Note: Descriptions are shown in the official language in which they were submitted.
lZ9Z65~7
THICKENED AQUEOUS COMPOSlTiONS
WITH SUSPENDED SOLIDS
Brian J. Roselle
Technical Field and Background Art
This inventi~n relates to aqueous liquid compositions which
5 have a yield value and are shear-thinning comprising suspended
particles having a density greater than that of the continuous
aqueous liquid phase. Compositions of this type are well known,
especially where the composition is a detergent composition.
Examples of such compositions are disclosed in U . S. Patent
3,075,922-Wixon, issued Jan. 29, 1963; U.S. Patent
3,985,668-Hartman,issued Oct. 12, 1976; U.S. Patent
4,116,849-Leikhim,issued Sept. 26, 1978; U.S. Patent
4,116,851-Rupe etal, issued Sept. 26, 1978; U.S. Patent
4,162,987-Maguire,Jr. et al, issued July 31, 1979; U.S. Patent
4,431,559-Ulrich, issued Feb. 14, 1984; U.S. Patent
4,511,487-Pruhs et al, issued April 16, 1985; U.S. Patent
4,512,908-Heile, issued April 23, 1985; U.S-. Patent -
4,561,994-Rubin et al, issued Dec. 31, 1985 and British Patent
Application 2,116,199A-Julemont et al, published Sept. 21, 1983~
U.S. Patent 3,985,668, discloses that a light water-insoluble particulate fillermaterial is a desirable ingredient of such compositions to improve stability. Also,
Japanese Patent Application J60076598-A, published May 5, 1985 discloses that
air bubbles 50-700 microns in diameter improve separation stability in light duty
5 liquid compositions containing suspended abrasives.
Summarv of the Invention
According to one aspect of the invention there is provided an aqueous
liquid, shear-thinning automatic dishwashing detergent composition comprising:
(1) from 0% to about 3% of bleach-stable, low foaming detergent surfactant; (2)
30 from about 10% to about 40% of detergency builder; (3) hypochlorite bleach toyield available chlorine in an amount of from about 0.3% to about 2.5%; (4) fromabout 0.1% to about 10% of thickening agent; and (5) the balance a continuous
phase of aqueous liquid, said composition having: (a) a yield value of from about
35 20 to about 500 dynes/cm2; (b) from about 10% to about 40% of s~id detergencybuilder in the form of solid suspended particles which do not dissolve in said
continuous aqueous liquid phase, which have a density greater than that of the
continuous liquid phase, and which have a particle size range of from about 2
microns to about 500 microns; and (c) entrained gas selected from the group
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consisting of air, nitrogen, carbon dioxide, oxygen, helium, and mixtures thereof,
in the form of bubbles having a maxim~lm diameter of less than abo~lt 1/8 inch,
in an amount to adjust the overall specific gravity of the composition to withinfrom about 3% more than to about 10% less than the specific gravity of the
aqueous liquid by itself.
Detailed Description of The Invention
5 The Aqueous Liquid
Water is the principle component of the aqueous liquid which
is the continuous phase in the compositions of this invention. In
addition, the aciueous liquid can contain a number of other compo-
nents dissolved in the aqueous liquid. It is preferred that the
10 water used to prepare the aqueous liquid component contain, at
most, minimal amounts of dissolved impurities.
The aqueous liquid normally comprises from about 30% to
about 90% by weight, preferably from about 5596 to about 90% by
weight of the total composition.
15 The Thickening Agent
Any material or materials which can be admixed with the
- aqueous liquid to provide~ shear-thinning compositions having
sufficient yield values can be used in the compositions of this
invention. The most common thickening agents are clays, but
20 materials such as colloidal silica, particulate polymers, such as
polystyrene and oxidized polystyrene, combinations of certain
surfactants, and water soluble polymers such as polyacrylate are
also known to provide yield values.
The most preferred thickening agents are nat4rally occurring
25 and synthetic clays.
A preferred synthetlc clay is the one disclosed in U . S.
Patent 3,843,548. Naturally
occurring clays include smectites and attapulgites. These
colloldal materials can be described as expandable layered clays,
30 I.e., aluminoslllcates and magnesium silicates. The term
expandable as used to describe the instant clays relates to the
ability of the layered clay structure to be swollen, or expanded,
on contact with water. The expandable clays used herein are
those materials classified geologically as smectites (or
35 montmorillonoids) and attapulgites (or palygorskites).
