Note: Descriptions are shown in the official language in which they were submitted.
~7'Q~.~Z
-P-IR838-F
THIXOTROPIC LIQUI~ AUTOMATIC DISHWASHER DETERGENT
COMPOSITION WITH IMPROVED PHYSICAL STAB~LITY
The present invention relates to automatic dishwashing
detergent compositions having thixotropic properties, improved
chemical and physical stability, and which are readily
dispersible in the washing medium to provide effective
cleaning of dishware, glassware, china and the like.
Commercially available household-machine dishwasher
detergents provided in powder form have several disadvantages,
e.g. non-uniform composition; costly operations necessary in
their manufacture; tendency to cake in storage at high humidities
resulting in the formation of lumps which are difficult
to disperse; dustiness, a source of particular irritation
to users who suffer allergies; and tendency to cake in the
dishwasher machine dispenser. Liquid forms of such compositions,
moreover, generally cannot be used in automatic dishwashers
due to high foam levels, unacceptably low viscosi~ies and
exceedingly high alkalinity.
Recent research and development activity has focussed
on ~he gel or "thixotropic" form of such compositions, e.g.
scouring cleansers and automatic-dishwasher products characterize
as thixotropic pastes. Dishwasher products so provided
sre primarily objectionable in that they are insufficien~ly
viscous to remain "anchored" in the dispenser cup of the
dishwasher, and moreover yield spot~y residues OD dishware,
glassware, ch:ina and the like. Ideally, thixotropic cleansing
compositions should be highly viscous in 8 quiescent state,
Bingham plastic in nature, and have relatively high yield
values. When subjected to shear s~resses, however, such
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~ ~;27~'7~
as being shaken in a container or squeezed through an orifice,
they should quickly fluidize and, upon cessation of the
applied shear stress, quickly revert to the high viscosity/
Bingham plastic state. Stability is likewise of primary
importance, i.e. there should be no significant evidence
of phase separation or leaking after long standing.
The provision of automatic-dishwasher compositions
in gel form having the aforedescribed properties has thus
far proven problematical, particularly as regards compositions
for use in home dishwasher machines. For effective use,
it isgenerally recommended that the automatic dishwashing
detergent, hereinafter also designated ADD, contain (1)
sodium tripolyphosphate (NaTPP) to soEten or tie up hard-water
minerals and to emulsify and/or peptize soil; (2) sodium
silicate to supply the alkalinity necessary for effective
detergency and to provide protec~ion for fine china gla~e
and pattern; (33 sodium carbona~e, generally considered
to be optional, to enhance alkalinity; (4) a chlorine-releasing
agent to aid in the elimination of soil specks which lead
to water spotting; and (5) defoamer/surfactant to reduce
foam, thereby enhancing machine efficiency and supplying
requisite detergency. See, for example, SDA Detergents
in Depth, "Formulations Aspects of Machine Dishwashing,"
Thomas Oberle (1974~. Cleansers approximatin~ ~o the afore-
described compositions are mostly liquids or powders. Combi~ing
such ingredients in a gel form e~fective for home-machine
use has proved difficult. Generally, such compositions
omit hypochlorite bleach, since it tends to react with other
chemically active ingredients, particularly surfactan~,
thereby degrading the suspending or thixotropic agent and
11 ~?~7~
.' ~
impairing its effectiveness. Thus, U.S. Patent 4,115,308
discloses thixotropic automatic dishwasher pastes eontaining
a suspending agent, e.g. CMC, synthetic clays or the like;
inorganic salts including silicates, phosphates and poly-
phosphates; a small amount of surfactant and a suds depressor.
Bleach is not disclosed. U.S. Patent No. 4, 147,650 is
s~mewhat similar, optionally including Cl-(hypochlorite)
bleach but no organic surfactant or foam depressant. The
product is described, moreover, as a de~ergent slurry with
no apparent thixotropic properties.
U.S. Patent NoO 3,985,668 describes abrasive scouring
cleaners of gel-like consistency containing (1) suspending
agent, preferably the Smectite and attapulgite types of
clay; (2) abrasive, e.g. silica sand or perlite; and (3)
filler comprising light density powdered polymers, expanded
perlite and the like, which has a b,o~u`yancy and thus stabiliziDg
effect on the composition in addition to serving as a bul~ing
agent, thereby replacing water otherwise available for undesired
supernatant layer formation due to leaking and phase destabilizat on
The foregoing are the essential ingredients. Optional ingredient
include hypochlorite bleach, bleach stable surfactant and
buffer, e.g. silicates, carbonates, and monophosphates.
