WO1991005464A1

WO1991005464A1 - An animal litter containing zeolite

Info

Publication number: WO1991005464A1
Application number: PCT/US1990/005891
Authority: WO
Inventors: Thomas E. Nelson
Original assignee: Nelson Thomas E
Priority date: 1989-10-13
Filing date: 1990-10-15
Publication date: 1991-05-02
Also published as: AU6756390A

Abstract

An animal litter is disclosed comprised of a heat treated clay and a zeolite. An animal litter is also disclosed comprised solely of zeolite.

Description

AN ANIMAL LITTER CONTAINING ZEOLITE

TECHNICAL FIELD

The present invention relates to the field of animal litters and, more particularly to animal litters containing zeolites. Still more particularly, the present invention relates to an animal litter containing zeolites, alone or in combination with a clay material. BACKGROUND OF THE INVENTION

Certain forms of zeolitic substances have been used in the past in animal litters, alone or in combination with other substances, to entrap ammonia which is a major source of odor in used litter. Furthermore, fuller's earth clays comprised of the mineral montmorillomite and alumino silicates have been used in connection with animal litters, alone or in combination with other substances including zeolitic substances.

In most applications, the fuller's earth clay is calcined by heating it to a finishing temperature of more than 180°C to remove all of the free moisture and a portion or all of the interstitial moisture of the clay. Clay heated to a finishing temperature higher than 180°C but less than 1000°C is generally known as calcined clay. In the case of attapulgite, a type of fuller's earth clay, the attapulgite is known as a low volatile material ("LVM") attapulgite. Such clays have no or a low amount of free moisture but some interstitial moisture. Fuller's earth clay heated to more than 1000°C has no free moisture and no interstitial moisture. Fuller's earth clays which are calcined by heating them to a finishing temperature of more than 180°C are non-colloidal. Non-colloidal clays are those that do not form colloids when dispersed in a liquid environment such as water. —^■

One disadvantage of the above-described fuller's earth clays when used as an animal litter is that they either do not form clumps when exposed to urine or, if they do, such clumps are not cohesive. The clumps, for example, formed by LVM attapulgite disintegrate completely when removed or dislodged. Another disadvantage is that they do not absorb the urine readily whereby the urine accumulates at the bottom of the litter box.

In order to improve the. clumping and absorbing properties of fuller's earth clay, the clay sometimes is partially calcined to remove all or most of the free moisture thereof by heating it to a finishing temperature of not more than 180°C, usually 120° to 150°C. Such clay is colloidal in that it forms a colloid when exposed to or dispersed in a liquid environment such as an aqueous environment. This partially calcined clay is generally known as heat treated clay. In the case of attapulgite, the partially calcined attapulgite is known as regular volatile material ("RVM") attapulgite. An animal litter being presently sold by Sanex Corporation of Houston, Texas, under the trademark Better Way utilizes heat treated clay and, more particularly, regular volatile material attapulgite. Although such clays readily absorb the urine and form strong and cohesive clumps that can be removed, the clumps are occasionally broken by the animal when the animal burrows in the litter or by the animal owner when he removes the clumps from the litter box. The inventor has found that mixing regular volatile material clay with granular zeolite in an animal litter results in a litter which also forms strong and cohesive clumps. The zeolite absorbs odors that form from the pieces of broken urine lumps that are too small to be readily removed. Heat treated clay such as regular volatile material attapulgite, heat treated bentonite or a mixture thereof has not been used in the past together with zeolites as an animal litter.

U.S. Patent No. 4,437,429 discloses an improved animal litter. The litter includes a non-colloidal fuller's earth clay and an effective amount of hydrated zeolite. It is well understood by those skilled in the art that a non-colloidal clay is a clay that is calcined by being heated to a finishing temperature of more than 180°C. The zeolite is a non-heat treated, naturally hydrated zeolite and is, preferably, in the form of chips. It is accepted and understood in the industry that chips are too large to pass through a 6 mesh sieve screen. One disadvantage of the animal litter disclosed in that patent is that the entire litter box must be disposed of after a certain period of time. Furthermore, another disadvantage is that the zeolites used in the form of chips are not as adsorbing as smaller zeolites such as granular zeolites.

