U.S. patent application number 11/058147 was filed with the patent office on 2005-07-07 for animal litter.
Invention is credited to Fung, Kent K., Jenkins, Dennis B., Ping, Wendy L., Wheeler, Daniel E..
Application Number | 20050145186 11/058147 |
Document ID | / |
Family ID | 31494817 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050145186 |
Kind Code |
A1 |
Fung, Kent K. ; et
al. |
July 7, 2005 |
Animal litter
Abstract
An improved odor control animal litter composition comprising a
substantially particulate silica gel material with a particle size
distribution of about 0.15 to about 4 mm. In additional
embodiments, the litter composition also includes at least one of
the following components: fixing agent, colorant agent,
anti-bacterial agent, fragrance, odor controlling agent, and/or
supplemental absorbent materials.
Inventors: |
Fung, Kent K.; (Pleasanton,
CA) ; Jenkins, Dennis B.; (Pleasanton, CA) ;
Ping, Wendy L.; (Pleasanton, CA) ; Wheeler, Daniel
E.; (Pleasanton, CA) |
Correspondence
Address: |
Roger V. Lee
THE CLOROX COMPANY
P.O. BOX 24305
OAKLAND
CA
94623-1305
US
|
Family ID: |
31494817 |
Appl. No.: |
11/058147 |
Filed: |
February 14, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11058147 |
Feb 14, 2005 |
|
|
|
10215174 |
Aug 7, 2002 |
|
|
|
Current U.S.
Class: |
119/171 |
Current CPC
Class: |
A01K 1/0155 20130101;
A01K 1/0154 20130101 |
Class at
Publication: |
119/171 |
International
Class: |
A01K 001/015 |
Claims
What is claimed is:
1. An animal litter comprising: a substantially particulate silica
gel material with a particle size distribution between 0.15-2
mm.
2. The animal litter recited in claim 1, wherein at least 90% of
said silica gel material has a particle size ranging between 1-2
mm.
3. The animal litter recited in claim 1, wherein said silica gel
material has a mean particle size between 1-1.5 mm.
4. The animal litter recited in claim 1, wherein said silica gel
material is Type A, B, C, or macroporous silica gel.
5. The animal litter recited in claim 1, wherein said composition
includes a fixing agent.
6. The animal litter recited in claim 5, wherein said fixing agent
comprises less than 2%, by weight, of said litter composition.
7. The animal litter recited in claim 1, wherein said litter
composition includes a colorant agent.
8. The animal litter recited in claim 7, wherein said colorant
agent comprises up to 5% of said litter composition.
9. The animal litter recited in claim 7, wherein said colorant
agent is disposed on at least 10% of said silica gel material.
10. The litter composition of claim 7, wherein said colorant agent
comprises a dye selected from the group consisting of direct dyes,
vat dyes, sulfur dyes, acid dyes, mordant acid dyes, phthalocyanine
dyes, anthraquinone dyes, polymeric dyes, quinoline dyes, monoazo,
disazo and polyazo dyes.
11. The animal litter recited in claim 7, wherein said colorant
agent comprises a pigment.
12. The animal litter recited in claim 1, wherein said colorant
agent is disposed on said silica gel material in an amount
sufficient to substantially resist a color change in the b region
of the L.a.b color scale.
13. The animal litter recited in claim 1, wherein said colorant
agent is disposed on said silica gel material in an amount
sufficient to resist a color change in the b region of the L.a.b
color scale less than about 10 units.
14. The animal litter recited in claim 1, wherein said litter
composition includes an antibacterial agent.
15. The animal litter recited in claim 1, wherein said litter
composition includes at least one fragrance.
16. The animal litter recited in claim 15, wherein said fragrance
is substantially encapsulated.
17. The animal litter recited in claim 1, wherein said litter has a
hydraulic conductivity less than or equal to 0.25 cm/s as measured
by following ASTM method D2434-68 (2000).
18. The animal litter recited in claim 1, wherein said litter has a
weight percent dynamic absorption capacity of greater than
100%.
19. An animal litter comprising: a substantially particulate silica
gel material with a particle size distribution between 0.15-2 mm;
and up to 1% of a material selected from the group consisting of a
fixing agent, a colorant agent, an anti-bacterial agent, an odor
controlling agent, a fragrance and mixtures thereof.
20. An animal litter consisting essentially of: a substantially
particulate silica gel material with a particle size distribution
between 0.15-4 mm; and up to 5% of a material selected from the
group consisting of a fixing agent, a colorant agent, an
anti-bacterial agent, an odor controlling agent, a fragrance and
mixtures thereof.
Description
RELATED APPLICATION
[0001] This patent application is a continuation-in-part of U.S.
patent application Ser. No. 10/215,174, filed Aug. 7, 2002,
entitled Improved Animal Litter, inventors Roger V. Lee et al.,
which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to absorbent litters
for pets. More particularly, the present invention relates to a
silica gel based litter composition that efficiently absorbs urine
without permeation to the bottom of the litter container by means
of a well-defined particle size.
BACKGROUND OF THE INVENTION
[0003] Domestic, house-broken animals, particularly cats, are
typically trained to urinate and defecate in a specially provided
litter box. Consequently, pet owners, homeowners, veterinarians and
laboratory personnel have added absorbent materials to the litter
box to collect the urine and feces (i.e., dross). A major problem
with the absorbent materials is that after a relatively short
period of time, the dross soiled absorbent emits objectionable
odors due to the presence of the urine and fecal matter.