Builders, such as NaTPP, can be included as further optional
ingredients to supply or supplement building function not
prov;ded by the buffer, the amoun~ of such builder not exceeding
5% of the total composition, according to the patent. ~aintenanc
of the desired (greater than) pH 10 level~ is achieved by
the buffer/builder components. Hi~h pH is aid ~o minimize
decomposition of chlorine bleach and undesired interaction
between surfaetant and bleach. When present, NaTPP is limited
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to 5%, as stated. Foam killer is not disclosed.
Tn U.K. Patent Application GB 2,116,199A and
GB 2,140,450A, both of which are assigned to Colgate-Palmolive,
liquid ADD co~positions are disclosed which have properties
desirably characterizing thixotropic, gel-type structure
and which include each of the various ingredients necessary
for effective detergency with an automatic dishwagher.
The normally gel-like aqueous automatic dishwasher detergent
composition having thixotropic properties includes the following
ingredients, on a wei~ht basis:
(a) 5 to 3% alkali metal tripolyphosphate;
(b) 2.5 to 20% sodium silicate;
(c) 0 to 9% alkali metal carbonate;
(d) 0.1 to 5% chlorine bleach stable, water dispersible
organic detergent active material;
(e) 0 to 5% chlorine bleach stable foam depressant;
(f) chlorine bleach compound in an amount to provide
about 0.2 to 4% of available chlorine; and
(g) thixotropic thickener in an amount sufficient
to provide the c~mposition with thixotropy index of about
2.5 to 1~.
ADD compositions so formulated are low-foaming;
are readily soluble in the was~ing medium and most effective
at pH values best conductive ~o improved cleaning performance,
viz, pH 10.S-13.5. The compositions are normally o gel '
consistency, i.e. a highly viscous, opaque jelly-like material
having Bingham plastic character and thus rela~ively high
yi~ld values. Accordingly, a definite shear force i5 necessary
to initiate or increase flow, such as would obtain within
the agitated dispenser cup of an energized automatic dishwasher.
l ~Z7~
Under such conditions, the composition is quickly fluidized
and easily dispersed. When the shear force is discontinued,
the fluid composition quickly reverts to a high viscosity,
Bingham plastic state closely approximateing its prior con-
sistency.
While these previously disclosed liquid ADD formulation
are not subject or subject to a lesser degree to one or
more of the above described deficiencies, i~ has been found
that in actual practice, still further improvements in physical
stability are required to increase the shelf-like of the
product and thereby enhance consumer acceptance.
Accordingly, it is an object of ~he invention
to provide liquid ADD compositions having thixotropic properties
with improved physical stability and rheological properties.
It is also an obiect of the invention to provide
thixotropic liquid ADD compositions having reduced levels
of thixotropic thickener without adversely effecting the
generally high viscosities at low shear reates and lower
viscosities at high shear rates which are characteristic
of the desired thixotropic properties.
These and other objects of the invention which
will become more readily understood from the following detailed
description of the invention and preferred embodiments thereof
are achieved by incorporating in a normally gel-like aqueous
automatic dishwasher detergent composition an amount of
a polyvalent metal salt of a long chain fatty acid which
is effective to inhibit settling of the suspended part~cles,
such as thixotropic agent.
Accordingly, in one broad aspect, the present
invention provides a normally gel-like aqueous automati~
.
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dishwasher detergent composition having thixotropic properties
which include, on a weight basis:
(a) 5 to 35% alkali metal tripolyphosphate;
~b) 2.5 to 20% sodium silica~e;
(c) 0 to 9% alkali metal carbonate;
(d) 0.1 to 5~/O chlorine bleach stable, water dispersible
organic detergent active material;
(e) 0 to 5% chlorine bleach stable foam depressant;
(f) chlorine bleach compound in an amount to provide
about 0.2 to 4% of available chlorine;
(g~ thixotropic thickener in an amount suficient
to provide the composition with a thixotropy index of about
2.0 to 10;
(h~ 0 to 3% sodium hydroxide;
(i) a polyvalent metal salt of a long chain fatty
acid in an amount effective to increase the physical stability
of the composition; and
(j~ balance water.
In another aspect the invention provides a method
for cleaning dishwar~ in an automatic dishwashing machine
with an aqueous wash/bath containing an effective amoun~
of the liquid automatic dishwasher deterent (LADD) composition
as described above. According to tlis aspect o~ the invention,
the LADD composition can be readily poured into the dispensing
cup of the automatic dishwashing machine and will, within
just a few seconds 9 promptly thicken to its normal gel-like
state to remain securely within the dispensin~ cup until
shear forces are again applied the1reto, such 8S by the wster
spray from the dishwash;ng machine.
.