~'
1~9Z~57
Smectites are three-layered clays. There are two distlnct
classes of smectite-clays. In the first, aluminum oxide is present
in the silicate crystal lattice; in the second class of smectites,
magnesium oxide is present in the silicate crystal lattice. The
5 general formulas of these smectites are Al2tSi2O5)2(OH)2 and
Mg3(5i2O5) (OH)2, for the aluminum and magnesium oxide type
clays, respectively. It is to be recognized that the range of the
water of hydration in the above formulas can vary with the
processing to which the clay has been subjected. This is imma-
10 terial to the use of the smectite clays in the present compositionsin that the expandable characteristics of the hydrated clays are
dictated by the silicate lattice structure. Furthermore, atom
substitution by iron and magnesium can occur within the crystal
lattice of the smectites, while metal cations such as Na and Ca,
15 as well as H , can be copresent in the water of hydration to
provide electrical neutrality. Although the presence of iron in
such clay material is preferably avoided to minimize adverse
- reactions, e.g., a chemical interaction between clay and bleach,
such cation substitutions in general are immaterial to the use of
20 the clays herein since the desirable physical properties of the
clay are not substantially altered thereby.
The layered expandable aluminosilicate smectite clays useful
herein are further characterized by a dioctahedral crystal lattice,
whereas the expandable magnesium silicate clays have a
25 trioctahedral crystal lattlce.
The smectite clays used in the composltions herein are all
commercially available. such clays include for example,
montmorlllonlte (bentonite), volchonskoite, nontronite, beidellite,
hectorite, saponite, sauconite and vermiculite. The clays herein
30 are available ùnder commercial name5 such as Fooler Clay (clay
found in a relatively thin vein above the main bentonite or
montmorillonite velns in the Black Hilis) and various trade marks
such as Thixogel No. 1 and Gelwhite GP from ECC America, Inc.
(both montmorillonites); Volclay BC, Volclay No. 325, and
35 especially Volclay HPM-20 from American Colloid Company, Skokie,
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,; Illinois; Black Hills Bentonite BH 450, from International Minerals
and Chemicals Veegum Pro and Veegum F, from R. T. Vanderbilt
(both hectorites) Barasym NAS-100, Barasym NAH-100, Barasym
SMM~ 200, and Barasym LIH-200, all synthetic hectorites and
saponites marketed by Baroid Division, NL, Industries, Inc.
Smectite clays are preferred for use in the instant invention.
Montmorillonite, hectorite and saponite are the preferred smec-
tites. Gelwhite GP, Barasym NAS-100, Barasym NAH-100, and
HPM-20 are the preferred montmorillonites, hectorites and sapon-
ites.
A second type of expandable clay material useful in the
instant invention is classified geologically as attapulgite (paly-
gorskite). Attapulgites are magnesium-rich clays having prin-
ciples of superposition of tetrahedral and octahedral unit cell
elements different from the smectites. An idealized composition of
the attapulgite unit cell is given as:
- (oH2)4(H)2Ms55i8o2o-4H2o-
A typical attapulgite analyses yields 55.0296 SiO2; 10.249
Al2O3; 3.53~ Fe2o3; 10.45% MgO; 0.47% K2O; 9.73% H2O removed
at 150 C.; 10.13% ~i2O removed at higher temperatures.
Like the smectites, attapulgite clays are commercially avail-
able. For example, such clays are marketed under the trademark
Attagel, i . e. Attagel 40, Attagel 50 and Attagel 150 from
Engelhard Minerals ~ Chemicals Corporation.
Particularly preferred for the colloid-forrning clay component
in certain embodiments of the instant composition are mixtures of
smectite and attapulgite clays. in general, such mixed clay
composltions exhibit increased and prolonged fluidity upon appli-
cation of shear stress but are still adequately thickened solutions
at times when flow is not desired. Clay mixtures in a
smectite/attapulgite weight ratio of from 5:1 to 1:5 are preferred.
Ratlos of from 2 :1 to 1: 2 are more preferred . A ratio of about
1:1 is most preferred.
.}. .,;
As noted above, the clays employed in the compositions of
the present invention contain cationic counter ions such as pro-
tons, sodium ions, potassium ions, calcium ions, magnesium ions
and the like. It is customary to distinguish between clays on the
s basis of one cation which Is predominately or exclusively ab-
sorbed. For example a sodium clay is one in which the absorbed
cation is predominately sodium. Such absorbed cations can be-
come involved in exchange reactions with cations present in
aqueous solutions. It is preferred that the present compositions
10 contain up to about 12~ or preferably up to about 8% potassium
ions since they improve the viscosity increasing characteristics of
the clay. Preferably at least 1%, more preferably at least 2% of
the potassium ions are present.