[0004] In order to reduce or eliminate these objectionable odors,
homeowners periodically remove the fecal matter from the absorbent
material(s). However, physical removal of the feces does not reduce
or eliminate odors caused by the urine absorbed into the absorbent.
Therefore, when the odors caused by the absorbed urine become
intolerable, the homeowner discards the absorbent material. The
homeowner then washes the litter box and refills it with fresh
absorbent material. These activities are, however, unpleasant,
time-consuming and expensive.
[0005] The most commonly used absorbent materials are inexpensive
clays, such as dryed or calcined clays, that are safe and
non-irritating to the animals. As is well known in the art, clays
generally absorb relatively substantial amounts of liquids.
[0006] Other porous absorbent materials, that are used alone or in
combination, include straw, sawdust, wood chips, wood shavings,
porous polymeric beads, shredded paper, bark, cloth, ground corn
husks, cellulose, water-insoluble inorganic salts, such as calcium
sulfate, and sand. Although the noted absorbent materials have the
advantage of low cost, each suffers from the disadvantage of merely
absorbing and retaining the liquid dross within its porous
matrices, or, in the case of sand, absorbing the liquid dross on
its surface.
[0007] More recently, litter compositions having bentonite clay
particles have been employed to address the malodor problem arising
from retained urine and fecal matter. As is well known in the art,
bentonite is a water-swellable clay which, upon contact with liquid
(or moist) dross, readily agglomerates with other moistened
bentonite clay particles. The moist animal waste is thus isolated
by the agglomeration of the moist clay particles and can be readily
removed from the litter. Illustrative bentonite based litter
compositions are disclosed in U.S. Pat. Nos. 5,503,111, 5,386,803,
5,317,990, 5,129,365 and U.S. Reissue Pat. No. Re. 33,983.
[0008] Various other litter compositions and techniques have also
been employed to address the malodor problem arising from the
presence of urine and fecal matter, particularly urine. For
example, U.S. Pat. Nos. 3,059,615, 3,029,783, 4,306,516 and
3,892,846 teach the use of fairly strong inorganic or organic acids
to control ammonia formation and, hence, offensive odors.
[0009] Still others have sought to decrease odors by employing a
non-clay substrate to improve the absorption rate of the litter
composition. Illustrative is the alfalfa-based litter composition
disclosed in U.S. Pat. No. 3,923,005. However, the simple change of
substrate limits the litter composition to the particular
substrate's absorptive capacity.
[0010] Unlike other prior art attempts, which merely use a clay or
absorbent plant material, U.S. Pat. No. 5,970,915 teaches the use
of a macroporous silica gel in granular form as the litter
substrate. Odor reduction is, however, primarily addressed by
applying a film of a disinfectant to the inside surface of the
litter box.
[0011] A further drawback of the litter composition disclosed in
the '915. patent, and each of the aforementioned litter
compositions, is the permeation of urine through the litter
composition, which accumulates at the bottom of the litter box.
After a brief period of time, the accumulated urine decomposes,
produces volatile compounds (e.g., ammonia) and, ultimately, emits
offensive odors.
[0012] It is therefore an object of the present invention to
provide an improved litter composition that overcomes the
aforementioned drawbacks and disadvantages that are often
associated with conventional litter compositions.
[0013] It is another object of the invention to provide a low cost,
litter composition that substantially reduces the emanation of
offensive odors from urine and fecal matter disposed therein.
[0014] It is another object of the invention to provide a litter
composition that readily agglomerates upon contact with moist dross
and, hence, facilitates removal of the dross from the
composition.
[0015] It is yet another object of the invention to provide a
litter composition that substantially reduces liquid dross
permeation to the bottom of the litter box.
SUMMARY OF THE INVENTION
[0016] An aspect of the invention includes an animal litter
comprising a substantially particulate silica gel material with a
particle size distribution of 0.15-2 mm.
[0017] Another aspect of the invention includes an animal litter
comprising a substantially particulate silica gel material with a
particle size distribution between 1-2 mm and up to 2% of a
material selected from the group consisting of a fixing agent, a
colorant agent, an anti-bacterial agent, a fragrance, a
supplemental absorbent material, an odor-controlling/inhibiting
active, and mixtures thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Further features and advantages will become apparent from
the following and more particular description of the preferred
embodiments of the invention, as illustrated in the accompanying
drawings, and in which like referenced characters generally refer
to the same parts or elements throughout the views, and in
which:
[0019] FIG. 1 is a partial section, perspective view of a prior art
litter box containing a litter composition; and
[0020] FIG. 2 is a graph illustrating the effect of hydraulic
conductivity on urine penetration.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Before describing the present invention in detail, it is to
be understood that this invention is not limited to particularly
exemplified systems or process parameters as such may, of course,
vary. It is also to be understood that the terminology used herein
is for the purpose of describing particular embodiments of the
invention only, and is not intended to limit the scope of the
invention in any manner.
[0022] All publications, patents and patent applications cited
herein, whether supra or infra, are hereby incorporated by
reference in their entirety to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated by
reference.
[0023] It must be noted that, as used in this specification and the
appended claims, the singular forms "a," "an" and "the" include
plural referents unless the content clearly dictates otherwise.
Thus, for example, reference to a "colorant agent" includes two or
more such agents.
[0024] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention pertains. Although
a number of methods and materials similar or equivalent to those
described herein can be used in the practice of the present
invention, the preferred materials and methods are described
herein.