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Generally, ADD effectiveness is directly related
to (a) available chlorine levels; (b) alkalinityi (c) solubility
in washing medium; and (d) foam inhibition. It is preferred
herein that the pH of the ADD composition be at least about
9.5, more preferably from about 10.5 to 13.5 and most preferably
at least about 11.5. At relatively lower pH values, the
ADD product is too viscous, i.e. solid-like, and thus not
readily fluidized under the shear-force levels created within
the dispenser cup under normal machine operating conditions.
In essence, the composition loses much, if not all, of its
thixotropic character. Addition of NaOH is thus often needed
to increase the pH to within the above ranges, and to increase
flowability properties. The presence of carbona~e is also
often needed herein, since it acts as a buffer helping to
lS maintain the desired pH level. Excess cabonate is to be
avoided, however, since it may eause the formation of needle-like
crystals of carbonate, thereby impairin~ the stability,
thixotrophy and/or detergency of the ADD product. Caustic
soda (NaOH) serves the further function of neutralizing
the phosphoric or phosphonic acid ester foam depressant
when present. About 0.5 to 3wt% of NaOH and about ? to
9wt% of sodium carbonate in the composition are present.-
About 0.5 to 3wt% of NaOH and about 2 to 9w~% of sodium
carbonate in the composition are typical although it should
be noted that sufficient alkalinity may be provided by the
NaTPP and sodium silicate.
The NaTPP employed in the composition in a range
of about 8 to 35 wt%, preferably about 20 to 30wt%9 should
preferably be free of heavy metal which tends to decompose
or inactivate the preferred sodium hypochlorite and other
chlorine bleac:h compounds. The NaTPP may have an average
I ~27~
¦ degree of hydration of less than about 1 or more than about
5 e.g. O to 2.7% byweight or at least 16.5% of water, including
¦ the stable hexahydrate wi~h a degree of hydration of 6 correspond ng
to about 18% by weight of water or more. Actually, humidificatio
to an average of about 0.3 to 1% water is highly effective,
serving i~ is thought to form seeds of the stable hexahydrate
which expedites hydration and solubilization of the remaining
NaTPP particles. On average, the NaTPP contains abou~ 5
to 15% by weight water, corresponding to an average degree
of hydration of about 1 to 5. If only the hexahydrate is
used, the de~ergent product is liquid and has little if
any thixotropic character. If only the anhydrous NaTPP
is used, the product is too thick and therefore unsuitab~e.
Effective compositions are obtained, for example, when using
a 0.5:1 to 2:1 weigh~ ratio of anhydrous to hexahydrated
NaTPP, values of about 1:1 bein8 particularly preferred.
Foam inhibition is important to increase dishwasher
machine efficiency and minimize destabilizing effects which
might occur due to the presence of excess foam within the
washer during use. Foam may be sufficiently reduced by
suitable selection of the ~ype and/or amount of detergent
active material, the main foam-producing component. The
degree of foam is also somwhat dependent on the hardne~s
of the wash water in the machine whereby suitable adjustment
of the proportions of NaTPP which has a water softening
effect may aid in providing the desired degree of foam inhibition
However, it is generally preferred ~o include a ehlorine
bleach stable foam depressant or inhibitor. Particularly
effective are the alkyl phosphonic acid esters of ~he formula
_~_
~ 17Z - ~
HO P R
OR
available for example from BASF--Wyandotte (PCUK-PAE), and
especially the alkyl acid phosphate esters of the formula
HO - P- - OR
available for example from Hooker (SAP) and Knapsack (LPKn-158),
in which one or both R groups in each type of ester may
represent independently a C12_~0 alkyl group. Mix~ures
of the two types, or any other chlorine bleach stable types,
or mixtures of mono- and di-esters of the same type, may
be employed. Especially preferred is a mixture of mono-
and di-C16_1g alkyl acid phosphate ester~ such as monostearyl/
distearyl acid phosphates 1.2/1 (Knapsack~. When employed,
proportions of 0.1 to 5wt~/o~ preferably about 0.1 to 0.5wt%,
of foam depressant in the composition is typical, the weight
ratio of detergent active component (d) to foam depressant
(e) generally ranging from about 10:1 to 1:1 and preferably
abou~ 4:1 to 1 1. Other defoamers which may be used include
for example the known silicone~.
Although any chlorine bleach compound may be employed
in the composi~ions of this invention, such as dichloro-
isocyanurat~, dichloro-dimethyl hydantoin, or chlorinated
TSP, alkali metal, e.g. po~tassium, lithium, magnesium and `
especially sodium, hypochlori~e is preferred. The composition
should contain sufficient chlorine bleach compound to provide
about 0.2 to 4.0% by weight of available chlorine~ as
_g_
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determined for example by acidification of 100 parts of
the composition with excess hydrochloric acid. A solution
containing about 0.2 to 4.0% by weight of sodium hypochlorite
contains or provides roughly the same percentage of available
chlorine. About 0.8 to 1.6% by weight of available chlorine
is especially preferred. For example, sodium hypochlorite (NaOCl
solution of ll of 13% available chlorine in amounts of
about 3 to 20%, preferably about: 7 to 12%, can be advantageously
l used.
