CA1160442A - Animal litter and method of preparation - Google Patents

Abstract

ANIMAL LITTER AND METHOD OF PREPARATION

ABSTRACT OF THE DISCLOSURE

The animal litter comprises a litter of paper mate-rial that contains a pheromone-like attractant substance which makes the litter attractive to animals seeking a place to defecate and/or urinate. The litter material is pelletized to give the litter a consistency comparable to that of fine gravel. The pellets formed from the litter material hydrate slowly but positively and are disposable in water. The density of the pellets is such that they retain their structural integrity on hydration. The pellets are formed from ground paper having a low clay and mineral content which has been moistened with sufficient water to hold the particles together but not so much as to cause the pellets to feel moist. An acid salt may either be added in the water or as a dry powder to the ground pa-per. This salt carried by the water in the pellets neu-tralizes the animal urine (and the ammonia-like compounds formed from it) while maintaining the pH of the litter at a level acceptable to the animals. A pheromone-like attrac-tant substance is added to the pellets either with the water or by spraying it on the finished pellets. A further step comprises compacting the saturated, ground paper into pel-lets having the previously enumerated properties.

Description

ANIMAL LITTER AND METHOD OF PREPARATION

The present invention relates to an animal litter and method of preparation of animal litter, and pertains more particularly to an animal litter with chemical addi-tives and physical properties which increase the attrac-tiveness of the litter to the animal. -Prior to the development of the present animallitter, principally three types of litter material were known: clay and expanded clay; alfalfa or grass pellets;
and wood chips or sawdust. Each of these types of materials has serious disadvantages when used as a litter base. Clay, because of its high density, is difficult to carry in quantities sufficient for an extended period of use. Even more serious is the disposal problem asso-ciated with clay. Clay cannot be disposed of directly on a lawn, nor can it be emptied into the garbage or in the garden. Also, i-t is difficult and undesirable to dispose of a clay-containing product through an ordinary flush-type toilet. U. S. Patent No. 4,007,708 discloses one such clay type litter. Another cIay-type or relatively high ~0 mineral filler litter is described in U. S. Patent No.
4,203,~88. This patent refers to the making of recycled paper, the longer fibers in the recycling process being drawn off to produce the recycled paper and the shorter fi~ers, accompanied by the mineral filler, forming what are termed rejects which are concentrated in a sedimenta-tion tank.
Alfalfa or grass pellets also have serious defi-ciencies. Because -these types of li-tter are edi~l~ by bacteria, they tend to mold and develop unpleasan-t odors.

~--` 11 6(~2 Paper, on the other hand, is not as likely to be subject to bacterial growth. U. S. Patent No. 3,789,797 dis-closes a cat litter product prepared with an alfalfa base.
A third kind of litter is made from sawdust, wood chips or bark and fiber crumbs. These litter materials are not effective because they have a wood odor that is unpleasant to the animal. In addition, these pellets are not as absorbent as paper. Cellulose will absorb more water because it does not have lignin and wood tars and turpentines. U. S. Patent No. 3,980,050 describes one such litter made from bark and fiber crumbs.
U. S. Patent No. 3,828,731 discloses an animal litter product consisting of soft and fluffy paper shav-ings. The problem with the use of paper shavings is that they stick to the feel of the animal after use. With use, the litter is spread outside of the litter tray and is disliked by the animal because the paper shavings adhere to its feet. Also, when this happensi khe resulting tracking becomes objectionable.
In addition to the deficiencies of the known animal litters as enumerated above, there are other im-portant problems associated with their use. The most important of these is related to the effectiveness of `
the prior art litters. A common problem associated with ~5 the use of an animal litter is that of training the animal to use the litter with a high level of consistency.
None of the prior art litters incorporates any features which would make the litter particularly attractive to the animal. While many of these litters contain an odor-inhibiting or masking substance to mask or prevent the formation of odors undesirable to humans, none of the litter products~contains a substance that makes the lit-ter attractive to animals. In addition, the physical characteristics of the prior art litters has been predi-cated by the availability of litter materials. As a result, the characteristics of some of these litter materials such as paper shavings, is particularly un-attractive to the animal. None of khe prior art litters .

0~42 is prepared to duplicate the consistency of natural soil, which is a mixture of silica and carbonaceous matter. Such a soil-like material is the most attractive type of mate-rial for an animal seeking a place to defecate and/ox urinate.
Of the listed prior art the use of pelletized recycled paper is disclosed in U. S. Patent 4,203,388, but is accompanied by a high percentage of mineral fil-ler, chiefly clay. U. S. Patent 3,921,581 discloses the pelletizing of particles, but applies it only to the solid excipients which are used as additives to the cat litter rather than the cat litter product itself. U. S.
Patent 3,789,797 discloses pelletizing the cat litter product, but in a form which involves merely tumbling the mixture together so that it adheres in a snowball form in a noncompacted state. As will be discussed later, there are a number of advantages associated with the use of paper pellets as the litter material.
The animal litter comprises a moisture-absorbent litter material that contains a pheromone-like attractant substance which makes the litter attractive to animals seeking a place to defecate and/or urinate. The litter material is pelletized to give the litter a consistency comparabie to that of moist soil. The pellets have a density sufficient to ensure their structural integrity on hydration, yet low enough that hydration readily occurs.
The pelletized litter material is disposable in water.
The water content of the litter, 10-25% by dry weight, gives the litter a water content comparable to that of moist soil. Normally, the litter material contains an acid salt that neutralizes animal urine while maintaining the pH of the litter at a level acceptable to animals.
In its specific preferred form, the animal litter is made of ground paper pellets that have a density of ap-proximately one cubic centimeter per gram. The pheromone-like attractant substance in the litter is 100-5,000 ppm by weight of the litter. The particular acid salt em-ployed in the litter is sodium acid sulfate. It is used --" l 1604~2 in a quantity sufficient to maintain the pH of the litter between 4 and 4.5.
The initial step in preparing the animal litter comprises adding the pheromone-like attractant substance to water although such pheromone can be added at the end of the preparation process by spraying the same on the finished pellets. The acid salt may be added to the re-sulting aqueous solution either before or after the addi-tion of the pheromone-like substance. Alternatively, the acid salt may be added in powder form directly to ground paper. The paper should have as low a clay and mineral content as practical. The aqueous solution containing the pheromone-like substance (and, alternatively, the acid salt) is then mixed with the ground paper in quantities such that the paper has a water content of 10-25% (by dry weight) of the litter, which is comparable to that of moist soil. The method of preparation of the animal lit-ter may further comprise the compacting of the ground paper into pellets after the resulting aqueous solution has been absorbed. The litter material is pelletized so that the consistency of the litter is comparable to that of slightly moist soil. The final product should be as free of clay and mineral content as possible, preferably having a combined content of less than 0.5% on a dry weight basis.
The present invention minimizes or eliminates those problems that existed in the prior art. One of the most important advantages associated with the use of cellulose as the litter material is that it is biodegradable and easily disposable. When containing little or no clay or other mineral filler, paper pellets may be easily flushed down the toilet, or disposed of in the garden. Another advantage associated with the use of cellulose in the form of paper is the existence of naturally occurring buffers in the paper cellulose. These naturally occurring buffers enhance the effect of the acid salts that are added to the litter material. Paper is also a particularly attractive litter material because it is very absorbent, and it is not as susceptible to microorganisms as materials such as hay or alfalfa.

~ 1 60~2 -Another of the important advantages associated with the use of the present animal litter i5 its deg~ee of effectiveness as a litter. As already indicated, one of the major drawbacks of the prior art litters was their marginal level of effectiveness. In contrast, the present animal litter is highly effective for several reasons:
First, because of the pheromone-like attractant substance added to the litter, the animaI is naturally attracted to the litter when seeking a place to deposit its urine or feces. While other litters use an odor-inhibiting or masking substance to mask or prevent the formation of un-desirable odors, none of the prior art litters 1ncorporates a substance that actually attracts the animal to the litter.
Second, the physical and chemical properties of the present animal litter are unlike those of any of the prior art litters. By adding water to the litter material and pelletizing the litter material, the litter approximates the texture and consistency of moist soil or preferably fine gravel. Animals that naturally use the soil to void themselves find -the present litter material an acceptable substitute. In contrast, the prior art litter materials either stick to -the feet of the animal, or exude~
odors that are unpleasant to the animal. Thus, pelletizing the litter material not only eliminates the disposal problems, but also enhances the attractiveness of the litter to the animal. Thirdly, the odor is neutralized with a material such as an acid salt. Fourthly, being virtually devoid of any clay or minerals, it is disposable by flushing down a toilet. Fifthly, it does no-t have a dusty nature when dry or a muddy nature when wet.
In the drawing which forms a part of this application, the single figure is ~ flow diagram of the method by which the animal litter is prepared.
The animal litter comprises paper pellets.
Currently, the pellets are made from hot melt paper, which is the trimming from books and magazines. Virtually any kind of paper having a low clay content may be used to form the pellets. Actually, the less clay or mineral " ~ 1 60~