[0025] All numbers expressing quantities of ingredients,
constituents, reaction conditions, and so forth used in the
specification and claims are to be understood as being modified in
all instances by the term "about". Notwithstanding that the
numerical ranges and parameters setting forth the broad scope of
the subject matter presented herein are approximations, the
numerical values set forth in the specific examples are reported as
precisely as possible. Any numerical value, however, inherently
contain certain errors necessarily resulting from the standard
deviation found in their respective testing measurements.
[0026] As will be appreciated by one having ordinary skill in the
art, the litter compositions of the invention substantially reduce
or eliminate the disadvantages and drawbacks associated with prior
art litter compositions. In one embodiment of the invention, the
litter composition includes at least one primary absorbent material
and a binding agent. In additional embodiments of the invention,
the noted litter composition also includes at least one of the
following components: supplemental absorbent material, a fixing
agent, colorant agent, anti-bacterial agent and/or a fragrance.
Each of the noted litter composition components are discussed in
detail below.
[0027] Referring first to FIG. 1, there is shown a typical litter
box 10 having a litter composition 12 therein. As discussed in
detail above, conventional litter compositions, such as the
composition 12 illustrated in FIG. 1, are generally effective for
isolating urine 14 and fecal matter 16 proximate the surface.
However, in contrast to the litter compositions of the invention,
the conventional litter compositions are generally not effective in
eliminating the accumulation of urine at the bottom of the litter
box 10 (designated generally 18).
[0028] Primary Absorbent Material
[0029] A key component of the litter compositions of the invention
is the primary absorbent material (or substrate). Preferably, the
primary absorbent material comprises silica gel or amorphous
silica, which is preferably formed by acid precipitation of sodium
silicate followed by drying. This material is also referred to as
silica acid or hydrated silica. In a preferred embodiment, the
primary absorbent material comprises silica gel.
[0030] As will be appreciated by one having ordinary skill in the
art, typical silica gel material has a bulk density of 400-600 g/l,
pore volume of approximately 50-250 angstroms and an absorption
capacity of approximately 50%-90%. The material is also white to
semi-translucent and may be either granular or bead shaped.
[0031] In one embodiment of the invention, greater than
approximately 20%, more preferably, 20%-90% of the silica gel
particles exhibit a particle size less than approximately 2 mm.
Even more preferably, 10%-90% of the silica gel particles exhibit a
particle size less than approximately 1 mm. Most preferably,
30%-70% of the silica gel particles exhibit a particle size less
than 1 mm.
[0032] In a further aspect of the invention, the silica gel
particles have a mean particle size less than approximately 2 mm,
more preferably, less than 1 mm. Even more preferably, the silica
gel particles have a mean particle size in the range of
approximately 0.2-1 mm.
[0033] Binding Agent
[0034] As indicated above, the litter compositions of the invention
also include at least one binding agent to induce or facilitate
agglomeration. Preferably, the binding agent or agents include (i)
natural polymers and synthetic derivatives thereof, including, but
not limited to, lignins, gums, starches and polysaccharides, such
as lignin sulfonate, carboxymethylcellulose, hydroxyethylcellulose,
hydroxypropylcellulose, ethylhydroxyethyl cellulose,
methylhydroxypropylcellulose, guar gum, alginates, starch, xanthan
gum, gum acacia, and gum Arabic, (ii) synthetic polymers,
including, but not limited to, polyvinylpyrrolidone, polyethylene
glycol, polyethyleneoxide, acrylate polymers and copolymers,
acrylic emulsions, polyvinyl alcohol, polyvinyl acetate, polyvinyl
pyrrolidine, polyacrylic acid, latexes (e.g., neoprene latex),
superabsorbent polymers (e.g., cross-linked polyacrylates),
flocculating agents (e.g., polycarboxylates), and fluorinated
polymers (e.g., polytetrafluoroethylene), and (iii) inorganic
agglomerating agents, including, but not limited to, soluble
silicates and phosphates, including pyrophosphates and
aluminates.
[0035] In a preferred embodiment of the invention, the binding
agent comprises a polysaccharide gum, more preferably, a
galactomannan gum. As is well known in the art, a galactomannan gum
is a carbohydrate polymer containing D-galactose and D-mannose
units, or other derivatives of such a polymer.
[0036] Galactomannan gums include guar gum, which is the pulverized
endosperm of the seed of either of two leguminous plants (Cyamposis
tetragonalobus and psoraloids), locust bean gum, which is found in
the endosperm of the seeds of the carob tree (Ceratonia siliqua),
and carob gum.
[0037] In a further embodiment, the binding agent comprises a
cellulose ether. A preferred cellulose ester is commercially
available under the trade name METHOCEL.TM..
[0038] Preferably, the binding agent(s) comprise approximately
0.01%-40% of the litter composition, more preferably, at least
approximately 1% of the litter composition. Even more preferably,
the binding agent(s) comprise approximately 5%-20% of the litter
composition.
[0039] As will be disclosed further below, such binding agents may
be optional, since the inventive litters' performance is not
principally dependent on litter clumping or agglomerating around
dross or urine.
[0040] Fixing Agent
[0041] In a further embodiment of the invention, the litter
composition of the invention includes at least one fixing agent to
control the segregation of small particles and, hence, undesirable
dust. According to the invention, the fixing agent facilitates
coating of the moisture activated binding agent to the litter
particles. The amount of the fixing agent present in the litter
composition varies with the amount of binding agent present.