Hectorites can also be used, particularly those of the types described
in U.S. Patents 4,511,487 and 4,512,908.
- Specific preferred clays are disclosed in U.S. Patent Nos. 3,993,573 and
4,005,027. These materials are preferred for thickening. The amount of clay
will normally be from about 1/4% to about 20%, preferably from about 0.5%
20 to about 12%, more preferably from about 0.5% to about 2%.
Other thickening agents which are useful in the process aspect of this
invention include those disclosed in U.S. Patent No. 3,393,153, including
colloidal silica having a mean particle diameter ranging from about
0.01 micron to about 0.05 micron and particulate polymers such as
polystyrene, oxidized polystyrene having an acTd number of from
20 to about 40, sulfonated polystyrene having an acid number of
from about 10 to about 30, polyethylene, oxidized polyethylene
having an acid number of from about 10 to about 30; sulfonated
polyethylene having an acid number of from about 5 to about 25;
polypropylene, oxidlzed polypropylene having an acid number of
from about 10 to about 30 and sulfonated polypropylene having an
acid number of from about 5 to about 25, all of said particulate
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~'~ polymers having mean particle diameters ranging from about 0.01
micron to about 30 microns. Other examples include copolymers
of styrene with monomers such as maleic anhydride, nitrilonitrile,
methaacrylic acid and lower alkyl esters of methacrylic acid.
5 Other materials include copolymers of styrene with methyl or ethyl
acrylate, methyl or ethyl maleate, vinyl acetate, acrylic maleic or
fumaric acids and mixtures thereof. The mole ratio of ester
and/or acid to styrene being in the range from about 4 to about
40 styrene units per ester andlor acid unit. The latter materials
10 having a mean particle diameter range of from about 0.05 micron
to about 1 micron and molecular weights ranging from about
500,000 to about 2,000,000.
Other preferred thickening agents include polycarboxylate
polymers, e.g., polyacrylates, polymethacrylates, etc. and
15 copolymers of such monomers with other monomers such as
ethylene, etc.
Still other thickening agents useful herein are described in
U.S. Patent 4,226,736-Bush et al, issued Oct. 7, 1980.
. .
The compositions contain from about 0.1% to about 20%,
preferably from about 0. 3% to about 15%, most preferably from
about 0.5~ to about 5% of thlckening agent.
The thickening agents are used to provide a yield value of
from about 20 to about 500, preferably from ?bout 50 to about
25 350, and most preferably from about 100 to about 250.
Yleld Value Analysis
The yleld value Is an Indication of the shear stress at whlch
the gel strength is exceeded and flow is initiated. It Is measured
herein with a Contravis Rheomat 115 viscometer utilizing a
30 Rheoscan 100 controller and a DIN145 splndle at 25C. The shear
rate rises linearly from 0 to 0.4 sec 1 over a period of 10 minutes
after an Initial 5 minute rest perlod.
The Entrained Gas
The entrained gas can be any gaseous material that is insol-
35 uble In the aqueous liquid. Air is preferred, but any gas that
~ ~ '
.
A
1~32657
will not react with the composition, such as nitrogen, is also
useful,
The entrained gas bubbles are preferably in very finely
divided form, i . e. Iess than about ~ in diameter, preferably less
5 than about 1/32 in. in diameter. They are dispersed throughout
the aqueous liquid in an amount, generally from about 1% to about
20%, preferably from about 5% to about 15% by voiume, to lower
the specific gravity of the overall composition to within from
about 5% more than to about 10% less than, preferably within from
10 about 1% more than to about 5% less than the specific gravity of
the aqueous liquid without the entrained gas. It is more
desirable to be below the specific gravity of the aqueous phase.
Any separation is then at the bottom of the container and pouring
will tend to remix the separated phase before it is dispensed.
The gas can be admixed with high shear mixing, e.g.,
through a shear device that has close tolerances to achieve air
bubble size reduction. High shear mixing can be attained with
shear rates greater than about- 1000 sec 1, preferably greater
than about 15,000 sec, most preferably greater than 30,000
2Q sec 1. The clay, on the other hand, should preferably be added
last to minimize excessive exposure to shear in product. Each of
these preferred processing steps gives compositions with superior
stability. The gas can also be introduced in finely divided form
by using a sparger.
