Animal litter containing a water-swellable clay, carboxymethylcellulose, and siliceous coated bicarbonate particles

There is disclosed an animal litter composition comprising 1) a particulate, water absorbent clayey component, e.g., sodium bentonite, containing at least one water-swellable clay mineral, e.g. montmorillonite; 2) a water-soluble salt, e.g., a sodium salt of a carboxymethylcellulose; and optionally (3) a solid particulate deodorizing additive component comprising sodium bicarbonate (SBC) or potassium bicarbonate (KBC), the particles of which are substantially coated with a mineral oil, mixed with a powdered siliceous material, e.g., expanded perlite, having a bulk density significantly lower than the density of SBC or KBC, the coated particles of SBC or KBC being stably adhered to and agglomerated with the particles of the siliceous material. On contact with a waste aqueous liquid such as urine, the litter composition forms clumps which can be easily removed from the remainder of the litter and can be disposed of with relatively little disintegration.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to novel clumpable animal litters. 
2. Information Disclosure Statement including Description of Related Art 
The following information is disclosed in accordance with the provisions of 
37 CFR 1.56, 1.97 and 1.98. 
As is well-known, many species of animals and birds are raised and/or kept 
by people for various purposes, e.g., as pets; for the production of 
valuable products such as food or furs; or for experimental purposes. A 
major problem connected with the raising and/or keeping of animals is the 
disposition of their waste excretions, mainly urine and feces. Whether the 
animal or bird is caged, in which case its waste is deposited on the floor 
of the cage, or allowed to roam free but is trained to deposit its waste 
in a particular receptacle, a "litter" material is generally employed 
which is capable of absorbing the liquid portion of waste excretions, 
primarily urine and the excess liquid of fecal matter. 
Of particular interest as the basic component of animal litters are the 
clayey soils or comminuted rocks, e.g. the sodium bentonites, comprising 
at least one water-swellable clay mineral in the montmorillonite clay 
family, since these materials have the ability to clump and harden after 
contact with an aqueous liquid such as urine. This facilitates the removal 
of only the soiled portion of the litter in a litter box or cage during 
cleaning without the necessity of removing all the litter. However, while 
the water absorption properties of litters based on water-swellable clay 
make them more effective in reducing the mess of animal waste excretions 
between cleanings, due to the tendency of the clay to form clumps, it has 
been found that such clumps often tend to disintegrate before proper 
disposal. This decreases the effectiveness of the cleaning process. 
With regard to the odor problem connected with the use of animal litters, 
various deodorizing agents have been recommended for use in such litters, 
including sodium bicarbonate (SBC). However, when SBC is utilized in the 
form of an unmodified powder as a deodorizing agent in animal litter, it 
tends to "wick" and dissolve in the aqueous phase of any animal waste 
products present, in which dissolved state it does not exert any 
deodorizing effect. Furthermore, due to its relatively high density, it 
tends to sink to the bottom of any litter composition present in the cage 
or litter box. To overcome these disadvantages, it has been proposed that 
the SBC be utilized in the animal litter in encapsulated form. However, 
the preparation of encapsulated SBC is an expensive procedure which 
renders the employment of SBC in this form impractical for many 
applications. 
The following prior art references illustrate aspects of the technology of 
animal litter preparation, and, in particular, disclose the use of clays 
in such litters. 
U.S. Pat. No. 3,765,371 issued Oct. 16, 1973 to Fisher, discloses a foamed 
plastic for absorbing and/or adsorbing animal waste products and also 
identifies clay and bentonites as previously used animal litters. 
U.S. Pat. Nos. 4,275,684 issued Jun. 30, 1981 and 4,395,357 issued Jul. 26, 
1983 to Kramer et al., disclose calcium silicate as an animal litter box 
absorbent material, and state that clay minerals, e.g. sepiolites, are 
known litters. 
U.S. Pat. No. 4,315,761 issued Feb. 16, 1982 to Larrson et al., teaches the 
use of aerated or foamed concrete to absorb animal waste products and 
facilitate the removal of excrement from a litter box, and also discloses 
that "porous granulates of burnt expanded clay" is known for use as a 
urine absorbent. 
U.S. Pat. No. 4,494,481 issued Jan. 22, 1985 to Rodriguez et al., discloses 
the addition of a soluble salt of a transition metal from Group Ib or IIb 
of the Periodic Table to a conventional litter composition to prevent the 
development of urine odors, and also identifies "clay such as . . . 
montmorillonites or bentonites" as suitable for use as an animal litter. 
U.S. Pat. No. 4,570,573 issued Feb. 18, 1986 to Lohman, discloses an animal 
litter composition containing 60-94 wt. % of paper, 1-35 wt. % of gypsum, 
and 3-12% of water, and also states that clay, fuller's earth, and 
vermiculite are employed in cat litter compositions. 
U.S. Pat. No. 4,638,763 issued Jan. 27, 1987 to Greenberg, teaches the 
addition of sodium sulfate to a litter box absorbent material to 
facilitate removal of solid absorbent material from the litter box, and 
teaches that clays such as montmorillonite and hectorite are suitable as 
absorbent material. 
U.S. Pat. No. 4,685,420 issued Aug. 11, 1987 to Stuart, discloses an animal 
litter composition comprising a water-absorbing polymer such as a 
polyacryate combined with a porous inert solid substrate such as clay. 
U.S. Pat. No. 5,000,115 issued Mar. 19, 1991 to Hughes, discloses the use 
of a water swellable bentonite clay as an absorbent litter material. The 
clay absorbs the liquids in animal waste which on contacting the clay 
agglomerates it into a stable mass easily separated from the unwetted and 
unsoiled portion of the composition. 
Pending application Serial No. 08/056,511, filed May 3, 1993, discloses and 
claims the deodorizing additive which may be used in the litter 
compositions of this invention. 
Pending application Serial No. 08/056,629, filed May 3, 1993, discloses and 
claims animal litter compositions containing a water-swellable clay and 
the deodorizing additive component which may be used in the litter 
compositions of this invention. 
SUMMARY OF THE INVENTION 
In accordance with this invention, there is provided an animal litter 
comprising (1) a particulate water-absorbent clayey component, e.g. a 
clayey soil or comminuted rock such as a sodium bentonite, containing at 
least one water-swellable clay mineral, e.g. montmorillonite; and (2) a 
water-soluble salt of carboxymethylcellulose (CMC). As an optional 
component, the litter composition may also contain (3) as a deodorizing 
additive component for the clayey component, a solid particulate 
composition comprising sodium bicarbonate (SBC) or potassium bicarbonate 
(KBC), the particles of which are substantially coated with a mineral oil, 
blended with a powdered siliceous material, e.g., expanded perlite, having 
a bulk density significantly lower than the density of SBC or KBC, the 
coated particles of SBC or KBC being stably adhered to and agglomerated 
with the particles of the siliceous material. 
Because of the water swellability of the clay mineral contained in the 
clayey component and the presence of the CMC salt, the litter tends to 
form hardened clumps wherever it is contacted with an aqueous liquid such 
as urine. Moreover such clumps can be easily scooped up from the litter 
box or cage without removing the portions of the litter which have not 
been contacted with the urine, and can be disposed of with relatively 
little disintegration. The improvement in the resistance to disintegration 
of the clumps formed by the litters of this invention when contacted with 
an aqueous liquid such as animal urine is apparently due to some unobvious 
interaction between the water-swellable clay and the CMC salt in the 
presence of water since the same effect is not necessarily present when a 
CMC salt is added to a litter composition containing a water absorbent 
material other than a water-swellable clay. 
If the deodorizing additive component is also present in the litter 
composition, any urine odors which tend to form between removal of the 
urine containing clumps or due to small clumps or traces of urine which 
are not removed with the larger clumps, tend to be eliminated or minimized 
by the SBC or KBC in such additive component. Since the SBC or KBC 
particles in the deodorizing additive component present in the litters of 
this invention are largely coated with mineral oil and are agglomerated 
with the siliceous material, they have little or no tendency to wick and 
dissolve into the aqueous phase of the animal waste products deposited in 
the litter. Moreover, the large effect of the mineral oil, due to its 
capillarity, surface tension and viscosity, in causing the SBC or KBC to 
adhere to and agglomerate with the lower bulk density siliceous material, 
results in a reduction of the overall density of the particles containing 
SBC or KBC in the composition of the deodorizing additive component, so 
that such density is substantially lower than that of the SBC or KBC 
itself. Thus, there is a much smaller tendency for the particles of the 
deodorizing additive component of the litter to sink to the bottom of the 
litter box or cage containing the litter than there is when pure SBC or 
KBC is added. The additive component therefore provides means for the SBC 
or KBC to exert its deodorizing effect while dispersed throughout the 
litter, even in the presence of a considerable amount of aqueous liquid 
such as urine. 
Due to the necessity for the SBC or KBC in the deodorizing additive 
component which may be employed in the animal litter of this invention to 
be thoroughly coated with mineral oil and to be efficiently agglomerated 
with the particles of siliceous material, the method of preparation of the 
additive component is somewhat significant. Thus, in most cases, the pure 
SBC or KBC must be blended with sufficient mineral oil to substantially 
coat the particles while still maintaining a powdery consistency, and the 
powder of coated particles is then blended with a powder of the siliceous 
material to obtain a powder composition composed of stable agglomerates of 
coated SBC or KBC and siliceous material. 
DETAILED DESCRIPTION OF THE INVENTION 
As stated, the water-absorbent clayey component of the animal litters of 
this invention may be, for example, a clayey soil or comminuted rock 
containing at least one water swellable clay mineral. Such clay mineral 
may be, for example, a montmorillonoid or smectite, having a three-layer, 
sheet structure crystal lattice with two layers of silicon/oxygen 
tetrahedrons between which is a central layer of aluminum and/or 
magnesium/oxygen dioctahedrons or trioctahedrons. Part of the silicon in 
the tetrahedral layers may be substituted with aluminum and part of the 
aluminum and/or magnesium in the central octahedral layer may be 
substituted with other elements such as lithium, chromium, zinc, or iron. 
Contemplated montmorillonoid clay minerals are montmorillonite and 
nontronite containing a dioctahedral central layer, and hectorite, 
saponite, and sauconite containing a trioctohedral central layer. 
When the foregoing montmorillonoid clay minerals are contacted with water 
or water vapor, the water molecules penetrate between the layers causing 
interlayer or intracrystalline swelling and expansion of the entire 
lattice. This causes the particles of clayey component in the animal 
litter to agglomerate thus facilitating the removal of only that portion 
of the litter which is swelled by urine or other aqueous waste liquid. 
The clayey component may have a particle size in the range, for example, of 
about 300 to 2500 microns (about 50 to 8 U.S. mesh size), preferably about 
420 to 840 microns (about 40 to 20 U.S. mesh size). 
The preferred clayey component of the animal litter of the invention is a 
comminuted bentonite, more preferably a sodium bentonite, which contains a 
preponderant amount of montmorillonite clay mineral Other clayey 
components which may be used are the attapulgite clays and/or mixtures of 
bentonites from various sources. 
The base clayey component may be present in an amount, for example, of 
about 80 to 98 wt. %, preferably about 90 to 95 wt. % based on the weight 
of the litter composition. 
The water-soluble CMC salt contemplated in the litter compositions of this 
invention is, for example an alkali metal salt, e.g. a sodium or potassium 
salt, preferably a sodium salt of a CMC having a number average molecular 
weight of, for example about 200 to 2000, preferably about 700 to 800. The 
CMC salt may be present in an amount, for example, of about 0.1 to 2.0 wt. 
%, preferably about 0.25 to 1.0 wt. %, based on the weight of the litter 
composition. 
In general, any commercial grade of SBC or KBC may be used in preparing the 
deodorizing additive component which may be optionally present in the 
compositions of this invention. Thus, the particles of SBC or KBC may be 
within the range of about 20 to 400 U.S. mesh size, preferably about 40 to 
140 U.S. mesh size, and may have an SBC or KBC purity of at least about 90 
wt. % preferably at least about 99 wt. %. The SBC or KBC is usually 
present in the deodorizing additive component in an amount of about 80 to 
99 wt. % preferably about 95 to 98 wt. %, based on the total weight of the 
additive component. 
Any conventional and available mineral oil may be used in preparing the 
deodorizing additive component, e.g., those having a density of about 
0.830 to 0.905 g/cc. at 15.6.degree. C. and a viscosity of about 3 to 80 
centistokes at 40.degree. C. The amount of mineral oil employed is 
generally in the range of about 0.1 to 2.0 wt. %, preferably about 0.5 to 
1.0 wt. % based on the weight of SBC or KBC. 
The powdered siliceous material having a bulk density significantly lower 
than SBC or KBC may be obtained, for example, from a type of glassy 
igneous rock, e.g., a rhyolitic glass such as perlite, comprising hydrated 
silica and containing spheroidal and convoluted concentric cracks causing 
it to break up into small pearlike masses or pebbles. When this type of 
material is crushed and "expanded," i.e., heated to a temperature above 
that at which its water of hydration is liberated, it forms particles of 
thin spherical or ellipsoidal shells and their fragments and other scaly 
or flaky siliceous particles which may be used in the compositions of this 
invention. Expanded perlite is the preferred siliceous material for use in 
this invention. 