[0042] Preferably, the fixing agent is water-soluble and comprises
up to approximately 6%, by weight, of the litter composition. More
preferably, the fixing agent comprises less than approximately 2%,
by weight, of the litter composition.
[0043] Preferred fixing agents include wheat paste, rice paste,
starch, mucilage, fluoropolymer emulsions, water soluble acrylic
polymers and soluble vinyl polymers, such as polyvinyl acetate.
Particularly preferred fixing agents include acrylic emulsions,
neoprene latex and polyethylene glycol, having an average molecular
weight of at least about 2000, more preferably, at least about
3000. Acrylic polymers or co-polymers from Rhodia, BASF and other
emulsion polymer vendors may be used.
[0044] Colorant Agent
[0045] In yet another embodiment, the litter composition includes
at least one colorant agent. According to the invention, the
colorant agent includes dyes, including, but not limited to, direct
dyes, vat dyes, sulfur dyes, acid dyes, mordant acid dyes,
premetalized acid dyes, basic dyes, dispersed dyes, reactive dyes,
azo dyes, phthalocyanine dyes, anthraquinone dye, quinoline dyes,
monoazo, disazo and polyazo dyes. Preferred dyes include
anthraquinone, quinoline and monoazo dyes. Especially preferred
dyes are polymeric dyes (e.g., dyes that are covalently bonded to
polymers). The colorant agent can also include a pigment (e.g.,
phthalo pigments, ultramarine blue (UMB), titanium dioxide
(TiO.sub.2) or others, whether of synthetic or natural origin).
[0046] Preferably, the colorant agent comprises up to approximately
5% of the litter composition, more preferably, 0.001%-1% of the
litter composition. Even more preferably, the colorant agent
comprises approximately 0.001%-0.01% of the litter composition.
[0047] In a further aspect of the invention, the colorant agent is
disposed on at least 10% of the primary absorbent material (e.g.,
silica gel). More preferably, the colorant agent is disposed on at
least 20% of the primary absorbent material.
[0048] According to the invention, the dyes and pigments may be any
color, even yellow. An effective amount of dye or pigment is that
which is perceived by consumers to be preferred over uncolored
litter. As is well known in the art, one method of assessing the
effectiveness of the dye or pigment is by measuring the litter
composition resistance to color changes in the b region of the
L.a.b color scale when soiled by animal urine. The L,a,b color
scale is a uniform color system developed by Hunterlab to represent
color. See, e.g., Kirk-Othmer, Encyclopedia of Chemical Technology,
4.sup.th Ed., Vol. 11, pg. 238 (1994); Instruments and Test Methods
for Control of Whiteness in Textile Mills, Proceedings of the
American Association of Textile chemists and Colorists, 1966
National Technical Conference (1966).
[0049] As discussed in detail below, Applicants have found that the
colored litter compositions of the invention substantially resist
color changes in the b region of the L.a.b color scale when soiled
with animal urine. More particularly, the color change in the b
region is less than 10 units.
[0050] Moreover, color of the litter may be esthetically preferred
by the consumer and a color change may help signal the consumer
about the need to change, clean or dispose of the used litter.
[0051] Anti-Bacterial Agent
[0052] As indicated above, the litter compositions of the invention
can further include at least one anti-bacterial agent (or
antimicrobial and/or urease inhibitor) as an odor control agent.
One class of anti-bacterial or odor control agents is transition
metal ions and their soluble salts. Preferred transition metals
include silver, copper, zinc, ferric and aluminum salts. More
preferably, the transition metal comprises zinc.
[0053] Other odor control anti-bacterial agents include sulfuric
acid, phosphoric acid, hydroxamic acid, thiourea, iodophores,
3-isothiazolones, salts of phytic acid, plant extracts, pine oil,
naturally occurring acids and antimicrobials, such as quaternary
ammonium compounds, organic sulfur compounds, halogenated phenols,
hexachlorophene, 2,4,4'-trichloro-2'-hydr- oxydiphenyl ether,
trichiorocarbanalide, 2,4-dichloro-meta-xylenol,
3,4,5-tribromosalicylanalide, 3,5,3',4'-tetrachlorosalicylanalide,
and mixtures thereof. Some of these odor control anti-bacterial
agents can be added to litters to function as bacteriostats, ie.,
they are present in relatively low amounts to ensure lack of or
minimalodor by transiently present bacteria which may act on the
unused litter ingredients to produce off-odors or signal to the
consumer that the product is "not fresh." Some of the preferred
bacteriostats include a number of materials produced by Rohm and
Haas under the brand name Kathon.
[0054] Additional odor control (or odor-absorbing) agents include
carbonates, bicarbonates, cyclodextrins, zeolites, activated
carbon, kieselguhr, chelating agents, chitin and pH buffered
materials, such as carboxylic acids and the like. Preferred agents
are those which absorb primary amines.
[0055] In a further aspect of the invention, enzymes are employed
as odor control agents. The enzymes include ureases and proteases,
such as pepsin, tripsin, ficin, bromelin, papain, rennin, and
mixtures thereof.
[0056] A particularly preferred class of odor control agents is
boron compounds, including borax pentahydrate, borax decahydrate
and boric acid. Polyborate, tetraboric acid, sodium metaborate and
other forms of boron are also appropriate alternative materials.
Other boron-based compounds potentially suitable for use are
disclosed in Kirk-Othmer, Encyclopedia of Chemical Technology,
3.sup.rd Ed., Vol. 4, pp. 67-109 (1978), which is incorporated by
reference herein.