25 The Suspended Particles
The particles herein can be any of the materials which are
conventionally suspended in aqueous liquids. The particles can
be insoluble abrasive part1cles, soluble inorganic materials such as
detergent builder materials that are present in excess of their
30 solubility in the aqueous liquid, soluble materials which are made
Insoluble by coating with insoluble material, etc. The invention
is especially desirable for use in the preferred compositions
described hereinafter.
The solid suspended material comprises from about 0% to
35 about 50% of the composition, preferably from about 3% to about
40% of the composition, most preferably from about 5% to about
Z~5~
30% of the composition. The benefits of the invention are readily
seen when the solid particles have a specific gravity which is
about 1096, especially 50%, more especially 100% Ir,ore, than the
- specific gravity of the aqueous liquid.
5 Optional Ingredients
Detergent Surfactants
The co~.positions of this invention can contain frorr, 0% to
about 40%, preferably fror~, about 20% to about 30%, or Ir.ore
preferably frorr, about 0 . 2% to about 5% of detergent surfactant
10 based upon the desired end use. The choice of detergent
surfactant and amount will depend upon the end use of the
product. For example, for an autorr.atic dishwashing product the
level of surfactant should be less than about 5%, preferably less
than about 3%, and the detergent surfactant should be low
15 sudsing. Desirable detergent surfactants include nonionic deter-
gent surfactants, anionic detergent. surfactants, am.photeric and
- ~ zwitterionic detergent surfactants, and mixtures thereof.
- Examples of nonionic surfactants include:
(1 ) the condensation product of 1 Ir~le of a saturated or
20 unsaturated, straight or branched chain, alcohol or fatty acid
containing fro~. about 10 to about 20 carbon atoms with from.
about 4 to about 50 rr,oles of ethylene oxide. Specific examples of
such compounds include a condensation product of 1 mole of
coconut fatty acid or tallow fatty acid with 10 moles of ethylene
25 oxide; the condensation of 1 mole of oleic acid with 9 Ir.oles of
ethylene oxide; the condensation product of 1 rr,ole of stearic acid
with 25 moles of ethylene oxide; the condensation product of 1
mole of tallow fatty alcohols with about 9 Irloles of ethylene oxide;
the condensation product of 1 mole of oleyl alcohol with 10 moles
30 of ethylene oxide; the condensation product of 1 Ir.ole of Cl g
alcohol and 8 Ir,oles of ethylene oxide; and the condensation
product of one Irlole of C18 alcohol and 9 moles of ethylene oxide.
The condensation product of a fatty alcohol containing from
17 to 19 carbon atoms, with frorr~ about 6 to about 15 moles,
35 preferably 7 to 12 moles, most preferably 9 moles, of ethylene
lZ9Z657
oxide provides superior S/F performance. More partlcularly, it Is
deslrable that the fatty alcoho! contain 18 carbon atoms and be
condensed with from about 7.5 to about 12, preferably about 9,
moles of ethylene oxide. These various specific C17-C19
5 ethoxylates give extremely good performance even at lower levels
(e.g., 2.596-3%) and at the higher levels 1>5%) are sufficiently low
sudsing, especially when capped with a low molecular weight
(Cl 51 acid or alcohol moiety, so as to minimize or eliminate the
need for a suds-suppressing agent. Suds-suppressing agents in
10 general tend to act as a load on the composition and to hurt long
term S/F characteristics.
(2) Polyethylene glycols having molecular weight of from
about 1,400 to about 30,000, e.g., 20,000; 9,500; 7,500; 6,000;
4,500; 3,400; and 1,450. All of these materials are waxlike solids
15 which melt between 110F. and 200F.
(3) The $ondensation products of 1 mole of alkyl phenol
wherein the alkyl-chain~contains from about 8 to about 1O carbon
atoms and from about 4 to about 50 moles of ethylene oxide.
Speclflc examples of these nonionics are the condensation products
20 of 1 mole of decylphenol with 40 moles of ethylene oxide; the
condensatlon product of 1 mole of dodecyl phenol with 3S moles of
ethylene oxlde; the condensation product of 1 mole of
tetradecylphenol with 25 moles of ethylene oxide; the condensatlon
product of 1 mole of hectadecylphenol with 30 moles of ethylene
25 oxide, etc.
(4) Polyoxypropylene, polyoxyethylene condensates having
the formula HO(C2H4O)x(C3H6O)y (C2H4O)XH where y equals at
least 15 and (C2H4O)(x + x) equals 20% to 90% of the total weight
of the compound and the molecular welght is from about 2,000 to
30 about 10,000, preferably from about 3,000 to about 6,000. These
materlals are, for example, the Pluronlcs whlch are well known in
the art.
