Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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NON-DUSTING, ODOR CONTROL AND CLUMPING SODIUM BENTONITE/CALCIUM
CARBONATE-BASED COST EFFECTIVE ANIMAL LITTER
FIELD OF THE INVENTION
The disclosure of this invention generally relates to a dust and odor control
particular
materiai and a process for making the same. The disclosure more particularly
relates to
disposable cat litter and a method of making the same. In one embodiment, this
invention is directed to a process (FIG. 6) and a cat litter composition
formed primarily
from sodium bentonite and calcium carbonate in particulate form where the
blend
particles are treated, e.g. surface treated, first with preferably vegetable
or synthetic oil
and secondly with an inhibiting odor agent based on polyborate and a method of
making
the same. After treatment, the cost effective cat litter is dust-free and
furthermore has
significantly increased odor control properties.
BACKGROUND
Animal litters
Animal and pet litters, such as cat litters, are typically mixtures of
absorbent materials,
odor controlling agents, clumping agents, and other functional or cosmetic
enhancing
additives. Absorbent materials cover a wide range of materials and can include
recycled
newsprint, paper sludge, corn cob granules, rice hulls, peanut hulls, alfalfa,
cedar
sawdust, and various clays such as calcium and sodium montmorillonites
(including
sodium bentonite), attapulgites, kaolins, and opal clay mixtures. Currently,
clay-based
litters which provide a clumping property allowing removal of liquid waste
from the litter
container without excessively contaminating the remaining litter have become
popular.
Clumps are created when the composition of the swells during the absorption of
pet
urine, creating a localized rigid clump. Typical additives for litter which
provide this
swelling and urine absorption property include montmorillonite clays.
Clay particles have long been used for providing small animals with dry,
sanitary,
dustless and relatively odorless litter and bedding. The clay-based litters
are now widely
used. However, the quality of the cat litters on the market wopuld benefit
from
improvement; they are often dusty, develop urine odors and attach to the
animal's fur or
paw and will be tracked throughout the house. The dry clay in the house may
become a
source of dust that may carry microorganisms and/or cause allergic reactions.
Also,
when the animal licks its paws, the clay will be ingested by the animal and
may cause
the animal health problems.
The animal litter nevertheless is dusty during manufacture, as well as
dispensing.
What is needed is a relatively dust-free clumping animal litter that can be
periodically
disposed. Also needed is a cat or animal litter composition that retards the
formation of
odiferous substances and eliminates the malaise odor of common litter boxes.
Odor control is generally achieved by adding ingredients to the litter that
either mask the
odor or add compounds that are anti-bacterial, or other compounds that exhibit
pleasant
smell. The uririe odor is created by the formation of amine containing
compounds
produced by decomposition of urine and by urine decomposing gram-positive
bacteria.
Many approaches have been tried to produce a litter that is humane and animal
safe and
acceptable.
U.S. Pat. No. 5,329,880 to Pattengill, et al. discloses clumpable animal
litter. This
waterproof litter contains a mixture of non-smectitic, hydrophilic shale
aggregate with a
fraction of coarse material with a size less than about 5 mesh (4000 microns).
The
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mixture has the property of agglomerating into a clump upon contact with
urine. The
agglomerated clump of shale and urine is removable with a perforated scoop.
The shale
may contain up to 10 weight percent clumping agent selected from the group of
water
absorbent polymers, corn starch, gelatin, gluten and dried plants of the
Plantago family.
In addition 5 to 25 wt % ammonia absorbing zeolite may be added for odor
control. The
odor control agent is an absorbent for ammonia and does not provide odor
control since
ammonia is not immediately formed.
U.S, Pat. No. 5,806,462 to Parr discloses clumping animal litter. The animal
litter is
particularly for cats and has a gelatin solution and a dry adhesive sprayed
onto the
granules. The gelatin solution provides enough dampening to adhere the
adhesive
particles to the clay particles. Because the gelatin sets quickly, it does not
provide so
much wetting as to activate the adhesive. Therefore, the adhesive retains its
adhesive
properties ancl, together with the gelatin, causes the litter to clump when
wetted by an
animal. This clumping cat litter formulation provides no odor control.
U.S. Pat. No. 3,675,625 to Miller et al. teaches 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.
U.S. Pat. No. 4,129,094 to Stockel discloses the use of fly ash, bottom ash
and/or boiler
slag as cat litter materials. The composition of fly ash, as determined by the
ASTM
includes silicon dioxide, alumina, ferric oxide, calcium oxide, magnesium
oxide, sodium
oxide and potassium oxide. This is a complex chemically reacted composition
and
absorbs urine but does not eliminate the odor.
U.S. Pat. No. 4,203,388 to Cortigene et al. teaches the use of a deodorant
such as
sodium bicarbonate, in amounts of between about 1% and about 10% of the dry
weight
of the litter. Such large amounts of deodorizer are necessitated since the
litter itself is
also used as an absorbent for urine, requiring the deodorizer to be
homogeneously
dispersed throughout the particles of the litter.
U.S. Pat. No. 4,405,354 to Thomas et al. discloses the use of buffering agents
to prevent
gaseous ammonia from escaping into the air. However, such buffering agents
serve only
to prevent the formation of gaseous ammonia; they are ineffective against
other
unpleasant odors. Further, the amounts of such agents range from about 0.5% to
about
25% by weight, since all of the absorbent litter must be treated with the
agent to provide
sufficient contact with the urine.