U.S. Patent No. 4,437,429 makes reference to U.S. Patent Nos. 3,776,118 and 3,898,324 which disclose the use of a dried fine powder of zeolite mixed with other material to impart stability with the deodorizing accomplished by such material. Furthermore, that patent makes reference to U.S. Patent No. 4,085,704 herein zeolite serves as a vehicle for an odor control agent. Furthermore, U.S. Patent No. 4,437,429 makes reference to U.S. Patent No. 4,256,728 wherein zeolites act as a support for a deodorizing agent. Furthermore, U.S. Patent No. 4,437,429 makes reference to the fact that, prior to that patent, it was believed that for zeolites to be effective as an odor controlling agent in animal litter, 100 percent zeolite had to be used to effect ion exchange of the ammonia with the zeolite.

U.S. Patent No. 4,085,704 discloses an animal litter that produces a continuous, long lasting, uniform, slowly released odor control agent. It also suggests that highly absorbent materials, such as zeolites, are not desirable because they promote the oxidation or other reactions of the odor control agents thereby lessening the effectiveness and life of the agents. That patent also discusses the addition of non-colloidal fuller's earth in the animal litter to reduce the cost of the litter.

U.S. Patent No. 4,532,890 makes reference to Japanese Patent Application Laid-Open No. 129622/1982 that discloses the use of zeolite as a deodorizer. The zeolite is used as a granular material formed by molding pulverized zeolite to a uniform size. According to said patent both zeolite and bentonite that are used in the litter are non-colloidal mineral materials and are deposited at the bottom of septic tanks without being dissolved in water and without being subjected to microbial degradation.

U.S. Patent No. 4,506,628 makes reference to U.S. Patent No. 3,776,188 which discloses an animal litter which is either fly ash, a zeolite, or a combination thereof.

U.S. Patent No. 4,311,115 refers to zeolite as a deodorizing agent. According to that patent, zeolite poses a disposal problem.

Other than the disadvantages referred to hereinabove, one major disadvantage of the use of zeolite as taught by the prior art is that the animal litter containing such zeolite does not clump after the litter is exposed to urine. According to the present invention, an animal litter is disclosed which contains zeolite of a particular size together with a colloidal, heat treated fuller's earth clay such as a regular volatile material attapulgite, heat treated bentonite or mixtures thereof. The animal litter clumps easily whereby the clumped animal litter can be easily removed and disposed of without necessitating the disposal of the entire box. Furthermore, according to the present invention, an animal litter comprised of zeolite only is disclosed. The litter forms clumps.

These and other objects and advantages of the present invention will become readily apparent from the following description. SUMMARY OF THE INVENTION

The present invention discloses an animal litter containing a zeolite together with a colloidal, heat treated fuller's earth clay derived by partially calcining a fuller's earth clay by heating it to a finishing temperature of not more than 180°C. The zeolite is of 6/225 mesh size and preferably of 10/30 mesh size. The preferred clay is a regular volatile material attapulgite, a heat treated sodium bentonite or mixtures thereof. Preferably, the mixture includes less than twenty-five (25) weight percent zeolites and, most preferably, about sixteen (16) to seventeen (17) weight percent. Furthermore, preferably, the free moisture of the zeolite in the mixture is about ten (10) weight percent and the free moisture of the clay is fifteen (15) to twenty (20) weight percent.

The present invention also discloses an animal litter comprised solely of zeolite of 6/225 mesh size. The free moisture content of the zeolite is in the range of about 7 to 10 weight percent and, preferably, about 10 weight percent. DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the present invention an improved animal litter is formed by mixing a zeolitic substance with a colloidal fuller's earth clay. The clay is a heat treated clay as described above in the background section. The animal litter forms strong and cohesive clumps after being exposed to an aqueous substance such as urine. The clumps are easily removable from the litter box and are disposed of accordingly. Furthermore, according to the present invention, an animal litter is disclosed comprised solely of zeolite. The size and the moisture content of the zeolite are two critical factors that determine the use of the zeolite alone as an animal litter.

Certain terms are used herein to quantify and describe the water content of the zeolites and the clays including the terms free moisture, combined or interstitial moisture, structural moisture, and total moisture. As used herein, free moisture is the amount of water being physically adsorbed by the compound, i.e., the zeolite or the clay; combined or interstitial moisture is the_. amount of water being bound in the matrix of the compound; structural moisture is the amount of water which is chemically bonded to the compound; and total moisture is the aggregate of the free moisture and the combined moisture. The free moisture of a compound is expressed herein as a weight percentage of the total weigh of the zeolite compound including its combined moisture and its structural moisture. For example, if, in a zeolite, the free moisture is 7 grams, the interstitial moisture is 3 grams, the structural moisture is 2 grams and the weight of the zeolite without the free moisture, the interstitial moisture and the structural moisture is 88 grams, the free moisture is 7 weight percent.