(5) The compounds of (1) whlch are capped with propylene
oxlde, butylene oxide and/or short chain alcohols andior short
.
;:
. ~
lZ9Z657
- 10 -
chain fatty acids, e.g., those containing from 1 to about 5 carbon
atoms, and mixtures thereof.
Preferred surfactants are those having the formula
RO-(C2H40)XR1 wherein R is an alkyl or alkylene group contain-
5 Ing from 17 to 19 carbon atoms, x is a number from about 6 toabout 15, preferably from about 7 to about 12, and R1 15 selected
from the group consisting of: preferably, hydrogen, C1 5 alkyl
groups, C2 5 acyl groups and groups having the formula
-(CyH2yO)nH wherein y is 3 or 4 and n is a number from one to
10 about 4.
Also preferred are the low sudsing compounds of (4), the
other compounds of (5), and the C17_19 materials of (1 ) which
have a narrow ethoxy distrlbutlon.
In addition to the above mentioned surfactants, other suit-
15 able surfactants can be found in the dlsclosures of U. S. PatentNos. 3,544,473, 3,630,923, 3,888,78t and 4,001,132.
When the composition contains a hypochlorite bleach it is
preferable that the detergent surfactant is bleach stable. Such
20~ surfactants desirably contain no functions, such as unsaturation,
some aromatic structures, amide, aldehydic, methyl keto or
hydroxyl groups which are susceptible to o~idation by the
hypochlorite,
Bleach-stable surfactants which are especially resistant to
25 hypochlorite oxidation fall Into two maln groups. One such class
; of bleach-stable surfactants are the water-soluble alkyl sulfates
and/or sulfonates, containlng from about 8 to ~18 carbon atoms in
the alkyl group. Alkyl sulfates are the water-soluble salts of
sulfated fatty alcohols. They are produced from natural or
synthetic fatty alcohols contalnlng from about 8 to 18 carbon
atoms. Natural fatty alcohols include those produced by reducing
; ~ the glycerldes of naturally occurring fats and oils. Fatty alcohols
can be produced synthetically, for example, by the Oxo process.
Examples of suitable alcohols which can be employed In alkyl
3s sulfate manufacture Include decyl, lauryl, myristyl. palmityl and
" - ~
:,,
:: :
.
12SZ657
stearyl alcohols and the mixtures of fatty alcohols derived by
reducing the glycerides of tallow and coconut oil.
Specific examples of alkyl sulfate salts which can be em-
ployed in the instant detergent compositions include sodium lauryl
alkyl sulfate, sodium stearyl alkyl sulfate, sodium palmityl alkyl
sulfate, sodium decyi sulfate, sodium myristly alkyl sulfate,
potassium lauryl alkyl sulfate, potassium stearyl alkyl sulfate,
potassium decyl sulfate, potassium palmityl alkyl sulfate,
potassium myristyl alkyl sulfate, sodium dodecyl suflate,
potassium dodecyl sulfate, potassium tallow alkyl sulfate, sodium
tallow alkyl sulfate, sodium coconut alkyl sulfate, magnesium
coconut alkyl sulfate, calcium coconut alkyl sulfate, potassium
coconut alkyl sulfate and mixtures of these surfactants. Highly
preferred alkyl sulfates are sodium coconut alkyl sulfate,
potassium coconut alkyl sulfate, potassium lauryl alkyl sulfate and
sodium lauryl alkyl sulfate.
A second class of bleach-stable surfactant materials operable
in the instant invention are the water-soluble betaine surfactants.
- These materials have the general formula:
R
R - N~+) - R4 - COOl-~
wherein Rl ls an alkyl group containing from about & to 18 car-
bon atoms; R2 and R3 are each lower alkyl groups containing
from about 1 to 4 carbon atoms, and R4 is an alkylene group
selected from the group consisting of methylene, propylene,
butylene and pentylene . l Propionate betaines decompose in
aqueous solution and hence are not included in the instant compo-
sitions) .
Examples of suitable betaine compounds of this type include
dodecyldimethylammonium acetate, tetradecyldimethylammonium
acetate, hexadecyldimethylammonium acetate, alkyldimethyl-
ammonium acetate wherein the alkyl group averages about 14.8
carbon atoms in length, dodecyldimethylammonium butanoate,
tetradecyldimethylammonium butanoate, hexadecyldimethylammonium
129Z657
butanoate, dodecyldimethylammonium hexanoate,
hexadecyldimethylammonium hexanoate, tetradecyldiethylammonlum
pentanotate and tetradecyldipropyl ammonium pentanoate.