¦ The sodium silicate, which provides alkalinity
and protection of hard surfaces such as fine china glaze
and pattern, is employed in an amount ranging from about
2.5 to 20 wt%, preferably about 5 to 15wt%, in the eomposition.
The sodium silicate is generally added in the form of an
aqueous solution, preferably having an Na2O:SiO2 ratio of
about 1:2.2 to 1:2.8. At this point, it should be mentioned
that most of the other components of ~hi~ composition, especially
NaOH, sodium hypochlorite, foam depressant and thixotropic
thickener, are also often added in the form of a preliminary
prepared aqueous dispersion or solution.
Detergent active material useful herein must be
stable in ~he presence of chlorine bleach, especially hypo-
chlorite bleach, and preferably comprise those of the organic
anionic, amine oxide, phosphine oxide, sulphoxide or betaine
water dispersible surfactant types, the firæt mentioned
anionics being most preferred. They are used in amou ~
ranging from about 0.1 to 5~/O preferably about 0.5 to 2.0%,
more preferab]y about 0.3 to 0.8%. Particularly preferred
surfactant~ hereint are the linear or branched alkali metal
mono- and~or cli-~Cg_l4) alkyl diphenyl oxide mono and/or
~70~ ~
¦ disulphates, commercially available for example as DOWFAX
¦ (Registered Trade Mark) 3B-2 and DOWFAX 2A-l. In general,
the paraffin sulphonates tend to impair, if not destroy
l thixotropy, having been found to unduly increase viscosity
causing severe shearing force problems. In addition, the
surfactant should be compatible with the other ingredients
of the composition. Other suitable surfactants include the
primary alkylsulphonates, alkylr,ulphonates, alkylarylsulphonate~
and sec.- alkylsulphates. Examples are sodium Clo-C1~ alkylsulph ~es
such as sodium dodecylsulpha~e and sodium ~allow alcoholsulphate;
sodium C1o-Clg alkanesulphonates such as sodiumhexadecyl-l~ulphon ~te
and sodium C12-Clg alkylbenzenesulphonates such as sodcium
dodecylbenzenesulphonates, The corresponding potassium
salts may also be employed.
As other suitable surfactants or detergents, the
amine oxide surfactants are typically of the structure
R2RlNO, in which each R represent a lower alkyl group, for
instance methyl, and Rl represents a long chain alkyl gr~up
having from 8 to 22 carbon atoms, for instance a lauryl,
myristyl, palmityl or cetyl group. Instead of an amine
oxide, a corresponding surfactant pho~phine oxide R2RlPO
or sulphoxide RRlSO can be employed. Betaine surfactants
are typically of the s~ructure R2RlN~R"COO- , in which each
R represents a lower alkylene group having from 1 to 5 carbon
atoms. Specific examples of ~hese surfactants are lauryl-
dimethylamine oxide, myristyldimethylamine oxide, the correspondi ~g
phosphine oxicles and sulphoxides, and the correspond}ng
betaines including dodecyldimethylammonium acetate, tetra-
decyldiethylammonium pentanoate, hexadecyldimethylammonium
hexanoate and the like. For biodegradability, the alkyl
groups in these surfactants should be linear, and such compounds
~ Z ~ ~ 7
are preferred.
Surfactan~s of the foregoin~ type, all well known
in the art, are described, for example, in U.S. Patents
3,985,668 and 4,271,030.
Thixotropic thickeners, i.e. thickeners or suspending
agents which provide an aque~us medium with thixotropic
properties, are known in the art and may be organic or inorganic
water soluble, waterdispersible or colloid-furming, and
monomeric or polymeric, and should of course be stable in
these compositions, e.g. stable to high alkalinity and chlorine
bleach compounds, such as sodium hypochlorite. Those especially
preferred generally comprise the inorganic, colloid-forming
clays of smec~ite and/or attapulgite types. These materials
were generally used in amounts of about 1.5 ~o lO,preferably
2 to 5 wt%, to confer the desired thixo~ropic properties
and Bingham plastic character in the assignee's prior disclosed
ADD formulation~ of the aforementioned GB 2,116,199A and
GB 2,140,450A. It is one of the advantages of the ADD formulatio s
of the pre6ent inven~ion that the desired thixotropic proper~ies
and Bingham plastic character can be obtained in the presencç
of the polyvalent metal salt fatty acid stabilizer~ with
lesser amounts of the thixotropic ~hickeners. For exampl~e,
amounts of the inorganic colloid-forming clays of the smectite
and/or attapulgite types in the range of from about 0.1
to 3~/O~ preferably 0.2 to 2.5%, especially 0.5 to 2.2%, are
generally suff;cient to achieve the desired thixotropic
properties and Bingham plastic character when used in combination
with the physic:al stabilizer.