[0057] Applicants have found that borax provides multiple benefits
in odor control by: (1) acting as a urease inhibitor, which
controls odors by preventing enzymatic breakdown of urea; and (2)
exhibiting bacteriostatic properties, which appear to help control
odor by controlling the growth of bacteria which are responsible
for production of the urease enzymes. Applicants have further found
that an odor controlling effective amount comprises at least about
0.02% equivalent boron, more preferably, greater than 0.03%
equivalent boron.
[0058] Preferably, the anti-bacterial agent comprises approximately
0.02%-1%, by weight, of the litter composition. More preferably,
the anti-bacterial agent comprises approximately 0.02%-0.75%, by
weight, of the litter composition. Even more preferably, the
anti-bacterial agent comprises approximately 0.02%-0.15%, by
weight, of the litter composition. As will be appreciated by one
skilled in the art, the compositional levels can be adjusted to
ensure effective odor control and cost effectiveness.
[0059] Fragrance
[0060] In a further aspect of the invention, the litter composition
includes one or more fragrances to provide a freshness or
deodorizing impression to humans or serve as an attractant
fragrance to animals. Although some "free" fragrance can be
present, it is preferably that at least a major part of the
fragrance (or perfume) be contained or encapsulated in a carrier to
prevent premature loss to the atmosphere, as well as to avoid a
strong fragrance odor which can be uncomfortable to the animals.
According to the invention, the encapsulation can be in the form of
molecular encapsulation, such as the inclusion complex with
cyclodextrin, coacevate microencapsulation wherein the fragrance
droplet is enclosed in a solid wall material, or "cellular matrix"
encapsulation wherein solid particles containing perfume droplets
stably held in the cells. Fragrance can also be more crudely
embedded in a matrix, such as a starch or sugar matrix.
[0061] The encapsulated fragrance can be released either by
moisture activation and/or a pressure activation mechanism.
Moisture-activated microcapsules release fragrance upon being
wetted, e.g., by the animal urine. Pressure-activated microcapsules
release fragrance when the shell wall is broken by, e.g., the
scratching or stepping of the animals on the litter. Some
microcapsules can be activated both by moisture and pressure.
[0062] The animal litter of the present invention can also contain
pro-fragrances. A pro-fragrance is a normally nonvolatile molecule
which consists of a volatile fragrance ingredient covalently bonded
to another moiety by a labile covalent bond. In use, the
pro-fragrance is decomposed to release the volatile fragrance
ingredient. Preferred pro-fragrances include complexes of
bisulfite, with fragrance ingredients having an aldehyde or ketone
functional groups, and esters of phosphoric acids, and sulfuric
acids with fragrance ingredients having a hydroxyl group.
[0063] Preferably, the fragrance comprises approximately 0.001%-1%,
by weight, of the litter composition, more preferably,
approximately 0.005%-0.5%, by weight, of the litter composition.
Even more preferably, the fragrance comprises approximately
0.01%-0.2%, by weight, of the litter composition.
[0064] Supplemental Absorbent Material
[0065] As indicated above, the litter composition of the invention
can further include one or more supplemental absorbent materials.
Preferred supplemental absorbent materials include (i) minerals,
such as Georgia White clay, sepiolite, zeolite, calcite, dolomite,
slate, pumice, tobermite, marls, attapulgite, bentonite, kaolinite,
halloysite, montmorillonite, smectite, vermiculite, hectorite,
diatomaceous earth, Fuller's earth, fossilized plant materials,
expanded perlites, gypsum and other similar minerals and (ii) other
natural and processed materials, such as paper, cellulosic webs,
polymeric fibrous webs, wood chips, alfalfa, bark, straw, sand,
grain hulls, synthetic foams, recycled materials, and pelletized
absorbing litter materials. The supplemental absorbent materials
can also comprise mixtures of the noted materials.
[0066] According to the invention, the supplemental absorbent
agents, if employed, comprise up to approximately 60%, by weight,
of the litter composition, more preferably up to approximately 40%,
by weight, of the litter composition. Even more preferably, the
supplemental absorbent agent(s) comprise up to approximately 30%,
by weight, of the litter composition.
[0067] Odor Controlling Agents
[0068] In a further aspect of the invention, the litter composition
includes one or more odor controlling agents in the form of odor
absorbing/inhibiting actives to minimize the formation of odors.
Actives of these types may work by preventing the causes of the
odor, such as inhibiting the bacteria that create the odors, or by
preventing the odors from being detected, such as absorbing,
encasing, or neutralizing the odor. An illustrative material is a
water soluble metal salt such as silver, copper, zinc, iron, and
aluminum salts and mixtures thereof. Examples of metallic salts
include zinc chloride, zinc gluconate, zinc lactate, zinc maleate,
zinc salicylate, zinc sulfate, zinc ricinoleate, copper chloride,
copper gluconate, and mixtures thereof. Other odor control actives
include nanoparticles that may be composed of many different
materials such as carbon, metals, metal halides or oxides, or other
materials. Additional types of odor absorbing/inhibiting actives
include cyclodextrin, zeolites, silicas, activated carbon (also
known as activated charcoal), acidic, salt-forming materials, and
mixtures thereof. Activated alumina (Al.sub.2O.sub.3) has been
found to provide odor control comparable and even superior to other
odor control additives such as activated carbon, zeolites, and
silica gel. Alumina is a white granular material, and is properly
called aluminum oxide.