Especially preferred betaine surfactants include
5 dodecyldimethylammonium acetate, dodecyldimethylammonium
hexanoate, hexadecyldimethylammonium acetate, and
hexadecyldimethylammonium hexanoate,
Other desirable bleach stable surfactants are the alkyl
phosphonates, taught in U . S . Patent 4 ,105, 573, of Ronald L.
Still other preferred bleach stable surfactants and compositions
containing said sur~actants including Dowfax 3B2 and similar surfactants are
disclosed in published U.K. Patent Applications 2,163,447A, published
February 26, 1986; 2,163,448A, published February 26, 1986; and 2,164,350A,
15 published March 19, 1986.
Bleaching Agent
The instant compositions optionally and desirably include a
bleaching agent. Any suitable bleaching agent and especially
those that yield active chlorine or active oxygen in aqueous
20 solution can be employed.
A highly preferred bleaching agent is one which yields a
hypochlorite species in aqueous solution. The hypochlorite ion is
chemically represented by the formula OCI . The hypochlorite ion
is a strong oxidizing agent and for thls reason materials which
25 yleld this species are considered to be powerful bleaching agents.
The strength of an aqueous solution containing hypochlorite
lon Is measured in terms of available chlorine. This is the ox-
ldlzing power of the solution measured by the ability of the
solution to liberate iodine from an acldified iodide solution. One
30 hypochlorite ion has the oxidizing power of 2 atoms of chlorine,
i.e. one molecule of chlorine gas.
At lower pH levels, aqueous solutions formed by dissolving
hypochlorlte-yielding compounds contain active chlorine partially
In the form of hypochlorous acid moieties and partially in the form
35 of hypochlorite ions. At pH levels above about 10, i.e., at the
, ..
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- 13 -
preferred pH levels of the instant compositions, essentially all of
the active chlorine is in the form of hypochlorite ion.
Those bleaching agents which yield a hypochlorite species in
aqueous solution include alkali metal and alkaline earth metal
5 hypochlorites, hypochlorite addition products, chloramines,
chlorimines, chloramides, and chlorimides. Specific examples of
compounds of this type include sodium hypochlorite, potassium
hypochlorite, monobasic calcium hypochlorite, dibasic magnesium
hypochlorite, chlorinated trisodium phosphate dodecahydrate,
10 potassium dichloroisocyanurate, sodium dichloroisocyanurate,
sodium dichloroisocyanurate dihydrate, trichlorocyanuric acid,
1,3-dichloro-5,5-dimethylhydantoin, N-chlorosulfamide, Chloramine
T, Dichloramine T, Chloramine B and Dichloramine B. A pre-
ferred bleaching agent for use in the compositions of the instant
15 invention is sodium hypochlorite.
Most of the above-described hypochlorite-yielding bleaching
agents are available in solid or concentrated - form and are dis-
solved in water during preparation of the compositions of the in-
stant invention. Some of the above materials are available as
20 aqueous solutions.
If present, the above-described bleaching agents are dis-
solved in the aqueous liquid component used to form the false
body fluid phase. Bleaching agents can provide from about 0.1%
to 10~ available chlorine by weight, preferably from about 0.5% to
25 2.0% available chlorine by weight, of the total composition.
Buffering Agent
Especially when the instant compositions contain such
optional ingredients as bleach and surfactant, it is generally
desirable to also include one or more buffering agents capable of
30 malntaining the pH of the instant compositions within the alkaline
range. It is in this pH range that optimum performance of the
bleach and surfactant are realized, and it is also within this pH
range wherein optimum composition chemical stability is achieved.
When the essential thickening agent is a clay material and
35 when a hypochlorite bleach is optionally included in the instant
129Z65~
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compositions maintenance of the composition pH within the 10.5 to
12 . 5 range minimizes undesirable chemical decomposition of the
active chlorine, hypochlorite-yielding bleaching agents, said
decomposition generally being encountered when such bleachlng
5 agents are admixed with clay in unbuffered aqueous solution.
Maintenance of this particular pH range also minimizes the
chemical interaction between the strong hypochlorite bleach and
the surfactant compounds optionally present in the lnstant
compositions. Finally, as noted, high pH values such as those
10 maintained by an optional buffering agent serve to enhance the
soil and stain removal properties of the surfactant during
utilization of the present compositions.