Smect:ite clays include montmorillonite (bentoni~e),
hectorite, saponi~e, and the like. Materials of this type
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are available under trade names such as Thixogel (Registered
Trade Mark) No. 1 and Gelwhite tRegistered Trade Mark) GP, H, etc
from Georgia Kaolin Company (both being montmorillonites).
Attapulgite clays include the materials commercially available
under the trade name Attagel ~Registered Trade Mark), i.e.
Attagel 40, Attagel 50 and Attagel 150 from Engelhard Minerals
and Chemicals Corporation. Mixtures ofsmectite and attapulgite
types in weight ratios of 4:1 to 1:5 are also useful herein.
Thickening or suspending agents of the foregoing types sre
well known in the art, being described, for example, in
U.S. Patent No. 3,985,668 referred to above. Abrasives
or polishing agents should be avoided.
The amount of water contained in these compos;tions
should of course be neither so high as to produce unduly
low viscosity and fluidity, nor so low as to produce unduly
high viscosity and low flowability, thixotropic properties
in either case being diminished or destroyed. Such amount
is readily determined byroutine experimentation in any particular
instance, generally ranging frcm about 45 to 75 wt%, preferably
about 55 to 65 wt%. The water should also be preferably
deionized or softened.
So far, the description of the ADD produc~ exc~pt
as otherwise noted, comforms to the compositions 8S diselosed
in the aforementioned UK Patent Applications GB 2,116~199A
and GB 2,140,450A.
The ADD products of these prior disclosures exhibit
improv d rheological properties ~s evaluated by testing product
viscosity as a function of shear rate. The compositions
exhibited higher viscosi~y at a low shear rate and lower
viscosi~y at a high shear rate, the data indicating efficient
fluidization and gellation well within the shear rates extant
3~'7~
within the dishwasher machine. In practical terms, this
meant improved pouring and processing characteristics as
well as less leaking in the machine dispenser-cup, compared
to ~rior liquid or gel ADD products. For applied shear
rates corresponding to 3 to 30 rpm, viscosities (Brookfield)
correspondingly ranged from about 15,000 to 30,000 cps to
about 3000-5000 cps, as measured ,at room temperature by
means of a LVT Brookfield viscometer after 3 minutes using
a No. 4 spindle. A shear rate of 7.4 sec~l corresponds
to a spindle rpm of about 3. An approximate ten-fold increase
in shear rate produces a six- to seven-fold reduction in
viscosity. With prior ADD gels, the corresponding reduction
in viscosity was only about twn-fold. Moreover, with such
compositions, the initial viscosity taken at about 3 rpm was
only about 2500-2700 cps. The compositions of the assignee's
prior invention thus exhibi~ threshold 1uidizations at
lower shear rates and of significantly greater extent in
terms of incremental increases in shear rate versus incremental
decrease in viscosity. This property of the ADD produc~s of the
prior invention is summarized in terms of a thixo~ropic index (TI
which ls the ratio of the apparent viscosity at 3 rpm and at 30
rpm. The prior compositions have a TI of from 2.5 to 10. -
The ADD compositions tested exhibited subætantial and quick
return to prior quiescent state consistency when the shear
force was discontinued.
The present invention is based upon the discovery
that the physical stability, i.e. resistance to phase separation
settling, etc., of these prior liquid aqueous ADD composition~
can be significan~ly improved, without adversely affecting,
and in some cases, advantageously affecting, their rheological
properties, by adding to the composition a small but effective
amount of ~ polyvalent metal salt of a long chaiD fatty acid.
I ,~
As an example oE ~he improvement in rheolo~ic~l
propeties it has been found that the viscos,t~i`es at low shear
rates, e.g. at a spindle rpm of ab~ut 3, apparent viscos;ties
l may often be increased from two- to three-fold with the
¦ incorporation of as little as 0.2% or less of the fatty
acid metal salt stabilizer. At the same time, the physical
stability may be improved to such an extent that e~en after
six weeks or longer, over temperature ranges extending from
near freezing to 40C and more, the compositions containing
the metal salt stabilizers do not undergo any visible phase
separation.