The clays and zeolites used herein are offered commercially in a broad range of particle sizes. Particle sizes are measured herein by sieve screen mesh sizes of the U.S. Standard Screen Series (ASTM Specification E-ll-70 values) . When two mesh sizes are used together and separated by a virgule ("/") , the first listed mesh size designates' passage of the material through such mesh size and the second listed, larger-numbered mesh size designates retention of the _material by such mesh size. For example, use of "8/16" indicates passage through an 8 mesh screen and retention by a 16 mesh screen. Similarly, use of a material or particles being of a "8/16 mesh size" refers to all material or particles whose size is such that they pass through an 8 mesh screen but are retained by a 16 mesh screen. Alternatively, it refers to all material or particles whose size is smaller than 8 mesh but larger than 16 mesh. (a) Animal Litter Containing Zeolite and Clav

Any zeolite can be used in the present invention together with the clays described below to form an animal litter in accordance with the present invention. It is preferred, however, that the zeolite be a non-heat treated, naturally occurring and naturally hydrated zeolite. An example of a zeolite which is suitable for use in accordance with the present invention is clinoptilolite. The zeolite absorbs odors and, when used in sufficient amounts, it causes the litter to have a desirable pink color.

For a description of the zeolites, their names, and their formulas, reference is made to U. S. Patent No. 4,437,429 and to the Merck Index (10th Edition), Monogram 9922. These descriptions are incorporated in their entirety herein and made part hereof by reference.

It is essential that the zeolite be of a 6/225 mesh size. If the size of the zeolite is sufficiently large so as not to pass through a 6 mesh size, the animal litter does not clump and the odor absorbing properties of the litter are reduced. If the size of the zeolite is sufficiently small so as to pass through a 225 mesh screen, the zeolite is in powder form. The use of the powder zeolite in an animal litter is not practical because the zeolite is too dusty and the litter does not form the type of clumps desired by the present invention. It is preferred that the zeolite be of 10/30 mesh size.

In general, one may practice the invention by using any zeolite with a low or high free moisture, as long as the water content is not so high as to make the handling of the litter impractical because of wetness. The preferred zeolite is naturally occurring and naturally available zeolite. Such zeolite is naturally hydrated to an original free moisture in the range of about 0 to 7 percent. Water may be added to increase its free moisture up to about 10 weight percent, the equilibrium point.

The clay that is combined with the zeolite to form the animal litter of the present invention is a heat treated fuller's earth clay such as RVM attapulgite, heat treated sodium bentonite or mixtures thereof derived from fuller's earth clay as described in the background of the invention. More particularly, such clay is derived by partially calcining naturally available fuller's earth clay by heating it to a finishing temperature of not more than 180°C, usually 120° to 150°C. When heat treated clay is removed from the oven, it has little or no free moisture. For example, when the regular volatile material attapulgite is removed from the oven, its free moisture is negligible, if not zero. After it is exposed to the humidity of the atmosphere, it adsorbs water and its free moisture is normally raised to the range of 3 to 5 percent. Sometimes, in a very humid environment, the free moisture of the attapulgite may reach as high as 7 percent. The free moisture of the heat treated clay may be increased to more than 15 weight percent by adding water thereto. The free moisture, however, should not be increased to more than 25 weight percent so as not to make the clay very wet and difficult to handle. The heat treated fuller's earth clay is colloidal, i.e. it forms colloids when exposed to a liquid such as water.

Fuller's earth clays are material found in the ground. They are composed primarily of hydrous aluminum silicates. They also contain small amounts of non-clay material. Examples of fuller's earth clays include montmorillonite, kaolin, illite, halloysite, vermiculite, sepiolite, bentonite, and attapulgite. For a more detailed description of fuller's earth clays, reference is made to U.S. Patent No. 4,459,368. That description is incorporated herein and is made part hereof by reference. In the present invention, the most preferred heat treated fuller's earth clays are regular volatile material attapulgite, a heat treated sodium bentonite or mixtures thereof.

The particle size of the clay may vary. The clays, however, are usually available in 8/16, 16/30, 24/48, 20/60, 30/60 or 60/90 and smaller mesh sizes. Accordingly, the clay particles may be of 8/90 mesh size. The preferred mesh size is 20/60 and the most preferred is 30/60.