Any compatible material or mixture of materials which has the
effect of maintaining composition pH within the alkaline pH range,
and preferably within the 10.5 to 12.5 range, can be utilized as
the optional buffering agent in the instant invention. Such
- - materials can include, for example, various water-soluble, inor-
- ganic -salts such as the carbonates, bicarbonates,
sesquicarbonates, silicates, pyrophosphates, phosphates,
20 tetraborates, and mixtures thereof. Example of materials which
can be used either alone or in combination as the buffering agent
herein include sodium carbonate, sodium bicarbonate, potassium
carbonate, sodium sesquicarbonate, sodium silicate, tetrapotassium
pyrophosphate, tripotassium phosphate, trisodium phosphate,
25 anhydrous sodium tetraborate, sodium tetraborate pentahydrate
and sodium tetraborate decahydrate. Preferred buffering agents
for use herein include mixtures of tetrapotassium pyrophosphate
and trisodium phosphate in a pyrophosphate/phosphate weight
ratio of about 3:1, mixtures of tetrapotassium pyrophosphate and
30 tripotassium phosphate in a pyrophosphate/phosphate weight ratio
of about 3:1, and mixtures of anhydrous sodium carbonate and
sodium silicate in a carbonate/metasilicate weight ratio of about
3:1 .
As discussed hereinbefore and hereinafter, it is also highly
35 preferred to include in the instant compositions a material which
129Z657
acts as a detergency builder, i.e. a material which reduces the
free calciun and/or magnesium ion concentration in a
surfactant containing aqueous solution. Some of the
above-described buffering agent materials additionally serve as
builder materials. Such compounds as the alkali metal carbonates,
phosphates, tripolyphosphates and pyrophosphates are of this
type. Other buffering agent components such as the silicates and
tetraborates perform no appreciable calcium control function.
Since presence of a builder in the instant compositions is
highly desirable, it is preferred that the optional buffering agent
contain at least one compound capable of additionally acting as a
builder, i.e. capable of lowering the free calcium and/or magne-
sium ion content of an aqueous solution containing such ions.
If present, the above-described buffering agent materials are
dissolved in the aqueous liquid component. Buffering agents can
generally comprise from about 2% to 15% by weight, preferably
from about 5% to 8% by weight, of the total composition.
Other Optional Materials
-
In addition to the above-described bleach, surfactant and
buffering agent optional components, the instant compositions can
contain other non-essential materials to enhance their
performance, stability, or aesthetic appeal. Such materials in-
clude optional nonbuffering builder compounds, coloring agents
and perfumes. Although, as noted above, some of the
above-described buffering agents can function as builder com-
pounds, it is possible to add other builder compounds which
either alone or in combination with other salts do not buffer
within the preferred pH rans3e. Typical of these optional builder
compounds which do not necessarily buffer within the highly
preferred 10. S-12 . 5 pH range are certain hexametaphosphates and
polyphosphates. Specific examples of such optional builder mate-
rials include sodium tripolyphosphate, potassium tripolyphosphate
and potassium hexametaphosphate.
Conventional coloring agents and perfumes can also be added
to the instant composTtions to enhance their aesthetic appeal
l;~9Z657
- 16 -
and/or consumer acceptability. These materials should, of
course, be those dye and perfume varieties which are especially
stable against degradation by strong active chlorine bleaching
agents if such bleaching agents are also present.
If present, the above-described other optional materials
generally comprise no more than about 35~ by weight of the total
composition and are dissolved, suspended or emulsified in the
aqueous liquid component used to form the false body fluid phase
of the instant compositions.
Preferred Composition
Preferred compositions of this invention are liquid automatic
dishwasher compositions comprising:
l1 ) from about 0% to about 5%, preferably from about 0.2%
to about 2% of a bleach-stable low foaming detergent
1 5 surfactant;
(2) from about 10% to about 40%, preferably from about 20%
- ~ to about 30% of 3 detergency builder, especially
builders selected from the group consisting of sodium
- tripolyphosphate, sodium carbonate, a potassium
pyrophosphate, and mixtures thereof;
(3) a hypochlorite bleach to yield available chlorine in an
amount of from about 0 . 3% to about 2. 5%, preferably
from about 0.5% to about 1,5%;
(4) from about 0.1% to about 10%, preferably from about
0.5% to about 5% of a clay thickening agent; and
(5) the balance a continuous phase of aqueous liquid, said
composition having:
(a) a yield value of from about 20 to about 500
dynes/cm2, preferably from about 100 to about 300
dynes/cm2;
(b) from about 10% to about 40%, preferably from about
15% to about 30% of said detergency builder,
preferably sodium tripolyphosphate, in the form of
undissolved particles having a particle size range
of from about 2 microns to about 500 microns,
preferably from about 10 microns to about 100
microns; and
- 129Z6~'7
- 17 -
(c) from about 19~ to about 20%, preferably from about
5~ to about 15% of entrained gas bubbles having a
maximum diameter of less than about 1/8'1, said gas
preferably being selected from the group
consisting of air, nitrogen, CO2, 2' and He in an
amount to adjust the overall specific gravity of the
composition to within from about 596 more than to
from about 1096 less than, preferably within
from about 1~ more than to about 5% less than the
specific gravity of the aqueous liquid by itself.