[0069] In another aspect of the invention, the odor
absorbing/inhibiting active is Powdered Activated Carbon (PAC),
though Granular Activated Carbon (GAC) can also be used. PAC gives
much greater surface area than GAC (GAC is something larger than
powder (e.g., .gtoreq.80 mesh U.S. Standard Sieve (U.S.S.S.))), and
thus has more sites with which to trap odor-causing materials and
is therefore more effective. PAC has only rarely been used in
absorbent particles, and particularly animal litter, as it tends to
segregate out of the litter during shipping, thereby creating
excessive dust (also known as "sifting"). By attaching PAC onto the
primary or supplemental absorbent material with a fixing agent, the
present invention overcomes the problems with carbon settling out
during shipping. Generally, the preferred mean particle diameter of
the carbon particles used is less than about 500 microns, but can
be larger. The particle size can also be much smaller (less than
100 nanometers) as in the case of carbon nanoparticles. The
preferred particle size of the PAC is about 150 microns (.about.100
mesh U.S.S.S.) or less, and ideally in the range of about 25 to 150
microns, with a mean diameter of about 50 microns (.about.325 mesh
U.S.S.S.) or less. The following examples illustrate the litter
compositions of the invention. The examples are for illustrative
purposes only and are not meant to limit the scope of the invention
in any way.
EXAMPLES
[0070] Various samples of litter compositions of the invention were
prepared and investigated to determine the following
characteristics: (i) agglomerate or clump strength, (ii) hydraulic
conductivity, (iii) urine penetration, (iv) clump aspect ratio, (v)
sensory perception, (vi) colorimetry, and (vii) and dynamic
absorption (measured against bulk density and particle size). The
results of the investigation are set forth below.
[0071] Clump Strength
[0072] In addition to odor control, agglomerate or clump strength
is a significant performance characteristic of a silica gel based
litter composition. To investigate clump strength of the litter
composition(s), clumps were produced using actual feline urine. The
clumps were first weighed, shaken on a coarse screen, and measured
for weight loss. Clump strength was thus the percentage of the
remaining litter after shaking of the clump; a clump strength of
100% indicating that none of the material fell away from the urine
clump, and a clump strength of 0% indicating that the clump fell
completely apart.
[0073] Although a litter composition could be made of silica gel
alone, it would not have the beneficial properties of "clumping"
that the consumer desires to help remove the waste from the litter.
A moisture-activated binder could be added through simple addition,
but, the binder would have a tendency to segregate to the bottom of
the box and lower the strength of the litter clumps. However, the
addition of a fixing agent, which attaches the moisture-activated
binder to the silica gel particles, creates an improved litter
composition that retains its ability to form strong clumps even
when agitated.
[0074] Referring now to Tables IA and IB, there is shown the clump
strength of several litter compositions of the invention, wherein
"SG" denotes silica gel, "GG" denotes guar gum, and "FA" denotes
fixing agent. Each of the compositions was tested "as-made" and
then shaken for 30 seconds to simulate conditions of
segregation.
[0075] In Samples 1 and 2, the silica gel alone provided virtually
no clump strength, either before or after shaking. Further, as
expected, the clumps fell apart when tested.
[0076] In Samples 3 and 4, the silica gel and guar gum compositions
provided adequate clump strength of 87% and 65%, respectively.
However, shaking caused the guar to segregate to the bottom of each
composition. The resulting compositions thus exhibited post-shaking
clump strength of 14% and 8%, respectively.
[0077] As illustrated by Sample 5, the litter co position can be
substantially improved by adding a fixing agent. In the noted
sample, the clump strength started at 93% and maintained a strong
90% strength even after shaking.
[0078] Referring to Sample 6, the clump strength was further
improved by decreasing the particle size of the silica gel. The
clump strength also remained high even after shaking.
1 TABLE IA Sample 1 Sample 2 Sample 3 Composition 1-2 mm SG 2-8 mm
SG 1-2 mm SG 1.5% GG Clump strength* 0% 0% 87% (blended) Clump
strength* 0% 0% 14% after shaking *Measured as the remaining
portion of actual feline litter clumps after agitation on a 0.5 in.
screen for 5 sec.
[0079]
2 TABLE IB Sample 4 Sample 5 Sample 6 Composition 2-8 mm SG 1-2 mm
SG 0.15-2 mm SG 1.5% GG 1.5% GG 1.5% GG 0.66% FA 0.66% FA Clump
strength* 65% 93% 94% (blended) Clump strength* 8% 90% 92% after
shaking
[0080] Hydraulic Conductivity
[0081] As is well known in the art, hydraulic conductivity, which
reflects the ability of a porous medium to transmit water through
its interconnected voids, is one of the most important
characteristics of water absorbing substrates. Hydraulic
conductivity can thus be defined as the ease with which liquids
pass through a substrate, and is dependent largely on the size and
shape of the void spaces between individual particles in the
substrate.
[0082] It is further well known that Darcy's law describes the
relationship between the movement of a liquid through a porous
substrate, and the hydraulic head difference in the water at the
top and bottom of the substrate, i.e.,
Q=KA(ha-hb)/L Eq. 1
[0083] wherein:
[0084] Q=Flow rate
[0085] K=Hydraulic Conductivity
[0086] A=Cross Sectional Area
[0087] L=Length of the Sediment
[0088] ha-hb=Hydraulic Head
[0089] By utilizing a K value (hydraulic conductivity)
determination, particle size distribution of the litter substrate
can be optimized to reduce permeability, making the urine path
through the litter more tortuous and reducing the depth of urine
penetration. This makes it more difficult for the urine to reach
the bottom of the litter box and minimizes accumulation of urine
and the problems associated with the accumulation urine mentioned
above.