The preferred long chain fatty acids are the higher
aliphatic fatty acids having from about 8 to about 22 carbon
atoms, more preferably from about 10 to 20 carbon stoms,
and especially preferably from abuu~ 12 to 18 carbon atom~,
inclusive of the carbon atom of the carboxyl group of the
fatty acid. The aliphatic radic.al may be saturated or unsaturated
and maybe straight or branched. Mixtures of fatty acids
may be used, such as those derived from natural sources>
such as tallow fatty acid, coco fatty acid, soya fatty acid,
etc. .
Thus, examples of the fatty acids from which the
polyvalent metal salt stabilizers can be formed include,
for example, decanoic acid, dodecan~ic acid, palmitic acid,
myristic acid, stearic acid, oleic acid, eicosanoic acid,
tallow fatty acid, coco f~tty acid, soya fatty acid, mixtures
of these acids, etc. Stearic acid, in view of both commercial
availability and results, is preferred.
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.~ 2
The preferred polyvalent metals are aluminum and
zinc, although other polyvalent metals, especially those
of Groups IIA, IIIA, IVA, VA, VA, VIIA, IIB, IIIB, IVB,
VB and VIII of the Periodic Table of the ElPments can also
be used. Specific examples of such other polyvalent metals
include Mg, Co, ~i, Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb,
Bi, etc. Pre~erably, the metal salts are used in their
higher oxidation states.
Many of these metal salts are commercially available.
For example, the aluminum salts are available in the triacid
form, e.g. aluminum stearate as aluminum tristearate,
Al(C17H3sCOO)3. The monoacid salts, e.g. aluminum monostearate,
Al(OH32(C17H3sCOO) and diacid salts, e.g. aluminum distearate,
Al(OH)(C17H35C)2, and mixtur~s of two or three of the
mono-, di- and tri-acid salts can be used for those metals,
e.g. Al, with valences of +3, and mixtures of the mono- and
di-acid salts can be used for those metals, e.g. Zn, with
valences of ~2. It is most preferred that the diacids of
the +2 vslent metals and the triacids of ~he ~3 valent metals,
and the tetraacids of the +4 valent metals, be used in predominan
amounts. For example, at least 30%, preferably at leas~
50%, especislly preferably from 80 to 100% of the total
metal salt be in the highest possible oxidation state, i.e.
each of the poss;ble valence sites is occupied by a fatty
acid residue.
The metal salts, as mentioned above, ase generally
commer~ally available but can be easi~y produced by, for
example, saponification of a fatty acid, e.gO animal fa~,
stearic acid, etc., or the corresponding fatty acid ester,
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. .
Y~
62301-1380
followed by treatment wi-th an hydroxide or oxide of the poly-
valent metal, Eor example, in the case of the aluminum salt,
with alum, alumina, etc.
Aluminum steara-te, i.e. aluminum tristearate, and
zinc stearate, i.e. zinc distearate, are the preferred poly
valent fatty acid salt stabilizers.
The amount of the fatty acid salt stabilizers to
achieve the desired enhancement of physical stability will
depend on such factors as the nature of the Eatty acid sal-t,
the nature and amount of the thixotropic agent, detergent
active compound, inorganic salts, especially TPP, other ADD
ingredients, as well as the anticipated storage and shipping
conditions.
Generally, however, amounts of the polyvalent metal
fatty acid salt stabilizing agents in -the range of from about
0.02 to 1%, preEerably from about 0.06 to 0.8%, especially
preferably from about 0.08 to 0.4%, provide -the long term
stability and absence of phase separation upon standing or
during transport at both low and elevated temperatures as
are required for a commercially acceptable product.
In particular preferred embodiments of the invention
the composition comprises from about 0.1 to 0.2% by weight of
the physical stabilizer and from about 0.5 to 2% by weight of
an inorganic, colloid-forming clay as the thixotropic thickener
or, in another embodiment, from about 0.3 -to 0.4% by weight of
the physical stabilizer and about 0.25% by weight of an in-
organic colloid--forming clay as the thixotropic thickener.
Accord:ing to one preferred method of making these
t B d 17 -
.~7~72
62301-1380l
compositions, one should dissolve or disperse first all the
inorganic sal-ts, i.e. carbonate (when employed), silicate and
tripolyphosphate, in the aqueous medium. Thickening agent is
added last. The foam depressor (when employed) is prelimi-
narily provided as an aqueous dispersion, as is the thicken-
ing agent. The foam depressant d:ispersion, caustic soda
(when employed) and inorganic salts are first mixed at eleva-
ted temperatures in aqueous solution (deionized water) and
thereafter cooled, using agitation throughout.
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~Z~ ,..
¦ Bleach, surfactant, fatty acid salt, stabilizer and thickener
¦ disp-:rsion at r~om temperature are thereafter added to the
¦ cooled (25-35C) solution. Excl~ding the chlorine bleach
l compound, total salt concentration (NaTPP, sodium silicate
¦ and carbonate) is generally about 20 to 50wt%, preferably
about 30 to 40wt% in the composition.
Other conventional ingredients may be included
in these compositions in small amounts generally less than
about 3 wt% such as perfume, hydrotropic agents such as
the sodium benzene, toluene, xylene and cumene sulphonates,
preservatives, dyestuffs and pigments and the like, all of course
being stable to chlori~e bleach compound and high alkali~i~y
(properties of all the componen~s). Especia'.ly preferred
for colouring are ~he ch]or;nated phthalocyanines and
polysulphides of alunl;nosilicate wh:;c~ provide, respectively,
pleasing green and blue tint~. TiO2 may be employed
for whitening or neutralizing off-shades.
The liquid ADD compositions of this invention
are readily employed in known manner for washing dishes,
other kitchen u~ensils and the like in an automatic
dish washer, provided with a suitable detergent dispenser,
in an aqueous wash bath containing an effec~ive amount
of the composition.
The inven~ion may be put into practice in various
ways and a number of specific emobdiment~ will be described
to illustrate the invention wi~h reference to the accompanying
example~.
All amount~ and proportions referred to herein
are by weight of the composition unless otherwise indicated.
-18-
7Z
Example 1
In order to demonstrate the effect of ~he metal
salt stabilizer liquid ADD formula~ions are prepared
with varying amounts of ~tabilizer and thixotropic thickener.
Initially ~he following ingredients are mixed in a Guis~i
mixer at 50-60C:
%
Deionized waSer 41.10+y-x
Caustic soda solu~ion
(50% NaOH) l.OO
Sodium carbonate,
anhydrous 5.00
Sodium silicate, 47.5%
solution of Na2:si2
ratio of 1:2.4 15.74
Sodium TPP (substantially
~nhydrous-i.e. 0-5%,
especially 3%, moisture~
(Thermphos NW) 12.00
Sodium TPP (hexahydrate3
(Thermphos N hexa) 12.00
The mixture is cooled a~ 25-30DC and sgitation
maintained throughout, and the followingingredients at room
temperature are added there~o: -
Sodium hypochlorite
solution (11% available
chlorine) 9.00
Monostearylphosphate 0.16
DOWFAX 3B-2 ~45% Na
monodecyl/didecyl diphenyl
oxide disulphonste-a~ueou
solution) 0.80
Al tristearate or Zn
distreate x
Gel Wh;te H 2.00-y
.
~27~ 7~
The m~nostearyl phosphace foam depressant and
Dowfax 3B2 detergent active compound are added to the mixture
just before the aluminum tristearate or zinc distearate
stabilizer or right before the Gel White H thickener.
Each of the resulting liquid ADD formulations
as shown in Table I are measured for density, C~R (Capillary
Drainage Rate), apparent viscosity at 3 and 30 rpm, and
physical stability (phase separation) on standing and in
a shipping test. The results are also shown in Table I.
From the data reported in Table I the following
conclusions are reached:
The incorporation of 0.2 % Al stearate in a 1.5%
or in a 1% Gel White H containing formula as well as the
incorporation of 0.1% Al stearate or of 0.1% Zinc stearate
in a 2% Gel White H containing formula leads ~o a simultaneous
increase of the physical stability and o the apparent viscosity
(Table I, runs l (control), 2, 3, 6, and 9.
The incorporation of 0.1% Al stearate in a lD/o
Gel White H ~ontaining formula, of 0.2% Al stearate in a
O.5% Gel White H containing formula, and of 0.3 or 0.4%
Al stearate in a 0.25% Gel White H containing ormula leads
to an increase of ~he physical s~ability without any drastic
viscosity increase ~Table II, runs 1 (control), 4, 7, 10
and ll).
~5 For ~he combination of 0.1% Al stearate and 0.5/O
Gel White H (Run 8) the apparent viscosi~y values remain
. acceptable bu~ no significant improvement in physical stability
is obtained.
-20-
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~L~71~
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Cl c~ ~_ ~ ~ ~ a~ ~
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O' ~ o J _ .~ U
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2-' - a .C:~
LLI Z ~ ~ ~ ~ Y
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T ~ ~ ~ ~ ~ O
1~-- ~ C!~ Q ~1
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O _ _ O r Z cn
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t_~ E -- _
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-23-
~7al~72
Note~ to Table I
(1) No. 1 filter paper (~hatman) having a 6.4 cm
circle traced therenn is laid on a flat glass plate,
10 cm x 10 cm. A plastic tube, 6.4 cm long, 3.4 cm diameter,
is placed in a standing position, centered on the circle.
The tube is filled with the sample liquid ADD composition
( after standing for one day~. The time needed for the
solvent to seep out of the tube and reach the traced
circle is measured. Time is measured on ~hree side6
of the circle and averaged. Faster times means that
the gel is not successfully retaining the solvent (water3
which can then leak into the filter paper. Times greater
than 5 minut~ks are considered good. Times between 4
and 5 minutes are consider~d unstable but acceptable.
(2) Measured with spindle 4 after 3 minutes
on 24 hour old~samples.
(3) In height.
(4) In weight.
(5~ At 4C, room tempera~ure (RT=20+2C),
35C and 43C in glass bottle.
~6) Liquid separation measured after 6 weeks and
3000 Km in a private c}r (in weight in a pla}ric bottle).-
-24-
~ 7
Example 2
Using the same composition and preparation method
as in Example 1 except that in place of Gel White H as the
thixotropic thickener, 2% of Attagel 50 (an attapulgite
clay) or 0.4% of Bentone EW (a specially processed Hectorite
clay) was used with (runs 2 and 4) or without (control runs
1 and 3) aluminum tristearate. The apparent ViSCOsitieS
and physical stabilities were measured in the same manner
as described for Example 1. The results sreshown in Table
II.
From the results shown in Table II it can be seen
that small amounts of aluminum stearate are equally effective
in increasing ~he physical stability of attapulgite ~lay
and hectorite clay based liquid thixotropic automatic dishwasher
detergent compositions.
-25-
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æ ~ '`'
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E~
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tO ~6 D ~ ~`J ~/ ~I
tO ;zicn _ _
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~1 ~ Z ~ ~ u~ r~ o
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V _ _ . -
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3 ~J C~ ~ C~l ~ .~
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tO ~ ~Y ~ ~ ~ ~ C
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O ~ ~ _UJ ~ -
o ~ ~ v~ .
S.l ~ ~ ~ ~ rl ~1 U~ C~l
Ç~ ~; ~ ~ ~D ~_
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IYC:
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C~ ~i t-6
__ _
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U~ C~ t~ C'~ t~) C~
C-- . . . .
E-~ ~t~O ~1 ,_1 r~l ~1 ~C
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O :~: O~ C~l ~ O 0 ~1
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a) ~ ~ ~ ~ ~ ro ' ' -' ~'
C 0 - O~rl 1 a~ ~13 ~ S:~-
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-~6-
~7~ 7~
. Example 3
This example shows that inorganic aluminum and
zinc salts, including A1203, ZnS04 and A12(S04)3 and the
monovalent metal fatty acid salts do no~ provide improved
physical stability to the liquid thixotropic ADD composition~.
Using the same formulation as in Run 6 of Example l 0.1%
of each of A1203, ZnS04, Al2(S04)3 and sodium steara~e was
used in place of 0.1% aluminum stearate. The reBults of
the measurements of apparent viscosity and physical stability
are shown in Table III.
-27-
~7~7
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c~ LLJ ~) ~ ~I) a~ al a
t:~3
0~ N Z no IU ~ ~
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V~ ~ O O O O
t~~ ~t ._ ._ ._ ._
cr~ o __ O ~ ~ ~ ~
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L~ Z ~n u
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_ O O l-- ~ O O _ ~ O O ~O O ~I ~ O
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I_ ~ l _ _ _ 11 _ n 11
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:SE ~ 3 ~ ~ q~ ~ ~U ~ ~11 ~ ~ ~ J
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N ~ ~ N _ In ql N ~ 1 C~ In a) N~ ~ v~
3: ~ C~ ~: ~ r ~ T 1~ C ~ T ~ C t!~ T ~i ~ C~
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o
-29-
Ex~mple 4
Th~ followin g~l-lik~ thlxotI~op~c liquid ADD i~
prepared followln~ th~ ~m~ ~gner~l procodure~ ~ In ~x~mple
1:
~LE~ ~''
Sodium ~llic~t~ (47.5% ~ol'n
~2~S1~2~1~2 . 4~ 7 . ~8
Mono~e~Rryl phoilphs~ O.16
Dowf~x ~-2 0 . 37
1~3rmphos N~ 12 . ~
Th~rmphos N h~a{~ 12 . O
Aluminum er~ ~t~ to 0 .1
SodluE~ Csrbons~ nhydrou~ 4.9
C~u3tic aod~ oolu~ion
(38-Xo N~OH~ 3 ~
Ph~rm~g~l Ex Uroelay
~Al Slli~t~ y3 1. 2S
Sodi-um bypochlor~to ~olutlon
~tor ~ nc~
p~ 12.g ~o 12.9
a~ or ~un~s o~ por~ , colo~, ~tc. csln ~l~o b~ 2t ~o
for~lult:ion .
~30_