Other specific siliceous materials which may be utilized in the deodorizing 
additive component which may be present in the animal litters of this 
invention are rhyolitic glasses other than perlite and phyllosilicates 
containing water of hydration, e.g., vermiculite, which have been 
subjected to expansion. As is the case with perlite, heating these 
materials to a temperature above that at which their water of hydration is 
liberated causes them to expand physically to a substantial degree 
resulting in an appreciable decrease in their bulk density. 
The siliceous material, e.g., expanded perlite, utilized in the deodorizing 
additive component may have a bulk density in the range of, for example, 
50 to 300 g/1 preferably about 70 to 150 g/l and a particle size, for 
example, of about 20 to 400 U.S. mesh size, preferably about 50 to 200 
U.S. mesh size. It may be present in the deodorizing additive component in 
an amount, for example, of about 0.5 to 20 wt. %, preferably about 1 to 5 
wt. %, based on the weight of the final deodorizing additive component. 
Within the foregoing ranges, the weight percent of siliceous material in 
the deodorizing additive component may be adjusted such that the density 
of the particles in such component is closer to that of the particles of 
the clayey component of the litter for which the additive is intended than 
the density of pure SBC or KBC. This has the effect of reducing the 
tendency of the deodorizing particles to settle to the bottom of the mass 
of litter in the litter box or cage. 
The deodorizing additive component, if utilized, may be present in the 
litter composition in an amount, for example, of about 2 to 20 wt. %, 
preferably about 5 to 10 wt. %, based on the weight of the litter 
composition. 
The litter compositions of this invention may also optionally contain a 
fragrance component. This may be a powdery "fragrance preblend" comprising 
a pleasant smelling oily liquid or "perfume oil" absorbed on particles of 
a fragrance carrier having a high surface to volume ratio. The perfume oil 
may comprise one or more essential or synthetic oils which are well-known 
in the art as providing a pleasant odor to the composition containing them 
and also as having the capability of somewhat masking unpleasant odors. 
The fragrance carrier may be any of a group of siliceous and other 
materials also well-known in the art as having a high surface to volume 
ratio and as being able to absorb perfume oils efficiently while 
maintaining their powdery consistency, e.g., dimorphous silicas or 
starches. The perfume oil may be present in the fragrance preblend in an 
amount, for example, of about 25 to 75 wt. % based on the total weight of 
preblend, and the particle size of fragrance carrier and preblend may be 
in the range, for example, of 50 to 400 U.S. mesh size. The fragrance 
preblend may be blended into the litter composition at any point separate 
from the initial blending of materials making up the deodorizing additive 
component if such component is utilized, and may be present in the final 
litter composition in an amount, for example, of about 0.5 to 3.0 wt. % 
based on the weight of the total composition. 
The fragrance may also be utilized in encapsulated form or as a spray dried 
component. 
The litter composition may also optionally contain zinc oxide (ZnO) which 
exerts a bactericidal action on the waste products in the litter. Since at 
least some of the foul odors of urine and fecal matter over a period of 
time is caused by the bacterial breakdown of the components of such 
matter, the anti-bacterial action of the ZnO results in a reduction of the 
generation of such odors. If employed, the ZnO may be added separately 
with the other components in the preparation of the litter or included in 
the preparation of the deodorizing additive component if such component is 
employed. The ZnO may be present in an amount, for example, of about 0.1 
to 1 wt. % of the litter composition, or about 5 to 10 wt. % of the 
deodorizing additive component of the ZnO is incorporated in the 
preparation of such component subsequently used in the litter composition. 
The ZnO may have a primary (unagglomerated) particle size of about 5 
nanometers to 300 microns, preferably about 5 nanometers to 10 microns. 
In preparing the deodorizing additive component if such is intended to be 
utilized in the litter compositions of this invention, the SBC or KBC and 
mineral oil are separately blended, e.g., by adding the SBC or KBC to a 
mixer and spraying the mineral oil into the mixer while the SBC or KBC is 
being agitated. After all the mineral oil is added, the blending procedure 
may be continued for a period, for example, of about 5 to 20 min. The 
siliceous material having a relatively low bulk density, e.g., expanded 
perlite, may then be added to the mixer where it is blended with the SBC 
or KBC/mineral oil mixture for a period of, for example, about 5 to 20 
minutes. 