[0090] As will be appreciated by one having ordinary skill in the
art, silica gels of different particle size distributions will give
different values for permeability or hydraulic conductivity (K),
following ASTM method D2434-68 (2000). It has however surprisingly
been found that particle size distributions of the litter
compositions of the invention that exhibit hydraulic conductivities
below 0.25 cm/s can substantially decrease urine penetration in a
standard litter box.
[0091] Referring to Table II, there is shown the effect of particle
size distribution on hydraulic conductivity. It can be seen that
the addition of smaller particle size silica gel to the litter
composition inhibits flow and decreases the hydraulic conductivity
compared to larger particle size litter compositions.
[0092] Referring now to FIG. 2, there is shown the effect of
hydraulic conductivity (K) on penetration of urine. As illustrated
in FIG. 2, penetration generally decreases as the K value
decreases. Thus, a low K value allows the consumer to use less
litter while preventing penetration.
[0093] Penetration and Clump Aspect Ratio
[0094] Penetration is determined by measuring height of the clump
formed in the formula using feline urine. Another way of
determining the penetration is by measuring the clump aspect ratio.
The aspect ratio is calculated by comparing the maximum width of
the clump to the maximum height of the clump. When litter product
was made with particle size distributions of silica gel with low
hydraulic conductivity, clumps looked pancake shaped (high aspect
ratio) rather than egg shaped (low aspect ratio). These pancake
shaped clumps are surprisingly easier for pet owners to dispose. As
illustrated in Table II, particle size distributions of the litter
compositions of the invention provide more favorable penetration
values and clump aspect ratios.
3 TABLE II Sample Sample Sample Sample Base 7 8 9 10 1-2 mm >93%
50% 40% 35% 35% 0.2-1.5 mm 50% 50% 50% 45% 0.15-0.6 mm 10% 15% 20%
Hydraulic conductivity 0.25 0.125 0.05 0.025 0.02 (cm/s) Urine
penetrates more Yes No No No No than 2.54 cm (1 inch)* Clump Aspect
Ratio 1.8 2.0 3.3 3.8 3.1 (Width to Height) *Urine penetration
determined by lab testing with 10 ml of feline urine
[0095] When litter product was made with a particle size
distribution of silica gel with low hydraulic conductivity, the
liquid traveled only a short distance through the litter. Litters
that prevent penetration of the urine to the bottom of the box
limit the amount of free urine in the box and thus prevent the
formation of ammonia and unpleasant odor.
[0096] Sensory Testing
[0097] Referring to Table III, there is shown the effect of
coloration on the perception of litter. Cat litter users were asked
to judge samples of litter on a 60 point scale from Clean (60) to
Dirty (0). Samples were prepared with increasing levels of blue
coloration on the silica, and were dosed with urine to represent
used litter. The levels of urine in each sample were equal, but the
panelist's perception of how clean the litter was improved with
increasing coloration.
4TABLE III Level of Colorant Clean Perception 5% Blue colored
particles 21 100% colored silica gel with (a) 0.000375% Acid Blue 9
24 (b) 0.00125% Acid Blue 9 32 (c) 0.00050% Acid Blue 9/0.00075%
Wool Violet 37 (d) 0.025% UMB 29 (e) 0.0028% Acid Blue 9 40
[0098] Consumer perception of a negative discoloration is also
influenced by the percent of colored particles. Referring to Table
IV, there is shown the effect of the percent of colored particles
on the perception of yellow.
[0099] In the noted investigation, 10 ml of feline urine was
pipetted on a silica gel and binding agent litter composition of
the invention. The clumps formed on the surface of the litter
composition were then judged for the perception of yellow. As
illustrated in Table IV, even adding color to 50% of the particles
substantially reduced the yellow perception of the litter
composition after one simulated usage.
5 TABLE IV Perception of yellow color Percent of colored particles
(0-60, where 60 is yellow) 0% 28 50% 24 100% 19
[0100] Colorimetric Testing
[0101] Preferred colorants can also be determined by their ability
to resist color change in the b region of the L.a.b color scale. As
indicated above, the L.a.b scale is an industry standard used for
the measurement of color. It is comprised of 3 perpendicular color
axes (L, a and b) that define a three-dimensional color space.
[0102] A litter composition sample was prepared by dosing 10 ml of
cat urine onto one area of the sample. The soiled sample was placed
in a plastic petri dish and covered to compress the sample. The
sample was then read on a Hunter calorimeter to measure the change
in b value compared to a comparable litter composition sample
treated with 10 ml of water.
[0103] Referring to Table V, there is shown the effect of various
percentages of colored particles on the ability of the litter
composition to hide yellow color by minimizing shifts in a positive
b direction. The b axis of the scale measures yellow to blue.
[0104] As illustrated in Table V, when soiled with urine, uncolored
silica gel shifts 16 units on the b scale in the direction of the
color yellow. However, soiled 75% blue silica gel only shifts 1
unit on the b scale compared to uncolored silica, which evidences
its ability to hide the perception of a yellow color. Even a litter
composition containing 25% colored silica gel reduces the shift in
the b scale to 5 units.