content, the better. Hot melt scrap paper is used be-cause of its availability, low cost, and low mineral content.
The pellets typically have a density of one cubic centimeter per gram. A density in the range of 0.75 cu-bic centimeter per gram to 1.1 cubic centimeters per gram is preferred: if the pellets have a density beneath this range, they are too fragile and will tend to break apart and adhere to the feet of the animal; if the density of the pellets is above the preferred density range, the pellets become glassy, almost like coal, and will not readily absorb water. The above-alluded to density range reflects the small amount of mineral fillerj clay in particular, included in the pellets which mineral content should preferably not be over 0.5% (by dry weight).
The preferred size of the pellets is approximately 0.4 centimeter in diameter by 1.25 centimeters in length, although diameters of approximately 0.16 to 0.80 centi-meter and lengths of slightly more than 0.5 centimeter are acceptable. A typicaI bulk density for the animal litter is 2.4 cubic centimeters per gram. The 0.4 x 1.25 centimeter size was chosen because it gives the litter a texture similar to that of slightly moist soil and keeps the dust generated by the pellets to a minimum. In addition, pellets of this size can be readily disposed of in the sewer system.
Preferably, the pellets have a moisture content of 13 to 19~ (by dry weight) of the litter; however, a moisture content in the range of 10-25% is acceptable. The moist-ure in the pellets is essential to give the pellets theirstructural integrity. A moisture level under 10% would make it difficult to pelletize the litter material.
Also, a low moisture content tends to make the pellets somewhat dusty. On the other hand, a moisture content that is too high may create spoilage problems, although pellets of paper are not as susceptible to spoilage as is hay.
In addition to facilitating the pelletizing of the litter material, the moisture in the pellets makes the litter more attractive to the animal using the litter. A moisture ~ 1 1 80~4~

content in the preferred range gives the litter the characteristics of moist soil.
The litter also contains a chemical substance that imparts an odor to the litter that is attractive to animals seeking a place to defecate and/or urinate. In this respect, the present animal litter differs fundamentally from prior art litters in which the litter odor was selected to be attractive to the animal owner. The odor used has a smell apparently similar to that of an animal pheromone. Phero-mones are chemicals which are secreted or excreted by oneanimal that affect the behavior of other animals of the same species. For example, a dog has in its urine pheromones that enable it to stake out its territory. The male moth is attracted to the female moth because of her sex-attractant pheromones. The chemical used in the presentanimal litter has a musty, damp, sour-like odor similar to that of mushrooms. The chemical is available from Polok Fructal Works, Middletown, New York, a division of Hercules.
The principal distinction between the pheromone-like attractant substance and other odor additives is that the primary purpose of the pheromone-like substance is not to mask the odor of the litter, but rather to attract the animal to the litter. The preferred concentration of the pheromone-like attractant substance is approximately one part per thousand by weight, although a concentration in the range of 100-5,000 ppm by weight is acceptable.
Another important component of the animal litter is the acid salt, which neutralizes the urine (and ammonia type compounds derived from urine) of the animal and buf-fers the litter. By neutralizing the urine, the acid saltprevents the formation and release of ammonia odors result-ing from the urine. The preferred acid salt for the animal litter is sodium acid sulfate. That particular acid salt was chosen because it is inexpensive and readily available.
Alternatively, nitric, phosphoric or hydrochloric acid salts, among others, could be used. In addition, a borax, boric acid mixture would be effective because it is both acidic ---` ` 11 60~42 and a deodorant. All of these mixtures are capable of preventing ammonia formation and bufering the litter to control the pH.
The pre~erred pH of the litter is in the range of 4 to 4.5, which is the acid strength of sour milk. A pH
level in the range of 4 to 4.5 ensures that the litter is not too acidic for the animal, although a pH range from 1 to 5.5 is acceptable. Over the preferred range, the sodium acid sulfate is used in a concentration of 1-2~.
If more than 2~ sodium acid sulfate is used, the pH drops below 4. If the sodium acid sulfate concentration is below 1~, the pH rises considerably over 4.
While the most important contribution to the buf-ering effect is from the added acid salt, the cellulose itself acts as a buffer as a result of the naturally occur-ring sulfates and other chemicals in the cellulose.
The pre~erred method of preparation of the animal litter is as follows. First, reasonably clean baled paper having a low clay and mineral content, such as hot melt scrap paper, is run through an a~itator to evenly disperse the paper. From the agitator it enters a hammer mill with approximately 1/4 inch holes. Newspaper or cardboard boxes also could be used. The ground paper is then blown into a dust collector. The dust collector allows the paper to set-tle in a paper hopper. From the bottom of the hoppèr thepaper is conveyed by a discharge screw to a pelletizer.
Dry sodium acid sulfate is added to the paper as it is dis-charged from the hopper.
The pelletizer used is a California Pellet Mill.
The pellets could be formed or compacted in a pharmaceuti-cal tablet press, an extruder or some variation o~ an extruder. In the pelletizer, the ground paper enters a mixing chamber where i~ is mixed with an aqueous solution containing the pheromone-like substance. Alternatively, pheromone could be added at the end by spraying on the pel-lets~ Also, the sodium acid sulfate could be added to the mixing chamber either in a separate stream or in the same stream as the aqueous solution. From the mixing ahamber, 1 60~2 the wetted ground paper is trans~erred to a hopper and then is conveyed into the pellet drum of the pellet mill.
The pellets formed drop onto a conveyor belt that carries the pellets to a bucket elevator, which in turn carries the paper over a 1/4 inch screen. The fines from the paper drop back to the mixing chamber while the pellets are carried into a volumetric delivering device for bagging.
The details of the step in which the litter mate-rial is compacted into pellets are of importance. If the cellulose is pelletized too lightly, the resulting pellets tend to fall apart. On the other hand, if the cellulose litter material is pelletized until it is glassy, almost like coal, it will not absorb any water. It is therefore imperative that the litter material be pelletized until is is firm enough to stay together and yet not so tight that it will not absorb water. The proper density and size of the pellets are controlled by the size of the pellet mill hole, the taper of the hole, the moisture content of the pellets and the temperature at which the pellet machine is operated. These parameters vary with the paper stock that is selected and also to some extent with respect to the particular pellet mill that is used. The contribution of various parameters, however, is apparent: as moisture is added, the pellets become more dense; as the holes are made smaller, the pellets become more dense; as the hole through which the pellets are driven is lengthened, the pellets become more compact. Each of these parameters may be varied until the optimum pellet density is achieved. As previous-ly indicated, a density of one cubic centimeter per gram prod~ces pellets with the best combination of physical characteristics. However, as already mentioned, a density range of 0.75 cubic centimeter per gram to 1.1 cubic centi-meters per gram is acceptable. By producing pellets having a combined clay and mineral content of 0.5% or less, the preferred density range can be readily realized in practice.

Claims (13)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An animal litter comprising a moisture absorbent paper material that is pelletized so that a. the consistency of the litter is comparable to that of slightly moist soil b. the pellets hydrate readily and are disposable in water; and c. the pellets have a density in the range of 0.75 cubic centimeters per gram to 1.1 cubic centimeter per gram and are sufficiently dense that they retain their structural integrity on hydration.

2. An animal litter in accordance with Claim l in which said pellets have a density of approximately 1.0 cubic centimeter per gram.

3. An animal litter in accordance with Claim 1 in which said pellets have a combined clay and mineral content of not more than 0.5% by dry weight of the litter. ~ ~

4. An animal litter in accordance with Claim l in which said pellets have a thickness of from 0.16 -0.80 centimeter.

5. The animal litter in accordance with Claim 1 in which the cross section of said pellets is generally circular and the diameter thereof is said 0.16 - 0.80 centimeter.

6. The animal litter in accordance with Claim 5 in which said pellets have a length of approximately lo 25 centimeters.

7. The animal litter in accordance with Claim 1 in which said moisture content is 13 - 19% by dry weight of the litter.

8. An animal litter in accordance with Claim 1 wherein the pellets contain an acid salt that neutralizes animal urine while maintaining the pH of the litter at a level acceptable to animals.

9. An animal litter in accordance with Claim 8 wherein the pellets contain an acid salt which maintains the pH of the litter between 4 and 4.5.

10. An animal litter in accordance with Claim 1 in which said pellets contain a pheromone-like attractant substance.

11. An animal litter in accordance with Claim 10 where the pheromone-like attractant substance is 100 - 5,000 parts per million of the litter.

12. An animal litter in accordance with Claim 1 in which said paper material is ground paper.

13. An animal litter comprising a moisture-absorbent litter material of pelletized scrap hot melt paper that contains a pheromone-like attractant substance which makes the litter attractive to animals seeking a place to defecate and/or urinate wherein the water content of the litter if 10 - 25% by dry weight of the litter, the water content and consistency of the litter being comparable to that of slightly moist soil and in which the pellets hydrate readily and are disposable in water and in which the pellets are sufficiently dense that they retain their structural integrity on hydration, the pellets have a density of approximately one cubic centimeter per gram, wherein the pheromone-like attractant substance is 100 - 5,000 parts per million by weight of the litter, and the litter material contains sodium acid sulfate to neutralize animal urine while maintaining the pH of the litter between 4 and 4.5.