If a fragrance is intended to be present, a fragrance preblend may be 
separately prepared, e.g., by adding a portion of the fragrance carrier to 
a mixer, initiating spraying of the perfume oil into the mixer while the 
remainder of the fragrance carrier is added, and continuing blending until 
a lump-free consistent powder is obtained. The blending period for 
preparation of the fragrance preblend may be, for example, about 10 to 60 
min. 
As stated, the fragrance and/or ZnO, if used, may be incorporated in the 
litter composition at any point separate from the initial blending of SBC 
or KBC, mineral oil, and siliceous material in the preparation of the 
deodorizing additive component if such component is intended to be present 
in the litter composition. For example, the ZnO and then the fragrance may 
be added to the mixture of SBC or KBC, mineral oil and siliceous material 
during the preparation of the deodorizing additive component, and blending 
continued, e.g., for a period of about 5 to 20 min. for each component, 
until the final deodorizing additive component is obtained. Alternatively, 
the CMC salt, fragrance if used, and ZnO if used, may be blended with the 
clayey component before the latter is blended with the deodorizing 
additive component if used, or they may be blended with the mixture of 
clayey component and deodorizing additive component after these two 
components are blended. 
The foregoing blending procedures may be carried out in any conventional 
equipment intended for the blending of a particulate solid material with 
other solid materials or liquids. Examples of suitable equipment are 
ribbon blenders, V-shell blenders, Marion mixers, and Norda mixers. 
The litter compositions of this invention may be used for a wide variety of 
animals and birds, e.g., uncaged household pets such as cats and dogs, 
particularly puppies too young to be walked, caged pets such as hamsters, 
gerbils and rabbits, caged laboratory animals such as guinea pigs, mice, 
rats and monkeys, animals raised for fur such as mink, barnyard birds such 
as chickens, ducks and geese, and pet birds such as parrots, parakeets, 
canaries and pigeons. 
In addition to the components described previously, the litter composition 
of this invention may contain other components for various purposes, e.g., 
disinfectants and colorants. 
The compositions of this invention are particularly suitable for use as cat 
litters.

The invention is further by the following examples. All parts are by 
weight. 
EXAMPLE 1 
This example shows the preparation of a litter composition of this 
invention containing a deodorizing additive component but no fragrance. 
The deodorizing additive component was first prepared as follows: 
Sodium bicarbonate (SBC) having a purity of over 99% and a particle size in 
the range of about 40 to 140 U.S. mesh size was charged in an amount of 96 
parts to a ribbon blender while 0.5 -2.0 parts of mineral oil having a 
density of about 0.850 g/cc at 15.6.degree. C. and a viscosity of about 12 
centistokes at 40.degree. C. was being sprayed into the blender. The 
charging of the SBC and mineral oil was accomplished in 31/2 min. and 
blending of the two components was continued for another 8 min. Two parts 
of expanded perlite having a bulk density of about 100 g/l and particle 
size in the range of about 50 to 200 U.S. mesh size was then added to the 
blender in the course of 21/2 min. and blending was continued for 5 
additional minutes. 
The foregoing deodorizing additive component is blended with 90 wt. % of 
comminuted sodium bentonite having a particle size distribution of about 
20 to 40 U.S. mesh size, and 1 wt. % of a sodium CMC having a number 
average molecular weight of about 800. 
EXAMPLE 2 
This example illustrates the preparation of a litter composition of this 
invention containing a deodorizing additive composition which in turn 
contains a fragrance. 
A fragrance preblend was prepared by first charging a ribbon blender with 
0.3 part of "Sipermat 22" dimorphous silica fragrance carrier and then 
spraying into the blender 0.6 part of a perfume oil known in the art as 
having the property of at least partially masking unpleasant odors while 
adding an additional 0.3 part of fragrance carrier. Blending was continued 
for one hour from the addition of the perfume oil to obtain a finished 
fragrance preblend. 
The fragrance preblend was then added to the additive composition prepared 
in another ribbon blender as described in Example 1 and blending was 
continued for 11 min. to obtain the final deodorizing additive component 
containing fragrance. The deodorizing additive component is then blended 
with a base sodium bentonite component and a sodium CMC as described in 
Example 1. 
The litters of both Examples 1 and 2 are particularly suitable as cat 
litters but can also be used for other animals and birds. However used, 
the portions of the litter contacted with urine or other waste liquids 
form agglomerated clumps which can be easily scooped up and separated from 
the remainder of the litter not contacted with urine and which do not tend 
to disintegrate before disposal. Furthermore, if the deodorizing additive 
component is present, the litter does not emit urine or other foul odors 
between cleanups as readily as other litters which do not contain such 
component.