Although the clay and the zeolite may be mixed in any proportions to form an animal litter in accordance with the present invention, the preferred mixture contains less than twenty five (25) weight percent zeolite, and most preferably about sixteen (16) to seventeen (17) weight percent zeolite. . When used in such amount, the zeolite absorbs odors, the litter forms cohesive clumps and the litter has a desirable pink color. Furthermore, because the level of the free moisture content of the zeolite and the clay in the mixture affects the clumping of the litter, it is mostly preferred that the mixture be sufficiently hydrated so that, in the mixture, the free moisture of the zeolite is about ten (10) percent (the equilibrium point) and the free moisture of the clay is in the range of about fifteen (15) to twenty (20) weight percent. The material may be hydrated either before or after the mixing of the zeolite with the clay.

The use of the zeolite together with the clays, as described above, has resulted in the unexpected result of forming an animal litter which has unexpected properties, i.e. the ability to form clumps which are strong and cohesive and easily removable from the cat litter box while retarding the ammonia odor of the litter.

(b) Zeolite Used Alone as an Animal Litter

In another embodiment of the present invention, zeolite is used alone as an animal litter. In that case, it is essential that the zeolite be naturally occurring zeolite of 6/225 mesh size. Furthermore, it is essential that the zeolite have a free moisture in the range of 7 to 10 weight percent and, more preferably, a free moisture of about 10 weight percent. Zeolite with such characteristics forms clumps when exposed to urine. This is an unexpected property. Those clumps, however, are not as cohesive as the clumps formed by the litter which contains zeolite and fuller's earth clays, as described above.

While the invention has been described herein in connection with certain preferred embodiments, modifications thereof can be made by one skilled in the art without departing from the spirit of the invention.

Claims

What is claimed is:

1. An animal litter, comprising; a zeolite; and a colloidal clay.

2. An animal litter according to claim 1 wherein the clay is a heat treated fuller's earth clay.

3. An animal litter according to claim 1 wherein the clay is a partially calcined clay.

4. An animal litter according to claim 1 wherein the clay is derived by heating a fuller's earth clay to a finishing temperature of not more than 180-C.

5. An animal litter according to claim 1 wherein the zeolite is of a 6/225 mesh size.

6. An animal litter according to claim 5 wherein the zeolite is of 10/30 mesh size.

7. An animal litter according to claim 1 wherein the amount of zeolite is less than about 25 weight percent of the aggregate weight of the zeolite and the clay and the free moisture of the zeolite is in the range of about 7 to about 10 weight percent.

8. An animal litter according to claim 7 wherein the zeolite has a free moisture of about 10 percent.

9. An animal litter according to claim 1 wherein the zeolite is of 30/225 mesh size and the free moisture of the zeolite is in the range of about 7 to about 10 weight percent.

10. An animal litter according to claim 9 wherein the free moisture of the zeolite is about 10 weight percent.

11. An animal litter according to claim 1 wherein the free moisture of the clay is in the range of fifteen (15) to twenty (20) weight percent.

12. An animal litter according to claim 1 wherein the clay is of a 20/60 mesh size.

13. An animal litter according to claim 12 wherein the clay is of a 30/60 mesh size.

14. An animal litter according to claim 1 wherein the zeolite is naturally available and naturally hydrated zeolite.

15. An animal litter according to claim l wherein the clay is a regular volatile material attapulgite.

16. An animal litter according to claim 1 wherein the clay is a heat treated bentonite.

17. An animal litter according to claim l wherein the free moisture of the zeolite is in the range of about 7 to about 10 weight percent.

18. An animal litter, comprising: a zeolite; and a fuller's earth clay treated to a finishing temperature of no more than 180°C.

19. An animal litter, comprising: a zeolite; and a partially calcined fuller's earth clay.

20. An animal litter comprising a zeolite alone, the zeolite being of a 6/225 mesh.

21. An animal litter according to claim 20 wherein the zeolite is naturally available and naturally hydrated zeolite.

22. An animal litter according to claim 20 wherein the free moisture of the zeolite is in the range of about 7 to about 10 weight percent.

23. An animal litter according to claim 20 wherein the free moisture of the zeolite is about 10 weight percent.

24. An animal litter according to claim 22 wherein the zeolite is a naturally occurring zeolite with moisture added to it to increase its original free moisture.

25. An animal litter according to claim 4 wherein the clay is derived by heating the fuller's earth clay to a finishing temperature of 120° to 150-C.

26. An animal litter according to claim 1 wherein the clay includes an attapulgite and a bentonite.

27. An animal litter according to claim 16 wherein the bentonite is sodium bentonite.

28. An animal litter according to claim 1 wherein the free moisture of the zeolite is about 10 weight percent and the free moisture of the clay is in the range of about fifteen (15) to twenty (20) weight percent.