The separation that occurs in these preferred compositions
without the gas is a separate liquid phase, unlike the prior art
compositions where the solids separated. Accordingly, it is
surprising that the gas also minimizeslstops the separation of the
liquid. It is surprising that within certain very critical limits
that gas is so very effective.
The Process For Preparation
Simple mixing procedures are used to prepare the
compositions of this invention. However, order of addition is
important and the degree of mixing is also important, As stated
hereinbefore, the gas can be admixed, e.g., by use of high
shear mixing, i.e., with shear rates greater than about 1000
sec 1, preferably g reater than about 15, 000 sec 1 . The clay, on
the other hand, should be added last with only enough low shear
mixing to ensure homogeneity. Each of these preferred process-
ing steps gives compositions with superior stability.
All parts, percentages and ratios herein are by weight
unless otherwise specified.
EXAMPLES
In all of the following examples, the composition was as
follows:
%
Sodium trlpolyphosphate (anhydrous basis) 23.4
Sodium silicate (2.4R) 7.0
35 Sodium carbonate 6.0
129Z6~7
-- 18 --
Available chlorine from sodium hypochlorite 1.4
` ~ Clay (Volclay HPM-20) ~1.0 (~20%)
Sodium Hydroxide ~0.7
Monostearyl Acid Phosphate ~0 03
S Anionic Surfactant (Dowfax 3B2) ~0.4
Minor Ingredients and Water Balance
In the following examples air was mixed in to give the
indicated initial specific gravities and the product was stored for
six weeks at the indicated temperatures. The aqueous portion of
10 the products had a specific gravity of about 1.27. The amount of
separated product at the top Is given in milliliters per slxty
ounces 60 oz. = 1.7 kilograms (Ml. per 60 oz. ) of product
although some of the samples were different si es as indicated.
Ml. of Separation/
Sample Product 60 oz. of product
Example SizeSpecific Gravity 70F 100F 120F
- 1 * 60 1.35 157205 235
2* 60 1.37 155188 255
3* 60 1.34 125168 212
20 4* 601 O 37 158192 278
5* 60 1.33 105155 202
6 60 1.26 <5 62 18
7 60 1.15 0 o 0
8 60 1.28 65 62 150
9 60 1.25 28 72 45
10* 60 1.32 110130 242
11 60 1.28 25 90 132
12 60 1.28 32 58 120
13 60 1.30 62 98 187
30 14* 40 1.32 135158 195
40 1.28 45 68 123
16* 40 1.33 90 135 150
- 17* 40 1.35 150195 240
18* 40 1.33 135158 195
35 19* 40 1.33 135172.5 218
1~9;~657
- 19 -
1.29 75 135 195
21 * 40 1.33 150190 240
2~* 60 1.31 140175 235
23* 63 1.34 150210 267
24* 60 1,32 85 122 165
1.29 70 115 155
26 60 1.28 55 135 192
27 60 1.30 45 100 160
28 60 1.29 30 78 150
29* 60 1.32 110118 230
30* 80 1.32 112150
31 80 1.30 9~ 84 185
32 80 1.29 66 79 155
33* 80 1.33 90 135 214
34* 80 1.31 75 94 178
1.28 <5 28 60
- 36* 80 1-.32 54~109 158
- 37 80 1.26 <5 <5 82
38* 80 1.31 46 112 189
39 80 1.27 8 8 <S
1.27 <5 <5
41 80 1.26 <5 11 41
42 80 1.25 0 8 8
43 60 1.25 0 <5 <5
44 60 1.27 10 60 7
1.26 <5 8 <5
46 80 1.26 19 9 13
47 80 1.22 0 0 5
48** 80 1.26 <5 15 130
49* 80 1.31 160175 278
*Comparatlve Examples
**Separatlng crystals, indicatlng solids formed after preparation
of the suspension.
WHAT IS CEAIMED IS:
