Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
3 ~
ll 62301-1408
,P-IRDIXIT THIXOTROPIC AQUEOUS SUSPENSIONS
The spplics~ion is relatPd to cc,mmo~ly assigned
Canadian application No. 511,518 fil.ed Jun~ l3 , 1986
in the names of Drapier, et ~l.
The pre~ent invention relates to thixotropic aqueous
suspension with improved physical 6tsbility. More ~pecifically
the invention relates to ~he use of lon~ chain f~tty scids
as ~ thixotropic agent for forming stab:Le gel-like liquid
~uspension~ ~uitsble for use as liquid ~utomatic dishwasher
detergent compo~ition.
The pre6ent invention ~pecifically relates to automatic
dishwashin~ deter~ent comp~sitions hsving thixotropic properties,
improved chemical and physicsl ~tability, and with increa~ed
~pparen~ viscos;ty, and which ~re resdily diepersible in
the w~shing medium to pro~ide effective cleaning of di~hware,
gla~sware, china and the like.
:Commerci~lly sv~ilable household-mschine di6hwasher
detergents provided in powder orm h~ve several dissdvantages,
: e.g. non-uniform compo5i~ion; eostly operations neces~ary
in their manufacture; tendency to cake in storage at high
humidities , resulting in the formation of lumps which
are difficult to disperse; dustine~s, ~source of particular
irritation to users who suffer sllergies; and tendency
¦ to cake in the dishwasher mschine dispens~r. Liquid forms
¦ of such compositions, however, generally cannot be used
¦ in automatic dishwashers due to hi~h foam levels, unacceptably
¦ low viscosities and exceedin~ly hi~h alkalinity.
: I Recent research and develop~ent activity has focused
on the ~el or "thixotropic" form of such compositions,
~ 3 ~
insufficiently viscous to remain "anchored" in the dispenser
cup of the dishwasher, and mo~eover yield spotty residues
on dishw re, glassware, china and the like. Ideally, thixo-
tropic clean~ing oompositions ~hould be highly vi~cous
in a quiescent state, Bingham plas~ic in na~ure, and have
relatively high yield value~. When 6ubjected to shear
6tresses, however, such ~s being ~haken in 8 container
or squeezed through an orifice, they should quickly fluidize
~nd, upon ces~ation of the applied shesr 6tre6~, quickly
revert to ~he hi~h vi~cosity/Bingham plastic st&te. Stability
i6 likewise of primary importance, i.e. there should be
no significant evidence of ph~se separation or leaking
~fter long ~tsnding.
The provi6ion of ~utomatic-dishwasher compositions
in gel form having the aforedescribed propertie~ has thus
far proven problematical, particularly as regards compositions
for use in home di6hw~sher machines. For effective use,
it is ~enerally recommended that the ~utomstic di~hwa~hing
detergent, hereinafter al~o designated ADD, co~tain (1~
odium tripolyphoæphste (NaTPP) to ~often or ~ie up hsrd-wzter
minerals ~nd to emul6ify and/or pep~ize 50il; (2) 60dium
silicate to 6upply the slkalinity nece~6ary for effective
detergency ~nd to provide protection for fine china glsze
and pattern; (33 sodium csrbonate, generally con6idered
to be optional, to enhance slkalinity; (4) a chlorine-releasing
agent to aid in the elimination of 60il specks which lead
to water spotting; snd (5) defoamer/surfactant to reduce
foam, thereby enhancing macbine efficiency ~nd 8upplying
requisite detergency. See, for example, SDA Detergents
in Depth, "Formulations Aspects of Machine Dishws~hing,"
Thomas Oberle (1974). Cleansers approximatin~ to the afore-
-2-
~ 3 ~
described compssitions are mostly liquids or powders. Combiningsuch ingredien~s in a gel form effective for home-machine
use has proved difficult. Generally, such eompositions
omit hypochlorite bleach, since it ~ends ~o resct with
other chemically active ingredients, particulsrly ~urf~ctant,
thereby degrading the suspending or ~hixotropic agent and
impairin~ its effectlveness. Thus, U.!,. Patent 4,115,308
discloses thixotropic automa~ic dishwasher pastes containing
8 fiuspending sgent, e.g. CMC, 6yn~hetic clays or the like;
inorganic salts including silicates, phosphstes nd polyphosphate ,;
a 6mall amount of 6urfac~nt ~nd a 6uds depres~or. Bleach
is not disclosed. U.S. Patent No. 4,147,653 is omehwat
similar, optionslly including Cl-(hypochlorite) bleach
but no organic ~urfactant or foam depressant. The product
i6 described, moreover, as 8 detergent slurry with no apparent
thixotropic properties.
U.S. Pstent No. 3,98S,668 de6cribes ~br~sive ~couring
cleaners of gel-like consistency containing ~1) 0u~pending
agent, preferably the Smectite ~nd ~ttspulgite types of
clay; (2) abrasive, e.g. silics ~and or perlite; and (3)
filler comprising light den~ity powdered polymer~, expanded
perlite and ~he like, which has ~ bouysncy and thus stabilizing
effect on the composi~ion in ~ddition to serving aE a bulking
agent, thereby replacing w~ter o~herwise ~vailable for
unde~ired supernatant lsyer formation due to leaking ~nd
phase dest~bilization. The foregoing are the essential
ingredien~s. Optional ingredients include hypochlorite
bleach, bleach ~table surfactant and buffer, e.g. silica~es,
carbonates, and monophosphates. Builders, such ~s NaTPP,
c~n be included ~s ~urther optional ingredient~ to supply
or supplem building function not provided by the buffer,
3 1
the amount of such builder not exceedin~ 5% of the total
composition, according ~o the patent. Maint~nsnce of the
desired (greater than) pH 10 levels is achie~ed by the
buffer/builder component High pH ic ~aid ~o minimize
decompofiition o~ chlorine bleach ~nd undesired inter~ction
between surf~ct~nt ~nd bleach. When present~ NaTPP is
limi~ed to 5%, as ~t~ted. Fo~m killer is not diqclosed.
In U.K. P~tent Application GB 2,116,199A and GB
2,140/450A, both of which sre ~ssigned to Colgate Palmolive,
liquid ADD composition6 are di6clo~ed which hsve properties
desirably char~cterizing thixotropic, gel-type 6tructure
and which iDclude each of the various ingredient~ necessary
for effective detergency wit.h an automatic dishwa~her. The
normally gel-like ~queous ~utomstic ~i~hwasher detergent
composition having thixotropic properties includes ~he
following ingredients, on a weight basi~:
(a) 5 to 35% slkali met~l tripolypho~phate;
(b) 2.5 to 20% 60dium silicate;
(e) o ~0 9V/o slkali metal c~rbonate;
(d) 0.1 ~o S% ehlorine blesch ~able, w3ter dispersible
organic de~er~ent active material;
(e) 0 to 5~L chlorine bleach 6tAble foam depre~ant;
~P (f) chlorine bleach compound in an amount to provide
: abou~ 0.~ to 4V/~ of sv~ilable chlorine;
(g) ~hixotropic thickener in sn ~moun~ sufficient
to provide the composition with thixotropy index of ~bout
, 2.5 to 10; and
: (h) sodium hydroxide, as necesssry, to adjuæt pH.
ADD compositions so formulated are low-foaming;
sre re~dily soluble in the washing medium snd mo~t effective
at pH value~ best conducive to improved oleaning performance,
Il ~ 3 ~
viz, pH 10.5-13.5. The composi~ions are normally of ~el
consi6tency, i.e. a highly viscous, opaque jelly-like material
ha-~ing Bingham plas~ic character ~nd thu~ rela~ively high
yield value6. Accordingly, a defini~e 6hear force is necessary
to initia~e or increase flow, ~uch ~6 would obtain within
the a~itated diæpenser cup of ~n energized ~u~omatic di~hwssher.
Under such conditions, the composition i6 quickly fluidized
and e8~ily di~per~ed. When the ~hear force is discontinued,
the fluid compo ition quickly revert~ ~co ~ high viæcosity,
Bingham plastic state clo~ely ~pproxim~ting i~ prior consistency
UOS. Patent 4,511,487 dated April 16, 1985 describes
a low~foaming deter~ent paæte for dishwashers. The patented
~hixotropic cleaning sgent has a vi~cosity of at least
30 Pa. 6 a~ 20C as determined with a rot~tional vi~cometer
at a spindle speed of 5 revolutions per minute. The composition
i~ bssed on a mixture of finely divided hydr~ted 60dium
mets6ilicate, ~n ~ctive chlorine compound snd ~ ~hic~ening
sgent which iB a foliated silicate of the hectorite type.
Small amount of nonionic ~ensides 8nd slksli metal carbonates
and/or hydroxides msy be used.
The form~tion of organoclayc by the inter~ction
of clays (~uch as ben~onite and hec~orite) with organic
compounds 6uch ~ quaternary ~mmonium salts, has also been
de~csibed (W.S. Mardis, JAO~S, Vol. 61, No. 2, p. 382 (1984)).
While the~e preYiously di6closed liquid ADD formulations
are not æubject or are subjec~ to a lesser degree to one
or more of the above described deficiencies, it has been
found that in sctual practice, still further improvements
in physical stability ~r~ required to increa~e the shelf-life
of ~he produc~ and thereby enhance consumer acceptance.
~ 3 1 ~
62301-1~08
In the above-mentioned Canadlan application Serial
No. 511,518 the physieal stabili~y of clay based thi~otropic
liquid formulations is improved by addition thereto of small
amounts, ~or example, from about 0.0~ to 1~ by weight, of a
polyvalent metal. salt o~ a long chain fatty acid, such as
aluminum stearate.
While the combination of clay thickener and fatky
acid salt stabilizer has been found to prov:Lde satisfac~ory
long term stablli~yr such as absence of phase separation for
periods up to 12 weeks and longer, the addition of clay to
these formulations has several drawbacks.
For example, when using clay thickeners the order of
addition of the various ingredients and the control of the
process conditions during ~ormulation of the compositions ~s
critical to obtain the desired thixotropic properties and low
foam characteristics. In addi.tion, the clay thicke~ers are
expensive materials and can contribute significantly to the
final produet cost to the consumer. In some cases the clay
thickeners may actually interfere with overall cleaning
performance.
Accordingly, the invention seeks to provide stable
thixotropic aqueous suspensions which avoid the use of clay
. thiekeners.
The invention also seeks to provide liquid ADD
- compositions having thixotropic properties with improved
~: physieal stability and rheological properties.