6 TABLE V Sample Sample Sample Sample Sample Percentage of Colored
0% 5% 25% 50% 75% Speckles in Silica Gel (blue) Yellow shift when
16.0 9.1 5.0 2.5 0.7 soiled (b scale)
V. Dynamic Absorption vs. Particle Size and Bulk Density
[0105] Table VI, illustrates the relationship of particle size and
its related bulk density on dynamic absorption. Significant benefit
is observed from a narrow particle size distribution even when no
binding agent is used. The silica gel raw material used for this
testing was from the same base material, i.e. all made by the same
process, screened to different size fractions. Consequently, the
true particle density of the various materials was equivalent, as
well as the inherent pore volumes. The noted bulk density
differences arose from variations in particle packing as a result
of the respective particle size distributions. As the dynamic
absorption of the material increases, the hydraulic conductivity
decreases.
7TABLE VI Particle Size Bulk Density, g/L Dynamic Absorption, wt %
(1.5" bed) 2-8 mm 432 67% 1-4 mm 377 102% 1-2 mm 365 134%
[0106] It would have been expected that the more efficiently packed
bed of 2-8 mm particles would have displayed the greatest dynamic
absorption capacity, since the lower void volume would be expected
to maximize the liquid-particle contact and the tortuosity of the
path that the liquid would need to follow in order to pass through
the column. Comparing the size range of 1-2 mm with a size range of
1-4 mm, the lower density fraction surprisingly yielded the highest
dynamic absorption, capacity. Similar results would also be
expected for particles in smaller size ranges (e.g., 0.15-1 mm)
[0107] Higher dynamic absorption inhibits urine from penetrating
through the litter bed and pooling in the bottom of the litter box
and/or coating the bottom of the box with a biofilm. Consumers want
their litter box to appear dry, i.e. they want the litter product
to absorb all visible wetness. Further, the development of a
biofilm on the surfaces of the litter box is known by those skilled
in the art to increase litter box malodor due to the release of a
malodorous gases and/or the creation of malodorous byproducts as a
result of bacterial growth and metabolism of the waste (e.g.,
ammonia). The desiccating properties of the litter substrate (e.g.
silica gel) inhibit the proliferation of these bacteria; however,
when the waste is able to reach the non-porous (e.g., plastic)
litter box surface, there is no such inhibition of bacterial growth
and proliferation.
[0108] Reducing the permeability of the bed also inhibits the
permeation of (gaseous) malodors, from waste buried in the bed, to
the surface of the bed, thereby reducing perceived malodors
emanating from the litter box.
[0109] Solid waste can easily be removed from the litter box,
without undue waste of the litter substrate. The finer particle
size of the litter disclosed herein allows those litter particles
which are not adhered to the solid waste to easily fall back
through the slots of the litter scoop, into the bed of remaining
litter. Additionally, the litter disclosed herein is much more
easily raked or stirred with conventional litter scoops than those
of the broader range particle size litters presently known in the
art. The consumer is directed to stir the litter after scooping out
solid waste, in between litter box changes. This results in
dispersion of urine-containing particles throughout the litter bed,
which in turn reduces malodor and encourages evaporation of the
water component of the waste, thereby increasing the remaining
liquid absorption capacity of the litter bed. Finally, more
efficient stirring improves the aesthetics of the litter bed. All
of these improvements prolong the life of the litter by rendering
it acceptable to the consumer for a longer period of time.
VI. Examples of Embodiments
[0110] Disclosed herein are silica gel litters with size
distributions ranging from 0.15-4 mm. One embodiment comprises at
least 90% of the silica gel particles being in the 1-2 mm in size.
A further embodiment comprises silica gel particles in the size
range between 1-4 mm wherein the mean particle size is between 1-2
mm. A further embodiment comprises silica gel particles in the size
range between 1-2 mm wherein the mean particle size is between
1-1.5 mm. In another embodiment, the silica gel material has a mean
particle size between 1-4 mm. Fixing agents, antibacterial agents,
colorants, fragrances and supplemental absorbent materials may be
added as discussed above. The silica gel particles may comprise
type A, B, C, or macroporous silica gel and mixtures thereof.
[0111] Table VII depicts one mode of the invention where amorphous
silica gel was treated with a color preblend. The preblend was an
aqueous solution having up to 5% of a long polymer dye to help hide
the color of the waste, up to 50% bf an acrylic polymer to control
dust, and up to 0.75% of preservative. The amorphous silica gel
comprises >90% and the blue preblend solution comprises up to 5%
of the total weight of the litter composition. The ingredients and
amounts were chosen to result in a litter having predictable odor
control and cost-effectiveness. In addition, ease of production was
a major consideration. It should be noted that water is a
relatively major portion of the formulation since it is present in
the liquid ingredients as a solvent, as well as a natural component
of minerals as residual or bound moisture.
8TABLE VII Ingredient % Weight Details Amorphous Silica Gel >90%
Particle size ranging from 0.15-4 mm Blue Preblend Solution Up to
5% Long polymer dye (blue color) Up to 5% Acrylic polymer (Rhoplex)
Up to 50% Preservative (Kathon) Up to 0.75% Water - q.s.
[0112] Without departing from the spirit and scope of this
invention, one of ordinary skill can make various changes and
modifications to the invention to adapt it to various usages and
conditions. As such, these changes and modifications are properly,
equitably, and intended to be, within the full range of equivalence
of the following claims.
* * * * *