Combined odor controlling animal litter

The invention provides, in one embodiment, an odor controlling animal litter comprising: (a) adsorbent or absorbent particles; and (b) an ammonia-controlling-effective amount of (i) pine oil and (ii) boric acid applied onto the particles. The litter can also include further adjuncts, such as fragrances, other antimicrobial additives, and the like.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an animal litter at least a portion of which has 
been contacted with an antimicrobially-effective amount of pine oil 
combined with an effective amount of boric acid, or a boron-containing 
material having an equivalent boron level. 
2. Brief Description of Related Art 
Because of the growing number of domestic animals used as house pets, there 
is a need for litters so that animals may micturate, void or otherwise 
eliminate liquid or solid waste indoors in a controlled location. However, 
inevitably, waste build-up leads to malodor production. 
Pine oil has been suggested in the prior art as a fragrance only, for 
application to a litter. For example, Frazier, U.S. Pat. No. 4,085,704, 
discloses the impregnation of an inorganic carrier vehicle, such as silica 
gel or mullite. Also, Colborn, et al., U.S. Pat. No. 4,407,231 (of common 
assignment) discloses the microencapsulation of fragrances, including pine 
oil, via a polymeric slurry, which is then sprayed onto a portion of 
litter particles, and dried. 
Miller et al., U.S. Pat. No. 3,675,625, disclose a litter which is 
"activated" by heating and then contacted with an odor control agent, such 
as pine oil, citrus oil, camphor or the like. 
Still further, it has been suggested that a borax/boric acid mixture at a 
pH of 4-4.5 could be added to a cellulose litter containing a pheromone. 
(Christianson, U.S. Pat. No. 4,263,873). Yet further, in Ratcliff et al., 
commonly assigned U.S. patent application Ser. No. 07/208,953, filed Jun. 
17, 1988 now U.S. Pat. No. 4,949,672, an odor control animal litter has 
been disclosed and has claimed a clay-based, particulate substrate to 
which has been applied a liquid carrier containing a boron-containing 
material at a critical level of at least 0.06% equivalent boron. 
However, the art does not disclose, teach, suggest or recognize the 
combination of pine oil and boric acid as a dual odor controlling system 
when applied to animal litters. Finally, the art has not taught, disclosed 
or suggested that either or both of these odor controlling materials can 
be used in conjunction with aluminum salts for effective ammonia control. 
SUMMARY OF THE INVENTION 
The invention provides an odor controlling animal litter comprising 
(a) adsorbent or absorbent particles; and 
(b) an ammonia-controlling-effective odor controlling combination of (i) an 
effective amount of pine oil and (ii) an effective amount of boric acid, 
or its equivalent, preferably carried onto said particles via a liquid 
dispersion. 
The invention also comprises a method of delivering an 
ammonia-controlling-effective amount of an odor controlling agent to an 
animal litter which method comprises contacting the litter, with an 
aqueous dispersion of a mixture of an ammonia-controlling-effective amount 
of pine oil and boric acid or its equivalent. 
It is therefore an objective of this invention to provide an odor 
controlling animal litter. 
It is a further objective of this invention to provide a low cost, highly 
effective odor controlling material for animal litter. 
It is a still further object of this invention to effectively disperse 
consistently the odor controlling agents, pine oil combined with boric 
acid (or its equivalent), onto the litter particles so as to maximize the 
odor controlling benefit. 
It is still another object of this invention to combine pine oil and boric 
acid (or its equivalent) as an odor controlling system, preferably by 
using a liquid carrier for simultaneous delivery, on an animal litter. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention provides an odor controlling animal litter for use by 
domestic animals. It is well understood that soiled animal litters become 
malodorous due to the decomposition of nitrogenous products present in 
animal waste. The breakdown of these nitrogenous products into ammonia is 
believed to be mediated by enzymes produced by many bacteria and other 
microflora. As an example, urease acts as a catalyst to break down urea 
into ammonia via the following chemical pathway. 
##STR1## 
Thus, odor formation can be controlled or mitigated through the use of 
materials which are toxic to bacteria and other microflora which produce 
enzymes which decompose nitrogenous products. 
It has been surprisingly discovered that pine oil can, in combination with 
boric acid, or its boron equivalent, in antimicrobially-effective amounts, 
control odor formation by controlling microbial decomposition of 
nitrogenous products, not merely by masking malodors. 
1. Pine-Oil Odor Controlling Agent: 
Pine oil is a complex blend of oils, alcohols, acids, esters, aldehydes and 
other organic compounds. These include terpenes, which include a large 
number of related alcohols or ketones. Some important constituents include 
terpineol, which is one of three isomeric alcohols having the basic 
molecular formula C.sub.10 H.sub.17 OH. Other important compounds include 
alpha- and beta-pinene (turpentine), abietic acid (rosin), and other 
isoprene derivatives. Further, the apparent fragrance or strength of such 
fragrance, in a particular pine oil is not necessarily correlatable to the 
particular pine oil's germicidal activity. 
Particularly effective pine oils appear to be Unipine 60 (Union Camp, which 
is believed to contain 61% terpene alcohols, 37% terpene hydrocarbons, 
remainder: moisture and miscellaneous) and Unipine 90 (Union Camp, about 
95% terpene alcohols, 4% terpene hydrocarbons, remainder: moisture and 
miscellaneous). Other concentrated products, which can contain up to 97% 
pure alpha-terpineol, have been used with success. In the present 
invention, the levels of pine oil as low as 0.1% (47% active) have been 
found to be effective odor control agents. Additionally, the range of pine 
oil that should be a ammonia-controlling-effective amount vary from about 
0.001 to 50% by weight of the composition, more preferably 0.05-25%, and 
most preferably 0.1-10%, by weight of the composition. 
As discussed in the background of the invention, above, at least three 
references have discussed the use of pine oil as a fragrance additive. 
However, two of the references (Frazier, U.S. Pat. No. 4,085,704; Colborn 
et al., U.S. Pat. No. 4,407,231) either impregnate pine oil in an 
inorganic, porous carrier vehicle, or completely encapsulate with an 
organic coating, so as to provide, respectively, a slow-release product, 
or one which does not release at all except by fracturing of the 
microcapsule. The third (Miller et al., U.S. Pat. No. 3,675,625), on the 
other hand, teaches that the pine oil must be added to litter under 
apparently anhydrous conditions to avoid the presence of water. None, 
however, teaches that pine oil combined with boric acid (or its 
equivalent) provide surprisingly effective ammonia control which is 
superior to that of pine oil alone (although pine oil alone can be an 
effective ammonia-controlling agent). Applicants, on the other hand, have 
surprisingly found that pine oil plus boric acid (or its equivalent) act 
as an odor controlling system for animal litters by preventing ammonia 
formation, rather than merely by masking odors. 
In the invention, it is preferred to deliver the pine oil and boric acid 
(or its equivalent) in a liquid vehicle onto at least a portion of the 
litter. This has the advantages of dispersing uniform amounts of the 
actives together and to control the amount of actives such that there is 
the maximum available for use. (However, it may also be possible to add 
the two components separately, depending on manufacturing conditions.) 
Because a relatively small amount of pine oil is being applied to the 
litter, uneven application could result unless a diluting medium were 
used. Water is very advantageous for use here because: it is an 
inexpensive medium and avoids the potential hazards of solvents. 
Additionally, it has the benefit of solubilizing the other component, 
boric acid. 
Accordingly, a key aspect of the invention is to contact the litter 
particles with an aqueous dispersion of water, the pine oil, the boric 
acid and a dispersion aid which uniformly disperses the materials in the 
water. The preferred dispersion aids are surfactants, although solvents 
and hydrotropes may be appropriate (but not as prefered). The surfactants 
are selected from anionic, nonionic, cationic, amphoteric surfactants, and 
mixtures thereof. Suitable surfactants may be found in Kirk-Othmer, 
Encyclopedia of Chemical Technology, 3rd Edition, Vol. 22, pages 346-387 
(1983), and McCutcheons's Detergents and Emulsifiers, North American 
Edition, 1983, both of which are incorporated herein by reference. 
Especially suitable surfactants are nonionic surfactants. Those which have 
an HLB of about 9-14, more preferably about 10-13, are favored. These 
include ethoxylated and propoxylated fatty alcohols, and ethoxylated and 
propoxylated alkyl phenols, having both with alkyl chains of about 7-16, 
more preferably about 8-13 carbons in length. A preferred ethoxylated 
alcohol is Neodol 91-8, a C.sub.9-11 fatty alcohol with about 8 moles of 
ethylene oxide per mole of alcohol, from Shell Chemical Company. A 
preferred ethoxylated alkyl phenol is Triton X-102, an ethoxylated 
octylphenol with about 10-12 moles of ethylene oxide per mole of alcohol. 
A mixture of Neodol 91-8 and Triton X-102 is also preferred. 
The surfactants can be selected and amounts used to give best results in 
dispersing the pine oil, giving good stability and obtaining lack of phase 
separation. It is preferred to use the surfactants in about 0.001 to 1% by 
weight of the treated litter, more preferably about 0.005 to 0.5% by 
weight of the treated litter. In the aqueous dispersion, the surfactant 
will comprise about 0.05 to 10%, more preferably 0.1 to 5% by weight of 
the dispersion. Concurrently, in the dispersion, the pine oil constituent 
will comprise about 0.03 to 50%, more preferably 2 to 25%, most preferably 
4 to 15%, by weight of the dispersion. Further, the surfactant will be in 
proportion to the pine oil at a ratio of about 0.01 to 1, more preferably 
0.1 to 1 of total surfactant to pine oil. 
2. Boron-Based Odor Control Additive: 
The other component of the invention is boric acid, or an equivalent boron 
compound providing the same amount of equivalent boron level. See, Kirk 
Othmer, Encyclopedia Chemical Technology. 3rd Ed., Vol. 4, pp. 71-77 
(1978), incorporated herein by reference. Although Applicants refer, from 
time to time herein, to commonly assigned U.S. application Ser. No. 
07/208,953, filed Jun. 17, 1988 now U.S. Pat. No. 4,949,672, said 
application is also incorporated by reference thereto as if fully set 
forth herein. 
Boric acid has the structure H.sub.3 BO.sub.3. Boric acid appears to 
provide multiple benefits in odor control by: (1) acting as a urease 
inhibitor, which controls odors by preventing enzymatic breakdown of urea; 
(2) apparently having bacteriostatic properties, which appear to help 
control odor by controlling the growth of bacteria which are responsible 
for production of the urease enzymes; and (3) possibly, lowering the pH of 
the litter thereby neutralizing basic material such as ammonia and amines 
of animal waste products. 
Borax (Na.sub.2 B.sub.4 O.sub.7 .times.10H.sub.2 O) is another suitable 
compound for use in the invention. Other boron-based compounds potentially 
suitable for use are disclosed in Kirk-Othmer, supra. pp. 67-109, said 
pages being incorporated herein by reference. In fact, as further 
discussed below, it appears that the active boron material in the 
preferred embodiment of this invention is actually a mixture of polyborate 
species, which is formed in situ in a liquid carrier; or it could be 
separately manufactured, dried, and used. Combinations of boric acid and 
borax, or other boron-based compounds, are also included in the invention. 
An odor controlling effective amount is defined as at least about 0.06% 
equivalent boron, more preferably at least greater than 0.06%. The 
preferred range varies from about 0.06 to about 50%, by weight of the 
composition. It is more specially preferred that 0.1 to 25%, and most 
preferably, about 0.1 to 10%, by weight of the composition be used. 
Assuming the critical level is attained, those skilled in the art will 
adjust the compositional levels to ensure effective odor control and cost 
effectiveness. 
In the following discussion, equivalent boron is defined as the amount of 
atomic boron delivered in wt. %. Equivalent boron is determined by 
calculating the amount of atomic boron in a boron-containing compound, and 
comparing it to another boron containing compound. E.g., assuming 1 g 
boric acid and 1 g borax, equivalent boron is: 
##EQU1## 
* Molecular weight of boric acid (H.sub.3 BO.sub.3) is 61.84. ** Atomic 
weight of boron is 10.81. In boric acid, there is only one atom of boron; 
in borax, there are four. *** Molecular weight of borax (Na.sub.2 B.sub.4 
O.sub.7 .times.10H.sub.2 O) is 381.37. 
Thus, borax has 64.87% of the amount of equivalent boron compared to 1 g 
boric acid. 
The boron-containing materials are powdered or comminuted solids, and are 
combined with a liquid carrier as disclosed in co-pending application Ser. 
No. 07/208,953, and demonstrated below, in the EXPERIMENTAL section. The 
carrier is water or water and a solvent, emulsifier or a hydrotrope, as 
necessary. It is essential to add the additive via liquid carrier to 
evenly distribute the additive to the litter material. 
3. Litter Materials: 
A wide variety of materials can be used for litters. For example, porous 
clays are readily adaptable for use as the absorbent substrates needed for 
litters. Suitable litters include aluminosilicates, such as attapulgite, 
bentonite, montmorillonite; fossilized plant materials; expanded perlites; 
zeolites; gypsum and other equivalent materials known to those skilled in 
the art. Sawdust, wood chips, paper or other cellulose based materials can 
be utilized. For instance, compacted paper, or processed, recycled pulp 
can be suitable for use, such as disclosed in Sokolowski et al., U.S. Pat. 
No. 4,619,862, and Fleischer et al., U.S. Pat. No. 4,621,011, both of 
which are incorporated herein by reference. Other litter materials can be 
used, such as fruit and vegetable wastes, e.g., Fry et al., U.S. Pat. No. 
3,923,005. The litter particles have an average particle diameter of 
50-5,600 microns, preferably about 100-500 microns. It is beneficial to 
obtain uniform sizing (such as by screening or sieving) and to have low 
amounts of fines, which will generate dust. Those skilled in the art will 
vary particle size so as to optimize absorbency/adsorbency, and to control 
dusting or tracking by the animal. 
4. Adjunct Materials: 
Aluminum salts can be used to obtain an additional benefit, amongst the 
most important adjunct materials. A favored aluminum salt is hydrated 
aluminum oxide (Al.sub.2 O.sub.3). A typical salt is a trihydrated 
aluminum salt/sodium chloride mixture. Although prior art has disclosed 
that aluminum salts have been used in animal bedding, see, e.g., Sawyer et 
al., U.S. Pat. No. 3,029,783, and Sawyer et al., U.S. Pat. No. 2,895,873, 
there is previously no recognition, teaching or suggestion that these 
aluminum salts could be combined with pine oil and/or boric acid to 
provide an odor control benefit. Also, certain polymers can be added which 
are so-called "superabsorbent" polymers to efficiently wick liquid wastes 
and entrap them, further bolstering odor control. Further adjunct 
materials that are suitable for use include dyes and pigments, such as 
suitably treated titanium dioxide. Additional and different germicides 
such as quaternary ammonium compounds, and certain 3-isothiazolones (sold 
under the trademark KATHON.RTM., Rohm and Haas), and chemical deodorants, 
such as sodium bicarbonate, can be utilized. Other odor controlling agents 
such as heavy metals (see, e.g., Rodriguez et al., U.S. Pat. No. 
4,494,481), enzyme inhibitors (see Heitfeld et al., U.S. patent 
application Ser. No. 07/223,502, filed Jul. 25, 1988, now U.S. Pat. No. 
4,957,063, of common assignment hereof, and incorporated by reference 
herein), and reducing agents, such as sodium thiosulfate or sodium 
bisulfite (see, e.g., Anderson et al., U.S. Pat. No. 4,421,664). Also, in 
conjunction with the litter, superabsorbent polymers, whether, used as box 
liners, cut into discrete pieces, or formed into particles, can be 
utilized, such as suggested in Arnold, U.S. Pat. No. 4,494,482, Insley, 
U.S. Pat. No. 4,650,479, and Yanaton, U.S. Pat. Nos. 4,469,046 and 
4,640,225. Further, fragrances, which are used to mask odors can be used. 
The fragrances can be uncoated (e.g., fragrance blends) or encapsulated 
(as in Colborn et al., U.S. Pat. No. 4,407,231). Further adjuncts include 
dedusting compounds or agents, such as water-soluble polymeric resins, 
e.g., polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, xanthan 
gum, gum arabic, other natural resins, and mixtures of any of these 
resins. 
In the EXPERIMENTAL section which follows, Applicants further demonstrate 
the surprising and dramatic results which are obtained when pine oil is 
added as an odor controlling agent to animal litters.