The invention further seeks to provide thixotropic
liquid ADD compositions having reduced levels of thixotropic
thickener without adversely effecting the gerlerally high
viscosities at low shear rates and lower viscosities at high
shear rates wh:Lch are charaeteristic of the desired th:ixotropic
~ 3 ~
62301-1~08
properties.
More broadly, this invention aimC~ to provide stable
aqueous thixotrop:Lc non-clay based composii;ions especially
liquid automatic dishwasher detergent pastes or gels, by
incorporatiny ln the clay-free aqueous suspension a minor
amount of a fatty acid effective to inhibit the settling of the
suspended particles and to prevent phase separation.
The invention, which will become more readily
understood from the following detailed de~crip~ion and
preferred embodiments thereof, relates to the incorporation
into an aqueous liquid detergent composition or a small but
effective amount of a non-clay, non-polymeric thixotroplc ayent
which is a long chain fatty acid.
The invention provides an aqueous gel-like
thixotropic clay-free and polymer thickener-free liquid
cleaning composition which comprixes from about 25 to 75% by
weight of water, from about S to 35% by weight of an alkali
metal builder salt, at least one organic detergent, and a mono-
ZO or polycarboxylic acid havlng from 8 to 22 carbon atoms, orthe dimers or trimers thereof in an amount of from about 0.03
to about 0.5% by weight of the total composition to lmpart to
said composition stability against phase separation and
~hixotropic properties,
E 7
~L3~ $~
6~301-1408
In accordance with this particular aspect, the
invention particularly provides a normally gel-like aqueous
automatic dishwasher detergent composition haviny thixotropic
properties which include, on a ~eight basis:
(a) 5 to 35% alkali metal tripolyphosphate;
(b) 2 5 to 4Q% sodium silicate;
Ic) 0 to 9% alkali metal carbonate;
(d) 0.1 to 5% chlorine bleach stable, water-dispersible
organic detergent active material;
(e) 0 ~o 5% chlorine hleach s~able foam depressant;
(f) chlorine bleach compound in an amount to provide
about 0.2 to 4% of available chlorine;
(g) 0.03 to 0.5% of a lony chain fatty acid;
(h) 0 to 8~ sodium hydroxide; and
(i) balance water, preferably free of thickeners which
are clay thixotropic thickeners.
Also related to this speclfic aspect, the invention
provides a method for cleaning dishware in an automatic
dishwashing machine with an agueous wash bath containing an
effective amount of the liquid automatic dishwasher detergent
~LADD) composition as described above. According to this
aspect of the invention, the LA~D composition can be readily
poured into the dispensiny cup of the automatic dishwashing
ma~hine and will, within just a few seconds, promptly thicken
to its normal gel~like or pasty state to remain securely within
the dispensiny cup until shear forces are again applied
thereto, such as by the water spray from the dishwashln~
machine.
~ 3 ~
62301-1408
The invention will now be clescribed in great,er detail
by way of specific embodiments thereof and with the aid of the
following drawing in which ~he
FIGURE is a graphic representation of thixotropic
index of two diferent formulations according to the present
invention and a clay thickened liquid automatic dishwasher
detergent composition as disclosed in GB 2,140,450A.
The LADD products of the prior disclosures in the
aforeme~tioned G.B. 2,116,199A, GB 2,140,450A and Canadian
Serial No. S11,518 exhibit improved rheological properties as
evaluated by testing
~; :
i
,
; ,~
;''~
` :`
D 8a
~ 3 ~
product viscosity 85 a function of shear rate. The compositions
exhibited higher viscosity st a low shear rate and lower
vi~cosity at a high shear rste, the data indica~ing efficient
fluidization snd gellation well within the shear rate~
extant within the 6tandard dishwasher machine. In prscti~al
terms, this means improved pouring ~nd processing characteristics
as well ~s le~s leaking in the machine clispenser-cup, eompared
to prior liquid or ~el ADD prod~cts. For ~pplied shear
r~es eorrezponding to 3 to 30 rpm, viscoæitie6 (Brookfield)
corre6pondin~1y ranged from about 70,000 to 30,0Q0 cps
to ~bout 3000-7000 cps, a8 mea6ured at r~om temperature
by meanB of &n LVT Brookfield viscometer after 3 minutes
u~îng a No. 4 6pindle. A shear rate of 7.4 eec 1 corresponds
to ~ spindle rpm of abou~ 3. An spproximste ten-fold increase
in shear rate produces ~bout ~ 3- to 9-fold reduction in
viscosity. The compositions of the ~ssignee's prior invention
thus exhibit threshold fluidizstions ~ lower ehear rste~
~nd of significantly greater ex~en~ in terms of incremental
increase~ in shear rate versu~ incrementsl decrease in
vi~cosity. This property of the LADD product~ of the prior
invention i~ 6ummarized in terms of ~ thixotropic index
(TI) which is the ~atio of the apparent vi~cosity at 3
rpm ~nd ~ 30 rpm. The prior compositions have ~ TI of
from 2 to 10. The LADD compositions ~hould exhibit 6ubst~ntial
and quick return to prior quiescent Btate consistency when
the shear force is discontinued.
While the determination of ~hixo~ropic index TI
as a ratio of apparent viscosity at 3 snd 30 rpm provides
a satisfac~ory measure of product usefulness further research
and experience has shown that a more reliable mea~ure of
thixotropic index and product usefulness as a liquid ADD
g_
3 3~ ~8~
is provided by determining thixotropy as a measure of the
area in the hysterisis loop resulting frsm plotting, under
the conditions described below, æhear stress, S, as a function
of ~hesr rate, n, when the shear rate i6 increased from
0 to a maximum value and ~hen returned ~o 0. The larger
the ~rea in the hy~teri~is loop, the ~reater is the thixotropic
index. In ~erms of appsrent viscosity, it has 8160 been
as~ertained that ~o long BS the vi~c06ity st room tempera~ure
(22~1C) measured in a Brookfield Vi~co~imeter HATD, using
a number 4 spindle ~t ~0 rpm, is less than about 20,000 cp~,
the composition ean be readily ~haken B0 ths~ ~ ~hixotropic
composition can be easily "fluidized" or "liquefied" to
allow the product to be di~pen6ed through ~ co~ventional
squeeze tube bottle or other convenient di6penser.
The present invention i6 b~sed upon the surprising
discovery ~hat the ~ame or improved rheological propertie~
a~d physicsl stability, i.e. resi~ance to phae ~eparation,
~et~ling, etc., as in these prior liquid aqueous ADD compositions
can be achieYed t ~t significantly lower cost and without
any particular processing re~uirements, by ~dding to the
composition ~ ~m~ll but effective amount of a long chsin
f~tty acid in pl~ce of ~he clay thixotropic ~hickener and,
where used, al o the metal 6~1t of ~he fatty ~cid. At
the same time, impr4vemen~s in ~potting snd filming performance
~i.e. fewer spots and reduced filming) can be achieved~
As an example of~the improvement in rheological
properties over a standard clay bs~ed thixotropic liquid
ADD, reference is made to the attsched drawing which is
a plot of 6hear stress, S, as a function of shear rate,
n, for aclay based LADD (3 wtV/o clay) (curve 1) ~nd
for two similar LADD compositions in which the clay is
rcplaced by 0.06 wt% ste8ric acid (curve 2) or by 0.08 wt%
~ 3 ~
~tearic acid (curve 3). Shear stress, S, is measured in
a sta~ic experiment using a Haake RV-3 machine provided
with a coaxial cup. The sample is p~aced in ~he ou~er
cup and the inner cup is rotated by the m~chine at progre6sively
higher shear r8te6 to ~ maximum o 113 ~ec~~ and then the
~hear ra~e iB progressively lowered to zero. The response
is sutomatically recorded ~s the ~hear stre~. The experiments
were csrried ou~ u~ing ~n MN II ~ensor system (con6tant
values, A-3.76 Pa, M~0.9 ~eC~l). The a~ea bet~een the
resulting curved lines for each ~ample is ~ measure of
thixotropy, with lar~er areas indic~ting higher thixotropy.
The yield point of e~ch sample can also be determîned from
the curve~ ahown in the figure; the yield point i~ the
maximum etre~s in ~he curve of shear stre~s ver6us Ghear
rate. At the 6ame ~ime, ~he phy~ical tability i6 ~uch
that even a~ter 6iX weeks or longer, over temperature ranges
extending from nesr free~lng to 40~C snd ~ore, the compositions
containing the ~tty acid thickener6 do not undergo ~ny
vi~ible phase BeparatiOn.
The preferred long chain fstty ac;ds sre the higher
aliphatic fatty monocarboxylic scids having from 8bout
to about 22 carbon atoms, more prefer~bly from sbout
10 to 20 carbon ~toms, ~nd especislly preferably fr~m about
12 to 18 carbon atoms, inclusive of the carbon atom of
the carboxyl group of the fstty ~cid. Polycsrboxylic acids
can slso be used. The aliphatic radical msy be ssturated
or unsaturated and may be ~rsight or branched. Straight
chain saturated fatty acids are preferred. Mixtures of
fatty acids may be used, such a6 those derived from natural
sources, such as tallow fa~ty scid, coco fat~y acid, soya
fatty acid , etc ., or from synthetic ~ources available ~rom
`` ~3~ ~3~
~ indu tri~l manufac~urin~ processes.
¦ Thus, ex~mples of the fat~y ~cids which can be .
¦ used as thi~kener~ in place of clay or polymeric ~hickeners
¦ include, for example, decsnoic acid, l~uric ~cid, dodecanoic
¦ ~cid, palmi~ic ~cid, myristic acid, ~tearic acid, oleic
acid, eicosanoic acid, tallow fstty acid, coco fat~y scid,
l fioys fatty ~cid and mixtures of ~hese acid~. In sddition,
; ¦ the dimers or trimers of these scids can ~180 be used.
¦ Stearic acid snd mixed ~a~ty ~cid6, e~g. cocofa~ty scid,
; ¦ are preferred.
¦ Within the ranges of carbon chain lengths of the
¦ monocarboxylic fatty ~cid~ ~pecified herein the viscosity
¦ of the product tends to decrease as the number of carbon
¦ atoms in the monocsrboxylic f~tty acid decrease6. No systematic
¦ trends are observed for the dimer6 or trimers or polybssic
: ¦ c~rboxylic scid8.
~ ¦ The ~mount of the fatty ~cid thicker.er to achieve
: ¦ the desired values of thixotropy and physicsl stability
¦ will depend on such f~ctorc ~s the nature of the fatty
¦ ~cid, detergent ~c~ive compound, inorganic ~alts, especially
¦ TPP, other LADD ingredient~, a~ well a~ the ~nticipated
storsge ~nd shipping conditions.
: ~b ~ Generally, however, amou~ts of ~he f~tty acid thi~otropic
agent in the range of from ~bout 0.03 to 0.5%, prefer~bly
from about 0.03 to 0.2%, especially preferably from about
0.03 to 0.08%, provide the long term ~tability ~nd absence
:: of phase ~eparation upon ~tanding or during tr~nsport at
. both low and eleYated temperature6 ss are required for
: 8 co~mercially acceptsble product.
j -12-
3 ~
Generally, LADD effectiveness is d;rectly rela~ed
to (a) available chlorine levels; (b~ alkalinity; ~c~ ~olubility
in wa~hing medium; snd (d) foam inhibition. It i6 preferred
herein that the pH of ~he LADD compo&ition be st lea6t
~bout 9.5, more preferably from about 10.5 to 13.5 ~nd
most preferably st least ~bout 11. 5 . At the relatively
lower pH valueæ, the LA~D product i6 too vi~cou6, i.e. solid-lik .
and thus not readily fluidized under the ehe~r-force level6
cre~ted within the dispen~er cup under normal m~chine operating
conditions, In es~ence, the egmpo6ition 106e6 much, if
not all, of it~ ~hixotropic character. Addition of NaOH
is thus often needed ~o increase the pH to within the above
range~, snd to incresse flowsbility properties. The presence
of carbonate is also often needed herein, since it act6
a8 ~ buffer helping to maintain ehe de6ired pH level.
Exces~ c~rbonate i~ to be avoided, however, 6ince it m~y
esuse the formation of needle-like cry6tal~ of srbon~te,
thereby impairing the st~bility, ~hixo~cropy and/or de~ergency
of the LADD produc~, ~16 well ~s impairing the di~pen~ability
of the product from, for exampl~, squeeze tube bo~les.
Cau~tic ~oda (NaOH) 6erves the further function of neu~ralizing
the phosphoric or phosphonic acid ester foam depresssnt
when pre~ent . About 0 . 5 ~o 3 wtVZ of NaOH and ~bout 2 to
9 wtC/o of sodillm carbonste in the LADD compo6ition are typical,
lthough it ~hould be noted that sufficient alk21inity
m~y be provided by the NsTPP and ~odium silicate.
The NaTPP may employed in the LADD composition
in 8 ran8e of about 8 to 35 wt%, prefer~bly about 20 'co
30 wt%, and should preferably be free of heavy metal which
tend~ to decompose or inactivate the preferred 60dium hypochlorit
and other chlorine bleach compounds. The NaTPP ~ay be
"` ~L 3 ~
anhydrous or hydrated, includin~ the ~table hexahydr~te
with a degree of hydration of 6 corresponding to about
18% by weight of w~ter or more. Actually, in view of the
stability of the hexahydrate, the presence of some w~er
of hydration is highly effective, ~erving le i~ thought
to form seeds of the stsble hexahydrate which expedite6
hydration ~nd solubiliz~tion of the remaining N~TPP particles.
If only the hexshydrate i5 used, the de~ergent product
may be too liquid ~nd may have llttle if ~ny thixotropic
character. Conversely, if only the ~nhydrou~ NaTPP i6
used, the product may, in some c~ses, be too thick and,
therefore, un~uitable. Especially preferred LADD compositions
are obtained, for example, when using a 0.5:1 to 2:1 weight
ratio of snhydrous to hexahydrated N~TPP, vslues of about
1:1 being p~rticularly preferred.
Foam inhibition is important:to increase di~hwasher
mach~ne efficiency sod minimize destabilizing effects which
might occur due to the presence of exce~s fo~m within the
washer durin~ u~e. Foam m~y be 6ufficiently reduced by
suitable selection of the type and/or smount of detergent
sctive material~ the main foam-producing component. The
degree of foam i8 also ~omehwat dependent on the hardne6s
of the wash~ater in the mschine whereby sui~able sdjustment
of the proportions of NaTPP which has a wster softening
effect may aid in providing the desired degree of foam
inhibition. However, it is generslly preferred to include
a chlorine bleach stable foam depressant or inhibitor.
Particularly effective are the alkyl phosphonic acid es~ers
of the formula
-lb-
HO ~ P ~ R
OR
l ~ . available for example from BASF-Wyando~e (PCUK-PAE), snd
: especially the slkyl acid phosphate est:ers of the formula
O
HO - P - 0
OR ~
sv~ ble, for example, from Hooker ~SAP) and Knspsack
(LPKn-158), in which one or both R groups in ~ch type
of ester may represent independenely a C12~0 alkyl group.
Mixtures of the two types, or any other chlorine ble~ch
~table types, or mixtures of mono- and di-es~ers of the
same type, may be employed. Especially preferred iæ ~
mixture of mono- and di-C16_lg alkyl ~cid phosphate esters
6uch ~s monostearyl/distearyl acid phosphates 1.2/l (Knapssck).
When employed, proportions of 0.01 to 5 w~L, prefersbly
0.1 to 5 wt%, especially ~out 0.1 to 0.5 w~/O~ of foam
depre~snt in the compogition i6 typ$c~1, tbe weight r~tio
of detergent active component (d) to fosm depre~sant ~e)
gener~lly ran~ing from about 10:1 to 1:1 ~nd preferably
~bout 4:1 to 1:1. Other defoamers which may be used include,
for example, the known ~ilicones.
Although any chlorine bleach compound may be employed
in the composi~ions of this invention, such ~ dichloro-
isocyanurate, dichloro-dimethyl hydantoin, or chlorinated
TSP, al~sli metal, e.8. potas6ium, li~hium, magnesium and
especially ~odium, hypochlorite is preferred. The composition
should contain sufficient chlorine bleach c~mpound to provide
about 0.2 to 4.0% by weight of available chlorine, ~s determined,
for ex~mple, by acidificstion of 100 parts of the composition
with exce~ hydrochloric acid. A ~olution containing abou~
~ ~ 1rG~ G ~k
Il ~ 3 ~
0.2 to 4.0% by weight of ~odium hypochlorite contains or
provides roughly the same percenta~e of svsil~ble chlorine.
About 0.8 to 1.6% by weight of aY~ilable ehlorine is especially
preferred. For ex~mple, ~odium hypochlorite (N~OCl) ~olution
of from ~bout 11 to about 13% ~vailsble chlorine in ~moun~
of about 3 to 20%, preEerably ~bou~ 7 to 12%, c~n be ~dv~nt~geous Y
u~ed.
The ~odium ~ilic~te, which provides ~lk~linity
~nd proteetion of h~rd ~urf~ce6, such as fine china glAze
and pattern, is employed in Bn ~mount r~ngin~ from s~out
2.5 to 40 wt%, prefersbly ~bou~ 10 to 35 wt%, in ~he composition.
At the higher levels 6pecified herein for example at level6
grester than about 10 w~% the ~ilicste ~160 provides incres~ed
antiRpottingaction. The ~odium BiliC9te i6 generally added
in the form of ~n squeous ~olution, prefer~bly having sn
Ns20:SiO2 r~tio of about 1:2.2 to 1:2.8, for example, 1:2.4.
Mo~ of the o her co~ponen~s of ~he co~po6ition, e~pecislly
NaOH, sodium hypochlorite and fosm depres~ant ~ay ~l~o
be sdded in the form of an ~queous disper~ion or solution.
I)e~cergent ~ctive materiAl u~eful herein mu~ be
stable in the presence of chlorine blesch, especi~lly hypo-
chlorite bleach, ~nd ~hose of the org~nic snionic, amine
oxide, phosphine oxide, sulphoxide or betsine w~er d~per~ible
surf~ctsnt type~ are preferred, the first mentioned anionics
being most preferred. They are u~ed in amount~ ranging
from about 0.1 ~o 5~/~ preferably about 0.3 ~o 2.0~/~. Particularly
preferred &urfactant~ herein are the linear or branched
alkali metal mono- and/or di-~Cg_l4~ ~lkyl diphenyl oxide
mono snd/or disulpha~es, commercially available for example
as DOWFAX (Registered Trademark) 3B-2 ~nd DOWFAX 2A-l.
~ 3 ~
In ~enersl, the par~ffin sulphonates tend to impair, if
not destroyt thixotropy~ having been found to unduly inerease
viscosity causing Revere shearing force problems. In addition,
the surfActan~ ~hould be compatible with the other in~redients
of the compo~ition. Other suitable ~urfsctant~ in lude
the primary alkylsulphate~, alkyl~ulphonates, ~lkylaryl-
sulphonate~ ~nd ~ec.-~lkyl~uphate~. Examples include sodium
Clo-Clg alkylsulphate~ such a~ ~odium dodecyl6ulphate ~nd
~odium tallow alcoholsulphate; ~odium Clo-Clg alkanesulphonates
6uch flS sodium hexsdecyl-l-sulphonste ~nd eodium C12-Clg
alkylbenzenesulphonates such as sodium dodecylbenzene~ulphonates.
The corresponding pot~asium 6alts msy also be employed.
As other ~uitable Rurfactants or detergents, the
amine oxide ~urf~ctaot~ are ~ypically of the structure
R2RlNO, in which each R repre6ent~ a lower alkyl group,
for in~tsnce, methyl, ~d Rl represent~ a long ch~in alkyl
group ~avin~ from 8 to 22 carbon ~tom~, for instance a
l~uryl, myri6tyl, palmityl or cetyl group. In~tead of
an ~mine oxide, ~ corre6po~ding ~urfsct~nt pho~phine oxide
R2RlPO or ~ulphoxide RRlSO can be employed. Bet~ine ~urf~ctants
are typically of the ~truct~re R~RlN - R"COO-, io which
e~ch R repre~e~t~ ~ lower ~lkylene group having from 1
to 5 carbo~ ~oms. Specif~c examples of these ~urfact~nt~
sre lauryl-dimethylamine oxide, myristyldimethylamine oxide,
the corresponding pho6phine oxides and sulphoxide~, ~nd
the corresponding betsines, including dodecyldime~hylammonium
acetate, tetradecyldiethylsmmonium pent~noate, hexadecyl-
dimethylammonium hexanoa~e and the like. For blo,degradability,
the alkyl groups in these surfactant~ ~hould be linear,
and auch compounds sre preferred.
I ~ 3~ ~8~
Surfaetants of the fore~oing ~ype, all well known
in ~he art, ~re described, for example, in U.S. Patent6
3,985,668 and 4,271,030.
The ~mount of water contained in ~hese composition6
~hould, of course, he neither so high a6 to produce unduly
low vi6c06ity and fluidity, nor ~o low ~s ~o produce unduly
high vi~cogity and low flowsbili~y, thi.xotropic propertie~
;n either ca~e being diminished or de6troyed. Such ~mount
i6 readily dete~mined by routine experimentation in ~ny
particul~r in6tance, generally ranging from about 25 to
75 wt%, preferably about 55 to 65 wt%. The ~ater should
sl~o be preferably deionized or ~oftened.
Other conventional ~ngredient~ may be included
in these compo~ition6 in 6mall ~mounts, generally le~
~han about 3 wt%, ~uch u~ perfume, hydrotrspic agent~ ~uch
as the sodium ben~ene, tolue~e, xylene and eumeRe sulphonates,
preserv~tives, dyestuff~ and pigments snd the like, ~11
of cour~e being 6table to chlorine ble~ch compound and
high alkalinity (propertie~ of ~11 the c4mponents). E~p~cially
p~eferred for coloring ~re the chlorinsted phthalocysnines
and polysulphides of aluminosilicste which proYide, respectively,
plessing green ~nd blue tints. TiO2 may be employed for
whitening or neutralizing off-shade6.
The liquid ADD eompo~itions of thi~ invention are
resdily employed in known msnner for washing dishe~, other
kitchen utensils ~nd the like in an automatic dishwasher,
provided with a suitable de~ergent dispenser, in an aqueou6
wa6h bs~h containing sn effec~ive amount of the composition.
While the invention has been particularly described
in connection with its application to liquid automatic
di~hwasher detergents it will be readlly understood by
~ 3 ~
one of ordinary skill in the art that the benefits of thixotropy
and phy~ical ~tability which are ob~ained by the addition
of the fatty scid may 2pply equally well ~o repl~cement
of clay or polymeric thickener6 in other clay or polymeric
b~ed thixotropic su6pension~, 6uch a6 the scouring paste
formulations de~cribed in the aforemen~ioned U.S. Patent
3,985,668, dent~l pa~es, and the like.
The invention may be put into pr~ctice in variou6
ways and ~ number of ~pecific 2mbodiments will be described
to illustrate ~he invention with reference to the ~ccompanying
example6
All amounts and proportions referred to herein
are by weight of the compo6ition unls~s otherwise indicated.
In order to demonstrate the effect of the f~tty
~cid thickener liquid ADD formulation~ ~re prepared with
varying amount6 of f~tty acid thixotropic thickener
(Run6 1, 2 ~nd 33 as ~hown in Table 1. For comp~ri60n,
~ simil~r compo6ition (Run No. 4) corre~ponding to the
composition of Exsmple 1 of GB 2,140,45UA i~ prepared sccording
to ~he procedure disclosed in æaid example.
~"
¦ TABLE 1
¦ ~ _ Run No.l Run No.2 Run No.3 Run No 4
¦ Water 32.99 32.96 32.94 41.92
¦ Stearic Acid 0.03 0.06 0.08
Clay (Gel Whi~e GP) - - 3.00
Sodium Silica~e
I (47.~% ~olution of
¦ Na20:SiO2 ratio of
1:2.4) ~5.00 25.00 ~5.~0 13.73
¦ Sodium tripoly-
I phosphate (sub-
¦ 6tantially an-
I hydrous9i.e. flbout
¦ 3% moi~ture~ 12.00 12.00 12.00 12.00
Sodium tripoly-
I phosphate hexa-
¦ hydrate 12.00 12.00 12.00 12.00
Sodium Carbonate
l (Soda A~h) 7.00 7.00 7.00 7.00
¦ Sodium Hypochlorite
(13% available
¦ chlorine) 7.61 7.61 7.61 7.61
I Surfactant (Dowfsx
¦ 3B-2, 45% Na
¦ mono- and di-decyl
I diphenyloxide
I di~ulfon~te-
¦ ~queous solu~ion)0.80 0.80 0.80 0.80
¦ Antifoamin~ ~gent
¦ ~Knaps~ck LPKn 158,
I mixture of mono- and
I di-~tearYl (~16-C18)
1 slkyl ester~ of phoR-
phoric ~cid, mole
¦ ra~io about 1:1.30.16 0.16 0.16 0.16
I C3ustic Soda 501ution
1 ~50% NaOH) 2.40 2.40 2.40 2.40
Color (Gr~phitol
Green) 0.01 0.01 0.01 0.01
100.00 100.00100.00 1~0.00
A ~smple of each of~he formulations of Run Nos.
2 and 3 and ~he comparative cl~y bs~ed formul~tion (Run
No. 4~ is subjected to the shesr ~tress measurement using
the Haake RV-3 machine as described above to dete~mine
thixotropic index and yield poine. The resultæ are shown
in the ~ttached figure where curve 1 i~ ba~ed on the s~mple
of Run No. curve 2 is based on the ssmple of Run No. 2,
-20- .
~3~8~
and curve 3 i6 based on the sample of Run No. 3. The v~lue
of yield p~in~ - the maximum value of ~hesr stress, S,
i~ ~hown in Table 2.
Other propertie6 are al60 BhOWn in Table 2, including
~he apparen~ visco~ity, n. measured on ~ 24 hour old Bample
using a Brookfield HATD vi~c06imeter, using ~ No. 4 ~pindle
~t 20 rpm (T=22~1C); den~ity, capill~lry dr~ln~ge rate,
stability and centrif~ga~ion. C~pillary dr~in~ge rate
~CDR~ is a mes6ure of ætability with hi~her v~lue~ indicative
of higher ~tability. CDR ~ea~urement~ ~re ~sde by the
following procedure: No. 1 Whatman filter paper havin~
a 6.4 cm diameter circle trsced thereon i8 laid on ~ fl~t
~la~8 plate, lO cm x lO cm. A plas~c tube, 6.4 cm long,
3.4 cm diameter, i~ placed in a staDding position, centered
on the circle. The tube is filled with ~he ~ample liquid
ADD composition (sfter standing for one dsy). The ti~e
needed for ~he 601vent to ~eep out of the tube ~nd re~ch
the traced e~rcle i6 me~sured. Time iæ ~e~sured on ~hree
~ides of the circle and averaged. Faster time0 mesn that
th~ gel iB not ~ucce~fully ~etaining ~he solvent (water~
which can ~hen leak into the filter paper. Time6 greater
than about 7 minutes (all sampl2~) are ~ccept~le. The
stability mea~urement i5 made by placing the ~ample in
a glass bottle, left ~t room temperature, and observin~
the % ~eparation a~ the end of 4 weeks. The centrifugation
test is al~o a mea6ure of s~ability. Glass cen~rifuge
tubes are ~illed with equal volumes of each 6~mple and
are 6pun vertically, i.e. ~n a pl~ne parsllel to ~he ground,
in a Sorwall centrifuge, for 25 minutes at 500 rpm. The
volume of clear liquid ls then measured. The lesults are
:~ 3 ~
reported as the ratio of the height of clear liquid to
to~al height of ~ample multiplied by 100, i.e.
total height llquid x 100, L~wer numbers indicate g
6tability.
TABLE 2
Property___ Run No.l ~ ~ Run No.4
~i~co~ity, cp6 ~1,4~ 10,660 11,260 5,100
dynes/cm2 - 372 720 392
Density, g/ml 1.35 1.36 1.34 1.37
CDR (minute~) - 8.5 10.0 7.0
St3bili~y (4 w~ekæ
~eparation <1.0 0.0 0.0 5.0
Centrifug~tion Cl... ~ 0.0 :0.0 5.0
The data in Table 2 clearly 6how~ the su~perlor
pha6e ~eparation stability of ~he ~earic ~cid b~6ed formulations
88 compared to the clay ba~ed formuls~ion. The~e rexult~
coupled wi~h the thixotropy charscteristics indiested by
the graphicsl representations in the figure fur~her demon~trate
the superiority of the ~nvention formul~tion~ with re~pect
to di~hwasher cup leakage.
~' ~
Each of the formulations of Runs 1-4 of Example 1
~re tested to compare eleaning performance ~buildup of
B SpOtS and films on glassware) using a Kenmore~dishwasher
u~ing tap water temperature at 130~F and 120 ppm hardness.
-2~-
The test procedure is described in AS'FM D3566-79, except
th~t only four cleaning cycles are used. The filming and
spotting are evalu~ted sccording to the following ~cale6:
r11- r~ 5~AI.
1. Best, no ~pparent film
2. Filming ~light, bec~ming appsrent
3. Notice~ble film, increasing
4. Continued incre2ee of significhnt fllm
5. Filming becoming exce~ive
6. Filming high, exces6ive buildup
7. Continued increase of exces6ive film.
Spot Ratin~ Scale
A. Best - no 8pot8
B. Very few ~pots ~pparent
C~ Di6tinct
D. Signific~nt coverage ~pproximately ~070.
The re6ult6 are 6hown in Table 3:
TABLE 3
Run No. Pe~ Ratio~
~ Film
1 B 1,2
2 B,C 1,2
3 B,C 2,3
4 C ~,3
:~
-23-
~3~$~
Similar resul~ to tho~e de~cribed sbove are obtained
if the 6~earic ~cid i8 repl~ced by is0l3te~ric ~cid, myristic
~cid, p~lmitic ~cld, l~urir ~cid, Emphol~imer ~cid, Emphol
~rimer acid t)r Emphol 1052 polyb~sic ~cid.
In addition ~o the 6uperior phy~ical ~tsbility,
thixotropy and cle~ning performance, the composi~ion~
of thi~ invention ~sve the addition~l ~ignificant sdvanta~e
of not requiring ~ny p~rticular order of addition of the
re~pective ingredient~. All of the ingredient6 can be
added in ~ny order or ~imultaneously to ~ ~ingle pot,
mixer, etc., ~nd stirr~d until a uniform homogeneou6 mixture
i~ ob~sined. ~lixing c~n be done ~t room temper~ture or
st elevated tempersture. It i~ rlot neCes~ary to premit
~ny of the ingredients or ~co u6e different ~hear mi~ing
condition~ .
~ r,~
~ ~-
-24-