U.S. Pat. No. 4,494,482 to Arnold discloses an animal litter composition. This
solid
absorbent material has about 25 ppm to about 500 ppm of a halogenated aromatic
hydrocarbon bacteriostat that effectively prevents the development of urine
odors. The
bacteriostat is selected from the group consisting of p-chloro-m-cresol;
hexachlorophane, 2,4,4'-trichloro-2'-hydroxydiphenyi ether,
trichlorocarbanilide, 2,4-
dichloro-m-xylenol, 3,4,5-tribromosalicylanilide, 3,5,3',4'-
tetrachlorosalicylanilide or
3,5,3',5'-tetrachlorodiphenyl sulfide. These chlorinated or brominated
compounds kill
odor-producing bacteria.
U.S. Pat. No. 5,097,799 discloses odor control agents selected from the group
consisting
of guanidine salts, alkali metal fluorides, alkali metal bisulfites, and
mixtures thereof.
These agents are applied to the litter using an aqueous dispersion to produce
an odor
control animal litter.
U.S. Pat. No. 5,634,431 to Reddy, et al. discloses odor inhibiting pet litter.
The addition
of urease negative bacteria to sodium srnectite clay minerals in pet litter
inhibits growth
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of urease positive bacteria for a period of several days, thereby retarding
formation of
ammonia and other obnoxious odors. Approximately fifty percent sodium
bentonite in the
litter causes the litter to clump upon wetting, maintaining the urea in
contact with the
treated clay and also serving as a buffer to favor growth of the urease
negative bacteria.
This composition entirely relies on inhibiting ammonia formation and does not
provide
immediately a pleasant scent.
U.S. Pat. No. 5,975,019 to Goss, et al. discloses clumping animal litter. The
clumping
animal litter utilizes tiie interparticle interaction of sodium bentonite
swelling clay with a
non-swelling clay material. Preferably, sixty percent (60%) by weight, or
less,
composition of sodium bentonite is used after the judicious selection of
particle size
distribution such that the mean particle size of the non-swelling clay
material is greater
than the mean particle size of the sodium bentonite. In addition, an organic
clumping
agent, such as a pregelatinized corn starch can be combined with the sodium
bentonite/clay mixture to enhance clumping properties. This clumping clay
litter does not
control odor.
U.S. Pat. No. 6,015,550 to Marquis discloses a method for controlling odor
using
alkylene carbonates. These alkylene carbonates are useful for reducing odor
where an
odoriferous amine-containing compound is present under conditions such that
the
alkylene carbonate forms a reaction product with odoriferous amine-containing
compounds reducing the odor. Sources of such amine-containing compounds
include
chicken coops, dumps, landfills, cat litter, stagnant water, water treatment
ponds and
plants, garbage cans and dumpsters, dog kennels, zoos, rendering plants food
processing plants, slaughter houses, wool plants, fish canneries (cleaning and
processing plants), underground sewers, paper mills, paper processing,
outhouses and
toilets that have no running water, and public restrooms. The alkylene
carbonate is
ethylene carbonate, propylene carbonate, butylene carbonate. Propylene
carbonate is a
liquid at room temperature and has to be sprayed. Ethylene carbonate is a
solid at room
temperature and does not immediately react with the odor molecules. Therefore,
it is
unsuited for incorporation in a cat litter.
U.S. Pat. No. 6,206,947 to Evans, et al. discloses a process for making an
animal litter
comprising gypsum, aluminum sulfate and urea. The animal litter composition is
an
agglomerated or compacted calcined calcium sulfate absorbent. The animal
litter
composition is screened to a particle size between 6 mesh and about 100 mesh
and an
effective amount of a binder such as a clay, lignin or starch is added to the
calcium
sulfate to assist the calcium sulfate to pelletize. This is a gypsum
composition that is
agglomerated using aluminum sulfate and urea to chemically combine with
gypsum.
There is no odor control in this clumping litter composition.
U.S. Pat. No. 6,253,710 to Ward, et al. discloses odor control for animal
litter. It uses an
odor control liquid and an aerosolized coniposition for deodorizing and
controlling the
odor of animal wastes. The liquid and aerosolized composition comprises a non-
aqueous volatile carrier and an odor control agent. The liquid and aerosolized
composition can be applied in liquid form directly to the animal litter and/or
the animal
container and/or the animal waste. The litter container may be sprayed with a
powdered
release agent which may be talc, inorganic silicone and magnesium powders,
sodium
bicarbonate, chlorophyll, sodium dihydrogen phosphate, potassium acid
phthalates, or
their mixtures preventing the stickiness of the odor controlling liquid. The
liquid mixes
with the litter product and always evaporating disseminates the odor control
agent and is
quickly exhausted.
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U.S. Pat. Nos. 6,667,030 and 6,743,420 to Schneider disclose odor control
composition
and process. The odor control composition eliminates household, institutional
and
industrial odors including cat urine odor. The odor control composition is a
solution of
Chloramine-T which may incorporate a suitable wetting agent. Chloramine-T
describes a
variety of compounds which are based on N-Sodium, N-chloro-para-
toluenesulfonamide
and N-Sodium, and N-Chloro-Para-Benzene sulfonamide. This chlorine-containing
compound is highly reactive and is unsuitable for use in a cat litter.
U.S. Pat. No. 6,702,951 to Shultz discloses scent adsorbing liquid
formulation. This
odor-absorbing liquid formulation comprises a preservative an alkali metal
salt, and a
particulate odor-adsorbing agent such as activated carbon. The fqrmulation may
further
include an alkylaryl polyether nonionic surfactant and may lrave an alkaline
pH. The
liquid formulation is applied to apparel to be worn during hunting or
observation to avoid
being sensed by animals and is not included in cat litter. The alkaline pH may
be
advantageous in promoting penetration or coverage of the substance being
treated, in
retarding formation of some odiferous substances, and in providing an
environment in
which the anti-microbial preservatives are most effective in inhibiting
bacterial growth
and development.
U.S. Pat. No. US 20030072733 discloses a free flowing, fragranced, moisture
absorbing,
composition of an enrobement material such as clays, silicas, celites,
zeolites, metal
salts, celluloses, starches, carbonates, borates, sulfates, water soluble
polymers, borax,
and mixtures thereof, a fragrance, an absorbent material, and a fixative.
Borate, boric acid and polyborates
Boric acid and sodium tetraborate have been used for years as an insecticide,
fungicide,
herbicide, and bacteriocide, but are virtually non-toxic to humans, animals,
birds, fish,
aquatic invertebrates, beneficial insects and have a low impact on the
environment. The
LD50 toxicity of borax is about the same as table salt (e.g. 3,000 mg/kg body
weight).
Boron, as found in boric acid and sodium tetraborate, is an effective specific
inhibitor of
bacterial urease and hydrogenase. One of the key reactions involved in the
release of
ammonia from urine in cat litter is the hydrolysis of urea by the bacterial
enzyme, urease.
Many enteric bacteria possess urease activity, including pathogens such as
Escherichia
coli, Actinobacillus pleuropneumoniae, Salmonella, Klebsiella, Clostridium,
Streptococcus and Staphylococcus.
Boric acid and sodium tetraborate were evaluated for their ability to inhibit
ammonia and
hydrogen sulfide emissions from swine wastewater and manure slurry in in-vitro
incubations. Addition of either 1% boric acid or sodium tetraborate inhibited
ammonia
and hydrogen sulfide emissions by almost 100 % froni wastewater and manure
slurries
over 7 days of incubation. Concentrations of boric acid and sodium tetraborate
as low as
0.0625 %, were effective in treating wastewater. Other possible benefits for
using boron
include a reduction in malodor of the manure slurry, control of enteric
pathogens and
inhibition of mold growth.
Products based on borax are thought to involve the borate inhibition of the
urease
enzyme, preventing ammonia formation. Isao Tsuyumoto et al. in Inorganic
Chemistry Communications 10 (2007) 20-22, reported that borates are used
extensively in treating wood to protect against decay by brown and white rot,
and
staining by fungi. Insecticidal use of borates is attractive because of their
low mammalian
toxicity and lack of insect resistance compared with the organic insecticides.
The
literature contains over 150 references in this field. Species showing promise
for control
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by borate-based insecticides are the powder post beetle (Lyctus brunneus) in
hardwoods and larvae of several other beetles which attack soft wood. Some
species of
subterranean termites like Coptotermes and Reticulitermes which contain gut
protozoa
are susceptible, because boron is toxic to these cellulose-digesting organisms
and leads
5 to starvation of the host as well as systemic effects. Less research has
been done on
drywood termites, but some success has been obtained with Cryptotermes.
Sodiuni
octaborate, a highly soluble polyborate, is of interest both for pre and
posttreatment of
wood.
U.S. Pat. No. 5,183,655 teaches an odor control animal litter that has applied
to it an
effective amount of pine oil in combination with an effective amount of boric
acid.
U.S. Pat. No. 5,992,351 to Jenkins discloses clumpable animal litter with
improved odor
control. The clumpable animal litter with improved odor control comprises a)
water-
swellable clay particles capable of adhering other such particles upon contact
with
moisture; and b) an odor controlling-effective amount of a boron compound of a
composition di-alkali metal tetraborate n-hydrate, wherein n is 4, 5 or 10,
which controls
odors arising from the contact of said clay particles with moisture.
U.S. Pat. No. 4,949,672, Jenkins; Dennis B. et al. teaches an odor control
animal litter
comprising particles of an absorbent clay substrate. The particles have being
contacted
with a liquid carrier containing an odor-controlling-effective amount of a
mixture of boric
acid and borax having an equivalent boron level of at least 0.06% and said
liquid carrier
comprising an alkali metal hydroxide in solution.
Still further, it has been suggested in U.S. Pat. No. 4,263,873 to
Christianson, that a
borax/boric acid mixture at a pH of 4-4.5 could be added to a cellulose litter
containing a
pheromone. Yet further, in U.S. Pat. No. 5,094,190 to Ratcliff et al. teaches
an odor
control animal litter to which a boron-containing liquid material has been
applied. Ratcliff
et al. 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.
This reference has several deficiencies in that when borax and boric acid are
mixed
together with sodium hydroxide in solution before spraying the cat litter
yielded
metaborate tetrahydrate as precipitating product which blocks the nozzles of
spraying
machine and decrease the concentration of borate needed to react with odor
generating
material. When we prepare a saturated solution at high temperature by
dissolving boric
acid or borax into hot water and then cool it to a room temperature, the
solution
recrystallizes and becomes a saturated solution at room temperature. Large
amounts of
boron are necessitated since the litter itself contains particles of solid
metaborate that
have been precipitating from the saturated solution during the spraying
processes.
Consequently, the odor control agent is not homogeneously dispersed throughout
the
particles of the litter and the critical level of at least 0.06% equivalent
boron is needed.
It is well known that in order to increase the solubility of borax, many
researchers add
sodium hydroxide to the aqueous borax solution. However, the mixture of borax
and
sodium hydroxide led to the formation of metaborate tetrahydrate, NaB(OH)4 -
2H20, and
this substance became to be commonly denoted by NaBO2 - 4H20.
As example, when 0.692g borax and 0.145g sodium hydroxide are dissolved in
water,
these two make 1.0g sodium metaborate tetrahydrate which precipitate in
solution
according to the following reaction.
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Na 21340 7+ 2NaOH -> 4NaB0 2+ 2H 20
Moreover, Boron is adsorbed predominantly on clay minerals, iron and aluminium
oxides
and organic rnatter. Maximal adsorption occurs mostly in the alkaline range
from pH 8 to
10, and decreases sharply to practically negligible amounts under acidic pH
conditions
as reported by Goldberg & Glaubig 1.91185, 10RFn, 1 g~ah 10P8, uoron Q. Rin
h~n,
IvVV(w VVN, VV 1\l.llJll l,Jl lJlllgllUlll,
1985). Goldberg, S. & Glaubig, R. A. (1985) Boron adsorption on aluminum and
iron
oxide minerals. Soil Sci. Soc. Am. J. 49, 1374-1379. Goldberg, S. & Glaubig,
R. A.
(1986a) Boron adsorption on California soils. Soil Sci. Soc. Am. J_ 50, 1173-
1176.
Goldberg, S. & Glaubig, R. A. (1986b) Boron adsorption and silicone release by
the clay
minerals kaolinite, montmorillonite, and illite. Soil Sci. Soc. Am. J. 50,
1442-1448.
Goldberg, S. & Glaubig, R. A. (1988) Boron and silicon adsorption on an
aluminum
oxide. Soil Sci. Soc. Am. J. 52, 87-91.
Different kinds of boron adsorption mechanisms are known from the literature.
The pH
dependency of boron adsorption in terms of the percentage of boron present in
ionic
form (referenced to total boron) was described, the ionic form being adsorbed
more
readily than the uncharged form. In water, boric acid forms an ion by the
addition of OH-
to form the hydroxyborate ion B(OHY4. The first hydrolysis constant is Ki =
5.8-10-10 or
9.28 expressed as pK (at 20 C). Polyborate ions occur at higher boron
concentrations,
predominantly at high pH-values. The equilibrium between boric acid,
monoborate ions
and polyborate ions in aqueous solutions are rapidly reversible.
Because of the various differences of the above products, there currently
exists a need
for an animal or cat litter which is dust free, odorless (and thus natural
smelling to the
animal user) and trackless.
SUMMARY OF THE INVENTION
The present invention responds to the above-mentioned need by providing a dust
and
odor control particulate material, a process of making the same and a use of
an aqueous
solution of polyborate ions.
In one embodiment, the invention provides the use of a synthetic or vegetable
oil
sprayed onto animal litter in order to make a hydrophobic film on the surface
of the
swelling clay composition as a temporary water barrier film. Boron ions are
adsorbed by
clay minerals, thus explaining why the soil is enriched with respect to boron.
The clay's
treatment with oil eliminates the dust and helps the odor control aqueous
solution
sprayed onto animal litter to be available on the surface of clay and not to
be completely
absorbed inside the clay particles. This process was efficient in controlling
dust and urine
odor. The critical level of aerosolized odor control composition is only 0.01%
equivalent
boron which is 6 times less than the critical level reported by Ratcliff et
al. Particulate
substrate to which has been applied a liquid carrier containing a boron-
containing
material extends the life of litter with a good odor control to one month with
no urine
smell. This drastic increase in the borate concentration effect at low
critical level is due to
formation of the polyborate ions containing more boron atoms. Furthermore,
none of the
prior art has taught the combination of an odor control agent based on
polyborate ions in
combination with an organic solution, to provide long-term dust and odor
control for
animal litters.
In one embodiment, the invention provides a process for controlling dust and
urine odors
in cat litter. Perfumed odor control compositions have been used for thousands
of years
however these solutions did not destroy the odorous materials but instead they
only
masked the odors caused by the odorous materials. In contrast to this masking
of the
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troublesome odorous material in the prior art, the compositions of this
invention react
with the odorous molecules. In the prior art odor control compositions, are
perfumes
wtierein the odors are masked with a synthetic or natural essence. In the
subject
invention, instead of masking the odor with a perfume, the odor causing
molecules are
degraded by reaction with a very low concentration of polyborate ions. The use
of borate
is known in odor control and boron, as commercial borax, is an economical
treatment,
costing less than $2 per kg. The preferred sources of the borate moiety for
use in
accordance with this invention are Boric acid and Borax.
Most odor causing molecules are mercaptans, sulfides or amine based compounds,
or
other sulfur or nitrogen compounds. Polyborate ions are excellent agents for
eliminating
odors which are amine based. In one embodiment, this invention relates to the
utilization of polyborate anions solution prepared from a critical ratio of
Boric acid and
Borax salt in aqueous solution, which react with odor producing molecules as
may be
contained in animal litters. The performance of the odor control compositions
in
accordance with this invention is further enhanced by the presence of small
percentages
of a dust-controlling agent onto the surface of the clay particles.
The present invention relates to novel process and additives for animal
litter, in the
eradication of malodor in the cat litters. More specifically, this invention
is directed to a
cat litter composition fornied principally from sodium bentonite and calcium
carbonate in
particulate form where the blend particles are treated, e.g. surface treated,
with
preferably aqueous solution of polyborate ions sprayed onto cat litters, thus
inhibiting
growth of urease positive bacteria for a period of several weeks, thereby
retarding
formation of ammonia. The composition of cat litter material is used after the
well judged
selection of particle size distribution such that the mean particle size of
the non-swelling
material is equal or greater than the mean particle size of the sodium
bentonite.
The solubilities of boric acid and borax in water are not sufficiently high at
room
temperature, and thus there are technical difficulties in impregnating
sufficient amount of
the active constituent into cat litter. However, their solubilities in hot
water are rather high
but when the temperature decreases this causes the precipitation of crystals
on surfaces
of cat litter and results in some technical problems in the coating process.
In order to
establish effective odor control of cat litter, a highly concentrated aqueous
solution of
borate at room temperature is wanted. These concentrated sodium borate
solutions are
useful as odor controlling agents because of a remarkable inhibiting urine
effect for clay-
based materials such as sodium bentonite.
In the present invention, we have successfully prepared a highly concentrated
aqueous
solution of sodium borate.
However, when the mixture of boric acid and borax was dissolved at a certain
ratio in hot
water as reported by lsao Tsuyumoto et al. in Inorganic Chemistry
Communications 10
(2007) 20-22. The solution did not show recrystallization after cooling to
room
temperature. This was not oversaturation because the solutions remained
transparent
without any precipitation. lsao Tsuyumoto et al. suggested using the Raman
spectroscopy and the APCI/MS (atmospheric pressure chemical ionization/mass
spectrometry) analysis the formation of polyborate ions such as B,o 012 (OH)82-
at a
highly concentrated aqueous solution of sodium borate.
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8
To our knowledge, boric acid and sodium tetraborate dissolved at high
concentration in
water have not been studied to control ammonia according to the process and
preparation method reported in this invention.
According to one aspect of the invention, there is provided a process for
making a dust
and odor control particulate material, comprising : applying a dust control
organic
solution comprising vegetable, mineral or synthetic oil to substrate particles
so as to form
a water barrier film that is substantially unreactive to polyborate ions;
preparing an odor
control aqueous solution comprising polyborate ions by mixing boric acid and
borax in a
ratio between about 0.825 and about 0.71; applying the odor control aqueous
solution to
the water barrier film so as to form an odor control layer at the surface of
the substrate
particles.
Optionally, the boric acid and borax ratio is about 0.79.
Optionally, the dust control organic solution is applied by spraying.
Optionally, after spraying the dust control organic solution, drying and
blending the
resulting particulate material before applying the odor control aqueous
solution.
Optionally, the preparing of the odor control aqueous solution comprises
heating an
aqueous solution, adding the borax and the boric acid to form a highly
concentrated
solution and then cooling ttie highly concentrated solution without
substantial
precipitation of crystals.
Optionally, the dust control water barrier film is present in a concentration
between about
0.2 wt% and about 3 wt% of the particulate material and has a thickness
between about
15 and bout 250 microns.
Optionally, the concentration of boron in the odor control aqueous solution is
above 2.5
rnol/kg, preferably above 3 mol/kg, still preferably above 3.25 mol/mg.
Optionally, the substrate particles comprise clay.
Optionally, the substrate particles comprise sodium bentonite.
Optionally, the sodium bentonite is present in a concentration between about
80 wt% to
about 95 wt% of the particulate material.
Optionally, the clay is a clumping clay.
Optionally, the boron is present in a concentration between about 0.005 wt >o
and about
0.05 wt% with respect to the particulate material.
Optionally, the odor control layer is present in a concentration between about
0.01 wt%
and about 0.03 wt% of the particulate material.
Optionally, the substrate particles comprise calcium carbonate.
Optionally, the calcium carbonate is present in a concentration between about
3 wt%
and about 20 wt% with respect to the particulate material.
Optionally, the dust control organic solution is anionic or non-ionic.
Optionally, the odor control aqueous solution has a pH of between about 8 and
about 5.
Optionally, the odor control aqueous solution has a pH of between about 7.5
and about
6.5.
Optionally, the particulate material has a particle size distribution between
about 8 mesh
and about 100 mesh.
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Optionally, the polyborate ions are available to react and inhibit bacterial
urease and
hydrogenase and the particulate material is an animal litter.
According to one aspect of the invention, there is provided a dust and odor
control
particulate rnaterial comprising: substrate particles;-a dust control water
barrier film on
the substrate particles formed from an organic solution comprising vegetable
or synthetic
oil, the water barrier film being substantially unreactive to polyborate ions;
an odor
control layer formed from an aqueous solution comprising polyborate ions from
boric
acid and borax in a ratio between about 0.825 and about 0.71, the odor control
layer
being applied on the water barrier film to remain at the surface of the
substrate particles.
Optionally, the boric acid and borax ratio is about 0.79.
Optionally, the dust control water barrier film is present in a concentration
between about
0.2 wt% and about 3 wt% of the particulate material and has a thickness
between about
and bout 250 microns.
Optionally,the concentration of boron in the odor control aqueous solution is
above 2.5
15 mol/kg, preferably above 3 mol/kg, still preferably above 3.25 mol/mg.
Optionally, the substrate particles comprise clay.
Optionally, the substrate particles comprise sodium bentonite.
Optionally, the sodium bentonite is present in a concentration between about
80 wt% to
about 95 wt% of the particulate material.
Optionally, the clay is a clumping clay.
Optionally, the boron is present in a concentration between about 0.005 wt%
and about
0.05 wt% with respect to the particulate material.
Optionally, the odor control layer is present in a concentration between about
0.01 wt%
and about 0.03 wt% of the particulate material.
Optionally, the the substrate particles comprise calcium carbonate.
Optionally, the the calcium carbonate is present in a concentration between
about 3 wt%
and about 20 v/t% with respect to the particulate material.
Optionally, the dust control organic solution is anionic or non-ionic.
Optionally, the odor control aqueous solution has a pH of between about 8 and
about 5.
Optionally, the odor control aqueous solution has a pH of between about 7.5
and about
6.5.
Optionally, the water barrier film is dried-on.
Optionally, the material has a particle size distribution between about 8 mesh
and about
100 mesh.
Optionally, the polyborate ions are available to react and inhibit bacterial
urease and
hydrogenase and the particulate material is an animal litter.
According to another aspect of the invention, there is provided a use of an
aqueous
solution comprising polyborate ions from boric acid and borax in a ratio
between about
0.825 and aboL.it 0.71 as an odor control layer on the surface of a
particulate material.
Optionally, the boric acid and borax ratio is about 0.79.
Optionally, the particulate material further comprises a dust control water
barrier film
CA 02688496 2009-12-14
onto which the odor control layer is applied, the water barrier film
comprising vegetable
or synthetic oil.
Optionally, the dust control water barrier film is present in a concentration
between about
0.2 wt% and about 3 wt% of the particulate material and has a thickness
between about
5 15 and bout 250 microns.
Optionally, the substrate particles comprise clay.
Optionally, the substrate particles comprise sodium bentonite.
Optionally, the sodium bentonite is present in a concentration between about
80 wt% to
about 95 wt% of the particulate material.
10 Optionally, the clay is a clumping clay.
Optionally, the the boron is present in a concentration between about 0.005
wt% and
about 0.05 wt% with respect to the particulate material.
Optionally, the odor control layer is present in a concentration between about
0.01 wt%
and about 0.03 wt% of the particulate material.
Optionally, the substrate particles comprise calcium carbonate.
Optionally, the calcium carbonate is present in a concentration between about
3 wt%
and about 20 wt% with respect to the particulate material.
Optionally, the particulate material has a particle size distribution between
about 8 mesh
and about 100 mesh.
Optionally, the particulate material is animal litter and the polyborate ions
are used to
inhibit bacterial urease and hydrogenase to control odors.
The optional aspects of the material, process and use mentioned here-above may
be
combined with various other optional aspects of the material, process and use
mentioned here-above.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood and further advantages will become
apparent
when reference had to the following detailed description of the preferred
embodiments of
the invention and the accompanying drawing, in which:
FIG. 1 is a chemical structure of Boric acid H3BO3
OH
I
Ho~ oH
FIG. 2: Chemical structure of sodium metaborate (non-hydrated)
CA 02688496 2009-12-14
11
00
I
o8\O
I I 3 N a~
O0 / BOB\O0
Molecular formula: Na3B3O6, 12H20, Molecular weight: 413.58, Description:
White solid,
odorless, Density: 1.90 g/mL at 25 C.
FIG. 3 is a chemical structure of H3B306
O--`B0
~~ p- OH
B OH
I
OH
Hydrated metaborate
FIG. 4 is a chemical structure of tetraborate H2B407
OH
O /
OH
O
B O--- B
B 0
FIG. 5 is a chemical structure of a polyborate: B,o 012 (OF06
OH
I
B
O \
j FI
O
O\ 0 B O~ B
B OH
\ ~ O B O B O
oH
B OH
O B
0B
OH \ B \
0/
FIG. 6 is a diagrammatic representation of the process of manufacturing
dustless and
CA 02688496 2009-12-14
12
odor control clay composition for use as cat litter.
Raw Materials
ctor
Wal-ellouse jtcoiieJ
scep i
Oc=gatni:,
solution
Bullc Production i Miaing Cliamber
Arueous
solution
t
step 2
PaCl:aging LDust joJIccto-
Shipping J
DETAILLED DESCRIPTION OF PREFERRED EMBODIMENTS
This invention is concerned witi ~ dust and odor control technology and more
particularly
the composition contains 80% to 95% by weight sodium bentonite, 5% to 20% by
weight
calcium carbonate, 0.2% to 3% by weight dust control agent and 0.01% to 0.03%
by
weight odor control agent. The animal litter composition is screened to a
particle size
between 8 mesh and about 100 mesh. To maintain the high quality of cat litter
materials,
we use different amounts (from 0% to 15%) of calcium carbonate depending on
the
physicochemical properties wanted. In order to provide cat litters that
possess better
absorption, diffusion and clurnping properties, we control the ratio
(bentonite/calcium
carbonate).
In accordance with this invention, odors attributed to cat litters can be
coritrolled or
eliminated. The odor control process of this invention comprises the
application of an
aqueous solution of the odor control composition of this invention, to an odor
containina
substrates, coated with a dust-controlling agent.
It was endeavored to determine if boric acid and sodium tetraborate are
effective in
controlling ammonia from used cat litters. Sonie specific objectives were:
(1) Deterniine the minimum effective concentration of organic solution -
synthetic or
vegetable oil- needed to eliminate dust and coat the surface of particles in
order to form
a temporary water barrier.
CA 02688496 2009-12-14
13
(2) Determine the minimum effective concentration of polyborate anions
obtained from
boric acid and tetraborate sodium in aqueous solution at 80 C to inhibit
ammonia
emissions in used cat litters.
(3) Deterniine the using time of cat litter where the dust and odor
controlling agents were
efficient.
Various embodiments of the invention provide the following characteristics and
advantages:
- A process for controlling dust and odor on a substrate which comprises the
steps of:
a) Applying an organic solution of vegetable or synthetic oil at an effective
amount of
dust control to the substrate wherein the solution essentially does not react
with
polyborate ions and,
b) spraying an aqueous solution containing an effective amount of polyborate
ions
prepared from Borax and Boric acid according to the critical ratio of (Boric
acid/Borax =
0.79).
- A dust coritrol additive produce by the above process, wherein the barrier
coating
has a thickness of about 15 to 250 microns.
- A process for manufacturing a dust and odor controlling cat litters as
recited above,
wherein the barrier coating comprises a first coating of said substrates with
dust-control
agent, followed by an odor-control agent composition coating. The
concentration of the
Boron may be from about 0.005 to about 0.05 weight percent; the concentration
of
sodium bentoriite niay be from about 80 to about 100 weight percent; the
concentration
of calcium carbonate may be from about 3 to about 20 weight percent; the dust
controlling agent may be an anionic or nonionic organic liquid; the odor
controlling agent
may be an anionic or nonionic aqueous solution based on polyborate ions; and
the odor
controlling agent in an aqueous solution may have a pH of 7.4.
VVhile the invention will be described in conjunction with example
embodiments, it will be
understood that it is not intended to limit the scope of the invention to such
embodiments. On the contrary, it is intended to cover all alternatives,
modifications and
equivalents as rriay be included as defined by the present description and
appended
claims.
Example:
Clumping cat litter product is made from high quality absorbent clay. Sodium
Bentonite
clay is a naturally-occurring and is a naturally swelling clay known for its
absorbent
qualities (1g of sodium bentonite can absorb up to 8g of distilled water).
Sodium
bentonite is composed of a combination of aluminum silicates and minerals.
A dust-controlling agent is added to the ground clay to prevent the dust,
created when
particles rub against one another, from becoming airborne. During the
production
process, the polyborate anions used as anti-bacterial agent were added to
prevent
odors.
Sample preparation
Samples of raw material acquired from the suppliers were used with no further
purification. 28 kg of experimental batches were produced using a small mixer,
where all
products needed were added simultaneously. Mixing lasted 3 to 5 minutes in
each case,
after which, a 10 kg sample was transferred into a bucket for future testing.
CA 02688496 2009-12-14
14
Testing
The tests were completed according to the procedures in the test methods
supplied by
INTERSAND. The results were compared to the predetermined standards.
Materials and Methods:
1- Raw Materials:
Sodium Bentonite,
Calcium Carbonate,
Dust-controlling agent (oil),
Anti-bacterial agent (Aqueous salts solution).
The pH of sodiuni bentonite is 10.00.
Sodium bentonite size distribution:
Sieve size Percentage Standards
7 0
8 0
12 0,1 0.5 max
25 81,9 80 min
40 16,8
100 0,8 1 max
bac 0,13 0.2 max
Sodium bentonite Dust (ppm):
Dust Level
Sample (PPM)
1 15.5
14.7
3 16.3
Average 15.5
Moisture Content of sodium bentonite:
Sodium Bentonite %
Standards
(target/max) 8 / 10
Average 8,90
Std. Dev. 0,58
min 7
max 10
CA 02688496 2009-12-14
Bulk Density of sodium bentonite:
Total average density: 0.974 g/ml
59.233 Ibs/ft3
Water absorption of sodiurri bentonite, Free Swelling Capacity (FSC):
FSC (%) ASTM
method
698
639
603
600
546
693
562
596
Average 617
standards 500 rnin
Calcium Carbonate or Limestone size distribution:
Sieve size Average (%) Standards
7 0,00
8 0,00
12 0,00 0.5 max
65,13 67 max
40 33,97 36 max
100 0,83 1 max
Bac 0,10 0.1 max
Limestone Dust (ppm):
Dust Level
Sample (ppm)
1 25.7
2 28.3
3 26.1
Average 26.7
5 Moisture Content of Limestone:
CA 02688496 2009-12-14
16
limestone %
standards
(target/niax) 0.2 / 1.0
Average 0,24
Std. Dev. 0,06
Bulk Density of Limestone:
Target 84; min 81,5; max
86,5 Ibs/ ft3
Average Density
Sample Total mass (g) Mass (g) Density (g/ml) (g/ml)
1 565,3 367,1 1,343
2 565,1 366,9 1,342
1,341
3 563,7 365,5 1,337
4 563,2 365 1,336
81,540 lbs/ft3
Boric acid and sodium tetraborate were commercial grades. Boric acid H3BO3,
has F.W.
61.83 and sodium tetraborate (Na2B4O7, 10H20) has F.W. 381.28.
Boric acid is a weak acid (Ka = 5.8 X 10-10), slightly soluble in water and
contains 17.5 %
boron. The solubility of boric acid in distilled water is 5,04 g/100 ml at 20
C (Lange
reference), corresponding to 4.8%. The pH of aqueous boric acid solution
ranges from
6.1 at 0.16 g/L to 3.7 at 7.6 g/L. Sodium tetraborate decahydrate (borax) is
slightly
soluble in water and contains 11.35 % boron. The solubility of borax in
distilled water is
5,1 g/100 ml at 20 C (ISSP reference), corresponding to 4.9%. The pH of the
aqueous
borax solution is 9.2 and almost constant over a wide range of concentration.
Borax or Boric acid size distribution:
Sieve size Average (%)
On 8 0
On 100 90,5
Bulk Density of Borax or Boric acid:
Borax decahydrate Staridard
99,8% 99,8 % min
Preparation techniques
Organic solution - synthetic or vegetable oil- used herein in this example was
synthetic
oil P10T. This P10T oil was used as received.
Preparation of aqueous solution of odor controlling agent:
Dissolution of alkaline metallic borates in aqueous media is faster than the
others and
dissolution rate of borates in general is increased with increasing
temperature. Boric acid
CA 02688496 2009-12-14
17
and borax dissolve faster in hot waters than cool waters. The temperature used
to
dissolve borax and boric acid in this example is 80 C. The odor control
aqueous solution
of this invention containing active ingredients which will react with the odor
generating
material has pH = 7.4. The solutions of this invention are effective on
different kind of
clay over a pH range of 6-14.
The equilibriuni which occurs in various aqueous solutions of boric acid and
borate has
been extensively studied. From the results it is clear that, in addition to
the mononuclear
boric acid and orthoboric ion which have been well established by infrared and
Raman
spectroscopy to be trigonal B(OH)3 and B(OH)-4 species, a number of polyborate
ions
also are formed.
B(OH)3 + H20 -> B(OH).4 + H+
The aqueous chemistry of the borates is dependent on concentration and pH.
Dilute
aqueous boric acid solutions are comprised solely of B(OH)3 and B(OH)4
species.
2- Recipe No. 1 of Anti-bacterial agent:
83% Water,
9.3% Borax Decahydrate
7.4% Boric acid
A highly concentrated aqueous solution of sodium borate was prepared at 80 C
with pH
= 7.4. This is more than twice more concentrated than the most soluble known
borate.
The solution was prepared by dissolving 7.4 g of boric acid and 9.3 g of borax
into 83 g
of hot water over 70 C did not recrystallize at 20 C. Chemical structure
presented in
FIG. 5 for polyborate B,o 012 (OH)c, is considered to be the principal polymer
formed by
condensation of the conventional borate ions derived from boric acid and
borax. This
gives a ratio of moles of boron/kg or solution of 2.17.
Recipe No. 2 of Anti-bacterial agent:
75% Water
13.9 % Borax Decahydrate
11.1 % Boric acid
This gives a ratio of moles of boron/kg of solution of 3.26. This is well
above 2.5 moi/kg.
In theses conditions the pH is situated between 6,5 et 7.
3- Formula of cost effective cat litter from recipe No. 1:
85% Sodium Bentonite,
15% Calcium Carbonate,
1% Dust-controlling agent,
0.5% Anti-bacterial agent
Formula of cost effective cat litter from recipe No. 2:
0.334 % of the anti-bacterial agent
4- Manufacturing steps:
The production process of cat litter is based on clay and Calcium carbonate.
The raw
materials are used as received and mixing represents one of the key
manufacturing
steps for products. The dust-controlling and odor-controlling agents are in
the liquid form.
They are sprayed sequentially in the mixer onto the blended clay and calcium
carbonate.
The particulate substrate to which has been applied a dust-controlling agent
is dried and
blended for a period of time before to be treated with the odor-controlling
agent.
CA 02688496 2009-12-14
18
Cat litter Clumping (%):
Product Clumping (%)
88 target, 85
Standards min
Sample 1 88,5
Sample 2 87,4
Saniple 3 88,3
Cat litter Dust (ppm):
Dust Level
Sample (PPM)
1 0.704
2 0.645
3 0.567
4 0.571
0.563
6 0.593
7 0.714
8 0.686
9 0.633
0.686
Average 0.636
5
