials generally are not tightly bound when formed into the litter particles; as a result, the litter particles are easily broken when the cat walks through the litter. The fibrous litter particles typically have a low density, meaning the particles could become airborne and readily disperse when broken. There is also a tendency for the litter to stick to the paws or fur of the animal, which means that, like the clay based litters, tracking will be a problem. Further, many fibrous and cellulosic materials have an associated natural odor which is considered unpleasant by many consumers.
In an attempt to alleviate the dusting problem associated with cat litters, wetting additives such as surfactants and other binders have been added to cat litter products in order to bind dust and fines contained in the litter. The problem with additives, such as surfactants, is that they make the process for making the cat litter more complicated and more expensive.
In an effort to eliminate odor problems, animal litters have been developed which are made from ground alfalfa (which is a fibrous constituent). It is known that chlorophyll, indigenous to the alfalfa, will control odors. Alfalfa is known, however, to have its own profound, unpleasant odor, particularly when wet, which is believed to be undesired by consumers. In an effort to reduce the natural odor of alfalfa in cat litter products, the process of making the litter may include cooking or otherwise dehydrating the alfalfa prior to mixing with the other litter components, or aerating the particles after they have been dried. This adds to the expense and complexity of the process, and does not remove all of the odor associated with alfalfa. Further, alfalfa does not contain a natural buffering agent found in other natural grain products, such as wheat, which helps to maintain the pH of the litter once it has been wetted by the animal. The pH of the urine is not adequately neutralized by alfalfa mixtures, resulting in insufficient odor control; specifically, the effects of ammonia are not neutralized. In addition, unless a coating, such as a surfactant, is added it is believed that animal litter made from alfalfa will have dusting problems. Also, the greenish tint of the alfalfabased litter is believed to be undesirable to consumers.
The use of starch as a constituent in animal litters has been taught. Some patents, such as Fry et al., U.S. Pat. No. 3,923,005 ('005); House, U.S. Pat. No. 5,230,305 ('305); and Ducharme, et al., U.S. Pat. No. 4,727,824 ('824), have disclosed litters bound in part by starches and starch-containing materials. The '005 patent discloses mixing dried, finely-ground alfalfa with a starch-containing material, preferably wheat middling, to produce an animal litter. However, as discussed above, the use of alfalfa in animal litters presents several problems. Also, it is known that wheat middling is comprised of bran and minimal amounts of starch. Since there is a comparatively small amount of starch, it is hypothesized that the cat litter particles of the '005 patent will be insufficiently bound because not enough binding agent is present. Further, alfalfa is believed to not be very absorbent, and that the bran in the wheat middling will only absorb a small amount of moisture. Thus, the litter may not provide sufficient moisture absorption and most likely will be dusting.
The '305 patent also discloses a scoopable cat litter which uses starch-containing natural products; however, the starch is modified by incorporating liquefied gas into the tissue structure of the raw starch material until it obtains a bulk density ranging between about 500 kg/m
3
and about
900
kg/m
3
. The density of the resulting litter is believed to be too high and the process appears to be comparatively expensive.
The '824 patent discloses the use of flour or starch as a binder for an animal litter composition. However, the litter composition is comprised of only about 2% to about 25% binder by weight. It is believed that this relatively small amount of starch component will be inadequat
Moore Wayne R.
Sotillo Vidal E.
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